Prenatal diagnosis of 49,XXXYY

The first prenatally diagnosed case of 49,XXXYY is reported. The pathological findings of the fetus included bilateral clinodactyly, decreased carrying angles (OO), and hypertelorism, slightly low set ears and mildly prominent forehead. A minimum of two independent non- disjunctional events are postulated for this polysomy to arise.     

Managing for biodiversity: Emerging ideas for the electric utility industry—summary statement

The conference entitled Managing for Biodiversity: Emerging Ideas for the Electric Utility Industry was held in Williamsburg, Virginia, USA, during 19–20 March 1996. This paper provides an overview of the key points, conclusions, and recommendations from both the presentations/papers and the discussions throughout the conference.     

Infrared observations of H II regions

For many years emission nebulae like the Great Nebula in Orion were considered essentially as ionized hydrogen clouds (HII regions) to be understood with the methods of plasma physics. Infrared observations at wavelengths between 1 and 20 μm from the ground, and in the far infrared (20 μm-1 mm) from above the atmosphere, have shown these regions to be strong infrared emitters. This radiation is due to thermal emission of dust mixed with the gas and heated by hot young stars. HII regions indicate recent star formation, and close to these regions many other signposts of early stellar development can be studied in the infrared.     

Temporal variability of the elemental composition in urban street dust

Urban Street dust is recognized as a source of urban air and runoff degradation. This paper takes a preliminary step toward a better understanding of temporal variability in street dust chemistry and of the controlling mechanisms. Street dust samples, collected over four seasons in the city of Hamilton, Canada, show a variability dependent on element and source-anthropogenic sources exhibiting the greatest temporal variability. In addition, elements attributed to common sources exhibit similar temporal patterns. The use of generic or even one-time samples may seriously misrepresent the elemental make-up of urban street dust. Based on the samples collected in this study, a number of questions/insights are posed to further the study of street dust temporal variability.     

Effects of engine speed and accessory load on idling emissions from heavy-duty diesel truck engines

A nontrivial portion of heavy-duty vehicle emissions of NOx and particulate matter (PM) occurs during idling. Regulators and the environmental community are interested in curtailing truck idling emissions, but current emissions models do not characterize them accurately, and little quantitative data exist to evaluate the relative effectiveness of various policies. The objectives of this study were to quantify the effect of accessory loading and engine speed on idling emissions from a properly functioning, modern, heavy-duty diesel truck and to compare these results with data from earlier model year vehicles. It was found that emissions during idling varied greatly as a function of engine model year, engine speed, and accessory load conditions. For the 1999 model year Class 8 truck tested, raising the engine speed from 600 to 1050 rpm and turning on the air conditioning resulted in a 2.5-fold increase in NOx emissions in grams per hour, a 2-fold increase in CO2 emissions, and a 5-fold increase in CO emissions while idling. On a grams per gallon fuel basis, NOx emissions while idling were approximately twice as high as those at 55 mph. The CO2 emissions at the two conditions were closer. The NOx emissions from the 1999 truck while idling with air conditioning running were slightly more than those of two 1990 model year trucks under equivalent conditions, and the hydrocarbon (HC) and CO emissions were significantly lower. It was found that the NOx emissions used in the California Air Resources Board's (CARB) EMFAC2000 and the U.S. Environmental Protection Agency's (EPA) MOBILE5b emissions inventory models were lower than those measured in all of the idling conditions tested on the 1999 truck.     

Aerially guided leak detection and repair: A pilot field study for evaluating the potential of methane emission detection and cost-effectiveness

Novel aerial methane (CH₄) detection technologies were used in this study to identify anomalously high-emitting oil and gas (O&G) facilities and to guide ground-based “leak detection and repair” (LDAR) teams. This approach has the potential to enable a rapid and effective inspection of O&G facilities under voluntary or regulatory LDAR programs to identify and mitigate anomalously large CH₄ emissions from a disproportionately small number of facilities. This is the first study of which the authors are aware to deploy, evaluate, and compare the CH₄ detection volumes and cost-effectiveness of aerially guided and purely ground-based LDAR techniques. Two aerial methods, the Kairos Aerospace infrared CH₄ column imaging and the Scientific Aviation in situ aircraft CH₄ mole fraction measurements, were tested during a 2-week period in the Fayetteville Shale region contemporaneously with conventional ground-based LDAR. We show that aerially guided LDAR can be at least as cost-effective as ground-based LDAR, but several variable parameters were identified that strongly affect cost-effectiveness and which require field research and improvements beyond this pilot study. These parameters include (i) CH₄ minimum dectectable limit of aerial technologies, (ii) emission rate size distributions of sources, (iii) remote distinction of fixable versus nonfixable CH₄ sources (“leaks” vs. CH₄ emissions occurring by design), and (iv) the fraction of fixable sources to total CH₄ emissions. Suggestions for future study design are provided.

Implications: Mitigation of methane leaks from existing oil and gas operations currently relies on on-site inspections of all applicable facilities at a prescribed frequency. This approach is labor- and cost-intensive, especially because a majority of oil and gas–related methane emissions originate from a disproportionately small number of facilities and components. We show for the first time in real-world conditions how aerial methane measurements can identify anomalously high-emitting facilities to enable a rapid, focused, and directed ground inspection of these facilities. The aerially guided approach can be more cost-effective than current practices, especially when implementing the aircraft deployment improvements discussed here.     

A simple method for estimating dermal absorption of chemicals in water

A semiempirical mathematical model is proposed for estimating the dermal absorption of chemicals from dilute aqueous solutions, such as bath water. Absorption depends on the concentration of the chemical in water, the area of skin exposed, the time of exposure, and a permeation coefficient that depends importantly on the relative solubility of the material in lipids and water, among other factors not so easily modeled.     

Spacing and distribution of bowers in Macgregor's Bowerbird (Amblyornis macgregoriae)

Summary Bowerbirds (Ptilonorhynchidae) have been described as exhibiting exploded lek mating patterns. Quantitative documentation and analysis of spatial dispersion, however, is lacking for most species despite its importance to a fundamental understanding of social organization. We studied Macgregor's Bowerbird (Amblyornis macgregoriae) in eastern New Guinea in 1980 and 1981 to quantify spatial distribution and selection of bower sites in relation to ecological and social factors. Forty-two bower sites were located in approximately 750 ha of mid-montane forest. They were linearly and regularly spaced along ridges with a mean inter-bower distance of 169±64 m SD (range 75–348 m). Statistical analysis showed males to be regularly spaced within available habitat. Discriminant analysis of seven habitat variables measured along utilized ridge lines showed that bower sites differed significantly from potentially available sites with respect to slope and width of ridge, closure of canopy, and density of saplings. Placement of bowers with respect to these factors was not correlated with inter-bower distance. Most males maintained only one bower; four (10%) maintained two bowers simultaneously. Males spent an average of 54% of daylight hours within an activity center of 15–20 m radius surrounding the bower and aggressively defended this area against conspecific males. Marauding pressure on bowers was high, and 39% of all observed mating attempts (n=18) were disrupted by neighboring males. Macgregor's Bowerbird exhibits a social system that appears to be intermediate between lek behavior and territoriality, combining the social dynamics and opportunism of the former and the uniform field of display sites and nests of the latter. We hypothesize that dispersion in this species is partly due to males buffering their display space against intruder pressure. We suggest that strict adherence to the dispersion criterion in classifying promiscuous mating systems may be inappropriate.