Caracterização palinológica da flora melitófila da reserva extrativista do Delta do Parnaíba.

Este trabalho é uma contribuição para o conhecimento palinológico da flora melitófila da RESEX do Delta do Parnaíba, onde ocorrem abelhas nativas sem ferrão produtoras de mel

Variations in Amazonian forest canopy structure and light environments across environmental and disturbance gradients.

A critical problem in tropical forest ecology is understanding how vegetation structure and function vary over environmental gradients. The degree to which forest structure changes across the Amazon basin and the role of environmental variability in shaping forest structure and dynamics are poorly characterised, despite the importance of these forests for regional and global climate. To address these challenges, we connected 10 years of investigations to amass a large database of ground-based profiling canopy lidar (PCL) data from 297 Amazon forest plots across large-scale environmental and disturbance gradients. Mean annual precipitation varied from 1,963 to 3,159 mm, number of dry season months from 0 to 5, and plot soil types covered about half of the variation in phosphorus, exchangeable cation, and soil physical property values observed in Amazonia. We quantified detailed metrics of vertical and horizontal structure and canopy light environments. Forest structure varied considerably across plots; maximum canopy height ranged from 6.1 to 35.7 m, gap fraction from 0.00 to 0.36, LAI from 0.5 to 7.3, rugosity from 1.5 to 7.5 m, and the relative height of 50% light transmission from 0.3 to 0.8. Disturbed sites exhibited almost twice the level of variation (SD) to non-disturbed sites for many metrics. Vertical leaf area density (LAD) profiles also showed high between plot variability, especially at low and high relative canopy heights. Plots with similar LAD profiles sometimes exhibited different distributions of ?canopy photic environment layers??where canopy leaf area is separated into photic environment layers by depth from canopy surface. This demonstrates that LAD profiles alone are insufficient for characterising canopy environments, essential to light-driven regeneration and carbon cycle processes. In addition, we evaluated relationships between lidar metrics and environmental variables extracted from geospatial layers. Our dataset allows a unique and detailed multi-site analysis of canopy structure and environments across the Amazon, including regions with little or no lidar sampling. Examining how structural attributes alter across environmental gradients is critical to understanding how current and future climate influences Amazonian forest structure, function, and dynamics.Paper 499657

Comparative analysis between condom use clusters and risk behaviours among portuguese university students

The research on condom use has been focused on high-risk individuals, paying less attention to those who have moderate risk or safe sexual conducts. In order to design accurate interventions, potential differences among the condom use behavior groups must be considered. The goal was to assess possible differences in individuals presenting different types of risk behavior. 140 heterosexual university students answered a self-reported questionnaire about their sexual history, condom use habits, sexual self-esteem, sexual satisfaction, sexual control, attitudes towards condoms, self-efficacy to condom use, and emotions and feelings during sexual intercourse. A cluster analysis was conducted using the results about condom use and risk behaviors. Three groups with different risk levels emerged, presenting differences over sexual self-efficacy, attitudes towards condoms, socio-demographic variables, and sexual history. The results suggest the condom use inconsistency is highly associated with other risk behaviors but the contrary does not necessarily happens. Condom use consistent users also presented risk behaviors as smoking and drinking. The group differences suggest the risks were more affected by the combination of lack of skills with a negative attitude toward condoms than by contextual or personal variables. These differences sustain the need of an intervention adjusted to the individual's risk levels, since they differ on skills and beliefs that may hinder or promote the adoption of health behaviors.Foundation for Science and Technology/Fundacao para a Ciencia e Tecnologia (Portugal)info:eu-repo/semantics/publishedVersio

Prenatal Vitamin D Supplementation and Child Respiratory Health: A Randomised Controlled Trial

PMCID: PMC3691177This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

A social and ecological assessment of tropical land uses at multiple scales: the Sustainable amazon network

Science has a critical role to play in guiding more sustainable development trajectories. Here, we present the Sustainable Amazon Network (Rede Amazônia Sustentável, RAS): a multidisciplinary research initiative involving more than 30 partner organizations working to assess both social and ecological dimensions of land-use sustainability in eastern Brazilian Amazonia. The research approach adopted by RAS offers three advantages for addressing land-use sustainability problems: (i) the collection of synchronized and co-located ecological and socioeconomic data across broad gradients of past and present human use; (ii) a nested sampling design to aid comparison of ecological and socioeconomic conditions associated with different land uses across local, landscape and regional scales; and (iii) a strong engagement with a wide variety of actors and non-research institutions. Here, we elaborate on these key features, and identify the ways in which RAS can help in highlighting those problems in most urgent need of attention, and in guiding improvements in land-use sustainability in Amazonia and elsewhere in the tropics. We also discuss some of the practical lessons, limitations and realities faced during the development of the RAS initiative so far

Effective Soft-Core Potentials and Mesoscopic Simulations of Binary Polymer Mixtures

Mesoscopic molecular dynamics simulations are used to determine the large scale structure of several binary polymer mixtures of various chemical architecture, concentration, and thermodynamic conditions. By implementing an analytical formalism, which is based on the solution to the Ornstein-Zernike equation, each polymer chain is mapped onto the level of a single soft colloid. From the appropriate closure relation, the effective, soft-core potential between coarse-grained units is obtained and used as input to our mesoscale simulations. The potential derived in this manner is analytical and explicitly parameter dependent, making it general and transferable to numerous systems of interest. From computer simulations performed under various thermodynamic conditions the structure of the polymer mixture, through pair correlation functions, is determined over the entire miscible region of the phase diagram. In the athermal regime mesoscale simulations exhibit quantitative agreement with united atom simulations. Furthermore, they also provide information at larger scales than can be attained by united atom simulations and in the thermal regime approaching the phase transition.Comment: 19 pages, 11 figures, 3 table