Sample records for stress-strain response characteristics

  1. Stress-strain response of plastic waste mixed soil.

    Babu, G L Sivakumar; Chouksey, Sandeep Kumar


    Recycling plastic waste from water bottles has become one of the major challenges worldwide. The present study provides an approach for the use plastic waste as reinforcement material in soil. The experimental results in the form of stress-strain-pore water pressure response are presented. Based on experimental test results, it is observed that the strength of soil is improved and compressibility reduced significantly with addition of a small percentage of plastic waste to the soil. The use of the improvement in strength and compressibility response due to inclusion of plastic waste can be advantageously used in bearing capacity improvement and settlement reduction in the design of shallow foundations. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Origins of asymmetric stress-strain response in phase transformations

    Sehitoglu, H.; Gall, K. [Univ. of Illinois, Urbana, IL (United States)


    It has been determined that the transformation stress-strain behavior of CuZnAl and NiTi shape memory alloys is dependent on the applied stress state. The uniaxial compressive stress necessary to macroscopically trigger the transformation is approximately 34% (CuZnAl) and 26% (NiTi) larger than the required uniaxial tensile stress. For three dimensional stress states, the response of either alloy system is dependent on the directions of the dominant principal stresses along with the hydrostatic stress component of the stress state. The stress state effects are dominated by the favored growth and nucleation of more martensite plates in tension versus compression. The effect of different hydrostatic pressure levels between stress states on martensite plates volume change is considered small.

  3. Stress-strain characteristics of materials at high strain rates. Part II. Experimental results

    Ripperger, E. A. [Texas. Univ., Austin, TX (US). Structural Mechanics Research Lab.


    These two reports were issued separately, but are cataloged as a unit. A photoelectric method for measuring displacements during high-velocity impacts is described. The theory of the system is discussed in detail, and a prototype system which was built and tested is described. The performance of the prototype system is evaluated by comparing the results which it gives with results obtained by other methods of measurement. The system was found capable of a resolution of at least 0.01 inches. static and dynamic stress-strain characteristics of seven high polymers, polyethylene, teflon, nylon, tenite M, tenite H, polystyrene, and saran, plus three metals, lead, copper, and aluminum, are described and compared by means of stress-strain curves and photographs. Data are also presented which show qualitatively the effects produced on stress-strain characteristics by specimen configuration, temperature, and impact velocity. It is shown that there is a definite strain-rate effect for all these materials except polystyrene. The effect is one of an apparent stiffening of the material with increasing strain rate, which is similar to the effect produced by lowering the temperature. The stress-strain measurements are examined critically, inconsistencies are pointed out, and possible sources of error suggested. Values of yield stress, modulus of elasticity and energy absorption for all materials (except copper and aluminum), specimen configurations, temperatures, and impact velocities included in the investigation are tabulated.

  4. Relationship between fatigue life in the creep-fatigue region and stress-strain response

    Berkovits, A.; Nadiv, S.


    On the basis of mechanical tests and metallographic studies, strainrange partitioned lives were predicted by introducing stress-strain materials parameters into the Universal Slopes Equation. This was the result of correlating fatigue damage mechanisms and deformation mechanisms operating at elevated temperatures on the basis of observed mechanical and microstructural behavior. Correlation between high temperature fatigue and stress strain properties for nickel base superalloys and stainless steel substantiated the method. Parameters which must be evaluated for PP- and CC- life are the maximum stress achievable under entirely plastic and creep conditions respectively and corresponding inelastic strains, and the two more pairs of stress strain parameters must be ascertained.

  5. Coarse-graining scheme for simulating uniaxial stress-strain response of glassy polymers through molecular dynamics.

    Majumder, Manoj K; S, Ramkumar; Mahajan, Dhiraj K; Basu, Sumit


    Simulation of the deformation of polymers below their glass transition through molecular dynamics provides an useful route to correlate their molecular architecture to deformation behavior. However, present computational capabilities severely restrict the time and length scales that can be simulated when detailed models of these macromolecules are used. Coarse-graining techniques for macromolecular structures intend to make bigger and longer simulations possible by grouping atoms into superatoms and devising ways of determining reasonable force fields for the superatoms in a manner that retains essential macromolecular features relevant to the process under study but jettisons unnecessary details. In this work we systematically develop a coarse-graining scheme aimed at simulating uniaxial stress-strain behavior of polymers below their glass transition. The scheme involves a two step process of obtaining the coarse grained force field parameters above glass transition. This seems to be enough to obtain "faithful" stress-strain responses after quenching to below the glass transition temperature. We apply the scheme developed to a commercially important polymer polystyrene, derive its complete force field parameters and thus demonstrate the effectiveness of the technique.

  6. Characterization of Multiaxial Stress-Strain Response of Tube Metal from Double-Sided Hydro-Bulging Test Based on Hosford's 1979 Yield Criterion

    Cui, Xiao-Lei; Yang, Zhai-Ping; Wang, Xiao-Song


    To further explore the characterization of the multiaxial stress-strain responses of anisotropic tube metal from double-sided hydro-bulging tests, an analytical model for the equivalent stress and equivalent strain calculation was derived based on Hosford's 1979 yield criterion. Furthermore, thin-walled 5052-O aluminum alloy tubes were used to conduct the bulging experiment with an external pressure of 85 MPa. After the experimental data were substituted into the above analytical model, the Voce equation was used to fit the equivalent stress-strain relationship. It is concluded that the stress versus strain curves of the 5052-O tubes are strongly dependent on the loaded stress states, the adopted yield criteria, and the anisotropy coefficients. The external pressure of 85 MPa had little or no effect on the stress versus strain curves of the tubes, but the locations of the multiaxial stress versus strain curves were lower than that of the uniaxial stress versus strain curve. Moreover, the curve from Hosford's 1979 yield criterion not only had a higher saturation stress and material constant value than the curve from Mises and Hill's 1948 yield criteria but also had a dependence on the anisotropy coefficient.

  7. A deep learning approach to estimate chemically-treated collagenous tissue nonlinear anisotropic stress-strain responses from microscopy images.

    Liang, Liang; Liu, Minliang; Sun, Wei


    Biological collagenous tissues comprised of networks of collagen fibers are suitable for a broad spectrum of medical applications owing to their attractive mechanical properties. In this study, we developed a noninvasive approach to estimate collagenous tissue elastic properties directly from microscopy images using Machine Learning (ML) techniques. Glutaraldehyde-treated bovine pericardium (GLBP) tissue, widely used in the fabrication of bioprosthetic heart valves and vascular patches, was chosen to develop a representative application. A Deep Learning model was designed and trained to process second harmonic generation (SHG) images of collagen networks in GLBP tissue samples, and directly predict the tissue elastic mechanical properties. The trained model is capable of identifying the overall tissue stiffness with a classification accuracy of 84%, and predicting the nonlinear anisotropic stress-strain curves with average regression errors of 0.021 and 0.031. Thus, this study demonstrates the feasibility and great potential of using the Deep Learning approach for fast and noninvasive assessment of collagenous tissue elastic properties from microstructural images. In this study, we developed, to our best knowledge, the first Deep Learning-based approach to estimate the elastic properties of collagenous tissues directly from noninvasive second harmonic generation images. The success of this study holds promise for the use of Machine Learning techniques to noninvasively and efficiently estimate the mechanical properties of many structure-based biological materials, and it also enables many potential applications such as serving as a quality control tool to select tissue for the manufacturing of medical devices (e.g. bioprosthetic heart valves). Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  8. Effect of internal heating during hot compression testing on the stress-strain behavior and hot working characteristics of Alloy 304L

    Mataya, M.C.; Sackschewsky, V.E.


    Temperature change from conversion of deformation to internal heat, and its effect on stress-strain behavior of alloy 304L was investigated by initially isothermal (temperature of specimen, compression dies, environment equilibrated at initiation of test) uniaxial compression. Strain rate was varied 0.01 s{sup {minus}1} to 1 s{sup {minus}1} (thermal state of specimen varied from nearly isothermal to nearly adiabatic). Specimens were deformed at 750 to 1150 to a strain of 1. Change in temperature with strain was calculated via finite element analysis from measured stress-strain data and predictions were confirmed with thermocouples to verify the model. Temperature increased nearly linearly at the highest strain rate, consistent with temperature rise being a linear function of strain (adiabatic). As strain rate was lowered, heat transfer from superheated specimen to cooler dies caused sample temperature to increase and then decrease with strain as the sample thinned and specimen-die contact area increased. As-measured stress was corrected. Resulting isothermal flow curves were compared to predictions of a simplified method suggested by Thomas and Shrinivasan and differences are discussed. Strain rate sensitivity, activation energy for deformation, and flow curve peak associated with onset of dynamic recrystallization were determined from both as-measured and isothermal stress-strain data and found to vary widely. The impact of utilizing as-measured stress-strain data, not corrected for internal heating, on results of a number of published investigations is discussed.

  9. The Correlation Between the Percussive Sound and the Residual Stress/Strain Distributions in a Cymbal

    Osamura, Kozo; Kuratani, Fumiyasu; Koide, Toshio; Ogawa, Wataru; Taniguchi, Hiroyasu; Monju, Yoshiyuki; Mizuta, Taiji; Shobu, Takahisa


    The artistic sound of a cymbal is produced by employing a special copper alloy as well as incorporating complicated and heterogeneous residual stress/strain distributions. In order to establish a modern engineering process that achieves high-quality control for the cymbals, it is necessary to investigate the distribution of the residual stresses/strains in the cymbal and their quantitative relation with the frequency characteristics of the sound generated from the cymbal. In the present study, we have successfully used synchrotron radiation to measure the distribution of residual strain in two kinds of cymbals—after spinforming as well as after hammering. The microstructure and the mechanical properties of the cymbals were measured as well their acoustic response. Based on our experimental data, the inhomogeneous residual stress/strain distributions in the cymbals were deduced in detail and their influence on the frequency characteristics of the sound produced by the cymbals was identified.

  10. Effects of the foil flatness on the stress-strain characteristics of U10Mo alloy based monolithic mini-plates

    Hakan Ozaltun; Pavel Medvedev


    The effects of the foil flatness on stress-strain behavior of monolithic fuel mini-plates during fabrication and irradiation were studied. Monolithic plate-type fuels are a new fuel form being developed for research and test reactors to achieve higher uranium densities. This concept facilitates the use of low-enriched uranium fuel in the reactor. These fuel elements are comprised of a high density, low enrichment, U–Mo alloy based fuel foil encapsulated in a cladding material made of Aluminum. To evaluate the effects of the foil flatness on the stress-strain behavior of the plates during fabrication, irradiation and shutdown stages, a representative plate from RERTR-12 experiments (Plate L1P756) was considered. Both fabrication and irradiation processes of the plate were simulated by using actual irradiation parameters. The simulations were repeated for various foil curvatures to observe the effects of the foil flatness on the peak stress and strain magnitudes of the fuel elements. Results of fabrication simulations revealed that the flatness of the foil does not have a considerable impact on the post fabrication stress-strain fields. Furthermore, the irradiation simulations indicated that any post-fabrication stresses in the foil would be relieved relatively fast in the reactor. While, the perfectly flat foil provided the slightly better mechanical performance, overall difference between the flat-foil case and curved-foil case was not significant. Even though the peak stresses are less affected, the foil curvature has several implications on the strain magnitudes in the cladding. It was observed that with an increasing foil curvature, there is a slight increase in the cladding strains.

  11. 陷落柱填隙物全应力-应变过程的渗流特性研究%Research on permeability characteristics of karst collapse column fillings in complete stress-strain process

    张勃阳; 白海波; 张凯


    岩溶陷落柱易导通含水层与煤层从而引发底板突水事故,已经成为我国华北地区下组煤开采的重要安全隐患。对于固结良好的陷落柱,其填隙物的渗透性直接影响着陷落柱的整体渗透性,且在采动压力的影响下,陷落柱填隙物的渗透性也在不断发生变化。为研究不同应力状态下填隙物渗透率的变化规律,对填隙物进行固结重塑,并利用MTS815.02渗流试验系统对重塑后不同初始含水率的填隙物试样进行了不同围压条件下的全应力-应变过程的渗流特性试验。试验结果表明:1)陷落柱填隙物全应力-应变过程渗透率的变化曲线可划分为压密段、破坏段和蠕变段,渗透率对应的呈现出减小-增大-减小的变化规律;2)填隙物的全应力-应变过程的渗透率峰值随围压的增大而减小,其峰值比与围压差存在指数函数关系;3)填隙物的初始渗透率和孔隙度随初始含水率的增大而增大,渗透率比和孔隙度比存在幂函数关系,在全应力-应变过程中渗透率峰值与初始值的差随初始含水率的增大而减小。%The floor water-inrush accident caused by karst collapse column is easy to break over the aquifer and coal seam. This kind of accident has become the serious danger of lower group coal mining in northern China. For the well-consolidated collapse column, the permeability of the fillings directly affects that of the overall collapse column, and the permeability of fillings constantly changes under the influence of mining. The study on seepage characteristic of collapse column fillings is conducted with MTS815.02 seepage test system in a complete stress-strain process and the variation of permeability under different strain states. Meanwhile the influence of initial moisture content and confining pressure on the fillings permeability is analyzed in this test. The results show that: 1) The representative stress-strain

  12. Compressive Behavior and Mechanical Characteristics and Their Application to Stress-Strain Relationship of Steel Fiber-Reinforced Reactive Powder Concrete

    Baek-Il Bae


    Full Text Available Although mechanical properties of concrete under uniaxial compression are important to design concrete structure, current design codes or other empirical equations have clear limitation on the prediction of mechanical properties. Various types of fiber-reinforced reactive powder concrete matrix were tested for making more usable and accurate estimation equations for mechanical properties for ultra high strength concrete. Investigated matrix has compressive strength ranged from 30 MPa to 200 MPa. Ultra high strength concrete was made by means of reactive powder concrete. Preventing brittle failure of this type of matrix, steel fibers were used. The volume fraction of steel fiber ranged from 0 to 2%. From the test results, steel fibers significantly increase the ductility, strength and stiffness of ultra high strength matrix. They are quantified with previously conducted researches about material properties of concrete under uniaxial loading. Applicability of estimation equations for mechanical properties of concrete was evaluated with test results of this study. From the evaluation, regression analysis was carried out, and new estimation equations were proposed. And these proposed equations were applied into stress-strain relation which was developed by previous research. Ascending part, which was affected by proposed equations of this study directly, well fitted into experimental results.

  13. Tensile stress-strain behavior of hybrid composite laminates

    Kennedy, J. M.


    A study was made of the stress-strain response of several hybrid laminates, and the damage was correlated with nonlinear stress-strain response and ultimate strength. The fibers used in the laminates were graphite, S-glass, and Kevlar. Some laminates with graphite fibers had perforated Mylar film between plies, which lowered the interlaminar bond strength. The laminate configurations were chosen to be like those of buffer strips in large panels and fracture coupons. Longitudinal and transverse specimens were loaded in tension to failure. Some specimens were radiographed to reveal damage due to edge effects. Stress-strain response is discussed in terms of damage shown by the radiographs. Ultimate strengths are compared with simple failure criteria, one of which account for damage.

  14. Measurement of the stress/strain response of energetic materials as a function of strain rate and temperature: PBX 9501 and Mock 9501

    Funk, D.J.; Laabs, G.W.; Peterson, P.D.; Asay, B.W.


    We have measured the stress/strain behavior of PBX 9501, Mock 900-21 and two new mocks consisting of monoclinic granular sugar embedded in (1) a BDNPA-F/estane binder (a 9501 material mock; a hard organic crystal embedded in a plastic) and (2) neat estane (an LX-14 mock) at strain rates from 10{sup -3} to 10{sup -1}, at two L/D`s and at two temperatures (25 and 60 C). We find that the compressive strength falls with increasing temperature and rises with increasing strain rate. We also find that the new 9501 sugar mock most closely resembles the behavior of the 9501 explosive and differences may be attributable to the different ages of the estane binder used.

  15. Atlas of stress-strain curves


    The Atlas of Stress-Strain Curves, Second Edition is substantially bigger in page dimensions, number of pages, and total number of curves than the previous edition. It contains over 1,400 curves, almost three times as many as in the 1987 edition. The curves are normalized in appearance to aid making comparisons among materials. All diagrams include metric (SI) units, and many also include U.S. customary units. All curves are captioned in a consistent format with valuable information including (as available) standard designation, the primary source of the curve, mechanical properties (including hardening exponent and strength coefficient), condition of sample, strain rate, test temperature, and alloy composition. Curve types include monotonic and cyclic stress-strain, isochronous stress-strain, and tangent modulus. Curves are logically arranged and indexed for fast retrieval of information. The book also includes an introduction that provides background information on methods of stress-strain determination, on...


    Y.F. Guo; Y.Z. Huo; G.T. Zeng; X.T. Zu


    A six-parameter mathematical model was introduced to simulate the stress-strain hysteresis and the inner hysteresis of polycrystalline shape memory alloys (SMAs). By comparing with experiments of Cu-Zn-Al SMA, it was shown that the model could be used to calculate the stress-strain relations with rather good accuracy. Moreover,it was found that the six parameters introduced in this paper represented the characteristics of the stress-strain hysteresis of polycrystalline SMA and can be used to characterize the hysteresis quantitatively.

  17. BILAM: a composite laminate failure-analysis code using bilinear stress-strain approximations

    McLaughlin, P.V. Jr.; Dasgupta, A.; Chun, Y.W.


    The BILAM code which uses constant strain laminate analysis to generate in-plane load/deformation or stress/strain history of composite laminates to the point of laminate failure is described. The program uses bilinear stress-strain curves to model layer stress-strain behavior. Composite laminates are used for flywheels. The use of this computer code will help to develop data on the behavior of fiber composite materials which can be used by flywheel designers. In this program the stress-strain curves are modelled by assuming linear response in axial tension while using bilinear approximations (2 linear segments) for stress-strain response to axial compressive, transverse tensile, transverse compressive and axial shear loadings. It should be noted that the program attempts to empirically simulate the effects of the phenomena which cause nonlinear stress-strain behavior, instead of mathematically modelling the micromechanics involved. This code, therefore, performs a bilinear laminate analysis, and, in conjunction with several user-defined failure interaction criteria, is designed to provide sequential information on all layer failures up to and including the first fiber failure. The modus operandi is described. Code BILAM can be used to: predict the load-deformation/stress-strain behavior of a composite laminate subjected to a given combination of in-plane loads, and make analytical predictions of laminate strength.

  18. Spherical nanoindentation stress-strain analysis, Version 1


    Nanoindentation is a tool that allows the mechanical response of a variety of materials at the nano to micron length scale to be measured. Recent advances in spherical nanoindentation techniques have allowed for a more reliable and meaningful characterization of the mechanical response from nanoindentation experiments in the form on an indentation stress-strain curve. This code base, Spin, is written in MATLAB (The Mathworks, Inc.) and based on the analysis protocols developed by S.R. Kalidindi and S. Pathak [1, 2]. The inputs include the displacement, load, harmonic contact stiffness, harmonic displacement, and harmonic load from spherical nanoindentation tests in the form of an Excel (Microsoft) spreadsheet. The outputs include indentation stress-strain curves and indentation properties as well their variance due to the uncertainty of the zero-point correction in the form of MATLAB data (.mat) and figures (.png). [1] S. Pathak, S.R. Kalidindi. Spherical nanoindentation stress–strain curves, Mater. Sci. Eng R-Rep 91 (2015). [2] S.R. Kalidindi, S. Pathak. Determination of the effective zero-point and the extraction of spherical nanoindentation stress-strain curves, Acta Materialia 56 (2008) 3523-3532.

  19. Cyclic stress-strain behaviour under thermomechanical fatigue conditions - Modeling by means of an enhanced multi-component model

    Christ, H J [Institut fuer Werkstofftechnik, Universitaet Siegen, D-57068 Siegen (Germany); Bauer, V, E-mail: hans-juergen.christ@uni-siegen.d [Wieland Werke AG, Graf-Arco Str. 36, D-89072 Ulm (Germany)


    The cyclic stress-strain behaviour of metals and alloys in cyclic saturation can reasonably be described by means of simple multi-component models, such as the model based on a parallel arrangement of elastic-perfectly plastic elements, which was originally proposed by Masing already in 1923. This model concept was applied to thermomechanical fatigue loading of two metallic engineering materials which were found to be rather oppositional with respect to cyclic plastic deformation. One material is an austenitic stainless steel of type AISI304L which shows dynamic strain aging (DSA) and serves as an example for a rather ductile alloy. A dislocation arrangement was found after TMF testing deviating characteristically from the corresponding isothermal microstructures. The second material is a third-generation near-gamma TiAl alloy which is characterized by a very pronounced ductile-to-brittle transition (DBT) within the temperature range of TMF cycling. Isothermal fatigue testing at temperatures below the DBT temperature leads to cyclic hardening, while cyclic softening was found to occur above DBT. The combined effect under TMF leads to a continuously developing mean stress. The experimental observations regarding isothermal and non-isothermal stress-strain behaviour and the correlation to the underlying microstructural processes was used to further develop the TMF multi-composite model in order to accurately predict the TMF stress-strain response by taking the alloy-specific features into account.

  20. Influence of discontinuities on the rock mass stress-strain state around excavation

    V.N. Bukhartsev


    Full Text Available Adequate mathematical modeling of selvage zone and natural fracturing as well as assessment of its impact on stress-strain state – urgent problems in calculation of hydraulic tunnels. Modern Russian regulations in fact give dependences only to solve the problems in plane deformation conditions. The specificity of work of the tunnel that crosses the discontinuity, as a space frame are not taken into account. This article presents influence of discontinuities and fracture characteristics on the rock mass stress-strain state around excavation. Fractured rock mass model was analyzed. Formula of modulus of elasticity for fractured rock mass at distance from the fault was deduced. Influence of discontinuities on the stress distribution was estimated with using experiment design method. On the basis of the conducted research it was established, that assessing rock stress-strain state around the fracture is necessary to consider rock mass fracture characteristics; and using principal stresses distribution in combination with Lode parameter we can clearly estimate the type of stress-strain state in each point, therefore, we can use different strength theories for different sections of the tunnel.

  1. An experimental study on stress-strain behavior and constitutive model of hardfill material

    Wu, Mengxi; Du, Bin; Yao, Yuancheng; He, Xianfeng


    Hardfill is a new type of artificially cemented material for dam construction works, with a wide application prospect. Its mechanical behavior lies between concrete and rockfill materials. A series of large-scale triaxial tests are performed on hardfill specimens at different ages, and the stress-strain behavior of hardfill is further discussed. The strength and stress-strain relationship of hardfill materials show both frictional mechanism and cohesive mechanism. An age-related constitutive model of hardfill is developed, which is a parallel model consisting of two components, rockfill component and cementation component. Moreover, a comparison is made between the simulated and the experimental results, which shows that the parallel model can reflect the mechanical characteristics of both rockfill-like nonlinearity and concrete-like age relativity. In addition, a simplified method for the determination of parameters is proposed.

  2. Theoretical and experimental study on relationship between stress-strain and temperature variation


    Principle on temperature response to the stress-strain variation is fundamental to the relationship between thermal radiation variation and stress-strain field. Current research indicates that temperature has a sensitive response to rock deformation under the condition of normal temperature background. However, the basic physical relationship between deformation and temperature variation is not clear and need to be investigated further. In this paper, principle on temperature response to stress-strain variation is studied in detail, based on thermodynamics, elastic strain theory, and experiments on both ideal material and rock. In the stage of elastic deformation, results indicate that: 1) temperature increment is positively correlated with volume strain variation. Temperature rises with hydrostatic pressure increase. In other words, temperature rises when the specimen is under the compressive state whereas temperature drops under the tensile state. 2) Pure shear deformation does not contribute to tempera- ture variation. Namely, shape change of specimen does not produce temperature variation. However, there exist the relative tensile area and the compressive one in the specimen under the state of pure shear. Temperature drops within the relative tensile area while temperature rises within the compressive areas during the process of loading.

  3. Theoretical and experimental study on relationship between stress-strain and temperature variation

    CHEN ShunYun; LIU LiQiang; LIU PeiXun; MA Jin; CHEN GuoQiang


    Principle on temperature response to the stress-strain variation is fundamental to the relationship between thermal radiation variation and stress-strain field.Current research indicates that temperature has a sensitive response to rock deformation under the condition of normal temperature background.However,the basic physical relationship between deformation and temperature variation is not clear and need to be investigated further.In this paper,principle on temperature response to stress-strain variation is studied in detail,based on thermodynamics,elastic strain theory,and experiments on both ideal material and rock.In the stage of elastic deformation,results indicate that:1) temperature increment is positively correlated with volume strain variation.Temperature rises with hydrostatic pressure increase.In other words,temperature rises when the specimen is under the compressive state whereas temperature drops under the tensile state.2) Pure shear deformation does not contribute to temperature variation.Namely,shape change of specimen does not produce temperature variation.However,there exist the relative tensile area and the compressive one in the specimen under the state of pure shear.Temperature drops within the relative tensile area while temperature rises within the compressive areas during the process of loading.

  4. Incremental stress-strain law for graphite under multiaxial loadings

    Tzung, F.


    An incremental stress-strain law for describing the nonlinear, compressible and asymmetric behavior of graphite under tension and compression as well as complex loadings is derived based on a dry friction model in the theory of plasticity. Stress-strain relations are defined by longitudinal-lateral strain measurements for specimens under uniaxial tension-compression. Agreements with experimentally determined curves from biaxial loading experiments are shown. Agreements in finite element computations using the present model with strain measurements for diametral compression and 4-point bend tests of graphite are also obtained.

  5. Unified analytical stress- strain curve for quasibrittle geomaterial in uniaxial tension, direct shear and uniaxial compression


    Considering strain localization in the form of a narrow band initiated just at peak stress, three analytical expressions for stress- strain curves of quasibrittle geomaterial (such as rock and concrete) in uniaxial tension, direct shear and uniaxial compression were presented, respectively. The three derived stress- strain curves were generalized as a unified formula. Beyond the onset of strain localization, a linear strain-softening constitutive relation for localized band was assigned. The size of the band was controlled by internal or characteristic length according to gradient-dependent plasticity. Elastic strain within the entire specimen was assumed to be uniform and decreased with the increase of plastic strain in localized band. Total strain of the specimen was decomposed into elastic and plastic parts. Plastic strain of the specimen was the average value of plastic strains in localized band over the entire specimen. For different heights, the predicted softening branches of the relative stress - strain curves in uniaxial compression are consistent with the previously experimental results for normal concrete specimens. The present expressions for the post-peak stress - deformation curves in uniaxial tension and direct shear agree with the previously numerical results based on gradient-dependent plasticity.

  6. A comparative study on the elastic modulus of polyvinyl alcohol sponge using different stress-strain definitions.

    Karimi, Alireza; Navidbakhsh, Mahdi; Alizadeh, Mansour; Razaghi, Reza


    There have been different stress-strain definitions to measure the elastic modulus of spongy materials, especially polyvinyl alcohol (PVA) sponge. However, there is no agreement as to which stress-strain definition should be implemented. This study was aimed to show how different results are given by the various definitions of stress-strain used, and to recommend a specific definition when testing spongy materials. A fabricated PVA sponge was subjected to a series of tensile tests in order to measure its mechanical properties. Three stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) were used to determine the elastic modulus. The results revealed that the Almansi-Hamel strain definition exhibited the highest non-linear stress-strain relation and, as a result, may overestimate the elastic modulus at different stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress). The Green-St. Venant strain definition failed to address the non-linear stress-strain relation using different definitions of stress and invoked an underestimation of the elastic modulus values. Engineering stress and strain definitions were only valid for small strains and displacements, which make them impractical when analyzing spongy materials. The results showed that the effect of varying the stress definition on the maximum stress measurements was significant but not when calculating the elastic modulus. It is important to consider which stress-strain definition is employed when characterizing the mechanical properties of spongy materials. Although the true stress-true strain definition exhibits a non-linear relation, we favor it in spongy materials mechanics as it gives more accurate measurements of the material's response using the instantaneous values.

  7. An experimental study on the mechanical properties of rat brain tissue using different stress-strain definitions.

    Karimi, Alireza; Navidbakhsh, Mahdi


    There are different stress-strain definitions to measure the mechanical properties of the brain tissue. However, there is no agreement as to which stress-strain definition should be employed to measure the mechanical properties of the brain tissue at both the longitudinal and circumferential directions. It is worth knowing that an optimize stress-strain definition of the brain tissue at different loading directions may have implications for neuronavigation and surgery simulation through haptic devices. This study is aimed to conduct a comparative study on different results are given by the various definitions of stress-strain and to recommend a specific definition when testing brain tissues. Prepared cylindrical samples are excised from the parietal lobes of rats' brains and experimentally tested by applying load on both the longitudinal and circumferential directions. Three stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) are used to determine the elastic modulus, maximum stress and strain. The highest non-linear stress-strain relation is observed for the Almansi-Hamel strain definition and it may overestimate the elastic modulus at different stress definitions at both the longitudinal and circumferential directions. The Green-St. Venant strain definition fails to address the non-linear stress-strain relation using different definitions of stress and triggers an underestimation of the elastic modulus. The results suggest the application of the true stress-true strain definition for characterization of the brain tissues mechanics since it gives more accurate measurements of the tissue's response using the instantaneous values.

  8. Numerical Evaluation of Size Effect on the Stress-Strain Behaviour of Geotextile-Reinforced Sand

    Hosseinpour, I.; Mirmoradi, S.H.; Barari, Amin;


    This paper studies the effect of sample size on the stress-strain behavior and strength characteristics of geotextile reinforced sand using the finite element numerical analysis. The effect of sample size was investigated by studying the effects of varying the number of geotextile layers...... axial strain at failure in comparison with large-sized samples. The size effect on the behavior of samples became further apparent when the number of geotextile layers was increased or the confining pressure was decreased. In addition, the results indicated that the magnitude of the size effect...

  9. Progress Report on Alloy 617 Isochronous Stress-Strain Curves

    Jill K. Wright; Richard N. Wright; Nancy J. Lybeck


    Isochronous stress-strain curves for Alloy 617 up to a temperature of 1000°C will be required to qualify the material for elevated temperature design in Section III, Division 1, Subsection NH of the ASME Boiler and Pressure Vessel Code. Several potential methods for developing these curves are reviewed in this report. It is shown that in general power-law creep is the rate controlling deformation mechanism for a wide range of alloy heats, test temperatures and stresses. Measurement of the strain rate sensitivity of Alloy 617 indicates that the material is highly strain rate sensitive in the tensile deformation range above about 750°C. This suggests that the concept of a hot tensile curve as a bounding case on the isochronous stress-strain diagrams is problematic. The impact of strain rate on the hot tensile curves is examined and it is concluded that incorporating such a curve is only meaningful if a single tensile strain rate (typically the ASTM standard rate of 0.5%/min) is arbitrarily defined. Current experimentally determined creep data are compared to isochronous stress-strain curves proposed previously by the German programs in the 1980s and by the 1990 draft ASME Code Case. Variability in how well the experimental data are represented by the proposed design curves that suggests further analysis is necessary prior to completing a new draft Code Case.

  10. Linear and nonlinear modulus surfaces in stress space, from stress-strain measurements on Berea sandstone

    M. Boudjema


    Full Text Available The elastic response of many rocks to quasistatic stress changes is highly nonlinear and hysteretic, displaying discrete memory. Rocks also display unusual nonlinear response to dynamic stress changes. A model to describe the elastic behavior of rocks and other consolidated materials is called the Preisach-Mayergoyz (PM space model. In contrast to the traditional analytic approach to stress-strain, the PM space picture establishes a relationship between the quasistatic data and a number density of hysteretic mesoscopic elastic elements in the rock. The number density allows us to make quantitative predictions of dynamic elastic properties. Using the PM space model, we analyze a complex suite of quasistatic stress-strain data taken on Berea sandstone. We predict a dynamic bulk modulus and a dynamic shear modulus surface as a function of mean stress and shear stress. Our predictions for the dynamic moduli compare favorably to moduli derived from time of flight measurements. We derive a set of nonlinear elastic constants and a set of constants that describe the hysteretic behavior of the sandstone.

  11. Stress-strain analysis of pipelines laid in permafrost

    Burkov, P.; Yan‘nan', Van; Burkova, S.


    Increasing reliability of pipelines becomes a real challenge at all stages: design, construction and operation of pipeline systems. It is very important to determine the behaviour of the constructed pipeline under the operational and environmental loads using the design model in accordance with that one adopted in the rules and regulations. This article presents the simulation of pipeline in permafrost. The evaluation of the stress-strain state is given herein and the areas of the stress concentration are detected with the account for different loads occurred during the pipeline operation. Information obtained from the assessment of the stress-strain state of the pipeline allows determining sections in pre-emergency state (even before damages) and take all the necessary measures for eliminating them, thus increasing the pipeline system reliability. It is shown that the most critical pipeline cross-section is observed at the point of transition from one environment to another. The maximum strains decrease the level of the pipeline reliability. The finite element model is presented to determine the pipeline sections in pre-emergency state.

  12. Analysis of stress-strain state of the spherical shallow shell with inclusion

    O.B. Kozin


    Full Text Available Development of effective methods of determining the stress-strain state thin-walled structures with inclusions, reinforcements and other stress concentrators is an important task, both from a theoretical and practical point of view, by reason of their great practical application. Aim: The aim of the research is to analyze the elastic-deformed state of a spherical shallow shell. Materials and Methods: In this work, based on the generalized scheme of integral transformations, a constructive method of direct numerical-analytical solutions of boundary value problem of calculating the stress-strain state of a spherical shallow shell with the inclusion in bending is proposed. Results: The results of numerical calculations are presented. Calculations allow predicting the value of deformation of the cylindrical shells structure with reinforcements and determining the optimum parameters for the design or manufacture. The obtained results can be used in determining the strength characteristics of structural elements that consist of composite materials. The article contains comparative analysis of the results and demonstrates the effectiveness of the method for solving this class of problems.

  13. Relations of complete creep processes and triaxial stress-strain curves of rock

    李云鹏; 王芝银; 唐明明; 王怡


    Based on the results of triaxial compressive creep tests for five kinds of rock under the different stress loading,unloading and cycle-loading-unloading conditions,the creep deformation is not only a function of stress and time,but also it has the corresponding relations to the triaxial stress-strain curves of rock.The deformation properties of soften-strain,harden-strain and ideal plasticity presented by conventional triaxial compressive test curves under the different stress states were utilized,and the creep characteristics,the creep starting stress and the different entire creep process curves of rock were studied systematically according to creep experiment results,and the relations of the triaxial stress-strain curves to the creeping starting stress,the terminating curve,the different creep processes,and the different creep fracture properties were established.The relations presented in this paper were verified partially by the creep experiment results of five types of rock.

  14. Modeling Stress Strain Relationships and Predicting Failure Probabilities For Graphite Core Components

    Duffy, Stephen [Cleveland State Univ., Cleveland, OH (United States)


    This project will implement inelastic constitutive models that will yield the requisite stress-strain information necessary for graphite component design. Accurate knowledge of stress states (both elastic and inelastic) is required to assess how close a nuclear core component is to failure. Strain states are needed to assess deformations in order to ascertain serviceability issues relating to failure, e.g., whether too much shrinkage has taken place for the core to function properly. Failure probabilities, as opposed to safety factors, are required in order to capture the bariability in failure strength in tensile regimes. The current stress state is used to predict the probability of failure. Stochastic failure models will be developed that can accommodate possible material anisotropy. This work will also model material damage (i.e., degradation of mechanical properties) due to radiation exposure. The team will design tools for components fabricated from nuclear graphite. These tools must readily interact with finite element software--in particular, COMSOL, the software algorithm currently being utilized by the Idaho National Laboratory. For the eleastic response of graphite, the team will adopt anisotropic stress-strain relationships available in COMSO. Data from the literature will be utilized to characterize the appropriate elastic material constants.

  15. Stress-strain behavior of cementitious materials with different sizes.

    Zhou, Jikai; Qian, Pingping; Chen, Xudong


    The size dependence of flexural properties of cement mortar and concrete beams is investigated. Bazant's size effect law and modified size effect law by Kim and Eo give a very good fit to the flexural strength of both cement mortar and concrete. As observed in the test results, a strong size effect in flexural strength is found in cement mortar than in concrete. A modification has been suggested to Li's equation for describing the stress-strain curve of cement mortar and concrete by incorporating two different correction factors, the factors contained in the modified equation being established empirically as a function of specimen size. A comparison of the predictions of this equation with test data generated in this study shows good agreement.

  16. Materials property testing using a stress-strain microprobe

    Panayotou, N.F.; Baldrey, D.G. [Lockheed Martin Corp., Schenectady, NY (United States); Haggag, F.M. [Advanced Technology Corp., Oak Ridge, TN (United States)


    The Stress-Strain Microprobe (SSM) uses an automated ball indentation technique to obtain flow data from a localized region of a test specimen or component. This technique is used to rapidly determine the yield strength and microstructural condition of a variety of materials including pressure vessel steels, stainless steels, and nickel-base alloys. The SSM provides an essentially non-destructive technique for the measurement of yield strength data. This technique is especially suitable for the study of complex or highly variable microstructures such as weldments and weld heat affected zones. In this study 119 distinct SSM determinations of the yield strength of eight engineering alloys are discussed and compared to data obtained by conventional tensile tests. The sensitivity of the SSM to the presence of residual stresses is also discussed.

  17. Modeling the Stress Strain Behavior of Woven Ceramic Matrix Composites

    Morscher, Gregory N.


    Woven SiC fiber reinforced SiC matrix composites represent one of the most mature composite systems to date. Future components fabricated out of these woven ceramic matrix composites are expected to vary in shape, curvature, architecture, and thickness. The design of future components using woven ceramic matrix composites necessitates a modeling approach that can account for these variations which are physically controlled by local constituent contents and architecture. Research over the years supported primarily by NASA Glenn Research Center has led to the development of simple mechanistic-based models that can describe the entire stress-strain curve for composite systems fabricated with chemical vapor infiltrated matrices and melt-infiltrated matrices for a wide range of constituent content and architecture. Several examples will be presented that demonstrate the approach to modeling which incorporates a thorough understanding of the stress-dependent matrix cracking properties of the composite system.

  18. Soil Stress-Strain Behavior: Measurement, Modeling and Analysis

    Ling, Hoe I; Leshchinsky, Dov; Koseki, Junichi; A Collection of Papers of the Geotechnical Symposium in Rome


    This book is an outgrowth of the proceedings for the Geotechnical Symposium in Roma, which was held on March 16 and 17, 2006 in Rome, Italy. The Symposium was organized to celebrate the 60th birthday of Prof. Tatsuoka as well as honoring his research achievement. The publications are focused on the recent developments in the stress-strain behavior of geomaterials, with an emphasis on laboratory measurements, soil constitutive modeling and behavior of soil structures (such as reinforced soils, piles and slopes). The latest advancement in the field, such as the rate effect and dynamic behavior of both clay and sand, behavior of modified soils and soil mixtures, and soil liquefaction are addressed. A special keynote paper by Prof. Tatsuoka is included with three other keynote papers (presented by Prof. Lo Presti, Prof. Di Benedetto, and Prof. Shibuya).

  19. Experimental stress-strain analysis of tapered silica optical fibers with nanofiber waist

    Holleis, Sigrid; Wuttke, Christian; Schneeweiss, Philipp; Rauschenbeutel, Arno


    We experimentally determine tensile force-elongation diagrams of tapered optical fibers with a nanofiber waist. The tapered optical fibers are produced from standard silica optical fibers using a heat and pull process. Both, the force-elongation data and scanning electron microscope images of the rupture points indicate a brittle material. Despite the small waist radii of only a few hundred nanometers, our experimental data can be fully explained by a nonlinear stress-strain model that relies on material properties of macroscopic silica optical fibers. This is an important asset when it comes to designing miniaturized optical elements as one can rely on the well-founded material characteristics of standard optical fibers. Based on this understanding, we demonstrate a simple and non-destructive technique that allows us to determine the waist radius of the tapered optical fiber. We find excellent agreement with independent scanning electron microscope measurements of the waist radius.

  20. Study of the stress-strain state of compressed concrete elements with composite reinforcement

    Bondarenko Yurii


    Full Text Available The efficiency analysis of the application of glass composite reinforcement in compressed concrete elements as a load-carrying component has been performed. The results of experimental studies of the deformation-strength characteristics of this reinforcement on compression and compressed concrete cylinders reinforced by this reinforcement are presented. The results of tests and mechanisms of sample destruction have been analyzed. The numerical analysis of the stress-strain state has been performed for axial compression of concrete elements with glasscomposite reinforcement. The influence of the reinforcement percentage on the stressed state of a concrete compressed element with the noted reinforcement is estimated. On the basis of the obtained results, it is established that the glass-composite reinforcement has positive effect on the strength of the compressed concrete elements. That is, when calculating the load-bearing capacity of such structures, the function of composite reinforcement on compression should not be neglected.

  1. Spline Nonparametric Regression Analysis of Stress-Strain Curve of Confined Concrete

    Tavio Tavio


    Full Text Available Due to enormous uncertainties in confinement models associated with the maximum compressive strength and ductility of concrete confined by rectilinear ties, the implementation of spline nonparametric regression analysis is proposed herein as an alternative approach. The statistical evaluation is carried out based on 128 large-scale column specimens of either normal-or high-strength concrete tested under uniaxial compression. The main advantage of this kind of analysis is that it can be applied when the trend of relation between predictor and response variables are not obvious. The error in the analysis can, therefore, be minimized so that it does not depend on the assumption of a particular shape of the curve. This provides higher flexibility in the application. The results of the statistical analysis indicates that the stress-strain curves of confined concrete obtained from the spline nonparametric regression analysis proves to be in good agreement with the experimental curves available in literatures

  2. Evaluation of stress-strain for characterization of the rheological behavior of alginate and carrageenan gels

    E.J. Mammarella


    Full Text Available The stress-strain of samples deformed until failure and the relaxation response after 50% deformation of the initial height under constant stress were obtained. Uniaxial compression and stress-relaxation tests enabled satisfactory differentiation of the mechanical resistance of gels with different alginate and carrageenan concentrations. Higher values for initial force at the beginning of the relaxation test were associated with higher calcium uptake by the gels. An increment of failure stress during the uniaxial compression tests for higher concentration of calcium in the gel structure was also observed. The maximum amount of cation uptake was higher than the theoretical value for saturation of all the carboxylic groups available in alginate molecules due to structural rearrangements. Stress-relaxation tests indicated that the residual stress of the gel increased with kappa-carrageenan concentration.

  3. Analysis of Mechanical Stresses/Strains in Superconducting Wire

    Barry, Matthew; Chen, Jingping; Zhai, Yuhu


    The optimization of superconducting magnet performance and development of high-field superconducting magnets will greatly impact the next generation of fusion devices. A successful magnet development, however, relies deeply on the understanding of superconducting materials. Among the numerous factors that impact a superconductor's performance, mechanical stress is the most important because of the extreme operation temperature and large electromagnetic forces. In this study, mechanical theory is used to calculate the stresses/strains in typical superconducting strands, which consist of a stabilizer, a barrier, a matrix and superconducting filaments. Both thermal loads and mechanical loads are included in the analysis to simulate operation conditions. Because this model simulates the typical architecture of major superconducting materials, such as Nb3Sn, MgB2, Bi-2212 etc., it provides a good overall picture for us to understand the behavior of these superconductors in terms of thermal and mechanical loads. This work was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internship (SULI) program.

  4. Measurement of stress-strain behaviour of human hair fibres using optical techniques.

    Lee, J; Kwon, H J


    Many studies have presented stress-strain relationship of human hair, but most of them have been based on an engineering stress-strain curve, which is not a true representation of stress-strain behaviour. In this study, a more accurate 'true' stress-strain curve of human hair was determined by applying optical techniques to the images of the hair deformed under tension. This was achieved by applying digital image cross-correlation (DIC) to 10× magnified images of hair fibres taken under increasing tension to estimate the strain increments. True strain was calculated by summation of the strain increments according to the theoretical definition of 'true' strain. The variation in diameter with the increase in longitudinal elongation was also measured from the 40× magnified images to estimate the Poisson's ratio and true stress. By combining the true strain and the true stress, a true stress-strain curve could be determined, which demonstrated much higher stress values than the conventional engineering stress-strain curve at the same degree of deformation. Four regions were identified in the true stress-strain relationship and empirical constitutive equations were proposed for each region. Theoretical analysis on the necking condition using the constitutive equations provided the insight into the failure mechanism of human hair. This analysis indicated that local thinning caused by necking does not occur in the hair fibres, but, rather, relatively uniform deformation takes place until final failure (fracture) eventually occurs.

  5. Fractal approximation of the stress-strain curve of frozen soil

    令锋; 吴紫汪; 朱元林; 何春雄; 朱林楠


    A method to approach the stress-strain curve of frozen soil is presented based on the fact that the stressstrain curve of frozen soil has fractal property. First, a linear hyperbolic iterated function system (LHIFS) in which the perpendicular contraction factors are regarded as parameters is established using fractal geometry theories. Secondly, a method to calculate the best point which makes the attractor of the LHIFS an optimal approximation of the stress-strain curve of frozen soil is presented. Then, a method for calculating the fractal dimension of the stress-strain curve of frozen soil is obtained. Finally, a simple example is provided. The method presented in this paper provides a new method for simulating the stress-strain curve and calculating its fractal dimension of geomaterials that have the fractal feature by using computer.

  6. Parameter Optimisation of Stress-strain Constitutive Equations Using Genetic Algorithms

    Y. Y. Yang; M. Mahfouf; D.A.Linkens


    The accuracy of numerical simulations and many other material design calculations, such as the rolling force, rollingtorque, etc., depends on the description of stress-strain relationship of the deformed materials. One common methodof describing the stres

  7. Rate dependent rheological stress-strain behavior of porous nanocrystalline materials

    李慧; 周剑秋


    To completely understand the rate-dependent stress-strain behavior of the porous nanocrystalline materials,it is necessary to formulate a constitutive model that can reflect the complicated experimentally observed stress-strain relations of nanocrystalline materials.The nanocrystalline materials consisting grain interior and grain boundary are considered as viscoplastic and porous materials for the reasons that their mechanical deformation is commonly governed by both dislocation glide and diffusion,and pores commonly exist in the nanocrystalline materials.A constitutive law of the unified theory reflecting the stress-strain relations was established and verified by experimental data of bulk nanocrystalline Ni prepared by hydrogen direct current arc plasma evaporation method and hot compression.The effect of the evolution of porosity on stress-strain relations was taken into account to make that the predicted results can keep good agreements with the corresponding experimental results.


    木幡, 行宏; 三田地, 利之


    A series of drained stress probe test on saturated remoulded clay specimens consolidated and rebounded under anisotropic stress condition was performed to investigate the influence of anisotropic stress history and stress path on the stress-strain behavior of clay. Based on the test results, a new constitutive model was proposed which could successfully describe the stress-strain behavior of anisotropically lightly overconsolidated clay.

  9. True stress-strain curves of cold worked stainless steel over a large range of strains

    Kamaya, Masayuki; Kawakubo, Masahiro


    True stress-strain curves for cold worked stainless steel were obtained over a range of strains that included a large strain exceeding the strain for the tensile strength (post-necking strain). A specified testing method was used to obtain the stress-strain curves in air at room temperature. The testing method employed the digital image correlation (DIC) technique and iterative finite element analyses (FEA) and was referred to as IFD (Iteration FEA procedure based on DIC measurement) method. Although hourglass type specimens have been previously used for the IFD method, in this study, plate specimens with a parallel gage section were used to obtain accurate yield and tensile strengths together with the stress-strain curves. The stress-strain curves including the post-necking strain were successfully obtained by the IFD method, and it was shown that the stress-strain curves for different degrees of cold work collapsed onto a single curve when the offset strain was considered. It was also shown that the Swift type constitutive equation gave good regression for the true stress-strain curves including the post-necking strain regardless of the degree of cold work, although the Ramberg-Osgood type constitutive equation showed poor fit. In the regression for the Swift type constitutive equation, the constant for power law could be assumed to be nS = 0.5.

  10. Ultrasonic Measurement of Transient Change in Stress-Strain Property of Radial Arterial Wall Caused by Endothelium-Dependent Vasodilation

    Ikeshita, Kazuki; Hasegawa, Hideyuki; Kanai, Hiroshi


    The endothelial dysfunction is considered to be an initial step of atherosclerosis. Additionally, it was reported that the smooth muscle, which constructs the media of the artery, changes its characteristics owing to atherosclerosis. Therefore, it is essential to develop a method for assessing the regional endothelial function and mechanical property of the arterial wall. There is a conventional technique of measuring the transient change in the diameter of the brachial artery caused by flow-mediated dilation (FMD) after the release of avascularization. For more sensitive and regional evaluation, we developed a method of measuring the change in the elasticity of the radial artery due to FMD. In this study, the transient change in the mechanical property of the arterial wall was further revealed by measuring the stress-strain relationship during each heartbeat. The minute change in the thickness (strain) of the radial arterial wall during a cardiac cycle was measured by the phased tracking method, together with the waveform of blood pressure which was continuously measured with a sphygmometer at the radial artery. The transient change in stress-strain relationship during a cardiac cycle was obtained from the measured changes in wall thickness and blood pressure to show the transient change in instantaneous viscoelasticity. From the in vivo experimental results, the stress-strain relationship shows the hysteresis loop. The slope of the loop decreased owing to FMD, which shows that the elastic modulus decreased, and the increasing area of the loop depends on the ratio of the loss modulus (depends on viscosity) to the elastic modulus when the Voigt model is assumed. These results show a potential of the proposed method for the thorough analysis of the transient change in viscoelasticity due to FMD.

  11. Correction of the post -- necking true stress -- strain data using instrumented nanoindentation

    Romero Fonseca, Ivan Dario

    The study of large plastic deformations has been the focus of numerous studies particularly in the metal forming processes and fracture mechanics fields. A good understanding of the plastic flow properties of metallic alloys and the true stresses and true strains induced during plastic deformation is crucial to optimize the aforementioned processes, and to predict ductile failure in fracture mechanics analyzes. Knowledge of stresses and strains is extracted from the true stress-strain curve of the material from the uniaxial tensile test. In addition, stress triaxiality is manifested by the neck developed during the last stage of a tensile test performed on a ductile material. This necking phenomenon is the factor responsible for deviating from uniaxial state into a triaxial one, then, providing an inaccurate description of the material's behavior after the onset of necking. The research of this dissertation is aimed at the development of a correction method for the nonuniform plastic deformation (post-necking) portion of the true stress-strain curve. The correction proposed is based on the well-known relationship between hardness and flow (yield) stress, except that instrumented nanoindentation hardness is utilized rather than conventional macro or micro hardness. Three metals with different combinations of strain hardening behavior and crystal structure were subjected to quasi-static tensile tests: power-law strain hardening low carbon G10180 steel (BCC) and electrolytic tough pitch copper C11000 (FCC), and linear strain hardening austenitic stainless steel S30400 (FCC). Nanoindentation hardness values, measured on the broken tensile specimen, were converted into flow stress values by means of the constraint factor C from Tabor's, the representative plastic strainepsilonr and the post-test true plastic strains measured. Micro Vickers hardness testing was carried out on the sample as well. The constraint factors were 5.5, 4.5 and 4.5 and the representative plastic

  12. Seepage laws of two kinds of disastrous gas in complete stress-strain process of coal

    Cao Shugang; Guo Ping; Zhang Zunguo; Li Yi; Wang Yong


    The similarities and differences in seepage flow evolution laws of CH4 and CO2 during complete stressstrain process of samples were comparatively analyzed.The results show that the seepage flow evolution laws of CH4 and CO2 are extremely similar during the stress-strain process,showing that the characteristic first decreased and then increased.A mathematical model was also established according to the relationship of seepage velocity and axial strain.However,due to the strong adsorption ability of CO2,the coal samples generated a more serious “Klinkenberg effect” under the condition of CO2.Owing to this,the CO2 seepage flow resulted into occurrence of “stagnation” phenomenon during the late linear elastic stage Ⅱ.In the strain consolidation stage Ⅲ,the increment rate of CH4 seepage velocity was significantly greater than that of CO2.In the stress descent stage Ⅳ,when the axial load reached the peak pressure of coal,the increment rates of CH4 seepage velocity presented a turning point.But the changing rate of CO2 seepage velocity still remained slow and a turning point was presented at one time after the peak of the strain pressure,which showed an obvious feature of hysteresis.

  13. Eccentric Exercise: Physiological Characteristics and Acute Responses.

    Douglas, Jamie; Pearson, Simon; Ross, Angus; McGuigan, Mike


    An eccentric contraction involves the active lengthening of muscle under an external load. The molecular and neural mechanisms underpinning eccentric contractions differ from those of concentric and isometric contractions and remain less understood. A number of molecular theories have been put forth to explain the unexplained observations during eccentric contractions that deviate from the predictions of the established theories of muscle contraction. Postulated mechanisms include a strain-induced modulation of actin-myosin interactions at the level of the cross-bridge, the activation of the structural protein titin, and the winding of titin on actin. Accordingly, neural strategies controlling eccentric contractions also differ with a greater, and possibly distinct, cortical activation observed despite an apparently lower activation at the level of the motor unit. The characteristics of eccentric contractions are associated with several acute physiological responses to eccentrically-emphasised exercise. Differences in neuromuscular, metabolic, hormonal and anabolic signalling responses during, and following, an eccentric exercise bout have frequently been observed in comparison to concentric exercise. Subsequently, the high levels of muscular strain with such exercise can induce muscle damage which is rarely observed with other contraction types. The net result of these eccentric contraction characteristics and responses appears to be a novel adaptive signal within the neuromuscular system.

  14. Modeling of stress/strain behavior of fiber-reinforced ceramic matrix composites including stress redistribution

    Mital, Subodh K.; Murthy, Pappu L. N.; Chamis, Christos C.


    A computational simulation procedure is presented for nonlinear analyses which incorporates microstress redistribution due to progressive fracture in ceramic matrix composites. This procedure facilitates an accurate simulation of the stress-strain behavior of ceramic matrix composites up to failure. The nonlinearity in the material behavior is accounted for at the constituent (fiber/matrix/interphase) level. This computational procedure is a part of recent upgrades to CEMCAN (Ceramic Matrix Composite Analyzer) computer code. The fiber substructuring technique in CEMCAN is used to monitor the damage initiation and progression as the load increases. The room-temperature tensile stress-strain curves for SiC fiber reinforced reaction-bonded silicon nitride (RBSN) matrix unidirectional and angle-ply laminates are simulated and compared with experimentally observed stress-strain behavior. Comparison between the predicted stress/strain behavior and experimental stress/strain curves is good. Collectively the results demonstrate that CEMCAN computer code provides the user with an effective computational tool to simulate the behavior of ceramic matrix composites.

  15. Stress-Strain Relationship and Failure Criterion for Concrete after Freezing and Thawing Cycles

    Luo Xin; Wei Jun


    The research of the failure criterion and one-dimensional stress-strain relationship of deteriorated concrete were carried out.Based on the damage mechanics theory, the damage which reflects the alternation of internal state of material were introduced into the formula presented by Desayi and Krishman and the weighted twin-shear strength theory. As a nondestructive examination method in common use, the ultrasonic technique was adopted in the study, and the ultrasonic velocity was used to establish the damage variable. After that, the failure criterion and one-dimensional stress-strain relationship for deteriorated concrete were obtained.Eventually, tests were carried out to study the evolution laws on the damage. The results show that the more freezing and thawing cycles are, the more apparently the failure surface shrinks. Meanwhile, the comparison between theoretical data and experimental data verifies the rationality of the damage-based one-dimensional stress-strain relationship proposed.

  16. Summary report - development of laboratory tests and the stress- strain behaviour of Olkiluoto mica gneiss

    Hakala, M.; Heikkilae, E. [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Rock Engineering


    This work summarizes the project aimed at developing and qualifying a suitable combination of laboratory tests to establish a statistically reliable stress-strain behaviour of the main rock types at Posiva Oy`s detailed investigation sites for disposal of spent nuclear fuel. The work includes literature study of stress-strain behaviour of brittle rock, development and qualification of laboratory tests, suggested test procedures and interpretation methods and finally testing of Olkiluoto mica gneiss. The Olkiluoto study includes over 130 loading tests. Besides the commonly used laboratory tests, direct tensile tests, damage controlled tests and acoustic emission measurements were also carried out. (orig.) (54 refs.).

  17. Estimation of cyclic stress-strain curves for low-alloy steel from hardness

    R. Basan


    Full Text Available This article describes investigations into the existence of correlation between experimentally determined cyclic parameters and hardness of quenched and tempered representative low-alloy steel 42CrMo4. A good correlation was found to exist between cyclic strength coefficient K’ and Brinell hardness HB, but not between cyclic strain hardening exponent n‘ and hardness HB. Nevertheless, good agreement between calculated and experimental cyclic stress-strain curves shows that cyclic parameters i.e. cyclic stress-strain curves of the investigated steel can be successfully estimated from its hardness.

  18. Stress-strain distribution at the boundary area of coal seams containing nonuniformities

    Khaimova-Mal' kova, R.I.


    Discusses results of investigations carried out with the help of the finite element method in a 2 m thick coal seam at 400 m level, having varying properties and nonuniformities. Shows that considerable areas with horizontal deformation appear in soft coal which may result in vertical fissuring parallel to headings. States that presence of soft and hard inclusions in coal seams affect stress-strain state and stability of boundary areas and lead to spasmodic changes in stress-strain intensity which result in dynamic phenomena particularly in coal seams which are prone to sudden gas and coal outbursts. 3 refs.

  19. Microscopic study on stress-strain relation of granular materials

    LIU SiHong; YAO YangPing; SUN QiCheng; LI TieJun; LIU MinZhi


    A biaxial shearing test on granular materials is numerically simulated by distinct element method (DEM). The evolution of the microstructures of granular materials during isotropic compression and shearing is investigated, on which a yield function is derived. The new yield function has a similar form as the one used in the modified Cam-clay model and explains the yield characteristics of granular materials under the isotropic compression and shear process through the change of the contact distribution N(θ) defining the contacts at particle contact angle θ.

  20. Nondestructive and Localized Measurements of Stress-Strain Curves and Fracture Toughness of Ferritic Steels at Various Temperatures Using Innovative Stress-Strain Microprobe Technology. Final Report for Period 8/13/1996--06/16/1999

    Fahmy M. Haggag


    The results presented in this report demonstrate the capabilities of Advanced Technology Corporation's patented Portable/In Situ Stress-Strain Microprobe (TM) (SSM) System and its Automated Ball Indentation (ABI) test techniques to nondestructively measure the yield strength, the stress-strain curve, and the fracture toughness of ferritic steel samples and components in a reliable and accurate manner.

  1. Calculation of the stress-strain stiffness matrix for given strains in an inelastic material

    Friedrich, C.M.


    In the implicit method of non-linear analysis of stiffness matrices of finite elements, deflection fields and hence strains are assumed known at one stage of the calculations. A procedure is developed to calculate the stress-strain stiffness matrix from the strains without iteration of the stress components when the material is inelastic.

  2. Stress-strain-sorption behaviour of coal matrix material exposed to CO2

    Hol, S.


    Coal swells when it adsorbs carbon dioxide (CO2). The stress-strain behaviour associated with adsorption is of key importance in determining the feasibility of extracting methane (CH4) from coal via Enhanced Coalbed Methane production. ECBM involves injection of preferentially sorbing CO2 into the t



    A cyclic plasticity model is used into finite element (FE) method to obtain the details of elastic-plastic stress-strain in the bolts under cyclic axial loading. Two criteria in multiaxial fatigue are employed to predict fatigue lives of bolts. The predicted fatigue lives are in favorable agreement with the experimental results for machined bolts.

  4. Influence of the Geometry of Beveled Edges on the Stress-Strain State of Hydraulic Cylinders

    Buyalich, G. B.; Anuchin, A. V.; Serikov, K. P.


    The studies were carried out to determine the influence of forms obtained when preparing edges for welding a cylinder for hydraulic legs; the maximum stresses were defined at the location of weld roots, depending on variable parameters. The stress-strain states were calculated using finite element method.

  5. Compressive response of a glass-polymer system at various strain rates

    Fan, J.T.; Weerheijm, J.; Sluys, L.J.


    A glass-polymer system of a polyurethane elastomeric matrix with a single 3 mm-diameter glass particle was investigated using a split Hopkinson pressure bar (SHPB) setup for revealing the dynamic compressive mechanical response. This study produced the characteristics of the dynamic stress-strain re

  6. Prediction of stress-strain behavior of ceramic matrix composites using unit cell model

    Suzuki Takuya


    Full Text Available In this study, the elastic modulus and the stress-strain curve of ceramic matrix composites (CMCs were predicted by using the unit cell model that consists of fiber bundles and matrix. The unit cell model was developed based on the observation of cross sections of CMCs. The elastic modulus of CMCs was calculated from the results of finite element analysis using the developed model. The non-linear behavior of stress-strain curve of CMCs was also predicted by taking the degradation of the elastic modulus into consideration, where the degradation was related to the experimentally measured crack density in CMCs. The approach using the unit cell model was applied to two kinds of CMCs, and good agreement was obtained between the experimental and the calculated results.

  7. Stress/strain distributions for weld metal solidification crack in stainless steels


    This paper has simulated the driving force of solidification crack of stainless steels, that is, stress/strain field in the trail of molten pool. Firstly, the effect of the deformation in the molten pool was eliminated after the element rebirth method was adopted. Secondly, the influence of solidification shrinkage was taken into account by increasing thermal expansion coefficients of the steels at elevated temperatures. Finally, the stress/strain distributions of different conditions have been computed and analyzed. Furthermore, the driving force curves of the solidification crack of the steels have been obtained by converting strain-time curves into strain-temperature curves, which founds a basis for predicting welding solidification crack.

  8. Dynamic tensile testing for determining the stress-strain curve at different strain rate

    Mansilla, A; Regidor, A.; García, D.; Negro, A


    A detailed discussion of high strain-rate tensile testing is presented. A comparative analysis of different ways to measure stress and strain is made. The experimental stress-strain curves have been suitably interpreted to distinguish between the real behaviour of the material and the influence of the testing methodology itself. A special two sections flat specimen design was performed through FEA computer modelling. The mechanical properties as function of strain rate were experimentally obt...



    Problem statement. Despite the fact that rigid roads with asphalt concrete pavement widespread,their design and calculation provide for approximate data with some number of hidden factors. Thepresent paper proposes to use finite element method to model stress-strain state of rigid roads withasphalt concrete pavement.Results. The use of the finite element method enables one to construct the precise model ofstress-strain state of road pavement. The calculations performed on the basis of the mod...

  10. Stress, strain, and structural dynamics an interactive handbook of formulas, solutions, and Matlab toolboxes

    Yang, Bingen


    Stress, Strain, and Structural Dynamics is a comprehensive and definitive reference to statics and dynamics of solids and structures, including mechanics of materials, structural mechanics, elasticity, rigid-body dynamics, vibrations, structural dynamics, and structural controls. This text integrates the development of fundamental theories, formulas and mathematical models with user-friendly interactive computer programs, written in the powerful and popular MATLAB. This unique merger of technical referencing and interactive computing allows instant solution of a variety of engineering problems

  11. Effect of Engineering Character on Stress-Strain Relationship in Post-Peak Area

    TANG Lei; KE Min-yong; YAN Jian-hua


    Constitutive experiments are the base of all rock mechanics works. The effect of engineering character on constitutive law is a new problem of rock mechanics. The results of series specimens based on the uniaxial and plane strain compression experiments were presented and discussed. It is found that engineering or experiment character has obvious effects on stress-strain relationship and especially on mechanic parameters in post-peak area. And the law of size effect of softening materials was also discussed.

  12. Stress/strain Modelling of Casting Processes in the Framework of the Control-Volume Method

    Hattel, Jesper Henri; Thorborg, Jesper; Andersen, Søren


    Realistic computer simulations of casting processes call for the solution of both thermal, fluid-flow and stress/strain related problems. The multitude of the influencing parameters, and their non-linear, transient and temperature dependent nature, make the calculations complex. Therefore the need......, the present model is based on the mainly decoupled representation of the thermal, mechanical and microstructural processes. Examples of industrial applications, such as predicting residual deformations in castings and stress levels in die casting dies, are presented...

  13. In situ subsoil stress-strain behaviour in relation to soil precompression stress

    Keller, T; Arvidsson, J; Schjønning, Per;


    is assumed to be elastic and reversible as long as [sigma] laboratory. The data...... by stress-strain data measured in uniaxial compression tests, which likewise showed [Latin Small Letter Open E]res > 0 at [sigma] ... analyzed were from a large number of wheeling experiments carried out in Sweden and Denmark on soils with a wide range of texture. Contradicting the concept of precompression stress, we observed residual strain, [Latin Small Letter Open E]res, at [sigma

  14. Computer modeling of the stress-strain state of a linear friction welded disk

    V. Bychkov


    Full Text Available The paper is dedicated to design issues of tooling for linear friction welding (LFW machine. Computer model of a LFW machine was built. As a result of computer simulation, the stress-strain state of the machine and disk module for linear friction welding of aluminum alloy blisks also was obtained. On the basis of the results of computer simulation a module with a replaceable unit and a new variant fixing of disc in the module were designed.

  15. Evaluation of the stress-strain state of a one-dimensional heterogeneous porous structure

    Gerasimov, O.; Shigapova, F.; Konoplev, Yu; Sachenkov, O.


    The paper deals with the problem of determining the stress-strain state of the distal part of the pelvic girdle bones. The area was modeled using a rod loaded by a compressive force and was described by physical relations linking the stress-strain tensor through the elastic constants, the fabric tensor, and the solid volume fraction of the material. Taking into account the law of porosity variation, we considered the problem of evaluating the stress-strain state depending on the nature of the porous structure, and the relationship of the structure with mechanical macroparameters. In this work, we present the results of calculations for a single load, construct the diagrams for the components of the strain tensor, and carry out an assessment of deformations for various system parameters. To evaluate the macroparameters, we built the dependence of the Poisson ratio of the material on the rotation angle a and the pore ellipticity parameter λ. The sensitivity of the deformations to the elastic constants was also estimated.

  16. The stress-strain behavior of coronary stent struts is size dependent.

    Murphy, B P; Savage, P; McHugh, P E; Quinn, D F


    Coronary stents are used to re-establish the vascular lumen and flow conditions within the coronary arteries; the typical thickness of a stent strut is 100 microm, and average grain sizes of approximately 25 microm exist in stainless steel stents. The purpose of this study is to investigate the effect of strut size on the stress strain behavior of 316 L stainless steel. Other materials have shown a size dependence at the micron size scale; however, at present there are no studies that show a material property size dependence in coronary stents. Electropolished stainless steel stent struts within the size range of 60-500 microm were tensile tested. The results showed that within the size range of coronary stent struts a size dependent stress-strain relationship is required to describe the material. Finite element models of the final phase of fracture, i.e., void growth models, explained partially the reason for this size effect. This study demonstrated that a size based stress-strain relationship must be used to describe the tensile behavior material of 316 L stainless steel at the size scale of coronary stent struts.

  17. Modeling of Stress- Strain Curves of Drained Triaxial Test on Sand

    Awad A. Karni


    Full Text Available This paper presents a hyperbolic mathematical model to predict the complete stress-strain curve of drained triaxial tests on uniform dense sand. The model was formed in one equation with many parameters. The main parameters that are needed to run the model are the confining pressure, angle of friction and the relative density. The other parameters, initial and final slopes of the stress strain curve, the reference stress and the curve-shape parameter are determined as functions of the confining pressure, angle of friction and the relative density using best fitting curve technique from the experimental tests results. Drained triaxial tests were run on clean white uniform sand to utilize and verify this model. These tests were carried out at four levels of confining pressure of 100, 200, 300 and 400 kPa. This model was used to predict the stress-strain curves for drained triaxial tests on quartz sand at different relative density using the data of Kouner[1]. The model predictions were compared with the experimental results and showed good agreements of the predicted results with the experimental results at all levels of applied confining pressures and relative densities.

  18. Prediction of stress-strain state of municipal solid waste with application of soft soil creep model

    Ofrikhter Vadim Grigor'evich

    Full Text Available The deformation of municipal solid waste is a complex process caused by the nature of MSW, the properties of which differ from the properties of common soils. The mass of municipal solid waste shows the mixed behaviour partially similar to granular soils, and partially - to cohesive. So, one of mechanical characteristics of MSW is the cohesion typical to cohesive soils, but at the same time the filtration coefficient of MSW has an order of 1 m/day that is characteristic for granular soils. It has been established that MSW massif can be simulated like the soil reinforced by randomly oriented fibers. Today a significant amount of the verified and well proved software products are available for numerical modelling of soils. The majority of them use finite element method (FEM. The soft soil creep model (SSC-model seems to be the most suitable for modelling of municipal solid waste, as it allows estimating the development of settlements in time with separation of primary and secondary consolidation. Unlike the soft soil, one of the factors of secondary consolidation of MSW is biological degradation, the influence of which is possible to consider at the definition of the modified parameters essential for soft soil model. Application of soft soil creep model allows carrying out the calculation of stress-strain state of waste from the beginning of landfill filling up to any moment of time both during the period of operation and in postclosure period. The comparative calculation presented in the paper is executed in Plaxis software using the soft-soil creep model in contrast to the calculation using the composite model of MSW. All the characteristics for SSC-model were derived from the composite model. The comparative results demonstrate the advantage of SSC-model for prediction of the development of MSW stress-strain state. As far as after the completion of the biodegradation processes MSW behaviour is similar to cohesion-like soils, the demonstrated

  19. Stress-Strain Compression of AA6082-T6 Aluminum Alloy at Room Temperature

    Alexandre da Silva Scari


    Full Text Available Short cylindrical specimens made of AA6082-T6 aluminum alloy were studied experimentally (compression tests, analytically (normalized Cockcroft-Latham criteria—nCL, and numerically (finite element analysis—FEA. The mechanical properties were determined with the stress-strain curves by the Hollomon equation. The elastic modulus obtained experimentally differs from the real value, as expected, and it is also explained. Finite element (FE analysis was carried out with satisfactory correlation to the experimental results, as it differs about 1,5% from the damage analysis by the nCL concerning the experimental data obtained by compression tests.

  20. Stress-strain state and durability of mechanically inhomogeneous welds under low-cycle loading

    Brazenas, A.; Daunis, M.


    Relations are proposed for the determination of the stress-strain state, strength, and life of butt welds with mild and hard interlayers under cyclic elastoplastic tension-compression. The accumulation of cyclic and quasistatic damages is determined with allowance for the redistribution of the cyclic elastoplastic strains and hardness of the stress state due to changes in the cyclic properties of separate regions of welds. The theoretical distribution of cyclic strains and the durability of welds under cyclic elastoplastic loading are supported by experimental data

  1. Determination of stress-strain state of the wooden church log walls with software package

    Chulkova Anastasia


    Full Text Available The restoration of architectural monuments is going on all over the world today. The main aim of restoration is the renewal of stable functioning of building constructions in normal state. In this article, we have tried to figure out with special software the bearing capacity of log cabins of the Church of Transfiguration on Kizhi island. As shown in research results, determination of stress-strain stage with software package is necessary for the bearing capacity computation as well as field tests.

  2. Generalized Phenomenological Cyclic Stress-Strain-Strength Characterization of Granular Media.


    following special form of the general hypoelastic equation to model the behavior of granular media: dij = [a0 dem + a3 "pq d pq] 6ij + 1 dcij + C 2 dem...Phenomitno ogical I C.yclic Stress-Strain-Strength Characterization f Granular M~dia !RSO%.hL APT’.OR(S) M._McVay,_D._Seereeram,_P.__Linton andD... Granular Medi a, Vollow Cylinder. Cyclic Triaxial Test, Plasticity, Prediction Expanding Cavity LClic CTC rests ISTAAC? fCoom w mz_’-. ,f_.V,,A6’V "d

  3. Undirected learning styles and academic risk: Analysis of the impact of stress, strain and coping.

    Kimatian, Stephen; Lloyd, Sara; Berger, Jeffrey; Steiner, Lorraine; McKay, Robert; Schwengal, Deborah


    Learning style inventories used in conjunction with a measure of academic achievement consistently show an association of meaning directed learning patterns with academic success, but have failed to show a clear association of undirected learning styles with academic failure. Using survey methods with anesthesia residents, this study questioned whether additional assessment of factors related to stress, strain, and coping help to better define the association between undirected learning styles and academic risk. Pearson chi squared tests. 296 subjects were enrolled from eight institutions with 142 (48%) completing the study. American Board of Anesthesiologists In Training Examinations (ITE) percentiles (ITE%) were used as a measure of academic achievement. The Vermunt Inventory of Learning Styles (ILS) was used to identify four learning patterns and 20 strategies, and the Osipow Stress Inventory-Revised (OSI-R) was used as a measure of six scales of occupational stress, four of personal strain, and four coping resources. Two learning patterns had significant relationship with ITE scores. As seen in previous studies, Meaning Directed Learning was beneficial for academic achievement while Undirected Learning was the least beneficial. Higher scores on Meaning Directed Learning correlated positively with higher ITE scores while higher Undirected and lower Meaning Directed patterns related negatively to ITE%. OSI-R measures of stress, strain and coping indicated that residents with Undirected learning patterns had higher scores on three scales related to stress, and 4 related to strain, while displaying lower scores on two scales related to coping. Residents with higher Meaning Directed patterns scored lower on two scales of stress and two scales of strain, with higher scores on two scales for coping resources. Low Meaning Directed and high Undirected learning patterns correlated with lower ITE percentiles, higher scores for stress and strain, and lower coping resources




    Full Text Available Reactive Powder Concrete(RPC which is a new type of improved high strength concrete, is a recent development in concrete technology. Because the material is intrinsically strong in compression, the stress-strain behaviour of RPC under compression is of considerable interest in the design of RPC members and accurate prediction of their structural behaviour. An attempt has been made in the present study to determine the complete stress-strain curves from uniaxial compression tests. The effect of material composition on the stressstrain behaviour and the compression toughness are presented in the paper. The highest cylinder compressive strength of 171.3 MPa and elastic modulus of 44.8 GPa were recorded for 2% 13 mm Fibres. The optimum Fibre content was found to be 3% of 6mm or 2% of 13 mm. A new measure of compression toughness known as MTI (modified toughness index is proposed and it is found to range from 2.64 to 4.65 for RPC mixes.

  5. Predicting Nonlinear Behavior and Stress-Strain Relationship of Rectangular Confined Reinforced Concrete Columns with ANSYS

    A. Tata


    Full Text Available This paper presents a nonlinear finite element modeling and analysis of rectangular normal-strength reinforced concrete columns confined with transverse steel under axial compressive loading. In this study, the columns were modeled as discrete elements using ANSYS nonlinear finite element software. Concrete was modeled with 8-noded SOLID65 elements that can translate either in the x-, y-, or z-axis directions from ANSYS element library. Longitudinal and transverse steels were modeled as discrete elements using 3D-LINK8 bar elements available in the ANSYS element library. The nonlinear constitutive law of each material was also implemented in the model. The results indicate that the stress-strain relationships obtained from the analytical model using ANSYS are in good agreement with the experimental data. This has been confirmed with the insignificant difference between the analytical and experimental, i.e. 5.65 and 2.80 percent for the peak stress and the strain at the peak stress, respectively. The comparison shows that the ANSYS nonlinear finite element program is capable of modeling and predicting the actual nonlinear behavior of confined concrete column under axial loading. The actual stress-strain relationship, the strength gain and ductility improvement have also been confirmed to be satisfactorily.

  6. Stress-strain analysis of porous scaffolds made from titanium alloys synthesized via SLS method

    Shishkovsky, I.


    A layer-by-layer selective laser sintering (SLS) technology seems to be greatly promising for solving the plastic surgery problems, particularly those pertaining to the facial reconstruction. Made from titanium-based alloys (titanium or nitinol, i.e. NiTi-intermetallic phase), the porous scaffolds for cranioplasty are an efficient tool for rectifying the face defects and for the dental orthopedic surgery. The progress in the oral surgery and teeth implantation is caused by the problem of an osteointegration on the one hand, and by achievements of the implant synthesis techniques, on the other hand. An important problem thereby is a profound study of the stress-strain behavior of porous implants under the masticatory load or pressure. In the present study the ways for the optimization of the porous implant structural and strength properties as the function of the laser synthesis parameters are described. The finite element approach (ANSYS) was used here for a complex dowel description and numerical simulations. In order to evaluate the processes in the porous implant under the external loading, a CAD 3D model was built for different internal and external configurations of the implant and/or initial shape of powdered particles. The stress-strain dependences were calculated that displayed the irregularity of the stress distribution by the implant volume in the bone tissue. Most of the values are concentrated in places of object contact.

  7. Stress-strain relationship with soil structural parameters of collapse loess


    Through the tri-axial shearing tests of unsaturated intact loess and based on the concept of comprehensive soil structural potential,this paper reveals the changing laws of soil structural property under the triaxial stress conditions and establishes a mathematical expression equation of structural parameters,whereby reflecting the effects of unsaturated loess water content,stress and strain states,which is introduced into the shearing stress and shearing strain relation to obtain the structural stress-strain relation.The tests reveal that the loess dilatancy is of shearing contraction and shearing expansion,whereby indicating that there is a good linear relation between the stress ratio and shearing expansion strain ratio.The larger consolidation confining pressure is,the larger the stress of shearing contraction and expansion critical point is;and the larger water content is,the smaller the strain ratio of shearing contraction and expansion critical point is.Finally,the constitutive model is established to reflect the variation in loess structure,stressstrain softening and hardening,and shearing contraction and shearing expansion features.Through the comparative analysis,the stress-strain curves described by the constitutive relationship are found to be in good conformity with test results,whereby testing the rationality of the model in this paper.


    VÎLCU Adrian


    Full Text Available The paper analyses the tensile behavior of woven fabrics made from 45%Wool + 55% PES used for garments. Analysis of fabric behavior during wearing has shown that these are submitted to simple and repeated uni-axial or bi-axial tensile strains. The level of these strains is often within the elastic limit, rarely going over yielding. Therefore the designer must be able to evaluate the mechanical behavior of such fabrics in order to control the fabric behavior in the garment. This evaluation is carried out based on the tensile testing, using certain indexes specific to the stress-strain curve. The paper considers an experimental matrix based on woven fabrics of different yarn counts, different or equal yarn count for warp and weft systems and different structures. The fabrics were tested using a testing machine and the results were then compared in order to determine the fabrics’ tensile behavior and the factors of influence that affect it.From the point of view of tensile testing, the woven materials having twill weave are preferable because this type of structure is characterized by higher durability and better yarn stability in the fabric. In practice, the woven material must exhibit an optimum behavior to repeated strains, flexions and abrasions during wearing process. The analysis of fabrics tensile properties studied by investigation of stress-strain diagrams reveals that the main factors influencing the tensile strength are: yarns fineness, technological density of those two systems of yarns and the weaving type.

  9. Stress-strain curves for different loading paths and yield loci of aluminum alloy sheets

    WU Xiang-dong; WAN Min; HAN Fei; WANG Hai-bo


    To carry out biaxial tensile test in sheet metal, the biaxial tensile testing system was established. True stress-true strain curves of three kinds of aluminum alloy sheets for loading ratios of 4:1, 4:2, 4:3, 4:4, 3:4, 2:4 and 1:4 were obtained by conducting biaxial tensile test in the established testing systems. It shows that the loading path has a significant influence on the stress-strain curves and as the loading ratio increases from 4:1 to 4:4, the stress-strain curve becomes higher and n-value becomes larger.Experimental yield points for three aluminum alloy sheets from 0.2% to 2% plastic strain were determined based on the equivalent plastic work. And the geometry of the experimental yield loci were compared with the yield loci calculated from several existing yield criteria. The analytical result shows that the Barlat89 and Hosford yield criterion describe the general trends of the experimental yield loci of aluminum alloy sheets well, whereas the Mises yield criterion overestimates the yield stress in all the contours.

  10. The Effect of Microstructure on Stress-Strain Behaviour and Susceptibility to Cracking of Pipeline Steels

    A. Mustapha


    Full Text Available The effect of microstructure on the stress-strain behaviour of pipeline steels was studied. Slow strain rate (2×10-6 s-1 tests were conducted on grade X65 and X100 steels in silicone oil and hydrogen carbonate/carbonate solution. The as-received grade X100 steel at 75°C showed serrated stress-strain curves. The magnitude of the serrations depended upon the strain rate and test temperature. Annealing at 600°C or above removes the serrations, but this increased the susceptibility to transgranular cracking in hydrogen carbonate/carbonate solution at potentials below −800 mV (sce. The removal and reformation of banding in pipeline steels were also studied. Ferrite/pearlite becomes aligned during the hot rolling stage of pipe manufacture and causes directionality in crack propagation and mechanical properties. Heat treatments were carried out which show that banding in grade X65 and X100 can be removed above 900°C. This depends on homogenisation of carbon which also depends on temperature, time, and cooling rate.



    A new algorithm of structure random response numerical characteristics, named as matrix algebra algorithm of structure analysis is presented.Using the algorithm, structure random response numerical characteristics can easily be got by directly solving linear matrix equations rather than structure motion differential equations.Moreover, in order to solve the corresponding linear matrix equations, the numerical integration fast algorithm is presented.Then according to the results, dynamic design and life-span estimation can be done.Besides, the new algorithm can solve non-proportion damp structure response.

  12. Research on Frequency Response Characteristics of Rolling Mill

    CaiZhengguo; ZhangKenan


    The measurement method of frequency response characteristics for rolling mill is established by imposing different signal excitation on PID input of rolling mill under the different rolling conditions. The analysis results declare that sweep sine signal was relative efficient to evaluation for the frequency response character of hydraulic system. The practical application shows that the corresponding relationship between the parameters and the frequency response range of the rolling mill is helpful for parameters verification of process control and condition monitoring of hydraulic system.

  13. Cyclic stress-strain behavior of polymeric nonwoven structures for the use as artificial leaflet material for transcatheter heart valve prostheses

    Arbeiter Daniela


    Full Text Available Xenogenic leaflet material, bovine and porcine pericardium, is widely used for the fabrication of surgically implanted and transcatheter heart valve prostheses. As a biological material, long term durability of pericardium is limited due to calcification, degeneration and homogeneity. Therefore, polymeric materials represent a promising approach for a next generation of artificial heart valve leaflets with improved durability. Within the current study we analyzed the mechanical performance of polymeric structures based on elastomeric materials. Polymeric cast films were prepared and nonwovens were manufactured in an electrospinning process. Analysis of cyclic stress-strain behavior was performed, using a universal testing machine. The uniaxial cyclic tensile experiments of the elastomeric samples yielded a non-linear elastic response due to viscoelastic behavior with hysteresis. Equilibrium of stress-strain curves was found after a specific number of cycles, for cast films and nonwovens, respectively. In conclusion, preconditioning was found obligatory for the evaluation of the mechanical performance of polymeric materials for the use as artificial leaflet material for heart valve prostheses.

  14. Stress-strain relations for swelling anhydritic clay rocks – A review

    Breuer, Simon; Blum, Philipp; Butscher, Christoph


    The swelling of clay-sulfate rocks is a major threat in tunnel engineering, causing serious damage to tunnels and producing high additional costs during tunnel construction and operation. The swelling leads to geomechanical processes that may result in heave of the tunnel invert, destruction of the lining or uplift of the entire tunnel section. Heave-pressure-time relations are needed when predictions should be made about the mechanical behavior of swelling rock. For pure clay rocks, there is a linear relation between the swelling heave (strain) and the logarithm of pressure (Grob 1972). A generally accepted relation for clay-sulfate rocks, however, is still lacking to date. Therefore, finding appropriate and sustainable counter measures for an actual tunneling project affected by swelling remains extremely difficult. Grob (1972) proposed the linear relation between heave and the logarithm of pressure ("semi-logarithmic swelling law") not only for clay rocks, but also for clay-sulfate rocks. Pimentel (2007), however, presented laboratory experiments indicating that the semi-logarithmic swelling law may be inadequate for describing the swelling of clay-sulfate rocks. The laboratory tests revealed three different stages in the swelling process, including minimal deformation and prevented gypsum crystallization at high pressures (> 6 MPa); large deformation and gypsum crystallization at medium pressures; and only small deformation, possibly along with gypsum dissolution, at low pressures (water inflow into the rock, which cannot be reflected by general strain-stress relations. The present study critically reviews stress-strain relations for swelling anhydritic clay rocks proposed by various authors. Subsequently, published laboratory data from oedometric swelling tests are presented that may confirm the proposed stress-strain relationships. Finally, these data are re-examined by comparing each of the proposed relations with the same data set. Based on these results, a

  15. A computer program for plotting stress-strain data from compression, tension, and torsion tests of materials

    Greenbaum, A.; Baker, D. J.; Davis, J. G., Jr.


    A computer program for plotting stress-strain curves obtained from compression and tension tests on rectangular (flat) specimens and circular-cross-section specimens (rods and tubes) and both stress-strain and torque-twist curves obtained from torsion tests on tubes is presented in detail. The program is written in FORTRAN 4 language for the Control Data 6000 series digital computer with the SCOPE 3.0 operating system and requires approximately 110000 octal locations of core storage. The program has the capability of plotting individual strain-gage outputs and/or the average output of several strain gages and the capability of computing the slope of a straight line which provides a least-squares fit to a specified section of the plotted curve. In addition, the program can compute the slope of the stress-strain curve at any point along the curve. The computer program input and output for three sample problems are presented.

  16. Dynamic damage and stress-strain relations of ultra-high performance cementitious composites subjected to repeated impact


    Ultra-high performance cementitious composites (UHPCC) were prepared by replacing 60% of cement with ultra-fine industrial waste powders.The dynamic damage and compressive stress-strain relations of UHPCC were studied using split Hopkinson pressure bar (SHPB).The damage of UHPCC subjected to repeated impact was measured by the ultrasonic pulse velocity method.Results show that the dynamic damage of UHPCC increases linearly with impact times and the abilities of repeated impact resistance of UHPCC are improved with increasing fiber volume fraction.The stress waves on impact were recorded and the average stress,strain and strain rate of UHPCC were calculated based on the wave propagation theory.The effects of strain rate,fibers volume fraction and impact times on the stress-strain relations of UHPCC were studied.Results show that the peak stress and elastic modulus decrease while the strain rate and peak strain increase gradually with increasing impact times.


    顾明; 刘慈军; 徐幼麟; 项海帆


    A wind tunnel investigation of response characteristics of cables with artificial rivulet is presented.A series of cable section models of different mass and stiffness and damping ratio were designed with artificial rivulet.They were tested in smooth flow under different wind speed and yaw angle and for different position of artificial rivulet.The measured response of cable models was then analyzed and compared with the experimental results obtained by other researchers and the existing theories for wind-induced cable vibration.The results show that the measured response of horizontal cable models with artificial rivulet could be well predicted by Den Hartog' s galloping theory when wind is normal to the cable axis.For the wind with certain yaw angles, the cable models with artificial rivulet exhibit velocity-restricted response characteristics.

  18. Superelastic stress-strain behavior in ferrogels of different types of magneto-elastic coupling

    Cremer, Peet; Menzel, Andreas M


    Colloidal magnetic particles embedded in an elastic polymer matrix constitute a smart material called ferrogel. It responds to an applied external magnetic field by changes in elastic properties, which can be exploited for various applications like dampers, vibration absorbers, or actuators. Under appropriate conditions, the stress-strain behavior of a ferrogel can display a fascinating feature: superelasticity, the capability to reversibly deform by a huge amount while barely altering the applied load. In a previous work, using numerical simulations, we investigated this behavior assuming that the magnetic moments carried by the embedded particles can freely reorient to minimize their magnetic interaction energy. Here, we extend the analysis to ferrogels where restoring torques by the surrounding matrix hinder rotations towards a magnetically favored configuration. For example, the particles can be chemically cross-linked into the polymer matrix and the magnetic moments can be fixed to the particle axes. We ...

  19. Simulation of Stress-Strain behavior for one-dimensional aluminum samples subjected to high temperature

    Bellini, Anna; Thorborg, Jesper; Hattel, Jesper


    In order to satisfy the growing need in high quality aluminum cast parts of the automobile industries, in the last decades the foundries have been showing an increasing interest in the implementation of numerical simulations as part of their process design. As a consequence, it is possible to find...... the analysis of the next phases, such as heat treatment and life prediction of the cast parts. Because of the lack of numerical program tools capable of predicting the stress-strain behavior of aluminum parts subjected to high temperature, it is indeed normally assumed that at the end of the thermal treatment...... in literature several programs capable of simulating the entire casting process, i.e. filling, solidification, as well as developed thermomechanical stresses. However, it is common practice in the foundry industry that the results obtained by the simulation of the cast process are "forgotten" during...

  20. Stress-strain curves of aluminum nanowires: Fluctuations in the plastic regime and absence of hardening

    Pastor-Abia, L.; Caturla, M. J.; Sanfabián, E.; Chiappe, G.; Louis, E.


    The engineering stress-strain curves of aluminum nanowires have been investigated by means of molecular dynamics. Nanowires were stretched at constant strain rate and at a temperature of 4.2 K. Atoms at fixed positions with velocities randomly distributed according to Maxwell distribution were taken as initial conditions. Averaging over at least 1500 realizations allows the conclusion that, beyond the yield point, the system does not harden, in line with experimental results for larger nanowires of gold measured at room temperature. Fluctuations of the heat exchanged in the nonlinear regime have been investigated by analyzing around 1.5 million data. The results indicate the presence of non-Gaussian tails in the heat probability distribution.

  1. Morphology and stress-strain properties along the small intestine in the rat.

    Dou, Yanling; Zhao, Jingbo; Gregersen, Hans


    The stress-strain relationship is determined by the inherent mechanical properties of the intestinal wall, the geometric configurations, the loading conditions and the zero-stress state of the segment. The purpose of this project was to provide morphometric and biomechanical data for rat duodenum, jejunum and ileum. The circumferential strains were referenced to the zero-stress state. Large morphometric variations were found along the small intestine with an increase in the outer circumferential length and luminal area and a decrease in wall thickness in distal direction. The serosal residual strain was tensile and decreased in distal direction (P small intestine. The zero-stress state must be considered in future biomechanical studies in the gastrointestinal tract.

  2. A novel evolutionary algorithm applied to algebraic modifications of the RANS stress-strain relationship

    Weatheritt, Jack; Sandberg, Richard


    This paper presents a novel and promising approach to turbulence model formulation, rather than putting forward a particular new model. Evolutionary computation has brought symbolic regression of scalar fields into the domain of algorithms and this paper describes a novel expansion of Gene Expression Programming for the purpose of tensor modeling. By utilizing high-fidelity data and uncertainty measures, mathematical models for tensors are created. The philosophy behind the framework is to give freedom to the algorithm to produce a constraint-free model; its own functional form that was not previously imposed. Turbulence modeling is the target application, specifically the improvement of separated flow prediction. Models are created by considering the anisotropy of the turbulent stress tensor and formulating non-linear constitutive stress-strain relationships. A previously unseen flow field is computed and compared to the baseline linear model and an established non-linear model of comparable complexity. The results are highly encouraging.

  3. The compression stress-strain behavior of Sn-Ag-Cu solder

    Vianco, Paul T.; Rejent, Jerome A.; Martin, Joseph J.


    The yield-stress behavior was investigated for the 95.5Sn-4.3Ag-0.2Cu (wt.%), 95.5Sn-3.9Ag-0.6Cu, and 95.5Sn-3.8Ag-0.7Cu ternary lead-free solders using the compression stress-strain test technique. Cylindrical specimens were evaluated in the as-cast or aged (125°C, 24 h) condition. The tests were performed at -25°C, 25°C, 75°C, 125°C, and 160°C using strain rates of 4.2×10-5s-1 or 8.3×10-4s-1. Specially designed Sn-Ag-0.6Cu samples were fabricated to compare the yield stress of the dendritic microstructure versus that of the equiaxed microstructure that occurs in this alloy.

  4. Modelling of Stress-Strain Relationship of Toyoura Sand in Large Cyclic Torsional Loading

    Hong Nam, Nguyen; Koseki, Junichi

    The relationships between normalized shear stress and plastic shear strain of air-dried, dense Toyoura sand measured during large amplitude cyclic torsional loading with using local strain measurement could be well simulated numerically by the proportional rule combined with the drag rule. The proportional rule is an extended version of the Masing's second rule and can account for unsymmetrical stress strain behavior about neutral axis. The drag rule can account for strain hardening in cyclic loadings. Use of the newly proposed hypoelastic model for the quasi-elastic properties, the backbone curve using general hyperbolic equation or newly proposed lognormal equation for monotonic loading behavior, and the combination of the proportional rule and the drag rule for cyclic loading behavior would enable more precise simulation of deformation properties than before.


    Mirsayapov Ilshat Talgatovich


    Full Text Available The author offer transforming the diagram of ideal elastic-plastic deformations for the description of the stress-strain state of embedment of reinforcement behind a critical inclined crack at repeatedly repeating loadings. The endurance limit of the adhesion between concrete and reinforcement and its corresponding displacements in case of repeated loadings are accepted as the main indicators. This adhesion law is the most appropriate for the description of physical and mechanical phenomena in the contact zone in case of cyclic loading, because it simply and reliably describes the adhesion mechanism and the nature of the deformation, and greatly simplifies the endurance calculations compared to the standard adhesion law. On the basis of this diagram the author obtained the equations for the description of the distribution of pressures and displacements after cyclic loading with account for the development of deformations of cyclic creep of the concrete under the studs of reinforcement.

  6. SC response characteristics of two kinds of coagulant

    杨万东; 宋爽; 史惠祥


    Automatic coagulant dosage control with streaming current (SC) technique is introduced in this paper. Aluminum and ferric coagulants are widely used in surface water treatment. The SC response characteristics of P-AlCl3 aluminum coagulant and P-FeCl3 ferric coagulant were investigated in this work. Bench-scale water treatment results were obtained from jar tests including rapid mixing, flocculation and undisturbed sedimentation. Results showed that aluminum coagulant is more sensitive than ferric coagulant to SC response.

  7. SC response characteristics of two kinds of coagulant

    杨万东; 宋爽; 史惠祥


    Automatic coagulant dosage control with streaming current (SC) technique is in troduced inthis paper. Aluminum and ferric coagulants are widely used in surface water treatment. The SC response characteristics of P-AiCI3 aluminum coagulant and P-FeCI3 ferric coagulant were investigated in this work. Bench-scale water treatment results were obtained from jar tests including rapid mixing,flocculation and undisturbed sedimentation. Results showed that aluminum coagulant is more sensitive than ferric coagulant to SC response.

  8. Longitudinal residual strain and stress-strain relationship in rat small intestine

    Fan Yanhua


    Full Text Available Abstract Background To obtain a more detailed description of the stress-free state of the intestinal wall, longitudinal residual strain measurements are needed. Furthermore, data on longitudinal stress-strain relations in visceral organs are scarce. The present study aims to investigate the longitudinal residual strain and the longitudinal stress-strain relationship in the rat small intestine. Methods The longitudinal zero-stress state was obtained by cutting tissue strips parallel to the longitudinal axis of the intestine. The longitudinal residual stress was characterized by a bending angle (unit: degrees per unit length and positive when bending outwards. Residual strain was computed from the change in dimensions between the zero-stress state and the no-load state. Longitudinal stresses and strains were computed from stretch experiments in the distal ileum at luminal pressures ranging from 0–4 cmH2O. Results Large morphometric variations were found between the duodenum and ileum with the largest wall thickness and wall area in the duodenum and the largest inner circumference and luminal area in the distal ileum (p 0.5. The longitudinal residual strain was tensile at the serosal surface and compressive at the mucosal surface. Hence, the neutral axis was approximately in the mid-wall. The longitudinal residual strain and the bending angle was not uniform around the intestinal circumference and had the highest values on the mesenteric sides (p α constant increased with the pressure, indicating the intestinal wall became stiffer in longitudinal direction when pressurized. Conclusion Large longitudinal residual strains reside in the small intestine and showed circumferential variation. This indicates that the tissue is not uniform and cannot be treated as a homogenous material. The longitudinal stiffness of the intestinal wall increased with luminal pressure. Longitudinal residual strains must be taken into account in studies of

  9. Experimental determination of the micro-scale strength and stress-strain relation of an epoxy resin

    Zike, Sanita; Sørensen, Bent F.; Mikkelsen, Lars Pilgaard


    An approach is developed for determining the stress-strain law and a failure stress appropriate for micro-mechanical models of polymer materials. Double cantilever beam test specimens, made of an epoxy polymer with notches having finite root radius, were subjected to pure bending moments in an en......An approach is developed for determining the stress-strain law and a failure stress appropriate for micro-mechanical models of polymer materials. Double cantilever beam test specimens, made of an epoxy polymer with notches having finite root radius, were subjected to pure bending moments...

  10. Numerical calculation of the stress-strain state of non-rigid pavements, renovated by cold recycling technology

    Світлана Михайлівна Талах


    Full Text Available The problem of improving the scientific basis to determine the stress-strain state of non-rigid pavements, renovated by cold recycling technology, is considered. The results of numerical calculation of stress-strain state of non-rigid pavements in the section of road Kyv-Kovel (297 + 700 km - 302 + 400 km are given using automated calculation software complex of thin-walled spatial structures (KARTPK. The real state of the road section through 8.5 years after the renovation is analyzed

  11. Seismic response to stress-strain fields in the lithosphere of Sicily

    R. Scarpa


    Full Text Available Earthquake locations and fault-plane solutions are investigated in Sicily and the surrounding areas, by using local network data for the period 1988-1995, and a recently proposed 3D model of the local crustal structure. The results were used for local-to-regional scale stress inversion and strain tensor computations, after integration by a set of selected focal mechanisms taken from the literature. The area under study appears to be affected by heterogeneity of seismic deformation and the stress field. The contraction-to-extension transition from west to east on a regional scale can find a reasonable explanation in the framework of current geodynamic models, such as those assuming the activity of two main tectonic sources in the South Italy region, e.g., the Africa-Europe north-south slow convergence and the faster eastward roll-back of a westward-dipping Ionian subducting slab (Cinque al., 1993. The analysis of low-magnitude (2.5-4.0 earthquakes permitted us to perform an investigation of local-scale strain heterogeneities in this region and to evidence notable changes in the deformation style when processes at different scales are considered.

  12. The experimental investigation of bounce characteristics of ACV responsive skirt

    Zhou, W. L.; Ma, T.

    This paper presents some experimental results on the bounce characteristics of the bag-finger responsive skirt and on skirt frequency response under cushion pressure excitation obtained in a large-scale box facility. The influence of some parameters on the amplitude and frequency of the skirt bounce motion and the amplitude of the cushion pressure oscillation were explored, and the corresponding bounce boundary curves are given. Some interesting nonlinear phenomena related to the skirt instability in the time domain response are presented. The mechanism for skirt bounce and the important parameters affecting skirt dynamic stability are examined, and some means for eliminating skirt bounce are introduced.

  13. Nonlinear rheology of glass-forming colloidal dispersions: transient stress-strain relations from anisotropic mode coupling theory and thermosensitive microgels

    Amann, C. P.; Siebenbürger, M.; Ballauff, M.; Fuchs, M.


    Transient stress-strain relations close to the colloidal glass transition are obtained within the integration through transients framework generalizing mode coupling theory to flow driven systems. Results from large-scale numerical calculations are quantitatively compared to experiments on thermosensitive microgels, which reveals that theory captures the magnitudes of stresses semi-quantitatively even in the nonlinear regime, but overestimates the characteristic strain where plastic events set in. The former conclusion can also be drawn from flow curves, while the latter conclusion is supported by a comparison to single particle motion measured by confocal microscopy. The qualitative picture, as previously obtained from simplifications of the theory in schematic models, is recovered by the quantitative solutions of the theory for Brownian hard spheres.

  14. Nonlinear rheology of glass-forming colloidal dispersions: transient stress-strain relations from anisotropic mode coupling theory and thermosensitive microgels.

    Amann, C M; Siebenbürger, M; Ballauff, M; Fuchs, M


    Transient stress-strain relations close to the colloidal glass transition are obtained within the integration through transients framework generalizing mode coupling theory to flow driven systems. Results from large-scale numerical calculations are quantitatively compared to experiments on thermosensitive microgels, which reveals that theory captures the magnitudes of stresses semi-quantitatively even in the nonlinear regime, but overestimates the characteristic strain where plastic events set in. The former conclusion can also be drawn from flow curves, while the latter conclusion is supported by a comparison to single particle motion measured by confocal microscopy. The qualitative picture, as previously obtained from simplifications of the theory in schematic models, is recovered by the quantitative solutions of the theory for Brownian hard spheres.

  15. Stress-strain state near mine workings in anisotropic rock masses under the action of discontinuous waves

    Baranowski, Z.; Lugovoi, P. Z.


    The ray-path method is used to analyze the stress-strain state near mine workings acted upon by discontinuous waves. A dynamic failure criterion is proposed for analyzing the stability of mine workings. The efficiency of the approach is demonstrated with a specific example

  16. Permeability of coal to CH4 under fixed volume boundary conditions: the effect of stress-strain-sorption behaviour

    Liu, Jinfeng; Fokker, Peter; Spiers, Christopher


    Permeability evolution in coal reservoirs during CO2-Enhanced Coalbed Methane (ECBM) production is strongly influenced by swelling/shrinkage effects related to sorption and desorption of CO2 and CH4, respectively. Numerous permeability models, coupling the swelling response of coal to gas sorption, have been developed to predict in-situ coal seam permeability evolution during (E)CBM. However, experimental studies, aimed at testing such models, have mainly focused on the permeability changes occurring under constant lateral stress conditions, which are inconsistent with the in-situ boundary condition of (near) zero lateral strain. We performed CH4 permeability measurements, using the steady-state method, on a cylindrical sample of high volatile bituminous coal (25mm in diameter), under (near) fixed volume versus fixed stress conditions. The sample possessed a clearly visible cleat system. To isolate the effect of sorption on permeability evolution, helium (non-sorbing gas) was used as a control fluid. The bulk sample permeability to helium, under stress control conditions, changed from 4.07×10-17to 7.5×10-18m2, when the effective stress increased from 19.1 to 35.2MPa. Sorption of CH4 at a constant pressure of 10MPa, under fixed volume boundary conditions, resulted in a confining pressure increase from a poroelastically supported value of 29.3MPa to a near-equilibrium value of 38.6MPa over 171 hours. This is caused by the combined effect of the sorption-induced swelling and the self-compression of the sample. The concentration of CH4 adsorbed by the sample was 0.113 mmol/gcoal. During the adsorption process, the permeability to CH4 also decreased from 2.38×10-17 to 4.91×10-18m2, proving a strong influence of stress-strain-sorption behavior (c.f. Hol et al., 2012) on fracture permeability evolution. The CH4 permeability subsequently measured under stress controlled conditions varied from 1.37×10-17 to 4.33×10-18m2, for same change in confining pressure, i.e. 28

  17. Analysis of stress-strain state on top of a rectangular wedge

    Frishter Lyudmila Yur'evna


    Full Text Available Modeling singular solutions of the elasticity theory problems, which are determined by geometric factor - bird's mouth of the edge, make it necessary to analyze the solutions with some peculiarity, which are obtained experimentally with the help of photoelasticity method. In this article the peculiar stress-strain state is analyzed on the example of the known experimental solutions for a wedge under a concentrated force obtained by M. Frocht. Solution analysis for a wedge with a power-type peculiarity obtained experimentally by photoelasticity method, helps to detach a singular solution field, where fringe contour is not visible. Due to idealization of the boundary shape and loading technique, infinitely large stresses arise, which are obtained as a singular solution of the boundary problem in a planar domain. Comparison of theoretical and experimental solutions obtained for a wedge shows areas of overlap and areas of significant and insignificant differences as a result of the inability to experimentally apply the force to a single point.

  18. Problematics of stress-strain state research in units of metal structures

    Morozova Dina Vol'demarovna


    Full Text Available The article describes the experimental methods of determining stress-strain state of elements and structures with a brief description of the essence of each method. The authors focus mostly on polarization-optical method for determining stresses in the translucent optical sensing models made of epoxy resins. Physical component of the method is described in the article and a simple diagram of a circular polariscope is presented, as well as an example of the resulting interference pattern in illuminated monochromatic light. A polariscope, in its most general definition, consists of two polarizers. The polarizers sandwich a material or object of interest, and allows one to view the changes of the polarity of light passing through the material or object. Since we are unable to perceive the polarity of light with the naked eye, we are forced to use polariscopes to view the changes in polarity caused by the temporary birefringence of our photoelastic materials. A polariscope is constructed of two polarizers, each set perpendicular to the path of light transmitted through the setup. The first polarizer is called the "polarizer", and the second polarizer is called the "analyzer". The method how the polarizer works is quite simple: unpolarized light enters the polariscope through the polarizer, which allows through only the light of its orientation. This light then passes through the material under observation, and experiences some change in polarity. Finally, this light reaches the analyzer, which, like the polarizer, only lets the light of its orientation through.

  19. The stability of thermodynamically metastable phases in a Zr-Sn-Nb-Mo alloy: Effects of alloying elements, morphology and applied stress/strain

    Yu, Hongbing; Yao, Zhongwen; Daymond, Mark R.


    In this paper, a dual phase Zr-Sn-Nb-Mb alloy was studied with TEM after thermal treatment and high-temperature tensile deformation. Plate and pressure tube material, manufactured through different processing routes, were used in this study. The overall average concentrations of Mo and Nb in the β phase are higher in the pressure tube than in the plate. It was revealed that these concentrations have significant effects on the subsequent stability of the β and ω phases as well as on the precipitation behavior of the α phase from the β phase. That is, the higher the concentrations, the more stable the β and ω phases are, and hence there is a reduced tendency for precipitation of α phase. Aging treatments cause the transformation of athermal ω to isothermal ω, as expected. The most striking finding is the product of the decomposition of the isothermal ω particles during aging treatment is determined as not being α phase, even though the structure of it is, as-yet, not fully determined. The non-uniform morphology of the β grains in the plate material provides us a unique opportunity to investigate the effects of morphology on the aging response of the β phase. It was found that thin β filaments suppress the precipitation of isothermal ω particles but enhance the precipitation of α phase at α/β interfaces. The effect of the Burgers orientation relationship between α and β grains on the precipitation of the α phase at the α/β interface is discussed. Applied high-temperature stress/strain has been found to enhance the decomposition of isothermal ω phase but suppress α precipitation inside the β grains. The suppression of α precipitation by applied stress/strain is discussed in terms of the ω assisted α precipitation. Implications of these findings for the in-service application of the alloy are discussed.

  20. Impact of rockfill deformation on stress-strain state on dam reinforced concrete face

    Sainov Mikhail Petrovich


    Full Text Available The author considered the results of the numerical studies of stress-strain state of a 100 m high rockfill dam with a reinforced concrete face. In the analysis, the dam construction sequence and loads applied to it were considered; it was assumed that the reinforced concrete face was constructed after filling the dam. The calculations were carried out in the elastic formulation at various moduli of deformation and Poisson’s ratio. It was revealed that at rockfill settlement under the action of hydrostatic pressure the reinforced concrete face not only bends but also is subject to longitudinal force. The development of these forces is connected not only with rockfill shear deformation in horizontal direction. Depending on the value of rockfill Poisson’s ratio these longitudinal forces may be both compressive and tensile. At the Poisson’s ratio exceeding 0.25 the longitudinal forces are tensile, and when it is equal to 0.2 - they are compressive. Evidently these particular longitudinal forces are the course of crack formation in reinforced concrete faces of a number of constructed dams. The indirect confirmation of the development of tensile forces on the face is the fact that actually in all the dams with reinforced concrete face opening of perimeter joint was observed. Thus, in order to provide the strength of reinforced concrete it is important to increase rockfill shear modulus. Only the decrease of stone compressibility (i.e. increase of linear deformation modulus E will slightly improve the stress state of the face, as the value of E has less effect on settlements and shear of the dam than Poisson’s ratio. High rockfill dams with reinforced concrete face may have a favorable stress state only at narrow site when the face horizontal displacements are inconsiderable and due to the settlements of rockfill in the face the forces are compressive but not tensile longitudinal forces.

  1. Studies on Stress-Strain Curves of Aged Composite Solid Rocket Propellants

    Himanshu Shekhar


    Full Text Available Mechanical property evaluation of composite solid rocket propellants is used as a quick quality control tool for propellant development and production. However, stress-strain curves from uni-axial tensile testing can be utilised to assess the shelf-life of propellants also. Composite propellants (CP of two varieties cartridge-loaded (CLCP and case-bonded (CBCP are utilized in rocket and missile applications. Both classes of propellants were evaluated for mechanical properties namely tensile strength, modulus and percentage elongation using specimens conforming to ASTM D638 type IV at different ageing time. Both classes of propellants show almost identical variation in various mechanical properties with time. Tensile strength increases with time for both classes of propellants and percentage elongation reduces. Initial modulus is also found to decrease with time. Tensile strength is taken as degradation criteria and it is observed that CLCP has slower degradation rate than CBCP. This is because of two facts–(i higher initial tensile strength of CLCP (1.39 MPa compared to CBCP (0.665 MPa and (ii lower degradation rate of CLCP (0.0014 MPa/day with respect to CBCP (0.0025 MPa/day. For the studied composite propellants, a degradation criterion in the form of percentage change in tensile strength is evaluated and shelf life for different degradation criteria is tabulated for quick reference.Defence Science Journal, 2012, 62(2, pp.90-94, DOI:


    T. V. Drabysheuskaya


    Full Text Available The paper investigates a stress-strain state in a polycrystalline grain due to presence in its body of a single micro- twin in case of various grain boundary forms. A methodology for calculation of displacement and stress fields for the specified stress-strain state of a polygon-shaped grain has been developed in the paper. Nodal points in a polycrystalline grain that have a maximum stresses contributing to initiation of destruction have been revealed in the paper. The aim of this work has been to study the stress-strain state due to a single micro-twin in the polycrystalline grain and form of grain boundaries. The paper describes polycrystalline grains having a regular polygon shape and containing a single wedge twin in their body. Polycrystalline grain boundaries are presented as walls with complete dislocation. The investigated grains are located far from the surface of twinning material. The developed methodology for calculation of displacement and stresses created by wedge twin is based on the principle of superposition. Calculations on stress tensor components have been carried out for iron (Fe. The presented results of calculations for stress fields have indicated to validity of the used dislocation model. Twin and grain boundaries being stress concentrators are clearly visible on the obtained distributions of stress fields. Maximum normal stresses are observed on the twin boundaries; σxy maximum shear stresses are located at nodal points of the twin; σzy and σxz shear stresses are maximum on the grain boundaries. The conducted investigations have resulted in study of the stress-strain state due to a single wedge-shaped micro-twin in the polycrystalline grain and form of the grain boundaries. Zones of stress concentration in the polycrystalline grain have been identified in the presence of residual mechanical wedge twin. A method for evaluation of the given state has been developed in the paper.

  3. Influence of Loading System Stiffness on Post-peak Stress-Strain Curve of Stable Rock Failures

    Xu, Y. H.; Cai, M.


    It is well known from laboratory testing that the rock failure process becomes unstable in a soft test machine due to excessive energy released from the machine. Great efforts had been devoted to increasing the loading system stiffness (LSS) of laboratory test machines to ensure that the post-peak stress-strain curve of rock can be obtained for underground rock engineering design. A comprehensive literature review on the development of stiff test machines reveals that because of the differences in the manufacturing arrangement of the test machines, LSS values of the test machines used for rock property testing are always finite and vary in a large range, and the influence of LSS on stable rock failure is less understood. A FEM-based numerical experiment is carried out to study the influence of LSS on the stress-strain curves of stable rock failure in uniaxial compression, with a focus on the post-peak deformation stage. Three test machine loadings including idealized rigid loading, platen loading, and frame-platen loading with finite LSS are considered, and the simulation results are analyzed and compared. The modeling results obtained from the simulations indicate that even if the LSS value is large enough to inhibit unstable rock failure, as long as LSS is finite, it has an influence on the post-peak stress-strain curve of rock. It is revealed that because the input energy supplied by the external energy source to drive the stable rock failure process is affected by the finite LSS of a test machine, the post-peak descending slopes of the stress-strain curves are all steeper than the post-peak descending slope obtained under an ideal loading condition of infinite LSS. An insight from this numerical experiment is that it might be more feasible to develop laboratory test machines with variable LSS that can match the local mine stiffness in the field for rock property testing.


    I. S. Kulikov


    Full Text Available The paper considers peculiar features of stress-strain condition of nuclear reactor active zone elements which are under an influence of high temperature and neutron irradiation with due account of thermal and radiation creepage taking jackets of heat releasing elements in the form of hollow thick-walled cylinder as an example. The numerical results of stresses  and deformations which have been obtained with the account of creep strain and without it are presented in the paper.

  5. Frequency-Domain Laser Ultrasound (FDLU) Non-destructive Evaluation of Stress-Strain Behavior in an Aluminum Alloy

    Huan, Huiting; Mandelis, Andreas; Lashkari, Bahman; Liu, Lixian


    The evaluation of the stress-strain state of metallic materials is an important problem in the field of non-destructive testing (NDT). Prolonged cyclic loading or overloading will lead to permanent changes of material strength in an inconspicuous manner that poses threat to the safety of structures, components and products. This research focuses on gauging the mechanical strength of metallic alloys through the application of frequency-domain laser ultrasound (FDLU) based on a continuous-wave diode laser source. The goal is to develop industrial NDT procedures for fatigue monitoring in metallic substrates and coatings so that the technique can be used for mechanical strength assessment. A small-scale, non-commercial rig was fabricated to hold the sample and conduct tensile FDLU testing in parallel with an adhesive strain gauge affixed on the tested sample for independent measurement of the applied stress. Harmonic modulation and lock-in detection were used to investigate the LU signal sensitivity to the stress-strain state of ordinary aluminum alloy samples. A 1 MHz focused piezoelectric transducer was used to detect the LU signal. During the tensile procedure, both amplitude and phase signals exhibited good repeatability and sensitivity to the increasing stress-strain within the elastic regime. Signals beyond the elastic limit also revealed significant change patterns.

  6. Numerical simulation of the stress-strain curve and the stress and strain distributions of the titanium-duplex alloy

    ZHAO Xiqing; ZANG Xinliang; WANG Qingfeng; Park Joongkeun; YANG Qingxiang


    The stress-strain curve of an a-β Ti-8Mn alloy was measured and then it was calculated with finite element method (FEM) based on the stress-strain curves of the single α and β phase alloys.By comparing the calculated stress-strain curve with the measured one,it can be seen that they fit each other very well.Thus,the FE model built in this work is effective.According to the above mentioned model,the distributions of stress and strain in the α and β phases were simulated.The results show that the stress gradients exist in both α and β phases,and the distributions of stress are inhomogeneons.The stress inside the phase is generally higher than that near the interface.Meanwhile,the stress in the α phase is lower than that in the β phase,whereas the strain in the a phase is higher than that in the β phase.

  7. Quantitative ultrasound method for assessing stress-strain properties and the cross-sectional area of Achilles tendon

    Du, Yi-Chun; Chen, Yung-Fu; Li, Chien-Ming; Lin, Chia-Hung; Yang, Chia-En; Wu, Jian-Xing; Chen, Tainsong


    The Achilles tendon is one of the most commonly observed tendons injured with a variety of causes, such as trauma, overuse and degeneration, in the human body. Rupture and tendinosis are relatively common for this strong tendon. Stress-strain properties and shape change are important biomechanical properties of the tendon to assess surgical repair or healing progress. Currently, there are rather limited non-invasive methods available for precisely quantifying the in vivo biomechanical properties of the tendons. The aim of this study was to apply quantitative ultrasound (QUS) methods, including ultrasonic attenuation and speed of sound (SOS), to investigate porcine tendons in different stress-strain conditions. In order to find a reliable method to evaluate the change of tendon shape, ultrasound measurement was also utilized for measuring tendon thickness and compared with the change in tendon cross-sectional area under different stress. A total of 15 porcine tendons of hind trotters were examined. The test results show that the attenuation and broadband ultrasound attenuation decreased and the SOS increased by a smaller magnitude as the uniaxial loading of the stress-strain upon tendons increased. Furthermore, the tendon thickness measured with the ultrasound method was significantly correlated with tendon cross-sectional area (Pearson coefficient = 0.86). These results also indicate that attenuation of QUS and ultrasonic thickness measurement are reliable and potential parameters for assessing biomechanical properties of tendons. Further investigations are needed to warrant the application of the proposed method in a clinical setting.

  8. Characteristics of seismoelectric interface responses at dipping boundaries

    Kröger, B.; Kemna, A.


    When crossing an interface between two layers with different petrophysical properties, a seismic wave generates a time-varying charge separation which acts as a dipole radiating electromagnetic energy independently of the seismic wave. If we consider a monochromatic seismic source located above a horizontal interface between such media, the seismic wave traverses the interface and causes relative displacement of ions at the matrix-fluid interface in the pore space. The resulting electric field is due to the streaming current imbalance at the interface. This is equivalent to the case of an electrical dipole oscillating in phase with the seismic wave along such boundary. As a consequence, electromagnetic disturbances are radiated away from the dipole source and can be recorded at various receiver lines. This seismic-to-electromagnetic field conversion at petrophysical boundaries in the 1st Fresnel zone is the so-called seismoelectric interface response. Conceptual field models and theoretical modelling indicate that the interface response should be a multipole electrical source. Higher-order terms will diminish more rapidly with distance and therefore will leave the dipole term to dominate. Thus, a seismoelectric interface response emanating from a horizontal boundary in a homogeneous half-space is expected to exhibit symmetry and amplitude characteristics similar to those of a vertical electric dipole (VED) centred on the interface directly below the shot point. However, no general theoretical predictions concerning the characteristics, the shape and the morphology of the VED induced by seismic waves at dipping interfaces can be found in the literature. To gain insight into the spatio-temporal occurrence and evolution of the seismoelectric interface response for dipping interfaces we run several numerical simulations using different petrophysical parameter set-ups. For the modelling, we make use of a simplified time-domain formulation of the coupled physical problem

  9. Mathematical Modeling in Systems for Operational Evaluation of the Stress-Strain State of the Arch-Gravity Dam at the Sayano-Shushenskaya Hydroelectric Power Plant

    Bellendir, E. N.; Gordon, L. A., E-mail:; Khrapkov, A. A.; Skvortsova, A. E., E-mail: [B. E. Vedeneev All-Russia Research Institute of Hydraulic Engineering (VNIIG) (Russian Federation)


    Current studies of the stress-strain state of the dam at the Sayano-Shushenskaya Hydroelectric Power Plant at VNIIG based on mathematical modeling including full scale and experimental data are described. Applications and programs intended for automatic operational evaluation of the stress-strain state of the dam for optimizing control of the upper race level in the course of the annual filling-drawdown cycle and during seismic events are examined. Improvements in systems for monitoring the stress-strain state of concrete dams are proposed.

  10. The accuracy and response characteristics of a simplified ear oximeter.

    Chapman, K R; D'Urzo, A; Rebuck, A S


    oximeter (Biox II) were 5.65 seconds and 2.86 seconds in the "normal" and "fast" modes, respectively, by contrast to the 50 percent response time of 2.87 seconds for the other oximeter (H-P 47201A). We conclude that the new oximeter (Biox II) demonstrated accuracy comparable to a more complex and expensive oximeter and had response characteristics that may be useful in clinical and laboratory settings.

  11. Vibration Response Characteristics of the Cross Tunnel Structure

    Jinxing Lai


    Full Text Available It is well known that the tunnel structure will lose its function under the long-term repeated function of the vibration effect. A prime example is the Xi’an cross tunnel structure (CTS of Metro Line 2 and the Yongningmen tunnel, where the vibration response of the tunnel vehicle load and metro train load to the structure of shield tunnel was analyzed by applying the three-dimensional (3D dynamic finite element model. The effect of the train running was simulated by applying the time-history curves of vibration force of the track induced by wheel axles, using the fitted formulas for vehicle and train vibration load. The characteristics and the spreading rules of vibration response of metro tunnel structure were researched from the perspectives of acceleration, velocity, displacement, and stress. It was found that vehicle load only affects the metro tunnel within 14 m from the centre, and the influence decreases gradually from vault to spandrel, haunch, and springing. The high-speed driving effect of the train can be divided into the close period, the rising period, the stable period, the declining period, and the leaving period. The stress at haunch should be carefully considered. The research results presented for this case study provide theoretical support for the safety of vibration response of Metro Line 2 structure.

  12. Analysis of the stress-strain state of New Exchequer combined damat static loads

    Sainov Mikhail Petrovich

    Full Text Available In the article the authors analyze numerical modeling results of the stress-strain state of a combined dam created by construction of a higher rockfill dam with a reinforced concrete face behind the downstream face of the concrete dam. The analysis was conducted on the example of the design of 150 meter high New Exchequer dam (USA. Numerical modeling was conducted with consideration of non-linearity of soils deformation as well as non-linear behavior of the interaction “concrete - soil”, “concrete - concrete”. The analysis showed that though in a combined dam the concrete part gets additional displacements and settlements, its stress state remains favorable without appearance of tensile stresses and opening of the contact “concrete - rock”. This is explained by the fact that on the top the concrete dam is weightened by the reservoir hydrostatic pressure. The role of rockfill lateral pressure on the concrete dam stress state is small. There may be expected sliding of soil in relation to the concrete dam downstream face due to the loss of its shear strength. Besides, decompaction of the contact "soil - concrete" may occur, as earthfill will have considerable displacements in the direction from the concrete dam. Due to this fact the loads from the earthfill weight do not actually transfer to the concrete dam. The most critical zone in the combined dam is the interface of the reinforced concrete face with the concrete dam. Under the action of the hydrostatic pressure the earth-fill under the face will have considerable settlements and displacements, because soil slides in relation to the concrete dam downstream face. This results in considerable openings (10 cm and shear displacements (50 сm in the perimeter joint. The results of the numerical modeling are confirmed by the presence of seepage in New Exchequer dam, which led to the necessity of its repair. Large displacements do not allow using traditional sealing like copper water stops

  13. Numerical Simulation of Similar and Dissimilar Materials Welding Process; Quantifications of Temperature, Stress, Strain and Deformation

    Ranjit Shrestha


    Full Text Available In the present paper, 3 Dimensional welding simulation was carried out in the FE software ANSYS in order to predict temperature, stress, strain and deformation in the joining of similar and dissimilar materials. The numerical simulation shows that temperature exceeds well above the melting temperature of the substrate material in the welding region. It is found that, higher residual stress is distributed in the weld bead area and surrounding heat affected zone. The stress and strain distribution patterns in the specimen showed that both tended to concentrate at or near points of application of thermal load, and were generally not uniform in these areas. It is also found that Stress and strain were concentrated at corners, edges, and other areas of abrupt change in the shape of the specimen and was also not uniform where the cross-section of the structure changed suddenly, and had large gradients at localized points. The deformation was found maximum at the beginning and the end of welding direction (Y-axis and minimum at the ends of X-axis as they are simply supported in both ends. In addition, among the six different cases of similar and dissimilar materials (S40C+S40C, STS304+STS304, STS316L+STS316L, S40C+STS304, S40C+STS316L, STS304+STS316L, the minimum temperature was found in S40C+STS304 whereas the maximum temperature was S40C+STS316L; the minimum stress was found in case of S40C+STS304 and maximum stress was found in 40C+STS316L; the minimum strain was found in case of S40C+STS304 and maximum strain was found in STS304+STS304; the minimum deformation was found in S40C+S40C and maximum in S40C+STS316L.The prediction show qualitative good agreement with the experimental results found in the literature and hence it was confirmed that the method of finite elements has proved to be successful for proper design analysis.

  14. The response characteristics of tetrazolium violet solutions to gamma irradiation

    Emi-Reynolds, G. [Radiation Protection Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Legon-Accra (Ghana)]. E-mail:; Kovacs, Andras [Institute of Isotopes, Hungarian Academy of Sciences, P.O. Box 77, Budapest H-1525 (Hungary); Fletcher, J.J. [Department of Physics, University of Cape Coast, Cape Coast (Ghana)


    The dosimetry characteristics of various solutions of tetrazolium violet, TV, (2,5-diphenyl-3-(1-naphthyl)-2H-tetrazolium chloride) to gamma irradiation are reported. The optical absorption spectra of these solutions show peaks between 400 and 600 nm with a shoulder at around 550 nm. The dose response of the optical absorbance values of aqueous and aqueous-alcoholic solutions containing different concentrations of TV was measured in the 250 Gy up to 75 kGy dose range. The formation of formazan product was observed due to radiolytic reduction in both solutions. Its formation was found more pronounced in N{sub 2}-saturated as well as in alkaline solutions. The results indicate that the 1 mM TV solution can be used for food irradiation and medical sterilization dosimetry at gamma irradiation facilities.

  15. The response characteristics of tetrazolium violet solutions to gamma irradiation

    Emi-Reynolds, G.; Kovács, András; Fletcher, J. J.


    The dosimetry characteristics of various solutions of tetrazolium violet, TV, (2,5-diphenyl-3-(1-naphthyl)-2H-tetrazolium chloride) to gamma irradiation are reported. The optical absorption spectra of these solutions show peaks between 400 and 600 nm with a shoulder at around 550 nm. The dose response of the optical absorbance values of aqueous and aqueous-alcoholic solutions containing different concentrations of TV was measured in the 250 Gy up to 75 kGy dose range. The formation of formazan product was observed due to radiolytic reduction in both solutions. Its formation was found more pronounced in N 2-saturated as well as in alkaline solutions. The results indicate that the 1 mM TV solution can be used for food irradiation and medical sterilization dosimetry at gamma irradiation facilities.

  16. Generation of material stress-strain curves for the parametric study of pipeline buckling[Includes the CSCE forum on professional practice and career development : 1. international engineering mechanics and materials specialty conference : 1. international/3. coastal, estuarine and offshore engineering specialty conference : 2. international/8. construction specialty conference

    Tan, Z.; Khoo, H. [Carleton Univ., Ottawa, ON (Canada). Dept. of Civil and Environmental Engineering


    Failures in steel pipelines are typically preceded by inelastic local buckling which depends on the shape of the material stress-strain curve. Non-dimensional equations can be used to quantify and predict the buckling limits for a range of stress-strain curves found in pipes through parametric finite element analyses. This paper evaluated the feasibility and ease of using an equation to generate the stress-strain curve for a pipe buckling parametric study. A power-law based equation for generating the true stress-true plastic strain curve was adopted. The equation made it possible to quantify the local buckling response to various material stress-strain curves using only a few parameters, such as ultimate to yield strength (proportional limit) ratio, and strain at ultimate stress measured from the end of yield plateau. The same parameters can therefore be used for different material yield strength and length of yield plateau, and enable the development of a more compact material property dependent non-dimensional buckling limit equation. 6 refs., 6 tabs., 3 figs.


    Evgenij Kalentev


    Full Text Available The paper presents the results of a numerical analysis of the stress-strain state of a rope strand with linear contact under tension and torsion loading conditions. Calculations are done using the ANSYS software package. Different approaches to calculation of the stress-strain state of ropes are reviewed, and their advantages and deficiencies are considered. The analysis of the obtained results leads us to the conclusion that the proposed method can be used in engineering calculations.

  18. Effect of Prior Exposure at Elevated Temperatures on Tensile Properties and Stress-Strain Behavior of Four Non-Oxide Ceramic Matrix Composites



  19. Axial and transverse stress-strain characterization of the EU dipole high current density Nb{sub 3}Sn strand

    Nijhuis, A; Ilyin, Y; Abbas, W [Faculty of Science and Technology, Low Temperature Division, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands)], E-mail:


    We have measured the critical current (I{sub c}) of a high current density Nb{sub 3}Sn strand subjected to spatial periodic bending, periodic contact stress and uniaxial strain. The strand is destined for the cable-in-conduit conductors (CICC) of the European dipole (EDIPO) 12.5 T superconducting magnet test facility. The spatial periodic bending was applied on the strand, using the bending wavelengths from 5 to 10 mm with a peak bending strain of 1.5%, a periodic contact stress with a periodicity of 4.7 mm and a stress level exceeding 250 MPa. For the uniaxial strain characterization, the voltage-current characteristics were measured with an applied axial strain from -0.9% to +0.3%, with a magnetic field from 6 to 14 T, temperature from 4.2 to 10 K and currents up to almost 900 A. In addition the axial stiffness was determined by a tensile axial stress-strain test. The characterization of the strand is essential for understanding the behaviour of the strand under mainly axial thermal stress variation during cool down and transverse electromagnetic forces during charging, which is essential for the design of the CICC for the dipole magnet. The strand appears to be fully reversible in the compressive regime during the axial strain testing, while in the tensile regime, the behaviour is already irreversibly degraded when reaching the maximum in the critical current versus strain characteristic. The degradation is accentuated by an immediate decrease of the n value by a factor of 2. The parameters for the improved deviatoric strain description are derived from the I{sub c} data, giving the accuracy of the scaling with a standard deviation of 4 A, which is by far within the expected deviation for the large scale strand production of such a high J{sub c} strand. The I{sub c} versus the applied bending strain follows the low resistivity limit, indicative of full interfilament current transfer, while a strong decrease is observed at a peak bending strain of {approx}0

  20. Responsiveness of muscle tone characteristics to progressive force production.

    Mustalampi, Sirpa; Häkkinen, Arja; Kautiainen, Hannu; Weir, Adam; Ylinen, Jari


    It is possible to measure muscle tone reliably, quickly and objectively using tonometers although they are not yet widely used. In clinical practice, it may be helpful if clinicians could assess the degree of contraction in different parts of a muscle without having to perform time-consuming electromyography measurements. The purpose of this study was to evaluate the responsiveness of different muscle tone characteristics to progressively increased contraction force of quadriceps muscle. Twenty healthy subjects (mean age 39.9 years, 50% women) volunteered. Using 2 different tonometers various muscle viscoelastic properties were measured. The frequency (hertz), logarithmic decrement, and stiffness (newtons per meter) of damped mechanical oscillation of the muscle tissue and tissue compliance (millijoules) were registered from rectus femoris muscle at rest and 20, 40, 60, 80% of maximal voluntary contraction determined using dynamometry. All the values changed linearly with increasing force level. Compliance, oscillation stiffness, and frequency parameters showed large effect sizes (ESs ≥ 0.8). The standardized respoknse mean for compliance was 5.3 (4.8-5.7) mJ, for oscillation stiffness 1.8 (1.3-2.2) N·m(-1), frequency 1.1 (0.6-1.5) Hz, and decrement -0.6 (-1.0 to -0.2). The results indicate that the compliance and oscillation stiffness parameters showed the highest responsiveness and can thus best detect changes in muscle contraction state. The additional value of using tonometers to measure these properties in clinical practice should be investigated further.

  1. A New Method to Evaluate Rock Mass Brittleness Based on Stress-Strain Curves of Class I

    Xia, Y. J.; Li, L. C.; Tang, C. A.; Li, X. Y.; Ma, S.; Li, M.


    Brittleness is a key controlling parameter for rock engineering projects such as hydrocarbon production and other applications. In this paper, commonly used methods based on stress-strain curves of Class I for the calculation of rock brittleness are reviewed. In order to describe the rock brittleness more reasonable, the new index B i was proposed based on the stress drop rate obtained from post-peak stress-strain curve and the ratio of elastic energy released during failure to the total energy stored before the peak strength. Then the validity of B i is verified with experimental tests conducted on rock specimens drilled from the interlayer and oil layer through a well of Shengli Oilfield. Moreover, numerical simulation is performed to analyze the effects of primary mechanical parameters on the brittleness of rock masses. Based on experimental tests and numerical simulation results, the acoustic emission modes influenced by brittleness index B i are summarized. At last, correlation between acoustic emission mechanism and index B i is verified by comparing the acoustic emission modes of limestone under different levels of confining pressure and various types of coal.


    Khodzhiboev Abduaziz Abdusattorovich


    Full Text Available The subject matter of the article represents a solution to the problem of the stress-strain state of a heterogeneous structure resting on the elastic half-plane. The condition of continuity of deformations and stresses alongside the line of contact between the sections of the structure and between the structure and the half-plane is observed; the system of boundary equations is derived on the basis of the above. Coefficients associated with unknown values of the structure are identified with the help of Kelvin's fundamental solutions, while the coefficients associated with the half-plane are identified on the basis of the Mindlin's solutions. The mathematical model and the analytical algorithm developed by the author are implemented within the framework of the examination of the stress-strained state of an earth dam. Analysis of application of the algorithm has proven that concentrated shearing stresses emerge in the area of the upper wall alongside the line of contact between the structure and the half-plane, while mechanical properties of sections of the structure and the half-plane influence the distribution of vertical relocations of the half-plane contour line.

  3. Effects of strain rate, mixing ratio, and stress-strain definition on the mechanical behavior of the polydimethylsiloxane (PDMS) material as related to its biological applications.

    Khanafer, Khalil; Duprey, Ambroise; Schlicht, Marty; Berguer, Ramon


    Tensile tests on Polydimethylsiloxane (PDMS) materials were conducted to illustrate the effects of mixing ratio, definition of the stress-strain curve, and the strain rate on the elastic modulus and stress-strain curve. PDMS specimens were prepared according to the ASTM standards for elastic materials. Our results indicate that the physiological elastic modulus depends strongly on the definition of the stress-strain curve, mixing ratio, and the strain rate. For various mixing ratios and strain rates, true stress-strain definition results in higher stress and elastic modulus compared with engineering stress-strain and true stress-engineering strain definitions. The elastic modulus increases as the mixing ratio increases up-to 9:1 ratio after which the elastic modulus begins to decrease even as the mixing ratio continues to increase. The results presented in this study will be helpful to assist the design of in vitro experiments to mimic blood flow in arteries and to understand the complex interaction between blood flow and the walls of arteries using PDMS elastomer.

  4. Numerical Simulation of Annual Change Patterns of Contemporary Tectonic Stress-Strain Field of the Chinese Mainland

    Chen Lianwang; Yang Shuxin; Xie Furen; Lu Yuanzhong; Guo Ruomei


    Based on the active crustal block structures, the Holocene active faults and the wave velocity structures with a resolution of 1°× 1°, a two-dimensional finite element model for the tectonic stress-strain field of the Chinese mainland is constructed in the paper. Using GPS measurements, the velocity boundary conditions for the model are deduced, then, the annual change patterns of the present-day stress-strain field of the Chinese mainland are simulated.The results show that (1) the general pattern of the recent tectonic deformation in the Chinese mainland is governed by the interactions of its surrounding plates, of which, the Indian Plate plays a major role. There is a NNE-directed velocity distribution in the west of the Chinese mainland. The maximum slip rate appears at the collision boundary. The north-directed components decrease, while the east-directed components increase gradually from south to north and from west to east. In the east part, there is a general east-directed movement, with a certain amount of south-directed components. (2) The present-day tectonic stress field in the Chinese mainland has undergone the process of enhancement in recent years, and this process presents a general pattern of radiating eastwards from the Qinghai-Xizang (Tibet) Plateau as the center. The general pattern is similar to the ambient tectonic stress field, indicating the inheritance of contemporary tectonic deformation on the Chinese mainland. (3) The maximum principal strain presents an obvious pattern of being high in the west and low in the east. The tectonic movement in the west is stronger than that in the east. Large active faults are all located in the high-value zones of maximum principal strain. However, the magnitude of strain is smaller in the interior of the active crustal blocks, which are enclosed by these faults. (4) The stress-strain field of the Sichuan-Yunnan region is unique. It may not be governed by collision of plates alone but a combination of

  5. 应变计组的应力应变转换%Stress-strain conversion of strain gauge set



    为提高应力应变转换最终应力结果的准确度,根据应力应变转换的一般步骤,分析了其中基准时间选取、无应力计可靠性分析、徐变参数公式拟合、应力增量加载方式和应变计组平衡等关键问题,结果表明:基准时间选取缺少一个科学合理的定量原则;无应力计可靠性分析缺少一个可行的分析评判准则;徐变参数公式拟合应该采用全局优化算法;应力增量加载方式应该采用中点瞬时加载终点结束,得到终点时刻应力的方式;对于应变计组平衡问题,基于概率论将平衡问题转化成最优化问题,提出了最优化平衡法,数学实验结果证明该方法是一种科学合理的平衡方法。%In order to improve the accuracy of the final stress result in stress-strain conversion , we analyze some key problems , including the reference time selection , non-stress gauge reliability , formula fitting of creep parameters , stress increment loading mode , and strain gauge set balance , according to general steps of stress-strain conversion .The analysis results show that the reference time selection lacks a scientific and reasonable quantitative principle, the non-stress strain gauge reliability analysis lacks a feasible evaluation criterion , the formula fitting of creep parameters requires a global optimization algorithm , and the stress increment loading mode requires instantaneous loading at the midpoint and ending at the endpoint .Meanwhile , based on the probability theory , the problem of strain gauge set balance is transformed into an optimization problem , and an optimization balance method is put forward , and proven to be scientific and reasonable through a mathematical experiment .

  6. Numerical simulation of gas-dynamic, thermal processes and evaluation of the stress-strain state in the modeling compressor of the gas-distributing unit

    Shmakov, A. F.; Modorskii, V. Ya.


    This paper presents the results of numerical modeling of gas-dynamic processes occurring in the flow path, thermal analysis and evaluation of the stress-strain state of a three-stage design of the compressor gas pumping unit. Physical and mathematical models of the processes developed. Numerical simulation was carried out in the engineering software ANSYS 13. The problem is solved in a coupled statement, in which the results of the gas-dynamic calculation transferred as boundary conditions for the evaluation of the thermal and stress-strain state of a three-stage design of the compressor gas pumping unit. The basic parameters, which affect the stress-strain state of the housing and changing gaps of labyrinth seals in construction. The method of analysis of the pumped gas flow influence on the strain of construction was developed.


    Kh. M. Muselemov


    Full Text Available The work is dedicated to the calculation of the stress-strain state (SSS of the three-layer beam (TLB subject to boundary effects.In this paper, a system of differential equations of equilibrium of the threelayer beam. To solve these equations, it is necessary to know the 12 boundary conditions, co-which depend on support conditions and loading of sandwich beams under study. This system of equations is solved by the application package of mathematical modeling "Maple 5.4." The solution of this system we obtain expressions for determining de-formations and stress all components (bearing layers and filler, a three-layer beam anywhere under specified conditions of fastening the ends of the beam and its loading. 

  8. Mathematical modeling of the stress-strain state of the outlet guide vane made of various materials

    Grinev, M. A.; Anoshkin, A. N.; Pisarev, P. V.; Zuiko, V. Yu.; Shipunov, G. S.


    The present work is devoted to the detailed stress-strain analysis of the composite outlet guide vane (OGV) for aircraft engines with a special focus on areas with twisted layers where the initiation of high interlaminar stresses is most expected. Various polymer composite materials and reinforcing schemes are researched. The technological scheme of laying-out of anisotropic plies and the fastening method are taken into account in the model. The numerical simulation is carried out by the finite element method (FEM) with the ANSYS Workbench software. It is shown that interlaminar shear stresses are most dangerous. It is found that balanced carbon fiber reinforced plastic (CFRP) with the [0°/±45°] reinforcing scheme allows us to provide the double strength margin under working loads for the developed OGV.

  9. Application of a PVDF-based stress gauge in determining dynamic stress-strain curves of concrete under impact testing

    Meng, Yi; Yi, Weijian


    Polyvinylidene fluoride (PVDF) piezoelectric material has been successfully applied in many engineering fields and scientific research. However, it has rarely been used for direct measurement of concrete stresses under impact loading. In this paper, a new PVDF-based stress gauge was developed to measure concrete stresses under impact loading. Calibrated on a split Hopkinson pressure bar (SHPB) with a simple measurement circuit of resistance strain gauges, the PVDF gauge was then used to establish dynamic stress-strain curves of concrete cylinders from a series of axial impact testing on a drop-hammer test facility. Test results show that the stress curves measured by the PVDF-based stress gauges are more stable and cleaner than that of the stress curves calculated with the impact force measured from a load cell.

  10. Stress-strain state in "coating-substrate" system after coating stability loss induced by impact of thermal stresses

    Lyukshin, P. A.; Bochkareva, S. A.; Grishaeva, N. Yu.; Lyukshin, B. A.; Matolygina, N. Yu.; Panin, S. V.


    Thermal barrier coatings (TBC) are aimed at protection of machine parts working under extremely high temperatures. One of the major problems at their exploitation is related to delamination of the coating from the substrate. In this concern, investigation of the patterns and evolution of the stress-strain state (SSS) at their interface is of particular interest. The main reasons of the delamination are associated with the distinction of thermo-physical properties (first of all, thermal expansion coefficient) of the interfaced material, as well as by the difference in heating conditions (heat supply and abstraction). The latter is of particular importance when the transient regimes take place under the heat impact, i.e. the TBC becomes rapidly heated, while the substrate has much lower temperature. In order to analyze and simulate the processes that give rise to the delamination, a number of problems is to be solved. At the first stage, the temperature variation induced by the thermal impact both in the coating and the substrate is to be determined. At the second stage, the distribution of the Stress Strain State (SSS) in the coating and the substrate are to be found. Based on the values of the calculated stresses, the stability loss patterns of the coating might be revealed. In doing so, the latter is regarded as a plate rested on Winkler elastic foundation. By defining the plate deflections in concern of its interaction with the substrate, the distribution of the SSS parameters at the contact surface can be found. Finally, the conditions to determine the TBC delamination from the substrate are estimated.

  11. Transient response characteristics in a biomolecular integral controller.

    Sen, Shaunak


    The cellular behaviour of perfect adaptation is achieved through the use of an integral control element in the underlying biomolecular circuit. It is generally unclear how integral action affects the important aspect of transient response in these biomolecular systems, especially in light of the fact that it typically deteriorates the transient response in engineering contexts. To address this issue, the authors investigated the transient response in a computational model of a simple biomolecular integral control system involved in bacterial signalling. They find that the transient response can actually speed up as the integral gain parameter increases. On further analysis, they find that the underlying dynamics are composed of slow and fast modes and the speed-up of the transient response is because of the speed-up of the slow-mode dynamics. Finally, they note how an increase in the integral gain parameter also leads to a decrease in the amplitude of the transient response, consistent with the overall improvement in the transient response. These results should be useful in understanding the overall effect of integral action on system dynamics, particularly for biomolecular systems.

  12. Characteristics, Responsibilities, and Qualities of Urban School Mentors.

    Guyton, Edith; Hidalgo, Francisco


    Teacher mentors in urban schools need particular characteristics to promote development in beginning teachers because the urban school is a unique environment. Urban mentor teachers need to be able to articulate their beliefs and practices, and they need well-developed coaching skills. (SLD)

  13. Characteristics, Responsibilities, and Qualities of Urban School Mentors.

    Guyton, Edith; Hidalgo, Francisco


    Teacher mentors in urban schools need particular characteristics to promote development in beginning teachers because the urban school is a unique environment. Urban mentor teachers need to be able to articulate their beliefs and practices, and they need well-developed coaching skills. (SLD)

  14. Characteristics of response factors of coaxial gaseous rocket injectors

    Janardan, B. A.; Daniel, B. R.; Zinn, B. T.


    The results of an experimental investigation undertaken to determine the frequency dependence of the response factors of various gaseous propellant rocket injectors subject to axial instabilities are presented. The injector response factors were determined, using the modified impedance-tube technique, under cold-flow conditions simulating those observed in unstable rocket motors. The tested injectors included a gaseous-fuel injector element, a gaseous-oxidizer injector element and a coaxial injector with both fuel and oxidizer elements. Emphasis was given to the determination of the dependence of the injector response factor upon the open-area ratio of the injector, the length of the injector orifice, and the pressure drop across the injector orifices. The measured data are shown to be in reasonable agreement with the corresponding injector response factor data predicted by the Feiler and Heidmann model.

  15. Polymerization Parameters Influencing the QCM Response Characteristics of BSA MIP

    Nam V. H. Phan


    Full Text Available Designing Molecularly Imprinted Polymers for sensing proteins is still a somewhat empirical process due to the inherent complexity of protein imprinting. Based on Bovine Serum Albumin as a model analyte, we explored the influence of a range of experimental parameters on the final sensor responses. The optimized polymer contains 70% cross linker. Lower amounts lead to higher sensitivity, but also sensor response times substantially increase (to up to 10 h at constant imprinting effect (signal ratio MIP/NIP on quartz crystal microbalance—QCM. However, by shifting the polymer properties to more hydrophilic by replacing methacrylic acid by acrylic acid, part of the decreased sensitivity can be recovered leading to appreciable sensor responses. Changing polymer morphology by bulk imprinting and nanoparticle approaches has much lower influence on sensitivity.

  16. Vascularized composite allograft-specific characteristics of immune responses.

    Issa, Fadi


    Vascularized composite allograft (VCA) transplantation, or reconstructive transplantation, has revolutionized the treatment of complex tissue and functional defects. Despite arriving during an age in which the immunology of solid organ transplant rejection has been investigated in much detail, these transplants have offered new perspectives from which to explore the immunobiology of transplantation. VCAs have a number of unique molecular, cellular, and architectural features which alter the character and intensity of the rejection response. While much is yet to be clarified, an understanding of these distinct mechanisms affords new possibilities for the control of immune responses in an effort to improve outcomes after VCA transplantation.

  17. Analysis and Test of Deep Flaws in Thin Sheets of Aluminum and Titanium. Volume 2: Crack Opening Displacement and Stress-Strain Data

    Finger, R. W.


    Static fracture tests were performed on surface flawed specimens of aluminum and titanium alloys. A simulated proof overload cycle was applied prior to all of the cyclic tests. Variables included in each test series were flaw shapes and thickness. Additionally, test temperature was a variable for the aluminum test series. The crack opening displacement and stress-strain data obtained are presented.

  18. Exploring the Ability of a Coarse-grained Potential to Describe the Stress-strain Response of Glassy Polystyrene


    a melt state from reference Isothermal-Isobaric (NPT) Monte Carlo simulations. This CG forcefield was then used to calculate equilibrium properties...DTIC OCA 8725 JOHN J KINGMAN RD STE 0944 FORT BELVOIR VA 22060-6218 1 DIRECTOR US ARMY RESEARCH LAB IMAL HRA 2800 POWDER MILL RD

  19. Stress - Strain Response of the Human Spine Intervertebral Disc As an Anisotropic Body. Mathematical Modeling and Computation

    Minárová Mária


    Full Text Available The paper deals with the biomechanical investigation on the human lumbar intervertebral disc under the static load. The disc is regarded as a two - phased ambient consisting of a fibrous outer part called annulus fibrosis and a liquid inner part nucleus pulposus. Due to the fibrous structure, the annulus fibrosis can be treated by using a special case of anisotropy - transversal isotropy.

  20. Stress-strain response of pre-compacted granular coal samples exposed to CO2, CH4, He and Ar

    Bergen, F. van; Hol, S.; Spiers, C.


    The interaction between supercritical carbon dioxide and coal has been the subject of many studies in recent years. This paper reports two different types of swelling experiments, one on confined and one on unconfined samples of pre-pressed, crushed bituminous coal, performed at gas or fluid

  1. Numerical simulation of the stress-strain state of the dental system

    Lemeshevsky, S. V.; Naumovich, S. A.; Naumovich, S. S.; Vabishchevich, P. N.; Zakharov, P. E.


    We present mathematical models, computational algorithms and software, which can be used for prediction of results of prosthetic treatment. More interest issue is biomechanics of the periodontal complex because any prosthesis is accompanied by a risk of overloading the supporting elements. Such risk can be avoided by the proper load distribution and prediction of stresses that occur during the use of dentures. We developed the mathematical model of the periodontal complex and its software implementation. This model is based on linear elasticity theory and allows to calculate the stress and strain fields in periodontal ligament and jawbone. The input parameters for the developed model can be divided into two groups. The first group of parameters describes the mechanical properties of periodontal ligament, teeth and jawbone (for example, elasticity of periodontal ligament, etc.). The second group characterized the geometric properties of objects: the size of the teeth, their spatial coordinates, the size of periodontal ligament, etc. The mechanical properties are the same for almost all, but the input of geometrical data is complicated because of their individual characteristics. In this connection, we develop algorithms and software for processing of images obtained by computed tomography (CT) scanner and for constructing individual digital model of the tooth-periodontal ligament-jawbone system of the patient. Integration of models and algorithms described allows to carry out biomechanical analysis on three-dimensional digital model and to select prosthesis design.

  2. Stress-strain analysis on AA7075 cylindrical parts during hot granule medium pressure forming

    董国疆; 杨卓云; 赵建培; 赵长财; 曹秒艳


    Hot granule medium pressure forming (HGMF) is a technology in which heat-resistant granules are used to replace liquids or gases in existing flexible-die forming technology as pressure-transfer medium. Considering the characteristic of granule medium that seals and loads easily, the technology provides a new method to realize the hot deep-drawing forming on high strength aluminum alloy sheet. Based on the pressure-transfer performance test of granule medium and the material performance test of AA7075-T6 sheet, plastic mechanics analysis is conducted for the areas, such as the flange area, force-transfer area and free deforming area, of cylindrical parts deep-drawn by HGMF technology, and the function relation of forming pressure is obtained under the condition of nonuniform distribution of internal pressure. The comparison between theoretical result and experimental data shows that larger deviation occurs in the middle and later period of forming process, and the maximum theoretical forming force is less than the experimental value by 24.6%. The variation tendency of the theoretical thickness curve is close to the practical situation, and the theoretical value basically agrees well with experimental value in the flange area and the top area of spherical cap which is in the free deforming area.

  3. Geoacoustic method for continuous monitoring of stressed-strained state of Earth's crust

    Verbitskiy, T. Z.


    Ceramic piezoelectric transducers with characteristic frequencies 10-15 KHz are used as sources and detectors of longitudinal waves in a geoacoustic measuring system. The source is excited by an alternating voltage of 150-300 V with a frequency of 1-10 KHz. The electric signals from the detectors are amplified and filtered for discriminating the frequency harmonics. The phase shift of the received signal of the fundamental frequency and the amplitude of oscillations of the fundamental and multiple frequencies are determined. The measured wave parameters are registered on punched tape, facilitating computer input. Measuring system stability is monitored. The supply voltage, as well as atmospheric pressure, humidity and temperature are continuously monitored. Measurements made in the Carpathian Geodynamic Polygon Carpathian reveal a substantial influence of tidal deformations of the Earth. It can be postulated that short anomalies are caused by the discharge of stresses in the investigated rock complex. More prolonged anomalies are caused by deformations of the crust accompanying preparation for tectonic earthquakes.

  4. Roman Catholic beliefs produce characteristic neural responses to moral dilemmas

    Flexas, Albert; de Miguel, Pedro; Cela-Conde, Camilo J.; Munar, Enric


    This study provides exploratory evidence about how behavioral and neural responses to standard moral dilemmas are influenced by religious belief. Eleven Catholics and 13 Atheists (all female) judged 48 moral dilemmas. Differential neural activity between the two groups was found in precuneus and in prefrontal, frontal and temporal regions. Furthermore, a double dissociation showed that Catholics recruited different areas for deontological (precuneus; temporoparietal junction) and utilitarian moral judgments [dorsolateral prefrontal cortex (DLPFC); temporal poles], whereas Atheists did not (superior parietal gyrus for both types of judgment). Finally, we tested how both groups responded to personal and impersonal moral dilemmas: Catholics showed enhanced activity in DLPFC and posterior cingulate cortex during utilitarian moral judgments to impersonal moral dilemmas and enhanced responses in anterior cingulate cortex and superior temporal sulcus during deontological moral judgments to personal moral dilemmas. Our results indicate that moral judgment can be influenced by an acquired set of norms and conventions transmitted through religious indoctrination and practice. Catholic individuals may hold enhanced awareness of the incommensurability between two unequivocal doctrines of the Catholic belief set, triggered explicitly in a moral dilemma: help and care in all circumstances—but thou shalt not kill. PMID:23160812

  5. Roman Catholic beliefs produce characteristic neural responses to moral dilemmas.

    Christensen, Julia F; Flexas, Albert; de Miguel, Pedro; Cela-Conde, Camilo J; Munar, Enric


    This study provides exploratory evidence about how behavioral and neural responses to standard moral dilemmas are influenced by religious belief. Eleven Catholics and 13 Atheists (all female) judged 48 moral dilemmas. Differential neural activity between the two groups was found in precuneus and in prefrontal, frontal and temporal regions. Furthermore, a double dissociation showed that Catholics recruited different areas for deontological (precuneus; temporoparietal junction) and utilitarian moral judgments [dorsolateral prefrontal cortex (DLPFC); temporal poles], whereas Atheists did not (superior parietal gyrus for both types of judgment). Finally, we tested how both groups responded to personal and impersonal moral dilemmas: Catholics showed enhanced activity in DLPFC and posterior cingulate cortex during utilitarian moral judgments to impersonal moral dilemmas and enhanced responses in anterior cingulate cortex and superior temporal sulcus during deontological moral judgments to personal moral dilemmas. Our results indicate that moral judgment can be influenced by an acquired set of norms and conventions transmitted through religious indoctrination and practice. Catholic individuals may hold enhanced awareness of the incommensurability between two unequivocal doctrines of the Catholic belief set, triggered explicitly in a moral dilemma: help and care in all circumstances-but thou shalt not kill.

  6. Parametric characteristic of the random vibration response of nonlinear systems

    Xing-Jian Dong; Zhi-Ke Peng; Wen-Ming Zhang; Guang Meng; Fu-Lei Chu


    Volterra series is a powerful mathematical tool for nonlinear system analysis,and there is a wide range of non-linear engineering systems and structures that can be represented by a Volterra series model.In the present study,the random vibration of nonlinear systems is investigated using Volterra series.Analytical expressions were derived for the calculation of the output power spectral density (PSD) and input-output cross-PSD for nonlinear systems subjected to Gaussian excitation.Based on these expressions,it was revealed that both the output PSD and the input-output crossPSD can be expressed as polynomial functions of the nonlinear characteristic parameters or the input intensity.Numerical studies were carried out to verify the theoretical analysis result and to demonstrate the effectiveness of the derived relationship.The results reached in this study are of significance to the analysis and design of the nonlinear engineering systems and structures which can be represented by a Volterra series model.

  7. Empirical analysis of the stress-strain relationship between hydraulic head and subsidence in the San Joaquin Valley Aquifer

    Neff, K. L.; Farr, T.


    Aquifer subsidence due to groundwater abstraction poses a significant threat to aquifer sustainability and infrastructure. The need to prevent permanent compaction to preserve aquifer storage capacity and protect infrastructure begs a better understanding of how compaction is related to groundwater abstraction and aquifer hydrogeology. The stress-strain relationship between hydraulic head changes and aquifer compaction has previously been observed to be hysteretic in both empirical and modeling studies. Here, subsidence data for central California's San Joaquin Valley derived from interferometric synthetic aperture radar (InSAR) for the period 2007-2016 is examined relative to hydraulic head levels in monitoring and production wells collected by the California Department of Water Resources. Such a large and long-term data set is available for empirical analysis for the first time thanks to advances in InSAR data collection and geospatial data management. The California Department of Water Resources (DWR) funded this work to provide the background and an update on subsidence in the Central Valley to support future policy. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.

  8. Method of superposition of dislocations for finding stress-strain state around fan-shaped structure in a brittle rock

    Sadovskii, V. M.; Sadovskaya, O. V.


    The Tarasov fan-shaped mechanism, simulating the formation of shear ruptures in a brittle rock at stress conditions corresponding to seismogenic depths, is analyzed. For computation of the stress-strain state of a rock near the equilibrium fan-structure the original method is constructed. The fault is modeled as a narrow elongated layer, filled with the domino-blocks, between two elastic half-spaces. Displacements and stresses around the fan are represented in the integral form as a superposition of edge dislocations with an unknown function of distribution of the Burgers vector. To take into account the stresses of lateral thrust, the solution of plane problem of the elasticity is used for a tensile crack, on the surfaces of which the previously unknown normal stresses are distributed. The exact formulation of the problem leads to a system of two nonlinear singular integral equations, which is solved numerically by the method of successive approximations. The obtained solution is used, when setting the initial data in computations of the dynamics of the Tarasov fan-shaped mechanism. With the help of this solution the discontinuous nature of shear ruptures, observed in natural and laboratory experiments, is explained.

  9. FE Simulation of the Stress-Strain State during Shear-Compression Testing and Asymmetric Three-Roll Rolling Process

    Pesin Alexander


    Full Text Available A three-roll rolling process is a significant technique in the production of wire rod, round bars and hexagonal profiles for structural applications. Better mechanical properties of wire rod, round bars and hexagonal profiles can be achieved due to large plastic deformation by the three-roll rolling process. Asymmetric rolling is a novel technique characterized by a kinematic asymmetry linked to the difference in peripheral speed of the rolls, able to introduce additional shear strains through the bar thickness. Physical simulation of shear strain, which is similar to that occurring in asymmetric three-roll rolling process, is very important for design of technology of producing ultrafine grain materials. Shear testing is complicated by the fact that a state of large shear is not easily achievable in most specimen geometries. Application of the shear-compression testing and specimen geometry to physical simulation of asymmetric three-roll rolling process is discussed in the paper. FEM simulation and comparison of the stress-strain state during shear-compression testing and asymmetric three-roll rolling process is presented. The results of investigation can be used to optimize the physical simulation of asymmetric three-roll rolling processes and for design of technology of producing ultrafine grain materials by severe plastic deformation.

  10. An Experimental Study of Mortars with Recycled Ceramic Aggregates: Deduction and Prediction of the Stress-Strain

    Francisca Guadalupe Cabrera-Covarrubias


    Full Text Available The difficult current environmental situation, caused by construction industry residues containing ceramic materials, could be improved by using these materials as recycled aggregates in mortars, with their processing causing a reduction in their use in landfill, contributing to recycling and also minimizing the consumption of virgin materials. Although some research is currently being carried out into recycled mortars, little is known about their stress-strain (σ-ε; therefore, this work will provide the experimental results obtained from recycled mortars with recycled ceramic aggregates (with contents of 0%, 10%, 20%, 30%, 50% and 100%, such as the density and compression strength, as well as the σ-ε curves representative of their behavior. The values obtained from the analytical process of the results in order to finally obtain, through numerical analysis, the equations to predict their behavior (related to their recycled content are those of: σ (elastic ranges and failure maximum, ε (elastic ranges and failure maximum, and Resilience and Toughness. At the end of the investigation, it is established that mortars with recycled ceramic aggregate contents of up to 20% could be assimilated just like mortars with the usual aggregates, and the obtained prediction equations could be used in cases of similar applications.

  11. Bronchodilator responsiveness as a phenotypic characteristic of established chronic obstructive pulmonary disease

    Albert, Paul; Agusti, Alvar; Edwards, Lisa


    Bronchodilator responsiveness is a potential phenotypic characteristic of chronic obstructive pulmonary disease (COPD). We studied whether change in lung function after a bronchodilator is abnormal in COPD, whether stable responder subgroups can be identified, and whether these subgroups experien...

  12. Facile Fabrication of Composite Membranes with Dual Thermo- and pH-Responsive Characteristics.

    Ma, Bing; Ju, Xiao-Jie; Luo, Feng; Liu, Yu-Qiong; Wang, Yuan; Liu, Zhuang; Wang, Wei; Xie, Rui; Chu, Liang-Yin


    Facile fabrication of novel functional membranes with excellent dual thermo- and pH-responsive characteristics has been achieved by simply designing dual-layer composite membranes. pH-Responsive poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymers and polystyrene blended with thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) nanogels are respectively used to construct the top layer and bottom layer of composite membranes. The stretching/coiling conformation changes of the P4VP chains around the pKa (~3.5-4.5) provide the composite membranes with extraordinary pH-responsive characteristics, and the volume phase transitions of PNIPAM nanogels at the pore/matrix interfaces in the bottom layer around the volume phase transition temperature (VPTT, ~33 oC) provide the composite membranes with great thermo-responsive characteristics. The microstructures, permeability performances and dual stimuli-responsive characteristics can be well tuned by adjusting the content of PNIPAM nanogels and the thickness of the PS-b-P4VP top layer. The water fluxes of the composite membranes can be changed in order of magnitude by changing the environment temperature and pH, and the dual thermo- and pH-responsive permeation performances of the composite membranes are satisfactorily reversible and reproducible. The membrane fabrication strategy in this work provides valuable guidance for further development of dual stimuli-responsive membranes or even multi stimuli-responsive membranes.



    In this paper an item response model (the PARELLA model) designed specifically for the measurement of attitudes and preferences will be introduced. In contrast with the item response models currently used (e.g. the Rasch model and, the two and three parameter logistic model) the item characteristic

  14. Effects of housing and individual coping characteristics in immune responses of pigs

    Bolhuis, J.E.; Parmentier, H.K.; Schouten, W.G.P.; Schrama, J.W.; Wiegant, V.M.


    The impact of environmental factors on immune responses may be influenced by coping characteristics of the individuals under study. The behavioral response of pigs in a so-called Backrest early in life seems indicative of their coping style at a later age. The present study investigated the effects

  15. Response surface methodology for predicting quality characteristics of beef patties added with flaxseed and tomato paste.

    Valenzuela Melendres, M; Camou, J P; Torrentera Olivera, N G; Alvarez Almora, E; González Mendoza, D; Avendaño Reyes, L; González Ríos, H


    Response surface methodology was used to study the effect of flaxseed flour (FS) and tomato paste (TP) addition, from 0 to 10% and 0 to 20% respectively, on beef patty quality characteristics. The assessed quality characteristics were color (L, a, and b), pH and texture profile analysis (TPA). Also, sensory analysis was performed for the assessment of color, juiciness, firmness, and general acceptance. FS addition reduced L and a values and decreased weight loss of cooked products (Psensory characteristics of the cooked product (Psensory characteristics evaluated had an acceptable score (>5.6). Thus FS and TP are ingredients that can be used in beef patty preparation.

  16. Who is responsible for food risks? The influence of risk type and risk characteristics

    Leikas, Sointu; Lindeman, Marjaana; Roininen, Katariina;


    The influence of food risk type and risk characteristics on food risk responsibility judgments was studied. A total of 1270 Finnish consumers judged their personal responsibility and the responsibility of three non-personal targets, industry, retail, and society, in relation to six food......-related risks. They also evaluated the risks on several psychometric dimensions. The ratings were gathered via internet questionnaire. Industry and society were considered to be most responsible for all risks but the risk of cardiovascular disease, for which personal responsibility was considered to be highest....... Judgments of personal controllability predicted personal responsibility judgments, and unnaturalness judgments predicted non-personal targets' judged responsibility. Personal responsibility judgments were related to different risk dimensions than judgments of non-personal targets' responsibility....

  17. Multi-domain simulation of transient junction temperatures and resulting stress-strain behavior of power switches for long-term mission profiles

    Drofenik, U.; Kovacevic, I.; Kolar, J. W. [Swiss Federal Institute of Technology, Power Electronic Systems Laboratory, Zuerich (Switzerland); Schmidt, R. [ABB Switzerland Ltd., Corporate Research, Baden-Daettwil (Switzerland)


    For lifetime estimation of power converters in traction applications, one method is to calculate numerically the stress-strain hysteresis curves of the interfaces silicon-solder-DCB and/or DCB-solder-baseplate inside the power modules. This can only be achieved if the transient junction temperatures in these layers are known for a defined mission profile. Therefore, one has to couple circuit simulation with thermal simulation and stress-strain computation. The second challenge of this problem is to perform this transient simulation taking into account switching losses in the {mu}s-range for mission profiles over a couple of minutes. In this paper we employ a new multi-domain simulation software to achieve results with reasonable computational effort. (author)


    周小平; 张永兴; 哈秋聆; 王建华


    A micromechanics-based model is established. The model takes the interaction among sliding cracks into account, and it is able to quantify the effect of various parameters on the localization condition of damage and deformation for brittle rock subjected to compressive loads. The closed-form explicit expression for the complete stress-strain relation of rock containing microcracks subjected to compressive loads was obtained. It is showed that the complete stress-strain relation includes linear elasticity,nonlinear hardening,rapid stress drop and strain softening.The behavior of rapid stress drop and strain softening is due to localization of deformation and damage. Theoretical predictions have shown to be consistent with the experimental results.

  19. 3D Stress-Strain Analysis of a Failed Limestone Wedge Influenced by an Intact Rock Bridge

    Paronuzzi, Paolo; Bolla, Alberto; Rigo, Elia


    This paper presents a back-analysis of a rock wedge failure (volume = 25-30 m3) that involved a limestone scarp in the Rosandra valley (Trieste karst, NE Italy). Thanks to the mechanical survey of the detachment surface, a single rock bridge having a size of about 15 cm × 30 cm has been ascertained. A 3D stress-strain analysis has been performed to examine the influence of the rock bridge on the block stability (initial unweathered condition: strength reduction factor SRF equal to 1.14). The shear strength provided by the basal and lateral joints represents the main contributing factor for the wedge stability (about 60-75 % of the whole resisting system). However, the equilibrium of the wedge was temporarily attained thanks to the strength contribution provided by the rock bridge (25-40 %) until the acting forces locally exceeded the resisting forces, thus determining the bridge rupture and, as a consequence, the wedge collapse. The mean shear stress acting on the rock bridge at failure ranges from about 3.5 to 5 MPa. Calculated block displacements up to failure vary from 0.6 to 1.5 mm, depending on the different elastic modulus assumed for the wedge ( E = 30, 10, and 4 GPa). Pre-collapse block displacements increase as a result of the shear strength decrease that was initially caused by the weathering of the delimiting rock joints and, further, by the progressive failure of the rock bridge. The cohesion at failure of the rock bridge ranges from 2.1 to 2.6 MPa (friction angle of intact rock φ = 40°).

  20. Stress-strain behavior of block-copolymers and their nanocomposites filled with uniform or Janus nanoparticles under shear: a molecular dynamics simulation.

    Wang, Lu; Liu, Hongji; Li, Fanzhu; Shen, Jianxiang; Zheng, Zijian; Gao, Yangyang; Liu, Jun; Wu, Youping; Zhang, Liqun


    Although numerous research studies have been focused on studying the self-assembled morphologies of block-copolymers (BCPs) and their nanocomposites, little attention has been directed to explore the relation between their ordered structures and the resulting mechanical properties. We adopt coarse-grained molecular dynamics simulation to study the influence of the morphologies on the stress-strain behavior of pure block copolymers and block copolymers filled with uniform or Janus nanoparticles (NPs). At first, we examine the effect of the arrangement (di-block, tri-block, alternating-block) and the components of the pure block copolymers, and by varying the component ratio between A and B blocks, spherical, cylindrical and lamellar phases are all formed, showing that spherical domains bring the largest reinforcing effect. Then by studying BCPs filled with NPs, the Janus NPs induce stronger bond orientation of polymer chains and greater mechanical properties than the uniform NPs, when these two kinds of NPs are both located in the interface region. Meanwhile, some other anisotropic Janus NPs, such as Janus rods and Janus sheets, are incorporated to examine the effect on the morphology and the stress-strain behavior. These findings deepen our understanding of the morphology-mechanics relation of BCPs and their nanocomposites, opening up a vast number of approaches such as designing the arrangement and components of BCPs, positioning uniform or Janus NPs with different shapes and shear flow to tailor their stress-strain performance.

  1. Analysis of stress- strain distribution of dowel and glue line in L-type furniture joint by means of finite element method

    mossayeb dalvand


    Full Text Available In this study 3D stress-strain distribution of dowel and glue line on L-type joints made of plywood doweled was investigated. Members of joints made of 11-ply hardwood plywood (Hornbeam, Beech and Alder that were 19 mm in thickness. In this study effect of beech dowels in three levels diameters (6, 8 and 10 mm and penetration of depth (9, 13 and 17 mm on bending moment capacity of L-type joints under compression loading was investigated as experimental test, then stress-strain distribution of wood dowel and glue line in specimens were simulated by means of ANSYS 15 software with finite element method (FEM.Results have shown that bending moment resistance increased with increasing dowel diameter from 6 to 8 mm, but downward trend was observed with increasing 8 to 10 mm in dowel diameter. Bending moment resistance increased with increasing penetration depth. Also, result obtained of simulation by means of ANSYS software have shown that stress-strain in dowel and glue line increased with increasing diameter of dowel and Increasing stress in joints made of diameter dowel 10 mm due to fracture in joints and decrease in resistance once. According to results obtained of model analysis, the ultimate stress of dowel and glue line occurred in the area that joints were contacted.

  2. A brief history of free-response receiver operating characteristic paradigm data analysis.

    Chakraborty, Dev P


    In the receiver operating characteristic paradigm the observer assigns a single rating to each image and the location of the perceived abnormality, if any, is ignored. In the free-response receiver operating characteristic paradigm the observer is free to mark and rate as many suspicious regions as are considered clinically reportable. Credit for a correct localization is given only if a mark is sufficiently close to an actual lesion; otherwise, the observer's mark is scored as a location-level false positive. Until fairly recently there existed no accepted method for analyzing the resulting relatively unstructured data containing random numbers of mark-rating pairs per image. This report reviews the history of work in this field, which has now spanned more than five decades. It introduces terminology used to describe the paradigm, proposed measures of performance (figures of merit), ways of visualizing the data (operating characteristics), and software for analyzing free-response receiver operating characteristic studies.

  3. Seismic response characteristics of full-size buildings with base isolation system

    Wang, C.Y.; Gvildys, J.


    This paper investigates the response characteristics of full-size reinforced concrete buildings via numerical simulations and actual observations. The test facility consists of two identical three-story buildings constructed side by side at Tohoku University in Sendai, Japan. Since the installation of high-damping isolation bearings in April 1989, data from over twenty earthquakes have been recorded. In this paper, three representative earthquake records, No. 2, No. 6, and No. 17 are used to study the detailed response characteristics. Numerical simulations are carried out with the system response program, SISEC. In general, good agreement has been found between numerical solutions and actual observations. The system is stiff enough to prevent the building displacement under minor earthquakes and wind loads, but is relatively soft for reducing the acceleration response during earthquakes with moderate and strong ground motion. Lessons learned in this effort are applicable to base isolation design of nuclear power plants. 7 refs., 16 figs., 3 tabs.

  4. A Study of the Characteristics of Human-Pilot Control Response to Simulated Aircraft Lateral Motions

    Cheatham, Donald C


    Report presents the results of studies made in an attempt to provide information on the control operations of the human pilot. These studies included an investigation of the ability of pilots to control simulated unstable yawing oscillations, a study of the basic characteristics of human-pilot control response, and a study to determine whether and to what extent pilot control response can be represented in an analytical form.

  5. Neural heterogeneities determine response characteristics to second-, but not first-order stimulus features.

    Metzen, Michael G; Chacron, Maurice J


    Neural heterogeneities are seen ubiquitously, but how they determine neural response properties remains unclear. Here we show that heterogeneities can either strongly, or not at all, influence neural responses to a given stimulus feature. Specifically, we recorded from peripheral electroreceptor neurons, which display strong heterogeneities in their resting discharge activity, in response to naturalistic stimuli consisting of a fast time-varying waveform (i.e., first-order) whose amplitude (i.e., second-order or envelope) varied slowly in the weakly electric fish Apteronotus leptorhynchus. Although electroreceptors displayed relatively homogeneous responses to first-order stimulus features, further analysis revealed two subpopulations with similar sensitivities that were excited or inhibited by increases in the envelope, respectively, for stimuli whose frequency content spanned the natural range. We further found that a linear-nonlinear cascade model incorporating the known linear response characteristics to first-order features and a static nonlinearity accurately reproduced experimentally observed responses to both first- and second-order features for all stimuli tested. Importantly, this model correctly predicted that the response magnitude is independent of either the stimulus waveform's or the envelope's frequency content. Further analysis of our model led to the surprising prediction that the mean discharge activity can be used to determine whether a given neuron is excited or inhibited by increases in the envelope. This prediction was validated by our experimental data. Thus, our results provide key insight as to how neural heterogeneities can determine response characteristics to some, but not other, behaviorally relevant stimulus features.

  6. Step Response Characteristics of Polymer/Ceramic Pressure-Sensitive Paint

    Anshuman Pandey


    Full Text Available Experiments and numerical simulations have been used in this work to understand the step response characteristics of Polymer/Ceramic Pressure-Sensitive Paint (PC-PSP. A recently developed analytical model describing the essential physics in PC-PSP quenching kinetics is used, which includes the effect of both diffusion time scale and luminescent lifetime on the net response of PC-PSP. Step response simulations using this model enables an understanding of the effects of parameters, such as the diffusion coefficient of O2 in the polymer/ceramic coating, attenuation of excitation light, ambient luminescent lifetime, sensitivity, and the magnitude and direction of pressure change on the observed response time scales of PC-PSP. It was found that higher diffusion coefficient and greater light attenuation lead to faster response, whereas longer ambient lifetime and larger sensitivity lead to slower response characteristics. Due to the inherent non-linearity of the Stern-Volmer equation, response functions also change with magnitude and direction of the pressure change. Experimental results from a shock tube are presented where the effects of varying the roughness, pressure jump magnitude and luminophore probe have been studied. Model parameters have been varied to obtain a good fit to experimental results and this optimized model is then used to obtain the response time for a step decrease in pressure, an estimate of which is currently not obtainable from experiments.

  7. The response characteristics of vibration-sensitive saccular fibers in the grassfrog, Rana temporaria

    Christensen-Dalsgaard, J; Jørgensen, M B


    The response characteristics of saccular nerve fibers in European grassfrogs (Rana temporaria) subjected to dorso-ventral, 10-200 Hz sinusoidal vibrations were studied. Only 4 fibers out of a total of 129 did not respond to the vibrations. 70 fibers had an irregular spontaneous activity of 2...

  8. An estimation of load characteristics of an ultrasonic motor by measuring transient responses.

    Nakamura, K; Kurosawa, M; Kurebayashi, H; Ueha, S


    To measure the characteristics of ultrasonic motors, such as the maximum torque, torque-speed relationship and the frictional coefficient at the contact surface, a method in which the torque is calculated from the transient responses is proposed. The rise curve that is the transitional change in the rotor speed soon after turning on the motor gives the load characteristics, while the fall curve that is the decay of the rotor speed after turning off the motor yields the frictional coefficient of the contact surface. This method requires only a short time (the transient time of the motor) to complete the measurement. The relations between the transient responses, the load characteristics and the frictional force are analyzed, and the method is applied to a hybrid transducer type rotary motor and a traveling wave type linear motor.



    The dynamic responses of roller gear indexing cam mechanism are investigated .With applying Lagarange equation and Gear method,motion equations of this mechanism including clearance,motor characteristic,torsion flexibility are developed and solved.The results show that clearance affects primarily the response on turret,and has little effects on the responses on rotary table.At the same time,the velocity fluctuation of motor shaft is not serious for the existence of inertia of reducer,and the high frequency of velocity fluctuation of camshaft is related with the torsion stiffness of shaft and the clearance between pairs.

  10. Field measurement on wind characteristic and buffeting response of the Runyang Suspension Bridge during typhoon Matsa


    Field measurement on wind characteristic and buffeting response of existing bridge is of great value to the development of bridge wind engineering,and the structural health monitoring system(SHMS) em-ployed in many long-span bridges provide a research basis for the field measurement.In order to pro-vide reliable basis for wind resistant evaluation of Runyang Suspension Bridge(RSB),two anemome-ters and 85 accelerometers were installed in the SHMS of RSB.In August 2005,Typhoon Matsa crossed over Jiangsu,the SHMS timely recorded the typhoon and structural vibration responses.In this paper by using the time-frequency technique and statistical theory,the recorded data were analyzed to obtain the strong wind characteristics,the buffeting response characteristics of the cable and deck,and the variation of buffeting response RMS versus wind speed.Results obtained in this study can be em-ployed to validate the credibility of current buffeting response analysis theory techniques,and provide reference values for wind resistant evaluation of other long-span bridges.

  11. Field measurement on wind characteristic and buffeting response of the Runyang Suspension Bridge during typhoon Matsa

    WANG Hao; LI AiQun; GUO Tong; XIE Jing


    Field measurement on wind characteristic and buffeting response of existing bridge is of great value to the development of bridge wind engineering, and the structural health monitoring system (SHMS) em-ployed in many long-span bridges provide a research basis for the field measurement. In order to pro-vide reliable basis for wind resistant evaluation of Runyang Suspension Bridge (RSB), two anemome-ters and 85 accelerometers were installed in the SliMS of RSB. In August 2005, Typhoon Matsa crossed over Jiangsu, the SHMS timely recorded the typhoon and structural vibration responses. In this paper by using the time-frequency technique and statistical theory, the recorded data were analyzed to obtain the strong wind characteristics, the buffeting response characteristics of the cable and deck, and the variation of buffeting response RMS versus wind speed. Results obtained in this study can be em-ployed to validate the credibility of current buffeting response analysis theory techniques, and provide reference values for wind resistant evaluation of other long-span bridges.

  12. Dynamic response characteristics analysis of the doubly-fed wind power system under grid voltage drop

    Chen, Y.; Wang, J.; Wang, H. H.; Yang, L.; Chen, W.; Xu, Y. T.


    Double-fed induction generator (DFIG) is sensitive to the disturbances of grid, so the security and stability of the grid and the DFIG itself are under threat with the rapid increase of DFIG. Therefore, it is important to study dynamic response of the DFIG when voltage drop failure is happened in power system. In this paper, firstly, mathematical models and the control strategy about mechanical and electrical response processes is respectively introduced. Then through the analysis of response process, it is concluded that the dynamic response characteristics are related to voltage drop level, operating status of DFIG and control strategy adapted to rotor side. Last, the correctness of conclusion is validated by the simulation about mechanical and electrical response processes in different voltage levels drop and different DFIG output levels under DIgSILENT/PowerFactory software platform.

  13. Response and Dynamical Stability of Oscillators with Discontinuous or Steep First Derivative of Restoring Characteristic

    Željko Božić


    Full Text Available Response and dynamical stability of oscillators with discontinuous or steep first derivative of restoring characteristic is considered in this paper. For that purpose, a simple single-degree-of-freedom system with piecewise-linear force-displacement relationship subjected to a harmonic force excitation is analysed by the method of piecing the exact solutions (MPES in the time domain and by the incremental harmonic balance method (IHBM in the frequency domain. The stability of the periodic solutions obtained in the frequency domain by IHBM is estimated by the Floquet-Lyapunov theorem. Obtained frequency response characteristic is very complex and includes multi-frequency response for a single frequency excitation, jump phenomenon, multi-valued and non-periodic solutions. Determining of frequency response characteristic in the time domain by MPES is exceptionally time consuming, particularly inside the frequency ranges of co-existence of multiple stable solutions. In the frequency domain, IHBM is very efficient and very well suited for obtaining wide range frequency response characteristics, parametric studies and bifurcation analysis. On the other hand, neglecting of very small harmonic terms (which in-significantly influence the r.m.s. values of the response and are very small in comparison to other terms of the spectrum can cause very large error in evaluation of the eigenvalues of the monodromy matrix, and so they can lead to incorrect prediction of the dynamical stability of the solution. Moreover, frequency ranges are detected inside which the procedure of evaluation of eigenvalues of the monodromy matrix does not converge with increasing the number of harmonics included in the supposed approximate solution.

  14. Quantify patient-specific coronary material property and its impact on stress/strain calculations using in vivo IVUS data and 3D FSI models: a pilot study.

    Guo, Xiaoya; Zhu, Jian; Maehara, Akiko; Monoly, David; Samady, Habib; Wang, Liang; Billiar, Kristen L; Zheng, Jie; Yang, Chun; Mintz, Gary S; Giddens, Don P; Tang, Dalin


    Computational models have been used to calculate plaque stress and strain for plaque progression and rupture investigations. An intravascular ultrasound (IVUS)-based modeling approach is proposed to quantify in vivo vessel material properties for more accurate stress/strain calculations. In vivo Cine IVUS and VH-IVUS coronary plaque data were acquired from one patient with informed consent obtained. Cine IVUS data and 3D thin-slice models with axial stretch were used to determine patient-specific vessel material properties. Twenty full 3D fluid-structure interaction models with ex vivo and in vivo material properties and various axial and circumferential shrink combinations were constructed to investigate the material stiffness impact on stress/strain calculations. The approximate circumferential Young's modulus over stretch ratio interval [1.0, 1.1] for an ex vivo human plaque sample and two slices (S6 and S18) from our IVUS data were 1631, 641, and 346 kPa, respectively. Average lumen stress/strain values from models using ex vivo, S6 and S18 materials with 5 % axial shrink and proper circumferential shrink were 72.76, 81.37, 101.84 kPa and 0.0668, 0.1046, and 0.1489, respectively. The average cap strain values from S18 material models were 150-180 % higher than those from the ex vivo material models. The corresponding percentages for the average cap stress values were 50-75 %. Dropping axial and circumferential shrink consideration led to stress and strain over-estimations. In vivo vessel material properties may be considerably softer than those from ex vivo data. Material stiffness variations may cause 50-75 % stress and 150-180 % strain variations.

  15. Study of the stress-strain behavior of floodable rockfills by means of finite difference formulated numerical simulations and instrumentation records

    Escuder Bueno, Ignacio

    This Thesis studies the stress-strain behavior of floodable rockfills, using data obtained from quality control of materials, control of construction and instrumentation records. As a case of study, a rockfill part of the final works for a new Madrid-Valencia motorway, located at Contreras Reservoir is used. Data were collected during construction (December 1997--August 1998) and are extended to July of 2000. After reviewing the state of art on properties of usual materials, models of behaviour, numerical tools and experiences dealing with studies based in combined analysis and field measurements, several works have been developed. Namely the synthesis of all available data, study of construction procedures, implementation of an analysis methodology and its application to the study of the stress-strain behavior during and after construction. FLAC 2D (Itasca, 1994), an explicit finite difference code, has been selected as numerical tool to perform the analysis, and results have been compared with measurements registered by total pressure and settlement cells. In order to improve the quality of analysis and to make use of all collected records to calibrate the models (taken on a weekly basis), the real constructive sequency has been simulated. Numerical calculation based in linear elastic, non linear elastic, elastoplastic and viscoelastic models have been performed. Newly developed routines have permitted to accomplish the upgrading of tangent parameters involved in non-linear hyperbolic formulation, calculation of creep deformation and settlements due to reservoir filling. As a result of the works, the stress-strain behavior of the structure has been characterized, the importance of creep deformation from first stages of construction has been identified, and capability of usually assumed models in reproducing observed behavior has been evaluated.

  16. Health Systems' Responsiveness and Its Characteristics: A Cross-Country Comparative Analysis

    Robone, Silvana; Rice, Nigel; Smith, Peter C


    Objectives Responsiveness has been identified as one of the intrinsic goals of health care systems. Little is known, however, about its determinants. Our objective is to investigate the potential country-level drivers of health system responsiveness. Data Source Data on responsiveness are taken from the World Health Survey. Information on country-level characteristics is obtained from a variety of sources including the United Nations Development Program (UNDP). Study Design A two-step procedure. First, using survey data we derive a country-level measure of system responsiveness purged of differences in individual reporting behavior. Secondly, we run cross-sectional country-level regressions of responsiveness on potential drivers. Principal Findings Health care expenditures per capita are positively associated with responsiveness, after controlling for the influence of potential confounding factors. Aspects of responsiveness are also associated with public sector spending (negatively) and educational development (positively). Conclusions From a policy perspective, improvements in responsiveness may require higher spending levels. The expansion of nonpublic sector provision, perhaps in the form of increased patient choice, may also serve to improve responsiveness. However, these inferences are tentative and require further study. PMID:21762144

  17. Flow-rate Characteristics Measurement of Regulators Based on the Pressure Response in an Isothermal Tank

    FAN Wei; ZHANG Hongli; WANG Tao; PENG Guangzheng; ONEYAMA Naotake


    Regulators are important components in pneumatic system, and their flow-rate characteristics are the key parameters for designers. According to the correlatively international standard and national standard of China, which describe the flow-rate characteristics measurement method of pneumatic regulators, the pressure and the flow are measured point by point, and then the flow-rate characteristics curve is plotted point to point. This method has some disadvantages, such as equipment complexity, much air consumption, and low efficiency. To settle the problems presented above, this paper puts forward a new high efficient and energy saving flow-rate characteristics measurement method of regulators, which is based on the pressure response when charging and discharging to an isothermal tank without any flow meters. The measurement principle, the system and the steps are introduced. And the tracking differentiator is used for the data processing of the pressure difference. Two typical kinds of regulators were experimentally investigated, and their flow-rate characteristics curves were obtained with the new and the conventional method, respectively. Comparatively, it's proved that this new method is feasible because it is not only able to meet the demand of the measurement precision, but also to save energy and improve efficiency. Compared to the conventional method, the new method takes only about 1/10 amount of time and consumes about only 1/30 amount of air. Hopefully it will be able to serve as an international standard of flow-rate characteristics measurement method of regulators.

  18. Response Characteristics of Bisphenols on a Metal-Organic Framework-Based Tyrosinase Nanosensor.

    Lu, Xianbo; Wang, Xue; Wu, Lidong; Wu, Lingxia; Dhanjai; Fu, Lei; Gao, Yuan; Chen, Jiping


    Bisphenols (BPs), which have more than ten kinds of structural analogues, are emerging as the most important endocrine disrupting chemicals that adversely affect human health and aquatic life. A tyrosinase nanosensor based on metal-organic frameworks (MOFs) and chitosan was developed to investigate the electrochemical response characteristics and mechanisms of nine kinds of BPs for the first time. The developed tyrosinase nanosensor showed a sensitive response to bisphenol A, bisphenol F, bisphenol E, bisphenol B, and bisphenol Z, and the responsive sensitivities were highly dependent on their respective log Kow values. However, the nanosensor showed no response to bisphenol S (BPS), bisphenol AP (BPAP), bisphenol AF (BPAF), or tetrabromobisphenol A, although BPS, BPAP, and BPAF have structures similar to those of the responsive BPs. The obtained results reveal that the electrochemical response of different BPs is affected not only by the molecular structure, especially the available ortho positions of phenolic hydroxyl groups, but also by the substituent group properties (electron acceptor or electron donor) on the bisphenol framework. The electronic cloud distribution of the phenolic hydroxyl groups, which is affected by the substituent group, determines whether the available ortho positions of phenolic hydroxyl groups can be oxidized by the tyrosinase biosensor. These response mechanisms are very significant as they can be used for predicting the response characteristics of many BPs and their various derivatives and metabolites on biosensors. The unexpected anti-interference ability of the biosensor to nine heavy metal ions was also discovered and discussed. The MOF-chitosan nanocomposite proves to be a promising sensing platform for the construction of diverse biosensors for selective detection of targets even in the presence of a high concentration of heavy metal ions.

  19. Hydrothermal Synthesis and Responsive Characteristics of Hierarchical Zinc Oxide Nanoflowers to Sulfur Dioxide

    Qu Zhou


    Full Text Available Sulfur dioxide, SO2, is one of the most important decomposition byproducts of sulfur hexafluoride, SF6, under partial discharge in GIS apparatus. The sensing performances of semiconductor gas sensors can be improved by morphology tailoring. This paper reported the synthesis method, structural characterization, and SO2 responsive characteristics of hierarchical flower-shaped ZnO nanostructures. Hierarchical ZnO nanoflowers were successfully prepared via a facile and simple hydrothermal method and characterized by X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, respectively. Planar chemical gas sensor was fabricated and its responsive characteristics towards SO2 were systematically performed. The optimum operating temperature of the fabricated sensor was measured to be about 260°C, and the corresponding maximum responses were 16.72 and 26.14 to 30 and 60 ppm of SO2. Its saturated gas concentration was 2000 ppm with a response value of 67.41. Moreover, a quick response and recovery feature (7 s and 8 s versus 80 ppm of SO2 and good stability were also observed. All results indicate that the proposed sensor is a promising candidate for detecting SF6 decomposition byproduct SO2.

  20. Application backwards characteristics analysis method to dynamic response of metals under high pressure

    Pan Hao


    Full Text Available Dynamic yield strength of metals/alloys depends on loading pressure and rates sensitively. With the development of laser interferometer measurement system, extracting strength information from window/free surface velocity profiles in shock and ramp loading experiments is becoming an important method to investigate materials’ dynamic response under high pressure and high strain rates. Backwards characteristics analysis method (BCAM can analyze the velocity profiles more reasonable because it accounts for bending of the incoming characteristics due to impedance mismatch between the sample and window. Synthetic analyses of reverse impact experiment and graded-density impactor loading-releasing experiment suggest that BCAM can give more accurate results including sound speed-particle velocity and yield strength at high pressure than incremental impedance matching method. We use BCAM to analyze velocity profiles of Sn in shock-release experiments and obtain its shear modulus and yield strength at different shock pressure and investigate its phase transition and dynamic unloading response.

  1. Back-propagation neural network-based approximate analysis of true stress-strain behaviors of high-strength metallic material

    Doh, Jaeh Yeok; Lee, Jong Soo [Yonsei University, Seoul (Korea, Republic of); Lee, Seung Uk [Gyeongbuk Hybrid Technology Institute, Yeongcheon (Korea, Republic of)


    In this study, a Back-propagation neural network (BPN) is employed to conduct an approximation of a true stress-strain curve using the load-displacement experimental data of DP590, a high-strength material used in automobile bodies and chassis. The optimized interconnection weights are obtained with hidden layers and output layers of the BPN through intelligent learning and training of the experimental data; by using these weights, a mathematical model of the material's behavior is suggested through this feed-forward neural network. Generally, the material properties from the tensile test cannot be acquired until the fracture regions, since it is difficult to measure the cross-section area of a specimen after diffusion necking. For this reason, the plastic properties of the true stress-strain are extrapolated using the weighted-average method after diffusion necking. The accuracies of BPN-based meta-models for predicting material properties are validated in terms of the Root mean square error (RMSE). By applying the approximate material properties, the reliable finite element solution can be obtained to realize the different shapes of the finite element models. Furthermore, the sensitivity analysis of the approximate meta-model is performed using the first-order approximate derivatives of the BPN and is compared with the results of the finite difference method. In addition, we predict the tension velocity's effect on the material property through a first-order sensitivity analysis.

  2. Measurement of large deformation of nylon cord-rubber composite and effects of perpendicular loads on its stress-strain behaviors

    张丰发; 杜星文; 于增信


    Effects of transverse loads on longitudinal stress-strain behaviors and longitudinal constant tensile loads on transverse stress-strain behaviors of single ply of nylon cord-rubber composite are studied respectively under biaxial tensile condition with cruciform specimen. Effects of transverse constant tensile load on longitudinal tensile mechanical properties are indistinctive compared with corresponding uniaxial longitudinal tensile mechanical properties. It can be relative to larger difference between longitudinal and transverse mechanical properties. Its dominating failure mode is typical fiber-dominated mode; However, Experiment results indicate that transverse mechanical properties of nylon cord-rubber composite with longitudinal constant tensile loads are distinct from its uniaxial transverse tensile mechanical properties. It can be attribute to action of longitudinal tension that makes material rigidify in the direction perpendicular to fiber, Mode of failure is representative of matrix-dominated failure. For the measurement of large deformation up to 50 percent, a special CCD imaging method is employed in the experimental investigation that makes measurement of large deformations more precise.

  3. Recent structures and tectonic regimes of the stress-strain state of the Earth's crust in the northeastern sector of the Russian Arctic region

    Imaeva, L. P.; Imaev, V. S.; Mel'nikova, V. I.; Koz'min, B. M.


    A comprehensive investigation aimed at determining seismotectonic types of destruction and the stress-strain state of the Earth's crust in the main seismogenerating structures of the Arctic-Asian seismic belt is conducted for the territory of the northeastern sector of the Russian Arctic region. Based on the degree of activity of geodynamical processes, the regional principles for ranking neotectonic structures are elaborated, and neotectonic zoning is carried out based on the substantiated differentiation of the corresponding classes. Within the limits of the Laptev Sea, Kharaulakh, and Lena-Anabar segments, we analyzed I the structural-tectonic position of the most recent structures, II the deep structure parameters, III the parameters of the active fault system, and IV the parameters of the tectonic stress field, as revealed from tectonophysical analysis of Late Cenozoic fault and fold deformations. Based on the seismological data, the mean seismotectonic deformation tensors are calculated to determine, in combination with geological and geophysical data, the orientations of the principal stress axes and to reveal the structural-tectonic regularity for tectonic regimes of the stress-strain state of the Earth's crust in the Arctic sector of the boundary between the Eurasian and North American lithospheric plates.

  4. How soft is a single protein? The stress-strain curve of antibody pentamers with 5 pN and 50 pm resolutions.

    Perrino, Alma P; Garcia, Ricardo


    Understanding the mechanical functionalities of complex biological systems requires the measurement of the mechanical compliance of their smallest components. Here, we develop a force microscopy method to quantify the softness of a single antibody pentamer by measuring the stress-strain curve with force and deformation resolutions, respectively, of 5 pN and 50 pm. The curve shows three distinctive regions. For ultrasmall compressive forces (5-75 pN), the protein's central region shows that the strain and stress are proportional (elastic regime). This region has an average Young's modulus of 2.5 MPa. For forces between 80 and 220 pN, the stress is roughly proportional to the strain with a Young's modulus of 9 MPa. Higher forces lead to irreversible deformations (plastic regime). Full elastic recovery could reach deformations amounting to 40% of the protein height. The existence of two different elastic regions is explained in terms of the structure of the antibody central region. The stress-strain curve explains the capability of the antibody to sustain multiple collisions without any loss of biological functionality.

  5. Characteristics of identifying linear dynamic models from impulse response data using Prony analysis

    Trudnowski, D.J.


    The purpose of the study was to investigate the characteristics of fitting linear dynamic models to the impulse response of oscillatory dynamic systems using Prony analysis. Many dynamic systems exhibit oscillatory responses with multiple modes of oscillations. Although the underlying dynamics of such systems are often nonlinear, it is frequently possible and very useful to represent the system operating about some set point with a linear model. Derivation of such linear models can be done using two basic approaches: model the system using theoretical derivations and some linearization method such as a Taylor series expansion; or use a curve-fitting technique to optimally fit a linear model to specified system response data. Prony analysis belongs to the second class of system modeling because it is a method of fitting a linear model to the impulse response of a dynamic system. Its parallel formulation inherently makes it well suited for fitting models to oscillatory system data. Such oscillatory dynamic effects occur in large synchronous-generator-based power systems in the form of electromechanical oscillations. To study and characterize these oscillatory dynamics, BPA has developed computer codes to analyze system data using Prony analysis. The objective of this study was to develop a highly detailed understanding of the properties of using Prony analysis to fit models to systems with characteristics often encountered in power systems. This understanding was then extended to develop general ``rules-of-thumb`` for using Prony analysis. The general characteristics were investigated by performing fits to data from known linear models under controlled conditions. The conditions studied include various mathematical solution techniques; different parent system configurations; and a large variety of underlying noise characteristics.

  6. Characteristics of identifying linear dynamic models from impulse response data using Prony analysis

    Trudnowski, D.J.


    The purpose of the study was to investigate the characteristics of fitting linear dynamic models to the impulse response of oscillatory dynamic systems using Prony analysis. Many dynamic systems exhibit oscillatory responses with multiple modes of oscillations. Although the underlying dynamics of such systems are often nonlinear, it is frequently possible and very useful to represent the system operating about some set point with a linear model. Derivation of such linear models can be done using two basic approaches: model the system using theoretical derivations and some linearization method such as a Taylor series expansion; or use a curve-fitting technique to optimally fit a linear model to specified system response data. Prony analysis belongs to the second class of system modeling because it is a method of fitting a linear model to the impulse response of a dynamic system. Its parallel formulation inherently makes it well suited for fitting models to oscillatory system data. Such oscillatory dynamic effects occur in large synchronous-generator-based power systems in the form of electromechanical oscillations. To study and characterize these oscillatory dynamics, BPA has developed computer codes to analyze system data using Prony analysis. The objective of this study was to develop a highly detailed understanding of the properties of using Prony analysis to fit models to systems with characteristics often encountered in power systems. This understanding was then extended to develop general rules-of-thumb'' for using Prony analysis. The general characteristics were investigated by performing fits to data from known linear models under controlled conditions. The conditions studied include various mathematical solution techniques; different parent system configurations; and a large variety of underlying noise characteristics.

  7. Stability of response characteristics of a Delphi panel: application of bootstrap data expansion

    Cole Bryan R


    Full Text Available Abstract Background Delphi surveys with panels of experts in a particular area of interest have been widely utilized in the fields of clinical medicine, nursing practice, medical education and healthcare services. Despite this wide applicability of the Delphi methodology, there is no clear identification of what constitutes a sufficient number of Delphi survey participants to ensure stability of results. Methods The study analyzed the response characteristics from the first round of a Delphi survey conducted with 23 experts in healthcare quality and patient safety. The panel members had similar training and subject matter understanding of the Malcolm Baldrige Criteria for Performance Excellence in Healthcare. The raw data from the first round sampling, which usually contains the largest diversity of responses, were augmented via bootstrap sampling to obtain computer-generated results for two larger samples obtained by sampling with replacement. Response characteristics (mean, trimmed mean, standard deviation and 95% confidence intervals for 54 survey items were compared for the responses of the 23 actual study participants and two computer-generated samples of 1000 and 2000 resampling iterations. Results The results from this study indicate that the response characteristics of a small expert panel in a well-defined knowledge area are stable in light of augmented sampling. Conclusion Panels of similarly trained experts (who possess a general understanding in the field of interest provide effective and reliable utilization of a small sample from a limited number of experts in a field of study to develop reliable criteria that inform judgment and support effective decision-making.

  8. Experimental Study on Excavation Characteristics of Rockmass by Triaxial Test

    谢红强; 姚勇; 何川; 杨庆


    Applying MTS rock stiffness test machine, tests under triaxial condition were carried out for rockmass under loading and unloading. By measuring and analyzing such mechanical properties as stress, strain, elastic modulus, Poisson ratio and elastic wave velocity during the whole test process, the differences of mechanical characteristics under loading and unloading conditions were revealed, to provide some useful references for excavation.

  9. The strange case of online surveys: response issues and respondent characteristics

    Adamsen, Jannie Mia; Rundle-Thiele, Sharyn; Mehnert, Christina


    This research contributes to existing knowledge about collecting data online by analysing multiple data sets on key criteria including overall representativeness of the samples, response and break-off rates, timeliness of response and reminder effects. Across eight online surveys that initially...... in responses on the preference measures for Leaders, Early or Late Majority or Laggards and secondly, we have only considered the demographic characteristics of responders. The information can be utilised by researchers in the planning and management process of online surveys, especially since the results...... a reminder 48-72 hours after the initial invitation and closing the survey one to two days later; based on our results this time-wise approach still captures 90% of respondents. This study must be viewed in light of some key limitations. Firstly, we have not considered whether there are differences...

  10. Review of Articles Related to Responsiveness as a Characteristic of Quality of Life Instruments

    Rostam Jalali


    Full Text Available Introduction: Responsiveness is a concept introduced in the mid-eighties by bio-medical researchers. It is considered as a fundamental feature of health-related quality of life questionnaires, which was different from reliability and validity. Responsiveness is defined as the ability of an instrument to detect the minimal clinically important differences. Most authors agree that responsiveness focuses on the ability of a criterion in measuring changes, but there is a wide variety of opinions about the nature of quantified change. This review study was performed to determine the responsiveness by using the valid and available articles. Methods: Keywords of "responsiveness" and "quality of life" were searched in Cumulative Index to Nursing and Allied Health Literature (CINAHL, ProQuest, PsycINFO, Science Direct, Scopus, and Medline databases. Results: Multiple definitions for responsiveness and different procedures for calculating it were investigated in various studies. A total of 30 articles were used as references. Responsiveness has been divided into two groups: External and internal. “Internal responsiveness” is defined as the ability of a measure to change over a specified time frame. “External responsiveness” reflects the extent to which changes in a measure over a specified time frame relate to corresponding changes in a reference measure of health status. Conclusion: Despite the fact that some authors consider the responsiveness as the most basic characteristics for assessment of a tool, its measurement methodology is different. Meanwhile, there are different methods to assess responsiveness, but the researchers used one of them, and in development and validation of quality of life questionnaires must be regarded.

  11. Multi-Objective Demand Response Model Considering the Probabilistic Characteristic of Price Elastic Load

    Shengchun Yang


    Full Text Available Demand response (DR programs provide an effective approach for dealing with the challenge of wind power output fluctuations. Given that uncertain DR, such as price elastic load (PEL, plays an important role, the uncertainty of demand response behavior must be studied. In this paper, a multi-objective stochastic optimization problem of PEL is proposed on the basis of the analysis of the relationship between price elasticity and probabilistic characteristic, which is about stochastic demand models for consumer loads. The analysis aims to improve the capability of accommodating wind output uncertainty. In our approach, the relationship between the amount of demand response and interaction efficiency is developed by actively participating in power grid interaction. The probabilistic representation and uncertainty range of the PEL demand response amount are formulated differently compared with those of previous research. Based on the aforementioned findings, a stochastic optimization model with the combined uncertainties from the wind power output and the demand response scenario is proposed. The proposed model analyzes the demand response behavior of PEL by maximizing the electricity consumption satisfaction and interaction benefit satisfaction of PEL. Finally, a case simulation on the provincial power grid with a 151-bus system verifies the effectiveness and feasibility of the proposed mechanism and models.

  12. A study on operators' cognitive response characteristics to the computerized working environment

    Lee, Yong Hee; Lee, Jang Soo; Suh, Sang Moon; Lee, Hyun Cheol; Jung, Kwang Tae; Lee, Dhong Ha


    Although the introduction of computerized working environment to the nuclear facilities, the study on the human factors impacts of computers and automation has not been enough like the other industries. It is necessary to prepare the way to cope with the negative aspects in spite of many positive aspects of computerization in nuclear. This study is an empirical study including the survey of the human factor concerning, especially to the cognitive response of operators' and the experiments on the error proneness. At first, we survey the design and its changes of operator interface and interaction in nuclear power plants, and conclude five human factor issues. We discuss situation awareness issues as one of the major human factor concerning, and the assessment method. Secondly, a questionnaire and interviews survey to the operator's response characteristics are performed for possible criterion measures to the in-depth study on the cognitive characteristics. Finally, several experiments are conducted to test the error proneness. The issues and findings of this study could be utilized to any further study on the cognitive characteristic of operators to the computerized work environment.

  13. Differential Responses to Food Price Changes by Personal Characteristic: A Systematic Review of Experimental Studies.

    Anja Mizdrak

    Full Text Available Fiscal interventions to improve population diet have been recommended for consideration by many organisations including the World Health Organisation and the United Nations and policies such as sugar-sweetened beverage taxes have been implemented at national and sub-national levels. However, concerns have been raised with respect to the differential impact of fiscal interventions on population sub-groups and this remains a barrier to implementation.To examine how personal characteristics (such as socioeconomic status, sex, impulsivity, and income moderate changes in purchases of targeted foods in response to food and beverage price changes in experimental settings.Systematic review.Online databases (PubMed, EMBASE, Web of Science, EconLit and PsycInfo, reference lists of previous reviews, and additional data from study authors.We included randomised controlled trials where food and beverage prices were manipulated and reported differential effects of the intervention on participant sub-groups defined according to personal characteristics.Where possible, we extracted data to enable the calculation of price elasticities for the target foods by personal characteristic.8 studies were included in the review. Across studies, the difference in price elasticity varied from 0.02 to 2.43 between groups within the same study. 11 out of the total of 18 comparisons of own-price elasticity estimates by personal characteristic differed by more than 0.2 between groups. Income related factors were the most commonly considered and there was an indication that own-price elasticity estimates do vary by income but the direction of this effect was not clear.Experimental studies provide an opportunity to examine the differential effects of fiscal measures to improve population diets. Patterns in price sensitivity by personal characteristics are complex. General conclusions pertaining to the effects of personal characteristics on price sensitivity are not supported by

  14. Mathematical modeling of stress-strain state of the system HPP building - soil base with account for the phased construction of the building

    Orekhov Vyacheslav Valentinovich

    Full Text Available The interaction process of a power plant building with the soil base is studied basing on mathematical modeling of the construction process of Kambarata-2 HPP, taking into account the excavation of foundation pit, the concreting schedule of the building construction, the HPP units putting into operation and territory planning. Mathematical modeling of stress-strain state of the system “power plant - soil base” in the process of construction was performed by using the computer program “Zemlya” (the Earth, which implements the method of finite elements. Such a behavior of soil was described using elastoplastic soil model, the parameters of which were determined from the results of the triaxial tests. As shown by the results of the research, the continuous change of settlement, slope, deflection and torsion of the bottom plate and accordingly change of stressed-strained state of power plant are noted during the construction process. The installed HPP construction schedule, starting from the construction of the first block and the adjacent mounting platform, is leading to the formation of initial roll of bottom plate to the path of the mounting pad. In the process of further construction of powerhouse, up to the 29th phase of construction (out of 40, a steady increase in its subsidence (maximum values of about 4.5 cm is noted. Filling of foundation pit hollows and territorial planning of the construction area lead to drastic situation. In this case, as a territory planning points exceeded the relief, the plastic deformation in the soil evolves, resulting in significant subsidence of the bottom plate under the first block (up to 7.4 cm. As a result, the additional subsidence of the soil of bottom plate edges lead to the large vertical movement in relation to its central part and it is bent around the X axis, resulting in a large horizontal tensile stress values of Sz (up to 2.17 MPa in the constructive elements of the upper part of the



    The investigation of complete stress-strain behavior andcompressive failure behavior of some Hong Kong rocks are carried out. A large number of tests have been conducted to study the deformation and failure features of rocks. Some interesting test results have been obtained. These results show that localized deformation and failure strongly affect the deformation and failure process of the specimens just prior to the peak stress and in the post-peak stage. The two types of failure modes, namely exfoliation and shear failure have been investigated in detail. For the exfoliation failure mode, an experiment method has been proposed to observe the exfoliating process. A proposed model has been used to explain the influence of exfoliation on the gross stress-strain curve. It is found that the exfoliation during loading may be one of the reasons that a granite specimen exhibits Class Ⅱ behavior. The influences of machine stiffness control modes, end constraints, loading rate and confining pressure on the test results have been discussed and investigated. A new classification method of rock failure has been proposed. Special attention has been devoted to the investigation of the localized deformation and failure process of intact rock in the shear failure mode. A test method is proposed to detect the process. It is found that the deformation of rock material may be divided into three stages: namely uniform stage, pre-peak bifurcation stage and post-peak bifurcation stage. This phenomenon has been explained by a proposed qualitative analysis. It is further found that this localized process will significantly influence the shape of stress-strain curves, that is, the localized deformation is one of reasons that rock displays the effect of length to diameter ratio. A constitutive model is proposed to simulate the localized deformation and failure process. It can simulate the strain softening, strain localization, effect of length to diameter(L/D) ratio, unloading

  16. Vibration Response and Power Flow Characteristics of a Flexible Manipulator with a Moving Base

    Yufei Liu


    Full Text Available Flexible manipulator generally can be modeled as a coupling system with a flexible beam and a rigid moving base. This paper investigates the vibration responses and power flow of a flexible manipulator with a moving base (FMMB. Considering the motion characteristics of the rigid base, the moving base is modeled to have a motion with disturbances, and the dynamic model of the FMMB is established. With the dynamic model, vibration responses of the FMMB for the rigid base having disturbance velocities and accelerations are specifically presented. Subsequently, to investigate the effect of the disturbances on the vibration energy distributions of the FMMB, power flow of the FMMB is exhibited. To verify the dynamic model, an ADAMS physical model of the FMMB is constructed. It reveals that the motion characteristics of the rigid base have a noticeable effect on the vibration responses and power flow of the FMMB and should be considered. The results are significant and contribute to the vibration control of flexible manipulators.

  17. Transport properties and electroanalytical response characteristics of drotaverine ion-selective sensors.

    Kharitonov, Sergey V


    The construction and electroanalytical response characteristics of poly(vinyl chloride) matrix ion-selective sensors (ISSs) for drotaverine hydrochloride are described. The membranes incorporate ion-association complexes of drotaverine with tetraphenylborate, picrate, tetraiodomercurate, tetraiodobismuthate, Reinecke salt, and heteropolycompounds of Keggin structure-molybdophosphoric acid, tungstophosphoric acid, molybdosiliconic acid and tungstosiliconic acid as electroactive materials for ionometric sensor controls. These ISSs have a linear response to drotaverine hydrochloride over the range 8 x 10(-6) to 5 x 10(-2) mol L(-1) with cationic slopes from 51 to 58 mV per concentration decade. These ISSs have a fast response time (up to 1 min), a low determination limit (down to 4.3 x 10(-6) mol L(-1)), good stability (3-5 weeks), and reasonable selectivity. Permeabilities and ion fluxes through a membrane were calculated for major and interfering ions. Dependences of the transport properties of the membranes on the concentrations of the ion exchanger and near-membrane solution and their electrochemical characteristics are presented. The ISSs were used for direct potentiometry and potentiometric titration (sodium tetraphenylborate) of drotaverine hydrochloride. Results with mean accuracy of 99.1+/-1.0% of nominal were obtained which corresponded well to data obtained by use of high-performance liquid chromatography.

  18. Characteristic Functions Describing the Power Absorption Response of Periodic Structures to Partially Coherent Fields

    Craeye, Christophe; Thomas, Christopher N


    Many new types of sensing or imaging surfaces are based on periodic thin films. It is explained how the response of those surfaces to partially coherent fields can be fully characterized by a set of functions in the wavenumber spectrum domain. The theory is developed here for the case of 2D absorbers with TE illumination and arbitrary material properties in the plane of the problem, except for the resistivity which is assumed isotropic. Sum and difference coordinates in both spatial and spectral domains are conveniently used to represent the characteristic functions, which are specialized here to the case of periodic structures. Those functions can be either computed or obtained experimentally. Simulations rely on solvers based on periodic-boundary conditions, while experiments correspond to Energy Absorption Interferometry (EAI), already described in the literature. We derive rules for the convergence of the representation versus the number of characteristic functions used, as well as for the sampling to be ...

  19. Topography of acoustic response characteristics in the midbrain inferior colliculus of Kunming mouse


    Topography of acoustic response characteristics of the midbrain inferior colliculus (IC) of the Kunming mouse was studied by using extracellular recording techniques. The characteristic frequency (CF) range represented in the different divisions of the IC differed markedly: 4-15 kHz in the dorsal cortex (DC), 10-70 kHz in the central nucleus (CN), and 4-35 kHz in the external cortex (EC). The CF in the CN increased from dorsal and lateral to ventral and medial, higher CFs represented at its ventromedial part and lower CFs at its dorsal part. The isofrequency contours of CFs were incurvate. Minimum thresholds (MT) of the auditory neurons in DC and the central part of CN were lower (about 10 dB SPL), but considerably higher in the dorsal and ventral region of EC. Results suggest that each of the divisions in the mouse IC may have different auditory functions.

  20. Acute effects of Dry Immersion on kinematic characteristics of postural corrective responses

    Sayenko, D. G.; Miller, T. F.; Melnik, K. A.; Netreba, A. I.; Khusnutdinova, D. R.; Kitov, V. V.; Tomilovskaya, E. S.; Reschke, M. F.; Gerasimenko, Y. P.; Kozlovskaya, I. B.


    Impairments in balance control are inevitable following exposure to microgravity. However, the role of particular sensory system in postural disorders at different stages of the exposure to microgravity still remains unknown. We used a method called Dry Immersion (DI), as a ground-based model of microgravity, to elucidate the effects of 6-h of load-related afferent inputs on kinematic characteristics of postural corrective responses evoked by pushes to the chest of different intensities during upright standing. The structure of postural corrective responses was altered following exposure to DI, which was manifested by: (1) an increase of the ankle and knee flexion during perturbations of medium intensity, (2) the lack of the compensatory hip extension, as well as diminished knee and ankle flexion with a further increase of the perturbation intensity to submaximal level. We suggest that the lack of weight-bearing increases the reactivity of the balance control system, whereas the ability to scale the responses proportionally to the perturbation intensity decreases. Disrupted neuromuscular coordination of postural corrective responses following DI can be attributed to adaptive neural modifications on the spinal and cortical levels. The present study provides evidence that even a short-term lack of load-related afferent inputs alters kinematic patterns of postural corrective responses, and can result in decreased balance control. Because vestibular input is not primarily affected during the DI exposure, our results indicate that activity and the state of the load-related afferents play critical roles in balance control following real or simulated microgravity.

  1. Stress-Strain of Hotmix Cold Laid Containing Buton Granular Asphat (BGA with Modifier Oil Base and Modifier Water Base as Wearing Course



    Full Text Available Buton granular asphalt (BGA is produced from natural rock asphalt. The employment of hotmix cold laid containing BGA with modifier oil base and modifier oil base can substitute hot rolled asphalt (HRA construction in the remote and distance areas. Natural rock asphalt that deposited in Buton Island, Southeast Sulawesi in Indonesia is crushed to produce Buton granular asphalt (BGA. BGA and cold modifier were utilized to produce hot mixture that can be laid at cold temperature of 50OC to 27OC.The present study provides the information concerning the stress-strain pattern and compressive strength of hotmix cold laid containing BGA and Modifier Oil Base and Modifier Water Base at the storing and compaction time of 4 hours, 3 days and 7 days.

  2. Coupling damage and reliability model of low-cycle fatigue and high energy impact based on the local stress-strain approach

    Chen Hongxia; Chen Yunxia; Yang Zhou


    Fatigue induced products generally bear fatigue loads accompanied by impact processes, which reduces their reliable life rapidly. This paper introduces a reliability assessment model based on a local stress-strain approach considering both low-cycle fatigue and high energy impact loads. Two coupling relationships between fatigue and impact are given with effects of an impact process on fatigue damage and effects of fatigue damage on impact performance. The analysis of the former modifies the fatigue parameters and the Manson-Coffin equation for fatigue life based on material theories. On the other hand, the latter proposes the coupling variables and the difference of fracture toughness caused by accumulative fatigue damage. To form an overall reliability model including both fatigue failure and impact failure, a competing risk model is developed. A case study of an actuator cylinder is given to validate this method.


    周小平; 王建华; 张永兴; 哈秋聆


    The mechanical behavior of rock under uniaxial tensile loading is different from that of rock under compressive loads. A micromechanics-based model was proposed for mesoscopic heterogeneous brittle rock undergoing irreversible changes of their microscopic structures due to microcrack growth. The complete stress-strain relation including linear elasticity, nonlinear hardening,rapid stress drop and strain softening was obtained. The influence of all microcracks with different sizes and orientations were introduced into the constitutive relation by using the probability density function describing the distribution of orientations and the probability density function describing the distribution of sizes. The influence of Weibull distribution describing the distribution of orientations and Rayleigh function describing the distribution of sizes on the constitutive relation were researched. Theoretical predictions have shown to be consistent with the experimental results.

  4. Stress-strain relation of bentonite at undrained shear. Laboratory tests to investigate the influence of material composition and test technique

    Dueck, Ann; Boergesson, Lennart; Johannesson, Lars-Erik (Clay Technology AB, Lund (Sweden))


    This report describes a laboratory study conducted to update the material model of the buffer material used in the analyses of the effect of a rock shear through a deposition hole. The study considers some new conditions and is especially focused on the reference case with MX-80Ca developed for SR-Site (MX-80 ion exchanged to Ca). The material model is based on relations between density, swelling pressure, shear strength and rate of strain. The reference model is described by Boergesson et al. (2010). The laboratory study is focused on undrained stress-strain-strength properties, which have been studied mainly by conducting triaxial tests and unconfined compression tests. The test results are compared to the earlier measurements and models which show that the new results fit very well into the general picture and models. For the new conditions suitable values of constants included in the model are proposed

  5. Analysis of the tensile stress-strain behavior of elastomers at constant strain rates. I - Criteria for separability of the time and strain effects

    Hong, S. D.; Fedors, R. F.; Schwarzl, F.; Moacanin, J.; Landel, R. F.


    A theoretical analysis of the tensile stress-strain relation of elastomers at constant strain rate is presented which shows that the time and the stress effect are separable if the experimental time scale coincides with a segment of the relaxation modulus that can be described by a single power law. It is also shown that time-strain separability is valid if the strain function is linearly proportional to the Cauchy strain, and that when time-strain separability holds, two strain-dependent quantities can be obtained experimentally. In the case where time and strain effect are not separable, superposition can be achieved only by using temperature and strain-dependent shift factors.

  6. Stress-strain relation of bentonite at undrained shear. Laboratory tests to investigate the influence of material composition and test technique

    Dueck, Ann; Boergesson, Lennart; Johannesson, Lars-Erik (Clay Technology AB, Lund (Sweden))


    This report describes a laboratory study conducted to update the material model of the buffer material used in the analyses of the effect of a rock shear through a deposition hole. The study considers some new conditions and is especially focused on the reference case with MX-80Ca developed for SR-Site (MX-80 ion exchanged to Ca). The material model is based on relations between density, swelling pressure, shear strength and rate of strain. The reference model is described by Boergesson et al. (2010). The laboratory study is focused on undrained stress-strain-strength properties, which have been studied mainly by conducting triaxial tests and unconfined compression tests. The test results are compared to the earlier measurements and models which show that the new results fit very well into the general picture and models. For the new conditions suitable values of constants included in the model are proposed

  7. Effect of the load of drive axles and high of the curtain on stress-strain properties of the tractor

    Tomáš Šmerda


    Full Text Available The goal of the experimental measurement was determination of relation among weight load of the tractor together, hitch height changes and drawbar characteristic. The measurement was realized on chassis dynamometer at MUAF in Brno. The first step consisted of rated speed characteristics measurement in conformity with OECD demands. The drawbar characteristic was measured under two selected gears. Adding 980 kg to the nominal wight of the tractor brought increasing maximal drawbar power and drawbar force together with decreasing of slip. The highest differences were observed during the mesurement of fifth gear shifted. The drawbar force grew up to 18.9% as well as the maximal drawbar power (15.2%. The maximal drawbar power at ninth gear gave 62.8 kW. The hitch height was setting to 0.54 m; 0.64 m and 0.74 m. When the hitch height was set from 0.54 m to 0.74 m the drawbar force an power on front axle was lower by reason of load reduction. As can be noticed from the final drawbar characteristics, both curves are identical up to border of maximal drawbar power. Small differences in the area of the highest slips can be ascribed to the rolling resistance.

  8. Photovoltaic Response Characteristics of GaAs Photoconductive Switches Under High Gain Mode

    DAI Hui-ying; SHI Wei


    Given is the experiment results in which the laser pulses of 1 046 nm and 532 nm are used to trigger the semi-insulation GaAs photoconductive semiconductor switch(PCSS) with an electrode distance of 4 mm. And made is an analysis of the switch's photovoltaic response characteristics under the high gain mode when the biased field is bigger than the Geng effect field. Also a theory is presented that the main reason for the photovoltaic pulse response delay is the transmission of charge domain, caused by the presence of EL2 energy level in the chip material. Finally, the transmission time of charge domain is calculated and a result that inosculates with the experiment is attained.

  9. Paradoxical response to an emotional task: trait characteristics and heart-rate dynamics.

    Balocchi, Rita; Varanini, Maurizio; Paoletti, Giulia; Mecacci, Giulio; Santarcangelo, Enrica L


    The present study evaluated the heart-rate dynamics of subjects reporting decreased (responders) or paradoxically increased relaxation (nonresponders) at the end of a threatening movie. Heart-rate dynamics were characterized by indices extracted through recurrence quantification analysis (RQA) and detrended fluctuation analysis (DFA). These indices were studied as a function of a few individual characteristics: hypnotizability, gender, absorption, anxiety, and the activity of the behavioral inhibition and activation systems (BIS/BAS). Results showed that (a) the subjective experience of responsiveness is associated with the activity of the behavioral inhibition system and (b) a few RQA and DFA indices are able to capture the influence of cognitive-emotional traits, including hypnotizability, on the responsiveness to the threatening task.

  10. A comparative study on the uniaxial mechanical properties of the umbilical vein and umbilical artery using different stress-strain definitions.

    Karimi, Alireza; Navidbakhsh, Mahdi


    The umbilical cord is part of the fetus and generally includes one umbilical vein (UV) and two umbilical arteries (UAs). As the saphenous vein and UV are the most commonly used veins for the coronary artery disease treatment as a coronary artery bypass graft (CABG), understating the mechanical properties of UV has a key asset in its performance for CABG. However, there is not only a lack of knowledge on the mechanical properties of UV and UA but there is no agreement as to which stress-strain definition should be implemented to measure their mechanical properties. In this study, the UV and UA samples were removed after caesarean from eight individuals and subjected to a series of tensile testing. Three stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) were employed to determine the linear mechanical properties of UVs and UAs. The nonlinear mechanical behavior of UV/UA was computationally investigated using hyperelastic material models, such as Ogden and Mooney-Rivlin. The results showed that the effect of varying the stress definition on the maximum stress measurements of the UV/UA is significant but not when calculating the elastic modulus. In the true stress-strain diagram, the maximum strain of UV was 92 % higher, while the elastic modulus and maximum stress were 162 and 42 % lower than that of UA. The Mooney-Rivlin material model was designated to represent the nonlinear mechanical behavior of the UV and UA under uniaxial loading.

  11. Imaging Mass Spectrometry by Matrix-Assisted Laser Desorption/Ionization and Stress-Strain Measurements in Iontophoresis Transepithelial Corneal Collagen Cross-Linking

    Paolo Vinciguerra


    Full Text Available Purpose. To compare biomechanical effect, riboflavin penetration and distribution in transepithelial corneal collagen cross-linking with iontophoresis (I-CXL, with standard cross linking (S-CXL and current transepithelial protocol (TE-CXL. Materials and Methods. The study was divided into two different sections, considering, respectively, rabbit and human cadaver corneas. In both sections corneas were divided according to imbibition protocols and irradiation power. Imaging mass spectrometry by matrix-assisted laser desorption/ionization (MALDI-IMS and stress-strain measurements were used. Forty-eight rabbit and twelve human cadaver corneas were evaluated. Results. MALDI-IMS showed a deep riboflavin penetration throughout the corneal layers with I-CXL, with a roughly lower concentration in the deepest layers when compared to S-CXL, whereas with TE-CXL penetration was considerably less. In rabbits, there was a significant increase (by 71.9% and P=0.05 in corneal rigidity after I-CXL, when compared to controls. In humans, corneal rigidity increase was not significantly different among the subgroups. Conclusions. In rabbits, I-CXL induced a significant increase in corneal stiffness as well as better riboflavin penetration when compared to controls and TE-CXL but not to S-CXL. Stress-strain in human corneas did not show significant differences among techniques, possibly because of the small sample size of groups. In conclusion, I-CXL could be a valid alternative to S-CXL for riboflavin delivery in CXL, preserving the epithelium.

  12. Numerical Simulation on the Response Characteristics of a Pneumatic Microactuator for Microfluidic Chips.

    Liu, Xuling; Li, Songjing; Bao, Gang


    This article presents a multiphysical system modeling and simulation of a pneumatic microactuator, which significantly influences the performance of a particular pneumatic microfluidic device. First, the multiphysical system modeling is performed by developing a physical model for each of its three integrated components: microchannel with a microvalve, a gas chamber, and an elastomer membrane. This is done for each step of operation for the whole system. The whole system is then considered a throttle blind capacitor model, and it is used to predict the response time of the pneumatic microactuator by correlating its characteristics such as gas pressurizing, hydraulic resistance, and membrane deformation. For this microactuator, when the maximum membrane deformation is 100 µm, the required actuated air pressure is 80 kPa, and the response time is 1.67 ms when the valve-opening degree is 0.8. The response time is 1.61 ms under fully open conditions. These simulated results are validated by the experimental results of the current and previous work. A correlation between the simulated and experimental results confirms that the multiphysical modeling presented in this work is applicable in developing a proper design of a pneumatic microactuator. Finally, the influencing factors of the response time are discussed and analyzed.

  13. Analysis of Ripple Effects on Frequency Response Characteristics of Switching Regulators

    Sakai, Eiji; Nakahara, Masatoshi

    In this paper we clarify for the boost and the buck-boost converter that the ripple effect is not ignorable for the frequency response, and reveal that it causes the unexpected characteristics where either the phase lag or the phase lead appears depending on the shape of waveform of the ramp generator in the PWM circuit. Eventually the phase margin for the stability drastically changes depending on the slope direction (normal or reverse) of the sawtooth waveform of the ramp generator even in the same circuit configuration. For the ripple effects we propose the general analysis model and analyze them of the boost and the buck-boost converters. As the result we identify that the ripple effects are caused mainly by the variation of the slope and the average of the ripple, and reveal that the both converters have the asymmetric characteristics for the slope direction of the sawtooth waveform of the ramp generator and there is more advantage for the stability in case of the reverse slope direction than in case of the normal one. It also clarified that the effect of ESR of the output capacitor of the converter on the frequency response is different according to the shape of the sawtooth waveforms. The proposed analysis method is validated by the experiments and simulations.

  14. Relationships between Job Stress and Worker Perceived Responsibilities and Job Characteristics

    P Jacobs


    Full Text Available Background: Few studies have examined the relationship between perceived responsibilities by workers and job characteristics and experiences of stress.Objective: To examine the relationship between job stress and work responsibilities and job characteristics.Methods: We analyzed data from 2737 adults who were labor force participants in the province of Alberta, Canada. A logistic regression model was employed to examine factors associated with high job stress.Results: About 18% of the studied workers considered their job as being “highly stressful.” Workers who were male, did not consider their job a career or who were highly satisfied with their jobs were significantly less likely to identify their jobs as “highly stressful.” The probability of describing a job as “highly stressful” significantly increased as workers perceived their actions have an affect on those around them or when their jobs required additional or variable hours.Conclusion: A number of factors are associated with experiencing high work stress including being more engaged with work. This is an important finding for employers, offering insight into where interventions may be targeted.

  15. Certain Type Turbofan Engine Whole Vibration Model with Support Looseness Fault and Casing Response Characteristics

    H. F. Wang


    Full Text Available Support looseness fault is a type of common fault in aeroengine. Serious looseness fault would emerge under larger unbalanced force, which would cause excessive vibration and even lead to rubbing fault, so it is important to analyze and recognize looseness fault effectively. In this paper, based on certain type turbofan engine structural features, a rotor-support-casing whole model for certain type turbofan aeroengine is established. The rotor and casing systems are modeled by means of the finite element beam method; the support systems are modeled by lumped-mass model; the support looseness fault model is also introduced. The coupled system response is obtained by numerical integral method. In this paper, based on the casing acceleration signals, the impact characteristics of symmetrical stiffness and asymmetric stiffness models are analyzed, finding that the looseness fault would lead to the longitudinal asymmetrical characteristics of acceleration time domain wave and the multiple frequency characteristics, which is consistent with the real trial running vibration signals. Asymmetric stiffness looseness model is verified to be fit for aeroengine looseness fault model.

  16. Compressive Behavior and Mechanical Characteristics and Their Application to Stress-Strain Relationship of Steel Fiber-Reinforced Reactive Powder Concrete

    Baek-Il Bae; Hyun-Ki Choi; Bong-Seop Lee; Chang-Hoon Bang


    Although mechanical properties of concrete under uniaxial compression are important to design concrete structure, current design codes or other empirical equations have clear limitation on the prediction of mechanical properties. Various types of fiber-reinforced reactive powder concrete matrix were tested for making more usable and accurate estimation equations for mechanical properties for ultra high strength concrete. Investigated matrix has compressive strength ranged from 30 MPa to 200 M...

  17. Compressive Behavior and Mechanical Characteristics and Their Application to Stress-Strain Relationship of Steel Fiber-Reinforced Reactive Powder Concrete

    Baek-Il Bae; Hyun-Ki Choi; Bong-Seop Lee; Chang-Hoon Bang


    Although mechanical properties of concrete under uniaxial compression are important to design concrete structure, current design codes or other empirical equations have clear limitation on the prediction of mechanical properties. Various types of fiber-reinforced reactive powder concrete matrix were tested for making more usable and accurate estimation equations for mechanical properties for ultra high strength concrete. Investigated matrix has compressive strength ranged from 30 MPa to 200 M...

  18. Characteristics of SIP Response for Rock Specimens in the Gagok Skarn Deposit, Korea

    Kim, C.; Mi Kyung, P.; Park, S.; Shin, S.


    Spectral Induced Polarization (SIP) method was conducted to develop mineral exploration technique in the Gagok skarn deposit, Korea. The Gagok mine was once abandoned and recently reopened. The Gagok stratabound skarn deposit is originated from the Cretaceous granite intrusion into the Paleozoic limestone and slate formations. The ore minerals of the Gagok deposit include sulfide minerals such as sphalerite, pyrrhotite, galena, chalcopyrite, pyrite, arsenopyrite, etc. The characteristics of SIP response for the rock specimens were examined to re-evaluate mineral resources. Total 104 rock specimens were obtained from the mine shafts at the various elevations, and were modified in cylindrical shape for the measurement of SIP response, along with other physical properties such as porosity, density, DC electrical resistivity, magnetic susceptibility, and seismic velocity. The SIP measurement system consists of electrical current transmitter and receiver (model GDP-32 system, Zonge Co. USA), and measures amplitude for resistivity, and phase at 14 steps of frequencies ranging from 0.125 to 1,024 Hz. The results of the SIP measurement shows that the rock specimens from ore bodies accompanied with sulfide minerals such as sphalerite and pyrite produce large phase differences with frequencies applied. The results also show that the rock specimens at the lower elevation of the mine shaft have stronger SIP response and mineralization. The rock specimens with large phase differences of strong SIP response were classified into three phase curve types, based on the range of critical frequency from the SIP measurement. (1) Curve type 1: critical frequency of less than 1 Hz with decreasing phase curve (2) Curve type 2: critical frequency of 1 to 10 Hz with bell shape, (3) Curve type 3: critical frequency of larger than 10 Hz with mixture of curve type 1 and 2. It is believed that the graphitic components and sulfide minerals such as sphalerite and pyrite are dominant in the rock

  19. Clinical Characteristics, Response to Therapy, and Survival of African American Patients Diagnosed With Chronic Lymphocytic Leukemia

    Falchi, Lorenzo; Keating, Michael J.; Wang, Xuemei; Coombs, Catherine C.; Lanasa, Mark C.; Strom, Sara; Wierda, William G.; Ferrajoli, Alessandra


    Background Little is known regarding racial disparities in characteristics and outcomes among patients with chronic lymphocytic leukemia (CLL). Methods The characteristics and outcomes of untreated African American (AA) patients with CLL (n=84) were analyzed and compared with a reference nonblack (NB) patient population (n=1571). Results At the time of presentation, AA patients had lower median hemoglobin levels (12.9 g/dL vs 13.7 g/dL), higher β2 microglobulin levels (2.7 mg/dL vs 2.4 mg/dL), greater frequency of constitutional symptoms (27% vs 10%), unmutated immunoglobulin heavy-chain variable region (IGHV) mutation status (65% vs 47%), ζ-chain-associated protein kinase 70 (ZAP70) expression (58% vs 32%), and deletion of chromosome 17p or chromosome 11q (28% vs 17%; P ≤ 02 for each comparison). Fifty-one percent of AA patients and 39% of NB patients required first-line therapy and 91% and 88%, respectively, received chemoimmunotherapy. Overall response rates to treatment were 85% for AA patients and 94% for NB patients (P=.06); and the complete response rates were 56% and 58%, respectively (P=.87). The median survival of AA patients was shorter compared with that of NB patients (event-free survival: 36 months vs 61 months; P=.007; overall survival: 152 months vs not reached; P=.0001). AA race was an independent predictor of shorter event-free and overall survival in multivariable regression models. Conclusions The current results indicated that AA patients with CLL have more unfavorable prognostic characteristics and shorter survival compared with their NB counterparts. PMID:24022787

  20. [Response characteristics of neurons to tone in dorsal nucleus of the lateral lemniscus of the mouse].

    Si, Wen-Juan; Cheng, Yan-Ling; Yang, Dan-Dan; Wang, Xin


    The dorsal nucleus of lateral lemniscus (DNLL) is a nucleus in the auditory ascending pathway, and casts inhibitory efferent projections to the inferior colliculus. Studies on the DNLL are less than studies on the auditory brain stem and inferior colliculus. To date, there is no information about response characteristics of neurons in DNLL of albino mouse. Under free field conditions, we used extracellular single unit recording to study the acoustic signal characteristics of DNLL neurons in Kunming mice (Mus musculus). Transient (36%) and ongoing (64%) firing patterns were found in 96 DNLL neurons. Neurons with different firing patterns have significant differences in characteristic frequency and minimal threshold. We recorded frequency tuning curves (FTCs) of 87 DNLL neurons. All of the FTCs exhibit an open "V" shape. There is no significant difference in FTCs between transient and ongoing neurons, but among the ongoing neurons, the FTCs of sustained neurons are sharper than those of onset plus sustained neurons and pauser neurons. Our results showed that the characteristic frequency of DNLL neurons of mice was not correlated with depth, supporting the view that the DNLL of mouse has no frequency topological organization through dorsal-ventral plane, which is different from cats and some other animals. Furthermore, by using rate-intensity function (RIF) analysis the mouse DNLL neurons can be classified as monotonic (60%), saturated (31%) and non-monotonic (8%) types. Each RIF type includes transient and ongoing firing patterns. Dynamic range of the transient firing pattern is smaller than that of ongoing firing ones (P transient firing pattern. Multiple firing patterns and intensity coding of DNLL neurons may derive from the projections from multiple auditory nuclei, and play different roles in auditory information processing.

  1. A Canonical Response in Rainfall Characteristics to Global Warming: Projections by IPCC CMIP5 Models

    Lau, William K. M.; Wu, H. T.; Kim, K. M.


    Changes in rainfall characteristics induced by global warming are examined based on probability distribution function (PDF) analysis, from outputs of 14 IPCC (Intergovernmental Panel on Climate Change), CMIP (5th Coupled Model Intercomparison Project) models under various scenarios of increased CO2 emissions. Results show that collectively CMIP5 models project a robust and consistent global and regional rainfall response to CO2 warming. Globally, the models show a 1-3% increase in rainfall per degree rise in temperature, with a canonical response featuring large increase (100-250 %) in frequency of occurrence of very heavy rain, a reduction (5-10%) of moderate rain, and an increase (10-15%) of light rain events. Regionally, even though details vary among models, a majority of the models (>10 out of 14) project a consistent large scale response with more heavy rain events in climatologically wet regions, most pronounced in the Pacific ITCZ and the Asian monsoon. Moderate rain events are found to decrease over extensive regions of the subtropical and extratropical oceans, but increases over the extratropical land regions, and the Southern Oceans. The spatial distribution of light rain resembles that of moderate rain, but mostly with opposite polarity. The majority of the models also show increase in the number of dry events (absence or only trace amount of rain) over subtropical and tropical land regions in both hemispheres. These results suggest that rainfall characteristics are changing and that increased extreme rainfall events and droughts occurrences are connected, as a consequent of a global adjustment of the large scale circulation to global warming.

  2. Speed of response characteristics of goalkeepers: a descriptive and developmental report.

    Sinclair, G D; Moyls, P W


    Photoelectric cells and accelerometers enabled the measurement of reaction, movement and total response times of the limbs of representative goalkeepers (N = 12) from five levels of organized hockey, under simple and choice test conditions. Speed of response characteristics fundamental to success at these levels of competition and the developmental improvement, which must occur annually to permit progress through the goalkeeping hierarchy, were suggested. The point at which the beginner's "reaction-type" pattern of goaltending must be augmented with "anticipation-type" behavior was explored. The concept that the ability to react and move is specific to the direction of the response was upheld at all levels of investigation. Standard deviation of the RT/MT/TRT's of each group reflected the degree of variability of performance that is tolerable at each level. This variability generally decreased with each ascending level within both testing conditions, with the exception of the CRT measures. Data collected over a two year period, for four subjects, revealed that the most evident longitudinal changes occurred in MT and that the youngest player experienced the greatest degree of overall improvement.

  3. Vertical dynamic response characteristics of single pile in non-homogeneous soil layers

    KONG De-sen; LUAN Mao-tian; LING Xian-zhang


    A computational method and a mechanical model for evaluating the vertical dynamic harmonic response characteristics of a single pile embedded in non-homogeneous soil layers and subjected to harmonic loadings were established based on a certain assumption and the improved dynamic model of beam-on-Winkler foundation by using the principle of soil dynamics and structure dynamics. Both non-homogeneity of soil strata and softening effect of soil layer around the pile during vibration were simultaneously taken into account in the pro-posed computational model. It is shown through the comparative study on a numerical example that the numerical results of dynamic response of the single pile computed by the proposed method are relatively rational and can well agree with the numerical results computed from the well-known software of finite element method. Finally the parametric studies were conducted for a varied range of main parameters to discuss the effects of relevant factors on dynamic responses of the single pile embedded in non-homogeneous layered soils excited by harmonic loading with different frequencies.

  4. Study on DFIG wind turbines control strategy for improving frequency response characteristics

    Zhao, Dongmei; Wu, Di; Liu, Yanhua; Zhou, Zhiyu


    The active and reactive power decoupling control for the double-fed induction generator wind turbines(DFIG) does not play a positive role to the frequency response ability of power grid because it performs as the hidden inertia for the power grid. If we want to improve the transient frequency stability of the wind turbine when it is integrated with the system, we must ameliorate its frequency response characteristics. The inability of frequency control due to DFIG decoupling control could be overcome through releasing (or absorbing) a part of the kinetic energy stored in the rotor, so as to increase (or decrease) active power injected to the power system when the deviation of power system frequency appears. This paper discusses the mathematical model of the variable speed DFIG, including the aerodynamic model, pitch control system model, shaft model, generator model and inverter control model, and other key components, focusing on the mathematical model of the converters in rotor side and grid side. Based on the existing model of wind generator, the paper attaches the frequency control model on the platform of the simulation software DIgSILENT/PowerFactory. The simulation results show that the proposed control strategy can response quickly to transient frequency deviation and prove that wind farms can participate in the system frequency regulation to a certain extent. Finally, the result verifies the accuracy and plausibility of the inverter control model which attaches the frequency control module.

  5. Hepatic Histopathological Characteristics and Antioxidant Response of Phytoplanktivorous Silver Carp Intraperitoneally Injected with Extracted Microcystins



    Objectives To investigate the hispathological characteristics and antioxidant responses in liver of silver carp after intraperitoneal administration of microcystins (MCs) for further understanding hepatic intoxication and antioxidation mechanism in fish. Methods Phytoplanktivorous silver carp was injected intraperitoneally (i.p.) with extracted hepatotoxic microcystins (mainly MC-RR and-LR) at a dose of 1000μg MC-LReq./kg body weight, and liver histopathological changes and antioxidant responses were studied at 1, 3, 12, 24, and 48 h, respectively, after injection. Results The damage to liver structure and the activities of hepatic antioxidant enzymes including catalase (CAT), superoxide dismutase (SOD), and ghitathione peroxide (GPX) were increased in a time-dependent manner. Conclusion In terms of clinical and histological signs of intoxication and LD50 (i.p.) dose of MC-LR, silver carp appears rather resistant to MCs exposure than other fishes. Also, the significantly increased SOD activity in the liver of silver carp suggests a higher degree of response to MCs exposure than CAT and GPX.

  6. Sensing Responses Based on Transfer Characteristics of InAs Nanowire Field-Effect Transistors.

    Tseng, Alex C; Lynall, David; Savelyev, Igor; Blumin, Marina; Wang, Shiliang; Ruda, Harry E


    Nanowire-based field-effect transistors (FETs) have demonstrated considerable promise for a new generation of chemical and biological sensors. Indium arsenide (InAs), by virtue of its high electron mobility and intrinsic surface accumulation layer of electrons, holds properties beneficial for creating high performance sensors that can be used in applications such as point-of-care testing for patients diagnosed with chronic diseases. Here, we propose devices based on a parallel configuration of InAs nanowires and investigate sensor responses from measurements of conductance over time and FET characteristics. The devices were tested in controlled concentrations of vapour containing acetic acid, 2-butanone and methanol. After adsorption of analyte molecules, trends in the transient current and transfer curves are correlated with the nature of the surface interaction. Specifically, we observed proportionality between acetic acid concentration and relative conductance change, off current and surface charge density extracted from subthreshold behaviour. We suggest the origin of the sensing response to acetic acid as a two-part, reversible acid-base and redox reaction between acetic acid, InAs and its native oxide that forms slow, donor-like states at the nanowire surface. We further describe a simple model that is able to distinguish the occurrence of physical versus chemical adsorption by comparing the values of the extracted surface charge density. These studies demonstrate that InAs nanowires can produce a multitude of sensor responses for the purpose of developing next generation, multi-dimensional sensor applications.

  7. Investigations on surface quality characteristics with multi-response parametric optimization and correlations

    Amlana Panda


    Full Text Available This paper presents the parametric optimization on surface quality characteristics (Ra, Rz and Rt in hard turning of EN31 steel using multilayer coated carbide insert (TiN/TiCN/Al2O3 and also finds correlations. The experiments have been conducted based on Taguchi’s L9 orthogonal array. Multiple linear regression analysis has been utilized to find the correlations. The integrated multi-response optimization approach using CQL concept in WPCA coupled with Taguchi technique has been implemented. Based on the S/N ratio, the optimal process parameters for surface roughness i.e. Ra and Rz are the depth of cut at level 3 (0.5 mm, the cutting speed at level 3 (140 m/min, and the feed at level 1 (0.04 mm/rev. The optimal process parameters for Rt are found to be the depth of cut at level 3 (0.5 mm, the cutting speed at level 2 (100 m/min, and the feed at level 1 (0.04 mm/rev. Feed and depth of cut are found to be the significant cutting parameters affecting the responses at 95% confidence limit from ANOVA study. The first order model presented high correlation coefficient between the experimental and predicted values. The optimal parametric combination for multi-response (Ra, Rz and Rt becomes d3–v3–f1 and is greatly improved.

  8. Characteristics of electroencephalographic responses induced by a pleasant and an unpleasant odor.

    Kim, Yeon-Kyu; Watanuki, Shigeki


    More than sensory stimuli, odorous stimuli were employed to facilitate the evocation of emotional responses in the present study. The odor-stimulated emotion was evaluated by investigating specific features of encephalographic (EEG) responses produced thereof. In this study, the concentrations of the same odor were altered; viz., the changes in odor-induced emotional level were compared with the concurrently monitored EEG response features. In addition, we performed the mental task to evoke the arousal state of the brain and investigated the resemblance of response characteristics of the resting state to the post-mental task resting state. Subjects having no abnormalities in the sense of smell included 12 male undergraduate and graduate students (age range: 22-26 years). Experiment I involved 2 types of odors that induced favorable odorous stimuli (pleasant induction); test-solutions were either diluted 150 (easily perceptible odorous sensation) or 500 (slightly perceptible odorous stimuli) times. Experiment II had 2 types of odors that evoked unfavorable odorous stimuli (unpleasant induction), and test-solutions with dilution rates similar to those of pleasant induction were prepared. Odorless distilled water was used as the control in both experiments. From results of rating the odorous stimuli of our compounds used, the candidates were respectively found to be appropriate in inducing the pleasant and unpleasant smell sensations. The analyses of EEG responses on inducing pleasant and unpleasant smell sensations revealed that the EEG activities of the left frontal region were enhanced. This finding may establish the hypothesis of a relationship prevailing between the positive approach-related emotion evoked by the visual sensation and the left hemisphere (Davidson, 1992; Tomarken et al., 1989). In other words, it can be interpreted that the negative withdrawal-related emotion may be associated with activities of the right hemisphere. However, this hypothesis may

  9. Temporal characteristics of gustatory responses in rat parabrachial neurons vary by stimulus and chemosensitive neuron type.

    Geran, Laura; Travers, Susan


    It has been demonstrated that temporal features of spike trains can increase the amount of information available for gustatory processing. However, the nature of these temporal characteristics and their relationship to different taste qualities and neuron types are not well-defined. The present study analyzed the time course of taste responses from parabrachial (PBN) neurons elicited by multiple applications of "sweet" (sucrose), "salty" (NaCl), "sour" (citric acid), and "bitter" (quinine and cycloheximide) stimuli in an acute preparation. Time course varied significantly by taste stimulus and best-stimulus classification. Across neurons, the ensemble code for the three electrolytes was similar initially but quinine diverged from NaCl and acid during the second 500 ms of stimulation and all four qualities became distinct just after 1s. This temporal evolution was reflected in significantly broader tuning during the initial response. Metric space analyses of quality discrimination by individual neurons showed that increases in information (H) afforded by temporal factors was usually explained by differences in rate envelope, which had a greater impact during the initial 2s (22.5% increase in H) compared to the later response (9.5%). Moreover, timing had a differential impact according to cell type, with between-quality discrimination in neurons activated maximally by NaCl or citric acid most affected. Timing was also found to dramatically improve within-quality discrimination (80% increase in H) in neurons that responded optimally to bitter stimuli (B-best). Spikes from B-best neurons were also more likely to occur in bursts. These findings suggest that among PBN taste neurons, time-dependent increases in mutual information can arise from stimulus- and neuron-specific differences in response envelope during the initial dynamic period. A stable rate code predominates in later epochs.

  10. Clinical characteristics and treatment response to SSRI in a female pedophile.

    Chow, Eva W C; Choy, Alberto L


    Although much investigation has been done with male sex offenders, there have been few studies on female sex offenders. Female sex offenders have been reported as having a high incidence of psychiatric disorders, but female paraphilics were rarely described. The literature on the treatment of female sex offenders is also limited and treatment with a selective serotonin reuptake inhibitor (SSRI) has not been reported. This paper presents the case of a woman with DSM-IV pedophilia. Her clinical characteristics, her offense history, and her positive response to treatment with sertraline (a SSRI) are described. This case adds to the limited literature on female pedophiles and suggests that SSRIs may be an effective treatment for paraphilic disorders in female sex offenders.

  11. CHARADE: A characteristic code for calculating rate-dependent shock-wave response

    Johnson, J.N.; Tonks, D.L.


    In this report we apply spatially one-dimensional methods and simple shock-tracking techniques to the solution of rate-dependent material response under flat-plate-impact conditions. This method of solution eliminates potential confusion of material dissipation with artificial dissipative effects inherent in finite-difference codes, and thus lends itself to accurate calculation of elastic-plastic deformation, shock-to-detonation transition in solid explosives, and shock-induced structural phase transformation. Equations are presented for rate-dependent thermoelastic-plastic deformation for (100) planar shock-wave propagation in materials of cubic symmetry (or higher). Specific numerical calculations are presented for polycrystalline copper using the mechanical threshold stress model of Follansbee and Kocks with transition to dislocation drag. A listing of the CHARADE (for characteristic rate dependence) code and sample input deck are given. 26 refs., 11 figs.

  12. Topography of acoustic response characteristics in the auditory cortex of the Kunming mouse


    Topography of acoustic response characteristics in the auditory cortex (AC) of the Kunming (KM) mouse has been examined by using microelectrode recording techniques.Based on best-frequency (BF) maps,both the primary auditory field (AⅠ) and the anterior auditory field (AAF) are tonotopically organized with a counter running frequency gradient.Within an isofrequency stripe,the width of the frequency-threshold curves of single neurons increases,and minimum threshold (MT) decreases towards more ventral locations.BFs in AⅠand AAF range from 4 to 38 kHz.Auditory neurons with BFs above 40 kHz are located at the rostrodorsal part of the AC.The findings suggest that the KM mouse is a good model suitable for auditory research.

  13. Statistical modeling of the response characteristics of mechanosensitive stimuli in the human esophagus

    Drewes, Asbjørn Mohr; Reddy, Hari Prasad; Ståhl, Camilla


    It is believed that mechanical stimuli of the human gut activate afferents responding to either noxious or normal, physiologic stimuli. They might be able to sensitize without relation to the contractile state of the smooth muscle. The current study aimed to verify the above characteristics by us...... of mechanical gut stimuli in human beings. This might increase our understanding of visceral pain in health and disease and guide the statistical analysis of experimental data obtained in the gastrointestinal tract....... by using a statistical model based on correlation analysis. The esophagus was distended with a bag in 32 healthy subjects by using an inflation rate of 25 mL/min. The luminal cross-sectional areas and sensory ratings were determined during the distentions. The stimuli were repeated after relaxation...... esophagus are not correlated and thus probably represent different populations. The response characteristics have no physiologic relationship to the contractile state of the smooth muscle, and sensitization affects all types of afferents. Perspectives The article adds information about sensory processing...

  14. Response of Stream Pollution Characteristics to Catchment Land Cover in Cao-E River Basin, China

    SHEN Ye-Na; L(U) Jun; CHEN Ding-Jiang; SHI Yi-Ming


    This study addressed the relationship of river water pollution characteristics to land covers and human activities in the catchments in a complete river system named Cao-E River in eastcrn China. Based on the hydrogsochemical data collected monthly over a period of 3 years, cluster analysis (CA) and principal component analysis (PCA) were adopted to categorize the river reaches and reveal their pollution characteristics. According to the differences of water quality in the river reaches and land use patterns and average population densities in their catchments, the whole river system could be categorized into three groups of river reaches, i.e., non-point sources pollution reaches (NPSPR), urban reaches (UR) and mixed sources pollution reaches (MSPR). In UR and MSPR, the water quality was mainly impacted by nutrient and organic pollution, while in NPSPR nutrient pollution was the main cause. The nitrate was the main nitrogen form in NPSPR and particulate phosphorus was the main phosphorus form in MSPR. There were no apparent trends for the variations of pollutant concentrations with increasing river flows in NPSPR and MSPR, while in UR the pollutant concentrations decreased with increasing river flows. Thus dry season was the critical period for water pollution control in UR. Therefore, catchment land covers and human activities had significant impact on river reach water pollution type, nutrient forms and water quality responses to hydrological conditions, which might be crucial for developing strategies to combat water pollution in watershed scale.

  15. Frequency characteristic of response of surface air pressure to changes in flux of cosmic rays

    Bogdanov, M. B.


    We compare the series of daily-average values of the surface air pressure for De Bilt and Lugano meteorological stations with subtracted linear trends and seasonal harmonics, as well as the series of the flux of galactic cosmic rays (GCRs) at Jungfraujoch station with subtracted moving average over 200 days. Using the method of superposed epochs, we show that the Forbush decreases at both stations are accompanied by increased pressure. Spectral analysis allows us to conclude that the analyzed series are characterized by nonzero coherence in almost the entire frequency range: from 0.02 day-1 day up to the Nyquist frequency of 0.5 day-1. Using changes in the GCR flux as a probing signal, we obtain amplitude-frequency characteristics of the pressure reaction. For both stations, these characteristics are in qualitative agreement with each other and indicate that the atmospheric response can be described by a second-order linear dynamic system that has wide resonance with a maximum at a frequency of 0.15 day-1.

  16. Stimulus-response characteristics of motor evoked potentials and silent periods in proximal and distal upper-extremity muscles.

    Kuijk, A.A. van; Anker, L.C.; Pasman, J.W.; Hendriks, J.C.M.; Elswijk, G.A.F. van; Geurts, A.C.H.


    OBJECTIVE: To compare stimulus-response characteristics of both motor evoked potentials (MEP) and silent periods (SP) induced by transcranial magnetic stimulation (TMS) in proximal and distal upper-extremity muscles. METHODS: Stimulus-response curves of MEPs and SPs were obtained from the biceps bra

  17. Stimulus-response characteristics of motor evoked potentials and silent periods in proximal and distal upper-extremity muscles.

    Kuijk, A.A. van; Anker, L.C.; Pasman, J.W.; Hendriks, J.C.M.; Elswijk, G.A.F. van; Geurts, A.C.H.


    OBJECTIVE: To compare stimulus-response characteristics of both motor evoked potentials (MEP) and silent periods (SP) induced by transcranial magnetic stimulation (TMS) in proximal and distal upper-extremity muscles. METHODS: Stimulus-response curves of MEPs and SPs were obtained from the biceps bra


    Yan Xianguo; Guan Huiling; Zhang Youyun


    Based on the beginning, propagating and ending mechanism of rotating-stall cell, the relation between the pressure history signal and the pressure distribution along rotor circumference is proposed.The angular velocities of rotating-stall cell propagating are computed from time series picked by the pressure probes on a cross section.Self-relation calculating filtered the random noise of the pressure history data.The exciting load on rotor is computed by integral of filtered pressure signal along rotor circumference.By Prohl-Myklestad method, dynamical equations of rotor system are obtained.The dynamical response of rotor system is resolved by using Matlab system.Further more, the situation of more than one of stall cells is discussed.Two cases respectively from the natural gas compressor of some fertilizer plant and the CO2 compressor of some nitrogenous fertilizer plant demonstrate that both methods of calculating the load exerted on rotor by pressure fluctuation and resolving the dynamic response of rotor are available and the characteristics of frequency spectrum of rotating stall are correct.

  19. Eco-physiological Characteristics of Alfalfa Seedlings in Response to Various Mixed Salt-alkaline Stresses


    Soil salinization and alkalization frequently co-occur in nature, but little is known about the mixed effects of salt-alkaline stresses on plants. An experiment with mixed salts (NaCl, Na2SO4, NaHCO3 and Na2CO3) and 30 salt-alkaline combinations(salinity 24-120 mmol/L and pH 7.03-10.32) treating Medicago sativa seedlings was conducted. The results demonstrated that salinity and alkalinity significantly affected total biomass and biomass components of seedlings. There were interactive effects of salt composition and concentration on biomass (P ≤ 0.001). The interactions between salinity and alkalinity stresses led to changes in the root activity along the salinity gradient (P ≤ 0.001). The effects of alkalinity on seedling survival rate were more significant than those of salinity, and the seedlings demonstrated some physiological responses(leaf electrolyte leakage rate and proline content) in order to adapt to mixed salt-alkaline stresses. It was concluded that the mixed salt-alkaline stresses, which differ from either salt or alkali stress, emphasize the significant interaction between salt concentration (salinity) and salt component (alkalinity). Further, the effects of the interaction between high alkalinity and salinity are more severe than those of either salt or alkali stress, and such a cooperative interaction results in more sensitive responses of ecological and physiological characteristics in plants.

  20. Boundary spanning by nurse managers: effects of managers' characteristics and scope of responsibility on teamwork.

    Meyer, Raquel M; O'Brien-Pallas, Linda; Doran, Diane; Streiner, David; Ferguson-Paré, Mary; Duffield, Christine


    Increasing role complexity has intensified the work of managers in supporting healthcare teams. This study examined the influence of front-line managers' characteristics and scope of responsibility on teamwork. Scope of responsibility considers the breadth of the manager's role. A descriptive, correlational design was used to collect cross-sectional survey and administrative data in four acute care hospitals. A convenience sample of 754 staff completed the Relational Coordination Scale as a measure of teamwork that focuses on the quality of communication and relationships. Nurses (73.9%), allied health professionals (14.7%) and unregulated staff (11.7%) worked in 54 clinical areas, clustered under 30 front-line managers. Data were analyzed using hierarchical linear modelling. Leadership practices, clinical support roles and compressed operational hours had positive effects on teamwork. Numbers of non-direct report staff and areas assigned had negative effects on teamwork. Teamwork did not vary by span, managerial experience, worked hours, occupational diversity or proportion of full-time employees. Large, acute care teaching hospitals can enable managers to foster teamwork by enhancing managers' leadership practices, redesigning the flow or reporting structure for non-direct reports, optimizing managerial hours relative to operational hours, allocating clinical support roles, reducing number of areas assigned and, potentially, introducing co-manager models.

  1. Orientation dependency of shear stress-strain curves in B2-ordered Fe3Al single crystals deformed in tension at room temperature

    郑为为; 杨王玥; 孙祖庆


    B2-ordered Fe3Al single crystals with various orientations were deformed in tension at room temperature in vacuum. The shape of shear stress-strain curves and work hardening rates were found to be strongly dependent on the orientation. The formation of the five different work hardening stages were considered to be related to the number of operative slip systems, the effect of secondary slip systems and the dissociation of the twofold superdislocation. Stage I is an easy glide stage corresponding to single slip. Stage II, with high hardening rate, often corresponds to the existence of conjugate slip systems. Stage III, with relatively low hardening rate, corresponds to the weaker hardening of secondary slip systems. Stage IV, with the highest hardening rate, is not only related to multiple slip but also the dissociation of twofold superdislocations and the moving of superpartials with an antiphase boundary (APB) trap. Stages V, with a negative hardening rate, may be caused by the cross slip of single dissociated superdislocation. The number of stages and the work hardening rate of the same stage were also found to change significantly, when the tensile orientation lies in different orientation regions.

  2. Finite Element Model to Analyze an Installation Load-based Stress-Strain State of the Parts Forming Gas Joint of a Medium-Speed Diesel Engine

    N. D. Chainov


    Full Text Available The paper considers a developed computational model to study a stress-strain state of the assembly unit components of a medium-speed diesel engine of new generation, type CH26.5/31, which comprises a cylinder head, a sleeve, a gasket, a block, two mounting studs and four power studs.The developed three-dimensional finite element model presented in this article allows us to take into consideration all the components that make up a gas joint, regardless of their geometric complexity. Its use enables us to estimate the cylinder head - gasket - sleeve tightness of sealing when applying the mounting, temperature, and gas loads, to define the stress and strain components of parts, as well as to study the gasket condition, including pressure distribution across its surface.Based on the results obtained in the study the finite element model of the cylinder head was modified considering a more detailed description of its geometry, thus reducing the principal tensile stresses.

  3. Contrast in stress-strain history during exhumation between high- and ultrahigh-pressure metamorphic units in the Western Alps: Microboudinage analysis of piemontite in metacherts

    Omori, Yasutomo; Barresi, Antonello; Kimura, Nozomi; Okamoto, Atsushi; Masuda, Toshiaki


    Our analyses of microboudinage structures of piemontite grains embedded within six samples of metachert, one collected from an ultrahigh-pressure (UHP) metamorphic unit at Lago di Cignana in Italy of the Western Alps, and the other five from surrounding high-pressure (HP) metamorphic units in Italy and France, have revealed that the structures are all symmetrical in type, and were presumably produced in coaxial strain fields. Stress-strain analyses of the microboudinaged grains revealed significant contrasts in the stress and strain histories of the UHP and HP metamorphic units, with the differential stress recorded by the UHP sample being unequivocally lower than that recorded by the five HP samples. In addition, our analyses showed that the UHP sample underwent stress-relaxation during microboudinage, whereas the five HP samples did not. On the basis of these observations and analyses we discuss the mechanical decoupling of the UHP and HP units that led to different histories in differential stress between the units during exhumation of the Western Alps.

  4. A Modified Johnson-Cook Model to Predict Stress-strain Curves of Boron Steel Sheets at Elevated and Cooling Temperatures

    Duc-Toan, Nguyen; Tien-Long, Banh; Dong-Won, Jung; Seung-Han, Yang; Young-Suk, Kim


    In order to predict correctly stress-strain curve for tensile tests at elevated and cooling temperatures, a modification of a Johnson-Cook (J-C) model and a new method to determine (J-C) material parameters are proposed. A MATLAB tool is used to determine material parameters by fitting a curve to follow Ludwick and Voce's hardening law at various elevated temperatures. Those hardening law parameters are then utilized to determine modified (J-C) model material parameters. The modified (J-C) model shows the better prediction compared to the conventional one. An FEM tensile test simulation based on the isotropic hardening model for metal sheet at elevated temperatures was carried out via a user-material subroutine, using an explicit finite element code. The simulation results at elevated temperatures were firstly presented and then compared with the measurements. The temperature decrease of all elements due to the air cooling process was then calculated when considering the modified (J-C) model and coded to VUMAT subroutine for tensile test simulation. The modified (J-C) model showed the good comparability between the simulation results and the corresponding experiments.

  5. A Modified Johnson-Cook Model for Sheet Metal Forming at Elevated Temperatures and Its Application for Cooled Stress-Strain Curve and Spring-Back Prediction

    Duc-Toan, Nguyen; Tien-Long, Banh; Young-Suk, Kim; Dong-Won, Jung


    In this study, a modified Johnson-Cook (J-C) model and an innovated method to determine (J-C) material parameters are proposed to predict more correctly stress-strain curve for tensile tests in elevated temperatures. A MATLAB tool is used to determine material parameters by fitting a curve to follow Ludwick's hardening law at various elevated temperatures. Those hardening law parameters are then utilized to determine modified (J-C) model material parameters. The modified (J-C) model shows the better prediction compared to the conventional one. As the first verification, an FEM tensile test simulation based on the isotropic hardening model for boron sheet steel at elevated temperatures was carried out via a user-material subroutine, using an explicit finite element code, and compared with the measurements. The temperature decrease of all elements due to the air cooling process was then calculated when considering the modified (J-C) model and coded to VUMAT subroutine for tensile test simulation of cooling process. The modified (J-C) model showed the good agreement between the simulation results and the corresponding experiments. The second investigation was applied for V-bending spring-back prediction of magnesium alloy sheets at elevated temperatures. Here, the combination of proposed J-C model with modified hardening law considering the unusual plastic behaviour for magnesium alloy sheet was adopted for FEM simulation of V-bending spring-back prediction and shown the good comparability with corresponding experiments.

  6. Fractal-based modeling of the stress-strain relation of Bi2Sr2CaCu2Ox/AgMg superconducting round wires

    Gou, Xiaofan; Schwartz, Justin


    Bi2Sr2CaCu2Ox/AgMg (Bi2212) multi filamentary superconducting round wires (RWs) can be only potential candidate for constructing the superconducting magnet with higher magnetic field (>25T). Very complicated microstructure of Bi2212 RWs has been found by recent SEM studies, and then the vital problems of Characterization of this unique microstructure and further exploration of the correlation of macro electromechanical properties with this microstructure arise. In this paper, it is firstly found that the rough surface of individual filaments can be well characterized by fractals. On the geometrical model with the fractal simulation of the rough surface, stress-strain relation of Bi2212 RWs has been investigated. The modelling result with considering the rough surface has a better agreement to the experimental data. At the request of the authors, and with the agreement of the Proceedings Editor, the above paper in AIP Proceedings has been retracted (as of 26 November 2013) due to a prior publication by the authors which reports similar data/results. That paper was first published in volume 26 (issue 5) of the journal Superconductor Science and Technology and was published on 4 April 2013: Fractal analysis of the role of the rough interface between Bi2Sr2CaCu2Ox filaments and the Ag matrix in the mechanical behavior of composite round wires The authors wish to apologize for any inconvenience caused by publication of their AIP Proceedings article.

  7. Dependence of the cyclic stress-strain curve on loading history and its interaction with fatigue of 304L stainless steel

    Belattar, Adel, E-mail: [INSA Rouen/GPM, UMR CNRS 6634, BP 08, Avenue de l' Universite, 76800 St. Etienne du Rouvray (France); Taleb, Lakhdar; Hauet, Annie [INSA Rouen/GPM, UMR CNRS 6634, BP 08, Avenue de l' Universite, 76800 St. Etienne du Rouvray (France); Taheri, Said [LaMSID UMR EDF-CNRS 2832, Department AMA, 1 Avenue du General de Gaulle, 92141 Clamart Cedex (France)


    Highlights: Black-Right-Pointing-Pointer Contrary to low deformation, cyclic curve is not unique at high strain amplitude. Black-Right-Pointing-Pointer However, as the loading was continued cyclic hardening tends to stabilize. Black-Right-Pointing-Pointer Cyclic hardening is mainly kinematic type, isotropic component remains quasi-linear. Black-Right-Pointing-Pointer Increasing in pre-hardening strain amplitude has almost no effect on fatigue damage. Black-Right-Pointing-Pointer Fatigue life decreasing is associated with formation of walls, cells and defect bands. - Abstract: This study investigates the effects of loading history on the cyclic stress-strain curve and fatigue behavior of 304L stainless steel at room temperature. Tension-compression tests were performed on the same specimen under controlled strain, using several loading sequences of increasing or decreasing amplitude. The results show that the cyclic curve is not unique, as it depends on the loading sequence. The same predeformed specimens were subjected to fatigue tests. The results showed that fatigue life is significantly reduced by the previous loading history. A previously developed method for determining the effect of prehardening was evaluated. Microstructural analyses were also performed; the microstructures after preloading and their evolution during the fatigue cycles were characterized by transmission electron microscopy (TEM). The results of these analyses improve our understanding of the macroscopic properties of 304L stainless steel and can help us identify the causes of failure and lifetime reduction.

  8. Determination of the stress-strain curve in specimens of Scots pine for numerical simulation of defect free beams

    Baño, V.


    Full Text Available The objective of this paper is to develop a twodimensional numerical model to simulate the response of Scots pine (Pinus sylvestris L. defect free timber members in order to predict the behaviour of these members when subjected to external forces. For this purpose, data of the mechanical properties of Scots pine were obtained by performing experimental tests on specimens. We determined the stresses and deformations of timber beams in the elastic-plastic and plastic phases. In addition, we developed a finite element software that considered the orthotropic nature of timber, the non-linearity of the compression-reduction branch and the differing moduli of elasticity in tension and compression for Scots pine beams free from defects. The software developed simulates an experimental four point bending test according to UNE-EN 408 Standard.

    El objetivo de este trabajo es el desarrollo de un modelo numérico bidimensional de piezas de madera de Pinus sylvestris L. libre de defectos que prediga su comportamiento frente a solicitaciones externas. Para su desarrollo, fue necesario realizar ensayos experimentales sobre probetas de pequeño tamaño con el fin de obtener los datos de las propiedades mecánicas para el Pinus sylvestris L. de procedencia española. A partir de los datos experimentales obtenidos, se desarrolla un programa de elementos finitos que considera la ortotropía de la madera, la no linealidad de la rama compresión-acortamiento y los distintos módulos de elasticidad a tracción y a compresión para vigas libres de defectos. El programa simula el ensayo experimental de flexión en cuatro puntos según la Norma UNE-EN 408 y aborda la determinación de las tensiones y deformaciones de las vigas de madera en las tres fases de comportamiento: elástica, elastoplástica y plástica.

  9. Variation of Floods Characteristics and Their Responses to Climate and Human Activities in Poyang Lake, China

    LI Xianghu; ZHANG Qi


    The Poyang Lake is one of the most frequently flooded areas in China.Understanding the changing characteristics of floods as well as the affecting factors is an important prerequisite of flood disaster prevention and mitigation.The present study identified the characteristics variations of historical floods in the Poyang Lake and their tendencies based on the Mann-Kendall (M-K) test,and also investigated the related affecting factors,both from climate and human activities.The results revealed that the highest flood stages,duration as well as hazard coefficient of floods showed a long-term increasing linear trend during the last 60 years with the M-K statistic of 1.49,1.60 and 1.50,respectively.And,a slightly increasing linear trend in the timing of the highest stages indicated the floods occurred later and later during the last six decades.The rainfall during the flood season and subsequent discharges of the Changjiang (Yangtze) River and runoff from the Poyang Lake Basin were mainly responsible for the severe flood situation in the Poyang Lake in the 1990s.In addition,the intensive human activities,including land reclamation and levee construction,also played a supplementary role in increasing severity of major floods.While,the fewer floods in the Poyang Lake after 2000 can be attributed to not only the less rainfall over the Poyang Lake Basin and low discharges of the Changjiang River during flood periods,but also the stronger influences of human activity which increased the floodwater storage of the Poyang Lake than before.

  10. Prenatal reporting to child protection: Characteristics and service responses in one Australian jurisdiction.

    Taplin, Stephanie


    Prenatal reporting to child protection services has been enacted into most jurisdictions across Australia and in other countries, its aims being to intervene early and provide supports which will either identify or prevent the need for a baby to be taken into care and protection once born. Despite indications that there are increasing numbers of prenatal reports, little is known about the characteristics of those reported, the timing and reasons for reports, service responses, and the impacts of being reported. This study is one of the first to use administrative data to examine the characteristics of two samples from one Australian jurisdiction: (i) data from casefiles of 38 cases reported in 2012-13, and (ii) administrative data from 117 cases reported prenatally in 2013. These data showed that women who were reported to child protection services in relation to their pregnancy were predominantly disadvantaged, and were likely to be reported relatively late in their pregnancy due to 'future risk concerns'. Approximately two-thirds of those reported were provided with some prenatal support, as recorded by the child protection system, generally of limited duration. Twelve percent of the babies born to the larger cohort of women were removed within 100days of their birth. It is likely that longer term supportive interventions are needed, to reduce the risk factors evident in women reported during pregnancy, and to improve their ability to safely care for their children. Information on the short and long-term impacts from rigorous evaluations and longer-term intervention trials are also vital to ensure that prenatal reporting and interventions are, in fact, improving outcomes for infants and families.

  11. Simultaneous idiopathic bilateral sudden hearing loss - characteristics and response to treatment.

    Akil, Ferit; Yollu, Umur; Yilmaz, Mehmet; Yener, H Murat; Mamanov, Marlen; Inci, Ender


    The aetiology of sudden hearing loss is poorly defined; however, infectious, vascular and neoplastic aetiologies are presumed to be responsible. In addition, the aetiology of bilateral sudden hearing loss is also unknown. The objective of this study is identify the characteristics and treatment response of simultaneous bilateral sudden hearing loss. This is a case-control study that practised in tertiary care academic centre. 132 patients with sudden hearing loss who were treated with systemic steroid and hyperbaric oxygen together were included. 26 patients had bilateral sudden hearing loss and 106 patients had unilateral sudden hearing loss. Patients were evaluated with clinical, audiological and radiological examinations and laboratory tests were done. Findings and response to treatment of the patients were compared. The mean ages of patients with unilateral and bilateral sudden hearing loss were 42.0 years and 24.5 years respectively with a statistically significant difference (psudden hearing loss. Pre-treatment audiologic thresholds were 69.1dB for unilateral sudden hearing loss and 63.3dB for the left ears and 67.6dB for the right ears for bilateral sudden hearing loss without significant difference. Post-treatment average hearing threshold in unilateral sudden hearing loss was 47.0dB and 55.4dB for the left ears and 59.0 for the right ears in bilateral sudden hearing loss. Average hearing improvement in unilateral sudden hearing loss group was significant (psudden hearing loss group for both ears. Between the groups; there was a significant difference for hearing improvement favouring unilateral sudden hearing loss (psudden hearing loss showed lower age, worse prognosis and higher rate of positive immune response markers. Cardiovascular risk factors seem to have an important role in the aetiology of unilateral cases whereas this importance was not present in bilateral ones. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia C

  12. Macrocyclic compound as ionophores in lead(Ⅱ)ion-selective electrodes with excellent response characteristics

    HUANG MeiRong; MA XiaoLi; LI XinGui


    Macrocyclic compounds, such as crown ethers, azacrown ethers, thiacrown ethers, calixarenes and porphyrins, which act as ionophores in lead(Ⅱ) ion-selective electrodes, are systematically summarized based on the latest literatures. The molecular structure characteristics of the ionophores are general-ized. The modification regulations for the substituted ionophores are elaborated with the purpose ofimproving the response features of the lead(Ⅱ) ion-selective electrodes assembled by them. It is pointed out that the introduction of pendant moieties which contain soft base coordination centers like N, S and P atoms is in favor of adjusting the cavity size and conformation of the macrocyclic com-pounds. Furthermore, there is synergic effect between the cavity and the donor sites of the ligand and thus the selective complexation of lead ions is easily realized, resulting in significant avoidance of the interference from other metal ions. The macrocyclic ionophore having the best response characteris-tics thus far was found to be N,N'-dimethylcyanodiaza-18-crown-6 with the detection limit of 7.0×10-8 (14.5 μg/L), which is one of the uncommon ionophores that can really eliminate the interference from silver and mercury ions. The selectivity coefficients of the ionophore for lead ions over other metal ions, such as alkali, alkaline earth and transition metal ions are in the order of 10-4 or smaller, where the se-lectivity coefficient of lead(Ⅱ) over mercury(Ⅱ) ions is much lower, down to 8.9×10-4. The structure de-sign idea for high-performance ionophore is proposed according to present results. The incorporation of nitrogen atom, especially cyano group or thiocyano group or amino/imino groups, rather than thio atom alone could result in new excellent lead ionophores. The aborative design for metacyclophanes containing aromatic nitrogen atoms with the aim of creating excellent ionophores would also become a potential research trend. The lead(Ⅱ) ion

  13. Characteristics of the nuclear magnetic resonance logging response in fracture oil and gas reservoirs

    Xiao Lizhi; Li Kui, E-mail: [State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249 (China)


    Fracture oil and gas reservoirs exist in large numbers. The accurate logging evaluation of fracture reservoirs has puzzled petroleum geologists for a long time. Nuclear magnetic resonance (NMR) logging is an effective new technology for borehole measurement and formation evaluation. It has been widely applied in non-fracture reservoirs, and good results have been obtained. But its application in fracture reservoirs has rarely been reported in the literature. This paper studies systematically the impact of fracture parameters (width, number, angle, etc), the instrument parameter (antenna length) and the borehole condition (type of drilling fluid) on NMR logging by establishing the equation of the NMR logging response in fracture reservoirs. First, the relationship between the transverse relaxation time of fluid-saturated fracture and fracture aperture in the condition of different transverse surface relaxation rates was analyzed; then, the impact of the fracture aperture, dip angle, length of two kinds of antennas and mud type was calculated through forward modeling and inversion. The results show that the existence of fractures affects the NMR logging; the characteristics of the NMR logging response become more obvious with increasing fracture aperture and number of fractures. It is also found that T{sub 2} distribution from the fracture reservoir will be affected by echo spacing, type of drilling fluids and length of antennas. A long echo spacing is more sensitive to the type of drilling fluid. A short antenna is more effective for identifying fractures. In addition, the impact of fracture dip angle on NMR logging is affected by the antenna length.

  14. Biological characteristics of the cerebral venous system and its hemodynamic response to intracranial hypertension

    CHEN Jie; WANG Xi-ming; LUAN Li-ming; CHAO Bao-ting; PANG Bo; SONG Hui; PANG Qi


    Background The role of the cerebral venous system (CVS) in intracranial pressure (ICP) regulation remains largely unclear.In the present study,the interaction between ICP and the cerebral venous system and its possible mechanism were investigated with respect to the biological characteristics of the cerebral venous system and its hemodynamic response under increased ICP.@@Methods We created intracranial hypertension animal model,measured and calculated the venous flow velocity and diameter of the outflow terminal of the CVS with color ultrasonic system and recorded the vascular morphology by 3-dimensional anatomical microscopy.Patients who suffered from raised ICP underwent MRI and digital subtraction angiography (DSA) examination to show the length in the vertical direction of the wall of the bridging vein representing the diameter value.Pathological autopsy was performed from bodies of patients who had died from non-cerebral causes to observe the juncture part between the venous sinuses and tributary vertical brain veins.@@Results Under increased ICP conditions,venous drainage through the outlet cuff segment,a unique structure between the bridge vein and sinus,was obstructed and in turn venous blood became congested.Therefore,the increased blood volume worsened the pre-existing ICP according to the well-accepted theory regarding volume-pressure relationship.This phenomenon was described as concurrent “Venogenic intracranial hypertension”,which is characterized by intracranial venous blood stasis responsive to and together with the original increased ICP.@@Conclusions The existence of this special pathophysiological process is prevalent,rather than rare,in various intracranial disorders.This finding would definitely provide new insight into the area of cerebral venous system research.

  15. Effects of deafness and cochlear implant use on temporal response characteristics in cat primary auditory cortex.

    Fallon, James B; Shepherd, Robert K; Nayagam, David A X; Wise, Andrew K; Heffer, Leon F; Landry, Thomas G; Irvine, Dexter R F


    We have previously shown that neonatal deafness of 7-13 months duration leads to loss of cochleotopy in the primary auditory cortex (AI) that can be reversed by cochlear implant use. Here we describe the effects of a similar duration of deafness and cochlear implant use on temporal processing. Specifically, we compared the temporal resolution of neurons in AI of young adult normal-hearing cats that were acutely deafened and implanted immediately prior to recording with that in three groups of neonatally deafened cats. One group of neonatally deafened cats received no chronic stimulation. The other two groups received up to 8 months of either low- or high-rate (50 or 500 pulses per second per electrode, respectively) stimulation from a clinical cochlear implant, initiated at 10 weeks of age. Deafness of 7-13 months duration had no effect on the duration of post-onset response suppression, latency, latency jitter, or the stimulus repetition rate at which units responded maximally (best repetition rate), but resulted in a statistically significant reduction in the ability of units to respond to every stimulus in a train (maximum following rate). None of the temporal response characteristics of the low-rate group differed from those in acutely deafened controls. In contrast, high-rate stimulation had diverse effects: it resulted in decreased suppression duration, longer latency and greater jitter relative to all other groups, and an increase in best repetition rate and cut-off rate relative to acutely deafened controls. The minimal effects of moderate-duration deafness on temporal processing in the present study are in contrast to its previously-reported pronounced effects on cochleotopy. Much longer periods of deafness have been reported to result in significant changes in temporal processing, in accord with the fact that duration of deafness is a major factor influencing outcome in human cochlear implantees.

  16. Experimental damage detection of cracked beams by using nonlinear characteristics of forced response

    Andreaus, U.; Baragatti, P.


    Experimental evaluation of the flexural forced vibrations of a steel cantilever beam having a transverse surface crack extending uniformly along the width of the beam was performed, where an actual fatigue crack was introduced instead - as usual - of a narrow slot. The nonlinear aspects of the dynamic response of the beam under harmonic excitation were considered and the relevant quantitative parameters were evaluated, in order to relate the nonlinear resonances to the presence and size of the crack. To this end, the existence of sub- and super-harmonic components in the Fourier spectra of the acceleration signals was evidenced, and their amplitudes were quantified. In particular, the acceleration signals were measured in different positions along the beam axis and under different forcing levels at the beam tip. The remarkable relevance of the above mentioned nonlinear characteristics, and their substantial independence on force magnitude and measurement point were worthily noted in comparison with the behavior of the intact beam. Thus, a reliable method of damage detection was proposed which was based on simple tests requiring only harmonically forcing and acceleration measuring in any point non-necessarily near the crack. Then, the time-history of the acceleration recorded at the beam tip was numerically processed in order to obtain the time-histories of velocity and displacement. The nonlinear features of the forced response were described and given a physical interpretation in order to define parameters suitable for damage detection. The efficiency of such parameters was discussed with respect to the their capability of detecting damage and a procedure for damage detection was proposed which was able to detect even small cracks by using simple instruments. A finite element model of the cantilever beam was finally assembled and tuned in order to numerically simulate the results of the experimental tests.

  17. A Precision and High-Speed Behavioral Simulation Method for Transient Response and Frequency Characteristics of Switching Converters

    Sai, Toru; Sugimoto, Shoko; Sugimoto, Yasuhiro

    We propose a fast and precise transient response and frequency characteristics simulation method for switching converters. This method uses a behavioral simulation tool without using a SPICE-like analog simulator. The nonlinear operation of the circuit is considered, and the nonlinear function is realized by defining the nonlinear formula based on the circuit operation and by applying feedback. To assess the accuracy and simulation time of the proposed simulation method, we designed current-mode buck and boost converters and fabricated them using a 0.18-µm high-voltage CMOS process. The comparison in the transient response and frequency characteristics among SPICE, the proposed program on a behavioral simulation tool which we named NSTVR (New Simulation Tool for Voltage Regulators) and experiments of fabricated IC chips showed good agreement, while NSTVR was more than 22 times faster in transient response and 85 times faster in frequency characteristics than SPICE in CPU time in a boost converter simulation.

  18. Interpreting broad emission-line variations II: Tensions between luminosity, characteristic size and responsivity

    Goad, Michael R


    We investigate the variability behaviour of the broad Hb emission-line to driving continuum variations in the best-studied AGN NGC 5548. For a particular choice of BLR geometry, Hb surface emissivity based on photoionization models, and using a scaled version of the 13 yr optical continuum light curve as a proxy for the driving ionizing continuum, we explore several key factors that determine the broad emission line luminosity L, characteristic size R(RW), and variability amplitude (i.e., responsivity) eta, as well as the interplay between them. For fixed boundary models which extend as far as the hot-dust the predicted delays for Hb are on average too long. However, the predicted variability amplitude of Hb provides a remarkably good match to observations except during low continuum states. We suggest that the continuum flux variations which drive the redistribution in Hb surface emissivity F(r) do not on their own lead to large enough changes in R(RW) or eta(eff). We thus investigate dust-bounded BLRs for w...

  19. Dynamic response characteristics of the high-temperature superconducting maglev system under lateral eccentric distance

    Wang, Bo; Zheng, Jun; Si, Shuaishuai; Qian, Nan; Li, Haitao; Li, Jipeng; Deng, Zigang


    Off-centre operation of high-temperature superconducting (HTS) maglev systems caused by inevitable conditions such as the misregistration of vehicle, crosswind and curve negotiation, may change the distribution of the trapped flux in the HTS bulks and the magnetic interaction between HTS bulks and the PMG. It impacts on the performance of HTS maglev, and more seriously makes the maglev vehicle overturned. Therefore, understanding the performance of the HTS maglev in off-center operation is very important. In this paper, the dynamic response characteristics of a cryostat with twenty-four onboard YBaCuO superconductor bulks were experimentally investigated at different eccentric distances under loads before the initial FC process. Parameters such as vibration accelerations, displacement, natural frequency and dynamic stiffness were acquired and analyzed via the B&K vibration analyzer and laser displacement sensors. Results suggest that the natural frequency and dynamic stiffness of the maglev vehicle would be obviously reduced with the eccentric distance, posing negative effects on the stability of HTS maglev.

  20. Negative differential resistance and characteristic nonlinear electromagnetic response of a Topological Insulator

    Lee, Ching Hua; Zhang, Xiao; Guan, Bochen


    Materials exhibiting negative differential resistance have important applications in technologies involving microwave generation, which range from motion sensing to radio astronomy. Despite their usefulness, there has been few physical mechanisms giving rise to materials with such properties, i.e. GaAs employed in the Gunn diode. In this work, we show that negative differential resistance also generically arise in Dirac ring systems, an example of which has been experimentally observed in the surface states of Topological Insulators. This novel realization of negative differential resistance is based on a completely different physical mechanism from that of the Gunn effect, relying on the characteristic non-monotonicity of the response curve that remains robust in the presence of nonzero temperature, chemical potential, mass gap and impurity scattering. As such, it opens up new possibilities for engineering applications, such as frequency upconversion devices which are highly sought for terahertz signal generation. Our results may be tested with thin films of Bi2Se3 Topological Insulators, and are expected to hold qualitatively even in the absence of a strictly linear Dirac dispersion, as will be the case in more generic samples of Bi2Se3 and other materials with topologically nontrivial Fermi sea regions.

  1. Defense Response Characteristics of Suburban Pine Stands of Krasnoyarsk City at Early Stage of Anthropogenous Damage

    G. G. Polyakova


    Full Text Available In 2002–2013, on permanent sample plots (PPs, the condition of suburban middle-aged pine stands of Krasnoyarsk was investigated. Annual assessments of parameters of defense response of stem phloem of the sample trees on the action of extractives from mycelium Ceratocystis laricicola (Redfern & Minter were carried out. The size of a phloem necrosis and its shift along a stem relative to inoculation hole were measured. The pine stands (polluted and conditionally background are convenient for determining condition changes at early stages of damage. These stands are affected by different anthropogenic factors, but don't differ in vigor state as visually estimated on a 6-point scale of Forest Regulation of Russian Federation. PPs have similar forest inventory characteristics, except for PPs on an edge of polluted pine forest where the site class is reduced. Significant shift of necrosis in phloem up on a stem within two years following a year when there was a spring creeping fire is registered. It proves the reversal of normal basipetal transport of assimilates toward crown and feasibility of using necrosis asymmetry for assessment of fire influence on physiological condition of pine stands. The increase of necroses size (decrease of resistance after a fire was noted during later period in comparison with reversal of transport of assimilates in the stem. Influence of a chemical burn of needles on acropetal shift of necrosis was expressed to a lesser extent in comparison with a fire.


    Zoe K. Pafili


    Full Text Available The effect of resistance exercise on blood lipids is not clear yet. The purpose of this study was to examine the cholesterol responses to a heavy resistance leg press exercise emphasizing on the eccentric movement 24 and 48 hours following exercise and to quantify the cardiorespiratory responses of the exercise bout in an attempt to clarify the exercise characteristics that may be responsible for the effects of heavy resistance exercise on blood lipids. Nine healthy, untrained male volunteers aged 27.2 ± 1.1 yrs (76.2 ± 2.5 kg, 1.79 ± 0.02 m performed a session of heavy RE emphasizing on the eccentric movement consisting of eight sets of inclined leg presses at six repetition maximum with 3-min rest intervals. Venous blood samples were obtained at rest (control and 24 and 48 hours following exercise. Average VO2 at rest was 4.0 ± 0.4 ml·min-1·kg-1, during exercise 19.6 ± 0.2 ml·min-1·kg-1 and during the 180 sec recovery period between sets 12.5 ± 0.2 ml·min-1·kg-1. RER values decreased with the progression of the exercise and were significantly lower during the last four sets compared with the first four sets of the exercise session. Resting heart rate was 67 ± 2 bpm, and maximum heart rate during exercise was 168 ± 1 bpm. Serum creatine kinase was significantly elevated on day 1 (1090 ± 272 U·L-1, p < 0.03 and peaked on day 2 (1230 ± 440 U·L-1 p < 0. 01. Total cholesterol, HDL cholesterol and calculated LDL cholesterol concentration did not change significantly following with exercise. This protocol of heavy resistance exercise has no effect on TC or cholesterol sub-fraction concentration 24 and 48 hours following exercise which may be due to the low energy expenditure of the exercise and/or to the gender of the participants


    Hata, Yoshiya; Ichii, Koji; Yamada, Masayuki; Tokida, Ken-Ichi; Takezawa, Koichiro; Shibao, Susumu; Mitsushita, Junji; Murata, Akira; Furukawa, Aiko; Koizumi, Keigo

    Accurate evaluation on the seismic response characteristics of a road embankment is very important for the rational seismic assessment. However, in a lot of previous studies, the seismic response characteristics of an embankment were evaluated based on the results of shaking table test, centrifuge model test and dynamic FEM analysis. In this study, the transfer function and the shear wave velocity of a road embankment were evaluated based on the in-situ records of moderate earthquake observation and microtremor measurement. Test results show the possibility that the shear wave velocity of an embankment can be estimated by the earthquake observation or the microtremor measurement and the dynamic linear FEM analysis.

  4. Development of a Multi-Scale Methodology for Prediction of the Microscopic Anisotropic Stress-Strain Response of Textured Metals under Dynamic Loading


    continued attention, which is related to platform calculations for crash-worthiness and foreign-object damage in aerospace systems, ballistic and...Havner, K.S. (1982) Perspectives in the mechanics of elastoplastic crystals. J. Mech. Phys. Solids , 30, 5–22. [61] Hill, R. (1966) Generalised

  5. Structural characteristics correlate with immune responses induced by HIV envelope glycoprotein vaccines.

    Sharma, Victoria A; Kan, Elaine; Sun, Yide; Lian, Ying; Cisto, Jimna; Frasca, Verna; Hilt, Susan; Stamatatos, Leonidas; Donnelly, John J; Ulmer, Jeffrey B; Barnett, Susan W; Srivastava, Indresh K


    quality of the immune responses induced in rabbits. These data suggest that biophysical characteristics of HIV Env, such as affinity for CD4, and exposure of important neutralizing epitopes, such as those recognized by b12 mAb, may be important predictors of its in vivo efficacy and may serve as important surrogate markers for screening Env structures as potential vaccine candidates.

  6. Characterization and Stress-Strain Relationship of Leached Concrete%溶蚀混凝土的表征及应力-应变关系

    黄蓓; 钱春香


    溶蚀作用导致水泥基材料的孔隙率增加从而影响材料的传输及力学性能.对于结构中的既有混凝土,采用非破损和局部破损方法测量和评估溶蚀混凝士的承载力是非常重要的.采用酚酞指示剂法、孔隙溶液pH测量法、超声波无损检测法,对溶蚀混凝土进行了溶蚀损伤程度表征;试验测试了溶蚀混凝七的单轴应力一应变关系:采用XRD和压汞分析研究了混凝土溶蚀机理.研究表明:酚酞指示剂法可以较为直观的表征溶蚀损伤深度,测量的溶蚀程度与强度衰减较为接近:Ca(OH)2和C-S-H凝胶在溶蚀过程中同时溶出,Ca(OH)2是造成早期溶蚀质量损伤的主要原因:混凝土溶蚀后有害孔的数量增加,对混凝土的耐久性产生不利影响;溶蚀混凝土的应力-应变关系曲线形状与普通混凝土相似,但表现出良好的延性及韧性.%Leaching of cementitious materials leads to an increase in porosity, which has important consequences on transport and mechanical properties. It is thus important to investigate the methods that can be used in unleached concrete to evaluate the residual bearing capacity of leached concrete. In this paper, the degradation degree of leached concrete was characterized by three methods (i.e., spraying phenolphthalein, pH value of pore solution, velocity of supersonic). The stress-strain curve of leached concrete under unaxial loads was examined by a material test system. The kinetics of degradation was analyzed by X-ray diffraction and mercury intrusion test. The results show that spraying phenolphthalein is an effective way to characterize the leaching degradation related to attenuation of compressive strength. The dissolution happened both in portlandite and C-S-H gel during the leaching duration and the dissolution of portlandite is a main cause of mass loss at the early stages of leaching. A number of harmful pores with the size above 200 nm increased in the leaching of

  7. The relationship between visual orienting responses and clinical characteristics in children attending special education for the visually impaired.

    Kooiker, Marlou J G; Pel, Johan J M; van der Steen, Johannes


    We recently introduced a method based on quantification of orienting responses toward visual stimuli to assess the quality of visual information processing in children. In the present study, we examined the relationship between orienting responses and factors that are associated with visual processing impairments in current clinical practice. Response time and fixation quality to visual features such as form, contrast, motion, and color stimuli were assessed in 104 children from 1 to 12 years attending special education for the visually impaired. Using regression analysis, we investigated whether these parameters were affected by clinical characteristics of children. Response times significantly depended on stimulus type. Responses to high-contrast cartoons were significantly slower in children with a clinical diagnosis of cerebral visual impairment. Fixation quality was significantly affected by visual acuity and nystagmus. The results suggest that the quantitative measurement of orienting responses is strongly related to cerebral visual impairment in children.

  8. Reproductive responses and productive characteristics in ewes supplemented with detoxified castor meal for a long period

    Liliane Moreira Silva


    Full Text Available The objective of the present study was to evaluate the effects of supplementation with detoxified castor meal (DCM in the diet of ewes during pregnancy, partum, and post-partum on the weight development of their offspring and at slaughter. The study included 56 ewes with synchronized estrus that were naturally mated. At the beginning of pregnancy and in post-partum, hepatic and renal function-related parameters and progesterone levels were measured. At slaughter, the proximate composition and fatty acid profile were determined in the loin of ewes. There was no effect of diet on reproductive response after estrus synchronization. At the beginning of pregnancy, albumin and creatinine levels were lower in the DCM group. Supplementation with DCM did not alter the weight or body condition of ewes at partum. However, at weaning, the DCM group showed a higher loin-eye area (LEA in relation to the group fed diets without detoxified castor meal (WDCM. At partum, as well as at weaning, the offspring of the ewes supplemented with DCM had a larger LEA than the WDCM group. In post-partum, levels of glucose, urea, protein, and cholesterol were lower in the DCM group. The return to cyclicity was similar in both groups, with an average of 47 days after partum. At slaughter, neither anatomical and carcass components nor the results of the proximate analysis were affected by the type of diet, except for an increase in heptadecanoic acid in the DCM group. Supplementation with detoxified castor meal in the diet of ewes does not affect lambing, pregnancy, prolificacy, return to cyclicity, milk production, blood biochemical parameters, or carcass characteristics.

  9. Nonlinear structural joint model updating based on instantaneous characteristics of dynamic responses

    Wang, Zuo-Cai; Xin, Yu; Ren, Wei-Xin


    This paper proposes a new nonlinear joint model updating method for shear type structures based on the instantaneous characteristics of the decomposed structural dynamic responses. To obtain an accurate representation of a nonlinear system's dynamics, the nonlinear joint model is described as the nonlinear spring element with bilinear stiffness. The instantaneous frequencies and amplitudes of the decomposed mono-component are first extracted by the analytical mode decomposition (AMD) method. Then, an objective function based on the residuals of the instantaneous frequencies and amplitudes between the experimental structure and the nonlinear model is created for the nonlinear joint model updating. The optimal values of the nonlinear joint model parameters are obtained by minimizing the objective function using the simulated annealing global optimization method. To validate the effectiveness of the proposed method, a single-story shear type structure subjected to earthquake and harmonic excitations is simulated as a numerical example. Then, a beam structure with multiple local nonlinear elements subjected to earthquake excitation is also simulated. The nonlinear beam structure is updated based on the global and local model using the proposed method. The results show that the proposed local nonlinear model updating method is more effective for structures with multiple local nonlinear elements. Finally, the proposed method is verified by the shake table test of a real high voltage switch structure. The accuracy of the proposed method is quantified both in numerical and experimental applications using the defined error indices. Both the numerical and experimental results have shown that the proposed method can effectively update the nonlinear joint model.

  10. Differential clinical characteristics, medication usage, and treatment response of bipolar disorder in the US versus The Netherlands and Germany

    Post, Robert M.; Leverich, Gabriele S.; Altshuler, Lori L.; Frye, Mark A.; Suppes, Trisha; Keck, Paul E.; McElroy, Susan L.; Nolen, Willem A.; Kupka, Ralph; Grunze, Heinz; Walden, Joerg; Rowe, Mike


    Increased early-onset bipolar illness was seen in the US compared with the Netherlands and Germany (abbreviated here as Europe), but other clinical characteristics, medication use, and treatment response have not been systematically explored. Outpatients with bipolar disorder were treated naturalist

  11. Diuretic response in patients with acute decompensated heart failure : characteristics and clinical outcome-an analysis from RELAX-AHF

    Voors, Adriaan A.; Davison, Beth A.; Teerlink, John R.; Felker, G. Michael; Cotter, Gad; Filippatos, Gerasimos; Greenberg, Barry H.; Pang, Peter S.; Levin, Bruce; Hua, Tsushung A.; Severin, Thomas; Ponikowski, Piotr; Metra, Marco


    AimsWe studied the characteristics and clinical outcome related to diuretic response and the effects of serelaxin in patients hospitalized for acute heart failure (AHF). Methods and resultsRELAX-AHF was a double-blind, placebo-controlled trial, enrolling 1161 patients admitted to hospital for AHF wh

  12. Alexithymic characteristics in responses to the Synthetic House-Tree-Person (HTP) Drawing Test.

    Fukunishi, I; Mikami, N; Kikuchi, M


    This study examined the association of certain complex personality traits assessed by the Synthetic House-Tree-Person Drawing Test and alexithymic characteristics assessed by the 20-item Toronto Alexithymia Scale for a sample of 589 Japanese college students. Alexithymic students who scored over 61 points on the Toronto Alexithymia Scale-20 exhibited two characteristics relative to the test: poor relationships between figures and additional written explanations. These two characteristics projected on the Synthetic House-Tree-Person Drawing Test may be related to alexithymic characteristics and related factors.

  13. Quantification of Internal Stress-Strain Fields in Human Tendon: Unraveling the Mechanisms that Underlie Regional Tendon Adaptations and Mal-Adaptations to Mechanical Loading and the Effectiveness of Therapeutic Eccentric Exercise

    Maganaris, Constantinos N.; Chatzistergos, Panagiotis; Reeves, Neil D.; Narici, Marco V.


    of the stress created by the exercise and is not only reliant upon the type of muscle contraction performed. To better understand the micromechanical behavior and regional adaptability/mal-adaptability of tendon tissue it is important to estimate its internal stress-strain fields. Recent relevant advancements in numerical techniques related to tendon loading are discussed. PMID:28293194

  14. Differential clinical characteristics, medication usage, and treatment response of bipolar disorder in the US versus The Netherlands and Germany.

    Post, Robert M; Leverich, Gabriele S; Altshuler, Lori L; Frye, Mark A; Suppes, Trisha; Keck, Paul E; McElroy, Susan L; Nolen, Willem A; Kupka, Ralph; Grunze, Heinz; Walden, Joerg; Rowe, Mike


    Increased early-onset bipolar illness was seen in the US compared with the Netherlands and Germany (abbreviated here as Europe), but other clinical characteristics, medication use, and treatment response have not been systematically explored. Outpatients with bipolar disorder were treated naturalistically and followed prospectively at four sites in the US and three in Europe. Data and clinical characteristics were collected from patient questionnaires, and medication usage and good-to-excellent response to treatment for at least 6 months ascertained from daily clinician ratings on the National Institutes of Mental Health-Life Chart Method. Almost all clinical characteristics earlier associated with a poor treatment response were more prevalent in the US than in Europe, including early onset, environmental adversity, rapid cycling, more than 20 prior episodes, comorbid anxiety and substance abuse disorders, and a positive parental history for an affective disorder. Lithium was used more frequently in Europe than in the US and had a higher rate of success, whereas valproate was used more in the US, with a trend toward higher success in Europe. Antidepressants were used more in the US, but had extremely low success rates. Many other agents were deployed differently on the two continents, but success rates were consistently lower in the US than in Europe. In conclusion, clinical characteristics and patterns of medication usage and effectiveness differed markedly in the two continents suggesting the need for uncovering explanations and considering the two populations as heterogeneous in the future pharmacological studies.

  15. Rheological Properties with Temperature Response Characteristics and a Mechanism of Solid-Free Polymer Drilling Fluid at Low Temperatures

    Sheng Wang


    Full Text Available The rheological properties of drilling fluid have important effects during drilling in natural gas hydrate at low temperatures. The present study was performed using theoretical analysis. Experiments and micro-analyses were carried out to determine the rheological properties with temperature response characteristics and the mechanism involved in solid-free polymer drilling fluid (SFPDF at low temperatures when drilling in permafrost with natural gas hydrates (NGH. The curves of shear stress with the shear rates of three kinds of polymer drilling fluids, Semen Lepidii natural vegetable gum, polyacrylamide, and xanthan gum, were drawn. Then, statistical and related analyses of test data were performed using Matlab ver. 8.0. Through regression analysis, the Herschel–Bulkley model was used to characterize the rheological characteristics of SFPDF. On this basis, the laws regarding the rheological properties of the three kinds of SFPDF under changing temperatures were analyzed and rheological properties with temperature response state equations were established. Next, the findings of previous studies on rheological properties with temperature response characteristics of the SFPDF were reviewed. Finally, the rheological properties with temperature response mechanisms were assessed using scanning electron microscopy and infrared spectrum analysis.

  16. Epidemiological and Clinical Baseline Characteristics as Predictive Biomarkers of Response to Anti-VEGF Treatment in Patients with Neovascular AMD

    Miltiadis K. Tsilimbaris


    Full Text Available Purpose. To review the current literature investigating patient response to antivascular endothelial growth factor-A (VEGF therapy in the treatment of neovascular age-related macular degeneration (nAMD and to identify baseline characteristics that might predict response. Method. A literature search of the PubMed database was performed, using the keywords: AMD, anti-VEGF, biomarker, optical coherence tomography, treatment outcome, and predictor. The search was limited to articles published from 2006 to date. Exclusion criteria included phase 1 trials, case reports, studies focusing on indications other than nAMD, and oncology. Results. A total of 1467 articles were identified, of which 845 were excluded. Of the 622 remaining references, 47 met all the search criteria and were included in this review. Conclusion. Several baseline characteristics correlated with anti-VEGF treatment response, including best-corrected visual acuity, age, lesion size, and retinal thickness. The majority of factors were associated with disease duration, suggesting that longer disease duration before treatment results in worse treatment outcomes. This highlights the need for early treatment for patients with nAMD to gain optimal treatment outcomes. Many of the identified baseline characteristics are interconnected and cannot be evaluated in isolation; therefore multivariate analyses will be required to determine any specific relationship with treatment response.

  17. Effect of Rake Angle on Stress, Strain and Temperature on the Edge of Carbide Cutting Tool in Orthogonal Cutting Using FEM Simulation

    Hendri Yanda


    Full Text Available Demand for higher productivity and good quality for machining parts has encourage many researchers to study the effects of machining parameters using FEM simulation using either two or three dimensions version. These are due to advantages such as software package and computational times are required. Experimental work is very costly, time consuming and labor intensive. The present work aims to simulate a three-dimensional orthogonal cutting operations using FEM software (Deform-3D to study the effects of rake angle on the cutting force, effective stress, strain and temperature on the edge of carbide cutting tool. There were seven runs of simulations. All simulations were performed for various rake angles of -15 deg, -10 deg, -5 deg, 0 deg, +5 deg, +10 deg, and +15 deg. The cutting speed, feed rate and depth of cut (DOC were kept constant at 100 m/min, 0.35 mm/rev and 0.3 mm respectively. The work piece used was ductile cast iron FCD500 grade and the cutting tool was DNMA432 series (tungsten, uncoated carbide tool, SCEA = 0; and radius angle 55 deg. The analysis of results show that, the increase in the rake angle from negative to positive angle, causing the decrease in cutting force, effective stress and total Von Misses strain. The minimum of the cutting force, effective stress and total Von Misses strain were obtained at rake angle of +15 deg. Increasing the rake caused higher temperature generated on the edge of carbide cutting tool and resulted in bigger contact area between the clearance face and the workpiece, consequently caused more friction and wear. The biggest deformation was occurred in the primary deformation zone, followed by the secondary deformation zone. The highest stress was also occurred in the primary deformation zone. But the highest temperature on the chip usually occurs in secondary deformation zone, especially in the sliding region, because the heat that was generated in the sticking region increased as the workpiece was

  18. Identifying factors related to Achilles tendon stress, strain, and stiffness before and after 6 months of growth in youth 10-14 years of age.

    Neugebauer, Jennifer M; Hawkins, David A


    The purposes of this study were (1) determine if youth peak Achilles tendon (AT) strain, peak AT stress, and AT stiffness, measured during an isometric plantar flexion, differed after six months (mos) of growth, and (2) determine if sex, physical activity level (Physical Activity Questionnaire (PAQ-C)), and/or growth rate (GR) were related to these properties. AT stress, strain, and stiffness were quantified in 20 boys (13.47±0.81 years) and 22 girls (11.18±0.82 years) at 2 times (0 and 6 mos). GR (change in height in 6 mos) was not significantly different between boys and girls (3.5±1.4 and 3.4±1.1cm/6 mos respectively). Peak AT strain and stiffness (mean 3.8±0.4% and 128.9±153.6N/mm, respectively) did not differ between testing sessions or sex. Peak AT stress (22.1±2.4 and 24.0±2.1MPa at 0 and 6 mos, respectively) did not differ between sex and increased significantly at 6 mos due to a significant decrease in AT cross-sectional area (40.6±1.3 and 38.1±1.6mm(2) at 0 and 6 mos, respectively) with no significant difference in peak AT force (882.3±93.9 and 900.3± 65.5N at 0 and 6 mos, respectively). Peak AT stress was significantly greater in subjects with greater PAQ-C scores (9.1% increase with 1 unit increase in PAQ-C score) and smaller in subjects with faster GRs (13.8% decrease with 1cm/6 mos increase in GR). These results indicate that of the AT mechanical properties quantified, none differed between sex, and only peak AT stress significantly differed after 6 months and was related to GR and physical activity.

  19. Dynamic response characteristics of thermoelectric generator predicted by a three-dimensional heat-electricity coupled model

    Meng, Jing-Hui; Zhang, Xin-Xin; Wang, Xiao-Dong


    The practical application environments of thermoelectric generators (TEGs) always change, which make a requirement for studying the dynamic response characteristics of TEGs. This work develops a complete, three-dimensional and transient model to investigate this issue. The model couples the energy and electric potential equations. Seebeck effect, Peltier effect, Thomson effect, Joule heating and Fourier heat conduction are taken into account in this model. Dynamic output power and conversion efficiency of the TEG, which are caused by variations of the hot end temperature, cold end temperature and load current, are studied. The response hysteresis of the output power to the hot end and cold end temperatures, the overshoot or undershoot of the conversion efficiency are found and attributed to the delay of thermal diffusion. However, the output power is synchronous with the load current due to much faster electric response than thermal response.

  20. Engineering characterization of ground motion. Task I. Effects of characteristics of free-field motion on structural response

    Kennedy, R.P.; Short, S.A.; Merz, K.L.; Tokarz, F.J.; Idriss, I.M.; Power, M.S.; Sadigh, K.


    This report presents the results of the first task of a two-task study on the engineering characterization of earthquake ground motion for nuclear power plant design. The overall objective of this study is to develop recommendations for methods for selecting design response spectra or acceleration time histories to be used to characterize motion at the foundation level of nuclear power plants. Task I of the study develops a basis for selecting design response spectra, taking into account the characteristics of free-field ground motion found to be significant in causing structural damage.

  1. Characteristics and dynamic response of 3-D component base isolation system using ball bearings and air springs

    Tsutsumi, Hideaki; Yamada, Hiroyuki; Mori, Kazunari; Ebisawa, Katsumi; Shibata, Katsuyuki [Seismic Emergency Information System Research Team, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)


    Introduction of the base isolation technique into the seismic design of nuclear power plant components as well as buildings has been expected as one of effective countermeasure to reduce the seismic force applied to components. A research program on the base isolation of nuclear components has been carried out at the Japan Atomic Energy Research Institute (JAERI) since 1991. A methodology and a computer code (EBISA: Equipment Base Isolation System Analysis) for evaluating the failure frequency of the nuclear component with the base isolation were developed. In addition, a test program, which is concerned with the above development, aiming at improvement of failure frequency analysis models in the code has been conducted since 1996 to investigate the dynamic behavior and to verify the effectiveness of component base isolation systems. Two base isolation test systems with different characteristics were fabricated and static and dynamic characteristics were measured by static loading and free vibration tests. One which consists of ball bearings and air springs was installed on the test bed to observe the dynamic response under natural earthquake motion. The effect of base isolation system has been observed under several earthquakes. Three-dimensional response and effect of base isolation of another system using multi-layer-rubber-bearings and coil springs has been investigated against various large earthquake motions by shaking table test. This report describes the design specification of the base isolation system using ball bearings and air springs, dynamic characteristics, dynamic response against natural seismic motion and results of dynamic response analysis considering the various characteristics of isolation devices. (author)

  2. Teachers' Responses to Bullying Incidents: Effects of Teacher Characteristics and Contexts

    Yoon, Jina; Sulkowski, Michael L.; Bauman, Sheri A.


    School is a critical context of bullying. This study investigated teacher responses to bullying incidents and the effects of individual and contextual variables on these responses. Participating teachers (N = 236) viewed streaming video vignettes depicting physical, verbal, and relational bullying and reported how they would respond to bullies and…

  3. Teachers' Responses to Bullying Incidents: Effects of Teacher Characteristics and Contexts

    Yoon, Jina; Sulkowski, Michael L.; Bauman, Sheri A.


    School is a critical context of bullying. This study investigated teacher responses to bullying incidents and the effects of individual and contextual variables on these responses. Participating teachers (N = 236) viewed streaming video vignettes depicting physical, verbal, and relational bullying and reported how they would respond to bullies and…

  4. Hydrological response times in lowland urban catchments characteristed by looped drainage systems

    Ten Veldhuis, J.A.E.; Skovgard Olsen, A.


    Hydrological response times are often used to characterise runoff processes. They provide information about temporal resolution of catchments responses, thus of the required measurement resolutions of in-situ sensors as well as spatial sensors like rainfall radars. The objective of this study was to

  5. Estimating the ride quality characteristics of vehicles with random decrement analysis of on-the-road vibration response data

    Ainalis, Daniel; Rouillard, Vincent; Sek, Michael


    This paper describes the application of a practical analytical technique based on the random decrement method to estimate the rigid sprung mass dynamic characteristics (frequency response function) of road vehicles using only vibration response data during constant-speed operation. A brief history and development of the random decrement technique is presented, along with a summary of work undertaken on optimal parameter selection to establish the random decrement signature. Two approaches to estimate the dynamic characteristics from the random decrement signature are described and evaluated. A custom, single-wheeled vehicle (physical quarter car) was commissioned to undertake a series of on-the-road experiments at various nominally constant operating speeds. The vehicle, also instrumented as an inertial profilometer, simultaneously measured the longitudinal pavement profile to establish the vehicle's actual dynamic characteristics during operation. The main outcome of the paper is that the random decrement technique can be used to provide accurate estimates of the sprung mass mode of the vehicle's dynamic characteristics for both linear and nonlinear suspension systems of an idealised vehicle.

  6. Gender differences in rival characteristics that evoke jealousy in response to emotional versus sexual infidelity

    Buunk, Abraham (Bram); Dijkstra, Pieternel


    Previous research has shown that in men jealousy is evoked more by a rival's status-related characteristics than in women, whereas in women jealousy is evoked more by a rival's physical attractiveness than in men. The present study examined whether the occurrence of this gender difference depends

  7. Analysis of genotype differences of rice response to low Zn activity and some morphological characteristics



    Zinc deficiency is one of the most widespread micro-nutritional disorder for rice. To solve the problem, screening Zn-efficient cuivivars is an available method and understanding genotype difference of Zn efficiency and their morphological and physiological characteristics is important.

  8. Content Validity and Psychometric Characteristics of the "Knowledge about Older Patients Quiz" for Nurses Using Item Response Theory.

    Dikken, Jeroen; Hoogerduijn, Jita G; Kruitwagen, Cas; Schuurmans, Marieke J


    To assess the content validity and psychometric characteristics of the Knowledge about Older Patients Quiz (KOP-Q), which measures nurses' knowledge regarding older hospitalized adults and their certainty regarding this knowledge. Cross-sectional. Content validity: general hospitals. Psychometric characteristics: nursing school and general hospitals in the Netherlands. Content validity: 12 nurse specialists in geriatrics. Psychometric characteristics: 107 first-year and 78 final-year bachelor of nursing students, 148 registered nurses, and 20 nurse specialists in geriatrics. Content validity: The nurse specialists rated each item of the initial KOP-Q (52 items) on relevance. Ratings were used to calculate Item-Content Validity Index and average Scale-Content Validity Index (S-CVI/ave) scores. Items with insufficient content validity were removed. Psychometric characteristics: Ratings of students, nurses, and nurse specialists were used to test for different item functioning (DIF) and unidimensionality before item characteristics (discrimination and difficulty) were examined using Item Response Theory. Finally, norm references were calculated and nomological validity was assessed. Content validity: Forty-three items remained after assessing content validity (S-CVI/ave = 0.90). Psychometric characteristics: Of the 43 items, two demonstrating ceiling effects and 11 distorting ability estimates (DIF) were subsequently excluded. Item characteristics were assessed for the remaining 30 items, all of which demonstrated good discrimination and difficulty parameters. Knowledge was positively correlated with certainty about this knowledge. The final 30-item KOP-Q is a valid, psychometrically sound, comprehensive instrument that can be used to assess the knowledge of nursing students, hospital nurses, and nurse specialists in geriatrics regarding older hospitalized adults. It can identify knowledge and certainty deficits for research purposes or serve as a tool in educational

  9. Bone Response to Surface-Modified Titanium Implants: Studies on the Early Tissue Response to Implants with Different Surface Characteristics

    C. Larsson Wexell


    Full Text Available In a series of experimental studies, the bone formation around systematically modified titanium implants is analyzed. In the present study, three different surface modifications were prepared and evaluated. Glow-discharge cleaning and oxidizing resulted in a highly stoichiometric TiO2 surface, while a glow-discharge treatment in nitrogen gas resulted in implants with essentially a surface of titanium nitride, covered with a very thin titanium oxide. Finally, hydrogen peroxide treatment of implants resulted in an almost stoichiometric TiO2, rich in hydroxyl groups on the surface. Machined commercially pure titanium implants served as controls. Scanning Auger Electron Spectroscopy, Scanning Electron Microscopy, and Atomic Force Microscopy revealed no significant differences in oxide thickness or surface roughness parameters, but differences in the surface chemical composition and apparent topography were observed. After surface preparation, the implants were inserted in cortical bone of rabbits and evaluated after 1, 3, and 6 weeks. Light microscopic evaluation of the tissue response showed that all implants were in contact with bone and had a large proportion of newly formed bone within the threads after 6 weeks. There were no morphological differences between the four groups. Our study shows that a high degree of bone contact and bone formation can be achieved with titanium implants of different surface composition and topography.

  10. Meta-analysis of placebo responses in central neuropathic pain: impact of subject, study, and pain characteristics.

    Cragg, Jacquelyn J; Warner, Freda M; Finnerup, Nanna Brix; Jensen, Mark P; Mercier, Catherine; Richards, John Scott; Wrigley, Paul; Soler, Dolors; Kramer, John L K


    The placebo response is a complex construct related to psychobiological effects, as well as natural history and regression to the mean. Moreover, patient and study design characteristics have also been proposed as significantly affecting placebo responses. The aim of the current investigation was to identify factors that contribute to variable placebo responses in clinical trials involving individuals with central neuropathic pain. To this end, we performed a systematic review and meta-analysis of placebo-controlled trials examining pharmacological and noninvasive brain stimulation interventions for central neuropathic pain. Study design, subject characteristics, and pain ratings for the placebo group were extracted from each trial. Pooling of results and identification of moderating factors were carried out using random effects meta-analysis and meta-regression techniques. A total of 39 published trials met the inclusion criteria (spinal cord injury, n = 26; stroke, n = 6; multiple sclerosis, n = 7). No significant publication bias was detected. Overall, there was a significant effect for placebo to reduce central pain (-0.64, CI: -0.83 to -0.45). Smaller placebo responses were associated with crossover-design studies, longer pain duration, and greater between-subject baseline pain variability. There were no significant effects for neurological condition (stroke vs multiple sclerosis vs spinal cord injury) or the type of intervention (eg, pharmacological vs noninvasive brain stimulation). In a planned subanalysis, the severity of damage in the spinal cord also had no significant effect on the placebo response. Further study is warranted to identify factors that may explain the impact of pain duration on the placebo response at the individual subject level.

  11. The decay of Redox-stress Response Capacity is a substantive characteristic of aging: Revising the redox theory of aging.

    Meng, Jiao; Lv, Zhenyu; Qiao, Xinhua; Li, Xiaopeng; Li, Yazi; Zhang, Yuying; Chen, Chang


    Aging is tightly associated with redox events. The free radical theory of aging indicates that redox imbalance may be an important factor in the aging process. Most studies about redox and aging focused on the static status of oxidative stress levels, there has been little research investigating differential responses to redox challenge during aging. In this study, we used Caenorhabditis elegans and human fibroblasts as models to compare differential responses to oxidative stress challenge in young and old individuals. In response to paraquat stress, young individuals generated more ROS and activated signaling pathways including p-ERK, p-AKT and p-AMPKα/β. After the initial response, young individuals then promoted NRF2 translocation and induced additional antioxidant enzymes and higher expression of phase II enzymes, including SOD, CAT, GPX, HO-1, GSTP-1and others, to maintain redox homeostasis. Moreover, young individuals also demonstrated a better ability to degrade damaged proteins by up-regulating the expression of chaperones and improving proteasome activity. Based on these data, we propose a new concept "Redox-stress Response Capacity (RRC)", which suggests cells or organisms are capable of generating dynamic redox responses to activate cellular signaling and maintain cellular homeostasis. The decay of RRC is the substantive characteristic of aging, which gives a new understand of the redox theory of aging. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  12. Evaluation of seismic acceleration responses of base-isolated and nonisolated structures varying with mechanical characteristics of foundations

    You, Bong; Lee, Jae Han; Ku, Kyung Hoi [Korea Atomic Energy Research Institute, Daeduk (Korea, Republic of)


    The evaluation of acceleration responses of isolated and nonisolated structures according to mechanical features of soils is important. The kinds of soils taken in analyses are soft, medium and hard rocks, and a fixed base condition is also taken for the comparison. The horizontal isolation frequency used is 0.5 Hz. The time history analyses of reference power plant using 1940 El Centro horizontal (NS) and vertical earthquakes are performed to investigate the seismic responses varying with soil characteristics for isolated and nonisolated structures. The horizontal acceleration responses of the horizontal isolated-structures show almost similar values irrespective of the various kinds of soils and are largely decreased in the frequency ranges above 2 hz. The vertical natural frequency, 21Hz of high damping rubber bearing does not affect the vertical acceleration responses in case of soft rock, but largely affects in hard rock condition. For nonisolated structures, the acceleration responses are decreased in both horizontal and vertical directions by taking into account the soils in the analysis model. The extent of reduction of acceleration responses is larger in vertical direction than in horizontal one, as the stiffness of rock becomes softer. 8 tabs., 21 figs., 8 refs. (Author) .new.

  13. Prediction of Thermophysical and Thermomechanical Characteristics of Porous Carbon-Ceramic Composite Materials of the Heat Shield of Aerospace Craft

    Reznik, S. V.; Prosuntsov, P. V.; Mikhailovskii, K. V.


    A procedure for predicting thermophysical and thermomechanical characteristics of porous carbon-ceramic composite materials of the heat shield of aerospace craft as functions of the type of reinforcement, porosity of the structure, and the characteristics of the material's components has been developed. Results of mathematical modeling of the temperature and stressed-strained states of representative volume elements for determining the characteristics of a carbon-ceramic composite material with account taken of its anisotropy have been given.

  14. New insight into the relationships between stress, strain and mass change at Mt. Etna during the period between the 1993-94 and 2001 eruptions

    Carbone, Daniele; Aloisi, Marco; Vinciguerra, Sergio; Puglisi, Giuseppe


    During the time interval between the 1991-93 and 2001 main flank eruptions of Mt. Etna, volcanic activity was confined to the summit vents. Ground deformation and tomography studies suggest that this activity was fed by a magma body located beneath the north-west flank of the volcano, at a depth of around 7 km b.s.l.. Conversely, gravity studies indicate that the most important mass redistributions during the same period took place within an elongated volume centered below the southeastern sector of the volcano, at depths of 2-4 km b.s.l.. The phases of gravity decrease during the 1994-2001 period coincide with phases of higher strain release rate. The coupling between gravity and seismic data could reflect changes in the rate of micro-fracturing along the NNW-SSE weakness zone that cuts the SE slope of the volcano. This interpretation allows to explain why the main pressure and mass sources active at Etna during the 1994-2001 period do not coincide. The extensional dynamics of the southeastern flank of Etna may represent a second-order effect, triggered by the pressure source below the western flank and accommodated along the NNW-SSE weakness zone. In order to gain quantitative insight into the relationship between stress, strain and mass changes at Etna during the 1994-2001 period, we use a finite element modeling approach. Relying on recent studies involving stress- and temperature-induced degradation of the mechanical properties of rocks, we hypothesize that the inferred NNW-SSE weakness zone is characterized by an anomalously low Young's modulus (E). Results of our analysis are summarized in the following two points. (i) The presence of the weakness zone creates a distortion of the displacements field induced by the deeper pressure source, locally resulting in a weak extensional regime. This finding supports the hypothesis of a cause-effect relation between deeper pressurization beneath the western flank and shallower extension across the fracture zone beneath

  15. Response Characteristics of Plant Bioelectric Potential to Light Intensity Indoor and Outdoor

    Shimbo, Tatsuya; Fujii, Masaki; Sawada, Ayako; Oyabu, Takashi; Kimura, Haruhiko

    Plant is affected by environmental factors. For example, these are temperature, humidity and light intensity. The light intensity affected strongly to the plant. The plant produces glucose and oxygen with photosynthesis. Moreover, light intensity is important to purify the contaminants in the atmosphere. In this study, it was examined whether the plant is affected by temperature, wind grade and soil moisture using bioelectric potential characteristics of the plant. Especially plant bioelectric potential to light intensity change was measured. The measurement was carried out in indoor and outdoor. As for the result, the differences of plant bioelectric potential characteristics in the indoor and outdoor were recognized. At that analysis, the integrated value of plant bioelectric potential for 1 minute (vm1) was adopted. Moreover, a high correlation was indicated between the vm1 and light intensity. The correlation coefficient was R2=0.94. It becomes obvious that the plant is affected strongly by light intensity and the plant can understand the environmental factors like light intensity. The characteristics are found by measuring bioelectric potential of the plant. The environmental sensing can be possible by the use of the plant bioelectric potential.

  16. Spatiotemporal multifractal characteristics of electromagnetic radiation in response to deep coal rock bursts

    Shaobin, H.; Enyuan, W.; Xiaofei, L.


    Dynamic collapses of deeply mined coal rocks are severe threats to miners, in order to predict the collapses more accurately using electromagnetic radiation (EMR), we investigate the spatiotemporal multifractal characteristics and formation mechanism of EMR induced by underground coal mining. Coal rock in the burst-prone zone often exchanges materials and energy with its environment and gradually transits from its original stable equilibrium structure to a non-equilibrium dissipative structure with implicit spatiotemporal complexity or multifractal structures, resulting in temporal variation in multifractal EMR. The inherent law of EMR time series during damage evolution was analyzed by using time-varying multifractal theory. Results show that the time-varying multifractal characteristics of EMR are determined by damage evolutions process, the dissipated energy caused by damage evolutions such as crack propagation, fractal sliding and shearing can be regarded as the fingerprint of various EMR micro-mechanics. Dynamic spatiotemporal multifractal spectrum of EMR considers both spatial (multiple fractures) and temporal (dynamic evolution) characteristics of coal rocks, and records the dynamic evolution processes of rock bursts. Thus, it can be used to evaluate the coal deformation and fracture process. The study is of significance for us to in-depth understand EMR mechanism and to increase the accuracy of applying the EMR method to forecast dynamic disasters.

  17. Spatiotemporal multifractal characteristics of electromagnetic radiation in response to deep coal rock bursts

    Hu, S.; Wang, E.; Liu, X.


    Dynamic collapses of deeply mined coal rocks are severe threats to miners; in order to predict collapses more accurately using electromagnetic radiation (EMR), we investigate the spatiotemporal multifractal characteristics and formation mechanism of EMR induced by underground coal mining. Coal rock in the burst-prone zone often exchanges materials (gas, water and coal) and energy with its environment and gradually transitions from its original stable equilibrium structure to a nonequilibrium dissipative structure with implicit spatiotemporal complexity or multifractal structures, resulting in temporal variation in multifractal EMR. The inherent law of EMR time series during damage evolution was analyzed by using time-varying multifractal theory. Results show that the time-varying multifractal characteristics of EMR are determined by damage evolution processes. Moreover, the dissipated energy caused by the damage evolutions, such as crack propagation, fractal sliding and shearing, can be regarded as the fingerprint of various EMR micro-mechanics. The dynamic spatiotemporal multifractal spectrum of EMR considers both spatial (multiple fractures) and temporal (dynamic evolution) characteristics of coal rocks and records the dynamic evolution processes of rock bursts. Thus, it can be used to evaluate the coal deformation and fracture process. The study is of significance for us to understand the EMR mechanism in detail and to increase the accuracy of the EMR method in forecasting dynamic disasters.

  18. Spatiotemporal multifractal characteristics of electromagnetic radiation in response to deep coal rock bursts

    H. Shaobin


    Full Text Available Dynamic collapses of deeply mined coal rocks are severe threats to miners, in order to predict the collapses more accurately using electromagnetic radiation (EMR, we investigate the spatiotemporal multifractal characteristics and formation mechanism of EMR induced by underground coal mining. Coal rock in the burst-prone zone often exchanges materials and energy with its environment and gradually transits from its original stable equilibrium structure to a non-equilibrium dissipative structure with implicit spatiotemporal complexity or multifractal structures, resulting in temporal variation in multifractal EMR. The inherent law of EMR time series during damage evolution was analyzed by using time-varying multifractal theory. Results show that the time-varying multifractal characteristics of EMR are determined by damage evolutions process, the dissipated energy caused by damage evolutions such as crack propagation, fractal sliding and shearing can be regarded as the fingerprint of various EMR micro-mechanics. Dynamic spatiotemporal multifractal spectrum of EMR considers both spatial (multiple fractures and temporal (dynamic evolution characteristics of coal rocks, and records the dynamic evolution processes of rock bursts. Thus, it can be used to evaluate the coal deformation and fracture process. The study is of significance for us to in-depth understand EMR mechanism and to increase the accuracy of applying the EMR method to forecast dynamic disasters.

  19. Assessment of Patellar Tendon Reflex Responses Using Second-Order System Characteristics

    Brett D. Steineman


    Full Text Available Deep tendon reflex tests, such as the patellar tendon reflex (PTR, are widely accepted as simple examinations for detecting neurological disorders. Despite common acceptance, the grading scales remain subjective, creating an opportunity for quantitative measures to improve the reliability and efficacy of these tests. Previous studies have demonstrated the usefulness of quantified measurement variables; however, little work has been done to correlate experimental data with theoretical models using entire PTR responses. In the present study, it is hypothesized that PTR responses may be described by the exponential decay rate and damped natural frequency of a theoretical second-order system. Kinematic data was recorded from both knees of 45 subjects using a motion capture system and correlation analysis found that the mean R2 value was 0.99. Exponential decay rate and damped natural frequency ranges determined from the sample population were −5.61 to −1.42 and 11.73 rad/s to 14.96 rad/s, respectively. This study confirmed that PTR responses strongly correlate to a second-order system and that exponential decay rate and undamped natural frequency are novel measurement variables to accurately measure PTR responses. Therefore, further investigation of these measurement variables and their usefulness in grading PTR responses is warranted.

  20. Characteristics of non-response in the Danish Health Interview Surveys, 1987-1994

    Kjøller, Mette; Thoning, Henrik


    -response biased the estimated population prevalence of morbidity when solely based on responders. METHODS: The data were for the 23,096 adults sampled for the Danish Health Interview Surveys in 1987, 1991 and 1994. All were followed using the National Patient Registry to obtain such information as hospital...... data collection. CONCLUSIONS: Although admission rates differed between respondents and non-respondents these differences were too small to bias the estimated population prevalence of morbidity when solely based on respondents....... admissions. RESULTS: Non-response increased from 20.0% in 1987 to 22.6% in 1994. Four combinations of background variables characterized the non-response: gender and age; gender and civil status; county of residence and age; survey year and age. Non-respondents and respondents had identical gender- and age...


    邱宝象; 王效贵; 高增梁; Jiang Y


    提出预测缺口构件疲劳寿命的多轴局部应力应变法.采用Armstrong-Frederick (A-F)类循环塑性理论,描述具有非Masing特性的16MnR材料的循环塑性行为.结合A-F类循环塑性模型和增量式Neuber法,分析比例和非比例加载下缺口根部处的多轴应力应变状态.将局部应力应变应用于基于临界面的多轴疲劳损伤模型,对缺口构件进行疲劳损伤分析和疲劳寿命预测.分析结果表明,基于A-F类循环塑性理论的多轴局部应力应变法,能很好地描述缺口根部处的多轴应力应变状态,疲劳寿命的预测结果与试验数据基本吻合.%A multiaxial local stress-strain method was proposed to predict the fatigue life of notched components. The Armstrong-Frederick (A-F) type cyclic plasticity theory was adopted to describe the cyclic plasticity behavior. This newly developed cyclic plasticity theory is able to characterize the non-Masing behavior of 16MnR steel. The multiaxial stress-strain state at the notch root of notched components subjected to proportional and non-proportional loading was predicted by combining the A-F cyclic plasticity model and the incremental Neuber's rule. On the basis of the multiaxial local stress-strain state and a critical plane based multiaxial fatigue damage criterion, the fatigue damage of the notched components was analyzed and then the fatigue life was predicted. The numerical results show that the proposed multiaxial local stress-strain method can describe the multiaxial stress state at the notch root very well, and the predicted fatigue lives correlate well with the experimental data.

  2. Children’s responses to advergames: the role of game and child characteristics

    van Reijmersdal, E.; Rozendaal, E.; Buijzen, M.; Eisend, M.; Langner, T.


    This study examined the effects of three factors typically associated with advergames: brand prominence, game involvement, and children’s (limited) persuasion knowledge on cognitive and affective responses. An experiment among 7 to 12 year old children (N = 104) showed that brand prominence led to i

  3. Children’s responses to advergames: the role of game and child characteristics

    van Reijmersdal, E.; Rozendaal, E.; Buijzen, M.; Eisend, M.; Langner, T.


    This study examined the effects of three factors typically associated with advergames: brand prominence, game involvement, and children’s (limited) persuasion knowledge on cognitive and affective responses. An experiment among 7 to 12 year old children (N = 104) showed that brand prominence led to

  4. The dynamic characteristics of the mouse horizontal vestibulo-ocular and optokinetic response

    A.M. van Alphen (Arjan); J.S. Stahl (J.); C.I. de Zeeuw (Chris)


    textabstractIn the present study the optokinetic reflex, vestibulo-ocular reflex and their interaction were investigated in the mouse, using a modified subconjunctival search coil technique. Gain of the ocular response to sinusoidal optokinetic stimulation was relatively constant for peak velocities

  5. Exploring the Relationship between Cognitive Characteristics and Responsiveness to a Tier 3 Reading Fluency Intervention

    Field, Stacey Allyson


    Current research suggests that certain cognitive functions predict the likelihood of intervention response for students who receive Tier 2 instruction through an RTI-framework. However, less is known about cognitive predictors of responder status at a theoretically more critical point of divergence within the RTI model: Tier 3. Moreover, no…

  6. Dose-response characteristics of ketamine effect on locomotion, cognitive function and central neuronal activity

    Imre, G; Fokkema, DS; Den Boer, JA; Ter Horst, GJ


    The present dose-response study sought to determine the effects of subanesthetic dosages (4-16 mg/kg) of ketamine on locomotion, sensorimotor gating (PP1), working memory, as well as c-fos expression in various limbic regions implicated in the pathogenesis of schizophrenia. In addition, we examined

  7. The dynamic characteristics of the mouse horizontal vestibulo-ocular and optokinetic response

    A.M. van Alphen (Arjan); J.S. Stahl (J.); C.I. de Zeeuw (Chris)


    textabstractIn the present study the optokinetic reflex, vestibulo-ocular reflex and their interaction were investigated in the mouse, using a modified subconjunctival search coil technique. Gain of the ocular response to sinusoidal optokinetic stimulation was relatively constant for peak velocities

  8. Exploring the Relationship between Cognitive Characteristics and Responsiveness to a Tier 3 Reading Fluency Intervention

    Field, Stacey Allyson


    Current research suggests that certain cognitive functions predict the likelihood of intervention response for students who receive Tier 2 instruction through an RTI-framework. However, less is known about cognitive predictors of responder status at a theoretically more critical point of divergence within the RTI model: Tier 3. Moreover, no…

  9. Characteristics of Items in the Eysenck Personality Inventory Which Affect Responses When Students Simulate

    Power, R. P.; Macrae, K. D.


    A large sample of students completed Form A of the Eysenck Personality Inventory, and four subgroups were later asked to simulate extraversion, introversion, neuroticism or stability. It was found that subjects could simulate these four personalities successfully. The changes in individual item responses were correlated with the items' factor…

  10. Chicken retinal ganglion cells response characteristics: multi-channel electrode recording study

    CHEN; Aihua; (陈爱华); ZHOU; Yi(周; 艺); GONG; Haiqing; (龚海庆); LIANG; Peiji; (梁培基)


    The first stage of visual processing occurs in the retina, the function of which is to process the raw information obtained from the outside world. In the present study, the electrical activities of a group of retinal ganglion cells were recorded from a small functioning piece of retina, using multi-electrode array (MEA), and the action potentials were detected by applying nonlinear algorithm. By analyzing the ensemble retinal ganglion output characteristics, it is revealed that both firing rates and correlated activity between adjacent neurons in the retina contribute to visual information encoding.


    WuYongdong; ZhongWeifang; LiangYide


    This paper analyzes the characteristics of utilizing shape memory effect (SME) of shape memory alloy (SMA) in improving the low velocity impact resistance performance of composite plate by using finite element method. The constitutive relation for SMA hybrid composite plates is presented. The analytic model of finite element for SMA composite plate subjected to low velocity impact is established. The modified Hertz's contact law is used to determine the impact contact force. The computing procedures for solving the finite element equation using Newmark direct integration method are given. The numerical modelling results show that the SMA can effectively improve the low velocity impact resistance performance of composite plate.

  12. Productive and chemical characteristics of Marandu grass in response to poultry manure and soil chiseling


    ABSTRACT The objective of this study was to evaluate the productive and chemical characteristics of Marandu grass fertilized with poultry manure with or without the use of soil chiseling, during a period of 210 days. The experiment was conducted in a Dark-Red Latosol (Haplustox) of sandy texture, in a randomized block design with 4 replicates, in a 6 x 2 factorial scheme (0, 1.037, 2.074, 4.148, 6.222 t ha-1 of poultry manure and an additional treatment with chemical fertilizer based on 2.074...

  13. Experimental study on the response characteristics of coal permeability to pore pressure under loading and unloading conditions

    Ye, Zhiwei; Zhang, Lei; Hao, Dingyi; Zhang, Cun; Wang, Chen


    In order to study the response characteristics of coal permeability to pore pressure, seepage experiments under different simulated in situ stresses on loading and unloading paths are carried out using the self-developed Gas Flow and Displacement Testing Apparatus (GFDTA) system. Based on the analysis of the experimental data, the relationship between average pore pressure and permeability is found to basically obey the function distribution of a two degree polynomial. In this paper, two aspects of the relationship between permeability and pore pressure are explained: the Klinbenberg effect and expansion, and the penetration of the initial fracture. Under low pore pressure, the decrease in the Klinbenberg effect is the main reason for the decrease in permeability with increased pore pressure. Under relatively high pore pressure, the increase in pore pressure leads to the initial fracture expansion and penetration of the coal sample, which causes an increase in permeability. In order to evaluate the sensitivity of the permeability response to pore pressure changes, the permeability dispersion and pore pressure sensitivity coefficients are defined. After the sensitivity analysis, it was concluded that the loading history changed the fracture structure of the original coal sample and reduced its permeability sensitivity to pore pressure. Under low pore pressure, the Klinbenberg effect is the reason for the decrease in pore pressure sensitivity. Lastly, the permeability-pore pressure relationship is divided into three stages to describe the different response characteristics individually.

  14. A Study on the Response Characteristics of a Fiber-Optic Radiation Sensor Model Based on Cerenkov Principle

    Han, Hwa Jeong; Kim, Beom Kyu; Park, Byung Gi [Soonchunhyang Univ., Asan (Korea, Republic of)


    In recent year, various fiber-optic radiation sensors using Cerenkov principle have been developed without employing any scintillators for measuring high-energy photon, electron, etc. The main advantages of the optical fibers are the remote transmission of the light signal and immunity to pressure and electromagnetic waves. Therefore, the sensors utilizing the optical fibers can be used in hazardous radiation environments, such as the high-level radiation areas of a nuclear facility. The study to be simulated a fiber-optic radiation sensor based on Cerenkov principle and to be analyzed the response characteristics of the sensor. For the aforementioned study, the GEANT simulation toolkit was used. It is able to take into all the optical properties of fibers and is found to be appropriate to realistically describe the response of fiber-optic radiation sensor. In the recently, the fiber-optic radiation sensor have been developed in nuclear industry. Because sensor can detect gamma ray in harsh nuclear environments. In this study, we analyzed response characteristics of the fiber-optic radiation sensor. We have simulated the Monte Carlo model, for detecting the Cerenkov radiation using the fiber-optic radiation sensor. And the y-axis distribution of Cerenkov photons was obtained using output file. Simulation is performed with reference to the method of the previous research, and then the simulation results exhibited a good agreement with the previous research.

  15. Surfactant effect on functionalized carbon nanotube coated snowman-like particles and their electro-responsive characteristics

    Zhang, Ke; Liu, Ying Dan [Department of Polymer Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of); Choi, Hyoung Jin, E-mail: [Department of Polymer Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of)


    The core–shell structured snowman-like (SL) microparticles coated by functionalized multi-walled carbon nanotube (MWNT) were prepared in the presence of different surfactants including cationic surfactant-cetyl trimethylammonium bromide (CTAB) and anionic surfactant-sodium lauryl sulfate (SDS). The effect of surfactants on adsorption onto SL particles was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and conductivity. The cationic surfactant is found to be more effective than anionic surfactant for helping nanotube adsorbed onto microparticle due to the presence of electrostatic interaction between the functionalized MWNT and the surfactant. Furthermore, the MWNT/SL particles dispersed in silicone oil exhibited a typical fibril structure of the electrorheological characteristics under an applied electric field observed by an optical microscope (OM), in which the state of nanotubes wrapped on the particles strongly affects their electro-responsive characteristics.

  16. Study on ground temperature change and characteristic response of engineering geology of permafrost along Qinghai-Tibet Railway

    PAN Weidong; WANG Quancai; YU Shaoshui; ZHANG Xiaoyan


    Along with the global warming in the recent scores of years, comparatively big changes have taken place in the weather and other environmental conditions of the permafrost area in the Qinghai-Tibet Plateau, and very big changes have also occurred in the engineering geological conditions of the permafrost area. Based on a large volume of field survey data, this paper discusses the regularities of horizontal and vertical distribution of permafrost, with its focus of analysis on the temperature change characteristics of the soil in different frozen-soil zones, as well as presents simulation analysis and research for the engineering geologic characteristic response changes that would occur in the future when the temperature of the frozen soil in different zones rises by 1 and 2.6℃ respectively, which will have a tremendous impact on the stability of constructional work.

  17. Dose response characteristics of a novel CCD camera-based electronic portal imaging device comparison with OCTAVIUS detector.

    Anvari, Akbar; Aghamiri, Seyed Mahmoud Reza; Mahdavi, Seyed Rabie; Alaei, Parham


    Dosimetric properties of a CCD camera-based Electronic Portal Imaging Device (EPID) for clinical dosimetric application have been evaluated. Characteristics obtained by EPID also compared with commercial 2D array of ion chambers. Portal images acquired in dosimetry mode then exported raw fluence or uncorrected images were investigated. Integration time of image acquisition mode has adjusted on 1 s per frame. As saturation of camera of the EPID, dose response does not have linear behavior. The slight nonlinearity of the camera response can be corrected by a logarithmic expression. A fourth order polynomial regression model with coefficient of determination of 0.998 predicts a response to absolute dose values at less than 50 cGy. A field size dependent response of up to 7% (0.99-1.06) relative OCTAVIUS detector measurement was found. The EPID response can be fitted by a cubic regression for field size changes, yielded coefficient of determination of 0.999. These results indicate that the EPID is well suited for accurate dosimetric purposes, the major limitation currently being due to integration time and dead-time in frame acquisition.

  18. The Red Herring technique: a methodological response to the problem of demand characteristics.

    Laney, Cara; Kaasa, Suzanne O; Morris, Erin K; Berkowitz, Shari R; Bernstein, Daniel M; Loftus, Elizabeth F


    In past research, we planted false memories for food related childhood events using a simple false feedback procedure. Some critics have worried that our findings may be due to demand characteristics. In the present studies, we developed a novel procedure designed to reduce the influence of demand characteristics by providing an alternate magnet for subjects' natural suspicions. We used two separate levels of deception. In addition to giving subjects a typical untrue rationale for the study (i.e., normal deceptive cover story), we built in strong indicators (the "Red Herring") that the study actually had another purpose. Later, we told subjects that we had deceived them, and asked what they believed the "real purpose" of the study was. We also interviewed a subset of subjects in depth in order to analyze their subjective experiences of the procedure and any relevant demand. Our Red Herring successfully tricked subjects, and left little worry that our false memory results were due to demand. This "double cross" technique may have widespread uses in psychological research that hopes to conceal its real hypotheses from experimental subjects.

  19. Responses of herbaceous plants to urban air pollution: effects on growth, phenology and leaf surface characteristics.

    Honour, Sarah L; Bell, J Nigel B; Ashenden, Trevor W; Cape, J Neil; Power, Sally A


    Vehicle exhaust emissions are a dominant feature of urban environments and are widely believed to have detrimental effects on plants. The effects of diesel exhaust emissions on 12 herbaceous species were studied with respect to growth, flower development, leaf senescence and leaf surface wax characteristics. A diesel generator was used to produce concentrations of nitrogen oxides (NO(x)) representative of urban conditions, in solardome chambers. Annual mean NO(x) concentrations ranged from 77 nl l(-l) to 98 nl l(-1), with NO:NO(2) ratios of 1.4-2.2, providing a good experimental simulation of polluted roadside environments. Pollutant exposure resulted in species-specific changes in growth and phenology, with a consistent trend for accelerated senescence and delayed flowering. Leaf surface characteristics were also affected; contact angle measurements indicated changes in surface wax structure following pollutant exposure. The study demonstrated clearly the potential for realistic levels of vehicle exhaust pollution to have direct adverse effects on urban vegetation.

  20. Response characteristics of soil fractal features to different land uses in typical purple soil watershed.

    Luo, Bang-lin; Chen, Xiao-yan; Ding, Lin-qiao; Huang, Yu-han; Zhou, Ji; Yang, Tian-tian


    As a fundamental characteristic of soil physical properties, the soil Particle Size Distribution (PSD) is important in the research on soil moisture migration, solution transformation, and soil erosion. In this research, the PSD characteristics with distinct methods in different land uses are analyzed. The results show that the upper bound of the volume domain of the clay domain ranges from 5.743 μm to 5.749 μm for all land-use types. For the silt domain of purple soil, the value ranges among 286.852~286.966 μm. For all purple soil land-use types, the order of the volume domain fractal dimensions is D claysoil properties shows that the intensity of correlation to the soil texture and soil organic matter has the order as: D silt>D silt(U)>D sand (U)>D sand and D silt>D silt(U)>D sand>D sand(U), respectively. As it is compared with all Dvi, the D silt has the most significant correlativity to the soil texture and organic matter in different land uses of the typical purple soil watersheds. Therefore, Dsilt will be a potential indictor for evaluating the proportion of fine particles in the PSD, as well as a key measurement in soil quality and productivity studies.

  1. Response characteristics of soil fractal features to different land uses in typical purple soil watershed.

    Bang-lin Luo

    Full Text Available As a fundamental characteristic of soil physical properties, the soil Particle Size Distribution (PSD is important in the research on soil moisture migration, solution transformation, and soil erosion. In this research, the PSD characteristics with distinct methods in different land uses are analyzed. The results show that the upper bound of the volume domain of the clay domain ranges from 5.743 μm to 5.749 μm for all land-use types. For the silt domain of purple soil, the value ranges among 286.852~286.966 μm. For all purple soil land-use types, the order of the volume domain fractal dimensions is D clayD silt(U>D sand (U>D sand and D silt>D silt(U>D sand>D sand(U, respectively. As it is compared with all Dvi, the D silt has the most significant correlativity to the soil texture and organic matter in different land uses of the typical purple soil watersheds. Therefore, Dsilt will be a potential indictor for evaluating the proportion of fine particles in the PSD, as well as a key measurement in soil quality and productivity studies.

  2. Studies on responsiveness of hepatoma cells to catecholamines. VI. Characteristics of adrenoceptors and adenylate cyclase response in rat ascites hepatoma cells and human hepatoma cells.

    Sanae, F; Kohei, K; Nomura, M; Miyamoto, K


    Alpha 1, alpha 2- and beta-Adrenoceptor densities and catecholamine responsiveness in established hepatoma cells, rat ascites hepatoma AH13, AH66, AH66F, AH109A, AH130 and AH7974 cells and human hepatocellular carcinoma HLF and HepG2 cells, were compared with those in normal rat hepatocytes and Chang liver cells. Alpha 1-Adrenoceptor densities measured by [3H]prazosin bindings were not detected in all hepatoma cell lines. Alpha 2-Adrenoceptor densities measured by [3H]clonidine bindings were also barely detected in hepatoma cell lines except for AH130 cells and HepG2 cells. Regarding beta-adrenoceptor, AH109A, AH130 and AH7974 cells had much more [125I]iodocyanopindolol binding sites than normal rat hepatocytes, although we could not detect the binding in HepG2 cells. Adenylate cyclase of normal rat hepatocyte and Chang liver cells were stimulated by beta 2-adrenergic agonist salbutamol, while the cyclase in hepatoma cells had no beta 2-adrenergic response but a beta 1-type response. These findings indicate that the characteristics of adrenergic response in hepatoma cell lines is very different from that in normal hepatocytes, suggesting a participation in the hepatocarcinogenesis and/or the autonomous proliferation of hepatoma cells.

  3. The Genetic Influences on Oxycodone Response Characteristics in Human Experimental Pain

    Olesen, Anne Estrup; Sato, Hiroe; Nielsen, Lecia Møller


    PTT (n = 41) were included. Genetic associations with pain outcomes were explored. Nineteen opioid receptor genetic polymorphisms were included in this study. Variability in oxycodone response to skin heat was associated with OPRM1 single-nucleotide polymorphisms (SNPs) rs589046 (P ...Human experimental pain studies are of value to study basic pain mechanisms under controlled conditions. The aim of this study was to investigate whether genetic variation across selected mu-, kappa- and delta-opioid receptor genes (OPRM1, OPRK1and OPRD1, respectively) influenced analgesic response...... to oxycodone in healthy volunteers. Experimental multimodal, multitissue pain data from previously published studies carried out in Caucasian volunteers were used. Data on thermal skin pain tolerance threshold (PTT) (n = 37), muscle pressure PTT (n = 31), mechanical visceral PTT (n = 43) and thermal visceral...

  4. The impact of maternal characteristics, infant temperament and contextual factors on maternal responsiveness to infant.

    Tester-Jones, Michelle; O'Mahen, Heather; Watkins, Edward; Karl, Anke


    Postnatal maternal depressive symptoms are consistently associated with impairments in maternal attunement (i.e., maternal responsiveness and bonding). There is a growing body of literature examining the impact of maternal cognitive factors (e.g., rumination) on maternal attunement and mood. However, little research has examined the role of infant temperament and maternal social support in this relationship. This study investigated the hypothesis that rumination would mediate (1) the relationship between depressive symptoms and attunement and (2) the relationship between social support and attunement. We further predicted that infant temperament would moderate these relationships, such that rumination would demonstrate mediating effects on attunement when infant difficult temperament was high, but not low. Two hundred and three mothers completed measures on rumination, depressive symptoms, attunement, perceived social support and infant temperament. Rumination mediated the effect of postnatal maternal depressive mood on maternal self-reported responsiveness to the infant when infants were low, but not high, in negative temperament. When infants had higher negative temperament, there were direct relationships between maternal depressive symptoms, social support and maternal self-reported responsiveness to the infant. This study is limited by its cross-sectional and correlational nature and the use of self-report measures to assess a mother's awareness of her infant needs and behaviours, rather than observational measures of maternal sensitivity. These findings suggest potentially different pathways to poor maternal responsiveness than those expected and provide new evidence about the contexts in which maternal cognitive factors, such as rumination, may impact on the mother-infant relationship.

  5. Mechanically stable nanostructures with desirable characteristic field enhancement factors: a response from scale invariance in electrostatics

    de Assis, Thiago A.; Dall'Agnol, Fernando F.


    This work presents an accurate numerical study of the electrostatics of a system formed by individual nanostructures mounted on support substrate tips, which provides a theoretical prototype for applications in field electron emission or for the construction of tips in probe microscopy that requires high resolution. The aim is to describe the conditions to produce structures mechanically robust with desirable field enhancement factor (FEF). We modeled a substrate tip with a height h 1, radius r 1 and characteristic FEF {γ }1, and a top nanostructure with a height h 2, radius {r}2\\lt {r}1 and FEF {γ }2, for both hemispheres on post-like structures. The nanostructure mounted on the support substrate tip then has a characteristic FEF, {γ }{{C}}. Defining the relative difference {η }{{R}}=({γ }{{C}}-{γ }1)/({γ }3-{γ }1), where {γ }3 corresponds to the reference FEF for a hemisphere of the post structure with a radius {r}3={r}2 and height {h}3={h}1+{h}2, our results show, from a numerical solution of Laplace’s equation using a finite element scheme, a scaling {η }{{R}}=f(u\\equiv λ {θ }-1), where λ \\equiv {h}2/{h}1 and θ ={r}1/{r}2. Given a characteristic variable u c, for u\\ll {u}{{c}}, we found a power law {η }{{R}}˜ {u}κ , with κ ≈ 0.55. For u\\gg {u}{{c}}, {η }{{R}}\\to 1, which led to conditions where {γ }{{C}}\\to {γ }3. As a consequence of scale invariance, it is possible to derive a simple expression for {γ }{{C}} and to predict the conditions needed to produce related systems with a desirable FEF that are robust owing to the presence of the substrate tip. Finally, we discuss the validity of Schottky’s conjecture (SC) for these systems, showing that, while to obey SC is indicative of scale invariance, the opposite is not necessarily true. This result suggests that a careful analysis must be performed before attributing SC as an origin of giant FEF in experiments.

  6. Engineering characteristics of near-fault vertical ground motions and their effect on the seismic response of bridges

    Li Xinle; Dou Huijuan; Zhu Xi


    A wide variety of near-fault strong ground motion records were collected from various tectonic environments worldwide and were used to study the peak value ratio and response spectrum ratio of the vertical to horizontal component of ground motion,focusing on the effect of earthquake magnitude,site conditions,pulse duration,and statistical component.The results show that both the peak value ratio and response spectrum ratio are larger than the 2/3 value prescribed in existing seismic codes,and the relationship between the vertical and horizontal ground motions is comparatively intricate.In addition,the effect of the near-fault ground motions on bridge performance is analyzed,considering both the material nonlinear characteristics and the P~△ effect.

  7. Elastic-plastic contact force history and response characteristics of circular plate subjected to impact by a projectile

    L. B. Chen; F. Xi; J. L. Yang


    A new elastic-plastic impact-contact model is proposed in this paper. By adopting the principle of minimum acceleration for elastic-plastic continue at finite deformation,and with the aid of finite difference method, the proposed model is applied in the problem of dynamic response of a clamped thin circular plate subjected to a projectile impact centrally. The impact force history and response characte-ristics of the target plate is studied in detail. The theoreti-cal predictions of the impact force and plate deflection are in good agreements with those of LDA experimental data.Linear expressions of the maximum impact force/transverse deflection versus impact velocity are given on the basis of the theoretical results.


    曹耿; 阿肯江.托呼提


    Compressive strength and stress-strain curve were investigated and probed by test of basic mechanical properties of adobe masonry. Based on experimental study and theoretical analysis, the fraction equation are put forward to simulate uniaxial compression stress-strain curve of adobe masonry, the uniaxial compression constitutive equation is established, the fitted value and specific physical meaning of parameters in constitutive equation is assigned. These works can also provide parameters in order to analyse the seismic performance of adobe masonry houses.%通过对土坯砌体试件进行基本力学性能试验,就其抗压强度及应力-应变关系进行了研究和探讨,在试验研究与理论分析的基础上采用分式方程拟合了土坯砌体单轴受压应力-应变曲线,建立其单轴受压本构方程,给出了本构方程中参数的拟合值和明确的物理意义,研究成果可为土坯砌体房屋抗震性能分析提供参考.

  9. Frequency characteristics of human muscle and cortical responses evoked by noisy Achilles tendon vibration.

    Mildren, Robyn Lynne; Peters, Ryan M; Hill, Aimee J; Blouin, Jean-Sebastien; Carpenter, Mark Gregory; Inglis, J Timothy


    Noisy stimuli, along with linear systems analysis, have proven to be effective for mapping functional neural connections. We explored the use of noisy (10-115 Hz) Achilles tendon vibration to examine proprioceptive reflexes in the triceps surae muscles in standing healthy young adults (n = 8). We also examined the association between noisy vibration and electrical activity recorded over the sensorimotor cortex using electroencephalography. We applied two-minutes of vibration and recorded ongoing muscle activity of the soleus and gastrocnemii using surface electromyography (EMG). Vibration amplitude was varied to characterize reflex scaling and to examine how different stimulus levels affected postural sway. Muscle activity from the soleus and gastrocnemii were significantly correlated with the tendon vibration across a broad frequency range (~10-80 Hz), with a peak located at ~40 Hz. Vibration-EMG coherence positively scaled with stimulus amplitude in all three muscles, with soleus displaying the strongest coupling and steepest scaling. EMG responses lagged the vibration by ~38 ms, a delay that paralleled observed response latencies to tendon taps. Vibration-evoked cortical oscillations were observed at frequencies ~40-70 Hz (peak ~54 Hz) in most subjects, a finding in line with previous reports of sensory evoked γ-band oscillations. Further examination of the method revealed a) accurate reflex estimates could be obtained with <60 s of low-level (RMS=10 m/s(2)) vibration, b) responses did not habituate over two-minutes of exposure, and importantly c) noisy vibration had a minimal influence on standing balance. Our findings suggest noisy tendon vibration is an effective novel approach to characterize proprioceptive reflexes.

  10. Investigation of anal motor characteristics of the sensorimotor response (SMR) using 3-D anorectal pressure topography

    Cheeney, Gregory; Remes-Troche, Jose M.; Attaluri, Ashok


    Desire to defecate is associated with a unique anal contractile response, the sensorimotor response (SMR). However, the precise muscle(s) involved is not known. We aimed to examine the role of external and internal anal sphincter and the puborectalis muscle in the genesis of SMR. Anorectal 3-D pressure topography was performed in 10 healthy subjects during graded rectal balloon distention using a novel high-definition manometry system consisting of a probe with 256 pressure sensors arranged circumferentially. The anal pressure changes before, during, and after the onset of SMR were measured at every millimeter along the length of anal canal and in 3-D by dividing the anal canal into 4 × 2.1-mm grids. Pressures were assessed in the longitudinal and anterior-posterior axis. Anal ultrasound was performed to assess puborectalis morphology. 3-D topography demonstrated that rectal distention produced an SMR coinciding with desire to defecate and predominantly induced by contraction of puborectalis. Anal ultrasound showed that the puborectalis was located at mean distance of 3.5 cm from anal verge, which corresponded with peak pressure difference between the anterior and posterior vectors observed at 3.4 cm with 3-D topography (r = 0.77). The highest absolute and percentage increases in pressure during SMR were seen in the superior-posterior portion of anal canal, reaffirming the role of puborectalis. The SMR anal pressure profile showed a peak pressure at 1.6 cm from anal verge in the anterior and posterior vectors and distinct increase in pressure only posteriorly at 3.2 cm corresponding to puborectalis. We concluded that SMR is primarily induced by the activation and contraction of the puborectalis muscle in response to a sensation of a desire to defecate. PMID:21109594

  11. Gene profiling characteristics of radioadaptive response in AG01522 normal human fibroblasts.

    Jue Hou

    Full Text Available Radioadaptive response (RAR in mammalian cells refers to the phenomenon where a low-dose ionizing irradiation alters the gene expression profiles, and protects the cells from the detrimental effects of a subsequent high dose exposure. Despite the completion of numerous experimental studies on RAR, the underlying mechanism has remained unclear. In this study, we aimed to have a comprehensive investigation on the RAR induced in the AG01522 human fibroblasts first exposed to 5 cGy (priming dose and then followed by 2 Gy (challenge dose of X-ray through comparisons to those cells that had only received a single 2 Gy dose. We studied how the priming dose affected the expression of gene transcripts, and to identify transcripts or pathways that were associated with the reduced chromosomal damages (in terms of the number of micronuclei after application of the challenging dose. Through the mRNA and microRNA microarray analyses, the transcriptome alteration in AG01522 cells was examined, and the significantly altered genes were identified for different irradiation procedures using bioinformatics approaches. We observed that a low-dose X-ray exposure produced an alert, triggering and altering cellular responses to defend against subsequent high dose-induced damages, and accelerating the cell repair process. Moreover, the p53 signaling pathway was found to play critial roles in regulating DNA damage responses at the early stage after application of the challenging dose, particularly in the RAR group. Furthermore, microRNA analyses also revealed that cell communication and intercellular signaling transduction played important roles after low-dose irradiation. We conclude that RAR benefits from the alarm mechanisms triggered by a low-dose priming radation dose.

  12. Physiological responses and match characteristics in professional tennis players during a one-hour simulated tennis match

    Kilit Bülent


    Full Text Available The purpose of this study was to investigate the effects of serve and return game situations on physiological responses and match characteristics in professional male tennis players during one hour-long simulated singles tennis matches. Ten internationally ranked tennis players (age 22.2 ± 2.8 years; body height 180.7 ± 4.4 cm; body mass 75.9 ± 8.9 kg participated in this study. Their physiological responses were measured using two portable analyzers during indoor hard court matches. Ratings of perceived exertion were also determined at the end of the game. The variables describing the characteristics of the matches determined from video recordings were: (a duration of rallies; (b rest time; (c work-to-rest ratio; (d effective playing time; and (d strokes per rally. Significant differences (p<0.05 were found between serving and returning conditions in an hour-long simulated singles tennis match in terms of oxygen uptake, a heart rate, ratings of perceived exertion, pulmonary ventilation, respiration frequency and a respiratory gas exchange ratio. In addition, both the heart rate and ratings of perceived exertion responses were moderately correlated with the duration of rallies and strokes per rally (r = 0.60 to 0.26; p<0.05. Taken together, these results indicate that the serve game situation has a significant effect on the physiological response in an hour-long simulated tennis match between professional male tennis players. These findings might be used for the physiological adaptations required for tennis-specific aerobic endurance.

  13. Effect of dietary selenium and vitamin E on ganders' response to semen collection and ejaculate characteristics.

    Jerysz, Anna; Lukaszewicz, Ewa


    Compared to other domestic bird species, geese exhibit the lowest reproductive efficiency (poor semen quality, low egg production, and poor fertility and hatchability rates). From an economic perspective, it is a necessity of improve these reproductive traits. Studies have demonstrated that the essential trace element-selenium-plays key roles in testicular development and the maintenance of spermatogenesis. The aim of the present study was to determine the effect of feed supplementation with organic selenium and vitamin E on ganders' response to manual semen collection and semen quality. Sixteen 3-year-old White Koluda ganders were randomly divided into two groups. The control group was provided commercial feed while the experimental group was provided with the same commercial feed supplemented with selenium (0.3 mg/kg) and vitamin E (100 mg/kg). The response of individual ganders from both groups to manual semen collection and the quality of the semen collected were evaluated. The supplements increased (P ≤ 0.05) the frequency and decreased the time interval of a complete ejaculatory response of the ganders to manual semen collections (82.7 % supplement vs. 73.5 % control). Males from the supplemented group had significantly higher (P ≤ 0.01; P ≤ 0.05) ejaculate volumes, sperm concentrations, and percentages of viable sperm and lower percentages of immature sperm (spermatids). Lipids peroxidation, expressed in terms of the malondialdehyde concentration, was lower (P ≤ 0.01) in semen of the supplemented group (0.172 nmol/50 × 10(6)) as compared to the controls (0.320 nmol/50 × 10(6)). Moreover, the duration of the reproductive period of the ganders in the experimental group was 1 week longer. The results show that supplemental dietary selenium and vitamin E improved both the ganders' response to manual semen collection and semen quality. We conclude that such feed supplementation could lead to greater economic benefits

  14. The biological mechanisms and physicochemical characteristics responsible for driving fullerene toxicity.

    Johnston, Helinor J; Hutchison, Gary R; Christensen, Frans M; Aschberger, Karin; Stone, Vicki


    This review provides a comprehensive critical review of the available literature purporting to assess the toxicity of carbon fullerenes. This is required as prior to the widespread utilization and production of fullerenes, it is necessary to consider the implications of exposure for human health. Traditionally, fullerenes are formed from 60 carbon atoms, arranged in a spherical cage-like structure. However, manipulation of surface chemistry and molecular makeup has created a diverse population of fullerenes, which exhibit drastically different behaviors. The cellular processes that underlie observed fullerene toxicity will be discussed and include oxidative, genotoxic, and cytotoxic responses. The antioxidant/cytoprotective properties of fullerenes (and the attributes responsible for driving these phenomena) have been considered and encourage their utilization within the treatment of oxidant-mediated disease. A number of studies have focused on improving the water solubility of fullerenes in order to enable their exploitation within biological systems. Manipulating fullerene water solubility has included the use of surface modifications, solvents, extended stirring, and mechanical processes. However, the ability of these processes to also impact on fullerene toxicity requires assessment, especially when considering the use of solvents, which particularly appear to enhance fullerene toxicity. A number of the discussed investigations were not conducted to reveal if fullerene behavior was due to their nanoparticle dimensions but instead addressed the biocompatibility and toxicity of fullerenes. The hazards to human health, associated with fullerene exposure, are uncertain at this time, and further investigations are required to decipher such effects before an effective risk assessment can be conducted.

  15. Bilateral nature of the conditioned eyeblink response in the rabbit: behavioral characteristics and potential mechanisms.

    Lee, Taekwan; Kim, Jeansok J; Wagner, Allan R


    In Pavlovian eyeblink conditioning, the conditioned response (CR) is highly lateralized to the eye to which the unconditioned stimulus (US) has been directed. However, the initial conditioning of one eye can facilitate subsequent conditioning of the other eye, a phenomenon known as the intereye transfer (IET) effect. Because a conditioned emotional response (CER), as well as the eyeblink CR, is acquired during eyeblink conditioning and influences the development of the CR, the CER acquired in initial training can plausibly account for the IET effect. To evaluate this possibility, the present study utilized previously determined eyeblink conditioning procedures that effectively decouple the degree of CER and CR development to investigate the IET effect. In each of 3 experiments rabbits were initially trained with comparison procedures that differentially favored the development of the eyeblink CR or the CER, prior to a shift of the US to the alternate eye. The observed differences in the IET suggest that the effect depends largely on the specific development of eyeblink CRs rather than the CER. The neurobiological implications of this apparent bilaterality of the eyeblink CR are discussed.

  16. Work capacity and metabolic and morphologic characteristics of the human quadriceps muscle in response to unloading

    Berg, H. E.; Dudley, G. A.; Hather, B.; Tesch, P. A.


    The response of skeletal muscle to unweighting was studied in six healthy males who were subjected to four weeks of lowerlimb suspension. They performed three bouts of 30 consecutive maximal concentric knee extensions, before unloading and the day after (POST 1), 4 days after (POST 2) and 7 weeks after (REC) resumed weight-bearing. Peak torque of each contraction was recorded and work was calculated as the mean of the average peak torque for the three bouts and fatigability was measured as the decline in average peak torque over bouts. Needle biopsies were obtained from m. vastus lateralis of each limb before and at POST 1. Muscle fibre type composition and area, capillarity and the enzyme activities of citrate synthase (CS) and phosphofructokinase (PFK) were subsequently analysed. Mean average peak torque for the three bouts at POST1, POST2 and REC was reduced (P 0.05) in response to unloading. The activity of CS, but not PFK, decreased (P < 0.05) after unloading. The weight-bearing limb showed no changes in the variables measured. The results of this study suggest that this human lowerlimb suspension model produces substantial impairments of work and oxidative capacity of skeletal muscle. The performance decrements are most likely induced by lack of weight-bearing.

  17. Structural and textural characteristics of slate and its response to the point load test

    Ana Mladenovič


    Full Text Available From the geomechanical point of view slate is considered to be one of more trying rock varieties. The results of research have shown close relationship between structural, textural and mineralogical characteristics on the one hand, and its strength and resistance to point loads on the other hand. Its weakened zones are the result of anisotropy. They develop mainly due to dynamo-metamorphosis of the primary mudstone, resulting in the formation of the secondary slaty cleavage, with a pronounced preferred orientation of the hyllosilicates. Low strength is the consequence of the weak Van der Waals chemical bond between individual packets of the internal crystal structure of the sheet minerals, particularly sericite. Bedding and microfolds with a crenulated structure and partial preferred orientation of sheet minerals, as well as directions that are weakened with sigmoidal shear deformations as the predecessors of microfaults, also result in significant but less problematicanisotropy. Thin lepidoblastic lamina, in apparently massive sandy metasiltstone beds in the slate represent discontinuities, which have a decisive influence on the reduction of their strength.

  18. Urticarial Dermatitis: Clinical Characteristics of Itch and Therapeutic Response to Cyclosporine

    Kim, Jeong-Min; Lim, Kyung-Min; Kim, Hoon-Soo; Ko, Hyun-Chang; Kim, Moon-Bum


    Background Urticarial dermatitis, which is characterised by persistent wheals with eczematous papules and plaques, is frequently misdiagnosed and difficult to treat. Patients commonly experience intolerable pruritus which may greatly affect their quality of life. Objective The objective of this study is to characterize the clinical patterns of pruritus in patients with urticarial dermatitis and to determine the effectiveness of cyclosporine treatment. Methods This prospective study included 50 histopathologically confirmed patients with urticarial dermatitis. A face-to-face structured questionnaire was given to all patients, and they were treated with low-dose cyclosporine (1~3 mg/kg/d) for at least 2 weeks. Results The majority of patients (80.0%) had moderate to severe pruritus. Most patients experienced exacerbation of the itch in the evening (74.0%), with the extremities (upper, 86.0%; lower, 94.0%) being the most commonly involved sites. Due to severe pruritus, patients complained about reduced social contact, quality of life and difficulties in falling asleep et al. Cyclosporine significantly reduced the mean itch score and extent of erythema, and improved interference with daily activities and sleep. Conclusion Our study highlights the detailed description and characteristics of pruritus in patients with urticarial dermatitis. And we recommend alternative and effective therapeutic option of low-dose cyclosporine.

  19. Spatiotemporal Characteristics of Groundwater Drought and Its Response to Meteorological Drought in Jiangsu Province, China

    Bo Liu


    Full Text Available In this study, the temporal and spatial variations of groundwater drought using a Standardized Groundwater Level Index (SGI were analyzed based on 40 monthly groundwater level observation wells from 1989 to 2012 in Jiangsu Province, China. Meteorological drought, calculated by the Standardized Precipitation Index (SPI, was also included to reveal its propagation and impact on the groundwater drought process. Results showed that the southern region of Jiangsu faced more frequent groundwater droughts and lower intensity, while the northern region faced less frequent groundwater drought with higher intensity. Furthermore, the cross-correlation between the spatial average of SGI and SPI for SPI accumulation periods of q = 1 to 12 was computed. The relationship between SGI and SPI varied in different regions. Detailed analysis of the characteristics of groundwater and meteorological drought for each region showed that meteorological droughts happened more frequently than groundwater drought in Jiangsu Province during the study period, while the mean duration and mean magnitude of groundwater droughts were longer and larger than those of meteorological droughts. It is expected that this study will provide useful information for drought monitoring and mitigation in Jiangsu and similar areas.

  20. Xylem transcription profiles indicate potential metabolic responses for economically relevant characteristics of Eucalyptus species.

    Salazar, Marcela Mendes; Nascimento, Leandro Costa; Camargo, Eduardo Leal Oliveira; Gonçalves, Danieli Cristina; Lepikson Neto, Jorge; Marques, Wesley Leoricy; Teixeira, Paulo José Pereira Lima; Mieczkowski, Piotr; Mondego, Jorge Maurício Costa; Carazzolle, Marcelo Falsarella; Deckmann, Ana Carolina; Pereira, Gonçalo Amarante Guimarães


    Eucalyptus is one of the most important sources of industrial cellulose. Three species of this botanical group are intensively used in breeding programs: E. globulus, E. grandis and E. urophylla. E. globulus is adapted to subtropical/temperate areas and is considered a source of high-quality cellulose; E. grandis grows rapidly and is adapted to tropical/subtropical climates; and E. urophylla, though less productive, is considered a source of genes related to robustness. Wood, or secondary xylem, results from cambium vascular differentiation and is mostly composed of cellulose, lignin and hemicelluloses. In this study, the xylem transcriptomes of the three Eucalyptus species were investigated in order to provide insights on the particularities presented by each of these species. Data analysis showed that (1) most Eucalyptus genes are expressed in xylem; (2) most genes expressed in species-specific way constitutes genes with unknown functions and are interesting targets for future studies; (3) relevant differences were observed in the phenylpropanoid pathway: E. grandis xylem presents higher expression of genes involved in lignin formation whereas E. urophylla seems to deviates the pathway towards flavonoid formation; (4) stress-related genes are considerably more expressed in E. urophylla, suggesting that these genes may contribute to its robustness. The comparison of these three transcriptomes indicates the molecular signatures underlying some of their distinct wood characteristics. This information may contribute to the understanding of xylogenesis, thus increasing the potential of genetic engineering approaches aiming at the improvement of Eucalyptus forest plantations productivity.

  1. The fuel characteristics of logging residue and their response to storage; Puupolttoaineen laadunvalvonta

    Nurmi, J. [Finnish Forest Research Inst., Kannus (Finland). Kannus Research Station


    Logging residue is one of the major biomass reserves of Finland available for energy production. Some 29 million m{sup 3} of this residue material is left in the forest annually in conjunction with logging operations. The technically harvestable annual reserve is estimated to consist of 8.6 million m{sup 3} biomass needles included, or 5.6 million m{sup 3} needles excluded. The present technology is based on the mechanised harvesting of stemwood with single-grip harvesters, off- road transport of residue to road side with forwarders, chipping at the road side and truck transport of chips. The amount used at heating plants in 1995 was estimated to only 50 000 m{sup 3} solid or less than 1 % of the harvestable reserve. The aim of the Project 125 is to find out how the fuel characteristics and the elemental composition of logging residue change over time in different storage conditions. Based on the information from the first year experiments it can be concluded that the season of comminution is of importance. The enforced paper cover that was used to protect the residue from precipitation did not improve the fuel quality. In addition the release of elements from the needle was found to be very slow. (orig.)

  2. [Response of leaf anatomical characteristics of Cyclobalanopsis gilva seedlings to drought stress].

    Wu, Li-jun; Li, Zhi-hui; Yang, Mo-hua; Wang, Pei-lan


    In this study, the leaf anatomical characteristics and transpiration rate of one-year-old seedlings from three study areas including Qingyuan of Zhejiang Province, Dongkou and Jingzhou of Hunan Province were investigated using a pot planting experiment in which relative soil water content was kept as 75%-80% (control), 55%-60% (mild drought stress), 45%-50% (moderate drought stress), 30%-35% (severe drought stress), respectively. The results showed that drought stress significantly reduced the total thickness of the seedling leaves, the thickness of their upper and lower epidermis and the thickness of palisade tissue. The ratio of the palisade tissue to spongy tissue, stomatal length and width also decreased significantly, while the stomatal density increased significantly as the drought stress became more intense. The treatments of drought stress had no significant effect on the thickness of the main veins of the leaves although their xylem thickness varied depending on the seedlings from the different study sites. The change of leaf structure caused the change of physiological function. As drought stress was intensified, the transpiration rate of C. gilva seedlings decreased significantly. The ratio of the palisade tissue to spongy tissue, the thickness of the lower epidermis and stomatal density of the seedlings from Dongkou of Hunan Province were significantly greater, while the transpiration rate was significantly lower than those from other two study sites for all the drought stress treatments, implying that the C. gilva seedlings from Dongkou of Hunan Province had a stronger drought-resistance ability.

  3. Responses in root physiological characteristics of Vallisneria natans (Hydrocharitaceae to increasing nutrient loadings

    Cai X.


    Full Text Available We selected the submerged macrophyte Vallisneria natans (Lour. Hara for investigating the effects of nutrient loadings (nitrogen (N-phosphorus (P in mg·L-1: (1 0.5, 0.05; (2 1.0, 0.1; (3 5.0, 0.5; (4 10.0, 1.0 on root physiological characteristics using sand culture during the growth season (June to October. Results showed that the best root growth was in macrophytes exposed to moderate nutrient conditions (N-P 2, in 1.0 and 0.10 mg· L-1, and high nutrient loadings induced declines in root growth. Analysis of root antioxidant enzyme (superoxide dismutase (SOD, peroxidase (POD and catalase (CAT activities, protein content and cell ultrastructure revealed that the root of V. natans was subject to the stress of senescence during the end of the growth season. Moreover, high nutrient loadings increased oxidative stress in aging roots of V. natans, and made the cell ultrastructure of roots vulnerable to damage during senescence. The results for the changes in CAT activity suggest that CAT can serve as an important component of antioxidant defense mechanism in aging roots of V. natans to protect against nutrient loading induced oxidative injury in the early period.

  4. Microbial characteristics of purple paddy soil in response to Pb pollution.

    Jiang, Qiu-Ju; Zhang, Yue-Qiang; Zhang, La-Mei; Zhou, Xin-Bin; Shi, Xiao-Jun


    The study focused on the change of microbial characteristics affected by Plumbum pollution with purple paddy soil in an incubation experiment. The results showed that low concentration of Plumbum had little effect on most of microbial amounts, biological activity and enzymatic activity. However, denitrifying activity was inhibited severely, and inhibition rate was up to 98%. Medium and high concentration of Plumbum significantly reduced the amounts and activity of all microorganisms and enzymatic activity, which increased with incubation time. Negative correlations were found between Plumbum concentrations and microbial amounts, biological activity and enzymatic activities except fungi and actinomyces. Thus they can be used to indicate the Plumbum pollution levels to some extent. LD(50) of denitrifying bacteria (DB) and ED50 of denitrifying activity were 852mg/kg and 33.5mg/kg. Across all test soil microbes, denitrifying bacteria was most sensitive to Plumbum pollution in purple paddy soil. Value of early warning showed that anaerobic cellulose-decomposing bacteria (ACDB) and actinomyces were also sensitive to Plumbum pollution. We concluded that denitrifying activity, actinomyces, ACDB or DB can be chosen as predictor of Plumbum contamination in purple paddy soil.

  5. Characteristics of Abnormal Pressure Systems and Their Responses of Fluid in Huatugou Oil Field, Qaidam Basin

    CHEN Xiaozhi; XU Hao; TANG Dazhen; ZHANG Junfeng; HU Xiaolan; TAO Shu; CAI Yidong


    Based on the comprehensive study of core samples, well testing data, and reservoir fluid properties, the construction and the distribution of the abnormal pressure systems of the Huatugou oil field in Qaidam Basin are discussed. The correlation between the pressure systems and hydrocarbon accumulation is addressed by analyzing the corresponding fluid characteristics. The results show that the Huatugou oil field as a whole has low formation pressure and low fluid energy; therefore, the hydrocarbons are hard to migrate, which facilitates the forming of primary reservoirs. The study reservoirs, located at the Xiayoushashan Formation (N_2~1) and the Shangganchaigou Formation (N_1) are relatively shallow and have medium porosity and low permeability. They are abnormal low-pressure reservoirs with an average formation pressure coefficient of 0.61 and 0.72 respectively. According to the pressure coefficient and geothermal anomaly, the N_1 and N_2~1 Formations belong to two independent temperature-pressure systems, and the former has slightly higher energy. The low-pressure compartments consist of a distal bar as the main body, prodeita mud as the top boundary, and shore and shallow lake mud or algal mound as the bottom boundary. They are vertically overlapped and horizontally paralleled. The formation water is abundant in the Cl~- ion and can be categorized as CaCl_2 type with high salinity, which indicates that the abnormal low-pressure compartments are in good sealing condition and beneficial for oil and gas accumulation and preservation.

  6. Productive and chemical characteristics of Marandu grass in response to poultry manure and soil chiseling

    Edson S. Eguchi


    Full Text Available ABSTRACT The objective of this study was to evaluate the productive and chemical characteristics of Marandu grass fertilized with poultry manure with or without the use of soil chiseling, during a period of 210 days. The experiment was conducted in a Dark-Red Latosol (Haplustox of sandy texture, in a randomized block design with 4 replicates, in a 6 x 2 factorial scheme (0, 1.037, 2.074, 4.148, 6.222 t ha-1 of poultry manure and an additional treatment with chemical fertilizer based on 2.074 t ha-1, with and without soil chiseling. Grass-cutting management was performed between 95% of light interception by the canopy and the residual height of 0.15 m. The application of poultry manure resulted in an increase of forage production with higher number of cuts (NC. A linear model described the effect of the applied manure doses on dry matter accumulation (DMA, stems + sheaths (SS and dead material (DM. There was significant interaction between manure doses and soil managements for leaf blade (LB, with greater variations in the treatment without soil chiseling. For plant chemical evaluation, a negative effect of poultry manure was observed on the contents of Ca, Mg, N, S, Mn and Zn, which may be due to the increased number of cuts. Poultry manure positively changed the production of Marandu grass.

  7. Growth characteristics and response to climate change of Larix Miller tree-ring in China


    As one of the earliest species used in dendrochronological studies, Larix responds sensitively to climate change. In this study, nine larch species and one variety from eleven sites were collected to study the growth characteristics of tree-ring width using dendrochronological methods. Ten residual tree-ring chronologies were developed to analyze their relationships with regional standardized anomaly series by Pearson’s correlation analysis. The results suggest that most of the chronologies had significantly positive correlations with the mean temperature and mean maximum temperature in May. The spring temperature evidently limited the radial growth of the larch species without precipitation control. The largest mean tree-ring width was found in Himalayan Larch in Jilong, whereas Master Larch in Si’er reflected the smallest mean value. Both species presented little climate information in this study. Chinese, Potanin, and Tibetan larches are significantly correlated with climate change, implying a huge potential for climate history reconstruction. The elevation of the sampling sites appears to be an important condition for tree-ring growth of larches responding to climate factors.

  8. Identification of PM10 characteristics involved in cellular responses in human bronchial epithelial cells (Beas-2B).

    Van Den Heuvel, Rosette; Den Hond, Elly; Govarts, Eva; Colles, Ann; Koppen, Gudrun; Staelens, Jeroen; Mampaey, Maja; Janssen, Nicole; Schoeters, Greet


    reduction in cell viability was significantly correlated with BC, Cd and Pb. The induction of IL-8 in Beas-2B cells was significantly associated with Cu, Ni and Zn and endotoxin. Endotoxin levels explained 33% of the variance in IL-8 induction. A significant interaction between ambient temperature and endotoxin on the pro-inflammatory activity was seen. No association was found between OP and the cellular responses. This study supports the hypothesis that, on an equal mass basis, PM10 induced biological effects differ due to differences in PM10 characteristics. Metals (Cd, Cu, Ni and Zn), BC, and endotoxin were among the main determinants for the observed biological responses.

  9. Characteristic analysis of the optical delay in frequency response of resonant cavity enhanced (RCE) photodetectors

    Guo Jian-Chuan; Zuo Yu-Hua; Zhang Yun; Ding Wu-Chang; Cheng Bu-Wen; Yu Jin-Zhong; Wang Qi-Ming


    With consideration of the modulation frequency of the input lightwave itself, we present a new model to calculate the quantum efficiency of RCE p-i-n photodetectors (PD) by superimposition of multiple reflected lightwaves. For the first time, the optical delay, another important factor limiting the electrical bandwidth of RCE p-i-n PD excluding the transit time of the carriers and RCd response of the photodetector, is analyzed and discussed in detail. The optical delay dominates the bandwidth of RCE p-i-n PD when its active layer is thinner than several 10 nm. These three limiting factors must be considered exactly for design of ultra-high-speed RCE p-i-n PD.

  10. Responsiveness of cold tolerant chickpea characteristics in fall and spring planting: II. yield and yield components

    ahmad nezami


    Full Text Available Previous research in Mashhad collection chickpeas (MCC has shown that there are some cold tolerant genotypes for fall planting in the highlands. To obtain more detailed information about the reaction of these genotypes to fall and spring planting, the yield and yield component responses of 33 chickpea genotypes (32 cold tolerant genotypes and one susceptible genotypes to four planting dates (28 Sep., 16 Oct., 2 Nov., and 7 Mar. were evaluated in 2000-2001 growing season. The experiment was conducted at the experimental field of college of agriculture, Ferdowsi University of Mashhad as a split plot design with two replications. The planting dates were imposed as main plot and chickpea genotypes as subplot. Effects of planting date and genotype on percent of plant survival (PPS after winter, number. of pod per plant, 100 seed weight, yield and Harvest Index (HI were significant (p

  11. Cellular Responses Evoked by Different Surface Characteristics of Intraosseous Titanium Implants

    Liviu Feller


    Full Text Available The properties of biomaterials, including their surface microstructural topography and their surface chemistry or surface energy/wettability, affect cellular responses such as cell adhesion, proliferation, and migration. The nanotopography of moderately rough implant surfaces enhances the production of biological mediators in the peri-implant microenvironment with consequent recruitment of differentiating osteogenic cells to the implant surface and stimulates osteogenic maturation. Implant surfaces with moderately rough topography and with high surface energy promote osteogenesis, increase the ratio of bone-to-implant contact, and increase the bonding strength of the bone to the implant at the interface. Certain features of implant surface chemistry are also important in enhancing peri-implant bone wound healing. It is the purpose of this paper to review some of the more important features of titanium implant surfaces which have an impact on osseointegration.

  12. A Study on the step response characteristics in shielded resistor divider for full lightning impulse voltage

    Kim, Ik Soo; Lee, Hyeong Ho [Korea Electrotehnology Research Institute, Changwon (Korea, Republic of); Cho, Jung Soo; Park, Jung Hoo [Pusan National University, Pusan (Korea, Republic of)


    This paper presents the development technology of standard shielded resistor divider for full lightning impulse voltage. The ability of large-capacity power apparatus to withstand lighting stroke is usually evaluated by means of full lightning impulse voltage. Lightning impulse voltage test has been essential to evaluate the insulation performance of electrical power apparatus. Recently international standard (IEC 60) on high voltage measurement techniques is being revised and requests a formal traceability of high voltage measurements. Therefore, general interest for this area has grown considerably during last years, and several international intercomparisons have already completed worldwide, i.e. Europe, Japan, America etc., In this viewpoint, we have also investigated the step response of the standard shielded resistor divider, which satisfies the IEC recommendation. (author). 7 refs., 14 figs., 2 tabs.

  13. Comparative Analysis of Seismic Response Characteristics of Pile-Soil-Structure Interaction System


    The study on the earthquake-resistant performance of a pile-soil-structure interaction system is a relatively complicated and primarily important issue in civil engineering practice. In this paper, a computational model and computation procedures for pile-supported structures, which can duly consider the pile-soil interaction effect, are established by the finite element method. Numerical implementation is made in the time domain. A simplified approximation for the seismic response analysis of pile-soil-structure systems is briefly presented. Then a comparative study is performed for an engineering example with numerical results computed respectively by the finite element method and the simplified method. Through comparative analysis, it is shown that the results obtained by the simplified method well agree with those achieved by the finite element method. The numerical results and findings will offer instructive guidelines for earthquake-resistant analysis and design of pile-supported structures.

  14. Expression characteristics of GFP driven by NAC1 promoter and its responses to auxin and gibberellin

    WANG Youhua; DUAN Liusheng; LU Mengzhu; LI Zhaohu; WANG Minjie; ZHAI Zhixi


    A 1050 bp fragment upstream transcription start site of a transcription factor gene NAC1 in Arabidopsis thaliana was amplified and cloned into plasmid pRD420 to construct a green fluorescent protein(GFP) fusion system under the control of NAC1 promoter. Plasmids were introduced into tobacco by Agrobacterium mediated method to regenerate plants with NAC1-GFP gene, and expression pattern of NAC1-GFP and its responses to auxin and gibberellin (GA) were observed. GFP was found to accumulate specifically in root, and was detected after treatment of auxin, N-1-Naphthylphthalamic acid (NPA, an auxin antagonist) or GA3. It was indicated that the expression of GFP driven by NAC1 promoter was induced not only by auxin but also by GAs, suggesting that NAC1 mediated both the auxin signaling and the GAs signaling involved in lateral roots development.

  15. Pharyngeal mis-sequencing in dysphagia: characteristics, rehabilitative response, and etiological speculation.

    Huckabee, Maggie-Lee; Lamvik, Kristin; Jones, Richard


    Clinical data are submitted as documentation of a pathophysiologic feature of dysphagia termed pharyngeal mis-sequencing and to encourage clinicians and researchers to adopt more critical approaches to diagnosis and treatment planning. Recent clinical experience has identified a cohort of patients who present with an atypical dysphagia not specifically described in the literature: mis-sequenced constriction of the pharynx when swallowing. As a result, they are unable to coordinate streamlined bolus transfer from the pharynx into the esophagus. This mis-sequencing contributes to nasal redirection, aspiration, and, for some, the inability to safely tolerate an oral diet. Sixteen patients (8 females, 8 males), with a mean age of 44 years (range=25-78), had an average time post-onset of 23 months (range=2-72) at initiation of intensive rehabilitation. A 3-channel manometric catheter was used to measure pharyngeal pressure. The average peak-to-peak latency between nadir pressures at sensor-1 and sensor-2 was 15 ms (95% CI, -2 to 33 ms), compared to normative mean latency of 239 ms (95% CI, 215 to 263 ms). Rehabilitative responses are summarized, along with a single detailed case report. It is unclear from these data if pharyngeal mis-sequencing is (i) a pathological feature of impaired motor planning from brainstem damage or (ii) a maladaptive compensation developed in response to chronic dysphagia. Future investigation is needed to provide a full report of pharyngeal mis-sequencing, and the implications on our understanding of underlying neural control of swallowing. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Optimized balance rehabilitation training strategy for the elderly through an evaluation of balance characteristics in response to dynamic motions.

    Jung, HoHyun; Chun, Keyoung Jin; Hong, Jaesoo; Lim, Dohyung


    Balance is important in daily activities and essential for maintaining an independent lifestyle in the elderly. Recent studies have shown that balance rehabilitation training can improve the balance ability of the elderly, and diverse balance rehabilitation training equipment has been developed. However, there has been little research into optimized strategies for balance rehabilitation training. To provide an optimized strategy, we analyzed the balance characteristics of participants in response to the rotation of a base plate on multiple axes. Seven male adults with no musculoskeletal or nervous system-related diseases (age: 25.5±1.7 years; height: 173.9±6.4 cm; body mass: 71.3±6.5 kg; body mass index: 23.6±2.4 kg/m(2)) were selected to investigate the balance rehabilitation training using customized rehabilitation equipment. Rotation of the base plate of the equipment was controlled to induce dynamic rotation of participants in the anterior-posterior, right-diagonal, medial-lateral, and left-diagonal directions. We used a three-dimensional motion capture system employing infrared cameras and the Pedar Flexible Insoles System to characterize the major lower-extremity joint angles, center of body mass, and center of pressure. We found statistically significant differences between the changes in joint angles in the lower extremities in response to dynamic rotation of the participants (P0.05). These results indicate that optimizing rotation control of the base plate of balance rehabilitation training equipment to induce anterior-posterior and medial-lateral dynamic rotation preferentially can lead to effective balance training. Additional tests with varied speeds and ranges of angles of base plate rotation are expected to be useful as well as an analysis of the balance characteristics considering a balance index that reflects the muscle activity and cooperative characteristics.

  17. Prostate cancer characteristics associated with response to pre-receptor targeting of the androgen axis.

    Elahe A Mostaghel

    Full Text Available Factors influencing differential responses of prostate tumors to androgen receptor (AR axis-directed therapeutics are poorly understood, and predictors of treatment efficacy are needed. We hypothesized that the efficacy of inhibiting DHT ligand synthesis would associate with intra-tumoral androgen ratios indicative of relative dependence on DHT-mediated growth.We characterized two androgen-sensitive prostate cancer xenograft models after androgen suppression by castration in combination with the SRD5A inhibitor, dutasteride, as well as a panel of castration resistant metastases obtained via rapid autopsy.In LuCaP35 tumors (intra-tumoral T:DHT ratio 2:1 dutasteride suppressed DHT to 0.02 ng/gm and prolonged survival vs. castration alone (337 vs.152 days, HR 2.8, p = 0.0015. In LuCaP96 tumors (T:DHT 10:1, survival was not improved despite similar DHT reduction (0.02 ng/gm. LuCaP35 demonstrated higher expression of steroid biosynthetic enzymes maintaining DHT levels (5-fold higher SRD5A1, 41 fold higher, 99-fold higher RL-HSD, p<0.0001 for both, reconstitution of intra-tumoral DHT (to ∼30% of untreated tumors, and ∼2 fold increased expression of full length AR. In contrast, LuCaP96 demonstrated higher levels of steroid catabolizing enzymes (6.9-fold higher AKR1C2, 3000-fold higher UGT2B15, p = 0.002 and p<0.0001 respectively, persistent suppression of intra-tumoral DHT, and 6-8 fold induction of full length AR and the ligand independent V7 AR splice variant. Human metastases demonstrated bio-active androgen levels and AR full length and AR splice-variant expression consistent with the range observed in xenografts.Intrinsic differences in basal steroidogenesis, as well as variable expression of full length and splice-variant AR, associate with response and resistance to pre-receptor AR ligand suppression. Expression of steroidogenic enzymes and AR isoforms may serve as potential biomarkers of sensitivity to potent AR-axis inhibition and

  18. Comparative characteristics of porous bioceramics for an osteogenic response in vitro and in vivo.

    Lee, Hye-Rim; Kim, Han-Jun; Ko, Ji-Seung; Choi, Yong-Suk; Ahn, Myun-Whan; Kim, Sukyoung; Do, Sun Hee


    Porous calcium phosphate ceramics are used in orthopedic and craniofacial applications to treat bone loss, or in dental applications to replace missing teeth. The implantation of these materials, however, does not induce stem cell differentiation, so suitable additional materials such as porous calcium phosphate discs are needed to influence physicochemical responses or structural changes. Rabbit adipose-derived stem cells (ADSC) and mouse osteoblastic cells (MC3T3-E1) were evaluated in vitro by the MTT assay, semi-quantitative RT-PCR, and immunoblotting using cells cultured in medium supplemented with extracts from bioceramics, including calcium metaphosphate (CMP), hydroxyapatite (HA) and collagen-grafted HA (HA-col). In vivo evaluation of the bone forming capacity of these bioceramics in rat models using femur defects and intramuscular implants for 12 weeks was performed. Histological analysis showed that newly formed stromal-rich tissues were observed in all the implanted regions and that the implants showed positive immunoreaction against type I collagen and alkaline phosphatase (ALP). The intramuscular implant region, in particular, showed strong positive immunoreactivity for both type I collagen and ALP, which was further confirmed by mRNA expression and immunoblotting results, indicating that each bioceramic material enhanced osteogenesis stimulation. These results support our hypothesis that smart bioceramics can induce osteoconduction and osteoinduction in vivo, although mature bone formation, including lacunae, osteocytes, and mineralization, was not prominent until 12 weeks after implantation.

  19. Comparative characteristics of porous bioceramics for an osteogenic response in vitro and in vivo.

    Hye-Rim Lee

    Full Text Available Porous calcium phosphate ceramics are used in orthopedic and craniofacial applications to treat bone loss, or in dental applications to replace missing teeth. The implantation of these materials, however, does not induce stem cell differentiation, so suitable additional materials such as porous calcium phosphate discs are needed to influence physicochemical responses or structural changes. Rabbit adipose-derived stem cells (ADSC and mouse osteoblastic cells (MC3T3-E1 were evaluated in vitro by the MTT assay, semi-quantitative RT-PCR, and immunoblotting using cells cultured in medium supplemented with extracts from bioceramics, including calcium metaphosphate (CMP, hydroxyapatite (HA and collagen-grafted HA (HA-col. In vivo evaluation of the bone forming capacity of these bioceramics in rat models using femur defects and intramuscular implants for 12 weeks was performed. Histological analysis showed that newly formed stromal-rich tissues were observed in all the implanted regions and that the implants showed positive immunoreaction against type I collagen and alkaline phosphatase (ALP. The intramuscular implant region, in particular, showed strong positive immunoreactivity for both type I collagen and ALP, which was further confirmed by mRNA expression and immunoblotting results, indicating that each bioceramic material enhanced osteogenesis stimulation. These results support our hypothesis that smart bioceramics can induce osteoconduction and osteoinduction in vivo, although mature bone formation, including lacunae, osteocytes, and mineralization, was not prominent until 12 weeks after implantation.

  20. Growth and Photosynthetic Characteristics of Two Strawberry Cultivars in Response to Furostanol Glycosides Treatments

    Raluca Petronela CĂULEŢ


    Full Text Available Furostanol glycosides represent a large group of steroid compounds of plant origin with a broad spectrum of biological activities (anabolic, antioxidant, anti-fungal and nematicidal. Most of the research exhibits this effect in stress induced response on different pathogen attacks and only a few studies show the effect of glycoside on plants growth and development. In order to investigate the effects of furostanol glycoside treatment on rooting, growth performance and photosynthetic system efficiency, young unrooted strawberry plants (cv. ‘Real’ and ‘Magic’ were immersed in different concentrations (0.03 mM, 0.3 mM, 3 mM of G1 solution (glycoside extracted from Lycopersicon sp. and G2 (extracted from Digitalis sp. and morphometric parameters were determined. The results showed that immersion in 0.3 mM glycoside solution improved the quality of strawberry planting material by increasing the number and length of roots, as well as by stimulating formation of new leaves. Moreover, the influence of foliar spraying with G1 and G2 on plants growth, assimilator pigments content and photosynthesis was determined. Foliar spraying with both glycosides solutions improved radicular growth and development, but dimensions of foliar apparatus increased only in G1 treated variants. Although both glycoside treatments induced an increase in assimilator pigments content, photosynthetic rate decreased as a consequence of stomatal limitations associated with better efficiency of water use and of internal CO2, which suggests that these chemicals may have an antitranspirant action.

  1. Determining the dispersion characteristics of rivers from the frequency response of the system

    Lambertz, Peter; Palancar, MaríA. C.; Aragón, José M.; Gil, Roberto


    A new method of determining the parameters of an aggregated dead zone model (ADZ) to predict longitudinal dispersion in rivers is presented. The method is based on the frequency response analysis (FRA) of observed field tests, which consist of tracer injections (input) and measurement of tracer in downstream sampling points (output) located downstream from the injection point. The ADZ is a combination of plug and completely mixed flow compartments. The ADZ parameters (number of compartments, mean residence time, and delay time) are evaluated by means of Bode plots that give the system order (number of compartments), gain, time constant (mean residence time of each compartment) and delay time. The FRA-ADZ method was checked with tracer data runs in two Spanish rivers, the Tagus and the Ebro rivers. The experimental tracer concentration versus time distributions were compared with the ADZ predicted curves, which were calculated using parameters obtained from the FRA method, and with curves predicted by several classical models. The residence time of several reaches within the two studied rivers was predicted by the FRA-ADZ method with a relative error lower than 10%. The method is generally applicable to ideal and nonideal inputs and is particularly well suited to arbitrary-shaped initial source concentration distributions.

  2. Turbulent Flow Characteristics and Dynamics Response of a Vertical-Axis Spiral Rotor

    Yuli Wang


    Full Text Available The concept of a vertical-axis spiral wind rotor is proposed and implemented in the interest of adapting it to air flows from all directions and improving the rotor’s performance. A comparative study is performed between the proposed rotor and conventional Savonius rotor. Turbulent flow features near the rotor blades are simulated with Spalart-Allmaras turbulence model. The torque coefficient of the proposed rotor is satisfactory in terms of its magnitude and variation through the rotational cycle. Along the height of the rotor, distinct spatial turbulent flow patterns vary with the upstream air velocity. Subsequent experiments involving a disk generator gives an in-depth understanding of the dynamic response of the proposed rotor under different operation conditions. The optimal tip-speed ratio of the spiral rotor is 0.4–0.5, as is shown in both simulation and experiment. Under normal and relative-motion flow conditions, and within the range of upstream air velocity from 1 to 12 m/s, the output voltage of the generator was monitored and statistically analyzed. It was found that normal air velocity fluctuations lead to a non-synchronous correspondence between upstream air velocity and output voltage. In contrast, the spiral rotor’s performance when operating from the back of a moving truck was significantly different to its performance under the natural conditions.

  3. Potentiometric Response Characteristics of Membrane-Based Cs+-Selective Electrodes Containing Ionophore-Functionalized Polymeric Microspheres

    Shane Peper


    Full Text Available Cs+-selective solvent polymeric membrane-based ion-selective electrodes (ISEs were developed by doping ethylene glycol-functionalized cross-linked polystyrene microspheres (P-EG into a plasticized poly(vinyl chloride (PVC matrix containing sodium tetrakis-(3,5-bis(trifluoromethylphenyl borate (TFPB as the ion exchanger. A systematic study examining the effects of the membrane plasticizers bis(2-ethylhexyl sebacate (DOS, 2-nitrophenyl octyl ether (NPOE, and 2-fluorophenyl nitrophenyl ether (FPNPE on the potentiometric response and selectivity of the corresponding electrodes was performed. Under certain conditions, P-EG-based ion-selective electrodes (ISEs containing TFPB and plasticized with NPOE exhibited a super-Nernstian response between 1×10−3 and 1×10−4 M Cs+, a response characteristic not observed in analogous membranes plasticized with either DOS or FPNPE. Additionally, the performance of P-EG-based ISEs was compared to electrodes based on two mobile ionophores, a neutral lipophilic ethylene glycol derivative (ethylene glycol monooctadecyl ether (U-EG and a charged metallacarborane ionophore, sodium bis(dicarbollylcobaltate(III (CC. In general, P-EG-based electrodes plasticized with FPNPE yielded the best performance, with a linear range from 10-1–10-5 M Cs+, a conventional lower detection limit of 8.1×10−6 M Cs+, and a response slope of 57.7 mV/decade. The pH response of P-EG ISEs containing TFPB was evaluated for membranes plasticized with either NPOE or FPNPE. In both cases, the electrodes remained stable throughout the pH range 3–12, with only slight proton interference observed below pH 3.

  4. Impacts of temperament on Nellore cattle: physiological responses, feedlot performance, and carcass characteristics.

    Francisco, C L; Resende, F D; Benatti, J M B; Castilhos, A M; Cooke, R F; Jorge, A M


    concentration compared with ADQ cattle. Both temperament groups had similar serum concentrations of IgA ( = 0.25) and total protein ( = 0.84). Cattle classified as EXC presented greater amounts ( = 0.05) of carcass bruises. In conclusion, an EXC temperament impaired feedlot performance, carcass characteristics, and meat quality traits in finishing Nellore cattle.

  5. Effects of User and System Characteristics on Perceived Usefulness and Perceived Ease of Use of the Web-Based Classroom Response System

    Ke, Chih-Horng; Sun, Huey-Min; Yang, Yuan-Chi; Sun, Huey-Min


    This study explores the effect of user and system characteristics on our proposed web-based classroom response system (CRS) by a longitudinal design. The results of research are expected to understand the important factors of user and system characteristics in the web-based CRS. The proposed system can supply interactive teaching contents,…

  6. Clinical characteristics and therapeutic response in patients with Burning Mouth Syndrome: accompanying 2 years

    Vanessa Juliana Gomes CARVALHO

    Full Text Available Abstract Introduction Burning Mouth Syndrome (BMS is a condition characterized by burning symptom of the oral mucosa in the absence of clinical signs. Its etiology is still unknown and, and to date there is no effective treatment. Purpose The aim of this study was to evaluate patients with BMS profile and the therapies results in a retrospective study. Material and method Clinical and therapeutic data were collected from records of patients with BMS diagnosed between January 2013 to April 2015 at the Clinic of Stomatology Clinic, Faculdade de Odontologia of Universidade de São Paulo, according to the criteria established by the International Headache Society in 2013. The therapies used for BMS control were also evaluated. Result Twelve patients were diagnosed with BMS at this period. All of them were women with a mean age of 61.18 years and the apex of the tongue was the most common affected site and the duration of the burning sensation ranged from 6 months to 25 years. Many therapies were prescribed for BMS control, such as topical capsaicin, topical clonazepan, low level laser therapy and homeopathy. Among the established therapies, capsaicin has immediate effect in reducing symptoms. Conclusion The present study showed that the challenges towards an effective treatment for BMS are varied and are mainly related to the lack knowing of the pathogenesis of this disease. The demographic profile of patients studied here was similar to that described in the available literature, however, the variables represented by secondary symptoms (medical history, anxiety and depression levels may be modifying factors of therapeutic response and the pathogenesis of the disease itself.

  7. Endoscopic characteristics and levodopa responsiveness of swallowing function in progressive supranuclear palsy.

    Warnecke, Tobias; Oelenberg, Stephan; Teismann, Inga; Hamacher, Christina; Lohmann, Hubertus; Ringelstein, Erich Bernd; Dziewas, Rainer


    Dysphagia is a frequent and early symptom in progressive supranuclear palsy (PSP) predisposing patients to aspiration pneumonia. Fiberoptic endoscopic evaluation of swallowing (FEES) has emerged as a valuable apparative tool for objective evaluation of neurogenic dysphagia. This is the first study using FEES to investigate the nature of swallowing impairment in PSP. Eighteen consecutive PSP patients (mean age 69.7 +/- 9.0 years) were included. The salient findings of FEES in PSP patients were compared with those of 15 patients with Parkinson's disease (PD). In 7 PSP patients, a standardized FEES protocol was performed to explore levodopa (L-dopa) responsiveness of dysphagia. Most frequent abnormalities detected by FEES were bolus leakage, delayed swallowing reflex, and residues in valleculae and piriformes. Aspiration events with at least one food consistency occurred in nearly 30% of PSP patients. Significant pharyngeal saliva pooling was observed in 4 PSP patients. We found no difference of salient endoscopic findings between PSP and PD patients. Endoscopic dysphagia severity in PSP correlated positively with disease duration, clinical disability, and cognitive impairment. No correlation was found with dysarthria severity. In early PSP patients, swallowing dysfunction was solely characterized by liquid leakage with the risk of predeglutitive aspiration during the oral phase of swallowing. Two PSP patients showed relevant improvement of swallowing function after L-dopa challenge. Chin tuck-maneuver, hard swallow, and modification of food consistency were identified as the most effective therapeutic interventions. In conclusion, FEES assessment can deliver important findings for the diagnosis and refined therapy of dysphagia in PSP patients.

  8. Regeneration Responses to Management for Old-Growth Characteristics in Northern Hardwood-Conifer Forests

    Aviva J. Gottesman


    Full Text Available Successful tree regeneration is essential for sustainable forest management, yet it can be limited by the interaction of harvesting effects and multiple ecological drivers. In northern hardwood forests, for example, there is uncertainty whether low-intensity selection harvesting techniques will result in adequate and desirable regeneration. Our research is part of a long-term study that tests the hypothesis that a silvicultural approach called “structural complexity enhancement” (SCE can accelerate the development of late-successional forest structure and functions. Our objective is to understand the regeneration dynamics following three uneven-aged forestry treatments with high levels of retention: single-tree selection, group selection, and SCE. Regeneration density and diversity can be limited by differing treatment effects on or interactions among light availability, competitive environment, substrate, and herbivory. To explore these relationships, manipulations and controls were replicated across 2 ha treatment units at two Vermont sites. Forest inventory data were collected pre-harvest and periodically over 13 years post-harvest. We used mixed effects models with repeated measures to evaluate the effect of treatment on seedling and sapling density and diversity (Shannon–Weiner H’. The treatments were all successful in recruiting a sapling class with significantly greater sapling densities compared to the controls. However, undesirable and prolific beech (Fagus americana sprouting dominates some patches in the understory of all the treatments, creating a high degree of spatial variability in the competitive environment for regeneration. Multivariate analyses suggest that while treatment had a dominant effect, other factors were influential in driving regeneration responses. These results indicate variants of uneven-aged systems that retain or enhance elements of stand structural complexity—including old-growth characteristics

  9. Polysaccharides As Viscosupplementation Agents: Structural Molecular Characteristics but Not Rheology Appear Crucial to the Therapeutic Response

    Rita C. Machado


    Full Text Available IntroductionMost clinical studies and basic research document viscosupplementation (VS in terms of effectiveness and safety, but only a few highlight its molecular mechanisms of action. Besides, there is generally focus on hyaluronic acid (HA as being the most relevant polysaccharide to reach the clinical endpoints, attributing its effect mainly to its unique viscoelastic properties, related to a high-molecular weight and gel formulation. Usually, studies do not approach the possible biological pathways where HA may interfere, and there is a lack of reports on other biocompatible polysaccharides that could be of use in VS.AimWe briefly review the main proposed mechanisms of action of intra-articular hyaluronic acid (IA-HA treatment and discuss its effectiveness focusing on the role of rheological and intrinsic structural molecular properties of polysaccharides in providing a therapeutic effect.MethodsWe conducted a literature search using PubMed database to find articles dealing with the mechanisms of action of IA-HA treatment and/or emphasizing how the structural properties of the polysaccharide used influenced the clinical outcomes.Discussion/conclusionHA is involved in numerous biochemical interactions that may explain the clinical benefits of VS, most of them resulting from HA–cluster of differentiation 44 receptor interaction. There are other important aspects apart from the molecular size or the colloidal state of the IA-HA involved in VS efficiency that still need to be consolidated. Indeed, it seems that clinical response may be dependent on the intrinsic properties of the polysaccharide, regardless of being HA, rather than to rheology, posing some controversy to previous beliefs.

  10. Studies on Decolorization Characteristics of Crude Peroxidase from Raphanus sativus Using Response Surface Methodology

    Poornima RAMAMOORTHI


    Full Text Available Dye decolorization with the help of a plant based enzyme was investigated. Crude peroxidase (35.58 U/ml extracted from the pulp of Raphanus sativus (radish was used for decolorization of a basic dye, safranin. The effect of the influencing parameters of pH, temperature, dye concentration, and enzyme concentration on safranin decolorization was primarily studied using the traditional One Factor At a Time method (OFAT. The optimal values of each influencing parameter for maximum decolorization were obtained via the OFAT approach which can be extended to study factorial interactions by applying range levels statistically. To obtain the optimal operating conditions for decolorization, the influencing process parameters were optimized further by applying Response Surface Methodology based on Box-Behnken Design. A three level four factor design was generated using the Design Expert software version A quadratic model was fitted for the experimental data obtained, and the significance of the model predicted was analyzed through Analysis of Variance (ANOVA at the 95 % confidence interval. The determination coefficient, R², of the model was found to be 0.8993. The optimal process conditions were found to be a temperature of 30 °C, a dye concentration of 200 mg/l, an incubation time of 60 min, and an enzyme concentration of 26.69 U/ml, producing 30.07 % decolorization at an optimum pH of 7, which is in accordance with the predicted value of 29.24 %. Confirmatory experiments verified the adequacy of the model. The study provides a foundation for further research on enzyme based decolourization of safranin.

  11. Triple X syndrome: characteristics of 42 Italian girls and parental emotional response to prenatal diagnosis.

    Lalatta, Faustina; Quagliarini, Donatella; Folliero, Emanuela; Cavallari, Ugo; Gentilin, Barbara; Castorina, Pierangela; Forzano, Francesca; Forzano, Serena; Grosso, Enrico; Viassolo, Valeria; Naretto, Valeria Giorgia; Gattone, Stefania; Ceriani, Florinda; Faravelli, Francesca; Gargantini, Luigi


    We report clinical and behavioural evaluation data in 42 Italian girls with triple X syndrome whose diagnosis was made prenatally between 1998 and 2006 in three Italian centres. At initial evaluation, reproductive and medical histories were collected. Clinical assessment of the child was performed by a clinical geneticist and included a detailed personal history, physical evaluation and auxological measurements. To analyse how parents coped with specific events in the prenatal and postnatal periods, we conducted an interview that included 35 specific questions designed to elicit retrospective judgements on prenatal communication, present and future worries, needs and expectations. In a subset of probands, we also administered the formal Italian Temperament Questionnaire assessment test that investigates adaptation, general environment and socialisation. This test also assesses the emotional component of temperament. Clinical results in the affected children are similar to those previously reported with evidence of increased growth in the pre-puberal age and an average incidence of congenital malformation and health needs. Median age for the time first words were pronounced was 12 months, showing a slight delay in language skills, which tended to improve by the time they reached school age. Parental responses to the interview demonstrated residual anxiety but with a satisfactory adaptation to and a positive recall of the prenatal counselling session. Parental adaptation of the 47,XXX girls require indeed a proper educational support. This support seems to be available in Italy. An integrated approach to prenatal counselling is the best way to manage the anxiety and falsely imagined consequences that parents feel after being told that their foetus bears such a genetic abnormality.

  12. Response monitoring and action limits: use of ADC numbers in understanding the operational characteristics of the Beckman ASTRA chemistry system.

    Kessner, A; Burnett, R W; Bowers, G N


    The Beckman ASTRA is a microprocessor-controlled multichannel chemistry analyzer. The output of each module is available to the operator as analog-to-digital conversion (ADC) numbers, which we record during each calibration (Response Monitoring). After so studying three instruments for a total of 33 months, we have established limits for Calibrator ADC numbers that indicate possible operator action (Action Limits). These Action Limits are tighter than the microprocessor's programmed limits, and alert the operator to short- and long-term drift. These tighter limits warn of (a) impending failure of the instrument to calibrate or (b) possible inaccuracies in results for patients. We have instituted changes in preventive maintenance based on our studies of each module's operational characteristics, and have replaced electrodes that failed to meet our Response Monitoring specifications. Response Monitoring and Action Limits based upon ADC numbers have significantly enhanced our understanding of the ASTRA system and thus improved its operational efficiency and analytical reliability. Estimates of precision and accuracy (true value) were satisfactory in comparison to our prior single-channel continuous-flow and flame photometry analytical measurement systems.

  13. Study on the dose response characteristics of a scanning liquid ion-chamber electronic portal imaging device

    Ma Shao Gang; Song Yi Xin


    Objective: To study the dose response characteristics and the influence factors such as gantry angle, field size and acquisition mode on the dosimetric response curves, when using a scanning liquid ion-chamber electronic portal imaging device (EPID) for dose verification. Methods: All experiments were carried out on a Varian 600 C/D accelerator (6 MV X-ray) equipped with a Varian PortalVision sup T sup M MK2 type EPID. To obtain the dose response curve, the relationship between the incident radiation intensity to the detector and the pixel value output from the EPID were established. Firstly, the different dose rates of 6 MV X-rays were obtained by varying SSD. Secondly, three digital portal images were acquired for each dose rate using the EPID and averaged to avoid the influence of the dose rate fluctuations of the accelerator. The pixel values of all images were read using self-designed image analysis software, and and average for a region consisting of 11 x 11 pixels around the center was taken as the res...

  14. Establishing Chinese medicine characteristic tumor response evaluation system is the key to promote internationalization of Chinese medicine oncology.

    Li, Jie; Li, Lei; Liu, Rui; Lin, Hong-sheng


    The features and advantages of Chinese medicine (CM) in cancer comprehensive treatment have been in the spotlight of experts both at home and abroad. However, how to evaluate the effect of CM more objectively, scientifically and systematically is still the key problem of clinical trial, and also a limitation to the development and internationalization of CM oncology. The change of tumor response evaluation system in conventional medicine is gradually consistent with the features of CM clinical effect, such as they both focus on a combination of soft endpoints (i.e. quality of life, clinical benefit, etc.) and hard endpoints (i.e. tumor remission rate, time to progress, etc.). Although experts have proposed protocols of CM tumor response evaluation criteria and come to an agreement in general, divergences still exist in the importance, quantification and CM feature of the potential endpoints. Thus, establishing a CM characteristic and wildly accepted tumor response evaluation system is the key to promote internationalization of CM oncology, and also provides a more convenient and scientific platform for CM international cooperation and communication.

  15. High-strain-rate tensile mechanical response of a polyurethane elastomeric material

    Fan, J.T.; Weerheijm, J.; Sluys, L.J.


    The dynamic tensile mechanical response of a soft polymer material (Clear Flex 75) is investigated using a split Hopkinson tension bar (SHTB). Stress-strain relations are derived to reveal the mechanical properties at moderate and high strain rates. These relations appear to be rate dependent. Under

  16. Optimized balance rehabilitation training strategy for the elderly through an evaluation of balance characteristics in response to dynamic motions

    Jung HH


    Full Text Available HoHyun Jung,1 Keyoung Jin Chun,2 Jaesoo Hong,2 Dohyung Lim1 1Department of Mechanical Engineering, Sejong University, Seoul, Republic of Korea; 2Smart Welfare Technology Research Group, Korea Institute of Industrial Technology, Cheonan, Republic of Korea Abstract: Balance is important in daily activities and essential for maintaining an independent lifestyle in the elderly. Recent studies have shown that balance rehabilitation training can improve the balance ability of the elderly, and diverse balance rehabilitation training equipment has been developed. However, there has been little research into optimized strategies for balance rehabilitation training. To provide an optimized strategy, we analyzed the balance characteristics of participants in response to the rotation of a base plate on multiple axes. Seven male adults with no musculoskeletal or nervous system-related diseases (age: 25.5±1.7 years; height: 173.9±6.4 cm; body mass: 71.3±6.5 kg; body mass index: 23.6±2.4 kg/m2 were selected to investigate the balance rehabilitation training using customized rehabilitation equipment. Rotation of the base plate of the equipment was controlled to induce dynamic rotation of participants in the anterior–posterior, right-diagonal, medial–lateral, and left-diagonal directions. We used a three-dimensional motion capture system employing infrared cameras and the Pedar Flexible Insoles System to characterize the major lower-extremity joint angles, center of body mass, and center of pressure. We found statistically significant differences between the changes in joint angles in the lower extremities in response to dynamic rotation of the participants (P<0.05. The maximum was greater with anterior–posterior and medial–lateral dynamic rotation than with that in other directions (P<0.05. However, there were no statistically significant differences in the frequency of center of body mass deviations from the base of support (P>0.05. These results

  17. Optical response and magnetic characteristic of samarium doped zinc phosphate glasses containing nickel nanoparticles

    Azmi, Siti Amlah M.; Sahar, M.R., E-mail:


    A magnetic glass of composition 40ZnO–(58−x) P{sub 2}O{sub 5}–1Sm{sub 2}O{sub 3}–xNiO, with x=0.0, 1.0, 1.5 and 2.0 mol% is prepared by melt-quenching technique. The glass is characterized by X-ray diffraction, high-resolution transmission electron microscope (HRTEM), photoluminescence (PL) spectroscopy and vibrating sample magnetometer (VSM) analysis. The X-rays diffraction confirms the amorphous nature of the glass while the HRTEM analysis reveals the presence of nickel nanoparticles in the glass samples. High-resolution TEM reveals that the lattice spacing of nickel nanoparticles is 0.35 nm at (100) plane. Photoluminescence emission shows the existence of four peaks that correspond to the transition from the upper level of {sup 4}G{sub 5/2} to the lower level of {sup 6}H{sub 5/2}, {sup 6}H{sub 7/2}, {sup 6}H{sub 9/2,} and {sup 6}H{sub 11/2.} It is observed that all peaks experience significant quenching effect with the increasing concentration of nickel nanoparticles, suggesting a strong energy transfer from excited samarium ions to the nickel ions. The glass magnetization and susceptibility at 12 kOe at room temperature are found to be in the range of (3.87±0.17×10{sup −2}–7.19±0.39×10{sup −2}) emu/g and (3.24±0.16×10{sup −6}–5.99±0.29×10{sup −6}) emu/Oe g respectively. The obtained hysteresis curve indicates that the glass samples are paramagnetic materials. The studied glass can be further used towards the development of magneto-optical functional glass. - Highlights: • Sm{sup 3+} doped zinc phosphate glass embedded with Ni NPs has been prepared. • The Laue pattern and lattice spacing of Ni NPs are confirmed by HRTEM image. • The magnetic response of glasses has been studied through VSM analysis. • Enhancement factor and decay half-lifetime are investigated.

  18. Intensive care unit admission in patients following rapid response team activation: call factors, patient characteristics and hospital outcomes.

    Le Guen, M P; Tobin, A E; Reid, D


    Rapid Response Systems (RRSs) have been widely introduced throughout hospital health systems, yet there is limited research on the characteristics and outcomes of patients admitted to an intensive care unit (ICU) following RRS activation. Using database extraction, this study examined the factors associated with ICU admission and patient outcome in patients receiving RRS activation in a tertiary level hospital between 2009 and 2013. Of 3004 RRS activations, 392 resulted in ICU admissions. Call factors associated with ICU admission and increased hospital mortality included tachypnoea (P Medical Emergency Team call triggers breached simultaneously (P admission included young age (P admission and hospital mortality post RRS activation. This information may be useful for risk stratification of deteriorating patients and determination of appropriate escalation.

  19. Effects of Control-Response Characteristics on the Capability of Helicopter for Use as a Gun Platform

    Pegg, Robert J.; Connor, Andrew B.


    An investigation with a variable-stability helicopter was undertaken to ascertain the steadiness and ability to "hold on" to the target of a helicopter employed as a gun platform. Simulated tasks were per formed under differing flight conditions with the control-response characteristics of the helicopter varied for each task. The simulated gun-platform mission included: Variations of headings with respect to wind, constant altitude and "swing around" to a wind heading of 0 deg, and increases in altitude while performing a swing around to a wind heading of 0 deg. The results showed that increases in control power and damping increased pilot ability to hold on to the target with fewer yawing oscillations and in a shorter time. The results also indicated that wind direction must be considered in accuracy assessment. Greatest accuracy throughout these tests was achieved by aiming upwind.

  20. Dynamic response characteristics of high temperature superconducting maglev systems: Comparison between Halbach-type and normal permanent magnet guideways

    Wang, B. [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); Zheng, J., E-mail: [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); Che, T. [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); Zheng, B.T.; Si, S.S. [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China); School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, P R China (China); Deng, Z.G., E-mail: [Applied Superconductivity Laboratory, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, P R China (China)


    Highlights: • The loading weight affects the RF tremendously. • Reducing the FCH can improve the stability of the maglev vehicle. • The Halbach-type PMG has better loading capacity than the conventional PMG. • Pre-load is an effective way to enhance the dynamic characteristic of the HTS maglev vehicle. - Abstract: The permanent magnet guideway (PMG) is very important for the performance of the high temperature superconducting (HTS) system in terms of electromagnetic force and operational stability. The dynamic response characteristics of a HTS maglev model levitating on two types of PMG, which are the normal PMG with iron flux concentration and Halbach-type PMG, were investigated by experiments. The dynamic signals for different field-cooling heights (FCHs) and loading/unloading processes were acquired and analyzed by a vibration analyzer and laser displacement sensors. The resonant frequency, stiffness and levitation height of the model were discussed. It was found that the maglev model on the Halbach-type PMG has higher resonant frequency and higher vertical stiffness compared with the normal PMG. However, the low lateral stiffness of the model on the Halbach-type PMG indicates poor lateral stability. Besides, the Halbach-type PMG has better loading capacity than the normal PMG. These results are helpful to design a suitable PMG for the HTS system in practical applications.

  1. Stress-strain relationship of granular materials based on two cell systems%基于双胞元的颗粒材料应力-应变关系研究

    董启朋; 姚海林; 卢正; 詹永祥


    基于细观力学,建立颗粒材料的宏观应力-应变与接触力、接触位移、枝矢量等细观量之间的关系。用改进的Voronoi-Delaunay法对颗粒材料进行几何和物理上划分,得到改进Bagi双胞元体系;以固体胞元为基础,运用牛顿第二定律和Gauss定理提出含有旋转矢量和重力的颗粒材料平均等效应力,避免了颗粒材料的准静态假设;在孔隙胞元区域内利用变形协调条件推导出含有孔隙面矢量等几何变量的颗粒材料平均等效应变。结合文献的二维颗粒材料宏观试验结果验证了双胞元平均等效应力-应变的正确性;在三维情形下,对比双胞元等效应变和最优拟合应变结果,同样验证了基于双胞元的颗粒材料应力-应变关系,因此,该颗粒材料应力-应变关系可以为数值模拟颗粒材料力学行为提供依据。%Based on granular mesomechanics, this paper sets up the relationship between the macro stress-strain and the mesoscopic quantities including the contact force, contact displacement and branch vector in granular materials. The method of improved Voronoi-Delaunay tessellation for granular materials in geometry and physics is further modified into two cell systems of Bagi. Taking solid cell systems as the basic elements, the average stress tensor that includes particle rotation vector and acceleration of gravity is derived based on Newton’s second law of motion and Gauss theorem. It avoids a static hypothesis. The average strain tensor expression including the void surface vector is derived based on the void cell with compatibility requirement. Two cell systems average equivalent stress-strain is correct combined with the literature of experimental resulting in two dimensions. Compared with two cell systems average equivalent strain and best fitting stress results under three dimensions, granular material stress-strain relationship based on the two cell systems is also

  2. The pathways responsible for the characteristic head posture produced by lesions of the interstitial nucleus of Cajal in the cat.

    Fukushima, K; Fukushima, J; Terashima, T


    (1) Experiments were performed in cats to examine effects of lesion of the interstitial nucleus of Cajal (INC) on head posture and the responsible pathway. Unilateral INC lesions resulted in lateral tilt of the head to the opposite side, and bilateral INC lesions resulted in dorsiflexion of the head as reported earlier. Such characteristic head posture was produced by successful kainic acid injections as well as by electrolytic lesions, suggesting that it was not due to damage of nerve fibers passing through the INC, but was produced most probably by damage of nerve cells in the INC. Electromyographic (EMG) recordings in unilateral INC-lesioned cats showed that activity was higher in the ipsilateral than in the contralateral major dorsal neck muscles (biventer, splenius, complexus, and rectus), and also higher in the contralateral than in the ipsilateral obliquus capitis caudalis muscle. The pattern of EMG activity was basically similar either when the cats presented typical head tilt or when their head was fixed to the frame at the stereotaxic plane. Characteristic head posture resulting from INC lesions seems consistent with the head posture produced by activation of these muscles. (2) Interruption of the medial and lateral vestibulospinal tracts did not significantly influence head tilt that had been produced by INC lesions. Characteristic head tilt was produced by INC lesions after cats had received bilateral labyrinthectomies, bilateral lesions of most of the vestibular nuclei, and bilateral aspiration of the cerebellar vermis and most of the lateral vestibular nuclei, indicating that typical head tilt can be produced without the vestibular nuclei and cerebellar vermis. (3) The medial longitudinal fasciculus (MLF) was interrupted at different levels to cut the major descending fibers from the INC. MLF interruption at the caudal midbrain produced typical head tilt, although MLF cut at the caudal pons and medulla was ineffective. Bilateral parasagittal cuts

  3. Experimental study of stress-strain state of adhesive joints steel / carbon fiber under tension with a bend by digital image correlation

    Kopanitsa, D. G.; Ustinov, A. M.; Kondratyuk, A. A.; Abzaev, Y. A.; Potekaev, A. I.; Klopotov, A. A.; Kopanitsa, G. D.


    This paper presents a study of characteristics of an evolution of deformation fields in surface layers of medium-carbon low-alloy specimens under compression. The experiments were performed on the “Universal Testing Machine 4500” using a digital stereoscopic image processing system Vic-3D. A transition between stages is reflected as deformation redistribution on the near-surface layers.

  4. 基于实际应力-应变曲线的电沉积镍涂层的冲压成形极限%Forming Limit of Electrodeposited Nickel Coating Based on Actual Stress-strain Curves

    周里群; 邓晶; 周凯; 李玉平


    Hill localized instability theory was used to derive the stress-strain equations of nickel coating sheet during forming process.By using polynomial fitting for experimental data,actual stress-strain curves of the electrodeposited nickel coating sheet were obtained.The forming limit left region of the nickel coating sheet was calculated by solving a nonlinear equation,and compared with one by using strain hardening curves.The research results show that the forming limit of the nickel coating by polynomial fitting is higher in security than the one by strain hardening curves,and the substrate anisotropy,coating thickness and substrate thickness have little influences on the formed limit curves.The results may play a directive role on the electrodeposited nickel coating sheet preparation.%基于Hill集中失稳理论推导出了冲压成形过程中涂层与基体的应力-应变方程,通过求解非线性方程计算出各主应变。依据实验数据采用多项式拟合法拟合了材料的应力-应变曲线,对电沉积镍涂层的冲压成形极限的左边进行了计算,并和应变硬化曲线求得的成形极限进行了比较。计算结果表明,用多项式拟合法求得的电沉积镍涂层的成形极限安全区域比用应变硬化曲线求得的安全区域要高,基体厚向异性、涂层厚度和基体厚度对板料成形极限左边影响不大。

  5. Investigation of the response characteristics of OSL albedo neutron dosimeters in a 241AmBe reference neutron field

    Liamsuwan, T.; Wonglee, S.; Channuie, J.; Esoa, J.; Monthonwattana, S.


    The objective of this work was to systematically investigate the response characteristics of optically stimulated luminescence Albedo neutron (OSLN) dosimeters to ensure reliable personal dosimetry service provided by Thailand Institute of Nuclear Technology (TINT). Several batches of InLight® OSLN dosimeters were irradiated in a reference neutron field generated by the in-house 241AmBe neutron irradiator. The OSL signals were typically measured 24 hours after irradiation using the InLight® Auto 200 Reader. Based on known values of delivered neutron dose equivalent, the reading correction factor to be used by the reader was evaluated. Subsequently, batch homogeneity, dose linearity, lower limit of detection and fading of the OSLN dosimeters were examined. Batch homogeneity was evaluated to be 0.12 ± 0.05. The neutron dose response exhibited a linear relationship (R2=0.9974) within the detectable neutron dose equivalent range under test (0.4-3 mSv). For this neutron field, the lower limit of detection was between 0.2 and 0.4 mSv. Over different post-irradiation storage times of up to 180 days, the readings fluctuated within ±5%. Personal dosimetry based on the investigated OSLN dosimeter is considered to be reliable under similar neutron exposure conditions, i.e. similar neutron energy spectra and dose equivalent values.

  6. Metabolic characteristics of muscles in the spiny lobster, Jasus edwardsii, and responses to emersion during simulated live transport.

    Speed, S R; Baldwin, J; Wong, R J; Wells, R M


    The metabolic characteristics of five muscle groups in the spiny lobster Jasus edwardsii were examined in order to compare their anaerobic and oxidative capacities. Enzyme activities of phosphorylase, phosphofructokinase, pyruvate kinase, and lactate dehydrogenase were highest in abdominal muscles supporting anaerobic burst activity. Hexokinase, citrate synthase, and HOAD activities in the leg and antennal muscles indicated higher aerobic potential. Arginine kinase activities were high in all muscle groups indicating that muscle phosphagens are an important energy reserve. Arginine phosphate concentrations in 4th periopod and abdominal flexor muscle from lobsters sampled in the field were higher than any values from captive animals, and approximately five times those for ATP. Muscle lactates were high in captive animals. Responses to emersion during simulated live transport appear to exploit the capacity for functional anaerobiosis and further differentiated the muscle groups. Abdominal muscles were especially sensitive and after 24 h showed significant increases in lactate, glucose, ADP, and AMP. ATP levels appeared to be maintained by muscle phosphagens and raised doubts about the efficacy of the adenylate energy charge in evaluating the emersion response. Haemolymph glucose, lactic acid, and ammonia peaked after 24 h emersion and were largely restored following re-immersion. We propose that arginine phosphate concentrations in the 4th periopod are an appropriate index of metabolic stress, and could lead to improved commercial handling protocols.

  7. Realtime Prediction in Disturbed Landscapes: Identifying Highest Priority Disturbance Characteristics Impacting Streamflow Response in a CONUS-Scale Operational Model

    Dugger, A. L.; Gochis, D. J.; Yu, W.; McCreight, J. L.; Barlage, M. J.


    The "next generation" of hydrologic prediction systems - targeting unified, process-based, real-time prediction of the total water cycle - bring with them an increased need for real-time land surface characterization. Climatologically-derived estimates may perform well under stationary conditions, however disturbance can significantly alter hydrologic behavior and may be poorly represented by mean historical conditions. Fortunately, remote sensing and on-the-ground observation networks are collecting snapshots of these land characteristics over an increasing fraction of the globe. Given the computing constraints of operating a large-domain, real-time prediction system, to take advantage of these data streams we need a way to prioritize which landscape characteristics are most important to hydrologic prediction post-disturbance. To address this need, we setup a model experiment over the contiguous US using the community WRF-Hydro system with the NoahMP land surface model to assess the value of incorporating various aspects of disturbed landscapes into a real-time streamflow prediction model. WRF-Hydro will serve as the initial operational model for the US National Weather Service's new national water prediction effort, so use of WRF-Hydro allows us to leverage both an existing CONUS-scale model implementation and a short research-to-operations path. We first identify USGS GAGES-II basins that experienced more than 25% forest loss between 2000 and 2013. Based on basin disturbance type, geophysical setting, and climate regime, we formulate a conceptual model of which "disturbed" landscape characteristics we expect to dominate streamflow response. We test our conceptual model using WRF-Hydro by modeling a baseline (no disturbance) case, and then bringing in empirically-derived model state shifts representing key disturbance characteristics (e.g., leaf area index, rooting depth, overland roughness, surface detention). For each state update and each basin, we quantify

  8. Experimental aspects of stress-strain curves determination at high temperature and controlled atmosphere: Al{sub 2}O{sub 3}-MgO-C refractories; Aspectos experimentales de la determinacion de curvas esfuerzo-deformacion a alta temperatura y en atmosfera controlada: Refractarios Al{sub 2}O{sub 3}-MgO-C

    Munoz, V.; Rohr, G. A.; Tomba Martinez, A. G.; Cavalieri, A. L.


    A methodology for the mechanical evaluation of refractory materials at high temperatures and controlled atmosphere, designed and implemented in the Structural Materials Laboratory of Ceramics Division of INTEMA, is described. The methodology includes the measurement of the specimen deformation by contact extensometry in compression tests to obtain stress-strain curves and the use of a gaseous flow as a system to control atmosphere. The determination of stress-strain curves of Al{sub 2}O{sub 3}-MgO-C commercial refractories used in steelmaking ladles at room temperature and 1260 degree centigrade in different atmospheres is presented as an example of application of this methodology. (Author) 34 refs.

  9. Application of a characteristic periods-based (CPB) approach to estimate earthquake-induced displacements of landslides through dynamic numerical modelling

    Martino, S.; Lenti, L.; Delgado, J.; Garrido, J.; Lopez-Casado, C.


    The interaction between seismic waves and slopes is an important topic to provide reliable scenarios for earthquake-(re)triggered landslides. The physical properties of seismic waves as well as slope topography and geology can significantly modify the local seismic response, influencing landslide triggering. A novel approach is here applied to two case studies in Andalusia (southern Spain) for computing the expected earthquake-induced displacements of existing landslide masses. Towards this aim, dynamic stress-strain numerical modelling was carried out using a selection of seismic signals characterized by different spectral content and energy. In situ geophysical measurements, consisting of noise records and temporary seismometric arrays, were carried out to control the numerical outputs in terms of local seismic response. The results consist of relationships between the characteristic period, Tm, of the seismic signals and the characteristic periods of the landslide masses, related to the thickness (Ts) and length (Tl), respectively. These relationships show that the larger the horizontal dimension (i.e. length of landslide) of a landslide is, the more effective the contribution (to the resulting coseismic displacement) of the long-period seismic waves is, as the maximum displacements are expected for a low Tm at each energy level of the input. On the other hand, when the local seismic response mainly depends on stratigraphy (i.e. landslide thickness), the maximum expected displacements occur close to the resonance period of the landslide, except for high-energy seismic inputs.

  10. Stress-strain behaviour analysis of Middle Polish glacial tills from Warsaw (Poland) based on the interpretation of advanced field and laboratory tests

    Bąkowska, Anna; Dobak, Dobak; Gawriuczenkow, Ireneusz; Kiełbasiński, Kamil; Szczepański, Tomasz; Trzciński, Jerzy; Wójcik, Emilia; Zawrzykraj, Piotr


    The selected parameters of the Wartanian and Odranian tills, with relation to their spatial occurrence, grain size distribution, mineralogical composition, matric suction and other physical characteristics, are presented. The assessment of the lithogenesis and stress history on the microstructure is attempted. The comparison of the compression and permeability characteristics from field and laboratory tests has been performed. Laboratory consolidation tests carried out with up to 20MPa vertical stress, revealed two yield stress values, one in the range of a couple hundreds kPa, the other in the range of a couple thousands kPa. Based on those results, the reliability of the soil preconsolidation assessment, with the use of the two different methods is discussed. The aspect of the triaxial strength reduction under the dynamic loading of diverse frequency and amplitude is raised. The research results depict a variety of possible geological-engineering characteristics, under the divergent constraints scenarios, of compression or strength weakening origin. The effects of the specialized research program will widen the possibilities of physio-mechanical and structural characterization of soils for geological-engineering purposes.

  11. Types of adult attention-deficit hyperactivity disorder (ADHD): baseline characteristics, initial response, and long-term response to treatment with methylphenidate.

    Reimherr, Fred W; Marchant, Barrie K; Gift, Thomas E; Steans, Tammy A; Wender, Paul H


    Much recent research describes the importance of emotional symptoms in ADHD. While there is no accepted system for including emotionality in diagnosing ADHD, the Wender-Reimherr Adult Attention Deficit Disorder Scale (WRAADDS) provides a tool to facilitate this. It assesses a range of adult ADHD symptoms which load on two factors: inattentive and emotional dysregulation. The consistently high inattentive factor was used to define significant elevation on the more variable emotional dysregulation factor (which contains four WRAADDS domains: hyperactivity/restlessness, temper, affective lability, and emotional over-reactivity) allowing the definition of two ADHD diagnostic types. We compared these two types on a broad range of adult subject characteristics, including response to methylphenidate (MPH) treatment assessed during two clinical trials. Marked impairment in three of the four emotional domains reflected a symptom severity level equivalent to that of the inattentive factor. 59 % met this threshold, defining them as ADHD emotion dysregulation presentation, as opposed to 41 % with ADHD inattentive presentation. Cluster analysis validated these groups by generating similar clusters with 85 % agreement regarding membership. ADHD emotional dysregulation presentation subjects showed more childhood ADHD symptoms, adult symptoms of oppositional defiant disorder, and evidence of personality disorder. Both types showed similar improvement during the double-blind MPH arm of the trials and during a 6-month open-label phase. Based on the presence of symptoms of emotional dysregulation, ADHD in adults can be conceptualized as two types. Impairment and comorbidity in adults with ADHD are largely concentrated in ADHD emotional dysregulation presentation patients.

  12. Linear and nonlinear characteristics of the runoff response to regional climate factors in the Qira River basin, Xinjiang, Northwest China.

    Xue, Jie; Gui, Dongwei


    The inland river watersheds of arid Northwest China represent an example of how, in recent times, climatic warming has increased the complexity of Earth's hydrological processes. In the present study, the linear and nonlinear characteristics of the runoff response to temperature and precipitation were investigated in the Qira River basin, located on the northern slope of the Kunlun Mountains. The results showed that average temperature on annual and seasonal scales has displayed a significantly increasing trend, but this has not been reflected in accumulated precipitation and runoff. Using path analysis, a positive link between precipitation and runoff was found both annually and in the summer season. Conversely, it was found that the impact of temperature on runoff has been negative since the 1960s, attributable to higher evaporation and infiltration in the Qira River basin. Over the past 50 years, abrupt changes in annual temperature, precipitation and runoff occurred in 1997, 1987 and 1995, respectively. Combined with analysis using the correlation dimension method, it was found that the temperature, precipitation and runoff, both annually and seasonally, possessed chaotic dynamic characteristics, implying that complex hydro-climatic processes must be introduced into other variables within models to describe the dynamics. In addition, as determined via rescaled range analysis, a consistent annual and seasonal decreasing trend in runoff under increasing temperature and precipitation conditions in the future should be taken into account. This work may provide a theoretical perspective that can be applied to the proper use and management of oasis water resources in the lower reaches of river basins like that of the Qira River.

  13. pH- and thermo-responsive microcontainers as potential drug delivery systems: Morphological characteristic, release and cytotoxicity studies

    Efthimiadou, Eleni K., E-mail: [Sol–Gel Laboratory, Institute for Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, NCSR “Demokritos”, 15 341 Aghia Paraskevi Attikis (Greece); Tapeinos, Christos [Sol–Gel Laboratory, Institute for Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, NCSR “Demokritos”, 15 341 Aghia Paraskevi Attikis (Greece); Materials Science Department, School of Natural Sciences, University of Patras, 26 500 Patras (Greece); Tziveleka, Leto-Aikaterini; Boukos, Nikos [Sol–Gel Laboratory, Institute for Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, NCSR “Demokritos”, 15 341 Aghia Paraskevi Attikis (Greece); Kordas, George, E-mail: [Sol–Gel Laboratory, Institute for Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, NCSR “Demokritos”, 15 341 Aghia Paraskevi Attikis (Greece)


    Polymeric pH- and thermo-sensitive microcontainers (MCs) were developed as a potential drug delivery system for cancer therapy. It is well known that cancer cells exhibit notable characteristics such as acidic pH due to glycolytic cycle and higher temperature due to their higher proliferation rate. Based on these characteristics, we constructed a dual pH- and thermo-sensitive material for specific drug release on the pathological tissue. The MC's fabrication is based on a two-step procedure, in which, the first step involves the core synthesis and the second one is related to the shell formation. The core consists of poly(methyl methacrylate (PMMA), while the shell consists of PMMA, poly(isopropylacrylamide), poly(acrylic acid) and poly(divinylbenzene). Three different types of MCs were synthesized based on the seed polymerization method. The synthesized MCs were characterized structurally by Fourier transform infrared and morphologically by scanning electron microscopy. Dynamic light scattering was also used to study their behavior in aqueous solution under different pH and temperature conditions. For the loading and release study, the anthracycline drug daunorubicin (DNR) was used as a model drug, and its release properties were evaluated under different pH and thermo-conditions. Cytotoxicity studies were also carried out against MCF-7 breast cancer and 3T3 mouse embryonic fibroblast cells. According to our results, the synthesized microcontainers present desired pH and thermo behavior and can be applied in drug delivery systems. It is worth mentioning that the synthesized microcontainers which incorporated the drug DNR exhibit higher toxicity than the free drug. - Highlights: • Synthesis and characterization of biocompatible triggered microcontainers (MCs) • pH- and thermo-responsive co-polymers • Loading and release study: mechanism • MC's toxicity on healthy and cancer cell lines • IC{sub 50} determination.

  14. A ghost story: spatio-temporal response characteristics of an indirect-detection flat-panel imager.

    Siewerdsen, J H; Jaffray, D A


    Spatial and temporal imaging characteristics of an amorphous silicon flat-panel imager (FPI) were investigated in terms relevant to the application of such devices in cone-beam computed tomography (CBCT) and other x-ray imaging modalities, including general radiography, fluoroscopy, mammography, radiotherapy portal imaging, and nondestructive testing. Specifically, issues of image lag (including the magnitude, spatial uniformity, temporal-frequency characteristics, and dependence upon exposure and frame time) and long-term image persistence ("ghosts") were investigated. As part of the basic characterization of the FPI, pixel dark signal and noise (magnitude, temporal stability, and spatial uniformity) as well as radiation response (signal size, linearity, gain, and reciprocity) were also measured. Image lag was analyzed as a function of frame time and incident exposure. First-frame lag (i.e., the relative residual signal in the first frame following readout of an exposure) was approximately 2-10%, depending upon incident exposure and was spatially nonuniform to a slight degree across the FPI; second-, third-, and fourth-frame lag were approximately 0.7%, 0.4%, and 0.3%, respectively (at 25% sensor saturation). Image lag was also analyzed in terms of the temporal-frequency-dependent transfer function derived from the radiation response, allowing a quantitative description of system components contributing to lag. Finally, the contrast of objects as a function of time following an exposure was measured in order to examine long-term image persistence ("ghosts"). Ghosts were found to persist up to 30 min or longer, depending upon the exposure and frame time. Two means of reducing the apparent contrast of ghost images were tested: (i) rapid scanning of the FPI at maximum frame rate, and (ii) flood-field exposure of the FPI; neither was entirely satisfactory. These results pose important considerations for application of FPIs in CBCT as well as other x-ray imaging

  15. High glycemic and insulinemic responses to meals affect plasma growth hormone secretory characteristics in Quarter Horse weanlings.

    Gray, S M; Bartell, P A; Staniar, W B


    Growth hormone is a key component of the somatotropic axis and is critical for the interplay between nutrition, regulation of metabolic functions, and subsequent processes of growth. The objective of this study was to investigate potential relations between meal feeding concentrates differing in the glycemic responses they elicit and GH secretory patterns in young growing horses. Twelve Quarter Horse weanlings (5.4 ± 0.4 mo of age) were used in a crossover design, consisting of two 21-d periods and two treatments, a high-glycemic (HG) or low-glycemic (LG) concentrate meal, fed twice daily. Horses were individually housed and fed hay ad libitum. On the final day of each period, quarter-hourly blood samples were drawn for 24 h to measure plasma glucose, insulin, non-esterified fatty acids, and GH. Growth hormone secretory characteristics were estimated with deconvolution analysis. After a meal, HG-fed horses exhibited a longer inhibition until the first pulse of GH secretion (P = 0.012). During late night hours (1:00 AM to 6:45 AM), HG horses secreted a greater amount of pulsatile GH than LG horses (P = 0.002). These differences highlight the potential relations between glycemic and insulinemic responses to meals and GH secretion. Dietary energy source and metabolic perturbations associated with feeding HG meals to young, growing horses have the potential to alter GH secretory patterns compared with LG meals. This may potentially affect the developmental pattern of various tissues in the young growing horse. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Human disturbances, habitat characteristics and social environment generate sex-specific responses in vigilance of Mediterranean mouflon.

    Benoist, Stéphanie; Garel, Mathieu; Cugnasse, Jean-Marc; Blanchard, Pierrick


    In prey species, vigilance is an important part of the decision making process related to predation risk effects. Therefore, understanding the mechanisms shaping vigilance behavior provides relevant insights on factors influencing individual fitness. We investigated the role of extrinsic and intrinsic factors on vigilance behavior in Mediterranean mouflon (Ovis gmelini musimon×Ovis sp.) in a study site spatially and temporally contrasted in human pressures. Both sexes were less vigilant in the wildlife reserve compared to surrounding unprotected areas, except for males during the hunting period. During this period, males tended to be less strictly restricted to the reserve than females what might lead to a pervasive effect of hunting within the protected area, resulting in an increase in male vigilance. It might also be a rutting effect that did not occur in unprotected areas because males vigilance was already maximal in response to human disturbances. In both sexes, yearlings were less vigilant than adults, probably because they traded off vigilance for learning and energy acquisition and/or because they relied on adult experience present in the group. Similarly, non-reproductive females benefited of the vigilance effort provided by reproductive females when belonging to the same group. However, in the absence of reproductive females, non-reproductive females were as vigilant as reproductive females. Increasing group size was only found to reduce vigilance in females (up to 17.5%), not in males. We also showed sex-specific responses to habitat characteristics. Females increased their vigilance when habitat visibility decreased (up to 13.8%) whereas males increased their vigilance when feeding on low quality sites, i.e., when concomitant increase in chewing time can be devoted to vigilance with limited costs. Our global approach was able to disentangle the sex-specific sources of variation in mouflon vigilance and stressed the importance of reserves in managing

  17. Human disturbances, habitat characteristics and social environment generate sex-specific responses in vigilance of Mediterranean mouflon.

    Stéphanie Benoist

    Full Text Available In prey species, vigilance is an important part of the decision making process related to predation risk effects. Therefore, understanding the mechanisms shaping vigilance behavior provides relevant insights on factors influencing individual fitness. We investigated the role of extrinsic and intrinsic factors on vigilance behavior in Mediterranean mouflon (Ovis gmelini musimon×Ovis sp. in a study site spatially and temporally contrasted in human pressures. Both sexes were less vigilant in the wildlife reserve compared to surrounding unprotected areas, except for males during the hunting period. During this period, males tended to be less strictly restricted to the reserve than females what might lead to a pervasive effect of hunting within the protected area, resulting in an increase in male vigilance. It might also be a rutting effect that did not occur in unprotected areas because males vigilance was already maximal in response to human disturbances. In both sexes, yearlings were less vigilant than adults, probably because they traded off vigilance for learning and energy acquisition and/or because they relied on adult experience present in the group. Similarly, non-reproductive females benefited of the vigilance effort provided by reproductive females when belonging to the same group. However, in the absence of reproductive females, non-reproductive females were as vigilant as reproductive females. Increasing group size was only found to reduce vigilance in females (up to 17.5%, not in males. We also showed sex-specific responses to habitat characteristics. Females increased their vigilance when habitat visibility decreased (up to 13.8% whereas males increased their vigilance when feeding on low quality sites, i.e., when concomitant increase in chewing time can be devoted to vigilance with limited costs. Our global approach was able to disentangle the sex-specific sources of variation in mouflon vigilance and stressed the importance of

  18. Response characteristics of HPR1000 primary circuit under different working conditions of the atmospheric relief system after SBLOCA

    Sui, Danting, E-mail: [School of Nuclear Science and Engineering, North China Electric Power University, Beijing (China); Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy, North China Electric Power University, Beijing (China); Lu, Daogang [School of Nuclear Science and Engineering, North China Electric Power University, Beijing (China); Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy, North China Electric Power University, Beijing (China); Shang, Changzhong; Wei, Yuanyuan [China Nuclear Power Design Co., ltd (ShenZhen), Shenzhen (China); Zhang, Xianjie [School of Nuclear Science and Engineering, North China Electric Power University, Beijing (China); Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy, North China Electric Power University, Beijing (China)


    Highlights: • Response of HPR1000 under different VDA conditions after SBLOCA was investigated. • Activation of VDA can trigger ACCU SI earlier with a critical point exists. • VDA capability design should compromise the critical point with reactivity feedback. - Abstract: To cope with SBLOCA in absence of High-Head Safety Injection (HHSI) from design of HPR1000, atmospheric relief system (originally named as VDA in French) is uniquely designed to help to trigger Middle Head Safety Injection (MHSI) or Low Head Safety Injection (LHSI) earlier through cooling primary system quickly after SBLOCA. To make the best use of VDA decay heat removal capability, primary and secondary system of HPR1000 was modeled with RELAP5/SCDAP computer code. After steady-state initialization, a cold leg 30 mm break SBLOCA was simulated with six simulation conditions and five additional cases including availability of ACCU, different VDA discharge locations and area. Response characteristics of primary loop under different VDA working conditions are investigated. Pressurizer pressure decreases rapidly to lower level to trigger the reactor scram, VDA activation and accumulator safety injection sequently. Peak cladding temperature is 899.45 K occurring at 222 s, which is far below the safety limit. Activation of VDA can trigger ACCU SI earlier with a critical point, while positive reactivity will be introduced due to negative moderator temperature effect and Doppler effect. Larger VDA discharge capability will introduce larger reactivity feedback, as well as induce lower core level and SG level. It's suggested that VDA discharge condition should be chosen before the critical point, with the compromise with reactivity feedback introduced due to the negative moderator temperature effect.

  19. Biosynthetic hydrogels--studies on chemical and physical characteristics on long-term cellular response for tissue engineering.

    Thankam, Finosh Gnanaprakasam; Muthu, Jayabalan


    Biosynthetic hydrogels can meet the drawbacks caused by natural and synthetic ones for biomedical applications. In the current article we present a novel biosynthetic alginate-poly(propylene fumarate) copolymer based chemically crosslinked hydrogel scaffolds for cardiac tissue engineering applications. Partially crosslinked PA hydrogel and fully cross linked PA-A hydrogel scaffolds were prepared. The influence of chemical and physical (morphology and architecture of hydrogel) characteristics on the long term cellular response was studied. Both these hydrogels were cytocompatible and showed no genotoxicity upon contact with fibroblast cells. Both PA and PA-A were able to resist deleterious effects of reactive oxygen species and sustain the viability of L929 cells. The hydrogel incubated oxidative stress induced cells were capable of maintaining the intra cellular reduced glutathione (GSH) expression to the normal level confirmed their protective effect. Relatively the PA hydrogel was found to be unstable in the cell culture medium. The PA-A hydrogel was able to withstand appreciable cyclic stretching. The cyclic stretching introduced complex macro and microarchitectural features with interconnected pores and more structured bound water which would provide long-term viability of around 250% after the 24th day of culture. All these qualities make PA-A hydrogel form a potent candidate for cardiac tissue engineering.

  20. Characteristics analysis and dynamic responses of micro-gas-lubricated journal bearings with a new slip model

    Zhang, Wen-Ming; Meng, Guang; Huang, Hai; Zhou, Jian-Bin; Chen, Jie-Yu; Chen, Di


    In this paper, a new slip model based on kinetic theory of gases for gas-lubricated journal bearings in micro-electro-mechanical systems (MEMS) is applied using a physical approach. The corresponding modified governing equation and mathematic model are presented and the flow rate is plotted versus the inverse Knudsen number. Pressure distributions along the gas bearing at various Knudsen numbers and bearing numbers are plotted and the load carrying capacities are also obtained. A numerical analysis of a rigid rotor supported by gas-lubricated journal bearings is presented for dynamic behaviour. The slip flow effect on the properties, including pressure distribution, load carrying capacity and dynamic coefficients, of the micro-gas-lubricated journal bearings and dynamic responses of the micro rotor-bearing system are estimated and analysed in detail. It is shown that the dynamic coefficients increase with increasing bearing number except for two damping coefficients and the rotor-bearing system runs at a much higher rotating speed to keep stable when slip flow occurs. Moreover, the oscillation period of the rotor operating with the slip model is longer than that with the continuum flow. In addition, the whirl frequency is reduced from 0.422 to 0.079 under the slip effect. Therefore, the results of this study contribute to a further understanding of the characteristics and nonlinear dynamics of gas-film rotor-bearing systems in MEMS.


    Vabishchevych М.О.


    Full Text Available The paper considers the investigation of the features of stress-strain state of the structure with heterogeneous physical and mechanical properties on the example of the finite element calculation model of soil arch, which is reinforced by composite reinforcing cage.

  2. Swelling characteristics of immersed sand-bentonite mixtures

    丰土根; 崔红斌; 孙德安; 杜冰


    A laboratory one-dimensional consolidation apparatus was employed to research the swelling stress and volume of the sand-bentonite mixture under immersed conditions. The stress-strain characteristics of mixtures under varied mixing ratios and loading statuses were analyzed. Based on the results of tests, the mechanism of mixture swelling and collapsing was further discussed. The results show that mixtures with low sand ratios are suitable as hydraulic barrier or containment barriers of general landfills, geological repository and other hydraulic infrastructure works.


    Sanjin Troha


    Full Text Available The modern construction concept and the determination of the machine system characteristics anticipate CAD design. Creating model that will be tested using FEM and other methods for determining stress-strain is a very important part of rail vehicle construction. Applicative software package consists of linear and non–linear methods for the prediction of railway vehicle behavior and various methods of analysis have been assembled into a single coherent package in order to allow real problems in railway vehicle dynamics to be solved.

  4. Stress-Strain Relationship of High-Strength Steel Fiber Reinforced Concrete in Compression%钢纤维高强混凝土单轴压缩下应力应变关系

    严少华; 钱七虎; 孙伟; 尹放林


    在实际工程中推广应用钢纤维高强混凝土,要了解其基本力学性能.采用MTS815.03型液压伺服刚性压力试验机,对钢纤维含量为0~6%、抗压强度在65~120MPa范围的4种钢纤维高强混凝土,进行单轴压缩荷载作用下的应力应变全过程试验.结合试验给出全曲线的方程,并分析钢纤维对抗压强度、弹性模量、韧度、泊松比等的影响.试验表明,当钢纤维长度大于或接近于最大集料尺寸时,钢纤维高强混凝土具有较高的抗压强度和韧度,是一种优良的新型建筑材料.%It is necessary to research the basic mechanical performance inorder to use high-strength steel fiber reinforced concrete (HSFC) in practical engineering. Tests are conducted to characterize the stress-strain relationship of HSFC in compression by MTS815.03 rock testing machine. The concrete strength investigated ranges from 65 to 120 MPa and the volume fraction of steel fiber ranges from 0 to 6%. Based on the test data, an analytical model is proposed to generate the complete stress-strain curve for HSFC. The elastic modulus and toughness and Poisson’s ration of HSFC are also calculated in this paper. It is also proved by tests that HSFC is a good building material with high strength and high toughness when steel fibers are longer than the size of aggregate in concrete.

  5. Procedure to Determine Thermal Characteristics and Groundwater Influence in Heterogeneous Subsoil by an Enhanced Thermal Response Test and Numerical Modeling

    Aranzabal, Nordin; Martos, Julio; Montero, Álvaro; Monreal, Llúcia; Soret, Jesús; Torres, José; García-Olcina, Raimundo


    Ground thermal conductivity and borehole thermal resistance are indispensable parameters for the optimal design of subsoil thermal processes and energy storage characterization. The standard method to determine these parameters is the Thermal Response Test (TRT) which results are evaluated by models considering the ground being homogeneous and isotropic. This method obtains an effective ground thermal conductivity which represents an average of the thermal conductivity along the different layers crossed by perforation. In order to obtain a ground thermal conductivity profile as a function of depth two additional key factors are required, first, a new significant data set: a temperature profile along the borehole; and second, a new analysis procedure to extract ground heterogeneity from the recorded data. This research work presents the results of an analysis procedure, complementing the standard TRT analysis, which allows to estimate the thermal conductivity profile from a temperature profile measured along the borehole during a TRT. In the analysis procedure, a 3D Finite Element Model (FEM) is used to fit simulation results with experimental data, by a set of iterative simulations. This methodology is applied to a data set obtained throughout a TRT of 1kW heat power injection in a 30m depth Borehole Heat Exchange (BHE) facility. A highly conductive layer have been detected and located at 25 m depth. In addition, a novel automated device to obtain temperature profiles along geothermal pipes with or without fluid flow is presented. This sensor system is intended to improve the standard TRT and it allows the collection of depth depending thermal characteristics of the subsoil geological structure. Currently, some studies are being conducted in double U-pipe borehole installations in order to improve previously introduced analysis procedure. From a numerical model simulation that takes into account advective effects is pretended to estimate underground water velocity

  6. Early- and Late-Onset Depression in Late Life: A Prospective Study on Clinical and Structural Brain Characteristics and Response to Electroconvulsive Therapy.

    Dols, Annemiek; Bouckaert, Filip; Sienaert, Pascal; Rhebergen, Didi; Vansteelandt, Kristof; Ten Kate, Mara; de Winter, Francois-Laurent; Comijs, Hannie C; Emsell, Louise; Oudega, Mardien L; van Exel, Eric; Schouws, Sigfried; Obbels, Jasmien; Wattjes, Mike; Barkhof, Frederik; Eikelenboom, Piet; Vandenbulcke, Mathieu; Stek, Max L


    The clinical profile of late-life depression (LLD) is frequently associated with cognitive impairment, aging-related brain changes, and somatic comorbidity. This two-site naturalistic longitudinal study aimed to explore differences in clinical and brain characteristics and response to electroconvulsive therapy (ECT) in early- (EOD) versus late-onset (LOD) late-life depression (respectively onset characteristics were not different between EOD and LOD. Response to ECT was associated with late age at onset and presence of psychotic symptoms and not with structural MRI characteristics. In EOD only, the odds for a higher response were associated with a shorter index episode. The clinical profile, somatic comorbidities, and brain characteristics in LLD were similar in EOD and LOD. Nevertheless, patients with LOD showed a superior response to ECT compared with patients with EOD. Our results indicate that ECT is very effective in LLD, even in vascular burdened patients. Copyright © 2017 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.

  7. Correlation of Electrical Resistance to CMC Stress-Strain and Fracture Behavior Under High Heat-Flux Thermal and Stress Gradients

    Appleby, Matthew; Morscher, Gregory; Zhu, Dongming


    Because SiCSiC ceramic matrix composites (CMCs) are under consideration for use as turbine engine hot-section components in extreme environments, it becomes necessary to investigate their performance and damage morphologies under complex loading and environmental conditions. Monitoring of electrical resistance (ER) has been shown as an effective tool for detecting damage accumulation of woven melt-infiltrated SiCSiC CMCs. However, ER change under complicated thermo-mechanical loading is not well understood. In this study a systematic approach is taken to determine the capabilities of ER as a relevant non-destructive evaluation technique for high heat-flux testing, including thermal gradients and localized stress concentrations. Room temperature and high temperature, laser-based tensile tests were conducted in which stress-dependent damage locations were determined using modal acoustic emission (AE) monitoring and compared to full-field strain mapping using digital image correlation (DIC). This information is then compared with the results of in-situ ER monitoring, post-test ER inspection and fractography in order to correlate ER response to convoluted loading conditions and damage evolution.

  8. Isothermal recovery response and constitutive model of thermoset shape memory polymers

    Tan, Huifeng; Zhou, Tao; Liu, Yuyan; Lan, Lan


    Deformation recovery capability is one of the important indexes to examination shape memory effect of the shape memory polymers (SMPs). And the shape memory characteristic of SMPs is closely related to different phase states and mechanical properties above and below the glass transition temperature (Tg). In this paper, we investigated the strain recovery response of a thermoset shape memory epoxy resin modified by polyurethane (PU) through uniaxial compression experiments under various isothermal conditions and strain rates and developed a "three-phase" constitutive model based on phase transition concept, which including stationary phase, active phase and frozen phase. This model established the mutual transformation relationships between frozen phase and active phase of SMPs by introducing temperature switch function, which presents the stain storage and release process of SMPs under loading and changing temperature environment. Besides, the proposed model represents the SMPs deformation process of viscous hysteresis response by employing the rheological elements description of the three phases. The numerical results agree very well with experiment results of stress-strain response curve of isothermal compression/unloading test, which validated this model can predict the finite deformation behavior of SMPs.

  9. Inverse Analysis Method to Determine Twinning Kinetics Model Using Stress-Strain Curve%应力应变曲线逆分析确定孪生动力学模型

    李立新; 胡盛德; 叶奔


    To determine the twinning kinetics and the influence of twins on dislocation density and flow stress of 304 stainless steel, a constitutive relation model including the twinning kinetics was established by using dislocation theory and the stress-strain curve measured. The undetermined coefficients in this model were optimized by the tensile test data. Therefore, the model of twinning kinetics was obtained. Results for the model show that the dislocation density and flow stress increase rapidly with the increase of deformation when twins exist.%为确定304不锈钢的孪生动力学模型及孪生对位错密度和变形抗力的影响规律,利用位错理论建立了含材料孪生动力学关系的本构关系模型,实测了材料的应力应变曲线,运用实测结果优化确定了本构关系模型中的待定常数,进而建立了材料的孪生动力学关系模型,本构关系模型还表明,在孪生条件下,材料的位错密度及变形抗力随变形程度增加而快速增大.

  10. Physical-chemical characteristics and fatty acids composition in dairy goat milk in response to roughage diet

    Marcelo Shizuo Torii


    Full Text Available The objective of the present work was to evaluate the physical-chemical characteristics (density, pH, acidity, fat, protein, lactose and total of solids contents and milk fatty acids composition (C: 4 to C: 20 in response to roughage sources (alfalfa hay T1; oat hay T2 and maize silage T3. Nine Saanen lactating goats were used, in a triple Youden square design (3 animals x 2 periods. There was no treatment effects in the physical-chemical variables in the univariate analyses; by multivariate analyses three distinct patterns of fatty acids could be defined: milk with greater quantity of short chain fatty acids and acids C17:1omega7 e C18:2omega6 (T1; milk with equivalent amounts of short, medium and long chain fatty acids (T2; and milk with greater amounts of acids C16:1omega7, C17:0, C18:1omega9 and C20:0 (T3. These results indicated that the roughage sources used in the diet of lactating dairy goats affected the fatty acids composition, without altering the milk physical-chemical characteristics. The acids more sensitive to the treatment effects were: C10:0, C12:0, C14:0, C16:0, C16:1omega7, C18:0 and C18:3omega6.O presente trabalho teve por objetivo avaliar o efeito de fontes de volumosos (feno de alfafa T1; feno de aveia T2 e silagem de milho T3 nas características físico-químicas (densidade, pH, acidez, teores de gordura, proteína, lactose e sólidos totais e composição em ácidos graxos (C:4 a C:20 do leite. Foram utilizadas 9 cabras Saanen em lactação, em delineamento experimental triplo quadrado de Youden (3 animais x 2 períodos. Não houve efeito (P>0,05 dos tratamentos nas variáveis físico-químicas. Através de análise multivariada, verificou-se três padrões distintos de ácidos graxos: leite com maior quantidade de ácidos graxos de cadeia curta e dos ácidos C17:1ômega7 e C18:2ômega6 (T1; leite com quantidades equivalentes de ácidos graxos de cadeia curta, média e longa (T2 e leite com maiores quantidades dos

  11. Response surface optimization for enhanced production of cellulases with improved functional characteristics by newly isolated Aspergillus niger HN-2.

    Oberoi, Harinder Singh; Rawat, Rekha; Chadha, Bhupinder Singh


    Fungi isolated from partially decayed wood log samples showing characteristic diversity for spore colour, colony morphology and arrangement of spores were assessed for cellulolytic enzyme production. Isolates showing a cellulolytic index of ≥2.0 were assayed for filter paper (FP) cellulase and β-glucosidase (BGL) production. Molecular characterization confirmed the identity of the selected cellulolytic isolate as a strain of Aspergillus niger (A. niger HN-2). Addition of 2 % (w/v) urea enhanced FP and BGL activity by about 20 and 60 %, respectively. Validation studies conducted at parameters (29 °C, pH 5.4, moisture content 72 % and 66 h) optimized through response surface methodology in a solid-state static tray fermentation resulted in FP, BGL, cellobiohydrolase I (CBHI), endoglucanase (EG), xylanase activity and protein content of 25.3 FPU/g ds, 750 IU/g ds, 13.2 IU/g ds, 190 IU/g ds, 2890 IU/g ds and 0.9 mg/ml, respectively. In comparison, A. niger N402 which is a model organism for growth and development studies, produced significantly lower FP, BGL, CBHI, EG, xylanase activity and protein content of 10.0 FPU/g ds, 100 IU/g ds, 2.3 IU/g ds, 50 IU/g ds, 500 IU/g ds and 0.75 mg/ml, respectively under the same process conditions as were used for A. niger HN-2. Process optimization led to nearly 1.8- and 2.2-fold increase in FP and BGL activity, respectively showing promise for cellulase production by A. niger HN-2 at a higher scale of operation. Zymogram analysis revealed two isoforms each for EG and cellobiohydrolase and three isoforms for BGL. Crude cellulase complex produced by A. niger HN-2 exhibited thermostability under acidic conditions showing potential for use in biofuel industry.

  12. Acute cold hypersensitivity characteristically induced by oxaliplatin is caused by the enhanced responsiveness of TRPA1 in mice

    Zhao Meng


    . Conclusions Taken together, these results suggest that a brief treatment with oxaliplatin or its metabolite oxalate is sufficient to enhance the responsiveness of TRPA1 but not that of TRPM8 and TRPV1 expressed by DRG neurons, which may contribute to the characteristic acute peripheral neuropathy induced by oxaliplatin.

  13. How do hospital-specialty characteristics influence health system responsiveness? An empirical evaluation of in-patient care in the Italian region of Emilia-Romagna.

    Fiorentini, Gianluca; Robone, Silvana; Verzulli, Rossella


    Studies of health system responsiveness mostly focus on the demand side by investigating the association between sociodemographic characteristics of patients and their reported level of responsiveness. However, little is known about the influence of supply-side factors. This paper addresses that research gap by analysing the role of hospital-specialty characteristics in explaining variations in patients' evaluation of responsiveness from a sample of about 38,700 in-patients treated in public hospitals within the Italian Region of Emilia-Romagna. The analysis is carried out by adopting a 2-step procedure. First, we use patients' self-reported data to derive 5 measures of responsiveness at the hospital-specialty level. By estimating a generalised ordered probit model, we are able to correct for variations in individual reporting behaviour due to the health status of patients and their experience of being in pain. Second, we run cross-sectional regressions to investigate the association between patients' responsiveness and potential supply-side drivers, including waiting times, staff workload, the level of spending on non-clinical facilities, the level of spending on staff education and training, and the proportion of staff expenditure between nursing and administrative staff. Results suggest that responsiveness is to some extent influenced by the supply-side drivers considered. Copyright © 2017 John Wiley & Sons, Ltd.

  14. Tensile Deformation and Adiabatic Heating in Post-Yield Response of Polycarbonate


    strain histories for max and gage length and b) stress-strain behavior of PC at intermediate rate for max and gage length 8 3.4 Rate Effects on... frame . To determine the variations in yield and post-yield response at different locations of the gage area of the specimen, digital image...significant rate-sensitive mechanical response. 15. SUBJECT TERMS polycarbonate, tension, rate effects , thermal, heating 16. SECURITY CLASSIFICATION OF

  15. An Integrative Review of 21st-Century Roles, Responsibilities, Characteristics, and Competencies of Chief Nurse Executives: A Blueprint for the Next Generation.

    Crawford, Cecelia L; Omery, Anna; Spicer, Jerry

    Executive nursing practice is experiencing "head-snapping change." Health care has transitioned from the managed care era to the disruptive innovation era. As chief nurse executives (CNEs) navigate evolving care delivery models, they must consider retooling their roles and responsibilities related to emergent models. This integrative review's purpose was to examine evidence for the roles, responsibilities, characteristics, and competencies of CNEs and system CNEs to better guide future generations of nurse executives. Ganong and Cooper's integrative review methodology was chosen to guide the evidence synthesis. Seventeen articles were identified that pertained to the clinical inquiry. The evidence is inconsistent for specific CNE roles, responsibilities, characteristics, and competencies due to many areas of overlap and an absence of definitions. The evidence does describe who CNEs are, what they do, and how they articulate executive practice. Embedding evidence regarding emerging roles, responsibilities, characteristics, and competencies into the personal journeys of nurse executives helps articulate shifting paradigms and the CNE's role in transforming health care. Review results have the potential to create a blueprint for the recruitment, development, and retention of the next generation of nurse executives. New knowledge for the ever-changing worlds of CNEs is needed by robust research studies and other evidence.

  16. A survey of hospitals to determine the prevalence and characteristics of healthcare coalitions for emergency preparedness and response.

    Rambhia, Kunal J; Waldhorn, Richard E; Selck, Frederick; Mehta, Ambereen Kurwa; Franco, Crystal; Toner, Eric S


    Previous reports have identified the development of healthcare coalitions as the foundation for disaster response across the United States. This survey of acute care hospitals characterizes the current status of participation by US hospitals in healthcare coalitions for emergency preparedness planning and response. The survey results show the nearly universal nature of a coalition approach to disaster response. The results suggest a need for wide stakeholder involvement but also for flexibility in structure and organization. Based on the survey results, the authors make recommendations to guide the further development of healthcare coalitions and to improve local and national response to disasters.

  17. Differences in characteristics and patient-reported questionnaire responses in patients who choose non-surgical versus surgical treatment for severe hip osteoarthritis

    Have, Mads; Overgaard, Søren; Jensen, Carsten

    Background: Preoperative patient characteristics may influence patient choice for participating in RCT’s. Purpose / Aim of Study: This study aimed to compare patient characteristics, level of pain, physical function and joint space width in patients with severe hip osteoarthritis (OA) who accepted...... or refused to participate in a RCT. Materials and Methods: In this prospective cohort study a total of 137 patients with primary hip OA were asked to choose between surgical or non- surgical treatment. We then compared the characteristics of each patient cohort (demographics, pain level and duration......, analgesic use, exercise habits), the radiographic hip OA state and their responses to Hip dysfunction and Osteoarthritis Outcome Score (HOOS, 0-100) and European Quality of Life Scale (EQ-5D-5L) questionnaires. Findings / Results: The between-group HOOS scores were significantly different in three out...

  18. PNNL Stress/Strain Correlation for Zircaloy

    Geelhood, Kenneth J.; Beyer, Carl E.; Luscher, Walter G.


    Pacific Northwest National Laboratory (PNNL) was tasked with incorporating cladding mechanical property data into the Nuclear Regulatory Commission (NRC) fuel codes, FRAPCON-31 and FRAPTRAN2, by the NRC Office of Nuclear Reactor Research. The objective of that task was to create a mechanical model that can calculate true stress, true strain, and the possible failure of the fuel rod cladding based on uniaxial test data.

  19. Stress,strain and earthquake activity

    Yaolin Shi


    @@ There are 13 papers in this special issue on stress field,crustal deformation and seismicity.The great Wenchuan earthquake is a grievous disaster,but Chinese scientists are trying to learn more from the event in order to understand better the physics of earthquakes for future hazard mitigation planning.

  20. Predicting the influence of compressibility and thermal and flow distribution asymmetry on the frequency-response characteristics of multitube two-phase condensing flow systems

    Kobus, C.J.; Wedekind, G.L.; Bhatt, B.L.


    An equivalent single-tube model concept was extended to predict the frequency-response characteristics of multitube two-phase condensing flow systems, complete with the ability to predict the influence of compressibility and thermal and flow distribution asymmetry. The predictive capability of the equivalent single-tube model was verified experimentally with extensive data that encompassed a three-order-of-magnitude range of frequencies, and a wide range of operating parameters.

  1. Clinical Characteristics, Comorbidities, and Response to Treatment of Veterans With Obstructive Sleep Apnea, Cincinnati Veterans Affairs Medical Center, 2005-2007

    Samson, Pamela; Casey, Kenneth R.; Knepler, James; Panos, Ralph J.


    Introduction Obstructive sleep apnea (OSA) is a common disorder that is associated with significant morbidity. Veterans may be at an elevated risk for OSA because of increased prevalence of factors associated with the development and progression of OSA. The objective of this study was to determine the clinical characteristics, comorbidities, polysomnographic findings, and response to treatment of veterans with OSA. Methods We performed a retrospective chart review of 596 patients undergoing p...

  2. Fractional characteristic times and dissipated energy in fractional linear viscoelasticity

    Colinas-Armijo, Natalia; Di Paola, Mario; Pinnola, Francesco P.


    In fractional viscoelasticity the stress-strain relation is a differential equation with non-integer operators (derivative or integral). Such constitutive law is able to describe the mechanical behavior of several materials, but when fractional operators appear, the elastic and the viscous contribution are inseparable and the characteristic times (relaxation and retardation time) cannot be defined. This paper aims to provide an approach to separate the elastic and the viscous phase in the fractional stress-strain relation with the aid of an equivalent classical model (Kelvin-Voigt or Maxwell). For such equivalent model the parameters are selected by an optimization procedure. Once the parameters of the equivalent model are defined, characteristic times of fractional viscoelasticity are readily defined as ratio between viscosity and stiffness. In the numerical applications, three kinds of different excitations are considered, that is, harmonic, periodic, and pseudo-stochastic. It is shown that, for any periodic excitation, the equivalent models have some important features: (i) the dissipated energy per cycle at steady-state coincides with the Staverman-Schwarzl formulation of the fractional model, (ii) the elastic and the viscous coefficients of the equivalent model are strictly related to the storage and the loss modulus, respectively.

  3. The Application of Stress-Strain Test in Floor Damage Depth Testing%应力应变法在底板破坏深度测试中的应用

    周江东; 吕育强


    The floor aquiclude of Liu Jialiang coal mine in XuanGang area are faced with water inrush due to Ordovician high pressure water with mining. Controlling and preventing water inrush from coal floor had been the main task ,which need evaluate the floor damage depth under mining. Stress-strain test is used to detect the floor damage depth during mining as a new way, taking the ultimate strain of concrete when it is broken as the standard to evaluate the floor damage depth, good results was achieved that the floor damage depth was 13m Under full-mechanized caving mining.It provided reliable da-ta for rational evaluation of water inrush from floor under mining with pressure in working face 8416.%文中针对轩岗矿区刘家梁煤矿受底板下伏奥陶系灰岩岩溶裂隙水威胁的情况,指出当前底板突水防治成为矿井防治水的主要工作任务,需要探查回采工作对底板的破坏程度。通过采用应力应变法进行底板破坏深度测试,利用混凝土的破坏时产生的极限应变作为判断底板岩层破坏深度的依据,得到综放开采条件下采场底板破坏深度为13 m,为合理评价带压开采条件下8416工作面底板突水提供了可靠的数据支撑。

  4. Factorial analysis of variables influencing mechanical characteristics of a single tooth implant placed in the maxilla using finite element analysis and the statistics-based Taguchi method.

    Lin, Chun-Li; Chang, Shih-Hao; Chang, Wen-Jen; Kuo, Yu-Chan


    The aim of this study was to determine the relative contribution of changes (design factors) in implant system, position, bone classification, and loading condition on the biomechanical response of a single-unit implant-supported restoration. Non-linear finite-element analysis was used to simulate the mechanical responses in an implant placed in the maxillary posterior region. The Taguchi method was employed to identify the significance of each design factor in controlling the strain/stress. Increased strain values were noted in the cortical bone with lateral force and an implant with a retaining-screw connection. Cancellous bone strain was affected primarily by bone type and increased with decreasing bone density. Implant stress was influenced mainly by implant type and position. The combined use of finite-element analysis and the Taguchi method facilitated effective evaluation of the mechanical characteristics of a single-unit implant-supported restoration. Implants placed along the axis of loading exhibit improved stress/strain distribution. The reduction of lateral stress through implant placement and selective occlusal adjustment is recommended. An implant with a tapered interference fit connection performed better as a force-transmission mechanism than other configurations.

  5. The Influence of Infill Wall Topology and Seismic Characteristics on the Response and Damage Distribution in Frame Structures

    Nikos Nanos


    Full Text Available This paper identifies the effects of infill wall existence and arrangement in the seismic response of frame structures utilising the global structural damage index after Park/Ang (GDIPA and the maximum interstorey drift ratio (MISDR to express structural seismic response. Five different infill wall topologies of a 10-storey frame structure have been selected and analysed presenting an improved damage distribution model for infill wall bearing frames, hence promoting the use of nonstructural elements as a means of improving frame structural seismic behaviour and highlighting important aspects of structural response, demonstrating the suitability of such element implementation beyond their intended architectural scope.

  6. Lymphocyte Gene Expression Characteristic of Immediate Airway Responses (IAR) and Methacholine (MCH) Hyperresponsiveness in Mice Sensitized and Challenged with Isocyanates

    Exposure to isocyanates has been associated with occupational airway diseases, including asthma. Previously we reported on respiratory and immune responses following dermal sensitization and intranasal challenge of BALB/c mice with 6 different isocyanates. The purpose of this st...

  7. Effects of interdigitated platinum finger geometry on spectral response characteristics of germanium metal-semiconductor-metal photodetectors.

    Yang, Hyun-Duk; Janardhanam, V; Shim, Kyu-Hwan; Choi, Chel-Jong


    We fabricated interdigitated germanium (Ge) metal-semiconductor-metal photodetectors (MSM PDs) with interdigitated platinum (Pt) finger electrodes and investigated the effects of Pt finger width and spacing on their spectral response. An increase in the incident optical power enhances the creation of electron-hole pairs, resulting in a significant increase in photo current. Lowering of the Schottky barrier could be a main cause of the increase in both photo and dark current with increasing applied bias. The manufactured Ge MSM PDs exhibited a considerable spectral response for wavelengths in the range of 1.53-1.56 μm, corresponding to the entire C-band spectrum range. A reduction in the area fraction of the Pt finger electrode in the active region by decreasing and increasing finger width and spacing, respectively, led to an increase in illuminated active area and suppression of dark current, which was responsible for the improvement in responsivity and quantum efficiency of Ge MSM PDs.

  8. Modeling microstructural evolution and the mechanical response of superplastic materials

    Lesuer, D.R.; Syn, C.K.; Cadwell, K.L.; Preuss, C.S.


    A model has been developed that accounts for grain growth during, superplastic flow and its subsequent influence on stress-strain-strain rate behavior. These studies are experimentally based and have involved two different types of superplastic materials -- a quasi-single phase metal (Coronze 638) and a microduplex metal (ultrahigh-carbon steel - UHCS). In both materials the kinetics of strain-enhanced grain growth have been studied as a function of strain, strain rate and temperature. An equation for the rate of grain growth has been developed that incorporates the influence of temperature. The evolution of the grain size distribution during superplastic deformation has also been investigated. Our model integrates grain growth laws derived from these studies with two mechanism based, rate dependent constitutive laws to predict the stress-strainstrain rate behavior of materials during superplastic deformation. The influence of crain size distribution and its evolution with strain and strain rate on the stress-strain-strain rate behavior has been represented through the use of distributed parameters. The model can capture the stress-strain-strain rate behavior over a wide range of strains and strain rates with a single set of parameters. Many subtle features of the mechanical response of these materials can be adequately predicted.

  9. Steady State Rheological Characteristic of Semisolid Magnesium Alloy


    Isothermal compressive experiments at different temperatures, strain rates and holding time for semisolid AZ91D, Zr modified AZ91D and MB15 alloy with higher solid volume fraction were carried out by using Gleeble-15000 simulator and the true stress-strain curves were given directly. The relationship of apparent viscosity vs temperature, shear rate and holding time of the three kinds of semi-solid magnesium alloys, as well as isothermal steady state rheological characteristic and mechanical behavior were studied. The results show that the three magnesium alloys had the characteristic of shear-thinning. The rheological characteristic of the semi-solid MB15 is different from that of semi-solid AZ91D. The semi-solid MB15 has higher apparent viscosity and deformation resistance.

  10. Distinct Characteristics of Rye and Wheat Breads Impact on Their in Vitro Gastric Disintegration and in Vivo Glucose and Insulin Responses

    Nordlund, Emilia; Katina, Kati; Mykkänen, Hannu; Poutanen, Kaisa


    Disintegration of rye and wheat breads during in vitro gastric digestion and its relation to the postprandial glucose and insulin responses of the breads was studied. Breads with distinct composition and texture characteristics were prepared with refined or wholegrain wheat and rye flour by using either straight dough or sourdough process. After chewing and gastric digestion in vitro, 100% wholemeal and refined rye breads prepared by sourdough method were disintegrated to a much lower extent than the wheat breads, having more bread digesta particles with size over 2 or 3 mm. Microstructure of the digesta particles of rye sourdough bread revealed more aggregated and less degraded starch granules when compared to refined wheat bread. The postprandial insulin responses, but not those of glucose, to the 100% rye breads made with sourdough method were lower than the responses to the refined wheat bread. Addition of gluten or bran in rye sourdough bread increased insulin response. PCA (Principal Component Analysis) analysis confirmed that the insulin response had a negative correlation with the number of larger particles after in vitro digestion as well as amount of soluble fiber and sourdough process. Since the high relative proportion of large sized particles after chewing and in vitro gastric digestion was associated with low postprandial insulin responses, the analysis of structural disintegration in vitro is proposed as a complementary tool in predicting postprandial physiology. PMID:28231119

  11. Distinct Characteristics of Rye and Wheat Breads Impact on Their in Vitro Gastric Disintegration and in Vivo Glucose and Insulin Responses

    Emilia Nordlund


    Full Text Available Disintegration of rye and wheat breads during in vitro gastric digestion and its relation to the postprandial glucose and insulin responses of the breads was studied. Breads with distinct composition and texture characteristics were prepared with refined or wholegrain wheat and rye flour by using either straight dough or sourdough process. After chewing and gastric digestion in vitro, 100% wholemeal and refined rye breads prepared by sourdough method were disintegrated to a much lower extent than the wheat breads, having more bread digesta particles with size over 2 or 3 mm. Microstructure of the digesta particles of rye sourdough bread revealed more aggregated and less degraded starch granules when compared to refined wheat bread. The postprandial insulin responses, but not those of glucose, to the 100% rye breads made with sourdough method were lower than the responses to the refined wheat bread. Addition of gluten or bran in rye sourdough bread increased insulin response. PCA (Principal Component Analysis analysis confirmed that the insulin response had a negative correlation with the number of larger particles after in vitro digestion as well as amount of soluble fiber and sourdough process. Since the high relative proportion of large sized particles after chewing and in vitro gastric digestion was associated with low postprandial insulin responses, the analysis of structural disintegration in vitro is proposed as a complementary tool in predicting postprandial physiology.

  12. Tensodynamometric and spatial-temporal characteristics of defensive moving reaction of a law-enforcement officer in response to an attack of an armed enemy



    Full Text Available Purpose: to examine the tensodynamometric and spatial-temporal characteristics of a law-enforcement officer’s defensive movements in response to the moving attacking actions of an offender. To identify the efficient ways how to counter the attack of the enemy armed with the firearms. Material: It was surveyed 62 employees of practical units of law enforcement authorities. It was experimented with 15 cadets of Kyiv National Academy of Internal Affairs and 15 employees of Department of the State Guard of Ukraine. Results: As a result it was found out that the participants adapted to true-life armed conflicts with the offender. On the basis of the broadened knowledge about the outer indicators of the menace and spatial-temporal characteristics of the movements of the armed enemy it was created the moving behavior of the law-enforcement officer. Conclusions: In case of an armed enemy’s attack it is recommended to carry out the defensive action lunging aside with the optimum cooperation of supporting reactions and action in response, shooting on account of “muscle memory” of the angle of the pointed gun and the projection of the straight line in accordance with the gun tube, the target and the spatial characteristics.

  13. Hillslope-storage Boussinesq model for subsurface flow and variable source areas along complex hillslopes: 1. Formulation and characteristic response

    Troch, P.A.A.; Paniconi, C.; Loon, van E.E.


    Hillslope response to rainfall remains one of the central problems of catchment hydrology. Flow processes in a one-dimensional sloping aquifer can be described by Boussinesq's hydraulic groundwater theory. Most hillslopes, however, have complex three-dimensional shapes that are characterized by thei

  14. Effectiveness of Base Isolation Technique and Influence of Isolator Characteristics on Response of a Base Isolated Building

    Sunita Tolani


    Full Text Available This study concerns with the seismic response comparison of a fixed base building with a base isolated building and parametric study of a base isolated building. The structural system considered for analysis is a three storey reinforced concrete building, which is idealized as a shear type building with one lateral degree of freedom at each floor level. The isolation systems considered for this study are Laminated Rubber bearing (LRB, Lead Rubber Bearing (N-Z bearing and Friction Pendulum System (FPS. The response of fixed base building and of base isolated building is compared in terms of maximum top floor acceleration, interstorey drift, maximum floor displacements and base shear. For parametric study important isolation system parameters considered are: (i isolation time period, isolator damping for LRB; (ii isolator yield strength, isolation time period, isolator damping for N-Z bearing and (iii isolation time period, friction coefficient for FPS. It is found that base isolation technique is very effective in reducing seismic response of structure and isolation system parameters significantly influence the earthquake response of a base isolated structure.

  15. Trial-type probability and task-switching effects on behavioral response characteristics in a mixed saccade task.

    Pierce, Jordan E; McCardel, J Brett; McDowell, Jennifer E


    Eye movement circuitry involved in saccade production offers a model for studying cognitive control: visually guided prosaccades are stimulus-directed responses, while goal-driven antisaccades rely upon more complex control processes to inhibit the prepotent tendency to look toward a cue, transform its spatial location, and generate a volitional saccade in the opposite direction. By manipulating the relative probability of these saccade types, we measured participants' behavioral responses to different levels of implicit trial-type probability and task-switching demands in conditions with relatively long inter-trial fixation and trial-type cue lengths. Results indicated that when prosaccades were less probable in a run, more prosaccade errors were generated; however, for antisaccades, trial-type probability had no effect on the percent of correct responses. For reaction times, specifically in runs with a larger probability of antisaccade trials, latencies increased for both anti- and pro-saccades. Furthermore, task switching resulted in a lower percentage of correct responses on switched trials, but a prior antisaccade trial led to slower reaction times for both trial types (i.e., a task switch cost for prosaccades and switch benefit for antisaccades). These findings indicate that cognitive control demands and residual inhibition from antisaccades alter performance relative to trial-type probability and task switching within a run, with the prosaccade task showing greater susceptibility to the influence of a large probability of cognitively complex antisaccades.

  16. Auditory Brainstem Response Wave Amplitude Characteristics as a Diagnostic Tool in Children with Speech Delay with Unknown Causes

    Susan Abadi


    Full Text Available Speech delay with an unknown cause is a problem among children. This diagnosis is the last differential diagnosis after observing normal findings in routine hearing tests. The present study was undertaken to determine whether auditory brainstem responses to click stimuli are different between normally developing children and children suffering from delayed speech with unknown causes. In this cross-sectional study, we compared click auditory brainstem responses between 261 children who were clinically diagnosed with delayed speech with unknown causes based on normal routine auditory test findings and neurological examinations and had >12 months of speech delay (case group and 261 age- and sex-matched normally developing children (control group. Our results indicated that the case group exhibited significantly higher wave amplitude responses to click stimuli (waves I, III, and V than did the control group (P=0.001. These amplitudes were significantly reduced after 1 year (P=0.001; however, they were still significantly higher than those of the control group (P=0.001. The significant differences were seen regardless of the age and the sex of the participants. There were no statistically significant differences between the 2 groups considering the latency of waves I, III, and V. In conclusion, the higher amplitudes of waves I, III, and V, which were observed in the auditory brainstem responses to click stimuli among the patients with speech delay with unknown causes, might be used as a diagnostic tool to track patients’ improvement after treatment.

  17. Response characteristics of vibration-sensitive neurons in the midbrain of the grassfrog, Rana temporaria

    Christensen-Dalsgaard, J; Jørgensen, M B


    European grassfrogs (Rana temporaria) were stimulated with pulsed sinusoidal, vertical vibrations (10-300 Hz) and the responses of 46 single midbrain neurons were recorded in awake, immobilized animals. Most units (40) had simple V-shaped excitatory vibrational tuning curves. The distribution of ...

  18. Stress-strain analysis of contractility in the ileum in response to flow and ramp distension in streptozotocin-induced diabetic rats--association with advanced glycation end product formation.

    Zhao, Jingbo; Chen, Pengmin; Gregersen, Hans


    This study compared the ileal contractility and analyzed the association between contractility with advanced glycation end product (AGE) formation in normal and streptozotocin (STZ)-induced diabetic rats. Nine STZ-induced diabetic rats (Diabetes group) and 9 normal rats (Normal group) were used. The motility experiments were carried out on ileums in organ baths containing physiological Krebs solution. Ileal pressure and diameter changes were obtained from basic, flow-induced and ramp distension-induced contractions. The frequency and amplitude of contractions were analyzed from pressure-diameter curves. Distension-induced contraction thresholds and maximum contraction amplitude of basic and flow-induced contractions were calculated in terms of stress and strain. AGE and its receptor (RAGE) in the layers were detected by immunohistochemistry staining. The maximum stress of flow-induced contractions was lowest in the Diabetes Group (PYoung's modulus to induce phasic contraction were lowest in the Diabetes Group (Pmuscle layer and RAGE expression in mucosa epithelium and neurons. The diabetic intestine was hypersensitive to distension for contraction induction. However, the contraction force produced by smooth muscle was lowest in diabetic rats. Increased AGE/RAGE expression was associated with the contractility changes in diabetic rats. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Assessment of dyspnea early in acute heart failure: patient characteristics and response differences between likert and visual analog scales.

    Pang, Peter S; Collins, Sean P; Sauser, Kori; Andrei, Adin-Cristian; Storrow, Alan B; Hollander, Judd E; Tavares, Miguel; Spinar, Jindrich; Macarie, Cezar; Raev, Dimitar; Nowak, Richard; Gheorghiade, Mihai; Mebazaa, Alexandre


    Dyspnea is the most common symptom in acute heart failure (AHF), yet how to best measure it has not been well defined. Prior studies demonstrate differences in dyspnea improvement across various measurement scales, yet these studies typically enroll patients well after the emergency department (ED) phase of management. The aim of this study was to determine predictors of early dyspnea improvement for three different, commonly used dyspnea scales (i.e., five-point absolute Likert scale, 10-cm visual analog scale [VAS], or seven-point relative Likert scale). This was a post hoc analysis of URGENT Dyspnea, an observational study of 776 patients in 17 countries enrolled within 1 hour of first physician encounter. Inclusion criteria were broad to reflect real-world clinical practice. Prior literature informed the a priori definition of clinically significant dyspnea improvement. Resampling-based multivariable models were created to determine patient characteristics significantly associated with dyspnea improvement. Of the 524 AHF patients, approximately 40% of patients did not report substantial dyspnea improvement within the first 6 hours. Baseline characteristics were similar between those who did or did not improve, although there were differences in history of heart failure, coronary artery disease, and initial systolic blood pressure. For those who did improve, patient characteristics differed across all three scales, with the exception of baseline dyspnea severity for the VAS and five-point Likert scale (c-index ranged from 0.708 to 0.831 for each scale). Predictors of early dyspnea improvement differ from scale to scale, with the exception of baseline dyspnea. Attempts to use one scale to capture the entirety of the dyspnea symptom may be insufficient. © 2014 by the Society for Academic Emergency Medicine.

  20. Assessment of Dyspnea Early in Acute Heart Failure: Patient Characteristics and Response Differences Between Likert and Visual Analog Scales

    Pang, Peter S.; Collins, Sean P.; Sauser, Kori; Andrei, Adin-Cristian; Storrow, Alan B.; Hollander, Judd E.; Tavares, Miguel; Spinar, Jindrich; Macarie, Cezar; Raev, Dimitar; Nowak, Richard; Gheorghiade, Mihai; Mebazaa, Alexandre


    Background Dyspnea is the most common symptom in acute heart failure (AHF), yet how to best measure it has not been well defined. Prior studies demonstrate differences in dyspnea improvement across various measurement scales, yet these studies typically enroll patients well after the ED phase of management. Objectives The aim of this study was to determine predictors of early dyspnea improvement for three different, commonly used dyspnea scales (i.e. five point absolute Likert scale, 10 cm visual analogue scale [VAS], or seven point relative Likert scale). Methods This was a post-hoc analysis of URGENT Dyspnea, an observational study of 776 patients in 17 countries enrolled within one hour of first physician encounter. Inclusion criteria were broad to reflect real-world clinical practice. Prior literature informed the a priori definition of clinically significant dyspnea improvement. Resampling-based multivariable models were created to determine patient characteristics significantly associated with dyspnea improvement. Results Of the 524 AHF patients, approximately 40% of patients did not report substantial dyspnea improvement within the first 6 hours. Baseline characteristics were similar between those who did or did not improve, though there were differences in history of heart failure, coronary artery disease, and initial systolic blood pressure. For those who did improve, patient characteristics differed across all three scales, with the exception of baseline dyspnea severity for the VAS and five point Likert scale (c-index ranged from 0.708 to 0.831 for each scale). Conclusions Predictors of early dyspnea improvement differ from scale to scale, with the exception of baseline dyspnea. Attempts to use one scale to capture the entirety of the dyspnea symptom may be insufficient. PMID:25039550

  1. Characteristics of marine CSEM responses in complex geologic terrain of Niger Delta Oil province: Insight from 2.5D finite element forward modeling

    Folorunso, Adetayo F.; Li, Yuguo; Liu, Ying


    Mapping hydrocarbon reservoirs with sufficient resistivity contrasts between them and the surrounding layers has been demonstrated using marine Controlled Source Electromagnetic (mCSEM) technique in this study. The methodology was applied to the Niger Delta hydrocarbon province where resistive targets are located in a wide range of depths beneath variable seawater depths in the presence of heterogeneous overburden. An efficient 2.5D adaptive finite element (FE) forward modeling code was used to delineate the characteristics of the mCSEM responses on geological models; and to establish the suitable transmission and detectable frequencies for targets with variable seawater and burial depths. The models consist of three resistive hydrocarbon layers of 100 Ωm resistivity, two of which overlain each other. This presents an opportunity to study and understand the 2.5D marine CSEM responses such as the transmission frequency, transmitter-receiver-target geometry, seawater depth and burial depth of the resistive hydrocarbon layers that is characteristics of the region. We found that mCSEM response to two vertically-placed thin resistors is higher than that of the individual resistive layer, which could be a veritable tool to identify the two reservoirs, which would have been previously identified by seismic, as possible hydrocarbon layers. For the seawater depths model, detectability of the resistive hydrocarbon increases for the deeper models but decreases for the shallow anomalous depths (305-m and 500-m subsea). This is noticeable for all offsets in the electric filed amplitude responses. The responses are obvious and distinct for the long range electric fields models. The modeling results also indicates that lower frequencies produce high E-field amplitude though higher frequencies generate higher anomaly measured as normalized amplitude ratio (NAR). Generally, it was deduced that expanded frequency spectrum will be needed to significantly resolve thin resistive

  2. Comparison of a xenogeneic and an alloplastic material used in dental implants in terms of physico-chemical characteristics and in vivo inflammatory response

    Figueiredo, Andreia [Experimental Pathology Service, University of Coimbra, 3004-504 Coimbra (Portugal); Dentistry Department, University of Coimbra, 3030-005 Coimbra (Portugal); Catholic Portuguese University, Health Sciences Department, 3504-505 Viseu (Portugal); Coimbra, Patrícia, E-mail: [Chemical Engineering Department, University of Coimbra, 3030-290 Coimbra (Portugal); Cabrita, António [Experimental Pathology Service, University of Coimbra, 3004-504 Coimbra (Portugal); Guerra, Fernando [Dentistry Department, University of Coimbra, 3030-005 Coimbra (Portugal); Figueiredo, Margarida [Chemical Engineering Department, University of Coimbra, 3030-290 Coimbra (Portugal)


    Two commercial bone grafts used in dentistry (Osteobiol Gen-Os®, a xenograft of porcine origin, and Bonelike®, a hydroxyapatite based synthetic material), in the form of granules, were characterized and evaluated in vivo regarding the intensity of the tissue inflammatory response. These biomaterials were characterized in terms of morphology, particle size distribution, porosity and pore size, specific surface area and density. The chemical composition and structure of the materials were accessed by Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD). The graft materials were implanted in the gluteus maximus muscles of Wistar rats and the inflammatory response was evaluated through histological analysis, after one week of implantation. The results showed that the two grafts have quite different characteristics in practically all the evaluated properties. While Osteobiol® exhibits a structure and composition similar to the natural bone, Bonelike® is constituted by a main crystalline phase of hydroxyapatite and two secondary phases of α- and β-tricalcium phosphate. Osteobiol® granules, besides being larger, are irregular, and exhibit sharp-edged tips, while those of Bonelike® are approximately cylindrical, with round contours, and more uniform in size. The in vivo response evaluated from the inflammatory infiltrates revealed that although both implants did not cause severe inflammation, Bonelike® granules elicit a consistently more intense inflammatory reaction than that triggered by the granules of Osteobiol®, particularly in terms of collagen production and formation of fibrous capsule. This reaction was partly explained in terms of the characteristics evaluated for the granules of this material. - Highlights: • Two commercial bone grafts – Bonelike® and Osteobio® – were characterized. • In vivo inflammatory response was evaluated after 1 week implantation. • Both materials did not cause severe inflammation.

  3. Stimulus-response characteristics of a harbor porpoise during active echolocation and passive hearing studied with auditory brain stem recordings (ABR)

    Beedholm, Kristian; Miller, Lee A.


    We evaluated the stimulus-response characteristics of hearing by a harbor porpoise using narrow band pulses resembling the animal's own echolocation pulse (130 kHz, 100 us), but shifted in frequency (80, 100, 125, 160 kHz). Our animal was trained to accept two suction cup electrodes and to station 1 m below the water surface. Stimuli could be presented either as simulated echoes at a fixed delay (5 ms) relative to the animal's echolocation signals, or at a constant rate chosen by the experimenter. Stimulus levels were varied between 90 and 150 dB re 1uPa and the ABR responses were averaged (16 or more responses) at each level. The relationship between input level (in dB) and ABR amplitude was reasonably linear for simulated echo and constant rate experiments. Regression lines were calculated to determine the level at which the response met the noise, defining the ABR threshold. There was little difference in the ABR threshold (100 to 110 dB re 1uPa) for the four frequencies. The rate of growth of the ABR response with increasing stimulus level was steepest at 125 kHz, which could well reflect a relatively denser population of neurons tuned to this frequency area. [Work done at Fjord & Baelt, Kerteminde, Denmark, and supported by ONR.

  4. 责任旅游的时代特征及适应对策分析%Analysis of Era Characteristics of Responsible Tourism and Adapting Countermeasures

    周秉根; 张静; 张蕾; 潘金宝; 刘向阳; 陈建业; 何俊杰


    With the development of tourism industry, sense of responsibility in the tourism industry is increasing, hence the creation of responsible tourism. This paper first discusses the concept, connotation and significance of responsible tourism, and then analyzes the era characteristics and the adapting countermeasures of responsible tourism, for the purpose of raising the sense of responsibility of the tourism employers and employees, creating a civilized and harmonious environment of tourism, and promoting the healthy and orderly development of tourism industry.%随着旅游业的发展,旅游业中的责任性逐步增强.责任旅游也即应运而生.本文从责任旅游的概念、内涵和意义人手,重点分析了责任旅游的时代特征和责任旅游的适应对策.目的是提高旅游行业中的责任心,营造文明和谐的旅游环境,促进旅游业健康有序地发展.

  5. Composite exponential-sine model for dynamic stress-strain curve of soft soil%软土动应力-应变曲线复合指数-正弦模型

    王伟; 凌华; 孙斌祥


    软土动应力-应变曲线(DSSC)模型是土动力学研究中的一个重要课题。结合软土DSSC的试验规律,分析了其数学模型应具有的基本性质。以最终动强度和初始切线模量为基本参数,对传统双曲线模型和指数模型进行了数学分析。引入动强度因子的概念,揭示了两传统DSSC模型的缺陷。提出了一个软土DSSC复合指数-正弦模型,该模型是一个单调递增、外凸且有极限值的函数。数学分析表明,新模型克服了传统模型的不足,两传统模型均是新模型对应的特例。最后,给出了模型参数的确定方法,通过实测数据拟合验证了新模型的正确性。%Mathematical modeling of dynamic stress-strain curve(DSSC)is important to the study of dynamic behavior of soft soil.Based on an analysis of measured data,the required primary behaviors of DSSC model are analyzed.Ultimate dynamic strength and initial tangent modulus are used to analytically examine the conventional DSSC models,hyperbolic model and exponential model,and a dynamical stress index is proposed and adopted to show the shortcomings of these two models.A composite exponential-sine model of three parameters,or a monotonically increasing and convex function with an upper bound,is developed,and an approach for determinination of model parameters is presented.Mathematical analysis shows that this model can overcome the shortcomings of the two conventional models that are two special cases of the new model,and the modeling results agree with the measured data.

  6. Response of Somatal Characteristics and its Plasticity to Different Light Intensities in Leaves of Seven Tropical Woody Seedlings

    CAIZhiquan; QIXing; CAOKunfang


    Stomatal characteristics and its plasticity were surveyed in leaves of four canopy species, Shorea chinensis, Pometia tomentosa, Anthocephalus chinensis, Calophyllun polyanthum and three middle-layer species, Barringtonia pendula, Garcinia hanburyi, Horsfieldia tetratepala, acclimated to different light conditions for more than one year. All plant's stomata are distributed on the abaxial of leaves. Pometia tomentosa and Barringtonia pendula have higher stomatal density and the guard cell length of Anthocephalus chinensis and Calophyllun polyanthum were much greater than others'. Stomatal density and stomatal index (ratio of stomatal numbers to epidermal cell number) were increased with growth irradiance increased, while numbers of stomata per leaf were higher in the low than the high relative PFD, and stomatal conductance of leaves was the highest in the 50% of full light except for Anthocephalus chinensis. The relative PFD has little effects on the guard cell length of all seven plants. We have also found a significant negative correlation between stomatal density and leaf area, but the stomatal conductance was not significantly positive with the stomatal conductance. The analysis of phenotypic plasticity of stomatal characteristics showed: plasticity index for stomatal index and numbers of stomatal per leaf were similar for canopy and middle-layer species,while the plasticity index of stomatal density and stomatal conductance were significantly greater for canopy species than middle-layer species. The high plasticity of canopy species was consistent with the hypothesis that specialization in a more favorable environment increases plasticity.

  7. Bioinformatic Approaches Including Predictive Metagenomic Profiling Reveal Characteristics of Bacterial Response to Petroleum Hydrocarbon Contamination in Diverse Environments.

    Mukherjee, Arghya; Chettri, Bobby; Langpoklakpam, James S; Basak, Pijush; Prasad, Aravind; Mukherjee, Ashis K; Bhattacharyya, Maitree; Singh, Arvind K; Chattopadhyay, Dhrubajyoti


    Microbial remediation of oil polluted habitats remains one of the foremost methods for restoration of petroleum hydrocarbon contaminated environments. The development of effective bioremediation strategies however, require an extensive understanding of the resident microbiome of these habitats. Recent developments such as high-throughput sequencing has greatly facilitated the advancement of microbial ecological studies in oil polluted habitats. However, effective interpretation of biological characteristics from these large datasets remain a considerable challenge. In this study, we have implemented recently developed bioinformatic tools for analyzing 65 16S rRNA datasets from 12 diverse hydrocarbon polluted habitats to decipher metagenomic characteristics of the resident bacterial communities. Using metagenomes predicted from 16S rRNA gene sequences through PICRUSt, we have comprehensively described phylogenetic and functional compositions of these habitats and additionally inferred a multitude of metagenomic features including 255 taxa and 414 functional modules which can be used as biomarkers for effective distinction between the 12 oil polluted sites. Additionally, we show that significantly over-represented taxa often contribute to either or both, hydrocarbon degradation and additional important functions. Our findings reveal significant differences between hydrocarbon contaminated sites and establishes the importance of endemic factors in addition to petroleum hydrocarbons as driving factors for sculpting hydrocarbon contaminated bacteriomes.

  8. Characteristics and dynamic response analysis of 3-D component base isolation system using multi-layer-rubber-bearings and coil springs

    Tsutsumi, Hideaki; Yamada, Hiroyuki; Ebisawa, Katsumi; Shibata, Katsuyuki [Seismic Emergency Information System Research Team, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)


    Introduction of the base isolation technique into the seismic design of nuclear power plant components as well as buildings has been expected as one of effective countermeasure to reduce the seismic force applied to components. A research program of the base isolation of nuclear components has been carried out at Japan Atomic Energy Research Institute(JAERI) since 1991. A methodology and a computer code (EBISA: Equipment Base Isolation System Analysis) for evaluating the failure frequency of the nuclear component with the base isolation were developed. In addition, a test program, which is concerned with the above development, i.e., improvement of failure frequency analysis models in the code has been conducted since 1996 to investigate the dynamic behavior and to verify the effectiveness of component base isolation systems. Two kinds of base isolation test systems with different characteristic were fabricated and static and dynamic characteristics were measured by static loading and free vibration tests. One which consists of ball bearings and air springs was installed on the test bed to observe the dynamic response under natural earthquake motion. The effect of base isolation system has been observed under several earthquakes. Another system which consists of multi-layer-rubber-bearings and coil springs has been investigated three-dimensional dynamic behavior and effect of base isolation against various large earthquake motions by shaking table test. This report describes the design specification of the base isolation system which consists of multi-layer-rubber-bearings and coil springs, static and dynamic characteristics, analysis model based on the characteristics, results of shaking table test and the dynamic response analysis (author)

  9. Effects of electronic state modulation on the high-frequency response characteristics of GaAs quantum wells

    Basanta Singh, N., E-mail: [Department of Electronics and Communication Engineering, Manipur Institute of Technology, Imphal 795 004 (India); Deb, Sanjoy, E-mail: [Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata 700 032 (India); Sarkar, Subir Kumar, E-mail: [Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata 700 032 (India)


    The effect of electronic-state modulation on the high frequency response of GaAs quantum well with thin inserted barrier layer is studied. The carrier scattering by polar optic phonons, acoustic deformation potential and background ionized impurities are incorporated in the present calculations considering the carrier distribution to be heated drifted Fermi-Dirac distribution. Modified phonon spectra and modulated electron wave function give different values of form factor compared to bulk mode phonon. Mobility is found to be enhanced on insertion of thin layer inside the quantum well. The ac mobility and the phase lag increases with the increase in both the channel width and the 2D carrier concentration. Cutoff frequency, where ac mobility drops down to 0.707 of its low frequency value, is observed to be enhanced reflecting better high frequency response.

  10. Patient Characteristics Associated with HCV Treatment Adherence, Treatment Completion, and Sustained Virologic Response in HIV Coinfected Patients

    Glenn Wagner


    Full Text Available Background. Hepatitis C (HCV treatment efficacy among HIV patients is limited by poor treatment adherence and tolerance, but few studies have examined the psychosocial determinants of treatment adherence and outcomes. Methods. Chart abstracted and survey data were collected on 72 HIV patients who had received pegylated interferon and ribavirin to assess correlates of treatment adherence, completion, and sustained virologic response (SVR. Results. Nearly half (46% the sample had active psychiatric problems and 13% had illicit drug use at treatment onset; 28% reported <100% treatment adherence, 38% did not complete treatment (mostly due to virologic nonresponse, and intent to treat SVR rate was 49%. Having a psychiatric diagnosis was associated with nonadherence, while better HCV adherence was associated with both treatment completion and SVR. Conclusions. Good mental health may be an indicator of HCV treatment adherence readiness, which is in turn associated with treatment completion and response, but further research is needed with new HCV treatments emerging.

  11. Homology of olfactory receptor neuron response characteristics inferred from hybrids between Asian and European corn borer moths (Lepidoptera: Crambidae).

    Domingue, Michael J; Musto, Callie J; Linn, Charles E; Roelofs, Wendell L; Baker, Thomas C


    First generation hybrid males from crosses between the Asian corn borer (ACB), Ostrinia furnacalis, and the "univoltine Z-strain" European corn borer (ECB), Ostrinia nubilalis, were examined with respect to behavioral and physiological responses to ACB and ECB pheromones. The hybrid males often flew to the pheromone of ECB Z-strain, but very rarely to the ACB pheromone. We mapped the tuning profiles of each ORN of the F(1) hybrids with respect to the relevant pheromone components and a common behavioral antagonist by employing differential cross-adaptation and varying doses of the ligands. In the trichoid sensilla of F(1) hybrid males, the three co-compartmentalized ORNs produced spikes that were very difficult to distinguish by size, unlike the parental populations. Comparing the responses to ACB and ECB components at different doses reveals overlapping profiles similar to males of both parental types, but more responsiveness to the ECB pheromone components. We were unable to detect any differences in the ORN tuning profiles when comparing males with different behavioral phenotypes. While the two ECB pheromone races have similar ORN tuning properties that are different from those in ACB, the spike-amplitude patterns of ECB E-strain and ACB have greater homology when compared to ECB Z-strain.

  12. The Atypical Response Regulator Protein ChxR Has Structural Characteristics and Dimer Interface Interactions That Are Unique within the OmpR/PhoB Subfamily

    Hickey, John M.; Lovell, Scott; Battaile, Kevin P.; Hu, Lei; Middaugh, C. Russell; Hefty, P. Scott (Kansas); (HWMRI)


    Typically as a result of phosphorylation, OmpR/PhoB response regulators form homodimers through a receiver domain as an integral step in transcriptional activation. Phosphorylation stabilizes the ionic and hydrophobic interactions between monomers. Recent studies have shown that some response regulators retain functional activity in the absence of phosphorylation and are termed atypical response regulators. The two currently available receiver domain structures of atypical response regulators are very similar to their phospho-accepting homologs, and their propensity to form homodimers is generally retained. An atypical response regulator, ChxR, from Chlamydia trachomatis, was previously reported to form homodimers; however, the residues critical to this interaction have not been elucidated. We hypothesize that the intra- and intermolecular interactions involved in forming a transcriptionally competent ChxR are distinct from the canonical phosphorylation (activation) paradigm in the OmpR/PhoB response regulator subfamily. To test this hypothesis, structural and functional studies were performed on the receiver domain of ChxR. Two crystal structures of the receiver domain were solved with the recently developed method using triiodo compound I3C. These structures revealed many characteristics unique to OmpR/PhoB subfamily members: typical or atypical. Included was the absence of two {alpha}-helices present in all other OmpR/PhoB response regulators. Functional studies on various dimer interface residues demonstrated that ChxR forms relatively stable homodimers through hydrophobic interactions, and disruption of these can be accomplished with the introduction of a charged residue within the dimer interface. A gel shift study with monomeric ChxR supports that dimerization through the receiver domain is critical for interaction with DNA.

  13. Influence of Characteristic-Soil-Property-Estimation Approach on the Response of Monopiles for Offshore Wind Turbines

    Andersen, Lars Vabbersgaard; Sørensen, John Dalsgaard; Kim, Sun-Bin;


    , and pile–soil interaction is modelled by the Winkler approach with nonlinear p–y curves for the soil resistance. The 5MW NREL reference wind turbine is employed for load estimation, utilizing the aeroelastic code FAST. The study includes comparison of monopile capacities based on a single CPT as well......Different approaches to estimation of the characteristic undrained shear strength of soil are discussed, based on 12 cone penetration tests (CPTs) carried out within a soil volume representative of an offshore monopile foundation. The paper is focused on the statistical treatment of the data...... as multiple CPTs. Comparisons are made between results obtained from a single CPT and those from all the CPTs at the site. The influence of assuming few or many layers in the deterministic soil model is assessed, and different assumptions regarding the statistical distribution of the data are compared...

  14. pH- and thermo-responsive microcontainers as potential drug delivery systems: Morphological characteristic, release and cytotoxicity studies.

    Efthimiadou, Eleni K; Tapeinos, Christos; Tziveleka, Leto-Aikaterini; Boukos, Nikos; Kordas, George


    Polymeric pH- and thermo-sensitive microcontainers (MCs) were developed as a potential drug delivery system for cancer therapy. It is well known that cancer cells exhibit notable characteristics such as acidic pH due to glycolytic cycle and higher temperature due to their higher proliferation rate. Based on these characteristics, we constructed a dual pH- and thermo-sensitive material for specific drug release on the pathological tissue. The MC's fabrication is based on a two-step procedure, in which, the first step involves the core synthesis and the second one is related to the shell formation. The core consists of poly(methyl methacrylate (PMMA), while the shell consists of PMMA, poly(isopropylacrylamide), poly(acrylic acid) and poly(divinylbenzene). Three different types of MCs were synthesized based on the seed polymerization method. The synthesized MCs were characterized structurally by Fourier transform infrared and morphologically by scanning electron microscopy. Dynamic light scattering was also used to study their behavior in aqueous solution under different pH and temperature conditions. For the loading and release study, the anthracycline drug daunorubicin (DNR) was used as a model drug, and its release properties were evaluated under different pH and thermo-conditions. Cytotoxicity studies were also carried out against MCF-7 breast cancer and 3T3 mouse embryonic fibroblast cells. According to our results, the synthesized microcontainers present desired pH and thermo behavior and can be applied in drug delivery systems. It is worth mentioning that the synthesized microcontainers which incorporated the drug DNR exhibit higher toxicity than the free drug.

  15. Metabolomics reveals differences in postprandial responses to breads and fasting metabolic characteristics associated with postprandial insulin demand in postmenopausal women.

    Moazzami, Ali A; Shrestha, Aahana; Morrison, David A; Poutanen, Kaisa; Mykkänen, Hannu


    Changes in serum metabolic profile after the intake of different food products (e.g., bread) can provide insight into their interaction with human metabolism. Postprandial metabolic responses were compared after the intake of refined wheat (RWB), whole-meal rye (WRB), and refined rye (RRB) breads. In addition, associations between the metabolic profile in fasting serum and the postprandial concentration of insulin in response to different breads were investigated. Nineteen postmenopausal women with normal fasting glucose and normal glucose tolerance participated in a randomized, controlled, crossover meal study. The test breads, RWB (control), RRB, and WRB, providing 50 g of available carbohydrate, were each served as a single meal. The postprandial metabolic profile was measured using nuclear magnetic resonance and targeted LC-mass spectrometry and was compared between different breads using ANOVA and multivariate models. Eight amino acids had a significant treatment effect (P effect (P fasting metabolic profile and the postprandial concentration of insulin. Women with higher fasting concentrations of leucine and isoleucine and lower fasting concentrations of sphingomyelins and phosphatidylcholines had higher insulin responses despite similar glucose concentration after all kinds of bread (cross-validated ANOVA, P = 0.048). High blood concentration of branched-chain amino acids, i.e., leucine and isoleucine, has been associated with the increased risk of diabetes, which suggests that additional consideration should be given to bread proteins in understanding the beneficial health effects of different kinds of breads. The present study suggests that the fasting metabolic profile can be used to characterize the postprandial insulin demand in individuals with normal glucose metabolism that can be used for establishing strategies for the stratification of individuals in personalized nutrition.

  16. Riparian and Associated Habitat Characteristics Related to Nutrient Concentrations and Biological Responses of Small Streams in Selected Agricultural Areas, United States, 2003-04

    Zelt, Ronald B.; Munn, Mark D.


    Physical factors, including both in-stream and riparian habitat characteristics that limit biomass or otherwise regulate aquatic biological condition, have been identified by previous studies. However, linking the ecological significance of nutrient enrichment to habitat or landscape factors that could allow for improved management of streams has proved to be a challenge in many regions, including agricultural landscapes, where many ecological stressors are strong and the variability among watersheds typically is large. Riparian and associated habitat characteristics were sampled once during 2003-04 for an intensive ecological and nutrients study of small perennial streams in five contrasting agricultural landscapes across the United States to determine how biological communities and ecosystem processes respond to varying levels of nutrient enrichment. Nutrient concentrations were determined in stream water at two different sampling times per site and biological samples were collected once per site near the time of habitat characterization. Data for 141 sampling sites were compiled, representing five study areas, located in parts of the Delmarva Peninsula (Delaware and Maryland), Georgia, Indiana, Ohio, Nebraska, and Washington. This report examines the available data for riparian and associated habitat characteristics to address questions related to study-unit contrasts, spatial scale-related differences, multivariate correlation structure, and bivariate relations between selected habitat characteristics and either stream nutrient conditions or biological responses. Riparian and associated habitat characteristics were summarized and categorized into 22 groups of habitat variables, with 11 groups representing land-use and land-cover characteristics and 11 groups representing other riparian or in-stream habitat characteristics. Principal components analysis was used to identify a reduced set of habitat variables that describe most of the variability among the

  17. Characteristics of a novel polymer gel dosimeter formula for MRI scanning: Dosimetry, toxicity and temporal stability of response.

    Abtahi, S M


    The present study intended to investigate the composition of a new polymer gel dosimeter. The new composition would be more suitable for a wide range of applications in comparison to polyacrylamide gel dosimeter since its extremely toxic acrylamide has been replaced with less harmful monomer i.e. 2-Acrylamido-2-MethylPropane Sulfonic acid (AMPS). To this end, the PAGAT gel dosimeter formula was used as a basis to test the new formulation of polymer gel dosimeter with a different monomer (AMPS) instead of acrylamide by using the %6T and %50C to the formula. The new formulation was named PAMPSGAT (Poly AMPS, Gelatin and THPC) polymer gel dosimeter. Moreover, the MRI response (R2) of dosimeters was analyzed in terms of different dose range as well as post-irradiation time. The results indicated that the dose-response (R2) of AMPS/Bis had a linear trend over a wide dose range. Furthermore, the results showed an acceptable temporal stability for the new polymer gel dosimeter.

  18. The effects of general anaesthesia on nerve-motor response characteristics (rheobase and chronaxie) to peripheral nerve stimulation.

    Tsui, B C


    Using a simple surface nerve stimulation system, I examined the effects of general anaesthesia on rheobase (the minimum current required to stimulate nerve activity) and chronaxie (the minimum time for a stimulus twice the rheobase to elicit nerve activity). Nerve stimulation was used to elicit a motor response from the ulnar nerve at varying pulse widths before and after induction of general anaesthesia. Mean (SD) rheobase before and after general anaesthesia was 0.91 (0.37) mA (95% CI 0.77-1.04 mA) and 1.11 (0.53) mA (95% CI 0.92-1.30 mA), respectively. Mean (SD) chronaxie measured before and after general anaesthesia was 0.32 (0.17) ms (95% CI 0.26-0.38 ms) and 0.29 (0.13) ms (95% CI 0.24-0.33 ms), respectively. Under anaesthesia, rheobase values increased by an average of 20% (p = 0.05), but chronaxie values did not change significantly (p = 0.39). These results suggest that threshold currents used for motor response from nerve stimulation under general anaesthesia might be higher than those used in awake patients.

  19. Genome-wide analysis of Dof transcription factors reveals functional characteristics during development and response to biotic stresses in pepper

    Kang, Won-Hee; Kim, Seungill; Lee, Hyun-Ah; Choi, Doil; Yeom, Seon-In


    The DNA-binding with one zinc finger proteins (Dofs) are a plant-specific family of transcription factors. The Dofs are involved in a variety of biological processes such as phytohormone production, seed development, and environmental adaptation. Dofs have been previously identified in several plants, but not in pepper. We identified 33 putative Dof genes in pepper (CaDofs). To gain an overview of the CaDofs, we analyzed phylogenetic relationships, protein motifs, and evolutionary history. We divided the 33 CaDofs, containing 25 motifs, into four major groups distributed on eight chromosomes. We discovered an expansion of the CaDofs dated to a recent duplication event. Segmental duplication that occurred before the speciation of the Solanaceae lineages was predominant among the CaDofs. The global gene-expression profiling of the CaDofs by RNA-seq analysis showed distinct temporal and pathogen-specific variation during development and response to biotic stresses (two TMV strains, PepMoV, and Phytophthora capsici), suggesting functional diversity among the CaDofs. These results will provide the useful clues into the responses of Dofs in biotic stresses and promote a better understanding of their multiple function in pepper and other species. PMID:27653666

  20. Optimization of the matrix inversion tomosynthesis (MITS) impulse response and modulation transfer function characteristics for chest imaging.

    Godfrey, Devon J; McAdams, H P; Dobbins, James T


    Matrix inversion tomosynthesis (MITS) uses linear systems theory, along with a priori knowledge of the imaging geometry, to deterministically distinguish between true structure and overlying tomographic blur in a set of conventional tomosynthesis planes. In this paper we examine the effect of total scan angle (ANG), number of input projections (N), and plane separation/number of reconstructed planes (NP) on the MITS impulse response (IR) and modulation transfer function (MTF), with the purpose of optimizing MITS imaging of the chest. MITS IR and MTF data were generated by simulating the imaging of a very thin wire, using various combinations of ANG, N, and NP. Actual tomosynthesis data of an anthropomorphic chest phantom were acquired with a prototype experimental system, using the same imaging parameter combinations as those in the simulations. Thoracic projection data from two human subjects were collected for corroboration of the system response analysis in vivo. Results suggest that ANG=20 degrees, N=71, NP=69 is the optimal combination for MITS chest imaging given the inherent constraints of our prototype system. MITS chest data from human subjects demonstrates that the selected imaging strategy can effectively produce high-quality MITS thoracic images in vivo.

  1. Effect of sevoflurane versus propofol-based anesthesia on the hemodynamic response and recovery characteristics in patients undergoing microlaryngeal surgery

    Neerja Bharti


    Full Text Available Background: This randomized study was conducted to compare the hemodynamic changes and emergence characteristics of sevoflurane versus propofol anesthesia for microlaryngeal surgery. Methods: Forty adult patients undergoing microlaryngoscopy were randomly allocated into two groups. In propofol group, anesthesia was induced with 2-3 mg/kg propofol and maintained with propofol infusion 50-200 μg/kg/h. In sevoflurane group induction was carried out with 5-8% sevoflurane and maintained with sevoflurane in nitrous oxide and oxygen. The propofol and sevoflurane concentrations were adjusted to maintain the bispectral index of 40-60. All patients received fentanyl 2 μg/kg before induction and succinylcholine 2 mg/kg to facilitate tracheal intubation. The hemodynamic changes during induction and suspension laryngoscopy were compared. In addition, the emergence time, time to extubation, and recovery were assessed. Results: The changes in heart rate were comparable. The mean arterial pressure was significantly lower after induction and higher at insertion of operating laryngoscope in propofol group as compared to sevoflurane group. More patients in propofol group had episodes of hypotension and hypertension than sevoflurane group. The emergence time, extubation times, and recovery time were similar in both groups. Conclusion: We found that sevoflurane showed advantage over propofol in respect of intraoperative cardiovascular stability without increasing recovery time.

  2. Spatio-temporal characteristics of aerosol distribution over Tibetan Plateau and numerical simulation of radiative forcing and climate response

    李维亮; 于胜民


    In this paper we have analyzed aerosol distribution over the Tibetan Plateau by using the global monthly mean satellite data of Stratospheric Aerosol and Gas Experiment Ⅱ (SAGE Ⅱ).The results are as follows: (1) Stratospheric aerosol optical depth can oscillate in the four seasons. It means that the aerosol optical depth is the thickest in winter and a little thinner in spring and the thinnest in summer and then a little thicker in autumn. We have found that the oscillation is caused by the oscillation of tropopause in different seasons. (2) Stratospheric aerosol comes mainly from sprays of volcano. After eruption of Mount Pinatubo aerosol optical depth in stratosphere over the Tibetan Plateau increases 10 times compared with before. (3) The characteristic of aerosol vertical distribution over the Tibetan Plateau is that there is an extremely high value at the altitude of 70 hPa. The most interesting thing is that the extremely high value can oscillate between 50 hPa and 100 hPa. We have verified that

  3. Mitogenic response and probiotic characteristics of lactic acid bacteria isolated from indigenously pickled vegetables and fermented beverages.

    Kumar, Mukesh; Ghosh, Moushumi; Ganguli, Abhijit


    Lactic acid bacteria from indigenous pickled vegetables and fermented beverages (fermented rice and Madhuca longifolia flowers) were isolated and investigated for their functional characteristics in vitro as potential new probiotic strains. Four isolates (all Lactobacillus spp.) selected on the basis of high tolerance to bile (0.2%) were identified by standard and molecular methods (16S rDNA) as L. helveticus, L. casei, L. delbrueckii and L. bulgaricus from pickled vegetables and fermented beverages respectively. These selected strains had antibiotic resistance, tolerance to artificial gastric juice and phenol (0.4%), enzymatic profile, and antagonistic activity against enteric pathogens (Enterobacter sakazakii, Salmonella typhimurium, Shigella flexneri 2a, Listeria monocytogenes, Yersinia enterocolitica and Aeromonas hydrophila). All strains survived well in artificial gastric juice at low pH (3.0) values for 4 h, possessed bile salt hydrolase activity and were susceptible to most antibiotics including vancomycin. Additionally, the isolates exhibited high tolerance to phenol, high cell surface hydrophobicity (>60%) and induced proliferation of murine splenocytes. All the four strains of present study suppressed the Con A-stimulated proliferation of the mouse spleen cells, although L. casei had the strongest suppressive effect. The results of this study suggest a potential application of the strains (following human clinical trials), for developing probiotic foods.

  4. Response characteristics of a viscoelastic gel under the co-action of sound waves and an electric field

    Tang, Hong; Zhao, Xiaopeng; Wang, Baoxiang; Zhao, Yan


    We design a flexible sound tunable sandwiched panel structure, which is composed of a nanoelectrorheological gel layer and two conductive rubber sheets, and experimentally investigate the tunable behaviors of the sound transmitted through the panel. For the frequency range of 380-500 Hz the transmitted sound pressure level (SPL) decreases with the electric field strength Ee, while at about 550-650 Hz the SPL increases with Ee. Within 500-550 Hz a hump appears and the hump apex shifts in the high frequency direction with increase of Ee. Besides this, the phase angle of the transmitted sound wave changes with Ee within these frequency ranges. The weight fraction of particles in the electrorheological gels also influences these observed tunable characteristics. The theoretical calculation based on a vibration-radiation model agrees with the experimental results, qualitatively. It is revealed that the electric field induced viscoelasticity change in the electrorheological gel and hence the vibration-radiation variation on the sandwiched panel is the origin of the phenomenon. The flexible composite electrorheological panel could be used in sound sensitive artificial skins or sound tunable actuators and has potential for use in robots and intelligent structures and systems.

  5. Sensory response and physical characteristics of gluten-free and gum-free bread with chia flour

    Katira da Mota HUERTA


    Full Text Available Abstract The aim of this study was to evaluate the physical quality and sensory acceptance of gluten-free breads with different percentages of chia flour (Salvia Hispanica L .. The chia flour was used to substitute rice flour and soy flour in order to replace the gum required in this type of bread. Four formulations were developed; a standard made with gum, and three formulations with 2.5%, 5.0% and 7.5% of chia flour. Analyses of specific volume, cooking losses and the rise in dough of the breads were performed. Sensory analysis included tests for affective acceptability and purchase intent. The results showed that the bread with 2.5% chia flour had specific volume and cooking losses similar to the standard. In terms of the rise in dough, the standard showed the highest values, followed by the bread made with 5.0% chia flour. The substitution of soy and rice flour with 2.5% of chia flour produced bread with sensory characteristics similar to the standard in all of the analyzed attributes; it also received higher purchase intent. Using chia flour at a concentration of 2.5%, compared to rice flour and soy flour, proved that it was possible to replace gum in the bread formulation.

  6. Effects of medium-chain fatty acids on performance, carcass characteristics, blood biochemical parameters and immune response in Japanese quail.

    Saeidi, E; Shokrollahi, B; Karimi, K; Amiri-Andi, M


    This study had the aim of evaluating the effects of medium-chain fatty acids (MCFA) on performance, carcass characteristics, some blood parameters and antibody titre against sheep red blood cells (SRBC) in quail. A total of 240 quail chicks were allotted to 4 treatments consisting of respectively 0, 1, 2 and 4 g/kg dietary MCFA. There were no significant differences in body weight, feed intake and feed conversion ratio among treatments at different stages of the experiment. MCFAs had no significant effect on breast, thigh, liver, spleen and bursa of Fabricius weight ratios. However, the relative weight of abdominal fat significantly decreased in quail receiving 0.2 and 0.4 MCFA as compared to other treatments. Concentrations of low-density lipoprotein-cholesterol (LDL), triglycerides and total cholesterol were decreased and high-density lipoprotein (HDL)-cholesterol was increased in quail chicks receiving MCFA compared with control quail chicks. The concentrations of SRBC antibody were not statistically different among treatments. It is concluded that MCFA significantly decreased LDL, triglycerides, cholesterol and abdominal fat and increased HDL in quail chicks.

  7. Dynamic characteristics of laser Doppler flowmetry signals obtained in response to a local and progressive pressure applied on diabetic and healthy subjects

    Humeau, Anne; Koitka, Audrey; Abraham, Pierre; Saumet, Jean-Louis; L'Huillier, Jean-Pierre


    In the biomedical field, the laser Doppler flowmetry (LDF) technique is a non-invasive method to monitor skin perfusion. On the skin of healthy humans, LDF signals present a significant transient increase in response to a local and progressive pressure application. This vasodilatory reflex response may have important implications for cutaneous pathologies involved in various neurological diseases and in the pathophysiology of decubitus ulcers. The present work analyses the dynamic characteristics of these signals on young type 1 diabetic patients, and on healthy age-matched subjects. To obtain accurate dynamic characteristic values, a de-noising wavelet-based algorithm is first applied to LDF signals. All the de-noised signals are then normalised to the same value. The blood flow peak and the time to reach this peak are then calculated on each computed signal. The results show that a large vasodilation is present on signals of healthy subjects. The mean peak occurs at a pressure of 3.2 kPa approximately. However, a vasodilation of limited amplitude appears on type 1 diabetic patients. The maximum value is visualised, on the average, when the pressure is 1.1 kPa. The inability for diabetic patients to increase largely their cutaneous blood flow may bring explanations to foot ulcers.

  8. Dynamic characteristics of the cutaneous vasodilator response to a local external pressure application detected by the laser Doppler flowmetry technique on anesthetized rats

    Humeau, Anne; Koitka, Audrey; Saumet, Jean-Louis; L'Huillier, Jean-Pierre


    The laser Doppler flowmetry technique has recently been used to report a significant transient increase of the cutaneous blood flow signal when a local non-noxious pressure is applied progressively on the skin (11.1 Pa/s). The present work analyses the dynamic characteristics of this vasodilatory reflex response on anaesthetised rats. A de-noising algorithm using wavelets is proposed to obtain accurate values of these dynamic characteristics. The blood flow peak and the time to reach this peak are computed on the de-noised recordings. The results show that the mean time to reach the peak of perfusion is 85.3 s (time t = 0 at the beginning of the pressure application). The mean peak value is 188.3 arbitrary units (a.u.), whereas the mean value of the perfusion before the pressure application is 113.4 a.u. The mean minimum value obtained at the end of the experiment is 60.7 a.u. This latter value is, on the average, reached 841.3 s after the beginning of the pressure application. The comparison of the dynamic characteristics, computed with the de-noising algorithm on signals obtained in other situations, will give a better understanding on some cutaneous lesions such as those present on diabetic people.

  9. Expression of zinc and cadmium responsive genes in leaves of willow (Salix caprea L.) genotypes with different accumulation characteristics.

    Konlechner, Cornelia; Türktaş, Mine; Langer, Ingrid; Vaculík, Marek; Wenzel, Walter W; Puschenreiter, Markus; Hauser, Marie-Theres


    Salix caprea is well suited for phytoextraction strategies. In a previous survey we showed that genetically distinct S. caprea plants isolated from metal-polluted and unpolluted sites differed in their zinc (Zn) and cadmium (Cd) tolerance and accumulation abilities. To determine the molecular basis of this difference we examined putative homologues of genes involved in heavy metal responses and identified over 200 new candidates with a suppression subtractive hybridization (SSH) screen. Quantitative expression analyses of 20 genes in leaves revealed that some metallothioneins and cell wall modifying genes were induced irrespective of the genotype's origin and metal uptake capacity while a cysteine biosynthesis gene was expressed constitutively higher in the metallicolous genotype. The third and largest group of genes was only induced in the metallicolous genotype. These data demonstrate that naturally adapted woody non-model species can help to discover potential novel molecular mechanisms for metal accumulation and tolerance.

  10. Characteristics and stability of slope movement response to underground mining of shallow coal seams away from gullies

    Zhang Dongsheng; Fan Gangwei; Wang Xufeng


    Underground pressure is abnormal during mining of shallow coal seams under gullies.We studied gully slope movements,subject to underground mining,with physical simulation and theoretical analysis.The rules disclose that the slope rock slides horizontally in response to mining in the direction of gullies and rotates reversely with the appearance of a polygon block in mining away from gullies.We focused our attention on the case of mining away from a gully.We built a mechanical model in terms of a polygon block hinged structure and investigated the variation of horizontal thrust and shear force at the hinged point in relation to the rotation angle under different fragmentations.The Sliding-Rotation instability conditions of the polygon block hinged structure are presented based on the analyses of sliding instability and rotation instability.These results can serve as a theoretical guide for roof control during mining away from gullies in a coalfield defined by gullies.

  11. Dose-response characteristics of methylphenidate on locomotor behavior and on sensory evoked potentials recorded from the VTA, NAc, and PFC in freely behaving rats

    Swann Alan C


    Full Text Available Abstract Background Methylphenidate (MPD is a psychostimulant commonly prescribed for attention deficit/hyperactivity disorder. The mode of action of the brain circuitry responsible for initiating the animals' behavior in response to psychostimulants is not well understood. There is some evidence that psychostimulants activate the ventral tegmental area (VTA, nucleus accumbens (NAc, and prefrontal cortex (PFC. Methods The present study was designed to investigate the acute dose-response of MPD (0.6, 2.5, and 10.0 mg/kg on locomotor behavior and sensory evoked potentials recorded from the VTA, NAc, and PFC in freely behaving rats previously implanted with permanent electrodes. For locomotor behavior, adult male Wistar-Kyoto (WKY; n = 39 rats were given saline on experimental day 1 and either saline or an acute injection of MPD (0.6, 2.5, or 10.0 mg/kg, i.p. on experimental day 2. Locomotor activity was recorded for 2-h post injection on both days using an automated, computerized activity monitoring system. Electrophysiological recordings were also performed in the adult male WKY rats (n = 10. Five to seven days after the rats had recovered from the implantation of electrodes, each rat was placed in a sound-insulated, electrophysiological test chamber where its sensory evoked field potentials were recorded before and after saline and 0.6, 2.5, and 10.0 mg/kg MPD injection. Time interval between injections was 90 min. Results Results showed an increase in locomotion with dose-response characteristics, while a dose-response decrease in amplitude of the components of sensory evoked field responses of the VTA, NAc, and PFC neurons. For example, the P3 component of the sensory evoked field response of the VTA decreased by 19.8% ± 7.4% from baseline after treatment of 0.6 mg/kg MPD, 37.8% ± 5.9% after 2.5 mg/kg MPD, and 56.5% ± 3.9% after 10 mg/kg MPD. Greater attenuation from baseline was observed in the NAc and PFC. Differences in the intensity of

  12. Analysis of MMC-HVDC Transient Response Characteristic Under Typical Disturbances%MMC-HVDC典型扰动暂态响应特性分析

    马雅青; 王卫安; 张杰; 唐剑钊; 任涛


    为揭示具有新型拓扑结构的基于模块化多电平换流器直流输电系统MMC-HVDC(modular multilevel converter high voltage direct current)的电磁暂态特性,对该系统进行典型扰动暂态响应的特性分析根据MMC拓扑结构,推导了交流电网不平衡时的MMC交流侧电磁暂态模型,并基于模型设计了正、负序双内环电流控制和外环功率控制的控制策略.同时,对MMC-HVDC在各种典型扰动下的暂态响应特性进行了详细的仿真分析,仿真结果表明所设计的控制策略的正确性.MMC-HVDC在遭受各种典型扰动时具有良好的暂态响应特性,并能稳定、充裕地运行.%In order to reveal the electromagnetic transient characteristics of new topology structure MMC is necessary to study the transient response characteristics of the new HVDC under various typical disturbances. According to the topology structure of MMCthe electromagnetic transient model of AC side of MMC was derived under the condition of unbalance AC grid. The control strategies with inneer loops current control of positive and negative sequence and an outer loop's power control were designed. With various typical disturbances simulations,the transient response of MMC-HVDC was designed. With various typical disturb ances simulations,the transient response of MMC-HVDC was studied and the correctness of the proposed con trol strategy was confirmed. MMC-HVDC has good transient response characteristics, and can operate stably and fully under various typical disturbances.

  13. Response of soil organic layer characteristics to different amounts of logging residue in a Scots pine thinning stand

    Smolander, Aino; Kitunen, Veikko; Tamminen, Pekka; Kukkola, Mikko


    Since there is an increasing demand for production of bioenergy, forest management using logging residue from both clear-cutting and thinning stands is becoming more common. Therefore there is a need of information how this whole-tree harvest, as compared to the traditional stem-only harvest, changes forest soil characteristics in long-term. The aim of this study was to investigate the effects of logging residue removal on soil microbial processes related to C and N cycling and on two major groups of plant secondary compounds, phenolic compounds and terpenes. These two groups of compounds were of interest since logging residue contains the highest proportion of most of these compounds. In addition, certain phenolic compounds and terpenes have been shown to regulate N transformations in forests soils. The study site was a young Scots pine stand in central Finland. It was thinned and four different amounts of logging residue, consisting of needles and tree branches, were distributed around a tree: 0, 40, 80 and 120 kg of fresh logging residue on a circle (diameter 2.5 m) around a tree. Samples were taken from the organic layer (F+H) four years after the treatment. Two highest amounts of logging residue increased both C and net N mineralization and glucose-induced respiration, but the amount of logging residue did not affect microbial biomass C or N. There were not any large differences between the treatments in the concentrations of mono, sesqui-, di- or triterpenes, although some terpenes showed an increase with the highest amount of residues. Amount of logging residue did not clearly affect the concentrations of volatile monoterpenes in soil atmosphere.

  14. Responses of sensitive and tolerant bush beans (Phaseolus vulgaris L.) to ozone in open-top chambers are influenced by phenotypic differences, morphological characteristics, and the chamber environment

    Elagoez, Vahram [Plant Biology Graduate Program, University of Massachusetts, Amherst, MA 01003 (United States)]. E-mail:; Manning, William J. [Department of Plant, Soil and Insect Sciences, University of Massachusetts, Amherst, MA 01003 (United States)


    Responses of bush bean (Phaseolus vulgaris L.) lines 'S156' (O{sub 3}-sensitive) and 'R123' (O{sub 3}-tolerant), and cultivars 'BBL 290' (O{sub 3}-sensitive) and 'BBL 274' (O{sub 3}-tolerant) to ambient ozone (O{sub 3}) were investigated during the 2001 and 2002 growing seasons. Seedlings were grown in pots inside open-top chambers (OTCs), with charcoal filtered (CF) and non-filtered (NF) ambient air, and in non-chambered ambient air (AA) plots. Growth parameters from individual plants were evaluated after harvests at the end of vegetative (V{sub 4}) and reproductive (R{sub 10}) growth phases. Results at V{sub 4} indicated that CF did not provide additional benefits over NF in 'S156' in 2001 and 2002. In contrast, exposure to CF significantly impaired the growth of 'R123'. At the end of R{sub 10}, 'S156' produced more pods, most of which remained immature, and contained fewer seeds or were more frequently aborted, whereas pods produced in 'R123' reached pod maturation and senescence more consistently. Despite increased seed weights inside the OTCs, as observed in 'S156', differences between the two lines were insignificant when grown outside OTCs. Results from the 'BBL 290'/'BBL 274' pair, especially at V{sub 4} phase, remained inconclusive. Plant morphological characteristics, variabilities in environmental conditions, and 'chamber effects' inside OTCs were influential in determining plant response to ambient O{sub 3}. - Phenotypic differences, morphological characteristics, and 'chamber effects' inside OTCs are equally influential in determining the responses of beans to O{sub 3}.

  15. Simulating and validating the stress-strain curve of the matrix cracking of ceramic matrix composite%考虑基体开裂的陶瓷基复合材料应力-应变曲线模拟方法及验证

    孙志刚; 苗艳; 宋迎东


    提出了蒙特卡罗方法模拟陶瓷基复合材料基体随机开裂过程,采用剪滞模型描述了复合材料出现损伤时细观应力场,并推导得到了考虑基体开裂时复合材料拉伸应力-应变曲线计算公式.开展了室温环境下C/SiC复合材料的单轴拉伸试验,并将理论预测应力-应变曲线与试验结果进行对比.同时,采用该方法对SiC/CAS,SiC/Si3N4复合材料应力-应变曲线进行了模拟,并与国外提供的相关试验数据进行比较,发现两者吻合得较好,从而证实了蒙特卡罗法可有效地模拟考虑基体随机开裂过程的陶瓷基复合材料应力-应变曲线.此外,还分析了Weibull模量、残余热应力和初始开裂应力对应力-应变曲线的影响.研究表明:Weibull模量越大,应力-应变曲线非线性越明显;热残余应力越大,应力-应变曲线偏转越早,非线性越明显;初始开裂应力与Weibull模量对应力-应变曲线影响规律相似.%The matrix random cracking of ceramic matrix composite was simulated by Montel Carlo model.The shear-lag model was used to analyze the micro-stress field of the damaged composites,and the formula of the stress-strain behavior was derived.The uniaxial tensile experiment of unidirectional-C/SiC composites at ambient temperature has been performed,and the simulated stress-strain curve was compared to the experimental data.The tensile stress-strain curves of SiC/CAS and SiC/Si3N4 composites were simulated,which agreed well with the related experimental results.Besides,infuence of the model parameters on stress-strain curve was analyzed.Research shows that the higher the Weibull modulus,the more evident the non-linear phenomenon;the higher the thermal residual stress,the earlier the non-linear phenomenon appears;the effect of the minimum cracking stress on the stress-strain is similar to the effect of the Weibull modulus;the Monte Carlo model can simulate the stress-strain curve of ceramic matrix composites

  16. Heterogeneity of left ventricular signal characteristics in response to acute vagal stimulation during ventricular fibrillation in dogs.

    Nazeri, Alireza; Elayda, MacArthur A; Dragnev, Lubomir; Frank, Christopher M; Qu, Jihong; Afonso, Valtino X; Rasekh, Abdi; Saeed, Mohammad; Cheng, Jie; Shuraih, Mossaab; Massumi, Ali; Razavi, Mehdi


    Studies have shown that long-term vagal stimulation is protective against ventricular fibrillation; however, the effects of acute vagal stimulation during ventricular fibrillation in the normal heart have not been investigated. We examined the effects of acute vagal stimulation on ventricular fibrillation in a canine model. In 4 dogs, we induced 30-second periods of ventricular fibrillation by means of intraventricular pacing. During 2 of the 4 periods of fibrillation that we analyzed, vagal stimulation was delivered through electrodes in the caudal ends of the vagus nerves. Noncontact unipolar electrograms were recorded from 3 ventricular regions: the basal septum, apical septum, and lateral free wall. We then computed the most frequent cycle length, mean organization index, and mean electrogram amplitude for each region. During fibrillation, vagal stimulation shortened the most frequent cycle lengths in the basal septum (P=0.02) and apical septum (P=0.0001), but not in the lateral wall (P=0.46). In addition, vagal stimulation significantly reduced the mean organization indices in the apical septum (P ventricular fibrillation in canine myocardium in a spatially heterogeneous manner. This nonuniformity of response may have implications with regard to manipulating the autonomic system as a means of modifying the substrate for ventricular dysrhythmias.

  17. Shallow shear-wave velocity profiles and site response characteristics from microtremor array measurements in Metro Manila, the Philippines

    Grutas, Rhommel; Yamanaka, Hiroaki


    This paper presents the outcome of reconnaissance surveys in metropolitan Manila (Metro Manilla), the Philippines, with the aim of mapping shallow shear-wave velocity structures. Metro Manila is a seismically active and densely populated region that is in need of detailed investigation of the subsurface structures, to assess local site effects in seismic hazard estimation. We conducted microtremor array observations and used the spatial autocorrelation method to estimate the shear-wave profiles at 32 sites in major geological settings in Metro Manila. We applied a hybrid genetic simulated annealing algorithm to invert phase velocity data from the spatial autocorrelation method to generate shear-wave velocity models near the global best-fit solution. The comparison between the inferred shear-wave velocity profiles and PS logging showed good agreement in terms of the fundamental mode of Rayleigh waves and site responses. Then, we utilised the inferred shear-wave velocity profiles to compute the site amplifications with reference to the motion in engineering bedrock. Subsequently, the site amplifications have been grouped, based on NEHRP site classes. The amplification factor has also been compared with the average shear-wave velocity of the upper 30m at each site, to produce a power-law regression equation that can be used as a starting basis for further site-effects evaluation in the metropolis.

  18. Application of response surface methodology for studying the product characteristics of extruded rice-cowpea-groundnut blends.

    Asare, Emmanuel Kwasi; Sefa-Dedeh, Samuel; Sakyi-Dawson, Esther; Afoakwa, Emmanuel Ohene


    Response surface methodology (with central composite rotatable design for k=3) was used to investigate the product properties of extruded rice-cowpea-groundnut blends in a single screw extruder. The combined effect of cowpea (0-20%), groundnut (0-10%), and feed moisture (14-48%) levels were used for formulation of the products. The product moisture, expansion ratio, bulk density and total colour change were studied using standard analytical methods. Well-expanded rice-legume blend extrudates of less bulk density and lower moisture content were produced at low feed moisture. Increasing legume addition affected the various shades of colour in the product. Models developed for the indices gave R(2) values ranging from 52.8% (for the b-value) to 86.5% (for bulk density). The models developed suggested that the optimal process variables for the production of a puffed snack with an enhanced nutrition and spongy structure from a rice-cowpea-groundnut blend are low feed moisture of 14-20% and maximum additions of 20% cowpea and 10% groundnut. A lack-of-fit test showed no significance, indicating that the models adequately fitted the data.

  19. Core Cross-Linked Multiarm Star Polymers with Aggregation-Induced Emission and Temperature Responsive Fluorescence Characteristics

    Zhang, Zhen


    Aggregation-induced emission (AIE) active core cross-linked multiarm star polymers, carrying polystyrene (PS), polyethylene (PE), or polyethylene-b-polycaprolactone (PE-b-PCL) arms, have been synthesized through an “arm-first” strategy, by atom transfer radical copolymerization (ATRP) of a double styrene-functionalized tetraphenylethene (TPE-2St) used as a cross-linker with linear arm precursors possessing terminal ATRP initiating moieties. Polyethylene macroinitiator (PE–Br) was prepared via the polyhomologation of dimethylsulfoxonium methylide with triethylborane followed by oxidation/hydrolysis and esterification of the produced PE–OH with 2-bromoisobutyryl bromide; polyethylene-block-poly(ε-caprolactone) diblock macroinitiator was derived by combining polyhomologation with ring-opening polymerization (ROP). All synthesized star polymers showed AIE-behavior either in solution or in bulk. At high concentration in good solvents (e.g., THF, or toluene) they exhibited low photoluminescence (PL) intensity due to the inner filter effect. In sharp contrast to the small molecule TPE-2St, the star polymers were highly emissive in dilute THF solutions. This can be attributed to the cross-linked structure of poly(TPE-2St) core which restricts the intramolecular rotation and thus induces emission. In addition, the PL intensity of PE star polymers in THF(solvent)/n-hexane(nonsolvent) mixtures, due to their nearly spherical shape, increased when the temperature decreased from 55 to 5 °C with a linear response in the range 40–5 °C.

  20. Effect of inulin on textural and sensory characteristics of sorghum based high fibre biscuits using response surface methodology.

    Banerjee, Chandralekha; Singh, Rakhi; Jha, Alok; Mitra, Jayeeta


    Five blends of sorghum (Sorghum bicolor) flour (25.0-45.0 %) and whole wheat flour were used to make biscuits using inulin (5.0-10.0 %) and guar gum (1.0-2.0 %). An experimental investigation was carried out with the aim of evaluating the effect of fat replacer (inulin) and sorghum flour on the quality of high fibre and low calorie biscuits. For this purpose, the biscuit dough and the biscuit samples were analyzed. The analysis was based on hardness of the dough, hardness of the biscuit, fracturability and overall acceptability (OAA) scores. Results showed that increasing the amount of sorghum flour in biscuit increased the dough hardness and biscuit hardness, whereas, biscuit fracturability decreased and OAA scores increased up to the level at which sorghum flour ranged from 35.0 to 40.0 % after which it decreased. An increase in the amount of inulin was followed by an increase in biscuit hardness, while, fracturability and OAA scores decreased and there was little effect on the dough hardness. Optimum conditions generated from the analysis was 40.8 % sorghum flour, 6.5 % inulin and 1.0 % guar gum. The predicted response in terms of dough hardness, fracturability, biscuit hardness and OAA were 212.4 g, 36.4 mm, 4.8 kg and 7.06, respectively. The desirability of the optimum condition was 0.827.