A study of twenty male alcoholic patients who have had two or more admissions to the Boston State Hospital

Thesis (M.S.)--Boston University, 1948. This item was digitized by the Internet Archive

Laser Spectroscopy of Wire-Like Molecules

Cavity-enhanced Laser-Induced Fluorescence With the incorporation of a new optic mount and focussing lens a cavity ring-down set-up was altered to collect fluorescence signal from molecules seeded in a molecular beam. Running both the CRDS and fluorescence measurements simultaneously produced a technique with significantly enhanced sensitivity compared to either of the two individual methods. Preliminary analysis with SO2 and a selection of polyaromatic molecules point to the method been best suited for measuring the fluorescence spectra of fast fluorescence lifetime (< 1 ns) molecules and in confined environments i.e. molecular beams. This has been characterised using a known sample and also compared to the CRDS and fluorescence measurements ran as individual techniques. The method was found to increase the sensitivity of the current experimental set-up by two orders of magnitude. This was then applied in the analysis of two new molecular samples to obtain spectra for use in analysing the torsional motions within the molecule. Torsional Motion Analysis of 2,5-bis(phenylethynyl)thiophene Torsional motions in polyphenyls, potential molecular wires, are important in the charge carriage capability of the species. Using a combination of UV-cavity ring-down and fluorescence detection the absorption and photoexcitation spectra of 2,5-bis(phenylethynyl)thiophene were successfully measured. Using a simple cosine potential and simulation program the spectra were reproduced and were found to be close to the values determined in previous research on the two ring system tolane and 1,4-bis(phenylethynyl)benzene

Comparison of methods of full-feeding yearling steers

Packers are demanding finished cattle that grade Good and Choice and meet certain carcass specifications. This requires that more cattle be full-fed. This program can easily be planned by the Southeastern area farmer who is able to make optimum use of pasture and roughage with a limited full-feeding period to meet the packer and consumer demand. With the constantly increasing costs to farmers, efficient methods of feeding must be developed. Part-time farmers and farmers who finish cattle as a secondary source of income need an efficient feeding method that takes less regularity than the hand feeding method. Further, there is a trend in the Southeast toward more use of shelled corn due to picker-sheller combines and low relative cost of trans-portation of shelled corn from the Midwest by barge. Some feed processing plants have been equipped to prepare and deliver mixed feeds to the feeder. This gives the cattle feeder an opportunity to self-feed cattle without becoming involved in processing or handling any feed. In commercial feedlots, labor, feed efficiency, and disease are major factors in determining profit and loss. With improved cow-calf herds for the production of feeder cattle, Tennessee and the Southeast have become a good location for feedlot operations. The feeding experiments described in this thesis were designed to compare the results of finishing yearling steers in dry-lot by two methods of hand f\ill-feeding and two methods of self-feeding

Green space and child weight status : does outcome measurement matter? Evidence from an Australian longitudinal study

Taren Sanders is supported by an Australian Postgraduate Award. Thomas Astell-Burt is supported by a Fellowship with the National Heart Foundation of Australia.Objective. To examine whether neighbourhood green space is beneficially associated with (i) waist circumference (WC) and (ii) waist-to-height ratio (WtHR) across childhood. Methods. Gender-stratified multilevel linear regressions were used to examine associations between green space and objective measures of weight status in the Longitudinal Study of Australian Children, a nationally representative source of data on 4,423 children aged 6 y to 13 y. WC and WtHR were measured objectively. Percentage green space within the local area of residence was calculated. Effect modification by age was explored, adjusting for socioeconomic confounding. Results. Compared to peers with 0-5% green space locally, boys and girls with >40% green space tended to have lower WC (βboys -1.15, 95% CI -2.44, 0.14; βgirls -0.21, 95% CI -1.47, 1.05) and WtHR (βboys -0.82, 95% CI -1.65, 0.01; βgirls -0.32, 95% CI -1.13, 0.49). Associations among boys were contingent upon age (p valuesage green space40% green space at 73.85 cm and 45.75% compared to those with 0-5% green space at 75.18 cm and 46.62%, respectively. Conclusions. Greener neighbourhoods appear beneficial to alternative child weight status measures, particularly among boys.Publisher PDFPeer reviewe

Re-use of polyamide-12 in powder bed fusion and its effect on process-relevant powder characteristics and final part properties

Powder bed fusion (PBF) is an additive manufacturing technique capable of fabricating highly complex, individualised, and lightweight polymer components. However, to maximise the potential of PBF, in terms of both economic efficiency and environmental sustainability, a successful powder re-use strategy is essential. During a build, ageing and degradation processes affect the re-usability of un-sintered powder, so used powder is usually refreshed with virgin material before re-use. This study considers the effectiveness of using a 70:30 refresh ratio in a specific PBF technique: laser sintering (LS). Across a total of seven printing cycles, polyamide-12 (PA-12) powder refreshed with 30 % virgin material after each build, revealed a 4.5 °C increase in melting temperature. There was also a 20 % reduction in particle flowability, which may be related to the presence of fine satellite particles and considerable particle cracking. This deterioration in powder quality resulted in a 5.8 % increase in total part porosity, and an 11 % reduction in the ultimate tensile strength of fabricated parts, over the seven build cycles. A Pearson correlation test indicated that the reduction in powder flowability was the most significant (p-value of 0.005) cause for the loss of part strength; emphasising that the revolution powder analyser could be a useful complimentary technique for determining the quality of used powder within laser sintering. Nonetheless, compared to previous studies which re-used 100 % aged PA-12 powder, without refreshing with any virgin material, the observed reduction in part strength is relatively modest. This suggests that a 70:30 refresh ratio offers a good compromise between maintaining part performance, particularly for non-critical applications, without having to add an unnecessary amount of virgin powder. Therefore, this study reveals the relationship between the deterioration of powder properties and reductions in part strength; yet highlights the benefits of operating with a 70:30 refresh ratio when re-using PA-12 powder across multiple build cycles

Equilibrium operating performance of axial-flow turbojet engines by means of idealized analysis

A method of predicting equilibrium operating performance of turbojet engines has been developed, with the assumption of simple model processes for the components. Results of the analysis are plotted in terms of dimensionless parameters comprising critical engine dimensions and over-all operating variables. This investigation was made of an engine in which the ratio of axial inlet-air velocity to compressor-tip velocity is constant, which approximates turbojet engines with axial-flow compressors. Experimental correlation of the theory with data from several existing axial-flow-type engines was good and showed close correlation between calculated and measured performance

A New Approach to Developing Interactive Software Modules Through Graduate Education

Educational technology has attained significant importance as a mechanism for supporting experiential learning of science concepts. However, the growth of this mechanism is limited by the significant time and technical expertise needed to develop such products, particularly in specialized fields of science. We sought to test whether interactive, educational, online software modules can be developed effectively by students as a curriculum component of an advanced science course. We discuss a set of 15 such modules developed by Harvard University graduate students to demonstrate various concepts related to astronomy and physics. Their successful development of these modules demonstrates that online software tools for education and outreach on specialized topics can be produced while simultaneously fulfilling project-based learning objectives. We describe a set of technologies suitable for module development and present in detail four examples of modules developed by the students. We offer recommendations for incorporating educational software development within a graduate curriculum and conclude by discussing the relevance of this novel approach to new online learning environments like edX.Astronom