Optimizing the frequency ratio method for landslide susceptibility assessment: A case study of the Caiyuan Basin in the southeast mountainous area of China

Bivariate statistical analysis of data-driven approaches is widely used for landslide susceptibility assessment, and the frequency ratio(FR) method is one of the most popular. However, the results of such assessments are dominated by the number of classes and bounds of landslide-related causative factors, and the optimal assessment is unknown. This paper optimizes the frequency ratio method as an example of bivariate statistical analysis for landslide susceptibility mapping based on a case study of the Caiyuan Basin, a region with frequent landslides, which is located in the southeast coastal mountainous area of China. A landslide inventory map containing a total of 1425 landslides(polygons) was produced, in which 70% of the landslides were selected for training purposes, and the remaining were used for validationpurposes. All datasets were resampled to the same 5 m × 5 m/pixel resolution. The receiver operating characteristic(ROC) curves of the susceptibility maps were obtained based on different combinations of dominating parameters, and the maximum value of the areas under the ROC curves(AUCs) as well as the corresponding optimal parameter was identified with an automatic searching algorithm. The results showed that the landslide susceptibility maps obtained using optimal parameters displayed a significant increase in the prediction AUC compared with those values obtained using stochastic parameters. The results also showed that one parameter named bin width has a dominant influence on the optimum. In practice, this paper is expected to benefit the assessment of landslide susceptibility by providing an easy-to-use tool. The proposed automatic approach provides a way to optimize the frequency ratio method or other bivariate statistical methods, which can furtherfacilitate comparisons and choices between different methods for landslide susceptibility assessment.

Post-earthquake Rainfall-triggered Slope Stability Analysis in the Lushan Area

The "4.20" Lushan earthquake in Sichuan province, China has induced a large amount of geological hazards and produced abundant loose materials which are prone to post-earthquake rainfalltriggered landslides. A detailed landslide inventory was acquired through post-earthquake emergent field investigation and high resolution remote sensing interpretation. The rainfall analysis was conducted using historical rainfall records during the period from 1951 to 2010. Results indicate that the average annual rainfall distribution is heterogeneous and the largest average annual rainfall occurs in Yucheng district. The Stability Index MAPping(SINMAP)model was adopted to assess and analyze the postearthquake slope stability under different rainfall scenarios(light rainfall, moderate rainfall, heavy rainfall, and rainstorm). The model parameters were calibrated to reflect the significant influence of strong earthquakes on geological settings. The slope stability maps triggered by different rainfall scenarios wereproduced at a regional scale. The effect of different rainfall conditions on the slope stability is discussed.The expanding trend of the unstable area was quantitatively assessed with the different critical rainfall intensity. They provide a new insight into the spatial distribution and characteristics of postearthquake rainfall-triggered landslides in the Lushan seismic area. An increase of rainfall intensity results in a significant increase of unstable area. The heterogeneous distribution of slope instability is strongly correlated with the distribution of earthquake intensity in spite of different rainfall conditions. The results suggest that the both seismic intensity and rainfall are two crucial factors for postearthquake slope stability. This study provides important references for landslide prevention and mitigation in the Lushan area after earthquake.

An hourly shallow landslide warning model developed by combining automatic landslide spatial susceptibility and temporal rainfall threshold predictions

Landslide warning models are important for mitigating landslide risks.The rainfall threshold model is the most widely used early warning model for predicting rainfall-triggered landslides.Recently,the rainfall threshold model has been coupled with the landslide susceptibility(LS)model to improve the accuracy of early warnings in the spatial domain.Existing coupled models,designed based on a matrix including predefined rainfall thresholds and susceptibility levels,have been used to determine the warning level.These predefined classifications inevitably have subjective rainfall thresholds and susceptibility levels,thus affecting the probability distribution information and eventually influencing the reliability of the produced early warning.In this paper,we propose a novel landslide warning model in which the temporal and spatial probabilities of landslides are coupled without predefining the classified levels.The temporal probability of landslides is obtained from the probability distribution of rainfall intensities that triggered historical landslides.The spatial probability of landslides is then obtained from the susceptibility probability distribution.A case study shows that the proposed probability-coupled model can successfully provide hourly warning results before the occurrence of a landslide.Although all three models successfully predicted the landslide,the probability-coupled model produced a warning zone comprising the fewest grid cells.Quantitatively,the probabilitycoupled model produced only 39 grid cells in the warning zone,while the rainfall threshold model and the matrix-coupled model produced warning zones including 81 and 49 grid cells,respectively.The proposed model is also applicable to other regions affected by rainfall-induced landslides and is thus expected to be useful for practical landslide risk management.

穴位注射联合药物治疗急性带状疱疹临床观察

目的观察丹参注射液夹脊穴注射联合口服药物预防老年急性带状疱疹后遗神经痛(PHN)的临床疗效。方法带状疱疹患者100例,随机分为治疗组和对照组,每组50例。对照组给予口服盐酸伐昔洛韦片、加巴喷丁治疗,治疗组在对照组治疗的基础上给予丹参注射液夹脊穴注射治疗。两组患者必要时给予口服曲马多缓释片。观察两组治疗前和治疗后1周、3周、6周、12周和24周视觉模拟量表(VAS)评分及每周口服药物总量。记录治疗后12周、24周PHN发生情况。采用SF-36健康量表(SF-36)分别记录治疗前后12周和24周SF-36评分。观察头晕、嗜睡、恶心不良反应发生情况。结果治疗后1周、3周、6周、12周和24周,两组VAS评分明显低于治疗前(P<0.01),治疗组VAS评分明显低于对照组(P<0.01)。治疗后3、6、12和24周治疗组每周口服加巴喷丁剂量和曲马多缓释片剂量明显低于对照组(P<0.05)。治疗组治疗后12周和24周PHN发生率明显低于对照组(P<0.05)。治疗后12周和24周,治疗组SF-36中RF、RP、BP、VT和MH评分明显高于对照组(P<0.05)。治疗组头晕、嗜睡、恶心发生率明显低于对照组(P<0.05)。结论丹参注射液夹脊穴注射联合口服药物能有效降低急性带状疱疹相关性疼痛,可能是预防PHN的一种可行性方法。

间充质干细胞治疗椎间盘退行性变的研究进展

椎间盘退行性变(IDD)是引起下腰痛的主要病因之一[1],IDD导致的椎间隙狭窄是下腰痛重要发病机制[2-3]。成人椎间盘是人体最大的无血管组织且细胞含量较少[4]。IDD不同于正常衰老,衰老属于生理现象,不引起疼痛,而IDD则会引起髓核细胞(NPC)活性下降、数量减少,椎间隙高度丢失等,从而产生下腰痛。IDD的非手术治疗[5]和手术治疗[6]对短期疼痛缓解有一定的效果,但疼痛复发率较高,手术治疗甚至会加快同一节段或相邻节段椎间盘的退行性变,且均不能从根本上中止或者逆转IDD的发病进程。因此,探索从分子生物学方面阻止甚至逆转IDD的发展进程具有重要的临床意义。近年来,干细胞治疗技术的飞速发展为从根本上治疗IDD带来希望,本文对应用广泛的间充质干细胞(MSCs)治疗IDD的相关研究进行分析,现综述如下。

穴位注射配合药物治疗带状疱疹后遗神经痛的临床研究

目的观察穴位注射配合药物治疗带状疱疹后遗神经痛的临床疗效。方法将64例带状疱疹后遗神经痛患者随机分为治疗组和对照组,每组32例。治疗组采用夹脊穴注射丹参注射液配合口服加巴喷丁片治疗,对照组采用单纯口服加巴喷丁片治疗。两组如疼痛严重可加服盐酸曲马多缓释片治疗。观察两组治疗前后视觉模拟评分法(visual analogue scale, VAS)评分、SF-36健康量表(the MOS 36-item short-form health survey,SF-36)各项评分的变化情况,并比较两组不同时间点服用加巴喷丁片和盐酸曲马多缓释片的剂量及各项不良反应的发生率。结果两组治疗后不同时间点(治疗1周、3周、6周、12周、24周后)VAS评分与同组治疗前比较,差异均有统计学意义(P<0.01)。治疗组治疗后不同时间点VAS评分与对照组比较,差异具有统计学意义(P<0.01)。两组治疗3周、6周、12周、24周后加巴喷丁片和盐酸曲马多缓释片的服用剂量比较,差异均具有统计学意义(P<0.05)。两组治疗12周、24周后SF-36各项评分(PF、RP、BP、GH、VT、SF、RE、MH)与同组治疗前比较,差异均具有统计学意义(P<0.05)。治疗组治疗12周、24周后SF-36中PF、RP、BP、VT、MH评分与对照组比较,差异均具有统计学意义(P<0.05)。治疗组治疗后头晕、嗜睡、恶心的发生率分别为6.7%、3.3%和3.3%,对照组分别为24.1%、17.2%和20.7%,两组比较差异均具有统计学意义(P<0.05)。结论穴位注射配合药物是一种治疗带状疱疹后遗神经痛的有效方法,能减少服用加巴喷丁片的剂量,从而减少不良反应。

梅花井煤矿EBZ-200型掘进机掘锚一体化的应用

介绍了梅花井煤矿将EBZ-200型掘进机改造后实现一台机器截割和顶帮支护同时作业,在实现掘进和锚护平行作业方面优势显著。从掘锚一体化作业的截割方式、锚护方式、作业状态三方面入手,阐述分析了其在井下现场应用中的优势和不足,并做出改进和探索,为传统式的悬臂式掘进机升级改造开辟出一条宝贵的经验之路。