Identification of biological and environmental risk factors for language delay: The Let's Talk STEPS study

The aim of this population-based study was to identify demographic factors for language delays at an early age. The risk analysis covered 11 biological and 8 environmental factors. The mothers’ concerns regarding language development were also examined. A total of 226 children from a Finnish cohort study were invited to participate in language assessments at 36 months. The test results for word finding and language comprehension were compared with parental questionnaires about children's vocabulary at 13 and 24 months.Regression analysis revealed that the father's social class (t = −2.79, p = 0.006) and working full time (t = −2.86, p = 0.005) significantly predicted children's language delay. In addition, language comprehension was significantly predicted by the mother's social class (t = −2.06, p = 0.041) and by gender, with an advantage to girls (t = −2.71, p = 0.008). Vocabulary at 24 months was a powerful predictor for lexical development (t = 4.58, p < 0.0001) and language comprehension (t = 4.85, p < 0.0001) at 36 months. Mothers’ concerns were correlated with children's limited lexicons as early as 24 months (r = 0.31, p < 0.0001) and poor language comprehension (r = −0.35, p < 0.0001) at 36 months. Mothers were especially concerned if the parents needed special education during school years.At the population-level, gender was the most powerful biological factor in predicting language delays. Similarly, both parents’ social status had predictive value for the child's language development. In addition, it was found that the mother's concern about her child's slow language acquisition should be taken into account when making decisions regarding special support.     

Treadmill based reference running data for healthy subjects is dependent on speed and morphological parameters

ObjectiveTo obtain spatiotemporal and dynamic running parameters of healthy participants and to identify relationships between running parameters, speed, and physical characteristics.MethodA dynamometric treadmill was used to collect running data among 417 asymptomatic subjects during speeds ranging from 10 to 24 km/h. Spatiotemporal and dynamic running parameters were calculated and measured.ResultsResults of the analyses showed that assessing running parameters is dependent on running speed. Body height correlated with stride length (r = 0.5), cadence (r = −0.5) and plantar forefoot force (r = 0.6). Body mass also had a strong relationship to plantar forefoot forces at 14 and 24 km/h and plantar midfoot forces at 14 and 24 km/h.ConclusionThis reference data base can be used in the kinematic and kinetic evaluation of running under a wide range of speeds.     

The influence of the number of toys in the environment on toddlers’ play

We tested the hypothesis that an environment with fewer toys will lead to higher quality of play for toddlers. Each participant (n = 36) engaged in supervised, individual free play sessions under two conditions: Four Toy and Sixteen Toy. With fewer toys, participants had fewer incidences of toy play, longer durations of toy play, and played with toys in a greater variety of ways (Z = −4.448, p < 0.001, r = −0.524; Z = 2.828, p = 0.005, r = 0.333; and Z = 4.676, p < 0.001, r = 0.55, respectively). This suggests that when provided with fewer toys in the environment, toddlers engage in longer periods of play with a single toy, allowing better focus to explore and play more creatively. This can be offered as a recommendation in many natural environments to support children’s development and promote healthy play.     

Sense of body ownership in patients affected by functional motor symptoms (conversion disorder)

Background and aimPatients with functional neurological symptoms are commonly seen in neurological practice. Nevertheless their aetiopathology remains unclear. We have recently shown that patients affected by functional motor symptoms (FMS) present lower interoceptive awareness and higher alexithymia levels than healthy controls. Nevertheless sense of body ownership has never been studied in FMS patients.The aim of the present study was to systematically investigate the sense of body ownership, with the rubber hand illusion (RHI) paradigm, in patients with FMS and healthy controls.Materials and methodsWe included in the study 16 patients with FMS and 18 healthy controls (HC). Patients and HC were asked to complete the Toronto Alexithymia Scale (TAS-20) and the self-consciousness scale (self-objectification questionnaire). All participants underwent the RHI paradigm: illusionary experience was measured by self-report and by proprioceptive alteration.ResultsA Mann–Whitney U test performed revealed that FMS (median = 2.11) participants embodied the rubber hand to the same extent than HC participants (median = 2.0, Z = −0.86, p > 0.05, r = −0.15). The same test revealed no significant difference in the Proprioceptive Drift experience between FMS (median = 0.0) and HC participants (median = −0.5, Z = −0.96, p > 0.05, r = −0.16).ConclusionsOur study revealed that sense of body ownership is not impaired in patients affected by FMS. This, together with the results from our previous experiment (studying the interoceptive awareness), supports the hypothesis that interoceptive awareness and sense of body ownership may be dissociated in patients with FMS.     

Match performance and physical capacity of players in the top three competitive standards of English professional soccer

The aim of this study was to compare the match performance and physical capacity of players in the top three competitive standards of English soccer. Match performance data were collected from players in the FA Premier League (n = 190), Championship (n = 155) and League 1 (n = 366) using a multiple-camera system. In addition, a selection of players from the Premier League (n = 56), Championship (n = 61) and League 1 (n = 32) performed the Yo-Yo intermittent endurance test level 2 (Yo-Yo IE2) to determine physical capacity. Players in League 1 and the Championship performed more (p < .01) high-intensity running than those in the Premier League (Effect Size [ES]: 0.4–1.0). Technical indicators such as pass completion, frequency of forward and total passes, balls received and average touches per possession were 4–39% higher (p < .01) in the Premier League compared to lower standards (ES: 0.3–0.6). Players also covered more (p < .05) high-intensity running when moving down (n = 20) from the Premier League to the Championship (ES: 0.4) but not when players moved up (n = 18) standards (ES: 0.2). Similar Yo-Yo IE2 test performances were observed in Premier League, Championship and League 1 players (ES: 0.2–0.3). Large magnitude relationships (p < .05) were observed between Yo-Yo IE2 test performances and the total and high-intensity running distance covered in both Championship (r = .56 and .64) and Premier League matches (r = .61 and .54). The data demonstrate that high-intensity running distance was greater in players at lower compared to higher competitive standards despite a similar physical capacity in a subsample of players in each standard. These findings could be associated with technical characteristics inherent to lower standards that require players to tax their physical capacity to a greater extent but additional research is still required to confirm these findings.     

Assessing Decentering: Validation,Psychometric Properties,and Clinical Usefulness of the Experiences Questionnaire in a Spanish Sample

Decentering is defined as the ability to observe one’s thoughts and feelings in a detached manner. The Experiences Questionnaire (EQ) is a self-report instrument that originally assessed decentering and rumination. The purpose of this study was to evaluate the psychometric properties of the Spanish version of EQ-Decentering and to explore its clinical usefulness. The 11-item EQ-Decentering subscale was translated into Spanish and psychometric properties were examined in a sample of 921 adult individuals, 231 with psychiatric disorders and 690 without. The subsample of nonpsychiatric participants was also split according to their previous meditative experience (meditative participants, n = 341; and nonmeditative participants, n = 349). Additionally, differences among these three subgroups were explored to determine clinical validity of the scale. Finally, EQ-Decentering was administered twice in a group of borderline personality disorder, before and after a 10-week mindfulness intervention. Confirmatory factor analysis indicated acceptable model fit, _sbχ² = 243.8836 (p < .001), CFI = .939, GFI = .936, SRMR = .040, and RMSEA = .06 (.060–.077), and psychometric properties were found to be satisfactory (reliability: Cronbach’s α = .893; convergent validity: r > .46; and divergent validity: r < − .35). The scale detected changes in decentering after a 10-session intervention in mindfulness (t = − 4.692, p < .00001). Differences among groups were significant (F = 134.8, p < .000001), where psychiatric participants showed the lowest scores compared to nonpsychiatric meditative and nonmeditative participants. The Spanish version of the EQ-Decentering is a valid and reliable instrument to assess decentering either in clinical and nonclinical samples. In addition, the findings show that EQ-Decentering seems an adequate outcome instrument to detect changes after mindfulness-based interventions.     

Promoting an equitable and supportive school climate in high schools: The role of school organizational health and staff burnout

In response to persistent racial disparities in academic and behavioral outcomes between Black and White students, equitable school climate has drawn attention as a potential target for school reform. This study examined differences in Black and White students' experiences of school climate and explored whether indicators of school organizational health and staff burnout moderated differences in students' school experiences by race. Utilizing hierarchical linear modeling with a sample of 18,397 Black students (n = 6228) and White students (n = 12,169) and 2391 school staff in 53 schools, we found a consistent pattern of racial inequalities, such that Black students reported less positive experiences than White students across three indicators of school climate (caring γ = − 0.08, p < .001; equity γ = − 0.05, p = .007; and engagement γ = − 0.05, p < .001). In addition, we found significant, positive associations between aggregated staff-report of school organizational health and student-reported school climate (e.g., staff affiliation and student-perceived equity, γ = 0.07, p < .001). Surprisingly, a number of school organizational health indicators were more strongly associated with positive perceptions of school climate among White students than Black students, translating into greater racial disparities in perceived school climate at schools with greater organizational health (e.g., supportive leadership by race on student-perceived engagement, γ = − 0.03, p = .042). We also found negative associations between staff-reported burnout and students' experience of equity, such that the racial gap was smaller in schools with high ratings of burnout (γ = 0.04, p = .002). These findings have implications for educators and education researchers interested in promoting school social contexts that equitably support student engagement and success.     

Facial width-to-height ratio and celebrity endorsements

This study hypothesized that the facial WHR of celebrity endorsers is associated with their endorsement income. Our sample consisted of the top 100 male and female celebrity endorsers (male = 50 and female = 50) in Seoul. The average annual total endorsement income of celebrity endorsers in 2012 was $1,691,924 for male endorsers and $1,684,474 for female endorsers. A statistical analysis demonstrated a significant negative correlation between celebrity endorsers’ facial WHR and their endorsement income in 2012 among male (r = −.390, p = .007, n = 47) but not among female (r = .166, p = . 248, n = 50) endorsers. Our findings imply that males with narrower faces are more popular among the media as well as among advertisers. Our study is the first to explore the relationship between physical features, such as facial WHR and monetary income in the entertainment industry.     

Variability of a “force signature” during windmill softball pitching and relationship between discrete force variables and pitch velocity

This study assessed reliability of discrete ground reaction force (GRF) variables over multiple pitching trials, investigated the relationships between discrete GRF variables and pitch velocity (PV) and assessed the variability of the “force signature” or continuous force-time curve during the pitching motion of windmill softball pitchers. Intraclass correlation coefficient (ICC) for all discrete variables was high (0.86–0.99) while the coefficient of variance (CV) was low (1.4–5.2%). Two discrete variables were significantly correlated to PV; second vertical peak force (r(5) = 0.81, p = 0.03) and time between peak forces (r(5) = −0.79; p = 0.03). High ICCs and low CVs support the reliability of discrete GRF and PV variables over multiple trials and significant correlations indicate there is a relationship between the ability to produce force and the timing of this force production with PV. The mean of all pitchers’ curve-average standard deviation of their continuous force-time curves demonstrated low variability (CV = 4.4%) indicating a repeatable and identifiable “force signature” pattern during this motion. As such, the continuous force-time curve in addition to discrete GRF variables should be examined in future research as a potential method to monitor or explain changes in pitching performance.     

Maternal postpartum depressive symptoms and infant externalizing and internalizing behaviors

Maternal postpartum depression has been shown to be one of the main predictors of externalizing and internalizing behaviors in toddlers and adolescents. Research suggests that presence of such behaviors can be observed as early as infancy. The current study uses longitudinal data from 247 mothers to examine the relationship between postpartum depressive symptoms at 8 weeks and the infant's externalizing and internalizing behaviors at 12 months. In unadjusted linear regression models, there were associations between postpartum depressive symptoms and infant externalizing behaviors (β = 0.082, SE = 0.032, p = 0.012) and internalizing behaviors (β = 0.111, SE = 0.037, p = 0.003). After controlling for potential confounding factors, including maternal age, race, education, home ownership, smoking status in the postpartum period, marital status, parenting stress, and happiness from becoming a parent, the associations between postpartum depressive symptoms and infant externalizing (β = 0.051, SE = 0.034, p = 0.138) and internalizing behaviors (β = 0.077, SE = 0.040, p = 0.057) were reduced and became non-significant. Furthermore, in these models the total amount of variance explained was 17.2% (p < 0.0001) for externalizing behaviors and 10.5% (p < 0.01) for internalizing behaviors; the only significant predictor of externalizing behaviors was maternal age (β = −0.074, SE = 0.030, p = 0.014), and of internalizing behaviors was white non-Hispanic ethnicity (β = −1.33, SE = 0.378, p = 0.0005). A combined effect of the confounding factors seems to explain the finding of no significant independent association between postpartum depressive symptoms and infant externalizing and internalizing behaviors.     

Increased forefoot loading is associated with an increased plantar flexion moment

The aim of this study was to identify the cascade of effects leading from alterations in force generation around the ankle joint to increased plantar pressures under the forefoot. Gait analysis including plantar pressure measurement was performed at an individually preferred and a standardized, imposed gait velocity in diabetic subjects with polyneuropathy (n = 94), without polyneuropathy (n = 39) and healthy elderly (n = 19). The plantar flexion moment at 40% of the stance phase was negatively correlated with the displacement rate of center of pressure (r = ?.749, p < .001 at the imposed, and r = ?.693, p < .001 at the preferred gait velocity). Displacement rate of center of pressure was strongly correlated with forefoot loading (r = ?.837, p < .001 at the imposed, and r = ?.731, p < .001 at the preferred gait velocity). People with a relatively high plantar flexion moment at 40% of the stance phase, have a faster forward transfer of center of pressure and consequently higher loading of the forefoot. This indicates that interventions aimed at increasing the control of the roll-off of the foot may contribute to a better plantar pressure distribution.     

The relationship between hip,knee and ankle muscle mechanical characteristics and gait transition speed

The purpose of the present study was to explore the relationship between mechanical characteristics of hip, knee and ankle extensor and flexor muscle groups and gait transition speed. The sample included 29 physically active male adults homogenized regarding their anthropometric dimensions. Isokinetic and isometric leg muscle mechanical characteristics were assessed by an isokinetic dynamometer, while individual walk-to-run (WRT) and run-to-walk transition speeds (RWT) were determined using the standard increment protocol. The relationship between transition speeds and mechanical variables scaled to body size was determined using Pearson correlation and stepwise linear regression. The highest correlations were found for isokinetic power of ankle dorsal flexors and WRT (r = .468, p < .01) and the power of hip extensors and RWT (r = .442, p < .05). These variables were also the best predictors of WRT and RWT revealing approximately 20% of explained variance. Under the isometric conditions, the maximal force and rate of force development of hip flexors and ankle plantar flexors were moderately related with WRT and RWT (ranged from r = .340 to .427). The only knee muscle mechanical variable that correlated with WRT was low velocity knee flexor torque (r = .366, p < .05). The results generally suggest that the muscle mechanical properties, such as the power of ankle dorsal flexors and hip extensors, influence values of WRT and RWT.     

The relationship between allometry and preferred transition speed in human locomotion

The purpose of this study was to explore the relationships between preferred transition speed (PTS) and anthropometric characteristics, body composition and different human body proportions in males. In a sample of 59 male students, we collected anthropometric and body composition data and determined individual PTS using increment protocol. The relationships between PTS and other variables were determined using Pearson correlation, stepwise linear and hierarchical regression. Body ratios were formed as quotient of two variables whereby at least one significantly correlated to PTS. Circular and transversal (except bitrochanteric diameter) body dimensions did not correlate with PTS. Moderate correlations were found between longitudinal leg dimensions (foot, leg and thigh length) and PTS, while the highest correlation was found for lower leg length (r = .488, p < .01). Two parameters related to body composition showed weak correlation with PTS: body fat mass (r = −.250, p < .05) and amount of lean leg mass scaled to body weight (r = .309, p < .05). Segmental body proportions correlated more significantly with PTS, where thigh/lower leg length ratio showed the highest correlation (r = .521, p < .01). Prediction model with individual variables (lower leg and foot length) have explained just 31% of PTS variability, while model with body proportions showed almost 20% better prediction (R² = .504). These results suggests that longitudinal leg dimensions have moderate influence on PTS and that segmental body proportions significantly more explain PTS than single anthropometric variables.     

The role of motion platform on postural instability and head vibration exposure at driving simulators

This paper explains the effect of a motion platform for driving simulators on postural instability and head vibration exposure. The sensed head level-vehicle (visual cues) level longitudinal and lateral accelerations (a_x,sensed = a_{x_head} and a_y,sensed = a_{y_head}, a_yv = a_{y_veh} and a_yv = a_{y_veh}) were saved by using a motion tracking sensor and a simulation software respectively. Then, associated vibration dose values (VDVs) were computed at head level during the driving sessions. Furthermore, the postural instabilities of the participants were measured as longitudinal and lateral subject body centre of pressure (X_CP and Y_CP, respectively) displacements just after each driving session via a balance platform. The results revealed that the optic-head inertial level longitudinal accelerations indicated a negative non-significant correlation (r = −.203, p = .154 > .05) for the static case, whereas the optic-head inertial longitudinal accelerations depicted a so small negative non-significant correlation (r = −.066, p = .643 > .05) that can be negligible for the dynamic condition. The X_CP for the dynamic case indicated a significant higher value than the static situation (t(47), p < .0001). The VDV_x for the dynamic case yielded a significant higher value than the static situation (U(47), p < .0001). The optic-head inertial lateral accelerations resulted a negative significant correlation (r = −.376, p = .007 < .05) for the static platform, whereas the optic-head inertial lateral accelerations showed a positive significant correlation (r = .418, p = .002 < .05) at dynamic platform condition. The VDV_y for the static case indicated a significant higher value rather than the dynamic situation (U(47), p < .0001). The Y_CP for the static case yielded significantly higher than the dynamic situation (t(47), p = .001 < 0.05).     

Effect of an intensified training period on well-being indices,recovery and psychological aspects in professional soccer players

IntroductionIntensified training periods (IT) are associated with fatigue increase and psychological variations.ObjectiveThis investigation aimed to examine the perceived well-being, recovery quality and psychological responses during an IT.MethodsFifteen professional soccer players (mean ± SD: age: 24 ± 1 years, body mass: 71.3 ± 15.1 kg, height: 178.0 ± 6.1 cm) completed a 6-week training program consisting of 2 weeks of basic training (BT) and 4 weeks of IT. They were tested before (T1) and after (T2) the IT. Training load (TL) perception, strain and monotony were measured by the session-RPE method. Well-being indices (sleep quality, fatigue level, stress and delayed-onset muscular soreness [DOMS]) and total quality recovery (TQR) were recorded before each training session. The profile of mood states (POMS) and the Ottowa mental skills assessment tool (OMSAT)-3 were conducted before and after IT.ResultsNo significant difference was found after IT in OMSAT-3 scores (p > 0.05). TL, monotony and strain increased during IT (p < 0.001). Moreover, well-being indices (stress, sleep quality, fatigue level and DOMS) increased (p < 0.001) and TQR decreased (p < 0.001) during IT. The IT increased total mood disturbance (TMD, p < 0.001), tension (p < 0.05) and fatigue (p < 0.01) and decreased vigor (p < 0.001). Significant relationships were found between TL and Hooper Index (HI), TQR and TMD (r = 0.58, 0.65, −0.57, respectively; all p < 0.05).ConclusionThe findings of this investigation suggested that mental ability was not sensitive to fatigue caused by training load intensification. However, perceived well-being, recovery state and mood were found to be sensitive measures and may provide coaches with information about wellness and psychological state of soccer players during IT.     

Intelligence and semen quality are positively correlated

Human cognitive abilities inter-correlate to form a positive matrix, from which a large first factor, called ‘Spearman's g’ or general intelligence, can be extracted. General intelligence itself is correlated with many important health outcomes including cardio-vascular function and longevity. However, the important evolutionary question of whether intelligence is a fitness-related trait has not been tested directly, let alone answered. If the correlations among cognitive abilities are part of a larger matrix of positive associations among fitness-related traits, then intelligence ought to correlate with seemingly unrelated traits that affect fitness—such as semen quality. We found significant positive correlations between intelligence and 3 key indices of semen quality: log sperm concentration (r = .15, p = .002), log sperm count (r = .19, p < .001), and sperm motility (r = .14, p = .002) in a large sample of US Army Veterans. None was mediated by age, body mass index, days of sexual abstinence, service in Vietnam, or use of alcohol, tobacco, marijuana, or hard drugs. These results suggest that a phenotype-wide fitness factor may contribute to the association between intelligence and health. Clarifying whether a fitness factor exists is important theoretically for understanding the genomic architecture of fitness-related traits, and practically for understanding patterns of human physical and psychological health.     

Profiling movement quality and gait characteristics according to body-mass index in children (9–11 y)

Obese children move less and with greater difficulty than their normal-weight counterparts. Whilst the effect of high BMI on cardiovascular fitness is well known, the effect on movement quality characteristics during a standardised fitness test has not been investigated. The aims of this study were, to characterise the movement quality of children performing the multi-stage fitness test (MSFT), and, report how movement quality characteristics cluster according to weight status. One hundred and three children (10.3 ± 0.6 y, 1.42 ± 0.08 m, 37.8 ± 9.3 kg, BMI; 18.5 ± 3.3 kg m²) performed the MSFT whilst wearing an ankle mounted accelerometer. BMI groups were used to classify children as underweight (UW), normal weight (NW), overweight (OW) and obese (OB). Characteristics of movement were profiled using a clustering algorithm. Spearman’s rho was used to assess relationship with BMI group, and a Mann-Whitney U test was used to assess differences between BMI groups. Obese children had significantly lower spectral purity than every other group and significantly lower time to exhaustion (TTE) than UW and NW children (P < 0.05). BMI was clustered with stride profile and TTE with spectral purity. Significant negative correlations (P < 0.05) were found between BMI and TTE (r = −0.25), spectral purity (r = −0.24), integrated acceleration (r = −0.22), stride angle (r = −0.23) and stride variability (r = −0.22). This was the first study to report the spectral purity of children’s gait. Further analysis unveiled key performance characteristics that differed between BMI groups. These were (i) representative of children’s performance during the MSFT and, (ii) significantly negatively correlated with BMI.     

L'évaluation du burnout de Pines : adaptation et validation en version française de l'instrument Burnout Measure Short version (BMS-10)

The aim of this research present the psychometrics properties of a global measure of burnout. This study concern a framework of Pines and Aronson (1988). The aim of the study consist in testing the structure validity, a confirmatory factorial structure and a reliability of the BMS (“Burnout Measure Short version”). The results show that a confirmatory factor analysis and the temporal stability led to a BMS in French version (participants: N1 = 111; for reliability: N2 = 32). The unidimensional dimension of BMS was correlated with other measures (positively with “emotional exhaustion” [r = 0.53; p < 00] and negatively with “work satisfaction” [r = –0.19; p<0.02]). Practical implications are discussed.     

Do intermediate- and higher-order principal components contain useful information to detect subtle changes in lower extremity biomechanics during running?

Recently, a principal component analysis (PCA) approach has been used to provide insight into running pathomechanics. However, researchers often account for nearly all of the variance from the original data using only the first few, or lower-order principal components (PCs), which are often associated with the most dominant movement patterns. In contrast, intermediate- and higher-order PCs are generally associated with subtle movement patterns and may contain valuable information about between-group variation and specific test conditions. Few investigations have evaluated the utility of intermediate- and higher-order PCs based on observational cross-sectional analyses of different cohorts, and no prior studies have evaluated longitudinal changes in an intervention study. This study was designed to test the utility of intermediate- and higher-order PCs in identifying differences in running patterns between different groups based on three-dimensional bilateral lower-limb kinematics. The results reveal that differences between sex- and age-groups of 128 runners were observed in the lower- and intermediate-order PCs scores (p < 0.05) while differences between baseline and following a 6-week muscle strengthening program for 24 runners with patellofemoral pain were observed in the higher-order PCs scores (p < 0.05), which exhibited a moderate correlation with self-reported pain scores (r = −0.43; p < 0.05).     

Impact of the telephone motivational interviewing on the colorectal cancer screening participation. A randomized controlled study

IntroductionWhile high participation rates ensure the cost-effectiveness of colorectal cancer screening programs, it is well known that postal requests do not achieve acceptable levels of participation.ObjectiveThis randomized controlled study aimed to test the impact of individualized phone counseling to prompt people aged 50 to 74 to take a colorectal cancer test.MethodTwo phone strategies were compared. The first involved computer-aided individualized counseling while the second was based on motivational interviewing. A total of 49,972 people were randomly assigned to a control group (CG) and to the individualized counseling (IC) and motivational interviewing (MI) telephone groups.ResultsA simple call doubled the participation rate per protocol (19.2% > 9.2%; p < .001; r = .131; OR = 2.374), and tripled it when the interview was conducted (30.4% > 9.2%; p < .001; r = .219; OR = 4.321). In an intention-to-treat analysis, the benefit of calling by phone remained even higher than postal requests (10% > 9.2%; p < .01; r = .014; OR = 1.103). However, there was no impact of the type of interview on participation rates.ConclusionThe results are discussed for future research.