First dielectronic recombination measurements with H-like uranium

In this report we show first results on dielectronic recombination (DR) measurements with H-like uranium U91+. The experiments were conducted at the heavy ion storage ring ESR of GSI. The electron cooler of the ESR was used as a target for free electrons. Stochastic pre-cooling of the stored ion beam was employed in order to accomplish high-energy resolution at the necessary high electron-ion collision energies of more than 64 keV. For the DR of U91+ this novel technique enabled us to measure for the first time the KLL-DR process and even to resolve the individual j-j' fine structure components of the KLjLj' resonances. The experimental data are compared with fully relativistic Multi-Configuration Dirac-Fock (DR-MCDF) calculations. (c) 2006 Elsevier Ltd. All rights reserved.

DES14X3taz: A Type I Superluminous Supernova Showing a Luminous, Rapidly Cooling Initial Pre-peak Bump

We present DES14X3taz, a new hydrogen-poor superluminous supernova (SLSN-I) discovered by the Dark Energy Survey (DES) supernova program, with additional photometric data provided by the Survey Using DECam for Superluminous Supernovae. Spectra obtained using Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy on the Gran Telescopio CANARIAS show DES14X3taz is an SLSN-I at z = 0.608. Multi-color photometry reveals a double-peaked light curve: a blue and relatively bright initial peak that fades rapidly prior to the slower rise of the main light curve. Our multi-color photometry allows us, for the first time, to show that the initial peak cools from 22,000 to 8000 K over 15 rest-frame days, and is faster and brighter than any published core-collapse supernova, reaching 30% of the bolometric luminosity of the main peak. No physical 56Ni-powered model can fit this initial peak. We show that a shock-cooling model followed by a magnetar driving the second phase of the light curve can adequately explain the entire light curve of DES14X3taz. Models involving the shock-cooling of extended circumstellar material at a distance of 400  are preferred over the cooling of shock-heated surface layers of a stellar envelope. We compare DES14X3taz to the few double-peaked SLSN-I events in the literature. Although the rise times and characteristics of these initial peaks differ, there exists the tantalizing possibility that they can be explained by one physical interpretation.

Experimental Investigation into the Free-Air Cooling of Air-Cooled Cylinders

This paper describes an experimental investigation into the surface heat transfer coefficient of finned metal cylinders in a free air stream. Eight cast aluminium alloy cylinders were tested with four different fin pitches and five different fin lengths. The cylinders and their fins were designed to be representative of those found on a motorcycle engine. Each electrically heated cylinder was mounted in a wind tunnel and subjected to a range of air speeds between 2 and 20 m/s. The surface heat transfer coefficient, h, was found primarily to be a function of the air speed and the fin separation, with fin length having a lesser effect. The coefficient increases with airspeed and as the fins are separated or shortened. It was also noted that a limiting value of coefficient exists, influenced only by airspeed. Above the limiting value the surface heat transfer could not be increased by further separation of the fins or reduction in their length.

Recombinant alpha 2(IV)NC1 domain of type IV collagen is an effective regulator of retinal capillary endothelial cell proliferation and inhibits pre-retinal neovascularisation

Background A recombinant form of the alpha 2(IV)NC1 domain of type IV collagen has been shown to have potent anti-angiogenic activity although this peptide has not been studied in the context of proliferative retinopathies. In the current investigation we examined the potential for alpha 2(IV) NC1 to regulate retinal microvascular endothelial cell function using a range of in vitro and in vivo assay systems.

Cryopreservation of human semen and prepared sperm: effects on motility parameters and DNA integrity

Objective: To investigate effects of cryopreservation on sperm motility and DNA integrity. Design: Pre-cryopreservation and post-cryopreservation analysis of motility and DNA integrity of semen and prepared sperm samples. Setting: A hospital andrology laboratory. Patient(s): Forty men attending the Regional Fertility Centre, Belfast, Northern Ireland. Intervention(s): Each sample was divided, and an aliquot was frozen unprepared. Remaining aliquots were prepared by Percoll density centrifugation (95.0:47.5) or direct swim-up procedure and divided into aliquots to allow direct comparison of fresh and frozen semen and prepared sperm (frozen with or without the addition of seminal plasma) from the same ejaculate. Samples were frozen by static-phase vapor cooling and being plunged into liquid nitrogen. Thawing was carried out at room temperature. Main Outcome Measure(s): Sperm DNA integrity was determined using a modified alkaline single cell gel electrophoresis (comet) assay, and motility was determined using computer-assisted semen analysis. Result(s): Sperm frozen unprepared in seminal fluid appeared more resistant to freezing damage than frozen prepared sperm. Further improvements can be achieved by selecting out the subpopulation of sperm with best motility and DNA integrity and freezing these sperm in seminal plasma, making this the optimal procedure. Conclusion(s): Freezing sperm in seminal plasma improves postthaw motility and DNA integrity.

EMI Suppression in an Aircraft Cooling Vent

Digital avionics systems are increasingly under threat from external electromagnetic interference (EMI). The same avionics systems require a thermal cooling mechanism and one method of providing this is to mount an air vent on the body of the aircraft. For the first time, a nacelle-mounted air vent that may expose the flight critical full authority digital engine controller (FADEC) to high intensity radiated fields (HIRF) is examined. The reflection/transmission characteristics of the vent are reported and the current shielding method employed is shown to provide a low shielding level (5 dB at 18 GHz). A new design has been proposed, providing over 100 dB of attenuation at 18 GHz. To the authors' knowledge this is the first time this shielding method has been applied to aircraft air vents.