The role of computer engineering and new information technologies in developing innovations for science and education

In this article we are talking about the role of information technologies in improving the efficiency of labor in the scientific and educational spheres of lifeВ данной статье речь идет о роли информационных технологий в повышении эффективности труда в научной и образовательной сферах жизнедеятельност

HIV-Infektion : Update 2009 für Hausärzte. Teil 1

Quintessenz: In der Schweiz werden jährlich >750 HIV-Infektionen neu diagnostiziert. Die Ansteckung geschieht via Blut oder Sex, und nicht bei alltäglichen sozialen Kontakten. Die CD4-Lymphozytenzahl ist bestens etabliert zur Messung der Immunsuppression. Die grösste Gefahr opportunistischer Infekte droht bei CD4-Werten <200/μl. Dank antiretroviraler Therapie (ART) sollten viele HIV-infizierte Patienten in der Schweiz eine quasi normale Lebenserwartung haben. Momentan ist eine ART bei CD4-Werten <350/μl indiziert. Die HIV-Diagnose wird auch in der Schweiz häufig zu spät gestellt. Hausärzte spielen bei der frühzeitigen Diagnosestellung (grosszügiges Anbieten von HIV-Tests) und bei der Prävention von Immundefizienz und opportunistischen Komplikationen eine entscheidende Rolle. P Bei HIV-Neudiagnose soll der Patient einem HIV-Spezialisten zugewiesen werden, um weitere Abklärungen durchzuführen und die Indikation zum ART-Beginn zu stellen

Formation of Nuclear Spirals in Barred Galaxies

We have performed smoothed particle hydrodynamics (SPH) simulations for the response of the gaseous disk to the imposed moderately strong non-axisymmetric potentials. The model galaxies are composed of the three stellar components (disk, bulge and bar) and two dark ones (supermassive black hole and halo) whose gravitational potentials are assumed to be invariant in time in the frame corotating with the bar. We found that the torques alone generated by the moderately strong bar that gives the maximum of tangential-to-radial force ratio as $(F_{Tan}/F_{Rad})_{max}= 0.3$ are not sufficient to drive the gas particles close to the center due to the barrier imposed by the inner Lindblad resonances (ILRs). In order to transport the gas particles towards the nucleus ($r<100$ pc), a central supermassive black hole (SMBH) and high sound speed of the gas are required to be present. The former is required to remove the inner inner Lindblad resonance (IILR) that prevents gas inflow close to the nucleus, while the latter provides favourable conditions for the gas particles to lose their angular momentum and to spiral in. Our models that have no IILR show the trailing nuclear spirals whose innermost parts reach close to the center in a curling way when the gas sound speed is $c_{s} \gtrsim 15$ km s$^{-1}$. They resemble the symmetric two-armed nuclear spirals observed in the central kiloparsec of spiral galaxies. We found that the symmetric two-armed nuclear spirals are formed by the hydrodynamic spiral shocks caused by the gravitational torque of the bar in the presence of a central SMBH that can remove IILR when the sound speed of gas is high enough to drive a large amount of gas inflow deep inside the ILR. However, the detailed morphology of nuclear spirals depends on the sound speed of gas.Comment: 38 pages, 10 figures, accepted for publication in Ap

The origin and orbit of the old, metal-rich, open cluster NGC 6791: Insights from kinematics

NGC 6791 is a unique stellar system among Galactic open clusters being at the same time one of the oldest open clusters and the most metal rich. Combination of its properties is puzzling and poses question of its origin. One possible scenario is that the cluster formed close to the Galactic Center and later migrated outwards to its current location. In this work we study the cluster's orbit and investigate the possible migration processes which might have displaced NGC 6791 to its present-day position, under the assumption that it actually formed in the inner disk. To this aim we performed integrations of NGC 6791's orbit in a potential consistent with the main Milky Way parameters. In addition to analytical expressions for halo, bulge and disk, we also consider the effect of bar and spiral arm perturbations, which are expected to be very important for the disk dynamical evolution, especially inside the solar circle. Starting from state-of-the art initial conditions for NGC 6791, we calculate 1000 orbits back in time for about 1 Gyr turning on and off different non-axisymmetric components of the global potential. We then compare statistical estimates of the cluster's recent orbital parameters with the orbital parameters of 10^4 test-particles originating close to the Galactic Center (having initial galocentric radii in the range of 3-5 kpc) and undergoing radial migration during 8 Gyr of forward integration. We find that a model which incorporates a strong bar and spiral arm perturbations can indeed be responsible for the migration of NGC 6791 from the inner disk (galocentric radii of 3-5 kpc) to its present-day location. Such a model can provide orbital parameters which are close enough to the observed ones. However, the probability of this scenario as it results from our investigations is very low.Comment: 11 pages, 9 figures, 7 tables, accepted for publication in A&A || v2: minor changes to match the published versio

Development and validation of a risk score for chronic kidney disease in HIV infection using prospective cohort data from the D:A:D study.

Chronic kidney disease (CKD) is a major health issue for HIV-positive individuals, associated with increased morbidity and mortality. Development and implementation of a risk score model for CKD would allow comparison of the risks and benefits of adding potentially nephrotoxic antiretrovirals to a treatment regimen and would identify those at greatest risk of CKD. The aims of this study were to develop a simple, externally validated, and widely applicable long-term risk score model for CKD in HIV-positive individuals that can guide decision making in clinical practice

Equilibrium Disk-Bulge-Halo Models for the Milky Way and Andromeda Galaxies

We describe a new set of self-consistent, equilibrium disk galaxy models that incorporate an exponential disk, a Hernquist model bulge, an NFW halo and a central supermassive black hole. The models are derived from explicit distribution functions for each component and the large number of parameters permit detailed modeling of actual galaxies. We present techniques that use structural and kinematic data such as radial surface brightness profiles, rotation curves and bulge velocity dispersion profiles to find the best-fit models for the Milky Way and M31. Through N-body realizations of these models we explore their stability against the formation of bars. The models permit the study of a wide range of dynamical phenomenon with a high degree of realism.Comment: 58 pages, 20 figures, submitted to the Astrophysical Journa