Insect pupil mechanisms

Summary The spectral characteristics of the pupil mechanism in blowfly photoreceptors and their dependence on light intensity have been investigated together with the intensity dependence of the receptor potential. The threshold for the pupil response as measured by reflectance is found at an intensity at which the peak of the receptor potential is about half maximal and the plateau potential starts to saturate. The reflectance saturates at about 3 log-units above threshold. The reflectance spectrum peaks near 620 nm, and its shape is independent of adaptation intensity. The absorbance change, measured by transmission, is extreme in the blue, at about 470 nm. The shape of the absorbance spectrum is slightly intensity dependent, presumably due to optical waveguide effects. The dynamic ranges of the light-induced reflectance and absorbance changes do not coincide. The reflectance change shows saturation at least 1 to 1.5 log units before the absorbance change saturates.     

超声联合钼靶X线对直径小于1 cm的乳腺癌诊断价值分析

目的:探讨超声联合钼靶X线对直径小于1 cm的乳腺癌诊断价值。方法:选择我院2012年1月至2017年12月收治的66例乳腺疾病患者,所有患者术前均经钼靶X线及彩色多普勒超声检查,分析其病理结果,分析钼靶X线、彩色多普勒超声及二者联合对乳腺肿块的检查结果(边缘毛刺征、血管、淋巴结、微小钙化),比较其对乳腺癌的灵敏度、特异度、准确度、阳性预测值及阴性预测值。结果:66例患者中,经病理检查发现恶性肿瘤34例,良性肿瘤32例。与病理检测相比,彩色多普勒超声联合钼靶X线对乳腺肿块的良恶性检出率无差异性(P0.05),而彩色多普勒超声,钼靶X线的良恶性检出率均显著降低(P0.05)。彩色多普勒超声与钼靶X线良恶性检出率对比无差异(P0.05),但均低于彩色多普勒超声联合钼靶X线的检出率(P0.05)。彩色多普勒超声与钼靶X线对乳腺癌的边缘毛刺征的检出率对比无统计学意义(P0.05);彩色多普勒超声对血管和淋巴结的检出率明显高于钼靶X线,而微小钙化的检出率明显低于钼靶X线,对比差异有统计学意义(P0.05)。彩色多普勒超声联合钼靶X线的灵敏度、特异度、准确度、阳性预测值及阴性预测值均明显高于彩色多普勒超声及钼靶X线(P0.05),钼靶X线及彩色多普勒超声间对比无统计学意义(P0.05)。结论:彩色多普勒超声与钼靶X线对直径小于1 cm乳腺癌的诊断各有优势,二者联合应用的诊断价值优于单一诊断方法。     

宝石能谱CT评估冠状动脉介入治疗术后支架内成像质量的研究

目的:探讨宝石能谱CT用于冠状动脉支架内成像质量评估的应用价值。方法:回顾分析56例冠状动脉支架植入后患者,按照支架厚度及直径分成四组。采用宝石能谱CT对冠状动脉成像及同时进行冠状动脉造影患者的影像学资料,通过分析宝石能谱CT的冠状动脉的成像质量,与冠状动脉造影进行对比,得出宝石能谱CT用于冠状动脉介入治疗术后支架内成像质量评估的价值。结果:宝石能谱CT显示支架内再狭窄的敏感度为100%,特异度为98.6%,阴性预测值为100%。直径≥3 mm的支架内成像质量优于直径3 mm的支架。但支架直径和厚度对宝石能谱CT支架内成像质量的可评估率没有差异。结论:宝石能谱CT均能提供优秀的冠状动脉支架内成像质量,采用宝石能谱CT替代冠状动脉造影术可对冠脉支架术后支架内影像进行评估。     

Adaptive neuro-fuzzy inference system: Estimation of soil aggregates stability

In present study, the capabilities of multiple linear regression (MLR) and adaptive neuro-fuzzy inference system (ANFIS) in developing pedotransfer functions (PTFs) for estimating geometric mean diameter (GMD) and mean weight diameter (MWD), from routine soil properties and combination of routine soil properties and fractal dimension of aggregates were evaluated. For this reason 101 samples were collected form the Northwest of Iran and some their properties such as soil texture, pH, cation exchange capacity (CEC), and organic matter (OM), fractal dimension of aggregates between number-diameter (Dn), mass-diameter (Dmt), and bulk density-diameter (Dmy) were determined and used as an input variables for determining of mean weight diameter (MWD) and geometric mean diameter (GMD) by MLR and ANFIS PTFs. Results showed that the application of fractal dimension of aggregates as a predictor in two methods improved the accuracy of PTFs. As well as, results showed that ANFIS have greater potential for determination of the relationships between soil aggregate stability indices and other soil properties in compared with MLR. Therefore using of adaptive neuro-fuzzy inference system (ANFIS) in developing pedotransfer functions is recommended.     

喀斯特峰丛洼地原生林群落更新动态

基于木论国家级自然保护区内一个2 hm~2动态监测样地2007、2012和2017年3次植被调查数据,从物种组成、群落结构、重要值、多样性、死亡率、补员率等方面分析喀斯特峰丛洼地原生林群落动态特征。结果表明:2017年样地内木本植物包含46科95属123种,较2007增加2科,减少5属7种;较2012年增加2科,减少4属4种。10年来,该样地优势种变化不明显,重要值≥1的物种数在2017年减少了3种;但排名前5位的物种保持不变,只有个别物种的重要值排序发生了较大的变化。平均胸径、树高、生物量随时间推移而增加;第一个5年,平均胸径和树高差异不显著,但10年间差异显著。随着时间推移,Shannon-wiener指数逐渐减少,Simpson指数和Pielou指数逐渐增加。该森林群落总径级结构呈倒"J"形,总体上群落更新状态良好。10年间DBH≥1.0 cm个体的年死亡率为8.23%,年补员率为5.73%。群落中野桐(Mallotus japonicas)和枫香树(Liquidambar formosana)呈增长趋势,优势地位逐渐上升。20个物种中有约35%的物种更新不足,表现出衰退的迹象,导致群落的物种成分和结构出现较大的变化。群落内主要树种的更新和植被结构变化的分析对于预测森林未来的变化趋势具有重要意义。     

黄土丘陵区辽东栎和刺槐树干液流时滞效应与蒸腾特征的关联性

运用Granier热扩散探针法,于2016年7-9月对半干旱黄土丘陵区天然次生林树种辽东栎和人工林树种刺槐的树干液流进行连续测定,并同步监测气象因子和土壤含水量,用错位相关法分析液流通量密度与空气水汽压亏缺日变化的时滞长度,研究2个树种不同径级个体在不同土壤水分条件下液流通量密度与蒸腾驱动因子之间的时滞效应.结果表明:辽东栎和刺槐液流通量密度的日变化节律与气象因子显著相关,空气水汽压亏缺峰值的出现较辽东栎树干液流通量密度滞后118.2 min,较刺槐树干液流通量密度滞后39.5 min;而光合有效辐射的峰值通常滞后于辽东栎12.4 min,提前于刺槐68.5 min.液流通量密度和空气水汽压亏缺的时滞长度与树种和土壤含水量显著相关,辽东栎、刺槐在土壤含水量较高时段的时滞长度分别大于土壤含水量较低时段32.2和68.2 min.时滞长度与径级的相关性整体上未达到显著水平,但在土壤含水量较低时段小径级刺槐的时滞长度大于大径级21.4 min,差异达到了显著水平.两树种液流通量密度与空气水汽压亏缺之间的时滞效应反映了对蒸腾驱动因子的敏感性,较好的土壤水分条件有利于液流通量密度提早达到峰值,较低土壤水分会导致树干液流对气象环境因子响应的敏感性降低;刺槐树干液流受土壤水分的影响更显著.