Saint Louis University

About: Saint Louis University is a education organization based out in St Louis, Missouri, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 18927 authors who have published 34895 publications receiving 1267475 citations. The organization is also known as: SLU & St. Louis University.

Modified perpendicular drought index (MPDI): a real-time drought monitoring method

Abstract: Soil moisture and vegetation growth are the most direct and important indicators of drought events and, therefore, an understanding of vegetation and soil spectral behavior is critical to the drought estimation. Recently, Ghulam et al. [Ghulam, A., Qin, Q., Zhan, Z., 2006. Designing of the perpendicular drought index. Environmental Geology, doi:10.1007/s00254-006-0544-2 (accessed March 8, 2007).] established the Perpendicular Drought Index (PDI) that is based on an extensive analysis of spatial distribution features of soil moisture in NIR-Red spectral space. In this paper, an improved drought monitoring method, the Modified Perpendicular Drought Index (MPDI), is developed introducing vegetation fraction, which takes into account both soil moisture and vegetation growth. To validate the drought indices proposed by this paper, Enhanced Thematic Mapper Plus (ETM+) and MODerate Resolution Imaging Spectrometer (MODIS) images from different times registered over different eco-systems with various drought conditions are used to calculate the PDI and MPDI over ground measuring points. The PDI and MPDI are then compared to an in-situ drought index obtained from field measurements made synchronously with the satellite overpass, including the bulk soil moisture content at different soil depths, field moisture capacity, wilting coefficient, etc. It is evident from the results that the PDI and the MPDI is highly accordant with in-situ drought values with the highest correlation (R 2 = 0.8134) found between the MPDI and an in-situ drought index derived from 0-20 cm mean soil moisture. This study concludes that the PDI and the MPDI provide quite similar results for bare soil surfaces, especially in the early stages of vegetation growth. However, the MPDI demonstrates a much better performance in measuring vegetated surfaces since it takes into account both soil moisture and vegetation growth in the modeling process. The MPDI has the potential to provide a simple and real-time drought monitoring method in the remote estimation of drought phenomena. © 2007 International Society of Photogrammetry and Remote Sensing, Inc. (ISPRS).

Loss of lamin A function increases chromatin dynamics in the nuclear interior

Abstract: Chromatin is organized in a highly ordered yet dynamic manner in the cell nucleus, but the principles governing this organization remain unclear. Similarly, it is unknown whether, and how, various proteins regulate chromatin motion and as a result influence nuclear organization. Here by studying the dynamics of different genomic regions in the nucleus of live cells, we show that the genome has highly constrained dynamics. Interestingly, depletion of lamin A strikingly alters genome dynamics, inducing a dramatic transition from slow anomalous diffusion to fast and normal diffusion. In contrast, depletion of LAP2α, a protein that interacts with lamin A and chromatin, has no such effect on genome dynamics. We speculate that chromosomal inter-chain interactions formed by lamin A throughout the nucleus contribute to chromatin dynamics, and suggest that the molecular regulation of chromatin diffusion by lamin A in the nuclear interior is critical for the maintenance of genome organization.