Rate Of Decline In Performance Research Articles

Impact of the Russia–Ukraine Conflict on Global Marine Network Based on Massive Vessel Trajectories

Maritime transportation plays a vital role in global trade, and studying the resilience of the global maritime network is crucial for ensuring its sustainable development. Currently, the ongoing conflict between Russia and Ukraine has garnered significant global attention. However, there is a lack of specific research on the impact of the conflict on maritime shipping, particularly the resilience of the global maritime network. This paper proposes a resilience assessment framework under the influence of significant events by combining complex network metrics and network performance indicators from the resilience triangle model. It quantitatively evaluates the resilience changes in the global maritime network before and after the outbreak of the Russia–Ukraine conflict. The experiment utilizes real automatic identification system (AIS) maritime trajectory data to quantify and visualize the changes in global maritime traffic during a 20-day period before and after the conflict, constructing the global maritime network for resilience calculations. The research findings indicate the following changes occurred after the Russia–Ukraine conflict. Firstly, the global maritime industry experienced overall growth, with increased ship transportation between ports. Transportation in certain regions was negatively affected, with a significant decrease in ship activities in the Black Sea and Adriatic Sea areas. The positions of Russia and Ukraine in the world maritime industry noticeably declined. Secondly, the network connectivity, network size, and network density of the global maritime network significantly increased, indicating an enhanced network resilience. According to our quantitative results, from a topological perspective, we observed the following changes: network connectivity increased by 27.2%, network scale increased by 36.6%, network density increased by 32.4%, and network resilience increased by 18.6%. Thirdly, the global maritime network is characterized by a high degree of heterogeneity, and the impact of conflicts on the heterogeneity of the shipping network is not significant. Finally, the network exhibited a slower performance decline under random attacks, while deliberate attacks led to a sharp decline. Due to the adaptive nature of the maritime network, the resilience of the network improves in terms of its topology following the outbreak of conflicts. After conflict incidents, the rate of performance decline during simulated attacks is lower compared to the pre-conflict period.

Age-related declines in muscle and respiratory function are proportionate to declines in performance in Master Track Cyclists

PurposeRespiratory and musculoskeletal function decline with age, irrespective of physical activity levels. Previous work has suggested that the age-related rate of decline in function of these two systems might be similar, but it is not known to what extent each system contributes to decreasing performance in ageing master cyclists. Therefore, the purposes of this study are (1) whether the age-related rate of decline in respiratory function, respiratory muscle strength, muscle architecture, muscle function, haemoglobin concentration, haematocrit and performance in master cyclists is uniform and (2) which parameters contribute most to the reduction in performance with age.MethodsMaster cyclists were recruited during the Track Cycling Masters World Championship 2019 in Manchester. Respiratory function and respiratory muscle strength were determined using spirometry and a mouth pressure device, respectively. Muscle architecture was determined using ultrasonography, and muscle function by countermovement jump.ResultsForced expiratory volume in the first second, forced vital capacity, fascicle length, muscle thickness, take-off velocity, jump power, jump power per body mass, handgrip strength, haemoglobin concentration and performance correlated negatively with age (p ≤ 0.043). The age-related rate of decline did not differ significantly between parameters (p = 0.124), but it was slower for haemoglobin concentration (p = 0.041). Take-off velocity was the major determinant of performance in 200, 500 and 2000 m track cycling disciplines (R2adj = 0.675, 0.786 and 0.769, respectively; p < 0.001).ConclusionAge-related decline in respiratory and muscle system is accompanied by a similar rate of decline in performance. The major contribution to the age-related decline of performance is reduced muscle function, specifically take-off velocity.

Performance Declines Are Accelerated in the Oldest-Old Track and Field Athletes 80 to 94 Years of Age.

Physical performance declines with age, even in exercising, healthy individuals without major illnesses or orthopedic issues. The rate of performance decline is often reported to accelerate after the age of 70 years, but almost no data are available on performance in the fittest oldest-old. To assess their rate of decline in performance, the biggest data set of track and field athletes aged ≥80 years (1567 results) ever published was generated for different disciplines from German Athletics Federations including 1997-2019. Performance at age 80 years of athletes still participating at age 85 years was compared with those who discontinued. Only 1 of every 22 athletes competing at age 80 years still competed at age 90 years. The performance decline was more than three times as steep in athletes aged ≥80 years (on average 1.62%/year, men: 100 m, R = 0.31, p < 0.001; 200 m, R = 0.17, p = 0.037; long jump, R = -0.37, p < 0.001; shot put, R = -0.32, p < 0.001; discus, R = -0.34, p < 0.001; javelin, R = -0.43, p < 0.001; women: shot put, R = -0.24, p = 0.017; discus, R = -0.33, p = 0.010) compared with athletes aged 30-69 years (0.46%/year) and accelerated at an average of 67 years. This accelerated decline was most pronounced in the sprint disciplines and lowest in the throws. Performance at age 80 years was similar in athletes still participating at age 85 years to those who discontinued, and the variability in results was decreased after age 90 years. In conclusion, physical performance declines more than three times as fast after around the age of 67 years compared with before. This was particularly the case for sprinting but was not a result of dropout of poorer performing athletes.

Compensatory Neural Activity in Response to Cognitive Fatigue.

Fatigue refers to changes in objective performance and subjective effort induced by continuous task performance. We examined the neural underpinnings of cognitive fatigue in humans using a prolonged continuous performance task and high-density electroencephalography with the goal of determining whether compensatory processes exist to maintain performance in the face of fatigue. We identified brain activity demonstrating an inverted U-shaped time-on-task profile. This brain activity showed features consistent with a compensatory role including: peaking between 60 and 100 min into the task, a positive association with behavioral performance only during this interval, and accelerated performance decline following its peak. These findings may be relevant to understanding individual differences in cognitive fatigue and developing interventions for clinical conditions afflicted by fatigue.

A comparison of Fuel Cell Testing protocols – A case study: Protocols used by the U.S. Department of Energy, European Union, International Electrotechnical Commission/Fuel Cell Testing and Standardization Network, and Fuel Cell Technical Team

Argonne National Laboratory (Argonne) and the Joint Research Centre-Institute for Energy and Transport (JRC-IET) collaborated to understand the aging behavior of polymer-electrolyte membrane stacks when operated under different duty cycles. The duty cycles were that used by the U.S. Department of Energy (DST) and the US Fuel Cell Council; the New European Drive Cycle (ECE R15); that used in IEC-TS62282-7-1 (IEC) and Fuel Cell Testing and Standardization Network; and the one proposed by the US Driving Research and Innovation for Vehicle Efficiency and Energy Sustainability Fuel Cell Technical Team (FCTT).The stacks were cycled using the duty profile in each protocol for 200 h; stack performance was measured every 100 h. Analysis of the relative changes in the average cell potentials at 180 A showed that the rate of performance decline could be ordered as IEC > ECE R15, the latter being slightly greater than or approximately equal to DST and FCTT. Comparing this ordering to the length of time at full power in the duty cycle with the degradation rates shows that they are related. Most likely, the underlying cause of performance decline can be attributed to the manner in which the product water interacts with the stack components.

Intraindividual Variability in Basic Reaction Time Predicts Middle-Aged and Older Pilots' Flight Simulator Performance

Intraindividual variability (IIV) is negatively associated with cognitive test performance and is positively associated with age and some neurological disorders. We aimed to extend these findings to a real-world task, flight simulator performance. We hypothesized that IIV predicts poorer initial flight performance and increased rate of decline in performance among middle-aged and older pilots. Two-hundred and thirty-six pilots (40-69 years) completed annual assessments comprising a cognitive battery and two 75-min simulated flights in a flight simulator. Basic and complex IIV composite variables were created from measures of basic reaction time and shifting and divided attention tasks. Flight simulator performance was characterized by an overall summary score and scores on communication, emergencies, approach, and traffic avoidance components. Although basic IIV did not predict rate of decline in flight performance, it had a negative association with initial performance for most flight measures. After taking into account processing speed, basic IIV explained an additional 8%-12% of the negative age effect on initial flight performance. IIV plays an important role in real-world tasks and is another aspect of cognition that underlies age-related differences in cognitive performance.

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.

Age-related Performance Declines In Men's Freestlye Swimming Events

Routine, daily exercise has been shown to decrease mortality and morbidity risk in older adults (Pateron, Jones, and Rice, 2007), however the role of continued exercise on athletic performance is less clear. Athletic performance is expected to decrease dramatically during the sixth decade of life (Tanaka and Seals, 2003), but more research is needed to determine how long athletic performance can be maintained. PURPOSE: This analysis was designed to determine the relationship between age and freestyle swim performance in men. METHODS: Data was collected from the 'Top Ten' times for 2006 and 2007, as reported on the United States Masters Swimming website (usms.org). Times from 6 freestyle events (short course yards) were collected for 13 age groups, from 25-29 years old, and in 5 year increments up to 85-89 years old. Data were analyzed using a two-way ANOVA with SPSS. RESULTS: Statistical analysis found swim times of 25 year olds up to 54 year olds in the 50 yd and 200 yd freestyle were the same. The 100 yd freestyle showed equivalent swim times for age 25 to 64. The 500, 1000 and 1650 yd freestyle events had equivalent swim times for ages 25 to 59. Swimmers older than these ranges showed increasing rates of decline in performance. The individual events showed significant differences in the age*distance interaction. Regression analysis found an increasing rate of decline as race distance increased (range of 0.0607 to 2.0064 s · yr-1). CONCLUSIONS: Swimmers are able to maintain athletic performance into their 50s, and into the 60s for the 100 yd freestyle. This data supports maintenance of athletic performance well into middle age with consistent exercise. A previous study of Masters Track Athletes found significant differences for each decade of age after 30 (Baker, Tang, and Turner, 2003). In contrast, these results show no significant differences until at least 55 years old. The age range with equivalent performances was shared by the longer distance events (500 - 1650 yd), however there was no consistent pattern for age-related changes as indicated by the significant age*distance interaction. Performance appears to be better preserved in the shorter distance events based on the regression analysis of each event.

Recurrent seizures induce a reversible impairment in a spatial hidden goal task

A major question concerning the learning and memory deficits characteristic of epilepsy is the relative importance of the initial insult that leads to recurrent, unprovoked seizures versus the seizures themselves. A related issue is whether seizure-induced cognitive decline is permanent or reversible when convulsions cease. To address these problems, adult rats were extensively trained in the "spatial accuracy task," a dry-land analog of the Morris water maze. This task allows the rat's estimate of the location of a hidden goal zone to be repeatedly measured within each behavioral session. One aim was to measure, in well-trained animals, the time course of any cognitive impairment caused by a daily flurothyl-induced generalized seizure over 11 days. A second aim was to look for possible recovery during 9 subsequent days with no seizures. We saw a cumulative degradation in spatial performance during the seizure days and reversal of the deficit after seizures were stopped such that performance returned to baseline. Interestingly, the rate of learning to an asymptote, the rate of performance decline during one-per-day seizures and the rate of relearning during the recovery period were all similar. Given that the hippocampus plays an important role in spatial memory and that it is the brain structure most vulnerable to abnormal excitation the implication is that the hippocampus remains essential for precise spatial navigation even after prolonged training in locating a fixed goal zone. Clinically, this finding questions the assumption that patients who experience seizures should return to a baseline cognitive level within hours.

Very low lead exposures and children's neurodevelopment

We remain far from achieving the goal of eliminating lead-associated neurodevelopmental morbidities in children. New evidence regarding the blood lead levels at which morbidities occur have led to calls for the Centers for Disease Control and Prevention to reduce the current screening guideline of 10 microg/dl. The review evaluates the basis for these calls. Adverse outcomes, such as reduced intelligence quotient and academic deficits, occur at levels below 10 microg/dl. Some studies suggest that the rate of decline in performance is greater at levels below 10 microg/dl than above 10 microg/dl, although a plausible mechanism has not been identified. Increased exposure is also associated with neuropsychiatric disorders such as attention deficit hyperactivity disorder and antisocial behavior. Functional imaging studies are beginning to provide insight into the neural substrate of lead's neurodevelopmental effects. Current protocols for chelation therapy appear ineffective in preventing such effects, although environmental enrichment might do so. No level of lead exposure appears to be 'safe' and even the current 'low' levels of exposure in children are associated with neurodevelopmental deficits. Primary prevention of exposure provides the best hope of mitigating the impact of this preventable disease.

Age-Related Rates of Decline in Performance among Elite Senior Athletes

Background Age-related disability and lost independence currently plague one third of older Americans. Many causes of disability, lost muscle mass and bone mineral density, are modifiable with exercise. Most exemplary of successful aging are the Senior Olympians; this group of vital athletes exhibit persistently high levels of functional capacity. Purpose This study describes demographic data, injury characteristics and the effect of aging on physical performance in senior athletes to identify key time points for intervention to address declining performance. Study Design Cross-sectional study; Level of evidence, 4. Methods Senior Olympians (>50 years) participating in the 2001 National Senior Olympic Games were surveyed for demographic and health characteristics. Age-related changes in physical performance were determined from mean winning performance times in track and field events. These were plotted against age and task for men and women. Analysis of variance and intergroup significance were analyzed using the Tukey procedure. Percentage performance change across events was compared. The 2001 National Senior Olympic Games results were compared with American track and field record holders. Results Senior athletes’ performance declined (male and female) approximately 3.4% per year over 35 years of competition—slowly from age 50 to 75 years and dramatically after age 75 years. Men showed no difference in decline of sprint and endurance events, whereas the decline in the sprint was greater than in endurance for women, especially after the age of 75 years. Conclusion Even the healthiest examples of musculoskeletal aging experience significant performance declines around age 75 years. This may be a key time point for preventive intervention.

Current pharmacologic options for patients with Alzheimer's disease

BackgroundThe aim of the current study was to provide general practitioners with an overview of the available treatment options for Alzheimer's disease (AD). Since general practitioners provide the majority of medical care for AD patients, they should be well versed in treatment options that can improve function and slow the progression of symptoms.DesignBiomedical literature related to acetylcholinesterase inhibitors (AChEIs) was surveyed. In the United States, there are four AChEIs approved for the treatment of AD: tacrine, donepezil, rivastigmine, and galantamine. There are other agents under investigation, but at present, AChEIs are the only approved drug category for AD treatment.Measurements and Main ResultsAD is becoming a major public health concern and underdiagnosis is a significant problem (with only about half of AD patients being diagnosed and only half of those diagnosed actually being treated). Clinical trials have demonstrated that patients with AD who do not receive active treatment decline at more rapid rates than those who do.ConclusionsGiven that untreated AD patients show decline in three major areas (cognition, behavior, and functional ability), if drug treatment is able to improve performance, maintain baseline performance over the long term, or allow for a slower rate of decline in performance, each of these outcomes should be viewed a treatment success.

Rate of memory decline in AD is related to education and occupation: cognitive reserve?

To determine whether the rate of decline in performance on a memory test is more rapid in AD patients with higher versus lower educational and occupational attainment. Epidemiologic and imaging studies have suggested that, given comparable clinical severity of dementia, AD pathology is more advanced in patients with higher educational and occupational attainment. Because educational and occupational attainment should not influence the progression of AD pathology, and because severe AD pathology will eventually produce a mortality-causing condition, people with higher attainment might experience clinical AD for a shorter time and have a more rapid clinical progression. A total of 177 AD patients were tested yearly for up to four study visits with the Selective Reminding Test (a memory test). Analysis of prospective change in the total recall score was performed by applying generalized estimating equations to regression analyses with repeated measures. At the initial visit, scores were comparable in the high- and low-education and the high- and low-occupation groups. Overall, memory scores declined by approximately 1 point yearly (p<0.01). There was a more rapid decline in memory scores in patients with higher educational (p<0.057) and higher occupational attainment (p<0.02). The authors then stratified patients based on their initial memory scores. The more rapid decline in memory scores associated with higher educational and occupational attainment was noted only in the group with low initial scores (p<0.05 for both). The full group and stratified group analyses were also repeated controlling for other potentially relevant variables including age, gender, race, ethnicity, and the presence of extrapyramidal signs, stroke, or at least one apolipoprotein E-epsilon4 allele. The results remained unchanged. Memory declined more rapidly in AD patients with higher educational and occupational attainment. This adds support to the idea that the discontinuity between the degree of AD pathology and the observed clinical severity of AD is mediated through some form of reserve.

Relationship of Neurological Function and Age in Older Women

The decline of neurological and neuromuscular function with age in older women and in subgroups of older women with selected risk factors for poor function is described using cross- sectional analyses of data on 8,080 women from the multicenter Study of Osteoporotic Fractures. All twelve performance-based tests of muscle strength, balance, gait, somatosensory discrimination and reaction time declined with increasing age. On a percentage scale, vibration threshold declined the most rapidly with age. Participants who were smokers, physically inactive, nonconsumers of alcohol, diabetics and more frequent fallers had poorer age-adjusted performance than those without these attributes. However, with a few exceptions, the rate of decline in performance with age for those with and without these characteristics did not differ significantly.

Differential effects of luminance and contrast on acuity thresholds across the visual field

Purpose: To investigate the effects of contrast and luminance on acuity thresholds across the visual field. This may shed some light on the important question of why some visual thresholds change only slowly as a function of eccentricity, whereas others fall off extremely quickly.Methods: Resolution thresholds for Gabor patches were measured in the nasal visual field using a modified yes/no staircase procedure. The effect of contrast was examined by changing the physical contrast of the Gabor stimuli between the values of 3.125 and 100%. The effect of luminance was investigated using high contrast Gabor stimuli but varying luminance over 2.7 log units with the use of neutral density filters. Natural pupils were used throughout.Results: The variation in resolution thresholds as a function of eccentricity was well described by the equation T = T0/[+(E/E2)], where T represents threshold, T0 threshold at the fovea, E is eccentricity and E2 is a parameter which describes the rate of decline in performance, representing the eccentricity at which the foveal resolution threshold halves. Changes in contrast resulted in the same logarithmic change in resolution threshold at all eccentricities, leaving the E2 value unchanged. Thresholds were proportional to the logarithm of contrast, and transforming the data in this way accounted for 98% of the variance in the eccentricity and contrast dependent data. Variations in luminance produced quite different effects, with E2 becoming significantly greater as luminance was reduced. At all eccentricities, resolution thresholds were proportional to the logarithm of retinal illuminance, but the gradient of this relationship changed markedly as a function of eccentricity, becoming close to zero at the higher eccentricities studied.Conclusions: The differential effects of contrast and luminance on acuity thresholds can be understood in terms of a pyramidal model of early vision in which reductions in suprathreshold contrast affect the signal by the same amount in all early visual filters, whereas reductions in luminance have a selective effect on smaller visual filters which are more susceptible to quantal noise.

Body-mass dependence of age-related deterioration in human muscular function

Maximal anaerobic power of human muscles declines with increasing chronological age and is correlated with body mass. This study investigated whether the rate of deterioration in human muscular function among trained weight lifters is also correlated with body mass. Cross-sectional analysis of performance data of over 1,100 Masters competitors in Olympic-style weight lifting was carried out; eight body-weight classes and six age groups were represented. Two-lift total data (sum of snatch and clean and jerk lifts) were analyzed. Mean deterioration rates in the performance of athletes of widely diverse body masses were compared over the following age ranges: 42-57, 42-62, and 42-67 yr. No statistically significant correlation (P < 0.05) was found between rate of performance decline and body mass. The relationship between body mass and the magnitude of age-related variation of deterioration rate was also studied; no significant correlation was found. Previous studies have demonstrated that performance in Olympic-style weight lifting is correlated with maximal anaerobic muscular power. This leads us to suggest that the age-related deterioration rate of anaerobic power in trained subjects may not be correlated with the body mass of the individual.

Influence of age and physical training on measures of cardiorespiratory and muscle endurance.

This study describes associations between age, physical training and measures of muscle and cardiorespiratory endurance. The subjects were 5079 healthy male soldiers aged 18-53 years from 14 Army installations in the United States. The subjects completed as many push-ups as possible in 2 min, as many sit-ups as possible in 2 min, and performed a timed 3.2-km run. The training level was assessed by asking the subjects two questions about the frequency (times each week) and duration (hours each week) of their physical training. For all three performance events there were significant declines with age, but at a given age, groups that trained more demonstrated higher performance levels than groups that trained less. For the 3.2-km run, the age-associated rate of performance decline was less in the groups that trained more, and greater amounts of training resulted in progressively less performance decline with age. For push-ups and sit-ups, the training level did not systematically influence the age-related rate of performance decline. The results suggest that tasks involving different physiological systems may be influenced differentially by age and training. Training may slow age-associated performance declines in tasks requiring cardiorespiratory endurance but not in tasks requiring muscle endurance.

Comparison of the effects of single and combined neurotoxic lesions of the nucleus basalis magnocellularis and dorsal noradrenergic bundle on learning and memory in the rat

Groups of rats received bilateral destruction of either the nucleus basalis magnocellularis (NBM) by infusion of ibotenic acid, the dorsal noradrenergic bundle (DNB) by infusion of 6-hydroxydopamine, or both NBM + DNB (COMB). These lesion groups along with sham operated controls were trained on a food reinforced spatial delayed conditional discrimination task in a T-maze. All four groups were able to attain a criterion of 85% correct responses despite significant group differences in the number of trials to criterion and number of correct responses during training. Performance of the DNB and NBM groups on acquisition trials was significantly lower than controls, significantly higher than the COMB group, but not significantly different from each other. When tested at delays of 30–300 s, all groups demonstrated parallel rates of decline in performance. On reversal learning trials, the NBM and COMB groups were significantly impaired, whereas the performance of the DNB group was better than controls. No significant interaction between the DNB and NBM lesions was observed on any of the behavioral measures. Biochemical analyses demonstrated significant reductions of choline acetyltransferase (ChAT) activity in cortex but not hippocampus of the NBM and COMB groups, and a significant reduction of norepinephrine (NE) in cortex and hippocampus of the DNB and COMB but not the NBM group. The concentration of other monoamine and amino acid neurotransmitters in the lesion groups were unchanged from controls. These results suggest that DNB and NBM lesions produce separate and independent cognitive impairments that do not severely disrupt retention of trial independent (reference memory) and trial dependent (working memory) information on this T-maze task.

The influence of eccentricity on position and movement acuities as revealed by spatial scaling

The rate of decline with increasing eccentricity of several position and movement acuities was measured using a method of spatial scaling. In this method all stimuli at each visual field location are simply magnified versions of each other. The influence of separation and eccentricity were dissociated by presenting stimuli on an iso-eccentric arc. For each task, the rate of decline in performance was quantified by the parameter E 2 which represents the eccentricity at which stimulus size must double in order to maintain performance equivalent to that at the fovea. All tasks were found to obey the concept of spatial scaling in that performance at a given field location could be equated with performance at any other location simply by a change of scale. However, the rate at which performance deteriorated with eccentricity varied over an enormous range (over 100-fold) depending on the task itself. The advantage of such diverse peripheral gradients is clear; the goal is to establish the physiological mechanisms which underlie this phenomenon.

Sentence comprehension and memory for embedded structure

An experimental simulation technique is introduced to study memory constraints affecting comprehension of embedded sentences. Memory for embedded structure is measured in a pairing task that simulates requirements imposed by sentence comprehension. With increasing memory load (number of embeddings), the rate of performance decline is consistent across all (recall and comprehension) conditions, and reflects a loss of order (as opposed to item) information. Short-term memory overload, rather than linguistic complexity, appears sufficient to account for comprehension difficulty. Performance was imperfect even with singly embedded constructions. Recall showed no abrupt failure with multiple embeddings, indicating that memory constraints are not as discontinuous as English syntax might suggest.