879 resultados para Group effect


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A novel DBU-promoted ring transformation of substituted isoxazoles to substituted pyrroles is described

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Leaf-cutting ant workers dig underground chambers, for housing their symbiotic fungus, interconnected by a vast quantity of tunnels whose function is to permit the entrance of food (leaves), gaseous exchanges, andmovement of workers, offspring, and the queen. Digging is a task executed by a group of workers, but little is known about the group effect and group-constructed functional structures. Thus, we analyzed the structures formed by worker groups (5, 10, 20, and 40 individuals) of the leaf-cutting ant, Atta sexdens rubropilosa, for 2 days of excavation. The digging arena was the same for the 4 groups, with each group corresponding to a different density. Our results verified a pattern of tunneling by the workers, but no chamber was constructed. The group effect is well known, since the 40-worker group dug significantly more than the groups of 5, 10, and 20. These groups did not differ statistically from each other. Analysis of load/worker verified that workers of the smallest group carried the greatest load. Our paper demonstrates the group effect on the digging of nests, namely, that excavation is proportional to group size, but without emergence of a functional structure such as a chamber.

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The use of group-randomized trials is particularly widespread in the evaluation of health care, educational, and screening strategies. Group-randomized trials represent a subset of a larger class of designs often labeled nested, hierarchical, or multilevel and are characterized by the randomization of intact social units or groups, rather than individuals. The application of random effects models to group-randomized trials requires the specification of fixed and random components of the model. The underlying assumption is usually that these random components are normally distributed. This research is intended to determine if the Type I error rate and power are affected when the assumption of normality for the random component representing the group effect is violated. ^ In this study, simulated data are used to examine the Type I error rate, power, bias and mean squared error of the estimates of the fixed effect and the observed intraclass correlation coefficient (ICC) when the random component representing the group effect possess distributions with non-normal characteristics, such as heavy tails or severe skewness. The simulated data are generated with various characteristics (e.g. number of schools per condition, number of students per school, and several within school ICCs) observed in most small, school-based, group-randomized trials. The analysis is carried out using SAS PROC MIXED, Version 6.12, with random effects specified in a random statement and restricted maximum likelihood (REML) estimation specified. The results from the non-normally distributed data are compared to the results obtained from the analysis of data with similar design characteristics but normally distributed random effects. ^ The results suggest that the violation of the normality assumption for the group component by a skewed or heavy-tailed distribution does not appear to influence the estimation of the fixed effect, Type I error, and power. Negative biases were detected when estimating the sample ICC and dramatically increased in magnitude as the true ICC increased. These biases were not as pronounced when the true ICC was within the range observed in most group-randomized trials (i.e. 0.00 to 0.05). The normally distributed group effect also resulted in bias ICC estimates when the true ICC was greater than 0.05. However, this may be a result of higher correlation within the data. ^

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Hierarchical linear growth model (HLGM), as a flexible and powerful analytic method, has played an increased important role in psychology, public health and medical sciences in recent decades. Mostly, researchers who conduct HLGM are interested in the treatment effect on individual trajectories, which can be indicated by the cross-level interaction effects. However, the statistical hypothesis test for the effect of cross-level interaction in HLGM only show us whether there is a significant group difference in the average rate of change, rate of acceleration or higher polynomial effect; it fails to convey information about the magnitude of the difference between the group trajectories at specific time point. Thus, reporting and interpreting effect sizes have been increased emphases in HLGM in recent years, due to the limitations and increased criticisms for statistical hypothesis testing. However, most researchers fail to report these model-implied effect sizes for group trajectories comparison and their corresponding confidence intervals in HLGM analysis, since lack of appropriate and standard functions to estimate effect sizes associated with the model-implied difference between grouping trajectories in HLGM, and also lack of computing packages in the popular statistical software to automatically calculate them. ^ The present project is the first to establish the appropriate computing functions to assess the standard difference between grouping trajectories in HLGM. We proposed the two functions to estimate effect sizes on model-based grouping trajectories difference at specific time, we also suggested the robust effect sizes to reduce the bias of estimated effect sizes. Then, we applied the proposed functions to estimate the population effect sizes (d ) and robust effect sizes (du) on the cross-level interaction in HLGM by using the three simulated datasets, and also we compared the three methods of constructing confidence intervals around d and du recommended the best one for application. At the end, we constructed 95% confidence intervals with the suitable method for the effect sizes what we obtained with the three simulated datasets. ^ The effect sizes between grouping trajectories for the three simulated longitudinal datasets indicated that even though the statistical hypothesis test shows no significant difference between grouping trajectories, effect sizes between these grouping trajectories can still be large at some time points. Therefore, effect sizes between grouping trajectories in HLGM analysis provide us additional and meaningful information to assess group effect on individual trajectories. In addition, we also compared the three methods to construct 95% confident intervals around corresponding effect sizes in this project, which handled with the uncertainty of effect sizes to population parameter. We suggested the noncentral t-distribution based method when the assumptions held, and the bootstrap bias-corrected and accelerated method when the assumptions are not met.^

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Objective: To determine if systematic variation of diagnostic terminology (i.e. concussion, minor head injury [MHI], mild traumatic brain injury [mTBI]) following a standardized injury description produced different expected symptoms and illness perceptions. We hypothesized that worse outcomes would be expected of mTBI, compared to other diagnoses, and that MHI would be perceived as worse than concussion. Method:108 volunteers were randomly allocated to conditions in which they read a vignette describing a motor vehicle accident-related mTBI followed by: a diagnosis of mTBI (n=27), MHI (n=24), concussion (n=31); or, no diagnosis (n=26). All groups rated: a) event ‘undesirability’; b) illness perception, and; c) expected Postconcussion Syndrome (PCS) and Posttraumatic Stress Disorder (PTSD) symptoms six months post injury. Results: On average, more PCS symptomatology was expected following mTBI compared to other diagnoses, but this difference was not statistically significant. There was a statistically significant group effect on undesirability (mTBI>concussion & MHI), PTSD symptomatology (mTBI & no diagnosis>concussion), and negative illness perception (mTBI & no diagnosis>concussion). Conclusion: In general, diagnostic terminology did not affect anticipated PCS symptoms six months post injury, but other outcomes were affected. Given that these diagnostic terms are used interchangeably, this study suggests that changing terminology can influence known contributors to poor mTBI outcome.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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OBJECTIVE: To evaluate a healthy lifestyle intervention to reduce adiposity in children aged 5 to 9 years and assess whether adding parenting skills training would enhance this effect. PARTICIPANTS AND METHODS: We conducted a single-blinded randomized controlled trial of prepubertal moderately obese (International Obesity Task Force cut points) children, aged 5 to 9 years. The 6-month program targeted parents as the agents of change for implementing family lifestyle changes. Only parents attended group sessions. We measured BMI and waist z scores and parenting constructs at baseline, 6, 12, 18, 24 months. RESULTS: Participants (n = 169; 56% girls) were randomized to a parenting skills plus healthy lifestyle group (n = 85) or a healthy lifestyle–only group (n = 84). At final 24-month assessment 52 and 54 children remained in the parenting skills plus healthy lifestyle and the healthy lifestyle–only groups respectively. There were reductions (P < .001) in BMI z score (0.26 [95% confidence interval: 0.22–0.30]) and waist z score (0.33 [95% confidence interval: 0.26–0.40]). There was a 10% reduction in z scores from baseline to 6 months that was maintained to 24 months with no additional intervention. Overall, there was no significant group effect. A similar pattern of initial improvement followed by stability was observed for parenting outcomes and no group effect. CONCLUSIONS: Using approaches that specifically target parent behavior, relative weight loss of ∼10% is achievable in moderately obese prepubertal children and can be maintained for 2 years from baseline. These results justify an investment in treatment as an effective secondary obesity-prevention strategy.

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The aim of the study was to determine how aspects of communication between nurses and the elderly were perceived by elderly people, future nurses, and uninvolved observers. Respondents (elderly women and nursing and psychology students) rated videotapes of interactions between a nurse and an elderly woman on three dimensions: patronizing, status, and solidarity. Three communication strategies and their combinations were represented in the vignettes. Because the strategies presented were perceived as patronizing by all three groups, no group effect was found for the patronizing dimension. The results show clear group differences particularly between the nursing students and the elderly, with the elderly rating many of the strategies more positively than did the nursing students. The results are discussed in relation to previous evaluations of overaccommodation, and implications of the different perceptions are considered.

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Objective - Report long term outcomes of the NOURISH randomized controlled trial (RCT) that evaluated a universal intervention commencing in infancy to provide anticipatory guidance to first-time mothers on ‘protective’ complementary feeding practices which were hypothesized to reduce childhood obesity risk. Subjects and Methods - The NOURISH RCT enrolled 698 mothers (mean age 30.1 years, SD=5.3) with healthy term infants (51% female). Mothers were randomly allocated to usual care or to attend two 6-session, 12-week group education modules. Outcomes were assessed five times: baseline (infants 4.3 months); 6 months after module 1 (infants 14 months); 6 months after module 2 (infants 2 years) and at 3.5 and 5 years of age. Maternal feeding practices were self-reported using validated questionnaires. BMI Z-score was calculated from measured child height and weight. Linear Mixed Models evaluated intervention (group) effect across time. Results - Retention at 5 years of age was 61%. Across ages 2-5 years, intervention mothers reported less frequent use of non-responsive feeding practices on 6/9 scales. At 5 years they also reported more appropriate responses to food refusal on 7/12 items (Ps ≤.05). No statistically significant group effect was noted for anthropometric outcomes (BMI Z-score: P=.06), or the prevalence of overweight/obesity (control 13.3% vs. intervention 11.4%, P=.66). Conclusions - Anticipatory guidance on complementary feeding resulted in first-time mothers reporting increased use of protective feeding practices. These intervention effects were sustained up to five years of age and were paralleled by a non-significant trend for lower child BMI Z-scores at all post-intervention assessment points.

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O efeito de instalação de estacas cravadas em areia, que promove um aumento da compacidade do solo e de seus parâmetros de resistência e deformabilidade, é analisado nesta dissertação em conjunto com o efeito de grupo. O procedimento estabelecido objetiva quantificar a melhoria após a instalação de um grupo de estacas e foi desenvolvido nesta pesquisa a partir da contribuição de Alves (1998). Para a utilização deste procedimento, foram propostas correlações do módulo de Young do solo em função da resistência à penetração NSPT (ou da resistência à penetração normalizada N60), a partir de um banco de dados obtido da literatura, visando não apenas as aplicações implementadas neste estudo, como também nortear futuras aplicações práticas. Na análise de casos documentados da literatura, foi utilizado o programa Plaxis 3D Foundation. Inicialmente foi procedida a calibração do programa através da reprodução de um caso de instrumentação de um grupo de estacas na argila rija de Londres, muito bem documentado por Cooke et al. (1980). Os resultados das simulações, com parâmetros do solo obtidos da literatura, se ajustaram muito bem aos resultados experimentais, seja nos valores de recalque, seja nos diagramas de transferência de carga. Posteriormente, a melhoria do solo por efeito da instalação foi estimada, através do procedimento estabelecido nesta dissertação, baseado em Alves (1998), a partir das características iniciais do solo antes da instalação de um grupo de estacas em modelo reduzido em solo arenoso. Obtidos os parâmetros melhorados previstos para o solo após a instalação, estes foram aplicados a um grupo de 9 estacas, para diferentes espaçamentos relativos, como dados de entrada no programa Plaxis. A comparação dos resultados experimentais com aqueles simulados numericamente sinaliza para o potencial tanto do programa Plaxis, na reprodução do comportamento do conjunto, como do modelo de Alves (1998), que norteou o procedimento proposto nesta pesquisa. O fator de escala, ressaltado na dissertação, bem como outros aspectos relevantes observados nas análises realizadas, são propostos como temas futuros a serem investigados na continuidade desta linha de pesquisa.

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We recently generated a knock-in mouse model (PYGM p.R50X/p.R50X) of McArdle disease (myophosphorylase deficiency). One mechanistic approach to unveil the molecular alterations caused by myophosphorylase deficiency, which is arguably the paradigm of 'exercise intolerance', is to compare the skeletal-muscle tissue of McArdle, heterozygous, and healthy (wild type (wt)) mice. We analyzed in quadriceps muscle of p.R50X/p.R50X (n=4), p.R50X/wt (n=6) and wt/wt mice (n=5) (all male, 8 wk-old) molecular markers of energy-sensing pathways, oxidative phosphorylation (OXPHOS) and autophagy/proteasome systems, oxidative damage and sarcoplamic reticulum (SR) Ca handling. We found a significant group effect for total AMPK (tAMPK) and ratio of phosphorylated (pAMPK)/tAMPK (P=0.012 and 0.033), with higher mean values in p.R50X/p.R50X mice vs. the other two groups. The absence of massive accumulation of ubiquitinated proteins, autophagosomes or lysosomes in p.R50X/p.R50X mice suggested no major alterations in autophagy/proteasome systems. Citrate synthase activity was lower in p.R50X/p.R50X mice vs. the other two groups (P=0.036) but no statistical effect existed for respiratory chain complexes. We found higher levels of 4-hydroxy-2-nonenal-modified proteins in p.R50X/p.R50X and p.R50X/wt mice compared with the wt/wt group (P=0.011). Sarco(endo)plasmic reticulum ATPase 1 (SERCA1) levels detected at 110kDa tended to be higher in p.R50X/p.R50X and p.R50X/wt mice compared with wt/wt animals (P=0.076), but their enzyme activity was normal. We also found an accumulation of phosphorylated SERCA1 in p.R50X/p.R50X animals. Myophosphorylase deficiency causes alterations in sensory energetic pathways together with some evidence of oxidative damage and alterations in Ca handling but with no major alterations in OXPHOS capacity or autophagy/ubiquitination pathways, which suggests that the muscle tissue of patients is likely to adapt overall favorably to exercise training interventions.

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Autism and Asperger's disorder (AD) are neurodevelopmental conditions that affect cognitive and social-communicative function. Using a movement-related potential (MRP) paradigm, we investigated the clinical and neurobiological issue of 'disorder separateness' versus 'disorder variance' in autism and AD. This paradigm has been used to assess basal ganglia/supplementary motor functioning in Parkinson's disease. Three groups (high functioning autism [HFA]: 16 males, 1 female; mean age 12y 5mo [SD 4y 4mo]; AD: 11 males, 2 females; mean age 13y 5mo [SD 3y 8mo]; comparison group: 13 males, 8 females; mean age 13y 10mo, [SD 3y 11 mo]) completed a cued motor task during electroencephalogram recording of MRPs. The HFA group showed reduced peak amplitude at Cz, indicating less activity over the supplementary motor area during movement preparation. Although an overall significant between-group effect was found for early slope and peak amplitude, subanalysis revealed that the group with AD did not differ significantly from either group. However, it is suggested that autism and AD may be dissociated on the basis of brain-behaviour correlations of IQ with specific neurobiological measures. The overlap between MRP traces for autism and Parkinson's disease suggests that the neurobiological wiring of motor functioning in autism may bypass the supplementary motor area/primary motor cortex pathway.

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Objectives: To evaluate the feasibility of a randomized-controlled trial (RCT) investigating the effects of adding auricular acupuncture (AA) to exercise for participants with chronic low-back pain (CLBP). Methods: Participants with CLBP were recruited from primary care and a university population and were randomly allocated (n=51) to 1 of 2 groups: (1) "Exercise Alone (E)"-12-week program consisting of 6 weeks of supervised exercise followed by 6 weeks unsupervised exercise (n=27); or (2) "Exercise and AA (EAA)"-12-week exercise program and AA (n=24). Outcome measures were recorded at baseline, week 8, week 13, and 6 months. The primary outcome measure was the Oswestry Disability Questionnaire. Results: Participants in the EAA group demonstrated a greater mean improvement of 10.7% points (95% confidence interval, -15.3,-5.7) (effect size=1.20) in the Oswestry Disability Questionnaire at 6 months compared with 6.7% points (95% confidence interval, -11.4,-1.9) in the E group (effect size=0.58). There was also a trend towards a greater mean improvement in quality of life, LBP intensity and bothersomeness, and fear-avoidance beliefs in the EAA group. The dropout rate for this trial was lower than anticipated (15% at 6 mo), adherence with exercise was similar (72% E; 65% EAA). Adverse effects for AA ranged from 1% to 14% of participants. Discussion: Findings of this study showed that a main RCT is feasible and that 56 participants per group would need to be recruited, using multiple recruitment approaches. AA was safe and demonstrated additional benefits when combined with exercise for people with CLBP, which requires confirmation in a fully powered RCT.

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Effectiveness of brief/minimal contact self-activation interventions that encourage participation in physical activity (PA) for chronic low back pain (CLBP >12 weeks) is unproven. The primary objective of this assessor-blinded randomized controlled trial was to investigate the difference between an individualized walking programme (WP), group exercise class (EC), and usual physiotherapy (UP, control) in mean change in functional disability at 6 months. A sample of 246 participants with CLBP aged 18 to 65 years (79 men and 167 women; mean age ± SD: 45.4 ± 11.4 years) were recruited from 5 outpatient physiotherapy departments in Dublin, Ireland. Consenting participants completed self-report measures of functional disability, pain, quality of life, psychosocial beliefs, and PA were randomly allocated to the WP (n = 82), EC (n = 83), or UP (n = 81) and followed up at 3 (81%; n = 200), 6 (80.1%; n = 197), and 12 months (76.4%; n = 188). Cost diaries were completed at all follow-ups. An intention-to-treat analysis using a mixed between-within repeated-measures analysis of covariance found significant improvements over time on the Oswestry Disability Index (Primary Outcome), the Numerical Rating Scale, Fear Avoidance-PA scale, and the EuroQol EQ-5D-3L Weighted Health Index (P < 0.05), but no significant between-group differences and small between-group effect sizes (WP: mean difference at 6 months, 6.89 Oswestry Disability Index points, 95% confidence interval [CI] -3.64 to -10.15; EC: -5.91, CI: -2.68 to -9.15; UP: -5.09, CI: -1.93 to -8.24). The WP had the lowest mean costs and the highest level of adherence. Supervised walking provides an effective alternative to current forms of CLBP management.