Aerodynamic performance of flared fan nozzles used as inlets

Tests were conducted in a low speed wind tunnel to determine the aerodynamic performance of several flared fan nozzles. Each of the flared nozzles was a downstream-facing inlet to a model fan that was used to simulate a variable pitch fan during reverse thrust operation. The total pressure recovery of each of the flared nozzles as well as that of an unflared nozzle and a serrated flare nozzle was obtained for comparison. The aerodynamic performance of a selected flared nozzle was considered in further detail. The nozzle surface pressures for a flared nozzle were also determined. Results indicated that the differences in aerodynamic performance among the nozzles were most apparent at the wind-tunnel-off condition. A nonzero free stream velocity significantly reduced the perforamnce of all the nozzles, and crosswind flow (free stream flow perpendicular to the model axis) further reduced the performance of the nozzles. The unflared nozzle and the serrated flare nozzle had reduced aerodynamic performance compared to a solid surface flared nozzle

Test results and facility description for a 40-kilowatt stirling engine

A 40 kilowatt Stirling engine, its test support facilities, and the experimental procedures used for these tests are described. Operating experience with the engine is discussed, and some initial test results are presente

Impact of titanium doping on Al self-diffusion in alumina

α-Al2O3 is an important refractory material which has numerous technical applications: as an in situ growing self-healing oxide scale, as a massive material and as reinforcement fibres in composites. For modelling diffusion controlled processes (creep, sintering, alpha-alumina scale growth on aluminium bearing Fe or Ni base alloys) it is necessary to study self-diffusion of the constituent elements

The spectral-type/luminosity and the spectral type/satellite-density relations in the 2dFGRS

We examine the relative fractions of passive (Type 1), quiet-SF (Type 2) and active-SF (Type 3+4) galaxies as a function of luminosity and number of neighbours in several volume limited samples selected from the 2dFGRS. Neighbours are counted within 1 $h_{75}^{-1}$ Mpc projected distance, and $\pm$ 1000 km s$^{-1}$ depth. We apply a maximum magnitude difference criterion and require neighbours to be fainter than the galaxy itself. We show that, whatever the environment, passive galaxies dominate in bright samples and active-SF galaxies in faint samples, whereas quiet-SF galaxies never dominate. We further show that in bright samples (M$_{B}$ -- 5 $\log$ $h_{75}$ $\leq$$- 19$) the fraction of passive galaxies grows steadily with fainter neighbour density, whereas in faint samples a threshold like dependence is observed. This suggests that the spectral-type / density ($\approx$ morphology / density) relation extends to intermediate dense environment, but only in the surrounding of luminous galaxies and that it reflects an enhancement of the number of satellites rather than stronger clustering among galaxies themselves. Our analysis indicates that, in general, luminosity is a good tracer of a galaxy halo mass and that it dominates over environment (satellite density) in setting the spectral type mix of a population. However, minority populations exist, such as luminous SF galaxies and faint passive galaxies, whose luminosity is an unfair tracer of halo mass.Comment: 8 pages, 5 figur

The Seyfert Population in the Local Universe

The magnitude-limited catalog of the Southern Sky Redshift Survey (SSRS2), is used to characterize the properties of galaxies hosting Active Galactic Nuclei. Using emission-line ratios, we identify a total of 162 (3%) Seyfert galaxies out of the parent sample with 5399 galaxies. The sample contains 121 Seyfert 2 galaxies and 41 Seyfert 1. The SSRS2 Seyfert galaxies are predominantly in spirals of types Sb and earlier, or in galaxies with perturbed appearance as the result of strong interactions or mergers. Seyfert galaxies in this sample are twice as common in barred hosts than the non-Seyferts. By assigning galaxies to groups using a percolation algorithm we find that the Seyfert galaxies in the SSRS2 are more likely to be found in binary systems, when compared to galaxies in the SSRS2 parent sample. However, there is no statistically significant difference between the Seyfert and SSRS2 parent sample when systems with more than 2 galaxies are considered. The analysis of the present sample suggests that there is a stronger correlation between the presence of the AGN phenomenon with internal properties of galaxies (morphology, presence of bar, luminosity) than with environmental effects (local galaxy density, group velocity dispersion, nearest neighbor distance).Comment: 35 pages, 13 figures, Accepted to be publised in Astronomical Journa

Brain Regional Differences in the Effect of Ethanol on GABA Release from Presynaptic Terminals

Whereas ethanol has behavioral actions consistent with increased GABAergic function, attempts to demonstrate a direct enhancement of GABA-gated currents by ethanol have produced mixed results. Recent work has suggested that a part of the GABAergic profile of ethanol may result from enhanced GABA release from presynaptic terminals. The present study examines the effect of ethanol on GABA release in several brain regions to assess the regional nature of ethanol-induced GABA release. Whole-cell voltage clamp recording of spontaneous inhibitory postsynaptic currents (sIPSCs) from mechanically dissociated neurons and miniature inhibitory postsynaptic currents (mIPSCs) and paired-pulse ratio (PPR) from a slice preparation were used to quantify GABA release. Ethanol produced a concentration-dependent increase in the frequency of sIPSCs recorded from mechanically dissociated cerebellar Purkinje neurons and mIPSCs from substantia nigra neurons without having an effect on sIPSCs recorded from lateral septal or cerebrocortical neurons. This regional difference in the effect of ethanol on GABA release was confirmed with PPR recording from brain slices. These data indicate that ethanol can act on presynaptic terminals to increase GABA release in some brain regions while having little or no effect on GABA release in others. This regional difference is consistent with earlier in vivo studies in which ethanol affected neural activity and sensitivity to GABA in some, but not all, brain sites

Small-scale systems of galaxies. II. Properties of the NGC 4756 group of galaxies

We present results from a study of the NGC 4756 group which is dominated by the elliptical galaxy NGC 5746. The characteristics of the group are investigated through (a) the detailed investigation of the morphological, photometric and spectroscopic properties of nine galaxies among the dominant members of the group (b) the determination of the photometric parameters of the faint galaxy population in an area of 34'x34' centered on NGC 4756 and (c) an analysis of the X-ray emission in the area based upon archival data. The 9 member galaxies are located in the core part of the NGC 4756 group (a strip diameter about 300 kpc in diameter which has a very loose configuration. The central part of the NGC 4756 group contains a significant fraction of early-type galaxies. Three new group members with previously unknown systemic velocities are identified, one of which is a dE. At about 7.5' SW of NGC 4756 a sub-structure of the group is detected, including IC 829, MCG -2-33-35, MCG -2-33-36 and MCG -2-33-38, which meets the Hickson criteria for being a compact group. Most of the galaxies in this sub-structure show interaction signatures. We do not detect apparent fine structure and signatures of recent interaction events in the early-type galaxy population, with the exception of a strong dust lane in the elliptical MCG -2-33-38. This galaxy displays however signatures of nuclear activity. Strong [O III], [N II] and [S II] line emission, combined with comparatively weak, but broad H alpha emission suggest an intermediate Seyfert type classification. Although the area is heavily contaminated by the background cluster Abell 1631, X-ray data suggest the presence of a hot intergalactic medium related to the group to the X-ray emission detected. The present results are discussed in the context of group evolution.Comment: 45 pages including 10 figures and 8 tables accepted for publication in A

An orifice shape-based reduced order model of patient-specific mitral valve regurgitation

Mitral valve regurgitation (MR) is one of the most prevalent valvular heart diseases. Its quantitative assessment is challenging but crucial for treatment decisions. Using computational fluid dynamics (CFD), we developed a reduced order model (ROM) describing the relationship between MR flow rates, transvalvular pressure differences, and the size and shape of the regurgitant valve orifice. Due to its low computational cost, this ROM could easily be implemented into clinical workflows to support the assessment of MR. We reconstructed mitral valves of 43 patients from 3D transesophageal echocardiographic images and estimated the 3D anatomic regurgitant orifice areas using a shrink-wrap algorithm. The orifice shapes were quantified with three dimensionless shape parameters. Steady-state CFD simulations in the reconstructed mitral valves were performed to analyse the relationship between the regurgitant orifice geometry and the regurgitant hemodynamics. Based on the results, three ROMs with increasing complexity were defined, all of which revealed very good agreement with CFD results with a mean bias below 3% for the MR flow rate. Classifying orifices into two shape groups and assigning group-specific flow coefficients in the ROM reduced the limit of agreement predicting regurgitant volumes from 9.0 ml to 5.7 ml at a mean regurgitant volume of 57 ml

Cocoa flavanol intake improves endothelial function and Framingham Risk Score in healthy men and women: a randomised, controlled, double-masked trial: the Flaviola Health Study

Cocoa flavanol (CF) intake improves endothelial function in patients with cardiovascular risk factors and disease. We investigated the effects of CF on surrogate markers of cardiovascular health in low risk, healthy, middle-aged individuals without history, signs or symptoms of CVD. In a 1-month, open-label, one-armed pilot study, bi-daily ingestion of 450 mg of CF led to a time-dependent increase in endothelial function (measured as flow-mediated vasodilation (FMD)) that plateaued after 2 weeks. Subsequently, in a randomised, controlled, double-masked, parallel-group dietary intervention trial (Clinicaltrials.gov: NCT01799005), 100 healthy, middle-aged (35–60 years) men and women consumed either the CF-containing drink (450 mg) or a nutrient-matched CF-free control bi-daily for 1 month. The primary end point was FMD. Secondary end points included plasma lipids and blood pressure, thus enabling the calculation of Framingham Risk Scores and pulse wave velocity. At 1 month, CF increased FMD over control by 1·2 % (95 % CI 1·0, 1·4 %). CF decreased systolic and diastolic blood pressure by 4·4 mmHg (95 % CI 7·9, 0·9 mmHg) and 3·9 mmHg (95 % CI 6·7, 0·9 mmHg), pulse wave velocity by 0·4 m/s (95 % CI 0·8, 0·04 m/s), total cholesterol by 0·20 mmol/l (95 % CI 0·39, 0·01 mmol/l) and LDL-cholesterol by 0·17 mmol/l (95 % CI 0·32, 0·02 mmol/l), whereas HDL-cholesterol increased by 0·10 mmol/l (95 % CI 0·04, 0·17 mmol/l). By applying the Framingham Risk Score, CF predicted a significant lowering of 10-year risk for CHD, myocardial infarction, CVD, death from CHD and CVD. In healthy individuals, regular CF intake improved accredited cardiovascular surrogates of cardiovascular risk, demonstrating that dietary flavanols have the potential to maintain cardiovascular health even in low-risk subjects