Pomerons and BCFW recursion relations for strings on D-branes

We derive pomeron vertex operators for bosonic strings and superstrings in the presence of D-branes. We demonstrate how they can be used in order to compute the Regge behavior of string amplitudes on D-branes and the amplitude of ultrarelativistic D-brane scattering. After a lightning review of the BCFW method, we proceed in a classification of the various BCFW shifts possible in a field/string theory in the presence of defects/D-branes. The BCFW shifts present several novel features, such as the possibility of performing single particle momentum shifts, due to the breaking of momentum conservation in the directions normal to the defect. Using the pomeron vertices we show that superstring amplitudes on the disc involving both open and closed strings should obey BCFW recursion relations. As a particular example, we analyze explicitly the case of 1 -> 1 scattering of level one closed string states off a D-brane. Finally, we investigate whether the eikonal Regge regime conjecture holds in the presence of D-branes.Comment: 49 pages; v2 corrected references and minor typos; v3 minor typos corrected, version to appear in NP

On the geography of international banking: the role of third-country effects

International banking is a complex phenomenon. Among its determinants, distance has been found to be critical. But does distance only have a simple negative direct effect? Or is the role of geography more intricate? Applying spatial analysis techniques on BIS data of bank foreign claims in 178 countries in 2006, evidence of positive spatial autocorrelation under alternative spatial weights schemes is brought to light. The geographical aspects of international banking are further explored by a spatial autoregressive gravity model. The results obtained support that the operation of a spatial lag leads to important indirect or third-country effects. Evidence of such financial spillovers is further corroborated by results of a spatial autoregressive Tobit model. Geography is more important than the effect of distance on its own would suggest. Third-country effects operate in a manner that subsequently connects countries through links beyond those immediately involved in borrowing (destination) and lending (origin) relationships. Confirming earlier results, the economic size of sending and recipient countries, cultural similarity and in-phase business cycles enhance international banking, while distance and exchange rate volatility hinder it. Also, while lower political risk has a positive role, so do higher financial and economic risks, reflecting-to some extent-some of the reasons behind the current financial crisis.international banking ;financial spillovers; gravity model; spatial econometrics

Interacting Higher Spins and the High Energy Limit of the Bosonic String

In this note, we construct a BRST invariant cubic vertex for massless fields of arbitrary mixed symmetry in flat space-time. The construction is based on the vertex given in bosonic Open String Field Theory. The algebra of gauge transformations is closed without any additional, higher than cubic, couplings due to the presence of an infinite tower of massless fields. We briefly discuss the generalization of this result to a curved space-time and other possible implications.Comment: Published Version; typos corrected, references added; (v3) Some typos corrected and a minor clarification about eq. (3.29

Outlook for detection of GW inspirals by GRB-triggered searches in the Advanced detector era

Short, hard gamma-ray bursts (GRBs) are believed to originate from the coalescence of two neutron stars (NSs) or a NS and a black hole (BH). If this scenario is correct, then short GRBs will be accompanied by the emission of strong gravitational waves (GWs), detectable by GW observatories such as LIGO, Virgo, KAGRA, and LIGO-India. As compared with blind, all-sky, all-time GW searches, externally triggered searches for GW counterparts to short GRBs have the advantages of both significantly reduced detection threshold due to known time and sky location and enhanced GW amplitude because of face-on orientation. Based on the distribution of signal-to-noise ratios in candidate compact binary coalescence events in the most recent joint LIGO-Virgo data, our analytic estimates, and our Monte Carlo simulations, we find an effective sensitive volume for GRB-triggered searches that is about 2 times greater than for an all-sky, all-time search. For NS-NS systems, a jet angle of 20 degrees, a gamma-ray satellite field of view of 10% of the sky, and priors with generally precessing spin, this doubles the number of NS-NS short-GRB and NS-BH short-GRB associations, to ~3-4% of all detections of NS-NSs and NS-BHs. We also investigate the power of tests for statistical excesses in lists of subthreshold events, and show that these are unlikely to reveal a subthreshold population until finding GW associations to short GRBs is already routine. Finally, we provide useful formulas for calculating the prior distribution of GW amplitudes from a compact binary coalescence, for a given GW detector network and given sky location.Comment: 14 pages, 4 figures, published in PRD; this version includes changes in final copyedited articl

Economic integration, regional structural change and cohesion in the EU new member-states

The European economic landscape has changed dramatically during the last decade, following the collapse of the bi-polar world. The parallel and interacting processes of economic integration and transition are the driving forces of these changes. In this context, the EU new member-states (including the candidate countries of Bulgaria and Romania) have experienced, often forcefully and painfully, the impact of these processes as a pre-condition for catch-up and integration with the prosperous EU-15 countries. Being still in progress, these processes have altered the intraregional division of labor, affecting the patterns of regional specialization and industrial concentration and increasing the level of interregional competition and inequalities, in a newly emerged internationalized environment. The extent and the impact of these changes, however, are still issues of major scientific dialogue and concern, with many unknown parameters. The need for this first period of transition and economic integration (decade of 90s) to be re-evaluated is evident concerning the mobility of economic activities and possible re-location of industries, the behaviour of the individual regions, the dynamics of regional discrepancies and the stability of the territorial structures. The overall scientific objective of this paper is to identify and explain in a cross-country and comparative analysis the structural industrial patterns in the area of EU new member-states bringing together the findings and reports of the scientific bibliography. Furthermore, a static and dynamic analysis takes place in order to uncover in more depth the possible relation between economic integration, regional structural change and cohesion in these countries. To this direction, a number of research questions are addressed: What is the impact of economic integration to the evolution of regional industrial patterns? Have advanced and lagging-behind regions developed similar or different types of specialization? What is their mix of activities? Over time, do they become more similar or dissimilar? Have metropolitan regions the same mix of activities with peripheral and border regions? Do their economic structures become more similar or dissimilar over time? Are there particular types of structural change more closely related to strong growth performance? The main part of the analysis is conducted on a basis of employment data, as a proxy for industrial structures in NUTS III spatial level, disaggregated by manufacturing branches according to NACE rev.1 two-digit classification. Emphasis is given to the countries of Bulgaria, Romania, Slovenia, Hungary and Estonia due to lack of statistical information (regional-structural figures) for the other countries under research. However, despite this shortcoming, the country sample of our analysis can be considered representative of the whole area since it covers all its parts i.e. Southeastern Europe–Balkans (Bulgaria, Romania), Central Europe (Slovenia, Hungary), Eastern Europe–Baltic (Estonia). The research covers the period between 1990 and 1999, a period of extreme significance since it includes both the shocks and the upsets of the early transition (sub-period 1991–1995) and the recent, more independent, trends (1995–1999). The reported findings and conclusions of this research may be a valuable basis for the understanding of the impact of economic integration on regional structure change and cohesion and, as a result, be the basis for the discussion of the appropriate policies of cohesion in the enlarged EU-27.

Peripherality and Integration: Industrial Growth and Decline in the Greek Regions

An empirical model has been deployed to account for regional industrial growth and performance in Greece’s post EU-accession period. The results obtained suggest that the effect of European integration on manufacturing has been rather adverse across Greek regions. Regions that are more industrialised, whose structure was more similar to the European average and which have been more exposed to European competition are those that have been more adversely affected. In contrast, higher diversity, higher presence of capital intensive sectors and higher tertiarisation of the regional economies were found to be beneficial to regional industrial growth and performance.

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