On the Origin of Metal-poor Stars in the Solar Neighborhood

We determined the ages, the kinematic parameters and Galactic orbital parameters of six metal-poor (-2.4<[Fe/H]<-1 dex) F-type high proper motion (HPM) stars to investigate their HPM nature and origin. For the kinematical procedure, the astrometric data from the Gaia DR2 was used. High resolution ELODIE spectra of the six dwarfs were also used to obtain accurate [Fe/H] abundances and up-to-date [$\alpha$/Fe] abundances. The calculations for stellar ages were based on Bayesian statistics, with the computed ages falling in the range 9.5-10.1 Gyrs. On the basis of the metallicities and ages, six HMP stars are members of halo (HD6755, HD84937, BD +42 3607) or members of the low-metallicity tail of the thick disk (HD 3567, HD 194598, HD 201891). However, Galactic orbital parameters suggest thin disk (HD 84937, HD 194598), thick disk (HD 3567, HD 201891), and halo (HD 6755, BD +42 3607) population. The dynamical analysis was also performed for the escape scenario from the candidate GCs. The tidal disruption of a dwarf galaxy was also considered to be as an alternative origin. HD 6755, HD 194598, and HD 3567 with their retrograde orbital motions are likely candidate stars for a tidally disrupted dwarf galaxy origin. However, HD 194598 relationship with NGC 6284 presents an interesting case. Its encounter velocity is low (16+/-28 km/s) and their ages and metallicities are very nearly consistent with each other at the 1$\sigma$ level. The rest of the HPM sample stars have a 4% to 18% probability of encountering with selected GCs for 1.5 tidal radii. This indicates that a globular cluster origin for the program stars is unlikely.Comment: 50 pages, including 13 figures and 16 tables, accepted for publication in Ap

Population types of cataclysmic variables in the solar neighborhood

The Galactic orbital parameters of 159 cataclysmic variables in the Solar neighbourhood are calculated, for the first time, to determine their population types using published kinematical parameters. Population analysis shows that about 6 per cent of cataclysmic variables in the sample are members of the thi ck disc component of the Galaxy. This value is consistent with the fraction obt ained from star count analysis. The rest of the systems in the sample are found to be in the thin disc component of the Galaxy. Our analysis revealed no halo CVs in the Solar vicinity. About 60 per cent of the thick disc CVs have orbital periods be low the orbital period gap. This result is roughly consistent with the predictions of population synthesis models developed for cataclysmic variables. A kinematical age of 13 Gyr is obtained using total space velocity dispersion of the most probable thick disc CVs which is consistent with the age of thick disc component of the Galaxy

Increased serum procalcitonin levels in pregnant patients with asymptomatic bacteriuria

Background: Among the pregnancy urinary tract infections, asymptomatic bacteriuria (ASB) is the most common one. Untreated ASB can progress to pyelonephritis in 30-50% of the patients and can also result in prematurity in 27% of the pregnancy so it needs immediate diagnosis and treatment. In this study, we wanted to evaluate procalcitonin levels, compared to other inflammatory in pregnant women with ASB.Methods: The study was designed between the period of January 2012 and February 2013 at Sakarya University School of Medicine, Department of Gynecology and Obstetrics. The study population included 30 pregnant patients with asymptomatic bacteriuria and 39 healthy pregnant controls.Results: Mean age was 28 (SD, 5.5) of the study population; mean maternal weight was 70 (SD, 8) kilogram. There were no statically significant differences between the groups according to the routine biochemical parameters, but gestational age was significantly lower in the ASB group compared to the controls (20.4 vs 28.6, respectively; p 0.05 ng/ml and 21(70%) patients had negative procalcitonin levels (Chi-squrae, p < 0.001). The sensitivity and specificity of procalcitonin assay for ASB was calculated as 30% and 100%, respectively. The positive predictive value was 100% and the negative predictive value was 65%. The most frequent microorganisms in the urine culture were Escherichia coli (26 patients, 87%), Proteus mirabilis (3 patients, 10%) and Klebsiella (1 patient, 3%) in the ASB group. We experienced four (44%) recurrences among nine positive procalcitonin in ASB patients after completion of treatment of the first ASB diagnosis.Discussion: Procalcitonin levels were significantly higher in ASB group than the control group and serum procalcitonin levels were higher in pregnant women with recurrent ASB. This finding is an important result revealed that high procalcitonin level can predict the further urinary tract infection risk. Finally, serum procalcitonin levels were normal in healthy pregnant women while other inflammatory markers such as WBC, ESR and CRP levels were higher. © 2013 Bilir et al.; licensee BioMed Central Ltd

LAMİNER BORU AKIŞINDA HIZ DAĞILIMININ GEÇİCİ REJİM BİRLEŞİK ISI TRANSFERİNE ETKİSİ

Transient conjugated heat transfer in laminar pipe flow is analysed involving two-dimensional wall and fluid axial conduction. The problem is solved numerically by a finite difference method for a semi-infinite pipe which is initially isothermal and both for hydrodynamically developing and developed flow with a sudden change in the ambient temperature. Heat transfer characteristics of the flow are found to be sensitive to the velocity profile. The results are given by non-dimensional interfacial heat flux values, the outer and inner wall temperatures, bulk temperatures, radial distributions of the fluid temperatures and Nusselt numbers. In order to illustrate the effects of the velocity profile, the results for the developing flow and for the parabolic velocity profile are plotted as comparative.Borularda laminer akış, geçici rejim birleşik ısı transferi, iki boyutlu cidar ve eksenel akışkan iletimi dikkate alınarak incelenmiştir. Problem, başlangıçta eşit sıcaklıktaki yarı sonsuz bir boruda, hem hidrodinamik olarak gelişmekte olan hem de gelişmiş akış için, çevre akışkanı sıcaklığındaki ani değişme şartı ile ele alınmış ve sonlu farklar yöntemi ile sayısal olarak çözülmüştür. Hız profilinin ısı transferi karakteristikleri üzerinde etkili olduğu gözlenmiş, sonuçlar boyutsuz yerel arayüzey ısı akısı, dış yüzey ve arayüzey sıcaklıkları, yığık sıcaklıklar, radyal yönde sıcaklık değişimi ve Nusselt sayıları cinsinden verilmiştir. Hız profilinin ısı transferi karakteristikleri üzerindeki etkilerini belirleyebilmek için, sonuçlar parabolik ve gelişmekte olan hız dağılımı için karşılaştırmalı olarak verilmiştir

A Detailed Archival CHANDRA Study of the Young Core-collapse Supernova Remnant 1E 0102.2-7219 in the Small Magellanic Cloud

We present an archival Chandra study of the O-rich supernova remnant (SNR) 1E 0102.2-7219 in the Small Magellanic Cloud. Based on deep similar to 265 ks archival Chandra data, we performed a detailed spatially resolved spectral analysis of 1E 0102.2-7219. Our aim is to reveal the spatial and chemical structures of this remnant in unprecedented detail. Radial profiles of O, Ne, and Mg abundances based on our analysis of regional spectra extracted along nine different azimuthal directions of 1E 0102.2-7219 suggest the contact discontinuity at similar to 5.5 pc from the geometric center of the X-ray emission of the SNR. We find that the metal-rich ejecta gas extends further outward to the west and southwest than in the other directions of the SNR. The average O/Ne, O/Mg, and Ne/Mg abundance ratios of the ejecta are in plausible agreement with the nucleosynthesis products from the explosion of a similar to 40 M-circle dot progenitor. We estimate an upper limit on the Sedov age of similar to 3500 yr and explosion energy of similar to 1.8 x 10(51) erg for 1E 0102.2-7219. We discuss the implications of our results for the geometrical structure of the remnant, its circumstellar medium and the nature of the progenitor star. Our results do not fit with a simple picture of the reverse-shocked emission from a spherical shell-like ejecta gas with a uniformly distributed metal abundance and a power-law density along the radius of the SNR

A new ranking scheme for the institutional scientific performance

We propose a new performance indicator to evaluate the productivity of research institutions by their disseminated scientific papers. The new quality measure includes two principle components: The normalized impact factor (IF) of the journal in which paper was published, and the number of citations received per year since it was published. In both components, the scientific impacts are weighted by the contribution of authors from the evaluated institution. As a whole, our new metric, namely, the Institutional Performance Score (IPS) takes into account both journal based impact and articles specific impacts. We apply this new scheme to evaluate research output performance of Turkish institutions specialized in astronomy and astrophysics in the period of 1998-2012. We discuss the implications of the new metric, and emphasize the benefits of it along with a comparison to other proposed institutional performance indicators. This study contains a new bibliometric indicator were developed to measure the scientific research performance of the institutions

Kepler Binary Stars in the NGC 6819 Open Cluster: KIC 5113146 and KIC 5111815

In this study, an investigation of two double-lined binary stars KIC 5113146 and KIC 5111815 in the NGC 6819 open cluster is presented based on both photometric and spectroscopic data. Simultaneous analysis of light and radial velocity curves was made and the absolute parameters of the systems' components were determined for the first time. We find that both systems have F-type main-sequence components. The masses and radii were found to be M-1 = 1.29 +/- 0.02M(circle dot), R-1 = 1.47 +/- 0.03 R-circle dot and M-2 = 1.19 +/- 0.02 M-circle dot, R-2 = 1.13 +/- 0.02 R-circle dot for the primary and secondary components of KIC 5113146; and M-1 = 1.51 +/- 0.08 M-circle dot, R-1 = 2.02 +/- 0.05 R-circle dot and M-2 = 1.19 +/- 0.07 M-circle dot, R-2 = 1.32 +/- 0.04 R-circle dot for the components of KIC 5111815, respectively. The evolutionary status of the components was evaluated based on the MESA evolutionary tracks and isochrones. The ages of KIC 5111815 and KIC 5113146 were derived to be about 2.50 +/- 0.35 Gyr and 1.95 +/- 0.40 Gyr, respectively. Photometric distances were calculated to be 2850 +/- 185 pc for KIC 5113146 and 3120 +/- 260 pc for KIC 5111815. The results reveal that both KIC 5113146 and KIC 5111815 systems are the most likely members of NGC 6819

A new ranking scheme for the institutional scientific performance

We propose a new performance indicator to evaluate the productivity of research institutions by their disseminated scientific papers. The new quality measure includes two principle components: The normalized impact factor (IF) of the journal in which paper was published, and the number of citations received per year since it was published. In both components, the scientific impacts are weighted by the contribution of authors from the evaluated institution. As a whole, our new metric, namely, the Institutional Performance Score (IPS) takes into account both journal based impact and articles specific impacts. We apply this new scheme to evaluate research output performance of Turkish institutions specialized in astronomy and astrophysics in the period of 1998–2012. We discuss the implications of the new metric, and emphasize the benefits of it along with a comparison to other proposed institutional performance indicators. This study contains a new bibliometric indicator were developed to measure the scientific research performance of the institutions

Vertical and radial metallicity gradients in high latitude galactic fields with SDSS

We used the ugr magnitudes of 1437467 F-G type main-sequence stars with metal abundance -2 5 kpc) in three galactocentric distance intervals, 6 < R <= 10, 10 < R <= 15 and 15 < R <= 20 kpc. The first one corresponding to the interval 6 < R <= 10 kpc is equal to d[Fe/H]/dz = -0.023 +/- 0.006 dex kpc(-1), while the others at larger galactocentric distances are close to zero. We derived synthetic vertical metallicity gradients for 2,230,167 stars and compared them with the observed ones. There is a good agreement between the two sets of vertical metallicity gradients for the thin disc, while they are different for the thick disc. For the halo, the conspicuous difference corresponds to the galactocentric distance interval 6 < R <= 10 kpc, while they are compatible at higher galactocentric distance intervals (C) 2018 COSPAR. Published by Elsevier Ltd. All rights reserved