Dosimetric impact of flattening filter and flattening filter-free beams on IMRT planning of NSCLC

CARO 2016 Annual Scientific Meeting, "Quality and Safety in Radiation Oncology", September 14-17, 2016, Banff, AB202101 bcrcVersion of RecordPublishe

The effect of water table decline on plant biomass and species composition in the Zoige peatland: A four-year in situ field experiment

The Zoige peatland is the largest alpine peatland in the world, and it is suffering the threat of water table decline. Plant productivity and species composition are important to ecosystem carbon sequestration and soil carbon input in peatlands. We examined the responses of plant community composition and biomass accumulation to water table decline to better understanding the responses of this peatland to environmental changes. A four-year in situ field experiment was conducted involving three treatments: deep, shallow, and control water tables, which were achieved by experimental drainage with 50 cm, 20 cm, and 0 cm deep ditches, respectively. Experimental drainage decreased the annual mean height of water table by ca. 12 cm and 15 cm (relative to the control) in the shallow and deep water table treatments, respectively, over the four years. The response of aboveground plant biomass (APB) to water table decline declined in the first year, remained unchanged in the second year and increased during the third and fourth years. However, water table decline had a non-significant effect on belowground plant biomass. This duration-dependent response of APB can be attributed to the changes in community species composition during the study years. Specifically, the negative effect of water table decline in the first year was due to the significant decrease in APB of hygrophytes (sedges and rushes). In the second year, although water table decline significantly increased APB of mesophytes (grasses and forbs), this increase was offset by the decrease in APB of hygrophytes, leading to a neutral effect. In both the third and fourth years, the extent of the increase in APB of mesophytes (typically the forb species Anemone trullifolia var. linearis) was greater than that of the decrease in APB of hygrophytes, leading to a positive effect. Our results indicate that short-term decline of the water table may increase the primary productivity by shifting dominant species of hygrophytes to mesophytes in the Zogie peatland

The effect of water table decline on soil CO2 emission of Zoige peatland on eastern Tibetan Plateau: A four-year in situ experimental drainage

Water table decline is a major threat to soil organic carbon in peatlands worldwide principally because it may largely increase soil CO2 emission (SCE). This study is to determine the response of SCE to water table decline in the Zoige peatland of Tibetan Plateau, which has experienced rapid decline of water table due to climate change and anthropogenic drainage. We conducted a field in situ drainage experiment consisting of low (plots surrounded by 50 cm deep ditches), intermediate (20 cm deep) and high (intact) water table levels. The experiment lasted for about four years, during which we measured SCE rate and associated variables including soil temperature and moisture with a higher frequency in the growing season (May-September) than the non-growing season (October-April). Experimental drainage decreased water table height by ca. 12 cm and 15 cm (relative to the intact) and soil moisture (at 5 cm soil) by 6% and 12% (relative to 45% in the intact) on average in intermediate and low water table treatments, respectively, but it did not affect soil temperature during the experimental years. The effect of drainage on SCE varied with season. In the non-growing season, the drainage effect was nonsignificant in each measurement possibly because the low-temperature effect overrode the drainage effect on SCE. In the growing season, the drainage mostly increased the emission except for several cases, in which a negative effect was observed. The negative effect of drainage could be due to the low soil moisture (< 25%) in the drained treatments. Provided that the magnitude and the duration of the SCE increase were greater than those of the decrease, it can be estimated that drainage increased SCE by 17% and 20% on average in the low and the intermediate water table treatments, respectively, over the experimental years. Our results suggest that water table decline may facilitate net carbon emission and hence decrease soil carbon storage in the Zoige peatland. We call for artificial filling of the ditches that were historically created by both human beings and storm waters to increase water table in the Zoige peatland

Radiographic versus ultrasound evaluation of the Risser Grade in adolescent idiopathic scoliosis: a prospective study of 46 patients

The determination of skeletal age is essential in the management of patients with scoliosis. One of the most frequently used techniques to determine skeletal maturity is the method described by Risser. However, repeated X-ray exposure in the follow-up examinations of scoliosis patients may increase the risk of cancer. We compared conventional radiological evaluation of the Risser grade with ultrasound evaluation. For scoliosis patients routine application of ultrasound in the follow-up examinations may significantly reduce radiation exposure. 46 adolescent idiopathic scoliosis patients (median age, 14.5 years) were investigated. Sonographic and radiographic assessment of Risser sign was carried out by two independent senior staff skeletal radiologists. Agreement of Risser Grade between the two diagnostic methods was determined by Kappa statistics. Coefficients <0.21, 0.21–0.40, 0.41–0.60, 0.61–0.80, and >0.80 were rated as poor, fair, moderate, good, and very good agreement. For Risser Grades I–III 100% agreement was found between the two methods. Disagreement between radiographic and sonographic evaluation was found in Risser Grades IV and V. In five patients, X-ray evaluation yielded Risser Grade V while ultrasound showed Risser Grade IV. In one patient, radiographic examination resulted in Risser Grade IV while Grade V was detected in ultrasound. Overall, the Kappa value showed very good agreement between the two diagnostic methods. Our findings suggest that ultrasound can be applied as an alternative method to X-ray evaluation in Risser Grade determination. It should be routinely used in clinical practice to reduce the patients exposure to radiation