Research and development of open-cycle fuel cells Fourth quarterly progress report, period ending Aug. 15, 1965

Digital computer program for minimizing weight of fuel cell power systems - prelaunch startup and instrumentation - mathematical model of static moisture removal process - fuel cell mode

Simulation of charged particle trajectories in the neutron decay correlation experiment abBA

The proposed neutron decay correlation experiment, abBA, will directly detect the direction of emission of decay protons and electrons as well as providing spectroscopic information for both particles. In order to provide this information, the abBA experiment incorporates spatially varying electric and magnetic fields. We report on detailed simulations of the decay particle trajectories in order to assess the impact of various systematic effects on the experimental observables. These include among others; adiabaticity of particle orbits, tracking of orbits, reversal of low energy protons due to inhomogeneous electric field, and accuracy of proton time of flight measurements. Several simulation methods were used including commercial software (Simion), custom software, as well as analytical tools based on the use of adiabatic invariants. Our results indicate that the proposed field geometry of the abBA spectrometer will be substantially immune to most systematic effects and that transport calculations using adiabatic invariants agree well with solution of the full equations of motion

The Pulse Scale Conjecture and the Case of BATSE Trigger 2193

The pulses that compose gamma-ray bursts (GRBs) are hypothesized to have the same shape at all energies, differing only by scale factors in time and amplitude. This "Pulse Scale Conjecture" is confirmed here between energy channels of the dominant pulse in GRB 930214c (BATSE trigger 2193), the single most fluent single-pulsed GRB that occurred before May 1998. Furthermore, pulses are hypothesized to start at the same time independent of energy. This "Pulse Start Conjecture" is also confirmed in GRB 930214c. Analysis of GRB 930214c also shows that, in general, higher energy channels show shorter temporal scale factors. Over the energy range 100 KeV - 1 MeV, it is found that the temporal scale factors between a pulse measured at different energies are related to that energy by a power law, possibly indicating a simple relativistic mechanism is at work. To test robustness, the Pulse Start and Pulse Scale Conjectures were also tested on the four next most fluent single-pulse GRBs. Three of the four clearly passed, with a second smaller pulse possibly confounding the discrepant test. Models where the pulse rise and decay are created by different phenomena do not typically predict pulses that satisfy both the Pulse Start Conjecture and the Pulse Scale Conjecture, unless both processes are seen to undergo common time dilation.Comment: 19 pages, 9 figures, analysis revised and extended, accepted to Ap

Line shifts in the first overtone of DF broadened by HF

Line spectra shifts in HF and in first overtone band of DF induced by HF pressure

Ultracold neutron depolarization in magnetic bottles

We analyze the depolarization of ultracold neutrons confined in a magnetic field configuration similar to those used in existing or proposed magneto-gravitational storage experiments aiming at a precise measurement of the neutron lifetime. We use an extension of the semi-classical Majorana approach as well as an approximate quantum mechanical analysis, both pioneered by Walstrom et al. [Nucl. Instr. Meth. Phys. Res. A 599, 82 (2009)]. In contrast with this previous work we do not restrict the analysis to purely vertical modes of neutron motion. The lateral motion is shown to cause the predominant depolarization loss in a magnetic storage trap. The system studied also allowed us to estimate the depolarization loss suffered by ultracold neutrons totally reflected on a non-magnetic mirror immersed in a magnetic field. This problem is of preeminent importance in polarized neutron decay studies such as the measurement of the asymmetry parameter A using ultracold neutrons, and it may limit the efficiency of ultracold neutron polarizers based on passage through a high magnetic field.Comment: 18 pages, 6 figure

Placental-mediated increased cytokine response to lipopolysaccharides: a potential mechanism for enhanced inflammation susceptibility of the preterm fetus.

BackgroundCerebral palsy is a nonprogressive motor impairment syndrome that has no effective cure. The etiology of most cases of cerebral palsy remains unknown; however, recent epidemiologic data have demonstrated an association between fetal neurologic injury and infection/inflammation. Maternal infection/inflammation may be associated with the induction of placental cytokines that could result in increased fetal proinflammatory cytokine exposure, and development of neonatal neurologic injury. Therefore, we sought to explore the mechanism by which maternal infection may produce a placental inflammatory response. We specifically examined rat placental cytokine production and activation of the Toll-like receptor 4 (TLR4) pathway in response to lipopolysaccharide exposure at preterm and near-term gestational ages.MethodsPreterm (e16) or near-term (e20) placental explants from pregnant rats were treated with 0, 1, or 10 μg/mL lipopolysaccharide. Explant integrity was assessed by lactate dehydrogenase assay. Interleukin-6 and tumor necrosis alpha levels were determined using enzyme-linked immunosorbent assay kits. TLR4 and phosphorylated nuclear factor kappa light chain enhancer of activated B cells (NFκB) protein expression levels were determined by Western blot analysis.ResultsAt both e16 and e20, lactate dehydrogenase levels were unchanged by treatment with lipopolysaccharide. After exposure to lipopolysaccharide, the release of interleukin-6 and tumor necrosis alpha from e16 placental explants increased by 4-fold and 8-9-fold, respectively (P < 0.05 versus vehicle). Conversely, interleukin-6 release from e20 explants was not significantly different compared with vehicle, and tumor necrosis alpha release was only 2-fold higher (P < 0.05 versus vehicle) following exposure to lipopolysaccharide. Phosphorylated NFκB protein expression was significantly increased in the nuclear fraction from placental explants exposed to lipopolysaccharide at both e16 and e20, although TLR4 protein expression was unaffected.ConclusionLipopolysaccharide induces higher interleukin-6 and tumor necrosis alpha expression at e16 versus e20, suggesting that preterm placentas may have a greater placental cytokine response to lipopolysaccharide infection. Furthermore, increased phosphorylated NFκB indicates that placental cytokine induction may occur by activation of the TLR4 pathway