400 research outputs found

    Biofuel policy for the pursuit of multiple goals: The case of Washington State

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    Agricultural and Food Policy, Resource /Energy Economics and Policy,

    Immunonutrition as a potential strategy to prevent and cope with coronavirus disease (COVID-19)

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    In this article, a brief review of immunonutrition as a feasible alternative to modulating the immune system in defence of the SARS-CoV-2 that causes COVID-19 was presented. Immunonutrition is the nutritional practice that includes the necessary nutrients to modulate the activity of the immune system in health and disease. To date, studies are encouraging because they indicate that a good diet restores or improves the immune system's response to pathogens such as SARS-CoV-2. In addition, applying immunonutrition helps people recover with fewer sequelae after going through a serious infection in hospitalization and/or intensive care unit. Finally, it is suggested that immunonutrition be applied in conjunction with other good lifestyles and strictly following current health recommendations.RevisiĂłn por pare

    Polarization proximity effect in isolator crystal pairs

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    We experimentally studied the polarization dynamics (orientation and ellipticity) of near infrared light transmitted through magnetooptic Yttrium Iron Garnet crystal pairs using a modified balanced detection scheme. When the pair separation is in the sub-millimeter range, we observed a proximity effect in which the saturation field is reduced by up to 20%. 1D magnetostatic calculations suggest that the proximity effect originates from magnetostatic interactions between the dipole moments of the isolator crystals. This substantial reduction of the saturation field is potentially useful for the realization of low-power integrated magneto-optical devices.Comment: submitted to Optics Letter

    The impact of significant input of fine sediment on benthic fauna at tributary junctions: a case study of the Bermejo-Paraguay River confluence, Argentina

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    This study examines the morphological features, suspended sediment inputs and hydraulic conditions within a large river in association with ecological patterns before and after a tributary confluence. In order to examine these effects, the macroinvertebrate distributions from three reaches of the Paraguay and Bermejo Rivers (Paraguay-Argentina) are investigated. The Bermejo River is a tributary that supplies significant quantities of fine sediment to the Paraguay River, primarily in suspension. Two reaches were examined on the Paraguay River, upstream and downstream of the Bermejo River junction, with the third study reach located on the Bermejo River, upstream of the confluence with the Paraguay River. The results provide clear evidence that a significantly increased loading of fine sediment at a river confluence has effects on the distribution and potential movement of benthic invertebrates in the lotic environment by representing physical barriers at affected sites. These effects may be important at both local and regional scales, and such increases in suspended sediment (especially associated with anthropogenic change) may thus pose a major threat to ecosystem integrity that has been historically underestimated

    Freshwater plastic pollution:Recognizing research biases and identifying knowledge gaps

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    The overwhelming majority of research conducted to date on plastic pollution (all size fractions) has focused on marine ecosystems. In comparison, only a few studies provide evidence for the presence of plastic debris in freshwater environments. However, owing to the numerous differences between freshwater studies (including studied species and habitats, geographical locations, social and economic contexts, the type of data obtained and also the broad range of purposes), they show only fragments of the overall picture of freshwater plastic pollution. This highlights the lack of a holistic vision and evidences several knowledge gaps and data biases. Through a bibliometric analysis we identified such knowledge gaps, inconsistencies and survey trends of plastic pollution research within freshwater ecosystems. We conclude that there is a continued need to increase the field-data bases about plastics (all size fractions) in freshwater environments. This is particularly important to estimate river plastic emissions to the world´s oceans. Accordingly, data about macroplastics from most polluted and larger rivers are very scarce, although macroplastics represent a huge input in terms of plastics weight. In addition, submerged macroplastics may play an important role in transporting mismanaged plastic waste, however almost no studies exist. Although many of the most plastic polluted rivers are in Asia, only 14% of the reviewed studies were carried out in this continent (even though the major inland fisheries of the world are located in Asia´s rivers). The potential damage caused by macroplastics on a wide range of freshwater fauna is as yet undetermined, even though negative impacts have been well documented in similar marine species. We also noted a clear supremacy of microplastic studies over macroplastic ones, even though there is no reason to assume that freshwater ecosystems remain unaffected by macro-debris. Finally, we recommend focusing monitoring efforts in most polluted rivers worldwide, but particularly in countries with rapid economic development and poor waste management.Fil: Blettler, Martin Cesar Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Abrial, Elie. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Khan, Farhan R.. Roskilde University;Fil: Sivri, Nuket. Istanbul Üniversitesi;Fil: Espínola, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentin

    Mid-infrared optical parametric amplifier using silicon nanophotonic waveguides

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    All-optical signal processing is envisioned as an approach to dramatically decrease power consumption and speed up performance of next-generation optical telecommunications networks. Nonlinear optical effects, such as four-wave mixing (FWM) and parametric gain, have long been explored to realize all-optical functions in glass fibers. An alternative approach is to employ nanoscale engineering of silicon waveguides to enhance the optical nonlinearities by up to five orders of magnitude, enabling integrated chip-scale all-optical signal processing. Previously, strong two-photon absorption (TPA) of the telecom-band pump has been a fundamental and unavoidable obstacle, limiting parametric gain to values on the order of a few dB. Here we demonstrate a silicon nanophotonic optical parametric amplifier exhibiting gain as large as 25.4 dB, by operating the pump in the mid-IR near one-half the band-gap energy (E~0.55eV, lambda~2200nm), at which parasitic TPA-related absorption vanishes. This gain is high enough to compensate all insertion losses, resulting in 13 dB net off-chip amplification. Furthermore, dispersion engineering dramatically increases the gain bandwidth to more than 220 nm, all realized using an ultra-compact 4 mm silicon chip. Beyond its significant relevance to all-optical signal processing, the broadband parametric gain also facilitates the simultaneous generation of multiple on-chip mid-IR sources through cascaded FWM, covering a 500 nm spectral range. Together, these results provide a foundation for the construction of silicon-based room-temperature mid-IR light sources including tunable chip-scale parametric oscillators, optical frequency combs, and supercontinuum generators

    Modelling of photonic wire Bragg Gratings

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    Some important properties of photonic wire Bragg grating structures have been investigate. The design, obtained as a generalisation of the full-width gap grating, has been modelled using 3D finite-difference time-domain simulations. Different types of stop-band have been observed. The impact of the grating geometry on the lowest order (longest wavelength) stop-band has been investigated - and has identified deeply indented configurations where reduction of the stop-bandwidth and of the reflectivity occurred. Our computational results have been substantially validated by an experimental demonstration of the fundamental stop-band of photonic wire Bragg gratings fabricated on silicon-on-insulator material. The accuracy of two distinct 2D computational models based on the effective index method has also been studied - because of their inherently much greater rapidity and consequent utility for approximate initial designs. A 2D plan-view model has been found to reproduce a large part of the essential features of the spectral response of full 3D models

    Energy balance in a mango orchard in Northeast of Brazil.

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    The main objective of this research was the determination of the energy balance in a mango orchard

    Coeficiente de cultura e produtividade da mangueira irrigada.

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    Data of solar radiation, soil heat flux and dry and wet bulbs air temperature were used in the elaboration of theabove canopy energy balance based on Bowen ratio. Also, data soil humidity profiles were used in thedetermination of the soil water balance of a dripping irrigated seven years old mango orchard, cv. ?Tommy Atkins’.The field experiment was conducted in the irrigated perimeter of Bebedouro, in Petrolina-PE, Brazil (Latitude:09009`S, Longitude: 40022`W; altitude: 365.5m), in the years of 1998 and 1999. The obtained results indicatedthat, in the submedian San Francisco river region soil and climate conditions, the mango orchard waterconsumption, represented by the corp coefficient (Kc), doesn't stay constant throughout the productive cycle, but itvaries as a function of the days after flowering(DAF) according to the following equation: Kc = 0.36 + 0.009(DAF) – 4.0 x 10-5 (DAF)2, with r2 = 0.79

    Balanco hidrico no solo cultivado com mangueiras.

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    The experimental part of the present research was conducted in the irrigated perimeter of Bebedouro, Petrolina, PE,Brazil (Latitude: 09009`S, Longitude: 40022`W; altitude: 365.5m) in the years of 1998 and 1999, in a drippingirrigated plot area of 9,880 m2 seven years old mango orchard, cv. ?Tommy Atkins`, planted in a spacing of 5mbetween plants by 8m between arrays. This work evaluated the efficiency of the soil water balance for determiningthe evapotranspiraration throughout the mango orchard productive cycle. The errors analysis indicated that, for thesubmedian San Francisco river region soil and climate conditions, the soil water balance method for estimatingevapotranspiration should not be applied for periods lower than a week. Also, according to the obtained results, thesoil water balance method is only efficient in the estimates of the evapotranspiration of mango orchard whenconsidering the term regarding to the deep drainage or water ascent
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