Level-Spacing Distributions and the Bessel Kernel

The level spacing distributions which arise when one rescales the Laguerre or Jacobi ensembles of hermitian matrices is studied. These distributions are expressible in terms of a Fredholm determinant of an integral operator whose kernel is expressible in terms of Bessel functions of order $\alpha$. We derive a system of partial differential equations associated with the logarithmic derivative of this Fredholm determinant when the underlying domain is a union of intervals. In the case of a single interval this Fredholm determinant is a Painleve tau function.Comment: 18 pages, resubmitted to make postscript compatible, no changes to manuscript conten

Structural and dielectric properties of Sr2_{2}TiO4_{4} from first principles

We have investigated the structural and dielectric properties of Sr$_{2}$TiO$_{4}$,the first member of the Sr$_{n+1}$Ti$_{n}$O$_{3n+1}$ Ruddlesden-Popper series, within density functional theory. Motivated by recent work in which thin films of Sr$_{2}$TiO$_{4}$ were grown by molecular beam epitaxy (MBE) on SrTiO$_{3}$ substrates, the in-plane lattice parameter was fixed to the theoretically optimized lattice constant of cubic SrTiO$_{3}$ (n=$\infty$), while the out-of-plane lattice parameter and the internal structural parameters were relaxed. The fully relaxed structure was also investigated. Density functional perturbation theory was used to calculate the zone-center phonon frequencies, Born effective charges, and the electronic dielectric permittivity tensor. A detailed study of the contribution of individual infrared-active modes to the static dielectric permittivity tensor was performed. The calculated Raman and infrared phonon frequencies were found to be in agreement with experiment where available. Comparisons of the calculated static dielectric permittivity with experiments on both ceramic powders and epitaxial thin films are discussed.Comment: 11 pages, 1 figure, 8 tables, submitted to Phys. Rev.

Oxygen isotopic constraints on the origin and parent bodies of eucrites, diogenites, and howardites

A few eucrites have anomalous oxygen isotopic compositions. To help understand their origin and identify additional samples, we have analyzed the oxygen isotopic compositions of 18 eucrites and four diogenites. Except for five eucrites, these meteorites have ?17O values that lie within 2 of their mean value viz., -0.242±0.016', consistent with igneous isotopic homogenization of Vesta. The five exceptional eucrites–NWA 1240, Pasamonte (both clast and matrix samples), PCA 91007, A-881394, and Ibitira–have ?17O values that lie respectively 4?, 5?, 5?, 15?, and 21 away from this mean value. NWA 1240 has a ?18O value that is 5? below the mean eucrite value. Four of the five outliers are unbrecciated and unshocked basaltic eucrites, like NWA 011, the first eucrite found to have an anomalous oxygen isotopic composition. The fifth outlier, Pasamonte, is composed almost entirely of unequilibrated basaltic clasts. Published chemical data for the six eucrites with anomalous oxygen isotopic compositions (including NWA 011) exclude contamination by chondritic projectiles as a source of the oxygen anomalies. Only NWA 011 has an anomalous Fe/Mn ratio, but several anomalous eucrites have exceptional Na, Ti, or Cr concentrations. We infer that the six anomalous eucrites are probably derived from five distinct Vesta-like parent bodies (Pasamonte and PCA 91007 could come from one body). These anomalous eucrites, like many unbrecciated eucrites from Vesta, are probably deficient in brecciation and shock effects because they were sequestered in small asteroids (~10 km diameter) during the Late Heavy Bombardment following ejection from Vesta-like bodies. The preservation of Vesta's crust and the lack of deeply buried samples from the hypothesized Vesta-like bodies are consistent with the removal of these bodies from the asteroid belt by gravitational perturbations from planets and protoplanets, rather than by collisonal grinding

Security trumps drug control: How securitization explains drug policy paradoxes in Thailand and Vietnam

This paper investigates the paradoxes inherent in Thai and Vietnamese drug policies. The two countries have much in common. Both are ultra-prohibitionist states which employ repressive policies to contain drug markets. Their policies have, however, diverged in two key areas: opium suppression and harm reduction. Thailand implemented an effective intervention to suppress opium farming centred upon alternative development, whereas Vietnam suppressed opium production through coercive negotiation with nominal alternative development. Vietnam has embraced elements of harm reduction, whereas Thailand has been slow to implement harm reduction policies. This paper hypothesises that these two differences are largely a product of their perceived relationship to security. The two cases demonstrate how once an issue is securitized the ultra-prohibitionist rules of the game can be broken to allow for more humane and pragmatic policies

Mechanical properties of several products from a single heat of type 304 stainless steel

From winter meeting of American Society of Mechanical Engineers; Detroit, Michigan, USA (11 Nov 1973). Tensile and stress-rupture tests were run on several products from a 90-ton heat of type 304 stainless steel. The yield stress of the products in the as-received condition varied from 26,500 to 57,200 psi at 75 deg F. There were significant differences between the strengths of various products and considerable variation for a single product due to nonuniform residual cold work. Reannealing 0.5 h at 2000 deg F resulted in yield stresses in the 25,000 to 27,000 psi range; only the properties of the hot- reduced tubing fell below this range. At a test temperature of 1100 deg F, the as-received products had yield stresses from 14,800 to 35,500 psi. Reannealing caused the yield stresses of all but three products to fall in the range 10,200 to 11,700 psi. Stress-rupture tests at 1100 deg F on the reannealed products did not reveal significant variation in properties. (auth

The Role of Interaction Quality and Switching Costs in Premium Banking Services

Purpose - This paper re-examines the commitment-trust model (Morgan and Hunt, 1994) in the context of premium banking services. Inline with Toncar and Munch (2010) we seek to develop an extension to the model because of the need to encapsulate contextual variables that constrain the link between the core relationship marketing constructs of trust and commitment.Design/methodology/approach - A series of qualitative interviews were administered with bank relationship managers and premium banking customers. This enabled the concurrent consideration of both bank and customer views that helped to establish converging lines of thought within the bank-customer relationship.Findings - Our findings provided evidence of the commitment-trust link, and in particular continuance-based commitment, within the context of premium banking relationships. By triangulating our findings with current thinking in relationship marketing literature we present propositions for interaction quality and switching costs to be salient moderators between trust and commitment in this premium segment. A conceptual model that outlines the interplay between these four constructs is offered.Originality/value - Few have examined the commitment-trust link in light of moderator variables within retail banking services, and this research is the first to examine this specifically in the premium banking segment where customers are likely to be financially savvier and less knowledge dependent. This research therefore takes the first step in developing an extension to the commitment-trust model for this segment, and forms the basis for further empirical research to examine the specific impact of interaction quality and switching costs, particularly in relation to continuance-based commitment

Differential species-specific ectoparasitic mite intensities in two intimately coexisting sibling bat species: resource-mediated host attractiveness or parasite specialization?

1. The mechanisms underlying host choice strategies by parasites remain poorly understood. We address two main questions: (i) do parasites prefer vulnerable or well-fed hosts, and (ii) to what extent is a parasite species specialized towards a given host species? 2. To answer these questions, we investigated, both in the field and in the lab, a host-parasite system comprising one ectoparasitic mite (Spinturnix myoti) and its major hosts, two sibling species of bats (Myotis myotis and M blythii), which coexist intimately in colonial nursery roosts. We exploited the close physical associations between host species in colonial roosts as well as naturally occurring annual variation in food abundance to investigate the relationships between parasite intensities and (i) host species and (ii) individual nutritional status. 3. Although horizontal transmission of parasites was facilitated by the intimate aggregation of bats within their colonial clusters, we found significant interspecific differences in degree of infestation throughout the 6 years of the study, with M. myotis always more heavily parasitized than M. blythii. This pattern was replicated in a laboratory experiment in which any species-specific resistance induced by exploitation of different trophic niches in nature was removed. 4. Within both host species, S. myoti showed a clear preference for individuals with higher nutritional status. In years with high resource abundance, both bat hosts harboured more parasites than in low-resource years, although the relative difference in parasite burden across species was maintained. This pattern of host choice was also replicated in the laboratory. When offered a choice, parasites always colonized better-fed individuals. 5. These results show first that host specialization in our study system occurred. Second, immediate parasite choice clearly operated towards the selection of hosts in good nutritional state