370 research outputs found

    Formation of a molecular Bose-Einstein condensate and an entangled atomic gas by Feshbach resonance

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    Processes of association in an atomic Bose-Einstein condensate, and dissociation of the resulting molecular condensate, due to Feshbach resonance in a time-dependent magnetic field, are analyzed incorporating non-mean-field quantum corrections and inelastic collisions. Calculations for the Na atomic condensate demonstrate that there exist optimal conditions under which about 80% of the atomic population can be converted to a relatively long-lived molecular condensate (with lifetimes of 10 ms and more). Entangled atoms in two-mode squeezed states (with noise reduction of about 30 dB) may also be formed by molecular dissociation. A gas of atoms in squeezed or entangled states can have applications in quantum computing, communications, and measurements.Comment: LaTeX, 5 pages with 4 figures, uses REVTeX

    The Kuiper Belt and Other Debris Disks

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    We discuss the current knowledge of the Solar system, focusing on bodies in the outer regions, on the information they provide concerning Solar system formation, and on the possible relationships that may exist between our system and the debris disks of other stars. Beyond the domains of the Terrestrial and giant planets, the comets in the Kuiper belt and the Oort cloud preserve some of our most pristine materials. The Kuiper belt, in particular, is a collisional dust source and a scientific bridge to the dusty "debris disks" observed around many nearby main-sequence stars. Study of the Solar system provides a level of detail that we cannot discern in the distant disks while observations of the disks may help to set the Solar system in proper context.Comment: 50 pages, 25 Figures. To appear in conference proceedings book "Astrophysics in the Next Decade

    Gossip in organisations: Contexts, consequences and controversies

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    This article examines the key themes surrounding gossip including its contexts, the various outcomes (positive and negative) of gossip as well as a selection of challenges and controversies. The challenges which are highlighted revolve around definitional issues, methodological approaches, and ethical considerations. Our analysis suggests that the characteristics and features of gossip lend itself to a process-oriented approach whereby the beginning and, particularly, end points of gossip are not always easily identified. Gossip about a subject or person can temporarily disappear only for it to re-surface at some later stage. In addition, questions pertaining to the effects of gossip and ethical-based arguments depend on the nature of the relationships within the gossip triad (gossiper, listener/respondent and target)

    Demonstration of the effect of stirring on nucleation from experiments on the International Space Station using the ISS-EML facility

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    The effect of fluid flow on crystal nucleation in supercooled liquids is not well understood. The variable density and temperature gradients in the liquid make it difficult to study this under terrestrial gravity conditions. Nucleation experiments were therefore made in a microgravity environment using the Electromagnetic Levitation Facility on the International Space Station on a bulk glass-forming Zr57Cu15.4Ni12.6Al10Nb5 (Vit106), as well as Cu50Zr50 and the quasicrystal-forming Ti39.5Zr39.5Ni21 liquids. The maximum supercooling temperatures for each alloy were measured as a function of controlled stirring by applying various combinations of radio-frequency positioner and heater voltages to the water-cooled copper coils. The flow patterns were simulated from the known parameters for the coil and the levitated samples. The maximum nucleation temperatures increased systematically with increased fluid flow in the liquids for Vit106, but stayed nearly unchanged for the other two. These results are consistent with the predictions from the Coupled-Flux model for nucleation

    A standardisation framework for bio‐logging data to advance ecological research and conservation

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    Bio‐logging data obtained by tagging animals are key to addressing global conservation challenges. However, the many thousands of existing bio‐logging datasets are not easily discoverable, universally comparable, nor readily accessible through existing repositories and across platforms, slowing down ecological research and effective management. A set of universal standards is needed to ensure discoverability, interoperability and effective translation of bio‐logging data into research and management recommendations. We propose a standardisation framework adhering to existing data principles (FAIR: Findable, Accessible, Interoperable and Reusable; and TRUST: Transparency, Responsibility, User focus, Sustainability and Technology) and involving the use of simple templates to create a data flow from manufacturers and researchers to compliant repositories, where automated procedures should be in place to prepare data availability into four standardised levels: (a) decoded raw data, (b) curated data, (c) interpolated data and (d) gridded data. Our framework allows for integration of simple tabular arrays (e.g. csv files) and creation of sharable and interoperable network Common Data Form (netCDF) files containing all the needed information for accuracy‐of‐use, rightful attribution (ensuring data providers keep ownership through the entire process) and data preservation security. We show the standardisation benefits for all stakeholders involved, and illustrate the application of our framework by focusing on marine animals and by providing examples of the workflow across all data levels, including filled templates and code to process data between levels, as well as templates to prepare netCDF files ready for sharing. Adoption of our framework will facilitate collection of Essential Ocean Variables (EOVs) in support of the Global Ocean Observing System (GOOS) and inter‐governmental assessments (e.g. the World Ocean Assessment), and will provide a starting point for broader efforts to establish interoperable bio‐logging data formats across all fields in animal ecology

    Genome-wide association analyses identify 13 new susceptibility loci for generalized vitiligo

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    We previously reported a genome-wide association study (GWAS) identifying 14 susceptibility loci for generalized vitiligo. We report here a second GWAS (450 individuals with vitiligo (cases) and 3,182 controls), an independent replication study (1,440 cases and 1,316 controls) and a meta-analysis (3,187 cases and 6,723 controls) identifying 13 additional vitiligo-associated loci. These include OCA2-HERC2 (combined P = 3.80 × 10 ), MC1R (P = 1.82 × 10 ), a region near TYR (P = 1.57 × 10 ), IFIH1 (P = 4.91 × 10 ), CD80 (P = 3.78 × 10 ), CLNK (P = 1.56 × 10 ), BACH2 (P = 2.53 × 10 ), SLA (P = 1.58 × 10 ), CASP7 (P = 3.56 × 10 ), CD44 (P = 1.78 × 10 ), IKZF4 (P = 2.75 × 10 ), SH2B3 (P = 3.54 × 10 ) and TOB2 (P = 6.81 × 10 ). Most vitiligo susceptibility loci encode immunoregulatory proteins or melanocyte components that likely mediate immune targeting and the relationships among vitiligo, melanoma, and eye, skin and hair coloration

    (Re)framing a philosophical and epistemological framework for teaching and learning in STEM: Emerging pedagogies for complexity

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    Today’s learners are engaging in study where access to knowledge is easier than it ever has been in human history. Rapid advancement of technology and the increasing ease with which communication and interaction can occur has dramatically changed the landscape in which teachers of science, technology, engineering and mathematics (STEM) operate. The contemporary skills that students are required to possess include inter alia problem solving, creativity, teamwork abilities, communication skills and emotional intelligence. Despite the universal acceptance of their importance, these skills are commonly cited as underdeveloped and in addition, are still accompanied by outmoded ‘traditional’ forms of teaching and assessment. While the approaches of twentieth-century education were successful in developing knowledge stores, the ubiquity of access to knowledge—coupled with the constantly changing nature of the world today—requires alternative conceptions of teaching and learning. This article focuses primarily on an exploration of learning metaphors and teaching with the overall lens of creating self-regulated and furthermore, self-determined learners. The article begins with an exploration of learning in STEM education and a critique of the pedagogical perspective, discussing why this epistemology may be insufficient for contemporary STEM learning. The article then considers an alternative and potentially more contemporary notion; the emergent pedagogic space. The article presents a theoretical model to conceptualise learning in STEM education, with the goal of informing both practice and research. The realisation of this proposed emergent pedagogical space is explored through an applied case study from a design and technology context

    Toxoplasma gondii effectors are master regulators of the inflammatory response

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    Toxoplasma is a highly successful parasite that establishes a life-long chronic infection. To do this, it must carefully regulate immune activation and host cell effector mechanisms. Here we review the latest developments in our understanding of how Toxoplasma counteracts the immune response of the host, and in some cases provokes it, through the use of specific parasite effector proteins. An emerging theme from these discoveries is that Toxoplasma effectors are master regulators of the pro-inflammatory response, which elicits many of the toxoplasmacidal mechanisms of the host. We speculate that combinations of these effectors present in certain Toxoplasma strains work to maintain an optimal parasite burden in different hosts to ensure parasite transmission.Knights Templar Eye Foundation, Inc.American Heart Association (0835099N)Massachusetts Life Sciences Center (New Investigator Award)Singapore-MIT Alliance for Research and Technology (SMART)National Institutes of Health (U.S.) (NIH RO1-AI080621)New England Regional Center of Excellence for Biodefense and Emerging Infectious Diseases (NERCE Developmental Grant)National Cancer Institute (U.S.) (Irvington Postdoctoral Fellowship Program
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