7,378 research outputs found

    Classical Three-Box "paradox"

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    A simple classical probabilistic system (a simple card game) classically exemplifies Aharonov and Vaidman's "Three-Box 'paradox'" [J. Phys. A 24, 2315 (1991)], implying that the Three-Box example is neither quantal nor a paradox and leaving one less difficulty to busy the interpreters of quantum mechanics. An ambiguity in the usual expression of the retrodiction formula is shown to have misled Albert, Aharonov, and D'Amato [Phys. Rev. Lett. 54, 5 (1985)] to a result not, in fact, "curious"; the discussion illustrates how to avoid this ambiguity.Comment: 10 pages. v4: As published, with corrections and updated reference

    Discovery of 11 New T Dwarfs in the Two Micron All-Sky Survey, Including a Possible L/T Transition Binary

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    We present the discovery of 11 new T dwarfs, found during the course of a photometric survey for mid-to-late T dwarfs in the 2MASS Point Source Catalog and from a proper motion selected sample of ultracool dwarfs in the 2MASS Working Database. Using the NASA Infrared Telescope Facility SpeX spectrograph, we obtained low-resolution (R~150) spectroscopy, allowing us to derive near-infrared spectral types of T2-T8. One of these new T dwarfs, 2MASS J13243559+6358284, was also discovered independently by Metchev et al., in prep. This object is spectroscopically peculiar and possibly a binary and/or very young (<300 Myr). We specifically attempted to model the spectrum of this source as a composite binary to reproduce its peculiar spectral characteristics. The latest-type object in our sample is a T8 dwarf, 2MASS J07290002-3954043, now one of the four latest-type T dwarfs known. All 11 T dwarfs are nearby given their spectrophotometric distance estimates, with 1 T dwarf within 10 pc and 8 additional T dwarfs within 25 pc, if single. These new additions increase the 25 pc census of T dwarfs by ~14%. Their proximity offers an excellent opportunity to probe for companions at closer separations than are possible for more distant T dwarfs.Comment: 45 pages, 9 figures, 9 tables. Published in AJ. Replacement: Fixed typos in 3 tables (some reported photometry was from the 2MASS Working Database instead of the 2MASS All Sky Catalog) and updated Fig.

    A Candidate Wide Brown Dwarf Binary in the Argus Association: 2MASS J14504216-7841413 and 2MASS J14504113-7841383

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    [not part of Research Note] We report the discovery of a widely-separated low-mass binary as a candidate member of the ∼\sim40 Myr Argus Association. Resolved imaging and astrometry with 2MASS and LDSS-3 reveal a common proper motion pair of red sources separated by 4.23''±\pm0.11'', with the secondary roughly one magnitude fainter at ii, zz and JJ. Resolved spectroscopy indicates component types of M8pec and M9pec, the peculiarities arising from weak Na I and strong VO absorption characteristic of low gravity sources. With its small proper motion and estimated 75±\pm25 pc distance, the BANYAN II tool indicates a membership probability of 93% in Argus, which would be consistent with a pair of brown dwarfs of mass ∼\sim0.04 M⊙_{\odot} separated by ∼\sim300 AU.Comment: 3 pages, 1 figure, accepted to Research Notes of the AA

    Personality and Happiness

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    The connection between personality, emotions, and experience have been of interest to researchers for many years. The present study was designed to assess the specific connection between personality, happiness, and happiness inducing behaviors (HIB) within individuals. This study also extends previous research by assessing whether any or all of these variables were connected to the recommendations an individual would make to improve the mood of a hypothetical other. The data from 424 university students were analyzed to determine the relationship between self-reported extraversion and neuroticism and self-reported affect, engagement in HIB, and the recommendations provided. The results revealed the expected positive correlation between extraversion, happiness, and engagement in HIB along with the expected negative correlation between neuroticism, happiness and engagement in HIB. Contrary to hypothesis, although there were differences in recommendations provided by those high or low in HIB, these differences did not indicate that those high in HIB made the most beneficial recommendations to help improve the mood of another. A discussion of the importance, implications, and limitations of the present study is provided

    Likelihood of Confusion Issues: The Federal Circuit\u27s Standard of Review

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    Clouds, Gravity, and Metallicity in Blue L Dwarfs: The Case of 2MASS J11263991–5003550

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    Optical and near-infrared spectroscopy of the newly discovered peculiar L dwarf 2MASS J11263991–5003550 are presented. Folkes et al. classified this source as a high proper motion L9±1 dwarf based on its strong H2O absorption at 1.4 μ m . We find that the optical spectrum of 2MASS J1126–5003 is in fact consistent with that of a normal L4.5 dwarf with notably enhanced FeH absorption at 9896 Å. However, its near-infrared spectrum is unusually blue, with strong H2O and weak CO bands similar in character to several recently identified "blue L dwarfs." Using 2MASS J1126–5003 as a case study, and guided by trends in the condensate cloud models of Burrows et al. and Marley et al., we find that the observed spectral peculiarities of these sources can be adequately explained by the presence of thin and/or large-grained condensate clouds as compared to normal field L dwarfs. Atypical surface gravities or metallicities alone cannot reproduce the observed peculiarities, although they may be partly responsible for the unusual condensate properties. We also rule out unresolved multiplicity as a cause for the spectral peculiarities of 2MASS J1126–5003. Our analysis is supported by examination of Spitzer mid-infrared spectral data from Cushing et al. which show that bluer L dwarfs tend to have weaker 10 μ m absorption, a feature tentatively associated with silicate oxide grains. With their unique spectral properties, blue L dwarfs like 2MASS J1126–5003 should prove useful in studying the formation and properties of condensates and condensate clouds in low-temperature atmospheres

    Aspects of the distribution, phytosociology, ecology and management of Danthonia popinensis D.I. Morris, an endangered wallaby grass from Tasmania

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    Danthonia popinensis is a recently discovered, nationally endangered tussock grass, originally known from only one roadside population at Kempton, Tasmania. Six populations have been recorded, all from flat land with mildly acid non-rocky soils, and all in small roadside or paddock remnants, badly invaded by exotic plants. However, one site has recently been destroyed through roadworks. The species germinates best at temperatures of 10°e, indicating a winter germination strategy. Autumn burning at Kempton resulted in an increased cover of D. popinensis two years after the burn, but also resulted in an increased cover of competitive exotics. The future of the species needs to be secured by ex situ plantings, as almost all of its original habitat has been converted to crops or improved pasture
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