Shower center of gravity and interaction characteristics

The shower center of gravity is used for studying the interconnection between shower longitudinal profile and hadronic interaction characteristics. The equations for the shower originated by high energy proton in the atmosphere are written and, within certain simplifications, solved for the case of logarithmically decreasing interaction length of hadrons in the air. The obtained expression explicitely splits into center of gravity of the purely electromagnetic cascade at the primary proton energy and modification of that by hadronic cascading and provides transparent view of the way in which hadronic interaction characteristics determine the longitudinal shower development

High energy neutrino yields from astrophysical sources II: Magnetized sources

We calculate the yield of high energy neutrinos produced in astrophysical sources for arbitrary interaction depths $\tau_0$ and magnetic field strengths $B$. We take into account energy loss processes like synchrotron radiation and diffusion of charged particles in turbulent magnetic fields as well as the scattering of secondaries on background photons and the direct production of charm neutrinos. Meson-photon interactions are simulated with an extended version of the SOPHIA model. Diffusion leads to an increased path-length before protons leave the source of size R_s and therefore magnetized sources lose their transparency below the energy $E\sim 10^{18}{\rm eV} (R_s/{\rm pc}) (B/{\rm mG}) \tau_0^{1/\alpha}$, with $\alpha=1/3$ and 1 for Kolmogorov and Bohm diffusion, respectively. Moreover, the neutrino flux is suppressed above the energy where synchrotron energy losses become important for charged particles. As a consequence, the energy spectrum and the flavor composition of neutrinos are strongly modified both at low and high energies even for sources with \tau_0\lsim 1.Comment: 15 pages, 16 figure

Impact of Uncertainties in Hadron Production on Air-Shower Predictions

At high energy, cosmic rays can only be studied by measuring the extensive air showers they produce in the atmosphere of the Earth. Although the main features of air showers can be understood within a simple model of successive interactions, detailed simulations and a realistic description of particle production are needed to calculate observables relevant to air shower experiments. Currently hadronic interaction models are the main source of uncertainty of such simulations. We will study the effect of using different hadronic models available in CORSIKA and CONEX on extensive air shower predictions.Comment: 12 pages, 6 figures, to appear in the proceedings of International Conference on Interconnection between High Energy Physics and Astroparticle Physics: From Colliders to Cosmic Rays, Prague, Czech Republic, 7-13 Sep 200

Muon content of ultra-high-energy air showers: Yakutsk data versus simulations

We analyse a sample of 33 extensive air showers (EAS) with estimated primary energies above 2\cdot 10^{19} eV and high-quality muon data recorded by the Yakutsk EAS array. We compare, event-by-event, the observed muon density to that expected from CORSIKA simulations for primary protons and iron, using SIBYLL and EPOS hadronic interaction models. The study suggests the presence of two distinct hadronic components, ``light'' and ``heavy''. Simulations with EPOS are in a good agreement with the expected composition in which the light component corresponds to protons and the heavy component to iron-like nuclei. With SYBILL, simulated muon densities for iron primaries are a factor of \sim 1.5 less than those observed for the heavy component, for the same electromagnetic signal. Assuming two-component proton-iron composition and the EPOS model, the fraction of protons with energies E>10^{19} eV is 0.52^{+0.19}_{-0.20} at 95% confidence level.Comment: 8 pages, 3 figures; v2: replaced with journal versio

Респираторная поддержка при тромбоэмболии легочной артерии (обзор)

Pulmonary artery thromboembolia (PATE) is not a clinical entity as such, but a complication of different diseases and conditions leading to deep thrombosis in the low tension circulation system, right cardiac chambers or causing local thrombosis in the pulmonary artery system. PATE is characterized by complex pathogenesis of respiratory failure of varying severity, which makes it difficult to choose a respiratory support technique.Purpose of the overview: to show advantages of different respiratory support techniques and prospects of high-flux oxygen therapy with regard to PATE pathophysiology.82 sources were selected based on the principle of combining clinical and experimental data from papers published over the recent 5 years and earlier that are still relevant for medical practice.The overview presents the structure of main causes and prevalence of PATE and considers thrombogenesis stages and predominant manifestations of respiratory failure during PATE occurring due to inconsistency between pulmonary ventilation and perfusion. Review discusses five methods of respiratory therapy in PATE patients: low-flux and high-flux oxygen therapy, non-invasive and invasive artificial lung ventilation, extracorporeal blood oxygenation. Finally, the paper shows the efficacy and limitations of these methods.Conclusion. High-flux oxygen therapy seems to be the most effective and promising technique in PATE patients thanks to absence of adverse cardiohemodynamic consequences, subjective comfort for patients, and relation to minimal risks of secondary infectious complications.Nevertheless, the clinical experience accumulated is insufficient to make an absolute choice of one particular technique for respiratory support during PATE. It is necessary to continue investigating the clinical efficacy of high-flux oxygen therapy in the specific population of patients who experienced PATE.Тромбоэмболия легочной артерии (ТЭЛА) — не самостоятельная нозологическая единица, а осложнение различных заболеваний и состояний, приводящих к возникновению глубоких тромбозов в венозной системе, правых камерах сердца, либо вызывающих местный тромбоз в системе легочной артерии. ТЭЛА характеризуется сложностью патогенеза развития дыхательной недостаточности различной степени выраженности, что обуславливает сложность выбора способов респираторной поддержки.Цель обзора. Показать возможности различных методов респираторной поддержки и перспективы применения высокопоточной оксигенотерапии с учетом патофизиологических особенностей ТЭЛА.Отбор 82 источников проводили по принципу сочетания клинических и экспериментальных данных из источников последних 5 лет и более ранних, сохранивших актуальность для медицинской практики.В обзоре представили структуру основных причин и частоту распространения ТЭЛА; рассмотрели этапы тромбогенеза и основные проявления дыхательной недостаточности при ТЭЛА, возникающие при несоответствии вентиляции и перфузии легких; привели 5 методов респираторной терапии у больных с ТЭЛА: низкопоточную и высокопоточную оксигенотерапию, неинвазивную и инвазивную искусственную вентиляцию легких, экстракорпоральную оксигенацию крови; показали эффективность и ограничения этих методов.Заключение. Метод высокопоточной оксигенотерапии представляется наиболее эффективным и перспективным у больных с ТЭЛА в связи с отсутствием негативных кардиогемодинамических последствий, субъективной комфортностью для пациентов, а также ввиду соотношения с минимальными рисками вторичных инфекционных осложнений.Тем не менее, накопленного клинического опыта недостаточно для однозначного выбора того или иного метода респираторной поддержки при ТЭЛА. Необходимо продолжение изучения клинической эффективности высокопоточной оксигенотерапии у специфического контингента больных, перенесших ТЭЛА

Consistent Treatment of Soft and Hard Processes in Hadronic Interactions

The QCD improved parton model is a very successful concept to treat processes in hadronic interactions, whenever large partonic transverse momenta are involved. However, cross sections diverge in the limit p_T -> 0, and the usual treatment is the definition of a lower cutoff p_T_min, such that processes with a smaller p_T -- so-called soft processes -- are simply ignored, which is certainly not correct for example at RHIC energies. A more consistent procedure amounts to introduce a technical parameter Q_0^2, referred to as soft virtuality scale, which is nothing but an artificial borderline between soft and hard physics. We will discuss such a formalism, which coincides with the improved parton model for high p_T processes and with the phenomenological treatment of soft scattering, when only small virtualities are involved. The most important aspect of our approach is that it allows to obtain a smooth transition between soft and hard scattering, and therefore no artificial dependence on a cutoff parameter should appear.Comment: 19 pages, 19 figure

A model for net-baryon rapidity distribution

In nuclear collisions, a sizable fraction of the available energy is carried away by baryons. As the baryon number is conserved, the net-baryon $B-\bar{B}$ retains information on the energy-momentum carried by the incoming nuclei. A simple and consistent model for net-baryon production in high energy proton-proton and nucleus-nucleus collisions is presented. The basic ingredients of the model are valence string formation based on standard PDFs with QCD evolution and string fragmentation via the Schwinger mechanism. The results of the model are presented and compared with data at different centre-of-mass energies and centralities, as well as with existing models. These results show that a good description of the main features of net-baryon data is possible in the framework of a simplistic model, with the advantage of making the fundamental production mechanisms manifest.Comment: 9 pages, 12 figures; in fig. 11 a) the vertical scale was correcte

Сочетанная терапия оксидом азота и сурфактантом-BL при остром респираторном дистресс-синдроме после операций с искусственным кровообращением

The paper presents the results of a clinical trial of Surfactant-BL in adult patients with acute respiratory distress syndrome. Pulmonary biomechanics and gas exchange are shown to improve, the duration of respiratory support and the length of stay at an intensive care unit decrease, and the frequency of pyoseptic pulmonary complications reduces with early endotracheal administration of Surfactant-BL under artificial ventilation in acute respiratory distress syndrome.Целью настоящего исследования была сравнительная оценка эффективности ингаляционного оксида азота и комбинации ингаляционного оксида азота с сурфактантом-BL в комплексной терапии ОРДС после операций с ИК. В исследование включили 53 больных в возрасте от 21 до 76 лет. Исследование выявило, что при ОРДС, осложняющем операции с искусственным кровообращением, назначение сурфактанта-BL на фоне терапии ингаляционным оксидом азота повышает эффективность влияния ингаляционного оксида азота на артериальную оксигенацию, обеспечивает ускорение регресса нарушений оксигенирующей функции легких, сокращает продолжительность ИВЛ и укорачивает сроки госпитализации в отделении интенсивной терапии