University of Georgia

About: University of Georgia is a education organization based out in Athens, Georgia, United States. It is known for research contribution in the topics: Population & Gene. The organization has 41934 authors who have published 93622 publications receiving 3713212 citations. The organization is also known as: UGA & Franklin College.

Perceived Discrimination and the Adjustment of African American Youths: A Five-Year Longitudinal Analysis With Contextual Moderation Effects

Abstract: Longitudinal links between perceived racial discrimination and later conduct problems and depressive symptoms were examined among 714 African American adolescents who were 10-12 years old at recruitment. Data were gathered 3 times over a 5-year period. Hypotheses were tested via latent curve modeling and multiple-group latent growth modeling. Increases in perceived discrimination were associated with increased conduct problems and depressive symptoms. This association was weaker when youths received nurturant-involved parenting, affiliated with prosocial friends, and performed well academically. For conduct problems, the association was stronger for boys than for girls; for depressive symptoms, no gender differences emerged. The findings thus identify contextual variables that moderate the contribution of perceived discrimination to African American youths' adjustment.

Critical behavior of the three-dimensional Ising model: A high-resolution Monte Carlo study.

Abstract: Using recently developed histogram techniques and an ultrafast multispin coding simulation algorithm, we have investigated the critical behavior of the d=3 simple-cubic Ising model We have studied lattice sizes ranging from L=8 to 96 using between 3\ifmmode\times\else\texttimes\fi{}${10}^{6}$ and 12\ifmmode\times\else\texttimes\fi{}${10}^{6}$ Monte Carlo steps (complete lattice updates) By accurately measuring the finite-size behavior of several different thermodynamic quantities, we are able to determine the critical properties with a precision comparable to that obtained with Monte Carlo renormalization-group and sophisticated series-expansion techniques The best estimate of the inverse critical temperature from our analysis is ${\mathit{K}}_{\mathit{c}}$=0221 659 5\ifmmode\pm\else\textpm\fi{}0000 002 6 The advantages of the histogram technique are discussed, as are the potential problems that can arise at this level of resolution

Mutation of a Chitinase-Like Gene Causes Ectopic Deposition of Lignin, Aberrant Cell Shapes, and Overproduction of Ethylene

Abstract: Chitinase-like proteins have long been proposed to play roles in normal plant growth and development, but no mutations in chitinase-like genes have been obtained previously to support this hypothesis. In this study, we have shown that the gene responsible for the elp1 mutation in Arabidopsis encodes a chitinase-like protein (AtCTL1). Mutation of this chitinase-like gene caused ectopic deposition of lignin and aberrant shapes of cells with incomplete cell walls in the pith of inflorescence stems. The AtCTL1 gene was expressed in all organs during normal plant growth and development, but it was not induced by wounding, salicylic acid, pectin fragments, or ethylene. Consistent with its ubiquitous expression pattern, mutation of the AtCTL1 gene affected many aspects of plant growth and development, including exaggerated hook curvature, reduced length and increased diameter of hypocotyls in dark-grown seedlings, and reduced root length and increased number of root hairs in light-grown seedlings. The mutant phenotypes could be rescued partially by ethylene inhibitors, and ethylene production in the mutant was significantly greater than in the wild type. Together, these results suggest that AtCTL1, a chitinase-like gene, is essential for normal plant growth and development in Arabidopsis.

Aggregate-Protected and Unprotected Organic Matter Pools in Conventional- and No-Tillage Soils

Abstract: No-tillage (NT) practices can result in greater soil aggregation and higher soil organic matter (SOM) levels than conventional-tillage (CT) practices, but the mechanisms for these effects are poorly known. Our objectives were to describe the size and quality of biologically active pools of aggregate-associated SOM in long-term CT and NT soils of the southeastern USA. Samples were collected from replicated CT and NT plots on a Hiwassee sandy clay loam (clayey, kaolinitic, thermic Rhodic Kanhapludult) and separated into four aggregate size classes (>2000, 250-2000, 106-250, 53-106 m) by wet sieving. Potentially mineralizable C and N and N2O emissions were measured from 20-d laboratory incubations of intact and crushed macroaggregates (>250 m) and intact microaggregates (<250 m). Three primary pools of aggregate-associated SOM were quantified: unprotected, protected, and resistant C and N. Aggregate-unprotected pools of SOM were 21 to 65% higher in surface soils of NT than of CT, with greater differences in the macroaggregate size classes. Disruption of macroaggregates increased the mineralization of SOM in NT but had little effect in CT. Rates of mineralization from protected and unprotected pools of C were higher in surface soils of CT than of NT. Macroaggregateprotected SOM accounted for 18.8 and 19.1% of the total mineralizable C and N (0-15 cm), respectively, in NT but only 10.2 and 5.4% of the total mineralizable C and N in CT. Our results indicate that macroaggregates in NT soils provide an important mechanism for the protection of SOM that may otherwise be mineralized under CT practices.