Rotating Machine Technologies for Integration of Pulsed and High Power Loads in Naval Electric Power Systems

Advanced electric sensors and weapons are placing increasing demands on the electric power distribution systems of future naval vessels and energy storage is viewed as a critical technology for effective integration of IPS architectures in these platforms. This paper shows that kinetic energy storage, i.e. stored in the angular momentum of a rotating mass, can be applied in differing topologies to address a range of ship power system applications. Rotating machine technologies are presented for UPS and load leveling applications as well as for high cycle rate pulsed power applications.Center for Electromechanic

Effect of Pt doping on the critical temperature and upper critical field in YNi2-xPtxB2C (x=0-0.2)

We investigate the evolution of superconducting properties by doping non-magnetic impurity in single crystals of YNi2-xPtxB2C (x=0-0.2). With increasing Pt doping the critical temperature (Tc) monotonically decreases from 15.85K and saturates to a value ~13K for x>0.14. However, unlike conventional s-wave superconductors, the upper critical field (HC2) along both crystallographic directions a and c decreases with increasing Pt doping. Specific heat measurements show that the density of states (N(EF)) at the Fermi level (EF) and the Debye temperatures (Theta_D) in this series remains constant within the error bars of our measurement. We explain our results based on the increase in intraband scattering in the multiband superconductor YNi2B2C.Comment: ps file with figure

Disease Surveillance Networks Initiative Asia: Final Evaluation

The DSN Initiative was launched in 2007 under the new strategy of the Rockefeller Foundation. The initiative intends:[1] To improve human resources for disease surveillance in developing countries, thus bolstering national capacity to monitor, report, and respond to outbreaks;[2] To support regional networks to promote collaboration in disease surveillance and response across countries; and[3] To build bridges between regional and global monitoring effortsThe purpose of the DSN evaluation in the Mekong region was twofold:[1]To inform the work and strategy of the Foundation, its grantees, and the broader field of disease surveillance, based on the experience of DSN investments in the Mekong region. More specifically, the evaluation will inform future directions and strategies for current areas of DSN Initiative work, particularly in Asia, and will highlight potential new areas of work and strategy; and[2] To provide accountability to the Rockefeller Foundation's board, staff, and stakeholders for the DSN funds spent in the Mekong region

Temperature dependence of transport spin polarization in NdNi5 measured using Point Contact Andreev reflection

We report a study in which Point contact Andreev reflection (PCAR) spectroscopy using superconducting Nb tip has been carried out on NdNi5, a ferromagnet with a Curie temperature of TC~7.7K. The measurements were carried out over a temperature range of 2-9K which spans across the ferromagnetic transition temperature. From an analysis of the spectra, we show that (i) the temperature dependence of the extracted value of transport spin polarization closely follows the temperature dependence of the spontaneous magnetization; (ii) the superconducting quasiparticle lifetime shows a large decrease close to the Curie temperature of the ferromagnet. We attribute the latter to the presence of strong ferromagnetic spin fluctuations in the ferromagnet close to the ferromagnetic transition temperature.Comment: pdf file including figures-Typographical error and errors in references correcte

Non-linear IVIV characteristics in two-dimensional superconductors: Berezinskii-Kosterlitz-Thouless physics vs inhomogeneity

One of the hallmarks of the Berezinskii-Kosterlitz-Thouless (BKT) transition in two-dimensional (2D) superconductors is the universal jump of the superfluid density, that can be indirectly probed via the non-linear exponent of the current-voltage $IV$ characteristics. Here, we compare the experimental measurements of $IV$ characteristics in two cases, namely NbN thin films and SrTiO$_3$-based interfaces. While the former display a paradigmatic example of BKT-like non-linear effects, the latter do not seem to justify a BKT analysis. Rather, the observed $IV$ characteristics can be well reproduced theoretically by modelling the effect of mesoscopic inhomogeneity of the superconducting state. Our results offer an alternative perspective on the spontaneous fragmentation of the superconducting background in confined 2D systems.Comment: Final version, as publishe

Vortex matching effect in engineered thin films of NbN

We report robust vortex matching effects in antidot arrays fabricated on thin films of NbN. The near absence of hysteresis between field sweep directions indicates a negligible residual pinning in the host thin film. Owing to the very small coherence length of NbN thin films ($\xi < 5 nm$), the observations suggests the possibility of probing physics of vortices at true nanometer length scales in suitably fabricated structures.Comment: Submitted to Appl. Phys. Let

Surgical Stabilization of Femur Fractures in Post-Traumatic Hypoxemic Patients: When and Why?

Background: Post-traumatic hypoxemia can deteriorate during operative manipulations. Objectives: In the present study, criteria-based approach was applied to determine optimum conditions for femur surgery. The aim of this study was to optimize perioperative management of post-traumatic hypoxemia. Patients and Methods: In this prospective observational study, post-traumatic adults with PaO2 200 mmHg (FiO2 < 0.5, PEEP < 8 cm H2O). Results: A total of 31 adults (26 males and 5 females) with LIS of 0.1 to 2.5 (26 patients) and > 2.5 (five patients) at admission were recruited. Sixteen patients were admitted within 24 hours and 15 between 24 and 90 hours after injury. Thirteen patients were operated within 24 hours. Post-operative LIS was improved. No adverse sequels or mortality were seen. Conclusions: Appropriate surgical stabilization can be safely performed during established post-traumatic hypoxemia using a multidisciplinary approach, continuous monitoring, and serial investigations to diagnose fulminant pathology and associated injuries