Water facilities in retrospect and prospect: An illuminating tool for vehicle design

Water facilities play a fundamental role in the design of air, ground, and marine vehicles by providing a qualitative, and sometimes quantitative, description of complex flow phenomena. Water tunnels, channels, and tow tanks used as flow-diagnostic tools have experienced a renaissance in recent years in response to the increased complexity of designs suitable for advanced technology vehicles. These vehicles are frequently characterized by large regions of steady and unsteady three-dimensional flow separation and ensuing vortical flows. The visualization and interpretation of the complicated fluid motions about isolated vehicle components and complete configurations in a time and cost effective manner in hydrodynamic test facilities is a key element in the development of flow control concepts, and, hence, improved vehicle designs. A historical perspective of the role of water facilities in the vehicle design process is presented. The application of water facilities to specific aerodynamic and hydrodynamic flow problems is discussed, and the strengths and limitations of these important experimental tools are emphasized

Tungsten nuclear rocket, phase II, part 1 Final report, Jan. 16 - Jun. 15, 1966

Critical experiments and nuclear analyses of tungsten water moderated nuclear rocket reacto

Tungsten nuclear rocket, phase I, part 1 Final report

Tungsten water moderated nuclear rocket reactor experiments and analyse

Properties of the Interstitial in the Diamond-Type Lattice

Linear combination of atomic orbital—molecular orbital cluster calculations using extended Hückel theory suggest that the interstitial carbon atom in diamond prefers an interstitialcy configuration. The predicted minimum-energy configuration changes with charge state, providing a possible example of the Bourgoin mechanism for athermal migration of the interstitial in the presence of ionizing radiation

Pole structure of the Hamiltonian ζ\zeta-function for a singular potential

We study the pole structure of the $\zeta$-function associated to the Hamiltonian $H$ of a quantum mechanical particle living in the half-line $\mathbf{R}^+$, subject to the singular potential $g x^{-2}+x^2$. We show that $H$ admits nontrivial self-adjoint extensions (SAE) in a given range of values of the parameter $g$. The $\zeta$-functions of these operators present poles which depend on $g$ and, in general, do not coincide with half an integer (they can even be irrational). The corresponding residues depend on the SAE considered.Comment: 12 pages, 1 figure, RevTeX. References added. Version to appear in Jour. Phys. A: Math. Ge

Path Integral Approach for Superintegrable Potentials on Spaces of Non-constant Curvature: II. Darboux Spaces DIII and DIV

This is the second paper on the path integral approach of superintegrable systems on Darboux spaces, spaces of non-constant curvature. We analyze in the spaces \DIII and \DIV five respectively four superintegrable potentials, which were first given by Kalnins et al. We are able to evaluate the path integral in most of the separating coordinate systems, leading to expressions for the Green functions, the discrete and continuous wave-functions, and the discrete energy-spectra. In some cases, however, the discrete spectrum cannot be stated explicitly, because it is determined by a higher order polynomial equation. We show that also the free motion in Darboux space of type III can contain bound states, provided the boundary conditions are appropriate. We state the energy spectrum and the wave-functions, respectively

Muscle Performance Changes with Age in Active Women

The purpose of this study was to examine age-related differences in muscle performance in women divided into young (YW, 20–39 years, n = 29) middle-aged (MAW, 40–59 years, n = 33), and older (OW, ≥60 years, n = 40) age groups. Methods: Hand grip strength, vertical jump performance, and knee extensor (KE) strength (0 deg/s, 60 deg/s, and 240 deg/s), speed of movement (SoM; at 1 Nm, 20%, 40%, and 60% isometric strength), and endurance (30-repetition test at 60 degs/s and 240 deg/s) were assessed. Computed tomography-acquired muscle cross-sectional area (mCSA) was measured and included to determine specific strength (KE strength/mCSA). Results: Hand grip strength was similar across groups, while jump performance declined with age (YW and MAW \u3e OW, p \u3c 0.001). KE strength declined significantly with age (all conditions p \u3c 0.01), while specific strength was similar across groups. SoM was significantly higher for YW and MAW compared to OW (both p \u3c 0.01). An age × velocity interaction revealed YW KE endurance was similar between conditions, whereas MAW and OW displayed significantly better endurance during the 60 deg/s condition. OW displayed impaired KE endurance at 240 deg/s (vs. YW and MAW, p \u3c 0.01) but improved at 60 deg/s (vs. YW, p \u3c 0.01). Dynamic torque decline increased with age (YW \u3c OW, p = 0.03) and was associated with intramuscular adipose tissue (r = 0.21, p = 0.04). Conclusions: Performance declines were most evident among OW, but few performance deficits had emerged in MAW. Interestingly, strength declines disappeared after normalizing to mCSA and endurance appears to be velocity-dependent

Exact expression for the diffusion propagator in a family of time-dependent anharmonic potentials

We have obtained the exact expression of the diffusion propagator in the time-dependent anharmonic potential $V(x,t)={1/2}a(t)x^2+b\ln x$. The underlying Euclidean metric of the problem allows us to obtain analytical solutions for a whole family of the elastic parameter a(t), exploiting the relation between the path integral representation of the short time propagator and the modified Bessel functions. We have also analyzed the conditions for the appearance of a non-zero flow of particles through the infinite barrier located at the origin (b<0).Comment: RevTex, 19 pgs. Accepted in Physical Review

Search for the exotic Θ+\Theta^+ resonance in the NOMAD experiment

A search for exotic Theta baryon via Theta -> proton +Ks decay mode in the NOMAD muon neutrino DIS data is reported. The special background generation procedure was developed. The proton identification criteria are tuned to maximize the sensitivity to the Theta signal as a function of xF which allows to study the Theta production mechanism. We do not observe any evidence for the Theta state in the NOMAD data. We provide an upper limit on Theta production rate at 90% CL as 2.13 per 1000 of neutrino interactions.Comment: Accepted to European Physics Journal

What do stroke survivors' value about participating in research and what are the most important research problems related to stroke or transient ischemic attack (TIA)? A survey

Background: Recruitment to stroke clinical trials is challenging, but consumer registers can facilitate participation. Researchers need to understand the key factors that facilitate trial involvement and improve consumer partnerships to identify what research topics important to stroke and transient ischemic attack (TIA) survivors and their carers. We aimed to examine i) the experience of being involved in a stroke research register, and ii) the priorities for stroke research from the perspective of stroke survivors. Methods: Online and paper-based surveys were sent directly to members of a stroke register and disseminated online. Multiple choice questions were reported as counts and percentages and open-ended questions were thematically analysed using Braun and Clarke’s 6-stage process. Results: Of 445 survey respondents, 154 (38%) were a member of the Stroke Research Register. The most frequently reported reason for research participation was to help others in the future. Respondents reported they were less likely to take part in research if the research question was not relevant to them, if transport was an issue, or because they lacked time. The most important research problems reported were targeting specific impairments including recovery of movement, fatigue, and aphasia, improvement of mental health services, and increased support for carers. Conclusions: Recruitment to trials may be improved by research registers if an inclusive research culture is fostered, in which consumers feel valued as members of a community, have direct and timely access to research findings and the opportunity to be meaningfully involved in research around the problems that consumers find most important.Ishanka Weerasekara, Jasmine Baye, Meredith Burke, Gary Crowfoot, Gillian Mason, Rachael Peak, Dawn Simpson, Frederick Rohan Walker, Michael Nilsson, Michael Pollack, and Coralie Englis