Study of an advanced transport airplane design concept known as Flatbed

The design concept and configuration of the Flatbed transport aircraft are presented. The Flatbed configuration combines into one frame, the ability to haul cargo, virtually unrestrained by cross sectional dimensions of the fuselage. The feasibility and capability of the Flatbed is discussed in depth

Initiating a Swine Production Medicine Program

The role of veterinary medicine in the United States food animal industry is currently changing. Veterinarians are no longer viewed as mere providers of clinical services such as healing individual sick animals. This traditional role is being replaced with planned animal health programs for the entire herd. The objective of production medicine is to consistently maintain overall animal health and increase production cost-effectively to attain optimum economic returns for the producer. This holistic approach to animal health and production reduces the importance of specific infectious agents per se, and concentrates on the effect of interactions of these agents, environment, nutrition, genetics, and management on animal performance. Attempting to assimilate all these factors, in hopes of developing specific recommendations for the producer, may seem overwhelming when starting a production medicine program. This case report will illustrate the diagnostic procedures used to evaluate these factors when initiating a program for a swine herd in central Iowa

Simulation Of Human Jumping - Task Alteration

Similar human motions are often grouped together into a single movement class. In jumping, the question of similarity in control and coordination of different tasks within a movement class has been addressed by altering the direction of maximal effort jumps between vertical and horizontal (Jensen & Phillips, 1991). Other researchers have studied vertical jumping using computer simulations (Pandy & Zajac, 1991; van Soest et al., 1993), but have not addressed the issue of modifying the jumping task. The purpose of the present study was to investigate the effect of task alteration on forward .dynamic simulations of jumping. The simulation model was comprised of 4 linked rigid segments (Fig. 1). Segmental motion was controlled by 3 torque generators defined with pre-set magnitudes and activation time constants. All jumps began from a static posture with all torques set to zero. Each jumping performance was dictated by the onset times of each torque generator. The choice of task was specified by one of two objective functions: 1) vertical height, or 2) horizontal distance. The optimization algorithm searched for the pattern of activation onset times for the 3 torque generators which maximized each objective function. A variety of tests were performed to compare the model's optimal vertical and horizontal jumping performance, and the underlying coordination of torque generation. With the set of initial conditions shown in Fig. la (00 = (1.0,-0.7,1.1,-0.8}), the model's maximum height was 1.814 m, with a forward displacement of 0.39 m. For the optimal forward jump the displacement increased to only 0.73 m. However, by changing the initial posture (00 = (0.8,-1.0,0.8,-1.0}) the optimal forward jump was improved to 1.87 m (Fig. lb), but the optimal vertical jump was reduced to 1.465 m. The relative magnitude of onset times varied substantially between the two optimal jumps. For the conditions studied, the order of onset times does not follow the proximo-distal sequence often .proported for humans, and the relative timing of joint torques changes with task. The results illustrate the dependence of the optimal solution on initial conditions. Further work will examine the relations between initial conditions, coordination and perfommance

Stringent constraint on the scalar-neutrino coupling constant from quintessential cosmology

An extremely light ($m_{\phi} \ll 10^{-33} {\rm eV}$), slowly-varying scalar field $\phi$ (quintessence) with a potential energy density as large as 60% of the critical density has been proposed as the origin of the accelerated expansion of the Universe at present. The interaction of this smoothly distributed component with another predominately smooth component, the cosmic neutrino background, is studied. The slow-roll approximation for generic $\phi$ potentials may then be used to obtain a limit on the scalar-neutrino coupling constant, found to be many orders of magnitude more stringent than the limits set by observations of neutrinos from SN 1987A. In addition, if quintessential theory allows for a violation of the equivalence principle in the sector of neutrinos, the current solar neutrino data can probe such a violation at the 10^{-10} level.Comment: 7 pages, MPLA in press, some parts disregarded and a footnote adde

Spectroscopy of Giant Stars in the Pyxis Globular Cluster

The Pyxis globular cluster is a recently discovered globular cluster that lies in the outer halo (R_{gc} ~ 40 kpc) of the Milky Way. Pyxis lies along one of the proposed orbital planes of the Large Magellanic Cloud (LMC), and it has been proposed to be a detached LMC globular cluster captured by the Milky Way. We present the first measurement of the radial velocity of the Pyxis globular cluster based on spectra of six Pyxis giant stars. The mean heliocentric radial velocity is ~ 36 km/sec, and the corresponding velocity of Pyxis with respect to a stationary observer at the position of the Sun is ~ -191 km/sec. This radial velocity is a large enough fraction of the cluster's expected total space velocity, assuming that it is bound to the Milky Way, that it allows strict limits to be placed on the range of permissible transverse velocities that Pyxis could have in the case that it still shares or nearly shares an orbital pole with the LMC. We can rule out that Pyxis is on a near circular orbit if it is Magellanic debris, but we cannot rule out an eccentric orbit associated with the LMC. We have calculated the range of allowed proper motions for the Pyxis globular cluster that result in the cluster having an orbital pole within 15 degrees of the present orbital pole of the LMC and that are consistent with our measured radial velocity, but verification of the tidal capture hypothesis must await proper motion measurement from the Space Interferometry Mission or HST. A spectroscopic metallicity estimate of [Fe/H] = -1.4 +/- 0.1 is determined for Pyxis from several spectra of its brightest giant; this is consistent with photometric determinations of the cluster metallicity from isochrone fitting.Comment: 22 pages, 5 figures, aaspp4 style, accepted for publication in October, 2000 issue of the PAS

Anisotropy of the Cosmic Neutrino Background

The cosmic neutrino background (CNB) consists of low-energy relic neutrinos which decoupled from the cosmological fluid at a redshift z ~ 10^{10}. Despite being the second-most abundant particles in the universe, direct observation remains a distant challenge. Based on the measured neutrino mass differences, one species of neutrinos may still be relativistic with a thermal distribution characterized by the temperature T ~ 1.9K. We show that the temperature distribution on the sky is anisotropic, much like the photon background, experiencing Sachs-Wolfe and integrated Sachs-Wolfe effects.Comment: 5 pages, 2 figures / updated references, discussion of earlier wor