3,773 research outputs found

    Aislamiento de un extracto de BMP y estudio anatomopatológico del fenómeno de inducción ósea tras su implante en defectos óseos

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    El objetivo del presente trabajo fue determinar el potencial osteogénico de la proteína morfogenética ósea (BMP) en la reparación de grandes defectos diafisarios. Además, se investiga la acción coadyuvante de la fibronectina (FN). La BMP fue extraída a partir de hueso cortical bovino. Se utilizaron un total de 108 ratas Sprague Dawley. En cada animal, se resecó un segmento de diáfisis femoral de 1.5 cm, siendo inmovilizado el defecto óseo con una aguja en omega. Se rellenó el defecto implantando 25 mg de BMP con o sin 0.5 mg de FN en una cápsula de gelatina (36 animales en ambos grupos). Los resultados se compararon con los obtenidos en otro grupo (36 animales) en el que sólo se implantó FN que sirvió como grupo control. El proceso de reparación se evaluó mediante métodos histológicos y ultraestructurales. La aparición del fenómeno de inducción ósea con reconstrucción del defecto óseo fue mayor en el grupo con implante de BMP más FN (23 animales, 64%) que en el grupo en el que sólo se implantó BMP (20 animales, 56%). Ningún animal del grupo control manifestaba signos de inducción ósea.The aim of the present work was to evaluate the osteogenic potential of Bone Morphogenetic Protein (BMP) for reparation of large segmental bone defects. In addition, the coadjuvant efect of fibronectin (FN) was investigated. BMP was partially purified from bovine cortical bone. A total of 108 Sprague Dawley rats were used in the experiment. Diaphyseal segments of the femur (1.5 cm) were removed in each animal, manteinant the bone defect with a wire. A gelatine capsula containing 25 mg of BMP without or with 0.5 mg of FN, were implanted into the bone defect (36 animal in each group). Results were compared to those obtained in a control group (36 animals) in which FN alone was implanted. The bone repair process was assessed by histologic and ultrastructural methods. Bone induction with reconstruction of the defect was found more of ten in the group with both BMP and FN implanted (23 animals, 64%) than in the group with BMP implant alone (20 animals, 56%). Animals of the control group showed no bone induction. The results suggest that BMP augments the capacity of the host bed to sucessfully regenerate large segmental bone defects. FN seens to increase bone induction. This protein migth stabilize BMP locally improving contact between BMP and the surrounding cells

    Calculation of The Band Gap Energy and Study of Cross Luminescence in Alkaline-Earth Dihalide Crystals

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    The band gap energy as well as the possibility of cross luminescence processes in alkaline-earth dihalide crystals have been calculated using the ab initio Perturbed-Ion (PI) model. The gap is calculated in several ways: as a difference between one-electron energy eigenvalues and as a difference between total energies of appropriate electronic states of the crystal, both at the HF level and with inclusion of Coulomb correlation effects. In order to study the possibility of ocurrence of cross luminescence in these materials, the energy difference between the valence band and the upmost core band for some representative crystals has been calculated. Both calculated band gap energies and cross luminescence predictions compare very well with the available experimental results.Comment: LaTeX file containing 8 pages plus 1 postscript figure. Final version accepted for publication in The Journal of the Physical Society of Japan. It contains a more complete list of references, as well as a more detailed comparison with previous theoretical investigations on the subjec

    UWISH2 -- The UKIRT Widefield Infrared Survey for H2

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    We present the goals and preliminary results of an unbiased, near-infrared, narrow-band imaging survey of the First Galactic Quadrant (10deg<l<65deg ; -1.3deg<b<+1.3deg). This area includes most of the Giant Molecular Clouds and massive star forming regions in the northern hemisphere. The survey is centred on the 1-0S(1) ro-vibrational line of H2, a proven tracer of hot, dense molecular gas in star-forming regions, around evolved stars, and in supernova remnants. The observations complement existing and upcoming photometric surveys (Spitzer-GLIMPSE, UKIDSS-GPS, JCMT-JPS, AKARI, Herschel Hi-GAL, etc.), though we probe a dynamically active component of star formation not covered by these broad-band surveys. Our narrow-band survey is currently more than 60% complete. The median seeing in our images is 0.73arcsec. The images have a 5sigma detection limit of point sources of K=18mag and the surface brightness limit is 10^-19Wm^-2arcsec^-2 when averaged over our typical seeing. Jets and outflows from both low and high mass Young Stellar Objects are revealed, as are new Planetary Nebulae and - via a comparison with earlier K-band observations acquired as part of the UKIDSS GPS - numerous variable stars. With their superior spatial resolution, the UWISH2 data also have the potential to reveal the true nature of many of the Extended Green Objects found in the GLIMPSE survey.Comment: 14pages, 8figures, 2tables, accepted for publication by MNRAS, a version with higher resolution figures can be found at http://astro.kent.ac.uk/~df

    Compressed representation of a partially defined integer function over multiple arguments

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    In OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one

    Design and rationale of DUTCH-AF:a prospective nationwide registry programme and observational study on long-term oral antithrombotic treatment in patients with atrial fibrillation

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    Introduction Anticoagulation therapy is pivotal in the management of stroke prevention in atrial fibrillation (AF). Prospective registries, containing longitudinal data are lacking with detailed information on anticoagulant therapy, treatment adherence and AF-related adverse events in practice-based patient cohorts, in particular for non-vitamin K oral anticoagulants (NOAC). With the creation of DUTCH-AF, a nationwide longitudinal AF registry, we aim to provide clinical data and answer questions on the (anticoagulant) management over time and of the clinical course of patients with newly diagnosed AF in routine clinical care. Within DUTCH-AF, our current aim is to assess the effect of non-adherence and non-persistence of anticoagulation therapy on clinical adverse events (eg, bleeding and stroke), to determine predictors for such inadequate anticoagulant treatment, and to validate and refine bleeding prediction models. With DUTCH-AF, we provide the basis for a continuing nationwide AF registry, which will facilitate subsequent research, including future registry-based clinical trials. Methods and analysis The DUTCH-AF registry is a nationwide, prospective registry of patients with newly diagnosed 'non-valvular' AF. Patients will be enrolled from primary, secondary and tertiary care practices across the Netherlands. A target of 6000 patients for this initial cohort will be followed for at least 2 years. Data on thromboembolic and bleeding events, changes in antithrombotic therapy and hospital admissions will be registered. Pharmacy-dispensing data will be obtained to calculate parameters of adherence and persistence to anticoagulant treatment, which will be linked to AF-related outcomes such as ischaemic stroke and major bleeding. In a subset of patients, anticoagulation adherence and beliefs about drugs will be assessed by questionnaire. Ethics and dissemination This study protocol was approved as exempt for formal review according to Dutch law by the Medical Ethics Committee of the Leiden University Medical Centre, Leiden, the Netherlands. Results will be disseminated by publications in peer-reviewed journals and presentations at scientific congresses

    Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

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    A measurement of the cosmic-ray spectrum for energies exceeding 4×10184{\times}10^{18} eV is presented, which is based on the analysis of showers with zenith angles greater than 6060^{\circ} detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above 5.3×10185.3{\times}10^{18} eV, the "ankle", the flux can be described by a power law EγE^{-\gamma} with index γ=2.70±0.02(stat)±0.1(sys)\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)} followed by a smooth suppression region. For the energy (EsE_\text{s}) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find Es=(5.12±0.25(stat)1.2+1.0(sys))×1019E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19} eV.Comment: Replaced with published version. Added journal reference and DO

    Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

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    The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
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