An overview of the communications technology satellite project: Executive summary

An overview of the Communications Technology Satellite (CTS) project, a joint venture between NASA and the Canadian Department of Communications is given. A brief technical description of the CTS spacecraft and its cognate hardware and operations, a history of the CTS project, and a list of the CTS experiments and demonstrations conducted during the course of the project are given

Management of Four Alfalfa Varieties to Control Damage from Potato Leafhoppers

The main purpose of this study was to obtain information on forage yield and quality of four alfalfa (Medicago sativa L.) varieties that differed in level of resistance to potato leafhopper (Empoasca fabae Harris) yellowing, when cut at three stages of growth in the second and third cuttings in field plots, with and without insecticide application. The stages of growth were bud, 1/10, and full bloom. Other purposes included study of the same varieties in field cages manually infested at 20, 40, and 60 adult leafhoppers/square yard, and in supplemental cuttings of field plots under high natural infestation levels

Climate Change and Malaria in Canada: A Systems Approach

This article examines the potential for changes in imported and autochthonous malaria incidence in Canada as a consequence of climate change. Drawing on a systems framework, we qualitatively characterize and assess the potential direct and indirect impact of climate change on malaria in Canada within the context of other concurrent ecological and social trends. Competent malaria vectors currently exist in southern Canada, including within this range several major urban centres, and conditions here have historically supported endemic malaria transmission. Climate change will increase the occurrence of temperature conditions suitable for malaria transmission in Canada, which, combined with trends in international travel, immigration, drug resistance, and inexperience in both clinical and laboratory diagnosis, may increase malaria incidence in Canada and permit sporadic autochthonous cases. This conclusion challenges the general assumption of negligible malaria risk in Canada with climate change

Elastic cavitation, tube hollowing, and differential growth in plants and biological tissues

Elastic cavitation is a well-known physical process by which elastic materials under stress can open cavities. Usually, cavitation is induced by applied loads on the elastic body. However, growing materials may generate stresses in the absence of applied loads and could induce cavity opening. Here, we demonstrate the possibility of spontaneous growth-induced cavitation in elastic materials and consider the implications of this phenomenon to biological tissues and in particular to the problem of schizogenous aerenchyma formation

Energy Spectrum Evolution of a Diffuse Field in Elastic Body Caused by Weak Nonlinearity

We study the evolution of diffuse elastodynamic spectral energy density under the influence of weak nonlinearity. It is shown that the rate of change of this quantity is given by a convolution of the linear energy at two frequencies. Quantitative estimates are given for sample aluminum and fused silica blocks of experimental interest.Comment: 9 pages, 3 figures; revised for better presentatio

Mass and Angular Momentum Transfer in the Massive Algol Binary RY Persei

We present an investigation of H-alpha emission line variations observed in the massive Algol binary, RY Per. We give new radial velocity data for the secondary based upon our optical spectra and for the primary based upon high dispersion UV spectra. We present revised orbital elements and an estimate of the primary's projected rotational velocity (which indicates that the primary is rotating 7 times faster than synchronous). We use a Doppler tomography algorithm to reconstruct the individual primary and secondary spectra in the region of H-alpha, and we subtract the latter from each of our observations to obtain profiles of the primary and its disk alone. Our H-alpha observations of RY Per show that the mass gaining primary is surrounded by a persistent but time variable accretion disk. The profile that is observed outside-of-eclipse has weak, double-peaked emission flanking a deep central absorption, and we find that these properties can be reproduced by a disk model that includes the absorption of photospheric light by the band of the disk seen in projection against the face of the star. We developed a new method to reconstruct the disk surface density distribution from the ensemble of H-alpha profiles observed around the orbit, and this method accounts for the effects of disk occultation by the stellar components, the obscuration of the primary by the disk, and flux contributions from optically thick disk elements. The resulting surface density distribution is elongated along the axis joining the stars, in the same way as seen in hydrodynamical simulations of gas flows that strike the mass gainer near trailing edge of the star. This type of gas stream configuration is optimal for the transfer of angular momentum, and we show that rapid rotation is found in other Algols that have passed through a similar stage.Comment: 39 pages, 12 figures, ApJ in press, 2004 June 20 issu

First Results from the CHARA Array. II. A Description of the Instrument

The CHARA Array is a six 1-m telescope optical/IR interferometric array located on Mount Wilson California, designed and built by the Center for High Angular Resolution Astronomy of Georgia State University. In this paper we describe the main elements of the Array hardware and software control systems as well as the data reduction methods currently being used. Our plans for upgrades in the near future are also described

The Cauchy problem for a class of two-dimensional nonlocal nonlinear wave equations governing anti-plane shear motions in elastic materials

This paper is concerned with the analysis of the Cauchy problem of a general class of two-dimensional nonlinear nonlocal wave equations governing anti-plane shear motions in nonlocal elasticity. The nonlocal nature of the problem is reflected by a convolution integral in the space variables. The Fourier transform of the convolution kernel is nonnegative and satisfies a certain growth condition at infinity. For initial data in $L^{2}$ Sobolev spaces, conditions for global existence or finite time blow-up of the solutions of the Cauchy problem are established.Comment: 15 pages. "Section 6 The Anisotropic Case" added and minor changes. Accepted for publication in Nonlinearit

Paradox in the pursuit of a critical theorization of the development of self in family relationships

This article starts with my dissatisfaction with the post-structuralist treatment of the production of subjectivity within regulatory discourses and practices due to its neglect of psychological processes. Taking starting points from within the history set out in the previous article, it highlights the paradox for critical psychologists like myself involved in both applying a post-structuralist critique to 'psy' discourses and trying to theorize subjectivity in a way that goes beyond the dualism of individual and society, of psychology and sociology. The relational, or intersubjective, approach to self that originates in object relations psychoanalysis as it emerged in the mid-20th-century UK is central to both of these activities; object of the former and resource for the latter. I explore the paradox that this creates for critical psychology, both epistemological and ontological. In aiming to provide a psycho-social account of self in family relationships, I deploy the radical conceptualisation of intersubjectivity initiated in British object relations theory as a way of going beyond both the individualized self and the neglect of psychological processes in constructionist theorizing subjectivity

Alfalfa Insect Management Studies 1971-77

Three tests in southwestern Nebraska during 1971 and 1972 evaluated insecticides against the army cutworm. Adult alfalfa weevils did not damage new second growth alfalfa in a small plot study during a 3-year period (1973-1975) at Gothenburg, NE. However, excellent control of larval alfalfa weevils was obtained. These results indicated a need to establish economic threshold levels for the alfalfa weevil in Nebraska to prevent unnecessary use of insecticides. Four tests to control the alfalfa weevil with registered insecticides verified the efficacy of these materials under Nebraska conditions. A series of tests conducted during 1975 at the Mead Field Laboratory were designed to evaluate plant resistance, cultural practices and insecticides. The use of alfalfa varieties with resistance to various insect pests of alfalfa appeared to be an ideal control method. During 1975-1977, a test was conducted each year at the Mead Field Laboratory to evaluate new experimental insecticides against the alfalfa weevil and other pest insects of alfalfa grown for forage. A number of the new insecticides showed promise against the alfalfa weevil and the pea aphid