D-branes and Discrete Torsion II

We derive D-brane gauge theories for C^3/Z_n x Z_n orbifolds with discrete torsion and study the moduli space of a D-brane at a point. We show that, as suggested in previous work, closed string moduli do not fully resolve the singularity, but the resulting space -- containing n-1 conifold singularities -- is somewhat surprising. Fractional branes also have unusual properties. We also define an index which is the CFT analog of the intersection form in geometric compactification, and use this to show that the elementary D6-brane wrapped about T^6/Z_n x Z_n must have U(n) world-volume gauge symmetry.Comment: harvmac, 25 p

De novo Development and Characterization of Tetranucleotide Microsatellite Loci Markers from a Southeastern Population of the House Finch (Haemorhous mexicanus)

Microsatellites are short tandem repeats (e.g. TAGATAGA) of base pairs in a species’ genome. High mutation rates in these regions produce variation in the number of repeats across individuals that can be utilized to study patterns of population- and landscape-level genetics and to determine parentage genetically. In this project our objective was to develop microsatellite markers for the House Finch, Haemorhous mexicanus. This species has become one of the most well-studied species of songbirds due to its unique geographical, evolutionary, and epidemiological history. Using mist-nets we captured birds on the Arkansas Tech University campus and collected blood samples to obtain genomic DNA. Samples were processed in The Field Museum’s Pritzker Laboratory for Molecular Systematics and Evolution, where we fragmented genomic DNA and isolated fragments that contained potential microsatellites using specially designed biotin labelled probes. These DNA fragments were transformed into competent E. coli cells which were then PCR-amplified and Sanger sequenced. After sequencing DNA fragments from approximately 500 E. coli colonies, we designed and characterized a set of 13 tetranucleotide microsatellite loci. The average number of alleles and heterozygosity found in 12 individuals from Arkansas was 8.69 and 0.80, respectively. This finalized set of microsatellites can be utilized by researchers to determine parentage and characterize genetic differences across House Finch populations

Dual WDVV Equations in N=2 Supersymmetric Yang-Mills Theory

This paper studies the dual form of Witten-Dijkgraaf-Verlinde-Verlinde (WDVV) equations in N=2 supersymmetric Yang-Mills theory by applying a duality transformation to WDVV equations. The dual WDVV equations called in this paper are non-linear differential equations satisfied by dual prepotential and are found to have the same form with the original WDVV equations. However, in contrast with the case of weak coupling calculus, the perturbative part of dual prepotential itself does not satisfy the dual WDVV equations. Nevertheless, it is possible to show that the non-perturbative part of dual prepotential can be determined from dual WDVV equations, provided the perturbative part is given. As an example, the SU(4) case is presented. The non-perturbative dual prepotential derived in this way is consistent to the dual prepotential obtained by D'Hoker and Phong.Comment: misprints are corrected, revtex, 10 page

Effects of Hypohydration on Work Performance and Tolerance to plus Gz Acceleration in Man

Hypohydration effects on work performance and tolerance to acceleration stress in ma

Wind loads on ground-based telescopes

One of the factors that can influence the performance of large optical telescopes is the vibration of the telescope structure due to unsteady wind inside the telescope enclosure. Estimating the resulting degradation in image quality has been difficult because of the relatively poor understanding of the flow characteristics. Significant progress has recently been made, informed by measurements in existing observatories, wind-tunnel tests, and computational fluid dynamic analyses. We combine the information from these sources to summarize the relevant wind characteristics and enable a model of the dynamic wind loads on a telescope structure within an enclosure. The amplitude, temporal spectrum, and spatial distribution of wind disturbances are defined as a function of relevant design parameters, providing a significant improvement in our understanding of an important design issue

Longitudinal phase space manipulation in energy recovering linac-driven free-electron lasers

Energy recovering an electron beam after it has participated in a free-electron laser (FEL) interaction can be quite challenging because of the substantial FEL-induced energy spread and the energy anti-damping that occurs during deceleration. In the Jefferson Lab infrared FEL driver-accelerator, such an energy recovery scheme was implemented by properly matching the longitudinal phase space throughout the recirculation transport by employing the so-called energy compression scheme. In the present paper,after presenting a single-particle dynamics approach of the method used to energy-recover the electron beam, we report on experimental validation of the method obtained by measurements of the so-called "compression efficiency" and "momentum compaction" lattice transfer maps at different locations in the recirculation transport line. We also compare these measurements with numerical tracking simulations.Comment: 31 pages, 13 figures, submitted to Phys. Rev. Special Topics A&

Thermal radiation of various gravitational backgrounds

We present a simple and general procedure for calculating the thermal radiation coming from any stationary metric. The physical picture is that the radiation arises as the quasi--classical tunneling of particles through a gravitational barrier. We show that our procedure can reproduce the results of Hawking and Unruh radiation. We also show that under certain kinds of coordinate transformations the temperature of the thermal radiation will change in the case of the Schwarzschild black holes. In addition we apply our procedure to a rotating/orbiting system and show that in this case there is no radiation, which has experimental implications for the polarization of particles in circular accelerators.Comment: 6 pages revtex, added references, publication version. To be published IJMP

Casimir interactions in Ising strips with boundary fields: exact results

An exact statistical mechanical derivation is given of the critical Casimir forces for Ising strips with arbitrary surface fields applied to edges. Our results show that the strength as well as the sign of the force can be controled by varying the temperature or the fields. An interpretation of the results is given in terms of a linked cluster expansion. This suggests a systematic approach for deriving the critical Casimir force which can be used in more general models.Comment: 10 pages, 4 figure

Cosmic D--term Strings as Wrapped D3 Branes

We describe cosmic D--term strings as D3 branes wrapped on a resolved conifold. The matter content that gives rise to D--term strings is shown to describe the world--volume theory of a space--filling D3 brane transverse to the conifold which itself is a wrapped D5 brane. We show that, in this brane theory, the tension of the wrapped D3 brane mathces that of the D--term string. We argue that there is a new type of cosmic string which arises from fractional D1 branes on the world--volume of a fractional D3 brane.Comment: 13 pages in phyzzx.tex; eq. (17) corrected, other minor corrections; v3: more minor correction