Supermassive black hole formation during the assembly of pre-galactic discs

In this paper we discuss the evolution of gravitationally unstable pre-galactic discs that result from the collapse of haloes at high redshift $z \approx 10$ or so, which have not yet been enriched by metals. In cases where molecular hydrogen formation is suppressed the discs are maintained at a temperature of a few thousand degrees Kelvin. However, when molecular hydrogen is present cooling can proceed down to a few hundred degrees Kelvin. Analogous to the case of the larger scale proto-galactic discs, we assume that the evolution of these discs is mainly driven by angular momentum redistribution induced by the development of gravitational instabilities in the disc. We also properly take into account the possibility of disc fragmentation. We thus show that this simple model naturally predicts the formation of supermassive black holes in the nuclei of such discs and provides a robust determination of their mass distribution as a function of halo properties. We estimate that roughly 5% of discs resulting from the collapse of haloes with $M\approx 10^7 M_{\odot}$ should host a massive black hole with a mass $M_{\rm BH}\approx 10^5 M_{\odot}$. We confirm our arguments with time-dependent calculations of the evolution of the surface density and of the accretion rate in these primordial discs. This mechanism offers an efficient way to form seed black holes at high redshift. The predicted masses for our black hole seeds enable the comfortable assembly of $10^9 M_{\odot}$ black holes powering the luminous quasars detected by the Sloan Digital Sky Survey at $z = 6$ for a concordance cosmology. (abridged)Comment: 12 pages, 8 figures, submitted to MNRA

The Gamma Ray Burst Luminosity Function in the Light of the Swift 2-year Data

We compute the luminosity function (LF) and the formation rate of long gamma ray bursts (GRBs) by fitting the observed differential peak flux distribution obtained by the BATSE satellite in three different scenarios: i) GRBs follow the cosmic star formation and their LF is constant in time; ii) GRBs follow the cosmic star formation but the LF varies with redshift; iii) GRBs form preferentially in low-metallicity environments. We find that the differential peak flux number counts obtained by BATSE and by Swift can be reproduced using the same LF and GRB formation rate, indicating that the two satellites are observing the same GRB population. We then check the resulting redshift distributions in the light of Swift 2-year data, focusing in particular on the relatively large sample of GRBs detected at z>2.5. We show that models in which GRBs trace the cosmic star formation and are described by a constant LF are ruled out by the number of high-z Swift detections. This conclusion does not depend on the redshift distribution of bursts that lack of optical identification, nor on the existence of a decline in star formation rate at z>2, nor on the adopted faint-end of the GRB LF. Swift observations can be explained by assuming that the LF varies with redshift and/or that GRB formation is limited to low-metallicity environments.Comment: 7 pages, 3 figures, ApJ Letter in pres

STUDY ON ANXIETY LEVEL AMONG SCHOOL STUDENTS UNDERGOING HIGHER SECONDARY EXAMINATION

Today anxiety is a common phenomenon of everyday life. It plays a crucial role in human life because all of us are victim of anxiety in different ways (Goodstein and Lanyon, 1975). The aim of this study was to assess the stress level of academic among the higher secondary school students. Sampling technique that was used for the selection of the sample in this case was convenience sampling based on inclusion and exclusion criteria with the sample size was 150. The research instruments are questionnaire method. Collected data were statistically analyzed through descriptive statistics and inferential statistics and also findings could be useful for the students to know their level of anxiety and they can take up necessary and sufficient practices to reduce their anxiety

A STUDY TO ASSESS THE LEVEL OF DEPRESSION IN PATIENTS WITH HIV INFECTION BY USING MODIFIED BECK DEPRESSION INVENTORY AT NAMAKKA

AIDS is the most significant threat to the human race in the modern era. In 2013, the world registered 2.3 million new HIV infections, and while in some countries the number of people living with HIV is actually increasing, this can be taken as a good sign. The aim of this study was to assess the level of depression among HIV Patients. Sampling technique that was used for the selection of the sample in this case was convenience sampling based on inclusion and exclusion criteria with the sample size was 50. The research instruments are questionnaire method. Collected data were statistically analyzed through descriptive statistics and inferential statistics and also findings could be useful for the Patients to know their level of depression and they can take up necessary and sufficient practices to reduce their level of depression

The sizes of galaxy halos in galaxy cluster Abell 1689

The multiple images observed in galaxy cluster Abell 1689 provide strong constraints not only on the mass distribution of the cluster but also on the ensemble properties of the cluster galaxies. Using parametric strong lensing models for the cluster, and by assuming well motivated scaling laws between the truncation radius s and the velocity dispersion sigma of a cluster galaxy we are able to derive sizes of the dark matter halos of cluster galaxies. For the scaling law expected for galaxies in the cluster environment (s propto sigma), we obtain s = 64^{+15}_{-14} (sigma / 220 km/s) kpc. For the scaling law used for galaxies in the field with s propto sigma^2 we find s = 66^{+18}_{-16} (sigma / 220 km/s)^2 kpc. Compared to halos of field galaxies, the cluster galaxy halos in Abell 1689 are strongly truncated.Comment: 12 pages, 4 figures. Accepted for publication in the Ap

Gestational hyperglycemia on diet and medication: impact on placental pathology and pregnancy outcomes

Background: To evaluate the placental morphology and perinatal outcome in patients with gestational hyperglycemia on diet and medication.Methods: Placental examinations performed at the Department of Pathology between August 2016 to August 2018 were retrospectively reviewed. Of the received 140 placentas, 35 of gestational diabetes (GDM) and pre gestational diabetes were identified and segregated into hyperglycemia on diet and on medication. The clinical details, placental findings and perinatal outcome of patients in both the groups (gestational hyperglycemia on diet and medication) were collected and analyzed.Results: Among the 35 cases, there were 24 cases of mild gestational hyperglycemia controlled with diet and 11 cases of hyperglycemia on medication (oral hypoglycemic drugs ± insulin).Most of the placentae in both the groups weighed less than tenth centile. The cord abnormalities such as hyper coiling, velamentous /marginal insertion and furcate cord were observed more in women with GDM on diet. There was no significant gross placental lesion in those on medication. Placental histological features most consistently associated with both the groups include, disturbances of villous maturation (DVM), Derangements in uteroplacental / foetoplacental circulation and villous capillary lesions. Small for gestational age and intrauterine foetal death were found in both the groups, but more commonly in patients with hyperglycemia on medication.Conclusions: Villous maturation defects, uteroplacental / foetoplacental malperfusion are the essential placental changes which can result in adverse perinatal outcomes in women with hyperglycemia irrespective of the diabetic control

Gasotransmitters: a review

The gaseous molecules produced endogenously with several physiological functions are called gasotransmitters. Even though initially, they were predominantly thought to be of neuronal origin, recent research has clarified that they have roles far beyond that. Their primary function is maintaining the integrity of the cardiovascular system and many other parts. From the available knowledge, we have just started to learn about their roles in physiological systems that could be translated to pharmacological drug development and therapeutics. Most of the process that remains in the form of preclinical research has to go a long way toward utilizing them in therapeutics. This review addresses the various levels at which they could be potentially exploited as therapeutics and their recent entry into clinical trials