Food Preservation by Freezing

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Hydrogen reliquifier Quarterly report, 27 Sept. - 26 Dec. 1967

Computer analyzed hydrogen reliquefier cycles for selection of optimal cycle, rates, and heat exchanger

Who\u27s your expert? Use of an expert opinion survey to inform development of American Psychiatric Association practice guidelines.

OBJECTIVE: For many clinical questions in psychiatry, high-quality evidence is lacking. Credible practice guidelines for such questions depend on transparent, reproducible, and valid methods for assessing expert opinion. The objective of this study was to develop and demonstrate the feasibility of a method for assessing expert opinion to aid in the development of practice guidelines by the American Psychiatric Association (APA). METHODS: A snowball process initially soliciting nominees from three sets of professional leaders was used to identify experts on a guideline topic (psychiatric evaluation). In a Web-based survey, the experts were asked to rate their level of agreement that specific assessments improve specific outcomes when they are included in an initial psychiatric evaluation. The experts were also asked about their own practice patterns with respect to the doing of the assessments. The main outcome measures are the following: number of nominated experts, number of experts who participated in the survey, and number and nature of quantitative and qualitative responses. RESULTS: The snowball process identified 1,738 experts, 784 (45 %) of whom participated in the opinion survey. Participants generally, but not always, agreed or strongly agreed that the assessments asked about would improve specified outcomes. Participants wrote 716 comments explaining why they might not typically include some assessments in an initial evaluation and 1,590 comments concerning other aspects of the topics under consideration. CONCLUSIONS: The snowball process based on initial solicitation of Psychiatry\u27s leaders produced a large expert panel. The Web-based survey systematically assessed the opinions of these experts on the utility of specific psychiatric assessments, providing useful information to substantiate opinion-based practice guidelines on how to conduct a psychiatric evaluation. The considerable engagement of respondents shows promise for using this methodology in developing future APA practice guidelines

Web interfaces to support children's information-seeking activities

Children are making greater and greater use of the Web for educational and entertainment purposes both at school and at home. The past few years have seen the widespread entry of the Internet into schools and classrooms around the world. Since its entrance into the classroom, the Internet has come to be used increasingly as an information resource for class projects. The use of the Internet as an educational resource has spawned interest among researchers from a variety of disciplines (education, library science, human-computer interaction, and so forth) in exploring ways to improve the design of Web sites intended to support children in their information-seeking activities. This research has included: conducting usability studies with children, conducting focus groups with children, and actively involving children as team members in the design of interfaces for Web-based tools intended for their use. This presentation will examine selected Web sites designed specifically to meet the information needs of children, communicate research findings related to the effectiveness of such Web sites, and suggest recommendations for improvements based upon those findings. The Web sites examined will include Yahooligans! and NASA Kids, among others

Species Variation in a Pheromone Complex is Maintained at the Population Level in the Eastern Red-Backed Salamander

Protein pheromones in salamanders of the genus Plethodon have experienced rapid and pervasive directional selection. Variation in mate recognition components, such as the sex-specific pheromones used by plethodontid salamanders, may influence sexual incompatibility and therefore provide a biochemical mechanism for the maintenance of discrete, isolated populations. Recent studies suggest that multiple, genetically distinct lineages of Eastern Red-Backed Salamanders (Plethodon cinereus) are present throughout their broad range. Representative populations from two of these lineages (the Ohio [OH] and Pennsylvania [PA] clades) span the southern shore of Lake Erie in northern Ohio. This distribution pattern creates a unique opportunity to study how phenotypic differences may reinforce population boundaries and possibly lead to speciation. The objectives of this study were to 1) characterize the pheromone profiles of male P. cinereus and 2) determine pheromone variation among populations and between the OH and PA clades. The composition of proteins associated with two known courtship pheromones, Plethodontid Modulating Factor (PMF) and Plethodontid Receptivity Factor (PRF), were compared among eight populations in northern Ohio. Analyses of Similarity (ANOSIM) suggest that both PMF and PRF profiles differ among populations but not between clades. These data suggest that the sex-specific pheromones of P. cinereus in the two clades are not yet different enough to allow reproductive isolation between the two genetic lineages. Although the relative roles of selection and genetic drift are unknown in our populations, specific pheromone isoforms and their effects on mate compatibility should be the focus of future studies aiming to determine mechanisms involved in maintaining population differences

The impact of different teaching approaches and languages on student learning of introductory programming concepts

Many students experience difficulties learning to program. They find learning to program in the object-oriented paradigm particularly challenging. As a result, computing educators have tried a variety of instructional methods to assist beginning programmers. These include developing approaches geared specifically toward novices and experimenting with different introductory programming languages. However, having tried these different methods, computing educators are faced with yet another dilemma: how to tell if any of these interventions actually worked?The research presented here was motivated by an interest in improving practices in computer science education in general and improving my own practices as a computer science educator in particular. Its purpose was to develop an instrument to assess student learning of fundamental and object-oriented programming concepts, and to use that instrument to investigate the impact of different teaching approaches and languages on students’ ability to learn those concepts.Students enrolled in programming courses at two different universities in the Mid-Atlantic region during the 2009-2010 academic year participated in the study. Extensive data analysis showed that the assessment instrument performed well overall. Reliability estimates ranged from 0.65 to 0.79. The instrument is intrinsically valid since the questions are based on the core concepts of the Programming Fundamentals knowledge area defined by the 2008 ACM/IEEE curricular guidelines. Support for content validity includes: 71% of correct responses varied directly with the students’ scores; all possible responses were selected at least once; and 21 out of 24 questions discriminated well between high and low scoring students. CS faculty reviewers indicated that 19 out of 24 questions reflected basic concepts and should be used again “as is” or with “minor changes.” Factor analysis extracted three comprehensible components, “methods and functions,” “mathematical and logical expressions,” and “control structures,” suggesting the instrument is on its way to effectively representing the construct “understanding of fundamental programming concepts.”Statistical analysis revealed significant differences in student performance based on language of instruction. Analyses revealed differences with respect to overall score and questions involving assignment, mathematical and logical expressions, and codecompletion. Language of instruction did not appear to affect student performance on questions addressing object-oriented concepts.Ph.D., Information Science and Technology -- Drexel University, 201

Contribution of G Protein Activation to Fluoride Stimulation of Phosphoinositide Hydrolysis in Human Neuroblastoma Cells

To examine the possibility that NaF enhances phosphoinositide-specific phospholipase C (PIC) activity in neural tissues by a mechanism independent of a guanine nucleotide binding protein (G p ), we have evaluated the contribution of G p activation to NaF-stimulated phosphoinositide hydrolysis in human SK-N-SH neuroblastoma cells. Addition of NaF to intact cells resulted in an increase in the release of inositol phosphates (450% of control values; EC 50 of ∼ 8 m M ). Inclusion of U-73122, an aminosteroid inhibitor of guanine nucleotide-regulated PIC activity in these cells, resulted in a dose-dependent inhibition of NaF-stimulated inositol lipid hydrolysis (IC 50 of ∼ 3.5 Μ M ). When added to digitonin-permeabilized cells, NaF or guanosine-5′- O -thiotriphosphate (GTPΓS) resulted in a three- and sevenfold enhancement, respectively, of inositol phosphate release. In the combined presence of optimal concentrations of NaF and GTPΓS, inositol phosphate release was less than additive, indicative of a common site of action. Inclusion of 2–5 m M concentrations of guanosine-5′- O -(2-thiodiphosphate) (GDPΒS) fully blocked phosphoinositide hydrolysis elicited by GTPΓS, whereas that induced by NaF was partially inhibited (65%). However, preincubation of the cells with GDPΒS resulted in a greater reduction in the ability of NaF to stimulate inositol phosphate release (87% inhibition). Both GTPΓS and NaF-stimulated inositol phosphate release were inhibited by inclusion of 10 Μ M U-73122 (54–71%). The presence of either NaF or GTPΓS also resulted in a marked lowering of the Ca 2+ requirement for activation of PIC in permeabilized cells. These results indicate that in SK-N-SH cells, little evidence exists for direct stimulation of PIC by NaF and that the majority of inositol phosphate release that occurs in the presence of NaF can be attributed to activation of G p .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65259/1/j.1471-4159.1993.tb13406.x.pd

Effect of Storage Time and Temperature on Recovery of \u3ci\u3eSynergistes jonesii\u3c/i\u3e from Rumen Fluid and Feces

Synergistes jonesii is a rumen bacterium that degrades 3,4-dihydroxypyridine (3,4 DHP), the toxic breakdown product of mimosine in leucaena (Leucaena leucocephala). Fecal culture is the most practical way to determine S. jonesii presence in zoological ruminants, particularly if feces can be collected from night penning facilities. Fresh rumen fluid and fecal or fecal slurry (sheep [Ovis spp.] only, 1:4 wt to vol. feces and culture media) from cattle (Bos spp.) and sheep, known to be colonized by S. jonesii, were subjected various storage times (0, 6, 12, and 24 h) and temperatures (5, 23, and 38 oC). Samples were inoculated into a culture medium that contained 3,4 DHP. In general, storage temperature had no affect on detection frequency. Regardless of animal species, detection of S. jonesii was higher (P=0.001) in rumen (97%) than in fecal (40%) samples and level of detection in rumen samples was relatively unaffected by storage time. Detection frequency was similar for both fecal sample types regardless of time (34% fecal vs. 29% fecal slurry). For all fecal samples, detection frequency generally exhibited a linear decline (P=0.01) with time. This study showed that it will be important to collect fresh fecal samples (\u3c 6-h old) from night penning facilities, and because detection levels were low in fecal material, fecal assay would be most accurate on a whole herd rather than an individual animal basis

Stubble Height Effects on Limpograss Pasture Characteristics and Performance of Beef Heifers

Limpograss (Hemarthria altissima [Poir.] Stapf. & C.E. Hubb.) is a C4 species used in Florida beef production systems because of its cool-season growth, persistence on poorly drained soils, and high yield and digestibility. Animal performance on limpograss pastures, however, has been limited by low herbage crude protein (CP). This study evaluated the effect of canopy height of limpograss pastures and N supplementation of grazing cattle on sward characteristics and weight gain and blood urea N (BUN) concentration of yearling beef heifers. Under continuous stocking, six treatments were imposed that included all combinations of three stubble heights (20, 40, and 60 cm) and two N-supplement levels (S, supplemented; NS, unsupplemented). During 1998 and 1999, treatments were replicated twice and arranged in a completely randomized design. Seasonal (84 d) daily gains from heifers grazing limpograss pastures were not different (p= 0.25) between the two years and averaged 522 g. For the intermediate stubble, 40-cm, there was no effect of supplementation on daily gains (P= 0.1), but daily gain increased 40 and 70% due to supplementation (P \u3c 0.01) of heifers on pastures grazed to 20 and 60 cm, respectively. These data show that limpograss stubble height has an impact on pasture nutritive value affecting daily gains. Stubble height of approximately 40 cm seems to provide optimum gains of animals receiving no N supplement on continuously stocked pastures

Improved Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant

The mean life of the positive muon has been measured to a precision of 11 ppm using a low-energy, pulsed muon beam stopped in a ferromagnetic target, which was surrounded by a scintillator detector array. The result, tau_mu = 2.197013(24) us, is in excellent agreement with the previous world average. The new world average tau_mu = 2.197019(21) us determines the Fermi constant G_F = 1.166371(6) x 10^-5 GeV^-2 (5 ppm). Additionally, the precision measurement of the positive muon lifetime is needed to determine the nucleon pseudoscalar coupling g_P.Comment: As published version (PRL, July 2007