Possible influence of the two string events on the hadron formation in a nuclear environment

One of the basic assumptions of the string model is that as a result of a DIS in nucleus a single string arises, which then breaks into hadrons. However the pomeron exchange considered in this work, leads to the production of two strings in the one event. The hadrons produced in these events have smaller formation lengths, than those with the same energy produced in the single string events. As a consequence, they undergo more substantial absorption in the nuclear matter

Nuclear Attenuation of high energy two-hadron system in the string model

Nuclear attenuation of the two-hadron system is considered in the string model. The two-scale model and its improved version with two different choices of constituent formation time and sets of parameters obtained earlier for the single hadron attenuation, are used to describe available experimental data for the $z$-dependence of subleading hadron, whereas satisfactory agreement with the experimental data has been observed. A model prediction for $\nu$-dependence of the nuclear attenuation of the two-hadron system is also presented.Comment: 8 page

A study of the double hadron neutrinoproduction on nuclei

The nuclear medium influence on the dihadron neutrinoproduction is investigated for the first time, using the data obtained with SKAT bubble chamber. An indication is obtained that the nuclear attenuation of the dihadron is more expressed for kinematically closest hadron pairs. The experimental data on the dihadron attenuation and on the ratio of the dihadron to single-hadron yields are compared with predictions of the two-scale string fragmentation model.Comment: 5 pages, 10 figure

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

Optimal Investment in the Development of Oil and Gas Field

Let an oil and gas field consists of clusters in each of which an investor can launch at most one project. During the implementation of a particular project, all characteristics are known, including annual production volumes, necessary investment volumes, and profit. The total amount of investments that the investor spends on developing the field during the entire planning period we know. It is required to determine which projects to implement in each cluster so that, within the total amount of investments, the profit for the entire planning period is maximum. The problem under consideration is NP-hard. However, it is solved by dynamic programming with pseudopolynomial time complexity. Nevertheless, in practice, there are additional constraints that do not allow solving the problem with acceptable accuracy at a reasonable time. Such restrictions, in particular, are annual production volumes. In this paper, we considered only the upper constraints that are dictated by the pipeline capacity. For the investment optimization problem with such additional restrictions, we obtain qualitative results, propose an approximate algorithm, and investigate its properties. Based on the results of a numerical experiment, we conclude that the developed algorithm builds a solution close (in terms of the objective function) to the optimal one

Performance of the Electromagnetic Calorimeter of the HERMES Experiment

The performance of the electromagnetic calorimeter of the HERMES experiment is described. The calorimeter consists of 840 radiation resistant F101 lead-glass counters. The response to positrons up to 27.5 GeV, the comparison between the measured energy and the momentum reconstructed from tracking, long-term stability, hadron rejection and neutral meson invariant mass reconstruction are shown.Comment: 22 pages, 13 figures, LaTeX, accepted by NI

АЛЬТЕРНАТИВНЫЙ МЕТОД ХИРУРГИЧЕСКОЙ КОРРЕКЦИИ РАССЛАИВАЮЩИХ АНЕВРИЗМ АОРТЫ В СОЧЕТАНИИ С АОРТАЛЬНОЙ НЕДОСТАТОЧНОСТЬЮ

Patients with dissecting aortic aneurysm and associated acute aortic insufficiency form a group of seriously ill patients with significant cardiac failure, generally involving other organs and systems. It justifies an attempt to reduce a surgical risk, by using more sparing procedures, including supracoronary replacement of the ascending aorta with its root reconstruction. The latter has been performed in 27 patients (mean 54,5 ± 2,1 years) with dissecting aortic aneurysm and aortic valvular insufficiency in 1996 to 2009. The major etiological factor was atherosclerosis (88%)/ Seventeen (63%), 6 (22,2%) and 4 (16%) had types I, IIA and II dissection, respectively. Overall hospital mortality was 11%. In late period, progressive aneurysm dissection needed reinterventions in 2 cases. The competence of the reconstructed aortic valve was satisfactory both just after surgery and throughout the follow-up. Indications for this option of chronic correction, surgical techniques, and immediate and long-term results are outlined. Пациенты с расслаивающей аневризмой аорты с сопутствующей аортальной недостаточностью состав- ляют группу тяжелых больных с выраженной сердечной недостаточностью и, как правило, заинтересо- ванностью других органов и систем. В связи с этим оправданным является стремление снизить риск опе- рации благодаря использованию более щадящих методик, в частности супракоронарного протезирования восходящей аорты с реконструкцией ее корня. Такого типа операции в ФНЦТиИО выполняют с 1996 года. За период с 1996-го по 2009 год 27 пациентам с расслаивающей аневризмой аорты и недостаточностью аортального клапана, средний возраст которых составил 54,5 ± 2,1 года, было выполнено супракоро- нарное протезирование аорты. Основным этиологическим фактором был атеросклероз – 89%. 17 (63%) пациентов имели I тип, 6 (22,2%) – IIA тип и 4 (14,8%) – II тип расслоения. Помимо супракоронарного протезирования аорты в 4 случаях потребовалось полное протезирование дуги аорты, в 13 – частичное. Общая госпитальная летальность составила 11%.

Beam-helicity asymmetries for single-hadron production in semi-inclusive deep-inelastic scattering from unpolarized hydrogen and deuterium targets

A measurement of beam-helicity asymmetries for single-hadron production in deep-inelastic scattering is presented. Data from the scattering of 27.6 GeV electrons and positrons off gaseous hydrogen and deuterium targets were collected by the HERMES experiment. The asymmetries are presented separately as a function of the Bjorken scaling variable, the hadron transverse momentum, and the fractional energy for charged pions and kaons as well as for protons and anti-protons. These asymmetries are also presented as a function of the three aforementioned kinematic variables simultaneously