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.

Biological evidence supports an early and complex emergence of the Isthmus of Panama

Abstract: The linking of North and South America by the Isthmus of Panama had major impacts on global climate, oceanic and atmospheric currents, and biodiversity, yet the timing of this critical event remains contentious. The Isthmus is traditionally understood to have fully closed by ca. 3.5 million years ago (Ma), and this date has been used as a benchmark for oceanographic, climatic, and evolutionary research, but recent evidence suggests a more complex geological formation. Here, we analyze both molecular and fossil data to evaluate the tempo of biotic exchange across the Americas in light of geological evidence. We demonstrate significant waves of dispersal of terrestrial organisms at approximately ca. 20 and 6 Ma and corresponding events separating marine organisms in the Atlantic and Pacific oceans at ca. 23 and 7 Ma. The direction of dispersal and their rates were symmetrical until the last ca. 6 Ma, when northern migration of South American lineages increased significantly. Variability among taxa in their timing of dispersal or vicariance across the Isthmus is not explained by the ecological factors tested in these analyses, including biome type, dispersal ability, and elevation preference. Migration was therefore not generally regulated by intrinsic traits but more likely reflects the presence of emergent terrain several millions of years earlier than commonly assumed. These results indicate that the dramatic biotic turnover associated with the Great American Biotic Interchange was a long and complex process that began as early as the Oligocene–Miocene transition.

Mars-like soils in the Atacama Desert, Chile, and the dry limit of microbial life

Abstract: The Viking missions showed the martian soil to be lifeless and depleted in organic material and indicated the presence of one or more reactive oxidants. Here we report the presence of Mars-like soils in the extreme arid region of the Atacama Desert. Samples from this region had organic species only at trace levels and extremely low levels of culturable bacteria. Two samples from the extreme arid region were tested for DNA and none was recovered. Incubation experiments, patterned after the Viking labeled-release experiment but with separate biological and nonbiological isomers, show active decomposition of organic species in these soils by nonbiological processes.

Nonlinear Process Control

Abstract: The need for nonlinear process control systems introduction to nonlinear systems topics in nonlinear system theory identification techniques for nonlinear systems feedback linearization techniques nonlinear model control strategies design of nonlinear state observers artificial neural networks.

Expansion of a novel CAG trinucleotide repeat in the 5' region of PPP2R2B is associated with SCA12.

Abstract: The genetic aetiologies of at least 20% of autosomal dominant spinocerebellar ataxias (SCAs) have yet to be elucidated1 We have recently identified a novel form of autosomal dominant SCA, termed SCA12, in a large pedigree ('R') of German descent The phenotype is variable, but the prototypical phenotype is that of a classic spinocerebellar ataxia, and the disease resembles the spinocerebellar ataxias more closely than any other form of neurodegenerative disorder Age of onset ranges from 8 to 55 years Most individuals present in the fourth decade with upper extremity tremor, progressing over several decades to include head tremor, gait ataxia, dysmetria, dysdiadokinesis, hyperreflexia, paucity of movement, abnormal eye movements and, in the oldest subjects, dementia MRI or CT scans of five cases indicate both cortical and cerebellar atrophy

Sex, race/ethnicity, socioeconomic status, and BMI in relation to self-perception of overweight

Abstract: Objective: To compare the self-perception of overweight in the study population according to sex, race/ethnicity, and socioeconomic status and to compare the self-perception of overweight among individuals classified as normal weight, overweight, and obese. Research Methods and Procedures: Data from 5440 adults who participated in the 1994 to 1996 Continuing Survey of Food Intakes by Individuals and the Diet and Health Knowledge Survey conducted by the U.S. Department of Agriculture were analyzed. Data for analysis included self-perceived weight status, self-reported weight and height, and demographic and socioeconomic data. Underweight individuals, defined as those with a body mass index <18.5 kg/m2, were excluded from the analysis. Results: Self-perception of overweight was more common in women compared with men and in whites compared with blacks or Hispanics. Both the correct and incorrect perception of overweight was more common in normal weight and overweight white women compared with black women. More overweight and obese white men correctly perceived their overweight status compared with black men. Multiple logistic regression showed that the odds ratio of perceived overweight was significantly higher in women, whites, and individuals with higher body mass index, higher income, and higher education. Discussion: Self-perceived overweight varied by sex, race/ethnicity, and socioeconomic status. Erroneous perception of body weight may have important health and behavioral implications. In particular, a considerable proportion of overweight men may be at risk of obesity if they continue to perceive themselves as having normal weight.