Spin-2 spectrum of defect theories

We study spin-2 excitations in the background of the recently-discovered type-IIB solutions of D'Hoker et al. These are holographically-dual to defect conformal field theories, and they are also of interest in the context of the Karch-Randall proposal for a string-theory embedding of localized gravity. We first generalize an argument by Csaki et al to show that for any solution with four-dimensional anti-de Sitter, Poincare or de Sitter invariance the spin-2 excitations obey the massless scalar wave equation in ten dimensions. For the interface solutions at hand this reduces to a Laplace-Beltrami equation on a Riemann surface with disk topology, and in the simplest case of the supersymmetric Janus solution it further reduces to an ordinary differential equation known as Heun's equation. We solve this equation numerically, and exhibit the spectrum as a function of the dilaton-jump parameter $\Delta\phi$. In the limit of large $\Delta\phi$ a nearly-flat linear-dilaton dimension grows large, and the Janus geometry becomes effectively five-dimensional. We also discuss the difficulties of localizing four-dimensional gravity in the more general backgrounds with NS5-brane or D5-brane charge, which will be analyzed in detail in a companion paper.Comment: 41 pages, 6 figure

Structural Biology of Human H3K9 Methyltransferases

SET domain methyltransferases deposit methyl marks on specific histone tail lysine residues and play a major role in epigenetic regulation of gene transcription. We solved the structures of the catalytic domains of GLP, G9a, Suv39H2 and PRDM2, four of the eight known human H3K9 methyltransferases in their apo conformation or in complex with the methyl donating cofactor, and peptide substrates. We analyzed the structural determinants for methylation state specificity, and designed a G9a mutant able to tri-methylate H3K9. We show that the I-SET domain acts as a rigid docking platform, while induced-fit of the Post-SET domain is necessary to achieve a catalytically competent conformation. We also propose a model where long-range electrostatics bring enzyme and histone substrate together, while the presence of an arginine upstream of the target lysine is critical for binding and specificity. Enhanced version: This article can also be viewed as an enhanced version in which the text of the article is integrated with interactive 3D representations and animated transitions. Please note that a web plugin is required to access this enhanced functionality. Instructions for the installation and use of the web plugin are available i

Awareness and knowledge of sexually transmitted diseases (STDs) among school-going adolescents in Europe: a systematic review of published literature

Samkange-Zeeb FN, Spallek L, Zeeb H. Awareness and knowledge of sexually transmitted diseases (STDs) among school-going adolescents in Europe: a systematic review of published literature. BMC public health. 2011;11(1): 727.BACKGROUND: Sexually transmitted diseases (STDs) are a major health problem affecting mostly young people, not only in developing, but also in developed countries.We conducted this systematic review to determine awareness and knowledge of school-going male and female adolescents in Europe of STDs and if possible, how they perceive their own risk of contracting an STD. Results of this review can help point out areas where STD risk communication for adolescents needs to be improved. METHODS: Using various combinations of the terms "STD", "HIV", "HPV", "Chlamydia", "Syphilis", "Gonorrhoea", "herpes", "hepatitis B", "knowledge", "awareness", and "adolescents", we searched for literature published in the PubMed database from 01.01.1990 up to 31.12.2010. Studies were selected if they reported on the awareness and/or knowledge of one or more STD among school-attending adolescents in a European country and were published in English or German. Reference lists of selected publications were screened for further publications of interest. Information from included studies was systematically extracted and evaluated. RESULTS: A total of 15 studies were included in the review. All were cross-sectional surveys conducted among school-attending adolescents aged 13 to 20 years. Generally, awareness and knowledge varied among the adolescents depending on gender.Six STDs were focussed on in the studies included in the review, with awareness and knowledge being assessed in depth mainly for HIV/AIDS and HPV, and to some extent for chlamydia. For syphilis, gonorrhoea and herpes only awareness was assessed. Awareness was generally high for HIV/AIDS (above 90%) and low for HPV (range 5.4%-66%). Despite knowing that use of condoms helps protect against contracting an STD, some adolescents still regard condoms primarily as an interim method of contraception before using the pill. CONCLUSION: In general, the studies reported low levels of awareness and knowledge of sexually transmitted diseases, with the exception of HIV/AIDS. Although, as shown by some of the findings on condom use, knowledge does not always translate into behaviour change, adolescents' sex education is important for STD prevention, and the school setting plays an important role. Beyond HIV/AIDS, attention should be paid to infections such as chlamydia, gonorrhoea and syphilis

Synthesis and investigation of antimicrobial and antioxidant activity of anthraquinonylhydrazones

The new anthraquinonylhydrazones were obtained by the interaction of 9,10-dioxoanthracene-1-diazonium sulfates with a number of alpha- and beta-carbonyl-containing compounds under modified conditions of the Japp-Klingemann reaction, and a probable mechanism of the formation has been proposed. It was found that hydrazones, unsaturated in the second position of the anthraquinone ring, containing acetyl or ethoxycarbonyl moieties in the ylidene part of the molecule, are capable of eliminating these fragments. It has been experimentally established that hydrazones, free rotation around the N=C bond of which is possible, exist as one isomer due to the presence of an intramolecular hydrogen bond in the molecule. The anthraquinonylhydrazone of dimedone with action against the bacteria strains of Staphylococcus aureus 209-P, Mycobacterium luteum B-917, and fungus Candida tenuis VKM Y-70 was found. The hydrazones of dimedone and barbituric acid with a higher trolox equivalent antioxidant coefficients of antioxidant action were found using CUPRAC assay. In addition, the hydrazones of dimedone and barbituric acid exhibited better activity against catalase enzyme. Correlations between the structure of the synthesized hydrazones and their antioxidant activity have been defined