Use of levosimendan in acute heart failure

Peer reviewe

Moving Atom-Field Interactions: Quantum Motional Decoherence and Relaxation

The reduced dynamics of an atomic qubit coupled both to its own quantized center of mass motion through the spatial mode functions of the electromagnetic field, as well as the vacuum modes, is calculated in the influence functional formalism. The formalism chosen can describe the entangled non-Markovian evolution of the system with a full account of the coherent back-action of the environment on the qubit. We find a slight increase in the decoherence due to the quantized center of mass motion and give a condition on the mass and qubit resonant frequency for which the effect is important. In optically resonant alkali-metal atom systems, we find the effect to be negligibly small. The framework presented here can nevertheless be used for general considerations of the coherent evolution of qubits in moving atoms in an electromagnetic field.Comment: 9 pages, 1 figure, minor change

A generalized bag-like boundary condition for fields with arbitrary spin

Boundary conditions (BCs) for the Maxwell and Dirac fields at material surfaces are widely-used and physically well-motivated, but do not appear to have been generalized to deal with higher spin fields. As a result there is no clear prescription as to which BCs should be selected in order to obtain physically-relevant results pertaining to confined higher spin fields. This lack of understanding is significant given that boundary-dependent phenomena are ubiquitous across physics, a prominent example being the Casimir effect. Here, we use the two-spinor calculus formalism to present a unified treatment of BCs routinely employed in the treatment of spin-1/2 and spin-1 fields. We then use this unification to obtain a BC that can be applied to massless fields of any spin, including the spin-2 graviton, and its supersymmetric partner the spin-3/2 gravitino

Resumming the large-N approximation for time evolving quantum systems

In this paper we discuss two methods of resumming the leading and next to leading order in 1/N diagrams for the quartic O(N) model. These two approaches have the property that they preserve both boundedness and positivity for expectation values of operators in our numerical simulations. These approximations can be understood either in terms of a truncation to the infinitely coupled Schwinger-Dyson hierarchy of equations, or by choosing a particular two-particle irreducible vacuum energy graph in the effective action of the Cornwall-Jackiw-Tomboulis formalism. We confine our discussion to the case of quantum mechanics where the Lagrangian is $L(x,\dot{x}) = (1/2) \sum_{i=1}^{N} \dot{x}_i^2 - (g/8N) [ \sum_{i=1}^{N} x_i^2 - r_0^2 ]^{2}$. The key to these approximations is to treat both the $x$ propagator and the $x^2$ propagator on similar footing which leads to a theory whose graphs have the same topology as QED with the $x^2$ propagator playing the role of the photon. The bare vertex approximation is obtained by replacing the exact vertex function by the bare one in the exact Schwinger-Dyson equations for the one and two point functions. The second approximation, which we call the dynamic Debye screening approximation, makes the further approximation of replacing the exact $x^2$ propagator by its value at leading order in the 1/N expansion. These two approximations are compared with exact numerical simulations for the quantum roll problem. The bare vertex approximation captures the physics at large and modest $N$ better than the dynamic Debye screening approximation.Comment: 30 pages, 12 figures. The color version of a few figures are separately liste

The Taming of Closed Time-like Curves

We consider a $R^{1,d}/Z_2$ orbifold, where $Z_2$ acts by time and space reversal, also known as the embedding space of the elliptic de Sitter space. The background has two potentially dangerous problems: time-nonorientability and the existence of closed time-like curves. We first show that closed causal curves disappear after a proper definition of the time function. We then consider the one-loop vacuum expectation value of the stress tensor. A naive QFT analysis yields a divergent result. We then analyze the stress tensor in bosonic string theory, and find the same result as if the target space would be just the Minkowski space $R^{1,d}$, suggesting a zero result for the superstring. This leads us to propose a proper reformulation of QFT, and recalculate the stress tensor. We find almost the same result as in Minkowski space, except for a potential divergence at the initial time slice of the orbifold, analogous to a spacelike Big Bang singularity. Finally, we argue that it is possible to define local S-matrices, even if the spacetime is globally time-nonorientable.Comment: 37 pages, LaTeX2e, uses amssymb, amsmath and epsf macros, 8 eps and 3 ps figures; (v2): Two additional comments + one reference added; (v3): corrections in discussion of CTCs + some clarification

Анализ технологий по предупреждению формирования газовых гидратов на Заполярном нефтегазоконденсатном месторождении (ЯНАО)

Объектами исследования являются осложнения, возникающие при гидратоотложении в системах сбора и транспортировки газа. Предметом исследования являются комплексные методы предупреждения образования гидратов природного газа. Цель выпускной квалификационной работы – анализ методов и технологий защиты промыслового оборудования от осложнений, вызванных гидратообразованием.The objects of the following research are the problems appearing from the hydrate formation in gas gathering facilities and transportation systems. The subjects of the research are complex methods of preventing the formation of natural gas hydrates. The purpose of the graduation thesis is to analyze methods and technologies for protecting field equipment from problems caused by hydrate formation

Semiclassical Mechanics of the Wigner 6j-Symbol

The semiclassical mechanics of the Wigner 6j-symbol is examined from the standpoint of WKB theory for multidimensional, integrable systems, to explore the geometrical issues surrounding the Ponzano-Regge formula. The relations among the methods of Roberts and others for deriving the Ponzano-Regge formula are discussed, and a new approach, based on the recoupling of four angular momenta, is presented. A generalization of the Yutsis-type of spin network is developed for this purpose. Special attention is devoted to symplectic reduction, the reduced phase space of the 6j-symbol (the 2-sphere of Kapovich and Millson), and the reduction of Poisson bracket expressions for semiclassical amplitudes. General principles for the semiclassical study of arbitrary spin networks are laid down; some of these were used in our recent derivation of the asymptotic formula for the Wigner 9j-symbol.Comment: 64 pages, 50 figure

Программное обеспечение для определения, построения и визуализации двухмерной и трехмерной графики

Работа направлена на создание библиотеки для работы с двухмерной и трехмернйой графикой и программного обеспечения, которое будет использовать данную библиотеку для трехмерной и двухмерной визуализации структуры проектов организации.The work is aimed at creating the software library for working with two-dimensional and three-dimensional graphics and software that will use this library for three-dimensional and two-dimensional visualization of the structure of the organization's projects

Численное моделирование влияния радиационного теплопереноса в микросферах тонкопленочных теплоизоляционных покрытий на тепловые потери теплопроводов

Объектом исследования является нанесенный на трубопровод слой сверхтонкой теплоизоляции толщиной 0,33 мм, предполагалось что слой состоит из связующего вещества заполненного микросферами с соотношением 38:62. Моделирование проводилось для микросфер с двумя значениями толщины стенки. Цель работы – моделирование влияния радиационного теплопереноса в микросферах тонкопленочных теплоизоляционных покрытий на тепловые потери теплопроводов. В ходе исследования с помощью функций и средств, имеющихся в пакете программ мультифизического моделирования COMSOL Multiphisics, было проведено моделирование тепловых режимов слоя изоляции.The object of the study is a layer of ultra-thin thermal insulation applied to the pipeline with a thickness of 0.33 mm. it was assumed that the layer consists of a binder filled with microspheres with a ratio of 38:62. The simulation was performed for microspheres with two values of wall thickness. The aim of this work is to model the effect of radiation heat transfer in microspheres of thin-film thermal insulation coatings on heat losses of heat pipelines. In the course of the study, the thermal modes of the insulation layer were simulated using the functions and tools available in the COMSOL Multiphisics multiphysics software package