Branes and Geometry in String and M-Theory

This thesis is based on two papers by the author and consists of two parts. We review the recent developments in the theory of multiple M2-branes and 3-algebras leading to multiple D2-brane theories. The inclusion of flux terms for the supersymmetric BLG and ABJM theories of closed M2-branes is discussed and then generalised to open M2-branes. Here the boundary condition is derived and different BPS configurations are examined where we find a mass deformed Basu-Harvey equation for the M2-M5 system. The Lorentzian 3-algebra is then employed for obtaining a theory of D2-branes in a flux background, we then obtain the new fuzzy funnel solution of the system of D2-D4 branes in a flux. Matrix theories and their compactifications as well as noncommutative geometry and noncommutative gauge theories are reviewed with a discussion of their generalisations to three dimensions to be used to describe the M-theory three form potential $C_3$. A new feature of string theory is then obtained called the quantum Nambu geometry (QNG). It is found by considering the action for D1-strings in a RR flux background and we demonstrate that there is a large flux double scaling limit where the action is dominated by a Chern-Simons-Myers coupling term. A classical solution to this is the quantised spacetime known as the quantum Nambu geometry. Various matrix models are obtained from this action, these are the large flux dominated terms of the full actions for the corresponding matrix models. The QNG gives rise to an expansion of D1-strings to D4-branes in the IIA theory, so we obtain an action for the large flux terms for this action which is verified by a dimensional reduction of the PST action describing M5-branes. We make a generalisation of the D4-brane action to describe M5-branes using a duality. We are describing the 3-form self-dual field strength of a non-abelian generalisation of the PST action.Comment: PhD Thesis, 143 page

Student Advising and Retention Application in Cloud Computing Environment

This paper proposes a new user-friendly application enhancing and expanding the current advising services of Gradesfirst currently being used for advising and retention by the Athletic department of UMES with a view to implement new performance activities like mentoring, tutoring, scheduling, and study hall hours into existing tools. This application includes various measurements that can be used to monitor and improve the performance of the students in the Athletic Department of UMES by monitoring students' weekly study hall hours, and tutoring schedules. It also supervises tutors' login and logout activities in order to monitor their effectiveness, supervises tutor-tutee interaction, and stores and analyzes the overall academic progress of each student. A dedicated server for providing services will be developed at the local site. The paper has been implemented in three steps. The first step involves the creation of an independent cloud computing environment that provides resources such as database creation, query-based statistical data, performance measures activities, and automated support of performance measures such as advising, mentoring, monitoring and tutoring. The second step involves the creation of an application known as Student Advising and Retention (SAR) application in a cloud computing environment. This application has been designed to be a comprehensive database management system which contains relevant data regarding student academic development that supports various strategic advising and monitoring of students. The third step involves the creation of a systematic advising chart and frameworks which help advisors. The paper shows ways of creating the most appropriate advising technique based on the student's academic needs. The proposed application runs in a Windows-based system. As stated above, the proposed application is expected to enhance and expand the current advising service of Gradesfirst tool. A brief demonstration of the proposed application will highlight the main features of the existing tool (Gradefirst)

Systematic Reviews of Genetic Association Studies

Gurdeep S. Sagoo and colleagues describe key components of the methodology for undertaking systematic reviews and meta-analyses of genetic association studies

Comparison of risk profile in pre-menopausal and post-menopausal women with acute coronary syndrome

Background: The physiological changes associated with menopause are responsible for increase in cardiovascular disease after menopause. BMI, physical inactivity, metabolic syndrome, hypertension and diabetes mellitus increase in post-menopausal women which are all powerful predictors of cardiovascular events. The risk factor profile between pre-menopausal and post-menopausal women presenting with acute coronary syndrome was thus studied.Methods: This study was a prospective cross-sectional hospital based study and was conducted in the Department of Medicine and Department of Cardiology, Dayanand Medical College and Hospital, Ludhiana wherein 50 pre-menopausal women and 50 post- menopausal women who presented with acute coronary syndrome were enrolled. The risk factor profile and angiography findings amongst the 2 groups were compared.Results: There was no difference in the incidence of Diabetes Mellitus and Hypertension among the pre & post-menopausal groups. The prevalence of family history of cardiovascular disease was higher in the pre-menopausal group. The post-menopausal women showed a significant decrease in physical activity due to sedentary lifestyle. Both the groups had high BMI and increased waist circumference. Lipid parameters did not show any significant difference between the two groups. However, pre-menopausal women had higher LDL-C and triglyceride levels and lower HDL-C levels. On analysis of the angiographic findings in diabetics and non-diabetics, of both the groups diabetes mellitus was much higher in subjects presenting with triple vessel disease suggesting extensive atherosclerosis.Conclusions: study showed physical inactivity as an important cardiovascular risk factor in post-menopausal women. Obesity is an important risk factor for coronary artery disease in both pre- and post-menopausal women

Key role of quinone in the mechanism of respiratory complex I

Complex I is the first and the largest enzyme of respiratory chains in bacteria and mitochondria. The mechanism which couples spatially separated transfer of electrons to proton translocation in complex I is not known. Here we report five crystal structures of T. thermophilus enzyme in complex with NADH or quinone-like compounds. We also determined cryo-EM structures of major and minor native states of the complex, differing in the position of the peripheral arm. Crystal structures show that binding of quinone-like compounds (but not of NADH) leads to a related global conformational change, accompanied by local re-arrangements propagating from the quinone site to the nearest proton channel. Normal mode and molecular dynamics analyses indicate that these are likely to represent the first steps in the proton translocation mechanism. Our results suggest that quinone binding and chemistry play a key role in the coupling mechanism of complex I

Closure methods of the appendix stump for complications during laparoscopic appendectomy

BACKGROUND: Laparoscopic appendectomy is amongst the most common general surgical procedures performed in the developed world. Arguably, the most critical part of this procedure is effective closure of the appendix stump to prevent catastrophic intra-abdominal complications from a faecal leak into the abdominal cavity. A variety of methods to close the appendix stump are used worldwide; these can be broadly divided into traditional ligatures (such as intracorporeal or extracorporeal ligatures or Roeder loops) and mechanical devices (such as stapling devices, clips, or electrothermal devices). However, the optimal method remains unclear. OBJECTIVES: To compare all surgical techniques now used for appendix stump closure during laparoscopic appendectomy. SEARCH METHODS: In June 2017, we searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 6) in the Cochrane Library, MEDLINE Ovid (1946 to 14 June 2017), Embase Ovid (1974 to 14 June 2017), Science Citation Index - Expanded (14 June 2017), China Biological Medicine Database (CBM), the World Health Organization International Trials Registry Platform search portal, ClinicalTrials.gov, Current Controlled Trials, the Chinese Clinical Trials Register, and the EU Clinical Trials Register (all in June 2017). We searched the reference lists of relevant publications as well as meeting abstracts and Conference Proceedings Citation Index to look for additional relevant clinical trials. SELECTION CRITERIA: We included all randomised controlled trials (RCTs) that compared mechanical appendix stump closure (stapler, clips, or electrothermal devices) versus ligation (Endoloop, Roeder loop, or intracorporeal knot techniques) for uncomplicated appendicitis. DATA COLLECTION AND ANALYSIS: Two review authors identified trials for inclusion, collected data, and assessed risk of bias independently. We performed the meta-analysis using Review Manager 5. We calculated the odds ratio (OR) for dichotomous outcomes and the mean difference (MD) for continuous outcomes, with 95% confidence intervals (CIs). MAIN RESULTS: We included eight randomised studies encompassing 850 participants. Five studies compared titanium clips versus ligature, two studies compared an endoscopic stapler device versus ligature, and one study compared an endoscopic stapler device, titanium clips, and ligature. In our analyses of primary outcomes, we found no differences in total complications (OR 0.97, 95% CI 0.27 to 3.50, 8 RCTs, very low-quality evidence), intraoperative complications (OR 0.93, 95% CI 0.34 to 2.55, 8 RCTs, very low-quality evidence), or postoperative complications (OR 0.80, 95% CI 0.21 to 3.13, 8 RCTs, very low-quality evidence) between ligature and all types of mechanical devices. However, our analyses of secondary outcomes revealed that use of mechanical devices saved approximately nine minutes of total operating time when compared with use of a ligature (mean difference (MD) -9.04 minutes, 95% CI -12.97 to -5.11 minutes, 8 RCTs, very low-quality evidence). However, this finding did not translate into a clinically or statistically significant reduction in inpatient hospital stay (MD 0.02 days, 95% CI -0.12 to 0.17 days, 8 RCTs, very low-quality evidence). Available information was insufficient for reliable comparison of total hospital costs and postoperative pain/quality of life between the two approaches. Overall, evidence across all analyses was of very low quality, with substantial potential for confounding factors. Given the limitations of all studies in terms of bias and the low quality of available evidence, a clear conclusion regarding superiority of any one particular type of mechanical device over another is not possible. AUTHORS' CONCLUSIONS: Evidence is insufficient at present to advocate omission of conventional ligature-based appendix stump closure in favour of any single type of mechanical device over another in uncomplicated appendicitis