1,587 research outputs found

    The rise-time of type II supernovae

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    We investigate the early-time light-curves of a large sample of 223 type II supernovae (SNe) from the Sloan Digital Sky Survey and the Supernova Legacy Survey. Having a cadence of a few days and sufficient non-detections prior to explosion, we constrain rise-times, i.e. the durations from estimated first to maximum light, as a function of effective wavelength. At restframe g-band (4722A), we find a distribution of fast rise-times with median of (7.5+/-0.3) days. Comparing these durations with analytical shock models of Rabinak and Waxman (2013); Nakar and Sari (2010) and hydrodynamical models of Tominaga et al. (2009), which are mostly sensitive to progenitor radius at these epochs, we find a median characteristic radius of less than 400 solar radii. The inferred radii are on average much smaller than the radii obtained for observed red supergiants (RSG). Investigating the post-maximum slopes as a function of effective wavelength in the light of theoretical models, we find that massive hydrogen envelopes are still needed to explain the plateaus of SNe II. We therefore argue that the SN II rise-times we observe are either a) the shock cooling resulting from the core collapse of RSG with small and dense envelopes, or b) the delayed and prolonged shock breakout of the collapse of a RSG with an extended atmosphere or embedded within pre-SN circumstellar material.Fil: González Gaitán, S.. Universidad de Chile; Chile. Millennium Institute of Astrophysics; ChileFil: Tominaga, N.. Konan University; JapónFil: Molina, J.. Universidad de Chile; ChileFil: Galbany, L.. Universidad de Chile; Chile. Millennium Institute of Astrophysics; ChileFil: Bufano, F.. Universidad Andres Bello; Chile. Millennium Institute of Astrophysics; ChileFil: Anderson, J. P. . European Southern Observatory; ChileFil: Gutierrez, C.. Universidad de Chile; Chile. Millennium Institute of Astrophysics; ChileFil: Förster, F.. Millennium Institute of Astrophysics; Chile. Universidad de Chile; ChileFil: Pignata, G.. Universidad Andres Bello; Chile. Millennium Institute of Astrophysics; ChileFil: Bersten, Melina Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. University of Tokyo; JapónFil: Howell, D. A. . Las Cumbres Observatory Global Telescope Network; Estados Unidos. University of California; Estados UnidosFil: Sullivan, M.. University of Southampton; Reino UnidoFil: Carlberg, R.. University Of Toronto; CanadáFil: De Jaeger, T. . Universidad de Chile; Chile. Millennium Institute of Astrophysics; ChileFil: Hamuy, M.. Universidad de Chile; Chile. Millennium Institute of Astrophysics; ChileFil: Baklanov, P. V. . Novosibirsk State University; RusiaFil: Blinnikov, S. I. . University of Tokyo; Japó

    Mental impact of Covid-19 among Spanish healthcare workers. A large longitudinal survey

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    Aims: Longitudinal data on the mental health impact of the coronavirus disease 2019 (Covid-19) pandemic in healthcare workers is limited. We estimated prevalence, incidence and persistence of probable mental disorders in a cohort of Spanish healthcare workers (Covid-19 waves 1 and 2) -and identified associated risk factors. Methods: 8996 healthcare workers evaluated on 5 May-7 September 2020 (baseline) were invited to a second web-based survey (October-December 2020). Major depressive disorder (PHQ-8 ≥ 10), generalised anxiety disorder (GAD-7 ≥ 10), panic attacks, post-traumatic stress disorder (PCL-5 ≥ 7), and alcohol use disorder (CAGE-AID ≥ 2) were assessed. Distal (pre-pandemic) and proximal (pandemic) risk factors were included. We estimated the incidence of probable mental disorders (among those without disorders at baseline) and persistence (among those with disorders at baseline). Logistic regression of individual-level [odds ratios (OR)] and population-level (population attributable risk proportions) associations were estimated, adjusting by all distal risk factors, health care centre and time of baseline interview. Results: 4809 healthcare workers participated at four months follow-up (cooperation rate = 65.7%; mean = 120 days s.d. = 22 days from baseline assessment). Follow-up prevalence of any disorder was 41.5%, (v. 45.4% at baseline, p < 0.001); incidence, 19.7% (s.e. = 1.6) and persistence, 67.7% (s.e. = 2.3). Proximal factors showing significant bivariate-adjusted associations with incidence included: work-related factors [prioritising Covid-19 patients (OR = 1.62)], stress factors [personal health-related stress (OR = 1.61)], interpersonal stress (OR = 1.53) and financial factors [significant income loss (OR = 1.37)]. Risk factors associated with persistence were largely similar. Conclusions: Our study indicates that the prevalence of probable mental disorders among Spanish healthcare workers during the second wave of the Covid-19 pandemic was similarly high to that after the first wave. This was in good part due to the persistence of mental disorders detected at the baseline, but with a relevant incidence of about 1 in 5 of HCWs without mental disorders during the first wave of the Covid-19 pandemic. Health-related factors, work-related factors and interpersonal stress are important risks of persistence of mental disorders and of incidence of mental disorders. Adequately addressing these factors might have prevented a considerable amount of mental health impact of the pandemic among this vulnerable population. Addressing health-related stress, work-related factors and interpersonal stress might reduce the prevalence of these disorders substantially. Study registration number: NCT04556565.Instituto de Salud Carlos III/ Ministerio de Ciencia e Innovación/ FEDER (J. A., grant number COV20/00711); Project “PI17/00521”, funded by Instituto de Salud Carlos III (ISCIII) and co-funded by the European Union, PERIS, Health Dpt, Generaliat de Catalunya (I. A., grant number SLT017/20/000009); ISCIII-FSE+, Miguel Servet (P. M., grant number CP21/00078); ISCIII-FSE, Sara Borrell (P. M., grant number CD18/00049), Generalitat de Catalunya (2017SGR452). Additional partial funding was received from the Gerencia Regional de Salud de Castilla y León (SACYL) (J. M. P. T., grant number GRS COVID 32/A/20).S

    Ultrahigh-energy neutrino follow-up of Gravitational Wave events GW150914 and GW151226 with the Pierre Auger Observatory

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    On September 14, 2015 the Advanced LIGO detectors observed their first gravitational-wave (GW) transient GW150914. This was followed by a second GW event observed on December 26, 2015. Both events were inferred to have arisen from the merger of black holes in binary systems. Such a system may emit neutrinos if there are magnetic fields and disk debris remaining from the formation of the two black holes. With the surface detector array of the Pierre Auger Observatory we can search for neutrinos with energy above 100 PeV from point-like sources across the sky with equatorial declination from about -65 deg. to +60 deg., and in particular from a fraction of the 90% confidence-level (CL) inferred positions in the sky of GW150914 and GW151226. A targeted search for highly-inclined extensive air showers, produced either by interactions of downward-going neutrinos of all flavors in the atmosphere or by the decays of tau leptons originating from tau-neutrino interactions in the Earth's crust (Earth-skimming neutrinos), yielded no candidates in the Auger data collected within ±500\pm 500 s around or 1 day after the coordinated universal time (UTC) of GW150914 and GW151226, as well as in the same search periods relative to the UTC time of the GW candidate event LVT151012. From the non-observation we constrain the amount of energy radiated in ultrahigh-energy neutrinos from such remarkable events.Comment: Published version. Added journal reference and DOI. Added Report Numbe

    Azimuthal asymmetry in the risetime of the surface detector signals of the Pierre Auger Observatory

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    The azimuthal asymmetry in the risetime of signals in Auger surface detector stations is a source of information on shower development. The azimuthal asymmetry is due to a combination of the longitudinal evolution of the shower and geometrical effects related to the angles of incidence of the particles into the detectors. The magnitude of the effect depends upon the zenith angle and state of development of the shower and thus provides a novel observable, (secθ)max(\sec \theta)_\mathrm{max}, sensitive to the mass composition of cosmic rays above 3×10183 \times 10^{18} eV. By comparing measurements with predictions from shower simulations, we find for both of our adopted models of hadronic physics (QGSJETII-04 and EPOS-LHC) an indication that the mean cosmic-ray mass increases slowly with energy, as has been inferred from other studies. However, the mass estimates are dependent on the shower model and on the range of distance from the shower core selected. Thus the method has uncovered further deficiencies in our understanding of shower modelling that must be resolved before the mass composition can be inferred from (secθ)max(\sec \theta)_\mathrm{max}.Comment: Replaced with published version. Added journal reference and DO

    <i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

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    Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data

    Desarrollo de productos avanzados para la misión SEOSAT/Ingenio

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    Revista oficial de la Asociación Española de Teledetección[EN] SEOSAT/Ingenio is the future Spanish Earth Observation high spatial resolution mission in the optical domain. While Level 1 products, at-sensor geo-referenced radiances, are in an advanced phase of development under the framework of an industrial contractor, Level 2 products must be developed by the users. This fact limits the use of the satellite images only to the scientific community, restricting their use in other applications. The need to alleviate this limitation motivated this work, developed under the framework of a coordinate project, which aimed at offering a list of Level2 products to the Ingenio/SEOSAT user community. In this paper, we present the different methodologies developed to produce the proposed Level2 products, from surface reflectance at nominal sensor spatial resolution to images with higher spatial resolution or the possibility to create spatial and temporal mosaics. On the one side, for the surface reflectance product, we proposed an atmospheric correction algorithm based on using the spatial information, linked to a cloud screening algorithm and including morphological and topographic shadow corrections. On the other side, to enhance the image spatial resolution, we applied different fusion techniques using the multispectral and the panchromatic band, as well as some of the so-called “super-resolution” techniques. Finally, we provided different tools to develop spatial mosaics and temporal composites, directed to users interested on the exploitation of the Ingenio/ SEOSAT images.[ES] SEOSAT/Ingenio es la futura misión española de observación de la Tierra en el óptico en alta resolución es-pacial. Mientras que los productos de imagen a Nivel 1, radiancias geo-referenciadas a nivel de sensor, se encuentran en una fase avanzada de desarrollo existiendo para ello un contrato industrial, los productos de Nivel 2 deben ser de-sarrollados por los propios usuarios. Este hecho limita el uso de las imágenes a la comunidad científica, restringiendo sus posibles aplicaciones fuera de ésta. Así pues, bajo el marco de un proyecto coordinado y motivados por ofrecer productos de Ingenio/SEOSAT de Nivel 2 a disposición de cualquier usuario, se origina y desarrolla este trabajo. En este artículo se presentan los diferentes procesos desarrollados para la elaboración de productos a Nivel 2, desde reflectividades en superficie a la resolución nominal del sensor hasta imágenes con información espacial realzada y la posibilidad de crear mosaicos espaciales y compuestos temporales. Por una parte, en el caso de los productos de reflectividad en superficie se propone una técnica de corrección atmosférica basada en el uso de la información es-pacial, previo enmascaramiento de las nubes y una exhaustiva corrección de sombras morfológicas y/o topográficas. Por otra parte, para el realce de la información espacial, han sido evaluados diferentes métodos basados en la fusión de bandas multiespectrales con una banda pancromática así como la aplicación de técnicas llamadas de “Super-re-solución”. Finalmente, se proporcionan las herramientas necesarias para la realización de mosaicos tanto espaciales como temporales para todo tipo de usuarios interesados en la explotación de las imágenesEste artículo ha sido posible gracias al proyecto coordinado “Generación de Productos de Nivel 2 para la Misión INGENIO/SEOSAT”, ESP2013- 48458-C4-1-P, subvencionado por el Ministerio de Economia y Competitividad dentro del Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia.Sabater, N.; Ruiz-Verdú, A.; Delegido, J.; Fernández-Beltrán, R.; Latorre-Carmona, P.; Pla, F.; González-Audícana, M.... (2016). Development of advanced products for the SEOSAT/Ingenio mission. Revista de Teledetección. (47):23-40. https://doi.org/10.4995/raet.2016.6569SWORD234047Blesius, L., & Weirich, F. (2005). The use of the Minnaert correction for land‐cover classification in mountainous terrain. International Journal of Remote Sensing, 26(17), 3831-3851. doi:10.1080/01431160500104194de Lussy, F., Kubik, P., Greslou, D., Pascal, V., Gigord, P., Cantou, J. P. 2005. Pleiades-HR image system products and quality. Proceedings of ISPRS Hannover Workshop 2005: High-Resolution Earth Imaging for Geospatial Information.Do, M. N., & Vetterli, M. (2005). The contourlet transform: an efficient directional multiresolution image representation. IEEE Transactions on Image Processing, 14(12), 2091-2106. doi:10.1109/tip.2005.859376Weisheng Dong, Lei Zhang, Guangming Shi, & Xiaolin Wu. (2011). Image Deblurring and Super-Resolution by Adaptive Sparse Domain Selection and Adaptive Regularization. IEEE Transactions on Image Processing, 20(7), 1838-1857. doi:10.1109/tip.2011.2108306Freedman, G., & Fattal, R. (2011). Image and video upscaling from local self-examples. ACM Transactions on Graphics, 30(2), 1-11. doi:10.1145/1944846.1944852Grodecki, J., & Dial, G. (2003). Block Adjustment of High-Resolution Satellite Images Described by Rational Polynomials. Photogrammetric Engineering & Remote Sensing, 69(1), 59-68. doi:10.14358/pers.69.1.59Liu, J. G. (2000). Smoothing Filter-based Intensity Modulation: A spectral preserve image fusion technique for improving spatial details. International Journal of Remote Sensing, 21(18), 3461-3472. doi:10.1080/014311600750037499Marini, A., Reina Barragan, F.J., Crippa, G., Harnisch, B., Fuente, I., Lopez, M., Cabeza, I., Zorita, D. 2014. SEOSAT/INGENIO – A Spanish High-spatial-resolution optical mission. International Conference on Space Optics. Tenerife, Spain, 7-10 octubre.Mekler, Y., & Kaufman, Y. J. (1982). Contrast reduction by the atmosphere and retrieval of nonuniform surface reflectance. Applied Optics, 21(2), 310. doi:10.1364/ao.21.000310Otazu, X., Gonzalez-Audicana, M., Fors, O., & Nunez, J. (2005). Introduction of sensor spectral response into image fusion methods. Application to wavelet-based methods. IEEE Transactions on Geoscience and Remote Sensing, 43(10), 2376-2385. doi:10.1109/tgrs.2005.856106Pons, X., Pesquer, L., Cristóbal, J., & González-Guerrero, O. (2014). Automatic and improved radiometric correction of Landsat imagery using reference values from MODIS surface reflectance images. International Journal of Applied Earth Observation and Geoinformation, 33, 243-254. doi:10.1016/j.jag.2014.06.002Sun, J., Xu, Z., Shum, H. Y. 2008. Image super-resolution using gradient profile prior. IEEE Conference on Computer Vision and Pattern Recognition (CVPR), 1-8.VICENTESERRANO, S., PEREZCABELLO, F., & LASANTA, T. (2008). Assessment of radiometric correction techniques in analyzing vegetation variability and change using time series of Landsat images. Remote Sensing of Environment, 112(10), 3916-3934. doi:10.1016/j.rse.2008.06.011Villa, G., Montoro, M.A. 1993. Ajuste radiométrico conjunto de varias imágenes de satélite para la realización de mosaicos de ortoimágenes. En Actas de la V Reunión Científica de la Asociación Espa-ola de Teledetección. Las Palmas de Gran Canaria, Espa-a, 10 a 12 de Noviembre, pp. 385- 394.Vivone, G., Alparone, L., Chanussot, J., Dalla Mura, M., Garzelli, A., Licciardi, G. A., … Wald, L. (2015). A Critical Comparison Among Pansharpening Algorithms. IEEE Transactions on Geoscience and Remote Sensing, 53(5), 2565-2586. doi:10.1109/tgrs.2014.2361734Wald, L., Ranchin, T., Mangolini, M. 1997. Fusion of satellite images of different spatial resolutions: Assessing the quality of resulting images. Photogrammetric Engineering & Remote Sensing, 63(6), 691-699.Zhang, Y., 2004. Understanding Image Fusion. Photogrammetric Engineering & Remote Sensing, 70(6), 657-661.Zhou, J., Civco, D. L., & Silander, J. A. (1998). A wavelet transform method to merge Landsat TM and SPOT panchromatic data. International Journal of Remote Sensing, 19(4), 743-757. doi:10.1080/01431169821597

    The Falling Incidence of Hematologic Cancer After Heart Transplantation

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    [Abstract] Background. A number of changes in the management of heart transplantation (HT) patients have each tended to reduce the risk of post-HT hematologic cancer, but little information is available concerning the overall effect on incidence in the HT population. Methods. Comparison of data from the Spanish Post-Heart-Transplantation Tumour Registry for the periods 1991–2000 and 2001–2010. Results. The incidence among patients who underwent HT in the latter period was about half that observed in the former, with a particularly marked improvement in regard to incidence more than five yr post-HT. Conclusions. Changes in HT patient management have jointly reduced the risk of hematologic cancer in the Spanish HT population. Long-term risk appears to have benefited more than short-term risk

    Lung cancer after heart transplantation: results from a large multicenter registry

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    [Abstract] In this study we analyzed Spanish Post-Heart-Transplant Tumour Registry data for adult heart transplantation (HT) patients since 1984. Median post-HT follow-up of 4357 patients was 6.7 years. Lung cancer (mainly squamous cell or adenocarcinoma) was diagnosed in 102 (14.0% of patients developing cancers) a mean 6.4 years post-HT. Incidence increased with age at HT from 149 per 100 000 person-years among under-45s to 542 among over-64s; was 4.6 times greater among men than women; and was four times greater among pre-HT smokers (2169 patients) than nonsmokers (2188). The incidence rates in age-at-diagnosis groups with more than one case were significantly greater than GLOBOCAN 2002 estimates for the general Spanish population, and comparison with published data on smoking and lung cancer in the general population suggests that this increase was not due to a greater prevalence of smokers or former smokers among HT patients. Curative surgery, performed in 21 of the 28 operable cases, increased Kaplan–Meier 2−year survival to 70% versus 16% among inoperable patients

    The Pierre Auger Observatory: Contributions to the 34th International Cosmic Ray Conference (ICRC 2015)

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    Contributions of the Pierre Auger Collaboration to the 34th International Cosmic Ray Conference, 30 July - 6 August 2015, The Hague, The NetherlandsComment: 24 proceedings, the 34th International Cosmic Ray Conference, 30 July - 6 August 2015, The Hague, The Netherlands; will appear in PoS(ICRC2015

    Chemical vapor deposition growth of boron-carbon-nitrogen layers from methylamine borane thermolysis products

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    This is the Accepted Manuscript version of an article accepted for publication in Nanotechnology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1361-6528/aa9c07This work investigates the growth of B-C-N layers by chemical vapor deposition using methylamine borane (MeAB) as the single-source precursor. MeAB has been synthesized and characterized, paying particular attention to the analysis of its thermolysis products, which are the gaseous precursors for B-C-N growth. Samples have been grown on Cu foils and transferred onto different substrates for their morphological, structural, chemical, electronic and optical characterizations. The results of these characterizations indicate a segregation of h-BN and graphene-like (Gr) domains. However, there is an important presence of B and N interactions with C at the Gr borders, and of C interacting at the h-BN-edges, respectively, in the obtained nano-layers. In particular, there is a significant presence of C-N bonds, at Gr/h-BN borders and in the form of N doping of Gr domains. The overall B:C:N contents in the layers is close to 1:3:1.5. A careful analysis of the optical bandgap determination of the obtained B-C-N layers is presented, discussed and compared with previous seminal works with samples of similar compositio
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