147 research outputs found

    Temporal factorization of a non-stationary electromagnetic cavity field

    Full text link
    When an electromagnetic field is confined in a cavity of variable length, real photons may be generated from vacuum fluctuations due to highly nonadiabatic boundary conditions. The corresponding effective Hamiltonian is time-dependent and contains infinite intermode interactions. Considering one of the cavity mirrors fixed and the other describing uniform motion (zero acceleration), we show that it is possible to factorize the entire temporal dependency and write its formal solution, i.e., the Hamiltonian becomes a product of a time-dependent function and a time-independent operator. With this factorization, we prove in detail that the photon production is proportional to the Planck factor involving a velocity-dependent effective temperature. This temperature significantly limits photon generation even for ultra-relativistic motion. The time-dependent unitary transformations we introduce to obtain temporal factorization help establishing connections with the shortcuts to adiabaticity of quantum thermodynamics and with the quantum Arnold transformation.Comment: 10 pages, 4 figures. Accepted in Phys. Rev.

    Temporal evolution of a driven optomechanical system in the strong coupling regime

    Full text link
    We obtain a time-evolution operator for a forced optomechanical quantum system using Lie algebraic methods when the normalized coupling between the electromagnetic field and a mechanical oscillator, G/ωmG/\omega_m, is not negligible compared to one. Due to the forcing term, the interaction picture Hamiltonian contains the number operator in the exponents, and in order to deal with it, we approximate these exponentials by their average values taken between initial coherent states. Our approximation is justified when we compare our results with the numerical solution of the number of photons, phonons, Mandel parameter, and the Wigner function, showing an excellent agreement.Comment: 21 pages, 11 figure

    Personality in patients with migraine evaluated with the "Temperament and Character Inventory"

    Get PDF
    The objective of this study was to assess the personality profile of a sample of Mexican patients with migraine using the Temperament and Character Inventory (TCI). A cross-sectional study was performed including adult migraine patients identified from the outpatient neurology clinics of two large teaching hospitals in Mexico City. Patients were asked to voluntarily participate in the study. A physician conducted a standardised diagnostic interview adhering to the criteria of the International Headache Society (IHS). Patients were interviewed and administered the TCI. We used two healthy controls groups and a third group of non-migraine pain controls. One hundred and fortytwo subjects with migraine, 108 healthy blood donors, 269 young healthy controls and 30 patients with non-migraine pain (NMP) were included in the study. Patients with migraine had higher scores in the dimension harm avoidance (HA) and all its sub-dimensions (p<0.05) than healthy patients. Patients with non-migraine pain had high scores in HA and low scores in novelty seeking, self-directedness and cooperativeness. Blood donors had high scores in the following subdimensions: HA1, HA4 and C3 (Cooperativeness). Personality features consistent with migraine are avoidance, rigidity, reserve and obsessivity. Our study shows that patients with chronic pain share some of the personality features of patients with migraine but their TCI profile could be indicative of cluster C avoidant personality. Blood donors were shown to have more energy, with a tendency to help other people and be more optimistic. The results support serotoninergic involvement as explaining the physiopathology of migraine

    Propuesta de una herramienta de soporte para QuEF

    Get PDF
    A día de hoy, existen múltiples y diversas metodologías Web que trabajan con el paradigma guiado por modelos, las cuales están siendo aplicadas con éxito en entornos industriales reales. Sin embargo, en estos tiempos de cambios y de constante innovación tecnológica, siguen surgiendo nuevas metodologías y además los usuarios y diseñadores de éstas tiene la necesidad de mejorarlas. Por otra parte, surge la necesidad de analizar, evaluar y mejorar la calidad las propuestas. QuEF (Quality Evaluation Framework) es un entorno diseñado para la gestión de la calidad de metodologías de ingeniería Web guiadas por modelos (MDWE o Model-Driven Web Engineering) con el fin de facilitar el análisis, evaluación, control y mejora continua de la calidad de éstas. En el presente trabajo, se describe una herramienta de soporte para implementar dicho entorno.Ministerio de Educación y Ciencia TIN2007-67843- C06-03Ministerio de Educación y Ciencia TIN2010-20057-C03-0

    Paleoclimate reconstruction of the last 36 kyr based on branched glycerol dialkyl glycerol tetraethers in the Padul palaeolake record (Sierra Nevada, southern Iberian Peninsula)

    Get PDF
    Quantitative continental climate reconstructions covering the last glacial cycle from the Iberian Peninsula are scarce. In order to fill this gap, we obtained for the first time a high-resolution mean annual air temperature (MAAT) record based on the distribution of specific bacterial membrane lipids (i.e., branched glycerol dialkyl glycerol tetraethers; brGDGTs) from the last 36.0-4.7 kyr palaeolake record recovered by the Padul-15-05 sedimentary core (Padul, Sierra Nevada, southern Iberia). The fractional abundance of the three major groups of GDGTs present in the Padul sediments, GDGT-0, crenarchaeol and the summed brGDGTs, is comparable with that of other shallow and small (Peer reviewe

    Vegetation and geochemical responses to Holocene rapid climate change in the Sierra Nevada (southeastern Iberia): the Laguna Hondera record

    Get PDF
    High-altitude peat bogs and lacustrine records are very sensitive to climate changes and atmospheric dust input. Recent studies have shown a close relationship between regional climate aridity and enhanced eolian input to lake sediments. However, changes in regional-scale dust fluxes due to climate variability at short scales and how alpine environments were impacted by climatic- and human-induced environmental changes are not completely understood.Here we present a multi-proxy (palynological, geochemical and magnetic susceptibility) lake sediment record of climate variability in the Sierra Nevada (southeastern Iberian Peninsula) over the Holocene. Magnetic susceptibility and geochemical proxies obtained from the high mountain lake record of Laguna Hondera evidence humid conditions during the early Holocene, while a trend towards more arid conditions is recognized since  ∼ 7000&thinsp;cal&thinsp;yr&thinsp;BP, with enhanced Saharan eolian dust deposition until the present. This trend towards enhanced arid conditions was modulated by millennial-scale climate variability. Relative humid conditions occurred during the Iberian Roman Humid Period (2600–1450&thinsp;cal&thinsp;yr&thinsp;BP) and predominantly arid conditions occurred during the Dark Ages and the Medieval Climate Anomaly (1450–650&thinsp;cal&thinsp;yr&thinsp;BP). The Little Ice Age (650–150&thinsp;cal&thinsp;yr&thinsp;BP) is characterized in the Laguna Hondera record by an increase in runoff and a minimum in eolian input. In addition, we further suggest that human impact in the area is noticed through the record of Olea cultivation, Pinus reforestation and Pb pollution during the Industrial Period (150&thinsp;cal&thinsp;yr&thinsp;BP–present). Furthermore, we estimated that the correlation between Zr and Ca concentrations stands for Saharan dust input to the Sierra Nevada lake records. These assumptions support that present-day biochemical observations, pointing to eolian input as the main inorganic nutrient source for oligotrophic mountain lakes, are comparable to the past record of eolian supply to these high-altitude lakes.</p

    Revista de Vertebrados de la Estación Biológica de Doñana

    Get PDF
    Contribución al estudio de la bermejuela Rutilus arcasi, Steindachner, 1866 de la cuenca del Júcar (Osteichthyes: Cyprinidae)II. Edad y crecimientoSobre la taxonomía de Barbus comiza Steindachner, 1865 (Ostariophysi: Cyprinidae)Fenología de una comunidad de anfibios asociada a cursos fluviales temporales.Nueva especie para la ciencia de Anolis (Lacertilia: Iguanidae) de Cuba pertenecient eal complejo argillaceusSegregación ecológica en una comunidad de ofidios.El Aguila Imperial (Aquila adalberti): dispersión de los jóvenes, estructura de edades y mortalidaSobre diferencias individuales en la alimentación de Tyto albaInfluencia de las condiciones ambientales sobre la organización de la comunidad de aves invernantes en un bosque subalpino mediterráneoVariaciones en la agregación y distribución de la cabra montés (Capra pyrenaica Schinz,1838) detectadas con un muestreo de excrementosAlimentación del conejo (Oryctolagus cuniculus L. 1758) en Doñana. SO, EspañaSobre la distribución de Barbus meridionales Risso, 1826 (Ostariophysi: Cyprinidae) en la Península IbéricaSobre la distribución de Barbus meridionales Risso, 1826 (Ostariophysi: Cyprinidae) en la Península IbéricaNueva cita de Barbus microcephalus Almaça (Pisces, Cyprinidae) en España.Revisión taxonómica y distribución de Cobitis maroccana Pellegrin, 1929 (Osteichthyes, Cobitidae)Datos sobre una población de Lacerta viviparaSobre la presencia de Emys orbicularis en la provincia de León.Algunas observaciones sobre la captura de quirópteros por Falco subbuteo y Falco tinunculusNyctalus leisleri (Kuhk, 1818) (Mammalia: Chiroptera). Una nueva especie para las islas CanariaNuevos datos acerca de la distribución del topillo campesino Microtus arvalis, PALLAS 1778, en la Península IbéricaPeer reviewe
    • …
    corecore