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This paper illustrates three examples of how to implement dynamic lifting support, including the solution adopted in the Up n’ Free® (Easy-Walking Inc., Maple Glen, PA). The Up n' Free system can lift the user from a seated posture to a standing position through the employment of a four-bar mechanism and gas piston. When the user is standing, the mechanism can provide partial compensation from gravity to help the user regain mobility. The compensation can be provided while standing without taxing the arms and shoulders with the use of crutches. By using this system, users can sit and stand without assistance from another person and can also receive compensation for gravity loads while walking. This group is not involved with the design and commercialization of the Up n' Free product but uses that design as a reference of comparison for two additional actuation solutions, one of which involves a cam acting on a rubber band. The piston in the Up n' Free is positioned between the bottom part of the walker frame and the four-bar mechanism. We propose a more compact configuration where the piston is located within the four-bar mechanism. This work discusses the pros and cons of the two gas spring cylinder configurations. Common problems arising with both configurations are the difficulty of regulating the minimum and maximum force at the seat, as well as the inability to define a force profile for the transition from sitting to standing. Thus, a new actuation system to implement the dynamic lifting support is proposed, where the force profile is modulated using a cam acting on an elastic band. We were able to define a linear profile of the force during the transition from sit-to-stand, thereby avoiding sudden increases in force that are typical of actuation solutions encompassing gas pistons acting on a variable moment arm.

Paid home care can significantly improve the lives of older adults with disabilities and their families, but recipients often incur substantial out-of-pocket spending. We simulated the financial burden of paid home care for a nationally representative sample of non-Medicaid community-dwelling adults ages sixty-five and older. We found that 74 percent could fund at least two years of a moderate amount of paid home care if they liquidated all of their assets, and 58 percent could fund at least two years of an extensive amount of paid home care. Among older adults with significant disabilities, however, only 57 percent could fund at least two years of moderate paid home care by liquidating all of their assets, and 40 percent could fund at least two years of extensive paid home care. Paid home care could become less affordable if growing labor shortages raise future costs.

A prismatic gas-cooled very high temperature reactor (VHTR) is being developed under the next generation nuclear program. One of the concerns for the reactor design is the effects of a loss of flow accident (LOFA) where the coolant circulators are lost for some reason, causing a loss of forced coolant flow through the core. In the previous studies, the natural circulation in the whole reactor vessel (RV) was obtained by segmentation strategies if the computational fluid dynamic (CFD) analysis with a sufficiently refined mesh was conducted, due to the limits of computer capability. The computational domains in the previous studies were segmented sections which were small flow region models, such as 1/12 sectors, or a combination of a few number of the 1/12 sector (ranging from 2 to 15) using geometric symmetry, for a full dome region. The present paper investigates the flow and heat transfer for a much larger flow region model, a 1/12 core model, using high performance computing. The computation meshes for 1/12 sector and 1/12 reactor core are of 7.8 M and ∼531 M, respectively. Over 85,000 and 35,000 iterations for steady and transient (100 s) calculations are required to achieve convergence, respectively. ∼0.1 min CPU time was required using 192 computer cores for the 1/12 sector model and ∼1.3 min CPU time using 768 cores in parallel for the 1/12 core model, for every iteration, using ALPS, Advanced Large-scale Parallel Superclusters. For the LOFA transient condition, this study employs both laminar flow and different turbulence models to characterize the phenomenon of natural convection. The result of Realizable k–ɛ turbulence model (RKE) model is the most conservative one in the heated blocks (channels) regions, but the result of laminar flow is the most conservative one in the plenum regions. The comparisons of the results from large and small models suggest that large flow model is needed to obtain accurate prediction.

People face a wide range of risks throughout their lifetime that can disrupt employment, reduce earnings, derail retirement planning, and impair economic well-being later in life. This paper measures the impact of health, employment, and marital status shocks on lifetime earnings. Using household survey data from the Survey of Income and Program Participation matched to administrative earnings records, we compared lifetime earnings for people who developed a health problem that limited the type or amount of work they could do, were laid off from their job, or became widowed, divorced, or separated with those who did not experience these shocks. The paper found that: -Employment shocks are fairly common, and disability shocks become much more common as people age. About one in five workers is laid off from their job over a four-year period, even when the job market is robust. About one in seven men and one in six women develop a work-limiting disability in their early 50s. -People who eventually develop disabilities or lose their jobs generally have lower lifetime earnings even before these shocks occur than people who do not experience these shocks. -Health and employment shocks have substantial and long-lasting impacts on earnings. Relative lifetime earnings rank falls by 5 percentile points a decade and a half after disability onset and by 3 percentile points a decade and a half after job loss. The policy implications of the findings are: -Strong safety nets are essential for people who experience health problems and job losses during their working years. -Increased investment in workforce development programs, including retraining of displaced workers, might raise lifetime earnings for workers who have experienced job layoffs.

This study assessed Latinos’ retirement security, including their financial resources and retirement needs, showing past trends and future prospects. Using data from the American Community Survey, decennial censuses, and Health and Retirement Study, tabulations compared poverty rates, income and wealth, health and disability, relationship status, and household composition for Latinos and non-Latinos ages 65 and older. The Urban Institute’s Dynamic Simulation of Income Model also projected income and wealth for future generations. The results show that older Latinos receive less income, hold less wealth, and are more likely to be impoverished than older non-Latino whites. Financial outcomes are significantly worse for older foreign-born Latinos than for those born in the United States. However, projections indicate that the gaps will narrow somewhat in coming decades. Various policy options, such as workforce development initiatives, efforts to promote education and retirement savings, and Social Security reforms that increase benefit progressivity could improve financial security for future Hispanic retirees.

We use two historical data sources – the Health and Retirement Study and the Medicare Current Beneficiary Study – to consider the patterns in older Americans’ severe disability and their use of long-term services and supports (LTSS) by age and socioeconomic status. We then use a dynamic microsimulation model to project how the effects of various interventions to support those with severe disabilities and their caregivers would be distributed across the income distribution. The interventions that we examine fall into three broad classes: tax credits for caregiving expenses, respite care for people in the community with family caregivers, and new social insurance programs. Within each broad class of policies, we examine how sensitive outcomes are to changes in policy details (such as, in the case of tax credits, deductible levels, refundability, and income phase-outs). This paper found that: • Older adults with less education and less wealth are more likely to report disabilities and service use than their more educated and wealthier counterparts. • This pattern persists when we look at people at a point in time but also, more robustly, when we look at their disabilities prospectively. In a sample of older adults who do not report disabilities at baseline, we find that those with fewer economic resources earlier in life are generally more likely to develop disabilities and use paid LTSS over the next two decades, but the differences narrow when we restrict the sample to people who do not develop disabilities until their late 70s. The policy implications of this paper are: • The uneven distribution of disability risks across the population poses challenges for developing effective LTSS policies. Those most likely to need LTSS often lack enough resources to contribute to LTSS programs, and programs that try to contain costs by using underwriting or imposing work requirements often disqualify those who most need coverage. • Certain classes of policies, such as respite care benefits, tend to direct much of their benefits to those in lower income quintiles, according to our projections. Caregiver tax credits and social insurance programs generally distribute benefits more proportionally, although impacts vary depending on how the policies are specified. • Policy design details can significantly affect distributional outcomes. Provisions’ effects can be sensitive to the stacking order in which they are implemented. • It can be useful to examine trends and proposals not only cross-sectionally but also over longer time periods. For example, the distributional effects of social insurance programs depend on the relatively high early-life mortality of those with less education and lower earnings and wealth.

Objective: This study examines differences in retirement decisions between older Hispanics and non-Hispanics, with a special focus on the role of nativity. Methods: We use 1998-2012 waves of the Health and Retirement Study. We estimate survival models of retirement and compare retirement transitions for U.S.-born Hispanics, foreign-born Hispanics, non-Hispanic Whites, and non-Hispanic Blacks. Results: Foreign-born Hispanics retire significantly later than other racial and ethnic groups. Controlling for personal characteristics, their risk of retirement is 39% lower compared with non-Hispanic Whites. Retirement transitions do not differ significantly between U.S.-born Hispanics and non-Hispanic Whites. Discussion: Difference in retirement timing between U.S.- and foreign-born Hispanics may partly be due to lower incomes and wealth accumulation of foreign-born Hispanics. Workforce development initiatives, policy initiatives promoting retirement savings, and Social Security reforms could improve future retirement security for older Hispanics, and make retirement a viable option for more foreign-born Hispanics.

Atomic layer deposition (ALD) is a vapor phase technique capable of producing thin films of a variety of materials. Based on sequential, self-limiting reactions, ALD offers exceptional conformality on high-aspect ratio structures, thickness control at the Angstrom level, and tunable film composition. With these advantages, ALD has emerged as a powerful tool for many industrial and research applications. In this review, we provide a brief introduction to ALD and highlight select applications, including Cu(In,Ga)Se2 solar cell devices, high-k transistors, and solid oxide fuel cells. These examples are chosen to illustrate the variety of technologies that are impacted by ALD, the range of materials that ALD can deposit – from metal oxides such as Zn1−xSnxOy, ZrO2, Y2O3, to noble metals such as Pt – and the way in which the unique features of ALD can enable new levels of performance and deeper fundamental understanding to be achieved.

Bypass flow in the prismatic gas-cooled very high temperature reactor (VHTR) is not intentionally designed to occur, but is present in the gaps between graphite blocks. Previous studies of the bypass flow in the core indicated that the cooling provided by flow in the bypass gaps had a significant effect on temperature and flow distributions for normal operating conditions. However, the flow and heat transports in the core are changed significantly after a Loss of Flow Accident (LOFA). This study aims to study the effect and role of the bypass flow after a LOFA in terms of the temperature and flow distributions and for the heat transport out of the core by natural convection of the coolant for a 1/12 symmetric section of the active core which is composed of images and mirror images of two sub-region models. The two sub-region models, 9 × 1/12 and 15 × 1/12 symmetric sectors of the active core, are employed as the CFD flow models using computational grid systems of 70.2 million and 117 million nodes, respectively. It is concluded that the effect of bypass flow is significant for the initial conditions and the beginning of LOFA, but the bypass flow has little effect after a long period of time in the transient computation of natural circulation.

Various policy developments and long-term economic, social, and demographic trends raise worrisome questions about the financial security of future retirees. An erosion in employer-sponsored defined benefit pension coverage and the increase in Social Security’s full retirement age could shrink future benefits. Stagnating employment and earnings for men could threaten future retirement security, because retirement benefits and the capacity to save depend on lifetime earnings. The financial crisis, Great Recession, and collapse of the housing market in the second half of the previous decade could significantly disrupt retirement savings. This paper assesses retirement prospects for future generations, with a special focus on the late Generation-X and Millennial generations. Because retirement outcomes depend on how much people earned and saved when they were younger, the analysis compares trends in employment, earnings, pension coverage, and wealth during working ages across cohorts, using data from the Current Population Survey and the Survey of Consumer Finances. The analysis also projects age-70 incomes for future generations using DYNASIM4, the Urban Institute’s dynamic microsimulation model. This paper found that: - Many recent trends threaten future retirement security, including continuing declines in men’s employment before age 55, stagnating median earnings for men, and a sharp decline in median household wealth after 2007. - Other trends are more encouraging. Gen-X and Millennial women worked and earned more in their 20s and 30s than now-retired women did at those ages, and Millennial men and women are much more likely to have a four-year college degree than previous cohorts. - Projections show that median age-70 income will be higher for Gen-Xers and Millennials than previous generations as earnings grow over time. - However, a larger share of retired Gen-Xers and Millennials will be unable to replace at least three-quarters of their pre-retirement earnings, according to the projections, and will see their living standards decline when they retire. The policy implications of this paper are: - How employment, earnings, and savings patterns evolve over the next three decades will shape Millennials’ retirement incomes. - Policy choices regarding retirement programs, especially strategies to address Social Security’s long-term financing gap, will significantly affect the retirement security of future generations.

To better understand the contribution of private lands enrolled in conservation easement programs to wintering waterfowl habitat and energetics, we evaluated effects of management strategies on seed biomass, species richness, and presence of beneficial (i.e., considered to have nutritional value to waterfowl) and introduced species on 32 Wetland Reserve Program easements in Arkansas and Mississippi. We collected soil core samples from seasonal wetlands with active and passive management strategies in 2008–2009. Overall mean (±SE) biomass for all seeds was 527.8 (±28.5) kg/ha, whereas mean biomass of beneficial seeds was 263.5 (±18.5) kg/ha. Actively managed sites in Mississippi had greater beneficial seed mass compared to passively managed sites, whereas management had no effect on beneficial seed mass in Arkansas in fall 2008 and in fall 2009, passive sites had greater beneficial seed mass than active sites. Our estimate of beneficial seed biomass on WRP easements represents a 47 % reduction in estimated food availability for waterfowl on privately owned wetlands. Lower estimates of food availability on privately owned, seasonal wetlands in the lower Mississippi Alluvial Valley may warrant increased conservation efforts for seasonal wetlands or additional emphasis on management techniques to increase moist-soil seed biomass on privately owned seasonal wetlands.

Available computational fluid dynamics (CFD) predictions of pressure distributions in the vertical bypass flow between blocks in a prismatic gas-cooled reactor (GCR) have been analyzed to deduce apparent friction factors and loss coefficients for nuclear engineering systems and network codes. Calculations were performed for vertical gap spacings “s” of 2, 6, and 10 mm — representing 1, 3, and 5 mm in a GCR design, horizontal gaps between the blocks of 2 mm and two flow rates, giving a range of vertical gap Reynolds numbers ReDh of about 40–5300. The present focus is on the examination of the flow in the vertical gaps. Horizontal gaps are treated in CFD calculations but their flows are not examined. Laminar predictions of the fully developed friction factor ffd were about 3–10% lower than the classical infinitely wide channel. In the entry region, the local apparent friction factor was slightly higher than the classic idealized case, but the hydraulic entry length Lhy was approximately the same. The per cent reduction in flow resistance was greater than the per cent increase in flow area at the vertical corners of the blocks. The standard k–ϵ turbulence model was employed for flows expected to be turbulent. Its predictions of ffd and flow resistance were significantly higher than direct numerical simulations (DNS) for the classic case; the value of Lhy was about 30 gap spacings. Initial quantitative information for entry coefficients and loss coefficients for the expansion–contraction junctions between blocks is also presented. The present study demonstrates how CFD predictions can be employed to provide integral quantities needed in systems and network codes.

We analyzed a new class of passive devices that can help individuals regain their independence. A new walker design has been commercialized under the name of UP’N FREE®1. This new design can lift the user from a seated posture to a standing position through the employment of a four bar mechanism and gas piston. When the user is standing, the mechanism can provide partial compensation from gravity to help the user regain mobility. By using this system, users can sit and stand without another person’s assistance and can also compensate for gravity loads during walking both indoor and outdoor. This paper illustrates two examples of how to implement the dynamic lifting support and discusses the pros and cons of different system configuratons of a a gas spring cylinder as a passive actuator.

Significant uncertainty exists about the effects of bypass flow in a prismatic gas-cooled very high temperature reactor (VHTR). Bypass flow is the flow in the gaps between prismatic graphite blocks in the core. The gaps are present because of variations in their construction, imperfect installation and expansion and shrinkage from thermal heating and neutron fluence. Calculations are performed using computational fluid dynamics (CFD) for flow of the helium coolant in the gap and coolant channels along with conjugate heat generation and heat transfer in the fuel compacts and graphite. A commercial CFD code is used for all of the computations. A one-twelfth sector of a standard hexagonal block column is used for the CFD model because of its symmetry. Various scenarios are computed by varying the gap width from zero to 5 mm, varying the total heat generation rate to examine average and peak radial generation rates and variation of the graphite block geometry to account for the effects of shrinkage caused by irradiation. The calculations are for a 350 MWth prismatic reactor. It is shown that the effect of increasing gap width, while maintaining the same total mass flow rate, causes increased maximum fuel temperature while providing significant coolingmore » to the near-gap region. The maximum outlet coolant temperature variation is increased by the presence of gap flow and also by an increase in total heat generation with a gap present. The effect of block shrinkage is actually to decrease maximum fuel temperature compared to a similar reference case.« less

This paper is the second part of a two part sequence on multiphysics algorithms and software. The first [1] focused on the algorithms; this part treats the multiphysics software framework and applications based on it. Tight coupling is typically designed into the analysis application at inception, as such an application is strongly tied to a composite nonlinear solver that arrives at the final solution by treating all equations simultaneously. The application must also take care to minimize both time and space error between the physics, particularly if more than one mesh representation is needed in the solution process. This paper presents an application framework that was specifically designed to support tightly coupled multiphysics analysis. The Multiphysics Object Oriented Simulation Environment (MOOSE) is based on the Jacobian-free Newton-Krylov (JFNK) method combined with physics-based preconditioning to provide the underlying mathematical structure for applications. The report concludes with the presentation of a host of nuclear, energy and environmental applications that demonstrate the efficacy of the approach and the utility of a well-designed multiphysics framework.

Phased retirement programs that allow older workers to reduce their hours and responsibilities and pursue more flexible work schedules could satisfy both the employee’s desire for flexibility and the employer’s need to maintain an experienced workforce. However, few employers have established formal programs, because they often complicate the provision of other benefits and might violate antidiscrimination rules. For example, federal laws limit retirement plan distributions to employees who are still working for the plan sponsor, which discourages phased retirement because few older workers can afford to reduce their work hours unless they can receive at least some retirement benefits. Many employers do not provide fringe benefits to part-time employees, and making exceptions for older workers could violate antidiscrimination rules. Federal laws requiring that benefits provided through tax-qualified plans be evenly distributed between highly compensated and lower-paid employees also complicate formal phased retirement programs. Reforming these policies could promote phased retirement.

The core bypass flow in a prismatic very high temperature reactor (VHTR) is an important design consideration and can have considerable impact on the condition of reactor core internals including fuels. The interstitial gaps are an inherent presence in the reactor core because of tolerances in manufacturing the blocks and the inexact nature of their installation. Furthermore, the geometry of the graphite blocks changes over the lifetime of the reactor because of thermal expansion and irradiation damage. The occurrence of hot spots in the core and lower plenum and hot streaking in the lower plenum (regions of very hot gas flow) are affected by bypass flow. In the present study, three-dimensional computational fluid dynamic (CFD) calculations of a typical prismatic VHTR are conducted to better understand bypass flow phenomena and establish an evaluation method for the reactor core using the commercial CFD code FLUENT. Parametric calculations changing several factors in a one-twelfth sector of a fuel column are performed. The simulations show the impact of each factor on bypass flow and the resulting flow and temperature distributions in the prismatic core. Factors include inter-column gap-width, turbulence model, axial heat generation profile and geometry change from irradiation-induced shrinkage in the graphite block region. It is shown that bypass flow provides a significant cooling effect on the prismatic block and that the maximum fuel and coolant channel outlet temperatures increase with an increase in gap-width, especially when a peak radial factor is applied to the total heat generation rate. Also, the presence of bypass flow causes a large lateral temperature gradient in the block and also dramatically increases the variation in coolant channel outlet temperatures for a given block that may have repercussions on the structural integrity of the graphite, the neutronics and the potential for hot streaking and hot spots occurring in the lower plenum.

Objectives. The impending retirement of boomers has spurred interest in tapping their productive energies to benefi t society. This study examined volunteer transitions among older adults to understand the factors that affect volunteer dynamics. Methods. Using data from the Health and Retirement Study, the analysis examined entries into and exits from formal volunteer activities between 1996 and 2004 by adults aged 55 – 65 at study baseline. The study showed the duration of volunteer activities, the probability that older adults start and stop volunteering, and the factors that signifi cantly predict volunteer transitions. Results. The fi ndings reveal considerable stability among both volunteers and nonvolunteers; however, older adults are more likely to stop volunteering than to start. Volunteers who contribute intensely and for many years and who are married to volunteers are the least likely to quit. And nonvolunteers are more likely to start volunteering if they have been uninvolved for few years and their spouses volunteer. Conclusions. The results point to the need to focus efforts on retaining older volunteers to maximize volunteer engagement during later years. Recruiting older adults in volunteer activities early on, ideally before they retire, could also help meet volunteer needs.

Caring for the elderly imposes financial burdens and strains families. System changes are necessary to mitigate these problems. Virtual Mentor is a monthly bioethics journal published by the American Medical Association.

Validation simulations are presented for turbulent flow in a staggered tube bank, geometry similar to the lower plenum of a gas-cooled high temperature reactor. Steady 2D RANS results are compared to unsteady 2D RANS results and experiment. The unsteady calculations account for the fact that nonturbulent fluctuations (due to vortex-shedding) are present in the flow. The unsteady computations are shown to predict the mean variables and the total shear stress quite well. Previous workers’ results indicate that 3D simulations are needed to obtain reasonable agreement; present results indicate 2D is sufficient. Best practices are based on requirements for the ASME Journal of Fluids Engineering.

We radio-tracked nine Masticophis flagellum (Coachwhips) to determine home range, habitat use, and movements in eastern Texas from April to October 2000. Home ranges of Coachwhips contained more oak savanna macrohabitat than early-successional pine plantation or forested seep, based on the availability of these three macrohabitats in the study area. Likewise, within their individual home ranges, Coachwhips used oak savanna more than the other two macrohabitats, based on availability. An analysis of microhabitat use revealed that, relative to random sites within their home range, Coachwhips were found at sites with fewer pine trees and more herbaceous vegetation taller than 30 cm. Results of the two analyses, macrohabitat and microhabitat, were consistent: oak savannas contained relatively few pine trees but much herbaceous vegetation taller than 30 cm. Coachwhips made frequent long-distance moves, which resulted in large home ranges. Core activity areas, however, were small. These core activity areas were always within the oak savanna macrohabitat. Long movements, large home ranges, and small core activity areas likely were a result of the preferred oak savanna macrohabitat being patchily distributed in the landscape.

About half of older Americans will need a high level of assistance with routine activities for a prolonged period of time. This help is commonly referred to as long-term services and supports (LTSS). Under current policies, these individuals will fund roughly half of their paid care out of pocket. Partly as a result of high costs and uncertainty, relatively few people purchase private long-term care insurance or save sufficiently to fully finance LTSS; many will eventually turn to Medicaid for help. To show how policy changes could expand insurance's role in financing these needs, we modeled several new insurance options. Specifically, we looked at a front-end-only benefit that provides coverage relatively early in the period of disability but caps benefits, a back-end benefit with no lifetime limit, and a combined comprehensive benefit. We modeled mandatory and voluntary versions of each option, and subsidized and unsubsidized versions of each voluntary option. We identified important differences among the alternatives, highlighting relevant trade-offs that policy makers can consider in evaluating proposals. If the primary goal is to significantly increase insurance coverage, the mandatory options would be more successful than the voluntary versions. If the major aim is to reduce Medicaid costs, the comprehensive and back-end mandatory options would be most beneficial.

Although millions of older Americans rely on employer-sponsored retiree health benefits to help pay their medical expenses, declines in this coverage have been documented. Using data from the Medical Expenditure Panel Survey, our findings reveal steady erosion in retiree health benefits since the mid-1990s. Based on this much larger survey of private establishments than previous studies have used, we conclude that in 2003 only about one-quarter of private-sector employees worked at establishments that offered health benefits to retirees, down from 32 percent in 1997. Private firms have also been passing higher shares of health insurance costs to retirees.

Encouraging work at older ages is a crucial policy goal for an aging society, but many features of the benefits and tax system discourage work. This study computes the implicit tax rate on work at older ages, broadly defined to include standard income and payroll taxes as well as changes in future Social Security benefits, employer–provided pension benefits, and health benefits associated with an additional year of employment. The results show that the implicit tax rate on work increases rapidly with age, rising from 14 percent at age 55 for a typical man to nearly 50 percent at age 70.

Collocation methods are investigated because of their simplicity and inherent efficiency for application to a model problem with similarities to the equations of fluid dynamics. The model problem is a steady, one-dimensional convection-diffusion equation with constant coefficients. The objective of the present research is to compare the efficiency and accuracy of several collocation schemes as applied to the model problem for values of 15 and 50 for the associated Peclet number. The application of standard nodal and orthogonal collocation is compared to the use of the Greville abscissae for the collocation points, in conjunction with cubic and quartic B-splines. The continuity of the B-spline curve solution is varied from C1 continuity for traditional orthogonal collocation of cubic and quartic splines to C2-C3 continuity for cubic and quartic splines employing nodal, orthogonal and Greville point collocation. The application of nodal, one-point orthogonal, and Greville collocation for smoothest quartic B-splines is found to be as accurate as for traditional two-point orthogonal collocation using cubics, while having comparable or better efficiency based on operation count. Greville collocation is more convenient than nodal or 1-point orthogonal collocation because exactly the correct number of collocation points is available.

Employers are beginning to search for ways to elicit more labor supply from older adults as the population ages, the ability to work in later life increases, and younger workers become relatively scarce. Many employers are turning to hybrid pension plans, such as cash balance plans and pension equity plans. Whereas traditional defined benefit plans often subsidize workers who retire early and penalize those who remain at work beyond the plan's retirement age, most hybrid plans reward work at older ages. This paper documents the impact of population aging on the labor market and changes over time in work capacity at older ages. It then shows how movement toward hybrid pension plans, among other types of private and public retirement plan reforms and redesigns, can be used to increase work incentives for older adults.

Objectives. Many single mothers are likely to face special economic challenges in old age, because they often have limited employment histories and cannot rely on husbands for financial support. This article examines the economic status of these women in later life. Methods. The analysis uses nationally representative data from the Health and Retirement Study to estimate multivariate models of income, assets. and poverty rates for women aged 65-75 in 1999. Results. Controlling for education, current marital status, and race and ethnicity, the models indicate that women who spent ≥ 10 years raising dependent children outside of marriage are 55% more likely to live in poverty at ages 65-75 than women who were always married when their children were young. Discussion. The financial difficulties confronting single mothers raising children persist into later life. Social Security reforms, especially those that are not tied to the current system of spousal and survivor benefits, could improve retirement security for these vulnerable women, whose numbers will begin to soar when the many women who raised children outside of marriage in the 1970s retire in coming years.

The conversion of traditional defined benefit plans to cash balance plans is among the most controversial aspects of pension policy today. Because the controversy has focused on the treatment of older workers, however, the debate has generally ignored the long–term implications for retirement security. This article examines the potential impact of cash balance plans on workers who spend their entire careers in these plans, and focuses on the implications for mobile workers and for labor supply at older ages. The evidence suggests that cash balance plans can often provide more retirement security than traditional defined benefit plans or defined contribution plans.

This paper investigates the use of the control points of the Bernstein-Bezier form for numerically solving differential equations. Two least squares type schemes based on degree raising and subdivision are proposed. The convergence of the methods applied to two-point boundary value problems is analyzed.

This paper describes contributions to employer–sponsored retirement accounts, using newly available longitudinal data that combine administrative earnings records with survey data. The results reveal a fair amount of individual variability in contribution rates over time. However, potential negative shocks to income and increases in current consumption needs do not appear to lead workers to curtail their contributions. Instead, workers appear to raise their contribution rates after they have achieved key milestones in the lifecourse, such as the birth of a child or the purchase of a home.

Recent pension plan conversions by numerous large employers have sparked debate about the merits of cash balance plans. This article compares pension wealth in traditional defined benefit (DB) plans and cash balance plans for a national sample of covered Americans aged 51 to 61. The simulations indicate that replacing DB plans with cash balance plans would redistribute pension wealth from those with long-term jobs to those with multiple short-term jobs and from those with substantial pension benefits to those with more limited benefits. Perhaps unexpectedly, women at midlife in 1992 with DB coverage would lose wealth in cash balance plans, but future cohorts of women are likely to fare better.

The loss of health insurance may be an important component of the cost of retirement, especially for workers without retiree health insurance coverage. The authors find that insurance costs significantly reduce retirement rates for full-time wage and salary workers ages 51 to 61. Simulations suggest that a $1,000 increase in the net present value of health insurance premium costs reduces the probability of early retirement by 0.17 percentage points for men and by 0.24 percentage points for women, corresponding to elasticities of -0.22 and -0.24, respectively. The authors' models predict that expanding the Medicare program to cover those aged 62-64 would increase retirement rates for workers with employer-sponsored coverage who lack retiree benefits, if the government subsidizes their coverage. However, the impact would be small, increasing overall retirement rates by only 7%. (Author's abstract.) (Free full-text download available at http://digitalcommons.ilr.cornell.edu/ilrreview/.)

The most efficient architecture for achieving high donor/acceptor interfacial area in organic photovoltaics (OPVs) would employ arrays of vertically interdigitated p- and n- type semiconductor nanopillars (NPs). Such morphology could have an advantage in bulk heterojunction systems; however, precise control of the dimension morphology in a crystalline, interpenetrating architecture has not yet been realized. Here we present a simple, yet facile, crystallization technique for the growth of vertically oriented NPs utilizing a modified thermal evaporation technique that hinges on a fast deposition rate, short substrate-source distance, and ballistic mass transport. A broad range of organic semiconductor materials is beneficial from the technique to generate NP geometries. Moreover, this technique can also be generalized to various substrates, namely, graphene, PEDOT-PSS, ZnO, CuI, MoO3, and MoS2. The advantage of the NP architecture over the conventional thin film counterpart is demonstrated with an increase of power conversion efficiency of 32% in photovoltaics. This technique will advance the knowledge of organic semiconductor crystallization and create opportunities for the fabrication and processing of NPs for applications that include solar cells, charge storage devices, sensors, and vertical transistors.