Excitation function of elliptic flow in Au+Au collisions and the nuclear matter equation of state

We present measurements of the excitation function of elliptic flow at midrapidity in Au+Au collisions at beam energies from 0.09 to 1.49 GeV per nucleon. For the integral flow, we discuss the interplay between collective expansion and spectator shadowing for three centrality classes. A complete excitation function of transverse momentum dependence of elliptic flow is presented for the first time in this energy range, revealing a rapid change with incident energy below 0.4 AGeV, followed by an almost perfect scaling at the higher energies. The equation of state of compressed nuclear matter is addressed through comparisons to microscopic transport model calculations.Comment: 10 pages, 4 eps figures, submitted for publication. Data files will be available at http://www.gsi.de/~fopiwww/pub

Systematics of pion emission in heavy ion collisions in the 1A GeV regime

Using the large acceptance apparatus FOPI, we study pion emission in the reactions (energies in GeV/nucleon are given in parentheses): 40Ca+40Ca (0.4, 0.6, 0.8, 1.0, 1.5, 1.93), 96Ru+96Ru (0.4, 1.0, 1.5), 96Zr+96Zr (0.4, 1.0, 1.5), 197Au+197Au (0.4, 0.6, 0.8, 1.0, 1.2, 1.5). The observables include longitudinal and transverse rapidity distributions and stopping, polar anisotropies, pion multiplicities, transverse momentum spectra, ratios for positively and negatively charged pions of average transverse momenta and of yields, directed flow, elliptic flow. The data are compared to earlier data where possible and to transport model simulations.Comment: 56 pages,42 figures; to be published in Nuclear Physics

The structure and emission model of the relativistic jet in the quasar 3C279 inferred from radio to high-energy γ-ray observations in 2008-2010

We present time-resolved broadband observations of the quasar 3C279 obtained from multi-wavelength campaigns conducted during the first two years of the Fermi Gamma-ray Space Telescope mission. While investigating the previously reported γ-ray/optical flare accompanied by a change in optical polarization, we found that the optical emission appears to be delayed with respect to the γ-ray emission by about 10days. X-ray observations reveal a pair of "isolated" flares separated by 90 days, with only weak γ-ray/optical counterparts. The spectral structure measured by Spitzer reveals a synchrotron component peaking in the mid-infrared band with a sharp break at the far-infrared band during the γ-ray flare, while the peak appears in the millimeter (mm)/submillimeter (sub-mm) band in the low state. Selected spectral energy distributions are fitted with leptonic models including Comptonization of external radiation produced in a dusty torus or the broad-line region. Adopting the interpretation of the polarization swing involving propagation of the emitting region along a curved trajectory, we can explain the evolution of the broadband spectra during the γ-ray flaring event by a shift of its location from 1pc to 4pc from the central black hole. On the other hand, if the γ-ray flare is generated instead at sub-pc distance from the central black hole, the far-infrared break can be explained by synchrotron self-absorption. We also model the low spectral state, dominated by the mm/sub-mm peaking synchrotron component, and suggest that the corresponding inverse-Compton component explains the steady X-ray emission. © 2012. The American Astronomical Society. All rights reserved.

Multi-wavelength observations of blazar AO 0235+164 in the 2008-2009 flaring state

The blazar AO 0235+164 (z = 0.94) has been one of the most active objects observed by Fermi Large Area Telescope (LAT) since its launch in Summer 2008. In addition to the continuous coverage by Fermi, contemporaneous observations were carried out from the radio to γ-ray bands between 2008 September and 2009 February. In this paper, we summarize the rich multi-wavelength data collected during the campaign (including F-GAMMA, GASP-WEBT, Kanata, OVRO, RXTE, SMARTS, Swift, and other instruments), examine the cross-correlation between the light curves measured in the different energy bands, and interpret the resulting spectral energy distributions in the context of well-known blazar emission models. We find that the γ-ray activity is well correlated with a series of near-IR/optical flares, accompanied by an increase in the optical polarization degree. On the other hand, the X-ray light curve shows a distinct 20 day high state of unusually soft spectrum, which does not match the extrapolation of the optical/UV synchrotron spectrum. We tentatively interpret this feature as the bulk Compton emission by cold electrons contained in the jet, which requires an accretion disk corona with an effective covering factor of 19% at a distance of 100 R g. We model the broadband spectra with a leptonic model with external radiation dominated by the infrared emission from the dusty torus. © 2012. The American Astronomical Society. All rights reserved

The spectral energy distribution of fermi bright blazars

We have conducted a detailed investigation of the broadband spectral properties of the γ-ray selected blazars of the Fermi LAT Bright AGN Sample (LBAS). By combining our accurately estimated Fermi γ-ray spectra with Swift, radio, infra-red, optical, and other hard X-ray/γ-ray data, collected within 3 months of the LBAS data taking period, we were able to assemble high-quality and quasi-simultaneous spectral energy distributions (SED) for 48 LBAS blazars. The SED of these γ-ray sources is similar to that of blazars discovered at other wavelengths, clearly showing, in the usual log ν-log ν Fν representation, the typical broadband spectral signatures normally attributed to a combination of low-energy synchrotron radiation followed by inverse Compton emission of one or more components. We have used these SED to characterize the peak intensity of both the low- and the high-energy components. The results have been used to derive empirical relationships that estimate the position of the two peaks from the broadband colors (i.e., the radio to optical, αro, and optical to X-ray, αox, spectral slopes) and from the γ-ray spectral index. Our data show that the synchrotron peak frequency (νSpeak) is positioned between 1012.5 and 1014.5 Hz in broad-lined flat spectrum radio quasars (FSRQs) and between 10 13 and 1017 Hz in featureless BL Lacertae objects. We find that the γ-ray spectral slope is strongly correlated with the synchrotron peak energy and with the X-ray spectral index, as expected at first order in synchrotron-inverse Compton scenarios. However, simple homogeneous, one-zone, synchrotron self-Compton (SSC) models cannot explain most of our SED, especially in the case of FSRQs and low energy peaked (LBL) BL Lacs. More complex models involving external Compton radiation or multiple SSC components are required to reproduce the overall SED and the observed spectral variability. While more than 50% of known radio bright high energy peaked (HBL) BL Lacs are detected in the LBAS sample, only less than 13% of known bright FSRQs and LBL BL Lacs are included. This suggests that the latter sources, as a class, may be much fainter γ-ray emitters than LBAS blazars, and could in fact radiate close to the expectations of simple SSC models. We categorized all our sources according to a new physical classification scheme based on the generally accepted paradigm for Active Galactic Nuclei and on the results of this SED study. Since the LAT detector is more sensitive to flat spectrum γ-ray sources, the correlation between νSpeak and γ-ray spectral index strongly favors the detection of high energy peaked blazars, thus explaining the Fermi overabundance of this type of sources compared to radio and EGRET samples. This selection effect is similar to that experienced in the soft X-ray band where HBL BL Lacs are the dominant type of blazars. © 2010 The American Astronomical Society

Insights into the high-energy γ-ray emission of Markarian 501 from extensive multifrequency observations in the Fermi era

We report on the γ-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) γ-ray spectrum of Mrk 501 can be well described by a single power-law function with a photon index of 1.78 ± 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of two), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 ± 0.14, and the softest one is 2.51 ± 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3 GeV. In this paper, we also present the first results from the 4.5 month long multifrequency campaign (2009 March 15-August 1) on Mrk 501, which included the Very Long Baseline Array (VLBA), Swift, RXTE, MAGIC, and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The extensive radio to TeV data set from this campaign provides us with the most detailed spectral energy distribution yet collected for this source during its relatively low activity. The average spectral energy distribution of Mrk 501 is well described by the standard one-zone synchrotron self-Compton (SSC) model. In the framework of this model, we find that the dominant emission region is characterized by a size ≲0.1 pc (comparable within a factor of few to the size of the partially resolved VLBA core at 15-43 GHz), and that the total jet power (≃1044 erg s-1) constitutes only a small fraction (∼10-3) of the Eddington luminosity. The energy distribution of the freshly accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3 GeV-10 TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20 GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk 501 is due to relativistic, proton-mediated shocks. We find that the ultrarelativistic electrons and mildly relativistic protons within the blazar zone, if comparable in number, are in approximate energy equipartition, with their energy dominating the jet magnetic field energy by about two orders of magnitude. © 2011. The American Astronomical Society

КООРДИМЕТРИЧЕСКИЕ ИССЛЕДОВАНИЯ ГЛАЗОДВИГАТЕЛЬНЫХ НАРУШЕНИЙ ПРИ «ВЗРЫВНЫХ» ПЕРЕЛОМАХ ГЛАЗНИЦЫ (ОПИСАНИЕ СЛУЧАЕВ)

We report three cases of ‘blow-up’ orbital fractures before and after the surgery. Differential diagnosis of consequences and complications of orbital fractures as well as detection of oculomotor muscles damage are discussed. Restoration of function of oculomotor muscles was monitored after the surgery. To detect the causes of restricted motion of eye bulb and diplopia, coordimetry was used. Coordimetric method was useful in determining nature and localization of oculomotor muscles damage. Repeated coordimetry allowed monitoring of restoration of oculomotor muscles function during treatment and rehabilitation periods in patients with consequences and complications of mid-facial trauma.Приведены три клинических наблюдения больных со «взрывными» переломами орбиты в до- и послеоперационном периоде. Выполнена дифференциальная диагностика последствий и осложнений переломов глазницы, определен характер повреждений глазодвигательных мышц, оценена динамика восстановления их функции в послеоперационном периоде. Методом коордиметрии выявлены причины выраженного ограничения подвижности глазных яблок и диплопии. Коордиметрические исследования позволили достоверно определить характер и локализацию повреждения глазодвигательных мышц. Доказано, что коордиметрические исследования, проведенные в динамике, позволяют проследить восстановление функций глазодвигательных мышц на этапах лечения и реабилитации пациентов с последствиями и осложнениями травмы средней зоны лица

КОМПЬЮТЕРНОЕ МОДЕЛИРОВАНИЕ И ЛАЗЕРНЫЕ ТЕХНОЛОГИИ В РЕАБИЛИТАЦИИ ПАЦИЕНТОВ ПРИ ТРАВМЕ СРЕДНЕЙ ЗОНЫ ЛИЦА

Aim: To assess the kind of damage of musculoskeletal apparatus of eye and orbit. To develop algorithm of laser therapy to restore orbital circulation and algorithm of transcranial laser therapy to improve microcirculation in maxillofacial muscles. Materials and methods: 75 patients with midfacial trauma were examined using laser spectrophotometry and computer modeling of orbital structures in frontal, sagittal, and inclined planes with SSD, MPR and VRT reconstructions (with Mimics software (Materialise, Leuven, Belgium)). To study orbital and maxillofacial microcirculation complex Spectrotest was used. Tissue oxygen concentration (SatO2) and blood filling volume index of microcirculation (Vbf) were measured. Results: After computer modeling, several variants of damage of musculoskeletal apparatus of eye and orbit were identified including oculomotor muscle entrapment in 60% of patients, angular deviation of muscle belly in 30%, muscle contusion – in 45%, orbital hematoma – in 18%, scarring of musculoskeletal apparatus of orbit – in 40%. During early period of trauma of orbital wall and maxillary sinus, Vbf decreased by a mean of 12.5 ± 0.5% compared to normal values, whereas contralateral microcirculation increased by a mean of 28.5 ± 0.1% compared to normal values. Abnormal blood distribution persisted in the long-term, after bone reposition: blood flow increase was found only in 10% of patients. In severe trauma and chronic scarring, local laser irradiation was associated with increase of Vbf bilaterally, but chronically and significantly increased SatO2 indicated impaired tissue trophics and high risk of inflammatory complications. Conclusion: Computer modeling is of great value in the diagnosis and rehabilitation planning in patients with injuries of musculoskeletal apparatus of eye and orbital structures. Laser spectrophotometry is useful for the monitoring of microcirculation before, after the operation and during rehabilitation.Цель – определение характера повреждений структур опорно-мышечного аппарата глаза и глазницы, выработка алгоритма лазерной терапии для восстановления кровообращения в зоне повреждения орбиты и транскраниальной лазерной терапии для нормализации микроциркуляции во всех группах мышц челюстно-лицевой области. Материал и методы. Проанализированы результаты обследования и лечения 75 больных с травмой средней зоны лица с использованием методов лазерной спектрофотометрии и компьютерного моделирования структур орбиты во фронтальной, сагиттальной и наклонных плоскостях с SSD-, MPR- и VRT-реконструкциями. При компьютерном моделировании применялось программное обеспечение Mimics (Materialise, Leuven, Бельгия). Для исследования микроциркуляции тканей орбитальной и челюстно-лицевой областей использовался комплекс Спектротест. При исследовании регистрировались концентрация кислорода в тканях (сатурация (StO2)) и индекс объемного кровенаполнения сосудов микроциркуляторного русла (Vкр). Результаты. Компьютерное моделирование позволило выделить следующие варианты повреждений опорно-мышечного аппарата глаза и глазницы: ущемление глазодвигательной мышцы у 60% больных, угловое смещение мышечного брюшка – 30%, мышечную контузию – 45%, гематомы орбитальной области – 18%, рубцовую деформацию опорно-мышечного аппарата глазницы – 40%. В раннем периоде после травмы при повреждении стенок глазницы и верхнечелюстного синуса в микроциркуляторном русле Vкр снижался в среднем на 12,5 ± 0,5% по сравнению с нормой, при этом на здоровой стороне объем микроциркуляции увеличивался в среднем на 28,5 ± 0,1% по сравнению с нормой. В отдаленном периоде после репозиции костных отломков сохранялось перераспределение объема циркулирующей крови: повышение отмечено только у 10% больных. При тяжелых травмах и длительно существующих рубцовых деформациях локальные воздействия лазерного излучения увеличивали Vкр с двух сторон, но при этом сохранялись достоверно повышенные показатели StО2 (до 25,0 ± 0,6%), что характерно для нарушенной трофики тканей и в катамнезе не исключает развития воспалительных осложнений. Заключение. Метод компьютерного моделирования наиболее информативен при исследовании повреждений опорно-мышечных структур глаза и глазницы и рекомендуется при проведении диагностики и составлении плана реабилитации больных с данной патологией. Метод лазерной спектрофотометрии позволяет проследить в динамике процесс восстановления микроциркуляции тканей в до- и послеоперационном периоде и во время проведения реабилитационных мероприятий