975 resultados para Environment and Natural Resources


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Tropical forests are experiencing an increase in the proportion of secondary forests as a result of the balance between the widespread harvesting of old-growth forests and the regeneration in abandoned areas. The impacts of such a process on biodiversity are poorly known and intensely debated. Recent reviews and multi-taxa studies indicate that species replacement in wildlife assemblages is a consistent pattern, sometimes stronger than changes in diversity, with a replacement from habitat generalists to old-growth specialists being commonly observed during tropical forest regeneration. However, the ecological drivers of such compositional changes are rarely investigated, despite its importance in assessing the conservation value of secondary forests, and to support and guide management techniques for restoration. By sampling 28 sites in a continuous Atlantic forest area in Southeastern Brazil, we assessed how important aspects of habitat structure and food resources for wildlife change across successional stages, and point out hypotheses on the implications of these changes for wildlife recovery. Old-growth areas presented a more complex structure at ground level (deeper leaf litter, and higher woody debris volume) and higher fruit availability from an understorey palm, whereas vegetation connectivity, ground-dwelling arthropod biomass, and total fruit availability were higher in earlier successional stages. From these results we hypothetize that generalist species adapted to fast population growth in resource-rich environments should proliferate and dominate earlier successional stages, while species with higher competitive ability in resource-limited environments, or those that depend on resources such as palm fruits, on higher complexity at the ground level, or on open space for flying, should dominate older-growth forests. Since the identification of the drivers of wildlife recovery is crucial for restoration strategies, it is important that future work test and further develop the proposed hypotheses. We also found structural and functional differences between old-growth forests and secondary forests with more than 80 years of regeneration, suggesting that restoration strategies may be crucial to recover structural and functional aspects expected to be important for wildlife in much altered ecosystems, such as the Brazilian Atlantic forest. (C) 2012 Elsevier B.V. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The objective of this work was to evaluate the toxicity of synthetic and natural compounds on Tetranychus urticae and the predator Phytoseiulus macropilis. Mortality and growth rates of T. urticae and its predator were evaluated after applications of: abamectin, clofentezine, fenpropathrin, fenpyroximate, propargite, sulfur and spiromesifen, at their recommended concentrations; neem oils (Natuneem and Sempre Verde Killer Neem at 1%); and aqueous extracts at 10% of Dieffenbachia brasiliensis, Annona squamosa, Ruta graveolens, Agave angustifolia, Melia azedarach, Sonchus oleraceus, Mentha spicata x M. suaveolens, Allium cepa, Laurus nobilis, and Eucalyptus saligna. The acute toxicity and the influence of the compounds on the instantaneous growth rate of the mites were carried out in laboratory. Extracts of A. cepa, A. angustifolia, neem oil-based products, spiromesifen, propargite, fenpyroximate, abamectin and fenpropathrin caused mortality higher than 83% on T. urticae. Extract of A. angustifolia, Natuneem and clofentezine did not cause significant mortality rates on P. macropilis. Agave angustifolia and Natuneem did not affect significantly the growth rate of this predator. Propargite, fenpyroximate, abamectin, fenpropathrin, spiromesifen and extract of L. nobilis severely affected P. macropilis population.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Environmental biomonitoring has demonstrated that organisms such as crustaceans, fish and mushrooms are useful to evaluate and monitor both ecosystem contamination and quality. Particularly, some mushroom species have a high capacity to retain radionuclides and some toxic elements from the soil and the air. The potential of mushrooms to accumulate radionuclides in their fruit-bodies has been well documented. However, there are no studies that determine natural and artificial radionuclide composition in edible mushrooms, in Brazil. Artificial (Cs-137) and natural radioactivity (K-40. Ra-226. Ra-228) were determined in 17 mushroom samples from 3 commercialized edible mushroom species. The edible mushrooms collected were Agaricus sp., Pleurotus sp. and Lentinula sp. species. The activity measurements were carried out by gamma spectrometry. The levels of Cs-137 varied from 1.45 +/- 0.04 to 10.6 +/- 0.3 Bq kg(-1), K-40 levels varied from 461 +/- 2 to 1535 +/- 10 Bq kg(-1), Ra-226 levels varied from 14 +/- 3 to 66 +/- 12 Bq kg(-1) and Ra-228 levels varied from 6.2 +/- 0.2 to 54.2 +/- 1.7 Bq kg(-1). Cs-137 levels in Brazilian mushrooms are in accordance with the radioactive fallout in the Southern Hemisphere. The artificial and natural activities determined in this study were found to be below the maximum permissible levels as established by national legislation. Thus, these mushroom species can be normally consumed by the population without any apparent risks to human health.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Most biological systems are formed by component parts that are to some degree interrelated. Groups of parts that are more associated among themselves and are relatively autonomous from others are called modules. One of the consequences of modularity is that biological systems usually present an unequal distribution of the genetic variation among traits. Estimating the covariance matrix that describes these systems is a difficult problem due to a number of factors such as poor sample sizes and measurement errors. We show that this problem will be exacerbated whenever matrix inversion is required, as in directional selection reconstruction analysis. We explore the consequences of varying degrees of modularity and signal-to-noise ratio on selection reconstruction. We then present and test the efficiency of available methods for controlling noise in matrix estimates. In our simulations, controlling matrices for noise vastly improves the reconstruction of selection gradients. We also perform an analysis of selection gradients reconstruction over a New World Monkeys skull database to illustrate the impact of noise on such analyses. Noise-controlled estimates render far more plausible interpretations that are in full agreement with previous results.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Anadia pariaensis Rivas, La Marca, and Oliveros, 1999, and Anadia steyeri Nieden, 1914, are two particularly rare and poorly known lizards described from single specimens. In the case of A. pariaensis, it remains known from the holotype, whereas A. steyeri is known from three additional specimens reported in the literature after the original description of the species. A single new specimen of A. pariaensis and five of A. steyeri, including the first adult males recorded for both species, make possible a more representative description of both species, including descriptions of the hemipenes. Despite both species presenting some similar morphological characteristics, the examination of the hemipenial morphology revealed very different organs. The hemipenis of A. steyeri presents some characteristics that resemble the organs of two species from the Santa Marta Mountain Range in the "bitaeniata-group" (Anadia pulchella and Anadia altaserrania). On the other hand, the hemipenes of A. pariaensis are unique morphologically and cannot be associated with the hemipenes known from other species in the genus. We describe variation within both species, and we comment on possible sexual dimorphism (number and arrangement of the femoral pores), natural history, and the known geographic distribution of the species. We also comment on Anadia bumanguesa Rueda-Almonacid and Caicedo 2004 based on a new specimen, the second known. This species may be a synonym of A. steyeri.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The use of sewage sludge is a highly promising practice for the development of sustainable agricultural systems. The objective of this study was to evaluate doses of sewage sludge composted with and without Rhizobium inoculation in leaf N content, nodule number, nodule dry weight and plant during flowering. The experiment was conducted in the greenhouse of the Department of Soil Science and Natural Resources College of Agricultural Sciences of Botucatu, using as substrate used in vessels of 30 liters a Red Yelow Latosol sandy texture with experimental design adopted was randomized blocks constituted for 10 treatments and five doses of composted sewage sludge (0, 10, 20, 30, 40 t ha(-1)) with or without inoculation Bradyrhizobium japonic with three replications. There was an increase in the number and dry weight of nodules and shoot dry mass of soybeans due to the increase of the dose of sludge up to a dose of 20 t ha(-1) and after this dose there was a decrease of these parameters. At a dose of 10 t ha(-1) sludge compost inoculated seeds showed higher for foliar concentrations of N and number of nodules compared with uninoculated seeds. At a dose of 30 t ha(-1) inoculated seeds were higher compared to uninoculated in all parameters.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Introduction: This study aimed to isolate and identify Candida spp. from the environment, health practitioners, and patients with the presumptive diagnosis of candidiasis in the Pediatric Unit at the Universitary Hospital of the Jundiai Medical College, to verify the production of enzymes regarded as virulence factors, and to determine how susceptible the isolated samples from patients with candidiasis are to antifungal agents. Methods: Between March and November of 2008 a total of 283 samples were taken randomly from the environment and from the hands of health staff, and samples of all the suspected cases of Candida spp. hospital-acquired infection were collected and selected by the Infection Control Committee. The material was processed and the yeast genus Candida was isolated and identified by physiological, microscopic, and macroscopic attributes. Results: The incidence of Candida spp. in the environment and employees was 19.2%. The most frequent species were C. parapsilosis and C. tropicalis among the workers, C. guilliermondii and C. tropicalis in the air, C. lusitanae on the contact surfaces, and C. tropicalis and C. guilliermondii in the climate control equipment. The college hospital had 320 admissions, of which 13 (4%) presented Candida spp. infections; three of them died, two being victims of a C. tropicalis infection and the remaining one of C. albicans. All the Candida spp. in the isolates evidenced sensitivity to amphotericin B, nystatin, and fluconazole. Conclusions: The increase in the rate of hospital-acquired infections caused by Candida spp. indicates the need to take larger measures regarding recurrent control of the environment.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

INTRODUCTION: This study aimed to isolate and identify Candida spp. from the environment, health practitioners, and patients with the presumptive diagnosis of candidiasis in the Pediatric Unit at the Universitary Hospital of the Jundiaí Medical College, to verify the production of enzymes regarded as virulence factors, and to determine how susceptible the isolated samples from patients with candidiasis are to antifungal agents. METHODS: Between March and November of 2008 a total of 283 samples were taken randomly from the environment and from the hands of health staff, and samples of all the suspected cases of Candida spp. hospital-acquired infection were collected and selected by the Infection Control Committee. The material was processed and the yeast genus Candida was isolated and identified by physiological, microscopic, and macroscopic attributes. RESULTS: The incidence of Candida spp. in the environment and employees was 19.2%. The most frequent species were C. parapsilosis and C. tropicalis among the workers, C. guilliermondii and C. tropicalis in the air, C. lusitanae on the contact surfaces, and C. tropicalis and C. guilliermondii in the climate control equipment. The college hospital had 320 admissions, of which 13 (4%) presented Candida spp. infections; three of them died, two being victims of a C. tropicalis infection and the remaining one of C. albicans. All the Candida spp. in the isolates evidenced sensitivity to amphotericin B, nystatin, and fluconazole. CONCLUSIONS: The increase in the rate of hospital-acquired infections caused by Candida spp. indicates the need to take larger measures regarding recurrent control of the environment.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Yolk color and egg white (albumen) cleanliness and viscosity are important parameters by which consumers judge the quality of eggs. This study aimed to investigate changes in albumen viscosity during storage of eggs for up to 36 days from two different commercial laying hen strains (Carijo Barbada and Isa Brown) fed a diet containing annatto (1.5 and 2.0%) or a synthetic additive without synthetic colorants (control). Analyses of humidity, albumen height, pH, viscosity, foam formation, and stability were carried out on eggs. Carijo Barbada strain had smaller albumen, lower humidity and higher egg white viscosity than Isa Brown strain; however, with storage, viscosity lowered significantly on both strains. Initially, the addition of 2.0% of annatto or a synthetic additive increased viscosity in both strains, but with storage only the control maintained longer viscosity. Lower viscosity did not change foam density and stability.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The emergence and maintenance of maternal behavior are under the influence of environmental cues such as light and dark periods. This article discusses the characteristic neurobiology of the behavioral patterns of lactating rats. Specifically, the hormonal basis and neurocircuits that determine whether mother rats show typical sequential patterns of behavioral responses are discussed. During lactation, rats express a sequential pattern of behavioral parameters that may be determined by hormonal variations. Sensorial signals emitted by pups, as well as environmental cues, are suggested to serve as conditioned stimuli for these animals. Finally, the expression of maternal behavior is discussed under neuroeconomic and evolutionary perspectives.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Programa de doctorado: Ecología y Gestión de los Recursos Vivos Marinos

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This thesis provides efficient and robust algorithms for the computation of the intersection curve between a torus and a simple surface (e.g. a plane, a natural quadric or another torus), based on algebraic and numeric methods. The algebraic part includes the classification of the topological type of the intersection curve and the detection of degenerate situations like embedded conic sections and singularities. Moreover, reference points for each connected intersection curve component are determined. The required computations are realised efficiently by solving quartic polynomials at most and exactly by using exact arithmetic. The numeric part includes algorithms for the tracing of each intersection curve component, starting from the previously computed reference points. Using interval arithmetic, accidental incorrectness like jumping between branches or the skipping of parts are prevented. Furthermore, the environments of singularities are correctly treated. Our algorithms are complete in the sense that any kind of input can be handled including degenerate and singular configurations. They are verified, since the results are topologically correct and approximate the real intersection curve up to any arbitrary given error bound. The algorithms are robust, since no human intervention is required and they are efficient in the way that the treatment of algebraic equations of high degree is avoided.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Findings on socioeconomic health differentials in youth remain fragmented with the role of cumulative and interaction effects of different forms of health resources not well understood.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Humankind today is challenged by numerous threats brought about by the speed and scope of global change dynamics. A concerted and informed approach to solutions is needed to face the severity and magnitude of current development problems. Generating shared knowledge is a key to addressing global challenges. This requires developing the ability to cross multiple borders wherever radically different understandings of issues such as health and environmental sanitation, governance and conflict, livelihood options and globalisation, and natural resources and development exist. Global Change and Sustainable Development presents 36 peer-reviewed articles written by interdisciplinary teams of authors who reflected on results of development-oriented research conducted from 2001 to 2008. Scientific activities were – and continue to be – carried out in partnerships involving people and institutions in the global North, South and East, guided by principles of sustainability. The articles seek to inform solutions for mitigating, or adapting to, the negative impacts of global dynamics in the social, political, ecological, institutional and economic spheres.