The impacts of cattle access points on deposited sediment levels in headwater streams in Ireland

Cattle access to streams has been linked globally with degradation of stream water quality, driven largely by bank erosion and resultant instream, fine sediment deposition. The majority of evidence on such effects is however based in arid and semiarid regions of the United States and Australia, with few studies relating to cool temperate climates such as Northwest Europe. In this study, “Quorer” resuspendable sediment samples were taken from riffle geomorphic units upstream (control) and at two points downstream (pressure and recovery) of cattle access points in headwater streams in agricultural catchments in Ireland to assess levels of deposited stream sediment. Samples were taken in April/May (2016) prior to the grazing season and in October (2016) at the end of the grazing season. Sites in good‐high ecological status catchments and less than good ecological status catchments were included in the study. Higher levels of sediment were found downstream of cattle access points in both good‐high status and less than good status catchments; however, the impacts of access points were spatially confined to, in most cases, the area immediately downstream of the point of access. There was a strong correlation between deposited sediment mass and organic matter (OM) mass, with levels of OM increasing linearly with deposited sediment mass. Levels of measured sediment were negatively correlated with riparian habitat health (measured using a qualitative habitat assessment). The results of this study highlight the need for measures to prevent cattle access to headwater streams where access points can be many in order to manage local habitat quality and downstream water quality issues.     

Molecular beam studies of fullerenes

A number of molecular beam experiments with the fullerenes are described. Such experiments allow a detailed probing of the interactions between fullerenes and other species and among the fullerenes themselves. Emphasis is placed on work involving photophysics and collisional interactions of the fullerenes.     

Website accessibility: a cross-sector comparison

The Web has transformed the way organizations interact with clients, customers, and constituents. A large portion of these groups is often neglected, namely people with disabilities. This study compares federal government, non-profit organization (NPO), and corporate homepages accessibility to determine how accessible these websites are to people with disabilities and how they compare to each other. The results indicate that federal homepages (23%), which are mandated to be accessible, are significantly more accessible than NPO (11%) and corporate homepages (6%).

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The Relations Between Contextual Risk, Earned Income, and the School Adjustment of Children From Economically Disadvantaged Families.

This longitudinal study examined the relations between multiple risk indexes representing contextual adversity, income-to-needs ratios, and the elementary school adjustment of children from economically disadvantaged families. The results provide evidence for volatility in family circumstances over 2-year intervals from preschool to 5th grade, for relations between the contextual risk indexes and change in externalizing behavior, and for relations between the income-to-needs ratios and change in academic competence. The results also show differences in the timing of the effects. Little evidence was found for persistence effects. Theoretical implications concern conceptualizations of the diverse and dynamic nature of the family circumstances experienced by disadvantaged children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and Disability: Implications for the Housing Industry and Housing Policy in the United States

Problem: The elderly population of the United States is large and growing rapidly. Since disability rates increase with age, population aging will bring substantial increases in the number of disabled persons and have a significant impact on the nation's housing needs.

Purpose: We demonstrate the impact of population growth and aging on the projected number of households with at least one disabled resident and estimate the probability that a newly built single-family detached unit will have at least one disabled resident during its expected lifetime.

Methods: We calculate disability rates using two alternative measures of disability and construct projections of the number of households with at least one disabled resident. We develop and apply a technique for estimating the probability that a newly built single-family detached unit will house at least one disabled resident using data on the average lifespan of those units, the average length of residence for households occupying those units, and the projected proportion of households with at least one disabled resident.

Results and conclusions: Under our medium assumptions, we project that 21% of households will have at least one disabled resident in 2050 using our first disability measure (physical limitation) and 7% using our second (self-care limitation). We estimate that there is a 60% probability that a newly built single-family detached unit will house at least one disabled resident during its expected lifetime using our first measure, and a 25% probability using our second measure. When disabled visitors are accounted for, the probabilities rise to 91% and 53%, respectively. Given the desire of most people to live independently for as long as possible, these numbers reflect a large and growing need for housing units with features that make them accessible to disabled persons.

Takeaway for practice: The lack of accessible housing provides an opportunity for homebuilders to develop and market products that meet the needs of an aging population. In light of concerns about the civil rights of people with disabilities and the high public cost of nursing home care, housing accessibility is a critical issue for planners and policymakers as well. We believe planners should broaden their vision of the built environment to include the accessibility of the housing stock.

Research support: None.     

Novel electrohydrodynamic preparation of porous chitosan particles for drug delivery

Uniform spherical chitosan particles of size <10 μm in diameter are important in drug delivery applications due to their excellent biocompability and biodegradability. A high concentration of chitosan in the particles can help to control the release of drugs and methods for processing high viscosity chitosan solutions are therefore required. In principle, any type of polymer, whether hydrophobic or hydrophilic, can be electrosprayed to obtain monodisperse particles of diameter <10 μm. In practice, however, electrospraying of biopolymers having viscosities of >100 mPa s results in particles >10 μm diameter. In this study, by reducing surface tension of a high viscosity chitosan suspension, it was found that smaller diameter particles could be prepared. Chitosan solutions were electrosprayed in the stable cone-jet mode to systematically study the relationship between particle diameter, viscosity and surface tension. Increasing viscosity resulted in larger diameter particles with a broad size distribution, but decreasing surface tension had the opposite effect. Results show that a chitosan solution having a viscosity of ~80 mPa s can be used to prepare chitosan particles of diameter ~2.5 μm which on drying reduced to particles of 500 nm.