6,822 research outputs found
Global late Quaternary megafauna extinctions linked to humans, not climate change
The late Quaternary megafauna extinction was a severe global-scale event. Two factors, climate change and modern humans, have received broad support as the primary drivers, but their absolute and relative importance remains controversial. To date, focus has been on the extinction chronology of individual or small groups of species, specific geographical regions or macroscale studies at very coarse geographical and taxonomic resolution, limiting the possibility of adequately testing the proposed hypotheses. We present, to our knowledge, the first global analysis of this extinction based on comprehensive country-level data on the geographical distribution of all large mammal species (more than or equal to 10 kg) that have gone globally or continentally extinct between the beginning of the Last Interglacial at 132 000 years BP and the late Holocene 1000 years BP, testing the relative roles played by glacial–interglacial climate change and humans. We show that the severity of extinction is strongly tied to hominin palaeobiogeography, with at most a weak, Eurasia-specific link to climate change. This first species-level macroscale analysis at relatively high geographical resolution provides strong support for modern humans as the primary driver of the worldwide megafauna losses during the late Quaternary
D=3, N=8 conformal supergravity and the Dragon window
We give a superspace description of D=3, N=8 supergravity. The formulation is
off-shell in the sense that the equations of motion are not implied by the
superspace constraints (but an action principle is not given). The multiplet
structure is unconventional, which we connect to the existence of a "Dragon
window", that is modules occurring in the supercurvature but not in the
supertorsion. According to Dragon's theorem this cannot happen above three
dimensions. We clarify the relevance of this window for going on the conformal
shell, and discuss some aspects of coupling to conformal matter.Comment: plain tex, 24 pp v2: minor change
Temporal inabilities and decision-making capacity in depression
We report on an interview-based study of decision-making capacity in two classes of patients suffering from depression. Developing a method of second-person hermeneutic phenomenology, we articulate the distinctive combination of temporal agility and temporal inability characteristic of the experience of severely depressed patients. We argue that a cluster of decision-specific temporal abilities is a critical element of decision-making capacity, and we show that loss of these abilities is a risk factor distinguishing severely depressed patients from mildly/moderately depressed patients. We explore the legal and clinical consequences of this result
Towards a manifestly supersymmetric action for 11-dimensional supergravity
We investigate the possibility of writing a manifestly supersymmetric action
for 11-dimensional supergravity. The construction involves an explicit relation
between the fields in the super-vielbein and the super-3-form, and uses
non-minimal pure spinors. A simple cubic interaction term for a single scalar
superfield is found.Comment: 22 pp., plain tex. v2: references adde
Recommended from our members
Sporormiella as a tool for detecting the presence of large herbivores in the Neotropics
The reliability of using the abundance of Sporormiella spores as a proxy for the presence and abundance of megaherbivores was tested in southern Brazil. Mud-water interface samples from nine lakes, in which cattle-use was categorized as high, medium, or low, were assayed for Sporormiella representation. The sampling design allowed an analysis of both the influence of the number of animals using the shoreline and the distance of the sampling site from the nearest shoreline. Sporormiella was found to be a reliable proxy for the presence of large livestock. The concentration and abundance of spores declined from the edge of the lake toward the center, with the strongest response being in sites with high livestock use. Consistent with prior studies in temperate regions, we find that Sporormiella spores are a useful proxy to study the extinction of Pleistocene megafauna or the arrival of European livestock in Neotropical landscapes
Spin selective filtering of polariton condensate flow
Spin-selective spatial filtering of propagating polariton condensates, using a controllable spin-dependent gating barrier, in a one-dimensional semiconductor microcavity ridge waveguide is reported. A nonresonant laser beam provides the source of propagating polaritons, while a second circularly polarized weak beam imprints a spin dependent potential barrier, which gates the polariton flow and generates polariton spin currents. A complete spin-based control over the blocked and transmitted polaritons is obtained by varying the gate polarization
Welcome to Implementation Science
Implementation research is the scientific study of methods to promote the systematic uptake of research findings and other evidence-based practices into routine practice, and, hence, to improve the quality and effectiveness of health services and care. This relatively new field includes the study of influences on healthcare professional and organisational behaviour. Implementation Science will encompass all aspects of research in this field, in clinical, community and policy contexts. This online journal will provide a unique platform for this type of research and will publish a broad range of articles – study protocols, debate, theoretical and conceptual articles, rigorous evaluations of the process of change, and articles on methodology and rigorously developed tools – that will enhance the development and refinement of implementation research. No one discipline, research design, or paradigm will be favoured. Implementation Science looks forward to receiving manuscripts that facilitate the continued development of the field, and contribute to healthcare policy and practice
Dynamics of a polariton condensate transistor switch
We present a time-resolved study of the logical operation of a polariton condensate transistor switch.
Creating a polariton condensate (source) in a GaAs ridge-shaped microcavity with a non-resonant pulsed laser beam, the polariton propagation towards a collector, at the ridge edge, is controlled by a
second weak pulse (gate), located between the source and the collector. The experimental results are
interpreted in the light of simulations based on the generalized Gross-Pitaevskii equation, including
incoherent pumping, decay, and energy relaxation within the condensate
Measurement of blood pressure in the leg - a statement on behalf of the British and Irish Hypertension Society
This is the final version. Available on open access from Springer Nature via the DOI in this recordAnkle blood pressure (BP) measurement is necessary for the diagnosis of hypertension where measurements are not possible due to medical conditions or limb deformities. Based on a recent review of the evidence, we recommend an ankle BP threshold of ≥155/90 mmHg to define high blood pressure in patients who do not have vascular disease. We recommend that ankle BP readings are taken with the subject lying down, using a validated automated device with the cuff placed around the ankle/lower calf.Wellcome TrustRoyal SocietyNational Institute for Health Research (NIHR
- …