156 research outputs found
Mechanisms for photon sorting based on slit-groove arrays
Mechanisms for one-dimensional photon sorting are theoretically studied in
the framework of a couple mode method. The considered system is a nanopatterned
structure composed of two different pixels drilled on the surface of a thin
gold layer. Each pixel consists of a slit-groove array designed to squeeze a
large fraction of the incident light into the central slit. The Double-Pixel is
optimized to resolve two different frequencies in the near infrared. This
system shows a high transmission efficiency and a small crosstalk. Its response
is found to strongly depend on the effective area shared by overlapping pixels.
Three different regimes for the process of photon sorting are identified and
the main physical trends underneath in such regimes are unveiled. Optimal
efficiencies for the photon sorting are obtained for a moderate number of
grooves that overlap with grooves of the neighbor pixel. Results could be
applied to optical and infrared detectors.Comment: 12 pages, 4 figure
Transmittance of a subwavelength aperture flanked by a finite groove array \\ placed near the focus of a conventional lens
One-dimensional light harvesting structures illuminated by a conventional
lens are studied in this paper. Our theoretical study shows that high
transmission efficiencies are obtained when the structure is placed near the
focal plane of the lens. The considered structure is a finite slit-groove array
(SGA) with a given number of grooves that are symmetrically distributed with
respect to a central slit. The SGA is nano-patterned on an opaque metallic
film. It is found that a total transmittance of 80% is achieved even for a
single slit when (i) Fabry-Perot like modes are excited inside the slit and
(ii) the effective cross section of the aperture becomes of the order of the
full width at half maximum of the incident beam. A further enhancement of 8% is
produced by the groove array. The optimal geometry for the groove array
consists of a moderate number of grooves () at either side of the
slit, separated by a distance of half the incident wavelength .
Grooves should be deeper (with depth ) than those typically
reported for plane wave illumination in order to increase their individual
scattering cross section.Comment: 7 pages, 6 figure
f [N pi N]: from quarks to the pion derivative coupling
We study the N pi N coupling, in the framework of a QCD-inspired confining
Nambu-Jona-Lasinio model. A simple relativistic confining and instantaneous
quark model is reviewed. The Salpeter equation for the nucleon and the boosted
pion is solved. The f [n pi n] and f[n pi Delta] couplings are calculated and
they turn out to be reasonably good. The sensibility of f[n pi n] and f[n pi
Delta] to confinement, chiral symmetry breaking and Lorentz invariance is
briefly discussed.Comment: 30 pages in LaTex RevTex, 6 postscript figure
Functional analyses of a novel splice variant in the CHD7 gene, found by next generation sequencing, Confirm Its pathogenicity in a Spanish patient and diagnose him with CHARGE syndrome
Mutations in CHD7 have been shown to be a major cause of CHARGE syndrome, which presents many symptoms and features common to other syndromes making its diagnosis difficult. Next generation sequencing (NGS) of a panel of intellectual disability related genes was performed in an adult patient without molecular diagnosis. A splice donor variant in CHD7 (c.5665 + 1G > T) was identified. To study its potential pathogenicity, exons and flanking intronic sequences were amplified from patient DNA and cloned into the pSAD® splicing vector. HeLa cells were transfected with this construct and a wild-type minigene and functional analysis were performed. The construct with the c.5665 + 1G > T variant produced an aberrant transcript with an insert of 63 nucleotides of intron 28 creating a premature termination codon (TAG) 25 nucleotides downstream. This would lead to the insertion of 8 new amino acids and therefore a truncated 1896 amino acid protein. As a result of this, the patient was diagnosed with CHARGE syndrome. Functional analyses underline their usefulness for studying the pathogenicity of variants found by NGS and therefore its application to accurately diagnose patients.This work was funded by Jesús de Gangoiti Barrera Foundation (FJGB15/005). The EAV laboratory is funded by projects of the Spanish Ministry of Economy and Competitiveness, National Plan for R & D 2013–2016, ISCIII (FIS: PI13/01749) co-financed by FEDER from Regional Development European Funds (European Union) and the project CSI090U14 of the Regional ministry of Education (ORDER EDU/122/2014) (Castilla y León, Spain). This study made use of data generated by the UK10K Project. Funding for the UK10K Project was provided by the Wellcome Trust under award WT091310.Peer reviewe
Repulsive Core of NN S-Wave Scattering in a Quark Model with a Condensed Vacuum
We work in a chiral invariant quark model, with a condensed vacuum,
characterized by only one parameter. Bound state equations for the nucleon and
Delta are solved in order to obtain an updated value of their radii and masses.
Nucleon-nucleon S-Wave scattering is studied in the RGM framework both for
isospin T=1 and T=0. The phase shifts are calculated and an equivalent local
potential, which is consistent with K-N scattering, is derived. The result is a
reasonable microscopic short range repulsion in the nucleon-nucleon
interaction.Comment: 23 pages in latex revtex, 4 Postscript figure
Optimal light harvesting structures at optical and infrared frequencies
One-dimensional light harvesting structures with a realistic geometry
nano-patterned on an opaque metallic film are optimized to render high
transmission efficiencies at optical and infrared frequencies. Simple design
rules are developed for the particular case of a slit-groove array with a given
number of grooves that are symmetrically distributed with respect to a central
slit. These rules take advantage of the hybridization of Fabry-Perot modes in
the slit and surface modes of the corrugated metal surface. Same design rules
apply for optical and infrared frequencies. The parameter space of the groove
array is also examined with a conjugate gradient optimization algorithm that
used as a seed the geometries optimized following physical intuition. Both
uniform and nonuniform groove arrays are considered. The largest transmission
enhancement, with respect to a uniform array, is obtained for a chirped groove
profile. Such enhancement is a function of the wavelength. It decreases from
39% in the optical part of the spectrum to 15% at the long wavelength infrared.Comment: 13 pages, 5 figure
Non-alcoholic fatty liver in hereditary fructose intolerance
Background: Non-alcoholic fatty liver disease (NAFLD) is characterized by fat accumulation affecting >5% of the liver volume that is not explained by alcohol abuse. It is known that fructose gives rise to NAFLD and it has been recently described that the ingestion of fructose in low amounts in aldolase B deficient mice is associated with the development of fatty liver. Therefore, it is reasonable that patients with HFI (Hereditary Fructose Intolerance) present fatty liver at diagnosis, but its prevalence in patients treated and with adequate follow-up is not well documented in the literature. The aim of this study is to analyze the association between HFI and NAFLD in treated patients.
Methods: A cross-sectional observational study was conducted. The population comprised 16 genetically diagnosed HFI patients aged from 3 years to 48 and in dietary treatment of fructose, sorbitol and sacarose exclusion at least for two years. Blood samples were obtained for analytical studies and anthropometric measurements of each patient were performed.
Results: Patients presented a Body Mass Index (BMI) of 17.9 ± 2.9 kg/m 2 . The HOMA index and Quick index were in normal range for our population. The S-adenosyl-methionine (SAM)/S-adenosyl-L-homocysteine (SAH) ratio was increased in the patients in whom this analysis was performed. By imaging techniques it was observed that 9 of the 16 patients presented fatty liver (7 by hepatic MRI). Of these 9 patients, only 3 presented hepatomegaly. 7 of 9 patients affected by the c.448G > C mutation had fatty infiltration, of which three of them presented in addition hepatomegaly.
Conclusions: There is a high prevalence of fatty liver in HFI patients and it is not related to obesity and insulin resistance. The diagnosis of fatty liver in HFI patients and, above all, the identification of new therapeutic approaches, can positively impact the quality of life of these patients
Clinical implication of FMR1 intermediate alleles in a Spanish population
FMR1 premutation carriers (55-200 CGGs) are at risk of developing Fragile X-associated primary ovarian insufficiency as well as Fragile X-associated tremor/ataxia syndrome. FMR1 premutation alleles are also associated with a variety of disorders, including psychiatric, developmental, and neurological problems. However, there is a major concern regarding clinical implications of smaller CGG expansions known as intermediate alleles (IA) or gray zone alleles (45-54 CGG). Although several studies have hypothesized that IA may be involved in the etiology of FMR1 premutation associated phenotypes, this association still remains unclear. The aim of this study was to provide new data on the clinical implications of IA. We reviewed a total of 17 011 individuals: 1142 with primary ovarian insufficiency, 478 with movement disorders, 14 006 with neurodevelopmental disorders and 1385 controls. Similar IA frequencies were detected in all the cases and controls (cases 1.20% vs controls 1.39%, P =.427). When comparing the allelic frequencies of IA = 50CGGs, a greater, albeit not statistically significant, number of alleles were detected in all the cohorts of patients. Therefore, IA below 50 CGGs should not be considered as risk factors for FMR1 premutation-associated phenotypes, at least in our population. However, the clinical implication of IA = 50CGGs remains to be further elucidated
Riesgo sísmico, geotécnico y estructural. El caso de estudio de los edificios San Jerónimo de Yuste en Bogotá
San Jerónimo de Yuste buildings are located in Bogotá, on sloping ground, in the foothills of the city. These buildings were built between 2008 and 2011 by the company BIO Construcciones, as part of a broader development project promoted by the family compensation fund Compensar. During the months of May and June 2013 the slope suffered both vertical and horizontal displacements that visibly damaged two of the buildings, which were then evacuated. This paper presents the studies conducted by the Architecture and Engineering Schools at Universidad de los Andes, in order to determine the causes that led to movement, estimate the safety factor and propose interventions at the geotechnical and structural levels which would allow the recovery of the affected buildings.El conjunto residencial San Jerónimo de Yuste se encuentra ubicado en Bogotá, en un terreno inclinado en el pie de monte de los cerros orientales de la ciudad. Fue construido entre 2008 y 2011, como parte de un proyecto de urbanización promovido por la caja de compensación familiar Compensar. Durante mayo y junio de 2013 el terreno presentó desplazamientos tanto verticales como horizontales que generaron daños visibles en las estructuras y motivaron la evacuación de dos de las seis torres que conforman el conjunto. El presente trabajo presenta los resultados de la investigación que llevaron a cabo los grupos de investigación de las facultades de Arquitectura e Ingeniería de la Universidad de los Andes para determinar las causas que condujeron al evento de desplazamiento de la estructura debidas al movimiento del terreno, estimar el coeficiente de seguridad actual y proponer intervenciones geotécnicas y estructurales que permitan recuperar la edificación
Homestead food production model contributes to improved household food security and nutrition status of young children and women in poor populations
Micronutrient malnutrition is a serious public health problem among women and children in Bangladesh, Cambodia, Nepal and the Philippines. Helen Keller International has been implementing homestead food production (HFP) programs (coupled with nutrition education) in these countries to increase and ensure year-round availability and intake of micronutrient-rich foods in poor households, particularly among women and children. Between 2003 and 2007, the HFP program was implemented among ~30,000 households in these four countries. Data collected from representative samples taken for evaluations of HFP programs in these countries illustrated the benefit of the program for households. Data were collected through interviews with households in villages that had the HFP program and from control households in non-HFP program villages. Blood samples collected from ~1000 children aged 6-59 months and ~1200 non-pregnant women before and after program implementation were analyzed for hemoglobin. The review showed that the HFP program significantly improved dietary diversification. The combined data from all four countries showed improved animal food consumption among program households, with liver consumption increasing from 24% at baseline to 46% at endline and the median number of eggs consumed by families per week increasing from 2 to 5. The sale of HFP products also improved household income. Anemia prevalence among children in program households decreased in all the countries; however, the decrease was only significant in Bangladesh and the Philippines. Although anemia prevalence also decreased among control households in three countries, the magnitude of change was higher in program households compared with control households.Les carences en micronutriments représentent un grave problème de santé publique chez les femmes et les enfants au Bangladesh, au Cambodge, au Népal et aux Philippines. Helen Keller International met en œuvre dans ces pays un programme de production alimentaire en exploitations familiales (homestead food production - HFP) associé à une éducation à l'alimentation afin d’augmenter et de garantir la disponibilité et la consommation d'aliments riches en micronutriments tout au long de l'année dans les foyers pauvres, et plus particulièrement chez les femmes et les enfants. Entre 2003 et 2007, le programme HFP a été mis en œuvre dans environ 30 000 foyers de ces quatre pays. Les données fournies par les échantillons représentatifs utilisés pour l'évaluation de ce programme mettent en évidence les bénéfices qu'il représente pour les familles. Ces données sont le résultat des entretiens conduits avec des familles appartenant à des villages participant au programme HFP, ainsi qu’avec des familles de contrôle dans des villages non concernés par le programme. Des analyses de l’hémoglobine ont été réalisées sur des échantillons sanguins prélevés avant et après la mise en œuvre du programme sur environ 1 000 enfants âgés de 6 à 59 mois et environ 1 200 femmes (non enceintes). L’évaluation du programme HFP a montré qu’il avait amélioré significativement la diversification alimentaire. Les données combinées des quatre pays montrent une amélioration de la consommation de produits d’origine animale chez les familles du programme. La consommation de foie est passée de 24 % à 46 %, et le nombre médian d’œufs consommés par semaine et par famille est passé de 2 à 5. La vente des produits issus du programme HFP a également amélioré les revenus de ces foyers. La prévalence de l’anémie chez les enfants participant au programme a diminué dans tous les pays. Cette diminution n'était cependant significative qu'au Bangladesh et aux Philippines. Bien que, dans trois pays, la prévalence de l’anémie ait également diminué chez les familles de contrôle, la différence était plus grande chez les familles participant au programme en comparaison avec les familles de contrôle.La malnutrición en micronutrientes es un problema de salud pública serio entre las mujeres y los niños en Bangladesh, Camboya, Nepal y Filipinas. En estos países Helen Keller International ha implementado programas de producción de alimentos en casa (PAC), conjuntamente con una educación en nutrición, para aumentar y asegurar la disponibilidad y el consumo todo el año de alimentos ricos en micronutrientes en hogares desfavorecidos, en particular entre las mujeres y los niños. Entre 2003 y 2007, el programa PAC fue aplicado en unos 30.000 hogares en estos cuatro países. Los datos obtenidos de las muestras representativas tomadas para la evaluación de los programas PAC en dichos países mostraron los beneficios del programa para los hogares. Los datos fueron recogidos a través de entrevistas con hogares en los pueblos en los que se aplicó el programa PAC y con hogares de control en pueblos sin el programa PAC. Antes y después de la implementación del programa, se tomaron muestras de sangre de unos 1000 niños entre 6 y 59 meses de edad y de unas 1200 mujeres no embarazadas; dichas muestras fueron analizadas para ver la hemoglobina. El estudio revela que el programa PAC mejoró de manera significativa la diversificación en la dieta. Los datos combinados de los cuatro países mostraron una mejoría en el consumo de alimentos de origen animal entre los hogares afiliados al programa, con un aumento del consumo de hígado de 24 % al comienzo a 46 % al final, y un aumento de 2 a 5 del número medio de huevos consumidos por familia y por semana. La venta de productos PAC también mejoró los ingresos del hogar. La prevalencia de anemia en los niños de hogares afiliados al programa disminuyó en todos los países; sin embargo, la disminución sólo fue significativa en Bangladesh y Filipinas. Aunque la prevalencia de anemia también disminuyó entre los hogares de control en tres países, la magnitud del cambio fue mayor en hogares del programa que en hogares de control
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