نتایج جستجو برای: paleo ecology
تعداد نتایج: 54894 فیلتر نتایج به سال:
background: scorpions’ stings and their own mortalities place them among the most important health and medical problems. the dreadful features and especially their poisonous stings are considered a major cause of human stress and abhorrence/phobia. the current study aimed to study the scorpion fauna of ilam province, south western iran in order to manage scorpionism related problems. methods: i...
fuzzylogic computes a multi-criteria evaluation by means of either a boolean analysis, weightedlinear combination (wlc) and ordered weighted averaging (owa) of factor images. owa works withstandardized factor images and employs a variant of the wlc. it takes into account the risk associated withthe decision and degree of tradeoff associated with the variables in the analysis. in this research, ...
the changes in density and biomass of macrobenthos were seasonally investigated from winter 2005 till fall 2006 in southern caspian sea. samples were taken with a 225cm2 van veen grab from depths of 7 and 20 meters along two transects: line 8 area (western part) and radio darya area (eastern part). totally, 5 classes of macrobenthos were identified of which the most abundant populations were po...
Wildfire is a dominant disturbance agent in forest ecosystems, shaping important biogeochemical processes including net carbon (C) balance. Long-term monitoring and chronosequence studies highlight a resilience of biogeochemical properties to large, stand-replacing, high-severity fire events. In contrast, the consequences of repeated fires or temporal variability in a fire regime (e.g., the cha...
This paper primarily reviews our recent work on the biology and geochemistry of foraminifera with respect to their use as paleoceanographic proxies. Our approach to proxy validation and development is described, primarily from a modeler’s point of view. The approach is based on complementary steps in understanding the inorganic chemistry, inorganic isotope fractionation, and biological controls...
It was not known until recently whether the endemic of cholesterol gallstones among certain southwestern American Indian tribes was unique among this ethnic group. With use of ultrasonography of the gallbladder and standard diagnostic criteria, gallstones are now found in epidemic proportions in 13 diverse American Indian tribes and communities living in Arizona, Oklahoma, and the Dakotas. We s...
The precision of spectrophotometric measurements of indicator absorbance ratios is sufficient to allow evaluation of small isotopically induced differences in the dissociation constant of boric acid (KB). The quotient of KB and KB, obtained using isotopically X99% pure borate/boric acid buffers, provides an equilibrium constant for the reaction B(OH)3+ B(OH)4 3B(OH)3+ B(OH)4 which heretofore ha...
Pan-American mitochondrial DNA (mtDNA) haplogroup C1 has been recently subdivided into three branches, two of which (C1b and C1c) are characterized by ages and geographical distributions that are indicative of an early arrival from Beringia with Paleo-Indians. In contrast, the estimated ages of C1d--the third subset of C1--looked too young to fit the above scenario. To define the origin of this...
<!!!!!!!! THOMAS, E. and VAREKAMP, J.C, 1991. Paleo-environmental analyses of marsh sequences (Clinton, Connecticut): evidence for punctuated rise in relative sealevel during the latest Hol ocene. Journal of Coastal Research, SI #11, 125-158. Fort Lauderdale (Florida). ISSN 0749 0208. We developed an integrated chemical-faunal approach to paleo-environmental analysis of salt marsh sequences. Se...
Since reconnaissance work in the early 20th century, the existence of Pleistocene glaciers on Mount Taylor has been recognized in compilations of Rocky Mountain glaciation. This eroded composite volcano stands alone as the most prominent topographic element of the Colorado Plateau in west-central New Mexico. Its highest elevations, however, rise only a few hundred meters above the lowest late P...
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