The Stationary Phase Method for a Wave Packet in a Semiconductor Layered System. The applicability of the method

Using the formal analysis made by Bohm in his book, {\em "Quantum theory"}, Dover Publications Inc. New York (1979), to calculate approximately the phase time for a transmitted and the reflected wave packets through a potential barrier, we calculate the phase time for a semiconductor system formed by different mesoscopic layers. The transmitted and the reflected wave packets are analyzed and the applicability of this procedure, based on the stationary phase of a wave packet, is considered in different conditions. For the applicability of the stationary phase method an expression is obtained in the case of the transmitted wave depending only on the derivatives of the phase, up to third order. This condition indicates whether the parameters of the system allow to define the wave packet by its leading term. The case of a multiple barrier systems is shown as an illustration of the results. This formalism includes the use of the Transfer Matrix to describe the central stratum, whether it is formed by one layer (the single barrier case), or two barriers and an inner well (the DBRT system), but one can assume that this stratum can be comprise of any number or any kind of semiconductor layers.Comment: 15 pages, 4 figures although figure 4 has 5 graph

Variability of B and Be stars in the LMC/SMC: binaries and pulsations

To study the variability of the 523 B and Be stars observed in the Magellanic clouds with the VLT-FLAMES, we cross-matched the stars of our sample with the photometric database MACHO, which provides for each star an 8 years lightcurve. We searched for long, medium, and short-term periodicity and found the eclipsing binaries in our sample. For these stars, combining, spectroscopy and photometry, we were able to provide information on several systems of stars (systemic velocities, ratios of masses, etc). We also present the ratios of B-binaries to B-non binaries in the LMC/SMC in comparison with the MW. Note that this ratio is also an important issue to understand the mechanism of star-formation at low metallicity. We also found the first multiperiodic B and Be stars in the SMC, in particular the first SMC Beta Cep and SPB, while, according to the models, pulsations were not foreseen in low metallicity environments, i.e. typically in the SMC. Our results show that the instability strips are shifted towards higher temperatures in comparison with the Milky Way' strips of pulsating B-type stars. By the fact that we found more pulsating Be stars than pulsating B stars in the SMC, it seems that the fast rotation favours the presence of pulsations. However, the ratio of pulsating B-type stars to "non"-pulsating B-type stars at low metallicity is lower than at high metallicity.Comment: poster IAUS25

Estudio empírico sobre la influencia de recursos heurísticos en la resolución de problemas de probabilidad condicionada L0 y L2

Se ha constatado la dificultad de los estudiantes a la hora de resolver problemas de probabilidad condicionada (Cañadas et al., 2011). En general, la complejidad de estos problemas es debida a varios factores: el formato y el orden en el que se presentan los datos, el contexto en el que se plantea el problema, el lenguaje utilizado para expresar los datos condicionales o las herramientas utilizadas en el proceso de resolución. En nuestro estudio nos centraremos en el uso y la influencia de recursos heurísticos, como tablas de contingencia o diagramas de árbol, durante la resolución de un problema de probabilidad condicionada

Efectos del deshojado precoz sobre la composición aromática del vino Albariño en el valle del Salnés (D.O. Rías Baixas)

Este trabajo pretende estudiar los efectos del deshojado precoz sobre la composición aromática del vino Albariño. Para ello se llevó a cabo el deshojado en dos estados fenológicos de la planta, floración y cuajado y a dos intensidades distintas, 4 y 8 hojas basales. Los resultados se compararon con un control en el que no se realizó ningún deshojado. Los análisis químicos clásicos no mostraron diferencias significativas para ningún parámetro estudiado entre los vinos elaborados con los distintos tratamientos. La identificación y cuantificación de los compuestos volátiles se realizó mediante cromatografía de Gases (GC-FID). Los resultados obtenidos mostraron diferencias significativas para 14 compuestos de los 36 analizados. Se podría concluir, en este primer año de estudio, que el deshojado precoz es capaz de aumentar la composición volátil del vino Albariño

Clinical characteristics, treatment and outcome of 28 oral haemangiomas in paediatric patients

Objective: To present a large series of oral haemangiomas in children, analyzing the clinical characteristics, treatment and outcome of oral haemangiomas in 28 children. Material and Methods: We conducted an observational retrospective study, reviewing medical records with clinical diagnosis of haemangioma between 1990 and 2006 at the Children?s Maxillofacial Surgery Service of the Hospital Universitario la Fe, Valencia. All patients with a clinical, radiographic, pathologically confirmed diagnosis of oral haemangioma were included. Results: The study included 28 patients (19 females and 9 males) with a mean age of 4.27 years (range 0-14 years). Nine were congenital haemangioma. The most frequent location of oral haemangioma was in the lip with 23 cases, followed by three cases in the tongue and 2 in the buccal mucosa. The mean diameter of the lesion was 1.67 cm (range 1-3cm). The mean duration of the lesion was 6.3 months (range 1 month to 5 years). Of the 28 haemangiomas, 13 were surgically removed, 2 were treated with embolization and 13 disappeared spontaneously. The mean follow up was 2.7 months (1-8 months). There were no cases of recurrence. Conclusions: Haemangiomas usually present in children, and can be seen from birth. They have a predilection for females. They are uncommon in the oral cavity. In the oral region, the most common location is the lip. Most congenital haemangioma regress spontaneously without treatment. The treatment of choice is surgical excision of the lesion

Orofacial dermoid cysts in pediatric patients : a review of 8 cases

Objective: The aim was to analyze the clinical characteristics, treatment and outcome of 8 orofacial dermoid cysts (DC) in pediatric patients. Material and Methods: A retrospective observational study was made, reviewing the medical records with clinical diagnosis of dermoid cyst between 1987 and 2006 in the Children?s Maxillofacial Surgery Department of the Hospital Universitario La Fe, Valencia, Spain. The following data were collected: sex, age, location, size and duration of the lesion, treatment, length of follow-up, and recurrence. Results: Eight patients (3 girls and 5 boys) with a mean age of 2.7 years (range 0-12 years). Four DC were located in the oral area (3 sublingual and 1 lingual), one in the periorbital and three in the nasal areas. The size ranged from 0.8 cm to 4 cm. The mean duration of the lesion was 13.7 months (range 4 days to 2 years). All DC were diagnosed pathologically following surgical removal of the lesion. There were no recurrences. Conclusion: The appearance of DC in the maxillofacial region of pediatric patients is uncommon. The floor of the mouth is the most frequently affected area in the oral cavity. Treatment is surgical removal of the lesion. Recurrence is unusual

Comorbidity between attention deficit hyperactivity disorder and reading disabilities: implications for assessment and treatment

Comorbidity of attention deficit hyperactivity disorder (ADHD) and reading disabilities (RD) is greater than what would occur by chance. Considering the well-documented adverse impact of both ADHD and RD on development, the presence of both conditions may lead to particularly poor outcomes for affected people. This chapter, which reviews 43 research studies carried out in the last decade that have focused on the link between ADHD and RD, is divided into two broad nuclei of contents. First, studies are described that contribute information about characteristics of the comorbid phenotype. Second, studies related to procedures directed toward evaluation and intervention in this problem are analyzed. The review carried out does not make it possible to extract definitive results on the exact nature of ADHD and RD comorbidity or, even less, reach conclusions about its causes. However, the literature-based evidence shows a cognitive profile of ADHD+RD characterized by failure of various functions that can produce more severe functional deficits and worse neuropsychological, academic, and behavioral outcomes. Furthermore, the analysis of the set of results from the studies shows a limited efficacy of pharmacological and psychopedagogical treatments, and highlights the need for continued research on this topic. From a clinical and educational standpoint, the conclusions derived from this review underline the importance of performing an exhaustive evaluation of children and adolescents with symptoms of ADHD and/or RD, in order to be able to plan interventions with greater possibilities of success in each cas

The XMM-Newton survey of the Small Magellanic Cloud: XMMUJ005011.2-730026 = SXP214, a Be/X-ray binary pulsar

In the course of the XMM-Newton survey of the Small Magellanic Cloud (SMC), a region to the east of the emission nebula N19 was observed in November 2009. To search for new candidates for high mass X-ray binaries the EPIC PN and MOS data of the detected point sources were investigated and their spectral and temporal characteristics identified. A new transient (XMMUJ005011.2-730026= SXP214) with a pulse period of 214.05 s was discovered; the source had a hard X-ray spectrum with power-law index of ~0.65. The accurate X-ray source location permits the identification of the X-ray source with a ~15th magnitude Be star, thereby confirming this system as a new Be/X-ray binary.Comment: 8 pages 11 figures. Accepted for publication in MNRA