Rate Of Change In Performance Research Articles

The Influence of Birth Cohorts on Future Cognitive Decline.

Slowed rates of cognitive decline have been reported in individuals with higher cognitive reserve (CR), but interindividual discrepancies remain unexplained. Few studies have reported a birth cohort effect, favoring later-born individuals, but these studies remain scarce. We aimed to predict cognitive decline in older adults using birth cohorts and CR. Within the Alzheimer's Disease Neuroimaging Initiative, 1,041 dementia-free participants were assessed on four cognitive domains (verbal episodic memory; language and semantic memory; attention; executive functions) at each follow-up visit up to 14 years. Four birth cohorts were formed according to the major historical events of the 20th century (1916-1928; 1929-1938; 1939-1945; 1946-1962). CR was operationalized by merging education, complexity of occupation, and verbal IQ. We used linear mixed-effect models to evaluate the effects of CR and birth cohorts on rate of performance change over time. Age at baseline, baseline structural brain health (total brain and total white matter hyperintensities volumes), and baseline vascular risk factors burden were used as covariates. CR was only associated with slower decline in verbal episodic memory. However, more recent birth cohorts predicted slower annual cognitive decline in all domains, except for executive functions. This effect increased as the birth cohort became more recent. We found that both CR and birth cohorts influence future cognitive decline, which has strong public policy implications.

Effects of extended days on feed on rate of change in performance and carcass characteristics of feedlot steers and heifers and Holstein steers

We analyzed data from feedlot studies in which beef steers and heifers and Holstein steers were fed for extended days beyond the typical slaughter date with the objective of determining the rate of change in selected performance and carcass measurements over the extended feeding periods. Performance and carcass measurements from 7 experiments with beef steers, 6 experiments with beef heifers, and 2 experiments with Holstein steers, representing a total of 687 pen observa- tions, were analyzed. Cattle were fed high-grain diets and managed under industry-standard conditions. All experi- ments included extended days on feed as a factor (0- to 62-d range for steers; 0- to 42-d range for heifers; and 0- to 56-d range for Holsteins), and several experiments included β-agonist and implant program comparisons. Key variables analyzed included DMI, ADG, final shrunk BW, hot carcass weight, and various measures of carcass fatness, yield, and quality. Mixed-model statistical meth- ods were used to evaluate β-agonist and implant programs and their interaction with extended days on feed, as well as the overall rate of change in performance and carcass measurements with extended days on feed, adjusting for random intercept effects of studies. Feeding control diets versus zilpaterol (2 steer studies) or ractopamine diets (2 steer studies) resulted in effects consistent with the published literature. Interactions between extended days on feed and β-agonist or implant program treatments were noted for less than 5% of the variables examined. Similarly, for the overall analyses within class of cattle, interactions between extended days on feed and dietary or implant treatments were rare (2.5% of variables evaluated). Slope values in the overall analyses for all 3 classes of cattle were generally significant (P ≤ 0.03 for 85% of the variables analyzed), reflecting increased final shrunk BW and hot carcass weight, greater carcass fatness, and shifts toward higher QG and YG with extended days on feed. Producers selling cattle on a carcass basis could use our slope data to es- timate changes in carcass weight with extended days on feed, as well as potential premiums and discounts that could be used in profit–loss projections.

Minimal decrease in triathlon running performance compared to isolated running performance is important for sprint triathlon success

A strategy to improve running performance at the end of a triathlon (TR) is minimizing fatigue from the preceding exercise. However, little is known about decrease in TR compared to isolated running (IR) performance and the degree at which it changes. This study examined the decrease in TR performance compared with IR performance and the degree of change in the sprint triathlon competition results. We searched the web (http://www.jtu.or.jp/) for the official result times of certification competitive events from 2013 to 2016 of the Japan Triathlon Union and elite categories participating in the Asia Cup Osaka sprint triathlon from 2013 to 2016 of the International Triathlon Union. Data of 236 athletes who finished IR and TR in the same year were analyzed. The average time was significantly longer in TR than in IR and the effect size was large, regardless of competition years and sex (p < 0.01). The IR time variation (coefficient of variation) was 3.7?8.2%, while the rate of change in performance variation was 35.6?95.0%. The overall triathlon time and the rate of change in performance were significantly correlated (Speaman?rs = 0.47?0.76, p < 0.05). TR performance was lower than the IR performance and the degree varied widely among individuals. For elite triathletes who have homogeneous IR performance, a minimal decrease in TR compared to IR performance effectively increases sprint triathlon success.

Developmental pathways of cardiorespiratory fitness from 6 to 15 years of age

Most of the information gathered about physical fitness of paediatric populations are cross-sectional, resulting in normative perspectives that account for average values relative to age, but not to a comprehensive understanding of developmental individual trajectories. The aim of this study was to model the longitudinal development of cardiorespiratory fitness of boys and girls from 6 to 15 years of age, using an individual centred approach. Two hundred twenty-nine school children (128 boys; 101 girls) were followed on their 20 metres shuttle run test (20mSRT) results from 6 to 15 years of age. Annual measurements were made during the four years of primary school, and again at grade 9th or 10th. Individual trajectories of 20mSRT development were modelled and grouped according to their similarities of change in three different developmental pathways that were included in subsequent hierarchical nested models for testing each sex developmental model of cardiorespiratory fitness. Final models including the developmental pathways showed better deviance statistics (p < .001). Interindividual slope variances were almost zero, and statistically non-significant (0.05 boys 0.01 girls; p > .50), meaning these models capture well the existing variability, in respect to the rate of change. Individual pathways of change in the performance of 20mSRT test can be detected in childhood and adolescence. Additionally, all individual’s developmental trajectories in 20mSRT can be described using three significantly different slopes. These pathways are indicative of a high, average, or low rate of change in performance over the years and differ from the normative approach.

Rate Of Performance Change In American Female Weightlifters Over Ten Years Of Competition

Rate Of Performance Change In American Female Weightlifters Over Ten Years Of Competition

Effects of age on marathon finishing time among male amateur runners in Stockholm Marathon 1979–2014

PurposeThe purpose of the present study was to investigate the age-related changes in the endurance performance among male amateur marathon runners. MethodsSubjects were taken from the 36 Stockholm Marathons held from 1979 through 2014, and age and finishing time were analyzed for a total of 312,342 male runners. ResultsThe relation was found to be a second-order polynomial, t = a + bx + cx2, which models 99.7% of the variation in the average running time t as a function of age x. The model shows that the marathon performance of the average runner improves up to age 34.3 ± 2.6 years, thereafter, the performance starts to decline. A quantification of the age's influence on running time shows that it accounts for 4.5% of the total variance seen in the performance data. ConclusionThese outcomes indicate that the effect of age on performance in endurance running events is clearly measurable, quantifiable, and possible to describe. At the same time the findings indicate that other factors, such as training, affect the performance more. A comparison with the elite showed peak performance at the same age, but the rates of change in performance with age, improvement as well as degradation, was found to be higher among the elite.

Early adolescent cognitive gains are marked by increased sleep EEG coherence.

Although the increases in cognitive capacities of adolescent humans are concurrent with significant cortical restructuring, functional associations between these phenomena are unclear. We examined the association between cortical development, as measured by the sleep EEG, and cognitive performance in a sample of 9/10 year olds followed up 1 to 3 years later. Our cognitive measures included a response inhibition task (Stroop), an executive control task (Trail Making), and a verbal fluency task (FAS). We correlated sleep EEG measures of power and intra-hemispheric coherence at the initial assessment with performance at that assessment. In addition we correlated the rate of change across assessments in sleep EEG measures with the rate of change in performance. We found no correlation between sleep EEG power and performance on cognitive tasks for the initial assessment. In contrast, we found a significant correlation of the rate of change in intra-hemispheric coherence for the sigma band (11 to 16 Hz) with rate of change in performance on the Stroop (r = 0.61; p<0.02) and Trail Making (r = −0.51; p<0.02) but no association for the FAS. Thus, plastic changes in connectivity (i.e., sleep EEG coherence) were associated with improvement in complex cognitive function.

Patterns of change in nonverbal cognition in adolescents with Down syndrome.

This study was designed to examine longitudinal change in nonverbal cognitive abilities across adolescence for 20 males with Down syndrome (DS). We used hierarchical linear modeling to examine the rate of change in performance on the subtests of the Leiter-R Brief IQ across four annual time points and to determine the relation between maternal IQ and level and rate of change in performance. Results indicated no significant change in IQ (standard scores) with age in the sample, suggesting IQ stability during adolescence for individuals with DS, although several participants performed at floor level on the standard scores for the Leiter-R, limiting interpretation. Growth scores, however, provide a metric of absolute ability level, allow for the examination of change in Leiter-R performance in all participants, and minimize floor effects. Results from the analysis of growth scores indicated significant gain in absolute nonverbal cognitive ability levels (growth score values) over time for the adolescents with DS, although the growth varied by subdomain. Maternal IQ did not explain variability in cognitive performance or change in that performance over time in our sample of adolescents with DS.

Adjusting to new work teams: Testing work experience as a multidimensional resource for newcomers

Summary The successful performance adjustment of team newcomers is an increasingly important consideration given the prevalence of job-changing and the uncertainty associated with starting work in a new team setting. Consequently, using sensemaking and uncertainty reduction theories as a conceptual basis, the present study tested work experience as a potential resource for newcomer performance adjustment in teams. Specifically, we tested work experience as a multidimensional predictor of both initial newcomer performance and the rate of performance change after team entry. We tested hypotheses using longitudinal newcomer performance data in the context of professional basketball teams. Although the traditional quantitative indicators of the length and amount of work experience were not meaningfully associated with newcomer performance adjustment, their interaction was. In addition, the qualitative indicator of newcomers' past transition experience revealed a significant, positive association with the rate of newcomer performance improvement following team entry. These results suggest that work experience is a meaningful facilitator of newcomer adjustment in teams and emphasize the dual consideration of both quantitative and qualitative work experiences. The theoretical and practical implications of these findings are discussed. Copyright © 2013 John Wiley & Sons, Ltd.

Faster on easy items, more accurate on difficult ones: Cognitive ability and performance on a task of varying difficulty

Using more complex items than those commonly employed within the information-processing approach, but still easier than those used in intelligence tests, this study analyzed how the association between processing speed and accuracy level changes as the difficulty of the items increases. The study involved measuring cognitive ability using Raven's Advanced Progressive Matrices and examining changes in the accuracy–ability and speed–ability correlations due to the increasing difficulty of the items. As expected, high-ability individuals demonstrated a higher accuracy rate and faster performance than low-ability individuals. The accuracy–ability association became stronger as the item difficulty increased. The speed–ability correlations tended to decrease in absolute values as the item difficulty increased, although this trend, when formally examined, was non-significant.For a more precise analysis, the entire variance of each response time and accuracy was decomposed into the components that described constancy in performance over difficulty levels and the rate of change in performance caused by increasing task difficulty. Estimating these components for both response latencies and accuracy scores within the same latent growth model demonstrated that the speed–accuracy correlation was evident only for baseline performance; the rate of slowing with increasing task difficulty was not correlated with the respective rate of change in accuracy level. High-ability participants differed from low-ability participants in the speed (not accuracy) of baseline performance and in the rate of difficulty-related change in accuracy (not in processing speed).

Predicting late-life disability and death by the rate of decline in physical performance measures

the rate of performance decline may influence the risk of disability or death. for 4,182 Cardiovascular Health Study participants, we used multinomial Poisson log-linear models to assess the contribution of physical performance in 1998-99, and the rate of performance change between 1992-93 and 1998-99, to the risk of death or disability in 2005-06 in three domains: mobility, upper-extremity function (UEF) and activities of daily living (ADL). We evaluated performance in finger-tapping, grip strength, stride length, gait speed and chair stands separately and together for each outcome, adjusting for age, gender, race and years of disability in that outcome between 1992-93 and 1998-99. participants' age averaged 79.4 in 1998-99; 1,901 died over 7 years. Compared with the lowest change quintile in stride length, the highest quintile had a 1.32 relative risk (RR) of ADL disability (95% CI: 1.16 -1.96) and a 1.27 RR of death (95% CI: 1.07 -1.51). The highest change quintile for grip strength increased the risk of ADL disability by 35% (95% CI: 1.13 -1.61) and death by 31% (95% CI: 1.16 -1.49), compared with the lowest quintile. The annual change in stride length and grip strength also predicted disability in mobility and UEF. performance trajectories independently predict death and disability.

Correlates of social problem solving during the first year after traumatic brain injury in children.

Effects of pediatric traumatic brain injury (TBI) on social problem-solving were examined in a longitudinal study of 103 children with moderate-to-severe TBI (n = 52) or orthopedic injury (OI; n = 51) using the Interpersonal Negotiation Strategies task (INS). Children solved age-appropriate hypothetical social conflicts, with responses for four problem-solving steps scored by developmental level. The OI group performed better than the TBI group, but rate of change in performance over time did not differ between groups, suggesting improvement in children with TBI was not due to recovery from injury. Strong relations between INS performance and memory and language skills emerged, but emotional processing was only weakly related to INS performance. Frontal focal lesions influenced INS performance in younger (but not older) children with TBI. Diffusion tensor imaging (DTI), revealed strong relationships between the INS and increased apparent diffusion coefficient (ADC) measures indexing connectivity in the dorsolateral and cingulate regions in both TBI and OI groups, and in the temporal and parietal regions in the TBI group. These findings inform studies of social problem-solving skills during the first year post TBI. (PsycINFO Database Record (c) 2008 APA, all rights reserved).

A Multilevel Modeling Approach to Examining Individual Differences in Skill Acquisition for a Computer-Based Task

This article explores the role of age, cognitive abilities, prior experience, and knowledge in skill acquisition for a computer-based simulated customer service task. Fifty-two participants aged 50-80 performed the task over 4 consecutive days following training. They also completed a battery that assessed prior computer experience and cognitive abilities. The data indicated that overall quality and efficiency of performance improved with practice. The predictors of initial level of performance and rate of change in performance varied according to the performance parameter assessed. Age and fluid intelligence predicted initial level and rate of improvement in overall quality, whereas crystallized intelligence and age predicted initial e-mail processing time, and crystallized intelligence predicted rate of change in e-mail processing time over days. We discuss the implications of these findings for the design of intervention strategies.

Qualitative and quantitative change in the dynamics of motor learning.

The experiments examined qualitative and quantitative changes in the dynamics of learning a novel motor skill (roller ball task) as a function of the manipulation of a control parameter (initial ball speed). The focus was on the relation between the rates of change in performance over practice time and the changing time scales of the evolving attractor dynamic. Results showed 3 different learning patterns to the changes in the dynamics as a function of practice that were mediated by the initial ball speed. Only participants who learned the task showed a bifurcation in coordination mode that was preceded by enhanced performance variability. The observed multiple time scales to motor learning are interpreted as the products of the dynamical stability and instability realized from (a) the continually evolving landscape dynamics due to bifurcations between attractor organization and (b) the transient phenomena associated with moving toward and away from fixed-point dynamics.

Examining creative performance over time using hierarchical linear modeling: An illustration using film directors

Longitudinal performance of 73 film directors are examined using hierarchical linear modeling (HLM). The HLM analyses model intraindividual performance trajectories (i.e., performance change over time) and interindividual differences in the trajectory parameters (i.e., initial status and rate of change in performance). Results reveal that as a group, directors' performance over careers, measured by critics' ratings, can be described using a quadratic trajectory with an increase in ratings following the initial film, followed by an eventual decline in ratings in later films. However, at the intraindividual level, directors differ in their initial status as well as rate of linear change, and some directors follow an accelerating or decelerating performance pattern. These interindividual differences in initial status, direction of change, and rate of change are related to the mean number of films per year directed by the individual. Implications and future research challenges for modeling longitudinal creative performance with HLM are discussed.

Future Packaging Directions in the 1990's and their Materials Challenges

AbstractIn the 1990's, silicon integrated circuit technology will continue to rapidly advance from VLSI towards ULSI. For example, 64 × 106 circuit microprocessor chips, 106 gate CMOS logic chips, and 105 circuit bipolar logic chips, and beyond, will make up the electronics systems of the 1990's. To support these silicon technology advances in density, performance, and cost reduction, packaging technology will also have to advance rapidly to meet packaged electronics systems requirements. Packaging solutions will be required for machines ranging from supercomputers and mainframes to minis and workstations, and for consumer electronics. Silicon technology advances will continue to enable the unique rates of change in performance, function, and cost per function that characterize the information technology industry, including the computer, communications, and consumer electronics industries.

Dichotic and monotic masking of CV's by CV second formants with different transition starting values.

Listeners were asked to identify ambiguous and unambiguous stop-vowel targets placed in monotic and dichotic competition with second formants (bleats) from voiced consonant-vowel (CV) syllables lying along a place-of-articulation continuum. Target performance varied with bleat-continuum position as well as bleat intensities. In cases where target errors occurred, either dichotically or monotically, they reflected predominantly the place cue of the bleat. This result, like that of previous studies, suggests the dominance of target or bleat reflects the relative "salience" of the two signals' cues. Differences were seen between monotic and dichotic conditions in the rate of change in performance with bleat intensity and continuum position. The rate of monotic performance change was a more precipitous (higher slope) function of these variables than was dichotic performance. This difference was interpreted as suggesting that monotic interference includes a peripheral masking component which is sensitive to the relative spectral energies of target and bleat. Dichotic effects, in contrast, seem to primarily reflect the operation of (central) processes which grant different perceptual weights to signals' cues depending on their intensity-dependent saliences. The observation that ambiguity, per se, of the targets (or the CV's from which the bleats were extracted) played little role in predicting results, was interpreted as reflecting a primarily prephonetic (i.e., auditory) locus for both monotic and dichotic interactions.

Estimation of genetic change in farm livestock using field records

This paper describes the estimation of genetic changes in farm livestock using field data. The method proposed depends on a difference in rate of change in performance of the population and of the successive progenies of individual sires. The change in the population with time is taken as t+g, where t represents environmental change and g represents genetic change, while the within-sire change is taken as t+½g. Their difference measures half the genetic change.This principle can be applied, with certain precautions, tofielddata where there is some spread of sires over time. The method has two advantages over other methods in that past as well as current changes can be measured and no additional facilities are required. However, selection among sires may bias the estimates of genetic change. Approximate sampling errors of the estimates of change can be obtained and hence the rate of genetic change which a certain body of data will demonstrate to be significant can be estimated.The method was applied to a set of pig records collected over nine years by a private pig breeder. There was considerable change with time in all six traits examined and in at least three of them there appeared to have been a substantial genetic change accounting for the whole of the observed change.