Reconstruction of aridity for the Sierra de la Laguna, Baja California Sur, Mexico

A well-documented history of past climatic conditions is needed to understand and resolve some ecological problems, but the existing climatological records are too short to detect long-term climatic variability and changes. Some trees, such as pines, produce annual tree rings with different widths depending on prevailing environmental conditions, such as climate. Tree-ring analysis of long-lived trees can be used to estimate past variations in climate. The principal aim of this study is to reconstruct aridity for the southern portion of the Baja California Peninsula, by means of dendroclimatologic techniques.

Bioenergetics of the freshwater prosobranch Idiopoma angularis Muller in Laguna de Bay

This study was made as an attempt to investigate some of the ecological aspects of the freshwater snail Idiopoma angularis Muller in a modern framework of energy flow and mathematical models. It offers the first investigation of respiration (as related to temperature and body size), production (growth), and excretion in the prosobranch I. angularis in Laguna Lake.

Natural streamflow regime alterations: Damming of the Piave river basin (Italy)

A novel approach is proposed to estimate the natural streamflow regime of a river and to assess the extent of the alterations induced by dam operation related to anthropogenic (e.g., agricultural, hydropower) water uses in engineered river basins. The method consists in the comparison between the seasonal probability density function (pdf) of observed streamflows and the purportedly natural streamflow pdf obtained by a recently proposed and validated probabilistic model. The model employs a minimum of landscape and climate parameters and unequivocally separates the effects of anthropogenic regulations from those produced by hydroclimatic fluctuations. The approach is applied to evaluate the extent of the alterations of intra-annual streamflow variability in a highly engineered alpine catchment of north-eastern Italy, the Piave river. Streamflows observed downstream of the regulation devices in the Piave catchment are found to exhibit smaller means/modes, larger coefficients of variation, and more pronounced peaks than the flows that would be observed in the absence of anthropogenic regulation, suggesting that the anthropogenic disturbance leads to remarkable reductions of river flows, with an increase of the streamflow variability and of the frequency of preferential states far from the mean. Some structural limitations of management approaches based on minimum streamflow requirements (widely used to guide water policies) as opposed to criteria based on whole distributions are also discussed. Copyright © 2010 by the American Geophysical Union.

Semifactual: Byrne's account of even-if

Byrne's approach to the semifactual conditional captures the reasoning data. However, we argue that it does not account for the processes or Principles by which people arrive at representations of even-if conditionals, upon which their reasoning is said to be based. Drawing upon recent work on the suppositional conditional we present such an account.