11 resultados para Los Alamos Scientific Laboratory. Theoretical Division.

em Deakin Research Online - Australia


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Background and objectives The digestion rate of proteins and subsequent absorption of amino acids can independently modulate protein metabolism. The objective of the present study was to examine the blood amino acid response to whey protein isolate (WPI), β-lactoglobulin-enriched WPI, hydrolysed WPI and a flavour-identical control.

Methods Eight healthy adults (four female, four male) were recruited (mean±standard error of the mean: age, 27.0±0.76 years; body mass index, 23.2±0.8 kg/cm2) and after an overnight fast consumed 500 ml of each drink, each containing 25g protein, in a cross-over design. Blood was taken at rest and then every 15 min for 2 h post ingestion.

Results Ingesting the β-lactoglobulin-enriched WPI drink resulted in significantly greater plasma leucine concentrations at 45-120 min and significantly greater branched-chain amino acid concentrations at 60-105 min post ingestion compared with hydrolysed WPI. No differences were observed between WPI and β-lactoglobulin-enriched WPI, and all protein drinks resulted in elevated blood amino acids compared with flavour-identical control.

Conclusions In conclusion, whole proteins resulted in a more rapid absorption of leucine and branched-chain amino acid into the blood compared with the hydrolysed molecular form of whey protein.

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Small-angle neutron scattering (SANS) analysis and transmission electron microscopy evidence suggest the occurrence of nanoscale porosity in commercial-purity titanium processed by equal-channel angular pressing (ECAP). SANS data were produced at two different facilities (GKSS, Germany; and Los Alamos, USA) and were analysed using three different methods. The results are consistent and yield a conclusive picture of the distribution of the scattering centres, which are believed to be associated with nanoporosity. Back pressure applied during ECAP tends to reduce the average pore size, which also depends on the processing route used. The results of the study strongly suggest that ECAP leaves a footprint in titanium in the form of a population of polydispersed nanovoids, which may play an important role in subsequent processing of the material.

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This article examines the notion of the 'scientist as a moral person' in the light of the early stages of the commodification of science and the transformation of research into a big enterprise, operating on the principle of the division of labour. These processes were set in train at the end of the 19th century. The article focuses on the concomitant changes in the public persona and the habitus of scientific entrepreneurs. I begin by showing the significance of the professional networks that were built up and maintained to further a group's research ideas and the careers of its members, thus demonstrating one condition on which depended their practice of science and their ability to earn a living. This leads to a characterization of the changing styles of work, thought and life, and to a consideration of public perceptions and of the ways in which a new self-image of scholarship and science was fashioned. A critical discussion of the public role of these mandarin scientists follows in order to highlight the strains created by the commodification of science at a time of international tensions and conflicts, when shared beliefs in scholarly cosmopolitanism were subverted by appeals to science and scholarship to work in the service of one's own nation as its 'courtiers'. Various considerations of peculiar analogies between national styles of research and the style of social organization are then noted. In the final section, the article queries the long-term impact of these developments on the ideal of the scientist as a 'moral person'. Taking a cue from Max Weber and pursuing reflections by Zygmunt Bauman on 'science moralized', I argue that the emergence of a type of 'specialists without spirit' was an unintended but fatal consequence of the changes in research practices promoted by scientific entrepreneurs such as Du Bois-Reymond. I conclude that the temptation to sever the ties to a general ethos of civil virtues lay in the rationalization, specialization and potential de-humanization of the objectifying scientific outlook once advocated for its efficiency.

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The memory (and hypnosis) lab at the University of New South Wales investigates a broad range of memory topics. We try to find innovative methods from cognitive and clinical psychology to address theoretical and empirical questions about memory. We aso use hypnosis as one major methodological tool in our investigations of memory (as well as other cognitive processes). In this paper, we review the projects currently underway in our memory (and hypnosis) lab.

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A lack of communication skills is one of the graduate skill deficiencies most commonly cited by employers. Although the writing of laboratory and other scientific reports is a common teaching-and-learning task in university chemistry curricula, this skill is not fully developed in most Australian undergraduate science degrees. Usually, there is no opportunity for practice and feedback before the reports are used for summative assessment. This paper describes a system whereby students are given the opportunity to submit draft reports. After feedback, they can “do it again, thoughtfully”: only the final report is assessed. Student evaluations of the effectiveness of this approach are reported.

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Traditional practical classes in many countries are being rationalised to reduce costs. The challenge for university educators is to provide students with the opportunity to reinforce theoretical concepts by running something other than a traditional practical program. One alternative is to replace wet labs with comparable computer simulations. These virtual experiments involve no harm to animals and require little ongoing expenditure. This study documents second-year physiology students' perceptions of and attitudes to simulations by incorporating several computer simulations into the practical program. Computer simulations met the conceptual and, to some extent, the motivational goals of university practical programs. While students enjoyed both wet labs and computer-simulated exercises, overwhelmingly the wet lab provided the more memorable and stimulating learning experience. Based on this study, students suggested that computer simulations could be effectively used to complement rather than replace practical classes where students gain laboratory skills.

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Larval development of the himri barbel, Barbus luteus Heckel, reared at 19-22 ¡C in natural daylight is described. Morphological and some functional character appearances were similar to the main ontogenetic steps of development in most cyprinids. Small hatched larvae attained both metamorphosis and a length of 10.5 mm after almost 35 days. Relative growth of the selected body proportions demonstrated typical priorities in growth compared to the length. An ontogenetic index was inferred from applying age and length criteria at metamorphosis as a scale for ontogenetic events.

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 An understanding of risks to biodiversity is needed for planning action to slow current rates of decline and secure ecosystem services for future human use. Although the IUCN Red List criteria provide an effective assessment protocol for species, a standard global assessment of risks to higher levels of biodiversity is currently limited. In 2008, IUCN initiated development of risk assessment criteria to support a global Red List of ecosystems. We present a new conceptual model for ecosystem risk assessment founded on a synthesis of relevant ecological theories. To support the model, we review key elements of ecosystem definition and introduce the concept of ecosystem collapse, an analogue of species extinction. The model identifies four distributional and functional symptoms of ecosystem risk as a basis for assessment criteria: a) rates of decline in ecosystem distribution; b) restricted distributions with continuing declines or threats; c) rates of environmental (abiotic) degradation; and d) rates of disruption to biotic processes. A fifth criterion, e) quantitative estimates of the risk of ecosystem collapse, enables integrated assessment of multiple processes and provides a conceptual anchor for the other criteria. We present the theoretical rationale for the construction and interpretation of each criterion. The assessment protocol and threat categories mirror those of the IUCN Red List of species. A trial of the protocol on terrestrial, subterranean, freshwater and marine ecosystems from around the world shows that its concepts are workable and its outcomes are robust, that required data are available, and that results are consistent with assessments carried out by local experts and authorities. The new protocol provides a consistent, practical and theoretically grounded framework for establishing a systematic Red List of the world’s ecosystems. This will complement the Red List of species and strengthen global capacity to report on and monitor the status of biodiversity.

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In this paper we measure the effect of the inflation tax on economic activity and welfare within a controlled setting.To do so,we develop a model of price posting and monetary exchange with inflation and finite populations.The model,which provides a game–theoreticfoundation to Rocheteau and Wright(2005)'s competitive search monetary equilibrium, is used to derive theoretical propositions regarding the effects of inflation in thisenvironment, which we test with a laboratory experiment that closely implements the theoretical framework.We find that the inflation tax is harmful – with cash holdings, production and welfare all falling as inflation rises – and that its effect is relatively larger at low inflation rates than at higher rates.For instance,for inflation rates between 0%and5%, welfare in the two markets we consider (2[seller] 2[buyer] and 3 2) falls by roughly 1 percent for each percentage–point rise in inflation, compared with 0.4 percent over the range from 5% to 30%.Our findings lead us to conclude that the impact of the inflation tax should not be underestimated, even under low inflation.

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The laboratory provides an opportunity for students to achieve many learning outcomes including to critically evaluate information, interpret and draw conclusions from scientific data, and communicate scientific results, information, or arguments. This paper describes a laboratory-writing task that involves self and peer evaluation. After discussion of the expectations of laboratory report writing during class, students self and peer evaluate reports. In a process similar to double-blind journal refereeing, students practise critically evaluating the quality of academic writing using a rubric. The summative assessment is based on how consistent their evaluations are with the evaluations of the same reports performed by their peers. The formative assessment is that students receive peer evaluations and feedback via a rubric on reports that they have written. The skill of critically evaluating their own reports is used to improve the laboratory reports in subsequent assessment tasks.

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Legumes develop root nodules from pluripotent stem cells in the rootpericycle in response to mitogenic activation by a decorated chitin-likenodulation factor synthesized in Rhizobium bacteria. The soybean genes encoding the receptor for such signals were cloned using map-based cloning approaches. Pluripotent cells in the root pericycle and the outer or inner cortex undergo repeated cell divisions to initiate a composite nodule primordium that develops to a functional nitrogen-fixing nodule. The process itself is autoregulated, leading to the characteristic nodulation of the upper root system. Autoregulation of nodulation (AON) in all legumes is controlled in part by a leucine-rich repeat receptor kinase gene (GmNARK). Mutations of GmNARK, and its other legume orthologues, result in abundant nodulation caused by the loss of a yet-undefined negative nodulation repressor system. AON receptor kinases are involved in perception of a long distance, root-derived signal, to negatively control nodule proliferation. GmNARK and LjHAR1 are expressed in phloem parenchyma. GmNARK kinase domain interacts with Kinase Associated Protein Phosphatase (KAPP). NARK gene expression did not mirror biological NARK activity in nodulation control, as q-RT-PCR in soybean revealed high NARK expression in roots, root tips, leaves, petioles, stems and hypocotyls, while shoot and root apical meristems were devoid of NARK RNA. High through-put transcript analysis in soybean leaf and root indicated that major genes involved in JA synthesis or response are preferentially down-regulated in leaf but not root of wild type, but not NARK mutants, suggesting that AON signaling may in part be controlled by events relating to hormone metabolism. Ethylene and abscisic acid insensitive mutants of L. japonicus are described. Nodulation in legumes has significance to global economies and ecologies, as the nitrogen input into the biosphere allows food, feed and biofuel production without the inherent costs associated with nitrogen fertilization [1]. Nodulation involves the production of a new organ capable of nitrogen fixation [2] and as such is an excellent system to study plant – microbe interaction, plant development, long distance signaling and functional genomics of stem cell proliferation [3, 4]. Concerted international effort over the last 20 years, using a combination of induced mutagenesis followed by gene discovery (forward genetics), and molecular/biochemical approaches revealed a complex developmental pathway that ‘loans’ genetic programs from various sources and orchestrates these into a novel contribution. We report our laboratory’s contribution to the present analysis in the field.