Effective pulmonary ventilation with small-volume oscillations at high frequency

At high oscillation frequencies (4 to 30 hertz), effective alveolar ventilation can be achieved with tidal volumes much smaller than the anatomic dead space. An explanation of this phenomenon is given in terms of the combined effects of diffusion and convection and in terms of data consistent with the hypothesis. Theory and experimental results both show that the significant variable determining the effectiveness of gas exchange is the amplitude of the oscillatory flow rate independent of the individual values of frequency and stroke volume.     

Das landschaftgestaltende Element in der Schädlingsbekämpfung am Beispiel des Stechmückenproblems im Oberrheingebiet

Landscaping as an element of pest control exemplified by the mosquito problem in the upper Rhine area. (An approach te expand scientific thinking) At present, mosquito control in the Upper Rhine area is limited, almost without exception, to the use of insecticides. Howeveer, measures of this type which are contradicting natural process will result only in a temporary reduction of the number of mosquitoes present while contamination of the environment increases. By means of landscaping, a mass development of mosquito species as a pest may be prevented. Although such ?natural” operation, i.e. a re-arrangement of a landscape would mean an alteration, its effect would not be a destroying one.     

Case reports of on-site investigations of auger-related farm injuries

Previous reports have indicated that injuries involving augers (screw conveyors) are a serious problem in agriculture, but to date on-site engineering inspections linking injuries to mechanical and procedural aspects have not been available. This article details four events involving injuries as the result of being entangled in auger flighting. In each report, the circumstances surrounding the injury event are outlined, and the machinery involved is evaluated in terms of its compliance with current safety standards. In three of the four instances, the machinery did not conform to current guarding standards or to safety sign standards. In these three cases, injuries were preventable with improved guarding according to ASAE Standards. In the other case, the machine complied with ASAE Standards, but the injury could have been prevented with improved guarding of the auger flighting.     

Effect of age on hospitalized machine-related farm injuries among the Saskatchewan farm population

Machinery-related injuries are the leading cause of fatal and hospitalized injuries on Canadian farms. In Saskatchewan, the proportion of all farm injuries related to farm machinery exceeds that reported for all of Canada. This project examined the relationship between age and various factors associated with farm machine-related injuries in Saskatchewan. A retrospective review of hospital discharge data from the administrative data set of Saskatchewan Health was conducted using external cause of injury codes to identify cases of farm machinery injury that occurred in Saskatchewan during the period April 1, 1990, to March 31, 2000. Log linear estimates of association of various factors in four age groups were derived. There were 1,493 hospitalizations attributed to farm machinery-related injuries. Among the injured cohort, age was a predictor of the rate of injury. Significant association for nature of injury, mechanism of injury, and type of machine varied by age group. These data provide insights for a case-control study of farm machinery-related injuries with the objective of determining personal, environmental, and machine-related factors that are responsible for this serious public health issue.     

Organic compounds in soils and sediments from unlined waste disposal pits for natural gas production and processing

Samples of soil in dry waste pits and of sediment from waste pits currently in-use for natural gas production in the San Juan Basin of northwest New Mexico were collected for characterization of the presence and concentration of organic compounds. Samples were dried at 25 °C and about 50 g were extracted successively in a Soxhlet apparatus using hexane, benzene, and methanol. Extracts were filtered and condensed to 10 mL. Analyses of hexane extracts of samples using high-resolution gas chromatography showed presence of a complex mixture of 40 to 50 organic compounds in dry soil and in sediment from in-use pits. The range of size for compounds was C₁₀ to C₂₅. Although no compounds were detected in GC analyses of subsequent benzene and methanol extracts of the same soil samples, these extracts were highly colored and contained 5 to 10% of total absorptivity at 254 nm. Total extractable residues in the hexane extracts ranged from 49 to 110 mg g^?1 of soil. Polycyclic aromatic hydrocarbons were detected in hexane extracts at concentrations of 270 to 870μg g^?1 of dry sample.     

Producing the natural fiber naturally: Technological change and the US organic cotton industry

Organic cotton productionboomed in the early 1990s only to fall steeplymid-decade. Production is currently rising, butslowly, and has yet to reach previous levels.This is in marked contrast to the steady growthin organic food production during the 1990s.Why, when other areas of organic productionexperienced steady growth, did organic cottonexperience a boom and bust? A study of thecotton production and processing industryreveals a long and heavily industrializedproduction chain that has presented numerouschallenges to growers and processors trying tointroduce an organic product. In addition, muchof the surge in demand for organic cotton clothoriginated with clothing manufacturersresponding to increased consumer environmentalconcern and interest in improving theirenvironmental reputations. This demandevaporated when clothing companies encountereda lack of consumer awareness of theenvironmental costs of conventional cottonproduction and the benefits of organic cotton.Organic clothing lines were abandoned and manycotton farmers, left with no market for theirorganic bales, were forced to either store thebales or sell them on the conventional marketfor a loss. An examination of the social andtechnical aspects of organic cotton productionidentifies some of the critical variables, suchas the risks farmers face in agriculturalproduction, the organic standards, sources ofinnovation in technological change, and the roleof consumer demand in supporting moresustainable technology, all of which shape thecontinuing development of organic products.     

Tissue Residues of Diuron in Channel Catfish Ictalurus punctatus Exposed to the Algicide in Consecutive Years

In 1999, the United States Environmental Protection Agency granted an emergency exemption under Section 18 of the Federal Insecticide, Fungicide. and Rodenticide Act authorizing the use of the algicide diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] to manage cyanobacterial off-flavors in channel catfish Ictalurus punctcatus . Catfish may remain in ponds for more than one growing season and may therefore be exposed to more than one set of diuron treatments. This study was conducted to determine whether diuron residues in fish carry over from one year to the next and, if so, whether the cumulative exposure causes residues to exceed the tolerance level of 2.0 mg/kg in fillets. Catfish in earthen ponds were exposed to the label-specified treatment protocol of nine consecutive weekly applications of diuron at 0.01 mg/L in the fall of one year and again the following spring. Diuron concentrations in fillets were below limits of detection (0.05 mg/kg) in all fish ( N = 18) prior to the initial diuron treatment series. Immediately after the ninth weekly diuron application in the fall. tissue diuron levels averaged 0.353 mg/kg (pooled SEM = 0.036; range = 0.078–0.724 mg/kg; N = 18). On the day before the second set of diuron treatments 6 mo later. diuron concentrations were below limits of detection in all fish sampled. Immediately after the second set of nine weekly diuron applications, tissue concentrations averaged 0.127 mg/kg (pooled SEM = 0.015; range = not detected to 0.191 mg/kg; N = 18). This study showed that diuron residues in channel catfish were depleted within 2 to 4 mo after exposure to the chemical and there was no carryover of residues in fish from one year to the next. Maximum residue levels in catfish fillets were less than half the tolerance level of 2.0 mg/ kg.     

The humoral immune response of the spiny-tailed agamid lizard (Agama caudospinosum) to injection with Leishmania agamae promastigotes

Spiny-tailed agamid lizards (Agama caudospinosum) were given a single intraperitoneal injection of Leishmania agamae promastigotes. Direct agglutinins (DA), indirect haemagglutinins (IHA) and complement-fixing antibodies (CFA) produced against the parasites were non-precipitating, relatively thermostable and dithiothreitol sensitive. Antibodies were also detected by the immobilisation test (IMM) and by enzyme-linked immunosorbent assay (ELISA). The most sensitive method was the ELISA one. Antibodies were detected 7 days post-injection and maximum IMM (2(-6)), DA (2(-8)), CFA (2(-10)), IHA (2(-12)) and ELISA (2(-16)) titres were obtained from 35 to 49 days. In all cases, the levels of antibody following antigenic stimulation were significantly different from the controls (P less than 0.001). Serum lysozyme levels increased three-fold (P less than 0.001) with the highest value of 46 micrograms/ml occurring after 42 days.