Growth of Low-Density Vertical Quantum Dot Molecules with Control in Energy Emission

In this work, we present results on the formation of vertical molecule structures formed by two vertically aligned InAs quantum dots (QD) in which a deliberate control of energy emission is achieved. The emission energy of the first layer of QD forming the molecule can be tuned by the deposition of controlled amounts of InAs at a nanohole template formed by GaAs droplet epitaxy. The QD of the second layer are formed directly on top of the buried ones by a strain-driven process. In this way, either symmetric or asymmetric vertically coupled structures can be obtained. As a characteristic when using a droplet epitaxy patterning process, the density of quantum dot molecules finally obtained is low enough (2 × 108 cm−2) to permit their integration as active elements in advanced photonic devices where spectroscopic studies at the single nanostructure level are required

Anatomical and functional brain approach along short abrupt changes in G-levels

To conduct experiments under abrupt changes in g-levels, a single-engine aerobatic aircraft has been used, providing 6-8 seconds of reduced gravity, preceded and followed by 5-7 seconds of hypergravity periods. Due to the specific conditions of the flight and previous findings [1], the hypothesis of the present work lies on the idea that some sensory inputs could have a notorious effect on brain final responses when gravity is altered. Therefore, this study focuses on the evaluation of such hypothesis, based on the analysis of the evolution in time of intracranial activity of limbic, visual and auditory cortices. Five subjects (N=5, age 41¿14 years) have flown in parabolic flight with their eyes both open and closed. Electroencephalogram signals were recorded with an Emotive Epoc headset, synchronized with a triaxial accelerometer. The intracranial brain bioelectric activity (standardized current density) throughout the parabola, was calculated by applying Standard Low Resolution Brain Electromagnetic Tomography, and it was analyzed for the limbic, visual and auditory cortices. Intracranial activity of the Temporal, Parietal and Occipital lobes were carried out as well in order to compare the different periods/phases of the flight. Results detected a lower brain activity during the hypogravity phase in all lobes and cortices, only in the case of open eyes. The bioelectrical brain activity along the parabola showed similar patterns in all lobes and cortices, when visual inputs are highlighted. Suppressing the sight, two major behaviors were detected in brain activity: one for temporal lobe and auditory cortex, and second one for the rest of the lobes and visual cortex. It Seemed that, flying with closed eyes, other sensory stimuli were enhanced, in this case the auditory cortex. To confirm the validity of the results two-way ANOVA (factors lobe/phases) and Fisher post hoc test have been applied on mean intracranial activity values in all cases. Spectral entropy evolution in time has been considered as a fast indicator of the sudden extracranial brain activity variation during short g-changes. For open eyes, spectral entropy values indicated a slight decrease at the onset of the hypogravity phase, whereas in case of closed eyes, this change was detected in the last seconds of the parabola, even though these fluctuations were statistically non-significant. Results suggest that some of the sensory inputs can indeed have an impact on brain final response, when gravity conditions are altered.Peer ReviewedPostprint (published version

Charge control in laterally coupled double quantum dots

We investigate the electronic and optical properties of InAs double quantum dots grown on GaAs (001) and laterally aligned along the [110] crystal direction. The emission spectrum has been investigated as a function of a lateral electric field applied along the quantum dot pair mutual axis. The number of confined electrons can be controlled with the external bias leading to sharp energy shifts which we use to identify the emission from neutral and charged exciton complexes. Quantum tunnelling of these electrons is proposed to explain the reversed ordering of the trion emission lines as compared to that of excitons in our system.Comment: 4 pages, 4 figures submitted to PRB Rapid Com

Surface Localization of Buried III–V Semiconductor Nanostructures

In this work, we study the top surface localization of InAs quantum dots once capped by a GaAs layer grown by molecular beam epitaxy. At the used growth conditions, the underneath nanostructures are revealed at the top surface as mounding features that match their density with independence of the cap layer thickness explored (from 25 to 100 nm). The correspondence between these mounds and the buried nanostructures is confirmed by posterior selective strain-driven formation of new nanostructures on top of them, when the distance between the buried and the superficial nanostructures is short enough (d = 25 nm)

Detección específica de Arcobacter Butzleri en carne de pollo mediante una técnica de PCR

En este trabajo se describe el desarrollo de una técnica de PCR para la detección específica de Arcobacter butzleri en carne fresca de pollo empleando cebadores específicos de especie diseñados en gen 16S ARN ribosómico. Los cebadores seleccionados amplifican un fragmento de 195 pb en A. butzleri, sin producir señal de amplificación en otras especies de Arcobacter, Campylobacter, Helicobacter, ni en otros microorganismos presentes en los alimentos. La técnica de PCR se ha aplicado al análisis de 42 muestras comerciales de carne fresca de pollo adquiridas en diversos comercios minoristas. Tras un pre enriquecimiento selectivo durante 18 h a 30ºC, A. butzleri se detectó en un 85,7% de las muestras analizadas. Se observó una total concordancia entre los resultados obtenidos por PCR y el método convencional de recuento en placas de agar selectivo.A PCR technique was developed for the specific detection of Arcobacter butzleri in fresh chicken meat using species-specific primers designed on the 16S ribosomal ARN gene. The selected primers amplify a 195 bp fragment from A. butzleri whereas no PCR product is generated for other Arcobacter, Campylobacter, Helicobacter species, and other food bacteria. The PCR technique was used to screen 42 retail-purchased chicken samples for the presence of A. butzleri. Following a selective enrichment for 18 h at 30ºC, A butzleri was detected in 85.7% of the analyzed samples, showing a total concordance between the PCR results and the conventional selective plating method

Galaxy interactions II: High density environments

With the aim to assess the role of dense environments in galaxy interactions, properties we present an analysis of close galaxy pairs in groups and clusters, obtained from the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7). We identified pairs that reside in groups by cross-correlating the total galaxy pair catalogue with the SDSS-DR7 group catalogue from Zapata et al. (2009). We classify pair galaxies according to the intensity of interaction. We analysed the effect of high density environments on different classes of galaxy-galaxy interactions and we have also studied the impact of the group global environment on pair galaxies. We find that galaxy pairs are more concentrated towards the group centres with respect to the other group galaxy members, and disturbed pairs show a preference to contain the brightest galaxy in the groups. The color-magnitude relation exhibits significant differences between pair galaxies and the control sample, consisting in color tails with a clear excess of extremely blue and red galaxies for merging systems. In addition, pair galaxies show a significant excess of young stellar populations with respect to galaxies in the control sample; this finding suggests that, in dense environments, strong interactions produce an important effect in modifying galaxy properties. We find that the fraction of star forming galaxies decreases toward the group centre; however, galaxy pairs show a more efficient star formation activity than galaxies without a close companion. We have also found that pair galaxies prefer groups with low density global environments with respect to galaxies of the corresponding control sample. Blue, young stellar population galaxies prefer groups within low density global environments.Comment: 10 pages, 11 figures, accepted for publication in A&

Dislipidemias in Patients with Cardiopathy Isquemica

The dislipidemias are a risk factor well recognized of the cardiovascular diseases and constitute a problem of public health. A descriptive study in 150 patient elders of 30 years with diagnosis of Izquemic Cardiopathyes accomplished itself for the sake of identifying dislipidemias in patients of high cardiovascular risk that they helped the high-technology General Medical Center state James Mariño Aragua, at the Republic Bolivariana of Venezuela, that you constituted the sign of study from October 2011 to October 2012. They used quantitative and qualitative variables like weight, age, sex, pathological personal background, risk factors cardiovascular associates, seric levels of total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol VLDL cholesterol. 63 percent of patients with dislipidemias were detected, being hypercholesterolemia the more alteration frequently found. The ages understood between 41 and 60 years evidenced the bigger frequency

Hypoxic exposure as a means of increasing sporting performance: fact or fiction?

Las crecientes exigencias del deporte de élite han propiciado la continua investigación de diversos métodos para aumentar el rendimiento deportivo de los deportistas. Uno de los que más se ha hablado en los últimos años, especialmente en los deportes de resistencia, es el entrenamiento en altitud o exposición hipóxica. No obstante, a pesar de la popularidad que ha cobrado entre atletas y entrenadores de todo el mundo, existe una gran controversia sobre sus supuestas bondades. De esta forma, el objetivo de esta revisión es tratar de clarificar el papel de la exposición hipóxica en el aumento del rendimiento deportivo, analizando las distintas metodologías, herramientas e investigaciones al respecto. Se concluye que la exposición hipóxica carece en la actualidad de suficientes evidencias científicas que validen su efectividad, pues los resultados de la literatura son contradictorios.The increasing demands of elite sports have led to continuing research into various methods for improving the sporting performance of their participants. One of the most widely discussed in the past few years, especially in the field of endurance sports, is altitude training, or hypoxic exposure. However, despite its increasing popularity amongst athletes and coaches worldwide, a great deal of controversy remains regarding its supposed benefits. As such, the aim of this review was to attempt to clarify the role of hypoxic exposure on improved sporting performance by analysing the various methodologies, tools and research available. The key conclusion is that hypoxic exposure currently lacks sufficient scientific evidence to validate its efficacy as literature results tend to be contradictory