The Matsubara-Fradkin Thermodynamical Quantization of Podolsky Electrodynamics

In this work we apply the Matsubara-Fradkin formalism and the Nakanishi's auxiliary field method to the quantization of the Podolsky electrodynamics in thermodynamic equilibrium. This approach allows us to write consistently the path integral representation for the partition function of gauge theories in a simple manner. Furthermore, we find the Dyson-Schwinger-Fradkin equations and the Ward-Fradkin-Takahashi identities for the Podolsky theory. We also write the most general form for the polarization tensor in thermodynamic equilibrium.Comment: Submitted to Physical Review

Optical microrheology using rotating laser-trapped particles

We demonstrate an optical system that can apply and accurately measure the torque exerted by the trapping beam on a rotating birefringent probe particle. This allows the viscosity and surface effects within liquid media to be measured quantitatively on a micron-size scale using a trapped rotating spherical probe particle. We use the system to measure the viscosity inside a prototype cellular structure.Comment: 5 pages, 4 figures. v2: bibliographic details, minor text correction

Degenerate flag varieties: moment graphs and Schr\"oder numbers

We study geometric and combinatorial properties of the degenerate flag varieties of type A. These varieties are acted upon by the automorphism group of a certain representation of a type A quiver, containing a maximal torus T. Using the group action, we describe the moment graphs, encoding the zero- and one-dimensional T-orbits. We also study the smooth and singular loci of the degenerate flag varieties. We show that the Euler characteristic of the smooth locus is equal to the large Schr\"oder number and the Poincar\'e polynomial is given by a natural statistics counting the number of diagonal steps in a Schr\"oder path. As an application we obtain a new combinatorial description of the large and small Schr\"oder numbers and their q-analogues.Comment: 25 page

Where are the beachmasters? Unexpectedly weak polygyny among southern elephant seals on a South Shetland Island

Intraspecific variation in animal mating systems can have important implications for ecological, evolutionary and demographic processes in wild populations. For example, patterns of mating can impact social structure, dispersal, effective population size and inbreeding. However, few species have been studied in sufficient detail to elucidate mating system plasticity and its dependence on ecological and demographic factors. Southern elephant seals (Mirounga leonina) have long been regarded as a textbook example of a polygynous mating system, with dominant ‘beachmaster’ males controlling harems of up to several hundred females. However, behavioural and genetic studies have uncovered appreciable geographic variation in the strength of polygyny among elephant seal populations. We, therefore, used molecular parentage analysis to investigate patterns of parentage in a small satellite colony of elephant seals at the South Shetland Islands. We hypothesised that dominant males would be able to successfully monopolise the relatively small numbers of females present in the colony, leading to relatively high levels of polygyny. A total of 424 individuals (comprising 33 adult males, 101 adult females and 290 pups) sampled over 8 years were genotyped at 20 microsatellites and reproductive success was analysed by genetically assigning parents. Paternity could only be assigned to 31 pups (10.7%), despite our panel of genetic markers being highly informative and the genotyping error rate being very low. The strength of inferred polygyny was weak in comparison to previous genetic studies of the same species, with the most successful male fathering only seven pups over the entire course of our study. Our results show that, even in a species long regarded as a model for extreme polygyny, male reproductive skew can vary substantially among populations

Information sharing and credit : firm-level evidence from transition countries

We investigate whether information sharing among banks has affected credit market performance in the transition countries of Eastern Europe and the former Soviet Union, using a large sample of firm-level data. Our estimates show that information sharing is associated with improved availability and lower cost of credit to firms. This correlation is stronger for opaque firms than transparent ones and stronger in countries with weak legal environments than in those with strong legal environments. In cross-sectional estimates, we control for variation in country-level aggregate variables that may affect credit, by examining the differential impact of information sharing across firm types. In panel estimates, we also control for the presence of unobserved heterogeneity at the firm level, as well as for changes in macroeconomic variables and the legal environment

Podolsky Electromagnetism at Finite Temperature: Implications on Stefan-Boltzmann Law

In this work we study Podolsky electromagnetism in thermodynamic equilibrium. We show that a Podolsky mass-dependent modification to the Stefan-Boltzmann law is induced and we use experimental data to limit the possible values for this free parameter.Comment: 13 pages, submitted to Physical Review

Projectile Δ\Delta and target-Roper excitation in the p (d, d')X reaction

In this paper we compare a model that contains the mechanisms of $\Delta$ excitation in the projectile and Roper excitation in the target with experimental data from two (d, d') experiments on a proton target. The agreement of the theory with the experiment is fair for the data taken at T_d = 2.3 GeV. The $\Delta$ excitation in the projectile is predicted close to the observed energy with the correct width. The theory, however, underpredicts by about 40% the cross sections measured at T_d = 1.6 GeV at angles where the cross section has fallen by about two orders of magnitude. The analysis done here allows to extract an approximate strength for the excitation of the Roper [N^*(1440)] excitation and a qualitative agreement with the theoretical predictions is also found.Comment: 8 ps figure

Borrelia Lyme Group

Borreliaceae is a family of the phylum Spirochaetales and includes two genera, Borrelia and Cristispira genus. Borrelia genus is divided into three groups, namely Lyme group (LG), Echidna‐Reptile group (REPG) and Relapsing Fever group (RFG). All Borrelia species have an obligate parasitic lifestyle, as they depend on their hosts for most of their nutritional needs. Borreliæ are transmitted among vertebrate hosts by arthropod vectors (ticks and lice). Transtadial transmission within their carriers occurs for the Borreliæ RF Group, while this does not (or rarely occurs) for the Borreliæ Lyme Group. Phylogenetic data demonstrated that these two groups are genetically similar but distinct, forming independent clades sharing a common ancestor. In nature, the vectors of LB belong to the genus Ixodes spp. frequently found in the Northern Hemisphere, while the vectors of RF are usually the soft-ticks (Ornithodoros spp.). Borreliae share a unique genomic structure consisting of a single highly conserved linear chromosome and several linear and circular extrachromosomal plasmids which can vary widely between strains. In addition to Lyme and RF borreliosis, an intermediate group, called Echidna-Reptile borreliosis, has recently been identified. Lyme disease (LD) is caused by the spirochæte Borrelia burgdorferi sensu lato (s.l.) and transmitted to humans by the bite of a hard tick of the genus Ixodes, and LD reservoir are usually small rodents. LD is present in America, Eurasia, Africa, while its presence in Australia is not yet well documented. Not all Borreliæ Lyme Groups cause this disease in humans. Of the 23 Borreliæ burgdorferi s.l. currently known only 9 have been identified in human infection, namely Borrelia burgdorferi sensu stricto, B. afzelii, B. bavarensis, B. bissettii, B. garinii, B. lusitaniae, B. spielmani, B. valaisiana, and B. mayonii. LD is an organotropic infection, but there is also a spirochætemic form, caused by Borrelia mayonii, which gives fever similarly to the Borreliosis RF Group. A third variant of LD is Baggio-Yoshinari Syndrome (BYS), which is transmitted by another hard tick, Amblyomma cajennense. This Borrelia has not been isolated in culture, therefore its membership in the Lyme Group is not yet proven. All three of these Sub-Groups can manifest early with erythema migrans. Clinical features of LD are wide and variable, with clinical manifestations linked to distinct tissue tropisms of specific Borrelia burgdorferi s.l. genospecies. The early infection is localized and, in the absence of treatment, the spirochete can spread. The organs most frequently involved are skin, joints, muscles, nervous system, heart and eyes. B. burgdorferi s.s. is more often associated with Lyme arthritis, Borrelia garinii with neuroborreliosis and B. afzelii with acrodermatitis chronica atrophicans

THE COST STRUCTURE OF MICROFINANCE INSTITUTIONS IN EASTERN EUROPE AND CENTRAL ASIA

Microfinance institutions are important, particularly in developing countries, because they expand the frontier of financial intermediation by providing loans to those traditionally excluded from formal financial markets. This paper presents the first systematic statistical examination of the performance of MFIs operating in Eastern Europe and Central Asia. A cost function is estimated for MFIs in the region from 1999-2004. First, the presence of subsidies is found to be associated with higher MFI costs. When output is measured as the number of loans made, we find that MFIs become more efficient over time and that MFIs involved in the provision of group loans and loans to women have lower costs. However, when output is measured as volume of loans rather than their number, this last finding is reversed. This may be due to the fact that such loans are smaller in size; thus for a given volume more loans must be made.http://deepblue.lib.umich.edu/bitstream/2027.42/40195/3/wp809.pd