A Framework for Geographically Sensitive and Efficient Recycling Networks

This paper has three primary objectives. First, it seeks to demonstrate that recycling is an important component of sustainable human systems, particularly in the case of electronics, where environmental impacts of disposal are potentially severe. Second, it presents a methodology that could be used to estimate the volumes of electronics or other consumer durable goods that are available for recycling. Third and last, it illustrates, through a case study of Atlanta focused on computers, that metropolitan areas may fruitfully be viewed as opportune centres from which to mine, recycle and reuse cast-off electronic goods. From an environmental and economic development policy perspective, doing so presents an important opportunity to provide new economic opportunities in the most distressed portions of metropolitan areas which have been disproportionately impacted by previous environmentally destructive industrialization practices.     

Analytic Extensions of the Gaussian Plume Model

The Gaussian Plume Model is extended to provide analytic characterizations of (a) the dispersion parameters; (b) the Gaussian Plume Model in polar coordinates; (c) the wind rose in direction and velocity space; and (d) the impact of dispersion upon wind rose patterns. The final analytic result should facilitate the estimation of the impact of changes in source emissions upon ground level pollution concentrations and thus extend the calculational speed and usefulness of the Gaussian Plume Model.     

Internal dispersal of seeds by waterfowl: effect of seed size on gut passage time and germination patterns

Long distance dispersal may have important consequences for gene flow and community structure. The dispersal of many plants depends on transport by vertebrate seed dispersers. The shapes of seed shadows produced by vertebrates depend both on movement patterns of the dispersers and on the dynamics and effects of passage through the disperser’s gut (i.e. the retention time, survival and germination of ingested seeds). A combination of experiments with captive waterbirds and aquatic plant seeds was used to analyse the following: (a) the effects of inter- and intra-specific variation in seed size and duck species on seed retention time in the gut and (b) the relationship between retention time and the percent germination and germination rates of seeds. Among the three Scirpus species used, those with smaller seeds showed higher survival after ingestion by birds and longer retention times inside their guts than those with larger seeds. For Potamogeton pectinatus, only seeds from the smaller size class (<8 mg) survived ingestion. Retention time affected the percent germination and germination rate of Scirpus seeds but in a manner that varied for the different plant and bird species studied. We recorded both linear and non-linear effects of retention time on percent germination. In addition, germination rate was positively correlated with retention time in Scirpus litoralis but negatively correlated in Scirpus lacustris. Small seed size can favour dispersal over larger distances. However, the effects of retention time on percent germination can modify the seed shadows produced by birds due to higher percent germination of seeds retained for short or intermediate periods. The changes in dispersal quality associated with dispersal distance (which is expected to be positively related to retention time) will affect the probability of seedling establishment over longer distances and, thus, the spatial characteristics of the effective seed shadow.     

Diagnosis and significance of cystic hygroma in the first trimester

Thirty cases of cervical cystic hygroma were diagnosed in the first trimester of pregnancy. Karyotype analysis was available in 29 (97 per cent). Fifteen (52 per cent) had a chromosomal abnormality. The ultrasound appearance was described as posterior cervical, lateral cervical, or cervical hygroma with hydrops. Of the 14 euploid embryos, six were electively aborted, two are undelivered, and six have been delivered as phenotypically normal infants. In cases in which the chromosomes were normal and the pregnancy continued, all lesions resolved by 18 weeks.     

Domestic waste recovery by Local Authorities in the UK: a background to the Green Paper

The recent Green Paper ‘War on Waste’ urges local authorities to organize the recovery and re-use of waste materials in their areas. It is ambiguous, however, on the question of whether recovery should be regarded primarily as a commercial venture or a social service. In this article some of the factors to be considered before embarking on a recovery programme are discussed, and the authors identify some of the arguments for and against the view that recovery is properly a local authority service. Questions considered include the costs and savings associated with a recovery scheme, the impact of the activities of opportunists and the role of the private contractor and voluntary organizations.     

Instrument tuning for trace analysis of dioxins and furans for the vg 70s/se gas chromatography/mass spectrometry system using electron impact mode

We present the salient characteristics of tuning procedures that have evolved from our 3 years of experience while producing large amounts of data of the highest quality. Our laboratory routinely analyzes 2,3,7,8‐substituted dioxins and furans at parts per quadrillion levels in 50–100 g of human serum samples using the VG 70S/SE stand‐alone gas chromatography/mass spectrometry (GC/MS) system at 10000 resolution (defined by 5% overlap) in the selected ion recording mode. Trace measurement of dioxins and furans in human biological matrices—for example, whole blood, serum, or adipose tissue‐requires reproducible instrument tuning within day as well as among days for quality results. Additionally, instument‐tuning procedures among operators must be reproducible to minimize operator bias because periodically different operators are used. Instrument tuning is highly subjective and argumentive; therefore, to minimize the ambiguity within our laboratory, we have standardized our technique to reproducibly tune the GC/MS system.