to evaluate the effect of different rates of nitrogen fertilizer on competitive ability of canola (okapi cv.) in interference with wild mustard, a split-plot experiment based on a randomized complete block design with 3 replications was carried out at agricultural faculty of bu-ali sina university, in 2008-2009. 4 levels of nitrogen fertilization (100, 150, 200 and 250 kg n ha-1) were assigned ...

In this work lasers with micro-, nano-, pico- and femtosecond pulse durations were used to clean atmospheric corrosion products from the fragments of a 19th-century lead outdoor sculpture. The state surface was studied by optical microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy scanning electron microscopy. It shown that for all there is no self-limiting cleaning effect, metal d...

Methane ebullition (bubbling) from lake sediments is an important methane flux into the atmosphere. Previous studies have focused on open-water season, showing that temperature variations, pressure fluctuations, and wind-induced currents can affect ebullition. However, surveys during ice-cover are rare despite prevalence of seasonally ice-covered lakes, factors controlling poorly understood. He...

farming organic vegetable and crops have grown as a market desiring commodity. weed control in farms has been costly and laborous and it has always been hard to achieve a proper weeding. a few chemicals are commonly applied in organic farming. thermal weeding with flame burners seems a good solution; however, it has its own drawbacks, such as; damaging the main crops, low performance, being inf...

rangeland ecosystems shift across dynamic thresholds between differentecological states in response to natural or human-induced factors. these differentecological states are the result of interactions among climate, soils, grazing history,and management practices. the notion of a single ‘‘pristine’’ final state is onlyconceptual in nature, and because of this, dynamic thresholds and the effects...

we apply the two-sector production function developed by ram (1986) to estimate the threshold regression model for iran, concerning the effect of government size on economic growth. three government size indicators are used to find out the different threshold points. the results show a non-linear relationship of the armey curve in iran, in which the threshold effects corresponding to total gove...

Surface ozone (SOZ) can be very harmful if it exceeds the threshold limit. It can accumulate over sea and can return back to the land along with the breeze. Rural and vegetation rich areas often record elevated levels of surface ozone because of the variations in Volatile Organic Compound (VOC) levels, wind velocity and direction. Similarly methane is also an important greenhouse gas and plays ...

This paper examines the utility of the air pollution Model (TAPM) in simulating meteorology and dispersion of PM10 and wind data in order to assess The Impacts of Wind Variability Function on Urban Heat Island for the day of 25, November, 2012 in Karaj city that experienced severe degradation in air quality. Drawing, Skew-T diagrams, maps of surface pressure (500hp), omega (850hp) and atmosp...