Factorizing the time evolution operator

There is a widespread belief in the quantum physical community, and in textbooks used to teach Quantum Mechanics, that it is a difficult task to apply the time evolution operator Exp{-itH/h} on an initial wave function. That is to say, because the hamiltonian operator generally is the sum of two operators, then it is a difficult task to apply the time evolution operator on an initial wave function f(x,0), for it implies to apply terms operators like (a+b)^n. A possible solution of this problem is to factorize the time evolution operator and then apply successively the individual exponential operator on the initial wave function. However, the exponential operator does not directly factorize, i. e. Exp{a+b} is not equal to Exp{a}Exp{b}. In this work we present a useful procedure for factorizing the time evolution operator when the argument of the exponential is a sum of two operators, which obey specific commutation relations. Then, we apply the exponential operator as an evolution operator for the case of elementary unidimensional potentials, like the particle subject to a constant force and the harmonic oscillator. Also, we argue about an apparent paradox concerning the time evolution operator and non-spreading wave packets addressed previously in the literature.Comment: 24 pages; added references; one figure change

El mundo funerario Tardorromano en Baelo Claudia. Novedades de las intervenciones arqueológicas del 2005 en la muralla oriental

The first results of an archaeological excavation carried out in the Baelo Claudia city wall are shown. The area is the one between the so called “Puerta de Carteia” ant the 4th tower . Six stratigraphic soundings have been developed, fi ve of them outside the wall and only one inside. A late roman cementery has been discovered in the upper part of the sequence, dating back to the V-VII c. AD. An archaeological, paleoanthropologic, paleopathologic study of the skeletals, and the funeral ritual has been carried out. Eight tombs have been digged up, three double and four single, containing seven adults and four children. Two tombs show an interesting disposition of skeletal remains, some of them reusing the graves, and a newly born with an anomalous position. Also, animals phalanges could have been placed in the children tombs as amulets, as well as a marine shell probably as a symbol of a fi sherman. All of adults present skeletal stress work and nutritional indicators.Se presentan los primeros resultados de una actuación arqueológica realizada en la muralla oriental de Baelo Claudia, comprendida entre la denominada Puerta de Carteia y la torre 4. Se han realizado seis sondeos estratigráfi cos, cinco extramuros y uno al interior de la cinta muraria, en los cuales se ha documentado una necrópolis tardorromana (ss. V-VII d.C.) en la parte superior de la secuencia estratigráfi ca. Se exponen los resultados preliminares del estudio arqueológico, paleoantropológico y paleopatológico, y del ritual funerario, de los individuos hallados en las ocho tumbas excavadas. El total de individuos exhumados fue de once (siete adultos y cuatro infantiles), hallándose unos interesantes rituales de reutilización de las tumbas, un recién nacido en una posición “anómala” y falanges de animales depositadas, quizás como amuletos, así como una caracola como ajuar de un posible almadrabero. Tanto en hombres como en mujeres se advierten marcadores paleoocupacionales que muestran que realizaban una actividad laboral intensa

Notch/neurogenin 3 signalling is involved in the neuritogenic actions of oestradiol in developing hippocampal neurones

10 pages. - PMID: 21251092 [PubMed - in process]The ovarian hormone oestradiol promotes neuritic outgrowth in different neuronal types, by mechanisms that remain elusive. Recent studies have shown that the Notch-regulated transcription factor neurogenin 3 controls neuritogenesis. In the present study, we assessed whether oestradiol regulates neurogenin 3 in primary hippocampal neurones. As expected, neuritogenesis was increased in the cultures treated with oestradiol. However, the neuritogenic action of oestradiol was not prevented by ICI 182,780, an antagonist of classical oestrogen receptors (ERs). Oestradiol decreased the expression of Hairy and Enhancer of Split-1, a Notch-regulated gene that negatively controls the expression on neurogenin 3. Furthermore, oestradiol increased the expression of neurogenin 3 and regulated its distribution between the neuronal cell nucleus and the cytoplasm. The effect of oestradiol on neurogenin 3 expression was not blocked by antagonists of classical nuclear ER-mediated transcription and was not imitated by selective agonists of nuclear ERs. By contrast, G1, a ligand of G protein receptor 30/G protein-coupled ER, fully reproduced the effect of oestradiol on neuritogenesis, neurogenin 3 expression and neurogenin 3 subcellular localisation. Moreover, knockdown of neurogenin 3 in neurones by transfection with small interference RNA for neurogenin 3 completely abrogated the neuritogenic actions of oestradiol and G1. These results suggest that oestradiol regulates neurogenin 3 in primary hippocampal neurones by a nonclassical steroid signalling mechanism, which involves the down-regulation of Notch activity and the activation of G protein receptor 30/G protein-coupled ER or of other unknown G1 targets. In addition, our findings indicate that neurogenin 3 participates in the neuritogenic mechanisms of oestradiol in hippocampal neurones.Peer reviewe

Estudio clínico morfológico de la deformación del borde dorsal del cuello del burro de raza andaluza

The aim of this study was to a clinical, morphological of deformation dorsal neck edge on donkeys Andalusian in Bodonal de la Sierra, Extremadura, Spain. We studied a total of 31 donkeys. Clinical examination was performed and morphological considering weight and body condition was measured cervical perimeter. Deformation of the dorsal edge of the neck in all cases studied was evident. Morphological study was to consider the deformation of the dorsal edge of the neck considering the crest of the neck (score of 1 to 5) evidenced. 0 and 1 score-no donkey under these categories. Score 2 - 42 % Score. 3 - 32% score. 4 - 3 % and score 5 - 23%. The statistical results of the peso versus the cervical neck circumference showed a correlation coefficient of 0.773 and the score grade obese neck and body condition was 0.240. In conclusion lesions consistent with deformation of the dorsal edge of the neck in Andalusian breed donkeys were observed.Se plantea como objetivo un estudio clínico morfológico de la deformación del borde dorsal del cuello en burros de raza Andaluza en Bodonal de la Sierra, Extremadura-España. Fueron estudiados un total de 31 burros. Se practicó un examen clínico y morfológico considerando condición corporal peso y se midió el perímetro cervical. Se evidenció deformación del borde dorsal del cuello en todos los casos estudiados. El estudio morfológico para considerar la deformación del borde dorsal del cuello considerando la cresta de la nuca (puntuación del 1 al 5) evidencio: para Puntuación 0 y 1.- ningún burro bajo estas categorías. Puntuación 2.- 42%, Puntuación 3.- 32%, Puntuación 4.- 3% y Puntuación 5.- 23%. Los resultados estadísticos del peso versus el perímetro cervical del cuello presentaron un coeficiente de correlación de 0.773 y para el grado puntuación del cuello obeso y condición corporal fue de 0.240. En conclusión se observaron lesiones compatibles con la deformación del borde dorsal del cuello en burros de raza Andaluza

Hibridismo entre el lenguaje oral y el escrito: la comunicación a través del ordenador y las nuevas redes sociales

En este artículo presentamos diversos aspectos de interés relacionados con la comunicación a través del ordenador, centrándonos en las características específicas de la comunicación en las redes sociales y más concretamente en Facebook (FB). La oralización del texto escrito, es decir, texto que reproduce rasgos característicos de la conversación y que incluso a veces se lee reconstruyendo mental o verbalmente dichos rasgos, ha dado lugar a un nuevo género textual, híbrido entre el lenguaje oral y escrito. En las próximas páginas mostraremos algunas de las características más sobresalientes que definen este género e ilustraremos su producción con ejemplos de nuestras investigaciones que revelan algunos aspectos novedosos de la comunicación a través del ordenador en las redes sociales. La observación de la elevada frecuencia con la que se utiliza el lenguaje con una función evaluativa (Santamaría-García 2013 y en prensa, Maíz-Arévalo y García-Gómez, 2013), en muchos casos para la expresión de elogios y cumplidos (Maíz-Arévalo, 2013), ha motivado la elección del estudio de esta función en nuestros trabajos. También resulta de especial interés comprobar la importancia de la evaluación en la construcción de la imagen pública de los usuarios y en la relación social que se establecerá entre ellos (Santamaría-García 2013 y en prensa).Proyecto “Funciones Discursivas: La Evaluación en Distintos Tipos Textuales" (FUNDETT), FFI2009-07308, financiado por el Ministerio de Ciencia e Innovació

Approach to the Lower Pliocene marine-continental correlation from southern Spain. The micrommamal site of Alhaurín el Grande-1 (Málaga Basin, Betic Cordillera, Spain)

A new micromammal site at Alhaurín el Grande (Málaga, southern Spain) located above early Pliocene marine deposits allows an approach to the marine-continental correlation for this age. The early Pliocene marine filling throughout the Málaga Basin is developed in three transgressive-regressive sequences (Pl-1, Pl-2, and Pl-3 units) bounded by discontinuities. At the top of the intermediate sequence Pl-2, peaty sediments have yielded fossils of Rodentia, Lagomorpha, Insectivora, and Crocodylia. The presence of Cricetus barrieri Mein & Michaux, 1970 in combination with murids, both of primitive morphology, such as Apodemus gudrunae Van de Weerd, 1976, and more advanced forms (i.e. Occitanomys brailloni Michaux, 1969 and Stephanomys donnezani cordii Ruiz Bustos, 1986), points to an early Ruscinian age (MN 14 biozone). Based on the planktonic foraminifers, the biostratigraphic data indicate that marine sediments just below the micromammal beds belong to the MPl-2 biozone of the early Zanclean. Available paleomagnetic data from the marine sediments show that the micromammal bed must be located between the normal geomagnetic subchron C3n3n (4.89-4.80 Ma) and the subchron C3n2n (4.63-4.49 Ma), limiting the age of this site to the late part of the early Zanclean

Sacrolistesis postraumática sin lesión neurológica

Las fracturas transversas de sacro son raras pero aún lo son más aquellas en las que hay un desplazamiento o listeis de una vértebra sacra sobre otra. El sentido de desplazamiento viene condicionado por el mecanismo causante, pudiendo ser en flexión o en extensión. En las verdaderas listesis el sentido del traumatismo es en extensión, llevando a colocarse total o parcialmente la vértebra sacra superior por delante de la inferior. En determinados casos como pueden ser los politraumatizados, el diagnóstico puede ser difícil, por lo que es necesario realizar un estudio radiológico meticuloso. En estas fracturas ocurre frecuentemente una lesión de raíces lumbosacras de mayor o menor gravedad, aunque suele existir algún tipo de recuperación, incluso espontánea, con el transcurso del tiempo. Se presenta el caso de una mujer que presentó una sacrolistesis de S1 sobre S2 por haber sufrido caída de nalgas, sin existir ninguna lesión neurológica.Transverse fractures of the sacrum are rare, but fractures with displacement or listhesis of one sacral vertebra over another are even more infrequent. The direction of the displacement is conditioned by the causing mechanism and may occur in flexion or extension, in true listhesis, trauma occurs in extension, placing the superior sacral vertebra totally or partially in from of the inferior vertebra. In some cases, such as multiple traumas, the diagnosis can be difficult, and a careful radiologic study is required. A more or less severe injury of th lumbosacral roots frequently occurs in these fractures, although a certain degree of recovery takes place, even spontaneously, over time. We present the case of a 69 years old woman suffering from a sacrolisthesis of S1 over S2 after a fall on the buttocks with no neurological lesion

Constraining the X-ray reflection in low accretion rate AGN using XMM-Newton, NuSTAR and Swift

An interesting feature in active galactic nuclei (AGN) accreting at low rate is the weakness of the reflection features in their X-ray spectra, which can result from the gradual disappearance of the torus with decreasing accretion rates. It has been suggested that low luminosity AGN (LLAGN) would have a different reflector configuration compared with high luminosity AGN, either covering a smaller fraction of the sky or simply having less material. Additionally, we note that the determination of the spectral index ($\Gamma$) and the cut-off energy of the primary power-law emission is affected by the inclusion of reflection models, showing the importance of using them to study the accretion mechanism, especially in the case of the LLAGN that have previously shown a high dispersion on the relation between $\Gamma$ and the accretion rate. Our purpose is to constrain the geometry and column density of the reflector in a sample of LLAGN covering a broad X-ray range of energy combining data from XMM-Newton + NuSTAR + Swift of a hard X-ray-flux limited sample of 17 LLAGN from BASS/DR2 with accretion rates $\lambda_{Edd}$=L$_{\rm Bol}$/L$_{\rm Edd}$<10$^{-3}$. We fit all spectra using the reflection model for torus (borus02) and accretion disk (Xillver) reflectors. We found a tentative correlation between the torus column density and the accretion rate, LLAGN shows a lower column density compared with the high-luminosity objects. We also confirm the relation between $\Gamma$ and $\lambda_{Edd}$, with a smaller scatter than previously reported, thanks to the inclusion of high-energy data and the reflection models. Our results are consistent with a break at $\lambda_{Edd}\sim10^{-3}$, suggestive of a different accretion mechanism compared with higher accretion AGN.Comment: Accepted for publication in Astronomy & Astrophysic

Power distribution in a 13 kW three-phase rectifier system: impact on weight, volume and efficiency

This paper addresses the power delivery strategy on an aircraft application consisting on seven isolated DC loads to be supplied from the AC grid. Distributed or centralized power processing is evaluated taking into account weight and efficiency. Additionally, the rectifier switching frequency has to be synchronized with an external frequency clock to minimize the interference of the converter harmonics with the loads