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.     

Effects of crack depth on elastic-plastic fracture toughness

Short crack test specimens (a/W 0.50) are frequently employed when conventional deep crack specimens are either inappropriate or impossible to obtain, for example, in testing of particular microstructures in weldments and in-service structures containing shallow surface flaws. Values of elastic-plastic fracture toughness, here characterized by the crack tip opening displacement (CTOD), are presented for square (cross-section) three-point bend specimens with a/W ratios of 0.15 and 0.50 throughout the lower-shelf and lower-transition regions. Three dimensional, finite-element analyses are employed to correlate the measured load and crack mouth opening displacement (CMOD) values to the corresponding CTOD values, thus eliminating a major source of experimental difficulty in previous studies of shallow crack specimens. In the lower-transition region, where extensive plasticity (but no ductile crack growth) precedes brittle fracture, critical CTOD values for short crack specimens are significantly larger (factor of 2–3) than the CTOD values for deep crack specimens at identical temperatures. Short crack specimens are shown to exhibit increased toughness at the initiation of ductile tearing and decreased brittle-to-ductile transition temperatures. Numerical analyses for the two a/W ratios reveal large differences in stress fields ahead of the crack tip at identical CTOD levels which verify the experimentally observed differences in critical CTOD values. Correlations of the predicted stresses with measured critical CTOD values demonstrate the limitations of single-parameter fracture mechanics (as currently developed) to characterize the response.     

Optics clustered to output unique solutions: a multi-laser facility for combined single molecule and ensemble microscopy

Optics clustered to output unique solutions (OCTOPUS) is a microscopy platform that combines single molecule and ensemble imaging methodologies. A novel aspect of OCTOPUS is its laser excitation system, which consists of a central core of interlocked continuous wave and pulsed laser sources, launched into optical fibres and linked via laser combiners. Fibres are plugged into wall-mounted patch panels that reach microscopy end-stations in adjacent rooms. This allows multiple tailor-made combinations of laser colours and time characteristics to be shared by different end-stations minimising the need for laser duplications. This setup brings significant benefits in terms of cost effectiveness, ease of operation, and user safety. The modular nature of OCTOPUS also facilitates the addition of new techniques as required, allowing the use of existing lasers in new microscopes while retaining the ability to run the established parts of the facility. To date, techniques interlinked are multi-photon/multicolour confocal fluorescence lifetime imaging for several modalities of fluorescence resonance energy transfer (FRET) and time-resolved anisotropy, total internal reflection fluorescence, single molecule imaging of single pair FRET, single molecule fluorescence polarisation, particle tracking, and optical tweezers. Here, we use a well-studied system, the epidermal growth factor receptor network, to illustrate how OCTOPUS can aid in the investigation of complex biological phenomena.     

Evolution of elastic modulus in roll forming

Roll forming is a continuous process in which a flat strip is incrementally bent to a desired profile. This process is increasingly used in automotive industry to form High Strength Steel (HSS) and Advanced High Strength Steel (AHSS) for structural components. Because of the large variety of applications of roll forming in the industry, Finite Element Analysis (FEA) is increasingly employed for roll forming process design. Formability and springback are two major concerns in the roll forming AHSS materials. Previous studies have shown that the elastic modulus (Young’s modulus) of AHSS materials can change when the material undergoes plastic deformation and the main goal of this study is to investigate the effect of a change in elastic modulus during forming on springback in roll forming. FEA has been applied for the roll forming simulation of a V-section using material data determined by experimental loading-unloading tests performed on mild, XF400, and DP780 steel. The results show that the reduction of the elastic modulus with pre-strain significantly influences springback in the roll forming of high strength steel while its effect is less when a softer steel is formed.     

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.