1,749 research outputs found
Cavitation of Electrons Bubbles in Liquid Helium Below saturation Pressure
We have used a Hartree-type electron-helium potential together with a density
functional description of liquid He and He to study the explosion of
electron bubbles submitted to a negative pressure. The critical pressure at
which bubbles explode has been determined as a function of temperature. It has
been found that this critical pressure is very close to the pressure at which
liquid helium becomes globally unstable in the presence of electrons. It is
shown that at high temperatures the capillary model overestimates the critical
pressures. We have checked that a commonly used and rather simple
electron-helium interaction yields results very similar to those obtained using
the more accurate Hartree-type interaction. We have estimated that the
crossover temperature for thermal to quantum nucleation of electron bubbles is
very low, of the order of 6 mK for He.Comment: 22 pages, 9 figure
The effect of pressure on statics, dynamics and stability of multielectron bubbles
The effect of pressure and negative pressure on the modes of oscillation of a
multi-electron bubble in liquid helium is calculated. Already at low pressures
of the order of 10-100 mbar, these effects are found to significantly modify
the frequencies of oscillation of the bubble. Stabilization of the bubble is
shown to occur in the presence of a small negative pressure, which expands the
bubble radius. Above a threshold negative pressure, the bubble is unstable.Comment: 4 pages, 2 figures, accepted for publication in Physical Review
Letter
The accident insurance as a promising direction for insurance in Russia
Статья посвящена анализу состояния рынка услуг страхования от несчастных случаев. Актуальность исследования определяется тем, что страхование является неотъемлемым атрибутом цивилизованного общества, позволяющим сохранить обеспеченность доходами при неблагоприятных ситуациях. По статистике в России уровень травматизма и непредвиденных обстоятельств весьма велик. Люди традиционно уделяют мало внимания формированию резервов на случай временной или постоянной нетрудоспособности. Цель работы: рассмотреть систему страхования от несчастных случаев. Методы исследования: метод сопоставления, необходимый для выявления главных тенденций на рынке страховых услуг; аналитический метод, позволяющий понять, какие проблемы характерны для этого вида страхования; статистический метод, выявляющий масштабы страхования от несчастных случаев. Результаты: раскрывается сущность и виды страхования от несчастных случаев.The article is devoted to analysis of service market of accident insurance. The relevant of the study is determined by the fact that insurance is an integral attribute of a civilized society that allows you to save security income in adverse situations. According to statistics, in Russia the level of injury and unforeseen circumstances is very great. People traditionally pay little attention to formation of reserves in case of temporary or permanent incapacity for work. The main aim of the study is to consider the system of the accident insurance. Methods: the matching method required to identify the main trends in the insurance market; the analytical technique which allows understanding the typical problems for this type of insurance; the statistical method allows us to identify the extent of accident insurance. Results. The paper reveals the essence and types of accident insurance and considers the model events when the insurance company indemnifies for the damage. The causes of the demand for this type of insurance in Russia are identified. Based on the statistical data the author has determined the proportion of the accident insured people
Path integral Monte Carlo simulation of helium at negative pressures
Path integral Monte Carlo (PIMC) simulations of liquid helium at negative
pressure have been carried out for a temperature range from the critical
temperature to below the superfluid transition. We have calculated the
temperature dependence of the spinodal line as well as the pressure dependence
of the isothermal sound velocity in the region of the spinodal. We discuss the
slope of the superfluid transition line and the shape of the dispersion curve
at negative pressures.Comment: 6 pages, 7 figures, submitted to Physical Review B Revised: new
reference, replaced figure
Templated growth of metal-organic coordination chains at surfaces
Line them up: Metal\u2013organic chains (see scanning tunneling microscopy image) have been created in situ by self\u2010organized growth at a metal surface under ultrahigh vacuum. These 1D arrangements of metal centers (Fe, Cu), regularly spaced by organic linkers such as trimesitylic acid, open new possibilities for the study of low\u2010dimensional magnetism
More Scalable LTL Model Checking via Discovering Design-Space Dependencies (D3)
Modern system design often requires comparing several models over a large design space. Different models arise out of a need to weigh different design choices, to check core capabilities of versions with varying features, or to analyze a future version against previous ones. Model checking can compare different models; however, applying model checking off-the-shelf may not scale due to the large size of the design space for today’s complex systems. We exploit relationships between different models of the same (or related) systems to optimize the model-checking search. Our algorithm, D3 , preprocesses the design space and checks fewer model-checking instances, e.g., using nuXmv. It automatically prunes the search space by reducing both the number of models to check, and the number of LTL properties that need to be checked for each model in order to provide the complete model-checking verdict for every individual model-property pair. We formalize heuristics that improve the performance of D3 . We demonstrate the scalability of D3 by extensive experimental evaluation, e.g., by checking 1,620 real-life models for NASA’s NextGen air traffic control system. Compared to checking each model-property pair individually, D3 is up to 9.4 × faster
From a certain point of view: sensory phenomenological envisionings of running space and place
The precise ways in which we go about the mundane, repetitive, social actions of everyday life are central concerns of ethnographers and theorists working within the traditions of the sociology of the mundane and sociological phenomenology. In this article, we utilize insights derived from sociological phenomenology and the newly developing field of sensory sociology to investigate a particular, mundane, and embodied social practice, that of training for distance running in specific places: our favored running routes. For, despite a growing body of ethnographic studies of particular sports, little analytic attention has been devoted to the actual, concrete practices of “doing” or “producing” sporting activity, particularly from a sensory ethnographic perspective. Drawing upon data from a 2-year joint autoethnographic research project, here we explore the visual dimension, focusing upon three key themes in relation to our runners’ visualization of, respectively, (1) hazardous places, (2) performance places, (3) the time–space–place nexus
Status of the LUX Dark Matter Search
The Large Underground Xenon (LUX) dark matter search experiment is currently
being deployed at the Homestake Laboratory in South Dakota. We will highlight
the main elements of design which make the experiment a very strong competitor
in the field of direct detection, as well as an easily scalable concept. We
will also present its potential reach for supersymmetric dark matter detection,
within various timeframes ranging from 1 year to 5 years or more.Comment: 4 pages, in proceedings of the SUSY09 conferenc
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