Stellar Dynamics at the Galactic Center with an Extremely Large Telescope

We discuss experiments achievable via monitoring of stellar dynamics near the massive black hole at the Galactic center with a next generation, extremely large telescope (ELT). Given the likely observational capabilities of an ELT and current knowledge of the stellar environment at the Galactic center, we synthesize plausible samples of stellar orbits around the black hole. We use the Markov Chain Monte Carlo method to evaluate the constraints that orbital monitoring places on the matter content near the black hole. Results are expressed as functions of the number N of stars with detectable orbital motions and the astrometric precision dtheta and spectroscopic precision dv at which stellar proper motions and radial velocities are monitored. For N = 100, dtheta = 0.5 mas, and dv = 10 km/s -- a conservative estimate of the capabilities of a 30 meter telescope -- the extended matter distribution enclosed by the orbits will produce measurable deviations from Keplerian motion if >1000 Msun is enclosed within 0.01 pc. The black hole mass and distance to the Galactic center will be measured to better than ~0.1%. Lowest-order relativistic effects, such as the prograde precession, will be detectable if dtheta < 0.5 mas. Higher-order effects, including frame dragging due to black hole spin, requires dtheta < 0.05 mas, or the favorable discovery of a compact, highly eccentric orbit. Finally, we calculate the rate at which monitored stars undergo detectable nearby encounters with background stars. Such encounters probe the mass function of stellar remnants that accumulate near the black hole. We find that ~30 encounters will be detected over a 10 yr baseline for dtheta = 0.5 mas.Comment: 14 pages, 5 figures; discussion no longer aperture-specific (TMT -> ELT), matches ApJ versio

The role of a pharmacist in prevention and detection of OTC drug interactions: Nominal group technique

Introduction: Nowadays number of newly approved OTC medicines continuously increases, which can make certain difficulties in drug dispensing process. This fact particularly relates to drug-drug interactions-problems due to lack of data and insufficient of knowledge about the interactions. Aim: To identify the problems pharmacists face when dispensing OTC drugs and to recommend concrete ideas and methods for improving system for detecting OTC drugs interactions. Participants and method: The study was carried out in accordance with methodological principles of nominal group technique. Two meetings of nominal group were conducted, enrolling pharmacists employed in public pharmacies. During the meetings, moderator imposed aset of questions to participants, who gave answers in the form of individual statements. In order to examine agreement of the participants about the individual statements, at the end of both sessions the statements were rated on a Likert's scale. Meetings were recorded and audio recordings later used for qualitative analysis. Results: Nine pharmacists of both sex (7/2 females/males) participated in this study. Average age of the participants was 25.0±1.0 years. During nominal group meetings, participants presented 30 statements on 7 research questions, and after the second meeting agreement was reached about 29 of them. Qualitative analysis of data indicated three categories of statements: (1) pharmacists' knowledge of OTC drugs interactions, (2) problems pharmacists face when dispensing OTC drugs and (3) options of improving system for prevention and detection of OTC drugs interactions. Conclusion: For adequate prevention of potential OTC drugs interactions it is necessary to make guidelines with recommendations referring to proper dispensing procedure and to use regularly available online interaction checkers

Long Term Evolution of Massive Black Hole Binaries

The long-term evolution of massive black hole binaries at the centers of galaxies is studied in a variety of physical regimes, with the aim of resolving the ``final parsec problem,'' i.e., how black hole binaries manage to shrink to separations at which emission of gravity waves becomes efficient. A binary ejects stars by the gravitational slingshot and carves out a loss cone in the host galaxy. Continued decay of the binary requires a refilling of the loss cone. We show that the standard treatment of loss cone refilling, derived for collisionally relaxed systems like globular clusters, can substantially underestimate the refilling rates in galactic nuclei. We derive expressions for non-equilibrium loss-cone dynamics and calculate time scales for the decay of massive black hole binaries following galaxy mergers, obtaining significantly higher decay rates than heretofore. Even in the absence of two-body relaxation, decay of binaries can persist due to repeated ejection of stars returning to the nucleus on eccentric orbits. We show that this recycling of stars leads to a gradual, approximately logarithmic dependence of the binary binding energy on time. We derive an expression for the loss cone refilling induced by the Brownian motion of a black hole binary. We also show that numerical N-body experiments are not well suited to probe these mechanisms over long times due to spurious relaxation.Comment: Replaced to match the accepted version, ApJ, 596 (2003

Expression of p53 protein in Barrett’s adenocarcinoma and adenocarcinoma of the gastric cardia and antrum

Background/Aim. Most studies of esophageal and gastric adenocarcinomas have shown a very high rate of p53 gene mutation and/or protein overexpression, but the influence of the tumor site upon the frequency of p53 protein expression has not been evaluated (gastroesophageal junction, Barret's esophagus, and antrum). The aim of our study was to analyze the correlation between the selected clinico-pthological parameters, and p53 protein overexpression in regards to the particular tumor location. Methods. The material comprised 66 surgical specimens; 10 were Barrett’s carcinomas, 25 adenocarcinomas of the gastric cardia (type II adenocarcinoma of the esophagogastric junction - EGJ), and 31 adenocarcinomas of the antrum. Immunostaining for p53 protein was performed on formalin-fixed, paraffin-embedded tissue sections, using the alkaline phosphatase - antialkaline phosphatase (APAAP) method. The cases were considered positive for p53 if at least 5% of the tumor cells expressed this protein by immunostaining. Results. There was no significant difference observed between the studied groups in regards to age, sex, Lauren’s classification and tumor differentiation. There was, however, a significant difference observed in the depth of tumor invasion between Barrrett’s adenocarcinoma and adenocarcinoma of the cardia compared with the adenocarcinoma of the antrum. Namely, at the time of surgery, both Barrett’s adenocarcinomas and adenocarcinomas of the cardia, were significantly more advanced comparing with the adenocarcinomas of the antrum. Overexpression of p53 was found in 40% (4/10) of Barrett’s adenocarcinomas, 72% (18/25) of adenocarcinoma of the cardia and 65% (20/31) of adenocarcinoma of the antrum. No significant differences in p53 expression in relation to sex, type (Lauren) of tumor, depth of invasion, lymph node involvement, or tumor differentiation were observed in any of the analyzed groups of tumors. Patients with more advanced Barrett’s adenocarcinoma and in the cases of lymph node invasion revealed tendency for the greater p53 positivity compared with the early forms and lymph node-negative cases; however, this difference was not significant according to the statistical analysis. With regard to adenocarcinoma of the cardia, higher rates of p53 positivity were recorded in poorly differentiated, more advanced cases with lymph node invasion. Nevertheless, none of these differences was statistically significant. On the contrary, in the patients with adenocarcinoma of the antrum, greater p53 positivity was revealed in early forms without lymph node involvement, but the observed difference was not statistically significant. Conclusion. No significant differences in p53 protein expression in terms of sex, type (Lauren) of tumor, depth of invasion, lymph node involvement, or tumor differentiation were observed in any of the analyzed groups of tumors (Barrett’s adenocarcinoma, adenocarcinoma of the cardia and adenocarcinoma of the antrum)

The ACS Virgo Cluster Survey III. Chandra and HST Observations of Low-Mass X-Ray Binaries and Globular Clusters in M87

The ACIS instrument on board the Chandra X-ray Observatory has been used to carry out the first systematic study of low-mass X-ray binaries (LMXBs) in M87. We identify 174 X-ray point-sources, of which ~150 are likely LMXBs. This LMXB catalog is combined with deep F475W and F850LP images taken with ACS on HST to examine the connection between LMXBs and globular clusters in M87. Of the 1688 globular clusters in our catalog, f_X = 3.6 +- 0.5% contain a LMXB and we find that the metal-rich clusters are 3 +- 1 times more likely to harbor a LMXB than their metal-poor counterparts. In agreement with previous findings for other galaxies, we find that brighter, more metal-rich clusters are more likely to contain a LMXB. For the first time, however, we are able to demonstrate that the probability, p_X, that a given cluster will contain a LMXB depends sensitively on the dynamical properties of the host cluster. Specifically, we use the HST images to measure the half-light radius, concentration index and central density, \rho_0, for each globular, and define a parameter, \Gamma, which is related to the tidal capture and binary-neutron star exchange rate. Our preferred form for p_X is then p_X \propto \Gamma \rho_0^{-0.42\pm0.11} (Z/Z_{\odot})^{0.33\pm0.1}. We argue that if the form of p_X is determined by dynamical processes, then the observed metallicity dependence is a consequence of an increased number of neutron stars per unit mass in metal-rich globular clusters. Finally, we find no compelling evidence for a break in the luminosity distribution of resolved X-ray point sources. Instead, the LMXB luminosity function is well described by a power law with an upper cutoff at L_X ~ 10^39 erg/s. (abridged)Comment: 23 pages, 21 figures. Accepted for publication in ApJ. Also available at http://www.physics.rutgers.edu/~pcote/acs/publications.htm

Formation of Galactic Nuclei

We investigate a model in which galactic nuclei form via the coalescence of pre-existing stellar systems containing supermassive black holes. Merger simulations are carried out using N-body algorithms that can follow the formation and decay of a black-hole binary and its effect on the surrounding stars down to sub-parsec scales. Our initial stellar systems have steep central density cusps similar to those in low-luminosity elliptical galaxies. Formation of a black-hole binary transfers energy to the stars and lowers the central density; continued decay of the binary creates a ~1/r density cusp similar to those observed in bright elliptical galaxies, with a break radius that extends well beyond the sphere of gravitational influence of the black holes. The decay of the black hole binary is followed over a factor of ~20 in separation after formation of a hard binary, considerably farther than in previous simulations. We see almost no dependence of the binary's decay rate on number of particles in the simulation, contrary to earlier studies in which a lower initial density of stars led to a more rapid depletion of the binary's loss cone. We nevertheless argue that the decay of a black hole binary in a real galaxy would be expected to stall at separations of 0.01-1 pc unless some additional mechanism is able to extract energy from the binary. Our results support a picture in which the observed dependence of nuclear cusp slope on galaxy luminosity is a consequence of galaxy interactions. We also discuss the implications of our results for the survivability of dark-matter cusps.Comment: 35 pages, 19 postscript figures, uses emulateapj.sty, onecolfloat.st

The ACS Virgo Cluster Survey X. Half-light Radii of Globular Clusters in Early-Type Galaxies: Environmental Dependencies and a Standard Ruler for Distance Estimation

We have measured half-light radii, r_h, for globular clusters (GCs) belonging to the 100 early-type galaxies observed in the ACS Virgo Cluster Survey and the elliptical galaxy NGC 4697. An analysis of the dependencies of the measured r_h on both the properties of the GCs themselves and their host galaxies reveals that the average r_h increases with increasing galactocentric distance or, alternatively, with decreasing galaxy surface brightness. For the first time, we find that the average r_h decreases with the host galaxy color. We also show that there is no evidence for a variation of r_h with the luminosity of the GCs. Finally, we find in agreement with previous observations that the average r_h depends on the color of GCs, with red GCs being ~17% smaller than their blue counterparts. We show that this difference is probably a consequence of an intrinsic mechanism, rather than projection effects, and that it is in good agreement with the mechanism proposed in Jordan (2004). We discuss these findings in light of two simple pictures for the origin of the r_h of GCs and show that both lead to a behavior in rough agreement with the observations. After accounting for the dependencies found we show that the average GC half-light radii can be successfully used as a standard ruler for distance estimation. We outline the methodology, and provide a calibration for its use. We find = 2.7 +- 0.35 pc for GCs with (g-z)=1.2 mag in a galaxy with color (g-z)_{gal}=1.5 mag and at an underlying surface z-band brightness of mu_z = 21 mag arcsec^{-2}. Using this technique, we place an upper limit of 3.4 Mpc on the 1-sigma line-of-sight depth of the Virgo Cluster. Finally, we examine the form of the r_h distribution for our sample galaxies and provide an analytic expression which successfully describes this distribution. (Abridged)Comment: 18 pages, 13 figures. Accepted for publication in ApJ. Also available at http://www.physics.rutgers.edu/~pcote/acs/publications.htm

The ACS Virgo Cluster Survey. VI. Isophotal Analysis and the Structure of Early-Type Galaxies

(Abridged) We present a detailed analysis of the morphology, isophotal parameters and surface brightness profiles for 100 early-type members of the Virgo Cluster, from dwarfs (M_B = -15.1 mag) to giants (M_B = -21.8 mag). Each galaxy has been imaged in two filters, closely resembling the Sloan g and z passbands, using the Advanced Camera for Surveys on board the Hubble Space Telescope. Dust and complex morphological structures are common, with kiloparsec-scale stellar disks, bars, and nuclear stellar disks seen in 60% of galaxies with intermediate luminosity (-20 < M_B < -17), and dust seen in 42% of galaxies brighter than M_B = -18.9 mag. Dust morphologies range from faint wisps and patches on tens of parsec scales, to regular, highly organized kpc-scale dust disks, often showing evidence of recent star formation. Surface brightness profiles and isophotal parameters are derived typically within 8 kpc from the center for the brightest galaxies, and 1.5 kpc for the faintest systems, with a resolution (FWHM) of 7 pc. Based on a parametrization of the surface brightness profiles in terms of a Sersic or core-Sersic model, we find that 1) there is no evidence of a bimodal behavior of the slope, gamma, of the profile in the innermost regions; 2) although the brightest galaxies have shallow inner profiles, the shallowest profiles (lowest gamma values) are found in faint dwarf systems; 3) the widely adopted separation of early-type galaxies between "core" and "power-law" types, which had originally been prompted by the claim of a clear bimodal distribution of gamma values, is untenable; and 4) there is no evidence of a structural dichothomy between dwarf and regular ellipticals.Comment: Accepted by The Astrophysical Journal Supplement Series. This submission contains low resolution figures; we strongly recommend downloading the original version of the paper from the ACSVCS project website: http://www.cadc.hia.nrc.gc.ca/community/ACSVCS/publications.html#acsvcs

The problems associated with the treatment of chronic hyperuricaemia in Serbia

Gout is a direct consequence of chronic hyperuricaemia, who 's prevalence is following sedentary lifestyle and improper diet dominated by foods rich in purines and non-alcoholic and alcoholic beverages with sweeteners. Since gout is associated with other serious comorbidities is essential that the treatment of this disease would be adequate. The results of numerous studies indicate that the worldwide therapy of gout is insufficient in most patients. There is no doubt that this assessment is true for the treatment of gout in the Republic of Serbia, and the reasons for such an assessment are numerous. The most important reason is related to the choice of drugs, because in Serbia they are only available xanthine oxidase inhibitors, which reduce the formation of uric acid, while drugs that increase the excretion of uric acid-Uricosuric drugs are not registered. Beside uricosurics, in Serbia is not registered neither colhicine, a drug that has a very important role in the prevention of adverse effects of antihyperuricaemia drugs in the first few weeks of treatment

The problems associated with the treatment of chronic hyperuricaemia in Serbia

Gout is a direct consequence of chronic hyperuricaemia, who's prevalence is following sedentary lifestyle and improper diet dominated by foods rich in purines and non-alcoholic and alcoholic beverages with sweeteners. Since gout is associated with other serious comorbidities is essential that the treatment of this disease would be adequate. The results of numerous studies indicate that the worldwide therapy of gout is insufficient in most patients. There is no doubt that this assessment is true for the treatment of gout in the Republic of Serbia, and the reasons for such an assessment are numerous. The most important reason is related to the choice of drugs, because in Serbia they are only available xanthine oxidase inhibitors, which reduce the formation of uric acid, while drugs that increase the excretion of uric acid- Uricosuric drugs are not registered. Beside uricosurics, in Serbia is not registered neither colhicine, a drug that has a very important role in the prevention of adverse effects of antihyperuricaemia drugs in the first few weeks of treatment