ABSTRACT
Objective To explore the technique of maximum entropy model for extracting Oncomelania hupensis snail habi?tats in Poyang Lake zone. Methods The information of snail habitats and related environment factors collected in Poyang Lake zone were integrated to set up the maximum entropy based species model and generate snail habitats distribution map. Two Land?sat 7 ETM+remote sensing images of both wet and drought seasons in Poyang Lake zone were obtained,where the two indices of modified normalized difference water index(MNDWI)and normalized difference vegetation index(NDVI)were applied to ex?tract snail habitats. The ROC curve,sensitivities and specificities were applied to assess their results. Furthermore,the impor?tance of the variables for snail habitats was analyzed by using Jackknife approach. Results The evaluation results showed that the area under receiver operating characteristic curve(AUC)of testing data by the remote sensing?based method was only 0.56, and the sensitivity and specificity were 0.23 and 0.89 respectively. Nevertheless,those indices above?mentioned of maximum en?tropy model were 0.876,0.89 and 0.74 respectively. The main concentration of snail habitats in Poyang Lake zone covered the northeast part of Yongxiu County,northwest of Yugan County,southwest of Poyang County and middle of Xinjian County,and the elevation was the most important environment variable affecting the distribution of snails,and the next was land surface tem?perature(LST). Conclusions The maximum entropy model is more reliable and accurate than the remote sensing?based meth?od for the sake of extracting snail habitats,which has certain guiding significance for the relevant departments to carry out mea?sures to prevent and control high?risk snail habitats.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the cardiac effect of QT interval prolongation in the treatment of acute promyelocytic leukemia (APL) with arsenic trioxide (As(2)O(3)), and the relationship between QT and serum arsenic concentration.</p><p><b>METHODS</b>Blood serum arsenic concentrations of thirty APL patients were determined at 2 hours, 4 hours, 8 hours, and 24 hours after As(2)O(3) injection using atomic fluorophotometry. Cardiac functions were measured simultaneously using a 12-lead body-surface electrocardiogram (ECG). Q-T intervals were manually measured, and then corrected using Bazett's formula (QTc). QT dispersion (QTd) was also calculated. In order to assess the effects of arsenic on the symptoms of anemia, twenty-four anemia patients were divided into two groups on the basis hemoglobin concentration: Group 1 (Hb > or = 90 g/L), and Group 2 (60 g/L < or = Hb < 90 g/L). QTc and QTd of these patients were also manually measured.</p><p><b>RESULTS</b>All QT intervals of APL patients treated with As(2)O(3) injection were prolonged [32.2 ms (27, 41 ms); P < 0.05], but the changes of QTd were not prominent [3 ms (-8, 7 ms), P > 0.05]. There was a delay of 2 hours in maximum QTc following peaks in serum arsenic concentration. Changes in QTc and QTd of the two anemic groups were not prominent.</p><p><b>CONCLUSIONS</b>As(2)O(3) can prolong QTc intervals in APL patients, but the effects are delayed compared to peak serum arsenic concentrations. As(2)O(3) has no prolongation effect on QTd. Mild and moderate anemia do not effect QTc and QTd.</p>