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Search Results: 1 - 10 of 504001 matches for " Carlson David A "
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Emerging Object Representations in the Visual System Predict Reaction Times for Categorization
J. Brendan Ritchie?,David A. Tovar?,Thomas A. Carlson
PLOS Computational Biology , 2015, DOI: 10.1371/journal.pcbi.1004316
Abstract: Recognizing an object takes just a fraction of a second, less than the blink of an eye. Applying multivariate pattern analysis, or “brain decoding”, methods to magnetoencephalography (MEG) data has allowed researchers to characterize, in high temporal resolution, the emerging representation of object categories that underlie our capacity for rapid recognition. Shortly after stimulus onset, object exemplars cluster by category in a high-dimensional activation space in the brain. In this emerging activation space, the decodability of exemplar category varies over time, reflecting the brain’s transformation of visual inputs into coherent category representations. How do these emerging representations relate to categorization behavior? Recently it has been proposed that the distance of an exemplar representation from a categorical boundary in an activation space is critical for perceptual decision-making, and that reaction times should therefore correlate with distance from the boundary. The predictions of this distance hypothesis have been born out in human inferior temporal cortex (IT), an area of the brain crucial for the representation of object categories. When viewed in the context of a time varying neural signal, the optimal time to “read out” category information is when category representations in the brain are most decodable. Here, we show that the distance from a decision boundary through activation space, as measured using MEG decoding methods, correlates with reaction times for visual categorization during the period of peak decodability. Our results suggest that the brain begins to read out information about exemplar category at the optimal time for use in choice behaviour, and support the hypothesis that the structure of the representation for objects in the visual system is partially constitutive of the decision process in recognition.
How Active Are Older Americans?
Judy Kruger, PhD,Susan A. Carlson, MS,David Buchner, MD
Preventing Chronic Disease , 2007,
Abstract: IntroductionRegular physical activity can reduce age-related functional decline, as well people’s risk for chronic diseases such as coronary heart disease, hypertension, colon cancer, and diabetes. The objective of this study was to estimate the level of participation in aerobic, muscle-strengthening, and flexibility activities among Americans aged 50 years or older.MethodsUsing population-based data from the 2001 National Health Interview Survey, we classified qualified respondents (N = 11,969) according to whether they met the activity criteria used in Healthy People 2010 goals for leisure-time participation in regular aerobic physical activity, vigorous-intensity aerobic activity, strength-training activity, and flexibility activity. We also classified respondents according to their level of aerobic activity (i.e., inactive, insufficiently active, and regularly active).ResultsWe estimated that 46.4% of older Americans engaged in no leisure-time aerobic activity; that 26.1% were regularly active (participated in light- to moderate-intensity aerobic activities at least 5 days per week for at least 30 minutes or vigorous-intensity activities at least 3 days per week for at least 20 minutes); that 16.2% participated in vigorous-intensity aerobic activities at least 3 days per week for at least 20 minutes; that 13.7% participated in strength-training activities at least 2 days per week; and that 24.5% participated in flexibility activities at least 1 day per week. Among the 26.1% of older Americans who were regularly active, 30.5% engaged in strengthen-training activities at least 2 days per week. Overall, only 8.2% of older Americans met the criteria for both aerobic and strength-training activity.ConclusionAs of 2001, the percentage of older Americans who met recommended activity levels of physical activity were well below the goals for U.S. adults in Healthy People 2010. Further efforts are needed to encourage older Americans to engage in aerobic activities and in strengthening and flexibility activities.
A pilot study for augmenting atomoxetine with methylphenidate: safety of concomitant therapy in children with attention-deficit/hyperactivity disorder
Carlson Gabrielle A,Dunn David,Kelsey Douglas,Ruff Dustin
Child and Adolescent Psychiatry and Mental Health , 2007, DOI: 10.1186/1753-2000-1-10
Abstract: Background This study examined augmenting atomoxetine with extended-release methylphenidate in children whose attention-deficit/hyperactivity disorder (ADHD) previously failed to respond adequately to stimulant medication. Methods Children with ADHD and prior stimulant treatment (N = 25) received atomoxetine (1.2 mg/kg/day) plus placebo. After 4 weeks, patients who were responders (n = 4) were continued on atomoxetine/placebo while remaining patients were randomly assigned to either methylphenidate (ATX/MPH) (1.1 mg/kg/day) or placebo augmentation (ATX/PB) for another 6 weeks. Patients and sites were blind to timing of active augmentation. Safety measures included vital signs, weight, and adverse events. Efficacy was assessed by ADHD rating scales. Results Categorical increases in vital signs occurred for 5 patients (3 patients in ATX/MPH, 2 patients in ATX/PBO). Sixteen percent discontinued the study due to AE, but no difference between augmentation groups. Atomoxetine treatment was efficacious on outcome measures (P ≤ .001), but methylphenidate did not enhance response. Conclusion Methylphenidate appears to be safely combined with atomoxetine, but conclusions limited by small sample. With atomoxetine treatment, 43% of patients achieved normalization on ADHD ratings.
Improving STEM Education in Research: Preliminary Report on the Development of a Computer-Assisted Student-Mentor Research Community  [PDF]
David Rios, Artem Chebotko, Christine Reilly, Ralph Carlson, Emmett Tomai, Amy A Weimer, Nicholas Weimer, Thomas Pearson, Francis Andoh-Baidoo, Robert Winkle, David Ammons, Joanne Rampersad
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.35090
Abstract: Research education in STEM disciplines currently suffers from 1) The inability to feasibly collect highly detailed data on both the student’s and mentor’s activities; 2) The lack of tools to assist students and mentors in organizing and managing their research activities and environments; and 3) The inability to correlate a student’s assessment results with their actual research activities. Together these three problems act to impede both the improvement and educational quality of student research experiences. We propose a computer-assisted student-mentor research community as a solution to these problems. Within this community setting, students and their mentors are provided tools to make their work easier, much like a word processor makes writing a letter easier. Through their use of these tools, details of student-mentor activities are automatically recorded in a relational database, without burdening users with the responsibility of archiving data. Equally important, student assessments of outcome can be directly related to student activity, allowing educators to identify practices resulting in successful research experiences. Community tools also facilitate the use of labor-intensive teaching laboratories involving real inquiry-based research. The community structure has the added benefit of allowing students to see, communicate and interact more freely with other students and their projects, thus enriching the student’s research experience. We provide herein a preliminary report on the development and testing of a prototype, student-mentor research community, and present its tools, an assessment of student interest in participating in the community, and discuss its further development into a nationally-available student-mentor research community.
Arctic Ocean Science and Outreach: A Perspective from the International Polar Year Programme Office
David Carlson
Oceanography , 2011,
Abstract: During its formative months, I often faced the question whether this fourth IPY would include "kayaks" (my codeword for small, individual, and implicitly flexible and innovative research projects) or exclusively "icebreakers" (a codeword for large multi-investigator projects, by implication complex planned efforts, generally controlled by the established polar scientific order). The question of project scope arose in Arctic science meetings and penetrated, for a time, the public media. I maintained that innovation and creativity would occur throughout IPY, regardless of size of project or platform. As steward of the IPY International Office, I argued publicly for the widest inclusion of ideas and proposals, from groups large and small.
Cuticular hydrocarbons of Chagas disease vectors in Mexico
Juárez, M Patricia;Carlson, David A;Salazar Schettino, Paz María;Mijailovsky, Sergio;Rojas, Gloria;
Memórias do Instituto Oswaldo Cruz , 2002, DOI: 10.1590/S0074-02762002000600012
Abstract: capillary gas-liquid chromatography was used to analyse the cuticular hydrocarbons of three triatomine species, triatoma dimidiata, t. barberi and dipetalogaster maxima, domestic vectors of chagas disease in mexico. mixtures of saturated hydrocarbons of straight and methyl-branched chains were characteristic of the three species, but quantitatively different. major methylbranched components mostly corresponded to different saturated isomers of monomethyl, dimethyl and trimethyl branched hydrocarbons ranging from 29 to 39 carbon backbones. sex-dependant, quantitative differences in certain hydrocarbons were apparent in t. dimidiata.
Cuticular hydrocarbons of Chagas disease vectors in Mexico
Juárez M Patricia,Carlson David A,Salazar Schettino Paz María,Mijailovsky Sergio
Memórias do Instituto Oswaldo Cruz , 2002,
Abstract: Capillary gas-liquid chromatography was used to analyse the cuticular hydrocarbons of three triatomine species, Triatoma dimidiata, T. barberi and Dipetalogaster maxima, domestic vectors of Chagas disease in Mexico. Mixtures of saturated hydrocarbons of straight and methyl-branched chains were characteristic of the three species, but quantitatively different. Major methylbranched components mostly corresponded to different saturated isomers of monomethyl, dimethyl and trimethyl branched hydrocarbons ranging from 29 to 39 carbon backbones. Sex-dependant, quantitative differences in certain hydrocarbons were apparent in T. dimidiata.
Phospholipase D promotes Arcanobacterium haemolyticum adhesion via lipid raft remodeling and host cell death following bacterial invasion
Erynn A Lucas, Stephen J Billington, Petteri Carlson, David J McGee, B Helen Jost
BMC Microbiology , 2010, DOI: 10.1186/1471-2180-10-270
Abstract: Recombinant PLD rearranged HeLa cell lipid rafts in a dose-dependent manner and this was inhibited by cholesterol sequestration. PLD also promoted host cell adhesion, as a pld mutant had a 60.3% reduction in its ability to adhere to HeLa cells as compared to the wild type. Conversely, the pld mutant appeared to invade HeLa cells approximately two-fold more efficiently as the wild type. This finding was attributable to a significant loss of host cell viability following secretion of PLD from intracellular bacteria. As determined by viability assay, only 15.6% and 82.3% of HeLa cells remained viable following invasion by the wild type or pld mutant, respectively, as compared to untreated HeLa cells. Transmission electron microscopy of HeLa cells inoculated with A. haemolyticum strains revealed that the pld mutant was contained within intracellular vacuoles, as compared to the wild type, which escaped the vacuole. Wild type-infected HeLa cells also displayed the hallmarks of necrosis. Similarly inoculated HeLa cells displayed no signs of apoptosis, as measured by induction of caspase 3/7, 8 or 9 activities.These data indicate that PLD enhances bacterial adhesion and promotes host cell necrosis following invasion, and therefore, may be important in the disease pathogenesis of A. haemolyticum infections.Arcanobacterium haemolyticum is a gram positive, non-motile rod originally identified as a cause of pharyngitis and wound infections in U.S. servicemen and Pacific islanders [1,2]. A. haemolyticum is almost exclusively a human pathogen, making it somewhat unique within the genus [3]. The other species are uncommonly isolated, with the exception of Arcanobacterium pyogenes, which is an economically important opportunistic pathogen of livestock [3].A. haemolyticum pharyngitis is a disease of adolescents and young adults, with >90% of cases occurring in patients between 10-30 years of age [4-6]. Clinically, A. haemolyticum pharyngitis resembles that caused by Streptococcus p
Subjective health legacy of the Chornobyl accident: a comparative study of 19-year olds in Kyiv
Evelyn J Bromet, David P Taormina, Lin T Guey, Joost A Bijlsma, Semyon F Gluzman, Johan M Havenaar, Harold Carlson, Gabrielle A Carlson
BMC Public Health , 2009, DOI: 10.1186/1471-2458-9-417
Abstract: We assessed three groups of 19-year olds in Kyiv: 262 evacuees from contaminated areas near the plant; 261 classmate controls; and 325 population-based controls. The evacuees and classmates were previously assessed at age 11. Structured interviews were conducted with the adolescents and their mothers (N = 766), followed by general physical examinations (N = 722) and blood tests (N = 707). Proportional odds logistic regression and multi-group path analysis were the major statistical tests.The examination and blood test results were similar across groups except for a significantly elevated rate of thyroid enlargement found by palpation in evacuees (17.8%) compared former classmates (8.7%) and population-based controls (8.0%). In addition, four evacuees and one population control had had a thyroidectomy. Compared to controls, the evacuees rated their health the least positively and reported more medically diagnosed illnesses during the 5 years preceding the interview, particularly thyroid disease, migraine headache, and vascular dystony. The consistent risk factors (p < 0.001) for these subjective health reports were evacuee status, female gender, multiple hospitalizations, and health risk perception regarding Chornobyl. All three groups of mothers rated their children's health more negatively than the adolescents themselves, and maternal ratings were uniquely associated with the adolescents' health reports in the adjusted models. In the longitudinal evacuee and classmate subsamples, path analysis showed that mothers' health ratings when the children were age 11 predicted their later evaluations which in turn were associated with the adolescent self-reports.The more negative self-evaluations of the evacuees were linked to a number of risk factors, including multiple hospitalizations, health risk perceptions, and epidemiologic risk factors. The increased rate of thyroid cancer and other diagnoses no doubt contributed to the evacuees' less positive subjective health. The
Hegel and the Becoming of Essence
David Gray Carlson
Cosmos and History : the Journal of Natural and Social Philosophy , 2007,
Abstract: One of the more mysterious transitions in Hegelrsquo;s mnoumental lsquo;Science of Logicrsquo; is the transition from the last stages of Being into the shadowy negative realm of Essence. This paper assesses the logic of those steps, in which measure becomes fully present but unable to capture an absence Hegel will eventually name as Essence. The paper emphasizes that the correlativity that marks the realm of essence is already introduced in the final two chapters of Hegelrsquo;s analysis of measure. It concludes by explaining why Hegel thought bad astronomymdash;the division of planetary orbit into centripetal and centrifucal forcemdash;illustrates the final sublation of quality and quantity. While quality and quantity both have lsquo;beyondsrsquo;, the realm of essence does not. Essence is revealed to be a totality that contains both itself and other (measure, or appearance)nbsp; in a single correlation.
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