817 research outputs found

    Effects of Group Living on Pupation in a Lady Beetle

    Get PDF
    To further understand the lives and development habits of insects, we must know how they influence each other through pupation periods. This will ultimately help us understand how interactive insects are throughout their life. To answer this question, we tested the pupation rates of Hippodamia convergens in groups and alone. This will help us delineate the advantages or disadvantages of the organism in groups versus singular pupation. We hypothesized that the Lady Beetles reared alone will develop faster and have a higher growth rate than those reared in groups. During the experiment, the subjects engaged in cannibalism which could have affected our results. Cannibalism occurs when food in the environment is scarce, and although the Lady Beetles were fed, the amounts that were given may not have been proper for their size nor consistent with each group member. At the end of this experiment we saw that the specimens reared in groups pupated more consistently than those reared alone. We assume that the reason Lady Beetles in groups pupated more consistently is because of the stressors in their environment, while the ones alone did not have any stressors. These conclusions may be important because it will help us determine the factors that influence pupation before and during the process in relation to other species of insects

    Getting Access Into the EU Market: A Coordination Challenge for the Brazilian Beef Chain

    Get PDF
    Brazil is the world beef export leader since 2004, when he Bovine Spongiform Encephalopathy (BSE) crisis in the United States and the severe draught in Australia dropped those countries beef exports and gave Brazilian beef chain a unique opportunity to enter in new markets. Brazil is facing now a major challenge in terms of aggregating value, since its export volume is already stabilizing. The European Union (EU) represents the most demanding market in terms of quality and one in which Brazil can get a better remuneration for its products, as long as the country beef chain can develop new relationship strategies to provide such a specific product. This study aims to present some trends in the European market as well as to discuss them as opportunities for the Brazilian beef chain, especially in terms of coordination forms, following New Institutional Economy principles. It shows that new forms of relationship within the network are emerging (like alliances and associations) and that new strategies should be focused on the consumer desires.Beef chain, Brazil, Relationship strategies, Coordination forms, International Relations/Trade, Livestock Production/Industries,

    Struggling for Brazil: Dutch, Portuguese and Spaniards in the 1640 Naval Battle of Paraíba

    Get PDF
    Over the years the 1640 naval battle of Paraíba (Brazil) has attracted the attention of several historians, including F.A. Varnhagen, H. Wätjen and J.C. Warnsinck, who made extensive use of Dutch sources. By combining the Dutch and Portuguese accounts, C.R. Boxer and, more recently, M.J. Guedes shed new light on the episode. The Portuguese material comprises the original papers of Fernando Mascarenhas, the commander in-chief of the armada. These papers are gathered in four voluminous codices and record events concerning the armada between April 1638 and October 1640. Written in Portuguese and Spanish, they comprise various documents, including correspondence, as well as instructions, reports, and minutes of meetings of the Council of Captains. The documents in these codices constitute the bedrock of this article which focuses on the armada leaders’ perceptions of their opponent during their sojourn in Brazil, a topic still insufficiently explored in the literature. Given the goal of the expedition, gathering information on the Dutch military and naval power was crucial for defining a strategy to oust them from Pernambuco. How did the armada leaders acquire intelligence? How reliable was it when cross-checked against other sources and to what extent did the outcome of the battle depend on it?Cities, Migration and Global Interdependenc

    Transferrin receptor expression and the regulation of placental iron uptake

    Get PDF
    Placental transferrin receptors, located at the apical side of syncytiotrophoblast, mediate placental iron uptake. Regulation of transferrin receptors on the fetal-maternal exchange area could be a major determinant in the regulation of trans-placental iron transport. Transferrin receptor expression in cultured human term cytotrophoblasts is on a much lower level than in choriocarcinoma cells, with a higher proportion of receptors located on the cell surface. Differentiation of cells, either due to longer culture periods or to 8-bromo-cAMP treatment does not lead to an increase of transferrin receptor expression. In vitro, the level of expression is largely regulated by the cellular density in the culture dishes. Low cellular occupancy of the dish leads to a high level of transferrin receptors. Treatment with iron-sources results in a down regulation of transferrin receptors. Thus, though the level of transferrin receptors in cultured normal trophoblast is at a constant level, unaffected by differentiation, high levels of maternal transferrin-iron availability can lead to a decrease in placental iron uptake. This feed-back mechanism makes placental iron uptake independent of maternal iron stores

    Estilos de vida en relación a la alimentación y hábitos alimentarios dentro y

    Get PDF
    Lobos, G (Lobos, German). Univ Talca, Fac Ciencias Empresariales, Escuela Ingn Comercial, Talca, ChileResumen Objetivo: Distinguir tipologías de consumidores en base a su estilo de vida en relación a la alimentación en las principales comunas de la Región Metropolitana de Santiago, Chile, y caracterizarlas según sus hábitos de consumo de alimentos dentro y fuera del hogar, características sociodemográficas y su nivel de satisfacción con su alimentación. Material y método: Se aplicó un cuestionario estructurado a una muestra de 951 personas en las principales comunas de la Región Metropolitana de Santiago (más de 100.000 habitantes). El instrumento de recogida de información incluyó una adaptación del cuestionario de estilos de vida en relación a la alimentación (FRL) y la escala SWFL (Satisfaction with Food-related Life). Se consultaron los hábitos de consumo de alimentos dentro y fuera del hogar y variables de clasificación sociodemográfica de los encuestados. Resultados: Mediante análisis cluster se distinguieron cinco tipologías con diferencias significativas en los cinco componentes obtenidos del FRL, con análisis factorial de componentes principales. Las tipologías presentaron distinto perfil de género, edad y nivel socioeconómico y difirieron en los puntajes obtenidos en la SWFL. Se diferenciaron en la frecuencia en que la persona almuerza, toma once y cena en su hogar. Respecto a las comidas fuera del hogar, las tipologías se distinguieron según la frecuencia de comidas en restaurantes, locales de comida rápida y en la compra de comida preparada. Conclusiones: Un estilo de vida en relación a la alimentación con baja implicación y disfrute de los alimentos se asocia con un mayor nivel socioeconómico y menor edad de las personas. Adicionalmente, se asocia con comportamientos alimentarios poco saludables y no beneficiosos para las personas, como una mayor frecuencia de comidas en restaurantes y de compra de comida preparada, junto a una menor frecuencia de comidas en el hogar, lo que estaría influyendo en un nivel inferior de satisfacción con la alimentación

    Surface Structure of Tetrahedral-Coordinated Amorphous Diamond-Like Carbon Films Grown by Pulsed Laser Deposition

    Get PDF
    The structure and composition of tetrahedral-coordinated amorphous diamond-like carbon films (a-tC) grown by pulsed laser deposition (PLD) of graphite has been studied with atomic force microscopy (AFM). The nanometer-scale surface structure has been studied as a function of growth parameters (e.g., laser energy density and film thickness) using contact-mode and tapping-mode AFM. Although the surfaces were found to be generally smooth, they exhibited reproducible structural features on several size scales which correlate with the variation of laser energy and th excited ion etching

    Clinical applications of pharmacogenomics

    Get PDF
    Indexación: Scopus.Pharmacogenomics is an emergent field aimed at tailoring pharmacological therapy. Genetic polymorphisms can modify the expression and function of enzymes and proteins involved in drug metabolism, affecting absorption, distribution, biotransformation and excretion as well as the drug-target interaction. Therefore, the presence of allelic variants will classify people as poor, extensive or rapid/ultra rapid metabolizers, modifying drug efficacy and safety. In this work, the state of art in relation to this discipline is presented and the genetic variants of enzymes that are involved in drug pharmacokinetics or pharmacodynamics are described. The effects of these variants on the therapeutic response to drugs used in our country are also discussed.http://ref.scielo.org/4y6n8

    Semitoric integrable systems on symplectic 4-manifolds

    Get PDF
    Let M be a symplectic 4-manifold. A semitoric integrable system on M is a pair of real-valued smooth functions J, H on M for which J generates a Hamiltonian S^1-action and the Poisson brackets {J,H} vanish. We shall introduce new global symplectic invariants for these systems; some of these invariants encode topological or geometric aspects, while others encode analytical information about the singularities and how they stand with respect to the system. Our goal is to prove that a semitoric system is completely determined by the invariants we introduce

    Bound Chains of Tilted Dipoles in Layered Systems

    Full text link
    Ultracold polar molecules in multilayered systems have been experimentally realized very recently. While experiments study these systems almost exclusively through their chemical reactivity, the outlook for creating and manipulating exotic few- and many-body physics in dipolar systems is fascinating. Here we concentrate on few-body states in a multilayered setup. We exploit the geometry of the interlayer potential to calculate the two- and three-body chains with one molecule in each layer. The focus is on dipoles that are aligned at some angle with respect to the layer planes by means of an external eletric field. The binding energy and the spatial structure of the bound states are studied in several different ways using analytical approaches. The results are compared to stochastic variational calculations and very good agreement is found. We conclude that approximations based on harmonic oscillator potentials are accurate even for tilted dipoles when the geometry of the potential landscape is taken into account.Comment: 10 pages, 6 figures. Submitted to Few-body Systems special issue on Critical Stability, revised versio
    corecore