611 research outputs found
More Exercise for Seniors: : Opportunities and Challenges
No full textMechelen, W. van [Promotor]Greef, M.H.G. de [Copromotor]Hopman-Rock, M. [Copromotor
HopmanOpenPracticesDisclosure – Supplemental material for Production Practice During Language Learning Improves Comprehension
No full textSupplemental material, HopmanOpenPracticesDisclosure for Production Practice During Language Learning Improves Comprehension by Elise W. M. Hopman and Maryellen C. MacDonald in Psychological Science</p
Prevention of cognitive decline : Effectiveness of physical exercise and vitamin B supplementation
No full textMechelen, W. van [Promotor]Chin A Paw, J.M.M. [Copromotor]Hopman-Rock, M. [Copromotor
HopmanSupplementalMaterial – Supplemental material for Production Practice During Language Learning Improves Comprehension
No full textSupplemental material, HopmanSupplementalMaterial for Production Practice During Language Learning Improves Comprehension by Elise W. M. Hopman and Maryellen C. MacDonald in Psychological Science</p
Closure of the stop-band in photonic wire Bragg gratings
No full textPhotonic Wire Bragg Gratings, made by periodic insertion of lateral rectangular recesses into photonic wires in silicon-on-insulator, can provide large reflectivity with short device lengths because of their large index contrast. This type of design shows a counter-intuitive behaviour, as we demonstrate - using experimental and numerical data - that it can have low or null reflectance, even for large indentation values. We provide physical insight into this phenomenon by developing a model based on Bloch mode theory, and are able to find an analytical expression for the frequency at which the grating does not sustain the stop-band. Finally we demonstrate that the stop-band closing effect is a general phenomenon that may occur in various types of periodic device that can be modeled as transmission line structures
Influence of iron status and iron supplements on natural killer cell activity in trained women runners
No full textTwenty-two trained women runners (V̇Opeak 48.1 + 1.2 ml × kg × min) were divided into an iron supplement (n = 13) or placebo group (n = 9) based on initial serum ferritin concentration (24.2 ± 2.9 and 58.5 ± 4.0 μg × l, respectively). Exercise consisted of a 35-min run (80% V̇Opeak) and was performed at week 0 (WK0), after two weeks of intensified training (WK2) and after eight weeks recovery training (WK10). The eight weeks recovery training were concomitant with subjects taking iron supplements or placebo in a double blind fashion. Concentrations of serum ferritin, serum iron and total iron binding capacity were assessed pre-exercise and complete blood count, natural killer cell activity (NKACT), and cell surface markers for CD3+, CD4+, CD3+,CD8+, CD3-, CD16+, CD56+ cells were determined both pre- and post-exercise. Serum ferritin concentrations were significantly (p < 0.05) increased on WK10 compared to WK2 (time effect). NKACT (%Iysis) and NK cell number was lower (p < 0.05) at WK0 for supplement (42.9 ± 1.9% and 305.5 ± 15.0 × 10 × l, respectively) compared to placebo groups (50.9 ± 2.0 and 406.1 ± 25.6, respectively). Two weeks of intensified training did not alter indices of host defense. In conclusion, NKACT and NK cell numbers were lower in subjects with greater body mass and lower iron stores (p < 0.05), but were not significantly altered after two weeks of intensified training or when serum ferritin levels increased
The effect of moderate aerobic exercise and relaxation on secretory immunoglobulin A
No full textA deficiency in secretory immunoglobulin A (sIgA) is associated with recurrent upper respiratory tract infections both in the general community and in elite athletes. The aim of this paper was to investigate the effect of aerobic exercise and relaxation on various indices of sIgA in 12 male and 8 female adults who varied in levels of recreational activity. Salivary samples were obtained before, immediately after and 30 minutes after an incremental cycle ergometer test to fatigue, after 30 minutes of cycling at 30 % or 60 % of maximum heart rate, and after 30 minutes of relaxation with guided imagery. Each session was run on a separate day. When expressed in relation to changes in salivary flow rate, sIgA did not change after exercise. However, both the absolute concentration and secretion rate of sIgA increased during relaxation (167 ± 179 μg · ml-1, p < 0.001; and 37 ± 71 μg · min-1, p < 0.05 respectively). Nonspecific protein increased more than sIgA during incremental exercise to fatigue (decrease in the sIgA/protein ratio 92 ± 181 μg · mg protein-1, p < 0.05), but sIgA relative to protein did not change during relaxation. Our findings suggest that sIgA secretion rate is a more appropriate measure of sIgA than sIgA relative to protein, both for exercise and relaxation. These data suggest the possibility of using relaxation to counteract the negative effects of intense exercise on sIgA levels
Tennis, incidence of URTI and salivary IgA
No full textTennis played at an elite level requires intensive training characterized by repeated bouts of brief intermittent high intensity exercise over relatively long periods of time (1 - 3 h or more). Competition can place additional stress on players. The purpose of this study was to investigate the temporal association between specific components of tennis training and competition, the incidence of upper respiratory tract infections (URT1), and salivary IgA, in a cohort of seventeen elite female tennis players. Timed, whole unstimulated saliva samples were collected before and after selected 1-h training sessions at 2 weekly intervals, over 12 weeks. Salivary IgA concentration was measured by ELISA and IgA secretion rate calculated (mug IgA x ml(-1) x ml saliva x min(-1)). Players reported URTI symptoms and recorded training and competition in daily logs. Data analysis showed that higher incidence of URTI was significantly associated with increased training duration and load, and competition level, on a weekly basis. Salivary IgA secretion rate (S-IgA) dropped significantly after 1 hour of tennis play. Over the 12-week period, pre-exercise salivary IgA concentration and secretion rate were directly associated with the amount of training undertaken during the previous day and week (p < 0.05). However, the decline in S-IgA after 1 h of intense tennis play was also positively related to the duration and load of training undertaken during the previous day and week (p < 0.05). Although exercise-induced suppression of salivary IgA may be a risk factor, it could not accurately predict the occurrence of URTI in this cohort of athletes
Cortisol, DHEA, performance and training in elite swimmers
No full textSalivary cortisol (C) and DHEA concentrations were measured in 9 elite swimmers (4 female and 5 male) over a 37-week period, 5 to 12 times per swimmer, before 68 competitions. For female and male swimmers, no significant relationship was found between C, DHEA and performance. For the whole group, C was negatively correlated with week number of training (r = -0.31, p < 0.01). The incorporation of the cumulated distance swum as a second variable in the regression increased r to 0.56 (p < 0.01). The higher the cumulated distance swum, the higher C. No significant relationship was found between DHEA and distance swum. For individual swimmers, 3 of 4 females showed a significant negative relationship between C and cumulated dry-land training. No equivalent relationship was found for DHEA. The 2 males practicing dry-land training showed a significant and negative relationship between DHEA and cumulated dry-land training. No equivalent relationship was found for C. Thus, C and DHEA were not good predictors of swimming performance. C for individual females, and DHEA for individual males were considered useful markers for dry-land training stress
Unraveling the Hidden Curriculum. Values in Youth Care Interventions and Youth Policy
No full textThemes such as “effectiveness” and “evidence-based practice” dominate current debates about and within the professional field of youth care. The field seems to focus almost solely on the effectiveness of interventions and policy measures and there appears to be a general consensus on the objectivity and neutrality of interventions, policy measures and of the effectiveness research that follows from it. However, child rearing—including the professional re-education of children— entails more than encouraging desired behavior and correcting inappropriate behavior. It also includes normative ideas about this desired behavior and about issues like “good parenting” and “healthy development”. Although no one would argue that effectiveness issues are a mere detail, the assessment and evaluation of interventions and policy measures on effectiveness only, leaves these normative matters undiscussed.
The research presented in this dissertation aims at unraveling this “hidden curriculum” of both youth care interventions and youth policy measures, by analyzing and clarifying the role values may play in this specific professional field. Five case studies have been conducted, each consisting of content analysis of relevant documents (i.e. articles about an intervention, policy reports), and of interviews and observations. The results of these case studies show that values are indeed expressed in youth care interventions and in youth policy measures. In contrast to the claims of objectivity and neutrality, interventions and policy measures convey specific value perspectives.
In general protective values, such as security or achievement, are expressed in all of the five case studies. Some interventions combine these protective values with growth-oriented values, for instance self-direction or hedonistic values. Others combine them with values such as conformity, indicating a conservative value perspective. Differences were found between the values expressed in the theory of an intervention and the values expressed in the actual practice of an intervention. This may indicate that personal, professional or institutional values may play a role in executing an intervention. The results also seem to imply that cultural values may have some influence on the execution of an intervention. For youth policy, differences in values are mainly found between the social groups the policy measures intent to target. Overall, the results are indicative of values aimed at socialization and integration of children and families in existing social structures and norms.
The results have important implications for the professional field of youth care and the research conducted in it. Differences between values in the theory and in the practice of an intervention imply that it may serve effectiveness research to pay attention to the subject of values: Professionals may struggle with the implicit values of an intervention and may adapt the intervention to better suit the values they believe are important. Likewise, fall out of clients during treatment may be explained by a discrepancy between the implicit values of an intervention and the personal values of parents and children. Moreover, the results of this research may foster a debate about the position of the professional field of youth care and the role they foresee for themselves within society
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