962 research outputs found

    A Virialized Filamentary Infrared Dark Cloud

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    The initial conditions of massive star and star cluster formation are expected to be cold, dense and high column density regions of the interstellar medium, which can reveal themselves via near, mid and even far-infrared absorption as Infrared Dark Clouds (IRDCs). Elucidating the dynamical state of IRDCs thus constrains theoretical models of these complex processes. In particular, it is important to assess whether IRDCs have reached virial equilibrium, where the internal pressure balances that due to the self-gravitating weight of the cloud plus the pressure of the external environmental. We study this question for the filamentary IRDC G035.39-00.33 by deriving mass from combined NIR & MIR extinction maps and velocity dispersion from C18O (1-0) & (2-1) line emission. In contrast to our previous moderately super-virial results based on 13CO emission and MIR-only extinction mapping, with improved mass measurements we now find that the filament is consistent with being in virial equilibrium, at least in its central parsec-wide region where ~1000 M_Sun snakes along several parsecs. This equilibrium state does not require large-scale net support or confinement by magnetic fields.Comment: 4 pages, 2 figures, Accepted to ApJ

    Does retrieval fluency contribute to the underconfidence-withpractice effect

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    Judgments of learning (JOLs) made during multiple study-test trials underestimate increases in recall performance across those trials, an effect that has been dubbed the underconfidence-with-practice (UWP) effect. In 3 experiments, the authors examined the contribution of retrieval fluency to the UWP effect for immediate and delayed JOLs. The UWP effect was demonstrated with reliable underconfidence on Trial 2 occurring for both kinds of JOL. However, in contrast to a retrieval-fluency hypothesis, fine-grained analyses indicated that the reliance of JOLs on retrieval fluency contributed minimally to the UWP effect. Our discussion focuses on the status of the retrieval-fluency hypothesis for the UWP effect

    Magnitude and accuracy differences between judgements of remembering and forgetting

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    Metacognition researchers have recently begun to examine the effects of framing judgements of learning (JOLs) in terms of forgetting (rather than remembering) on the judgements' magnitude and accuracy. Although a promising new direction for the study of metamemory, initial studies have yielded inconsistent results. To help resolve these inconsistencies, in four experiments we had college students (N = 434) study paired associates and make JOLs framed in terms of either remembering or forgetting over two study-test trials. Our goals were to further document the effects of framing on the magnitude and accuracy of JOLs and to consider explanations for why specific patterns tend to emerge. The present experiments provide evidence that (a) judgements of forgetting are psychologically anchored at the midpoint of the JOL scale, whereas judgements of remembering are anchored at a lower point, (b) differences in absolute accuracy (calibration) by frame are largely artefactual and stem from differences in anchoring, (c) differences in JOL magnitude and absolute accuracy by frame do not obtain when memory cues are salient to participants, and (d) a forget frame impairs the relative accuracy (resolution) of JOLs across trials by reducing participants' reliance on cues such as memory for past test performance

    Baseline reef health surveys at Bangka Island (North Sulawesi, Indonesia) reveal new threats

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    Worldwide coral reef decline appears to be accompanied by an increase in the spread of hard coral diseases. However, whether this is the result of increased direct and indirect human disturbances and/or an increase in natural stresses remains poorly understood. The provision of baseline surveys for monitoring coral health status lays the foundations to assess the effects of any such anthropogenic and/or natural effects on reefs. Therefore, the objectives of this present study were to provide a coral health baseline in a poorly studied area, and to investigate possible correlations between coral health and the level of anthropogenic and natural disturbances. During the survey period, we recorded 20 different types of coral diseases and other compromised health statuses. The most abundant were cases of coral bleaching, followed by skeletal deformations caused by pyrgomatid barnacles, damage caused by fish bites, general pigmentation response and galls caused by cryptochirid crabs. Instances of colonies affected by skeletal eroding bands, and sedimentation damage increased in correlation to the level of bio-chemical disturbance and/or proximity to villages. Moreover, galls caused by cryptochirid crabs appeared more abundant at sites affected by blast fishing and close to a newly opened metal mine. Interestingly, in the investigated area the percentage of corals showing signs of ‘common’ diseases such as black band disease, brown band disease, white syndrome and skeletal eroding band disease were relatively low. Nevertheless, the relatively high occurrence of less common signs of compromised coral-related reef health, including the aggressive overgrowth by sponges, deserves further investigation. Although diseases appear relatively low at the current time, this area may be at the tipping point and an increase in activities such as mining may irredeemably compromise reef health.This research was partially funded by Coral Eye, which hosted FF and covered all field expenses. The non-profit organization Reef Check Italia Onlus sustained the cost for open source publication. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    Mapping the Universe: The 2010 Russell Lecture

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    Redshift surveys are a powerful tool of modern cosmology. We discuss two aspects of their power to map the distribution of mass and light in the universe: (1) measuring the mass distribution extending into the infall regions of rich clusters and (2) applying deep redshift surveys to the selection of clusters of galaxies and to the identification of very large structures (Great Walls). We preview the HectoMAP project, a redshift survey with median redshift z = 0.34 covering 50 square degrees to r= 21. We emphasize the importance and power of spectroscopy for exploring and understanding the nature and evolution of structure in the universe.Comment: 19 pages, 5 figures (2 videos available in the on-line journal article

    The OBO Foundry: Coordinated Evolution of Ontologies to Support Biomedical Data Integration

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    The value of any kind of data is greatly enhanced when it exists in a form that allows it to be integrated with other data. One approach to integration is through the annotation of multiple bodies of data using common controlled vocabularies or ‘ontologies’. Unfortunately, the very success of this approach has led to a proliferation of ontologies, which itself creates obstacles to integration. The Open Biomedical Ontologies (OBO) consortium has set in train a strategy to overcome this problem. Existing OBO ontologies, including the Gene Ontology, are undergoing a process of coordinated reform, and new ontologies being created, on the basis of an evolving set of shared principles governing ontology development. The result is an expanding family of ontologies designed to be interoperable, logically well-formed, and to incorporate accurate representations of biological reality. We describe the OBO Foundry initiative, and provide guidelines for those who might wish to become involved in the future

    Neanderthal diets in central and southeastern Mediterranean Iberia

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    During recent decades, Neanderthal diet has been a major research topic in palaeoanthropology. This has been accelerated by the maturation of different techniques, which have produced a plethora of new information. However, this proliferation of data has led to confusing and contradictory results. Furthermore, most of the ecological dietary studies have been carried out on specimens drawn from different time periods and regions, almost exclusively those characterized by cold, open environmental conditions. Subsistence models based on these fragmentary data have been applied to Neanderthals living in a variety of different regions and environments, even though their dietary strategies may have been as variable as regions they inhabited. In this paper we integrate different dietary approaches (studies of the zooarchaeology, stable isotopes and plant remains) from the central and southeastern Mediterranean coast of Iberia in order to develop a broader and more complex picture of Neanderthal diet in different Mediterranean environmental conditions. Our results suggest that there may have been some minor dietary variation due to climatic or environmental differences, but that Neanderthal diet focussed on large terrestrial game, supplemented by plant foods when these were available

    Mapping Large-Scale CO Depletion in a Filamentary Infrared Dark Cloud

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    Infrared Dark Clouds (IRDCs) are cold, high mass surface density and high density structures, likely to be representative of the initial conditions for massive star and star cluster formation. CO emission from IRDCs has the potential to be useful for tracing their dynamics, but may be affected by depleted gas phase abundances due to freeze-out onto dust grains. Here we analyze C18O J=1-0 and J=2-1 emission line data, taken with the IRAM 30m telescope, of the highly filamentary IRDC G035.39.-0033. We derive the excitation temperature as a function of position and velocity, with typical values of ~7K, and thus derive total mass surface densities, Sigma_C18O, assuming standard gas phase abundances and accounting for optical depth in the line, which can reach values of ~1. The mass surface densities reach values of ~0.07 g/cm^2. We compare these results to the mass surface densities derived from mid-infrared (MIR) extinction mapping, Sigma_SMF, by Butler & Tan, which are expected to be insensitive to the dust temperatures in the cloud. With a significance of >10sigma, we find Sigma_C18O/Sigma_SMF decreases by about a factor of 5 as Sigma increases from ~0.02 to ~0.2 g/cm^2, which we interpret as evidence for CO depletion. Several hundred solar masses are being affected, making this one of the most massive clouds in which CO depletion has been observed directly. We present a map of the depletion factor in the filament and discuss implications for the formation of the IRDC.Comment: 9 pages, accepted to ApJ, Mac users: Figure 1 is best viewed with Adobe acroread rather than previe

    Cannabidiol modulates phosphorylated rpS6 signalling in a zebrafish model of tuberous sclerosis complex

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    Tuberous sclerosis complex (TSC) is a rare disease caused by mutations in the TSC1 or TSC2 genes and is characterized by widespread tumour growth, intractable epilepsy, cognitive deficits and autistic behaviour. CBD has been reported to decrease seizures and inhibit tumour cell progression, therefore we sought to determine the influence of CBD on TSC pathology in zebrafish carrying a nonsense mutation in the tsc2 gene. CBD treatment from 6 to 7 days post-fertilization (dpf) induced significant anxiolytic actions without causing sedation. Furthermore, CBD treatment from 3 dpf had no impact on tsc2-/- larvae motility nor their survival. CBD treatment did, however, reduce the number of phosphorylated rpS6 positive cells, and their cross-sectional cell size. This suggests a CBD mediated suppression of mechanistic target of rapamycin (mTOR) activity in the tsc2-/- larval brain. Taken together, these data suggest that CBD selectively modulates levels of phosphorylated rpS6 in the brain and additionally provides an anxiolytic effect. This is pertinent given the alterations in mTOR signalling in experimental models of TSC. Additional work is necessary to identify upstream signal modulation and to further justify the use of CBD as a possible therapeutic strategy to manage TSC
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