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Bojie Cong, Shizue Ohsawa, Tatsushi Igaki
Epithelial cancer tissues often possess polyploid giant cells, which are thought to be highly oncogenic. However, the mechanisms by which polyploid giant cells are generated in tumor tissues and how such cells contribute to tumor progression remain elusive. We previously noticed in Drosophila imaginal epithelium that cells mutant for the endocytic gene rab5 exhibit enlarged nuclei. Here we find that mutations in endocytic 'neoplastic tumor-suppressor' genes, such as rab5, vps25, erupted, or avalanche result in generation of polyploid giant cells...
March 14, 2018: Oncogene
J A Ballesteros-Cánovas, D Trappmann, J Madrigal-González, N Eckert, M Stoffel
Ongoing climate warming has been demonstrated to impact the cryosphere in the Indian Himalayas, with substantial consequences for the risk of disasters, human well-being, and terrestrial ecosystems. Here, we present evidence that the warming observed in recent decades has been accompanied by increased snow avalanche frequency in the Western Indian Himalayas. Using dendrogeomorphic techniques, we reconstruct the longest time series (150 y) of the occurrence and runout distances of snow avalanches that is currently available for the Himalayas...
March 13, 2018: Proceedings of the National Academy of Sciences of the United States of America
Ximing Ren, Peter W R Connolly, Abderrahim Halimi, Yoann Altmann, Stephen McLaughlin, Istvan Gyongy, Robert K Henderson, Gerald S Buller
A CMOS single-photon avalanche diode (SPAD) quanta image sensor is used to reconstruct depth and intensity profiles when operating in a range-gated mode used in conjunction with pulsed laser illumination. By designing the CMOS SPAD array to acquire photons within a pre-determined temporal gate, the need for timing circuitry was avoided and it was therefore possible to have an enhanced fill factor (61% in this case) and a frame rate (100,000 frames per second) that is more difficult to achieve in a SPAD array which uses time-correlated single-photon counting...
March 5, 2018: Optics Express
Lorenz Hruby, Nishant Dogra, Manuele Landini, Tobias Donner, Tilman Esslinger
We experimentally study the stability of a bosonic Mott insulator against the formation of a density wave induced by long-range interactions and characterize the intrinsic dynamics between these two states. The Mott insulator is created in a quantum degenerate gas of 87-Rubidium atoms, trapped in a 3D optical lattice. The gas is located inside and globally coupled to an optical cavity. This causes interactions of global range, mediated by photons dispersively scattered between a transverse lattice and the cavity...
March 8, 2018: Proceedings of the National Academy of Sciences of the United States of America
Liang Wang, Shaokun Han, Wenze Xia, Jieyu Lei
Although the Geiger-mode avalanche photodiode (GM-APD) flash ladar system offers the advantages of high sensitivity and simple construction, its detection performance is influenced not only by the incoming signal-to-noise ratio but also by the absolute number of noise photons. In this paper, we deduce a hyperbolic approximation to estimate the noise-photon number from the false-firing percentage in a GM-APD flash ladar system under dark conditions. By using this hyperbolic approximation function, we introduce a method to adapt the aperture to reduce the number of incoming background-noise photons...
February 2018: Review of Scientific Instruments
Hanna Napieczynska, Armin Kolb, Prateek Katiyar, Matteo Tonietto, Minhaz Ud-Dean, Ramona Stumm, Kristina Herfert, Carsten Calaminus, Bernd Pichler
The goal of this study was to validate the use of a magnetic resonance-compatible blood sampler (BS) with the detector system based on lutetium oxyorthosilicate scintillator and avalanche photodiodes for small animal positron emission tomography (PET). Methods: Five rats underwent a 60 min18 F-FDG study. For each animal, the arterial input function (AIF) was derived from the BS recording, from manual blood sampling (MS) and from the PET image. These AIFs were used for kinetic modelling of the striatum using the two tissue irreversible compartment model...
February 23, 2018: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
Lichun Meng, Andreas Fix, Martin Wirth, Lasse Høgstedt, Peter Tidemand-Lichtenberg, Christian Pedersen, Peter John Rodrigo
We demonstrate a robust, compact, portable and efficient upconversion detector (UCD) for a differential absorption lidar (DIAL) system designed for range-resolved methane (CH4 ) atmospheric sensing. The UCD is built on an intracavity pump system that mixes a 1064 nm pump laser with the lidar backscatter signal at 1646 nm in a 25-mm long periodically poled lithium niobate crystal. The upconverted signal at 646 nm is detected by a photomultiplier tube (PMT). The UCD with a noise equivalent power around 127 fW/Hz1/2 outperforms a conventional InGaAs based avalanche photodetector when both are used for DIAL measurements...
February 19, 2018: Optics Express
Dong Yuan, Wang Di, Wei Zhi, Fu Tai Ran
In this paper, an experimental study of silicon-based avalanche photodiode (Si-APD) with millisecond pulse laser irradiation was carried out, and the C-V curve of Si-APD was obtained by using a semiconductor analyzer. Based on the single-side abrupt junction character of n+p, combined with the corresponding theoretical derivation, the doping concentration varying with the axial depth of damaged Si-APD was obtained by inverse computation. The lattice dislocation and junction reduction were the fundamental causes of the reduced doping concentration...
February 10, 2018: Applied Optics
Mohammad Yaghoubi, Ty de Graaf, Javier G Orlandi, Fernando Girotto, Michael A Colicos, Jörn Davidsen
Neuronal avalanches have become an ubiquitous tool to describe the activity of large neuronal assemblies. The emergence of scale-free statistics with well-defined exponents has led to the belief that the brain might operate near a critical point. Yet not much is known in terms of how the different exponents arise or how robust they are. Using calcium imaging recordings of dissociated neuronal cultures we show that the exponents are not universal, and that significantly different exponents arise with different culture preparations, leading to the existence of different universality classes...
February 21, 2018: Scientific Reports
T A Lebedkina, D A Zhemchuzhnikova, M A Lebyodkin
Jerky flow in solids results from collective dynamics of dislocations which gives rise to serrated deformation curves and a complex evolution of the strain heterogeneity. A rich example of this phenomenon is the Portevin-Le Chatelier effect in alloys. The corresponding spatiotemporal patterns showed some universal features which provided a basis for a well-known phenomenological classification. Recent studies revealed peculiar features in both the stress serration sequences and the kinematics of deformation bands in Al-based alloys containing fine microstructure elements, such as nanosize precipitates and/or submicron grains...
January 2018: Physical Review. E
Jie Lin, Matthieu Wyart
The flow curve of various yield stress materials is singular as the strain rate vanishes and can be characterized by the so-called Herschel-Bulkley exponent n=1/β. A mean-field approximation due to Hebraud and Lequeux (HL) assumes mechanical noise to be Gaussian and leads to β=2 in rather good agreement with observations. Here we prove that the improved mean-field model where the mechanical noise has fat tails instead leads to β=1 with logarithmic correction. This result supports that HL is not a suitable explanation for the value of β, which is instead significantly affected by finite-dimensional effects...
January 2018: Physical Review. E
Djordje Spasojević, Svetislav Mijatović, Víctor Navas-Portella, Eduard Vives
We present extensive numerical studies of the crossover from three-dimensional to two-dimensional systems in the nonequilibrium zero-temperature random-field Ising model with metastable dynamics. Bivariate finite-size scaling hypotheses are presented for systems with sizes L×L×l which explain the size-driven critical crossover from two dimensions (l=const, L→∞) to three dimensions (l∝L→∞). A model of effective critical disorder R_{c}^{eff}(l,L) with a unique fitting parameter and no free parameters in the R_{c}^{eff}(l,L→∞) limit is proposed, together with expressions for the scaling of avalanche distributions bringing important implications for related experimental data analysis, especially in the case of thin three-dimensional systems...
January 2018: Physical Review. E
Marc Blancher, François Albasini, Fidel Elsensohn, Ken Zafren, Natalie Hölzl, Kyle McLaughlin, Albert R Wheeler, Steven Roy, Hermann Brugger, Mike Greene, Peter Paal
Blancher, Marc, François Albasini, Fidel Elsensohn, Ken Zafren, Natalie Hölzl, Kyle McLaughlin, Albert R. Wheeler III, Steven Roy, Hermann Brugger, Mike Greene, and Peter Paal. Management of multi-casualty incidents in mountain rescue. High Alt Med Biol. 00:000-000, 2018. INTRODUCTION: Multi-Casualty Incidents (MCI) occur in mountain areas. Little is known about the incidence and character of such events, and the kind of rescue response. Therefore, the International Commission for Mountain Emergency Medicine (ICAR MEDCOM) set out to provide recommendations for the management of MCI in mountain areas...
February 15, 2018: High Altitude Medicine & Biology
Sanja Janićević, Dragutin Jovković, Lasse Laurson, Djordje Spasojević
We present a numerical study of the correlations in the occurrence times of consecutive crackling noise events in the nonequilibrium zero-temperature Random Field Ising model in three dimensions. The critical behavior of the system is portrayed by the intermittent bursts of activity known as avalanches with scale-invariant properties which are power-law distributed. Our findings, based on the scaling analysis and collapse of data collected in extensive simulations show that the observed correlations emerge upon applying a finite threshold to the pertaining signals when defining events of interest...
February 7, 2018: Scientific Reports
Javier Diaz, Alejandro Bassi, Alex Coolen, Ennio A Vivaldi, Juan-Carlos Letelier
Traditionally, EEG is understood as originating from the synchronous activation of neuronal populations that generate rhythmic oscillations in specific frequency bands. Recently, new neuronal dynamics regimes have been identified (e.g. neuronal avalanches) characterized by irregular or arrhythmic activity. In addition, it is starting to be acknowledged that broadband properties of EEG spectrum (following a 1/f law) are tightly linked to brain function. Nevertheless, there is still no theoretical framework accommodating the coexistence of these two EEG phenomenologies: rhythmic/narrowband and arrhythmic/broadband...
February 1, 2018: NeuroImage
Heiko Hoffmann, David W Payton
Self-organized criticality (SOC) is a phenomenon observed in certain complex systems of multiple interacting components, e.g., neural networks, forest fires, and power grids, that produce power-law distributed avalanche sizes. Here, we report the surprising result that the avalanches from an SOC process can be used to solve non-convex optimization problems. To generate avalanches, we use the Abelian sandpile model on a graph that mirrors the graph of the optimization problem. For optimization, we map the avalanche areas onto search patterns for optimization, while the SOC process receives no feedback from the optimization itself...
February 5, 2018: Scientific Reports
Yingjie Ma, Yonggang Zhang, Yi Gu, Yanhui Shi, Xingyou Chen, Wanyan Ji, Ben Du, Xiumei Shao, Jiaxiong Fang
We report an electron-initiated 1064 nm InGaAsP avalanche photodetectors (APDs) with an InAlAs multiplier. By utilizing a tailored digital alloy superlattice grading structure, a charge layer and a p type InAlAs multiplier, an unity gain quantum efficiency of 48%, a low room temperature dark current of 470 pA at 90% breakdown voltage, and a low multiplication noise with an effective k ratio of ∼0.2 are achieved. The measured maximum gain factor is 5 at room temperature, which is currently limited by the non-optimized electric field profiles, and can be readily enhanced by modifying the doping and thickness parameters for the multiplier and the charge layer...
January 22, 2018: Optics Express
Lucas L G Pinel, Simon J Dimler, Xinxin Zhou, Salman Abdullah, Shiyong Zhang, Chee Hing Tan, Jo Shien Ng
Avalanche photodiodes (APDs) with thin avalanche regions have shown low excess noise characteristics and high gain-bandwidth products, so they are suited for long-haul optical communications. In this work, we investigated how carrier injection profile affects the avalanche gain and excess noise factors of Al0.85Ga0.15As0.56Sb0.44 (lattice-matched to InP substrates) p-i-n and n-i-p diodes with total depletion widths of 145-240 nm. Different carrier injection profiles were achieved by using light with wavelengths of 420, 543 and 633nm...
February 5, 2018: Optics Express
Matthew J Hobbs, Matthew P Grainger, Chengxi Zhu, Chee Hing Tan, Jonathan R Willmott
Accurate quantitative temperature measurements are difficult to achieve using focal-plane array sensors. This is due to reflections inside the instrument and the difficulty of calibrating a matrix of pixels as identical radiation thermometers. Size-of-source effect (SSE), which is the dependence of an infrared temperature measurement on the area surrounding the target area, is a major contributor to this problem and cannot be reduced using glare stops. Measurements are affected by power received from outside the field-of-view (FOV), leading to increased measurement uncertainty...
February 5, 2018: Optics Express
Meiwei Kong, Yifei Chen, Rohail Sarwar, Bin Sun, Zhiwei Xu, Jun Han, Jiawang Chen, Huawei Qin, Jing Xu
In this work, we propose an underwater wireless optical communication (UWOC) system using an arrayed transmitter/receiver and optical superimposition-based pulse amplitude modulation with 4 levels (PAM-4). At the transmitter side, we design a spatial summing scheme using a light emitting diode (LED) array, which is divided into two groups in a uniformly interleaved manner. With on-off keying (OOK) modulation for each group, optical superimposition-based PAM-4 can be realized. It has enhanced tolerance to the modulation nonlinearities of LEDs...
February 5, 2018: Optics Express
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