286 research outputs found

    Factors modulating herbivory patterns in Cymodocea nodosa meadows

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    In coastal marine food webs, seagrass-grazer interactions play a fundamental role in ecological processes by regulating the structure and functioning of plant communities. Therefore, assessing the strength of these seagrass-grazer links and identifying the mechanisms that regulate these relationships are crucial to increasing our understanding of community and ecosystem structure and dynamics. Herbivory on the temperate seagrass Cymodocea nodosa was evaluated in four locations with contrasting abiotic and biotic factors (i.e., depth; meadow size; seagrass shoot density, productivity, and leaf traits; and herbivore presence) using cross-transplantation experiments carried out once per season to account for seasonal variation. Patterns of feeding rates on C. nodosa meadows showed high temporal variability, with peaks occurring in spring and summer. Results indicate that between 46.59% and 74.08% of the annual leaf production is lost to herbivory at the locations sampled in this study. Herbivory rates increased with higher nitrogen content and shoot density for all types of consumers (mesograzers, fishes, and sea urchins). This work highlights the need to integrate the abiotic and biotic factors modulating herbivory patterns, particularly in a foundation species like C. nodosa, for which changes in plant traits and grazer abundance may trigger trophic cascades with far-reaching consequences for associated species.This study was funded by the Spanish national project CTM2011-24482 (SEA-LIVE), by the Junta de Andalucia Excelence Project PRODESCA (P12-RNM-3020)) and by Ser-Cady project (FEDER-UCA18-107451) cofinanced by the 2014–2020 ERDF Operational Programme and by the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia. We thank Carmen Henares for field assistance

    Critical Casimir effect and wetting by helium mixtures

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    We have measured the contact angle of the interface of phase-separated 3^{3}He-4^{4}He mixtures against a sapphire window. We have found that this angle is finite and does not tend to zero when the temperature approaches TtT_t, the temperature of the tri-critical point. On the contrary, it increases with temperature. This behavior is a remarkable exception to what is generally observed near critical points, i.e. "critical point wetting''. We propose that it is a consequence of the "critical Casimir effect'' which leads to an effective attraction of the 3^{3}He-4^{4}He interface by the sapphire near TtT_{t}.Comment: submitted july 13 (2002), published march 20 (2003

    Taxing the Informal Economy: The Current State of Knowledge and Agendas for Future Research

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    This paper reviews the literature on taxation of the informal economy, taking stock of key debates and drawing attention to recent innovations. Conventionally, the debate on whether to tax has frequently focused on the limited revenue potential, high cost of collection, and potentially adverse impact on small firms. Recent arguments have increasingly emphasised the more indirect benefits of informal taxation in relation to economic growth, broader tax compliance, and governance. More research is needed, we argue, into the relevant costs and benefits for all, including quasi-voluntary compliance, political and administrative incentives for reform, and citizen-state bargaining over taxation

    International home economics

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    The conference was planned to serve the interests of those who wish to work in home economics programs abroad and those who are concerned with the education of international students in the universities and colleges of the United States. Approximately 165 home economists from other states and from foreign countries I including the African and Latin American countries I participated in the conference.https://lib.dr.iastate.edu/card_reports/1026/thumbnail.jp

    The Asset Portfolios of Native-Born and Foreign-Born Households

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    This paper analyses the net worth and asset portfolios of native- and foreign-born Australian families using HILDA (wave 2) data. Specifically, we estimate a system of asset equations with an adding-up constraint imposed to control for variation in households' total net worth. Our results indicate that after accounting for differences in human capital and income levels, single immigrants have a wealth advantage of almost 185,000relativetosinglenativebornindividuals.Althoughthewealthgapbetweenmixedandnativeborncouplesisnotstatisticallysignificant,immigrantonlycoupleshaveapproximately185,000 relative to single native-born individuals. Although the wealth gap between mixed and native-born couples is not statistically significant, immigrant-only couples have approximately 150,000 less wealth on average than native-born couples. Relative to equally wealthy native-born couples, immigrant-only couples hold substantially more of their wealth in their homes and less in the form of vehicles and financial assets. Mixed couples, on the other hand, allocate their wealth across assets in the same way as native-born couples

    Bush Encroachment Control and Risk Management in Semi-Arid Rangelands

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    We study the role of bush encroachment control for a farmer's income and income risk in a stochastic ecological-economic model of grazing management in semiarid rangelands. In particular, we study debushing as an instrument of risk management that complements the choice of an adaptive grazing management strategy for that sake. We show that debushing, while being a good practice for increasing the mean pasture productivity and thus expected income, also increases the farmer's income risk. The optimal extent of debushing for a risk-averse farmer is thus determined from balancing the positive and negative consequences of debushing on intertemporal and stochastic farm income

    Solution Structure of Kurtoxin: A Gating Modifier Selective for Cav3 Voltage-Gated Ca2+ Channels

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    How Well Does a Cash-Flow Tax on Wages Approximate an Economic Income Tax on Labor Income?

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    The recent German discussion has witnessed increasing interest in the Dual Income Tax. The analysis of its merits, as opposed to those of a comprehensive income tax, is usually conducted with the main argument of the increasing mobility of financial capital in mind. This article pursues an alternative route of reasoning, arguing that the composition of the tax base of labor income entails a differentiation of the tax rates on capital and labor income. The time effect inherent in this dualism causes allocational distortions of unknown magnitude. It is modeled employing effective tax rates. The extent of the divergence is determined empirically, using German cross-sectional data from the 2004 wave of the Socio-Economic Panel. The uneven distribution of this advantage across differently educated brackets of society is uncovered. The paper concludes with proposals to remedy the situation and a tentative endorsement of the Dual Income Tax
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