Effective Action of Matter Fields in Four-Dimensional String Orientifolds

We study various aspects of the Kahler metric for matter fields in N=1,2 orientifold compactifications of type IIB string theory. The result has an infrared-divergent part which reproduces the field- theoretical anomalous dimensions, and a moduli-dependent part which comes from N=2 sectors of the orientifold. For the N=2 orientifolds, we also compute the disk amplitude for two matter fields on the boundary and a twisted closed string modulus in the bulk. Our results are in agreement with supersymmetry: the singlet under the SU(2)_R R-symmetry has vanishing coupling, while the coupling of the SU(2)_R triplet does not vanish.Comment: 24 pages, JHEP LaTex, no figures, v2: references added, typos correcte

Gene expression analysis of bovine embryonic disc, trophoblast and parietal hypoblast at the start of gastrulation

In cattle early gastrulation-stage embryos (Stage 5), four tissues can be discerned: (i) the top layer of the embryonic disc consisting of embryonic ectoderm (EmE); (ii) the bottom layer of the disc consisting of mesoderm, endoderm and visceral hypoblast (MEH); (iii) the trophoblast (TB); and (iv) the parietal hypoblast. We performed microsurgery followed by RNA-seq to analyse the transcriptome of these four tissues as well as a developmentally earlier pre-gastrulation embryonic disc. The cattle EmE transcriptome was similar at Stages 4 and 5, characterised by the OCT4/SOX2/NANOG pluripotency network. Expression of genes associated with primordial germ cells suggest their presence in the EmE tissue at these stages. Anterior visceral hypoblast genes were transcribed in the Stage 4 disc, but no longer by Stage 5. The Stage 5 MEH layer was equally similar to mouse embryonic and extraembryonic visceral endoderm. Our data suggest that the first mesoderm to invaginate in cattle embryos is fated to become extraembryonic. TGFβ, FGF, VEGF, PDGFA, IGF2, IHH and WNT signals and receptors were expressed, however the representative members of the FGF families differed from that seen in equivalent tissues of mouse embryos. The TB transcriptome was unique and differed significantly from that of mice. FGF signalling in the TB may be autocrine with both FGFR2 and FGF2 expressed. Our data revealed a range of potential inter-tissue interactions, highlighted significant differences in early development between mice and cattle and yielded insight into the developmental events occurring at the start of gastrulation

Heat content with singular initial temperature and singular specific heat

Let (M,g) be a compact Riemannian manifold without boundary. Let D be a compact subdomain of M with smooth boundary. We examine the heat content asymptotics for the heat flow from D into M where both the initial temperature and the specific heat are permitted to have controlled singularities on the boundary of D. The operator driving the heat process is assumed to be an operator of Laplace typ

Expected volume of intersection of Wiener sausages and heat kernel norms on compact Riemannian manifolds with boundary

Estimates are obtained for the expected volume of intersection of independent Wiener sausages in Euclidean space in the small time limit. The asymptotic behaviour of the weighted diagonal heat kernel norm on compact Riemannian manifolds with smooth boundary is obtained in the small time limi

The mechanism of pyridine hydrogenolysis on molybdenum-containing catalysts : II. Hydrogenation of pyridine to piperidine

The kinetics of pyridine hydrogenation was studied at high hydrogen pressures on a Mo-Al oxide and a Co-Mo-Al oxide catalyst. The rate equation was found to be r = kPpyrPH2n/Ppyro, in which n is 1.5 at 300 and 375 °C and 1.0 at 250 °C. This rate equation can be derived assuming strong adsorption of pyridine and its products with identical adsorption constants.\ud The (hydro)cracking of piperidine appears to have a low order in hydrogen, probably lower than 0.5.\ud The adsorption behavior of nitrogen bases and hydrogen on alumina and the molybdenum-containing catalysts was investigated by the gas chromatographic method. The adsorption of the nitrogen bases appeared to be very strong on both catalysts, and varied in the order piperidine > pyridine > ammonia.\ud Hydrogen also showed a strong adsorption. Hydrogen and nitrogen bases appeared to adsorb on different sites

Firm Culture and Leadership as Firm Performance Predictors: a Resource-Based Perspective

In this study, we tested part of the resource-based view of the firm by examining two 'soft' resources, firm culture and top leadership, as predictors of 'hard' or bottom-line firm performance.Transformational top leadership was found to predict firm performance directly while the link between firm culture and firm performance was indirect: via transformational top leadership.Firm culture was operationalized as the employees' views about the degree of optimization of four organizational practices (job autonomy, external orientational, interdepartmental orientation, and human resource orientation).We conclude that, rather than strong cultures, firms need best organizational practices and transformational leadership.Organizational culture;Leadership firm performance;Resource-based theory of the firm