Publications by authors named "David McKeown"

Non-crystalline silica mineraloids are essential to life on Earth as they provide architectural structure to dominant primary producers, such as plants and phytoplankton, as well as to protists and sponges. Due to the difficulty in characterizing and quantifying the structure of highly disordered X-ray amorphous silica, relatively little has been done to understand the mineralogy of biogenic silica and how this may impact the material properties of biogenic silica, such as hardness and strength, or how biosilica might be identified and differentiated from its inorganic geological counterparts. Typically, geologically formed opal-A and hyalite opal-A are regarded as analogs to biogenic silica, however, some spectroscopic and imaging studies suggest that this might not be a reasonable assumption.

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(1) Background: Postural sway is frequently used to quantify human postural control, balance, injury, and neurological deficits. However, there is considerably less research investigating the value of the metric in horses. Much of the existing equine postural sway research uses force or pressure plates to examine the centre of pressure, inferring change at the centre of mass (COM).

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OBJECT There is no consensus regarding the appropriate treatment of sacral giant cell tumor (GCT). There are 3 main management problems: tumor control, neurological loss, and pelvic instability. The objective of this study was to examine oncological, neurological, and structural outcomes of sacral GCT after intralesional excision and local intraoperative adjunctive treatment.

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The healthcare system in Canada is undergoing significant transformation in response to three major interrelated pressures: the overall burden of illness is rising, patients are getting poor quality of care and healthcare costs are inexorably rising. One idea to guide this change is to transform the primary care system into a community-based primary healthcare (CBPH) system. This paper discusses, in particular, the readiness of public health to participate in the transformation to a CBPH system.

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The aim of this study was to investigate the benefits of a low-volume, vigorous intensity bench stepping programme in sedentary middle-aged adults. Thirty-one healthy but sedentary adults (12 men; 55-64 years) took part in the study. Participants accumulated up to 9 min per day of stepping exercise on three days per week over the 4-week experimental period.

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Postural sway during quiet standing is associated with falls risk in older adults. The aim of this study was to investigate the utility of a range of accelerometer-derived parameters of centre of mass (COM) displacement in identifying older adults at risk of falling. A series of instrumented standing balance trials were performed to investigate postural control in a group of older adults, categorised as fallers or non-fallers.

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We investigated three methods for estimating centre of pressure excursions, as measured using a portable pressure sensor matrix, in order to deploy similar technology into the homes of older adults for longitudinal monitoring of postural control and falls risk. We explored the utility of these three methods as markers of falls risk in a cohort of 120 community dwelling older adults with and without a history of falls (65 fallers, 55 non-fallers). A number of standard quantitative balance parameters were derived using each centre of pressure estimation method.

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Falls are the most common cause of injury and hospitalization and one of the principal causes of death and disability in older adults worldwide. Measures of postural stability have been associated with the incidence of falls in older adults. The aim of this study was to develop a model that accurately classifies fallers and non-fallers using novel multi-sensor quantitative balance metrics that can be easily deployed into a home or clinic setting.

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Recent advances in body-worn sensor technology have increased the scope for harnessing quantitative information from the timed-up-and-go test (TUG), well beyond simply the time taken to perform the test. Previous research has shown that the quantitative TUG method can differentiate fallers from non-fallers with greater success than the manually timed TUG or the Berg Balance Test. In order to advance this paradigm of falls risk estimation it is necessary to investigate the robustness of the quantitative TUG variables.

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Despite its widespread use in performance assessment, the reliability of vertical jump in an ageing population has not been addressed properly. The aim of the present study was to assess intra- and inter-day reliability of countermovement jump in healthy middle-aged (55-65 years) and older (66-75 years) men and women. Eighty-two participants were recruited and asked to perform countermovement jumps on two different occasions interspersed by 4 weeks.

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Child poverty in Canada is a significant public health concern. Because child development during the early years lays the foundation for later health and development, children must be given the best possible start in life. Family income is a key determinant of healthy child development.

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Technetium, found in some nuclear wastes (such as those generated from spent fuel reprocessing), is of particular concern with regard to long-term waste storage because of its long half-life (2.13 x 10(5) years) and high mobility in the environment. One method of stabilization of such waste is through vitrification to produce a durable borosilicate glass matrix.

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