Long-Term Soil Productivity Study: 25-Year Vegetation Response to Varying Degrees of Disturbance in Aspen-Dominated Forest Spanning the Upper Lake States

Installations of the Long-Term Soil Productivity Study were established in northern Minnesota and Michigan at the Chippewa, Ottawa, and Huron-Manistee National Forests (NFs) in the early 1990s and have since provided a wealth of data for assessing the response of aspen-dominated forest ecosystems to varying levels of organic matter removal and soil compaction. An assessment of 25-year standing woody biomass indicates that neither whole-tree harvest nor whole-tree harvest combined with forest floor removal reduced forest productivity on silt-loam soils compared with conventional, stem-only harvest; however, moderate and heavy compaction did negatively impact aspen biomass and stem densities. In contrast, whole-tree harvest reduced standing biomass of aspen and all species combined on sandy soils at the Huron NF while compaction had no discernable impact. Neither treatment factor affected vegetation response at the Ottawa NF (clay soils), but reduced sample size at this site may have increased variability. Over all, the response of standing biomass and forest structure to organic matter removal and compaction treatments demonstrate that the sustainability of practices such as whole-tree harvesting and associated potential for soil impacts varies with site conditions, even when stands are dominated by the same species (e.g., Populus tremuloides)

Proof of concept of a method that assesses the spread of microbial infections with spatially explicit and non-spatially explicit data

<p>Abstract</p> <p>Background</p> <p>A method that assesses bacterial spatial dissemination was explored. It measures microbial genotypes (defined by electrophoretic patterns or EP), host, location (farm), interfarm Euclidean distance, and time. Its proof of concept (construct and internal validity) was evaluated using a dataset that included 113 <it>Staphylococcus aureus </it>EPs from 1126 bovine milk isolates collected on 23 farms between 1988 and 2005.</p> <p>Results</p> <p>Construct validity was assessed by comparing results based on the interfarm Euclidean distance (a spatially explicit measure) and those produced by the (non-spatial) interfarm number of isolates reporting the same EP. The distance associated with EP spread correlated with the interfarm number of isolates/EP (<it>r </it>= .59, <it>P </it>< 0.02). Internal validity was estimated by comparing results obtained with different versions of the same indices. Concordance was observed between: (a) EP distance (estimated microbial dispersal over space) and EP speed (distance/year, <it>r </it>= .72, <it>P </it>< 0.01), and (b) the interfarm number of isolates/EP (when measured on the basis of non-repeated cow testing) and the same measure as expressed by repeated testing of the same animals (<it>r </it>= .87, <it>P </it>< 0.01). Three EPs (2.6% of all EPs) appeared to be super-spreaders: they were found in 26.75% of all isolates. Various indices differentiated local from spatially disseminated infections and, within the local type, infections suspected to be farm-related were distinguished from cow-related ones.</p> <p>Conclusion</p> <p>Findings supported both construct and internal validity. Because 3 EPs explained 12 times more isolates than expected and at least twice as many isolates as other EPs did, false negative results associated with the remaining EPs (those erroneously identified as lacking spatial dispersal when, in fact, they disseminated spatially), if they occurred, seemed to have negligible effects. Spatial analysis of laboratory data may support disease surveillance systems by generating hypotheses on microbial dispersal ability.</p

The Interior Dynamics of Water Planets

The ever-expanding catalog of detected super-Earths calls for theoretical studies of their properties in the case of a substantial water layer. This work considers such water planets with a range of masses and water mass fractions (2 to 5 M_Earth, 0.02% to 50% H2 O). First, we model the thermal and dynamical structure of the near-surface for icy and oceanic surfaces, finding separate regimes where the planet is expected to maintain a subsurface liquid ocean and where it is expected to exhibit ice tectonics. Newly discovered exoplanets may be placed into one of these regimes given estimates of surface temperature, heat flux, and gravity. Second, we construct a parameterized convection model for the underlying ice mantle of higher ice phases, finding that materials released from the silicate iron core should traverse the ice mantle on the timescale of 0.1 to 100 megayears. We present the dependence of the overturn times of the ice mantle and the planetary radius on total mass and water mass fraction. Finally, we discuss the implications of these internal processes on atmospheric observables.Comment: 9 page 4 figure

Dynamic masses for the close PG1159 binary SDSSJ212531.92-010745.9

SDSSJ212531.92-010745.9 is the first known PG1159 star in a close binary with a late main sequence companion allowing a dynamical mass determination. The system shows flux variations with a peak-to-peak amplitude of about 0.7 mag and a period of about 6.96h. In August 2007, 13 spectra of SDSSJ212531.92-010745.9 covering the full orbital phase range were taken at the TWIN 3.5m telescope at the Calar Alto Observatory (Alm\'{e}ria, Spain). These confirm the typical PG1159 features seen in the SDSS discovery spectrum, together with the Balmer series of hydrogen in emission (plus other emission lines), interpreted as signature of the companion's irradiated side. A radial velocity curve was obtained for both components. Using co-added radial-velocity-corrected spectra, the spectral analysis of the PG1159 star is being refined. The system's lightcurve, obtained during three seasons of photometry with the G\"ottingen 50cm and T\"ubingen 80cm telescopes, was fitted with both the NIGHTFALL and PHOEBE binary simulation programs. An accurate mass determination of the PG1159 component from the radial velocity measurements requires to first derive the inclination, which requires light curve modelling and yields further constraints on radii, effective temperature and separation of the system's components. From the analysis of all data available so far, we present the possible mass range for the PG1159 component of SDSSJ212531.92-010745.9.Comment: 8 pages, in "White dwarfs", proceedings of the 16th European White Dwarf Workshop, eds. E. Garcia-Berro, M. Hernanz, J. Isern, S. Torres, to be published in J. Phys.: Conf. Se

The Treatment-Naive Microbiome in New-Onset Crohn\u27s Disease

Inflammatory bowel diseases (IBDs), including Crohn\u27s disease (CD), are genetically linked to host pathways that implicate an underlying role for aberrant immune responses to intestinal microbiota. However, patterns of gut microbiome dysbiosis in IBD patients are inconsistent among published studies. Using samples from multiple gastrointestinal locations collected prior to treatment in new-onset cases, we studied the microbiome in the largest pediatric CD cohort to date. An axis defined by an increased abundance in bacteria which include Enterobacteriaceae, Pasteurellacaea, Veillonellaceae, and Fusobacteriaceae, and decreased abundance in Erysipelotrichales, Bacteroidales, and Clostridiales, correlates strongly with disease status. Microbiome comparison between CD patients with and without antibiotic exposure indicates that antibiotic use amplifies the microbial dysbiosis associated with CD. Comparing the microbial signatures between the ileum, the rectum, and fecal samples indicates that at this early stage of disease, assessing the rectal mucosal-associated microbiome offers unique potential for convenient and early diagnosis of CD

Structural characterization of angiotensin I-converting enzyme in complex with a selenium analogue of captopril

Human somatic angiotensin I-converting enzyme (ACE), a zinc-dependent dipeptidyl carboxypeptidase, is central to the regulation of the renin–angiotensin aldosterone system. It is a well-known target for combating hypertension and related cardiovascular diseases. In a recent study by Bhuyan and Mugesh [Org. Biomol. Chem. (2011) 9, 1356–1365], it was shown that the selenium analogues of captopril (a well-known clinical inhibitor of ACE) not only inhibit ACE, but also protect against peroxynitrite-mediated nitration of peptides and proteins. Here, we report the crystal structures of human testis ACE (tACE) and a homologue of ACE, known as AnCE, from Drosophila melanogaster in complex with the most promising selenium analogue of captopril (SeCap) determined at 2.4 and 2.35 Å resolution, respectively. The inhibitor binds at the active site of tACE and AnCE in an analogous fashion to that observed for captopril and provide the first examples of a protein–selenolate interaction. These new structures of tACE–SeCap and AnCE–SeCap inhibitor complexes presented here provide important information for further exploration of zinc coordinating selenium-based ACE inhibitor pharmacophores with significant antioxidant activity

A Model for the Information Content of Earnings Announcements

28 pages, 1 article*A Model for the Information Content of Earnings Announcements* (Schwager, Steven J.; Richardson, Gordon D.) 28 page

Application of Pulsed Field Gel Electrophoresis to Determine γ-ray-induced Double-strand Breaks in Yeast Chromosomal Molecules

The frequency of DNA double-strand breaks (dsb) was determined in yeast cells exposed to γ-rays under anoxic conditions. Genomic DNA of treated cells was separated by pulsed field gel electrophoresis, and two different approaches for the evaluation of the gels were employed: (1) The DNA mass distribution profile obtained by electrophoresis was compared to computed profiles, and the number of DSB per unit length was then derived in terms of a fitting procedure; (2) hybridization of selected chromosomes was performed, and a comparison of the hybridization signals in treated and untreated samples was then used to derive the frequency of dsb