Predicting First-Year Student Success in Learning Communities: The Power of Pre-College Variables

The study used pre-college variables in the prediction of retention and probation status of first-year students in learning communities at a regional public university in South Texas. The correlational study employed multivariate analyses on data collected from the campus registrar about three consecutive cohorts (N = 4,215) of first-year students. Logistic regression models were developed to predict retention and probation status without respect to learning community membership, as well as for each learning community category. The logistic regression model to predict retention regardless of learning community membership included five pre-college variables, while the model to predict probation status included eight pre-college variables, five of which overlapped with the retention model. The models for each learning community contained different sets of predictor variables; the most common pre-college predictors were high school percentile and the number of days since orientation. The results of the study provide practical implications for the learning communities program, as well as learning community scholars interested in targeting interventions to the students who need them most

Evaluation of Murray's law in Psilotum nudum (Psilotaceae), an analogue of ancestral vascular plants

Journal ArticlePrevious work has shown that the xylem of seed plants follows Murray's law when conduits do not provide structural support to the plant. Here, compliance with Murray's law was tested in the stem photosynthesizer Psilotum nudum, a seedless vascular plant. Psilotum nudum was chosen because the central stele does not provide structural support, which means that Murray's law is applicable, and because its simple shoot structure resembles the earliest vascular plants

Correlated evolution of androgen receptor and aromatase revisited

Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of Oxford University Press for personal use, not for redistribution. The definitive version was published in Molecular Biology and Evolution 27 (2010): 2211-2215, doi:10.1093/molbev/msq129.Conserved interactions among proteins or other molecules can provide strong evidence for coevolution across their evolutionary history. Diverse phylogenetic methods have been applied to identify potential coevolutionary relationships. In most cases, these methods minimally require comparisons of orthologous sequences and appropriate controls to separate effects of selection from the overall evolutionary relationships. In vertebrates, androgen receptor (AR) and cytochrome p450 aromatase (CYP19) share an affinity for androgenic steroids, which serve as receptor ligands and enzyme substrates. In a recent study, Tiwary and Li (2009) reported that AR and CYP19 displayed a signature of ancient and conserved interactions throughout all of the Eumetazoa (i.e., cnidarians, protostomes, and deuterostomes). Because these findings conflicted with a number of previous studies, we reanalyzed the data set used by Tiwary and Li. First, our analyses demonstrate that the invertebrate genes used in the previous analysis are not orthologous sequences, but instead represent a diverse set of nuclear receptors and cytochrome p450 enzymes with no confirmed or hypothesized relationships with androgens. Second, we show that (1) their analytical approach, which measures correlations in evolutionary distances between proteins, potentially led to spurious significant relationships due simply to conserved domains and (2) control comparisons provide positive evidence for a strong influence of evolutionary history. We discuss how corrections to this method and analysis of key taxa (e.g., duplications in the teleost fish and suiform lineages) can inform investigations of the coevolutionary relationships between androgen receptor and aromatase.AMR was supported by the Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by The Beacon Institute for Rivers and Estuaries, and AMT was supported by WHOI Assistant Scientist Endowed Support

Development of a Semi-Automated Tobacco Stripping Machine Utilizing String Trimmers

Conventional stripping of burley tobacco is labor intensive and typically requires 50 to 75 worker hours per acre (wkr•h/acre). The goal of the project was to reduce labor by optimizing leaf removal by string trimmer heads using combinations of strings lengths and motor speeds. In tests conducted on a single grade, all leaves outside the grade were removed by hand. Plants were run through the machine for string lengths of 13, 18, and 23 cm (5, 7, and 9 in.) and associated motor speeds which were monitored and recorded. Stripping efficiencies were calculated for each plant and collectively for each set of four plants. The machine was then tested for three grade stripping efficiency. Particle size analysis tests were run to determine potential losses due to leaf shredding. Efficiencies for single grade testing ranged from 93% to 96% for optimal string length and speed combinations. Stripping three grades by machine resulted in an average of 97% efficiency. Potential losses due to shredding accounted for 5.6% of the total weight mechanically removed. It is believed that this stripping concept, implemented on a full scale four grade basis, could result in savings of at least 45 wkr•h/ha (18 wkr•h/acre)

Chromodomain Helicase DNA-Binding Proteins in Stem Cells and Human Developmental Diseases

Dynamic regulation of gene expression is vital for proper cellular development and maintenance of differentiated states. Over the past 20 years, chromatin remodeling and epigenetic modifications of histones have emerged as key controllers of rapid reversible changes in gene expression. Mutations in genes encoding enzymes that modify chromatin have also been identified in a variety of human neurodevelopmental disorders, ranging from isolated intellectual disability and autism spectrum disorder to multiple congenital anomaly conditions that affect major organ systems and cause severe morbidity and mortality. In this study, we review recent evidence that chromodomain helicase DNA-binding (CHD) proteins regulate stem cell proliferation, fate, and differentiation in a wide variety of tissues and organs. We also highlight known roles of CHD proteins in human developmental diseases and present current unanswered questions about the pleiotropic effects of CHD protein complexes, their genetic targets, nucleosome sliding functions, and enzymatic effects in cells and tissues.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140206/1/scd.2014.0544.pd

Ligand Decomposition during Nanoparticle Synthesis: Influence of Ligand Structure and Precursor Selection

Aliphatic amine and carboxylic acid ligands are widely used as organic solvents during the bottom-up synthesis of inorganic nanoparticles (NPs). Although the ligands’ ability to alter final NP properties has been widely studied, side reactivity of these ligands is emerging as an important mechanism to consider. In this work, we study the thermal decomposition of common ligands with varying functional groups (amines and carboxylic acids) and bond saturations (from saturated to polyunsaturated). Here, we investigate how these ligand properties influence decomposition in the absence and presence of precursors used in NP synthesis. We show that during the synthesis of inorganic chalcogenide NPs (Cu2ZnSnS4, CuxS, and SnSx) with metal acetylacetonate precursors and elemental sulfur, the ligand pyrolyzes, producing alkylated graphitic species. Additionally, there was less to no ligand decomposition observed during the sulfur-free synthesis of ZnO and CuO with metal acetylacetonate precursors. These results will help guide ligand selection for NP syntheses and improve reaction purity, an important factor in many applications.journal articl

Irritable bowel syndrome

This issue of eMedRef provides information to clinicians on the pathophysiology, diagnosis, and therapeutics of irritable bowel syndrome