303 research outputs found

    Temperature and magnetic-field dependence of the conductivity of YBaCuO films in the vicinity of superconducting transition: Effect of Tc-inhomogeneity

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    Temperature and magnetic field dependences of the conductivity of YBaCuO films in the transition region are analyzed taking into account spatial inhomogeneity in transition temperature, Tc. (i) An expression for the superconducting contribution to conductivity, \sigma_s(T,H,Tc), of a homogeneous superconductor for H<<Hc2(T=0) is obtained using the solution of the Ginzburg-Landau equation in form of perturbation expansions [S.Ullah, A.T.Dorsey, PRB 44, 262 (1991)]. (ii) The error in \sigma_s(T,H,Tc) occurring due to the presence of Tc-inhomogeneity is calculated and plotted on an H-T plane diagram. These calculations use an effective medium approximation and a Gaussian distribution of Tc. (iii) Measuring the temperature dependences of a voltage, induced by a focused electron beam, we determine spatial distributions of the critical temperature for YBaCuO microbridges with a 2 micron resolution. A typical Tc-distribution dispersion is found to be approximately 1K. For such dispersion, error in \sigma_s(T,H,Tc) due to Tc-inhomogeneity exceeds 30% for magnetic fields H < 1 T and temperatures |T-Tc| < 0.5 K. (iv) Experimental R(T,H) dependences of resistance are well described by a numerical solution of a set of Kirchoff equations for the resistor network based on the measured spatial distributions of Tc and the expression for \sigma_s(T,H,Tc).Comment: REVTeX, 12 pages including 7 figures, resubmitted to Phys. Rev.

    Assessment of fetal corpus callosum biometry by 3D super-resolution reconstructed T2-weighted magnetic resonance imaging.

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    To assess the accuracy of corpus callosum (CC) biometry, including sub-segments, using 3D super-resolution fetal brain MRI (SR) compared to 2D or 3D ultrasound (US) and clinical low-resolution T2-weighted MRI (T2WS). Fetal brain biometry was conducted by two observers on 57 subjects [21-35 weeks of gestational age (GA)], including 11 cases of partial CC agenesis. Measures were performed by a junior observer (obs1) on US, T2WS and SR and by a senior neuroradiologist (obs2) on T2WS and SR. CC biometric regression with GA was established. Statistical analysis assessed agreement within and between modalities and observers. This study shows robust SR to US concordance across gestation, surpassing T2WS. In obs1, SR aligns with US, except for genu and CC length (CCL), enhancing splenium visibility. In obs2, SR closely corresponds to US, differing in rostrum and CCL. The anterior CC (rostrum and genu) exhibits higher variability. SR's regression aligns better with literature (US) for CCL, splenium and body than T2WS. SR is the method with the least missing values. SR yields CC biometry akin to US (excluding anterior CC). Thanks to superior 3D visualization and better through plane spatial resolution, SR allows to perform CC biometry more frequently than T2WS

    Vaccine Willingness and Impact of the COVID-19 Pandemic on Women's Perinatal Experiences and Practices-A Multinational, Cross-Sectional Study Covering the First Wave of the Pandemic.

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    The COVID-19 pandemic may be of particular concern for pregnant and breastfeeding women. We aimed to explore their beliefs about the coronavirus and COVID-19 vaccine willingness and to assess the impact of the pandemic on perinatal experiences and practices. A multinational, cross-sectional, web-based study was performed in six European countries between April and July 2020. The anonymous survey was promoted via social media. In total, 16,063 women participated (including 6661 pregnant and 9402 breastfeeding women). Most responses were collected from Belgium (44%), Norway (18%) and the Netherlands (16%), followed by Switzerland (11%), Ireland (10%) and the UK (3%). Despite differences between countries, COVID-19 vaccine hesitancy was identified among 40-50% of the respondents at the end of the first wave of the pandemic and was higher among pregnant women. Education level and employment status were associated with vaccine hesitancy. The first wave had an adverse impact on pregnancy experiences and disrupted access to health services and breastfeeding support for many women. In the future, access to health care and support should be maintained at all times. Evidence-based and tailored information on COVID-19 vaccines should also be provided to pregnant and breastfeeding women to avoid unfounded concerns about the vaccines and to support shared decision making in this population

    Impact of the COVID-19 pandemic on Swiss pregnant and breastfeeding women - a cross-sectional study covering the first pandemic wave.

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    Information on the impact of the COVID-19 pandemic on pregnancy and breastfeeding experiences, as well as on perinatal mental health in Switzerland is limited. In Switzerland, there are few national studies and little information. Using an anonymous online survey accessible after the first wave of the outbreak in Switzerland, we have investigated how this pandemic affected pregnant and breastfeeding women. Among women who completed the survey, 69.0% (1050/1518) indicated the first wave of the pandemic affected their personal habits, 61.0% (689/1131) were affected in their work and 40.0% (632/1573) reported impaired relations with healthcare services (different denominators correspond to the number of participants who answered the question). 36.8% (110/299) of women reported an impact of the pandemic on their current pregnancy experience or breastfeeding experience (8.2%, 46/555). Overall, 11.6% (170/1467) of participants who completed the validated screening tests for mental health symptoms (Edinburgh Postnatal Depression Scale, Generalized Anxiety Disorder 7, Perceived Stress Scale) presented a score compatible with symptoms of major depression, severe anxiety or high perceived stress, which is higher than in the pre-pandemic period according to literature. Risk factors independently associated with impaired mental health were being hospitalized, having symptoms of COVID-19, living with a person with COVID-19 symptoms, having comorbidities, having experienced reduced healthcare services, having restricted usual activities and being a housewife. Protective factors independently associated were a high level of education and living with a partner. Our findings suggest that the COVID-19 pandemic might have significantly affected the well-being and mental health of pregnant and breastfeeding women, directly in the case of exposure, and indirectly as a result of the potential modifications in their life habits and in healthcare facilities

    Potential and current distribution in strongly anisotropic Bi(2)Sr(2) CaCu(2)O(8) single crystals at current breakdown

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    Experiments on potential differences in the low-temperature vortex solid phase of monocrystalline platelets of superconducting Bi(2)Sr(2)CaCu(2)O(8) (BSCCO) subjected to currents driven either through an "ab" surface or from one such surface to another show evidence of a resistive/nonresistive front moving progressively out from the current contacts as the current increases. The depth of the resistive region has been measured by a novel in-depth voltage probe contact. The position of the front associated with an injection point appears to depend only on the current magnitude and not on its withdrawal point. It is argued that enhanced nonresistive superconducting anisotropy limits current penetration to less than the London length and results in a flat rectangular resistive region with simultaneous "ab" and "c" current breakdown which moves progressively out from the injection point with increasing current. Measurements in "ab" or "c" configurations are seen to give the same information, involving both ab-plane and c-axis conduction properties.Comment: 9 pages, 13 figures, typo error corrected, last section was refine

    Critical scaling of the a.c. conductivity for a superconductor above Tc

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    We consider the effects of critical superconducting fluctuations on the scaling of the linear a.c. conductivity, \sigma(\omega), of a bulk superconductor slightly above Tc in zero applied magnetic field. The dynamic renormalization- group method is applied to the relaxational time-dependent Ginzburg-Landau model of superconductivity, with \sigma(\omega) calculated via the Kubo formula to O(\epsilon^{2}) in the \epsilon = 4 - d expansion. The critical dynamics are governed by the relaxational XY-model renormalization-group fixed point. The scaling hypothesis \sigma(\omega) \sim \xi^{2-d+z} S(\omega \xi^{z}) proposed by Fisher, Fisher and Huse is explicitly verified, with the dynamic exponent z \approx 2.015, the value expected for the d=3 relaxational XY-model. The universal scaling function S(y) is computed and shown to deviate only slightly from its Gaussian form, calculated earlier. The present theory is compared with experimental measurements of the a.c. conductivity of YBCO near Tc, and the implications of this theory for such experiments is discussed.Comment: 16 pages, submitted to Phys. Rev.

    Genómica y embriología de Dalbulus maidis (Delong & Wolcott, 1923). (Hemiptera-auchenorrhyncha): nuevos conocimientos para nuevas herramientas de control

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    Hemos generado información genómica aplicable a nuevos métodos de control de la plaga de maíz, Dalbulus maidis (De Long &amp;amp; Wolcott, 1923; Hemíptera, Cicadellidae) vector de Spiroplasma kunkelii, patógeno causante del achaparramiento del maíz. Realizamos el análisis preliminar del transcriptoma y estudiamos los procesos embriológicos del vector con el fin de generar métodos del silenciamiento de genes esenciales para el desarrollo, la fertilidad y la supervivencia

    Anatomy and origin of authochthonous late Pleistocene forced regression deposits, east Coromandel inner shelf, New Zealand: implications for the development and definition of the regressive systems tract

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    High-resolution seismic reflection data from the east Coromandel coast, New Zealand, provide details of the sequence stratigraphy beneath an autochthonous, wave dominated inner shelf margin during the late Quaternary (0-140 ka). Since c. 1 Ma, the shelf has experienced limited subsidence and fluvial sediment input, producing a depositional regime characterised by extensive reworking of coastal and shelf sediments during glacio-eustatic sea-level fluctuations. It appears that only one complete fifth-order (c. 100 000 yr) depositional sequence is preserved beneath the inner shelf, the late Pleistocene Waihi Sequence, suggesting any earlier Quaternary sequences were mainly cannibalised into successively younger sequences. The predominantly Holocene-age Whangamata Sequence is also evident in seismic data and modern coastal deposits, and represents an incomplete depositional sequence in its early stages of formation. A prominent aspect of the sequence stratigraphy off parts of the east Coromandel coast is the presence of forced regressive deposits (FRDs) within the regressive systems tract (RST) of the late Pleistocene Waihi Sequence. The FRDs are interpreted to represent regressive barrier-shoreface sands that were sourced from erosion and onshore reworking of underlying Pleistocene sediments during the period of slow falling sea level from isotope stages 5 to 2 (c. 112-18 ka). The RST is volumetrically the most significant depositional component of the Waihi Sequence; the regressive deposits form a 15-20 m thick, sharp-based, tabular seismic unit that downsteps and progrades continuously across the inner shelf. The sequence boundary for the Waihi Sequence is placed at the most prominent, regionally correlative, and chronostratigraphically significant surface, namely an erosional unconformity characterised in many areas by large incised valleys that was generated above the RST. This unconformity is interpreted as a surface of maximum subaerial erosion generated during the last glacial lowstand (c. 18 ka). Although the base of the RST is associated with a prominent regressive surface of erosion, this is not used as the sequence boundary as it is highly diachronous and difficult to identify and correlate where FRDs are not developed. The previous highstand deposits are limited to subaerial barrier deposits preserved behind several modern Holocene barriers along the coast, while the transgressive systems tract is preserved locally as incised-valley fill deposits beneath the regressive surface of erosion at the base of the RST. Many documented late Pleistocene RSTs have been actively sourced from fluvial systems feeding the shelf and building basinward-thickening, often stacked wedges of FRDs, for which the name allochthonous FRDs is suggested. The Waihi Sequence RST is unusual in that it appears to have been sourced predominantly from reworking of underlying shelf sediments, and thus represents an autochthonous FRD. Autochthonous FRDs are also present on the Forster-Tuncurry shelf in southeast Australia, and may be a common feature in other shelf settings with low subsidence and low sediment supply rates, provided shelf gradients are not too steep, and an underlying source of unconsolidated shelf sediments is available to source FRDs. The preservation potential of such autochthonous FRDs in ancient deposits is probably low given that they are likely to be cannibalised during subsequent sea-level falls

    CORECLUST: identification of the conserved CRM grammar together with prediction of gene regulation

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    Identification of transcriptional regulatory regions and tracing their internal organization are important for understanding the eukaryotic cell machinery. Cis-regulatory modules (CRMs) of higher eukaryotes are believed to possess a regulatory ‘grammar’, or preferred arrangement of binding sites, that is crucial for proper regulation and thus tends to be evolutionarily conserved. Here, we present a method CORECLUST (COnservative REgulatory CLUster STructure) that predicts CRMs based on a set of positional weight matrices. Given regulatory regions of orthologous and/or co-regulated genes, CORECLUST constructs a CRM model by revealing the conserved rules that describe the relative location of binding sites. The constructed model may be consequently used for the genome-wide prediction of similar CRMs, and thus detection of co-regulated genes, and for the investigation of the regulatory grammar of the system. Compared with related methods, CORECLUST shows better performance at identification of CRMs conferring muscle-specific gene expression in vertebrates and early-developmental CRMs in Drosophila

    Informe del seguimiento científico de la acción piloto RAI/AP-26/2007: Pesca experimental con arte de arrastre de fondo en el Golfo de León (Mediteráneo noroccidental)

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    RESUMEN.- Del 24 de Octubre al 18 de Diciembre de 2007, se han realizado 67 pescas experimentales de arrastre de fondo, a bordo de las embarcaciones B/P Berto y B/P Sort de Taranet, en caladeros del talud del Golfo de León, situados en aguas internacionales al este del Cabo Creus y alejados entre 70 y 100 millas de su puerto base (Port de la Selva). Ambos barcos trabajaron de manera continuada durante 46 horas semanales (su período de actividad habitual es de 5 días semanales y 12 ó 16 horas diarias), utilizando una red de arrastre tipo cuadrado-dragón, que habitualmente usan para sus operaciones de pesca comercial en el área. De manera simultánea, un barco utilizó el copo tradicional de malla rómbica de 40 mm, mientras que el otro utilizó un copo de malla cuadrada de 40 mm. Ello permitió comparar la selectividad de ambos copos por el método de pescas paralelas. Del total de pescas, 50 fueron consideradas válidas para el análisis de datos, en base a dos estratos batimétricos: (i) 300-450 m, dirigidas a cigala (B/P Berto: 14 pescas entre 357 y 434 m; B/P Sort de Taranet: 14 pescas entre 371 y 451 m); (ii) 450-700 m, dirigidas a gamba roja (B/P Berto: 11 pescas entre 478 y 692 m; B/P Sort de Taranet: 11 pescas entre 493 y 571 m). Se han estimado los rendimientos medios, estandarizados a hora de arrastre efectivo, su fracción comercial y descartada y la distribución de tallas de las principales especies de interés comercial y ecológico. Paralelamente, se ha recogido información de los desembarcos y consumo de combustible esta acción piloto y para el mismo período de 2006, en que estas embarcaciones realizaron su actividad pesquera rutinaria. El análisis de esta información se ha realizado mediante técnicas uni- y multi-variantes. Los elevados rendimientos, así como la distribución de tallas de la captura de las principales especies explotadas, indican que los fondos prospectados están poco explotados. En ambos estratos batimétricos, con la malla cuadrada se redujeron los descartes, sin una disminución significativa de los rendimientos comerciales. Del mismo modo, la estrategia de pesca aplicada durante la acción piloto redujo el esfuerzo efectivo de pesca, sin disminuir el rendimiento de la pesquería respecto del mismo período de 2006. Además, se redujo considerablemente el consumo de combustible, lo que repercutió positivamente en las tasas de combustible consumido por unidad de desembarcos. La estrategia de explotación aplicada en la acción piloto mejora la relación coste-eficiencia de la pesquería y presenta una serie de ventajas, tanto de mejora en el rendimiento pesquero y en la explotación de los recursos, como de carácter medioambiental y social. No obstante, aplicar esta estrategia a la explotación comercial conlleva riesgos para el mantenimiento de los stocks de especies explotadas y la conservación de hábitats de especial interés y ecosistemas marinos vulnerables, en un área con numerosos cañones submarinos, como el Golfo de León.RESUM.- INFORME DEL SEGUIMENT CIENTÍFIC DE L’ACCIÓ PILOT RAI/AP-26/2007: PESCA EXPERIMENTAL AMB ART DE RÒSSEC DE FONS EN EL GOLF DE LLEÓ (MEDITERRÀNIA NOR-OCCIDENTAL): Del 24 de Octubre al 18 de Desembre de 2007, s’han dut a terme 67 pesques experimentals de ròssec de fons, a bord de les embarcacions B/P Berto i B/P Sort de Taranet, en caladors del talús del Golf de Lleó, situats en aigües internacionals a l’est del Cap de Creus, allunyats entre 70 i 100 milles del seu port base (Port de la Selva). Ambdós vaixells van treballar de manera continuada durant 46 hores setmanals (el seu període d’activitat habitual és de 5 dies setmanals i 12 ó 16 hores diàries), utilitzant una xarxa de ròssec de tipus quadratdragó, que habitualment utilitzen per les operacions de pesca comercial a l’àrea. De manera simultània, un vaixell va emprar el cóp tradicional de malla ròmbica de 40 mm, mentre que l’altre va emprar un cóp de malla quadrada de 40 mm. Això va permetre comparar la selectivitat d’ambdós cóps, mitjançant el mètode de pesques paral·leles. Del total de pesques, 50 foren considerades vàlides per l’anàlisi de dades, en base a dos estrats batimètrics: (i) 300-450 m, dirigides a escamerlà (B/P Berto: 14 pesques entre 357 i 434 m; B/P Sort de Taranet: 14 pesques entre 371 i 451 m); (ii) 450-700 m, dirigides a gamba vermella (B/P Berto: 11 pesques entre 478 i 692 m; B/P Sort de Taranet: 11 pesques entre 493 i 571 m). S’han estimat els rendiments mitjans, estandarditzats a hora efectiva de ròssec, la seva fracció comercial i rebutjada i la distribució de talles de les principals espècies d’interès comercial i ecològic. Paral·lelament, s’ha recollit informació dels desembarcaments i consum de combustible durant l’acció pilot de 2007 i pel mateix període de 2006, en que aquestes embarcacions van realitzar la seva activitat pesquera rutinària. L’anàlisi d’aquesta informació s’ha realitzat mitjançant tècniques uni- i multi-variants. Els elevats rendiments, així com la distribució de talles de la captura de les principals espècies explotades, indiquen que els fons prospectats estan poc explotats. En ambdós estrats batimètrics, amb la malla quadrada es van reduir els rebuigs, sense una disminució significativa dels rendiments comercials. De manera semblant, l’estratègia de pesca aplicada durant l’acció pilot va reduir l’esforç efectiu de pesca, sense disminuir el rendiment de la pesquera respecte del mateix període de 2006. A més, es va reduir considerablement el consum de combustible, la qual cosa va repercutir positivament en les tases de combustible consumit per unitat de desembarcaments. L’estratègia d’explotació aplicada en l’acció pilot incrementa la relació cost-eficiència de la pesquera i presenta una sèrie d’avantatges, tant de millora en el rendiment pesquer i en l’explotació dels recursos, com de caràcter mediambiental i social. No obstant, aplicar aquesta estratègia a l’explotació comercial comporta riscs pel manteniment dels estocs d’espècies explotades i la conservació d’hàbitats d’especial interès i ecosistemes marins vulnerables, a una àrea amb nombrosos canons submarins, com el Golf de Lleó.Secretaria General de Pesca Marítim
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