U-duality and Network Configurations of Branes

We explicitly write down the invariant supersymmetry conditions for branes with generic values of moduli and U-duality charges in various space-time dimensions $D \leq 10$. We then use these results to obtain new BPS states, corresponding to network type structure of such branes.Comment: 26 pages, Latex, Title and Text modified (minor modifications), to appear in Int. Jour. Mod. Phys.

« S’appuyer sur la force et l’énergie des populations affectées »

La meilleure façon de lutter contre une catastrophe est de s’appuyer sur la force et l’énergie des populations affectées. Des aides financières extérieures pour la reconstruction des bâtiments sont toujours souhaitables, mais elles ne sont jamais suffisantes à elles seules pour permettre la reconstruction de leurs vies. Dans le cadre de nos missions de réduction de l’impact des catastrophes après le cyclone Orissa de 1999, le tremblement de terre de Bhuj en 2001, le Tsunami de 2004 ou encore ..

String Network and U-Duality

We discuss the generalization of recently discovered BPS configurations, corresponding to the planar string networks, to non-planar ones by considering the U-duality symmetry of type II string theory in various dimensions. As an explicit example, we analyze the string solutions in 8-dimensional space-time, carrying SL(3) charges, and show that by aligning the strings along various directions appropriately, one can obtain a string network which preserves 1/8 supersymmetry.Comment: 8 pages, latex, references added, minor modification

Meta-analysis and forest plots for sustainability of heavy load carrier equipment used in the industrial mining environment

It is a common recommendation not to attempt a reliability analysis with a small sample size. However, this is feasible after considering certain statistical methods. One such method is meta-analysis, which can be considered to assess the effectiveness of a small sample size by combining data from different studies. The method explores the presence of heterogeneity and the robustness of the fresh large sample size using sensitivity analysis. The present study describes the approach in the reliability estimation of diesel engines and the components of industrial heavy load carrier equipment used in mines for transporting ore. A meta-analysis is carried out on field-based small-sample data for the reliability of different subsystems of the engine. The level of heterogeneity is calculated for each subsystem, which is further verified by constructing a forest plot. The level of heterogeneity was 0 for four subsystems and 2.23% for the air supply subsystem, which is very low. The result of the forest plot shows that all the plotted points mostly lie either on the center line (line of no effect) or very close to it, for all five subsystems. Hence, it was found that the grouping of an extremely small number of failure data is possible. By using this grouped TBF data, reliability analysis could be very easily carried out.The authors are grateful to FCT—Fundação para a Ciência e Tecnologia—who financially supported this work through the RD Units Project Scope: UIDP/04077/2020 and UIDB/04077/202

Curved Membrane Solutions in D=11 Supergravity

We present a class of static membrane solutions, with non-flat worldvolume geometry, in the eleven dimensional supergravity with source terms. This class of solutions contains supersymmetric as well as a large class of non-supersymmetric configurations. We comment about near horizon limit and stability of these solutions and point out an interesting relation with certain two dimensional dilaton gravity system.Comment: 16 pages, latex, to appear in IJMP A; acknowledgement and references adde

Synthesis of Silver Nanostructures and their Application in Highly Sensitive SERS Sensors

A comparison of Surface Enhanced Raman Scattering (SERS) activity of chemically synthesised silver nanostructures with different shapes is reported. The silver nanostructures of cubical, prism and wire like morphology were synthesised using chemical synthesis route and utilised as SERS substrates. The sensors were fabricated by spin coating these materials over a Silicon or glass substrate. The fabricated sensors were used to analyse response with two different analytes, 4-Mercaptobenzoic acid and Rhodamine 6G under different concentrations. The signal enhancement was compared with a silver coated thin film over glass substrate and it was observed that the enhancement of the order of 103 is achieved. The nanowire performed better than the other forms of silver and gave a higher signal enhancement for all the analytes as compared to other nanostructures. The fabricated sensors may be useful for various applications including explosive and biowarfare agent detection

Child malnutrition and recurrent flooding in rural eastern India: a community-based survey

Objectives This study aims to improve the understanding of the relationship between exposure to floods and malnutrition in children aged 6-59 months in rural India. Research has focused exclusively on Bangladeshi children, and few controlled epidemiological studies are available. Method A community-based cross-sectional study of child nutritional status was carried out in 14 flooded and 18 non-flooded villages of Jagatsinghpur district (Orissa) within one month of the September 2008 floods, and similarly affected by flooding in August 2006. Face-to-face interviews were conducted in 757 households in the flooded villages and 816 in the non-flooded communities. Data used in this study were from those households with children aged 6-59 months. In total, 191 and 161 children were measured, respectively. The association between various malnutrition indicators and the exposure to floods was assessed by univariate and multivariate logistic regression. Results Adjusted analyses revealed that children in flooded households were more likely stunted compared with those in non-flooded ones (adjusted prevalence ratio 1.60; 95% CI 1.05 to 2.44). The prevalence of underweight was also higher in children living in the flooded communities (adjusted prevalence ratio 1.86; 95% CI 1.04 to 3.30). Further analyses found that the 26-36-month flooded cohort, thus those children younger than 1 year during the precedent flood in August 2006, attained the largest difference in levels of stunting compared with the unexposed group of the same age. Conclusion Exposure to floods is associated with long-term malnutrition in these rural communities of Orissa, India. Children exposed to floods during their first year of life presented higher levels of chronic malnutrition. Long-term malnutrition prevention programmes after floods should be implemented in flood-prone areas

String Multiplets from an Invariant 2-Brane

We study a three-dimensional gauge theory obtained from the dimensional reduction of a D4-brane worldvolume theory in the background of space-time moduli. An SL(3) symmetry in this theory, which acts on fields as well as coupling constants, is identified. By comparing the energies with the string tensions, we show that certain 1/2 supersymmetric classical solutions of this theory can be identified as SL(3,Z) multiplets of type II strings in eight dimensions. Results are then generalized to the non-linear Born-Infeld action. We also discuss the possibility of 1/8 BPS states in this theory and their representations in terms of string networks.Comment: 17 pages, Latex, minor correction