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Humanities and Social Sciences50%

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  • many recent studies
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    Selected Abstracts

    Seasonal records of climatic change in annually laminated tufas: short review and future prospects,

    JOURNAL OF QUATERNARY SCIENCE, Issue 5 2005
    J. E. Andrews
    Abstract Many Recent and fossil freshwater tufa stromatolites contain millimetre-scale, alternating laminae of dense micrite and more porous or sparry crystalline calcites. These alternating laminae have been interpreted to represent seasonally controlled differences in the biotic activity of microbes, and/or seasonally controlled changes in the rate of calcification. Either way, couplets of these microbially mediated alternating calcified laminae are generally agreed to represent annual seasonality. Combined stable isotope (,18O and ,13C) and trace element (Mg, Sr, Ba) geochemistry from Recent tufa stromatolites show that seasonal climatic information is available from these calcites. Variability in ,18O (and in one case Mg concentration) has been shown to be controlled primarily by stream temperature change, usually driven by solar insolation. In arid climates, seasonal evaporation can also cause ,18O enrichment by at least 1,. Variability in ,13C results potentially from: (1) seasonal change in plant uptake of 12C-enriched CO2; (2) seasonal change in degassing of 12C-enriched CO2 in the aquifer system; and (3) precipitation of calcite along the aquifer or river flow path, a process that increases ,13C of dissolved inorganic carbon (DIC) in the remaining water. Mechanisms 2 and 3 are linked because calcite precipitates in aquifers where degassing occurs, e.g. air pockets. The latter mechanism for ,13C enrichment has also been shown to cause sympathetic variation between trace element/Ca ratios and ,13C because trace elements with partition coefficients much greater than 1 (e.g. Sr, Ba) remain preferentially in solution. Since degassing in air pockets will be enhanced during decreased recharge when water saturation of the aquifer is lowest, sympathetic variation in trace element/Ca ratios and ,13C is a possible index of recharge and therefore precipitation intensity. High-resolution geochemical data from well-dated tufa stromatolites have great potential for Quaternary palaeoclimate reconstructions, possibly allowing recovery of annual seasonal climatic information including water temperature variation and change in rainfall intensity. However, careful consideration of diagenetic effects, particularly aggrading neomorphism, needs to be the next step. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Evaluation policy and evaluation practice

    NEW DIRECTIONS FOR EVALUATION, Issue 123 2009
    William M. K. Trochim
    The author develops the basic idea of evaluation policy, describes a practical model for development and revision of evaluation policies (including a taxonomy, structure, and set of principles), and suggests critical challenges and opportunities for the future of evaluation policy. An evaluation policy is any rule or principle that a group or organization uses to guide its decisions and actions when doing evaluation. Every entity that engages in evaluation, including government agencies, private businesses, and nonprofit organizations, has evaluation policies. Sometimes they are explicit and written; more often they are implicit and ad hoc principles or norms that have simply evolved over time. Evaluation policies profoundly affect the day-to-day work of all evaluators and ultimately the quality of the programs they evaluate. Many recent and current controversies or conflicts in the field of evaluation can be viewed, at least in part, as a struggle around evaluation policy. Because evaluation policies typically apply across multiple evaluations, influencing policies directly may have systemic and far-reaching effects for practice. Evaluation practice must play a critical role in informing and shaping the development of evaluation policies. © Wiley Periodicals, Inc. [source]

    Global geographies of innovation diffusion: the case of the Australian cattle industry

    THE GEOGRAPHICAL JOURNAL, Issue 1 2010
    MATTHEW TONTS
    The geographies and histories of the introduction of cattle breeds to Australia in the period since white settlement are documented as an example of the diffusion of agricultural innovations. Three phases of development are identified: a colonial expansion phase from the late eighteenth to the early twentieth century during which a number of primarily British cattle breeds were imported by the colonial settlers; an innovative phase in the mid twentieth century when both governments and private interests sought to produce or import new breeds deemed to be better adapted to Australian environments; and a multifunctional phase in recent decades. In this final phase, government deregulation and new technologies, such as the long distance transport of genetic packages, have facilitated the importation and development of many new cattle breeds in Australia. While this has produced a significant rise in the total number of breeds represented nationally, many recent and historic breeds currently exhibit extremely small numbers and a few generally well-established breeds such as Holstein, Hereford and Angus still dominate the national herd. This study of changing breed types and introductions provides some evidence of post-productivism and of a multifunctional transition in that several cattle breeds favoured by hobby farmers and boutique breeders are now represented, but the aggregate numbers for these breeds remain small and the numbers for several of the traditional (or colonial) breeds are currently in decline. Overall, it is apparent that Australia's cattle industry retains a strongly productivist ethos and that, particularly given the country's very great environmental variation, its levels of breed diversity remain low. [source]

    Recent veterinary graduates over the last five decades: recollections and perceptions

    AUSTRALIAN VETERINARY JOURNAL, Issue 11 2005
    TJ HEATH
    Objective To describe the attitudes of veterinary graduates over the last 50 years to their experiences as recent graduates Design A questionnaire, sent by mail. Procedure A questionnaire seeking information on experiences as a recent graduate was sent to about 100 veterinarians who graduated in or about 1950, 1960, 1970, 1980, 1990 and 2000, and 68% responded. Data were entered onto an Excel spreadsheet, and analysed with the SAS System 8 for Windows. Results Most veterinarians who graduated in 1970 and earlier were generally satisfied with their conditions, even though these were often taxing. In the 1970s the cattle industry faltered and rural practice suffered a downturn. Veterinary positions became scarce, and there were few opportunities for graduates to move on from an unsatisfactory workplace - as many were at that time. By 1980 many recent graduates were questioning their decision to study veterinary science. Many of them, working long hours under often stressful conditions, felt that that they were not receiving adequate help or support - or remuneration - from their employers, or respect from their clients. This also afflicted many who graduated in 1990, but by 2000 graduates were reporting an improvement. Their hours of work and the expectations placed on them were more manageable, and the level of help and support, and remuneration, were more acceptable. As a result they found their first year much more enjoyable than had those who had graduated since about 1970. Many of the factors contributing to this improvement resulted from changes in society generally. Specifically, both graduates and employers have become more conscious of what might reasonably be expected, an Award specified minimum levels, the AVA started accrediting New Graduate Friendly Practices, publishing a most informative New Graduate Guide, and helping in other ways. Remuneration, especially when compared with comparable professions, continues to be a source of discontent. Furthermore, despite improved conditions on average, many graduates still suffer under substandard conditions, and these can have an adverse effect on their health and their attitude to their career in veterinary science. Conclusions Average conditions of employment of recent veterinary graduates have improved somewhat after a nadir in the 1970s and 1980s, but they are still substandard for some. Remuneration remains the greatest source of dissatisfaction for recent graduates. [source]