Health/education telecommunications experiment

The use of ATS 6 spacecraft in a general telecommunication link for the health/education experiment demonstrates the feasibility of the small receiver-only terminal consisting of a ten foot diameter antenna located on a three-legged mount. The terminal is capable of 0 to 70 degrees elevation, course adjustment, and a plus or minus 5 degree elevation vernier adjustment. Its tuned radio frequency receiver utilizes a cavity back dipole feed and a preamplifier. The indoor unit provides further RF gain and drives a wideband limiter-discriminator

Communication satellite systems for Alaska

Technical and cost factors for implementation of Alaskan communication satellite syste

Gamma-Ray Bursts in Circumstellar Shells: A Possible Explanation for Flares

It is now generally accepted that long-duration gamma ray bursts (GRBs) are due to the collapse of massive rotating stars. The precise collapse process itself, however, is not yet fully understood. Strong winds, outbursts, and intense ionizing UV radiation from single stars or strongly interacting binaries are expected to destroy the molecular cloud cores that give birth to them and create highly complex circumburst environments for the explosion. Such environments might imprint features on GRB light curves that uniquely identify the nature of the progenitor and its collapse. We have performed numerical simulations of realistic environments for a variety of long-duration GRB progenitors with ZEUS-MP, and have developed an analytical method for calculating GRB light curves in these profiles. Though a full, three-dimensional, relativistic magnetohydrodynamical computational model is required to precisely describe the light curve from a GRB in complex environments, our method can provide a qualitative understanding of these phenomena. We find that, in the context of the standard afterglow model, massive shells around GRBs produce strong signatures in their light curves, and that this can distinguish them from those occurring in uniform media or steady winds. These features can constrain the mass of the shell and the properties of the wind before and after the ejection. Moreover, the interaction of the GRB with the circumburst shell is seen to produce features that are consistent with observed X-ray flares that are often attributed to delayed energy injection by the central engine. Our algorithm for computing light curves is also applicable to GRBs in a variety of environments such as those in high-redshift cosmological halos or protogalaxies, both of which will soon be targets of future surveys such as JANUS or Lobster.Comment: 12 pages, 5 figures, Accepted by Ap

Radiation Hydrodynamical Instabilities in Cosmological and Galactic Ionization Fronts

Ionization fronts, the sharp radiation fronts behind which H/He ionizing photons from massive stars and galaxies propagate through space, were ubiquitous in the universe from its earliest times. The cosmic dark ages ended with the formation of the first primeval stars and galaxies a few hundred Myr after the Big Bang. Numerical simulations suggest that stars in this era were very massive, 25 - 500 solar masses, with H II regions of up to 30,000 light-years in diameter. We present three-dimensional radiation hydrodynamical calculations that reveal that the I-fronts of the first stars and galaxies were prone to violent instabilities, enhancing the escape of UV photons into the early intergalactic medium (IGM) and forming clumpy media in which supernovae later exploded. The enrichment of such clumps with metals by the first supernovae may have led to the prompt formation of a second generation of low-mass stars, profoundly transforming the nature of the first protogalaxies. Cosmological radiation hydrodynamics is unique because ionizing photons coupled strongly to both gas flows and primordial chemistry at early epochs, introducing a hierarchy of disparate characteristic timescales whose relative magnitudes can vary greatly throughout a given calculation. We describe the adaptive multistep integration scheme we have developed for the self-consistent transport of both cosmological and galactic ionization fronts.Comment: 6 pages, 4 figures, accepted for proceedings of HEDLA2010, Caltech, March 15 - 18, 201

Selection of a new computer system for Executive Director, Inc.

Executive Director, Inc. (EDI), an association management firm, wants to replace its existing computer system. The new computer system should be able to accommodate all of the database and processing requirements of EDI\u27s eight clients. The three areas of consideration when purchasing this new computer system include the software capabilities, the hardware configuration and vendor support

Basal Food Web Dynamics in a Natural Eelgrass (Zostera marina) Community: Cage-Free Field Experimentation

The relative strength of bottom-up and top-down processes operating within food webs is a fundamental determinant of community structure and function. In marine systems, inconspicuous but often highly abundant invertebrate herbivores (mesograzers) are implicated as strong consumers of primary production and important prey for higher-order consumers. Because of their small size, however, mesograzer abundance is not easily manipulated in the field, which limits our ability to adequately assess their grazing impacts. Seagrass systems present a pressing need for the study of food web dynamics because anthropogenic nutrient and sediment inputs decrease the amount of light reaching seagrass leaves, which limits the depth distribution of seagrasses via reduced photosynthesis to respiration ratios. Mesograzers benefit seagrass through their consumption of epiphytic algae and thus may mitigate the loss of seagrass beds due to nutrient enrichment. I test the relative impacts of nutrient enrichment and crustacean mesograzer abundance on epiphytes in a natural seagrass bed without using cages. My work presents the first cage-free tests of crustacean mesograzing impacts in natural seagrass communities. I successfully decreased crustacean abundance for extended periods of time in multiple experiments using a degradable chemical deterrent. Crustacean mesograzer reduction led to concomitant increases in epiphytic algal biomass, while nutrients increased epiphytes only in the absence of mesograzers. My results validate early work from mesocosm and field cage studies designed to test grazing impacts of mesograzers and support the hypothesis that mesograzers indirectly benefit seagrass through a positive indirect interaction

Whey-Caseinate Blends and Lactose Hydrolysis in Yogurt Manufacture

Yogurt is a highly nutritious cultured dairy product which has been consumed for centuries, particularly in Eastern Europe. Although per capita consumption in the United. States is still far below that of most European countries; yogurt sales in the U.S.A. have increased phenomenally during the past three decades. Yogurt sales in the U.S.A. totaled 7.7 million kg in 1955; 31.8 million kg in 1966; and approximately 227 million kg by 1976 (41). Per capita sales increased 211% from 1970 to 1980 (45). Yogurt is generally manufactured from milk or lowfat milk which has been fortified with extra milk solids. Nonfat dry milk (NDM) is the usual source of these milk solids, but NDM has been steadily increasing in price. The price of NDM has increased from $1.76/kg in 1979 (14) to$2.11/kg in 1982 (15), an increase of 20%. Less expensive but compositionally and nutritionally equivalent substitutes for NDM in the manufacture of yogurt, such as certain modified whey products, would seem to present an economically attractive alternative to the yogurt processor. The Whey Products Institute estimates approximately 18.2 million kg of whey were produced in the U.S.A. in 1980, of which less than half was processed and used in human foods (4). About 55% of the processed whey was concentrated and spray dried into a variety of products. Greater usage of these products in human foodstuffs has become possible because of greatly improved product quality attributed to better sanitation, handling, and processing methods. Many nutritious whey products, such as partially delactosed or demineralized whey powders and whey protein concentrates (WPC) with the proteins in an undenatured form, are available to the dairy processor. Depending upon the processing methods, the whey protein products possess a wide range of function.al and nutritional properties which make possible variety of applications in food products (16). A major component of the milk solids in yogurt is the disaccharide, lactose. Lactase enzyme hydrolyzes lactose into glucose and galactose which individually and together are sweeter than lactose itself. The resulting sugar mixture is also more soluble (31), easily digestible by lactose intolerant individuals, and is more readily fermented by lactic acid organisms (52). In general, northern Europeans and their descendants and members of two African tribes are the only persons who retain their childhood ability to digest lactose as adults. An estimated 30 million Americans can not digest lactose properly and among certain ethnic groups (Blacks, Asians, Mediterraneans, Jews, Southern and Central Europeans, and American Indians), 70% have difficulty digesting lactose as adults (9). Hydrolysis of at least part of the lactose in milk prior ~o its manufacture into various products not only may be a potential partial solution to the lactose intolerance problem (31), but it may result in improved products with increased sweetness without increased calories (17, 31), increased carbohydrate solubility, and better mouth feel and body (3, 31). One objective of this research was to determine the feasibility of using two reconstructed milk products (RMP) as economical replacements for NDM in fortifying 2% lowfat milk for yogurt. These RMP\u27s were spray dried blends_ of _whey proteins and caseinates. A second objective was to determine if concomitantly, partial enzymatic hydrolysis of lactose would afford the · same degree of sweetness in yogurts containing less sucrose than nonhydrolyzed yogurts. A yogurt with less sucrose should be attractive to consumers seeking products with fewer calories and one with lowered lactose levels would be more desirable to those deficient in lactase. Yogurts were manufactured with several concentrations of these variable factors and analyzed for composition. The yogurts were evaluated for flavor by a panel of dairy science faculty and by randomly selected volunteers in a consumer panel

Lands and Forests: Maine and the Nation - A Select Bibliography

Lands and Forests: Maine and the Nation - A Select Bibliography by Margaret A. Whalen, Maine State Archives Published Under Appropriation 04065.1 Researchers Guide to Published Sources (1980?) Contents: General References / New England References / Maine References / Excerpts and Periodical Referenceshttps://digitalcommons.usm.maine.edu/me_collection/1090/thumbnail.jp

Detectability of the First Cosmic Explosions

We present a fully self-consistent simulation of a synthetic survey of the furthermost cosmic explosions. The appearance of the first generation of stars (Population III) in the Universe represents a critical point during cosmic evolution, signaling the end of the dark ages, a period of absence of light sources. Despite their importance, there is no confirmed detection of Population III stars so far. A fraction of these primordial stars are expected to die as pair-instability supernovae (PISNe), and should be bright enough to be observed up to a few hundred million years after the big bang. While the quest for Population III stars continues, detailed theoretical models and computer simulations serve as a testbed for their observability. With the upcoming near-infrared missions, estimates of the feasibility of detecting PISNe are not only timely but imperative. To address this problem, we combine state-of-the-art cosmological and radiative simulations into a complete and self-consistent framework, which includes detailed features of the observational process. We show that a dedicated observational strategy using $\lesssim 8$ per cent of total allocation time of the James Webb Space Telescope mission can provide us up to $\sim 9-15$ detectable PISNe per year.Comment: 9 pages, 8 figures. Minor corrections added to match published versio