262 research outputs found

    Con Respeto: A Conceptual Model for Building Healthy Community-University Partnerships Alongside Mexican Migrant Families

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    In this paper we grapple with the question of how healthy community and university partnerships can be formed in order to support migrant students’ access to higher education. Employing autoethnographic and narrative research, and drawing from our work within the context of the migrant family conference at California State University, Fullerton from 2011 to 2013, we outline a conceptual model for building healthy partnerships. The first section of this paper offers a general overview of the literature on community-university engagement and collaboration as well as provides background information about the migrant farmworker community. The next section puts forward a new conceptualization of community-university partnerships encompassing the dimensions of trust, validation, reciprocity, and interdependence. These dimensions are framed within the notion of respeto. Finally, the third section of this paper discusses challenges that surface in creating new collaborations as well as addresses practical implications in response to obstacles faced by migrant families. Ultimately, the problems, questions, and proposed frameworks are designed to open a dialogue on the language and lenses we use to characterize the quality of partnerships we seed with historically underserved communities

    Revealing patterns of local species richness along environmental gradients with a novel network tool

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    How species richness relates to environmental gradients at large extents is commonly investigated aggregating local site data to coarser grains. However, such relationships often change with the grain of analysis, potentially hiding the local signal. Here we show that a novel network technique, the “method of reflections”, could unveil the relationships between species richness and climate without such drawbacks. We introduced a new index related to potential species richness, which revealed large scale patterns by including at the local community level information about species distribution throughout the dataset (i.e., the network). The method effectively removed noise, identifying how far site richness was from potential. When applying it to study woody species richness patterns in Spain, we observed that annual precipitation and mean annual temperature explained large parts of the variance of the newly defined species richness, highlighting that, at the local scale, communities in drier and warmer areas were potentially the species richest. Our method went far beyond what geographical upscaling of the data could unfold, and the insights obtained strongly suggested that it is a powerful instrument to detect key factors underlying species richness patterns, and that it could have numerous applications in ecology and other fields

    Efectos del clima y la estructura del rodal sobre procesos de mortalidad en los bosques ibéricos.

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    Herrero A & Zavala MA, editores (2015) Los Bosques y la Biodiversidad frente al Cambio Climático: Impactos, Vulnerabilidad y Adaptación en España. Ministerio de Agricultura, Alimentación y Medio Ambiente, Madrid.Peer Reviewe

    Seed removal in two coexisting oak species: ecological consequences of seed size, plant cover and seed-drop timing

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    11 pages, 4 tables, 3 figures, 81 references.Seed predation and dispersal can critically influence plant community structure and dynamics. Inter-specific differences arising at these early stages play a crucial role on tree recruitment patterns, which in turn could influence forest dynamics and species segregation in heterogeneous environments such as Mediterranean forests. We investigated removal rates from acorns set onto the ground in two coexisting Mediterranean oak species Quercus canariensis and Q. suber in southern Spain. We developed maximum likelihood estimators to investigate the main factors controlling probabilities of seed removal and to describe species-specific functional responses. To account for inter-specific differences in seed-drop timing, two experiments were established: a simultaneous exposure of acorns of the two species (synchronous experiments) and a seed exposure following their natural seed-drop phenology (diachronic experiments). A total of 1536 acorns were experimentally distributed along a wide and natural gradient of plant cover, and removal was periodically monitored for three months at two consecutive years (with contrasting differences in seed production and thus seed availability on the ground). The probability of seed removal increased with plant cover (leaf area index, LAI) for the two oak species. Inter-specific differences in acorn removal were higher in open areas and disappeared in closed microhabitats, especially during a non-mast year. Despite later seed-drop, Q. suber acorns were removed faster and at a higher proportion than those of Q. canariensis. The higher probability of seed removal for this species could be attributed to its larger seed size compared to Q. canariensis, as inter-specific differences were less pronounced when similar sized acorns were exposed. Inter-specific differences in seed removal, arising from seed size variability and microsite heterogeneity, could be of paramount importance in oak species niche separation, driving stand dynamics and composition along environmental gradients.This study was supported by FPU and FPI-MEC grants to IMPR and IRU, and by the Spanish MEC projects Heteromed (REN2002-4041- C02-02) and Dinamed (CGL2005-5830-C03-01). This research is part of the Globimed (www.globimed.net) network on forest ecology.Peer reviewe

    Diode area melting single-layer parametric analysis of 316L stainless steel powder

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    Diode area melting (DAM) is a novel additive manufacturing process that utilises customised architectural arrays of low power laser diode emitters for high speed parallel processing of metallic powdered feedstock. The laser diodes operate at shorter laser wavelengths (808 nm) than conventional SLM fibre lasers (1064 nm) theoretically enabling more efficient energy absorption for specific materials. This investigation presents a parametric analysis of the DAM process, identifying the effect of powder characteristics, laser beam profile, laser power and scan speed on the porosity of a single-layer sample. Also presented is the effect of process energy density on melt pool depth (irradiated thermal energy penetration capable of achieving melting) on 316L stainless steel powder. An analysis of the density and the melt depth fraction of single layers is presented in order to identify the conditions that lead to the fabrication of fully dense DAM parts. Energy densities in excess of 86 J/mm3 were theorised as sufficient to enable processing of fully dense layers

    Dark Matter implications of the Fermi-LAT measurement of anisotropies in the diffuse gamma-ray background: status report

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    For the first time, the Fermi-LAT measured the angular power spectrum (APS) of anisotropies in the diffuse gamma-ray background. The data is found to be broadly compatible with a model with contributions from the point sources in the 1-year catalog, the galactic diffuse background, and the extragalactic isotropic emission; however deviations are present at both large and small angular scales. In this study, we complement the model with a contribution from Dark Matter (DM) whose distribution is modeled exploiting the results of the most recent N-body simulations, considering the contribution of extragalactic halos and subhalos (from Millennium-II) and of galactic substructures (from Aquarius). With the use of the Fermi Science Tools, these simulations serve as templates to produce mock gamma-ray count maps for DM gamma-ray emission, both in the case of an annihilating and a decaying DM candidate. The APS will then be computed and compared with the Fermi-LAT results to derive constraints on the DM particle physics properties. The possible systematic due to an imperfect model of the galactic foreground is also studied and taken into account properly. The present paper reports on the status of the project.Comment: Proceeding for the RICAP2011 conferenc

    Revealing patterns of local species richness along environmental gradients with a novel network tool

    Get PDF
    How species richness relates to environmental gradients at large extents is commonly investigatedaggregating local site data to coarser grains. However, such relationships often change with the grainof analysis, potentially hiding the local signal. Here we show that a novel network technique, the"method of reflections", could unveil the relationships between species richness and climate withoutsuch drawbacks. We introduced a new index related to potential species richness, which revealedlarge scale patterns by including at the local community level information about species distributionthroughout the dataset (i.e., the network). The method effectively removed noise, identifying howfar site richness was from potential. When applying it to study woody species richness patterns inSpain, we observed that annual precipitation and mean annual temperature explained large parts ofthe variance of the newly defined species richness, highlighting that, at the local scale, communitiesin drier and warmer areas were potentially the species richest. Our method went far beyond whatgeographical upscaling of the data could unfold, and the insights obtained strongly suggested that itis a powerful instrument to detect key factors underlying species richness patterns, and that it couldhave numerous applications in ecology and other fields.Comunidad de MadridMinisterio de Economía y Competitivida

    Evaluating tree-to-tree competition during stand development in a relict Scots pine forest: how much does climate matter?

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    Key message: Competitive interactions change over time and their influence on tree growth is intensified during drought events in marginal Scots pine populations. Abstract: Competition is a key factor driving forest dynamics and stand structure during the course of stand development. Although the role neighbourhood competition on stand dynamics has received increasing attention, the response of competition to environmental fluctuations and stand development remains poorly explored. We evaluated changes in competition during stand development in a dry-edge Scots pine relict population located in Central Spain. Typically, tree-to-tree interactions have been investigated through static competition measurements, which usually lack the temporal variation associated to natural forest development and environmental conditions. Here, we assessed how individual and neighbourhood components of competition evolved along a 35-year period, and we related competition dynamics to population structure and drought levels. On six plots, 508 trees were mapped and diameters at breast height (DBH) were measured. Two increment cores were taken from target trees to derive basal area increment (BAI), and neighbourhood was reconstructed back to 1980. Results provide insights into inter-annual variability in competition effects and their role on tree radial growth depending on climatic conditions. From the year 2005 onwards, both individual and neighbourhood components of competition showed a decoupled pattern over time. This effect was particularly pronounced during the extreme drought in 2012, in which the individual component decreased, whereas the neighbourhood component increased. In addition, climatic variability modulated the competition effects during stand development. This approach of evaluating competition dynamics proves to be promising for studying forest stand development and the influence of climate impacts on tree populations subjected to xeric conditions

    Land use change in a Mediterranean metropolitan region and its periphery: Assessment of conservation policies through CORINE land cover data and Markov models

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    Sustainable territorial management requires reliable assessment of the impact of conservation policies on landscape structure and dynamics. Euro-Mediterranean regions present a remarkable biodiversity which is linked in part to traditional land use practices and which is currently threatened by global change. The effectiveness of one-decade conservation policies against land use changes was examined in Central Spain (Madrid Autonomous Community). A Markov model of landscape dynamics was parameterized with CORINE Land Cover information and transition matrices were obtained. The methods were applied in both protected and unprotected areas to examine whether the intensity and direction of key land use changes —urbanisation, agricultural intensification and land abandonment— differed significantly depending on the protection status of those areas. Protected areas experienced slower rates of agricultural intensification processes and faster rates of land abandonment, with respect to those which occurred in unprotected areas. It illustrates how simple mathematical tools and models —parameterized with available data— can provide to managers and policy makers useful indicators for conservation policy assessment and identification of land use transitions
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