Properties of Gamma-Ray Burst Progenitor Stars

We determine some basic properties of stars that produce spectacular gamma-ray bursts at the end of their life. We assume that accretion of the outer portion of the stellar core by a central black hole fuels the prompt emission, and that fall-back and accretion of the stellar envelope later produces the plateau in the X-ray light curve seen in some bursts. Using X-ray data for three bursts we estimate the radius of the stellar core to be ~ 1-3 x 10^10 cm, and that of the stellar envelope to be ~ 1-2 x 10^11 cm. The density profile in the envelope is fairly shallow, with \rho ~ r^-2. The rotation speeds of the core and envelope are ~ 0.05 and ~ 0.2 of the local Keplerian speed, respectively.Comment: Science in pres

An Experimental and Analytical Approach to Understanding the Dynamic Leaching from Municipal Solid Waste Combustion Residue

This paper describes an experimental technique involving the use of small columns for generating significant quantities of leachate data from municipal solid waste (MSW) solid residues within a relatively short amount of time. Data analysis using the discretized mass balance equations descriptive of the system results in best estimates of governing transport parameters that can, in turn, be used to predict the long-term release of leachable components (As, Cd, Cu, Fe, Ni, Pb, Zn, Ca, Mg, Na, K, Cl, SO4) from the solid matrix. Results indicate that both chemical solubility and physical transport are important factors affecting the flux of contaminants from the solid to the solution phase

Study of drug prescriptions in medical in-patients in a teaching hospital

Background: Study of prescriptions reveals the drug utilization pattern in a given hospital at a given time. This study was conducted to observe and analyse the prescribing pattern of drugs for the in-patients in the general medicine department of a teaching hospital.Methods: In a prospective observational study, a total of 234 prescriptions of in-patients of general medicine department of a teaching hospital were analysed. The drugs prescribed their route of administration, diagnosis and demographic data were recorded.Results: Pantoprazole and ondansetron were found in most of the prescriptions. Antimicrobials were the commonest class of drugs prescribed. Cephalosporins, metronidazole, doxycycline, ofloxacin and amoxicillin+clavulanate accounted for most of the antimicrobials. A drug prescribed from the national list of essential medicines (NLEM) was 75.97%. Only 3% of the drugs were prescribed by generic names.Conclusions: Prescription of pantoprazole and ondansetron was very frequent in this study. Antimicrobials were found in most of the prescriptions. All the prescriptions in this study had injectable drugs. Three-fourths of the drugs were from the national list of essential medicines (NLEM). Generic drugs need to be prescribed more

The effect of manganese oxide on the sinterability of hydroxyapatite

The sinterability of manganese oxide (MnO2) doped hydroxyapatite (HA) ranging from 0.05 to 1 wt% was investigated. Green samples were prepared and sintered in air at temperatures ranging from 1000 to 1400 °C. Sintered bodies were characterized to determine the phase stability, grain size, bulk density, hardness, fracture toughness and Young's modulus. XRD analysis revealed that the HA phase stability was not disrupted throughout the sintering regime employed. In general, samples containing less than 0.5 wt% MnO2 and when sintered at lower temperatures exhibited higher mechanical properties than the undoped HA. The study revealed that all the MnO2-doped HA achieved >99% relative density when sintered at 1100–1250 °C as compared to the undoped HA which could only attained highest value of 98.9% at 1150 °C. The addition of 0.05 wt% MnO2 was found to be most beneficial as the samples exhibited the highest hardness of 7.58 GPa and fracture toughness of 1.65 MPam1/2 as compared to 5.72 GPa and 1.22 MPam1/2 for the undoped HA when sintered at 1000 °C. Additionally, it was found that the MnO2-doped samples attained E values above 110 GPa when sintered at temperature as low as 1000 °C if compared to 1050 °C for the undoped HA

On the polar decomposition of right linear operators in quaternionic Hilbert spaces

In this article we prove the existence of the polar decomposition for densely defined closed right linear operators in quaternionic Hilbert spaces: If $T$ is a densely defined closed right linear operator in a quaternionic Hilbert space $H$, then there exists a partial isometry $U_{0}$ such that $T = U_{0}|T|$. In fact $U_{0}$ is unique if $N(U_{0}) = N(T)$. In particular, if $H$ is separable and $U$ is a partial isometry with $T = U|T|$, then we prove that $U = U_{0}$ if and only if either $N(T) = \{0\}$ or $R(T)^{\bot} = \{0\}$.Comment: 17 page

Models of Galaxy Clusters with Thermal Conduction

We present a simple model of hot gas in galaxy clusters, assuming hydrostatic equilibrium and energy balance between radiative cooling and thermal conduction. For five clusters, A1795, A1835, A2199, A2390 and RXJ1347.5-1145, the model gives a good description of the observed radial profiles of electron density and temperature, provided we take the thermal conductivity $\kappa$ to be about 30% of the Spitzer conductivity. Since the required $\kappa$ is consistent with the recent theoretical estimate of Narayan & Medvedev (2001) for a turbulent magnetized plasma, we consider a conduction-based equilibrium model to be viable for these clusters. We further show that the hot gas is thermally stable because of the presence of conduction. For five other clusters, A2052, A2597, Hydra A, Ser 159-03 and 3C295, the model requires unphysically large values of $\kappa$ to fit the data. These clusters must have some additional source of heat, most likely an active galactic nucleus since all the clusters have strong radio galaxies at their centers. We suggest that thermal conduction, though not dominant in these clusters, may nevertheless play a significant role by preventing the gas from becoming thermally unstable.Comment: Published in ApJ; 22 pages, including 2 tables, 4 figures; typos corrected to match the published versio

A retrospective study of adverse drug reactions in a tertiary care center

Background: Adverse drug reactions (ADRs) are a major concern in clinical practice. Reporting of ADRs either through health care professionals or the patients themselves is of utmost importance to give an accurate estimate of the prevalence, severity and preventability of ADRs. Present study was conducted to evaluate the prevalence of adverse drug reactions in a tertiary care hospital in Hubballi, Karnataka, India.Methods: This was a retrospective observational study, extending over 6 months (May 2019 to October 2019). A total of 124 cases comprising patients of either sex and age group ranging from 1month to 72 years were studied. The data was collected using CDSCO ADR reporting form. “Naranjo’s Assessment Scale” was used for causality assessment and severity assessment was done in accordance with “Hartwig and Siegel scale”.Results: The study showed majority of ADRs were from General Medicine department and affected skin and appendages (59%). Skin rashes 44 (31.7%) were found to be the most commonly reported ADRs most of them were with antimicrobials 67 (54%).  After causality assessment 83 (66.9%) of the cases were classified as probable and 41 (33.1%) were classified as possible. Majority of serious ADRs were not preventable in our study.Conclusions: ADRs are a major cause of morbidity worldwide. Frequency of ADRs can be reduced by careful follow up and a robust hospital-based pharmacovigilance setup. Measures to improve detection and reporting of adverse drug reactions by all health care professionals is recommended

Prevalence of HIV Infection among Trauma Patients Admitted to\ud Bugando Medical Centre, Mwanza, Tanzania and its\ud Influence on Outcome

HIV infection, a major health problem worldwide, has been reported to be prevalent in trauma patients, thus presents an occupational hazard to health care workers who care for these patients. The purpose of this study was to establish the prevalence of HIV among trauma patients in our setting and to compare the outcome of these patients who are HIV positive with those who are HIV negative. This was a descriptive cross sectional study involving trauma patients aged 11 years and above, admitted to the surgical wards of Bugando Medical Centre in Mwanza, Tanzania over a six-month period from October 2008 to March 2009. All eligible patients were consecutively enrolled in the study. Data were collected using a pre-tested, coded questionnaire and analyzed using SPSS computer software. A total of 250 trauma patients were recruited and studied. The mean age of the study population was 36.37±15.35. Males accounted for the majority (N=202; 80.8%) of the study population. The prevalence of HIV among trauma patients was 11.6%. Among the HIV positive patients, 26 (89.7%) were males and majority aged 31-40 years. Seventy two percent of HIV positive patients had CD4+ count of ≥ 200 cells/μl. Overall length of hospital stays (LOS) ranged from 1 - 90 days with mean of 19.11 ± 15.84 days. Using multivariate logistic regression, injury severity score (ISS) (P=0.0026), revised trauma scores (RTS) (P= 0.002,), HIV seropositivity (P= 0.0012) and CD4+ count (P= 0.001) were significantly found to be associated with increased LOS. Mortality rate was 10.8% and was significantly associated with; the body region injured (P < 0.05), ISS (P = 0.026), RTS (P = 0.001), PTS (P= 0.01), HIV positivity (P= 0.0001) and CD4+ count (P= 0.035). HIV is prevalent among trauma patients in our setting. A substantial risk of exposure to HIV exists in health workers who care for these patients. Thus, all trauma health care workers in this region need to practice universal barrier precautions in order to reduce the risk of exposure to HIV infection. HIV positive patients with CD4+ count ≥200cells/μl have similar prognosis as HIV negative patients and therefore should be treated the same way

Motion of falling object

A simple setup was assembled to study the motion of an object while it falls. The setup was used to determine the instantaneous velocity, terminal velocity and acceleration due to gravity. Also, since the whole project was done within $20 it can easily be popularized.Comment: 11 pages, 4 figur