120 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
Mechanisms for photon sorting based on slit-groove arrays
Mechanisms for one-dimensional photon sorting are theoretically studied in the framework of a coupled-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 high transmission efficiencies and a small crosstalk. It is found that the response of the system strongly depends on the effective area shared by overlapping pixels. According to such degree of overlap, photon sorting can be achieved within three different regimes, which are discussed in detail. Optimal photon-sorting efficiencies are obtained for a moderate number of grooves that overlap with grooves of the neighbor pixel. These results could be applied to both optical and infrared detectors.The authors gratefully acknowledge financial support by European Projects EC FP7-ICT PLAISIR Project Ref. 247991, the Spanish Ministry of Science and Innovation project MAT2011-28581-C02-02, and the CUD project Ref. 2013-13.Peer Reviewe
Zooplankton variability at four monitoring sites of the Northeast Atlantic shelves differing in latitude and trophic status
Zooplankton abundance series (1999–2013) from the coastal sites of Bilbao 35 (B35), Urdaibai 35 (U35), Plymouth
L4 (L4) and Stonehaven (SH), in the Northeast Atlantic were compared to assess differences in the magnitude of
seasonal, interannual and residual scales of variability, and in patterns of seasonal and interannual variation in relation
to latitudinal location and trophic status. Results showed highest seasonal variability at SH consistent with its
northernmost location, highest interannual variability at U35 associated to an atypical event identified in 2012 in
the Bay of Biscay, and highest residual variability at U35 and B35 likely related to lower sampling frequency and
higher natural and anthropogenic stress. Interannual zooplankton variations were not coherent across sites, suggesting
the dominance of local influences over large scale environmental drivers. For most taxa the seasonal pattern
showed coherent differences across sites, the northward delay of the annual peak being the most common feature.
The between-site seasonal differences in spring–summer zooplankton taxa were related mainly to phytoplankton
biomass, in turn, related to differences in latitude or anthropogenic nutrient enrichment. The northward delay in
water cooling likely accounted for between-site seasonal differences in taxa that increase in the second half of
the year
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
Eu e a Física, 12
Livro de texto para a disciplina de Física do 12º ano, elaborado por uma equipa puridisciplinar de autores do Ensino Secundário e do Ensino Superior. Constituido por um manual com 3 partes, guia do professor, caderno de actividades e manual virtual do professor.Texbook for the Physics course of the 12th year, written by a multidisciplinar team of High School and University teachers. It includes a manual with three parts, a teacher's guide, activities notebook and virtual manual for the teacher
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
Zooplankton seasonality across a latitudinal gradient in the Northeast Atlantic Shelves Province
Zooplankton seasonality and its environmental drivers were studied at four coastal sites within the Northeast Atlantic Shelves Province (Bilbao35 (B35) and Urdaibai35 (U35) in the Bay of Biscay, Plymouth L4 (L4) in the English Channel and Stonehaven (SH) in the North Sea) using time series spanning 1999–2013. Seasonal community patterns were extracted at the level of broad zooplankton groups and copepod and cladoceran genera using redundancy analysis. Temperature was generally the environmental factor that explained most of the taxa seasonal variations at the four sites. However, between-site differences related to latitude and trophic status (i.e. from oligotrophic to mesotrophic) were observed in the seasonality of zooplankton community, mainly in the pattern of taxa that peaked in spring-summer as opposed to late autumn-winter zooplankton, which were linked primarily to differences in the seasonal pattern of phytoplankton. The percentage of taxa variations explained by environmental factors increased with latitude and trophic status likely related to the increase in the co-variation of temperature and chlorophyll a, as well as in the increase in regularity of the seasonal patterns of both temperature and chlorophyll a from south to north, and of chlorophyll a with trophic status. Cladocerans and cirripede larvae at B35 and U35, echinoderm larvae at L4 and decapod larvae at SH made the highest contribution to shape the main mode of seasonal pattern of zooplankton community, which showed a seasonal delay with latitude, as well as with the increase in trophic status
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
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
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