Exhaust-nozzle characterisitcs for a twin-jet variable-wing-sweep fighter airplane model at Mach numbers to 2.2

A wind-tunnel investigation has been conducted to determine the exhaust-nozzle aerodynamic and propulsive characteristics for a twin-jet variable-wing-sweep fighter airplane model. The powered model was tested in the Langley 16-foot transonic tunnel and in the Langley 4-foot supersonic pressure tunnel at Mach numbers to 2.2 and at angles of attack from about minus 2 to 6 deg. Compressed air was used to simulate the nozzle exhaust flow at values of jet total-pressure ratio from approximately 1 (jet off) to about 21. Effects of configuration variables such as speed-brake deflection, store installation, and boundary-layer thickness on the the nozzle characteristics were also investigated

Effects of an in-flight thrust reverser on the stability and control characteristics of a single-engine fighter airplane model

The changes in thrust minus drag performance as well as longitudinal and directional stability and control characteristics of a single-engine jet aircraft attributable to an in-flight thrust reverser of the blocker-deflector door type were investigated in a 16-foot transonic wind tunnel. The longitudinal and directional stability data are presented. Test conditions simulated landing approach conditions as well as high speed maneuvering such as may be required for combat or steep descent from high altitude

The development of direct payments in the UK: implications for social justice

Direct payments have been heralded by the disability movement as an important means to achieving independent living and hence greater social justice for disabled people through enhanced recognition as well as financial redistribution. Drawing on data from the ESRC funded project Disabled People and Direct Payments: A UK Comparative Perspective, this paper presents an analysis of policy and official statistics on use of direct payments across the UK. It is argued that the potential of direct payments has only partly been realised as a result of very low and uneven uptake within and between different parts of the UK. This is accounted for in part by resistance from some Labour-controlled local authorities, which regard direct payments as a threat to public sector jobs. In addition, access to direct payments has been uneven across impairment groups. However, from a very low base there has been a rapid expansion in the use of direct payments over the past three years. The extent to which direct payments are able to facilitate the ultimate goal of independent living for disabled people requires careful monitoring

Effects of nozzle interfairing modifications on longitudinal aerodynamic characteristics of a twin jet, variable wing sweep fighter model

A wind-tunnel investigation has been made to determine the effects of nozzle interfairing modifications on the longitudinal aerodynamic characteristics of a twin-jet, variable-wing-sweep fighter model. The model was tested in the Langley 16-foot transonic tunnel at Mach numbers of 0.6 to 1.3 and angles of attack from about minus 2 deg to 6 deg and in the Langley 4-foot supersonic presure tunnel at a Mach number of 2.2 and an angle of attack of 0 deg. Compressed air was used to simulate nozzle exhaust flow at jet total-pressure ratios from 1 (jet off) to about 21. The results of this investigation show that the aircraft drag can be significantly reduced by replacing the basic interfairing with a modified interfairing

Trends in Frequency of Sexual Activity and Number of Sexual Partners Among Adults Aged 18 to 44 Years in the US, 2000-2018

Importance: Sexual relationships are important for well-being and health. Recent trends in sexual activity among US adults are unknown. Objectives: To examine trends in reported frequency of sexual activity and number of sexual partners by sex and age and the association between measures of sexual activity and sociodemographic variables. Design, Setting, and Participants: In this survey study, repeat, cross-sectional analyses of participants aged 18 to 44 years from 10 rounds of the General Social Survey (2000-2018), a US nationally representative survey, were performed for men and women separately. Main Outcomes and Measures: Sexual frequency in the past year (sexual inactivity, once or twice per year, 1-3 times per month, or weekly or more) and number of sexual partners in the past year (0, 1, 2, or ≥3 partners). The association between measures of sexual activity and sociodemographic variables were assessed using logistic regression. Results: The study population included 4291 men and 5213 women in the analysis of sexual frequency and 4372 men and 5377 women in the analysis of number of sexual partners (mean [SD] age, 31.4 [7.6] years; survey response rate, 59.5%-71.4%). Between 2000-2002 and 2016-2018, the proportion of 18- to 24-year-old individuals who reported having had no sexual activity in the past year increased among men (18.9% vs 30.9%; age-adjusted odds ratio [aOR] for trend across survey periods, 1.20; 95% CI, 1.04-1.39) but not among women (15.1% vs 19.1%; aOR for trend, 1.03; 95% CI, 0.89-1.18). Smaller absolute increases in sexual inactivity were observed among those aged 25 to 34 years for both men (7.0% vs 14.1%; aOR for trend, 1.23; 95% CI, 1.07-1.42) and women (7.0% vs 12.6%; aOR for trend, 1.17; 95% CI, 1.01-1.35) but not among those aged 35 to 44 years. The increase in sexual inactivity coincided with decreases in the proportion reporting weekly or more sexual frequency (men aged 18-24 years: 51.8% vs. 37.4%; aOR for trend, 0.88 [95% CI, 0.79-0.99]; men aged 25-34 years: 65.3% vs 50.3%; aOR for trend, 0.87 [95% CI, 0.81-0.94]; women aged 25-34 years: 66.4% vs. 54.2%; aOR for trend, 0.90 [95% CI, 0.84-0.96]) or 1 sexual partner (men aged 18-24 years: 44.2% vs. 30.0%; aOR for trend, 0.88 [95% CI, 0.80-0.98]; women aged 25-34 years: 79.6% vs 72.7%; aOR for trend, 0.91 [95% CI, 0.84-0.99]) and occurred mainly among unmarried men (unmarried men aged 18-44 years: 16.2% vs 24.4%; aOR for trend, 1.14 [95% CI, 1.04-1.25]). Among married men and women, weekly or more sexual frequency decreased (men: 71.1 % vs 57.7%; aOR for trend, 0.86 [95% CI, 0.79-0.93]; women: 69.1% vs 60.9%; aOR for trend, 0.92 [95% CI, 0.86-0.99]). Men with lower income (aOR for men with an annual income of ≥$50 000 vs$0-$9999, 0.37 [95% CI, 0.15-0.90]) and with part-time (aOR vs full-time employment, 2.08; 95% CI, 1.48-2.93) and no employment (aOR vs full-time employment, 2.08; 95% CI, 1.48-2.93) were more likely to be sexually inactive, as were men (aOR vs full-time employment, 2.94; 95% CI, 2.06-4.21) and women (aOR vs full-time employment, 2.37; 95% CI, 1.68-3.35) who were students. Conclusions and Relevance: This survey study found that from 2000 to 2018, sexual inactivity increased among US men such that approximately 1 in 3 men aged 18 to 24 years reported no sexual activity in the past year. Sexual inactivity also increased among men and women aged 25 to 34 years. These findings may have implications for public health

Computations for the 16-foot transonic tunnel, NASA, Langley Research Center, revision 1

The equations used by the 16 foot transonic tunnel in the data reduction programs are presented in eight modules. Each module consists of equations necessary to achieve a specific purpose. These modules are categorized in the following groups: tunnel parameters; jet exhaust measurements; skin friction drag; balance loads and model attitudes calculations; internal drag (or exit-flow distributions); pressure coefficients and integrated forces; thrust removal options; and turboprop options. This document is a companion document to NASA TM-83186, A User's Guide to the Langley 16 Foot Transonic Tunnel, August 1981

Life History of the Marine Isopod Cyathura polita in the Saint John River Estuary, New Brunswick: a Species at the Northern Extent of its Range

The marine isopod, Cyathura polita, inhabits estuaries on the east coast of North America from the Gulf of Mexico to the Bay of Fundy, Canada. We studied C. polita in the Saint John estuary to test for potential differences in life history that might occur because of the northern location of the population. In the Saint John, based on our interpretation from a six-month sampling program (May-October), the population exhibits a three-year life cycle, one year longer than more southern populations, and stretching over four summers. Our study supported the occurrence of protogynic hermaphroditism. After two summers as juveniles, individuals matured as females during their third summer, then displayed sex reversal by becoming males that fall, and finally reproducing as males in their fourth summer of life before death. Mean length of C. polita from the Saint John was greater than individuals from more southern populations (females, 13.8 ± 2.14 mm; males, 16.3 ± 2.41 mm). Annual brood release occurred in late July-early August. Mean fecundity of females was 53.2 ± 18.9 embryos per brood, which was greater than found in southern populations. Cyathura polita is rare in Canada and is known only from the Saint John and along the northern shore of the Bay of Fundy to the border of the United States

Crystallization of Yamato 980459 at 0.5 GPA: Are Residual Liquids Like QUE 94201?

The Martian basaltic meteorites Y980459 and QUE94201 (henceforth referred to as Y98 and QUE respectively) are thought to represent magmatic liquid compositions, rather than being products of protracted crystallization and accumulation like the majority of other martian meteorites. Both meteorite compositions have been experimentally crystallized at 1 bar, and liquidus phases were found to match corresponding mineral core compositions in the meteorites, consistent with the notion that these meteorites represent bona fide melts. They also represent the most primitive and most evolved basaltic martian samples, respectively. Y98 has Mg# (molar Mg/Mg+Fe) approximates 65, and lacks plagioclase; whereas QUE has Mg# approximates 40, and lacks olivine. However they share important geochemical characteristics (e.g. superchondritic CaO/Al2O3, very high epsilon(sub Nd) and low Sr-87/Sr-87) that suggest they sample a similar highly depleted mantle reservoir. As such, they represent likely endmembers of martian magmatic liquid compositions, and it is natural to seek petrogenetic linkages between the two. We make no claim that the actual meteorites themselves share a genetic link (the respective ages rule that out); we are exploring only in general whether primitive martian liquids like Y98 could evolve to liquids resembling QUE. Both experimental and computational efforts have been made to determine if there is indeed such a link. Recent petrological models at 1 bar generated using MELTS suggest that a QUE-like melt can be derived from a parental melt with a Y98 composition. However, experimental studies at 1 bar have been less successful at replicating this progression. Previous experimental crystallization studies of Y98 by our group at 0.5 GPa have produced melt compositions approaching that of QUE, although these results were complicated by the presence of small, variable amounts of H2O in some of the runs owing to the use of talc/pyrex experimental assemblies. Therefore we have repeated the four experiments, augmented with additional runs, all using BaCO3 cell assemblies, which are devoid of water, and these new experiments supersede those reported earlier. Here we report results of experiments simulating equilibrium crystallization; fractional crystallization experiments are currently underway

Post-activation performance enhancement in sprinters: effects of hard versus sand surfaces

Abstract This study aimed to compare the post-activation performance enhancement induced by successive drop-jumps performed on hard and sand surfaces in sprint and jump performance of top-level sprinters. Athletes were tested on two occasions. On each visit they were allocated to one of the experimental protocols, which consisted of performing 2x5 drop-jumps from a box with the height of 60-cm on hard or sand surfaces in randomized order, seven days apart. Prior to and 7 and 15-min after executing drop-jumps, sprinters performed countermovement jumps and 60-m sprint tests. Differences between sprinting splits and surfaces were assessed using a two-way analysis of variance with repeated measures. No significant differences in jump height or sprint time were observed (p>0.05), regardless of the surface used (i.e., hard or sand) during the conditioning activity (effect sizes [95% confidence intervals] ranging from 0.01 [-0.84;0.84] to 0.44 [-0.42;1.27]). Performing drop-jumps on sand or hard surfaces immediately before maximum sprinting bouts does not provide any advantage or disadvantage to top-level sprinters. Sprint coaches may prescribe short-plyometric training activities on sand surfaces even close to competitions, bearing in mind that this strategy will not compromise sprint-specific performance