Spin-orbit excitations of quantum wells

Confinement asymmetry effects on the photoabsorption of a quantum well are discussed by means of a sum-rules approach using a Hamiltonian including a Rashba spin-orbt coupling. We show that while the strength of the excitation is zero when the spin-orbit coupling is neglected, the inclusion of the spin-orbit interaction gives rise to a non zero strength and mean excitation energy in the far-infrared region. A simple expression for these quantities up to the second order in the Rashba parameter was derived. The effect of two-body Coulomb interaction is then studied by means of a Quantum Monte Carlo calculation, showing that electron-electron correlations induce only a small deviation from the independent particle model result

Caracterización geológica de la región de enlace entre la Cuenca de Bransfield y la Dorsal Sur de Scotia (Antártida)

In February 1992, a geological and geophysical survey was carried out in the NW Antarctic Peninsula region, between South Shetland, Elephant and Orkney Islands (Antarctica), during the "Scotia 92" cruise aboard BIO Hespérides. The multi-channel seismics, magnetics and gravity data show the different sedimentary characteristics between Scotia and Powell Basins. At the western end of the South Scotia Ridge (SSR), an area (50 x 100 km) covered by multibearn bathymetry reveals a maximum depth of more than 5,300 m corresponding to what we refer to as the Hespérides Deep. The SSR is a sinistral transform plate boundary between the Scotia and Antarctic plates (on the north and south respectively). The morphology of the SSR is constituted by two ridges separated by a deep and narrow valiey (10 to 30 km wide). Two main families of faults can be distinguished, one trending E-W and parallel to the plate boundary, and another one trending NW-SE. We iriterpret that the former accommodates the regional strike-slip motion, whereas the later has an extensional component which may be related to the main trend of Bransfield Basin. The rhomboid-shape of the Deep is the result of the interplay between both sets of faults. Assuming that the transform boundary runs between the two ridges we consider that the Hesperides Deep is a smaU puli-apart basin developed by the sinistral strike-slip motion along the SSR

Towards time-dependent current-density-functional theory in the non-linear regime.

Time-Dependent Density-Functional Theory (TDDFT) is a well-established theoretical approach to describe and understand irradiation processes in clusters and molecules. However, within the so-called adiabatic local density approximation (ALDA) to the exchange-correlation (xc) potential, TDDFT can show insufficiencies, particularly in violently dynamical processes. This is because within ALDA the xc potential is instantaneous and is a local functional of the density, which means that this approximation neglects memory effects and long-range effects. A way to go beyond ALDA is to use Time-Dependent Current-Density-Functional Theory (TDCDFT), in which the basic quantity is the current density rather than the density as in TDDFT. This has been shown to offer an adequate account of dissipation in the linear domain when the Vignale-Kohn (VK) functional is used. Here, we go beyond the linear regime and we explore this formulation in the time domain. In this case, the equations become very involved making the computation out of reach; we hence propose an approximation to the VK functional which allows us to calculate the dynamics in real time and at the same time to keep most of the physics described by the VK functional. We apply this formulation to the calculation of the time-dependent dipole moment of Ca, Mg and Na2. Our results show trends similar to what was previously observed in model systems or within linear response. In the non-linear domain, our results show that relaxation times do not decrease with increasing deposited excitation energy, which sets some limitations to the practical use of TDCDFT in such a domain of excitations.We thank French research funding agency ANR and Institut Universitaire de France for support during the realization of this work. J.M.E. acknowledges the support of EPSRC Grant No. EP/J015059/1. P.R. and J.M.E. would like to thank J. A. Berger for fruitful discussions.Copyright (2015) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in The Journal of Chemical Physics 2015, 142, 084118 and may be found at http://dx.doi.org/10.1063/1.4913291

A one-year follow-up study of the Symbol Digit Modalities Test (SDMT) and the Paced Auditory Serial Addition Test (PASAT) in relapsing-remitting multiple sclerosis : an appraisal of comparative longitudinal sensitivity

Altres ajuts: We also thank Ignasi Gich from Department of Epidemiology, Hospital de la Santa Creu i Sant Pau for his advice on statistical analysis.Neuropsychological batteries are infrequently used to assess cognitive impairment in multiple sclerosis because they are time-consuming and require trained personnel. The Symbol Digit Modalities Test (SDMT) is suggested to be a useful screening tool to measure cognitive impairment in multiple sclerosis patients and is more valid and reliable over time than the Paced Auditory Serial Addition Test (PASAT). The purpose of this study was to evaluate which of these tests was more sensitive to cognitive impairment at one-year follow-up. A total of 237 patients with relapsing-remitting multiple sclerosis and 57 healthy controls underwent a complete neuropsychological assessment. One year later, we assessed 196 patients using the Brief Repeatable Battery of Neuropsychological Tests. We also administered other executive function and prospective memory tests, together with fatigue and depression questionnaires. A total of 33.8% of patients were classified as cognitively impaired. The SDMT and the PASAT 3 seconds test (PASAT3) had a sensitivity of 0.809 and 0.783, respectively, thereby classifying patients as cognitively impaired. Analysis of 196 patients one year later showed 31.6% had cognitive impairment compared with 27.6% at the first assessment. The sensitivity to detect cognitive impairment after one year was 0.824 for SDMT and 0.796 for PASAT3. When the predictors were removed from the comparative standard battery, SDMT still showed a slightly higher sensitivity. Both SDMT and PASAT3 correlated significantly with all tests, but SDMT showed higher correlation values. Furthermore, SDMT was completed by all subjects while PASAT3 was completed by 86.9% of patients and 94.7% of controls. SDMT is simpler to administer than PASAT3 and may be slightly more sensitive to MS cognitive impairment. It could thus be a suitable test to assess cognitive impairment routinely in people with relapsing-remitting multiple sclerosis

Unraveling the sequence of serpentinization reactions : petrography, mineral chemistry, and petrophysics of serpentinites from MAR 15°N (ODP Leg 209, Site 1274)

Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 33 (2006): L13306, doi:10.1029/2006GL025681.The results of detailed textural, mineral chemical, and petrophysical studies shed new light on the poorly constrained fluid-rock reaction pathways during retrograde serpentinization at mid-ocean ridges. Uniformly depleted harzburgites and dunites from the Mid-Atlantic Ridge at 15°N show variable extents of static serpentinization. They reveal a simple sequence of reactions: serpentinization of olivine and development of a typical mesh texture with serpentine-brucite mesh rims, followed by replacement of olivine mesh centers by serpentine and brucite. The serpentine mesh rims on relic olivine are devoid of magnetite. Conversely, domains in the rock that are completely serpentinized show abundant magnetite. We propose that low-fluid-flux serpentinization of olivine to serpentine and ferroan brucite is followed by later stages of serpentinization under more open-system conditions and formation of magnetite by the breakdown of ferroan brucite. Modeling of this sequence of reactions can account for covariations in magnetic susceptibility and grain density of the rocks.Funding for this research was provided by USSSP and NSF-OCE grant 9986135. WB acknowledges support through a fellowship by the Deep Ocean Exploration Institute

Factores psicosociales asociados a la tecno-adicción en jóvenes: revisión sistemática de literatura

El uso de la tecnología en la vida cotidiana en la sociedad contemporánea se ha convertido en una herramienta de gran importancia, trayendo consigo, además, la preocupación sobre conductas nocivas en su respectivo uso, con tendencia al abuso o adicción. La vulnerabilidad hacia este comportamiento se observa en población joven, debido a la exposición desde temprana edad y falta de concientización. Objetivo: sistematizar información derivada de estudios empíricos realizados durante los últimos 5 años sobre los factores psicosociales asociados al riesgo de adición a medios tecnológicos. Método: el estudio de enfoque cualitativo, nivel descriptivo y método de revisión bibliográfica sistemática, incluyo como muestra 21 artículos, se empelo la metodologia de revisión basada en los criterios PRISMA. Resultados: las categorías emergentes identificadas a partir de análisis fueron: características comportamentales, rasgos de personalidad, características del contexto social y variables sociodemográficos, rasgos psicopatológicos, autoesquemas (autoestima, autocontrol, autoeficacia), habilidades para la vida, habilidades sociales y socioemocionales, esquemas maladaptativos tempranos y apego, satisfacción con la vida Conclusiones: se evidencia la necesidad de implementar medidas preventivas en los ambientes familiares y escolares desde las edades tempranas con el fin de disminuir el riesgo de tecnoadicción

Globally aligned photomosaic of the Lucky Strike hydrothermal vent field (Mid-Atlantic Ridge, 37°18.5′N) : release of georeferenced data, mosaic construction, and viewing software

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 9 (2008): Q12009, doi:10.1029/2008GC002204.We present a georeferenced photomosaic of the Lucky Strike hydrothermal vent field (Mid-Atlantic Ridge, 37°18′N). The photomosaic was generated from digital photographs acquired using the ARGO II seafloor imaging system during the 1996 LUSTRE cruise, which surveyed a ∼1 km2 zone and provided a coverage of ∼20% of the seafloor. The photomosaic has a pixel resolution of 15 mm and encloses the areas with known active hydrothermal venting. The final mosaic is generated after an optimization that includes the automatic detection of the same benthic features across different images (feature-matching), followed by a global alignment of images based on the vehicle navigation. We also provide software to construct mosaics from large sets of images for which georeferencing information exists (location, attitude, and altitude per image), to visualize them, and to extract data. Georeferencing information can be provided by the raw navigation data (collected during the survey) or result from the optimization obtained from image matching. Mosaics based solely on navigation can be readily generated by any user but the optimization and global alignment of the mosaic requires a case-by-case approach for which no universally software is available. The Lucky Strike photomosaics (optimized and navigated-only) are publicly available through the Marine Geoscience Data System (MGDS, http://www.marine-geo.org). The mosaic-generating and viewing software is available through the Computer Vision and Robotics Group Web page at the University of Girona (http://eia.udg.es/∼rafa/mosaicviewer.html).This work has been supported by the EU Marie Curie RTNs MOMARNet (OD, RG, JE, LN, JF, NG) and FREESUBNet (RG, NG, XC), the Spanish Ministry of Science and Innovation (grant CTM2007–64751; RG, JE), CNRS and ANR (grant ANR NT05–3_42212, JE), ICREA (LN), and by the Generalitat de Catalunya (JE, RG). JF has been funded by MICINN under FPI grant BES-2006-12733 and NG has been supported by MICINN under the ‘‘Ramon y Cajal’’ program

Seismic evidence for large-scale compositional heterogeneity of oceanic core complexes

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 9 (2008): Q08002, doi:10.1029/2008GC002009.Long-lived detachment faults at mid-ocean ridges exhume deep-seated rocks to form oceanic core complexes (OCCs). Using large-offset (6 km) multichannel seismic data, we have derived two-dimensional seismic tomography models for three of the best developed OCCs on the Mid-Atlantic Ridge. Our results show that large lateral variations in P wave velocity occur within the upper ~0.5–1.7 km of the lithosphere. We observe good correlations between velocity structure and lithology as documented by in situ geological samples and seafloor morphology, and we use these correlations to show that gabbros are heterogeneously distributed as large (tens to >100 km2) bodies within serpentinized peridotites. Neither the gabbros nor the serpentinites show any systematic distribution with respect to along-isochron position within the enclosing spreading segment, indicating that melt extraction from the mantle is not necessarily focused at segment centers, as has been commonly inferred. In the spreading direction, gabbros are consistently present toward the terminations of the detachment faults. This suggests enhanced magmatism during the late stage of OCC formation due either to natural variability in the magmatic cycle or to decompression melting during footwall exhumation. Heat introduced into the rift valley by flow and crystallization of this melt could weaken the axial lithosphere and result in formation of new faults, and it therefore may explain eventual abandonment of detachments that form OCCs. Detailed seismic studies of the kind described here, when constrained by seafloor morphology and geological samples, can distinguish between major lithological units such as volcanics, gabbros, and serpentinized peridotites at lateral scales of a few kilometers. Thus such studies have tremendous potential to elucidate the internal structure of the shallow lithosphere and to help us understand the tectonic and magmatic processes by which they were emplaced.This research was supported by grants from the U.S. NSF-IODP Program

Toxicity results after treatment with Electronic Brachytherapy in patients with endometrial cancer

Poster Session [EP-2226] Purpose or Objective To analyse the toxicity outcomes after treatment with Electronic Brachytherapy (XB) in postsurgical endometrial cancer patients treated at our medical centre. Material and Methods Prospective study in which we selected 94 patients, between September/2015 and September/2017, that received treatment with XB administered twice a week after endometrial cancer surgery, with IMRT planificati on. The patients were divided in two groups: Group 1 (57/94) considered high risk received external beam radiotherapy (46Gy) followed by XB (15Gy in 5Gy fractions) and group 2 (37/94) considered intermediate risk received exclusive XB (25Gy in 5Gy fraction s). We analysed the median dose in bladder, rectum and sigmoid D2cc, V50, V35 with XB comparing the doses with Ir192. The vaginal mucosa, gastrointestinal (GI) and genitourinary (GU) toxicities were analysed with the Common Terminology Criteria for Adverse Events (CTCAE 4.0) scale. Results The median dose in bladder with XB vs. Ir192 was: 2cc 62.9 vs. 69.9%, V50 7.1 vs. 12.6Gy, V35 15 vs. 28.1. In rectum XB vs. Ir192 was: D 2cc 64.01% vs. 67.7%, V50 7.8 vs. 10.9Gy, V35 16.5 vs. 31.8Gy. In sigmoid XB vs. Ir 192 was: D 50.37%vs. 58.0%, V50 8.8 vs. 16.2Gy, V35 21.2 vs. 37.5Gy. The median follow- up was 11 months (range 1 - 23, 9 months). In group 1, acute vaginal mucositis (G1) was observed in 35.08% of the patients, GI toxicity (G1) in 5.26% and GU toxicity (G1) in 10.52%. In group 2, we observed acute vaginal mucositis G1 in 45% of the patients and G2 in 10.81%, GI toxicity (G1) occurred in 2.7% and GU toxicity (G1) was present in 16.21%. There was no grade 3 or greater toxicity in any of the groups. Late toxici ty was observed in only 4 patients: Mucositis (G1) in 3 patients and GU toxicity (G1) in 1 patient. Conclusion The dose received by the organs at risk with the XB is less compared to Ir192, with a good coverage of the PTV. The greater toxicity was observe d immediately after the treatment was finished with an important reduction of the symptoms after 6 months. This technique shows excellent results as for toxicity