247 research outputs found
Linking changes in radial profiles of sap flux density with the response of water vapour exchange to water deficit
8 páginas, 5 figuras, 1 tabla, 19 referencias.-- IX International Workshop on Sap Flow, celebrado del 4-7 de junio 2013, en Gante, Bélgica.Knowledge of temporal variations in radial profiles of sap flux density (Js) and its relation to canopy water vapour exchange would help to improve our understanding of plant water relations. In this study we aimed to test if there is a consistent radial profile of Js in olive trees under optimal soil water availability and severe water stress conditions. Furthermore, if the radial profile of Js is not consistent through time we aimed to assess whether this radial variability can be explained through differential water exchange response to evaporative demand (D) of sun-exposed, new foliage and shade, old foliage. We measured sap flux density in the trunk of 6-year-old olive trees under two different irrigation treatments: a full irrigation treatment and a treatment replacing 30% of the of irrigation needs. We related the hourly radial profiles characterized with the Beta probability distribution function with independent water vapour exchange measurements at different exposures in the tree canopy (sun-exposed, young foliage and shade, old foliage). Results showed that under well irrigated conditions the shape of the radial profile of Js hardly varied, but under water deficit situations most of the sap appears to be conducted deeper into the sapwood and Js is also more variable throughout the sapwood. Accordingly, results demonstrated that in shade, old foliage water vapour exchange varied less than in sun-exposed new foliage. As a result, in days under severe water deficit, the contribution of shade old foliage to the whole tree transpiration was greater. Radial profile changes and canopy measurements were found to respond in a similar way to D. During conditions of low D and soil water deficit it was observed a greater contribution of the inner xylem to total stem flow and shade, old leaves to canopy gas exchange.Peer reviewe
Melting and transverse depinning of driven vortex lattices in the periodic pinning of Josephson junction arrays
We study the non-equilibrium dynamical regimes of a moving vortex lattice in
the periodic pinning of a Josephson junction array (JJA) for {\it finite
temperatures} in the case of a fractional or submatching field. We obtain a
phase diagram for the current driven JJA as a function of the driving current I
and temperature T. We find that when the vortex lattice is driven by a current,
the depinning transition at and the melting transition at
become separated even for a field for which they coincide in equilibrium. We
also distinguish between the depinning of the vortex lattice in the direction
of the current drive, and the {\it transverse depinning} in the direction
perpendicular to the drive. The transverse depinning corresponds to the onset
of transverse resistance in a moving vortex lattice at a given temperature
. For driving currents above the critical current we find that the
moving vortex lattice has first a transverse depinning transition at low T, and
later a melting transition at a higher temperature, .Comment: 17 pages, 19 figure
Influencia del shot peening sobre la vida en ensayos de fatiga por fretting con contacto cilíndrico
En este trabajo se caracteriza la aleación de AL7075-T651 ante la fatiga por fretting. En concreto se estudia la influencia
sobre la vida a fatiga por fretting del coeficiente de rozamiento, la rugosidad superficial y las tensiones residuales
introducidas por un tratamiento de shot-peening. Este tratamiento, además de introducir tensiones residuales de
compresión en el material, también modifica la rugosidad superficial debida a la deformación plástica producida por el
tratamiento. De las probetas ensayadas, un grupo no ha sido tratado superficialmente. Otro grupo de probetas están
tratadas con shot-peening para su comparación con ensayos con las mismas cargas aplicadas. En otro grupo de probetas
se induce la rugosidad superficial que causa el tratamiento pero sin la deformación plástica y la consecuente tensión
residual de compresión. En un último grupo de probetas tratadas con shot peening se altera la rugosidad superficial sin
modificar la tensión residual de compresión. Para analizar cómo afectan a la vida en ensayos de fatiga por fretting las
diferentes modificaciones producidas por el shot peening, se ha medido la rugosidad superficial, coeficiente de rozamiento
y tensiones residuales para correlacionarlas con la vida a fatiga y lugar de iniciación de las grietas.Junta de Andalucía P12-TEP-263
Transverse Phase Locking for Vortex Motion in Square and Triangular Pinning Arrays
We analyze transverse phase locking for vortex motion in a superconductor
with a longitudinal DC drive and a transverse AC drive. For both square and
triangular arrays we observe a variety of fractional phase locking steps in the
velocity versus DC drive which correspond to stable vortex orbits. The locking
steps are more pronounced for the triangular arrays which is due to the fact
that the vortex motion has a periodic transverse velocity component even for
zero transverse AC drive. All the steps increase monotonically in width with AC
amplitude. We confirm that the width of some fractional steps in the square
arrays scales as the square of the AC driving amplitude. In addition we
demonstrate scaling in the velocity versus applied DC driving curves at
depinning and on the main step, similar to that seen for phase locking in
charge-density wave systems. The phase locking steps are most prominent for
commensurate vortex fillings where the interstitial vortices form symmetrical
ground states. For increasing temperature, the fractional steps are washed out
very quickly, while the main step gains a linear component and disappears at
melting. For triangular pinning arrays we again observe transverse phase
locking, with the main and several of the fractional step widths scaling
linearly with AC amplitude.Comment: 10 pages, 14 postscript figure
Orientational pinning and transverse voltage: Simulations and experiments in square Josephson junction arrays
We study the dependence of the transport properties of square Josephson
Junctions arrays with the direction of the applied dc current, both
experimentally and numerically. We present computational simulations of
current-voltage curves at finite temperatures for a single vortex in the array
(), and experimental measurements in
arrays under a low magnetic field corresponding to . We find that
the transverse voltage vanishes only in the directions of maximum symmetry of
the square lattice: the [10] and [01] direction (parallel bias) and the [11]
direction (diagonal bias). For orientations different than the symmetry
directions, we find a finite transverse voltage which depends strongly on the
angle of the current. We find that vortex motion is pinned in the [10]
direction (), meaning that the voltage response is insensitive to small
changes in the orientation of the current near . We call this
phenomenon orientational pinning. This leads to a finite transverse critical
current for a bias at and to a transverse voltage for a bias at
. On the other hand, for diagonal bias in the [11] direction the
behavior is highly unstable against small variations of , leading to a
rapid change from zero transverse voltage to a large transverse voltage within
a few degrees. This last behavior is in good agreement with our measurements in
arrays with a quasi-diagonal current drive.Comment: 9 pages, 9 figure
Non-Linear 3D Hybrid Kinetic-MHD Simulations of Alfvén Eigenmodes in the ASDEX Upgrade Tokamak
EUROfusion Consortium 63305
Two-year clinical outcome from the Iberian registry patients after left atrial appendage closure
AIMS:
The aim of this study was to observe the percentage of thromboembolic and haemorrhagic events over a 2-year follow-up in patients with non-valvular atrial fibrillation (NVAF) undergoing closure of the left atrial appendage (LAA) with an occlusion device. Observed events and CHADS2 (congestive heart failure, hypertension, age, diabetes, stroke history), CHA2DS2-VASc (also adding: vascular disease and sex) and HAS-BLED (hypertension, abnormal liver/renal function, stroke history, bleeding predisposition, labile international normalised ratios, elderly, drugs/alcohol use)-predicted events were compared.
METHODS:
LAA closure with an occlusion device was performed in 167 NVAF patients contraindicated for oral anticoagulants and recruited from 12 hospitals between 2009 and 2013. At least two transoesophageal echocardiograms were performed in the first 6 months postimplantation. Antithrombotics included clopidogrel and aspirin. Patients were monitored for death, stroke, major and relevant bleeding and hospitalisation for concomitant conditions. Mean age was 74.68±8.58, median follow-up was 24 months, 5.38% had intraoperative complications and implantation was successful in 94.6% of subjects. Mortality during follow-up was 10.8%, mostly (9.5%) non-cardiac related. Bleeding occurred in 10.1% of subjects, 5.7% major and 4.4% minor though relevant, and 4.4% suffered stroke. Major bleeding and stroke/transient ischaemic attack events within 2 years (annual event rates, 290 patients/year) were less frequent than expected from CHADS2 (2.4% vs 9.6%), CHA2DS2-VASc (2.4% vs 8.3%) and HAS-BLED (3.1% vs 6.6%) risk scores (p<0.001, p=0.003, p=0.047, respectively).
CONCLUSIONS:
LAA closure with an occlusion device in patients contraindicated for oral anticoagulants is a therapeutic option associated with fewer thromboembolic and haemorrhagic events than expected from risk scores, particularly in the second year postimplantation
Astrophysical S factor for the He-4(He-3,gamma)Be-7 reaction at medium energies
3 pags., 1 tab. -- Nuclear Physics in Astrophysics V 3–8 April 2011, Eilat, IsraelThe astrophysical S factor for the He-4(He-3,gamma)Be-7 direct capture reaction plays a major role in the context of solar neutrino flux and primordial Li-7 abundances that demand accurate information on the reaction. We report here our recent cross section measurements using the activation method in the region of E-CM=900-2800 keV, that aim to shed light on the discrepancies in the existing data and lead to a more accurate extrapolation of the S factor
Evaluation of Natural Language Processing for the Identification of Crohn Disease-Related Variables in Spanish Electronic Health Records:A Validation Study for the PREMONITION-CD Project
Background: The exploration of clinically relevant information in the free text of electronic health records (EHRs) holds the potential to positively impact clinical practice as well as knowledge regarding Crohn disease (CD), an inflammatory bowel disease that may affect any segment of the gastrointestinal tract. The EHRead technology, a clinical natural language processing (cNLP) system, was designed to detect and extract clinical information from narratives in the clinical notes contained in EHRs. Objective: The aim of this study is to validate the performance of the EHRead technology in identifying information of patients with CD. Methods: We used the EHRead technology to explore and extract CD-related clinical information from EHRs. To validate this tool, we compared the output of the EHRead technology with a manually curated gold standard to assess the quality of our cNLP system in detecting records containing any reference to CD and its related variables. Results: The validation metrics for the main variable (CD) were a precision of 0.88, a recall of 0.98, and an F1 score of 0.93. Regarding the secondary variables, we obtained a precision of 0.91, a recall of 0.71, and an F1 score of 0.80 for CD flare, while for the variable vedolizumab (treatment), a precision, recall, and F1 score of 0.86, 0.94, and 0.90 were obtained, respectively. Conclusions: This evaluation demonstrates the ability of the EHRead technology to identify patients with CD and their related variables from the free text of EHRs. To the best of our knowledge, this study is the first to use a cNLP system for the identification of CD in EHRs written in Spanish. © 2022 JMIR Medical Informatics. All rights reserved
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