661 research outputs found

    Observation of Quantum Effects in sub Kelvin Cold Reactions

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    There has been a long-standing quest to observe chemical reactions at low temperatures where reaction rates and pathways are governed by quantum mechanical effects. So far this field of Quantum Chemistry has been dominated by theory. The difficulty has been to realize in the laboratory low enough collisional velocities between neutral reactants, so that the quantum wave nature could be observed. We report here the first realization of merged neutral supersonic beams, and the observation of clear quantum effects in the resulting reactions. We observe orbiting resonances in the Penning ionization reaction of argon and molecular hydrogen with metastable helium leading to a sharp increase in the absolute reaction rate in the energy range corresponding to a few degrees kelvin down to 10 mK. Our method is widely applicable to many canonical chemical reactions, and will enable a breakthrough in the experimental study of Quantum Chemistry

    Variation in survival after diagnosis of breast cancer in Switzerland

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    Background: Survival after diagnosis of cancer is a key criterion for cancer control. Major survival differences between time periods and countries have been reported by the EUROCARE studies. We investigated whether similar differences by period and region existed in Switzerland. Methods: Survival of 11 376 cases of primary invasive female breast cancer diagnosed between 1988 and 1997 and registered in seven Swiss cancer registries covering a population of 3.5 million was analysed. Results: Comparing the two periods 1988-1992 and 1993-1997, age-standardized 5 year relative survival improved globally from 77% to 81%. Furthermore, multivariate analysis adjusting for age, tumour size and nodal involvement identified regional survival differences. Survival was lowest in the rural parts of German-speaking eastern Switzerland and highest in urbanised regions of the Latin- and German-speaking northwestern parts of the country. Conclusions: This study confirms that survival differences are present even in a small and affluent, but culturally diverse, country like Switzerland, raising the issue of heterogeneity in access to care and quality of treatmen

    Design of a five-axis ultra-precision micro-milling machine—UltraMill. Part 1: Holistic design approach, design considerations and specifications

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    High-accuracy three-dimensional miniature components and microstructures are increasingly in demand in the sector of electro-optics, automotive, biotechnology, aerospace and information-technology industries. A rational approach to mechanical micro machining is to develop ultra-precision machines with small footprints. In part 1 of this two-part paper, the-state-of-the-art of ultra-precision machines with micro-machining capability is critically reviewed. The design considerations and specifications of a five-axis ultra-precision micro-milling machine—UltraMill—are discussed. Three prioritised design issues: motion accuracy, dynamic stiffness and thermal stability, formulate the holistic design approach for UltraMill. This approach has been applied to the development of key machine components and their integration so as to achieve high accuracy and nanometer surface finish

    Survival patterns in cystic fibrosis

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    This paper describes the Data Registry System of the Cystic Fibrosis Foundation. Through this system an annual up-dated and corrected data base has been prepared for cystic fibrosis patients seen at U.S.A. Centers from 1966 through 1972.From the data base, a large number of life table studies are calculated. A study is specified by its data base, the observation period, analysis year (age year or year since diagnosis), the Centers included, and the condition of patients at birth, and possible additional factors such as sex, age at diagnosis, or race. The annual rates of mortality are measured by a force of mortality technique.Two techniques have been used to appraise the mortality of particular groups, graphing the cumulative survival function for the group together with the cumulative survival function for a comparison group, and calculation of mortality ratios of actual to expected deaths (by an applicable standard mortality table). This latter approach lends itself readily to tests of significance.For the purpose of calculating mortality ratios, two standard tables have been prepared on the basis of the 1972 Data Base and the 1966-1972 observations. The first of these standard tables is for use with age year studies, and the second is for years since diagnosis studies.The paper comments on a number of mortality studies by calendar year, by sex, by condition at birth, by age at diagnosis, and of survival from diagnosis of patients diagnosed in 1966-1972. The calendar year studies indicate an improvement trend in the survival experience from 1966 to 1972 but a change may be occurring. The study by sex exhibits a higher female mortality. The 7% of patients who have meconium ileus at birth show a significantly higher first-year mortality, and a somewhat lower survival rate thereafter even if the first year of life experience is excluded. Mortality data for groups specified by age at diagnosis are given. For patients diagnosed during 1966-1972, there is some indication of better survival than for patients diagnosed prior to 1966.The continuation of these mortality studies on an annual basis should further our understanding of survival patterns for cystic fibrosis patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21939/1/0000346.pd

    The Song Describer dataset: a corpus of audio captions for music-and-language evaluation

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    We introduce the Song Describer dataset (SDD), a new crowdsourced corpus of high-quality audio-caption pairs, designed for the evaluation of music-and-language models. The dataset consists of 1.1k human-written natural language descriptions of 706 music recordings, all publicly accessible and released under Creative Common licenses. To showcase the use of our dataset, we benchmark popular models on three key music-and-language tasks (music captioning, text-to-music generation and music-language retrieval). Our experiments highlight the importance of cross dataset evaluation and offer insights into how researchers can use SDD to gain a broader understanding of model performance

    Women and Illegal Activities: Gender Differences and Women's Willingness to Comply Over Time

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    In recent years the topics of illegal activities such as corruption or tax evasion have attracted a great deal of attention. However, there is still a lack of substantial empirical evidence about the determinants of compliance. The aim of this paper is to investigate empirically whether women are more willing to be compliant than men and whether we observe (among women and in general) differences in attitudes among similar age groups in different time periods (cohort effect) or changing attitudes of the same cohorts over time (age effect) using data from eight Western European countries from the World Values Survey and the European Values Survey that span the period from 1981 to 1999. The results reveal higher willingness to comply among women and an age rather than a cohort effect. Working Paper 06-5

    Crystal and electronic structures of A2NaIO6 periodate double perovskites (A = Sr, Ca, Ba): candidate wasteforms for I-129 immobilization

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    The synthesis, structure, and thermal stability of the periodate double perovskites A2NaIO6 (A= Ba, Sr, Ca) were investigated in the context of potential application for the immobilization of radioiodine. A combination of X-ray diffraction and neutron diffraction, Raman spectroscopy, and DFT simulations were applied to determine accurate crystal structures of these compounds and understand their relative stability. The compounds were found to exhibit rock-salt ordering of Na and I on the perovskite B-site; Ba2NaIO6 was found to adopt the Fm-3m aristotype structure, whereas Sr2NaIO6 and Ca2NaIO6 adopt the P21/n hettotype structure, characterized by cooperative octahedral tilting. DFT simulations determined the Fm-3m and P21/n structures of Ba2NaIO6 to be energetically degenerate at room temperature, whereas diffraction and spectroscopy data evidence only the presence of the Fm-3m phase at room temperature, which may imply an incipient phase transition for this compound. The periodate double perovskites were found to exhibit remarkable thermal stability, with Ba2NaIO6 only decomposing above 1050 °C in air, which is apparently the highest recorded decomposition temperature so far recorded for any iodine bearing compound. As such, these compounds offer some potential for application in the immobilization of iodine-129, from nuclear fuel reprocessing, with an iodine incorporation rate of 25–40 wt%. The synthesis of these compounds, elaborated here, is also compatible with both current conventional and future advanced processes for iodine recovery from the dissolver off-gas

    Primeval very low-mass stars and brown dwarfs - III. The halo transitional brown dwarfs

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    This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.We report the discovery of an esdL3 subdwarf, ULAS J020858.62+020657.0 and a usdL4.5 subdwarf, ULAS J230711.01+014447.1. They were identified as L subdwarfs by optical spectra obtained with the Gran Telescopio Canarias, and followed up by optical to near infrared spectroscopy with the Very Large Telescope. We also obtained an optical to near infrared spectrum of a previously known L subdwarf, ULAS J135058.85+081506.8, and re-classified it as a usdL3 subdwarf. These three objects all have typical halo kinematics. They have TeffT_{\rm eff} around 2050-2250 K, -1.8 \leq [Fe/H] \leq -1.5, and mass around 0.0822-0.0833 M_{\odot}, according to model spectral fitting and evolutionary models. These sources are likely halo transitional brown dwarfs with unsteady hydrogen fusions, as their masses are just below the hydrogen-burning minimum mass, which is \sim 0.0845 M_{\odot} at [Fe/H] = -1.6 and \sim 0.0855 M_{\odot} at [Fe/H] = -1.8. Including these, there are now nine objects in the `halo brown dwarf transition zone', which is a `substellar subdwarf gap' spans a wide temperature range within a narrow mass range of the substellar population.Peer reviewedFinal Accepted Versio
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