Patch use by Dipodomys deserti (Rodentia: Heteromyidae): profitability,preference, and depletion dynamics

Summary Granivorous desert rodents of the family Heteromyidae forage nonrandomly among microhabitats that vary in substrate, seed densities, and seed species composition. To explore the hypothesis that microhabitat use is sensitive to seed patch profitability, we quantified effects of seed size (1.96 vs. 5.21 mg/seed) and density (0.4–10.6 seeds/cm²) on Dipodomys deserti harvest rates, which is a measure of profitability when expressed as mg of seed taken per min. By manipulating seed density, we created large-seed and small-seed patches of known relative profitability and exposed D. deserti individuals to pairwise choices in the laboratory and field. We used three treatment classes: 1) large-seed patches that were more profitable than small-seed patches (equal seed densities); 2) large-seed and small-seed patches that were equally profitable (small-seed densities somewhat higher): and 3) large-seed patches that were less profitable than small-seed patches (small-seed densities much higher). Harvest rate increased nearly linearly with seed density, and profitability of large-seed patches was greater than small-seed patches of the same density. Cumulative harvest from a patch increased linearly with residence time up to a plateau; this gain curve indicates that animals move systematically within patches and hence avoid resampling already depleted areas. In the laboratory, animals visited small-seed patches first more often and visited them more frequently when they were more profitable than large-seed patches. When large-seed patches were of greater or equal profitability, large-seed patches were preferred by both measures. The expressed preference for large-seed patches, when animals were presented with equally profitable patches, suggests an underlying preference for large seeds. In the field, animals depleted all patches to a constant low profitability, in accord with qualitative predictions of optimal patch use models. These results suggest that patch preferences by D. deserti are affected by the economics of seed harvest.     

Integrated analysis of metallic resource flows

In January 1997, the German Research Association (DFG) established a special research programme for an integrated analysis of metallic resource flows. The programme is a joint interdisciplinary effort of the Technical University of Aachen and of the Research Centre Jiilich. Apart from many other activities, a series of conferences is organised within this programme. In October 1997, a first conference was held on “The Economics of Resource Flows: The Case of Aluminium”. In December 1997, a second conference took place on “Life Cycle Assessment of Aluminium: Methods and Applications”. In April 1998 the third workshop was held entitled “Methodological Aspects of a Resource-oriented Analysis of Material Flows”. The next conference is planned for December 1998 on “Environmental related Aspects of Aluminium Production”. Finally, a conference on “Methods for an Integrated Evaluation of Material Flows” is under consideration for 1999.     

Current Estimates of the Economic Cost of Obesity in the United States

This study was undertaken to update and revise the estimate of the economic impact of obesity in the United States. A prevalence-based approach to the cost of illness was used to estimate the economic costs in 1995 dollars attributable toobesity for type 2 diabetes mellitus, coronary heart disease (CHD), hypertension, gallbladder disease, breast, endometrial and colon cancer, and osteoarthritis. Additionally and independently, excess physician visits, work-lost days, restricted activity, and bed-days attributable to obesity were analyzed cross-sectionally using the 1988 and 1994 National Health Interview Survey (NHIS). Direct (personal health care, hospital care, physician services, allied health services, and medications) and indirect costs (lost output as a result of a reduction or cessation of productivity due to morbidity or mortality) are from published reports and inflated to 1995 dollars using the medical component of the consumer price index (CPI) for direct cost and the all-items CPI for indirect cost. Population-attributable risk percents (PAR%) are estimated from large prospective studies. Excess work-lost days, restricted activity, bed-days, and physician visits are estimated from 88,262 U. S. citizens who participated in the 1988 NHIS and 80,261 who participated in the 1994 NHIS. Sample weights have been incorporated into the NHIS analyses, making these data generalizable to the U. S. population. The total cost attributable to obesity amounted to $99. 2 billion dollars in 1995. Approximately $51. 64 billion of those dollars were direct medical costs. Using the 1994 NHIS data, cost of lost productivity attributed to obesity (BMI≥30) was $3. 9 billion and reflected 39. 2 million days of lost work. In addition, 239 million restricted-activity days, 89. 5 million bed-days, and 62. 6 million physician visits were attributable to obesity in 1994. Compared with 1988 NHIS data, in 1994 the number of restricted-activity days (36%), bed-days (28%), and work-lost days (50%) increased substantially. The number of physician visits attributed to obesity increased 88% from 1988 to 1994. The economic and personal health costs of overweight and obesity are enormous and compromise the health of the United States. The direct costs associated with obesity represent 5. 7% of our National Health Expenditure in the United States .     

What Is the Economic Case for Treating Obesity?

From both societal and payer perspectives, the economic effect of obesity in the United States is substantial, estimated at approximately 6% of our national health expenditure and cost of care in a major health maintenance organization. The number of physician visits related to obesity has increased 88% in a 6-year period. The morbidity cost (lost productivity) and functional capability of the patient with obesity is increasing rapidly (50% increase in lost productivity, 36% increase in restricted activity, and 28% increase in number of bed-days). Cost savings of treating obesity are comparable to those of treating other chronic diseases such as coronary heart disease and diabetes. Most studies indicate that most of the direct health care costs of obesity are from type 2 diabetes, coronary heart disease and hypertension. To date, however, there have been no published reports of the cost effectiveness of the medical management of obesity treatment. In conclusion, the cost of obesity is comparable to that of other chronic diseases, yet it receives disproportionately less attention. Cost effectiveness studies need to be initiated promptly.     

Single-stage chromatographic clarification of Chinese Hamster Ovary cell harvest reduces cost of protein production

A single-stage clarification was developed using a single-use chromatographic clarification device (CCD) to recover a recombinant protein from Chinese Hamster Ovary (CHO) harvest cell culture fluid (HCCF). Clarification of a CHO HCCF is a complex and costly process, involving multiple stages of centrifugation and/or depth filtration to remove cells and debris and to reduce process-related impurities such as host cell protein (HCP), nucleic acids, and lipids. When using depth filtration, the filter train consists of multiple filters of varying ratios, layers, pore sizes, and adsorptive properties. The depth filters, in combination with a 0.2-micron membrane filter, clarify the HCCF based on size-exclusion, adsorptive, and charge-based mechanisms, and provide robust bioburden control. Each stage of the clarification process requires time, labor, and utilities, with product loss at each step. Here, use of the 3M™ Harvest RC Chromatographic Clarifier, a single-stage CCD, is identified as an alternative strategy to a three-stage filtration train. The CCD results in less overall filter area, less volume for flushing, and higher yield. Using bioprocess cost modeling, the single-stage clarification process was compared to a three-stage filtration process. By compressing the CHO HCCF clarification to a single chromatographic stage, the overall cost of the clarification process was reduced by 17%–30%, depending on bioreactor scale. The main drivers for the cost reduction were reduced total filtration area, labor, time, and utilities. The benefits of the single-stage harvest process extended throughout the downstream process, resulting in a 25% relative increase in cumulative yield with comparable impurity clearance.     

Root vascular anatomy predicts maximum growth rates in savanna trees and grasses

Root-based functional traits are relatively overlooked as drivers of savanna plant community dynamics, an important gap in water-limited ecosystems. Recent work has shed light on patterns of trait coordination in roots, but less is known about the relationship between root functional traits, water acquisition, and plant demographic rates. Here, we investigated how fine-root vascular and morphological traits are related in two dominant PFTs (C₃ trees and C₄ grasses from the savanna biome), whether root traits can predict plant relative growth rate (RGR), and whether root trait multivariate relationships differ in trees and grasses. We used root data from 21 tree and 18 grass species grown under greenhouse conditions, and quantified a suite of vascular and morphological root traits. We used a principal components analysis (PCA) to identify common axes of trait variation, compared trait correlation matrices between the two PFTs, and investigated the relationship between PCA axes and individual traits and RGR. We found that there was no clear single axis integrating vascular and morphological traits, but found that vascular anatomy predicted RGR in both trees and grasses. Trait correlation matrices differed in trees and grasses, suggesting potentially divergent patterns of trait coordination between the two functional types. Our results suggested that, despite differences in trait relationships between trees and grasses, root conductivity may constrain maximum growth rate in both PFTs, highlighting the critical role that water relations play in savanna vegetation dynamics and suggesting that root water transport capacity is an important predictor of plant performance in the savanna biome.     

广东森林和野生动物自然保护区生态经济持续发展探讨

本文总结了广东森林和野生动物自然保护区的建设和发展,从生态经济学原理和广东实际情况出发,探讨自然保护区生态经济的持续发展,并以车八岭国家级自然保护区为例,论述自然保护区持续发展的经营管理实践与经验。     

Endangered fishes and economics: intergenerational obligations

Synopsis The diversity of fishes is declining worldwide, largely as the result of habitat alterations created by decisions that foster short-term economic gain. While the best arguments for preserving endangered fishes and ecosystems are non-economic arguments, they have been relatively ineffective. Therefore, it is necessary to provide economic arguments as well. Fish in general have high market values and are a vital source of protein for humans but these values have contributed more to their decline than to their conservation. Fish also have high value as indicators of the health of ecosystems which provide many services to humans, such as clean water. This has not prevented the degradation of aquatic ecosystems, although the value of fisheries has occasionally justified ecosystem protection. Existence values have been developed as a way of putting an economic value on some of the less tangible aspects of fish and ecosystems but they also make it possible to justify extinctions. If the continuous increase in the number of endangered fishes and aquatic ecosystems is to be halted, then the economic costs of environmental degradation to future generations must be included as part of the cost of doing business today (intergenerational value). Political action is needed to protect fishes and aquatic habitats against the day when more benign economic and philosophical systems become predominant.Invited essay     

Implications of host mortality on the economics of Fopius arisanus (Hymenoptera: Braconidae) mass rearing

Fopius (= Biosteres) arisanus (Sonan) (= Opius oophilus Fullaway) is an egg-pupal parasitoid of tephritid fruit flies. Our breakthrough in the development of a laboratory-adapted strain of F. arisanus facilitated insectary rearing of parasitoids in large numbers. First colonized in captivity in 1989, F. arisanus has been reared routinely on the oriental fruit fly, Bactrocera (= Dacus) dorsalis (Hendel), its natural host. Parasitization by F. arisanus results in the latent death of developing hosts. Host mortality data are presented in a life table to estimate cost of parasitization on the economics of F. arisanus mass rearing. Percent kills of 10, 32, and 76% exerted by F. arisanus on the egg, larval, and pupal stages of the rearing hosts, respectively, resulted in a mean parasitoid recovery of 23.6%. The production cost was estimated by integrating life table data with the costs of rearing supplies and materials and personnel-hours requirements. Production of 1 million parasitoid adults requires the exposure of 4.2 million B. dorsalis eggs (= propagation hosts). We estimated the cost of producing 1 million parasitoids to be $2,363.30 and identified the most expensive aspects of F. arisanus rearing. Recommendations for streamlining the rearing process to reduce costs are provided.     

叶菜类蔬菜害虫生态控制系统组建及其效益评价

运用种群系统控制的原理与方法,组建了叶菜类蔬菜主要害虫生态控制体系,用环境经济学方法评价了系统中生态控制技术应用于生产的实际效果,并与化学防治条件下的效益进行了比较。结果表明,采用生态控制的方法,其经济效益、社会效益和环境效益远远高于化学防治。