449 research outputs found

    To Ban or Not to Ban: Foreign Lobbying and Cross National Externalities

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    This paper studies the costs and benefits of foreign lobbying. We show how and when foreign lobbying can help internalize cross national externalities. We argue that this is an often overlooked benefit of foreign lobbying. We also study under what conditions a constitutional rule banning foreign lobbying is in the national interest of a country. A key factor in this calculus is whether the interests of foreign lobby groups and domestic unorganized groups coincide or not. We illustrate the logic with examples from trade policy and environmental regulation

    T-bet controls intestinal mucosa immune responses via repression of type 2 innate lymphoid cell function

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    Innate lymphoid cells (ILCs) play an important role in regulating immune responses at mucosal surfaces. The transcription factor T-bet is crucial for the function of ILC1s and NCR+ ILC3s and constitutive deletion of T-bet prevents the development of these subsets. Lack of T-bet in the absence of an adaptive immune system causes microbiota-dependent colitis to occur due to aberrant ILC3 responses. Thus, T-bet expression in the innate immune system has been considered to dampen pathogenic immune responses. Here, we show that T-bet plays an unexpected role in negatively regulating innate type 2 responses, in the context of an otherwise intact immune system. Selective loss of T-bet in ILCs leads to the expansion and increased activity of ILC2s, which has a functionally important impact on mucosal immunity, including enhanced protection from Trichinella spiralis infection and inflammatory colitis. Mechanistically, we show that T-bet controls the intestinal ILC pool through regulation of IL-7 receptor signalling. These data demonstrate that T-bet expression in ILCs acts as the key transcriptional checkpoint in regulating pathogenic vs. protective mucosal immune responses, which has significant implications for the understanding of the pathogenesis of inflammatory bowel diseases and intestinal infections

    Contrasted histories of organelle and nuclear genomes underlying physiological diversification in a grass species

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    C4 photosynthesis evolved multiple times independently in angiosperms, but most origins are relatively old so that the early events linked to photosynthetic diversification are blurred. The grass Alloteropsis semialata is an exception, as this species encompasses C4 and non-C4 populations. Using phylogenomics and population genomics, we infer the history of dispersal and secondary gene flow before, during and after photosynthetic divergence in A. semialata. We further analyse the genome composition of individuals with varied ploidy levels to establish the origins of polyploids in this species. Detailed organelle phylogenies indicate limited seed dispersal within the mountainous region of origin and the emergence of a C4 lineage after dispersal to warmer areas of lower elevation. Nuclear genome analyses highlight repeated secondary gene flow. In particular, the nuclear genome associated with the C4 phenotype was swept into a distantly related maternal lineage probably via unidirectional pollen flow. Multiple intraspecific allopolyploidy events mediated additional secondary genetic exchanges between photosynthetic types. Overall, our results show that limited dispersal and isolation allowed lineage divergence, with photosynthetic innovation happening after migration to new environments, and pollen-mediated gene flow led to the rapid spread of the derived C4 physiology away from its region of origin

    The Effect of Chemical Information on the Spatial Distribution of Fruit Flies: II Parameterization, Calibration, and Sensitivity

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    In a companion paper (Lof et al., in Bull. Math. Biol., 2008), we describe a spatio-temporal model for insect behavior. This model includes chemical information for finding resources and conspecifics. As a model species, we used Drosophila melanogaster, because its behavior is documented comparatively well

    Measurement of 7Li(n,γ0)8Li cross sections at En=1.5-1340 eV

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    The 7Li(n,γ)8Li cross section is important in inhomogeneous big bang models, and as a constraint on model parameters used to determine the solar 7Be(p,γ)8B reaction rate. Values of the 7Li(n,γ0)8Li reaction cross section were measured for neutron energies between 1.5 and 1340 eV at the Oak Ridge Electron Linear Accelerator. The normalization of the cross section was determined by measuring the gamma-ray yield from the 7Li(n,γ0)8Li reaction relative to that from the 10B(n,αγ)7Li reaction. The cross section was found to have the inverse neutron-velocity relationship (1/υ) indicative of s-wave capture. These results help resolve ambiguities in previous measurements

    The Effect of Chemical Information on the Spatial Distribution of Fruit Flies: I Model Results

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    Animal aggregation is a general phenomenon in ecological systems. Aggregations are generally considered as an evolutionary advantageous state in which members derive the benefits of protection and mate choice, balanced by the costs of limiting resources and competition. In insects, chemical information conveyance plays an important role in finding conspecifics and forming aggregations. In this study, we describe a spatio-temporal simulation model designed to explore and quantify the effects of these infochemicals, i.e., food odors and an aggregation pheromone, on the spatial distribution of a fruit fly (Drosophila melanogaster) population, where the lower and upper limit of local population size are controlled by an Allee effect and competition. We found that during the spatial expansion and strong growth of the population, the use of infochemicals had a positive effect on population size. The positive effects of reduced mortality at low population numbers outweighed the negative effects of increased mortality due to competition. At low resource densities, attraction toward infochemicals also had a positive effect on population size during recolonization of an area after a local population crash, by decreasing the mortality due to the Allee effect. However, when the whole area was colonized and the population was large, the negative effects of competition on population size were larger than the positive effects of the reduction in mortality due to the Allee effect. The use of infochemicals thus has mainly positive effects on population size and population persistence when the population is small and during the colonization of an area

    Low dispersal and ploidy differences in a grass maintain photosynthetic diversity despite gene flow and habitat overlap

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    Geographical isolation facilitates the emergence of distinct phenotypes within a single species, but reproductive barriers or selection is needed to maintain the polymorphism after secondary contact. Here, we explore the processes that maintain intraspecific variation of C4 photosynthesis, a complex trait that results from the combined action of multiple genes. The grass Alloteropsis semialata includes C4 and non‐C4 populations, which have co‐existed as a polyploid series for more than one million years in the miombo woodlands of Africa. Using population genomics, we show that there is genome‐wide divergence for the photosynthetic types, but the current distribution does not reflect a simple habitat displacement scenario as the genetic clusters overlap, being occasionally mixed within a given habitat. Despite evidence of recurrent introgression between non‐C4 and C4, in both diploids and polyploids, the distinct genetic lineages retain their identity, potentially because of selection against hybrids. Coupled with strong isolation by distance within each genetic group, this selection created a geographical mosaic of photosynthetic types. Diploid C4 and non‐C4 types never grew together, and the C4 type from mixed populations constantly belonged to the hexaploid lineage. By limiting reproductive interactions between photosynthetic types, the ploidy difference likely allows their co‐occurrence, reinforcing the functional diversity within this species. Together, these factors enabled the persistence of divergent physiological traits of ecological importance within a single species despite gene flow and habitat overlap

    Champion and audit and feedback strategy fidelity and their relationship to depression intervention fidelity: A mixed method study

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    Background: Globally, mental health disorders rank as the greatest cause of disability. Low and middle-income countries (LMICs) hold a disproportionate share of the mental health burden, especially as it pertains to depression. Depression is highly prevalent among those with non-communicable diseases (NCDs), creating a barrier to successful treatment. While some treatments have proven efficacy in LMIC settings, wide dissemination is challenged by multiple factors, leading researchers to call for implementation strategies to overcome barriers to care provision. However, implementation strategies are often not well defined or documented, challenging the interpretation of study results and the uptake and replication of strategies in practice settings. Assessing implementation strategy fidelity (ISF), or the extent to which a strategy was implemented as designed, overcomes these challenges. This study assessed fidelity of two implementation strategies (a ‘basic’ champion strategy and an ‘enhanced’ champion ​+ ​audit and feedback strategy) to improve the integration of a depression intervention, measurement based care (MBC), at 10 NCD clinics in Malawi. The primary goal of this study was to assess the relationship between the implementation strategies and MBC fidelity using a mixed methods approach. Methods: We developed a theory-informed mixed methods fidelity assessment that first combined an implementation strategy specification technique with a fidelity framework. We then created corresponding fidelity indicators to strategy components. Clinical process data and one-on-one in-depth interviews with 45 staff members at 6 clinics were utilized as data sources. Our final analysis used descriptive statistics, reflexive-thematic analysis (RTA), data merging, and triangulation to examine the relationship between ISF and MBC intervention fidelity. Results: Our mixed methods analysis revealed how ISF may moderate the relationship between the strategies and MBC fidelity. Leadership engagement and implementation climate were critical for clinics to overcome implementation barriers and preserve implementation strategy and MBC fidelity. Descriptive statistics determined champion strategy fidelity to range from 61 to 93% across the 10 clinics. Fidelity to the audit and feedback strategy ranged from 82 to 91% across the 5 clinics assigned to that condition. MBC fidelity ranged from 54 to 95% across all clinics. Although correlations between ISF and MBC fidelity were not statistically significant due to the sample of 10 clinics, associations were in the expected direction and of moderate effect size. A coefficient for shared depression screening among clinicians had greater face validity compared to depression screening coverage and functioned as a proximal indicator of implementation strategy success. Conclusion: Fidelity to the basic and enhanced strategies varied by site and were influenced by leadership engagement and implementation climate. Champion strategies may benefit from the addition of leadership strategies to help address implementation barriers outside the purview of champions. ISF may moderate the relationship between strategies and implementation outcomes
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