2,006 research outputs found

    William Buelow Gould - Convict artist in Van Diemen's Land

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    When I came first to the Launceston Museum I found very many paintings by a convict named Gould. Very soon visitors were asking me questions about him and I proceeded to read what had been written. It seemed very little. In fact, it amounted to the notes that had been put together by Mr. Henry Allport for an exhibition of Tasmanian art held in Hobart in 1931. These notes were published in the " Mercury " newspaper and then put together in pamphlet form. Every subsequent writer on Gould has used them. When people said, however," when was he born? When did he die? Was he married? Did he leave any family? Did he paint only in oil?", I had to reply, "I do not know." I am still not certain when he was born, but I know when he died. When people asked, "Where did Gould live?", I said, vaguely, "Hobart . Then, one day, looking through some records in the Museum, I found that William Buelow Gould was before R. C. Gunn, Magistrate, here in Launceston, for being drunk. So he wasn't only in Hobart. He was also in Launceston and, I found later, at Macquarie Harbour, at Port Arthur, at Bridgewater, and at Jericho. Then-was he married? Did he have a family? Yes. Did he paint only in oil? No, he used watercolour too, much more effectively than he did oil. So I got together gradually some kind of picture of this early artist. Of Gould's early life very little is still known. Actually his name was Holland, not Gould

    The effect of exercise on depressive symptoms in adolescents: a systematic review and meta-analysis

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    Objective: The purpose of this review was to examine the treatment effect of physical exercise on depressive symptoms for adolescents aged 13 to 17 years. Method: A systematic search of 7 electronic databases identified relevant randomized controlled trials. Following removal of duplicates, 543 texts were screened for eligibility. Screening, data extraction, and trial methodological quality assessment (using the Delphi list) were undertaken by 2 independent researchers. Standardized mean differences were used for pooling postintervention depressive symptom scores. Results: Eleven trials met the inclusion criteria, 8 of which provided the necessary data for calculation of standardized effect size. Exercise showed a statistically significant moderate overall effect on depressive symptom reduction (standardized mean difference [SMD] = −0.48, 95% CI = −0.87, −0.10, p = .01, I2 = 67%). Among trials with higher methodological scoring, a nonsignificant moderate effect was recorded (SMD = −0.41, 95% CI = −0.86, 0.05, p = .08). In trials with exclusively clinical samples, exercise showed a statistically significant moderate effect on depressive symptoms with lower levels of heterogeneity (SMD = −0.43, 95% CI = −0.84, −0.02, p = .04, I2 = 44%). Conclusion: Physical exercise appears to improve depressive symptoms in adolescents, especially in clinical samples in which the moderate antidepressant effect, higher methodological quality, and lowered statistical heterogeneity suggest that exercise may be a useful treatment strategy for depression. Larger trials with clinical samples that adequately minimize the risk of bias are required for firmer conclusions on the effectiveness of exercise as an antidepressant treatment

    Resonance tunneling of polaritons in 1-D chain with a single defect

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    We consider propagation of coupled waves (polaritons) formed by a scalar electromagnetic wave and excitations of a finite one dimensional chain of dipoles. It is shown that a microscopic defect (an impurity dipole) embedded in the chain causes resonance tunneling of the electromagnetic wave with the frequency within the forbidden band between two polariton branches. We demonstrate that resonance tunneling occurs due to local polariton states caused by the defect.Comment: 11 pages, 9 figures (PS-format), RevTe

    Sommerfeld enhancement from Goldstone pseudo-scalar exchange

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    We point out that the exchange of a Goldstone pseudo-scalar can provide an enhancement in the dark matter annihilation rate capable of explaining the excess flux seen in high energy cosmic ray data. The mechanism of enhancement involves the coupling of s and d waves through the tensor force that is very strong and, in fact, singular at short distances. The results indicate that large enhancements require some amount of fine tuning. We also discuss the enhancement due to other singular attractive potentials, such as WIMP models with a permanent electric dipole.Comment: 14 pages, 4 figures, v2 includes contact informatio

    Local Polariton States in Polar Crystals with Impurities

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    We show that an impurity embedded in an ionic crystal can give rise to a novel kind of local states. These states exist within a polariton gap of a material and are a mix of excitations of the crystal, such as phonons or excitons, and the transverse electromagnetic field. The electromagnetic component of the states along with the corresponding excitations of the material are localized in the vicinity of an impurity.Comment: 9 pages, RevTe

    Effects of resonant tunneling in electromagnetic wave propagation through a polariton gap

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    We consider tunneling of electromagnetic waves through a polariton band gap of a 1-D chain of atoms. We analytically show that a defect embedded in the structure gives rise to the resonance transmission at the frequency of a local polariton state associated with the defect. Numerical Monte-Carlo simulations are used to examine properties of the electromagnetic band arising inside the polariton gap due to finite concentration of defects.Comment: 12 pages, 6 figures, RevTe

    Higher order dilaton gravity: brane equations of motion in the covariant formulation

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    Dilaton gravity with general brane localized interactions is investigated. Models with corrections up to arbitrary order in field derivatives are considered. Effective gravitational equations of motion at the brane are derived in the covariant approach. Dependence of such brane equations on the bulk quantities is discussed. It is shown that the number of the bulk independent brane equations of motion depends strongly on the symmetries assumed for the model and for the background. Examples with two and four derivatives of the fields are presented in more detail.Comment: 32 pages, references added, discussion extended, typos corrected, version to be publishe

    Impurity-induced polaritons in a one-dimensional chain

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    A detailed analytical study of an impurity induced polariton band arising inside a spectral gap between lower and upper polariton branches is presented. Using the microcanonical method, we calculate the density of states and localization length of the impurity polaritons. Analytical results are compared with numerical simulations and excellent agreement is found.Comment: 10 pages, 3 figures, RevTe
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