2,425 research outputs found

    Adaptive colour change and background choice behaviour in peppered moth caterpillars is mediated by extraocular photoreception

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    Light sensing by tissues distinct from the eye occurs in diverse animal groups, enabling circadian control and phototactic behaviour. Extraocular photoreceptors may also facilitate rapid colour change in cephalopods and lizards, but little is known about the sensory system that mediates slow colour change in arthropods. We previously reported that slow colour change in twig-mimicking caterpillars of the peppered moth (Biston betularia) is a response to achromatic and chromatic visual cues. Here we show that the perception of these cues, and the resulting phenotypic responses, does not require ocular vision. Caterpillars with completely obscured ocelli remained capable of enhancing their crypsis by changing colour and choosing to rest on colour-matching twigs. A suite of visual genes, expressed across the larval integument, likely plays a key role in the mechanism. To our knowledge, this is the first evidence that extraocular colour sensing can mediate pigment-based colour change and behaviour in an arthropod

    A Processor Core Model for Quantum Computing

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    We describe an architecture based on a processing 'core' where multiple qubits interact perpetually, and a separate 'store' where qubits exist in isolation. Computation consists of single qubit operations, swaps between the store and the core, and free evolution of the core. This enables computation using physical systems where the entangling interactions are 'always on'. Alternatively, for switchable systems our model constitutes a prescription for optimizing many-qubit gates. We discuss implementations of the quantum Fourier transform, Hamiltonian simulation, and quantum error correction.Comment: 5 pages, 2 figures; improved some arguments as suggested by a refere

    Collapse of Vacuum Bubbles in a Vacuum

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    Motivated by the discovery of a plenitude of metastable vacua in a string landscape and the possibility of rapid tunneling between these vacua, we revisit the dynamics of a false vacuum bubble in a background de Sitter spacetime. We find that there exists a large parameter space that allows the bubble to collapse into a black hole or to form a wormhole. This may have interesting implications to inflationary physics.Comment: 8 pages including 6 figures, LaTex; references adde

    Exact solution and interfacial tension of the six-vertex model with anti-periodic boundary conditions

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    We consider the six-vertex model with anti-periodic boundary conditions across a finite strip. The row-to-row transfer matrix is diagonalised by the `commuting transfer matrices' method. {}From the exact solution we obtain an independent derivation of the interfacial tension of the six-vertex model in the anti-ferroelectric phase. The nature of the corresponding integrable boundary condition on the XXZXXZ spin chain is also discussed.Comment: 18 pages, LaTeX with 1 PostScript figur

    Mental health treatment: Reaching more kids

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    Background: Nearly 70% of children who are in need of specialized mental health services do not access them. We set out to identify effective self-delivered interventions as a way to help bridge the gap between those in need and those being serviced. Methods: We used systematic review methods to identify randomized control trials (RCTs) evaluating self-delivered treatments. After applying our rigorous inclusion criteria, we accepted five RCTs evaluating five treatment interventions. Results: Three self-directed family interventions reduced anxiety diagnoses and symptoms for school age children. One self-directed parenting intervention reduced ADHD diagnoses for school age children. Additionally, one self-directed youth invention reduced depression symptoms for adolescents. Conclusions: Strong research evidence supports the use of self-directed treatments to address three common childhood mental disorders. Greater use of these interventions can expand the number of children who are reached with effective treatments

    Direct retrieval of stratospheric CO_2 infrared cooling rate profiles from AIRS data

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    We expand upon methods for retrieving thermal infrared cooling rate profiles, originally developed by Liou and Xue (1988) through application to the inversion of the stratospheric cooling rate produced by carbon dioxide (CO_2) and a formal description of the associated error budget. Specifically, we infer lower- and mid-stratospheric cooling rates from the CO_2 ν_2 band on the basis of selected spectral channels and available data from the Atmospheric Infrared Sounder (AIRS). In order to establish the validity of our results, we compare our retrievals to those calculated from a forward radiative transfer program using retrieved temperature data from spectra taken by the Scanning High-Resolution Interferometer Sounder (S-HIS) on two aircraft campaigns: the Mixed-Phase Arctic Cloud Experiment (MPACE) and the Aura Validation Experiment (AVE) both in Fall, 2004. Reasonable and consistent comparisons are illustrated, revealing that spectral radiance data taken by high-resolution infrared sounders can be used to determine the vertical distribution of radiative cooling due to CO_2

    On the next-to-leading-order correction to the effective action in N=2 gauge theories

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    I attempt to analyse the next-to-leading-order non-holomorphic contribution to the Wilsonian low-energy effective action in the four-dimensional N=2 gauge theories with matter, from the manifestly N=2 supersymmeric point of view, by using the harmonic superspace. The perturbative one-loop correction is found to be in agreement with the N=1 superfield calculations of de Wit, Grisaru and Rocek. The previously unknown coefficient in front of this non-holomorphic correction is calculated. A special attention is devoted to the N=2 superconformal gauge theories, whose one-loop non-holomorphic contribution is likely to be exact, even non-perturbatively. This leading (one-loop) non-holomorphic contribution to the LEEA of the N=2 superconformally invariant gauge field theories is calculated, and it does not vanish, similarly to the case of the N=4 super-Yang-Mills theory.Comment: 15 pages, LaTeX; changes in the abstract and in sect.

    Can radiographers be trained to triage CT colonography for extracolonic findings?

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    OBJECTIVES: Radiographers have been shown to be capable CT colonography observers. We evaluated whether radiographers can be trained to triage screening CT colonography for extracolonic findings. METHODS: Eight radiographers participated in a structured training program. They subsequently evaluated extracolonic findings in 280 low-dose CT colonograms (cases). This dataset contained 66 cases with possibly important findings (E3) and 27 cases with probably important findings (E4) [classification based on the highest classified finding (C-RADS)]. The first 40 and last 40 CT colonograms were identical test cases. Immediate feedback was given after each reading, except for test cases. Radiographers triaged cases based on C-RADS classification and indicated the need for a radiologist read. We constructed learning curves for correct case triaging by calculating moving averages. RESULTS: In the final test series, 84/120 (70 %) cases with E3 or E4 findings and 139/200 (70 %) without E3 or E4 findings were correctly triaged. Correct identification of cases with E3 findings improved with training from 46/88 (52 %) to 62/88 (70 %) (P < 0.0001) but not for E4 findings [both 22/32 (69 %) P = 1.00]. CONCLUSIONS: Radiographers improve after training in correctly triaging extracolonic findings at CT colonography but do not reach a high enough accuracy to consider their structural involvement in screening. KEY POINTS: • Radiographers were trained to triage CT colonography for extracolonic findings. • After training, radiographers improved sensitivity for likely unimportant findings. • After training, radiographers did not improve sensitivity for possibly important findings. • Radiographers should probably not be expected to identify all extracolonic findings
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