Investigating the effects of physical and cognitive demands on quality of performance and subjective responses under pacing/ takt time

Assembly work requires high levels of performance and quality but may involve complex cognitive and physical tasks. There is evidence that physical and cognitive workloads are not separate, but may interact. Work in exercise and simple physical tasks suggests that physical load may lead to changes in cognitive performance, and in perceived workload. The aim of this thesis is to examine physical and cognitive interactions that might affect assembly work. First, observation was undertaken in industry to identify the physical and cognitive factors relevant to examples of assembly lines. From this, a task analysis of a simulated assembly task was developed. Three experimental studies were conducted, based upon the simulated assembly task, in order to investigate three main assembly variables; working height, memory load and pacing. The first study showed that the number of completed assemblies was reduced when performed at higher pacing and while working at above shoulder height. The number of components dropped was higher when performed at above shoulder height. When the task was performed at elbow height ‘wait’ time increased as the beep time was found to be higher at elbow height than the above shoulder height, which led to increase wait time when performing the task at elbow height. Subjective measures (NASA TLX) showed that temporal demand and effort were reported as higher during high pacing. Perceived physical and temporal demand increased when working above shoulder height. An interaction on subjective measure was identified between pacing and working height. Performance of NASA TLX was found to be poor when performing the assembly operation at high pacing/Takt and above shoulder height as compared to working at high pacing/ Takt and elbow height. In the second study the experimental design was modified by changing the assembly order to variable assembly and consistent assembly, which represented single model assembly line (where only one type of assembly is being processed) and mixed model assembly line (different types of products being processed). Study 2 was found to be more mentally demanding due to task complexity. However, it was also found that completed assemblies were higher for the consistent assembly task. Subjective measures reported stress as being higher for higher pacing and variable assembly. The final study combined the variables from the first two studies as well as investigating different levels of memory load. Performance times for variable assembly were longer and resulted in less correct code responses. A higher memory load resulted in a higher performance time and lower correct code responses as well as fewer completed assemblies. An interaction between working height and perceived mental workload was found. Results showed that perceived temporal demand and perceived effort of NASA TLX were found to be higher when performing the assembly operation at elbow height and high memory as compared to the assembly operation performed at elbow height and low memory. It was also found that memory load affects perceived physical demand. For industry the findings suggest that in variable (mixed model) assembly different levels of pacing, working height and cognitive demands may affect workers’ performance both physically and mentally. Demands will be higher when working at variable assembly but also performance will vary where variable and consistent assembly are used together. The research also discusses theories that might be most useful for describing these effects

Investigating the effects of physical and cognitive demands on quality of performance and subjective responses under pacing/ takt time

Assembly work requires high levels of performance and quality but may involve complex cognitive and physical tasks. There is evidence that physical and cognitive workloads are not separate, but may interact. Work in exercise and simple physical tasks suggests that physical load may lead to changes in cognitive performance, and in perceived workload. The aim of this thesis is to examine physical and cognitive interactions that might affect assembly work. First, observation was undertaken in industry to identify the physical and cognitive factors relevant to examples of assembly lines. From this, a task analysis of a simulated assembly task was developed. Three experimental studies were conducted, based upon the simulated assembly task, in order to investigate three main assembly variables; working height, memory load and pacing. The first study showed that the number of completed assemblies was reduced when performed at higher pacing and while working at above shoulder height. The number of components dropped was higher when performed at above shoulder height. When the task was performed at elbow height ‘wait’ time increased as the beep time was found to be higher at elbow height than the above shoulder height, which led to increase wait time when performing the task at elbow height. Subjective measures (NASA TLX) showed that temporal demand and effort were reported as higher during high pacing. Perceived physical and temporal demand increased when working above shoulder height. An interaction on subjective measure was identified between pacing and working height. Performance of NASA TLX was found to be poor when performing the assembly operation at high pacing/Takt and above shoulder height as compared to working at high pacing/ Takt and elbow height. In the second study the experimental design was modified by changing the assembly order to variable assembly and consistent assembly, which represented single model assembly line (where only one type of assembly is being processed) and mixed model assembly line (different types of products being processed). Study 2 was found to be more mentally demanding due to task complexity. However, it was also found that completed assemblies were higher for the consistent assembly task. Subjective measures reported stress as being higher for higher pacing and variable assembly. The final study combined the variables from the first two studies as well as investigating different levels of memory load. Performance times for variable assembly were longer and resulted in less correct code responses. A higher memory load resulted in a higher performance time and lower correct code responses as well as fewer completed assemblies. An interaction between working height and perceived mental workload was found. Results showed that perceived temporal demand and perceived effort of NASA TLX were found to be higher when performing the assembly operation at elbow height and high memory as compared to the assembly operation performed at elbow height and low memory. It was also found that memory load affects perceived physical demand. For industry the findings suggest that in variable (mixed model) assembly different levels of pacing, working height and cognitive demands may affect workers’ performance both physically and mentally. Demands will be higher when working at variable assembly but also performance will vary where variable and consistent assembly are used together. The research also discusses theories that might be most useful for describing these effects

Parachute mitral valve with late presentation: rare case reports

Congenital mitral stenosis involves the annulus, the zone immediately above and contiguous with the annulus, the leaflets, the chordae tendineae, and the papillary muscles. In a parachute mitral valve (PMV), all chordae tendineae which are usually shorter and thicker than normal type, inserted into this single papillary muscle. This condition restricts the motion of leaflets and obstructs the blood flow into the left ventricle during diastole. Here we present two cases of severe congenital mitral stenosis with severe pulmonary hypertension due to parachute mitral valve that allowed survival into adulthood without any specific treatment

Global burden of cardiovascular diseases and risk factors, 1990–2019: update from the GBD 2019 study

Cardiovascular diseases (CVDs), principally ischemic heart disease (IHD) and stroke, are the leading cause of global mortality and a major contributor to disability. This paper reviews the magnitude of total CVD burden, including 13 underlying causes of cardiovascular death and 9 related risk factors, using estimates from the Global Burden of Disease (GBD) Study 2019. GBD, an ongoing multinational collaboration to provide comparable and consistent estimates of population health over time, used all available population-level data sources on incidence, prevalence, case fatality, mortality, and health risks to produce estimates for 204 countries and territories from 1990 to 2019. Prevalent cases of total CVD nearly doubled from 271 million (95% uncertainty interval [UI]: 257 to 285 million) in 1990 to 523 million (95% UI: 497 to 550 million) in 2019, and the number of CVD deaths steadily increased from 12.1 million (95% UI:11.4 to 12.6 million) in 1990, reaching 18.6 million (95% UI: 17.1 to 19.7 million) in 2019. The global trends for disability-adjusted life years (DALYs) and years of life lost also increased significantly, and years lived with disability doubled from 17.7 million (95% UI: 12.9 to 22.5 million) to 34.4 million (95% UI:24.9 to 43.6 million) over that period. The total number of DALYs due to IHD has risen steadily since 1990, reaching 182 million (95% UI: 170 to 194 million) DALYs, 9.14 million (95% UI: 8.40 to 9.74 million) deaths in the year 2019, and 197 million (95% UI: 178 to 220 million) prevalent cases of IHD in 2019. The total number of DALYs due to stroke has risen steadily since 1990, reaching 143 million (95% UI: 133 to 153 million) DALYs, 6.55 million (95% UI: 6.00 to 7.02 million) deaths in the year 2019, and 101 million (95% UI: 93.2 to 111 million) prevalent cases of stroke in 2019. Cardiovascular diseases remain the leading cause of disease burden in the world. CVD burden continues its decades-long rise for almost all countries outside high-income countries, and alarmingly, the age-standardized rate of CVD has begun to rise in some locations where it was previously declining in high-income countries. There is an urgent need to focus on implementing existing cost-effective policies and interventions if the world is to meet the targets for Sustainable Development Goal 3 and achieve a 30% reduction in premature mortality due to noncommunicable diseases

Global Burden of Cardiovascular Diseases and Risk Factors, 1990–2019: Update From the GBD 2019 Study

Cardiovascular diseases (CVDs), principally ischemic heart disease (IHD) and stroke, are the leading cause of global mortality and a major contributor to disability. This paper reviews the magnitude of total CVD burden, including 13 underlying causes of cardiovascular death and 9 related risk factors, using estimates from the Global Burden of Disease (GBD) Study 2019. GBD, an ongoing multinational collaboration to provide comparable and consistent estimates of population health over time, used all available population-level data sources on incidence, prevalence, case fatality, mortality, and health risks to produce estimates for 204 countries and territories from 1990 to 2019. Prevalent cases of total CVD nearly doubled from 271 million (95% uncertainty interval [UI]: 257 to 285 million) in 1990 to 523 million (95% UI: 497 to 550 million) in 2019, and the number of CVD deaths steadily increased from 12.1 million (95% UI:11.4 to 12.6 million) in 1990, reaching 18.6 million (95% UI: 17.1 to 19.7 million) in 2019. The global trends for disability-adjusted life years (DALYs) and years of life lost also increased significantly, and years lived with disability doubled from 17.7 million (95% UI: 12.9 to 22.5 million) to 34.4 million (95% UI:24.9 to 43.6 million) over that period. The total number of DALYs due to IHD has risen steadily since 1990, reaching 182 million (95% UI: 170 to 194 million) DALYs, 9.14 million (95% UI: 8.40 to 9.74 million) deaths in the year 2019, and 197 million (95% UI: 178 to 220 million) prevalent cases of IHD in 2019. The total number of DALYs due to stroke has risen steadily since 1990, reaching 143 million (95% UI: 133 to 153 million) DALYs, 6.55 million (95% UI: 6.00 to 7.02 million) deaths in the year 2019, and 101 million (95% UI: 93.2 to 111 million) prevalent cases of stroke in 2019. Cardiovascular diseases remain the leading cause of disease burden in the world. CVD burden continues its decades-long rise for almost all countries outside high-income countries, and alarmingly, the age-standardized rate of CVD has begun to rise in some locations where it was previously declining in high-income countries. There is an urgent need to focus on implementing existing cost-effective policies and interventions if the world is to meet the targets for Sustainable Development Goal 3 and achieve a 30% reduction in premature mortality due to noncommunicable diseases

Global age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021

Background Estimates of demographic metrics are crucial to assess levels and trends of population health outcomes. The profound impact of the COVID-19 pandemic on populations worldwide has underscored the need for timely estimates to understand this unprecedented event within the context of long-term population health trends. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 provides new demographic estimates for 204 countries and territories and 811 additional subnational locations from 1950 to 2021, with a particular emphasis on changes in mortality and life expectancy that occurred during the 2020–21 COVID-19 pandemic period. Methods 22 223 data sources from vital registration, sample registration, surveys, censuses, and other sources were used to estimate mortality, with a subset of these sources used exclusively to estimate excess mortality due to the COVID-19 pandemic. 2026 data sources were used for population estimation. Additional sources were used to estimate migration; the effects of the HIV epidemic; and demographic discontinuities due to conflicts, famines, natural disasters, and pandemics, which are used as inputs for estimating mortality and population. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate under-5 mortality rates, which synthesised 30 763 location-years of vital registration and sample registration data, 1365 surveys and censuses, and 80 other sources. ST-GPR was also used to estimate adult mortality (between ages 15 and 59 years) based on information from 31 642 location-years of vital registration and sample registration data, 355 surveys and censuses, and 24 other sources. Estimates of child and adult mortality rates were then used to generate life tables with a relational model life table system. For countries with large HIV epidemics, life tables were adjusted using independent estimates of HIV-specific mortality generated via an epidemiological analysis of HIV prevalence surveys, antenatal clinic serosurveillance, and other data sources. Excess mortality due to the COVID-19 pandemic in 2020 and 2021 was determined by subtracting observed all-cause mortality (adjusted for late registration and mortality anomalies) from the mortality expected in the absence of the pandemic. Expected mortality was calculated based on historical trends using an ensemble of models. In location-years where all-cause mortality data were unavailable, we estimated excess mortality rates using a regression model with covariates pertaining to the pandemic. Population size was computed using a Bayesian hierarchical cohort component model. Life expectancy was calculated using age-specific mortality rates and standard demographic methods. Uncertainty intervals (UIs) were calculated for every metric using the 25th and 975th ordered values from a 1000-draw posterior distribution. Findings Global all-cause mortality followed two distinct patterns over the study period: age-standardised mortality rates declined between 1950 and 2019 (a 62·8% [95% UI 60·5–65·1] decline), and increased during the COVID-19 pandemic period (2020–21; 5·1% [0·9–9·6] increase). In contrast with the overall reverse in mortality trends during the pandemic period, child mortality continued to decline, with 4·66 million (3·98–5·50) global deaths in children younger than 5 years in 2021 compared with 5·21 million (4·50–6·01) in 2019. An estimated 131 million (126–137) people died globally from all causes in 2020 and 2021 combined, of which 15·9 million (14·7–17·2) were due to the COVID-19 pandemic (measured by excess mortality, which includes deaths directly due to SARS-CoV-2 infection and those indirectly due to other social, economic, or behavioural changes associated with the pandemic). Excess mortality rates exceeded 150 deaths per 100 000 population during at least one year of the pandemic in 80 countries and territories, whereas 20 nations had a negative excess mortality rate in 2020 or 2021, indicating that all-cause mortality in these countries was lower during the pandemic than expected based on historical trends. Between 1950 and 2021, global life expectancy at birth increased by 22·7 years (20·8–24·8), from 49·0 years (46·7–51·3) to 71·7 years (70·9–72·5). Global life expectancy at birth declined by 1·6 years (1·0–2·2) between 2019 and 2021, reversing historical trends. An increase in life expectancy was only observed in 32 (15·7%) of 204 countries and territories between 2019 and 2021. The global population reached 7·89 billion (7·67–8·13) people in 2021, by which time 56 of 204 countries and territories had peaked and subsequently populations have declined. The largest proportion of population growth between 2020 and 2021 was in sub-Saharan Africa (39·5% [28·4–52·7]) and south Asia (26·3% [9·0–44·7]). From 2000 to 2021, the ratio of the population aged 65 years and older to the population aged younger than 15 years increased in 188 (92·2%) of 204 nations. Interpretation Global adult mortality rates markedly increased during the COVID-19 pandemic in 2020 and 2021, reversing past decreasing trends, while child mortality rates continued to decline, albeit more slowly than in earlier years. Although COVID-19 had a substantial impact on many demographic indicators during the first 2 years of the pandemic, overall global health progress over the 72 years evaluated has been profound, with considerable improvements in mortality and life expectancy. Additionally, we observed a deceleration of global population growth since 2017, despite steady or increasing growth in lower-income countries, combined with a continued global shift of population age structures towards older ages. These demographic changes will likely present future challenges to health systems, economies, and societies. The comprehensive demographic estimates reported here will enable researchers, policy makers, health practitioners, and other key stakeholders to better understand and address the profound changes that have occurred in the global health landscape following the first 2 years of the COVID-19 pandemic, and longer-term trends beyond the pandemic