181 research outputs found

    Regional international migration distribution in Spain: which factors are behind?

    Get PDF
    International migration issues are at the forefront of the political debate in the European Union (EU). Some reasons justify the increasing relevance of this topic, being the unprecedented scale of international migration flows, especially in countries such as Spain, the most prominent. In fact, adequate responses to the necessity for controlling effectively large flows of irregular immigration, and also safeguarding the internal security, are insistently demanded and always placed in the center of the political debate. Thus, recent studies portraying immigration experiences in the EU have been prolific in the literature on international migration. Some of these were applied to Spain as a representative country of changes in international migration patterns. However, and although some contributions to the analysis of international migration in Spain have been made, an examination of the international migration distribution (IMD) is still a pending question that needs further analysis. Accordingly, the aim of this paper is to analyse some relevant aspects on IMD in Spain at regional level. After a descriptive analysis showing the importance that international migration plays in today’s Spanish demography and economy, the paper examines the IMD’s external shape and its intra-distribution mobility. Subsequently, an analysis of the factors that might be behind the IMD and its dynamics is carried out. The results will give information about the role played by factors such as geographical location, per capita income, industry mix, employment density and social networks in explaining this issue. Keywords: international migration; Spanish regions; distribution dynamics; highest density regions

    Are Local Filters Blind to Provenance? Ant Seed Predation Suppresses Exotic Plants More than Natives

    Get PDF
    The question of whether species’ origins influence invasion outcomes has been a point of substantial debate in invasion ecology. Theoretically, colonization outcomes can be predicted based on how species’ traits interact with community filters, a process presumably blind to species’ origins. Yet, exotic plant introductions commonly result in monospecific plant densities not commonly seen in native assemblages, suggesting that exotic species may respond to community filters differently than natives. Here, we tested whether exotic and native species differed in their responses to a local community filter by examining how ant seed predation affected recruitment of eighteen native and exotic plant species in central Argentina. Ant seed predation proved to be an important local filter that strongly suppressed plant recruitment, but ants suppressed exotic recruitment far more than natives (89% of exotic species vs. 22% of natives). Seed size predicted ant impacts on recruitment independent of origins, with ant preference for smaller seeds resulting in smaller seeded plant species being heavily suppressed. The disproportionate effects of provenance arose because exotics had generally smaller seeds than natives. Exotics also exhibited greater emergence and earlier peak emergence than natives in the absence of ants. However, when ants had access to seeds, these potential advantages of exotics were negated due to the filtering bias against exotics. The differences in traits we observed between exotics and natives suggest that higher-order introduction filters or regional processes preselected for certain exotic traits that then interacted with the local seed predation filter. Our results suggest that the interactions between local filters and species traits can predict invasion outcomes, but understanding the role of provenance will require quantifying filtering processes at multiple hierarchical scales and evaluating interactions between filters.Fil: Pearson, Dean. University of Montana; Estados Unidos. United States Department of Agriculture; Estados UnidosFil: Icasatti, Nadia Soledad. United States Department of Agriculture; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hierro, Jose Luis. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Bird, Benjamin B.. United States Department of Agriculture; Estados Unido

    Provincial international migration distribution in Spain: which factors are behind?

    Full text link
    International migration issues are at the forefront of the political debate in the European Union (EU). Some reasons justify the increasing relevance of this topic, being the unprecedented scale of international migration flows, especially in countries such as Spain, the most prominent. In fact, adequate responses to the necessity for controlling effectively large flows of irregular immigration, and also safeguarding the internal security, are insistently demanded and always placed in the center of the political debate. Thus, recent studies portraying immigration experiences in the EU have been prolific in the literature on international migration. Some of these were applied to Spain as a representative country of changes in international migration patterns. However, and although some contributions to the analysis of international migration in Spain have been made, an examination of the international migration distribution (IMD) is still a pending question that needs further analysis. Accordingly, the aim of this paper is to analyse some relevant aspects on IMD in Spain at regional level. After a descriptive analysis showing the importance that international migration plays in today's Spanish demography and economy, the paper examines the IMD's external shape and its intra-distribution mobility. Subsequently, an analysis of the factors that might be behind the IMD and its dynamics is carried out. The results will give information about the role played by factors such as geographical location, per capita income, industry mix, employment density and social networks in explaining this issue

    Cabeza de Hierro: un monte privado, ordenado y ejemplo de multifuncionalidad.

    Get PDF
    El monte “Cabeza de Hierro”, masa natural de pino silvestre, es un ejemplo de gestión forestal sostenible y de uso múltiple, y reúne ciertas particularidades que hacen muy interesante su caso. Monte privado, ha sido objeto de aprovechamientos madereros al menos desde su adquisición por sus actuales propietarios en 1840. Está ordenado desde 1957. La madera obtenida, de gran calidad, es transformada en su mayor parte en un aserradero cercano de los mismos propietarios. Generador de un considerable número de puestos de trabajo, ha tenido gran importancia en la economía local. Además de la producción de madera ha cumplido y cumple muy eficazmente numerosas funciones ecológicas y ambientales, entre las que podemos destacar la regulación del ciclo hidrológico y la protección frente a la erosión, la generación de un paisaje de gran belleza y el mantenimiento de la biodiversidad; en este sentido destacamos la presencia de una colonia nidificante de buitre negro de reconocida importancia mundial. Fue el primer caso de aplicación en España de los métodos de ordenación de tramo móvil y selvícola. En la tercera revisión de su ordenación, recientemente aprobada, se propone su gestión mediante entresaca regularizada, con cortas por bosquetes, con lo que se pretende mantener la actual estructura de masa irregular por cantones. A continuación se resumen las principales características del monte y las principales propuestas de gestión de su tercera revisión

    Soil compaction and vegetation cover in a Scots pine stand at the Mediterranean rangelands

    Get PDF
    Right development of ROOT SYSTEMS is essential to ensure seedling survival in the initial stages of natural regeneration processes. Soil compaction determines this development both because of its influence on soil Tª & moisture dynamics and for its direct effect on soil mechanical impedance to root growth. All this effects can be assessed as a whole through soil penetration resistance (Soil Strength) measurements. SOIL STRENGTH has been usually evaluated in forest research in connection with severe disturbances derived from heavy machinery works during forest operations. Nevertheless, undisturbed soils are also expected to show different levels of compaction for root development. Organic matter modifies soil structure and so on porosity, compaction and resultant soil resistance to penetration. Its concentration in surface layers is rather related to vegetation cover composition and density. So within forest stands, a relationship is expected to be found between VEGETATION COVER density and compaction measured as resistance to penetration (soil strength

    The fluctuating resource hypothesis explains invasibility, but not exotic advantage following disturbance

    Get PDF
    Invasibility is a key indicator of community susceptibility to changes in structure and function. The fluctuating resource hypothesis (FRH) postulates that invasibility is an emergent community property, a manifestation of multiple processes that cannot be reliably predicted by individual community attributes like diversity or productivity. Yet, research has emphasized the role of these individual attributes, with the expectation that diversity should deter invasibility and productivity enhance it. In an effort to explore how these and other factors may influence invasibility, we evaluated the relationship between invasibility and species richness, productivity, resource availability, and resilience in experiments crossing disturbance with exotic seed addition in 1-m2 plots replicated over large expanses of grasslands in Montana, USA and La Pampa, Argentina. Disturbance increased invasibility as predicted by FRH, but grasslands were more invasible in Montana than La Pampa whether disturbed or not, despite Montana´s higher species richness and lower productivity. Moreover, invasibility correlated positively with nitrogen availability and negatively with native plant cover. These patterns suggested that resource availability and the ability of the community to recover from disturbance (resilience) better predicted invasibility than either species richness or productivity, consistent with predictions from FRH. However, in ambient, unseeded plots in Montana, disturbance reduced native cover by >50% while increasing exotic cover >200%. This provenance bias could not be explained by FRH, which predicts that colonization processes act on species? traits independent of origins. The high invasibility of Montana grasslands following disturbance was associated with a strong shift from perennial to annual species, as predicted by succession theory. However, this shift was driven primarily by exotic annuals, which were more strongly represented than perennials in local exotic vs. native species pools. We attribute this provenance bias to extrinsic biogeographic factors such as disparate evolutionary histories and/or introduction filters selecting for traits that favor exotics following disturbance. Our results suggest that (1) invasibility is an emergent property best explained by a community´s efficiency in utilizing resources, as predicted by FRH but (2) understanding provenance biases in biological invasions requires moving beyond FRH to incorporate extrinsic biogeographic factors that may favor exotics in community assembly.Fil: Pearson, Dean. United State Forest Service; Estados Unidos. University of Montana; Estados UnidosFil: Ortega, Yvette K.. United State Forest Service; Estados UnidosFil: Villarreal, Diego. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Lekberg, Ylva. University of Montana; Estados UnidosFil: Cock, Marina Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Eren, Ozkan. Adnan Menderes Universitesi; TurquíaFil: Hierro, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentin

    Problemas del empirismo en la filosofia de la mente

    No full text
    Experience of mental states becomes central as soon as we attempt to construe a science of the mind. Mental states appear irreducible to physical states in as far as they are neither public nor computable. From an epistemological point of view mental states are peculiar in that we have no knowledge proper to them, we simply have them. From the point of view of our experience, there are reasons to reject the physicalist explanation as well as the intentionalist account and also to reject the reducibility of mental states to brain states. Two different forms of experience are relevant: direct experience of one's own mental states and indirect experience of other people's through their behavior and speech

    Older adults and sport and physical activity professionals in Spain

    Get PDF
    Presence of monitors in physical activities and sports practiced by adults older than 64 years of age in Spain is analyzed in this research. The objective of this study is to determine the existence of monitors in relation to the sociodemographic features of older adults, the size of municipalities, the activities practiced, and the organizations where they are performed. The methodology used included a cross-sectional survey applied to a sample of older adults in Spain. The most relevant conclusions are that the presence of monitors in physical activities and sports practiced by older adults is dominant (63.8%), hence, their importance, and that the presence of monitors is higher for women (81.3%) than for men (37.5%). In addition, it is concluded that the bigger the municipality the higher the tendency to have more instructors. Regarding the type of activity, wide diversification is obtained; finally, there is a larger presence of monitors in sports entities (87.5%) and nursing homes (79.5%)

    3D reconstruction of magnetization from dichroic soft X-ray transmission tomography

    Get PDF
    The development of magnetic nanostructures for applications in spintronics requires methods capable of visualizing their magnetization. Soft X‐ray magnetic imaging combined with circular magnetic dichroism allows nanostructures up to 100–300 nm in thickness to be probed with resolutions of 20–40 nm. Here a new iterative tomographic reconstruction method to extract the three‐dimensional magnetization configuration from tomographic projections is presented. The vector field is reconstructed by using a modified algebraic reconstruction approach based on solving a set of linear equations in an iterative manner. The application of this method is illustrated with two examples (magnetic nano‐disc and micro‐square heterostructure) along with comparison of error in reconstructions, and convergence of the algorithm

    Prospectives of monitoring biological activity in a red-legged partridge incubator with a carbon dioxide probe

    Get PDF
    This study focuses on the relationship between CO2 production and the ultimate hatchability of the incubation. A total amount of 43316 eggs of red-legged partridge (Alectoris rufa) were supervised during five actual incubations: three in 2012 and two in 2013. The CO2 concentration inside the incubator was monitored over a 20-day period, showing sigmoidal growth from ambient level (428 ppm) up to 1700 ppm in the incubation with the highest hatchability. Two sigmoid growth models (logistic and Gompertz) were used to describe the CO2 production by the eggs, with the result that the logistic model was a slightly better fit (r2=0.976 compared to r2=0.9746 for Gompertz). A coefficient of determination of 0.997 between the final CO2 estimation (ppm) using the logistic model and hatchability (%) was found
    corecore