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J Patrick Coleman, Karin A Dahmen, Richard L Weaver
We study avalanches in the Kuramoto model, defined as excursions of the order parameter due to ephemeral episodes of synchronization. We present scaling collapses of the avalanche sizes, durations, heights, and temporal profiles, extracting scaling exponents, exponent relations, and scaling functions that are shown to be consistent with the scaling behavior of the power spectrum, a quantity independent of our particular definition of an avalanche. A comprehensive scaling picture of the noise in the subcritical finite-N Kuramoto model is developed, linking this undriven system to a larger class of driven avalanching systems...
April 2018: Physical Review. E
M Girardi-Schappo, M H R Tragtenberg
Power-law-shaped avalanche-size distributions are widely used to probe for critical behavior in many different systems, particularly in neural networks. The definition of avalanche is ambiguous. Usually, theoretical avalanches are defined as the activity between a stimulus and the relaxation to an inactive absorbing state. On the other hand, experimental neuronal avalanches are defined by the activity between consecutive silent states. We claim that the latter definition may be extended to some theoretical models to characterize their power-law avalanches and critical behavior...
April 2018: Physical Review. E
P G Baity, T Sasagawa, Dragana Popović
The dynamics of charge-ordered states is one of the key issues in underdoped cuprate high-temperature superconductors, but static short-range charge-order (CO) domains have been detected in almost all cuprates. We probe the dynamics across the CO (and structural) transition in La_{1.48}Nd_{0.4}Sr_{0.12}CuO_{4} by measuring nonequilibrium charge transport, or resistance R as the system responds to a change in temperature and to an applied magnetic field. We find evidence for metastable states, collective behavior, and criticality...
April 13, 2018: Physical Review Letters
Jan Buchholz, Jan Krieger, Claudio Bruschini, Samuel Burri, Andrei Ardelean, Edoardo Charbon, Jörg Langowski
Photon-counting sensors based on standard complementary metal-oxide-semiconductor single-photon avalanche diodes (SPADs) represent an emerging class of imagers that enable the counting and/or timing of single photons at zero readout noise (better than high-speed electron-multiplying charge-coupling devices) and over large arrays. They have seen substantial progress over the last 15 years, increasing their spatial resolution, timing accuracy, and sensitivity while reducing spurious signals such as afterpulsing and dark counts...
May 9, 2018: Biophysical Journal
L Sinha, M Fogarty, W Zhou, A Giudice, J G Brankov, K M Tichauer
Scattering of visible and near-infrared light in biological tissue reduces spatial resolution for imaging of tissues thicker than 100 μm. In this study, an optical projection imaging system is presented and characterized that exploits the dead-time characteristics typical of photon counting modules based on single photon avalanche diodes (SPADs). With this system, it is possible to attenuate the detection of more scattered late-arriving photons, such that detection of less scattered early-arriving photons can be enhanced with increased light intensity, without being impeded by the maximum count rate of the SPADs...
April 2018: Review of Scientific Instruments
D I Réfy, M Brix, R Gomes, B Tál, S Zoletnik, D Dunai, G Kocsis, S Kálvin, T Szabolics
Diagnostic alkali atom (e.g., lithium) beams are routinely used to diagnose magnetically confined plasmas, namely, to measure the plasma electron density profile in the edge and the scrape off layer region. A light splitting optics system was installed into the observation system of the lithium beam emission spectroscopy diagnostic at the Joint European Torus (JET) tokamak, which allows simultaneous measurement of the beam light emission with a spectrometer and a fast avalanche photodiode (APD) camera. The spectrometer measurement allows density profile reconstruction with ∼10 ms time resolution, absolute position calculation from the Doppler shift, spectral background subtraction as well as relative intensity calibration of the channels for each discharge...
April 2018: Review of Scientific Instruments
Seungjong Lee, Kyoungyoon Park, Hyuntai Kim, Luis Alonso Vazquez-Zuniga, Jinseob Kim, Yoonchan Jeong
We report the intermittent burst of a super rogue wave in the multi-soliton (MS) regime of an anomalous-dispersion fiber ring cavity. We exploit the spatio-temporal measurement technique to log and capture the shot-to-shot wave dynamics of various pulse events in the cavity, and obtain the corresponding intensity probability density function, which eventually unveils the inherent nature of the extreme events encompassed therein. In the breathing MS regime, a specific MS regime with heavy soliton population, the natural probability of pulse interaction among solitons and dispersive waves exponentially increases owing to the extraordinarily high soliton population density...
April 30, 2018: Optics Express
Longfei Xiao, Xianglong Yang, Peng Duan, Huayong Xu, Xiufang Chen, Xiaobo Hu, Yan Peng, Xiangang Xu
High-power photoconductive semiconductor switching devices were fabricated from a high-purity, semi-insulating 4H-SiC wafer. A highly n-doped GaN subcontact layer was inserted between the contact metal and the high-resistivity SiC wafer. The minimum ON-state resistance of the device was less than 1 ohm when the energy of a 355 nm laser was 10.5 mJ with a bias voltage of 6 kV. The maximum device lifetime is 3151 pulses, after which the device completely fails. The failure mechanisms are determined using several analysis methods...
April 10, 2018: Applied Optics
Xin Zhou, Jianfeng Sun, Peng Jiang, Di Liu, Qi Wang
The ranging performance for Geiger-mode avalanche photodiode (Gm-APD) laser detection and ranging (ladar) is mainly evaluated by range accuracy and precision; although Gm-APD ladar can evaluate the ranging performance of the exact position, it is not helpful to comprehensively evaluate the influence on the ranging of each parameter in the whole gate. Due to the target echo's stochastic trigger making the delay adjustment inaccurate, the position of the echo in the gate is stochastic in the actual detection process, so the theoretical calculation may not be able to make ladar ranging performance clear...
April 1, 2018: Applied Optics
Antoine Bérut, Hugo Chauvet, Valérie Legué, Bruno Moulia, Olivier Pouliquen, Yoël Forterre
Plants are able to sense and respond to minute tilt from the vertical direction of the gravity, which is key to maintain their upright posture during development. However, gravisensing in plants relies on a peculiar sensor made of microsize starch-filled grains (statoliths) that sediment and form tiny granular piles at the bottom of the cell. How such a sensor can detect inclination is unclear, as granular materials like sand are known to display flow threshold and finite avalanche angle due to friction and interparticle jamming...
April 30, 2018: Proceedings of the National Academy of Sciences of the United States of America
Ashwij Mayya, Anuradha Banerjee, R Rajesh
Haversian remodeling is known to result in improved resistance to compressive fracture in healthy cortical bone. Here, we examine the individual roles of the mean porosity, structure of the network of pores and remodeled bone matrix properties in the fracture behavior of Haversian bone. The detailed structure of porosity network is obtained both pre- and post-testing of dry cubical bone samples using micro-Computed Tomography. Based on the periodicity in the features of porosity along tangential direction, we develop a two dimensional porosity-based random spring network model for Haversian bone...
April 17, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Keith K Bolsen
Silage-related injury knows no age boundary as workers and bystanders of all ages have been killed in silage accidents. Even the best employee can become frustrated with malfunctioning equipment and poor weather conditions and take a hazardous shortcut, or misjudge a situation and take a risky action. At least 6 hazards are encountered in managing silage in bunker silos and drive-over piles that endanger lives: tractor or truck rollover, run-over by or entanglement in machinery, fall from height, crushing by an avalanche or collapsing silage, silage gases, and complacency or fatigue...
May 2018: Journal of Dairy Science
Amir H Atabaki, Sajjad Moazeni, Fabio Pavanello, Hayk Gevorgyan, Jelena Notaros, Luca Alloatti, Mark T Wade, Chen Sun, Seth A Kruger, Huaiyu Meng, Kenaish Al Qubaisi, Imbert Wang, Bohan Zhang, Anatol Khilo, Christopher V Baiocco, Miloš A Popović, Vladimir M Stojanović, Rajeev J Ram
Electronic and photonic technologies have transformed our lives-from computing and mobile devices, to information technology and the internet. Our future demands in these fields require innovation in each technology separately, but also depend on our ability to harness their complementary physics through integrated solutions1,2 . This goal is hindered by the fact that most silicon nanotechnologies-which enable our processors, computer memory, communications chips and image sensors-rely on bulk silicon substrates, a cost-effective solution with an abundant supply chain, but with substantial limitations for the integration of photonic functions...
April 2018: Nature
Bo Zhao, Yun-Sheng Wang, Yong-Hong Luo, Jia Li, Xin Zhang, Tong Shen
At 21.19 on 8 August 2017, an Ms 7.0 earthquake struck the Jiuzhaigou scenic spot in northwestern Sichuan Province, China. The Jiuzhaigou earthquake is a strike-slip earthquake with a focal depth of 20 km at 33.20° N and 103.82° E, and was caused by two concealed faults. According to emergency investigations and remote sensing interpretations, the Jiuzhaigou earthquake triggered 1780 landslides, damaged one dam (Nuorilang Waterfall) and broke one dam (Huohua Lake). The landslides mainly occurred in the Rize Valley and Shuzheng Valley and in Jiuzhai Paradise...
March 2018: Royal Society Open Science
David F C Hsu, David L Freese, Paul D Reynolds, Derek R Innes, Craig S Levin
We are developing a 1-mm3 resolution, high-sensitivity positron emission tomography (PET) system for loco-regional cancer imaging. The completed system will comprise two cm detector panels and contain 4 608 position sensitive avalanche photodiodes (PSAPDs) coupled to arrays of mm3 LYSO crystal elements for a total of 294 912 crystal elements. For the first time, this paper summarizes the design and reports the performance of a significant portion of the final clinical PET system, comprising 1 536 PSAPDs, 98 304 crystal elements, and an active field-of-view (FOV) of cm...
April 2018: IEEE Transactions on Medical Imaging
Antonino Ingargiola, Maya Segal, Angelo Gulinatti, Ivan Rech, Ivan Labanca, Piera Maccagnani, Massimo Ghioni, Shimon Weiss, Xavier Michalet
Single-molecule Förster resonance energy transfer (smFRET) allows measuring distances between donor and acceptor fluorophores on the 3-10 nm range. Solution-based smFRET allows measurement of binding-unbinding events or conformational changes of dye-labeled biomolecules without ensemble averaging and free from surface perturbations. When employing dual (or multi) laser excitation, smFRET allows resolving the number of fluorescent labels on each molecule, greatly enhancing the ability to study heterogeneous samples...
March 28, 2018: Journal of Chemical Physics
Mattias Olsson, Fredrik Edman, Khadga Jung Karki
An approximation to coherent sampling, also known as boot-strapped waveform averaging, is presented. The method uses digital cavities to determine the condition for coherent sampling. It can be used to increase the effective sampling rate of a repetitive signal and the signal to noise ratio simultaneously. The method is demonstrated by using it to directly measure the fluorescence lifetime from Rhodamine 6G by digitizing the signal from a fast avalanche photodiode. The obtained lifetime of 4.0 ns is in agreement with the known values...
March 2018: Review of Scientific Instruments
S A Díaz, C Reichhardt, D P Arovas, A Saxena, C J O Reichhardt
We show using numerical simulations that slowly driven Skyrmions interacting with random pinning move via correlated jumps or avalanches. The avalanches exhibit power-law distributions in their duration and size, and the average avalanche shape for different avalanche durations can be scaled to a universal function, in agreement with theoretical predictions for systems in a nonequilibrium critical state. A distinctive feature of Skyrmions is the influence of the nondissipative Magnus term. When we increase the ratio of the Magnus term to the damping term, a change in the universality class of the behavior occurs, the average avalanche shape becomes increasingly asymmetric, and individual avalanches exhibit motion in the direction perpendicular to their own density gradient...
March 16, 2018: Physical Review Letters
Ken Zafren, Dale Atkins, Hermann Brugger
We present a historical case of a 12-year-old boy who survived a reported avalanche burial in 1939 in the Upper Peninsula of Michigan. The boy was completely buried for at least 3 hours, head down, at a depth of about 1 m. He was extricated without signs of life and likely hypothermic by his father, who took him to his home. There, the father performed assisted ventilation for 3 hours using the Schäfer method, a historical method of artificial ventilation, without any specific rewarming efforts. The boy recovered neurologically intact...
March 26, 2018: Wilderness & Environmental Medicine
Francesco Ceccarelli, Angelo Gulinatti, Ivan Labanca, Massimo Ghioni, Ivan Rech
In this letter, the development and the experimental characterization of a new photon detection module, based on a 32×1 red-enhanced single-photon avalanche diode (RE-SPAD) array, are presented. A custom-developed technology has been exploited to design a detector having large-area pixels (50-µm diameter) with optimized performance. With an excess bias voltage Voυ = 15 V, a photon detection efficiency as high as 57% at 600 nm (33% at 800 nm) is achieved, along with dark count rate in the kHz range and optical crosstalk probability as low as 0...
March 15, 2018: IEEE Photonics Technology Letters: a Publication of the IEEE Laser and Electro-optics Society
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