200 research outputs found

    Lixiviação de nitrato e sulfato ao longo do perfil de um latossolo vermelho que recebeu lodo de esgoto para fins agrícolas.

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    O lodo de esgoto proveniente do tratamento de efluentes industriais e domésticos tem sido aplicado em solos para fins agrícolas. Apesar dos efeitos benéficos da aplicação do lodo no solo, que envolvem o aumento da fertilidade do solo pelo fornecimento de nutrientes (N, Ca, P, S, e Zn) e pelo aumento da capacidade de troca catiônica (CTC) efetiva, há o risco potencial de poluição do solo e das águas superficiais e subterrâneas pelos constituintes do lodo. Com o objetivo de se avaliar a lixiviação de ânions e a poluição potencial de aqüíferos rasos, foram monitoradas as mobilidades do NO3 - e do SO4 2- ao longo do perfil de um Latossolo Vermelho distroférrico, que recebeu lodo de esgoto para fins agrícolas desde 1999, por meio da extração da solução do solo até 5m de profundidade ao longo de quatro anos, a partir do verão de 2003. Além disto foram avaliados os atributos do solo ao longo do perfil, incluindo a capacidade de troca de cátions e ânions, o ponto de efeito salino nulo e a mineralogia. O monitoramento ocorreu num experimento de aplicação de lodo no solo conduzido no campo experimental da EMBRAPA-Meio Ambiente em Jaguariúna-SP. O perfil apresentou balanço de cargas negativas até 2,5m de profundidade quando então foi observada a inversão de cargas e o balanço de cargas tornou-se positivo. Ao longo do monitoramento foram observados deslocamentos do sulfato até 2m de profundidade, com concentrações de 87 mg L-1 na solução e apesar da predominância de cargas positivas abaixo de 3m de profundidade, o nitrato se deslocou até 4m de profundidade, com concentrações de até 388 mg L-1 na solução do solo. A diluição da solução do solo, e a conseqüente diminuição da força iônica , ao longo do período de amostragem proporcionou a diminuição das cargas superficiais e a liberação do sulfato e do nitrato adsorvidos. Ao ser deslocado ao longo do perfil, o sulfato competiu com o nitrato pelos sítios de adsorção, o que resultou na sua lixiviação para maiores profundidades

    The combination of high-fat diet-induced obesity and chronic ulcerative colitis reciprocally exacerbates adipose tissue and colon inflammation

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    <p>Abstract</p> <p>Background</p> <p>This study evaluated the relationship between ulcerative colitis and obesity, which are both chronic diseases characterized by inflammation and increases in immune cells and pro-inflammatory cytokines.</p> <p>Methods</p> <p>Mice with chronic ulcerative colitis induced by 2 cycles of dextran sodium sulfate (DSS) in the first and fourth week of the experiment were fed a high-fat diet (HFD) to induce obesity by 8 weeks. The animals were divided into 4 groups (control, colitis, HFD and colitis + HFD).</p> <p>Results</p> <p>Obesity alone did not raise histopathology scores, but the combination of obesity and colitis worsened the scores in the colon compared to colitis group. Despite the reduction in weight gain, there was increased inflammatory infiltrate in both the colon and visceral adipose tissue of colitis + HFD mice due to increased infiltration of macrophages, neutrophils and lymphocytes. Intravital microscopy of VAT microvasculature showed an increase in leukocyte adhesion and rolling and overexpression of adhesion molecules compared to other groups. Moreover, circulating lymphocytes, monocytes and neutrophils in the spleen and cecal lymph nodes were increased in the colitis + HFD group.</p> <p>Conclusion</p> <p>Our results demonstrated the relationship between ulcerative colitis and obesity as aggravating factors for each disease, with increased inflammation in the colon and adipose tissue and systemic alterations observed in the spleen, lymph nodes and bloodstream.</p

    Langevin dynamics with dichotomous noise; direct simulation and applications

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    We consider the motion of a Brownian particle moving in a potential field and driven by dichotomous noise with exponential correlation. Traditionally, the analytic as well as the numerical treatments of the problem, in general, rely on Fokker-Planck description. We present a method for direct numerical simulation of dichotomous noise to solve the Langevin equation. The method is applied to calculate nonequilibrium fluctuation induced current in a symmetric periodic potential using asymmetric dichotomous noise and compared to Fokker-Planck-Master equation based algorithm for a range of parameter values. Our second application concerns the study of resonant activation over a fluctuating barrier.Comment: Accepted in Journal of Statistical Mechanics: Theory and Experimen

    Fishers' behaviour in response to the implementation of a marine protected area

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    Marine Protected Areas (MPAs) have been widely proposed as a fisheries management tool in addition to their conservation purposes. Despite this, few studies have satisfactorily assessed the dynamics of fishers' adaptations to the loss of fishing grounds. Here we used data from before, during and after the implementation of the management plan of a temperate Atlantic multiple-use MPA to examine the factors affecting the spatial and temporal distribution of different gears used by the artisanal fishing fleet. The position of vessels and gear types were obtained by visual surveys and related to spatial features of the marine park. A hotspot analysis was conducted to identify heavily utilized patches for each fishing gear and time period. The contribution of individual vessels to each significant cluster was assessed to better understand fishers' choices. Different fisheries responded differently to the implementation of protection measures, with preferred habitats of target species driving much of the fishers' choices. Within each fishery, individual fishers showed distinct strategies with some operating in a broader area whereas others kept preferred territories. Our findings are based on reliable methods that can easily be applied in coastal multipurpose MPAs to monitor and assess fisheries and fishers responses to different management rules and protection levels. This paper is the first in-depth empirical study where fishers' choices from artisanal fisheries were analysed before, during and after the implementation of a MPA, thereby allowing a clearer understanding of the dynamics of local fisheries and providing significant lessons for marine conservation and management of coastal systems

    Longer follow-up confirms recurrence-free survival benefit of adjuvant pembrolizumab in high-risk stage III melanoma: Updated results from the EORTC 1325-MG/KEYNOTE-054 trial

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    PURPOSE: We conducted the phase III double-blind European Organisation for Research and Treatment of Cancer (EORTC) 1325/KEYNOTE-054 trial to evaluate pembrolizumab versus placebo in patients with resected high-risk stage III melanoma. On the basis of 351 recurrence-free survival (RFS) events at a 1.25-year median follow-up, pembrolizumab prolonged RFS (hazard ratio [HR], 0.57; P \u3c .0001) compared with placebo. This led to the approval of pembrolizumab adjuvant treatment by the European Medicines Agency and US Food and Drug Administration. Here, we report an updated RFS analysis at the 3.05-year median follow-up. PATIENTS AND METHODS: A total of 1,019 patients with complete lymph node dissection of American Joint Committee on Cancer Staging Manual (seventh edition; AJCC-7), stage IIIA (at least one lymph node metastasis \u3e 1 mm), IIIB, or IIIC (without in-transit metastasis) cutaneous melanoma were randomly assigned to receive pembrolizumab at a flat dose of 200 mg (n = 514) or placebo (n = 505) every 3 weeks for 1 year or until disease recurrence or unacceptable toxicity. The two coprimary end points were RFS in the overall population and in those with programmed death-ligand 1 (PD-L1)-positive tumors. RESULTS: Pembrolizumab (190 RFS events) compared with placebo (283 RFS events) resulted in prolonged RFS in the overall population (3-year RFS rate, 63.7% v 44.1% for pembrolizumab v placebo, respectively; HR, 0.56; 95% CI, 0.47 to 0.68) and in the PD-L1-positive tumor subgroup (HR, 0.57; 99% CI, 0.43 to 0.74). The impact of pembrolizumab on RFS was similar in subgroups, in particular according to AJCC-7 and AJCC-8 staging, and BRAF mutation status (HR, 0.51 [99% CI, 0.36 to 0.73] v 0.66 [99% CI, 0.46 to 0.95] for V600E/Kv wild type). CONCLUSION: In resected high-risk stage III melanoma, pembrolizumab adjuvant therapy provided a sustained and clinically meaningful improvement in RFS at 3-year median follow-up. This improvement was consistent across subgroups

    Segmentation and kinematics of the North America-Caribbean plate boundary offshore Hispaniola

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    We explored the submarine portions of the Enriquillo–Plantain Garden Fault zone (EPGFZ) and the Septentrional–Oriente Fault zone (SOFZ) along the Northern Caribbean plate boundary using high-resolution multibeam echo-sounding and shallow seismic reflection. The bathymetric data shed light on poorly documented or previously unknown submarine fault zones running over 200 km between Haiti and Jamaica (EPGFZ) and 300 km between the Dominican Republic and Cuba (SOFZ). The primary plate-boundary structures are a series of strike-slip fault segments associated with pressure ridges, restraining bends, step overs and dogleg offsets indicating very active tectonics. Several distinct segments 50–100 km long cut across pre-existing structures inherited from former tectonic regimes or bypass recent morphologies formed under the current strike-slip regime. Along the most recent trace of the SOFZ, we measured a strike-slip offset of 16.5 km, which indicates steady activity for the past ~1.8 Ma if its current GPS-derived motion of 9.8 ± 2 mm a−1 has remained stable during the entire Quaternary.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu
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