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Search Results: 1 - 10 of 173940 matches for " Gilbert Gregory E "
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Fitting parametric random effects models in very large data sets with application to VHA national data
Gebregziabher Mulugeta,Egede Leonard,Gilbert Gregory E,Hunt Kelly
BMC Medical Research Methodology , 2012, DOI: 10.1186/1471-2288-12-163
Abstract: Background With the current focus on personalized medicine, patient/subject level inference is often of key interest in translational research. As a result, random effects models (REM) are becoming popular for patient level inference. However, for very large data sets that are characterized by large sample size, it can be difficult to fit REM using commonly available statistical software such as SAS since they require inordinate amounts of computer time and memory allocations beyond what are available preventing model convergence. For example, in a retrospective cohort study of over 800,000 Veterans with type 2 diabetes with longitudinal data over 5 years, fitting REM via generalized linear mixed modeling using currently available standard procedures in SAS (e.g. PROC GLIMMIX) was very difficult and same problems exist in Stata’s gllamm or R’s lme packages. Thus, this study proposes and assesses the performance of a meta regression approach and makes comparison with methods based on sampling of the full data. Data We use both simulated and real data from a national cohort of Veterans with type 2 diabetes (n=890,394) which was created by linking multiple patient and administrative files resulting in a cohort with longitudinal data collected over 5 years. Methods and results The outcome of interest was mean annual HbA1c measured over a 5 years period. Using this outcome, we compared parameter estimates from the proposed random effects meta regression (REMR) with estimates based on simple random sampling and VISN (Veterans Integrated Service Networks) based stratified sampling of the full data. Our results indicate that REMR provides parameter estimates that are less likely to be biased with tighter confidence intervals when the VISN level estimates are homogenous. Conclusion When the interest is to fit REM in repeated measures data with very large sample size, REMR can be used as a good alternative. It leads to reasonable inference for both Gaussian and non-Gaussian responses if parameter estimates are homogeneous across VISNs.
Using quantile regression to investigate racial disparities in medication non-adherence
Mulugeta Gebregziabher, Cheryl P Lynch, Martina Mueller, Gregory E Gilbert, Carrae Echols, Yumin Zhao, Leonard E Egede
BMC Medical Research Methodology , 2011, DOI: 10.1186/1471-2288-11-88
Abstract: A retrospective cohort of 11,272 veterans with type 2 diabetes was assembled from Veterans Administration datasets from April 1996 to May 2006. The main outcome measure was MPR with quantile cutoffs Q1-Q4 taking values of 0.4, 0.6, 0.8 and 0.9. Quantile-regression (QReg) was used to model the association between MPR and race/ethnicity after adjusting for covariates. Comparison was made with commonly used ordinary-least-squares (OLS) and generalized linear mixed models (GLMM).Quantile-regression showed that Non-Hispanic-Black (NHB) had statistically significantly lower MPR compared to Non-Hispanic-White (NHW) holding all other variables constant across all quantiles with estimates and p-values given as -3.4% (p = 0.11), -5.4% (p = 0.01), -3.1% (p = 0.001), and -2.00% (p = 0.001) for Q1 to Q4, respectively. Other racial/ethnic groups had lower adherence than NHW only in the lowest quantile (Q1) of about -6.3% (p = 0.003). In contrast, OLS and GLMM only showed differences in mean MPR between NHB and NHW while the mean MPR difference between other racial groups and NHW was not significant.Quantile regression is recommended for analysis of data that are heterogeneous such that the tails and the central location of the conditional distributions vary differently with the covariates. QReg provides a comprehensive view of the relationships between independent and dependent variables (i.e. not just centrally but also in the tails of the conditional distribution of the dependent variable). Indeed, without performing QReg at different quantiles, an investigator would have no way of assessing whether a difference in these relationships might exist.Diabetes is a chronic debilitating illness that affects approximately 24 million people in the United States [1]. Medication adherence is an important component of good diabetes care and medication non-adherence is associated with poor glycemic control [2,3], increased health utilization [4,5], increased health care costs [6,7], and in
Dissipation of Energy Radiated by Earthquakes
E. GILBERT,R. BULAND
Annals of Geophysics , 1977, DOI: 10.4401/ag-4833
Abstract: SUMMARY. - Representing radiated seismic energy as a sum of normal modes we are able to develop approximate equations describing the dissipation of this energy in the earth by solid friction. In particular we calculate total energy radiated and spherically averaged dissipation as a function of depth. In a sample (long period) model study we find that energy density as a function of radius and frequency have simple forms and smooth variations with source depth and mechanism as long as the event's spectrum is dominated by fundamental mode energy. Further, we find that shallow focus events are an order of magnitude more energetic than deeper events for the same moment and that dip slip events are up to a factor of six more energetic than strike slip events for the same moment and depth.
Educación formal de los padres y aptitudes de sus hijos
Otto E. Gilbert
Revista Latinoamericana de Psicología , 1996,
Abstract: Aumentan las aptitudes de los hijos conforme aumentan los a os de educación formal que recibieron sus padres? Para dar respuesta a esta pregunta se recabó la información personal y familiar por medio de un cuestionario el cual se aplicó a estudiantes que en 1993 asistieron al tercer a os del ciclo básico y también a los que asistieron al último a o del ciclo diversificado en institutos nacionales de toda las república de Guatemala. Se midieron sus aptitudes en seis diferentes tests. La muestra total de 6.427 estudiantes se dividió en ocho grupos de acuerdo al a o de estudios que cursaban, a su género (sexo) y al lugar de residencia. Se calcularon correlaciones, para cada uno de los ocho grupos, entre cada una de las aptitudes y la suma total de a os de educación formal cursados por ambos padres, por solo la madre y por solo el padre. En siete de los ocho grupos se encontraron coeficientes de correlación positi vos y significativos entre estas variables de educación de los padres y las aptitudes de sus hijos. Los resultados sugieren una respuesta afrrmativa a la pregunta planeada.
The Effect of Food Images on Mood and Arousal Depends on Dietary Histories and the Fat and Sugar Content of Foods Depicted  [PDF]
Gregory J. Privitera, Danielle E. Antonelli, Heather E. Creary
Journal of Behavioral and Brain Science (JBBS) , 2013, DOI: 10.4236/jbbs.2013.31001
Abstract:

Background: While brain imaging studies show that reward regions in the human brain that regulate reward-guided behavior and integrate sensory modalities of smell, taste, and texture respond preferentially to high calorie foods, few studies account for dietary histories or account for recent behavioral evidence showing preferential responding for fruits (a low calorie food that tastes sweet). To address these concerns, the present study tested the hypothesis that images of high/low fat and sugar foods, even sugary foods that are low calorie (i.e., fruits), will enhance emotional responsiveness and that these changes may be related to dietary histories with fat and sugar intake. Method: Participants were shown 4 sets of 15 food images with each food image automatically timed every 9 s to transition to a new food image; participant pre-post mood and arousal was measured. The 4 sets of food images were high fat-high sugar (HFHS; desserts), high fat-low sugar (HFLS; fried foods), low fat-high sugar (LFHS; fruits), or low fat-low sugar (LFLS; vegetables) foods. To account for dietary histories, participants also completed estimated daily intake scales (EDIS) for sugar and fat. Results: Mood and arousal significantly increased in all groups, except Group LFLS, and even in a group that was low calorie but shown foods that taste sweet, i.e., Group LFHS. Interestingly, changes in arousal, but not mood, were dependent on participant histories with sugar and fat intake. Conclusion: Changes in emotional responsiveness to food images were nutrient-specific, which can be a more detailed level of analysis for assessing responsiveness to food images. Also, participant histories with sugar and fat should be taken into account as these histories can explain the changes in arousal observed here.

Analog insulin detemir for patients with type 1 and type 2 diabetes: a review
Gregory E Peterson
Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy , 2009, DOI: http://dx.doi.org/10.2147/DMSO.S3401
Abstract: nalog insulin detemir for patients with type 1 and type 2 diabetes: a review Review (5307) Total Article Views Authors: Gregory E Peterson Published Date May 2009 Volume 2009:2 Pages 31 - 36 DOI: http://dx.doi.org/10.2147/DMSO.S3401 Gregory E Peterson Department of Internal Medicine, Des Moines University, USA Objective: To review insulin detemir for clinical use to better manage patients with type 1 and type 2 diabetes. Methods: A MEDLINE search, in English, from June 30, 2006 to December 1, 2008, using the terms “insulin analogs,” “insulin detemir” and “long-acting insulin analog.” Results: Insulin detemir improves glycemic control, based on HbA1C reduction and fasting glucose levels, without increasing the risk of hypoglycemia and weight gain. Insulin detemir has lower glycemic variability, with less intra-subject variability in blood glucose levels in patients with type 1 and type 2 diabetes, without increasing the risk of hypoglycemia. When added to oral anti-diabetes agents (OADs) in type 2 diabetes, insulin detemir demonstrates superiority to other basal insulin options. Conclusion: Insulin detemir appears to provide better glycemic control with a lower risk of hypoglycemia and less weight gain in the treatment of patients with type 1 and type 2 diabetes.
THE SPANISH MOOD/SUBORDINATION/REFERENCE INTERFACE
Amy E. Gregory
International Journal of English Studies (IJES) , 2007, DOI: 10.6018/ijes.7.1.48861
Abstract: This study deals with the discourse function of the Spanish subjunctive mood. Traditional approaches focus on its semantics, invoking the notions of volition, doubt, negation, and emotion while maintaining the importance of the clause's subordinate status and change of subject from matrix verb to subordinate verb. Notwithstanding, thirty years of linguistic research on the Spanish mood contrast have given rise to the descriptors ± assertion: indicative is +assertive while subjunctive is -assertive. Although these descriptors are appropriate, viewing the subjunctive mood as a discourse cohesive device makes apparent the true nature of the mood contrast. Anaphoric, exophoric, and cataphoric features of languages refer to antecedents, elements of the physical context, or foreshadowed events/information, respectively. This article proposes a mechanism by which Spanish subjunctive clauses fulfill all three functions, circumscribing the Spanish mood contrast within the language's deictic system, and suggests avenues for future research.
Analog insulin detemir for patients with type 1 and type 2 diabetes: a review
Gregory E Peterson
Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy , 2009,
Abstract: Gregory E PetersonDepartment of Internal Medicine, Des Moines University, USAObjective: To review insulin detemir for clinical use to better manage patients with type 1 and type 2 diabetes.Methods: A MEDLINE search, in English, from June 30, 2006 to December 1, 2008, using the terms “insulin analogs,” “insulin detemir” and “long-acting insulin analog.”Results: Insulin detemir improves glycemic control, based on HbA1C reduction and fasting glucose levels, without increasing the risk of hypoglycemia and weight gain. Insulin detemir has lower glycemic variability, with less intra-subject variability in blood glucose levels in patients with type 1 and type 2 diabetes, without increasing the risk of hypoglycemia. When added to oral anti-diabetes agents (OADs) in type 2 diabetes, insulin detemir demonstrates superiority to other basal insulin options.Conclusion: Insulin detemir appears to provide better glycemic control with a lower risk of hypoglycemia and less weight gain in the treatment of patients with type 1 and type 2 diabetes.Keywords: type 1 diabetes, type 2 diabetes, insulin analogs, insulin detemir
Modeling Time in Medical Education Research: The Potential of New Flexible Parametric Methods of Survival Analysis  [PDF]
Gilbert Reibnegger
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.326139
Abstract: Time – the duration of a certain process or the timing of a specified event – plays a central role in many situations in medical research. Waiting time analysis (“survival analysis”) is a field of statistics providing the tools for solving the unique problems of such studies. In particular, waiting time analysis correctly handles the typical positively skewed distributions of waiting times as well as censored observations on study subjects for whom the target event does not occur before data collection ends. For decades, non-parametric Kaplan-Meier analysis and semiparametric Cox regression despite some inherent limitations have dominated waiting time analysis in medical contexts, while parametric models, although in principle offering important theoretical advantages, were scarcely applied in practice because of lacking flexibility. Recently, however, new flexible parametric methods (Royston-Parmar models) became available offering exciting new research potential. Surprisingly, although medical education research deals with a range of typical problems suited for waiting time analysis, the methods were rarely used in the past. By re-analyzing data from a previous investigation on study dropout of medical students, this is the first study demonstrating the usefulness and practical applications of waiting time analysis with special emphasis on Royston-Parmar models in a medical education research environment.
The Canadian Policy on the Protection of Foreign Investment and the Canada-China Bilateral Investment Treaty  [PDF]
Gilbert Gagné
Beijing Law Review (BLR) , 2019, DOI: 10.4236/blr.2019.103021
Abstract: For a trading nation such as Canada, access to foreign markets has long been a key concern. In 2012, the Canadian government concluded a bilateral investment treaty (BIT) with China, so as to better protect Canada’s investments in this big expanding market. China’s communist regime, coupled with the importance of the country, has seemingly caused the Canada-China BIT to differ from the Canadian BIT model, both in terms of substantive provisions and the investor-state dispute settlement mechanism. Drawing on a legal-political analytical approach, the article: 1) looks at some key provisions on investment protection in the Canada-China BIT and 2) discusses the ways in which this BIT marks a departure in Canadian foreign investment policy. It also considers disagreements among legal scholars and commentators as to the implications of these differences, particularly with respect to the non-reciprocal character of the BIT to China’s advantage.
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