388 research outputs found

    The Status of Iowa\u27s Lepidoptera

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    Including strays, 122 species of butterflies have been confirmed in Iowa. However, since European settlement the populations of taxa of Iowa Lepidoptera have declined. While certain generalist species have experienced declines, species with life cycles that include native habitats, especially prairies and wetlands, have been particularly vulnerable. In a 1994 revision of the Iowa endangered and threatened species list, the Natural Resource Commission (NRC) listed two species of butterflies as endangered, five as threatened, and 25 as special concern, using general legal definitions of those rankings (NRC 1994). But after examining recent records, we have revised that list, using numbers of remaining sites as a scale of rarity. Of the 100 species of resident butterflies, one species is believed extirpated, eight are critically endangered, 15 are endangered, and 21 are threatened. Iowa\u27s moth fauna is poorly sampled but may show similar trends of decline in restricted habitats. Monitoring and habitat preservation efforts are ongoing. However, the effects of current efforts to manage lepidoptera populations are unproven and may even be detrimental. With continued habitat fragmentation, pesticide use, succession, and fire management, Lepidoptera diversity in Iowa is likely to continue to decline. Preservation of native remnants and management plans that recognize the key role of invertebrates are essential for the long-term health of remnant ecosystems

    Explaining Africa’s public consumption procyclicality : revisiting old evidence

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    This paper compiles a novel dataset of time-varying measures of government consumption cyclicality for a panel of 46 African economies between 1960 and 2014. Government consumption has, generally, been highly procyclical over time in this group of countries. However, sample averages hide serious heterogeneity across countries with the majority of them showing procyclical behavior despite some positive signs of graduation from the “procyclicality trap” in a few cases. By means of weighted least squares regressions, we find that more developed African economies tend to have a smaller degree of government consumption procyclicality. Countries with higher social fragmentation and those are more reliant on foreign aid inflows tend to have a more procyclical government consumption policy. Better governance promotes counter- cyclical fiscal policy whileincreased democracy dampens it. Finally, some fiscal rules are important in curbing the procyclical behavior of government consumption.info:eu-repo/semantics/publishedVersio

    How often does the Unruh-DeWitt detector click? Regularisation by a spatial profile

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    We analyse within first-order perturbation theory the instantaneous transition rate of an accelerated Unruh-DeWitt particle detector whose coupling to a massless scalar field on four-dimensional Minkowski space is regularised by a spatial profile. For the Lorentzian profile introduced by Schlicht, the zero size limit is computed explicitly and expressed as a manifestly finite integral formula that no longer involves regulators or limits. The same transition rate is obtained for an arbitrary profile of compact support under a modified definition of spatial smearing. Consequences for the asymptotic behaviour of the transition rate are discussed. A number of stationary and nonstationary trajectories are analysed, recovering in particular the Planckian spectrum for uniform acceleration.Comment: 30 pages, 1 figure. v3: Added references and minor clarification

    A cytoplasmic suppressor of a nuclear mutation affecting mitochondrial functions in Drosophila

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    Phenotypes relevant to oxidative phosphorylation (OXPHOS) in eukaryotes are jointly determined by nuclear and mitochondrial DNA (mtDNA). Thus, in humans, the variable clinical presentations of mitochondrial disease patients bearing the same primary mutation, whether in nuclear or mitochondrial DNA, have been attributed to putative genetic determinants carried in the other genome, though their identity and the molecular mechanism(s) by which they might act remain elusive. Here we demonstrate cytoplasmic suppression of the mitochondrial disease-like phenotype of the Drosophila melanogaster nuclear mutant tko25t, which includes developmental delay, seizure sensitivity, and defective male courtship. The tko25t strain carries a mutation in a mitoribosomal protein gene, causing OXPHOS deficiency due to defective intramitochondrial protein synthesis. Phenotypic suppression was associated with increased mtDNA copy number and increased mitochondrial biogenesis, as measured by the expression levels of porin voltage dependent anion channel and Spargel (PGC1α). Ubiquitous overexpression of Spargel in tko25t flies phenocopied the suppressor, identifying it as a key mechanistic target thereof. Suppressor-strain mtDNAs differed from related nonsuppressor strain mtDNAs by several coding-region polymorphisms and by length and sequence variation in the noncoding region (NCR), in which the origin of mtDNA replication is located. Cytoplasm from four of five originally Wolbachia-infected strains showed the same suppressor effect, whereas that from neither of two uninfected strains did so, suggesting that the stress of chronic Wolbachia infection may provide evolutionary selection for improved mitochondrial fitness under metabolic stress. Our findings provide a paradigm for understanding the role of mtDNA genotype in human disease

    Is life a thermal horizon ?

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    This talk aims at questioning the vanishing of Unruh temperature for an inertial observer in Minkovski spacetime with finite lifetime, arguing that in the non eternal case the existence of a causal horizon is not linked to the non-vanishing of the acceleration. This is illustrated by a previous result, the diamonds temperature, that adapts the algebraic approach of Unruh effect to the finite case.Comment: Proceedings of the conference DICE 2006, Piombino september 200

    A cytoplasmic suppressor of a nuclear mutation affecting mitochondrial functions in Drosophila

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    Phenotypes relevant to oxidative phosphorylation (OXPHOS) in eukaryotes are jointly determined by nuclear and mitochondrial DNA (mtDNA). Thus, in humans, the variable clinical presentations of mitochondrial disease patients bearing the same primary mutation, whether in nuclear or mitochondrial DNA, have been attributed to putative genetic determinants carried in the other genome, though their identity and the molecular mechanism(s) by which they might act remain elusive. Here we demonstrate cytoplasmic suppression of the mitochondrial disease-like phenotype of the Drosophila melanogaster nuclear mutant tko25t, which includes developmental delay, seizure sensitivity, and defective male courtship. The tko25t strain carries a mutation in a mitoribosomal protein gene, causing OXPHOS deficiency due to defective intramitochondrial protein synthesis. Phenotypic suppression was associated with increased mtDNA copy number and increased mitochondrial biogenesis, as measured by the expression levels of porin voltage dependent anion channel and Spargel (PGC1α). Ubiquitous overexpression of Spargel in tko25t flies phenocopied the suppressor, identifying it as a key mechanistic target thereof. Suppressor-strain mtDNAs differed from related nonsuppressor strain mtDNAs by several coding-region polymorphisms and by length and sequence variation in the noncoding region (NCR), in which the origin of mtDNA replication is located. Cytoplasm from four of five originally Wolbachia-infected strains showed the same suppressor effect, whereas that from neither of two uninfected strains did so, suggesting that the stress of chronic Wolbachia infection may provide evolutionary selection for improved mitochondrial fitness under metabolic stress. Our findings provide a paradigm for understanding the role of mtDNA genotype in human disease

    Selection Wages and Discrimination

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    Applicants for any given job are more or less suited to fill it, and the firm will select the best among them. Increasing the wage offer attracts more applicants and makes it possible to raise the hiring standard and improve the productivity of the staff. Wages that optimize on the trade-off between the wage level and the productivity of the workforce are known as selection wages. As men react more strongly to wage differentials than females, the trade-off is more pronounced for men and a profit-maximizing firm will offer a higher wage for men than for women in equilibrium

    On the Response of Particle Detectors in Vaidya Spacetimes

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    Using the formalism of the interaction picture we calculate an expression for the Wightman function for only the spherically symmetric modes of a quantum Klein-Gordon scalar field in a general Vaidya spacetime with ingoing null dust. It is demonstrated that particle detectors following time-like trajectories that are in the ground state at some time outside of the collapsing shell will respond independently from the configuration of the ingoing null dust if the response is taken at any time outside of the collapsing shell. For detectors that are taken to be in the ground state at a time interior to the shell it is shown that their response will depend on the configuration of the ingoing null dust. Relevance to the information loss paradox is discussed.Comment: 14 pages, 2 figure

    Spin-Hall-Active Platinum Thin Films Grown Via Atomic Layer Deposition

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    We study the magnetoresistance of yttrium iron garnet/Pt heterostructures in which the Pt layer was grown via atomic layer deposition (ALD). Magnetotransport experiments in three orthogonal rotation planes reveal the hallmark features of spin Hall magnetoresistance. We estimate the spin transport parameters by comparing the magnitude of the magnetoresistance in samples with different Pt thicknesses. We compare the spin Hall angle and the spin diffusion length of the ALD Pt layers to the values reported for high-quality sputter-deposited Pt films. The spin diffusion length of 1.5nm agrees well with platinum thin films reported in the literature, whereas the spin Hall magnetoresistance Δρ/ρ=2.2×105\Delta \rho / \rho = 2.2\times 10^{-5} is approximately a factor of 20 smaller compared to that of our sputter-deposited films. Our results demonstrate that ALD allows fabricating spin-Hall-active Pt films of suitable quality for use in spin transport structures. This work provides the basis to establish conformal ALD coatings for arbitrary surface geometries with spin-Hall-active metals and could lead to 3D spintronic devices in the future.Comment: 11 pages, 3 figure

    Microbiota in health and disease-potential clinical applications

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    Within the last two decades tremendous efforts in biomedicine have been undertaken to understand the interplay of commensal bacteria living in and on our human body with our own human physiology. It became clear that (1) a high diversity especially of the microbial communities in the gut are important to preserve health and that (2) certain bacteria via nutrition-microbe-host metabolic axes are beneficially affecting various functions of the host, including metabolic control, energy balance and immune function. While a large set of evidence indicate a special role for small chain fatty acids (SCFA) in that context, recently also metabolites of amino acids (e.g., tryptophan and arginine) moved into scientific attention. Of interest, microbiome alterations are not only important in nutrition associated diseases like obesity and diabetes, but also in many chronic inflammatory, oncological and neurological abnormalities. From a clinician's point of view, it should be mentioned, that the microbiome is not only interesting to develop novel therapies, but also as a modifiable factor to improve efficiency of modern pharmaceutics, e.g., immune-therapeutics in oncology. However, so far, most data rely on animal experiments or human association studies, whereas controlled clinical intervention studies are spare. Hence, the translation of the knowledge of the last decades into clinical routine will be the challenge of microbiome based biomedical research for the next years. This review aims to provide examples for future clinical applications in various entities and to suggest bacterial species and/or microbial effector molecules as potential targets for intervention studies
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