Pension Reform in Russia: First Year of Implementing

From January 1, 2002 Russian embarked on a pension reform to set up a three-pillar pension system and introduce funded principles of retirement pensions to be accumulated for "younger" workers. The new pension includes the flat-rate basic part which is paid to ensure a certain guaranteed minimum income, and the insured and funded parts both of which depend on amounts of insurance contributions and the resulting pension assets registered on an individual basis through the working life. The reform is aimed at improving the pension provision standards in the Russian Federation through ensuring long-term financial stability of the pension system.

Thermal fluctuations in the interacting pion gas

We derive the two-particle fluctuation correlator in a thermal gas of pi-mesons to the lowest order in an interaction due to a resonance exchange. A diagrammatic technique is used. We discuss how this result can be applied to event-by-event fluctuations in heavy-ion collisions, in particular, to search for the critical point of QCD. As a practical example, we determine the shape of the rapidity correlator.Comment: 12 pages, 4 figures, RevTe

The freeze-out mechanism and phase-space density in ultrarelativistic heavy-ion collisions

We explore the consequences of a freeze-out criterion for heavy-ion collisions, based on pion escape probabilities from the hot and dense but rapidly expanding collision region. The influence of the expansion and the scattering rate on the escape probability is studied. The temperature dependence of this scattering rate favors a low freeze-out temperature of ~100 MeV. In general, our results support freeze-out along finite four-volumes rather than sharp three-dimensional hypersurfaces, with high-pt particles decoupling earlier from smaller volumes. We compare our approach to the proposed universal freeze-out criteria using the pion phase-space density and its mean free path.Comment: 8 pages, 2 figures, although conclusions are unchanged, the paper has been re-written and the title has been changed for the sake of better presentatio

РЕЗУЛЬТАТЫ ПРИМЕНЕНИЯ ФОСФОМИЦИНА ДЛЯ ИМПРЕГНАЦИИ ОСТЕОЗАМЕЩАЮЩИХ МАТЕРИАЛОВ ПРИ ЛЕЧЕНИИ ХРОНИЧЕСКОГО ОСТЕОМИЕЛИТА

Aim – to evaluate in the experimental study in vitro the duration of antimicrobial activity of fosfomycin-impregnated bone cement and to study the dynamics of radiological and morphological changes depending on the local antibiotic therapy in two-stage treatment of chronic osteomyelitis in rabbits.Materials and methods. Duration of antimicrobial activity of bone cement (depuy cmw1 gentamicin) with fosfomycin in vitro was studied in comparison to cements with vancomycin and controls without additional antibiotics. Presence of the lysis zone of bacterial cultures was evaluated (Staphylococcus aureus ATCC6538 and ATCC33591, Klebsiella pneumoniae ATCC33495 and Escherichia coli ATCC25922) after application of 10 μl of the solution, collected from the cement samples after incubation for 24 hours. For the in vivo experiment, Chinchilla rabbits (n = 20) with local osteomyelitis of the tibia underwent two-stage treatment where substitution of the bone defect at stage I was performed with PMMA and stage II – with the bioresorbable material based on hydroxyapatite and triclacium phosphate (ReproBone). In an experience group (n = 10) before setting osteoreplacement materials with fosfomycin (group FOSFO), and by control (n = 10) – vancomycin (group VANCO). X-ray imaging was performed on the 1st and 21st day after installation of the cement spacer, and 45th day after substitution of the spacer with the bioresorbable material. Microbiological analysis of the samples was performed intraoperatively and on the 7th, 14th day after each stage. Histological study was conducted in both groups on the 14th, 21th day after stage I and 45th day after stage II of the treatment.Results. Maximal duration of antimicrobial activity in vitro was observed in samples of PMMA with fosfomycin whereas minimal – in control samples of gentamicin-based bone cement. Relief of the infection was attained in all animals while application of fosfomycin resulted in a more rapid elimination of the bacteria. Reaction of the adjacent tissue to the implanted material and results of X-ray imaging in both groups did not differ significantly. Long duration of the broad-spectrum antimicrobial activity of the bone cement with fosfomycin with the comparable perifocal reaction in vivo necessitates further study of the use of this antibiotic in bioresorbable materials for the treatment of osteomyelitis in clinical practice.Цель – оценить в эксперименте in vitro длительность антимикробной активности образцов импрегнированного фосфомицином костного цемента и изучить динамику рентгенологической и морфологической картины в зависимости от локальной антибактериальной терапии при двухэтапном лечении хронического остеомиелита у кроликов.Материал и методы. Изучали in vitro длительность антимикробной активности образцов импрегнированного фосфомицином костного цемента (depuy cmw1 gentamicin) в сравнении с импрегнацией ванкомицином и контрольными образцами без внесения дополнительного антибиотика. Оценивали наличие зоны лизиса бактериальной культуры (Staphylococcus aureus ATCC6538 и ATCC33591, Klebsiella pneumoniae ATCC33495 и Escherichia coli ATCC25922) в области нанесения 10 мкл инкубационного раствора после инкубации образца в течение 24 час. В эксперименте in vivo 20 кроликам породы Шиншилла c локальным очагом остеомиелита большеберцовой кости проводили двухэтапное лечение. На первом этапе костный дефект замещали костным цементом на основе полиметилметакрилата (ПММА), на втором этапе – биорезорбируемым материалом на основе гидроксиапатита и трикальцийфосфата (ReproBone). В опытной группе (n = 10) перед установкой остеозамещающие материалы импрегнировали фосфомицином (группа ФОСФО), а в контрольной группе (n = 10) – ванкомицином (группа ВАНКО). Рентгенологические исследования выполняли в первые и 21-е сутки после установки цементного спейсера, на 45-е сутки после удаления цементного спейсера и укладки биорезорбируемого материала. Бактериологические исследования выполняли интраоперационно, на 7-е и 14-е сутки после каждого этапа. Морфологические исследования выполняли в обеих группах на 14-е и 21-е сутки после первого этапа и на 45-е сутки после второго этапа лечения.Результаты. Максимальная продолжительность антимикробной активности in vitro установлена при использовании ПММА с фосфомицином, минимальная – для контрольных образцов из официнального гентамицин-содержащего цемента. В эксперименте in vivo у всех животных было достигнуто купирование инфекционного процесса, однако применение фосфомицина приводило к более быстрой эрадикации возбудителя. Реакции тканей, окружающих имплантированный материал, в обеих группах экспериментальных животных различались незначительно, рентгенологическая картина была схожей. Большая длительность антимикробного действия образцов костного цемента с фосфомицином в отношении широкого спектра возбудителей при сопоставимых перифокальных реакциях в эксперименте in vivo делает перспективным дальнейшее изучение данного антибиотика в составе остеозамещающих материалов при лечении остеомиелита в клинической практике

Hadronic observables from SIS to SPS energies - anything strange with strangeness ?

We calculate $p, \pi^\pm, K^\pm$ and $\Lambda$(+$\Sigma^0$) rapidity distributions and compare to experimental data from SIS to SPS energies within the UrQMD and HSD transport approaches that are both based on string, quark, diquark ($q, \bar{q}, qq, \bar{q}\bar{q}$) and hadronic degrees of freedom. The two transport models do not include any explicit phase transition to a quark-gluon plasma (QGP). It is found that both approaches agree rather well with each other and with the experimental rapidity distributions for protons, $\Lambda$'s, $\pi^\pm$ and $K^\pm$. Inspite of this apparent agreement both transport models fail to reproduce the maximum in the excitation function for the ratio $K^+/\pi^+$ found experimentally between 11 and 40 A$\cdot$GeV. A comparison to the various experimental data shows that this 'failure' is dominantly due to an insufficient description of pion rapidity distributions rather than missing 'strangeness'. The modest differences in the transport model results -- on the other hand -- can be attributed to different implementations of string formation and fragmentation, that are not sufficiently controlled by experimental data for the 'elementary' reactions in vacuum.Comment: 46 pages, including 15 eps figures, to be published in Phys. Rev.

Particlization in hybrid models

In hybrid models, which combine hydrodynamical and transport approaches to describe different stages of heavy-ion collisions, conversion of fluid to individual particles, particlization, is a non-trivial technical problem. We describe in detail how to find the particlization hypersurface in a 3+1 dimensional model, and how to sample the particle distributions evaluated using the Cooper-Frye procedure to create an ensemble of particles as an initial state for the transport stage. We also discuss the role and magnitude of the negative contributions in the Cooper-Frye procedure.Comment: 18 pages, 28 figures, EPJA: Topical issue on "Relativistic Hydro- and Thermodynamics"; version accepted for publication, typos and error in Eq.(1) corrected, the purpose of sampling and change from UrQMD to fluid clarified, added discussion why attempts to cancel negative contributions of Cooper-Frye are not applicable her

Parton coalescence at RHIC

Using a covariant coalescence model, we study hadron production in relativistic heavy ion collisions from both soft partons in the quark-gluon plasma and hard partons in minijets. Including transverse flow of soft partons and independent fragmentation of minijet partons, the model is able to describe available experimental data on pion, kaon, and antiproton spectra. The resulting antiproton to pion ratio is seen to increase at low transverse momenta and reaches a value of about one at intermediate transverse momenta, as observed in experimental data at RHIC. A similar dependence of the antikaon to pion ratio on transverse momentum is obtained, but it reaches a smaller value at intermediate transverse momenta. At high transverse momenta, the model predicts that both the antiproton to pion and the antikaon to pion ratio decrease and approach those given by the perturbative QCD. Both collective flow effect and coalescence of minijet partons with partons in the quark-gluon plasma affect significantly the spectra of hadrons with intermediate transverse momenta. Elliptic flows of protons, Lambdas, and Omegas have also been evaluated from partons with elliptic flows extracted from fitting measured pion and kaon elliptic flows, and they are found to be consistent with available experimental data.Comment: 12 pages, 11 figure

Phi meson production in Au+Au and p+p collisions at sqrt (s)=200 GeV

We report the STAR measurement of Phi meson production in Au+Au and p+p collisions at sqrt (s)=200 GeV. Using the event mixing technique, the Phi spectra and yields are obtained at mid-rapidity for five centrality bins in Au+Au collisions and for non-singly-diffractive p+p collisions. It is found that the Phi transverse momentum distributions from Au+Au collisions are better fitted with a single-exponential while the p+p spectrum is better described by a double-exponential distribution. The measured nuclear modification factors indicate that Phi production in central Au+Au collisions is suppressed relative to peripheral collisions when scaled by the number of binary collisions. The systematics of versus centrality and the constant Phi/K- ratio versus beam species, centrality, and collision energy rule out kaon coalescence as the dominant mechanism for Phi production.Comment: 6 pages, 3 figures, submitted to Phys. Rev. Let

Energy and system size dependence of \phi meson production in Cu+Cu and Au+Au collisions

We study the beam-energy and system-size dependence of \phi meson production (using the hadronic decay mode \phi -- K+K-) by comparing the new results from Cu+Cu collisions and previously reported Au+Au collisions at \sqrt{s_NN} = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented are from mid-rapidity (|y|<0.5) for 0.4 < pT < 5 GeV/c. At a given beam energy, the transverse momentum distributions for \phi mesons are observed to be similar in yield and shape for Cu+Cu and Au+Au colliding systems with similar average numbers of participating nucleons. The \phi meson yields in nucleus-nucleus collisions, normalised by the average number of participating nucleons, are found to be enhanced relative to those from p+p collisions with a different trend compared to strange baryons. The enhancement for \phi mesons is observed to be higher at \sqrt{s_NN} = 200 GeV compared to 62.4 GeV. These observations for the produced \phi(s\bar{s}) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems.Comment: 20 pages and 5 figure