1,421 research outputs found

    Nuclear magnetic resonance structural studies of allergen protein

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1994.Includes bibliographical references.by Gregory L. Warren.Ph.D

    Australian higher education institutions transforming the future of teaching and learning through 3d virtual worlds

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    What are educators motivations for using virtual worlds with their students? Are they using them to support the teaching of professions and if this is the case, do they introduce virtual worlds into the curriculum to develop and/or expand students' professional learning networks? Are they using virtual worlds to transform their teaching and learning? In recognition of the exciting opportunities that virtual worlds present for higher education, the DEHub Virtual Worlds Working Group was formed. It is made up of Australian university academics who are investigating the role that virtual worlds will play in the future of education and actively implementing the technology within their own teaching practice and curricula. This paper presents a typology for teaching and learning in 3D virtual worlds and applies the typology to a series of case studies based on the ways in which academics and their institutions are exploiting the power of virtual worlds for diverse purposes ranging from business scenarios and virtual excursions to role-play, experimentation and language development. The case studies offer insight into the ways in which institutions are transforming their teaching for an unknown future through innovative teaching and learning in virtual worlds. The paper demonstrates how virtual worlds enable low cost alternatives to existing pedagogies as well as creating opportunities for rich, immersive and authentic activities that would otherwise not be feasible or maybe not even be possible. Through the use of virtual worlds, teaching and learning can be transformed to cater for an unknown future. © 2010 Sue Gregory, Mark J.W. Lee, Allan Ellis, Brent Gregory, Denise Wood, Mathew Hillier, Matthew Campbell, Jenny Grenfell, Steven Pace, Helen Farley, Angela Thomas, Andrew Cram, Suku Sinnappan, Kerrie Smith, Lyn Hay, Shannon Kennedy-Clark, Ian Warren, Scott Grant, David Craven, Heinz Dreher, Carol Matthews, Deborah Murdoch & Lindy McKeown. © 2010 Sue Gregory, Mark J.W. Lee, Allan Ellis, Brent Gregory, Denise Wood, Mathew Hillier, Matthew Campbell, Jenny Grenfell, Steven Pace, Helen Farley, Angela Thomas, Andrew Cram, Suku Sinnappan, Kerrie Smith, Lyn Hay, Shannon Kennedy-Clark, Ian Warren, Scott Grant, David Craven, Heinz Dreher, Carol Matthews, Deborah Murdoch & Lindy McKeown

    Halo globular clusters observed with AAOmega: dark matter content, metallicity and tidal heating

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    Globular clusters have proven to be essential to our understanding of many important astrophysical phenomena. Here we analyse spectroscopic observations of ten Halo globular clusters to determine their dark matter content, their tidal heating by the Galactic disc and halo, describe their metallicities and the likelihood that Newtonian dynamics explain their kinematics. We analyse a large number of members in all clusters, allowing us to address all these issues together, and we have included NGC 288 and M30 to overlap with previous studies. We find that any flattening of the velocity dispersion profiles in the outer regions of our clusters can be explained by tidal heating. We also find that all our GCs have M/L_V < 5, therefore, we infer the observed dynamics do not require dark matter, or a modification of gravity. We suggest that the lack of tidal heating signatures in distant clusters indicates the Halo is not triaxial. The isothermal rotations of each cluster are measured, with M4 and NGC 288 exhibiting rotation at a level of 0.9 +/- 0.1 km/s and 0.25 +/- 0.15 km/s, respectively. We also indirectly measure the tidal radius of NGC 6752, determining a more realistic figure for this cluster than current literature values. Lastly, an unresolved and intriguing puzzle is uncovered with regard to the cooling of the outer regions of all ten clusters.Comment: 12 pages, 8 figures, 1 table. Accepted for publication in MNRAS

    Concurrent invasions of European starlings in Australia and North America reveal population-specific differentiation in shared genomic regions.

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    A species' success during the invasion of new areas hinges on an interplay between the demographic processes common to invasions and the specific ecological context of the novel environment. Evolutionary genetic studies of invasive species can investigate how genetic bottlenecks and ecological conditions shape genetic variation in invasions, and our study pairs two invasive populations that are hypothesized to be from the same source population to compare how each population evolved during and after introduction. Invasive European starlings (Sturnus vulgaris) established populations in both Australia and North America in the 19th century. Here, we compare whole-genome sequences among native and independently introduced European starling populations to determine how demographic processes interact with rapid evolution to generate similar genetic patterns in these recent and replicated invasions. Demographic models indicate that both invasive populations experienced genetic bottlenecks as expected based on invasion history, and we find that specific genomic regions have differentiated even on this short evolutionary timescale. Despite genetic bottlenecks, we suggest that genetic drift alone cannot explain differentiation in at least two of these regions. The demographic boom intrinsic to many invasions as well as potential inversions may have led to high population-specific differentiation, although the patterns of genetic variation are also consistent with the hypothesis that this infamous and highly mobile invader adapted to novel selection (e.g., extrinsic factors). We use targeted sampling of replicated invasions to identify and evaluate support for multiple, interacting evolutionary mechanisms that lead to differentiation during the invasion process

    UBVRI Light Curves of 44 Type Ia Supernovae

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    We present UBVRI photometry of 44 type-Ia supernovae (SN Ia) observed from 1997 to 2001 as part of a continuing monitoring campaign at the Fred Lawrence Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics. The data set comprises 2190 observations and is the largest homogeneously observed and reduced sample of SN Ia to date, nearly doubling the number of well-observed, nearby SN Ia with published multicolor CCD light curves. The large sample of U-band photometry is a unique addition, with important connections to SN Ia observed at high redshift. The decline rate of SN Ia U-band light curves correlates well with the decline rate in other bands, as does the U-B color at maximum light. However, the U-band peak magnitudes show an increased dispersion relative to other bands even after accounting for extinction and decline rate, amounting to an additional ~40% intrinsic scatter compared to B-band.Comment: 84 authors, 71 pages, 51 tables, 10 figures. Accepted for publication in the Astronomical Journal. Version with high-res figures and electronic data at http://astron.berkeley.edu/~saurabh/cfa2snIa

    Virtual worlds in Australian and New Zealand higher education: Remembering the past, Understanding the present and imagining the future

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    3D virtual reality, including the current generation of multi-user virtual worlds, has had a long history of use in education and training, and it experienced a surge of renewed interest with the advent of Second Life in 2003. What followed shortly after were several years marked by considerable hype around the use of virtual worlds for teaching, learning and research in higher education. For the moment, uptake of the technology seems to have plateaued, with academics either maintaining the status quo and continuing to use virtual worlds as they have previously done or choosing to opt out altogether. This paper presents a brief review of the use of virtual worlds in the Australian and New Zealand higher education sector in the past and reports on its use in the sector at the present time, based on input from members of the Australian and New Zealand Virtual Worlds Working Group. It then adopts a forward-looking perspective amid the current climate of uncertainty, musing on future directions and offering suggestions for potential new applications in light of recent technological developments and innovations in the area

    A High-Resolution Map of Human Evolutionary Constraint Using 29 Mammals

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    The comparison of related genomes has emerged as a powerful lens for genome interpretation. Here we report the sequencing and comparative analysis of 29 eutherian genomes. We confirm that at least 5.5% of the human genome has undergone purifying selection, and locate constrained elements covering ~4.2% of the genome. We use evolutionary signatures and comparisons with experimental data sets to suggest candidate functions for ~60% of constrained bases. These elements reveal a small number of new coding exons, candidate stop codon readthrough events and over 10,000 regions of overlapping synonymous constraint within protein-coding exons. We find 220 candidate RNA structural families, and nearly a million elements overlapping potential promoter, enhancer and insulator regions. We report specific amino acid residues that have undergone positive selection, 280,000 non-coding elements exapted from mobile elements and more than 1,000 primate- and human-accelerated elements. Overlap with disease-associated variants indicates that our findings will be relevant for studies of human biology, health and disease.National Human Genome Research Institute (U.S.)National Institute of General Medical Sciences (U.S.) (Grant number GM82901)National Science Foundation (U.S.). Postdoctural Fellowship (Award 0905968)National Science Foundation (U.S.). Career (0644282)National Institutes of Health (U.S.) (R01-HG004037)Alfred P. Sloan Foundation.Austrian Science Fund. Erwin Schrodinger Fellowshi
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