Plasticity in current-driven vortex lattices

We present a theoretical analysis of recent experiments on current-driven vortex dynamics in the Corbino disk geometry. This geometry introduces controlled spatial gradients in the driving force and allows the study of the onset of plasticity and tearing in clean vortex lattices. We describe plastic slip in terms of the stress-driven unbinding of dislocation pairs, which in turn contribute to the relaxation of the shear, yielding a nonlinear response. The steady state density of free dislocations induced by the applied stress is calculated as a function of the applied current and temperature. A criterion for the onset of plasticity at a radial location $r$ in the disk yields a temperature-dependent critical current that is in qualitative agreement with experiments.Comment: 11 pages, 4 figure

Weigh Station Bypassing

A Study was initiated in May of 1990 to investigate the problem of trucks bypassing or avoiding weigh/enforcement stations in Kentucky. A literature review identified two major studies (Wisconsin and Florida) on the subject, both of which are summarized in this report. In addition, a 1989, limited-scope study of truck bypassing of weigh stations in Kentucky was reviewed and summarized. The primary data collection effort for this study took place in the fall of 1990, centered around the Simpson County enforcement station on Interstate-55. Three potential bypass routes were identified. Automatic vehicle classification (AVC) and weight-in-motion (WIM) equipment was installed on 1-65 and on all three bypass routes. Data collection took place over a three-week period, with enforcement on the bypass routes during the second week. Significant conclusions of the study include: 1) While weigh station bypassing does occur in Kentucky, there was no indication of significant numbers of trucks modifying their route choices due to enforcement activity on the bypass routes; 2) Average truck weights and the percentage of trucks overweight are higher on bypass routes than on Interstate routes, but this is not primarily a result of bypassing activity; 3) The majority of trucks on bypass routes have legitimate reasons (in terms of origin or destination) to be on those routes; 4) A high percentage of trucks on bypass routes have violations, regardless of whether the trucks have a local origin/destination along the route; 5) The most common inspection violations on bypass routes are safety-related equipment violations, followed by driver violations; 6) Temporary enforcement efforts on bypass routes can be effective and can be self-supporting through citation revenues; 7) Due to accuracy limitations, high speed WIM data may not be appropriate for certain uses. The following recommendations were developed: 1) A statewide enforcement plan should be developed with increased emphasis on enforcement for non- Interstate routes; 2) Innovative options should be investigated to simplify or expedite weigh station operations; 3) Enforcement efforts on non-Interstate routes should be randomized and unpredictable and should include weighing of trucks; 4) Effectiveness measures should be developed and used to monitor non-Interstate enforcement efforts; 5) The accuracy of statewide WIM data should be assessed; 6) The potential for using statewide WIM data to identify problem areas and direct enforcement efforts should be explored, and a formal process should be established to foster this cooperative effort

Carbon Stars and other Luminous Stellar Populations in M33

The M33 galaxy is a nearby, relatively metal-poor, late-type spiral. Its proximity and almost face-on inclination means that it projects over a large area on the sky, making it an ideal candidate for wide-field CCD mosaic imaging. Photometry was obtained for more than 10^6 stars covering a 74' x 56' field centered on M33. Main sequence (MS), supergiant branch (SGB), red giant branch (RGB) and asymptotic giant branch (AGB) populations are identified and classified based on broad-band V and I photometry. Narrow-band filters are used to measure spectral features allowing the AGB population to be further divided into C and M-star types. The galactic structure of M33 is examined using star counts, colour-colour and colour-magnitude selected stellar populations. We use the C to M-star ratio to investigate the metallicity gradient in the disk of M33. The C/M-star ratio is found to increase and then flatten with increasing galactocentric radius in agreement with viscous disk formation models. The C-star luminosity function is found to be similar to M31 and the SMC, suggesting that C-stars should be useful distance indicators. The ``spectacular arcs of carbon stars'' in M33 postulated recently by Block et al. (2004) are found in our work to be simply an extension of M33's disk.Comment: 20 pages, 20 figures. Accepted for publication in The Astronomical Journa

Role of twin boundaries on the vortex dynamics in YBa2_2Cu3_3O7_7

By means of a novel technique of rotating the applied current we have directly measured the influence of twin boundaries on the vortex motion in a YBa$_2$Cu$_3$O$_7$ single crystal. The results indicate that the effect of twin planes on the vortex dynamics starts to develop below a certain temperature, being responsible for an anisotropic viscosity in the vortex liquid state and a guided motion in the solid state.Comment: 4 pages, 4 figure

A community-based intervention in middle schools to improve HPV vaccination and cervical cancer screening in Japan

Abstract Aim Japan has low rates of cervical cancer screening and Human papilloma virus (HPV) vaccination. This research examines the effectiveness of a family medicine resident-led, intervention in increasing knowledge about HPV and cervical cancer in middle school-girls and increasing knowledge and intention to have cervical cancer screening in their mothers. Methods We utilized a pre-test/post-test intervention design in three rural middle schools with 7th grade middle school-girls and their mothers. A school-based activity educated girls about HPV and cervical cancer. A home-based activity utilized a homework assignment for girls and their mothers. Pre/post intervention surveys were completed by the girls and their mothers. Major outcomes included changes in knowledge among girls and mothers and barriers to be screened for cervical cancer among mothers. Results Sixty-five students and sixty-three mothers completed the study. Two out five mothers were not in compliance with current screening recommendations. Identified barriers included: embarrassment (79%), poor access (56%), fear of having cancer (52%), and cervical cancer screening being an unknown procedure (46%). Forty-four percent of mothers deemed their daughters to be at risk for cervical cancer. Trusted sources of information included: doctors (97%), newspapers/television (89%), government (79%), the Internet (78%), and friends (62%). Student knowledge scores (7-point scale) improved significantly from pre- to post-intervention (4.8 vs. 5.9, p < 0.001). Knowledge scores (14-point scale) among mothers also significantly improved (11.7 vs. 12.0, p = 0.024). Conclusions These data suggest a community-based intervention on a sensitive topic by family medicine residents can be implemented in middle schools, can improve school-girls’ knowledge about HPV and cervical cancer, and can reach their mothers. Additional research could examine whether those intending to be screened receive screening and how to reach women who still resist screening.http://deepblue.lib.umich.edu/bitstream/2027.42/109452/1/12930_2014_Article_13.pd

J-type Carbon Stars in the Large Magellanic Cloud

A sample of 1497 carbon stars in the Large Magellanic Cloud has been observed in the red part of the spectrum with the 2dF facility on the AAT. Of these, 156 have been identified as J-type (i.e. 13C-rich) carbon stars using a technique which provides a clear distinction between J stars and the normal N-type carbon stars that comprise the bulk of the sample, and yields few borderline cases. A simple 2-D classification of the spectra, based on their spectral slopes in different wavelength regions, has been constructed and found to be related to the more conventional c- and j-indices, modified to suit the spectral regions observed. Most of the J stars form a photometric sequence in the K - (J-K) colour magnitude diagram, parallel to and 0.6 mag fainter than the N star sequence. A subset of the J stars (about 13 per cent) are brighter than this J star sequence; most of these are spectroscopically different from the other J stars. The bright J stars have stronger CN bands than the other J stars and are found strongly concentrated in the central regions of the LMC. Most of the rather few stars in common with Hartwick and Cowley's sample of suspected CH stars are J stars. Overall, the proportion of carbon stars identified as J stars is somewhat lower than has been found in the Galaxy. The Na D lines are weaker in the LMC J stars than in either the Galactic J stars or the LMC N stars, and do not seem to depend on temperature.Comment: 19 pages, 21 figures, Latex; in press, MNRA

Scanning Tunneling Spectroscopy in MgB2

We present scanning tunneling microscopy measurements of the surface of superconducting MgB2 with a critical temperature of 39K. In zero magnetic field the conductance spectra can be analyzed in terms of the standard BCS theory with a smearing parameter Gamma. The value of the superconducting gap is 5.2 meV at 4.2 K, with no experimentally significant variation across the surface of the sample. The temperature dependence of the gap follows the BCS form, fully consistent with phonon-mediated superconductivity in this novel superconductor. The application of a magnetic field induces strong pair-breaking as seen in the conductance spectra in fields up to 6 T.Comment: 4 pages, 4 figure