131 research outputs found

    Flying In The Face Of Efficiency: Migratory Swallows (Hirundinidae) Have Less Pointed Wings Than Residents

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    The correlation between migration and more pointed wings is a well-established pattern in avian ecomorphology, and has been supported by a large number of studies over many decades. However, most studies have focused on taxa with relatively low aspect ratio wings, and taxa with high aspect ratio wings have scarcely been investigated except as part of large pooled datasets. While some authors have questioned whether the pattern is detectable in all taxa, the basic assumption that migrants have more pointed or similar wings compared to residents -- depending on the strength of selection -- has not been questioned. This study examines the correlation between migration and more pointed wings in swallows (Hirundinidae), a family with relatively high aspect ratio wings. Using phylogenetically controlled statistical methods and a well-established index of wing pointedness, I investigated the wing shape of species pairs from eight swallow genera. The present study establishes that among swallows, migratory species have less pointed wings than sedentary species, and that wing pointedness declines linearly with increasing migration distance. This study represents the first published result demonstrating a reversal of the correlation between migration and more pointed wings found in other avian taxa. Hypotheses to account for this unprecedented finding and implications for future research are discussed

    Spillovers from US monetary policy: Evidence from a time-varying parameter global vector autoregressive model

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    The paper develops a global vector auto-regressive model with time varying pa- rameters and stochastic volatility to analyse whether international spillovers of US monetary policy have changed over time. The model proposed enables us to assess whether coefficients evolve gradually over time or are better characterized by infrequent, but large, breaks. Our find- ings point towards pronounced changes in the international transmission of US monetary policy throughout the sample period, especially so for the reaction of international output, equity prices and exchange rates against the US dollar. In general, the strength of spillovers has weakened in the aftermath of the global financial crisis. Using simple panel regressions, we link the vari- ation in international responses to measures of trade and financial globalization. We find that a broad trade base and a high degree of financial integration with the world economy tend to cushion risks stemming from a foreign shock such as US tightening of monetary policy, whereas a reduction in trade barriers and/or a liberalization of the capital account increase these risks

    US Monetary Policy in a Globalized World

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    We analyze the interaction between monetary policy in the US and the global economy proposing a new class of Bayesian global vector autoregressive models that accounts for time-varying parameters and stochastic volatility (TVP-SV-GVAR). Our results suggest that US monetary policy responds to shocks to the global economy, in particular to global aggregate demand and monetary policy shocks. On the other hand, US-based contractionary monetary policy shocks lead to persistent international output contractions and a drop in global inflation rates, coupled with rising interest rates in advanced economies and a real depreciation of currencies with respect to the US dollar. We find considerable evidence for heterogeneity in the spillovers across countries, as well for changes in the transmission of monetary policy shocks over time.Series: Department of Economics Working Paper Serie

    Growing Together? Projecting Income Growth in Europe at the Regional Level

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    In this paper we present an econometric framework aimed at obtaining projections of income growth in Europe at the regional level. We account for model uncertainty in terms of the choice of explanatory variables, as well as the nature of the spatial spillovers of output growth and human capital investment. Building on recent advances in Bayesian model averaging, we construct projected trajectories of income and human capital simultaneously, while integrating out the effects of other covariates. This approach allows us to assess the potential contribution of future educational attainment to economic growth and income convergence among European regions over the next decades. Our findings suggest that income convergence dynamics and human capital act as important drivers of income growth for the decades to come. In addition we find that the relative return of improving educational attainment levels in terms of economic growth appears to be higher in peripheral European regions. (authors' abstract)Series: Department of Economics Working Paper Serie

    Acanalonia conica (Say, 1830) and three other true hopper species new for Austria (Hemiptera: Auchenorrhyncha)

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    Acanalonia conica (Say, 1830) und drei weitere Zikadenarten neu fĂŒr Österreich (Hemiptera: Auchenorrhyncha). – Drei Neozoen, Acanalonia conica (Say, 1830), Aplos simplex (Germar, 1830) und Hishimonus hamatus Kuoh, 1976 wurden in einer GĂ€rtnerei in Graz erstmals fĂŒr Österreich nachgewiesen. Sie wurden wahrscheinlich mit ZierstrĂ€uchern aus Italien importiert. Ein weiterer Erstnachweis betrifft Chiasmus conspurcatus (Perris, 1857). Diese Art ist heimisch und wurde an zwei Salzlacken des Nationalparks Neusiedlersee-Seewinkel nachgewiesen. Eine Gesamtliste jener 71 Zikadenarten, die an den beiden Lacken gefunden wurden, wird ebenfalls vorgelegt.  Acanalonia conica (Say, 1830), Aplos simplex (Germar, 1830) and Hishimonus hamatus Kuoh, 1976 are three alien species reported for the first time from Austria. They were found in a garden centre in Graz and presumably imported with ornamental shrubs from Italy. Another first record is Chiasmus conspurcatus (Perris, 1857), an indigenous species found in the Neusiedlersee-Seewinkel National Park. In addition, we present a list of 71 Auchenorrhyncha species found at the two inland salt marshes, where C. conspurcatus occurs

    Periodical Maintenance of Forest Roads with a Mobile Stone Crusher

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    Forest road networks are exposed to damage by traffic, climate, timber harvesting and vegetation. To maintain their functionality, they must be maintained regularly. Periodical maintenance is required when the forest road surface layer is deteriorated and eroded. Well-graded material is required for replacing the forest road surface and often has to be sourced from gravel storage areas, which is costly and requires a large number of truck trips. Therefore, converting non-graded aggregate available on site into well-graded aggregate with a mobile stone crusher is considered a viable alternative. The present study was carried out during a periodical maintenance treatment at the Bavarian State Forest Enterprise and the effect of employing a mobile stone crusher was evaluated with regard to (1) forest road load bearing capacity development during a one-year period posttreatment, (2) particle size distribution of the surface layer material before and after crushing, and (3) its cost compared to other alternatives. Samples were collected pre- and post-operation for particle size distribution analysis, load bearing capacity was measured repeatedly with a light falling weight deflectometer and compared to an untreated reference section and cost of the treatment was compared to two alternatives. The mobile stone crusher was capable of reducing the non-graded to well-graded/close-to-wellgraded material and particle size distributions aligned well with the recommendations for lime-water bonded surfaces. Load bearing capacity exceeded the threshold of 40 MN m–2 (Evd, elastic modulus dynamic) for primary forest roads at all times. It increased significantly after the treatment and remained on a significantly higher level throughout the following year. Absolute and relative increases were higher than on the untreated reference section. The treatment variant involving a mobile stone crusher and material available on site was substantially cheaper (5.31 € m-1) than to supply non-graded (16.29 € m-1) or well-graded (19.82 € m–1) material by truck. Material and transport costs represented 67% and 82% of the total costs in the latter two cases. It can be concluded that mobile stone crushers are capable of producing at least close-to-well-graded forest road surface aggregate and that forest road load bearing capacity can be significantly and lastingly increased at only a part of the costs of the alternatives. A maximum of cost and resource efficiency and environmental soundness can be attained when enough surface aggregate is available on site. If this is not the case, sourcing nongraded material as local as possible is the next best alternative

    Hemiptera records from Lake Spechtensee and from Southern Styria (Austria)

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    Hemiptera records gained in July 2015 in course of the 7th European Hemiptera Congress in Styria are presented. In total, 144 Auchenorrhyncha, 143 Heteroptera, 13 Psylloidea and 2 Aphididae species were collected. Ribautodelphax imitans (Delphacidae), Eurhadina saageri (Cicadellidae), Notonecta maculata (Notonectidae), Notonecta meridionalis (Notonectidae) and Polymerus cognatus (Miridae) are new records for Styria

    Low Variation in the Polymorphic Clock Gene Poly-Q Region Despite Population Genetic Structure across Barn Swallow (Hirundo rustica) Populations

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    Recent studies of several species have reported a latitudinal cline in the circadian clock gene, Clock, which influences rhythms in both physiology and behavior. Latitudinal variation in this gene may hence reflect local adaptation to seasonal variation. In some bird populations, there is also an among-individual association between Clock poly-Q genotype and clutch initiation date and incubation period. We examined Clock poly-Q allele variation in the Barn Swallow (Hirundo rustica), a species with a cosmopolitan geographic distribution and considerable variation in life-history traits that may be influenced by the circadian clock. We genotyped Barn Swallows from five populations (from three subspecies) and compared variation at the Clock locus to that at microsatellite loci and mitochondrial DNA (mtDNA). We found very low variation in the Clock poly-Q region, as >96% of individuals were homozygous, and the two other alleles at this locus were globally rare. Genetic differentiation based on the Clock poly-Q locus was not correlated with genetic differentiation based on either microsatellite loci or mtDNA sequences. Our results show that high diversity in Clock poly-Q is not general across avian species. The low Clock variation in the background of heterogeneity in microsatellite and mtDNA loci in Barn Swallows may be an outcome of stabilizing selection on the Clock locus

    Extensive Regulation of Diurnal Transcription and Metabolism by Glucocorticoids.

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    Altered daily patterns of hormone action are suspected to contribute to metabolic disease. It is poorly understood how the adrenal glucocorticoid hormones contribute to the coordination of daily global patterns of transcription and metabolism. Here, we examined diurnal metabolite and transcriptome patterns in a zebrafish glucocorticoid deficiency model by RNA-Seq, NMR spectroscopy and liquid chromatography-based methods. We observed dysregulation of metabolic pathways including glutaminolysis, the citrate and urea cycles and glyoxylate detoxification. Constant, non-rhythmic glucocorticoid treatment rescued many of these changes, with some notable exceptions among the amino acid related pathways. Surprisingly, the non-rhythmic glucocorticoid treatment rescued almost half of the entire dysregulated diurnal transcriptome patterns. A combination of E-box and glucocorticoid response elements is enriched in the rescued genes. This simple enhancer element combination is sufficient to drive rhythmic circadian reporter gene expression under non-rhythmic glucocorticoid exposure, revealing a permissive function for the hormones in glucocorticoid-dependent circadian transcription. Our work highlights metabolic pathways potentially contributing to morbidity in patients with glucocorticoid deficiency, even under glucocorticoid replacement therapy. Moreover, we provide mechanistic insight into the interaction between the circadian clock and glucocorticoids in the transcriptional regulation of metabolism
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