Quench characteristics of a stabilizer-free 2G HTS conductor

The prospect of medium/high field superconducting magnets using second generation (2G) HTS tapes is approaching reality with continued enhancement in the performance of these conductors. While the cryogenic stability and quench propagation are fundamental issues for the design and safe operation of superconducting magnets, there is insufficient understanding and experimental data for 2G HTS conductors, in particular for the high field scenario at low temperature (<77 K) where the current sharing regime is much larger than in low temperature superconductors. The present work includes a systematic characterization of the relevant thermal-electrical properties used for both qualitative discussion and numerical analysis. Direct measurements of one dimensional adiabatic quench initiation and propagation of a stabilizer-free 2G conductor have been carried out with spatial-temporal recording of temperature and voltage following the deposition of varying local heat pulses to the conductor at different temperatures between 30 K and 77 K carrying different transport currents. The minimum quench energy, and the heat generation in the minimum propagation zone (MPZ) have been obtained as a function of temperature and transport current. The results show quench features unique to HTS such as an increasing MPZ with transport current and higher quench energies at lower temperatures. The experimental results are discussed in the context of current sharing over a large temperature range

The Vincentian Archives of the Eastern Province, Saint John’s University.

This inventory of the Eastern Province’s Vincentian archives at St. John’s University includes: original letters from Vincent de Paul as well as biographies of him; biographies of Louise de Marillac and of the Double Family’s saints, blessed, and venerable; biographies of Vincentians and Daughters of Charity; material on the Congregation’s history, particularly in the United States; official documents, such as the Congregation’s rules and constitutions; circulars of the superiors general; personnel records and catalogues; publications like Annales de la Mission; unpublished material, including records of general assemblies, and provincial assemblies of the Eastern Province; and material about the Eastern Province’s missions and houses

Status of the Dorcas gazelle (Gazella dorcas) in the area south of Green Mountain, Libya in 2007: challenges and opportunities for the future

Threats to Dorcas gazelle were examined and the rate of decrease in population was estimated in the area south of the Green Mountain in North-East Libya. The results were collected from questionnaires and focal interviews. All previous studies had reported significant decreased in Dorcas gazelle population throughout Libya during the last years of the twentieth century. The results showed that Dorcas gazelle continues to exist but in very low numbers. The number of groups of gazelle has decreased and the estimated rate of decline has increased to between 60 and 90 % in 2007. The decline has been noticeable with typical herd sizes of approximately 50 – 100 gazelle being reported before 1970, 10 – 15 gazelle seen in the 1970s, 5 – 10 gazelle in the 1980s and from the 1990s onwards, group sizes of only 3 or fewer gazelles. Shared use of habitat with domestic sheep and predators does not appear to be detrimental to Dorcas gazelle, but the main threat for this animal is humans, who lack awareness of its natural value. Some respondents believed that Dorcas gazelle had left their habitat and migrated to other safe areas, but this study showed that the number of Dorcas gazelle was decreasing rapidly, mainly because of overhunting. Further research is needed into the current distribution and numbers of surviving Dorcas gazelle. Aerial and ground surveys of areas of potential habitat should be carried out to establish the current status and distribution. There is an urgent need for the implementation of management programme to conserve the gazelle involving the participation of local people

Feeding Behavior of Yorkshire Pigs Selected for Residual Feed Intake

Feeding behavior traits were evaluated in Yorkshire gilts from the fourth generation of the ISU residual feed intake (RFI) selection experiment. Gilts were fed using FIRE feeders. Compared to the randomly selected control line, pigs from the line selected for lower RFI, had lower residual feed intake, ate less per day, spent less time eating per day, and ate faster per visit, regardless of whether analysis was over the whole test period, the first half of test period, or the second half of test period. In conclusion, selection for lower RFI has significantly changed feeding behavior, which could be part of the reason why they are more efficient

Low Energy Excitations in Spin Glasses from Exact Ground States

We investigate the nature of the low-energy, large-scale excitations in the three-dimensional Edwards-Anderson Ising spin glass with Gaussian couplings and free boundary conditions, by studying the response of the ground state to a coupling-dependent perturbation introduced previously. The ground states are determined exactly for system sizes up to 12^3 spins using a branch and cut algorithm. The data are consistent with a picture where the surface of the excitations is not space-filling, such as the droplet or the ``TNT'' picture, with only minimal corrections to scaling. When allowing for very large corrections to scaling, the data are also consistent with a picture with space-filling surfaces, such as replica symmetry breaking. The energy of the excitations scales with their size with a small exponent \theta', which is compatible with zero if we allow moderate corrections to scaling. We compare the results with data for periodic boundary conditions obtained with a genetic algorithm, and discuss the effects of different boundary conditions on corrections to scaling. Finally, we analyze the performance of our branch and cut algorithm, finding that it is correlated with the existence of large-scale,low-energy excitations.Comment: 18 Revtex pages, 16 eps figures. Text significantly expanded with more discussion of the numerical data. Fig.11 adde

Plasticity and learning in a network of coupled phase oscillators

A generalized Kuramoto model of coupled phase oscillators with slowly varying coupling matrix is studied. The dynamics of the coupling coefficients is driven by the phase difference of pairs of oscillators in such a way that the coupling strengthens for synchronized oscillators and weakens for non-synchronized pairs. The system possesses a family of stable solutions corresponding to synchronized clusters of different sizes. A particular cluster can be formed by applying external driving at a given frequency to a group of oscillators. Once established, the synchronized state is robust against noise and small variations in natural frequencies. The phase differences between oscillators within the synchronized cluster can be used for information storage and retrieval.Comment: 10 page

Quasi-1D dynamics and nematic phases in the 2D Emery model

We consider the Emery model of a Cu-O plane of the high temperature superconductors. We show that in a strong-coupling limit, with strong Coulomb repulsions between electrons on nearest-neighbor O sites, the electron-dynamics is strictly one dimensional, and consequently a number of asymptotically exact results can be obtained concerning the electronic structure. In particular, we show that a nematic phase, which spontaneously breaks the point- group symmetry of the square lattice, is stable at low enough temperatures and strong enough coupling.Comment: 8 pages, 5 eps figures; revised manuscript with more detailed discussions; two new figures and three edited figuresedited figures; 14 references; new appendix with a detailed proof of the one-dimensional dynamics of the system in the strong coupling limi

Rms-flux relation in the optical fast variability data of BL Lacertae object S5 0716+714

The possibility that BL Lac S5 0716+714 exhibits a linear root mean square (rms)-flux relation in its IntraDay Variability (IDV) is analysed. The results may be used as an argument in the existing debate regarding the source of optical IDV in Active Galactic Nuclei. 63 time series in different optical bands were used. A linear rms-flux relation at a confidence level higher than 65% was recovered for less than 8% of the cases. We were able to check if the magnitude is log-normally distributed for eight timeseries and found, with a confidence > 95%, that this is not the case.Comment: Accepted by Astrophysics and Space Scienc