Impacts of cover crops and crop residues on phosphorus losses in cold climates: a review

Non-Peer ReviewedThe use of plants in riparian buffers or cover crops is widely proposed as a strategy to mitigate sediment and nutrient losses from land to water. In cold climates, concerns may arise with regard to potentially elevated phosphorus (P) losses associated with freeze-thaw of plant materials. Here, we review the impacts of cover crops and crop residues on P loss in cold climates, and explore linkages between water extractable P in the plant materials and P loss in surface runoff and subsurface drainage from cropped soils. Water extractable P in plants is greatly affected by crop species and hardiness, as well as freezing regimes including both freezing temperature and the number of freeze-thaw cycles. Although controls on water extractable P in plant tissues and residues are relatively well understood, impacts on P runoff and leaching are inconsistent across studies due to the influences of soil, climate, and management factors. This review sheds light on improving winter crop cover management to minimize P losses from land to water in cold climates and points to future research needs. Specifically, more research is needed to understand interactions between soil, plant, hydrology, and management in influencing P loss, and to improve the assessment of crop contributions to P loss in field settings of cold climates. Further, the trade-offs between the concern over P and the control of sediment loss and nitrogen leaching should be acknowledged, as should the uncertainties of freezing and crop adaptability under future climate regimes

An efficient strategy for evaluating new non-invasive screening tests for colorectal cancer: the guiding principles.

New screening tests for colorectal cancer (CRC) are rapidly emerging. Conducting trials with mortality reduction as the end point supporting their adoption is challenging. We re-examined the principles underlying evaluation of new non-invasive tests in view of technological developments and identification of new biomarkers. A formal consensus approach involving a multidisciplinary expert panel revised eight previously established principles. Twelve newly stated principles emerged. Effectiveness of a new test can be evaluated by comparison with a proven comparator non-invasive test. The faecal immunochemical test is now considered the appropriate comparator, while colonoscopy remains the diagnostic standard. For a new test to be able to meet differing screening goals and regulatory requirements, flexibility to adjust its positivity threshold is desirable. A rigorous and efficient four-phased approach is proposed, commencing with small studies assessing the test's ability to discriminate between CRC and non-cancer states (phase I), followed by prospective estimation of accuracy across the continuum of neoplastic lesions in neoplasia-enriched populations (phase II). If these show promise, a provisional test positivity threshold is set before evaluation in typical screening populations. Phase III prospective studies determine single round intention-to-screen programme outcomes and confirm the test positivity threshold. Phase IV studies involve evaluation over repeated screening rounds with monitoring for missed lesions. Phases III and IV findings will provide the real-world data required to model test impact on CRC mortality and incidence. New non-invasive tests can be efficiently evaluated by a rigorous phased comparative approach, generating data from unbiased populations that inform predictions of their health impact

Open compared with closed haemorrhoidectomy: meta-analysis of randomized controlled trials

Aims: This review compares the most popular techniques in managing the wounds after excisional haemorrhoidectomy, which are either to lay the wounds open or to close them.\ud Methods Randomized controlled trials were identified from the major electronic databases using the search terms “hemorrhoid*” and “haemorrhoid*.” Duration of operation, pain, length of hospital stay, time off work, time for wound healing, patient satisfaction, continence, manometry findings and complications were assessed. Quantitative meta-analysis was performed as appropriate or possible.\ud Results: Six trials including 686 patients met the inclusion criteria. The median follow-up time ranged from 1.5 to 19.5 months. Quantitative meta-analysis showed that there was no significant difference in cure rates between the two techniques (relative risk, 1.4; 95% CI, 0.86 to 2.2; p=0.191). Open haemor-rhoidectomy was more quickly performed (weighted mean difference, 1.03 min; 95% CI, 0.51 to 1.54; p<0.001). Closed haemorrhoidectomy wounds showed faster healing (weighted mean difference, 1.2 weeks; 95% CI, 0.88 to 1.55; p<0.001). Hospital stay, maximum pain score, total and individual complication rates were not significantly different.\ud Conclusions: Apart from faster wound healing after closed haemorrhoidectomy, open and closed techniques appeared equally effective and safe. However, there were only a few studies which presented information in different ways, and statistical heterogeneity was high.\u