Three-way Analyses Of Variance Research Articles

Surface treatment, liquid, and aging effects on color and surface properties of monolithic ceramics.

The purpose of this study was to investigate the effects of surface treatments, liquids, and aging on color, translucency, and surface properties of monolithic ceramics. Lithium disilicate (LDS) and zirconia-reinforced lithium silicate (ZLS) ceramics (n = 135 each) were cut and divided into three groups [crystallization+glaze (single stage), crystallization-glaze (two stages), and crystallization-polish (two stages)]. One sample from each group was examined using scanning electron microscopy (SEM). Remaining samples were divided into four subgroups (distilled water, coffee, grape juice, and smoothie) (n = 11 each), stored for 12 d in the respective liquids, and thermally aged. One sample from each subgroup was analyzed using SEM. The color, gloss, and roughness values of the samples were analyzed after surface treatment (initial) and storage under different liquids+aging conditions. The initial data and both the aged data and data change values were analyzed using robust two- and three-way analyses of variance. The glazed groups exhibited smoother surfaces. Ceramic type and ceramic-surface treatment interactions affected the initial translucency parameter (TP) (P < .001) and the initial and aged roughness values (P ≤ .001). Surface treatment type affected the color change (P < .001), and ceramic type affected the aged TP values (P < .001). Type of ceramic, surface treatment, and their interactions affected both the initial and aged gloss (P ≤ .001) and TP change values (P ≤ .015). Surface treatment type and ceramic-surface treatment interactions affected the gloss change values (P ≤ .001). Although both ceramics and all surface treatments are clinically applicable, crystallization-glaze is recommended. When gloss and smoothness are important or when translucency is important, ZLS or LDS may be preferred, respectively.

Effect of Prenatal Yoga versus Moderate-Intensity Walking on Cardiorespiratory Adaptation to Acute Psychological Stress: Insights from Non-Invasive Beat-to-Beat Monitoring.

We recently reported enhanced parasympathetic activation at rest throughout pregnancy associated with regular yoga practice. The present study presents a secondary analysis of data collected within a prospective cohort study of 33 pregnant women practicing yoga once weekly throughout pregnancy and 36 controls not involved in formal pregnancy exercise programs. The objective was to assess the impact of prenatal yoga on the autonomic nervous system stress response. Healthy pregnant women with singleton pregnancies were recruited in the first trimester. There was no significant difference in the maternal body mass index (BMI) between the yoga group and the controls (24.06 ± 3.55 vs. 23.74 ± 3.43 kg/m2, p = 0.693). Women practicing yoga were older (28.6 ± 3.9 vs. 31.3 ± 3.5 years, p = 0.005) and more often nulliparous (26 (79%) vs. 18 (50%), p = 0.001). We studied heart rate variability (HRV) parameters in the time domain (SDNN, standard deviation of regular R-R intervals, and RMSSD, square root of mean squared differences of successive R-R intervals) and frequency domain (ln(LF/HF), natural logarithm of low-frequency to high-frequency power), as well as synchronization indices of heart rate, blood pressure and respiration during and immediately following acute psychological stress of a standardized mental challenge test. Measurements were performed once per trimester before and after yoga or a 30 min moderate-intensity walk. Statistical comparison was performed using three-way analyses of variance (p < 0.05 significant). Time domain HRV parameters during and following mental challenge in the yoga group were significantly higher compared to the controls regardless of the trimester (F = 7.22, p = 0.009 for SDNN and F = 9.57, p = 0.003 for RMSSD, respectively). We observed no significant differences in the yoga group vs. the controls in terms of ln(LF/HF) and synchronization indices. Regular prenatal yoga practice was associated with a significantly reduced sympathetic response to mental challenge and quicker recovery after acute psychological stress. These effects persisted throughout pregnancy with regular practice.

Kreativnost i izvedba Simonova zadatka

The aim of this study was to examine performance in the Simon task regarding individual differences in creative behavior measured by The Inventory of Creative Activities and Achievements (ICAA; Diedrich et al., 2018). The study included 105 students and 57 younger working-age individuals (from 19 to 36 years of age). Three-way analyses of variance were carried out on the reaction time in the Simon task given the congruence of the previous and current trials and below/above average results on creative activities and achievements scales. The reaction time in the Simon task was on average shorter in congruent than in incongruent trials (the Simon effect), as well as in the trials preceded by congruent than in those preceded by incongruent trials. The Simon effect was only present in trials preceded by a congruent trial, while reaction times in the trials preceded by incongruent trials were shorter in incongruent than in congruent trials (the Gratton effect). However, neither the Simon nor the Gratton effect were more pronounced within more or less creative participants, but the participants with an above average result on the scale of creative activities reacted on average more slowly than individuals with below the average score. The correlations between the scores on the creativity measures and the different reaction times and indices of the Simon and Gratton effect were not significant. The expected effects related to the Simon task have been obtained in this study, but further research is needed to try to replicate the findings regarding the flexibility of inhibitory control measured by performance in the Simon task and creative behavior.

Effect of whitening concepts on surface roughness and optical characteristics of resin-based composites: An AFM study.

The aim of this study was to evaluate the effects of various whitening agents on the surface roughness and optical characteristics of different types of resin composite restorations. Fifty specimens were prepared for each resin [G-aenial Posterior (GP), SonicFill-2 (SF), Solidex (SDX), and Nova Compo HF (NC)]. Following baseline color and surface roughness (Ra) measurements, the specimens were randomly divided into 5 groups (n = 10/group) according to whitening concepts: control (distilled water), in-office bleaching [OB-(Opalescence Boost)], at-home bleaching [HB-(Opalescence PF)], whitening toothpaste [WT-(Signal White Now)], and whitening mouthwash [WM-(Listerine Advanced White)]. ∆E00 , ∆TP00 , and ∆WID values were calculated before and after the whitening procedure with a spectrophotometer using the CIEDE2000 formula. Surface roughness measurements were repeated. The surface topography was determined using atomic force microscopy. Two- and three-way analyses of variance and Tukey's post-hoc test were performed, with p < 0.05 regarded as indicative of significance. No significant differences were detected among the resin composite materials in terms of the ΔE00 values (p > 0.05). Color change of all resin materials was above the AT threshold (>1.8) and the PT threshold (>0.8). All restorative materials presented acceptable (AT<2.62) TP00 values. Solidex specimens demonstrated the lowest WID values compared to the other composites. There were significant differences among the whitening procedures with respect to ΔE00 , ΔTP00 , and WID values (p < 0.001). SF/WT combination showed the highest and clinically unacceptable ΔE00 values. The highest roughness values were observed in the SDX specimens and the combination of SDX/OB. The effect of whitening agents on the optical characteristics and surface roughness of restorative materials depends on the type of material, agent, and time. RESEARCH HIGHLIGHTS: Clinicians should be aware that long-term use of over-the-counter products due to the abrasive effects of their ingredients and repeated bleaching session applications may affect the color stability and surface roughness of resin composites.

The effect of bleaching applications on stained bulk-fill resin composites

BackgroundThe structure of bulk-fill resin composites differs from that of their conventional counterparts, but how this difference affects the color stability of the former after staining and bleaching is unclear. Accordingly, this study was aimed at investigating color change in nine bulk-fill resin composites and one nanohybrid resin composite treated with hydrogen peroxide and carbamide peroxide after staining with tea, coffee, and red wine.MethodsEighty specimens were prepared from each resins [Clearfil Majesty Posterior (CMP), SDR flow+ (SDR), FiltekTMBulk-Fill Flowable Restorative (FBF), Reveal HD Bulk (RHD), Beautifil-Bulk Restorative (BBR), Tetric EvoCeram® Bulk Fill (TEC), SonicFill™2 (SF2), everX Posterior™ (eXP), X-tra base (XB), and Venus® Bulk Fill (VBF)]. Following baseline color measurements, the specimens were randomly divided into 4 groups according to immersion solutions and distilled water as the control. At the end of a 30-day test period, color measurements were repeated, and color change values (∆E00) were calculated. Each resin group was then divided into 2 subgroups (with 10 specimens per group) on the basis of bleaching agent (Opalescence Boost 40%, Opalescence PF 16%). Following bleaching application, ∆E00 and changes of whiteness (∆WID1 = WIDbleaching-WIDbaseline, ΔWID2 = WIDbleaching-WIDstaining) values were recorded. Two- and three-way analyses of variance and Tukey’s post hoc test were performed, with a P < 0.05 regarded as indicative of significance.ResultsAfter immersion in distilled water, tea, and red wine, the highest ΔE00 values were observed in eXP (P < 0.05). Resin materials immersed in coffee and tea exhibited statistically higher ∆E00 values than those immersed in red wine except for eXP, TEC, and FBF (P < 0.05). For eXP, the highest ∆E00 values were recorded in distilled water. For TEC and FBF, there was no statistically significant difference among the immersion solutions and distilled water (P > 0.05). For all the resins and staining beverages, no statistically significant difference in ∆WID1 and ∆WID2 values were detected between bleaching agents (P > 0.05). All the ΔWID1 values were above the whiteness perceptibility threshold.ConclusionThe bulk-fill materials were more resistant to discoloration and bleaching procedures than the conventional resin composites. Coffee and tea caused more staining than distilled water and red wine generally. The type of bleaching procedure had no effect on the whiteness of the tested materials.

Influence of pH Cycling on Erosive Wear and Color Stability of High-Viscosity Glass Ionomer Cements.

The purpose of this in vitro study was to evaluate erosive wear and change in color of high-viscosity glass ionomer cements after pH cycling in two erosive media. There were 3 experimental groups with 22 samples each, (I) EQUIA Forte HT without coat, (II) Fuji IX and (III) Ketac Universal Aplicap. Each group was randomly divided into three subgroups (n = 6–8) further exposed to different environments, (1) distilled water, (2) green tea (pH 3.78) and (3) Aceto balsamico vinegar (pH 3.0). Mass and L* a* b* values were recorded before and after pH cycling. The samples in subgroups 2 and 3 were exposed to the acidic media two times a day for 10 min, over a period of 14 days. The differences among materials and erosive effects of the three media were tested using three-way analyses of variance with post hoc LSD test at the significance level p < 0.05. The effect of pH cycling in Aceto balsamico and green tea was degrading for all three materials. pH cycling in Aceto balsamico caused significantly higher erosive wear than pH cycling in Fuzetea and storage in distilled water, in all materials (p < 0.05). pH cycling in both acidic media and in the control group resulted in a significant change in L* a* and b* (p < 0.05). The L* value decreased significantly and the a* and b* values increased significantly (p < 0.05).

The Effect of Elementary School Soccer Instruction Using Virtual Reality Technologies on Students’ Attitudes toward Physical Education and Flow in Class

We analyzed the effects of an elementary school soccer class using virtual reality technology on students’ attitudes toward physical education class and the influence on class flow. The data from 113 elementary school students from Seoul and Gyeonggi-do were analyzed. Students were divided into groups that received either virtual reality or traditional classes (e.g., playing on a playground). Data were analyzed with three-way analyses of variance. Results revealed that students who participated in the virtual reality classes had more confidence, concentration, and experienced more flow (specifically, attention to PE class, integration of ability, challenge, and sense of control) than students who participated in the traditional class. This suggests that virtual reality technology positively affected students’ attitudes and flow. In subsequent research, it is necessary to develop and disseminate a variety of virtual reality sports programs and to conduct studies with students from various grade levels.

The Effect of Background Noise on Immediate Free Recall of Words in Younger and Older Listeners with Hearing Loss.

Auditory working memory is a crucial factor for complex cognitive tasks such as speech-in-noise understanding because speech communication in noise engages multiple auditory and cognitive capacities to encode, store, and retrieve information. An immediate free recall task of words has been used frequently as a measure of auditory working memory capacity. The present study investigated performance on the immediate free recall of words in quiet and noisy conditions for hearing-impaired listeners. Fifty hearing-impaired listeners (30 younger and 20 older) participated in this study. Lists of 10 phonetically and lexically balanced words were presented with a fixed presentation rate in quiet and noise conditions. Target words were presented at an individually determined most comfortable level (MCL). Participants were required to recall as many of the words in an arbitrary order immediately after the end of the list. Serial position curves were determined from the accuracy of free recall as a function of the word position in the sequence. Three-way analyses of variance with repeated measures were conducted on the percent-correct word recall scores, with two independent within-group factors (serial position and listening condition) and a between-group factor (younger, older). A traditional serial position curve was found in hearing-impaired listeners, yet the serial position effects depended on the listening condition. In quiet, the listeners with hearing loss were likely to recall more words from the initial and final positions compared with the middle-position words. In multi-talker babble noise, more difficulties were observed when recalling the words in the initial position compared with the words in the final position. Without a noise, a traditional U-shaped serial position curve consisting of primacy and recency effects was observed from hearing-impaired listeners, in accord with previous findings from normal-hearing listeners. The adverse impact of background noise was more pronounced in the primacy effect than in the recency effect.

Influence of CAD/CAM Material and Preparation Design on the Long-term Fracture Resistance of Endocrowns Restoring Maxillary Premolars

Objective: To evaluate the effect of different occlusal preparation designs and CAD/CAM materials on the fracture resistance of maxillary premolars endcrowns. Materials and Methods: sixty-four endodontically treated upper first premolars were randomly divided into four groups according to ceramic materials (Vita Enamic and IPS emax CAD) and occlusal preparation designs (Anatomical and horizontal butt joint). After teeth preparation, the restorations were all made by CAD/CAM system (Cerec MCXL). Half of each group had undergone cyclic fatigue testing of 105 cycles with 50N loading force at a frequency of 0.5Hz in a mechatronic chewing simulator machine, and then all samples were loaded to fracture using a universal testing machine with a cross head speed of 0.5mm/min recording the fracture resistance values in N . The specimens were measured and statistically analyzed using using three-way analyses of variance (ANOVA), followed by serial two-way and one-way ANOVAs at each level of the study. P-values were adjusted for multiple comparisons using BENFORRONI correction and the significance level was set at P ? 0.05 for all tests. Results: Vita Enamic endocrowns showed higher fracture resistance values than IPS e max specimens. Conclusions: Vita Enamic endocrowns with anatomical preparations were found to be more favourable restoring endodontically treated maxillary premolars. KEYWORDSEndocrowns; All-Ceramic; Fracture; Cyclic loading; CAD/CAM

Effect of Simulated Pulpal Microcirculation on Temperature When Light Curing Bulk Fill Composites.

To evaluate the effect of light curing bulk fill resin composite restorations on the increase in the temperature of the pulp chamber both with and without a simulated pulpal fluid flow. Forty extracted human molars received a flat occlusal cavity, leaving approximately 2 mm of dentin over the pulp. The teeth were restored using a self-etch adhesive system (Clearfil SE Bond, Kuraray) and two different bulk fill resin composites: a flowable (SDR, Dentsply) and a regular paste (AURA, SDI) bulk fill. The adhesive was light cured for 20 seconds, SDR was light cured for 20 seconds, and AURA was light cured for 40 seconds using the Bluephase G2 (Ivoclar Vivadent) or the VALO Cordless (Ultradent) in the standard output power mode. The degree of conversion (DC) at the top and bottom of the bulk fill resin composite was assessed using Fourier-Transform Infra Red spectroscopy. The temperature in the pulp chamber when light curing the adhesive system and resin composite was measured using a J-type thermocouple both with and without the presence of a simulated microcirculation of 1.0-1.4 mL/min. Data were analyzed using Student t-tests and two-way and three-way analyses of variance (α=0.05 significance level). The irradiance delivered by the light-curing units (LCUs) was greatest close to the top sensor of the MARC resin calibrator (BlueLight Analytics) and lowest after passing through the 4.0 mm of resin composite plus 2.0 mm of dentin. In general, the Bluephase G2 delivered a higher irradiance than did the VALO Cordless. The resin composite, LCU, and region all influenced the degree of cure. The simulated pulpal microcirculation significantly reduced the temperature increase. The greatest temperature rise occurred when the adhesive system was light cured. The Bluephase G2 produced a rise of 6°C, and the VALO Cordless produced a lower temperature change (4°C) when light curing the adhesive system for 20 seconds without pulpal microcirculation. Light curing SDR produced the greatest exothermic reaction. Using simulated pulpal microcirculation resulted in lower temperature increases. The flowable composite (SDR) allowed more light transmission and had a higher degree of conversion than did the regular paste (AURA). The greatest temperature rise occurred when light curing the adhesive system alone.

Evaluation of the sensory roughness of some coated wood surfaces by image analysis

Sensory roughness is one of the most important factors that determines the quality and/or value of various wood products. The aim of the present study was to confirm whether the sensory roughness of coated wood surfaces could be estimated by the here proposed image analysis. Twelve white oak (Quercus alba) fancy veneer overlaid plywood samples were prepared with two types of grains and six coating specifications. Forty participants subjectively evaluated the sensory roughness of the samples by rubbing their surfaces without being able to see them. Sample surface images were acquired with a goniophotometric method and were submitted to an image analysis to calculate lightness differences (contrast) between relatively small areas as image characteristics. Three surface profile parameters were also measured based on the conventional stylus method. Three-way analyses of variance for the evaluation of sensory roughness revealed significant main effects of the coating specification and the rubbing direction. Although contrast and surface profile parameters were hard to estimate in terms of sensory roughness for spiny surfaces, both measures were well correlated to sensory roughness for porous surfaces. In particular, the linearity between the sensory roughness of the porous surfaces and contrast was equal to or greater than that of the surface profile parameters.

Assessing the importance of environmental factors to phytoliths of Phragmites communis in north-eastern China

Phytoliths have proved to be reliable indicators of environmental conditions both at present and in the past, and can provide evidence for the distribution of taxa or vegetation. Understanding the environmental significance of phytoliths within plants helps in drawing more reliable inferences about palaeovegetation and in reconstructing the palaeo-environment. The present study examined the relationship between phytoliths and environmental factors to assess the environmental significance of different types of phytoliths. Phytoliths were extracted from Phragmites communis growing in xerophytic and aquatic habitats at twelve sampling sites in north-eastern China and their implications for the environment were assessed using quantitative data mainly including phytolith concentration and environmental factors and statistical analyses. Principal component analysis (PCA) of several environmental factors (including the climate, micro terrain, and the physicochemical properties of soils) revealed that other factors being constant, P. communis phytolith concentrations were influenced largely by the average annual temperature and precipitation. Orthogonal experiment analysis and three-way analyses of variance of the concentrations confirmed the reliability of the results of the PCA. More specifically, the concentrations of the saddle and rondel types of phytoliths (the short-cell phytoliths) were closely linked to the average annual temperature whereas those of the elongate, lanceolate, and bulliform phytoliths (the non-short-cell phytoliths) were more sensitive to the variations in water status. The results contribute to further confirming the major environmental implications of phytoliths and, in turn, providing a reference for growth and development of wetland plants. Our findings also provide critical information that could help managers and policymakers assess and modify ecological restoration practices.

Response of phytoliths in Phragmites australis to environmental factors in northeast China

Accuracy of paleovegetation reconstruction and understanding of phytolith formation would both be improved by further study of phytolith size in the Phragmites australis under different environmental conditions. Leaves of P. australis were collected from 11 sampling sites in northeast China with differences in temperature, precipitation and habitat. Principal component analysis of environmental factors (climatic and edaphic) indicated that the annual averages of temperature and precipitation were the main factors influencing phytolith size. Moreover, three-way analyses of variance (ANOVAs) further showed that phytolith size differed significantly under conditions of different temperature or precipitation gradients, whereas habitat differences had little effect. The changes in phytolith size with temperature differed in the humid, semi-humid and semi-arid areas of northeast China. In the humid and semi-humid areas, moving from the temperate to the warm temperate zone, increasing temperature reduced phytolith size; whereas in the semi-arid area, phytolith became larger with increasing temperature. In the warm temperate and temperate zones, the changes of phytolith size with precipitation showed the same trend—moving from the semi-arid to semi-humid to humid areas, as precipitation increased, phytolith grew larger. Finally, ANOVA revealed that phytoliths were also sensitive to habitat. These findings demonstrated that the size of P. australis phytoliths was sensitive to environmental factors: for regional research, the annual averages of temperature and precipitation were the major factors influencing size, but in the same climate district, habitat differences seemed to also have a significant impact on phytolith size. Consequently, phytolith analysis has potential utility in the study of global climate change, palaeoenvironment reconstruction, and environmental conservation and restoration.

The effects of light curing units and environmental temperatures on C = C conversion of commercial and experimental bonding agents.

Polymerization of bonding agents (BA) is a critical factor in determining the success of bonded restorations. We aimed to assess the effects of two light curing units and two temperatures on the extent of polymerization (EP) of a commercial BA and an experimental BA. Forty BA specimens were randomly divided into 8 subgroups of n=5 to compare the polymerization of two BAs (experimental/Scotchbond) based on the variables: temperature (23/37°C) and light-curing unit (quartz-tungsten-halogen/light-emitting diode). The EP (%) was measured using differential scanning calorimetry, and analyzed using the t-test, two- and three-way analyses of variance (ANOVA), and the Bonferroni test (α=0.05). There were significant differences between the EP results between the two BAs (P=0.012) and due to the different temperatures (P=0.001), but not between the different light-curing units (P=0.548). The interaction between BA and temperature was significant (P<0.001). The other interactions were nonsignificant. The two light-curing units had similar effects on the EP. The EP values were better when curing was performed at human body temperature.

Screening for Autism in Mexico

In order to conduct the screening phase of the first epidemiological survey of autism spectrum disorders (ASDs) in Mexico, we needed a screening tool to detect autistic symptomatology in a large sample of school-age children. We used the Spanish version of the Social Responsiveness Scale (SRS). We recruited a clinical sample of 200 children (81% males; mean age: 7.4 years) with a confirmed diagnosis of ASDs and a sample of 363 control children (59.5% males; mean age: 8.5 years) without ASDs. Three-way analyses of variance (ANOVAs) identified a main effect of clinical status (ASDs vs. controls) for both parent and teacher scales, but no gender or age effect. The mean total and subscale raw scores were significantly different between the clinical and control groups for the parent and for the teacher SRS (P < 0.001). The internal consistency of the SRS was excellent. Receiver operating characteristic (ROC) analyses showed excellent discriminant validity of the SRS in the Mexican sample (area under the curve: 0.962 for the parent, 0.960 for the teacher). ROC curves were also used to determine which cutoff would provide the best trade-off between sensitivity and specificity. Mexican SRS scores were significantly higher than in the U.S. and German population for typically developing children but comparable for clinically referred subjects. The SRS is an acceptable screening instrument for epidemiological studies of ASDs in Mexico. Its psychometric properties are excellent and comparable to those derived from North American and other samples.

Distribution of Health-Related Physical Fitness in Texas Youth

This study examined demographic and geographic variability in aggregated school-level data on the percentage of students achieving the FITNESSGRAM® Healthy Fitness Zones™ (HFZ). Three-way analyses of variance were used to examine differences in fitness achievement rates among schools that had distinct diversity and socioeconomic status profiles. The results revealed age-related declines in the percentage of youth who achieved the HFZ standard for cardiovascular fitness (elementary school: 70%; middle school: 46%; high school: 34%). Interestingly, there was little evidence of age-related declines in other fitness dimensions. Schoollevel attainment of fitness was consistently higher in schools categorized as low diversity and high socioeconomic status. Clear spatial patterns in fitness achievement were also evident when data were analyzed at the region and county level using geodemographic information system software.

Culture, management accounting and managerial performance: Focus Iran

Abstract Modern management and control systems may not be equally effective in every country. Budget participation is one of the effective tools in western nations. However, management control tools, in general, and budget participation, in particular, could be ineffective or even dysfunctional in other environments. Hofstede (1980) had suggested that cultural differences among countries are influencing factors. In this study, we investigate the impact of culture, budgetary participation, and management accounting systems on managerial performance in Iran. Three-way analyses of variance are used separately for each of the four cultural Hofstede dimensions. We find convincing evidence that the application of management tools and techniques developed in western countries for effective management performance is not as useful in the Iranian context.

Influence of halogen irradiance on short- and long-term wear resistance of resin-based composite materials

Objective The Oregon Health Science University (OHSU) four-chamber oral wear simulator was used to examine the impact of halogen irradiance on the short- and long-term wear behavior of four-methacrylate resin-based composites (RBCs). The hypothesis proposed was that exacerbated wear would occur following the long-term wear of RBCs irradiated under non-optimized irradiance conditions. Methods Disc-shaped specimens (12.0 ± 0.1 mm diameter and 2.0 ± 0.1 mm height) of each RBC were prepared at irradiances of 650 ± 14, 530 ± 8, 420 ± 14, 350 ± 8, 270 ± 8, 230 ± 14, 190 ± 8, and 150 ± 8 mW/cm 2, respectively. Short-term three-body wear simulation was carried out for 50,000 cycles and long-term was performed up to 500,000 cycles. The wear facets were analyzed using a non-contact optical profilometer. One-, two-, and three-way analyses of variance (ANOVA) were made at P = 0.05, guided as necessary by Tukeys correction in multiple partial analyses of the mean total volumetric wear and mean maximum wear depth. Results For the short-term wear resistance, the two-way ANOVA identified no significant difference in the mean total volumetric wear ( P = 0.188) although the mean total wear depth was identified to be significant ( P = 0.024). The long-term wear resistance for the mean total volumetric wear identified significant differences for each RBC at varying irradiances with the number of cycles but not for the mean maximum wear depth. Significance The increased number of ploughing actions of the antagonist on the RBC (long-term) results in increased friction which would be expected to play a major role in the wear process. The significant increase in the mean total volumetric wear, but not the mean maximum wear depth, observed over time which is exacerbated at reduced halogen irradiances emphasizes the arguments of DeLong for the employment of volume for evaluating material loss due to wear following in vitro wear simulation of RBCs.

Enrollment in Physical Education Is Associated With Overall Physical Activity in Adolescent Girls

Little is known about population-level contributions of school physical education to overall physical activity (PA) in youth. Because PA levels are lower in girls than boys, it is particularly important that the effects of PE programs in adolescent girls be understood. Thus, the purpose of this study was to determine the association of enrollment in physical education and overall physical activity participation in adolescent girls. A measurement protocol was administered to cross-sectional samples of 8th-, 9th-, and 12th-grade girls participating in a school-based PA intervention study (1998–2003). PA was assessed with the 3-Day Physical Activity Recall. Three-way analyses of variance were performed to compare groups formed on the basis of physical education enrollment. For each grade group of girls, those who were enrolled in physical education reported more moderate-to-vigorous PA and more vigorous PA than nonenrolled girls. When activity in physical education classes was deleted, 8th-and 9th-grade physical education enrollees were not more active than nonenrollees; however, 12th-grade physical education enrollees remained more active than nonenrollees. Girls who were enrolled in physical education were more physically active than nonenrolled girls in all three grade levels. These findings suggest that expanded enrollment in physical education may increase American adolescent girls' PA level.

Enrollment in Physical Education Is Associated With Overall Physical Activity in Adolescent Girls

Little is known about population-level contributions of school physical education to overall physical activity (PA) in youth. Because PA levels are lower in girls than boys, it is particularly important that the effects of PE programs in adolescent girls be understood. Thus, the purpose of this study was to determine the association of enrollment in physical education and overall physical activity participation in adolescent girls. A measurement protocol was administered to cross-sectional samples of 8th-, 9th-, and 12th-grade girls participating in a school-based PA intervention study (1998–2003). PA was assessed with the 3-Day Physical Activity Recall. Three-way analyses of variance were performed to compare groups formed on the basis of physical education enrollment. For each grade group of girls, those who were enrolled in physical education reported more moderate-to-vigorous PA and more vigorous PA than nonenrolled girls. When activity in physical education classes was deleted, 8th-and 9th-grade physical education enrollees were not more active than nonenrollees; however, 12th-grade physical education enrollees remained more active than nonenrollees. Girls who were enrolled in physical education were more physically active than nonenrolled girls in all three grade levels. These findings suggest that expanded enrollment in physical education may increase American adolescent girls' PA level.