地震反射界面形态与介质各向异性属性联立成像：地震反射波旅行时与偏振信息综合反演

It has been a difficult problem faced by seismologists for long time that how exactly to reconstruct the earth's geometric structure and distribution of physical attributes according to seismic wave's kinematical and dynamic characteristics, obtained in seismological observation. The jointing imaging of seismic reflector and anisotropy attributes in the earth interior is becoming the research hot spot. The limitation of shoot and observation system makes that the obtained seismic data are too scarce to exactly reconstruct the geological objects. It is popular that utilizing only seismic reflection traveltimes or polarizations information make inversion of the earth's velocity distribution by fixing seismic reflector configuration (vice versa), these will lead to the serious non-uniqueness reconstruction due to short of effective data, the non-uniqueness problem of reconstructing anisotropy attributes will be more serious than in isotropy media. Obviously it is not enough to restrict the media structure only by information of seismic reflection traveltimes or polarizations, which even sometimes will lead to distorted images and misinterpretation of subsurface structure. So we try to rebuild seismic reflection structure (geometry) and media anisotropic structure (physics) in the earth interior by jointing data of seismic wave kinematics and dynamics characteristics, we carry out the new experiment step by step, and the research mainly comprises of two parts: one is the reconstruction of P-wave vertical velocity and anisotropic structure(Thomsen parameter s and 8) in the transversely isotropic media with vertical symmetrical axis(VTI) by fixing geometrical structure, and the other is the simultaneous inversion of the reflector surface conformation and seismic anisotropic structure by jointing seismic reflection traveltimes and polarizations data. Simulated annealing method is used to the first research part, linear inversion based on BG theory and Simulated annealing are applied to the second one. All the research methods are checked by model experiments, then applied to the real data of the wide-angle seismic profile from Tunxi, Anhui Province, to Wenzhou, Zhejiang Province. The results are as following The inversion results based on jointing seismic PP-wave or PSV-wavereflection traveltimes and polarizations data are more close to real model than themodels based simply on one of the two data respectively. It is shown that the methodwe present here can effectively reconstruct the anisotropy attributes in the earth'sinterior when seismic reflector structure is fixed.The layer thickness, P-wave vertical velocity and Thomsen anisotropicparameters {s and 8) could be resolved simultaneously by jointing inversion ofseismic reflection traveltimes and polarizations with the linear inversion methodbased on BG theory.The image of the reflector structure, P-wave vertical velocity and theanisotropy parameters in the crust could be obtained from the wide-angle seismicprofile from Tunxi (in Anhui Province), to Wenzhou (in Zhejiang Province). Theresults reveal the difference of the reflector geometrical structure and physicalattributes in the crust between Yangtze block and Cathaysia block, and attempt tounderstand the characteristics of the crustal stress field in the areas.

三峡库区滑坡的时空分布、成因及其预报模式

Landslides are widely distributed along the main stream banks of the Three Gorges Reservoir area. Especially with the acceleration of the human economic activities in the recent 30 years, the occurrence of landslide hazards in the local area trends to be more serious. Because of the special geological, topographic and climatic conditions of the Three Gorges areas, many Paleo-landslides are found along the gentle slope terrain of the population relocation sites. Under the natural condition, the Paleo-landslides usually keep stable. The Paleo-landslides might revive while they are influenced under the strong rainfall, water storage and migration engineering disturbance. Therefore, the prediction and prevention of landslide hazards have become the important problem involving with the safety of migration engineering of the Three Gorges Reservoir area.The past research on the landslides of the Three Gorges area is mainly concentrated on the stability analysis of individual landslide, and importance was little attached to the knowledge on the geological environment background of the formation of regional landslides. So, the relationship between distribution and evolution of landslides and globe dynamic processes was very scarce in the past research. With further study, it becomes difficult to explain the reasons for the magnitude and frequency of major geological hazards in terms of single endogenic or exogenic processes. It is possible to resolve the causes of major landslides in the Three Gorges area through the systematic research of regional tectonics and river evolution history.In present paper, based on the view of coupling of earth's endogenic and exogenic processes, the author researches the temporal and spacial distribution and formation evolution of major landslides(Volume^lOOX 104m3) in the Three Gorges Reservoir area through integration of first-hand sources statistics, .geological evolution history, isotope dating and numerical simulation method etc. And considering the main formation factors of landslides (topography, geology and rainfall condition), the author discusses the occurrence probability and prediction model of rainfall induced landslides.The distribution and magnitude of Paleo-landslides in the Three Gorges area is mainly controlled by lithology, geological structure, bank slope shape and geostress field etc. The major Paleo-landslides are concentrated on the periods 2.7-15.0 X 104aB.R, which conrresponds to the warm and wettest Paleoclimate stages. In the same time, the Three Gorges area experiences with the quickest crust uplift phase since 15.0X 104aB.P. It is indicated that the dynamic factor of polyphase major Paleo-landslides is the coupling processes of neotectonic movement and Quaternary climate changes. Based on the numerical simulation results of the formation evolution of Baota landslide, the quick crust uplift makes the deep river incision and the geostress relief causes the rock body of banks flexible. Under the strong rainfall condition, the pore-water pressure resulted from rain penetration and high flood level can have the shear strength of weak structural plane decrease to a great degree. Therefore, the bank slope is easy to slide at the slope bottom where shear stress concentrates. Finally, it forms the composite draught-traction type landslide of dip stratified rocks.The susceptibility idea for the rainfall induced landslide is put forward in this paper and the degree of susceptibility is graded in terms of the topography and geological conditions of landslides. Base on the integration with geological environment factors and rainfall condition, the author gives a new probabilistic prediction model for rainfall induced landslides. As an example from Chongqing City of the Three Gorges area, selecting the 5 factors of topography, lithology combination, slope shape, rock structure and hydrogeology and 21 kinds of status as prediction variables, the susceptibility zonation is carried out by information methods. The prediction criterion of landslides is established by two factors: the maximum 24 hour rainfall and the antecedent effective precipitation of 15 days. The new prediction model is possible to actualize the real-time regional landslide prediction and improve accuracy of landslide forecast.

Semi-Supervised OWA Aggregation for Link-Based Similarity Evaluation and Alias Detection

T.Boongoen and Q. Shen. Semi-Supervised OWA Aggregation for Link-Based Similarity Evaluation and Alias Detection. Proceedings of the 18th International Conference on Fuzzy Systems (FUZZ-IEEE'09), pp. 288-293, 2009. Sponsorship: EPSRC

Biological rationale for regular physical exercise as an effective intervention for the prevention and treatment of depressive disorders

Depression is a major medical and social problem. Here we review current body of knowledge on the benefits of exercise as an effective strategy for both the prevention and treatment of this condition. We also analyze the biological pathways involved in such potential benefits, which include changes in neurotrophic factors, oxidative stress and inflammation, telomere length, brain volume and microvessels, neurotransmitters or hormones. We also identify major caveats in this field of research: further studies are needed to identify which are the most appropriate types of exercise interventions (intensity, duration, or frequency) to treat and prevent depression.

The effect of hydrogen bonding on the diffusion of water in n-alkanes and n-alcohols measured with a novel single microdroplet method.

While the Stokes-Einstein (SE) equation predicts that the diffusion coefficient of a solute will be inversely proportional to the viscosity of the solvent, this relation is commonly known to fail for solutes, which are the same size or smaller than the solvent. Multiple researchers have reported that for small solutes, the diffusion coefficient is inversely proportional to the viscosity to a fractional power, and that solutes actually diffuse faster than SE predicts. For other solvent systems, attractive solute-solvent interactions, such as hydrogen bonding, are known to retard the diffusion of a solute. Some researchers have interpreted the slower diffusion due to hydrogen bonding as resulting from the effective diffusion of a larger complex of a solute and solvent molecules. We have developed and used a novel micropipette technique, which can form and hold a single microdroplet of water while it dissolves in a diffusion controlled environment into the solvent. This method has been used to examine the diffusion of water in both n-alkanes and n-alcohols. It was found that the polar solute water, diffusing in a solvent with which it cannot hydrogen bond, closely resembles small nonpolar solutes such as xenon and krypton diffusing in n-alkanes, with diffusion coefficients ranging from 12.5x10(-5) cm(2)/s for water in n-pentane to 1.15x10(-5) cm(2)/s for water in hexadecane. Diffusion coefficients were found to be inversely proportional to viscosity to a fractional power, and diffusion coefficients were faster than SE predicts. For water diffusing in a solvent (n-alcohols) with which it can hydrogen bond, diffusion coefficient values ranged from 1.75x10(-5) cm(2)/s in n-methanol to 0.364x10(-5) cm(2)/s in n-octanol, and diffusion was slower than an alkane of corresponding viscosity. We find no evidence for solute-solvent complex diffusion. Rather, it is possible that the small solute water may be retarded by relatively longer residence times (compared to non-H-bonding solvents) as it moves through the liquid.

Functional neuroimaging of emotionally intense autobiographical memories in post-traumatic stress disorder.

Post-traumatic stress disorder (PTSD) affects regions that support autobiographical memory (AM) retrieval, such as the hippocampus, amygdala and ventral medial prefrontal cortex (PFC). However, it is not well understood how PTSD may impact the neural mechanisms of memory retrieval for the personal past. We used a generic cue method combined with parametric modulation analysis and functional MRI (fMRI) to investigate the neural mechanisms affected by PTSD symptoms during the retrieval of a large sample of emotionally intense AMs. There were three main results. First, the PTSD group showed greater recruitment of the amygdala/hippocampus during the construction of negative versus positive emotionally intense AMs, when compared to controls. Second, across both the construction and elaboration phases of retrieval the PTSD group showed greater recruitment of the ventral medial PFC for negatively intense memories, but less recruitment for positively intense memories. Third, the PTSD group showed greater functional coupling between the ventral medial PFC and the amygdala for negatively intense memories, but less coupling for positively intense memories. In sum, the fMRI data suggest that there was greater recruitment and coupling of emotional brain regions during the retrieval of negatively intense AMs in the PTSD group when compared to controls.

Comparison of finite element and finite volume methods application in geometrically nonlinear stress analysis

A novel three-dimensional finite volume (FV) procedure is described in detail for the analysis of geometrically nonlinear problems. The FV procedure is compared with the conventional finite element (FE) Galerkin approach. FV can be considered to be a particular case of the weighted residual method with a unit weighting function, where in the FE Galerkin method we use the shape function as weighting function. A Fortran code has been developed based on the finite volume cell vertex formulation. The formulation is tested on a number of geometrically nonlinear problems. In comparison with FE, the results reveal that FV can reach the FE results in a higher mesh density.

Modelling of dosator operation for improved manufacturing performance

Purpose: To develop an improved mathematical model for the prediction of dose accuracy of Dosators - based upon the geometry of the machine in conjunction with measured flow properties of the powder. Methods: A mathematical model has been created, based on a analytical method of differential slices - incorporating measured flow properties. The key flow properties of interest in this investigation were: flow function, effective angle of wall friction, wall adhesion, bulk density, stress ratio K and permeability. To simulate the real process and (very importantly) validate the model, a Dosator test-rig has been used to measure the forces acting on the Dosator during the filling stage, the force required to eject the dose and the dose weight. Results: Preliminary results were obtained from the Dosator test-rig. Figure 1 [Omitted] shows the dose weight for different depths to the bottom of the powder bed at the end of the stroke and different levels of pre-compaction of the powder bed. A strong influence over dose weight arising from the proximity between the Dosator and the bottom of the powder bed at the end of the stroke and the conditions of the powder bed has been established. Conclusions: The model will provide a useful tool to predict dosing accuracy and, thus, optimise the future design of Dosator based equipment technology – based on measured bulk properties of the powder to be handled. Another important factor (with a significant influence) on Dosator processes, is the condition of the powder bed and the clearance between the Dosator and the bottom of the powder bed.

Microabrasion : A novel method to assess surface degradation of UHMWPE following sterilisation and ageing

The ageing behaviour of ultra-high molecular weight polyethylene (UHMWPE) has been studied following gamma irradiation (25 or 40 kGy) in air. Accelerated ageing procedures used elevated temperature (70°C) and/or pressurised oxygen (5 bar). Shelf-aged UHMWPE was also studied. The variation in surface density and mechanical properties were determined following the various sterilisation and ageing treatments. Microabrasive wear testing was also performed. Wear rates were found to correlate well with stress at break for sterilised and aged UHMWPE but not with elongation to failure. It is proposed that the wear mechanism is fracture dominated and occurs following some disentanglement of the polymer chains. Wear also depends upon embrittlement of the surface layer due to its processing and ageing. Elongation to failure in a tensile test is not a good measure of this embrittlement whereas the microabrasion test provides more surface sensitive information concerning this property.

Towards An Acoustic Model-Based Poroelastic Imaging Method: I. Theoretical Foundation

The ultrasonic measurement and imaging of tissue elasticity is currently under wide investigation and development as a clinical tool for the assessment of a broad range of diseases, but little account in this field has yet been taken of the fact that soft tissue is porous and contains mobile fluid. The ability to squeeze fluid out of tissue may have implications for conventional elasticity imaging, and may present opportunities for new investigative tools. When a homogeneous, isotropic, fluid-saturated poroelastic material with a linearly elastic solid phase and incompressible solid and fluid constituents is subjected to stress, the behaviour of the induced internal strain field is influenced by three material constants: the Young's modulus (E(s)) and Poisson's ratio (nu(s)) of the solid matrix and the permeability (k) of the solid matrix to the pore fluid. New analytical expressions were derived and used to model the time-dependent behaviour of the strain field inside simulated homogeneous cylindrical samples of such a poroelastic material undergoing sustained unconfined compression. A model-based reconstruction technique was developed to produce images of parameters related to the poroelastic material constants (E(s), nu(s), k) from a comparison of the measured and predicted time-dependent spatially varying radial strain. Tests of the method using simulated noisy strain data showed that it is capable of producing three unique parametric images: an image of the Poisson's ratio of the solid matrix, an image of the axial strain (which was not time-dependent subsequent to the application of the compression) and an image representing the product of the aggregate modulus E(s)(1-nu(s))/(1+nu(s))(1-2nu(s)) of the solid matrix and the permeability of the solid matrix to the pore fluid. The analytical expressions were further used to numerically validate a finite element model and to clarify previous work on poroelastography.

Development of a rapid screening test for veterinary sedatives and the beta-blocker carazolol in porcine kidney by ELISA

Sedatives and tranquillisers are frequently used to reduce stress during the transportation of food producing animals. The most widely used classes of sedatives include the butyrophenone azaperone, the phenothiazines acepromazine, propionylpromazine, chlorpromazine and the beta-blocker, carazolol. For regulatory control purposes, tolerances for azaperone and carazolol have been set by the European Union as 100 and 25 mug kg(-1), respectively. Furthermore, the use of the phenothiazines is prohibited and therefore has a zero tolerance. A method for the detection of residues of five tranquillisers and one beta-blocker using a single ELISA plate has been developed. Kidney samples (2.5 g) were extracted with dichloromethane and applied to a competitive enzyme immunoassay using three polyclonal antibodies raised in rabbits against azaperol, propionylpromazine and carazolol conjugates. In sample matrix, the azaperol antibody cross-reacted 28.0% with azaperone and the propionylpromazine antibody cross-reacted 24.9% with acepromazine and 11.7% with chlorpromazine. In the ELISA, the detection capabilities of the six sedatives, azaperol, azaperone, carazolol, acepromazine, chlorpromazine, and propionylpromazine are 5, 15, 5, 5, 20 and 5 mug kg(-1), respectively. The proposed method is a sensitive and rapid multi-residue technique that offers a cost effective alternative to current published procedures, without any concession on the ability to detect sedative misuse.

Comment on "Electron collisional excitation of argon-like Ni XI using the Breit-Pauli R-matrix method" [Eur. Phys. J. D 42, 235-241 (2007)] - Electron impact excitation of Ni XI

In a recent paper, Verma et al. [Eur. Phys. J. D 42, 235 (2007)] have reported results for energy levels, radiative rates, collision strengths, and effective collision strengths for transitions among the lowest 17 levels of the (1s(2)2s(2)2p(6))3s(2)3p(6), 3s(2)3p(5)3d and 3s3p(6)3d configurations of Ni XI. They adopted the CIV3 and R-matrix codes for the generation of wavefunctions and the scattering process, respectively. In this paper, through two independent calculations performed with the fully relativistic DARC (along with GRASP) and FAC codes, we demonstrate that their results are unreliable. New data are presented and their accuracy is assessed.

Application of Heuristic Evaluation Method by Universal Design Experts

This study highlights how heuristic evaluation as a usability evaluation method can feed into current building design practice to conform to universal design principles. It provides a definition of universal usability that is applicable to an architectural design context. It takes the seven universal design principles as a set of heuristics and applies an iterative sequence of heuristic evaluation in a shopping mall, aiming to achieve a cost-effective evaluation process. The evaluation was composed of three consecutive sessions. First, five evaluators from different professions were interviewed regarding the construction drawings in terms of universal design principles. Then, each evaluator was asked to perform the predefined task scenarios. In subsequent interviews, the evaluators were asked to re-analyze the construction drawings. The results showed that heuristic evaluation could successfully integrate universal usability into current building design practice in two ways: (i) it promoted an iterative evaluation process combined with multi-sessions rather than relying on one evaluator and on one evaluation session to find the maximum number of usability problems, and (ii) it highlighted the necessity of an interdisciplinary ad hoc committee regarding the heuristic abilities of each profession. A multi-session and interdisciplinary heuristic evaluation method can save both the project budget and the required time, while ensuring a reduced error rate for the universal usage of the built environments.

Index of sources of stress in nursing students: a confirmatory factor analysis.

Aim. This paper is a report of a study to test the proposed factor structure of the Index of Sources of Stress in Nursing Students. Background. Research across many countries has identified a number of sources of distress in nursing students but little attempt has been made to understand and measure sources of eustress or those stressors likely to enhance performance and well-being. The Index of Sources of Stress in Nursing Students was developed to do this. Exploratory factor analysis suggested a three-factor structure, the factors being labelled: learning and teaching; placement-related and course organization. It is important, however, to subject the instrument to confirmatory factor analysis as a further test of construct validity. Method. A convenience sample of final year nursing students (n = 176) was surveyed in one university in Northern Ireland in 2007. The Index of Sources of Stress in Nursing Students, which measures sources of stress likely to contribute to distress and eustress, was completed electronically. The LISREL programme was used to carry out the confirmatory factor analysis and test the factor structure suggested in the exploratory analysis. Findings. The proposed factor structure for the items measuring ‘Uplifts’ proved to be a good fit to the data and the proposed factor structure for the items measuring ‘Hassles’ showed adequate fit. Conclusion. In nursing programmes adopting the academic model and combining university-based learning with placement experience, this instrument can be used to help identify the sources of stress or course demands that students rate as distressing and those that help them to achieve. The validity of the ISSN could be further evaluated in other education settings.

Changes in surface stress caused by the adsorption of an epitaxial metal monolayer

The adsorption of a metal monolayer on a foreign substrate generates a change in the surface stress. We calculate this change for a number of substrate/adsorbate systems using the embedded-atom method. The results are compared with those obtained from a continuum model. A cycle, in which the stretching of a substrate/adsorbate system is decomposed into several steps, helps in understanding the numerical results. (C) 2000 Elsevier Science B.V. All rights reserved.