Development of high-gain gaseous photomultipliers for the visible spectral range

We summarize the development of visible-sensitive gaseous photomultipliers, combining a semitransparent bi-alkali photocathode with a state-of-the-art cascaded electron multiplier. The latter has high photoelectron collection efficiency and a record ion blocking capability. We describe in details the system and methods of photocathode production and characterization, their coupling with the electron multiplier and the gaseous-photomultiplier operation and characterization in a continuous mode. We present results on the properties of laboratory-produced K$_2$CsSb, Cs$_3$Sb and Na$_2$KSb photocathodes and report on their stability and QE in gas; K$_2$CsSb photocathodes yielded QE values in Ar/CH$_4$(95/5) above 30% at wavelengths of 360-400 nm. The novel gaseous photomultiplier yielded stable operation at gains of 10$^5$, in continuous operation mode, in 700 Torr of this gas; its sensitivity to single photons was demonstrated. Other properties are described. The successful detection of visible light with this gas-photomultiplier pave ways towards further development of large-area sealed imaging detectors, of flat geometry, insensitive to magnetic fields, which might have significant impact on light detection in numerous fields.Comment: 22 pages, 12 figures, for submission to JINS

A Comparative Numerical Study on GEM, MHSP and MSGC

In this work, we have tried to develop a detailed understanding of the physical processes occurring in those variants of Micro Pattern Gas Detectors (MPGDs) that share micro hole and micro strip geometry, like GEM, MHSP and MSGC etc. Some of the important and fundamental characteristics of these detectors such as gain, transparency, efficiency and their operational dependence on different device parameters have been estimated following detailed numerical simulation of the detector dynamics. We have used a relatively new simulation framework developed especially for the MPGDs that combines packages such as GARFIELD, neBEM, MAGBOLTZ and HEED. The results compare closely with the available experimental data. This suggests the efficacy of the framework to model the intricacies of these micro-structured detectors in addition to providing insight into their inherent complex dynamical processes

Динаміка електричної активності головного мозку при активації сенсорного апарата швколових каналів

For an estimation of dynamics of electrical activity of human brain the EEG record was carried out in a background régime (conducted at closed eyes of inspected persons) and at superposition of afferent irritant agents by the way of stimulations of semicircular channels and light stimulation (eye discovering). The relation between amplitude and frequency of cérébral rhythms in condition of relative physiological rest and at boring of vestibular and Visual receptors was revealedДля оцінки динаміки електричної активності головного мозку проводився запис ЕЕГ у фоновому режимі (при закритих очах обстежуваних) і при пред'явленні аферентних подразників у виді стимуляції півколових каналів і світлової стимуляції (відкриття очей). Виявлено залежність між амплітудою і частотою мозкових ритмів у стані відносного фізіологічного спокою та при подразненні вестибулярних і зорових рецепторівДля оцінки динаміки електричної активності головного мозку проводився запис ЕЕГ у фоновому режимі (при закритих очах обстежуваних) і при пред'явленні аферентних подразників у виді стимуляції півколових каналів і світлової стимуляції (відкриття очей). Виявлено залежність між амплітудою і частотою мозкових ритмів у стані відносного фізіологічного спокою та при подразненні вестибулярних і зорових рецепторі

The methodology of calculation of sample size in “non-inferiority” comparative controlled clinical trials: a comparison of two proportions in parallel group

The absolute majority of clinical trials of generic drugs aimed to compare the therapeutic efficacy of the tested drug and the drug of an active control. It is necessary to estimate that the test drug is not less effective (or non-inferior) than the control drug. The designs of the aforementioned trials are called “non-inferiority” study; often, these are phase III of clinical trials. The primary criterions of effectiveness which are quite often used in the clinical trials are frequencies of signs, as a result of the analysis of binary data. Binary data are analyzed by comparing proportions. One of the most important conditions for a correct interpretation of the data obtained during the clinical trials — to provide necessary and suffi cient sample size. The purpose of this article is to show how to plan the study, how to provide necessary and sufficient sample size to ensure that the results and conclusions would be reliable; how to interpret the data in a comparative controlled study aimed to establish “non­inferiority” using proportions comparing in parallel groups

Analysis of a robust edge detection system in different color spaces using color and depth images

Edge detection is very important technique to reveal significant areas in the digital image, which could aids the feature extraction techniques. In fact it is possible to remove un-necessary parts from image, using edge detection. A lot of edge detection techniques has been made already, but we propose a robust evolutionary based system to extract the vital parts of the image. System is based on a lot of pre and post-processing techniques such as filters and morphological operations, and applying modified Ant Colony Optimization edge detection method to the image. The main goal is to test the system on different color spaces, and calculate the system’s performance. Another novel aspect of the research is using depth images along with color ones, which depth data is acquired by Kinect V.2 in validation part, to understand edge detection concept better in depth data. System is going to be tested with 10 benchmark test images for color and 5 images for depth format, and validate using 7 Image Quality Assessment factors such as Peak Signal-to-Noise Ratio, Mean Squared Error, Structural Similarity and more (mostly related to edges) for prove, in different color spaces and compared with other famous edge detection methods in same condition. Also for evaluating the robustness of the system, some types of noises such as Gaussian, Salt and pepper, Poisson and Speckle are added to images, to shows proposed system power in any condition. The goal is reaching to best edges possible and to do this, more computation is needed, which increases run time computation just a bit more. But with today’s systems this time is decreased to minimum, which is worth it to make such a system. Acquired results are so promising and satisfactory in compare with other methods available in validation section of the paper