5,463 research outputs found
Avaliação da ameaça de erosão hídrica na ilha da Madeira - Portugal
Na estimativa da erosão hídrica na ilha da Madeira aplicou-se a Equação de Wischmeier.
Recorreu-se a relações para estimar a erosividade (R); foi adequado o Índice Modificado de
Fournier e relação IMF/R. cartografada a erosividade os restantes parâmetros resultaram da
metodologia. IMF varia entre 81.0–465.0 mm. A equação R = 1.365 IMF1.408 estima a erosividade
anual precipitação, com dados de Funchal-Observatório, sul de Portugal e valores da literatura,
obtendo-se R ≈ 2 964 MJ mm h−1 ha−1 ano−1, variando entre 660- 8515. Erosão média é 28 t ha−1
ano−1, excedendo 100 em >4.9% da área. A ameaça de erosão adveio da divisão do volume de
solo dos horizontes mobilizáveis, pela erosão anual. O resultado -número de anos- que ocorre a
perda do solo de cobertura. Apesar do tempo para esgotamento do solo, ser >20 000 anos, a
ameaça de erosão, alta e muito alta, é relevante. Estas ameaças (depleção <100 anos) ocorrem
em 263 km2 (35.6%); na ameaça muito alta (depleção em <10 anos) a área é ≈40 km2 (5.4%).
Encostas com declives muito elevados estão associadas a ameaças altas (ou muito altas). Efetuouse a análise da precipitação 20 de Fevereiro, obtendo-se um período de retorno superior a 100
anos.info:eu-repo/semantics/publishedVersio
Many Body Problems with "Spin"-Related Contact Interactions
We study quantum mechanical systems with "spin"-related contact interactions
in one dimension. The boundary conditions describing the contact interactions
are dependent on the spin states of the particles. In particular we investigate
the integrability of -body systems with -interactions and point spin
couplings. Bethe ansatz solutions, bound states and scattering matrices are
explicitly given. The cases of generalized separated boundary condition and
some Hamiltonian operators corresponding to special spin related boundary
conditions are also discussed.Comment: 13 pages, Late
Sustainable Strategy Based on Induced Precipitation for the Purification of Phycobiliproteins
Phycobiliproteins are fluorescent proteins mainly produced by red macroalgae and cyanobacteria. These proteins, essential to the survival of these organisms, find application in many fields of interest, from medical, pharmaceutical, and cosmetic to food and textile industries. The biggest obstacle to their use is the lack of simple environmental and economical sustainable methodologies to obtain these proteins with high purity. In this work, a new purification process is proposed based on the induced precipitation of the target proteins followed by ultrafiltration. Purities of 89.5% of both phycobiliproteins and 87.3% of R-phycoerythrin were achieved using ammonium sulfate and poly(acrylic acid) sodium salts as precipitation agents (followed by an ultrafiltration step), while maintaining high recovery yields and protein structure stability. Environmental analysis performed to evaluate the proposed process shows that the carbon footprint for the proposed process is much lower than that reported for alternative methodology, and the economic analysis reveals the cost-effective character associated to its high performance. This work is a step toward more sustainable and effective methodologies/processes with high industrial potential
Generating Neutrino Mass in the 331 Model
A mechanism for generating small tree-level Majorana mass for neutrinos is
implemented in the 331 Model. No additional fermions or scalars need to be
added, and no mass scale greater than a few TeV is invoked.Comment: LaTex, 7 pages, no figures. Revised version to appear in Phys. Rev.
Effect of maternal Schistosoma mansoni infection and praziquantel treatment during pregnancy on Schistosoma mansoni infection and immune responsiveness among offspring at age five years.
INTRODUCTION: Offspring of Schistosoma mansoni-infected women in schistosomiasis-endemic areas may be sensitised in-utero. This may influence their immune responsiveness to schistosome infection and schistosomiasis-associated morbidity. Effects of praziquantel treatment of S. mansoni during pregnancy on risk of S. mansoni infection among offspring, and on their immune responsiveness when they become exposed to S. mansoni, are unknown. Here we examined effects of praziquantel treatment of S. mansoni during pregnancy on prevalence of S. mansoni and immune responsiveness among offspring at age five years. METHODS: In a trial in Uganda (ISRCTN32849447, http://www.controlled-trials.com/ISRCTN32849447/elliott), offspring of women treated with praziquantel or placebo during pregnancy were examined for S. mansoni infection and for cytokine and antibody responses to SWA and SEA, as well as for T cell expression of FoxP3, at age five years. RESULTS: Of the 1343 children examined, 32 (2.4%) had S. mansoni infection at age five years based on a single stool sample. Infection prevalence did not differ between children of treated or untreated mothers. Cytokine (IFNγ, IL-5, IL-10 and IL-13) and antibody (IgG1, Ig4 and IgE) responses to SWA and SEA, and FoxP3 expression, were higher among infected than uninfected children. Praziquantel treatment of S. mansoni during pregnancy had no effect on immune responses, with the exception of IL-10 responses to SWA, which was higher in offspring of women that received praziquantel during pregnancy than those who did not. CONCLUSION: We found no evidence that maternal S. mansoni infection and its treatment during pregnancy influence prevalence and intensity of S. mansoni infection or effector immune response to S. mansoni infection among offspring at age five years, but the observed effects on IL-10 responses to SWA suggest that maternal S. mansoni and its treatment during pregnancy may affect immunoregulatory responsiveness in childhood schistosomiasis. This might have implications for pathogenesis of the disease
Electrospun nanosized cellulose fibers using ionic liquids at room temperature
Aiming at replacing the noxious solvents commonly employed, ionic-liquid-based solvents have been recently explored as novel non-volatile and non-flammable media for the electrospinning of polymers. In this work, nanosized and biodegradable cellulose fibers were obtained by electrospinning at room temperature using a pure ionic liquid or a binary mixture of two selected ionic liquids. The electrospinning of 8 wt% cellulose in 1-ethyl-3-methylimidazolium acetate medium (a low viscosity and room temperature ionic liquid capable of efficiently dissolving cellulose) showed to produce electrospun fibers with average diameters within (470 ± 110) nm. With the goal of tailoring the surface tension of the spinning dope, a surface active ionic liquid was further added in a 0.10 : 0.90 mole fraction ratio. Electrospun cellulose fibers from the binary mixture composed of 1-ethyl-3-methylimidazolium acetate and 1-decyl-3-methylimidazolium chloride ionic liquids presented average diameters within (120 ± 55) nm. Scanning electron microscopy, X-ray diffraction analysis, nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric assays were used as core methods to evaluate the structural integrity, morphology and crystallinity of the raw, electrospun, and regenerated samples of cellulose. Moreover, the photoluminescence spectra of both raw and electrospun fibers were acquired, and compared, indicating that the cellulose emitting centers are not affected by the dissolution of cellulose in ionic liquids. Finally, the use of non-volatile solvents in electrospinning coupled to a water coagulation bath allows the recovery of the ionic fluid, and represents a step forward into the search of environmentally friendly alternatives to the conventional approaches
Same-sign dileptons as a signature for heavy Majorana neutrinos in hadron-hadron collisions
We discuss the possibility of same-sign dileptons as a signature for Majorana
neutrinos. The production mechanism is given by a single heavy neutrino
production and decay proton-proton -> l^{\pm} N X -> l^{\pm} l^{\pm} X'. Cross
section and distributions are presented for the LHC energies.Comment: 07 pages, LaTeX; to be published in Physics Letters
Development of policies and practices of social responsibility in Portuguese companies: implications of the SA8000 standard
Series: Management and Industrial EngineeringThis study aims to explore the implications of the SA8000 standard in the implementation of Corporate Social Responsibility (CSR) policies and practices in Portuguese companies. Although this is not a recent issue, it is a subject that has motivated a growing interest on the part of the business and academic community. CSR should be seen as a new business management model, which includes universal human values as well as ethical decisions that ensure the satisfaction of the interests and needs of all stakeholders and the community in general. Regarding the empirical aspect of this research, a qualitative approach was followed through the application of a semi-structured interview to certified and not certified companies by SA8000 standard, in order to understand possible disparities with regard to the implementation of CSR policies and practices. Although the certification is the guarantee of the commitment of the companies with the CSR, the truth is that this is seen by the companies as a form of differentiation in the market. In general terms, it can be concluded that the policies and practices of CSR do not differ in relation to certification, which means that all companies have the possibility of making a difference by being socially responsible.Delfina Gomes acknowledges that this study was conducted at the Research Center in Political Science (UID/CPO/0758/2019), University of Minho/University of Évora, and was supported by the Portuguese Foundation for Science and Technology and the Portuguese Ministry of Education and Science through national funds
Stillbirth at term: Does size really matter?
Placental dysfunction has a deleterious influence on fetal size and is associated with higher rates of perinatal morbidity and mortality. This association underpins the strategy of fetal size evaluation as a mechanism to identify placental dysfunction and prevent stillbirth. The optimal method of routine detection of small for gestational age (SGA) remains to be clarified with choices between estimation of symphyseal-fundal height versus routine third-trimester ultrasound, various formulae for fetal weight estimation by ultrasound, and the variable use of national, customized, or international fetal growth references. In addition to these controversies, the strategy for detecting SGA is further undermined by data demonstrating that the relationship between fetal size and adverse outcome weakens significantly with advancing gestation such that near term, the majority of stillbirths and adverse perinatal outcomes occur in normally sized fetuses. The use of maternal serum biochemical and Doppler parameters near term appears to be superior to fetal size in the identification of fetuses compromised by placental dysfunction and at increased risk of damage or demise. Multiparameter models and predictive algorithms using maternal risk factors, and biochemical and Doppler parameters have been developed, but need to be prospectively validated to demonstrate their effectiveness
Variations of training load, monotony, and strain and dose-response relationships with maximal aerobic speed, maximal oxygen uptake, and isokinetic strength in professional soccer players
This study aimed to identify variations in weekly training load, training monotony, and training strain across a 10-week period (during both, pre- and in-season phases); and to analyze the dose-response relationships between training markers and maximal aerobic speed (MAS), maximal oxygen uptake, and isokinetic strength. Twenty-seven professional soccer players (24.9±3.5 years old) were monitored across the 10-week period using global positioning system units. Players were also tested for maximal aerobic speed, maximal oxygen uptake, and isokinetic strength before and after 10 weeks of training. Large positive correlations were found between sum of training load and extension peak torque in the right lower limb (r = 0.57, 90%CI[0.15;0.82]) and the ratio agonist/antagonist in the right lower limb (r = 0.51, [0.06;0.78]). It was observed that loading measures fluctuated across the period of the study and that the load was meaningfully associated with changes in the fitness status of players. However, those magnitudes of correlations were small-to-large, suggesting that variations in fitness level cannot be exclusively explained by the accumulated load and loading profile
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