Shadowing Effects on Vector Boson Production

We explore how nuclear modifications to the nucleon structure functions, shadowing, affect massive gauge boson production in heavy ion collisions at different impact parameters. We calculate the dependence of $Z^0$, $W^+$ and $W^-$ production on rapidity and impact parameter to next-to-leading order in Pb+Pb collisions at 5.5 TeV/nucleon to study quark shadowing at high $Q^2$. We also compare our Pb+Pb results to the $pp$ rapidity distributions at 14 TeV.Comment: 25 pages ReVTeX, 12 .eps figures, NLO included, version accepted for publication in Physical Review

The Effect of Shadowing on Initial Conditions, Transverse Energy and Hard Probes in Ultrarelativistic Heavy Ion Collisions

The effect of shadowing on the early state of ultrarelativistic heavy ion collisions is investigated along with transverse energy and hard process production, specifically Drell-Yan, $J/\psi$, and $\Upsilon$ production. We choose several parton distributions and parameterizations of nuclear shadowing, as well as the spatial dependence of shadowing, to study the influence of shadowing on relevant observables. Results are presented for Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV and Pb+Pb collisions at $\sqrt{s_{NN}} = 5.5$ TeV.Comment: Submitted to Phys. Rev.

Heavy Quark Photoproduction in Ultra-peripheral Heavy Ion Collisions

Heavy quarks are copiously produced in ultra-peripheral heavy ion collisions. In the strong electromagnetic fields, c c-bar and b b-bar are produced by photonuclear and two-photon interactions; hadroproduction can occur in grazing interactions. We present the total cross sections, quark transverse momentum and rapidity distributions, as well as the Q Q-bar invariant mass spectra from the three production channels. We consider AA and pA collisions at the Relativistic Heavy Ion Collider and Large Hadron Collider. We discuss techniques for separating the three processes and describe how the AA to pA production ratios might be measured accurately enough to study nuclear shadowing.Comment: Minor changes to satisfy referees and typo fixes; 52 pages including 17 figure

Femtosecond laser writing of subwave one-dimensional quasiperiodic nanostructures on a titanium surface

One-dimensional quasiperiodic structures whose period is much smaller than the wavelength of exciting radiation have been obtained on a titanium surface under the multipulse action of linearly polarized femtosecond laser radiation with various surface energy densitiesye

Rigorous analysis of extremely asymmetrical scattering of electromagnetic waves in slanted periodic gratings

Extremely asymmetrical scattering (EAS) is a new type of Bragg scattering in thick, slanted, periodic gratings. It is realised when the scattered wave propagates parallel to the front boundary of the grating. Its most important feature is the strong resonant increase in the scattered wave amplitude compared to the amplitude of the incident wave: the smaller the grating amplitude, the larger the amplitude of the scattered wave. In this paper, rigorous numerical analysis of EAS is carried out by means of the enhanced T-matrix algorithm. This includes investigation of harmonic generation inside and outside the grating, unusually strong edge effects, fast oscillations of the incident wave amplitude in the grating, etc. Comparison with the previously developed approximate theory is carried out. In particular, it is demonstrated that the applicability conditions for the two-wave approximation in the case of EAS are noticeably more restrictive than those for the conventional Bragg scattering. At the same time, it is shown that the approximate theory is usually highly accurate in terms of description of EAS in the most interesting cases of scattering with strong resonant increase of the scattered wave amplitude. Physical explanation of the predicted effects is presented.Comment: 14 pages, 7 figures; v2: corrections to metadata and bibliographical info in preprin

Зміни динамічних процесів скорочення скелетних м’язів при дії стресових факторів

Change of fibers’ dynamic parameters of the frog Rana temporaria skeletal muscle m. tibialis traction under influence of modulated stimulation and aluminium chloride solutions was studied. At 10-4,5·10-4 and 10‑3 M·l-1 concentrations of aluminium chloride the nonlinear decrease of the muscle fibers’ traction parameters was observed.Досліджено зміну динамічних параметрів скорочення скелетних волокон м’яза m. tibialis жаби Rana temporaria в ізотонічному режимі під впливом модульованої стимуляції та розчинів хлориду алюмінію. Встановлено, що в результаті використання розчинів хлориду алюмінію в концентраціях 10-4,5·10-4, 10-3 моль/л спостерігається нелінійне зниження параметрів скорочення м’язових волокон. Досліджено зміну динамічних параметрів скорочення скелетних волокон м’яза m. tibialis жаби Rana temporaria в ізотонічному режимі під впливом модульованої стимуляції та розчинів хлориду алюмінію. Встановлено, що в результаті використання розчинів хлориду алюмінію в концентраціях 10-4,5·10-4, 10-3 моль/л спостерігається нелінійне зниження параметрів скорочення м’язових волокон.

Nontrivial dependence of dielectric stiffness and SHG on dc bias in relaxors and dipole glasses

Dielectric permittivity and Second Harmonic Generation (SHG) studies in the field-cooled mode show a linear dependence of dielectric stiffness (inverse dielectric permittivity) on dc bias in PMN-PT crystals and SHG intensity in KTaO$_{3}$:Li at small Li concentrations. We explain this unusual result in the framework of a theory of transverse, hydrodynamic-type, instability of local polarization.Comment: 5 figure

Metal Cluster's Effect on the Optical Properties of Cesium Bromide Thin Films

Cesium Bromide films grown of glass substrates by thermal evaporation showed interesting optical properties. The UV-visible absorption spectra showed peaks which showed red shift with time. Structural and morphological studies suggested decrease in grain size with time which was unusual. Theoretical simulation shows the optical behaviour to be due to surface plasmon resonance resulting from Cesium clyindrical rods embedded in the films.Comment: 22 pages and 10 figure

Пенообразование растворов поливинилового спирта с разной молекулярной массой в воде

Objectives. Investigation of aqueous polyvinyl alcohol (PVA) foaming process and the influence of its water solution structure, when possessed of different molecular weights and concentrations, on foaming multiplicity.Methods. Solution foaming analysis was performed on the data of dynamic light scattering obtained on the Zetasizer Nano particle analyzer.Results. In this work, the foaming ability and foaming multiplicity of aqueous PVA solutions (as a main component for obtaining special-purpose foams) have been studied. It is shown that PVA solutions in water are colloidal dispersed systems consisting of different-sized associates (from 4.8 to 68.1 nm), depending on the molecular weight of PVA. Dependencies of aqueous PVA solution foaming multiplicities on the concentration, molecular weight, and solution temperature were given. Optimal values of concentration and molecular PVA weight, as well as optimal foaming process conditions from aqueous PVA solutions, were established.Conclusions. Increasing PVA concentrations in aqueous solutions cause foaming multiplicity to decrease for all molecular weights by 1.5 times, and increasing molecular weight increases foaming multiplicity by 2 times. The foaming ratio of aqueous PVA solutions with different concentrations and molecular weights (depending on a solution temperature characterized by a maximum of 30 °C) is associated with decreased viscosity and surface tension.Цели. Исследовать процесс пенообразования водных растворов поливинилового спирта (ПВС) с различной молекулярной массой и концентрацией и влияние их структуры на кратность их вспенивания.Методы. Анализ пенообразования растворов проводили по данным динамического светорассеяния, полученным на анализаторе частиц Zetasizer Nano.Результаты. В работе изучена пенообразующая способность и кратность вспенивания водных растворов ПВС как одного из основных компонентов получения пен специального назначения. Показано, что растворы ПВС в воде представляют собой коллоидные дисперсные системы, состоящие из ассоциатов с разными размерами (от 4.8 до 68.1 нм) в зависимости от молекулярной массы ПВС. Приведены зависимости кратности вспенивания водных растворов ПВС от концентрации, молекулярной массы и температуры раствора. Приведены значения оптимальной концентрации и молекулярной массы ПВС, а также установлены оптимальные условия процесса пенообразования из водных растворов ПВС.Выводы. Установлено, что с ростом концентрации водных растворов ПВС кратность вспенивания снижается для всех молекулярных масс приблизительно в 1.5 раза, а с увеличением молекулярной массы она возрастает примерно в 2 раза. Кратность вспенивания водных растворов ПВС с разной концентрацией и молекулярной массой в зависимости от температуры раствора характеризуется максимумом при 30 °C, что связано с уменьшением вязкости и снижением поверхностного натяжения растворов

Hard X-ray Bursts Recorded by the IBIS Telescope of the INTEGRAL Observatory in 2003-2009

To find X-ray bursts from sources within the field of view of the IBIS/INTEGRAL telescope, we have analysed all the archival data of the telescope available at the time of writing the paper (the observations from January 2003 to April 2009). We have detected 834 hard (15-25 keV) X-ray bursts, 239 of which were simultaneously recorded by the JEM-X/INTEGRAL telescope in the standard X-ray energy range. More than 70% of all bursts (587 events) have been recorded from the well-known X-ray burster GX 354-0. We have found upper limits on the distances to their sources by assuming that the Eddington luminosity limit was reached at the brightness maximum of the brightest bursts.Comment: 18 pages, 2 figures, 2 table