375 research outputs found

    Necrosis avascular de cabeza femoral en pacientes con enfermedad de Gaucher tipo I : tratamiento mediante artroplastia total de cadera no cementada

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    El 80% de los pacientes con enfermedad de Gaucher presentan manifestaciones óseas, siendo la necrosis avascular de la cabeza femoral una de las que mayor limitación produce y la primera causa de intervención quirúrgica osteoarticular. La artroplastia total de cadera cementada ha sido el tratamiento de elección en los casos con mayor deterioro de la articulación, pero sus resultados a medio y largo plazo se han visto ensombrecidos por la elevada tasa de aflojamiento. La terapia enzimática sustitutiva ha disminuido las complicaciones postoperatorias, además de permitir el uso de componentes no cementados con resultados similares a las prótesis implantadas por otros motivos. Presentamos una serie de 5 artroplastias de cadera no cementadas, con un seguimiento medio de 12.4 años (3.4-30), en 4 pacientes con enfermedad de Gaucher tipo I y osteonecrosis de la cabeza femoral. Solo se observó un caso de aflojamiento aséptico a los 18 años de la intervención

    e-INEBRIA special interest group roadmap to best practices for practice and research on brief digital interventions for problematic alcohol and illicit drug use

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    Background: There is huge potential for scaling up the delivery of brief interventions for alcohol and illicit drug use, given the increasing coverage and technologies of e-digital interventions, including applications for smartphones and tablets. However, while the quantity of digital interventions is increasing rapidly, the involvement of brief-intervention researchers and the development of good practices has just begun. Roadmap: In 2018, the Special Interest Group on digital interventions from the International Network on Brief Interventions for Alcohol & Other Drugs (e-INEBRIA SIG) initiated a conversation on possible avenues of future research, which subsequently turned into a roadmap for digital interventions during further discussions. This roadmap consists of points considered relevant for future research, ongoing technological developments, and their implementation across a continuum of prevention and care. Moreover, it outlines starting points for the diversification of brief digital interventions, as well as next steps for quality improvement and implementation in public health and clinical practice. Conclusions: The roadmap of the e-INEBRIA SIG on digital interventions is a starting point that indicates relevant next steps and provides orientation for researchers and interested practitioners in the ambiguous literature and complexity of current digital interventions

    Asteroseismology with the WIRE satellite. I. Combining Ground- and Space-based Photometry of the Delta Scuti Star Epsilon Cephei

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    We have analysed ground-based multi-colour Stromgren photometry and single-filter photometry from the star tracker on the WIRE satellite of the delta scuti star Epsilon Cephei. The ground-based data set consists of 16 nights of data collected over 164 days, while the satellite data are nearly continuous coverage of the star during 14 days. The spectral window and noise level of the satellite data are superior to the ground-based data and this data set is used to locate the frequencies. However, we can use the ground-based data to improve the accuracy of the frequencies due to the much longer time baseline. We detect 26 oscillation frequencies in the WIRE data set, but only some of these can be seen clearly in the ground-based data. We have used the multi-colour ground-based photometry to determine amplitude and phase differences in the Stromgren b-y colour and the y filter in an attempt to identify the radial degree of the oscillation frequencies. We conclude that the accuracies of the amplitudes and phases are not sufficient to constrain theoretical models of Epsilon Cephei. We find no evidence for rotational splitting or the large separation among the frequencies detected in the WIRE data set. To be able to identify oscillation frequencies in delta scuti stars with the method we have applied, it is crucial to obtain more complete coverage from multi-site campaigns with a long time baseline and in multiple filters. This is important when planning photometric and spectroscopic ground-based support for future satellite missions like COROT and KEPLER.Comment: 13 pages, 12 figures, 4 tables. Fig. 4 reduced in quality. Accepted by A&

    Enantiopure 4‐oxazolin‐2‐ones and 4‐methylene‐2‐oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles

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    En este trabajo se describe la reactividad de las oxazolidin-2-onas en un ambiente quiral obteniéndose resultados novedosos, los cuales se describen extensamente.Enantiopure 3‐((R)‐ and 3‐((S)‐1‐phenylethyl)‐4‐oxazoline‐2‐ones were evaluated as chiral building blocks for the divergent construction of heterocycles with stereogenic quaternary centers. The N‐(R)‐ or N‐(S)‐1‐phenylethyl group of these compounds proved to be an efficient chiral auxiliary for the asymmetric induction of the 4‐ and 5‐positions of the 4‐oxazolin‐2‐one ring through thermal and MW‐promoted nucleophilic conjugated addition to Michael acceptors and alkyl halides. The resulting adducts were transformed via a cascade process into fused six‐membered carbo‐ and heterocycles. The structure of the reaction products depended on the electrophiles and reaction conditions used. Alternative isomeric 4‐methylene‐2‐oxazolidinones served as chiral precursors for a versatile and divergent approach to highly substituted cyclic carbamates. DFT quantum calculations showed that the formation of bicyclic pyranyl compounds was generated by a diastereoselective concerted hetero‐Diels‐Alder cycloaddition.Instituto Politécnico Nacional, Secretaria de Investigación y Estudios Avanzados de la Universidad Autónoma del Estado de México, Universidad de Guanajuato y CONACYT

    All-particle cosmic ray energy spectrum measured by the HAWC experiment from 10 to 500 TeV

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    We report on the measurement of the all-particle cosmic ray energy spectrum with the High Altitude Water Cherenkov (HAWC) Observatory in the energy range 10 to 500 TeV. HAWC is a ground based air-shower array deployed on the slopes of Volcan Sierra Negra in the state of Puebla, Mexico, and is sensitive to gamma rays and cosmic rays at TeV energies. The data used in this work were taken from 234 days between June 2016 to February 2017. The primary cosmic-ray energy is determined with a maximum likelihood approach using the particle density as a function of distance to the shower core. Introducing quality cuts to isolate events with shower cores landing on the array, the reconstructed energy distribution is unfolded iteratively. The measured all-particle spectrum is consistent with a broken power law with an index of 2.49±0.01-2.49\pm0.01 prior to a break at (45.7±0.1(45.7\pm0.1) TeV, followed by an index of 2.71±0.01-2.71\pm0.01. The spectrum also respresents a single measurement that spans the energy range between direct detection and ground based experiments. As a verification of the detector response, the energy scale and angular resolution are validated by observation of the cosmic ray Moon shadow's dependence on energy.Comment: 16 pages, 11 figures, 4 tables, submission to Physical Review

    The International Cannabis Toolkit (iCannToolkit) : A multidisciplinary expert consensus on minimum standards for measuring cannabis use

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    Background The lack of an agreed international minimum approach to measuring cannabis use hinders the integration of multidisciplinary evidence on the psychosocial, neurocognitive, clinical and public health consequences of cannabis use. Methods A group of 25 international expert cannabis researchers convened to discuss a multidisciplinary framework for minimum standards to measure cannabis use globally in diverse settings. Results The expert-based consensus agreed upon a three-layered hierarchical framework. Each layer—universal measures, detailed self-report and biological measures—reflected different research priorities and minimum standards, costs and ease of implementation. Additional work is needed to develop valid and precise assessments. Conclusions Consistent use of the proposed framework across research, public health, clinical practice and medical settings would facilitate harmonisation of international evidence on cannabis consumption, related harms and approaches to their mitigation

    Observation of the Crab Nebula with the HAWC Gamma-Ray Observatory

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    The Crab Nebula is the brightest TeV gamma-ray source in the sky and has been used for the past 25 years as a reference source in TeV astronomy, for calibration and verification of new TeV instruments. The High Altitude Water Cherenkov Observatory (HAWC), completed in early 2015, has been used to observe the Crab Nebula at high significance across nearly the full spectrum of energies to which HAWC is sensitive. HAWC is unique for its wide field-of-view, nearly 2 sr at any instant, and its high-energy reach, up to 100 TeV. HAWC's sensitivity improves with the gamma-ray energy. Above \sim1 TeV the sensitivity is driven by the best background rejection and angular resolution ever achieved for a wide-field ground array. We present a time-integrated analysis of the Crab using 507 live days of HAWC data from 2014 November to 2016 June. The spectrum of the Crab is fit to a function of the form ϕ(E)=ϕ0(E/E0)αβln(E/E0)\phi(E) = \phi_0 (E/E_{0})^{-\alpha -\beta\cdot{\rm{ln}}(E/E_{0})}. The data is well-fit with values of α=2.63±0.03\alpha=2.63\pm0.03, β=0.15±0.03\beta=0.15\pm0.03, and log10(ϕ0 cm2 s TeV)=12.60±0.02_{10}(\phi_0~{\rm{cm}^2}~{\rm{s}}~{\rm{TeV}})=-12.60\pm0.02 when E0E_{0} is fixed at 7 TeV and the fit applies between 1 and 37 TeV. Study of the systematic errors in this HAWC measurement is discussed and estimated to be ±\pm50\% in the photon flux between 1 and 37 TeV. Confirmation of the Crab flux serves to establish the HAWC instrument's sensitivity for surveys of the sky. The HAWC survey will exceed sensitivity of current-generation observatories and open a new view of 2/3 of the sky above 10 TeV.Comment: Submitted 2017/01/06 to the Astrophysical Journa

    Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth

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    The unexpectedly high flux of cosmic ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the HighAltitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera-electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.Comment: 16 pages (including supplementary material), 5 figure

    Constraining the pˉ/p\bar{p}/p Ratio in TeV Cosmic Rays with Observations of the Moon Shadow by HAWC

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    An indirect measurement of the antiproton flux in cosmic rays is possible as the particles undergo deflection by the geomagnetic field. This effect can be measured by studying the deficit in the flux, or shadow, created by the Moon as it absorbs cosmic rays that are headed towards the Earth. The shadow is displaced from the actual position of the Moon due to geomagnetic deflection, which is a function of the energy and charge of the cosmic rays. The displacement provides a natural tool for momentum/charge discrimination that can be used to study the composition of cosmic rays. Using 33 months of data comprising more than 80 billion cosmic rays measured by the High Altitude Water Cherenkov (HAWC) observatory, we have analyzed the Moon shadow to search for TeV antiprotons in cosmic rays. We present our first upper limits on the pˉ/p\bar{p}/p fraction, which in the absence of any direct measurements, provide the tightest available constraints of 1%\sim1\% on the antiproton fraction for energies between 1 and 10 TeV.Comment: 10 pages, 5 figures. Accepted by Physical Review
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