Spectral dependency of superconducting single photon detectors

International audienceWe investigate the effect of varying both incoming optical wavelength and width of NbN nanowires on the superconducting single photondetectors (SSPD) detection efficiency. The SSPD are current biased close to critical value and temperature fixed at 4.2 K, far from transition. The experimental results are found to verify with a good accuracy predictions based on the "hot spot model," whose size scales with the absorbed photon energy. With larger optical power inducing multiphoton detection regime, the same scaling law remains valid, up to the three-photon regime. We demonstrate the validity of applying a limited number of measurements and using such a simple model to reasonably predict any SSPD behavior among a collection of nanowire device widths at different photon wavelengths. These results set the basis for designing efficient single photondetectors operating in the infrared (2-5 μm range)

COMPARISON OF SOLVING A STIFF EQUATION ON A SPHERE BY THE MULTI-LAYER METHOD AND METHOD OF CONTINUING AT THE BEST PARAMETER

A stiff equation, linked with the solution of singularly perturbed differential equations with the use of standard methods of numeral solutions of simple differential equations often lead to major difficulties. First difficulty is the loss of stability of the counting process, when small errors on separate steps lead to an increase in the systematic errors in general. Another difficulty is, directly linked with the first one, consists of the need of decreasing the integrating step by a lot, which leads to a major decrease in the time taken for the calculations. On an example of a boundary value problem for a differential equation of second power on a sphere, comparison of our two approaches of constructing approximate values are held. The first approach is connected with the construction of an approximate multi-layer solution of the problem and is based on the use of recurrent equalities, that come out from classical numeral methods to the interval of a non-constant length. As a result, a numeral, approximated solution is replaced with an approximate solution in form of a function, which is easier to use for adaptation, building a graph and other needs. The second approach is linked with the continuation of the solutions by the best parameter. This method allows us to decrease majorly the number of steps and increase the stability of the computing process compared to standard methods

Изомногообразия минимального флегмового числа для случая ректификации смеси хлороформ-бензол-толуол в режиме первого класса фракционирования

Using modern methods of mathematical modeling the minimum reflux ratio values were calculated for the wide range of initial compositions for the zeotropic chloroform-benzene-toluene mixture in the absence of α=1 manifolds and for the case of rectification in the mode of the first class fractionalization. The form, shape and location of minimum reflux ration lines are represented on the diagram for the considered mixture and conditions. Some analytical and graphical peculiarities and regularities were revealed in the course of the calculation.С использованием современных методов математического моделирования рассчитаны значения минимального флегмового числа для достаточно широкого диапазона исходных составов трехкомпонентной зеотропной смеси хлороформ-бензол-толуол, в которой отсутствуют единичные α-многообразия, для случая ректификации в режиме первого класса фракционирования. Получена диаграмма, на которой представлены вид, ход и положение изолиний минимального флегмового числа для выбранной смеси в указанных условиях. В ходе работы и проведенных расчетов были выявлены некоторые аналитические и геометрические особенности и закономерности

Особенности влияния относительной летучести компонентов на расчет и структуру диаграмм фазового равновесия жидкость-пар многокомпонентных смесей

The importance of relative volatility of components and α-manifolds closely associated with this magnitude for investigation and revelation of qualitative and quantitative regularities of rectification of multicomponent ideal and non-ideal zeotropic mixtures is shown.Показана важная роль, которую играют величина относительной летучести компонентов и связанные с ней единичные α-линии для исследования и выявления качественных и количественных закономер-ностей процесса ректификации многокомпонентных идеальных и неидеальных зеотропных смесей

EFSA's OpenFoodTox: An open source toxicological database on chemicals in food and feed and its future developments

Since its creation in 2002, the European Food Safety Authority (EFSA) has produced risk assessments for over 5000 substances in >2000 Scientific Opinions, Statements and Conclusions through the work of its Scientific Panels, Units and Scientific Committee. OpenFoodTox is an open source toxicological database, available both for download and data visualisation which provides data for all substances evaluated by EFSA including substance characterisation, links to EFSA's outputs, applicable legislations regulations, and a summary of hazard identification and hazard characterisation data for human health, animal health and ecological assessments. The database has been structured using OECD harmonised templates for reporting chemical test summaries (OHTs) to facilitate data sharing with stakeholders with an interest in chemical risk assessment, such as sister agencies, international scientific advisory bodies, and others. This manuscript provides a description of OpenFoodTox including data model, content and tools to download and search the database. Examples of applications of OpenFoodTox in chemical risk assessment are discussed including new quantitative structure–activity relationship (QSAR) models, integration into tools (OECD QSAR Toolbox and AMBIT-2.0), assessment of environmental footprints and testing of threshold of toxicological concern (TTC) values for food related compounds. Finally, future developments for OpenFoodTox 2.0 include the integration of new properties, such as physico-chemical properties, exposure data, toxicokinetic information; and the future integration within in silico modelling platforms such as QSAR models and physiologically-based kinetic models. Such structured in vivo, in vitro and in silico hazard data provide different lines of evidence which can be assembled, weighed and integrated using harmonised Weight of Evidence approaches to support the use of New Approach Methodologies (NAMs) in chemical risk assessment and the reduction of animal testing

High Speed and High Efficiency Travelling Wave Single-Photon Detectors Embedded in Nanophotonic Circuits

Ultrafast, high quantum efficiency single photon detectors are among the most sought-after elements in modern quantum optics and quantum communication. High photon detection efficiency is essential for scalable measurement-based quantum computation, quantum key distribution, and loophole-free Bell experiments. However, imperfect modal matching and finite photon absorption rates have usually limited the maximum attainable detection efficiency of single photon detectors. Here we demonstrate a superconducting nanowire detector atop nanophotonic waveguides which allows us to drastically increase the absorption length for incoming photons. When operating the detectors close to the critical current we achieve high on-chip single photon detection efficiency up to 91% at telecom wavelengths, with uncertainty dictated by the variation of the waveguide photon flux. We also observe remarkably low dark count rates without significant compromise of detection efficiency. Furthermore, our detectors are fully embedded in a scalable silicon photonic circuit and provide ultrashort timing jitter of 18ps. Exploiting this high temporal resolution we demonstrate ballistic photon transport in silicon ring resonators. The direct implementation of such a detector with high quantum efficiency, high detection speed and low jitter time on chip overcomes a major barrier in integrated quantum photonics

The Use of the Raabe Aspirator in Intraoperative neurophysiological Monitoring during Decompression and Stabilization Interventions for Degenerative Diseases and Injuries of the Lumbar Spine

Background. Raabe probe is a suction device with monopolar motor fibers mapping capabilities. A number of technical characteristics make it possible to use it for intraoperative neurophysiological monitoring during posterior lumbar fusion surgery.The aim of this study was to analyze our experience of Raabe probe using for intraoperative neurophysiological monitoring during posterior lumbar fusion surgery.Methods. Ninety-eight patients (55 women and 43 men) with degenerative changes and injuries of the lumbar spine were included into the study, mean age – 56.3 ± 12.8 years. Patients underwent the following operations: 85 cases (86.7 %) – spinal roots decompression with fusion by dorsal and ventral implants, 12 cases (12.2 %) – decompression with only dorsal fusion, 1 case (1.0 %) – dorsal fusion without decompression. In all cases intraoperative neurophysiological monitoring control by B. Calancie method with Raabe probe using was performed.Results. With a critical current threshold of 12 mA, the sensitivity of the method is 94 %, the specificity is 97 %. Comparing the thresholds of the M-response at the stage of screw stimulation, no statistically significant differences were found between the groups of true-positive and false-positive results, both for interested (p = 0.09) and intact (p = 0,16) screws. At the stage of the impactor stimulation, the threshold of the M-response in the true-positive group made11.39 ± 7.97 mA, and in the false-positive group – 24.16 ± 8.85 mA (p < 0.05).Conclusion. Raabe probe application for intraoperative neurophysiological monitoring during posterior lumbar fusion surgery show the high sensitivity and specificity. The most reliable sign of pedicle wall breach is a threshold below than 12 mA at the stage of the impactor stimulation