introduction: verapamil, a phenylalkylamin –type ca2+ channel blocker, is widely used in the treatment of cardiovascular disorders especially as an antiaryhthmic and antiangina agent. theoretically, calcium can influence thyroid function and there are evidences that ca2+ channel blockers are able to interfere with thyroid function. in this study, the effects of chronic oral administration of ve...

introduction: the growth of agricultural production and natural resources are from primary objectives of any political system, because this section has a vital role in providing food security. according to the production theories, production growth will come from two sources; more use of production factors within the framework of existing technologies and second, with using more advanced and mo...

Nick M. Haddad, David Tilman and Johannes M. H. Knops Department of Ecology, 1987 Upper Buford Circle, University of Minnesota, St. Paul, MN 55108, USA Correspondence and present address: Department of Zoology, Box 7617, North Carolina State University, Raleigh, NC 27695±7617. E-mail: [email protected]. Tel.:+1 919-515-4588, Fax: +1 919-515-5327 Department of Biological Sciences, University ...

High temperature anomalies have recently been shown to have adverse impacts on multiple health and socio-economic outcomes. A well established literature on the impacts of early life stress on life-long human capital accumulation has led us to hypothesize that high temperature anomalies can have long-term impacts on economic productivity. Using data on historical weather and the earnings, place...

Plant diversity and niche complementarity had progressively stronger effects on ecosystem functioning during a 7-year experiment, with 16-species plots attaining 2.7 times greater biomass than monocultures. Diversity effects were neither transients nor explained solely by a few productive or unviable species. Rather, many higher-diversity plots outperformed the best monoculture. These results h...

Increasing aridity and drought severity forecast for many land areas could reduce the land carbon (C) sink. However, with limited long-term direct measures, it is difficult to distinguish direct drying effects from counter effects of CO2 enrichment and nitrogen (N) deposition. Here, we document a >50% decline in production of a native C3 grassland over four decades and assign the forcing and ti...

The spatial concentration of ideas is central to economic geography. Yet, how proximity to research affects productivity is not well studied. We use the late 19th century establishment of agricultural experiment stations in the United States to estimate the importance of proximity to research for productivity growth. Our analysis of county-level agricultural census data from 1870 to 2000 reveal...

Experimental studies have observed Long Term synaptic Potentiation (LTP) when a presynaptic neuron fires shortly before a postsynaptic neuron, and Long Term Depression (LTD) when the presynaptic neuron fires shortly after, a phenomenon known as Spike Timing Dependent Plasticity (STDP). When a neuron is presented successively with discrete volleys of input spikes STDP has been shown to learn 'ea...

A new behavioral training approach has been found significantly to improve visual function; the results further attest to the high degree of plasticity in sensory systems.