Photo induced ionization dynamics of the nitrogen vacancy defect in diamond investigated by single shot charge state detection

The nitrogen-vacancy centre (NV) has drawn much attention for over a decade, yet detailed knowledge of the photophysics needs to be established. Under typical conditions, the NV can have two stable charge states, negative (NV-) or neutral (NV0), with photo induced interconversion of these two states. Here, we present detailed studies of the ionization dynamics of single NV centres in bulk diamond at room temperature during illumination in dependence of the excitation wavelength and power. We apply a recent method which allows us to directly measure the charge state of a single NV centre, and observe its temporal evolution. Results of this work are the steady state NV- population, which was found to be always < 75% for 450 to 610 nm excitation wavelength, the relative absorption cross-section of NV- for 540 to 610 nm, and the energy of the NV- ground state of 2.6 eV below the conduction band. These results will help to further understand the photo-physics of the NV centre.Comment: 9 pages, 7 figure

The Journey of Insulin: Leaving a Legacy as a Medical Student

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Fourth-generation SM imprints in B -> K^*l^+l^- decays with polarized K^*

The implication of the fourth-generation quarks in the B -> K^*l^+l^- (l=mu,tau) decays, when K^* meson is longitudinally or transversely polarized, is presented. In this context, the dependence of the branching ratio with polarized K^* and the helicity fractions (f_{L,T}) of K^* meson are studied. It is observed that the polarized branching ratios as well as helicity fractions are sensitive to the NP parameters, especially when the final state leptons are tauons. Hence the measurements of these observables at LHC can serve as a good tool to investigate the indirect searches of new physics beyond the Standard Model.Comment: 13 pages, 10 figures, V2: some of the graphs are modified according to the new data from recent experiments. arXiv admin note: substantial text overlap with arXiv:1107.569

Knowledge, attitudes and practices around health research: the perspective of physicians-in-training in Pakistan

<p>Abstract</p> <p>Background</p> <p>Health research training is an essential component of medical education and a vital exercise to help develop physician research skills. This study was carried out to assess the level of knowledge, attitudes and practices towards research amongst a group of Post Graduate Medical Trainees (PGMTs') at Aga Khan University (AKU), Pakistan.</p> <p>Methods</p> <p>A cross sectional health research survey was carried out on all PGMTs' at AKU Pakistan. AKU is a tertiary care health facility which offers residency in 28 specialties and fellowship in 16 programs. Knowledge, attitudes and practices related to health research were assessed using a pretested, structured and validated questionnaire. Health research related practices of the residents were examined using questions graded on Likert scale.</p> <p>Results</p> <p>Mean percentage score ± SD on the knowledge scale was 36.9% ± 20.2 and 47.19% ± 25.18 on the attitude scale. Of 104(55.6%) who had previously participated in research 28(26.9%) had been involved in basic science research only, 62(59.6%) in clinical research and 14(13.5%) had participated in both clinical and basic science research projects. 88(47.1%) planned to pursue a future research career. Those who planned to pursue a future research career had more positive health research attitudes p < 0.001. Limited time (45%), poor research infrastructure (20%) and inadequate research funding opportunities (20%) were the major hurdles faced by PGMTs' to pursue research.</p> <p>Conclusion</p> <p>PGMTs' demonstrate inadequate knowledge, while they have moderate attitudes towards health research. Residency training and research facilities at the institution need to undergo major transformation in order to encourage meaningful research by resident trainees.</p

Salt stress induces genotype-specific DNA hypomethylation in ZmEXPB2 and ZmXET1 genes in maize

Maize, a moderately salt sensitive crop, first experiences osmotic stress that cause reduction in plant growth under salt stress. Fluctuation in cell wall elongation is one of the reasons of this reduction. Along with others, two important proteins expansins and xyloglucan endotransglucosylase are involved in regulation of cell wall elasticity, but the role of epigenetic mechanisms in regulating the cell wall related genes is still elusive. The present study was conducted with the aim of understanding the role of DNA methylation in regulating ZmEXPB2 and ZmXET1 genes. One salt sensitive and one salt tolerant maize cultivar was grown under hydroponic conditions at different levels of salt stress: T1 = 1 mM (control), T2 = 100 mM and T3 = 200 mM in three replicates. DNA and RNA were extracted from roots. After bisulfite treatment, Methyl Sensitive PCR was used for the DNA methylation analysis. It was revealed that fragment in promoter of ZmEXPB2 gene showed high level of DNA methylation under T1 in both varieties. Comparison of different stress treatments revealed decrease in DNA methylation with the increase in salt stress, significantly lower methylation appearing in T3. Similarly, the fragment in promoter of ZmXET1 gene also showed high levels of DNA methylation in T1. When different treatments were analysed, this gene significantly hypomethylated at T2 which continued to decrease in T3 in sensitive variety but remain stable in tolerant variety. Although, further in-depth analysis is required, our results demonstrate region-specific and genotype-specific methylation shift in the promoter of the ZmEXPB2 and ZmXET1 genes when subjected to the salt stress confirming the epigenetic regulation of these genes under stress conditions

Attitudes and practices of postgraduate medical trainees towards research--a snapshot from Faisalabad

Objective: To assess the attitudes and practices of postgraduate medical trainees towards research.Methods: It was a self-administered questionnaire based cross-sectional survey conducted on 55 conveniently selected trainees in Allied Hospital, Faisalabad.Results: Only 11 trainees read journals monthly, seven had written an article for a journal, 51 regarded reading literature important, 39 intended to engage in future research and 37 said they received inappropriate research training. The major reasons cited for poor research activity in Pakistan were poor research training and awareness.CONCLUSION: Though the attitudes towards research were positive, they were deficient practically in terms of reading and writing literature. There is an immediate need to improve research training in our educational institutes to facilitate the development of the local literature both in terms of research utilization and productio