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Maksim A Smirnov, Nikolay S Perminov, Raoul R Nigmatullin, Anvar A Talipov, Sergey A Moiseev
Single-photon detectors based on avalanche photodiodes (SPADs) are key elements of many modern highly sensitive optical systems. One of the bottlenecks of such detectors is an afterpulsing effect, which limits detection rate and requires an optimal hold-off time. In this paper, we propose a novel approach for statistical analysis of SPAD dark counts, and we demonstrate its usefulness for the search of the experimental condition where the afterpulsing effect can be strongly eliminated. This approach exploits a sequence of ranked time intervals between the dark counts and does not contain a complex mathematical analysis of the experimental data...
January 1, 2018: Applied Optics
Seigo Ito, Shigeyoshi Hiratsuka, Mitsuhiko Ohta, Hiroyuki Matsubara, Masaru Ogawa
We present our third prototype sensor and a localization method for Automated Guided Vehicles (AGVs), for which small imaging LIght Detection and Ranging (LIDAR) and fusion-based localization are fundamentally important. Our small imaging LIDAR, named the Single-Photon Avalanche Diode (SPAD) LIDAR, uses a time-of-flight method and SPAD arrays. A SPAD is a highly sensitive photodetector capable of detecting at the single-photon level, and the SPAD LIDAR has two SPAD arrays on the same chip for detection of laser light and environmental light...
January 10, 2018: Sensors
Madhav G Deo
A buzzword in Indian press and amongst the policy makers is that India is short of the WHO recommended doctor to population ratio of 1:1000. The recommendations were formulated to facilitate programs to achieve some of the health related UN-Millennium Development Goals (MDGs). Infections and malnutrition, which can be comfortably handled by a basic MBBS doctor, were the dominant health issues at the time of the formulation of the MDGs. However, all countries worldwide are going through health epidemiological transition and health impact of the non-communicable disorders (NCDs) can be no more ignored even by the low income nations...
October 2017: Journal of the Association of Physicians of India
Saurav Seshadri, Andreas Klaus, Daniel E Winkowski, Patrick O Kanold, Dietmar Plenz
Disturbed activity patterns in cortical networks contribute to the pathophysiology of schizophrenia (SZ). Several lines of evidence implicate NMDA receptor hypofunction in SZ, and blocking NMDA receptor signaling during early neurodevelopment produces cognitive deficits in rodent models that resemble those seen in schizophrenic patients. However, the altered network dynamics underlying these cognitive impairments largely remain to be characterized, especially at the cellular level. Here, we use in vivo two-photon calcium imaging to describe pathological dynamics, occurring in parallel with cognitive dysfunction, in a developmental NMDA receptor hypofunction model...
January 10, 2018: Translational Psychiatry
Nikolai Beev, Jonas Keller, Tanja E Mehlstäubler
We have developed an avalanche transistor-based pulse generator for driving the photocathode of an image intensifier, which comprises a mainly capacitive load on the order of 100 pF. The circuit produces flat-top pulses with a rise time of 2 ns, a FWHM of 10 ns, and an amplitude of tens of V at a high repetition rate in the range of tens of MHz. The generator is built of identical avalanche transistor sections connected in parallel and triggered in a sequence, synchronized to a reference rf signal. The described circuit and mode of operation overcome the power dissipation limit of avalanche transistor generators and enable a significant increase of pulse repetition rates...
December 2017: Review of Scientific Instruments
Mikko Hintikka, Lauri Hallman, Juha Kostamovaara
Timing walk error in pulsed time-of-flight based laser range finding was studied using two different types of laser diode drivers. The study compares avalanche bipolar junction transistor (BJT) and metal-oxide-semiconductor field-effect transistor switch based laser pulse drivers, both producing 1.35 ns current pulse length (full width at half maximum), and investigates how the slowly rising part of the current pulse of the avalanche BJT based driver affects the leading edge timing walk. The walk error was measured to be very similar with both drivers within an input signal dynamic range of 1:10 000 (receiver bandwidth of 700 MHz) but increased rapidly with the avalanche BJT based driver at higher values of dynamic range...
December 2017: Review of Scientific Instruments
The Lancet Respiratory Medicine
No abstract text is available yet for this article.
December 19, 2017: Lancet Respiratory Medicine
Giacomo Strapazzon, Peter Paal, Jürg Schweizer, Markus Falk, Benjamin Reuter, Kai Schenk, Hannes Gatterer, Katharina Grasegger, Tomas Dal Cappello, Sandro Malacrida, Lukas Riess, Hermann Brugger
Breathing under snow, e.g. while buried by a snow avalanche, is possible in the presence of an air pocket, but limited in time as hypoxia and hypercapnia rapidly develop. Snow properties influence levels of hypoxia and hypercapnia, but their effects on ventilation and oxygenation in humans are not fully elucidated yet. We report that in healthy subjects breathing into snow with an artificial air pocket, snow density had a direct influence on ventilation, oxygenation and exhaled CO2. We found that a rapid decline in O2 and increase in CO2 were mainly associated with higher snow densities and led to premature interruption due to critical hypoxia (SpO2 ≤ 75%)...
December 15, 2017: Scientific Reports
K Ehrlich, A Kufcsák, S McAughtrie, H Fleming, N Krstajic, C J Campbell, R K Henderson, K Dhaliwal, R R Thomson, M G Tanner
Full exploitation of fibre Raman probes has been limited by the obstruction of weak Raman signals by background fluorescence of the sample and the intrinsic Raman signal of the delivery fibre. Here we utilised functionalised gold nanoshells (NS) to take advantage of the surface-enhanced Raman spectroscopy (SERS) effect to enhance the pH responsive spectrum of 4-mercaptobenzoic acid (MBA). However, the fibre background is still dominant. Using the photon arrival time-resolving capability of a CMOS single-photon avalanche diode (SPAD) based line sensor, we recover the SERS spectrum without a fibre background in a 10 s measurement...
December 11, 2017: Optics Express
Wen-Hao Jiang, Jian-Hong Liu, Yin Liu, Ge Jin, Jun Zhang, Jian-Wei Pan
InGaAs/InP single-photon detectors (SPDs) are the key devices for applications requiring near-infrared single-photon detection. The gating mode is an effective approach to synchronous single-photon detection. Increasing gating frequency and reducing the module size are important challenges for the design of such a detector system. Here we present for the first time, to the best of our knowledge, an InGaAs/InP SPD with 1.25 GHz sine wave gating (SWG) using a monolithically integrated readout circuit (MIRC)...
December 15, 2017: Optics Letters
Yong Meng Sua, Heng Fan, Amin Shahverdi, Jia-Yang Chen, Yu-Ping Huang
Quantum correlated, highly non-degenerate photons can be used to synthesize disparate quantum nodes and link quantum processing over incompatible wavelengths, thereby constructing heterogeneous quantum systems for otherwise unattainable superior performance. Existing techniques for correlated photons have been concentrated in the visible and near-IR domains, with the photon pairs residing within one micron. Here, we demonstrate direct generation and detection of high-purity photon pairs at room temperature with 3...
December 13, 2017: Scientific Reports
Haris Riris, Kenji Numata, Stewart Wu, Brayler Gonzalez, Michael Rodriguez, Stan Scott, Stephan Kawa, Jianping Mao
We report on an airborne demonstration of atmospheric methane (CH4) measurements with an Integrated Path Differential Absorption (IPDA) lidar using an optical parametric amplifier (OPA) and optical parametric oscillator (OPO) laser transmitter and sensitive avalanche photodiode detector. The lidar measures the atmospheric CH4 absorption at multiple, discrete wavelengths near 1650.96 nm. The instrument was deployed in the fall of 2015, aboard NASA's DC-8 airborne laboratory along with an in-situ spectrometer and measured CH4 over a wide range of surfaces and atmospheric conditions from altitudes of 2 km to 13 km...
July 2017: Journal of Applied Remote Sensing
Zhonghua Kuang, Ziru Sang, Xiaohui Wang, Xin Fu, Ning Ren, Xianming Zhang, Yunfei Zheng, Qian Yang, Zhanli Hu, Junwei Du, Dong Liang, Xin Liu, Hairong Zheng, Yongfeng Yang
PURPOSE: The performance of current small animal PET scanners is mainly limited by the detector performance and depth encoding detectors are required to develop PET scanner to simultaneously achieve high spatial resolution and high sensitivity. Among all depth encoding PET detector approaches, dual-ended readout detector has the advantage to achieve the highest depth of interaction (DOI) resolution and spatial resolution. Silicon photomultiplier (SiPM) is believed to be the photodetector of the future for PET detector due to its excellent properties as compared to the traditional photodetectors such as photomultiplier tube (PMT) and avalanche photodiode (APD)...
December 9, 2017: Medical Physics
Yicheng Shi, Janet Zheng Jie Lim, Hou Shun Poh, Peng Kian Tan, Peiyu Amelia Tan, Alexander Ling, Christian Kurtsiefer
Quantum key distribution (QKD) at telecom wavelengths (1260 - 1625 nm) has the potential for fast deployment due to existing optical fibre infrastructure and mature telecom technologies. At these wavelengths, Indium Gallium Arsenide (InGaAs) avalanche photodiode (APD) based detectors are the preferred choice for photon detection. Similar to their Silicon counterparts used at shorter wavelengths, they exhibit fluorescence from recombination of electron-hole pairs generated in the avalanche breakdown process...
November 27, 2017: Optics Express
O Ramos, M Stojanova
No abstract text is available yet for this article.
November 3, 2017: Physical Review Letters
Sikandar Aftab, Muhammad Farooq Khan, Kyung-Ah Min, Ghazanfar Nazir, Amir Muhammad Afzal, Ghulam Dastgeer, Imtisal Akhtar, Yongho Seo, Suklyun Hong, Jonghwa Eom
P-N junctions represent the fundamental building blocks of most semiconductors for optoelectronic functions. This work demonstrates a technique for forming a WS<sub>2</sub>/Si van der Waals junction based on mechanical exfoliation. Multilayered WS<sub>2</sub> nanoflakes were exfoliated on the surface of bulk p-type Si substrates using a polydimethylsiloxane stamp. We found that the fabricated WS<sub>2</sub>/Si p-n junctions exhibited rectifying characteristics. We studied the effect of annealing processes on the performance of the WS<sub>2</sub>/Si van der Waals p-n junction and demonstrated that annealing improved its electrical characteristics...
December 1, 2017: Nanotechnology
Mohammad Dehghani-Habibabadi, Marzieh Zare, Farhad Shahbazi, Javad Usefie-Mafahim, Paolo Grigolini
The model of the current paper is an extension of a previous publication, wherein we have used the leaky integrate-and-fire model on a regular lattice with periodic boundary conditions, and introduced the temporal complexity as a genuine signature of criticality. In that work, the power-law distribution of neural avalanches was a manifestation of supercriticality rather than criticality. Here, however, we show that the continuous solution of the model and replacing the stochastic noise with a Gaussian zero-mean noise leads to the coincidence of power-law display of temporal complexity, and spatiotemporal patterns of neural avalanches at the critical point...
November 21, 2017: European Physical Journal. E, Soft Matter
James R Scheuermann, Adrian Howansky, Marc Hansroul, Sébastien Léveillé, Kenkichi Tanioka, Wei Zhao
PURPOSE: We present the first prototype Scintillator High Gain Avalanche Rushing Photoconductor Active Matrix Flat Panel Imager (SHARP-AMFPI). This detector includes a layer of avalanche amorphous Selenium (a-Se) (HARP) as the photoconductor in an indirect detector to amplify the signal and reduce the effects of electronic noise to obtain quantum noise limited images for low dose applications. It is the first time avalanche a-Se has been used in a solid-state imaging device and poses as a possible solution to eliminate the effects of electronic noise, which is crucial for low-dose imaging performance of AMFPI...
November 24, 2017: Medical Physics
Teruaki Enoto, Yuuki Wada, Yoshihiro Furuta, Kazuhiro Nakazawa, Takayuki Yuasa, Kazufumi Okuda, Kazuo Makishima, Mitsuteru Sato, Yousuke Sato, Toshio Nakano, Daigo Umemoto, Harufumi Tsuchiya
Lightning and thunderclouds are natural particle accelerators. Avalanches of relativistic runaway electrons, which develop in electric fields within thunderclouds, emit bremsstrahlung γ-rays. These γ-rays have been detected by ground-based observatories, by airborne detectors and as terrestrial γ-ray flashes from space. The energy of the γ-rays is sufficiently high that they can trigger atmospheric photonuclear reactions that produce neutrons and eventually positrons via β+ decay of the unstable radioactive isotopes, most notably 13N, which is generated via 14N + γ → 13N + n, where γ denotes a photon and n a neutron...
November 22, 2017: Nature
Elif Kaya, Matthias Totzeck, Tienush Rassaf
BACKGROUND: The pulsed electron avalanche knife (PEAK) PlasmaBlade™ is an innovative electrosurgical device that uses a novel technology to cut tissues. It has been proven to be safe and feasible in ear, nose, and throat surgery, but there are only limited data concerning the use of PlasmaBlade™ instead of conventional electrocautery in cardiac implantable electronic device (CIED) procedures except for generator replacements. METHODS: We conducted a retrospective, single-center study with patients undergoing CIED surgery at our center between December 2015 and March 2017 and evaluate the feasibility and the clinical outcome of the PlasmaBlade™...
November 21, 2017: European Journal of Medical Research
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