The Standard Quantum Limit of Coherent Beam Combining

Coherent beam combining refers to the process of generating a bright output beam by merging independent input beams with locked relative phases. We report the first quantum mechanical noise limit calculations for coherent beam combining and compare our results to quantum-limited amplification. Our coherent beam combining scheme is based on an optical Fourier transformation which renders the scheme compatible with integrated optics. The scheme can be layed out for an arbitrary number of input beams and approaches the shot noise limit for a large number of inputs

Non-existence of normal tokamak equilibria with negative central current

Recent tokamak experiments employing off-axis, non-inductive current drive have found that a large central current hole can be produced. The current density is measured to be approximately zero in this region, though in principle there was sufficient current drive power for the central current density to have gone significantly negative. Recent papers have used a large aspect-ratio expansion to show that normal MHD equilibria (with axisymmetric nested flux surfaces, non-singular fields, and monotonic peaked pressure profiles) can not exist with negative central current. We extend that proof here to arbitrary aspect ratio, using a variant of the virial theorem to derive a relatively simple integral constraint on the equilibrium. However, this constraint does not, by itself, exclude equilibria with non-nested flux surfaces, or equilibria with singular fields and/or hollow pressure profiles that may be spontaneously generated.Comment: 5 pages, 3 figures. Submitted to Physics of Plasmas, Feb. 14, 2003. Revised Feb. 24, 2003. Vers. 2: revised May 29 to clarify points raised by referee, add references to recent work. July 18, accepted for publicatio

Premartensitic transition driven by magnetoelastic interaction in bcc ferromagnetic Ni2MnGaNi_{2}MnGa

We show that the magnetoelastic coupling between the magnetization and the amplitude of a short wavelength phonon enables the existence of a first order premartensitic transition from a bcc to a micromodulated phase in $Ni_{2}MnGa$. Such a magnetoelastic coupling has been experimentally evidenced by AC susceptibility and ultrasonic measurements under applied magnetic field. A latent heat around 9 J/mol has been measured using a highly sensitive calorimeter. This value is in very good agreement with the value predicted by a proposed model.Comment: 4 pages RevTex, 3 Postscript figures, to be published in Physical Review Letter

Correction of adma-induced preeclampsia with the use of phosphodiesterase 5 and selective inhibitor of arginase II ZB49-0010

Simulation experimental ADMA-like preeclampsia was carried out by administering the rats with L-NAME during 14-20 days of pregnancy. In animals, there was an increase in blood pressure, proteinuria, impaired microcirculation in the placenta, the violation of the regulation of vascular tone and destructive changes in the ischemic placenta. The use of phosphodiesterase 5 and selective inhibitor of arginase II ZB49-0010 leads to the expression of morphological and functional correction of violations occurring in modeling of experimental preeclampsi

Premartensitic Transition in Ni2+xMn1-xGa Heusler Alloys

The temperature dependencies of the resistivity and magnetization of a series of Ni2+XMn1-XGa (X = 0 - 0.09) alloys were investigated. Along with the anomalies associated with ferromagnetic and martensitic transitions, well-defined anomalies were observed at the temperature of premartensitic transformation. The premartensitic phase existing in a temperature range 200 - 260 K in the stoichiometric Ni2MnGa is suppressed by the martensitic phase with increasing Ni content and vanishes in Ni2.09Mn0.91Ga composition

Integrating Ukraine into European grid infrastructure

Ukrainian Grid community has established Ukrainian National Grid Initiative (UNGI) which has joined up the major active European projects EGEE and EGI. The community of objectives based on the involvement in world leading scientific projects is elucidated. General features of UNGI and European Grid structures and projects together with various Grid-based applications supported by UNGI are discussed. Current UNGI activities and its future plans in view of realistic computational and human resources are described. The problems and prospects of rapidly progressing Ukrainian Grid infrastructure on the way of international cooperation and integration are illuminated.Украинские специалисты в области грид-технологий начали реализацию Украинской национальной грид-инициативы (УНГИ), которая входит в главные действующие европейские проекты EGEE и EGI. Обоснована перспективность и необходимость участия в ведущих мировых научных проектах. Рассматриваются общие черты и характеристики УНГИ, а также европейских грид-структур и проекттов, акцентируется внимание на возможности решения прикладных грид-задач в рамках УНГИ. Представляются современное состояние УНГИ, ее вычислительный и кадровый потенциал. Описываются проблемы и перспективы развития УНГИ, а также пути и способы международной кооперации.Українські фахівці з грід-технологій розпочали реалізацію Української національної грід-ініціативи (УНГІ), що входить до головних діючих європейських проектів EGEE та EGI. Обґрунтовано перспективність і необхідність участі в провідних світових наукових проектах. Розглядаються загальні риси і властивості УНГІ та європейських грід-структур і проектів, акцентується увага на можливості вирішувати прикладні грід-задачі у рамках УНГІ. Представлено сучасний стан УНГІ, її обчислювальний і кадровий потенціал. Описуються проблеми і перспективи розвитку УНГІ, а також шляхи і способи міжнародної кооперації

Forward Physics at the LHC (Elba 2010)

The papers review the main theoretical and experimental aspects of the Forward Physics at the Large Hadron Collider

On the rise of proton-proton cross-sections at high energies

The rise of the total, elastic and inelastic hadronic cross sections at high energies is investigated by means of an analytical parametrization, with the exponent of the leading logarithm contribution as a free fit parameter. Using derivative dispersion relations with one subtraction, two different fits to proton-proton and antiproton-proton total cross section and rho parameter data are developed, reproducing well the experimental information in the energy region 5 GeV - 7 TeV. The parametrization for the total cross sections is then extended to fit the elastic (integrated) cross section data in the same energy region, with satisfactory results. From these empirical results we extract the energy dependence of several physical quantities: inelastic cross section, ratios elastic/total, inelastic/total cross sections, ratio total-cross-section/elastic-slope, elastic slope and optical point. All data, fitted and predicted, are quite well described. We find a statistically consistent solution indicating: (1) an increase of the hadronic cross sections with the energy faster than the log-squared bound by Froissart and Martin; (2) asymptotic limits 1/3 and 2/3 for the ratios elastic/total and inelastic/total cross sections, respectively, a result in agreement with unitarity. These indications corroborate recent theoretical arguments by Ya. I. Azimov on the rise of the total cross section.Comment: 35 pages, 12 figures, discussions improved with further clarifications, references added and updated, one note added, results and conclusions unchanged. Version to be published in J. Phys. G: Nucl. Part. Phy