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.

Edaphic variation and the mesoscale distribution of tree species in a neotropical rain forest

Abstract: 1 Do local edaphic factors over short environmental gradients affect the distribution and abundance of tree species in tropical rain forests? We addressed this question by examining the responses of tree species to soil type, topographic position and slope angle in an upland old-growth tropical rain forest landscape in Costa Rica, Central America. 2 The study area covered 216 ha of non-swamp old growth and included replicated landscape units such as ridgetop to swale catenas, small watersheds, and alluvial terraces. An existing soils map was refined using additional sampling along a regularly spaced grid. Three soil units were defined: residual soils derived from in-place weathering of basaltic parent material; old alluvial terrace soils formed by precontemporary flooding; and soils of stream valleys. A Geographic Information System was used to assign soil type to 2190 post-establishment individuals of nine tree species in a long-term demographic study. Topographic position and slope angle were measured in the field. 3 Data from 433 regularly spaced sample points were used to generate an expected distribution of edaphic variables, which was compared with the number of individuals of each species in each edaphic category. 4 Non-random distributions among soil types were found for seven of the nine species, with topographic positions for six species, and with slope angle classes for four species. 5 The issue of what constitutes an independent sample of establishment was analysed by considering the old-growth character of the landscape and evidence for frequent dispersal among edaphic units. A re-analysis of species’ distributions using only individuals > 4 cm diameter showed that results from the original analyses were robust. 6 Soil type (residual vs. old alluvial) was not significantly related to diameter growth. Three species showed significant differences in size class distributions between soil types with increasing diameter. 7 Tree species in tropical rain forests are frequently non-randomly distributed along relatively short edaphic gradients on upland soils. Future studies should increase the number of species and spatial scale analysed, incorporate better analyses of edaphic variables, and include experiments to identify the ecological processes that generate these non-random distributions.

Segmentation of a High Resolution Urban Scene Using Texture Operators.

Abstract: A study aimed at segmenting a high-resolution black and white image of Sunnyvale, California, is described. In this study regions were classified as belonging to any one of nine classes: residential, commercial/industrial, mobile home, water, dry land, runway/taxiway, aircraft parking, multilane highway, and vehicle parking. The classes were selected so that they directly relate to the Defense Mapping Agency's Mapping, Charting and Geodesy tangible features. To attack the problem a statistical segmentation procedure was devised. The primitive operators used to drive the segmentation are texture measures derived from cooccurrence matrices. The segmentation procedure considers three kinds of regions at each level of the segmentation: uniform, boundary, and unspecified. At every level the procedure differentiates uniform regions from boundary and unspecified regions. In the assigns a class label to the uniform regions. The boundary and unspecified regions are split to form higher level regions. The methodologies involved are mathematically developed as a series of hypothesis tests. While only a one-level segmentation was performed studies are described which show the capabilities of each of these hypothesis tests. In particular an 83% correct classification was obtained in testing the labeling procedure. These studies indicate that the proposed procedure should be useful for land use classifications as well as other problems.

Adenosine cyclic 3',5'-monophosphate dependent protein kinase: kinetic mechanism for the bovine skeletal muscle catalytic subunit.

Abstract: The kinetic mechanism for adenosine cyclic 3',5'-monophosphate dependent protein kinase was determined from initial velocity studies in the absence and presence of the product MgADP and dead-end inhibitors. Data are consistent with random addition of MgATP and Ser-peptide and ordered release of phospho-Ser-peptide and MgADP with a dead-end E-MgADP-Ser-peptide complex. In addition to the metal required for the nucleotide, we also characterized the binding of Mg2+ to a second site. Increasing the Mg2+ results in a 5-6-fold decrease in V,,, in the presence or absence of 0.1 M KCl. There is a 5-fold increase in V/KMgATP in the absence of KCl and a 13-fold increase in V/KMdTP at 0.1 M KC1. The effect of increasing free Mg2+ on V,,, and V/K was also obtained with MgITP (20% the V,,, with MgATP) and MgGTP (10% the V,,, with MgATP) as substrates. The dissociation constant for Mg2+ from E-Ser-peptide-Mg2+ and central complexes is 2-3 mM. At low concentrations of free Adenosine cyclic 3',5'-monophosphate dependent protein kinase catalyzes the phorphorylation of a variety of proteins according to