网络传播中的“链接特性”对传播力的影响——以主持人的传播力为例

主持人作为一种传播主体,在传统媒体时代显现出一种专制的色彩,很容易发挥传播效力。在新媒体时代,每个人都拥有发言权,主持人若想保持其原有的传播效力,就必须深入了解互联网的链接特性,从运用帕累托定律、偏好链接等方面扩大主持人传播力。但是,主持人"链接"特性的稳定性与脆弱性并存,我们需要通过牢固树立枢纽节点的党性觉悟和提高各层级的媒介素养规避主持人链接特性的险性面。

Seismological method for prediction of areal rockbursts in deep mine with seismic source mechanism and unstable failure theory

The research on the rock burst prediction was made on the basis of seismology,rock mechanics and the data from Dongguashan Copper Mine(DCM) ,the deepest metal mine in China.The seismic responses to mining in DCM were investigated through the analyses of the spatio-temporal distribution of hypocenters,apparent stress and displacement of seismic events,and the process of the generation of hazardous seismicity in DCM was studied in the framework of the theory of asperity in the seismic source mechanism.A method of locating areas with hazardous seismicity and a conceptual model of hazardous seismic nucleation in DCM were proposed.A criterion of rockburst prediction was analyzed theoretically in the framework of unstable failure theories,and consequently,the rate of change in the ratio of the seismic stiffness of rock in a seismic nucleation area to that in surrounding area,dS/dt,is defined as an index of the rockburst prediction.The possibility of a rockburst will increase if dS/dt>0,and the possibility of rock burst will decrease if dS/dt<0.The correctness of these methods is demonstrated by analyses of rock failure cases in DCM.

Safety Aspects of Sustainable Storage Dams and Earthquake Safety of Existing Dams

The basic element in any sustainable dam project is safety, which includes the following safety elements： O structural safety, dam safety monitoring, operational safety and maintenance, and emergency planning. Long-term safety primarily includes the analysis of all hazards affecting the project; that is, hazards from the natural environment, hazards from the man-made environment, and project-specific and site-specific hazards. The special features of the seismic safety of dams are discussed. Large dams were the first structures to be systematically designed against earthquakes, starting in the 1930s. How- ever, the seismic safety of older dams is unknown, as most were designed using seismic design criteria and methods of dynamic analysis that are considered obsolete today. Therefore, we need to reevaluate the seismic safety of existing dams based on current state-of-the-art practices and rehabilitate deficient dams. For large dams, a site-specific seismic hazard analysis is usually recommended. Today, large dams and the safety-relevant elements used for controlling the reservoir after a strong earthquake must be able to withstand the ground motions of a safety evaluation earthquake. The ground motion parameters can be determined either by a probabilistic or a deterministic seismic hazard analysis. During strong earthquakes, inelastic deformations may occur in a dam; therefore, the seismic analysis has to be car- ried out in the time domain. Furthermore, earthquakes create multiple seismic hazards for dams such as ground shaking, fault movements, mass movements, and others. The ground motions needed by the dam engineer are not real earthquake ground motions but models of the ground motion, which allow the safe design of dams. It must also be kept in mind that darn safety evaluations must be carried out several times during the long life of large storage dams. These features are discussed in this paper.

Application of Dangerous Probability Function in Risk Estimation of Surface Rupture Earthquake: Taking the Lingwu Fault in Ningxia Region as an Example

Based on the fitting on paleoearthquake data of intra-plate regions in the northern part of China and giving a statistical model of time interdependence, the potential damage earthquakes in a definite future period and characteristics of present shocks along the Lingwu fault have been analyzed by using dangerous probability function and some new data concerned. We have inferred that the fault has entered a period that earthquakes will probably occur. There exists a potential danger that a strong earthquake with M\-S7.0～7.5 will occur in 10～100a.

A poor performance in comprehensive geriatric assessment is associated with increased fall risk in elders with hypertension： a cross-sectional study

Background Fall and serious fall injuries have become a major health concern for elders. Many factors including blood pressure and anti-hypertensive medication application were reported as hazards of fall. The purpose of this study was to determine if age related systemic functional decline related with increased fall risks in elderly patients with hypertension. Methods A total of 342 elderly hypertension patients （age 79.5 ＋ 6.7 years, male 63.8%） were recruited to the study. Comprehensive geriatric assessment （CGA）, including measurements about activity of daily living （ADL）, nutrition, cognition, depression, numbers of prescription medication and number of clinical diagnosis, was conducted to evaluate the physical and mental status of each participants. Fall risk was evaluated by Morse fall scale, Tinetti perform- ance oriented mobility assessment （POMA） and history of fall in the recent years. Participants were grouped into tertiles according to CGA score. Correlation between CGA and fall risk was analyzed through SPSS 18.0. Results Participants with higher CGA score were likely to be older, had a lower body mass index （BMI）, and a higher prevalence of cardiovascular disease, chronic obstructive pulmonary disease （COPD）, cerebrovascular disease and osteoarthropathia. Participants in higher tertile of CGA score got increased prevalence of fall risk than those in lower tertile （P 〈 0.01 T3 vs. T1, P 〈 0.01 T3 vs. T2）. Correlation analysis and regression analysis showed significant association between CGA and Morse fall scale （P 〈 0.001）, as well as CGA and POMA （P 〈 0.001）. Meanwhile, CGA components also showed co-relationships with increase fall risks. After adjusting age, BMI, benzodiazepine use, cardiovascular disease, cerebrovascular disease, COPD and osteoarthropathia, both history of fall in the recent year and rising Morse fall scale were significantly associated with ADL im- pairment （OR： 2.748, 95%CI： 1.598-4.725）, （OR： 3.310, 95%CI： 1.893-5.788）. Decreased Tinetti POMA score was associated with Mini-Mental State Examination （MMSE） （OR： 4.035, 95%CI： 2.100-7.751）, ADL （OR： 2.380, 95%CI： 1.357-4.175） and shortened MNA form （MNA-SF） impairment （OR： 2.692, 95%CI： 1.147-6.319）. Conclusions In elderly adults with hypertension, impaired physical and mental function is associated with increased fall risk. Further study is required to investigate possible mediators for the association and effec- tive interventions.

Genotyping and Antifungal Susceptibility Profile of Sequential Candida albicans Isolated from the Oral Cavity of HIV-Infected Individuals

Objective： The study aimed to evaluate the genotypic profiles of C. albicans （Candida albicans） sequentially isolated throughout the course of HIV infections, and to determine its MIC （minimal inhibitory concentrations） to AMB （amphotericin B）, FLC （fluconazole）, KTC （ketoconazole）, and ITC （itraconazole）. Design： samples were collected from the oral cavity of HIV-positive individuals during 4 years, with a sterilized swab. MIC was performed by using the microdilution method AFST/EUCAST. The genetic similarities within and between sequential clones of C. albicans were assessed by DNA fingerprinting using the random amplification ofpolymorphic DNA technique. Results： A total of 142 oral samples were isolated from 59 HIV-infected individuals who attempted up to five visits each, with or without symptoms of oropharyngeal candidiasis. Profile analysis revealed that yeasts isolated over sequential visits from symptomatic or asymptomatic individuals showed 78% or 87% relatedness, respectively. The degree of similarity among C. albicans was higher for isolates from colonization than for those from infection. Genetically identical C. albicans samples also formed connected subelusters in sequential visits. In regard to susceptibility profile, all isolates were susceptible to AMB, FLC, KTC, and ITC and maintained this pattern all along, no differences in MICs of any given antifungal compound were observed for sequential C. albicans isolates. Conclusions： These data suggest that genotype and susceptibility to antifimgal drugs were maintained over time in sequentially isolates of C. albicans colonization and a diverse evolutionary genetic trend in C. albicans sequentially isolated from the oral eandidiasis of HIV infected individuals.

Seismic Hazard Assessment for Japan after the 2011 Tohoku-Oki Mega-Thrust Earthquake （Mw9.0）

The Tohoku-Oki earthquake （Mw 9.0） of March 11,2011, was the largest event in the history of Japan. This magnitude 9.0 mega-thrust earthquake initiated approximately 100 km off-shore of Miyagi prefecture and the rupture extended 400-500 km along the Pacific plate. Due to the strong ground motions and tsunami associated by this event, approximately twenty thousand people were killed or missing and more than 220 thousands houses and buildings were totally or partially destroyed. This mega-thrust earthquake was not considered in the national seismic hazard maps for Japan that was published by the HERP （headquarters for earthquake research promotion） of Japan. By comparing the results of the seismic hazard assessment and observed strong ground motions, we understand that the results of assessment were underestimated in Fukushima prefecture and northern part of Ibaraki prefecture. Its cause primarily lies in that it failed to evaluate the Mw 9.0 mega-thrust earthquake in the long-term evaluation for seismic activities. On the other hand, another cause is that we could not make the functional framework which is prepared for treatment of uncertainty for probabilistic seismic hazard assessment work fully. Based on the lessons learned from this earthquake disaster and the experience that we have engaged in the seismic hazard mapping project of Japan, we consider problems and issues to be resolved for probabilistic seismic hazard assessment and make new proposals to improve probabilistic seismic hazard assessment for Japan.

Dynamic mechanisms of earthquake-triggered landslides

Earthquake-triggered landslides usually cause great disasters,and yet their dynamic mechanisms remain poorly understood.This paper will derive a general conceptual landslide model from the geometric and kinematic features of the most landslide masses triggered by the 2008 Wenchuan earthquake.Kinematic characteristics and dynamic processes are simulated here by means of finite element method(FEM)based on the dynamic process of the discontinuous deformable body.The calculated results presented the whole course of landslide motion,and displayed some typical kinematic characteristics such as initiation,sliding,ejection,collision,flying in the air,and climbing of landslides.The simulation result also shows that,under combined seismic inertial forces and gravity,landslides will start to slip once it overcomes the friction between the sliding mass and slip-bed,then it will move from slow to fast along the slippery bed until it ejects from the slip-bed.Moreover,the high frequencies and serious damages by landslides in the Wenchuan earthquake are caused by the strong ground motion on the mountain slopes in and around the epicenter that was dramatically amplified owing to both resonances produced by the seismic event and topographical amplification by seismic motion.In addition,the modeling results suggest that the direction,amplitude,frequency,and duration of strong ground motion have a great influence on the stability of landslide mass.Therefore,the study helps us better understand dynamic mechanism of landslides,seismic hazard assessment,and dynamic earthquake triggering.