A framework for optimizing hydrologic performance of green roof media.

One of the primary functions of green roofs in urban areas is to moderate rainwater runoff, and one of the major impediments to the survival of plants on an extensive green roof (EGR) is a lack of available water during dry periods. Runoff moderation and water storage are both influenced by the composition of the growing media. Here we present a framework for evaluating the hydrologic performance of EGR growing media and also provide hydrologic attribute data for several commonly used EGR media constituents.

The effects of long-term management on patterns of carbon storage in a northern highbush blueberry production system.

Perennial crops potentially provide a sink for atmospheric carbon. However, there is a poor understanding of how perennial crops differ in their carbon allocation patterns, and few studies have tested how agronomic practices such as fertilization influence long-term patterns of carbon allocation in actual production systems. In this study, we report results of a long-term field experiment that tested the individual and combined effects of organic matter incorporation and nitrogen fertilization on carbon allocation.

Plant species' origin predicts dominance and response to nutrient enrichment and herbivores in global grasslands.

Exotic species dominate many communities; however the functional significance of species' biogeographic origin remains highly contentious. This debate is fuelled in part by the lack of globally replicated, systematic data assessing the relationship between species provenance, function and response to perturbations. We examined the abundance of native and exotic plant species at 64 grasslands in 13 countries, and at a subset of the sites we experimentally tested native and exotic species responses to two fundamental drivers of invasion, mineral nutrient supplies and vertebrate herbivory.

Multicultural voices: Attitudes of older adults in the United States about elder mistreatment.

Despite international growth in policies to increase the identification and response to elder abuse and neglect, there remain considerable barriers to treating the problem. Some of these barriers may be attributed to how older adults from different racial/ethnic backgrounds define, experience, and seek to remedy elder mistreatment. Using focus group discussions based on case vignettes, this paper examines how older adults from different racial and ethnic backgrounds in the United States perceive elder mistreatment.

Predicting invasion in grassland ecosystems: is exotic dominance the real embarrassment of richness?

Invasions have increased the size of regional species pools, but are typically assumed to reduce native diversity. However, global-scale tests of this assumption have been elusive because of the focus on exotic species richness, rather than relative abundance. This is problematic because low invader richness can indicate invasion resistance by the native community or, alternatively, dominance by a single exotic species.

Productivity is a poor predictor of plant species richness.

For more than 30 years, the relationship between net primary productivity and species richness has generated intense debate in ecology about the processes regulating local diversity. The original view, which is still widely accepted, holds that the relationship is hump-shaped, with richness first rising and then declining with increasing productivity. Although recent meta-analyses questioned the generality of hump-shaped patterns, these syntheses have been criticized for failing to account for methodological differences among studies.

Evaluating a multicomponent caregiver intervention.

There is compelling evidence that caring for an elderly individual with functional limitations is physically and psychologically stressful. The purpose of this study is to test a multimodal caregiver intervention of ethnically and racially diverse caregivers. We sought to examine if caregivers (n=199) of older adults with physical and/or cognitive problems experienced improved depression and caregiver outcomes after participating in a community-based Caregiver Support/Training Program (CS/TP).

Nitrogen inputs promote the spread of an invasive marsh grass.

Excess nutrient loading and large-scale invasion by nonnatives are two of the most pervasive and damaging threats to the biotic and economic integrity of our estuaries. Individually, these are potent forces, but it is important to consider their interactive impacts as well. In this study we investigated the potential limitation of a nonnative intertidal grass, Spartina alterniflora, by nitrogen (N) in estuaries of the western United States.

Ecosystem engineering in space and time.

The ecosystem engineering concept focuses on how organisms physically change the abiotic environment and how this feeds back to the biota. While the concept was formally introduced a little more than 10 years ago, the underpinning of the concept can be traced back to more than a century to the early work of Darwin. The formal application of the idea is yielding new insights into the role of species in ecosystems and many other areas of basic and applied ecology.

Invasion in a heterogeneous world: resistance, coexistence or hostile takeover?

We review and synthesize recent developments in the study of the invasion of communities in heterogeneous environments, considering both the invasibility of the community and impacts to the community. We consider both empirical and theoretical studies. For each of three major kinds of environmental heterogeneity (temporal, spatial and invader-driven), we find evidence that heterogeneity is critical to the invasibility of the community, the rate of spread, and the impacts on the community following invasion.

Using ecosystem engineers to restore ecological systems.

Ecosystem engineers affect other organisms by creating, modifying, maintaining or destroying habitats. Despite widespread recognition of these often important effects, the ecosystem engineering concept has yet to be widely used in ecological applications. Here, we present a conceptual framework that shows how consideration of ecosystem engineers can be used to assess the likelihood of restoration of a system to a desired state, the type of changes necessary for successful restoration and how restoration efforts can be most effectively partitioned between direct human intervention and natural ecosystem engineers.

Spatially variable propagule pressure and herbivory influence invasion of chaparral shrubland by an exotic grass.

Although numerous studies have identified mechanisms that either resist or facilitate biological invasions, few studies have explicitly tested how resisting and facilitating mechanisms interact to drive invasion success. In California, USA, undisturbed Mediterranean-type shrublands have resisted invasion by the perennial tussock grass Cortaderia jubata. In some cases, however, this resistance has been spectacularly breached even in the absence of large-scale disturbance.

Pollen limitation causes an Allee effect in a wind-pollinated invasive grass (Spartina alterniflora).

It is usually assumed that pollen availability does not limit reproduction in wind-pollinated plants. Little evidence either supporting or contradicting this assumption exists, despite the importance of seed production to population persistence and growth. We investigated the role of pollen limitation in an invasive estuarine grass (Spartina alterniflora), with a manipulative pollen supplementation and exclusion experiment in areas of high population density and at the low-density leading edge of the invasion.

Increasing nursing hours without increasing nurses: a natural experiment at an academic medical center.

The compensation plans at many hospitals do not encourage nurses to provide the maximum number or hours at the lowest possible costs. The authors discuss a compensation method that increased nursing hours while decreasing nursing costs. This effort was achieved with the support of the overwhelming majority of the nursing staff.

Does managed care more efficiently allocate resources to older patients in critical care settings?

Objective: To evaluate resource utilization by elderly patients with respiratory failure in order to compare the efficiency of managed care and non-managed care payers.

Design: Regression analysis is applied to predict survival rate and the payments per life saved as a function of managed care participation, sociodemographics, and clinical risk factors.

Setting: Acute care hospitals in New York State.

A cost-benefit analysis of mechanical ventilation. An examination of DRG 475.

Objective: An economic evaluation of the resources used for mechanically ventilated patients using various measures for the benefits of extending life.

Methods: Regression analysis is applied to New York State discharge data for patients under DRG 475 during 1992-96 to predict age-specific survival rates and payments per life saved. Sensitivity analysis is used to compare benefits of extending life associated with different economic values of life with the payments per life saved at each age.

Patterns in costs and outcomes for patients with prolonged mechanical ventilation undergoing tracheostomy: an analysis of discharges under diagnosis-related group 483 in New York State from 1992 to 1996.

Objective: To analyze the costs and discharge status for patients with prolonged mechanical ventilation undergoing tracheostomy.

Design: Retrospective analysis of a statewide database.

Patients: All patients (n = 37,573) >18 yrs of age who had prolonged mechanical ventilation (procedure code 96.

Clinical and economic outcome of mechanically ventilated patients in New York State during 1993: analysis of 10,473 cases under DRG 475.

Study Objectives: To examine and describe the relationship between age and disposition in patients undergoing mechanical ventilation.

Design: Retrospective analysis of a statewide database.

Setting: All acute-care hospitals in New York State.

Clinical and economic outcome of patients undergoing tracheostomy for prolonged mechanical ventilation in New York state during 1993: analysis of 6,353 cases under diagnosis-related group 483.

Objective: To examine and describe the relation between age and disposition in patients undergoing tracheostomy.

Design: Retrospective analysis of a statewide database.

Setting: All acute care hospitals in New York state.

Investigating the impact of age on outcome of mechanical ventilation using a population of 41,848 patients from a statewide database.

Study Objective: To examine the impact of age on outcome from mechanical ventilation.

Design: Retrospective analysis of a statewide database.

Setting: All acute-care hospitals in New York State.

The intensive care unit medical director as manager. Impact on performance.

This article examines the impact of greater management involvement by the medical director on efficiency of bed allocation in the intensive care unit (ICU) or critical care unit. Managerial involvement is modeled using a principal components approach in terms of perceived supervision, conflict resolution regarding bed allocation at critical times, extent of control over treatment, and employment status. Using data from a 1991 survey of 2,879 ICUs in 1,706 hospitals conducted by the Society of Critical Care Medicine, two equations reflecting efficiency--the ICU occupancy rate and the presence of misallocated ICU patients--were estimated.

Mechanical ventilation for the elderly patient in intensive care. Incremental changes and benefits.

Objective: To evaluate the cost-effectiveness of prolonged mechanical ventilation in patients 80 years of age and older in the intensive care unit (ICU).

Design: A retrospective review of consecutive ICU patients requiring 3 or more days of mechanical ventilation. Cost-effectiveness analysis was performed by assessing incremental hospital charges from hospital billing records; charges were then related to years of life saved.

Zidovudine's impact on resource use by patients with symptomatic HIV illness: a large sample analysis.

This study used a longitudinal data set of 4,957 patients and 39,455 patient-months of observation, drawn from 17 months of data on patients with symptomatic HIV disease identified from the New York State Medicaid Program. Multivariate regression analysis was used to evaluate the effect of AZT on the use of several medical services. The results show that AZT produced substantial reductions in resource use.

The optimal stock of health with endogenous wages. Application to partial disability compensation.

The optimal quantity of health is examined in the framework of a model which posits that health capital will influence earning capacity in addition to the supply of labor. Utilizing data from the Survey of Disabled and Nondisabled Adults, eight health capital variables are tested in models of hourly wages, labor supply and yearly earnings. The results for three of the health capital variables are then compared to their evaluation by the American Medical Association and by the New York State Workers' Compensation program.