Assessing optimal configurations of multi-paddock grazing strategies in tallgrass prairie using a simulation model.

Maintaining or enhancing the productive capacity and resilience of rangeland ecosystems is critical for the continued support of livelihoods and the ecosystem services that benefit society at large. While the benefits of multi-paddock grazing management have been evident for many years in many countries, it is extremely difficult if not impossible to adequately assess the consequences of the different combinations of management options possible when using multi-paddock management under constantly varying conditions on rangelands. To investigate grazing scenarios that would be impractical to conduct in the field we developed a simulation model to focus on addressing the impacts of different cattle grazing management options with multi-paddock management on ecological condition (EC) and profitability. Cattle ranching options are simulated over 25 years periods under varying levels of multi-paddock grazing management complexity at low to moderate stocking levels and fixed or variable stocking rates. We examine the likely ecological and economic effects of shortening grazing periods, lengthening recovery periods, using fixed versus adaptive operational decisions and increasing the number of paddocks in the grazing configuration. At initial stocking levels of up to at 70% of forage standing crop, both EC and profitability are increased with increasing number of paddocks. Shorter periods of grazing increase both EC and profitability while increasing recovery periods increases both EC and profitability initially but profitability decreases if recovery periods are too long. Both EC and profitability are positively related to number of paddocks used.

Recirculating vertical flow constructed wetland: green alternative to treating both human and animal sewage.

Subsurface constructed wetlands using a recirculating vertical flow are a viable alternative technology to pretreating conventional residential septic systems effluents before underground discharge. The authors examined performance of a recirculating vertical flow constructed wetland (RVFCW) to treat both human and domestic animal sewage from the LaGrange County (Indiana) Animal Shelter. Effluent water samples were analyzed for the five-day biochemical oxygen demand (BOD5), total suspended solids (TSS), ammonia-nitrogen (AN), total Kjeldhal nitrogen (TKN), total nitrogen (TN), nitrate-nitrogen, total phosphorus (TP) and fecal coliform bacteria (FC). Treatment efficiencies (percentage removal) after a two-year operation were high for BOD5 (99%), TSS (98%), AN (96%), TKN (94%), TN (83%), and FC (99%). Nitrate-nitrogen final mean value was 6.8 mg/L, dissolved oxygen concentration increased from 1.8 to 4.3 mg/L, and removal efficiency for total phosphorus was low (33%). These results show that vertical flow constructed wetlands are a green alternative to remove pollutants generated for both human and domestic animals.

What influences family physicians' cancer screening decisions when practice guidelines are unclear or conflicting?

OBJECTIVES: To determine (a) the respondents' perceptions of 4 unclear or conflicting cancer screening guidelines: prostate-specific antigen (PSA) for men over 50, mammography for women 40-49, colorectal screening by fecal occult blood testing (FOBT), and colonoscopy for patients over 40; and (b) the influence of various factors on the decision to order these tests. STUDY DESIGN: National Canadian mail survey of randomly selected family physicians. POPULATION: Family physicians in active practice (n=565) selected from rural and urban family medicine sites in 5 provinces representing the main regions in Canada. OUTCOME MEASURED: Agreement with guideline statements, and decision to order screening test in 6 clinical vignettes. RESULTS: Of 565 surveys mailed, 351 (62.1%) were returned. Most respondents agreed with the Canadian Task Force recommendations, and most believed that various guidelines for 3 of the 4 screens were conflicting (PSA 86.6%; mammography 67.5%; FOBT 62.4%). Patient anxiety about cancer, patient expectations of being tested, and a positive family history of cancer increased the odds that the 4 tests would be ordered. A good quality patient-MD relationship decreased the odds of ordering a mammogram. Screening decisions were also significantly influenced by the respondents' beliefs about whether screening was recommended and whether screening could cause more harm than good. A physician's sensitivity to his or her colleagues' practice influenced screening decisions regarding PSA and mammography. CONCLUSIONS: These results suggest a conceptual framework for understanding the determinants of screening behavior when guidelines are unclear or conflicting.