Seeded gas thrusters and related system components

A program involved with the construction and test of a number of laser heated thrusters is described. These thrusters, with a cavity approximately 23 cm long and 3.5 cm in i.d., are to be tested by NASA at a later date with a laser beam focused through the throat to heat hydrogen propellant containing an opacifier. The heated propellant exhausts through a supersonic nozzle with a 0.6 cm throat at 3000 C. Thrust stands and control systems were furnished with the thrusters. The report describes radio frequency plasma heated hot and cold flow simulation tests by the contractor

Characteristics of feeding and breeding practices for intensification of smallholder dairy systems in the Kenya highlands

This study aimed at better understanding of the characteristics of feeding and breeding practices smallholder farmers adopt in intensifying their dairy production. Use of hired labour for fodder gathering, growing of fodder crops and purchase of feeds increased with increasing intensification, but Bos taurus breeds did not respond to increasing feeding intensification while Bos indicus cattle responded, calving at earlier age and yielding more milk. Overall, first calving occurred at 32 months, but days open prolonged to 250 days with milk yield of 4 litres per day of calving interval. A principal component analysis extracted six feeding and breeding components, explaining 71.79% of the total variations in feeding and breeding practices for dairy intensification. The six components were labelled: non- intensified feeding and breeding; breeding decisions based-intensification; high external resource based-intensification; moderate resource based-intensification; resource poor based-intensification; and moderate external resource based-intensification. These characteristics points to some `evolutionary process¿ of intensification involving feeding and breeding decisions, depending on the risk-bearing capacity of the household. Intensification enhancing interventions for smallholders need be considered in the context of the household economy. Interventions on feeding and breeding have to be packaged together holistically if intensification is to enhance productivity. A selective intervention on only one of these is associated with low productivity levels, only contributing to sustaining family subsistence livelihood

Algorithms for 3D rigidity analysis and a first order percolation transition

A fast computer algorithm, the pebble game, has been used successfully to study rigidity percolation on 2D elastic networks, as well as on a special class of 3D networks, the bond-bending networks. Application of the pebble game approach to general 3D networks has been hindered by the fact that the underlying mathematical theory is, strictly speaking, invalid in this case. We construct an approximate pebble game algorithm for general 3D networks, as well as a slower but exact algorithm, the relaxation algorithm, that we use for testing the new pebble game. Based on the results of these tests and additional considerations, we argue that in the particular case of randomly diluted central-force networks on BCC and FCC lattices, the pebble game is essentially exact. Using the pebble game, we observe an extremely sharp jump in the largest rigid cluster size in bond-diluted central-force networks in 3D, with the percolating cluster appearing and taking up most of the network after a single bond addition. This strongly suggests a first order rigidity percolation transition, which is in contrast to the second order transitions found previously for the 2D central-force and 3D bond-bending networks. While a first order rigidity transition has been observed for Bethe lattices and networks with ``chemical order'', this is the first time it has been seen for a regular randomly diluted network. In the case of site dilution, the transition is also first order for BCC, but results for FCC suggest a second order transition. Even in bond-diluted lattices, while the transition appears massively first order in the order parameter (the percolating cluster size), it is continuous in the elastic moduli. This, and the apparent non-universality, make this phase transition highly unusual.Comment: 28 pages, 19 figure

Harlem Hospital\u27s Journey to Patient Navigation

This essay discusses the history of 20th century black migration to Harlem, New York and the utilization of Harlem Hospital. This examination is based on New York newspaper articles in the 1920’s. They tell the story, from a journalist’s perspective, of the challenges African Americans experienced in their interactions with Harlem Hospital. The implicit communication of segregation of Harlem Hospital at that time is connected to the development of patient navigation in the 1970’s. The creation of patient navigation will be discussed in the context of historical health disparities that are increasingly manifested today

Harlem Hospital’s Journey to Patient Navigation

This essay discusses the history of 20th century black migration to Harlem, New York and the utilization of Harlem Hospital. This examination is based on New York newspaper articles in the 1920’s. They tell the story, from a journalist’s perspective, of the challenges African Americans experienced in their interactions with Harlem Hospital. The implicit communication of segregation of Harlem Hospital at that time is connected to the development of patient navigation in the 1970’s. The creation of patient navigation will be discussed in the context of historical health disparities that are increasingly manifested today

The Detection and Determination of Drugs and Their Metabolites in Biological Fluids

This thesis is concerned with the detection, identification and estimation of drugs and their metabolites in body fluids. The principal drugs studied were the halogenated drugs chlorbutanol and chloral hydrate. One widely used technique for the detection of chloral hydrate and its metabolite, trichloroacetic acid, is the Fujiwara test. This test was also known to be capable of detecting chlorbutanol. The reaction conditions were studied to determine the optimum conditions for the detection of chlorbutanol. As part of the investigation into the optimum conditions an investigation was carried out into the mechanism of the Fujiwara reaction. Previously this test was thought to detect only a series of halogenated compounds. This investigation showed, however, that this is not correct. A positive reaction can be obtained if the reaction conditions lead to the attachment of an electrophilic group to the nitrogen atom of a pyridine ring if this group, in the presence of base, gives rise to a conjugated system which can give rise to an ionised species. A modification of this test was also used for quantitative estimation of the metabolites of chloral hydrate. For the identification of the drugs in body fluids gas chromatography was found to be the most suitable technique. A number of possible systems were investigated and the most suitable chosen for the routine identification and estimation of these drugs. This technique was preferred to the Fujiwara test for estimations as more than one drug can be readily estimated in the same sample. The Fujiwara test was used to study the excretion of chlorbutanol by racing greyhounds, in conjunction with a comprehensive study designed to assess all aspects of the drug's effects on these animals. A similar study was carried out using phenobarbitone. The gas chromatographic technique was used to investigate the effectiveness of the Fujiwara technique developed, and also a number of aspects relating to the handling of samples thought to contain chlorbutanol. Both the Fujiwara and gas chromatographic techniques were employed in the routine analysis of samples. A study was also carried out into the rapid detection of phenylbutazone and contraceptive steroids. Existing techniques were found to be satisfactory for the detection of phenylbutazone and its metabolites, and these substances were characterised using these techniques. However a simple, speedy technique is not practical for the detection of contraceptive steroids in urine samples. The technique of gas chromatography was also used to identify and estimate a number of volatile materials. This was originally carried out to detect contaminants in the reagents used for the Fujiwara test, but also found an application in a post-mortem analysis. One of the column packings found to be unsuitable for the identification of chlorbutanol was found to be capable of separating a wide range of volatile materials. This range included ethanol and trials were carried out in conjunction with a test of the effect of orally administered fructose upon ethanol metabolism. This column packing was found to be a useful supplement to the standard packing used for the determination of blood and urine ethanol concentrations

Study of high resolution wind measuring systems. phase ii- analysis

Comparative analysis of high resolution wind measuring system

Simulator test to study hot-flow problems related to a gas cooled reactor

An advance study of materials, fuel injection, and hot flow problems related to the gas core nuclear rocket is reported. The first task was to test a previously constructed induction heated plasma GCNR simulator above 300 kW. A number of tests are reported operating in the range of 300 kW at 10,000 cps. A second simulator was designed but not constructed for cold-hot visualization studies using louvered walls. A third task was a paper investigation of practical uranium feed systems, including a detailed discussion of related problems. The last assignment resulted in two designs for plasma nozzle test devices that could be operated at 200 atm on hydrogen

The ecology of algae in relation to river water equality surveillance

The broad objectives of the work were to develop standard methods for the routine biological surveillance of river water quality, using the non-planktonic algae. Studies on sampling methodology indicated that natural substrata should be sampled directly wherever possible, but for routine purposes, only a semi-quantitative approach was found to be feasible. Artificial substrata were considered to be useful for sample collection in deeper waters, and of three different types tested, Polythene strips were selected for further investigation essentially on grounds of practicality. These were tested in the deeper reaches of a wide range of river types and water qualities: 26 pool sites in 14 different rivers were studied over a period of 9 months. At each site, the assemblages developing on 3 strips following a 4, or less commonly, an 3 week immersion period were analysed quantitatively. Where possible, the natural substrata were also sampled semi-quantitatively at each site, and at a nearby riffle. The results of this survey were very fragmentary: many strips failed to yield useful data, and the results were often difficult to interpret, and of limited value for water quality surveillance purposes. In one river, the Churnet, the natural substrata at 14 riffle sites were sampled semi-quantitatively on 14 occasions at intervals of 4 weeks. In this survey, the results were more readily interpreted in relation to water quality, and no special data processing was found to be necessary or helpful. Further studies carried out on the filamentous green alga Cladophora showed that this alga may have some value as a bioaccumulation indicator for metals, and as a bioassay organism for the assessment of the algal growth promoting potential of natural river waters

Self-organization with equilibration: a model for the intermediate phase in rigidity percolation

Recent experimental results for covalent glasses suggest the existence of an intermediate phase attributed to the self-organization of the glass network resulting from the tendency to minimize its internal stress. However, the exact nature of this experimentally measured phase remains unclear. We modify a previously proposed model of self-organization by generating a uniform sampling of stress-free networks. In our model, studied on a diluted triangular lattice, an unusual intermediate phase appears, in which both rigid and floppy networks have a chance to occur, a result also observed in a related model on a Bethe lattice by Barre et al. [Phys. Rev. Lett. 94, 208701 (2005)]. Our results for the bond-configurational entropy of self-organized networks, which turns out to be only about 2% lower than that of random networks, suggest that a self-organized intermediate phase could be common in systems near the rigidity percolation threshold.Comment: 9 pages, 6 figure