Station-keeping guidance

The station-keeping guidance system is described, which is designed to automatically keep one orbiting vehicle within a prescribed zone fixed with respect to another orbiting vehicle. The active vehicle, i.e. the one performing the station-keeping maneuvers, is referred to as the shuttle. The other passive orbiting vehicle is denoted as the workshop. The passive vehicle is assumed to be in a low-eccentricity near-earth orbit. The primary navigation sensor considered is a gimballed tracking radar located on board the shuttle. It provides data on relative range and range rate between the two vehicles. Also measured are the shaft and trunnion axes gimbal angles. An inertial measurement unit (IMU) is provided on board the orbiter. The IMU is used at all times to provide an attitude reference for the vehicle. The IMU accelerometers are used periodically to monitor the velocity-correction burns applied to the shuttle during the station-keeping mode. The guidance system is capable of station-keeping the shuttle in any arbitrary position with respect to the workshop by periodically applying velocity-correction pulses to the shuttle

Apparatus for measuring thermal conductivity Patent

Development of apparatus for measuring thermal conductivit

Spectra generated by a confined softcore Coulomb potential

Analytic and approximate solutions for the energy eigenvalues generated by a confined softcore Coulomb potentials of the form a/(r+\beta) in d>1 dimensions are constructed. The confinement is effected by linear and harmonic-oscillator potential terms, and also through `hard confinement' by means of an impenetrable spherical box. A byproduct of this work is the construction of polynomial solutions for a number of linear differential equations with polynomial coefficients, along with the necessary and sufficient conditions for the existence of such solutions. Very accurate approximate solutions for the general problem with arbitrary potential parameters are found by use of the asymptotic iteration method.Comment: 17 pages, 2 figure

The effect of lutein intake on macular pigment density

Age related macular degeneration (AMD) is a sight-threatening retinal disease found predominately in men and women over 65 years of age. AMD is thought to result from oxidative damage to the retina triggered by UV and blue light. Recent studies have suggested the onset and progression of AMD may be delayed by diet supplementation with antioxidants like lutein and zeaxanthin which are found in the macular area as the macular pigments. The density of the macular pigments can be quantified using heterochromic flicker photometry. In this study, 29 optometry students, between the ages of 22 and 30, were divided into groups. Group one, the control group, experienced no intervention, group two took 4 mg of lutein daily for 30 days and group three ingested 0.75 ounces of spinach daily for 30 days. The macular pigment density was assessed at baseline before any intervention, after 30 days of supplementation and again 30 days after discontinuing supplementation. Neither lutein nor spinach increased the macular pigment density in this study

Prompt photon hadroproduction at high energies in the k_T-factorization approach

We consider the prompt photon production at high energy hadron colliders in the framework of k_T-factorization approach. The unintegrated quark and gluon distributions in a proton are determined using the Kimber-Martin-Ryskin prescription. The conservative error analisys is performed. We investigate both inclusive prompt photon and prompt photon and associated muon production rates. In Standard Model such events come mainly due to Compton scattering process where the final heavy (charm or bottom) quark produces a muon. The theoretical results are compared with recent experimental data taken by the D0 and CDF collaborations at Fermilab Tevatron. Our analysis also covers the azimuthal correlations between produced prompt photon and muon which can provide an important information about non-collinear parton evolution in a proton. Finally, we extrapolate the theoretical predictions to CERN LHC energies.Comment: 27 pages, 13 figure

The Relationship between Neighborhood Food Environment and Food Store Choice on Purchasing Habits among SNAP and Lower Income Households, USDA FoodAPS Data

The objective of the study was to determine relationship between neighborhood food store availability, store choice and food purchasing habits among Supplemental Nutrition Assistance Program (SNAP) participating households. The study sample consisted of SNAP households (n=1581) and low income households participating in the USDA\u27s National Household Food Acquisition and Purchase Survey (FoodAPS) a nationally representative cross-sectional survey of American households with household food purchases and acquisitions data. Main Outcomes: 1) Food purchasing choices (sugar-sweetened beverages, fruits and vegetables, snacks, water, and milk) obtained from store receipts over a one-week period; 2) food shopping activities was obtained from a log book of where food was purchased over a one-week period. Key findings indicated those SNAP households within 1 mile of a supermarket had higher odds of shopping at a supermarket (2.05 OR [95% CI 1.34, 3.15]) compared to those without a supermarket. Shopping at a supermarket was associated with greater odds of purchasing water and low-calorie beverages (OR 1.69 [95% CI 1.12, 2.54]) and fruits and vegetables (OR 2.50 (95% CI 1.52, 4.11]) compared to not shopping at supermarket among SNAP households. Additionally, a fractional multinomial logit analysis (n=4,664) similarly found that close proximity to superstores or supermarkets increases the share of weekly food purchases made there, and that car access increases purchases made at restaurants while decreasing purchases made at other food shopping venues. Findings suggest that policies aiming to improve food purchasing habits among SNAP need to consider how to situate stores where SNAP households will choose to shop

Predictive markers for humoral influenza vaccine response in patients with common variable immunodeficiency (CVID)

BACKGROUND: A subgroup of patients with common variable immunodeficiencies (CVID) responds to vaccination. The aim of the study was to try to identify predictive markers for those who developed a humoral immune response after influenza vaccination. METHODS: 48 patients with CVID (29 females, 19 males, mean age 59.4 years) were vaccinated with the A(H1N1) influenza vaccine Pandemrix® and boosted after one month. Blood samples were collected prior to each vaccination and two months later. Patients with a 4-fold titer increase of the hemagglutinin inhibition test (≥ 1:40) were considered responders and compared to non-responders for clinical, immunological and genetic markers. RESULTS: Eight (16.7%) patients responded to the vaccination. A significantly higher proportion of the responders, who showed a Euroclass SmB-Trnorm21norm profile (p=0.03) with a post-germinal center B cell pattern (p=0.04) in blood, suffered from enteropathies (p=0.04) as compared to non-responders. Bronchiectasis on the other hand, was exclusively found among non-responders (n=7), as was autoimmune cytopenia (n=5). Non-responders with a Euroclass SmB-21lowTrnorm profile (p=0.02), had a significantly higher prevalence of progressive antibody deficiency (p=0.048) and, at diagnosis, a higher mean serum IgM level (p=0.03), a lower mean serum IgG1 level (p=0.007), an expansion of absolute counts of cytotoxic CD8+ T-cells (p=0.033) and an increased proportion of memory CD8+ T-cells (p=0.044) in blood. CVID associated HLA markers were not detected in non-responders (p=0.03). CONCLUSION: About one-fifth of the CVID patients achieved protective antibody levels after A(H1N1) vaccination and selected clinical and immunological markers were identified that may predict a positive outcome of influenza vaccination

Small-x Dipole Evolution Beyond the Large-N_c Limit

We present a method to include colour-suppressed effects in the Mueller dipole picture. The model consistently includes saturation effects both in the evolution of dipoles and in the interactions of dipoles with a target in a frame-independent way. When implemented in a Monte Carlo simulation together with our previous model of energy--momentum conservation and a simple dipole description of initial state protons and virtual photons, the model is able to reproduce to a satisfactory degree both the gamma*-p cross sections as measured at HERA as well as the total p-p cross section all the way from ISR energies to the Tevatron and beyond

Spectral characteristics for a spherically confined -1/r + br^2 potential

We consider the analytical properties of the eigenspectrum generated by a class of central potentials given by V(r) = -a/r + br^2, b>0. In particular, scaling, monotonicity, and energy bounds are discussed. The potential $V(r)$ is considered both in all space, and under the condition of spherical confinement inside an impenetrable spherical boundary of radius R. With the aid of the asymptotic iteration method, several exact analytic results are obtained which exhibit the parametric dependence of energy on a, b, and R, under certain constraints. More general spectral characteristics are identified by use of a combination of analytical properties and accurate numerical calculations of the energies, obtained by both the generalized pseudo-spectral method, and the asymptotic iteration method. The experimental significance of the results for both the free and confined potential V(r) cases are discussed.Comment: 16 pages, 4 figure