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Search Results: 1 - 10 of 94571 matches for " Matthew W. McDonald "
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Corrigendum: Nanocrystalline diamond surfaces for adhesion and growth of primary neurons, conflicting results and rational explanation
Matthew Mcdonald
Frontiers in Neuroengineering , 2014, DOI: 10.3389/fneng.2014.00037
Abstract: The article "Nanocrystalline diamond surfaces for adhesion and growth of primary neurons, conflicting results and rational explanation" was published 11 June 2014, with myself as the second author. It came to my attention through a friend that my name is spelled incorrectly, which I did not notice during the review process. On the paper, currently my name is spelled as: Mathew McDonald. The correct spelling is: Matthew McDonald
Flexibility of Older Adults Aged 55–86 Years and the Influence of Physical Activity
Liza Stathokostas,Matthew W. McDonald,Robert M. D. Little,Donald H. Paterson
Journal of Aging Research , 2013, DOI: 10.1155/2013/743843
Abstract: Cross-sectional age-related differences in flexibility of older adults aged 55–86 years of varying activity levels were examined. Shoulder abduction and hip flexion flexibility measurements were obtained from 436 individuals (205 men, years; 231 women, years). Total physical activity was assessed using the Minnesota Leisure-Time Physical Activity Questionnaire. Shoulder abduction showed a significant decline averaging 5?degrees/decade in men and 6?degrees/decade in women. Piecewise linear regression showed an accelerated decline in men starting at the age of 71 years of 0.80?degrees/year, whereas in women the onset of decline (0.74?degrees/year) was 63 years. Men and women showed a significant decline in hip flexion (men: 6?degrees/decade; women: 7?degrees/decade). Piecewise linear regression revealed a rate of decline of 1.16?degrees/year beginning at 71 years in men and in women a single linear decline of 0.66?degrees/year. Multiple regression analysis showed that age and physical activity accounted for only 9% of the variance in hip flexion in women and 10% in men, with age but not physical activity remaining significant. Similarly for shoulder abduction, age was significant but not physical activity, in a model that described 8% of the variance for both sexes. 1. Introduction As indicated in a recent systematic review by our group [1], there is conflicting information regarding both the relationship between flexibility training interventions and functional outcomes and the relationship between improved flexibility and daily functioning; health benefits have not yet been established. The comparison of studies in this area to provide a prescription of the flexibility is complicated by the variety of limb ranges of motion studied, testing procedures utilized, and methods of assessing physical activity levels. Furthermore, this component of physical health has been somewhat neglected or forgotten in the current literature despite the lack of evidence for recommendations of the amount and type of flexibility needed for health in older adults. Further, despite this lack of a synthesis of the literature to support the recommendation of the inclusion of a flexibility component to older adult exercise programs, many older adult activity programs place a considerable emphasis on flexibility. The present study attempts to add additional insight to this area by presenting the relationship between declines in flexibility across age and functional outcomes in a large sample of individuals representing the older adult age range. Joint flexibility may decrease
Facebook in Vietnam: Uses, Gratifications & Narcissism  [PDF]
Brian McCauley, Sarah Gumbley, Giovanni Merola, Matthew McDonald, Truc Do
Open Journal of Social Sciences (JSS) , 2016, DOI: 10.4236/jss.2016.411006
The purpose of this study was to create a conceptual framework and to collect some pilot data in order to underpin future research on how the Vietnamese use Facebook in their day-to-day lives. A number of key points were observed in this study, which informed the framework. Firstly, there is a paucity of research on this topic, that Facebook users in Vietnam (population 90 million) rank as some of the heaviest consumers in the world, and Vietnamese cultural traditions and values need to be acknowledged given these differences when compared to other nations and how this might influence Facebook use. Given the studies focus on users, the theory on “uses and gratifications” was employed in order to understand how Facebook satisfies the needs of its Vietnamese users. An important component in this theory is the way in which Facebook allows posting of material related to the enhancement of the “self”, which has the potential to satisfy ego driven needs in the form of narcissism. However, narcissism and its links with Facebook have only recently been systematically studied in Asian countries, predominately in China. In conclusion, the conceptual framework and analysis of the pilot data produced a number of interrelated constructs (e.g. socializing, social enhancement, entertainment) that provide a baseline or foundation from which a longer-term program of empirical research can be conducted on Facebook use in Vietnam1.
A Practical, Cost-effective Method for Recruiting People Into Healthy Eating Behavior Programs
Paul W. McDonald, PhD
Preventing Chronic Disease , 2007,
Abstract: IntroductionThe population impact of programs designed to develop healthy eating behaviors is limited by the number of people who use them. Most public health providers and researchers rely on purchased mass media, which can be expensive, on public service announcements, or clinic-based recruitment, which can have limited reach. Few studies offer assistance for selecting high-outreach and low-cost strategies to promote healthy eating programs. The purpose of this study was 1) to determine whether classified newspaper advertising is an effective and efficient method of recruiting participants into a healthy eating program and 2) to determine whether segmenting messages by transtheoretical stage of change would help engage individuals at all levels of motivation to change their eating behavior. MethodsFor 5 days in 1997, three advertisements corresponding to different stages of change were placed in a Canadian newspaper with a daily circulation of 75,000.ResultsThere were 282 eligible people who responded to newspaper advertisements, and the cost was Can $1.11 (U.S. $0.72) per recruit. This cost compares favorably with the cost efficiency of mass media, direct mail, and other common promotional methods. Message type was correlated with respondent’s stage of change, and this correlation suggested that attempts to send different messages to different audience segments were successful. DiscussionClassified advertisements appear to be a highly cost-efficient method for recruiting a diverse range of participants into healthy eating programs and research about healthy eating.
Bias of the Random Forest Out-of-Bag (OOB) Error for Certain Input Parameters  [PDF]
Matthew W. Mitchell
Open Journal of Statistics (OJS) , 2011, DOI: 10.4236/ojs.2011.13024
Abstract: Random Forest is an excellent classification tool, especially in the –omics sciences such as metabolomics, where the number of variables is much greater than the number of subjects, i.e., “n << p.” However, the choices for the arguments for the random forest implementation are very important. Simulation studies are performed to compare the effect of the input parameters on the predictive ability of the random forest. The number of variables sampled, m-try, has the largest impact on the true prediction error. It is often claimed that the out-of-bag error (OOB) is an unbiased estimate of the true prediction error. However, for the case where n << p, with the default arguments, the out-of-bag (OOB) error overestimates the true error, i.e., the random forest actually performs better than indicated by the OOB error. This bias is greatly reduced by subsampling without replacement and choosing the same number of observations from each group. However, even after these adjustments, there is a low amount of bias. The remaining bias occurs because when there are trees with equal predictive ability, the one that performs better on the in-bag samples will perform worse on the out-of-bag samples. Cross-validation can be performed to reduce the remaining bias.
Using Evidence Based Home Visiting for Preventing Intergenerational Adverse Childhood Experiences  [PDF]
Makenzie A. Phillips, Theodore W. McDonald, Dorothy I. Kishbaugh
Psychology (PSYCH) , 2017, DOI: 10.4236/psych.2017.814159
Abstract: A body of literature has amassed in recent years examining risk factors and outcomes for children who have experienced various forms of trauma. Childhood maltreatment in various forms has commonly been termed adverse childhood experiences (ACEs), which are severe enough to negatively impact mental and physical health in both childhood and adulthood, as well as lead to a variety of undesirable life outcomes for affected adults. Less has been studied regarding the cyclical nature of child maltreatment and the effects that parents’ own history of childhood trauma may have on their children’s experience of trauma. Recent research has evaluated intervention strategies such as evidence-based home visiting (EBHV) programs for mothers and infants/toddlers that address this phenomenon and aims to interrupt the cycle of maltreatment. The benefits of home visiting will be reviewed and policy and cost implications related to preventive intervention are discussed.
The State of the Warm and Cold Gas in the Extreme Starburst at the Core of the Phoenix Galaxy Cluster (SPT-CLJ2344-4243)
Michael McDonald,A. M. Swinbank,Alastair C. Edge,David J. Wilner,Sylvain Veilleux,Bradford A. Benson,Michael T. Hogan,Daniel P. Marrone,Brian R. McNamara,Lisa H. Wei,Matthew B. Bayliss,Marshall W. Bautz
Physics , 2013, DOI: 10.1088/0004-637X/784/1/18
Abstract: [Abridged] We present new optical integral field spectroscopy (Gemini South) and submillimeter spectroscopy (Submillimeter Array) of the central galaxy in the Phoenix cluster (SPT-CLJ2344-4243). This cluster was previously reported to have a massive starburst (~800 Msun/yr) in the central, brightest cluster galaxy, most likely fueled by the rapidly-cooling intracluster medium. These new data reveal a complex emission-line nebula, extending for >30 kpc from the central galaxy. The total Halpha luminosity, assuming Halpha/Hbeta = 2.85, is L_Ha = 7.6 +/- 0.4 x10^43 erg/s, making this the most luminous emission line nebula detected in the center of a cool core cluster. Overall, the relative fluxes of the low-ionization lines (e.g., [O II], Hbeta) to the UV continuum are consistent with photoionization by young stars. In both the center of the galaxy and in a newly-discovered highly-ionized plume to the north of the galaxy, the ionization ratios are consistent with both shocks and AGN photoionization. We speculate that this extended plume may be a galactic wind, driven and partially photoionized by both the starburst and central AGN. We find evidence for shocks throughout the ISM of the central galaxy, most likely driven by a combination of stellar winds from massive young stars, core-collapse supernovae, and the central AGN. In addition to the warm, ionized gas, we detect a substantial amount of cold, molecular gas via the CO(3-2) transition, coincident in position with the galaxy center. We infer a molecular gas mass of M_H2 = 2.2 +/- 0.6 x10^10 Msun, which implies that the starburst will consume its fuel in ~30 Myr if it is not replenished. The combination of the high level of turbulence in the warm phase and the high L_IR/M_H2 ratio suggests that this violent starburst may be in the process of quenching itself.
Quantification of drought tolerance in Ethiopian common bean varieties  [PDF]
Asrat Asfaw, Matthew W. Blair
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.52016

Understanding the level of drought tolerance of the varieties available in each country is of paramount importance for breeding common bean for drought adaptation. The goal of this study was to evaluate 25 common bean genotypes of which 24 were released/recommended varieties for production by farmers and one was a drought tolerant check. The genotypes were planted at two sites in Ethiopia, Hawasssa and Amaro, using variable sowing dates, one that was early to avoid drought and one that was late to expose the crop to drought. The experiments were repeated over two years in Hawassa and one year in Amaro. This resulted in treatments with high and low total seasonal rainfall and six environments for analysis. The impact of drought stress on the trait expression of the varieties was not uniform across traits assessed and varieties tested. The effect of drought on photosynthate translocation and partitioning traits was much greater than on yield component traits in the varieties studied. This indicating less breeding efforts has been made in improving the varieties ability to mobilize photosynthate to the developing grain as compared to the yield component traits. Drought tolerant varieties like Hawassa Dume maintained better photosynthate translocation and partitioning than the drought sensitive varieties like Brown Speckled bean. Hawassa Dume also showed better yield stability and performed well under both drought stress and nonstress conditions. Our results indicate the relevance of high levels of photosynthate translocation and partitioning as an effective selection objective for improving drought tolerance in common bean. The information generated on the drought tolerance of the available varieties should help in the design of a breeding strategy that incorporates adaptation traits with commercial characteristics preferred by common bean farmers for varieties to be grown in diverse environments.

Exploring cross-sectional associations between common childhood illness, housing and social conditions in remote Australian Aboriginal communities
Ross Bailie, Matthew Stevens, Elizabeth McDonald, David Brewster, Steve Guthridge
BMC Public Health , 2010, DOI: 10.1186/1471-2458-10-147
Abstract: Hierarchical multi-level analysis of association between carer report of common childhood illnesses and functional and hygienic state of housing infrastructure, socio-economic, psychosocial and health related behaviours using baseline survey data from a housing intervention study.Multivariate analysis showed a strong independent association between report of respiratory infection and overall functional condition of the house (Odds Ratio (OR) 3.00; 95%CI 1.36-6.63), but no significant association between report of other illnesses and the overall functional condition or the functional condition of infrastructure required for specific healthy living practices. Associations between report of child illness and secondary explanatory variables which showed an OR of 2 or more included: for skin infection - evidence of poor temperature control in the house (OR 3.25; 95%CI 1.06-9.94), evidence of pests and vermin in the house (OR 2.88; 95%CI 1.25-6.60); for respiratory infection - breastfeeding in infancy (OR 0.27; 95%CI 0.14-0.49); for diarrhoea/vomiting - hygienic state of food preparation and storage areas (OR 2.10; 95%CI 1.10-4.00); for ear infection - child care attendance (OR 2.25; 95%CI 1.26-3.99).These findings add to other evidence that building programs need to be supported by a range of other social and behavioural interventions for potential health gains to be more fully realised.Children in remote Australian Aboriginal communities experience exceptionally high rates of common childhood infections including otitis media, skin and respiratory infections and gastroenteritis [1-4]. These infections have serious consequences, including high rates of chronic suppurative otitis media [3], bronchiectasis [5], rheumatic heart disease [6,7] and impaired growth and development [2,8] permanent hearing loss [9] and consequent poor educational outcomes [10]. These infections in childhood contribute to high rates and early onset of chronic disease in adulthood [11] and to the 1
Dystrophic Changes in Extraocular Muscles after Gamma Irradiation in mdx:utrophin+/? Mice
Abby A. McDonald, Matthew D. Kunz, Linda K. McLoon
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0086424
Abstract: Extraocular muscles (EOM) have a strikingly different disease profile than limb skeletal muscles. It has long been known that they are spared in Duchenne (DMD) and other forms of muscular dystrophy. Despite many studies, the cause for this sparing is not understood. We have proposed that differences in myogenic precursor cell properties in EOM maintain normal morphology over the lifetime of individuals with DMD due to either greater proliferative potential or greater resistance to injury. This hypothesis was tested by exposing wild type and mdx:utrophin+/? (het) mouse EOM and limb skeletal muscles to 18 Gy gamma irradiation, a dose known to inhibit satellite cell proliferation in limb muscles. As expected, over time het limb skeletal muscles displayed reduced central nucleation mirrored by a reduction in Pax7-positive cells, demonstrating a significant loss in regenerative potential. In contrast, in the first month post-irradiation in the het EOM, myofiber cross-sectional areas first decreased, then increased, but ultimately returned to normal compared to non-irradiated het EOM. Central nucleation significantly increased in the first post-irradiation month, resembling the dystrophic limb phenotype. This correlated with decreased EECD34 stem cells and a concomitant increase and subsequent return to normalcy of both Pax7 and Pitx2-positive cell density. By two months, normal het EOM morphology returned. It appears that irradiation disrupts the normal method of EOM remodeling, which react paradoxically to produce increased numbers of myogenic precursor cells. This suggests that the EOM contain myogenic precursor cell types resistant to 18 Gy gamma irradiation, allowing return to normal morphology 2 months post-irradiation. This supports our hypothesis that ongoing proliferation of specialized regenerative populations in the het EOM actively maintains normal EOM morphology in DMD. Ongoing studies are working to define the differences in the myogenic precursor cells in EOM as well as the cellular milieu in which they reside.
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