945 resultados para human influence
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Human activities have been driven land cover, provoking acceleration of the erosive process and alteration on the soil characteristics. To explore the effects of human disturbance, we investigated the influences of natural and anthropogenic features on soil quality and soil erosion indicators (EI) within a Brazilian rural watershed located in Bauru Municipality, State of So Paulo. A pre-established set of soil EI was used to evaluate the influence of anthropogenic land cover categories on the presence and severity of erosion, related with spatial variations of soil attributes. On-site visits were carried out to measure the occurrence and the intensity of eleven separate EI values and to collect undisturbed topsoil samples for subsequent analyses. We registered 17 occurrences of EIs, distributed in ten locals. Occurrence and intensity of EIs were related to degree of sheet erosion. The EI qualities were more strongly associated with land cover management practices than to local topographic features. The occurrence of EIs and characteristics of soil and soil organic matter (SOM) were not significantly self-correlated. Although land cover class seems to influence soil properties and SOM attributes, we observed that the granulometric composition of the soils also contributes to the structural characteristics of the soil and consequently to the dynamic loss and gain of soil carbon. Sites covered with natural remnant vegetation (NRV) store 96.5 Mg ha(-1) of C and grassy and tilled soils stored more C than NRV, 100.1 and 142.4 Mg ha(-1), respectively. Due to the influence of soil texture over the soil C dynamic, we observe that in Bauru, pastured areas have high potential for sequestration of C if factors such as fire and/or erosion were avoided or effectively controlled. Results from this study show that human disturbance substantially affects soil properties within of southeastern region of Brazil.
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The goal of this study is to present and test a conceptual framework that describes the technical aspects (TA), human/organizational aspects (HOA) of the adoption of green product development (GPD) practices and the effect of these practices on firms'environmental (EP), operational (OP) and market performance (MP). To this end, after reviewing the literature on these themes, a conceptual framework with 5 hypotheses is proposed. These hypotheses were tested on 62 Brazilian companies through structural equation modeling using SmartPLS 2.0M3. The main results of this study are as follows: (a) in general, the proposed framework obtained adequate goodness of fit statistics (GoF); (b) technological factors are shown to have an influence on the adoption of GPD practices, and those practices are related to company EP, OP and MP, thus confirming 4 hypotheses of the study; and (c) one of the study's hypotheses is not validated, indicating that the relationship of human/organizational aspects to GPD must be further analyzed. This work extends the literature because: (a) the conceptual framework tested in this study establishes several concepts that have been only partially tested in the previous literature; (b) this work presents evidence about Brazil, where the themes addressed herein have not been yet been thoroughly investigated; and (c) the non-validation of the hypothesis regarding the relationship between human/ organizational aspects with respect to the adoption of product-related environmental practices requires attention. (C) 2014 Elsevier Ltd. All rights reserved.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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The aim of this study was to assess the influence of the quantity of coloring agent on the bleaching efficiency of gels containing 35% H2O2. Sixty human third molars were sectioned mesiodistally, darkened in a coffee solution and sectioned in the occlusal-cervical direction, resulting in mesial (not bleached) and distal halves (bleached). They were distributed into three groups: Whiteness HP, Total Bleach, and Whiteform Perox Red Gel; and subdivided into four sub-groups: no coloring agent, manufacturer's standard, double the standard, and triple the standard. The gels were activated with light-ermitting diode/laser appliances. The images were analyzed with the Adobe Photoshop program (deltaEL*a*b*). The variation was submitted to the ANOVA test (two factors: type of gel and quantity of coloring agent) and Tukey test. Differences were observed for the quantity of coloring agent. The mean (+/-SD) was determined for each quantity of coloring used: no coloring agent -6.85 (+/-2.26)a, manufacturer's standard -794 (+/-2.55)ab, double the standard -8.65 (+/-2.47)b, triple the standard -9.05 (+/-2.72)b. In conclusion, the standard quantity of coloring agent did not provide significantly more intense bleaching than when it was completely absent. The use of double and triple the amount provided greater bleaching than that observed for the gel without coloring agent. No significant differences were observed between the tested gels.
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The aim of this study was to investigate the effects of Er:YAG and Nd:YAG lasers on the shear bond strength of composite resin to dentin. The coronal portion of 56 human molars was divided into three parts, and the dentin thickness was standardized at 2 mm. A 3-mm hole was marked in the center of each tooth with sealing tape paper. The specimens (n = 14) were then divided into four groups: (1) acid etching + Single Bond (SB) (control), (2) acid etching + SB + Nd:YAG laser irradiation (before adhesive curing), (3) thermal etching with the Er:YAG laser + SB, and (4) thermal etching with the Er:YAG laser + SB + Nd:YAG laser irradiation (before adhesive curing). A composite resin cylinder was built into the delimited area for conducting the shear bond strength test on the universal testing machine. The means ± standard deviations were: group 1, 17.05 ± 4.15 MPa; group 2, 16.90 ± 3.36 MPa; group 3, 12.12 ± 3.85 MPa; and group 4, 12.92 ± 2.73 MPa. Groups 1 and 2 presented significantly higher values than groups 3 and 4. It was concluded that conventional etching with 37% phosphoric acid yielded significantly higher bond strength values compared to thermal etching with the Er:YAG laser. The Nd:YAG laser did not significantly influence the bond strength.
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Population genetics theory predicts loss in genetic variability because of drift and inbreeding in isolated plant populations; however, it has been argued that long-distance pollination and seed dispersal may be able to maintain gene flow, even in highly fragmented landscapes. We tested how historical effective population size, historical migration and contemporary landscape structure, such as forest cover, patch isolation and matrix resistance, affect genetic variability and differentiation of seedlings in a tropical palm (Euterpe edulis) in a human-modified rainforest. We sampled 16 sites within five landscapes in the Brazilian Atlantic forest and assessed genetic variability and differentiation using eight microsatellite loci. Using a model selection approach, none of the covariates explained the variation observed in inbreeding coefficients among populations. The variation in genetic diversity among sites was best explained by historical effective population size. Allelic richness was best explained by historical effective population size and matrix resistance, whereas genetic differentiation was explained by matrix resistance. Coalescence analysis revealed high historical migration between sites within landscapes and constant historical population sizes, showing that the genetic differentiation is most likely due to recent changes caused by habitat loss and fragmentation. Overall, recent landscape changes have a greater influence on among-population genetic variation than historical gene flow process. As immediate restoration actions in landscapes with low forest amount, the development of more permeable matrices to allow the movement of pollinators and seed dispersers may be an effective strategy to maintain microevolutionary processes.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Objective: The objective of this study was to evaluate the effect of Er: YAG laser on the formation of CaF2, after the application of acidulated phosphate fluoride (APF), and its influence on the anti-cariogenic action in human dental enamel. Background Data: Er:YAG laser was designed to promote ablation of the enamel. However, the possibility of using this energy to increase the enamel's resistance to caries has hardly been explored, and neither has its interaction with the use of fluorides. Materials and Methods: One hundred and twenty blocks of enamel were allocated to four groups of 30 blocks each: (1) C, control group; (2) Er:YAG, laser; (3) APF; and (4) Er:YAG+APF. Of these, 80 blocks were submitted to pH cycling for 14 days. In the other 40 blocks, fluoride (CaF2) was measured before cycling. After pH cycling, surface microhardness (SMH), microhardness in cross-section (converted to mineral contents % vol. min.), and fluoride after cycling (40 blocks) were also determined. Results: SMH decreased in all groups. The control group showed the highest decrease, and Er:YAG+APF showed the lowest decrease (p < 0.05). Groups APF and Er:YAG showed the same results (p > 0.05). Mineral content at depths 10, 20, and 40 μm was lower in the control and Er:YAG groups, and higher in groups APF and Er:YAG+APF. CaF2 (μgF/cm2) deposited before pH cycling was higher in the APF group when compared to the Er:YAG+APF group. Control and Er:YAG groups showed the lowest values (p > 0.05). Conclusion: It was concluded that Er:YAG laser influenced the deposition of CaF2 on the enamel and showed a superficial anti-cariogenic action, but not in depth.
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Human leukocyte antigen-G (HLA-G) is a non-classical major histocompatibility complex class Ib molecule that acts as a specific immunosuppressor. Some studies have demonstrated that human papillomavirus (HPV) seems to be involved in lower or absent HLA-G expression, particularly in cervical cancer. In this study, we performed a cross-sectional study, systematically comparing the qualitative expression of the HLA-G5 isoform in invasive cervical carcinoma (ICC), stratifying patients according to the presence [ICC with metastasis (ICCW)] and absence [ICC without metastasis (ICCWT)] of metastasis, correlating these findings with interference of HPV and demographic and clinical variables. Seventy-nine patients with a diagnosis of ICC were stratified into two groups: ICCWT (n=52 patients) and ICCW (n=27). Two biopsies were collected from each patient (one from the tumor lesion and one from a lymph node). Immunohistochemistry analyses were performed for the HLA-G5 isoform, for HPV detection, and virus typing. HLA-G5 isoform molecules were detected in 25 cases (31.6%), 17 (32.7%) without metastasis and 8 (29.6%) with metastasis. HPV was detected in the cervical lesions of 74 patients (93.7%), but low expression of the HLA-G5 isoform was observed in all HPV-related cases. These findings are important; however, additional studies are necessary to identify the influence of HPV with HLA-G5 isoform expression on invasive cervical malignancies.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The influence of deposition parameters, namely polymer concentration and pH of the deposition solution, cleaning, and drying steps on the morphology and electrical characteristics of polyaniline and sulfonated polystyrene (PANI/PSS) nanostructured films deposited by the self-assembly technique is evaluated by UV-Vis spectroscopy, optical and atomic force microscopy, and electrical resistance measurements. It is found that stirring the cleaning solution during the cleaning step is crucial for obtaining homogenous films. Stirring of the cleaning solution also influences the amount of PANI adsorbed in the films. In this regard, the drying process seems to be less critical since PANI amount and film thickness are similar in films dried with N-2 flow or with an absorbent tissue. It is observed, however, that drying with N-2 flow results in rougher films. As an additional point, an assessment of the influence of the deposition method (manual versus mechanical) on the film characteristics was carried out. A significant difference on the amount of PANI and film thickness between films prepared by different human operators and by a homemade mechanical device was observed. The variability in film thickness and PANI adsorbed amount is smaller in films mechanically assembled. (c) 2007 Elsevier B.V. All rights reserved.