Analysis and calibration of absorptive images of Bose-Einstein condensate at non-zero temperatures

We describe the method allowing quantitative interpretation of absorptive images of mixtures of BEC and thermal atoms which reduces possible systematic errors associated with evaluation of the contribution of each fraction. By using known temperature dependence of the BEC fraction, the analysis allows precise calibration of the fitting results. The developed method is verified in two different measurements and compares well with theoretical calculations and with measurements performed by another group.Comment: 17 pages, 8 figure

Current challenges in de novo plant genome sequencing and assembly

ABSTRACT: Genome sequencing is now affordable, but assembling plant genomes de novo remains challenging. We assess the state of the art of assembly and review the best practices for the community

Mechanical Behavior and Failure of Riveting Joints in Tensile and Shear Tests

Основным критерием прочности заклепочных соединений при их разработке является сопротивление материала заклепок сдвиговому нагружению. При испытании на сдвиг обычных заклепочных соединений определяющими являются механические характеристики материала заклепки. Поэтому необходимо описание механизма разрушения различных соединений при испытаниях на растяжение. Оценивается прочность разных листовых материалов (сталь DC01, алюминиевый сплав AW-5754 и их комбинация) в заклепочном соединении. Анализируется механизм разрушения заклепочных соединений при одноосном растяжении Т-образных образцов из различных листовых материалов. Выполнено сравнение экспериментальных результатов, полученных при растяжении и сдвиге заклепочных соединений внахлестку для одного и того же типа.Основним критерієм міцності заклепочних з’єднань при їх розробці є опір матеріалу заклепок зсувному навантаженню. При випробуваннях на зсув звичайних заклепочних з’єднань визначальними є механічні характеристики матеріалу заклепки. У зв’язку з цим необхідно описання механізму руйнування різних з’єднань при випробуваннях на розтяг. Оцінюється міцність різних листових матеріалів (сталь DC01, алюмінієвий сплав AW-5754 та їх комбінація) у заклепочних з’єднаннях. Аналізується механізм руйнування заклепочних з’єднань при одновісному розтязі Т-подібних зразків із різних листових матеріалів. Виконано порівняння експериментальних результатів, отриманих при розтязі і стиску заклепочних з’єднать внапуск для одного і того ж типу

FEM Analysis of Stress Distribution in the Hermetic Harmonic Drive Flexspline

The paper deals with the numerical stress calculation in the flexspline tooth rim of the harmonic drive. Due to the complex geometry of the toothed ring in the flexspline, the teeth were modeled as a ring, which height corresponded to the particular stress concentration in the teeth. To study the effect of type of wave generator on the stress distribution in the flexspline, the following models were elaborated: two-roller, four-roller, cam, and disk. The stress calculations were performed for the two cases: a zero torque load and the torque load value, corresponding to the true operation conditions of the hermetic harmonic drivВиконано чисельний розрахунок напружень у гнучкому сплайні зубчатої передачі гармонічного (хвильового) редуктора. Зубчате кільце у гнучкому сплайні через складну геометрію моделювалось у вигляді кільця. Висоту кільця приймали з урахуванням напруженості в зубцях. Для вивчення впливу різних типів хвильових генераторів на розподіл напружень у гнучкому сплайні розглядали моделі з двома та чотирма роликами, ексцентриком або диском. Розрахунок напружень виконували для двох варіантів: без обертального моменту та з обертальним моментом, що відповідає реальним умовам роботи герметичного гармонічного редуктора.Проведен численный расчет напряжений в гибком сплайне зубчатой передачи гармонического (волнового) редуктора. Зубчатое кольцо в гибком сплайне из-за сложной геометрии моделировалось в виде кольца. Высоту кольца принимали с учетом напряженности в зубьях. Для изучения влияния различных типов волновых генераторов на распределение напряжений в гибком сплайне рассматривали модели с двумя и четырьмя роликами, эксцентриком и диском. Расчет напряжений выполняли для двух вариантов: без вращающего момента и с вращающим моментом, соответствующим реальным условиям работы герметического гармонического редуктора

Field Worker Exposure to Selected Insecticides Applied to Com Via Center-Pivot Irrigation

Field workerswere monitored for dermal and respiratory exposure to chlorpyrifos (with and without crop oil), carbaryl, and permethrin at reentry intervals of 2, 4, 8, 24, and 48 h after application. Insecticides were applied to R3 stage corn through an overhead center-pivot irrigation system. Dermal exposure was measured by analyzing 18 gauze pads attached to the clothing of workers to represent human body regions. Hand exposure was determined using cotton gloves. Respiratory exposure was determined using portable air samplers equipped with polyurethane foam plugs to trap ambient insecticide residues. Gas liquid chromatography was used to quantify residues of chlorpyrifos and permethrin in gauze pads, gloves, and foam plugs. Carbaryl residues in pads, gloves, and foam plugs were analyzed using high-performance liquid chromatography. Highest dermal and respiratory exposures were found at the 2-h reentry interval. Exposures decreased as reentry interval increased. Dermal exposure was primarily confined to the hands. Residues detected by air samplers ranged from 0 to 0.03 μg/liter. Based on the estimated percentages of acute toxic dose (all \u3c0.00038%), the risk of acute toxicity to workers at the intervals studied was low

Parachute Models Used in the Mars Science Laboratory Entry, Descent, and Landing Simulation

An end-to-end simulation of the Mars Science Laboratory (MSL) entry, descent, and landing (EDL) sequence was created at the NASA Langley Research Center using the Program to Optimize Simulated Trajectories II (POST2). This simulation is capable of providing numerous MSL system and flight software responses, including Monte Carlo-derived statistics of these responses. The MSL POST2 simulation includes models of EDL system elements, including those related to the parachute system. Among these there are models for the parachute geometry, mass properties, deployment, inflation, opening force, area oscillations, aerodynamic coefficients, apparent mass, interaction with the main landing engines, and off-loading. These models were kept as simple as possible, considering the overall objectives of the simulation. The main purpose of this paper is to describe these parachute system models to the extent necessary to understand how they work and some of their limitations. A list of lessons learned during the development of the models and simulation is provided. Future improvements to the parachute system models are proposed

Thermal transformations of Cu–Mg (Zn)–Al(Fe) hydrotalcite-like materials into metal oxide systems and their catalytic activity in selective oxidation of ammonia to dinitrogen

Layered double hydroxides (LDHs) containing Mg^{2+}, Cu^{2+} or Zn^{2+} cations in the Me^{II} positions and Al^{3+} and Fe^{3+} in the Me^{III} positions were synthesized by co- precipitation method. Detailed studies of thermal trans- formation of obtained LDHs into metal oxide systems were performed using high temperature X-ray diffraction in oxidising and reducing atmosphere, thermogravimetry coupled with mass spectrometry and temperature-pro- grammed reduction. The LDH samples calcined at 600 and 900 °C were tested in the role of catalysts for selective oxidation of ammonia into nitrogen and water vapour. It was shown that all copper congaing samples presented high catalytic activity and additionally, for the Cu–Mg–Al and Cu–Mg–Fe hydrotalcite samples calcined at 600 °C rela- tively high stability and selectivity to dinitrogen was obtained. An increase in calcination temperature to 900 °C resulted in a decrease of their catalytic activity, possibly due to formation of well-crystallised metal oxide phase which are less catalytically active in the process of selective oxidation of ammonia

BaWO4:Ce Single Crystals Codoped with Na Ions

Single crystals of BaWO4, BaWO4:0.5at.%Ce; BaWO4:1at.%Ce; BaWO4:0.5at.%Ce,1at.%Na; and BaWO4:1at.%Ce,2at.%Na were grown from an inductively heated iridium crucible by the Czochralski method on a Malvern MSR4 puller. They were investigated using Electron Paramagnetic Resonance (EPR) spectroscopy at helium temperatures. One isolated center of high (D2d or S4) symmetry was found and two or more other centers of lower symmetry were identified, depending on crystal doping. From the fitting using the EPR-NMR program, the following parameters of g-matrix for the high symmetry center were found: gx = 1.505, gy = 1.505, and gz = 2.731. The linewidth vs. temperature revealed an increasing exponential tendency with increasing temperature. It showed one phonon at the lower temperatures and a Raman + Orbach effect at the higher temperatures. Radioluminescence and pulse height spectra showed rather poor scintillation properties, without any contribution from cerium emission