Quark-gluon vertex dressing and meson masses beyond ladder-rainbow truncation

We include a generalized infinite class of quark-gluon vertex dressing diagrams in a study of how dynamics beyond the ladder-rainbow truncation influences the Bethe-Salpeter description of light quark pseudoscalar and vector mesons. The diagrammatic specification of the vertex is mapped into a corresponding specification of the Bethe-Salpeter kernel, which preserves chiral symmetry. This study adopts the algebraic format afforded by the simple interaction kernel used in previous work on this topic. The new feature of the present work is that in every diagram summed for the vertex and the corresponding Bethe-Salpeter kernel, each quark-gluon vertex is required to be the self-consistent vertex solution. We also adopt from previous work the effective accounting for the role of the explicitly non-Abelian three gluon coupling in a global manner through one parameter determined from recent lattice-QCD data for the vertex. With the more consistent vertex used here, the error in ladder-rainbow truncation for vector mesons is never more than 10% as the current quark mass is varied from the u/d region to the b region.Comment: 15 pages, 12 figure

Measuring the use of information and communication technologies (ICTs) in the classroom

In 2003, the ICT Curriculum Integration Performance Measurement Instrument was developed from an extensive review of the contemporary international and Australian research pertaining to the definition and measurement of ICT curriculum integration in classrooms (Proctor, Watson, & Finger, 2003). The 45-item instrument that resulted was based on theories and methodologies identified by the literature review. This paper describes psychometric results from a large-scale evaluation of the instrument subsequently conducted, as recommended by Proctor, Watson and Finger (2003). The resultant 20-item, two-factor instrument, now called Learning With ICTs: Measuring ICT Use in the Curriculum is both statistically and theoretically robust. This paper should be read in association with the original paper published in Computers in the Schools (Proctor, Watson & Finger, 2003) that described in detail the theoretical framework underpinning the development of the instrument

THE ECONOMICS OF RIPARIAN MANAGEMENT: A LITERATURE REVIEW

Resource /Energy Economics and Policy,

Masticatory biomechanics in the rabbit : a multi-body dynamics analysis

Acknowledgement We thank Sue Taft (University of Hull) for the µCT-scanning of the rabbit specimen used in this study. We also thank Raphaël Cornette, Jacques Bonnin, Laurent Dufresne, and l'Amicale des Chasseurs Trappistes (ACT) for providing permission and helping us capture the rabbits used for the in vivo bite force measurements at la Réserve Naturelle Nationale de St Quentin en Yvelines, France.Peer reviewedPublisher PD

Tail Separation and Density Effects on the Underwater Trajectory of the JDAM

Ninth Monterey International Symposium on Technology and Mine Problems, Society for Counter-Ordnance TechnologyThe Navy is in need of an organic, inexpensive, swift method to neutralize or sweep waterborne mines. This paper presents an alternative to current mine countermeasure technologies that fulfill this criteria - the use of the Joint Direct Attack Munition (JDAM) to clear a minefield. Our experimental and modeling study strongly suggest high efficiency of the JABS for mine clearance in the very shallow water (depth less than 12.2 m)

Detection of Earth-like Planets Using Apodized Telescopes

The mission of NASA's Terrestrial Planet Finder (TPF) is to find Earth-like planets orbiting other stars and characterize the atmospheres of these planets using spectroscopy. Because of the enormous brightness ratio between the star and the reflected light from the planet, techniques must be found to reduce the brightness of the star. The current favorite approach to doing this is with interferometry: interfering the light from two or more separated telescopes with a $\pi$ phase shift, nulling out the starlight. While this technique can, in principle, achieve the required dynamic range, building a space interferometer that has the necessary characteristics poses immense technical difficulties. In this paper, we suggest a much simpler approach to achieving the required dynamic range. By simply adjusting the transmissive shape of a telescope aperture, the intensity in large regions around the stellar image can be reduced nearly to zero. This approach could lead to construction of a TPF using conventional technologies, requiring space optics on a much smaller scale than the current TPF approach.Comment: Accepted for publication in ApJ Letters, 9 pages, 6 figure

Neutrino oscillations in matter of varying density

We consider two-family neutrino oscillations in a medium of continuously-varying density as a limit of the process in a series of constant-density layers. We construct analytic expressions for the conversion amplitude at high energies within a medium with a density profile that is piecewise linear. We compare some cases to understand the type of effects that depend on the order of the material traversed by a neutrino beam.Comment: 10 page

Helium in natal HII regions: the origin of the X-ray absorption in gamma-ray burst afterglows

Soft X-ray absorption in excess of Galactic is observed in the afterglows of most gamma-ray bursts (GRBs), but the correct solution to its origin has not been arrived at after more than a decade of work, preventing its use as a powerful diagnostic tool. We resolve this long-standing problem and find that He in the GRB's host HII region is responsible for most of the absorption. We show that the X-ray absorbing column density (N_Hx) is correlated with both the neutral gas column density and with the optical afterglow extinction (Av). This correlation explains the connection between dark bursts and bursts with high N_Hx values. From these correlations we exclude an origin of the X-ray absorption which is not related to the host galaxy, i.e. the intergalactic medium or intervening absorbers are not responsible. We find that the correlation with the dust column has a strong redshift evolution, whereas the correlation with the neutral gas does not. From this we conclude that the column density of the X-ray absorption is correlated with the total gas column density in the host galaxy rather than the metal column density, in spite of the fact that X-ray absorption is typically dominated by metals. The strong redshift evolution of N_Hx/Av is thus a reflection of the cosmic metallicity evolution of star-forming galaxies. We conclude that the absorption of X-rays in GRB afterglows is caused by He in the HII region hosting the GRB. While dust is destroyed and metals are stripped of all of their electrons by the GRB to great distances, the abundance of He saturates the He-ionising UV continuum much closer to the GRB, allowing it to remain in the neutral or singly-ionised state. Helium X-ray absorption explains the correlation with total gas, the lack of strong evolution with redshift as well as the absence of dust, metal or hydrogen absorption features in the optical-UV spectra.Comment: 10 pages, 4 figures, submitted to Ap

Epidemiology of imported cutaneous leishmaniasis at the Hospital for Tropical Diseases, London, United Kingdom: use of polymerase chain reaction to identify the species.

This study reviewed all patients diagnosed with imported cutaneous leishmaniasis (CL) at the Hospital for Tropical Diseases in London, United Kingdom, over an 11-year period. Diagnostic and epidemiologic information was collected prospectively for all patients with imported CL to this hospital during 1998-2009. A total of 223 patients were given a diagnosis of CL. Ninety patients were diagnosed with Old World CL, which was caused most commonly by Leishmania donovani complex (n = 20). A total of 71% were tourists to the Mediterranean region, 36% were migrants or visiting friends and relatives, and 17% were soldiers. One hundred thirty-three patients were given a diagnosis of New World CL. The Leishmania subgenus Viannia caused 97 of these cases; 44% of these were in backpackers and 29% were in soldiers. Polymerase chain reaction was more sensitive and faster for detecting Leishmania DNA (86% for Old World CL and 96% for New World CL) than culture. This is the largest study of imported leishmaniasis, and demonstrates that tourists to the Mediterranean and backpackers in Central and South America are at risk for this disease