9,447 research outputs found
Stream Water Quality to Support HUC 12 Prioritization in the Lake Wister Watershed, Oklahoma: August 2017 through May 2019
Nonpoint source pollution associated with human land use (agriculture and urbanization) is one of the leading causes of impairment to waterways in the United States (EPA 2000). The primary pollutants associated with agricultural and urban land use are sediment and nutrients which enter nearby streams during rain events and are then carried downstream. These sediments and nutrients may result in water quality issues in the downstream water bodies like increased algal growth or decreased water clarity (e.g. Smith et al., 1999). Best management practices (BMPs) are often used to mitigate the effects of nonpoint source pollution in the watershed. Practices such as riparian buffers installed along the edge of field and conservation tillage (e.g., no-till, spring-till, and cover crops) slow overland flow, reducing erosion and nutrient loss from the landscape (Schoumans et al. 2014). Installing BMPs throughout the entire watershed would have the greatest effect at reducing nonpoint source pollution; however, this is not socially or economically feasible. Targeting critical source areas or priority watersheds for BMPs installation, optimizes the benefits while reducing the overall (Sharpley et al. 2000)
Watershed Investigative Support to the Poteau Valley Improvement Authority: Stream Water Quality to Support HUC 12 Prioritization in the Lake Wister Watershed, Oklahoma
Nonpoint source pollution associated with human land use (agriculture and urbanization) is one of the leading causes of impairment to waterways in the United States (EPA, 2000). The primary pollutants associated with agricultural and urban land use are sediment and nutrients which enter nearby streams during rain events and are then carried downstream. These sediments and nutrients may result in water quality issues in the downstream water bodies like increased algal growth or decreased water clarity (e.g. Smith et al., 1999)
The South African Civil Union Act 17 of 2006: A Good Example of the Dangers of Rushing the Legislative Process
Antibullying Interventions in Schools : Ingredients of Effective Programs
Because bullying is a serious problem in Canadian schools, antibullying programs have been widely implemented to redress the problem. School principals in Ontario (N=395) completed a questionnaire to document the severity of bullying, the amount of antiâbullying resources, and the variety of antibullying activities in their schools. Results reveal that reductions in bullying in previous years, sufficiency of resources for resolving bullying, and amounts of antibullying programming were all positively associated antibullying program outcomes. These data suggest that the investment of time, effort, and money in schoolâbased antibullying initiatives can lead to safer and more peaceful schools environments. Key words: bullying, primary prevention, program evaluation Comme lâintimidation est un problĂšme sĂ©rieux dans les Ă©coles canadiennes, des programmes de lutte contre lâintimidation font leur apparition un peu partout. Des directeurs et directrices dâĂ©cole en Ontario (N = 395) ont rempli un questionnaire visant Ă documenter la gravitĂ© du problĂšme, les ressources existantes et les diverses activitĂ©s antiâintimidation mises en place dans les Ă©coles. DâaprĂšs les rĂ©sultats du questionnaire, la rĂ©duction de lâintimidation au cours des annĂ©es prĂ©cĂ©dentes, la pertinence des ressources en place pour faire face aux incidents dâintimidation et le nombre de programmes de lutte contre lâintimidation Ă©taient tous corrĂ©lĂ©s Ă lâamĂ©lioration des rĂ©sultats en la matiĂšre. Ces donnĂ©es semblent indiquer que le temps, les efforts et les fonds investis dans les initiatives antiâintimidation contribuent Ă crĂ©er un climat de paix et rendre les Ă©coles plus sĂ©curitaires. Mots clĂ©s : intimidation, prĂ©vention, Ă©valuation de programmes.
Noninfectious retrovirus particles drive the APOBEC3/Rfv3 dependent neutralizing antibody response.
Members of the APOBEC3 family of deoxycytidine deaminases counteract a broad range of retroviruses in vitro through an indirect mechanism that requires virion incorporation and inhibition of reverse transcription and/or hypermutation of minus strand transcripts in the next target cell. The selective advantage to the host of this indirect restriction mechanism remains unclear, but valuable insights may be gained by studying APOBEC3 function in vivo. Apobec3 was previously shown to encode Rfv3, a classical resistance gene that controls the recovery of mice from pathogenic Friend retrovirus (FV) infection by promoting a more potent neutralizing antibody (NAb) response. The underlying mechanism does not involve a direct effect of Apobec3 on B cell function. Here we show that while Apobec3 decreased titers of infectious virus during acute FV infection, plasma viral RNA loads were maintained, indicating substantial release of noninfectious particles in vivo. The lack of plasma virion infectivity was associated with a significant post-entry block during early reverse transcription rather than G-to-A hypermutation. The Apobec3-dependent NAb response correlated with IgG binding titers against native, but not detergent-lysed virions. These findings indicate that innate Apobec3 restriction promotes NAb responses by maintaining high concentrations of virions with native B cell epitopes, but in the context of low virion infectivity. Finally, Apobec3 restriction was found to be saturable in vivo, since increasing FV inoculum doses resulted in decreased Apobec3 inhibition. By analogy, maximizing the release of noninfectious particles by modulating APOBEC3 expression may improve humoral immunity against pathogenic human retroviral infections
A Comparison Between South Dakota and North American Standard Sampling Gears in Lakes and Reservoirs
A statewide gear comparison was performed in South Dakota during 2013 and 2014 between current South Dakota Department of Game, Fish and Parks (SDGFP) sampling gears (i.e., gill nets and modified fyke nets) and their equivalents described in Standard Methods for Sampling North American Freshwater Fishes (Standard). Adopting Standard gears would provide uniform gear specifications for annual sampling statewide, facilitate data sharing within South Dakota and beyond, and allow for large-scale spatial and temporal analyses relevant to researchers and managers. Sampling was divided between non-Missouri River (non-MR) and Missouri River (MR) systems because gill nets used by SDGFP to sample Missouri River reservoirs were double the length of gill nets used elsewhere in the state and were constructed of multifilament twine instead of monofilament twine. In non-MR systems, SDGFP gill nets had higher catch per unit effort for most species commonly indexed with gill nets including Walleye and Yellow Perch while Standard gill nets selected for larger individuals of most species. In MR systems, gill net CPUE was higher for almost all species captured using SDGFP multifilament reservoir gill nets because SDGFP nets were over three times longer than Standard nets. Standard gill nets with additional large bar-mesh panels selected for larger individuals of most species, including Walleye, than did SDGFP reservoir nets. Monofilament was more efficient than multifilament for almost all species investigated. Modified fyke net catches were similar for many species between net types though Standard nets captured more Black Crappies and SDGFP nets captured more Black Bullheads. Standard modified fyke nets tended to select for larger Black Crappie and Bluegills. In both MR and non-MR systems, conversion factors for lakewide catch per unit effort were developed for each gear type using regression analysis to allow for conversion of historic catch data into equivalent Standard CPUE. Estimates of species diversity and evenness did not differ between SDGFP or Standard gears. Indirect estimates of gill net selectivity were performed for 18 species sampled using Standard gill nets to identify shape of species and mesh-specific selectivity curves, approximate peak modal efficiency for each mesh, and identify overall shape of selectivity curves for all meshes combined. Comparisons of modified fyke nets with restricted and unrestricted throat configurations revealed that catch per unit effort was higher for nets with restricted throats. Subsequent escapement trials confirmed that most Black Crappie and Bluegill escaped from modified fyke nets with unrestricted throats. Together, the paired gear comparisons between SDGFP and Standard gears and additional investigations of Standard gears provided the necessary information to allow for a potential statewide transition to North American Standard sampling gears
An exponential open hashing function based on dynamical systems theory
In this paper an efficient open addressing hash function called exponential hashing is developed using concepts from dynamical systems theory and number theory. A comparison of exponential hashing versus a widely used double hash function is performed using an analysis based on Lyapunov exponents and entropy. Proofs of optimal table parameter choices are provided for a number of hash functions. We also demonstrate experimentally that exponential hashing nearly matches the performance of an optimal double hash function for uniform data distributions and performs significantly better for nonuniform data distributions. We show that exponential hashing exhibits a higher integer Lyapunov exponent and entropy than double hashing for initial data probes which offers one explanation for its improved performance on nonuniform data distributions
High-resolution Elemental Mapping of the Lunar Surface
New instruments and missions are being proposed to study the lunar surface as a result of the resurgence of interest in returning to the Moon. One instrument recently proposed is similar in concept to the x-ray fluorescence detectors flown on Apollo, but utilizes fluorescence from the L- and M-shells rather than the K-shell. This soft X-Ray Flourescence Imager (XRFI) is discussed
A Simple Method to Reduce Interpretation Error of Ages Estimated from Otoliths
We designed and tested a novel otolith viewing apparatus termed the otolith illumination device (OID) to ascertain if its use would result in a reduction of interpretation error as determined by increased precision of age estimates obtained from otoliths of walleye Sander vitreus and smallmouth bass Micropterus dolomieu. Clarity of annuli on otolith sections viewed with the OID was generally greater than clarity of annuli on sections viewed with an alternative method. OID-based age estimates were equally as, and in some instance more precise than ages estimated using the alternative method. Additionally, no systematic differences in coefficients of variation across ages were detected between the OID and alternative methods of fish age estimation. Results suggest that the OID may be useful for inexperienced readers and is a viable option for reducing interpretation error, which may improve reader efficiency and accuracy and precision in estimating fish ages
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