A "hybrid plane" with spin-orbit interaction

In this paper we attempt to reconstruct one of the last projects of Volodya Geyler which remained unfinished. We study motion of a quantum particle in the plane to which a halfline lead is attached assuming that the particle has spin $\frac12$ and the plane component of the Hamiltonian contains a spin-orbit interaction of either Rashba or Dresselhaus type. We construct the class of admissible Hamiltonians and derive an explicit expression for the Green function applying it to the scattering in such a system.Comment: LaTeX, 9 pages; in memoriam Vladimir A. Geyler (1943-2007

The leafage of a chordal graph

The leafage l(G) of a chordal graph G is the minimum number of leaves of a tree in which G has an intersection representation by subtrees. We obtain upper and lower bounds on l(G) and compute it on special classes. The maximum of l(G) on n-vertex graphs is n - lg n - (1/2) lg lg n + O(1). The proper leafage l*(G) is the minimum number of leaves when no subtree may contain another; we obtain upper and lower bounds on l*(G). Leafage equals proper leafage on claw-free chordal graphs. We use asteroidal sets and structural properties of chordal graphs.Comment: 19 pages, 3 figure

An Economic Theory of Glass Ceiling

In the 'glass ceiling' debate there appear to be two strongly held and opposing interpretations of the evidence, one suggesting it is really the result of gender differences and the other that there is discrimination by gender. This paper provides an economic theory of the glass ceiling and one of the main insights of our analysis is that in some real sense these two interpretations are not in conflict with each other. The glass ceiling emerges as an equilibrium phenomenon when firms compete à la Bertrand even though employers know that offering women the same contract as men would be sufficient to erase all differences among promoted workers. The model also provides new insights into anti-discrimination policy measures. (Updated from working paper 07/183)glass ceilings, promotions, career options

A lens-coupled scintillation counter in cryogenic environment

In this work we present an elegant solution for a scintillation counter to be integrated into a cryogenic system. Its distinguishing feature is the absence of a continuous light guide coupling the scintillation and the photodetector parts, operating at cryogenic and room temperatures respectively. The prototype detector consists of a plastic scintillator with glued-in wavelength-shifting fiber located inside a cryostat, a Geiger-mode Avalanche Photodiode (G-APD) outside the cryostat, and a lens system guiding the scintillation light re-emitted by the fiber to the G-APD through optical windows in the cryostat shields. With a 0.8mm diameter multiclad fiber and a 1mm active area G-APD the coupling efficiency of the "lens light guide" is about 50%. A reliable performance of the detector down to 3K is demonstrated.Comment: 14 pages, 11 figure

An Economic Theory of the Glass Ceiling

The glass ceiling is one of the most controversial and emotive aspects of employment in organisations. This paper provides a model of the glass ceiling that exhibits the following features that are frequently thought to characterise the problem: (i) there is a lower number of female employees in higher positions, (ii) women have to work harder than men to obtain equivalent jobs, (iii) women are then paid less than men when promoted, and (iv) some organisations are more female friendly than others. These features emerge as an equilibrium phenomenon, when identical firms compete in "Bertrand-like" fashion. Furthermore, they also occur even when offering women the same contract as men in higher positions would be sufficient to ensure that women in those positions would always prefer permanent career over non-market alternatives.Glass Ceiling, Promotions, Career Options

Quantum MHV diagrams

Over the past two years, the use of on-shell techniques has deepened our understanding of the S-matrix of gauge theories and led to the calculation of many new scattering amplitudes. In these notes we review a particular on-shell method developed recently, the quantum MHV diagrams, and discuss applications to one-loop amplitudes. Furthermore, we briefly discuss the application of D-dimensional generalised unitarity to the calculation of scattering amplitudes in non-supersymmetric Yang-Mills

The stochastic reflection problem on an infinite dimensional convex set and BV functions in a Gelfand triple

In this paper, we introduce a definition of BV functions in a Gelfand triple which is an extension of the definition of BV functions in [2] by using Dirichlet form theory. By this definition, we can consider the stochastic reflection problem associated with a self-adjoint operator $A$ and a cylindrical Wiener process on a convex set $\Gamma$ in a Hilbert space $H$. We prove the existence and uniqueness of a strong solution of this problem when $\Gamma$ is a regular convex set. The result is also extended to the non-symmetric case. Finally, we extend our results to the case when $\Gamma=K_\alpha$, where $K_\alpha={f\in L^2 (0,1)|f\geq -\alpha},\alpha\geq0$

The Humoral Immunity Response of Dog Vaccinated with Oral Sag2 and Parenteral Rabisin and Rabivet Supra92

This research aims to determine whether SAG2 oral vaccine induced antibody response as high as that of parenteral vaccine (Rabisin and Rabivet Supra 92). The experimental design applied was randomized pre and post control group design with 4 treatments (oral SAG2 vaccine, parenteral rabisin, parenteral Rabivet Supra 92 and control without vaccination) and with 9 replication. As many as 36 kampung dogs used and the anti rabies antibody was determined by enzyme-linked immunosorbent assay (ELISA) at day 0, 21, 56, 84, 119, and 147 post vaccination. The antibody titer induced by oral SAG2 vaccine raised more slowly but persisted longer than parenteral vaccine. On day 21 after vaccination, the average antibody titers induced by oral SAG2 vaccines (0.501 IU/ml) was still significantly lower than those induced by parenteral Rabisin (3.504 IU/ml) and Rabivet Supra92 (2.545 IU/ml). However, by day 119 after vaccination the average antibody titer induced by SAG2 oral vaccine (0.889 IU/ml) was significantly higher (p <0.05) as compared to those of parenteral Rabisin (0.625 IU/ml) and Rabivet Supra 92 (0.223 IU/ml). The antibody response induced by SAG2 oral vaccine appears to persist longer than parenteral vaccines and it can therefore be used as an alternative vaccine to combat rabies in animals, especially for dogs kept in free range

The cooling rate of neutron stars after thermonuclear shell flashes

Thermonuclear shell flashes on neutron stars are detected as bright X-ray bursts. Traditionally, their decay is modeled with an exponential function. However, this is not what theory predicts. The expected functional form for luminosities below the Eddington limit, at times when there is no significant nuclear burning, is a power law. We tested the exponential and power-law functional forms against the best data available: bursts measured with the high-throughput Proportional Counter Array (PCA) on board the Rossi X-ray Timing Explorer. We selected a sample of 35 'clean' and ordinary (i.e., shorter than a few minutes) bursts from 14 different neutron stars that 1) show a large dynamic range in luminosity, 2) are the least affected by disturbances by the accretion disk and 3) lack prolonged nuclear burning through the rp-process. We find indeed that for every burst a power law is a better description than an exponential function. We also find that the decay index is steep, 1.8 on average, and different for every burst. This may be explained by contributions from degenerate electrons and photons to the specific heat capacity of the ignited layer and by deviations from the Stefan-Boltzmann law due to changes in the opacity with density and temperature. Detailed verification of this explanation yields inconclusive results. While the values for the decay index are consistent, changes of it with the burst time scale, as a proxy of ignition depth, and with time are not supported by model calculations.Comment: 10 pages, 7 figures, recommended for publication in A&