759 research outputs found
Progressive Metamorphism of Pelitic, Carbonate, and Basic Rocks in South-Central Connecticut
Guidebook for field trips in Connecticut: New England Intercollegiate Geological Conference 60th annual meeting, Yale University, New Haven, Connecticut, October 25-27, 1968: Trip D-
Multiband Superconductivity in KFe2As2: Evidence for one Isotropic and several Liliputian Energy Gaps
We report a detailed low-temperature thermodynamic investigation (heat
capacity and magnetization) of the superconducting state of KFe2As2 for H || c
axis. Our measurements reveal that the properties of KFe2As2 are dominated by a
relatively large nodeless energy gap (Delta?0 = 1.9 kBTc) which excludes dx2-y2
symmetry. We prove the existence of several additional extremely small gaps
(?Delta0 < 1.0 kBTc) that have a profound impact on the low-temperature and
low-field behavior, similar to MgB2, CeCoIn5 and PrOs4Sb12. The zero-field heat
capacity is analyzed in a realistic self-consistent 4-band BCS model which
qualitatively reproduces the recent laser ARPES results of Okazaki et al.
(Science 337 (2012) 1314). Our results show that extremely low-temperature
measurements, i.e. T < 0.1 K, will be required in order to resolve the question
of the existence of line nodes in this compound.Comment: 7 pages, 6 figure
Diagnostic single nucleotide polymorphism markers to identify hybridization between dromedary and Bactrian camels
This article sets out findings from a small-scale collaborative project evaluating the use of a self-audit tool to promote the development of information literacy in MA social work students at a university in the north of England. The project involved the use of the audit tool early in the first and second years of a two-year professional masters programme and, alongside this, completion of two evaluation questionnaires. Analysis of the data suggested substantially increased confidence(measured by self-report) in the identified skills over the first year of the programme. The authors recognise that many factors may contribute to improved confidence and skills. Nevertheless, students identified use of the tool and the signposting to resources within it as helpful, and most felt that the stated aims had been met
A Constraint-based model of Dynamic Island Biogeography: environmental history and species traits predict hysteresis in populations and communities
A Constraint-based model of Dynamic Island Biogeography: environmental history and species traits predict hysteresis in populations and communities We present a conceptual model that shows how hysteresis can emerge in dynamic island systems given simple constraints on trait-mediated processes. Over time, many islands cycle between phases of increasing and decreasing size and connectivity to a mainland species pool. As these phases alternate, the dominant process driving species composition switches between colonization and extinction. Both processes are mediated by interactions between organismal traits and environmental constraints: colonization probability is affected by a species’ ability to cross the intervening matrix between a population source and the island; population persistence (or extinction) is driven by the minimum spatial requirements for sustaining an isolated population. Because different suites of traits often mediate these two processes, similar environmental conditions can lead to differences in species compositions at two points of time. Thus, the Constraint-based model of Dynamic Island Biogeography (C-DIB) illustrates the possible role of hysteresis—the dependency of outcomes not only on the current system state but also the system’s history of environmental change—in affecting populations and communities in insular systems. The model provides a framework upon which additional considerations of lag times, biotic interactions, evolution, and other processes can be incorporated. Importantly, it provides a testable framework to study the physical and biological constraints on populations and communities across diverse taxa, scales, and systems
Advances in the Geology of the Tobacco Root Mountains, Montana, and Their Implications for the History of the Northern Wyoming Province
Integrated studies by Keck Geology Consortium participants have generated many new insights into the Precambrian geology of the Tobacco Root Mountains. We have clarified the tectonic setting and origin of two suites of metamorphic rocks: (1) a quartzofeldspathic gneiss complex with associated metasupracrustal rocks (the combined Indian Creek and Pony–Middle Mountain Metamorphic Suites) that originated in a continental arc setting between 3.35 and 3.2 Ga with subsequent sedimentation and (2) mafic metavolcanic rocks with intercalated metasedimentary rocks (the Spuhler Peak Metamorphic Suite) from a suprasubduction zone ophiolite or backarc basin possibly of Proterozoic age. A poorly preserved metamorphic event at 2.45 Ga affected the former but not the latter, as did the intrusion of rift-related mafic dikes and sills at 2.06 Ga. Both suites were amalgamated, metamorphosed to at least upper amphibolite facies, subjected to simple shear strain and folded into map- and outcrop-scale sheath folds, and tectonically unroofed during the period 1.78 to 1.71 Ga. We name this event the Big Sky orogeny.
The Proterozoic geology of the Tobacco Root Mountains can be integrated with coeval features of the geology of the northern Wyoming province to outline a northeast-trending, southeast-vergent belt as the Big Sky orogen. The Big Sky orogen consists of a metamorphic hinterland flanked to the southeast by a foreland of discrete ductile shear zones cutting older basement, and to the northwest by arc-related metaplutonic bodies and the trace of a fossil subduction zone in the upper mantle. Archean blocks to the north of the Big Sky orogen may have been accreted as allochthonous terranes during collision and convergence.
The remarkable synchroneity of collision along the Big Sky orogen with tectonism in the Trans-Hudson orogen along the eastern margin of the Wyoming province and in the Cheyenne belt to the south of the province raise profound but unanswered questions about the process by which the Wyoming province was added to the rest of the ancestral North American craton
Developing a clinical prediction rule for repeated consultations with functional somatic symptoms in primary care:A cohort study
OBJECTIVES: Patients who present in primary care with chronic functional somatic symptoms (FSS) have reduced quality of life and increased health care costs. Recognising these early is a challenge. The aim is to develop and internally validate a clinical prediction rule for repeated consultations with FSS. DESIGN AND SETTING: Records from the longitudinal population-based ('Lifelines') cohort study were linked to electronic health records from general practitioners (GPs). PARTICIPANTS: We included patients consulting a GP with FSS within 1 year after baseline assessment in the Lifelines cohort. OUTCOME MEASURES: The outcome is repeated consultations with FSS, defined as ≥3 extra consultations for FSS within 1 year after the first consultation. Multivariable logistic regression, with bootstrapping for internal validation, was used to develop a risk prediction model from 14 literature-based predictors. Model discrimination, calibration and diagnostic accuracy were assessed. RESULTS: 18 810 participants were identified by database linkage, of whom 2650 consulted a GP with FSS and 297 (11%) had ≥3 extra consultations. In the final multivariable model, older age, female sex, lack of healthy activity, presence of generalised anxiety disorder and higher number of GP consultations in the last year predicted repeated consultations. Discrimination after internal validation was 0.64 with a calibration slope of 0.95. The positive predictive value of patients with high scores on the model was 0.37 (0.29-0.47). CONCLUSIONS: Several theoretically suggested predisposing and precipitating predictors, including neuroticism and stressful life events, surprisingly failed to contribute to our final model. Moreover, this model mostly included general predictors of increased risk of repeated consultations among patients with FSS. The model discrimination and positive predictive values were insufficient and preclude clinical implementation
Fast Gibbs sampling for high-dimensional Bayesian inversion
Solving ill-posed inverse problems by Bayesian inference has recently
attracted considerable attention. Compared to deterministic approaches, the
probabilistic representation of the solution by the posterior distribution can
be exploited to explore and quantify its uncertainties. In applications where
the inverse solution is subject to further analysis procedures, this can be a
significant advantage. Alongside theoretical progress, various new
computational techniques allow to sample very high dimensional posterior
distributions: In [Lucka2012], a Markov chain Monte Carlo (MCMC) posterior
sampler was developed for linear inverse problems with -type priors. In
this article, we extend this single component Gibbs-type sampler to a wide
range of priors used in Bayesian inversion, such as general priors
with additional hard constraints. Besides a fast computation of the
conditional, single component densities in an explicit, parameterized form, a
fast, robust and exact sampling from these one-dimensional densities is key to
obtain an efficient algorithm. We demonstrate that a generalization of slice
sampling can utilize their specific structure for this task and illustrate the
performance of the resulting slice-within-Gibbs samplers by different computed
examples. These new samplers allow us to perform sample-based Bayesian
inference in high-dimensional scenarios with certain priors for the first time,
including the inversion of computed tomography (CT) data with the popular
isotropic total variation (TV) prior.Comment: submitted to "Inverse Problems
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