Many recent studies have focused on the relationship between biodiversity and ecosystem functioning, such as investigations into the productivity of experimental plant communities. One of the central issues affecting the functioning of ecosystems is the diversity of resident species richness and the composition of the plant community. However, one challenge to experimental studies is that resul...

A pre®iously described molecular-thermodynamic framework, based on colloid theory, is used to correlate experimental asphaltene-precipitation data at high-temperature and pressure conditions. In this framework, asphaltenes and resins are represented by pseudopure components, and all other components in a crude oil are presented by a continuous medium that affects ®an der Waals attractions among...

in this study some thermodynamic parameters including freezing point, boiling point and the vapor pressure of urmia lake salt water were investigated as some important environmentally monitored physicochemical properties of urmia lake. in this regard salt concentration is chiefly responsible for the modification of the thermodynamic properties of urmia lake water which affects its overall envir...

Species assemblage in a local community is determined by the interplay of evolutionary and ecological processes. The Tropical Niche Conservatism hypothesis proposes mechanisms underlying patterns of biodiversity in biological communities along environmental gradients. This hypothesis predicts that, among other things, clades in areas with warm or wet environments are, on average, older than tho...

Water and its influence on plants likely exerted strong adaptive pressures in human evolution. Understanding relationships among water, plants, and early humans is limited both by incomplete terrestrial records of environmental change and by indirect proxy data for water availability. Here we present a continuous record of stable hydrogen-isotope compositions (expressed as δD values) for lipid ...

An ultrasonic technique, invariant to temperature changes, for a density measurement of different liquids under in situ extreme conditions is presented. The influence of geometry and material parameters of the measurement system (transducer, waveguide, matching layer) on measurement accuracy and reliability is analyzed theoretically along with experimental results. The proposed method is based ...

in this research, the correlation between precipitation change in southern coasts of caspian sea and variability of sea level pressure have been analyzed by using environmental to circulation approach at time period 1339- 1383. in this respect, we make use of daily precipitation data of the 12 synoptic stations of studied area at surface data base section and prepare the time series matrix of p...