Defining and analyzing health system resilience in rural jurisdictions

Environment Systems and Decisions - Rural areas face well known and distinctive health care challenges that can limit their resilience in the face of health emergencies such as the COVID-19...     

探究式教学模式下物理实验的设计与实现

随着新的教育、教学技术的不断涌现和新的教学模式的提出,传统的实验教学模式已经不能满足现代素质教育的要求,急需新的更为先进的教学模式来提高实验教学的效果。在此背景下,笔者通过研究探究式教学模式,并将此模式应用到大学物理实验教学中,取得了良好的效果。     

Group absenteeism and positive affective tone: a longitudinal study

This study investigates temporal variation in group absence behavior, and the relationship between group absenteeism and the group's positive affective tone. Absenteeism data were obtained from 97 work groups, aggregated over each of the four quarters of a year. The group's positive affective tone was measured through two employee opinion surveys. Multi‐level regression analyses were carried out, in which linear, quadratic, and cubic change trends were tested as predictors of change over time in group absenteeism. All three change trends explained unique variance in the group absenteeism data, indicating that the level of group absenteeism changes over time. We also found that there was significant variation between groups in the strength and direction of the linear and quadratic change trends. Positive affective tone was negatively related to the level of group absenteeism, and change in positive affective tone predicted the strength and direction of the linear change trend for group absenteeism. Copyright © 2003 John Wiley & Sons, Ltd.     

Organochlorine pesticide residues and PCBs in eels ( ) from some British freshwater reedbeds

Organochlorine pesticide residues and PCBs were measured in bulked samples of whole eels collected in 1991 from 11 reedbed sites of wildlife conservation importance in Britain. Eels from some sites had only trace amounts of dieldrin, p,p-DDE and PCBs. Maximum concentrations were 0.21 mg kg⁻¹ for dieldrin, 0.27 mg kg⁻¹ for p,p-DDE and 0.91mg kg⁻¹ for PCBs (fresh weight). Concentrations of contaminants in eels from reedbeds were considered in general to be lower than in eels from rivers, but nevertheless concentrations were considered to be sufficiently high at some sites to adversely affect top carnivores such as the otter.     

The overlooked role of New York City urban yards in mitigating and adapting to climate change

There is a dearth of research focusing on the role that urban residential open space plays in climate change adaptation, despite evidence suggesting that environmental benefits accrue when even small pockets of open space are made permeable and vegetated. In densely built New York City, there are 21,448?ha (53,000 acres) of such land. One city block with adjoining contiguous open space was investigated to quantify its existing environmental value and also its potential to provide enhanced services through redesign. The study block's open space was found to be 35% permeable and planted with 96 trees, storing 45,359?kg (100,000?lb) of carbon. Simulations conducted using the United States Environmental Protection Agency Stormwater Management Model contrasting normal, light, and heavy precipitation years suggested that increases in annual precipitation could be fully mitigated by reducing impervious surface cover by 25%. The preservation of the existing vegetated residential urban open space and the conversion of paved surfaces to a pervious condition both appear to be effective strategies for enhancing the city's ability to adapt to and mitigate for climate change.     

The additionality problem with offsets: Optimal contracts for carbon sequestration in forests

Carbon offsets are a frequently discussed tool for reducing the costs of an emissions reduction policy. However, offsets have a basic problem stemming from asymmetric information. Sellers of offsets have private information about their opportunity costs, leading to concerns about whether offsets are additional. Non-additional offsets can undermine a cap-and-trade program or, if the government purchases them directly, result in enormous government expenditures. We analyze contracts for carbon sequestration in forests that mitigate the asymmetric information problem. Landowners are offered a menu of two-part contracts that induces them to reveal their type. Under this scheme, the government is able to identify ex post how much additional forest each landowner contributes and minimize ex ante its expenditures on carbon sequestration. To explore the performance of the contracting scheme, we conduct a national-scale simulation using an econometric model of land-use change. The results indicate that for an increase in forest area of 61 million acres, government expenditures are $5.3 billion lower under the contracting approach compared to a uniform subsidy offered to all landowners. This compares to an increase in private opportunity costs of just $110 million dollars under the contracts. Thus, the contracting scheme is preferable from society's perspective.     

Book reviews

Frances Sharples is a terrestrial ecologist in the Environmental Science Division of the Oak Ridge National Laboratory in Oak Ridge, Tennessee, operated by Martin Marietta Energy Systems, Inc., under Contract No. DE-AC05-840R21400 with the US Department of Energy. Publication No. 3413, Environmental Sciences Division, ORNL.