The comparison of the influence of centrifugal forces and the Sagnac effect on a rotating whispering gallery modes resonators

NASA Astrophysics Data System (ADS)

Filatov, Yuri V.; Shalymov, Egor V.; Venediktov, Vladimir Yu.; Dmitrieva, Anna D.

2016-10-01

The parameters of whispering gallery modes resonators can be significantly modified under the action of external factors, for instance, in the case of resonator movement. The effects, which take place in the moving resonators of whispering gallery modes, can be employed for measuring of the angular velocity. In this work we was compared the influence of centrifugal forces and the Sagnac effect on the eigenfrequencies (wavelengths) of whispering gallery modes resonators. Also work is devoted mutual relationships of the effects.

The effect of ill health and socioeconomic status on labor force exit and re-employment: a prospective study with ten years follow-up in the Netherlands.

PubMed

Schuring, Merel; Robroek, Suzan J W; Otten, Ferdy W J; Arts, Coos H; Burdorf, Alex

2013-03-01

The aim of this study was to investigate the effect of ill health and socioeconomic status on labor force exit due to unemployment, early retirement, disability pension, or becoming economically inactive. A secondary objective was to investigate the effect of ill health and socioeconomic status on return to work. A representative sample of the Dutch working population (N=15 152) was selected for a prospective study with ten years follow-up (93 917 person-years). Perceived health and individual and household characteristics were measured at baseline with the Permanent Quality of Life Survey (POLS) during 1999-2002. Statistics Netherlands ascertained employment status monthly from January 1999 to December 2008. Cox proportional hazards analyses were used to determine the factors that predicted labor force exit and return to work. Ill health increased the likelihood of labor force exit into unemployment [hazard ratio (HR) 1.89], disability pension (HR 6.39), and early retirement (HR 1.20), but was not a determinant of becoming economically inactive (HR 1.07). Workers with low socioeconomic status were, even after adjusting for ill health, more likely to leave the labor force due to unemployment, disability pension, and economic inactivity. Workers with ill health at baseline were less likely to return to work after unemployment (HR 0.75) or disability pension (HR 0.62). Socioeconomic status did not influence re-employment. Ill health is an important determinant for entering and maintaining paid employment. Workers with lower education were at increased risk for health-based selection out of paid employment. Policies to improve labor force participation, especially among low socioeconomic level workers, should protect workers with health problems against exclusion from the labor force.

Health work force planning in the 90s, Part II: Enough in the right place at the right time?

PubMed

Turner, L A; Ostbye, T; Pederson, L L

1993-01-01

The focus of this discussion has been on achieving a distribution of health care professionals that meets the objective of making health services available to the total population. The need for a systematic approach to planning, not only for the health care work force, but for the system in general, has been recognized as the highest priority for the health care systems of industrialized countries for over a decade. Overall, the goal of health care work force planning the world over is "to provide the right type of education and training for the right number and type of people needed to render effectively and safely the right types of service when and where required by the population." What is needed is a readiness to evaluate existing service delivery models, to retain those found to be effective and efficient, and to re-direct resources from outdated or ineffective strategies into new approaches found to better meet this goal. We need to envision the health care work force as a whole; work toward making it as efficient as possible, and thereby maintain our national commitment to universal health care.

Tech Prep II: Implementation Final Report.

ERIC Educational Resources Information Center

Brown, Jane A.

This document contains the final progress report on a tech prep implementation project and the Work Force Challenge 2000 Report developed during the project. The final report lists these major accomplishments: approximately 1,500 educators in grades K-12 were provided information concerning future global issues in the work force and the effects in…

Effects of the Recent Recession on the Labor Force Participation of Nonmetropolitan Women.

ERIC Educational Resources Information Center

O'Leary, Jeanne M.

Expanding work opportunities, changing family structure, double digit inflation, and relaxed attitudes toward the appropriateness of women's work outside the home have contributed to increased labor force participation of women in recent years. Recent studies indicate that despite traditional attitudes ascribed to rural areas, trends in increasing…

Occupational health issues affecting the pharmaceutical sales force.

PubMed

Harris, G; Mayho, G; Page, L

2003-09-01

The sales force forms a significant sub-population in the pharmaceutical industry workforce. Role and organizational characteristics, such as isolation, peripatetic working and car travel and the psychosocial and ergonomic hazards related to work tasks, present particular occupational health risks. To review the occupational risks associated with peripatetic sales force work and evidence for the effectiveness of preventive interventions. We carried out a review of the available literature between 1990 and 2003. The following hazards were identified as significant and worthy of further investigation for this occupational group: driving on company business; violence in the workplace; stress; ergonomic issues; and mobile phone use. To ensure effective prevention and management of employee health problems, specific health management strategies and interventions must be developed to meet the occupational health needs of this group.

Modeling the influence of the Casimir force on the pull-in instability of nanowire-fabricated nanotweezers

NASA Astrophysics Data System (ADS)

Farrokhabadi, Amin; Mokhtari, Javad; Rach, Randolph; Abadyan, Mohamadreza

2015-09-01

The Casimir force can strongly interfere with the pull-in performance of ultra-small structures. The strength of the Casimir force is significantly affected by the geometries of interacting bodies. Previous investigators have exclusively studied the effect of the Casimir force on the electromechanical instability of nanostructures with planar geometries. However no work has yet considered this effect on the pull-in instability of systems with cylindrical geometries such as nanotweezers fabricated from nanotube/nanowires. In our present work, the influence of the Casimir attraction on the electrostatic response and pull-in instability of nanotweezers fabricated from cylindrical conductive nanowires/nanotubes is theoretically investigated. An asymptotic solution, based on scattering theory, is applied to consider the effect of vacuum fluctuations in the theoretical model. The Euler-Bernoulli beam model is employed, in conjunction with the size-dependent modified couple stress continuum theory, to derive the governing equation of the nanotweezers. The governing nonlinear equations are solved by two different approaches, i.e., the modified Adomian-Padé method (MAD-Padé) and a numerical solution. Various aspects of the problem, i.e., the variation of pull-in parameters, effect of geometry, coupling between the Casimir force and size dependency effects and comparison with the van der Waals force regime are discussed.

Ulnar neuropathy and ulnar neuropathy-like symptoms in relation to biomechanical exposures assessed by a job exposure matrix: a triple case-referent study.

PubMed

Svendsen, Susanne Wulff; Johnsen, Birger; Fuglsang-Frederiksen, Anders; Frost, Poul

2012-11-01

We aimed to evaluate relations between occupational biomechanical exposures and (1) ulnar neuropathy confirmed by electroneurography (ENG) and (2) ulnar neuropathy-like symptoms with normal ENG. In this triple case-referent study, we identified all patients aged 18-65 years, examined with ENG at a neurophysiological department on suspicion of ulnar neuropathy, 2001-2007. We mailed a questionnaire to 546 patients with ulnar neuropathy, 633 patients with ulnar neuropathy-like symptoms and two separate groups of community referents, matched on sex, age and primary care centre (risk set sampling). The two patient groups were also compared to each other directly. We constructed a Job Exposure Matrix to provide estimates of exposure to non-neutral postures, repetitive movements, hand-arm vibrations and forceful work. Conditional and unconditional logistic regressions were used. The proportion who responded was 59%. Ulnar neuropathy was related to forceful work with an exposure-response pattern reaching an OR of 3.85 (95% CI 2.04 to 7.24); non-neutral postures strengthened effects of forceful work. No relation was observed with repetitive movements. Ulnar neuropathy-like symptoms were related to repetitive movements with an OR of 1.89 (95% CI 1.01 to 3.52) in the highest-exposure category (≥2.5 h/day); forceful work was unrelated to the outcome. Ulnar neuropathy and ulnar neuropathy-like symptoms differed with respect to associations with occupational biomechanical exposures. Findings suggested specific effects of forceful work on the ulnar nerve. Thus, results corroborated the importance of an electrophysiological diagnosis when evaluating risk factors for ulnar neuropathy. Preventive effects may be achieved by reducing biomechanical exposures at work.

Finding the Effective Mass and Spring Constant of a Force Probe from Simple Harmonic Motion

ERIC Educational Resources Information Center

Greene, Nathaniel R.; Gill, Tom; Eyerly, Stephen

2016-01-01

Force probes are versatile tools in the physics lab, but their internal workings can introduce artifacts when measuring rapidly changing forces. The Dual-Range Force Sensor by Vernier uses strain gage technology to measure force, based on the bending of a beam. Strain gages along the length of the beam change resistance as the beam bends. The…

Derivation of energy-based base shear force coefficient considering hysteretic behavior and P-delta effects

NASA Astrophysics Data System (ADS)

Ucar, Taner; Merter, Onur

2018-01-01

A modified energy-balance equation accounting for P-delta effects and hysteretic behavior of reinforced concrete members is derived. Reduced hysteretic properties of structural components due to combined stiffness and strength degradation and pinching effects, and hysteretic damping are taken into account in a simple manner by utilizing plastic energy and seismic input energy modification factors. Having a pre-selected yield mechanism, energy balance of structure in inelastic range is considered. P-delta effects are included in derived equation by adding the external work of gravity loads to the work of equivalent inertia forces and equating the total external work to the modified plastic energy. Earthquake energy input to multi degree of freedom (MDOF) system is approximated by using the modal energy-decomposition. Energy-based base shear coefficients are verified by means of both pushover analysis and nonlinear time history (NLTH) analysis of several RC frames having different number of stories. NLTH analyses of frames are performed by using the time histories of ten scaled ground motions compatible with elastic design acceleration spectrum and fulfilling duration/amplitude related requirements of Turkish Seismic Design Code. The observed correlation between energy-based base shear force coefficients and the average base shear force coefficients of NLTH analyses provides a reasonable confidence in estimation of nonlinear base shear force capacity of frames by using the derived equation.

The Influence of Altering Push Force Effectiveness on Upper Extremity Demand during Wheelchair Propulsion

PubMed Central

Rankin, Jeffery W.; Kwarciak, Andrew M.; Richter, W. Mark; Neptune, Richard R.

2010-01-01

Manual wheelchair propulsion has been linked to a high incidence of overuse injury and pain in the upper extremity, which may be caused by the high load requirements and low mechanical efficiency of the task. Previous studies have suggested that poor mechanical efficiency may be due to a low effective handrim force (i.e. applied force that is not directed tangential to the handrim). As a result, studies attempting to reduce upper extremity demand have used various measures of force effectiveness (e.g. fraction effective force, FEF) as a guide for modifying propulsion technique, developing rehabilitation programs and configuring wheelchairs. However, the relationship between FEF and upper extremity demand is not well understood. The purpose of this study was to use forward dynamics simulations of wheelchair propulsion to determine the influence of FEF on upper extremity demand by quantifying individual muscle stress, work and handrim force contributions at different values of FEF. Simulations maximizing and minimizing FEF resulted in higher average muscle stresses (23% and 112%) and total muscle work (28% and 71%) compared to a nominal FEF simulation. The maximal FEF simulation also shifted muscle use from muscles crossing the elbow to those at the shoulder (e.g. rotator cuff muscles), placing greater demand on shoulder muscles during propulsion. The optimal FEF value appears to represent a balance between increasing push force effectiveness to increase mechanical efficiency and minimizing upper extremity demand. Thus, care should be taken in using force effectiveness as a metric to reduce upper extremity demand. PMID:20674921

Light-Induced Pulling and Pushing by the Synergic Effect of Optical Force and Photophoretic Force

NASA Astrophysics Data System (ADS)

Lu, Jinsheng; Yang, Hangbo; Zhou, Lina; Yang, Yuanqing; Luo, Si; Li, Qiang; Qiu, Min

2017-01-01

Optical force, coming from momentum exchange during light-matter interactions, has been widely utilized to manipulate microscopic objects, though mostly in vacuum or in liquids. By contrast, due to the light-induced thermal effect, photophoretic force provides an alternative and effective way to transport light-absorbing particles in ambient gases. However, in most cases these forces work independently. Here, by employing the synergy of optical force and photophoretic force, we propose and experimentally demonstrate a configuration which can drive a micron-size metallic plate moving back and forth on a tapered fiber with supercontinuum light in ambient air. Optical pulling and oscillation of the metallic plate are experimentally realized. The results might open exhilarating possibilities in applications of optical driving and energy conversion.

Numerical simulation of airflow around the evaporator in the closed space

NASA Astrophysics Data System (ADS)

Puchor, Tomáš; Banovčan, Roman; Lenhard, Richard

2018-06-01

The article deals with a numerical simulation of the forced airflow around a evaporator with the finned tubes in the electrotechnical box, by finite volume method in the program ANSYS Workbench. The work contains an analysis of the impact of forced airflow on the evaporator with the various seated the electrical components. The aim of the work is to find out the most effective way of heat dissipation by forced convection from the electrical components in the closed space with lowest pressure loss.

Force Modelling in Orthogonal Cutting Considering Flank Wear Effect

NASA Astrophysics Data System (ADS)

Rathod, Kanti Bhikhubhai; Lalwani, Devdas I.

2017-05-01

In the present work, an attempt has been made to provide a predictive cutting force model during orthogonal cutting by combining two different force models, that is, a force model for a perfectly sharp tool plus considering the effect of edge radius and a force model for a worn tool. The first force model is for a perfectly sharp tool that is based on Oxley's predictive machining theory for orthogonal cutting as the Oxley's model is for perfectly sharp tool, the effect of cutting edge radius (hone radius) is added and improve model is presented. The second force model is based on worn tool (flank wear) that was proposed by Waldorf. Further, the developed combined force model is also used to predict flank wear width using inverse approach. The performance of the developed combined total force model is compared with the previously published results for AISI 1045 and AISI 4142 materials and found reasonably good agreement.

Economic and demographic effects on working women in Latin America.

PubMed

Psaharopoulos, G; Tzannatos, Z

1993-01-01

This analysis of women's work conditions in Latin America includes a description of general trends in female labor force participation in 15 Latin American countries based on census data between 1950 and 1990. Also examined are pay differentials by gender and whether gender alone or individual characteristics of women workers accounted for the sex-wage gap. More extensive treatment is available in the author's other 1992 publications. Trends indicate that marriage and children were important factors determining whether women were in the labor force or not. The probability of being in the labor force was reduced by 50% for married women, and each child reduced the probability by 5%. When marriage and children were controlled for, age had a positive effect on probability of participation. Urban female heads of household had a positive effect on women's labor force participation. The higher a woman's educational qualification, the greater the probability of being in the work force. Earnings increased with increased educational level. An increase of 1 year of schooling for women contributed to an increase in female earnings of 13.1. Investment in education for women has a higher yield for women than for men. Policies that directly or indirectly improve women's employment opportunities, particularly when families are being formed, can have wide distributional effects. Also unresolved was an explanation for why female participation increased during periods of recession and why women are rewarded more for educational effort than men. The suggestion was that public sector employment, which included many women in the labor force, is distorting results.

Research on key factors and their interaction effects of electromagnetic force of high-speed solenoid valve.

PubMed

Liu, Peng; Fan, Liyun; Hayat, Qaisar; Xu, De; Ma, Xiuzhen; Song, Enzhe

2014-01-01

Analysis consisting of numerical simulations along with lab experiments of interaction effects between key parameters on the electromagnetic force based on response surface methodology (RSM) has been also proposed to optimize the design of high-speed solenoid valve (HSV) and improve its performance. Numerical simulation model of HSV has been developed in Ansoft Maxwell environment and its accuracy has been validated through lab experiments. Effect of change of core structure, coil structure, armature structure, working air gap, and drive current on the electromagnetic force of HSV has been analyzed through simulation model and influence rules of various parameters on the electromagnetic force have been established. The response surface model of the electromagnetic force has been utilized to analyze the interaction effect between major parameters. It has been concluded that six interaction factors including working air gap with armature radius, drive current with armature thickness, coil turns with side pole radius, armature thickness with its radius, armature thickness with side pole radius, and armature radius with side pole radius have significant influence on the electromagnetic force. Optimal match values between coil turns and side pole radius; armature thickness and side pole radius; and armature radius and side pole radius have also been determined.

Research on Key Factors and Their Interaction Effects of Electromagnetic Force of High-Speed Solenoid Valve

PubMed Central

Fan, Liyun; Xu, De; Ma, Xiuzhen; Song, Enzhe

2014-01-01

Analysis consisting of numerical simulations along with lab experiments of interaction effects between key parameters on the electromagnetic force based on response surface methodology (RSM) has been also proposed to optimize the design of high-speed solenoid valve (HSV) and improve its performance. Numerical simulation model of HSV has been developed in Ansoft Maxwell environment and its accuracy has been validated through lab experiments. Effect of change of core structure, coil structure, armature structure, working air gap, and drive current on the electromagnetic force of HSV has been analyzed through simulation model and influence rules of various parameters on the electromagnetic force have been established. The response surface model of the electromagnetic force has been utilized to analyze the interaction effect between major parameters. It has been concluded that six interaction factors including working air gap with armature radius, drive current with armature thickness, coil turns with side pole radius, armature thickness with its radius, armature thickness with side pole radius, and armature radius with side pole radius have significant influence on the electromagnetic force. Optimal match values between coil turns and side pole radius; armature thickness and side pole radius; and armature radius and side pole radius have also been determined. PMID:25243217

The Relationship between Work-Life Conflict/Work-Life Balance and Operational Effectiveness in the Canadian Forces

DTIC Science & Technology

2006-12-01

life conflict/ work - life balance and performance has primarily used non-military populations . Accordingly, the findings that are discussed in this... using CF personnel but also more generally to the research on work - life conflict/ work - life balance . As discussed previously, most of the recent research...conflict/ work - life balance and operational effectiveness in CF members. Work -family conflict,

On the structure of attractors for discrete, periodically forced systems with applications to population models

Treesearch

James F. Selgrade; James H. Roberds

2001-01-01

This work discusses the effects of periodic forcing on attracting cycles and more complicated attractors for autonomous systems of nonlinear difference equations. Results indicate that an attractor for a periodically forced dynamical system may inherit structure from an attractor of the autonomous (unforced) system and also from the periodicity of the forcing. In...

Women and Work-Place Stress. ERIC Digest.

ERIC Educational Resources Information Center

Long, Bonita C.

With North American women joining the work force in record numbers, the effect of employment on women's well-being is gaining attention. This digest examines various stressors affecting women in the work world and some actions companies can take to alleviate these stressors. While some studies show that work has detrimental effects on some…

Dissipation effects in mechanics and thermodynamics

NASA Astrophysics Data System (ADS)

Güémez, J.; Fiolhais, M.

2016-07-01

With the discussion of three examples, we aim at clarifying the concept of energy transfer associated with dissipation in mechanics and in thermodynamics. The dissipation effects due to dissipative forces, such as the friction force between solids or the drag force in motions in fluids, lead to an internal energy increase of the system and/or to heat transfer to the surroundings. This heat flow is consistent with the second law, which states that the entropy of the universe should increase when those forces are present because of the irreversibility always associated with their actions. As far as mechanics is concerned, the effects of the dissipative forces are included in Newton’s equations as impulses and pseudo-works.

Force, Velocity, and Work: The Effects of Different Contexts on Students' Understanding of Vector Concepts Using Isomorphic Problems

ERIC Educational Resources Information Center

Barniol, Pablo; Zavala, Genaro

2014-01-01

In this article we compare students' understanding of vector concepts in problems with no physical context, and with three mechanics contexts: force, velocity, and work. Based on our "Test of Understanding of Vectors," a multiple-choice test presented elsewhere, we designed two isomorphic shorter versions of 12 items each: a test with no…

Attitudes toward working mothers: accommodating the needs of mothers in the work force.

PubMed

Albright, A

1992-10-01

More women, including mothers, are part of the work force than ever before. In the workplace, barriers often exist that restrict promotion and advancement of mothers. Mothers often are penalized in attempting to meet the demands of parent and worker roles. Parenting practices have been considered primarily the domain of mothers. However, nurturing may be done effectively by fathers or other motivated adults. Policies of employers must change to accommodate needs of families. Examples of supportive practices may include flexible working hours, parental leave, and on-site child care.

The Mechanization of Work.

ERIC Educational Resources Information Center

Ginzberg, Eli

1982-01-01

Discusses how mechanization of work has been treated by economists, what its effect has been on the past U.S. economy, and what its future effect is likely to be. Emphasizes the impact of mechanization on the shifting structure and character of the labor force and evolution of the work environment. (Author/JN)

The effect of acceleration versus displacement methods on steady-state boundary forces

NASA Technical Reports Server (NTRS)

Mcghee, D. S.

1992-01-01

This study describes the acceleration and displacement methods for use in the recovery of coupled system boundary forces. A simple two degree of freedom system has been used for illustration. The effect of the choice of method for use with indeterminate or over-constrained boundaries has been investigated. It has specifically looked at results from a simple two dimensional beam problem using both methods. Much work has been done on the effect of Craig-Bampton modal truncation system displacements and forces, however, little work has been done on system level modal truncation. The findings of this study indicate that the effect of this system level truncation is significant. This may be particularly true for the 35 Hz system cutoff frequency that is required by the space shuttle. From this study's findings, recommendations for areas of study with space shuttle payload systems are made.

Size, History-Dependent, Activation and Three-Dimensional Effects on the Work and Power Produced During Cyclic Muscle Contractions.

PubMed

Ross, Stephanie A; Ryan, David S; Dominguez, Sebastian; Nigam, Nilima; Wakeling, James M

2018-05-03

Muscles undergo cycles of length change and force development during locomotion, and these contribute to their work and power production to drive body motion. Muscle fibres are typically considered to be linear actuators whose stress depends on their length, velocity, and activation state, and whose properties can be scaled up to explain the function of whole muscles. However, experimental and modelling studies have shown that a muscle's stress additionally depends on inactive and passive tissues within the muscle, the muscle's size, and its previous contraction history. These effects have not been tested under common sets of contraction conditions, especially the cyclic contractions that are typical of locomotion. Here we evaluate the relative effects of size, history-dependent, activation and three-dimensional effects on the work and power produced during cyclic contractions of muscle models. Simulations of muscle contraction were optimized to generate high power outputs: this resulted in the muscle models being largely active during shortening, and inactive during lengthening. As such, the history-dependent effects were dominated by force depression during simulated active shortening rather than force enhancement during active stretch. Internal work must be done to deform the muscle tissue, and to accelerate the internal muscle mass, resulting in reduced power and work that can be done on an external load. The effect of the muscle mass affects the scaling of muscle properties, with the inertial costs of contraction being relatively greater at larger sizes and lower activation levels.

Training and Educating the Work Force in the Nineties: The Rationale for Public/Private Collaboration. Public/Private Ventures. Information Series No. 331.

ERIC Educational Resources Information Center

Smith, Thomas J.; Trist, Carolyn

The need for partnerships among deliverers of training in the public and private sectors has reached a critical point if U.S. businesses are to remain competitive. The work force and workplace are being transformed by demographic trends, economic and employment trends, a growing skills mismatch, and concerns over educational effectiveness. Two…

Making Child Care Work. Report to the 1987 Minnesota Legislature by the Child Care Task Force.

ERIC Educational Resources Information Center

Moriarty, Sheila; And Others

This report makes recommendations to the 1987 Minnesota Legislature on some actions that can be taken to improve Minnesota's child care system and make it work more effectively. The first section of the report documents the growing need for child care, emphasizing the number of children in Minnesota, the number of women in the labor force, changes…

Effects of High School Work Experience a Decade Later: Evidence from the National Longitudinal Survey.

ERIC Educational Resources Information Center

Wright, James D.; Carr, Rhoda

Using a data sample from the National Longitudinal Survey of Youth that included all youths enrolled in high school who were aged 16-19 in 1979, a study tracked the youths' labor force attachment and earnings 12 years later. The study found that students who worked while in high school show increased rates of labor force participation along with…

Women's labor force participation in later life: the effects of early work and family experiences.

PubMed

Pienta, A M; Burr, J A; Mutchler, J E

1994-09-01

The purpose of this study was to develop and evaluate a model of labor force participation among a group of older women in the United States. A comprehensive measure of women's combined work and family experiences across the adult life course was created. Employing data from the 1984 Survey of Income and Program Participation, we applied multinomial logistic regression techniques to examine the association between work-family experiences and later life labor supply. Our findings generally support an attachment hypothesis, showing that women who were the most work-oriented throughout the life course were more likely than women who experienced family-related spells of nonlabor-market activity to participate in the labor force, either full-time or part-time, later in life.

A Discussion of Patient Safety Programs in the United States Air Force Ground Medical Expeditionary Environment and an Analysis of Potential Solutions for Increasing Their Effectiveness

DTIC Science & Technology

2017-05-01

and 4N to work Patient Safety together, and it has worked out fine in our environment .” • “It is my opinion that there needs to be a permanent full...GROUND MEDICAL EXPEDITIONARY ENVIRONMENT AND AN ANALYSIS OF POTENTIAL SOLUTIONS FOR INCREASING THEIR EFFECTIVENESS By: James Lee...DISCUSSION OF PATIENT SAFETY PROGRAMS IN THE UNITED STATES AIR FORCE GROUND MEDICAL EXPEDITIONARY ENVIRONMENT AND AN ANALYSIS OF POTENTIAL SOLUTIONS FOR

Passive Joint Forces Are Tuned to Limb Use in Insects and Drive Movements without Motor Activity

PubMed Central

Ache, Jan M.; Matheson, Thomas

2013-01-01

Summary Background Limb movements are generally driven by active muscular contractions working with and against passive forces arising in muscles and other structures. In relatively heavy limbs, the effects of gravity and inertia predominate, whereas in lighter limbs, passive forces intrinsic to the limb are of greater consequence. The roles of passive forces generated by muscles and tendons are well understood, but there has been little recognition that forces originating within joints themselves may also be important, and less still that these joint forces may be adapted through evolution to complement active muscle forces acting at the same joint. Results We examined the roles of passive joint forces in insect legs with different arrangements of antagonist muscles. We first show that passive forces modify actively generated movements of a joint across its working range, and that they can be sufficiently strong to generate completely passive movements that are faster than active movements observed in natural behaviors. We further demonstrate that some of these forces originate within the joint itself. In legs of different species adapted to different uses (walking, jumping), these passive joint forces complement the balance of strength of the antagonist muscles acting on the joint. We show that passive joint forces are stronger where they assist the weaker of two antagonist muscles. Conclusions In limbs where the dictates of a key behavior produce asymmetry in muscle forces, passive joint forces can be coadapted to provide the balance needed for the effective generation of other behaviors. PMID:23871240

Unsteady motion, finite Reynolds numbers, and wall effect on Vorticella convallaria contribute contraction force greater than the stokes drag.

PubMed

Ryu, Sangjin; Matsudaira, Paul

2010-06-02

Contraction of Vorticella convallaria, a sessile ciliated protozoan, is completed within a few milliseconds and results in a retraction of its cell body toward the substratum by coiling its stalk. Previous studies have modeled the cell body as a sphere and assumed a drag force that satisfies Stokes' law. However, the contraction-induced flow of the medium is transient and bounded by the substrate, and the maximum Reynolds number is larger than unity. Thus, calculations of contractile force from the drag force are incomplete. In this study, we analyzed fluid flow during contraction by the particle tracking velocimetry and computational fluid dynamics simulations to estimate the contractile force. Particle paths show that the induced flow is limited by the substrate. Simulation-based force estimates suggest that the combined effect of the flow unsteadiness, the finite Reynolds number, and the substrate comprises 35% of the total force. The work done in the early stage of contraction and the maximum power output are similar regardless of the medium viscosity. These results suggest that, during the initial development of force, V. convallaria uses a common mechanism for performing mechanical work irrespective of viscous loading conditions. Copyright (c) 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

TOPICAL REVIEW: Aspects of scanning force microscope probes and their effects on dimensional measurement

NASA Astrophysics Data System (ADS)

Yacoot, Andrew; Koenders, Ludger

2008-05-01

The review will describe the various scanning probe microscopy tips and cantilevers used today for scanning force microscopy and magnetic force microscopy. Work undertaken to quantify the properties of cantilevers and tips, e.g. shape and radius, is reviewed together with an overview of the various tip-sample interactions that affect dimensional measurements.

Pump instability phenomena generated by fluid forces

NASA Technical Reports Server (NTRS)

Gopalakrishnan, S.

1985-01-01

Rotor dynamic behavior of high energy centrifugal pumps is significantly affected by two types of fluid forces; one due to the hydraulic interaction of the impeller with the surrounding volute or diffuser and the other due to the effect of the wear rings. The available data on these forces is first reviewed. A simple one degree-of-freedom system containing these forces is analytically solved to exhibit the rotor dynamic effects. To illustrate the relative magnitude of these phenomena, an example of a multistage boiler feed pump is worked out. It is shown that the wear ring effects tend to suppress critical speed and postpone instability onset. But the volute-impeller forces tend to lower the critical speed and the instability onset speed. However, for typical boiler feed pumps under normal running clearances, the wear ring effects are much more significant than the destabilizing hydraulic interaction effects.

A Phenomenological Model and Validation of Shortening Induced Force Depression during Muscle Contractions

PubMed Central

McGowan, C.P.; Neptune, R.R.; Herzog, W.

2009-01-01

History dependent effects on muscle force development following active changes in length have been measured in a number of experimental studies. However, few muscle models have included these properties or examined their impact on force and power output in dynamic cyclic movements. The goal of this study was to develop and validate a modified Hill-type muscle model that includes shortening induced force depression and assess its influence on locomotor performance. The magnitude of force depression was defined by empirical relationships based on muscle mechanical work. To validate the model, simulations incorporating force depression were developed to emulate single muscle in situ and whole muscle group leg extension experiments. There was excellent agreement between simulation and experimental values, with in situ force patterns closely matching the experimental data (average RMS error < 1.5 N) and force depression in the simulated leg extension exercise being similar in magnitude to experimental values (6.0% vs 6.5%, respectively). To examine the influence of force depression on locomotor performance, simulations of maximum power pedaling with and without force depression were generated. Force depression decreased maximum crank power by 20% – 40%, depending on the relationship between force depression and muscle work used. These results indicate that force depression has the potential to substantially influence muscle power output in dynamic cyclic movements. However, to fully understand the impact of this phenomenon on human movement, more research is needed to characterize the relationship between force depression and mechanical work in large muscles with different morphologies. PMID:19879585

Theoretical modeling of the effect of Casimir attraction on the electrostatic instability of nanowire-fabricated actuators

NASA Astrophysics Data System (ADS)

Mokhtari, J.; Farrokhabadi, A.; Rach, R.; Abadyan, M.

2015-04-01

The presence of the quantum vacuum fluctuations, i.e. the Casimir attraction, can strongly affect the performance of ultra-small actuators. The strength of the Casimir force is significantly influenced by the geometries of interacting bodies. Previous research has exclusively studied the impact of the vacuum fluctuations on the instability of nanoactuators with planar geometries. However, no work has yet considered this phenomenon in actuators fabricated from nanowires/nanotubes with cylindrical geometries. In our present work, the influence of the Casimir attraction on the electrostatic stability of nanoactuators fabricated from cylindrical conductive nanowire/nanotube is investigated. The Dirichlet mode is considered and an asymptotic solution, based on scattering theory, is applied to consider the effect of vacuum fluctuations in the theoretical model. The size-dependent modified couple stress theory is employed to derive the constitutive equation of the actuator. The governing nonlinear equations are solved by two different approaches, i.e. the finite difference method and modified Adomian-Padé method. Various aspects of the problem, i.e. comparison with the van der Waals force regime, the variation of instability parameters, effect of geometry and coupling between the Casimir force and size dependency are discussed. This work is beneficial to determine the impact of Casimir force on nanowire/nanotube-fabricated actuators.

Stiffness, working stroke, and force of single-myosin molecules in skeletal muscle: elucidation of these mechanical properties via nonlinear elasticity evaluation.

PubMed

Kaya, Motoshi; Higuchi, Hideo

2013-11-01

In muscles, the arrays of skeletal myosin molecules interact with actin filaments and continuously generate force at various contraction speeds. Therefore, it is crucial for myosin molecules to generate force collectively and minimize the interference between individual myosin molecules. Knowledge of the elasticity of myosin molecules is crucial for understanding the molecular mechanisms of muscle contractions because elasticity directly affects the working and drag (resistance) force generation when myosin molecules are positively or negatively strained. The working stroke distance is also an important mechanical property necessary for elucidation of the thermodynamic efficiency of muscle contractions at the molecular level. In this review, we focus on these mechanical properties obtained from single-fiber and single-molecule studies and discuss recent findings associated with these mechanical properties. We also discuss the potential molecular mechanisms associated with reduction of the drag effect caused by negatively strained myosin molecules.

Intimate Partner Violence in the Canadian Armed Forces: The Role of Family Stress and Its Impact on Well-Being.

PubMed

Skomorovsky, Alla; Hujaleh, Filsan; Wolejszo, Stefan

2015-07-01

Unique demands of military life (e.g., deployment) can have a significant impact on family life. Although most families cope effectively with military life stressors, some may have difficulty adjusting, experiencing marital conflicts, and violence. Evidence suggests that unmanaged occupational demands may create family stress by interfering with efforts to fulfill family duties. This study examined the effects of work-family conflict and marital satisfaction on intimate violence experienced by Canadian Armed Forces members, and the impact of such violence on their psychological well-being (N = 525). Regression analyses showed that both work-family conflict and marital satisfaction were unique and significant predictors of emotional and physical violence experienced by Canadian Armed Forces members. Moreover, bootstrapping analyses demonstrated that marital satisfaction partially mediated the relationship between work-family and family-work conflicts and intimate partner violence. The results point to the importance of examining the interrelationship between family stress and occupational stressors when exploring interpersonal violence and its psychological impact on military personnel. Reprint & Copyright © 2015 Association of Military Surgeons of the U.S.

Relationships between Mechanical Variables in the Traditional and Close-Grip Bench Press.

PubMed

Lockie, Robert G; Callaghan, Samuel J; Moreno, Matthew R; Risso, Fabrice G; Liu, Tricia M; Stage, Alyssa A; Birmingham-Babauta, Samantha A; Stokes, John J; Giuliano, Dominic V; Lazar, Adrina; Davis, DeShaun L; Orjalo, Ashley J

2017-12-01

The study aim was to determine relationships between mechanical variables in the one-repetition maximum (1RM) traditional bench press (TBP) and close-grip bench press (CGBP). Twenty resistance-trained men completed a TBP and CGBP 1RM. The TBP was performed with the preferred grip; the CGBP with a grip width of 95% biacromial distance. A linear position transducer measured: lift distance and duration; work; and peak and mean power, velocity, and force. Paired samples t-tests (p < 0.05) compared the 1RM and mechanical variables for the TBP and CGBP; effect sizes (d) were also calculated. Pearson's correlations (r; p < 0.05) computed relationships between the TBP and CGBP. 1RM, lift duration, and mean force were greater in the TBP (d = 0.30-3.20). Peak power and velocity was greater for the CGBP (d = 0.50-1.29). The 1RM TBP correlated with CGBP 1RM, power, and force (r = 0.685-0.982). TBP work correlated with CGBP 1RM, lift distance, power, force, and work (r = 0.542-0.931). TBP power correlated with CGBP 1RM, power, force, velocity, and work (r = 0.484-0.704). TBP peak and mean force related to CGBP 1RM, power, and force (r = 0.596-0.980). Due to relationships between the load, work, power, and force for the TBP and CGBP, the CGBP could provide similar strength adaptations to the TBP with long-term use. The velocity profile for the CGBP was different to that of the TBP. The CGBP could be used specifically to improve high-velocity, upper-body pushing movements.

Relationships between Mechanical Variables in the Traditional and Close-Grip Bench Press

PubMed Central

Callaghan, Samuel J.; Moreno, Matthew R.; Risso, Fabrice G.; Liu, Tricia M.; Stage, Alyssa A.; Birmingham-Babauta, Samantha A.; Stokes, John J.; Giuliano, Dominic V.; Lazar, Adrina; Davis, DeShaun L.; Orjalo, Ashley J.

2017-01-01

Abstract The study aim was to determine relationships between mechanical variables in the one-repetition maximum (1RM) traditional bench press (TBP) and close-grip bench press (CGBP). Twenty resistance-trained men completed a TBP and CGBP 1RM. The TBP was performed with the preferred grip; the CGBP with a grip width of 95% biacromial distance. A linear position transducer measured: lift distance and duration; work; and peak and mean power, velocity, and force. Paired samples t-tests (p < 0.05) compared the 1RM and mechanical variables for the TBP and CGBP; effect sizes (d) were also calculated. Pearson’s correlations (r; p < 0.05) computed relationships between the TBP and CGBP. 1RM, lift duration, and mean force were greater in the TBP (d = 0.30-3.20). Peak power and velocity was greater for the CGBP (d = 0.50-1.29). The 1RM TBP correlated with CGBP 1RM, power, and force (r = 0.685-0.982). TBP work correlated with CGBP 1RM, lift distance, power, force, and work (r = 0.542-0.931). TBP power correlated with CGBP 1RM, power, force, velocity, and work (r = 0.484-0.704). TBP peak and mean force related to CGBP 1RM, power, and force (r = 0.596-0.980). Due to relationships between the load, work, power, and force for the TBP and CGBP, the CGBP could provide similar strength adaptations to the TBP with long-term use. The velocity profile for the CGBP was different to that of the TBP. The CGBP could be used specifically to improve high-velocity, upper-body pushing movements. PMID:29339982

Gyration-radius dynamics in structural transitions of atomic clusters.

PubMed

Yanao, Tomohiro; Koon, Wang S; Marsden, Jerrold E; Kevrekidis, Ioannis G

2007-03-28

This paper is concerned with the structural transition dynamics of the six-atom Morse cluster with zero total angular momentum, which serves as an illustrative example of the general reaction dynamics of isolated polyatomic molecules. It develops a methodology that highlights the interplay between the effects of the potential energy topography and those of the intrinsic geometry of the molecular internal space. The method focuses on the dynamics of three coarse variables, the molecular gyration radii. By using the framework of geometric mechanics and hyperspherical coordinates, the internal motions of a molecule are described in terms of these three gyration radii and hyperangular modes. The gyration radii serve as slow collective variables, while the remaining hyperangular modes serve as rapidly oscillating "bath" modes. Internal equations of motion reveal that the gyration radii are subject to two different kinds of forces: One is the ordinary force that originates from the potential energy function of the system, while the other is an internal centrifugal force. The latter originates from the dynamical coupling of the gyration radii with the hyperangular modes. The effects of these two forces often counteract each other: The potential force generally works to keep the internal mass distribution of the system compact and symmetric, while the internal centrifugal force works to inflate and elongate it. Averaged fields of these two forces are calculated numerically along a reaction path for the structural transition of the molecule in the three-dimensional space of gyration radii. By integrating the sum of these two force fields along the reaction path, an effective energy curve is deduced, which quantifies the gross work necessary for the system to change its mass distribution along the reaction path. This effective energy curve elucidates the energy-dependent switching of the structural preference between symmetric and asymmetric conformations. The present methodology should be of wide use for the systematic reduction of dimensionality as well as for the identification of kinematic barriers associated with the rearrangement of mass distribution in a variety of molecular reaction dynamics in vacuum.

Gyration-radius dynamics in structural transitions of atomic clusters

NASA Astrophysics Data System (ADS)

Yanao, Tomohiro; Koon, Wang S.; Marsden, Jerrold E.; Kevrekidis, Ioannis G.

2007-03-01

This paper is concerned with the structural transition dynamics of the six-atom Morse cluster with zero total angular momentum, which serves as an illustrative example of the general reaction dynamics of isolated polyatomic molecules. It develops a methodology that highlights the interplay between the effects of the potential energy topography and those of the intrinsic geometry of the molecular internal space. The method focuses on the dynamics of three coarse variables, the molecular gyration radii. By using the framework of geometric mechanics and hyperspherical coordinates, the internal motions of a molecule are described in terms of these three gyration radii and hyperangular modes. The gyration radii serve as slow collective variables, while the remaining hyperangular modes serve as rapidly oscillating "bath" modes. Internal equations of motion reveal that the gyration radii are subject to two different kinds of forces: One is the ordinary force that originates from the potential energy function of the system, while the other is an internal centrifugal force. The latter originates from the dynamical coupling of the gyration radii with the hyperangular modes. The effects of these two forces often counteract each other: The potential force generally works to keep the internal mass distribution of the system compact and symmetric, while the internal centrifugal force works to inflate and elongate it. Averaged fields of these two forces are calculated numerically along a reaction path for the structural transition of the molecule in the three-dimensional space of gyration radii. By integrating the sum of these two force fields along the reaction path, an effective energy curve is deduced, which quantifies the gross work necessary for the system to change its mass distribution along the reaction path. This effective energy curve elucidates the energy-dependent switching of the structural preference between symmetric and asymmetric conformations. The present methodology should be of wide use for the systematic reduction of dimensionality as well as for the identification of kinematic barriers associated with the rearrangement of mass distribution in a variety of molecular reaction dynamics in vacuum.

Particle force model effects in a shock-driven multiphase instability

NASA Astrophysics Data System (ADS)

Black, W. J.; Denissen, N.; McFarland, J. A.

2018-05-01

This work presents simulations on a shock-driven multiphase instability (SDMI) at an initial particle volume fraction of 1% with the addition of a suite of particle force models applicable in dense flows. These models include pressure-gradient, added-mass, and interparticle force terms in an effort to capture the effects neighboring particles have in non-dilute flow regimes. Two studies are presented here: the first seeks to investigate the individual contributions of the force models, while the second study focuses on examining the effect of these force models on the hydrodynamic evolution of a SDMI with various particle relaxation times (particle sizes). In the force study, it was found that the pressure gradient and interparticle forces have little effect on the instability under the conditions examined, while the added-mass force decreases the vorticity deposition and alters the morphology of the instability. The relaxation-time study likewise showed a decrease in metrics associated with the evolution of the SDMI for all sizes when the particle force models were included. The inclusion of these models showed significant morphological differences in both the particle and carrier species fields, which increased as particle relaxation times increased.

Note: Effect of the parasitic forced vibration in an atom gravimeter

NASA Astrophysics Data System (ADS)

Chen, Le-Le; Luo, Qin; Zhang, Heng; Duan, Xiao-Chun; Zhou, Min-Kang; Hu, Zhong-Kun

2018-06-01

The vibration isolator usually plays an important role in atom interferometry gravimeters to improve their sensitivity. We show that the parasitic forced vibration of the Raman mirror, which is induced by external forces acting on the vibration isolator, can cause a bias in atom gravimeters. The mechanism of how this effect induces an additional phase shift in our interferometer is analyzed. Moreover, modulation experiments are performed to measure the dominant part of this effect, which is caused by the magnetic force between the passive vibration isolator and the coil of the magneto-optic trap. In our current apparatus, this forced vibration contributes a systematic error of -2.3(2) × 10-7 m/s2 when the vibration isolator works in the passive isolation mode. Even suppressed with an active vibration isolator, this effect can still contribute -6(1) × 10-8 m/s2; thus, it should be carefully considered in precision atom gravimeters.

Interrelation of the effects caused by the rotation of the whispering gallery modes resonator

NASA Astrophysics Data System (ADS)

Dmitriyeva, Anna D.; Filatov, Yuri V.; Shalymov, Egor V.; Venediktov, Vladimir Yu.

2016-11-01

Optical whispering gallery modes resonators are characterized by unique properties: ultrahigh quality factor, small amount of the modes and small size. It allows to use them in compact high-precision measuring devices. In particular these resonators can be used in the composition of gyros. For today all researches, devoted to the application of the whispering gallery modes resonators in gyros, deals only with one of induced by the rotation effects (Sagnac effect or the influence of centrifugal forces on the resonator size). In this work we study the interrelation of the effects caused by the rotation of the whispering gallery modes resonator. Also in work we consider the possibility of joint application of both effects (the influence of centrifugal forces and Sagnac effect) for measuring angular velocity.

Investigation of holder pressure and size effects in micro deep drawing of rectangular work pieces driven by piezoelectric actuator.

PubMed

Aminzahed, Iman; Mashhadi, Mahmoud Mosavi; Sereshk, Mohammad Reza Vaziri

2017-02-01

Micro forming is a manufacturing process to fabricate micro parts with high quality and a cost effective manner. Deep drawing could be a favorable method for production of complicated parts in macro and micro sizes. In this paper piezoelectric actuator is used as a novel approach in the field of micro manufacturing. Also, in current work, investigations are conducted with four rectangular punches and blanks with various thicknesses. Blank holder pressure effects on thickness distributions, punch force, and springback are studied. According to the results of this work, increasing of blank holder pressure in scaled deep drawing, in contrast to thickness of drawn part, leads to decrease in the punch forces and springback. Furthermore, it is shown that in micro deep drawing, the effects of holder pressure on mentioned parameters can be ignored. Copyright © 2016 Elsevier B.V. All rights reserved.

Leaving Too Many Children Behind: A Demographer's View on the Neglect of America's Youngest Children.

ERIC Educational Resources Information Center

Hodgkinson, Harold L.

This paper draws on demographic data on children spotlighted in the 2000 Census (called the Childrens Class of 2000) to examine how forces like poverty and family instability work to prevent equality of opportunity in school and in life. The paper describes some programs and techniques that effectively reduce the effects of these forces and…

Understanding Work and Literacy: (E)merging Discourses at Work. Research into Practice Series Number 7.

ERIC Educational Resources Information Center

Castleton, Geraldine; Ovens, Carolyn; Ralston, Deborah

The nature and effects of current common understandings of the relationship between work and literacy were examined along with the typical design and objectives of workplace literacy programs for members of Australia's work force. Special attention was paid to the following topics: changing demands of work and literacy at work; discourses of…

Workforce Development.

ERIC Educational Resources Information Center

1999

This document contains four symposium papers on work force development. "Effects of Two Different Learning Paths on School-to-Work Transition" (Esther Van Der Schoot) discusses a Dutch study documenting that the following items make a difference in the school-to-work transition: learning path, curriculum characteristics, individual…

Characterization of Antisticking Layers for UV Nanoimprint Lithography Molds with Scanning Probe Microscopy

NASA Astrophysics Data System (ADS)

Masaaki Kurihara,; Sho Hatakeyama,; Noriko Yamada,; Takeya Shimomura,; Takaharu Nagai,; Kouji Yoshida,; Tatsuya Tomita,; Morihisa Hoga,; Naoya Hayashi,; Hiroyuki Ohtani,; Masamichi Fujihira,

2010-06-01

Antisticking layers (ASLs) on UV nanoimprint lithography (UV-NIL) molds were characterized by scanning probe microscopies (SPMs) in addition to macroscopic analyses of work of adhesion and separation force. Local physical properties of the ASLs were measured by atomic force microscopy (AFM) and friction force microscopy (FFM). The behavior of local adhesive forces measured with AFM on several surfaces was consistent with that of work of adhesion obtained from contact angle. The ASLs were coated by two different processes, i.e., one is a vapor-phase process and the other a spin-coating process. The homogeneity of the ASLs prepared by the vapor-phase process was better than that of those prepared by the spin-coating process. In addition, we measured the thicknesses of ASL patterns prepared by a lift-off method to investigate the effect of the ASL thicknesses on critical dimensions of the molds with ASLs and found that this effect is not negligible.

Work and retirement among a cohort of older men in the United States, 1966-1983.

PubMed

Hayward, M D; Grady, W R

1990-08-01

Multivariate increment-decrement working life tables are estimated for a cohort of older men in the United States for the period 1966-1983. The approach taken allows multiple processes to be simultaneously incorporated into a single model, resulting in a more realistic portrayal of a cohort's late-life labor force behavior. In addition, because the life table model is developed from multivariate hazard equations, we identify the effects of sociodemographic characteristics on the potentially complex process by which the labor force career is ended. In contrast to the assumed homogeneity of previous working life table analyses, the present study shows marked differences in labor force mobility and working and nonworking life expectancy according to occupation, class of worker, education, race, and marital status. We briefly discuss the implications of these findings for inequities of access to retirement, private and public pension consumption, and future changes in the retirement process.

A technique for studying cardiac myosin dynamics using optical tweezers

NASA Astrophysics Data System (ADS)

Paolino, Michael; Migirditch, Sam; Nesmelov, Yuri; Hester, Brooke; Appalachian State Biophysics; Optical Sciences Facility Team

A primary protein involved in human muscle contraction is myosin, which exists in α- and β- isoforms. Myosin exerts forces on actin filaments when ATP is present, driving muscle contraction. A significant decrease in the population of cardiac α-myosin has been linked to heart failure. It is proposed that slow β-myosin in a failing heart could, through introduction of a drug, be made to mimic the action of α-myosin, thereby improving cardiac muscle performance. In working towards testing this hypothesis, the focus of this work is to develop a technique to measure forces exerted by myosin on actin using optical tweezers. An actin-myosin arrangement is constructed between two optically trapped polystyrene microspheres. The displacement of a microsphere is monitored when ATP is introduced, and the force responsible is measured. With this achieved, we can then modify the actin-myosin arrangement, for example with varying amounts of α- and β- myosin and test the effects on forces exerted. In this work, assemblies of actin and myosin molecules and preliminary force measurements are discussed. North Carolina Space Grant.

Living the reality of forced sex work: perspectives from young migrant women sex workers in northern Vietnam.

PubMed

Rushing, Rosanne; Watts, Charlotte; Rushing, Sharon

2005-01-01

Young women are often lured or forced into selling sex as a result of migrating from rural to urban areas to find work. In this setting, they are exposed to high-risk situations, which may leave them vulnerable to exploitation. Using interviews with young migrant women currently working as sex workers in northern Vietnam, we recorded the perspectives of their initiation into sex work and life as a sex worker. The study found that high levels of forced sex and sexual exploitation were experienced by the majority of the young women interviewed. The young women describe their entry into sex work, first sexual experience (intercourse), violence, and condom negotiation and use. Although access to health care was available, the young women perceived the stigma attached to sex work as a barrier to receiving health care, and thus, preferred health education and care from peers. Health education programs focusing on peer education and support are essential for protecting and empowering these young women. In addition, policies and programs must work toward effective strategies to protect young migrant women.

Experimental investigation on the dissipative and elastic characteristics of a yaw colloidal damper destined to carbody suspension of a bullet train

NASA Astrophysics Data System (ADS)

Suciu, B.; Tomioka, T.

2016-09-01

Yaw damper represents a major source of excitation for flexural vibration of the railway carbody. In order to reduce transmissibility of such undesired excitation, yaw damper should allow for large force transmission at low working frequencies, but should behave as vibration isolator at high working frequencies. Unfortunately, the yaw oil damper (OD), which is nowadays in service, has poor intrinsic elastic capabilities and provides damping forces varying as a power function versus the piston speed. Since colloidal damper (CD) has intrinsic elastic capabilities and larger damping forces at lower excitation frequencies, it occurs as an attractive alternative solution to traditional yaw dampers. In this work, a yaw CD destined to carbody suspension of a bullet train was designed and manufactured; then, its dynamic characteristics, produced by both the frictional and colloidal effects, were evaluated from the experimental results, obtained during horizontal vibration tests, performed on a ball-screw shaker. Compared to the corresponding classical yaw OD, the trial yaw CD allowed for: weight reduction of 31.6%; large damping force, dissipated energy and spring constant at long piston stroke under low excitation frequency; low damping force, dissipated energy and spring constant at short piston stroke under high excitation frequency. Elastic properties were justified by introducing a model for the spring constant that included the effect of pore size distribution.

Working with Allies and Partners: A Cost-Based Analysis of U.S. Air Forces in Europe

DTIC Science & Technology

2012-01-01

Reports & Bookstore Make a charitable contribution Limited Electronic Distribution Rights This document and trademark(s) contained herein are protected by...67 A.13. The Effect ...That Building Partnerships and Partner Capacity Can Have on the Ability to Work Effectively with Partner Countries

On the Effects of Wives' Employment on Marital Adjustment and Companionship.

ERIC Educational Resources Information Center

Locksley, Anne

1980-01-01

No evidence was found for any effect of wives' employment or degree of interest in their work activity on marital adjustment and companionship. The extensive controversy over wives' increasing labor-force participation has resulted from unwarranted assumptions about the impact of wives' working on marital adjustment. (Author)

Bending stiffness, torsional stability, and insertion force of cementless femoral stems.

PubMed

Incavo, S J; Johnson, C C; Churchill, D L; Beynnon, B D

2001-04-01

In cementless total hip arthroplasty, increased femoral stem flexibility and decreased fracture propensity are desirable characteristics. The slotting and tapering of the stem have been introduced to achieve this. These features should not, however, be allowed to interfere with the ability of the distal stem to provide initial mechanical stability, especially under rotation. This study was done to investigate the ability of slotted and tapered stem designs to reduce stiffness and insertion force while still maintaining adequate torsional strength. The torsional strength, maximum insertion force, and insertional work of straight, slotted, and taper stems were measured by inserting each type into rigid polyurethane foam and torque testing to failure. Bending stiffness of each stem design was calculated using numerical methods. When compared to a straight stem, a unislot stem has similar torsional strength, maximum insertional force, and work of insertion. The bending stiffness is decreased by 19% to 82% depending on the bending direction. A trislot design decreased torque strength by 29%, maximal insertion force by 36%, and work by 11%. Bending stiffness was decreased by 74% and was not dependent on bending direction. A 0.5-mm taper decreased torque strength by 11% and insertional work by 14%. No difference was seen in maximum insertional force. We conclude that the design features studied (slots and taper) are effective in decreasing stem stiffness and reducing fracture propensity.

Health shocks adversely impact participation in the labour force in a working age population: a longitudinal analysis.

PubMed

Carter, Kristie N; Gunasekara, Fiona Imlach; Blakely, Tony; Richardson, Ken

2013-06-01

It is well understood that health affects labour force participation (LFP). However, much of the published research has been on older (retiring age) populations and using subjective health measures. This paper aims to assess the impact of an objective measure of 'health shock' (cancer registration or hospitalisation) on LFP in a working age population using longitudinal panel study data and fixed effect regression analyses. Seven waves of data from 2002-09 from the longitudinal Survey of Family, Income and Employment (SoFIE) were used, including working aged individuals who consented to have their survey information linked to health records (n=6,780). Fixed effect conditional logistic regression was used to model the impact of health shocks (hospitalisation or cancer registration) in the previous year on labour force participation at date of annual interview. Models were stratified by gender, age group (25-39 years, 40-54 years) and gender by age group. A health shock was associated with a significantly increased risk of subsequent non-participation in the labour force (odds ratio 1.54, 95%CI 1.30-1.82). Although interactions of age, sex and age by sex with health shock were not statistically significant, the association was largest in younger men and women. Using an objective measure of health, we have shown that a health shock adversely affects subsequent labour force participation. There are a number of policy and practice implications relating to support for working age people who have hospitalisations. © 2013 The Authors. ANZJPH © 2013 Public Health Association of Australia.

Characterization of chemically and enzymatically treated hemp fibres using atomic force microscopy and spectroscopy

NASA Astrophysics Data System (ADS)

George, Michael; Mussone, Paolo G.; Abboud, Zeinab; Bressler, David C.

2014-09-01

The mechanical and moisture resistance properties of natural fibre reinforced composites are dependent on the adhesion between the matrix of choice and the fibre. The main goal of this study was to investigate the effect of NaOH swelling of hemp fibres prior to enzymatic treatment and a novel chemical sulfonic acid method on the physical properties of hemp fibres. The colloidal properties of treated hemp fibres were studied exclusively using an atomic force microscope. AFM imaging in tapping mode revealed that each treatment rendered the surface topography of the hemp fibres clean and exposed the individual fibre bundles. Hemp fibres treated with laccase had no effect on the surface adhesion forces measured. Interestingly, mercerization prior to xylanase + cellulase and laccase treatments resulted in greater enzyme access evident in the increased adhesion force measurements. Hemp fibres treated with sulfonic acid showed an increase in surface de-fibrillation and smoothness. A decrease in adhesion forces for 4-aminotoulene-3-sulfonic acid (AT3S) treated fibres suggested a reduction in surface polarity. This work demonstrated that AFM can be used as a tool to estimate the surface forces and roughness for modified fibres and that enzymatic coupled with chemical methods can be used to improve the surface properties of natural fibres for composite applications. Further, this work is one of the first that offers some insight into the effect of mercerization prior to enzymes and the effect on the surface topography. AFM will be used to selectively screen treated fibres for composite applications based on the adhesion forces associated with the colloidal interface between the AFM tip and the fibre surfaces.

Working Virtually: Transforming the Mobile Workplace. 2nd Edition

ERIC Educational Resources Information Center

Hoefling, Trina

2017-01-01

Remote working is the new reality, and transactional work--provided by freelancers, contract employees or consultants--has increased exponentially. It is forecast that as much as half the labor force will be working independently and virtually by 2020. Most organizations are still grappling with how to effectively manage their virtual staff and…

The Effect of Tool Handle Shape on Hand Muscle Load and Pinch Force in a Simulated Dental Scaling Task

PubMed Central

Dong, Hui; Loomer, Peter; Barr, Alan; LaRoche, Charles; Young, Ed; Rempel, David

2007-01-01

Work-related upper extremity musculoskeletal disorders, including carpal tunnel syndrome, are prevalent among dentists and dental hygienists. An important risk factor for developing these disorders is forceful pinching which occurs during periodontal work such as dental scaling. Ergonomically designed dental scaling instruments may help reduce the prevalence of carpal tunnel syndrome among dental practitioners. In this study, 8 custom-designed dental scaling instruments with different handle shapes were used by 24 dentists and dental hygienists to perform a simulated tooth scaling task. The muscle activity of two extensors and two flexors in the forearm was recorded with electromyography while thumb pinch force was measured by pressure sensors. The results demonstrated that the instrument handle with a tapered, round shape and a 10 mm diameter required the least muscle load and pinch force when performing simulated periodontal work. The results from this study can guide dentists and dental hygienists in selection of dental scaling instruments. PMID:17156742

Aging and the Work Force: Human Resource Strategies. An Information Paper Prepared for Use by the Special Committee on Aging. United States Senate, Ninety-Seventh Congress, Second Session.

ERIC Educational Resources Information Center

Congress of the U.S., Washington, DC. Senate Special Committee on Aging.

This information paper explores the need for age-neutral functional criteria in the human resources management system and the need for managers to review currently accepted employment policies. Population patterns, labor force profiles, and labor force projections are reviewed. The paper examines the effect of retirement policies and considers…

Mathematical Model of HIF-1 alpha Pathway, Oxygen Transport and Hypoxia

DTIC Science & Technology

2017-09-01

interpret experimental data in terms of underlying mechanisms. Such experiments, if quantitative , can also be used to calibrate and further parameterize...Wing Air Force Research Laboratory Wright-Patterson AFB OH 45433-5707 STINFO COPY Work Unit Manager MATTIE.DAV ID.R.123010 1880 Digitally signed by...MONITORING AGENCY NAME(S) AND ADDRESS(ES) Air Force Materiel Command* Air Force Research Laboratory 711th Human Performance Wing Human Effectiveness

Dynamically Consistent Parameterization of Mesoscale Eddies This work aims at parameterization of eddy effects for use in non-eddy-resolving ocean models and focuses on the effect of the stochastic part of the eddy forcing that backscatters and induces eastward jet extension of the western boundary currents and its adjacent recirculation zones.

NASA Astrophysics Data System (ADS)

Berloff, P. S.

2016-12-01

This work aims at developing a framework for dynamically consistent parameterization of mesoscale eddy effects for use in non-eddy-resolving ocean circulation models. The proposed eddy parameterization framework is successfully tested on the classical, wind-driven double-gyre model, which is solved both with explicitly resolved vigorous eddy field and in the non-eddy-resolving configuration with the eddy parameterization replacing the eddy effects. The parameterization focuses on the effect of the stochastic part of the eddy forcing that backscatters and induces eastward jet extension of the western boundary currents and its adjacent recirculation zones. The parameterization locally approximates transient eddy flux divergence by spatially localized and temporally periodic forcing, referred to as the plunger, and focuses on the linear-dynamics flow solution induced by it. The nonlinear self-interaction of this solution, referred to as the footprint, characterizes and quantifies the induced eddy forcing exerted on the large-scale flow. We find that spatial pattern and amplitude of each footprint strongly depend on the underlying large-scale flow, and the corresponding relationships provide the basis for the eddy parameterization and its closure on the large-scale flow properties. Dependencies of the footprints on other important parameters of the problem are also systematically analyzed. The parameterization utilizes the local large-scale flow information, constructs and scales the corresponding footprints, and then sums them up over the gyres to produce the resulting eddy forcing field, which is interactively added to the model as an extra forcing. Thus, the assumed ensemble of plunger solutions can be viewed as a simple model for the cumulative effect of the stochastic eddy forcing. The parameterization framework is implemented in the simplest way, but it provides a systematic strategy for improving the implementation algorithm.

Effects of requested, forced and denied shift schedule change on work ability and health of nurses in Europe -results from the European NEXT-Study.

PubMed

Galatsch, Michael; Li, Jian; Derycke, Hanne; Müller, Bernd Hans; Hasselhorn, Hans Martin

2013-12-05

Previous cross-sectional findings from the European Nurses Early Exit Study (NEXT) show that nurses who were dissatisfied with their work schedule tended to consider leaving the nursing profession. Mediating factors in this decision process may be caused by self-perceived poor work ability and/or health. The aim of this paper is to investigate changes in work ability and general health among nurses in relation to requested, forced and denied change of shift schedule. Longitudinal data from the NEXT Study was used. In total 11,102 nurses from Belgium, Germany, Finland, the Netherlands, Poland, Slovakia, France and Italy completed both the 'basic questionnaire' (t1) and the '12 month follow-up questionnaire' (t2). To examine the time-effect (repeated measures) and the group-effect of five defined groups of nurses on the Work Ability Index (WAI) and general health (SF36), an adjusted 2-way analysis of covariance (ANCOVA) was performed. The nurses who wanted to, but could not change their shifts during the 12 month follow-up had the lowest initial and follow-up scores for WAI (t1: 37.6, t2: 36.6, p <0.001), lowest general health (t1: 63.9, t2: 59.2, p <0.001) and showed the highest decrease in both outcomes. Shift pattern change in line with the nurses' wishes was associated with improved work ability and to a lesser comparatively low extent with increased decline in health scores. A forced change of shift against the nurses' will was significantly associated with a deteriorating work ability and health. The findings would suggest that nurses' desire to change their shift patterns may be an indicator for perceived low work ability and/or low health. The results also indicate that fulfilling nurses' wishes with respect to their shift work pattern may improve their personal resources such as work ability and - to somewhat lesser extent - health. Disregarding nurses' preferences, however, bears the risk for further resource deterioration. The findings imply that shift schedule organization may constitute a valuable preventive tool to promote nurses' work ability and - to lesser extent - their perceived health, not least in aging nursing work forces.

Beyond the School: What Else Educates?

ERIC Educational Resources Information Center

Hansen, Kenneth H., Ed.

Eleven essays explore the educational effects of social forces and agencies outside of the formal school environment. Speakers at the 1977 Chief State School Officers' Institute examined how these social forces can be used to enhance the work of the American school system. Speakers represented schools of education, research institutes, media…

Modeling and experiments of the adhesion force distribution between particles and a surface.

PubMed

You, Siming; Wan, Man Pun

2014-06-17

Due to the existence of surface roughness in real surfaces, the adhesion force between particles and the surface where the particles are deposited exhibits certain statistical distributions. Despite the importance of adhesion force distribution in a variety of applications, the current understanding of modeling adhesion force distribution is still limited. In this work, an adhesion force distribution model based on integrating the root-mean-square (RMS) roughness distribution (i.e., the variation of RMS roughness on the surface in terms of location) into recently proposed mean adhesion force models was proposed. The integration was accomplished by statistical analysis and Monte Carlo simulation. A series of centrifuge experiments were conducted to measure the adhesion force distributions between polystyrene particles (146.1 ± 1.99 μm) and various substrates (stainless steel, aluminum and plastic, respectively). The proposed model was validated against the measured adhesion force distributions from this work and another previous study. Based on the proposed model, the effect of RMS roughness distribution on the adhesion force distribution of particles on a rough surface was explored, showing that both the median and standard deviation of adhesion force distribution could be affected by the RMS roughness distribution. The proposed model could predict both van der Waals force and capillary force distributions and consider the multiscale roughness feature, greatly extending the current capability of adhesion force distribution prediction.

The Effect of Increasing Mass upon Locomotion

NASA Technical Reports Server (NTRS)

DeWitt, John; Hagan, Donald

2007-01-01

The purpose of this investigation was to determine if increasing body mass while maintaining bodyweight would affect ground reaction forces and joint kinetics during walking and running. It was hypothesized that performing gait with increased mass while maintaining body weight would result in greater ground reaction forces, and would affect the net joint torques and work at the ankle, knee and hip when compared to gait with normal mass and bodyweight. Vertical ground reaction force was measured for ten subjects (5M/5F) during walking (1.34 m/s) and running (3.13 m/s) on a treadmill. Subjects completed one minute of locomotion at normal mass and bodyweight and at four added mass (AM) conditions (10%, 20%, 30% and 40% of body mass) in random order. Three-dimensional joint position data were collected via videography. Walking and running were analyzed separately. The addition of mass resulted in several effects. Peak impact forces and loading rates increased during walking, but decreased during running. Peak propulsive forces decreased during walking and did not change during running. Stride time increased and hip extensor angular impulse and positive work increased as mass was added for both styles of locomotion. Work increased at a greater rate during running than walking. The adaptations to additional mass that occur during walking are different than during running. Increasing mass during exercise in microgravity may be beneficial to increasing ground reaction forces during walking and strengthening hip musculature during both walking and running. Future study in true microgravity is required to determine if the adaptations found would be similar in a weightless environment.

Force Model for Control of Tendon Driven Hands

NASA Technical Reports Server (NTRS)

Pena, Edward; Thompson, David E.

1997-01-01

Knowing the tendon forces generated for a given task such as grasping via a model, an artificial hand can be controlled. A two-dimensional force model for the index finger was developed. This system is assumed to be in static equilibrium, therefore, the equations of equilibrium were applied at each joint. Constraint equations describing the tendon branch connectivity were used. Gaussian elimination was used to solve for the unknowns of the Linear system. Results from initial work on estimating tendon forces in post-operative hands during active motion therapy were discussed. The results are important for understanding the effects of hand position on tendon tension, elastic effects on tendon tension, and overall functional anatomy of the hand.

Thermal and chemical treatment of polymer optical fiber Bragg grating sensors for enhanced mechanical sensitivity

NASA Astrophysics Data System (ADS)

Pospori, A.; Marques, C. A. F.; Sáez-Rodríguez, D.; Nielsen, K.; Bang, O.; Webb, D. J.

2017-07-01

An investigation of the thermal annealing effects on the strain, stress, and force sensitivities of polymer optical fiber Bragg grating sensors is performed. We demonstrate for the first time that the fiber annealing can enhance both stress and force sensitivities of Bragg grating sensors, with the possible cause being the molecular relaxation of the polymer when fiber is raised above the β -transition temperature. A simple, cost-effective, but well controlled method for fiber annealing is also presented in this work. In addition, the effects of chemical etching on the strain, stress, and force sensitivities have been investigated. Results show that fiber etching too can increase the force sensitivity, and it can also affect the strain and stress sensitivities of the Bragg grating sensors.

Molecular simulation of gas adsorption and diffusion in a breathing MOF using a rigid force field.

PubMed

García-Pérez, E; Serra-Crespo, P; Hamad, S; Kapteijn, F; Gascon, J

2014-08-14

Simulation of gas adsorption in flexible porous materials is still limited by the slow progress in the development of flexible force fields. Moreover, the high computational cost of such flexible force fields may be a drawback even when they are fully developed. In this work, molecular simulations of gas adsorption and diffusion of carbon dioxide and methane in NH2-MIL-53(Al) are carried out using a linear combination of two crystallographic structures with rigid force fields. Once the interactions of carbon dioxide molecules and the bridging hydroxyls groups of the framework are optimized, an excellent match is found for simulations and experimental data for the adsorption of methane and carbon dioxide, including the stepwise uptake due to the breathing effect. In addition, diffusivities of pure components are calculated. The pore expansion by the breathing effect influences the self-diffusion mechanism and much higher diffusivities are observed at relatively high adsorbate loadings. This work demonstrates that using a rigid force field combined with a minimum number of experiments, reproduces adsorption and simulates diffusion of carbon dioxide and methane in the flexible metal-organic framework NH2-MIL-53(Al).

America's Changing Work Force: Statistics in Brief.

ERIC Educational Resources Information Center

American Association of Retired Persons, Washington, DC.

This booklet provides information about the demographics of the changing work force. It offers an at-a-glance profile of workers age 45 and older and considers likely changes in the work force of the future. The document includes topics such as the composition of the work force of today and tomorrow by age and sex, labor force participation rates,…

Men who work at age 70 or older.

PubMed

Ozawa, Martha N; Lum, Terry Y

2005-01-01

The federal policy on older workers has shifted from the encouragement of early withdrawal from the labor force to the encouragement of continuous participation in the labor force. In this light, it is instructive to investigate the backgrounds of elderly people who work at age 70 or older. This article presents the findings of a study, using data from the 1993 Asset and Health Dynamics of the Oldest Old Study, that investigated the effects of health, economic conditions (net worth, employer-provided pensions, and supplemental medical insurance coverage), education, and spouse's work status on the probability of working among men aged 70 or older. The study addressed the probability of working, the probability of working fulltime and of working part-time, and the probability of being self-employed and of being employed by others. Implications for policy are discussed.

Work force policy perspectives: registered nurses.

PubMed

Friss, L O

1981-01-01

If the decline in full-time labor force participation by registered nurses in hospitals is to be reversed, the issue of equal pay for comparable work must be addressed. Under pressure for cost containment, policies tend to focus on labor force economics rather than on limitations of services. While the two are interrelated, wage policies must be considered independently. This article describes the network which determines how nurse salaries are set: the relationship between the private sector, the general schedule and the Veteran's Administration. The effects of this system are documented, using testimony from a case in the tenth circuit, as well as comparisons with other reference groups: policemen, teachers, laborers, and VA career fields. The evidence suggests that there is a need for policy intervention. Prime areas for action are the comparability practices by governments, particularly in the areas of classification standards and pay setting. Hospital personnel practices which continue past effects of occupational segregation also should be changed.

WORKING AND CARING: THE SIMULTANEOUS DECISION OF LABOR FORCE PARTICIPATION AND INFORMAL ELDERLY AND CHILD SUPPORT ACT IVITIES IN MEXICO*

PubMed Central

van Gameren, Edwin; Velandia Naranjo, Durfari

2016-01-01

We analyze factors determining women’s decisions to participate in the labor market and provide elderly care and nonfinancial support to their (grand)children. We use data from the Mexican Health and Aging Study, a survey of people aged 50 and over, applying a three-equation, reduced-form SUR model. Results suggest that care needs are the driving force behind caregiving activities. Traditional roles also appear to be relevant in the labor force participation decision: women with a closer labor market connection when they were young are more likely to work. Simulations of demographic changes illustrate potential effects for future caregiving and participation rates. PMID:26924883

Design of teleoperation system with a force-reflecting real-time simulator

NASA Technical Reports Server (NTRS)

Hirata, Mitsunori; Sato, Yuichi; Nagashima, Fumio; Maruyama, Tsugito

1994-01-01

We developed a force-reflecting teleoperation system that uses a real-time graphic simulator. This system eliminates the effects of communication time delays in remote robot manipulation. The simulator provides the operator with predictive display and feedback of computed contact forces through a six-degree of freedom (6-DOF) master arm on a real-time basis. With this system, peg-in-hole tasks involving round-trip communication time delays of up to a few seconds were performed at three support levels: a real image alone, a predictive display with a real image, and a real-time graphic simulator with computed-contact-force reflection and a predictive display. The experimental results indicate the best teleoperation efficiency was achieved by using the force-reflecting simulator with two images. The shortest work time, lowest sensor maximum, and a 100 percent success rate were obtained. These results demonstrate the effectiveness of simulated-force-reflecting teleoperation efficiency.

Disposable soft 3 axis force sensor for biomedical applications.

PubMed

Chathuranga, Damith Suresh; Zhongkui Wang; Yohan Noh; Nanayakkara, Thrishantha; Hirai, Shinichi

2015-08-01

This paper proposes a new disposable soft 3D force sensor that can be used to calculate either force or displacement and vibrations. It uses three Hall Effect sensors orthogonally placed around a cylindrical beam made of silicon rubber. A niobium permanent magnet is inside the silicon. When a force is applied to the end of the cylinder, it is compressed and bent to the opposite side of the force displacing the magnet. This displacement causes change in the magnetic flux around the ratiomatric linear sensors (Hall Effect sensors). By analysing these changes, we calculate the force or displacement in three directions using a lookup table. This sensor can be used in minimal invasive surgery and haptic feedback applications. The cheap construction, bio-compatibility and ease of miniaturization are few advantages of this sensor. The sensor design, and its characterization are presented in this work.

West Africa’s Efforts to Build Regional Security: An Analysis of Past ECOWAS Interventions to Determine what is Needed to Increase its Peacekeeping Capabilities

DTIC Science & Technology

2010-06-11

to foster that development . Thus, in order for West Africa to be at peace and develop politically and economically, an effective security...throughout the Ivorian territory and worked alongside French forces. The UN was very effective and responsive to the developments in the Ivorian...issues that may divide them and negatively impact on the effectiveness of any regional force. Much ink has been spilled in recent years about the

Walking, running and the evolution of short toes in humans.

PubMed

Rolian, Campbell; Lieberman, Daniel E; Hamill, Joseph; Scott, John W; Werbel, William

2009-03-01

The phalangeal portion of the forefoot is extremely short relative to body mass in humans. This derived pedal proportion is thought to have evolved in the context of committed bipedalism, but the benefits of shorter toes for walking and/or running have not been tested previously. Here, we propose a biomechanical model of toe function in bipedal locomotion that suggests that shorter pedal phalanges improve locomotor performance by decreasing digital flexor force production and mechanical work, which might ultimately reduce the metabolic cost of flexor force production during bipedal locomotion. We tested this model using kinematic, force and plantar pressure data collected from a human sample representing normal variation in toe length (N=25). The effect of toe length on peak digital flexor forces, impulses and work outputs was evaluated during barefoot walking and running using partial correlations and multiple regression analysis, controlling for the effects of body mass, whole-foot and phalangeal contact times and toe-out angle. Our results suggest that there is no significant increase in digital flexor output associated with longer toes in walking. In running, however, multiple regression analyses based on the sample suggest that increasing average relative toe length by as little as 20% doubles peak digital flexor impulses and mechanical work, probably also increasing the metabolic cost of generating these forces. The increased mechanical cost associated with long toes in running suggests that modern human forefoot proportions might have been selected for in the context of the evolution of endurance running.

On the effect of gyroscopic forces on the instability of certain fluid-elastic systems. Part 1: Definitions

NASA Astrophysics Data System (ADS)

Kornecki, A.

1983-09-01

This study was motivated by work on the stability of nonconservative elastic systems and flutter of certain fluid-elastic systems. A literature review revealed that the concepts of conservative forces (and systems) and gyroscopic forces (and systems) need clarifications, and the definitions formulated by different authors for the forces and systems are sometimes conflicting. In this report, these controversies are thoroughly discussed and conservative and gyroscopic systems are redefined within the framework of the classical dynamics of a system of particles.

The effect of workstation and task variables on forces applied during simulated meat cutting.

PubMed

McGorry, Raymond W; Dempsey, Patrick G; O'Brien, Niall V

2004-12-01

The purpose of the study was to investigate factors related to force and postural exposure during a simulated meat cutting task. The hypothesis was that workstation, tool and task variables would affect the dependent kinetic variables of gripping force, cutting moment and the dependent kinematic variables of elbow elevation and wrist angular displacement in the flexion/extension and radial/ulnar deviation planes. To evaluate this hypothesis a 3 x 3 x 2 x 2 x 2 (surface orientation by surface height by blade angle by cut complexity by work pace) within-subject factorial design was conducted with 12 participants. The results indicated that the variables can act and interact to modify the kinematics and kinetics of a cutting task. Participants used greater grip force and cutting moment when working at a pace based on productivity. The interactions of the work surface height and orientation indicated that the use of an adjustable workstation could minimize wrist deviation from neutral and improve shoulder posture during cutting operations. Angling the knife blade also interacted with workstation variables to improve wrist and upper extremity posture, but this benefit must be weighed against the potential for small increases in force exposure.

Lorentz-like force emerging from kinematic interactions between electrons and nuclei in molecules: A quantum mechanical origin of symmetry breaking that can trigger molecular chirality.

PubMed

Takatsuka, Kazuo

2017-02-28

The Longuet-Higgins (Berry) phase arising from nonadiabatic dynamics and the Aharonov-Bohm phase associated with the dynamics of a charged particle in the electromagnetic vector potential are well known to be individually a manifestation of a class of the so-called geometrical phase. We herein discuss another similarity between the force working on a charged particle moving in a magnetic field, the Lorentz force, and a force working on nuclei while passing across a region where they have a strong quantum mechanical kinematic (nonadiabatic) coupling with electrons in a molecule. This kinematic force is indeed akin to the Lorentz force in that its magnitude is proportional to the velocity of the relevant nuclei and works in the direction perpendicular to its translational motion. Therefore this Lorentz-like nonadiabatic force is realized only in space of more or equal to three dimensions, thereby highlighting a truly multi-dimensional effect of nonadiabatic interaction. We investigate its physical significance qualitatively in the context of breaking of molecular spatial symmetry, which is not seen otherwise without this force. This particular symmetry breaking is demonstrated in application to a coplanar collision between a planar molecule and an atom sharing the same plane. We show that the atom is guided by this force to the direction out from the plane, resulting in a configuration that distinguishes one side of the mirror plane from the other. This can serve as a trigger for the dynamics towards molecular chirality.

Women Workers: Trends & Issues, 1993 Handbook.

ERIC Educational Resources Information Center

Women's Bureau (DOL), Washington, DC.

This handbook offers a comprehensive view of the labor force activity of women in the United States and describes a range of legal and socioeconomic developments that have had an effect upon women's participation and progress in the work force. Through numerous statistical charts and tables, the book depicts change and reactions to change in the…

Open-loop control of quasiperiodic thermoacoustic oscillations

NASA Astrophysics Data System (ADS)

Guan, Yu; Gupta, Vikrant; Kashinath, Karthik; Li, Larry K. B.

2017-11-01

The open-loop application of periodic acoustic forcing has been shown to be a potentially effective strategy for controlling periodic thermoacoustic oscillations, but its effectiveness on aperiodic thermoacoustic oscillations is less clear. In this experimental study, we apply periodic acoustic forcing to a ducted premixed flame oscillating quasiperiodically at two incommensurate natural frequencies, f1 and f2. We find that (i) above a critical forcing amplitude, the system locks into the forcing by oscillating only at the forcing frequency ff, producing a closed periodic orbit in phase space with no evidence of the original T2 torus attractor; (ii) the critical forcing amplitude required for lock-in decreases as ff approaches either f1 or f2, resulting in characteristic ∨-shaped lock-in boundaries around the two natural modes; and (iii) for a wide range of forcing frequencies, the system's oscillation amplitude can be reduced to less than 20% of that of the unforced system. These findings show that the open-loop application of periodic acoustic forcing can be an effective strategy for controlling aperiodic thermoacoustic oscillations. This work was supported by the Research Grants Council of Hong Kong (Project No. 16235716 and 26202815).

[Medical support of Russian Armed Forces: the results and perspectives].

PubMed

Shappo, V V

2008-01-01

The results of work of the Russian Federation Armed Forces medical service obtained in 2007 were summarized and the main problems of its activities in the current year and the very near future were determined. So the work at defining medical support as a type of Army and Navy support was began. The most important task of medical service in 2008 is realization of the Armed Forces medical support conception and goal-oriented program "The improvement of Russian Federation Armed Forces medical support in 2008-2012", the formation of two-level system of personnel's medical support. During the task realization the medical units and institutions are reorganized into federal state institutions. The RF DM Main Military Medical Headquarters works at significant improvement of war and military service veterans' medical attendance. The departmental program "Development of material and technical basis of military medical institutions for 2001-2010" is successfully realized. The measures to optimize the assignment of graduates from military medical higher schools are carried out. The tasks to improve the research work were outlined. The new principles of organization of military medical service control and work will be based on centralization of planning and decentralization of decision implementation, the possibility of military medical units to carry it out taking into account the common intention, safe feedback in order to make the work of army and navy medical specialists more effective in any conditions.

The New Work Force. Trends and Issues Alerts.

ERIC Educational Resources Information Center

Imel, Susan

During the last years of this century, the work force will grow more slowly, becoming older, more female, and more disadvantaged. An increasing number of minority groups and immigrants will enter the work force. Despite public demands for reform, education lags behind in preparing youth for employment. The changing work force has many implications…

Study of the Vibration Effect on the Cutting Forces and Roughness of Slub Milling

NASA Astrophysics Data System (ADS)

Germa, S.; Estrems Amestoy, M.; Sánchez Reinoso, H. T.; Franco Chumillas, P.

2009-11-01

For the planning process of slab milling operations, the vibration of the tool is the main factor to be considered. Under vibration conditions, the effect of the small displacements of the cutting tool and the cutting forces on the chip thickness must be minimized in order to avoid undesirable consequences, such as the fast flank wear, superficial defects and roughness increase. In this work, a mathematical model is developed to take into account the combined effect of the cutting tool and workpiece oscillation, as well as the axial errors of different milling tool tips. As a result, the model estimates the variation of the cutting forces and the ideal surface roughness.

Caretaking as articulation work: the effects of taking up responsibility for a child with asthma on labor force participation.

PubMed

Timmermans, Stefan; Freidin, Betina

2007-10-01

A well-established quantitative literature has documented the financial toll for women's caretaking. Still, we do not know much about the process by which women end up taking on an extensive caretaking role and what they do on a daily basis. Based on in-depth interviews with a convenience sample of fifty caretakers of school aged children with asthma and nine health professionals in the USA, this study examines how health professionals socialize mothers into an intensive caretaking role for their children with asthma, how mothers negotiated and perform that role, and the impact of care work on their labor force participation. Care providers assign broad caretaking tasks that require further articulation work to get the job done. Although mothers care for their children in varied ways, caring for a child with a chronic disease remains a time-consuming activity. Mothers pay a price for the indeterminate nature of articulation work by scaling back their involvement in the paid labor force.

Working Memory Effects in the L2 Processing of Ambiguous Relative Clauses

ERIC Educational Resources Information Center

Hopp, Holger

2014-01-01

This article investigates whether and how L2 sentence processing is affected by memory constraints that force serial parsing. Monitoring eye movements, we test effects of working memory on L2 relative-clause attachment preferences in a sample of 75 late-adult German learners of English and 25 native English controls. Mixed linear regression…

Teachers, School Choice and Competition: Lock-In Effects within and between Sectors

ERIC Educational Resources Information Center

Parding, Karolina; McGrath-Champ, Susan; Stacey, Meghan

2017-01-01

Neoliberal forces since the latter part of the 20th century have ushered in greater devolution in state schooling systems, producing uneven effects on the working conditions of teachers, commonly the largest segment of the public sector workforce. Within this context, this paper examines secondary teachers' working conditions as they relate to the…

United States Air Force Graduate Student Research Program for 1990. Program Management Report

DTIC Science & Technology

1992-06-05

were extensively studied using pencil lead breaks in a center notch. For the fatigue studies center crack samples of 2024 - T351 aluminum were used...Research Program (SFRP) provides opportunities for research in the physical sciences, engineering, and life sciences. The program has been effective ...positive effect on teaching. (WRDC/FDL) Several mentioned the opportunity for introduction to research interests of the Air Force and the opportunity to work

Safe Schools, Safe Communities.

ERIC Educational Resources Information Center

Lewis, Julie E.; Pickett, Dean; Pulliam, Janet L.; Schwartz, Richard A.; St. Germaine, Anne-Marie; Underwood, Julie; Worona, Jay

Schools must work together with agencies, groups, and individuals to eliminate the forces leading children to violence. Chapter 1, "School Safety: Working Together to Keep Schools Safe," stresses the importance of community collaboration in violence prevention. Effective prevention requires sharing information about students, consistent…

Quantum Field Energy Sensor based on the Casimir Effect

NASA Astrophysics Data System (ADS)

Ludwig, Thorsten

The Casimir effect converts vacuum fluctuations into a measurable force. Some new energy technologies aim to utilize these vacuum fluctuations in commonly used forms of energy like electricity or mechanical motion. In order to study these energy technologies it is helpful to have sensors for the energy density of vacuum fluctuations. In today's scientific instrumentation and scanning microscope technologies there are several common methods to measure sub-nano Newton forces. While the commercial atomic force microscopes (AFM) mostly work with silicon cantilevers, there are a large number of reports on the use of quartz tuning forks to get high-resolution force measurements or to create new force sensors. Both methods have certain advantages and disadvantages over the other. In this report the two methods are described and compared towards their usability for Casimir force measurements. Furthermore a design for a quantum field energy sensor based on the Casimir force measurement will be described. In addition some general considerations on extracting energy from vacuum fluctuations will be given.

Optical forces, torques, and force densities calculated at a microscopic level using a self-consistent hydrodynamics method

NASA Astrophysics Data System (ADS)

Ding, Kun; Chan, C. T.

2018-04-01

The calculation of optical force density distribution inside a material is challenging at the nanoscale, where quantum and nonlocal effects emerge and macroscopic parameters such as permittivity become ill-defined. We demonstrate that the microscopic optical force density of nanoplasmonic systems can be defined and calculated using the microscopic fields generated using a self-consistent hydrodynamics model that includes quantum, nonlocal, and retardation effects. We demonstrate this technique by calculating the microscopic optical force density distributions and the optical binding force induced by external light on nanoplasmonic dimers. This approach works even in the limit when the nanoparticles are close enough to each other so that electron tunneling occurs, a regime in which classical electromagnetic approach fails completely. We discover that an uneven distribution of optical force density can lead to a light-induced spinning torque acting on individual particles. The hydrodynamics method offers us an accurate and efficient approach to study optomechanical behavior for plasmonic systems at the nanoscale.

Propellers in yaw

NASA Technical Reports Server (NTRS)

Ribner, Herbert S

1945-01-01

It was realized as early as 1909 that a propeller in yaw develops a side force like that of a fin. In 1917, R. G. Harris expressed this force in terms of the torque coefficient for the unyawed propeller. Of several attempts to express the side force directly in terms of the shape of the blades, however, none has been completely satisfactory. An analysis that incorporates induction effects not adequately covered in previous work and that gives good agreement with experiment over a wide range of operating conditions is presented. The present analysis shows that the fin analogy may be extended to the form of the side-force expression and that the effective fin area may be taken as the projected side area of the propeller.

Labor-Force Participation, Policies & Practices in an Aging America: Adaptation Essential for a Healthy & Resilient Population.

PubMed

Berkman, Lisa F; Börsch-Supan, Axel; Avendano, Mauricio

2015-01-01

Population aging in the United States poses challenges to societal institutions while simultaneously creating opportunities to build a more resilient, successful, and cohesive society. Work organization and labor-force participation are central to both the opportunities and challenges posed by our aging society. We argue that expectations about old age have not sufficiently adapted to the reality of aging today. Our institutions need more adaptation in order to successfully face the consequences of demographic change. Although this adaptation needs to focus especially on work patterns among the "younger elderly," our society has to change its general attitudes toward work organization and labor-force participation, which will have implications for education and health care. We also show that work's beneficial effects on well-being in older ages are often neglected, while the idea that older workers displace younger workers is a misconception emerging from the "lump of labor" fallacy. We conclude, therefore, that working at older ages can lead to better quality of life for older people and to a more productive and resilient society overall.

Turbine blade tip and seal clearance excitation forces

NASA Technical Reports Server (NTRS)

Martinez-Sanchez, M.; Jaroux, B.

1992-01-01

Experimental and theoretical work done as Phase 3 of a program sponsored by MSFC to investigate the magnitude, origin, and parametric variations of destabilizing forces which arise in high power turbines due to blade-tip leakage effects are described. The two facilities which were built for this purpose are first described. The larger one is a closed, 2 atm pressurized Freon-12 flow loop in which is installed a 1:1 replica of the SSME first stage hydrogen turbine, which can be driven by the flow, and which generates about 14 KW of power into a load-absorbing DC generator. The smaller facility is used to measure the forces on labyrinth seals of the same type as those used in our turbine tests with a shrouded turbine. The seals can be kinematically whirled and spun (independently), and the inlet swirl can be set to a variety of values. Air is the working fluid (with atmospheric discharge) and the data are real-time pressure distributions in the seal glands. The five different unshrouded turbine configurations were tested with static offsets, plus one with a shroud band and a two-ridge seal. Theoretical models of various degrees of complexity were developed to help interpreting and extrapolating the data. The notion of partial work done by the fluid leaking through the tip gaps was put on a quantitative basis by examining the leakage vortex roll-up dynamics. This was used to obtain a theory of the work loss due to a uniform gap. Perturbation and multiple scale arguments were then used to extend this to the case of an eccentric turbine. This yields an unsteady, 3-D theory which can predict the distribution of the approach flow, and its effect on work defect, cross-forces, pressure patterns, and dynamic damping. The predictions agree qualitatively with the data and exhibit the correct trends, but the cross-forces are generally under-predicted.

Evidence for non-conservative current-induced forces in the breaking of Au and Pt atomic chains.

PubMed

Sabater, Carlos; Untiedt, Carlos; van Ruitenbeek, Jan M

2015-01-01

This experimental work aims at probing current-induced forces at the atomic scale. Specifically it addresses predictions in recent work regarding the appearance of run-away modes as a result of a combined effect of the non-conservative wind force and a 'Berry force'. The systems we consider here are atomic chains of Au and Pt atoms, for which we investigate the distribution of break down voltage values. We observe two distinct modes of breaking for Au atomic chains. The breaking at high voltage appears to behave as expected for regular break down by thermal excitation due to Joule heating. However, there is a low-voltage breaking mode that has characteristics expected for the mechanism of current-induced forces. Although a full comparison would require more detailed information on the individual atomic configurations, the systems we consider are very similar to those considered in recent model calculations and the comparison between experiment and theory is very encouraging for the interpretation we propose.

The force-dependent mechanism of DnaK-mediated mechanical folding

PubMed Central

Perales-Calvo, Judit; Giganti, David; Stirnemann, Guillaume; Garcia-Manyes, Sergi

2018-01-01

It is well established that chaperones modulate the protein folding free-energy landscape. However, the molecular determinants underlying chaperone-mediated mechanical folding remain largely elusive, primarily because the force-extended unfolded conformation fundamentally differs from that characterized in biochemistry experiments. We use single-molecule force-clamp spectroscopy, combined with molecular dynamics simulations, to study the effect that the Hsp70 system has on the mechanical folding of three mechanically stiff model proteins. Our results demonstrate that, when working independently, DnaJ (Hsp40) and DnaK (Hsp70) work as holdases, blocking refolding by binding to distinct substrate conformations. Whereas DnaK binds to molten globule–like forms, DnaJ recognizes a cryptic sequence in the extended state in an unanticipated force-dependent manner. By contrast, the synergetic coupling of the Hsp70 system exhibits a marked foldase behavior. Our results offer unprecedented molecular and kinetic insights into the mechanisms by which mechanical force finely regulates chaperone binding, directly affecting protein elasticity. PMID:29487911

Work and Family. Policies for a Changing Work Force.

ERIC Educational Resources Information Center

Ferber, Marianne A., Ed.; And Others

This book reviews changes in work and family structures and their effects on worker productivity and employer practices. The first two chapters introduce the topic and trace the history of family structure and composition in the United States, the changing nature of employment, and the central role of the employment relationship to the social…

The aging work force in Korea.

PubMed

Hong, Jungyeon; Lee, Kangsook

2012-04-01

Korea has the fastest aging population and least fertile population of all Organization Economic Cooperation and Development countries, and it is undertaking significant preparations for an aging society. So, we want to review the present status of Elderly workers' occupational disorders and preparations, which is performed by governmental, social parties. We examine the current status of Korea's aging work force, focusing on occupational disorders (injuries and diseases), and retirements, and the associated health effects. Despite the efforts and concern about Korea's aging society since the issue was first identified, Korea's limited experience in operating a national public pension system, and a mature social security system shows that the needs of Korea's aging society cannot be fully satisfied. This problem has already resulted in increasing labor employment rates and delays in retirement from the labor market. We suggest a policy for elderly workers considering various determinants that can lead to successful employment, retirement, and health promotion for the aging work force.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riley, H.W. Jr.

Over the years, utilities have been going through cost cutting measures and efficiency improvements in an effort to be more competitive or stay competitive within their market territory. The next logical step for a utility to take is to promote Creativity. With a creative environment in place, utilities can keep pace with the changes in the industry and maintain or attain their competitive advantage. The goal of the creative electric utility work-force is to keep up with changes in the industry and become more competitive as the market becomes more competitive. Utilities can change the way they do business bymore » utilizing an effectively trained and skilled work-force on the subject of creative thinking. Creativity within a work-force depends on the employees desire to understand difficult aspects of his or her life. This paper will provide the foundation for linking Creativity and the electric utility industry.« less

Electronic forces as descriptors of nucleophilic and electrophilic regioselectivity and stereoselectivity.

PubMed

Liu, Shubin; Rong, Chunying; Lu, Tian

2017-01-04

One of the main tasks of theoretical chemistry is to rationalize computational results with chemical insights. Key concepts of such nature include nucleophilicity, electrophilicity, regioselectivity, and stereoselectivity. While computational tools are available to predict barrier heights and other reactivity properties with acceptable accuracy, a conceptual framework to appreciate above quantities is still lacking. In this work, we introduce the electronic force as the fundamental driving force of chemical processes to understand and predict molecular reactivity. It has three components but only two are independent. These forces, electrostatic and steric, can be employed as reliable descriptors for nucleophilic and electrophilic regioselectivity and stereoselectivity. The advantages of using these forces to evaluate molecular reactivity are that electrophilic and nucleophilic attacks are featured by distinct characteristics in the electrostatic force and no knowledge of quantum effects included in the kinetic and exchange-correlation energies is required. Examples are provided to highlight the validity and general applicability of these reactivity descriptors. Possible applications in ambident reactivity, σ and π holes, frustrated Lewis pairs, and stereoselective reactions are also included in this work.

Effects of spine flexion and erector spinae maximal force on vertical squat jump height: a computational simulation study.

PubMed

Blache, Yoann; Monteil, Karine

2015-03-01

The purpose of this study was to evaluate the single and combined effects of initial spine flexion and maximal isometric force of the erector spinae on maximal vertical jump height during maximal squat jumping. Seven initial flexions of the 'thorax-head-arm' segment (between 20.1° and 71.6°) and five maximal isometric forces of the erector spinae (between 5600 and 8600 N) were tested. Thus, 35 squat jumps were simulated using a 2D simulation model of the musculoskeletal system. Vertical jump height varied at most about 0.094 and 0.021 m when the initial flexion of the 'thorax-head-arm' segment and the maximal force of the erector spinae were, respectively, maximal. These results were explained for the most part by the variation of total muscle work. The latter was mainly influenced by the work produced by the erector spinae which increased at most about 57 and 110 J when the initial flexion of the 'thorax-head-arm' segment and the maximal force of the erector spinae were, respectively, maximal. It was concluded that the increase in the initial flexion of the 'thorax-head-arm' segment and in the maximal isometric force of the erector spinae enables an increase in maximal vertical jump height during maximal squat jumping.

48 CFR 252.223-7004 - Drug-free work force.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 48 Federal Acquisition Regulations System 3 2013-10-01 2013-10-01 false Drug-free work force. 252... Provisions And Clauses 252.223-7004 Drug-free work force. As prescribed in 223.570-2, use the following clause: Drug-Free Work Force (SEP 1988) (a) Definitions. (1) Employee in a sensitive position, as used in...

48 CFR 252.223-7004 - Drug-free work force.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 48 Federal Acquisition Regulations System 3 2012-10-01 2012-10-01 false Drug-free work force. 252... Provisions And Clauses 252.223-7004 Drug-free work force. As prescribed in 223.570-2, use the following clause: Drug-Free Work Force (SEP 1988) (a) Definitions. (1) Employee in a sensitive position, as used in...

48 CFR 252.223-7004 - Drug-free work force.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 48 Federal Acquisition Regulations System 3 2011-10-01 2011-10-01 false Drug-free work force. 252... Provisions And Clauses 252.223-7004 Drug-free work force. As prescribed in 223.570-2, use the following clause: Drug-Free Work Force (SEP 1988) (a) Definitions. (1) Employee in a sensitive position, as used in...

48 CFR 252.223-7004 - Drug-free work force.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 48 Federal Acquisition Regulations System 3 2014-10-01 2014-10-01 false Drug-free work force. 252... Provisions And Clauses 252.223-7004 Drug-free work force. As prescribed in 223.570-2, use the following clause: Drug-Free Work Force (SEP 1988) (a) Definitions. (1) Employee in a sensitive position, as used in...

48 CFR 252.223-7004 - Drug-free work force.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Drug-free work force. 252... Provisions And Clauses 252.223-7004 Drug-free work force. As prescribed in 223.570-2, use the following clause: Drug-Free Work Force (SEP 1988) (a) Definitions. (1) Employee in a sensitive position, as used in...

40 CFR 35.936-14 - Force account work.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Force account work. 35.936-14 Section... Force account work. (a) A grantee must secure the project officer's prior written approval for use of the force account method for (1) any step 1 or step 2 work in excess of $10,000; (2) any sewer...

Occupational safety and HIV risk among female sex workers in China: A mixed-methods analysis of sex-work harms and mommies

PubMed Central

Yi, Huso; Zheng, Tiantian; Wan, Yanhai; Mantell, Joanne E.; Park, Minah; Csete, Joanne

2013-01-01

Female sex workers (FSWs) in China are exposed to multiple work-related harms that increase HIV vulnerability. Using mixed-methods, we explored the social-ecological aspects of sexual risk among 348 FSWs in Beijing. Sex-work harms were assessed by property stolen, being underpaid or not paid at all, verbal and sexual abuse, forced drinking; and forced sex more than once. The majority (90%) reported at least one type of harm, 38% received harm protection from ‘mommies’ (i.e., managers) and 32% reported unprotected sex with clients. In multivariate models, unprotected sex was significantly associated with longer involvement in sex work, greater exposure to harms, and no protection from mommies. Mommies’ protection moderated the effect of sex-work harms on unprotected sex with clients. Our ethnography indicated that mommies played a core role in sex-work networks. Such networks provide a basis for social capital; they are not only profitable economically, but also protect FSWs from sex-work harms. Effective HIV prevention interventions for FSWs in China must address the occupational safety and health of FSWs by facilitating social capital and protection agency (e.g., mommies) in the sex-work industry. PMID:22375698

Conference-EC-US Task Force Joint US-EU Workshop on Metabolomics and Environmental Biotechnology

DOE Office of Scientific and Technical Information (OSTI.GOV)

PI: Lily Y. Young

2009-06-04

Since 1990, the EC-US Task Force on Biotechnology Research has been coordinating transatlantic efforts to guide and exploit the ongoing revolution in biotechnology and the life sciences. The Task Force was established in June 1990 by the European Commission and the White House Office of Science and Technology Policy. The Task Force has acted as an effective forum for discussion, coordination, and development of new ideas for the last 18 years. Task Force members are European Commission and US Government science and technology administrators who meet annually to enhance communication across the Atlantic, and to encourage collaborative research. Through sponsoringmore » workshops, and other activities, the Task Force also brings together scientific leaders and early career researchers from both sides of the Atlantic to forecast research challenges and opportunities and to promote better links between researchers. Over the years, by keeping a focus on the future of science, the Task Force has played a key role in establishing a diverse range of emerging scientific fields, including biodiversity research, neuroinformatics, genomics, nanobiotechnology, neonatal immunology, transkingdom molecular biology, biologically-based fuels, and environmental biotechnology. The EC-US Task Force has sponsored a number of Working Groups on topics of mutual transatlantic interest. The idea to create a Working Group on Environmental Biotechnology research was discussed in the Task Force meeting of October 1993. The EC-US Working Group on Environmental Biotechnology set as its mission 'To train the next generation of leaders in environmental biotechnology in the United States and the European Union to work collaboratively across the Atlantic.' Since 1995, the Working Group supported three kinds of activities, all of which focus one early career scientists: (1) Workshops on the use of molecular methods and genomics in environmental biotechnology; (2) Short courses with theoretical, laboratory and field elements; and (3) Short term exchange fellowships. The short term exchange fellowships were created to enable young scientists to develop collaborations with colleagues across the Atlantic and to learn a new skill or expertise in the area of environmental biotechnology.« less

Analog and numerical experiments investigating force chain influences on bed conditions in granular flows

NASA Astrophysics Data System (ADS)

Estep, J.; Dufek, J.

2013-12-01

Granular flows are fundamental processes in several terrestrial and planetary natural events; including surficial flows on volcanic edifices, debris flows, landslides, dune formation, rock falls, sector collapses, and avalanches. Often granular flows can be two-phase, whereby interstitial fluids occupy void space within the particulates. The mobility of granular flows has received significant attention, however the physics that govern their internal behavior remain poorly understood. Here we extend upon previous research showing that force chains can transmit extreme localized forces to the substrates of free surface granular flows, and we combine experimental and computational approaches to further investigate the forces at the bed of simplified granular flows. Analog experiments resolve discrete bed forces via a photoelastic technique, while numerical experiments validate laboratory tests using discrete element model (DEM) simulations. The current work investigates (1) the role of distributed grain sizes on force transmission via force chains, and (2) how the inclusion of interstitial fluids effects force chain development. We also include 3D numerical simulations to apply observed 2D characteristics into real world perspective, and ascertain if the added dimension alters force chain behavior. Previous research showed that bed forces generated by force chain structures can transiently greatly exceed (by several 100%) the bed forces predicted from continuum approaches, and that natural materials are more prone to excessive bed forces than photoelastic materials due to their larger contact stiffnesses. This work suggests that force chain activity may play an important role in the bed physics of dense granular flows by influencing substrate entrainment. Photoelastic experiment image showing force chains in gravity driven granular flow.

The Effect of Varying Jaw-elevator Muscle Forces on a Finite Element Model of a Human Cranium.

PubMed

Toro-Ibacache, Viviana; O'Higgins, Paul

2016-07-01

Finite element analyses simulating masticatory system loading are increasingly undertaken in primates, hominin fossils and modern humans. Simplifications of models and loadcases are often required given the limits of data and technology. One such area of uncertainty concerns the forces applied to cranial models and their sensitivity to variations in these forces. We assessed the effect of varying force magnitudes among jaw-elevator muscles applied to a finite element model of a human cranium. The model was loaded to simulate incisor and molar bites using different combinations of muscle forces. Symmetric, asymmetric, homogeneous, and heterogeneous muscle activations were simulated by scaling maximal forces. The effects were compared with respect to strain distribution (i.e., modes of deformation) and magnitudes; bite forces and temporomandibular joint (TMJ) reaction forces. Predicted modes of deformation, strain magnitudes and bite forces were directly proportional to total applied muscle force and relatively insensitive to the degree of heterogeneity of muscle activation. However, TMJ reaction forces and mandibular fossa strains decrease and increase on the balancing and working sides according to the degree of asymmetry of loading. These results indicate that when modes, rather than magnitudes, of facial deformation are of interest, errors in applied muscle forces have limited effects. However the degree of asymmetric loading does impact on TMJ reaction forces and mandibular fossa strains. These findings are of particular interest in relation to studies of skeletal and fossil material, where muscle data are not available and estimation of muscle forces from skeletal proxies is prone to error. Anat Rec, 299:828-839, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

The effect of the serum corona on interactions between a single nano-object and a living cell

NASA Astrophysics Data System (ADS)

Dror, Yael; Sorkin, Raya; Brand, Guy; Boubriak, Olga; Urban, Jill; Klein, Jacob

2017-04-01

Nanoparticles (NPs) which enter physiological fluids are rapidly coated by proteins, forming a so-called corona which may strongly modify their interaction with tissues and cells relative to the bare NPs. In this work the interactions between a living cell and a nano-object, and in particular the effect on this of the adsorption of serum proteins, are directly examined by measuring the forces arising as an Atomic Force Microscope tip (diameter 20 nm) - simulating a nano-object - approaches and contacts a cell. We find that the presence of a serum protein corona on the tip strongly modifies the interaction as indicated by pronounced increase in the indentation, hysteresis and work of adhesion compared to a bare tip. Classically one expects an AFM tip interacting with a cell surface to be repelled due to cell elastic distortion, offset by tip-cell adhesion, and indeed such a model fits the bare-tip/cell interaction, in agreement with earlier work. However, the force plots obtained with serum-modified tips are very different, indicating that the cell is much more compliant to the approaching tip. The insights obtained in this work may promote better design of NPs for drug delivery and other nano-medical applications.

The effect of the serum corona on interactions between a single nano-object and a living cell

PubMed Central

Dror, Yael; Sorkin, Raya; Brand, Guy; Boubriak, Olga; Urban, Jill; Klein, Jacob

2017-01-01

Nanoparticles (NPs) which enter physiological fluids are rapidly coated by proteins, forming a so-called corona which may strongly modify their interaction with tissues and cells relative to the bare NPs. In this work the interactions between a living cell and a nano-object, and in particular the effect on this of the adsorption of serum proteins, are directly examined by measuring the forces arising as an Atomic Force Microscope tip (diameter 20 nm) - simulating a nano-object - approaches and contacts a cell. We find that the presence of a serum protein corona on the tip strongly modifies the interaction as indicated by pronounced increase in the indentation, hysteresis and work of adhesion compared to a bare tip. Classically one expects an AFM tip interacting with a cell surface to be repelled due to cell elastic distortion, offset by tip-cell adhesion, and indeed such a model fits the bare-tip/cell interaction, in agreement with earlier work. However, the force plots obtained with serum-modified tips are very different, indicating that the cell is much more compliant to the approaching tip. The insights obtained in this work may promote better design of NPs for drug delivery and other nano-medical applications. PMID:28383528

An investigation into electromagnetic force models: differences in global and local effects demonstrated by selected problems

NASA Astrophysics Data System (ADS)

Reich, Felix A.; Rickert, Wilhelm; Müller, Wolfgang H.

2018-03-01

This study investigates the implications of various electromagnetic force models in macroscopic situations. There is an ongoing academic discussion which model is "correct," i.e., generally applicable. Often, gedankenexperiments with light waves or photons are used in order to motivate certain models. In this work, three problems with bodies at the macroscopic scale are used for computing theoretical model-dependent predictions. Two aspects are considered, total forces between bodies and local deformations. By comparing with experimental data, insight is gained regarding the applicability of the models. First, the total force between two cylindrical magnets is computed. Then a spherical magnetostriction problem is considered to show different deformation predictions. As a third example focusing on local deformations, a droplet of silicone oil in castor oil is considered, placed in a homogeneous electric field. By using experimental data, some conclusions are drawn and further work is motivated.

Influence of psoriasis on work.

PubMed

Mattila, Kalle; Leino, Mauri; Mustonen, Anssi; Koulu, Leena; Tuominen, Risto

2013-04-01

Previous research indicates that psoriasis has an impact on early retirement, sick leave days and reduced work performance. To evaluate the disadvantages at work caused by psoriasis. The sample was based on patients visiting the dermatology outpatient clinic in Turku University Hospital. 262 returned a mailed questionnaire. The subjects were asked how many hours they were on a sick leave (absenteeism) and working while sick (presenteeism) due to psoriasis and other health reasons. Of the retired, 17.0% felt they were retired due to psoriasis. Those in the active work force reported on average 4.5 hours absenteeism and 8.3 hours of presenteeism due to psoriasis during the last 4 weeks. Psoriasis caused 27.0% of the total absenteeism and 39.0% of presenteeism. More than a quarter (28.9%) had been forced to modify their work due to psoriasis, most frequently to make the work less irritating for the skin. Psoriasis has a negative effect on patients' work in many ways, causing early retirement from work, sick leave days, change of occupation and work modifications.

Work experience and gender differences in chronic disease risk in older Mexicans.

PubMed

Salinas, Jennifer J; Peek, M Kristen

2008-08-01

The purpose of this study is to examine the relationship between labor force participation and gender differences in the prevalence of arthritis, diabetes, and hypertension. The Mexican Health and Aging Survey (MHAS) data is nationally representative sample of older Mexicans 50 years and older. Binomial logistic regression models were performed to examine differences between older Mexican men and women in the prevalence of arthritis, diabetes, and hypertension. Interaction effects were also estimated between gender and occupation, length of time in the labor force, and pension eligibility. Older Mexican women have a significantly greater risk of having arthritis, diabetes, and hypertension. Findings from this study suggest that within the same occupational classification, women suffer from the damaging effects on health to a greater extent than men. Interaction effects show that women who work in services or in client's home are particularly susceptible to arthritis. Moreover, women who work in sales were at a significantly greater risk of hypertension than men. Older Mexican women are at greater risk of chronic disease and part of their vulnerability is a result of the type of work that they do.

Masked Symptoms: Mid-Life Women, Health, and Work

ERIC Educational Resources Information Center

Abramson, Zelda

2007-01-01

Data from the Canadian Labour Force Survey (1997) reveal that relatively few mid-life women offer ill health as a reason for leaving their job or downshifting to part-time employment, implying that the role of ill health may be inconsequential in effecting changing patterns in mid-life women's labour force activity. In contrast, interviews with 30…

The Effects of Varying Schedules of Incentive Delivery on Technical Training.

ERIC Educational Resources Information Center

Pritchard, Robert D.; And Others

The research reported here was initiated and designed to assess the impact of various schedules of incentive delivery (schedules of reinforcement) on performance and attitudes in an Air Force-related setting. Civilian subjects matching the characteristics of Air Force trainees were hired to work for four weeks, one week under each of four…

Work Force Information and Career-Technical Education. In Brief: Fast Facts for Policy and Practice No. 10.

ERIC Educational Resources Information Center

Sommers, Dixie

To prepare young people and adults for labor market success, career-technical education (CTE) practitioners must know how to find and use work force information. Recent federal legislation, including the Workforce Investment Act of 1998, underscores the importance of work force education. The nationwide work force information system makes data on…

Finding the Effective Mass and Spring Constant of a Force Probe from Simple Harmonic Motion

NASA Astrophysics Data System (ADS)

Greene, Nathaniel R.; Gill, Tom; Eyerly, Stephen

2016-03-01

Force probes are versatile tools in the physics lab, but their internal workings can introduce artifacts when measuring rapidly changing forces. The Dual-Range Force Sensor by Vernier (Fig. 1) uses strain gage technology to measure force, based on the bending of a beam. Strain gages along the length of the beam change resistance as the beam bends (Fig. 2). The elasticity of the beam leads to oscillations that persist after being excited by an impulsive force. How quickly the force probe freely returns to zero is thus related to the rigidity of the beam and the total mass attached to it. By varying the added mass and measuring the resulting frequency of the probe's internal free oscillations, the effective mass and spring constant of the probe's moveable parts can be found. Weighing of the probe parts and conducting a Hooke's law experiment provide static verification of these parameters. Study of the force sensor's behavior helps students to learn about damped harmonic motion, mathematical modeling, and the limitations of measuring devices.

Target: Alcohol Abuse in the Hard-to-Reach Work Force. Ideas and Resources for Responding to Problems of the Hard-to-Reach Work Force.

ERIC Educational Resources Information Center

Informatics, Inc., Rockville, MD.

This guide is designed as a source of ideas and information for individuals and organizations interested in occupational alcoholism programs for the hard-to-reach work force. Following a brief overview of the problem and a report on progress in occupational alcoholism programming, a working definition of the hard-to-reach work force is offered;…

Uniformed Diplomacy: Reviewing the Army Leader Development Strategy in Light of the Regional Alignment of Forces Construct

DTIC Science & Technology

2014-06-13

Component Command. Developing this operational flexibility, Army Chief of Staff General Raymond Odierno believes, will help improve the effectiveness of...days of arriving in Africa, he and 45 other soldiers found themselves “working with local forces and U.S. Embassy staff to stiffen protection at the...missions, neither USARAF nor DOS have fully developed measure of effectiveness criteria for these deployments.35 Thus far each mission’s after action

Finite Element Simulations of Micro Turning of Ti-6Al-4V using PCD and Coated Carbide tools

NASA Astrophysics Data System (ADS)

Jagadesh, Thangavel; Samuel, G. L.

2017-02-01

The demand for manufacturing axi-symmetric Ti-6Al-4V implants is increasing in biomedical applications and it involves micro turning process. To understand the micro turning process, in this work, a 3D finite element model has been developed for predicting the tool chip interface temperature, cutting, thrust and axial forces. Strain gradient effect has been included in the Johnson-Cook material model to represent the flow stress of the work material. To verify the simulation results, experiments have been conducted at four different feed rates and at three different cutting speeds. Since titanium alloy has low Young's modulus, spring back effect is predominant for higher edge radius coated carbide tool which leads to the increase in the forces. Whereas, polycrystalline diamond (PCD) tool has smaller edge radius that leads to lesser forces and decrease in tool chip interface temperature due to high thermal conductivity. Tool chip interface temperature increases by increasing the cutting speed, however the increase is less for PCD tool as compared to the coated carbide tool. When uncut chip thickness decreases, there is an increase in specific cutting energy due to material strengthening effects. Surface roughness is higher for coated carbide tool due to ploughing effect when compared with PCD tool. The average prediction error of finite element model for cutting and thrust forces are 11.45 and 14.87 % respectively.

Energetic costs of producing muscle work and force in a cyclical human bouncing task

PubMed Central

Kuo, Arthur D.

2011-01-01

Muscles expend energy to perform active work during locomotion, but they may also expend significant energy to produce force, for example when tendons perform much of the work passively. The relative contributions of work and force to overall energy expenditure are unknown. We therefore measured the mechanics and energetics of a cyclical bouncing task, designed to control for work and force. We hypothesized that near bouncing resonance, little work would be performed actively by muscle, but the cyclical production of force would cost substantial metabolic energy. Human subjects (n = 9) bounced vertically about the ankles at inversely proportional frequencies (1–4 Hz) and amplitudes (15–4 mm), such that the overall rate of work performed on the body remained approximately constant (0.30 ± 0.06 W/kg), but the forces varied considerably. We used parameter identification to estimate series elasticity of the triceps surae tendon, as well as the work performed actively by muscle and passively by tendon. Net metabolic energy expenditure for bouncing at 1 Hz was 1.15 ± 0.31 W/kg, attributable mainly to active muscle work with an efficiency of 24 ± 3%. But at 3 Hz (near resonance), most of the work was performed passively, so that active muscle work could account for only 40% of the net metabolic rate of 0.76 ± 0.28 W/kg. Near resonance, a cost for cyclical force that increased with both amplitude and frequency of force accounted for at least as much of the total energy expenditure as a cost for work. Series elasticity reduces the need for active work, but energy must still be expended for force production. PMID:21212245

Estimation of the radial force using a disturbance force observer for a magnetically levitated centrifugal blood pump.

PubMed

Pai, C N; Shinshi, T; Shimokohbe, A

2010-01-01

Evaluation of the hydraulic forces in a magnetically levitated (maglev) centrifugal blood pump is important from the point of view of the magnetic bearing design. Direct measurement is difficult due to the absence of a rotor shaft, and computational fluid dynamic analysis demands considerable computational resource and time. To solve this problem, disturbance force observers were developed, using the radial controlled magnetic bearing of a centrifugal blood pump, to estimate the radial forces on the maglev impeller. In order to design the disturbance observer, the radial dynamic characteristics of a maglev impeller were evaluated under different working conditions. It was observed that the working fluid affects the additional mass and damping, while the rotational speed affects the damping and stiffness of the maglev system. Based on these results, disturbance force observers were designed and implemented. The designed disturbance force observers present a bandwidth of 45 Hz. In non-pulsatile conditions, the magnitude of the estimated radial thrust increases in proportion to the flowrate, and the rotational speed has little effect on the force direction. At 5 l/min against 100 mmHg, the estimated radial thrust is 0.95 N. In pulsatile conditions, this method was capable of estimating the pulsatile radial thrust with good response.

Evaluation and validation of musculoskeletal force feasible set indices: Application to manual wheelchair propulsion.

PubMed

Hernandez, Vincent; Gorce, Philippe; Rezzoug, Nasser

2018-02-08

The aim of this work was to assess handrim wheelchair propulsion effectiveness, related to the applied forces on the handrim, through the force feasible set. For a given posture of the upper-limb, it represents the set of isometric forces that can be applied on the handrim in any direction. The force feasible set was predicted from a musculoskeletal model of the upper-limb and trunk (10 degrees of freedom and 56 muscles). The aim of the first part of the study was to compare the force feasible set prediction and the force currently applied on the handrim. The second part proposes the creation of a new index called "Musculoskeletal Postural Performance Index" (MPPI) derived from the force feasible set and its comparison with the Mechanical Efficiency Force (MEF). These comparisons were conducted at 60, 80, 100, 120 and 140% of the Freely Chosen Frequency at submaximal and maximal conditions on 5 different phases of the push phase. The values of the MPPI were significantly correlated with those of the MEF. During the course of the push phase, the orientation of the force feasible set main axis approached that of the measured force and the force effectiveness evaluated through the MPPI increased. Copyright © 2017 Elsevier Ltd. All rights reserved.

Physical and psychosocial work environment factors and their association with health outcomes in Danish ambulance personnel – a cross-sectional study

PubMed Central

2012-01-01

Background Reviews of the literature on the health and work environment of ambulance personnel have indicated an increased risk of work-related health problems in this occupation. The aim of this study was to compare health status and exposure to different work environmental factors among ambulance personnel and the core work force in Denmark. In addition, to examine the association between physical and psychosocial work environment factors and different measures of health among ambulance personnel. Methods Data were taken from a nationwide sample of ambulance personnel and fire fighters (n = 1,691) and was compared to reference samples of the Danish work force. The questionnaire contained measures of physical and psychosocial work environment as well as measures of musculoskeletal pain, mental health, self-rated health and sleep quality. Results Ambulance personnel have half the prevalence of poor self-rated health compared to the core work force (5% vs. 10%). Levels of mental health were the same across the two samples whereas a substantially higher proportion of the ambulance personnel reported musculoskeletal pain (42% vs. 29%). The ambulance personnel had higher levels of emotional demands and meaningfulness of and commitment to work, and substantially lower levels of quantitative demands and influence at work. Only one out of ten aspects of physical work environment was consistently associated with higher levels of musculoskeletal pain. Emotional demands was the only psychosocial work factor that was associated with both poorer mental health and worse sleep quality. Conclusions Ambulance personnel have similar levels of mental health but substantially higher levels of musculoskeletal pain than the work force in general. They are more exposed to emotional demands and these demands are associated with higher levels of poor mental health and poor sleep quality. To improve work environment, attention should be paid to musculoskeletal problems and the presence of positive organizational support mechanisms that can prevent negative effects from the high levels of emotional demands. PMID:22824415

Effects of Geometrical and Flow Rates on the Prediction of Bottom Pressure Coefficients of Tunnel Lift Gate of Dams

NASA Astrophysics Data System (ADS)

Ameen, Sheeraz; Taher, Taha; Ahmed, Thamir M.

2018-06-01

Hydrostatics and hydrodynamics forces are generated and applied on the vertical lift tunnel gates due to the influence of a wide range of dam operating conditions. One of the most important forces is the uplift force resulting from the jet flow issuing below the gate. This force is based mainly upon many hydraulic and geometrical parameters. In this work, the uplift force is studied in terms of bottom pressure coefficient. The investigation is made paying particular attention on the effects of various three discharges and three gate lip angles on values of bottom pressure coefficients in addition to four different tunnel longitudinal slopes whose impact has not been studied in many previous works. Hydraulic model is constructed in this work for the sake of measuring all parameters required for estimating the bottom pressure coefficients, which are all examined against gate openings. The results show that the bottom pressure coefficient is related to the said variables, however, its behaviour and values are not necessary regular with variance of studied variables. The values are seen more significantly related to the flow rates and for some extent to the slopes of tunnel. An attempt by using the nonlinear regression of Statistical package of social sciences (SPSS) is made to set equations relating bottom pressure coefficient with gate openings for several angles of gate lips. The obtained equations are shown in good agreement with the selected cases of experimental results. The results are applicable for design purposes for similar geometrical and flow parameters considered in this study.

Establishing Criteria for Assigning Personnel to Air Force Jobs Requiring Heavy Work

DTIC Science & Technology

1978-07-01

loads (for example, carrying meat at the slaughterhouse , carrying of sacks, loading wood by hand) wood cutting in the forest by hand tools, agricultural...8217 factor history. Medical Service Digest (United States Air Force), 27(2), 1976, pp. 14-16. 186 Trimeloni, Col. B.D. The Role of Women in the Air Force...Rahden. Effect of training on maximum oxygen intake and on anaerobic metabolism in man. Int. Z. Angew Physiol., 24(2), 1967, pp. 102-110. 188 Wyndham, C.H

Case Study of the Application of the Weapon System Warranty on the C-130 Program.

DTIC Science & Technology

1986-09-01

31 Appendix A: Air Force Contract Law Center Suggested Systems Level Warranty Clauses . . . . . 33 Appendix B: Original C-130 Warranty ClauseCs...avoidance and still protect the government’s interest can work. vii This study recommends that the Department of Defense use the Air Force Contract Law Center’s...would have had the potential For allowing Lockheed to void a system level warranty had one been in effect such as the Air Force Contract Law Center’s

Dynamics and statics of nonaxisymmetric liquid bridges

NASA Technical Reports Server (NTRS)

Alexander, J. Iwan D.; Resnick, Andy; Zhang, Yiqiang; Fedoseyev, A.

1994-01-01

We finished the construction of the experimental apparatus and the design and testing of some of the visualization and data acquisition techniques. Experimental work focused on three areas: force measurements, loss of stability to nonaxisymmetric bridges, and vibration behavior. The experimental work is summarized in section 2. Selected results from our force measurement experiments are outlined in section 3. In addition we worked on the theory of the dynamic stability of axisymmetric bridges and undertook numerical simulation of the effects of inclined gravity vectors on the minimum volume stability limit for static bridges. The results and status of our theoretical work and numerical simulation are described in section 4. Papers published and in preparation, conference presentations, etc., are described in section 5. Work planned for the third year is discussed in section 6. References cited in the report are listed in section 7.

Optoelectrofluidic field separation based on light-intensity gradients

PubMed Central

Lee, Sanghyun; Park, Hyun Jin; Yoon, Jin Sung; Kang, Kwan Hyoung

2010-01-01

Optoelectrofluidic field separation (OEFS) of particles under light -intensity gradient (LIG) is reported, where the LIG illumination on the photoconductive layer converts the short-ranged dielectrophoresis (DEP) force to the long-ranged one. The long-ranged DEP force can compete with the hydrodynamic force by alternating current electro-osmosis (ACEO) over the entire illumination area for realizing effective field separation of particles. In the OEFS system, the codirectional illumination and observation induce the levitation effect, compensating the attenuation of the DEP force under LIG illumination by slightly floating particles from the surface. Results of the field separation and concentration of diverse particle pairs (0.82–16 μm) are well demonstrated, and conditions determining the critical radius and effective particle manipulation are discussed. The OEFS with codirectional LIG strategy could be a promising particle manipulation method in many applications where a rapid manipulation of biological cells and particles over the entire working area are of interest. PMID:20697461

Optoelectrofluidic field separation based on light-intensity gradients.

PubMed

Lee, Sanghyun; Park, Hyun Jin; Yoon, Jin Sung; Kang, Kwan Hyoung

2010-07-14

Optoelectrofluidic field separation (OEFS) of particles under light -intensity gradient (LIG) is reported, where the LIG illumination on the photoconductive layer converts the short-ranged dielectrophoresis (DEP) force to the long-ranged one. The long-ranged DEP force can compete with the hydrodynamic force by alternating current electro-osmosis (ACEO) over the entire illumination area for realizing effective field separation of particles. In the OEFS system, the codirectional illumination and observation induce the levitation effect, compensating the attenuation of the DEP force under LIG illumination by slightly floating particles from the surface. Results of the field separation and concentration of diverse particle pairs (0.82-16 mum) are well demonstrated, and conditions determining the critical radius and effective particle manipulation are discussed. The OEFS with codirectional LIG strategy could be a promising particle manipulation method in many applications where a rapid manipulation of biological cells and particles over the entire working area are of interest.

Reproducing Quantum Probability Distributions at the Speed of Classical Dynamics: A New Approach for Developing Force-Field Functors.

PubMed

Sundar, Vikram; Gelbwaser-Klimovsky, David; Aspuru-Guzik, Alán

2018-04-05

Modeling nuclear quantum effects is required for accurate molecular dynamics (MD) simulations of molecules. The community has paid special attention to water and other biomolecules that show hydrogen bonding. Standard methods of modeling nuclear quantum effects like Ring Polymer Molecular Dynamics (RPMD) are computationally costlier than running classical trajectories. A force-field functor (FFF) is an alternative method that computes an effective force field that replicates quantum properties of the original force field. In this work, we propose an efficient method of computing FFF using the Wigner-Kirkwood expansion. As a test case, we calculate a range of thermodynamic properties of Neon, obtaining the same level of accuracy as RPMD, but with the shorter runtime of classical simulations. By modifying existing MD programs, the proposed method could be used in the future to increase the efficiency and accuracy of MD simulations involving water and proteins.

Family, Work, and School Influences on the Decision to Enter the Military.

ERIC Educational Resources Information Center

Teachman, Jay D.; And Others

1993-01-01

Examined correlates of enlistment of young men in military. Focused on all volunteer force, paying attention to effects of work, school, and family roles on enlistment. Work and school enrollment significantly reduced likelihood of enlisting in military for whites but not for African Americans. Marriage and parenthood did not affect likelihood of…

Polymer translocation under a pulling force: Scaling arguments and threshold forces

NASA Astrophysics Data System (ADS)

Menais, Timothée

2018-02-01

DNA translocation through nanopores is one of the most promising strategies for next-generation sequencing technologies. Most experimental and numerical works have focused on polymer translocation biased by electrophoresis, where a pulling force acts on the polymer within the nanopore. An alternative strategy, however, is emerging, which uses optical or magnetic tweezers. In this case, the pulling force is exerted directly at one end of the polymer, which strongly modifies the translocation process. In this paper, we report numerical simulations of both linear and structured (mimicking DNA) polymer models, simple enough to allow for a statistical treatment of the pore structure effects on the translocation time probability distributions. Based on extremely extended computer simulation data, we (i) propose scaling arguments for an extension of the predicted translocation times τ ˜N2F-1 over the moderate forces range and (ii) analyze the effect of pore size and polymer structuration on translocation times τ .

Unbinding of targeted ultrasound contrast agent microbubbles by secondary acoustic forces.

PubMed

Garbin, Valeria; Overvelde, Marlies; Dollet, Benjamin; de Jong, Nico; Lohse, Detlef; Versluis, Michel

2011-10-07

Targeted molecular imaging with ultrasound contrast agent microbubbles is achieved by incorporating targeting ligands on the bubble coating and allows for specific imaging of tissues affected by diseases. Improved understanding of the interplay between the acoustic forces acting on the bubbles during insonation with ultrasound and other forces (e.g. shear due to blood flow, binding of targeting ligands to receptors on cell membranes) can help improve the efficacy of this technique. This work focuses on the effects of the secondary acoustic radiation force, which causes bubbles to attract each other and may affect the adhesion of targeted bubbles. First, we examine the translational dynamics of ultrasound contrast agent microbubbles in contact with (but not adherent to) a semi-rigid membrane due to the secondary acoustic radiation force. An equation of motion that effectively accounts for the proximity of the membrane is developed, and the predictions of the model are compared with experimental data extracted from optical recordings at 15 million frames per second. A time-averaged model is also proposed and validated. In the second part of the paper, initial results on the translation due to the secondary acoustic radiation force of targeted, adherent bubbles are presented. Adherent bubbles are also found to move due to secondary acoustic radiation force, and a restoring force is observed that brings them back to their initial positions. For increasing magnitude of the secondary acoustic radiation force, a threshold is reached above which the adhesion of targeted microbubbles is disrupted. This points to the fact that secondary acoustic radiation forces can cause adherent bubbles to detach and alter the spatial distribution of targeted contrast agents bound to tissues during activation with ultrasound. While the details of the rupture of intermolecular bonds remain elusive, this work motivates the use of the secondary acoustic radiation force to measure the strength of adhesion of targeted microbubbles.

Determination of thermodynamics and kinetics of RNA reactions by force

PubMed Central

Tinoco, Ignacio; Li, Pan T. X.; Bustamante, Carlos

2008-01-01

Single-molecule methods have made it possible to apply force to an individual RNA molecule. Two beads are attached to the RNA; one is on a micropipette, the other is in a laser trap. The force on the RNA and the distance between the beads are measured. Force can change the equilibrium and the rate of any reaction in which the product has a different extension from the reactant. This review describes use of laser tweezers to measure thermodynamics and kinetics of unfolding/refolding RNA. For a reversible reaction the work directly provides the free energy; for irreversible reactions the free energy is obtained from the distribution of work values. The rate constants for the folding and unfolding reactions can be measured by several methods. The effect of pulling rate on the distribution of force-unfolding values leads to rate constants for unfolding. Hopping of the RNA between folded and unfolded states at constant force provides both unfolding and folding rates. Force-jumps and force-drops, similar to the temperature jump method, provide direct measurement of reaction rates over a wide range of forces. The advantages of applying force and using single-molecule methods are discussed. These methods, for example, allow reactions to be studied in non-denaturing solvents at physiological temperatures; they also simplify analysis of kinetic mechanisms because only one intermediate at a time is present. Unfolding of RNA in biological cells by helicases, or ribosomes, has similarities to unfolding by force. PMID:17040613

In Vivo Force Decay of Niti Closed Coil Springs

PubMed Central

Cox, Crystal; Nguyen, Tung; Koroluk, Lorne; Ko, Ching-Chang

2014-01-01

Introduction Nickel-titanium (NiTi) closed coil springs are purported to deliver constant forces over extended ranges of activation and working times. In vivo studies supporting this claim are limited. The objective of this study is to evaluate changes in force decay properties of NiTi closed coil springs after clinical use. Methods Pseudoelastic force-deflection curves for 30 NiTi coil springs (used intra-orally) and 15 matched laboratory control springs (simulated intra-oral conditions - artificial saliva, 37°C) were tested pre- and post-retrieval via Dynamic Mechanical Analysis (DMA) and the Instron machine, respectively, to evaluate amount of force loss and hysteresis change following 4, 8, or 12 weeks of working time (n=10 per group). Effect of the oral environment and clinical use on force properties were evaluated by comparing in vivo and in vitro data. Results The springs studied showed a statistically significant decrease in force (~12%) following 4 weeks of clinical use (p<0.01), with a further significant decrease (~7%) from 4–8 weeks (p=0.03) and force levels appearing to remain steady thereafter. Clinical space closure at an average rate of 0.91mm per month was still observed despite this decrease in force. In vivo and in vitro force loss data were not statistically different. Conclusions NiTi closed coil springs do not deliver constant forces when used intra-orally, but they still allow for space closure rates of ~1mm/month. PMID:24703289

Acoustic radiation force on a heated sphere including effects of heat transfer and acoustic streaming

NASA Technical Reports Server (NTRS)

Lee, Chun P.; Wang, Taylor G.

1988-01-01

A previous theoretical result on the subject of the acoustic radiation force on a heated sphere (Lee and Wang, 1984) is reexamined. For a more complete understanding, effects of heat transfer and acoustic streaming are taken into consideration. Essentially, it was found that, at high sound-pressure levels in a steady situation, the force is not affected significantly by the temperature profile, consistent with the result of an experimental work (Leung and Wang, 1985). This resolves the earlier apparent contradiction between the theory and the experiment. If excessive hot air is accumulated around the sphere, which can happen in transient situations, the force can be weakened or reversed in sign. A heat transfer model due to acoustic streaming was also found.

Mechanical force antagonizes the inhibitory effects of RecX on RecA filament formation in Mycobacterium tuberculosis

PubMed Central

Le, Shimin; Chen, Hu; Zhang, Xinghua; Chen, Jin; Patil, K. Neelakanteshwar; Muniyappa, Kalappa; Yan, Jie

2014-01-01

Efficient bacterial recombinational DNA repair involves rapid cycles of RecA filament assembly and disassembly. The RecX protein plays a crucial inhibitory role in RecA filament formation and stability. As the broken ends of DNA are tethered during homologous search, RecA filaments assembled at the ends are likely subject to force. In this work, we investigated the interplay between RecX and force on RecA filament formation and stability. Using magnetic tweezers, at single molecular level, we found that Mycobacterium tuberculosis (Mt) RecX could catalyze stepwise de-polymerization of preformed MtRecA filament in the presence of ATP hydrolysis at low forces (<7 pN). However, applying larger forces antagonized the inhibitory effects of MtRecX, and a partially de-polymerized MtRecA filament could re-polymerize in the presence of MtRecX, which cannot be explained by previous models. Theoretical analysis of force-dependent conformational free energies of naked ssDNA and RecA nucleoprotein filament suggests that mechanical force stabilizes RecA filament, which provides a possible mechanism for the observation. As the antagonizing effect of force on the inhibitory function of RecX takes place in a physiological range; these findings broadly suggest a potential mechanosensitive regulation during homologous recombination. PMID:25294832

The effect of spatial discretization upon traveling wave body forcing of a turbulent wall-bounded flow

NASA Astrophysics Data System (ADS)

You, Soyoung; Goldstein, David

2015-11-01

DNS is employed to simulate turbulent channel flow subject to a traveling wave body force field near the wall. The regions in which forces are applied are made progressively more discrete in a sequence of simulations to explore the boundaries between the effects of discrete flow actuators and spatially continuum actuation. The continuum body force field is designed to correspond to the ``optimal'' resolvent mode of McKeon and Sharma (2010), which has the L2 norm of σ1. That is, the normalized harmonic forcing that gives the largest disturbance energy is the first singular mode with the gain of σ1. 2D and 3D resolvent modes are examined at a modest Reτ of 180. For code validation, nominal flow simulations without discretized forcing are compared to previous work by Sharma and Goldstein (2014) in which we find that as we increase the forcing amplitude there is a decrease in the mean velocity and an increase in turbulent kinetic energy. The same force field is then sampled into isolated sub-domains to emulate the effect of discrete physical actuators. Several cases will be presented to explore the dependencies between the level of discretization and the turbulent flow behavior.

Effect of fuel concentration and force on collective transport by a team of dynein motors

PubMed Central

Takshak, Anjneya; Roy, Tanushree; Tandaiya, Parag

2016-01-01

Abstract Motor proteins are essential components of intracellular transport inside eukaryotic cells. These protein molecules use chemical energy obtained from hydrolysis of ATP to produce mechanical forces required for transporting cargos inside cells, from one location to another, in a directed manner. Of these motors, cytoplasmic dynein is structurally more complex than other motor proteins involved in intracellular transport, as it shows force and fuel (ATP) concentration dependent step‐size. Cytoplasmic dynein motors are known to work in a team during cargo transport and force generation. Here, we use a complete Monte‐Carlo model of single dynein constrained by in vitro experiments, which includes the effect of both force and ATP on stepping as well as detachment of motors under force. We then use our complete Monte‐Carlo model of single dynein motor to understand collective cargo transport by a team of dynein motors, such as dependence of cargo travel distance and velocity on applied force and fuel concentration. In our model, cargos pulled by a team of dynein motors do not detach rapidly under higher forces, confirming the experimental observation of longer persistence time of dynein team on microtubule under higher forces. PMID:27727483

3 CFR - White House Task Force on Middle-Class Working Families

Code of Federal Regulations, 2010 CFR

2010-01-01

... 3 The President 1 2010-01-01 2010-01-01 false White House Task Force on Middle-Class Working... Task Force on Middle-Class Working Families Memorandum for the Heads of Executive Departments and... times. To these ends, I hereby direct the following: Section 1. White House Task Force on Middle-Class...

Prediction of Bubble Diameter at Detachment from a Wall Orifice in Liquid Cross Flow Under Reduced and Normal Gravity Conditions

NASA Technical Reports Server (NTRS)

Nahra, Henry K.; Kamotani, Y.

2003-01-01

Bubble formation and detachment is an integral part of the two-phase flow science. The objective of the present work is to theoretically investigate the effects of liquid cross-flow velocity, gas flow rate embodied in the momentum flux force, and orifice diameter on bubble formation in a wall-bubble injection configuration. A two-dimensional one-stage theoretical model based on a global force balance on the bubble evolving from a wall orifice in a cross liquid flow is presented in this work. In this model, relevant forces acting on the evolving bubble are expressed in terms of the bubble center of mass coordinates and solved simultaneously. Relevant forces in low gravity included the momentum flux, shear-lift, surface tension, drag and inertia forces. Under normal gravity conditions, the buoyancy force, which is dominant under such conditions, can be added to the force balance. Two detachment criteria were applicable depending on the gas to liquid momentum force ratio. For low ratios, the time when the bubble acceleration in the direction of the detachment angle is greater or equal to zero is calculated from the bubble x and y coordinates. This time is taken as the time at which all the detaching forces that are acting on the bubble are greater or equal to the attaching forces. For high gas to liquid momentum force ratios, the time at which the y coordinate less the bubble radius equals zero is calculated. The bubble diameter is evaluated at this time as the diameter at detachment from the fact that the bubble volume is simply given by the product of the gas flow rate and time elapsed. Comparison of the model s predictions was also made with predictions from a two-dimensional normal gravity model based on Kumar-Kuloor formulation and such a comparison is presented in this work.

Finite element analysis of deep wide-flanged pre-stressed girders to understand and control end cracking : [work plan].

DOT National Transportation Integrated Search

2011-01-01

Project -- Work Approach: The first phase will examine the critical problem of controlling cracking in the 82W : girders. This complex problem is controlled by effects of concentrated stresses, force : transfer from pre-tensioning strand, inelastic b...

Children and adults minimise activated muscle volume by selecting gait parameters that balance gross mechanical power and work demands.

PubMed

Hubel, Tatjana Y; Usherwood, James R

2015-09-01

Terrestrial locomotion on legs is energetically expensive. Compared with cycling, or with locomotion in swimming or flying animals, walking and running are highly uneconomical. Legged gaits that minimise mechanical work have previously been identified and broadly match walking and running at appropriate speeds. Furthermore, the 'cost of muscle force' approaches are effective in relating locomotion kinetics to metabolic cost. However, few accounts have been made for why animals deviate from either work-minimising or muscle-force-minimising strategies. Also, there is no current mechanistic account for the scaling of locomotion kinetics with animal size and speed. Here, we report measurements of ground reaction forces in walking children and adult humans, and their stance durations during running. We find that many aspects of gait kinetics and kinematics scale with speed and size in a manner that is consistent with minimising muscle activation required for the more demanding between mechanical work and power: spreading the duration of muscle action reduces activation requirements for power, at the cost of greater work demands. Mechanical work is relatively more demanding for larger bipeds--adult humans--accounting for their symmetrical M-shaped vertical force traces in walking, and relatively brief stance durations in running compared with smaller bipeds--children. The gaits of small children, and the greater deviation of their mechanics from work-minimising strategies, may be understood as appropriate for their scale, not merely as immature, incompletely developed and energetically sub-optimal versions of adult gaits. © 2015. Published by The Company of Biologists Ltd.

Report of the Council for Exceptional Children's Task Force on Policy Issues Relating to the Management of Students with Communicable Diseases.

ERIC Educational Resources Information Center

Council for Exceptional Children, Reston, VA.

How schools can effectively work with exceptional students who have communicable diseases was the focus of an eight-member Task Force appointed by the Council for Exceptional Children (CEC) Governmental Relations Committee. Its report begins with an overview of existing guidelines and defines specific communicable diseases (Hepatitis B,…

Health sector employment growth calls for improvements in labor productivity.

PubMed

Hofmarcher, Maria M; Festl, Eva; Bishop-Tarver, Leslie

2016-08-01

While rising costs of healthcare have put increased fiscal pressure on public finance, job growth in the health sector has had a stabilizing force on overall employment levels - not least in times of economic crises. In 2014 EU-15 countries employed 21 million people in the health and social care sector. Between 2000 and 2014 the share of employed persons in this sector rose from 9.5% to 12.5% of the total labor force in EU-15 countries. Over time labor input growth has shifted towards residential care activities and social work while labor in human health activities including hospitals and ambulatory care still comprises the major share. About half of the human health labor force works in hospital. Variation of health and social care employment is large even in countries with generally comparable institutional structures. While standard measures of productivity in health and social care are not yet comparable across countries, we argue that labor productivity of a growing health work force needs more attention. The long-term stability of the health system will require care delivery models that better utilize a growing health work force in concert with smart investments in digital infrastructure to support this transition. In light of this, more research is needed to explain variations in health and social care labor endowments, to identify effective policy measures of labor productivity enhancement including enhanced efforts to develop comparable productivity indicators in these areas. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Optical tweezers reveal force plateau and internal friction in PEG-induced DNA condensation.

PubMed

Ojala, Heikki; Ziedaite, Gabija; Wallin, Anders E; Bamford, Dennis H; Hæggström, Edward

2014-03-01

The simplified artificial environments in which highly complex biological systems are studied do not represent the crowded, dense, salty, and dynamic environment inside the living cell. Consequently, it is important to investigate the effect of crowding agents on DNA. We used a dual-trap optical tweezers instrument to perform force spectroscopy experiments at pull speeds ranging from 0.3 to 270 μm/s on single dsDNA molecules in the presence of poly(ethylene glycol) (PEG) and monovalent salt. PEG of sizes 1,500 and 4,000 Da condensed DNA, and force-extension data contained a force plateau at approximately 1 pN. The level of the force plateau increased with increasing pull speed. During slow pulling the dissipated work increased linearly with pull speed. The calculated friction coefficient did not depend on amount of DNA incorporated in the condensate, indicating internal friction is independent of the condensate size. PEG300 had no effect on the dsDNA force-extension curve. The force plateau implies that condensation induced by crowding agents resembles condensation induced by multivalent cations.

Labor-Force Participation, Policies & Practices in an Aging America: Adaptation Essential for a Healthy & Resilient Population

PubMed Central

Berkman, Lisa F.; Börsch-Supan, Axel; Avendano, Mauricio

2016-01-01

Population aging in the United States poses challenges to societal institutions while simultaneously creating opportunities to build a more resilient, successful, and cohesive society. Work organization and labor-force participation are central to both the opportunities and challenges posed by our aging society. We argue that expectations about old age have not sufficiently adapted to the reality of aging today. Our institutions need more adaptation in order to successfully face the consequences of demographic change. Although this adaptation needs to focus especially on work patterns among the “younger elderly,” our society has to change its general attitudes toward work organization and labor-force participation, which will have implications for education and health care. We also show that work’s beneficial effects on well-being in older ages are often neglected, while the idea that older workers displace younger workers is a misconception emerging from the “lump of labor” fallacy. We conclude, therefore, that working at older ages can lead to better quality of life for older people and to a more productive and resilient society overall. PMID:28042166

Ergonomics strategies and actions for achieving productive use of an ageing work-force.

PubMed

Kumashiro, M

2000-07-01

In this report, a basic ERGOMA (Ergonomics in Industrial Management) strategy is proposed as a policy for corporate production and employment in countries where ageing populations and reduced birth rates are imminent, and a strategy related to this is proposed. Specifically, as a strategy at the company level, the results of survey studies aimed at the development of methods for determining job capacity, to enable effective use of the labour of ageing workers, were summarized. A number of the insights gained here are steps in the development of a foundational methodology for practical use, and in actual practice a number of these insights must be subjected to measurements. However, the theory and newly developed methodology described here are thought to represent significant changes from the approaches to job capacity diagnosis and assessment published in the past and from the stance towards utilization of an ageing work-force. The author is confident that this represents new progress in one of the ergonomics approach to dealing with the working environment of ageing workers and an ageing work-force in general.

Experimental investigation of turbine blade-tip excitation forces

NASA Technical Reports Server (NTRS)

Martinez-Sanchez, Manuel; Jaroux, Belgacem; Song, Seung Jin; Yoo, Soom-Yung; Palczynski, Taras

1994-01-01

Results of a program to investigate the magnitude and parametric variations of rotordynamic forces which arise in high power turbines due to blade-tip leakage effects are presented. Five different unshrouded turbine configurations and one configuration shrouded with a labyrinth seal were tested with static offsets of the turbine shaft. The forces along and perpendicular to the offset were measured directly with a rotating dynometer. Exploration of casing pressure and flow velocity distributions was used to investigate the force-generating mechanisms. For unshrouded turbines, the cross-forces originate mainly from the classical Alford mechanisms while the direct forces arise mainly from a slightly skewed pressure pattern. The Alford coefficient for cross-force was found to vary between 2.4 and 4.0, while the similar direct force coefficient varied from 1.5 to 3.5. The cross-forces are found to increase substantially when the gap is reduced from 3.0 to 1.9% of blade height, probably due to viscous blade-tip effects. The forces also increase when the hub gap between stator and rotor decreases. The force coefficient decreased with operating flow coefficient. In the case of the shrouded turbine, most of the forces arise from nonuniform seal pressures. This includes about 80% for the transverse forces. The rest appears to come from uneven work extraction. Their level is about 50% higher in the shrouded case.

Shaping an Effective Parental-Leave Policy.

ERIC Educational Resources Information Center

Meiers, Margaret E.

1989-01-01

As increasing numbers of women and two-career couples enter the work force, parental leave provisions are becoming a routine business practice. Companies are beginning to recognize parental leave as a cost-effective strategy for retaining employees and maintaining productivity. (JOW)

Grasp Assist Device with Automatic Mode Control Logic

NASA Technical Reports Server (NTRS)

Laske, Evan (Inventor); Davis, Donald R. (Inventor); Ihrke, Chris A. (Inventor)

2018-01-01

A system includes a glove, sensors, actuator assemblies, and controller. The sensors include load sensors which measure an actual grasping force and attitude sensors which determine a glove attitude. The actuator assembly provides a grasp assist force to the glove. Respective locations of work cells in the work environment and permitted work tasks for each work cell are programmed into the controller. The controller detects the glove location and attitude. A work task is selected by the controller for the location. The controller calculates a required grasp assist force using measured actual grasping forces from the load sensors. The required grasp assist force is applied via the glove using the actuator assembly to thereby assist the operator in performing the identified work task.

State Workforce Policy Initiative.

ERIC Educational Resources Information Center

Public/Private Ventures, Philadelphia, PA.

Surging demand for workers, growing income inequality, and passage of welfare reforms have made work force development one of the United States' key national concerns. Public/Private Ventures has been working with various states to design work force development strategies that seek to address the concerns of many work force development specialists…

Numerical calculation and analysis of radial force on the single-action vane pump

NASA Astrophysics Data System (ADS)

Y He, Y.; Y Kong, F.

2013-12-01

Unbalanced radial force is a serious adversity that restricts the working pressure and reduces service life of the single-action vane pump. For revealing and predicting the distribution of radial force on the rotor, a numerical simulation about its transient flow field was performed by using dynamic mesh method with RNG κ ε-turbulent model. The details of transient flow characteristic and pressure fluctuation were obtained, and the radial force and periodic variation can be calculated based on the details. The results show: the radial force has a close relationship with the pressure pulsation; the radial force can be reduced drastically by optimizing the angle of port plate and installing the V-shaped cavity; if the odd number vanes are chosen, it will help reduce the radial force of rotor and optimize the pressure fluctuation effectively.

Note: A rigid piezo motor with large output force and an effective method to reduce sliding friction force.

PubMed

Guo, Ying; Hou, Yubin; Lu, Qingyou

2014-05-01

We present a completely practical TunaDrive piezo motor. It consists of a central piezo stack sandwiched by two arm piezo stacks and two leg piezo stacks, respectively, which is then sandwiched and spring-clamped by a pair of parallel polished sapphire rods. It works by alternatively fast expanding and contracting the arm/leg stacks while slowly expanding/contracting the central stack simultaneously. The key point is that sufficiently fast expanding and contracting a limb stack can make its two sliding friction forces well cancel, resulting in the total sliding friction force is <10% of the total static friction force, which can help increase output force greatly. The piezo motor's high compactness, precision, and output force make it perfect in building a high-quality harsh-condition (vibration resistant) atomic resolution scanning probe microscope.

Quantum fluctuation theorems and power measurements

NASA Astrophysics Data System (ADS)

Prasanna Venkatesh, B.; Watanabe, Gentaro; Talkner, Peter

2015-07-01

Work in the paradigm of the quantum fluctuation theorems of Crooks and Jarzynski is determined by projective measurements of energy at the beginning and end of the force protocol. In analogy to classical systems, we consider an alternative definition of work given by the integral of the supplied power determined by integrating up the results of repeated measurements of the instantaneous power during the force protocol. We observe that such a definition of work, in spite of taking account of the process dependence, has different possible values and statistics from the work determined by the conventional two energy measurement approach (TEMA). In the limit of many projective measurements of power, the system’s dynamics is frozen in the power measurement basis due to the quantum Zeno effect leading to statistics only trivially dependent on the force protocol. In general the Jarzynski relation is not satisfied except for the case when the instantaneous power operator commutes with the total Hamiltonian at all times. We also consider properties of the joint statistics of power-based definition of work and TEMA work in protocols where both values are determined. This allows us to quantify their correlations. Relaxing the projective measurement condition, weak continuous measurements of power are considered within the stochastic master equation formalism. Even in this scenario the power-based work statistics is in general not able to reproduce qualitative features of the TEMA work statistics.

Defense Standardization Program Journal, April/Jun 2007

DTIC Science & Technology

2007-06-01

Delivers Far-Reaching Standardization 9 Air Force Cyber Warfare Training 14 DMSMS Working Group Reaches Out to Programs 18 An Effects-Based Metrics...defend- ers their first 10 cyber warfare combat "sorties" and prepared them for net- work crew positions. Four MAJCOMs participated in BD 2002.The Air

TNT: Teams Need Training.

ERIC Educational Resources Information Center

Centre County Vocational-Technical School, Pleasant Gap, PA. CIU 10 Bi-County Development Center for Adults.

This document includes a final report and curriculum manual from a project to help adult educators teach team training by developing a curriculum for use in teaching teamwork skills in work force literacy programs and by providing two half-day seminars to assist adult educators with effectively using the curriculum. The manual for work force…

Child Care: A Business Investment That Works.

ERIC Educational Resources Information Center

Children's Action Alliance, Phoenix, AZ.

This publication explains to Arizona employers the effect of child care difficulties on the work force and profitablity and describes ways to help employees meet their child care needs. Discussion concerns the benefits of employee child care assistance programs, program options available to employees, and the steps required to implement the…

The Education Smokescreen.

ERIC Educational Resources Information Center

Weisman, Jonathan

1992-01-01

As success of one Toyota-managed auto plant shows, U.S. workers can produce as effectively and competitively when given good, work-specific training and a well-managed environment. By blaming their own faltering performance on inadequate work force skills, the nation's top chief executives have found a cheap, convenient way to scapegoat U.S.…

Farm Wives' Labor Force Participation and Earnings.

ERIC Educational Resources Information Center

Godwin, Deborah D.; Marlowe, Julia

1990-01-01

Examines relationship between employment earnings and farm wives' decisions to work off-farm. Examines effects of wives' human capital, home factors, and labor market on work decisions and earnings. Education, experience, debt, and farm size were stronger influences on wives' decisions than on their earnings variations, once employed. (TES)

Thermal imbalance force modelling for a GPS satellite using the finite element method

NASA Technical Reports Server (NTRS)

Vigue, Yvonne; Schutz, Bob E.

1991-01-01

Methods of analyzing the perturbation due to thermal radiation and determining its effects on the orbits of GPS satellites are presented, with emphasis on the FEM technique to calculate satellite solar panel temperatures which are used to determine the magnitude and direction of the thermal imbalance force. Although this force may not be responsible for all of the force mismodeling, conditions may work in combination with the thermal imbalance force to produce such accelerations on the order of 1.e-9 m/sq s. If submeter accurate orbits and centimeter-level accuracy for geophysical applications are desired, a time-dependent model of the thermal imbalance force should be used, especially when satellites are eclipsing, where the observed errors are larger than for satellites in noneclipsing orbits.

MEMS-Based Flexible Force Sensor for Tri-Axial Catheter Contact Force Measurement

PubMed Central

Sheng, Jun; Desai, Jaydev P.

2016-01-01

Atrial fibrillation (AFib) is a significant healthcare problem caused by the uneven and rapid discharge of electrical signals from pulmonary veins (PVs). The technique of radiofrequency (RF) ablation can block these abnormal electrical signals by ablating myocardial sleeves inside PVs. Catheter contact force measurement during RF ablation can reduce the rate of AFib recurrence, since it helps to determine effective contact of the catheter with the tissue, thereby resulting in effective power delivery for ablation. This paper presents the development of a three-dimensional (3D) force sensor to provide the real-time measurement of tri-axial catheter contact force. The 3D force sensor consists of a plastic cubic bead and five flexible force sensors. Each flexible force sensor was made of a PEDOT:PSS strain gauge and a PDMS bump on a flexible PDMS substrate. Calibration results show that the fabricated sensor has a linear response in the force range required for RF ablation. To evaluate its working performance, the fabricated sensor was pressed against gelatin tissue by a micromanipulator and also integrated on a catheter tip to test it within deionized water flow. Both experiments simulated the ventricular environment and proved the validity of applying the 3D force sensor in RF ablation. PMID:28190945

Agricultural Work Force Households: How Much Do They Depend on Farming? Background for Agricultural Policy. Agriculture Information Bulletin Number 547.

ERIC Educational Resources Information Center

Cox, E. Jane; Oliveira, Victor J.

According to data from the 1985 Agricultural Work Force Survey, over 13.5 million of the 17.6 million agricultural work force household members (77 percent) lived in households headed by a farm worker. Some farm workers worked on the farm as their primary job, whereas others primarily worked off the farm. Farm work was an occasional form of…

Dynamic dielectrophoresis model of multi-phase ionic fluids.

PubMed

Yan, Ying; Luo, Jing; Guo, Dan; Wen, Shizhu

2015-01-01

Ionic-based dielectrophoretic microchips have attracted significant attention due to their wide-ranging applications in electro kinetic and biological experiments. In this work, a numerical method is used to simulate the dynamic behaviors of ionic droplets in a microchannel under the effect of dielectrophoresis. When a discrete liquid dielectric is encompassed within a continuous fluid dielectric placed in an electric field, an electric force is produced due to the dielectrophoresis effect. If either or both of the fluids are ionic liquids, the magnitude and even the direction of the force will be changed because the net ionic charge induced by an electric field can affect the polarization degree of the dielectrics. However, using a dielectrophoresis model, assuming ideal dielectrics, results in significant errors. To avoid the inaccuracy caused by the model, this work incorporates the electrode kinetic equation and defines a relationship between the polarization charge and the net ionic charge. According to the simulation conditions presented herein, the electric force obtained in this work has an error exceeding 70% of the actual value if the false effect of net ionic charge is not accounted for, which would result in significant issues in the design and optimization of experimental parameters. Therefore, there is a clear motivation for developing a model adapted to ionic liquids to provide precise control for the dielectrophoresis of multi-phase ionic liquids.

40 CFR 35.936-14 - Force account work.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 1 2011-07-01 2011-07-01 false Force account work. 35.936-14 Section... ASSISTANCE STATE AND LOCAL ASSISTANCE Grants for Construction of Treatment Works-Clean Water Act § 35.936-14 Force account work. (a) A grantee must secure the project officer's prior written approval for use of...

Diversity in the Work Force. The Highlight Zone: Research @ Work No. 4.

ERIC Educational Resources Information Center

Wentling, Rose Mary

A literature review was conducted to identify critical work force diversity issues in today's changing workplace and identify ways organizations and career and technical education (CTE) practitioners can increase work force diversity. A broad, all-inclusive definition of diversity was developed that focuses on how diversity affects individuals and…

Employment perspectives of patients with ankylosing spondylitis.

PubMed

Chorus, A M J; Boonen, A; Miedema, H S; van der Linden, Sj

2002-08-01

To assess the labour market position of patients with ankylosing spondylitis (AS) in relation to disease duration and to identify potential factors in relation to withdrawal from the labour force. A cross sectional mail survey was conducted among 658 patients with AS. Participation in the labour force was defined as having a paid job. The independent effect of duration of disease was examined by an indirect method of standardisation. A broad variety of risk factors were examined separately and in a combined analysis, including sociodemographic factors, disease related variables, coping styles, and work related factors. Attributable and preventable fractions were calculated from the combined analyses to assess the relative importance of the contributing factors. Probability of participation in the labour force was similarly reduced in patients with AS with different durations of disease. Pacing to cope with limitations was the most relevant factor in increasing the risk of withdrawal from the labour force, accounting for 73% of withdrawals. Coping with limitations by often seeking creative solutions, high disease activity, increased age, and insufficient support from colleagues or management were also positively associated with withdrawal from the labour force. Technical or ergonomic adjustments of the workplace, working in large companies, and coping with dependency style through frequent acceptance were negatively associated. Of these factors, technical or ergonomic adjustment was the most relevant in terms of reducing the risk. Sociodemographic factors, disease related factors, coping styles, and work related factors contribute simultaneously to withdrawal from the labour force.

Effects of pretension on work and power output of the muscle-tendon complex in dynamic elbow flexion.

PubMed

Wakayama, Akinobu; Nagano, Akinori; Hay, Dean; Fukashiro, Senshi

2005-06-01

The purpose of the present study was to investigate the effects of pretension on work and power output of the muscle-tendon complex during dynamic elbow flexion under several submaximal and maximal conditions. The subjects were 10 healthy female students. Randomized trials from 0% to 100% maximal voluntary contraction (MVC) pretension (PT) at 60 degrees elbow flexion were conducted. After about 3 s of static PT, subjects maximally flexed the elbow joint to 90 degrees using a quick release method. The weight was individually selected for each subject to provide an optimal load for the development of maximal power. A Hill-type model was utilized to analyze the performance of the elbow muscle-tendon complex (MTC). PT 0, 30, 60 and 90% MVC data were used for comparison, and all data were expressed as the mean and standard deviation. Multiple paired comparisons between the value of PT 0% MVC and that of the other PT levels were performed post-hoc using Dunnett's method. The work of the series elastic component (SEC) increased gradually with the PT level because elastic energy was stored in the PT phase. However, the work of the contractile component (CC) decreased gradually with an increase in PT level. Moreover, the work of the MTC also decreased, closely related to the CC work decrement. The phenomenon of CC work decrement was caused by force depression and was not related to either the force-length or force-velocity relationships of the CC. EMG activity (agonist and antagonist) showed no significant differences. Muscle geometry changes or intracellular chemical shifts may have occurred in the PT phase.

Compressibility Effects on Particle-Fluid Interaction Force for Eulerian-Eulerian Simulations

NASA Astrophysics Data System (ADS)

Akiki, Georges; Francois, Marianne; Zhang, Duan

2017-11-01

Particle-fluid interaction forces are essential in modeling multiphase flows. Several models can be found in the literature based on empirical, numerical, and experimental results from various simplified flow conditions. Some of these models also account for finite Mach number effects. Using these models is relatively straightforward with Eulerian-Lagrangian calculations if the model for the total force on particles is used. In Eulerian-Eulerian simulations, however, there is the pressure gradient terms in the momentum equation for particles. For low Mach number flows, the pressure gradient force is negligible if the particle density is much greater than that of the fluid. For supersonic flows where a standing shock is present, even for a steady and uniform flow, it is unclear whether the significant pressure-gradient force should to be separated out from the particle force model. To answer this conceptual question, we perform single-sphere fully-resolved DNS simulations for a wide range of Mach numbers. We then examine whether the total force obtained from the DNS can be categorized into well-established models, such as the quasi-steady, added-mass, pressure-gradient, and history forces. Work sponsored by Advanced Simulation and Computing (ASC) program of NNSA and LDRD-CNLS of LANL.

Overspinning a Kerr black hole: The effect of the self-force

NASA Astrophysics Data System (ADS)

Colleoni, Marta; Barack, Leor

2015-05-01

We study the scenario in which a massive particle is thrown into a rapidly rotating Kerr black hole in an attempt to spin it up beyond its extremal limit, challenging weak cosmic censorship. We work in black-hole perturbation theory, and focus on nonspinning, uncharged particles sent in on equatorial orbits. We first identify the complete parameter-space region in which overspinning occurs when backreaction effects from the particle's self-gravity are ignored. We find, in particular, that overspinning can be achieved only with particles sent in from infinity. Gravitational self-force effects may prevent overspinning by radiating away a sufficient amount of the particle's angular momentum ("dissipative effect"), and/or by increasing the effective centrifugal repulsion, so that particles with suitable parameters never get captured ("conservative effect"). We analyze the full effect of the self-force, thereby completing previous studies by Jacobson and Sotiriou (who neglected the self-force) and by Barausse, Cardoso and Khanna (who considered the dissipative effect on a subset of orbits). Our main result is an inequality, involving certain self-force quantities, which describes a necessary and sufficient condition for the overspinning scenario to be overruled. This "censorship" condition is formulated on a certain one-parameter family of geodesics in the limit of an extremal Kerr geometry. We find that the censorship condition is insensitive to the dissipative effect (within the first-order self-force approximation used here), except for a subset of perfectly fine-tuned orbits, for which a separate censorship condition is derived. We do not obtain here the self-force input needed to evaluate either of our two conditions, but discuss the prospects for producing the necessary data using state-of-the-art numerical codes.

Force Generation in Single Conventional Actomyosin Complexes under High Dynamic Load

PubMed Central

Takagi, Yasuharu; Homsher, Earl E.; Goldman, Yale E.; Shuman, Henry

2006-01-01

The mechanical load borne by a molecular motor affects its force, sliding distance, and its rate of energy transduction. The control of ATPase activity by the mechanical load on a muscle tunes its efficiency to the immediate task, increasing ATP hydrolysis as the power output increases at forces less than isometric (the Fenn effect) and suppressing ATP hydrolysis when the force is greater than isometric. In this work, we used a novel ‘isometric’ optical clamp to study the mechanics of myosin II molecules to detect the reaction steps that depend on the dynamic properties of the load. An actin filament suspended between two beads and held in separate optical traps is brought close to a surface that is sparsely coated with motor proteins on pedestals of silica beads. A feedback system increases the effective stiffness of the actin by clamping the force on one of the beads and moving the other bead electrooptically. Forces measured during actomyosin interactions are increased at higher effective stiffness. The results indicate that single myosin molecules transduce energy nearly as efficiently as whole muscle and that the mechanical control of the ATP hydrolysis rate is in part exerted by reversal of the force-generating actomyosin transition under high load without net utilization of ATP. PMID:16326899

Effectiveness of video-assisted teaching program on safety measures followed by the employees working in the silica-based industry in Puducherry, India

PubMed Central

Nanthini, Thiruvengadam; Karunagari, Karaline

2016-01-01

Introduction: Employees constitute a large and important sector of the world's population. The global labor force is about 2,600 million and 75% of this force is working in developing countries. Occupational health and safety (OHS) must be managed in every aspect of their work. Occupational safety and health (OSH), also commonly referred to as OHS or workplace health and safety (WHS) is an area concerned with the safety, health, and welfare of people engaged in any employment. The goal of OSH is to foster a safe and healthy work environment. The aim of this study is to evaluate the effectiveness of video-assisted teaching program on safety measures. Materials and Methods: A total of 105 employees were selected from M/s ACE Glass Containers Ltd. at Puducherry, India using the convenience sampling technique. Pretest was conducted using a self-administered questionnaire. Subsequent video-assisted teaching was conducted by the investigator after which posttest was conducted. Results and Conclusion: Video-assisted teaching program was found to be effective in improving the knowledge, attitude, and practice of the subjects. Periodical reorientation on safety measures are needed for all the employees as it is essential for promoting the well-being of employees working in any industry. PMID:27390477

Effectiveness of video-assisted teaching program on safety measures followed by the employees working in the silica-based industry in Puducherry, India.

PubMed

Nanthini, Thiruvengadam; Karunagari, Karaline

2016-01-01

Employees constitute a large and important sector of the world's population. The global labor force is about 2,600 million and 75% of this force is working in developing countries. Occupational health and safety (OHS) must be managed in every aspect of their work. Occupational safety and health (OSH), also commonly referred to as OHS or workplace health and safety (WHS) is an area concerned with the safety, health, and welfare of people engaged in any employment. The goal of OSH is to foster a safe and healthy work environment. The aim of this study is to evaluate the effectiveness of video-assisted teaching program on safety measures. A total of 105 employees were selected from M/s ACE Glass Containers Ltd. at Puducherry, India using the convenience sampling technique. Pretest was conducted using a self-administered questionnaire. Subsequent video-assisted teaching was conducted by the investigator after which posttest was conducted. Video-assisted teaching program was found to be effective in improving the knowledge, attitude, and practice of the subjects. Periodical reorientation on safety measures are needed for all the employees as it is essential for promoting the well-being of employees working in any industry.

Development of Alternative Continuing Educational Systems for Preventing the Technological Obsolescence of Air Force Scientists and Engineers. Volume 1. Basic Study.

ERIC Educational Resources Information Center

Slebodnick, Edward B.; And Others

Volume 1 of the study reports a work effort to define and give guidelines for the acquisition of cost-effective alternative continuing education (CE) systems to prevent the technological obsolescence of Air Force military scientific and engineering officer personnel. A detailed background survey of the problem was conducted using questionnaires,…

In-vivo force decay of nickel-titanium closed-coil springs.

PubMed

Cox, Crystal; Nguyen, Tung; Koroluk, Lorne; Ko, Ching-Chang

2014-04-01

Nickel-titanium closed-coil springs are purported to deliver constant forces over extended ranges of activation and working times. In-vivo studies supporting this claim are limited. The objective of this study was to evaluate changes in force-decay properties of nickel-titanium closed-coil springs after clinical use. Pseudoelastic force-deflection curves for 30 nickel-titanium coil springs (used intraorally) and 15 matched laboratory control springs (simulated intraoral conditions: artificial saliva, 37°C) were tested before and after retrieval via dynamic mechanical analysis and a testing machine, respectively, to evaluate the amounts of force-loss and hysteresis change after 4, 8, or 12 weeks of working time (n = 10 per group). The effects of the oral environment and clinical use on force properties were evaluated by comparing in-vivo and in-vitro data. The springs studied showed a statistically significant decrease in force (approximately 12%) after 4 weeks of clinical use (P <0.01), with a further significant decrease (approximately 7%) from 4 to 8 weeks (P = 0.03), and force levels appearing to remain steady thereafter. Clinical space closure at an average rate of 0.91 mm per month was still observed despite this decrease in force. In-vivo and in-vitro force-loss data were not statistically different. Nickel-titanium closed-coil springs do not deliver constant forces when used intraorally, but they still allow for space-closure rates of approximately 1 mm per month. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Effect of proline kinks on the mechanical unfolding of α-helices

NASA Astrophysics Data System (ADS)

Arteca, Gustavo A.; Li, Zhiying

2004-12-01

Proteins unfold by applying an external force, although the microscopic mechanism is still not well understood. In this work, we use steered molecular dynamics to probe fundamental aspects of the stretching transition of α-helices, in particular how proline kinks and side chain dynamics would influence their ability to resist the applied force. We find that proline residues effectively 'cut' a helix in half when introduced on stable homopolymers, whereas their effect is smaller when present in helices that are more easily deformed. Our findings provide insight into the factors that may regulate the mechanical stretching of realistic protein domains.

Evaluation of knee joint forces during kneeling work with different kneepads.

PubMed

Xu, Hang; Jampala, Sree; Bloswick, Donald; Zhao, Jie; Merryweather, Andrew

2017-01-01

The main purpose of this study is to determine knee joint forces resulting from kneeling work with and without kneepads to quantify how different kneepads redistribute force. Eleven healthy males simulated a tile setting task to different locations during six kneepad states (five different kneepad types and without kneepad). Peak and average forces on the anatomical landmarks of both knees were obtained by custom force sensors. The results revealed that kneepad design can significantly modify the forces on the knee joint through redistribution. The Professional Gel design was preferred among the five tested kneepads which was confirmed with both force measurements and participants' responses. The extreme reaching locations induced significantly higher joint forces on left knee or right knee depending on task. The conclusion of this study is that a properly selected kneepad for specific tasks and a more neutral working posture can modify the force distribution on the knees and likely decrease the risk of knee disorders from kneeling work. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evidence for non-conservative current-induced forces in the breaking of Au and Pt atomic chains

PubMed Central

Sabater, Carlos; Untiedt, Carlos

2015-01-01

Summary This experimental work aims at probing current-induced forces at the atomic scale. Specifically it addresses predictions in recent work regarding the appearance of run-away modes as a result of a combined effect of the non-conservative wind force and a ‘Berry force’. The systems we consider here are atomic chains of Au and Pt atoms, for which we investigate the distribution of break down voltage values. We observe two distinct modes of breaking for Au atomic chains. The breaking at high voltage appears to behave as expected for regular break down by thermal excitation due to Joule heating. However, there is a low-voltage breaking mode that has characteristics expected for the mechanism of current-induced forces. Although a full comparison would require more detailed information on the individual atomic configurations, the systems we consider are very similar to those considered in recent model calculations and the comparison between experiment and theory is very encouraging for the interpretation we propose. PMID:26734525

Assessing implicit models for nonpolar mean solvation forces: The importance of dispersion and volume terms

PubMed Central

Wagoner, Jason A.; Baker, Nathan A.

2006-01-01

Continuum solvation models provide appealing alternatives to explicit solvent methods because of their ability to reproduce solvation effects while alleviating the need for expensive sampling. Our previous work has demonstrated that Poisson-Boltzmann methods are capable of faithfully reproducing polar explicit solvent forces for dilute protein systems; however, the popular solvent-accessible surface area model was shown to be incapable of accurately describing nonpolar solvation forces at atomic-length scales. Therefore, alternate continuum methods are needed to reproduce nonpolar interactions at the atomic scale. In the present work, we address this issue by supplementing the solvent-accessible surface area model with additional volume and dispersion integral terms suggested by scaled particle models and Weeks–Chandler–Andersen theory, respectively. This more complete nonpolar implicit solvent model shows very good agreement with explicit solvent results and suggests that, although often overlooked, the inclusion of appropriate dispersion and volume terms are essential for an accurate implicit solvent description of atomic-scale nonpolar forces. PMID:16709675

Did the Americanization Movement Succeed? An Evaluation of the Effect of English-Only and Compulsory Schools Laws on Immigrants' Education. NBER Working Paper No. 18302

ERIC Educational Resources Information Center

Lleras-Muney, Adriana; Shertzer, Allison

2012-01-01

In the early twentieth century, education legislation was often passed based on arguments that new laws were needed to force immigrants to learn English and "Americanize." We provide the first estimates of the effect of statutes requiring English as the language of instruction and compulsory schooling laws on the school enrollment, work, literacy…

U.S. Department of Energy, Office of Legacy Management Program Update, April-June 2009

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2009-04-01

Welcome to the April-June 2009 issue of the U.S. Department of Energy (DOE) Office of Legacy Management (LM) Program Update. This publication is designed to provide a status of activities within LM. The Legacy Management goals are: (1) Protect human health and the environment through effective and efficient long-term surveillance and maintenance - This goal highlights DOE's responsibility to ensure long-term protection of people, the environment, and the integrity of engineered remedies and monitoring systems. (2) Preserve, protect, and make accessible legacy records and information - This goal recognizes LM's commitment to successfully manage records, information, and archives of legacymore » sites under its authority. (3) Support an effective and efficient work force structured to accomplish Departmental missions and assure continuity of contractor worker pension and medical benefits - This goal recognizes DOE's commitment to its contracted work force and the consistent management of pension and health benefits. As sites continue to close, DOE faces the challenges of managing pension plan and health benefits liability. (4) Manage legacy land and assets, emphasizing protective real and personal property reuse and disposition - This goal recognizes a DOE need for local collaborative management of legacy assets, including coordinating land use planning, personal property disposition to community reuse organizations, and protecting heritage resources (natural, cultural, and historical). (5) Improve program effectiveness through sound management - This goal recognizes that LM's goals cannot be attained efficiently unless the federal and contractor work force is motivated to meet requirements and work toward continuous performance improvement.« less

Effective Schools: Teacher Hiring, Assignment, Development, and Retention. NBER Working Paper No. 17177

ERIC Educational Resources Information Center

Loeb, Susanna; Kalogrides, Demetra; Beteille, Tara

2011-01-01

The literature on effective schools emphasizes the importance of a quality teaching force in improving educational outcomes for students. In this paper, we use value-added methods to examine the relationship between a school's effectiveness and the recruitment, assignment, development and retention of its teachers. We ask whether effective schools…

Flow Physics and Control for Internal and External Aerodynamics

NASA Technical Reports Server (NTRS)

Wygnanski, I.

2010-01-01

Exploiting instabilities rather than forcing the flow is advantageous. Simple 2D concepts may not always work. Nonlinear effects may result in first order effect. Interaction between spanwise and streamwise vortices may have a paramount effect on the mean flow, but this interaction may not always be beneficial.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maurer, D.

In January 1986, the Becon Construction Company - an open-shop contractor based in Houston, Texas - mobilized a work force to a construction project location at the Belridge Oil Field, near Bakersfield, California. The construction craftsmen and helpers in Becon's work force were expected to improve their level of productivity as the work proceeded because of the knowledge and skills that they would acquire as a result of the repetitive nature of the work. As it was originally organized, the Becon HOTS project represented almost a pure laboratory environment in which to collect data concerning the learning effect on workermore » productivity as well as to statistically isolate the impact on productivity of such external factors as weather, absenteeism, turnover, and especially work methods improvement techniques and pay incentives. From the outset of the HOTS project, the project manager had established an accurate system to quantitatively measure and compare the total manhours that each crew - civil, mechanical, electrical, and prefabrication -- performed at individual HOTS construction locations. Additionally, it was initially assumed that the project manager would be relatively free to implement changes to the job site conditions involving incentive pay and work methods improvement. The subsequent effect of these changes on the productivity of separate work crews could then be evaluated in terms of measured manhours per crew per HOTS.« less

The Work, the Workplace, and the Work Force of Tomorrow.

ERIC Educational Resources Information Center

Allen, Claudia

1995-01-01

Ann McLaughlin, a former secretary of labor, discusses her views on the future of the workplace. She feels that to solve the impending problem of educational deficits among the work force, employers will begin their own educational programs, improving both employee loyalty and work force mobility. Includes predictions for future growth fields.…

The role of visual and direct force feedback in robotics-assisted mitral valve annuloplasty.

PubMed

Currie, Maria E; Talasaz, Ali; Rayman, Reiza; Chu, Michael W A; Kiaii, Bob; Peters, Terry; Trejos, Ana Luisa; Patel, Rajni

2017-09-01

The objective of this work was to determine the effect of both direct force feedback and visual force feedback on the amount of force applied to mitral valve tissue during ex vivo robotics-assisted mitral valve annuloplasty. A force feedback-enabled master-slave surgical system was developed to provide both visual and direct force feedback during robotics-assisted cardiac surgery. This system measured the amount of force applied by novice and expert surgeons to cardiac tissue during ex vivo mitral valve annuloplasty repair. The addition of visual (2.16 ± 1.67), direct (1.62 ± 0.86), or both visual and direct force feedback (2.15 ± 1.08) resulted in lower mean maximum force applied to mitral valve tissue while suturing compared with no force feedback (3.34 ± 1.93 N; P < 0.05). To achieve better control of interaction forces on cardiac tissue during robotics-assisted mitral valve annuloplasty suturing, force feedback may be required. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of precision demands and mental pressure on muscle activation and hand forces in computer mouse tasks.

PubMed

Visser, Bart; De Looze, Michiel; De Graaff, Matthijs; Van Dieën, Jaap

2004-02-05

The objective of the present study was to gain insight into the effects of precision demands and mental pressure on the load of the upper extremity. Two computer mouse tasks were used: an aiming and a tracking task. Upper extremity loading was operationalized as the myo-electric activity of the wrist flexor and extensor and of the trapezius descendens muscles and the applied grip- and click-forces on the computer mouse. Performance measures, reflecting the accuracy in both tasks and the clicking rate in the aiming task, indicated that the levels of the independent variables resulted in distinguishable levels of accuracy and work pace. Precision demands had a small effect on upper extremity loading with a significant increase in the EMG-amplitudes (21%) of the wrist flexors during the aiming tasks. Precision had large effects on performance. Mental pressure had substantial effects on EMG-amplitudes with an increase of 22% in the trapezius when tracking and increases of 41% in the trapezius and 45% and 140% in the wrist extensors and flexors, respectively, when aiming. During aiming, grip- and click-forces increased by 51% and 40% respectively. Mental pressure had small effects on accuracy but large effects on tempo during aiming. Precision demands and mental pressure in aiming and tracking tasks with a computer mouse were found to coincide with increased muscle activity in some upper extremity muscles and increased force exertion on the computer mouse. Mental pressure caused significant effects on these parameters more often than precision demands. Precision and mental pressure were found to have effects on performance, with precision effects being significant for all performance measures studied and mental pressure effects for some of them. The results of this study suggest that precision demands and mental pressure increase upper extremity load, with mental pressure effects being larger than precision effects. The possible role of precision demands as an indirect mental stressor in working conditions is discussed.

Managing cultural diversity in the workplace.

PubMed

Hubbard, J

1993-07-01

Cultural diversity is a strength of the American work force. Due to the increasing cultural diversity in the workplace, organizations find it in their best interest to move beyond affirmative action to effective management to achieve higher employee retention and develops an employee cultural mix that better matches the mix of the available labor force and customer base. To manage a diverse work force, managers need to have the proper tools, training and evaluation and monitoring programs. Important initiatives to successful management of cultural diversity include eliciting support and commitment from the board of directors, the CEO and other top management; organizing subcommittees to research and monitor demographic changes to determine what the organization's goals should be and to decide what changes are to be made. Employees must be trained to be aware of prejudices and how to manage their own actions.

The influence of tip shape on bending force during needle insertion

PubMed Central

van de Berg, Nick J.; de Jong, Tonke L.; van Gerwen, Dennis J.; Dankelman, Jenny; van den Dobbelsteen, John J.

2017-01-01

Steering of needles involves the planning and timely modifying of instrument-tissue force interactions to allow for controlled deflections during the insertion in tissue. In this work, the effect of tip shape on these forces was studied using 10 mm diameter needle tips. Six different tips were selected, including beveled and conical versions, with or without pre-bend or pre-curve. A six-degree-of-freedom force/torque sensor measured the loads during indentations in tissue simulants. The increased insertion (axial) and bending (radial) forces with insertion depth — the force-displacement slopes — were analyzed. Results showed that the ratio between radial and axial forces was not always proportional. This means that the tip load does not have a constant orientation, as is often assumed in mechanics-based steering models. For all tip types, the tip-load assumed a more radial orientation with increased axial load. This effect was larger for straight tips than for pre-bent or pre-curved tips. In addition, the force-displacement slopes were consistently higher for (1) increased tip angles, and for (2) beveled tips compared to conical tips. Needles with a bent or curved tip allow for an increased bending force and a decreased variability of the tip load vector orientation. PMID:28074939

Note: A rigid piezo motor with large output force and an effective method to reduce sliding friction force

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Ying; Lu, Qingyou, E-mail: qxl@ustc.edu.cn; Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026

2014-05-15

We present a completely practical TunaDrive piezo motor. It consists of a central piezo stack sandwiched by two arm piezo stacks and two leg piezo stacks, respectively, which is then sandwiched and spring-clamped by a pair of parallel polished sapphire rods. It works by alternatively fast expanding and contracting the arm/leg stacks while slowly expanding/contracting the central stack simultaneously. The key point is that sufficiently fast expanding and contracting a limb stack can make its two sliding friction forces well cancel, resulting in the total sliding friction force is <10% of the total static friction force, which can help increasemore » output force greatly. The piezo motor's high compactness, precision, and output force make it perfect in building a high-quality harsh-condition (vibration resistant) atomic resolution scanning probe microscope.« less

The labor force of the future.

PubMed

Norwood, J L

1987-07-01

In the decades ahead, the US labor force will reflect changes in the industrial structure, with declines in some manufacturing industries and expansion in service industries. The services sector is so diverse that the jobs within it cannot be categorized as either high wage or low wage. The service-producing sector employs 85% of professional specialty workers in the US. In general, information on compensation trends indicates that greater increases in compensation have occurred for workers in service-producing as opposed to goods-producing industries. The increase in service sector jobs has created opportunities for women to enter the labor force and, at present, 5 out of 6 women work in this sector compared to fewer than 2 out of 3 men. Productivity growth rates in the service-producing industries vary substantially and are strongly affected by the business cycle. Central to employment opportunities in the years ahead will be the effect of new technology. To date, the aggregate effect of new technology has been increased employment and higher living standards. Although retraining programs should be in place, the scenario of a huge technology-created labor surplus seems unlikely. In fact, a more likely problem is a shortage of labor resulting from earlier labor force withdrawal and demographic aging of the population. Those in the 25-54-year age group will represent a larger share of the labor force in the years ahead. In addition, blacks are expected to account for 20% of the labor force growth in the next decade. Finally, given increasing labor force participation rates among mothers, employers may have to provide more flexible work schedules, assistance with day care, and more attractive benefits packages.

Influence of the conservative rotor loads on the near wake of a wind turbine

NASA Astrophysics Data System (ADS)

Herráez, I.; Micallef, D.; van Kuik, G. A. M.

2017-05-01

The presence of conservative forces on rotor blades is neglected in the blade element theory and all the numerical methods derived from it (like e.g. the blade element momentum theory and the actuator line technique). This might seem a reasonable simplification of the real flow of rotor blades, since conservative loads, by definition, do not contribute to the power conversion. However, conservative loads originating from the chordwise bound vorticity might affect the tip vortex trajectory, as we discussed in a previous work. In that work we also hypothesized that this effect, in turn, could influence the wake induction and correspondingly the rotor performance. In the current work we extend a standard actuator line model in order to account for the conservative loads at the blade tip. This allows to isolate the influence of conservative forces from other effects. The comparison of numerical results with and without conservative loads enables to confirm qualitatively their relevance for the near wake and the rotor performance. However, an accurate quantitative assessment of the effect still remains out of reach due to the inherent uncertainty of the numerical model.

Model for Efficient and Effective Footnote Disclosure in Pedagogical and Practitioner Application

ERIC Educational Resources Information Center

Bullen, Maria L.; Kordecki, Gregory S.

2014-01-01

In the U.S. and in other countries, accounting graduates continue to enter diverse size work forces in industry, government, and in public accounting. Beyond income tax and consulting work, accounting professionals often require a specific association with financial statement services. These services involve not only detailed scheduled financial…

Will America Choose High Skills or Low Wages?

ERIC Educational Resources Information Center

Magaziner, Ira; Clinton, Hillary Rodham

1992-01-01

To compete more effectively in the global economy, the U.S. must reorganize the way people work in stores, factories, and elsewhere. Two factors hinder production of a highly educated work force: lack of a clear standard of achievement and insufficient student motivation. A new educational performance standard (Certificate of Initial Mastery) is…

The Labor-Supply Response of Married Women, Husband Present

ERIC Educational Resources Information Center

Cain, Glen G.

1974-01-01

The labor-supply or work-effect response of married women with husband present of families eligible for or receiving subsidies such as negative income tax (Graduated Work Incentive Experiment-New Jersey, Pennsylvania) revealed significant disincentive toward labor-force participation for white wives but not for black and Spanish-speaking wives.…

76 FR 19023 - Commercial Driver's License Information System State Procedures Manual, Release 5.2.0

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-06

... public docket for this rulemaking. In August 2005, section 4123 of the Safe, Accountable, Flexible... force and effect of law. V. Implementation Date The Agency is currently working with AAMVA and the... are currently working to pass required implementing legislation, modify their information systems to...

Effect of Coriolis force on counter-current chromatographic separation by centrifugal partition chromatography.

PubMed

Ikehata, Jun-Ichi; Shinomiya, Kazufusa; Kobayashi, Koji; Ohshima, Hisashi; Kitanaka, Susumu; Ito, Yoichiro

2004-02-06

The effect of Coriolis force on the counter-current chromatographic separation was studied using centrifugal partition chromatography (CPC) with four different two-phase solvent systems including n-hexane-acetonitrile (ACN); tert-butyl methyl ether (MtBE)-aqueous 0.1% trifluoroacetic acid (TFA) (1:1); MtBE-ACN-aqueous 0.1% TFA (2:2:3); and 12.5% (w/w) polyethylene glycol (PEG) 1000-12.5% (w/w) dibasic potassium phosphate. Each separation was performed by eluting either the upper phase in the ascending mode or the lower phase in the descending mode, each in clockwise (CW) and counterclockwise column rotation. Better partition efficiencies were attained by the CW rotation in both mobile phases in all the two-phase solvent systems examined. The mathematical analysis also revealed the Coriolis force works favorably under the CW column rotation for both mobile phases. The overall results demonstrated that the Coriolis force produces substantial effects on CPC separation in both organic-aqueous and aqueous-aqueous two-phase systems.

Acoustic forcing of a liquid drop

NASA Technical Reports Server (NTRS)

Lyell, M. J.

1992-01-01

The development of systems such as acoustic levitation chambers will allow for the positioning and manipulation of material samples (drops) in a microgravity environment. This provides the capability for fundamental studies in droplet dynamics as well as containerless processing work. Such systems use acoustic radiation pressure forces to position or to further manipulate (e.g., oscillate) the sample. The primary objective was to determine the effect of a viscous acoustic field/tangential radiation pressure forcing on drop oscillations. To this end, the viscous acoustic field is determined. Modified (forced) hydrodynamic field equations which result from a consistent perturbation expansion scheme are solved. This is done in the separate cases of an unmodulated and a modulated acoustic field. The effect of the tangential radiation stress on the hydrodynamic field (drop oscillations) is found to manifest as a correction to the velocity field in a sublayer region near the drop/host interface. Moreover, the forcing due to the radiation pressure vector at the interface is modified by inclusion of tangential stresses.

Ultrasound - Aided ejection in micro injection molding

NASA Astrophysics Data System (ADS)

Masato, D.; Sorgato, M.; Lucchetta, G.

2018-05-01

In this work, an ultrasound-aided ejection system was designed and tested for different polymers (PS, COC and POM) and mold topographies. The proposed solution aims at reducing the ejection friction by decreasing the adhesion component of the frictional force, which is controlled by the contact area developed during the filling stage of the injection molding process. The experimental results indicate a positive effect of ultrasound vibration on the friction force values, with a maximum reduction of 16. Moreover, it is demonstrated that the ultrasound effect is strictly related to both polymer selection and mold roughness. The combined effect on the ejection force of mold surface roughness, melt viscosity during filling and polymer elastic modulus at ejection was modeled to the experimental data, in order to demonstrate that the effect of ultrasound vibration on the ejection friction reduction is due to the heating of the contact interface and the consequent reduction of the polymer elastic modulus.

Development of Three-Dimensional Flow Code Package to Predict Performance and Stability of Aircraft with Leading Edge Ice Contamination

NASA Technical Reports Server (NTRS)

Strash, D. J.; Summa, J. M.

1996-01-01

In the work reported herein, a simplified, uncoupled, zonal procedure is utilized to assess the capability of numerically simulating icing effects on a Boeing 727-200 aircraft. The computational approach combines potential flow plus boundary layer simulations by VSAERO for the un-iced aircraft forces and moments with Navier-Stokes simulations by NPARC for the incremental forces and moments due to iced components. These are compared with wind tunnel force and moment data, supplied by the Boeing Company, examining longitudinal flight characteristics. Grid refinement improved the local flow features over previously reported work with no appreciable difference in the incremental ice effect. The computed lift curve slope with and without empennage ice matches the experimental value to within 1%, and the zero lift angle agrees to within 0.2 of a degree. The computed slope of the un-iced and iced aircraft longitudinal stability curve is within about 2% of the test data. This work demonstrates the feasibility of a zonal method for the icing analysis of complete aircraft or isolated components within the linear angle of attack range. In fact, this zonal technique has allowed for the viscous analysis of a complete aircraft with ice which is currently not otherwise considered tractable.

Force and light tuning vertical tunneling current in the atomic layered MoS2.

PubMed

Li, Feng; Lu, Zhixing; Lan, Yann-Wen; Jiao, Liying; Xu, Minxuan; Zhu, Xiaoyang; Zhang, Xiankun; Wu, Hualin; Qi, Junjie

2018-07-06

In this work, the vertical electrical transport behavior of bilayer MoS 2 under the coupling of force and light was explored by the use of conductive atomic force microscopy. We found that the current-voltage behavior across the tip-MoS 2 -Pt junction is a tunneling current that can be well fitted by a Simmons approximation. The transport behavior is direct tunneling at low bias and Fowler-Nordheim tunneling at high bias, and the transition voltage and tunnel barrier height are extracted. The effect of force and light on the effective band gap of the junction is investigated. Furthermore, the source-drain current drops surprisingly when we continually increase the force, and the dropping point is altered by the provided light. This mechanism is responsible for the tuning of tunneling barrier height and width by force and light. These results provide a new way to design devices that take advantage of ultrathin two-dimensional materials. Ultrashort channel length electronic components that possess tunneling current are important for establishing high-efficiency electronic and optoelectronic systems.

World and regional labour force trends and prospects.

PubMed

Ypsilantis, J N

1974-01-01

Changes in fertility during 1970-1985 will not have any effect on the composition of the world work force until 1985 because the people who will be of working age at that time have already been born. However, fertility for this period will directly influence the size of the age group 15-30 in the year 2000. Moreover, fertility trends for this period will have an indirect effect on participation of women in the labor force. The number of people in the labor force has proportionately followed total population. Just as total population is projected to increase in the single decade 1970-1980 by an amount equal to its size in 1750, so the labor force will increase by 360 million during the 1980's (its original size in 1750). By the end of the present century the world labor force may well number some 2,6000 million, reaching 3,000 million by the year 2010; 4,000 million by 2030; 5,000 million by 2070; and stabilizing at about 5,200 million by the end of the 21st century. There will be great regional variations. Increases will range from 20-35% in Europe and the U.S.S.R. to 100-120% in South Asia, Africa, and Latin America. For East Asia and North America the increases may amount to 60% by the year 2000 and 100% by 2050. In 1970 less developed regions had 2/3 the world's labor force; by 2000 they will have 3/4. In 1970 about 20% of the labor force in more developed regions were working in agriculture while in less developed regions 2/3 were so engaged. In other terms, in more developed regions 10 farmers supported 108 persons while in less developed regions 10 farmers supported only 38. According to Food and Agriculture Organization projections, by 2000 only 3.5% of the labor force in developed regions and 43.5% in less developed regions will be in agriculture. Differences in gross national product between regions is striking. In 1970 the less developed regions contained 70% of world population, 67% of the world labor force, 87% of the world agricultural labor, and produced 15% of its wealth. There are also sharp contrasts in participation in the labor force. In less developed countries more youths and older persons are in the labor force while in developed countries more women work. By the year 2000 female activity rates in more developed regions will increase for ages 20-64 and decrease for those under 20 and over 64. This will raise female participation in the labor force to 35%. In less developed regions female participation is expected to decline. The proportion of young workers is expected to increase in less developed and decline in more developed regions; the same will be true for older workers. The dependency burden will be concentrated among the young in less developed nations; in more devel oped regions there will be larger numbers of older dependents.

48 CFR 223.570 - Drug-free work force.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Drug-free work force. 223.570 Section 223.570 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM... TECHNOLOGIES, OCCUPATIONAL SAFETY, AND DRUG-FREE WORKPLACE Drug-Free Workplace 223.570 Drug-free work force. ...

48 CFR 223.570 - Drug-free work force.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 48 Federal Acquisition Regulations System 3 2011-10-01 2011-10-01 false Drug-free work force. 223.570 Section 223.570 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM... TECHNOLOGIES, OCCUPATIONAL SAFETY, AND DRUG-FREE WORKPLACE Drug-Free Workplace 223.570 Drug-free work force. ...

48 CFR 223.570 - Drug-free work force.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 48 Federal Acquisition Regulations System 3 2013-10-01 2013-10-01 false Drug-free work force. 223.570 Section 223.570 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM... TECHNOLOGIES, OCCUPATIONAL SAFETY, AND DRUG-FREE WORKPLACE Drug-Free Workplace 223.570 Drug-free work force. ...

48 CFR 223.570 - Drug-free work force.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 48 Federal Acquisition Regulations System 3 2012-10-01 2012-10-01 false Drug-free work force. 223.570 Section 223.570 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM... TECHNOLOGIES, OCCUPATIONAL SAFETY, AND DRUG-FREE WORKPLACE Drug-Free Workplace 223.570 Drug-free work force. ...

48 CFR 223.570 - Drug-free work force.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 48 Federal Acquisition Regulations System 3 2014-10-01 2014-10-01 false Drug-free work force. 223.570 Section 223.570 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM... TECHNOLOGIES, OCCUPATIONAL SAFETY, AND DRUG-FREE WORKPLACE Drug-Free Workplace 223.570 Drug-free work force. ...

Internal Aspects of the Skill Transfer of Manual Assembly Work

ERIC Educational Resources Information Center

Doyo, Daisuke

2009-01-01

In manual assembly work, parts are often assembled by applying force with a simple tool or by hand. A worker thus needs control the force he or she applies in working, as an appropriate level of force is requisite for minimizing work failures and improving efficiency. The object of this study is to clarify the relationship between the level of…

Employment in Perspective: Women in the Labor Force. Third Quarter 1988. Report 758.

ERIC Educational Resources Information Center

Bureau of Labor Statistics (DOL), Washington, DC.

The female share of the older work force has nearly doubled since 1950. In 1987, the 6.2 million women aged 55 and over in the labor force constituted 4 of every 10 older workers. Because young women today have a stronger work attachment than did their mothers and grandmothers, the female share of the older work force is likely to continue to…

External Hand Forces Exerted by Long-Term Care Staff to Push Floor-Based Lifts: Effects of Flooring System and Resident Weight.

PubMed

Lachance, Chantelle C; Korall, Alexandra M B; Russell, Colin M; Feldman, Fabio; Robinovitch, Stephen N; Mackey, Dawn C

2016-09-01

The aim of this study was to investigate the effects of flooring type and resident weight on external hand forces required to push floor-based lifts in long-term care (LTC). Novel compliant flooring is designed to reduce fall-related injuries among LTC residents but may increase forces required for staff to perform pushing tasks. A motorized lift may offset the effect of flooring on push forces. Fourteen female LTC staff performed straight-line pushes with two floor-based lifts (conventional, motor driven) loaded with passengers of average and 90th-percentile resident weights over four flooring systems (concrete+vinyl, compliant+vinyl, concrete+carpet, compliant+carpet). Initial and sustained push forces were measured by a handlebar-mounted triaxial load cell and compared to participant-specific tolerance limits. Participants rated pushing difficulty. Novel compliant flooring increased initial and sustained push forces and subjective ratings compared to concrete flooring. Compared to the conventional lift, the motor-driven lift substantially reduced initial and sustained push forces and perceived difficulty of pushing for all four floors and both resident weights. Participants exerted forces above published tolerance limits only when using the conventional lift on the carpet conditions (concrete+carpet, compliant+carpet). With the motor-driven lift only, resident weight did not affect push forces. Novel compliant flooring increased linear push forces generated by LTC staff using floor-based lifts, but forces did not exceed tolerance limits when pushing over compliant+vinyl. The motor-driven lift substantially reduced push forces compared to the conventional lift. Results may help to address risk of work-related musculoskeletal injury, especially in locations with novel compliant flooring. © 2016, Human Factors and Ergonomics Society.

Development of electromagnetic welding facility of flat plates for nuclear industry

NASA Astrophysics Data System (ADS)

Kumar, Rajesh; Sahoo, Subhanarayan; Sarkar, Biswanath; Shyam, Anurag

2017-04-01

Electromagnetic pulse welding (EMPW) process, one of high speed welding process uses electromagnetic force from discharged current through working coil, which develops a repulsive force between the induced current flowing parallel and in opposite direction. For achieving the successful weldment using this process the design of working coil is the most important factor due to high magnetic field on surface of work piece. In case of high quality flat plate welding factors such as impact velocity, angle of impact standoff distance, thickness of flyer and overlap length have to be chosen carefully. EMPW has wide applications in nuclear industry, automotive industry, aerospace, electrical industries. However formability and weldability still remain major issues. Due to ease in controlling the magnetic field enveloped inside tubes, the EMPW has been widely used for tube welding. In case of flat components control of magnetic field is difficult. Hence the application of EMPW gets restricted. The present work attempts to make a novel contribution by investigating the effect of process parameters on welding quality of flat plates. The work emphasizes the approaches and engineering calculations required to effectively use of actuator in EMPW of flat components.

Wind-forced modulations in crossing sea states over infinite depth water

NASA Astrophysics Data System (ADS)

Debsarma, Suma; Senapati, Sudipta; Das, K. P.

2014-09-01

The present work is motivated by the work of Leblanc ["Amplification of nonlinear surface waves by wind," Phys. Fluids 19, 101705 (2007)] which showed that Stokes waves grow super exponentially under fair wind as a result of modulational instability. Here, we have studied the effect of wind in a situation of crossing sea states characterized by two obliquely propagating wave systems in deep water. It is found that the wind-forced uniform wave solution in crossing seas grows explosively with a super-exponential growth rate even under a steady horizontal wind flow. This is an important piece of information in the context of the formation of freak waves.

The Strategic Utility of U.S. Navy SEALs

DTIC Science & Technology

2009-06-01

USA Swimming, rugby organizations and wrestling organizations. In addition, while the demographics do not fully support it, the Navy and NSW put a...guerrilla 66 forces mainly against the Soviet Union (Waller, 1994). Recognizing the successes of the OSS and its ability to effectively work with...operations. This improved both forces capabilities and proved a very useful union . 78 SEALs are capable of this SFA mission, but it is a difficult

Vocational Qualifications for the UK Explosives Industry

DTIC Science & Technology

2010-07-15

Army, Royal Navy, Royal Air Force , Dstl, QinetiQ, AWE, Leafield Engineering and MBDA. ESA project outputs The key outcomes of the project were...specifically those who give fireworks displays or work as special effects technicians and armourers in film, TV and theatre and members of re-enactment...is scheduled to come into force in January 2011. We have developed “new style” QCF qualifications for two different communities: • those who

14 CFR 151.51 - Performance of construction work: Sponsor force account.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Performance of construction work: Sponsor force account. 151.51 Section 151.51 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT... Development Projects § 151.51 Performance of construction work: Sponsor force account. (a) Before undertaking...

14 CFR 151.51 - Performance of construction work: Sponsor force account.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Performance of construction work: Sponsor force account. 151.51 Section 151.51 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT... Development Projects § 151.51 Performance of construction work: Sponsor force account. (a) Before undertaking...

14 CFR 151.51 - Performance of construction work: Sponsor force account.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Performance of construction work: Sponsor force account. 151.51 Section 151.51 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT... Development Projects § 151.51 Performance of construction work: Sponsor force account. (a) Before undertaking...

14 CFR 151.51 - Performance of construction work: Sponsor force account.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Performance of construction work: Sponsor force account. 151.51 Section 151.51 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT... Development Projects § 151.51 Performance of construction work: Sponsor force account. (a) Before undertaking...

14 CFR 151.51 - Performance of construction work: Sponsor force account.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Performance of construction work: Sponsor force account. 151.51 Section 151.51 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT... Development Projects § 151.51 Performance of construction work: Sponsor force account. (a) Before undertaking...

Honeywell's Working Parents Task Force. Final Report and Recommendations.

ERIC Educational Resources Information Center

Honeywell, Inc., Minneapolis, Minn.

This publication provides a summary of the Honeywell Working Parent Task Force's recommendations on how to solve problems experienced by working parents. The Task Force consisted of three committees: the Employment Practices Committee (EPC); the Parent Education Committee (PEC); and the Child Care Facilities Committee (CCFC). After examining a…

Workforce Education: Issues for the New Century.

ERIC Educational Resources Information Center

Pautler, Albert J., Jr.

This paper is intended to guide small groups of vocational educators in discussions regarding work force education issues for the next century. The following work force issues are suggested: the aging work force; vocational education's role in reforming K-12 education; distance education for technical education programs; the labor shortages…

78 FR 67132 - GPS Satellite Simulator Control Working Group Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-08

... DEPARTMENT OF DEFENSE Department of the Air Force GPS Satellite Simulator Control Working Group Meeting AGENCY: Space and Missile Systems Center, Global Positioning Systems (GPS) Directorate, Air Force... Control Working Group (SSCWG) meeting on 6 December 2013 from 0900-1300 PST at Los Angeles Air Force Base...

Effect of Electrodynamic Forces on the Attitude Stabilization of a Satellite in Ecliptic orbits

NASA Astrophysics Data System (ADS)

Abdel-Aziz, Yehia

This work is based on the previous paper of the author [1]. The present paper is devoted to the investigation of the attitude dynamics of an ecliptic satellite moving in the magnetic field of the Earth. Eelectrodynamic forces result from the motion of a charged satelite relative to the magnetic field of the Earth. The torque due to electrodynamic effect of the Lorentz forces on the attitude stabilization of the satellite is studied with the detailed model of the Earth's magnetic field. A method for estimating the stable and unstable regions of the equilibrium positions based on Euler's equation is also discussed. The results show that Lorentz forces can affect the stablization of the satellite, in particular for highly eccentric orbits and also for large satellte. [1] Abdel-Aziz, Y. A. Attitude Stabilization of a Rigid Spacecraft in the Geomagnetic Field. AdSpR 40, 18-24, 2007.

Piezo-Electrochemical Energy Harvesting with Lithium-Intercalating Carbon Fibers.

PubMed

Jacques, Eric; Lindbergh, Göran; Zenkert, Dan; Leijonmarck, Simon; Kjell, Maria Hellqvist

2015-07-01

The mechanical and electrochemical properties are coupled through a piezo-electrochemical effect in Li-intercalated carbon fibers. It is demonstrated that this piezo-electrochemical effect makes it possible to harvest electrical energy from mechanical work. Continuous polyacrylonitrile-based carbon fibers that can work both as electrodes for Li-ion batteries and structural reinforcement for composites materials are used in this study. Applying a tensile force to carbon fiber bundles used as Li-intercalating electrodes results in a response of the electrode potential of a few millivolts which allows, at low current densities, lithiation at higher electrode potential than delithiation. More electrical energy is thereby released from the cell at discharge than provided at charge, harvesting energy from the mechanical work of the applied force. The measured harvested specific electrical power is in the order of 1 μW/g for current densities in the order of 1 mA/g, but this has a potential of being increased significantly.

Vapor bridges between solid substrates in the presence of the contact line pinning effect: Stability and capillary force

NASA Astrophysics Data System (ADS)

Liu, Yawei; Zhang, Xianren

2016-12-01

In this work, we focus on investigating how nanobubbles mediate long-range interaction between neighboring solid substrates in the presence of the contact line pinning effect caused by surface heterogeneities. Using the constrained lattice density functional theory (LDFT), we prove that the nanobubbles, which take the form of vapor bridges here, are stabilized by the pinning effect if the separation between two substrates is less than a critical distance. The critical distance strongly depends on the chemical potential (i.e., the degree of saturation) and could become extremely long at a special chemical potential. Moreover, under the pinning effect, the substrate chemistry only determines the stability of the vapor bridges and the range of the capillary force, but has less influences on the magnitude of the capillary force, indicating that the substrate chemistry or the apparent contact angle for droplets or bubbles on the substrates is no longer a direct parameter to determine the magnitude of capillary force. A qualitative analysis for the two dimensional vapor bridges by considering the feedback mechanism can explain the results from the LDFT calculations.

Survey of Beamed Energy Propulsion Concepts by the MSFC Space Environmental Effects Team

NASA Technical Reports Server (NTRS)

Gray, P. A.; Nehls, M. K.; Edwards, D. L.; Carruth, M. R., Jr.; Munafo, Paul M. (Technical Monitor)

2002-01-01

This will be a survey paper of work that was performed by the Space Environmental Effects Team at NASA's Marshall Space Flight Center in the area of laser energy propulsion concepts. Two types of laser energy propulsion techniques were investigated. The first was ablative propulsion, which used a pulsed ruby laser impacting on single layer coatings and films. The purpose of this investigation was to determine the laser power density that produced an optimum coupling coefficient for each type of material tested. A commercial off-the-shelf multi-layer film was also investigated for possible applications in ablative micro-thrusters, and its optimum coupling coefficient was determined. The second type of study measured the purely photonic force provided by a 300W CW YAG laser. In initial studies, the photon force resulting from the momentum of incident photons was measured directly using a vacuum compatible microbalance and these results were compared to theory. Follow-on work used the same CW laser to excite a stable optical cavity for the purpose of amplifying the available force from incident photons.

Experimental research on anchoring force in intestine for the motion of capsule robot.

PubMed

Chen, Wenwen; Ke, Quan; He, Shu; Luo, Weijie; Ji, Xing Chun; Yan, Guozheng

2013-07-01

Multiple research groups are currently attempting to develop less-invasive robotic capsule endoscopes (RCEs) with better outcomes for enteroscopic procedures. Understanding the biomechanical response of the bowel to RCE is crucial for optimizing the design of these devices. For this reason, this study aims to develop an analytical model to predict the anchoring force of the model when travelling through the intestine. Previous work has developed, characterized and tested the frictional characteristics of the intestine with microgroove structures that had different surface contours. This work tested basic anchoring force characteristics with custom-built testers and clamping mechanism dummies to analyse the robot clamping movement (which is vital to improving movement efficiency). Balloon-shaped and leg-based clamping mechanisms were developed, which were found to have variable anchoring forces from 0.01 N to 1.2 N. After analysing the experimental results it was found that: (a) robot weight does not play a major role in anchoring force; (b) an increase in anchoring force corresponded to an increase in diameter of the clamping mechanism; and (c) textured contact surfaces effectively increased friction. These results could be explained by the biomechanical response of the intestine, friction and mucoadhesion characteristics of the small intestine material. With these factors considered, a model was developed for determining anchoring force in the small intestine.

Health and Occupational Outcomes Among Injured, Nonstandard Shift Workers.

PubMed

Wong, Imelda S; Smith, Peter M; Mustard, Cameron A; Gignac, Monique A M

2015-11-01

This study compares health and occupational outcomes following a work-related injury for nonstandard and day-shift workers. National Population Health Survey data were used to explore outcomes 2 years post-work injury. Retrospective-matched cohort analyses examined main effects and interactions of shift schedule and work injury with changes in health, shift schedule, and labor force status. Models were adjusted for respondent characteristics, baseline health status, and occupational strength requirements. Injured nonstandard shift workers reported lower health utility index scores, compared with uninjured and injured daytime workers and uninjured nonstandard-shift workers. No significant interactions between shift and injury were found with schedule change and leaving the labor force. Injured nonstandard-shift workers are as likely to remain employed as other groups, but may be vulnerable in terms of diminished health.

Gaining Control of Occupational Injury and Illness in the U.S. Navy Civilian Work Force

DTIC Science & Technology

1990-01-16

caring for the back. Also monitored by the supervisor is a work -hardening program developed by the clinic physical therapist and physician that... development of a work -hardening program for the returning injured employee to ensure a safe re-entry to the workplace. e. "Green Table" and Medical...physical therapist work closely in developing effective programs for the treatment of occupational injuries. Having an onsite physical therapist available

The participation of women in the labour force of Latin America: fertility and other factors.

PubMed

Elizaga, J C

1974-01-01

The level of labor force participation among Latin American women, when compared with participation rates for other countries, is the lowest in the world. Only 20% or less of women 10 years of age and older are economically active. This level did not change much between 1950 and 1970. Few women work in agriculture. The following factors are considered for their effect on labor force participation of urban women: marital status, education, income, and the structure and stage of development of the society. Married women have a low participation rate. More highly educated women are more likely to work, but there must be demand for their work services. As the economy of various countries has progressed, female participation in domestic services has decreased, in industry has remained constant between 1960 and 1970, and in social services has expanded. It is concluded that work participation for married women will only increase with the following changes: 1) improved educational opportunities for women; 2) structural change and modernization in the economy; and 3) reduced family fertility. Changes in the first 2 factors are more important than reduced fertility. Since 1960, only Chile and Costa Rica have had a 25% decline in fertility rates.

Towards a Learning Workforce: A Policy Discussion Paper on Adult Learners at Work.

ERIC Educational Resources Information Center

Tuckett, Alan

There is widespread agreement in Great Britain that the work force must receive more skills training if the country is to be competitive in the future. Of special concern is the 70 percent of the work force who left school at the earliest possible opportunity, and the (overlapping) 70 percent of the work force who have not received training for a…

Calculation of electromagnetic force in electromagnetic forming process of metal sheet

NASA Astrophysics Data System (ADS)

Xu, Da; Liu, Xuesong; Fang, Kun; Fang, Hongyuan

2010-06-01

Electromagnetic forming (EMF) is a forming process that relies on the inductive electromagnetic force to deform metallic workpiece at high speed. Calculation of the electromagnetic force is essential to understand the EMF process. However, accurate calculation requires complex numerical solution, in which the coupling between the electromagnetic process and the deformation of workpiece needs be considered. In this paper, an appropriate formula has been developed to calculate the electromagnetic force in metal work-piece in the sheet EMF process. The effects of the geometric size of coil, the material properties, and the parameters of discharge circuit on electromagnetic force are taken into consideration. Through the formula, the electromagnetic force at different time and in different positions of the workpiece can be predicted. The calculated electromagnetic force and magnetic field are in good agreement with the numerical and experimental results. The accurate prediction of the electromagnetic force provides an insight into the physical process of the EMF and a powerful tool to design optimum EMF systems.

Correlation of Descriptive Analysis and Instrumental Puncture Testing of Watermelon Cultivars.

PubMed

Shiu, J W; Slaughter, D C; Boyden, L E; Barrett, D M

2016-06-01

The textural properties of 5 seedless watermelon cultivars were assessed by descriptive analysis and the standard puncture test using a hollow probe with increased shearing properties. The use of descriptive analysis methodology was an effective means of quantifying watermelon sensory texture profiles for characterizing specific cultivars' characteristics. Of the 10 cultivars screened, 71% of the variation in the sensory attributes was measured using the 1st 2 principal components. Pairwise correlation of the hollow puncture probe and sensory parameters determined that initial slope, maximum force, and work after maximum force measurements all correlated well to the sensory attributes crisp and firm. These findings confirm that maximum force correlates well with not only firmness in watermelon, but crispness as well. The initial slope parameter also captures the sensory crispness of watermelon, but is not as practical to measure in the field as maximum force. The work after maximum force parameter is thought to reflect cellular arrangement and membrane integrity that in turn impact sensory firmness and crispness. Watermelon cultivar types were correctly predicted by puncture test measurements in heart tissue 87% of the time, although descriptive analysis was correct 54% of the time. © 2016 Institute of Food Technologists®

Big Hat, No Cattle: Managing Human Resources, Part 1.

ERIC Educational Resources Information Center

Skinner, Wickham

1982-01-01

Presents an in-depth analysis of problems and a suggested approach to developing human resources which goes beyond identifying symptoms and provides a comprehensive perspective for building an effective work force. (JOW)

Aerodynamic forces and flow structures of the leading edge vortex on a flapping wing considering ground effect.

PubMed

Van Truong, Tien; Byun, Doyoung; Kim, Min Jun; Yoon, Kwang Joon; Park, Hoon Cheol

2013-09-01

The aim of this work is to provide an insight into the aerodynamic performance of the beetle during takeoff, which has been estimated in previous investigations. We employed a scaled-up electromechanical model flapping wing to measure the aerodynamic forces and the three-dimensional flow structures on the flapping wing. The ground effect on the unsteady forces and flow structures were also characterized. The dynamically scaled wing model could replicate the general stroke pattern of the beetle's hind wing kinematics during takeoff flight. Two wing kinematic models have been studied to examine the influences of wing kinematics on unsteady aerodynamic forces. In the first model, the angle of attack is asymmetric and varies during the translational motion, which is the flapping motion of the beetle's hind wing. In the second model, the angle of attack is constant during the translational motion. The instantaneous aerodynamic forces were measured for four strokes during the beetle's takeoff by the force sensor attached at the wing base. Flow visualization provided a general picture of the evolution of the three-dimensional leading edge vortex (LEV) on the beetle hind wing model. The LEV is stable during each stroke, and increases radically from the root to the tip, forming a leading-edge spiral vortex. The force measurement results show that the vertical force generated by the hind wing is large enough to lift the beetle. For the beetle hind wing kinematics, the total vertical force production increases 18.4% and 8.6% for the first and second strokes, respectively, due to the ground effect. However, for the model with a constant angle of attack during translation, the vertical force is reduced during the first stroke. During the third and fourth strokes, the ground effect is negligible for both wing kinematic patterns. This finding suggests that the beetle's flapping mechanism induces a ground effect that can efficiently lift its body from the ground during takeoff.

Sensorimotor adaptation to inertial forces in a multi-force environment does not depend on the number of targets: indirect validation of the altered-proprioception hypothesis.

PubMed

Bourdin, C; Bock, O

2006-11-20

The ability of our sensorimotor system to adapt to changing and complex environmental demands has been under experimental scrutiny for more than a century. Previous works have shown that aimed arm movements adapt quickly and completely to Coriolis force, but incompletely to the combination of Coriolis and centrifugal forces without visual cues. Two hypotheses may be advanced to explain this discrepancy: the workspace-exploration hypothesis, and the degraded-proprioception hypothesis. The aim of this study was to distinguish between the above two alternatives by comparing adaptive improvement during off-axis rotation in subjects pointing at one, three or seven different targets in complete darkness. Two main results emerge: (a) off-axis rotation led initially to errors in the direction of Coriolis force and in the opposite direction of the centrifugal force; (b) the size of the visited workspace has no effect on the way the subjects adapt to a multi-force environment. The lack of a target-number effect and the persistence of lateral errors in the pointing movements performed during rotation of the platform, support the degraded-proprioception rather than the workspace-exploration hypothesis of adaptation to a multi-force environment.

Soviet fertility, labor-force participation, and marital stability.

PubMed

Kuniansky, A

1983-06-01

A simultaneous-equations model of Soviet fertility and labor-force participation is estimated from a cross section of 72 oblast's of the Russian Republic (RSFSR) reported in the 1970 census. The construction of the model is based on the neoclassical theory of household behavior. Simulated changes capture effects of policy changes in the exogenous variables on Soviet fertility and the female labor supply. The exogenous variables investigated are child care facilities (CC), urbanization ratio (URB), male education (MALED), and female education (FEMED). It was found that an increase in FEMED affects labor force participation (LFP) directly and indirectly through impact on birth rate (BR). Increase in CC raise both LFP and BR; increases in FEMED causes womens withdrawal from the labor force and one would expect this to raise BR; however, FEMED raises the opportunity costs of fertility sufficiently to neutralize this effect. Increasing urbanization does not affect participation in a significant way, but it does retard fertility. This effect works through LFP's impact on BR and the indirect effect working through marital stability. A final set of simulations captured the impact of upward shocks of LFP, BR, and the ratio of divorces to marriages (DIV/MAR) on the endogenous variables. Such changes could occur through changes in abortion laws, tightening of divorce laws, or changes in labor legislation. Participation is reduced by the fertility shock, just as fertility is retarded by the LPF and marital stability shocks. Evidence of a backward-bending labor-supply curve was also found. The model is illustrated by tables and charts.

Patellar tendon load in different types of eccentric squats.

PubMed

Frohm, A; Halvorsen, K; Thorstensson, A

2007-07-01

Differences in mechanical loading of the patellar tendon have been suggested as a reason for varying effects in rehabilitation of patellar tendinopathy using different eccentric squat exercises and devices. The aim was to characterize the magnitude and pattern of mechanical load at the knee and on the patellar tendon during four types of eccentric squat. Subjects performed squats with a submaximal free weight and with maximal effort in a device for eccentric overloading (Bromsman), on a decline board and horizontal surface. Kinematics was recorded with a motion-capture system, reaction forces with force plates, and electromyography from three leg muscles with surface electrodes. Inverse dynamics was used to calculate knee joint kinetics. Eccentric work, mean and peak patellar tendon force, and angle at peak force were greater (25-30%) for squats on decline board compared to horizontal surface with free weight, but not in Bromsman. Higher knee load forces (60-80%), but not work, were observed with Bromsman than free weight. Angular excursions at the knee and ankle were larger with decline board, particularly with free weight, and smaller in Bromsman than with free weight. Mean electromyography was greater on a decline board for gastrocnemius (13%) and vastus medialis (6%) with free weight, but in Bromsman only for gastrocnemius (7%). The results demonstrated clear differences in the biomechanical loading on the knee during different squat exercises. Quantification of such differences provides information that could be used to explain differences in rehabilitation effects as well as in designing more optimal rehabilitation exercises for patellar tendinopathy.

Exploring the effects of dimensionality reduction in deep networks for force estimation in robotic-assisted surgery

NASA Astrophysics Data System (ADS)

Aviles, Angelica I.; Alsaleh, Samar; Sobrevilla, Pilar; Casals, Alicia

2016-03-01

Robotic-Assisted Surgery approach overcomes the limitations of the traditional laparoscopic and open surgeries. However, one of its major limitations is the lack of force feedback. Since there is no direct interaction between the surgeon and the tissue, there is no way of knowing how much force the surgeon is applying which can result in irreversible injuries. The use of force sensors is not practical since they impose different constraints. Thus, we make use of a neuro-visual approach to estimate the applied forces, in which the 3D shape recovery together with the geometry of motion are used as input to a deep network based on LSTM-RNN architecture. When deep networks are used in real time, pre-processing of data is a key factor to reduce complexity and improve the network performance. A common pre-processing step is dimensionality reduction which attempts to eliminate redundant and insignificant information by selecting a subset of relevant features to use in model construction. In this work, we show the effects of dimensionality reduction in a real-time application: estimating the applied force in Robotic-Assisted Surgeries. According to the results, we demonstrated positive effects of doing dimensionality reduction on deep networks including: faster training, improved network performance, and overfitting prevention. We also show a significant accuracy improvement, ranging from about 33% to 86%, over existing approaches related to force estimation.

The Changing Work Force. Trends and Issues Alerts.

ERIC Educational Resources Information Center

Lankard, Bettina A.

Economic pressures, work force diversity, and advances in technology are changing the nature of work and organizational policy and management. A predicted decline in the annual growth in gross national product is expected to trigger a slowdown in the labor force, especially in occupations that employ workers with only a high school education.…

[Fact Sheets on Working Women].

ERIC Educational Resources Information Center

National Commission on Working Women, Washington, DC.

These four fact sheets address a number of issues relating to women in the work force. The first, "An Overview of Women in the Work Force," offers a look at the numbers of women in the labor force, the occupational categories represented by women workers, women in professional and nonprofessional occupations, and women in nontraditional…

America's Changing Work Force. Statistics in Brief.

ERIC Educational Resources Information Center

American Association of Retired Persons, Washington, DC.

This booklet provides information about the changing work force. It offers a profile of workers aged 45 and older, as well as likely changes in the work force of the future. Tables and graphs illustrate the following: profile of Americans aged 50 and older, by employment status; employment status of the civilian noninstitutional population by age…

Extracting the driving force from ozone data using slow feature analysis

NASA Astrophysics Data System (ADS)

Wang, Geli; Yang, Peicai; Zhou, Xiuji

2016-05-01

Slow feature analysis (SFA) is a recommended technique for extracting slowly varying features from a quickly varying signal. In this work, we apply SFA to total ozone data from Arosa, Switzerland. The results show that the signal of volcanic eruptions can be found in the driving force, and wavelet analysis of this driving force shows that there are two main dominant scales, which may be connected with the effect of climate mode such as North Atlantic Oscillation (NAO) and solar activity. The findings of this study represent a contribution to our understanding of the causality from observed climate data.

Widowhood, sex, labor force participation, and the use of physician services by elderly adults.

PubMed

Homan, S M; Haddock, C C; Winner, C A; Coe, R M; Wolinsky, F D

1986-11-01

This paper investigated the relationships of widowhood, sex, and labor force participation with the use of ambulatory physician services by elderly adults. Data on 18,441 individuals aged 55 and over were taken from the 1978 Health Interview Survey. Hierarchical regression results indicated that although these three factors are related to physician utilization at the zero- and first-partial levels, only sex remained significant when their two- and three-way interactions and other variables from the behavioral model (including living arrangements) were introduced. This suggests that the effects of widowhood and labor force participation are spurious. Widows are simply more likely to live alone and are less likely to work than widowers; those who live alone and do not work are more likely to use health services (and more of them) than those who live with others and are gainfully employed.

You Can't Get There from Here: Working Women and the Glass Ceiling.

ERIC Educational Resources Information Center

Business and Professional Women's Foundation, Washington, DC.

Over the past two decades women and minorities have made unprecedented strides into the work force, yet discrimination due to gender and race is still a problem. The dearth of women in management is due to the "glass ceiling" phenomenon--the organizational, attitudinal, and societal barriers that effectively keep women and minorities…

The effects of central pro-and anti-inflammatory immune challenges on depressive-like behavior induced by chronic forced swim stress in rats.

PubMed

Pan, Yuqin; Lin, Wenjuan; Wang, Weiwen; Qi, Xiaoli; Wang, Donglin; Tang, Mingming

2013-06-15

Although increasing evidence demonstrates that both chronic stressors and inflammatory immune activation contribute to pathophysiology and behavioral alterations associated with major depression, little is known about the interaction effect of central inflammatory immune activation and stress on depressive-like behavior. Our previous work has shown that 14-day chronic forced swim stress induces significant depressive-like behavior. The present investigation assessed whether pro-inflammatory cytokine and anti-inflammatory cytokine challenges have differential interaction effect on depressive-like behavior induced by chronic forced swim stress in rats. The pro-inflammatory and anti-inflammatory immune challenges were achieved respectively by central administration of lipopolysaccharide (LPS), a pro-inflammatory cytokine inducer, and interleukin-10 (IL-10), an anti-inflammatory cytokine. It was found that either central LPS treatment alone or chronic forced swim stress alone significantly induced depressive-like behavior, including reduced body weight gain, reduced saccharin preference and reduced locomotor activity. However, there was no significant synergistic or additive effect of central LPS treatment and stress on depressive-like behavior. LPS treatment did not exacerbate the depressive-like behavior induced by forced swim stress. Nevertheless, IL-10 reversed depressive-like behavior induced by forced swim stress, a finding indicating that IL-10 has antidepressant effect on behavioral depression induced by stress. The present findings provide new insight into the complexity of the immunity-inflammation hypothesis of depression. Copyright © 2013 Elsevier B.V. All rights reserved.

The impact of working technique on physical loads - an exposure profile among newspaper editors.

PubMed

Lindegård, A; Wahlström, J; Hagberg, M; Hansson, G-A; Jonsson, P; Wigaeus Tornqvist, E

2003-05-15

The aim of this study was to investigate the possible associations between working technique, sex, symptoms and level of physical load in VDU-work. A study group of 32 employees in the editing department of a daily newspaper answered a questionnaire, about physical working conditions and symptoms from the neck and the upper extremities. Muscular load, wrist positions and computer mouse forces were measured. Working technique was assessed from an observation protocol for computer work. In addition ratings of perceived exertion and overall comfort were collected. The results showed that subjects classified as having a good working technique worked with less muscular load in the forearm (extensor carpi ulnaris p=0.03) and in the trapezius muscle on the mouse operating side (p=0.02) compared to subjects classified as having a poor working technique. Moreover there were no differences in gap frequency (number of episodes when muscle activity is below 2.5% of a reference contraction) or muscular rest (total duration of gaps) between the two working technique groups. Women in this study used more force (mean force p=0.006, peak force p=0.02) expressed as % MVC than the men when operating the computer mouse. No major differences were shown in muscular load, wrist postures, perceived exertion or perceived comfort between men and women or between cases and symptom free subjects. In conclusion a good working technique was associated with reduced muscular load in the forearm muscles and in the trapezius muscle on the mouse operating side. Moreover women used more force (mean force and peak force) than men when operating the click button (left button) of the computer mouse.

Defining Conditions for the Use of Persistent Surveillance

DTIC Science & Technology

2009-12-01

as hard as the Air Force has worked the North Dakota and Ohio delegations,’ says Colonel Charles Bartlett, head of a special Air Force task force on...UAVs…While Richard Shelby , the Republican senator from Alabama, is concerned about the impact on Redstone Arsenal, which manages much of the Army’s...UAV work, Byron Dorgan, the North Dakota Democratic senator, wants to attract more work for Grand Forks Air Force base, partly to make up for the

A Global View on the Effects of Work on Health in Later Life.

PubMed

Staudinger, Ursula M; Finkelstein, Ruth; Calvo, Esteban; Sivaramakrishnan, Kavita

2016-04-01

Work is an important environment shaping the aging processes during the adult years. Therefore, the cumulative and acute effects of work characteristics on late-life health deserve great attention. Given that population aging has become a global trend with ensuing changes in labor markets around the world, increased attention is paid to investigating the effects of the timing of retirement around the world and the macroeconomic benefits often associated with delaying retirement. It will be essential for societies with aging populations to maintain productivity given an aging workforce and for individuals it will be crucial to add healthy and meaningful years rather than just years to their lives. We first describe the available evidence about participation of older workers (65+) in the labor force in high, middle, and low-income countries. Second, we discuss the individual-level and societal influences that might govern labor-force participation of older adults. Thirdly, we review evidence on the association between work on the one and physical, mental, and cognitive health in later life on the other. Globally, both is true: work supports healthy aging and jeopordizes it. We draw implications for policymaking in terms of social protection, HR policies, and older employee employability. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Research on the parallel load sharing principle of a novel self-decoupled piezoelectric six-dimensional force sensor.

PubMed

Li, Ying-Jun; Yang, Cong; Wang, Gui-Cong; Zhang, Hui; Cui, Huan-Yong; Zhang, Yong-Liang

2017-09-01

This paper presents a novel integrated piezoelectric six-dimensional force sensor which can realize dynamic measurement of multi-dimensional space load. Firstly, the composition of the sensor, the spatial layout of force-sensitive components, and measurement principle are analyzed and designed. There is no interference of piezoelectric six-dimensional force sensor in theoretical analysis. Based on the principle of actual work and deformation compatibility coherence, this paper deduces the parallel load sharing principle of the piezoelectric six-dimensional force sensor. The main effect factors which affect the load sharing ratio are obtained. The finite element model of the piezoelectric six-dimensional force sensor is established. In order to verify the load sharing principle of the sensor, a load sharing test device of piezoelectric force sensor is designed and fabricated. The load sharing experimental platform is set up. The experimental results are in accordance with the theoretical analysis and simulation results. The experiments show that the multi-dimensional and heavy force measurement can be realized by the parallel arrangement of the load sharing ring and the force sensitive element in the novel integrated piezoelectric six-dimensional force sensor. The ideal load sharing effect of the sensor can be achieved by appropriate size parameters. This paper has an important guide for the design of the force measuring device according to the load sharing mode. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Unsteady swimming of small organisms

NASA Astrophysics Data System (ADS)

Wang, Shiyan; Ardekani, Arezoo

2012-11-01

Small planktonic organisms ubiquitously display unsteady or impulsive motion to attack a prey or escape a predator in natural environments. Despite this, the role of unsteady hydrodynamic forces such as history and added mass forces on the low Reynolds number propulsion of small organisms is poorly understood. In this paper, we derive the fundamental equation of motion for an organism swimming by the means of surface distortion in a nonuniform flow at a low Reynolds number regime. We show that the history and added mass forces, that where traditionally neglected in the literature for small swimming organisms, cannot be neglected as the Stokes number increases above unity. For example, these unsteady inertial forces are of the same order as quasi-steady Stokes forces for Paramecium. Finally, we quantify the effects of convective inertial forces in the limit of small, but nonzero, Reynolds number regime. This work is supported by NSF grant CBET-1066545.

11th Annual Systems Engineering Conference

DTIC Science & Technology

2008-10-23

effectiveness for force structure architecture studies – Problem of interest was Layered Intelligence, Surveillance and Reconnaissance ( LISR ) with Integrated...Cleared for Public Release, Control No. 08-110, dtd. 10-1-0811 LISR CET Typical Products 1 Satellite_A; 1 Satellite_B; 3 VehA; 1 VehB (50%) 2 VehA; 3...the means to support LISR force structure architecture studies: Stand-alone and as a lead-in to detailed work Cleared for Public Release, Control No

Switched capacitor charge pump used for low-distortion imaging in atomic force microscope.

PubMed

Zhang, Jie; Zhang, Lian Sheng; Feng, Zhi Hua

2015-01-01

The switched capacitor charge pump (SCCP) is an effective method of linearizing charges on piezoelectric actuators and therefore constitute a significant approach to nano-positioning. In this work, it was for the first time implemented in an atomic force microscope for low-distortion imaging. Experimental results showed that the image quality was improved evidently under the SCCP drive compared with that under traditional linear voltage drive. © Wiley Periodicals, Inc.

A model of involvement in work-related learning and development activity: the effects of individual, situational, motivational, and age variables.

PubMed

Maurer, Todd J; Weiss, Elizabeth M; Barbeite, Francisco G

2003-08-01

Eight hundred employees from across the U.S. work force participated in a detailed 13-month longitudinal study of involvement in learning and development activities. A new model was posited and tested in which the hypothesized sequence was as follows: worker age --> individual and situational antecedents --> perceived benefits of participation and self-efficacy for development --> attitudes toward development --> intentions to participate --> participation. The results depict a person who is oriented toward employee development as having participated in development activities before, perceiving themselves as possessing qualities needed for learning, having social support for development at work and outside of work, being job involved, having insight into his or her career, and believing in the need for development, in his or her ability to develop skills and to receive intrinsic benefits from participating. Given the aging work force, a detailed treatment of age differences in development is presented. Implications for new ideas in practice and future research are discussed.

Statistics of work performed on a forced quantum oscillator.

PubMed

Talkner, Peter; Burada, P Sekhar; Hänggi, Peter

2008-07-01

Various aspects of the statistics of work performed by an external classical force on a quantum mechanical system are elucidated for a driven harmonic oscillator. In this special case two parameters are introduced that are sufficient to completely characterize the force protocol. Explicit results for the characteristic function of work and the corresponding probability distribution are provided and discussed for three different types of initial states of the oscillator: microcanonical, canonical, and coherent states. Depending on the choice of the initial state the probability distributions of the performed work may greatly differ. This result in particular also holds true for identical force protocols. General fluctuation and work theorems holding for microcanonical and canonical initial states are confirmed.

Mitigated-force carriage for high magnetic field environments

DOEpatents

Ludtka, Gerard M.; Ludtka, Gail M.; Wilgen, John B.; Murphy, Bart L.

2015-05-19

A carriage for high magnetic field environments includes a plurality of work-piece separators disposed in an operable relationship with a work-piece processing magnet having a magnetic field strength of at least 1 Tesla for supporting and separating a plurality of work-pieces by a preselected, essentially equal spacing, so that, as a first work-piece is inserted into the magnetic field, a second work-piece is simultaneously withdrawn from the magnetic field, so that an attractive magnetic force imparted on the first work-piece offsets a resistive magnetic force imparted on the second work-piece.

DOD Civilian Personnel. Intelligence Personnel System Incorporates Safeguards, but Opportunities Exist for Improvement

DTIC Science & Technology

2009-12-01

high standards of integrity, conduct, and concern for the public interest. 5. The Federal work force should be used efficiently and effectively . 6...NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) U.S. Government Accountability Office,441 G Street...in its implementation of DCIPS, DOD has taken some positive steps to incorporate 10 internal safeguards to help ensure the fair, effective , and

Crouch gait can be an effective form of forced-use/no constraint exercise for the paretic lower limb in stroke.

PubMed

Tesio, Luigi; Rota, Viviana; Malloggi, Chiara; Brugliera, Luigia; Catino, Luigi

2017-09-01

In hemiplegic gait the paretic lower limb provides less muscle power and shows a briefer stance compared with the unaffected limb. Yet, a longer stance and a higher power can be obtained from the paretic lower limb if gait speed is increased. This supports the existence of a 'learned non-use' phenomenon, similar to that underlying some asymmetric impairments of the motion of the eyes and of the upper limbs. Crouch gait (CG) (bent-hip bent-knee, about 30° minimum knee flexion) might be an effective form of 'forced-use' treatment of the paretic lower limb. It is not known whether it also stimulates a more symmetric muscle power output. Gait analysis on a force treadmill was carried out in 12 healthy adults and seven hemiplegic patients (1-127 months after stroke, median: 1.6). Speed was imposed at 0.3 m/s. Step length and single and double stance times, sagittal joint rotations, peak positive power, and work in extension of the hip, knee, and ankle (plantar flexion), and surface electromyography (sEMG) area from extensor muscles during the generation of power were measured on either side during both erect and crouch walking. Significance was set at P less than 0.05; corrections for multiplicity were applied. Patients, compared with healthy controls, adopted in both gait modalities and on both sides a shorter step length (61-84%) as well as a shorter stance (76-90%) and swing (63-83%) time. As a rule, they also provided a higher muscular work (median: 137%, range: 77-250%) paralleled by a greater sEMG area (median: 174%, range: 75-185%). In erect gait, the generation of peak extensor power across hip, knee, and ankle joints was in general lower (83-90%) from the paretic limb and higher (98-165%) from the unaffected limb compared with control values. In CG, peak power generation across the three lower limb joints was invariably higher in hemiparetic patients: 107-177% from the paretic limb and 114-231% from the unaffected limb. When gait shifted from erect to crouch, only for hemiplegic patients, at the hip, the paretic/unaffected ratio increased significantly. For peak power, work, sEMG area, and joint rotation, the paretic/unaffected ratio increased from 55 to 85%, 56 to 72%, 68 to 91%, and 67 to 93%, respectively. CG appears to be an effective form of forced-use exercise eliciting more power and work from the paretic lower limb muscles sustained by a greater neural drive. It also seems effective in forcing a more symmetric power and work from the hip extensor muscles, but neither from the knee nor the ankle.

An Analysis of the Effects of Varying Male and Female Force Levels. Annex 5. Organizational Assessment Study,

DTIC Science & Technology

1985-03-01

respondent works on a daily basis toward a common mission. It typically contains under 20 people, working on the same shift, with the same functional...ppropriate sex roles for women in the Army. Enlisted males had ubstantially more negative attitudes towards women than either CO supervisors or officers...y respondents. For purposes of this study, the work group is defined as the group of people with whom the respondent works on a daily toward a common

The interrelation between mechanical characteristics of contracting muscle, cross-bridge internal structure, and the mechanism of chemomechanical energy transduction.

PubMed

Rosenfeld, E V

2012-09-01

The cross-bridge working stroke is regarded as a continuous (without jumps) change of myosin head internal state under the action of a force exerted within the nucleotide-binding site. Involvement of a concept of continuous cross-bridge conformation enables discussion of the nature of the force propelling muscle, and the Coulomb repulsion of like-charged adenosine triphosphate (ATP) fragments ADP(2-) and P (i) (2-) can quite naturally be considered as the source of this force. Two entirely different types of working stroke termination are considered. Along with the fluctuation mechanism, which controls the working stroke duration t (w) at isometric contraction, another interrupt mechanism is initially taken into account. It is triggered when the lever arm shift amounts to the maximal value S ≈ 11 nm, the back door opens, and P(i) crashes out. As a result, t (w) becomes inversely proportional to the velocity v of sliding filaments t (w) ≈ S/v for a wide range of values of v. Principal features of the experimentally observed dependences of force, efficiency, and rate of heat production on velocity and ATP concentration can then be reproduced by fitting a single parameter: the velocity-independent time span t (r) between the termination of the last and beginning of the next working stroke. v becomes the principal variable of the model, and the muscle force changes under external load are determined by variations in v rather than in the tension of filaments. The Boltzmann equation for an ensemble of cross-bridges is obtained, and some collective effects are discussed.

Some Labour Implications of Technological Change in Rail and Air Transport.

ERIC Educational Resources Information Center

Gil, Avishai

1986-01-01

Repercussions of recent economic difficulties on job content, employment levels, structure of the work force, and industrial relations are examined. The effect of new technologies on these areas is discussed. (Author/CT)

Attitude: A Component of Competent Performance.

ERIC Educational Resources Information Center

Meussling, Vonne

The findings of a survey of attitude studies to determine the effect of students' attitudes on communication competence as they enter the work force and develop their careers are reported in this paper. The paper explains how attitude improvement is an effective management tool in controlling costly absenteeism, output, job productivity, work…

Numerical and experimental analysis of the sedimentation of spherical colloidal suspensions under centrifugal force

NASA Astrophysics Data System (ADS)

Antonopoulou, Evangelia; Rohmann-Shaw, Connor F.; Sykes, Thomas C.; Cayre, Olivier J.; Hunter, Timothy N.; Jimack, Peter K.

2018-03-01

Understanding the sedimentation behaviour of colloidal suspensions is crucial in determining their stability. Since sedimentation rates are often very slow, centrifugation is used to expedite sedimentation experiments. The effect of centrifugal acceleration on sedimentation behaviour is not fully understood. Furthermore, in sedimentation models, interparticle interactions are usually omitted by using the hard-sphere assumption. This work proposes a one-dimensional model for sedimentation using an effective maximum volume fraction, with an extension for sedimentation under centrifugal force. A numerical implementation of the model using an adaptive finite difference solver is described. Experiments with silica suspensions are carried out using an analytical centrifuge. The model is shown to be a good fit with experimental data for 480 nm spherical silica, with the effects of centrifugation at 705 rpm studied. A conversion of data to Earth gravity conditions is proposed, which is shown to recover Earth gravity sedimentation rates well. This work suggests that the effective maximum volume fraction accurately captures interparticle interactions and provides insights into the effect of centrifugation on sedimentation.

The interactive effect of cooling and hypoxia on forearm fatigue development.

PubMed

Lloyd, Alex; Hodder, Simon; Havenith, George

2015-09-01

To examine the effect of separate and combined exposure to hypoxia [normoxia (FIO2 = 0.21) vs. moderate altitude (FIO2 = 0.13)] and temperature [thermoneutral (22 °C) vs. cold (5 °C)] on muscle fatigue development in the forearm, after repeated low-resistance contractions. Eight males were exposed for 70 min to four separate conditions in a balanced order. Conditions were normoxic-thermoneutral (N), hypoxic-thermoneutral, normoxic-cold and hypoxic-cold. After 15-min seated rest, participants carried out intermittent dynamic forearm exercise at 15 % maximal isometric voluntary contraction (MVC) for eight consecutive, 5-min work bouts. Each bout was separated by 110 s rest during which MVC force was collected. When exposed to hypoxia and cold independently, the exercise protocol decreased MVC force of the finger flexors by 8.1 and 13.9 %, respectively, compared to thermoneutral normoxia. When hypoxia and cold were combined, the decrease in MVC force was 21.4 % more than thermoneutral normoxia, reflecting an additive effect and no interaction. EMG relative to force produced during MVC, increased by 2 and 1.2 μV per kg (36 and 23 % of N) for cold and hypoxia, respectively. When the stressors were combined the effect was additive, increasing to 3.1 μV per kg (56 % of N). When compared to exercise in thermoneutral normoxic conditions, both cold and hypoxia significantly reduce brief MVC force output. This effect appears to be of mechanical origin, not a failure in muscle fibre recruitment per se. Additionally, the reduction in force is greater when the stressors are combined, showing an additive effect.

Gauge Physics of Spin Hall Effect

PubMed Central

Tan, Seng Ghee; Jalil, Mansoor B. A.; Ho, Cong Son; Siu, Zhuobin; Murakami, Shuichi

2015-01-01

Spin Hall effect (SHE) has been discussed in the context of Kubo formulation, geometric physics, spin orbit force, and numerous semi-classical treatments. It can be confusing if the different pictures have partial or overlapping claims of contribution to the SHE. In this article, we present a gauge-theoretic, time-momentum elucidation, which provides a general SHE equation of motion, that unifies under one theoretical framework, all contributions of SHE conductivity due to the kinetic, the spin orbit force (Yang-Mills), and the geometric (Murakami-Fujita) effects. Our work puts right an ambiguity surrounding previously partial treatments involving the Kubo, semiclassical, Berry curvatures, or the spin orbit force. Our full treatment shows the Rashba 2DEG SHE conductivity to be instead of −, and Rashba heavy hole instead of −. This renewed treatment suggests a need to re-derive and re-calculate previously studied SHE conductivity. PMID:26689260

Magnetic field effects on the vestibular system: calculation of the pressure on the cupula due to ionic current-induced Lorentz force

NASA Astrophysics Data System (ADS)

Antunes, A.; Glover, P. M.; Li, Y.; Mian, O. S.; Day, B. L.

2012-07-01

Large static magnetic fields may be employed in magnetic resonance imaging (MRI). At high magnetic field strengths (usually from about 3 T and above) it is possible for humans to perceive a number of effects. One such effect is mild vertigo. Recently, Roberts et al (2011 Current Biology 21 1635-40) proposed a Lorentz-force mechanism resulting from the ionic currents occurring naturally in the endolymph of the vestibular system. In the present work a more detailed calculation of the forces and resulting pressures in the vestibular system is carried out using a numerical model. Firstly, realistic 3D finite element conductivity and fluid maps of the utricle and a single semi-circular canal containing the current sources (dark cells) and sinks (hair cells) of the utricle and ampulla were constructed. Secondly, the electrical current densities in the fluid are calculated. Thirdly, the developed Lorentz force is used directly in the Navier-Stokes equation and the trans-cupular pressure is computed. Since the driving force field is relatively large in comparison with the advective acceleration, we demonstrate that it is possible to perform an approximation in the Navier-Stokes equations that reduces the problem to solving a simpler Poisson equation. This simplification allows rapid and easy calculation for many different directions of applied magnetic field. At 7 T a maximum cupula pressure difference of 1.6 mPa was calculated for the combined ampullar (0.7 µA) and utricular (3.31 µA) distributed current sources, assuming a hair-cell resting current of 100 pA per unit. These pressure values are up to an order of magnitude lower than those proposed by Roberts et al using a simplistic model and calculation, and are in good agreement with the estimated pressure values for nystagmus velocities in caloric experiments. This modeling work supports the hypothesis that the Lorentz force mechanism is a significant contributor to the perception of magnetic field induced vertigo.

Development of a laboratory test for knicker tearing re-creation studies.

PubMed

Carr, D J; Mitchell, J L; Niven, B E; Girvan, E; Carney, S

2016-05-01

False sexual assault and rape claims result in wasted forensic and police resources and stigma for the alleged offender. In this work a laboratory method was developed to (i) recreate the ripping of knickers and (ii) measure the force required to rip the garments. The effect of laundering was considered as a means to mimic age of garment, and the effect of speed of ripping was used as a measure of forcible removal of garments. Whilst laundering resulted in visual damage to the thongs, it did not affect the mechanical properties. Faster test speeds resulted in higher measured forces and increased levels of damage. This may allow comment to be made regarding the level of force used during an attack. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

An approach to human work systems development under the circumstances of an aging society and international business operations.

PubMed

Ikeda, Y T

1997-12-01

At least three serious aspects of problems exist as obstacles for the national economy in Japan to grow or even to maintain its present level: the lack of natural resources, the trends of a decreasing young labor force, and an increase in the shift of domestic business operations to foreign countries. Although top managers make the decisions of product or service planning, or both, work systems designers are also responsible for conserving the resources. An action against the decrease of the young work force is needed to maintain work systems in an operable condition. The business shifts to foreign countries affect all the people, who are losing job opportunities. The present paper presents an approach to reorienting human work systems within the scope of the work systems designers' roles under the circumstance of these social environments. The following discussion is based on the assumptions that work organizations be productive for themselves and the world, effective and efficient for themselves, and contributive to their communities and the world. In essence, an approach to human work systems development should be fair to managers and workers alike. Presented are cases of these work systems as developed along the perspectives mentioned.

Work in America: Implications for Families. Hearing before the Select Committee on Children, Youth, and Families. House of Representatives, Ninety-Ninth Congress, Second Session.

ERIC Educational Resources Information Center

Congress of the U.S., Washington, DC. House Select Committee on Children, Youth, and Families.

This hearing explored the value of work, and how changes in the economy and the composition of the work force have affected families. Witnesses (1) reported data on such topics as the kinds of jobs currently available, women's participation in the work force, unemployment, and labor force growth over the next decade; (2) argued that the economy is…

The President’s Identity Theft Task Force Report

DTIC Science & Technology

2008-09-01

effeCtIve, RISk-BASed ReSPOnSeS tO dAtA BReACheS SUffeRed By fedeRAl AGenCIeS Issue Data Breach Guidance to Agencies Publish a “Routine Use...and developing a data breach response plan. The FTC will continue to seek opportunities to work with state and local officials and policymakers...of fiscal year 2008. ReCOMMendAtIOn 4: enSURe effeCtIve, RISk-BASed ReSPOnSeS tO dAtA BReACheS SUffeRed By fedeRAl AGenCIeS The Task Force

Influence of various force fields in estimating the binding affinity of acetylcholinesterase inhibitors using fast pulling of ligand scheme

NASA Astrophysics Data System (ADS)

Tam, Nguyen Minh; Vu, Khanh B.; Vu, Van V.; Ngo, Son Tung

2018-06-01

Acetylcholinesterase (AChE) is considered as one of the most favored drug targets for Alzheimer's disease. The effects of different force fields (FFs) on ranking affinity of acetylcholinesterase inhibitors were obtained using the fast pulling of ligand (FPL) method in steered-molecular dynamics (SMD) simulations. GROMOS, AMBER, CHARMM, and OPLS-AA FFs were investigated in this work. The pulling work derived with GROMOS FF has the strongest correlation and smallest error compared with experimental binding affinity. Moreover, the CPU consumption in the calculations using GROMOS FF is the lowest, which could allow us to rank affinity of a large number of AChE ligands.

Research on parallel load sharing principle of piezoelectric six-dimensional heavy force/torque sensor

NASA Astrophysics Data System (ADS)

Liu, Wei; Li, Ying-jun; Jia, Zhen-yuan; Zhang, Jun; Qian, Min

2011-01-01

In working process of huge heavy-load manipulators, such as the free forging machine, hydraulic die-forging press, forging manipulator, heavy grasping manipulator, large displacement manipulator, measurement of six-dimensional heavy force/torque and real-time force feedback of the operation interface are basis to realize coordinate operation control and force compliance control. It is also an effective way to raise the control accuracy and achieve highly efficient manufacturing. Facing to solve dynamic measurement problem on six-dimensional time-varying heavy load in extremely manufacturing process, the novel principle of parallel load sharing on six-dimensional heavy force/torque is put forward. The measuring principle of six-dimensional force sensor is analyzed, and the spatial model is built and decoupled. The load sharing ratios are analyzed and calculated in vertical and horizontal directions. The mapping relationship between six-dimensional heavy force/torque value to be measured and output force value is built. The finite element model of parallel piezoelectric six-dimensional heavy force/torque sensor is set up, and its static characteristics are analyzed by ANSYS software. The main parameters, which affect load sharing ratio, are analyzed. The experiments for load sharing with different diameters of parallel axis are designed. The results show that the six-dimensional heavy force/torque sensor has good linearity. Non-linearity errors are less than 1%. The parallel axis makes good effect of load sharing. The larger the diameter is, the better the load sharing effect is. The results of experiments are in accordance with the FEM analysis. The sensor has advantages of large measuring range, good linearity, high inherent frequency, and high rigidity. It can be widely used in extreme environments for real-time accurate measurement of six-dimensional time-varying huge loads on manipulators.

Mitigated-force carriage for high magnetic field environments

DOEpatents

Ludtka, Gerard M; Ludtka, Gail M; Wilgen, John B; Murphy, Bart L

2014-05-20

A carriage for high magnetic field environments includes a first work-piece holding means for holding a first work-piece, the first work-piece holding means being disposed in an operable relationship with a work-piece processing magnet having a magnetic field strength of at least 1 Tesla. The first work-piece holding means is further disposed in operable connection with a second work-piece holding means for holding a second work-piece so that, as the first work-piece is inserted into the magnetic field, the second work-piece is simultaneously withdrawn from the magnetic field, so that an attractive magnetic force imparted on the first work-piece offsets a resistive magnetic force imparted on the second work-piece.

Fifty Indices of Effectiveness Regarding the Program Advisory Committees in Minnesota's Technical Colleges: A Working Paper. Effective Advisory Committees Project.

ERIC Educational Resources Information Center

Mercer, John W.; Meunier, Greg R.

This document, which was developed by a task force whose members represent the instructional, student support service, administrative, and executive ranks of technical colleges with very diverse sizes, locations, and programs, lists 50 proposed indices of effectiveness regarding the program advisory committees (ACs) in Minnesota's technical…

Design framework of a teleoperating system for a magnetically levitated robot with force feedback

NASA Astrophysics Data System (ADS)

Tsuda, Naoaki; Kato, Norihiko; Nomura, Yoshihiko; Matsui, Hirokazu

2002-02-01

Precise works and manipulating micro objects are tough jobs for operators both mentally and physically. To execute these jobs smoothly without feeling wrongness, use of master-slave system is preferable because position and force are able to be scaled up and down as well under the system. In this study we develop a master-slave system where the size of a slave robot is very small and the slave robot is levitated by magnetic forces. In distinction from ordinary master- slave systems, the levitated robot does not get any other contact forces from outside. Thus we introduce a method using an impedance model for constructing the master-slave system. We confirmed the effectiveness of the positioning control algorithm through experiments.

Tapping mode imaging with an interfacial force microscope

NASA Astrophysics Data System (ADS)

Warren, O. L.; Graham, J. F.; Norton, P. R.

1997-11-01

In their present embodiment, sensors used in interfacial force microscopy do not have the necessary mechanical bandwidth to be employed as free-running tapping mode devices. We describe an extremely stable method of obtaining tapping mode images using feedback on the sensor. Our method is immune to small dc drifts in the force signal, and the prospect of diminishing the risk of damaging fragile samples is realized. The feasibility of the technique is demonstrated by our imaging work on a Kevlar fiber-epoxy composite. We also present a model which accounts for the frequency dependence of the sensor in air when operating under closed loop control. A simplified force modulation model is investigated to explore the effect of contact on the closed loop response of the sensor.

Chiral EFT based nuclear forces: achievements and challenges

NASA Astrophysics Data System (ADS)

Machleidt, R.; Sammarruca, F.

2016-08-01

During the past two decades, chiral effective field theory has become a popular tool to derive nuclear forces from first principles. Two-nucleon interactions have been worked out up to sixth order of chiral perturbation theory and three-nucleon forces up to fifth order. Applications of some of these forces have been conducted in nuclear few- and many-body systems—with a certain degree of success. But in spite of these achievements, we are still faced with great challenges. Among them is the issue of a proper uncertainty quantification of predictions obtained when applying these forces in ab initio calculations of nuclear structure and reactions. A related problem is the order by order convergence of the chiral expansion. We start this review with a pedagogical introduction and then present the current status of the field of chiral nuclear forces. This is followed by a discussion of representative examples for the application of chiral two- and three-body forces in the nuclear many-body system including convergence issues.

Determination of forces in a magnetic bearing actuator - Numerical computation with comparison to experiment

NASA Technical Reports Server (NTRS)

Knight, J. D.; Xia, Z.; Mccaul, E.; Hacker, H., Jr.

1992-01-01

Calculations of the forces exerted on a journal by a magnetic bearing actuator are presented, along with comparisons to experimentally measured forces. The calculations are based on two-dimensional solutions for the flux distribution in the metal parts and free space, using finite but constant permeability in the metals. Above a relative permeability of 10,000 the effects of changes in permeability are negligible, but below 10,000 decreases in permeability cause significant decreases in the force. The calculated forces are shown to depend on the metal permeability more strongly when the journal is displaced from its centered position. The predicted forces in the principal attractive direction are in good agreement with experiment when a relatively low value of permeability is chosen. The forces measured normal to the axis of symmetry when the journal is displaced from that axis, however, are significantly higher than predicted by theory, even with a value of relative permeability larger than 5000. These results indicate a need for further work including nonlinear permeability distributions.

Labor Force

ERIC Educational Resources Information Center

Occupational Outlook Quarterly, 2012

2012-01-01

The labor force is the number of people ages 16 or older who are either working or looking for work. It does not include active-duty military personnel or the institutionalized population, such as prison inmates. Determining the size of the labor force is a way of determining how big the economy can get. The size of the labor force depends on two…

GNSS orbit determination by precise modeling of non-gravitational forces acting on satellite's body

NASA Astrophysics Data System (ADS)

Wielgosz, Agata; Kalarus, Maciej; Liwosz, Tomasz

2016-04-01

Satellites orbiting around Earth are affected by gravitational forces and non-gravitational perturbations (NGP). While the perturbations caused by gravitational forces, which are due to central body gravity (including high-precision geopotential field) and its changes (due to secular variations and tides), solar bodies attraction and relativistic effects are well-modeled, the perturbations caused by the non-gravitational forces are the most limiting factor in Precise Orbit Determination (POD). In this work we focused on very precise non-gravitational force modeling for medium Earth orbit satellites by applying the various models of solar radiation pressure including changes in solar irradiance and Earth/Moon shadow transition, Earth albedo and thermal radiation. For computing influence of aforementioned forces on spacecraft the analytical box-wing satellite model was applied. Smaller effects like antenna thrust or spacecraft thermal radiation were also included. In the process of orbit determination we compared the orbit with analytically computed NGP with the standard procedure in which CODE model is fitted for NGP recovery. We considered satellites from several systems and on different orbits and for different periods: when the satellite is all the time in full sunlight and when transits the umbra and penumbra regions.

Calculating forces on thin flat plates with incomplete vorticity-field data

NASA Astrophysics Data System (ADS)

Limacher, Eric; Morton, Chris; Wood, David

2016-11-01

Optical experimental techniques such as particle image velocimetry (PIV) permit detailed quantification of velocities in the wakes of bluff bodies. Patterns in the wake development are significant to force generation, but it is not trivial to quantitatively relate changes in the wake to changes in measured forces. Key difficulties in this regard include: (i) accurate quantification of velocities close to the body, and (ii) the effect of missing velocity or vorticity data in regions where optical access is obscured. In the present work, we consider force formulations based on the vorticity field, wherein mathematical manipulation eliminates the need for accurate near-body velocity information. Attention is restricted to nominally two dimensional problems, namely (i) a linearly accelerating flat plate, investigated using PIV in a water tunnel, and (ii) a pitching plate in a freestream flow, as investigated numerically by Wang & Eldredge (2013). The effect of missing vorticity data on the pressure side of the plate has a significant impact on the calculation of force for the pitching plate test case. Fortunately, if the vorticity on the pressure side remains confined to a thin boundary layer, simple corrections can be applied to recover a force estimate.

A mean-density model of ionic surfactants for the dispersion of carbon nanotubes in aqueous solutions

NASA Astrophysics Data System (ADS)

Joung, Young Soo

2018-05-01

We propose a new analytical model of ionic surfactants used for the dispersion of carbon nanotubes (CNTs) in aqueous solutions. Although ionic surfactants are commonly used to facilitate the dispersion of CNTs in aqueous solutions, understanding the dispersion process is challenging and time-consuming owing to its complexity and nonlinearity. In this work, we develop a mean-density model of ionic surfactants to simplify the calculation of interaction forces between CNTs stabilized by ionic surfactants. Using this model, we can evaluate various interaction forces between the CNTs and ionic surfactants under different conditions. The dispersion mechanism is investigated by estimating the potential of mean force (PMF) as a function of van der Waals forces, electrostatic forces, interfacial tension, and osmotic pressure. To verify the proposed model, we compare the PMFs derived using our method with those derived from molecular dynamics simulations using comparable CNTs and ionic surfactants. Notably, for stable dispersions, the osmotic pressure and interfacial energy are important for long-range and short-range interactions, respectively, in comparison with the effect of electrostatic forces. Our model effectively prescribes specific surfactants and their concentrations to achieve stable aqueous suspensions of CNTs.

SHOULDER DISORDERS AND OCCUPATION

PubMed Central

Linaker, CH; Walker-Bone, K

2016-01-01

Shoulder pain is very common and causes substantial morbidity. Standardised classification systems based upon presumed patho-anatomical origins have proved poorly reproducible and hampered epidemiological research. Despite this, there is evidence that exposure to combinations of physical workplace strains such as overhead working, heavy lifting and forceful work as well as working in an awkward posture increase the risk of shoulder disorders. Psychosocial risk factors are also associated. There is currently little evidence to suggest that either primary prevention or treatment strategies in the workplace are very effective and more research is required, particularly around the cost-effectiveness of different strategies. PMID:26612238

Thermal Casimir-Polder forces on a V-type three-level atom

NASA Astrophysics Data System (ADS)

Xu, Chen-Ran; Xu, Jing-Ping; Al-amri, M.; Zhu, Cheng-Jie; Xie, Shuang-Yuan; Yang, Ya-Ping

2017-09-01

We study the thermal Casimir-Polder (CP) forces on a V-type three-level atom. The competition between the thermal effect and the quantum interference of the two transition dipoles on the force is investigated. To shed light onto the role of the quantum interference, we analyze two kinds of initial states of the atom, i.e., the superradiant state and the subradiant state. Considering the atom being in the thermal reservoir, the resonant CP force arising from the real photon emission dominates in the evolution of the CP force. Under the zero-temperature condition, the quantum interference can effectively modify the amplitude and the evolution of the force, leading to a long-time force or even the cancellation of the force. Our results reveal that in the finite-temperature case, the thermal photons can enhance the amplitude of all force elements, but have no influence on the net resonant CP force in the steady state, which means that the second law of thermodynamics still works. For the ideal degenerate V-type atom with parallel dipoles under the initial subradiant state, the robust destructive quantum interference overrides the thermal fluctuations, leading to the trapping of the atom in the subradiant state and the disappearance of the CP force. However, in terms of a realistic Zeeman atom, the thermal photons play a significant role during the evolution of the CP force. The thermal fluctuations can enhance the amplitude of the initial CP force by increasing the temperature, and weaken the influence of the quantum interference on the evolution of the CP force from the initial superradiant (subradiant) state to the steady state.

Changes in the Nature and Structure of Work: Implications for Employer-Sponsored Training.

ERIC Educational Resources Information Center

Bailey, Thomas

Profound changes in the economy and the labor market have an effect on the role of employer-sponsored training in preparing and educating the country's work force. On the demand side of the labor market, these changes include the increase in international trade, the changing economic status of the United States relative to its trading partners,…

The Effects on the Structure of Society of the Growing Number of Women in the Work Force.

ERIC Educational Resources Information Center

Cook, Alice H.

Women's participation in the workforce is increasing, spurred by inflation, the rising level of consumer aspirations, the increasing number of families headed by women as a consequence of divorce, and the declining birth rate. However, the work women do continues to be segregated from men's and comparatively poorly paid, while women still carry…

Effect of repeated compaction of tablets on tablet properties and work of compaction using an instrumented laboratory tablet press.

PubMed

Gamlen, Michael John Desmond; Martini, Luigi G; Al Obaidy, Kais G

2015-01-01

The repeated compaction of Avicel PH101, dicalcium phosphate dihydrate (DCP) powder, 50:50 DCP/Avicel PH101 and Starch 1500 was studied using an instrumented laboratory tablet press which measures upper punch force, punch displacement and ejection force and operates using a V-shaped compression profile. The measurement of work compaction was demonstrated, and the test materials were ranked in order of compaction behaviour Avicel PH101 > DCP/Avicel PH101 > Starch > DCP. The behaviour of the DCP/Avicel PH101 mixture was distinctly non-linear compared with the pure components. Repeated compaction and precompression had no effect on the tensile fracture strength of Avicel PH101 tablets, although small effects on friability and disintegration time were seen. Repeated compaction and precompression reduced the tensile strength and the increased disintegration time of the DCP tablets, but improved the strength and friability of Starch 1500 tablets. Based on the data reported, routine laboratory measurement of tablet work of compaction may have potential as a critical quality attribute of a powder blend for compression. The instrumented press was suitable for student use with minimal supervisor input.

Jeans instability in collisional strongly coupled dusty plasma with radiative condensation and polarization force

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prajapati, R. P., E-mail: prajapati-iter@yahoo.co.in; Bhakta, S.; Chhajlani, R. K.

2016-05-15

The influence of dust-neutral collisions, polarization force, and electron radiative condensation is analysed on the Jeans (gravitational) instability of partially ionized strongly coupled dusty plasma (SCDP) using linear perturbation (normal mode) analysis. The Boltzmann distributed ions, dynamics of inertialess electrons, charged dust and neutral particles are considered. Using the plane wave solutions, a general dispersion relation is derived which is modified due to the presence of dust-neutral collisions, strong coupling effect, polarization force, electron radiative condensation, and Jeans dust/neutral frequencies. In the long wavelength perturbations, the Jeans instability criterion depends upon strong coupling effect, polarization interaction parameter, and thermal loss,more » but it is independent of dust-neutral collision frequency. The stability of the considered configuration is analysed using the Routh–Hurwitz criterion. The growth rates of Jeans instability are illustrated, and stabilizing influence of viscoelasticity and dust-neutral collision frequency while destabilizing effect of electron radiative condensation, polarization force, and Jeans dust-neutral frequency ratio is observed. This work is applied to understand the gravitational collapse of SCDP with dust-neutral collisions.« less

Novel Approach to Measuring the Droplet Detachment Force from Fibers.

PubMed

Amrei, M M; Venkateshan, D G; D'Souza, N; Atulasimha, J; Tafreshi, H Vahedi

2016-12-20

Determining the force required to detach a droplet from a fiber or from an assembly of fibers is of great importance to many applications. A novel technique is developed in this work to measure this force experimentally by using ferrofluid droplets in a magnetic field. Unlike previous methods reported in the literature, our technique does not require air flow or a mechanical object to detach the droplet from the fiber(s); therefore, it simplifies the experiment and also allows one to study the capillarity of the droplet-fiber system in a more isolated environment. In this article, we investigated the effects of the relative angle between intersecting fibers on the force required to detach a droplet from the fibers in the in-plane or out-of-plane direction. The in-plane and through-plane detachment forces were also predicted via numerical simulation and compared with the experimental results. Good agreement was observed between the numerical and experimental results. It was found that the relative angle between intersecting fibers has no significant effect on the detachment force in the out-of-plane direction. However, the detachment force in the in-plane direction depends strongly on the relative angle between the fibers, and it increases as this angle increases.

Surface stress mediated image force and torque on an edge dislocation

NASA Astrophysics Data System (ADS)

Raghavendra, R. M.; Divya, Iyer, Ganesh; Kumar, Arun; Subramaniam, Anandh

2018-07-01

The proximity of interfaces gives prominence to image forces experienced by dislocations. The presence of surface stress alters the traction-free boundary conditions existing on free-surfaces and hence is expected to alter the magnitude of the image force. In the current work, using a combined simulation of surface stress and an edge dislocation in a semi-infinite body, we evaluate the configurational effects on the system. We demonstrate that if the extra half-plane of the edge dislocation is parallel to the surface, the image force (glide) is not altered due to surface stress; however, the dislocation experiences a torque. The surface stress breaks the 'climb image force' symmetry, thus leading to non-equivalence between positive and negative climb. We discover an equilibrium position for the edge dislocation in the positive 'climb geometry', arising due to a competition between the interaction of the dislocation stress fields with the surface stress and the image dislocation. Torque in the climb configuration is not affected by surface stress (remains zero). Surface stress is computed using a recently developed two-scale model based on Shuttleworth's idea and image forces using a finite element model developed earlier. The effect of surface stress on the image force and torque experienced by the dislocation monopole is analysed using illustrative 3D models.

Influence of non-edible vegetable based oil as cutting fluid on chip, surface roughness and cutting force during drilling operation of Mild Steel

NASA Astrophysics Data System (ADS)

Susmitha, M.; Sharan, P.; Jyothi, P. N.

2016-09-01

Friction between work piece-cutting tool-chip generates heat in the machining zone. The heat generated reduces the tool life, increases surface roughness and decreases the dimensional sensitiveness of work material. This can be overcome by using cutting fluids during machining. They are used to provide lubrication and cooling effects between cutting tool and work piece and cutting tool and chip during machining operation. As a result, important benefits would be achieved such longer tool life, easy chip flow and higher machining quality in the machining processes. Non-edible vegetable oils have received considerable research attention in the last decades owing to their remarkable improved tribological characteristics and due to increasing attention to environmental issues, have driven the lubricant industry toward eco friendly products from renewable sources. In the present work, different non-edible vegetable oils are used as cutting fluid during drilling of Mild steel work piece. Non-edible vegetable oils, used are Karanja oil (Honge), Neem oil and blend of these two oils. The effect of these cutting fluids on chip formation, surface roughness and cutting force are investigated and the results obtained are compared with results obtained with petroleum based cutting fluids and dry conditions.

The Effect of Twins on Critical Currents of High Tc Superconductors

DTIC Science & Technology

1989-01-01

particles to stick together due to electrostatic forces. To overcome this we have formed a slurry of the material in liquid nitrogen and flash...can use and the liquid convection tends to counteract the separation process. We have-now designed a magnetic track which particles will slide down with...Currents of High Tc Superconductors" - A.M. Campbell and M.F. Ashby The initial work on levitation forces and separation of superconducting powders has

New design for inertial piezoelectric motors

NASA Astrophysics Data System (ADS)

Liu, Lige; Ge, Weifeng; Meng, Wenjie; Hou, Yubin; Zhang, Jing; Lu, Qingyou

2018-03-01

We have designed, implemented, and tested a novel inertial piezoelectric motor (IPM) that is the first IPM to have controllable total friction force, which means that it sticks with large total friction forces and slips with severely reduced total friction forces. This allows the IPM to work with greater robustness and produce a larger output force at a lower threshold voltage while also providing higher rigidity. This is a new IPM design that means that the total friction force can be dramatically reduced or even canceled where necessary by pushing the clamping points at the ends of a piezoelectric tube that contains the sliding shaft inside it in the opposite directions during piezoelectric deformation. Therefore, when the shaft is propelled forward by another exterior piezoelectric tube, the inner piezoelectric tube can deform to reduce the total friction force acting on the shaft instantly and cause more effective stepping movement of the shaft. While our new IPM requires the addition of another piezoelectric tube, which leads to an increase in volume of 120% when compared with traditional IPMs, the average step size has increased by more than 400% and the threshold voltage has decreased by more than 50 V. The improvement in performance is far more significant than the increase in volume. This enhanced performance will allow the proposed IPM to work under large load conditions where a simple and powerful piezoelectric motor is needed.

Atmospheric stability and complex terrain: comparing measurements and CFD

NASA Astrophysics Data System (ADS)

Koblitz, T.; Bechmann, A.; Berg, J.; Sogachev, A.; Sørensen, N.; Réthoré, P.-E.

2014-12-01

For wind resource assessment, the wind industry is increasingly relying on Computational Fluid Dynamics models that focus on modeling the airflow in a neutrally stratified surface layer. So far, physical processes that are specific to the atmospheric boundary layer, for example the Coriolis force, buoyancy forces and heat transport, are mostly ignored in state-of-the-art flow solvers. In order to decrease the uncertainty of wind resource assessment, the effect of thermal stratification on the atmospheric boundary layer should be included in such models. The present work focuses on non-neutral atmospheric flow over complex terrain including physical processes like stability and Coriolis force. We examine the influence of these effects on the whole atmospheric boundary layer using the DTU Wind Energy flow solver EllipSys3D. To validate the flow solver, measurements from Benakanahalli hill, a field experiment that took place in India in early 2010, are used. The experiment was specifically designed to address the combined effects of stability and Coriolis force over complex terrain, and provides a dataset to validate flow solvers. Including those effects into EllipSys3D significantly improves the predicted flow field when compared against the measurements.

Manipulation of nanoparticles of different shapes inside a scanning electron microscope

PubMed Central

Polyakov, Boris; Dorogin, Leonid M; Butikova, Jelena; Antsov, Mikk; Oras, Sven; Lõhmus, Rünno; Kink, Ilmar

2014-01-01

Summary In this work polyhedron-like gold and sphere-like silver nanoparticles (NPs) were manipulated on an oxidized Si substrate to study the dependence of the static friction and the contact area on the particle geometry. Measurements were performed inside a scanning electron microscope (SEM) that was equipped with a high-precision XYZ-nanomanipulator. To register the occurring forces a quartz tuning fork (QTF) with a glued sharp probe was used. Contact areas and static friction forces were calculated by using different models and compared with the experimentally measured force. The effect of NP morphology on the nanoscale friction is discussed. PMID:24605279

Trapping and assembling of particles and live cells on large-scale random gold nano-island substrates

PubMed Central

Kang, Zhiwen; Chen, Jiajie; Wu, Shu-Yuen; Chen, Kun; Kong, Siu-Kai; Yong, Ken-Tye; Ho, Ho-Pui

2015-01-01

We experimentally demonstrated the use of random plasmonic nano-islands for optical trapping and assembling of particles and live cells into highly organized pattern with low power density. The observed trapping effect is attributed to the net contribution due to near-field optical trapping force and long-range thermophoretic force, which overcomes the axial convective drag force, while the lateral convection pushes the target objects into the trapping zone. Our work provides a simple platform for on-chip optical manipulation of nano- and micro-sized objects, and may find applications in physical and life sciences. PMID:25928045

The response of the East Asia summer precipitation to greenhouse gases and anthropogenic aerosols

NASA Astrophysics Data System (ADS)

Tian, Fangxing; Dong, Buwen; Robson, Jon; Sutton, Rowan

2017-04-01

The changes of precipitation over China since the mid-20th century display a dipole trend pattern over eastern China, which is known as Southern-Flood-Northern-Drought (SFND) pattern. The trends have been attributed to different factors, such as the changes of aerosol and greenhouse gas emissions. However much less is known about the different effects of these factors on generating the SFND pattern. This work investigated the drivers and dynamical mechanisms by using a atmosphere-ocean-mixed-layer model forced by anthropogenic greenhouse gase (GHG), anthropogenic aerosol (AA) and the combined effects. The model experiments with different forcings indicates that the GHG forcing dominates the precipitation increase, which is stronger over south China than over north China. On the other hand, the drought over north China is dominated by the AA forcing. Analysis of physical processes indicates that the GHG forcing increases the moisture and leads to strong convergence over east China, and then more precipitation. The AA forcing leads to north wind anomalies and generates divergent anomalies over north China, which reduces the precipitation. Further analysis indicates that the changes of the circulation which related to the SFND pattern are forced by the enhancement of the Western North Pacific Subtropical High (WNPSH). Both GHG and AA forcing can enhance the WNPSH by changing the local Hadley cell.

Women of Hispanic Origin in the Labor Force. Facts on Working Women No. 89-1 = La mujer de origen hispano en la fuerza laboral. Facts on Working Women Num. 89-1S.

ERIC Educational Resources Information Center

Women's Bureau (DOL), Washington, DC.

Data on Hispanic women in the labor force between 1978 and 1988 show the following: (1) 6.5 percent of the women in the work force in 1988 were of Hispanic origin (3.6 million); (2) the median age of Hispanic women was 26.1 years, 2-5 years younger than Black or White women; (3) 66 percent of Hispanic women participate in the labor force, a higher…

Force-extension behavior of DNA in the presence of DNA-bending nucleoid associated proteins

NASA Astrophysics Data System (ADS)

Dahlke, K.; Sing, C. E.

2018-02-01

Interactions between nucleoid associated proteins (NAPs) and DNA affect DNA polymer conformation, leading to phenomena such as concentration dependent force-extension behavior. These effects, in turn, also impact the local binding behavior of the protein, such as high forces causing proteins to unbind, or proteins binding favorably to locally bent DNA. We develop a coarse-grained NAP-DNA simulation model that incorporates both force- and concentration-dependent behaviors, in order to study the interplay between NAP binding and DNA conformation. This model system includes multi-state protein binding and unbinding, motivated by prior work, but is now dependent on the local structure of the DNA, which is related to external forces acting on the DNA strand. We observe the expected qualitative binding behavior, where more proteins are bound at lower forces than at higher forces. Our model also includes NAP-induced DNA bending, which affects DNA elasticity. We see semi-quantitative matching of our simulated force-extension behavior to the reported experimental data. By using a coarse-grained simulation, we are also able to look at non-equilibrium behaviors, such as dynamic extension of a DNA strand. We stretch a DNA strand at different rates and at different NAP concentrations to observe how the time scales of the system (such as pulling time and unbinding time) work in concert. When these time scales are similar, we observe measurable rate-dependent changes in the system, which include the number of proteins bound and the force required to extend the DNA molecule. This suggests that the relative time scales of different dynamic processes play an important role in the behavior of NAP-DNA systems.

The energetic benefits of tendon springs in running: is the reduction of muscle work important?

PubMed

Holt, Natalie C; Roberts, Thomas J; Askew, Graham N

2014-12-15

The distal muscle-tendon units of cursorial species are commonly composed of short muscle fibres and long, compliant tendons. It is assumed that the ability of these tendons to store and return mechanical energy over the course of a stride, thus avoiding the cyclic absorption and regeneration of mechanical energy by active muscle, offers some metabolic energy savings during running. However, this assumption has not been tested directly. We used muscle ergometry and myothermic measurements to determine the cost of force production in muscles acting isometrically, as they could if mechanical energy was stored and returned by tendon, and undergoing active stretch-shorten cycles, as they would if mechanical energy was absorbed and regenerated by muscle. We found no detectable difference in the cost of force production in isometric cycles compared with stretch-shorten cycles. This result suggests that replacing muscle stretch-shorten work with tendon elastic energy storage and recovery does not reduce the cost of force production. This calls into question the assumption that reduction of muscle work drove the evolution of long distal tendons. We propose that the energetic benefits of tendons are derived primarily from their effect on muscle and limb architecture rather than their ability to reduce the cyclic work of muscle. © 2014. Published by The Company of Biologists Ltd.

The energetic benefits of tendon springs in running: is the reduction of muscle work important?

PubMed Central

Holt, Natalie C.; Roberts, Thomas J.; Askew, Graham N.

2014-01-01

The distal muscle-tendon units of cursorial species are commonly composed of short muscle fibres and long, compliant tendons. It is assumed that the ability of these tendons to store and return mechanical energy over the course of a stride, thus avoiding the cyclic absorption and regeneration of mechanical energy by active muscle, offers some metabolic energy savings during running. However, this assumption has not been tested directly. We used muscle ergometry and myothermic measurements to determine the cost of force production in muscles acting isometrically, as they could if mechanical energy was stored and returned by tendon, and undergoing active stretch–shorten cycles, as they would if mechanical energy was absorbed and regenerated by muscle. We found no detectable difference in the cost of force production in isometric cycles compared with stretch–shorten cycles. This result suggests that replacing muscle stretch–shorten work with tendon elastic energy storage and recovery does not reduce the cost of force production. This calls into question the assumption that reduction of muscle work drove the evolution of long distal tendons. We propose that the energetic benefits of tendons are derived primarily from their effect on muscle and limb architecture rather than their ability to reduce the cyclic work of muscle. PMID:25394624

Effect of unilateral knee extensor fatigue on force and balance of the contralateral limb.

PubMed

Arora, Shruti; Budden, Shawn; Byrne, Jeannette M; Behm, David G

2015-10-01

Fatigue in one limb can decrease force production in the homologous muscle as well as other muscles of the non-fatigued limb affecting balance. The objective of the study was to examine the effect of unilateral knee extensor fatigue on the non-fatigued limb's standing balance, muscle force and activation. Sixteen healthy male subjects performed pre-fatigue balance trials, warm-up exercises, maximum voluntary isometric contractions, a knee extensors fatigue protocol, and post-fatigue balance trials. The fatigue protocol consisted of sets of 15 consecutive isometric contractions of 16 s each with 4 s recovery between repetitions, which were performed at 30% peak force for the dominant knee extensor muscles. Additional sets of contractions continued until a 50% decrease in MVIC knee extensor force was observed. Pre- and post-fatigue balance assessment consisted of transition from double to single leg standing and also single leg standing trials, which were performed bilaterally and in randomized order. The peak force and F100 were significantly decreased by 44.8% (ES = 2.54) and 39.9% (ES = 0.59), respectively, for the fatigued limb post-fatigue. There were no significant changes in the non-fatigued limb's muscle force, activation, muscle onset timing or postural stability parameters. While the lack of change in non-fatigued limb force production is in agreement with some of the previous literature in this area, the lack of effect on postural measures directly contradicts earlier work. It is hypothesized that discrepancies in the duration and the intensity of the fatigue protocol may have accounted for this discrepancy.

Formability analysis of aluminum alloys through deep drawing process

NASA Astrophysics Data System (ADS)

Pranavi, U.; Janaki Ramulu, Perumalla; Chandramouli, Ch; Govardhan, Dasari; Prasad, PVS. Ram

2016-09-01

Deep drawing process is a significant metal forming process used in the sheet metal forming operations. From this process complex shapes can be manufactured with fewer defects. Deep drawing process has different effectible process parameters from which an optimum level of parameters should be identified so that an efficient final product with required mechanical properties will be obtained. The present work is to evaluate the formability of Aluminum alloy sheets using deep drawing process. In which effects of punch radius, lubricating conditions, die radius, and blank holding forces on deep drawing process observed for AA 6061 aluminum alloy sheet of 2 mm thickness. The numerical simulations are performed for deep drawing of square cups using three levels of aforesaid parameters like lubricating conditions and blank holding forces and two levels of punch radii and die radii. For numerical simulation a commercial FEM code is used in which Hollomon's power law and Hill's 1948 yield criterions are implemented. The deep drawing setup used in the FEM code is modeled using a CAD tool by considering the modeling requirements from the literature. Two different strain paths (150x150mm and 200x200mm) are simulated. Punch forces, thickness distributions and dome heights are evaluated for all the conditions. In addition failure initiation and propagation is also observed. From the results, by increasing the coefficient of friction and blank holding force, punch force, thickness distribution and dome height variations are observed. The comparison has done and the optimistic parameters were suggested from the results. From this work one can predict the formability for different strain paths without experimentation.

The Prediction of the Work of Friction Force on the Arbitrary Path

ERIC Educational Resources Information Center

Matehkolaee, Mehdi Jafari; Majidian, Kourosh

2013-01-01

In this paper we have calculated the work of friction force on the arbitrary path. In our method didn't use from energy conservative conceptions any way. The distinction of this procedure is that at least do decrease measurement on the path once. Thus we can forecast the amount of work of friction force without information about speed of…

Probing physical properties at the nanoscale using atomic force microscopy

NASA Astrophysics Data System (ADS)

Ditzler, Lindsay Rachel

Techniques that measure physical properties at the nanoscale with high sensitivity are significantly limited considering the number of new nanomaterials being developed. The development of atomic force microscopy (AFM) has lead to significant advancements in the ability to characterize physical properties of materials in all areas of science: chemistry, physics, engineering, and biology have made great scientific strides do to the versatility of the AFM. AFM is used for quantification of many physical properties such as morphology, electrical, mechanical, magnetic, electrochemical, binding interactions, and protein folding. This work examines the electrical and mechanical properties of materials applicable to the field of nano-electronics. As electronic devices are miniaturized the demand for materials with unique electrical properties, which can be developed and exploited, has increased. For example, discussed in this work, a derivative of tetrathiafulvalene, which exhibits a unique loss of conductivity upon compression of the self-assembled monolayer could be developed into a molecular switch. This work also compares tunable organic (tetraphenylethylene tetracarboxylic acid and bis(pyridine)s assemblies) and metal-organic (Silver-stilbizole coordination compounds) crystals which show high electrical conductivity. The electrical properties of these materials vary depending on their composition allowing for the development of compositionally tunable functional materials. Additional work was done to investigate the effects of molecular environment on redox active 11-ferroceneyl-1 undecanethiol (Fc) molecules. The redox process of mixed monolayers of Fc and decanethiol was measured using conductive probe atomic force microscopy and force spectroscopy. As the concentration of Fc increased large, variations in the force were observed. Using these variations the number of oxidized molecules in the monolayer was determined. AFM is additionally capable of investigating interactions at the nanoscale, such as ligand-receptor interactions. This work examines the interactions between the enzyme dihydrofolate reductase (DHFR), a widely investigated enzyme targeted for cancer and antimicrobial pharmaceutical, and methotrexate (MTX), a strong competitive inhibitor of DHFR. The DHFR was immobilized on a gold substrate, bound through a single surface cysteine, and maintained catalytic activity. AFM probe was functionalized with MTX and the interaction strength was measured using AFM. This work highlights the versatility of AFM, specifically force spectroscopy for the quantification of electrical, mechanical, and ligand-receptor interactions at the nanoscale.

Force-induced bone growth and adaptation: A system theoretical approach to understanding bone mechanotransduction

NASA Astrophysics Data System (ADS)

Maldonado, Solvey; Findeisen, Rolf

2010-06-01

The modeling, analysis, and design of treatment therapies for bone disorders based on the paradigm of force-induced bone growth and adaptation is a challenging task. Mathematical models provide, in comparison to clinical, medical and biological approaches an structured alternative framework to understand the concurrent effects of the multiple factors involved in bone remodeling. By now, there are few mathematical models describing the appearing complex interactions. However, the resulting models are complex and difficult to analyze, due to the strong nonlinearities appearing in the equations, the wide range of variability of the states, and the uncertainties in parameters. In this work, we focus on analyzing the effects of changes in model structure and parameters/inputs variations on the overall steady state behavior using systems theoretical methods. Based on an briefly reviewed existing model that describes force-induced bone adaptation, the main objective of this work is to analyze the stationary behavior and to identify plausible treatment targets for remodeling related bone disorders. Identifying plausible targets can help in the development of optimal treatments combining both physical activity and drug-medication. Such treatments help to improve/maintain/restore bone strength, which deteriorates under bone disorder conditions, such as estrogen deficiency.

Human rights and mental health among Latin American women in situations of state-sponsored violence. Bibliographic resources.

PubMed

Lykes, M B; Brabeck, M M; Ferns, T; Radan, A

1993-12-01

The Task Force of the American Psychological Association Division 35, Psychology of Women, conducted a literature review of resources from Latin America to examine the social dimensions of state-sponsored violence in Latin America, their effects on socialization and community, and some responses of women surviving these experiences. It limited its review to works of women's groups, progressive organizations, and individual women exploring the effects of war and state-sponsored violence on women's mental health. Recurring emergent themes included the false dichotomy of violence committed against women in public versus that committed in private, silencing of women accompanies state imposed terror, collective resistance to such terror. The resources addressed 3 types of women's experiences of violence: exile within and beyond one's national borders; torture--an extreme form of state-sponsored violence; and nontraditional, culturally appropriate interventions--alternatives to Western models. This review motivated the Task Force to call on their colleagues to contribute to the on-going documentation of state-sponsored violence. Task Force members identified several areas for collaborative research and/or theory development. Psychologists should question the validity of clinical neutrality and examine the particular meanings of non-neutrality within different cultures. For example, some Latin American psychologists reject diagnoses of intrapsychic syndromes (e.g., post-traumatic stress syndrome) and propose concepts that center on the nexus of individuals and social life. The Task Force sees great opportunities for US psychologists to network and to form solidarity-based relationships with Latin American women. It has identified many women's groups working in Latin America. Human rights organizations (e.g., Americas Watch) have formed women's projects. Further work should be done to improve resource exchanges.

Improved pulmonary function in working divers breathing nitrox at shallow depths

NASA Technical Reports Server (NTRS)

Fitzpatrick, Daniel T.; Conkin, Johnny

2003-01-01

INTRODUCTION: There is limited data about the long-term pulmonary effects of nitrox use in divers at shallow depths. This study examined changes in pulmonary function in a cohort of working divers breathing a 46% oxygen enriched mixture while diving at depths less than 12 m. METHODS: A total of 43 working divers from the Neutral Buoyancy Laboratory (NBL), NASA-Johnson Space Center completed a questionnaire providing information on diving history prior to NBL employment, diving history outside the NBL since employment, and smoking history. Cumulative dive hours were obtained from the NBL dive-time database. Medical records were reviewed to obtain the diver's height, weight, and pulmonary function measurements from initial pre-dive, first year and third year annual medical examinations. RESULTS: The initial forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were greater than predicted, 104% and 102%, respectively. After 3 yr of diving at the NBL, both the FVC and FEV1 showed a significant (p < 0.01) increase of 6.3% and 5.5%, respectively. There were no significant changes in peak expiratory flow (PEF), forced mid-expiratory flow rate (FEF(25-75%)), and forced expiratory flow rates at 25%, 50%, and 75% of FVC expired (FEF25%, FEF50%, FEF75%). Cumulative NBL dive hours was the only contributing variable found to be significantly associated with both FVC and FEV1 at 1 and 3 yr. CONCLUSIONS: NBL divers initially belong to a select group with larger than predicted lung volumes. Regular diving with nitrox at shallow depths over a 3-yr period did not impair pulmonary function. Improvements in FVC and FEV1 were primarily due to a training effect.

Job strain and older workers: Can a reduction in job strain help to eliminate the social security drain?

PubMed

Cahalin, Lawrence P

2009-01-01

Job strain is the psychological and physiological response to a lack of control or support in the work environment. It appears to be an important risk factor for continued employment throughout the lifespan. Reducing job strain earlier in a workers life has the potential to have substantial beneficial health effects throughout a workers life. Early screening for job strain should be implemented in known high risk or high strain jobs. This is particularly important since there a fewer younger workers entering the labor force and there will be a growing need for older workers to remain in the workforce. Furthermore, healthier workers will require less medical care and are likely to work longer if they are willing and able. Healthier older workers who are willing and able to work longer will defer receipt of retirement benefits while continuing to pay into the Social Security System. Further investigation of older individuals (1) willingness and motivation to work past the normal retirement age, (2) career and employment security, skills development, and reconciliation of working and non-working life, and (3) job strain and effects of reducing job strain is needed. The current job strain literature has been expanded to the Social Security System arena and suggests that reducing job strain has the potential to help eliminate the Social Security drain by increasing older worker labor force retention.

Sexual harassment at work place: are you safe?

PubMed

Naveed, Anila; Tharani, Ambreen; Alwani, Nasreen

2010-01-01

In today's world women are increasingly participating in the realm of work force, yet they are facing many obstacles in their way. Sexual harassment is one of those obstacles. Sexual harassment at work place is prevalent in every society. It could happen to anyone but women are the targeted victims. Sexual harassment is considered as a traumatic event and the victim may end up in having physical and mental sufferings that hinders a person to work effectively. At an organisational level this may result in decrease work effectiveness, decreased work productivity, high absenteeism, high turnover, and low staff morale. Hence there is a need that, organisations and government should look seriously into this matter. Proper education and training programs should be developed to deal with these issues. The goal must be both to deal with sexual harassment incidents effectively and to prevent the occurrence of future incidents.

The effect of force feedback on student reasoning about gravity, mass, force and motion

NASA Astrophysics Data System (ADS)

Bussell, Linda

The purpose of this study was to examine whether force feedback within a computer simulation had an effect on reasoning by fifth grade students about gravity, mass, force, and motion, concepts which can be difficult for learners to grasp. Few studies have been done on cognitive learning and haptic feedback, particularly with young learners, but there is an extensive base of literature on children's conceptions of science and a number of studies focus specifically on children's conceptions of force and motion. This case study used a computer-based paddleball simulation with guided inquiry as the primary stimulus. Within the simulation, the learner could adjust the mass of the ball and the gravitational force. The experimental group used the simulation with visual and force feedback; the control group used the simulation with visual feedback but without force feedback. The proposition was that there would be differences in reasoning between the experimental and control groups, with force feedback being helpful with concepts that are more obvious when felt. Participants were 34 fifth-grade students from three schools. Students completed a modal (visual, auditory, and haptic) learning preference assessment and a pretest. The sessions, including participant experimentation and interviews, were audio recorded and observed. The interviews were followed by a written posttest. These data were analyzed to determine whether there were differences based on treatment, learning style, demographics, prior gaming experience, force feedback experience, or prior knowledge. Work with the simulation, regardless of group, was found to increase students' understanding of key concepts. The experimental group appeared to benefit from the supplementary help that force feedback provided. Those in the experimental group scored higher on the posttest than those in the control group. The greatest difference between mean group scores was on a question concerning the effects of increased gravitational force.

Canine Supply for Physical Security: An Analysis of the Royal Australian Air Force Military Working Dog Program

DTIC Science & Technology

2016-03-01

PHYSICAL SECURITY: AN ANALYSIS OF THE ROYAL AUSTRALIAN AIR FORCE MILITARY WORKING DOG PROGRAM by Mark W. Powell March 2016 Thesis...AN ANALYSIS OF THE ROYAL AUSTRALIAN AIR FORCE MILITARY WORKING DOG PROGRAM 5. FUNDING NUMBERS 6. AUTHOR(S) Mark W. Powell 7. PERFORMING...increased demand on its physical security elements. Its military working dog (MWD) workforce is required to meet an inventory of 204 by end of year 2023 as

A sensitivity study of fast outlet glaciers to short timescale cyclical perturbations

NASA Astrophysics Data System (ADS)

Aykutlug, E.; Dupont, T. K.

2015-01-01

The dynamic response of outlet glaciers on short (annual to decadal) timescales is affected by various external forcings, such as basal or oceanic conditions. Understanding the sensitivity of the dynamic response to such forcings can help assess more accurate ice volume projections. In this work, we investigate the spatiotemporal sensitivity of outlet glaciers to fast cyclical forcings using a one-dimensional depth and width-averaged heuristic model. Our results indicate that even on such short timescales, nonlinearities in ice dynamics may lead to an asymmetric response, despite the forcing functions being symmetric around each reference value. Results also show that such short-timescale effects become more pronounced as glaciers become closer to flotation. While being qualitatively similar for both downsloping and upsloping bed geometries, the results indicate higher sensitivity for upsloping ("West Antarctica-like") beds. The range in asymmetric response for different configurations motivate parameterizing or including short-timescale effects in models while investigating the dynamic behavior of outlet glaciers.

Developing Lathing Parameters for PBX 9501

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woodrum, Randall Brock

This thesis presents the work performed on lathing PBX 9501 to gather and analyze cutting force and temperature data during the machining process. This data will be used to decrease federal-regulation-constrained machining time of the high explosive PBX 9501. The effects of machining parameters depth of cut, surface feet per minute, and inches per revolution on cutting force and cutting interface were evaluated. Cutting tools of tip radius 0.005 -inches and 0.05 -inches were tested to determine what effect the tool shape had on the machining process as well. A consistently repeatable relationship of temperature to changing depth of cutmore » and surface feet per minute is found, while only a weak dependence was found to changing inches per revolution. Results also show the relation of cutting force to depth of cut and inches per revolution, while weak dependence on SFM is found. Conclusions suggest rapid, shallow cuts optimize machining time for a billet of PBX 9501, while minimizing temperature increase and cutting force.« less

Adhesion force interactions between cyclopentane hydrate and physically and chemically modified surfaces.

PubMed

Aman, Zachary M; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

2014-12-07

Interfacial interactions between liquid-solid and solid-solid phases/surfaces are of fundamental importance to the formation of hydrate deposits in oil and gas pipelines. This work establishes the effect of five categories of physical and chemical modification to steel on clathrate hydrate adhesive force: oleamide, graphite, citric acid ester, nonanedithiol, and Rain-X anti-wetting agent. Hydrate adhesive forces were measured using a micromechanical force apparatus, under both dry and water-wet surface conditions. The results show that the graphite coating reduced hydrate-steel adhesion force by 79%, due to an increase in the water wetting angle from 42 ± 8° to 154 ± 7°. Two chemical surface coatings (nonanedithiol and the citric acid ester) induced rapid hydrate growth in the hydrate particles; nonanedithiol increased hydrate adhesive force by 49% from the baseline, while the citric acid ester coating reduced hydrate adhesion force by 98%. This result suggests that crystal growth may enable a strong adhesive pathway between hydrate and other crystalline structures, however this effect may be negated in cases where water-hydrocarbon interfacial tension is minimised. When a liquid water droplet was placed on the modified steel surfaces, the graphite and citric acid ester became less effective at reducing adhesive force. In pipelines containing a free water phase wetting the steel surface, chemical or physical surface modifications alone may be insufficient to eliminate hydrate deposition risk. In further tests, the citric acid ester reduced hydrate cohesive forces by 50%, suggesting mild activity as a hybrid anti-agglomerant suppressing both hydrate deposition and particle agglomeration. These results demonstrate a new capability to develop polyfunctional surfactants, which simultaneously limit the capability for hydrate particles to aggregate and deposit on the pipeline wall.

Return on Investment: A Cost-Effectiveness Measure for the Texas' Workforce System.

ERIC Educational Resources Information Center

Norris, Davy N.; King, Christopher T.

Texas is developing a return-on-investment (ROI) measure to assess the cost-effectiveness of work force programs. Emphasis is on issues related to conducting cross-program ROI analysis at the level of the Local Workforce Development Board (LWDB) in career or one-stop centers. To make the most appropriate and effective use of ROI, the following…

An Evaluation of an Attitudinal Model to Measure the Potential for Combat Effectiveness of U.S. Air Force Organizations.

DTIC Science & Technology

1982-09-01

Fight Combat Effectiveness Organizational Assessment Package Morale Combat Effectiveness Model Cohesion Leadership 20. AIISTRACT (COe/Mie do ,eae aide If...of combat readiness. The major psychosocial dimensions which contribute to combat effectiveness of a military unit (morale leadership , cohesion, and...psychosocial dimensions in the combat effectiveness model (morale, leadership , and cohesion) in addition to training, logistics, alienation, and work group

On the performance of Usain Bolt in the 100 m sprint

NASA Astrophysics Data System (ADS)

Hernández Gómez, J. J.; Marquina, V.; Gómez, R. W.

2013-09-01

Many university texts on mechanics consider the effect of air drag force, using the slowing down of a parachute as an example. Very few discuss what happens when the drag force is proportional to both u and u2. In this paper we deal with a real problem to illustrate the effect of both terms on the speed of a runner: a theoretical model of the world-record 100 m sprint of Usain Bolt during the 2009 World Championships in Berlin is developed, assuming a drag force proportional to u and to u2. The resulting equation of motion is solved and fitted to the experimental data obtained from the International Association of Athletics Federations, which recorded Bolt's position with a laser velocity guard device. It is worth noting that our model works only for short sprints.

Electrokinetic-flow-induced viscous drag on a tethered DNA inside a nanopore.

PubMed

Ghosal, Sandip

2007-12-01

Recent work has shown that the resistive force arising from viscous effects within the pore region could explain observed translocation times in certain experiments involving voltage-driven translocations of DNA through nanopores [Ghosal, Phys. Rev. E 71, 051904 (2006); Phys. Rev. Lett. 98, 238104 (2007)]. The electrokinetic flow inside the pore and the accompanying viscous effects also play a crucial role in the interpretation of experiments where the DNA is immobilized inside a nanopore [Keyser, Nat. Phys. 2, 473 (2006)]. In this paper the viscous force is explicitly calculated for a nanopore of cylindrical geometry. It is found that the reductions of the tether force due to viscous drag and due to charge reduction by Manning condensation are of similar size. The result is of importance in the interpretation of experimental data on tethered DNA.

Electromagnetic Properties Analysis on Hybrid-driven System of Electromagnetic Motor

NASA Astrophysics Data System (ADS)

Zhao, Jingbo; Han, Bingyuan; Bei, Shaoyi

2018-01-01

The hybrid-driven system made of permanent-and electromagnets applied in the electromagnetic motor was analyzed, equivalent magnetic circuit was used to establish the mathematical models of hybrid-driven system, based on the models of hybrid-driven system, the air gap flux, air-gap magnetic flux density, electromagnetic force was proposed. Taking the air-gap magnetic flux density and electromagnetic force as main research object, the hybrid-driven system was researched. Electromagnetic properties of hybrid-driven system with different working current modes is studied preliminary. The results shown that analysis based on hybrid-driven system can improve the air-gap magnetic flux density and electromagnetic force more effectively and can also guarantee the output stability, the effectiveness and feasibility of the hybrid-driven system are verified, which proved theoretical basis for the design of hybrid-driven system.

Single particle train ordering in microchannel based on inertial and vortex effects

NASA Astrophysics Data System (ADS)

Fan, Liang-Liang; Yan, Qing; Zhe, Jiang; Zhao, Liang

2018-06-01

A new microfluidic device for microparticle focusing and ordering in a single particle train is reported. The particle focusing and ordering are based on inertial and vortex effects in a microchannel with a series of suddenly contracted and widely expanded structures on one side. In the suddenly contracted regions, particles located near the contracted structures are subjected to a strong wall-effect lift force and momentum-change-induced inertial force due to the highly curved trajectory, migrating to the straight wall. A horizontal vortex is generated downstream of the contracted structure, which prevents the particle from getting close to the wall. In the widely expanded regions, the streamline is curved and no vortex is generated. The shear-gradient lift force and the momentum-change-induced inertial force are dominant for particle lateral migration, driving particles towards the wall of the expanded structures. Eventually, particles are focused and ordered in a single particle train by the combination effects of the inertial forces and the vortex. In comparison with other single-stream particle focusing methods, this device requires no sheath flow, is easy for fabrication and operation, and can work over a wide range of Reynolds numbers from 19.1–142.9. The highly ordered particle chain could be potentially utilized in a variety of lab-chip applications, including micro-flow cytometer, imaging and droplet-based cell entrapment.

Disability, employment and work performance among people with ICD-10 anxiety disorders.

PubMed

Waghorn, Geoff; Chant, David; White, Paul; Whiteford, Harvey

2005-01-01

To ascertain at a population level, patterns of disability, labour force participation, employment and work performance among people with ICD-10 anxiety disorders in comparison to people without disability or long-term health conditions. A secondary analysis was conducted of a probability sample of 42 664 individuals collected in an Australian Bureau of Statistics (ABS) national survey in 1998. Trained lay interviewers using ICD-10 computer-assisted interviews identified household residents with anxiety disorders. Anxiety disorders were associated with: reduced labour force participation, degraded employment trajectories and impaired work performance compared to people without disabilities or long-term health conditions. People with anxiety disorders may need more effective treatments and assistance with completing education and training, joining and rejoining the workforce, developing career pathways, remaining in the workforce and sustaining work performance. A whole-of-government approach appears needed to reduce the burden of disease and increase community labour resources. Implications for clinicians, vocational professionals and policy makers are discussed.

Effect of subthalamic nucleus deep brain stimulation on dual-task cognitive and motor performance in isolated dystonia.

PubMed

Mills, Kelly A; Markun, Leslie C; San Luciano, Marta; Rizk, Rami; Allen, I Elaine; Racine, Caroline A; Starr, Philip A; Alberts, Jay L; Ostrem, Jill L

2015-04-01

Subthalamic nucleus (STN) deep brain stimulation (DBS) can improve motor complications of Parkinson's disease (PD) but may worsen specific cognitive functions. The effect of STN DBS on cognitive function in dystonia patients is less clear. Previous reports indicate that bilateral STN stimulation in patients with PD amplifies the decrement in cognitive-motor dual-task performance seen when moving from a single-task to dual-task paradigm. We aimed to determine if the effect of bilateral STN DBS on dual-task performance in isolated patients with dystonia, who have less cognitive impairment and no dementia, is similar to that seen in PD. Eight isolated predominantly cervical patients with dystonia treated with bilateral STN DBS, with average dystonia duration of 10.5 years and Montreal Cognitive Assessment score of 26.5, completed working memory (n-back) and motor (forced-maintenance) tests under single-task and dual-task conditions while on and off DBS. A multivariate, repeated-measures analysis of variance showed no effect of stimulation status (On vs Off) on working memory (F=0.75, p=0.39) or motor function (F=0.22, p=0.69) when performed under single-task conditions, though as working memory task difficulty increased, stimulation disrupted the accuracy of force-tracking. There was a very small worsening in working memory performance (F=9.14, p=0.019) when moving from single-task to dual-tasks when using the 'dual-task loss' analysis. This study suggests the effect of STN DBS on working memory and attention may be much less consequential in patients with dystonia than has been reported in PD. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Effect of subthalamic nucleus deep brain stimulation on dual-task cognitive and motor performance in isolated dystonia

PubMed Central

Mills, Kelly A; Markun, Leslie C; Luciano, Marta San; Rizk, Rami; Allen, I Elaine; Racine, Caroline A; Starr, Philip A; Alberts, Jay L; Ostrem, Jill L

2015-01-01

Objective Subthalamic nucleus (STN) deep brain stimulation (DBS) can improve motor complications of Parkinson's disease (PD) but may worsen specific cognitive functions. The effect of STN DBS on cognitive function in dystonia patients is less clear. Previous reports indicate that bilateral STN stimulation in patients with PD amplifies the decrement in cognitive-motor dual-task performance seen when moving from a single-task to dual-task paradigm. We aimed to determine if the effect of bilateral STN DBS on dual-task performance in isolated patients with dystonia, who have less cognitive impairment and no dementia, is similar to that seen in PD. Methods Eight isolated predominantly cervical patients with dystonia treated with bilateral STN DBS, with average dystonia duration of 10.5 years and Montreal Cognitive Assessment score of 26.5, completed working memory (n-back) and motor (forced-maintenance) tests under single-task and dual-task conditions while on and off DBS. Results A multivariate, repeated-measures analysis of variance showed no effect of stimulation status (On vs Off) on working memory (F=0.75, p=0.39) or motor function (F=0.22, p=0.69) when performed under single-task conditions, though as working memory task difficulty increased, stimulation disrupted the accuracy of force-tracking. There was a very small worsening in working memory performance (F=9.14, p=0.019) when moving from single-task to dual-tasks when using the ‘dual-task loss’ analysis. Conclusions This study suggests the effect of STN DBS on working memory and attention may be much less consequential in patients with dystonia than has been reported in PD. PMID:25012202

Population and labour force growth and patterns in ASEAN countries.

PubMed

Saw, S

1988-01-01

"The paper shows that the diverse labor dimensions prevailing in the ASEAN region can be attributed to changes in the structure of the society and economy in the course of recent economic development. It observes the considerable variety in the growth of the population and its effect on the labor force in the ASEAN region.... The paper details the similarity and diversity in the level and type of labor force participation rates. A common feature shared by ASEAN countries is a general pattern in the age-specific participation rate of men. In contrast, the women, aside from participating in the labor force at a much lower level than men at almost all ages, display diverse patterns of participation over the working age range. Lastly, the distribution of the labor force according to major industrial sectors in the six ASEAN countries is presented...." excerpt

Influence of the adsorption geometry of PTCDA on Ag(111) on the tip-molecule forces in non-contact atomic force microscopy.

PubMed

Langewisch, Gernot; Falter, Jens; Schirmeisen, André; Fuchs, Harald

2014-01-01

Perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) adsorbed on a metal surface is a prototypical organic-anorganic interface. In the past, scanning tunneling microscopy and scanning tunneling spectroscopy studies of PTCDA adsorbed on Ag(111) have revealed differences in the electronic structure of the molecules depending on their adsorption geometry. In the work presented here, high-resolution 3D force spectroscopy measurements at cryogenic temperatures were performed on a surface area that contained a complete PTCDA unit cell with the two possible geometries. At small tip-molecule separations, deviations in the tip-sample forces were found between the two molecule orientations. These deviations can be explained by a different electron density in both cases. This result demonstrates the capability of 3D force spectroscopy to detect even small effects in the electronic properties of organic adsorbates.

Receiving treatment, labor force activity, and work performance among people with psychiatric disorders: results from a population survey.

PubMed

Waghorn, Geoffrey; Chant, David

2011-12-01

Standard treatments for psychiatric disorders such as schizophrenia, depression and anxiety disorders are generally expected to benefit individuals, employers, and the wider community through improvements in work-functioning and productivity. We repeated a previous secondary investigation of receiving treatment, labor force activity and self-reported work performance among people with ICD-10 psychiatric disorders, in comparison to people with other types of health conditions. Data were collected by the Australian Bureau of Statistics in 2003 repeating a survey administered in 1998 using representative multistage sampling strategies. The 2003 household probability sample consisted of 36,241 working age individuals. Consistent with the previous secondary investigation based on the 1998 survey administration, receiving treatment was consistently associated with non-participation in the labor force, and was negatively associated with work performance. At a population level, receiving treatment was negatively associated with labor force activity and work performance. The stability of these results in two independent surveys highlights the need to investigate the longitudinal relationships between evidence-based treatments for psychiatric conditions as applied in real-world settings, and labor force participation and work performance outcomes.

Force and work to shear green southern pine logs at slow speed

Treesearch

Peter Koch

1971-01-01

When logs of three diameter classes and two specific gravity classes were sheared with a 3/8-inch-thick knife travelling at 2 inches per minute, shearing force and work averaged greatest for dense 13.6-inch logs cut with a knife having a 45o sharpness angle (73,517 pounds; 49,838 foot-pounds). Force and work averaged at least 5.1-inch bolts of...

An Analysis of Section 529 College Savings and Prepaid Tuition Plans. A Report Prepared by the Department of Treasury for the White House Task Force on Middle Class Working Families

ERIC Educational Resources Information Center

US Department of the Treasury, 2009

2009-01-01

Making college education more affordable is a central goal of the Obama Administration and has been a focus of Vice-President Biden's Taskforce on the Middle Class. To that end, the Task Force asked U.S. Treasury Department to prepare this report on how to make Section 529 college savings plans a more effective and reliable tool for families to…

Finding of No Significant Impact (FONSI) for Construction of a Base Civil Engineer Complex at Travis Air Force Base, California

DTIC Science & Technology

2002-01-26

than the target species and have permeable skins. Use of pesticides, such as methoprene , in mosquito abatement may have an indirect adverse effect on...antiterrorism/force protection requirements and provide operational flexibility for the various organizations that would use the complex. Decision After...NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND

The Effects of Continuous One-Arm Kettlebell Swing Training on Physiological Parameters in United States Air Force Personnel: A Pilot Study

DTIC Science & Technology

2016-11-01

collegiate soccer players . KB snatches were performed 3 days per week for 20 minutes with 15-second work-to-rest intervals, while the control group...10] used KB weights that were 18% of total body mass and reported a 6% improvement in aerobic capacity in women’s collegiate soccer players who...Force Personnel: A Pilot Study Molly Wade, MS; Reginald O’Hara, PhD; Lydia Caldwell, MS; Jason Ordway, MS; Darryn Bryant, MS

Towards an on-chip platform for the controlled application of forces via magnetic particles: A novel device for mechanobiology

NASA Astrophysics Data System (ADS)

Monticelli, M.; Albisetti, E.; Petti, D.; Conca, D. V.; Falcone, M.; Sharma, P. P.; Bertacco, R.

2015-05-01

In-vitro tests and analyses are of fundamental importance for investigating biological mechanisms in cells and bio-molecules. The controlled application of forces to activate specific bio-pathways and investigate their effects, mimicking the role of the cellular environment, is becoming a prominent approach in this field. In this work, we present a non-invasive magnetic on-chip platform which allows for the manipulation of magnetic particles, through micrometric magnetic conduits of Permalloy patterned on-chip. We show, from simulations and experiments, that this technology permits to exert a finely controlled force on magnetic beads along the chip surface. This force can be tuned from few to hundreds pN by applying a variable external magnetic field.

The relationship between obesity and forced vital capacity among university students.

PubMed

Sun, Xugui; Chen, Xiaohong

2015-05-01

We sought to explore the relationship between vital capacity and obesity among university students in China. A cross-sectional study was designed to collect the routine health screening data for university students in 2013. The height, weight and force vital capacity of students were measured, and BMI was calculated with height and weight, so as to estimate the relationship between force vital capacity and obesity. Based on Working Group on Obesity references in China, obesity has a higher force vital capacity in both male and female university students. No correlation was found between vital capacity and BMI. obesity may have effect on pulmonary function among university students, which is a reference for further epidemic study. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Changes in Wives' Employment when Husbands Stop Working: A Recession-Prosperity Comparison

ERIC Educational Resources Information Center

Mattingly, Marybeth J.; Smith, Kristin E.

2010-01-01

American families are experiencing the effects of the "Great Recession." Most of the job losses are accruing to men, so families may find it strategic for wives to enter the labor force, or increase their work hours. We consider this possibility using the May 2008 and 2009 Current Population Survey, and compare findings to May 2004 and 2005 data,…

Seven Important Labor Force Trends.

ERIC Educational Resources Information Center

Bailey, John A.

1982-01-01

Presents statistics on the changing human resources mix in the labor force, which vocational counselors should be aware of. Trends include higher percentages of women working, and older men and married men leaving the work force. One result is an increasing number of persons are able to retire earlier. (JAC)

[Older female employees in Germany - structures of employment and perspectives of the future].

PubMed

Clemens, W

2006-02-01

This contribution presents an overview to the structures and conditions of employment of older female employees in Germany. Based on information about the labor force participation rates, rates of unemployment and occupational patterns the conditions of female employment beyond midlife are examined. Relating to the standard of living, the meaning of employment for older women is discussed. Furthermore, the effects of regulations of welfare state, i. e., pension systems, on future life of the employed women are highlighted. Further topics are the completion of working life and the transition to retirement of female employees, the issue of the future working conditions of older female employees related with demographic change und future reduction of the potential of labor force. Finally the contribution stresses the importance of a holistic approach to investigate the living and working conditions of older female employees.

[The global harmonization task force : successes and challenges].

PubMed

Rotter, R G

2009-06-01

With the move towards globalized international commerce and trade, a call for harmonization of medical device regulatory requirements and practices has evolved. The purpose of the Global Harmonization Task Force (GHTF) is to encourage convergence of regulatory requirements and practices at a global level through consensus to achieve four principle goals: promote safety, quality and performance/effectiveness of medical devices; encourage technological innovation; foster international trade; and serve as a forum of information exchange - all in the interests of protecting and promoting public health. The GHTF is governed by a Steering Committee, and the principle development of the GHTF regulatory model has been, and continues to be, done through five working groups known as Study Groups and supplemented recently by the creation of several Ad Hoc Working Groups. Since its creation in 1992, the members of the GHTF have worked collaboratively to develop what is now ready to be called a global model for the regulation of medical devices.

Psychosocial job quality and mental health among young workers: a fixed-effects regression analysis using 13 waves of annual data.

PubMed

Milner, Allison; Krnjack, Lauren; LaMontagne, Anthony D

2017-01-01

Objectives Entry into employment may be a time when a young person's well-being and mental health is challenged. Specifically, we examined the difference in mental health when a young person was "not in the labor force" (NILF) (ie, non-working activity such as participating in education) compared to being in a job with varying levels of psychosocial quality. Method The data source for this study was the Household Income and Labor Dynamics in Australia (HILDA) study, and the sample included 10 534 young people (aged ≤30 years). We used longitudinal fixed-effects regression to investigate within-person changes in mental health comparing circumstances where individuals were NILF to when they were employed in jobs of varying psychosocial quality. Results Compared to when individuals were not in the labor force, results suggest a statistically significant decline in mental health when young people were employed in jobs with poor psychosocial working conditions and an improvement in mental health when they were employed in jobs with optimal psychosocial working conditions. Our results were robust to various sensitivity tests, including adjustment for life events and the lagged effects of mental health and job stressors. Conclusions If causal, the results suggest that improving the psychosocial quality of work for younger workers will protect and promote their wellbeing, and may reduce the likelihood of mental health problems later on.

What is the prevalence of and associations with forced labour experiences among male migrants from Dolakha, Nepal? Findings from a cross-sectional study of returnee migrants

PubMed Central

Mak, Joelle; Abramsky, Tanya; Sijapati, Bandita; Kiss, Ligia; Zimmerman, Cathy

2017-01-01

Objectives Growing numbers of people are migrating outside their country for work, and many experience precarious conditions, which have been linked to poor physical and mental health. While international dialogue on human trafficking, forced labour and slavery increases, prevalence data of such experiences remain limited. Methods Men from Dolakha, Nepal, who had ever migrated outside of Nepal for work were interviewed on their experiences, from predeparture to return (n=194). Forced labour was assessed among those who returned within the past 10 years (n=140) using the International Labour Organization's forced labour dimensions: (1) unfree recruitment; (2) work and life under duress; and (3) impossibility to leave employer. Forced labour is positive if any one of the dimensions is positive. Results Participants had worked in India (34%), Malaysia (34%) and the Gulf Cooperation Council countries (29%), working in factories (29%), as labourers/porters (15%) or in skilled employment (12%). Among more recent returnees (n=140), 44% experienced unfree recruitment, 71% work and life under duress and 14% impossibility to leave employer. Overall, 73% experienced forced labour during their most recent labour migration. Forced labour was more prevalent among those who had taken loans for their migration (PR 1.23) and slightly less prevalent among those who had migrated more than once (PR 0.87); however the proportion of those who experienced forced labour was still high (67%). Age, destination and duration of stay were associated with only certain dimensions of forced labour. Conclusion Forced labour experiences were common during recruitment and at destination. Migrant workers need better advice on assessing agencies and brokers, and on accessing services at destinations. As labour migration from Nepal is not likely to reduce in the near future, interventions and policies at both source and destinations need to better address the challenges migrants face so they can achieve safer outcomes. PMID:28801409

Migraine headache and labor market outcomes.

PubMed

Rees, Daniel I; Sabia, Joseph J

2015-06-01

While migraine headache can be physically debilitating, no study has attempted to estimate its effects on labor market outcomes. Using data drawn from the National Longitudinal Study of Adolescent Health, we estimate the effect of being diagnosed with migraine headache on labor force participation, hours worked, and wages. Ordinary least squares (OLS) estimates suggest that migraines are associated with reduced labor force participation and lower wages among females. A negative association between migraine headache and the wages of female respondents is also obtained using an instrumental variables (IV) approach, although the IV estimates are imprecise relative to the OLS estimates. Copyright © 2014 John Wiley & Sons, Ltd.

Work/Family Interactions: Trends and Applications.

ERIC Educational Resources Information Center

Engelbrecht, JoAnn D.; Nies, Joyce I.

1988-01-01

The authors discuss five trends and how family life educators can address them. The trends are (1) women's labor force participation, (2) growth of the service sector, (3) recognition that work and family life affect each other, (4) space sharing by work and family life, and (5) aging of the work force. (CH)

Fluctuation spectra and force generation in nonequilibrium systems.

PubMed

Lee, Alpha A; Vella, Dominic; Wettlaufer, John S

2017-08-29

Many biological systems are appropriately viewed as passive inclusions immersed in an active bath: from proteins on active membranes to microscopic swimmers confined by boundaries. The nonequilibrium forces exerted by the active bath on the inclusions or boundaries often regulate function, and such forces may also be exploited in artificial active materials. Nonetheless, the general phenomenology of these active forces remains elusive. We show that the fluctuation spectrum of the active medium, the partitioning of energy as a function of wavenumber, controls the phenomenology of force generation. We find that, for a narrow, unimodal spectrum, the force exerted by a nonequilibrium system on two embedded walls depends on the width and the position of the peak in the fluctuation spectrum, and oscillates between repulsion and attraction as a function of wall separation. We examine two apparently disparate examples: the Maritime Casimir effect and recent simulations of active Brownian particles. A key implication of our work is that important nonequilibrium interactions are encoded within the fluctuation spectrum. In this sense, the noise becomes the signal.

Experiments evaluating compliance and force feedback effect on manipulator performance

NASA Technical Reports Server (NTRS)

Kugath, D. A.

1972-01-01

The performance capability was assessed of operators performing simulated space tasks using manipulator systems which had compliance and force feedback varied. Two manipulators were used, the E-2 electromechanical man-equivalent (force, reach, etc.) master-slave system and a modified CAM 1400 hydraulic master-slave with 100 lbs force capability at reaches of 24 ft. The CAM 1400 was further modified to operate without its normal force feedback. Several experiments and simulations were performed. The first two involved the E-2 absorbing the energy of a moving mass and secondly, guiding a mass thru a maze. Thus, both work and self paced tasks were studied as servo compliance was varied. Three simulations were run with the E-2 mounted on the CAM 1400 to evaluate the concept of a dexterous manipulator as an end effector of a boom-manipulator. Finally, the CAM 1400 performed a maze test and also simulated the capture of a large mass as the servo compliance was varied and with force feedback included and removed.

Force feedback controls motor activity and mechanical properties of self-assembling branched actin networks

PubMed Central

Bieling, Peter; Li, Tai-De; Weichsel, Julian; McGorty, Ryan; Jreij, Pamela; Huang, Bo; Fletcher, Daniel A.; Mullins, R. Dyche

2016-01-01

Branched actin networks–created by the Arp2/3 complex, capping protein, and a nucleation promoting factor– generate and transmit forces required for many cellular processes, but their response to force is poorly understood. To address this, we assembled branched actin networks in vitro from purified components and used simultaneous fluorescence and atomic force microscopy to quantify their molecular composition and material properties under various forces. Remarkably, mechanical loading of these self-assembling materials increases their density, power, and efficiency. Microscopically, increased density reflects increased filament number and altered geometry, but no change in average length. Macroscopically, increased density enhances network stiffness and resistance to mechanical failure beyond those of isotropic actin networks. These effects endow branched actin networks with memory of their mechanical history that shapes their material properties and motor activity. This work reveals intrinsic force feedback mechanisms by which mechanical resistance makes self-assembling actin networks stiffer, stronger, and more powerful. PMID:26771487

Work-Family Spillover and Daily Reports of Work and Family Stress in the Adult Labor Force.

ERIC Educational Resources Information Center

Grzywacz, Joseph G.; Almeida, David M.; McDonald, Daniel A.

2002-01-01

Data from two affiliated national surveys were used to examine distribution of work-family spillover among working adults. Analyses testing family life course hypotheses indicated self-reported negative and positive spillover between work and family were not randomly distributed within the labor force. Age was found to have a persistent…

In Flight Evaluation of Active Inceptor Force-Feel Characteristics and Handling Qualities

NASA Technical Reports Server (NTRS)

Lusardi, Jeff A.; Blanken, Chris L.; Ott, Carl Raymond; Malpica, Carlos A.; von Gruenhagen, Wolfgang

2012-01-01

The effect of inceptor feel-system characteristics on piloted handling qualities has been a research topic of interest for many years. Most of the research efforts have focused on advanced fly-by-wire fixed-wing aircraft with only a few studies investigating the effects on rotorcraft. Consequently, only limited guidance is available on how cyclic force-feel characteristics should be set to obtain optimal handling qualities for rotorcraft. To study this effect, the U.S. Army Aeroflightdynamics Directorate working with the DLR Institute of Flight Systems in Germany under Task X of the U.S. German Memorandum of Understanding have been conducting flight test evaluations. In the U.S., five experimental test pilots have completed evaluations of two Mission Task Elements (MTEs) from ADS-33E-PRF and two command/response types for a matrix of center-stick cyclic force-feel characteristics at Moffett Field. In Germany, three experimental test Pilots have conducted initial evaluations of the two MTEs with two command/response types for a parallel matrix of side-stick cyclic force-feel characteristics at WTD-61 in Manching. The resulting data set is used to correlate the effect of changes in natural frequency and damping ratio of the cyclic inceptor on the piloted handling qualities. Existing criteria in ADS-33E and a proposed Handling Qualities Sensitivity Function that includes the effects of the cyclic force-feel characteristics are also evaluated against the data set and discussed.

Seasonality of Forcing by Carbonaceous Aerosols

NASA Astrophysics Data System (ADS)

Habib, G.; Bond, T.; Rasch, P. J.; Coleman, D.

2006-12-01

Aerosols can influence the energy balance of Earth-Atmosphere system with profound effect on regional climate. Atmospheric processes, such as convection, scavenging, wet and dry deposition, govern the lifetime and location of aerosol; emissions affect its quantity and location. Both affect climate forcing. Here we investigate the effect of seasonality in emissions and atmospheric processes on radiative forcing by carbonaceous aerosols, focusing on aerosol from fossil fuel and biofuel. Because aerosol lifetime is seasonal, ignoring the seasonality of sources such as residential biofuel may introduce a bias in aerosol burden and therefore in predicted climate forcing. We present a global emission inventory of carbonaceous aerosols with seasonality, and simulate atmospheric concentrations using the Community Atmosphere Model (CAM). We discuss where and when the seasonality of emissions and atmospheric processes has strong effects on atmospheric burden, lifetime, climate forcing and aerosol optical depth (AOD). Previous work has shown that aerosol forcing is higher in summer than in winter, and has identified the importance of aerosol above cloud in determining black carbon forcing. We show that predicted cloud height is a very important factor in determining normalized radiative forcing (forcing per mass), especially in summer. This can affect the average summer radiative forcing by nearly 50%. Removal by cloud droplets is the dominant atmospheric cleansing mechanism for carbonaceous aerosols. We demonstrate the modeled seasonality of removal processes and compare the importance of scavenging by warm and cold clouds. Both types of clouds contribute significantly to aerosol removal. We estimate uncertainty in direct radiative forcing due to scavenging by tagging the aerosol which has experienced cloud interactions. Finally, seasonal variations offer an opportunity to assess modeled processes when a single process dominates variability. We identify regions where aerosol burden is most sensitive to convection and scavenging in warm and cold clouds, and compare seasonally modeled AOD with that retrieved by the Moderate Resolution Imaging Spectroradiometer (MODIS).

A comparative work on vibration control of a quarter car suspension system with two different magneto-rheological dampers

NASA Astrophysics Data System (ADS)

Park, Jhin Ha; Kim, Wan Ho; Shin, Cheol Soo; Choi, Seung-Bok

2017-01-01

This work compares the ride comfort of a passenger vehicle whose suspension system is equipped with two different magneto-rheological (MR) dampers: with and without bypass holes in the piston. In order to achieve this goal, two cylindrical type MR dampers, which otherwise have the same such geometrical dimensions as radius of piston, length of pole and distance between two poles, are designed based on a mathematical model and subsequently manufactured. One of MR dampers is then modified by making bypass holes in the piston bobbin structure to obtain a relatively low slope of damping force in the pre-yield region. The field-dependent damping force characteristics are investigated through both simulation and experiment. After characterizing the field-dependent damping force of the two MR dampers, a quarter car model is established to evaluate the ride comfort. In this work, a simple but very effective sky-hook controller is adopted, and vibration control performance is evaluated under two road profiles: bump and random road excitations. It is demonstrated through simulation and experiment that the MR damper with bypass holes provides better ride comfort to the car so equipped than that without.

Maximal strength training improves work economy, rate of force development and maximal strength more than conventional strength training.

PubMed

Heggelund, Jørn; Fimland, Marius S; Helgerud, Jan; Hoff, Jan

2013-06-01

This study compared maximal strength training (MST) with equal training volume (kg × sets × repetitions) of conventional strength training (CON) primarily with regard to work economy, and second one repetition maximum (1RM) and rate of force development (RFD) of single leg knee extension. In an intra-individual design, one leg was randomized to knee-extension MST (4 or 5RM) and the other leg to CON (3 × 10RM) three times per week for 8 weeks. MST was performed with maximal concentric mobilization of force while CON was performed with moderate velocity. Eight untrained or moderately trained men (26 ± 1 years) completed the study. The improvement in gross work economy was -0.10 ± 0.08 L min(-1) larger after MST (P = 0.011, between groups). From pre- to post-test the MST and CON improved net work economy with 31 % (P < 0.001) and 18 % (P = 0.01), respectively. Compared with CON, the improvement in 1RM and dynamic RFD was 13.7 ± 8.4 kg (P = 0.002) and 587 ± 679 N s(-1) (P = 0.044) larger after MST, whereas isometric RFD was of borderline significance 3,028 ± 3,674 N s(-1) (P = 0.053). From pre- to post-test, MST improved 1RM and isometric RFD with 50 % (P < 0.001) and 155 % (P < 0.001), respectively whereas CON improved 1RM and isometric RFD with 35 % (P < 0.001) and 83 % (P = 0.028), respectively. Anthropometric measures of quadriceps femoris muscle mass and peak oxygen uptake did not change. In conclusion, 8 weeks of MST was more effective than CON for improving work economy, 1RM and RFD in untrained and moderately trained men. The advantageous effect of MST to improve work economy could be due to larger improvements in 1RM and RFD.

Application of electrohydrodynamic phenomena to space processing

NASA Technical Reports Server (NTRS)

Jones, T. B.

1975-01-01

The capabilities of electrohydrodynamic (EHD) unit separation, liquid handling/control, and mixing are introduced to industrial chemists and metallurgists, working on specific zero-gravity processes. Previously proposed zero-gravity applications of EHD are presented along with the prominent electrohydrodynamical force effects.

Micromechanism linear actuator with capillary force sealing

DOEpatents

Sniegowski, Jeffry J.

1997-01-01

A class of micromachine linear actuators whose function is based on gas driven pistons in which capillary forces are used to seal the gas behind the piston. The capillary forces also increase the amount of force transmitted from the gas pressure to the piston. In a major subclass of such devices, the gas bubble is produced by thermal vaporization of a working fluid. Because of their dependence on capillary forces for sealing, such devices are only practical on the sub-mm size scale, but in that regime they produce very large force times distance (total work) values.

Hispanics in the Work Force, Part II: Hispanic Women.

ERIC Educational Resources Information Center

Escutia, Marta M.; Prieto, Margarita

This paper evaluates the status of Hispanic women in the United States work force. First, demographic information on age patterns, fertility rates, and educational attainment is reviewed. Then, labor market status is assessed in relation to Hispanic women's labor force participation, employment patterns, and poverty. Next, the Federal response to…

Effective charges of ionic liquid determined self-consistently through combination of molecular dynamics simulation and density-functional theory.

PubMed

Ishizuka, Ryosuke; Matubayasi, Nobuyuki

2017-11-15

A self-consistent scheme combining the molecular dynamics (MD) simulation and density functional theory (DFT) was recently proposed to incorporate the effects of the charge transfer and polarization of ions into non-poralizable force fields of ionic liquids for improved description of energetics and dynamics. The purpose of the present work is to analyze the detailed setups of the MD/DFT scheme by focusing on how the basis set, exchange-correlation (XC) functional, charge-fitting method or force field for the intramolecular and Lennard-Jones interactions affects the MD/DFT results of 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl) imide ( [C1mim][NTf2]) and 1-ethyl-3-methylimidazolium glycinate ( [C2mim][Gly]). It was found that the double-zeta valence polarized or larger size of basis set is required for the convergence of the effective charge of the ion. The choice of the XC functional was further not influential as far as the generalized gradient approximation is used. The charge-fitting method and force field govern the accuracy of the MD/DFT scheme, on the other hand. We examined the charge-fitting methods of Blöchl, the iterative Hirshfeld (Hirshfeld-I), and REPEAT in combination with Lopes et al.'s force field and general AMBER force field. There is no single combination of charge fitting and force field that provides good agreements with the experiments, while the MD/DFT scheme reduces the effective charges of the ions and leads to better description of energetics and dynamics compared to the original force field with unit charges. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Crouch gait can be an effective form of forced-use/no constraint exercise for the paretic lower limb in stroke

PubMed Central

Rota, Viviana; Malloggi, Chiara; Brugliera, Luigia; Catino, Luigi

2017-01-01

In hemiplegic gait the paretic lower limb provides less muscle power and shows a briefer stance compared with the unaffected limb. Yet, a longer stance and a higher power can be obtained from the paretic lower limb if gait speed is increased. This supports the existence of a ‘learned non-use’ phenomenon, similar to that underlying some asymmetric impairments of the motion of the eyes and of the upper limbs. Crouch gait (CG) (bent-hip bent-knee, about 30° minimum knee flexion) might be an effective form of ‘forced-use’ treatment of the paretic lower limb. It is not known whether it also stimulates a more symmetric muscle power output. Gait analysis on a force treadmill was carried out in 12 healthy adults and seven hemiplegic patients (1–127 months after stroke, median: 1.6). Speed was imposed at 0.3 m/s. Step length and single and double stance times, sagittal joint rotations, peak positive power, and work in extension of the hip, knee, and ankle (plantar flexion), and surface electromyography (sEMG) area from extensor muscles during the generation of power were measured on either side during both erect and crouch walking. Significance was set at P less than 0.05; corrections for multiplicity were applied. Patients, compared with healthy controls, adopted in both gait modalities and on both sides a shorter step length (61–84%) as well as a shorter stance (76–90%) and swing (63–83%) time. As a rule, they also provided a higher muscular work (median: 137%, range: 77–250%) paralleled by a greater sEMG area (median: 174%, range: 75–185%). In erect gait, the generation of peak extensor power across hip, knee, and ankle joints was in general lower (83–90%) from the paretic limb and higher (98–165%) from the unaffected limb compared with control values. In CG, peak power generation across the three lower limb joints was invariably higher in hemiparetic patients: 107–177% from the paretic limb and 114–231% from the unaffected limb. When gait shifted from erect to crouch, only for hemiplegic patients, at the hip, the paretic/unaffected ratio increased significantly. For peak power, work, sEMG area, and joint rotation, the paretic/unaffected ratio increased from 55 to 85%, 56 to 72%, 68 to 91%, and 67 to 93%, respectively. CG appears to be an effective form of forced-use exercise eliciting more power and work from the paretic lower limb muscles sustained by a greater neural drive. It also seems effective in forcing a more symmetric power and work from the hip extensor muscles, but neither from the knee nor the ankle. PMID:28574860

Women Who Work, Part 2: Married Women in the Labour Force: The Influence of Age, Education, Child-Bearing Status and Residence. Special Labour Force Studies Series B, No. 2.

ERIC Educational Resources Information Center

Allingham, John D.; Spencer, Byron G.

To followup an earlier study of the relative importance of age, education, and marital status as variables influencing female participation in the labor force, this research attempts to measure the relative importance of similar factors in determining whether or not a woman works or wishes to work. Particular emphasis was given to such…

Magnetic Alignment of γ-Fe2O3 Nanoparticles in Polymer Nanocomposites

NASA Astrophysics Data System (ADS)

Jimenez, Andrew; Kumar, Sanat K.; Jestin, Jacques

Recent work in nanocomposites has been heavily focused on controlling the dispersion state of filler particles. The use of internal self-assembly based on matrix properties provides a limited solution to the desire for specified organizations. By introducing a magnetic field during the casting of a polymer solution it has been shown that particles can be oriented to form anisotropic structures - commonly sought after for improved mechanical properties. Here, magnetic nanoparticles were cast in two different polymer matrices to study the effect of various forces that lead to this highly desired alignment. The addition of the magnetic field as an external trigger was shown to not necessarily force the clustering, but rather orient the agglomerates already available in solution. This demonstrates the importance of other dominant forces introduced into the system by characteristics of the polymers themselves. While this magnetic field provides a direction for the sample, the key forces lie in the interactions between the polymers and nanoparticles (as well as their solvent). The study shows a dependence of anisotropy on the particle loading, matrix, and casting time, from which continued work hopes to quantify the clustering necessary to optimize alignment in the composite.

Effect of the tip state during qPlus noncontact atomic force microscopy of Si(100) at 5 K: Probing the probe

PubMed Central

Jarvis, Sam; Danza, Rosanna; Moriarty, Philip

2012-01-01

Summary Background: Noncontact atomic force microscopy (NC-AFM) now regularly produces atomic-resolution images on a wide range of surfaces, and has demonstrated the capability for atomic manipulation solely using chemical forces. Nonetheless, the role of the tip apex in both imaging and manipulation remains poorly understood and is an active area of research both experimentally and theoretically. Recent work employing specially functionalised tips has provided additional impetus to elucidating the role of the tip apex in the observed contrast. Results: We present an analysis of the influence of the tip apex during imaging of the Si(100) substrate in ultra-high vacuum (UHV) at 5 K using a qPlus sensor for noncontact atomic force microscopy (NC-AFM). Data demonstrating stable imaging with a range of tip apexes, each with a characteristic imaging signature, have been acquired. By imaging at close to zero applied bias we eliminate the influence of tunnel current on the force between tip and surface, and also the tunnel-current-induced excitation of silicon dimers, which is a key issue in scanning probe studies of Si(100). Conclusion: A wide range of novel imaging mechanisms are demonstrated on the Si(100) surface, which can only be explained by variations in the precise structural configuration at the apex of the tip. Such images provide a valuable resource for theoreticians working on the development of realistic tip structures for NC-AFM simulations. Force spectroscopy measurements show that the tip termination critically affects both the short-range force and dissipated energy. PMID:22428093

Chewing Gum: Cognitive Performance, Mood, Well-Being, and Associated Physiology

PubMed Central

Allen, Andrew P.; Smith, Andrew P.

2015-01-01

Recent evidence has indicated that chewing gum can enhance attention, as well as promoting well-being and work performance. Four studies (two experiments and two intervention studies) examined the robustness of and mechanisms for these effects. Study 1 investigated the acute effect of gum on mood in the absence of task performance. Study 2 examined the effect of rate and force of chewing on mood and attention performance. Study 3 assessed the effects of chewing gum during one working day on well-being and performance, as well as postwork mood and cognitive performance. In Study 4, performance and well-being were reported throughout the workday and at the end of the day, and heart rate and cortisol were measured. Under experimental conditions, gum was associated with higher alertness regardless of whether performance tasks were completed and altered sustained attention. Rate of chewing and subjective force of chewing did not alter mood but had some limited effects on attention. Chewing gum during the workday was associated with higher productivity and fewer cognitive problems, raised cortisol levels in the morning, and did not affect heart rate. The results emphasise that chewing gum can attenuate reductions in alertness, suggesting that chewing gum enhances worker performance. PMID:26075253

[Investigating work, age, health and work participation in the ageing work force in Germany].

PubMed

Ebener, M; Hasselhorn, H M

2015-04-01

Working life in Germany is changing. The work force is ageing and the number of people available to the labour market will - from now on - shrink considerably. Prospectively, people will have to work longer; but still today, most people leave employment long before reaching official retirement age. What are the reasons for this? In this report, a conceptual framework and the German lidA Cohort Study are presented. The "lidA conceptual framework on work, age, health and work participation" visualises determinants of employment (11 "domains") in higher working age, e. g., "work", "health", "social status" and "life style". The framework reveals 4 key characteristics of withdrawal from work: leaving working life is the result of an interplay of different domains (complexity); (early) retirement is a process with in part early determinants in the life course (processual character); retirement has a strong individual component (individuality); retirement is embedded in a strong structural frame (structure). On the basis of this framework, the "lidA Cohort Study on work, age, health and work participation" (www.lida-studie.de) investigates long-term effects of work on health and work participation in the ageing work force in Germany. It is the only large study in Germany operationalising the concept of employability in a broad interdisciplinary approach. Employees subject to social security and born in 1959 or in 1965 will be interviewed (CAPI) every 3 years (N[wave 1]=6 585, N[wave 2]=4 244) and their data will be linked (where consented) with social security data covering employment history and with health insurance data. The study design ("Schaie's most efficient design") allows for a tri-factor model that isolates the impact of age, cohort and time. In 2014, the second wave was completed. In the coming years lidA will analyse the association of work, health and work participation, and identify age as well as generation differences. lidA will investigate the complexity of work participation and assess the benefit of broader conceptual and methodological research approaches in the field. © Georg Thieme Verlag KG Stuttgart · New York.

The Effect of Interactivity and Instructional Exposure on Learning Effectiveness and Knowledge Retention: A Comparative Study of Two U.S. Air Force Computer-Based Training (CBT) Courses for Network User Licensing

DTIC Science & Technology

2003-03-01

sociocultural theory of learning was pioneered by Lev Vygotsky in the early twentieth century Soviet Union. Although his works were not published...Overview ....................................................................................................................... 14 Learning Theories ...and Teaching Strategies .................................................................. 14 Learning Theories and CBT

The Situational Leadership Approach Effects on Employee Motivation in Multi-Generational Information Technology Organizations

ERIC Educational Resources Information Center

Irby, Thaddaeus

2011-01-01

This study examines the three generations comprising today's IT organizations to determine whether the Situational Leadership approach is effective in motivating this diverse work force to perform project-related tasks. Baby Boomer employees, Generation X employees, and Generation Y employees are the three generations actively employed in IT…

The role of intrinsic muscle mechanics in the neuromuscular control of stable running in the guinea fowl

PubMed Central

Daley, Monica A; Voloshina, Alexandra; Biewener, Andrew A

2009-01-01

Here we investigate the interplay between intrinsic mechanical and neural factors in muscle contractile performance during running, which has been less studied than during walking. We report in vivo recordings of the gastrocnemius muscle of the guinea fowl (Numida meleagris), during the response and recovery from an unexpected drop in terrain. Previous studies on leg and joint mechanics following this perturbation suggested that distal leg extensor muscles play a key role in stabilisation. Here, we test this through direct recordings of gastrocnemius fascicle length (using sonomicrometry), muscle–tendon force (using buckle transducers), and activity (using indwelling EMG). Muscle recordings were analysed from the stride just before to the second stride following the perturbation. The gastrocnemius exhibits altered force and work output in the perturbed and first recovery strides. Muscle work correlates strongly with leg posture at the time of ground contact. When the leg is more extended in the drop step, net gastrocnemius work decreases (−5.2 J kg−1versus control), and when the leg is more flexed in the step back up, it increases (+9.8 J kg−1versus control). The muscle's work output is inherently stabilising because it pushes the body back toward its pre-perturbation (level running) speed and leg posture. Gastrocnemius length and force return to level running means by the second stride following the perturbation. EMG intensity differs significantly from level running only in the first recovery stride following the perturbation, not within the perturbed stride. The findings suggest that intrinsic mechanical factors contribute substantially to the initial changes in muscle force and work. The statistical results suggest that a history-dependent effect, shortening deactivation, may be an important factor in the intrinsic mechanical changes, in addition to instantaneous force–velocity and force–length effects. This finding suggests the potential need to incorporate history-dependent muscle properties into neuromechanical simulations of running, particularly if high muscle strains are involved and stability characteristics are important. Future work should test whether a Hill or modified Hill type model provides adequate prediction in such conditions. Interpreted in light of previous studies on walking, the findings support the concept of speed-dependent roles of reflex feedback. PMID:19359369

Effects of different force fields on the structural character of α synuclein β-hairpin peptide (35-56) in aqueous environment.

PubMed

Kundu, Sangeeta

2018-02-01

The hallmark of Parkinson's disease (PD) is the intracellular protein aggregation forming Lewy Bodies (LB) and Lewy neuritis which comprise mostly of a protein, alpha synuclein (α-syn). Molecular dynamics (MD) simulation methods can augment experimental techniques to understand misfolding and aggregation pathways with atomistic resolution. The quality of MD simulations for proteins and peptides depends greatly on the accuracy of empirical force fields. The aim of this work is to investigate the effects of different force fields on the structural character of β hairpin fragment of α-syn (residues 35-56) peptide in aqueous solution. Six independent MD simulations are done in explicit solvent using, AMBER03, AMBER99SB, GROMOS96 43A1, GROMOS96 53A6, OPLS-AA, and CHARMM27 force fields with CMAP corrections. The performance of each force field is assessed from several structural parameters such as root mean square deviation (RMSD), root mean square fluctuation (RMSF), radius of gyration (Rg), solvent accessible surface area (SASA), formation of β-turn, the stability of folded β-hairpin structure, and the favourable conformations obtained for different force fields. In this study, CMAP correction of CHARMM27 force field is found to overestimate the helical conformation, while GROMOS96 53A6 is found to most successfully capture the conformational dynamics of α-syn β-hairpin fragment as elicited from NMR.

Adhesion mechanisms on solar glass: Effects of relative humidity, surface roughness, and particle shape and size

DOE PAGES

Moutinho, Helio R.; Jiang, Cun -Sheng; To, Bobby; ...

2017-07-27

To better understand and quantify soiling rates on solar panels, we are investigating the adhesion mechanisms between dust particles and solar glass. In this work, we report on two of the fundamental adhesion mechanisms: van der Waals and capillary adhesion forces. The adhesion was determined using force versus distance (F-z) measurements performed with an atomic force microscope (AFM). To emulate dust interacting with the front surface of a solar panel, we measured how oxidized AFM tips, SiO 2 glass spheres, and real dust particles adhered to actual solar glass. The van der Waals forces were evaluated by measurements performed withmore » zero relative humidity in a glove box, and the capillary forces were measured in a stable environment created inside the AFM enclosure with relative humidity values ranging from 18% to 80%. To simulate topographic features of the solar panels caused by factors such as cleaning and abrasion, we induced different degrees of surface roughness in the solar glass. As a result, we were able to 1) identify and quantify both the van der Waals and capillary forces, 2) establish the effects of surface roughness, relative humidity, and particle size on the adhesion mechanisms, and 3) compare adhesion forces between well-controlled particles (AFM tips and glass spheres) and real dust particles.« less

From Natural Variation to Optimal Policy? The Lucas Critique Meets Peer Effects. NBER Working Paper No. 16865

ERIC Educational Resources Information Center

Carrell, Scott E.; Sacerdote, Bruce I.; West, James E.

2011-01-01

We take cohorts of entering freshmen at the United States Air Force Academy and assign half to peer groups with the goal of maximizing the academic performance of the lowest ability students. Our assignment algorithm uses peer effects estimates from the observational data. We find a negative and significant treatment effect for the students we…

Locomotor Adaptation to an Asymmetric Force on the Human Pelvis Directed Along the Right Leg.

PubMed

Vashista, Vineet; Martelli, Dario; Agrawal, Sunil

2015-09-11

In this work, we study locomotor adaptation in healthy adults when an asymmetric force vector is applied to the pelvis directed along the right leg. A cable-driven Active Tethered Pelvic Assist Device (A-TPAD) is used to apply an external force on the pelvis, specific to a subject's gait pattern. The force vector is intended to provide external weight bearing during walking and modify the durations of limb supports. The motivation is to use this paradigm to improve weight bearing and stance phase symmetry in individuals with hemiparesis. An experiment with nine healthy subjects was conducted. The results show significant changes in the gait kinematics and kinetics while the healthy subjects developed temporal and spatial asymmetry in gait pattern in response to the applied force vector. This was followed by aftereffects once the applied force vector was removed. The adaptation to the applied force resulted in asymmetry in stance phase timing and lower limb muscle activity. We believe this paradigm, when extended to individuals with hemiparesis, can show improvements in weight bearing capability with positive effects on gait symmetry and walking speed.

The Labor Force Participation of Older Women: Retired? Working? Both?

ERIC Educational Resources Information Center

Hill, Elizabeth T.

2002-01-01

Noneconomic factors such as level of education, job flexibility in work hours, and physical stress appear to influence older women's labor force participation resulting in many retired women who are employed. Some women classified as retired work nearly as many hours as those employed, although many employed older women work part time. (Contains…

Aging Work Force Brings New Look at Teacher Retirement.

ERIC Educational Resources Information Center

Auriemma, Frank V.; And Others

1992-01-01

Higher salaries and improved working conditions have combined to make teaching a more attractive profession and to reduce teacher turnover rates. At the same time, however, the teaching work force has aged and faces problems in retirement programs. All levels of government should work with interested groups to find solutions to six major problems…

Soldier-relevant body borne loads increase knee joint contact force during a run-to-stop maneuver.

PubMed

Ramsay, John W; Hancock, Clifford L; O'Donovan, Meghan P; Brown, Tyler N

2016-12-08

The purpose of this study was to understand the effects of load carriage on human performance, specifically during a run-to-stop (RTS) task. Using OpenSim analysis tools, knee joint contact force, grounds reaction force, leg stiffness and lower extremity joint angles and moments were determined for nine male military personnel performing a RTS under three load configurations (light, ~6kg, medium, ~20kg, and heavy, ~40kg). Subject-based means for each biomechanical variable were submitted to repeated measures ANOVA to test the effects of load. During the RTS, body borne load significantly increased peak knee joint contact force by 1.2 BW (p<0.001) and peak vertical (p<0.001) and anterior-posterior (p=0.002) ground reaction forces by 0.6 BW and 0.3 BW, respectively. Body borne load also had a significant effect on hip (p=0.026) posture with the medium load and knee (p=0.046) posture with the heavy load. With the heavy load, participants exhibited a substantial, albeit non-significant increase in leg stiffness (p=0.073 and d=0.615). Increases in joint contact force exhibited during the RTS were primarily due to greater GRFs that impact the soldier with each incremental addition of body borne load. The stiff leg, extended knee and large braking force the soldiers exhibited with the heavy load suggests their injury risk may be greatest with that specific load configuration. Further work is needed to determine if the biomechanical profile exhibited with the heavy load configuration translates to unsafe shear forces at the knee joint and consequently, a higher likelihood of injury. Published by Elsevier Ltd.

Effect of Axial Force on the Performance of Micromachined Vibratory Rate Gyroscopes

PubMed Central

Hou, Zhanqiang; Xiao, Dingbang; Wu, Xuezhong; Dong, Peitao; Chen, Zhihua; Niu, Zhengyi; Zhang, Xu

2011-01-01

It is reported in the published literature that the resonant frequency of a silicon micromachined gyroscope decreases linearly with increasing temperature. However, when the axial force is considerable, the resonant frequency might increase as the temperature increases. The axial force is mainly induced by thermal stress due to the mismatch between the thermal expansion coefficients of the structure and substrate. In this paper, two types of micromachined suspended vibratory gyroscopes with slanted beams were proposed to evaluate the effect of the axial force. One type was suspended with a clamped-free (C-F) beam and the other one was suspended with a clamped-clamped (C-C) beam. Their drive modes are the bending of the slanted beam, and their sense modes are the torsion of the slanted beam. The relationships between the resonant frequencies of the two types were developed. The prototypes were packaged by vacuum under 0.1 mbar and an analytical solution for the axial force effect on the resonant frequency was obtained. The temperature dependent performances of the operated mode responses of the micromachined gyroscopes were measured. The experimental values of the temperature coefficients of resonant frequencies (TCF) due to axial force were 101.5 ppm/°C for the drive mode and 21.6 ppm/°C for the sense mode. The axial force has a great influence on the modal frequency of the micromachined gyroscopes suspended with a C-C beam, especially for the flexure mode. The quality factors of the operated modes decreased with increasing temperature, and changed drastically when the micromachined gyroscopes worked at higher temperatures. PMID:22346578

Spin dynamics of qqq wave function on light front in high momentum limit of QCD: Role of qqq force

NASA Astrophysics Data System (ADS)

Mitra, A. N.

2008-04-01

The contribution of a spin-rich qqq force (in conjunction with pairwise qq forces) to the analytical structure of the qqq wave function is worked out in the high momentum regime of QCD where the confining interaction may be ignored, so that the dominant effect is Coulombic. A distinctive feature of this study is that the spin-rich qqq force is generated by a ggg vertex (a genuine part of the QCD Lagrangian) wherein the 3 radiating gluon lines end on as many quark lines, giving rise to a (Mercedes-Benz type) Y-shaped diagram. The dynamics is that of a Salpeter-like equation (3D support for the kernel) formulated covariantly on the light front, a la Markov-Yukawa Transversality Principle (MYTP) which warrants a 2-way interconnection between the 3D and 4D Bethe-Salpeter (BSE) forms for 2 as well as 3 fermion quarks. With these ingredients, the differential equation for the 3D wave function ϕ receives well-defined contributions from the qq and qqq forces. In particular a negative eigenvalue of the spin operator iσ1 · σ2 × σ3 which is an integral part of the qqq force, causes a characteristic singularity in the differential equation, signalling the dynamical effect of a spin-rich qqq force not yet considered in the literature. The potentially crucial role of this interesting effect vis-a-vis the so-called 'spin anomaly' of the proton, is a subject of considerable physical interest.

Correlating steric hydration forces with water dynamics through surface force and diffusion NMR measurements in a lipid–DMSO–H2O system

PubMed Central

Schrader, Alex M.; Donaldson, Stephen H.; Song, Jinsuk; Cheng, Chi-Yuan; Lee, Dong Woog; Han, Songi; Israelachvili, Jacob N.

2015-01-01

Dimethyl sulfoxide (DMSO) is a common solvent and biological additive possessing well-known utility in cellular cryoprotection and lipid membrane permeabilization, but the governing mechanisms at membrane interfaces remain poorly understood. Many studies have focused on DMSO–lipid interactions and the subsequent effects on membrane-phase behavior, but explanations often rely on qualitative notions of DMSO-induced dehydration of lipid head groups. In this work, surface forces measurements between gel-phase dipalmitoylphosphatidylcholine membranes in DMSO–water mixtures quantify the hydration- and solvation-length scales with angstrom resolution as a function of DMSO concentration from 0 mol% to 20 mol%. DMSO causes a drastic decrease in the range of the steric hydration repulsion, leading to an increase in adhesion at a much-reduced intermembrane distance. Pulsed field gradient NMR of the phosphatidylcholine (PC) head group analogs, dimethyl phosphate and tetramethylammonium ions, shows that the ion hydrodynamic radius decreases with increasing DMSO concentration up to 10 mol% DMSO. The complementary measurements indicate that, at concentrations below 10 mol%, the primary effect of DMSO is to decrease the solvated volume of the PC head group and that, from 10 mol% to 20 mol%, DMSO acts to gradually collapse head groups down onto the surface and suppress their thermal motion. This work shows a connection between surface forces, head group conformation and dynamics, and surface water diffusion, with important implications for soft matter and colloidal systems. PMID:26261313

Study on Surface Depression of Ti-6Al-4V with Ultrahigh-Frequency Pulsed Gas Tungsten Arc Welding

NASA Astrophysics Data System (ADS)

Mingxuan, Yang; Zhou, Yang; Bojin, Qi

2015-08-01

Molten pool surface depression was observed with the arc welding process that was caused by arc pressure. It was supposed to have a significant effect on fluid in the molten pool that was important for the microstructure and joint properties. The impact of arc force was recognized as the reason for the surface depression during arc welding. The mathematical distribution of arc force was produced with the exponent and parabola models. Different models showed different concentrations and attenuations. The comparison between them was discussed with the simulation results. The volume of fluid method was picked up with the arc force distribution model. The surface depression was caused by the arc force. The geometry of the surface depression was discussed with liquid metal properties. The welding process was carried out with different pulsed frequencies. The results indicated the forced depression exists in molten pool and the geometry of depression was hugely due to the arc force distribution. The previous work calculated the depression in the center with force balance at one point. The other area of gas shielding was resistant by the reverse gravity from the feedback of liquid metal that was squeezed out. The article discusses the pressure effect with free deformation that allowed resistance of liquid and was easy to compare with different distributions. The curve profiles were studied with the arc force distributions, and exponent model was supposed to be more accurate to the as-weld condition.

Customizable Optical Force Sensor for Fast Prototyping and Cost-Effective Applications.

PubMed

Díez, Jorge A; Catalán, José M; Blanco, Andrea; García-Perez, José V; Badesa, Francisco J; Gacía-Aracil, Nicolás

2018-02-07

This paper presents the development of an optical force sensor architecture directed to prototyping and cost-effective applications, where the actual force requirements are still not well defined or the most suitable commercial technologies would highly increase the cost of the device. The working principle of this sensor consists of determining the displacement of a lens by measuring the distortion of a refracted light beam. This lens is attached to an elastic interface whose elastic constant is known, allowing the estimation of the force that disturbs the optical system. In order to satisfy the requirements of the design process in an inexpensive way, this sensor can be built by fast prototyping technologies and using non-optical grade elements. To deal with the imperfections of this kind of manufacturing procedures and materials, four fitting models are proposed to calibrate the implemented sensor. In order to validate the system, two different sensor implementations with measurement ranges of ±45 N and ±10 N are tested with the proposed models, comparing the resulting force estimation with respect to an industrial-grade load cell. Results show that all models can estimate the loads with an error of about 6% of the measurement range.

Customizable Optical Force Sensor for Fast Prototyping and Cost-Effective Applications

PubMed Central

Díez, Jorge A.; Catalán, José M.; Blanco, Andrea; García-Perez, José V.; Badesa, Francisco J.

2018-01-01

This paper presents the development of an optical force sensor architecture directed to prototyping and cost-effective applications, where the actual force requirements are still not well defined or the most suitable commercial technologies would highly increase the cost of the device. The working principle of this sensor consists of determining the displacement of a lens by measuring the distortion of a refracted light beam. This lens is attached to an elastic interface whose elastic constant is known, allowing the estimation of the force that disturbs the optical system. In order to satisfy the requirements of the design process in an inexpensive way, this sensor can be built by fast prototyping technologies and using non-optical grade elements. To deal with the imperfections of this kind of manufacturing procedures and materials, four fitting models are proposed to calibrate the implemented sensor. In order to validate the system, two different sensor implementations with measurement ranges of ±45 N and ±10 N are tested with the proposed models, comparing the resulting force estimation with respect to an industrial-grade load cell. Results show that all models can estimate the loads with an error of about 6% of the measurement range. PMID:29414861

First-principles study of pollutant molecules absorbed on polymeric adsorbents using the vdW-DF2 functional

NASA Astrophysics Data System (ADS)

Zhu, Jinguo; Wang, Yapeng; Tian, Ting; Zhang, Qianfan

2018-03-01

Polymeric adsorbents have been attracting increasing attention because of their favorable structrual properties and effectiveness of solving small molecules contaminants. However, due to the absence of deep insight into the adsorption mechanism of polymeric adsorbents, researches on new polymeric adsorbents can only be carried out by repeated experiments and tests, which is extremely inefficient. Therefore, investigating the adsorption process of polymeric adsorbents, especially the mechanism of adsorbing various air pollutant molecules by materials modelling and simulation, is of great significance. Here in this work, we systematically studied the adsorption mechanism by first-principles computation with van der Waals interaction. It demonstrates that the adsorption between them was pure physisorption originating from the hydrogen bond and intermolecular forces consisting of Keesom force, Debye force and London dispersion force. The proportions of these forces varied according to different adsorption systems. The adsorption effects were determined by the polymers’ dipole moment and polarizability. The adsorption performance of some polymers with special structures was also investigated to explore their possibility as potential adsorbents. The results of our simulation can provide some guidance for developing new polymeric adsorbents with better performance.

Youth Employment. Final Recommendations of the State Superintendent's Task Force.

ERIC Educational Resources Information Center

Wisconsin State Dept. of Public Instruction, Madison.

This report contains the final recommendations of the task force on youth employment for the state of Wisconsin. The task force was specifically charged with studying issues related to working teenagers, reviewing existing laws and regulations on child labor, and developing recommendations to ensure that when teenagers work, their jobs do not…

Labor Force

ERIC Educational Resources Information Center

Occupational Outlook Quarterly, 2010

2010-01-01

The labor force is the number of people aged 16 or older who are either working or looking for work. It does not include active-duty military personnel or institutionalized people, such as prison inmates. Quantifying this total supply of labor is a way of determining how big the economy can get. Labor force participation rates vary significantly…

The challenge of an aging work force: keeping older workers employed and employable.

PubMed

Rix, S E

1996-01-01

This article reviews labor-force trends and older-worker employment policies in Japan and the United States. Both countries have aging work forces, but Japan's labor force is and for some time has been older than that of the United States. Japan's Ministry of Labor began addressing older-worker issues over 30 years ago and in the ensuing years has promulgated numerous initiatives to extend working life. Mandatory retirement, however, remains both legal and common in Japan, yet labor-force participation rates are higher for older persons in that country than in the United States, where mandatory retirement is illegal. Japan's older-worker programs and policies clearly seem to have an impact on labor-force rates, although those rates are dropping among the elderly in Japan as well as in the United States. The transferability of these programs and policies to the United States is discussed.

Motivations for entry into sex work and HIV risk among mobile female sex workers in India.

PubMed

Saggurti, Niranjan; Verma, Ravi K; Halli, Shiva S; Swain, Suvakanta N; Singh, Rajendra; Modugu, Hanimi Reddy; Ramarao, Saumya; Mahapatra, Bidhubhusan; Jain, Anrudh K

2011-09-01

This paper assesses the reasons for entry into sex work and its association with HIV risk behaviours among mobile female sex workers (FSWs) in India. Data were collected from a cross-sectional survey conducted in 22 districts across four high HIV prevalence states in India during 2007-2008. Analyses were limited to 5498 eligible mobile FSWs. The reasons given by FSWs for entering sex work and associations with socio-demographic characteristics were assessed. Reported reasons for entering sex work include poor or deprived economic conditions; negative social circumstances in life; own choice; force by an external person; and family tradition. The results from multivariate analyses indicate that those FSWs who entered sex work due to poor economic conditions or negative social circumstances in life or force demonstrated elevated levels of current inconsistent condom use as well as in the past in comparison with those FSWs who reported entering sex work by choice or family tradition. This finding indicates the need for a careful assessment of the pre-entry contexts among HIV prevention interventions since these factors may continue to hinder the effectiveness of efforts to reduce the spread of HIV/AIDS in India and elsewhere.

United States Air Force Quality of Air Force Life Active Duty Air Force Personnel Survey: 1980 Quick Look Report

DTIC Science & Technology

1980-07-01

number) Quality of life Job satisfaction ABSTRACT (Continue on reverse tide If nece.’snry and Identify by block number) eport summarizes results of...following description! WORKS Doing work that is personally meaningful and important; pride in ay work) job satisfaction ) recognition for my efforts and...family (if married ) or from home end friends (if unmarried ). EXTREMELY UNDESIRABLE INDIFFERENT EXTREMELY DESIRABLE 68. A favorable attitude on the

The effect of informal care on work and wages.

PubMed

Van Houtven, Courtney Harold; Coe, Norma B; Skira, Meghan M

2013-01-01

Cross-sectional evidence in the United States finds that informal caregivers have less attachment to the labor force. The causal mechanism is unclear: do children who work less become informal caregivers, or are children who become caregivers working less? Using longitudinal data from the Health and Retirement Study, we identify the relationship between informal care and work in the United States, both on the intensive and extensive margins, and examine wage effects. We control for time-invariant individual heterogeneity; rule out or control for endogeneity; examine effects for men and women separately; and analyze heterogeneous effects by task and intensity. We find modest decreases-2.4 percentage points-in the likelihood of working for male caregivers providing personal care. Female chore caregivers, meanwhile, are more likely to be retired. For female care providers who remain working, we find evidence that they decrease work by 3-10hours per week and face a 3 percent lower wage than non-caregivers. We find little effect of caregiving on working men's hours or wages. These estimates suggest that the opportunity costs to informal care providers are important to consider when making policy recommendations about the design and funding of public long-term care programs. Published by Elsevier B.V.

Comparison of shoulder load during power-assisted and purely hand-rim wheelchair propulsion.

PubMed

Kloosterman, Marieke G M; Eising, Hilde; Schaake, Leendert; Buurke, Jaap H; Rietman, Johan S

2012-06-01

Repetitive forces and moments are among the work requirements of hand-rim wheelchair propulsion that are related to shoulder injuries. No previous research has been published about the influence of power-assisted wheelchair propulsion on these work requirements. The purpose of our study was therefore to determine the influence of power-assisted propulsion on shoulder biomechanics and muscle activation patterns. We also explored the theoretical framework for the effectiveness of power-assisted propulsion in preventing shoulder injuries by decreasing the work requirements of hand-rim wheelchair propulsion. Nine non-wheelchair users propelled a hand-rim wheelchair on a treadmill at 0.9 m/s. Shoulder biomechanics, and muscle activation patterns, were compared between propulsion with and without power-assist. Propulsion frequency did not differ significantly between the two conditions (Wilcoxon Signed Rank test/significance level/effect size:4/.314/-.34). During power-assisted propulsion we found significantly decreased maximum shoulder flexion and internal rotation angles (1/.015/-.81 and 0/.008/-.89) and decreased peak force on the rim (0/.008/-.89). This resulted in decreased shoulder flexion, adduction and internal rotation moments (2/.021/-.77; 0/.008/-.89 and 1/.011/-.85) and decreased forces at the shoulder in the posterior, superior and lateral directions (2/.021/-.77; 2/.008/-.89 and 2/.024/-.75). Muscle activation in the pectoralis major, posterior deltoid and triceps brachii was also decreased (2/.038/-.69; 1/.015/-.81 and 1/.021/-.77). Power-assist influenced the work requirements of hand-rim wheelchair propulsion by healthy subjects. It was primarily the kinetics at rim and shoulder which were influenced by power-assisted propulsion. Additional research with actual hand-rim wheelchair users is required before extrapolation to routine clinical practice. Copyright © 2011 Elsevier Ltd. All rights reserved.

The effect of cigarette smoke extract on thrombomodulin-thrombin binding: an atomic force microscopy study.

PubMed

Wei, Yujie; Zhang, Xuejie; Xu, Li; Yi, Shaoqiong; Li, Yi; Fang, Xiaohong; Liu, Huiliang

2012-10-01

Cigarette smoking is a well-known risk factor for cardiovascular disease. Smoking can cause vascular endothelial dysfunction and consequently trigger haemostatic activation and thrombosis. However, the mechanism of how smoking promotes thrombosis is not fully understood. Thrombosis is associated with the imbalance of the coagulant system due to endothelial dysfunction. As a vital anticoagulation cofactor, thrombomodulin (TM) located on the endothelial cell surface is able to regulate intravascular coagulation by binding to thrombin, and the binding results in thrombosis inhibition. This work focused on the effects of cigarette smoke extract (CSE) on TM-thrombin binding by atomic force microscopy (AFM) based single-molecule force spectroscopy. The results from both in vitro and live-cell experiments indicated that CSE could notably reduce the binding probability of TM and thrombin. This study provided a new approach and new evidence for studying the mechanism of thrombosis triggered by cigarette smoking.

Polymeric mechanical amplifiers of immune cytokine-mediated apoptosis

NASA Astrophysics Data System (ADS)

Mitchell, Michael J.; Webster, Jamie; Chung, Amanda; Guimarães, Pedro P. G.; Khan, Omar F.; Langer, Robert

2017-03-01

Physical forces affect tumour growth, progression and metastasis. Here, we develop polymeric mechanical amplifiers that exploit in vitro and in vivo physical forces to increase immune cytokine-mediated tumour cell apoptosis. Mechanical amplifiers, consisting of biodegradable polymeric particles tethered to the tumour cell surface via polyethylene glycol linkers, increase the apoptotic effect of an immune cytokine on tumour cells under fluid shear exposure by as much as 50% compared with treatment under static conditions. We show that targeted polymeric particles delivered to tumour cells in vivo amplify the apoptotic effect of a subsequent treatment of immune cytokine, reduce circulating tumour cells in blood and overall tumour cell burden by over 90% and reduce solid tumour growth in combination with the antioxidant resveratrol. The work introduces a potentially new application for a broad range of micro- and nanoparticles to maximize receptor-mediated signalling and function in the presence of physical forces.

Effect of particle inertia on fluid turbulence in gas-solid disperse flow

NASA Astrophysics Data System (ADS)

Mito, Yoichi

2016-11-01

The effect of particle inertia on the fluid turbulence in gas-solid disperse flow through a vertical channel has been examined by using a direct numerical simulation, to calculate the gas velocities seen by the particles, and a simplified non-stationary flow model, in which a uniform distribution of solid spheres of density ratio of 1000 are added into the fully-developed turbulent gas flow in an infinitely wide channel. The gas flow is driven downward with a constant pressure gradient. The frictional Reynolds number defined with the frictional velocity before the addition of particles, v0*, is 150. The feedback forces are calculated using a point force method. Particle diameters of 0.95, 1.3 and 1.9, which are made dimensionless with v0* and the kinematic viscosity, and volume fractions, ranging from 1 ×10-4 to 2 ×10-3 , in addition to the one-way coupling cases, are considered. Gravitational effect is not clearly seen where the fluid turbulence is damped by feedback effect. Gas flow rate increases with the decrease in particle inertia, that causes the increase in feedback force. Fluid turbulence decreases with the increase in particle inertia, that causes the increase in diffusivity of feedback force and of fluid turbulence. This work was supported by JSPS KAKENHI Grant Number 26420097.

The contribution of volume, technique, and load to single-repetition and total-repetition kinematics and kinetics in response to three loading schemes.

PubMed

Crewther, Blair T; Cronin, John; Keogh, Justin W L

2008-11-01

This study examined the effect of volume, technique, and load upon single-repetition and total-repetition kinematics and kinetics during three loading schemes. Eleven recreationally trained males each performed a power (8 sets of 6 repetitions at 45% of one-repetition maximum [1RM], 3-minute rest periods, explosive and ballistic movements), hypertrophy (10 sets of 10 repetitions at 75% 1RM, 2-minute rest periods, controlled movements), and maximal strength (6 sets of 4 repetitions at 88% 1RM, 4-minute rest periods, explosive intent) scheme involving squats. Examination of repetition data showed that load intensity (% 1RM) generally had a direct effect on forces, contraction times, impulses, and work (i.e., increasing with load), whereas power varied across loads (p < 0.001). However, total-repetition forces, contraction times, impulses, work, and power were all greater in the hypertrophy scheme (p < 0.001), because of the greater number of repetitions performed (volume) as well as lifting technique. No differences in total forces were found between the equal-volume power and maximal strength schemes, but the former did produce greater total contraction times, work, and power (p < 0.001), which may also be attributed to repetition and technique differences. Total impulses were the only variable greater in the maximal strength scheme (p < 0.001). Thus, the interaction of load, volume, and technique plays an important role in determining the mechanical responses (stimuli) afforded by these workouts. These findings may explain disparities cited within research, regarding the effectiveness of different loading strategies for hypertrophy, maximal strength, and power adaptation.

Three Dimensional Distribution of Sensitive Field and Stress Field Inversion of Force Sensitive Materials under Constant Current Excitation.

PubMed

Zhao, Shuanfeng; Liu, Min; Guo, Wei; Zhang, Chuanwei

2018-02-28

Force sensitive conductive composite materials are functional materials which can be used as the sensitive material of force sensors. However, the existing sensors only use one-dimensional electrical properties of force sensitive conductive materials. Even in tactile sensors, the measurement of contact pressure is achieved by large-scale arrays and the units of a large-scale array are also based on the one-dimensional electrical properties of force sensitive materials. The main contribution of this work is to study the three-dimensional electrical properties and the inversion method of three-dimensional stress field of a force sensitive material (conductive rubber), which pushes the application of force sensitive material from one dimensional to three-dimensional. First, the mathematical model of the conductive rubber current field distribution under a constant force is established by the effective medium theory, and the current field distribution model of conductive rubber with different geometry, conductive rubber content and conductive rubber relaxation parameters is deduced. Secondly, the inversion method of the three-dimensional stress field of conductive rubber is established, which provides a theoretical basis for the design of a new tactile sensor, three-dimensional stress field and space force based on force sensitive materials.

CAD-based strength analysis of EK-18 excavator bucket construction for mounting of anti-adhesive devices

NASA Astrophysics Data System (ADS)

Zenkov, S. A.; Lobanov, D. V.

2018-03-01

3D rigid-body model of a bucket of power shovel EK-18 was built using modern CAD-software. Tetrahedral grid with 10-node second-order elements was chosen, and the given model was imported to APM WinMachine - model preparation preprocessor for finite element analysis. The finite element model was based on the geometrical model, imported from KOMPAS-3D to APM Studio. Calculation of stressed-strained state of the bucket was carried out under the forces emerging while digging with “back hoe” equipment. Shift, deformation and tension charts were planned and the most and the least strained areas were pointed out. Wet coherent soil excavation deals with soil adhesion to working bodies of power shovels and leads to reduced performance. The performance decrease is caused by a reduction of useful bucket capacity and partial unloading, increased front resistance to cutting (digging) caused by wet soil adhesion to a working body, increased bucket entry resistance, increased idle time caused by necessity to clean working bodies. Also energy losses increase and quality of work drops because friction forces go up. Friction force occurs while digging and levelling account for 30…70 percent of total digging resistance while performance decreases 1.2…2 times and more. Vibrothermal exposure creates new technological effect which involves a wider humidity range of efficient application and a reduction of friction forces. Disintegrating adhesion bonds with heating requires less driving force from the vibrator. Vibration boosts up heating of the contact layer, which reduces thermal energy losses. However, the question of piezoelectric ceramic actuators location on the excavator bucket needs to be dealt with. The most suitable spots for mounting piezoelectric ceramic devices for reducing soil adhesion to the excavator bucket were defined. Their efficiency is derived from combined (vibrothermal) methods of exposure. Such devices eliminates soil adhesion to the bucket and increases efficiency of using power shovels with wet coherent soils.

Magnetic field effects on the vestibular system: calculation of the pressure on the cupula due to ionic current-induced Lorentz force.

PubMed

Antunes, A; Glover, P M; Li, Y; Mian, O S; Day, B L

2012-07-21

Large static magnetic fields may be employed in magnetic resonance imaging (MRI). At high magnetic field strengths (usually from about 3 T and above) it is possible for humans to perceive a number of effects. One such effect is mild vertigo. Recently, Roberts et al (2011 Current Biology 21 1635-40) proposed a Lorentz-force mechanism resulting from the ionic currents occurring naturally in the endolymph of the vestibular system. In the present work a more detailed calculation of the forces and resulting pressures in the vestibular system is carried out using a numerical model. Firstly, realistic 3D finite element conductivity and fluid maps of the utricle and a single semi-circular canal containing the current sources (dark cells) and sinks (hair cells) of the utricle and ampulla were constructed. Secondly, the electrical current densities in the fluid are calculated. Thirdly, the developed Lorentz force is used directly in the Navier-Stokes equation and the trans-cupular pressure is computed. Since the driving force field is relatively large in comparison with the advective acceleration, we demonstrate that it is possible to perform an approximation in the Navier-Stokes equations that reduces the problem to solving a simpler Poisson equation. This simplification allows rapid and easy calculation for many different directions of applied magnetic field. At 7 T a maximum cupula pressure difference of 1.6 mPa was calculated for the combined ampullar (0.7 µA) and utricular (3.31 µA) distributed current sources, assuming a hair-cell resting current of 100 pA per unit. These pressure values are up to an order of magnitude lower than those proposed by Roberts et al using a simplistic model and calculation, and are in good agreement with the estimated pressure values for nystagmus velocities in caloric experiments. This modeling work supports the hypothesis that the Lorentz force mechanism is a significant contributor to the perception of magnetic field induced vertigo.

Vertical drag force acting on intruders of different shapes in granular media

NASA Astrophysics Data System (ADS)

Zaidi, Ali Abbas; Müller, Christoph

2017-06-01

The penetration of large objects into granular media is encountered commonly both in nature (e.g. impacts of meteors and projectiles) and engineering applications (e.g. insertion of tractor blades into sand). The motion of the impacting intruder in granular media is resisted by a granular drag force. In this work, we assess the effect of intruder shape on the granular drag force using discrete element modelling (DEM). The following intruder shapes were modelled: spherical, conical, cylindrical and cubical. We observed that the drag force can be described well by a power-law relationship with intrusion depth, independent of the intruder shape. However, the exponent of the power-law expression increases with increasing "flatness" of the intruder's impacting surface due to an increasing fraction of the granular media affected by the impact of the intruder.

Retrospective on the construction and practice of a state-level emergency medical rescue team.

PubMed

Lei, Zhang; Haitao, Guo; Xin, Wang; Yundou, Wang

2014-10-01

For the past few years, disasters like earthquakes, landslides, mudslides, tsunamis, and traffic accidents have occurred with an ever-growing frequency, coverage, and intensity greatly beyond the expectation of the public. In order to respond effectively to disasters and to reduce casualties and property damage, countries around the world have invested more efforts in the theoretical study of emergency medicine and the construction of emergency medical rescue forces. Consequently, emergency medical rescue teams of all scales and types have come into being and have played significant roles in disaster response work. As the only state-level emergency medical rescue force from the Chinese People's Armed Police Forces, the force described here has developed, through continuous learning and practice, a characteristic mode in terms of grouping methods, equipment system construction, and training.

Limits on new forces coexisting with electromagnetism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kloor, H.; Fischbach, E.; Talmadge, C.

1994-02-15

We consider the limits arising from different electromagnetic systems on the existence of a possible new electromagnetic analogue of the fifth force. Although such a force may have no intrinsic connection to electromagnetism (or gravity), its effects could be manifested through various anomalies in electromagnetic systems, for appropriate values of the coupling strength and range. Our work generalizes that of Bartlett and Loegl (who considered the case of a massive vector field coexisting with massless electrodynamics) to encompass a broad class of phenomenological interactions mediated by both scalar and vector exchanges. By combining data from both gravitational and electromagnetic systems,more » one can eventually set limits on a new force whose range [lambda] extends from the subatomic scale ([lambda][approx]10[sup [minus]15] m) to the astrophysical scale ([lambda][approx]10[sup 12] m).« less

Job embeddedness factors and retention of nurses with 1 to 3 years of experience.

PubMed

Halfer, Diana

2011-10-01

An aging work force, predictions of job growth in health care, and an eventual economic recovery suggest that the current reprieve from the national nursing shortage is temporary. New graduate nurses are an important part of the work force and are needed to replace nurses who will retire in the next decade. Organizational leaders can address the forecasted work force demand by proactively investing in programs for workplace development and retention. Recent literature reports an increased focus on understanding the work experience and career support needed for new graduate nurses. Several studies report improvements in job satisfaction and retention after implementation of structured mentoring programs for new graduate nurses. However, despite successful transition programs, turnover for these same nurses after 1 to 3 years of organizational tenure remains high. Studying factors that contribute to retention and supporting careers beyond the first year of practice may have a significant effect on improving retention and will contribute new knowledge to the nursing literature. This study, undertaken at a Midwestern pediatric academic medical center, examined job factors and career development support that lead to retention of nurses with 1 to 3 years of experience. Understanding these issues may guide nursing leaders and staff development educators in investing in focused retention and career development plans during an economic recession. Copyright 2011, SLACK Incorporated.

Women and Work.

ERIC Educational Resources Information Center

Butler, Margaret; Swanson, Linda

1985-01-01

Examines changes in female labor force participation since 1950. Finds little difference currently between metro and nonmetro areas in propensity of women to work outside the home. Traces racial and age differences in labor force participation. Finds family situation and changing social expectations responsible for increase in working women. (LFL)

48 CFR 970.2270 - Unemployment compensation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the negotiation and administration of cost-reimbursement type contracts, that economical and practical... work force stability and the general outlook with respect to future work force stability; (v) In a...

L4-L5 compression and anterior/posterior joint shear forces in cabin attendants during the initial push/pull actions of airplane meal carts.

PubMed

Sandfeld, Jesper; Rosgaard, Christian; Jensen, Bente Rona

2014-07-01

The aim of the present study was to assess the acute low back load of cabin attendants during cart handling and to identify working situations which present the highest strain on the worker. In a setup, 17 cabin attendants (ten females and seven males) pushed, pulled and turned a 20 kg standard meal cart (L: 0.5m × W: 0.3 m × H: 0.92 m) loaded with extra 20 kg and 40 kg, respectively on two different surfaces (carpet and linoleum) and at three floor inclinations (-2°, 0° and +2°). Two force transducers were mounted as handles. Two-dimensional movement analysis was performed and a 4D WATBAK modelling tool was used to calculate the acute L4-L5 load. No working situations created loads greater than the accepted values for single exertions, however compression and anterior/posterior shear forces during pulling and turning were much higher when compared with pushing. There were significant effects of handling the cart on different floor types, at the varying inclinations and with different cart weights. Additionally, when external forces were reduced, the cabin attendants did not decrease push/pull force proportionally and thus the L4-L5 load did not decrease as much as expected. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Influence of structure of iron nanoparticles in aggregates on their magnetic properties

PubMed Central

2011-01-01

Zero-valent iron nanoparticles rapidly aggregate. One of the reasons is magnetic forces among the nanoparticles. Magnetic field around particles is caused by composition of the particles. Their core is formed from zero-valent iron, and shell is a layer of magnetite. The magnetic forces contribute to attractive forces among the nanoparticles and that leads to increasing of aggregation of the nanoparticles. This effect is undesirable for decreasing of remediation properties of iron particles and limited transport possibilities. The aggregation of iron nanoparticles was established for consequent processes: Brownian motion, sedimentation, velocity gradient of fluid around particles and electrostatic forces. In our previous work, an introduction of influence of magnetic forces among particles on the aggregation was presented. These forces have significant impact on the rate of aggregation. In this article, a numerical computation of magnetic forces between an aggregate and a nanoparticle and between two aggregates is shown. It is done for random position of nanoparticles in an aggregate and random or arranged directions of magnetic polarizations and for structured aggregates with arranged vectors of polarizations. Statistical computation by Monte Carlo is done, and range of dominant area of magnetic forces around particles is assessed. PMID:21917152

Can feedback analysis be used to uncover the physical origin of climate sensitivity and efficacy differences?

NASA Astrophysics Data System (ADS)

Rieger, Vanessa S.; Dietmüller, Simone; Ponater, Michael

2017-10-01

Different strengths and types of radiative forcings cause variations in the climate sensitivities and efficacies. To relate these changes to their physical origin, this study tests whether a feedback analysis is a suitable approach. For this end, we apply the partial radiative perturbation method. Combining the forward and backward calculation turns out to be indispensable to ensure the additivity of feedbacks and to yield a closed forcing-feedback-balance at top of the atmosphere. For a set of CO2-forced simulations, the climate sensitivity changes with increasing forcing. The albedo, cloud and combined water vapour and lapse rate feedback are found to be responsible for the variations in the climate sensitivity. An O3-forced simulation (induced by enhanced NOx and CO surface emissions) causes a smaller efficacy than a CO2-forced simulation with a similar magnitude of forcing. We find that the Planck, albedo and most likely the cloud feedback are responsible for this effect. Reducing the radiative forcing impedes the statistical separability of feedbacks. We additionally discuss formal inconsistencies between the common ways of comparing climate sensitivities and feedbacks. Moreover, methodical recommendations for future work are given.

Interior view to the south of computer work stations in ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Interior view to the south of computer work stations in front of elevated work area 1570 on left and elevated glassed in work area 1870 on right - Over-the-Horizon Backscatter Radar Network, Mountain Home Air Force Operations Building, On Desert Street at 9th Avenue Mountain Home Air Force Base, Mountain Home, Elmore County, ID

Effect of cannabis smoking on lung function and respiratory symptoms: a structured literature review

PubMed Central

Ribeiro, Luis IG; Ind, Philip W

2016-01-01

As cannabis use increases, physicians need to be familiar with the effects of both cannabis and tobacco on the lungs. However, there have been very few long-term studies of cannabis smoking, mostly due to legality issues and the confounding effects of tobacco. It was previously thought that cannabis and tobacco had similar long-term effects as both cause chronic bronchitis. However, recent large studies have shown that, instead of reducing forced expiratory volume in 1 s and forced vital capacity (FVC), marijuana smoking is associated with increased FVC. The cause of this is unclear, but acute bronchodilator and anti-inflammatory effects of cannabis may be relevant. Bullous lung disease, barotrauma and cannabis smoking have been recognised in case reports and small series. More work is needed to address the effects of cannabis on lung function, imaging and histological changes. PMID:27763599

Teleoperator comfort and psychometric stability: Criteria for limiting master-controller forces of operation and feedback during telemanipulation

NASA Technical Reports Server (NTRS)

Wiker, Steven F.; Hershkowitz, Elaine; Zik, John

1989-01-01

The following question is addressed: How much force should operators exert, or experience, when operating a telemanipulator master-controller for sustained periods without encountering significant fatigue and discomfort, and without loss of stability in psychometric perception of force. The need to minimize exertion demands to avoid fatigue is diametrically opposed by the need to present a wide range of force stimuli to enhance perception of applied or reflected forces. For 104 minutes subjects repetitiously performed a series of 15 s isometric pinch grasps; controlled at 5, 15, and 25 percent of their maximum voluntary strength. Cyclic pinch grasps were separated by rest intervals of 7.5 and 15 s. Upon completion of every 10 minute period, subjects interrupted grasping activities to gage the intensity of fatigue and discomfort in the hand and forearm using a cross-modal matching technique. A series of psychometric tests were then conducted to determine accuracy and stability in the subject's perception of force experienced. Results showed that onset of sensations of discomfort and fatigue were dependent upon the magnitude of grasp force, work/rest ratio, and progression of task. Declines in force magnitude estimation slopes, indicating a reduction in force perception sensitivity, occurred with increased grasp force when work/rest ratios were greater than 1.0. Specific recommendations for avoiding discomfort and shifts in force perception, by limiting pinch grasp force required for master-controller operation and range of force reflection or work/rest ratios, are provided.

DoD Influenza Surveillance and Vaccine Effectiveness

DTIC Science & Technology

2014-02-28

controls – No analyses by flu subtype (over 90% of flu samples were H1N1) 21 • Adjusted Estimates of Vaccine Effectiveness – Population: Service...DoD Influenza Surveillance and Vaccine Effectiveness Armed Forces Health Surveillance Center (AFHSC) Naval Health Research Center (NHRC) United... Vaccine Effectiveness 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK

Understanding work related musculoskeletal pain: does repetitive work cause stress symptoms?

PubMed

Bonde, J P; Mikkelsen, S; Andersen, J H; Fallentin, N; Baelum, J; Svendsen, S W; Thomsen, J F; Frost, P; Kaergaard, A

2005-01-01

Pain in the neck and upper extremity is reported with high frequency in repetitive work. Mechanical overload of soft tissues seems a plausible mechanism, but psychological factors have received considerable attention during the past decade. If psychological factors are important for development of regional pain in repetitive work, stress symptoms would likely be on the causal path. To examine whether objective measures of repetitive monotonous work are related to occurrence and development of stress symptoms. In 1994-95, 2033 unskilled workers with continuous repetitive work and 813 workers with varied work were enrolled. Measures of repetitiveness and force requirements were quantified using video observations to obtain individual exposure estimates. Stress symptoms were recorded at baseline and after approximately one, two, and three years by the Setterlind Stress Profile Inventory. Repetitive work, task cycle time, and quantified measures of repetitive upper extremity movements including force requirements were not related to occurrence of stress symptoms at baseline or development of stress symptoms during three years of follow up. The findings do not indicate that repetitive work is associated with stress symptoms, but small effects cannot be ruled out. Thus the results question the importance of mental stress mechanisms in the causation of regional pain related to repetitive work. However, the findings should be interpreted with caution because the stress inventory has not been validated against a gold standard.

Effects of work zone configurations and traffic density on performance variables and subjective workload.

PubMed

Shakouri, Mahmoud; Ikuma, Laura H; Aghazadeh, Fereydoun; Punniaraj, Karthy; Ishak, Sherif

2014-10-01

This paper investigates the effect of changing work zone configurations and traffic density on performance variables and subjective workload. Data regarding travel time, average speed, maximum percent braking force and location of lane changes were collected by using a full size driving simulator. The NASA-TLX was used to measure self-reported workload ratings during the driving task. Conventional lane merge (CLM) and joint lane merge (JLM) were modeled in a driving simulator, and thirty participants (seven female and 23 male), navigated through the two configurations with two levels of traffic density. The mean maximum braking forces was 34% lower in the JLM configuration, and drivers going through the JLM configuration remained in the closed lane longer. However, no significant differences in speed were found between the two merge configurations. The analysis of self-reported workload ratings show that participants reported 15.3% lower total workload when driving through the JLM. In conclusion, the implemented changes in the JLM make it a more favorable merge configuration in both high and low traffic densities in terms of optimizing traffic flow by increasing the time and distance cars use both lanes, and in terms of improving safety due to lower braking forces and lower reported workload. Copyright © 2014 Elsevier Ltd. All rights reserved.

Societal Consequences of the g Factor in Employment.

ERIC Educational Resources Information Center

Gottfredson, Linda S.

1986-01-01

Reviews and rebuts seven common arguments that intelligence (g) is of little or no practical importance in employment. Illustrates in several ways the profound effect that differences in intelligence in a work force may have on the structure and functioning of whole societies. (Author/ABB)

23 CFR 230.411 - Guidance for conducting reviews.

Code of Federal Regulations, 2011 CFR

2011-04-01

... to conduct the home office review. (d) Employment of women. Executive Order 11246, as amended... responsibility of the Compliance Specialist to ensure that contractors provide women full participation in their work forces. (e) Effect of exclusive referral agreements. (1) The OFCCP has established the following...

23 CFR 230.411 - Guidance for conducting reviews.

Code of Federal Regulations, 2010 CFR

2010-04-01

... to conduct the home office review. (d) Employment of women. Executive Order 11246, as amended... responsibility of the Compliance Specialist to ensure that contractors provide women full participation in their work forces. (e) Effect of exclusive referral agreements. (1) The OFCCP has established the following...

Turning the Aircraft Carrier.

ERIC Educational Resources Information Center

Kraack, Thomas

2003-01-01

Describes how one company developed an organizational structure and system of governance to ensure that strategy and work force enablement are locked in. Discusses the following principles for trainers: understanding the business, directing the effects learning has on business results, and managing relationships with key decision makers. (JOW)

Enhancing the effects of diversity awareness training : a review of the research literature.

DOT National Transportation Integrated Search

1995-03-01

The projected changes in the demographic makeup of the work force were primary influences in the spread of diversity awareness training in the private and public sector. One approach to training aims at changing personal attitudes and values to effec...

Lifelong Learning NCES Task Force: Final Report, Volume I. Working Paper Series.

ERIC Educational Resources Information Center

Binkley, Marilyn; Hudson, Lisa; Knepper, Paula; Kolstad, Andy; Stowe, Peter; Wirt, John

In September 1998, the National Center for Education Statistics (NCES) established a 1-year task force to review the NCES's role concerning lifelong learning. The eight-member task force established a working definition of lifelong learning ("a process or system through which individuals are able and willing to learn at all stages of life,…

Extrinsic Motivation as Correlates of Work Attitude of the Nigerian Police Force: Implications for Counselling

ERIC Educational Resources Information Center

Igun, Sylvester Nosakhare

2008-01-01

The study examined Extrinsic motivation as correlates of work attitude of the Nigeria Police Force and its implications for counselling. 300 Police personnel were selected by random sampling technique from six departments that make up police force Headquarters, Abuja. The personnel were selected from each department using simple sampling…

Exploring Work and Development Options to Reduce Early Labour Force Exit of Mature Aged Australians

ERIC Educational Resources Information Center

Pillay, Hitendra; Kelly, Kathy; Tones, Megan

2008-01-01

Early labour force exit is a significant challenge associated with the ageing workforce in Australia and many other developed countries. A reduction and increased flexibility of work hours has been suggested to improve labour force participation of the mature aged cohort. However, little is known about mature aged workers' aspirations for…

Results of a national survey indicating information technology skills needed by nurses at time of entry into the work force.

PubMed

McCannon, Melinda; O'Neal, Pamela V

2003-08-01

A national survey was conducted to determine the information technology skills nurse administrators consider critical for new nurses entering the work force. The sample consisted of 2,000 randomly selected members of the American Organization of Nurse Executives. Seven hundred fifty-two usable questionnaires were returned, for a response rate of 38%. The questionnaire used a 5-point Likert scale and consisted of 17 items that assessed various technology skills and demographic information. The questionnaire was developed and pilot tested with content experts to establish content validity. Descriptive analysis of the data revealed that using e-mail effectively, operating basic Windows applications, and searching databases were critical information technology skills. The most critical information technology skill involved knowing nursing-specific software, such as bedside charting and computer-activated medication dispensers. To effectively prepare nursing students with technology skills needed at the time of entry into practice, nursing faculty need to incorporate information technology skills into undergraduate nursing curricula.

Thermally Activated Composite with Two-Way and Multi-Shape Memory Effects

PubMed Central

Basit, Abdul; L’Hostis, Gildas; Pac, Marie José; Durand, Bernard

2013-01-01

The use of shape memory polymer composites is growing rapidly in smart structure applications. In this work, an active asymmetric composite called “controlled behavior composite material (CBCM)” is used as shape memory polymer composite. The programming and the corresponding initial fixity of the composite structure is obtained during a bending test, by heating CBCM above thermal glass transition temperature of the used Epoxy polymer. The shape memory properties of these composites are investigated by a bending test. Three types of recoveries are conducted, two classical recovery tests: unconstrained recovery and constrained recovery, and a new test of partial recovery under load. During recovery, high recovery displacement and force are produced that enables the composite to perform strong two-way actuations along with multi-shape memory effect. The recovery force confirms full recovery with two-way actuation even under a high load. This unique property of CBCM is characterized by the recovered mechanical work. PMID:28788316

Workforce 2000. A Bibliography.

ERIC Educational Resources Information Center

Florida State Univ., Tallahassee. Center for Instructional Development and Services.

This bibliography contains citations locating information about the future U.S. work force. Because of demographic, economic, and technological developments, significant changes are predicted in both the nature of work and the composition of the work force by the year 2000. Projections, viewpoints, and suggested responses to these changes from…

Effects of Shift Work on the Postural and Psychomotor Performance of Night Workers

PubMed Central

Narciso, Fernanda Veruska; Barela, José A.; Aguiar, Stefane A.; Carvalho, Adriana N. S.; Tufik, Sergio; de Mello, Marco Túlio

2016-01-01

The purpose of the study was to investigate the effects of shift work on the psychomotor and postural performance of night workers. The study included 20 polysomnography technicians working schedule of 12-h night shift by 36-h off. On the first day of protocol, the body mass and height were measured, and an actigraph was placed on the wrist of each participant. On the second day of protocol, sleepiness by Karolinska Sleepiness Scale, postural control by force platform (30 seconds) and psychomotor performance by Psychomotor Vigilance Task (10 minutes) were measured before and after 12-h night work. Results showed that after 12-h night work, sleepiness increased by 59% (p<0.001), postural control variables increased by 9% (p = 0.048), and 14% (p = 0.006). Mean reaction time, and the number of lapses of attention increased by 13% (p = 0.006) and 425% (p = 0.015), respectively, but the mean reciprocal reaction time decreased by 7%. In addition, there were correlations between sleepiness and postural control variables with opened eyes (r = 0.616, 95% confidence interval [CI] = 0.361–0.815; r = 0.538; 95% CI = 0.280–0.748) and closed eyes (r = 0.557; 95% CI = 0.304–0.764, r = 0497; 95% CI = 0.325–0.715) and a pronounced effect of sleepiness on postural sway (R2 = 0.393; 95% CI = 0.001–0.03). Therefore, 12-h night work system and sleepiness showed a negative impact in postural and psychomotor vigilance performance of night workers. As unexpected, the force platform was feasibility to detect sleepiness in this population, underscoring the possibility of using this method in the workplace to prevent occupational injuries and accidents. PMID:27115868

Effects of Shift Work on the Postural and Psychomotor Performance of Night Workers.

PubMed

Narciso, Fernanda Veruska; Barela, José A; Aguiar, Stefane A; Carvalho, Adriana N S; Tufik, Sergio; de Mello, Marco Túlio

2016-01-01

The purpose of the study was to investigate the effects of shift work on the psychomotor and postural performance of night workers. The study included 20 polysomnography technicians working schedule of 12-h night shift by 36-h off. On the first day of protocol, the body mass and height were measured, and an actigraph was placed on the wrist of each participant. On the second day of protocol, sleepiness by Karolinska Sleepiness Scale, postural control by force platform (30 seconds) and psychomotor performance by Psychomotor Vigilance Task (10 minutes) were measured before and after 12-h night work. Results showed that after 12-h night work, sleepiness increased by 59% (p<0.001), postural control variables increased by 9% (p = 0.048), and 14% (p = 0.006). Mean reaction time, and the number of lapses of attention increased by 13% (p = 0.006) and 425% (p = 0.015), respectively, but the mean reciprocal reaction time decreased by 7%. In addition, there were correlations between sleepiness and postural control variables with opened eyes (r = 0.616, 95% confidence interval [CI] = 0.361-0.815; r = 0.538; 95% CI = 0.280-0.748) and closed eyes (r = 0.557; 95% CI = 0.304-0.764, r = 0497; 95% CI = 0.325-0.715) and a pronounced effect of sleepiness on postural sway (R2 = 0.393; 95% CI = 0.001-0.03). Therefore, 12-h night work system and sleepiness showed a negative impact in postural and psychomotor vigilance performance of night workers. As unexpected, the force platform was feasibility to detect sleepiness in this population, underscoring the possibility of using this method in the workplace to prevent occupational injuries and accidents.

The Idyllic Workplace

NASA Technical Reports Server (NTRS)

Schoenfelder, Tony E.

2002-01-01

How many of us have worked in organizations where the discipline was so rigid and unyielding that it would send even a Marine Corps Drill Instructor screaming into the night? How many of us have worked in organizations where sightings of senior management were sporadic and rare, and any other interactions were by appointment only? Or, how many of us have worked in organizations where your role, absent specific direction, was to be seldom seen and rarely heard? And how many of us have worked in organizations where seemingly light itself was not permitted to escape without the acquiescence and approval of the director? Sadly, there are organizations that embody some of these conditions, and the resultant adverse effects on employee productivity, creativity and morale are profound. But what if you could work in an organization in which there was little hierarchy, where rank and seniority played no part, where there were no closed meetings or doors, where everyone knows what was expected of them, and where creativity was not only tolerated but encouraged and celebrated? Was there ever such a place? There was, and it was known as NASA's Space Station Task Force. I was fortunate enough to work there for a time, and I would like to tell you how this organization with few apparent rules led to incredibly high levels of employee satisfaction and fulfillment, and yielded work products of enduring quality. On May 20, 1982, NASA Administrator James M. Beggs established the Space Station Task Force under the direction of John D. Hodge. The Task Force was charged with the responsibility for "the development of the programmatic aspects of a Space Station as they evolve, including mission analysis, requirements definition and program management," and was authorized to draw on Space Station activities at the NASA Program Offices and Field Centers. No additional conditions or directions were provided. Hodge knew that in order to accomplish the job he had been given, he was going to have to obtain the services of the "best and the brightest" and facilitate the unleashing of the full force of their creative capabilities. In order to avoid the stultifying effects of a typical hierarchical organization, he set up a loosely structured, horizontal organization with only one supervisor of record - himself. He populated this organization with detailees from Headquarters, the field Centers and the Jet Propulsion Lab, thereby assuring himself of the political and technical expertise with which to deal with Congress and the bureaucracy, and conduct the required engineering studies and analyses.

What is the prevalence of and associations with forced labour experiences among male migrants from Dolakha, Nepal? Findings from a cross-sectional study of returnee migrants.

PubMed

Mak, Joelle; Abramsky, Tanya; Sijapati, Bandita; Kiss, Ligia; Zimmerman, Cathy

2017-08-11

Growing numbers of people are migrating outside their country for work, and many experience precarious conditions, which have been linked to poor physical and mental health. While international dialogue on human trafficking, forced labour and slavery increases, prevalence data of such experiences remain limited. Men from Dolakha, Nepal, who had ever migrated outside of Nepal for work were interviewed on their experiences, from predeparture to return (n=194). Forced labour was assessed among those who returned within the past 10 years (n=140) using the International Labour Organization's forced labour dimensions: (1) unfree recruitment ; (2) work and life under duress ; and (3) impossibility to leave employer . Forced labour is positive if any one of the dimensions is positive. Participants had worked in India (34%), Malaysia (34%) and the Gulf Cooperation Council countries (29%), working in factories (29%), as labourers/porters (15%) or in skilled employment (12%). Among more recent returnees (n=140), 44% experienced unfree recruitment , 71% work and life under duress and 14% impossibility to leave employer . Overall, 73% experienced forced labour during their most recent labour migration.Forced labour was more prevalent among those who had taken loans for their migration (PR 1.23) and slightly less prevalent among those who had migrated more than once (PR 0.87); however the proportion of those who experienced forced labour was still high (67%). Age, destination and duration of stay were associated with only certain dimensions of forced labour. Forced labour experiences were common during recruitment and at destination. Migrant workers need better advice on assessing agencies and brokers, and on accessing services at destinations. As labour migration from Nepal is not likely to reduce in the near future, interventions and policies at both source and destinations need to better address the challenges migrants face so they can achieve safer outcomes. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

The Effect of the Traveling Magnetic Field (TMF) on the Buoyancy-Induced Convection in the Vertical Bridgman growth of Germanium

NASA Technical Reports Server (NTRS)

Yesilyurt, S.; Motakef, S.; Grugel, R.; Mazuruk, K.

2003-01-01

A traveling magnetic field (TMF) is created by means of applying out-of-phase currents to a number of coils. When applied to a conducting melt inside a cylindrical container, the TMF induces a Lorentz force that acts in the meridional directions (radial and axial), unlike the application of a rotating magnetic field (RMF), which creates a force in the azimuthal direction. In this work, we present a computational study of the TMF and its application to the Bridgman growth of the Ge. To quantify the effect of the TMF on the solid-melt interface, we use the maximum (magnitude-wise) tangential shear at the interface.

Work addiction and presenteeism: The buffering role of managerial support.

PubMed

Mazzetti, Greta; Vignoli, Michela; Schaufeli, Wilmar B; Guglielmi, Dina

2017-08-08

The current study examined the mediating effect of presenteeism and moderating effect of managerial support in the relation between workaholism and work-family conflict. A sample of 1065 white-collar employees from an Italian company filled in an online survey and hypotheses were tested using a bootstrapping procedure. Results showed that presenteeism mediated the association between workaholism and work-family conflict. Moreover, the mediating effect of presenteeism was moderated by managerial support: for employees reporting lower levels of support workaholism was stronger related to presenteeism than for those experiencing higher support. Presenteeism, in turn, was related to greater levels of work-family conflict. The present study sheds light into the protective role played by managerial support in preventing workaholic employees from forcing themselves to attend work also when feeling sick. Accordingly, early intervention aimed at buffering the negative association between workaholism and work-family conflict should focus on training managers to develop supportive leadership skills. © 2017 International Union of Psychological Science.

Biocompatilibity-related surface characteristics of oxidized NiTi.

PubMed

Danilov, Anatoli; Tuukkanen, Tuomas; Tuukkanen, Juha; Jämsä, Timo

2007-09-15

In the present study, we examined the effect of NiTi oxidation on material surface characteristics related to biocompatibility. Correspondence between electron work function (EWF) and adhesive force predicted by electron theory of adsorption as well as the effect of surface mechanical stress on the adhesive force were studied on the nonoxidized and oxidized at 350, 450, and 600 degrees C NiTi alloy for medical application. The adhesive force generated by the material surface towards the drops of alpha-minimal essential medium (alpha-MEM) was used as a characteristic of NiTi adsorption properties. The study showed that variations in EWF and mechanical stress caused by surface treatment were accompanied by variations in adhesive force. NiTi oxidation at all temperatures used gave rise to decrease in adhesive force and surface stress values in comparison to the nonoxidized state. In contrary, the EWF value revealed increase under the same condition. Variations in surface oxide layer thickness and its phase composition were also followed. The important role of oxide crystallite size in EWF values within the range of crystallite dimensions typical for NiTi surface oxide as an instrument for the fine regulation of NiTi adsorption properties was demonstrated. The comparative oxidation of pure titanium and NiTi showed that the effect of Ni on the EWF value of NiTi surface oxide is negligible. Copyright 2007 Wiley Periodicals, Inc.

Characteristics of a Strongly-Pulsed Non-Premixed Jet Flame in Cross-flow

NASA Astrophysics Data System (ADS)

Gamba, Mirko; Clemens, Noel T.; Ezekoye, Ofodike A.

2006-11-01

The effects of large-amplitude, high-frequency harmonic forcing of turbulent nonpremixed hydrogen/methane jet flames in cross-flow (JFICF) are investigated experimentally. Flame lengths, penetration lengths, and mixing characteristics are studied using flame luminosity imaging, planar laser Mie scattering visualization and particle image velocimetry. Mean jet Reynolds numbers of 1,600 and 3,250 (peak Re ˜2,500--6,500) with corresponding mean momentum flux ratios, r, of 1.9 and 3.7 (peak r ˜2.6--8.3) are considered. Forcing frequencies of 100 Hz and 300 Hz with amplitudes of ˜60%--300% are investigated. Consistent with previous work, a drastic decrease in flame length and soot emission, an increase in flame penetration and an improved jet fuel/cross-flow air mixing are observed for the larger forcing amplitude cases. Partial pre-mixing induced by near-field reverse flow, near-field vortex/vortex interaction and large-scale stirring, rendered stronger by large forcing amplitudes and frequencies, are thought to play a key role on the observed effects.

GCM Simulations of Titan's Paleoclimate

NASA Astrophysics Data System (ADS)

Lora, Juan M.; Lunine, Jonathan; Russell, Joellen; Hayes, Alexander

2014-11-01

The hemispheric asymmetry observed in the distribution of Titan's lakes and seas has been suggested to be the result of asymmetric seasonal forcing, where a relative moistening of the north occurs in the current epoch due to its longer and less intense summers. General circulation models (GCMs) of present-day Titan have also shown that the atmosphere transports methane away from the equator. In this work, we use a Titan GCM to investigate the effects that changes in Titan's effective orbital parameters have had on its climate in recent geologic history. The simulations show that the climate is relatively insensitive to changes in orbital parameters, with persistently dry low latitudes and wet polar regions. The amount of surface methane that builds up over either pole depends on the insolation distribution, confirming the influence of orbital forcing on the distribution of surface liquids. The evolution of the orbital forcing implies that the surface reservoir must be transported on timescales of ~30 kyr, in which case the asymmetry reverses with a period of ~125 kyr. Otherwise, the orbital forcing is insufficient for generating the observed dichotomy.

[Demography and labor shortage. Future challenges of labor market policy].

PubMed

Fuchs, J

2013-03-01

For demographic reasons, the German labor force will decrease dramatically and it will be much older on average. However, labor demand, especially for qualified workers, is expected to remain high. This paper focuses on the possibilities of expanding the labor force by increasing the participation rates of women and older persons. Herein, the change in the labor force is decomposed with respect to population and labor participation and, moreover, the effects of higher participation rates are simulated. The decomposition and simulation scenarios are based on data published by the Institute for Employment Research. The analysis clearly reveals that the effect of a considerably higher labor participation of women and older workers will disappear over time when the working-age population shrinks more and more. In addition, individuals who are currently unemployed or out of the labor force are not skilled enough. Since it seems difficult to get more qualified workers in the short and even in the medium term, improving the conditions for women and older people to take up jobs should be tackled soon. This includes investments in education and health care.

Battle Staff Training and Synchronization in Light Infantry Battalions and Task Forces

DTIC Science & Technology

1991-12-01

Institute for the Behavioral and Social Sciences Fort Benning Field Unit (ARI-Benning) joined the Training Research Laboratory’s Determinants of Effective ...and unforgiving. The effective management and manipulation of stressors in a continuous operations environment, along with an efficient and consistent...an organizational effectiveness model grounded in the General Systems Theory model. An extensive body of work was reviewed, but two authors stand out

JPRS Report China

DTIC Science & Technology

1988-11-23

general trend, in recent years inflation of consumption funds has not yet spent its full force in its effect on commodity prices. For some considerable...launch policy and theory studies on the administration of the financial market and institutions to guide the financial work more effectively . To...the effective study of Chinese, on the one hand, and the right of the national minorities to use their own spoken and written language, on the other

Intrinsic embedded sensors for polymeric mechatronics: flexure and force sensing.

PubMed

Jentoft, Leif P; Dollar, Aaron M; Wagner, Christopher R; Howe, Robert D

2014-02-25

While polymeric fabrication processes, including recent advances in additive manufacturing, have revolutionized manufacturing, little work has been done on effective sensing elements compatible with and embedded within polymeric structures. In this paper, we describe the development and evaluation of two important sensing modalities for embedding in polymeric mechatronic and robotic mechanisms: multi-axis flexure joint angle sensing utilizing IR phototransistors, and a small (12 mm), three-axis force sensing via embedded silicon strain gages with similar performance characteristics as an equally sized metal element based sensor.

Load Bearing Equipment for Bone and Muscle Project

NASA Technical Reports Server (NTRS)

Terrier, Douglas; Clayton, Ronald G.; Shackelford, Linda

2015-01-01

Axial skeletal loads coupled with muscle torque forces around joints maintain bone. Astronauts working in pairs to exercise can provide high eccentric loads for each other that are most effective. A prototype of load bearing equipment that will allow astronauts to perform exercises using each other for counter force generation in a controlled fashion and provide eccentric overload is proposed. A frame and attachments that can be rapidly assembled for use and easily stored will demonstrate feasibility of a design that can be adapted for ISS testing and Orion use.

Political influences on greenhouse gas emissions from US states.

PubMed

Dietz, Thomas; Frank, Kenneth A; Whitley, Cameron T; Kelly, Jennifer; Kelly, Rachel

2015-07-07

Starting at least in the 1970s, empirical work suggested that demographic (population) and economic (affluence) forces are the key drivers of anthropogenic stress on the environment. We evaluate the extent to which politics attenuates the effects of economic and demographic factors on environmental outcomes by examining variation in CO2 emissions across US states and within states over time. We find that demographic and economic forces can in part be offset by politics supportive of the environment--increases in emissions over time are lower in states that elect legislators with strong environmental records.

Intrinsic Embedded Sensors for Polymeric Mechatronics: Flexure and Force Sensing

PubMed Central

Jentoft, Leif P.; Dollar, Aaron M.; Wagner, Christopher R.; Howe, Robert D.

2014-01-01

While polymeric fabrication processes, including recent advances in additive manufacturing, have revolutionized manufacturing, little work has been done on effective sensing elements compatible with and embedded within polymeric structures. In this paper, we describe the development and evaluation of two important sensing modalities for embedding in polymeric mechatronic and robotic mechanisms: multi-axis flexure joint angle sensing utilizing IR phototransistors, and a small (12 mm), three-axis force sensing via embedded silicon strain gages with similar performance characteristics as an equally sized metal element based sensor. PMID:24573310

Environmental Assessment for the Construction of a Phase I Surface Deployment and Distribution Command Transportation Command Consolidation Facility and a Phase I & II Mobility Air Force Logistics Support Center

DTIC Science & Technology

2006-04-01

Interagency Working Group on Environmental Justice defines adverse as “having deleterious effects on human health or the environment that is significant...Drinking water for Scott AFB is provided by the Illinois-American Water Company and no potable water wells are located on the installation. As a result...Environment Scott Air Force Base, Illinois April 2006 Illinois-American Water Company uses the Mississippi River as its source of drinking water and

Explicit control of adaptive automation under different levels of environmental stress.

PubMed

Sauer, Jürgen; Kao, Chung-Shan; Wastell, David; Nickel, Peter

2011-08-01

This article examines the effectiveness of three different forms of explicit control of adaptive automation under low- and high-stress conditions, operationalised by different levels of noise. In total, 60 participants were assigned to one of three types of automation design (free, prompted and forced choice). They were trained for 4 h on a highly automated simulation of a process control environment, called AutoCAMS. This was followed by a 4-h testing session under noise exposure and quiet conditions. Measures of performance, psychophysiology and subjective reactions were taken. The results showed that all three modes of explicit control of adaptive automation modes were able to attenuate the negative effects of noise. This was partly due to the fact that operators opted for higher levels of automation under noise. It also emerged that forced choice showed marginal advantages over the two other automation modes. Statement of Relevance: This work is relevant to the design of adaptive automation since it emphasises the need to consider the impact of work-related stressors during task completion. During the presence of stressors, different forms of operator support through automation may be required than under more favourable working conditions.

Customization, control, and characterization of a commercial haptic device for high-fidelity rendering of weak forces.

PubMed

Gurari, Netta; Baud-Bovy, Gabriel

2014-09-30

The emergence of commercial haptic devices offers new research opportunities to enhance our understanding of the human sensory-motor system. Yet, commercial device capabilities have limitations which need to be addressed. This paper describes the customization of a commercial force feedback device for displaying forces with a precision that exceeds the human force perception threshold. The device was outfitted with a multi-axis force sensor and closed-loop controlled to improve its transparency. Additionally, two force sensing resistors were attached to the device to measure grip force. Force errors were modeled in the frequency- and time-domain to identify contributions from the mass, viscous friction, and Coulomb friction during open- and closed-loop control. The effect of user interaction on system stability was assessed in the context of a user study which aimed to measure force perceptual thresholds. Findings based on 15 participants demonstrate that the system maintains stability when rendering forces ranging from 0-0.20 N, with an average maximum absolute force error of 0.041 ± 0.013 N. Modeling the force errors revealed that Coulomb friction and inertia were the main contributors to force distortions during respectively slow and fast motions. Existing commercial force feedback devices cannot render forces with the required precision for certain testing scenarios. Building on existing robotics work, this paper shows how a device can be customized to make it reliable for studying the perception of weak forces. The customized and closed-loop controlled device is suitable for measuring force perceptual thresholds. Copyright © 2014 Elsevier B.V. All rights reserved.

Work/Family Conflicts: Policy Implications.

ERIC Educational Resources Information Center

Baker, Maureen

In the past 20 years, the percentage of married women in the Canadian labor force has risen dramatically. Despite women's increased participation in the labor force, child care and housework are still largely done by women. While the difficulty of combining work and family responsibilities can result in work/family conflicts, a variety of…

77 FR 25150 - GPS Satellite Simulator Working Group; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-27

...-1600 (Pacific Standard Time). This meeting notice is to inform the public that the Global Positioning... DEPARTMENT OF DEFENSE Department of the Air Force GPS Satellite Simulator Working Group; Notice of Meeting AGENCY: The United States Air Force, DoD. ACTION: Amending GPS Simulator Working group Meeting...

77 FR 70421 - GPS Satellite Simulator Control Working Group Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-26

... DEPARTMENT OF DEFENSE Department of the Air Force GPS Satellite Simulator Control Working Group Meeting AGENCY: Space and Missile Systems Center, Global Positioning Systems (GPS) Directorate, Department... Control Working Group (SSCWG) meeting on 14 December 2012 from 0900-1600 PST at Los Angeles Air Force Base...

78 FR 63459 - GPS Satellite Simulator Control Working Group Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-24

... DEPARTMENT OF DEFENSE Air Force GPS Satellite Simulator Control Working Group Meeting AGENCY... and DoD contractors, that the GPS Directorate will host a GPS Satellite Simulator Control Working Group (SSCWG) meeting on 1 November 2013 from 0900-1300 PST at Los Angeles Air Force Base. The purpose...

Determinants explaining the variability of hand-transmitted vibration emissions from two different work tasks: grinding and cutting using angle grinders.

PubMed

Liljelind, Ingrid; Pettersson, Hans; Nilsson, Leif; Wahlström, Jens; Toomingas, Allan; Lundström, Ronnie; Burström, Lage

2013-10-01

There are numerous factors including physical, biomechanical, and individual that influence exposure to hand-transmitted vibration (HTV) and cause variability in the exposure measurements. Knowledge of exposure variability and determinants of exposure could be used to improve working conditions. We performed a quasi-experimental study, where operators performed routine work tasks in order to obtain estimates of the variance components and to evaluate the effect of determinants, such as machine-wheel combinations and individual operator characteristics. Two pre-defined simulated work tasks were performed by 11 operators: removal of a weld puddle of mild steel and cutting of a square steel pipe. In both tasks, four angle grinders were used, two running on compressed air and two electrically driven. Two brands of both grinding and cutting wheels were used. Each operator performed both tasks twice in a random order with each grinder and wheel and the time to complete each task was recorded. Vibration emission values were collected and the wheel wear was measured as loss of weight. Operators' characteristics collected were as follows: age, body height and weight, length and volume of their hands, maximum hand grip force, and length of work experience with grinding machines (years). The tasks were also performed by one operator who used four machines of the same brand. Mixed and random effects models were used in the statistical evaluation. The statistical evaluation was performed for grinding and cutting separately and we used a measure referring to the sum of the 1-s r.m.s. average frequency-weighted acceleration over time for completing the work task (a(sa)). Within each work task, there was a significant effect as a result of the determinants 'the machine used', 'wheel wear', and 'time taken to complete the task'. For cutting, 'the brand of wheel' used also had a significant effect. More than 90% of the inherent variability in the data was explained by the determinants. The two electrically powered machines had a mean a(sa) that was 2.6 times higher than the two air-driven machines. For cutting, the effect of the brand of wheel on a(sa) was ~0.1 times. The a(sa) increased both with increasing wheel wear and with time taken to complete the work task. However, there were also a number of interaction effects which, to a minor extent, modified the a(sa). Only a minor part (1%) of the total variability was attributed to the operator: for cutting, the volume of the hands, maximum grip force, and body weight were significant, while for grinding, it was the maximum grip force. There was no clear difference in a(sa) between the four copies of the same brand of each machine. By including determinants that were attributed to the brand of both machine and wheel used as well as the time taken to complete the work task, we were able to explain >90% of the variability. The dominating determinant was the brand of the machine. Little variability was found between operators, indicating that the overall effect as due to the operator was small.

Impacts of the Convention on Long-range Transboundary Air Pollution on air quality in Europe.

PubMed

Bull, Keith; Johansson, Matti; Krzyzanowski, Michal

2008-01-01

The Convention on Long-range Transboundary Air Pollution has been one of the main ways of protecting the environment in Europe from air pollution. This convention has successfully bridged different political systems even through times of political change, and is a prime example of what can be achieved through intergovernmental cooperation. Through creating an effective framework for controlling and reducing the damage to human health and the environment from transboundary air pollution, this convention has proved successful. This article considers the development of the convention and its work on adverse air pollution effects, in particular on activities related to quantifying effects on human health as carried out by the convention's joint (with WHO) Task Force on the Health Effects of Air Pollution (Task Force on Health), and concludes with some indications of the convention's future priorities.

Managing professional work: three models of control for health organizations.

PubMed Central

Scott, W R

1982-01-01

Three arrangements for structuring the work of professional participants in professional organizations are described, contrasted and evaluated. Arguments are illustrated by application to the organization of physicians within hospitals. The primary rationale, the support structures that have fostered its development, the key structural features and the advantages and disadvantages of each arrangement are described. The effect on these arrangements of structures and forces external to any particular professional organization is emphasized. PMID:6749761

U.S. Air Force Research Laboratory's Need for Flow Physics and Control With Applications Involving Aero-Optics and Weapon Bay Cavities

NASA Technical Reports Server (NTRS)

Schmit, Ryan

2010-01-01

To develop New Flow Control Techniques: a) Knowledge of the Flow Physics with and without control. b) How does Flow Control Effect Flow Physics (What Works to Optimize the Design?). c) Energy or Work Efficiency of the Control Technique (Cost - Risk - Benefit Analysis). d) Supportability, e.g. (size of equipment, computational power, power supply) (Allows Designer to include Flow Control in Plans).

Aerospace Expeditionary Force Implementation and the Effect on Team Cohesion

DTIC Science & Technology

2002-03-01

quickly load UTCs during real world conflicts, deployments, or exercises. The TPFDD is the Joint Operation Planning and Execution System data base... system in mission capable status in an efficeint manner. Time is saved by not having to establish work/personal relationships and new work peocesses...there wasn’t enough time for the system to process backfills for shortfalls that were, in reality, not shortfalls at all but a rainbow package. While

Navy Information Dominance, the Battle of Midway, and the Joint Force Commander: It Worked Then, It Needs to Work Now

DTIC Science & Technology

2013-05-19

cyberspace, is putting increased emphasis on the need for the Joint Force Commander to employ his force to achieve Information Dominance . The information... Information Dominance is to assist in achieving Decision Superiority, Assured Command and Control, Battlespace Awareness, and Integrated Fires. Navy... Information Dominance aims to use information in cyberspace as a way and means in warfare -- as a battery in the Joint Force Commander’s arsenal. The

Intersections of Stigma, Mental Health, and Sex Work: How Canadian Men Engaged in Sex Work Navigate and Resist Stigma to Protect Their Mental Health.

PubMed

Jiao, Sunny; Bungay, Vicky

2018-05-01

Men engaged in sex work experience significant stigma that can have devastating effects for their mental health. Little is known about how male sex workers experience stigma and its effects on mental health or their strategies to prevent its effects in the Canadian context. This study examined the interrelationships between stigma and mental health among 33 Canadian indoor, male sex workers with a specific goal of understanding how stigma affected men's mental health and their protective strategies to mitigate against its effects. Men experienced significant enacted stigma that negatively affected their social supports and ability to develop and maintain noncommercial, romantic relationships. Men navigated stigma by avoidance and resisting internalization. Strategy effectiveness to promote mental health varied based on men's perspectives of sex work as a career versus a forced source of income. Programming to promote men's mental health must take into consideration men's diverse strategies and serve to build social supports.

Development of a novel precision instrument for high-resolution simultaneous normal and shear force measurements between small planar samples

NASA Astrophysics Data System (ADS)

Lundstrom, Troy; Clark, William; Jalili, Nader

2017-05-01

In the design and development of end effector pads for silicon wafer handling robots, it is imperative that the static friction/adhesion force properties of the pads with respect to a variety of planar surfaces be characterized. In this work, the overall design, calibration, and data acquisition procedure of an instrument developed for performing these measurements on small (<10 mm × 10 mm) planar samples is presented. This device was used to perform adhesion/maximum shear force measurements on polydimethylsiloxane, a silicon wafer, and custom carbon nanotubes forest surfaces. The device was successfully able to measure an effective, mean profile adhesion force of 715 μN between a silicon wafer and a polydimethylsiloxane (2.768 × 10-6 m2) sample. In addition, a nonlinear maximum shear over normal force relationship was also measured between custom carbon nanotubes forest and the silicon wafer surfaces. The maximum shear over a normal force coefficient was found to decrease with increasing initial normal force. Currently, there are numerous devices for measuring normal/shear forces at the nano/micro- and macroscales; however, this device allows for the consistent measurement of these same types of forces on components with surface dimensions ranging from 0.1 mm to 10 mm.

Breaking the Time Barrier in Kelvin Probe Force Microscopy: Fast Free Force Reconstruction Using the G-Mode Platform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collins, Liam; Ahmadi, Mahshid; Wu, Ting

The atomic force microscope (AFM) offers unparalleled insight into structure and material functionality across nanometer length scales. However, the spatial resolution afforded by the AFM tip is counterpoised by slow detection speeds compared to other common microscopy techniques (e.g. optical, scanning electron microscopy etc.). In this work, we develop an AFM imaging approach allowing ultrafast reconstruction of the tip-sample forces having ~2 orders of magnitude higher time resolution than standard detection methods. Fast free force recovery (F3R) overcomes the widely-viewed temporal bottleneck in AFM, i.e. the mechanical bandwidth of the cantilever, enabling time-resolved imaging at sub-bandwidth speeds. We demonstrate quantitativemore » recovery of electrostatic forces with ~10 µs temporal resolution, free from cantilever ring-down effects. We further apply the F3R method to Kelvin probe force microscopy (KPFM) measurements. F3R-KPFM is an open loop imaging approach (i.e. no bias feedback), allowing ultrafast surface potential measurements (e.g. < 20 µs) to be performed at regular KPFM scan speeds. F3R-KPFM is demonstrated for exploration of ion migration in organometallic halide perovskites materials and shown to allow spatio-temporal imaging of positively charged ion migration under applied electric field, as well as subsequent formation of accumulated charges at the perovskite/electrode interface. In this work we demonstrate quantitative F3R-KPFM measurements – however, we fully expect the F3R approach to be valid for all modes of non-contact AFM operation, including non-invasive probing of ultrafast electrical and magnetic dynamics.« less

Breaking the Time Barrier in Kelvin Probe Force Microscopy: Fast Free Force Reconstruction Using the G-Mode Platform

DOE PAGES

Collins, Liam; Ahmadi, Mahshid; Wu, Ting; ...

2017-08-06

The atomic force microscope (AFM) offers unparalleled insight into structure and material functionality across nanometer length scales. However, the spatial resolution afforded by the AFM tip is counterpoised by slow detection speeds compared to other common microscopy techniques (e.g. optical, scanning electron microscopy etc.). In this work, we develop an AFM imaging approach allowing ultrafast reconstruction of the tip-sample forces having ~2 orders of magnitude higher time resolution than standard detection methods. Fast free force recovery (F3R) overcomes the widely-viewed temporal bottleneck in AFM, i.e. the mechanical bandwidth of the cantilever, enabling time-resolved imaging at sub-bandwidth speeds. We demonstrate quantitativemore » recovery of electrostatic forces with ~10 µs temporal resolution, free from cantilever ring-down effects. We further apply the F3R method to Kelvin probe force microscopy (KPFM) measurements. F3R-KPFM is an open loop imaging approach (i.e. no bias feedback), allowing ultrafast surface potential measurements (e.g. < 20 µs) to be performed at regular KPFM scan speeds. F3R-KPFM is demonstrated for exploration of ion migration in organometallic halide perovskites materials and shown to allow spatio-temporal imaging of positively charged ion migration under applied electric field, as well as subsequent formation of accumulated charges at the perovskite/electrode interface. In this work we demonstrate quantitative F3R-KPFM measurements – however, we fully expect the F3R approach to be valid for all modes of non-contact AFM operation, including non-invasive probing of ultrafast electrical and magnetic dynamics.« less

Jeopardy not bonus status for African American women in the work force: why does the myth of advantage persist?

PubMed

Sanchez-Hucles, J V

1997-10-01

African American women in the United States have a long history of employment outside of their homes. Their experiences are unique from other groups of majority and minority men and women due to the interaction of race, gender, and class. Despite long-standing and continuing struggles against discrimination, harassment, low pay, tokenism, and stereotypes, a myth that African American women enjoy a bonus or advantaged status in the work force has developed and persisted. In this article, Black women's work force experiences are examined from a social constructionist framework, misperceptions of Black women are critiqued, explanations are developed that explain the unique status of African American women and recommendations are proposed to eradicate the discrimination and marginal status that Black women have endured in the work force.

Get a Life? The Impact of the European Working Time Directive: The Case of UK Senior Doctors.

PubMed

Dolton, Peter J; Kidd, Michael P; Fooken, Jonas

2015-10-01

This paper seeks to identify the effect of the implementation of the European Working Time Directive on the working hours of UK doctors. The Labour Force Survey is used to compare the working hours of doctors with a variety of control groups before and after the implementation of the directive. The controls include those unconstrained by the directive and doctor counterparts working in Europe. We use differences-in-differences and matching methods to estimate the impact of this natural experiment, distinguishing between the anticipation and enactment of the European Working Time Directive. We find that the legislation reduced the hours of senior doctors by around 8 hours in total including the component attributable to anticipation effects and allowing for (exogenously set) rising wages. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

The effect of the electronic medical record on nurses' work.

PubMed

Robles, Jane

2009-01-01

The electronic medical record (EMR) is a workplace reality for most nurses. Its advantages include a single consolidated record for each person; capacity for data interfaces and alerts; improved interdisciplinary communication; and evidence-based decision support. EMRs can add to work complexity, by forcing better documentation of previously unrecorded data and/or because of poor design. Well-designed and well-implemented computerized provider order entry (CPOE) systems can streamline nurses' work. Generational differences in acceptance of and facility with EMRs can be addressed through open, healthy communication.

Transonic and supersonic ground effect aerodynamics

NASA Astrophysics Data System (ADS)

Doig, G.

2014-08-01

A review of recent and historical work in the field of transonic and supersonic ground effect aerodynamics has been conducted, focussing on applied research on wings and aircraft, present and future ground transportation, projectiles, rocket sleds and other related bodies which travel in close ground proximity in the compressible regime. Methods for ground testing are described and evaluated, noting that wind tunnel testing is best performed with a symmetry model in the absence of a moving ground; sled or rail testing is ultimately preferable, though considerably more expensive. Findings are reported on shock-related ground influence on aerodynamic forces and moments in and accelerating through the transonic regime - where force reversals and the early onset of local supersonic flow is prevalent - as well as more predictable behaviours in fully supersonic to hypersonic ground effect flows.

Systems approach used in the Gas Centrifuge Enrichment Plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rooks, W.A. Jr.

A requirement exists for effective and efficient transfer of technical knowledge from the design engineering team to the production work force. Performance-Based Training (PBT) is a systematic approach to the design, development, and implementation of technical training. This approach has been successfully used by the US Armed Forces, industry, and other organizations. The advantages of the PBT approach are: cost-effectiveness (lowest life-cycle training cost), learning effectiveness, reduced implementation time, and ease of administration. The PBT process comprises five distinctive and rigorous phases: Analysis of Job Performance, Design of Instructional Strategy, Development of Training Materials and Instructional Media, Validation of Materialsmore » and Media, and Implementation of the Instructional Program. Examples from the Gas Centrifuge Enrichment Plant (GCEP) are used to illustrate the application of PBT.« less

Solvent effect on the vibrational spectra of Carvedilol.

PubMed

Billes, Ferenc; Pataki, Hajnalka; Unsalan, Ozan; Mikosch, Hans; Vajna, Balázs; Marosi, György

2012-09-01

Carvedilol (CRV) is an important medicament for heart arrhythmia. The aim of this work was the interpretation of its vibrational spectra with consideration on the solvent effect. Infrared and Raman spectra were recorded in solid state as well in solution. The experimental spectra were evaluated using DFT quantum chemical calculations computing the optimized structure, atomic net charges, vibrational frequencies and force constants. The same calculations were done for the molecule in DMSO and aqueous solutions applying the PCM method. The calculated force constants were scaled to the experimentally observed solid state frequencies. The characters of the vibrational modes were determined by their potential energy distributions. Solvent effects on the molecular properties were interpreted. Based on these results vibrational spectra were simulated. Copyright © 2012 Elsevier B.V. All rights reserved.

Psychological, social, and mechanical work exposures and disability retirement: a prospective registry study.

PubMed

Emberland, Jan S; Nielsen, Morten Birkeland; Knardahl, Stein

2017-01-10

Relations between several occupational psychological and social factors and disability retirement remain largely unexplored. Knowledge of which specific aspects of the work environment that affect risk of disability is a prerequisite for the success of organizational interventions aiming to prevent premature work force exit. The objective of the present study was to determine contributions to registered disability retirement by a broad range of psychological and social work exposures while taking into account effects of mechanical exposure. Written consent was obtained from 13 012 employees (96 organizations) representing a wide range of occupations, to link their survey responses to data from the Norwegian national registry of disability compensation. Median follow-up time was 5.8 years. To determine effects of self-reported work exposures on risk of disability retirement hazard ratios (HR) and 99% confidence intervals (99% CI) were calculated with Cox regression analysis. Effects of sex, age group, skill level, sickness absence in the last three years, and work exposures estimated to be confounders were accounted for. Post hoc stratification by sex was conducted to explore if identified predictors affected risk of disability retirement differently in men compared to women. Contributors to higher risk of disability retirement were "role conflict" (high level HR 1.55 99% CI 1.07 to 2.24) and "physical workload" (high level HR 1.93 99% CI 1.39 to 2.68). Contributors to lower risk of disability retirement were "positive challenge" (high level HR 0.56 99% CI 0.34 to 0.93), "fair leadership" (high level HR 0.56 99% CI 0.39 to 0.81), and "control over work intensity" (high level HR 0.62, 99% CI 0.47 to 0.82). Direction of effects was not dependent on sex in any of the five identified predictors. Several specific psychological and social work factors are independent contributors to risk of disability retirement. In order to prevent premature work force exit workplace interventions should consider targeting the predictors identified by the present study.

Examining the "WorkFORCE"™ Assessment for Job Fit and Core Capabilities of "FACETS"™. Research Report. ETS RR-14-32

ERIC Educational Resources Information Center

Naemi, Bobby; Seybert, Jacob; Robbins, Steven; Kyllonen, Patrick

2014-01-01

This report introduces the "WorkFORCE"™ Assessment for Job Fit, a personality assessment utilizing the "FACETS"™ core capability, which is based on innovations in forced-choice assessment and computer adaptive testing. The instrument is derived from the fivefactor model (FFM) of personality and encompasses a broad spectrum of…

What Works: Air Pollution Solutions. Report No. 1.

ERIC Educational Resources Information Center

Malaspina, Mark; And Others

This report profiles 69 initiatives and programs from across the country that are effectively reducing smog, air toxics, and chemicals that destroy the ozone layer. Problem solving strategies range from community pressure forcing reduction of industrial emissions, to municipal governments promoting transportation alternatives, to adoption of tough…

Internet Links for Science Education: Student-Scientist Partnerships.

ERIC Educational Resources Information Center

Cohen, Karen C., Ed.

This volume focuses on Student-Scientist Partnerships (SSPs) and illustrates the workings and effectiveness of this new paradigm and growing force in science education. The chapters are: chapter 1, "Student-Scientist Partnerships: Shrewd Maneuvers" (Robert F. Tinker); chapter 2, "The GLOBE Program: A Model for International Environmental…

Gender Differences in NATO Anthropometry and the Implication for Protective Equipment

DTIC Science & Technology

2008-09-01

National Research Council 2800 Q Street Wright-Patterson AFB OH 45433-7947 Kathleen M. Robinette Biomechanics Branch Biosciences and Protection...Air Force Research Laboratory Human Effectiveness Directorate Biosciences and Protection Division Biomechanics ...BARRY REEDER, Work Unit Manager MARK M. HOFFMAN, Deputy Chief Biomechanics

Vocational Education and Productivity.

ERIC Educational Resources Information Center

Watson, Robert, Jr.

Vocational education can contribute to an improved United States productivity by producing an effective work force. People together with technology are two major factors in improving productivity, and they must be integrated. Industry is in the forefront of the efforts to improve productivity. It has encouraged management in long-range strategic…

The Responsive University: Restructuring for High Performance.

ERIC Educational Resources Information Center

Tierney, William G., Ed.

This book describes how colleges and universities might respond more effectively to changing social, demographic, and political forces. An introductory chapter, "On the Road to Recovery and Renewal: Reinventing Academe" (William G. Tierney), advocates reorienting basic work structures and designing more creative organizations. In "Listening to the…

Low-resistive penetration in granular media

NASA Astrophysics Data System (ADS)

Darbois Texier, Baptiste; Ibarra, Alejandro; Melo, Fransisco

The quasi-static immersion of an intruder into a granular assembly requires a force that is several orders of magnitude larger than necessary in fluids under similar conditions. This occurs as a result of the progressive formation of a network composed of force chains, which simultaneously increase in size with intruder penetration. The present work shows that the resisting force for the immersion of an intruder into a granular material can be reduced by an order of magnitude with mechanical vibrations of small amplitude (A = 10 μm) and low frequency (f = 50-200 Hz). The effect of the vibrations characteristics and the intruder geometry on the drop of the resistive force were inspected experimentally. Thanks to flow visualizations, it has been shown that vibrations induce a local convection into the granular media leading to the modification of the network of force chains. Moreover, scaling arguments are developed in order to rationalize our observations and to predict under which circumstances the resistive force is reduced. Finally, the use of such a phenomenon in the animal kingdom and the technological world will be discussed.

The effects of work-related and individual factors on the Work Ability Index: a systematic review.

PubMed

van den Berg, T I J; Elders, L A M; de Zwart, B C H; Burdorf, A

2009-04-01

This paper systematically reviews the scientific literature on the effects of individual and work-related factors on the Work Ability Index (WAI). Studies on work ability published from 1985 to 2006 were identified through a structured search in PubMed, and Web of Science. Studies were included if the WAI was used as measure of work ability and if quantitative information was presented on determinants of work ability. In total, 20 studies were included with 14 cross-sectional studies and six longitudinal studies. Factors associated with poor work ability, as defined by WAI, were lack of leisure-time vigorous physical activity, poor musculoskeletal capacity, older age, obesity, high mental work demands, lack of autonomy, poor physical work environment, and high physical work load. The WAI is associated with individual characteristics, lifestyle, demands at work, and physical condition. This multifactorial nature of work ability should be taken into account in health promotion programmes aimed at maintaining and promoting the participation of the labour force and improvement of the performance at work.

Trends in the Danish work environment in 1990-2000 and their associations with labor-force changes.

PubMed

Burr, Hermann; Bjorner, Jakob B; Kristensen, Tage S; Tüchsen, Finn; Bach, Elsa

2003-08-01

The aims of this study were (i) to describe the trends in the work environment in 1990-2000 among employees in Denmark and (ii) to establish whether these trends were attributable to labor-force changes. The split-panel design of the Danish Work Environment Cohort Study includes interviews with three cross-sections of 6067, 5454, and 5404 employees aged 18-59 years, each representative of the total Danish labor force in 1990, 1995 and 2000. In the cross-sections, the participation rate decreased over the period (90% in 1990, 80% in 1995, 76% in 2000). The relative differences in participation due to gender, age, and region did not change noticeably. Jobs with decreasing prevalence were clerks, cleaners, textile workers, and military personnel. Jobs with increasing prevalence were academics, computer professionals, and managers. Intense computer use, long workhours, and noise exposure increased. Job insecurity, part-time work, kneeling work posture, low job control, and skin contact with cleaning agents decreased. Labor-force changes fully explained the decline in low job control and skin contact to cleaning agents and half of the increase in long workhours, but not the other work environment changes. The work environment of Danish employees improved from 1990 to 2000, except for increases in long workhours and noise exposure. From a specific work environment intervention point of view, the development has been less encouraging because declines in low job control, as well as skin contact to cleaning agents, were explained by labor-force changes.

Effect of Cutting Parameters on Thrust Force and Surface Roughness in Drilling of Al-2219/B4C/Gr Metal Matrix Composites

NASA Astrophysics Data System (ADS)

Ravindranath, V. M.; Basavarajappa, G. S. Shiva Shankar S.; Suresh, R.

2016-09-01

In aluminium matrix composites, reinforcement of hard ceramic particle present inside the matrix which causes tool wear, high cutting forces and poor surface finish during machining. This paper focuses on effect of cutting parameters on thrust force, surface roughness and burr height during drilling of MMCs. In the present work, discuss the influence of spindle speed and feed rate on drilling the pure base alloy (Al-2219), mono composite (Al- 2219+8% B4C) and hybrid composite (Al-2219+8%B4C+3%Gr). The composites were fabricated using liquid metallurgy route. The drilling experiments were conducted by CNC machine with TiN coated HSS tool, M42 (Cobalt grade) and carbide tools at various spindle speeds and feed rates. The thrust force, surface roughness and burr height of the drilled hole were investigated in mono composite and hybrid composite containing graphite particles, the experimental results show that the feed rate has more influence on thrust force and surface roughness. Lesser thrust force and discontinuous chips were produced during machining of hybrid composites when compared with mono and base alloy during drilling process. It is due to solid lubricant property of graphite which reduces the lesser thrust force, burr height and lower surface roughness. When machining with Carbide tool at low feed and high speeds good surface finish was obtained compared to other two types of cutting tool materials.

Pregnant women in the workplace: distinguishing between normal and abnormal physiologic changes.

PubMed

Draper, London

2006-05-01

The Bureau of Labor Statistics reported in 2001 that 51% of married women return to the work force before their children are 1 year old (Rojjanasrirat, 2004). Women's roles in the United States are rapidly changing, and the workplace environment is also changing to meet the added demands of women in the work force. Many women assimilate the multiple roles of wife, mother, and working professional into a cohesive unit; however, this is often difficult. Occupational health nurses play a vital role advocating for women in the work force. A critical area of advocacy (and education) focuses on providing necessary support to pregnant employees.

Effects of Vibrations on Metal Forming Process: Analytical Approach and Finite Element Simulations

NASA Astrophysics Data System (ADS)

Armaghan, Khan; Christophe, Giraud-Audine; Gabriel, Abba; Régis, Bigot

2011-01-01

Vibration assisted forming is one of the most recent and beneficial technique used to improve forming process. Effects of vibration on metal forming processes can be attributed to two causes. First, the volume effect links lowering of yield stress with the influence of vibration on the dislocation movement. Second, the surface effect explains lowering of the effective coefficient of friction by periodic reduction contact area. This work is related to vibration assisted forming process in viscoplastic domain. Impact of change in vibration waveform has been analyzed. For this purpose, two analytical models have been developed for two different types of vibration waveforms (sinusoidal and triangular). These models were developed on the basis of Slice method that is used to find out the required forming force for the process. Final relationships show that application of triangular waveform in forming process is more beneficial as compare to sinusoidal vibrations in terms of reduced forming force. Finite Element Method (FEM) based simulations were performed using Forge2008®and these confirmed the results of analytical models. The ratio of vibration speed to upper die speed is a critical factor in the reduction of the forming force.

The work of titin protein folding as a major driver in muscle contraction

PubMed Central

Eckels, Edward C.; Tapia-Rojo, Rafael; Rivas-Pardo, Jamie Andrés; Fernández, Julio M.

2018-01-01

Single molecule atomic force microscopy and magnetic tweezers experiments have demonstrated that titin Ig domains are capable of folding against a pulling force, generating mechanical work which exceeds that produced by a myosin motor. We hypothesize that upon muscle activation, formation of actomyosin crossbridges reduces the force on titin causing entropic recoil of the titin polymer and triggering the folding of the titin Ig domains. In the physiological force range of 4–15 pN under which titin operates in muscle, the folding contraction of a single Ig domain can generate 200% of the work of entropic recoil, and occurs at forces which exceed the maximum stalling force of single myosin motors. Thus titin operates like a mechanical battery storing elastic energy efficiently by unfolding Ig domains, and delivering the charge back by folding when the motors are activated during a contraction. We advance the hypothesis that titin folding and myosin activation act as inextricable partners during muscle contraction. PMID:29433413

Valuing our differences. How to manage a culturally diverse work force.

PubMed

Veninga, R L

1994-12-01

How can we become aware of cultural blind spots that keep us from understanding one another? To adequately prepare for the new work force, healthcare organizations must establish work force diversity goals. Of course, goals by themselves will not empower minority workers. And if goals are perceived as "window dressing," resentment builds. Most organizations claim their hiring practices are not biased. One way to ensure that your hiring practices are unbiased is to ask important questions: Does the ethnic makeup of our work force resemble that of the community? If not, what can be done to strengthen our affirmative action programs? In a multicultural work force, misunderstandings are bound to arise because human behavior is conditioned by cultural factors. One way for an organization to identify problems that are culturally based is for supervisors and subordinates to meet informally to ensure that the organization is maximizing the minority worker's talents. Climate surveys and exit interviews are two other frequently used methods. Cultural diversity training programs can also make a difference in an organization. Some training programs help participants learn how culture influences the way we communicate. Knowledge of the cultural basis of how we interact is one factor in building bridges of understanding.

Knee extensor dynamics in the volleyball approach jump: the influence of patellar tendinopathy.

PubMed

Sorenson, Shawn C; Arya, Shruti; Souza, Richard B; Pollard, Christine D; Salem, George J; Kulig, Kornelia

2010-09-01

Controlled laboratory study using a cross-sectional design. To evaluate knee joint dynamics in elite volleyball players with and without a history of patellar tendinopathy, focusing on mechanical energy absorption and generation. We hypothesized that tendinopathy would be associated withreduced net joint work and net joint power. Patellar tendinopathy is a common, debilitating injury affecting competitive volleyball players. Thirteen elite male players with and without a history of patellar tendinopathy (mean ± SD age, 27 ± 7 years) performed maximum-effort volleyball approach jumps. Sagittal plane knee joint kinematics, kinetics, and energetics were quantified in the lead limb, using data obtained from a force platform and an 8-camera motion analysis system. Vertical ground reaction forces and pelvis vertical velocity at takeoff were examined. Independent sample t tests were used to evaluate group differences (α = .05). The tendinopathy group, compared to controls, demonstrated significant reductions (approximately 30%) in net joint work and net joint power during the eccentric phase of the jump, with no differences in the concentric phase. Positive to-negative net joint work and net joint power ratios were significantly higher in the tendinopathy group, which had a net joint work ratio of 1.00 (95% CI: 0.77, 1.24) versus 0.76 (95% CI: 0.64, 0.88) for controls, and a net joint power ratio of 1.62 (95% CI: 1.15, 2.10) versus 1.00 (95% CI: 0.80, 1.21) for controls. There were no significant differences in net joint moment, angular velocity, or range of motion. Peak vertical ground reaction forces were lower for the tendinopathy group, while average vertical ground reaction forces and pelvis vertical velocity were similar. Patellar tendinopathy is associated with differences in sagittal plane mechanical energy absorption at the knee during maximum-effort volleyball approach jumps. Net joint work and net joint power may help define underlying mechanisms, adaptive effects, or rehabilitative strategies for individuals with patellar tendinopathy.

Stochastic Ratcheting on a Funneled Energy Landscape Is Necessary for Highly Efficient Contractility of Actomyosin Force Dipoles

NASA Astrophysics Data System (ADS)

Komianos, James E.; Papoian, Garegin A.

2018-04-01

Current understanding of how contractility emerges in disordered actomyosin networks of nonmuscle cells is still largely based on the intuition derived from earlier works on muscle contractility. In addition, in disordered networks, passive cross-linkers have been hypothesized to percolate force chains in the network, hence, establishing large-scale connectivity between local contractile clusters. This view, however, largely overlooks the free energy of cross-linker binding at the microscale, which, even in the absence of active fluctuations, provides a thermodynamic drive towards highly overlapping filamentous states. In this work, we use stochastic simulations and mean-field theory to shed light on the dynamics of a single actomyosin force dipole—a pair of antiparallel actin filaments interacting with active myosin II motors and passive cross-linkers. We first show that while passive cross-linking without motor activity can produce significant contraction between a pair of actin filaments, driven by thermodynamic favorability of cross-linker binding, a sharp onset of kinetic arrest exists at large cross-link binding energies, greatly diminishing the effectiveness of this contractility mechanism. Then, when considering an active force dipole containing nonmuscle myosin II, we find that cross-linkers can also serve as a structural ratchet when the motor dissociates stochastically from the actin filaments, resulting in significant force amplification when both molecules are present. Our results provide predictions of how actomyosin force dipoles behave at the molecular level with respect to filament boundary conditions, passive cross-linking, and motor activity, which can explicitly be tested using an optical trapping experiment.