669 research outputs found

    A Large Brightness Enhancement of the QSO 0957+561 A Component

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    We report an increase of more than 0.2 mag in the optical brightness of the leading image (A) of the gravitational lens Q0957+561, detected during the 09/2000 -- 06/2001 monitoring campaign (2001 observing season). The brightening is similar to or even greater than the largest change ever detected during the 20 years of monitoring of this system. We discuss two different provisional explanations to this event: intrinsic source variability or microlensing (either short timescale microlensing or cessation of the historical microlensing). An exhaustive photometric monitoring of Q0957+561 is needed until summer of 2002 and during 2003 to discriminate between these possibilities.Comment: 13 pages including 3 figures and 1 table. Accepted for publication in ApJ Let

    Caracterización de la Falla de Alhama de Murcia mediante MASW

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    The deep structure of the Alhama de Murcia Fault (AMF) is characterized by means of the analysis of surface waves identified in shallow high resolution seismic reflection data. Multichannel analysis of surface waves (MASW) is used to unravel the 2-D S-wave velocity model and image the depth geometry of the fault system. The study area includes segments of the fault located in La Salud area. Two approaches have been used to achieve a well constrained velocity model in the AMF fault zone. Conventional seismic reflection processing work flow has been used to clean the seismic data and increase its S/N ratio. Occam’s approach has been used to invert the digitized surface wave dispersion curves. 1D shear wave velocity-depth profiles were estimated in shot and CDP domains. Relatively well resolved 2D velocity-depth models were obtained by com- posite of the 1D Velocity-depth functions. These composite 2D-velocity models are able to constrain the depth geometry of the fault zone up to 100 m depth. The fault zone is indicated by a relatively broad low velocity anomaly that correlates with the fault’s surface expression.La estructura profunda de la falla de Alhama de Murcia (AMF) ha sido caracterizada mediante el análisis de ondas superficiales identificados en datos de reflexión sísmica superficial de alta resolución. El análisis multicanal de ondas de superficie (MASW) es usado para desentrañar un modelo 2D de Vs y para obtener imágenes de la geometría del sistema de fallas en profundidad. El área de estudio incluye segmentos de la AMF ubicados en el área de La Salud. Se han utilizado dos enfoques para lograr modelos de velocidad bien restringidos de la zona de falla. Por un lado, se han limpiado los datos utilizado un flujo de procesado convencional diseñado para aumentar su ratio de señal/ruido. Por el otro, se ha usado el enfoque de Occam para invertir las curvas de dispersión de ondas de superficie digitalizadas. Los perfiles 1D de profundidad de las Vs fueron estimados en los dominios de disparo y de CDP. Se obtuvieron modelos de velocidad-profundidad 2D relativamente bien resueltos mediante la interpolación de las funciones de velocidad-profundidad 1D. Estos modelos de velocidad 2D ayu- dan a restringir en profundidad la geometría de la zona de falla hasta los 100 m que se caracteriza por una anomalía de baja velocidad relativamente amplia que se correlaciona en la superficie con la expresión de la falla.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEMinisterio de Ciencia e Innovación (MICINN)ICTJA-CSICMinistry of Education and Culture of the Republic of Indonesiapu

    Distribución y estado de conservación de los quirópteros en Aragón

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    In the period 2004-2006 a sampling of bats took place in Aragón. Traps were set in 47 forests and 67 potential shelters were inspected. Mist nets, harp traps, ultrasound detectors and video cameras were used. A total of 1197 specimens, belonging to 24 species, were captured; 529 records were obtained and the presence of at least 120 breeding colonies was identified (32 of them the common pipistrelle (Pipistrellus pipistrellus, 110 records and 30 breeding colonies), Savi’s pipistrelle (Hypsugo savii, 63 records and 11 colonies) and Kuhl’s pipistrelle (Pipistrellus kuhlii, 48 records and 13 colonies). Reproduction data have been found for all species except for Myotis capaccinii, Myotis cf. nattereri, Nyctalus lasiopterus, Nyctalus leisleri and Eptesicus serotinus. The species found can be divided into four large groups: one of general and continuous distribution (P. pipistrellus, P. kuhlii, H. savii, E. serotinus and P. austriacus), another of general but discontinuous distribution (R. ferrumequinum, R. hipposideros, R. euryale, M. myotis, M. blythii, M. escalerae, M. emarginatus, M. daubentonii, P. pygmaeus, M. schreibersii and T. teniotis), a third of forest species, which were found only in some of the extensive wooded areas (Pyrenees, Moncayo and the south of Teruel: M. mystacinus, M. cf. nattereri, P. auritus, B. barbastellus, N. lasiopterus and N. leisleri) and finally two very rare species in the region (M. capaccinii and P. macrobullaris). The distribution of these species in Aragon is shown and their status in relation to data obtained and the bibliography is reviewed.En el período 2004-2006 se ha realizado un muestreo de los quirópteros de Aragón. Se ha trampeado en 47 bosques y se han inspeccionado 67 refugios potenciales. Para ello se han utilizado redes finas, trampas de arpa, detectores de ultrasonidos, focos y cámaras de grabación de vídeo. Se han capturado 1197 ejemplares pertenecientes a 24 especies. Además se han obtenido 529 citas y se ha identificado la presencia de al menos 120 colonias reproductoras (32 de ellas han sido localizadas). Las especies más frecuentes son fisurícolas y ubiquistas: el murciélago enano (Pipistrellus pipistrellus, 110 citas y 30 colonias de cría), el montañero (Hypsugo savii, 63 citas y 11 agrupaciones) y el de borde claro (Pipistrellus kuhlii, 48 citas y 13 colonias). Se han encontrado datos de reproducción para todas las especies identificadas salvo Myotis capaccinii, Myotis cf. nattereri, Nyctalus lasiopterus, Nyctalus leisleri y Eptesicus serotinus. Las especies halladas se reparten según cuatro patrones: uno de distribución general y continua (P. pipistrellus, P. kuhlii, H. savii, E. serotinus y P. austriacus), otro de distribución general pero discontinua (R. ferrumequinum, R. hipposideros, R. euryale, M. myotis, M. blythii, M. escalerae, M. emarginatus, M. daubentonii, P. pygmaeus, M. schreibersii y T. teniotis), otro de especies forestales, presentes únicamente en algunas de las grandes manchas boscosas (Pirineos, Moncayo y sur de Teruel: M. mystacinus, M. cf. nattereri, P. auritus, B. barbastellus, N. lasiopterus y N. leisleri) y el último con dos especies de presencia muy restringida en la región (M. capaccinii y P. macrobullaris). Se muestra la distribución de estas especies en Aragón y se comenta su estado de conservación en función de los datos obtenidos en este trabajo y la bibliografí

    Vigilancia de Parálisis Flácida Aguda. España 2008.

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    An Impossibility Theorem in Matching Problems

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    This paper studies the possibility of strategy-proof rules yielding satisfactory solutions to matching problems. Alcalde and Barberá (1994) show that effcient and individually rational matching rules are manipulable in the one-to-one matching model. We pursue the possibility of strategy-proof matching rules by relaxing effciency to the weaker condition of respect for unanimity. Our first result is positive. We prove that a strategy-proof rule exists that is individually rational and respects unanimity. However, this rule is unreasonable in the sense that a pair of agents who are the best for each other are matched on only rare occasions. In order to explore the possibility of better matching rules, we introduce the natural condition of 'respect for pairwise unanimity.' Respect for pairwise unanimity states that a pair of agents who are the best for each other should be matched, and an agent wishing to stay single should stay single. Our second result is negative. We prove that no strategy-proof rule exists that respects pairwise unanimity. This result implies Roth (1982) showing that stable rules are manipulable. We then extend this to the many-to-one matching model

    An intuitionistic approach to scoring DNA sequences against transcription factor binding site motifs

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    Background: Transcription factors (TFs) control transcription by binding to specific regions of DNA called transcription factor binding sites (TFBSs). The identification of TFBSs is a crucial problem in computational biology and includes the subtask of predicting the location of known TFBS motifs in a given DNA sequence. It has previously been shown that, when scoring matches to known TFBS motifs, interdependencies between positions within a motif should be taken into account. However, this remains a challenging task owing to the fact that sequences similar to those of known TFBSs can occur by chance with a relatively high frequency. Here we present a new method for matching sequences to TFBS motifs based on intuitionistic fuzzy sets (IFS) theory, an approach that has been shown to be particularly appropriate for tackling problems that embody a high degree of uncertainty. Results: We propose SCintuit, a new scoring method for measuring sequence-motif affinity based on IFS theory. Unlike existing methods that consider dependencies between positions, SCintuit is designed to prevent overestimation of less conserved positions of TFBSs. For a given pair of bases, SCintuit is computed not only as a function of their combined probability of occurrence, but also taking into account the individual importance of each single base at its corresponding position. We used SCintuit to identify known TFBSs in DNA sequences. Our method provides excellent results when dealing with both synthetic and real data, outperforming the sensitivity and the specificity of two existing methods in all the experiments we performed. Conclusions: The results show that SCintuit improves the prediction quality for TFs of the existing approaches without compromising sensitivity. In addition, we show how SCintuit can be successfully applied to real research problems. In this study the reliability of the IFS theory for motif discovery tasks is proven

    Characterization of the shallow subsurface structure across the Carrascoy Fault System (SE Iberian Peninsula) using P-wave tomography and Multichannel Analysis of Surface Waves

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    The seismicity in the SE Iberian Peninsula is distributed parallel to the coast in a well-developed strike-slip fracture system known as the Eastern Betic Shear Zone (EBSZ). This work focuses on the characterization of the shallow subsurface structure of the Algezares-Casas Nuevas Fault, within the Carrascoy Fault System of the EBSZ. The Carrascoy Fault borders the Guadalentín Depression to the south, which is a densely populated area with extensive agricultural activity. Therefore, this faults system represents a seismic hazard with significant social and economic implications. We have constructed two velocity-depth models based on P-wave tomography and Multichannel Analysis of Surface Waves (MASW) acquired from seismic reflection data. The resulting velocity models have allowed us to interpret the first ~250m depth and have revealed: i) the thickness of the critical zone; ii) the geometry of the Algezares-Casas Nuevas Fault; iii) the depth of the Messinian/Tortonian contact and iv) the presence of blind thrusts and damage zones under the Guadalentín Depression. Our results have also helped us to estimate an apparent vertical slip rate of 0.66±0.06m/ky for the Algezares-Casas Nuevas Fault since 209.1±6.2ka. Our results provide a methodological and backflow protocol to study the shallow subsurface of active faults, complementing previous geological models based on paleoseismological trenches, and can be used to improve the seismic hazard assessment of tectonically active regions around the world.The authors would like to acknowledge the project INTERGEO (CGL2013-47412-C2-1-P) GEO3BCNCSIC for the data access. Data are public access through SeisDARE (DeFelipe et al., 2021), dataset Martí et al. (2015). The Ministry of Education and Culture of the Republic of Indonesia is thanked for the main author’s Ph.D. scholarship (D3.2/KD.02.01/2019). JA is funded by MICINN (IJC2018-026335-I). I.P. is funded by the Spanish Government and the Universidad de Salamanca (Beatriz Galindo grant BEGAL 18/00090). IDF is funded by a FEDER-Junta de Castilla y León Postdoctoral contract (SA0084P20). We thank the GIPP-GFZ, (Germany) and Lisbon University (Portugal) for the instrumentation provided. Generalitat de Catalunya (AGAUR) grant 2017SGR1022 (GREG); EU (H2020) 871121 (EPOSSP); and EIT-RawMaterias 17024 (SIT4ME). WPeer reviewe

    DFT calculation of the intermolecular exchange interaction in the magnetic Mn4_4 dimer

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    The dimeric form of the single-molecule magnet [Mn4_4O3_3Cl4_4(O2_2CEt)3_3(py)3_3]2_2 recently revealed interesting phenomena: no quantum tunneling at zero field and tunneling before magnetic field reversal. This is attributed to substantial antiferromagnetic exchange interaction between different monomers. The intermolecular exchange interaction, electronic structure and magnetic properties of this molecular magnet are calculated using density-functional theory within generalized-gradient approximation. Calculations are in good agreement with experiment.Comment: 4 page

    Characterization of the shallow subsurface structure across the Carrascoy Fault System (SE Iberian Peninsula) using P-wave tomography and Multichannel Analysis of Surface Waves

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    The seismicity in the SE Iberian Peninsula is distributed parallel to the coast in a well-developed strike-slip fracture system known as the Eastern Betic Shear Zone (EBSZ). This work focuses on the characterization of the shallow subsurface structure of the Algezares-Casas Nuevas Fault, within the Carrascoy Fault System of the EBSZ. The Carrascoy Fault borders the Guadalentín Depression to the south, which is a densely populated area with extensive agricultural activity. Therefore, this faults system represents a seismic hazard with significant social and economic implications. We have constructed two velocity-depth models based on P-wave tomography and Multichannel Analysis of Surface Waves (MASW) acquired from seismic reflection data. The resulting velocity models have allowed us to interpret the first ~250m depth and have revealed: i) the thickness of the critical zone; ii) the geometry of the Algezares-Casas Nuevas Fault; iii) the depth of the Messinian/Tortonian contact and iv) the presence of blind thrusts and damage zones under the Guadalentín Depression. Our results have also helped us to estimate an apparent vertical slip rate of 0.66±0.06m/ky for the Algezares-Casas Nuevas Fault since 209.1±6.2ka. Our results provide a methodological and backflow protocol to study the shallow subsurface of active faults, complementing previous geological models based on paleoseismological trenches, and can be used to improve the seismic hazard assessment of tectonically active regions around the world
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