RNA polymerase V-dependent small RNAs in Arabidopsis originate from small, intergenic loci including most SINE repeats.

In plants, heterochromatin is maintained by a small RNA-based gene silencing mechanism known as RNA-directed DNA methylation (RdDM). RdDM requires the non-redundant functions of two plant-specific DNA-dependent RNA polymerases (RNAP), RNAP IV and RNAP V. RNAP IV plays a major role in siRNA biogenesis, while RNAP V may recruit DNA methylation machinery to target endogenous loci for silencing. Although small RNA-generating regions that are dependent on both RNAP IV and RNAP V have been identified previously, the genomic loci targeted by RNAP V for siRNA accumulation and silencing have not been described extensively. To characterize the RNAP V-dependent, heterochromatic siRNA-generating regions in the Arabidopsis genome, we deeply sequenced the small RNA populations of wild-type and RNAP V null mutant (nrpe1) plants. Our results showed that RNAP V-dependent siRNA-generating loci are associated predominately with short repetitive sequences in intergenic regions. Suppression of small RNA production from short repetitive sequences was also prominent in RdDM mutants including dms4, drd1, dms3 and rdm1, reflecting the known association of these RdDM effectors with RNAP V. The genomic regions targeted by RNAP V were small, with an estimated average length of 238 bp. Our results suggest that RNAP V affects siRNA production from genomic loci with features dissimilar to known RNAP IV-dependent loci. RNAP V, along with RNAP IV and DRM1/2, may target and silence a set of small, intergenic transposable elements located in dispersed genomic regions for silencing. Silencing at these loci may be actively reinforced by RdDM

Stress and coping in mothers of children with developmental disabilities across the lifespan.

Maternal stress associated with providing care at home for a son/daughter with a developmental disability was investigated using a cross-sectional design. Respondents included 186 mothers whose offspring ranged in age from 5 to 53 years. New measures were created to assess the contribution of stressors, resources, and the perception of stressors to the prediction of stress. Resources and perception were evaluated to determine if they had a moderating effect on stress. A negative relationship was found between maternal stress and age of the son/daughter with the developmental disability and between maternal stress and age of the mother. The statistical significance of the stressors, resources, and perceptions in predicting stress varied across the son/daughter\u27s age and the mother\u27s age. When collapsing across age, stressors and perceptions were found to be the best predictors of maternal stress. Perception of the stressor was found to have a moderating effect on stress only if there was a high number of stressors present in the family environment. Implications of these findings and suggestions for future research are discussed.Dept. of Psychology. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1997 .L5. Source: Masters Abstracts International, Volume: 37-01, page: 0367. Adviser: Robert Orr. Thesis (M.A.)--University of Windsor (Canada), 1997

Direct acoustic profiling of DNA hybridisation using HSV type 1 viral sequences

We describe the detection of specific, conserved DNA sequences of herpes simplex virus (HSV) type 1 by means of a novel, high sensitivity acoustic biosensor. Repeated assays on planar and polymeric carboxylic acid- and biotin-presenting surface chemistries enabled statistical comparison of assay specificity and sensitivity and evaluation of assay Z-factor scores. Using a three minute hybridisation with NeutrAvidin capture for signal enhancement, it was possible to detect HSV viral nucleic acids at 5.2 6 10211 M concentration. c The Royal Society of Chemistry 200

Evaluation of a Flux Chamber for Assessing Gaseous Emissions and Treatment Effects of Poultry Manure

The need to quantify air emissions from animal feeding operations (AFOs) with relative ease and reasonable certainty continues to rise. Exploration of practical means to reduce air emissions also calls for less sophisticated but reasonably dependable methods to quantify the treatment effect. Although mobile air emissions monitoring units (MAEMUs) capable of precise and real-time emission measurement is the norm for continuous, intensive monitoring of emissions from mechanically ventilated animal facilities, their relative immobility and high cost are limiting the widespread use. Several other methods, such as gas-washing, micro-meteorological, wind tunnel, flux chamber, and mass-balance methods, have been employed to accommodate different measurement needs. Flux chambers have the advantages of being portable, small size, low cost, and less labor requirement. The objectives of this study were: (1) to develop a portable emission flux chamber system (EFC) for in-situ measurement of ammonia (NH3) and carbon dioxide (CO2) emissions from manure; (2) to assess gaseous (NH3 and CO2) emissions of high-rise layer houses with the EFC vs. MAEMU; and (3) to evaluate the adequacy of using the EFC to determine the effects of dietary regimens on ammonia emissions from the layer manure. The preliminary data showed that NH3 emission from the manure surface measured with the EFC was 8% to 16% that of the whole barn measured with the MAEMU, while CO2 emission from the manure surface was 1% to 4% of the barn emission. The preliminary results obtained with EFC concerning the dietary efficacy of ammonia emission reduction were mixed as compared to those obtained with the MAEMU. More evaluation is continuing

Asymmetric tidal mixing due to the horizontal density gradient

Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 418-434, doi:10.1175/2007JPO3372.1.Stratification and turbulent mixing exhibit a flood–ebb tidal asymmetry in estuaries and continental shelf regions affected by horizontal density gradients. The authors use a large-eddy simulation (LES) model to investigate the penetration of a tidally driven bottom boundary layer into stratified water in the presence of a horizontal density gradient. Turbulence in the bottom boundary layer is driven by bottom stress during flood tides, with low-gradient (Ri) and flux (Rf) Richardson numbers, but by localized shear during ebb tides, with Ri = ¼ and Rf = 0.2 in the upper half of the boundary layer. If the water column is unstratified initially, the LES model reproduces periodic stratification associated with tidal straining. The model results show that the energetics criterion based on the competition between tidal straining and tidal stirring provides a good prediction for the onset of periodic stratification, but the tidally averaged horizontal Richardson number Rix has a threshold value of about 0.2, which is lower than the 3 suggested in a recent study. Although the tidal straining leads to negative buoyancy flux on flood tides, the authors find that for typical values of the horizontal density gradient and tidal currents in estuaries and shelf regions, buoyancy production is much smaller than shear production in generating turbulent kinetic energy.This work is supported by Grants OCE-0451699 and OCE-0451740 from the National Science Foundation

Partially decoupling and collar bonding of the encapsulated rebar rockbolts to improve their performance in seismic prone deep underground excavations

© 2018 Rockbolt is widely employed all over the world as an effective ground reinforcement element in order to secure the underground workplaces. Ordinary encapsulated rebar or rebar rockbolt is most popular and commonly used as reinforcement in a ground support system because of its accessibility, cost effectiveness and easy practicability. Reinforcement elements in a seismic condition such as rock burst have to dissipate the energy release of the dynamic impact via their deformation and ultimate load capacity, knowing that the former is more important. In other words, achieving early stiff behaviour along with large deformation capacity in rockbolts are the goals for new development in rock reinforcement. Yielding rockbolts are expensive while some of them have large deformation capability with low ultimate load capacity. In this paper, modifications were made on encapsulation of rebar rockbolts to utilise it effectively as a yielding reinforcement in seismic conditions. Applying a sufficient decoupled length in the shank of rebar rockbolts which industry has regularly been using to control the bulking of the stress fractured ground, improves the deformation capacity of the bolt. Additionally, leaving a collar bonding underneath of the bearing pad and plate removes the weaknesses of the head anchorage of rockbolt. Therefore the dynamic performance of the bolt is improved by these easily applicable modifications. The behaviour and performance of encapsulated rockbolts have been discussed first, then the effects of modifications are illustrated. The proposed modification of the rebars is not only cost effective but also easy to apply in the field and improves the performance of reinforcements in seismic prone zones

Effects of Dietary Modification on Laying Hens in High-Rise Houses: Part I – Emissions of Ammonia, Hydrogen Sulfide and Carbon Dioxide

Dietary manipulation can substantially lower ammonia (NH3) emissions from laying-hen houses or manure storage. Recent lab studies showed a reduction of 40–60% in ammonia emissions for an experimental (EcoCalTM) diet as compared the standard or control diet. However, adoption of a mitigation technology at commercial production level should be preceded by substantial field verification tests to document not only NH3 emission reduction, but also impact of the strategy on production performance of the hens and cash returns. A study to assess the effects of feeding diets containing EcoCal on NH3, hydrogen sulfide (H2S), and carbon dioxide (CO2) emissions, laying-hen production performance, and economic returns was conducted at a commercial laying-hen farm in central Iowa. Two houses (256,000 or 262,000 hens per house) were used for the study. Hens in one house were fed the EcoCal diet while hens in the other house were fed a standard or control diet containing no EcoCal. A state-of-the-art mobile air emissions monitoring unit (MAEMU) and the associated sampling system were used to continuously monitor the gaseous concentrations, ventilation rate and environmental conditions. Comparative data collected from December 2006 to May 2007 are presented in this paper. Data from this period showed that the EcoCal diet led to NH3 emission reduction by up to 23.2% (0.86±0.04 and 1.12±0.03 g/d·hen for EcoCal and Control diet, respectively), at the same time, H2S emission increased by up to 134% (4.38±0.20 and 1.82±0.07 mg/d·hen for EcoCal and Control diet, respectively), although the magnitude of H2S emission is rather small for both dietary regimens. Data on the hen production performance are reported in a companion paper (Roberts et al., 2008)