Effect of the NACA Injection Impeller on the Mixture Distribution of a Double-Row Radial Aircraft Engine

The NACA injection impeller was developed to improve the mixture distribution of aircraft engines by discharging the fuel from a centrifugal supercharger impeller, thus promoting a thorough mixing of fuel and charge air. Tests with a double-row radial aircraft engine indicated that for the normal range of engine power the NACA injection impeller provided marked improvement in mixture distribution over the standard spray-bar injection system used in the same engine. The mixture distribution at cruising conditions was excellent; at 1200, 15OO, and 1700 brake horsepower, the differences between the fuel-air ratios of the richest and the leanest cylinders were reduced to approximately one-third their former values. The maximum cylinder temperatures were reduced about 30 [degrees] F and the temperature distribution was improved by approximately the degree expected from the improvement in mixture distribution. Because the mixture distribution of the engine tested improves slightly at engine powers exceeding 1500 brake horsepower and because the effectiveness of the particular impeller diminished slightly at high rates of fuel flow, the improvement in mixture distribution at rated power and rich mixtures was less than that for other conditions. The difference between the fuel-air ratios of the richest and the leanest cylinders of the engine using the standard spray bar was so great that the fuel-air ratios of several cylinders were well below the chemically correct mixture, whereas other cylinders were operating at rich mixtures. Consequently, enrichment to improve engine cooling actually increascd some of the critical temperatures. The uniform mixture distribution providod by the injection impeller restored the normal response of cylinder temperatures to mixture enrichnent

Statistics on clouds and their relation to thermodynamic conditions at Ny-Ålesund

The French–German Arctic research base AWIPEV (the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research – AWI – and the French Polar Institute Paul Emile Victor – PEV) at Ny-Ålesund, Svalbard, is a unique station for monitoring cloud-related processes in the Arctic. For the first time, data from a set of ground-based instruments at the AWIPEV observatory are analyzed to characterize the vertical structure of clouds. For this study, a 14-month dataset from Cloudnet combining observations from a ceilometer, a 94 GHz cloud radar, and a microwave radiometer is used. A total cloud occurrence of ∼81 %, with 44.8 % multilayer and 36 % single-layer clouds, was found. Among single-layer clouds the occurrence of liquid, ice, and mixed-phase clouds was 6.4 %, 9 %, and 20.6 %, respectively. It was found that more than 90 % of single-layer liquid and mixed-phase clouds have liquid water path (LWP) values lower than 100 and 200 g m−2, respectively. Mean values of ice water path (IWP) for ice and mixed-phase clouds were found to be 273 and 164 g m−2, respectively. The different types of single-layer clouds are also related to in-cloud temperature and the relative humidity under which they occur. Statistics based on observations are compared to ICOsahedral Non-hydrostatic (ICON) model output. Distinct differences in liquid-phase occurrence in observations and the model at different environmental temperatures lead to higher occurrence of pure ice clouds. A lower occurrence of mixed-phase clouds in the model at temperatures between −20 and −5 ∘C becomes evident. The analyzed dataset is useful for satellite validation and model evaluation

Cygnus X-2: the Descendant of an Intermediate-Mass X-Ray Binary

The X-ray binary Cygnus X-2 (Cyg X-2) has recently been shown to contain a secondary that is much more luminous and hotter than is appropriate for a low-mass subgiant. We present detailed binary-evolution calculations which demonstrate that the present evolutionary state of Cyg X-2 can be understood if the secondary had an initial mass of around 3.5 M_sun and started to transfer mass near the end of its main-sequence phase (or, somewhat less likely, just after leaving the main sequence). Most of the mass of the secondary must have been ejected from the system during an earlier rapid mass-transfer phase. In the present phase, the secondary has a mass of around 0.5 M_sun with a non-degenerate helium core. It is burning hydrogen in a shell, and mass transfer is driven by the advancement of the burning shell. Cyg X-2 therefore is related to a previously little studied class of intermediate-mass X-ray binaries (IMXBs). We suggest that perhaps a significant fraction of X-ray binaries presently classified as low-mass X-ray binaries may be descendants of IMXBs and discuss some of the implications

Constraints on Light Pseudoscalars Implied by Tests of the Gravitational Inverse-Square Law

The exchange of light pseudoscalars between fermions leads to a spin-independent potential in order g^4, where g is the Yukawa pseudoscalar-fermion coupling constant. This potential gives rise to detectable violations of both the weak equivalence principle (WEP) and the gravitational inverse-square law (ISL), even if g is quite small. We show that when previously derived WEP constraints are combined with those arisingfrom ISL tests, a direct experimental limit on the Yukawa coupling of light pseudoscalars to neutrons can be inferred for the first time (g_n^2/4pi < 1.6 \times 10^-7), along with a new (and significantly improved) limit on the coupling of light pseudoscalars to protons.Comment: 12 pages, Revtex, with 1 Postscript figure (submitted to Physical Review Letters

Magneto-structural properties of the layered quasi-2D triangular-lattice antiferromagnets Cs2_2CuCl4−x_{4-x}Brx_x for x{x} = 0,1,2 and 4

We present a study of the magnetic susceptibility $\chi_{mol}$ under variable hydrostatic pressure on single crystals of Cs$_2$CuCl$_{4-x}$Br$_x$. This includes the border compounds \textit{x} = 0 and 4, known as good realizations of the distorted triangular-lattice spin-1/2 Heisenberg antiferromagnet, as well as the isostructural stoichiometric systems Cs$_2$CuCl$_{3}$Br$_1$ and Cs$_2$CuCl$_{2}$Br$_2$. For the determination of the exchange coupling constants $J$ and $J^{\prime}$, $\chi_{mol}$ data were fitted by a $J-J^{\prime}$ model \cite{Schmidt2015}. Its application, validated for the border compounds, yields a degree of frustration $J^{\prime}$/$J$ = 0.47 for Cs$_2$CuCl$_3$Br$_1$ and $J^{\prime}$/$J$ $\simeq$ 0.63 - 0.78 for Cs$_2$CuCl$_2$Br$_2$, making these systems particular interesting representatives of this family. From the evolution of the magnetic susceptibility under pressure up to about 0.4\,GPa, the maximum pressure applied, two observations were made for all the compounds investigated here. First, we find that the overall energy scale, given by $J_c = (J^2$ + $J^{\prime 2}$)$^{1/2}$, increases under pressure, whereas the ratio $J^{\prime}$/$J$ remains unchanged in this pressure range. These experimental observations are in accordance with the results of DFT calculations performed for these materials. Secondly, for the magnetoelastic coupling constants, extraordinarily small values are obtained. We assign these observations to a structural peculiarity of this class of materials

Sexual violence in post-conflict Liberia: survivors and their care.

Using routine data from three clinics offering care to survivors of sexual violence (SV) in Monrovia, Liberia, we describe the characteristics of SV survivors and the pattern of SV and discuss how the current approach could be better adapted to meet survivors' needs. There were 1500 survivors seeking SV care between January 2008 and December 2009. Most survivors were women (98%) and median age was 13 years (Interquartile range: 9-17 years). Sexual aggression occurred during day-to-day activities in 822 (55%) cases and in the survivor's home in 552 (37%) cases. The perpetrator was a known civilian in 1037 (69%) SV events. Only 619 (41%) survivors sought care within 72 h. The current approach could be improved by: effectively addressing the psychosocial needs of child survivors, reaching male survivors, targeting the perpetrators in awareness and advocacy campaigns and reducing delays in seeking care

Current state of neuroprotective therapy using antibiotics in human traumatic brain injury and animal models

TBI is a leading cause of death and disability in young people and older adults worldwide. There is no gold standard treatment for TBI besides surgical interventions and symptomatic relief. Post-injury infections, such as lower respiratory tract and surgical site infections or meningitis are frequent complications following TBI. Whether the use of preventive and/or symptomatic antibiotic therapy improves patient mortality and outcome is an ongoing matter of debate. In contrast, results from animal models of TBI suggest translational perspectives and support the hypothesis that antibiotics, independent of their anti-microbial activity, alleviate secondary injury and improve neurological outcomes. These beneficial effects were largely attributed to the inhibition of neuroinflammation and neuronal cell death. In this review, we briefly outline current treatment options, including antibiotic therapy, for patients with TBI. We then summarize the therapeutic effects of the most commonly tested antibiotics in TBI animal models, highlight studies identifying molecular targets of antibiotics, and discuss similarities and differences in their mechanistic modes of action

The Turn-On of Mass Transfer in AM CVn Binaries: Implications for RX J0806+1527 and RX J1914+2456

We report on evolutionary calculations of the onset of mass transfer in AM CVn binaries, treating the donor's evolution in detail. We show that during the early contact phase, while the mass transfer rate, \Mdot, is increasing, gravity wave (GW) emission continues to drive the binary to shorter orbital period, \Porb. We argue that the phase where \Mdot > 0 and \nudot > 0 (\nu = 1/\Porb) can last between $10^3$ and $10^6$ yrs, significantly longer than previously estimated. These results are applied to RX J0806+1527 (\Porb = 321 s) and RX J914+2456 (\Porb=569 s), both of which have measured \nudot > 0. \emph{Thus, a \nudot > 0 does not select between the unipolar inductor and accretion driven models proposed as the source of X-rays in these systems}. For the accretion model, we predict for RX J0806 that \ddot{\nu} \approx \ee{1.0-1.5}{-28} Hz s$^{-2}$ and argue that timing observations can probe $\ddot{\nu}$ at this level with a total $\approx 20$ yr baseline. We also place constraints on each system's initial parameters given current observational data.Comment: 5 pages, 3 figures, accepted to ApJ