Magnetic field induced Coulomb blockade in small disordered delta-doped heterostructures

At low densities, electrons confined to two dimensions in a delta-doped heterostructure can arrange themselves into self-consistent droplets due to disorder and screening effects. We use this observation to show that at low temperatures, there should be resistance oscillations in low density two dimensional electron gases as a function of the gate voltage, that are greatly enhanced in a magnetic field. These oscillations are intrinsic to small samples and give way to variable range hopping resistivity at low temperatures in larger samples. We place our analysis in the context of recent experiments where similar physical effects have been discussed from the point of view of a Wigner crystal or charge density wave picture.Comment: 6 pages RevTeX, 2 figures, published versio

Spectroscopic Diagnostic of the Footpoints of the Cool loops

Statistically, the cool loop's footpoints are diagnosed using Si~{\sc iv} resonance lines observations provided by Interface Region Imaging Spectrograph (IRIS). The intensity and Full Width at Half Maximum (FWHM) of the loop's footpoints in $\beta${--}$\gamma$ active regions (ARs) are higher than the corresponding parameters of footpoints in $\beta$ ARs. However, the Doppler velocity of footpoints in both ARs are almost similar to each other. The intensities of footpoints from $\beta${--}$\gamma$ AR is found to be around 9 times that of $\beta$ AR when both ARs are observed nearly at the same time. The same intensity difference reduces nearly to half (4 times) when considering all ARs observed over 9 years. Hence, the instrument degradation affects comparative intensity analysis. We find that Doppler velocity and FWHM are well-correlated while peak intensity is neither correlated with Doppler velocity nor FWHM. The loop's footpoints in $\beta$-$\gamma$ ARs have around four times more complex Si~{\sc iv} spectral profiles than that of $\beta$ ARs. The intensity ratios (Si~{\sc iv} 1393.78~{\AA}/1402.77~{\AA}) of the significant locations of footpoints differ, marginally, (i.e., either less than 1.9 or greater than 2.10) from the theoretical ratio of 2, i.e., 52\% (55\%) locations in $\beta$ ($\beta${--}$\gamma$) ARs significantly deviate from 2. Hence, we say that more than half of the footpoint locations are either affected by the opacity or resonance scattering. We conclude that the nature and attributes of the footpoints of the cool loops in $\beta$-$\gamma$ ARs are significantly different from those in $\beta$ ARs.Comment: 17 pages, 12 Figures (11 main + 1 appendix), Accepted for Publication in MNRA

Medium/high field magnetoconductance in chaotic quantum dots

The magnetoconductance G in chaotic quantum dots at medium/high magnetic fluxes Phi is calculated by means of a tight binding Hamiltonian on a square lattice. Chaotic dots are simulated by introducing diagonal disorder on surface sites of L x L clusters. It is shown that when the ratio W/L is sufficiently large, W being the leads width, G increases steadily showing a maximum at a flux Phi_max ~ W. Bulk disordered ballistic cavities (with an amount of impurities proportional to L) does not show this effect. On the other hand, for magnetic fluxes larger than that for which the cyclotron radius is of the order of L/2, the average magnetoconductance inceases almost linearly with the flux with a slope proportional to W^2, shows a maximum and then decreases stepwise. These results closely follow a theory proposed by Beenakker and van Houten to explain the magnetoconductance of two point contacts in series.Comment: RevTeX including six postscript figure

Development of Readout Interconnections for the Si-W Calorimeter of SiD

The SiD collaboration is developing a Si-W sampling electromagnetic calorimeter, with anticipated application for the International Linear Collider. Assembling the modules for such a detector will involve special bonding technologies for the interconnections, especially for attaching a silicon detector wafer to a flex cable readout bus. We review the interconnect technologies involved, including oxidation removal processes, pad surface preparation, solder ball selection and placement, and bond quality assurance. Our results show that solder ball bonding is a promising technique for the Si-W ECAL, and unresolved issues are being addressed.Comment: 8 pages + title, 6 figure

Knowledge and attitude towards emergency contraception among undergraduate medical students

Background: Studying the knowledge and attitude of medical students towards emergency contraception, as they are the future medical professionals and they will serve as the main channel for providing proper knowledge and making positive impression of it in general population. The objective of the study was to assess the knowledge and attitude of undergraduate medical students towards emergency contraception.Methods: Medical students were given pre-validated questionnaire and divided in two groups. Group A students did not learn about emergency contraception, whereas group B students learnt about it. Interview of both groups were conducted separately. For group A, 1 hour seminar was conducted and after 7 days, same questionnaire was provided again for data collection.Results: 154 students were included in group A whereas 162 students in group B. Average knowledge and attitude was significantly increased after seminar in group A [knowledge 41±16.88% vs. 59.32±14.46%; P<0.05; attitude 36.24±10.93 vs. 41.5±10.87; P<0.05]. Average knowledge of group B students was 64.73±12.15% whereas average attitude score was 42.9±9.79. Amongst all, 86.4%, 87% and 89.3% students were not able to describe about emergency contraception, different methods and advantages of intra-uterine device as emergency contraception, respectively. There are 82.1% students showed positive interest in learning more about emergency contraception and 70.1% agreed to recommend its use in future. Students having good knowledge showed more positive attitude towards emergency contraception [r= 0.41, P<0.05].Conclusions: Students have poor knowledge of special issues arises with emergency contraception. Proper attention should be given to these aspects during their teaching. Students have shown their positive interest to learn more about emergency contraception. Objective based seminar will be more helpful in improving knowledge and attitude

Prescribing pattern in patients of asthma visiting outpatient departments of a tertiary care hospital: a cross-sectional, observational study

Background: Objective of the study was to evaluate the prescribing pattern in patients of asthma visiting outpatient departments.Methods: Collected prescriptions were analyzed for demographic variables, proportions of various comorbid conditions, average number of drugs per prescription, average number of anti-asthmatic drugs per prescription, proportion of prescription with antibiotics, fixed dose combinations, and generic/brand names, proportion of formulations utilized, proportion of concomitant medications and possible drug interactions, average cost per prescription, average cost of antiasthmatic drugs per prescription, proportion of irrational prescription and adverse drug reactions.Results: Total 139 prescriptions were evaluated. Deriphyllin was the most commonly prescribed anti-asthmatic drug followed by beta agonist- steroid combination. Majority drugs were prescribed by inhalational route. Deriphyllin, and dexamethasone were prescribed by oral route and salbutamol was by both oral and inhalational route of administration. Antibiotics were prescribed to 24 patients. Possible drug interaction with deriphyllin was found in 15 prescriptions. Average cost per prescription was Rs. 193.4 (95%CI: 171.6-215.3).Conclusions: Prescribing pattern of asthma in our hospital shows more use of anti-asthmatic drugs. Standard treatment guideline should be followed. Role of methylxanthine in long term management of asthma should be justified

Analysis of spontaneously reported adverse drug reactions to pharmacovigilance cell of a tertiary care hospital

Background: The objective of the study was to study the clinical patterns, causality and severity of adverse drug reactions in a tertiary care hospital.Methods: Total 131 ADR forms were collected from January 2012 to December 2012 and evaluated. Patient’s characteristics, ADR and drug characteristics, causality, severity and preventability of collected ADR were analyzed.Results: Total 131 ADR forms were evaluated. Male patient experiencing ADR were more (73, 55.7%) than female (58, 44.2%). Adult patients (12-60 years) experienced 110 (84%) ADR followed by pediatric patients (60 years) 10 (7.63%). Antimicrobial were the most common group of drugs responsible for ADR followed by NSAIDs and antipsychotic group.Conclusions: Present study shows lack of awareness among health care professionals for reporting of an ADR. Training and collaboration of health care professionals are needed for improvement in ADR reporting. Appropriate feedback from ADR reporting will help in selection of drug and promotes safer use of drugs