Transient and long-term antioxidant gene responses in Medicago truncatula following application of exogenous nitric oxide

Nitric oxide (NO) is a bioactive molecule involved in many biological events that has been reported to act as both a prooxidant and an antioxidant in plants. Several reports exist which investigate the protective action of low (f.lM) concentrations of sodium nitroprusside (SNP), a NO donor. It is now commonly accepted that NO acts as a signal molecule in plants possibly playing a role to induce/stabilize the expression of many antioxidant enzymes. This study attempts to provide novel insight into the effect of application of exogenous NO on transient and long-term antioxidant gene expression levels in the model plant Medicago truncatula following inhibition studies and a quantitative real-time peR approach. Our data suggest that exogenous NO leads to a transient (3hour) induction of several antioxidant genes examined including A ox, Apx and Cat, while expression levels appear to decline after 24 hours. NO- and ROS-dependent signalling pathways were detected to operate and differentially affect induction of the different antioxidant genes. Our data suggest that Cat expression is not affected directly by NO or ROS-signalling cascades. Aox induction by NO is affected by NO- and ROS-dependent signalling pathways while Apx induction by NO has NO-dependent but not ROS-dependent signalling components

Energies and structures of Cu/Nb and Cu/W interfaces from density functional theory and semi-empirical calculations

Cu/Me multilayer systems, with Me referring to a body-centered cubic () metal, such as Nb and W, are widely used for nuclear, electrical, and electronic applications. Despite making up only a small percentage of the volume, interfaces in such systems play a major role in determining their electrical, mechanical, thermal and diffusion properties. Face-centered cubic () Cu often forms Kurdjumov-Sachs (KS) and Nishiyama-Wassermann (NW) type interfaces with metals or variations thereof. For the Cu/Nb system, these interface relationships have been extensively studied with semi-empirical methods. Surprisingly, the energetics and interface properties of Cu/W have not yet been studied in detail, in spite of extensive applications. In this study, we employ both periodic Embedded Atom Method (EAM) and Density Functional Theory (DFT) simulations to explore the geometric and energetic properties of the KS and NW interfaces of Cu/Nb and Cu/W. To assess the reliability of our approach, the dependence of the results on the size of periodic cells is examined for coherent and incoherent interfaces. We provide the interface energies and the work of separation for the Cu/W and Cu/Nb interfaces at DFT accuracy. The results of calculations with two EAM potentials are in qualitative agreement with those obtained using DFT and allow investigating the convergence of interfacial properties. These key energetic quantities can be used for future thermodynamic and mechanical modeling of Cu/Me interfaces

On manifolds admitting the consistent Lagrangian formulation for higher spin fields

We study a possibility of Lagrangian formulation for free higher spin bosonic totally symmetric tensor field on the background manifold characterizing by the arbitrary metric, vector and third rank tensor fields in framework of BRST approach. Assuming existence of massless and flat limits in the Lagrangian and using the most general form of the operators of constraints we show that the algebra generated by these operators will be closed only for constant curvature space with no nontrivial coupling to the third rank tensor and the strength of the vector fields. This result finally proves that the consistent Lagrangian formulation at the conditions under consideration is possible only in constant curvature Riemann space.Comment: 11 pages; v2: minor typos corrected, a reference adde

On gravitational couplings in D-brane action

We compute the two closed string graviton - two open string scalar scattering amplitude on the disc to show that there is no second-derivative curvature - scalar coupling term R X^2 in the low-energy effective action of a D-brane in curved space in type II superstring theory.Comment: 15 pages, 1 figure, LaTex JHEP style; v2: reference added, typos corrected; v3: section 2 rewritten due to an error in gauge fixing, appendix added, conclusions unchange

BRST approach to Lagrangian formulation of bosonic totally antisymmeric tensor fields in curved space

We apply the BRST approach, previously developed for higher spin field theories, to gauge invariant Lagrangian construction for antisymmetric massive and massless bosonic fields in arbitrary d-dimensional curved space. The obtained theories are reducible gauge models both in massless and massive cases and the order of reducibility grows with the value of the rank of the antisymmetric field. In both the cases the Lagrangians contain the sets of auxiliary fields and possess more rich gauge symmetry in comparison with standard Lagrangian formulation for the antisymmetric fields. This serves additional demonstration of universality of the BRST approach for Lagrangian constructions in various field models.Comment: 12 page

D-branes and SQCD in Non-Critical Superstring Theory

Using exact boundary conformal field theory methods we analyze the D-brane physics of a specific four-dimensional non-critical superstring theory which involves the N=2 SL(2)/U(1) Kazama-Suzuki model at level 1. Via the holographic duality of hep-th/9907178 our results are relevant for D-brane dynamics in the background of NS5-branes and D-brane dynamics near a conifold singularity. We pay special attention to a configuration of D3- and D5-branes that realizes N=1 supersymmetric QCD and discuss the massless spectrum and classical moduli of this setup in detail. We also comment briefly on the implications of this construction for the recently proposed generalization of the AdS/CFT correspondence by Klebanov and Maldacena within the setting of non-critical superstrings.Comment: harvmac, 47 pages, 6 figures; v4 same as v3 due to submission erro

Astrophysical science metrics for next-generation gravitational-wave detectors

The second generation of gravitational-wave detectors are being built and tuned all over the world. The detection of signals from binary black holes is beginning to fulfill the promise of gravitational-wave astronomy. In this work, we examine several possible configurations for third-generation laser interferometers in existing km-scale facilities. We propose a set of astrophysically motivated metrics to evaluate detector performance. We measure the impact of detector design choices against these metrics, providing a quantitative cost-benefit analyses of the resulting scientific payoffs

D-branes in Unoriented Non-critical Strings and Duality in SO(N) and Sp(N) Gauge Theories

We exhibit exact conformal field theory descriptions of SO(N) and Sp(N) pairs of Seiberg-dual gauge theories within string theory. The N=1 gauge theories with flavour are realized as low energy limits of the worldvolume theories on D-branes in unoriented non-critical superstring backgrounds. These unoriented backgrounds are obtained by constructing exact crosscap states in the SL(2,R)/U(1) coset conformal field theory using the modular bootstrap method. Seiberg duality is understood by studying the behaviour of the boundary and crosscap states under monodromy in the closed string parameter space.Comment: 23 pages, 2 figure