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Search Results: 1 - 10 of 593720 matches for " M. J. Carson "
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Crossing Language Barriers: Using Crossed Random Effects Modelling in Psycholinguistics Research
Robyn J. Carson,Christina M. L. Beeson
Tutorials in Quantitative Methods for Psychology , 2013,
Abstract: The purpose of this paper is to provide a brief review of multilevel modelling (MLM), also called hierarchical linear modelling (HLM), and to present a step-by-step tutorial on how to perform a crossed random effects model (CREM) analysis. The first part provides an overview of how hierarchical data have been analyzed in the past and how they are being analyzed presently. It then focuses on how these types of data have been dealt with in psycholinguistic research. It concludes with an overview of the steps involved in CREM, a form of MLM used for psycholinguistics data. The second part includes a tutorial demonstrating how to conduct a CREM analysis in SPSS, using the following steps: 1) clarify your research question, 2) determine if CREM is necessary, 3) choose an estimation method, 4) build your model, and 5) estimate the model s effect size. A short example on how to report CREM results in a scholarly article is also included.
Short-timescale Variability in the Broadband Emission of the Blazars Mkn421 and Mkn501
M. J. Carson,B. McKernan,T. Yaqoob,D. J. Fegan
Physics , 1999,
Abstract: We analyse ASCA x-ray data and Whipple \gamma-ray data from the blazars Mkn421 and Mkn501 for short-timescale variability. We find no evidence for statistically significant (>3\sigma) variability in these data, in either source, on timescales of less than \sim 10 minutes.
Reduction of Coincident Photomultiplier Noise Relevant to Astroparticle Physics Experiment
M. Robinson,P. K. Lightfoot,M. J. Carson,V. A. Kudryavtsev,N. J. C. Spooner
Physics , 2005, DOI: 10.1016/j.nima.2005.01.319
Abstract: In low background and low threshold particle astrophysics experiments using observation of Cherenkov or scintillation light it is common to use pairs or arrays of photomultipliers operated in coincidence. In such circumstances, for instance in dark matter and neutrino experiments, unexpected PMT noise events have been observed, probably arising from generation of light from one PMT being detected by one or more other PMTs. We describe here experimental investigation of such coincident noise events and development of new techniques to remove them using novel pulse shape discrimination procedures. When applied to data from a low background NaI detector with facing PMTs the new procedures are found to improve noise rejection by a factor of 20 over conventional techniques, with significantly reduced loss of signal events.
Physical Activity and Brain Function in Older Adults at Increased Risk for Alzheimer’s Disease
J. Carson Smith,Kristy A. Nielson,John L. Woodard,Michael Seidenberg,Stephen M. Rao
Brain Sciences , 2013, DOI: 10.3390/brainsci3010054
Abstract: Leisure-time physical activity (PA) and exercise training are known to help maintain cognitive function in healthy older adults. However, relatively little is known about the effects of PA on cognitive function or brain function in those at increased risk for Alzheimer’s disease through the presence of the apolipoproteinE epsilon4 (APOE-ε4) allele, diagnosis of mild cognitive impairment (MCI), or the presence of metabolic disease. Here, we examine the question of whether PA and exercise interventions may differentially impact cognitive trajectory, clinical outcomes, and brain structure and function among individuals at the greatest risk for AD. The literature suggests that the protective effects of PA on risk for future dementia appear to be larger in those at increased genetic risk for AD. Exercise training is also effective at helping to promote stable cognitive function in MCI patients, and greater cardiorespiratory fitness is associated with greater brain volume in early-stage AD patients. In APOE-ε4 allele carriers compared to non-carriers, greater levels of PA may be more effective in reducing amyloid burden and are associated with greater activation of semantic memory-related neural circuits. A greater research emphasis should be placed on randomized clinical trials for exercise, with clinical, behavioral, and neuroimaging outcomes in people at increased risk for AD.
Evaluation of rK39 Rapid Diagnostic Tests for Canine Visceral Leishmaniasis: Longitudinal Study and Meta-Analysis
Rupert J. Quinnell ,Connor Carson,Richard Reithinger,Lourdes M. Garcez,Orin Courtenay
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0001992
Abstract: Background There is a need for sensitive and specific rapid diagnostic tests (RDT) for canine visceral leishmaniasis. The aims of this study were to evaluate the diagnostic performance of immunochromatographic dipstick RDTs using rK39 antigen for canine visceral leishmaniasis by (i) investigating the sensitivity of RDTs to detect infection, disease and infectiousness in a longitudinal cohort study of natural infection in Brazil, and (ii) using meta-analysis to estimate the sensitivity and specificity of RDTs from published studies. Methodology We used a rK39 RDT (Kalazar Detect Canine Rapid Test; Inbios) to test sera collected from 54 sentinel dogs exposed to natural infection in an endemic area of Brazil. Dogs were sampled bimonthly for up to 27 months, and rK39 results compared to those of crude antigen ELISA, PCR, clinical status and infectiousness to sandflies. We then searched MEDLINE and Web of Knowledge (1993–2011) for original studies evaluating the performance of rK39 RDTs in dogs. Meta-analysis of sensitivity and specificity was performed using bivariate mixed effects models. Principal Findings The sensitivity of the rK39 RDT in Brazil to detect infection, disease and infectiousness was 46%, 77% and 78% respectively. Sensitivity increased with time since infection, antibody titre, parasite load, clinical score and infectiousness. Sixteen studies met the inclusion criteria for meta-analysis. The combined sensitivity of rK39 RDTs was 86.7% (95% CI: 76.9–92.8%) to detect clinical disease and 59.3% (37.9–77.6%) to detect infection. Combined specificity was 98.7% (89.5–99.9%). Both sensitivity and specificity varied considerably between studies. Conclusion The diagnostic performance of rK39 RDTs is reasonable for confirmation of infection in suspected clinical cases, but the sensitivity to detect infected dogs is too low for large-scale epidemiological studies and operational control programmes.
Direct Imaging and Spectroscopy of a Young Extrasolar Kuiper Belt in the Nearest OB Association
Thayne Currie,Carey M. Lisse,Marc J. Kuchner,Nikku Madhusudhan,Scott J. Kenyon,Christian Thalmann,Joseph Carson,John H. Debes
Physics , 2015,
Abstract: We describe the discovery of a bright, young Kuiper belt-like debris disk around HD 115600, a $\sim$ 1.4--1.5 M$_\mathrm{\odot}$, $\sim$ 15 Myr old member of the Sco-Cen OB Association. Our H-band coronagraphy/integral field spectroscopy from the \textit{Gemini Planet Imager} shows the ring has a (luminosity scaled) semi major axis of ($\sim$ 22 AU) $\sim$ 48 AU, similar to the current Kuiper belt. The disk appears to have neutral scattering dust, is eccentric (e $\sim$ 0.1--0.2), and could be sculpted by analogues to the outer solar system planets. Spectroscopy of the disk ansae reveal a slightly blue to gray disk color, consistent with major Kuiper belt chemical constituents, where water-ice is a very plausible dominant constituent. Besides being the first object discovered with the next generation of extreme adaptive optics systems (i.e. SCExAO, GPI, SPHERE), HD 115600's debris ring and planetary system provides a key reference point for the early evolution of the solar system, the structure and composition of the Kuiper belt, and the interaction between debris disks and planets.
Second-generation PLINK: rising to the challenge of larger and richer datasets
Christopher C. Chang,Carson C. Chow,Laurent C. A. M. Tellier,Shashaank Vattikuti,Shaun M. Purcell,James J. Lee
Quantitative Biology , 2014, DOI: 10.1186/s13742-015-0047-8
Abstract: PLINK 1 is a widely used open-source C/C++ toolset for genome-wide association studies (GWAS) and research in population genetics. However, the steady accumulation of data from imputation and whole-genome sequencing studies has exposed a strong need for even faster and more scalable implementations of key functions. In addition, GWAS and population-genetic data now frequently contain probabilistic calls, phase information, and/or multiallelic variants, none of which can be represented by PLINK 1's primary data format. To address these issues, we are developing a second-generation codebase for PLINK. The first major release from this codebase, PLINK 1.9, introduces extensive use of bit-level parallelism, O(sqrt(n))-time/constant-space Hardy-Weinberg equilibrium and Fisher's exact tests, and many other algorithmic improvements. In combination, these changes accelerate most operations by 1-4 orders of magnitude, and allow the program to handle datasets too large to fit in RAM. This will be followed by PLINK 2.0, which will introduce (a) a new data format capable of efficiently representing probabilities, phase, and multiallelic variants, and (b) extensions of many functions to account for the new types of information. The second-generation versions of PLINK will offer dramatic improvements in performance and compatibility. For the first time, users without access to high-end computing resources can perform several essential analyses of the feature-rich and very large genetic datasets coming into use.
Lipoprotein particle distribution and skeletal muscle lipoprotein lipase activity after acute exercise
Michael Harrison, Niall M Moyna, Theodore W Zderic, Donal J O’Gorman, Noel McCaffrey, Brian P Carson, Marc T Hamilton
Lipids in Health and Disease , 2012, DOI: 10.1186/1476-511x-11-64
Abstract: Using a randomized cross-over design, very low density lipoprotein (VLDL) responses were evaluated in eight men on the morning after i) an inactive control trial (CON), ii) exercising vigorously on the prior evening for 100?min followed by fasting overnight to maintain an energy and carbohydrate deficit (EX-DEF), and iii) after the same exercise session followed by carbohydrate intake to restore muscle glycogen and carbohydrate balance (EX-BAL).The intermediate, low and high density lipoprotein particle concentrations did not differ between trials. Fasting triglyceride (TG) determined biochemically, and mean VLDL size were lower in EX-DEF but not in EX-BAL compared to CON, primarily due to a reduction in VLDL-TG in the 70–120?nm (large) particle range. In contrast, VLDL-TG was lower in both EX-DEF and EX-BAL compared to CON in the 43–55?nm (medium) particle range. VLDL-TG in smaller particles (29–43?nm) was unaffected by exercise. Because the majority of VLDL particles were in this smallest size range and resistant to change, total VLDL particle concentration was not different between any of these conditions. Skeletal muscle lipoprotein lipase (LPL) activity was also not different across these 3 trials. However, in CON only, the inter-individual differences in LPL activity were inversely correlated with fasting TG, VLDL-TG, total, large and small VLDL particle concentration and VLDL size, indicating a regulatory role for LPL in the non-exercised state.These findings reveal a high level of differential regulation between different sized triglyceride-rich lipoproteins following exercise and feeding, in the absence of changes in LPL activity.Single sessions of exercise transiently reduce serum triglycerides (TG). This exercise effect is not always apparent immediately post-exercise, it can occur after a delay of hours and is generally maximal on the day following intense and prolonged exercise [1,2]. Reductions in serum triglycerides of 18 – 22% are typically observed
Heterogeneities in Leishmania infantum Infection: Using Skin Parasite Burdens to Identify Highly Infectious Dogs
Orin Courtenay equal contributor ,Connor Carson equal contributor,Leo Calvo-Bado,Lourdes M. Garcez,Rupert J. Quinnell
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0002583
Abstract: Background The relationships between heterogeneities in host infection and infectiousness (transmission to arthropod vectors) can provide important insights for disease management. Here, we quantify heterogeneities in Leishmania infantum parasite numbers in reservoir and non-reservoir host populations, and relate this to their infectiousness during natural infection. Tissue parasite number was evaluated as a potential surrogate marker of host transmission potential. Methods Parasite numbers were measured by qPCR in bone marrow and ear skin biopsies of 82 dogs and 34 crab-eating foxes collected during a longitudinal study in Amazon Brazil, for which previous data was available on infectiousness (by xenodiagnosis) and severity of infection. Results Parasite numbers were highly aggregated both between samples and between individuals. In dogs, total parasite abundance and relative numbers in ear skin compared to bone marrow increased with the duration and severity of infection. Infectiousness to the sandfly vector was associated with high parasite numbers; parasite number in skin was the best predictor of being infectious. Crab-eating foxes, which typically present asymptomatic infection and are non-infectious, had parasite numbers comparable to those of non-infectious dogs. Conclusions Skin parasite number provides an indirect marker of infectiousness, and could allow targeted control particularly of highly infectious dogs.
Sex Differences in Wild Chimpanzee Behavior Emerge during Infancy
Elizabeth V. Lonsdorf, A. Catherine Markham, Matthew R. Heintz, Karen E. Anderson, David J. Ciuk, Jane Goodall, Carson M. Murray
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0099099
Abstract: The role of biological and social influences on sex differences in human child development is a persistent topic of discussion and debate. Given their many similarities to humans, chimpanzees are an important study species for understanding the biological and evolutionary roots of sex differences in human development. In this study, we present the most detailed analyses of wild chimpanzee infant development to date, encompassing data from 40 infants from the long-term study of chimpanzees at Gombe National Park, Tanzania. Our goal was to characterize age-related changes, from birth to five years of age, in the percent of observation time spent performing behaviors that represent important benchmarks in nutritional, motor, and social development, and to determine whether and in which behaviors sex differences occur. Sex differences were found for indicators of social behavior, motor development and spatial independence with males being more physically precocious and peaking in play earlier than females. These results demonstrate early sex differentiation that may reflect adult reproductive strategies. Our findings also resemble those found in humans, which suggests that biologically-based sex differences may have been present in the common ancestor and operated independently from the influences of modern sex-biased parental behavior and gender socialization.
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