Mesoscopic and microscopic dipole clusters: Structure and phase transitions

Two dimensional (2D) classical system of dipole particles confined by a quadratic potential is studied. For clusters of N < 81 particles ground state configurations and appropriate eigenfrequencies and eigenvectors for the normal modes are found. Monte Carlo and molecular dynamic methods are used to study in detail the order - disorder transition (the "melting" of clusters). In mesoscopic clusters (N < 37) there is a hierarchy of transitions: at lower temperatures an intershell orientational disordering of pairs of shells takes place; at higher temperatures the intershell diffusion sets in and the shell structure disappears. In "macroscopic" clusters (N > 37) an orientational "melting" of only the outer shell is possible. The most stable clusters (having both maximal lowest nonzero eigenfrequencies and maximal temperatures of total melting) are that of completed crystal shells which are concentric groups of nodes of 2D hexagonal lattice with a number of nodes placed in the center of them. The study of different quantities shows that the melting temperature is a nonmonotonic function of the number of particles in the system. The dynamical equilibrium between "solidlike" and "orientationally disordered" forms of clusters is considered.Comment: 12 pages, 16 Postscript figures. Submitted to Phys. Rev.

Phase diagram of 2D array of mesoscopic granules

A lattice boson model is used to study ordering phenomena in regular 2D array of superconductive mesoscopic granules, Josephson junctions or pores filled with a superfluid helium. Phase diagram of the system, when quantum fluctuations of both the phase and local superfluid density are essential, is analyzed both analytically and by quantum Monte Carlo technique. For the system of strongly interacting bosons it is found that as the boson density $n_0$ is increased the boundary of ordered superconducting state shifts to {\it lower temperatures} and at $n_0 > 8$ approaches its limiting position corresponding to negligible relative fluctuations of moduli of the order parameter (as in an array of "macroscopic" granules). In the region of weak quantum fluctuations of phases mesoscopic phenomena manifest themselves up to $n_0 \sim 10$. The mean field theory and functional integral $1/n_0$ - expansion results are shown to agree with that of quantum Monte Carlo calculations of the boson Hubbard model and its quasiclassical limit, the quantum XY model.Comment: 7 pages, 5 Postscript figure

Quantum orientational melting of mesoscopic clusters

By path integral Monte Carlo simulations we study the phase diagram of two - dimensional mesoscopic clusters formed by electrons in a semiconductor quantum dot or by indirect magnetoexcitons in double quantum dots. At zero (or sufficiently small) temperature, as quantum fluctuations of particles increase, two types of quantum disordering phenomena take place: first, at small values of quantum de Boer parameter q < 0.01 one can observe a transition from a completely ordered state to that in which different shells of the cluster, being internally ordered, are orientationally disordered relative to each other. At much greater strengths of quantum fluctuations, at q=0.1, the transition to a disordered (superfluid for the boson system) state takes place.Comment: 4 pages, 6 Postscript figure

Pharmacoeconomic analysis of the etravirine compared to raltegravir in treatment HIV-infected adult patients, previously treated with antiretroviral drugs

Objective: To perform comprehensive pharmacoeconomical assessment of use etravirine and raltegravir in HIV-infected patients. Methodology: Cost-eifectiveness and budget impact analyses of etravirine or raltegravir on the top of optimized background therapy in adult treatment-experienced HIV-infected patients were conducted. Results: Cost to achieve an undetectable viral load

New model for system of mesoscopic Josephson contacts

Quantum fluctuations of the phases of the order parameter in 2D arrays of mesoscopic Josephson junctions and their effect on the destruction of superconductivity in the system are investigated by means of a quantum-cosine model that is free of the incorrect application of the phase operator. The proposed model employs trigonometric phase operators and makes it possible to study arrays of small superconducting granules, pores filled with superfluid helium, or Josephson junctions in which the average number of particles $n_0$ (effective bosons, He atoms, and so on) is small, and the standard approach employing the phase operator and the particle number operator as conjugate ones is inapplicable. There is a large difference in the phase diagrams between arrays of macroscopic and mesoscopic objects for $n_0 < 5$ and $U<J$ ($U$ is the characteristic interaction energy of the particle per granule and $J$ is the Josephson coupling constant). Reentrant superconductivity phenomena are discussed.Comment: 4 pages, 3 Postscript figure

Josephson array of mesoscopic objects. Modulation of system properties through the chemical potential

The phase diagram of a two-dimensional Josephson array of mesoscopic objects is examined. Quantum fluctuations in both the modulus and phase of the superconducting order parameter are taken into account within a lattice boson Hubbard model. Modulating the average occupation number $n_0$ of the sites in the system leads to changes in the state of the array, and the character of these changes depends significantly on the region of the phase diagram being examined. In the region where there are large quantum fluctuations in the phase of the superconducting order parameter, variation of the chemical potential causes oscillations with alternating superconducting (superfluid) and normal states of the array. On the other hand, in the region where the bosons interact weakly, the properties of the system depend monotonically on $n_0$. Lowering the temperature and increasing the particle interaction force lead to a reduction in the width of the region of variation in $n_0$ within which the system properties depend weakly on the average occupation number. The phase diagram of the array is obtained by mapping this quantum system onto a classical two-dimensional XY model with a renormalized Josephson coupling constant and is consistent with our quantum Path-Integral Monte Carlo calculations.Comment: 12 pages, 8 Postscript figure

Pharmacoeconomic aspects of the diabetic ketoacidosis prevention in type 1 diabetes mellitus by self-monitoring of blood ketones

Diabetic ketoacidosis (DKA) is one of the most serious acute complications observed with a frequency of 10-100 cases per year per 1000 patients with type 1 diabetes mellitus (DM1). More than a third of patients with DKA are admitted to hospital in diabetic coma state (DC) with mortality of 19%. In spite of the serious complications and the high social importance, the problem of preventing the DKA has received little attention. Objective: To evaluate the epidemiology of the DKA and pharmacoeconomic aspects of monitoring blood ketones at home, as one of the measures of prevention of diabetic ketoacidosis in patients with type 1 diabetes in Russia. Materials and methods. A literature search was conducted among national and international databases. Direct medical costs for treatment of the DKA and DC were studied in several hospitals of the Russian Federation. Cost-eff ectiveness of preventing the DKA for the public health system was evaluated. Results. Over 2.05 thousands of children’s and adolescents, and 14.9 thousand of adults with DM1 and the DKA are hospitalized annually in the Russian Federation, 0.62 and 7.47 thousands respectively in a state of DC that leads to a total cost of hospitalization of 63.8 millions, and 528.6 millions rubles, respectively. Monitoring of ketone bodies at home is one of the main methods for the prevention of DKA. Two methods for detecting ketosis are currently available in the Russian Federation: blood β-hydroxybutyrate testing and urine acetoacetate testing. Measurement of β-ketones in the blood as an accurate indicator of the amount of ketones in the microcirculation, shows the level of ketones in the blood at the present moment, allows adjust therapy and almost twice reduces the need for hospitalization, that may lead to a reduction in the annual cost of treatment of DKA and DC in hospitals by almost 300 million rubles in Russia. Conclusions. Th e widespread introduction of measuring β-ketones in the blood in routine practice for patients with DM1 will greatly reduce the number of hospitalizations and deaths due to diabetic ketoacidosis, as well as healthcare costs associated with this condition

Comparative clinical and economic analysis Jodantipyrin for emergency prevention of tick-borne encephalitis

Objective: To conduct a comparative pharmacoeconomic analysis Jodantipyrin drugs and Human immunoglobulin against tick-borne encephalitis (TBE) for emergency prevention of tick-borne encephalitis in a health care system of the Russian Federation. Methodology: The study is an analysis of costs, cost-effectiveness and budget impact and consists of a single line of therapy. Results: Cost analysis shows that in the case of the health budget Jodantipyrin costs associated with treatment of established TBE 2.2 times lower than that of the Immunoglobulin against tick-borne encephalitis, and the costs of the use of means of emergency prevention Jodantipyrin - at 11,3 times less

A New High Energy Photon Tagger for the H1 - Detector at HERA

The H1 detector at HERA has been upgraded by the addition of a new electromagnetic calorimeter. This is installed in the HERA tunnel close to the electron beam line at a position 8m from the interaction point in the electron beam direction. The new calorimeter extends the acceptance for tagged photoproduction events to the high y range, 0.85 < y < 0.95, and thus significantly improves the capability of H1 to study high energy gamma-p processes. The calorimeter design, performance and first results obtained during the 1996-1999 HERA running are described.Comment: 17 pages, 16 figure