Event Characteristics (event + characteristic)

Distribution by Scientific Domains

Selected Abstracts

First-year post-fire erosion rates in Bitterroot National Forest, Montana,

Kevin M. Spigel
Abstract Accelerated runoff and erosion commonly occur following forest fires due to combustion of protective forest floor material, which results in bare soil being exposed to overland flow and raindrop impact, as well as water repellent soil conditions. After the 2000 Valley Complex Fires in the Bitterroot National Forest of west-central Montana, four sets of six hillslope plots were established to measure first-year post-wildfire erosion rates on steep slopes (greater than 50%) that had burned with high severity. Silt fences were installed at the base of each plot to trap eroded sediment from a contributing area of 100 m2. Rain gauges were installed to correlate rain event characteristics to the event sediment yield. After each sediment-producing rain event, the collected sediment was removed from the silt fence and weighed on site, and a sub-sample taken to determine dry weight, particle size distribution, organic matter content, and nutrient content of the eroded material. Rainfall intensity was the only significant factor in determining post-fire erosion rates from individual storm events. Short duration, high intensity thunderstorms with a maximum 10-min rainfall intensity of 75 mm h,1 caused the highest erosion rates (greater than 20 t ha,1). Long duration, low intensity rains produced little erosion (less than 001 t ha,1). Total C and N in the collected sediment varied directly with the organic matter; because the collected sediment was mostly mineral soil, the C and N content was small. Minimal amounts of Mg, Ca, and K were detected in the eroded sediments. The mean annual erosion rate predicted by Disturbed WEPP (Water Erosion Prediction Project) was 15% less than the mean annual erosion rate measured, which is within the accuracy range of the model. Published in 2007 by John Wiley & Sons, Ltd. [source]

Likelihood of Illegal Alcohol Sales at Professional Sport Stadiums

ALCOHOLISM, Issue 11 2008
Traci L. Toomey
Background:, Several studies have assessed the propensity for illegal alcohol sales at licensed alcohol establishments and community festivals, but no previous studies examined the propensity for these sales at professional sport stadiums. In this study, we assessed the likelihood of alcohol sales to both underage youth and obviously intoxicated patrons at professional sports stadiums across the United States, and assessed the factors related to likelihood of both types of alcohol sales. Methods:, We conducted pseudo-underage (i.e., persons age 21 or older who appear under 21) and pseudo-intoxicated (i.e., persons feigning intoxication) alcohol purchase attempts at stadiums that house professional hockey, basketball, baseball, and football teams. We conducted the purchase attempts at 16 sport stadiums located in 5 states. We measured 2 outcome variables: pseudo-underage sale (yes, no) and pseudo-intoxicated sale (yes, no), and 3 types of independent variables: (1) seller characteristics, (2) purchase attempt characteristics, and (3) event characteristics. Following univariate and bivariate analyses, we a separate series of logistic generalized mixed regression models for each outcome variable. Results:, The overall sales rates to the pseudo-underage and pseudo-intoxicated buyers were 18% and 74%, respectively. In the multivariate logistic analyses, we found that the odds of a sale to a pseudo-underage buyer in the stands was 2.9 as large as the odds of a sale at the concession booths (30% vs. 13%; p = 0.01). The odds of a sale to an obviously intoxicated buyer in the stands was 2.9 as large as the odds of a sale at the concession booths (89% vs. 73%; p = 0.02). Conclusions:, Similar to studies assessing illegal alcohol sales at licensed alcohol establishments and community festivals, findings from this study shows the need for interventions specifically focused on illegal alcohol sales at professional sporting events. [source]

Reducing runoff by managing crop location at the catchment level, considering agronomic constraints at farm level

A. Joannon
Abstract Runoff and erosion cause frequent damage through muddy floods in the loess belt of Northern Europe. One possibility for reducing damage is to lower runoff on agricultural land by spatially alternating different crops at the catchment level. But crop location results from decisions taken at the farm level. This study aimed to assess the existing leeway to modify crop location in the farms of a catchment, in order to reduce runoff at the catchment's outlet. The case study was the Bourville catchment (1086,ha), cultivated by 28 farmers and located in Pays de Caux, France. First, crop location rules in the 14 main farms of the catchment were analysed on the basis of surveys carried out with farmers, distinguishing spatial constraints from temporal ones. These rules made it possible to simulate crop location on each farm territory for the 2001,2002 crop year. Each field of the catchment was classified depending on whether one or several crops could be sown, taking into account both field history and farmer decision rules. Then two extreme scenarios of crop location in the Bourville catchment were built. Runoff simulation at the outlet with the STREAM model showed that runoff could be reduced while sticking to current farmer decision rules in terms of crop location. Depending on rainfall event characteristics, runoff reduction varied between 135,per,cent and 45,per,cent. Copyright 2006 John Wiley & Sons, Ltd. [source]

Primitive immune systems: Are your ways my ways?

Baruch Rinkevich
Summary:, Although vertebrate immune systems have been commonly conceived as exquisitely developed to combat pervasiveness by pathogens, they are not infallible. The enigmatic expression of histocompatibility in vertebrates, the manifestation of natural chimerism, autoimmunity, malignancy, and other puzzling outcomes hint that immunity did not arise in evolution to fight infections and that this capacity is a late evolutionary appendage, owing its appearance to the redeployment of a system developed for other reasons. Allorecognition in the colonial tunicate Botryllus schlosseri serves here as a platform for a contending paradigm, advocating that immunity has developed as a surveillance machinery against and for purging of nascent selfish cells (stemmed from a kin organism or from transformed cells within the organism of origin). Defense against pathogens (always representing xenogeneic aliens) appeared later, revealing the multiplicity of newly developed phenomena. Allorecognition events characteristic of the Botryllus primitive immune system, such as fusion versus rejection, the morphological resorption with its expressed hierarchy, and the somatic/germ-cell parasitic outcomes, provide clues to the evolutionary basis of allorecognition. Recent work on Botryllus immunity that highlights the cost of littering individuality by somatic variants/allogeneic cells is discussed. [source]