Some Applications of Detailed Wind Profile Data to Launch Vehicle Response Problems

The response of a launch vehicle to a number of detailed wind profiles has been determined. The wind profiles were measured by two techniques which are briefly described. One of these techniques uses an angle-of-attack sensor in conjunction with guidance data to measure the wind profile traversed by some particular launch vehicle. The other wind-measuring technique is a photographic triangulation method, whereby two cameras take simultaneous pictures of a vertical trail of smoke left by a launch vehicle or sounding rocket. The response of a vehicle flying these detailed profiles is compared with the response of the same vehicle flying through balloon-measured profiles. The response to the detailed wind profiles, relative t o the balloon-measured profiles, is characterized by the large excitation of the rigid pitch and elastic bending modes. This is found to cause higher loads on the launch vehicle structure. Established design criteria which utilize balloon measured wind profiles have arbitrarily accounted-for this increased load by adding a load due to some type of discrete gust

Charged particle concepts for fog dispersion

Charged particle techniques hold promise for dispersing warm fog in the terminal area of commercial airports. This report focuses on features of the charged particle technique which require further study. The basic physical principles of the technique and the major verification experiments carried out in the past are described. The fundamentals of the nozzle operation are given. The nozzle characteristics and the theory of particle charging in the nozzle are discussed, including information from extensive literature on electrostatic precipitation relative to environmental pollution control and a description of some preliminary reported analyses on the jet characteristics and interaction with neighboring jets. The equation governing the transfer of water substances and of electrical charge is given together with a brief description of several semi-empirical, mathematical expressions necessary for the governing equations. The necessary ingredients of a field experiment to verify the system once a prototype is built are described

Designing Primary Prevention for People Living with HIV

Today, there are new reasons for a sharper focus on prevention for people living with HIV. Growing numbers of people with the disease are living more healthy, sexual lives. Recent evidence suggests that risk taking among both HIV-positive and negative people is increasing. After nearly two decades of life in the shadow of AIDS, communities are growing weary of traditional prevention messages and many people are openly grappling with difficult questions of intimacy and sex. Increasingly, people living with HIV also face multiple complex economic and substance abuse challenges that complicate prevention efforts.There is an urgent need -- and sufficient expertise -- to move forward with prevention campaigns focused on helping people living with HIV and AIDS avoid passing their infection along to others. Numerous innovative interventions for people with HIV show promise, including:a social marketing campaign for gay men and a five-session group intervention for women living with HIV in Massachusetts,a chat line for positives and a group session program for Latinas/Latinos in Los Angeles,Internet chat room interventions in Atlanta,a group session for gay Asian American-Pacific Islander Americans living with HIV in San Francisco, andPrevention Case Management programs newly funded by the Centers for Disease Control

The Stability of an Isotropic Cosmological Singularity in Higher-Order Gravity

We study the stability of the isotropic vacuum Friedmann universe in gravity theories with higher-order curvature terms of the form $(R_{ab}R^{ab})^{n}$ added to the Einstein-Hilbert Lagrangian of general relativity on approach to an initial cosmological singularity. Earlier, we had shown that, when $$, a special isotropic vacuum solution exists which behaves like the radiation-dominated Friedmann universe and is stable to anisotropic and small inhomogeneous perturbations of scalar, vector and tensor type. This is completely different to the situation that holds in general relativity, where an isotropic initial cosmological singularity is unstable in vacuum and under a wide range of non-vacuum conditions. We show that when $n\neq 1$, although a special isotropic vacuum solution found by Clifton and Barrow always exists, it is no longer stable when the initial singularity is approached. We find the particular stability conditions under the influence of tensor, vector, and scalar perturbations for general $n$ for both solution branches. On approach to the initial singularity, the isotropic vacuum solution with scale factor $a(t)=t^{P_{-}/3}$ is found to be stable to tensor perturbations for $0.5<n< 1.1309$ and stable to vector perturbations for $0.861425 < n \leq 1$, but is unstable as $t \to 0$ otherwise. The solution with scale factor $a(t)=t^{P_{+}/3}$ is not relevant to the case of an initial singularity for $n>1$ and is unstable as $t \to 0$ for all $n$ for each type of perturbation.Comment: 25 page

Double transverse spin asymmetries in vector boson production

We investigate a helicity non-flip double transverse spin asymmetry in vector boson production in hadron-hadron scattering, which was first considered by Ralston and Soper at the tree level. It does not involve transversity functions and in principle also arises in W-boson production for which we present the expressions. The asymmetry requires observing the transverse momentum of the vector boson, but it is not suppressed by explicit inverse powers of a large energy scale. However, as we will show, inclusion of Sudakov factors causes suppression of the asymmetry, which increases with energy. Moreover, the asymmetry is shown to be approximately proportional to x_1 g_1(x_1) x_2 \bar g_1(x_2), which gives rise to additional suppression at small values of the light cone momentum fractions. This implies that it is negligible for Z or W production and is mainly of interest for \gamma^* at low energies. We also compare the asymmetry with other types of double transverse spin asymmetries and discuss how to disentangle them.Comment: 12 pages, Revtex, 2 Postscript figures, uses aps.sty, epsf.sty; figures replaced, a few minor other correction

Applying machine learning to the problem of choosing a heuristic to select the variable ordering for cylindrical algebraic decomposition

Cylindrical algebraic decomposition(CAD) is a key tool in computational algebraic geometry, particularly for quantifier elimination over real-closed fields. When using CAD, there is often a choice for the ordering placed on the variables. This can be important, with some problems infeasible with one variable ordering but easy with another. Machine learning is the process of fitting a computer model to a complex function based on properties learned from measured data. In this paper we use machine learning (specifically a support vector machine) to select between heuristics for choosing a variable ordering, outperforming each of the separate heuristics.Comment: 16 page

Critical properties of the half-filled Hubbard model in three dimensions

By means of the dynamical vertex approximation (D$\Gamma$A) we include spatial correlations on all length scales beyond the dynamical mean field theory (DMFT) for the half-filled Hubbard model in three dimensions. The most relevant changes due to non-local fluctuations are: (i) a deviation from the mean-field critical behavior with the same critical exponents as for the three dimensional Heisenberg (anti)-ferromagnet and (ii) a sizable reduction of the N\'eel temperature ($T_N$) by $\sim 30$ for the onset of antiferromagnetic order. Finally, we give a quantitative estimate of the deviation of the spectra between D$\Gamma$A and DMFT in different regions of the phase-diagram.Comment: 4 pages, 3 figures; accepted for publication in Phys. Rev. Let

Single spin asymmetries in DIS

We consider possible mechanisms for single spin asymmetries in inclusive Deep Inelastic Scattering (DIS) processes with unpolarized leptons and transversely polarized nucleons. Tests for the effects of non-zero \bfk_\perp, for the properties of spin dependent quark fragmentations and for quark helicity conservation are suggested.Comment: 5 pages, LaTeX, no figures. Revised version, to be published in Phys. Rev. D. Some equations and statements added to clarify text and notation