Transformational teaching and adolescent physical activity: multilevel and mediational effects.

BACKGROUND: Regular physical activity is associated with a range of physical and psychological health benefits. In North America the majority of adolescents are insufficiently active. PURPOSE: The purpose of this study was to examine the prospective relationship between adolescents' perceptions of transformational leadership displayed by their school physical education teachers and their own physical activity behaviors, both with respect to within-class physical activity (WCPA) and also leisure time physical activity (LTPA). METHOD: The study used a prospective observational design. Using multilevel structural equation modeling (MSEM), we examined the extent to which adolescents' affective attitudes mediated the effects of teachers' behaviors on adolescents' physical activity responses. Two thousand nine hundred and forty-eight adolescents (M age = 14.33, SD = 1.00, N female = 1,641, 55.7 %) from 133 Grade 8-10 classes in British Columbia (Canada) provided ratings of their physical education teachers' behaviors midway through the school year. Two months later, students completed measures of affective attitudes, WCPA, and LTPA. RESULTS: The results indicated that adolescents' perceptions of transformational teaching explained significant variance in both WCPA and LTPA, and these effects were fully mediated by adolescents' affective attitudes (total indirect effect: b = 0.581, p < 0.001). CONCLUSION: The findings suggest that transformational leadership behaviors displayed by physical education teachers may be an important source of adolescent enjoyment of physical education as well as health-enhancing physical activity involvement within school and outside of school.

Effect of preparation convergence on retention and seating discrepancy of complete veneer crowns.

The purpose of this study was to evaluate the retention and marginal seating discrepancy of complete veneer crown cemented with zinc phosphate cement using various preparation convergence designs. The method employed was that of cementing cast metal crowns onto 46 metal dies fabricated as complete veneer crown preparations with various convergence angles ranging from 0 degrees to 70 degrees and a shoulder finish line. The marginal discrepancy was calculated by measuring the change in crown height before and after cementation using an optical measuring microscope. The force required to remove the crowns from the dies in a vertical direction was determined using an Instron universal testing machine and recorded as retention. The increase in preparation convergence exhibited a wide variation of seating discrepancy between specimens, ranging from 4.58 +/- 1.13 to 73.13 +/- 78.32 microm. Significant tilting of crown was observed as the convergence angle of preparation increased. The retention values ranged from 4.03 +/- 0.61 to 12.12 +/- 0.33 MPa. The Pearson analysis revealed statistically significant correlations between preparation convergence and marginal discrepancy (r = +0.62), and retention (r = -0.91). Crown retention and marginal discrepancy were influenced by the preparation convergence design.

Effect of preparation convergence on retention and seating discrepancy of complete veneer crowns.

The purpose of this study was to evaluate the retention and marginal seating discrepancy of complete veneer crown cemented with zinc phosphate using various preparation convergence designs. The method employed was that of cementing cast metal crowns onto 46 metal dies fabricated as complete veneer crown preparations with various convergence angles ranging from 0 degrees to 70 degrees and a shoulder finish line. The marginal discrepancy was calculated by measuring the change in crown height before and after cementation using an optical measuring microscope. The force required to remove the crowns from the dies in a vertical direction was determined using an Instron universal testing machine and recorded as retention. The increase in preparation convergence exhibited a wide variation of seating discrepancy between specimens, ranging from 4.58 +/- 1.13 to 73.13 +/- 78.32 microm. Significant tilting of crown was observed as the convergence angle of preparation increased. The retention values ranged from 4.03 +/- 0.61 to 12.12 +/- 0.33 MPa. The Pearson analysis revealed statistically significant correlations between preparation convergence and marginal discrepancy (r = +0.62), and retention (r = -0.91). Complete veneer crown retention and marginal discrepancy were influenced by the preparation convergence design.

Archaean ultra-depleted komatiites formed by hydrous melting of cratonic mantle.

Komatiites are ultramafic volcanic rocks containing more than 18 per cent MgO (ref. 1) that erupted mainly in the Archaean era (more than 2.5 gigayears ago). Although such compositions occur in later periods of Earth history (for example, the Cretaceous komatiites of Gorgona Island), the more recent examples tend to have lower MgO content than their Archaean equivalents. Komatiites are also characterized by their low incompatible-element content, which is most consistent with their generation by high degrees of partial melting (30-50 per cent). Current models for komatiite genesis include the melting of rock at great depth in plumes of hot, diapirically rising mantle or the melting of relatively shallow mantle rocks at less extreme, but still high, temperatures caused by fluxing with water. Here we report a suite of ultramafic lava flows from the Commondale greenstone belt, in the southern part of the Kaapvaal Craton, which represents a previously unrecognized type of komatiite with exceptionally high forsterite content of its igneous olivines, low TiO(2)/Al(2)O(3) ratio, high silica content, extreme depletion in rare-earth elements and low Re/Os ratio. We suggest a model for their formation in which a garnet-enriched residue left by earlier cratonic volcanism was melted by hydration from a subducting slab.

Mutations in wheat showing altered field resistance to yellow and brown rust.

Intensive screening of a small population of mutagenised wheat lines revealed a large number of lines with altered resistance to both yellow and brown rust. The parental cultivar Guardian has an intermediate level of adult plant resistance to this disease; mutants were therefore isolated that showed either enhanced resistance or enhanced susceptibility to yellow rust. Seven lines were identified that gave an altered yellow rust disease phenotype as adult plants under both field and greenhouse conditions. Simultaneous field testing for brown rust infection identified two of these lines as having increased resistance to brown rust.

Primary health care for Hispanic children of migrant farm workers.

Providing primary care to children of culturally diverse populations is a challenge for pediatric nurse practitioners and educators. The challenge is intensified when providing care to Hispanic children who are uprooted because their parent(s) are migrant farm workers. The creation of health-focused academic community partnerships is one unique strategy to improve primary care to these children. One such partnership is the ongoing Migrant Family Health Program in which practitioner nursing students and their faculty members provide primary health care to children who are enrolled in a summer education program for migrant children.

Listening to the quiet voices of Hispanic migrant children about health.

There is a paucity of literature related to school-aged migrant children's perceptions of their own health. To best provide culturally competent care, more information is needed about migrant children's experiences. Focus-group methodology allowed the voices of migrant children to be heard by primary health care providers at a summer school program for children of migrant farm workers in south Georgia. Seventy-three children participated in 14 focus-group sessions. Six themes emerged from the data that were analyzed by using a qualitative software system. They are healthy behaviors, acculturation issues, environmental influences, health care actions, health behavior outcomes, and learning needs. Emerging patterns within each theme render insight about these migrant children. The findings suggest implications for pediatric nurses related to culturally competent care.

Hispanic mothers' knowledge and care of their children with respiratory illnesses: a pilot study.

This pilot study was designed to identify Hispanic mothers' knowledge and health practices regarding caring for their children with respiratory illnesses. Using an interview guide, the researchers identified the mothers' perceptions of their children's health, the etiology and symptoms of asthma and other respiratory illnesses, health practices, folk illnesses, services sought and language barriers when using health services. The findings suggest that Hispanic mothers have limited knowledge of respiratory illnesses and use culturally related practices when caring for their sick children. Implications for pediatric nursing practice are discussed, and strategies to improve care for Hispanic families are presented.

Listening to Hispanic mothers: guidelines for teaching.

Teaching Hispanic mothers in a culturally sensitive way to care for their children is a challenge to pediatric nurses. Pediatric nurses must be familiar with customs and the folk medicine practiced by Hispanic mothers. It is very important that the pediatric nurse listens to the voices of Hispanic mothers to determine their health practices, and those that may have been used in their children. Familiarity with folk medicine and health practices will facilitate an appropriate treatment plan and will help to determine whether the mothers' practices are dangerous or beneficial for the child. Pediatric nurses should assess for concurrent use of home remedies and conventional medications to determine if there are any known interactive effects. Finally, increasing the number of pediatric nurses who are fluent in Spanish will enable the voices of Hispanic mothers to be better heard, which in turn, will improve the health status of Hispanic children.

Listening to migrant voices: focus groups on health issues in south Georgia.

This qualitative study utilized focus groups to invite Latino migrant farm workers to express ideas about their health and service needs. Four focus groups composed of Latino men and women were conducted on four different evenings in the same county. Three themes emerged: health care issues, living and working conditions, and social and community issues. Specific needs of the community were also identified by the participants. For the first time, migrant farm workers in Georgia had the opportunity to lend their own voice regarding their concerns and ideas about health and social conditions. The findings from this study are congruent with other studies and provide the basis for developing interventions to enhance the health of migrant farm workers. In addition, the findings have implications for community health nursing and the proposed Vision of 2010: Healthy People in Healthy Communities, whose goals include increased years of healthy life and the elimination of health disparities.

Fears of medical events among school-age children with emotional disorders, parents, and health care providers.

The purpose of this comparative study was to describe the reports of fears of medical events among school-age children with emotional disorders and compare their reports with those of parents and health care providers. A secondary purpose was to determine the reliability of the Child Medical Fear Scale (CMFS) with this population. Thirty children, parents, and health care providers (N = 90) completed the CMFS; the parents and health care providers also completed demographic instruments. The internal consistency reliability was acceptable (alpha = .75) for the CMFS with this population. Overall, the children reported lower fear scores of medical events than in previous research studies. Boys reported lower fear scores (p = .03) than girls. There was a statistical difference (p = .006) between the mean scores of the children and those of the parents and health care providers, with the children reporting less fear. The CMFS is useful among children with emotional disorders both in the clinical setting and in research.

The relationship between preparation convergence and retention of extracoronal retainers.

PURPOSE: Although traditional ideal convergence (the sum of taper of the opposite sides) for crown preparation has been arbitrarily set at 4 degrees to 10 degrees, some believe absolute parallelism yields the highest retention. This study examined the relationship between the degree of convergence of a machined metal die and the retention of its casting. MATERIALS AND METHODS: The method used was that of cementing cast metal crowns onto full crown preparations on brass dies with varying convergence angles, and then recording the force required to remove the crowns from the dies in a vertical direction using a Tate-Emery Testing Machine and Load Indicator. RESULTS: It was found that retention (i.e., the force needed to remove the cemented castings from the die in their common long axis) increases from 0 degree convergence to peak between 6 degrees to 12 degrees convergence. It also seems that a critical film thickness does exist for optimum retention, and that film thicknesses smaller than the critical thickness may be responsible for the phenomenon that we have observed and directly related to the convergence angle itself. CONCLUSIONS: There seems to be experimental data supporting the use of traditionally taught convergence. Our study found that convergence angles between 6 degrees and 12 degrees seem to be optimum for tooth crown preparation when one plans to use zinc phosphate cement. Convergence angles of less than 6 degrees may not be desirable even if they can be clinically achieved. The results of our study indicate that a relationship exists between the convergence angle and the critical cement thickness that is necessary to realize the maximum strength properties of zinc phosphate cement.

Implications of metronidazole pharmacodynamics for therapy of trichomoniasis.

A liquid chromatographic technique for the detection of metronidazole (MDZ) and its major metabolites, combined with a vaginal sampling technique employing extraction of drug from vaginal swabs, was used to evaluate the concentration of MDZ in the vaginal fluid during therapy. Wide variation in the absolute concentration of unchanged drug was noted, although the average vaginal levels were about half the serum concentration 2 h after treatment had been initiated and comparable to the serum levels 6 and 24 h after treatment. Oral administration of MDZ invariably resulted in the presence of the drug in the serum and urine but the drug was not always detected in the vaginal secretions. The presence of the relatively inactive acetyl metabolite in the vaginal fluid of patients who failed to respond to therapy for trichomoniasis suggested the possible role of drug modification as a contributing factor in the lack of therapeutic success. The presence of MDZ in women in whom the cervix had previously been surgically removed attests to the transport or transudation of the drug across the vaginal epithelium without involvement of the secretory activity of the cervix.

Role of proprioceptive reflexes in control of feeding muscles of Aplysia.

Stretching the muscles of the buccal mass of Aplysia evoked proprioceptive reflexes. These consisted of a direct reflex in which the stretched muscle contracted and a crossed reflex in which the contralateral homolog of the stretched muscle contracted as well. Both reflexes were accompanied by corresponding changes in neural activity in the buccal nerves. The muscle contraction and efferent neural activity were abolished by blocking synaptic transmission in the buccal ganglia. Blocking neuromuscular transmission blocked the contractions but not the stretch-induced afferent neural activity. Proprioceptive responses were obtained from isolated buccal nerve-muscle preparations. Both tonic on- and on-off responses were observed. These responses persisted after blocking synaptic transmission at the muscle, indicating that they were due to afferent fibers rather than peripheral interneurons. Proprioceptive neurons with centrally located cell bodies were found. These included previously identified neurons B4 and B5 as well as small cells. Proprioceptive neurons responded to muscle stretch with peripherally initiated axonal spikes that conducted into the central nervous system (CNS) and preceded their somatic spikes. These responses persisted after blocking synaptic transmission in the CNS. Several motor neurons were found. When intracellularly stimulated, these evoked contractions of their target muscle even after blocking synaptic transmission in the CNS. The motor neurons responded synaptically to stretching the ipsilateral muscle. Some responded to stretching of the contralateral homologous muscle as well. The motor neurons differed in their axonal projections, with some projecting only ipsilaterally, others bilaterally. The majority of motor neurons were inhibited by muscle stretch due to inhibitory monosynaptic input from the proprioceptive cells B4 and B5. The stretch reflex occurred when the motor neurons fired due to postinhibitory rebound. The synaptic organization of the reflex was considered.