Shift Duration Research Articles

A discrete event simulation method for performance analysis of an additive manufacturing in the dental clinic.

Three-dimensional printing (3DP) is an evolutionary solution for making customize items for all sectors, but it has become more prominent in the healthcare sector. In this field, some solutions have to be adapted to patients. This is especially true for dentistry, where all the patients have their own unique mouth and tooth structure. It is now possible to provide an accurate model of the patient's mouth and teeth with solutions that are perfectly compatible with them, leading to the provision of a dental service with a high success rate. Even if there is a problem, it is enough to change the three-dimensional design. Therefore, it is a time-saving method, too. The purpose of this study is to investigate the role of 3DP in dentistry and to identify the processes and procedures resulting from the use of this technology. To do so, with the help of a case study, a 3DP-based dental clinic that provides implant, orthodontics, restoration and dentures services is simulated in Arena software. The current state of the system is assessed by defining appropriate evaluation criteria including net profit, utilization, waiting time, patients makespan and laboratory makespan. The simulation model is then developed with innovations such as adding an inventory control policy, creating rest time for resources and controlling the policy of sending products from laboratory to the clinic. After an extensive sensitivity analysis, improving the performance of the system is on the agenda of this paper by examining various scenarios. Results show that scenarios such as reducing some resources of the system or considering rest time in exchange for increasing the duration of the work shift can have a significant impact on clinic performance.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00170-021-08135-7.

The impact of trainees' working hour regulations on outcome in CABG and valve surgery in the State of New York.

In 2011, the Accreditation Council for Graduate Medical Education (ACGME) restricted the first-year residents' duty-hour to less than 16-hourshifts, decreased the maximum shift duration for senior residents, and increased minimum time off after on-call duties. Whether these changes may have impacted the outcomes in cardiac surgery remains unclear. We performed a difference-in-difference analysis of the New York State Cardiac Surgery Reporting System data in 2004-2006 (before the duty-hour policies change) and 2014-2016 (after the change). We evaluated differences in 30-day risk-adjusted mortality rates (RAMR) in coronary artery bypass grafting (CABG) and valve surgeries, stratifying data by hospital type: teaching hospitals (TH) versus nonteaching hospitals (NTH). NTH served as the control not affected by the duty-hour policies. (1) The overall surgical volume for CABG surgery has decreased over time (37,645-24,991), while the volume for valve surgery remained similar (20,969-21,532); (2) TH had better short-term outcomes for CABG procedures during 2014-2016 (median RAMR: 1.01% vs. 1.55% in TH vs. NTH, respectively; p = .025) as well as for valve procedures during both 2004-2006 (5.16% vs. 7.49%, p = .020) and 2014-2016 (2.59% vs. 4.09%, p = .033); (3) at difference-in-difference analysis, trainees' duty-hour regulations were not associated with worsening short-term outcomes in both CABG (p = .296) and valve (p = .651) procedures performed in TH. The introduction of the 2011 trainees' duty-hour regulations was not associated with worse short-term outcomes for CABG and valve surgery performed in the State of NY by TH.

Memantine Improves Recovery After Spreading Depolarization in Brain Slices and can be Considered for Future Clinical Trials.

Spreading depolarization (SD) has been identified as a key mediator of secondary lesion progression after acute brain injuries, and clinical studies are beginning to pharmacologically target SDs. Although initial work has focused on the N-Methyl-D-aspartate receptor antagonist ketamine, there is also interest in alternatives that may be better tolerated. We recently showed that ketamine can inhibit mechanisms linked to deleterious consequences of SD in brain slices. The present study tested the hypothesis that memantine improves recovery of brain slices after SD and explored the effects of memantine in a clinical case targeting SD. For mechanistic studies, electrophysiological and optical recordings were made from hippocampal area CA1 in acutely prepared brain slices from mice. SDs were initiated by localized microinjection of K+ in conditions of either normal or reduced metabolic substrate availability. Memantine effects were assessed from intrinsic optical signals and extracellular potential recordings. For the clinical report, a subdural strip electrode was used for continuous electrocorticographic recording after the surgical evacuation of a chronic subdural hematoma. In brain slice studies, memantine (10-300µM) did not prevent the initiation of SD, but impaired SD propagation rate and recovery from SD. Memantine reduced direct current (DC) shift duration and improved recovery of synaptic potentials after SD. In brain slices with reduced metabolic substrate availability, memantine reduced the evidence of structural disruption after the passage of SD. In our clinical case, memantine did not noticeably immediately suppress SD; however, it was associated with a significant reduction of SD duration and a reduction in the electrocorticographic (ECoG) suppression that occurs after SD. SD was completely suppressed, with improvement in neurological examination with the addition of a brief course of ketamine. These data extend recent work showing that N-Methyl-D-aspartate receptor antagonists can improve recovery from SD. These results suggest that memantine could be considered for future clinical trials targeting SD, and in some cases as an adjunct or alternative to ketamine.

19 A Comparative Analysis on Fertility Success Among Physician Specialties

Physicians are exposed to a variety of psychological and physical occupational hazards. Emergency Physicians serve as the initial contact for the most critically ill and injured. Adding to these stressors are 24-hour staffing demands of the emergency department (ED) with varying shift times and durations. This increases not only the physical demands but also the psychological stressors. Prior research has recognized both physical and psychological stressors on women’s fertility. Physician specialties traditionally have differing time pressures, compassion fatigue, and occupational culture that may also affect fertility.

Personality Traits and Insomnia Symptoms in Shift Workers.

The discrepancy between natural sleep-wake rhythm and actual sleep times in shift workers can cause sleep loss and negative daytime consequences. Irregular shift schedules do not follow a fixed structure and change frequently, which makes them particularly harmful and makes affected individuals more susceptible to insomnia. The present study compares insomnia symptoms of non-shift workers, regular shift workers, and irregular shift workers and takes into account the moderating role of the Big Five personality traits and levels of perfectionism. Employees of an Austrian railway company completed an online survey assessing shift schedules, sleep quality and duration, daytime sleepiness, and personality traits. A total of 305 participants, of whom 111 were non-shift workers, 60 regular shift workers, and 134 irregular shift workers, made up the final sample. Irregular shift workers achieved significantly worse scores than one or both of the other groups in time in bed, total sleep time, sleep efficiency, sleep duration, sleep quality, sleep latency, and the number of awakenings. However, the values of the irregular shifts workers are still in the average range and do not indicate clinical insomnia. Participants working regular shifts reported the best sleep quality and longest sleep duration and showed the least nocturnal awakenings, possibly due to higher conscientiousness- and lower neuroticism scores in this group. Agreeableness increased the effect of work schedule on total sleep time while decreasing its effect on the amount of sleep medication taken. Perfectionism increased the effect of work schedule on time in bed and total sleep time. Generalization of results is limited due to the high percentage of males in the sample and using self-report measures only.

Simulating approaches to emergency department pandemic physician staffing during COVID-19.

During pandemics, emergency departments (EDs) are challenged by the need to replace quarantined ED staff and avoid staffing EDs with nonemergency medicine (EM) trained physicians. We sought to design and examine three feasible ED staffing models intended to safely schedule EM physicians to staff three EDs within a health system during a prolonged infectious disease outbreak. We conducted simulation analyses examining the strengths and limitations of three ED clinician staffing models: two-team and three-team fixed cohort, and three-team unfixed cohort. Each model was assessed with and without immunity, and by varying infection rates. We assumed a 12-week pandemic disaster requiring a 2-week quarantine. The outcome, time to staffing shortage, was defined as depletion of available physicians in both 8- and 12-hour shift duration scenarios. All staffing models initially showed linear physician attrition with higher infection rates resulting in faster staffing shortages. The three-team fixed cohort model without immunity was not viable beyond 11 weeks. The three-team unfixed cohort model without immunity avoided staffing shortage for the duration of the pandemic up to an infection rate of 50 percent. The two-team model without immunity also avoided staffing shortage up to 30 percent infection rate. When accounting for immunity, all models behaved similarly initially but returned to adequate staffing during week 5 of the pandemic. Simulation analyses reveal fundamental tradeoffs that are critical to designing feasible pandemic disaster staffing models. Emergency physicians should test similar models based on local assumptions and capacity to ensure adequate staffing preparedness for prolonged pandemics.

A hybrid metaheuristic for smart waste collection problems with workload concerns

In this paper, a hybrid metaheuristic is developed to solve the smart waste collection problem with workload concerns. It is composed by: (i) a look-ahead heuristic aiming at deciding the days in which collection is necessary and which bins need to be collected (must-go) considering the present bin fill levels and future bin fill level predictions; and (ii) a simulated annealing/neighborhood search algorithm to choose the bins that are profitable to collect and the best route(s) to visit the bins. This algorithm was developed to find solutions within a relatively short amount of time (we considered two hours as reference), as required for practical operations. The proposed hybrid metaheuristic is applied to randomly-generated test instances of sizes up to 500 bins and to a real case study of recyclables collection, leading to results that demonstrate its effectiveness and usefulness in practice when dealing with large-size instances. For the real case study, involving a major waste management company in Portugal, the profit achieved by the hybrid metaheuristic is at least 45% higher than the profit obtained by the company, and, at the same time, compliance with maximum shift duration and route workload balance is clearly better when the metaheuristic is used than in current operations.

Long-term night shift work is associated with the risk of atrial fibrillation and coronary heart disease.

The aim of this study was to test whether current and past night shift work was associated with incident atrial fibrillation (AF) and whether this association was modified by genetic vulnerability. Its associations with coronary heart disease (CHD), stroke, and heart failure (HF) were measured as a secondary aim. This cohort study included 283 657 participants in paid employment or self-employed without AF and 276 009 participants free of CHD, stroke, and HF at baseline in the UK Biobank. Current and lifetime night shift work information was obtained. Cox proportional hazard models were used. Weighted genetic risk score for AF was calculated. During a median follow-up of 10.4 years, 5777 incident AF cases were documented. From 'day workers', 'shift but never/rarely night shifts', and 'some night shifts' to 'usual/permanent night shifts', there was a significant increasing trend in the risk of incident AF (P for trend 0.013). Usual or permanent night shifts were associated with the highest risk [hazard ratio (HR) 1.16, 95% confidence interval (CI) 1.02-1.32]. Considering a person's lifetime work schedule and compared with shift workers never working nights, participants with a duration over 10 years and an average 3-8 nights/month frequency of night shift work exposure possessed higher AF risk (HR 1.18, 95% CI 0.99-1.40 and HR 1.22, 95% CI 1.02-1.45, respectively). These associations between current and lifetime night shifts and AF were not modified by genetic predisposition to AF. Usual/permanent current night shifts, ≥10 years and 3-8 nights/month of lifetime night shifts were significantly associated with a higher risk of incident CHD (HR 1.22, 95% CI 1.11-1.35, HR 1.37, 95% CI 1.20-1.58 and HR 1.35, 95% CI 1.18-1.55, respectively). These associations in stroke and HF were not significant. Both current and lifetime night shift exposures were associated with increased AF risk, regardless of genetic AF risk. Night shift exposure also increased the risk of CHD but not stroke or HF. Whether decreasing night shift work frequency and duration might represent another avenue to improve heart health during working life and beyond warrants further study.

Noise Exposure Levels from Extended Workshifts

Noise exposure level is the magnitude used to assess the risk of occupational hearing loss. For that reason, its correct measurement and interpretation are of utmost importance. A common practice is to perform the measurement during a representative period of time, generally during an entire workshift, and to assume that the acoustic environment repeats for the rest of the weeks, months, and years. Unfortunately, this assumption is not always accurate. This paper focuses on workshifts of durations other than 8 hours. It presents a novel approach when dealing with seasonal workers and those active for only part of the year. Keywords: Equivalentlevel, hearing loss, shift duration, exposure duration, seasonal workers. Read more →

Guiding principles for determining work shift duration and addressing the effects of work shift duration on performance, safety, and health: guidance from the American Academy of Sleep Medicine and the Sleep Research Society.

Risks associated with fatigue that accumulates during work shifts have historically been managed through working time arrangements that specify fixed maximum durations of work shifts and minimum durations of time off. By themselves, such arrangements are not sufficient to curb risks to performance, safety, and health caused by misalignment between work schedules and the biological regulation of waking alertness and sleep. Science-based approaches for determining shift duration and mitigating associated risks, while addressing operational needs, require: (1) a recognition of the factors contributing to fatigue and fatigue-related risks; (2) an understanding of evidence-based countermeasures that may reduce fatigue and/or fatigue-related risks; and (3) an informed approach to selecting workplace-specific strategies for managing work hours. We propose a series of guiding principles to assist stakeholders with designing a shift duration decision-making process that effectively balances the need to meet operational demands with the need to manage fatigue-related risks.

Guiding principles for determining work shift duration and addressing the effects of work shift duration on performance, safety, and health: guidance from the American Academy of Sleep Medicine and the Sleep Research Society.

Risks associated with fatigue that accumulates during work shifts have historically been managed through working time arrangements that specify fixed maximum durations of work shifts and minimum durations of time off. By themselves, such arrangements are not sufficient to curb risks to performance, safety, and health caused by misalignment between work schedules and the biological regulation of waking alertness and sleep. Science-based approaches for determining shift duration and mitigating associated risks, while addressing operational needs, require: (1) a recognition of the factors contributing to fatigue and fatigue-related risks; (2) an understanding of evidence-based countermeasures that may reduce fatigue and/or fatigue-related risks; and (3) an informed approach to selecting workplace-specific strategies for managing work hours. We propose a series of guiding principles to assist stakeholders with designing a shift duration decision-making process that effectively balances the need to meet operational demands with the need to manage fatigue-related risks.

Letter to the Editor: Landsbergis et al (2019) Titled "Work Exposures and Musculoskeletal Disorders Among Railroad Maintenance-of-Way Workers".

Letter to the Editor: Landsbergis et al (2019) Titled "Work Exposures and Musculoskeletal Disorders Among Railroad Maintenance-of-Way Workers".

Association of Rotating Night Shift Work with Body Fat Percentage and Fat Mass Index among Female Steelworkers in North China.

The aim of this study was to evaluate the associations of rotating night shift work with body fat percentage (BF%) and fat mass index (FMI). A cross-sectional study was conducted among 435 female steelworkers, aged 26–57 years in Tangshan, China. BF% was assessed via bioelectrical impedance analysis and FMI was calculated. Different exposure metrics of night shift work were used to examine the effects of night shift work on BF% and FMI. The duration (years), cumulative number (nights), and cumulative length of night shifts (hours) were positively correlated with FMI and BF%, and these relationships were independent of body mass index (BMI). Compared with day workers, night shift workers with an average frequency of night shifts >7 nights/month (odds ratio (OR) 2.50, 95% confidence interval (CI) 1.17 to 5.35) and percentage of hours on night shifts >30% (OR 2.55, 95% CI 1.21 to 5.39) had elevated odds of obesity (BF% ≥ 35.0%). Nonobese night shift workers by the BMI criterion should also be alert to the risk of the excess accumulation of body fat, which is actually responsible for most obesity-associated adverse health consequences. Health interventions for related populations need to be improved, which is currently more focused on overall weight control.

Evaluation of Environmental Conditions on Self-Selected Work and Heat Stress in Wildland Firefighting.

The purpose of this study was to evaluate heat stress occurring in wildfire management activities with variable environmental conditions. Direct observation and real-time wireless physiological monitoring allowed for weather and physiological metrics, including heart rate, core temperature (Tc), skin temperature, and physiological strain index (PSI), of male (n=193) and female (n=28) wildland firefighters (WLFFs) to be recorded during wildfire management activities. Accelerometry data were used to categorize intensity level of activity. Ambient temperature and relative humidity values were used to compute the heat index (HI; n=3891 h) and divided into quartiles (Q1: 13.3-25.1°C; Q2: 25.2-26.4°C; Q3: 26.5-28.9°C; Q4: 29.0-49.1°C). Activity levels remained relatively constant across all HI quartiles. The percentage of time spent performing moderate/vigorous activities was lowest during the hotter Q4 (Q1: 3%; Q2: 2%; Q3: 2%; Q4: 1%). Heart rate, Tc, PSI, and skin temperature associations with HI varied by resource type. Sixty-one percent of WLFFs (n=134) experienced a Tc ≥38.0°C, and 50% of WLFFs (n=111) experienced a PSI ≥6.0. Heat stress was prevalent as WLFFs performed job tasks of varying intensities in all ambient conditions. Spontaneous bouts of arduous labor, duration of work shifts, and other occupation characteristics present the possibility for substantial durations of hyperthermia, although no heat-related injuries occurred in this study. Despite chronic exposure to rugged sloped terrain, load carriage, and environmental conditions, self-regulation and individual attention to managing work:rest appears to be the primary management strategy in mitigating excessive accumulation of body heat in this occupation.

"There are no band-aids for emotions": The development of thinking about emotional harm.

An understanding of harm is central to social and cognitive development, but harm largely has been conceptualized as physical damage or injury. Less research focuses on children's judgments of harm to others' internal well-being (emotional harms). We asked 5- to 10-year-old children (N = 456, 50% girls, 50% boys; primarily tested in Central New York, with socioeconomic diversity, but limited racial/ethnic or linguistic diversity) to compare emotional and physical harms. In Experiment 1, children compared simple harms (intended and completed) and then scenarios in which the perpetrator's intention did not match the outcome (intended emotional harm, but caused physical harm, or vice-versa). Assessments of the severity of emotional (vs. physical) harm increased with age and depended on the perpetrator's intentions. In Experiment 2, children saw emotional and physical harms that were: Simple (intended and completed); Incomplete (intended, but not completed); or Accidental (not intended, but completed). Children evaluated physical and emotional harms in isolation and then compared the two. Judgments of the relative severity of emotional harm increased with age, but only when intentions and outcomes were both present. This reflected an increase with age in children's perceptions that emotional harm was hurtful, whereas perceptions of physical harm were relatively stable across development. With age, children also increasingly associated emotional harms with longer-term impacts (being remembered and reoccurring). These findings suggest reasoning about the severity, underlying intentions, and duration of emotional harm shifts with age. The results hold implications for moral development, law and psychology, and emotional-harm-related interventions including those addressing bullying. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Night work and incidence of Parkinson’s disease in the Danish Nurse Cohort

ObjectivesEvidence on the association between night work and Parkinson’s disease (PD) is sparse and conflicting, calling for more definitive studies.MethodsWe included 20 138 female nurses from the Danish Nurse Cohort...

Responses of Manx Shearwaters to Handicapping and Its Implications for the Coordination of Care

Seabirds care for their offspring in remote breeding colonies where foraging sites are distant and may be unpredictable, and where chicks are left unaccompanied for extended periods during their parents’ foraging trips, leaving them vulnerable to predation or starvation. One way to mitigate this risk is for individuals to coordinate parenting duties with their partner. Many biparental and cooperatively breeding species are now known to coordinate their care, though the mechanisms underlying this are not well understood. In Manx shearwaters (Puffinus puffinus), both parents alternate shifts of incubation in a coordinated manner. To resolve which processes may underlie this routine, we imposed a wing-loading handicap on parents to reduce their foraging efficiency, forcing them to choose between an extended foraging trip or to return to the nest before their condition has recovered to optimal levels. We found that handicapped parents took significantly longer trips than normal, to which their partner responded by lengthening their incubation shift, suggesting shift durations are not pre-determined. However, the duration of foraging trips and the mass at which foraging birds returned to the nest appeared to be mediated by the condition of the partner. These results suggest that while foraging trip duration is largely driven by the need for the foraging bird to recoup its own condition losses, information-transfer between the parents may facilitate a more cooperative mechanism whereby the decisions made by foraging birds still account for the condition of their partner.

299 Limited Time for Sleep in Night Shift Workers is associated with Risk of Insomnia and Shift Work Disorder

Abstract Introduction Sleep deficiency is a severe problem faced by night shift workers. Approximately one-third of night workers report insomnia during daytime sleep and excessive sleepiness during nighttime work; when severe, these symptoms characterize shift work disorder (SWD). Difficulty sustaining 7 to 9 hours of sleep during the daytime is partly due to a circadian drive for wakefulness. Not much is known, however, about how non-work activities contribute to the inability to obtain recovery sleep. We sought to explore how much time night workers are able to allocate for daytime sleep, and how this relates to insomnia-like symptoms and the likelihood of developing SWD. Methods Night shift workers (n=452, 19–69 years old, 54% men) from various occupations who worked at least four night shifts per month completed an online survey. This included questions related to shift duration, hours per workday of non-optional non-work activities, self-rated sleep need, the Insomnia Severity Index (ISI) and a validated 4-item SWD screening questionnaire. For each participant, we calculated the duration of work plus non-optional activities and compared the remaining available time for sleep to their self-described sleep need. Non-parametric Chi-square analyses and Pearson correlations were conducted. Results On average, shift duration was 8.9±1.6 hours, non-optional activities were 3.6±2.9 hours, and sleep need was 7.6±1.6 hours, leaving 15% of shift workers with insufficient free time to obtain the amount of sleep they needed. The percentage of workers at high risk for SWD was significantly greater among those who did not have enough free time for sleep compared to those whose schedules allowed sufficient sleep time (72% vs. 42%; χ2=20.2, p<0.0001). We also found that shift workers with insufficient free time for sleep reported higher insomnia severity (r2=-0.20, p<0.0001). Conclusion About 15% of night workers have non-optional activities outside work that limit their time to obtain sufficient sleep, and this contributes to greater insomnia-like symptoms and increased risk for SWD. Future research should focus on understanding what these non-optional activities are and whether they differ between night and day workers. These insights will enable personalized countermeasures to maximize the sleep and health of shift workers. Support (if any) Supported by US NIH grant R01-AG044416.

Divergent transcriptional response to mTORC1‐mediated nutrient signaling in mouse liver and skeletal muscle

The mechanistic target of rapamycin complex 1 (mTORC1) has a central role in balancing nutrients and growth factors with metabolic processes. Many of its mediated processes can vary between tissues to meet specific metabolic demands. Here we examine this process in mouse liver and skeletal muscle to characterize the tissue specific transcriptional response to the mTORC1 inhibitor rapamycin. We performed RNA-seq analysis on fasted tissue over a refeeding time course with and without rapamycin. Since the canonical regulation of mTORC1 is active in response to nutrient abundance and inactive during nutrient deprivation, our goal was to capture the transcriptional elements that are regulated by mTORC1 activation in both tissues. We observed altered expression of major metabolic pathways in the liver response to rapamycin but not in skeletal muscle. In addition, our time course analysis revealed a distinct increase in expression shift duration in response to rapamycin. Together our data show a clear tissue specific transcriptional response to rapamycin and a differential expression pattern that's detection was made possible through our analysis of multiple time points.

Automatic Transmission Upshift Control Using a Linearized Reduced-Order Model-Based LQR Approach

<div class="section abstract"><div class="htmlview paragraph">Automatic transmission (AT) upshift control performance in terms of shift duration and comfort can be improved during the inertia phase by coordinating the off-going clutch together with oncoming clutch and engine torque. The performance improvement is highest in low gear shifts (i.e., for high ratio steps), which are typically performed with open torque converter. In this paper, a discrete-time, linear quadratic regulation (LQR) is applied during the upshift inertia phase, as it provides an optimal multi-input/multi-output control action with respect to the prescribed cost function. The LQR law is based on a reduced-order drivetrain model, which is applicable to actual transmissions characterized by a limited number of available state measurements. The reduced-order model includes the linearized torque converter model. The shift duration is ensured by precise tracking of a linear-like oncoming clutch slip speed reference profile. To facilitate the tracking accuracy, the LQR law is extended by an integral action. A clipped optimal approach is applied to account for the clutch energy passivity. By using a set of differently weighted conflicting criteria in the discrete cost function, including shift duration, comfort, and efficiency, Pareto frontiers are obtained based on post-processing the multi-run simulation results. The Pareto frontiers are compared with benchmark frontiers determined off-line by applying a multi-objective genetic algorithm-based control parameter optimization relying on full-order, nonlinear drivetrain model. It is shown that the LQR approach results in comparable Pareto frontiers to those obtained by multi-objective optimization.</div></div>