3,348 research outputs found

    The origin and prevention of pandemics.

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    Despite the fact that most emerging diseases stem from the transmission of pathogenic agents from animals to humans, the factors that mediate this process are still ill defined. What is known, however, is that the interface between humans and animals is of paramount importance in the process. This review will discuss the importance of the human-animal interface to the disease emergence process. We also provide an overview of factors that are believed to contribute to the origin and global spread of emerging infectious diseases and offer suggestions that may serve as future prevention strategies, such as social mobilization, public health education, behavioral change, and communication strategies. Because there exists no comprehensive global surveillance system to monitor zoonotic disease emergence, the intervention measures discussed herein may prove effective temporary alternatives

    Rhythm and Vowel Quality in Accents of English

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    In a sample of 27 speakers of Scottish Standard English two notoriously variable consonantal features are investigated: the contrast of /m/ and /w/ and non-prevocalic /r/, the latter both in terms of its presence or absence and the phonetic form it takes, if present. The pattern of realisation of non-prevocalic /r/ largely confirms previously reported findings. But there are a number of surprising results regarding the merger of /m/ and /w/ and the loss of non-prevocalic /r/: While the former is more likely to happen in younger speakers and females, the latter seems more likely in older speakers and males. This is suggestive of change in progress leading to a loss of the /m/ - /w/ contrast, while the variation found in non-prevocalic /r/ follows an almost inverse sociolinguistic pattern that does not suggest any such change and is additionally largely explicable in language-internal terms. One phenomenon requiring further investigation is the curious effect direct contact with Southern English accents seems to have on non-prevocalic /r/: innovation on the structural level (i.e. loss) and conservatism on the realisational level (i.e. increased incidence of [r] and [r]) appear to be conditioned by the same sociolinguistic factors

    Effect of high temperature heat treatments on the quality factor of a large-grain superconducting radio-frequency niobium cavity

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    Large-grain Nb has become a viable alternative to fine-grain Nb for the fabrication of superconducting radio-frequency cavities. In this contribution we report the results from a heat treatment study of a large-grain 1.5 GHz single-cell cavity made of "medium purity" Nb. The baseline surface preparation prior to heat treatment consisted of standard buffered chemical polishing. The heat treatment in the range 800 - 1400 C was done in a newly designed vacuum induction furnace. Q0 values of the order of 2x1010 at 2.0 K and peak surface magnetic field (Bp) of 90 mT were achieved reproducibly. A Q0-value of (5+-1)1010 at 2.0 K and Bp = 90 mT was obtained after heat treatment at 1400 C. This is the highest value ever reported at this temperature, frequency and field. Samples heat treated with the cavity at 1400 C were analyzed by secondary ion mass spectrometry, secondary electron microscopy, energy dispersive X-ray, point contact tunneling and X-ray diffraction and revealed a complex surface composition which includes titanium oxide, increased carbon and nitrogen content but reduced hydrogen concentration compared to a non heat-treated sample

    Fundamental stellar parameters of zeta Pup and gamma^2 Vel from HIPPARCOS data

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    We report parallax measurements by the HIPPARCOS satellite of zeta Puppis and gamma^2 Velorum. The distance of zeta Pup is d=429 (+120/ -77) pc, in agreement with the commonly adopted value to Vela OB2. However, a significantly smaller distance is found for the gamma^2 Vel system: d=258 (+41/-31) pc. The total mass of gamma^2 Vel derived from its parallax, the angular size of the semi-major axis as measured with intensity interferometry, and the period is M(WR+O)=29.5 (+/-15.9) Msun. This result favors the orbital solution of Pike et al. (1983) over that of Moffat et al. (1986). The stellar parameters for the O star companion derived from line blanketed non-LTE atmosphere models are: Teff=34000 (+/-1500) K, log L/Lsun=5.3 (+/-0.15) from which an evolutionary mass of M=29 (+/-4) Msun and an age of 4.0 (+0.8/-0.5) Myr is obtained from single star evolutionary models. With non-LTE model calculations including He and C we derive a luminosity log L/Lsun~4.7 (+/-0.2) for the WR star. The mass-luminosity relation of hydrogen-free WR stars implies a mass of M(WR)~5 (+/-1.5) Msun. From our data we favor an age of ~10 Myr for the bulk of the Vela OB2 stars. Evolutionary scenarios for zeta Pup and gamma^2 Vel are discussed in the light of our results.Comment: Submitted to ApJ Letters (misprints corrected

    Fractal dimensions of the Q-state Potts model for the complete and external hulls

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    Fortuin-Kastelyn clusters in the critical QQ-state Potts model are conformally invariant fractals. We obtain simulation results for the fractal dimension of the complete and external (accessible) hulls for Q=1, 2, 3, and 4, on clusters that wrap around a cylindrical system. We find excellent agreement between these results and theoretical predictions. We also obtain the probability distributions of the hull lengths and maximal heights of the clusters in this geometry and provide a conjecture for their form.Comment: 9 pages 4 figure

    Toward an understanding of risk factors for anorexia nervosa: A case-control study

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    Prospective, longitudinal studies of risk factors for anorexia nervosa (AN) are lacking and existing cross-sectional studies are generally narrow in focus and lack methodological rigor. Building on two studies that used the Oxford Risk Factor Interview (RFI) to establish time precedence and comprehensively assess potential risk correlates for AN, the present study advances this line of research and represents the first case-control study of risk factors for AN in the USA
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