Low-noise microwave polarimeter

Two quarterwave-plate polarizers inserted between rotary waveguide joints transform received signals from arbitrary linear to circular polarizations and then from circular to fixed linear polarizations. Fixed linear polarizations are applied to amplifiers and filters in usual fashion

Community Service to the Elderly A Service-Learning Model: Guidelines for Replication

At the University of Pittsburgh, Generations Together, an Intergenerational Studies Program develops programs that bring young and old together in ways that benefit both generations. The University Challenge for Excellence Program (DCEP) works with entering students who are often first generation, mostly African-American, and who may be in need of special assistance during their first year. UCEP seeks ways to raise their self esteem, give them a sense of purpose, connect them to the University, and ultimately to retain them at Pitt through graduation. In 1994, these two university programs joined together with the Housing Authority of the City of Pittsburgh (HACP) to develop a program that addresses the needs of UCEP students and older adults in Pittsburgh. The result of this collaboration is an intergenerational community service project which was funded by the U. S. Department of Education\u27s Fund for the Improvement of Post-Secondary Education (FIPSE)

First exit times and residence times for discrete random walks on finite lattices

In this paper, we derive explicit formulas for the surface averaged first exit time of a discrete random walk on a finite lattice. We consider a wide class of random walks and lattices, including random walks in a non-trivial potential landscape. We also compute quantities of interest for modelling surface reactions and other dynamic processes, such as the residence time in a subvolume, the joint residence time of several particles and the number of hits on a reflecting surface.Comment: 19 pages, 2 figure

Dielectric resonances of ordered passive arrays

The electrical and optical properties of ordered passive arrays, constituted of inductive and capacitive components, are usually deduced from Kirchhoff's rules. Under the assumption of periodic boundary conditions, comparable results may be obtained via an approach employing transfer matrices. In particular, resonances in the dielectric spectrum are demonstrated to occur if all eigenvalues of the transfer matrix of the entire array are unity. The latter condition, which is shown to be equivalent to the habitual definition of a resonance in impedance for an array between electrodes, allows for a convenient and accurate determination of the resonance frequencies, and may thus be used as a tool for the design of materials with a specific dielectric response. For the opposite case of linear arrays in a large network, where periodic boundary condition do not apply, several asymptotic properties are derived. Throughout the article, the derived analytic results are compared to numerical models, based on either Exact Numerical Renormalisation or the spectral method.Comment: 12 pages, 12 figure

A cosmological model in Weyl-Cartan spacetime

We present a cosmological model for early stages of the universe on the basis of a Weyl-Cartan spacetime. In this model, torsion $T^{\alpha}$ and nonmetricity $Q_{\alpha \beta}$ are proportional to the vacuum polarization. Extending earlier work of one of us (RT), we discuss the behavior of the cosmic scale factor and the Weyl 1-form in detail. We show how our model fits into the more general framework of metric-affine gravity (MAG).Comment: 19 pages, 5 figures, typos corrected, uses IOP style fil

The Clusters AgeS Experiment (CASE). II. The Eclipsing Blue Straggler OGLEGC-228 in the Globular Cluster 47 Tuc

We use photometric and spectroscopic observations of the eclipsing binary OGLEGC-228 (V228) to derive the masses, radii, and luminosities of the component stars. Based on measured systemic velocity, proper motion and distance, the system is a blue straggler member of the globular cluster 47 Tuc. Our analysis shows that V228 is a semi-detached Algol. We obtain M=1.512 +/- 0.022 Msun, R=1.357 +/- 0.019 Rsun, L=7.02 +/- 0.050 Lsun for the hotter and more luminous primary component and M=0.200 +/- 0.007 Msun, R=1.238 +/- 0.013 Rsun, L=1.57 +/- 0.09 Lsun for the Roche lobe filling secondary.Comment: 19 pages, 5 figures, AJ, in pres

Cosmological Models with Shear and Rotation

Cosmological models involving shear and rotation are considered, first in the General Relat ivistic and then in the Newtonian framework with the aim of investigating singularities in them by using numerical and analytical techniques. The dynamics of these rotating models ar e studied. It is shown that singularities are unavoidable in such models and that the centr ifugal force arising due to rotation can never overcome the gravitational and shearing forc e over a length of time.Comment: 17 pages, 6 figures Journal Ref: J. Astrophys. Astr. (1999) 20, 79-8

Conservation of the maned wolf (Chrysocyon brachyurus) : carnivore and people relationships in the southeast of Brazil

Maned wolves are endangered carnivores endemic to Brazil. This research aimed to compare the attitudes of interest groups towards the conservation of the maned wolf in urban and rural areas; to investigate how such attitudes may influence the maned wolf's status and conservation; and to recommend ways to incorporate such knowledge into strategies to conserve both wolf and habitat. The methodology used questionnaires and interviews. Questionnaires targeted people living in the neighbourhood of conservation areas, staff and students (year 8 and sixth-form) of local schools; staff and visitors to conservation areas and zoos in three main research locations: Greater São Paulo, the Low Mogiana region and São Carlos city. Other conservation areas and zoos within the São Paulo state contributed further data. The relationship between socio-demographic factors and attitudes towards the maned wolf conservation was also investigated to identify the most positive and negative profiles of respondents. Overall, results indicate a lack of antagonism between urban and rural populations. Results suggest that negative attitudes towards the maned wolf related to: misconceptions about feeding habits and to a lack of clear differentiation between the maned wolf and Canis lupus; perceptions of threat connected to the presence of the maned wolf on people's properties; and possibly values undermining local wildlife. Results, however, consistently indicated local people's tolerance towards the species and towards occasional predation events. Results also indicate discrepancies existing between bio/education professionals' expectations of local people's attitudes and the actual attitudes displayed by the latter. Recommendations addressed misconceptions and values regarding the maned wolf, inclusion of the local community and their issues, and relationships between interest groups for the benefit of maned wolf conservation. The positive attitudes of a majority towards the maned wolf suggest they may support actions favourable to the species and maintain their position in case of conflict. However, further investigation is advised into local people's awareness of the causes of the decline of the maned wolf and of how their behaviour may affect populations of wolves.EThOS - Electronic Theses Online ServiceGBUnited Kingdo