6,142 research outputs found

    Corporations and Economic Inequality Around the World: The Paradox of Hierarchy

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    Using time-series data from the US since 1950 and from 53 countries around the world in 2006, this chapter documents a strong negative relation between an economy’s employment concentration (that is, the proportion of the labor force employed by the largest 10, 25, or 50 firms) and its level of income inequality. Within the US, we find that trends in the relative size of the largest employers (up in the 1960s and 1970s, down in the 1980s and 1990s, up in the 2000s) are directly linked to changes in inequality, and that corporate size is a proximal cause of the extravagant increase in social inequality over the past generation. We conclude that organization theory can provide a distinctive contribution to understanding societal outcomes

    Resource Dependence Theory: Past and future

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    This chapter reviews the origins and primary arguments of resource dependence theory and traces its influence on the subsequent literatures in multiple social science and professional disciplines, contrasting it with Emerson\u27s power-dependence theory. Recent years have seen an upsurge in the theory\u27s citations in the literature, which we attribute in part to Stanford\u27s position of power in the network of academic exchange. We conclude with a review of some promising lines of recent research that extend and qualify resource dependence theory\u27s insights, and outline potentially fruitful areas of future research

    Evidence of an established population of Cherax quadricarinatus (von Martens, 1868) in south Texas, USA

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    Cherax quadricarinatus (von Martens, 1868) is a large parastacid crayfish (Decapoda: Parastacidae) native to Australia and Papua New Guinea. Due to various factors, C. quadricarinatus is an emerging invasive species in an increasing number of regions across the world. Deleterious ecological effects of C. quadricarinatus introduction have been documented in many of these regions, and its spread has been monitored and restricted where possible. Previously, only a small, isolated population of C. quadricarinatus in southern California had been reported within the continental United States. Here, we report the collection of three adult C. quadricarinatus from Brownsville, Cameron County, Texas, the first record of this species in the state and only the second record for the continental United States. Given the connectivity of aquatic habitats in the area and the duration for which the population has likely been present, there is evidence that C. quadricarinatus is poised to invade subtropical watersheds of the southern United States. The ecological effects of C. quadricarinatus on aquatic ecosystems in the region are not yet fully understood, but further research is warranted to effectively mitigate negative impacts that may occur and to guide efforts to manage or eradicate these population

    Unlocking Passion and Setting Students Free: The Impact of Culturally Relevant Writing Instruction in a Middle School English I Classroom

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    Culturally relevant writing instruction has the potential to validate the voices of students often not heard. Documented disparities in student writing proficiency in grades K-12 indicate a pressing need to employ more effective approaches in facilitating writing instruction. This paper presents the findings of a mixed methods research study that explored eighth grade English I students’ middle school reading and writing preferences, writing experiences, and the impact of culturally relevant writing instruction. Data were gathered from 63 students via reflective journals, writing interest forms, learning logs, and writing artifacts collected throughout a 3-week writing unit. Our findings reveal that writing instruction that leverages students’ interests, experiences, and cultural background has the potential to increase learning outcomes for students

    Identification of integrative and conjugative elements in pathogenic and commensal Neisseriaceae spp. via genomic distributions of DNA uptake sequence dialects

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    Mobile genetic elements (MGEs) are key factors responsible for dissemination of virulence determinants and antimicrobial-resistance genes amongst pathogenic bacteria. Conjugative MGEs are notable for their high gene loads donated per transfer event, broad host ranges and phylogenetic ubiquity amongst prokaryotes, with the subclass of chromosomally inserted integrative and conjugative elements (ICEs) being particularly abundant. The focus on a small number of model systems has biased the study of ICEs towards those conferring readily selectable phenotypes to host cells, whereas the identification and characterization of integrated cryptic elements remains challenging. Even though antimicrobial resistance and horizontally acquired virulence genes are major factors aggravating neisserial infection, conjugative MGEs of Neisseria gonorrhoeae and Neisseria meningitidis remain poorly characterized. Using a phenotype-independent approach based on atypical distributions of DNA uptake sequences (DUSs) in MGEs relative to the chromosomal background, we have identified two groups of chromosomally integrated conjugative elements in Neisseria: one found almost exclusively in pathogenic species possibly deriving from the genus Kingella, the other belonging to a group of Neisseria mucosa-like commensals. The former element appears to enable transfer of traditionally gonococcal-specific loci such as the virulence-associated toxin–antitoxin system fitAB to N. meningitidis chromosomes, whilst the circular form of the latter possesses a unique attachment site (attP) sequence seemingly adapted to exploit DUS motifs as chromosomal integration sites. In addition to validating the use of DUS distributions in Neisseriaceae MGE identification, the >170 identified ICE sequences provide a valuable resource for future studies of ICE evolution and host adaptation

    Georgia Academy of Science, University of North Georgia, March 15th-16th, 2019

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    The annual meeting of the Georgia Academy of Science took place March 15–16, 2019, at the University of North Georgia in Oakwood. The keynote speaker was Dr. Marguerite Madden, Professor in the University of Georgia\u27s Department of Geography and Director of the Center for Geospatial Research. Her presentation was entitled Geospatial Technologies and Augmented Reality Spark Excitement in Science Education, Research and Outreach. Additional presentations were provided by members of the Academy who represented the following sections: I. Biological Sciences, II. Chemistry, III. Earth & Atmospheric Sciences, IV. Physics, Mathematics, Computer Science, Engineering, & Technology, V. Biomedical Sciences, VI. Philosophy & History of Science, VII. Science Education, and VIII. Anthropology

    CD81 and claudin 1 coreceptor association: role in hepatitis C virus entry.

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    Hepatitis C virus (HCV) is an enveloped positive-stranded RNA hepatotropic virus. HCV pseudoparticles infect liver-derived cells, supporting a model in which liver-specific molecules define HCV internalization. Three host cell molecules have been reported to be important entry factors or receptors for HCV internalization: scavenger receptor BI, the tetraspanin CD81, and the tight junction protein claudin-1 (CLDN1). None of the receptors are uniquely expressed within the liver, leading us to hypothesize that their organization within hepatocytes may explain receptor activity. Since CD81 and CLDN1 act as coreceptors during late stages in the entry process, we investigated their association in a variety of cell lines and human liver tissue. Imaging techniques that take advantage of fluorescence resonance energy transfer (FRET) to study protein-protein interactions have been developed. Aequorea coerulescens green fluorescent protein- and Discosoma sp. red-monomer fluorescent protein-tagged forms of CD81 and CLDN1 colocalized, and FRET occurred between the tagged coreceptors at comparable frequencies in permissive and nonpermissive cells, consistent with the formation of coreceptor complexes. FRET occurred between antibodies specific for CD81 and CLDN1 bound to human liver tissue, suggesting the presence of coreceptor complexes in liver tissue. HCV infection and treatment of Huh-7.5 cells with recombinant HCV E1-E2 glycoproteins and anti-CD81 monoclonal antibody modulated homotypic (CD81-CD81) and heterotypic (CD81-CLDN1) coreceptor protein association(s) at specific cellular locations, suggesting distinct roles in the viral entry process

    Comparing life histories across taxonomic groups in multiple dimensions: how mammal-like are insects?

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    Explaining variation in life histories remains a major challenge because they are multi-dimensional and there are many competing explanatory theories and paradigms. An influential concept in life history theory is the ’fast-slow continuum’, exemplified by mammals. Determining the utility of such concepts across taxonomic groups requires comparison of the groups’ life histories in multidimensional space. Insects display enormous species richness and phenotypic diversity, but testing hypotheses like the ’fast-slow continuum’ has been inhibited by incomplete trait data. We use phylogenetic imputation to generate complete datasets of seven life history traits in orthopterans (grasshoppers and crickets) and examine the robustness of these imputations for our findings. Three phylogenetic principal components explain 83-96% of variation in these data. We find consistent evidence of an axis mostly following expectations of a ’fast-slow continuum’, except that ’slow’ species produce larger, not smaller, clutches of eggs. We show that the principal axes of variation in orthopterans and reptiles are mutually explanatory, as are those of mammals and birds. Essentially, trait covariation in Orthoptera, with ’slow’ species producing larger clutches, is more reptile-like than mammal-or-bird-like. We conclude that the ’fast-slow continuum’ is less pronounced in Orthoptera than in birds and mammals, reducing the universal relevance of this pattern, and the theories that predict it
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