Der p 1 is the main allergen of house dust mite Dermatophagoides pteronyssinus, which has routinely been detected in residential dust. However, the procedure for extracting Der p 1 from reservoir dust has not been well defi ned. The aim of this study was to compare Der p 1 mass fractions in dust extracts prepared using the following extraction buffers: phosphate (pH 7.4), borate (pH 8.0), and ammonium bicarbonate (pH 8.0), all with 0.05 % Tween 20. Twenty-eight dust samples were divided into three aliquots and each portion was extracted with one of the three buffers at room temperature. Der p 1 mass fractions were measured in a total of 84 dust extracts using the enzyme immunoassay (range: 0.1 μg g-1 to 7.53 μg g-1). Statistical methods including intraclass correlation showed a high agreement between Der p 1 mass fractions irrespective of the extracting medium. Our results suggest that all three buffers are suitable for the extraction of mite allergens and routine Der p 1 analysis in dust.
This study examined the test-retest reliability, validity and feasibility of the newly developed Dutch Technical-Tactical Tennis Test (D4T). This new test is relevant for talent identification and development in tennis. Thirty-two youth male tennis players (age 13.4 ± 0.5) were classified as elite (n = 15) or sub-elite (n = 17) according to their position on the national youth ranking list under 15 years (cut-off rank 50) in the Netherlands. Games, rallies and different tactical situations (i.e. offensive, neutral and defensive) were simulated with a ball machine. Players had to return 72 balls to predetermined target areas. Stroke quality was recorded based on ball velocity and accuracy (VA-index), as well as percentage errors. Test-retest reliability was assessed by comparing differences between the first and second test-session (n = 10). An intraclass-correlation coefficient of .78 for the VA-index was found (p < .05), indicating excellent test-retest reliability. Independent t-tests revealed that elite players outscored sub-elite players for the VA-index, ball velocity, accuracy and percentage errors (p < .05), supporting good validity. Furthermore, a high correlation was found between the VA-index and individual positions on the youth ranking list (p = -.75; p < .001). The assessment of feasibility indicated that the D4T was applicable for instructors and coaches. In conclusion, the D4T was shown to be a reliable, valid and feasible test to measure technical-tactical characteristics of tennis performance in youth players.
Cronbach’s alpha, alpha if item deleted, item-scale correlations, and item difficulty. Cronbach’s alpha indicates if individual items measure the same concept ( Bühner, 2011 ). To assess four-week test–retest reliability, the two-way random intraclass-correlation coefficient (ICC) 2,1 was calculated for the total score of the DTI-G. A two-way random model was chosen because raters were chosen randomly and answered each of the items ( de Vet et al., 2011 ). Known-groups validity Additionally, known-groups validity was tested based on the duration of clinical experience
, significations; ICC, intraclass-correlation coefficient; CI, confidence interval; SEM, standard error of measurement; SWC, smallest worthwhile change; MDC95%, minimal detectable change at 95% confidence interval The relative and absolute reliability outcomes of the WAnT, SJ, and CMJ are displayed in Table 2 . Excellent relative reliability (ICC > 0.90) was observed for the WAnT, SJ, and CMJ. However, for FI WAnT , HR peakWAnT and RPE WAnT , good relative reliability was shown (ICCs = 0.82, 0.71 and 0.82, respectively). The SEM values for all WAnT variables, the SJ and CMJ