4,064 research outputs found

    Nonparametric estimation and specification testing of a two-factor interest rate model

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    We propose a simple, flexible approach to nonparametric estimation and specification testing for a two-factor interest rate model. These methods are illustrated with a Monte Carlo experiment and an empirical example.Nonparametric local linear estimation, Two-factor term structure models, Model specification tests

    Testing for Bivariate Stochastic Dominance Using Inequality Restrictions

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    In this paper, we propose of a test of bivariate stochastic dominance using a generalized framework for testing inequality constraints. Unlike existing tests, this test has the advantage of utilizing the covariance structure of the estimates of the joint distribution functions. The performance of our proposed test is examined by way of a Monte Carlo experiment. We also consider an empirical example which utilizes household survey data on income and health status.Stochastic dominance, inequality restrictions, multidimensional welfare

    Energy harvesting from train vibrations

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    In this paper, linear mechanical oscillators are designed to harvest energy from train-induced vibrations. The harvested energy could be used, for example, to charge sensors mounted on the rail track for structural health monitoring. The dominant frequencies due to a passing train are determined for a specific train and speed from a recorded acceleration time-history. Using a simple model of an oscillator, the total energy harvested for the passage of one train is calculated. The stiffness, and hence the tuning frequency of the device, is varied in simulations to determine the optimum frequency at which to tune the device for a constant value of mass and damping in the device. Further simulations are conducted to investigate the power that could be harvested from multiple oscillators tuned at several dominant frequencies, and their performances are analysed and compared. The constraint for maximum relative displacement is considered in the design of each harvester, and this is adopted to assure that the amplitude of the oscillation is finite and does not exceed the physical size of the device. The robustness of the harvester is also analysed for different train speeds

    Fatigue and the Female Nurse: A Narrative Review of the Current State of Research and Future Directions

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    Background: The female nurse exhibits a multitude of personal and environmental characteristics that renders this population especially prone to fatigue. The consequences of fatigue in nurses are widespread and impactful at the personal, organizational, and societal levels. These include high injury rates and burnout in the nurse and poor patient and organizational outcomes. Objective: This article discusses the implications of fatigue in female nurses, including the impacts of fatigue across multiple entities (e.g., worker, patient, organization). It also reviews the current state of the research, including recent work on nurse fatigue and work schedule characteristics, and key areas for future work that would help empirically establish approaches to counter the detrimental and widespread effects of fatigue. Method: A narrative literature review was conducted resulting from an analysis of the literature limited to peer-reviewed studies. Results: A confluence of factors combines to elevate the prevalence and risk of fatigue in the female nurse. Numerous measures have established that performance-based fatigue results from nursing work schedules in nurses. Data also demonstrate that fatigue accumulates across successive shifts. Recent evidence supports the use of objective fatigue measures, including psychomotor reaction time and muscle function-related variables. Current gaps in the literature are delineated in the text. Conclusions: Strategic and well-designed research studies, as well as recent technological advances in fatigue tracking tools have the potential to help workers, administrators, and organizations develop fatigue management programs that could reduce the heavy burdens of fatigue on a multitude of health, safety, and economical outcomes. The influences of fatigue and its symptoms are of epidemic proportions. The consequences associated with fatigue apply indiscriminately to individuals of all ages, and across all social, educational, ethnic, racial, and economic demographics.1,2 Unsurprisingly, reports have revealed that at least some degree of fatigue is to be found in nearly all of the general or working populations.3ā€“5 Since the symptoms of fatigue are presented along a continuum from negligible to severe67 The core factors that appear to contribute to the rampant impact of fatigue are (1) the high total prevalence of fatigue symptoms that are manifested in the population at large (e.g., Bultmann et al.3 reported that only 2% of a population of 12,095 identified as being completely free of fatigue) and (2) the relatively high proportion (āˆ¼40%ā€“60%) of adults that exhibit severe fatigue levels.6,8,9 Although fatigue has been the subject of many reports across a multitude of domainsā€”including physiology, psychology, sports science, military, and so onā€”relatively little has been reviewed with recent updates regarding physical fatigue in the context of the female nursing worker, and updates for future research directions would be warranted and timely. Given that the female nurse exhibits some unique vulnerabilities to fatigue and its consequencesā€”due to interactions among biological, occupational, and environmental factorsā€”further exploration into this area is of interest for researchers and practitioners. Thus, the aims of this review were to provide an overview of the implications of fatigue focusing on issues pertinent to the female nurse, a brief update on the current state of the research with a particular focus within the work schedule domain, and to provide future directions for research that could shed more light on areas less explored that remain poorly understood. This review will be focused on hospital-based nurses and aides, since this group accounts for a majority (āˆ¼60%) of working nurses and is characterized by unconventional, demanding work schedules (i.e., where 12-hour and rotating shifts are typical).1

    Does Work-Induced Fatigue Accumulate Across Three Compressed 12 Hour Shifts in Hospital Nurses and Aides?

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    Fatigue-related impairments in the nursing workforce contribute to a multitude of health, safety, and economic consequences at the individual, organizational and societal levels. Long and compressed work schedules are commonly worked in the healthcare industry, but more research is needed to understand the cumulative effects of multiple work shifts on physiology-based performance outcomes in nurses. The purpose of this study was to compare the effects of a single nursing work shift versus three compressed (one every 24 hours) 12 hour shifts on performance-based fatigue in nurses and aides. Twenty-six fulltime hospital working nurses and aides (age = 36.1 Ā± 13.3 years) reported to the lab for testing before, immediately after working a single 12 hour shift, and after working three 12 hour shifts in a 72 hour period. Outcome measures included vigilance-based reaction time, lapses of attention, and muscle function assessments (lower and upper body muscle strength, explosive strength and vertical jump performance). All variables except hand grip strength showed a significant decline following the three work shifts. The psychomotor vigilance reaction time and lapses of attention variables also generally showed a significant decline from the end of shift one to the end of shift three, indicting an accumulation of fatigue in these metrics with increasing number of shifts worked. Muscle function variables responded early in the duty cycle, showing a significant decline after a single work shift, but did no further decline by the end of the third shift. These findings use objective measures to substantiate that fatigue impairments occur from working a single 12 hour shift, and in several instances, increase further with more successive work shifts. Caution should be employed by personnel and administrators with work schedules involving multiple compressed 12 hour shifts. Fatigue management strategies may be used to improve risks and consequences from fatigue-related mishaps, and this study reports several variables that appear sensitive to identifying and tracking fatigue in this population

    Effect of Surface Stability on Core Muscle Activity During Dynamic Resistance Exercises

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    The purpose of this study was to compare core muscle activity during resistance exercises performed on stable ground versus an unstable surface and to examine whether lifting at different relative intensities affects core muscle activity levels. Twelve trained men performed four different movements including the deadlift, back squat, military press, and curl. Surface electromyography (EMG) was utilized to assess the activity of the rectus abdominis, external oblique, transversus abdominis, and erector spinae muscles. Participants performed each movement under three separate conditions including standing on stable ground with 50% of their one repetition maximum (1-RM), standing on a BOSU balance trainer with 50% of their 1-RM and, standing on stable ground with 75% of their 1-RM. The following muscles exhibited greater activity during the 75% 1-RM condition than all other conditions: the transversus abdominis (TA) and external oblique (EO) muscles during the deadlift; the rectus abdominis (RA) during the squat; the TA, RA, and EO during the press, and TA and erector spinae (ES) during the curl. The ES muscle during the press movement and EO during the squat movement were more active during the BOSU 50% 1-RM condition than the stable 50% 1-RM condition. Healthy individuals might consider performing the military press, curl, squat and deadlift movements with higher intensity resistances while standing on stable ground to incur higher widespread muscle activity of the core region

    State Welfare-to-Work Policies for People with Disabilities

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    This study represents a first attempt to provide a nationwide overview of welfare-to-work policies for individuals with disabilities and caregivers. The major findings of this report are: (c) The majority of states have changed their work participation policies to require participation among some individuals with disabilities and caregivers who were previously exempt. (c) States are in the early stages of making decisions about who should be required to participate in welfare-to-work services, who should be expected to move off welfare within 60 months, and what services will best help recipients achieve this objective

    Beyond and beneath the hierarchical market economy: global production and working-class conflict in Argentina's automobile industry

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    This paper argues that the hierarchical market economy (HME) category does not provide an adequate starting point for addressing capitalist diversity in Latin America. Building from a critical perspective on the global commodity chain (GCC) and global production network (GPN) approaches, it instead considers the impact of firmsā€™ transnational relations and the often neglected role of working-class struggles. It will argue that capitalist diversity can only be understood at the nexus of these ostensibly global and local phenomena; and by specifying the strategic decisions taken by firms in Argentinaā€™s automobile industry, it will account for the failure of that sector. Finally, it examines the role of working-class struggles in the industry in CĆ³rdoba, Argentina, arguing that these were vital in shaping the specific and unstable form of capitalist diversity in Argentina, as well as potential alternatives to it

    Interaction Between Age and Fatigue on Antagonist Muscle Coactivation During an Acute Post-Fatigue Recovery Phase

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    This study investigated the age-related changes in antagonist muscle coactivation of the biceps femoris (BF) during an acute recovery period following a leg extensor fatiguing protocol. Twenty-three young (mean Ā± SD: age = 25.1 Ā± 3.0 years) and twenty-three old men (age = 71.5 Ā± 3.9 years) participated. Surface electromyography (sEMG) was recorded from the BF muscles for antagonist muscle coactivation. Testing invovled participants performing leg extension isometric maximal voluntary contractions (MVCs) and isokinetic MVCs at 240Ā°ā€¢s-1 at baseline (Pre) and again after the fatigue protocol at 0 (Post0), 7 (Post7), 15 (Post15), and 30 (Post30) minutes post fatigue. Root mean square (RMS) values were computed from the BF sEMG and were calculated as the first 200 ms from onset for the isometric (IsomCoact200ms) and dynamic isokinetic 240Ā°ā€¢s-1 (DynCoact200ms) MVCs, and for the final 10Ā° of the leg extension (DynCoact10Ā°) on the isokinetic 240Ā°ā€¢-1 MVCs. Two-way ANOVAs [age group (young vs. old x time (Pre vs. Post0 vs. Post7 vs. Post15 vs. Post30)] showed that DynCoact200ms had an effect for time (p = 0.018), with greater antagonist coactivation in Pre than Post0 (p = 0.009) and recovering by Post7 (p = 0.011) with no group differences. Dyn Coact10Ā° had no age x time interaction (p = 0.070), but had a main effect for time (p = 0.020) with the Post0 being lower than the Pre. However, for this variable the young group showed a more severe Pre to Post0 fatigue decline (-45.9%) than the old group (-6.7%) indicating this may be a more sensitive variable for capturing age-related antagonist coactivation post-fatigue responses. Leg extensor fatigue affects some BF coactivation sEMG variables more than others, and any altered post-fatigue coactivation response recovers rapidly ( \u3c 7 min) from baseline levels

    Potential Benefits of a Minimal Dose Eccentric Resistance Training Paradigm to Combat Sarcopenia and Age-Related Muscle and Physical Function Deficits in Older Adults

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    The ability of older adults to perform activities of daily living is often limited by the ability to generate high mechanical outputs. Therefore, assessing and devloping maximal neuromuscular capacity is essential for determining age-related risk for functional decline as well as the effectiveness of therapeutic interventions. Interventions designed to enhance neuromuscular capacities underpinning maximal mechanical outputs could positively impact functional performace in daily life. Unfortunately, \u3c 10% of older adults meet the current resistance training guidelines. It has recently been proposed that a more minimal dose RT model may help engage a greater proprotion of older adults, so that they may realize the benefits of RT. Eccentric exercise offers some promising qualities for such an approach due to its efficiency in overloading contractions that can induce substantial neuromuscular adaptations. When used in a minimal dose RT paradigm, eccentric-based RT may be a particularly promising approach for older adults that can efficiently improve muscle mass, strength, and function capacities and overall health is through heightened exercise tolerance which would favor greater exercise participation in older adult populations. Therefore, our perspective article will discuss the implications of using a minimal dose, submaximal (i.e., low intensity) multi-join eccentric resistance training paradigm as a potentially effective, and yet currently underutilized, means to efficiently improve neuromuscular capacities and function for older adults
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