Critically coupled silicon Fabry-Perot photodetectors based on the internal photoemission effect at 1550 nm

In this paper, design, fabrication and characterization of an all-silicon photodetector (PD) at 1550 nm, have been reported. Our device is a surface-illuminated PD constituted by a Fabry-Perot microcavity incorporating a Cu/p-Si Schottky diode. Its absorption mechanism, based on the internal photoemission effect (IPE), has been enhanced by critical coupling condition. Our experimental findings prove a peak responsivity of 0.063 mA/W, which is the highest value obtained in a surface-illuminated IPE-based Si PD around 1550 nm. Finally, device capacitance measurements have been carried out demonstrating a capacitance < 5 pF which has the potential for GHz operation subject to a reduction of the series resistance of the ohmic contact

Asymmetric MSM sub-bandgap all-silicon photodetector with low dark current

Design, fabrication, and characterization of an asymmetric metal-semiconductor-metal photodetector, based on internal photoemission effect and integrated into a silicon-on-insulator waveguide, are reported. For this photodetector, a responsivity of 4.5 mA/W has been measured at 1550 nm, making it suitable for power monitoring applications. Because the absorbing metal is deposited strictly around the vertical output facet of the waveguide, a very small contact area of about 3 µm2 is obtained and a transit-time-limited bandwidth of about 1 GHz is demonstrated. Taking advantage of this small area and electrode asymmetry, a significant reduction in the dark current (2.2 nA at -21 V) is achieved. Interestingly, applying reverse voltage, the photodetector is able to tune its cut-off wavelength, extending its range of application into the MID infrared regime

Computational analysis of cooling dynamics in photonic-crystal-based thermal switches

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«The little things that run the world»: insetti a confronto attraverso modi di dire in latino, italiano, inglese

This paper explores the idiomatic expressions involving an insect as a source and a human being or their activities as a target across three languages – Latin, Italian, English. To scan their development through time we have opted for the use of three historic dictionaries as our reference, i.e. TLL, GDLI and OED. The analysis pursues several purposes: to determine and quantify the number of insects and idiomatic expressions synchronically and diachronically; to establish a comparison between the uses in the different languages; to discover common and culturally specific traits in how the three languages perceive the nature of insects, which have an impact on the sentiment regarding them; finally, to prove if there are anthropological, psychological and cognitive facets responsible for the sentiment entertained about insects

Mitochondrial DNA methylation is associated with Mediterranean diet adherence in a population of older adults with overweight and obesity.

AbstractIntroductionAdherence to the Mediterranean dietary pattern (MeDiet) and adiposity, respectively, decreases and increases the risk of multiple common age-related diseases through several mechanisms including inflammation, reactive oxygen species (ROS) production in the mitochondria, and DNA methylation. For example, adverse changes in platelets from obese and overweight adults include hyperaggregability and increased ROS. Since platelets are anuclear, their prothrombotic function is fully orchestrated by the mitochondria and the only DNA present is the mitochondrial DNA (mtDNA). In this study, we tested the hypothesis that MeDiet influences patterns of mtDNA methylation in platelets from older adults with greater adiposity.Material and methodsWe selected 134 participants with overweight or obesity (mean BMI = 35.5 ± 5.1 and age = 62 ± 10 years) from the "Susceptibility to particle health effects, miRNA and exosomes"(SPEHRE) Study. Dietary intake was assessed using a food frequency questionnaire and MeDiet adherence was calculated using the MeDiet Score described by Martínez-González et al.(2012). MtDNA was extracted from platelets, linearized, bisulfite converted and DNA methylation was quantified by pyrosequencing at 13 CpG in seven genes that encode for tRNAs (MT-TF and MT-TL1), regulatory regions (D-Loop and MT-OLR), and subunits of the electron-transport-chain (MT-CO1, MT-CO2, and MT-CO3).ResultsIn these participants, MeDiet score ranged from 3 to 12 (mean = 6.5), with higher scores reflecting greater MeDiet adherence. Regression analysis showed that higher MeDiet score was associated with lower D-loop (β = -0.031, P = 0.019) and higher MT-CO2 CpG1 (β = 0.040, P = 0.023) methylation. No associations were found between MeDiet Score and methylation level at MT-CO1(2 CpGs), MT-CO2(CpG2), MT-CO3(2 CpGs), MT-TL1(2 CpGs), MT-TF(CpG1), MT-OLR(3 CpGs).In addition, there was no association between mtDNA methylation and BMI.DiscussionThe D-loop is critical for mitochondrial function since it initiates mtDNA replication and transcription. Increased D-loop methylation has been associated with reduced mitochondrial functionality, and insulin resistance. Our results suggest that higher adherence to MeDiet lowers D-loop methylation which may protect against obesity-related comorbidities (e.g. insulin resistance).Higher MeDiet scores are associated with MT-CO2 CpG1 hypermethylation. MT-CO2 encodes for a subunit of the Cytochrome-C-oxidase, a highly regulated enzyme involved in the oxidative metabolism. MT-CO2 demethylation, induced by Valproic-Acid administration, has been reported to be associated with increased ROS production. Our results suggest a possible role of MeDiet in mitochondrial ROS regulation via methylation of MT-CO2.For the first time, we observed associations between MeDiet adherence and mtDNA methylation. Validation of these findings in independent cohorts is required

Producción de amaranto en un predio orgánico en la zona de Luján, Buenos Aires, Argentina

El amaranto (Amaranthus spp) es uno de los cultivos más antiguos de América, su siembra se ha incrementado por sus cualidades alimenticias (17% de proteínas, carbohidratos asimilables, vitaminas y minerales) y su capacidad de adaptabilidad a diversas condiciones climáticas. La planta y sus hojas pueden ser utilizadas como verduras; la planta madura y sus semillas pueden utilizarse como alimento para ganado. La realización de la experiencia surge a partir de la necesidad de los pequeños productores de encontrar alternativas productivas y del grupo de la Asignatura de la UNLu que realiza investigación en el tema. Se realizó un ensayo en un predio del distrito de San Andrés de Giles, se cultivaron 3 variedades; Amaranthus mantegazzianus cv Don Juan (Hortícola), Amaranthus cruentus cv Don Guien, Amaranthus cruentus cv Candil, para evaluar su comportamiento en condiciones a campo. En el año 2011 se realiza la primera experiencia con el seguimiento fenológico y comportamiento del cultivo y de los usos posibles que le dio el productor.Eje: B1 Sistemas de producción de base agroecológica (Relatos de experiencias)Facultad de Ciencias Agrarias y Forestale

Evaluación de actividad alimenticia de la fauna edáfica en manejos de suelos agroecológicos y convencionales.

El impacto de los diferentes sistemas de producción sobre el suelo se puede evaluar mediante bioindicadores como la técnica de lámina-cebo. Esta técnica cuantifica la actividad alimenticia de la fauna edáfica mediante una tira de PVC con orificios rellenos de un sustrato enriquecido que se entierra en el suelo. El objetivo de este trabajo fue evaluar esta técnica como bioindicador de la degradación biológica del suelo en manejos agroecológicos y convencionales. El estudio se realizó a campo y en condiciones controladas, no encontrando diferencias significativas. En el primer caso, podría asociarse al alto coeficiente de variación de los resultados. En el segundo caso, estaría asociado al breve periodo de aclimatación de las lombrices a los tratamientos contaminados y al efecto de adsorción de los herbicidas por la materia orgánica y arcilla del suelo. Se recomienda continuar con la evaluación de la técnica teniendo en cuenta estas consideraciones.The impacts of differents production system on soil can be assessed by biondicators as the bait-lamina test. This test cuantifies the soil fauna feeding activity through a PVC bait with holes filled with enriched substrate that is buried in the soil. The aim of this study was to assess this method as a bioindicator of biological soil degradation in agroecological and conventional agriculture. The field test contrasted agroecological and conventional agriculture. The impact of different herbicides combinations were sutudied under controlled condition. No significative differences were found. In the first case, it may be explained by a high variation coefficient. In the second case, it was probably associated with a brief aclimation period of earthworm to the contaminated treatments and with the adsorption effects of herbicides on organic matter and clays. It is recommended to continue the study of this method with all these considerations in mind.Eje A4: Ambiente, Naturaleza y AgroecologíaFacultad de Ciencias Agrarias y Forestale

Evaluación de actividad alimenticia de la fauna edáfica en manejos de suelos agroecológicos y convencionales.

El impacto de los diferentes sistemas de producción sobre el suelo se puede evaluar mediante bioindicadores como la técnica de lámina-cebo. Esta técnica cuantifica la actividad alimenticia de la fauna edáfica mediante una tira de PVC con orificios rellenos de un sustrato enriquecido que se entierra en el suelo. El objetivo de este trabajo fue evaluar esta técnica como bioindicador de la degradación biológica del suelo en manejos agroecológicos y convencionales. El estudio se realizó a campo y en condiciones controladas, no encontrando diferencias significativas. En el primer caso, podría asociarse al alto coeficiente de variación de los resultados. En el segundo caso, estaría asociado al breve periodo de aclimatación de las lombrices a los tratamientos contaminados y al efecto de adsorción de los herbicidas por la materia orgánica y arcilla del suelo. Se recomienda continuar con la evaluación de la técnica teniendo en cuenta estas consideraciones.The impacts of differents production system on soil can be assessed by biondicators as the bait-lamina test. This test cuantifies the soil fauna feeding activity through a PVC bait with holes filled with enriched substrate that is buried in the soil. The aim of this study was to assess this method as a bioindicator of biological soil degradation in agroecological and conventional agriculture. The field test contrasted agroecological and conventional agriculture. The impact of different herbicides combinations were sutudied under controlled condition. No significative differences were found. In the first case, it may be explained by a high variation coefficient. In the second case, it was probably associated with a brief aclimation period of earthworm to the contaminated treatments and with the adsorption effects of herbicides on organic matter and clays. It is recommended to continue the study of this method with all these considerations in mind.Eje A4: Ambiente, Naturaleza y AgroecologíaFacultad de Ciencias Agrarias y Forestale

Producción de amaranto en un predio orgánico en la zona de Luján, Buenos Aires, Argentina

El amaranto (Amaranthus spp) es uno de los cultivos más antiguos de América, su siembra se ha incrementado por sus cualidades alimenticias (17% de proteínas, carbohidratos asimilables, vitaminas y minerales) y su capacidad de adaptabilidad a diversas condiciones climáticas. La planta y sus hojas pueden ser utilizadas como verduras; la planta madura y sus semillas pueden utilizarse como alimento para ganado. La realización de la experiencia surge a partir de la necesidad de los pequeños productores de encontrar alternativas productivas y del grupo de la Asignatura de la UNLu que realiza investigación en el tema. Se realizó un ensayo en un predio del distrito de San Andrés de Giles, se cultivaron 3 variedades; Amaranthus mantegazzianus cv Don Juan (Hortícola), Amaranthus cruentus cv Don Guien, Amaranthus cruentus cv Candil, para evaluar su comportamiento en condiciones a campo. En el año 2011 se realiza la primera experiencia con el seguimiento fenológico y comportamiento del cultivo y de los usos posibles que le dio el productor.Eje: B1 Sistemas de producción de base agroecológica (Relatos de experiencias)Facultad de Ciencias Agrarias y Forestale