Data Reduction

Feature selection is a valuable technique in data analysis for information-preserving data reduction. This paper describes a feature selection approach for hierarchical clustering based on genetic algorithms using a fitness function that tries to minimize the difference between the dissimilarity matrix of the original feature set and the one of the reduced feature sets. Clustering trees based on reduced feature sets are comparable with those based on the complete feature set. Special measures to favor small reduced feature sets are discussed.

Core strengthening and stability exercises are fundamental for any conditioning training program. Although surface electromyography (sEMG) is used to quantify muscle activity there is a lack of research using this method to investigate the core musculature and core stability. Two types of data reduction are commonly used for sEMG; peak and average rectified EMG methods. Peak EMG has been infrequently reported in the literature with regard to the assessment of core training while even fewer studies have incorporated average rectified EMG data (ARV). The aim of the study was to establish the repeatability of peak and average rectified EMG data during core training exercises and their interrelationship. Ten male highly trained athletes (inter-subject repeatability group; age, 18 ± 1.2 years; height, 176.5 ± 3.2 cm; body mass, 71 ± 4.5 kg) and one female highly trained athlete (intra-subject repeatability group; age; 27 years old; height; 180 cm; weight; 53 kg) performed five maximal voluntary isometric contractions (MVIC) and five core exercises, chosen to represent a range of movement and muscle recruitment patterns. Peak EMG and ARV EMG were calculated for eight core muscles (rectus abdominis, RA; external oblique, EO; internal oblique, IO; multifidis, MF; latissimus dorsi, LD; longissimus, LG; gluteus maximus, GM; rectus femoris, RF) using sEMG. Average coefficient of variation (CV%) for peak EMG across all the exercises and muscles was 45%. This is in comparison to 35% for the ARV method, which was found to be a significant difference (P < 0.05), therefore implying that the ARV method is the more reliable measure for these types of exercise. Analysis of the inter-subject and intra-subject CV% values suggest that these exercises and muscles are sufficiently repeatable using sEMG. Five muscles were highly correlated (R > 0.70; RA, EO, MF, GM, LG) between peak and ARV EMG suggesting, that for these core muscles, the two methods provide a similar evaluation of muscle activity. However, for other muscles (IO, RF, LD) the relationship was found to range from poor to moderate (R = 0.10-0.70). The relationship between peak and ARV EMG was also affected by exercise type. Dynamic low and high-threshold exercises and asymmetrical low-threshold exercises had a moderate correlation between the variables (R = 0.74-0.81), while the static exercise showed a poor correlation (R = 0.46). It can be concluded that there are similarities between the two EMG variables, however due to the effect of type of exercise and muscle on the EMG data, both methods should be included in any future EMG study on the core musculature and core stability exercises.

Background: The Neonatal Behavioral Assessment Scale (NBAS, Brazelton & Nugent, 1995) is an instrument conceived to observe the neonatal neurobehavior. Data analysis is usually performed by organizing items into groups. The most widely used data reduction for the NBAS was developed by . Objective: Examine the psychometric properties of the NBAS items in a sample of 213 Portuguese infants. Method: The NBAS was performed in the first week of infant life (3 days ± 2) and in the seventh week of life (52 days ± 5). Results: Principal component analyses yielded a solution of four components explaining 55.13% of total variance. Construct validity was supported by better neurobehavioral performance of 7-week-old infants compared with 1-week-old infants. Conclusion: Changes in the NBAS structure for the Portuguese sample are suggested compared to Lester factors in order to reach better internal consistency of the scale.

Australia were detcrrnined by ArF (193 mn) excimer laser ablation-ICP-MS with external calibration against a silicate glass standard reference material, NIST 610. The excimer laser beam drilled well-defined pits in both scheelite and silicate glass. With internal standardization against Ca alone, W measurements for the scheelites fall within 5% of the concentrations expected from electron microprobe measurements. A matrix effect between scheelite and silicate glass is apparent in the behaviour of W during laser ablation: W is progressively fractionated from Ca in the glass but not in the scheelite. Proper data reduction, therefore, requires use of the early maximum count rates for W and Ca rather than the mean count rates during ablation. W isotopic ratios measured in the scheelites and an in-house generated silicate glass, ANU 252, are both within N 2.5% of the accepted values for the natural ratios and are reproducible to N 1%, if data for the first _ 11 s of ablation are excluded. Using the same data reduction techniques employed for W, concentrations of Sr, Y, MO, BEE and Pb, present at ppm levels in the scheelites, were measured with a precision of 4% or less. Measurements on Th and U, present at the 5-10 ppb level, and P, Mn, Nb and Ta are less precise (-5-40%) and concentrations of Rb, Zr, Ba, Sn, Hf, Tl and Bi are, for the most part, below detection limits. For Sr, Sm and Nd, replicate ELA-ICP-MS measurements made on 80-pm wide spots in scheelite largely encompass the concentrations determined by ID-TlMS on bulk samples. BEE patterns determined by ELA-ICP-MS for the scheelites vary smoothly as a function of atomic number. Most of the patterns are hump-shaped but others are rather flat except for positive Eu anomalies. This suggests that the hydrothermal fluids that formed the scheelites did not have a common composition and source. 0 1997 Elsevier Science B.V.

Major depressive disorder (MDD) is frequently diagnosed in military personnel returning from deployment. Literature suggests that MDD is associated with a pro-inflammatory state. To the best of our knowledge, no prospective, longitudinal studies on the association between development of depressive symptomatology and cytokine production by peripheral blood leukocytes have been published. The aim of this study was to investigate whether the presence of depressive symptomatology six months after military deployment is ...