Louisiana State University

About: Louisiana State University is a education organization based out in Baton Rouge, Louisiana, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 40206 authors who have published 76587 publications receiving 2566076 citations. The organization is also known as: LSU & Louisiana State University and Agricultural and Mechanical College.

Using Qualitative Comparative Analysis in Strategic Management Research An Examination of Combinations of Industry, Corporate, and Business-Unit Effects

Abstract: The authors present qualitative comparative analysis (QCA) as a viable method for strategic management research. Specifically, they demonstrate its ability to examine the potential interdependence ...

Treefall gap size effects on above‐ and below‐ground processes in a tropical wet forest

Abstract: 1 We examined the effects of variation in gap size on above- and below-ground light and nutrient processes in a tropical wet forest in Costa Rica. 2 Trees were felled to create canopy openings ranging in size from 65 to 611 m2. Following treefall, we measured initial litter mass in the crown zone of six gaps. During the subsequent year, we measured litter decomposition rate and light levels as well as NH4-N, NO3-N and PO4-P levels in surface soils, soil moisture and fine root mass. We also measured growth rates of fertilized and non-fertilized plants of four species of Miconia (Melastomataceae) to assess nutrient limitation to plant growth in large gaps. 3 Light levels in the centres of gaps were significantly related to size of the canopy opening. After 1 year, light levels near the ground in larger openings (35–40% full sunlight immediately after treefall) declined to levels similar to those in smaller gaps (10–20%). 4 Although canopy opening had only slight effects on soil NH4-N, NO3-N pools were significantly greater in gaps than in understorey at both sites. The effect was positively correlated with gap size. Extractable PO4-P was also greater in gaps than in adjacent understorey, although the difference did not vary as a function of gap size. In three of six gaps, fine root biomass was less in gaps than in adjacent understorey. 5 Of four species of Miconia, only M. affinis, a small tree common in early secondary forests, grew significantly faster in fertilized than in non-fertilized treatments in three large gaps. 6 Our data suggest that higher nutrient pools in surface soils of treefall gaps may result from decomposition and mineralization of the large mass of fresh litter from the fallen tree. While growth rates of shade-tolerant rain forest trees and shrubs are not much affected by the increased nutrient availability even at high light levels, growth rates of pioneer or high-light demanding species may be enhanced by increased above- and below-ground resources.

Exposure to electronic cigarettes impairs pulmonary anti-bacterial and anti-viral defenses in a mouse model

Abstract: Electronic cigarettes (E-cigs) have experienced sharp increases in popularity over the past five years due to many factors, including aggressive marketing, increased restrictions on conventional cigarettes, and a perception that E-cigs are healthy alternatives to cigarettes. Despite this perception, studies on health effects in humans are extremely limited and in vivo animal models have not been generated. Presently, we determined that E-cig vapor contains 7x1011 free radicals per puff. To determine whether E-cig exposure impacts pulmonary responses in mice, we developed an inhalation chamber for E-cig exposure. Mice that were exposed to E-cig vapor contained serum cotinine concentrations that are comparable to human E-cig users. E-cig exposure for 2 weeks produced a significant increase in oxidative stress and moderate macrophage-mediated inflammation. Since, COPD patients are susceptible to bacterial and viral infections, we tested effects of E-cigs on immune response. Mice that were exposed to E-cig vapor showed significantly impaired pulmonary bacterial clearance, compared to air-exposed mice, following an intranasal infection with Streptococcus pneumonia. This defective bacterial clearance was partially due to reduced phagocytosis by alveolar macrophages from E-cig exposed mice. In response to Influenza A virus infection, E-cig exposed mice displayed increased lung viral titers and enhanced virus-induced illness and mortality. In summary, this study reports a murine model of E-cig exposure and demonstrates that E-cig exposure elicits impaired pulmonary anti-microbial defenses. Hence, E-cig exposure as an alternative to cigarette smoking must be rigorously tested in users for their effects on immune response and susceptibility to bacterial and viral infections.