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Yujia Liu, Yiqing Lu, Xusan Yang, Xianlin Zheng, Shihui Wen, Fan Wang, Xavier Vidal, Jiangbo Zhao, Deming Liu, Zhiguang Zhou, Chenshuo Ma, Jiajia Zhou, James A Piper, Peng Xi, Dayong Jin
Lanthanide-doped glasses and crystals are attractive for laser applications because the metastable energy levels of the trivalent lanthanide ions facilitate the establishment of population inversion and amplified stimulated emission at relatively low pump power. At the nanometre scale, lanthanide-doped upconversion nanoparticles (UCNPs) can now be made with precisely controlled phase, dimension and doping level. When excited in the near-infrared, these UCNPs emit stable, bright visible luminescence at a variety of selectable wavelengths, with single-nanoparticle sensitivity, which makes them suitable for advanced luminescence microscopy applications...
February 22, 2017: Nature
Hugo Cruz, Hong-Yi Huang, Ching-Hsing Luo, Shuenn-Yuh Lee
This paper presents a 10-channel time-of-flight application-specific integrated circuit (ASIC) for positron emission tomography in a 90 nm standard CMOS process. To overcome variations in channel-to-channel timing resolution caused by mismatch and process variations, adaptive biases and a digital-to-analog converter (DAC) are utilized. The main contributions of this work are as follows. First, multistage architectures reduce the total power consumption, and detection bandwidths of analog preamplifiers and comparators are increased to 1 and 1...
February 13, 2017: IEEE Transactions on Biomedical Circuits and Systems
Kamran Karimi, Ezequiel E Ferrero, Jean-Louis Barrat
By means of a finite elements technique we solve numerically the dynamics of an amorphous solid under deformation in the quasistatic driving limit. We study the noise statistics of the stress-strain signal in the steady-state plastic flow, focusing on systems with low internal dissipation. We analyze the distributions of avalanche sizes and durations and the density of shear transformations when varying the damping strength. In contrast to avalanches in the overdamped case, dominated by the yielding point universal exponents, inertial avalanches are controlled by a nonuniversal damping-dependent feedback mechanism, eventually turning negligible the role of correlations...
January 2017: Physical Review. E
Gary J Gibson, Maozhou Yang
CRISPR/Cas9 genome editing technology has taken the research world by storm since its use in eukaryotes was first proposed in 2012. Publications describing advances in technology and new applications have continued at an unrelenting pace since that time. In this Review, we discuss the application of CRISPR/Cas9 for creating gene mutations - the application that initiated the current avalanche of interest - and new developments that have largely answered initial concerns about its specificity and ability to introduce new gene sequences...
February 9, 2017: Nature Reviews. Rheumatology
Yu Shang, Ting Li, Guoqiang Yu
Near-infrared (NIR) light enables the deep tissue investigation of microvascular hemodynamics. Blood flow is one such available observable promoting a wealth of physiological insight both individually and in combination with other metrics. Diffuse correlation spectroscopy (DCS) and, to a lesser extent, diffuse correlation tomography (DCT), have received interest over the past two decades as noninvasive methods for tissue blood flow measurement and imaging. DCS employs coherent point-illumination NIR light to penetrate deep tissues and commonly uses avalanche photodiodes to detect temporal speckle fluctuations of the diffuse light in a single speckle area of tissue surface, which are sensitive to the motions of red blood cells in the microvasculature of the detected tissue volume...
February 15, 2017: Physiological Measurement
Michael Bell, Timothy Krentz, J Keith Nelson, Linda Schadler, Ke Wu, Curt Breneman, Su Zhao, Henrik Hillborg, Brian Benicewicz
Adding nano-sized fillers to epoxy has proven to be an effective method for improving dielectric breakdown strength (DBS). Evidence suggests that dispersion state, as well as chemistry at the filler-matrix interface can play a crucial role in property enhancement. Herein we investigate the contribution of both filler dispersion and surface chemistry on the AC dielectric breakdown strength of silica-epoxy nanocomposites. Ligand engineering was used to synthesize bimodal ligands onto 15nm silica nanoparticles consisting of long epoxy compatible, poly(glycidyl methacrylate) (PGMA) chains, and short, π-conjugated, electroactive surface ligands...
February 4, 2017: Journal of Colloid and Interface Science
Dong-Ping Yang, Hai-Jun Zhou, Changsong Zhou
The brain is highly energy consuming, therefore is under strong selective pressure to achieve cost-efficiency in both cortical connectivities and activities. However, cost-efficiency as a design principle for cortical activities has been rarely studied. Especially it is not clear how cost-efficiency is related to ubiquitously observed multi-scale properties: irregular firing, oscillations and neuronal avalanches. Here we demonstrate that these prominent properties can be simultaneously observed in a generic, biologically plausible neural circuit model that captures excitation-inhibition balance and realistic dynamics of synaptic conductance...
February 13, 2017: PLoS Computational Biology
Kevin C Elliott, Wei Wu, Richard Bertram, Richard L Hyson, Frank Johnson
Neural activity within the cortical premotor nucleus HVC (acronym is name) encodes the learned songs of adult male zebra finches (Taeniopygia guttata). HVC activity is driven and/or modulated by a group of five afferent nuclei (the Medial Magnocellular nucleus of the Anterior Nidopallium, MMAN; Nucleus Interface, NIf; nucleus Avalanche, Av; the Robust nucleus of the Arcopallium, RA; the Uvaeform nucleus, Uva). While earlier evidence suggested that HVC receives a uniformly distributed and non-topographic pattern of afferent input, recent evidence suggests this view is incorrect (Basista et al...
February 11, 2017: Journal of Comparative Neurology
David Taylor-Robinson, Anna Pallecaros, Patrick Horner
Making a prompt and accurate diagnosis of genital tract infections is the key to instituting appropriate treatment and the linchpin of sexually transmitted infection control. We present a brief history, not covering syphilis, of diagnostic events for each of six bacteria and one protozoan from the time of discovery up to the molecular revolution. The latter is touched upon but its impact will form the substance of a further presentation. Here, hindsight is helpful in understanding the way in which progress was made over 135 years, often when microbiology, not even seen as a distinct discipline, had a difficult time in providing what was required in terms of dependable diagnostic techniques...
January 1, 2017: International Journal of STD & AIDS
Maria Antonelli, Irving Kushner
Inflammation has been defined for many years as the response to tissue injury and infection. We are now forced to reconsider this definition by the avalanche of reports that molecules and cells associated with inflammation are activated or expressed in high concentration in a large variety of states in the absence of tissue injury or infection. Modest increases in concentration of C-reactive protein, a circulating marker of inflammation, have been reported to be associated with an astounding number of conditions and lifestyles felt to be associated with poor health; these conditions represent or reflect minor metabolic stresses...
February 8, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Lena Mertens, Matthias Sonnleitner, Jonathan Leach, Megan Agnew, Miles J Padgett
We report an algorithm for reconstructing images when the average number of photons recorded per pixel is of order unity, i.e. photon-sparse data. The image optimisation algorithm minimises a cost function incorporating both a Poissonian log-likelihood term based on the deviation of the reconstructed image from the measured data and a regularization-term based upon the sum of the moduli of the second spatial derivatives of the reconstructed image pixel intensities. The balance between these two terms is set by a bootstrapping technique where the target value of the log-likelihood term is deduced from a smoothed version of the original data...
February 7, 2017: Scientific Reports
Tianqi Mao, Zhaocheng Wang, Qi Wang
Single-photon avalanche diode (SPAD) is a promising photosensor because of its high sensitivity to optical signals in weak illuminance environment. Recently, it has drawn much attention from researchers in visible light communications (VLC). However, existing literature only deals with the simplified channel model, which only considers the effects of Poisson noise introduced by SPAD, but neglects other noise sources. Specifically, when an analog SPAD detector is applied, there exists Gaussian thermal noise generated by the transimpedance amplifier (TIA) and the digital-to-analog converter (D/A)...
January 23, 2017: Optics Express
M Cortesi, S Rost, W Mittig, Y Ayyad-Limonge, D Bazin, J Yurkon, A Stolz
The operating principle and performances of the Multi-layer Thick Gaseous Electron Multiplier (M-THGEM) are presented. The M-THGEM is a novel hole-type gaseous electron multiplier produced by multi-layer printed circuit board technology; it consists of a densely perforated assembly of multiple insulating substrate sheets (e.g., FR-4), sandwiched between thin metallic-electrode layers. The electron avalanche processes occur along the successive multiplication stages within the M-THGEM holes, under the action of strong dipole fields resulting from the application of suitable potential differences between the electrodes...
January 2017: Review of Scientific Instruments
Stuart P Wilson
A thermodynamic model of thermoregulatory huddling interactions between endotherms is developed. The model is presented as a Monte Carlo algorithm in which animals are iteratively exchanged between groups, with a probability of exchanging groups defined in terms of the temperature of the environment and the body temperatures of the animals. The temperature-dependent exchange of animals between groups is shown to reproduce a second-order critical phase transition, i.e., a smooth switch to huddling when the environment gets colder, as measured in recent experiments...
January 2017: PLoS Computational Biology
Harikumar K Chandrasekharan, Frauke Izdebski, Itandehui Gris-Sánchez, Nikola Krstajić, Richard Walker, Helen L Bridle, Paul A Dalgarno, William N MacPherson, Robert K Henderson, Tim A Birks, Robert R Thomson
When an optical pulse propagates along an optical fibre, different wavelengths travel at different group velocities. As a result, wavelength information is converted into arrival-time information, a process known as wavelength-to-time mapping. This phenomenon is most cleanly observed using a single-mode fibre transmission line, where spatial mode dispersion is not present, but the use of such fibres restricts possible applications. Here we demonstrate that photonic lanterns based on tapered single-mode multicore fibres provide an efficient way to couple multimode light to an array of single-photon avalanche detectors, each of which has its own time-to-digital converter for time-correlated single-photon counting...
January 25, 2017: Nature Communications
Chirag C Sthalekar, Yun Miao, Valencia Joyner Koomson
An interface circuit with signal processing and digitizing circuits for a high frequency, large area avalanche photodiode (APD) has been integrated in a 130 nm BiCMOS chip. The system enables the absolute oximetry of tissue using frequency domain Near Infrared Spectroscopy (fdNIRS). The system measures the light absorbed and scattered by the tissue by measuring the reduction in the amplitude of signal and phase shift introduced between the light source and detector which are placed a finite distance away from each other...
September 22, 2016: IEEE Transactions on Biomedical Circuits and Systems
Wieslaw Strek, Robert Tomala, Mikolaj Lukaszewicz, Bartlomiej Cichy, Yuriy Gerasymchuk, Pawel Gluchowski, Lukasz Marciniak, Artur Bednarkiewicz, Dariusz Hreniak
Laser induced white light emission was observed from porous graphene foam irradiated with a focused continuous wave beam of the infrared laser diode. It was found that the intensity of the emission increases exponentially with increasing laser power density, having a saturation level at ca. 1.5 W and being characterized by stable emission conditions. It was also observed that the white light emission is spatially confined to the focal point dimensions of the illuminating laser light. Several other features of the laser induced white light emission were also discussed...
January 23, 2017: Scientific Reports
Kees Graamans
In the Netherlands, nasopharyngeal radium irradiation was started in 1945. The indications included refractory symptoms of otitis media with effusion and other adenoid-related disorders after adenoidectomy. It was considered a safe and effective therapy. Its use decreased sharply in 1958, following a worldwide media avalanche around the dramatic events in the treatment of a 5-year-old child in Utrecht, enhancing the widespread fear of radioactivity. This case history illustrates the powerful role of the media in medical decision-making...
February 2017: International Journal of Pediatric Otorhinolaryngology
Karlynn E Neu, Qingming Tang, Patrick C Wilson, Aly A Khan
Single-cell genomics offers powerful tools for studying immune cells, which make it possible to observe rare and intermediate cell states that cannot be resolved at the population level. Advances in computer science and single-cell sequencing technology have created a data-driven revolution in immunology. The challenge for immunologists is to harness computing and turn an avalanche of quantitative data into meaningful discovery of immunological principles, predictive models, and strategies for therapeutics...
January 13, 2017: Trends in Immunology
Jun Chen, Zhengyu Zhang, Min Zhu, Jintong Xu, Xiangyang Li
In this paper, we report a two-dimensional (2D) simulation for InGaAs/InAlAs separate absorption, grading, charge, and multiplication avalanche photodiodes (SAGCM APDs) and study the effect of the charge layer and multiplication layer on the operating voltage ranges of APD. We find that with the increase of the thicknesses as well as the doping concentrations of the charge layer and the multiplication layer, the punchthrough voltage increases; with the increase of the doping concentrations of two layers and the thickness of the charge layer, the breakdown voltage decreases; with the increase of the thickness of the multiplication layer, the breakdown voltage first rapidly declines and then slightly rises...
December 2017: Nanoscale Research Letters
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