291 research outputs found

    Impacts of climate change on erosion in humid and dry Mediterranean regions of Portugal

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    Soils in the Mediterranean regions of Europe are often vulnerable to soil erosion, due to a combination of annual plant cover cycles, centuries of human use, the concentration of rainstorms in a short period of the year, and other factors. Climate change could bring about a warmer and drier climate, limiting vegetation growth while bringing heavier storms during winter. This could eventually lead to higher risks of soil losses and the consequential problems of land degradation and desertification. Project ERLAND, which began in 2009, is assessing these risks for two Mediterranean research catchments in Portugal, with four main goals: (i) collect data to understand hydrological and erosion processes in representative catchments; (ii) use this data to parameterize the SWAT eco-hydrological and erosion model as accurately as possible; (iii) use future socio-economic scenarios to estimate both impacts on climate change and on future land-use practices; and (iv) apply the SWAT model for these scenarios and estimate the consequences for soil erosion rates. The Macieira catchment is in a wet Mediterranean climate region, with high rainfall (c. 1300 mm.y-1) but a distinct summer dry season; erosion processes are associated with periods of sparse cover in autumn in fields with a pasture-corn rotation, but also with forest plantations after clear-cutting and especially after forest fires. The occurrence of a forest fire inside the catchment in 2011 allowed an analysis of the role played by this kind of disturbances on soil erosion. Climate change could bring less erosive rainfall events, but an increase in fire frequency, and therefore a potential shift of erosion from agriculture to forest land-uses. The Guadalupe catchment has a dry Mediterranean climate (rainfall of c. 550 mm.y-1); erosion processes occur mostly in permanent crops (olive trees) and winter cereal fields. Climate change could bring a concentration of rainfall in winter, as well as an increase in the area with permanent crops, bringing additional exposure to erosion. This communication presents the overall concept and work performed in project ERLAND, including an assessment of the large impact of the fire in the wet catchment (Macieira) on soil erosion rates, where results indicate that soil losses after soil preparation for forest replanting might be equivalent, in long-term, to soil losses in agricultural fields. It also provides preliminary results for the impacts of climate change on soil erosion in the dry catchment (Guadalupe), which indicate a potential increase of soil loss rates by 2100 in the most vulnerable areas (winter cereal fields and olive groves) due to a higher concentration of rainfall in winter. The foreseen replacement of some winter cereals and pastures by sunflower cultivation for biofuel production could also lead to important changes in erosion rates

    An extraordinary chiral exchange-bias phenomenon: Engineering the sign of the bias field in orthogonal bilayers by a magnetically switchable response mechanism

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    [EN] Isothermal tuning of both the magnitude and the sign of the bias field has been achieved by exploiting a new phenomenon in a system consisting of two orthogonally coupled films: SmCo (out-of-plane anisotropy)-CoFeB (in-plane anisotropy). This has been achieved by using the large dipolar magnetic field of the SmCo layer resulting in the pinning of one of the branches of the hysteresis loop (either the ascending or the descending branch) at a fixed field value while the second one is modulated along the field axis by varying the orientation of an externally applied magnetic field. This means the possibility of controlling the sign of the bias field in a manner not reported to date. Moreover, modulation of the bias field strength is possible by varying the thickness of a spacer between the SmCo and CoFeB layers. This study shows that the observed phenomena find their origin in the competition between the artificially induced anisotropies in both layers, resulting in a reversible chiral bias effect that allows the selection of the initial sign of the bias field by switching (upwards/downwards) the magnetization in the SmCo film.This research was supported by the Joint German-Spanish Actions Programme (DAAD and Fundación Universidad.es via Ref. 57050243), the Spanish Ministerio de Economía y Competitividad (MINECO) through “SIESPER” (MAT2011-25598) Project, and the Regional Government of Madrid through NANOMAGCOST (P2018/NMT-4321) project. D. S. acknowledges financial support from Xunta de Galicia under the postdoctoral program I2C Plan (Modalidade B) and the Strategic Grouping in Materials (AeMAT; grant No.ED431E2018/08). IMDEA Nanoscience is supported by the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D, MINECO [grant number SEV-2016-0686]Electronic supplementary information (ESI) available. See DOI: 10.1039/c9nr08852

    Inflammation, insulin resistance, and diabetes-mendelian randomization using CRP haplotypes points upstream

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    Background Raised C-reactive protein (CRP) is a risk factor for type 2 diabetes. According to the Mendelian randomization method, the association is likely to be causal if genetic variants that affect CRP level are associated with markers of diabetes development and diabetes. Our objective was to examine the nature of the association between CRP phenotype and diabetes development using CRP haplotypes as instrumental variables. Methods and Findings We genotyped three tagging SNPs (CRP + 2302G > A; CRP + 1444T > C; CRP + 4899T > G) in the CRP gene and measured serum CRP in 5,274 men and women at mean ages 49 and 61 y (Whitehall II Study). Homeostasis model assessment-insulin resistance (HOMA-IR) and hemoglobin A1c (HbA1c) were measured at age 61 y. Diabetes was ascertained by glucose tolerance test and self-report. Common major haplotypes were strongly associated with serum CRP levels, but unrelated to obesity, blood pressure, and socioeconomic position, which may confound the association between CRP and diabetes risk. Serum CRP was associated with these potential confounding factors. After adjustment for age and sex, baseline serum CRP was associated with incident diabetes (hazard ratio = 1.39 [95% confidence interval 1.29-1.51], HOMA-IR, and HbA1c, but the associations were considerably attenuated on adjustment for potential confounding factors. In contrast, CRP haplotypes were not associated with HOMA-IR or HbA1c (p=0.52-0.92). The associations of CRP with HOMA-IR and HbA1c were all null when examined using instrumental variables analysis, with genetic variants as the instrument for serum CRP. Instrumental variables estimates differed from the directly observed associations (p=0.007-0.11). Pooled analysis of CRP haplotypes and diabetes in Whitehall II and Northwick Park Heart Study II produced null findings (p=0.25-0.88). Analyses based on the Wellcome Trust Case Control Consortium (1,923 diabetes cases, 2,932 controls) using three SNPs in tight linkage disequilibrium with our tagging SNPs also demonstrated null associations. Conclusions Observed associations between serum CRP and insulin resistance, glycemia, and diabetes are likely to be noncausal. Inflammation may play a causal role via upstream effectors rather than the downstream marker CRP

    Distance-based emission factors from vehicle emission remote sensing measurements

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    Vehicle emission remote sensing has the potential to provide detailed emissions information at a highly disaggregated level owing to the ability to measure thousands of vehicles in a single day. Fundamentally, vehicle emission remote sensing provides a direct measure of the molar volume ratio of a pollutant to carbon dioxide, from which fuel-based emissions factors can readily be calculated. However, vehicle emissions are more commonly expressed in emission per unit distance travelled e.g. grams per km or mile. To express vehicle emission remote sensing data in this way requires an estimate of the fuel consumption at the time of the emission measurement. In this paper, an approach is developed based on vehicle specific power that uses commonly measured or easily obtainable vehicle information such as vehicle speed, acceleration and mass. We test the approach against 55 independent comprehensive PEMS measurements for Euro 5 and 6 gasoline and diesel vehicles over a wide range of driving conditions and find good agreement between the method and PEMS data. The method is applied to individual vehicle model types to quantify distance-based emission factors. The method will be appropriate for application to larger vehicle emission remote sensing databases, thus extending real-world distance-based vehicle emissions information

    Performance of prototypes for the ALICE electromagnetic calorimeter

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    The performance of prototypes for the ALICE electromagnetic sampling calorimeter has been studied in test beam measurements at FNAL and CERN. A 4×44\times4 array of final design modules showed an energy resolution of about 11% /E(GeV)\sqrt{E(\mathrm{GeV})} \oplus 1.7 % with a uniformity of the response to electrons of 1% and a good linearity in the energy range from 10 to 100 GeV. The electromagnetic shower position resolution was found to be described by 1.5 mm \oplus 5.3 mm /E(GeV)\sqrt{E \mathrm{(GeV)}}. For an electron identification efficiency of 90% a hadron rejection factor of >600>600 was obtained.Comment: 10 pages, 10 figure

    Improved FIFRELIN de-excitation model for neutrino applications

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    The precise modeling of the de-excitation of Gd isotopes is of great interest for experimental studies of neutrinos using Gd-loaded organic liquid scintillators. The FIFRELIN code was recently used within the purposes of the STEREO experiment for the modeling of the Gd de-excitation after neutron capture in order to achieve a good control of the detection efficiency. In this work, we report on the recent additions in the FIFRELIN de-excitation model with the purpose of enhancing further the de-excitation description. Experimental transition intensities from EGAF database are now included in the FIFRELIN cascades, in order to improve the description of the higher energy part of the spectrum. Furthermore, the angular correlations between {\gamma} rays are now implemented in FIFRELIN, to account for the relative anisotropies between them. In addition, conversion electrons are now treated more precisely in the whole spectrum range, while the subsequent emission of X rays is also accounted for. The impact of the aforementioned improvements in FIFRELIN is tested by simulating neutron captures in various positions inside the STEREO detector. A repository of up-to-date FIFRELIN simulations of the Gd isotopes is made available for the community, with the possibility of expanding for other isotopes which can be suitable for different applications.Comment: Corrected typos on author names on arXiv metadat

    El asiento de avería y el origen de la compañía privilegiada en España

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    El presente artículo analiza cómo la autonomía patrimonial del capital destinado a la organización de las flotas con América acabó adquiriendo la forma de una verdadera compañía privilegiada de comercio, antecedente directo de la actual sociedad anónima, cuando la Corona dejó por entero a los particulares la administración de la avería a través del sistema de asientos. Los paralelismos de los asientos con las compañías llegaron a ser tan grandes que los funcionarios a quienes el conde-duque de Olivares encomendó el estudio de las compañías extranjeras, con objeto de introducirlas en España, vieron en los asientos una verdadera compañía privilegiada.This paper analyses how the progressive autonomy of the capital used to arrange the treasure fleets from Seville to America derived in a real chartered company, a precedent of today’s joint-stock company, when the Crown finally privatised it through the asientos de avería. The parallelism among the asientos and the companies were so noticeable that the public officers appointed by the Count-Duke of Olivares to study the foreign companies couldn’t detect any difference between both institutions.Publicad
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