3,161 research outputs found
Delocalization and wave-packet dynamics in one-dimensional diluted Anderson models
We study the nature of one-electron eigen-states in a one-dimensional diluted
Anderson model where every Anderson impurity is diluted by a periodic function
. Using renormalization group and transfer matrix techniques, we provide
accurate estimates of the extended states which appear in this model, whose
number depends on the symmetry of the diluting function . The density of
states (DOS) for this model is also numerically obtained and its main features
are related to the symmetries of the diluting function . Further, we show
that the emergence of extended states promotes a sub-diffusive spread of an
initially localized wave-packet.Comment: 6 pages, 6 figures, to appear in EPJ
Nivel de satisfacción de las mujeres, en la atención del parto vaginal en la sala de puerperio fisiológico del Hospital Bertha Calderon Roque en el período de Abril–Agosto del 2014
La satisfacción de la mujer con la experiencia delnacimiento de su hijo es un indicador importante en la calidad de los servicios de atención obstétricos. El presente estudio se realizó bajo el marco conceptual de Mackey Childbirth Scale 1998). El cual considera cinco componentes de la satisfacción: ella misma, hijo, enfermera, médico y acompañante.El objetivo del presente trabajo fue determinar la satisfacción materna con la experiencia del nacimiento de su hijo considerando a la parturienta como un todo en su evaluación integral.Se realizó un estudio descriptivo de corte trasversal, con muestreo probabilístico en las salas de puerperio fisiológico mediato del Hospital Bertha Calderón, se contó con una población a estudio de 240 puérperas, como instrumento de medición se tomó en cuenta la escala antes descrita. Para su análisis estadístico se interpretó en porcentajes y frecuencias.Entre los hallazgos encontrados en este estudio se encontró el principal grupo etario que dio a luz fue las edades comprendidas entre 21 y 25 años, con escolaridad secundaria, unión estable de ocupación de ama de casa. Como tal se logró apreciar que las pacientes clasifican su experiencia de parto como positiva durante su proceso de parto vaginal
Professional Skills and Profiles in Journalism Demanded by Companies: Analysis of Offers at LinkedIn and Infojobs
The goal of this research is to analyze whether the profiles and professional skills in journalism demanded by companies in Spain correspond to those compiled in the Libro Blanco of the ANECA, or whether they have been modified over a decade later by the impact of the digital era and emergence of new employment needs. In the current setting of rapid and unpredictable changes, periodic analyses and research like this study are necessary. The methodology chosen was the analysis of the content of job offers directed to journalism graduates on the two most used job portals in Spain, Infojobs and LinkedIn, in September 2017. All the information in the offers was organized into two categories related to descriptive data about types of contracts and data over required skills. The results led to the conclusion that the professional skills currently demanded of journalism graduates differ qualitatively and quantitatively from the professional skills described by the ANECA in 2005. The skills most demanded by companies respond to the emergence of new professional profiles related to Web 2.0. However, it is also the case that companies do not seem to know precisely what skills a journalism graduate must have
Variaciones anatómicas de raíces y sistema de canales radiculares, que causan fracaso endodóntico en primer y segundo molar superior permanente, encontradas con tomografía computarizada de haz cónico. Revisión de la literatura.
74 p.INTRODUCCIÓN: Los molares superiores permanentes reciben tratamientos
endodónticos en forma frecuente y presentan la mayor complejidad anatómica, tanto a nivel radicular como en su sistema canalicular. El no identificarlas, repercutirá en no lograr el objetivo del tratamiento de canales radiculares, y se traducirá en un fracaso terapéutico. La
tomografía computarizada de haz cónico (CBCT) presenta ventajas para detectar dichas variaciones, respecto a la radiografía retroalveolar, pues no tiene el inconveniente de la superposición de estructuras anatómicas. OBJETIVO GENERAL: Determinar las variaciones anatómicas de raíces y sistema de canales radiculares causantes de fracaso endodóntico en primeros y segundos molares superiores permanentes, encontradas con CBCT, en casos publicados en la literatura. MATERIALES Y MÉTODOS: Estudio
observacional, retrospectivo y de corte transversal. Revisión bibliográfica en línea, durante el periodo marzo-agosto del año 2016. RESULTADOS: De un total de 492 artículos revisados en la literatura, se obtuvo una muestra de 16 casos. El fracaso endodóntico asociado a una variación anatómica, se presentó mayormente en primer molar superior. El 81,25% de la muestra, fueron molares con 3 raíces diferenciadas y 4 canales radiculares. La variación anatómica mayormente encontrada, fue la presencia del canal MB2, representando el 75% de los casos. También se presentaron variaciones anatómicas en los canales radiculares, por fusión de las raíces. CONCLUSIONES: El examen CBCT permite
identificar variaciones anatómicas en las raíces y sistema canalicular de molares superiores. Podría utilizarse en forma previa al tratamiento inicial o ya ante la presencia de fracaso en el tratamiento endodóntico. PALABRAS CLAVE: tomografía computarizada de haz cónico, cone-beam computed tomography, CBCT, fracaso endodóntico, root canal therapy, retreatment, molar, tooth root, periapical diseases
Headache features in people with whiplash associated disorders: A scoping review.
Whiplash-associated headache (WAH) is one of the most common symptoms after a whiplash injury, leading to high disability. Nevertheless, the clinical characteristics of WAH have not been well described. To synthesise the existing literature on the clinical characteristics of WAH. Scoping review. The protocol for this scoping review was registered in Open Science Framework and the PRISMA extension for Scoping Reviews tool was used to ensure methodological and reporting quality. A systematic search was conducted in PubMed, EMBASE, CINAHL, Web of Science and Scopus. The search was performed by one author and the screening of articles was conducted by two authors independently. A total of 11363 articles were initially identified and finally 26 studies were included in the review. Headache intensity was the most commonly reported feature. Headache duration, frequency and location were also reported in at least four studies. Few studies reported physical impairments that may be related to the presence of WAH. A differentiation with concussion characteristics was only performed in eight studies. WAH appears to be of mild to moderate intensity, typically with episodes of short duration which is commonly experienced in the occipital region amongst other regions, and with a tendency to reduce in intensity over time. [Abstract copyright: Copyright © 2023. Published by Elsevier Ltd.
Extended States in a One-dimensional Generalized Dimer Model
The transmission coefficient for a one dimensional system is given in terms
of Chebyshev polynomials using the tight-binding model. This result is applied
to a system composed of two impurities located between sites of a host
lattice. It is found that the system has extended states for several values of
the energy. Analytical expressions are given for the impurity site energy in
terms of the electron's energy. The number of resonant states grows like the
number of host sites between the impurities. This property makes the system
interesting since it is a simple task to design a configuration with resonant
energy very close to the Fermi level .Comment: 4 pages, 3 figure
High-speed noise-free optical quantum memory
Quantum networks promise to revolutionise computing, simulation, and
communication. Light is the ideal information carrier for quantum networks, as
its properties are not degraded by noise in ambient conditions, and it can
support large bandwidths enabling fast operations and a large information
capacity. Quantum memories, devices that store, manipulate, and release on
demand quantum light, have been identified as critical components of photonic
quantum networks, because they facilitate scalability. However, any noise
introduced by the memory can render the device classical by destroying the
quantum character of the light. Here we introduce an intrinsically noise-free
memory protocol based on two-photon off-resonant cascaded absorption (ORCA). We
consequently demonstrate for the first time successful storage of GHz-bandwidth
heralded single photons in a warm atomic vapour with no added noise; confirmed
by the unaltered photon statistics upon recall. Our ORCA memory platform meets
the stringent noise-requirements for quantum memories whilst offering technical
simplicity and high-speed operation, and therefore is immediately applicable to
low-latency quantum networks
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