On the possibility of a warped disc origin of the inclined stellar discs at the Galactic Centre

(Abridged) The Galactic Center (GC) hosts a population of young stars some of which seem to form mutually inclined discs of clockwise and counter clockwise rotating stars. We present a warped disc origin scenario for these stars assuming that an initially flat accretion disc becomes warped due to the Pringle instability, or due to Bardeen-Petterson effect, before it fragments to stars. We show that this is plausible if the star formation efficiency $\epsilon_{SF} \lesssim 1$, and the viscosity parameter $\alpha \sim 0.1$. After fragmentation, we model the disc as a collection of concentric, circular, mutually tilted rings, and construct warped disc models for mass ratios and other parameters relevant to the GC environment, but also for more massive discs. We take into account the disc's self-gravity and the torques exerted by a surrounding star cluster. We show that a self-gravitating low-mass disc ($M_d / M_{bh} \sim 0.001$) precesses in integrity in the life-time of the stars, but precesses freely when the torques from a non-spherical cluster are included. An intermediate-mass disc ($M_d / M_{bh} \sim 0.01$) breaks into pieces which precess independently in the self-gravity-only case, and become disrupted in the presence of the star cluster torques. For a high-mass disc ($M_d / M_{bh} \sim 0.1$) the evolution is dominated by self-gravity and the disc is broken but not dissolved. The time-scale after which the disc breaks scales almost linearly with ($M_d / M_{bh}$) for self-gravitating models. Typical values are longer than the age of the stars for a low mass disc, and are in the range $\sim 8 \times 10^4-10^5$ yr for high and intermediate-mass discs respectively. None of these models explain the rotation properties of the two GC discs, but a comparison of them with the clockwise disc shows that the lowest mass model in a spherical star cluster matches the data best.Comment: 16 pages, 19 figures, abstract abridged to meet arXiv requirements. Accepted for publication in MNRA

Semih Balcıoğlu, karikatürde 50.yılını kutluyor

Taha Toros Arşivi, Dosya No: 15-Semih BalcıoğluUnutma İstanbul projesi İstanbul Kalkınma Ajansı'nın 2016 yılı "Yenilikçi ve Yaratıcı İstanbul Mali Destek Programı" kapsamında desteklenmiştir. Proje No: TR10/16/YNY/010

The effect of aging on semen parameters in normozoospermic men: A cross-sectional study

Background: Semen parameters change with age and are reported differently worldwide. Objective: This retrospective cross-sectional study aimed to investigate the semen quality pattern among aging men and the age thresholds for semen parameters. Materials and Methods: The records of men who had normal semen parameters from January 2015-June 2020 were retrospectively evaluated for andrological outpatient at Samsun Training and Research hospital and Gazi hospital in Samsun, Turkey. Adult men meeting the inclusion criteria were divided into 3 groups of I) 18-29 yr (n = 629), II) 30-39 yr (n = 775), and III) 40-49 yr (n = 190). Correlations between age and sperm parameters were then analyzed. Results: A total of 1594 men were enrolled in the study. Significant differences were observed in total sperm numbers, total motility rates, progressive motility rates, nonprogressive motility rates, normal morphology rates, mean semen volume, and sperm concentrations. The parameters of total sperm number, progressive motility rate, and normal morphology rate were significantly higher in group I than in the other 2 groups (p < 0.001, p < 0.001, and p < 0.001, respectively) and in group II compared to group III (p = 0.001, p = 0.003, and p < 0.001), respectively. Mean semen volume and total motility rate were significantly higher in group I than in the other groups (p = 0.001 and p < 0.001, respectively). However, no difference was observed between group II and group III (p = 0.61 and p = 0.04, respectively). Conclusion: Age has a significant impact on semen parameters capable of affecting male fertility, particularly total sperm numbers, the progressive motility rate, and the normal morphology rate. Key words: Age, Fertility, Semen, Semen quality

Carbon Nanotube-Conducting Polymer Composites as Electrode Material in Electroanalytical Applications

This chapter gives a brief overview of the preparation, characterization, and analytical applications for combinations of polymers and carbon nanotubes (CNTs) that have been prepared in different ways, which are used as an electrode material. For this purpose, multiwalled or single-walled CNTs are composed of different types of conductive polymers. The preparation of CNT-conducting polymer composite electrodes was explained by their deposition order. Chemical and morphological surface characterizations of composite electrodes were presented by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. In addition, CNT-based polymer composite electrode usage in sensor applications for trace organic/inorganic compounds and energy applications is discussed in the last part of this chapter

Effects of peripheral neuropathy on exercise capacity and quality of life in patients with chronic obstructive pulmonary diseases

Introduction: Chronic obstructive pulmonary diseases (COPD) have some systemic effects including systemic inflammation, nutritional abnormalities, skeletal muscle dysfunction, and cardiovascular, skeletal and neurological disorders. Some studies have reported the presence of peripheral neuropathy (PNP) at an incidence of 28-94% in patients with COPD. Our study aimed to identify whether PNP affects exercise performance and quality of life in COPD patients. Material and methods: Thirty mild-very severe patients with COPD (male/female = 29/1, mean age = 64 +/- 10 years) and 14 normal subjects (male/female = 11/5, mean age = 61 +/- 8 years) were included in the present study. All subjects underwent pulmonary function testing (PFT), cardiopulmonary exercise testing, electroneuromyography and short form 36 (SF-36). Results: Peak oxygen uptake (PeakVO(2)) was lower in COPD patients (115 +/- 0.53 l/min) than healthy subjects (2.02 +/- 0.46 l/min) (p = 0.0001). There was no PUP in healthy subjects while 16 (53%) of the COPD patients had PNP. Forced expiratory volume in 1 s (FEV1) and PeakVO(2) were significantly different between patients with PNP and those without (p = 0.009, p = 0.03 respectively). Quality of life of patients with PNP was lower than that of patients without PNP (p < 0.05). Conclusions: The present study demonstrates the exercise limitation in COPD patients with PUP Thus, presence of PNP has a poor effect on exercise capacity and quality of life in patients with COPD. Furthermore, treatment modalities for PNP can be recommended to these patients in order to improve exercise capacity and quality of life.Wo

Risk of HSIL (CIN 2-3) on colposcopic biopsy is minimal in postmenopausal women with LSIL on cytology and a negative HRHPV test

BackgroundCurrent cervical cancer screening guidelines recommend a 1-year follow-up period for patients with a postmenopausal low-grade squamous intraepithelial lesion (LSIL) who are test negative for high-risk human papillomavirus (HrHPV). The aim of this study was to assess whether such patients had an increased immediate risk of high-grade squamous intraepithelial lesion. MethodsWe assessed 54 HrHPV-negative women with postmenopausal LSIL in the Department of Obstetrics and Gynecology of our hospital between 2012 and 2013. All patients underwent liquid-based cytology and reflex HrHPV testing (for human papillomavirus [HPV] types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68). Colposcopic examination and guided biopsy were performed by the same gynecologist (MO). ResultsThe average age of the patients was 53.13.2 years. There were 33 patients (61%) with cervical intraepithelial neoplasia (CIN) grade 1 and 21 who were non-dysplastic. None of the patients was positive for CIN 2 or any other lesions. ConclusionsIf the HPV test is negative, repeat cytology after 12 months is recommended by the American Society for Colposcopy and Cervical Pathology for cases of HrHPV-negative postmenopausal LSIL. We recommend reflex HPV testing as the best choice for patients who test positive for postmenopausal LSIL by Pap smear, in line with the literature. Diagn. Cytopathol. 2016;44:969-974. (c) 2016 Wiley Periodicals, Inc

Accretion disk warping by resonant relaxation: The case of maser disk NGC4258

The maser disk around the massive black hole (MBH) in active galaxy NGC 4258 exhibits an O(10 deg) warp on the O(0.1 pc) scale. The physics driving the warp are still debated. Suggested mechanisms include torquing by relativistic frame dragging or by radiation pressure. We propose here a new warping mechanism: resonant torquing of the disk by stars in the dense cusp around the MBH. We show that resonant torquing can induce such a warp over a wide range of observed and deduced physical parameters of the maser disk.Comment: 4 pp, 2 figure

Echocardiographic evaluation of diastolic functions in patients with polycystic ovary syndrome: A comperative study of diastolic functions in sub-phenotypes of polycystic ovary syndrome

Background: Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine disorder among reproductive-aged women. It is known to be associated with cardiovascular diseases. The aim of this study was to determine and compare the echocardiographic data of patients according to the phenotypes of PCOS. Methods: This study included 113 patients with PCOS and 52 controls. Patients were classified into four potential PCOS phenotypes. Laboratory analyses and echocardiographic measurements were performed. Left ventricular mass was calculated by using Devereux formula and was indexed to body surface area. Results: Phenotype-1 PCOS patients had significantly higher homeostasis model assessment — insu­lin resistance (HOMA-IR) (p = 0.023), free testosterone (p &lt; 0.001), LDL cholesterol levels (p &lt; 0.001) and free androgen index (p &lt; 0.001) compared with the control group. There were significant differences between groups regarding the septal thickness, posterior wall thickness, Left ventricular ejection frac­tion, E/A ratio and left ventricular mass index (for all, p &lt; 0.05). PCOS patients with phenotype 1 and 2 had significantly higher left ventricular mass index than the control group (p &lt; 0.001). In univariate and multivariate analyses, PCOS phenotype, modified Ferriman-Gallwey Score and estradiol were found as variables, which independently could affect the left ventricular mass index. Conclusions: This study showed that women in their twenties who specifically fulfilled criteria for PCOS phenotype-1 according to the Rotterdam criteria, had higher left ventricular mass index and decreased E/A ratio, which might be suggestive of early stage diastolic dysfunction. (Cariol J 2017; 24, 4: 364–373