Ultra-early amplitude decrement after repetitive nerve stimulation supports early neuromuscular junction injury in amyotrophic lateral sclerosis:a prospective cross-sectional study

The dying-back hypothesis holds that the damage to neuromuscular junctions and distal axons in amyotrophic lateral sclerosis occurs at the earliest stage of the disease.Previous basic studies have confirmed early damage to neuromuscular junctions,but it is difficult to obtain such evidence directly in clinical practice.In this prospective cross-sectional study,we recruited 22 patients with early amyotrophic lateral sclerosis with disease duration < 12 months and with clinical symptoms limited to the upper limbs.We also recruited 32 healthy controls.Repetitive nerve stimulation was performed,and patients were followed for 12 months.We found a significant change in the response to repetitive nerve stimulation in amyotrophic lateral sclerosis patients without spontaneous electromyographic activity.Patients that were prone to denervation had an increased decrement response of target muscles after repetitive nerve stimulation.These results suggest that changes in response to repetitive nerve stimulation may occur before denervation in amyotrophic lateral sclerosis patients.The damage to lower motor neurons is more obvious in patients with a higher percentage of repetitive never stimulation-related amplitude decrements.This study was approved by the Institutional Ethics Committee of Peking University Third Hospital(approval No.M2017198) on August 24,2017.

基于Vector Random Decrement技术和特征系统实现算法ERA的模态参数识别

现代的大型复杂结构,如大坝、高层建筑、桥梁及海洋平台等,处于复杂的环境载荷作用下,这些环境载荷往往是无法测量的。在仅有输出响应时,应用随机减量法RDT获得自由衰减响应信号,而后用时域复指数拟合法、ITD法、特征系统实现算法ERA等算法获得结构的模态参数是一种有效的方法。但在数据量有限时,随机减量函数的平均次数过少,导致RD函数的收敛性较差。为此提出了利用Vector Random Decrement技术(VRDT)提取自由衰减响应信号,而后利用特征系统实现算法ERA求得模态参数的方法,新算法能够有效地提高模态参数识别精度。数值算例验证了所提算法的有效性。

Effects of dielectric decrement on surface potential in a mixed electrolyte solution

Surface potential is an important parameter related to the physical and chemical properties of charged particles. A simple analytical model for the estimation of surface potential is established based on the Poisson–Boltzmann theory with the consideration of the dielectric decrement in mixed electrolyte. The analytical relationships between surface potential and charge density are derived in different mixed electrolytes with monovalent and bivalent ions. The dielectric decrease on the charged surface strongly affects the surface potential at a high charge density with different ion strengths and concentration ratios of counter-ions. The surface potential based on the Gouy–Chapman model is underestimated because of the dielectric decrement on the surface. The diffuse layer can be regarded as a continuous uniform medium only when the surface charge density is lower than 0.3 C·m-2. However, the surface charge densities of many materials in practical applications are higher than 0.3 C·m-2. The new model for the estimation of surface potential can return to the results obtained based on the Gouy–Chapman model at a low charge density. Therefore, it is implied that the established model that considers the dielectric decrement is valid and widely applicable.

DARM: Decremental Association Rules Mining

Frequent item sets mining plays an important role in association rules mining. A variety of algorithms for finding frequent item sets in very large transaction databases have been developed. Although many techniques were proposed for maintenance of the discovered rules when new transactions are added, little work is done for maintaining the discovered rules when some transactions are deleted from the database. Updates are fundamental aspect of data management. In this paper, a decremental association rules mining algorithm is present for updating the discovered association rules when some transactions are removed from the original data set. Extensive experiments were conducted to evaluate the performance of the proposed algorithm. The results show that the proposed algorithm is efficient and outperforms other well-known algorithms.

Electrophysiologic behaviour of a left sided accessory pathway with decremental (Mahaim-like) properties

The observation of a left sided accessory pathway with decremental properties is rare. We describe the behaviour of one of these pathways which was characterized by the presence of retrograde conduction (not previously reported) and thus inducibility of atrio-ventricular orthodromic reentrant tachycardia.

3种喷雾助剂对5%氯虫苯甲酰胺悬浮剂防治番茄潜叶蛾的增效作用

为评价喷雾助剂对5%氯虫苯甲酰胺悬浮剂防治番茄潜叶蛾Phthorimaea absoluta Meyrick的增效作用,分别向比推荐用量减量10%、20%、30%的药液中添加有机硅Silwet 408、矿物油或芦荟精油助剂至终浓度为0.05%(V/V),测定其对番茄潜叶蛾的田间防效。结果显示,添加3种喷雾助剂均能不同程度地提高5%氯虫苯甲酰胺悬浮剂对番茄潜叶蛾的防效。相较于推荐用量,添加有机硅Silwet 408、矿物油或芦荟精油可使农药减量10%~20%。田间应用时可将5%氯虫苯甲酰胺悬浮剂按照推荐用量减量10%~20%,并添加有机硅Silwet 408、矿物油或芦荟精油来防治番茄潜叶蛾。

海南荔枝养分投入限量标准及减量潜力分析

海南是我国荔枝最南端的生产区,但生产中养分过量投入和土壤退化的问题较为严重,缺乏合理的养分投入标准。本研究根据作物产量水平及当下优化管理获得氮素盈余关键阈值,解析不同类型农户养分管理水平的差异以及对土壤肥力的影响。通过对海南主产区荔枝产量、养分管理和土壤肥力现状进行剖析,基于养分平衡原理,通过定量作物养分需求规律及优化条件下的合理氮素盈余水平,明确荔枝养分用量上限,提出海南荔枝氮、磷、钾养分投入减量目标,对不同经营规模的农户养分收支平衡和土壤肥力差异开展评价。结果表明:(1)不同产量水平下荔枝氮、磷、钾用量上限分别为200、100、260 kg/hm^(2)(产量<10 t/hm^(2));273、136、355 kg/hm^(2)(产量为10~20 t/hm^(2));439、220、571 kg/hm^(2)(产量为20~42 t/hm^(2))。农户施肥过量投入现象较为突出,且随着经营规模的增加,养分过量投入加剧。小农户、中等经营主体、规模化经营主体氮素投入分别高于氮肥投入上限的60%、97%、131%;磷素投入量分别高于磷肥投入上限的204%、236%、258%;钾素投入量分别高于钾肥投入上限的70%、101%、119%。同时海南荔枝氮、磷、钾养分投入均显著高于全国荔枝施肥平均水平的70.8%、189.9%、123.4%。(2)海南荔枝园氮、磷、钾养分盈余分别为365、377、542 kg/hm^(2),养分利用效率(NUE)分别为34%、21%、27%,大量磷素在土壤中固定或损失。不同类型农户养分管理存在较大差异,只有1.2%的小农户处于高氮产出和低氮盈余区间,而中高经营主体均处于高氮素盈余水平区间。(3)荔枝果园土壤磷素过量积累和土壤酸化问题突出,46%的果园土壤全磷含量超过0.96 g/kg,处于较丰富水平。94%的果园为酸性土(pH4.5~5.5),77%的果园土壤质量指数(IFI)综合评级较低。针对目前海南荔枝养分投入不合理及土壤退化问题,应尽快采取和推广肥料定额制度,同时提高有机肥和化肥利用效率,推动荔枝产业的绿色发展。

渐进减量的腹膜透析患者临床特征分析

目的临床上观察到少量腹膜透析患者可实现足量起始,逐渐减量,并以小剂量(透析剂量≤4 L/d)维持透析,本研究分析该部分患者的临床特点,探讨渐进减量腹膜透析的可行性及安全性。方法筛选2012年1月—2018年12月于西安交通大学医学院第一附属医院腹膜透析中心置管并符合渐进减量至小剂量透析(以≤4 L/d维持6月以上)的患者,排除急性肾损伤、狼疮性肾炎、血管炎、梗阻性肾病患者。收集其基线肾功、尿量,计算基线(定义为透析1月时)、减量前(指减量至4 L/d前),小剂量维持6月后(指≤4 L/d维持6月时)残余肾功能、腹膜透析充分性。结果共19例患者纳入研究,平均年龄(49.87±20.53)岁,女性11例,男性8例,进入透析时的中位估算肾小球滤过率(estimating glomerular filtration rate,eGFR)为6.87(4.98,9.44)ml/(min·1.73m^(2))。慢性肾小球肾炎8例,糖尿病肾病、高血压肾损害、间质性肾炎各3例、IgA肾病/紫癜性肾炎2例。16例患者起始腹膜透析剂量为6 L/d,3例患者起始剂量为8 L/d。减为小剂量(≤4 L/d)的中位时间为5.33(4.57,14.20)透析月,小剂量维持的中位时间为22.17(13.13,45.80)月。基线时残余肾功能为(4.95±2.04)ml/min,减量前残余肾功能为(7.85±2.78)ml/min,较基线升高(F=10.284,P=0.005)。减量前尿量较基线增加(F=7.374,P=0.015)。小剂量透析维持6月后总尿素清除指数(tKt/V)、总肌酐清除率(total creatinine clearance,tCCr)较减量前无明显变化(F=3.436、0.015,P=0.082、0.904)。结论少量慢性肾衰竭患者经足量透析后残余肾功能较前改善,在该部分患者中小幅渐进减少透析剂量至小剂量维持的方法安全有效。

“絮凝脱水+高压带机+好氧发酵”组合工艺在粪便污泥处理中的应用

河北省某粪便处理站收集并处理附近学校产生的粪便污水,原采用“絮凝脱水+好氧发酵”工艺,将粪便污泥处理至含水率84%左右,然后进行好氧发酵堆肥。但是,含水率84%的粪便直接进行好氧发酵,必须添加大量辅料,存在堆肥物料易板结、氧气传质效率低、运行成本高等问题,影响堆肥产品质量。为提高粪便污泥好氧发酵效率,降低运行成本,在充分利用原有设备和场地的前提下,原脱水工艺后端和好氧发酵工艺前端增加高压带式深度脱水工艺。该项目连续运行结果表明,经高压带式深度脱水工艺处理后,粪便平均含水率从84%降至59%,粪便减量率达61%,节省辅料90%,改造后粪便减量效果和经济效益显著。

BALMER DECREMENT OF QUASARS AND SEYFERT I GALAXIES

We compile the observed intensity ratios of the Balmer lines for low redshift quasars and Seyfert Ⅰ galaxies. In the framework of the Cerenkov line emission theory, we compare the theoretical intensity ratios with those of observations, and find that the observed intensity ratios for the radio-loud quasars and the Seyfert Ⅰ galaxies are nearer to the theoretical expectation than those for the radio-quiet sources. It seems that for the radio-loud AGNs, the characteristics of the Cerenkov line emission are more remarkable because of the existence of a great number of relativistic electrons. We also discuss the reddening by dust in quasars and the Seyfert galaxies. The fact that the reddening of the Seyfert galaxies is more serious than quasars shows that the Seyfert galaxies have more dust than quasars. This is in agreement with the present point of view.

国内城镇污水处理污泥脱水技术研究进展

随着污泥成分日趋复杂、污泥量的不断增大,污泥的妥善处理和处置问题已成为我国诸多城镇日益迫切的环保难题。针对污泥含水率高,装卸运输和后续处置困难等问题,综述了国内污泥脱水减量方面常见技术和新近技术的研究进展,并提出相关建议。经济高效、低碳节能型污泥脱水技术与装备将是污泥处理领域的未来重点研究方向。

Strong Consistency and CLT for the Random Decrement Estimator

The random decrement technique （RDT）, introduced in the sixties by Cole [NASA CR- 2005, 1973], is a very performing method of analysis for vibration signature of a structure under ambient loading. But the real nature of the random decrement signature has been misunderstood until now. Moreover, the various interpretations were made in continuous time setting, while real experimental data are obtained in discrete time. In this paper, the really implemental discrete time algorithms are studied. The asymptotic analysis as the number of triggering points go to infinity is achieved, and a Law of Large Numbers as well as a Central Limit Theorem is proved. Moreover, the limit as the discretization time step goes to zero is computed, giving more tractable formulas to approximate the random decrement. This is a new approach of the famous ＂Kac-Slepian paradox＂ [Ann. Math. Star., 30, 1215-1228 （1959）]. The main point might be that the RDT is a very efficient functional estimator of the correlation function of a stationary ergodic Gaussian process. Very fast, it is to classical estimators what Fast Fourier Transform （FFT） is to ordinary Discrete Fourier Transforms.

Reflections and Explorations on the Decremented Regulation of Construction Land in the New Beijing City Master Planning

Construction land use has always been a key point for the planning department to practice national transformation strategy. In the new round of compilation of Beijing City Master Plan, the management of construction land use is under the rigid restriction of the bearing capacity of resources and the environment. Setting the upper-limit of the population size, a general strategy of decremented development of urban-rural construction land has been put forward, in order to realize a transition from quantitative expansion planning to qualitative upgrading planning. By "decremented development," "decremented" means a more rigid bottom-line restriction, and "development" means a more scientific allocation of resources. From the master planning level, the new Beijing City Master Plan establishes a comprehensive control framework and restrictive index system from perspectives including land use scale, construction scale, space boundary, urban and rural structure, land use structure, and cross-boundary collaboration; and in practice, it promotes strict management methods by setting up a dismantle-construction land ratio, dismantle-construction building area ratio, employment and residence land ratio, and "two lines and three districts," which is an exploration on the planning management method of construction land use that is stock-based and decremented master planning. Considering that decremented development is a major reform and a special challenge to planning implementation, the Beijing City Master Plan carries out explorations in terms of the planning management method, land policy, jurisdiction division, assessment and supervision, etc.

“层层加码”与“层层递减”:基层执行的策略选择及其组合

“层层加码”与“层层递减”是我国基层治理过程中存在的两种不同的政策执行状态,二者是我国复杂治理情境下多因素叠加作用的结果。对“层层加码”与“层层递减”的逻辑选择及生发机理展开探究,能够使我们从外在现象切入机理洞察深层次原因和动机。邀功与避责心态的驱使、为任务预留空间、政策模糊和属地管理构成了“层层加码”的策略选择;而权责分离、职业倦怠、形式主义等传统问题与“委托—代理”关系则是基层“层层递减”的生成逻辑;基层的适应性执行、内卷化执行则是在“加”与“减”间寻求平衡的全新策略。如何将“层层加码”与“层层递减”控制在合理限度内是现实中应予重点考虑的问题。

建筑外墙延迟衰减特性的组合优化方法

研究建筑外墙不同组合延迟衰减特性对建筑峰值传热的影响规律,对降低峰值传热负荷,减少空调系统配置容量具有重要意义.针对某案例建筑,采用EnergyPlus与正交试验设计方法,研究多类型建筑外墙组合延迟衰减特性与峰值传热冷负荷的变化规律.结果表明:各墙体组合对外扰具有不同的延迟衰减特性,导致峰值冷负荷大小存在显著差异,差异度最大为11.8%.基于不同类型建筑外墙传热峰值出现时刻不同,叠加后可降低总传热量峰值的特性,提出一种外墙峰值传热优化组合方法.在各朝向墙体内表面温度关系式中引入错峰指标PSI,用于调节墙体组合的延迟时间,以该指标为设计变量,墙体总传热量峰值为目标函数,通过优化求解得到各朝向墙体的最佳延迟时间,进而求出优化墙体组合.采用该方法对案例建筑进行计算,结果显示:对建筑外墙进行优化组合后,其总传热量峰值降低了19.1%.

Study of Construction Techniques and Hygro-Thermal Behavior of a Vernacular Earth Building in a Humid Tropical Climate

This study analyzes the know-how of local communities, to draw on techniques that make contemporary buildings more energy efficient. The impluvium hut in the locality of Enampore, Casamance, Southern Senegal, served as the object of study. The hut, including several rooms, is entirely built with earthen walls, earthen floor, earthen ceiling, covered by a double straw roof and its central courtyard. A room noted (L) and a semi-opened living space were chosen as spaces for hygro-thermal experimentation. The hottest average temperature obtained respectively in the room (L) and in the living space is 25.5˚C and 27˚C when outside is about 34˚C. The thermal amplitude inside room (L) is 0.88˚C, in semi-opened living space, is 2.6˚C and outside is 9.5˚C. With these results we can say that room (L) undergoes very low temperature variations and that there is no need to air-condition in the enclosure. The thermal amplitude makes it possible to see the influence of the earthen walls on the interior temperature and its regularity compared to the fluctuation of the external temperature. The thermal inertia of the building walls was characterized using also the time lag and the decrement factor. They was respectively 7.0 H and 0.093 for the room (L). With this result we can say that this material has a high thermal inertia. For humidity, it is high around 78.5% in the room (L), 66.0% at the semi-open living room, when it is 59.0% outside. Through this study, it is possible that the revalorization of vernacular architecture can be an alternative to reduce the energy consumption of buildings.

大豆病虫草害化学防治减量技术研究

近年来,受国家政策及市场调控影响,大豆价格高位运行,农户种植热情高涨,而病虫草害是制约大豆产量的主要因素。富锦市大豆栽培中,大豆根腐病、大豆蚜虫、大豆食叶性害虫、大豆灰斑病、大豆霜霉病、大豆食心虫等病虫害,以及刺菜、红根苋菜、鸭趾草等抗性杂草多发,科学合理地使用化学农药是防治大豆病虫害的重中之重。从种子处理、开花结荚病害防治、大豆食心虫防除、封闭加茎叶两次用药除草,综合防治大豆病虫草害进行技术研究,达到了绿色、减量、高效,增产增收,保护环境目的。

非蛋白氮在反刍动物生产中的研究进展

我国作为养殖大国,蛋白质饲料供不应求,急需寻求在动物生产中减量替代蛋白质饲料的方法。尿素等非蛋白氮价格低廉,在反刍动物生产中可以替代部分蛋白质饲料,为瘤胃微生物合成蛋白质提供氮源,进而降低生产成本。近年来,有关液体饲料的研究和应用日益增多,但其在反刍动物生产中的相关研究较少。文章总结了反刍动物利用非蛋白氮的原理及非蛋白氮在反刍动物生产中的应用情况,为反刍动物非蛋白氮液态精饲料的开发与利用提供参考。

畜禽饲料常用植物蛋白源理化性质比较研究

我国饲料原料种类繁多,多元化配方模式下不同原料理化性质差异对饲料制粒性能、生产效率和颗粒物理质量具有显著影响,但相关研究数据较为缺乏。研究以畜禽饲料中常用植物蛋白源:豆粕、棉籽粕、花生粕和菜籽粕为试验材料,检测分析不同蛋白原料粗蛋白质、粗脂肪、粗纤维、粗灰分等基本物质组成以及密度、流动性、吸水性、水溶性、黏度等理化特性,旨在为不同植物蛋白原料在畜禽饲料加工中的合理应用及工艺参数调整提供参考。结果表明:豆粕粗纤维及灰分含量最低,密度大且流动性好,水溶性指数和水溶性蛋白含量高,与面粉混合后黏度大、淀粉糊化温度低。棉籽粕粗蛋白质和粗纤维含量较高,水溶性差,与面粉混合后黏度低、淀粉糊化温度较高。花生粕粗脂肪、粗纤维及水分含量低,吸水性最强且与面粉混合后黏度较高。菜籽粕粗蛋白质含量最低,粗纤维及灰分含量最高,密度最低且流动性差,吸水性最差且水溶性蛋白含量低,与面粉混合后黏度低、淀粉糊化温度最高。综上所述,不同植物性蛋白原料物质组成及理化加工特性存在显著差异,在饲料加工中应综合考虑其对加工过程及饲料物理质量的影响,合理调整工艺参数以保证生产效率及产品质量稳定。

基于遗传算法与随机减量技术的气动阻尼识别方法研究

随机减量技术(random decrement technique,RDT)因其计算快、成本低的优点,在工程结构模态参数识别中应用广泛。针对RDT在信号截断幅值与样本时长的选取比较主观带来的误差问题,采用遗传算法(genetic algorithm,GA)对其进行改进,提出改进的随机减量技术GA-RDT,并将其应用于某超高层建筑气弹模型的气动阻尼识别。首先,对RDT方法得到的自由衰减曲线进行拟合并定义误差,分析截断幅值A和样本时长T对误差(优化目标)的影响,采用遗传算法寻找A和T的最优解;其次,基于气弹模型风洞试验所得的顶点加速度时程,结合GA-RDT方法和Hilbert-Huang变换(Hilbert-Huang transform,HHT)方法进行气动阻尼识别;最后,以自然激励技术(natural excitation technique,NExT)识别所得的气动阻尼比为基准,对比分析GA-RDT方法相对于传统RDT方法的精度优势。结果表明,与NExT方法所得的气动阻尼比相比,GA-RDT方法识别得到不同风速时X向、Y向与扭转向的气动阻尼比的平均误差均小于0.14%,其识别精度显著高于传统RDT方法,从而验证了基于GA-RDT的气动阻尼识别方法的可行性。