Responses of runoff and sediment yield to slope length and gravel content of Lou soil engineering accumulation slope in Guanzhong region, Northwest China

With the economic development, a large number of engineering accumulation bodies with Lou soil as the main soil type were produced in Guanzhong area, Northwest China. We examined the characteristics of runoff and sediment yield of Lou soil accumulation bodies with earth (gravel content 0%) and earth-rock (gravel content 30%) under different rainfall intensities (1.0, 1.5, 2.0, 2.5 mm·min-1) and different slope lengths (3, 5, 6.5, 12 m) by the simulating rainfall method. The results showed that runoff rate was relatively stable when rainfall intensity was 1.0-1.5 mm·min-1, while runoff rate fluctuated obviously when rainfall intensity was 2.0-2.5 mm·min-1. The average runoff rate varied significantly across different rainfall intensities on the same slopes, and the difference of average runoff rate of the two slopes was significantly increased with rainfall intensity. Under the same rainfall intensity, the difference in runoff rate between the slope lengths of the earth-rock slope was more obvious than that of the earth slope. When the slope length was 3-6.5 m, flow velocity increased rapidly at first and then increased slowly or tended to be stable. When the slope length was 12 m, flow velocity increased significantly. In general, with the increases of rainfall intensity, inhibition effect of gravel on the average flow velocity was enhanced. When rainfall intensity was 2.5 mm·min-1, the maximum reduction in the average flow velocity of earth-rock slope was 61.5% lower than that of earth slope. When rainfall intensity was less than 2.0 mm·min-1, sediment yield rate showed a trend of gradual decline or stable change, while that under the other rainfall intensities showed a trend of rapid decline and then fluctuated sharply. The greater the rainfall intensity, the more obvious the fluctuation. There was a significant positive correlation between the average sediment yield rate and runoff parameters, with the runoff rate showing the best fitting effect. Among the factors, slope length had the highest contribution to runoff velocity and rainfall erosion, which was 51.8% and 35.5%, respectively. This study can provide scientific basis for soil and water erosion control of engineering accumulation in Lou soil areas.

[Randomized controlled study on the application effect of a new type of intravenous radiofrequency closed therapy system made in China and an imported system]

Objective: To compare the application effect of domestic and imported intravenous radiofrequency closure system in the treatment of primary varicose veins of lower extremities. Methods: This single-center prospective, non-inferiority randomized controlled trial was performed in the Department of Vascular Surgery, the Fourth Affiliated Hospital, Zhejiang University School of Medicine from January 2021 to January 2022. Patients with primary varicose veins of lower extremities who met the ataxation criteria were randomly assigned to the experimental group(domestic novel venous radiofrequency closure system) or the control group(imported venous radiofrequency closure system) in a ratio of 1∶1. The two groups of subjects were compared in terms of target vein closure rate, technical success rate, system operation performance, incidence of adverse events and incidence of serious adverse events(SAE) within 6 months after surgery. Quantitative data were compared by Mann-Whitney U test, and categorical data were compared by χ2 test and non-inferiority test. Results: A total of 80 subjects were included in the trial (41 in the experimental group and 39 in the control group), including 27 males and 53 females, aged (M(IQR)) 55(23) years (range:40 to 78 years). There were 48 cases of left lower limb and 32 cases of right lower limb. The technical success rate and system control performance between the groups were 100%.The incidence of adverse events (58.5% (24/41) vs. 61.5% (24/39), χ2=0.075, P=0.784), and the incidence of SAE (7.3% (3/41) vs. 5.1% (2/39), χ2=0.163, P=0.686) within 6 months after surgery in experimental group and control group had no statistical significance. There was one device-related adverse event in each of the two groups. In the experimental group, one patient developed endovenous heat-induced thrombosis after surgery and recovered after taking rivaroxaban tablets. One patient in the control group had pain in the upper right thigh for more than 1 day after operation, which was cured after using analgesic cream. No device-related SAE occurred. The venous closure rate of the experimental group was 100% (38/38) at 6 months after surgery, and that of the control group was 97.4% (37/38). The difference between the two groups was 2.63% (95%CI:-3.19 to 8.45, Z=4.865, P<0.01), and the 95%CI lower limit of the difference in target venous closure rate between two groups was greater than the non-inferiority threshold of -10.00%. Conclusion: The early application effect of the new domestic intravenous radiofrequency closure system in patients with primary varicose veins of lower extremities is in line with expectations, it is not inferior to the imported system.

Infiltration and shear strength characteristics of gully heads soil of typical vegetation on the gullied Loess Plateau, Northwest China

Gully head is the main active part of gully erosion, which seriously affects the occurrence of gully headcut erosion. To investigate root distribution and soil physical and mechanical characteristics of typical vegetation gully head, we analyzed the infiltration, root distribution, physical and mechanical properties of soil-root complex of soil in different layers (0-1 m) in natural restoration gully head and artificial restoration gully head. The results showed that the variability of soil bulk and total porosity among different vegetation gully heads was low, with bulk density ranging from 1.10 to 1.37 g·cm-3 and total porosity ranging from 48.3% to 58.4%. Infiltration index of different vegetation gully heads generally decreased with increasing soil depth. The infiltration rate of different soil layers in natural restoration gully head tended to stabilize in 20-30 min, while that of artificial restoration gully head tended to stabilize in 40 min. The infiltration capacity and average infiltration rate of artificial restoration gully head were generally higher than those of natural restoration gully head in all soil layers. Root length density, root surface area density, and average diameter all tended to decrease with increasing soil depth. Except for the 20-40 cm soil layer, root length density, root surface area density and average diameter of natural restoration gully head were all lower than those of artificial restoration gully head. Root system of both vegetation gully heads mainly consisted of 0-0.5 mm roots, accounting for 84.2%-93.6% of the total root length. In the vertical depth, with the increases of water content, the cohesion force decreased linearly with the deepening of soil layer, ranging from 0.42 to 22.67 kPa. The average cohesion force of artificial restoration gully head was higher than natural restoration gully head at each level of water content. The study revealed the effects of vegetation on the gully head cut erosion, which could provide scientific basis for the effective prevention and control of soil erosion in the region.

[Effects of gravel content on runoff and sediment yield on Lou soil engineering accumulation slopes under simulated rainfall conditions.]

To investigate the effects of gravel content on runoff and sediment yield on Lou soil accumulation slopes, we conducted indoor simulation rainfall experiments and examined the characteristics of runoff and sediment yield on accumulation slopes with five gravel contents (10%, 20%, 30%, 40%, 50%) under four rainfall intensities (1.0, 1.5, 2.0, 2.5 mm·min^-1), with a no gravels slope as control. The average runoff rate under different test conditions ranged from 2.18 to 13.07 L·min^-1. The average runoff rate was the maximum under the gravel content of 10% (or 20%) and the minimum under the 50% gravel content. The average flow velocity ranged from 0.06 to 0.22 m·s^-1. The variation of flow velocity was complex. The smaller the gravel content, the larger the range of variation and the coefficient of variation. The average flow velocity reached the maximum when the gravel content was 10%. The presence of gravel effectively inhibited the sediment yield, and the sediment reduction benefit reached 84.2%. The rainfall intensity had more influence on the average sediment yield rate than gravel content. Results of partial correlation analysis showed that gravel content was significantly negatively correlated with the ave-rage runoff rate, the average flow velocity, and the average sediment yield rate. The relationships between the ave-rage sediment yield and the average runoff rate, the average flow velocity, and their interaction were all extremely significant linear functions, with the strongest relationship between the average sediment yield and the average runoff rate. This study could provide references for the control of soil erosion and the establishment of erosion models for engineering accumulations in Lou soil areas.

[Characteristics of soil anti-scouribility in gully head wall of grass-covering on the gullied Loess Plateau, Northwest China]

Vegetation restoration in the Chinese Loess Plateau has significantly changed soil erosion process of gully head wall. In order to investigate the characteristics and controlling factors of soil anti-scour properties of gully head covered by grasses, we carried out indoor undamaged soil trench scouring tests. By using barren gully head as the control, the physical and chemical properties and anti-scouring characteristics of soil in different soil layers (0-10, 10-20, 20-40, 40-60, 60-80, 80-100 cm) of the vertical wall of gully with grass cover were analyzed. The results showed that water-stable aggregate content and cohesion in barren and grass-covering gully head decreased with soil depth. Soil organic matter content and soil anti-scouribility coefficient in barren gully head decreased with soil depth, while the two indicators for gully head covered by grass increased firstly and then decreased with soil depth, with the maximum value (24.30 g·kg^-1 and 58.86 L·g^-1) in 10-20 cm soil layer. Meanwhile, the soil anti-scouring coefficient in each soil layer of grass-covering gully head was 1.7-9.3 times of that in soil layer of barren gully head. Soil organic matter content, water-stable aggregate content, cohesion and root length density all presented significantly positive correlation with soil anti-scouribility, among which soil organic matter content had the highest coefficient (r=0.98). Results of this study might provide basic data for the study of headcut erosion mechanism in Loess Plateau gully region, and scientific basis for effective control of soil and water loss in this region.

The implication of diabetes metabolomics in the early diagnosis and pathogenesis of pancreatic cancer

The aim of this study was to analyze metabolite differences in pancreatic cancer and diabetic patients, to better diagnose these diseases. Gas chromatography-mass spectrometry was used to evaluate the metabolomic differences in blood samples of 50 pancreatic patients, 50 diabetic patients and 50 healthy people. Metabonomic data was analyzed with primary component analysis and discriminant analysis. The results show that pancreatic cancer patients, diabetic patients and healthy people can have significantly distinct metabolite profiles. Upregulated metabolites in the serum of the diabetic group included sugars (glucose, fructose), cholesterol, tyrosine and phosphoric acid and other substances, and down-regulation was observed in lactic acid, glycine, alanine, glutamine, proline, citric acid and other substances. It is indicated that identification of the most common changes in specific markers between the two diseases, can provide a new perspective and experimental basis for a better understanding of the metabolic differences and the pathogenesis of the two diseases in future. The present study sheds new light on the diagnosis of pancreatic cancer and diabetes.

Laboratory values improve predictions of hospital mortality

OBJECTIVE

To compare the precision of risk adjustment in the measurement of mortality rates using: (i) data in hospitals' electronic discharge abstracts, including data elements that distinguish between comorbidities and complications; (ii) these data plus laboratory values; and (iii) these data plus laboratory values and other clinical data abstracted from medical records.

DESIGN

Retrospective cohort study.

SETTING

Twenty-two acute care hospitals in St Louis, Missouri, USA.

STUDY PARTICIPANTS

Patients hospitalized in 1995 with acute myocardial infarction, congestive heart failure, or pneumonia (n = 5966).

MAIN OUTCOME MEASURES

Each patient's probability of death calculated using: administrative data that designated all secondary diagnoses present on admission (administrative models); administrative data and laboratory values (laboratory models); and administrative data, laboratory values, and abstracted clinical information (clinical models). All data were abstracted from medical records.

RESULTS

Administrative models (average area under receiver operating characteristic curve=0.834) did not predict death as well as did clinical models (average area under receiver operating characteristic curve=0.875). Adding laboratory values to administrative data improved predictions of death (average area under receiver operating characteristic curve=0.860). Adding laboratory data to administrative data improved its average correlation of patient-level predicted values with those of the clinical model from r=0.86 to r=0.95 and improved the average correlation of hospital-level predicted values with those of the clinical model from r=0.94 for the administrative model to r=0.98 for the laboratory model.

CONCLUSIONS

In the conditions studied, predictions of inpatient mortality improved noticeably when laboratory values (sometimes available electronically) were combined with administrative data that included only those secondary diagnoses present on admission (i.e. comorbidities). Additional clinical data contribute little more to predictive power.