Search

By reference to examples in the UK this paper examines the wildlife potential of reedbed treatment systems, both in their ability to act as pollutant buffers to protect or create downstream wetlands of conservation importance and as wildlife resources in their own right. The constraints of size, structural diversity, pollution stresses and design criteria of constructed wetlands are evaluated in terms of wildlife conservation opportunities, and the more stringent water quality requirements for wildlife functions are discussed. As a case study example, the paper examines in detail the South Finger Reedbed developed by The Wildfowl & Wetlands Trust. This system has been designed with the dual objectives of improving the quality of effluent from a large collection of captive wildfowl in order to buffer sensitive downstream wetlands and of creating a wetland habitat of nature conservation value. The performance of this system, constructed in 1993, indicates good treatment levels, with suspended solids reduction around 80% and BOD generally above 60%. In terms of wildlife performance the system rapidly evolved to support a broad range of vertebrate and invertebrate species. The paper concludes that constructed wetlands for waste water treatment can be designed and managed to achieve optimal wildlife potential if approached from an ecological perspective as opposed to a strictly engineering viewpoint.

Over the last two decades in India there have been large increases in outsourced jobs and large increases in schooling rates, particularly in English. Existing evidence suggests the trends are broadly related. In this paper we explore how localized these impacts are; this has implications for understanding how quickly information about these jobs diffuses. We use panel data on school enrollment from a comprehensive school-level administrative dataset. This is merged with detailed data on Information Technology Enabled Services (ITES) center location and founding dates. Using school fixed effects, we estimate the impact of introducing a new ITES center in the vicinity of the school on enrollment. We find that introducing a new ITES center results in a 5.7% increase in number of children enrolled; these effects are extremely localized. We argue this result is not driven by pre-trends in enrollment or endogenous center placement, and is not a result of ITES-center induced changes in population or increases in income. The effect is driven entirely by English-language schools, consistent with the claim that the impacts are driven by changes in returns to schooling.

Over the last two decades in India there have been large increases in outsourced jobs and large increases in schooling rates, particularly in English. Existing evidence suggests the trends are broadly related. In this paper we explore how localized these impacts are; this has implications for understanding how quickly information about these jobs diffuses. We use panel data on school enrollment from a comprehensive school-level administrative dataset. This is merged with detailed data on Information Technology Enabled Services (ITES) center location and founding dates. Using school fixed effects, we estimate the impact of introducing a new ITES center in the vicinity of the school on enrollment. We find that introducing a new ITES center results in a 5.7% increase in number of children enrolled; these effects are extremely localized. We argue this result is not driven by pre-trends in enrollment or endogenous center placement, and is not a result of ITES-center induced changes in population or increases in income. The effect is driven entirely by English-language schools, consistent with the claim that the impacts are driven by changes in returns to schooling.

BACKGROUND--Pneumocystis carinii pneumonia was thought to occur from reactivation of latent infection, but recent studies with the polymerase chain reaction have failed to detect P carinii in normal subjects. If pneumocystis pneumonia is therefore caused by new infection the source and mode of transmission of P carinii remains unknown. METHODS--Natural exposure to P carinii was detected by measuring antibodies by indirect immunofluorescence in 24 health care workers working continuously with patients with AIDS and 24 control health care workers exclusively treating elderly patients. RESULTS--P carinii antibody titres were significantly higher in the health care workers exposed to AIDS than in the control group (median titre 1:32 v 1:16 respectively). Three control subjects had no antibodies compared with none of the subjects exposed to AIDS, and 10 of the 12 highest titres came from the exposed group. CONCLUSIONS--Raised P carinii antibody titres in health care workers caring for patients with AIDS suggest that patients infected with HIV may be a potentially infectious source of P carinii for susceptible subjects.

In two lactation trials we determined if aspen sawdust could be a roughage replacement in high-concentrate dairy rations. In Experiment 1, 20 lactating Holstein cows were separated into four equal groups and fed ad libitum one of the following four all-pelleted rations for a 6-wk experimental period: (1) grain mix with 10% sawdust; (2) grain mix with 10% sawdust, 5% sodium bentonite, and 2% sodium bicarbonate; (3) grain mix with 20% sawdust; or (4) grain mix with 30% sawdust. The four rations did not produce significant differences in milk production, percent milk protein, percent milk solids-not-fat, feed intake, or body weight. Milk fat percent, rumination time (h/day), and ruminal acetate-to-propionate ratios were affected and averaged 2.1, 2.0, 1.24; 2.6, 1.6, 1.75; 2.8, 3.2, 1.58; and 3.7, 4.1, 2.60 for each of the four groups. Experiment 2 was similar to Experiment 1 except 12 lactating cows were separated into three equal groups; each group was fed one of the following three rations during the experimental period: (1) grain mix with 2.3 kg alfalfa hay; (2) grain mix with 12% sawdust and 2.3 kg hay; or (3) grain mix with 12% sawdust, 5% sodium bentonite, 2% sodium bicarbonate, and 2.3 kg hay. Effects of treatment were not significant on milk production or composition, feed intake, or body weight. Milk fat percent, rumination time (h/day), and ruminal acetate-to-propionate ratios averaged 3.4, 5.1, 1.81; 3.5, 6.3, 2.17; and 3.6, 5.1, 3.43, respectively. Aspen sawdust can be a partial roughage substitute in lactating dairy cow rations, and it is helpful in maintaining near-normal milk fat content in high-concentrate rations. The sawdust cannot, however, serve as the only source of roughage for lactating cows because of the irregular feed intake that results if no other forage is fed.

Twelve lactating cows divided into three groups of four were fed either equal parts of hay and pelleted concentrate (A), limited hay and pelleted concentrate containing 32% aspen sawdust (B), or limited hay and pelleted concentrate (C), to determine if aspen sawdust could serve as a partial roughage substitute in a high-concentrate ration. There were no significant ration effects on milk production or per cent milk protein. Adjusted means of 2.59, 3.13, and 1.67 for per cent milk fat for Rations A, B, and C were significantly different. Adjusted ruminal acetate: propionate ratios were 3.99, 2.70, and 1.27 for Rations A, B, and C. Time spent ruminating was highest for cows fed Ration B, followed by Rations A and C (5.8, 5.3, and 3.3 hr/day). Dry matter intakes of hay and concentrate on Rations A, B, and C were 7.3 and 7.8, 2.0 and 14.9, and 1.9 and 12.4kg, respectively. Cows receiving Ration B (with aspen) compensated for the lower digestibility of this ration by eating more of it. Thirty per cent dietary aspen sawdust was effective as a partial roughage substitute for hay.