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.     

A new model of job design: Initial evidence and implications for future research

Clegg and Spencer's (2007) model of job design synthesizes and extends recent conceptions of the job design process by incorporating variables such as knowledge, motivation, and trust into a cyclical and dynamic system. The objective of this study was to examine the sequential organization of variables that comprise the model, as a basis from which to justify further investigations of the model's dynamic properties. Data were collected via questionnaires from 432 participants in two work organizations. Results obtained from structural equation modeling are broadly supportive of the proposed relationships between the variables. Implications of this initial study for future research and practice are discussed. © 2011 Wiley Periodicals, Inc.     

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)     

Effect of operating conditions and liquid physical properties on the size of monodisperse microbubbles produced in a capillary embedded T-junction device

The aim of this study was to investigate the effect of operating parameters such as liquid flow rate, gas inlet pressure, and capillary diameter as well as the influence of the physical properties of the liquid, in particular viscosity, on the generation of monodisperse microbubbles in a circular cross section T-junction device. Aqueous glycerol solutions with viscosities ranging from 1- to 100 mPa s were used in the experiments. The bubble diameter generated was studied for systematically varied combinations of gas inlet pressure, liquid flow rate, and liquid viscosity with a fixed capillary inner diameter of 150 μm for the liquid and gas inlet channels as well as the outlet channel. In addition, the effect of channel geometry on bubble size was studied using capillaries with inner diameters of first 100 and then 200 μm. In all the experiments the distance between the coaxial capillaries at the junction was set to be 200 μm. All the microbubbles produced in this study were highly monodisperse (polydispersity index <1 %) and it was found, as expected, that bubble formation and size were influenced by the ratio of liquid to gas flow rate, capillary size, and liquid viscosity. The experimental data were then compared with empirical scaling laws derived for rectangular cross-section junctions. In contrast with these previous studies, which have found bubble size to be dependent on either the flow rate ratio (the squeezing regime) or capillary number (the dripping regime), in this experimental study bubble size was found to depend on both capillary number and flow ratio.     

The gram-scale synthesis of carbon onions

The combustion of naphthalene has been found to yield gram-scale quantities of carbon onions that are free of impurities and furthermore without the use of catalysts. X-ray diffraction (XRD) indicates that the interlayer spacing between concentric shells of the carbon onions is not uniform across the particle; rather it decreases from a graphite-like 0.34 nm and approaches a diamond-like 0.29 nm interlayer spacing towards the inner layers. The dispersion in the interlayer spacing is believed to result from differing external pressures exerted on the individual nanometer-sized graphitic membranes during formation of the onions. Electron microscopy techniques such as high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy demonstrate the extensive formation of carbon onions. The HRTEM indicates that the onions consist of 50–54 shells, found to be in good agreement with the XRD data.     

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.