Vibrating Winding Branes, Wrapping Democracy and Stabilization of Extra Dimensions in Dilaton Gravity

We show that, in the context of dilaton gravity, a recently proposed democratic principle for intersection possibilities of branes winding around extra dimensions yield stabilization, even with the inclusion of momentum modes of the wrapped branes on top of the winding modes. The constraints for stabilization massaged by string theory inputs forces the number of observed dimensions to be three. We also discuss consequences of adding ordinary matter living in the observed dimensions.Comment: Added a section discussing the linear and non-linear stability of the equilibrium point of the scale factors of the extra dimensions. Corrected a typo in the original field equations and other typos. Added and changed references. Final version appeared in JHE

Target space duality and moduli stabilization in String Gas Cosmology

Motivated by string gas cosmology, we investigate the stability of moduli fields coming from compactifications of string gas on torus with background flux. It was previously claimed that moduli are stabilized only at a single fixed point in moduli space, a self-dual point of T-duality with vanishing flux. Here, we show that there exist other stable fixed points on moduli space with non-vanishing flux. We also discuss the more general target space dualities associated with these fixed points.Comment: 12 pages, 1 figur

The Cosmology of Massless String Modes

We consider the spacetime dynamics of a gas of closed strings in the context of General Relativity in a background of arbitrary spatial dimensions. Our motivation is primarily late time String Gas Cosmology, where such a spacetime picture has to emerge after the dilaton has stabilized. We find that after accounting for the thermodynamics of a gas of strings, only string modes which are massless at the self-dual radius are relevant, and that they lead to a dynamics which is qualitatively different from that induced by the modes usually considered in the literature. In the context of an ansatz with three large spatial dimensions and an arbitrary number of small extra dimensions, we obtain isotropic stabilization of these extra dimensions at the self-dual radius. This stabilization occurs for fixed dilaton, and is induced by the special string states we focus on. The three large dimensions undergo a regular Friedmann-Robertson-Walker expansion. We also show that this framework for late-time cosmology is consistent with observational bounds.Comment: 15 pages, no figures, references added (again

Wall influence on dynamics of a microbubble

The nonlinear dynamic behaviour of microscopic bubbles near a wall is investigated. The Keller-Miksis-Parlitz equation is adopted, but modified to account for the presence of the wall. This base model describes the time evolution of the bubble surface, which is assumed to remain spherical, and accounts for the effect of acoustic radiation losses owing to liquid compressibility in the momentum conservation. Two situations are considered: the base case of an isolated bubble in an unbounded medium; and a bubble near a solid wall. In the latter case, the wall influence is modeled by including a symmetrically oscillating image bubble. The bubble dynamics is traced using a numerical solution of the model equation. Subsequently, Floquet theory is used to accurately detect the bifurcation point where bubble oscillations stop following the driving ultrasound frequency and undergo period-changing bifurcations. Of particular interest is the detection of the subcritical period tripling and quadrupling transition. The parametric bifurcation maps are obtained as functions of non-dimensional parameters representing the bubble radius, the frequency and pressure amplitude of the driving ultrasound field and the distance from the wall. It is shown that the presence of the wall generally stabilises the bubble dynamics, so that much larger values of the pressure amplitude are needed to generate nonlinear responses.Comment: 25 pages, 14 figure

Two phase detonation studies

An experimental study of the passage of a shock wave over a burning fuel drop is described. This includes high speed framing photographs of the interaction taken at 500,000 frames per second. A theoretical prediction of the ignition of a fuel drop by a shock wave is presented and the results compared with earlier experimental work. Experimental attempts to generate a detonation in a liquid fuel drop (kerosene)-liquid oxidizer drop (hydrogen peroxide)-inert gas-environment are described. An appendix is included which gives the analytical prediction of power requirements for the drop generator to produce certain size drops at a certain mass rate. A bibliography is also included which lists all of the publications resulting from this research grant

Current trends in highly active anti-retroviral therapy in an anti-retroviral therapy centre attached to a remote government medical college of Maharashtra, India: a retrospective study

Background: Highly active anti-retroviral therapy (HAART) became the keystone of national AIDS program. There is lack of awareness and inadequate training about drug safety monitoring among health care professionals in India. Hence, the present study was carried out to study current trends in HAART and pattern of associated adverse drug reactions.Methods: A retrospective observational study was conducted at an anti-retroviral therapy (ART) Centre. A total of 151 HIV/AIDS Patients (old and new cases) receiving HAART during July 2015 to December 2015 were randomly included in the study. Causality and severity assessment of adverse drug reactions (ADRs) was done by using Naranjo’s ADR causality scale and modified Hartwig and Siegel scale respectively. The data was computed using MS Excel and descriptive results were expressed as counts and percentages. The study was approved by institutional ethics committee.Results: The prevalence of HIV/AIDS infection was higher in adult males (51.66%). Zidovudine+lamivudine+nevirapine (ZLN) was the most commonly prescribed HAART combination. Out of 132 ADRs reported, 76.52% of the ADRs were related to haematological system and ZLN was the commonest combination causing ADRs. 90.91% ADRs belong to possible category on causality assessment and 68.94% of the ADRs were of moderate severity. Tuberculosis (28.47%) was the commonest diagnosed opportunistic infection among the HIV/AIDS patients.Conclusions: The prescribing pattern of HAART regimens was in accordance with national guidelines for antiretroviral therapy. We recommend a pharmacovigilance system for sustainable management of ADRs in HIV/AIDS patients as we found under reporting of ADRs

Study of current prescribing pattern of antimicrobial drugs in indoor cases of enteric fever in a tertiary care hospital

Background: Rational antibiotic prescription is very important to prevent antimicrobial resistance. Hence the present study was conducted to evaluate the prescribing pattern of antimicrobial drugs in indoor enteric fever patients of medicine and paediatric department of a tertiary care hospital.Methods: A retrospective study of 2 months duration was undertaken during July and August of 2015. A total number of 97 enteric fever patients’ case sheets were utilized for our study from medicine and paediatric in-patients department of a tertiary care hospital. The data was analysed and results were expressed as percentage.Results: Out of 97 enteric fever patients, 54.64% were females. 13.4% of paediatric population were suffered because of enteric fever. The incidence of enteric fever was 74.23% in 13-40 years. Most commonly prescribed antimicrobials were 3rd generation cephalosporins and fluoroquinolones. 43.30% patients received more than one antibiotic. Antimalarials chloroquine, artemisinin derivatives and metronidazole were other drugs prescribed to enteric fever patients concurrently for associated clinical conditions.Conclusions: Interventional programme should focus on the use of rational antibiotic prescription aimed at minimizing unnecessary cost, adverse drug reactions and emergence of bacterial resistance

T and S dualities and The cosmological evolution of the dilaton and the scale factors

Cosmologically stabilizing radion along with the dilaton is one of the major concerns of low energy string theory. One can hope that T and S dualities can provide a plausible answer. In this work we study the impact of S and T duality invariances on dilaton gravity. We have shown various instances where physically interesting models arise as a result of imposing the mentioned invariances. In particular S duality has a very privileged effect in that the dilaton equations partially decouple from the evolution of the scale factors. This makes it easy to understand the general rules for the stabilization of the dilaton. We also show that certain T duality invariant actions become S duality invariance compatible. That is they mimic S duality when extra dimensions stabilize.Comment: Corrected a misleading interpretation of the S duality transformation and a wrong comment on d=10. I thank A.Kaya for pointing this out to me in time. So the new version is dealing with d=10 only. Added references and corrected some typos. Minor re-editing. Omitted a section for elaboration in a further study. Corrected further typo

Prescription pattern in indoor patients of cardiovascular diseases: a descriptive study in a tertiary care hospital attached to a government medical college

Background: In India, one of the leading causes of death is cardiovascular diseases (CVDs). The study of prescription pattern ensures rational pharmacotherapy and assures quality medical care to the patients. Hence the present study was conducted to observe the prescription pattern of drugs among the indoor patients of cardiovascular diseases in a tertiary care hospital attached to a Government Medical college.Methods: A retrospective observational study of 9 month duration was undertaken from January- September 2015. A total number of 113 indoor cardiovascular disease patients’ case sheets were utilized for our study from medicine and ICCU department of a tertiary care hospital. The data was analysed and the results were expressed as counts and percentage.Results: Of 113 patients, most of the patients were of the age group of 56-65 years (40.71%). The prevalence of CVDs was higher in females (56.64%) than males (43.36%). Hypertension (58.41%) and Ischemic heart disease (41.59%) were found to be predominant CVDs. Nifedipine (53.10%), Atenolol (31.86%), Isosorbide dinitrate (40.71%), Atorvastatin (53.10%) were the most commonly prescribed cardiovascular drugs. Aspirin and Clopidogrel combination was prescribed in 46.90% of CVD patients. The average number of drugs per prescription was 6.53.Conclusions: The present study shows that most of drugs were prescribed rationally according to the current treatment guidelines except the under use of ACEIs and ARBs in hypertensive diabetes mellitus patients. Standard treatment guidelines should be circulated among practicing physicians to encourage rational prescription