834 resultados para controlling behaviors


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We demonstrate that a system obeying the complex Lorenz equations in the deep chaotic regime can be controlled to periodic behavior by applying a modulation to the pump parameter. For arbitrary modulation frequency and amplitude there is no obvious simplification of the dynamics. However, we find that there are numerous windows where the chaotic system has been controlled to different periodic behaviors. The widths of these windows in parameter space are narrow, and the positions are related to the ratio of the modulation frequency of the pump to the average pulsation frequency of the output variable. These results are in good agreement with observations previously made in a far-infrared laser system.

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OBJECTIVE: The objective of this study was to compare the frequency of risk behaviors and to measure the extent of co-occurrence of these behaviors in chronically ill and healthy adolescents. METHODS: Data were drawn from the 2002 Swiss Multicenter Adolescent Survey on Health database, a nationally representative survey of 7548 adolescents in postmandatory school aged 16 to 20 years. There were 760 subjects who reported a chronic illness and/or a disability. The comparison group consisted of 6493 subjects who answered negatively to both questions. We defined 8 risk behaviors: daily smoking, alcohol misuse, current cannabis use, current use of any other illegal drug, early sexual debut, eating disorder, violent acts, and antisocial acts. We analyzed each behavior and the sum of behaviors, controlling for age, gender, academic track, parents' education level, depression, and health status. Results are given as adjusted odds ratios using the comparison group as the reference category. RESULTS: Youth with a chronic condition were more likely to smoke daily, to be current cannabis users, and to have performed violent or antisocial acts. Youth with a chronic condition were also more likely to report 3 or >or=4 risk behaviors. CONCLUSIONS: These results indicate that having a chronic condition carries additional risks for engaging in health risk behaviors and emphasize the importance of health risk screening and preventive counseling for young people in general and among those suffering from chronic conditions in particular.

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Perceiving injustice is a key antecedent of a large range of undesirable employee attitudes and behaviors at work. For example, research has shown that employees who perceive their workplace as unfair are less satisfied, less committed and engage in more counterproductive behaviors. In this study, we suggest that justice motives like the belief in a just world (BJW) contribute to explaining relations between justice perceptions and undesirable behaviors. Specifically, we propose that individual differences in BJW (i.e, the belief that the world is just, where everyone is rewarded for his or her behavior) are related to work-related behaviors and attitudes by coloring perceptions of workplace fairness. We investigated our hypotheses in a survey study with 176 employees of various organizations (36% women; mean tenure 12.3 yeares). Results showed that after controlling for other influencing factors (e.g., neuroticism) BJW was negatively related to self-reported work deviant behaviors and to cynical, disillusioned attitudes toward the current job. Moreover, BJW was positively related to overall job satisfaction. Consistent with our expectations, relations of BJW with deviant behaviors and with attitudes were mediated by perceptions of interactional and procedural justice. These results suggest extending models of justice and deviance by including motives such as BJW.

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We report a phenomenon occurring in field-responsive suspensions: shear-induced anomalous stresses. Competition between a rotating field and a shear flow originates a multiplicity of anomalous stress behaviors in suspensions of bound dimers constituted by induced dipoles. The great variety of stress regimes includes nonmonotonic behaviors, multiresonances, negative viscosity effect, and blockades. The reversibility of the transitions between the different regimes and the self-similarity of the stresses make this phenomenon controllable and therefore applicable to modify macroscopic properties of soft condensed matter phases.

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The aim of this study was to determine whether high blood pressure (HBP) is associated with sedentary behavior in young people even after controlling for potential confounders (gender, age, socioeconomic level, tobacco, alcohol, obesity and physical activity). In this epidemiological study, 1231 adolescents were evaluated. Blood pressure was measured with an oscillometric device and waist circumference with an inextensible tape. Sedentary behavior (watching television, computer use and playing video games) and physical activity were assessed by a questionnaire. We used mean and standard deviation to describe the statistical analysis, and the association between HBP and sedentary behavior was assessed by the chi-squared test. Binary logistic regression was used to observe the magnitude of association and cluster analyses (sedentary behavior and abdominal obesity; sedentary behavior and physical inactivity). HBP was associated with sedentary behaviors [odds ratio (OR) = 2.21, 95% confidence interval (CI) = 1.41-3.96], even after controlling for various confounders (OR = 1.68, CI = 1.03-2.75). In cluster analysis the combination of sedentary behavior and elevated abdominal obesity contributed significantly to an increased likelihood of having HBP (OR = 13.51, CI 7.21-23.97). Sedentary behavior was associated with HBP, and excess fat in the abdominal region contributed to the modulation of this association.

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OBJECTIVE: Caring for a loved one with Alzheimer disease is a highly stressful experience that is associated with significant depressive symptoms. Previous studies indicate a positive association between problem behaviors in patients with Alzheimer disease (e.g., repeating questions, restlessness, and agitation) and depressive symptoms in their caregivers. Moreover, the extant literature indicates a robust negative relationship between escape-avoidance coping (i.e., avoiding people, wishing the situation would go away) and psychiatric well-being. The purpose of this study was to test a mediational model of the associations between patient problem behaviors, escape-avoidance coping, and depressive symptoms in Alzheimer caregivers. METHODS: Ninety-five spousal caregivers (mean age: 72 years) completed measures assessing their loved ones' frequency of problem behaviors, escape-avoidance coping, and depressive symptoms. A mediational model was tested to determine if escape-avoidant coping partially mediated the relationship between patient problem behaviors and caregiver depressive symptoms. RESULTS: Patient problem behaviors were positively associated with escape-avoidance coping (beta = 0.38, p < 0.01) and depressive symptoms (beta = 0.26, p < 0.05). Escape-avoidance coping was positively associated with depressive symptoms (beta = 0.33, p < 0.01). In a final regression analysis, the impact of problem behaviors on depressive symptoms was less after controlling for escape-avoidance coping. Sobel's test confirmed that escape-avoidance coping significantly mediated the relationship between problem behaviors and depressive symptoms (z = 2.07, p < 0.05). CONCLUSION: Escape-avoidance coping partially mediates the association between patient problem behaviors and depressive symptoms among elderly caregivers of spouses with dementia. This finding provides a specific target for psychosocial interventions for caregivers.

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This research is a secondary analysis of the Qué Sabrosa Vida population-based cross-sectional study of two predominately Mexican American communities located along the Texas-Mexico border in 2000. There were two aims for this research. The first was to determine the relationship between knowledge of exercise and water recommendations, and exercise behavior and water consumption. The second was to determine the relationship between exercise behavior and percentage of energy consumption from beverages. Chi-square analysis revealed the majority of both populations had adequate knowledge about water and exercise recommendations, although significant percentages of the populations (>40%) did not consume water or exercise in adequate amounts. Knowledge was found to be a component of both behaviors, as it was more prevalent in the adults who exercised and consumed water in adequate amounts. Analysis of variance revealed no significant difference between overall beverage calorie percentage and exercise level (all p-values > 0.05); both regions and genders reported ∼18% of total caloric intake from beverages. There was no disproportionate influence of beverage calories on total caloric intake, after controlling for water consumption and independent of exercise behavior. These findings suggest that overall caloric intake, from both foods and beverages, may be the most influential factor to the energy imbalance contributing to the obesity crisis in these Hispanic border populations. ^

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With rates of obesity and overweight continuing to increase in the US, the attention of public health researchers has focused on nutrition and physical activity behaviors. However, attempts to explain the disparate rates of obesity and overweight between whites and Hispanics have often proven inadequate. Indeed, the nebulous term ‘ethnicity’ provides little important detail in addressing potential biological, behavioral, and environmental factors that may affect rates of obesity and overweight. In response to this, the present research seeks to test the explanatory powers of ethnicity by situating the nutrition and physical activity behaviors of whites and Hispanic into their broader social contexts. It is hypothesized that a student's gender and grade level, as well as the socioeconomic status and ethnic composition of their school, will have more predictive power for these behaviors than will self-reported ethnicity. ^ Analyses revealed that while ethnicity did not seem to impact nutrition behaviors among the wealthier schools and those with fewer Hispanics, ethnicity was relevant in explaining these behaviors in the poorest tertile of schools and those with the highest number of Hispanics. With respect to physical activity behaviors, the results were mixed. The variables representing regular physical activity, participation in extracurricular physical activities, and performance of strengthening and toning exercises were more likely to be determined by SES and ethnic composition than ethnicity, especially among 8th grade males. However, school sports team and physical education participation continued to vary by ethnicity, even after controlling for SES and ethnic composition of schools. In conclusion then, it is important to understand the intersecting demographic and social variables that define and surround the individual in order to understand nutrition and physical activity behaviors and thus overweight and obesity.^

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Aim To examine the association between the crack cocaine cessation and risky sexual behaviors. Design and setting Between June 2002 and March 2005, a sample of African-American residents of Houston, Texas who were using crack at the time of enrollment participated in a cohort study to evaluate per outreach interventions to reduce HIV risk behaviors. The sample for this study consisted of 351 women and men who completed structured surveys at baseline and at six months about socio-demographic characteristics, drug use, and sexual behaviors. Multivariate logistic regression was used to analyze the association between crack cessation and risky sexual behaviors at follow-up, while controlling for confounding characteristics. Measurements Crack cessation was defined as reporting no crack use in the 30 days prior to the follow-up interview. Possible associated factors included unprotected sex, having multiple sex partners, trading sex for money/drugs, crack use, and socio-demographic variables. Findings At the six-month follow-up interview, 21% of participants reported that they had not used crack in the previous 30 days. For women, crack cessation was significantly associated with having only one sex partner at follow-up; for men, crack cessation was significantly associated with being single, separated, or divorced at baseline, having only one sex partner at follow-up, and initiating protected sex by follow-up. Conclusion These findings support previous research indicating that crack use is associated with unprotected sex and multiple sexual partners, as men and women who ceased crack use were less likely to engage in these risky sexual behaviors. Findings demonstrate that treatment for crack use could have a meaningful effect on risky sexual behaviors and HIV/STI prevention.^

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School principals' leadership is key to successful school reform, as is increased student achievement. This nonexperimental ex post facto study tested relationships among secondary school principals' leadership behaviors, school climate, and student achievement. Of 165 secondary school principals from the three largest school districts in South Florida, 58 completed three online survey instruments: the Leadership Practices Inventory, School Climate Inventory-Revised, and researcher-designed Demographic Questionnaire. Student achievement was measured by students' scores on the reading and mathematics Florida Comprehensive Assessment Tests. Three null hypotheses tested relationships among (a) five principals' leadership behaviors and seven domains of school climate; (b) principals' leadership behaviors and student achievement; and (c) principals' leadership behaviors, school climate, and student achievement. Multiple linear regressions were used to determine the degree to which the independent variables predicted the dependent variables for the first two hypotheses. ANOVAs tested possible group differences between the demographic and research variables as controls for the third hypothesis. Partial correlational analyses tested the strength and direction of relationships among leadership behaviors, climate, and achievement. Results revealed partial support of the hypotheses. None of the leadership variables significantly predicted school climate. No significant relationships were found among the five leadership behaviors and student achievement. Demographic group differences in school climate and student achievement were marginally significant. The leadership behaviors of Inspiring a Shared Vision and Enabling Others to Act were positively linked to reading achievement. Partial correlations were found (r .27 to −.35) among school climate variables of Order, Involvement, and Expectation and achievement variables. The Modeling the Way leadership variable was negatively associated with reading achievement. After controlling for gender, years at current school, and years in the district, partial positive correlations were found among leadership, school climate, and student achievement. Inspiring a Shared Vision, Enabling Others to Act, Encouraging the Heart, and Challenging the Process leadership variables were partially correlated to Order, Leadership (Instructional), and Expectation climate variables. Study results should provide policymakers and educators with a leadership profile for school leaders challenging the status quo who can create schools for enhanced student learning and relevance to the needs of students, families, and society.

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ADHD, which refers to one of the most common behavioral problems among children, is subject to controversial arguments surrounding its nature and its primary treatment with psychiatric medications. At the heart of the problem are parents, whose responsibility includes providing pivotal information to clinicians for the diagnosis and deciding whether their children will receive medications. This study investigates the relationship between working parents' willingness to medicate ADHD-like behaviors and the time they are able to spend with their children during a regular workday. The importance of time spent with children derives from the observation that it is likely to influence not only parents' judgments of their children's behaviors but the behaviors themselves. The relationship was investigated using a subsample of 551 working parents (452 parents reporting no child with problems and 99 parents reporting child with problems) drawn from a population-based telephone survey of parents in the Miami-Dade and Broward counties of Florida. A series of path analyses, controlling for selected socio-demographic and family variables, showed that spending more time with their children during a regular workday was significantly related to being less willing to medicate ADHD-like behaviors. The association was stronger for parents reporting having a child with emotional and behavioral problems (β = −.20) and faint for other parents (β = −.06). The interpretation of the study findings emphasizes the vagueness surrounding the nature of ADHD and the events and procedures leading to the diagnosing of a child, as well as the delicate situations in which parents find themselves.

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This study examines the influence of acculturative stress on substance use and HIV risk behaviors among recent Latino immigrants. The central hypothesis of the study is that specific religious coping mechanisms influence the relationship that acculturative stress has on the substance use and HIV-risk behaviors of recent Latino immigrants. Within the Latino culture religiosity is a pervasive force, guiding attitudes, behaviors, and even social interactions. When controlling for education and socioeconomic status, Latinos have been found to use religious coping mechanisms more frequently than their Non-Latino White counterparts. In addition, less acculturated Latinos use religious coping strategies more frequently than those with higher levels of acculturation. Given its prominent role in Latino culture, it appears probable that this mechanism may prove to be influential during difficult life transitions, such as those experienced during the immigration process. This study examines the moderating influence of specific religious coping mechanisms on the relationship between acculturative stress and substance use/HIV risk behaviors of recent Latino immigrants. Analyses for the present study were conducted with wave 2 data from an ongoing longitudinal study investigating associations between pre-immigration factors and health behavior trajectories of recent Latino immigrants. Structural equation and zero-inflated Poisson modeling were implemented to test the specified models and examine the nature of the relationship among the variables. Moderating effects were found for negative religious coping. Higher levels of negative religious coping strengthened an inverse relationship between acculturative stress and substance use. Results also indicated direct relationships between religious coping mechanisms and substance use. External and positive religious coping were inversely related to substance use. Negative religious coping was positively related to substance use. This study aims to contribute knowledge of how religious coping influence's the adaptation process of recent Latino immigrants. Expanding scientific understanding as to the function and effect of these coping mechanisms could lead to enhanced culturally relevant approaches in service delivery among Latino populations. Furthermore this knowledge could inform research about specific cognitions and behaviors that need to be targeted in prevention and treatment programs with this population.

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Perceived discrimination is associated with increased engagement in unhealthy behaviors. We propose an identity-based pathway to explain this link. Drawing on an identity-based motivation model of health behaviors (Oyserman, Fryberg, & Yoder, 2007), we propose that erceptions of discrimination lead individuals to engage in ingroup-prototypical behaviors in the service of validating their identity and creating a sense of ingroup belonging. To the extent that people perceive unhealthy behaviors as ingroup-prototypical, perceived discrimination may thus increase motivation to engage in unhealthy behaviors. We describe our theoretical model and two studies that demonstrate initial support for some paths in this model. In Study 1, African American participants who reflected on racial discrimination were more likely to endorse unhealthy ingroup-prototypical behavior as self-characteristic than those who reflected on a neutral event. In Study 2, among African American participants who perceived unhealthy behaviors to be ingroup-prototypical, discrimination predicted greater endorsement of unhealthy behaviors as self-characteristic as compared to a control condition. These effects held both with and without controlling for body mass index (BMI) and income. Broader implications of this model for how discrimination adversely affects health-related decisions are discussed.