air pollution as a predictor of mortality in a prospective study of US adults. Response to Loomis et al. I would like to address comments of Loomis et al. about inferences drawn from studies using group-level exposure variables , the use of the tobacco analogy, the application of Hill's criteria for causality (1), and the use of the Hertz-Picciotto criteria for evaluating studies (2). Whether t...

Divergent results from ecologic and analytic studies on residential radon and lung cancer have created uncertainty in terms of risk assessment. The authors performed concurrent analyses on individual and aggregated data from the nationwide case-control study of residential radon and lung cancer in Sweden. For data aggregated on the county level, the ecologic excess relative risk estimates per 1...

Divergent results from ecologic and analytic studies on residential radon and lung cancer have created uncertainty in terms of risk assessment. The authors performed concurrent analyses on individual and aggregated data from the nationwide case-control study of residential radon and lung cancer in Sweden. For data aggregated on the county level, the ecologic excess relative risk estimates per 1...

abiotic factors, as topographic and physicochemical properties of soil, are the most important effective factor on vegetation in rangeland ecosystems which have the most important performances to forming and succession of plant vegetation. ecologic management of rangelands can be desired by better understanding of these effective factors. then, rangeland of javaherdeh (ramsar) in the northern a...

We introduce a symbolic representation like set theory to consider ecologic interactions between species (ECOSET). The ecologic exclusion principle (Gause) is put in a symbolic way and used as operational tool to consider more complex cases like interaction with sterile species (SIT technique), two species with two superposed sources (niche differentiation) and N+P species competing by N resour...