These are the most popular Journals in our community (as surveyed at ICOB 2008) and their latest table of contents for you to browse.
Wiley InterScience : Journal of Biophotonics
Show articles…Light delivery and monitoring during photodynamic therapy (PDT) is often limited by the need for a physical link between the light source, detectors and the treatment volume. This paper reports on the first in vivo experiments performed with a fully implantable telemetric system, designed for a rat glioblastoma model. In this system, light delivery is performed using a solid state optode containing 2 LEDs, and 4 photodiodes which will be used to monitor light delivery in future experiments. Powering and communication is achieved by means of an inductive link. The implant may remain in the animal for extended time periods, making it particularly interesting for performing metronomic PDT. In this paper, we demonstrate the feasibility of in vivo light delivery and biocompatibility of the device.. Activation of the inductive link as well as illumination of the brain by the LED did not influence animal behavior during or after treatment. We show that the implant can remain in the animal for two weeks without causing serious biological reactions. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear optical imaging of human skin and of polychromatic microspheres was carried out to compare and evaluate the imaging properties of three different excitation femtosecond lasers: a spectrally tunable 80 MHz Ti: sapphire oscillator that produced 100 fs pulses (spectral width [sim]10 nm) and two ultrabroadband Ti: sapphire oscillators with repetition rates of 85 MHz and 1 GHz. The latter of these two and the 100 fs laser were combined with a laser scanning microscope (TauMap). The intensities of images of the polychromatic microsphere samples obtained with both lasers are in accordance with the usual dependence of two-photon processes on laser pulse parameters, i.e. the intensity is proportional to the square of the mean laser power and the reciprocal pulse duration. In contrast to that, skin images measured with all three different excitation sources with mean powers of each laser adjusted to the particular pulse length and repetition rate exhibited discrepancies from this relation. For characterization of the ultrabroadband GHz laser, the measurements are supplemented by spectra of second-harmonic-generation signals of urea and collagen. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Photodynamic inactivation of bacteria (PDIB) is considered a new approach for the struggle against multiresistant bacteria. To achieve a sufficient level of bacteria killing, the photosensitizer must attach to and/or penetrate the bacteria and generate a sufficiently high amount of singlet oxygen. To optimize PDIB, the direct detection and quantification of singlet oxygen in bacteria is a helpful tool. Singlet-oxygen luminescence is a very weak signal, in particular in living bacteria. We first performed experiments in aqueous photosensitizer solution to optimize the luminescence system. We eliminated non-singlet-oxygen photons, which is important for the quantification of singlet oxygen and its rise and decay rates. This procedure is even more important when the laser excitation beam is scattered by bacteria (diameter 1 [mu]m). In suspensions with both Gram-positive and Gram-negative bacteria we then clearly detected singlet oxygen by its luminescence and determined the respective rise and decay times. The decay times should provide an indication of localization of singlet oxygen and hence of the photosensitizer even in small bacteria. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Singlet oxygen (1O2) is the major cytotoxic agent responsible for cell killing for type-II photodynamic therapy (PDT). An empirical four-parameter macroscopic model is proposed to calculate the "apparent reacted 1O2 concentration", [1O2]rx, as a clinical PDT dosimetry quantity. This model incorporates light diffusion equation and a set of PDT kinetics equations, which can be applied in any clinical treatment geometry. We demonstrate that by introducing a fitting quantity "apparent singlet oxygen threshold concentration" [1O2]rx, sd, it is feasible to determine the model parameters by fitting the computed [1O2]rx to the Photofrin-mediated PDT-induced necrotic distance using interstitially-measured Photofrin concentration and optical properties within each mouse. After determining the model parameters and the [1O2]rx, sd, we expect to use this model as an explicit dosimetry to assess PDT treatment outcome for a specific photosensitizer in an in vivo environment. The results also provide evidence that the [1O2]rx, because it takes into account the oxygen consumption (or light fluence rate) effect, can be a better predictor of PDT outcome than the PDT dose defined as the energy absorbed by the photosensitizer, which is proportional to the product of photosensitizer concentration and light fluence. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Singlet oxygen (1O2) is the major cytotoxic agent responsible for cell killing for type-II photodynamic therapy (PDT). An empirical four-parameter macroscopic model is proposed to calculate the "apparent reacted 1O2 concentration", [1O2]rx, as a clinical PDT dosimetry quantity. This model incorporates light diffusion equation and a set of PDT kinetics equations, which can be applied in any clinical treatment geometry. We demonstrate that by introducing a fitting quantity "apparent singlet oxygen threshold concentration" [1O2]rx, sd, it is feasible to determine the model parameters by fitting the computed [1O2]rx to the Photofrin-mediated PDT-induced necrotic distance using interstitially-measured Photofrin concentration and optical properties within each mouse. After determining the model parameters and the [1O2]rx, sd, we expect to use this model as an explicit dosimetry to assess PDT treatment outcome for a specific photosensitizer in an in vivo environment. The results also provide evidence that the [1O2]rx, because it takes into account the oxygen consumption (or light fluence rate) effect, can be a better predictor of PDT outcome than the PDT dose defined as the energy absorbed by the photosensitizer, which is proportional to the product of photosensitizer concentration and light fluence. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Photodynamic inactivation of bacteria (PDIB) is considered a new approach for the struggle against multiresistant bacteria. To achieve a sufficient level of bacteria killing, the photosensitizer must attach to and/or penetrate the bacteria and generate a sufficiently high amount of singlet oxygen. To optimize PDIB, the direct detection and quantification of singlet oxygen in bacteria is a helpful tool. Singlet-oxygen luminescence is a very weak signal, in particular in living bacteria. We first performed experiments in aqueous photosensitizer solution to optimize the luminescence system. We eliminated non-singlet-oxygen photons, which is important for the quantification of singlet oxygen and its rise and decay rates. This procedure is even more important when the laser excitation beam is scattered by bacteria (diameter 1 [mu]m). In suspensions with both Gram-positive and Gram-negative bacteria we then clearly detected singlet oxygen by its luminescence and determined the respective rise and decay times. The decay times should provide an indication of localization of singlet oxygen and hence of the photosensitizer even in small bacteria. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear optical imaging of human skin and of polychromatic microspheres was carried out to compare and evaluate the imaging properties of three different excitation femtosecond lasers: a spectrally tunable 80 MHz Ti: sapphire oscillator that produced 100 fs pulses (spectral width [sim]10 nm) and two ultrabroadband Ti: sapphire oscillators with repetition rates of 85 MHz and 1 GHz. The latter of these two and the 100 fs laser were combined with a laser scanning microscope (TauMap). The intensities of images of the polychromatic microsphere samples obtained with both lasers are in accordance with the usual dependence of two-photon processes on laser pulse parameters, i.e. the intensity is proportional to the square of the mean laser power and the reciprocal pulse duration. In contrast to that, skin images measured with all three different excitation sources with mean powers of each laser adjusted to the particular pulse length and repetition rate exhibited discrepancies from this relation. For characterization of the ultrabroadband GHz laser, the measurements are supplemented by spectra of second-harmonic-generation signals of urea and collagen. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Light delivery and monitoring during photodynamic therapy (PDT) is often limited by the need for a physical link between the light source, detectors and the treatment volume. This paper reports on the first in vivo experiments performed with a fully implantable telemetric system, designed for a rat glioblastoma model. In this system, light delivery is performed using a solid state optode containing 2 LEDs, and 4 photodiodes which will be used to monitor light delivery in future experiments. Powering and communication is achieved by means of an inductive link. The implant may remain in the animal for extended time periods, making it particularly interesting for performing metronomic PDT. In this paper, we demonstrate the feasibility of in vivo light delivery and biocompatibility of the device.. Activation of the inductive link as well as illumination of the brain by the LED did not influence animal behavior during or after treatment. We show that the implant can remain in the animal for two weeks without causing serious biological reactions. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
The authors have developed a tomographic diffractive microscope that combines microholography with illumination from an angular synthetic aperture. It images specimens relative to their complex index of refraction distribution (index and absorption) and permits imaging of unlabelled specimens, with high lateral resolution. The authors now study its use for biological applications, and imaged several preparations with fluorescence confocal microscopy and tomographic diffractive microscopy. The results highlight some interesting features of this instrument, which should attract the interest of biologists for this new technique. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
The authors recorded the elastic light-scattering pattern of pollen over a large spatial angle range to investigate the potential light scattering for pollen identification. The scattering from elm, hazel, birch, chestnut, willow, sunflower, ragweed and pine was measured. The scattering patterns show distinct differences that can be used for the classification of pollen with simple algorithms. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Applied Optics
Show articles…Giuseppe MolesiniEarly steps tracing back to Galileo's telescope and to the birth of instrumental optics are reported. Particulars of lensmaking technology, basic optics laws, concepts of eye and vision, and issues on instrument trade and service are given. Achievements at the roots of our continuing advances in ... [Appl. Opt. 49, D1-D5 (2010)]
Mumtaz Sheikh, Nabeel A. RizaTo the best of our knowledge, we propose the first motion-free laser beam propagation analyzer with a hybrid design using a digital micromirror device (DMD) and a liquid electronically controlled variable focus lens (ECVFL). Unlike prior analyzers that require profiling the beam at multiple ... [Appl. Opt. 49, D6-D11 (2010)]
Zhiqiang Liu, Takashi Gemma, Joseph Rosen, Mitsuo TakedaAn improved illumination system is proposed for creating a temporally coherent and spatially incoherent extended source to be used for spatial coherence control and reconstruction of a coherent hologram. Taking into account the fact that a rotating ground glass does not behave as an ideal ... [Appl. Opt. 49, D12-D16 (2010)]
Michael HartThe imaging performance of large ground-based astronomical telescopes is compromised by dynamic wavefront aberration caused by atmospheric turbulence. Techniques to measure and correct the aberration in real time, collectively called adaptive optics (AO), have been developed over the past half ... [Appl. Opt. 49, D17-D29 (2010)]
Michael HartThe imaging performance of large ground-based astronomical telescopes is compromised by dynamic wavefront aberration caused by atmospheric turbulence. Techniques to measure and correct the aberration in real time, collectively called adaptive optics (AO), have been developed over the past half ... [Appl. Opt. 49, D17-D29 (2010)]
Zhiqiang Liu, Takashi Gemma, Joseph Rosen, Mitsuo TakedaAn improved illumination system is proposed for creating a temporally coherent and spatially incoherent extended source to be used for spatial coherence control and reconstruction of a coherent hologram. Taking into account the fact that a rotating ground glass does not behave as an ideal ... [Appl. Opt. 49, D12-D16 (2010)]
Mumtaz Sheikh, Nabeel A. RizaTo the best of our knowledge, we propose the first motion-free laser beam propagation analyzer with a hybrid design using a digital micromirror device (DMD) and a liquid electronically controlled variable focus lens (ECVFL). Unlike prior analyzers that require profiling the beam at multiple ... [Appl. Opt. 49, D6-D11 (2010)]
Giuseppe MolesiniEarly steps tracing back to Galileo's telescope and to the birth of instrumental optics are reported. Particulars of lensmaking technology, basic optics laws, concepts of eye and vision, and issues on instrument trade and service are given. Achievements at the roots of our continuing advances in ... [Appl. Opt. 49, D1-D5 (2010)]
Alexander A. Bol'shakov, Jong H. Yoo, Chunyi Liu, John R. Plumer, Richard E. RussoLaser-induced breakdown spectroscopy (LIBS) offers rapid, localized chemical analysis of solid or liquid materials with high spatial resolution in lateral and depth profiling, without the need for sample preparation. Principal component analysis and partial least squares algorithms were applied to ... [Appl. Opt. 49, C132-C142 (2010)]
http://www.opticsinfobase.org/abstract.cfm?URI=ao-49-13-C132
Yuji Ikeda, Ahsa Moon, Masashi KanekoWe propose microwave-enhanced spark-induced breakdown spectroscopy with the same measurement and analysis processes as in laser-induced breakdown spectroscopy, but with a different plasma generation mechanism. The size and lifetime of the plasma generated can contribute to increased measurement ... [Appl. Opt. 49, C95-C100 (2010)]
Biophysical Journal - Table of Contents - Volume 97 Issue 7, 07 October 2009
Show articles…Ingunn W. Jolma, Xiao Yu Ni, Ludger Rensing, Peter Ruoff. Homeostatic mechanisms are essential for the protection and adaptation of organisms in a changing and challenging environment. Previously, we have described molecular mechanisms that lead to robus....
André Berndt, Matthias Prigge, Dietrich Gradmann, Peter Hegemann. Channelrhodopsins are light-gated ion channels that mediate vision in phototactic green algae like Chlamydomonas. In neurosciences, channelrhodopsins are widely used to light-trigger action....
Rocio K. Finol-Urdaneta, Jeffrey R. McArthur, Peter F. Juranka, Robert J. French, Catherine E. Morris. The actions of alcohols and anesthetics on ion channels are poorly understood. Controversy continues about whether bilayer restructuring is relevant to the modulatory effects of these surface acti....
Yuji Karashima, Jean Prenen, Karel Talavera, Annelies Janssens, Thomas Voets, Bernd Nilius. The Ca2+-permeable cation channel TRPA1 acts as an ionotropic receptor for various pungent compounds and as a noxious cold sensor in sensory neurons. It is unclear what proportion of th....
Nilmadhab Chakrabarti, Chris Neale, Jian Payandeh, Emil F. Pai, Régis Pomès. Magnesium translocation across cell membranes is essential for numerous physiological processes. Three recently reported crystal structures of the CorA magnesium transport system revealed a surpri....
Hillary L. Smith, Joseph Hickey, Michael S. Jablin, Antoinette Trujillo, James P. Freyer, Jaroslaw Majewski. Neutron reflectometry (NR) was used to examine live mouse fibroblast cells adherent on a quartz substrate in a deuterated phosphate-buffered saline environment at room temperature. These measureme....
Diana Morozova, Matthias Weiss. Acylation is a frequent means to ensure membrane association of a variety of soluble proteins in living cells. However, many transmembrane proteins are palmitoylated, indicating that this posttran....
Maryam Sayadi, Seiichiro Tanizaki, Michael Feig. The conformational sampling of monomeric, membrane-bound phospholamban is described from computer simulations. Phospholamban (PLB) plays a key role as a regulator of sarcoplasmic reticulum calcium....
John Oreopoulos, Raquel F. Epand, Richard M. Epand, Christopher M. Yip. Direct visualization of the mechanism(s) by which peptides induce localized changes to the structure of membranes has high potential for enabling understanding of the structure-function relationsh....
Christophe Bécavin, Maria Barbi, Jean-Marc Victor, Annick Lesne. During eukaryotic transcription, RNA-polymerase activity generates torsional stress in DNA, having a negative impact on the elongation process. Using our previous studies of chromatin fiber struct....
Maria Mills, Brad Orr, Mark M. Banaszak Holl, Ioan Andricioaei. The mechanism of DNA compaction by dendrimers is key to the design of nanotechnologies that can deliver genetic material into cells. We present atomistic simulations, mesoscopic modeling and singl....
Christopher A. Waudby, Tuomas P.J. Knowles, Glyn L. Devlin, Jeremy N. Skepper, Heath Ecroyd, John A. Carver, Mark E. Welland, John Christodoulou, Christopher M. Dobson, Sarah Meehan. αB-Crystallin is a small heat-shock protein (sHsp) that is colocalized with α-synuclein (αSyn) in Lewy bodies—the pathological hallmarks of Parkinson's disease—and is an inhibitor of....
Derek Jantz, Jeremy M. Berg. Engineered transcription factors and endonucleases based on designed Cys2His2 zinc finger domains have proven to be effective tools for the directed regulation and modificati....
Antonija Kuzmanic, Bojan Zagrovic. Root mean-square deviation (RMSD) after roto-translational least-squares fitting is a measure of global structural similarity of macromolecules used commonly. On the other hand, experimental x-ray....
Boris Aguilar, Ramu Anandakrishnan, Jory Z. Ruscio, Alexey V. Onufriev. This work investigates statistical prevalence and overall physical origins of changes in charge states of receptor proteins upon ligand binding. These changes are explored as a function of the lig....
Eduard V. Bocharov, Maxim L. Mayzel, Pavel E. Volynsky, Konstantin S. Mineev, Elena N. Tkach, Yaroslav S. Ermolyuk, Alexey A. Schulga, Roman G. Efremov, Alexander S. Arseniev. The Eph receptor tyrosine kinases and their membrane-bound ephrin ligands control a diverse array of cell-cell interactions in the developing and adult organisms. During signal transduction across....
Ernesto Estrada. Residue networks representing 595 nonhomologous proteins are studied. These networks exhibit universal topological characteristics as they belong to the topological class of modular networks forme....
Cen Gao, Min-Sun Park, Harry A. Stern. The conformation adopted by a ligand on binding to a receptor may differ from its lowest-energy conformation in solution. In addition, the bound ligand is more conformationally restricted, which i....
A. Celli, S. Sanchez, M. Behne, T. Hazlett, E. Gratton, T. Mauro. Ionic gradients are found across a variety of tissues and organs. In this report, we apply the phasor representation of fluorescence lifetime imaging data to the quantitative study of ionic concen....
Bart van Oort, Marieke Alberts, Silvia de Bianchi, Luca Dall'Osto, Roberto Bassi, Gediminas Trinkunas, Roberta Croce, Herbert van Amerongen. The role of individual photosynthetic antenna complexes of Photosystem II (PSII) both in membrane organization and excitation energy transfer have been investigated. Thylakoid membranes from wild-....
Jiahn-Haur Liao, Yu-Ching Lin, Jowey Hsu, Alan Yueh-Luen Lee, Tse-An Chen, Chun-Hua Hsu, Jiun-Ly Chir, Kuo-Feng Hua, Tzu-Hua Wu, Li-Jenn Hong, Pei-Wen Yen, Arthur Chiou, Shih-Hsiung Wu.
The Journal of Biomedical Optics is intended to be the repository for peer-reviewed papers that utilize modern optical technology for improved health care and biomedical research. Topics suitable for the Journal of Biomedical Optics include the following: medical and biological imaging instrumentation and techniques; noninvasive physiological monitoring; laser-tissue interactions and dosimetry; laser diagnostic and laser therapeutic methods, instruments, and systems; ophthalmic instruments, systems, implants, and clinical applications; optical biosensors; ultrasensitive detection and optical clinical chemistry; optical tomography and photon migration; endoscopic systems and applications; biospectroscopy and optoelectronic instrumentation; fiber optic sensors, instrumentation, and techniques; optical and structural microscopy; applications of optical systems and technologies to biology and medicine.
Show articles…Parag V. Chitnis, Hans-Peter Brecht, Richard Su et al. A 3-D optoacoustic imaging system was used to visualize thermal lesions produced in vivo using high-intensity focused ultrasound (HIFU). A 7.5-MHz, surgical, focused transducer with a radius of curvature of 35 mm and an aperture diameter of 23 mm was used to generate HIFU. A pulsed laser, which co ... [J. Biomed. Opt. 15, 021313 (2010)] published Thu Mar 11, 2010.
Baohong Yuan and Yuan Liu We report experimentally observed ultrasound-modulated fluorescence (UMF) from a submillimeter tube filled with rhodamine B aqueous solution. The tube was submerged in water and a scattering medium. Based on the measured data, we find that the UMF signals might be generated from three mechanisms: mo ... [J. Biomed. Opt. 15, 021321 (2010)] published Thu Mar 11, 2010.
Robert Nuster, Markus Holotta, Christian Kremser et al. A device for three-dimensional (3-D) photoacoustic tomography with resolution in the range of tens of micrometers is presented that uses a light beam for interferometric detection of acoustic waves. Reconstruction of the 3-D initial pressure distribution from the signals representing line integrals ... [J. Biomed. Opt. 15, 021307 (2010)] published Thu Mar 11, 2010.
Jing Wang, Tan Liu, Shuliang Jiao et al. We investigate the saturation effect, which describes the violation of the linearity between the measured photoacoustic amplitude and the object's optical absorption coefficient in functional photoacoustic imaging when the optical absorption in the object increases. We model the optical energy depos ... [J. Biomed. Opt. 15, 021317 (2010)] published Thu Mar 11, 2010.
Liang Song, Konstantin Maslov, K. Kirk Shung et al. With a refined ultrasound-array-based real-time photoacoustic microscopy (UA-PAM) system, we demonstrate the feasibility of noninvasive in vivo imaging of human pulsatile dynamics. The system, capable of real-time B-scan imaging at 50 Hz and high-speed 3-D imaging, is validated by imaging the subcu ... [J. Biomed. Opt. 15, 021303 (2010)] published Thu Mar 11, 2010.
Liang Song, Konstantin Maslov, K. Kirk Shung et al. With a refined ultrasound-array-based real-time photoacoustic microscopy (UA-PAM) system, we demonstrate the feasibility of noninvasive in vivo imaging of human pulsatile dynamics. The system, capable of real-time B-scan imaging at 50 Hz and high-speed 3-D imaging, is validated by imaging the subcu ... [J. Biomed. Opt. 15, 021303 (2010)] published Thu Mar 11, 2010.
Jing Wang, Tan Liu, Shuliang Jiao et al. We investigate the saturation effect, which describes the violation of the linearity between the measured photoacoustic amplitude and the object's optical absorption coefficient in functional photoacoustic imaging when the optical absorption in the object increases. We model the optical energy depos ... [J. Biomed. Opt. 15, 021317 (2010)] published Thu Mar 11, 2010.
Robert Nuster, Markus Holotta, Christian Kremser et al. A device for three-dimensional (3-D) photoacoustic tomography with resolution in the range of tens of micrometers is presented that uses a light beam for interferometric detection of acoustic waves. Reconstruction of the 3-D initial pressure distribution from the signals representing line integrals ... [J. Biomed. Opt. 15, 021307 (2010)] published Thu Mar 11, 2010.
Baohong Yuan and Yuan Liu We report experimentally observed ultrasound-modulated fluorescence (UMF) from a submillimeter tube filled with rhodamine B aqueous solution. The tube was submerged in water and a scattering medium. Based on the measured data, we find that the UMF signals might be generated from three mechanisms: mo ... [J. Biomed. Opt. 15, 021321 (2010)] published Thu Mar 11, 2010.
Parag V. Chitnis, Hans-Peter Brecht, Richard Su et al. A 3-D optoacoustic imaging system was used to visualize thermal lesions produced in vivo using high-intensity focused ultrasound (HIFU). A 7.5-MHz, surgical, focused transducer with a radius of curvature of 35 mm and an aperture diameter of 23 mm was used to generate HIFU. A pulsed laser, which co ... [J. Biomed. Opt. 15, 021313 (2010)] published Thu Mar 11, 2010.
Nature Photonics offers a unique mix of news and reviews alongside top-quality research papers. Published monthly, in print and online, the journal reflects the entire spectrum of photonics and optics.
Show articles…Japan's new government has reversed its decision for research funding and angered many scientists in the process as budgets — including those for photonics research — get cut.
http://feeds.nature.com/~r/nphoton/rss/current/~3/LR4TuYK7ETI/nphoton.2009.275
The use of pulse-shaping technology to optimize the temporal and spectral properties of ultrashort light pulses can enhance their utility in many applications.
http://feeds.nature.com/~r/nphoton/rss/current/~3/2GRjXAfnr_Y/nphoton.2010.22
Cameras equipped with an image intensifier make it possible to image ultrafast and low-light events and are proving of particular importance for combustion studies.
http://feeds.nature.com/~r/nphoton/rss/current/~3/mnerQB9p55Q/nphoton.2010.21
Table-top sources that generate both extreme ultraviolet light and soft X-rays through high-harmonic generation of ultrafast infrared laser pulses look set to perform tasks previously accessible using only large-scale synchrotrons.
http://feeds.nature.com/~r/nphoton/rss/current/~3/e9urXCmY5-Q/nphoton.2010.20
Researchers in Germany have set up a company to manufacture custom-made optics for ultrafast applications. Nadya Anscombe finds out about the company's products and its plans for the future.
http://feeds.nature.com/~r/nphoton/rss/current/~3/5Hx53x5-du4/nphoton.2010.19
Nature is the international weekly journal of science: a magazine style journal that publishes full-length research papers in all disciplines of science, as well as News and Views, reviews, news, features, commentaries, web focuses and more, covering all branches of science and how science impacts upon all aspects of society and life.
Show articles…Gene expression is an important phenotype that informs about genetic and environmental effects on cellular state. Many studies have previously identified genetic variants for gene expression phenotypes using custom and commercially available microarrays. Second generation sequencing technologies are now providing unprecedented access to the fine structure of the transcriptome. We have sequenced the mRNA fraction of the transcriptome in 60 extended HapMap individuals of European descent and have combined these data with genetic variants from the HapMap3 project. We have quantified exon abundance based on read depth and have also developed methods to quantify whole transcript abundance. We have found that approximately 10 million reads of sequencing can provide access to the same dynamic range as arrays with better quantification of alternative and highly abundant transcripts. Correlation with SNPs (small nucleotide polymorphisms) leads to a larger discovery of eQTLs (expression quantitative trait loci) than with arrays. We also detect a substantial number of variants that influence the structure of mature transcripts indicating variants responsible for alternative splicing. Finally, measures of allele-specific expression allowed the identification of rare eQTLs and allelic differences in transcript structure. This analysis shows that high throughput sequencing technologies reveal new properties of genetic effects on the transcriptome and allow the exploration of genetic effects in cellular processes.
http://feeds.nature.com/~r/nature/rss/aop/~3/QtfnjDsJVbg/nature08903
Understanding the genetic mechanisms underlying natural variation in gene expression is a central goal of both medical and evolutionary genetics, and studies of expression quantitative trait loci (eQTLs) have become an important tool for achieving this goal. Although all eQTL studies so far have assayed messenger RNA levels using expression microarrays, recent advances in RNA sequencing enable the analysis of transcript variation at unprecedented resolution. We sequenced RNA from 69 lymphoblastoid cell lines derived from unrelated Nigerian individuals that have been extensively genotyped by the International HapMap Project. By pooling data from all individuals, we generated a map of the transcriptional landscape of these cells, identifying extensive use of unannotated untranslated regions and more than 100 new putative protein-coding exons. Using the genotypes from the HapMap project, we identified more than a thousand genes at which genetic variation influences overall expression levels or splicing. We demonstrate that eQTLs near genes generally act by a mechanism involving allele-specific expression, and that variation that influences the inclusion of an exon is enriched within and near the consensus splice sites. Our results illustrate the power of high-throughput sequencing for the joint analysis of variation in transcription, splicing and allele-specific expression across individuals.
http://feeds.nature.com/~r/nature/rss/aop/~3/wBMjoMeKcJ0/nature08872
Domestic animals are excellent models for genetic studies of phenotypic evolution. They have evolved genetic adaptations to a new environment, the farm, and have been subjected to strong human-driven selection leading to remarkable phenotypic changes in morphology, physiology and behaviour. Identifying the genetic changes underlying these developments provides new insight into general mechanisms by which genetic variation shapes phenotypic diversity. Here we describe the use of massively parallel sequencing to identify selective sweeps of favourable alleles and candidate mutations that have had a prominent role in the domestication of chickens (Gallus gallus domesticus) and their subsequent specialization into broiler (meat-producing) and layer (egg-producing) chickens. We have generated 44.5-fold coverage of the chicken genome using pools of genomic DNA representing eight different populations of domestic chickens as well as red jungle fowl (Gallus gallus), the major wild ancestor. We report more than 7,000,000 single nucleotide polymorphisms, almost 1,300 deletions and a number of putative selective sweeps. One of the most striking selective sweeps found in all domestic chickens occurred at the locus for thyroid stimulating hormone receptor (TSHR), which has a pivotal role in metabolic regulation and photoperiod control of reproduction in vertebrates. Several of the selective sweeps detected in broilers overlapped genes associated with growth, appetite and metabolic regulation. We found little evidence that selection for loss-of-function mutations had a prominent role in chicken domestication, but we detected two deletions in coding sequences that we suggest are functionally important. This study has direct application to animal breeding and enhances the importance of the domestic chicken as a model organism for biomedical research.
http://feeds.nature.com/~r/nature/rss/aop/~3/TizJLa3UK2U/nature08832
The relationship between the genotype and the phenotype, or the genotype–phenotype map, is generally approached with the tools of multivariate quantitative genetics and morphometrics. Whereas studies of development and mathematical models of development may offer new insights into the genotype–phenotype map, the challenge is to make them useful at the level of microevolution. Here we report a computational model of mammalian tooth development that combines parameters of genetic and cellular interactions to produce a three-dimensional tooth from a simple tooth primordia. We systematically tinkered with each of the model parameters to generate phenotypic variation and used geometric morphometric analyses to identify, or developmentally ordinate, parameters best explaining population-level variation of real teeth. To model the full range of developmentally possible morphologies, we used a population sample of ringed seals (Phoca hispida ladogensis). Seal dentitions show a high degree of variation, typically linked to the lack of exact occlusion. Our model suggests that despite the complexity of development and teeth, there may be a simple basis for dental variation. Changes in single parameters regulating signalling during cusp development may explain shape variation among individuals, whereas a parameter regulating epithelial growth may explain serial, tooth-to-tooth variation along the jaw. Our study provides a step towards integrating the genotype, development and the phenotype.
http://feeds.nature.com/~r/nature/rss/aop/~3/wiObwaoiULQ/nature08838
Acquisition of cell identity in plants relies strongly on positional information, hence cell–cell communication and inductive signalling are instrumental for developmental patterning. During Arabidopsis embryogenesis, an extra-embryonic cell is specified to become the founder cell of the primary root meristem, hypophysis, in response to signals from adjacent embryonic cells. The auxin-dependent transcription factor MONOPTEROS (MP) drives hypophysis specification by promoting transport of the hormone auxin from the embryo to the hypophysis precursor. However, auxin accumulation is not sufficient for hypophysis specification, indicating that additional MP-dependent signals are required. Here we describe the microarray-based isolation of MP target genes that mediate signalling from embryo to hypophysis. Of three direct transcriptional target genes, TARGET OF MP 5 (TMO5) and TMO7 encode basic helix–loop–helix (bHLH) transcription factors that are expressed in the hypophysis-adjacent embryo cells, and are required and partially sufficient for MP-dependent root initiation. Importantly, the small TMO7 transcription factor moves from its site of synthesis in the embryo to the hypophysis precursor, thus representing a novel MP-dependent intercellular signal in embryonic root specification.
http://feeds.nature.com/~r/nature/rss/aop/~3/mBoJwhWDj94/nature08836
Acquisition of cell identity in plants relies strongly on positional information, hence cell–cell communication and inductive signalling are instrumental for developmental patterning. During Arabidopsis embryogenesis, an extra-embryonic cell is specified to become the founder cell of the primary root meristem, hypophysis, in response to signals from adjacent embryonic cells. The auxin-dependent transcription factor MONOPTEROS (MP) drives hypophysis specification by promoting transport of the hormone auxin from the embryo to the hypophysis precursor. However, auxin accumulation is not sufficient for hypophysis specification, indicating that additional MP-dependent signals are required. Here we describe the microarray-based isolation of MP target genes that mediate signalling from embryo to hypophysis. Of three direct transcriptional target genes, TARGET OF MP 5 (TMO5) and TMO7 encode basic helix–loop–helix (bHLH) transcription factors that are expressed in the hypophysis-adjacent embryo cells, and are required and partially sufficient for MP-dependent root initiation. Importantly, the small TMO7 transcription factor moves from its site of synthesis in the embryo to the hypophysis precursor, thus representing a novel MP-dependent intercellular signal in embryonic root specification.
http://feeds.nature.com/~r/nature/rss/aop/~3/mBoJwhWDj94/nature08836
The relationship between the genotype and the phenotype, or the genotype–phenotype map, is generally approached with the tools of multivariate quantitative genetics and morphometrics. Whereas studies of development and mathematical models of development may offer new insights into the genotype–phenotype map, the challenge is to make them useful at the level of microevolution. Here we report a computational model of mammalian tooth development that combines parameters of genetic and cellular interactions to produce a three-dimensional tooth from a simple tooth primordia. We systematically tinkered with each of the model parameters to generate phenotypic variation and used geometric morphometric analyses to identify, or developmentally ordinate, parameters best explaining population-level variation of real teeth. To model the full range of developmentally possible morphologies, we used a population sample of ringed seals (Phoca hispida ladogensis). Seal dentitions show a high degree of variation, typically linked to the lack of exact occlusion. Our model suggests that despite the complexity of development and teeth, there may be a simple basis for dental variation. Changes in single parameters regulating signalling during cusp development may explain shape variation among individuals, whereas a parameter regulating epithelial growth may explain serial, tooth-to-tooth variation along the jaw. Our study provides a step towards integrating the genotype, development and the phenotype.
http://feeds.nature.com/~r/nature/rss/aop/~3/wiObwaoiULQ/nature08838
Domestic animals are excellent models for genetic studies of phenotypic evolution. They have evolved genetic adaptations to a new environment, the farm, and have been subjected to strong human-driven selection leading to remarkable phenotypic changes in morphology, physiology and behaviour. Identifying the genetic changes underlying these developments provides new insight into general mechanisms by which genetic variation shapes phenotypic diversity. Here we describe the use of massively parallel sequencing to identify selective sweeps of favourable alleles and candidate mutations that have had a prominent role in the domestication of chickens (Gallus gallus domesticus) and their subsequent specialization into broiler (meat-producing) and layer (egg-producing) chickens. We have generated 44.5-fold coverage of the chicken genome using pools of genomic DNA representing eight different populations of domestic chickens as well as red jungle fowl (Gallus gallus), the major wild ancestor. We report more than 7,000,000 single nucleotide polymorphisms, almost 1,300 deletions and a number of putative selective sweeps. One of the most striking selective sweeps found in all domestic chickens occurred at the locus for thyroid stimulating hormone receptor (TSHR), which has a pivotal role in metabolic regulation and photoperiod control of reproduction in vertebrates. Several of the selective sweeps detected in broilers overlapped genes associated with growth, appetite and metabolic regulation. We found little evidence that selection for loss-of-function mutations had a prominent role in chicken domestication, but we detected two deletions in coding sequences that we suggest are functionally important. This study has direct application to animal breeding and enhances the importance of the domestic chicken as a model organism for biomedical research.
http://feeds.nature.com/~r/nature/rss/aop/~3/TizJLa3UK2U/nature08832
Understanding the genetic mechanisms underlying natural variation in gene expression is a central goal of both medical and evolutionary genetics, and studies of expression quantitative trait loci (eQTLs) have become an important tool for achieving this goal. Although all eQTL studies so far have assayed messenger RNA levels using expression microarrays, recent advances in RNA sequencing enable the analysis of transcript variation at unprecedented resolution. We sequenced RNA from 69 lymphoblastoid cell lines derived from unrelated Nigerian individuals that have been extensively genotyped by the International HapMap Project. By pooling data from all individuals, we generated a map of the transcriptional landscape of these cells, identifying extensive use of unannotated untranslated regions and more than 100 new putative protein-coding exons. Using the genotypes from the HapMap project, we identified more than a thousand genes at which genetic variation influences overall expression levels or splicing. We demonstrate that eQTLs near genes generally act by a mechanism involving allele-specific expression, and that variation that influences the inclusion of an exon is enriched within and near the consensus splice sites. Our results illustrate the power of high-throughput sequencing for the joint analysis of variation in transcription, splicing and allele-specific expression across individuals.
http://feeds.nature.com/~r/nature/rss/aop/~3/wBMjoMeKcJ0/nature08872
Gene expression is an important phenotype that informs about genetic and environmental effects on cellular state. Many studies have previously identified genetic variants for gene expression phenotypes using custom and commercially available microarrays. Second generation sequencing technologies are now providing unprecedented access to the fine structure of the transcriptome. We have sequenced the mRNA fraction of the transcriptome in 60 extended HapMap individuals of European descent and have combined these data with genetic variants from the HapMap3 project. We have quantified exon abundance based on read depth and have also developed methods to quantify whole transcript abundance. We have found that approximately 10 million reads of sequencing can provide access to the same dynamic range as arrays with better quantification of alternative and highly abundant transcripts. Correlation with SNPs (small nucleotide polymorphisms) leads to a larger discovery of eQTLs (expression quantitative trait loci) than with arrays. We also detect a substantial number of variants that influence the structure of mature transcripts indicating variants responsible for alternative splicing. Finally, measures of allele-specific expression allowed the identification of rare eQTLs and allelic differences in transcript structure. This analysis shows that high throughput sequencing technologies reveal new properties of genetic effects on the transcriptome and allow the exploration of genetic effects in cellular processes.
http://feeds.nature.com/~r/nature/rss/aop/~3/QtfnjDsJVbg/nature08903
Nature is the international weekly journal of science: a magazine style journal that publishes full-length research papers in all disciplines of science, as well as News and Views, reviews, news, features, commentaries, web focuses and more, covering all branches of science and how science impacts upon all aspects of society and life.
Show articles…The last quarter of the twentieth century and the beginning decade of the twenty-first witnessed spectacular discoveries in the chemistry of the heavier main-group elements. The new compounds that were synthesized highlighted the fundamental differences between their electronic properties and those of the lighter elements to a degree that was not previously apparent. This has led to new structural and bonding insights as well as a gradually increasing realization that the chemistry of the heavier main-group elements more resembles that of transition-metal complexes than that of their lighter main-group congeners. The similarity is underlined by recent work, which has shown that many of the new compounds react with small molecules such as H2, NH3, C2H4 or CO under mild conditions and display potential for applications in catalysis.
http://feeds.nature.com/~r/nature/rss/current/~3/41zpF0g0t3c/nature08634
Over the past several decades, quantum information science has emerged to seek answers to the question: can we gain some advantage by storing, transmitting and processing information encoded in systems that exhibit unique quantum properties? Today it is understood that the answer is yes, and many research groups around the world are working towards the highly ambitious technological goal of building a quantum computer, which would dramatically improve computational power for particular tasks. A number of physical systems, spanning much of modern physics, are being developed for quantum computation. However, it remains unclear which technology, if any, will ultimately prove successful. Here we describe the latest developments for each of the leading approaches and explain the major challenges for the future.
http://feeds.nature.com/~r/nature/rss/current/~3/jSY_Sp3u-Z8/nature08812
Optics Express
Show articles…Antonio García-Zambrana, Carmen Castillo-Vázquez, Beatriz Castillo-VázquezAtmospheric turbulence produces fluctuations in the irradiance of the transmitted optical beam, which is known as atmospheric scintillation, severely degrading the link performance. In this paper, a scheme combining transmit laser selection (TLS) and space-time trellis code (STTC) for ... [Opt. Express 18, 5356-5366 (2010)]
Song-Jin Im, Anton Husakou, Joachim HerrmannWe theoretically study a novel approach for soliton-induced high-power supercontinuum generation by using kagome lattice HC-PCFs filled with a noble gas. Anomalous dispersion and broad-band low loss of these fibers enable the generation of two-octave broad spectra by fs pulses, with high coherence ... [Opt. Express 18, 5367-5374 (2010)]
L. Sun, S. Jiang, J. R. MarcianteAn all-fiber optical magnetic field sensor is demonstrated. It consists of a fiber Faraday rotator and a fiber polarizer. The fiber Faraday rotator uses a 2-cm-long section of 56-wt.%-terbium–doped silicate fiber with a Verdet constant of –24.5 rad/(Tm) at 1053 nm. The fiber polarizer ... [Opt. Express 18, 5407-5412 (2010)]
C. M. Wynn, S. Palmacci, R. R. Kunz, M. RothschildNoncontact detection of the homemade explosive constituents urea nitrate, nitromethane and ammonium nitrate is achieved using photodissociation followed by laser-induced fluorescence (PD-LIF). Our technique utilizes a single ultraviolet laser pulse (~7 ns) to vaporize and photodissociate the ... [Opt. Express 18, 5399-5406 (2010)]
Jesse D. McMullen, Warren R. ZipfelWe present a de novo design of an objective for use in multi-photon (MPM) and second harmonic generation (SHG) microscopy. This objective was designed to have a large field of view (FOV), while maintaining a moderate numerical aperture (NA) and relative straight forward construction. A dichroic ... [Opt. Express 18, 5390-5398 (2010)]
Teun-Teun Kim, Sun-Goo Lee, Hae Yong Park, Jae-Eun Kim, Chul-Sik KeeA two-dimensional photonic crystal asymmetric Mach-Zehnder filter (AMZF) based on the self-collimation effect is studied by numerical simulations and experimental measurements in microwave region. A self-collimated beam is effectively controlled by employing line-defect beam splitters and mirrors. ... [Opt. Express 18, 5384-5389 (2010)]
Zhaofeng Li, Humeyra Caglayan, Evrim Colak, Jiangfeng Zhou, Costas M. Soukoulis, Ekmel OzbayA pair of mutually twisted metallic cross-wires can produce giant optical activity. When this single chiral layer is stacked layer by layer in order to build a thick chiral metamaterial, strong coupling effects are found between the two adjacent chiral layers. We studied these coupling effects ... [Opt. Express 18, 5375-5383 (2010)]
X. Han, F. Fusari, M. D. Serrano, A. A. Lagatsky, J. M. Cano-Torres, C. T. A. Brown, C. Zaldo, W. SibbettTetragonal single crystals of NaT(WO_4)_2 (T = Y or Lu) co-doped with Tm^3+ and Ho^3+ ions have been employed for broadly tunable and efficient room-temperature laser operation at around 2 μm. With Ti:sapphire laser pumping at 795 nm, a slope efficiency and a maximum output power as high as ... [Opt. Express 18, 5413-5419 (2010)]
Tao Xu, Ning Zhu, Michelle Y.-C. Xu, Lech Wosinski, J. Stewart Aitchison, H. E. RudaAn optical microcavity based on pillar arrays has been fabricated in Si/SiO_2 material system. Transmission measurement was taken and a quality factor as high as 27,600 was observed. This cavity was tested for sensing applications by immersing into optical fluids with accurate refractive ... [Opt. Express 18, 5420-5425 (2010)]
Kang Kang Chen, Shaif-ul Alam, Jonathan H. V. Price, John R. Hayes, Dejiao Lin, Andrew Malinowski, Christophe Codemard, Debashri Ghosh, Mrinmay Pal, Shyamal K. Bhadra, David J. RichardsonWe report a picosecond fiber MOPA pumped supercontinuum source with 39 W output, spanning at least 0.4-2.25 µm at a repetition rate of 114.8 MHz. The 2m long PCF had a large, 4.4 µm diameter core and a high-delta design which led to an 80% coupling efficiency, high damage threshold and ... [Opt. Express 18, 5426-5432 (2010)]
Cèlia Blain, Rodolphe Conan, Colin Bradley, Olivier GuyonNew astronomical challenges revolve around the observation of faint galaxies, nearby star-forming regions and the direct imaging of exoplanets. The technologies required to progress in these fields of research rely on the development of custom Adaptive Optics (AO) instruments such as ... [Opt. Express 18, 5433-5448 (2010)]
Marta Quintanilla, Emma Martín Rodríguez, Eugenio Cantelar, Fernando Cussó, Concepción DomingoIn this work micro-Raman scattering experiments have been performed in LiNbO_3:Tm^3+ samples with waveguides fabricated by Zn^2+ in-diffusion. The results shown that Zn^2+ ions enter the lattice in Li^+ sites, but also in interstitial positions. This produces a compaction of the lattice close to ... [Opt. Express 18, 5449-5458 (2010)]
Wook-Jae Lee, Jae-Eun Kim, Hae Yong Park, Myung-Hyun LeeSilver lenses having super-resolution are analyzed in terms of antisymmetric modes of surface plasmon which have the ability to amplify evanescent waves in UV region. Antisymmetric surface plasmon modes excited by subwavelength grating enhances the resolution and contrast of silver superlens. ... [Opt. Express 18, 5459-5465 (2010)]
Jun Ho Son, Jong-Lam LeeWe present a method of increasing light output power and suppressing efficiency droop in vertical-structure InGaN/GaN MQW LEDs without modifying their epitaxial layers. These improvements are achieved by reducing the quantum-confined Stark effect (QCSE) by reducing piezoelectric polarization that ... [Opt. Express 18, 5466-5471 (2010)]
Shanshan Song, Janesha Dua, Craig B. ArnoldSpin-coating of chalcogenide glass is a low-cost, scalable method to create optical grade thin films, which are ideal for visible and infrared applications. In this paper, we study the influence of annealing on optical parameters of As_2S_3 films by examining UV-visible and infrared spectroscopy ... [Opt. Express 18, 5472-5480 (2010)]
Jo Gjessing, Erik Stensrud Marstein, Aasmund SudbøLight-trapping techniques can be used to improve the efficiency of thin silicon solar cells. We report on numerical investigation of a light trapping design consisting of a 2D back-side diffraction grating in combination with an aluminum mirror and a spacing layer of low permittivity to minimize ... [Opt. Express 18, 5481-5495 (2010)]
Shujing Liu, Long Jin, Wei Jin, Dongning Wang, Changrui Liao, Ying WangWe present a new method for fabricating structural long-period gratings (LPGs) in photonic-crystal fibers (PCFs). The method is based on periodically drilling holes into the PCF cladding along the length of the fiber by use of a focused femtosecond infrared laser. A very short LPG with only 9 ... [Opt. Express 18, 5496-5503 (2010)]
Yongjin Wang, Fangren Hu, Yoshiaki Kanamori, Tong Wu, Kazuhiro HaneWe propose, fabricate and characterize the freestanding GaN nanocolumn membrane with bottom subwavelength nanostructures. The GaN nanocolumns are epitaxially grown on freestanding nanostructured silicon substrate that is achieved by a combination of self-assemble technique and silicon-on-insulator ... [Opt. Express 18, 5504-5511 (2010)]
Kunihito Hirano, Taiki Yamazaki, Shinichiro Morikatsu, Haruka Okumura, Hiroki Aida, Atsushi Uchida, Shigeru Yoshimori, Kazuyuki Yoshimura, Takahisa Harayama, Peter DavisWe experimentally demonstrate random bit generation using multi-bit samples of bandwidth-enhanced chaos in semiconductor lasers. Chaotic fluctuation of laser output is generated in a semiconductor laser with optical feedback and the chaotic output is injected into a second semiconductor laser to ... [Opt. Express 18, 5512-5524 (2010)]
Nicholas P. Sergeant, Mukul Agrawal, Peter PeumansSpectral control of the emissivity of surfaces is essential for efficient conversion of solar radiation into heat. We investigated surfaces consisting of sub-wavelength V-groove gratings coated with aperiodic metal-dielectric stacks. The spectral behavior of the coated gratings was modeled using ... [Opt. Express 18, 5525-5540 (2010)]
R. P. Giddings, X. Q. Jin, E. Hugues-Salas, E. Giacoumidis, J. L. Wei, J. M. TangThe fastest ever 11.25Gb/s real-time FPGA-based optical orthogonal frequency division multiplexing (OOFDM) transceivers utilizing 64-QAM encoding/decoding and significantly improved variable power loading are experimentally demonstrated, for the first time, incorporating advanced functionalities of ... [Opt. Express 18, 5541-5555 (2010)]
Anthony Kim, Mathieu Roy, Farhan Dadani, Brian C. WilsonMeasurement of tissue optical absorption and (transport) reduced scattering coefficients (μ_a and μ_s', respectively) is fundamental to many applications of light in medicine and biology. We report a handheld fiberoptic probe to determine these coefficients by measuring the diffuse ... [Opt. Express 18, 5580-5594 (2010)]
Christian Wiegand, Michael Herrmann, Sebastian Bachtler, Jens Klier, Daniel Molter, Joachim Jonuscheit, René BeigangWe present a pulsed THz Imaging System with a line focus intended to speed up measurements. A balanced 1-D detection scheme working with two industrial line-scan cameras is used. The instrument is implemented without the need for an amplified laser system, increasing the industrial applicability. ... [Opt. Express 18, 5595-5601 (2010)]
Alistair Gorman, David William Fletcher-Holmes, Andrew Robert HarveyA snapshot multi-spectral imaging technique is described which employs multiple cascaded birefringent interferometers to simultaneously spectrally filter and demultiplex multiple spectral images onto a single detector array. Spectral images are recorded directly without the need for inversion and ... [Opt. Express 18, 5602-5608 (2010)]
Oscar G. Rodríguez-Herrera, David Lara, Chris DaintyWe present a system built to perform measurements of scattering-angle-resolved polarization state distributions across the exit pupil of a high numerical aperture collector lens. These distributions contain information about the three-dimensional electromagnetic field that results from the ... [Opt. Express 18, 5609-5628 (2010)]
Fang-Wen Sheu, Hong-Yu Wu, Sy-Hann ChenWe exploit a fiber puller to transform a telecom single-mode optical fiber with a 125 µm diameter into a symmetric and unbroken slightly tapered optical fiber with a 50 µm diameter at the minimum waist. When the laser light is launched into the optical fiber, we can observe that, due to ... [Opt. Express 18, 5574-5579 (2010)]
Kam Wai C. Chan, Malcolm N. O'Sullivan, Robert W. BoydWe compare the performance of high-order thermal ghost imaging with that of conventional (that is, lowest-order) thermal ghost imaging for different data processing methods. Particular attention is given to high-order thermal ghost imaging with background normalization and conventional ghost ... [Opt. Express 18, 5562-5573 (2010)]
Ki-Hong Yoon, Su Hwan Oh, Ki Soo Kim, O-Kyun Kwon, Dae Kon Oh, Young-Ouk Noh, Hyung-Jong LeeWe presented a hybridly-integrated tunable external cavity laser with 0.8 nm mode spacing 16 channels operating in the direct modulation of 2.5-Gbps for a low-cost source of a WDM-PON system. The tunable laser was fabricated by using a superluminescent diode (SLD) and a polymer Bragg reflector. The ... [Opt. Express 18, 5556-5561 (2010)]
Minzheng Duan, Qilong Min, Knut StamnesThe atmosphere is often divided into several homogeneous layers in simulations of radiative transfer in plane-parallel media. This artificial stratification introduces discontinuities in the vertical distribution of the inherent optical properties at boundaries between layers, which result in ... [Opt. Express 18, 5629-5638 (2010)]
Muhammad Anisuzzaman Talukder, Curtis R. MenyukWe consider the impact of saturable nonlinearity and group velocity dispersion on self-induced transparency (SIT) modelocking of quantum cascade lasers (QCLs). We find that self-induced transparency modelocking in QCLs can be obtained in the presence of saturable nonlinearity if the saturable loss ... [Opt. Express 18, 5639-5653 (2010)]
Byeong-Hyeon Ahn, Ju-Hyung Kang, Myung-Ki Kim, Jung-Hwan Song, Bumki Min, Ki-Soo Kim, Yong-Hee LeeWe report one-dimensional (1-D) parabolic-beam photonic crystal (PhC) lasers in which the width of the PhC slab waveguide is parabolically tapered. A few high-Q resonant modes are confirmed in the vicinity of the tapered region where Gaussian-shaped photonic well is formed. These resonant modes ... [Opt. Express 18, 5654-5660 (2010)]
Daniel D. Aguayo, Fernando Mendoza Santoyo, Manuel H. De la Torre-I, Manuel D. Salas-Araiza, Cristian Caloca-Mendez, David Asael Gutierrez HernandezAn out-of-plane digital holographic interferometry system is used to detect and measure insect’s wing micro deformations. The in-vivo phenomenon of the flapping is registered using a high power cw laser and a high speed camera. A series of digital holograms with the deformation encoded are ... [Opt. Express 18, 5661-5667 (2010)]
Yuya Shoji, Takeshi Ogasawara, Toshihiro Kamei, Youichi Sakakibara, Satoshi Suda, Kenji Kintaka, Hitoshi Kawashima, Makoto Okano, Toshifumi Hasama, Hiroshi Ishikawa, Masahiko MoriWe, for the first time, present the ultrafast optical nonlinear response of a hydrogenated amorphous silicon (a-Si:H) wire waveguide using femtosecond pulses. We show cross-phase and cross-absorption modulations measured using the heterodyne pump-probe method and estimate the optical Kerr ... [Opt. Express 18, 5668-5673 (2010)]
Xiaohua Jian, Chunmin Zhang, Lin Zhang, Baochang ZhaoBased on the basic imaging theory of the temporally and spatially mixed modulated polarization interference imaging spectrometer (TSMPIIS), a method of interferogram obtaining and processing under polychromatic light is presented. Especially, instead of traditional Fourier transform spectroscopy, ... [Opt. Express 18, 5674-5680 (2010)]
Konstantin V. Gilev, Elena Eremina, Maxim A. Yurkin, Valeri P. MaltsevThe discrete sources method (DSM) and the discrete dipole approximation (DDA) were compared for simulation of light scattering by a red blood cell (RBC) model. We considered RBCs with diameters up to 8 μm (size parameter up to 38), relative refractive indices 1.03 and 1.06, and two different ... [Opt. Express 18, 5681-5690 (2010)]
Shrestha Basu Mallick, Mukul Agrawal, Peter PeumansCrystalline silicon is an attractive photovoltaic material because of its natural abundance, accumulated materials and process knowledge, and its appropriate band gap. To reduce cost, thin films of crystalline silicon can be used. This reduces the amount of material needed and allows material with ... [Opt. Express 18, 5691-5706 (2010)]
Feng-Chun Leng, Wen-Yao Liang, Bin Liu, Tong-Biao Wang, He-Zhou WangWe find that the angle between elementary lattice vectors obviously affects the bandwidth and dispersion of slow light in photonic crystal line-defect waveguides. When the fluctuation of group index is strictly limited in a ±1% range, the oblique lattice structures with the angle between ... [Opt. Express 18, 5707-5712 (2010)]
Richard A. Kirian, Xiaoyu Wang, Uwe Weierstall, Kevin E. Schmidt, John C. H. Spence, Mark Hunter, Petra Fromme, Thomas White, Henry N. Chapman, James HoltonX-ray diffraction patterns may be obtained from individual submicron protein nanocrystals using a femtosecond pulse from a free-electron X-ray laser. Many “single-shot” patterns are read out every second from a stream of nanocrystals lying in random orientations. The short pulse ... [Opt. Express 18, 5713-5723 (2010)]
Lihua Zhao, Yudong Li, Jiwei Qi, Jingjun Xu, Qian SunOptical forces on a nanoparticle around an absorptive dielectric nano-fiber illuminated by two linear polarized counter-propagating beams were investigated. The results show the scattering force of the two beams causes the steady trapping along the fiber and the gradient force makes the trapping in ... [Opt. Express 18, 5724-5729 (2010)]
Chang-Hwan Im, Young-Jin Jung, Seungduk Lee, Dalkwon Koh, Do-Won Kim, Beop-Min KimThis study invesitigated the feasibility of measuring directional coupling between cortical areas with near-infrared spectroscopy (NIRS). Cerebral hemodynamic responses were recorded at the primary somatosensory cortex (S1), secondary somatosensory cortex (S2), and primary motor cortex (M1) regions ... [Opt. Express 18, 5730-5739 (2010)]
Etienne Gaufrès, Nicolas Izard, Xavier Le Roux, Saïd Kazaoui, Delphine Marris-Morini, Eric Cassan, Laurent VivienWe report studies of optical Fabry-Perot microcavities based on semiconducting single-wall carbon nanotubes with a quality factor of 160. We experimentally demonstrate a huge photoluminescence signal enhancement by a factor of 30 in comparison with the identical film and by a factor of 180 if ... [Opt. Express 18, 5740-5745 (2010)]
I. Cestier, V. Eckhouse, G. Eisenstein, S. Combrié, P. Colman, A. De RossiWe report a large nonlinear response in a 1.3mm long GaInP photonic crystal waveguide. The wide band gap of GaInP (1.9 eV) ensures that no two photon absorption takes place for photons at 1.55mm improving the nonlinear performance. The nonlinearity is enhanced by a resonance effect due to the ... [Opt. Express 18, 5746-5753 (2010)]
Hristo Iliev, Danail Chuchumishev, Ivan Buchvarov, Valentin PetrovExperimental results on passive mode-locking of a Nd:YVO_4 laser using intracavity frequency doubling in periodically poled KTP (PPKTP) crystal are reported. Both, negative cascaded χ^(2) lensing and frequency doubling nonlinear mirror (FDNLM) are exploited for the laser mode-locking. The ... [Opt. Express 18, 5754-5762 (2010)]
Wenhe Du, Liying Tan, Jing Ma, Yijun JiangNowadays it has been accepted that the Kolmogorov model is not the only possible turbulent one in the atmosphere, which has been confirmed by the increasing experimental evidences and some results of theoretical investigation. This has prompted the scientist community to study optical propagation ... [Opt. Express 18, 5763-5775 (2010)]
Roberto Caputo, Ivan Trebisacce, Luciano De Sio, Cesare UmetonMaterials showing birefringence and polarization selective absorption (dichroism) affect the polarization state of incoming light in a peculiar way, quite different from the one exhibited by phase retarders like waveplates. In this paper, we report on the characterization of a Polymer LIquid ... [Opt. Express 18, 5776-5784 (2010)]
Nicolás Sherwood-Droz, Alexander Gondarenko, Michal LipsonWe demonstrate a bulk silicon alternative to the conventional silicon-on-insulator photonics platform, using common CMOS process-based Si_3N_4 masking and oxidation techniques. We show waveguide losses as low as 2.92 dB/cm with a technique that can be implemented on the front-end of a typical CMOS ... [Opt. Express 18, 5785-5790 (2010)]
Yuzhu Liu, Bifeng Tang, Huan Shen, Song Zhang, Bing ZhangThe dynamics of excited states in o-xylene molecules has been studied by femtosecond time-resolved photoelectron imaging coupled with time-resolved mass spectroscopy. The ultrafast internal conversion from the S_2 state to the vibrationally hot S_1 state on timescale of 60 fs is observed on real ... [Opt. Express 18, 5791-5801 (2010)]
L. A. Ambrosio, H. E. Hernández-FigueroaThe unexpected fact that a spherical dielectric particle with refractive index higher than the surrounding medium will not always be attracted towards high intensity regions of the trapping beam is fully demonstrated here using a simple ray optics approach. This unusual situation may happen due to ... [Opt. Express 18, 5802-5808 (2010)]
T. Grosjean, I. A. Ibrahim, M. A. Suarez, G. W. Burr, M. Mivelle, D. CharrautWe propose a concept of near-field imaging for the complete experimental description of the structure of light in three dimensions around nanodevices. It is based on a near-field microscope able to simultaneously map the distributions of two orthogonal electric-field components at the sample ... [Opt. Express 18, 5809-5824 (2010)]
M. V. Balabas, K. Jensen, W. Wasilewski, H. Krauter, L. S. Madsen, J. H. Müller, T. Fernholz, E. S. PolzikWe present an experimental investigation of alkali atom vapor cells coated with a high quality anti-relaxation coating material based on alkenes. The prepared cells with single compound alkene based coating showed the longest spin relaxation times which have been measured up to now with room ... [Opt. Express 18, 5825-5830 (2010)]
Juju Hu, Haijiang Hu, Yinghua JiPeriodic nonlinearity that ranges from tens of nanometers to a few nanometers in heterodyne interferometer limits its use in high accuracy measurement. A novel method is studied to detect the nonlinearity errors based on the electrical subdivision and the analysis method of statistical signal in ... [Opt. Express 18, 5831-5839 (2010)]
Ankit Mathur, David A. Atchison, W. Neil CharmanAbstract: On-axis monochromatic higher-order aberrations increase with age. Few studies have been made of peripheral refraction along the horizontal meridian of older eyes, and none of their off-axis higher-order aberrations. We measured wave aberrations over the central 42°x32° visual ... [Opt. Express 18, 5840-5853 (2010)]
Zu-Bin Li, Wen-Yuan Zhou, Xiang-Tian Kong, Jian-Guo TianBy setting a metal rod or tooth-type structures in a single subwavelength hole, its near-field can be strongly enhanced. The near-field enhancement has strong polarization dependence when the structure in hole is twofold symmetric. Only the polarization along the longitudinal side of the metal rod ... [Opt. Express 18, 5854-5860 (2010)]
Yijie Huo, Christian C. Fesenmaier, Peter B. CatrysseCMOS image sensors with smaller pixels are expected to enable digital imaging systems with better resolution. When pixel size scales below 2 μm, however, diffraction affects the optical performance of the pixel and its microlens, in particular. We present a first-principles electromagnetic ... [Opt. Express 18, 5861-5872 (2010)]
Daohong Song, Cibo Lou, Kody J. H. Law, Liqin Tang, Zhuoyi Ye, P.G. Kevrekidis, Jingjun Xu, Zhigang ChenWe demonstrate self-trapping of singly-charged vortices at the surface of an optically induced two-dimensional photonic lattice. Under appropriate conditions of self-focusing nonlinearity, a singly-charged vortex beam can self-trap into a stable semi-infinite gap surface vortex soliton through a ... [Opt. Express 18, 5873-5878 (2010)]
Xiaofeng Duan, Yongqing Huang, Xiaomin Ren, Hui Huang, Sanxian Xie, Qi Wang, Shiwei CaiAn integrated reconfigurable four-channel wavelength-division-multiplexed drop module for use in the long-wavelength was demonstrated using a tunable wavelength-selective photodetector array. The array consists of an InP-based p-i-n absorption structure and a GaAs-based multistep Fabry-Pérot ... [Opt. Express 18, 5879-5889 (2010)]
M. Stroisch, T. Woggon, C. Teiwes-Morin, S. Klinkhammer, K. Forberich, A. Gombert, M. Gerken, U. LemmerWe modified the optical properties of organic semiconductor distributed feedback lasers by introducing a high refractive index layer consisting of tantalum pentoxide between the substrate and the active material layer. A thin film of tris-(8-hydroxyquinoline) aluminium doped with the laser dye ... [Opt. Express 18, 5890-5895 (2010)]
Mridu P. Kalita, Shaif-ul Alam, Christophe Codemard, Seongwoo Yoo, Alexander J. Boyland, Morten Ibsen, Jayanta K. SahuAn all-fiber, narrow-linewidth, high power Yb-doped silica fiber laser at 1179 nm has been demonstrated. More than 12 W output power has been obtained, corresponding to a slope efficiency of 43% with respect to launched pump power, by core-pumping at 1090 nm. In order to increase the pump ... [Opt. Express 18, 5920-5925 (2010)]
Ran Hao, Eric Cassan, Hamza Kurt, Xavier Le Roux, Delphine Marris-Morini, Laurent Vivien, Huaming Wu, Zhiping Zhou, Xinliang ZhangWe demonstrate a novel type of slow light photonic crystal waveguide which can produce unusual “U” type group index - frequency curves with constant group index n_g over large bandwidth. By shifting the boundaries of this waveguide, flexible control of n_g (10 < 210) with ... [Opt. Express 18, 5942-5950 (2010)]
Ning-Ning Dong, Feng Chen, Daniel JaqueWe report on the micron-luminescent properties of carbon ion implanted optical channel waveguides in the Nd:MgO:LiNbO_3 laser crystals. The confocal fluorescence images of the waveguide’s cross section are presented based on the analysis of the spatial variation of the Nd^3+ fluorescence ... [Opt. Express 18, 5951-5956 (2010)]
Yosuke Mizuno, Zuyuan He, Kazuo HotateWe have demonstrated a double-modulation scheme to enlarge the measurement range of Brillouin optical correlation-domain reflectometry for fiber-optic distributed strain sensing. In this scheme, the frequency of the laser output is simultaneously modulated with two different frequencies. In the ... [Opt. Express 18, 5926-5933 (2010)]
Yuen Yung Hui, Bailin Zhang, Yuan-Chang Chang, Cheng-Chun Chang, Huan-Cheng Chang, Jui-Hung Hsu, Karen Chang, Fu-Hsiung ChangDynamics of fluorescent diamond nanoparticles in HeLa cells has been studied with two-photon fluorescence correlation spectroscopy (FCS). Fluorescent nanodiamond (FND) is an excellent fluorescent probe for bioimaging application, but they are often trapped in endosomes after cellular uptake. The ... [Opt. Express 18, 5896-5905 (2010)]
Jungmi Oh, Cristian Antonelli, Moshe Tur, Misha BrodskyWe derive an analytical expression for the count probability of a single photon detector for a wide range of input optical power that includes afterpulsing effects. We confirm the validity of the expression by fitting it to the data obtained from a saturated commercial Single Photon Detector by ... [Opt. Express 18, 5906-5911 (2010)]
K. Gauthron, J-S. Lauret, L. Doyennette, G. Lanty, A. Al Choueiry, S. J. Zhang, A. Brehier, L. Largeau, O. Mauguin, J. Bloch, E. DeleporteWe report on optical spectroscopy (photoluminescence and photoluminescence excitation) on two-dimensional self-organized layers of (C_6H_5C_2H_4-NH_3)_2-PbI_4 perovskite. Temperature and excitation power dependance of the optical spectra gives a new insight into the excitonic and the phononic ... [Opt. Express 18, 5912-5919 (2010)]
Marco Peccianti, Ian B. Burgess, Gaetano Assanto, Roberto MorandottiWe introduce the generation of dense trains of light-bullets in nonlocal nonlinear dielectrics. We exploit stable spatio-temporal self-trapped optical packets stemming from the interplay between local electronic and nonlocal reorientational nonlinearities, considering a seeded temporal modulation ... [Opt. Express 18, 5934-5941 (2010)]
Wei E. I. Sha, Wallace C. H. Choy, Weng Cho ChewA comprehensive study of the plasmonic thin-film solar cell with the periodic strip structure is presented in this paper. The finite-difference frequency-domain method is employed to discretize the inhomogeneous wave function for modeling the solar cell. In particular, the hybrid absorbing boundary ... [Opt. Express 18, 5993-6007 (2010)]
Li Yan, Lijun Ma, Xiao TangWe propose a new method to narrow the line width of entangled photons generated from spontaneous parametric downconversion (SPDC). The single structure device incorporates an internal Bragg grating onto a nonlinear optical waveguide. We study theoretically the spectral characteristics of SPDC under ... [Opt. Express 18, 5957-5963 (2010)]
Gary Shambat, Yiyang Gong, Jesse Lu, Selçuk Yerci, Rui Li, Luca Dal Negro, Jelena VučkovićOptical fiber tapers are used to collect photoluminescence emission at ~1.5 µm from photonic crystal cavities fabricated in erbium doped silicon nitride on silicon. In the experiment, photoluminescence collection via one arm of the fiber taper is enhanced 2.5 times relative to free space ... [Opt. Express 18, 5964-5973 (2010)]
R. Gebs, G. Klatt, C. Janke, T. Dekorsy, A. BartelsWe report an ultrafast time-domain spectroscopy system based on high-speed asynchronous optical sampling operating without mechanical scanner. The system uses two 1 GHz femtosecond oscillators that are offset-stabilized using high-bandwidth feedback electronics operating at the tenth repetition ... [Opt. Express 18, 5974-5983 (2010)]
Andrew J. Lee, Helen M. Pask, James A. Piper, Huaijin Zhang, Jiyang WangWe report the generation of multi-watt continuous-wave (CW) yellow laser emission from an intracavity diode-pumped Nd:GdVO_4 /BaWO_4 Raman laser utilising a high-Q resonator (for fundamental and first-Stokes wavelengths) and intracavity frequency-doubling in LBO. CW output power of 2.9 W is ... [Opt. Express 18, 5984-5992 (2010)]
Gabriella Cipparrone, Ibis Ricardez-Vargas, Pasquale Pagliusi, Clementina ProvenzanoWe report a study of the capabilities of an optical tweezer based on polarization gradient. We use a light polarization pattern that is able to simultaneously exert forces and torques in opposite directions depending on the particle’s position. It allows to perform oscillatory displacements ... [Opt. Express 18, 6008-6013 (2010)]
Kuo-Yung Hung, Chao-Chih Fan, Fan-Gang Tseng, Yi-Ko ChenThe purpose of this paper is to use thermal energy and electrostatic force as an alternative to high-cost precision cutting or traditional injection molding in the fabrication of COC (cyclo-olefin copolymer) plastic aspheric bi-convex lenses with high Blu-Ray transmittance (92% at 405 nm). A glass ... [Opt. Express 18, 6014-6023 (2010)]
D. Coquillat, S. Nadar, F. Teppe, N. Dyakonova, S. Boubanga-Tombet, W. Knap, T. Nishimura, T. Otsuji, Y. M. Meziani, G. M. Tsymbalov, V. V. PopovRoom temperature photovoltaic non-resonant detection by large area double-grating-gate InGaP/InGaAs/GaAs heterostructures was investigated in sub-THz range (0.24 THz). Semi-quantitative estimation of the characteristic detection length combined with self-consistent calculations of the electric ... [Opt. Express 18, 6024-6032 (2010)]
A. J. Pearlman, A. Ling, E. A. Goldschmidt, C. F. Wildfeuer, J. Fan, A. MigdallWe experimentally map the transverse profile of diffractionlimited beams using photon-number-resolving detectors.We observe strong compression of diffracted beam profiles for high detected photon number. This effect leads to higher contrast than a conventional irradiance profile between two Airy ... [Opt. Express 18, 6033-6039 (2010)]
Sanshui Xiao, Liang Peng, Niels Asger MortensenTransmission through sub-wavelength apertures in perfect metals is expected to be strongly suppressed. However, by structural engineering of the apertures, we numerically demonstrate that the transmission of transverse electric waves through periodic arrays of subwavelength apertures in a thin ... [Opt. Express 18, 6040-6047 (2010)]
Shuang Zhang, Yong-Shik Park, Yongmin Liu, Thomas Zentgraf, Xiang ZhangLight-matter interaction can be greatly enhanced in nano-scale plasmonic cavities with tightly confined optical mode, where the mode volume determines the interaction strength. The experimental determination of the mode volume of plasmonic elements is therefore of fundamental importance. Mapping ... [Opt. Express 18, 6048-6055 (2010)]
Ai-Ping Luo, Zhi-Chao Luo, Wen-Cheng Xu, Hu CuiA wavelength switchable all-fiber comb filter with flat-top spectral response based on a double-loop Mach-Zehnder (M-Z) interferometer is proposed and demonstrated. The proposed flat-top filter consists of a rotatable polarizer and a double-loop M-Z interferometer composed of two fiber couplers ... [Opt. Express 18, 6056-6063 (2010)]
Guo-Wei Lu, Satoshi Shinada, Hideaki Furukawa, Naoya Wada, Tetsuya Miyazaki, Hiromasa ItoWe experimentally demonstrated ultra-fast phase-transparent wavelength conversion using cascaded sum- and difference-frequency generation (cSFG-DFG) in linear-chirped periodically poled lithium niobate (PPLN). Error-free wavelength conversion of a 160-Gb/s return-to-zero differential phase-shift ... [Opt. Express 18, 6064-6070 (2010)]
Motohiko Ito, Yoshimasa Kataoka, Tatsuya Okamoto, Mikio Yamashita, Taro SekikawaExtreme ultraviolet (XUV) single-order high harmonic pulses with 10^6 photons/pulse were separated from multiple harmonic orders by a time-compensated toroidal-grating monochromator consisting of a pair of toroidal gratings. The first grating separates the harmonic order and the second one ... [Opt. Express 18, 6071-6078 (2010)]
Z. Wang, M. P. Fok, L. Xu, J. Chang, P. R. PrucnalTemporal phase modulation of spread stealth signals is proposed and demonstrated to improve optical steganography transmission privacy. After phase modulation, the temporally spread stealth signal has a more complex spectral-phase-temporal relationship, such that the original temporal profile ... [Opt. Express 18, 6079-6088 (2010)]
Zheng Chang, Xiaoming Zhou, Jin Hu, Gengkai HuRecently, there are emerging demands for isotropic material parameters, arising from the broadband requirement of the functional devices. Since inverse Laplace’s equation with sliding boundary condition will determine a quasi-conformal mapping, and a quasi-conformal mapping will minimize the ... [Opt. Express 18, 6089-6096 (2010)]
Nico Vieweg, Christian Jansen, Mohammad Khaled Shakfa, Maik Scheller, Norman Krumbholz, Rafal Wilk, Martin Mikulics, Martin KochWe report on a first experimental study of the molecular properties of nematic liquid crystals in the terahertz range. In the beginning, we extract the frequency and temperature dependent refractive index and absorption coefficient of the cyanobiphenyls 5CB, 6CB and 7CB from terahertz time domain ... [Opt. Express 18, 6097-6107 (2010)]
Chun-Ting LinThe 400-channel 25-GHz-spacing SOI-based planar waveguide demultiplexer employing a concave grating across C- and L-bands is proposed in this paper. For the high polarization dependence, the waveguides are designed for supporting the TE mode only. To reduce the spherical aberration of the concave ... [Opt. Express 18, 6108-6115 (2010)]
Chao-Yu Chung, Yen-Yin Lin, Kuo-Yu Wu, Wan-Yu Tai, Shi-Wei Chu, Yao-Chang Lee, Yeukuang Hwu, Yin-Yu LeeWe have demonstrated coherent anti-Stokes Raman scattering (CARS) microscopy with a single-pass picosecond supercontinuum-seeded optical parametric amplifier (SCOPA). The SCOPA was pumped by a frequency-doubled picosecond passively mode-locked Nd:YVO_4 laser, and was seeded by a supercontinuum ... [Opt. Express 18, 6116-6122 (2010)]
Hon-Tung Wong, Helen Lai Wa Chan, Jianhua HaoNearly pure near-infrared to near-infrared (NIR-to-NIR) upconversion in GdF_3 host with 23% Yb^3+ and 1% Tm^3+ under 980 nm excitation is firstly reported. The ratio of the intensity of the emission at 807 nm to that at 478 nm can reach to 105, and the intensity of the emission at 807 nm is ... [Opt. Express 18, 6123-6130 (2010)]
Zhifeng Lin, Xin Wang, Frank Kallmeyer, Hans Joachim Eichler, Chunqing GaoSingle frequency operation of a diode-pumped tunable injection-seeded Nd:GSAG Q-switched laser around 942nm was demonstrated. With a three-mirror ring cavity, the single frequency laser pulse with output energy of 13.2mJ was obtained at a repetition rate of 10Hz. The linewidth of the single ... [Opt. Express 18, 6131-6136 (2010)]
Ching-Cherng Sun, Wei-Ting Chien, Ivan Moreno, Chih-To Hsieh, Mo-Cha Lin, Shu-Li Hsiao, Xuan-Hao LeeA lighting cavity is a reflecting box with light sources inside. Its exit side is covered with a diffuser plate to mix and distribute light, which addresses a key issue of luminaires, display backlights, and other illumination systems. We derive a simple but precise formula for the optical ... [Opt. Express 18, 6137-6148 (2010)]
Yu Wang, Heng Shen, Xiaoli Jin, Xiaolong Su, Changde Xie, Kunchi PengWe experimentally demonstrated that the quantum correlations of amplitude and phase quadratures between signal and idler beams produced from a non-degenerate optical parametric amplifier (NOPA) can be significantly improved by using a mode cleaner in the pump field and reducing the phase ... [Opt. Express 18, 6149-6155 (2010)]
Weiqi Xue, Salvador Sales, José Capmany, Jesper MørkIn this work we demonstrate for the first time, to the best of our knowledge, a continuously tunable 360° microwave phase shifter spanning a microwave bandwidth of several tens of GHz (up to 40 GHz). The proposed device exploits the phenomenon of coherent population oscillations, enhanced by ... [Opt. Express 18, 6156-6163 (2010)]
N. Krebs, R. A. Probst, E. RiedleDirect pulse shaping in the UV was used to compress and structure pulses throughout the range of 250 – 400 nm. Broadband pulses generated by SHG of a NOPA were used as input to an acousto-optic programmable dispersive filter. As this shaper creates lateral dispersion, aspects of Gaussian and ... [Opt. Express 18, 6164-6171 (2010)]
Minhao Pu, Liu Liu, Weiqi Xue, Yunhong Ding, Haiyan Ou, Kresten Yvind, Jørn M. HvamWe propose and demonstrate tunable microwave phase shifters based on electrically tunable silicon-on-insulator microring resonators. The phase-shifting range and the RF-power variation are analyzed. A maximum phase-shifting range of 0~600° is achieved by utilizing a dual-microring resonator. ... [Opt. Express 18, 6172-6182 (2010)]
Guichuan Xing, Jiang Jiang, Jackie Y. Ying, Wei JiWe report the observation of optical limiting in Fe_3O_4-Ag nanocomposites in solution. With these nanocomposites, we demonstrate that broad temporal optical limiting can be accomplished with low limiting threshold. Due to the presence of Ag nanoparticles, nonlinear scattering gives rise to ... [Opt. Express 18, 6183-6190 (2010)]
Asanka Pannipitiya, Ivan D. Rukhlenko, Malin Premaratne, Haroldo T. Hattori, Govind P. AgrawalWe present an improved analytical model describing transmittance of a metal-dielectric-metal (MDM) waveguide coupled to an arbitrary number of stubs. The model is built on the well-known analogy between MDM waveguides and microwave transmission lines. This analogy allows one to establish equivalent ... [Opt. Express 18, 6191-6204 (2010)]
John M. Harlander, James E. Lawler, Jason Corliss, Fred L. Roesler, Walter M. HarrisOperation of an all-reflection, broadband, spatial heterodyne spectrometer (SHS) is reported. This Mark 2 SHS is constructed using a custom diffraction grating and other standard optical components. The custom grating is coarse (18 grooves/mm), with a symmetric blaze that allows its simultaneous ... [Opt. Express 18, 6205-6210 (2010)]
Optics Letters
Show articles…George Huyang, John Canning, Mattias L. Åslund, Danial Stocks, Tony Khoury, Maxwell J. CrossleyAn optical fiber acid-sensor based on protonation of a porphyrin solution within a single-hole structured optical fiber is proposed and demonstrated. The liquid-core fiber acts as a microcell reactor, and changes in the spectral signature with acidification are detected. Challenges and limitations ... [Opt. Lett. 35, 817-819 (2010)]
Chien-Chung Tsai, Ting-Hao Chen, Yen-Sheng Lin, Yu-Ta Wang, Wei Chang, Kuang-Yu Hsu, Yung-Hsin Chang, Po-Kai Hsu, Dong-Yo Jheng, Kuang-Yao Huang, Edmund Sun, Sheng-Lung HuangA Ce^3+:YAG double-clad crystal fiber (DCF) visible emission was used as the light source for optical coherence tomography (OCT). The visible emission was produced from a 10 μm core DCF pumped by a diode laser. The broadband emission and short central wavelength of this light source enabled ... [Opt. Lett. 35, 811-813 (2010)]
Russell Kliese, Yah Leng Lim, Thierry Bosch, Aleksandar D. RakićThe self-mixing (SM) laser sensing technique allows for a simple, self-aligned, and robust system for measuring velocity. Low-cost blue emitting GaN laser diodes have recently become available owing to the high volume requirements for Blu-ray Disc devices such as high-definition video players and ... [Opt. Lett. 35, 814-816 (2010)]
Yongwoo Park, José AzañaWe show that a fiber-optics architecture conventionally used for microwave photonic filtering can implement a time-spectrum convolution (TSC) process of general interest for a wide range of fundamental optical signal processing and analysis operations. This process is practically implemented by ... [Opt. Lett. 35, 796-798 (2010)]
Ibrahim Ozdur, Mehmetcan Akbulut, Nazanin Hoghooghi, Dimitrios Mandridis, Mohammad U. Piracha, Peter J. DelfyettA 10.287 GHz optoelectronic oscillator is experimentally demonstrated that uses a 1000 finesse Fabry-Perot etalon as the mode selector instead of an rf filter. The results are compared with a standard optoelectronic loop with an rf filter. The substitution of the rf filter with the optical filter ... [Opt. Lett. 35, 799-801 (2010)]
Milja Medic, Joseph B. Altepeter, Matthew A. Hall, Monika Patel, Prem KumarWe have constructed and experimentally characterized what we believe to be the first fiber-based source of degenerate polarization-entangled photon pairs in the telecommunication band. Our source design utilizes bichromatic pump pulses and an optical-fiber Sagnac loop aligned to deterministically ... [Opt. Lett. 35, 802-804 (2010)]
Isao Tomita, Takeshi Umeki, Osamu Tadanaga, Hongbin Song, Masaki AsobeWe developed an apodized multiple quasi-phase-matched (QPM) LiNbO_3 device to reduce the cross talk that occurs during waveband conversion. Since we found that the cross talk arises from ripples between multiple QPM peaks in the phase-matching curve, we reduced the amplitude of the ripples by ... [Opt. Lett. 35, 805-807 (2010)]
Xin Mi Yang, Xiao Yang Zhou, Qiang Cheng, Hui Feng Ma, Tie Jun CuiWe have demonstrated that a thin planar coating with randomly distributed index gradients can create diffuse reflections in front of a planar conducting sheet. This scheme is verified by two-dimensional near-field scanning measurement, in which the randomly gradient index coating is implemented by ... [Opt. Lett. 35, 808-810 (2010)]
P. Groß, I. D. Lindsay, C. J. Lee, M. Nittmann, T. Bauer, J. Bartschke, U. Warring, A. Fischer, A. Kellerbauer, K.-J. BollerWe report the realization of a singly resonant optical parametric oscillator (SRO) that is designed to provide narrow-bandwidth, continuously tunable radiation at a wavelength of 1163 nm for optical cooling of osmium ions. The SRO is based on periodically poled, magnesium-oxide-doped lithium ... [Opt. Lett. 35, 820-822 (2010)]
Jae-Jun Kim, Sunki Chae, Ki-Hun JeongThis work presents a simple and effective method for a wide-angle light-emitting diode module by using a single lens corrugated with micropattern arrays. Impinged onto the micropattern arrays of a curved surface, light undergoes an enhancement of the illumination angle due to omnidirectional ... [Opt. Lett. 35, 823-825 (2010)]
Y. Q. Xu, S. G. MurdochWe present an investigation of the statistics of the gain fluctuations of a fiber optical parametric amplifier pumped with a temporally incoherent pump. We derive a simple expression for the probability distribution of the gain of the amplified optical signal. The gain statistics are shown to be a ... [Opt. Lett. 35, 826-828 (2010)]
I. Liontos, S. Cavalieri, C. Corsi, R. Eramo, S. Kaziannis, A. Pirri, E. Sali, M. BelliniWe report the experimental measurement of Ramsey interference fringes in the single-photon excitation to a high-lying bound state of atomic argon by pairs of phase-locked, time-delayed, extreme UV high-order-harmonic pulses at 87 nm. High-visibility Ramsey fringes are observed for delays larger ... [Opt. Lett. 35, 832-834 (2010)]
Krassimir Panajotov, Maciej DemsBy calculating the band diagrams for the distributed Bragg mirrors of vertical-cavity surface-emitting lasers (VCSELs) with triangular two-dimensional lattice of etched holes we show that true photonic bandgap (PBG) confinement is possible for TE-like polarized light. We confirm this true PBG ... [Opt. Lett. 35, 829-831 (2010)]
Shengchun Liu, Zuowei Yin, Liang Zhang, Liang Gao, Xiangfei Chen, Jianchun ChengA multilongitudinal mode fiber laser sensor formed by two fiber Bragg gratings and a piece of erbium-doped fiber is first proposed and validated experimentally. When the strain is applied on the sensor, the laser cavity is stretched, which leads to a change of round-trip frequency. Thus the strain ... [Opt. Lett. 35, 835-837 (2010)]
Ashwin A. Wagadarikar, Daniel L. Marks, Kerkil Choi, Ryoichi Horisaki, David J. BradyPrevious studies have shown that the isoplanatic distortion due to turbulence and the image of a remote object may be jointly estimated from the 4D mutual intensity across an aperture. This Letter shows that decompressive inference on a 2D slice of the 4D mutual intensity, as measured by a ... [Opt. Lett. 35, 838-840 (2010)]
Emre Coşkun, Kıvanç Sel, Serhat ÖzderThe generalized S-transform was improved as a method to determine the refractive index of a dielectric film continuously by using the transmittance spectrum, and the applicability of the method was demonstrated on mica. The result determined from the generalized S-transform method was compared with ... [Opt. Lett. 35, 841-843 (2010)]
Lieven Verslegers, Peter B. Catrysse, Zongfu Yu, Wonseok Shin, Zhichao Ruan, Shanhui FanWe demonstrate numerically, using a three-dimensional finite-difference frequency-domain method, the ability to design a phase front using an array of metallic pillars. We show that in such structures, the local phase delay upon transmission can be tuned by local geometry. We apply this knowledge ... [Opt. Lett. 35, 844-846 (2010)]
Tao Wang, Daomu ZhaoThe spectral coherence of a light wave on scattering is closely related with the properties of the scattering medium. Within the accuracy of the first-order Born approximation, we present the condition for the invariance of the spectral degree of the coherence of a spatially coherent scalar plane ... [Opt. Lett. 35, 847-849 (2010)]
Recent articles in Physical Review Letters
Show articles…Author(s): Samuel Johnson, Joaquín J. Torres, J. Marro, and Miguel A. MuñozWhy are most empirical networks, with the prominent exception of social ones, generically degree-degree anticorrelated? To answer this long-standing question, we define the ensemble of correlated networks and obtain the associated Shannon entropy. Maximum entropy can correspond to either assortative...[Phys. Rev. Lett. 104, 108702] Published Thu Mar 11, 2010
Author(s): Kai Sun, Michael J. Lawler, and Eun-Ah KimWe study the interplay between charge and spin ordering in electronic liquid crystalline states with a particular emphasis on fluctuating spin stripe phenomena observed in recent neutron scattering experiments. Based on a phenomenological model, we propose that charge nematic ordering is indeed behi...[Phys. Rev. Lett. 104, 106405] Published Thu Mar 11, 2010
Author(s): T. Hofmann, M. Tasinkevych, A. Checco, E. Dobisz, S. Dietrich, and B. M. OckoThe wetting by perfluoromethylcyclohexane of a well-defined silicon grating with a channel width of 16 nm has been studied using transmission small angle x-ray scattering. Prefilling, capillary filling, and postfilling wetting regimes have been identified. A detailed comparison of the data with the...[Phys. Rev. Lett. 104, 106102] Published Thu Mar 11, 2010
Author(s): A. Taranovskyy, T. Tansel, and O. M. MagnussenThe interactions between adsorbates at a solid-liquid interface were studied by video-rate STM for the case of sulfur on Cu(100) electrode surfaces in HCl solution. Quantitative data were obtained by analyzing the S_{ad} dimer dynamics within the surrounding c(2×2)-Cl adlattice as well as the adsor...[Phys. Rev. Lett. 104, 106101] Published Thu Mar 11, 2010
Author(s): Qiao-shi Zeng, Yang Ding, Wendy L. Mao, Wenge Yang, Stas. V. Sinogeikin, Jinfu Shu, Ho-kwang Mao, and J. Z. JiangUsing high-pressure synchrotron x-ray absorption spectroscopy, we observed the Ce 4f electron in Ce_{75} Al_{25} metallic glass transform from its ambient localized state to an itinerant state above 5 GPa. A parallel x-ray diffraction study revealed a volume collapse of about 8.6%, coinciding with ...[Phys. Rev. Lett. 104, 105702] Published Thu Mar 11, 2010
Author(s): M. Shats, H. Punzmann, and H. XiaWe report the first observation of extreme wave events (rogue waves) in parametrically driven capillary waves. Rogue waves are observed above a certain threshold in forcing. Above this threshold, frequency spectra broaden and develop exponential tails. For the first time we present evidence of stron...[Phys. Rev. Lett. 104, 104503] Published Thu Mar 11, 2010
Author(s): Yanne K. Chembo, Dmitry V. Strekalov, and Nan YuOptical frequency comb generation in whispering gallery mode resonators has been demonstrated in several experiments. The spectra of the combs exhibit a wide variety of complex profiles that are not fully understood. We report a detailed study on frequency comb generation in whispering gallery mode ...[Phys. Rev. Lett. 104, 103902] Published Thu Mar 11, 2010
Author(s): Frank Baumgartner and Hanspeter HelmWe show experimentally that an external electric field can be used to control the amplitudes of nonadiabatic paths taken by a dissociating molecule. In the example presented here, this control is achieved by Stark-field mixing in H_{3} Rydberg states with different decay paths. The final state conti...[Phys. Rev. Lett. 104, 103002] Published Thu Mar 11, 2010
Author(s): T. Aaltonen et al. (CDF Collaboration)We report a measurement of the lifetime of the Λ_{b}^{0} baryon in decays to the Λ_{c}^{+} π^{-} final state in a sample corresponding to 1.1 fb^{-1} collected in pp [over ¯] collisions at sqrt[s] =1.96 TeV by the CDF II detector at the Tevatron collider. Using a sample of about 3000 f...[Phys. Rev. Lett. 104, 102002] Published Thu Mar 11, 2010
Author(s): T. Aaltonen et al. (CDF Collaboration)We report a measurement of the lifetime of the Λ_{b}^{0} baryon in decays to the Λ_{c}^{+} π^{-} final state in a sample corresponding to 1.1 fb^{-1} collected in pp [over ¯] collisions at sqrt[s] =1.96 TeV by the CDF II detector at the Tevatron collider. Using a sample of about 3000 f...[Phys. Rev. Lett. 104, 102002] Published Thu Mar 11, 2010
Proceedings of the National Academy of Sciences RSS feed -- current issue
Show articles…Random graphs are useful models of social and technological networks. To date, most of the research in this area has...
It is widely believed, at least in scientific circles, that living systems, including mankind, obey the natural physical laws. However,...
Electrical actuators made from films of dielectric elastomers coated on both sides with stretchable electrodes may potentially be applied in...
Recommender systems use data on past user preferences to predict possible future likes and interests. A key challenge is that...
Abundant plant biomass has the potential to become a sustainable source of fuels and chemicals. Realizing this potential requires the...
We have investigated the mechanism of action of Aquifex aeolicus IspH [E-4-hydroxy-3-methyl-but-2-enyl diphosphate (HMBPP) reductase], together with its inhibition, using...
The electrode potential constitutes a dynamical variable whenever an electrode is resistively coupled to the electric circuit. We show that...
Biogeographical, physiological, and paleoecological evidence suggests that the coast redwood [Sequoia sempervirens (D. Don) Endl.] is closely associated with the...
Thermal conductivity of the Earth’s lower mantle greatly impacts the mantle convection style and affects the heat conduction from the...
Evaluating the specificity spectra of DNA binding molecules is a nontrivial challenge that hinders the ability to decipher gene regulatory...
Dengue and dengue hemorrhagic fever are increasing public health problems with an estimated 50–100 million new infections each year. Aedes aegypti...
Prior evidence supporting the direct observation of phosphorane intermediates in enzymatic phosphoryl transfer reactions was based on the interpretation of...
The proteomes of blood plasma and serum represent a potential gold mine of biological and diagnostic information, but challenges such...
Ribosomal protein S5 is critical for small ribosomal subunit (SSU) assembly and is indispensable for SSU function. Previously, we identified...
Protein tyrosine phosphatases are often exploited and subverted by pathogenic bacteria to cause human diseases. The tyrosine phosphatase mPTPB from...
In unstressed cells, the tumor suppressor p53 is maintained at low levels by ubiquitin-mediated proteolysis mainly through Mdm2. In response...
An indispensable step in protein biosynthesis is the 2'(3') aminoacylation of tRNA by aminoacyl-tRNA synthetases. Here we show that a...
Most bacterial chromosomes contain homologs of plasmid partitioning (par) loci. These loci encode ATPases called ParA that are thought to...
The vitrification of a liquid occurs when ice crystal formation is prevented in the cryogenic environment through ultrarapid cooling. In...
Mesenchyme is generally believed to play critical roles in "secondary induction" during organogenesis. Because of the complexity of tissue interactions...
A fundamental question in nutritional biology is how distributed systems maintain an optimal supply of multiple nutrients essential for life...
The herbicide atrazine is one of the most commonly applied pesticides in the world. As a result, atrazine is the...
Plant litter decomposition is a critical step in the formation of soil organic matter, the mineralization of organic nutrients, and...
Although Pentapetalae (comprising all core eudicots except Gunnerales) include 70% of all angiosperms, the origin of and relationships among the...
Modeling the interplay between mutation and selection at the molecular level is key to evolutionary studies. To this end, codon-based...
The evolutionary theory of aging predicts that species will experience delayed senescence and increased longevity when rates of extrinsic mortality...
Dietary fat accumulates in lipid droplets or endolysosomal compartments that undergo selective expansion under normal or pathophysiological conditions. We find...
Histones play a crucial role in the organization of DNA in the nucleus, but their presence can prevent interactions with...
Peptide vaccines enhance the response of T cells toward tumor antigens and represent a strategy to augment antigen-independent immunotherapies of...
There is increasing appreciation of the important role of B cells in many autoimmune diseases and consequently, increasing interest in...
IFN-regulatory factor 5 (IRF-5), a member of the IRF family, is a transcription factor that has a key role in...
Biodegradable scaffolds seeded with bone marrow mononuclear cells (BMCs) are the earliest tissue-engineered vascular grafts (TEVGs) to be used clinically....
The HIF family of hypoxia-inducible transcription factors are key mediators of the physiologic response to hypoxia, whose dysregulation promotes tumorigenesis....
Bacterial cells are highly organized with many protein complexes and DNA loci dynamically positioned to distinct subcellular sites over the...
The spread of avian H5N1 influenza viruses around the globe has become a worldwide public health concern. To evaluate the...
Relatively little is understood about the dynamics of global host–pathogen transcriptome changes that occur during bacterial infection of mucosal surfaces....
Bacterial pathogens deliver effector proteins with diverse biochemical activities into host cells, thereby modulating various host functions. Legionella pneumophila hijacks...
General intelligence (g) captures the performance variance shared across cognitive tasks and correlates with real-world success. Yet it remains debated...
Despite considerable evidence for a critical role of neuroligin-1 in the specification of excitatory synapses, the cellular mechanisms and physiological...
To analyze the in vivo structure of antigen-specific immunological synapses during an effective immune response, we established brain tumors expressing...
It is widely believed that sensory and motor processing in the brain is based on simple computational primitives rooted in...
Despite several attempts to define retinotopic maps in the macaque lateral intraparietal area (LIP) using histological, electrophysiological, and neuroimaging methods,...
Although it is being successfully implemented for exploration of the genome, discovery science has eluded the functional neuroimaging community. The...
Photoreceptor cells are remarkable in their ability to adjust their sensitivity to light over a wide range of intensities. Rapid...
To identify molecules that could enhance sweetness perception, we undertook the screening of a compound library using a cell-based assay...
Positive allosteric modulators of the human sweet taste receptor have been developed as a new way of reducing dietary sugar...
In adults, specific neural systems with right-hemispheric weighting are necessary to process pitch, melody, and harmony as well as structure...
Mammalian target of rapamycin (mTOR) constitutes a nodal point of a signaling network that regulates cell growth and proliferation in...
Islet β-cells express both insulin receptors and insulin-signaling proteins. Recent evidence from rodents in vivo and from islets isolated from...
Plants use light as a source of energy for photosynthesis and as a source of environmental information perceived by photoreceptors....
The ability of plants to adapt to changing light conditions depends on a protein kinase network in the chloroplast that...
The best in science news, commentary, and research
Show articles…On 28 December, two biochemistry Ph.D. students burned to death in a mysterious fire in India's main nuclear laboratory, the Bhabha Atomic Research Centre in Mumbai. A month earlier, dozens of workers at a nuclear plant in Kaiga were exposed to tritium in an apparent case of attempted poisoning.Author: Pallava Bagla
http://www.sciencemag.org/cgi/content/full/327/5962/133-a?rss=1
The show includes parent-offspring conflict in birds, peace through vaccine diplomacy, ocean versus land biodiversity, and more.
http://www.sciencemag.org/cgi/content/full/327/5971/1395-b?rss=1
A weekly roundup of information on newly offered instrumentation, apparatus, and laboratory materials of potential interest to researchers.
http://www.sciencemag.org/cgi/content/full/327/5971/1395-a?rss=1
Bacterial ammonia and formaldehyde production requires prior processing of a dehydrogenase to form a cofactor.Authors: Lyndal M. R. Jensen, Ruslan Sanishvili, Victor L. Davidson, Carrie M. Wilmot
http://www.sciencemag.org/cgi/content/full/327/5971/1392?rss=1
Mechanical forces acting on a cell-surface receptor affect the activation of a signaling pathway involved in breast cancer.Authors: Khalid Salaita, Pradeep M. Nair, Rebecca S. Petit, Richard M. Neve, Debopriya Das, Joe W. Gray, Jay T. Groves
http://www.sciencemag.org/cgi/content/full/327/5971/1380?rss=1
Methods recently developed for taxonomic analysis are fast and do not compromise accuracy.Author: Sebastien Roch
http://www.sciencemag.org/cgi/content/full/327/5971/1376?rss=1
Prenatal hormonal signaling can match a mother bird’s capacity to provide food with her offsprings’ expectations.Authors: Camilla A. Hinde, Rufus A. Johnstone, Rebecca M. Kilner
http://www.sciencemag.org/cgi/content/full/327/5971/1373?rss=1
The concentration of electrochemically active species on a gold electrode provides a local measurement of current density.Authors: Xiaonan Shan, Urmez Patel, Shaopeng Wang, Rodrigo Iglesias, Nongjian Tao
http://www.sciencemag.org/cgi/content/full/327/5971/1363?rss=1
The linear and nonlinear elastic responses near a growing crack tip can reveal how materials fail.Authors: Ariel Livne, Eran Bouchbinder, Ilya Svetlizky, Jay Fineberg
http://www.sciencemag.org/cgi/content/full/327/5971/1359?rss=1
Optical scattering is used to induce quantum coupling between light and an artificial atom.Authors: Luca Sapienza, Henri Thyrrestrup, Søren Stobbe, Pedro David Garcia, Stephan Smolka, Peter Lodahl
http://www.sciencemag.org/cgi/content/full/327/5971/1352?rss=1
Biophotonics International delivers a unique global insight into the photonic products and techniques that solve problems for researchers, product developers, clinical users, physicians and others actively involved in the fields of medicine, biology and biotechnology.
Show articles…Published since 1965, Laser Focus World - a monthly magazine for engineers, researchers, scientists, and technical professionals - provides comprehensive global coverage of optoelectronic technologies, applications, and markets. Nearly 70,000 qualified optoelectronics professionals from around the world currently subscribe.
Show articles…Bio-Optics World is a bi-monthly magazine that provides news, analysis and explanation of applications involving lasers, optics and imaging systems in the life sciences. The magazine is dedicated to giving readers a firsthand look at cutting-edge research related to the design, development and utilization of optical technologies in the study, diagnosis and treatment of disease and disease processes.
Show articles…IOHS serves as an international forum for the publication of the latest developments in all areas of photonics in biology and medicine. JIOHS will consider for publication original papers in all disciplines of photonics in biology and medicine, including but not limited to: photonic therapeutics and diagnostics; optical clinical technologies and systems; tissue optics; laser-tissue interaction and tissue engineering; biomedical spectroscopy; advanced microscopy and imaging; nanobiophotonics and optical moecular imaging; multimodal and hybrid biomedical imaging; micro/nanofabrication; medical microsystems; optical coherence tomography; photodynamic therapy.
Show articles…The German-language magazine "BioPhotonik - Optical technologies in Life Sciences" is dedicated to photonics topics in biology and medicine offering a platform to developers and suppliers of relevant products, such as medical systems, microscopes, spectroscopic systems, fluorescence products, dies, excitation lasers or optical components. "BioPhotonik" is published twice a year in March and September (circulation 10,000).
Show articles…Beim Laserlöten ist das Arbeitsfenster zwischen Schmelztemperatur und Überhitzung des Lotes sehr eng begrenzt. Gleichzeitig führt die schwankende Absorption unregelmäßiger Oberflächen und die variierende Wärmeableitung komplexer Bauteilgeometrien zu großen Temperaturschwankungen am Werkstück. Ein hierfür geeignetes Mess- und Regelsystem muss die Laserleistung extrem schnell an die relativ niedrigen Weichlöt-Temperaturen anpassen können, um reproduzierbar eine hohe Bearbeitungsqualität zu gewährleisten.
Mit dem Industriepartner neoLASE hat das LZH ein Lasersystem entwickelt, das sich mittels iPhone steuern und überwachen lässt.
Bislang haben die komplizierte Handhabung, hohe Investitions-kosten und die geringe mittlere Leistung eine breite industrielle Nutzung von Femtosekunden-Strahlquellen verhindert. Im Rahmen des BMBF-geförderten FEMTONIK-Forschungsprojekts FULMINA sollen diese Hürden überwunden werden.
Tagungsort 2010: die Goethe- und Optikstadt Wetzlar
Metamaterialien sind künstliche Strukturen, die elektromagnetische Wellen also auch Licht auf unnatürliche Weise manipulieren können. Theoretisch werden z.B. perfekte Linsen ohne Abbildungsfehler möglich. Erstmals wurden jetzt 3D-Metamaterialien beschrieben, die tatsächlich in der Spektroskopie Anwendung finden könnten.
Wissenschaftler von MPQ und Caltech demonstrieren an einzelnen schwingenden Ionen ein mechanisches Analogon zum optischen Laser.
Sind Elektronen in Nanostrukturen eingeschlossen, so zeigen sie Eigenschaften, die u.a. für neuartige Halbleiterlaser oder die Quanteninformationsverarbeitung genutzt werden könnten.
Physiker der Universität Bonn haben kürzlich Quantensprünge sichtbar gemacht. Dazu nutzten sie ein einzelnes Caesium-Atom als Lichtschalter zwischen zwei Spiegeln.
Für die Bildaufnahme bewegter Objekte wird seit langer Zeit das TDI-Verfahren (time delay integration) genutzt, denn durch Synchronisation der Pixel mit der Bewegung von Kamera oder Objekt lässt sich die effektive Belichtungszeit verlängern, ohne dass das Bild unscharf wird. Die analoge TDI-Implementierung in CMOS-Technik scheitert am fehlenden Mechanismus zur Ladungsaddition. Ein neuartiger Architekturansatz mit Schlitzverschluss und digitaler Addition kann als tragfähige Alternative CMOS-Sensoren mit TDI-Funktionen ausstatten.
Die genaue und schnelle Fokussierung von Proben über einen weiten XY Verfahrweg ist ein zentrales Problem in der industriellen Mikroskopie, z.B. bei der Inspektion von Wafern, Schleifproben oder anderen Präparaten. Neben der prinzipiellen Problematik der Autofokussierung werden hier Vor- und Nachteile von Soft- und Hardwarefokuseinrichtungen gegenübergestellt und das Prinzip eines neuentwickelten Hardware-Laserautofokus wird anhand eines Beispiels verdeutlicht.
Beschichtungen optischer Komponenten unterliegen zunehmenden Anforderungen an die präzise Einhaltung ihrer Spezifikationen sowie an ihre Reproduzierbarkeit und Zuverlässigkeit. Um dem Rechnung zu tragen, können moderne Beschichtungsverfahren wie z.B. das Ionenstrahlzerstäuben (IBS) eingeführt oder vorhandene Produktionsanlagen aufgerüstet werden. Im Folgenden werden verschiedene Techniken mit ihren Vor- und Nachteilen skizziert, außerdem wird am Beispiel einer optischen Breitband-Messtechnik die Bedeutung optimaler Prozesskontrolle demonstriert.
Die Bestimmung der Oberflächenqualität durch Sichtprüfung ist eine weit verbreitete Methode in der industriellen Fertigung, wenn die zugesicherten Eigenschaften technischer oder dekorativer Oberflächen nicht alleine durch den Fertigungsprozess gewährleistet sind. Im Folgenden wird ein Verfahren zur Oberflächenprüfung von 3D-Teilen vorgestellt, welches die Effizienz und Qualität im Prüfprozess steigern kann.
LEDs sind effizienter als Glühlampen und setzen ca. 30% der elektrischen Energie in Licht um aber immer noch 70% in Wärme. Diese muss abgeführt werden, denn hohe Temperaturen beeinträchtigen die Lebensdauer des Halbleiters und verändern seine Eigenschaften. Wir betrachten im Folgenden die thermischen Aspekte von LEDs und vergleichen verschiedene Wärmeleitmaterialien.
Der Messkopf zur Nachbildung der wesentlichen menschlichen Sehfunktionen dient zur objektiven Prüfung der Eigenschaften
Die räumlichen Lichtmodulatoren (SLM) der Serie X10468 LCOS (liquid crystal on silicon) decken einen Spektralbereich von
Zwei neue Kameramodelle der EVI-Serie von Sony ermöglichen bei durchschnittlichen Breitband-Übertragungsraten hochauflös
Zur Untersuchung histologischer Proben in Pathologie, Forschung und Lehre bietet der neue Slide Scanner SCN400 eine Alte
Das neue Modell CCS Prima 4 der Sensorfamilie CCS point ist mit vier Multiplexkanälen ausgestattet und erlaubt dami
Der neue PowerLine-Laser GPL von StockerYale Lasiris erzeugt eine mikrometerfeine grüne Laserlinie mit homogen verteilte
Die ergonomisch geformten Brillengestelle von Univet mit patentierten Bügeln passen sich mit ihrer gekrümmten Form optim
Die gemultiplexten 256-Element-Zeilenarrays von CAL Sensors wurden um die peltiergekühlten Modelle Lira5S für Wärmebilda
Der optische Durchgangsprüfer Fiberpoint ET (Easy Touch) deckt Fehler in Lichtwellenleitern auf. Die optische Leistung b
Die digitalen Hochgeschwindigkeits-Framegrabber der Phoenix HD-/SDI-Serie von Active Silicon wurden speziell für die Med
DUSA Pharmaceuticals Reports Full Year 2009 Corporate Highlights... (MalaysiaNews.net)
University Hospitals startup company opens in Akron (Akron Beacon Journal)
New treatments and good skin care helping patients control acne and rosacea (Science Daily)
Postdoctoral Scholars - Irvine, CA
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Biomedical Optics (BIOMED)-Editing event Biomed...
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