Deformations of Cosmological Solutions of D=11 Supergravity

We study Lunin-Maldacena deformations of cosmological backgrounds of D=11 supergravity which gives an easy way to generate solutions with nonzero 4-form flux starting from solutions of pure Einstein equations which possess at least three U(1) isometries. We illustrate this on the vacuum S-brane solution from which the usual SM2-brane solution is obtained. Applying the method again, one either gets the recently found S-brane system where contribution of the Chern-Simons term to field equations is non-zero or the SM2-SM2(0) intersection, depending on which U(1) directions are used during the process. Repeated usage of the procedure gives rise to configurations with several overlapping S-branes some of which are new. We also employ this method to construct two more new solutions and make comments about accelerating cosmologies that follow from such deformed solutions after compactification to (1+3)-dimensions.Comment: v2:some comments and references adde

The TGFβ type I receptor TGFβRI functions as an inhibitor of BMP signaling in cartilage.

The type I TGFβ receptor TGFβRI (encoded by Tgfbr1) was ablated in cartilage. The resulting Tgfbr1 Col2 mice exhibited lethal chondrodysplasia. Similar defects were not seen in mice lacking the type II TGFβ receptor or SMADs 2 and 3, the intracellular mediators of canonical TGFβ signaling. However, we detected elevated BMP activity in Tgfbr1 Col2 mice. As previous studies showed that TGFβRI can physically interact with ACVRL1, a type I BMP receptor, we generated cartilage-specific Acvrl1 (Acvrl1 Col2 ) and Acvrl1/Tgfbr1 (Acvrl1/Tgfbr1 Col2 ) knockouts. Loss of ACVRL1 alone had no effect, but Acvrl1/Tgfbr1 Col2 mice exhibited a striking reversal of the chondrodysplasia seen in Tgfbr1 Col2 mice. Loss of TGFβRI led to a redistribution of the type II receptor ACTRIIB into ACVRL1/ACTRIIB complexes, which have high affinity for BMP9. Although BMP9 is not produced in cartilage, we detected BMP9 in the growth plate, most likely derived from the circulation. These findings demonstrate that the major function of TGFβRI in cartilage is not to transduce TGFβ signaling, but rather to antagonize BMP signaling mediated by ACVRL1

Effect of some natural antioxidants on aflatoxin B1-induced hepatic toxicity

Aflatoxins are potent hepatotoxic and hepatocarcinogenic agents. This hepatotoxicity is thought to be mediated by their ability to generate reactive oxygen species and cause peroxidative damage. In the present investigation we assessed the ability of some natural antioxidants namely, vitamin E and Se, ß-carotene, silymarin and coenzyme Q10 on aflatoxin B1 (AFB1)-induced hepatotoxicity in a rat model. Alanine and aspartate aminotransferases and alkaline phosphatase (ALP) were found to be significantly increased in the serum of AFB1 administered (250 µg/kg body weight/day for 2 weeks) rats, suggesting hepatic damage. There was a marked increase in the lipid peroxide levels and a concomitant decrease in the hepatic reduced glutathione (GSH) and serum protein thiol (PrSHs) along with a nearly twofold increase in hepatic glutathione-S-transferase (GST) activity. The significant increase in GST may be attributed to its being a phase ?? enzyme that predominately participates in the detoxification of the ultimate electrophilic metabolite AFB1-8, 9 epoxide. On the other hand, no significant change was detected in the activities of glutathione peroxidase (GPx), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G-6-PDH), cytochrome creductase and levels of DNA and RNA in the hepatic tissue of AFB1 administered rats. Results also revealed that cotreatment with studied antioxidants offered substantial hepatoprotective effects in the AFB1 administered rats. Moreover, results revealed that vitamin E and selenium combination and ß-carotene are more efficient than coenzyme Q10 and silymarin in modulating the liver antioxidant enzymatic system

Non-Standard Intersections of S-Branes in D=11 Supergravity

We construct new intersecting S-brane solutions in 11-dimensional supergravity which do not have supersymmetric analogs. They are obtained by letting brane charges to be proportional to each other. Solutions fall into two categories with respect to whether there is a non-diagonal term to be cancelled in the field equations or not. In each case we show that they can be constructed by using a simple set of rules which is similar to the harmonic function rule of the usual static p-branes. Furthermore, we study an intersection where the Chern-Simons term makes a non-zero contribution to the field equations. We show that this configuration has a singularity like other S-branes.Comment: 13 pages, 2 figures;v2 Section 2.2 is improved with new examples, references added;v3 typos correcte

Beta, Dipole and Noncommutative Deformations of M-theory Backgrounds with One or More Parameters

We construct new M-theory solutions starting from those that contain 5 U(1) isometries. We do this by reducing along one of the 5-torus directions, then T-dualizing via the action of an O(4,4) matrix and lifting back to 11-dimensions. The particular T-duality transformation is a sequence of O(2,2) transformations embedded in O(4,4), where the action of each O(2,2) gives a Lunin-Maldacena deformation in 10-dimensions. We find general formulas for the metric and 4-form field of single and multiparameter deformed solutions, when the 4-form of the initial 11-dimensional background has at most one leg along the 5-torus. All the deformation terms in the new solutions are given in terms of subdeterminants of a 5x5 matrix, which represents the metric on the 5-torus. We apply these results to several M-theory backgrounds of the type AdS_r x X^{11-r}. By appropriate choices of the T-duality and reduction directions we obtain analogues of beta, dipole and noncommutative deformations. We also provide formulas for backgrounds with only 3 or 4 U(1) isometries and study a case, for which our assumption for the 4-form field is violated.Comment: v2:minor corrections, v3:small improvements, v4:conclusions expanded, to appear in Class. Quant. Gra

Experimental and theoretical investigation of ligand effects on the synthesis of ZnO nanoparticles

ZnO nanoparticles with highly controllable particle sizes(less than 10 nm) were synthesized using organic capping ligands in Zn(Ac)2 ethanolic solution. The molecular structure of the ligands was found to have significant influence on the particle size. The multi-functional molecule tris(hydroxymethyl)-aminomethane (THMA) favoured smaller particle distributions compared with ligands possessing long hydrocarbon chains that are more frequently employed. The adsorption of capping ligands on ZnnOn crystal nuclei (where n = 4 or 18 molecular clusters of(0001) ZnO surfaces) was modelled by ab initio methods at the density functional theory (DFT) level. For the molecules examined, chemisorption proceeded via the formation of Zn...O, Zn...N, or Zn...S chemical bonds between the ligands and active Zn2+ sites on ZnO surfaces. The DFT results indicated that THMA binds more strongly to the ZnO surface than other ligands, suggesting that this molecule is very effective at stabilizing ZnO nanoparticle surfaces. This study, therefore, provides new insight into the correlation between the molecular structure of capping ligands and the morphology of metal oxide nanostructures formed in their presence

Do Citations make Impact on Social Media? : An Altmetric Analysis of Top Cited Articles of University of Madras, South India

Altmetrics is an emergent research area whereby social media is applied as a source of metrics to assess scholarly impact. Over the most recent couple of years, the enthusiasm for altmetrics has developed, offering ascend to numerous inquiries in regards to their potential advantages and difficulties. As another developing field, Altmetrics has turned into a trailblazer, and got a decent arrangement of consideration by specialists associated with the assessment of logical research. This paper aims to analyse top 15 articles of University of Madras which have scored high citations. It aims to find out to what extend the top cited articles have secured altmetric scores. Do the citation score really create any impact on the social media? This is the research question formulated and comparing tool features, social media data sources, and social media events provided by Altmetric aggregators and thus they are analysed. Spearman Rank correlation metrics shows high correlation between the ranks of citations and Altmetric scores. The tweeter and Mendeley are the media through the scholarly communication highly disseminate. The analysis of readers shows that United States tops the list, followed by United Kingdom and Spain and are mainly educational ones with Ph.D, Post Graduate and Masters. The Practitioners are observed to be the voracious readers of the social media resulting in the present altmetric analysis

Research Output Analysis of Top Six Universities of Tamil Nadu, India : A Scientometric View

Scientometrics is an important field of information science as it represents a unique set of techniques and tools for the monitoring and analysis of information resources and for the management of knowledge in social and organizational contexts. This article analysed the various Scientometric components of the articles published by top six universities of Tamil Nadu from 2000-2017. The study identifies research trend, characteristics growth and collaboration pattern of published literature. The analysis of data reveals that the average growth rate increases at the rate of 9.76%. Further, the average citation per paper observed is 12.18%. High degree of international collaboration is notified and USA and South Korea are found to be the most preferred collaborative countries. The CAGR calculated for six universities are 9.76. The major research publications outputs are from the field of Chemistry, Crystallography and Pharmacy

Research Output Analysis of Top Six Universities of Tamil Nadu, India : A Scientometric View

Scientometrics is an important field of information science as it represents a unique set of techniques and tools for the monitoring and analysis of information resources and for the management of knowledge in social and organizational contexts. This article analysed the various Scientometric components of the articles published by top six universities of Tamil Nadu from 2000-2017. The study identifies research trend, characteristics growth and collaboration pattern of published literature. The analysis of data reveals that the average growth rate increases at the rate of 9.76%. Further, the average citation per paper observed is 12.18%. High degree of international collaboration is notified and USA and South Korea are found to be the most preferred collaborative countries. The CAGR calculated for six universities are 9.76. The major research publications outputs are from the field of Chemistry, Crystallography and Pharmacy