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Sample records for contact problems current

  1. [Current contact allergens].

    PubMed

    Geier, J; Uter, W; Lessmann, H; Schnuch, A

    2011-10-01

    Ever-changing exposure to contact allergens, partly due to statutory directives (e.g. nickel, chromate, methyldibromo glutaronitrile) or recommendations from industrial associations (e.g. hydroxyisohexyl 3-cyclohexene carboxaldehyde), requires on-going epidemiologic surveillance of contact allergy. In this paper, the current state with special focus in fragrances and preservatives is described on the basis of data of the Information Network of Departments of Dermatology (IVDK) of the year 2010. In 2010, 12,574 patients were patch tested in the dermatology departments belonging to the IVDK. Nickel is still the most frequent contact allergen. However the continuously improved EU nickel directive already has some beneficial effect; sensitization frequency in young women is dropping. In Germany, chromate-reduced cement has been in use now for several years, leading to a decline in chromate sensitization in brick-layers. Two fragrance mixes are part of the German baseline series; they are still relevant. The most important fragrances in these mixes still are oak moss absolute and hydroxyisohexyl 3-cyclohexene carboxaldehyde. However, in relation to these leading allergens, sensitization frequency to other fragrances contained in the mixes seems to be increasing. Among the preservatives, MCI/MI has not lost its importance as contact allergen, in contrast to MDBGN. Sources of MCI/MI sensitization obviously are increasingly found in occupational context. Methylisothiazolinone is a significant allergen in occupational settings, and less frequently in body care products.

  2. Determining a Surrogate Contact Pair in a Hertzian Contact Problem.

    PubMed

    Sanders, Anthony P; Brannon, Rebecca M

    2011-04-01

    Laboratory testing of contact phenomena can be prohibitively expensive if the interacting bodies are geometrically complicated. This work demonstrates means to mitigate such problems by exploiting the established observation that two geometrically dissimilar contact pairs may exhibit the same contact mechanics. Specific formulas are derived that allow a complicated Hertzian contact pair to be replaced with an inexpensively manufactured and more easily fixtured surrogate pair, consisting of a plane and a spheroid, which has the same (to second-order accuracy) contact area and pressure distribution as the original complicated geometry. This observation is elucidated by using direct tensor notation to review a key assertion in Hertzian theory; namely, geometrically complicated contacting surfaces can be described to second-order accuracy as contacting ellipsoids. The surrogate spheroid geometry is found via spectral decomposition of the original pair's combined Hessian tensor. Some numerical examples using free-form surfaces illustrate the theory, and a laboratory test validates the theory under a common scenario of normally compressed convex surfaces. This theory for a Hertzian contact substitution may be useful in simplifying the contact, wear, or impact testing of complicated components or of their constituent materials.

  3. Contact Pressure and Shear Stress Analysis on Conforming Contact Problem

    NASA Astrophysics Data System (ADS)

    Nagatani, Haruo; Imou, Akitoshi

    Two methods to solve a conforming contact problem are proposed. First method is general and can be applicable to the contact case between elastic arbitrary shape bodies. For verification FEA is performed on the convex-concave sphere contact, and the result of this method is well corresponding to the FEA result. However, the accuracy deteriorates when the mesh aspect ratio is extremely large. This phenomenon is caused by the usage of numerical integration for the calculation of influence coefficient. The second method is devised to avoid this problem, while this improved method is applicable only to the case when the contact area can be considered to be on a cylinder surface. By using this method, the contact pressure can be obtained without the deterioration even in the case of edge load occurring between ball bearing race shoulder and ball. The results of the contact pressure and the shear stress that is necessary for bearing life estimation are compared with the FEA result, which showed well correspondence.

  4. On contact problems of elasticity theory

    NASA Technical Reports Server (NTRS)

    Kalandiya, A. I.

    1986-01-01

    Certain contact problems are reviewed in the two-dimensional theory of elasticity when round bodies touch without friction along most of the boundary and, therefore, Herz' hypothesis on the smallness of the contact area cannot be used. Fundamental equations were derived coinciding externally with the equation in the theory of a finite-span wing with unkown parameter. These equations are solved using Multhopp's well-known technique, and numerical calculations are performed in specific examples.

  5. Current Social Problem Novels.

    ERIC Educational Resources Information Center

    Kenney, Donald J.

    This review of social problem novels for young adults opens with a brief background of the genre, then lists the dominant themes of social problem fiction and nonfiction novels that have been published in the last two years, such as alcoholism, alienation, death, growing up and self-awarness, drugs, and divorce. Other themes mentioned are…

  6. Acoustoelectric Current in Suspended Quantum Point Contacts

    NASA Astrophysics Data System (ADS)

    Kreft, Dustin J.

    Here, I present a detailed analysis and discussion of acoustoelectric current and the behavior of said current under the influence of a magnetic field and its interactions with quantum point contacts (QPCs). The QPCs lie on a suspended nano-bridge, which acts as an acoustic waveguide, allowing a stronger electron-phonon coupling; and hence, a larger acoustoelectric current with amplified conductance effects at a high temperature of 4.2 K. The acoustoelectric current is first studied under the influence of a perpendicular magnetic field. Through this measurement a theoretical model was developed to accurately describe and reproduce the measurement trend; showing how the acoustoelectric current is strongly dependent on the surface acoustic wave (SAW) attenuation and the two dimensional electron gas (2DEG) conductance changes under such conditions. The next set of measurements focus on the acoustoelectric current and its interactions with the potential created by applying a negative bias to the QPCs. Here, the electronically confined region gives rise to enhanced electron-phonon interactions which manifest themselves as a change in acoustoelectric current polarity, due to phonon back scattering, and enhanced oscillations in the measured current due to subband depopulation and the change in the potential landscape. Further information is provided such as fabrication steps, theoretical background on QPCs and SAWs, additional information of SAW-QPC interactions under the influence of a magnetic field, and phase locked acoustoelectric current with QPC pinch off.

  7. RACIAL CONTACT, PERSONALITY, AND GROUP PROBLEM SOLVING.

    ERIC Educational Resources Information Center

    ABNER, EDWARD V.; LEWIT, DAVID W.

    THIS STUDY TESTS THE HYPOTHESIS THAT BIRACIAL GROUPS IN WHICH RACEMATES WERE PAIRED FOR DIRECT CONTACT WOULD PERFORM BETTER THAN THOSE IN WHICH RACEMATES WERE ISOLATED. IT ALSO ASSUMED THAT ETHNOCENTRIC SUBJECTS WOULD PERFORM BETTER WITH CONTACT WITH A RACEMATE, AND THAT AGGRESSIVE SUBJECTS WOULD GET ALONG WELL WITHOUT IT. THE SUBJECTS WERE BOYS…

  8. Reduction technique for tire contact problems

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Peters, Jeanne M.

    1995-01-01

    A reduction technique and a computational procedure are presented for predicting the tire contact response and evaluating the sensitivity coefficients of the different response quantities. The sensitivity coefficients measure the sensitivity of the contact response to variations in the geometric and material parameters of the tire. The tire is modeled using a two-dimensional laminated anisotropic shell theory with the effects of variation in geometric and material parameters, transverse shear deformation, and geometric nonlinearities included. The contact conditions are incorporated into the formulation by using a perturbed Lagrangian approach with the fundamental unknowns consisting of the stress resultants, the generalized displacements, and the Lagrange multipliers associated with the contact conditions. The elemental arrays are obtained by using a modified two-field, mixed variational principle. For the application of the reduction technique, the tire finite element model is partitioned into two regions. The first region consists of the nodes that are likely to come in contact with the pavement, and the second region includes all the remaining nodes. The reduction technique is used to significantly reduce the degrees of freedom in the second region. The effectiveness of the computational procedure is demonstrated by a numerical example of the frictionless contact response of the space shuttle nose-gear tire, inflated and pressed against a rigid flat surface.

  9. Stability problems in point contact solar cells

    NASA Astrophysics Data System (ADS)

    Gruenbaum, P. E.; Sinton, R. A.; Swanson, R. M.

    Single-crystal silicon point-contact solar cells show a degradation in their efficiency after being exposed to concentrated sunlight. Two mechanisms appear to be responsible: an increase in surface recombination velocity caused by ultraviolet light, possibly due to electron injection from the silicon into the oxide, and a gradual lowering of the effective carrier lifetime that occurs when the cell is under high-level injection for an extended period of time. Point-contact solar cells whose front-side passivation has a phosphorus as well as a thermal oxide diffusion are dramatically more resistant to ultraviolet radiation damage. Modeling results indicate that it is possible to make a point-contact solar cell that is 26.8 percent efficient after massive ultraviolet exposure.

  10. Shape optimization for contact problems based on isogeometric analysis

    NASA Astrophysics Data System (ADS)

    Horn, Benjamin; Ulbrich, Stefan

    2016-08-01

    We consider the shape optimization for mechanical connectors. To avoid the gap between the representation in CAD systems and the finite element simulation used by mathematical optimization, we choose an isogeometric approach for the solution of the contact problem within the optimization method. This leads to a shape optimization problem governed by an elastic contact problem. We handle the contact conditions using the mortar method and solve the resulting contact problem with a semismooth Newton method. The optimization problem is nonconvex and nonsmooth due to the contact conditions. To reduce the number of simulations, we use a derivative based optimization method. With the adjoint approach the design derivatives can be calculated efficiently. The resulting optimization problem is solved with a modified Bundle Trust Region algorithm.

  11. Non-contact current and voltage sensor

    SciTech Connect

    Carpenter, Gary D; El-Essawy, Wael; Ferreira, Alexandre Peixoto; Keller, Thomas Walter; Rubio, Juan C; Schappert, Michael A

    2014-03-25

    A detachable current and voltage sensor provides an isolated and convenient device to measure current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing that contains the current and voltage sensors, which may be a ferrite cylinder with a hall effect sensor disposed in a gap along the circumference to measure current, or alternative a winding provided through the cylinder along its axis and a capacitive plate or wire disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.

  12. Mechanisms of current flow in metal-semiconductor ohmic contacts

    SciTech Connect

    Blank, T. V. Gol'dberg, Yu. A.

    2007-11-15

    Published data on the properties of metal-semiconductor ohmic contacts and mechanisms of current flow in these contacts (thermionic emission, field emission, thermal-field emission, and also current flow through metal shunts) are reviewed. Theoretical dependences of the resistance of an ohmic contact on temperature and the charge-carrier concentration in a semiconductor were compared with experimental data on ohmic contacts to II-VI semiconductors (ZnSe, ZnO), III-V semiconductors (GaN, AlN, InN, GaAs, GaP, InP), Group IV semiconductors (SiC, diamond), and alloys of these semiconductors. In ohmic contacts based on lightly doped semiconductors, the main mechanism of current flow is thermionic emission with the metal-semiconductor potential barrier height equal to 0.1-0.2 eV. In ohmic contacts based on heavily doped semiconductors, the current flow is effected owing to the field emission, while the metal-semiconductor potential barrier height is equal to 0.3-0.5 eV. In alloyed In contacts to GaP and GaN, a mechanism of current flow that is not characteristic of Schottky diodes (current flow through metal shunts formed by deposition of metal atoms onto dislocations or other imperfections in semiconductors) is observed.

  13. New contact measures for the protein docking problem

    SciTech Connect

    Lenhof, H.P.

    1997-12-01

    We have developed and implemented a parallel distributed algorithm for the rigid-body protein docking problem. The algorithm is based on a new fitness function for evaluating the surface matching of a given conformation. The fitness function is defined as the weighted sum of two contact measures, the geometric contact measure and the chemical contact measure. The geometric contact measure measures the {open_quotes}size{close_quotes} of the contact area of two molecules. It is a potential function that counts the {open_quotes}van der Waals contacts{close_quotes} between the atoms of the two molecules (the algorithm does not compute the Lennard-Jones potential). The chemical contact measure is also based on the {open_quotes}van der Waals contacts{close_quotes} principle: We consider all atoms pairs that have a {open_quotes}van der Waals{close_quotes} contact, but instead of adding a constant for each pair (a, b), we add a {open_quotes}chemical weight{close_quotes} that depends on the atom pair (a, b). We tested our docking algorithm with a test set that contains the test examples of Norel et al. and Fischer et al. and compared the results of our docking algorithm with the results of Norel et al., Fischer et al. and Meyer et al. In 32 of 35 test examples the best conformation with respect to the fitness function was an approximation of the real conformation. 37 refs., 6 figs., 4 tabs.

  14. The treatment of contact problems as a non-linear complementarity problem

    SciTech Connect

    Bjorkman, G.

    1994-12-31

    Contact and friction problems are of great importance in many engineering applications, for example in ball bearings, bolted joints, metal forming and also car crashes. In these problems the behavior on the contact surface has a great influence on the overall behavior of the structure. Often problems such as wear and initiation of cracks occur on the contact surface. Contact problems are often described using complementarity conditions, w {>=} 0, p {>=} 0, w{sup T}p = 0, which for example represents the following behavior: (i) two bodies can not penetrate each other, i.e. the gap must be greater than or equal to zero, (ii) the contact pressure is positive and different from zero only if the two bodies are in contact with each other. Here it is shown that by using the theory of non-linear complementarity problems the unilateral behavior of the problem can be treated in a straightforward way. It is shown how solution methods for discretized frictionless contact problem can be formulated. By formulating the problem either as a generalized equation or as a B-differentiable function, it is pointed out how Newton`s method may be extended to contact problems. Also an algorithm for tracing the equilibrium path of frictionless contact problems is described. It is shown that, in addition to the {open_quotes}classical{close_quotes} bifurcation and limit points, there can be points where the equilibrium path has reached an end point or points where bifurcation is possible even if the stiffness matrix is non-singular.

  15. Method and apparatus for producing co-current fluid contact

    DOEpatents

    Trutna, William R.

    1997-01-01

    An improved packing system and method are disclosed wherein a packing section includes a liquid distributor and a separator placed above the distributor so that gas rising through the liquid distributor contacts liquid in the distributor, forming a gas-liquid combination which rises in co-current flow to the separator. Liquid is collected in the separator, from which gas rises.

  16. CdS-metal contact at higher current densities.

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.; Boeer, K. W.; Dussel, G. A.

    1973-01-01

    An investigation is conducted concerning the mechanisms by which a steady flow of current proceeds through the contact when an external voltage is applied. The main characteristics of current mechanisms are examined, giving attention to photoemission from the cathode, thermionic emission, minority-carrier extraction, and the tunneling of electrons. A high-field domain analysis is conducted together with experimental studies. Particular attention is given to the range in which tunneling predominates.

  17. [Occupational asthma: current state of the problem].

    PubMed

    Bousová, Karin

    2004-01-01

    Occupational asthma is a disease with serious medical, social and economical consequences. Most patients have to change their jobs and very often they lose their professional qualification. This article gives a current review of the problems of occupational bronchial asthma and allergic rhinitis in the region of Eastern Bohemia. The results obtained are compared with the situation in the whole Czech Republic and in the world. The number of new cases of occupational asthma and allergic rhinitis discovered in the contact area of the Department of Occupational Medicine at the University Hospital in Hradec Králové fluctuates around 15-20 cases per year, and 80-100 new cases are reported in the whole republic. The rate of occupational asthma and occupational allergic rhinitis of the total asthma and rhinitis incidence in the Czech population fluctuates between 5-15%. Regarding the number of affected employees, flour is considered the most important allergen. Other important noxas include agricultural allergens, textile dust, diisocyanates and disinfectious preparations. The importance of the alergogenius effect of natural rubber latex and diisocyanates has increased in occupational medicine mainly in the last 20 years. Regarding latex, its harmful effect has been especially demonstrated in health providers who wear protective latex gloves, which results not only in contact eczema-dermatitis, but also in bronchial asthma and allergic rhinitis. Diisocyanates, highly reactive and aggressive substances, originate during polyurethane production which has a wide industrial application (production of polyurethane foam and rubber, paints, adhesives, injected substances, glues, varnishes etc.). The incidence of occupational asthma diseases in workers exposed to diisocyanates is high. Typically, a development of the disease begins after a short time exposure. In this thesis, a diagnostic method in suspected occupational allergic disease of the airways is suggested and

  18. Inverse heat transfer problem of thermal contact conductance estimation in periodically contacting surfaces

    NASA Astrophysics Data System (ADS)

    Shojaeefard, M. H.; Goudarzi, K.; Mazidi, M. Sh.

    2009-06-01

    The problems involving periodic contacting surfaces have different practical applications. An inverse heat conduction problem for estimating the periodic Thermal Contact Conductance (TCC) between one-dimensional, constant property contacting solids has been investigated with conjugate gradient method (CGM) of function estimation. This method converges very rapidly and is not so sensitive to the measurement errors. The advantage of the present method is that no a priori information is needed on the variation of the unknown quantities, since the solution automatically determines the functional form over the specified domain. A simple, straight forward technique is utilized to solve the direct, sensitivity and adjoint problems, in order to overcome the difficulties associated with numerical methods. Two general classes of results, the results obtained by applying inexact simulated measured data and the results obtained by using data taken from an actual experiment are presented. In addition, extrapolation method is applied to obtain actual results. Generally, the present method effectively improves the exact TCC when exact and inexact simulated measurements input to the analysis. Furthermore, the results obtained with CGM and the extrapolation results are in agreement and the little deviations can be negligible.

  19. Non-Contact EDDY Current Hole Eccentricity and Diameter Measurement

    NASA Technical Reports Server (NTRS)

    Chern, E. James

    1998-01-01

    Precision holes are among the most critical features of a mechanical component. Deviations from permissible tolerances can impede operation and result in unexpected failure. We have developed an automated non-contact eddy current hole diameter and eccentricity measuring system. The operating principle is based on the eddy current lift-off effect, which is the coil impedance as a function of the distance between the coil and the test object. An absolute eddy current probe rotates in the hole. The impedance of each angular position is acquired and input to the computer for integration and analysis. The eccentricity of the hole is the profile of the impedance as a function of angular position as compared to a straight line, an ideal hole. The diameter of the hole is the sum of the diameter of the probe and twice the distance-calibrated impedance. An eddy current image is generated by integrating angular scans for a plurality of depths between the top and bottom to display the eccentricity profile. This system can also detect and image defects in the hole. The method for non-contact eddy current hole diameter and eccentricity measurement has been granted a patent by the U.S. Patent and Trademark Office.

  20. Teaching Tips on Current Environmental Problems.

    ERIC Educational Resources Information Center

    Busch, Phyllis S.

    This manual, prepared by the Science Project Related to Upgrading Conservation Education (Project S.P.R.U.C.E.), contains suggestions for introducing elementary school students to current environmental problems. Problems treated are population density, social pollution, visual pollution, air pollution, and water pollution. A background discussion…

  1. Inverse source problems for eddy current equations

    NASA Astrophysics Data System (ADS)

    Alonso Rodríguez, Ana; Camaño, Jessika; Valli, Alberto

    2012-01-01

    We study the inverse source problem for the eddy current approximation of Maxwell equations. As for the full system of Maxwell equations, we show that a volume current source cannot be uniquely identified by knowledge of the tangential components of the electromagnetic fields on the boundary, and we characterize the space of non-radiating sources. On the other hand, we prove that the inverse source problem has a unique solution if the source is supported on the boundary of a subdomain or if it is the sum of a finite number of dipoles. We address the applicability of this result for the localization of brain activity from electroencephalography and magnetoencephalography measurements.

  2. Conference on Current Problems in College Administration.

    ERIC Educational Resources Information Center

    Nossell, Jerome, Ed.; Pesci, Frank B., Ed.

    The purpose of the 10-day Conference on Current Problems in College Administration were: (1) to improve the effectiveness and efficiency of the administrative services of Saint Joseph College; (2) to identify the principal areas toward which the College should direct future efforts for improvement; (3) to place the administrative staff in contact…

  3. Comparison between FEBio and Abaqus for biphasic contact problems.

    PubMed

    Meng, Qingen; Jin, Zhongmin; Fisher, John; Wilcox, Ruth

    2013-09-01

    Articular cartilage plays an important role in the function of diarthrodial joints. Computational methods have been used to study the biphasic mechanics of cartilage, and Abaqus has been one of the most widely used commercial software packages for this purpose. A newly developed open-source finite element solver, FEBio, has been developed specifically for biomechanical applications. The aim of this study was to undertake a direct comparison between FEBio and Abaqus for some practical contact problems involving cartilage. Three model types, representing a porous flat-ended indentation test, a spherical-ended indentation test, and a conceptual natural joint contact model, were compared. In addition, a parameter sensitivity study was also performed for the spherical-ended indentation test to investigate the effects of changes in the input material properties on the model outputs, using both FEBio and Abaqus. Excellent agreement was found between FEBio and Abaqus for all of the model types and across the range of material properties that were investigated.

  4. Comparison between FEBio and Abaqus for biphasic contact problems

    PubMed Central

    Jin, Zhongmin; Fisher, John; Wilcox, Ruth

    2013-01-01

    Articular cartilage plays an important role in the function of diarthrodial joints. Computational methods have been used to study the biphasic mechanics of cartilage, and Abaqus has been one of the most widely used commercial software packages for this purpose. A newly developed open-source finite element solver, FEBio, has been developed specifically for biomechanical applications. The aim of this study was to undertake a direct comparison between FEBio and Abaqus for some practical contact problems involving cartilage. Three model types, representing a porous flat-ended indentation test, a spherical-ended indentation test, and a conceptual natural joint contact model, were compared. In addition, a parameter sensitivity study was also performed for the spherical-ended indentation test to investigate the effects of changes in the input material properties on the model outputs, using both FEBio and Abaqus. Excellent agreement was found between FEBio and Abaqus for all of the model types and across the range of material properties that were investigated. PMID:23804955

  5. Electrical impedance tomography problem with inaccurately known boundary and contact impedances.

    PubMed

    Kolehmainen, Ville; Lassas, Matti; Ola, Petri

    2008-10-01

    In electrical impedance tomography (EIT) electric currents are injected into a body with unknown electromagnetic properties through a set of contact electrodes at the boundary of the body. The resulting voltages are measured on the same electrodes and the objective is to reconstruct the unknown conductivity function inside the body based on these data. All the traditional approaches to the reconstruction problem assume that the boundary of the body and the electrode-skin contact impedances are known a priori. However, in clinical experiments one usually lacks the exact knowledge of the boundary and contact impedances, and therefore, approximate model domain and contact impedances have to be used in the image reconstruction. However, it has been noticed that even small errors in the shape of the computation domain or contact impedances can cause large systematic artefacts in the reconstructed images, leading to loss of diagnostically relevant information. In a recent paper (Kolehmainen , 2006), we showed how in the 2-D case the errors induced by the inaccurately known boundary can be eliminated as part of the image reconstruction and introduced a novel method for finding a deformed image of the original isotropic conductivity using the theory of TeichmUller mappings. In this paper, the theory and reconstruction method are extended to include the estimation of unknown contact impedances. The method is implemented numerically and tested with experimental EIT data. The results show that the systematic errors caused by inaccurately known boundary and contact impedances can efficiently be eliminated by the reconstruction method.

  6. Exact Null Controllability of a Nonlinear Thermoelastic Contact Problem

    SciTech Connect

    Sivergina, Irina F. Polis, Michael P.

    2005-01-15

    We study the controllability properties of a nonlinear parabolic system that models the temperature evolution of a one-dimensional thermoelastic rod that may come into contact with a rigid obstacle. Basically the system dynamics is described by a one-dimensional nonlocal heat equation with a nonlinear and nonlocal boundary condition of Newmann type.We focus on the control problem and treat the case when the control is distributed over the whole space domain. In this case the system is proved to be exactly null controllable provided the parameters of the system are smooth.The proof is based on changing the control variable and using Aubin's Compactness Lemma to obtain an invariant set for the linearized controllability map. Then, by proving that the found solution is sufficiently smooth, we get the null controllability for the original system.

  7. Variationally consistent discretization schemes and numerical algorithms for contact problems

    NASA Astrophysics Data System (ADS)

    Wohlmuth, Barbara

    We consider variationally consistent discretization schemes for mechanical contact problems. Most of the results can also be applied to other variational inequalities, such as those for phase transition problems in porous media, for plasticity or for option pricing applications from finance. The starting point is to weakly incorporate the constraint into the setting and to reformulate the inequality in the displacement in terms of a saddle-point problem. Here, the Lagrange multiplier represents the surface forces, and the constraints are restricted to the boundary of the simulation domain. Having a uniform inf-sup bound, one can then establish optimal low-order a priori convergence rates for the discretization error in the primal and dual variables. In addition to the abstract framework of linear saddle-point theory, complementarity terms have to be taken into account. The resulting inequality system is solved by rewriting it equivalently by means of the non-linear complementarity function as a system of equations. Although it is not differentiable in the classical sense, semi-smooth Newton methods, yielding super-linear convergence rates, can be applied and easily implemented in terms of a primal-dual active set strategy. Quite often the solution of contact problems has a low regularity, and the efficiency of the approach can be improved by using adaptive refinement techniques. Different standard types, such as residual- and equilibrated-based a posteriori error estimators, can be designed based on the interpretation of the dual variable as Neumann boundary condition. For the fully dynamic setting it is of interest to apply energy-preserving time-integration schemes. However, the differential algebraic character of the system can result in high oscillations if standard methods are applied. A possible remedy is to modify the fully discretized system by a local redistribution of the mass. Numerical results in two and three dimensions illustrate the wide range of

  8. Straightening of a wavy strip: An elastic-plastic contact problem including snap-through

    NASA Technical Reports Server (NTRS)

    Fischer, D. F.; Rammerstorfer, F. G.

    1980-01-01

    The nonlinear behavior of a wave like deformed metal strip during the levelling process were calculated. Elastic-plastic material behavior as well as nonlinearities due to large deformations were considered. The considered problem lead to a combined stability and contact problem. It is shown that, despite the initially concentrated loading, neglecting the change of loading conditions due to altered contact domains may lead to a significant error in the evaluation of the nonlinear behavior and particularly to an underestimation of the stability limit load. The stability was examined by considering the load deflection path and the behavior of a load-dependent current stiffness parameter in combination with the determinant of the current stiffness matrix.

  9. Interdigitated back contact solar cell with high-current collection

    SciTech Connect

    Garner, C. M.; Nasby, R. D.; Sexton, F. W.; Rodriguez, J. L.; Norwood, D. P.

    1981-01-01

    Internal current-collection efficiencies greater than 90 percent and energy-conversion efficiencies of 18 percent at 30 suns have been measured on a laboratory version of the interdigitated back contact (IBC) solar cell. The quantum efficiency at 600 nm was greater than 90 percent which implies a minority carrier lifetime of greater than 350 ..mu..sec and a front surface recombination velocity of less than 30 cm/sec on the better devices. To achieve these high-current collection efficiencies, a phosphorous gettering diffusion was performed on the front surface and then etched off. Also, thermal oxides were grown on the front and back of the cell to passivate the silicon surfaces. Although the internal collection efficiencies of the cell were high, series resistance caused the fill factor (FF) to decrease at concentrations above 30 suns. Dark current measurements on cells with a new grid spacing indicate that the series resistance is much lower than in the previous cell design. This should result in higher efficiencies at high concentration.

  10. Microscopic Current Flow Patterns in Nanoscale Quantum Point Contacts

    NASA Astrophysics Data System (ADS)

    Sai, Na; Bushong, Neil; Hatcher, Ryan; di Ventra, Massimiliano

    2006-03-01

    Transport in nanoscale conductors has been studied extensively mainly using the stationary scattering approach. However, the dynamical nature of transport, and in particular, the flow patterns of the microscopic current through a nanoscale junction, have remained poorly understood. We apply a novel time-dependent transport approach [1], which combines closed and finite geometries with time-dependent density functional theory,to study current flow patterns in nanoscale quantum point contacts [2]. The results of both atomistic and jellium calculations show that surface charges form dynamically at the junction-electrode interfaces in both abrupt and adiabatic junctions. The curr ent exhibits some characteristics of a classical hydrodynamic liquid but also displays unique patterns arising from the interaction with the surface charges. We also investigate the effect of the flow velocity, charge density, and lattice structures on the electron dynamics. If time permits we also discuss the effects of the viscosity of the electron liquid [3]. Work supported by DOE (DE-FG02-05ER46204). [1] M. Di Ventra and T.N. Todorov, J. Phys. Cond. Matt. 16, 8025 (2004). [2] N. Bushong, N. Sai and, M. Di Ventra, Nano Lett. (in press). [3] N. Sai, M. Zwolak, G. Vignale, and M. Di Ventra, Phys. Rev. Lett. 94, 186810 (2005 ).

  11. AIRBORNE CONTACT DERMATITIS – CURRENT PERSPECTIVES IN ETIOPATHOGENESIS AND MANAGEMENT

    PubMed Central

    Handa, Sanjeev; De, Dipankar; Mahajan, Rahul

    2011-01-01

    The increasing recognition of occupational origin of airborne contact dermatitis has brought the focus on the variety of irritants, which can present with this typical morphological picture. At the same time, airborne allergic contact dermatitis secondary to plant antigens, especially to Compositae family, continues to be rampant in many parts of the world, especially in the Indian subcontinent. The recognition of the contactant may be difficult to ascertain and the treatment may be even more difficult. The present review focuses on the epidemiological, clinical and therapeutic issues in airborne contact dermatitis. PMID:22345774

  12. [Problems with current hypertension definition in children].

    PubMed

    Peco-Antić, Amira

    2008-01-01

    The Task Force data have added immeasurably to our understanding of the normal distribution of blood pressure in children. However, the manner in which arterial hypertension is defined in children is not without problems. The main problem is that the current definition of hypertension in children is not based on the end-organ damage assessment, but on the blood pressure height-related percentile distribution of healthy reference population. This could be overcome by introducing the relationship of blood pressure values with sensitive markers of hypertensive sequelae (such as carotid intimal-medial thickness, left ventricle mass index, retinal arteriolar narrowing and arteriovenous nicking as well as microalbumin urinary excretion) to define better the specific blood pressure values with outcomes. Furthermore, the current definition of hypertension based on the demographic and clinical characteristics of the reference population does not consider the normal evolution of reference population, as well as its ethnic differences. In addition, being based on the single occasion measurement in quite position it does not account for the possibility of transient, stress induced elevations in blood pressure known as white coat hypertension. Therefore, incorporation ambulatory 24 h blood pressure data into the definition of arterial hypertension in children may increase the definition reliability for clinical decision - making, although for such reliability the paediatric normative ambulatory blood pressure data should be improved.

  13. Advances in reduction techniques for tire contact problems

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.

    1995-01-01

    Some recent developments in reduction techniques, as applied to predicting the tire contact response and evaluating the sensitivity coefficients of the different response quantities, are reviewed. The sensitivity coefficients measure the sensitivity of the contact response to variations in the geometric and material parameters of the tire. The tire is modeled using a two-dimensional laminated anisotropic shell theory with the effects of variation in geometric and material parameters, transverse shear deformation, and geometric nonlinearities included. The contact conditions are incorporated into the formulation by using a perturbed Lagrangian approach with the fundamental unknowns consisting of the stress resultants, the generalized displacements, and the Lagrange multipliers associated with the contact conditions. The elemental arrays are obtained by using a modified two-field, mixed variational principle. For the application of reduction techniques, the tire finite element model is partitioned into two regions. The first region consists of the nodes that are likely to come in contact with the pavement, and the second region includes all the remaining nodes. The reduction technique is used to significantly reduce the degrees of freedom in the second region. The effectiveness of the computational procedure is demonstrated by a numerical example of the frictionless contact response of the space shuttle nose-gear tire, inflated and pressed against a rigid flat surface. Also, the research topics which have high potential for enhancing the effectiveness of reduction techniques are outlined.

  14. Current problems in plasma spray processing

    SciTech Connect

    Berndt, C.C.; Brindley, W.; Goland, A.N.; Herman, H.; Houck, D.L.; Jones, K.; Miller, R.A.; Neiser, R.; Riggs, W.; Sampath, S.; Smith, M.; Spanne, P. . Thermal Spray Lab.)

    1991-01-01

    This detailed report summarizes 8 contributions from a thermal spray conference that was held in late 1991 at Brookhaven National Laboratory (Upton, Long Island, NY, USA). The subject of Plasma Spray Processing'' is presented under subject headings of Plasma-particle interactions, Deposit formation dynamics, Thermal properties of thermal barrier coatings, Mechanical properties of coatings, Feed stock materials, Porosity: An integrated approach, Manufacture of intermetallic coatings, and Synchrotron x-ray microtomographic methods for thermal spray materials. Each section is intended to present a concise statement of a specific practical and/or scientific problem, then describe current work that is being performed to investigate this area, and finally to suggest areas of research that may be fertile for future activity.

  15. Current problems in plasma spray processing

    SciTech Connect

    Berndt, C.C.; Brindley, W.; Goland, A.N.; Herman, H.; Houck, D.L.; Jones, K.; Miller, R.A.; Neiser, R.; Riggs, W.; Sampath, S.; Smith, M.; Spanne, P.

    1991-12-31

    This detailed report summarizes 8 contributions from a thermal spray conference that was held in late 1991 at Brookhaven National Laboratory (Upton, Long Island, NY, USA). The subject of ``Plasma Spray Processing`` is presented under subject headings of Plasma-particle interactions, Deposit formation dynamics, Thermal properties of thermal barrier coatings, Mechanical properties of coatings, Feed stock materials, Porosity: An integrated approach, Manufacture of intermetallic coatings, and Synchrotron x-ray microtomographic methods for thermal spray materials. Each section is intended to present a concise statement of a specific practical and/or scientific problem, then describe current work that is being performed to investigate this area, and finally to suggest areas of research that may be fertile for future activity.

  16. A Study of Current Chopping Characteristics in Metal-Carbide Composite Contact Materials

    NASA Astrophysics Data System (ADS)

    Yamamoto, Atsushi; Kusano, Takashi; Okutomi, Tsutomu; Yokokura, Kunio; Homma, Mitsutaka

    To clarify the effect of carbides on current chopping characteristics chopping current was evaluated for various metalcarbide contact materials. As a result, it was found that the chopping current of metal-carbide contacts was related to the vapor pressure of metals and the work function of carbides. It was also found that the chopping current was reduced by the heat treatment when the melting point of contacts is lower than the temperature of heat teatment.

  17. Finite element analysis of 3D elastic-plastic frictional contact problem for Cosserat materials

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Xie, Z. Q.; Chen, B. S.; Zhang, H. W.

    2013-06-01

    The objective of this paper is to develop a finite element model for 3D elastic-plastic frictional contact problem of Cosserat materials. Because 3D elastic-plastic frictional contact problems belong to the unspecified boundary problems with nonlinearities in both material and geometric forms, a large number of calculations are needed to obtain numerical results with high accuracy. Based on the parametric variational principle and the corresponding quadratic programming method for numerical simulation of frictional contact problems, a finite element model is developed for 3D elastic-plastic frictional contact analysis of Cosserat materials. The problems are finally reduced to linear complementarity problems (LCP). Numerical examples show the feasibility and importance of the developed model for analyzing the contact problems of structures with materials which have micro-polar characteristics.

  18. Transient analysis of thermoelastic contact problem of disk brakes

    NASA Astrophysics Data System (ADS)

    Belhocine, Ali; Bouchetara, Mostefa

    2013-06-01

    The main purpose of this study is to analyze the thermomechanical behavior of the dry contact between the brake disk and pads during the braking phase. The simulation strategy is based on computer code ANSYS11. The modeling of transient temperature in the disk is actually used to identify the factor of geometric design of the disk to install the ventilation system in vehicles. The thermal-structural analysis is then used with coupling to determine the deformation established and the Von Mises stresses in the disk, the contact pressure distribution in pads. The results are satisfactory compared to those found in the literature.

  19. A system-approach to the elastohydrodynamic lubrication point-contact problem

    NASA Technical Reports Server (NTRS)

    Lim, Sang Gyu; Brewe, David E.

    1991-01-01

    The classical EHL (elastohydrodynamic lubrication) point contact problem is solved using a new system-approach, similar to that introduced by Houpert and Hamrock for the line-contact problem. Introducing a body-fitted coordinate system, the troublesome free-boundary is transformed to a fixed domain. The Newton-Raphson method can then be used to determine the pressure distribution and the cavitation boundary subject to the Reynolds boundary condition. This method provides an efficient and rigorous way of solving the EHL point contact problem with the aid of a supercomputer and a promising method to deal with the transient EHL point contact problem. A typical pressure distribution and film thickness profile are presented and the minimum film thicknesses are compared with the solution of Hamrock and Dowson. The details of the cavitation boundaries for various operating parameters are discussed.

  20. Service Provision: Recent Gains, Current Problems.

    ERIC Educational Resources Information Center

    BCEL Newsletter for the Business Community, 1988

    1988-01-01

    Organizations and groups responsible for the bulk of the nation's adult basic skills provision are currently reaching an estimated 9-10 percent of the needy population. This represents an increase from the 7-8 percent reached in 1984. Adult Basic Education (ABE), the largest single program in the nation, has shown an overall growth in enrollment…

  1. Current structural vibration problems associated with noise

    NASA Technical Reports Server (NTRS)

    Mixson, J. S.

    1974-01-01

    As the performance of aerospace vehicles has increased, the noise generated by the propulsion system and by the passage of the vehicle through the air has also increased. Further increases in performance are now underway for space vehicles such as the space shuttle vehicle and for short distance takeoff and landing (STOL) aircraft, and are being planned for supersonic aircraft. The flight profiles and design features of these high-performance vehicles are reviewed and an estimate made of selected noise-induced structural vibration problems. Considerations for the prevention of acoustic fatigue, noise transmission, and electronic instrument malfunction are discussed.

  2. Plane transient contact problem for rough sliding bodies with wear and heat generation

    NASA Astrophysics Data System (ADS)

    Yevtushenko, A. A.; Pauk, V. Jo.

    1994-04-01

    Experimental investigation corroborates the interdependence of processes and phenomena taking place in the contact of solids. Previous publications are concerned with simultaneous calculation of the microgeometry of surfaces of bodies, their wear and the heat due to friction in the contact zone in steady contact problems. In the present paper an analogous contact problem has been considered. The model employs the Archard law of wear, in which the rate of material removal is proportional to pressure and speed of sliding. Contact pressure and temperatures at the interface are found from the solution of two governing integral equations. Green's functions are used to investigate the stresses and temperatures inside the two elastic bodies for a variety of material combinations and operating conditions.

  3. THE CURRENT PROBLEMS OF NONSPECIFIC BACK PAIN.

    PubMed

    Seleznova, S; Zabara, A; Mamuladze, D

    2016-01-01

    The article deals with various aspects of pain in degenerative diseases of the spine and with the actual problems of non-specific back pain. The data on the mechanisms of pain and analgesic treatment algorithms of the patients with radicular syndrome, and pharmacological and non-pharmacological therapies is provided. The effect of structural-modifying drugs in relief of nonspecific back pain was investigated and compared with a traditional nonsteroidal anti-inflammatory drug (NSAID) therapy in combination with B vitamins, without chondroprotectors. The study population was composed of 85 patients (42 men and 43 women) aged 38 to 68 years (mean age - (46,3±2,6) years) with chronic vertebral pain syndromes (VPS). For objectification assessment of pain, severity of pain, and evaluate the effectiveness of therapy we used the visual analog scale (VAS).The majority (88%) of the patients included in the study, complained of a moderately severe pain (from 40 to 70 mm on the VAS). Patients were divided into two groups. The first (primary) group consisted of 55 patients (30 men and 25 women). The following treatment was applied: all patients of the first group, in addition to the NSAID administered with hondroprotektror arbitrarily - Struktum 1000 mg twice a day or 300 mg Piaskledin once a day for 40-60 days.The second (control) group consisted of 30 patients (14 men, 16 women). Patients in the control group administered with a traditional NSAID therapy in combination with B vitamins, without chondroprotectors. The results of the study on the influence of drugs Piaskledin 300, Struktum for the relief of nonspecific back pain revealed that in the treatment of vertebral pain, a combination of non-steroidal anti-inflammatory drugs with structure-modifying agents could achieve rapid rehabilitation of patients with locomotor activity and improve quality of life in general. PMID:26870977

  4. [Current progress and problems in oncourology].

    PubMed

    Chakŭrov, S

    2007-01-01

    One of the most serious problems of urology as specialized surgery is the oncological diseases. A large part of the scientific research is dedicated to their basic research, diagnostics and treatment as the results are then presented at the big international forums each year. The new achievements in the investigations of urological diseases excite special interest and mark the stages of the actual progress of the respective science. The overview is a panorama of the newest and at the same time most significant achievements of the science of urology in this field in 2006 presented at the biggest international congresses - the Congress of the European Association of Urology, the Annual Meeting of the American urologists and the Congress of the American Society of Clinical Oncology - ASCO. What is typical is the existence of the large number of researches of the carcinoma of the prostate - an issue on which the urological society focuses its attention quite often. Without any revolutionary breakthroughs being made new scientific proof has been added which considerably enriches our knowledge about this disease and places special focus on the real value and interpretation of the levels of the Prostate Specific Antigen (PSA). What is especially impressive in bladder cancer research is the discovery of a protein element called "survivin", which is of the family of the inhibitors of apoptosis and its level is connected with qualities of the tumors like aggressiveness, recurrence and progression of the disease and mortality rate. The weight of the scientific research in the field of kidney tumors is placed on the basic research of their oncogenesis. After quite a few years of standstill in the area of chemotherapy new drugs like Sunitinib, Sorafenib and Temserolimus are being introduced, some of which even have independent antitumor effect. As far as the testicle tumors are concerned, the necessity of an extensive lymphadenectomy is confirmed. The increased possibilities of

  5. Effect of photovoltage on current flow in metal-semiconductor schottky-barrier contacts

    SciTech Connect

    Torkhov, N. A.

    2011-07-15

    It is shown that changes in device characteristics and an increase in the light-to-electrical energy conversion efficiency in metal-semiconductor Schottky barrier contacts are associated with a peripheral electric field built into the contact. For contacts with longer perimeters, variations in device characteristics and the light-to-electrical energy conversion efficiency are significantly larger. Since the photovoltage and peripheral electric fields in the contact region are codirected with the intrinsic electric field of the space-charge region, contact illumination results in a larger increase in the 'dead' zone in forward portions of current-voltage characteristics, a larger decrease in the effective Schottky barrier height, and an increase in the field electron emission. An increase in the reverse field emission under photovoltage leads to an increase in the recombination current in the space-charge region, which provides dc photocurrent flow in the circuit.

  6. Switch contact device for interrupting high current, high voltage, AC and DC circuits

    DOEpatents

    Via, Lester C.; Witherspoon, F. Douglas; Ryan, John M.

    2005-01-04

    A high voltage switch contact structure capable of interrupting high voltage, high current AC and DC circuits. The contact structure confines the arc created when contacts open to the thin area between two insulating surfaces in intimate contact. This forces the arc into the shape of a thin sheet which loses heat energy far more rapidly than an arc column having a circular cross-section. These high heat losses require a dramatic increase in the voltage required to maintain the arc, thus extinguishing it when the required voltage exceeds the available voltage. The arc extinguishing process with this invention is not dependent on the occurrence of a current zero crossing and, consequently, is capable of rapidly interrupting both AC and DC circuits. The contact structure achieves its high performance without the use of sulfur hexafluoride.

  7. Exposure to electrical contact currents and the risk of childhood leukemia.

    PubMed

    Does, Monique; Scélo, Ghislaine; Metayer, Catherine; Selvin, Steve; Kavet, Robert; Buffler, Patricia

    2011-03-01

    The objectives of this study were to examine the association between contact current exposure and the risk of childhood leukemia and to investigate the relationship between residential contact currents and magnetic fields. Indoor and outdoor contact voltage and magnetic-field measurements were collected for the diagnosis residence of 245 cases and 269 controls recruited in the Northern California Childhood Leukemia Study (2000-2007). Logistic regression techniques produced odds ratios (OR) adjusted for age, sex, Hispanic ethnicity, mother's race and household income. No statistically significant associations were seen between childhood leukemia and indoor contact voltage level [exposure ≥90th percentile (10.5 mV): OR  =  0.83, 95% confidence interval (CI): 0.45, 1.54], outdoor contact voltage level [exposure ≥90th percentile (291.2 mV): OR  =  0.89, 95% CI: 0.48, 1.63], or indoor magnetic-field levels (>0.20 µT: OR  =  0.76, 95% CI: 0.30, 1.93). Contact voltage was weakly correlated with magnetic field; correlation coefficients were r  =  0.10 (P  =  0.02) for indoor contact voltage and r  =  0.15 (P  =  0.001) for outdoor contact voltage. In conclusion, in this California population, there was no evidence of an association between childhood leukemia and exposure to contact currents or magnetic fields and a weak correlation between measures of contact current and magnetic fields.

  8. Contact problem for an elastic reinforcement bonded to an elastic plate

    NASA Technical Reports Server (NTRS)

    Erdogan, F.; Civelek, M. B.

    1974-01-01

    The contact problem for a thin elastic reinforcement bonded to an elastic plate is considered. The stiffening layer is treated as an elastic membrane and the base plate is assumed to be an elastic continuum. The bonding between the two materials is assumed to be either one of direct adhesion or through a thin adhesive layer which is treated as a shear spring. The solution for the simple case in which both the stiffener and the base plate are treated as membranes is also given. The contact stress is obtained for a series of numerical examples. In the direct adhesion case the contact stress becomes infinite at the stiffener ends with a typical square root singularity for the continuum model and behaving as a delta function for the membrane model. In the case of bonding through an adhesive layer the contact stress becomes finite and continuous along the entire contact area.

  9. A Jacobian-free Newton Krylov method for mortar-discretized thermomechanical contact problems

    NASA Astrophysics Data System (ADS)

    Hansen, Glen

    2011-07-01

    Multibody contact problems are common within the field of multiphysics simulation. Applications involving thermomechanical contact scenarios are also quite prevalent. Such problems can be challenging to solve due to the likelihood of thermal expansion affecting contact geometry which, in turn, can change the thermal behavior of the components being analyzed. This paper explores a simple model of a light water reactor nuclear fuel rod, which consists of cylindrical pellets of uranium dioxide (UO 2) fuel sealed within a Zircalloy cladding tube. The tube is initially filled with helium gas, which fills the gap between the pellets and cladding tube. The accurate modeling of heat transfer across the gap between fuel pellets and the protective cladding is essential to understanding fuel performance, including cladding stress and behavior under irradiated conditions, which are factors that affect the lifetime of the fuel. The thermomechanical contact approach developed here is based on the mortar finite element method, where Lagrange multipliers are used to enforce weak continuity constraints at participating interfaces. In this formulation, the heat equation couples to linear mechanics through a thermal expansion term. Lagrange multipliers are used to formulate the continuity constraints for both heat flux and interface traction at contact interfaces. The resulting system of nonlinear algebraic equations are cast in residual form for solution of the transient problem. A Jacobian-free Newton Krylov method is used to provide for fully-coupled solution of the coupled thermal contact and heat equations.

  10. Spin current source based on a quantum point contact with local spin-orbit interaction

    SciTech Connect

    Nowak, M. P.; Szafran, B.

    2013-11-11

    Proposal for construction of a source of spin-polarized current based on quantum point contact (QPC) with local spin-orbit interaction is presented. We show that spin-orbit interaction present within the narrowing acts like a spin filter. The spin polarization of the current is discussed as a function of the Fermi energy and the width of the QPC.

  11. Contact Effects in thin 3D-Topological Insulators: How does the current flow?

    PubMed Central

    Gupta, Gaurav; Jalil, Mansoor Bin Abdul; Liang, Gengchiau

    2015-01-01

    The effect of different contact configurations (semi-infinite extended-channel, normal metal and ferromagnetic metal) on quantum transport through thin Bi2Se3 three-dimensional (3D) topological insulator (TI) slab (channel) has been investigated through Non-Equilibrium Green Function. The issue of contact dependent current flow and distribution across quintuple layers of 3D-TI has been addressed in this work and applied to expound the explanation for recent experimental work on electrical detection of spin-momentum locking on topological surface for long channel device. A theoretical model is propounded to develop a microscopic understanding of transport in 3D-TI in which contact type and magnetization concur with helical surface states of the TI channel to manifest seemingly counter-intuitive current distribution across layers. The quantum transport calculations for short channel devices with magnetic source and drain contacts postulate negative surface current for anti-phase magnetization whose axis is transverse to both current and quintuple layers. For in-phase magnetization at the two terminals, it is shown that observations can change fundamentally to result in anomalous current distribution. Such results are explained to stem from the confinement of 3D-TI between ferromagnetic contacts along the transport direction. A simple mechanism to validate topological insulators via quantum transport experiments has also been suggested. PMID:25820460

  12. Assessment of exposure to intermediate frequency electric fields and contact currents from a plasma ball.

    PubMed

    Alanko, Tommi; Puranen, Lauri; Hietanen, Maila

    2011-12-01

    While electric fields at intermediate frequencies are not widely utilized for industrial technologies, surprisingly, certain toys emit the highest electric fields found in our living environment. These toys, plasma balls, are devices that use high voltage to create ionized light discharges. In this study, we assessed exposure to electric fields and contact/induced current from a recreational plasma ball device. The electric field strength was measured as a function of distance from the device, and the contact/induced current was measured with a current clamp in different exposure situations with point or grasping contact. The characteristic spectra of the electric field and contact current were measured, and both the multiple frequency rule and weighting of the spectra were applied according to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) 1998 and 2010 guidelines. The results indicate that the recommended reference levels for the general public are exceeded at distances <1.2 m, and that the contact currents in the hand may be twice higher than recommended by the general public guidelines.

  13. Formulation of Contact Problems in Sheet Metal Forming Simulation Using Local Interpolation for Tool Surfaces

    NASA Astrophysics Data System (ADS)

    Hama, Takayuki; Takamura, Masato; Makinouchi, Akitake; Teodosiu, Cristian; Takuda, Hirohiko

    The treatment of contact between a sheet and tools is one of the most difficult problems to deal with in finite-element simulations of the sheet metal forming processes. In order to obtain more accurate tool models without increasing the number of elements, this paper describes new techniques for the contact problem using a local interpolation for tool surfaces proposed by Nagata. The Nagata patch enables the creation of tool models that are much more accurate in shape than those of the conventional polyhedral representations. Contact search algorithms between the sheet nodes and the interpolated tool surfaces and a consistent contact tangent stiffness matrix for the sliding sheet nodes were formulated. The proposed contact search algorithms allow robust and accurate contact analyses. The developed algorithms were introduced into the static-explicit elastoplastic finite-element method code STAMP3D. Simulations of a square-cup deep-drawing process with a very coarsely discretized punch model were carried out. The simulated results showed that the proposed algorithms yield the proper deformation process, thus demonstrating the validity of the proposed techniques.

  14. A constitutive law for finite element contact problems with unclassical friction

    NASA Technical Reports Server (NTRS)

    Plesha, M. E.; Steinetz, B. M.

    1986-01-01

    Techniques for modeling complex, unclassical contact-friction problems arising in solid and structural mechanics are discussed. A constitutive modeling concept is employed whereby analytic relations between increments of contact surface stress (i.e., traction) and contact surface deformation (i.e., relative displacement) are developed. Because of the incremental form of these relations, they are valid for arbitrary load-deformation histories. The motivation for the development of such a constitutive law is that more realistic friction idealizations can be implemented in finite element analysis software in a consistent, straightforward manner. Of particular interest is modeling of two-body (i.e., unlubricated) metal-metal, ceramic-ceramic, and metal-ceramic contact. Interfaces involving ceramics are of engineering importance and are being considered for advanced turbine engines in which higher temperature materials offer potential for higher engine fuel efficiency.

  15. Methodological aspects of the problem of the intermediary language for the contact of intelligent systems

    NASA Astrophysics Data System (ADS)

    Zaretskaia-Chukreeva, O. A.

    1990-10-01

    Methodological aspects of the problem of the intermediary languages (ILs) for contact with hypothetical extraterrestrial civilizations is addressed. The concepts of super-system, demand, and determinants developed by Mel'nikov (1978). A typology of intelligent systems is outlined with indications of appropriate ILs for the various types.

  16. Survey of current component reliability problems and methods for prevention.

    NASA Technical Reports Server (NTRS)

    Hamiter, L.; Villella, F.

    1972-01-01

    The current reliability problems related to electronic components and microcircuits are presented in this paper. Specific process controls, design, materials, application constraints, destructive testing, electrical tests, and procedures for implementation are recommended to improve the reliability of selected electronic components.

  17. Excess currents larger than the point contact limit in normal-metal/superconducting junctions

    NASA Astrophysics Data System (ADS)

    Riedel, Richard; Bagwell, Philip F.

    1999-05-01

    In a point contact NS junction, perfect Andreev reflection occurs over a range of voltages equal to the superconducting energy gap, producing an excess current of Iexc = (4 / 3)(2 eΔ / h). If the superconductor has a finite width, rather than the infinite width of the point contact, one cannot neglect superfluid flow inside the superconducting contact. The energy range available for perfect Andreev reflections then becomes larger than the superconducting gap, since superfluid flow alters the dispersion relation inside the finite width superconductor. We find a maximum excess current of approximately (7 / 3)(2 eΔ / h) when the width of the superconductor is approximately 7 / 3 times the width of the normal metal.

  18. Three-dimensional crack and contact problems with a general geometric configuration

    NASA Astrophysics Data System (ADS)

    Yong, Z.; Hanson, M. T.

    1994-02-01

    A NEW METHOD, based on point set theory and properties of orthogonal functions, is developed for determining exact solutions to three-dimensional crack and contact problems with complicated geometric configurations (e.g. a star-convex domain) in an infinite linear elastic medium. The governing equation is a two-dimensional Fredholm integral equation of the first kind. The central idea of this method is the chain extension of an exact solution from a regular subdomain to an irregular entire domain. Examples are given illustrating how this solution procedure can be used to obtain exact closed form solutions for a general Hertz contact problem and various crack problems in an inhomogeneous isotropic medium with an elastic modulus which is a power function of depth.

  19. On the the Contact Lens Problem: Modeling Rigid and Elastic Beams on Thin Films

    NASA Astrophysics Data System (ADS)

    Trinh, Philippe; Wilson, Stephen; Stone, Howard

    2011-11-01

    Generally, contact lenses are prescribed by the practitioner to fit each individual patient's eye, but these fitting-philosophies are based on empirical studies and a certain degree of trial-and-error. A badly fitted lens can cause a range of afflictions, which varies from mild dry-eye-discomfort, to more serious corneal diseases. Thus, at this heart of this problem, is the question of how a rigid or elastic plate interacts with the free-surface of a thin viscous film. In this talk, we present several mathematical models for the study of these plate-and-fluid problems. Asymptotic and numerical results are described, and we explain the role of elasticity, surface tension, viscosity, and pressure in determining the equilibrium solutions. Finally, we discuss the implications of our work on the contact lens problem, as well as on other coating processes which involve elastic substrates.

  20. Modeling and analysis of a contact problem for a viscoelastic rod

    NASA Astrophysics Data System (ADS)

    Bartosz, Krzysztof; Sofonea, Mircea

    2016-10-01

    We consider a nonlinear viscoelastic rod which is in contact with a foundation along its length and is in contact with an obstacle at its end. The rod is acted up by body forces and, as a result, its mechanical state evolves. Our aim in this paper is twofold. The first one is to construct an appropriate mathematical model which describes the evolution of the rod. The second one is to prove the weak solvability of the problem. To this end, we use arguments on second-order inclusions with multivalued pseudomonotone operators.

  1. Hole current impedance and electron current enhancement by back-contact barriers in CdTe thin film solar cells

    NASA Astrophysics Data System (ADS)

    Pan, Jun; Gloeckler, Markus; Sites, James R.

    2006-12-01

    The combined effects of a significant back-contact barrier and a low absorber carrier density frequently alter the current-voltage (J-V) characteristics of CdTe solar cells. This combination leads to two competing mechanisms that can alter the J-V characteristics in two different ways. One is a majority-carrier (hole) limitation on current in forward bias that reduces the fill factor and efficiency of the solar cell. The second is a high minority-carrier (electron) contribution to the forward diode current that results in a reduced open-circuit voltage. CdTe solar cells are particularly prone to the latter, since the combination of a wide depletion region and impedance of light-generated holes at the back contact increases the electron injection at the front diode. The overlap of front and back space-charge regions will generally enhance the electron current, but is not a requirement for substantially increased forward current. The simulated J-V curves, illustrating the two major effects, are in good agreement with the experimental curves that have been observed in recent years.

  2. Current densities and total contact currents for 110 and 220 kV power line tasks.

    PubMed

    Korpinen, Leena; Kuisti, Harri; Elovaara, Jarmo

    2014-10-01

    The aim of this study was to analyze all values of electric current from measured periods while performing tasks on 110 and 220 kV power lines. Additionally, the objective was to study the average current densities and average total contact currents caused by electric fields in 110 and 220 kV power line tasks. One worker simulated the following tasks: (A) tested insulation voltage at a 110 kV portal tower, (B) checked the wooden towers for rot at a 110 kV portal tower, (C) tested insulation voltage at a 220 kV portal tower, and (D) checked the wooden towers for rot at a 220 kV portal tower. The highest average current density in the neck was 2.0 mA/m(2) (calculated internal electric field was 19.0-38.0 mV/m), and the highest average contact current was 234 µA. All measured values at 110 and 220 kV towers were lower than the basic restrictions (0.1 and 0.8 V/m) of the International Commission on Non-ionizing Radiation Protection.

  3. Kalker's algorithm Fastsim solves tangential contact problems with slip-dependent friction and friction anisotropy

    NASA Astrophysics Data System (ADS)

    Piotrowski, J.

    2010-07-01

    This paper presents two extensions of Kalker's algorithm Fastsim of the simplified theory of rolling contact. The first extension is for solving tangential contact problems with the coefficient of friction depending on slip velocity. Two friction laws have been considered: with and without recuperation of the static friction. According to the tribological hypothesis for metallic bodies shear failure, the friction law without recuperation of static friction is more suitable for wheel and rail than the other one. Sample results present local quantities inside the contact area (division to slip and adhesion, traction) as well as global ones (creep forces as functions of creepages and rolling velocity). For the coefficient of friction diminishing with slip, the creep forces decay after reaching the maximum and they depend on the rolling velocity. The second extension is for solving tangential contact problems with friction anisotropy characterised by a convex set of the permissible tangential tractions. The effect of the anisotropy has been shown on examples of rolling without spin and in the presence of pure spin for the elliptical set. The friction anisotropy influences tangential tractions and creep forces. Sample results present local and global quantities. Both extensions have been described with the same language of formulation and they may be merged into one, joint algorithm.

  4. Current driven tri-stable resistance states in magnetic point contacts.

    PubMed

    Yanson, I K; Fisun, V V; Naidyuk, Yu G; Balkashin, O P; Triputen, L Yu; Konovalenko, A; Korenivski, V

    2009-09-01

    Point contacts between normal and ferromagnetic metals are investigated using magnetoresistance and transport spectroscopy measurements combined with micromagnetic simulations. Pronounced hysteresis in the point contact resistance versus both bias current and external magnetic field are observed. It is found that such hysteretic resistance can exhibit, in addition to bi-stable resistance states found in ordinary spin valves, tri-stable resistance states with a middle resistance level. We interpret these observations in terms of surface spin valve and spin vortex states, originating from a substantially modified spin structure at the ferromagnetic interface in the contact core. We argue that these surface spin states, subject to a weakened exchange interaction, dominate the effects of spin transfer torques on the nanometer scale. PMID:21828625

  5. Optimization of the heating surface shape in the contact melting problem

    NASA Technical Reports Server (NTRS)

    Fomin, Sergei A.; Cheng, Shangmo

    1991-01-01

    The theoretical analysis of contact melting by the migrating heat source with an arbitrary shaped isothermal heating surface is presented. After the substantiated simplification, the governing equations are transformed to the convenient equations for engineering calculations relationships. Analytical solutions are used for numerical prediction of optimal shape of the heating surface. The problem is investigated for the constant and for temperature dependent physical properties of the melt.

  6. Current Quality-of-Life Tools Available for Use in Contact Dermatitis.

    PubMed

    Swietlik, Jacquelyn; Reeder, Margo

    2016-01-01

    Contact dermatitis is a common dermatologic condition that can cause significant impairment in patients' overall quality of life (QoL). This impact is separate and potentially more clinically relevant than one's disease "severity" in contact dermatitis and should be consistently addressed by dermatologists. Despite this, QoL tools specific to contact dermatitis are lacking, and there is little consistency in the literature regarding the tool used to evaluate clinical response to therapies. Measurements currently available to evaluate disease-related QoL in contact dermatitis fit into 1 of the following 3 general types: generic health-related QoL measures, dermatology-related QoL measures, or specific dermatologic disease-related QoL measures. This article reviews the strengths and weaknesses of existing QoL tools used in contact dermatitis including: Short Form Survey 36, Dermatology Life Quality Index, Skindex-29, Skindex-16, Dermatology-Specific Quality of Life, and Fragrance Quality of Life Index.

  7. Workshops and problems for benchmarking eddy current codes

    SciTech Connect

    Turner, L.R.; Davey, K.; Ida, N.; Rodger, D.; Kameari, A.; Bossavit, A.; Emson, C.R.I.

    1988-08-01

    A series of six workshops was held in 1986 and 1987 to compare eddy current codes, using six benchmark problems. The problems included transient and steady-state ac magnetic fields, close and far boundary conditions, magnetic and non-magnetic materials. All the problems were based either on experiments or on geometries that can be solved analytically. The workshops and solutions to the problems are described. Results show that many different methods and formulations give satisfactory solutions, and that in many cases reduced dimensionality or coarse discretization can give acceptable results while reducing the computer time required. A second two-year series of TEAM (Testing Electromagnetic Analysis Methods) workshops, using six more problems, is underway. 12 refs., 15 figs., 4 tabs.

  8. Adaptive meshing technique applied to an orthopaedic finite element contact problem.

    PubMed

    Roarty, Colleen M; Grosland, Nicole M

    2004-01-01

    Finite element methods have been applied extensively and with much success in the analysis of orthopaedic implants. Recently a growing interest has developed, in the orthopaedic biomechanics community, in how numerical models can be constructed for the optimal solution of problems in contact mechanics. New developments in this area are of paramount importance in the design of improved implants for orthopaedic surgery. Finite element and other computational techniques are widely applied in the analysis and design of hip and knee implants, with additional joints (ankle, shoulder, wrist) attracting increased attention. The objective of this investigation was to develop a simplified adaptive meshing scheme to facilitate the finite element analysis of a dual-curvature total wrist implant. Using currently available software, the analyst has great flexibility in mesh generation, but must prescribe element sizes and refinement schemes throughout the domain of interest. Unfortunately, it is often difficult to predict in advance a mesh spacing that will give acceptable results. Adaptive finite-element mesh capabilities operate to continuously refine the mesh to improve accuracy where it is required, with minimal intervention by the analyst. Such mesh adaptation generally means that in certain areas of the analysis domain, the size of the elements is decreased (or increased) and/or the order of the elements may be increased (or decreased). In concept, mesh adaptation is very appealing. Although there have been several previous applications of adaptive meshing for in-house FE codes, we have coupled an adaptive mesh formulation with the pre-existing commercial programs PATRAN (MacNeal-Schwendler Corp., USA) and ABAQUS (Hibbit Karlson and Sorensen, Pawtucket, RI). In doing so, we have retained several attributes of the commercial software, which are very attractive for orthopaedic implant applications.

  9. Non-uniform space charge limited current injection into a nano contact solid

    PubMed Central

    Zhu, Y. B.; Ang, L. K.

    2015-01-01

    We have developed a two-dimensional (2D) non-uniform model to study the space charge limited (SCL) current injection into a trap-filled solid of nano-contact, such as organic materials and dielectrics. Assuming a solid of length D with a contact of width W, the enhancement over the well-known 1D uniform model is calculated as a function of W/D for different material properties, such as the dielectric constant (ε) and the trap distribution. The non-uniform current density profile due to edge effect is predicted. The findings reported here are different from the prior uniform 2D models, which are significant for small W/D when the size of the contact reaching nanometer scale, i.e. W = 50 nm for D = 1 μm. This model will be useful for the characterization of carrier mobility and properties of traps, which are critical to many novel devices (with small nano-contact) operating in the space charge limited condition reporting in novel device and its applications. Empirical formulas are given for future comparison with experimental results. PMID:25779769

  10. Non-uniform space charge limited current injection into a nano contact solid.

    PubMed

    Zhu, Y B; Ang, L K

    2015-01-01

    We have developed a two-dimensional (2D) non-uniform model to study the space charge limited (SCL) current injection into a trap-filled solid of nano-contact, such as organic materials and dielectrics. Assuming a solid of length D with a contact of width W, the enhancement over the well-known 1D uniform model is calculated as a function of W/D for different material properties, such as the dielectric constant (ε) and the trap distribution. The non-uniform current density profile due to edge effect is predicted. The findings reported here are different from the prior uniform 2D models, which are significant for small W/D when the size of the contact reaching nanometer scale, i.e. W = 50 nm for D = 1 μm. This model will be useful for the characterization of carrier mobility and properties of traps, which are critical to many novel devices (with small nano-contact) operating in the space charge limited condition reporting in novel device and its applications. Empirical formulas are given for future comparison with experimental results. PMID:25779769

  11. Computational dosimetry for grounded and ungrounded human models due to contact current

    NASA Astrophysics Data System (ADS)

    Chan, Kwok Hung; Hattori, Junya; Laakso, Ilkka; Hirata, Akimasa; Taki, Masao

    2013-08-01

    This study presents the computational dosimetry of contact currents for grounded and ungrounded human models. The uncertainty of the quasi-static (QS) approximation of the in situ electric field induced in a grounded/ungrounded human body due to the contact current is first estimated. Different scenarios of cylindrical and anatomical human body models are considered, and the results are compared with the full-wave analysis. In the QS analysis, the induced field in the grounded cylindrical model is calculated by the QS finite-difference time-domain (QS-FDTD) method, and compared with the analytical solution. Because no analytical solution is available for the grounded/ungrounded anatomical human body model, the results of the QS-FDTD method are then compared with those of the conventional FDTD method. The upper frequency limit for the QS approximation in the contact current dosimetry is found to be 3 MHz, with a relative local error of less than 10%. The error increases above this frequency, which can be attributed to the neglect of the displacement current. The QS or conventional FDTD method is used for the dosimetry of induced electric field and/or specific absorption rate (SAR) for a contact current injected into the index finger of a human body model in the frequency range from 10 Hz to 100 MHz. The in situ electric fields or SAR are compared with the basic restrictions in the international guidelines/standards. The maximum electric field or the 99th percentile value of the electric fields appear not only in the fat and muscle tissues of the finger, but also around the wrist, forearm, and the upper arm. Some discrepancies are observed between the basic restrictions for the electric field and SAR and the reference levels for the contact current, especially in the extremities. These discrepancies are shown by an equation that relates the current density, tissue conductivity, and induced electric field in the finger with a cross-sectional area of 1 cm2.

  12. Soldered Contact and Current Risetime Effects on Negative Polarity Wire Array Z-pinches

    SciTech Connect

    Chalenski, D. A.; Kusse, B. R.; Greenly, J. B.; Blesener, I. C.; McBride, R. D.; Hammer, D. A.; Knapp, P. F.

    2009-01-21

    The Cornell University COBRA pulser is a nominal 1 MA machine, capable of driving up to 32 wire cylindrical Z-pinch arrays. COBRA can operate with variable current risetimes ranging from 100 ns to 200 ns (short and long pulse, respectively). Wires are typically strung with a 'press' contact to the electrode hardware, where the wire is loosely pulled against the hardware and held there to establish electrical contact. The machine is normally negative, but a bolt-on convolute can be used to modify the current path and effectively produce positive polarity operation at the load.Previous research with single wires on a 1-5 kA pulser has shown that soldering the wire, thereby improving the wire/electrode contact, and operating in positive polarity can improve the energy deposition into the wire and enhance wire core expansion. Negative polarity showed no difference. Previous experiments on the negative polarity, 20 MA, 100 ns Z accelerator have shown that improving the contact improved the x-ray yield.Cornell data were collected on 16-wire Aluminum Z-pinch arrays in negative polarity. Experiments were conducted with both short and long current pulses with soldered and no-soldered wire/electrode contacts. The initiation, ablation, implosion and stagnation phases were compared for these four conditions. Time dependent x-ray signals were measured using diodes and diamond detectors. An inductive voltage monitor was used to infer minimum current radius achieved, as defined by a uniform shell of current moving radially inward, producing a time dependent inductance. Total energy data were collected with a metal-strip bolometer. Self-emission data were collected by an XUV 4-frame camera and an optical streak camera.In negative polarity and with short pulses, soldering appeared to produce a smaller radius pinch and decrease variations in the x-ray pulse shape. The bolometer, laser backlighter, 4-frame and streak cameras showed negligible differences in the initiation ablation

  13. Higher Education in the Philippines: An Overview and Current Problems

    ERIC Educational Resources Information Center

    Perlman, Daniel H.

    1978-01-01

    Among current problems facing higher education in the Philippines are (1) bilingualism (English and Filipino), (2) accreditation, (3) government regulations, (4) overproduction of graduates, (5) mismatch between graduates and needed skills, (6) imbalance between public and private schools, (7) overconcentration of students in Manila, and (8)…

  14. Current Domestic Problems, Social Studies: 6416.18.

    ERIC Educational Resources Information Center

    Moore, John A.

    Secondary students learn to deal objectively with domestic issues and problems in this quinmester elective course. Emphasis is upon providing students with an opportunity for indepth study in critical thinking on current controversial issues, using activity units as a principal teaching technique. The objectives are for students to identify and…

  15. [Patient safety, – a current and ongoing problem].

    PubMed

    Díaz, Carlos Alberto; Braem, Virginia; Giuliani, Amalia; Restelli, Emilio

    2014-04-22

    Patient safety is a current and ongoing problem of increasing importance in healthcare. The implementation of a safety culture leads to behavioral change in all processes and responsibility centers. It means a long, slow, arduous path and requires effort, persistence and commitment, but it is increasingly necessary and indispensable in hospital management.

  16. AACSB Accreditation in China--Current Situation, Problems, and Solutions

    ERIC Educational Resources Information Center

    Zhang, Xinrui; Gao, Yan

    2012-01-01

    This paper first introduces the background of the AACSB (Association to Advance Collegiate Schools of Business) accreditation, and then analyzes the current status of the participation of Chinese business schools in AACSB accreditation. Based on the data analysis, the paper points out that there are two main problems in the Chinese business…

  17. Publication analysis of the contact lens field: What are the current topics of interest?

    PubMed Central

    Cardona, Genís; Sanz, Joan P.

    2014-01-01

    Purpose To determine the main current research interests of scientists working in the contact lens field. Methods All articles published in the 2011 issues of all journals included in the Journal Citation Reports subject category Ophthalmology were inspected to expose those papers related to the contact lens field. Information regarding source journal was obtained and authorship details were recorded to determine the top most prolific authors, institutions and countries. A comprehensive list of key words was compiled to generate a two-dimensional term map in which the frequency of occurrence of a particular term is defined by label size and the distance between two terms is an indication of the relatedness of these terms, based on their co-occurrences within groups of key words. Clusters of related terms were also identified. Results Visual examination of all articles uncovered a total of 156 papers, published in 28 different journals. Contact Lens & Anterior Eye, Eye & Contact Lens and Optometry and Vision Science had 27 articles each. The most prolific authors and institutions revealed the predominance of countries with long research tradition in the contact lens field. Ten different word clusters or areas of interest were identified, including both traditional, yet unresolved issues (e.g., comfort or dry eye), and the latest research efforts (e.g., myopia control). Conclusions These findings, which revealed contact lenses to be a fertile area of research, may be of relevance to new researchers as well as to those interested in exploring the latest research trends in this scientific discipline. PMID:25649639

  18. Driving forces in moving-contact problems of dynamic elasticity: Indentation, wedging and free sliding

    NASA Astrophysics Data System (ADS)

    Slepyan, Leonid I.; Brun, Michele

    2012-11-01

    The steady-state solution for an elastic half-plane under a moving frictionless smooth indenter of arbitrary shape is derived based on the corresponding transient problem and on a condition concerning energy fluxes. Resulting stresses and displacements are found explicitly starting from their expressions in terms of a single analytical function. This solution incorporates all speed ranges, including the super-Rayleigh subsonic and intersonic speed regimes, which received no final description to date. Next, under a similar formulation the wedging of an elastic plane is considered for a finite wedge moving at a distance from the crack tip. Finally, we solve the problem for such a wedge moving along the interface of two elastic half-planes compressed together. Considering these problems we determine the driving forces caused by the main underlying factors: the stress field singular points on the contact area (super-Rayleigh subsonic speed regime), the wave radiation (intersonic and supersonic regimes) and the fracture resistance (wedging problem). In addition to the sub-Rayleigh speed regime, where the sliding contact itself gives no contribution to the driving forces, there exists a sharp decrease in the resistance in the vicinity of the longitudinal wave speed with zero limit at this speed.

  19. Multiple pole electromagnetic propulsion system with separated ballistic guidance and electrical current contact surfaces

    DOEpatents

    Sims, Jr., James R.

    2008-07-15

    An electromagnetic propulsion system is disclosed having separate rails for ballistic guidance and for carrying current. In this system, one or more pairs of ballistic guidance rails are provided, with each ballistic guidance rail having a pair of current carrying rails joined to it to form a combined rail. Each combined rail is separated electrically from adjacent combined rails by electrically insulating blocks. Each of the current carrying rails in a given combined rail pair have the same electrical polarity, and the polarities alternate between adjacent combined rails. Armatures contact current carrying rails to complete the circuit to generate the accelerating Lorentz force on the armatures. Bore riders on the sabot and/or projectile are in contact with the ballistic guide rails. Separation of the current carrying and ballistic guidance functions increases resistance of the system to rail movement and bending, as well as reduced wear/damage to the rails. In further embodiments, a circumferential over wrap providing compressive force on the rails further increases resistance of the system to rail movement and bending.

  20. [Contact lens associated dry eye. Current study results and practical implementation].

    PubMed

    Khaireddin, R

    2013-06-01

    Contact lens-associated dry eye symptoms have mostly been therapeutically addressed using artificial tears containing hyaluronic acid to supplement tear film volume with often unsatisfactory results. However, the main reason for contact lens-associated dry eye is not the lack of tear fluid but the lack of tear film stability due to meibomian gland dysfunction leading to reduction of the lipid film of tears. This is associated with increased evaporation of the aqueous phase of tear fluid and a measurable hyperosmolarity of the residual "denatured" tear film. A subsequent inflammatory reaction of the ocular surface then leads to the vicious circle of dry eye. The aim of this review is to summarize current study results on this topic and to give practical advice on how to address dry eye symptoms in contact lens wearers more accurately. For most contact lens-associated dry eye symptoms a combined therapy with unpreserved artificial tears plus phospholipid-liposome eye spray yields the best results. In cases of additional signs of blepharitis the regular use of phospholipid-liposome solution for lid margin hygiene is beneficial.

  1. Current densities and total contact currents during forest clearing tasks under 400 kV power lines.

    PubMed

    Korpinen, Leena; Kuisti, Harri; Elovaara, Jarmo

    2016-09-01

    The aim of the study was to analyze all values of electric currents from measured periods while performing tasks in forest clearing. The objective was also to choose and analyze measurement cases, where current measurements successfully lasted the entire work period (about 30 min). Two forestry workers volunteered to perform four forest clearing tasks under 400 kV power lines. The sampling frequency of the current measurements was 1 sample/s. The maximum values of the current densities were 1.0-1.2 mA/m(2) (calculated internal EFs 5.0-12.0 mV/m), and the average values were 0.2-0.4 mA/m(2) . The highest contact current was 167.4 μA. All measured values during forest clearing tasks were lower than basic restrictions (0.1 V/m and 0.8 V/m) of the International Commission on Non-Ionizing Radiation Protection. Bioelectromagnetics. 37:423-428, 2016. © 2016 The Authors. Bioelectromagnetics published by Wiley Periodicals, Inc.

  2. Solving time-dependent two-dimensional eddy current problems

    NASA Technical Reports Server (NTRS)

    Lee, Min Eig; Hariharan, S. I.; Ida, Nathan

    1988-01-01

    Results of transient eddy current calculations are reported. For simplicity, a two-dimensional transverse magnetic field which is incident on an infinitely long conductor is considered. The conductor is assumed to be a good but not perfect conductor. The resulting problem is an interface initial boundary value problem with the boundary of the conductor being the interface. A finite difference method is used to march the solution explicitly in time. The method is shown. Treatment of appropriate radiation conditions is given special consideration. Results are validated with approximate analytic solutions. Two stringent test cases of high and low frequency incident waves are considered to validate the results.

  3. Photon assisted current in molecular nanojunctions with novel types of contacts

    SciTech Connect

    Fainberg, Boris D.

    2014-03-31

    We propose new approaches to coherent control of transport via molecular junctions, which bypasses several of the hurdles to experimental realization of optically manipulated nanoelectronics noted in the previous literature. The first method is based on the application of intrinsic semiconductor contacts and optical frequencies below the semiconductor bandgap. Our analytical theory predicts a new phenomenon, referred to as coherent destruction of induced tunnelling, which extends the phenomenon of coherent destruction of tunnelling frequently discussed in the previous literature. We also propose to use graphene electrodes as a platform for effective photon assisted tunneling through molecular conduction nanojunctions. We predict dramatic increasing currents evaluated at side-band energies ∼nħω (n is a whole number) related to the modification of graphene gapless spectrum under the action of external electromagnetic field of frequency ω. Our results illustrate the potential of semiconductor and graphene contacts in coherent control of photocurrent.

  4. Bassoonists' medical problems-current state of knowledge.

    PubMed

    Dawson, William J

    2012-06-01

    Specific musical instruments can be a source of physical problems to their players. Based on reviews of the literature and personal experience, this paper summarizes current knowledge of problems affecting musicians who play instruments in the bassoon family (including the bassoon, contrabassoon, and several other instruments). Prevalence rates are higher in reports of surveys (ranging up to 86%), compared to clinical reports of patients seen and treated. Significant risk factors include young age, small body size, female gender, and use of large instruments. Problems unique to bassoonists are rare; most physical difficulties also are seen in general musculoskeletal clinical practices and in musicians playing all types of instruments. The left upper extremity is more commonly affected by overuse-related conditions in bassoonists. Non-playing-related problems are equally important for consideration (such as degenerative disorders and acute trauma), since they also affect practice and performance. Little experimental data exist to validate current and widely-held principles of treatment, rehabilitation, and prevention.

  5. Numerical simulations of the moving contact line problem using a diffuse-interface model

    NASA Astrophysics Data System (ADS)

    Afzaal, Muhammad; Sibley, David; Duncan, Andrew; Yatsyshin, Petr; Duran-Olivencia, Miguel A.; Nold, Andreas; Savva, Nikos; Schmuck, Markus; Kalliadasis, Serafim

    2015-11-01

    Moving contact lines are a ubiquitous phenomenon both in nature and in many modern technologies. One prevalent way of numerically tackling the problem is with diffuse-interface (phase-field) models, where the classical sharp-interface model of continuum mechanics is relaxed to one with a finite thickness fluid-fluid interface, capturing physics from mesoscopic lengthscales. The present work is devoted to the study of the contact line between two fluids confined by two parallel plates, i.e. a dynamically moving meniscus. Our approach is based on a coupled Navier-Stokes/Cahn-Hilliard model. This system of partial differential equations allows a tractable numerical solution to be computed, capturing diffusive and advective effects in a prototypical case study in a finite-element framework. Particular attention is paid to the static and dynamic contact angle of the meniscus advancing or receding between the plates. The results obtained from our approach are compared to the classical sharp-interface model to elicit the importance of considering diffusion and associated effects. We acknowledge financial support from European Research Council via Advanced Grant No. 247031.

  6. Evaluation of the energy barrier for failure of Au atomic contact based on temperature dependent current-voltage characteristics.

    PubMed

    Aiba, Akira; Kaneko, Satoshi; Fujii, Shintaro; Nishino, Tomoaki; Kiguchi, Manabu

    2016-08-01

    We investigated the mechanical stability of single gold atomic contacts at an applied bias voltage of 0-1 V using a nano-fabricated mechanically controllable break junction technique at 300-400 K under ambient conditions. The single atomic contact shows the quantized conductance (G0 = 2e(2)/h) and can carry considerably large current, which results in the current-induced failure of the contact. The contact failure behaviour under the applied bias conditions was studied by statistical analysis of the current-voltage (I-V) curves of the single Au contacts. We demonstrated that, at the elevated temperature of 300-400 K, the current-induced local heating effect is negligibly small and current-induced forces in the contact are responsible for the observed failure of the single gold contacts under the high bias voltage conditions (>0.4 V). Furthermore, based on the temperature dependence of the contact failure behaviour in the I-V curves, the energy barrier of the contact-failure was evaluated to be ca. 0.1 V. PMID:27427285

  7. Contact resistance problems applying ERT on low bulk density forested stony soils. Is there a solution?

    NASA Astrophysics Data System (ADS)

    Deraedt, Deborah; Touzé, Camille; Robert, Tanguy; Colinet, Gilles; Degré, Aurore; Garré, Sarah

    2015-04-01

    Electrical resistivity tomography (ERT) has often been put forward as a promising tool to quantify soil water and solute fluxes in a non-invasive way. In our experiment, we wanted to determine preferential flow processes along a forested hillslope using a saline tracer with ERT. The experiment was conducted in the Houille watershed, subcatchment of the Meuse located in the North of Belgian Ardennes (50° 1'52.6'N, 4° 53'22.5'E). The climate is continental but the soil under spruce (Picea abies (L.) Karst.) and Douglas fire stand (Pseudotsuga menziesii (Mirb.) Franco) remains quite dry (19% WVC in average) during the whole year. The soil is Cambisol and the parent rock is Devonian schist covered with variable thickness of silty loam soil. The soil density ranges from 1.13 to 1.87 g/cm3 on average. The stone content varies from 20 to 89% and the soil depth fluctuates between 70 and 130 cm. The ERT tests took place on June 1st 2012, April 1st, 2nd and 3rd 2014 and May 12th 2014. We used the Terrameter LS 12 channels (ABEM, Sweden) in 2012 test and the DAS-1 (Multi-Phase Technologies, United States) in 2014. Different electrode configurations and arrays were adopted for different dates (transect and grid arrays and Wenner - Schlumberger, Wenner alpha and dipole-dipole configurations). During all tests, we systematically faced technical problems, mainly related to bad electrode contact. The recorded data show values of contact resistance above 14873 Ω (our target value would be below 3000 Ω). Subsequently, we tried to improve the contact by predrilling the soil and pouring water in the electrode holes. The contact resistance improved to 14040 Ω as minimum. The same procedure with liquid mud was then tested to prevent quick percolation of the water from the electrode location. As a result, the lower contact resistance dropped to 11745 Ω. Finally, we applied about 25 litre of saline solution (CaCl2, 0.75g/L) homogeneously on the electrode grid. The minimum value of

  8. Inverse problem for the current loop model: Possibilities and restrictions

    NASA Astrophysics Data System (ADS)

    Demina, I. M.; Farafonova, Yu. G.

    2016-07-01

    The possibilities of determining arbitrary current loop parameters based on the spatial structures of the magnetic field components generated by this loop on a sphere with a specified radius have been considered with the use of models. The model parameters were selected such that anomalies created by current loops on a sphere with a radius of 6378 km would be comparable in value with the different-scale anomalies of the observed main geomagnetic field (MGF). The least squares method was used to solve the inverse problem. Estimates close to the specified values were obtained for all current loop parameters except the current strength and radius. The radius determination error can reach ±120 km; at the same time, the magnetic moment value is determined with an accuracy of ±1%. The resolvability of the current force and radius can to a certain degree be improved by decreasing the observation sphere radius such that the ratio of the source distance to the current loop radius would be at least smaller than eight, which can be difficult to reach when modeling MGF.

  9. Effect of interfacial oxide layers on the current-voltage characteristics of Al-Si contacts

    NASA Technical Reports Server (NTRS)

    Porter, W. A.; Parker, D. L.

    1976-01-01

    Aluminum-silicon contacts with very thin interfacial oxide layers and various surface impurity concentrations are studied for both n and p-type silicon. To determine the surface impurity concentrations on p(+)-p and n(+)-n structures, a modified C-V technique was utilized. Effects of interfacial oxide layers and surface impurity concentrations on current-voltage characteristics are discussed based on the energy band diagrams from the conductance-voltage plots. The interfacial oxide and aluminum layer causes image contrasts on X-ray topographs.

  10. Mechanism of the polarization control in intracavity- contacted VCSEL with rhomboidal oxide current aperture

    NASA Astrophysics Data System (ADS)

    Bobrov, M. A.; Maleev, N. A.; Blokhin, S. A.; Kuzmenkov, A. G.; Vasil'ev, A. P.; Blokhin, A. A.; Kulagina, M. M.; Guseva, Yu A.; Troshkov, S. I.; Ustinov, V. M.

    2016-08-01

    The possible mechanisms of the polarization control in single-mode intracavity- contacted vertical-cavity surface-emitting lasers (IC-VCSELs) with the rhomboidal selectively- oxidized current aperture were investigated. It was found that the lasing emission polarization of all single-mode VCSELs is fixed along the minor diagonal of the rhomboidal-shape aperture (the [110] direction). Numerical modelling of carrier transport did not reveal any sufficient injection anisotropy in the laser active region, while the transverse optical confinement factors calculated for the fundamental mode with two orthogonal polarizations are identical. Optical loss anisotropy and/or gain anisotropy are the most likely mechanisms of inducing the polarization fixation.

  11. An Equivalent Circuit Modeling of Discharge Current Injected in Contact with an ESD-gun

    NASA Astrophysics Data System (ADS)

    Fujiwara, Osamu; Tanaka, Hideyuki; Yamanaka, Yukio

    The transient electromagnetic (EM) fields caused by an electrostatic discharge (ESD) have broadband frequency spectra, which cause serious failure to high-tech information equipment. From this perspective, an ESD testing for the EM immunity of the equipment is specified by the IEC 61000-4-2, in which the detailed waveform of the discharge current injected onto the IEC recommended Pellegrini target in contact with an ESD-gun is prescribed for calibration. However, the factors for determining the current waveform remain unclear, and thus the IEC prescribed current waveform is unlikely to be injected into actual equipment. In this study, based on the structure of an ESD-gun, an equivalent circuit modeling is proposed for analyzing the discharge current injected onto a 50-Ω SMA connector instead of the IEC target that has frequency-dependent transmission characteristics. Its validity is confirmed by comparing the calculated current waveform with the measured result. The proposed circuit modeling is also validated from measurement of the discharge current injected onto a transmission-line by the ESD-gun.

  12. Designer switches: Effect of contact geometry on the transient current of a strongly correlated quantum dot

    NASA Astrophysics Data System (ADS)

    Goker, Ali Ihsan; Zhu, Zhiyong; Schwingenschlogl, Udo; Manchon, Aurelien

    2011-03-01

    The time-dependent non-crossing approximation is utilized to investigate the influence of the geometry of contacts made of gold on time dependent current through a quantum dot suddenly shifted into the Kondo regime via a gate voltage. For an asymmetrically coupled system, instantaneous conductance exhibits complex fluctuations. We identify the frequencies participating in these fluctuations and they turn out to be proportional to the separation between the sharp features in the density of states and the Fermi level. Increasing ambient temperature or bias quenches the amplitude of these fluctuations. This suggests that the interference between the emerging Kondo resonance and the van Hove singularities in the density of states is the underlying microscopic mechanism for these fluctuations. Based on these observations, we predict that using different electrode geometries would give rise to drastically different transient currents which can be accessed with state-of-the-art ultrafast pump-probe techniques. King Abdullah University of Science and Technology.

  13. Solving time-dependent two-dimensional eddy current problems

    NASA Technical Reports Server (NTRS)

    Lee, Min Eig; Hariharan, S. I.; Ida, Nathan

    1990-01-01

    Transient eddy current calculations are presented for an EM wave-scattering and field-penetrating case in which a two-dimensional transverse magnetic field is incident on a good (i.e., not perfect) and infinitely long conductor. The problem thus posed is of initial boundary-value interface type, where the boundary of the conductor constitutes the interface. A potential function is used for time-domain modeling of the situation, and finite difference-time domain techniques are used to march the potential function explicitly in time. Attention is given to the case of LF radiation conditions.

  14. FCL: A solution to fault current problems in DC networks

    NASA Astrophysics Data System (ADS)

    Cointe, Y.; Tixador, P.; Villard, C.

    2008-02-01

    Within the context of the electric power market liberalization, DC networks have many interests compared to AC ones. New energy landscapes open the way of a diversified production. Innovative interconnection diagrams, in particular using DC buses, are under development. In this case it is not possible to defer the fault current interruption in the AC side. DC fault current cutting remains a difficult problem. FCLs (Fault Current Limiters) enable to limit the current to a preset value, lower than the theoretical short-circuit current. For this application Coated Conductors (CC) offer an excellent opportunity. Due to these promising characteristics we build a test bench and work on the implementation of these materials. The test bench is composed by 10 power amplifiers, to reach 4 kVA in many configurations of current and voltage. We carried out limiting experiments on DyBaCuO CC from EHTS, samples are about five centimeters long and many potential measuring points are pasted on the shunt to estimate the quench homogeneity. Thermal phenomena in FCLs are essential, numerical models are important to calculate the maximum temperatures. To validate these models we measure the CC temperature by depositing thermal sensors (Cu resistance) above the shunt layer and the substrate. An electrical insulation with a low thermal resistivity between the CC and the sensors is necessary. We use a thin layer of Parylene because of its good mechanical and electrical insulation properties at low temperature. The better quench behaviour of CC for temperatures close to the critical temperature has been confirmed. The measurements are in good agreement with simulations, this validates the thermal models.

  15. The Use of Contact Lenses in Industrial Environments: An Assessment of Current Research and Policy.

    ERIC Educational Resources Information Center

    Connors, Terry

    2001-01-01

    Attempts to dispel rumors concerning contact lenses and tries to supply prudent-use practices for allowing contact lenses in industry and laboratories. Discusses federal regulations that impact the use of contact lenses in industry, policy statements from medical organizations on use of contact lenses in industrial environments, and the…

  16. [New image of occupational medicine--current problems, future solutions].

    PubMed

    Andrzejak, Ryszard; Beck, Bogusław; Urban, Joanna

    2006-01-01

    Current problems in occupational medicine result mainly from the situation in which existing structures are not appropriately adapted to the changes in economy, work market structures and social and demographic trends, which rapidly appeared within the last decade. The Act of Occupational Medicine Service in force precisely defines the duties of occupational medicine services. However, although the legal powers seem clear and detailed, the possibility of real actions is not put in order and encounters many barriers. The changes in structures of economy, enterprises and work market result in the situation in which despite the obligatory preventive examination system, there is a large group of people that are not subject to them. Care of workers in bigger companies or institutions is also the source of problems concerning mainly the examination range, but also the identification of new threats connected with ergonomics, psychological or biological factors; their limiting, monitoring and prevention. A broad issue of provided service qualities is closely connected with the problems mentioned above. Another question is defining the quality control system, the execution of post-control suggestions and the possibility of applying possible sanctions. A significant task is also to modify the examining and specialisation acquirement system. In the creation of the new image of occupational medicine in Poland the most significant issue is to correct the current legal grounds by introducing new standards of health protection for working people, enable to provide high- quality services, create the conditions for functioning of multidiscipline teams preventively caring of working people, being a guarantee of health and economic benefits for the society.

  17. Inflammatory bowel diseases: Current problems and future tasks.

    PubMed

    Actis, Giovanni C; Pellicano, Rinaldo; Rosina, Floriano

    2014-08-01

    Current knowledge on inflammatory bowel disease (IBD) is mainly endorsed by controlled trials and epidemiologic studies. Yet, we seldom look at the messages from real-world practice. Among a patient population followed since 2008, we looked at an unselected sample of 64 IBD patients [26 Crohn's disease (CD) and 38 ulcerative colitis (UC)] who had been seen as out-patients in the last year. Inducing remission, mesalamines (86% for UC/69% for CD/33%-16% as MMX formulation) prevailed as prescriptions; steroids (55%/19% for UC/CD) ranked second. Prescription of third-party drugs (antibiotics, NSAIDs, biologics) and adherence, were issues in the maintenance. 34% of CD, and 23% of UC patients showed accompanying immunologic diseases: CD-associated familiar psoriasis (4:9) ranked first. Main Message. The association between IBD (CD mainly) and psoriasis, now found in our practice, matches current basic science gathering IBD together with psoriasis (and perhaps chronic respiratory disease) under the comprehensive term "barrier organ disease" wherein an epithelial surface with sensor systems rules contacts between outer antigens and a reactive underneath tissue, with the balance between inflammation and quiescence kept at any time by mucosal permeability. IBD is thus viewed as a polyfactorial/polygenic/syndromic disorder, embedded into a galaxy of immune conditions offering multiple points of attack. This mindset of splitting the IBDs into pathogenic categories may allow overcoming the uniformly targeting of a single cytokine by biological drugs, in favor of demarcating the boundaries between different disease-subtype-specific indications, and paving the way to future personalized strategies. PMID:25133045

  18. Emotional/Behavioral Difficulties and Mental Health Service Contacts of Students in Special Education for Non-Mental Health Problems

    ERIC Educational Resources Information Center

    Pastor, Patricia N.; Reuben, Cynthia A.

    2009-01-01

    Background: Emotional/behavioral difficulties and mental health (MH) service contacts of 3 groups of youth were compared: students in special education for non-MH problems, students in special education for MH problems, and youth not in special education. Methods: Parents reported the characteristics, special education placement,…

  19. Inverse problem of pulsed eddy current field of ferromagnetic plates

    NASA Astrophysics Data System (ADS)

    Chen, Xing-Le; Lei, Yin-Zhao

    2015-03-01

    To determine the wall thickness, conductivity and permeability of a ferromagnetic plate, an inverse problem is established with measured values and calculated values of time-domain induced voltage in pulsed eddy current testing on the plate. From time-domain analytical expressions of the partial derivatives of induced voltage with respect to parameters, it is deduced that the partial derivatives are approximately linearly dependent. Then the constraints of these parameters are obtained by solving a partial linear differential equation. It is indicated that only the product of conductivity and wall thickness, and the product of relative permeability and wall thickness can be determined accurately through the inverse problem with time-domain induced voltage. In the practical testing, supposing the conductivity of the ferromagnetic plate under test is a fixed value, and then the relative variation of wall thickness between two testing points can be calculated via the ratio of the corresponding inversion results of the product of conductivity and wall thickness. Finally, this method for wall thickness measurement is verified by the experiment results of a carbon steel plate. Project supported by the National Defense Basic Technology Research Program of China (Grant No. Z132013T001).

  20. Conversion disorder: current problems and potential solutions for DSM-5.

    PubMed

    Stone, Jon; LaFrance, W Curt; Brown, Richard; Spiegel, David; Levenson, James L; Sharpe, Michael

    2011-12-01

    Conversion disorder in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) describes neurological symptoms, including weakness, numbness and events resembling epilepsy or syncope, which can be positively identified as not being due to recognised neurological disease. This review combines perspectives from psychiatry, psychology and neurology to identify and discuss key problems with the current diagnostic DSM-IV criteria for conversion disorder and to make the following proposals for DSM-5: (a) abandoning the label "conversion disorder" and replacing it with an alternative term that is both theoretically neutral and potentially more acceptable to patients and practitioners; (b) relegating the requirements for "association of psychological factors" and the "exclusion of feigning" to the accompanying text; (c) adding a criterion requiring clinical findings of internal inconsistency or incongruity with recognised neurological or medical disease and altering the current 'disease exclusion' criteria to one in which the symptom must not be 'better explained' by a disease if present, (d) adding a 'cognitive symptoms' subtype. We also discuss whether conversion symptoms are better classified with other somatic symptom disorders or with dissociative disorders and how we might address the potential heterogeneity of conversion symptoms in classification.

  1. Theory of Cooper-pair mass spectroscopy by the current-induced contact-potential difference

    SciTech Connect

    Mishonov, T.M. )

    1994-08-01

    The creation of contactless Cooper-pair mass spectroscopy based on the Bernoulli-Venturi effect in thin superconducting films is suggested. The preparation of layered metal-insulator-superconductor-type heterostructures and standard electronics are necessary for the realization of the method. Two electrodes are patterned from the metallic layer: a circle and concentric-ring electrode. The currents in the superconducting film are induced by a drive coil concentric to the electrodes. The Bernoulli potential of the charged Cooper-pair superfluid creates a measurable electric polarization of gate electrodes of this plane-capacitor device. The current-induced contact-potential difference is limited by the Ginzburg-Landau potential [minus][ital a][sub GL]([ital T])= 1/2[h bar][ital e][sup *][ital H][sub [ital c]2]([ital T])/[ital m][sup *][ital c]=[h bar][sup 2]/2[ital m][sup *][xi][sup 2]([ital T]). The additional charge of the polarized circular electrode has the same sign as the free charge carriers of the superconductor.

  2. Deformation of contact surfaces in a vacuum interrupter after high-current interruptions

    NASA Astrophysics Data System (ADS)

    Wang, Haoran; Wang, Zhenxing; Zhou, Zhipeng; Jiang, Yanjun; Wang, Jianhua; Geng, Yingsan; Liu, Zhiyuan

    2016-08-01

    In a high-current interruption, the contact surface in a vacuum interrupter might be severely damaged by constricted vacuum arcs causing a molten area on it. As a result, a protrusion will be initiated by a transient recovery voltage after current zero, enhancing the local electric field and making breakdowns occur easier. The objective of this paper is to simulate the deformation process on the molten area under a high electric field by adopting the finite element method. A time-dependent Electrohydrodynamic model was established, and the liquid-gas interface was tracked by the level-set method. From the results, the liquid metal can be deformed to a Taylor cone if the applied electric field is above a critical value. This value is correlated to the initial geometry of the liquid metal, which increases as the size of the liquid metal decreases. Moreover, the buildup time of a Taylor cone obeys the power law t = k × E-3, where E is the initial electric field and k is a coefficient related to the material property, indicating a temporal self-similar characteristic. In addition, the influence of temperature has little impact on the deformation but has great impact on electron emission. Finally, the possible reason to initiate a delayed breakdown is associated with the deformation. The breakdown does not occur immediately when the voltage is just applied upon the gap but is postponed to several milliseconds later when the tip is formed on the liquid metal.

  3. Power counting of contact-range currents in effective field theory.

    PubMed

    Valderrama, M Pavón; Phillips, D R

    2015-02-27

    We analyze the power counting of two-body currents in nuclear effective field theories (EFTs). We find that the existence of nonperturbative physics at low energies, which is manifest in the existence of the deuteron and the ^{1}S_{0} NN virtual bound state, combined with the appearance of singular potentials in versions of nuclear EFT that incorporate chiral symmetry, modifies the renormalization-group flow of the couplings associated with contact operators that involve nucleon-nucleon pairs and external fields. The order of these couplings is thereby enhanced with respect to the naive-dimensional-analysis estimate. Consequently, short-range currents enter at a lower order in the chiral EFT than has been appreciated up until now, and their impact on low-energy observables is concomitantly larger. We illustrate the changes in the power counting with a few low-energy processes involving external probes and few-nucleon systems, including electron-deuteron elastic scattering and radiative neutron capture by protons.

  4. The influence of small impurity additions and direct electric current on the kinetics of contact melting in metals

    NASA Astrophysics Data System (ADS)

    Ahkubekov, A. A.; Ahkubekova, S. N.; Enaldieva, O. L.; Orkvasov, T. A.; Sozaev, V. A.

    2008-02-01

    Using the experimental data on contact melting of polycrystalline indium, tin and lead - based solid solutions with low-melting alloys we show that besides the diffusive, adhesive and low - dimensional mechanisms of contact melting it is necessary to take into account the segregational mechanism as well. The surfaces of a contact between the polycrystalline solid solutions and low - melting metals enrich in lower melting components due to the grain-boundary and surface segregation. One can influence on the kinetics of contact melting using alkali metals as impurity additives and applying the direct electric current. For example, the sodium addition to indium results in 3 times expansion of contact layer in the (In + 0.1 at. % Na) - Bi system, but in 2 times shrinking of that layer in the (In + 0.1 at. % Na) - Cd system in comparison to experiments without impurities.

  5. Experimental evidence of direct contact formation for the current transport in silver thick film metallized silicon emitters

    NASA Astrophysics Data System (ADS)

    Cabrera, Enrique; Olibet, Sara; Glatz-Reichenbach, Joachim; Kopecek, Radovan; Reinke, Daniel; Schubert, Gunnar

    2011-12-01

    Great advances have been achieved in the development of silver pastes. The use of smaller silver particles, higher silver content, and, thus, less glass frit allow modern silver pastes to contact high resistive emitters without the necessity of a selective emitter or subsequent plating. To identify the microscopic key reasons behind the improvement of silver paste, it is essential to understand the current transport mechanism from the silicon emitter into the bulk of the silver finger. Two current transport theories predominate: i) The current flows through the Ag crystallites grown into the Si emitter, which are separated by a thin glass layer or possibly in direct contact with the silver finger. ii) The current is transported by means of multistep tunneling into the silver finger across nano-Ag colloids in the glass layer, which are formed at optimal firing conditions; the formation of Ag crystallites into the Si surface is synonymous with over-firing. In this study, we contact Si solar cell emitters with different silver pastes on textured and flat silicon surfaces. A sequential selective silver-glass etching process is employed to expose and isolate the different contact components for current transport. The surface configurations after the etching sequences are observed with scanning electron microscopy. Liquid conductive silver is then applied to each sample and the contact resistivity is measured to determine the dominant microscopic conduction path system. We observe glass-free emitter areas at the tops of the pyramidal-textured Si that lead to the formation of direct contacts between the Ag crystallites grown into the Si emitter and the bulk of the silver finger. We present experimental evidence that the major current flow into the silver finger is through these direct contacts.

  6. Nonlinear time-series analysis of current signal in cathodic contact glow discharge electrolysis

    NASA Astrophysics Data System (ADS)

    Allagui, Anis; Rojas, Andrea Espinel; Bonny, Talal; Elwakil, Ahmed S.; Abdelkareem, Mohammad Ali

    2016-05-01

    In the standard two-electrode configuration employed in electrolytic process, when the control dc voltage is brought to a critical value, the system undergoes a transition from conventional electrolysis to contact glow discharge electrolysis (CGDE), which has also been referred to as liquid-submerged micro-plasma, glow discharge plasma electrolysis, electrode effect, electrolytic plasma, etc. The light-emitting process is associated with the development of an irregular and erratic current time-series which has been arbitrarily labelled as "random," and thus dissuaded further research in this direction. Here, we examine the current time-series signals measured in cathodic CGDE configuration in a concentrated KOH solution at different dc bias voltages greater than the critical voltage. We show that the signals are, in fact, not random according to the NIST SP. 800-22 test suite definition. We also demonstrate that post-processing low-pass filtered sequences requires less time than the native as-measured sequences, suggesting a superposition of low frequency chaotic fluctuations and high frequency behaviors (which may be produced by more than one possible source of entropy). Using an array of nonlinear time-series analyses for dynamical systems, i.e., the computation of largest Lyapunov exponents and correlation dimensions, and re-construction of phase portraits, we found that low-pass filtered datasets undergo a transition from quasi-periodic to chaotic to quasi-hyper-chaotic behavior, and back again to chaos when the voltage controlling-parameter is increased. The high frequency part of the signals is discussed in terms of highly nonlinear turbulent motion developed around the working electrode.

  7. Advanced Curation: Solving Current and Future Sample Return Problems

    NASA Technical Reports Server (NTRS)

    Fries, M.; Calaway, M.; Evans, C.; McCubbin, F.

    2015-01-01

    Advanced Curation is a wide-ranging and comprehensive research and development effort at NASA Johnson Space Center that identifies and remediates sample related issues. For current collections, Advanced Curation investigates new cleaning, verification, and analytical techniques to assess their suitability for improving curation processes. Specific needs are also assessed for future sample return missions. For each need, a written plan is drawn up to achieve the requirement. The plan draws while upon current Curation practices, input from Curators, the analytical expertise of the Astromaterials Research and Exploration Science (ARES) team, and suitable standards maintained by ISO, IEST, NIST and other institutions. Additionally, new technologies are adopted on the bases of need and availability. Implementation plans are tested using customized trial programs with statistically robust courses of measurement, and are iterated if necessary until an implementable protocol is established. Upcoming and potential NASA missions such as OSIRIS-REx, the Asteroid Retrieval Mission (ARM), sample return missions in the New Frontiers program, and Mars sample return (MSR) all feature new difficulties and specialized sample handling requirements. The Mars 2020 mission in particular poses a suite of challenges since the mission will cache martian samples for possible return to Earth. In anticipation of future MSR, the following problems are among those under investigation: What is the most efficient means to achieve the less than 1.0 ng/sq cm total organic carbon (TOC) cleanliness required for all sample handling hardware? How do we maintain and verify cleanliness at this level? The Mars 2020 Organic Contamination Panel (OCP) predicts that organic carbon, if present, will be present at the "one to tens" of ppb level in martian near-surface samples. The same samples will likely contain wt% perchlorate salts, or approximately 1,000,000x as much perchlorate oxidizer as organic carbon

  8. Current-phase relation and h /e -periodic critical current of a chiral Josephson contact between one-dimensional Majorana modes

    NASA Astrophysics Data System (ADS)

    Shapiro, Dmitriy S.; Shnirman, Alexander; Mirlin, Alexander D.

    2016-04-01

    We explore a long Josephson contact transporting Cooper pairs between one-dimensional (1D) charge-neutral chiral Majorana modes in the leads via charged Dirac chiral modes in the normal region. We investigate the regimes of (i) transparent contacts and (ii) tunnel junctions implemented in 3D topological insulator/superconductor/magnet hybrid structures. The setup acts as a SQUID controlled by the magnetic flux enclosed by the chiral loop of the normal region. This chirality leads to the fractional h /e -periodic pattern of critical current. The current-phase relation can have sawtoothlike shape with spikes at unusual even phases of 2 π n .

  9. Contact Precautions for Multidrug-Resistant Organisms (MDROs): Current Recommendations and Actual Practice

    PubMed Central

    Clock, Sarah A.; Cohen, Bevin; Behta, Maryam; Ross, Barbara; Larson, Elaine L.

    2009-01-01

    Background Contact precautions are recommended for interactions with patients colonized/infected with multidrug-resistant organisms; however, rates of contact precautions practice are unknown. Methods Observers recorded the availability of supplies and staff/visitor adherence to contact precautions at rooms of patients indicated for contact precautions. Data were collected at three sites in a New York City hospital network. Results Contact precautions signs were present for 85.4% of indicated patients. The largest proportions were indicated for isolation for vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus cultures. Isolation carts were available outside 93.7-96.7% of rooms displaying signs, and personal protective equipment was available at rates of 49.4-72.1% for gloves (all sizes: small, medium, and large) and 91.7-95.2% for gowns. Overall adherence rates upon room entry and exit, respectively, were 19.4% and 48.4% for hand hygiene, 67.5% and 63.5% for gloves, and 67.9% and 77.1% for gowns. Adherence was significantly better in intensive care units (p<0.05) and by patient-care staff (p<0.05), and patient-care staff compliance with one contact precautions behavior was predictive of adherence to additional behaviors (p<0.001). Conclusions Our findings support the recommendation that methods to monitor contact precautions and identify and correct non-adherent practices should be a standard component of infection prevention and control programs. PMID:19913329

  10. Some Current Problems in Simulator Design, Testing and Use.

    ERIC Educational Resources Information Center

    Caro, Paul W.

    Concerned with the general problem of the effectiveness of simulator training, this report reflects information developed during the conduct of aircraft simulator training research projects sponsored by the Air Force, Army, Navy, and Coast Guard. Problems are identified related to simulator design, testing, and use, all of which impact upon…

  11. [Current problems in psychiatric health care in Poland (2005)].

    PubMed

    Puzyński, Stanisław; Langiewicz, Wanda; Pietrzykowska, Bozena

    2006-01-01

    The paper is a presentation of the most important and actual psychiatric health care problems in Poland: the financial situation of hospitals, the risk faced by the out-patient psychiatric care,ethical problems related to clinical practice, as well as issues on postgraduate education.

  12. Contact problem for an elastic reinforcement bonded to an elastic plate

    NASA Technical Reports Server (NTRS)

    Erdogan, F.; Civelek, M. B.

    1973-01-01

    The stiffening layer is treated as an elastic membrane and the base plate is assumed to be an elastic continuum. The bonding between the two materials is assumed to be either one of direct adhesion ro through a thin adhesive layer which is treated as a shear spring. The solution for the simple case in which both the stiffener and the base plate are treated as membranes is also given. The contact stress is obtained for a series of numerical examples. In the direct adhesion case the contact stress becomes infinite at the stiffener ends with a typical square root singularity for the continuum model, and behaving as a delta function for the membrane model. In the case of bonding through an adhesive layer the contact stress becomes finite and continuous along the entire contact area.

  13. Differentiation of the functional in an optimization problem for diffusion and convective transfer coefficients of elliptic imperfect contact interface problems

    NASA Astrophysics Data System (ADS)

    Manapova, Aigul

    2016-08-01

    We consider optimal control problems for second order elliptic equations with non-self-adjoint operators-convection-diffusion problems. Control processes are described by semi-linear convection-diffusion equation with discontinuous data and solutions (states) subject to the boundary interface conditions of imperfect type (i.e., problems with a jump of the coefficients and the solution on the interface; the jump of the solution is proportional to the normal component of the flux). Controls are involved in the coefficients of diffusion and convective transfer. We prove differentiability and Lipshitz continuity of the cost functional, depending on a state of the system and a control. The calculation of the gradients uses the numerical solutions of direct problems for the state and adjoint problems.

  14. An automatic contact algorithm in DYNA3D for impact problems

    SciTech Connect

    Whirley, R.G.; Engelmann, B.E.

    1993-07-23

    This paper presents a new approach for the automatic definition and treatment of mechanical contact in explicit nonlinear finite element analysis. Automatic contact offers the benefits of significantly reduced model construction time and fewer opportunities for user error, but faces significant challenges in reliability and computational costs. Key aspects of the proposed new method include automatic identification of adjacent and opposite surfaces in the global search phase, and the use of a well-defined surface normal which allows a consistent treatment of shell intersection and corner contact conditions without a ad-hoc rules. The paper concludes with three examples which illustrate the performance of the newly proposed algorithm in the public DYNA3D code.

  15. A technique to form a porous silicon layer with no backside contact by alternating current electrochemical process

    NASA Astrophysics Data System (ADS)

    El-Bahar, A.; Nemirovsky, Y.

    2000-07-01

    We report here the formation of porous silicon under alternating current conditions. Instead of applying the usual direct current electrochemical process, an alternating current was applied with a given frequency and peak voltage. The porous silicon layer properties are equivalent to the properties that would be achieved by the standard direct current formation technique (i.e., same porosity level). The main advantages of this process are: (a) The alternating current formed porous silicon exhibits higher mechanical stability during the drying step than layers formed using the standard direct current technique. (b) The alternating current process can be performed without a deposited backside contact. These simplify the process and permit its integration with high temperature processing steps and clean furnaces of a modern very large sale-integrated technology.

  16. Current State and Problems of Higher Education Reform

    ERIC Educational Resources Information Center

    Salnikov, N.; Burukhin, S.

    2009-01-01

    Higher education in Russia is experiencing changes in curriculum and in the specialization and function of institutions in the search for a better model for a post-Soviet society. The early 1990s saw the start of the reform of the system of education in Russia. However, problems of quality and of continuity with secondary education have still not…

  17. Differential Item Functioning (DIF): Current Problems and Future Directions

    ERIC Educational Resources Information Center

    Karami, Hossein; Salmani Nodoushan, Mohammad Ali

    2011-01-01

    With the rising concerns over the fairness of language tests, Differential Item Functioning (DIF) has been increasingly applied in bias analysis. Despite its widespread use in psychometric circles, DIF is facing a number of serious problems. This paper is an attempt to shed light on a number of the issues involved in DIF analysis. Specifically,…

  18. CHAPTER 10: CURRENT TECHNICAL PROBLEMS IN EMERGY ANALYSIS

    EPA Science Inventory

    Technical problems related to the determination of the emergy base for self-organization in environmental systems are considered in this paper. The comparability of emergy analysis results depends on emergy analysts making similar choices in determining the emergy base for a part...

  19. Kinematics and tribological problems of linear guidance systems in four contact points

    NASA Astrophysics Data System (ADS)

    Popescu, A.; Olaru, D.

    2016-08-01

    A procedure has been developed to determine both the value of the ball's angular velocity and the angular position of this velocity, according to the normal loads in a linear system with four contact points. The program is based on the variational analysis of the power losses in ball-races contacts. Based on this the two kinematics parameters of the ball (angular velocity and angular position) were determined, in a linear system type KUE 35 as function of the C/P ratio.

  20. Asymmetrically contacted germanium photodiode using a metal-interlayer-semiconductor-metal structure for extremely large dark current suppression.

    PubMed

    Zang, Hwan-Jun; Kim, Gwang-Sik; Park, Gil-Jae; Choi, Yong-Soo; Yu, Hyun-Yong

    2016-08-15

    In this study, we proposed germanium (Ge) metal-interlayer-semiconductor-metal (MISM) photodiodes (PD), with an anode of a metal-interlayer-semiconductor (MIS) contact and a cathode of a metal-semiconductor (MS) contact, to efficiently suppress the dark current of Ge PD. We selected titanium dioxide (TiO2) as an interlayer material for the MIS contact, due to its large valence band offset and negative conduction band offset to Ge. We significantly suppress the dark current of Ge PD by introducing the MISM structure with a TiO2 interlayer, as this enhances the hole Schottky barrier height, and thus acts as a large barrier for holes. In addition, it collects photo-generated carriers without degradation, due to its negative conduction band offset to Ge. This reduces the dark current of Ge MISM PDs by ×8000 for 7-nm-thick TiO2 interlayer, while its photo current is still comparable to that of Ge metal-semiconductor-metal (MSM) PDs. Furthermore, the proposed Ge PD shows ×6,600 improvement of the normalized photo-to-dark-current ratio (NPDR) at a wavelength of 1.55 μm. The proposed Ge MISM PD shows considerable promise for low power and high sensitivity Ge-based optoelectronic applications. PMID:27519063

  1. [Current problems in the use of probation with compulsory work].

    PubMed

    Salautdinov, S A

    1976-01-01

    In the framework of the Soviet law, probation accompanied by compulsory work represents an up-to-date measure of a criminal character that allows to rehabilitate a convicted offender without depriving him of his freedom. The Panfederal Institute for the study of the causes of criminal behaviour and for the formulation of measures for preventing it, has conducted a number of researches directed at clearing up some debated problems bearing on the implementation of the measures existing on the subject, and at collecting proposals of amendment. The present article deals with the assumptions and preconditions, of both an objective and subjective character, underlying the application of this juridical institute, and also tackles, by referring to some cases previously occurred, the problems posed by the various types of subjects. Special attention is devoted to the decision-making procedure followed by the tribunals in applying the said measures, and to the various elements on which it is to be based.

  2. Scale bridging in molecular simulation. Recurrent problems and current options

    NASA Astrophysics Data System (ADS)

    Hartmann, Carsten; Delle Site, Luigi

    2015-09-01

    Multiscale and multiphysics approaches have become an integral part of the molecular modeling and simulation toolbox and are used to attack various real-world problems that would be out of reach without these techniques. This special topics issue is devoted to a critical appraisal of some of the most popular scale bridging techniques for molecular simulation. It features regular articles and a "Discussion and Debate" section, in which experts in the field discuss specific articles and general aspects of scale bridging techniques.

  3. Current Problems in X-Ray Emission Spectroscopy

    NASA Technical Reports Server (NTRS)

    Goldstein, Joseph I.; Williams, David B.; Lyman, Charles E.

    1989-01-01

    Various problems that limit X-ray analysis in the analytical electron microscope are reviewed. Major emphasis is given to the trade-off between minimum mass fraction and spatial resolution. New developments such as high-brightness electron guns, new X-ray spectrometers and clean high-vacuum analysis conditions will lead to major improvements in the accuracy and detectability limits of X-ray emission spectroscopy.

  4. Unsolved problems in biology--The state of current thinking.

    PubMed

    Dev, Sukhendu B

    2015-03-01

    Many outstanding problems have been solved in biology and medicine for which scientists have been awarded prestigious prizes including the Nobel Prize, Lasker Award and Breakthrough Prizes in life sciences. These have been the fruits of years of basic research. From time to time, publications have appeared listing "unsolved" problems in biology. In this article, I ask the question whether it is possible to have such a list, if not a unique one, at least one that is analogous to the Millennium Prize in mathematics. My approach to finding an answer to this question was to gather views of leading biologists. I have also included my own views. Analysis of all the responses received over several years has convinced me that it is difficult, but not impossible, to have such a prize. Biology is complex and very interdisciplinary these days at times involving large numbers of teams, unlike mathematics, where Andrew Wiles spent seven years in complete isolation and secrecy solving Fermat's last theorem. Such an approach is simply not possible in biology. Still I would like to suggest that a similar prize can be established by a panel of distinguished scientists. It would be awarded to those who solved one of the listed problems in biology that warrant a verifiable solution. Despite many different opinions, I found that there is some commonality in the responses I received - I go on to discuss what these are and how they may impact future thinking.

  5. Unsolved problems in biology--The state of current thinking.

    PubMed

    Dev, Sukhendu B

    2015-03-01

    Many outstanding problems have been solved in biology and medicine for which scientists have been awarded prestigious prizes including the Nobel Prize, Lasker Award and Breakthrough Prizes in life sciences. These have been the fruits of years of basic research. From time to time, publications have appeared listing "unsolved" problems in biology. In this article, I ask the question whether it is possible to have such a list, if not a unique one, at least one that is analogous to the Millennium Prize in mathematics. My approach to finding an answer to this question was to gather views of leading biologists. I have also included my own views. Analysis of all the responses received over several years has convinced me that it is difficult, but not impossible, to have such a prize. Biology is complex and very interdisciplinary these days at times involving large numbers of teams, unlike mathematics, where Andrew Wiles spent seven years in complete isolation and secrecy solving Fermat's last theorem. Such an approach is simply not possible in biology. Still I would like to suggest that a similar prize can be established by a panel of distinguished scientists. It would be awarded to those who solved one of the listed problems in biology that warrant a verifiable solution. Despite many different opinions, I found that there is some commonality in the responses I received - I go on to discuss what these are and how they may impact future thinking. PMID:25687284

  6. Taxation of Fringe Benefits: Alternative Approaches to Current Problems.

    ERIC Educational Resources Information Center

    Cohen, Anita E.

    1979-01-01

    The current IRS tax treatment of fringe benefits is seen as inadequate, and the judicial precept confusing, because groups of employee benefits are inappropriately excluded from taxation as perquisites. A tax equalization approach is proposed. Available from Suffolk University Law Review Office, 41 Temple St., Boston, MA 02114. (MSE)

  7. Reconsidering sore throats. Part I: Problems with current clinical practice.

    PubMed Central

    McIsaac, W. J.; Goel, V.; Slaughter, P. M.; Parsons, G. W.; Woolnough, K. V.; Weir, P. T.; Ennet, J. R.

    1997-01-01

    OBJECTIVE: To provide evidence-based answers to clinical questions posed by family physicians about Group A streptococcus pharyngitis and to further understanding of why management is controversial. QUALITY OF EVIDENCE: Evidence from randomized trials was not found for most questions. The most critical information came from high-quality community prevalence studies and criterion standard studies of physician clinical judgement. MAIN FINDINGS: Expert recommendations for physician management are not likely to help prevent rheumatic fever, as most people with sore throats do not seek medical care. Current clinical practices result in overuse of antibiotics because accuracy of clinical judgment is limited. CONCLUSIONS: Costs associated with visits for upper respiratory infections as well as increasing antibiotic resistance necessitate reconsidering the current clinical approach. An alternative management strategy is presented in part 2. PMID:9116520

  8. Transient three-dimensional contact problems: mortar method. Mixed methods and conserving integration

    NASA Astrophysics Data System (ADS)

    Hesch, Christian; Betsch, Peter

    2011-10-01

    The present work deals with the development of an energy-momentum conserving method to unilateral contact constraints and is a direct continuation of a previous work (Hesch and Betsch in Comput Mech 2011, doi: 10.1007/s00466-011-0597-2) dealing with the NTS method. In this work, we introduce the mortar method and a newly developed segmentation process for the consistent integration of the contact interface. For the application of the energy-momentum approach to mortar constraints, we extend an approach based on a mixed formulation to the segment definition of the mortar constraints. The enhanced numerical stability of the newly proposed discretization method will be shown in several examples.

  9. Captive breeding of pangolins: current status, problems and future prospects.

    PubMed

    Hua, Liushuai; Gong, Shiping; Wang, Fumin; Li, Weiye; Ge, Yan; Li, Xiaonan; Hou, Fanghui

    2015-01-01

    Pangolins are unique placental mammals with eight species existing in the world, which have adapted to a highly specialized diet of ants and termites, and are of significance in the control of forest termite disaster. Besides their ecological value, pangolins are extremely important economic animals with the value as medicine and food. At present, illegal hunting and habitat destruction have drastically decreased the wild population of pangolins, pushing them to the edge of extinction. Captive breeding is an important way to protect these species, but because of pangolin's specialized behaviors and high dependence on natural ecosystem, there still exist many technical barriers to successful captive breeding programs. In this paper, based on the literatures and our practical experience, we reviewed the status and existing problems in captive breeding of pangolins, including four aspects, the naturalistic habitat, dietary husbandry, reproduction and disease control. Some recommendations are presented for effective captive breeding and protection of pangolins. PMID:26155072

  10. Captive breeding of pangolins: current status, problems and future prospects.

    PubMed

    Hua, Liushuai; Gong, Shiping; Wang, Fumin; Li, Weiye; Ge, Yan; Li, Xiaonan; Hou, Fanghui

    2015-01-01

    Pangolins are unique placental mammals with eight species existing in the world, which have adapted to a highly specialized diet of ants and termites, and are of significance in the control of forest termite disaster. Besides their ecological value, pangolins are extremely important economic animals with the value as medicine and food. At present, illegal hunting and habitat destruction have drastically decreased the wild population of pangolins, pushing them to the edge of extinction. Captive breeding is an important way to protect these species, but because of pangolin's specialized behaviors and high dependence on natural ecosystem, there still exist many technical barriers to successful captive breeding programs. In this paper, based on the literatures and our practical experience, we reviewed the status and existing problems in captive breeding of pangolins, including four aspects, the naturalistic habitat, dietary husbandry, reproduction and disease control. Some recommendations are presented for effective captive breeding and protection of pangolins.

  11. Captive breeding of pangolins: current status, problems and future prospects

    PubMed Central

    Hua, Liushuai; Gong, Shiping; Wang, Fumin; Li, Weiye; Ge, Yan; Li, Xiaonan; Hou, Fanghui

    2015-01-01

    Abstract Pangolins are unique placental mammals with eight species existing in the world, which have adapted to a highly specialized diet of ants and termites, and are of significance in the control of forest termite disaster. Besides their ecological value, pangolins are extremely important economic animals with the value as medicine and food. At present, illegal hunting and habitat destruction have drastically decreased the wild population of pangolins, pushing them to the edge of extinction. Captive breeding is an important way to protect these species, but because of pangolin’s specialized behaviors and high dependence on natural ecosystem, there still exist many technical barriers to successful captive breeding programs. In this paper, based on the literatures and our practical experience, we reviewed the status and existing problems in captive breeding of pangolins, including four aspects, the naturalistic habitat, dietary husbandry, reproduction and disease control. Some recommendations are presented for effective captive breeding and protection of pangolins. PMID:26155072

  12. The clinical chemistry laboratory: current status, problems and diagnostic prospects.

    PubMed

    Schleicher, Erwin

    2006-01-01

    Although increased automation, advanced analytical techniques and sophisticated information technology have greatly improved the performance and quality in medical laboratory testing, several studies show that significant amounts of errors occur. Detailed analysis revealed that most of the errors occur in the preanalytical phase, while fewer errors occur in the intra- and post-analytical phase. The majority of errors are caused by wrong sampling or occur during transport to the laboratory. This review focuses on the analytical procedures in a large central laboratory. Possible problems are described by following samples from the patient to the laboratory and back. Finally, the advantages and disadvantages of point-of-care testing versus central laboratory are compared.

  13. Future of primary healthcare education: current problems and potential solutions.

    PubMed

    Lord, J

    2003-10-01

    This review examines the origins of primary care and the pressures currently faced in terms of patient expectation, regulation, accountability, and work force shortages. It recognises the appropriateness of adding to the burden in primary care further by the shift both of more services and more medical education from secondary care. Some conclusions are drawn concerning potential solutions including skill mix changes, centralisation of services, a change in attitudes to professional mistakes, increased protected development time, evidence based education, and academic, leadership, and feedback skills for general practitioners. Six recommendations are offered as a prescription for organisational and educational change. PMID:14612596

  14. Three-dimensional simulation of electron beam induced current collected by a nano-contact: Diffusion and collection analysis

    NASA Astrophysics Data System (ADS)

    Doan, Q. T.; El Hdiy, A.; Troyon, M.

    2011-12-01

    Three-dimensional simulation is used to study the electron beam induced current collected by a nano-contact forming a nano-junction. For the calculation the surface recombination velocity is supposed to be either infinite or zero. The influence of the bulk diffusion length, energy of the incident electron beam, shape and size of the depletion zone beneath the nano-contact on the induced current collected by the nano-junction is studied. From the fit of the simulated data, the minority carrier effective diffusion length is extracted, and its variation with the electron beam energy is compared with experimental measurements obtained with the nano-EBIC (electron beam induced current) technique that we have developed by combining scanning probe microscopy and scanning electron microscopy. The effective diffusion length is an increasing function with electron beam energy up to a certain value beyond which it decreases. The simulation shows that the same behavior also occurs in the case of the conventional detection by a semi-infinite Schottky contact perpendicular to the electron beam. This is the first time, to our knowledge, that this behavior is pointed out.

  15. [Acral lentiginous melanoma: the current state of the problem].

    PubMed

    Myasnyankin, M Yu; Gafton, G I; Anisimov, V V; Matsko, D E; Imyanitov, E N; Semiletova, Yu V

    2015-01-01

    This review is aimed at the analysis the current state of acral lentiginous melanoma. This tumor has rather aggressive course and is the main cause of death in skin cancer patients. In Russia the incidence of melanoma during the period 2000-2010 increased from 3.18 to 3.95 cases per 100000 of population. The average annual growth rate was 1.99% and the total growth rate was 21.81%. Although skin melanoma is a visual tumor, more than one third of patients visit oncologists at advanced stages of the disease. Primary melanoma with localizations on the skin of fingers, interdigital spaces, soles, palms and nail plates is especially difficult for early diagnostics.

  16. Shift work and health: current problems and preventive actions.

    PubMed

    Costa, Giovanni

    2010-12-01

    The paper gives an overview of the problems to be tackled nowadays by occupational health with regards to shift work as well as the main guidelines at organizational and medical levels on how to protect workers' health and well-being. Working time organization is becoming a key factor on account of new technologies, market globalization, economic competition, and extension of social services to general populations, all of which involve more and more people in continuous assistance and control of work processes over the 24 hours in a day. The large increase of epidemiological and clinical studies on this issue document the severity of this risk factor on human health and well being, at both social and psychophysical levels, starting from a disruption of biological circadian rhythms and sleep/wake cycle and ending in several psychosomatic troubles and disorders, likely also including cancer, and extending to impairment of performance efficiency as well as family and social life. Appropriate interventions on the organization of shift schedules according to ergonomic criteria and careful health surveillance and social support for shift workers are important preventive and corrective measures that allow people to keep working without significant health impairment. PMID:22953171

  17. Current status and problems of lung transplantation in Japan

    PubMed Central

    2016-01-01

    Lung transplantation has been performed worldwide and recognized as an effective treatment for patients with various end-stage lung diseases. Shortage of lung donors is one of the main obstacles in most of the countries, especially in Japan. Every effort has been made to promote organ donation during the past 20 years. In 2010, Japanese transplant low was revised so that the family of the brain dead donors can make a decision for organ donation. Since then, the number of cadaveric lung donor has increased by 5-fold. However, the average waiting time is still more than 800 days resulting in considerable number of deaths on the waiting list. Lung transplantation in the use of donation after cardiac death (DCD) has now been increasingly performed in Europe, Australia and North America with promising results. However, controlled death is not permitted in Japan making it difficult to accept this strategy. Use of marginal donors is one of the strategies for organ shortage. In Japan, the rate of lung usage is now well over 60% because of careful donor management by medical consultants and aggressive use of marginal donors. Living-donor lobar lung transplantation (LDLLT) has been developed to offset the mismatch between supply and demand for those patients awaiting cadaveric lung transplantation (CLT) and it is often the most realistic option for very ill patients. Between 1998 and 2015, lung transplantation has been performed in 464 patients (55 children, 419 adults) at 9 lung transplant centers in Japan. CLT was performed in 283 patients (61%) and LDLLT was performed in 181 patients (39%). The 5-year survival was 72.3% and 71.6%, respectively. Of note, only seven children received CLT. In conclusion, lung transplantation in Japan has grown significantly with excellent results but the shortage of cadaveric lung donor remains to be an important unsolved problem. LDLLT is often the only realistic option for very ill patients especially for children. PMID:27651939

  18. Current status and problems of lung transplantation in Japan

    PubMed Central

    2016-01-01

    Lung transplantation has been performed worldwide and recognized as an effective treatment for patients with various end-stage lung diseases. Shortage of lung donors is one of the main obstacles in most of the countries, especially in Japan. Every effort has been made to promote organ donation during the past 20 years. In 2010, Japanese transplant low was revised so that the family of the brain dead donors can make a decision for organ donation. Since then, the number of cadaveric lung donor has increased by 5-fold. However, the average waiting time is still more than 800 days resulting in considerable number of deaths on the waiting list. Lung transplantation in the use of donation after cardiac death (DCD) has now been increasingly performed in Europe, Australia and North America with promising results. However, controlled death is not permitted in Japan making it difficult to accept this strategy. Use of marginal donors is one of the strategies for organ shortage. In Japan, the rate of lung usage is now well over 60% because of careful donor management by medical consultants and aggressive use of marginal donors. Living-donor lobar lung transplantation (LDLLT) has been developed to offset the mismatch between supply and demand for those patients awaiting cadaveric lung transplantation (CLT) and it is often the most realistic option for very ill patients. Between 1998 and 2015, lung transplantation has been performed in 464 patients (55 children, 419 adults) at 9 lung transplant centers in Japan. CLT was performed in 283 patients (61%) and LDLLT was performed in 181 patients (39%). The 5-year survival was 72.3% and 71.6%, respectively. Of note, only seven children received CLT. In conclusion, lung transplantation in Japan has grown significantly with excellent results but the shortage of cadaveric lung donor remains to be an important unsolved problem. LDLLT is often the only realistic option for very ill patients especially for children.

  19. Current status and problems of lung transplantation in Japan.

    PubMed

    Date, Hiroshi

    2016-08-01

    Lung transplantation has been performed worldwide and recognized as an effective treatment for patients with various end-stage lung diseases. Shortage of lung donors is one of the main obstacles in most of the countries, especially in Japan. Every effort has been made to promote organ donation during the past 20 years. In 2010, Japanese transplant low was revised so that the family of the brain dead donors can make a decision for organ donation. Since then, the number of cadaveric lung donor has increased by 5-fold. However, the average waiting time is still more than 800 days resulting in considerable number of deaths on the waiting list. Lung transplantation in the use of donation after cardiac death (DCD) has now been increasingly performed in Europe, Australia and North America with promising results. However, controlled death is not permitted in Japan making it difficult to accept this strategy. Use of marginal donors is one of the strategies for organ shortage. In Japan, the rate of lung usage is now well over 60% because of careful donor management by medical consultants and aggressive use of marginal donors. Living-donor lobar lung transplantation (LDLLT) has been developed to offset the mismatch between supply and demand for those patients awaiting cadaveric lung transplantation (CLT) and it is often the most realistic option for very ill patients. Between 1998 and 2015, lung transplantation has been performed in 464 patients (55 children, 419 adults) at 9 lung transplant centers in Japan. CLT was performed in 283 patients (61%) and LDLLT was performed in 181 patients (39%). The 5-year survival was 72.3% and 71.6%, respectively. Of note, only seven children received CLT. In conclusion, lung transplantation in Japan has grown significantly with excellent results but the shortage of cadaveric lung donor remains to be an important unsolved problem. LDLLT is often the only realistic option for very ill patients especially for children. PMID:27651939

  20. Health care economics in Serbia: current problems and changes.

    PubMed

    Stosić, Sanja; Karanović, Nevena

    2014-11-01

    One of the fundamental rights of every human being is to enjoy "the highest attainable standard of health". Achieving better health requires no only adequate medical knowledge and technologies, laws and social measures in the field of health care, but also sufficient funding for fulfilling people's right to health. However, economic crisis has left every community with limited possibility of investing in health care and forced them to use the available resources more efficiently. This is the reason why health financing policy represents an important and integral part of the health system concerned with how financial resources are generated, allocated and used. Development of new drugs and medical technologies, population aging, increased incidence of chronic diseases as well as the peoples' rising demands from health care providers lead to a constant increase of health system costs worldwide. In these circumstances, countries in transition, like Serbia, face difficult challenges in financing their health systems. Current economic crisis and budget constraints do not allow the Government to simply allocate more public revenues for health and solve the people's expectations by increasing the spending. Instead, Serbia is forced to start reforms to provide a more efficient health system. The reform processes are positioned within the wider context of European integration and public administration reforms. This paper provides a short description of the health care system in Serbia focusing on the healthcare economics and reforms and their influence on financial sustainability.

  1. Technologies for Continuous Glucose Monitoring: Current Problems and Future Promises

    PubMed Central

    Vaddiraju, Santhisagar; Burgess, Diane J; Tomazos, Ioannis; Jain, Faquir C; Papadimitrakopoulos, Fotios

    2010-01-01

    Devices for continuous glucose monitoring (CGM) are currently a major focus of research in the area of diabetes management. It is envisioned that such devices will have the ability to alert a diabetes patient (or the parent or medical care giver of a diabetes patient) of impending hypoglycemic/hyperglycemic events and thereby enable the patient to avoid extreme hypoglycemic/hyperglycemic excursions as well as minimize deviations outside the normal glucose range, thus preventing both life-threatening events and the debilitating complications associated with diabetes. It is anticipated that CGM devices will utilize constant feedback of analytical information from a glucose sensor to activate an insulin delivery pump, thereby ultimately realizing the concept of an artificial pancreas. Depending on whether the CGM device penetrates/breaks the skin and/or the sample is measured extracorporeally, these devices can be categorized as totally invasive, minimally invasive, and noninvasive. In addition, CGM devices are further classified according to the transduction mechanisms used for glucose sensing (i.e., electrochemical, optical, and piezoelectric). However, at present, most of these technologies are plagued by a variety of issues that affect their accuracy and long-term performance. This article presents a critical comparison of existing CGM technologies, highlighting critical issues of device accuracy, foreign body response, calibration, and miniaturization. An outlook on future developments with an emphasis on long-term reliability and performance is also presented. PMID:21129353

  2. Current Status of the Problem of Cosmological Variability of Fundamental Physical Constants

    NASA Astrophysics Data System (ADS)

    Varshslovich, D.A.; Ivanchik, A.V.; Orlov, A.V.; Potekhin, A.Y.; Petitjean, P.

    We review the current status of the problem of cosmological variability of fundamental physical constants, provided by modern laboratory experiments, Oklo phenomena analysis, and especially astronomical observations.

  3. Ti/Pd/Ag Contacts to n-Type GaAs for High Current Density Devices

    NASA Astrophysics Data System (ADS)

    Huo, Pengyun; Rey-Stolle, Ignacio

    2016-06-01

    The metallization stack Ti/Pd/Ag on n-type Si has been readily used in solar cells due to its low metal/semiconductor specific contact resistance, very high sheet conductance, bondability, long-term durability, and cost-effectiveness. In this study, the use of Ti/Pd/Ag metallization on n-type GaAs is examined, targeting electronic devices that need to handle high current densities and with grid-like contacts with limited surface coverage (i.e., solar cells, lasers, or light emitting diodes). Ti/Pd/Ag (50 nm/50 nm/1000 nm) metal layers were deposited on n-type GaAs by electron beam evaporation and the contact quality was assessed for different doping levels (from 1.3 × 1018 cm-3 to 1.6 × 1019 cm-3) and annealing temperatures (from 300°C to 750°C). The metal/semiconductor specific contact resistance, metal resistivity, and the morphology of the contacts were studied. The results show that samples doped in the range of 1018 cm-3 had Schottky-like I- V characteristics and only samples doped 1.6 × 1019 cm-3 exhibited ohmic behavior even before annealing. For the ohmic contacts, increasing annealing temperature causes a decrease in the specific contact resistance ( ρ c,Ti/Pd/Ag ~ 5 × 10-4 Ω cm2). In regard to the metal resistivity, Ti/Pd/Ag metallization presents a very good metal conductivity for samples treated below 500°C ( ρ M,Ti/Pd/Ag ~ 2.3 × 10-6 Ω cm); however, for samples treated at 750°C, metal resistivity is strongly degraded due to morphological degradation and contamination in the silver overlayer. As compared to the classic AuGe/Ni/Au metal system, the Ti/Pd/Ag system shows higher metal/semiconductor specific contact resistance and one order of magnitude lower metal resistivity.

  4. Isotropic contact forces in arbitrary representation: Heterogeneous few-body problems and low dimensions

    SciTech Connect

    Pricoupenko, Ludovic

    2011-06-15

    The Bethe-Peierls asymptotic approach which models pairwise short-range forces by contact conditions is introduced in arbitrary representation for spatial dimensions less than or equal to 3. The formalism is applied in various situations and emphasis is put on the momentum representation. In the presence of a transverse harmonic confinement, dimensional reduction toward two-dimensional (2D) or one-dimensional (1D) physics is derived within this formalism. The energy theorem relating the mean energy of an interacting system to the asymptotic behavior of the one-particle density matrix illustrates the method in its second quantized form. Integral equations that encapsulate the Bethe-Peierls contact condition for few-body systems are derived. In three dimensions, for three-body systems supporting Efimov states, a nodal condition is introduced in order to obtain universal results from the Skorniakov-Ter-Martirosian equation and the Thomas collapse is avoided. Four-body bound state eigenequations are derived and the 2D {sup '}3+1{sup '} bosonic ground state is computed as a function of the mass ratio.

  5. Dynamics of a belt-drive system using a linear complementarity problem for the belt pulley contact description

    NASA Astrophysics Data System (ADS)

    Čepon, Gregor; Boltežar, Miha

    2009-01-01

    The aim of this study was to develop an efficient and realistic numerical model in order to predict the dynamic response of belt drives. The belt was modeled as a planar beam element based on an absolute nodal coordinate formulation. A viscoelastic material was adopted for the belt and the corresponding damping and stiffness matrices were determined. The belt-pulley contact was formulated as a linear complementarity problem together with a penalty method. This made it possible for us to accurately predict the contact forces, including the stick and slip zones between the belt and the pulley. The belt-drive model was verified by comparing it with the available analytical solutions. A good agreement was found. Finally, the applicability of the method was demonstrated by considering non-steady belt-drive operating conditions.

  6. Non-contact current and voltage sensor having detachable housing incorporating multiple ferrite cylinder portions

    DOEpatents

    Carpenter, Gary D.; El-Essawy, Wael; Ferreira, Alexandre Peixoto; Keller, Thomas Walter; Rubio, Juan C.; Schappert, Michael A.

    2016-04-26

    A detachable current and voltage sensor provides an isolated and convenient device to measure current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing formed from two portions that mechanically close around the wire and that contain the current and voltage sensors. The current sensor is a ferrite cylinder formed from at least three portions that form the cylinder when the sensor is closed around the wire with a hall effect sensor disposed in a gap between two of the ferrite portions along the circumference to measure current. A capacitive plate or wire is disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.

  7. Geology and religion - historical perspective and current problems

    NASA Astrophysics Data System (ADS)

    Kölbl-Ebert, Martina

    2010-05-01

    Today, when referring to the relationship between geology and religion, people usually at once think of Christian (and other) fundamentalists and their chronic palaeontological illiteracy leading to Creationism, to Intelligent Design, and a distrust of science in general among them most prominently geology, palaeontology and evolutionary biology. Thus the relationship of geology and religion is usually considered to be under strain. In former times things used to be quite different, and for most of human history the observation of geological phenomena and the acquisition of geological expertise was intimately connected with religious ideas. The Judeo-Christian sense of a finite Earth history prepared the ground for accepting the Earth's different strata as testimony to the development of our globe through time. It was this religious, theological framework, from which the early geology started to evolve. However, with increasing observations there was a growing mismatch between what was expected according to ancient, scriptural authorities and the actual data. The release of geology from religious connotations or associations was a development closely connected with the Enlightenment, when geology and religion started to drift apart not with a violent rupture but in a subtle and sometimes circuitous manner. However, outside the group of people with geological expertise, not all was smooth and peaceful, and some conservative clergymen as well as laypersons were rather shocked by the new ideas that came with geology: the immensity of the timescale, a dynamic Earth, not just a ruin shaped by the Deluge, and a dynamic biology too with the Darwinian theory of evolution, which was founded in part on palaeontological evidence and the assumption of a long geological time scale. Nevertheless and interestingly the Creationism we face today is a rather recent phenomenon influenced by a number of motives, most of them philosophical and theological in nature. And so, the current

  8. Non-contact current and voltage sensing method using a clamshell housing and a ferrite cylinder

    DOEpatents

    Carpenter, Gary D.; El-Essawy, Wael; Ferreira, Alexandre Peixoto; Keller, Thomas Walter; Rubio, Juan C.; Schappert, Michael

    2016-04-26

    A method of measurement using a detachable current and voltage sensor provides an isolated and convenient technique for to measuring current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing that contains the current and voltage sensors, which may be a ferrite cylinder with a hall effect sensor disposed in a gap along the circumference to measure current, or alternative a winding provided through the cylinder along its axis and a capacitive plate or wire disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.

  9. Promoting Health by Addressing Basic Needs: Effect of Problem Resolution on Contacting Health Referrals

    ERIC Educational Resources Information Center

    Thompson, Tess; Kreuter, Matthew W.; Boyum, Sonia

    2016-01-01

    Members of vulnerable populations have heightened needs for health services. One advantage of integrating health risk assessment and referrals into social service assistance systems such as 2-1-1 is that such systems help callers resolve problems in other areas (e.g., housing). Callers to 2-1-1 in Missouri (N = 1,090) with at least one behavioral…

  10. One-Step, Non-Contact Pattern Transfer by Direct-Current Plasma Immersion Ion Implantation

    NASA Astrophysics Data System (ADS)

    Kwok, Dixon T. K.; Chu, Paul K.

    2009-10-01

    A one-step non-contact pattern transferring method is demonstrated. Clear non-identical images with well-defined boundaries are simultaneously transferred to a substrate by -15 kV plasma immersion ion implantation through a patterned metal mask. The metal mask is 6 cm away from the substrate and no lens system is necessary for the pattern transfer. To avoid diversification of compensating ions, the electric field must be smoothed out by the fine mesh overlapping on top of the metal mask. Complex patterns with micrometer size line-widths can be transferred onto a silicon wafer by placing the metal masks 4 mm away from the wafer. Scanning electron microscopy (SEM) discloses that by negatively biasing the metal mask, ions coming from a hole with a diameter of 200 micrometers in the mask can be confined to a smaller region of 100 micrometers. The ion focusing effect is confirmed by two-dimensional multiple grid particle-in-cell (PIC) simulation.

  11. Patch testing with markers of fragrance contact allergy. Do clinical tests correspond to patients' self-reported problems?

    PubMed

    Johansen, J D; Andersen, T F; Veien, N; Avnstorp, C; Andersen, K E; Menné, T

    1997-03-01

    The aim of the present study was to investigate the relationship between patients' own recognition of skin problems using consumer products and the results of patch testing with markers of fragrance sensitization. Eight hundred and eighty-four consecutive eczema patients, 18-69 years of age, filled in a questionnaire prior to patch testing with the European standard series. The questionnaire contained questions about skin symptoms from the use of scented and unscented products as well as skin reactions from contact with spices, flowers and citrus fruits that could indicate fragrance sensitivity. A highly significant association was found between reporting a history of visible skin symptoms from using scented products and a positive patch test to the fragrance mix, whereas no such relationship could be established to the Peru balsam in univariate or multivariate analysis. Our results suggest that the role of Peru balsam in detecting relevant fragrance contact allergy is limited, while most fragrance mix-positive patients are aware that the use of scented products may cause skin problems.

  12. Consultation System with Contact Person through On-demand Calling of a Proper Expert for a Problem

    NASA Astrophysics Data System (ADS)

    Terahama, Yukinori; Kojima, Hiroyuki; Mizuno, Hirotaka; Kinukawa, Hiroshi

    The financial service counter is consisted of several advisory services, and service improvement is needed to offer effectively proper responses for various kinds of customer request. But it is not practical to put various expert staffs at each financial branch office, because of much cost and task performance falling. This paper proposes the window consultation system with contact persons at the financial branch office through on-demand calling of a proper expert for a problem. This proposed system has mainly two functions, remote experts selection and tele-consultation function, to offer replies or expert advises to the problem, using multimedia network technology. Customers can consult effectively with a proper expert staff about their requests through the proposed system, because it can connect the expert by the clerk of the window counter who comprehends beforehand the customer's requests. This system with contact persons can offer high quality services and avoid mistakes, which a customer makes in operating the consultation systems terminal alone by oneself. And this system is composed of three-layered structures, application component layer, middleware component layer and fundamental component layer. This structure is able to construct much easily various services at various scale financial branch office.

  13. Phylogeography Study of Ammodytes personatus in Northwestern Pacific: Pleistocene Isolation, Temperature and Current Conducted Secondary Contact

    PubMed Central

    Han, Zhiqiang; Yanagimoto, Takashi; Zhang, Yaping; Gao, Tianxiang

    2012-01-01

    To assess the role of historical process and contemporary factors in shaping population structures in Northwestern Pacific, mitochondrial control region sequences were analyzed to characterize the phylogeography and population structure of the Japanese sand lance Ammodytes personatus. A total of 429 individuals sampled from 17 populations through the species' range are sequenced. Two distinct lineages are detected, which might have been divergent in the Sea of Japan and Pacific costal waters of Japanese Island, during the low sea level. Significant genetic structure is revealed between the Kuroshio and Oyashio Currents. However, significant genetic structure is also detected in the Sea of Japan, contracting expected homogenization hypothesis in Tsushima Current. The haplotype frequency of lineages in both sides of Japanese Island and significant genetic structure between north and south groups revealed that the distribution of lineage B and north group were highly limited by the annual sea temperature. The lack of lineage B in Qingdao population with low sea temperature reflects the sea temperature barrier. Lack of genetic structure in the south group and north group populations indicated that ocean currents within groups facilitated the dispersal of A. personatus. PMID:22685527

  14. Phylogeography study of Ammodytes personatus in Northwestern Pacific: Pleistocene isolation, temperature and current conducted secondary contact.

    PubMed

    Han, Zhiqiang; Yanagimoto, Takashi; Zhang, Yaping; Gao, Tianxiang

    2012-01-01

    To assess the role of historical process and contemporary factors in shaping population structures in Northwestern Pacific, mitochondrial control region sequences were analyzed to characterize the phylogeography and population structure of the Japanese sand lance Ammodytes personatus. A total of 429 individuals sampled from 17 populations through the species' range are sequenced. Two distinct lineages are detected, which might have been divergent in the Sea of Japan and Pacific costal waters of Japanese Island, during the low sea level. Significant genetic structure is revealed between the Kuroshio and Oyashio Currents. However, significant genetic structure is also detected in the Sea of Japan, contracting expected homogenization hypothesis in Tsushima Current. The haplotype frequency of lineages in both sides of Japanese Island and significant genetic structure between north and south groups revealed that the distribution of lineage B and north group were highly limited by the annual sea temperature. The lack of lineage B in Qingdao population with low sea temperature reflects the sea temperature barrier. Lack of genetic structure in the south group and north group populations indicated that ocean currents within groups facilitated the dispersal of A. personatus.

  15. Multiplicity of inhabited worlds and the problem of setting up contacts among them

    NASA Technical Reports Server (NTRS)

    Shklovskiy, I. S.

    1974-01-01

    The numerous planetary systems in our galaxy appear to a high degree of probability to contain some planets with a biosphere similar to earth' environment. The possibility of communicating with those extraterrestrial alien planetary civilizations centers on the high level of technological development that is required to overcome the problem of distance. It is conceivable that advanced civilizations can produce energy at a level of 10 to the 43rd power erg/year and that an artificial biosphere can be developed within the limits of 10 to the 22nd power to 10 to the 23rd power cm.

  16. Modeling of the anode surface deformation in high-current vacuum arcs with AMF contacts

    NASA Astrophysics Data System (ADS)

    Huang, Xiaolong; Wang, Lijun; Deng, Jie; Jia, Shenli; Qin, Kang; Shi, Zongqian

    2016-02-01

    A high-current vacuum arc subjected to an axial magnetic field is maintained in a diffuse status. With an increase in arc current, the energy carried by the arc column to the anode becomes larger and finally leads to the anode temperature exceeding the melting point of the anode material. When the anode melting pool is formed, and the rotational plasma of the arc column delivers its momentum to the melting pool, the anode melting pool starts to rotate and also flow outwards along the radial direction, which has been photographed by some researchers using high-speed cameras. In this paper, the anode temperature and melting status is calculated using the melting and solidification model. The swirl flow of the anode melting pool and deformation of the anode is calculated using the magneto-hydrodynamic (MHD) model with the volume of fraction (VOF) method. All the models are transient 2D axial-rotational symmetric models. The influence of the impaction force of the arc plasma, electromagnetic force, viscosity force, and surface tension of the liquid metal are all considered in the model. The heat flux density injected into the anode and the arc pressure are obtained from the 3D numerical simulation of the high-current vacuum arc using the MHD model, which gives more realistic parameters for the anode simulation. Simulation results show that the depth of the anode melting pool increases with an increase in the arc current. Some droplets sputter out from the anode surface, which is caused by the inertial centrifugal force of the rotational melting pool and strong plasma pressure. Compared with the previous anode melting model without consideration of anode deformation, when the deformation and swirl flow of the anode melting pool are considered, the anode temperature is relatively lower, and just a little more than the melting point of Cu. This is because of liquid droplets sputtering out of the anode surface taking much of the energy away from the anode surface. The

  17. Non-contact current-phase measurements of topological weak links with scanning SQUID

    NASA Astrophysics Data System (ADS)

    Watson, C. A.; Sochnikov, I.; Kirtley, J. R.; Moler, K. A.; Deng, M.; Chang, W.; Krogstrup, P.; Jespersen, T. S.; Nygard, J.; Marcus, C. M.; Maier, L.; Gould, C.; Tkachov, G.; Hankiewicz, E. M.; Brüne, C.; Buhmann, H.; Molenkamp, L. W.

    2015-03-01

    Topological superconductivity has recently generated substantial interest as a pathway to Majorana physics in the solid state. Experimental efforts have focused on the superconducting proximity effect in topologically non-trivial junctions, but proof of the topological nature of the induced superconductivity remains elusive. We employ scanning superconducting quantum interference device (SQUID) susceptometry to study conventional superconducting Nb rings interrupted by weak links of 3D topological insulator HgTe and Al rings with InAs nanowire junctions. Varying the flux through each ring, we directly measure the current-phase relation (CPR) of the junction. Forward skewness in the CPR of 3D-HgTe which persists even in junctions long compared to the mean free path suggests that helicity may play a role in the high transmittance of Andreev Bound States that carry the Josephson current. Progress in InAs nanowire junction CPR measurements is also discussed. These measurements showcase the CPR as a fundamental characteristic of superconducting weak links and establish scanning SQUID microscopy as a powerful probe for performing such measurements.

  18. Non-contact ACL injuries in female athletes: an International Olympic Committee current concepts statement

    PubMed Central

    Renstrom, P; Ljungqvist, A; Arendt, E; Beynnon, B; Fukubayashi, T; Garrett, W; Georgoulis, T; Hewett, T E; Johnson, R; Krosshaug, T; Mandelbaum, B; Micheli, L; Myklebust, G; Roos, E; Roos, H; Schamasch, P; Shultz, S; Werner, S; Wojtys, E; Engebretsen, L

    2014-01-01

    The incidence of anterior cruciate ligament (ACL) injury remains high in young athletes. Because female athletes have a much higher incidence of ACL injuries in sports such as basketball and team handball than male athletes, the IOC Medical Commission invited a multidisciplinary group of ACL expert clinicians and scientists to (1) review current evidence including data from the new Scandinavian ACL registries; (2) critically evaluate high-quality studies of injury mechanics; (3) consider the key elements of successful prevention programmes; (4) summarise clinical management including surgery and conservative management; and (5) identify areas for further research. Risk factors for female athletes suffering ACL injury include: (1) being in the preovulatory phase of the menstrual cycle compared with the postovulatory phase; (2) having decreased intercondylar notch width on plain radiography; and (3) developing increased knee abduction moment (a valgus intersegmental torque) during impact on landing. Well-designed injury prevention programmes reduce the risk of ACL for athletes, particularly women. These programmes attempt to alter dynamic loading of the tibiofemoral joint through neuromuscular and proprioceptive training. They emphasise proper landing and cutting techniques. This includes landing softly on the forefoot and rolling back to the rearfoot, engaging knee and hip flexion and, where possible, landing on two feet. Players are trained to avoid excessive dynamic valgus of the knee and to focus on the “knee over toe position” when cutting. PMID:18539658

  19. Non-contact ACL injuries in female athletes: an International Olympic Committee current concepts statement.

    PubMed

    Renstrom, P; Ljungqvist, A; Arendt, E; Beynnon, B; Fukubayashi, T; Garrett, W; Georgoulis, T; Hewett, T E; Johnson, R; Krosshaug, T; Mandelbaum, B; Micheli, L; Myklebust, G; Roos, E; Roos, H; Schamasch, P; Shultz, S; Werner, S; Wojtys, E; Engebretsen, L

    2008-06-01

    The incidence of anterior cruciate ligament (ACL) injury remains high in young athletes. Because female athletes have a much higher incidence of ACL injuries in sports such as basketball and team handball than male athletes, the IOC Medical Commission invited a multidisciplinary group of ACL expert clinicians and scientists to (1) review current evidence including data from the new Scandinavian ACL registries; (2) critically evaluate high-quality studies of injury mechanics; (3) consider the key elements of successful prevention programmes; (4) summarise clinical management including surgery and conservative management; and (5) identify areas for further research. Risk factors for female athletes suffering ACL injury include: (1) being in the preovulatory phase of the menstrual cycle compared with the postovulatory phase; (2) having decreased intercondylar notch width on plain radiography; and (3) developing increased knee abduction moment (a valgus intersegmental torque) during impact on landing. Well-designed injury prevention programmes reduce the risk of ACL for athletes, particularly women. These programmes attempt to alter dynamic loading of the tibiofemoral joint through neuromuscular and proprioceptive training. They emphasise proper landing and cutting techniques. This includes landing softly on the forefoot and rolling back to the rearfoot, engaging knee and hip flexion and, where possible, landing on two feet. Players are trained to avoid excessive dynamic valgus of the knee and to focus on the "knee over toe position" when cutting.

  20. [Current problems of metrological support for medical laboratory technology for microanalysis].

    PubMed

    Anufriev, Iu A; Pashkevich, E V; Kuznetsov, A D; Mochalov, V S; Galushkin, A N

    1986-01-01

    Consideration is given to current concepts and general problems of metrological support for clinical microanalytical laboratory instrumentation. The impact of varying environmental conditions is evaluated with due regard to transition to microdoses. PMID:3784863

  1. The Case of Web-Based Course on Taxation: Current Status, Problems and Future Improvement

    NASA Astrophysics Data System (ADS)

    Qin, Zhigang

    This paper mainly introduces the case of the web-based course on taxation developed by Xiamen University. We analyze the current status, problems and future improvement of the web-based course. The web-based course has the basic contents and modules, but it has several problems including unclear object, lacking interaction, lacking examination module, lacking study management module, and the learning materials and the navigation are too simple. According to its problems, we put forward the measures to improve it.

  2. Rotary electrical contact device and method for providing current to and/or from a rotating member

    DOEpatents

    Koplow, Jeffrey P

    2013-11-19

    Examples of rotary electrical connectors include a first pair and a second pair of opposing sheaves coupled together by intersecting first shaft connecting the first pair of opposing sheaves and a second shaft connecting the second pair of opposing sheaves, and at least partially electrically conductive belt disposed about respective perimeters of the first pair and second pair of opposing sheaves and adapted to remain in contact with at least a portion of the respective perimeters of the sheaves during motion of said sheaves. In example devices, one of the plurality of sheaves may remain stationary during operation of the device while the remaining sheaves rotate and/or orbit around a center axis of the stationary sheave, the device being configured to couple current between a stationary power source and a rotating member through the electrically conductive belt.

  3. Role of height and contact interface of CNT microstructures on Si for high current field emission cathodes

    NASA Astrophysics Data System (ADS)

    Navitski, A.; Serbun, P.; Müller, G.; Joshi, R. K.; Engstler, J.; Schneider, J. J.

    2012-07-01

    Regular arrays of vertically aligned microstructures consisting of entangled carbon nanotubes (CNTs) of different height and contact interface were grown on Si substrates with a bimetallic catalyst by water-assisted chemical vapor deposition. The arrays of high and wide CNT blocks (150-300 μm, 50-140 μm square) showed the ability to reach high stable field emission (FE) currents per block up to 300 μA due to the presence of multiple CNT emitters. However, significant outgrowth of the CNTs and limited mechanical stiffness of such blocks led to a limited FE homogeneity and alignment of the emitters. For the arrays of small rounded CNT bundles (˜5 μm, 20 μm diameter), well-aligned and highly efficient FE with maximum currents up to 40 μA per CNT bundle have been achieved. Unusual I-V curves with current saturation, strong activation effects and glowing spots just before destruction have been observed and are discussed by means of band structure considerations.

  4. Solution of 3D inverse scattering problems by combined inverse equivalent current and finite element methods

    SciTech Connect

    Kılıç, Emre Eibert, Thomas F.

    2015-05-01

    An approach combining boundary integral and finite element methods is introduced for the solution of three-dimensional inverse electromagnetic medium scattering problems. Based on the equivalence principle, unknown equivalent electric and magnetic surface current densities on a closed surface are utilized to decompose the inverse medium problem into two parts: a linear radiation problem and a nonlinear cavity problem. The first problem is formulated by a boundary integral equation, the computational burden of which is reduced by employing the multilevel fast multipole method (MLFMM). Reconstructed Cauchy data on the surface allows the utilization of the Lorentz reciprocity and the Poynting's theorems. Exploiting these theorems, the noise level and an initial guess are estimated for the cavity problem. Moreover, it is possible to determine whether the material is lossy or not. In the second problem, the estimated surface currents form inhomogeneous boundary conditions of the cavity problem. The cavity problem is formulated by the finite element technique and solved iteratively by the Gauss–Newton method to reconstruct the properties of the object. Regularization for both the first and the second problems is achieved by a Krylov subspace method. The proposed method is tested against both synthetic and experimental data and promising reconstruction results are obtained.

  5. The current status and future direction of self-help treatments for problem gamblers.

    PubMed

    Raylu, Namrata; Oei, Tian P S; Loo, Jasmine

    2008-12-01

    The self-help treatment (SHT) studies for other psychological problems significantly outweigh those for problem gambling. Currently, very little is published about the application and efficacy of various forms of SHTs for problem gambling. Thus, this paper reviews the self-help literature (using the PsycINFO database--all years up to April 2008) to stimulate further research in this area for problem gambling. The findings show that SHTs in problem gambling are still in their infancy. Although the problem gambling literature has mainly reported on two forms of SHTs with problem gamblers (i.e. use of self-help manuals and audiotapes), the review discuss utilizing a wide range of SHTs with problem gamblers. These include written materials (e.g. self-help books and treatment manuals), audiotapes, videotapes, computer-based SHTs implemented on palmtop computers, desktop computers, via telephone (Interactive Voice Response systems--IVR) or via the Internet and virtual reality applications. These SHTs would suit those problem gamblers who are not accessing professional treatment due to shame, guilt, fear of stigma, privacy concerns or financial difficulties, as well as those living in rural areas or with less severe gambling problems. The review also suggest future protocols for conducting further research in this area with problem gamblers, highlighting a need for a cohesive theory to guide research.

  6. The effects of an uncapped nanocrystal on a simulated induced current collected by a nano-contact

    SciTech Connect

    Doan, Quang-Tri; El Hdiy, Abdelillah

    2015-03-21

    The effects of the charge capture process by an isolated and uncapped nanocrystal on the electron beam induced current are studied by the use of the Monte Carlo simulation. In the calculation, the current is created by an electron beam irradiation and is collected by a hemispherical nano-contact. The nanocrystal is considered as a recombination center, and the surface recombination velocity at the free surface is assumed to be equal to zero. The diffusion length is taken out from the fitting of simulated collection efficiency profiles, and studied as a function of the electron beam energy. The diffusion length rapidly decreases at very low energy (≤∼5 keV), increases to reach a maximum at middle energies (∼13 keV), and then decreases to reach saturation for high energy (≥∼25 keV). The effect of the isolated nanocrystal at the surface is highlighted at high energy, when the diffusion length becomes energy independent. This situation leads to determination of effective surface recombination velocities the values of which underline the trapping process in the nanocrystal.

  7. A non-Hertzian method for solving wheel-rail normal contact problem taking into account the effect of yaw

    NASA Astrophysics Data System (ADS)

    Liu, Binbin; Bruni, Stefano; Vollebregt, Edwin

    2016-09-01

    A novel approach is proposed in this paper to deal with non-Hertzian normal contact in wheel-rail interface, extending the widely used Kik-Piotrowski method. The new approach is able to consider the effect of the yaw angle of the wheelset against the rail on the shape of the contact patch and on pressure distribution. Furthermore, the method considers the variation of profile curvature across the contact patch, enhancing the correspondence to CONTACT for highly non-Hertzian contact conditions. The simulation results show that the proposed method can provide more accurate estimation than the original algorithm compared to Kalker's CONTACT, and that the influence of yaw on the contact results is significant under certain circumstances.

  8. [The problems of education in otosurgery: the current state-of-the-art].

    PubMed

    Ioannides, G F

    2014-01-01

    An overview of the current problems of education in ear surgery is presented. The methods used for the purpose including the classical dissection of the temporal bone, application of synthetic and natural (animal) temporal bones are described alongside with the 3D models of the temporal bone and virtual dissection. In addition, the review covers the problem of enhancing effectiveness of the teaching methods, considers their advantages and disadvantages.

  9. Non-contact online thickness measurement system for metal films based on eddy current sensing with distance tracking technique.

    PubMed

    Li, Wei; Wang, Hongbo; Feng, Zhihua

    2016-04-01

    This paper proposes an online, non-contact metal film thickness measurement system based on eddy current sensing. The slope of the lift-off curve (LOC) is used for characterizing target thickness. Theoretical derivation was conducted to prove that the slope is independent of the lift-off variation. In practice, the measurement has some immunity to the lift-off, but not perfect. The slope of LOC is still affected at some extent by the lift-off. Hence, a height tracking system was also proposed, which could stabilize the distance between the sensor and the target and significantly reduce the lift-off effect. The height tracking system contains a specially designed probe, which could vibrate rapidly to obtain a fast measurement speed, and its height can be adjusted up and down continuously to stabilize the lift-off. The sensor coil in the thickness measurement system was also used as the height sensor in the height tracking system. Several experiments were conducted to test the system performances under static and dynamic conditions. This measurement system demonstrated significant advantages, such as simple and clear conversion between the slope of LOC and target thickness, high resolution and stability, and minimized effect of lift-off variation.

  10. Non-contact online thickness measurement system for metal films based on eddy current sensing with distance tracking technique

    NASA Astrophysics Data System (ADS)

    Li, Wei; Wang, Hongbo; Feng, Zhihua

    2016-04-01

    This paper proposes an online, non-contact metal film thickness measurement system based on eddy current sensing. The slope of the lift-off curve (LOC) is used for characterizing target thickness. Theoretical derivation was conducted to prove that the slope is independent of the lift-off variation. In practice, the measurement has some immunity to the lift-off, but not perfect. The slope of LOC is still affected at some extent by the lift-off. Hence, a height tracking system was also proposed, which could stabilize the distance between the sensor and the target and significantly reduce the lift-off effect. The height tracking system contains a specially designed probe, which could vibrate rapidly to obtain a fast measurement speed, and its height can be adjusted up and down continuously to stabilize the lift-off. The sensor coil in the thickness measurement system was also used as the height sensor in the height tracking system. Several experiments were conducted to test the system performances under static and dynamic conditions. This measurement system demonstrated significant advantages, such as simple and clear conversion between the slope of LOC and target thickness, high resolution and stability, and minimized effect of lift-off variation.

  11. Non-contact online thickness measurement system for metal films based on eddy current sensing with distance tracking technique.

    PubMed

    Li, Wei; Wang, Hongbo; Feng, Zhihua

    2016-04-01

    This paper proposes an online, non-contact metal film thickness measurement system based on eddy current sensing. The slope of the lift-off curve (LOC) is used for characterizing target thickness. Theoretical derivation was conducted to prove that the slope is independent of the lift-off variation. In practice, the measurement has some immunity to the lift-off, but not perfect. The slope of LOC is still affected at some extent by the lift-off. Hence, a height tracking system was also proposed, which could stabilize the distance between the sensor and the target and significantly reduce the lift-off effect. The height tracking system contains a specially designed probe, which could vibrate rapidly to obtain a fast measurement speed, and its height can be adjusted up and down continuously to stabilize the lift-off. The sensor coil in the thickness measurement system was also used as the height sensor in the height tracking system. Several experiments were conducted to test the system performances under static and dynamic conditions. This measurement system demonstrated significant advantages, such as simple and clear conversion between the slope of LOC and target thickness, high resolution and stability, and minimized effect of lift-off variation. PMID:27131700

  12. Effect of Polya Problem-Solving Model on Senior Secondary School Students' Performance in Current Electricity

    ERIC Educational Resources Information Center

    Olaniyan, Ademola Olatide; Omosewo, Esther O.; Nwankwo, Levi I.

    2015-01-01

    This study was designed to investigate the Effect of Polya Problem-Solving Model on Senior School Students' Performance in Current Electricity. It was a quasi experimental study of non- randomized, non equivalent pre-test post-test control group design. Three research questions were answered and corresponding three research hypotheses were tested…

  13. [Exploring Current Problems and Corresponding Strategies for Evaluation of Innovative Medical Devices in China].

    PubMed

    Du, Ranran; Ouyang, Zhaolian; Li, Yang; Yang, Yuan; Yang, Guozhong; Chi, Hui

    2015-03-01

    Through the analysis of the current status and problems of innovative medical devices evaluation, tnis paper discussed the strategies of evaluation, and ultimately raises the frame of evaluation, so as to provide reference for scientific evaluation of medical devices in China.

  14. Public Library Development in Victoria; Current Problems. A Seminar in Four Sessions.

    ERIC Educational Resources Information Center

    Williams, R. P., Ed.; And Others

    The eight papers included in this anthology were originally presented during the 1968 quarterly meeting of the Public Libraries Section, Victorian Division of the Library Association of Australia. The papers are: (1) Some Current Problems in Public Library Development in Victoria, (2) The Role of Government and Public Libraries, (3) Regional…

  15. Overview of Current Trends in Mental Health Problems for Australia's Youth and Adolescents

    ERIC Educational Resources Information Center

    Rickwood, Debra; White, Angela; Eckersley, Richard

    2007-01-01

    This paper provides an overview of current trends in the mental health problems of Australia's youth and adolescents. It presents information derived from the most recent and comprehensive Australian surveys of youth mental health, and provides international comparisons and views from professional practice where relevant. An update of trends for…

  16. Evaluation of current state of agricultural land using problem-oriented fuzzy indicators in GIS environment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Current state of agricultural lands is defined under influence of processes in soil, plants and atmosphere and is described by observation data, complicated models and subjective opinion of experts. Problem-oriented indicators summarize this information in useful form for decision of the same specif...

  17. Redundant drive current imbalance problem of the Automatic Radiator Inspection Device (ARID)

    NASA Technical Reports Server (NTRS)

    Latino, Carl D.

    1992-01-01

    The Automatic Radiator Inspection Device (ARID) is a 4 Degree of Freedom (DOF) robot with redundant drive motors at each joint. The device is intended to automate the labor intensive task of space shuttle radiator inspection. For safety and redundancy, each joint is driven by two independent motor systems. Motors driving the same joint, however, draw vastly different currents. The concern was that the robot joints could be subjected to undue stress. It was the objective of this summer's project to determine the cause of this current imbalance. In addition it was to determine, in a quantitative manner, what was the cause, how serious the problem was in terms of damage or undue wear to the robot and find solutions if possible. It was concluded that most problems could be resolved with a better motor control design. This document discusses problems encountered and possible solutions.

  18. Thermal contact resistance measurement of conduction cooled binary current lead joint block in cryocooler based self field I-V characterization facility

    NASA Astrophysics Data System (ADS)

    Kundu, Ananya; Das, Subrat Kumar; Agarwal, Anees Bano Pooja; Pradhan, Subrata

    2016-05-01

    In the present study thermal resistance of conduction cooled current lead joint block employing two different interfacial material namely AlN sheet and Kapton Film have been studied in the temperature range 5K-35K. In each case, the performance of different interlayer materials e.g. Indium foil for moderately pressurized contacts (contact pressure <1 MPa), and Apiezon N Grease, GE varnish for low pressurized contact (contact pressure <1 MPa) is studied. The performances of AlN joint with Indium foil and with Apeizon N Grease are studied and it is observed that the contact resistance reduces more with indium foil as compared to greased contact. The contact resistance measurements of Kapton film with Apiezon N grease and with GE varnish were also carried out in the same temperature range. A comparative study of AlN joint with Indium foil and Kapton with GE varnish as filler material is carried out to demonstrate better candidate material among Kapton and AlN for a particular filler material in the same temperature range.

  19. [Current problems and challenges in the diagnosis and treatment of colorectal cancer in China].

    PubMed

    Wang, Jianping; Wang, Lei

    2014-06-01

    In the past 20 years, researches regarding colorectal cancer have experienced unprecedented boom in China. However, a seris problems have been exposed, including a rapid increase in morbility, the geographical limitations of tumor screening, nonstandard diagnosis and treatment, very limited mechanism researches, and lack of randomized controlled clinical trials with Chinese characteristics. This article puts forward some main emphases of the current work, based on the above problems and challenges, in order to improve the overall level of the diagnosis and treatment of colorectal cancer in China.

  20. Current transport in W and WSI{sub x} ohmic contacts to InGaN and InN

    SciTech Connect

    Vartuli, C.B.; Pearton, S.J.; Abernathy, C.R.

    1997-10-01

    The temperature dependence of the specific contact resistance of W and WSi{sub 0.44} contacts on n{sup +} In{sub 0.65}Ga{sub 0.35}N and InN was measured in the range -50 {degrees}C to 125 {degrees}C. The results were compared to theoretical values for different conduction mechanisms, to further elucidate the conduction mechanism in these contact schemes for all but as-deposited metal to InN where thermionic emission appears to be the dominant mechanism. The contacts were found to produce low specific resistance ohmic contacts to InGaN at room temperature, e{sup c} {approximately} 10{sup -7} {Omega} {center_dot} cm{sup 2} for W and e{sub c} of 4x 10{sup -7} {Omega} {center_dot} cm{sup 2} for WSi{sub x}. InN metallized with W produced ohmic contacts with e{sub c} {approximately} 10{sup -7} {Omega} {center_dot} cm{sup 2} and e{sub c} {approximately} 10{sup -6} {Omega} {center_dot} cm{sup 2} for WSi{sub x} at room temperature.

  1. Fast solver for large scale eddy current non-destructive evaluation problems

    NASA Astrophysics Data System (ADS)

    Lei, Naiguang

    Eddy current testing plays a very important role in non-destructive evaluations of conducting test samples. Based on Faraday's law, an alternating magnetic field source generates induced currents, called eddy currents, in an electrically conducting test specimen. The eddy currents generate induced magnetic fields that oppose the direction of the inducing magnetic field in accordance with Lenz's law. In the presence of discontinuities in material property or defects in the test specimen, the induced eddy current paths are perturbed and the associated magnetic fields can be detected by coils or magnetic field sensors, such as Hall elements or magneto-resistance sensors. Due to the complexity of the test specimen and the inspection environments, the availability of theoretical simulation models is extremely valuable for studying the basic field/flaw interactions in order to obtain a fuller understanding of non-destructive testing phenomena. Theoretical models of the forward problem are also useful for training and validation of automated defect detection systems. Theoretical models generate defect signatures that are expensive to replicate experimentally. In general, modelling methods can be classified into two categories: analytical and numerical. Although analytical approaches offer closed form solution, it is generally not possible to obtain largely due to the complex sample and defect geometries, especially in three-dimensional space. Numerical modelling has become popular with advances in computer technology and computational methods. However, due to the huge time consumption in the case of large scale problems, accelerations/fast solvers are needed to enhance numerical models. This dissertation describes a numerical simulation model for eddy current problems using finite element analysis. Validation of the accuracy of this model is demonstrated via comparison with experimental measurements of steam generator tube wall defects. These simulations generating two

  2. Shoe allergic contact dermatitis.

    PubMed

    Matthys, Erin; Zahir, Amir; Ehrlich, Alison

    2014-01-01

    Foot dermatitis is a widespread condition, affecting men and women of all ages. Because of the location, this condition may present as a debilitating problem to those who have it. Allergic contact dermatitis involving the feet is frequently due to shoes or socks. The allergens that cause shoe dermatitis can be found in any constituent of footwear, including rubber, adhesives, leather, dyes, metals, and medicaments. The goal of treatment is to identify and minimize contact with the offending allergen(s). The lack of product information released from shoe manufacturers and the continually changing trends in footwear present a challenge in treating this condition. The aim of this study is to review the current literature on allergic contact shoe dermatitis; clinical presentation, allergens, patch testing, and management will be discussed. PubMed and MEDLINE databases were used for the search, with a focus on literature updates from the last 15 years.

  3. A practical solution in delineating thin conducting structures and suppression problem in direct current resistivity sounding

    NASA Astrophysics Data System (ADS)

    Sharma, Shashi Prakash; Biswas, Arkoprovo

    2013-08-01

    In hard rock areas, conventional apparent resistivity measurement using Schlumberger resistivity sounding fails to detect thin conducting structures (2-D and 3-D fractures filled with groundwater and mineral aggregate) concealed at a large depth. In the present study, an attempt is made to way-out the detection problem of deep seated thin conducting layer. It is proposed to study the apparent conductance simultaneously with resistivity sounding to detect such conductive zones qualitatively. Apparent conductance is defined as the magnitude of current flowing in the subsurface for a unit applied voltage through current electrodes. Even though such measurement is of qualitative importance, it gives extremely valuable information for the presence of conductive zones at depth in challenging hard rock terrain. It has been observed that apparent conductance increases significantly when groundwater bearing fractures and conductive bodies are encountered in the subsurface. Field data from different locations are presented to demonstrate the efficacy of such measurement. The measurement assists to the conventional resistivity sounding for successful prediction of groundwater zones at large depth in different hard rock areas and is of enormous importance. The approach is also used for possible solution of suppression problem in the DC resistivity sounding when intermediate layer is not reflected in the resistivity sounding curve. Finally, the approach can be used together with resistivity sounding to solve many practical problems.

  4. Ontological analysis of gene expression data: current tools, limitations, and open problems

    PubMed Central

    Khatri, Purvesh

    2008-01-01

    Summary Independent of the platform and the analysis methods used, the result of a microarray experiment is, in most cases, a list of differentially expressed genes. An automatic ontological analysis approach has been recently proposed to help with the biological interpretation of such results. Currently, this approach is the de facto standard for the secondary analysis of high throughput experiments and a large number of tools have been developed for this purpose. We present a detailed comparison of 14 such tools using the following criteria: scope of the analysis, visualization capabilities, statistical model(s) used, correction for multiple comparisons, reference microar-rays available, installation issues and sources of annotation data. This detailed analysis of the capabilities of these tools will help researchers choose the most appropriate tool for a given type of analysis. More importantly, in spite of the fact that this type of analysis has been generally adopted, this approach has several important intrinsic drawbacks. These drawbacks are associated with all tools discussed and represent conceptual limitations of the current state-of-the-art in ontological analysis. We propose these as challenges for the next generation of secondary data analysis tools. Contact sod@cs.wayne.edu PMID:15994189

  5. Initial and ongoing teacher preparation and support: current problems and possible solutions.

    PubMed

    Johnson, Harold A

    2013-01-01

    The effective initial preparation and ongoing support of teachers of students who are deaf and hard of hearing has always been a difficult and controversial task. Changes in student demographic characteristics and educational settings, combined with the rapidly diminishing number and diversity of deaf education teacher preparation (DETP) programs, indicate that the field of deaf education may be at a tipping point. In the present article, the author establishes the dimensions of the current problems and proposes specific solutions to increase the accessibility and effectiveness of DETP programs that would simultaneously enhance the supply, retention, and instructional effectiveness of teachers of students who are deaf and hard of hearing.

  6. Towards a more accurate microscopic description of the moving contact line problem - incorporating nonlocal effects through a statistical mechanics framework

    NASA Astrophysics Data System (ADS)

    Nold, Andreas; Goddard, Ben; Sibley, David; Kalliadasis, Serafim

    2014-03-01

    Multiscale effects play a predominant role in wetting phenomena such as the moving contact line. An accurate description is of paramount interest for a wide range of industrial applications, yet it is a matter of ongoing research, due to the difficulty of incorporating different physical effects in one model. Important small-scale phenomena are corrections to the attractive fluid-fluid and wall-fluid forces in inhomogeneous density distributions, which often previously have been accounted for by the disjoining pressure in an ad-hoc manner. We systematically derive a novel model for the description of a single-component liquid-vapor multiphase system which inherently incorporates these nonlocal effects. This derivation, which is inspired by statistical mechanics in the framework of colloidal density functional theory, is critically discussed with respect to its assumptions and restrictions. The model is then employed numerically to study a moving contact line of a liquid fluid displacing its vapor phase. We show how nonlocal physical effects are inherently incorporated by the model and describe how classical macroscopic results for the contact line motion are retrieved. We acknowledge financial support from ERC Advanced Grant No. 247031 and Imperial College through a DTG International Studentship.

  7. Colored Contact Lens Dangers

    MedlinePlus

    ... Halloween Hazard: The Hidden Dangers of Buying Decorative Contact Lenses Without a Prescription Sep. 26, 2013 It ... the truth." Real People, Real Problems with Colored Contact Lenses Julian: Teenager Blinded In One Eye By ...

  8. Current Crisis in Science Education? Women in Science and Problems for the Behavioral Scientists. Some Perspectives of a Physicist.

    ERIC Educational Resources Information Center

    Dresselhaus, Mildred S.

    A number of problems exist in society which require the cooperation of physical and social scientists. One of these problems is the current crisis in science education. There are several aspects to this problem, including the declining interest of students in math and science at a time when functioning in our society requires more, not less,…

  9. The Problems with Problem Solving: Reflections on the Rise, Current Status, and Possible Future of a Cognitive Research Paradigm

    ERIC Educational Resources Information Center

    Ohlsson, Stellan

    2012-01-01

    The research paradigm invented by Allen Newell and Herbert A. Simon in the late 1950s dominated the study of problem solving for more than three decades. But in the early 1990s, problem solving ceased to drive research on complex cognition. As part of this decline, Newell and Simon's most innovative research practices--especially their method for…

  10. Using reciprocity for relating the simulation of transcranial current stimulation to the EEG forward problem.

    PubMed

    Wagner, S; Lucka, F; Vorwerk, J; Herrmann, C S; Nolte, G; Burger, M; Wolters, C H

    2016-10-15

    To explore the relationship between transcranial current stimulation (tCS) and the electroencephalography (EEG) forward problem, we investigate and compare accuracy and efficiency of a reciprocal and a direct EEG forward approach for dipolar primary current sources both based on the finite element method (FEM), namely the adjoint approach (AA) and the partial integration approach in conjunction with a transfer matrix concept (PI). By analyzing numerical results, comparing to analytically derived EEG forward potentials and estimating computational complexity in spherical shell models, AA turns out to be essentially identical to PI. It is then proven that AA and PI are also algebraically identical even for general head models. This relation offers a direct link between the EEG forward problem and tCS. We then demonstrate how the quasi-analytical EEG forward solutions in sphere models can be used to validate the numerical accuracies of FEM-based tCS simulation approaches. These approaches differ with respect to the ease with which they can be employed for realistic head modeling based on MRI-derived segmentations. We show that while the accuracy of the most easy to realize approach based on regular hexahedral elements is already quite high, it can be significantly improved if a geometry-adaptation of the elements is employed in conjunction with an isoparametric FEM approach. While the latter approach does not involve any additional difficulties for the user, it reaches the high accuracies of surface-segmentation based tetrahedral FEM, which is considerably more difficult to implement and topologically less flexible in practice. Finally, in a highly realistic head volume conductor model and when compared to the regular alternative, the geometry-adapted hexahedral FEM is shown to result in significant changes in tCS current flow orientation and magnitude up to 45° and a factor of 1.66, respectively. PMID:27125841

  11. Current status of the development of the problem-oriented software package GYREOSS

    NASA Astrophysics Data System (ADS)

    Damyanova, M.; Sabchevski, S.; Zhelyazkov, I.; Vasileva, E.; Balabanova, E.; Dankov, P.; Malinov, P.

    2014-05-01

    A great number of problem-oriented software packages (e.g., DAPHNE, ESRAY, GYROSIM, just to name a few) are used for computer-aided design (CAD) and optimization of high-power gyrotrons for fusion research (most notably for ECRH and ECCD). In them, adequate self-consistent physical models formulated in a two-dimensional space (2D) are implemented. Most of the problems encountered in recent years in the development of megawatt-class gyrotrons, however, can be attributed to physical factors and phenomena that are both non-stationary (for instance various electron beam instabilities, dynamics of the trapped particles) and inherently three-dimensional by nature (e.g., non-uniformity of the emission, misalignment of the electrodes and magnetic coils, etc.). In order to address these problems and to take into account most of the physical factors that have so far been neglected, a work on the development of a novel problem-oriented software package called GYREOSS (which stands for Gyrotron Electron-Optical System Simulation) was initiated recently. Since then, GYREOSS has evolved into a test bed for experimenting with different numerical methods, algorithms, and programming techniques for ray tracing (trajectory analysis) and particle-in-cell (PIC) simulations. In this paper, we outline the current status of GYREOSS and present both its physical model formulated in 2D and 3D and its program realization. We illustrate the capabilities of the latest version of the code, which includes a novel 3D field solver and an efficient relativistic particle pusher. Finally, we present an outlook for a further development of GYREOSS.

  12. Numerical analysis of some problems related to the mechanics of pneumatic tires: Finite deformation/rolling contact of a viscoelastic cylinder and finite deformation of cord-reinforced rubber composites

    NASA Technical Reports Server (NTRS)

    Oden, J. T.; Becker, E. B.; Lin, T. L.; Hsieh, K. T.

    1984-01-01

    The formulation and numerical analysis of several problems related to the behavior of pneumatic tires are considered. These problems include the general rolling contact problem of a rubber-like viscoelastic cylinder undergoing finite deformations and the finite deformation of cord-reinforced rubber composites. New finite element models are developed for these problems. Numerical results obtained for several representative cases are presented.

  13. A discrete geometric formulation for eddy-current problems in fusion devices

    NASA Astrophysics Data System (ADS)

    Bettini, Paolo; Furno Palumbo, Maurizio; Specogna, Ruben

    2014-03-01

    All thermonuclear controlled fusion devices under construction or design have such high performances to require a special care in the dimensioning of various components, specifically from the electromagnetic point of view. To this purpose, it is fundamental to develop models which are both accurate (i.e. able to describe the physical phenomena) and predictive (i.e. useful not only to explain what happens in running experiments, but also to reliably extrapolate to other range of parameters). The dynamics of fusion plasmas is often conveniently described by Magneto-Hydro-Dynamics (MHD) equations, which predict that some unstable evolution modes may exist. On the other hand, the complexity of the intrinsically 3D model of the interactions between a realistic unstable plasma, the surrounding passive structures (important to guarantee a good MHD stability) and the active conductors (coils) require the numerical solution of challenging electromagnetic problems. In this work a discrete geometric formulation for eddy-current problems in the frequency domain is developed; the magnetic fields produced by a typical active coil system is calculated in the presence of 3D conductive structures.

  14. Current problems in national hospitals of Phnom Penh: finance and health care.

    PubMed

    Uy, Sophoat; Akashi, Hidechika; Taki, Kazumi; Ito, Katsuki

    2007-01-01

    The current problems in Cambodia's national hospitals subsist in a geographic imbalance in the location of staff and health facilities, and low staff motivation largely due to inadequate payment. This paper aims to investigate the associations among hospital performance, hospital finances, and other related issues in five national hospitals in Phnom Penh, using annual reports of the five hospitals and annual statistics of the Ministry of Health, from 2000 to 2004. The bed occupancy rates (BOR), average lengths of stay (ALS), hospital mortality rates (HMR), maternal and neonatal mortality rates, numbers of patients, main health problems of inpatients, numbers of health personnel, staff incentives, and annual hospital income were used in this study as indicators of five hospitals in Phnom Penh city. The ALS varied from 3.8 to 9 days. The numbers of health personnel (physician, medical assistant, secondary nurses, primary nurses, secondary midwives, and primary midwives) per 100 beds were from 114 to 282. Supplemental salary per staff also differed greatly among these hospitals; the salaries were the highest at Calmette hospital (US$ 212.8) and the lowest at Preah Kossamak (US$ 12.4). In the five hospitals, the average BOR was 58.8%, and the mean of total annual income was US$ 1,427,852 per year. Although not significant, there was a tendency for higher supplemental salaries to be associated with higher BOR (Spearman rank correlation coefficient 0.70, p = 0.188). This study showed the differences in the hospital indicators among five national hospitals in Phnom Penh city, and the tendency of higher BOR in the hospitals paying higher supplemental salaries to the staff. Higher supplemental salary to the staff seemed to contribute the better hospital performance. PMID:17378183

  15. Health and safety problems associated with long working hours: a review of the current position.

    PubMed Central

    Spurgeon, A; Harrington, J M; Cooper, C L

    1997-01-01

    The European Community Directive on Working Time, which should have been implemented in member states of the European Community by November 1996, contains several requirements related to working hours, including the right of employees to refuse to work more than 48 hours a week. The United Kingdom government attempted to oppose the Directive, arguing that there is no convincing evidence that hours of work should be limited on health and safety grounds. Much of the research in this area has focused on the problems of shiftworking and previous reviews have therefore tended to emphasise this aspect of working hours. However, there is much less information about the effects of overtime work, which is a central element of the terms of the Directive. This paper reviews the current evidence relating to the potential effects on health and performance of extensions to the normal working day. Several gaps in the literature are identified. Research to date has been restricted to a limited range of health outcomes--namely, mental health and cardiovascular disorders. Other potential effects which are normally associated with stress--for example, gastrointestinal disorders, musculoskeletal disorders, and problems associated with depression of the immune system, have received little attention. Also, there have been few systematic investigations of performance effects, and little consideration of the implications for occupational exposure limits of extensions to the working day. Existing data relate largely to situations where working hours exceed 50 a week and there is a lack of information on hours below this level, which is of direct relevance to the European Community proposal. Finally, it is clear from investigations relating to shiftwork that a range of modifying factors are likely to influence the level and nature of health and performance outcomes. These include the attitudes and motivation of the people concerned, the job requirements, and other aspects of the

  16. A Model of an Electrical Discharge in the Flance Contacts With Omega Seals at High Currents in PEP-II

    SciTech Connect

    Novokhatski, A; Seeman, J.; Sullivan, M.; /SLAC

    2008-07-11

    During PEP-II operation with high currents in the High Energy Ring (HER), elevated temperatures were found at many locations in the vacuum chamber where they have an RF seal for the flex flange. Most of these omega RF seals were badly damaged and had evidence of metal vaporization from sparks and electrical discharge. They suggest a physical model, which may explain this effect.

  17. A Survey on Renewable Energy Development in Malaysia: Current Status, Problems and Prospects

    NASA Astrophysics Data System (ADS)

    Alam, Syed Shah; Nor, Nor Fariza Mohd; Ahmad, Maisarah; Hashim, Nik Hazrul Nik

    2016-05-01

    Energy demand in Malaysia is increasing over seven per cent a year, while forty per cent of the energy is supplied from conventional fossil fuel. However, a number of social barriers have mired the social acceptance of renewable energy among the users. This study investigates the current status of renewable energy, problems and future outlook of renewable energy in Malaysia. A total of 200 respondents were surveyed from Klang Valley in Malaysia. Majority of the respondents use energy to generate electricity. Although some respondents reported using solar energy, there is lack of retail availability for solar energy. The findings show that limited information on renewable energy technologies, lack of awareness, and limited private sector engagement emerged as major barriers to sustainable renewable energy development. In addition, the respondents suggest for increasing policy support from the government to make information more accessible to mass users, provide economic incentives to investors and users, and promote small-community based renewable energy projects. The study suggests that the government begin small scale projects to build awareness on renewable energy, while academically, higher learning institutions include renewable energy syllabus in their academic curriculum. The study concluded that to have sustainable renewable energy development, government's initiative, private sector engagement and users awareness must be given priority.

  18. Current problems concerning parasitology and mycology with regard to diseases of the skin and its appendages.

    PubMed

    Błaszkowska, Joanna; Wójcik, Anna

    2012-01-01

    Current issues concerning Parasitology and Mycology with regard to diseases of the skin and its appendages are presented. Aspects of diagnostics, clinical picture and therapy of skin and nail mycoses, as well as difficulties in the diagnosis and treatment of both native parasitoses (toxoplasmosis) and imported human tropical parasitoses (malaria, filariosis) have been emphasised. The clinical importance of environmental mould fungi in nosocomial infections and fungal meningitis, as well as selected properties of fungi isolated from patients with head and neck neoplasms treated by radiotherapy are discussed. Other mycological topics include the characteristics of newly-synthesized thiosemicarbazides and thiadiazoles as potential drugs against toxoplasmosis and their biological activity against Toxoplasma gondii tachyzoites, selected molecular mechanisms of resistance to azoles, Candida albicans strains and a new tool (barcoding DNA) for describing the biodiversity of potential allergenic molds. The importance of environmental factors in pathogenesis of mycoses and parasitoses is noted. The characteristics of pathogenic fungi isolated from natural ponds in Bialystok and potentially pathogenic yeast-like fungi isolated from children's recreation areas in Lodz are presented. The ongoing problem of anthropozoonoses is considered, as are the roles of stray cats and dogs in contaminating soil with the developing forms of intestinal parasites. The characteristics of the human microbiome, including population composition, activity and their importance in normal human physiology, are presented, as are the major goals of the Human Microbiome Project initiated by National Institutes of Health (NIH). PMID:23444796

  19. Current problems concerning parasitology and mycology with regard to diseases of the skin and its appendages.

    PubMed

    Błaszkowska, Joanna; Wójcik, Anna

    2012-01-01

    Current issues concerning Parasitology and Mycology with regard to diseases of the skin and its appendages are presented. Aspects of diagnostics, clinical picture and therapy of skin and nail mycoses, as well as difficulties in the diagnosis and treatment of both native parasitoses (toxoplasmosis) and imported human tropical parasitoses (malaria, filariosis) have been emphasised. The clinical importance of environmental mould fungi in nosocomial infections and fungal meningitis, as well as selected properties of fungi isolated from patients with head and neck neoplasms treated by radiotherapy are discussed. Other mycological topics include the characteristics of newly-synthesized thiosemicarbazides and thiadiazoles as potential drugs against toxoplasmosis and their biological activity against Toxoplasma gondii tachyzoites, selected molecular mechanisms of resistance to azoles, Candida albicans strains and a new tool (barcoding DNA) for describing the biodiversity of potential allergenic molds. The importance of environmental factors in pathogenesis of mycoses and parasitoses is noted. The characteristics of pathogenic fungi isolated from natural ponds in Bialystok and potentially pathogenic yeast-like fungi isolated from children's recreation areas in Lodz are presented. The ongoing problem of anthropozoonoses is considered, as are the roles of stray cats and dogs in contaminating soil with the developing forms of intestinal parasites. The characteristics of the human microbiome, including population composition, activity and their importance in normal human physiology, are presented, as are the major goals of the Human Microbiome Project initiated by National Institutes of Health (NIH).

  20. Methodological aspects of current problems in target-based anticancer drug development.

    PubMed

    Yamanaka, Takeharu; Okamoto, Tatsuro; Ichinose, Yukito; Oda, Shinya; Maehara, Yoshihiko

    2006-06-01

    Differently from the conventional antineoplastic agents, target-based drugs are designed a priori, based on our knowledge of various physiological molecules that has been obtained by the development of molecular biology. This "Copernican revolution" in drug development may imply a paradigm shift in this field. However, contrary to the initial expectations, many drugs developed by this approach are now faced with difficulties, mainly because of the fundamental and theoretical limits of this approach. All of the physiological functions are not always known in all target molecules. In low-molecular-weight drugs, i.e., "inhibitors," targets disperse, due to the structural similarities in physiological molecules. This double-faced "out-of-focusing" causes many problems in various steps of drug development, drug design, clinical trials, and administration to patients. Many drugs are now being abandoned because of unexpectedly lower response rates or unforeseeable adverse effects, and the variety of the drugs exhibits a kaleidoscopic appearance. The double-faced "out-of-focusing" derives from the methodological limits in molecular biology, i.e., elementalism, and limits in our techniques for drug development. To overcome these currently inevitable limits, it appears essential to elucidate the specific changes in target molecules that chiefly promote tumor growth and, consequently, strongly predict response to the administered drugs. Precise and efficient detection of responder populations is the key to the development and establishment of target-based anticancer therapies. PMID:16850122

  1. A comprehensive study of charge trapping in organic field-effect devices with promising semiconductors and different contact metals by displacement current measurements

    NASA Astrophysics Data System (ADS)

    Bisoyi, Sibani; Rödel, Reinhold; Zschieschang, Ute; Kang, Myeong Jin; Takimiya, Kazuo; Klauk, Hagen; Tiwari, Shree Prakash

    2016-02-01

    A systematic and comprehensive study on the charge-carrier injection and trapping behavior was performed using displacement current measurements in long-channel capacitors based on four promising small-molecule organic semiconductors (pentacene, DNTT, C10-DNTT and DPh-DNTT). In thin-film transistors, these semiconductors showed charge-carrier mobilities ranging from 1.0 to 7.8 cm2 V-1 s-1. The number of charges injected into and extracted from the semiconductor and the density of charges trapped in the device during each measurement were calculated from the displacement current characteristics and it was found that the density of trapped charges is very similar in all devices and of the order 1012 cm-2, despite the fact that the four semiconductors show significantly different charge-carrier mobilities. The choice of the contact metal (Au, Ag, Cu, Pd) was also found to have no significant effect on the trapping behavior.

  2. Effects of electrical voltage/current on farm animals: How to detect and remedy problems. Agriculture handbook

    SciTech Connect

    Lefcourt, A.M.

    1991-12-01

    The handbook examines (1) the history of stray voltage/current problems on farms, (2) the physical and electrical sources of stray voltage/current phenomena, (3) the physiological and behavioral bases for losses in milk production, (4) methods for identifying and detecting stray voltage/current problems, (5) methods for mitigating such problems, and (6) areas where further research may be warranted. While the primary emphasis is on cattle and dairy farms, the theories and procedures discussed are completely relevant to all types of livestock and livestock housing facilities. Recommendations are made for action levels and concerning mitigation techniques. The fundamental conclusion of the handbook is that stray voltages/currents can be reduced to acceptable levels.

  3. Contact Interface Verification for DYNA3D Scenario 1: Basic Contact

    SciTech Connect

    McMichael, L D

    2006-05-10

    A suite of test problems has been developed to examine contact behavior within the nonlinear, three-dimensional, explicit finite element analysis (FEA) code DYNA3D (Lin, 2005). The test problems address the basic functionality of the contact algorithms, including the behavior of various kinematic, penalty, and Lagrangian enforcement formulations. The results from the DYNA3D analyses are compared to closed form solutions to verify the contact behavior. This work was performed as part of the Verification and Validation efforts of LLNL W Program within the NNSA's Advanced Simulation and Computing (ASC) Program. DYNA3D models the transient dynamic response of solids and structures including the interactions between disjoint bodies (parts). A wide variety of contact surfaces are available to represent the diverse interactions possible during an analysis, including relative motion (sliding), separation and gap closure (voids), and fixed relative position (tied). The problem geometry may be defined using a combination of element formulations, including one-dimensional beam and truss elements, two-dimensional shell elements, and three-dimensional solid elements. Consequently, it is necessary to consider various element interactions for each contact algorithm being verified. Most of the contact algorithms currently available in DYNA3D are examined; the exceptions are the Type 4--Single Surface Contact and Type 11--SAND algorithms. It is likely that these algorithms will be removed since their functionality is embodied in other, more robust, contact algorithms. The automatic contact algorithm is evaluated using the Type 12 interface. Two other variations of automatic contact, Type 13 and Type 14, offer additional means to adapt the interface domain, but share the same search and restoration algorithms as Type 12. The contact algorithms are summarized in Table 1. This report and associated test problems examine the scenario where one contact surface exists between two

  4. [Current problems of hospital health including the AIDS problem. "Protection of patients and staff--legal status"].

    PubMed

    Gallwas, H U

    1989-01-01

    The prevention of HIV infection in hospital, if at all possible, is a general legal obligation. For that reason, special preventive measures against infection are required for blood transfusions, transplantations or semen donations. On the other hand, comprehensive information on the risks of infection and the permanent reminder of hygienic directions are considered to be sufficient for the protection of physicians and nursing staffs. However, the arguments for such a careless handling are not convincing. HIV testing of patients for the protection of the medical staff must not be relinquished. However, the current jurisdiction does not permit to carry out HIV tests without the patients' consent following comprehensive information; furthermore, the consequences resulting from a positive as well as a negative test have to be explained to the patients. In case of established infection further transmission must be prevented by all means.

  5. Contact solution algorithms

    NASA Technical Reports Server (NTRS)

    Tielking, John T.

    1989-01-01

    Two algorithms for obtaining static contact solutions are described in this presentation. Although they were derived for contact problems involving specific structures (a tire and a solid rubber cylinder), they are sufficiently general to be applied to other shell-of-revolution and solid-body contact problems. The shell-of-revolution contact algorithm is a method of obtaining a point load influence coefficient matrix for the portion of shell surface that is expected to carry a contact load. If the shell is sufficiently linear with respect to contact loading, a single influence coefficient matrix can be used to obtain a good approximation of the contact pressure distribution. Otherwise, the matrix will be updated to reflect nonlinear load-deflection behavior. The solid-body contact algorithm utilizes a Lagrange multiplier to include the contact constraint in a potential energy functional. The solution is found by applying the principle of minimum potential energy. The Lagrange multiplier is identified as the contact load resultant for a specific deflection. At present, only frictionless contact solutions have been obtained with these algorithms. A sliding tread element has been developed to calculate friction shear force in the contact region of the rolling shell-of-revolution tire model.

  6. A Problem-Solving Approach to Addressing Current Global Challenges in Education

    ERIC Educational Resources Information Center

    Chapman, Judith D.; Aspin, David N.

    2013-01-01

    This paper begins with an analysis of global problems shaping education, particularly as they impact upon learning and life chances. In addressing these problems a range of philosophical positions and controversies are considered, including: traditional romantic and institutional views of schooling; and more recent maximalist, neo-liberal,…

  7. Contact Dermatitis

    MedlinePlus

    ... care Kids’ zone Video library Find a dermatologist Contact dermatitis Overview Contact dermatitis: Many health care workers ... to touching her face while wearing latex gloves. Contact dermatitis: Overview Almost everyone gets this type of ...

  8. Language Contact.

    ERIC Educational Resources Information Center

    Nelde, Peter Hans

    1995-01-01

    Examines the phenomenon of language contact and recent trends in linguistic contact research, which focuses on language use, language users, and language spheres. Also discusses the role of linguistic and cultural conflicts in language contact situations. (13 references) (MDM)

  9. Some current problems in perovskite nano-ferroelectrics and multiferroics: kinetically-limited systems of finite lateral size

    NASA Astrophysics Data System (ADS)

    Scott, James F.; Schilling, Alina; Rowley, S. E.; Gregg, J. Marty

    2015-06-01

    We describe some unsolved problems of current interest; these involve quantum critical points in ferroelectrics and problems which are not amenable to the usual density functional theory, nor to classical Landau free energy approaches (they are kinetically limited), nor even to the Landau-Kittel relationship for domain size (they do not satisfy the assumption of infinite lateral diameter) because they are dominated by finite aperiodic boundary conditions.

  10. Ionic liquid gating on atomic layer deposition passivated GaN: Ultra-high electron density induced high drain current and low contact resistance

    NASA Astrophysics Data System (ADS)

    Zhou, Hong; Du, Yuchen; Ye, Peide D.

    2016-05-01

    Herein, we report on achieving ultra-high electron density (exceeding 1014 cm-2) in a GaN bulk material device by ionic liquid gating, through the application of atomic layer deposition (ALD) of Al2O3 to passivate the GaN surface. Output characteristics demonstrate a maximum drain current of 1.47 A/mm, the highest reported among all bulk GaN field-effect transistors, with an on/off ratio of 105 at room temperature. An ultra-high electron density exceeding 1014 cm-2 accumulated at the surface is confirmed via Hall-effect measurement and transfer length measurement. In addition to the ultra-high electron density, we also observe a reduction of the contact resistance due to the narrowing of the Schottky barrier width on the contacts. Taking advantage of the ALD surface passivation and ionic liquid gating technique, this work provides a route to study the field-effect and carrier transport properties of conventional semiconductors in unprecedented ultra-high charge density regions.

  11. Microstructural characterization and current conduction mechanisms of front-side contact of n-type crystalline Si solar cells with Ag/Al pastes

    NASA Astrophysics Data System (ADS)

    Liang, L.; Li, Z. G.; Cheng, L. K.; Takeda, N.; Carroll, A. F.

    2015-06-01

    Recently, high efficiency n-type crystalline Si cells made with the screen printed Ag/Al metallization have received considerable attention. We report here our microstructural investigations of the critical interfacial region between the front-side contact and the Si wafer of n-type cells fired under progressively higher temperatures. Our study revealed that the key characteristic microstructures of the interfacial region changed from one with a large fraction of residual SiNx, to one consisting of a thin glass layer with nano-Ag colloids, and finally to one decorated with Ag and Ag/Al crystallites attached to the emitter surface for cells with under-, optimally-, and over-fired conditions, respectively. We did not find any Al-Si eutectic layer on the emitter surface that would support a silicon dissolution and re-growth mechanism, which is operative in the back surface field formation process for the Al back contact of p-type industrial solar cells. The presence of the SiNx antireflection coating has likely altered the chemistry between Si and Al significantly. The observed microstructures lead us to conclude that the main current conduction mechanism in optimally-fired n-type cells is tunneling through those areas of thin interfacial glass containing nano-Ag colloids. This mechanism is similar to the current conduction model we have proposed previously for optimally-fired p-type crystalline Si solar cells. We believe that the intrusion of Ag/Al (and/or Ag) crystallites into the p+-Si emitter in over-fired cells is one of the major sources of metallization-induced recombination losses, which degrades cell performance.

  12. A Current Review of Multisystemic Therapy: A Social-Ecological Approach to the Treatment of Conduct Problems among Adolescents

    ERIC Educational Resources Information Center

    Harpell, Jody V.; Andrews, Jac

    2006-01-01

    A current empirical review of the treatment efficacy of Multisystemic Therapy (MST) for adolescent conduct problems (CP) was conducted. Conclusions based on this review suggest that MST can be a very powerful alternative to the usual legal and social service approaches (e.g. justice system, day treatment programs) used in the treatment of…

  13. Sleep Problems in Children with Attention Deficit/Hyperactivity Disorder: Current Status of Knowledge and Appropriate Management.

    PubMed

    Tsai, Ming-Horng; Hsu, Jen-Fu; Huang, Yu-Shu

    2016-08-01

    Attention deficit hyperactivity disorder (ADHD) affects approximately 5 % of children and adolescents, and sleep problems are common in these patients. There is growing evidence informing the significant importance of sleep problems in youth with ADHD. The sleep problems in children with ADHD include specific sleep disorders and sleep disturbances due to comorbid psychiatric disorders or ADHD medications. The specific sleep disorders of ADHD children include behaviorally based insomnia, sleep-disordered breathing, and restless legs syndrome/periodic limb movement disorder. Current practices on the management of sleep problems for ADHD children are based mostly on expert consensus, whereas more evidence-based literature can be found only recently. Assessment of the sleep conditions in ADHD children before initiation of pharmacotherapy is the currently recommended guideline, and good sleep hygiene can be considered as the first-line treatment option. In addition to modifying the dose regimens, formulation, or alternative stimulants when sleep problems are encountered in ADHD children, atomoxetine, once daily guanfacine extended release, and melatonin are potential choices for ADHD children with more severe sleep problems. In this review, we aimed to provide the most updated information, preferably based on meta-analyses, systemic review, and randomized controlled trials published in the latest 3 years, in order to be clinically useful for practitioners and clinicians. PMID:27357497

  14. Voltage versus Current, or the Problem of the Chicken and the Egg

    ERIC Educational Resources Information Center

    Silva, Antonio Alberto; Soares, Rolando

    2007-01-01

    In an electric circuit, is it the current that causes the voltage, or the inverse? This is a false dilemma, as shown by an introductory and qualitative approach to a circuit as a system. (Contains 9 figures and 7 footnotes.)

  15. Mutual Inductance Problem for a System Consisting of a Current Sheet and a Thin Metal Plate

    NASA Technical Reports Server (NTRS)

    Fulton, J. P.; Wincheski, B.; Nath, S.; Namkung, M.

    1993-01-01

    Rapid inspection of aircraft structures for flaws is of vital importance to the commercial and defense aircraft industry. In particular, inspecting thin aluminum structures for flaws is the focus of a large scale R&D effort in the nondestructive evaluation (NDE) community. Traditional eddy current methods used today are effective, but require long inspection times. New electromagnetic techniques which monitor the normal component of the magnetic field above a sample due to a sheet of current as the excitation, seem to be promising. This paper is an attempt to understand and analyze the magnetic field distribution due to a current sheet above an aluminum test sample. A simple theoretical model, coupled with a two dimensional finite element model (FEM) and experimental data will be presented in the next few sections. A current sheet above a conducting sample generates eddy currents in the material, while a sensor above the current sheet or in between the two plates monitors the normal component of the magnetic field. A rivet or a surface flaw near a rivet in an aircraft aluminum skin will disturb the magnetic field, which is imaged by the sensor. Initial results showed a strong dependence of the flaw induced normal magnetic field strength on the thickness and conductivity of the current-sheet that could not be accounted for by skin depth attenuation alone. It was believed that the eddy current imaging method explained the dependence of the thickness and conductivity of the flaw induced normal magnetic field. Further investigation, suggested the complexity associated with the mutual inductance of the system needed to be studied. The next section gives an analytical model to better understand the phenomenon.

  16. Analysis of leakage current mechanisms in Pt/Au Schottky contact on Ga-polarity GaN by Frenkel-Poole emission and deep level studies

    SciTech Connect

    Rao, Peta Koteswara; Park, Byungguon; Lee, Sang-Tae; Noh, Young-Kyun; Kim, Moon-Deock; Oh, Jae-Eung

    2011-07-01

    We report the Frenkel-Poole emission in Pt/Au Schottky contact on Ga-polarity GaN grown by molecular beam epitaxy using current-voltage-temperature (I-V-T) characteristics in the temperature ranging from 200 K to 375 K. Using thermionic emission model, the estimated Schottky barrier height is 0.49 eV at 200 K and 0.83 eV at 375 K, respectively, and it is observed that the barrier height increases with increase in temperature. The extracted emission barrier height ({phi}{sub t}) for Ga-polarity GaN Schottky diode by Frenkel-Poole theory is about 0.15 eV. Deep level transient spectroscopy study shows a deep level with activation energy of 0.44 eV, having capture cross-section 6.09 x 10{sup -14} cm{sup 2}, which is located between the metal and semiconductor interface, and trap nature is most probably associated with dislocations in Ga-polarity GaN. The analysis of I-V-T characteristics represents that the leakage current is due to effects of electrical field and temperature on the emission of electron from a trap state near the metal-semiconductor interface into continuum states associated with conductive dislocations in Ga-polarity GaN Schottky diode.

  17. The Current State and Problems of the Prevention of Homelessness and Neglect of Minor Children

    ERIC Educational Resources Information Center

    Vetrov, Iu. P.

    2006-01-01

    One of the most urgent problems of Russian society today remains children's homelessness and neglect. This social phenomenon, which has come about due to a number of factors, is characterized by the following indicators: (1) More than 100,000 children have been left without parental care; and (2) The number of parents who have been stripped of…

  18. Self-Monitoring Interventions for Students with Behavior Problems: A Systematic Review of Current Research

    ERIC Educational Resources Information Center

    Bruhn, Allison; McDaniel, Sara; Kreigh, Christi

    2015-01-01

    Explicitly teaching skills associated with self-determination has been promoted to support students' independence and control over their own lives. This is especially important for students with behavior problems. One self-determination skill or behavior that has been studied widely is self-monitoring. Although multiple reviews of various…

  19. Bully/Victim Problems among Preschool Children: A Review of Current Research Evidence

    ERIC Educational Resources Information Center

    Vlachou, Maria; Andreou, Eleni; Botsoglou, Kafenia; Didaskalou, Eleni

    2011-01-01

    Bullying in schools has been identified as a serious and complex worldwide problem associated with negative short- and long-term effects on children's psychosocial adjustment (Smith 1999; Ttofi and Farrington, "Aggressive Behav" 34(4):352-368, 2008). Entering kindergarten is a crucial developmental step in many children's lives mainly because it…

  20. Current Welfare Problems Facing Horses in Great Britain as Identified by Equine Stakeholders

    PubMed Central

    Horseman, Susan V.; Buller, Henry

    2016-01-01

    Despite growing concerns about the welfare of horses in Great Britain (GB) there has been little surveillance of the welfare status of the horse population. Consequently we have limited knowledge of the range of welfare problems experienced by horses in GB and the situations in which poor welfare occurs. Thirty-one in-depth interviews were conducted with a cross -section of equine stakeholders, in order to explore their perceptions of the welfare problems faced by horses in GB. Welfare problems relating to health, management and riding and training were identified, including horses being under or over weight, stabling 24 hours a day and the inappropriate use of training aids. The interviewees also discussed broader contexts in which they perceived that welfare was compromised. The most commonly discussed context was where horses are kept in unsuitable environments, for example environments with poor grazing. The racing industry and travellers horses were identified as areas of the industry where horse welfare was particularly vulnerable to compromise. Lack of knowledge and financial constraints were perceived to be the root cause of poor welfare by many interviewees. The findings give insight into the range of welfare problems that may be faced by horses in GB, the contexts in which these may occur and their possible causes. Many of the problems identified by the interviewees have undergone limited scientific investigation pointing to areas where further research is likely to be necessary for welfare improvement. The large number of issues identified suggests that some form of prioritisation may be necessary to target research and resources effectively. PMID:27501387

  1. Current Welfare Problems Facing Horses in Great Britain as Identified by Equine Stakeholders.

    PubMed

    Horseman, Susan V; Buller, Henry; Mullan, Siobhan; Whay, Helen R

    2016-01-01

    Despite growing concerns about the welfare of horses in Great Britain (GB) there has been little surveillance of the welfare status of the horse population. Consequently we have limited knowledge of the range of welfare problems experienced by horses in GB and the situations in which poor welfare occurs. Thirty-one in-depth interviews were conducted with a cross -section of equine stakeholders, in order to explore their perceptions of the welfare problems faced by horses in GB. Welfare problems relating to health, management and riding and training were identified, including horses being under or over weight, stabling 24 hours a day and the inappropriate use of training aids. The interviewees also discussed broader contexts in which they perceived that welfare was compromised. The most commonly discussed context was where horses are kept in unsuitable environments, for example environments with poor grazing. The racing industry and travellers horses were identified as areas of the industry where horse welfare was particularly vulnerable to compromise. Lack of knowledge and financial constraints were perceived to be the root cause of poor welfare by many interviewees. The findings give insight into the range of welfare problems that may be faced by horses in GB, the contexts in which these may occur and their possible causes. Many of the problems identified by the interviewees have undergone limited scientific investigation pointing to areas where further research is likely to be necessary for welfare improvement. The large number of issues identified suggests that some form of prioritisation may be necessary to target research and resources effectively. PMID:27501387

  2. BISON Contact Improvements CASL FY14 Report

    SciTech Connect

    B. W. Spencer; J. D. Hales; D. R. Gaston; D. A. Karpeev; R. L. Williamson; S. R. Novascone; D. M. Perez; R. J. Gardner; K. A. Gamble

    2014-09-01

    The BISON code is the foundation for multiple fuel performance modeling efforts, and is cur- rently under heavy development. For a variety of fuel forms, the effects of heat conduction across a gap and mechanical contact between components of a fuel system are very significant. It is thus critical that BISON have robust capabilities for enforcement of thermal and mechanical contact. BISON’s solver robustness has generally been quite good before mechanical contact between the fuel and cladding occurs, but there have been significant challenges obtaining converged so- lutions once that contact occurs and the solver begins to enforce mechanical contact constraints. During the current year, significant development effort has been focused on the enforcement of mechanical contact to provide improved solution robustness. In addition to this work to improve mechanical contact robustness, an investigation into ques- tionable results attributable to thermal contact has been performed. This investigation found that the order of integration typically used on the surfaces involved in thermal contact was not suffi- ciently high. To address this problem, a new option was provided to permit the use of a different integration order for surfaces, and new usage recommendations were provided.

  3. [Current problems in the quality controll of pharmaceutical preparations manufactured in pharmacies I. Identification tests].

    PubMed

    Horváth, Péter; Elekné Vörös, Zsuzsanna; Sinkó, Bálint; Vámos, József; Takácsné Novák, Krisztina

    2006-01-01

    Quality controll has fundamental importance in drug safety. During the last 15 years the regulatory changes resulted many problems in the quality controll of pharmaceutical preparations manufactured in pharmacys. The issue of Formulae Normales (FoNo VII.) and the 8th Hungarian Pharmacopoeia raises further questions. Our intentions to show the results have been achived in the area of elaborating new analytical prescriptions (identification and assay) which are crucial due to the obsolescence of previously used prescriptions.

  4. The Experimental Investigation of the Missing N*- and Δ-RESONANCES Problem:. Current Status and Perspectives

    NASA Astrophysics Data System (ADS)

    Sumachev, V. V.; Bekrenev, V. S.; Beloglazov, Yu. A.; Filimonov, E. A.; Kovalev, A. I.; Kozlenko, N. G.; Kruglov, S. P.; Kulbardis, A. A.; Lopatin, I. V.; Novinsky, D. V.; Shchedrov, V. A.; Trautman, V. Yu.; Alekseev, I. G.; Budkovsky, P. E.; Kanavets, V. P.; Koroleva, L. I.; Morozov, B. V.; Nesterov, V. M.; Ryltsov, V. V.; Sulimov, A. D.; Svirida, D. N.; Bazhanov, N. A.; Bunyatova, E. I.

    2007-11-01

    Numerous attempts to create a model that would exactly reproduce the N* - and Δ - resonances spectrum (that was presented in the Review of Particle Physics) failed. The existing models usually predicted considerably more resonances (twice or more in number) than were found in elastic πN - scattering. This problem is known as the problem of "missing" resonances. The recent partial wave analysis (PWA) SP06 that was made at George Washington University (2006) and included the modern experimental data revealed considerably fewer (approximately half) the N*- and Δ-resonances than those presented in the Review of Particle Physics (RPP) tables (2006). This disagreement invites further experimental investigation of the pion-nucleon interactions. Recent spin rotation parameter A and R measurements of the PNPI and PNPI-ITEP collaborations resolved a part of the twofold ambiguities of the PWA's. These results were used in the last PWA of the George Washington University (GWU) groups. The proposal for the additional measurements of the differential cross section and spin-rotation parameters R and A in the resonance region of the πN interactions is motivated. Such additional experiments are necessary to resolve the problem of the narrow (Γ < 30 MeV) baryon resonances existing and to complete monosemantic PWA of the πN elastic scattering.

  5. Issues and Problems in the Current Development of Vocational Education in China

    ERIC Educational Resources Information Center

    Shi, Weiping

    2013-01-01

    Chinese vocational education is currently in its most optimal development period in history. This article discusses several challenges of different dimensions faced by vocational education in China as it develops, such as scale versus quality, development goals, a lifelong vocational education system, and creating model institutions; and puts…

  6. On the problems of stability and durability of field-emission current sources for electrovacuum devices

    NASA Astrophysics Data System (ADS)

    Yakunin, Alexander N.; Aban'shin, Nikolay P.; Akchurin, Garif G.; Akchurin, Georgy G.; Avetisyan, Yuri A.

    2016-03-01

    The results of the practical implementation of the concept of field-emission current source with high average current density of 0.1-0.3 A-cm-2 are shown. The durability of cathode samples at a level of 6000 hours is achieved under conditions of technical vacuum. A phenomenological model is suggested that describes the tunneling of both equilibrium and nonequilibrium electrons in a vacuum from the zone of concentration of electrostatic field. Conditions are discussed as the resulting increase in the emission current due to the connection mechanism of the photoelectric effect is thermodynamically favorable, that is not accompanied by an undesirable increase in the temperature of the local emission zone. It is shown that to ensure stability and durability of the cathode is also important to limit the concentration of equilibrium carriers using composite structures «DLC film on Mo substrate." This helps to reduce the criticality of the CVC. A possible alternative is to use a restrictive resistance in the cathode. However, this increases the heat losses and thus decreases assembly efficiency. The results of experimental studies of the structure showing the saturation of photoemission current component with an increase in operating voltage. This fact suggests the existence of an effective mechanism for control of emission at constant operating voltage. This is fundamentally important for the stabilization of field emission cathode, providing a reliability and durability. The single-photon processes and the small thickness DLC films (15-20 nm) provide high-speed process of control.

  7. Asthma Management: Part I: An Overview of the Problem and Current Trends.

    ERIC Educational Resources Information Center

    Baker, Valerie O'Toole; Friedman, Janet; Schmitt, Rita

    2002-01-01

    Describes the pathophysiology of asthma and the types, risk factors, and current trends in management of the disease. The role of the school nurse in asthma management is outlined, including identifying children with asthma, evaluating the child's response to the asthma management plan, and controlling environmental factors that precipitate asthma…

  8. Using Adolescent Fiction That Deals with Current Problems and Lifestyles to Explore Contemporary Values.

    ERIC Educational Resources Information Center

    Schwartz, Sheila

    This paper argues that a value structure must be developed and taught in the schools. The values and principles contained in the Humanistic Manifesto II are examined in the context of current adolescent literature. Discussed are such books as "It's Not What You Expect" and "Mom, The Wolfman and Me" by Norma Klein; "First Person Singular" by Vida…

  9. Problems and the potential direction of reforms for the current individual medical savings accounts in the Chinese health care system.

    PubMed

    Kong, Xiangjin; Yang, Yang; Gong, Fuqing; Zhao, Mingjie

    2012-12-01

    Individual health savings accounts are an important part of the current basic medical insurance system for urban workers in China. Since 1998 when the system of personal medical insurance accounts was first implemented, there has been considerable controversy over its function and significance within different social communities. This paper analyzes the main problems in the practical implementation of individual medical insurance accounts and discusses the social and cultural foundations for the establishment of family health savings accounts from the perspective of Chinese Confucian familism. Accordingly, it addresses the direction of the reform and the development of the current system of individual health insurance accounts in China.

  10. [Current situations and problems of quality control for medical imaging display systems].

    PubMed

    Shibutani, Takayuki; Setojima, Tsuyoshi; Ueda, Katsumi; Takada, Katsumi; Okuno, Teiichi; Onoguchi, Masahisa; Nakajima, Tadashi; Fujisawa, Ichiro

    2015-04-01

    Diagnostic imaging has been shifted rapidly from film to monitor diagnostic. Consequently, Japan medical imaging and radiological systems industries association (JIRA) have recommended methods of quality control (QC) for medical imaging display systems. However, in spite of its need by majority of people, executing rate is low. The purpose of this study was to validate the problem including check items about QC for medical imaging display systems. We performed acceptance test of medical imaging display monitors based on Japanese engineering standards of radiological apparatus (JESRA) X-0093*A-2005 to 2009, and performed constancy test based on JESRA X-0093*A-2010 from 2010 to 2012. Furthermore, we investigated the cause of trouble and repaired number. Medical imaging display monitors had 23 inappropriate monitors about visual estimation, and all these monitors were not criteria of JESRA about luminance uniformity. Max luminance was significantly lower year-by-year about measurement estimation, and the 29 monitors did not meet the criteria of JESRA about luminance deviation. Repaired number of medical imaging display monitors had 25, and the cause was failure liquid crystal panel. We suggested the problems about medical imaging display systems.

  11. Current treatment of chronic hepatitis C in China: Dilemma and potential problems

    PubMed Central

    Han, Qun-Ying; Liu, Zheng-Wen

    2016-01-01

    Major advances have been made in the treatment of chronic hepatitis C virus (HCV) infection with the advent of direct-acting antiviral agents (DAAs). China has the most cases of HCV infection worldwide, but none of the DAAs has been approved in mainland China so far, and interferon (IFN)-α-based treatment remains the standard of care. HCV patients without response or with contraindications to IFN-based therapy have no alternative options. However, many patients buy DAAs, especially the generic forms of sofosbuvir, from other countries or areas. Under these circumstances, the use of these drugs may cause many predictable and unpredictable problems in ethics, law and medical practice. Given the obstacles of legal accessibility to DAAs and the potential problems of obtaining and using DAAs in China, the early launching of the DAAs in China or the legalization of buying drugs from areas outside China and using these drugs in China is an urgent issue and needs to be dealt with as soon as possible, in the interest of the patients. PMID:27217693

  12. Radioimmunodetection of cancer with monoclonal antibodies: current status, problems, and future directions

    SciTech Connect

    Murray, J.L.; Unger, M.W.

    1988-01-01

    Early studies of immunoscintography with affinity-purified /sup 131/I-labeled polyclonal antibodies reactive against oncofetal antigens such as carcinoembryonic antigen (CEA) were moderately successful in detecting metastatic colorectal carcinoma. However, because of low tumor to background ratios of isotope, background subtraction techniques using /sup 99/Tc-labeled albumin were required to visualize small lesions. Antisera were often of low titer and lacked specificity. These problems could be overcome for the most part following the development of highly specific monoclonal antibodies (MoAb) against a variety of tumor-associated antigens. A number of clinical trials using /sup 131/I- or /sup 111/In-labeled MoAb to image tumors have demonstrated successful localization without the use of subtraction techniques. Variables limiting the usefulness of murine MoAb for diagnosis have included increased localization in liver and spleen, tumor vascularity and heterogeneity of antigen expression, and development of human antimurine globulins. Methods to overcome some of these problems are discussed. Radiolabeled MoAb appear useful as an adjunct to conventional diagnostic techniques both as a means to predict which antibodies might be useful for treatment and, in select patients, as a basis for treatment decisions. 163 references.

  13. Novel method for rapid in-situ hybridization of HER2 using non-contact alternating-current electric-field mixing

    PubMed Central

    Saito, Yoshitaro; Imai, Kazuhiro; Nakamura, Ryuta; Nanjo, Hiroshi; Terata, Kaori; Konno, Hayato; Akagami, Yoichi; Minamiya, Yoshihiro

    2016-01-01

    Human epidermal growth factor receptor 2 (HER2)-targeted agents are an effective approach to treating HER2-positive breast cancer patients. However, the lack of survival benefit in HER2-negative patients as well as the toxic effects and high cost of the drugs highlight the need for accurate and prompt assessment of HER2 status. Our aim was to evaluate the clinical utility of a novel rapid dual in-situ hybridization (RISH) method developed to facilitate hybridization. The method takes advantage of the non-contact mixing effect of an alternating current (AC) electric field. One hundred sixty-three specimens were used from patients diagnosed with primary breast cancers identified immunohistochemically as HER2 0/1(+), (2+) or (3+). The specimens were all tested using conventional dual in-situ hybridization (DISH), DISH with an automated slide stainer, and RISH. With RISH the HER2 test was completed within 6 h, as compared to 20–22 h needed for the standard protocol. Although RISH produced results more promptly using smaller amounts of labeled antibody, the staining and accuracy of HER2 status evaluation with RISH was equal to or greater than with DISH. These results suggest RISH could be used as a clinical tool to promptly determine HER2 status. PMID:27443187

  14. Novel method for rapid in-situ hybridization of HER2 using non-contact alternating-current electric-field mixing.

    PubMed

    Saito, Yoshitaro; Imai, Kazuhiro; Nakamura, Ryuta; Nanjo, Hiroshi; Terata, Kaori; Konno, Hayato; Akagami, Yoichi; Minamiya, Yoshihiro

    2016-01-01

    Human epidermal growth factor receptor 2 (HER2)-targeted agents are an effective approach to treating HER2-positive breast cancer patients. However, the lack of survival benefit in HER2-negative patients as well as the toxic effects and high cost of the drugs highlight the need for accurate and prompt assessment of HER2 status. Our aim was to evaluate the clinical utility of a novel rapid dual in-situ hybridization (RISH) method developed to facilitate hybridization. The method takes advantage of the non-contact mixing effect of an alternating current (AC) electric field. One hundred sixty-three specimens were used from patients diagnosed with primary breast cancers identified immunohistochemically as HER2 0/1(+), (2+) or (3+). The specimens were all tested using conventional dual in-situ hybridization (DISH), DISH with an automated slide stainer, and RISH. With RISH the HER2 test was completed within 6 h, as compared to 20-22 h needed for the standard protocol. Although RISH produced results more promptly using smaller amounts of labeled antibody, the staining and accuracy of HER2 status evaluation with RISH was equal to or greater than with DISH. These results suggest RISH could be used as a clinical tool to promptly determine HER2 status. PMID:27443187

  15. High-Performance Computing and Four-Dimensional Data Assimilation: The Impact on Future and Current Problems

    NASA Technical Reports Server (NTRS)

    Makivic, Miloje S.

    1996-01-01

    This is the final technical report for the project entitled: "High-Performance Computing and Four-Dimensional Data Assimilation: The Impact on Future and Current Problems", funded at NPAC by the DAO at NASA/GSFC. First, the motivation for the project is given in the introductory section, followed by the executive summary of major accomplishments and the list of project-related publications. Detailed analysis and description of research results is given in subsequent chapters and in the Appendix.

  16. Presymplectic current and the inverse problem of the calculus of variations

    SciTech Connect

    Khavkine, Igor

    2013-11-15

    The inverse problem of the calculus of variations asks whether a given system of partial differential equations (PDEs) admits a variational formulation. We show that the existence of a presymplectic form in the variational bicomplex, when horizontally closed on solutions, allows us to construct a variational formulation for a subsystem of the given PDE. No constraints on the differential order or number of dependent or independent variables are assumed. The proof follows a recent observation of Bridges, Hydon, and Lawson [Math. Proc. Cambridge Philos. Soc. 148(01), 159–178 (2010)] and generalizes an older result of Henneaux [Ann. Phys. 140(1), 45–64 (1982)] from ordinary differential equations (ODEs) to PDEs. Uniqueness of the variational formulation is also discussed.

  17. Presymplectic current and the inverse problem of the calculus of variations

    NASA Astrophysics Data System (ADS)

    Khavkine, Igor

    2013-11-01

    The inverse problem of the calculus of variations asks whether a given system of partial differential equations (PDEs) admits a variational formulation. We show that the existence of a presymplectic form in the variational bicomplex, when horizontally closed on solutions, allows us to construct a variational formulation for a subsystem of the given PDE. No constraints on the differential order or number of dependent or independent variables are assumed. The proof follows a recent observation of Bridges, Hydon, and Lawson [Math. Proc. Cambridge Philos. Soc. 148(01), 159-178 (2010)] and generalizes an older result of Henneaux [Ann. Phys. 140(1), 45-64 (1982)] from ordinary differential equations (ODEs) to PDEs. Uniqueness of the variational formulation is also discussed.

  18. [Current problems in the pathological anatomy of acute neuroinfections in children].

    PubMed

    Tsinzerling, V A

    1985-01-01

    The analysis of the autopsy material of children dying from acute neuroinfections in a specialized department of the Research Institute of Children's Infections from 1954 to 1984 is presented. The increase of the importance of hypertoxic forms of meningococcal infection, purulent meningoencephalitis (particularly those of pneumococcal etiology) as well as acute viral encephalitis (particularly herpetic ones) is noted at present. The results of the materials studied by the author from 182 children dying of those infections at the period from 1971 to 1984, the problems of their patho- and tanatogenesis are discussed. Special attention is drawn to the necessity of considering the type of an etiological agent, its properties, the features of tissue response and those of the immunological resistance in the brain for the diagnosis and epicritic assessment of acute neuroinfections.

  19. Environmental problems in the People`s Republic of China: Current magnitude and possible control options

    SciTech Connect

    Bhadtti, N.; Biang, C.A.; Poch, L.A.; Tompkins, M.M.

    1995-09-01

    The People`s Republic of China has been undergoing rapid economic development over the past several decades. This development has taken place with little or no attention being paid to its environmental consequences. This situation has resulted in severe contamination of the air, water, and soil resources of China, with attendant damage to human and natural populations. This report determines the major causes of air, water, and soil pollution in China and assesses their extent and magnitude. It then examines the impacts of the pollutants on various components of the human and natural environment. It identifies possible regulatory and ameliorative options available to China to deal with these pollution problems and provides information on specific strategies and the costs associated with their implementation. The objective is to shed light on China`s pollution control and remediation requirements in the near future.

  20. Current challenges for confronting the public health problem of snakebite envenoming in Central America.

    PubMed

    Gutiérrez, José María

    2014-03-06

    Snakebite envenoming is a serious public health problem in Central America, where approximately 5,500 cases occur every year. Panama has the highest incidence and El Salvador the lowest. The majority, and most severe, cases are inflicted by the pit viper Bothrops asper (family Viperidae), locally known as 'terciopelo', 'barba amarilla' or 'equis'. About 1% of the bites are caused by coral snakes of the genus Micrurus (family Elapidae). Despite significant and successful efforts in Central America regarding snakebite envenomings in the areas of research, antivenom manufacture and quality control, training of health professionals in the diagnosis and clinical management of bites, and prevention of snakebites, much remains to be done in order to further reduce the impact of this medical condition. This essay presents seven challenges for improving the confrontation of snakebite envenoming in Central America. Overcoming these challenges demands a coordinated partnership of highly diverse stakeholders though inter-sectorial and inter-programmatic interventions.

  1. Rising rates of vaccine exemptions: problems with current policy and more promising remedies.

    PubMed

    Constable, Catherine; Blank, Nina R; Caplan, Arthur L

    2014-04-01

    Parents of school-age children are increasingly claiming nonmedical exemptions to refuse vaccinations required for school entry. The resultant unvaccinated pockets in many areas of the country have been linked with outbreaks of vaccine-preventable diseases. Many states are now focused on reducing rates of nonmedical exemptions by making exemption processes more restrictive or burdensome for the exemptor. These strategies, however, pose ethical problems and may ultimately be inadequate. A shift to strategies that raise the financial liabilities of exemptors may lead to better success and prove ethically more sound. Potential areas of reform include tax law, health insurance, and private school funding programs. We advocate an approach that combines this type of incentive with more effective vaccination education.

  2. On variational formulation of current drive problem in uniformly magnetized relativistic plasma

    NASA Astrophysics Data System (ADS)

    Hu, Y. M.; Hu, Y. J.

    2016-01-01

    A fully relativistic extension of the variational principle with the modified test function for the Spitzer function with momentum conservation in the electron-electron collision is investigated in uniformly magnetized plasma. The term of the momentum conserving constraint in Hirshman’s variational calculation is studied. The model developed is extended for arbitrary temperatures and covers exactly the asymptotic for u\\gg 1 when {{Z}\\text{eff}}\\gg 1 , and the results obtained are suited to facilitate the development of a rigorous variational formulation of current drive efficiency in tokamak plasma.

  3. On the room problem in current hypotheses for the origin of the Gulf of Mexico

    SciTech Connect

    Hall, D.J. )

    1990-09-01

    Although a general consensus exists that the central Gulf of Mexico is underlain by more or less normal oceanic crust, there is considerable disagreement in the literature as to the exact location of the edges of oceanic crust in the Gulf. Yet, it is precisely the exact location of these oceanic crustal edges along both the northern and southern margins of the Gulf that provides the fundamental key to the opening of the Gulf of Mexico, the nature of subsequent rifted margin development, and the original shape of the basin in which thickest Jurassic salt accumulated. A common theme in predrift reconstructions is the problem of too many crustal pieces for the existing space when the major continents are rejoined across the Atlantic. Newly published regional gravity and magnetic maps of the Gulf of Mexico shed considerable light on these issues but have unfortunately been largely ignored. The author argues that no less than four categories of evidence imply this edge effect interpretation is inconsistent and erroneous: There are oceanic crustal edges without edge effects and edge effects without oceanic crustal edges in both the Gulf of Mexico and the western North Atlantic. Once this crucial assumption is abandoned, a simple and symmetrical explanation for the large-scale tectonic evolution of the two main US passive margins can be developed naturally with two major beneficial results: (1) a simple predrift paleoreconstruction for the Gulf of Mexico with no associated room problem and (2) a consistent interpretation of the ECMA and the Gulf Coast Magnetic Anomalies as related to the long sought-after Alleghenian mega-suture. The kinematic development of the East and Gulf Coast continental margins is seen to possess a remarkable fundamental symmetry broken only by subsequent passive margin erosional and sedimentary effects.

  4. Carbon Nanotubes Exposure Risk Assessment: From Toxicology to Epidemiologic Studies (Overview of the Current Problem)

    PubMed Central

    Fatkhutdinova, L. M.; Khaliullin, T. O.; Shvedova, A. A.

    2015-01-01

    Nanoscale size and fiber like structure of carbon nanotubes (CNTs) may determine high reactivity and penetration, as well as the pathogenicity of asbestos and other mineral fibers. Despite many in vitro and in vivo studies, the absence of full-scale data on CNT effects on human health clearly point out the necessity for epidemiological studies. Currently, several projects are initiated worldwide on studying health risks associated with the inhalation of industrial CNTs, including NIOSH-promoted research (United States), the European CANTES study, and the Russian CNT-ERA project. Studies comprising several successive steps, such as CNT exposure assessment in occupational settings, toxicological evaluation, and epidemiological observations, are critical for determining material safety and use criteria. PMID:26457172

  5. [Current problems in the prevention and treatment of infections in patients with cirrhosis].

    PubMed

    Bellot, Pablo; Jara Pérez López, Neftalí; Martínez Moreno, Belén; Such, José

    2010-12-01

    Infections in patients with cirrhosis are a common complication causing substantial morbidity and mortality. Bacterial translocation plays an important role in the pathogenesis of many infections in cirrhosis. In turn, infections are involved in the pathogenesis of many episodes of decompensated cirrhosis, such as esophageal variceal bleeding, renal insufficiency, the hemodynamic alterations of cirrhosis, and hepatic encephalopathy. Spontaneous bacterial peritonitis is currently the most frequent infection in cirrhosis. Mortality from this entity has recently decreased due to early diagnosis, the use of appropriate antibiotic therapy, and albumin administration. However, infections due to multiresistant microorganisms have recently increased, leading to greater mortality. Primary prophylaxis with quinolones is effective in preventing infections and is associated with lower mortality in a selected population of patients with liver cirrhosis.

  6. Chloramphenicol Derivatives as Antibacterial and Anticancer Agents: Historic Problems and Current Solutions

    PubMed Central

    Dinos, George P.; Athanassopoulos, Constantinos M.; Missiri, Dionissia A.; Giannopoulou, Panagiota C.; Vlachogiannis, Ioannis A.; Papadopoulos, Georgios E.; Papaioannou, Dionissios; Kalpaxis, Dimitrios L.

    2016-01-01

    Chloramphenicol (CAM) is the D-threo isomer of a small molecule, consisting of a p-nitrobenzene ring connected to a dichloroacetyl tail through a 2-amino-1,3-propanediol moiety. CAM displays a broad-spectrum bacteriostatic activity by specifically inhibiting the bacterial protein synthesis. In certain but important cases, it also exhibits bactericidal activity, namely against the three most common causes of meningitis, Haemophilus influenzae, Streptococcus pneumoniae and Neisseria meningitidis. Resistance to CAM has been frequently reported and ascribed to a variety of mechanisms. However, the most important concerns that limit its clinical utility relate to side effects such as neurotoxicity and hematologic disorders. In this review, we present previous and current efforts to synthesize CAM derivatives with improved pharmacological properties. In addition, we highlight potentially broader roles of these derivatives in investigating the plasticity of the ribosomal catalytic center, the main target of CAM. PMID:27271676

  7. Current challenges for confronting the public health problem of snakebite envenoming in Central America

    PubMed Central

    2014-01-01

    Snakebite envenoming is a serious public health problem in Central America, where approximately 5,500 cases occur every year. Panama has the highest incidence and El Salvador the lowest. The majority, and most severe, cases are inflicted by the pit viper Bothrops asper (family Viperidae), locally known as ‘terciopelo’, ‘barba amarilla’ or ‘equis’. About 1% of the bites are caused by coral snakes of the genus Micrurus (family Elapidae). Despite significant and successful efforts in Central America regarding snakebite envenomings in the areas of research, antivenom manufacture and quality control, training of health professionals in the diagnosis and clinical management of bites, and prevention of snakebites, much remains to be done in order to further reduce the impact of this medical condition. This essay presents seven challenges for improving the confrontation of snakebite envenoming in Central America. Overcoming these challenges demands a coordinated partnership of highly diverse stakeholders though inter-sectorial and inter-programmatic interventions. PMID:24602234

  8. Obesity, More than a 'Cosmetic' Problem. Current Knowledge and Future Prospects of Human Obesity Genetics.

    PubMed

    Shabana; Hasnain, Shahida

    2016-02-01

    Obesity has been designated as a global epidemic by WHO as its prevalence has increased at an alarming rate in the last few decades worldwide. It is a risk factor for diabetes, hypertension, cardiovascular problems, etc. The contribution of genes to the development of obesity was confirmed in late twentieth century. The concept of monogenic obesity came with the identification of leptin, and mutations in its gene, followed by the discovery of more single gene mutations. However, the recent explosion of obesity could not be explained on the basis of these rare mutations and it was after the first genome-wide association study in 2007 that made possible the identification of different effect size variants in many candidate and non-candidate genes acting in a quantitative way to add to body weight. These studies laid down the basis for polygenic cause of common forms of obesity. The role of epigenetic regulation in the modulation of energy regulation pathway was another important explanation put forward in the latter half of the past decade. Taking into account the quantitative contribution of different variants has given the concept of obesity risk scoring in order to score individuals into different risk groups so as to decide for treatment options.

  9. Non-insulin antidiabetic therapy in cardiac patients: current problems and future prospects.

    PubMed

    Fisman, Enrique Z; Motro, Michael; Tenenbaum, Alexander

    2008-01-01

    Five types of oral antihyperglycemic drugs are currently approved for the treatment of diabetes: biguanides, sulfonylureas, meglitinides, glitazones and alpha-glucosidase inhibitors. We briefly review the cardiovascular effects of the most commonly used antidiabetic drugs in these groups in an attempt to improve knowledge and awareness regarding their influences and potential risks when treating patients with coronary artery disease (CAD). Regarding biguanides, gastrointestinal disturbances such as diarrhea are frequent, and the intestinal absorption of group B vitamins and folate is impaired during chronic therapy. This deficiency may lead to increased plasma homocysteine levels which, in turn, accelerate the progression of vascular disease due to adverse effects on platelets, clotting factors, and endothelium. The existence of a graded association between homocysteine levels and overall mortality in patients with CAD is well established. In addition, metformin may lead to lethal lactic acidosis, especially in patients with clinical conditions that predispose to this complication, such as heart failure or recent myocardial infarction. Sulfonylureas avoid ischemic preconditioning. During myocardial ischemia, they may prevent opening of the ATP-dependent potassium channels, impeding the necessary hyperpolarization that protects the cell by blocking calcium influx. Meglitinides may exert similar effects due to their analogous mechanism of action. During treatment with glitazones, edema has been reported in 5% of patients, and these drugs are contraindicated in diabetics with NYHA class III or IV cardiac status. The long-term effects of alpha-glucosidase inhibitors on morbidity and mortality rates and on diabetic micro- and macrovascular complications is still unknown. Combined sulfonylurea/metformin therapy reveals additive effects on mortality. Four points should be mentioned: (1) the five oral antidiabetic drug groups present proven or potential cardiac hazards; (2

  10. Current problems and future directions of transfusion-induced alloimmunization: summary of an NHLBI working group.

    PubMed

    Zimring, James C; Welniak, Lis; Semple, John W; Ness, Paul M; Slichter, Sherrill J; Spitalnik, Steven L

    2011-02-01

    In April 2010, a working group sponsored by the National Heart, Lung, and Blood Institute was assembled to identify research strategies to improve our understanding of alloimmunization caused by the transfusion of allogeneic blood components and to evaluate potential approaches to both reduce its occurrence and manage its effects. Significant sequelae of alloimmunization were discussed and identified, including difficulties in maintaining chronic transfusion of red blood cells and platelets, hemolytic disease of the newborn, neonatal alloimmune thrombocytopenia, and rejection of transplanted cells and tissues. The discussions resulted in a consensus that identified key areas of future research and developmental areas, including genetic and epigenetic recipient factors that regulate alloimmunization, biochemical specifics of transfused products that affect alloimmunization, and novel technologies for high-throughput genotyping to facilitate extensive and efficient antigen matching between donor and recipient. Additional areas of importance included analysis of unappreciated medical sequelae of alloimmunization, such as cellular immunity and its effect upon transplant and autoimmunity. In addition, support for research infrastructure was discussed, with an emphasis on encouraging collaboration and synergy of animal models biology and human clinical research. Finally, training future investigators was identified as an area of importance. In aggregate, this communication provides a synopsis of the opinions of the working group on the above issues and presents both a list of suggested priorities and the rationale for the topics of focus. The areas of research identified in this report represent potential fertile ground for the medical advancement of preventing and managing alloimmunization in its different forms and mitigating the clinical problems it presents to multiple patient populations. PMID:21251006

  11. Gold deposits in metamorphic belts: Overview of current understanding, outstanding problems, future research, and exploration significance

    USGS Publications Warehouse

    Groves, D.I.; Goldfarb, R.J.; Robert, F.; Hart, C.J.R.

    2003-01-01

    Metamorphic belts are complex regions where accretion or collision has added to, or thickened, continental crust. Gold-rich deposits can be formed at all stages of orogen evolution, so that evolving metamorphic belts contain diverse gold deposit types that may be juxtaposed or overprint each other. This partly explains the high level of controversy on the origin of some deposit types, particularly those formed or overprinted/remobilized during the major compressional orogeny that shaped the final geometry of the hosting metamorphic belts. These include gold-dominated orogenic and intrusion-related deposits, but also particularly controversial gold deposits with atypical metal associations. There are a number of outstanding problems for all types of gold deposits in metamorphc belts. These include the following: (1) definitive classifications, (2) unequivocal recognition of fluid and metal sources, (3) understanding of fluid migration and focusing at all scales, (4) resolution of the precise role of granitoid magmatism, (5) precise gold-depositional mechanisms, particularly those producing high gold grades, and (6) understanding of the release of CO2-rich fluids from subducting slabs and subcreted oceanic crust and granitoid magmas at different crustal levels. Research needs to be better coordinated and more integrated, such that detailed fluid-inclusion, trace-element, and isotopic studies of both gold deposits and potential source rocks, using cutting-edge technology, are embedded in a firm geological framework at terrane to deposit scales. Ultimately, four-dimensional models need to be developed, involving high-quality, three-dimensional geological data combined with integrated chemical and fluid-flow modeling, to understand the total history of the hydrothermal systems involved. Such research, particularly that which can predict superior targets visible in data sets available to exploration companies before discovery, has obvious spin-offs for global- to deposit

  12. Current Progress in Tissue Engineering of Heart Valves: Multiscale Problems, Multiscale Solutions

    PubMed Central

    Cheung, Daniel Y; Duan, Bin; Butcher, Jonathan T.

    2016-01-01

    Introduction Heart valve disease is an increasingly prevalent and clinically serious condition. There are no clinically effective biological diagnostics or treatment strategies. The only recourse available is replacement with a prosthetic valve, but the inability of these devices to grow or respond biologically to their environments necessitates multiple resizing surgeries and life-long coagulation treatment, especially in children. Tissue engineering has a unique opportunity to impact heart valve disease by providing a living valve conduit, capable of growth and biological integration. Areas covered This review will cover current tissue engineering strategies in fabricating heart valves and their progress towards the clinic, including molded scaffolds using naturally-derived or synthetic polymers, decellularization, electrospinning, 3D bioprinting, hybrid techniques, and in vivo engineering. Expert opinion While much progress has been made to create functional living heart valves, a clinically viable product is not yet realized. The next leap in engineered living heart valves will require a deeper understanding of how the natural multi-scale structural and biological heterogeneity of the tissue ensures its efficient function. Related, improved fabrication strategies must be developed that can replicate this de novo complexity, which is likely instructive for appropriate cell differentiation and remodeling whether seeded with autologous stem cells in vitro or endogenously recruited cells. PMID:26027436

  13. Current problems in treating tuberculosis in Italian HIV-infected patients.

    PubMed

    Monno, L; Angarano, G; Carbonara, S; Infante, G; Coppola, S; Costa, D; Quarto, M; Pastore, G

    1993-08-01

    31 Italian HIV-infected patients with newly diagnosed tuberculosis (TB) were reviewed to verify the effectiveness of the most common antituberculosis drugs. The patients were mostly intravenous drug addicts (90%), and 14 (45%) had recently been in prison. 5 patients (16%) had pulmonary TB, 15 (48%) had both pulmonary and extrapulmonary involvement, and 11 (30%) had extrapulmonary disease alone. 6 patients received the association of HRZ, and a 4-drug association including ethambutol was given to an additional 7 patients. The remaining 18 patients were administered the association of HRE. Response to therapy was good in 13 patients (42%), and lacking or delayed in 18 patients (58%). Treatment failure was partly related to the increased occurrence in our area of Mycobacterium tuberculosis strains resistant to the first-line anti-tuberculosis drugs. These observations, along with the need of a faster response to therapy than that currently obtained for TB in AIDS and in view of epidemiological effects, should prompt the definition of alternative therapeutic and prophylactic regimens. PMID:8219181

  14. Current problems in communication from the weather forecast in the prevention of hydraulic and hydrogeological risk

    NASA Astrophysics Data System (ADS)

    Fazzini, Massimiliano; Vaccaro, Carmela

    2014-05-01

    The Italian territory is one of the most fragile hydraulic and hydro geologic of the world, due to its complexity physiographic, lithological and above meteo-climatic too. Moreover, In recent years, the unhappy urbanization, the abandonment of mountain areas and countryside have fostered hydro geological instability, ever more devastating, in relation to the extremes of meteorological events. After the dramatic floods and landscapes of the last 24 months - in which more than 50 people died - it is actually open a public debate on the issues related to prevention, forecasting and management of hydro-meteorological risk. Aim of the correct weather forecasting at different spatial and temporal scales is to avoid or minimize the potential occurrence of damage or human losses resulting from the increasingly of frequent extreme weather events. In Italy, there are two major complex problems that do not allow for effective dissemination of the correct weather forecasting. First, the absence of a national meteorological service - which can ensure the quality of information. In this regard, it is at an advanced stage the establishment of a unified national weather service - formed by technicians to national and regional civil protection and the Meteorological Service of the Air Force, which will ensure the quality of the prediction, especially through exclusive processing of national and local weather forecasting and hydro geological weather alert. At present, however, this lack favors the increasing diffusion of meteorological sites more or less professional - often totally not "ethical" - which, at different spatial scales, tend to amplify the signals from the weather prediction models, describing them the users of the web such as exceptional or rare phenomena and often causing unjustified alarmism. This behavior is almost always aimed at the desire of give a forecast before other sites and therefore looking for new commercial sponsors, with easy profits. On the other hand

  15. Case studies: Application of SEA in provincial level expressway infrastructure network planning in China - Current existing problems

    SciTech Connect

    Zhou Kaiyi; Sheate, William R.

    2011-11-15

    Since the Law of the People's Republic of China on Environmental Impact Assessment was enacted in 2003 and Huanfa 2004 No. 98 was released in 2004, Strategic Environmental Assessment (SEA) has been officially being implemented in the expressway infrastructure planning field in China. Through scrutinizing two SEA application cases of China's provincial level expressway infrastructure (PLEI) network plans, it is found that current SEA practice in expressway infrastructure planning field has a number of problems including: SEA practitioners do not fully understand the objective of SEA; its potential contributions to strategic planning and decision-making is extremely limited; the employed application procedure and prediction and assessment techniques are too simple to bring objective, unbiased and scientific results; and no alternative options are considered. All these problems directly lead to poor quality SEA and consequently weaken SEA's effectiveness.

  16. Platelet-rich plasma therapy for knee joint problems: review of the literature, current practice and legal perspectives in Korea.

    PubMed

    Park, Yong-Geun; Han, Seung Beom; Song, Sang Jun; Kim, Tae Jin; Ha, Chul-Won

    2012-06-01

    Platelet-rich plasma (PRP) is a concentrate extract of platelets from autologous blood, and represents a possible treatment option for the stimulation and acceleration of soft-tissue healing and regeneration in orthopedics. Currently, the availability of devices for outpatient preparation and delivery contributes to the increase in the clinical use of PRP therapy in practical setting of orthopedic fields. However, there is still paucity of scientific evidence in the literature to prove efficacy of PRP therapy for the treatment of ligament or tendon problems around the knee joint. Moreover, strong evidence from well-designed clinical trials to support the PRP therapy for osteoarthritis of the knee joint is yet scanty in the literature. Scientific studies need to be performed to assess clinical indications, efficacy, and safety of PRP, and this will require high powered randomized controlled trials. Nonetheless, some hospitals exaggeratedly advertise PRP procedures as the ultimate treatment and a novel technology with abundant scientific evidence for the treatment of knee problems. As a matter of fact, PRP protocols are currently approved only for use in clinical trials and research, and are not allowed for treatment purpose by any institutions in Korea. At present, clinical use of PRP therapy for ligament or tendon problems or osteoarthritis of knee joint is defined as illegal medical practice, regardless of whether it is performed as a sole procedure or as a part of prolotherapy, because the safety and validity are not yet approved by the Ministry of Health and Welfare and Health Insurance Review and Assessment Service. Practicing physicians should remember that injection of PRP to patients by imposing medical charge is still illegal as per the current medical law in Korea. PMID:22708106

  17. A general-purpose contact detection algorithm for nonlinear structural analysis codes

    SciTech Connect

    Heinstein, M.W.; Attaway, S.W.; Swegle, J.W.; Mello, F.J.

    1993-05-01

    A new contact detection algorithm has been developed to address difficulties associated with the numerical simulation of contact in nonlinear finite element structural analysis codes. Problems including accurate and efficient detection of contact for self-contacting surfaces, tearing and eroding surfaces, and multi-body impact are addressed. The proposed algorithm is portable between dynamic and quasi-static codes and can efficiently model contact between a variety of finite element types including shells, bricks, beams and particles. The algorithm is composed of (1) a location strategy that uses a global search to decide which slave nodes are in proximity to a master surface and (2) an accurate detailed contact check that uses the projected motions of both master surface and slave node. In this report, currently used contact detection algorithms and their associated difficulties are discussed. Then the proposed algorithm and how it addresses these problems is described. Finally, the capability of the new algorithm is illustrated with several example problems.

  18. On the interpretation of current-voltage curves in ionization chambers using the exact solution of the Thomson problem

    NASA Astrophysics Data System (ADS)

    Ridenti, M. A.; Pascholati, P. R.; Gonçalves, J. A. C.; Bueno, C. C.

    2015-09-01

    The I - ΔV characteristic curve of a well type ionization chamber irradiated with 192Ir sources (0.75 Ci-120 Ci) was fitted using the exact solution of the Thomson problem. The recombination coefficient and saturation current were estimated using this new approach. The saturation current was compared with the results of the conventional method based on Boag-Wilson formula. It was verified that differences larger than 1% between both methods only occurred at activities higher than 55 Ci. We concluded that this new approach is recommended for a more accurate estimate of the saturation current when it is not possible to measure currents satisfying the condition I /Isat > 0.95. From the calibration curve the average value of pairs of carriers created per unit volume was estimated to be equal to η = 8.1 ×10-3cm-3s-1 Bq-1 and from that value it was estimated that ~ 17 pairs were created on average per second for each decay of the source.

  19. History of alcohol or drug problems, current use of alcohol or marijuana, and success in quitting smoking.

    PubMed

    Humfleet, G; Muñoz, R; Sees, K; Reus, V; Hall, S

    1999-01-01

    Previous research suggests higher rates of smoking, and smoking cessation failure, in alcohol- and drug-abusing populations. The present study examined the relationship of alcohol/drug treatment history and current alcohol and marijuana consumption with success in smoking cessation treatment in a smoking clinic population. Participants were 199 smokers; 23% reported a history of alcohol/drug problems, 12.6% reported a history of drug treatment, 78.7% reported alcohol use, and 21.3% reported marijuana use during treatment. Results indicate no significant differences in abstinence rates based on history of alcohol/drug problem or treatment. Differences were found for any current alcohol use but not for marijuana use. Both alcohol use at baseline and any alcohol use during treatment predicted smoking at all follow-up points. Alcohol users had significantly lower quit rates than did participants reporting no use. Neither use of marijuana at baseline nor during treatment predicted outcome. These findings suggest that even low to moderate levels of alcohol consumption during smoking cessation may decrease treatment success. PMID:10189984

  20. Summary of some current and possible future environmental problems related to geology and hydrology at Memphis, Tennessee

    USGS Publications Warehouse

    Parks, William Scott; Lounsbury, Richard W.

    1976-01-01

    This report summarizes information concerning many aspects of the geology and hydrology at Memphis, Tenn. It also outlines some of the current problems related to the local geology and hydrology or ones that may arise as a result of urbanization and industrialization of the area. The city is in the Coastal Plain physiographic province and is underlain at shallow depths by sand, clay, silt, gravel, and lignite. These post-Midway strata (Wilcox and younger) make up geologic units belonging to the uppermost Paleocene, Eocene, and Pliocene ( ) Series of the Tertiary System and to the Pleistocene and Holocene Series of the Quaternary System. Environmental problems of immediate or future concern are associated with six general topics: (1) aggregate resources, (2) foundation materials, (3) earthquake hazards, (4) flood hazards, (5) water resources, and (6) solid waste disposal. Consideration of these topics provide an overall insight into the close interrelation of the problems and the need for coordinated studies of the geology and hydrology at Memphis. (Woodard-USGS)

  1. Electron transfer at the contact between Al electrode and gold nanoparticles of polymer: Nanoparticle resistive switching devices studied by alternating current impedance spectroscopy

    SciTech Connect

    Ouyang, Jianyong

    2013-12-02

    Electron transfer at the contact between an Al electrode and Au nanoparticles of polymer:nanoparticle devices is studied by ac impedance spectroscopy. The devices have a polystyrene layer embedded with Au nanoparticles capped with conjugated 2-naphthalenethiol sandwiched between Al and MoO{sub 3}/Al electrodes, and they exhibit electrode-sensitive resistive switches. The devices in the pristine or high resistance state have high capacitance. The capacitance decreases after the devices switch to a low resistance state by a voltage scan. The change in the capacitance is attributed to the voltage-induced change on the electronic structure of the contact between the Al electrode and Au nanoparticles.

  2. Optimization of the front contact to minimize short-circuit current losses in CdTe thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Kephart, Jason Michael

    With a growing population and rising standard of living, the world is in need of clean sources of energy at low cost in order to meet both economic and environmental needs. Solar energy is an abundant resource which is fundamentally adequate to meet all human energy needs. Photovoltaics are an attractive way to safely convert this energy to electricity with little to no noise, moving parts, water, or arable land. Currently, thin-film photovoltaic modules based on cadmium telluride are a low-cost solution with multiple GW/year commercial production, but have lower conversion efficiency than the dominant technology, crystalline silicon. Increasing the conversion efficiency of these panels through optimization of the electronic and optical structure of the cell can further lower the cost of these modules. The front contact of the CdTe thin-film solar cell is critical to device efficiency for three important reasons: it must transmit light to the CdTe absorber to be collected, it must form a reasonably passive interface and serve as a growth template for the CdTe, and it must allow electrons to be extracted from the CdTe. The current standard window layer material, cadmium sulfide, has a low bandgap of 2.4 eV which can block over 20% of available light from being converted to mobile charge carriers. Reducing the thickness of this layer or replacing it with a higher-bandgap material can provide a commensurate increase in device efficiency. When the CdS window is made thinner, a degradation in electronic quality of the device is observed with a reduction in open-circuit voltage and fill factor. One commonly used method to enable a thinner optimum CdS thickness is a high-resistance transparent (HRT) layer between the transparent conducting oxide electrode and window layer. The function of this layer has not been fully explained in the literature, and existing hypotheses center on the existence of pinholes in the window layer which are not consistent with observed results

  3. A QR accelerated volume-to-surface boundary condition for finite element solution of eddy current problems

    SciTech Connect

    White, D; Fasenfest, B; Rieben, R; Stowell, M

    2006-09-08

    We are concerned with the solution of time-dependent electromagnetic eddy current problems using a finite element formulation on three-dimensional unstructured meshes. We allow for multiple conducting regions, and our goal is to develop an efficient computational method that does not require a computational mesh of the air/vacuum regions. This requires a sophisticated global boundary condition specifying the total fields on the conductor boundaries. We propose a Biot-Savart law based volume-to-surface boundary condition to meet this requirement. This Biot-Savart approach is demonstrated to be very accurate. In addition, this approach can be accelerated via a low-rank QR approximation of the discretized Biot-Savart law.

  4. Implied-Consent Laws: A Review of the Literature and Examination of Current Problems and Related Statutes

    PubMed Central

    Voas, Robert B.; Kelley-Baker, Tara; Romano, Eduardo; Vishnuvajjala, Radha

    2009-01-01

    Problem A substantial proportion of drivers arrested for DUI refuse the BAC test, thereby reducing the likelihood that they will be convicted and potentially increasing the number of highrisk multiple offenders contributing to alcohol-related crashes. Method This paper reviews the information on the current status of implied-consent laws (which impose a sanction on offenders who refuse the BAC test) in the 50 states and the other relevant traffic safety laws and policies that may influenced state refusal rates. Results Although there appears to be only a weak relationship between state refusal rates and crash rates, there is strong evidence that BAC test refusals significantly compromise the arrest, prosecution, and sentencing of DUI suspects and the overall enforcement of DUI laws in the United States. Discussion Laws and policies that may reduce the number of refusals are discussed. Impact on industry Alcohol-related crash injuries are an important cost problem for U.S. industry, because of property damage from crashes, crash injuries to employees that raise health costs, or through the reduction of time on the job resulting from a highway injury. PMID:19433199

  5. Military veterans with mental health problems: a protocol for a systematic review to identify whether they have an additional risk of contact with criminal justice systems compared with other veterans groups

    PubMed Central

    2012-01-01

    Background There is concern that some veterans of armed forces, in particular those with mental health, drug or alcohol problems, experience difficulty returning to a civilian way of life and may subsequently come into contact with criminal justice services and imprisonment. The aim of this review is to examine whether military veterans with mental health problems, including substance use, have an additional risk of contact with criminal justice systems when compared with veterans who do not have such problems. The review will also seek to identify veterans’ views and experiences on their contact with criminal justice services, what contributed to or influenced their contact and whether there are any differences, including international and temporal, in incidence, contact type, veteran type, their presenting health needs and reported experiences. Methods/design In this review we will adopt a methodological model similar to that previously used by other researchers when reviewing intervention studies. The model, which we will use as a framework for conducting a review of observational and qualitative studies, consists of two parallel synthesis stages within the review process; one for quantitative research and the other for qualitative research. The third stage involves a cross study synthesis, enabling a deeper understanding of the results of the quantitative synthesis. A range of electronic databases, including MEDLINE, PsychINFO, CINAHL, will be systematically searched, from 1939 to present day, using a broad range of search terms that cover four key concepts: mental health, military veterans, substance misuse, and criminal justice. Studies will be screened against topic specific inclusion/exclusion criteria and then against a smaller subset of design specific inclusion/exclusion criteria. Data will be extracted for those studies that meet the inclusion criteria, and all eligible studies will be critically appraised. Included studies, both quantitative and

  6. EDITORIAL: Close contact Close contact

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2010-07-01

    means to produce nanoscale device elements, such as carbon nanotube transistors [5] and high-density memory crossbar circuits [6]. Recently, the use of scanning tunnelling microscopes has broached a new field of research, which is currently attracting enormous interest—single molecule detection. In issue 25 of Nanotechnology researchers in Houston reported unprecedented sensitivities using localized surface plasmon resonance shifts of gold bipyramids to detect concentrations of substances down to the single molecule level [7]. In issue 26 a collaboration of researchers from the US and Czech Republic describe a different approach, namely tunnelling recognition. In their topical review they describe hydrogen-bond mediated tunnelling and the associated experimental methods that facilitate the detection of single molecules in a tunnel junction using chemically functionalized electrodes [8]. The nanoworld depicted by scanning probe microgaphs over 20 years ago may have looked as extraterrestrial as any science fiction generated alien terrain, but though study and analysis these nano-landscapes have become significantly less alien territory. The work so far to unveil the intricacies of electronic contact has been a story of progress in investigating this new territory and manipulating the mechanisms that govern it to formulate new devices and delve deeper into phenomena at the nanoscale. References [1] Binning G, Rohrer H, Gerber Ch and Weibel E 1982 Phys. Rev. Lett. 49 57-61 [2] X D Cui, X Zarate, J Tomfohr, O F Sankey, A Primak, A L Moore, T A Moore, D Gust, G~Harris and S M Lindsay 2002 Nanotechnology 13 5-14 [3] Martin C A, van Ruitenbeek J M and van der Zant S J H 2010 Nanotechnology 21 265201 [4] Davis J J and Hanyu Y 2010 Nanotechnology 21 265302 [5] Tans S J, Verschueren A R M and Dekker C 1998 Nature 393 49-52 [6] Chen Y, Jung G-Y, Ohlberg D A A, Li X, Stewart D R, Jeppesen J O, Nielsen K A, Stoddart J F and Williams R S 2003 Nanotechnology 14 462-8 [7] Mayer K M

  7. Using the Sherman Morrison Woodbury formula for coupling external circuits with FEM for Simulation of eddy current problems

    SciTech Connect

    White, D

    2009-04-30

    Simulation of three-dimensional transient eddy current problems is important to numerous applications. The Finite Element Method (FEM) has proven be to be powerful numerical technique for solving the Partial Differential Equations (PDE) describing eddy currents. In order to solve the PDE, boundary conditions must be provided, and in many applications the boundary conditions are not known explicitly but can be provided by a Resistor-Inductor-Capacitor (RLC) circuit model. The emphasis of this paper is on an efficient and exact coupling of the RLC network equations with the FEM equations. The coupling is based on an exact linear algebra identity known as the Sherman-Morrison-Woodbury (SMW) formula. One advantage of this approach is that the FEM matrices are not modified. This is important if a fast 'black-box' solver is available for the FEM matrices, these solvers typically require that the matrices have certain mathematical properties and these properties are not modified by the SMW approach. A second advantage is that the SMW approach is valid for an arbitrary number of independent external circuits.

  8. Contact sensing from force measurements

    NASA Technical Reports Server (NTRS)

    Bicchi, Antonio; Salisbury, J. K.; Brock, David L.

    1993-01-01

    This article addresses contact sensing (i.e., the problem of resolving the location of a contact, the force at the interface, and the moment about the contact normals). Called 'intrinsic' contact sensing for the use of internal force and torque measurements, this method allows for practical devices that provide simple, relevant contact information in practical robotic applications. Such sensors have been used in conjunction with robot hands to identify objects, determine surface friction, detect slip, augment grasp stability, measure object mass, probe surfaces, and control collision and for a variety of other useful tasks. This article describes the theoretical basis for their operation and provides a framework for future device design.

  9. Multigrid contact detection method

    NASA Astrophysics Data System (ADS)

    He, Kejing; Dong, Shoubin; Zhou, Zhaoyao

    2007-03-01

    Contact detection is a general problem of many physical simulations. This work presents a O(N) multigrid method for general contact detection problems (MGCD). The multigrid idea is integrated with contact detection problems. Both the time complexity and memory consumption of the MGCD are O(N) . Unlike other methods, whose efficiencies are influenced strongly by the object size distribution, the performance of MGCD is insensitive to the object size distribution. We compare the MGCD with the no binary search (NBS) method and the multilevel boxing method in three dimensions for both time complexity and memory consumption. For objects with similar size, the MGCD is as good as the NBS method, both of which outperform the multilevel boxing method regarding memory consumption. For objects with diverse size, the MGCD outperform both the NBS method and the multilevel boxing method. We use the MGCD to solve the contact detection problem for a granular simulation system based on the discrete element method. From this granular simulation, we get the density property of monosize packing and binary packing with size ratio equal to 10. The packing density for monosize particles is 0.636. For binary packing with size ratio equal to 10, when the number of small particles is 300 times as the number of big particles, the maximal packing density 0.824 is achieved.

  10. Determination of the Actual Contact Surface of a Brush Contact

    NASA Technical Reports Server (NTRS)

    Holm, Ragnar

    1944-01-01

    The number of partial contact surfaces of a brush-ring contact is measured by means of a statistical method. The particular brush is fitted with wicks - that is, insulated and cemented cylinders of brush material, terminating in the brush surface. The number of partial contact surfaces can be computed from the length of the rest periods in which such wicks remain without current. Resistance measurements enable the determination of the size of the contact surfaces. The pressure in the actual contact surface of a recently bedded brush is found to be not much lower than the Brinell hardness of the brush.

  11. Contact hysteroscopy.

    PubMed

    Baggish, M S; Barbot, J

    1983-06-01

    In 1907 innovations in optics and illumination made by Maximilian Nitze were applied to hysteroscopy by Charles David, who wrote a treatise of hysteroscopy. David improved illumination by placing an electric incandescent bulb at the intrauterine end of his endoscope and also sealed the distal end of the tube with a piece of glass. The history of the contact endoscope that the authors personally used is connected to the invention by Vulmiere (1952) of a revolutionary illumination process in endoscopy--the "cold light" process. The components of cold light consist of a powerful external light source that is transmitted via a special optical guide into the endometrial cavity. The 1st application of his principle (1963) was an optical trochar contained in a metallic sheath. This simple endoscope was perfected, and in 1973 Barbot and Parent, in France, began to use it to examine the uterine cavity. Discussion focuses on methods, instrumentation, method for examination (grasping the instrument, setup, light source, anesthesia, dilatation, technique, and normal endometrium); cervical neoplasia; nonneoplastic lesions of the endometrium (endometrial polyp, submucous myoma, endometrial hyperplasia); intrauterine device localization; neoplastic lesions of the endometrium; precursors (adenocarcinoma); hysteroscopy in pregnancy (embryoscopy, hydatidiform mole, postpartum hemorrhage, incomplete abortion, spontaneous abortion, induced abortions, and amnioscopy); and examinations of children and infants. The contact endoscope must make light contact with the structure to be viewed. The principles of contact endoscopy depend on an interpretation of color, contour, vascular pattern, and a sense of touch. These are computed together and a diagnosis is made on the basis of previously learned clinical pathologic correlations. The contact endoscope is composed of 3 parts: an optical guide; a cylindric chamber that collects and traps ambient light; and a magnifying eyepiece. The phase of

  12. [Contact allergies in musicians].

    PubMed

    Gasenzer, E R; Neugebauer, E A M

    2012-12-01

    During the last years, the problem of allergic diseases has increased. Allergies are errant immune responses to a normally harmless substance. In musicians the allergic contact dermatitis to exotic woods is a special problem. Exotic rosewood contains new flavonoids, which trigger an allergic reaction after permanent contact with the instrument. High quality woodwind instruments such as baroque flute or clarinets are made in ebony or palisander because of its great sound. Today instruments for non-professional players are also made in these exotic materials and non-professionals may have the risk to develop contact dermatitis, too. Brass-player has the risk of an allergic reaction to the different metals contained in the metal sheets of modern flutes and brass instruments. Specially nickel and brass alloys are used to product flute tubes or brass instruments. Special problem arises in children: patients who are allergic to plants or foods have a high risk to develop contact dermatitis. Parents don't know the materials of low-priced instruments for beginners. Often unknown cheap woods from exotic areas are used. Low-priced brass instruments contain high amount of brass and other cheap metals. Physicians should advice musician-patients or parents about the risks of the different materials and look for the reason of eczema on mouth, face, or hands. PMID:23233303

  13. [Contact allergies in musicians].

    PubMed

    Gasenzer, E R; Neugebauer, E A M

    2012-12-01

    During the last years, the problem of allergic diseases has increased. Allergies are errant immune responses to a normally harmless substance. In musicians the allergic contact dermatitis to exotic woods is a special problem. Exotic rosewood contains new flavonoids, which trigger an allergic reaction after permanent contact with the instrument. High quality woodwind instruments such as baroque flute or clarinets are made in ebony or palisander because of its great sound. Today instruments for non-professional players are also made in these exotic materials and non-professionals may have the risk to develop contact dermatitis, too. Brass-player has the risk of an allergic reaction to the different metals contained in the metal sheets of modern flutes and brass instruments. Specially nickel and brass alloys are used to product flute tubes or brass instruments. Special problem arises in children: patients who are allergic to plants or foods have a high risk to develop contact dermatitis. Parents don't know the materials of low-priced instruments for beginners. Often unknown cheap woods from exotic areas are used. Low-priced brass instruments contain high amount of brass and other cheap metals. Physicians should advice musician-patients or parents about the risks of the different materials and look for the reason of eczema on mouth, face, or hands.

  14. Effects of School-Wide Positive Behavioral Interventions and Supports on Internalizing Problems: Current Evidence and Future Directions

    ERIC Educational Resources Information Center

    McIntosh, Kent; Ty, Sophie V.; Miller, Lynn D.

    2014-01-01

    School-Wide Positive Behavioral Interventions and Supports (SWPBIS) has a large evidence base for preventing and addressing externalizing problem behavior, but there is little research examining its effects on internalizing problems, such as anxiety and depression. Given the prevalence of internalizing problems in today's children and youth,…

  15. The formulation of dynamical contact problems with friction in the case of systems of rigid bodies and general discrete mechanical systems—Painlevé and Kane paradoxes revisited

    NASA Astrophysics Data System (ADS)

    Charles, Alexandre; Ballard, Patrick

    2016-08-01

    The dynamics of mechanical systems with a finite number of degrees of freedom (discrete mechanical systems) is governed by the Lagrange equation which is a second-order differential equation on a Riemannian manifold (the configuration manifold). The handling of perfect (frictionless) unilateral constraints in this framework (that of Lagrange's analytical dynamics) was undertaken by Schatzman and Moreau at the beginning of the 1980s. A mathematically sound and consistent evolution problem was obtained, paving the road for many subsequent theoretical investigations. In this general evolution problem, the only reaction force which is involved is a generalized reaction force, consistently with the virtual power philosophy of Lagrange. Surprisingly, such a general formulation was never derived in the case of frictional unilateral multibody dynamics. Instead, the paradigm of the Coulomb law applying to reaction forces in the real world is generally invoked. So far, this paradigm has only enabled to obtain a consistent evolution problem in only some very few specific examples and to suggest numerical algorithms to produce computational examples (numerical modeling). In particular, it is not clear what is the evolution problem underlying the computational examples. Moreover, some of the few specific cases in which this paradigm enables to write down a precise evolution problem are known to show paradoxes: the Painlevé paradox (indeterminacy) and the Kane paradox (increase in kinetic energy due to friction). In this paper, we follow Lagrange's philosophy and formulate the frictional unilateral multibody dynamics in terms of the generalized reaction force and not in terms of the real-world reaction force. A general evolution problem that governs the dynamics is obtained for the first time. We prove that all the solutions are dissipative; that is, this new formulation is free of Kane paradox. We also prove that some indeterminacy of the Painlevé paradox is fixed in this

  16. Types of Contact Lenses

    MedlinePlus

    ... Consumer Devices Consumer Products Contact Lenses Types of Contact Lenses Share Tweet Linkedin Pin it More sharing ... Orthokeratology (Ortho-K) Decorative (Plano) Contact Lenses Soft Contact Lenses Soft contact lenses are made of soft, ...

  17. Prioritized Contact Transport Stream

    NASA Technical Reports Server (NTRS)

    Hunt, Walter Lee, Jr. (Inventor)

    2015-01-01

    A detection process, contact recognition process, classification process, and identification process are applied to raw sensor data to produce an identified contact record set containing one or more identified contact records. A prioritization process is applied to the identified contact record set to assign a contact priority to each contact record in the identified contact record set. Data are removed from the contact records in the identified contact record set based on the contact priorities assigned to those contact records. A first contact stream is produced from the resulting contact records. The first contact stream is streamed in a contact transport stream. The contact transport stream may include and stream additional contact streams. The contact transport stream may be varied dynamically over time based on parameters such as available bandwidth, contact priority, presence/absence of contacts, system state, and configuration parameters.

  18. Study of effects of uncertainties of comet and asteroid encounter and contact guidance requirements. Part 2: Tumbling problem studies. [development of navigation and guidance techniques for space rendezvous

    NASA Technical Reports Server (NTRS)

    Cochran, J. E., Jr.

    1974-01-01

    The problem of determining the rotational motion of a tumbling celestial body of the asteroid type using spacecraft-acquired data is addressed. The rotational motion of the body is modeled by free-Eulerian motion of a triaxial, rigid body and its translational motion with respect, to a nonrotating, observing spacecraft, which is not thrusting, is assumed to be uniform during the time observations are made. The mathematical details which form the basis for a digital simulation of the motion and observations are presented. Two algorithms for determining the motion from observations for the special case of uniform rotational motion are given.

  19. Protein folding using contact maps.

    PubMed

    Vendruscolo, M; Domany, E

    2000-01-01

    We discuss the problem of representations of protein structure and give the definition of contact maps. We present a method to obtain a three-dimensional polypeptide conformation from a contact map. We also explain how to deal with the case of nonphysical contact maps. We describe a stochastic method to perform dynamics in contact map space. We explain how the motion is restricted to physical regions of the space. First, we introduce the exact free energy of a contact map and discuss two simple approximations to it. Second, we present a method to derive energy parameters based on perception learning. We prove in an extensive number of situations that the pairwise contact approximation both when alone and when supplemented with a hydrophobic term is unsuitable for stabilizing proteins' native states. PMID:10668399

  20. The Anderson Current Loop

    NASA Technical Reports Server (NTRS)

    Anderson, Karl F.

    1994-01-01

    Four-wire-probe concept applied to electrical-resistance transducers. Anderson current loop is excitation-and-signal-conditioning circuit suitable for use with strain gauges, resistance thermometers, and other electrical-resistance transducers mounted in harsh environments. Used as alternative to Wheatstone bridge. Simplifies signal-conditioning problem, enabling precise measurement of small changes in resistance of transducer. Eliminates some uncertainties in Wheatstone-bridge resistance-change measurements in flight research. Current loop configuration makes effects of lead-wire and contact resistances insignificantly small. Also provides output voltage that varies linearly with change in gauge resistance, and does so at double sensitivity of Wheatstone bridge.

  1. Novel method for immunofluorescence staining of mammalian eggs using non-contact alternating-current electric-field mixing of microdroplets

    PubMed Central

    Hiromitsu, Shirasawa; Jin, Kumagai; Emiko, Sato; Katsuya, Kabashima; Yukiyo, Kumazawa; Wataru, Sato; Hiroshi, Miura; Ryuta, Nakamura; Hiroshi, Nanjo; Yoshihiro, Minamiya; Yoichi, Akagami; Yukihiro, Terada

    2015-01-01

    Recently, a new technique was developed for non-catalytically mixing microdroplets. In this method, an alternating-current (AC) electric field is used to promote the antigen–antibody reaction within the microdroplet. Previously, this technique has only been applied to histological examinations of flat structures, such as surgical specimens. In this study, we applied this technique for the first time to immunofluorescence staining of three-dimensional structures, specifically, mammalian eggs. We diluted an antibody against microtubules from 1:1,000 to 1:16,000, and compared the chromatic degree and extent of fading across dilutions. In addition, we varied the frequency of AC electric-field mixing from 5 Hz to 46 Hz and evaluated the effect on microtubule staining. Microtubules were more strongly stained after AC electric-field mixing for only 5 minutes, even when the concentration of primary antibody was 10 times lower than in conventional methods. AC electric-field mixing also alleviated microtubule fading. At all frequencies tested, AC electric-field mixing resulted in stronger microtubule staining than in controls. There was no clear difference in a microtubule staining between frequencies. These results suggest that the novel method could reduce antibody consumption and shorten immunofluorescence staining time. PMID:26477850

  2. Advances in contact algorithms and their application to tires

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Tanner, John A.

    1988-01-01

    Currently used techniques for tire contact analysis are reviewed. Discussion focuses on the different techniques used in modeling frictional forces and the treatment of contact conditions. A status report is presented on a new computational strategy for the modeling and analysis of tires, including the solution of the contact problem. The key elements of the proposed strategy are: (1) use of semianalytic mixed finite elements in which the shell variables are represented by Fourier series in the circumferential direction and piecewise polynomials in the meridional direction; (2) use of perturbed Lagrangian formulation for the determination of the contact area and pressure; and (3) application of multilevel iterative procedures and reduction techniques to generate the response of the tire. Numerical results are presented to demonstrate the effectiveness of a proposed procedure for generating the tire response associated with different Fourier harmonics.

  3. Contact: Releasing the news

    NASA Astrophysics Data System (ADS)

    Pinotti, Roberto

    The problem of mass behavior after man's future contacts with other intelligences in the universe is not only a challenge for social scientists and political leaders all over the world, but also a cultural time bomb as well. In fact, since the impact of CETI (Contact with Extraterrestrial Intelligence) on human civilization, with its different cultures, might cause a serious socio-anthropological shock, a common and predetermined worldwide strategy is necessary in releasing the news after the contact, in order to keep possible manifestations of fear, panic and hysteria under control. An analysis of past studies in this field and of parallel historical situations as analogs suggests a definite "authority crisis" in the public as a direct consequence of an unexpected release of the news, involving a devastating "chain reaction" process (from both the psychological and sociological viewpoints) of anomie and maybe the collapse of today's society. The only way to prevent all this is to prepare the world's public opinion concerning contact before releasing the news, and to develop a long-term strategy through the combined efforts of scientists, political leaders, intelligence agencies and the mass media, in order to create the cultural conditions in which a confrontation with ETI won't affect mankind in a traumatic way. Definite roles and tasks in this multi-level model are suggested.

  4. Analytical solution of the skin effect problem with the displacement current in Maxwell plasma by the source method

    SciTech Connect

    Alabina, Y. F.; Latyshev, A. V.; Yushkanov, A. A.

    2009-04-15

    We found the analytical solution to the problem of the skin effect for Maxwell plasma with the use of the kinetic equation, where the frequency of electron collisions is constant. We use the specular reflection of electrons from the surface as a boundary condition. The behavior of impedance near to a plasma resonance is considered. We consider limiting cases of skin effect.

  5. The relevance of neuropsychiatric symptoms and cognitive problems in new-onset epilepsy - Current knowledge and understanding.

    PubMed

    Pohlmann-Eden, B; Aldenkamp, A; Baker, G A; Brandt, C; Cendes, F; Coras, R; Crocker, C E; Helmstaedter, C; Jones-Gotman, M; Kanner, A M; Mazarati, A; Mula, M; Smith, M L; Omisade, A; Tellez-Zenteno, J; Hermann, B P

    2015-10-01

    Neurobehavioral and cognition problems are highly prevalent in epilepsy, but most research studies to date have not adequately addressed the precise nature of the relationship between these comorbidities and seizures. To address this complex issue and to facilitate collaborative, innovative research in the rising field of neurobehavioral comorbidities and cognition disturbances in new-onset epilepsy, international epilepsy experts met at the 3rd Halifax International Epilepsy Conference & Retreat at White Point, South Shore, Nova Scotia, Canada from September 18 to 20, 2014. This Conference Proceedings provides a summary of the conference proceedings. Specifically, the following topics are discussed: (i) role of comorbidities in epilepsy diagnosis and management, (ii) role of antiepileptic medications in understanding the relationship between epilepsy and neurobehavioral and cognition problems, and (iii) animal data and diagnostic approaches. Evidence to date, though limited, strongly suggests a bidirectional relationship between epilepsy and cognitive and psychiatric comorbidities. In fact, it is likely that seizures and neurobehavioral problems represent different symptoms of a common etiology or network-wide disturbance. As a reflection of this shared network, psychiatric comorbidities and/or cognition problems may actually precede the seizure occurrence and likely get often missed if not screened.

  6. Room temperature spin injection into (110) GaAs quantum wells using Fe/x-AlO{sub x} contacts in the regime of current density comparable to laser oscillation

    SciTech Connect

    Yokota, Nobuhide Aoshima, Yohei; Ikeda, Kazuhiro; Kawaguchi, Hitoshi; Nishizawa, Nozomi; Munekata, Hiro

    2015-10-28

    We investigate the electrical spin injection into (110) GaAs single quantum wells (SQWs) and multiple quantum wells (MQWs) using light-emitting diodes (LEDs) having Fe/crystalline-AlO{sub x} (x-AlO{sub x}) tunnel barrier contacts. A degree of circular polarization (P{sub c}) of 5.0% is obtained for the SQW LED at 4 K with the current density of 1 kA/cm{sup 2} which is comparable to that for the laser oscillation in vertical-cavity surface-emitting lasers (VCSELs). On the basis of electron spin relaxation time and carrier lifetime in the (110) GaAs SQW measured by time-dependent photoluminescence and the value of P{sub c} = 5.0%, the degree of spin polarization of initially injected electrons (P{sub 0}) in the SQW is estimated to be 6.6% at 4 K. By using the MQW LED having a much stronger electroluminescence, a P{sub c} value of 2.6% is obtained at room temperature (RT) with the current density of 1.5 kA/cm{sup 2}. The temperature and current density dependences of P{sub c} are found to be weak in both the SQW and MQW LEDs. The estimated P{sub 0} of 9.3% at RT suggests that the Fe/x-AlO{sub x} contacts can be used for the RT electrical spin injection for spin-controlled VCSELs.

  7. [Current situation, problem analyses and its countermeasure of formulae of traditional Chinese medicine (FTCM) preventing and curing tumor angiogenesis].

    PubMed

    Xi, Shengyan; Wang, Yanhui; Zhao, Yufang; Lu, Dawei; Li, Pengcheng; Zhang, Qian

    2010-05-01

    Malignant tumor is the common disease that threaten severely to people's health. Formulae of traditional Chinese medicine (FTCM), as the major component of traditional drugs, has played more important role on the prevention and cure to tumor. The Folkman's theory that tumorous growth depends on tumor neovascularization has been confirmed so many years, so to inhibit the tumor angiogenesis, is an important path to treat tumor. The research of FTCM to antagonizing tumor angiogenesis in our country has been started more lately. Since it has been reported some FTCMs can inhibit angiogenesis, and it also exists many problems. The article summarized the correlated research of FTCM to antagonize tumor angiogenesis for the past several years, and according this, analyzed, stated and commented to the problems, countermeasures, development and direction of PTCM to antagonize tumor angiogenesis. PMID:20707214

  8. Direct contact heat exchangers for space

    NASA Astrophysics Data System (ADS)

    Taussig, R. T.; Thayer, W. J.; Lo, V. C. H.; Sakins, K. M.; Bruckner, A. P.

    1985-06-01

    Direct contact heat exchanger concepts have been investigated for use in space, including droplet vortex heat exchangers, coflowing droplet heat exchangers, electrostatically driven heat exchangers, and belt and disk heat exchangers. These concepts are characterized by a low heat exchanger mass per unit of heat transferred, low pressure losses, high reliability, and compactness in design. Operation in zero-G poses unique problems for those direct contact heat exchangers which require separation of two fluid media after heat transfer is completed. Other problems include maintenance of good heat transfer coefficients in the absence of buoyant forces, exposure of heat transfer media to vacuum conditions for certain applications, and materials compatibility. A preliminary systems analysis indicates the potential for substantial weight reductions in turbine Brayton cycle space power systems for output powers above several MW(e). Based on the status of current technology and the results of this analysis, recommendations are made for the most attractive applications and the R&D required to ready a direct contact heat exchanger for use in space.

  9. A Socio-Cultural Reframing of Science and Dis/ability in Education: Past Problems, Current Concerns, and Future Possibilities

    ERIC Educational Resources Information Center

    Connor, David J.; Valle, Jan W.

    2015-01-01

    In this article we assert the value of a socio-cultural reframing of science and dis/ability in education. We begin by problematizing current issues in education pertaining to the often-unquestioned concept of dis/ability and the impact that has upon research, theory, practice, and policy. As our topic is broad, we have chosen to focus upon four…

  10. Avoiding eddy-current problems in ultra-low-field MRI with self-shielded polarizing coils

    NASA Astrophysics Data System (ADS)

    Nieminen, Jaakko O.; Vesanen, Panu T.; Zevenhoven, Koos C. J.; Dabek, Juhani; Hassel, Juha; Luomahaara, Juho; Penttilä, Jari S.; Ilmoniemi, Risto J.

    2011-09-01

    In ultra-low-field magnetic resonance imaging (ULF MRI), superconductive sensors are used to detect MRI signals typically in fields on the order of 10-100 μT. Despite the highly sensitive detectors, it is necessary to prepolarize the sample in a stronger magnetic field on the order of 10-100 mT, which has to be switched off rapidly in a few milliseconds before signal acquisition. In addition, external magnetic interference is commonly reduced by situating the ULF-MRI system inside a magnetically shielded room (MSR). With typical dipolar polarizing coil designs, the stray field induces strong eddy currents in the conductive layers of the MSR. These eddy currents cause significant secondary magnetic fields that may distort the spin dynamics of the sample, exceed the dynamic range of the sensors, and prevent simultaneous magnetoencephalography and MRI acquisitions. In this paper, we describe a method to design self-shielded polarizing coils for ULF MRI. The experimental results show that with a simple self-shielded polarizing coil, the magnetic fields caused by the eddy currents are largely reduced. With the presented shielding technique, ULF-MRI devices can utilize stronger and spatially broader polarizing fields than achievable with unshielded polarizing coils.

  11. Implicit Multibody Penalty-BasedDistributed Contact.

    PubMed

    Xu, Hongyi; Zhao, Yili; Barbic, Jernej

    2014-09-01

    The penalty method is a simple and popular approach to resolving contact in computer graphics and robotics. Penalty-based contact, however, suffers from stability problems due to the highly variable and unpredictable net stiffness, and this is particularly pronounced in simulations with time-varying distributed geometrically complex contact. We employ semi-implicit integration, exact analytical contact gradients, symbolic Gaussian elimination and a SVD solver to simulate stable penalty-based frictional contact with large, time-varying contact areas, involving many rigid objects and articulated rigid objects in complex conforming contact and self-contact. We also derive implicit proportional-derivative control forces for real-time control of articulated structures with loops. We present challenging contact scenarios such as screwing a hexbolt into a hole, bowls stacked in perfectly conforming configurations, and manipulating many objects using actively controlled articulated mechanisms in real time. PMID:26357376

  12. Contact Graph Routing

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott C.

    2011-01-01

    Contact Graph Routing (CGR) is a dynamic routing system that computes routes through a time-varying topology of scheduled communication contacts in a network based on the DTN (Delay-Tolerant Networking) architecture. It is designed to enable dynamic selection of data transmission routes in a space network based on DTN. This dynamic responsiveness in route computation should be significantly more effective and less expensive than static routing, increasing total data return while at the same time reducing mission operations cost and risk. The basic strategy of CGR is to take advantage of the fact that, since flight mission communication operations are planned in detail, the communication routes between any pair of bundle agents in a population of nodes that have all been informed of one another's plans can be inferred from those plans rather than discovered via dialogue (which is impractical over long one-way-light-time space links). Messages that convey this planning information are used to construct contact graphs (time-varying models of network connectivity) from which CGR automatically computes efficient routes for bundles. Automatic route selection increases the flexibility and resilience of the space network, simplifying cross-support and reducing mission management costs. Note that there are no routing tables in Contact Graph Routing. The best route for a bundle destined for a given node may routinely be different from the best route for a different bundle destined for the same node, depending on bundle priority, bundle expiration time, and changes in the current lengths of transmission queues for neighboring nodes; routes must be computed individually for each bundle, from the Bundle Protocol agent's current network connectivity model for the bundle s destination node (the contact graph). Clearly this places a premium on optimizing the implementation of the route computation algorithm. The scalability of CGR to very large networks remains a research topic

  13. Contact lens management of keratoconus.

    PubMed

    Downie, Laura E; Lindsay, Richard G

    2015-07-01

    Contact lenses are the primary form of visual correction for patients with keratoconus. Contemporary advances in contact lens designs and materials have significantly expanded the available fitting options for patients with corneal ectasia. Furthermore, imaging technology, such as corneal topography and anterior segment optical coherence tomography, can be applied to both gain insight into corneal microstructural changes and to guide contact lens fitting. This paper provides a comprehensive review of the range of contact lens modalities, including soft lenses, hybrid designs, rigid lenses, piggyback configurations, corneo-scleral, mini-scleral and scleral lenses that are currently available for the optical management of keratoconus. The review also discusses the importance of monitoring for disease progression in patients with keratoconus, in particular children, who tend to undergo more rapid progressive changes, so as to facilitate appropriate modification to contact lens fitting and/or potential referral for corneal collagen cross-linking treatment, as appropriate. PMID:26104589

  14. Languages in Contact: Findings and Problems.

    ERIC Educational Resources Information Center

    Weinreich, Uriel

    A preface by Andre Martinet and a brief discussion of the author's approach to research introduce this descriptive study of bilingualism. Various aspects of interference--lexical, grammatical, and phonic are examined. Major emphasis is focused on the role and influence of socio-cultural setting and psychological factors inherent in bilingualism.…

  15. Contact Zones, Problem Posing and Critical Consciousness

    ERIC Educational Resources Information Center

    Patel, Lisa

    2012-01-01

    In this article, I share the shape and findings of a participatory action research project with newcomer youths on the contours of status in society. This project was nested in a professional internship experience for newcomer youth, and this experience provided the context in which we explored how privilege and status are afforded in American…

  16. Effect of inductors to mitigate the hot-spot problem in parallel-connected superconducting thin-film fault current limiting elements

    NASA Astrophysics Data System (ADS)

    Yamasaki, H.; Furuse, M.; Kaiho, K.

    2015-06-01

    We have been developing superconducting thin-film fault current limiter (FCL) elements, in which high-resistivity Au-Ag alloy shunt layers are used to protect YBa2Cu3O7 (YBCO) thin films deposited on CeO2-buffered sapphire substrates. The high resistance of the thin films enables the element to withstand high electric fields of more than 40 Vpeak cm-1 during the current-limiting period after quenching, thus greatly reducing the amount of YBCO thin film needed and, consequently, the cost of an FCL. We have succeeded in fabricating and testing 500 V/200 A FCL modules using two 20 cm long YBCO films connected in parallel. In the present study, we performed extensive switching experiments on FCL elements, in which two YBCO films are connected in parallel to achieve higher rated currents, and confirmed the previously observed phenomenon that the hot-spot problem causing film damage just after quench initiation becomes more severe when the total critical current of the thin films is higher. We have investigated the origin of this phenomenon and found that a rapid current transfer from the first-quenched film with lower critical current to the other film causes higher current in the secondly-quenched film that sometimes leads to hot spots. It is demonstrated that the serious hot-spot problem can be mitigated by the use of inductors when the high-resistance FCL elements are connected in parallel. Based on these findings we propose an appropriate architecture of a high electric-field superconducting thin-film FCL that can be used in a real power grid.

  17. Study of Contact Resistances in Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Buehler, M. G.; Lambe, J.; Suszko, S. F.

    1985-01-01

    Techniques explored in search for rapid, reliable test. Resistances of aluminum/silicon contacts and methods to measure subjects of NASA report. Study with three tasks undertaken to evaluate nature and reliability of large numbers of semiconductor contacts of type now being fabricated in integrated circuits: Develop yield analysis for series strings of contacts using wafer-level electrical measurements, and identify different types of faults by visual inspection; develop wafer-level tests to evaluate reliability of contact strings; and develop mathematical model for current flow in contacts and examine contact region for evidence of micro-alloying.

  18. Various contact approaches for the finite cell method

    NASA Astrophysics Data System (ADS)

    Konyukhov, Alexander; Lorenz, Christian; Schweizerhof, Karl

    2015-08-01

    The finite cell method (FCM) provides a method for the computation of structures which can be described as a mixture of high-order FEM and a special integration technique. The method is one of the novel computational methods and is highly developed within the last decade. One of the major problems of FCM is the description of boundary conditions inside cells as well as in sub-cells. And a completely open problem is the description of contact. Therefore, the motivation of the current work is to develop a set of computational contact mechanics approaches which will be effective for the finite element cell method. Thus, for the FCM method we are developing and testing hereby focusing on the Hertz problem the following algorithms: direct integration in the cell method, allowing the fastest implementation, but suffering from numerical artifacts such as the "stamp effect"; the most efficient scheme concerning approximation properties the cell-surface-to-analytical-surface contact element designed for contact with rigid bodies leading to cell-wisely contact elements; and finally the discrete-cell-to-cell contact approach based on the finite discrete method. All developed methods are carefully verified with the analytical Hertz solution. The cell subdivisions, the order of the shape functions as well as the selection of the classes for shape functions are investigated for all developed contact approaches. This analysis allows to choose the most robust approach depending on the needs of the user such as correct representation of the stresses, or only satisfaction of geometrical non-penetration conditions.

  19. [Demography and the feudal mode of production: concerning the positions of current historiography toward the problem. Part 1].

    PubMed

    Pastor, R

    1979-01-01

    This article analyzes the current historiographic approaches to the relationship between population and social and economic systems in preindustrial western European societies. The dominant models in recent years have been demographic, using Malthusian concepts to spell out the relationship between demographic evolution and agrarian development. Shortcomings of this approach are indicated. The article summarizes and criticizes the work of W. Abel which had a significant influence on later workers, of Le Roy Ladurie on the relationship between population movement, real salaries, agricultural production, and general movement of prices; and of Guy Bois on the relationship between the mode of production and population. Comparisons to the works of other authors and to the historical experience of different European countries are made. The author concludes that the theoretical approach of Bois is highly useful but that the model he proposes is too closely tied to the socioeconomic context he studied and is insufficiently abstract to explain other feudal socioeconomic structures of Western Europe. Further development of a theoretical model to cover this relationship is needed. PMID:12311859

  20. Field of researches and applications domains for compact and large-scale DPF devices: Current assets, problems and essentials

    NASA Astrophysics Data System (ADS)

    Gribkov, V. A.

    2014-08-01

    Examination of the most important processes taking place in Dense Plasma Focus (DPF) device that lead to the production of very bright flashes of neutrons and X-rays is presented. It is shown that the current abruption (CA) phenomenon accompanied by the plasma-diode formation plays the key role in these events. Issues of matching of different primary loads with plasma inductive storage and subsequently with plasma diode are discussed. It is shown that at the intermediate energies it is possible to attain the perfect matching. Results in some applications of medium-sized DPF obtained recently in radiation material science, dynamic quality control, biology and medicine are presented. It is shown that for better matching at very high energies the classical intermediate energy compressing element can be used. Besides schemes with laser support switching are discussed. Extrapolations of DPF phenomena to very high and very low energies with their feasibility are examined. Envisioned applications of such huge and tiny DPF devices in power production, medicine and electronics are discussed.

  1. A socio-cultural reframing of science and dis/ability in education: past problems, current concerns, and future possibilities

    NASA Astrophysics Data System (ADS)

    Connor, David J.; Valle, Jan W.

    2015-12-01

    In this article we assert the value of a socio-cultural reframing of science and dis/ability in education. We begin by problematizing current issues in education pertaining to the often-unquestioned concept of dis/ability and the impact that has upon research, theory, practice, and policy. As our topic is broad, we have chosen to focus upon four interconnected areas: (1) the historical mistrust of science and pseudo-science by people with dis/abilities; (2) the pervasive use of pseudo-science within the contemporary field of special education; (3) the use of dis/ability studies in education (DSE) to provide a contrast between a traditional positivist framing and a socio-cultural framing of dis/ability, and; (4) a brief exploration of what a DSE/socio-cultural grounding looks like for both schools and classroom teachers. In sum, our intention is to engage science educators to reject deficit-notions of dis/ability in favor of understanding it as part of human variation, and consider the personal and professional benefits of this shift.

  2. How artificial intelligence tools can be used to assess individual patient risk in cardiovascular disease: problems with the current methods

    PubMed Central

    Grossi, Enzo

    2006-01-01

    Background In recent years a number of algorithms for cardiovascular risk assessment has been proposed to the medical community. These algorithms consider a number of variables and express their results as the percentage risk of developing a major fatal or non-fatal cardiovascular event in the following 10 to 20 years Discussion The author has identified three major pitfalls of these algorithms, linked to the limitation of the classical statistical approach in dealing with this kind of non linear and complex information. The pitfalls are the inability to capture the disease complexity, the inability to capture process dynamics, and the wide confidence interval of individual risk assessment. Artificial Intelligence tools can provide potential advantage in trying to overcome these limitations. The theoretical background and some application examples related to artificial neural networks and fuzzy logic have been reviewed and discussed. Summary The use of predictive algorithms to assess individual absolute risk of cardiovascular future events is currently hampered by methodological and mathematical flaws. The use of newer approaches, such as fuzzy logic and artificial neural networks, linked to artificial intelligence, seems to better address both the challenge of increasing complexity resulting from a correlation between predisposing factors, data on the occurrence of cardiovascular events, and the prediction of future events on an individual level. PMID:16672045

  3. [Contact lens-related keratitis].

    PubMed

    Steiber, Zita; Berta, András; Módis, László

    2013-11-10

    Nowadays, keratitis, corneal infection due to wearing contact lens means an increasingly serious problem. Neglected cases may lead to corneal damage that can cause blindness in cases of otherwise healthy eyes. Early diagnosis based on the clinical picture and the typical patient history is an important way of prevention. Prophylaxis is substantial to avoid bacterial and viral infection that is highly essential in this group of diseases. Teaching contact lens wearers the proper contact lens care, storage, sterility, and hygiene regulations is of great importance. In case of corneal inflammation early accurate diagnosis supported by microbiological culture from contact lenses, storage boxes or cornea is very useful. Thereafter, targeted drug therapy or in therapy-resistant cases surgical treatment may even be necessary in order to sustain suitable visual acuity.

  4. Irritant Contact Dermatitis

    MedlinePlus

    ... and rashes clinical tools newsletter | contact Share | Irritant Contact Dermatitis Information for adults A A A This ... severe involvement in the patient's armpit. Overview Irritant contact dermatitis is an inflammatory rash caused by direct ...

  5. Contact Lens Risks

    MedlinePlus

    ... Health and Consumer Devices Consumer Products Contact Lenses Contact Lens Risks Share Tweet Linkedin Pin it More ... redness blurred vision swelling pain Serious Hazards of Contact Lenses Symptoms of eye irritation can indicate a ...

  6. Contact Lens Care

    MedlinePlus

    ... For Consumers Consumer Information by Audience For Women Contact Lens Care Share Tweet Linkedin Pin it More ... 1088, www.fda.gov/medwatch Learn More about Contact Lens Care Other Tips on Contact Lenses Decorative ...

  7. Contact Lens Solution Toxicity

    MedlinePlus

    ... rash and rashes clinical tools newsletter | contact Share | Contact Lens Solution Toxicity Information for adults A A A This image shows a reaction to contact lens solution. The prominent blood vessels and redness ...

  8. Protein Residue Contacts and Prediction Methods

    PubMed Central

    Adhikari, Badri

    2016-01-01

    In the field of computational structural proteomics, contact predictions have shown new prospects of solving the longstanding problem of ab initio protein structure prediction. In the last few years, application of deep learning algorithms and availability of large protein sequence databases, combined with improvement in methods that derive contacts from multiple sequence alignments, have shown a huge increase in the precision of contact prediction. In addition, these predicted contacts have also been used to build three-dimensional models from scratch. In this chapter, we briefly discuss many elements of protein residue–residue contacts and the methods available for prediction, focusing on a state-of-the-art contact prediction tool, DNcon. Illustrating with a case study, we describe how DNcon can be used to make ab initio contact predictions for a given protein sequence and discuss how the predicted contacts may be analyzed and evaluated. PMID:27115648

  9. Measuring the prevalence of current, severe symptoms of mental health problems in a canadian correctional population: implications for delivery of mental health services for inmates.

    PubMed

    Brown, Gregory P; Hirdes, John P; Fries, Brant E

    2015-01-01

    This study measured the prevalence of current, severe symptoms of a mental health problem in an adult population of inmates in Ontario, Canada. The Resident Assessment Instrument-Mental Health was used to measure the prevalence of symptoms among a sample of 522 inmates. Propensity score weighting was used to adjust for nonrandom selection into the sample. Prevalence estimates were derived for the total inmate population, remand and sentenced, males and females, and Aboriginal and non-Aboriginal inmates. It is estimated that 41.1% of Ontario inmates will have at least one current, severe symptom of a mental health problem; of this group, 13.0%, will evidence two or more symptoms. The number of symptoms is strongly associated with presence of a psychiatric diagnosis and level of mental health care needs. Female (35.1%) and Aboriginal (18.7%) inmates are more likely to demonstrate two or more current, severe symptoms. Greater efforts must be made to bridge the gap between correctional and mental health care systems to ensure inmates in correctional facilities can access and receive appropriate mental health care services.

  10. Non-contact ECG monitoring

    NASA Astrophysics Data System (ADS)

    Smirnov, Alexey S.; Erlikh, Vadim V.; Kodkin, Vladimir L.; Keller, Andrei V.; Epishev, Vitaly V.

    2016-03-01

    The research is dedicated to non-contact methods of electrocardiography. The authors describe the routine of experimental procedure and suggest the approach to solving the problems which arise at indirect signal recording. The paper presents the results of experiments conducted by the authors, covers the flow charts of ECG recorders and reviews the drawbacks of filtering methods used in foreign equivalents.

  11. Revisiting mask contact hole measurements

    NASA Astrophysics Data System (ADS)

    Higuchi, Masaru; Gallagher, Emily; Ceperley, Daniel; Brunner, Timothy; Bowley, Reg; McGuire, Anne

    2006-10-01

    Contact holes represent one of the biggest critical dimension (CD) mask metrology challenges for 45nm technology mask development. The challenge is a consequence of both wafer and mask sensitivities. Large mask error factors and the small process windows found when contact holes are imaged on wafers impose very tight mask specifications for CD uniformity. The resultant CD error budget leaves little room for mask metrology. Current advanced mask metrology deploys a CD-SEM to characterize the mask contact hole CD uniformity. Measuring a contact hole is complex since it is inherently two-dimensional and is not always well-characterized by one-dimensional x- and y-axis measurements. This paper will investigate contact metrics such as line edge roughness (LER), region of interest (ROI) size, area, and CD sampling methods. The relative merits of each will be explored. Ultimately, an understanding of the connection between what is physically measured on the mask and what impacts wafer imaging must be understood. Simulations will be presented to explore the printability of a contact hole's physical attributes. The results will be summarized into a discussion of optimal contact hole metrology for 45nm technology node masks.

  12. Finite Element Analysis of 2-D Elastic Contacts Involving FGMs

    NASA Astrophysics Data System (ADS)

    Abhilash, M. N.; Murthy, H.

    2014-05-01

    The response of elastic indenters in contact with Functionally Graded Material (FGM) coated homogeneous elastic half space has been presented in the current paper. Finite element analysis has been used due to its ability to handle complex geometry, material, and boundary conditions. Indenters of different typical surface profiles have been considered and the problem has been idealized as a two-dimensional (2D) plane strain problem considering only normal loads. Initially, indenters were considered to be rigid and the results were validated with the solutions presented in the literature. The analysis has then been extended to the case of elastic indenters on FGM-coated half spaces and the results are discussed.

  13. Non Contact Measuring Machine

    NASA Astrophysics Data System (ADS)

    Carvalho, Fernando D.; Sebastiao, Pedro; Henriques, Bernardo G.

    1989-01-01

    One of the problems of the production of cables is the measurement of the thickness plastic cover at the production line. If for some reason the thickness of the plastic is smaller than the minimum necessary several meters of cable may be lost. If the problem exists in the middle of a long cable and the default is not detected in time, the loss will be significant. To solve this problem it is possible to use automatic measuring machines which may detect a default as soon as it happens. It is also possible to interact with the production line in order to avoid any losses. In this paper it is presented a non contact measuring machine, developed for this purpose. The machine uses a laser which is scanned through a field of 80 mm. The interruption of the beam gives information about the external dimension of the object. The technical study of the resolution, sensitivity and precision are presented on the paper. Also the hardware solution and the software are presented. The machine has an interface which allows communication with a PC. The PC may receive information from several measuring units and to interact with machines installed at the production line. The prototype is finished and is going to be tested in the industry.

  14. Contact Dermatitis in Pediatrics.

    PubMed

    Pelletier, Janice L; Perez, Caroline; Jacob, Sharon E

    2016-08-01

    Contact dermatitis is an umbrella term that describes the skin's reaction to contacted noxious or allergenic substances. The two main categories of contact dermatitis are irritant type and allergic type. This review discusses the signs, symptoms, causes, and complications of contact dermatitis. It addresses the testing, treatment, and prevention of contact dermatitis. Proper management of contact dermatitis includes avoidance measures for susceptible children. Implementation of a nickel directive (regulating the use of nickel in jewelry and other products that come into contact with the skin) could further reduce exposure to the most common allergens in the pediatric population. [Pediatr Ann. 2016;45(8):e287-e292.]. PMID:27517356

  15. Current Titles

    SciTech Connect

    Various

    2006-06-01

    This booklet is published for those interested in current research being conducted at the National Center for Electron Microscopy. The NCEM is a DOE-designated national user facility and is available at no charge to qualified researchers. Access is controlled by an external steering committee. Interested researchers may contact Jane Cavlina, Administrator, at 510/486-6036.

  16. Current problems of nonionizing radiation.

    PubMed

    Izmerov, N F

    1985-06-01

    Electromagnetic radiation in the radiofrequency range is the most common type of nonionizing radiation. The accelerated development in telecommunications and the introduction of power transmission lines, as well as glue drying and plastic heating in the wood and plastic industries, cause both occupational and nonoccupational systematic exposure to electromagnetic radiation in the radiofrequency range. For the hygienic rating of radiowave exposure it is necessary to use biological models to evaluate, in depth, the mechanisms and effects of electromagnetic radiation. The ultra- and superhigh frequency range is the most active in causing biological responses. The high frequency range is less active. Physical characteristics (continuous and impulse) and the combined effect of the electromagnetic field with other factors, eg, elevated air temperature, etc, have an effect on biological responses.

  17. [Current legal problems of sterilization].

    PubMed

    Eser, A; Koch, H G

    1982-06-01

    Voluntary sterilization has not yet acquired comprehensive legal formulation. Thus there is a legal vacuum which physicians have attempted to fill by relying on their internal professional regulations. These provide for sterilization on an indication; however, an offense against this rule is not punishable in the courts. There is a prohibition, in particular, against so-called "courtesy sterilization," but this is of little significance today when so many social indications for sterilization can be found. But in general these professional regulations provide no useful assistance in deciding when a sterilization is permitted. In criminal law sterilization done by free will is not punishable nor is any indication required. The law deals in detail with the meaning and definition of the "free will" of the person being sterilized. This involves: capacity to have a free will, what to do about persons lacking that capacity (especially minors), and necessity to ensure that that woman understands all the consequences of sterilization. The civil courts have much more to do with sterilization than the criminal ones. One ground for suit is that the sterilization was "contrary to accepted morality," although the courts will generally hold that the woman herself cannot assert this claim. Another ground is lack of consent by the woman. Another ground is improper performance by the physician, i.e., malpractice. Thus the physician has to fear most the charges of no valid consent or malpractice. Questions of insurance law are also pertinent, since an insured person can be compensated for sterilization only if the procedure is legal.

  18. Allergic contact dermatitis to white petrolatum.

    PubMed

    Kang, Hee; Choi, Jun; Lee, Ai-Young

    2004-05-01

    White petrolatum is known for its nonsensitizing and nonirritating properties. Only a few cases of allergic contact dermatitis to white petrolatum have been reported. Although it is a rare event, the finding of contact sensitization to white petrolatum raises the potential problem of its usage of common topical agents or vehicles for patch testing. We herein report a case of allergic contact dermatitis to white petrolatum.

  19. Pose and motion from contact

    SciTech Connect

    Jia, Y.B.; Erdmann, M.

    1999-05-01

    In the absence of vision, grasping an object often relies on tactile feedback from the fingertips. As the finger pushes the object, the fingertip can feel the contact point move. If the object is known in advance, from this motion the finger may infer the location of the contact point on the object, and thereby, the object pose. This paper primarily investigates the problem of determining the pose (orientation and position) and motion (velocity and angular velocity) of a planar object with known geometry from such contact motion generated by pushing. A dynamic analysis of pushing yields a nonlinear system that relates through contact the object pose and motion to the finger motion. The contact motion on the fingertip thus encodes certain information about the object pose. Nonlinear observability theory is employed to show that such information is sufficient for the finger to observe not only the pose, but also the motion of the object. Therefore, a sensing strategy can be realized as an observer of the nonlinear dynamic system. Two observers are subsequently introduced. The first observer, based on the work of Gautheir, Hammouri, and Othman (1992), has its gain determined by the solution of a Lyapunov-like equation; it can be activated at any time instant during a push. The second observer, based on Newton`s method, solves for the initial (motionless) object pose from three intermediate contact points during a push. Under the Coulomb-friction model, the paper deals with support friction in the plane and/or contact friction between the finger and the object. Extensive simulations have been done to demonstrate the feasibility of the two observers. Preliminary experiments (with an Adept robot) have also been conducted. A contact sensor has been implemented using strain gauges.

  20. On the structure of contact binaries. I - The contact discontinuity

    NASA Technical Reports Server (NTRS)

    Shu, F. H.; Lubow, S. H.; Anderson, L.

    1976-01-01

    The problem of the interior structure of contact binaries is reviewed, and a simple resolution of the difficulties which plague the theory is suggested. It is proposed that contact binaries contain a contact discontinuity between the lower surface of the common envelope and the Roche lobe of the cooler star. This discontinuity is maintained against thermal diffusion by fluid flow, and the transition layer is thin to the extent that the dynamical time scale is short in comparison with the thermal time scale. The idealization that the transition layer has infinitesimal thickness allows a simple formulation of the structure equations which are closed by appropriate jump conditions across the discontinuity. The further imposition of the standard boundary conditions suffices to define a unique model for the system once the chemical composition, the masses of the two stars, and the orbital separation are specified.

  1. Electrical contact resistance degradation of a hot-switched simulated metal MEMS contact.

    SciTech Connect

    Dugger, Michael Thomas; Dickrell, Daniel John, III

    2005-03-01

    Electrical contact resistance testing was performed by hot-switching a simulated gold-platinum metal microelectromechanical systems contact. The experimental objective was to determine the sensitivity of the contact resistance degradation to current level and environment. The contact resistance increased sharply after 100 hot-switched cycles in air. Hot-switching at a reduced current and in nitrogen atmosphere curtailed contact resistance degradation by several orders of magnitude. The mechanism responsible for the resistance degradation was found to be arc-induced decomposition of adsorbed surface contaminants.

  2. Contact dermatitis from an ostomy deodorant.

    PubMed

    Davids, M G; Hodgson, G A; Evans, E

    1978-02-01

    Two patients with contact dermatitis from an ostomy agent are described. Detailed patch testing revealed contact allergic dermatitis to one of the twelve groups of ingredients which largely comprised citronella oil. The problem of dermatitis is discussed in relation to the perfume ingredients of the ostomy agent.

  3. A survey of wheel-rail contact models for rail vehicles

    NASA Astrophysics Data System (ADS)

    Meymand, Sajjad Z.; Keylin, Alexander; Ahmadian, Mehdi

    2016-03-01

    Accurate and efficient contact models for wheel-rail interaction are essential for the study of the dynamic behaviour of a railway vehicle. Assessment of the contact forces and moments, as well as contact geometry provide a fundamental foundation for such tasks as design of braking and traction control systems, prediction of wheel and rail wear, and evaluation of ride safety and comfort. This paper discusses the evolution and the current state of the theories for solving the wheel-rail contact problem for rolling stock. The well-known theories for modelling both normal contact (Hertzian and non-Hertzian) and tangential contact (Kalker's linear theory, FASTSIM, CONTACT, Polach's theory, etc.) are reviewed. The paper discusses the simplifying assumptions for developing these models and compares their functionality. The experimental studies for evaluation of contact models are also reviewed. This paper concludes with discussing open areas in contact mechanics that require further research for developing better models to represent the wheel-rail interaction.

  4. Johnson-Kendall-Roberts adhesive contact for a toroidal indenter

    NASA Astrophysics Data System (ADS)

    Argatov, Ivan; Li, Qiang; Pohrt, Roman; Popov, Valentin L.

    2016-07-01

    The unilateral axisymmetric frictionless adhesive contact problem for a toroidal indenter and an elastic half-space is considered in the framework of the Johnson-Kendall-Roberts theory. In the case of a semi-fixed annular contact area, when one of the contact radii is fixed, while the other varies during indentation, we obtain the asymptotic solution of the adhesive contact problem based on the solution of the corresponding unilateral non-adhesive contact problem. In particular, the adhesive contact problem for Barber's concave indenter is considered in detail. In the case when both contact radii are variable, we construct the leading-order asymptotic solution for a narrow annular contact area. It is found that for a v-shaped generalized toroidal indenter, the pull-off force is independent of the elastic properties of the indented solid.

  5. Formula Gives Better Contact-Resistance Values

    NASA Technical Reports Server (NTRS)

    Lieneweg, Udo; Hannaman, David J.

    1988-01-01

    Lateral currents in contact strips taken into account. Four-terminal test structures added to intergrated circuits to enable measurement of interfacial resistivities of contacts between thin conducting layers. Thin-film model simplified quasi-two-dimensional potential model that accounts adequately for complicated three-dimensional, nonuniform current densitites. Effects of nonuniformity caused by lateral current flow in strips summarized in equivalent resistance Rs and voltage Vs.

  6. Confinement of spin-orbit induced Dirac states in quantum point contacts

    NASA Astrophysics Data System (ADS)

    Li, Tommy

    2015-08-01

    The quantum transmission problem for a particle moving in a quantum point contact in the presence of a Rashba spin-orbit interaction and applied magnetic field is solved semiclassically. A strong Rashba interaction and parallel magnetic field form emergent Dirac states at the center of the constriction, leading to the appearance of resonances which carry spin current and become bound at high magnetic fields. These states can be controlled in situ by modulation of external electric and magnetic fields, and can be used to turn the channel into a spin pump which operates at zero bias. It is shown that this effect is currently experimentally accessible in p -type quantum point contacts.

  7. Continuum model of tensile fracture of metal melts and its application to a problem of high-current electron irradiation of metals

    SciTech Connect

    Mayer, Alexander E. E-mail: mayer.al.evg@gmail.com; Mayer, Polina N.

    2015-07-21

    A continuum model of the metal melt fracture is formulated on the basis of the continuum mechanics and theory of metastable liquid. A character of temperature and strain rate dependences of the tensile strength that is predicted by the continuum model is verified, and parameters of the model are fitted with the use of the results of the molecular dynamics simulations for ultra-high strain rates (≥1–10/ns). A comparison with experimental data from literature is also presented for Al and Ni melts. Using the continuum model, the dynamic tensile strength of initially uniform melts of Al, Cu, Ni, Fe, Ti, and Pb within a wide range of strain rates (from 1–10/ms to 100/ns) and temperatures (from melting temperature up to 70–80% of critical temperature) is calculated. The model is applied to numerical investigation of a problem of the high-current electron irradiation of Al, Cu, and Fe targets.

  8. Contact reactions to food.

    PubMed

    Killig, Claudia; Werfel, Thomas

    2008-05-01

    Cutaneous adverse reactions to foods, spices, and food additives can occur both in occupational and nonoccupational settings in those who grow, handle, prepare, or cook food. Because spices are also utilized in cosmetics and perfumes, other exposures are encountered that can result in adverse cutaneous reactions. This article describes the reaction patterns that can occur upon contact with foods, including irritant contact dermatitis and allergic contact dermatitis. The ingestion of culprit foods by sensitized individuals can provoke a generalized eczematous rash, referred to as systemic contact dermatitis. Other contact reactions to food include contact urticaria and protein contact dermatitis provoked by high-molecular-weight food proteins often encountered in patients with atopic dermatitis. Phototoxic and photoallergic contact dermatitis are also considered.

  9. Allergic Contact Dermatitis

    MedlinePlus

    ... causes of allergic contact dermatitis include nickel, chromates, rubber chemicals, and topical antibiotic ointments and creams. Frequent ... construction workers who are in contact with cement. Rubber chemicals are found in gloves, balloons, elastic in ...

  10. Glasses and Contact Lenses

    MedlinePlus

    ... Here's Help White House Lunch Recipes Glasses and Contact Lenses KidsHealth > For Kids > Glasses and Contact Lenses Print A A A Text Size What's ... together the way they should. But eyeglasses or contact lenses, also called corrective lenses, can help most ...

  11. CONTACT URTICARIA: PRESENT SCENARIO

    PubMed Central

    Bhatia, Ruchi; Alikhan, Ali; Maibach, Howard I

    2009-01-01

    Immunological contact urticaria is a hypersensitivity reaction that appears on the skin following contact with an eliciting substance. Recent advances in our understanding of the molecular mechanism and pathogenesis of this reaction have altered its classification, diagnosis, and treatment. We discuss classification, epidemiology, diagnosis, testing, and treatment options that are available to patients with contact urticaria. PMID:20161861

  12. Evaluation of Contact Separation Force Testing as a Screening Methodology for Electrical Socket Contacts

    NASA Technical Reports Server (NTRS)

    Green, Chris; Greenwell, Chris; Brusse, jay; Krus, Dennis; Leidecker, Henning

    2009-01-01

    During system level testing intermittent and permanent open circuit failures of mated, crimp removable, electrical contact pairs were experienced. The root cause of the failures was determined to be low (but not zero) contact forces applied by the socket contact tines against the engaging pin. The low contact force reduces the effectiveness of the wiping action of the socket tines against the pin. The observed failure mode may be produced when insufficient wiping during mate, demate and small relative movement in use allows for the accumulation of debris or insulating films that electrically separate the contact pair. The investigation identified at least three manufacturing process control problems associated with the socket contacts that enabled shipment of contacts susceptible to developing low contact forces: (1) Improper heat treatment of the socket tines resulting in plastic rather than elastic behavior; (2) Overly thinned socket tines at their base resulting in reduced pin retention forces; (3) insufficient screening tests to identify parts susceptible to the aforementioned failure mechanisms. The results from an extensive screening program of socket contacts utilizing the industry standard contact separation force test procedures are described herein. The investigation shows this method to be capable of identifying initially weak sockets. However, sockets whose contact retention forces may degrade during use may not be screened out by pin retention testing alone. Further investigations are required to correlate low contact retention forces with increased electrical contact resistance in the presence of insulating films that may accumulate in the use environment.

  13. [Contact lenses permeable to gas. Literature review].

    PubMed

    Livshiys, V S; Popova, T A; Zaikov, G E; Kuś, H

    1989-01-01

    Some medical-technical requirements concerning ophthalmic contact lenses were formulated. A whole series of scientific descriptions of contact lenses was analysed. A short characterization of lenses was given on the basis of PMMA (polymethacrylate of methyl), silicon rubber, poly-2-methacrylic cellulose and cellulose acetate-butyrate; the properties of contact lenses made of materials achieved through a modification of the above-mentioned ones as well as made of new materials were also examined. The problems of transmission of gases of contact lenses were described and the calculations necessary for a minimum of the gas transmittance were mentioned, starting from partial oxygen to the eye cornea. Some ways of solving the problems concerning the insertion of therapeutic substances into contact lenses are described together with prevention of the accumulation of lacrimation fluid protein on their surfaces. PMID:2682577

  14. Complementary Barrier Infrared Detector (CBIRD) Contact Methods

    NASA Technical Reports Server (NTRS)

    Ting, David Z.; Hill, Cory J.; Gunapala, Sarath D.

    2013-01-01

    The performance of the CBIRD detector is enhanced by using new device contacting methods that have been developed. The detector structure features a narrow gap adsorber sandwiched between a pair of complementary, unipolar barriers that are, in turn, surrounded by contact layers. In this innovation, the contact adjacent to the hole barrier is doped n-type, while the contact adjacent to the electron barrier is doped p-type. The contact layers can have wider bandgaps than the adsorber layer, so long as good electrical contacts are made to them. If good electrical contacts are made to either (or both) of the barriers, then one could contact the barrier(s) directly, obviating the need for additional contact layers. Both the left and right contacts can be doped either n-type or ptype. Having an n-type contact layer next to the electron barrier creates a second p-n junction (the first being the one between the hole barrier and the adsorber) over which applied bias could drop. This reduces the voltage drop over the adsorber, thereby reducing dark current generation in the adsorber region.

  15. Contact lens in keratoconus

    PubMed Central

    Rathi, Varsha M; Mandathara, Preeji S; Dumpati, Srikanth

    2013-01-01

    Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP) lenses, soft and soft toric lenses, piggy back contact lenses (PBCL), hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the English language with the keywords keratoconus and various contact lenses such as Rose k lens, RGP lens, hybrid lens, scleral lens and PBCL. PMID:23925325

  16. Multi-point contact of the high-speed vehicle-turnout system dynamics

    NASA Astrophysics Data System (ADS)

    Ren, Zunsong

    2013-05-01

    The wheel-rail contact problems, such as the number, location and the track of contact patches, are very important for optimizing the spatial structure of the rails and lowering the vehicle-turnout system dynamics. However, the above problems are not well solved currently because of having the difficulties in how to determine the multi-contact, to preciously present the changeable profiles of the rails and to establish an accurate spatial turnout system dynamics model. Based on a high-speed vehicle-turnout coupled model in which the track is modeled as flexible with rails and sleepers represented by beams, the line tracing extreme point method is introduced to investigate the wheel-rail multiple contact conditions and the key sections of the blade rail, longer nose rail, shorter rail in the switch and nose rail area are discretized to represent the varying profiles of rails in the turnout. The dynamic interaction between the vehicle and turnout is simulated for cases of the vehicle divergently passing the turnout and the multi-point contact is obtained. The tracks of the contact patches on the top of the rails are presented and the wheel-rail impact forces are offered in comparison with the contact patches transference on the rails. The numerical simulation results indicate that the length of two-point contact occurrence of a worn wheel profile and rails is longer than that of the new wheel profile and rails; The two-point contact definitely occurs in the switch and crossing area. Generally, three-point contact doesn't occur for the new rail profile, which is testified by the wheel-rails interpolation distance and the first order derivative function of the tracing line extreme points. The presented research is not only helpful to optimize the structure of the turnout, but also useful to lower the dynamics of the high speed vehicle-turnout system.

  17. Non-contact measurement of contact wire

    NASA Astrophysics Data System (ADS)

    Yi, Yaxing; Ye, Xuemei; Li, Zhongke; Yue, Kaiduan

    2008-12-01

    The overhead contact system is the power supply unit of the electric locomotive. This article is to introduce our newly developed method to measure the height and pull out value of the contact wire. A carema dolly which can move on railway is applied to bear the weight of the measure equipment; two linear CCD cameras are installed on the dolly symmetrically about the midline of two rails. While the dolly move along the railway, two CCD cameras grasp the image synchronously, and a computer real-time process the images, the height and pull out value can be calculate out from the images.

  18. Dynamics of the Molten Contact Line

    NASA Technical Reports Server (NTRS)

    Sonin, Ain A.; Schiaffino, Stefano

    1996-01-01

    In contrast to the ordinary contact line problem, virtually no information is available on the similar problem associated with a molten material spreading on a solid which is below the melt's fusion point. The latter is a more complex problem which heat transfer and solidification take place simultaneously with spreading, and requires answers not only for the hot melt's advance speed over the cold solid as a function of contact angle, but also for how one is to predict the point of the molten contact line's arrest by freezing. This issues are of importance in evolving methods of materials processing. The purpose of our work is to develop, based on both experiments and theory, an understanding of the dynamic processes that occur when a molten droplet touches a subcooled solid, spreads partly over it by capillary action, and freezes. We seek answers to the following basic questions. First, what is the relationship between the melt's contact line speed and the apparent (dynamic) contact angle? Secondly, at what point will the contact line modon be arrested by freezing? The talk will describe three components of our work: (1) deposition experiments with small molten droplets; (2) investigation of the dynamics of the molten contact line by means of a novel forced spreading method; and (3) an attempt to provide a theoretical framework for answering the basic questions posed above.

  19. Interfacial closure of contacting surfaces

    NASA Astrophysics Data System (ADS)

    Rieutord, F.; Rauer, C.; Moriceau, H.

    2014-08-01

    Understanding the contact between solid surfaces is a long-standing problem which has a strong impact on the physics of many processes such as adhesion, friction, lubrication and wear. Experimentally, the investigation of solid/solid interfaces remains challenging today, due to the lack of experimental techniques able to provide sub-nanometer scale information on interfaces buried between millimeters of materials. Yet, a strong interest exists improving the modeling of contact mechanics of materials in order to adjust their interface properties (e.g., thermal transport, friction). We show here that the essential features of the residual gap between contacting surfaces can be measured using high energy X-ray synchrotron reflectivity. The presence of this nano-gap is general to the contact of solids. In some special case however, it can be removed when attractive forces take over repulsive contributions, depending on both height and wavelength of asperity distributions (roughness). A criterion for this instability is established in the standard case of van der Waals attractive forces and elastic asperity compression repulsive forces (Hertz model). This collapse instability is confirmed experimentally in the case of silicon direct bonding, using high-energy X-ray synchrotron reflectivity and adhesion energy measurements. The possibility to achieve fully closed interfaces at room temperature opens interesting perspectives to build stronger assemblies with smaller thermal budgets.

  20. [Contact dermatitis in Dakar].

    PubMed

    Niang, S O

    2007-01-01

    Because of the widespread repartition of allergens, allergic contact dermatitis is the most common inflammatory skin disease. It's the best model of dilated hypersensibility mediated by T lymphocytes cells. Atopic dermatitis and irritative dermatitis are to be distinguished to contact dermatitis. The aetiological diagnosis is the most important step of management of patients with that disease because it's the best way to avoid recurrences. The identification of cause is based on aetiological interrogatory and epicutaneous tests with 23 allergens completed with personnel products and specialised tests. Contact dermatitis can be classified according to results of aetiological management. In occupational contact dermatitis, contact dermatitis due to drugs, to metals, cosmetics, clothes and accessory and proteins. Management of patients with contact dermatitis is based on individual eviction, protection, cosmetovigilance, declaration of occupational dermatosis and allergovigilance. PMID:19102084

  1. Optical contact micrometer

    SciTech Connect

    Jacobson, Steven D.

    2014-08-19

    Certain examples provide optical contact micrometers and methods of use. An example optical contact micrometer includes a pair of opposable lenses to receive an object and immobilize the object in a position. The example optical contact micrometer includes a pair of opposable mirrors positioned with respect to the pair of lenses to facilitate viewing of the object through the lenses. The example optical contact micrometer includes a microscope to facilitate viewing of the object through the lenses via the mirrors; and an interferometer to obtain one or more measurements of the object.

  2. Identifying problem and compulsive gamblers.

    PubMed Central

    van Es, R.

    2000-01-01

    OBJECTIVE: To present a meta-analysis of current research on the prevalence, identification, and treatment of problem and compulsive gamblers. QUALITY OF EVIDENCE: Problem and compulsive gambling was not a socio-scientific concern until the last two decades. Hence research on this topic is limited. The summary and analysis for this paper relied on computer searches of journal and news abstracts in addition to direct contact with organizations addressing the identification and treatment of compulsive gamblers. MAIN MESSAGE: An estimated 5% of those who gamble run into problems. About 1% of those who gamble are predicted to experience serious problems. Successful treatment of problem and compulsive gambling continues to be a challenge. Although cognitive therapy has been the favoured approach, a combination of several therapeutic approaches is advocated. CONCLUSIONS: Problem and compulsive gambling can present a real health threat. As with other addictions, treatment strategies continue to be a baffling social problem. Aware and informed physicians can have a pivotal role in the difficult process of identifying, acknowledging, and remediating problem and compulsive gambling. PMID:10907572

  3. Evaluation of the electrical contact area in contact-mode scanning probe microscopy

    SciTech Connect

    Celano, Umberto E-mail: u.celano@gmail.com; Chintala, Ravi Chandra; Vandervorst, Wilfried; Hantschel, Thomas; Giammaria, Guido; Conard, Thierry; Bender, Hugo

    2015-06-07

    The tunneling current through an atomic force microscopy (AFM) tip is used to evaluate the effective electrical contact area, which exists between tip and sample in contact-AFM electrical measurements. A simple procedure for the evaluation of the effective electrical contact area is described using conductive atomic force microscopy (C-AFM) in combination with a thin dielectric. We characterize the electrical contact area for coated metal and doped-diamond tips operated at low force (<200 nN) in contact mode. In both cases, we observe that only a small fraction (<10 nm{sup 2}) of the physical contact (∼100 nm{sup 2}) is effectively contributing to the transport phenomena. Assuming this reduced area is confined to the central area of the physical contact, these results explain the sub-10 nm electrical resolution observed in C-AFM measurements.

  4. Ultraviolet disinfection of contact lenses.

    PubMed

    Harris, M G; Fluss, L; Lem, A; Leong, H

    1993-10-01

    To evaluate the efficacy of ultraviolet (UV) radiation as a method of disinfecting contact lenses and their storage solutions, we contaminated soft lenses (Bausch & Lomb Optima 38), rigid gas permeable (RGP) lenses (Oxyflow F-30), and their storage solutions with three common bacteria. Escherichia coli (E.c.), Staphylococcus epidermis (S.e.), and Serratia marcescens (S.m.). The storage solutions used were saline solution and RGP conditioning solution. We determined the exposure times to 253.7-nm wavelength UV radiation necessary to disinfect the contact lenses and solutions. The decimal reduction values (D values) found for UV radiation were 10 to 200 hundred times shorter than reported for currently available disinfection systems. For E.c., sterilization was attained after 100 s of exposure. For S.e. and S.m., sterilization occurred after 300 s of exposure. Different contact lens solutions transmit UV radiation to various degrees, with saline solution passing more than 90% of the UV radiation. Thus, our results indicate that UV radiation is an effective and rapid method of disinfecting contact lenses and their storage solutions. PMID:8247487

  5. Ultraviolet disinfection of contact lenses.

    PubMed

    Harris, M G; Fluss, L; Lem, A; Leong, H

    1993-10-01

    To evaluate the efficacy of ultraviolet (UV) radiation as a method of disinfecting contact lenses and their storage solutions, we contaminated soft lenses (Bausch & Lomb Optima 38), rigid gas permeable (RGP) lenses (Oxyflow F-30), and their storage solutions with three common bacteria. Escherichia coli (E.c.), Staphylococcus epidermis (S.e.), and Serratia marcescens (S.m.). The storage solutions used were saline solution and RGP conditioning solution. We determined the exposure times to 253.7-nm wavelength UV radiation necessary to disinfect the contact lenses and solutions. The decimal reduction values (D values) found for UV radiation were 10 to 200 hundred times shorter than reported for currently available disinfection systems. For E.c., sterilization was attained after 100 s of exposure. For S.e. and S.m., sterilization occurred after 300 s of exposure. Different contact lens solutions transmit UV radiation to various degrees, with saline solution passing more than 90% of the UV radiation. Thus, our results indicate that UV radiation is an effective and rapid method of disinfecting contact lenses and their storage solutions.

  6. Language Contact: An Introduction.

    ERIC Educational Resources Information Center

    Thomason, Sarah G.

    This book surveys situations in which language contact arises and focuses on what happens to the languages themselves: sometimes nothing, sometimes the incorporation of new words, sometimes the spread of new sounds and sentence structures across many languages and wide swathes of territory. It outlines the origins and results of contact-induced…

  7. Noneczematous Contact Dermatitis

    PubMed Central

    Foti, Caterina; Vestita, Michelangelo; Angelini, Gianni

    2013-01-01

    Irritant or allergic contact dermatitis usually presents as an eczematous process, clinically characterized by erythematoedematovesicous lesions with intense itching in the acute phase. Such manifestations become erythematous-scaly as the condition progresses to the subacute phase and papular-hyperkeratotic in the chronic phase. Not infrequently, however, contact dermatitis presents with noneczematous features. The reasons underlying this clinical polymorphism lie in the different noxae and contact modalities, as well as in the individual susceptibility and the various targeted cutaneous structures. The most represented forms of non-eczematous contact dermatitis include the erythema multiforme-like, the purpuric, the lichenoid, and the pigmented kinds. These clinical entities must obviously be discerned from the corresponding “pure” dermatitis, which are not associated with contact with exogenous agents. PMID:24109520

  8. Contact dermatitis in athletes.

    PubMed

    Kockentiet, Brett; Adams, Brian B

    2007-06-01

    Athletes face numerous hazards in their daily activities. An athlete's skin, in particular, endures repeated exposure to trauma, heat, moisture, and numerous allergens and chemicals. These factors combine with other unique and less well-defined genetically predisposing factors in the athlete's skin to cause both allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD). As with other cases of contact dermatitis, these eruptions in athletes present as a spectrum of acute to subacute to chronic dermatitis. Recognizing the unique environmental irritants and allergens encountered by athletes is paramount to facilitate appropriate therapy and prevention. This review comprehensively examines the literature on contact dermatitis in athletes. The different types of contact dermatitis have been classified under sport-specific subheadings. Furthermore, within each subheading, both ACD and ICD types are discussed.

  9. Multibody dynamic simulation of knee contact mechanics

    PubMed Central

    Bei, Yanhong; Fregly, Benjamin J.

    2006-01-01

    Multibody dynamic musculoskeletal models capable of predicting muscle forces and joint contact pressures simultaneously would be valuable for studying clinical issues related to knee joint degeneration and restoration. Current three-dimensional multi-body knee models are either quasi-static with deformable contact or dynamic with rigid contact. This study proposes a computationally efficient methodology for combining multibody dynamic simulation methods with a deformable contact knee model. The methodology requires preparation of the articular surface geometry, development of efficient methods to calculate distances between contact surfaces, implementation of an efficient contact solver that accounts for the unique characteristics of human joints, and specification of an application programming interface for integration with any multibody dynamic simulation environment. The current implementation accommodates natural or artificial tibiofemoral joint models, small or large strain contact models, and linear or nonlinear material models. Applications are presented for static analysis (via dynamic simulation) of a natural knee model created from MRI and CT data and dynamic simulation of an artificial knee model produced from manufacturer’s CAD data. Small and large strain natural knee static analyses required 1 min of CPU time and predicted similar contact conditions except for peak pressure, which was higher for the large strain model. Linear and nonlinear artificial knee dynamic simulations required 10 min of CPU time and predicted similar contact force and torque but different contact pressures, which were lower for the nonlinear model due to increased contact area. This methodology provides an important step toward the realization of dynamic musculoskeletal models that can predict in vivo knee joint motion and loading simultaneously. PMID:15564115

  10. Hertzian contact in two and three dimensions

    NASA Technical Reports Server (NTRS)

    Tripp, J. H.

    1985-01-01

    The basic solution to the problem of mechanical contact between elastically deforming solids was proposed by Hertz over a century ago and has been used by tribologists and others ever since in a steadily increasing number of applications. While the theoretical development is not conceptually difficult and treatments exist to suit all tastes, it is nonetheless interesting to trace the relationships among the solutions in different dimensions. Such an approach is used herein to shed light on the curious and sometimes perplexing behavior of line contacts. A number of the more frequently used contact expressions together as a convenient reference and for comparative purposes.

  11. FAST ACTING CURRENT SWITCH

    DOEpatents

    Batzer, T.H.; Cummings, D.B.; Ryan, J.F.

    1962-05-22

    A high-current, fast-acting switch is designed for utilization as a crowbar switch in a high-current circuit such as used to generate the magnetic confinement field of a plasma-confining and heat device, e.g., Pyrotron. The device particularly comprises a cylindrical housing containing two stationary, cylindrical contacts between which a movable contact is bridged to close the switch. The movable contact is actuated by a differential-pressure, airdriven piston assembly also within the housing. To absorb the acceleration (and the shock imparted to the device by the rapidly driven, movable contact), an adjustable air buffer assembly is provided, integrally connected to the movable contact and piston assembly. Various safety locks and circuit-synchronizing means are also provided to permit proper cooperation of the invention and the high-current circuit in which it is installed. (AEC)

  12. Quick, stable, safe and economical preheating of glass mat reinforced thermoplastics in a contact heating oven

    SciTech Connect

    Michaeli, W.; Starke, J.

    1993-12-31

    Glass mat reinforced thermoplastics (GMT) which belong to the group of sheet thermoplastic composites (STC) are processed in compression moulding for structural parts. Before moulding the material, it has to be preheated currently by IR-radiation or by air convection. Using a contact heating oven, preheating can be speeded up combined with a significant higher energetic efficiency. But up to now, operation using the contact heating method failed due to the tackiness of the matrix material in solid state. IKV has recently created a solution for the problem of tackiness by transporting the glass mat reinforced material between two belts coated with PTFE through a contact oven. This preheating line includes a shock-cooler to quickly cool down a thin layer of the GMT`s surface. By this, separating the GMT from the PTFE without leaving particles on the belt is possible. The contact heating method not only includes the advantage of a significant higher energetic efficiency, but also benefits in processing. The risk of matrix degradation is distinctly reduced in comparison to other preheating methods, since the material does not expand in thickness for more than 200% and therefore air cannot come intensively into contact with the material. Consequently, the contact preheating is well qualified for matrix materials susceptible for oxidation. In this paper the physical coherence, the adhesion and the cohesion of GMT, are, described. Furthermore experimental results with a contact preheating line are presented.

  13. Development of a second generation rolling contact fatigue tester

    NASA Astrophysics Data System (ADS)

    Deshmukh, Satyam U.

    Contact fatigue failure has been in research since the early twentieth century. The need for a second generation sliding-rolling contact fatigue tester was proposed by Gregory Dvorak and Dr. Marcellin Zahui. The first generation RCF tester was used for testing super finishing processes for gear surfaces. The second generation RCF tester was funded by the Advanced Engineering Materials lab of University of North Dakota. Verification of the second generation Rolling Contact Fatigue Tester will be discussed in this thesis including the design details, assembly and testing procedure and to discuss its different parameters. The tester will have the capability of testing hollow specimens using a bobbin eddy current testing probe. This tester will allow a wide range of experiments and is not built for one specific purpose. An eddy current device is used for detecting cracks. The loading force is applied using hydraulic cylinders and a hydraulic power unit. Before testing began, the machine was run for some time at full speed. A lot of minor problems were detected and fixed. Three specimens of AISI 8620 were tested in this tester. All tests gave results matching with some of the other well-known RCF testers. These tests were performed to evaluate mechanical limits of the tester and to evaluate the software performance of the tester.

  14. Frictionless contact of aircraft tires

    NASA Technical Reports Server (NTRS)

    Kim, Kyun O.; Tanner, John A.; Noor, Ahmed K.

    1989-01-01

    A computational procedure for the solution of frictionless contact problems of spacecraft tires was developed using a two-dimensional laminated anisotropic shell theory incorporating the effects of variations in material and geometric parameters, transverse shear deformation, and geometric nonlinearities to model the nose-gear tire of a space shuttle. Numerical results are presented for the case when the nose-gear tire is subjected to inflation pressure and pressed against a rigid pavement. The results are compared with experimental results obtained at NASA Langley, demonstrating a high accuracy of the model and the effectiveness of the computational procedure.

  15. Allergic contact dermatitis.

    PubMed

    Becker, Detlef

    2013-07-01

    Allergic contact dermatitis is a frequent inflammatory skin disease. The suspected diagnosis is based on clinical symptoms, a plausible contact to allergens and a suitable history of dermatitis. Differential diagnoses should be considered only after careful exclusion of any causal contact sensitization. Hence, careful diagnosis by patch testing is of great importance. Modifications of the standardized test procedure are the strip patch test and the repeated open application test. The interpretation of the SLS (sodium lauryl sulfate) patch test as well as testing with the patients' own products and working materials are potential sources of error. Accurate patch test reading is affected in particular by the experience and individual factors of the examiner. Therefore, a high degree of standardization and continuous quality control is necessary and may be supported by use of an online patch test reading course made available by the German Contact Dermatitis Research Group. A critical relevance assessment of allergic patch test reactions helps to avoid relapses and the consideration of differential diagnoses. Any allergic test reaction should be documented in an allergy ID card including the INCI name, if appropriate. The diagnostics of allergic contact dermatitis is endangered by a seriously reduced financing of patch testing by the German statutory health insurances. Restrictive regulations by the German Drug Law block the approval of new contact allergens for routine patch testing. Beside the consistent avoidance of allergen contact, temporary use of systemic and topical corticosteroids is the therapy of first choice.

  16. A theoretical study of optical contact of vitreous silica

    NASA Technical Reports Server (NTRS)

    Barber, T. D.

    1972-01-01

    Optical contact has been proposed as a method of bonding quartz parts of the Stanford relativity satellite. The theory of the van der Waals force is outlined and applied to the problem of optical contact. The effect of various contaminations is discussed and a program of experimentation for further study of the problem is presented.

  17. Contact microscopy with synchrotron radiation

    SciTech Connect

    Panessa-Warren, B.J.

    1985-10-01

    Soft x-ray contact microscopy with synchrotron radiation offers the biologist and especially the microscopist, a way to morphologically study specimens that could not be imaged by conventional TEM, STEM or SEM methods (i.e. hydrated samples, samples easily damaged by an electron beam, electron dense samples, thick specimens, unstained low contrast specimens) at spatial resolutions approaching those of the TEM, with the additional possibility to obtain compositional (elemental) information about the sample as well. Although flash x-ray sources offer faster exposure times, synchrotron radiation provides a highly collimated, intense radiation that can be tuned to select specific discrete ranges of x-ray wavelengths or specific individual wavelengths which optimize imaging or microanalysis of a specific sample. This paper presents an overview of the applications of x-ray contact microscopy to biological research and some current research results using monochromatic synchrotron radiation to image biological samples. 24 refs., 10 figs.

  18. Sensing with Superconducting Point Contacts

    PubMed Central

    Nurbawono, Argo; Zhang, Chun

    2012-01-01

    Superconducting point contacts have been used for measuring magnetic polarizations, identifying magnetic impurities, electronic structures, and even the vibrational modes of small molecules. Due to intrinsically small energy scale in the subgap structures of the supercurrent determined by the size of the superconducting energy gap, superconductors provide ultrahigh sensitivities for high resolution spectroscopies. The so-called Andreev reflection process between normal metal and superconductor carries complex and rich information which can be utilized as powerful sensor when fully exploited. In this review, we would discuss recent experimental and theoretical developments in the supercurrent transport through superconducting point contacts and their relevance to sensing applications, and we would highlight their current issues and potentials. A true utilization of the method based on Andreev reflection analysis opens up possibilities for a new class of ultrasensitive sensors. PMID:22778630

  19. Study of barrier height and trap centers of Au/n-Hg{sub 3}In{sub 2}Te{sub 6} Schottky contacts by current-voltage (I-V) characteristics and deep level transient spectroscopy

    SciTech Connect

    Li, Yapeng; Fu, Li Sun, Jie; Wang, Xiaozhen

    2015-02-28

    The temperature-dependent electrical characteristics of the Au/n-Hg{sub 3}In{sub 2}Te{sub 6} Schottky contact have been studied at the temperature range of 140 K–315 K. Based on the thermionic emission theory, the ideality factor and Schottky barrier height were calculated to decrease and increase from 3.18 to 1.88 and 0.39 eV to 0.5 eV, respectively, when the temperature rose from 140 K to 315 K. This behavior was interpreted by the lateral inhomogeneities of Schottky barrier height at the interface of Au/n-Hg{sub 3}In{sub 2}Te{sub 6} contact, which was shown by the plot of zero-bias barrier heights Φ{sub bo} versus q/2kT. Meanwhile, it was found that the Schottky barrier height with a Gaussian distribution was 0.67 eV and the standard deviation σ{sub 0} was about 0.092 eV, indicating that the uneven distribution of barrier height at the interface region. In addition, the mean value of Φ{sup ¯}{sub b0} and modified Richardson constant was determined to be 0.723 eV and 62.8 A/cm{sup 2}K{sup 2} from the slope and intercept of the ln(I{sub o}/T{sup 2}) – (qσ{sub 0}{sup 2}/2k{sup 2}T{sup 2}) versus q/kT plot, respectively. Finally, two electron trap centers were observed at the interface of Au/n-Hg{sub 3}In{sub 2}Te{sub 6} Schottky contact by means of deep level transient spectroscopy.

  20. Telescopic vision contact lens

    NASA Astrophysics Data System (ADS)

    Tremblay, Eric J.; Beer, R. Dirk; Arianpour, Ashkan; Ford, Joseph E.

    2011-03-01

    We present the concept, optical design, and first proof of principle experimental results for a telescopic contact lens intended to become a visual aid for age-related macular degeneration (AMD), providing magnification to the user without surgery or external head-mounted optics. Our contact lens optical system can provide a combination of telescopic and non-magnified vision through two independent optical paths through the contact lens. The magnified optical path incorporates a telescopic arrangement of positive and negative annular concentric reflectors to achieve 2.8x - 3x magnification on the eye, while light passing through a central clear aperture provides unmagnified vision.

  1. Optical contacting of quartz

    NASA Technical Reports Server (NTRS)

    Payne, L. L.

    1982-01-01

    The strength of the bond between optically contacted quartz surfaces was investigated. The Gravity Probe-B (GP-B) experiment to test the theories of general relativity requires extremely precise measurements. The quartz components of the instruments to make these measurements must be held together in a very stable unit. Optical contacting is suggested as a possible method of joining these components. The fundamental forces involved in optical contacting are reviewed and relates calculations of these forces to the results obtained in experiments.

  2. An H-formulation-based three-dimensional hysteresis loss modelling tool in a simulation including time varying applied field and transport current: the fundamental problem and its solution

    NASA Astrophysics Data System (ADS)

    Stenvall, A.; Lahtinen, V.; Lyly, M.

    2014-10-01

    When analytic solutions are not available, finite-element-based tools can be used to simulate hysteresis losses in superconductors with various shapes. A widely used tool for the corresponding magnetoquasistatic problem is based on the H-formulation, where H is the magnetic field intensity, eddy current model. In this paper, we study this type of tool in a three-dimensional simulation problem. We consider a case where we simultaneously apply both a time-varying external magnetic field and a transport current to a twisted wire. We show how the modelling decisions (air has high finite resistivity and applied field determines the boundary condition) affect the current density distribution along the wire. According to the results, the wire carries the imposed net current only on the boundary of the modelling domain, but not inside it. The current diffuses to the air and back to the boundary. To fix this problem, we present another formulation where air is treated as a region with 0 conductivity. Correspondingly, we express H in the air with a scalar potential and a cohomology basis function which considers the net current condition. As shown in this paper, this formulation does not fail in these so-called AC-AC (time varying transport current and applied magnetic field) simulations.

  3. Surrogate Modeling of Deformable Joint Contact using Artificial Neural Networks

    PubMed Central

    Eskinazi, Ilan; Fregly, Benjamin J.

    2016-01-01

    Deformable joint contact models can be used to estimate loading conditions for cartilage-cartilage, implant-implant, human-orthotic, and foot-ground interactions. However, contact evaluations are often so expensive computationally that they can be prohibitive for simulations or optimizations requiring thousands or even millions of contact evaluations. To overcome this limitation, we developed a novel surrogate contact modeling method based on artificial neural networks (ANNs). The method uses special sampling techniques to gather input-output data points from an original (slow) contact model in multiple domains of input space, where each domain represents a different physical situation likely to be encountered. For each contact force and torque output by the original contact model, a multi-layer feed-forward ANN is defined, trained, and incorporated into a surrogate contact model. As an evaluation problem, we created an ANN-based surrogate contact model of an artificial tibiofemoral joint using over 75,000 evaluations of a fine-grid elastic foundation (EF) contact model. The surrogate contact model computed contact forces and torques about 1000 times faster than a less accurate coarse grid EF contact model. Furthermore, the surrogate contact model was seven times more accurate than the coarse grid EF contact model within the input domain of a walking motion. For larger input domains, the surrogate contact model showed the expected trend of increasing error with increasing domain size. In addition, the surrogate contact model was able to identify out-of-contact situations with high accuracy. Computational contact models created using our proposed ANN approach may remove an important computational bottleneck from musculoskeletal simulations or optimizations incorporating deformable joint contact models. PMID:26220591

  4. Immunotherapy of allergic contact dermatitis.

    PubMed

    Spiewak, Radoslaw

    2011-08-01

    The term 'immunotherapy' refers to treating diseases by inducing, enhancing or suppressing immune responses. As allergy is an excessive, detrimental immune reaction to otherwise harmless environmental substances, immunotherapy of allergic disease is aimed at the induction of tolerance toward sensitizing antigens. This article focuses on the historical developments, present state and future outlook for immunotherapy with haptens as a therapeutic modality for allergic contact dermatitis. Inspired by the effectiveness of immunotherapy in respiratory allergies, attempts were undertaken at curing allergic contact dermatitis by means of controlled administration of the sensitizing haptens. Animal and human experiments confirmed that tolerance to haptens can be induced most effectively when the induction of tolerance precedes attempted sensitization. In real life, however, therapy is sought by people who are already sensitized and an effective reversal of hypersensitivity seems more difficult to achieve. Decades of research on Rhus hypersensitivity led to a conclusion that immunotherapy can suppress Rhus dermatitis, however, only to a limited degree, for a short period of time, and at a high risk of side effects, which makes this method therapeutically unprofitable. Methodological problems with most available studies of immunotherapy of contact allergy to nickel make any definite conclusions impossible at this stage.

  5. Fragrance allergic contact dermatitis.

    PubMed

    Cheng, Judy; Zug, Kathryn A

    2014-01-01

    Fragrances are a common cause of allergic contact dermatitis in Europe and in North America. They can affect individuals at any age and elicit a spectrum of reactions from contact urticaria to systemic contact dermatitis. Growing recognition of the widespread use of fragrances in modern society has fueled attempts to prevent sensitization through improved allergen identification, labeling, and consumer education. This review provides an overview and update on fragrance allergy. Part 1 discusses the epidemiology and evaluation of suspected fragrance allergy. Part 2 reviews screening methods, emerging fragrance allergens, and management of patients with fragrance contact allergy. This review concludes by examining recent legislation on fragrances and suggesting potential additions to screening series to help prevent and detect fragrance allergy.

  6. Occupational Contact Dermatitis

    PubMed Central

    2008-01-01

    Occupational contact dermatitis accounts for 90% of all cases of work-related cutaneous disorders. It can be divided into irritant contact dermatitis, which occurs in 80% of cases, and allergic contact dermatitis. In most cases, both types will present as eczematous lesions on exposed parts of the body, notably the hands. Accurate diagnosis relies on meticulous history taking, thorough physical examination, careful reading of Material Safety Data Sheets to distinguish between irritants and allergens, and comprehensive patch testing to confirm or rule out allergic sensitization. This article reviews the pathogenesis and clinical manifestations of occupational contact dermatitis and provides diagnostic guidelines and a rational approach to management of these often frustrating cases. PMID:20525126

  7. Contacting American Overseas Schools.

    ERIC Educational Resources Information Center

    Engelhardt, David

    1993-01-01

    Provides contacts for architects or educational consultants who wish to work overseas. Cites a directory, newsletters, newspapers, and associations focused on educators involved with independent overseas schools that are organized around the United States curriculum. (MLF)

  8. Relay contact monitoring system

    SciTech Connect

    Mehta, V.

    1994-01-11

    A switching system for switching on and off heating and air conditioning units in an environmental control system. The switching system includes a thermostat and a relay conductively coupled to the thermostat. The relay has a contact, which is responsive to a change signal for changing its position. The system further includes a programmable monitor having predetermined positions stored in a memory. The monitor is conductively coupled to the contact and to the thermostat for continually determining the position of the contact, and for sending a change signal to the relay for switching the position of the contact, as needed, to be in conformance with a predetermined position stored in the memory. 3 figs.

  9. Microwave characterization of Ti/Au-graphene contacts

    NASA Astrophysics Data System (ADS)

    Andersson, M. A.; Vorobiev, A.; Sun, J.; Yurgens, A.; Gevorgian, S.; Stake, J.

    2013-10-01

    In this paper, we report on a microwave characterization of the interface between Ti/Au contacts and chemical vapor deposition graphene using structures of Corbino geometry, with primary focus on extracting and modeling the capacitance associated with the contact region. It is found that with the current contact resistivity, ρc˜10-6 Ωcm2, the contact capacitance, on the order Cc˜1 μF /cm2, has a negligible effect on microwave transmission through the contact below ˜100 GHz. Finally, a parallel plate capacitance model for the contact is presented.

  10. Design and fabrication of wraparound contact silicon solar cells

    NASA Technical Reports Server (NTRS)

    Scott-Monck, J. A.; Stella, P. M.; Avery, J. E.

    1972-01-01

    Both dielectric insulation and etched junction contact techniques were evaluated for use in wraparound contact cell fabrication. Since a suitable process for depositing the dielectrics was not achieved, the latter approach was taken. The relationship between loss of back contact and power degradation due to increased series resistance was established and used to design a simple contact configuration for 10 ohm-cm etched wraparound junction contact N/P cells. A slightly deeper junction significantly improved cell curve shape and the associated loss of current was regained by using thinner contact grid fingers. One thousand cells with efficiencies greater than 10.5% were fabricated to demonstrate the process.

  11. The impact of contact

    NASA Astrophysics Data System (ADS)

    Finney, B.

    1986-10-01

    Scenarios of the impact on human society of radio contact with an extraterrestrial civilization are presented. Some believe that contact with advanced extraterrestrials would quickly devastate the human spirit, while others believe that these super-intelligent beings would show the inhabitants of the earth how to live in peace. It is proposed that the possible existence of extraterrestrial civilizations and the development of means of studying and communicating with them need to be considered.

  12. ELECTRIC CONTACT MEANS

    DOEpatents

    Grear, J.W. Jr.

    1959-03-10

    A switch adapted to maintain electrical connections under conditions of vibration or acceleration is described. According to the invention, thc switch includes a rotatable arm carrying a conductive bar arranged to close against two contacts spaced in the same plane. The firm and continuous engagement of the conductive bar with the contacts is acheived by utilizeing a spring located betwenn the vbar and athe a rem frzme and slidable mounting the bar in channel between two arms suspendef from the arm frame.

  13. Current titles

    SciTech Connect

    1995-07-01

    This booklet is published for those interested in current research being conducted at the National Center for Electron Microscopy. The NCEM is a DOE-designated national user facility and is available at no charge to qualified researchers. Access is controlled by an external steering committee. Interested researchers may contact Gretchen Hermes at (510) 486-5006 or address below for a User`s Guide. Copies of available papers can be ordered from: Theda Crawford National Center for Electron Microscopy, Lawrence Berkeley Laboratory, One Cyclotron Rd., MS72, Berkeley, California, USA 94720.

  14. Lettuce contact allergy.

    PubMed

    Paulsen, Evy; Andersen, Klaus E

    2016-02-01

    Lettuce (Lactuca sativa L.) and its varieties are important vegetable crops worldwide. They are also well-known, rarely reported, causes of contact allergy. As lettuce allergens and extracts are not commercially available, the allergy may be underdiagnosed. The aims of this article are to present new data on lettuce contact allergy and review the literature. Lettuce is weakly allergenic, and occupational cases are mainly reported. Using aimed patch testing in Compositae-allergic patients, two recent Danish studies showed prevalence rates of positive lettuce reactions of 11% and 22%. The majority of cases are non-occupational, and may partly be caused by cross-reactivity. The sesquiterpene lactone mix seems to be a poor screening agent for lettuce contact allergy, as the prevalence of positive reactions is significantly higher in non-occupationally sensitized patients. Because of the easy degradability of lettuce allergens, it is recommended to patch test with freshly cut lettuce stem and supplement this with Compositae mix. As contact urticaria and protein contact dermatitis may present as dermatitis, it is important to perform prick-to-prick tests, and possibly scratch patch tests as well. Any person who is occupationally exposed to lettuce for longer periods, especially atopics, amateur gardeners, and persons keeping lettuce-eating pets, is potentially at risk of developing lettuce contact allergy.

  15. From point contacts to spin-transfer torque

    NASA Astrophysics Data System (ADS)

    Tsoi, Maxim

    2013-03-01

    Point contacts - nanoscale electrical contacts between conductors - have been around for decades and proved to be unique experimental tools for studying the electronic transport properties of metals. Following the theoretical prediction of spin-transfer torque (STT) by John Slonczewski and Luc Berger, point contacts were instrumental for the first experimental demonstration of STT in spin-valve multilayers, thanks to extremely high current densities routinely produced in such contacts. In this talk I will briefly review the point-contact technique and its contributions to the field of current-induced control over magnetic nanostructures. M.T. is supported in part by NSF grant DMR-1207577

  16. Six challenges in measuring contact networks for use in modelling.

    PubMed

    Eames, K; Bansal, S; Frost, S; Riley, S

    2015-03-01

    Contact networks are playing an increasingly important role in epidemiology. A contact network represents individuals in a host population as nodes and the interactions among them that may lead to the transmission of infection as edges. New avenues for data collection in recent years have afforded us the opportunity to collect individual- and population-scale information to empirically describe the patterns of contact within host populations. Here, we present some of the current challenges in measuring empirical contact networks. We address fundamental questions such as defining contact; measurement of non-trivial contact properties; practical issues of bounding measurement of contact networks in space, time and scope; exploiting proxy information about contacts; dealing with missing data. Finally, we consider the privacy and ethical issues surrounding the collection of contact network data.

  17. A robust algorithm for the contact of viscoelastic materials

    NASA Astrophysics Data System (ADS)

    Spinu, S.; Cerlinca, D.

    2016-08-01

    Existing solutions for the contact problem involving viscoelastic materials often require numerical differentiation and integration, as well as resolution of transcendental equations, which can raise convergence issues. The algorithm advanced in this paper can tackle the contact behaviour of the viscoelastic materials without any convergence problems, for arbitrary contact geometry, arbitrary loading programs and complex constitutive models of linear viscoelasticity. An updated algorithm for the elastic frictionless contact, coupled with a semi-analytical method for the computation of viscoelastic displacement, is employed to solve the viscoelastic contact problem at a series of small time increments. The number of equations in the linear system resulting from the geometrical condition of deformation is set by the number of cells in the contact area, which is a priori unknown. A trial-and-error approach is implemented, resulting in a series of linear systems which are solved on evolving contact areas, until static equilibrium equations and complementarity conditions are fully satisfied for every cell in the computational domain. At any iteration, cells with negative pressure are excluded from the contact area, while cells with negative gap (i.e. cells where the contacting bodies are predicted to overlap) are reincluded. The solution is found when pressure is stabilized in relation to the imposed normal load. This robust algorithm is expected to solve a large variety of contact problems involving viscoelastic materials.

  18. Inverse Problems of Thermoelectricity

    NASA Astrophysics Data System (ADS)

    Anatychuk, L. I.; Luste, O. J.; Kuz, R. V.; Strutinsky, M. N.

    2011-05-01

    Classical thermoelectricity is based on the use of the Seebeck and Thomson effects that occur in the near-contact areas between n- and p-type materials. A conceptually different approach to thermoelectric power converter design that is based on the law of thermoelectric induction of currents is also known. The efficiency of this approach has already been demonstrated by its first applications. More than 10 basically new types of thermoelements were discovered with properties that cannot be achieved by thermocouple power converters. Therefore, further development of this concept is of practical interest. This paper provides a classification and theory for solving the inverse problems of thermoelectricity that form the basis for devising new thermoelement types. Computer methods for their solution for anisotropic and inhomogeneous media are elaborated. Regularities related to thermoelectric current excitation in anisotropic and inhomogeneous media are established. The possibility of obtaining eddy currents of a particular configuration through control of the temperature field and material parameters for the creation of new thermo- element types is demonstrated for three-dimensional (3D) models of anisotropic and inhomogeneous media.

  19. The modular approach enables a fully ab initio simulation of the contacts between 3D and 2D materials.

    PubMed

    Fediai, Artem; Ryndyk, Dmitry A; Cuniberti, Gianaurelio

    2016-10-01

    Up to now, the electrical properties of the contacts between 3D metals and 2D materials have never been computed at a fully ab initio level due to the huge number of atomic orbitals involved in a current path from an electrode to a pristine 2D material. As a result, there are still numerous open questions and controversial theories on the electrical properties of systems with 3D/2D interfaces-for example, the current path and the contact length scalability. Our work provides a first-principles solution to this long-standing problem with the use of the modular approach, a method which rigorously combines a Green function formalism with the density functional theory (DFT) for this particular contact type. The modular approach is a general approach valid for any 3D/2D contact. As an example, we apply it to the most investigated among 3D/2D contacts-metal/graphene contacts-and show its abilities and consistency by comparison with existing experimental data. As it is applicable to any 3D/2D interface, the modular approach allows the engineering of 3D/2D contacts with the pre-defined electrical properties.

  20. Comment on “Problems of UV-B radiation measurements in biological research: Critical remarks on current techniques and suggestions for improvements” by H. Tüg and M. E. M. Baumann

    NASA Astrophysics Data System (ADS)

    McKenzie, R. L.; Johnston, P. V.

    1995-05-01

    We wish to comment on the paper titled “Problems of UV-B radiation in biological research. Critical remarks on current techniques and suggestions for improvements”, by Helmut Tüg and Marcus Baumann (hereafter T&B), which appeared in the April 15 issue of Geophysical Research Letters (21, 8, 689-692, 1994).

  1. Generations of Monic Polynomials such that the Coefficients of Each Polynomial of the Next Generation Coincide with the Zeros of a Polynomial of the Current Generation, and New Solvable Many-Body Problems

    NASA Astrophysics Data System (ADS)

    Bihun, Oksana; Calogero, Francesco

    2016-07-01

    The notion of generations of monic polynomials such that the coefficients of each polynomial of the next generation coincide with the zeros of a polynomial of the current generation is introduced, and its relevance to the identification of endless sequences of new solvable many-body problems "of goldfish type" is demonstrated.

  2. The contact caveat: negative contact predicts increased prejudice more than positive contact predicts reduced prejudice.

    PubMed

    Barlow, Fiona Kate; Paolini, Stefania; Pedersen, Anne; Hornsey, Matthew J; Radke, Helena R M; Harwood, Jake; Rubin, Mark; Sibley, Chris G

    2012-12-01

    Contact researchers have largely overlooked the potential for negative intergroup contact to increase prejudice. In Study 1, we tested the interaction between contact quantity and valence on prejudice toward Black Australians (n = 1,476), Muslim Australians (n = 173), and asylum seekers (n = 293). In all cases, the association between contact quantity and prejudice was moderated by its valence, with negative contact emerging as a stronger and more consistent predictor than positive contact. In Study 2, White Americans (n = 441) indicated how much positive and negative contact they had with Black Americans on separate measures. Although both quantity of positive and negative contact predicted racism and avoidance, negative contact was the stronger predictor. Furthermore, negative (but not positive) contact independently predicted suspicion about Barack Obama's birthplace. These results extend the contact hypothesis by issuing an important caveat: Negative contact may be more strongly associated with increased racism and discrimination than positive contact is with its reduction.

  3. Toward patient-specific articular contact mechanics

    PubMed Central

    Ateshian, Gerard A.; Henak, Corinne R.; Weiss, Jeffrey A.

    2015-01-01

    The mechanics of contacting cartilage layers is fundamentally important to understanding the development, homeostasis and pathology of diarthrodial joints. Because of the highly nonlinear nature of both the materials and the contact problem itself, numerical methods such as the finite element method are typically incorporated to obtain solutions. Over the course of five decades, we have moved from an initial qualitative understanding of articular cartilage material behavior to the ability to perform complex, three-dimensional contact analysis, including multiphasic material representations. This history includes the development of analytical and computational contact analysis methods that now provide the ability to perform highly nonlinear analyses. Numerical implementations of contact analysis based on the finite element method are rapidly advancing and will soon enable patient-specific analysis of joint contact mechanics using models based on medical image data. In addition to contact stress on the articular surfaces, these techniques can predict variations in strain and strain through the cartilage layers, providing the basis to predict damage and failure. This opens up exciting areas for future research and application to patient-specific diagnosis and treatment planning applied to a variety of pathologies that affect joint function and cartilage homeostasis. PMID:25698236

  4. Toward patient-specific articular contact mechanics.

    PubMed

    Ateshian, Gerard A; Henak, Corinne R; Weiss, Jeffrey A

    2015-03-18

    The mechanics of contacting cartilage layers is fundamentally important to understanding the development, homeostasis and pathology of diarthrodial joints. Because of the highly nonlinear nature of both the materials and the contact problem itself, numerical methods such as the finite element method are typically incorporated to obtain solutions. Over the course of five decades, we have moved from an initial qualitative understanding of articular cartilage material behavior to the ability to perform complex, three-dimensional contact analysis, including multiphasic material representations. This history includes the development of analytical and computational contact analysis methods that now provide the ability to perform highly nonlinear analyses. Numerical implementations of contact analysis based on the finite element method are rapidly advancing and will soon enable patient-specific analysis of joint contact mechanics using models based on medical image data. In addition to contact stress on the articular surfaces, these techniques can predict variations in strain and strain through the cartilage layers, providing the basis to predict damage and failure. This opens up exciting areas for future research and application to patient-specific diagnosis and treatment planning applied to a variety of pathologies that affect joint function and cartilage homeostasis.

  5. Contact Lenses for Vision Correction

    MedlinePlus

    ... Contact Lenses Colored Contact Lenses Contact Lenses for Vision Correction Written by: Kierstan Boyd Reviewed by: Brenda ... on the surface of the eye. They correct vision like eyeglasses do and are safe when used ...

  6. Acrylate Systemic Contact Dermatitis.

    PubMed

    Sauder, Maxwell B; Pratt, Melanie D

    2015-01-01

    Acrylates, the 2012 American Contact Dermatitis Society allergen of the year, are found in a range of products including the absorbent materials within feminine hygiene pads. When fully polymerized, acrylates are nonimmunogenic; however, if not completely cured, the monomers can be potent allergens.A 28-year-old woman is presented, who had her teeth varnished with Isodan (Septodont, Saint-Maur-des-Fossés, France) containing HEMA (2-hydroxyethyl methacrylate) with no initial reaction. Approximately 1 month later, the patient developed a genital dermatitis secondary to her feminine hygiene pads. The initial reaction resolved, but 5 months later, the patient developed a systemic contact dermatitis after receiving a second varnishing.The patient was dramatically patch test positive to many acrylates. This case demonstrates a reaction to likely unpolymerized acrylates within a feminine hygiene pad, as well as broad cross-reactivity or cosensitivity to acrylates, and possibly a systemic contact dermatitis with systemic re-exposure to unpolymerized acrylates.

  7. Aternating current photovoltaic building block

    DOEpatents

    Bower, Ward Issac; Thomas, Michael G.; Ruby, Douglas S.

    2004-06-15

    A modular apparatus for and method of alternating current photovoltaic power generation comprising via a photovoltaic module, generating power in the form of direct current; and converting direct current to alternating current and exporting power via one or more power conversion and transfer units attached to the module, each unit comprising a unitary housing extending a length or width of the module, which housing comprises: contact means for receiving direct current from the module; one or more direct current-to-alternating current inverters; an alternating current bus; and contact means for receiving alternating current from the one or more inverters.

  8. Estimation of hyper-parameters for a hierarchical model of combined cortical and extra-brain current sources in the MEG inverse problem.

    PubMed

    Morishige, Ken-ichi; Yoshioka, Taku; Kawawaki, Dai; Hiroe, Nobuo; Sato, Masa-aki; Kawato, Mitsuo

    2014-11-01

    One of the major obstacles in estimating cortical currents from MEG signals is the disturbance caused by magnetic artifacts derived from extra-cortical current sources such as heartbeats and eye movements. To remove the effect of such extra-brain sources, we improved the hybrid hierarchical variational Bayesian method (hyVBED) proposed by Fujiwara et al. (NeuroImage, 2009). hyVBED simultaneously estimates cortical and extra-brain source currents by placing dipoles on cortical surfaces as well as extra-brain sources. This method requires EOG data for an EOG forward model that describes the relationship between eye dipoles and electric potentials. In contrast, our improved approach requires no EOG and less a priori knowledge about the current variance of extra-brain sources. We propose a new method, "extra-dipole," that optimally selects hyper-parameter values regarding current variances of the cortical surface and extra-brain source dipoles. With the selected parameter values, the cortical and extra-brain dipole currents were accurately estimated from the simulated MEG data. The performance of this method was demonstrated to be better than conventional approaches, such as principal component analysis and independent component analysis, which use only statistical properties of MEG signals. Furthermore, we applied our proposed method to measured MEG data during covert pursuit of a smoothly moving target and confirmed its effectiveness. PMID:25034620

  9. Single-contact tunneling thermometry

    DOEpatents

    Maksymovych, Petro

    2016-02-23

    A single-contact tunneling thermometry circuit includes a tunnel junction formed between two objects. Junction temperature gradient information is determined based on a mathematical relationship between a target alternating voltage applied across the junction and the junction temperature gradient. Total voltage measured across the junction indicates the magnitude of the target alternating voltage. A thermal gradient is induced across the junction. A reference thermovoltage is measured when zero alternating voltage is applied across the junction. An increasing alternating voltage is applied while measuring a thermovoltage component and a DC rectification voltage component created by the applied alternating voltage. The target alternating voltage is reached when the thermovoltage is nullified or doubled by the DC rectification voltage depending on the sign of the reference thermovoltage. Thermoelectric current and current measurements may be utilized in place of the thermovoltage and voltage measurements. The system may be automated with a feedback loop.

  10. Have Confidence in Contact

    ERIC Educational Resources Information Center

    Crisp, Richard J.; Turner, Rhiannon N.

    2010-01-01

    In an article in the May-June 2009 "American Psychologist," we discussed a new approach to reducing prejudice and encouraging more positive intergroup relations (Crisp & Turner, 2009). We named the approach imagined intergroup contact and defined it as "the mental simulation of a social interaction with a member or members of an outgroup category"…

  11. The Language Contact Profile

    ERIC Educational Resources Information Center

    Freed, Barbara F.; Dewey, Dan P.; Segalowitz, Norman; Halter, Randall

    2004-01-01

    Efforts to gather data of various sorts--demographics, language-learning history, contact with native speakers, use of the language in the field--as they relate to participants in SLA research studies are inherent to understanding more about language acquisition and use. Scholars frequently develop questionnaires of their own, which are rarely…

  12. Thermal Contact Conductance

    NASA Technical Reports Server (NTRS)

    Salerno, Louis J.; Kittel, Peter

    1997-01-01

    The performance of cryogenic instruments is often a function of their operating temperature. Thus, designers of cryogenic instruments often are required to predict the operating temperature of each instrument they design. This requires accurate thermal models of cryogenic components which include the properties of the materials and assembly techniques used. When components are bolted or otherwise pressed together, a knowledge of the thermal performance of such joints are also needed. In some cases, the temperature drop across these joints represents a significant fraction of the total temperature difference between the instrument and its cooler. While extensive databases exist on the thermal properties of bulk materials, similar databases for pressed contacts do not. This has often lead to instrument designs that avoid pressed contacts or to the over-design of such joints at unnecessary expense. Although many people have made measurements of contact conductances at cryogenic temperatures, this data is often very narrow in scope and even more often it has not been published in an easily retrievable fashion, if published at all. This paper presents a summary of the limited pressed contact data available in the literature.

  13. Contact sensitivity to proflavine.

    PubMed

    Goh, C L

    1986-09-01

    Proflavine lotion is a commonly used topical antiseptic in the tropics, but its sensitizing potential was never emphasized and many who developed allergic contact dermatitis were never aware of it. In a study of 45 patients, most presented with acute or subacute dermatitis which started on the arms and legs. Concomitant cutaneous sensitivity to other medicaments and lanolin occurred in 66% of the patients.

  14. Contact Efflorescence on Demand

    NASA Astrophysics Data System (ADS)

    Davis, R. D.; Lance, S.; Gordon, J. A.; Ushijima, S.; Tolbert, M. A.

    2014-12-01

    The phase state of atmospheric aerosols (liquid vs solid) plays an important role in particle growth, cloud formation, climate impact and visibility degradation. In the atmosphere, changes in relative humidity (RH) and temperature cause phase transitions in the atmospheric particulate. Efflorescence, the process of salt crystal nucleation from an aqueous electrolyte solution upon decreasing RH, often occurs at a lower RH than the reverse process of deliquescence. It has been shown that the efflorescence RH can occur at a higher RH in the presence of a heterogeneous surface immersed in a liquid particle. Here we present a new laboratory technique using optically levitated particles to study heterogeneous efflorescence initiated by contact with an external particle. In this work, collisions between aqueous microdroplets and heterogeneous nuclei are monitored in situ using scattered laser light to quantify the number of collisions and to detect phase transitions. We find that when contact initiates the phase transition, efflorescence occurs at a higher RH than when the same heterogeneous nucleus is immersed in the particle. The results of these experiments will be discussed in the context of understanding contact nucleation on a mechanistic level and predicting the relative importance of contact efflorescence in the atmosphere.

  15. Compact contacting device

    NASA Technical Reports Server (NTRS)

    Acharya, Arun (Inventor); Gottzmann, Christian F. (Inventor); Lockett, Michael J. (Inventor); Schneider, James S. (Inventor); Victor, Richard A. (Inventor); Zawierucha, Robert (Inventor)

    1994-01-01

    An apparatus comprising a rotatable mass of structured packing for mass or heat transfer between two contacting fluids of different densities wherein the packing mass is made up of corrugated sheets of involute shape relative to the axis of the packing mass and form a logarithmic spiral curved counter to the direction of rotation.

  16. Why is adolescence a key period of alcohol initiation and who is prone to develop long-term problem use?: A review of current available data

    PubMed Central

    Petit, Géraldine; Kornreich, Charles; Verbanck, Paul; Cimochowska, Agnieska; Campanella, Salvatore

    2013-01-01

    Background Early adolescence is a key developmental period for the initiation of alcohol use, and consumption among adolescents is characterized by drinking in high quantities. At the same time, adolescence is characterized by rapid biological transformations including dramatic changes in the brain, particularly in the prefrontal cortex and the mesocorticolimbic dopamine system. Methods This article begins with an overview of the unique neural and behavioural characteristics of adolescent development that predispose these individuals to seek rewards and take risks such as initiation of drinking and high levels of alcohol intake. The authors then outline important factors associated with an increased risk for developing alcohol problems in later adolescence and young adulthood. Thereafter they address causality and the complex interplay of risk factors that lead to the development of alcohol use problems in late adolescence and young adults. Conclusions A few recommendations for the prevention of underage drinking are presented. PMID:24693359

  17. Technology Transfer: A Contact Sport

    NASA Technical Reports Server (NTRS)

    Paynter, Nina P.

    1995-01-01

    Technology transfer is a dynamic process, involving dynamic people as the bridge between NASA Langley Research Center and the outside world. This bridge, for nonaerospace applications, is known as the Technology Applications Group. The introduction of new innovations and expertise where they are needed occurs through a 'push' and 'pull' process. A 'push' occurs when a new technology is first developed with high commercial potential and then a company is found to licence or further develop the technology. The 'pull' process occurs through problem statements. A company or group will submit a written statement of what they need and the shortcomings of commercially available technology. The Technology Transfer Team (T3) reviews these problem statements and decides where NASA LaRC can offer assistance. A researcher or group of researchers are then identified who can help solve the problem and they are put in contact with the company. Depending upon the situation in either method, a Space Act Agreement (SAA), or outline of the responsibilities for each party, is developed.

  18. Direct-contact heat exchanger

    NASA Astrophysics Data System (ADS)

    Bricard, A.

    The working principle of direct contact heat exchanger, where heat transfer takes place between two immiscible fluids coming into direct contact, is described. Typical direct contact devices are outlined. A better understanding of the principles involved and the development of computational models for multiphase subsytems are concluded as stimulus for direct contact heat and mass transfer applications.

  19. Obituary--rigid contact lenses.

    PubMed

    Efron, Nathan

    2010-10-01

    Scleral and corneal rigid lenses represented 100 per cent of the contact lens market immediately prior to the invention of soft lenses in the mid-1960s. In the United Kingdom today, rigid lenses comprise 2 per cent of all new lens fits. Low rates of rigid lens fitting are also apparent in 27 other countries which have recently been surveyed. Thus, the 1998 prediction of the author that rigid lenses--also referred to as 'rigid gas permeable' (RGP) lenses or 'gas permeable' (GP) lenses--would be obsolete by the year 2010 has essentially turned out to be correct. In this obituary, the author offers 10 reasons for the demise of rigid lens fitting: initial rigid lens discomfort; intractable rigid lens-induced corneal and lid pathology; extensive soft lens advertising; superior soft lens fitting logistics; lack of rigid lens training opportunities; redundancy of the rigid lens 'problem solver' function; improved soft toric and bifocal/varifocal lenses; limited uptake of orthokeratology; lack of investment in rigid lenses; and the emergence of aberration control soft lenses. Rigid lenses are now being fitted by a minority of practitioners with specialist skills/training. Certainly, rigid lenses can no longer be considered as a mainstream form of contact lens correction. May their dear souls (bulk properties) rest in peace. PMID:20674469

  20. Exploring the Nature of Contact Freezing

    NASA Astrophysics Data System (ADS)

    Kiselev, A. A.; Hoffmann, N.; Duft, D.; Leisner, T.

    2012-12-01

    The freezing of supercooled water droplets upon contact with aerosol particles (contact nucleation of ice) is the least understood mechanism of ice formation in atmospheric clouds. Although experimental evidences suggest that some aerosols can be better IN in the contact than in the immersion mode (that is, triggering ice nucleation at higher temperature), no final explanation of this phenomena currently exists. On the other hand, the contact freezing is believed to be responsible for the enhanced rate of secondary ice formation occasionally observed in LIDAR measurements in the cold mixed phase clouds. Recently we have been able to show that the freezing of supercooled droplets electrodynamically levitated in the laminar flow containing mineral dust particles (kaolinite) is a process solely governed by a rate of collisions between the supercooled droplet and the aerosol particles. We have shown that the probability of droplet freezing on a single contact with aerosol particle may differ over an order of magnitude for kaolinite particles having different genesis and morphology. In this presentation we extend the study of contact nucleation of ice and compare the IN efficiency measured for DMA-selected kaolinite, illite and hematite particles. We show that the freezing probability increases towards unity as the temperature decreases and discuss the functional form of this temperature dependence. We explore the size dependence of the contact freezing probability and show that it scales with the surface area of the particles, thus resembling the immersion freezing behavior. However, for all minerals investigated so far, the contact freezing has been shown to dominate over immersion freezing on the short experimental time scales. Finally, based on the combined ESEM and electron microprobe analysis, we discuss the significance of particle morphology and variability of chemical composition on its IN efficiency in contact mode.

  1. Low contact resistance in epitaxial graphene devices for quantum metrology

    SciTech Connect

    Yager, Tom E-mail: ywpark@snu.ac.kr; Lartsev, Arseniy; Lara-Avila, Samuel; Kubatkin, Sergey; Cedergren, Karin; Yakimova, Rositsa; Panchal, Vishal; Kazakova, Olga; Tzalenchuk, Alexander; Kim, Kyung Ho; Park, Yung Woo E-mail: ywpark@snu.ac.kr

    2015-08-15

    We investigate Ti/Au contacts to monolayer epitaxial graphene on SiC (0001) for applications in quantum resistance metrology. Using three-terminal measurements in the quantum Hall regime we observed variations in contact resistances ranging from a minimal value of 0.6 Ω up to 11 kΩ. We identify a major source of high-resistance contacts to be due bilayer graphene interruptions to the quantum Hall current, whilst discarding the effects of interface cleanliness and contact geometry for our fabricated devices. Moreover, we experimentally demonstrate methods to improve the reproducibility of low resistance contacts (<10 Ω) suitable for high precision quantum resistance metrology.

  2. Time domain contact model for tyre/road interaction including nonlinear contact stiffness due to small-scale roughness

    NASA Astrophysics Data System (ADS)

    Andersson, P. B. U.; Kropp, W.

    2008-11-01

    Rolling resistance, traction, wear, excitation of vibrations, and noise generation are all attributes to consider in optimisation of the interaction between automotive tyres and wearing courses of roads. The key to understand and describe the interaction is to include a wide range of length scales in the description of the contact geometry. This means including scales on the order of micrometres that have been neglected in previous tyre/road interaction models. A time domain contact model for the tyre/road interaction that includes interfacial details is presented. The contact geometry is discretised into multiple elements forming pairs of matching points. The dynamic response of the tyre is calculated by convolving the contact forces with pre-calculated Green's functions. The smaller-length scales are included by using constitutive interfacial relations, i.e. by using nonlinear contact springs, for each pair of contact elements. The method is presented for normal (out-of-plane) contact and a method for assessing the stiffness of the nonlinear springs based on detailed geometry and elastic data of the tread is suggested. The governing equations of the nonlinear contact problem are solved with the Newton-Raphson iterative scheme. Relations between force, indentation, and contact stiffness are calculated for a single tread block in contact with a road surface. The calculated results have the same character as results from measurements found in literature. Comparison to traditional contact formulations shows that the effect of the small-scale roughness is large; the contact stiffness is only up to half of the stiffness that would result if contact is made over the whole element directly to the bulk of the tread. It is concluded that the suggested contact formulation is a suitable model to include more details of the contact interface. Further, the presented result for the tread block in contact with the road is a suitable input for a global tyre/road interaction model

  3. [Contact dermatitis from Agave americana].

    PubMed

    de la Cueva, Pablo; González-Carrascosa, Mateo; Campos, Minia; Leis, Vicente; Suárez, Ricardo; Lázaro, Pablo

    2005-10-01

    Numerous plant species and their derivatives can cause skin reactions through a variety of mechanisms: irritative contact dermatitis, allergic contact dermatitis, contact urticaria and photodermatitis. We present a case of irritative contact dermatitis after exposure to the sap of Agave americana. The skin symptoms in this case have only been described on rare occasions; although this condition usually presents with a papulovesicular rash, in this patient it appeared as purpuric lesions in the contact area.

  4. [Contact eczema in patients with leg ulcers].

    PubMed

    Degreef, H; Dooms-Goossens, A; Gladys, K

    1986-01-01

    Patients with leg ulcers or varicose eczema suffer much more often from contact eczema due to the local application of pharmaceutical preparations than patients suffering from other dermatological problems (even those of eczematous origin). This contact allergy may concern not only the active ingredient but also the excipient, the preservative, or even the perfume. In all cases of leg ulcers, of varicose eczema, but also of badly healed ulcers, epicutaneous tests should be carried out with all the components of the pharmaceutical preparations concerned. Moreover, the pharmaceutical industry really must perfect non-allergenic preparations.

  5. Allergic contact dermatitis in atopic dermatitis.

    PubMed

    Lever, R; Forsyth, A

    1992-01-01

    Of 73 adult patients attending a clinic specially provided to treat patients with atopic dermatitis, 31 (42%) showed one or more positive patch reaction on contact testing. There was a striking female preponderance in the patch test positive group (26F:5M) in contrast to those with negative test results (9F:17M). The commonest allergens identified were fragrances in 13 patients, nickel (7), rubber (5), lanolin (4) and formaldehyde (3). In 21 patients, topical preparations, cosmetic or medically prescribed, could be implicated. Contact sensitivity seems to be relatively common in adult patients who have a continuing problem with their atopic dermatitis. Recognizing this sensitization may be important in their management.

  6. Semiconductor ohmic contact

    NASA Technical Reports Server (NTRS)

    Hawrylo, Frank Zygmunt (Inventor); Kressel, Henry (Inventor)

    1977-01-01

    A semiconductor device has one surface of P type conductivity material having a wide energy bandgap and a large crystal lattice parameter. Applied to the P type surface of the semiconductor device is a degenerate region of semiconductor material, preferably a group III-V semiconductor material, having a narrower energy bandgap. The degenerate region is doped with tin to increase the crystal lattice of the region to more closely approximate the crystal lattice of the one surface of the semiconductor device. The degenerate region is compensatingly doped with a P type conductivity modifier. An electrical contact is applied to one surface of the degenerate region forming an ohmic contact with the semiconductor device.

  7. Contact dynamics math model

    NASA Technical Reports Server (NTRS)

    Glaese, John R.; Tobbe, Patrick A.

    1986-01-01

    The Space Station Mechanism Test Bed consists of a hydraulically driven, computer controlled six degree of freedom (DOF) motion system with which docking, berthing, and other mechanisms can be evaluated. Measured contact forces and moments are provided to the simulation host computer to enable representation of orbital contact dynamics. This report describes the development of a generalized math model which represents the relative motion between two rigid orbiting vehicles. The model allows motion in six DOF for each body, with no vehicle size limitation. The rotational and translational equations of motion are derived. The method used to transform the forces and moments from the sensor location to the vehicles' centers of mass is also explained. Two math models of docking mechanisms, a simple translational spring and the Remote Manipulator System end effector, are presented along with simulation results. The translational spring model is used in an attempt to verify the simulation with compensated hardware in the loop results.

  8. /Au Back Contacts

    NASA Astrophysics Data System (ADS)

    Paudel, Naba R.; Compaan, Alvin D.; Yan, Yanfa

    2014-08-01

    We report on the fabrication and characterization of CdTe thin-film solar cells with Cu-free MoO3- x /Au back contacts. CdTe solar cells with sputtered CdTe absorbers of thicknesses from 0.5 to 1.75 μm were fabricated on Pilkington SnO2:F/SnO2-coated soda-lime glasses coated with a 60- to 80-nm sputtered CdS layer. The MoO3- x /Au back contact layers were deposited by thermal evaporation. The incorporation of MoO3- x layer was found to improve the open circuit voltage ( V OC) but reduce the fill factor of the ultrathin CdTe cells. The V OC was found to increase as the CdTe thickness increased.

  9. [Contact allergy to cosmetics].

    PubMed

    Goossens, A; Merckx, L

    1997-12-01

    This article gives the results of contact allergic reactions to cosmetics seen between 1985 and 1990 (462 patients investigated) and between 1991 and 1996 (486 patients investigated). Perfume components remain the most frequently occurring allergens in cosmetics. They are followed by preservative agents, a class within which important shifts have occurred over time (e.g. as with the isothiazolinone mixture). Excipients and certainly emulsifiers (e.g. cocamidopropylbetaine) are potentially not only irritants but also allergens. Among the "active" or category-specific ingredients, oxidative hair dyes, based on paraphenylenediamine and derivatives, and nail care products, based on (meth)acrylates are particularly apt to cause professional dermatoses. Finally, the share of sunscreens as cosmetic allergens remains limited, which may well be because a contact or photocontactallergy is often not recognized since the differential diagnosis with a primary sun intolerance is not always obvious.

  10. Contact dermatitis from propolis.

    PubMed

    Wanscher, B

    1976-04-01

    Two patients with contact dermatitis due to the natural product propolis (bee glue) are reported. They presented perioral eczema and stomatitis which were recalcitrant until propolis was considered as the cause. Patch tests with propolis preparations were positive in both patients, and, furthermore, in the second patient the lesions relapsed after provocation tests. European standard patch test including balsam of Peru were negative. The complexity of propolis, its supposed anti-inflammatory effect due to flavonoids, and the sensitizing agents originating mainly from the poplar trees are discussed together with the cross-sensitization to balsam of Peru. Contact dermatitis due to propolis should be considered in unexplained eczemas, mainly perioral but also in other areas, as propolis preparations are available also as ointments and cosmetic creams.

  11. Contact dermatitis in children

    PubMed Central

    2010-01-01

    Contact dermatitis in pediatric population is a common but (previously) under recognized disease. It is usually divided into the allergic and the irritant forms. The diagnosis is usually obtained with the patch test technique after conducting a thorough medical history and careful physical examination but patch testing in infants may be particularly difficult, and false-positive reactions may occur. This study also provides an overview of the most common allergens in pediatric population and discusses various therapeutic modalities. PMID:20205907

  12. Contact dermatitis in children.

    PubMed

    Rademaker, M; Forsyth, A

    1989-02-01

    125 children under the age of 12 years were patch tested over a period of 7 years. 60 (48%) of the children had 1 or more positive (+ve) reactions, of which 92% (55/60) were considered relevant. The most common allergens were metals (35 + ves), fragrances (24 + ves) and rubber compounds (11 + ves). 40 of the children were also tested for contact urticaria against food additives and fragrances, of whom 20 were positive (benzoic acid 14, cinnamaldehyde 12).

  13. Contact stress sensor

    DOEpatents

    Kotovsky, Jack

    2012-02-07

    A contact stress sensor includes one or more MEMS fabricated sensor elements, where each sensor element of includes a thin non-recessed portion, a recessed portion and a pressure sensitive element adjacent to the recessed portion. An electric circuit is connected to the pressure sensitive element. The circuit includes a thermal compensator and a pressure signal circuit element configured to provide a signal upon movement of the pressure sensitive element.

  14. Contact stress sensor

    DOEpatents

    Kotovsky, Jack

    2014-02-11

    A method for producing a contact stress sensor that includes one or more MEMS fabricated sensor elements, where each sensor element of includes a thin non-recessed portion, a recessed portion and a pressure sensitive element adjacent to the recessed portion. An electric circuit is connected to the pressure sensitive element. The circuit includes a pressure signal circuit element configured to provide a signal upon movement of the pressure sensitive element.

  15. Magnetron Sputtered Gold Contacts on N-gaas

    NASA Technical Reports Server (NTRS)

    Buonaquisti, A. D.; Matson, R. J.; Russell, P. E.; Holloway, P. H.

    1984-01-01

    Direct current planar magnetron sputtering was used to deposit gold Schottky barrier electrical contacts on n-type GaAs of varying doping densities. The electrical character of the contact was determined from current voltage and electron beam induced voltage data. Without reducing the surface concentration of carbon and oxide, the contacts were found to be rectifying. There is evidence that energetic neutral particles reflected from the magnetron target strike the GaAs and cause interfacial damage similar to that observed for ion sputtering. Particle irradiation of the surface during contact deposition is discussed.

  16. Functional modular contact lens

    NASA Astrophysics Data System (ADS)

    Shum, Angela J.; Cowan, Melissa; Lähdesmäki, Ilkka; Lingley, Andrew; Otis, Brian; Parviz, Babak A.

    2009-08-01

    Tear fluid offers a potential route for non-invasive sensing of physiological parameters. Utilization of this potential depends on the ability to manufacture sensors that can be placed on the surface of the eye. A contact lens makes a natural platform for such sensors, but contact lens polymers present a challenge for sensor fabrication. This paper describes a microfabrication process for constructing sensors that can be integrated into the structure of a functional contact lens in the future. To demonstrate the capabilities of the process, an amperometric glucose sensor was fabricated on a polymer substrate. The sensor consists of platinum working and counter electrodes, as well as a region of indium-tin oxide (ITO) for glucose oxidase immobilization. An external silver-silver chloride electrode was used as the reference electrode during the characterization experiments. Sensor operation was validated by hydrogen peroxide measurements in the 10- 20 μM range and glucose measurements in the 0.125-20 mM range.

  17. The Induction of Mental and Contact Contamination

    ERIC Educational Resources Information Center

    Lee, Michelle; Shafran, Roz; Burgess, Charlotte; Carpenter, Jodi; Millard, Emma; Thorpe, Susan

    2013-01-01

    Background: Extreme fear of contamination within obsessive compulsive disorder (OCD) is traditionally conceptualised as a physical phenomenon. More recent research has supported the notion of "mental" contamination (MC) in which people feel contaminated in the absence of physical contact. The current research sought to determine whether feelings…

  18. English in Albania: Contact and Convergence.

    ERIC Educational Resources Information Center

    Dushku, Silvana

    1998-01-01

    Gives an overview of the current status and usage of English in Albania, outlining the sociolinguistic context in which changes in usage have taken place. Evidence is presented of increasing contact areas of English and standard Albanian under the new, post-communist sociopolitical and economic circumstances. Attention is drawn to need for more…

  19. Contact Pressure Level Indication Using Stepped Output Tactile Sensors.

    PubMed

    Choi, Eunsuk; Sul, Onejae; Kim, Juyoung; Kim, Kyumin; Kim, Jong-Seok; Kwon, Dae-Yong; Choi, Byong-Deok; Lee, Seung-Beck

    2016-04-09

    In this article, we report on a novel diaphragm-type tactile pressure sensor that produces stepwise output currents depending on varying low contact pressures. When contact pressures are applied to the stepped output tactile sensor (SOTS), the sensor's suspended diaphragm makes contact with the substrate, which completes a circuit by connecting resistive current paths. Then the contact area, and therefore the number of current paths, would determine the stepped output current produced. This mechanism allows SOTS to have high signal-to-noise ratio (>20 dB) in the 3-500 Hz frequency range at contact pressures below 15 kPa. Moreover, since the sensor's operation does not depend on a material's pressure-dependent electrical properties, the SOTS is able to demonstrate high reproducibility and reliability. By forming a 4 × 4 array of SOTS with a surface bump structure, we demonstrated shear sensing as well as surface (1 × 1 cm²) pressure mapping capabilities.

  20. Molecular mechanisms that control endothelial cell contacts.

    PubMed

    Vestweber, D

    2000-02-01

    Endothelial cell contacts control the permeability of the blood vessel wall. This allows the endothelium to form a barrier for solutes, macromolecules, and leukocytes between the vessel lumen and the interstitial space. Loss of this barrier function in pathophysiological situations can lead to extracellular oedema. The ability of leukocytes to enter tissue at sites of inflammation is dependent on molecular mechanisms that allow leukocytes to adhere to the endothelium and to migrate through the endothelial cell layer and the underlying basal lamina. It is a commonly accepted working hypothesis that inter-endothelial cell contacts are actively opened and closed during this process. Angiogenesis is another important process that requires well-controlled regulation of inter-endothelial cell contacts. The formation of new blood vessels by sprouting from pre-existing vessels depends on the loosening of established endothelial cell contacts and the migration of endothelial cells that form the outgrowing sprouts. This review focuses on the molecular composition of endothelial cell surface proteins and proteins of the cytoskeletal undercoat of the plasma membrane at sites of inter-endothelial cell contacts and discusses the current knowledge about the potential role of such molecules in the regulation of endothelial cell contacts. PMID:10685062

  1. Dual contact pogo pin assembly

    DOEpatents

    Hatch, Stephen McGarry

    2015-01-20

    A contact assembly includes a base and a pair of electrical contacts supported by the base. A first end of the first electrical contact corresponds to a first end of the base and is configured to engage a first external conductive circuit element. A first end of the second electrical contact also corresponds to the first end of the base and is configured to engage a second external conductive circuit element. The first contact and the second contact are electrically isolated from one another and configured to compress when engaging an external connector element. The base includes an aperture positioned on a second end of the base outboard of a second end of the first and second electrical contacts. The aperture presents a narrowing shape with a wide mouth distal the electrical contacts and a narrow internal through-hole proximate the electrical contacts.

  2. Dual contact pogo pin assembly

    DOEpatents

    Hatch, Stephen McGarry

    2016-06-21

    A contact assembly includes a base and a pair of electrical contacts supported by the base. A first end of the first electrical contact corresponds to a first end of the base and is configured to engage a first external conductive circuit element. A first end of the second electrical contact also corresponds to the first end of the base and is configured to engage a second external conductive circuit element. The first contact and the second contact are electrically isolated from one another and configured to compress when engaging an external connector element. The base includes an aperture positioned on a second end of the base outboard of a second end of the first and second electrical contacts. The aperture presents a narrowing shape with a wide mouth distal the electrical contacts and a narrow internal through-hole proximate the electrical contacts.

  3. Is power grasping contact continuous or discrete?

    PubMed Central

    Pataky, Todd C.; Slota, Greg P.; Latash, Mark L.; Zatsiorsky, Vladimir M.

    2014-01-01

    During power grasp the number of local force maxima reflects either the central nervous system’s preferential use of particular hand regions, or anatomical constraints, or both. Previously both biomdal and trimodal force maxima have been hypothesized for power grasp of a cylindrical handle. Here we measure the number of local force maxima, with a resolution of 4.8°, when performing pushing and pulling efforts in the plane perpendicular to the cylinder’s long axis. Twelve participants produced external forces to eight targets. The number of contacts was defined as the number of local maxima exceeding background variance. A minimum of four and a maximum of five discrete contacts were observed in all subjects at the distal phalanges and metacarpal heads. We thus reject previous hypotheses of bimodal or trimodal force control for cylindrical power grasping. Since we presently observed only 4–5 contacts, which is rather low considering the hand’s kinematic flexibility in the flexion plane, we also reject hypotheses of continuous contact, which are inherent to current grasping taxonomy. A modification to current grasping taxonomy is proposed wherein power grasp contains separate branches for continuous and discrete contacts, and where power and precision grasps are distinguished only by grasp manipulability. PMID:23271322

  4. Is power grasping contact continuous or discrete?

    PubMed

    Pataky, Todd C; Slota, Greg P; Latash, Mark L; Zatsiorsky, Vladimir M

    2013-10-01

    During power grasp, the number of local force maxima reflects either the central nervous system's preferential use of particular hand regions, or anatomical constraints, or both. Previously, both bimodal and trimodal force maxima have been hypothesized for power grasp of a cylindrical handle. Here we measure the number of local force maxima, with a resolution of 4.8°, when performing pushing and pulling efforts in the plane perpendicular to the cylinder's long axis. Twelve participants produced external forces to eight targets. The number of contacts was defined as the number of local maxima exceeding background variance. A minimum of four and a maximum of five discrete contacts were observed in all subjects at the distal phalanges and metacarpal heads. We thus reject previous hypotheses of bimodal or trimodal force control for cylindrical power grasping. Since we presently observed only 4-5 contacts, which is rather low considering the hand's kinematic flexibility in the flexion plane, we also reject hypotheses of continuous contact, which are inherent to current grasping taxonomy. A modification to current grasping taxonomy is proposed wherein power grasp contains separate branches for continuous and discrete contacts, and where power and precision grasps are distinguished only by grasp manipulability. PMID:23271322

  5. Adhesion effects in contact interaction of solids

    NASA Astrophysics Data System (ADS)

    Goryacheva, Irina; Makhovskaya, Yulya

    2008-01-01

    An approach to solving problems of the interaction of axisymmetric elastic bodies in the presence of adhesion is developed. The different natures of adhesion, i.e. capillary adhesion, or molecular adhesion described by the Lennard-Jones potential are examined. The effect of additional loading of the interacting bodies outside the contact zone is also investigated. The approach is based on the representation of the pressure outside the contact zone arising from adhesion by a step function. The analytical solution is obtained and is used to analyze the influence of the form of the adhesion interaction potential, of the surface energy of interacting bodies or the films covering the bodies, their shapes (parabolic, higher power exponential function), volume of liquid in the meniscus, density of contact spots, of elastic modulus and the Poisson ratio on the characteristics of the interaction of the bodies in the presence of adhesion. To cite this article: I. Goryacheva, Y. Makhovskaya, C. R. Mecanique 336 (2008).

  6. Microwave sterilization of hydrophilic contact lenses.

    PubMed

    Rohrer, M D; Terry, M A; Bulard, R A; Graves, D C; Taylor, E M

    1986-01-15

    We used standard 2,450-MHz microwave irradiation to achieve sterilization of hydrophilic contact lenses contaminated with a variety of bacterial, fungal, and viral corneal pathogens. A three-dimensional rotisserie was used to overcome the problem of "cold spots" within the microwave oven. The contact lenses became dehydrated in approximately two minutes. Rehydration with normal saline restored their shape and appearance. The time necessary to prohibit all growth of the bacterial and fungal organisms studied ranged from 45 seconds to eight minutes. All viral contaminants were completely inactivated after four minutes of microwave exposure. Refractive properties were unaffected after 101 exposures to microwaves for ten minutes. Slit-lamp examination and scanning electron microscopy disclosed minute particles on the surface of these contact lenses but no damage to the lens matrix from irradiation. PMID:3942177

  7. Atomistic Simulation of Single Asperity Contact

    NASA Astrophysics Data System (ADS)

    Philip; Kromer; Marder, Michael

    2003-03-01

    In the standard (Bowden and Tabor) model of friction, the macroscopic behavior of sliding results from the deformation of microscopic asperities in contact. A recent idea instead extracts macroscopic friction from the aggregate behavior of traveling, self-healing interfacial cracks: certain families of cracks are found to be mathematically forbidden, and the envelope of allowed cracks dictates the familiar Coulomb law of friction. To explore the connection between the new and traditional pictures of friction, we conducted molecular dynamics (MD) simulations of single-asperity contact subjected to an oscillatory sliding force -- a geometry important for the problem of fretting (damage due to small-scale vibratory contact). Our simulations reveal the importance of traveling interface cracks to the dynamics of slip at the interface, and illuminate the dynamics of crack initiation and suppression.

  8. Current Therapeutics, Their Problems, and Sulfur-Containing-Amino-Acid Metabolism as a Novel Target against Infections by “Amitochondriate” Protozoan Parasites

    PubMed Central

    Ali, Vahab; Nozaki, Tomoyoshi

    2007-01-01

    The “amitochondriate” protozoan parasites of humans Entamoeba histolytica, Giardia intestinalis, and Trichomonas vaginalis share many biochemical features, e.g., energy and amino acid metabolism, a spectrum of drugs for their treatment, and the occurrence of drug resistance. These parasites possess metabolic pathways that are divergent from those of their mammalian hosts and are often considered to be good targets for drug development. Sulfur-containing-amino-acid metabolism represents one such divergent metabolic pathway, namely, the cysteine biosynthetic pathway and methionine γ-lyase-mediated catabolism of sulfur-containing amino acids, which are present in T. vaginalis and E. histolytica but absent in G. intestinalis. These pathways are potentially exploitable for development of drugs against amoebiasis and trichomoniasis. For instance, l-trifluoromethionine, which is catalyzed by methionine γ-lyase and produces a toxic product, is effective against T. vaginalis and E. histolytica parasites in vitro and in vivo and may represent a good lead compound. In this review, we summarize the biology of these microaerophilic parasites, their clinical manifestation and epidemiology of disease, chemotherapeutics, the modes of action of representative drugs, and problems related to these drugs, including drug resistance. We further discuss our approach to exploit unique sulfur-containing-amino-acid metabolism, focusing on development of drugs against E. histolytica. PMID:17223627

  9. A Direct analysis of elastic contact using super elements

    NASA Astrophysics Data System (ADS)

    Pedersen, Pauli

    2006-02-01

    Solutions to contact problems are important in mechanical as well as in civil engineering, and even for the most simple problems there is still a need for research results. In the present paper we suggest an alternative finite element procedure and by examples show the need for more knowledge related to the compliance of contact surfaces. The most simple solutions are named Hertz solutions from 1882, and we use some of these solutions for comparison with our finite element results. As a function of the total contact force we find the size of the contact area, the distribution of the contact pressure, and the contact compliance. In models of finite size the compliance depends on the flexibility of the total model, including the boundary condition of the model, and therefore disagreement with the locally based analytical models is expected and found. With computational contact mechanics we can solve more advanced contact problems and treat models that are closer to physical reality. The finite element method is widely used and solutions are obtained by incrementation and/or iteration for these non-linear problems with unknown boundary conditions. Still with these advanced tools the solution is difficult because of extreme sensitivity. Here we present a direct analysis of elastic contact without incrementation and iteration, and the procedure is based on a finite element super element technique. This means that the contacting bodies can be analyzed independently, and are only coupled through a direct analysis with low order super element stiffness matrices. The examples of the present paper are restricted to axisymmetric problems with isotropic, elastic materials and excluding friction. Direct extensions to cases of non-isotropy, including laminates, and to plane and general 3D models are possible.

  10. Contact dermatitis to methylisothiazolinone*

    PubMed Central

    Scherrer, Maria Antonieta Rios; Rocha, Vanessa Barreto; Andrade, Ana Regina Coelho

    2015-01-01

    Methylisothiazolinone (MI) is a preservative found in cosmetic and industrial products. Contact dermatitis caused by either methylchloroisothiazolinone/methylisothiazolinone (MCI/MI or Kathon CG) or MI has shown increasing frequency. The latter is preferably detected through epicutaneous testing with aqueous MI 2000 ppm, which is not included in the Brazilian standard tray. We describe a series of 23 patients tested using it and our standard tray. A case with negative reaction to MCI/MI and positive to MI is emphasized. PMID:26734880

  11. Adhesion in hydrogel contacts

    NASA Astrophysics Data System (ADS)

    Torres, J. R.; Jay, G. D.; Kim, K.-S.; Bothun, G. D.

    2016-05-01

    A generalized thermomechanical model for adhesion was developed to elucidate the mechanisms of dissipation within the viscoelastic bulk of a hyperelastic hydrogel. Results show that in addition to the expected energy release rate of interface formation, as well as the viscous flow dissipation, the bulk composition exhibits dissipation due to phase inhomogeneity morphological changes. The mixing thermodynamics of the matrix and solvent determines the dynamics of the phase inhomogeneities, which can enhance or disrupt adhesion. The model also accounts for the time-dependent behaviour. A parameter is proposed to discern the dominant dissipation mechanism in hydrogel contact detachment.

  12. Adhesive Contact Sweeper

    NASA Technical Reports Server (NTRS)

    Patterson, Jonathan D.

    1993-01-01

    Adhesive contact sweeper removes hair and particles vacuum cleaner leaves behind, without stirring up dust. Also cleans loose rugs. Sweeper holds commercially available spools of inverted adhesive tape. Suitable for use in environments in which air kept free of dust; optics laboratories, computer rooms, and areas inhabited by people allergic to dust. For carpets, best used in tandem with vacuum cleaner; first pass with vacuum cleaner removes coarse particles, and second pass with sweeper extracts fine particles. This practice extends useful life of adhesive spools.

  13. The effect of a temperature-dependent contact parameter on Mars cloud formation

    NASA Astrophysics Data System (ADS)

    Atsuki Urata, Richard; Hollingsworth, Jeffery; Kahre, Melinda

    2015-11-01

    Modeling the current water cycle on Mars is a complex problem that at present remains a scientific challenge. The water cycle is highly coupled to atmospheric temperature, dust, surface ice temperature, atmospheric transport and mixing (i.e. planetary boundary layer (PBL) processes, and radiation, just to name a few. One of the main features of Mars' water cycle is the formation of the aphelion cloud belt. Clouds are formed at altitude (10-40 km) within the subtropics during the aphelion season (Ls=60°-120°). In general the aphelion cloud belt forms at higher altitudes compared to the polar and high-latitude clouds, and therefore at colder temperatures (180 K and below). Laboratory experiments of nucleation under cold temperatures indicate that nucleation becomes more difficult at and below 180 K than expected. This can be modeled by using a temperature-dependent contact parameter, m(T). In this study we use the NASA Ames Mars Global Circulation Model (Mars GCM) to compare the constant contact parameter with the temperature-dependent contact parameterization described by Iraci et al. (2010). The simulations demonstrate that the contact parameter has a significant affect on the opacity of the aphelion clouds, as well as the clouds that form at the edge of the seasonal CO2 ice caps. Both types of clouds tend to form near 180 K, supporting the importance of a temperature-dependent contact parameter.

  14. Theoretical speed and current density limits for different types of electrical brushes

    NASA Astrophysics Data System (ADS)

    Kuhlmann-Wilsdorf, D.

    1984-03-01

    Theoretical performance limits based on the criterion of flash temperature are investigated for monolithic Ag-C brushes, Cu-on-Cu brushes with elastic contact spots, and 'QM' brushes (Quantum Mechanical brushes with ultrathin metal fibers), in which ordinary current conduction is significantly supplemented by electron tunneling peripherally about the contact spots. Equations are developed for the contact spot radii and heat input rates for frictional and electrical heating at the contact spots. Typical data for the flash temperatures are calculated for the high-speed approximation for plastic and elastic contact spots. The low-speed approximation is used for QM brushes. It is concluded that metal fiber and/or QM brushes may represent the best solution to the brush problem for electromagnetic launching.

  15. National directory of space grant contacts

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In this directory of space grant contacts of the NASA Space Grant College and Fellowship Program a listing of participating universities and other institutions are shown from all 50 states and from the District of Columbia and Puerto Rico. These 52 Space Grant State consortia currently consist of 395 institutions of higher learning, 66 industry affiliates, 26 state/local government offices, 40 nonprofit organizations, and 25 other educational entities. This directory is organized alphabetically by state and the contacts, addresses, phone numbers, and internet email addresses (where available) are included.

  16. Contact Lenses in the Laboratory.

    ERIC Educational Resources Information Center

    Kingston, David W.

    1981-01-01

    Summarizes results of a three-item questionnaire returned by 43 Michigan institutions expressing views on wearing contact lenses in chemical laboratories. Questions focused on eye protection, type of protection, and use of contact lenses. (SK)

  17. Scratch resistance of rigid contact lens materials.

    PubMed

    Tranoudis, I; Efron, N

    1996-07-01

    Practitioners have long recognised the importance of determining the extent of scratching on the surface of rigid contact lenses when deciding on lens replacement. Despite this, little research has been undertaken to define this problem. The extent of scratching of rigid contact lens materials was evaluated and this property was related to material oxygen permeability and refractive index. One hundred and forty lenses made from 28 different rigid materials were evaluated in a masked and randomised manner. Scratches were created on the front surface of the lenses using an apparatus that was specifically designed and constructed for this experiment. The extent of scratching was quantitatively evaluated using a computer-based scanning and image analysis system. The oxygen permeability of all materials was measured using the polarographic method. An Atago N3000 hand-held refractometer was used to measure the refractive index of these materials. Three significant correlations were revealed: an inverse relationship (r = -0.813, P < 0.0001) between oxygen permeability and refractive index; a positive relationship (r = 0.511, P < 0.008) between oxygen permeability and the extent of scratching; and an inverse relationship (r = -0.539, P < 0.0058) between refractive index and the extent of scratching. The information generated in this study concerning scratch resistance of rigid contact-lens materials may assist the contact lens industry and contact lens practitioners in developing and prescribing rigid lenses with optimal performance characteristics.

  18. [Systemic contact dermatitis].

    PubMed

    Nowak, Daria; Gomułka, Krzysztof; Dziemieszonek, Paulina; Panaszek, Bernard

    2016-01-01

    Systemic contact dermatitis (SCD) is a skin inflammation occurring in a patient after systemic administration of a hapten, which previously caused an allergic contact skin reaction in the same person. Most frequently, hypersensitivity reactions typical for SCD occur after absorption of haptens with food or inhalation. Haptens occur mainly in the forms of metals and compounds present in natural resins, preservatives, food thickeners, flavorings and medicines. For many years, several studies have been conducted on understanding the pathogenesis of SCD in which both delayed type hypersensitivity (type IV) and immediate type I are observed. Components of the complement system are also suspected to attend there. Helper T cells (Th) (Th1 and Th2), cytotoxic T lymphocytes (Tc), and NK cells play a crucial role in the pathogenesis of SCD. They secrete a number of pro-inflammatory cytokines. In addition, regulatory T cells (Tregs) have an important role. They control and inhibit activity of the immune system during inflammation. Tregs release suppressor cytokines and interact directly with a target cell through presentation of immunosuppressive particles at the cell surface. Diagnostic methods are generally the patch test, oral provocation test, elimination diet and lymphocyte stimulation test. There are many kinds of inflammatory skin reactions caused by systemic haptens' distribution. They are manifested in a variety of clinical phenotypes of the disease. PMID:26943310

  19. Allergic Contact Dermatitis

    PubMed Central

    Nelson, Jenny L.

    2010-01-01

    Epicutaneous patch testing is the gold standard method for the diagnosis of allergic contact dermatitis. Despite this knowledge, many clinical dermatologists do not offer patch testing in their offices or offer testing with only a limited number of allergens. Introduced in 1995, the Thin-Layer Rapid Use Epicutaneous Test originally contained 23 allergens and one control. In 2007, five additional allergens were added. This United States Food and Drug Administration-approved patch testing system made patch testing more convenient, and after its introduction, more dermatologists offered patch testing services. However, the number of allergens in the Thin-Layer Rapid Use Epicutaneous Test remains relatively low. Every two years, the North American Contact Dermatitis Group collects and reports the data from patch testing among its members to a standardized series of allergens. In 2005-2006, the Group used a series of 65 allergens. Of the top 30 allergens reported in 2005-2006, 10 were not included in the Thin-Layer Rapid Use Epicutaneous Test. Knowledge of and testing for additional allergens such as these may increase patch testing yield. PMID:20967194

  20. [Genetics of contact allergy].

    PubMed

    Schnuch, A

    2011-10-01

    The genetics of contact allergy (CA) is still only partly understood, despite decades of research. This might be due to inadequately defined phenotypes used in the past. Therefore we suggested studying an extreme phenotype, namely, polysensitization (sensitization to 3 or more unrelated allergens). Another approach to unravel the genetics of CA has been the study of candidate genes. In this review, we summarize studies on the associations between genetic variation (e.g. SNPs) in certain candidate genes and CA. The following polymorphisms and mutations were studied: (1) filaggrin, (2) N-acetyltransferase (NAT1 and 2), (3) glutathione-S-transferase (GST M and T), (4) manganese superoxide dismutase, (5) angiotensin-converting enzyme (ACE), (6) tumor necrosis factor (TNF), and (7) interleukin-16 (IL16). The polymorphisms of NAT1/2, GST M/T, ACE, TNF, and IL16 were shown to be associated with an increased risk of CA. In one of our studies, the increased risk conferred by the TNF and IL16 polymorphisms was confined to polysensitized individuals. Other relevant candidate genes may be identified by studying diseases related to CA in terms of clinical symptoms, a more general pathology (inflammation) and possibly an overlapping genetic background, such as irritant contact dermatitis. PMID:21904893

  1. Development of perspective methods for modeling 3D currents for coastal systems in connection with environmental problems in South of France as well as South of Russia

    NASA Astrophysics Data System (ADS)

    Alexeenko, Elena; Sukhinov, Alexander; Roux, Bernard; Meule, Samuel; Chistyakov, Alexander

    2010-05-01

    Shallow water reservoirs are complex multi-parameter hydrodynamic systems. The current and the coupled processes occurring in them are spatially three-dimensional and unsteady, and have essentially nonlinear character. Therefore, the use of field experiments to analyse such a systems is extremely labor intensive and costly. Without underestimating the role of field experiments, it should be nevertheless noted that the most optimal in terms of cost and reliability of the results is an approach based on a combination of relatively inexpensive and safe field experiments and mathematical modeling of the processes under study. The present approach has several advantages with respect to the existing models. Three components of velocity vector from the full system of Navier-Stokes equations (and not on the basis of the hydrostatic approximation) and the equation of the surface elevation are calculated. In most hydrodynamic models of shallow water, the third component of the velocity vector is determined from the equations of continuity and the elevation surface level, which introduces significant error in the determination of the component. Calculation of the three components of velocity vector based on the equations of motion is a time-consuming process, so the hydrostatic approximation is used as an initial approximation for calculating the pressure. This approach greatly reduces the computing time and the costs. Also one of the advantages of the present model is an improved parameterization of the vertical turbulent exchange coefficient, on the basis of ADCP measurement data (Acoustic Doppler Current Profiler). In modern numerical models of vertical turbulent exchange, this coefficient often appears as a fitting parameter. Among the numerous approximations of the coefficient of vertical turbulent exchange, the algebraic subgrid model of Belotcerkovskii, which is based on the determination of turbulent flows as multiplications of averaged over time (correlation

  2. High current capacity electrical connector

    DOEpatents

    Bettis, Edward S.; Watts, Harry L.

    1976-01-13

    An electrical connector is provided for coupling high current capacity electrical conductors such as copper busses or the like. The connector is arranged in a "sandwiched" configuration in which a conductor plate contacts the busses along major surfaces thereof clamped between two stainless steel backing plates. The conductor plate is provided with a plurality of contact buttons affixed therein in a spaced array such that the caps of the buttons extend above the conductor plate surface to contact the busses. When clamping bolts provided through openings in the sandwiched arrangement are tightened, Belleville springs provided under the rim of each button cap are compressed and resiliently force the caps into contact with the busses' contacting surfaces to maintain a predetermined electrical contact area provided by the button cap tops. The contact area does not change with changing thermal or mechanical stresses applied to the coupled conductors.

  3. Social work, general practice and evidence-based policy in the collaborative care of older people: current problems and future possibilities.

    PubMed

    Kharicha, Kalpa; Levin, Enid; Iliffe, Steve; Davey, Barbara

    2004-03-01

    While collaborative (or joint) working between social services and primary healthcare continues to rise up the policy agenda, current policy is not based on sound evidence of benefit to either patients or the wider community. Both sets of practitioners report benefits for their own work from adopting new arrangements for collaboration. The underlying assumption behind much of this activity is that a greater degree of integration provides benefits to both users and their carers, a perspective that at times obscures the issue of resource availability, especially in the form of practical community services such as district nursing and home help. At the present time there is insufficient evidence to demonstrate that formal arrangements for collaborative working (CW) are better than those forged informally between committed individuals or teams. Furthermore, arrangements for CW have not hitherto been widely evaluated in systematic studies with a comparative design and focus on outcomes for users and carers rather than on processes. In this paper we propose a number of process measures for future evaluation of CW: (1) study populations must be comparable; (2) details of how services are actually delivered must be obtained and colocation should not be assumed to mean collaboration; (3) care packages in areas of comparable resources should be examined; (4) both destinational outcomes and user-defined evaluations of benefit should be considered; (5) possible disadvantages of integrated care also need to be actively considered; (6) evaluations should include an economic analysis. Those implementing new policies in Primary Care Trusts have, at present, little sound evidence to guide them in their innovative work. However, they should take the opportunity to rigorously test the advantages and disadvantages of collaboration.

  4. Mechanical contact by constraints and split-based preconditioning

    SciTech Connect

    Dmitry Karpeyev; Derek Gaston; Jason Hales; Steven Novascone

    2014-03-01

    An accurate implementation of glued mechanical contact was developed in MOOSE based on its Constraint system. This approach results in a superior convergence of elastic structure problems, in particular in BISON. Adaptation of this technique to frictionless and frictional contact models is under way. Additionally, the improved convergence of elastic problems results from the application of the split-based preconditioners to constraint-based systems. This yields a substantial increase in the robustness of elastic solvers when the number of nodes in contact is increased and/or the mesh is refined.

  5. Contact position sensor using constant contact force control system

    NASA Technical Reports Server (NTRS)

    Sturdevant, Jay (Inventor)

    1995-01-01

    A force control system (50) and method are provided for controlling a position contact sensor (10) so as to produce a constant controlled contact force therewith. The system (50) includes a contact position sensor (10) which has a contact probe (12) for contacting the surface of a target to be measured and an output signal (V.sub.o) for providing a position indication thereof. An actuator (30) is provided for controllably driving the contact position sensor (10) in response to an actuation control signal (I). A controller (52) receives the position indication signal (V.sub.o) and generates in response thereto the actuation control signal (I) so as to provide a substantially constant selective force (F) exerted by the contact probe (12). The actuation drive signal (I) is generated further in response to substantially linear approximation curves based on predetermined force and position data attained from the sensor (10) and the actuator (30).

  6. An Augmented Lagrangian Method for Sliding Contact of Soft Tissue

    PubMed Central

    Guo, Hongqiang; Nickel, Jeffrey C.; Iwasaki, Laura R.; Spilker, Robert L.

    2012-01-01

    Despite the importance of sliding contact in diarthrodial joints, only a limited number of studies have addressed this type of problem, with the result that mechanical behavior of articular cartilage in daily life remains poorly understood. In this paper, a finite element formulation is developed for the sliding contact of biphasic soft tissues. The Augmented Lagrangian method is used to enforce the continuity of contact traction and fluid pressure across the contact interface. The resulting method is implemented in the commercial software COMSOL Multiphysics. The accuracy of the new implementation is verified using an example problem of sliding contact between a rigid, impermeable indenter and a cartilage layer for which analytical solutions have been obtained. The new implementation’s capability to handle a complex loading regime is verified by modeling plowing tests of the temporomandibular joint (TMJ) disc. PMID:22938363

  7. Multidimensional Contact Moduli of Elastically Anisotropic Solids

    SciTech Connect

    Gao, Yanfei; Pharr, George Mathews

    2007-01-01

    Effective moduli of elastically anisotropic solids under normal and tangential contacts are derived using the Stroh formalism and the two dimensional Fourier transform. Each Fourier component corresponds to a plane field in the plane spanned by the surface normal and a wavevector, the solution of which only involves an algebraic eigenvalue problem. Exact solutions are obtained for indenters described by parabolae of revolution, which are found to be a good approximation for arbitrary axisymmetric indenters.

  8. 47 CFR 25.171 - Contact information reporting requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... SERVICES SATELLITE COMMUNICATIONS Applications and Licenses Reporting Requirements for Space Station Operators § 25.171 Contact information reporting requirements. If contact information filed in space station... station's current authorization file. The operator must file the updated information within 10 days....

  9. Intergroup Contact and Ingroup Reappraisal: Examining the Deprovincialization Thesis

    ERIC Educational Resources Information Center

    Verkuyten, Maykel; Thijs, Jochem; Bekhuis, Hidde

    2010-01-01

    According to the deprovincialization thesis, interethnic contact involves a reappraisal and distancing from the ingroup. Contact can broaden one's horizon by acknowledging and recognizing the value of other cultures and thereby putting the taken-for-granted own cultural standards into perspective. The current research uses data from three surveys…

  10. Contact dermatitis in blacks.

    PubMed

    Berardesca, E; Maibach, H I

    1988-07-01

    Black skin is characterized by structural and functional differences such as increased stratum corneum cohesion, melanin content, and stratum corneum layers. These differences seem to make black skin difficult for irritants and light to penetrate, thus explaining the common opinion that skin in blacks is harder and develops contact dermatitis less frequently. The paucity of interpretable epidemiologic data and of clinical and experimental studies does not permit confirmation of this hypothesis, and the few data available are controversial. This article describes the main physiologic differences between black and white barrier function and reviews the literature on irritation, sensitization, and transcutaneous penetration. We found that the data are still too incomplete to generalize on the resistance, or lack thereof, of black skin (versus white skin) to chemical irritation, sensitization, and penetration. PMID:3048818

  11. Update on contact lithotripsy.

    PubMed

    Michel, M S; Köhrmann, K U; Alken, P

    2000-11-01

    Despite the development of extracorporeal shockwave lithotripsy, endoscopic stone removal, with or without intracorporeal lithotripsy, is still an effective minimally invasive alternative for special indications. There is no defined all-purpose lithotripsy procedure for contact lithotripsy. The choice of the lithotripsy procedure for endoscopic stone disintegration depends on a number of different factors, the main one being stone localization. Small calibre, flexible probes (electrohydraulic, pneumatic, laser) are especially appropriate for ureterorenoscopy, but the speed of stone disintegration is a limiting factor. In contrast, large calibre rigid probes (ultrasound) are clearly more effective, but are unsuitable in size for flexible ureterorenoscopy. This indicates that the type and size of the endoscope decisively influences the choice of devices for endoscopic stone disintegration. Additional inhibiting factors are the flexibility or the rigidity of the instrument and the diameter of the working channel. It must be noted that total costs are not only calculated on the purchase of the equipment, but must also cover disposable materials.

  12. Contact dermatitis to fragrances.

    PubMed

    Santucci, B; Cristaudo, A; Cannistraci, C; Picardo, M

    1987-02-01

    2 groups of patients (1200 and 1500 respectively) were patch tested with different concentrations of perfume mix and fragrance raw materials. The study was to evaluate the incidence of contact dermatitis to fragrances in Roma, Italy, and the influence of limited variations in fragrance and perfume mix concentrations on patch test responses. The results showed that a decrease in the perfume mix concentration from 16% to 8% correlated with a decrease in the % of positive patients (from 5.2% to 3.6%). Variations in the concentration of fragrance raw materials did not influence the % of positive reactions in the 2 groups. The perfume mixture at 16% or 8% gave some positive results, without a corresponding reaction to any of the constituents, that were not related to an excited skin syndrome.

  13. Contact dermatitis in blacks.

    PubMed

    Berardesca, E; Maibach, H I

    1988-07-01

    Black skin is characterized by structural and functional differences such as increased stratum corneum cohesion, melanin content, and stratum corneum layers. These differences seem to make black skin difficult for irritants and light to penetrate, thus explaining the common opinion that skin in blacks is harder and develops contact dermatitis less frequently. The paucity of interpretable epidemiologic data and of clinical and experimental studies does not permit confirmation of this hypothesis, and the few data available are controversial. This article describes the main physiologic differences between black and white barrier function and reviews the literature on irritation, sensitization, and transcutaneous penetration. We found that the data are still too incomplete to generalize on the resistance, or lack thereof, of black skin (versus white skin) to chemical irritation, sensitization, and penetration.

  14. Contact dermatitis to Alstroemeria.

    PubMed

    Santucci, B; Picardo, M; Iavarone, C; Trogolo, C

    1985-04-01

    A study was carried out on 50 workers in a floriculture centre to evaluate the incidence of contact dermatitis to Alstroemeria. 3 subjects gave positive reactions to aqueous and ethanolic extracts of cut flowers, stems and leaves. By column chromatography, the allergen was isolated and its chemical structure identified as 6-tuliposide A by proton magnetic resonance and carbon-13 magnetic resonance. Only 6-tuliposide A was isolated from cut flowers, and this gave positive reactions when patch tested at 0.01%; a-methylene-gamma-butyrolactone at 10(-5) (v/v) was positive in the same 3 subjects. Other lactones (gamma-methylene-gamma-butyrolactone, alantolactone, isoalantolactone) were negative at all concentrations used.

  15. Equilibrium contact angle or the most-stable contact angle?

    PubMed

    Montes Ruiz-Cabello, F J; Rodríguez-Valverde, M A; Cabrerizo-Vílchez, M A

    2014-04-01

    It is well-established that the equilibrium contact angle in a thermodynamic framework is an "unattainable" contact angle. Instead, the most-stable contact angle obtained from mechanical stimuli of the system is indeed experimentally accessible. Monitoring the susceptibility of a sessile drop to a mechanical stimulus enables to identify the most stable drop configuration within the practical range of contact angle hysteresis. Two different stimuli may be used with sessile drops: mechanical vibration and tilting. The most stable drop against vibration should reveal the changeless contact angle but against the gravity force, it should reveal the highest resistance to slide down. After the corresponding mechanical stimulus, once the excited drop configuration is examined, the focus will be on the contact angle of the initial drop configuration. This methodology needs to map significantly the static drop configurations with different stable contact angles. The most-stable contact angle, together with the advancing and receding contact angles, completes the description of physically realizable configurations of a solid-liquid system. Since the most-stable contact angle is energetically significant, it may be used in the Wenzel, Cassie or Cassie-Baxter equations accordingly or for the surface energy evaluation.

  16. Reducing contact resistance in graphene devices through contact area patterning.

    PubMed

    Smith, Joshua T; Franklin, Aaron D; Farmer, Damon B; Dimitrakopoulos, Christos D

    2013-04-23

    Performance of graphene electronics is limited by contact resistance associated with the metal-graphene (M-G) interface, where unique transport challenges arise as carriers are injected from a 3D metal into a 2D-graphene sheet. In this work, enhanced carrier injection is experimentally achieved in graphene devices by forming cuts in the graphene within the contact regions. These cuts are oriented normal to the channel and facilitate bonding between the contact metal and carbon atoms at the graphene cut edges, reproducibly maximizing "edge-contacted" injection. Despite the reduction in M-G contact area caused by these cuts, we find that a 32% reduction in contact resistance results in Cu-contacted, two-terminal devices, while a 22% reduction is achieved for top-gated graphene transistors with Pd contacts as compared to conventionally fabricated devices. The crucial role of contact annealing to facilitate this improvement is also elucidated. This simple approach provides a reliable and reproducible means of lowering contact resistance in graphene devices to bolster performance. Importantly, this enhancement requires no additional processing steps.

  17. Point contacts in encapsulated graphene

    SciTech Connect

    Handschin, Clevin; Fülöp, Bálint; Csonka, Szabolcs; Makk, Péter; Blanter, Sofya; Weiss, Markus; Schönenberger, Christian; Watanabe, Kenji; Taniguchi, Takashi

    2015-11-02

    We present a method to establish inner point contacts with dimensions as small as 100 nm on hexagonal boron nitride (hBN) encapsulated graphene heterostructures by pre-patterning the top-hBN in a separate step prior to dry-stacking. 2- and 4-terminal field effect measurements between different lead combinations are in qualitative agreement with an electrostatic model assuming point-like contacts. The measured contact resistances are 0.5–1.5 kΩ per contact, which is quite low for such small contacts. By applying a perpendicular magnetic field, an insulating behaviour in the quantum Hall regime was observed, as expected for inner contacts. The fabricated contacts are compatible with high mobility graphene structures and open up the field for the realization of several electron optical proposals.

  18. A Prototype Antifungal Contact Lens

    PubMed Central

    Ciolino, Joseph B.; Hudson, Sarah P.; Mobbs, Ashley N.; Hoare, Todd R.; Iwata, Naomi G.; Fink, Gerald R.

    2011-01-01

    Purpose. To design a contact lens to treat and prevent fungal ocular infections. Methods. Curved contact lenses were created by encapsulating econazole-impregnated poly(lactic-co-glycolic) acid (PLGA) films in poly(hydroxyethyl methacrylate) (pHEMA) by ultraviolet photopolymerization. Release studies were conducted in phosphate-buffered saline at 37°C with continuous shaking. The contact lenses and their release media were tested in an antifungal assay against Candida albicans. Cross sections of the pre- and postrelease contact lenses were characterized by scanning electron microscopy and by Raman spectroscopy. Results. Econazole-eluting contact lenses provided extended antifungal activity against Candida albicans fungi. Fungicidal activity varied in duration and effectiveness depending on the mass of the econazole-PLGA film encapsulated in the contact lens. Conclusions. An econazole-eluting contact lens could be used as a treatment for fungal ocular infections. PMID:21527380

  19. Dynamics of the Molten Contact Line

    NASA Technical Reports Server (NTRS)

    Sonin, Ain A.; Duthaler, Gregg; Liu, Michael; Torresola, Javier; Qiu, Taiqing

    1999-01-01

    amorphous silicon dioxide chips. Each chip has 32 sensors distributed on its surface in arrays. The time response is better than 10 ms. At the time of writing, sensor calibration is in progress. Results on thermal transients during contact line passage will be discussed at the conference. While we expect that the data will provide information on the near-contact-line heat transfer process, we also foresee possible problems. First, the spatial resolution of the sensors may be insufficient to resolve the near-contact-line region. Second, the sensors protrude about 0.5 microns above the substrate surface, and may affect the contact line motion. Third, a sensor's temperature history depends on both the heat flux distribution into it from the fusion front and the thermal properties of the substrate below it and the solidified melt between it and the fusion front. The heat flux distribution in the contact line region must therefore be unfolded from computations of the overall system's transient thermal response.

  20. Behavior of vacuum arcs between spiral contacts with reduced spacing

    NASA Astrophysics Data System (ADS)

    Schulman, M. B.

    1994-05-01

    The use of reduced gaps in applications of high-current vacuum arc devices presents a number of interesting challenges. Specifically, standard contact designs have been developed over several decades to achieve controlled motion of high-current ac arcs in vacuum interrupters. For medium-voltage applications, the optimal maximum contact gap can typically range from about 6 mm to about 2 cm. However, the influence of the contact design may be gap dependent, so additional research may be appropriate if the contacts are to be used at smaller gaps. For example, the current through spiral contacts produces a magnetic field perpendicular to the arc column, but this will force the arc to move outward and run along the periphery of the petals only if a threshold separation is achieved. In this investigation, a framing camera was used to record the appearance and motion of drawn vacuum arcs between spiral-petal contacts with final gaps of 2 to 3 mm. After the rupture of the molten bridge, a high-pressure arc column formed and expanded across the width of the spiral arm. At the reduced gap, an intense anode spot formed if the peak current exceeded approximately 15 kA. Compared to results previously obtained at larger gaps, the arc motion was greatly reduced, and severe contact damage was observed at lower currents.

  1. Low-frequency noise in transport through quantum point contacts

    SciTech Connect

    Li, Y.P.; Tsui, D.C.; Heremans, J.J.; Simmons, J.A. ); Weimann, G.W. )

    1990-08-20

    We report the noise characteristics of quantum point contacts between 100 Hz and 100 kHz at 4.2 K. The noise consists of a 1/{ital f} component on top of a white background. The 1/{ital f} noise increases as the contact width decreases and shows peaks between the quantized resistance plateaus. The white noise background increases with current but is much lower than the full shot noise level, suggesting that shot noise is not generated in an ideal quantum point contact, where the electrons do not suffer backscattering as they enter and traverse the contact.

  2. Raman signatures of TNT in contact with sand particles

    NASA Astrophysics Data System (ADS)

    Herrera-Sandoval, Gloria M.; Ballesteros, Luz M.; Mina, Nairmen; Briano, Julio; Castro, Miguel E.; Hernandez-Rivera, Samuel P.

    2005-06-01

    Landmines have become a problem and a daily risk in approximately 70 countries. There exists a broad variety of types of mines in which trinitrotoluene (TNT) is mostly used as the main explosive charge. TNT has a number of specific properties that make it a nearly ideal explosive for military applications. There are several methods currently used to detect buried landmines. The goal of this work is develop new methods for detecting TNT in contact with soil and sand. Raman microscopy is used to provide information about identity, composition, molecular orientation or crystal formation in very small samples or small heterogeneities in large samples. The possible interactions of the energetic material with sand particles have been studied by quantitative vibrational spectroscopy. Ambient conditions that may affect the spectroscopic signature of the explosive in contact with soil were also studied. Among the parameters investigated were: Sand-TNT mass ratio, temperature, pH of soil, incidence of UV light and water content. The characteristic bands of TNT are not significantly shifted, but rather appear constant with respect of the characteristic band of Si-O in sand (~464 cm-1).

  3. Modeling the emergence of contact languages.

    PubMed

    Tria, Francesca; Servedio, Vito D P; Mufwene, Salikoko S; Loreto, Vittorio

    2015-01-01

    Contact languages are born out of the non-trivial interaction of two (or more) parent languages. Nowadays, the enhanced possibility of mobility and communication allows for a strong mixing of languages and cultures, thus raising the issue of whether there are any pure languages or cultures that are unaffected by contact with others. As with bacteria or viruses in biological evolution, the evolution of languages is marked by horizontal transmission; but to date no reliable quantitative tools to investigate these phenomena have been available. An interesting and well documented example of contact language is the emergence of creole languages, which originated in the contacts of European colonists and slaves during the 17th and 18th centuries in exogenous plantation colonies of especially the Atlantic and Indian Ocean. Here, we focus on the emergence of creole languages to demonstrate a dynamical process that mimics the process of creole formation in American and Caribbean plantation ecologies. Inspired by the Naming Game (NG), our modeling scheme incorporates demographic information about the colonial population in the framework of a non-trivial interaction network including three populations: Europeans, Mulattos/Creoles, and Bozal slaves. We show how this sole information makes it possible to discriminate territories that produced modern creoles from those that did not, with a surprising accuracy. The generality of our approach provides valuable insights for further studies on the emergence of languages in contact ecologies as well as to test specific hypotheses about the peopling and the population structures of the relevant territories. We submit that these tools could be relevant to addressing problems related to contact phenomena in many cultural domains: e.g., emergence of dialects, language competition and hybridization, globalization phenomena.

  4. Modeling the Emergence of Contact Languages

    PubMed Central

    Tria, Francesca; Servedio, Vito D.P.; Mufwene, Salikoko S.; Loreto, Vittorio

    2015-01-01

    Contact languages are born out of the non-trivial interaction of two (or more) parent languages. Nowadays, the enhanced possibility of mobility and communication allows for a strong mixing of languages and cultures, thus raising the issue of whether there are any pure languages or cultures that are unaffected by contact with others. As with bacteria or viruses in biological evolution, the evolution of languages is marked by horizontal transmission; but to date no reliable quantitative tools to investigate these phenomena have been available. An interesting and well documented example of contact language is the emergence of creole languages, which originated in the contacts of European colonists and slaves during the 17th and 18th centuries in exogenous plantation colonies of especially the Atlantic and Indian Ocean. Here, we focus on the emergence of creole languages to demonstrate a dynamical process that mimics the process of creole formation in American and Caribbean plantation ecologies. Inspired by the Naming Game (NG), our modeling scheme incorporates demographic information about the colonial population in the framework of a non-trivial interaction network including three populations: Europeans, Mulattos/Creoles, and Bozal slaves. We show how this sole information makes it possible to discriminate territories that produced modern creoles from those that did not, with a surprising accuracy. The generality of our approach provides valuable insights for further studies on the emergence of languages in contact ecologies as well as to test specific hypotheses about the peopling and the population structures of the relevant territories. We submit that these tools could be relevant to addressing problems related to contact phenomena in many cultural domains: e.g., emergence of dialects, language competition and hybridization, globalization phenomena. PMID:25875371

  5. Modeling the emergence of contact languages.

    PubMed

    Tria, Francesca; Servedio, Vito D P; Mufwene, Salikoko S; Loreto, Vittorio

    2015-01-01

    Contact languages are born out of the non-trivial interaction of two (or more) parent languages. Nowadays, the enhanced possibility of mobility and communication allows for a strong mixing of languages and cultures, thus raising the issue of whether there are any pure languages or cultures that are unaffected by contact with others. As with bacteria or viruses in biological evolution, the evolution of languages is marked by horizontal transmission; but to date no reliable quantitative tools to investigate these phenomena have been available. An interesting and well documented example of contact language is the emergence of creole languages, which originated in the contacts of European colonists and slaves during the 17th and 18th centuries in exogenous plantation colonies of especially the Atlantic and Indian Ocean. Here, we focus on the emergence of creole languages to demonstrate a dynamical process that mimics the process of creole formation in American and Caribbean plantation ecologies. Inspired by the Naming Game (NG), our modeling scheme incorporates demographic information about the colonial population in the framework of a non-trivial interaction network including three populations: Europeans, Mulattos/Creoles, and Bozal slaves. We show how this sole information makes it possible to discriminate territories that produced modern creoles from those that did not, with a surprising accuracy. The generality of our approach provides valuable insights for further studies on the emergence of languages in contact ecologies as well as to test specific hypotheses about the peopling and the population structures of the relevant territories. We submit that these tools could be relevant to addressing problems related to contact phenomena in many cultural domains: e.g., emergence of dialects, language competition and hybridization, globalization phenomena. PMID:25875371

  6. Analysis of Resistance and Surface Recombination Velocities by Contact Coverage for Optimizing Electrical Loss in c-Si Local Back Contact.

    PubMed

    Park, Cheolmin; Ryu, Kyungyul; Balaji, Nagarajan; Lee, Seunghwan; Kim, Jungmo; Ju, Minkyu; Lee, Youn-Jung; Lee, Hoongjoo; Yi, Junsin

    2015-06-01

    Recently, the importance of solar cell research has emerged due to emerging social issues such as environmental pollution problems and rising oil prices. Accordingly, each company is studying to make solar cell of high efficiency. In order to fabricate high-efficiency solar cells, the two major techniques have to be applied on the rear. One is complete passivation of the surface using a thermal oxide and the other one is the part that comes in contact with the electrode doped partially LBSF (Local BSF) formation. In this paper, LBC technology which is usually applied for high efficiency crystalline silicon solar cell, applied to mass productive solar cell to achieve high open circuit voltage and short circuit current with low surface recombination from rear side. Thermal SiO2/SiN(x) double layer which has superior thermal stability is formed on rear surface as passivation layer, then 1% of the whole rear surface area is locally contacted with aluminum. Finally, the cell has been fired at high temperature and the cell process has complete. The fabricated LBC cells conversion efficiency was 18.0% with 625 mV of open-circuit voltage (V(oc)), 37.58 mA/cm2 of current density (J(sc)), 76.3% of fillfactor (FF) at 5% contact coverage, respectively.

  7. Analysis of composite material interface crack face contact and friction effects using a new node-pairs contact algorithm

    NASA Astrophysics Data System (ADS)

    Zhong, Zhi-Peng; He, Yu-Bo; Wan, Shui

    2014-06-01

    A new node-pairs contact algorithm is proposed to deal with a composite material or bi-material interface crack face contact and friction problem (e.g., resistant coating and thermal barrier coatings) subjected to complicated load conditions. To decrease the calculation scale and calculation errors, the local Lagrange multipliers are solved only on a pair of contact nodes using the Jacobi iteration method, and the constraint modification of the tangential multipliers are required. After the calculation of the present node-pairs Lagrange multiplier, it is turned to next contact node-pairs until all node-pairs have finished. Compared with an ordinary contact algorithm, the new local node-pairs contact algorithm is allowed a more precise element on the contact face without the stiffness matrix singularity. The stress intensity factors (SIFs) and the contact region of an infinite plate central crack are calculated and show good agreement with those in the literature. The contact zone near the crack tip as well as its influence on singularity of stress fields are studied. Furthermore, the frictional contacts are also considered and found to have a significant influence on the SIFs. The normalized mode-II stress intensity factors K̂II for the friction coefficient decrease by 16% when f changes from 1 to 0.

  8. Hysteresis during contact angles measurement.

    PubMed

    Diaz, M Elena; Fuentes, Javier; Cerro, Ramon L; Savage, Michael D

    2010-03-15

    A theory, based on the presence of an adsorbed film in the vicinity of the triple contact line, provides a molecular interpretation of intrinsic hysteresis during the measurement of static contact angles. Static contact angles are measured by placing a sessile drop on top of a flat solid surface. If the solid surface has not been previously in contact with a vapor phase saturated with the molecules of the liquid phase, the solid surface is free of adsorbed liquid molecules. In the absence of an adsorbed film, molecular forces configure an advancing contact angle larger than the static contact angle. After some time, due to an evaporation/adsorption process, the interface of the drop coexists with an adsorbed film of liquid molecules as part of the equilibrium configuration, denoted as the static contact angle. This equilibrium configuration is metastable because the droplet has a larger vapor pressure than the surrounding flat film. As the drop evaporates, the vapor/liquid interface contracts and the apparent contact line moves towards the center of the drop. During this process, the film left behind is thicker than the adsorbed film and molecular attraction results in a receding contact angle, smaller than the equilibrium contact angle.

  9. The modular approach enables a fully ab initio simulation of the contacts between 3D and 2D materials

    NASA Astrophysics Data System (ADS)

    Fediai, Artem; Ryndyk, Dmitry A.; Cuniberti, Gianaurelio

    2016-10-01

    Up to now, the electrical properties of the contacts between 3D metals and 2D materials have never been computed at a fully ab initio level due to the huge number of atomic orbitals involved in a current path from an electrode to a pristine 2D material. As a result, there are still numerous open questions and controversial theories on the electrical properties of systems with 3D/2D interfaces—for example, the current path and the contact length scalability. Our work provides a first-principles solution to this long-standing problem with the use of the modular approach, a method which rigorously combines a Green function formalism with the density functional theory (DFT) for this particular contact type. The modular approach is a general approach valid for any 3D/2D contact. As an example, we apply it to the most investigated among 3D/2D contacts—metal/graphene contacts—and show its abilities and consistency by comparison with existing experimental data. As it is applicable to any 3D/2D interface, the modular approach allows the engineering of 3D/2D contacts with the pre-defined electrical properties.

  10. Bernoulli effect and contact potential difference in superconductors

    SciTech Connect

    Omel'yanchuk, A.N.; Beloborod'ko, S.I.

    1983-10-01

    An expression is derived for the Bernoulli potential that arises in superconductors with an inhomogeneous current distribution. The expression is valid for arbitrary temperatures and superfluid velocities. In the superconductor--dielectric--superconductor system we consider the Bernoulli effect, which manifests itself in a contact potential difference between the superconductors. The potential difference is determined by the currents flowing through one plate of the contact and can be measured with a voltmeter in the quasi-stationary regime.

  11. Sliding contact fracture of dental ceramics: Principles and validation.

    PubMed

    Ren, Linlin; Zhang, Yu

    2014-07-01

    Ceramic prostheses are subject to sliding contact under normal and tangential loads. Accurate prediction of the onset of fracture at two contacting surfaces holds the key to greater long-term performance of these prostheses. In this study, building on stress analysis of Hertzian contact and considering fracture criteria for linear elastic materials, a constitutive fracture mechanics relation was developed to incorporate the critical fracture load with the contact geometry, coefficient of friction and material fracture toughness. Critical loads necessary to cause fracture under a sliding indenter were calculated from the constitutive equation, and compared with the loads predicted from elastic stress analysis in conjunction with measured critical load for frictionless normal contact-a semi-empirical approach. The major predictions of the models were calibrated with experimentally determined critical loads of current and future dental ceramics after contact with a rigid spherical slider. Experimental results conform with the trends predicted by the models.

  12. Atomically Thin Ohmic Edge Contacts Between Two-Dimensional Materials.

    PubMed

    Guimarães, Marcos H D; Gao, Hui; Han, Yimo; Kang, Kibum; Xie, Saien; Kim, Cheol-Joo; Muller, David A; Ralph, Daniel C; Park, Jiwoong

    2016-06-28

    With the decrease of the dimensions of electronic devices, the role played by electrical contacts is ever increasing, eventually coming to dominate the overall device volume and total resistance. This is especially problematic for monolayers of semiconducting transition-metal dichalcogenides (TMDs), which are promising candidates for atomically thin electronics. Ideal electrical contacts to them would require the use of similarly thin electrode materials while maintaining low contact resistances. Here we report a scalable method to fabricate ohmic graphene edge contacts to two representative monolayer TMDs, MoS2 and WS2. The graphene and TMD layer are laterally connected with wafer-scale homogeneity, no observable overlap or gap, and a low average contact resistance of 30 kΩ·μm. The resulting graphene edge contacts show linear current-voltage (I-V) characteristics at room temperature, with ohmic behavior maintained down to liquid helium temperatures.

  13. Noise-activated dissociation of soft elastic contacts.

    PubMed

    Chaudhury, M K; Goohpattader, P S

    2012-12-01

    Adhesive forces are capable of deforming a soft elastic object when it comes in contact with a flat rigid substrate. The contact is in stable equilibrium if the total energy of the system arising from the elastic and surface forces exhibits a minimum at a zero or at a slightly negative load. However, as the system is continually unloaded, the energy barrier decreases and it eventually disappears, thus leading to a ballistic separation of the contact. While this type of contact splitting has received wide recognition, what has not been much appreciated with these types of soft adhesion problems is that rupture of a contact can also occur at any finite sub critical load in the presence of a noise. The soft contact problems are unique in that the noise can be athermal, whereas the metastable and stable states of the thermodynamic potential can arise from the competition of the elastic and the interfacial energies of the system. Analysis based on Kramers' theory and simulations based on Langevin dynamics show that the contact rupture dynamics is amenable to an Eyring's form of a force and noise-induced escape of a particle from a potential well that is generic to various types of colloidal and macromolecular processes. These ideas are useful in understanding the results of a recent experiment involving the noise-activated rolling dynamics of a rigid sphere on a surface, where it is pinned by soft micro-fibrillar contacts.

  14. Contact pressure-aided spectroscopy.

    PubMed

    Bregar, Maksimilijan; Bürmen, Miran; Aljancic, Uroš; Cugmas, Blaž; Pernuš, Franjo; Likar, Boštjan

    2014-02-01

    Contact pressure induced by manually operated fiber optic probes can significantly affect the optical properties of the studied tissue. If the contact pressure and the changes in optical properties are measured properly, then the complementary information can be used to obtain additional insight into the tissue physiology. However, as reliable assessment of the contact pressure in the existing diffuse reflectance setups is difficult, the impact of contact pressure is usually neglected or considered as a source of errors. We introduce a measurement system for controlled application of contact pressure and for the acquisition of diffuse reflectance spectra, which is suitable for in vivo studies and for overcoming the limitations of the existing measurement setups. A spectral-contact-pressure plane is proposed to present the combined information, highlighting the unique tissue response to the applied pressure.

  15. A tire contact solution technique

    NASA Technical Reports Server (NTRS)

    Tielking, J. T.

    1983-01-01

    An efficient method for calculating the contact boundary and interfacial pressure distribution was developed. This solution technique utilizes the discrete Fourier transform to establish an influence coefficient matrix for the portion of the pressurized tire surface that may be in the contact region. This matrix is used in a linear algebra algorithm to determine the contact boundary and the array of forces within the boundary that are necessary to hold the tire in equilibrium against a specified contact surface. The algorithm also determines the normal and tangential displacements of those points on the tire surface that are included in the influence coefficient matrix. Displacements within and outside the contact region are calculated. The solution technique is implemented with a finite-element tire model that is based on orthotropic, nonlinear shell of revolution elements which can respond to nonaxisymmetric loads. A sample contact solution is presented.

  16. [Short bowel syndrome. Still a current problem].

    PubMed

    Calomino, N; Malerba, M; Oliva, G; Palasciano, G; Cappelli, A; Salvestrini, F; Tanzini, G

    1997-01-01

    In the last year the Authors operated two patients presenting with a clinical feature of intestinal infarct. A wide intestinal resection was performed and patients had a residual tract of 40 cm and 50 cm of bowel respectively, later manifesting as short bowel syndrome. It was not possible during the operation to preserve the Baubin valve in one case, in the other one the value had been sacrificed during a previous operation for right colonic malignancy. In the postoperative period, patients were temporarily transferred to the intensive care unit, returning in the surgery ward after few days, and counting total parenteral nutrition with progressive decreasing mixture in calories. Contemporarly enteral nutrition was started slowly increasing the quantity of water, calories and azote administration. In a second time oral diet was started up to completely weaning parenteral and enteral nutrition. At the present patients are enlisted in quarterly follow-up, completely stabilized, and independent from artificial nutrition with a good quality of life. Furthermore a saving of sanitary costs was obtained. PMID:9296596

  17. CURRENT TECHNICAL PROBLEMS IN EMERGY ANALYSIS

    EPA Science Inventory

    : Emergy Analysis has been a rapidly evolving assessment methodology for the past 30 years. This process of development was primarily driven by the inquiring mind and ceaseless activity of its founder, H.T. Odum, his students, and colleagues. Historically, as new kinds of proble...

  18. [Some current problems in drafting laws].

    PubMed

    1979-01-01

    It has become apparent that the authority of the various organs to draft laws must be firmly established in China. In recent years prevalent local laws have in many cases infringed on the people's democratic rights and interests. For example, in some villages local authorities popularizing birth control have dispatched militia teams to households in which couples did not practice birth control to make propaganda, but also to exercise control over their food, drinking water, and work points. Such behavior is not justified and causes dissatisfaction among the people. The basic principle of the people's court is that all citizens are equal under the law regardless of nationality, sex, race, occupation, and social background. This applies to all those who have not been deprived of citizenship, whether they belong to the masses or to the cadres.

  19. [Interventional radiology: current problems and new directions].

    PubMed

    Santos Martín, E; Crespo Vallejo, E

    2014-01-01

    In recent years, vascular and interventional radiology has become one of the fastest growing diagnostic and therapeutic specialties. This growth has been based on a fundamental concept: performing minimally invasive procedures under imaging guidance. This attractive combination has led to the interest of professionals from other clinical specialties outside radiology in performing this type of intervention. The future of vascular and interventional radiology, although uncertain, must be linked to clinical practice and multidisciplinary teamwork.

  20. Some current problems in oxidation kinetics

    NASA Technical Reports Server (NTRS)

    Benson, S. W.

    1972-01-01

    Experimental data in low temperature and high temperature oxidations are examined from the point of view of reported quantitative inconsistencies. Activation energies for tBuO2 metathesis reactions with alkanes appear to be 7 kcal/mole higher than for comparable reactions of HO2. Related isomerization reactions are examined in the light of these differences without reaching any simple conclusions. The Russell mechanism for a 6-membered, cyclic, transition state for termination of primary and secondary alkyl peroxy radicals is shown to be either inconsistent with thermochemical data, or else unique to solution reactions. Addition reactions of O3 with olefins and acetylenes are shown thermochemically to have the possibility of following concerted and biradical pathways, respectively. Recent data showing strong inhibition by PbO coated surfaces of both oxidation and pyrolysis of i-C4H10 are examined in terms of mechanism.

  1. Numerical Simulation of Dynamic Contact Angles and Contact Lines in Multiphase Flows using Level Set Method

    NASA Astrophysics Data System (ADS)

    Pendota, Premchand

    Many physical phenomena and industrial applications involve multiphase fluid flows and hence it is of high importance to be able to simulate various aspects of these flows accurately. The Dynamic Contact Angles (DCA) and the contact lines at the wall boundaries are a couple of such important aspects. In the past few decades, many mathematical models were developed for predicting the contact angles of the inter-face with the wall boundary under various flow conditions. These models are used to incorporate the physics of DCA and contact line motion in numerical simulations using various interface capturing/tracking techniques. In the current thesis, a simple approach to incorporate the static and dynamic contact angle boundary conditions using the level set method is developed and implemented in multiphase CFD codes, LIT (Level set Interface Tracking) (Herrmann (2008)) and NGA (flow solver) (Desjardins et al (2008)). Various DCA models and associated boundary conditions are reviewed. In addition, numerical aspects such as the occurrence of a stress singularity at the contact lines and grid convergence of macroscopic interface shape are dealt with in the context of the level set approach.

  2. Contact dermatitis to homomenthyl salicylate.

    PubMed

    Rietschel, R L; Lewis, C W

    1978-03-01

    Two patients with follicular dermatitis were found to have a contact sensitivity to homomenthyl salicylate, a sunscreening chemical present in a commercially available suntan lotion. One patient did not use the product, but her boyfriend did, and contact between the two individuals resulted in a follicular dermatitis developing in her. A second patient with contact dermatitis to homomenthyl salicylate also had a follicular eruption. Both patients appear to represent true allergic sensitivities.

  3. Point contact silicon solar cells

    NASA Technical Reports Server (NTRS)

    Swanson, Richard M.

    1987-01-01

    A new type of silicon solar cell has been developed. It is called the point-contact cell because the metal semiconductor contacts are restricted to an array of small points on the back of the cell. The point contact cell has recently demonstrated 22 percent conversion efficiency at one sun and 27.5 percent at 100 suns under an AM1.5 spectrum.

  4. Method for forming metal contacts

    DOEpatents

    Reddington, Erik; Sutter, Thomas C; Bu, Lujia; Cannon, Alexandra; Habas, Susan E; Curtis, Calvin J; Miedaner, Alexander; Ginley, David S; Van Hest, Marinus Franciscus Antonius Maria

    2013-09-17

    Methods of forming metal contacts with metal inks in the manufacture of photovoltaic devices are disclosed. The metal inks are selectively deposited on semiconductor coatings by inkjet and aerosol apparatus. The composite is heated to selective temperatures where the metal inks burn through the coating to form an electrical contact with the semiconductor. Metal layers are then deposited on the electrical contacts by light induced or light assisted plating.

  5. Process window variation comparison between NTD and PTD for various contact type

    NASA Astrophysics Data System (ADS)

    Kim, Doyoun; Yune, Hyoungsoon; Park, Daejin; Jeong, Joohong; Moon, Woosung; Kim, Mingu; Oh, Seyoung; Park, Chanha; Yang, Hyunjo

    2016-03-01

    As technology node has been shrinking for bit growth, various technologies have been developed for high productivity. Nevertheless, lithography technology is close to its limit. In order to overcome these limits, EUV(Extreme Ultraviolet Lithography) and DSA(Directed Self-Assembly) are being developed, but there still exists problems for mass production. Currently, all lithography technology developments focus on solving the problems related to fine patterning and widening process window. One of the technologies is NTD(Negative Tone Development) which uses inverse development compared to PTD(Positive Tone Development). The exposed area is eliminated by positive developer in PTD, whereas the exposed area is remained in NTD. It is well known that NTD has better characteristics compared to PTD in terms of DOF(Depth of Focus) margin, MEEF(Mask Error Enhancement Factor), and LER(Line End Roughness) for both small contact holes and isolated spaces [1]. Contact hole patterning is especially more difficult than space patterning because of the lower image contrast and smaller process window [2]. Thus, we have focused on the trend of both NTD and PTD contact hole patterns in various environments. We have analyzed optical performance of both NTD and PTD according to size and pitch by SMO(Source Mask Optimization) software. Moreover, the simulation result of NTD process was compared with the NTD wafer level performance and the process window variation of NTD was characterized through both results. This result will be a good guideline to avoid DoF loss when using NTD process for contact layers with various contact types. In this paper, we studied the impact of different sources on various combinations of pattern sizes and pitches while estimating DOF trends aside from source and pattern types.

  6. Balance Problems

    MedlinePlus

    ... often, it could be a sign of a balance problem. Balance problems can make you feel unsteady or as ... fall-related injuries, such as hip fracture. Some balance problems are due to problems in the inner ...

  7. Ion Implanted Passivated Contacts for Interdigitated Back Contacted Solar Cells

    SciTech Connect

    Young, David L.; Nemeth, William; LaSalvia, Vincenzo; Reedy, Robert; Bateman, Nicholas; Stradins, Pauls

    2015-06-14

    We describe work towards an interdigitated back contacted (IBC) solar cell utilizing ion implanted, passivated contacts. Formation of electron and hole passivated contacts to n-type CZ wafers using tunneling SiO2 and ion implanted amorphous silicon (a-Si) are described. P and B were ion implanted into intrinsic amorphous Si films at several doses and energies. A series of post-implant anneals showed that the passivation quality improved with increasing annealing temperatures up to 900 degrees C. The recombination parameter, Jo, as measured by a Sinton lifetime tester, was Jo ~ 14 fA/cm2 for Si:P, and Jo ~ 56 fA/cm2 for Si:B contacts. The contact resistivity for the passivated contacts, as measured by TLM patterns, was 14 milliohm-cm2 for the n-type contact and 0.6 milliohm-cm2 for the p-type contact. These Jo and pcontact values are encouraging for forming IBC cells using ion implantation to spatially define dopants.

  8. Contact Disturbances, Self-Esteem and Life Satisfaction of University Students: A Structural Equation Modelling Study

    ERIC Educational Resources Information Center

    Tagay, Özlem

    2015-01-01

    Problem Statement: A literature analysis revealed that contact disturbances, self-esteem and life satisfaction have been examined in different studies separately. In particular, the researchers observed that the studies conducted on Gestalt contact disturbances are limited in number. In this study, the variables of contact disturbances,…

  9. Evaluation of Nominal Contact Area and Contact Pressure Distribution in a Steel-Steel Interface by Means of Ultrasonic Techniques

    NASA Astrophysics Data System (ADS)

    Aymerich, Francesco; Pau, Massimiliano; Ginesu, Francesco

    Analysis of contact interfaces represents one of the most critical engineering problems and involves a huge number of practical applications such as roller bearings, tooth gears, wheel-rail interaction, electrical and thermal couplings, biomechanics etc. While theoretical and numerical approaches to the problem have been extensively studied over the years, only a few experimental techniques have been devised either to validate analytical results, or to infer information non invasively about the state of contact. From the late 1950s onwards, when a relationship was discovered between the amount of energy reflected or transmitted through the contact region and the characteristics of contact, researchers have been employing ultrasonic waves to inspect contact interfaces. Since then, many efforts have been directed towards improving the experimental technique and enhancing the theoretical understanding of ultrasonic waves propagation over an incomplete contact interface. In the light of these considerations, the application of a simple ‘pulse-echo' technique able to investigate the elastoplastic contact of a steel sphere-plate system is proposed in this paper. The main purpose of the analysis is to assess the reliability of the ultrasonic method as a useful tool for assessing a number of contact parameters such as size and shape of contact area, distribution of contact pressure and so on. Experimental data were compared with numerical results obtained using a Finite Element Model (FEM) code. Ultrasonic reflection data were in good agreement with calculated values, thus confirming the effectiveness of the ultrasonic technique as a fast, reliable and non-invasive method in evaluating contact parameters in loaded metallic interfaces.

  10. Interactive contacts resolution using smooth surface representation.

    PubMed

    Dequidt, Jérémie; Lenoir, Julien; Cotin, Stéphane

    2007-01-01

    Accurately describing interactions between medical devices and anatomical structures, or between anatomical structures themselves, is an essential step towards the adoption of computer-based medical simulation as an alternative to traditional training methods. However, while substantial work has been done in the area of real-time soft tissue modeling, little has been done to study the problem of contacts occurring during tissue manipulation. In this paper we introduce a new method for correctly handling complex contacts between various combination of rigid and deformable objects. Our approach verifies Signorini's law by combining Lagrange multipliers and the status method to solve unilateral constraints. Our method handles both concave and convex surfaces by using a displacement subdivision strategy, and the proposed algorithm allows interactive computation times even in very constrained situations. We demonstrate the efficiency of our approach in the context of interventional radiology, with the navigation of catheters and guidewires in tortuous vessels and with the deployment of coils to treat aneurysms.

  11. Similarity theory of lubricated Hertzian contacts

    NASA Astrophysics Data System (ADS)

    Snoeijer, J. H.; Eggers, J.; Venner, C. H.

    2013-10-01

    We consider a heavily loaded, lubricated contact between two elastic bodies at relative speed U, such that there is substantial elastic deformation. As a result of the interplay between hydrodynamics and non-local elasticity, a fluid film develops between the two solids, whose thickness scales as U3/5. The film profile h is selected by a universal similarity solution along the upstream inlet. Another similarity solution is valid at the outlet, which exhibits a local minimum in the film thickness. The two solutions are connected by a hyperbolic problem underneath the contact. Our asymptotic results for a soft sphere pressed against a hard wall are shown to agree with both experiment and numerical simulations.

  12. Direct contact, binary fluid geothermal boiler

    DOEpatents

    Rapier, P.M.

    1979-12-27

    Energy is extracted from geothermal brines by direct contact with a working fluid such as isobutane which is immiscible with the brine in a geothermal boiler. The geothermal boiler provides a distributor arrangement which efficiently contacts geothermal brine with the isobutane in order to prevent the entrainment of geothermal brine in the isobutane vapor which is directed to a turbine. Accordingly the problem of brine carryover through the turbine causing corrosion and scaling thereof is eliminated. Additionally the heat exchanger includes straightening vanes for preventing startup and other temporary fluctuations in the transitional zone of the boiler from causing brine carryover into the turbine. Also a screen is provided in the heat exchanger to coalesce the working fluid and to assist in defining the location of the transitional zone where the geothermal brine and the isobutane are initially mixed.

  13. Direct contact, binary fluid geothermal boiler

    DOEpatents

    Rapier, Pascal M.

    1982-01-01

    Energy is extracted from geothermal brines by direct contact with a working fluid such as isobutane which is immiscible with the brine in a geothermal boiler. The geothermal boiler provides a distributor arrangement which efficiently contacts geothermal brine with the isobutane in order to prevent the entrainment of geothermal brine in the isobutane vapor which is directed to a turbine. Accordingly the problem of brine carry-over through the turbine causes corrosion and scaling thereof is eliminated. Additionally the heat exchanger includes straightening vanes for preventing startup and other temporary fluctuations in the transitional zone of the boiler from causing brine carryover into the turbine. Also a screen is provided in the heat exchanger to coalesce the working fluid and to assist in defining the location of the transitional zone where the geothermal brine and the isobutane are initially mixed.

  14. Electron transport in carbon wires in contact with Ag electrodes: a detailed first principles investigation.

    PubMed

    Bonardi, Paolo; Achilli, Simona; Tantardini, Gian Franco; Martinazzo, Rocco

    2015-07-28

    The structure and electronic properties of carbon atom chains Cn in contact with Ag electrodes are investigated in detail with first principles means. The ideal Ag(100) surface is used as a model for binding, and electron transport through the chains is studied as a function of their length, applied bias voltage, presence of capping atoms (Si, S) and adsorption site. It is found that the metal-molecule bond largely influences electronic coupling to the leads. Without capping atoms the quality of the electric contact improves when increasing the carbon atom coordination number to the metal (1, 2 and 4 for adsorption on a top, bridge and hollow position, respectively) and this finding translates almost unchanged in more realistic tip-like contacts which present one, two or four metal atoms at the contact. Current-voltage characteristics show Ohmic behaviour over a wide range of bias voltages and the resulting conductances change only weakly when increasing the wire length. The effect of a capping species is typically drastic, and either largely reduces (S) or largely increases (Si) the coupling of the wire to the electrodes. Comparison of our findings with recent experimental results highlights the limits of the adopted approach, which can be traced back to the known gap problem of density-functional-theory. PMID:26106869

  15. Problemes theoriques et methodologiques dans l'etude des langues/dialectes en contact aux niveaux macrologique et micrologique = Theoretical and Methodological Issues in the Study of Languages/Dialects in Contact at Macro- and Micro-Logical Levels of Analysis. Proceedings of the International Conference DALE (University of London)/ICRB (Laval University, Quebec)/ICSBT (Vrije Universiteit te Brussel) (London, England, May 23-26, 1985).

    ERIC Educational Resources Information Center

    Blanc, Michel, Ed.; Hamers, Josiane F., Ed.

    Papers from an international conference on the interaction of languages and dialects in contact are presented in this volume. Papers include: "Quelques reflexions sur la variation linguistique"; "The Investigation of 'Language Continuum' and 'Diglossia': A Macrological Case Study and Theoretical Model"; "A Survey of Dialect Grammar in British…

  16. Molecular dynamics study of contact mechanics: contact area and interfacial separation from small to full contact

    NASA Astrophysics Data System (ADS)

    Yang, Chunyan; Persson, Bo

    2008-03-01

    We report a molecular dynamics study of the contact between a rigid solid with a randomly rough surface and an elastic block with a flat surface. We study the contact area and the interfacial separation from small contact (low load) to full contact (high load). For small load the contact area varies linearly with the load and the interfacial separation depends logarithmically on the load [1-4]. For high load the contact area approaches to the nominal contact area (i.e., complete contact), and the interfacial separation approaches to zero. The present results may be very important for soft solids, e.g., rubber, or for very smooth surfaces, where complete contact can be reached at moderate high loads without plastic deformation of the solids. References: [1] C. Yang and B.N.J. Persson, arXiv:0710.0276, (to appear in Phys. Rev. Lett.) [2] B.N.J. Persson, Phys. Rev. Lett. 99, 125502 (2007) [3] L. Pei, S. Hyun, J.F. Molinari and M.O. Robbins, J. Mech. Phys. Sol. 53, 2385 (2005) [4] M. Benz, K.J. Rosenberg, E.J. Kramer and J.N. Israelachvili, J. Phy. Chem. B.110, 11884 (2006)

  17. A contact map matching approach to protein structure similarity analysis.

    PubMed

    de Melo, Raquel C; Lopes, Carlos Eduardo R; Fernandes, Fernando A; da Silveira, Carlos Henrique; Santoro, Marcelo M; Carceroni, Rodrigo L; Meira, Wagner; Araújo, Arnaldo de A

    2006-01-01

    We modeled the problem of identifying how close two proteins are structurally by measuring the dissimilarity of their contact maps. These contact maps are colored images, in which the chromatic information encodes the chemical nature of the contacts. We studied two conceptually distinct image-processing algorithms to measure the dissimilarity between these contact maps; one was a content-based image retrieval method, and the other was based on image registration. In experiments with contact maps constructed from the protein data bank, our approach was able to identify, with greater than 80% precision, instances of monomers of apolipoproteins, globins, plastocyanins, retinol binding proteins and thioredoxins, among the monomers of Protein Data Bank Select. The image registration approach was only slightly more accurate than the content-based image retrieval approach. PMID:16819709

  18. Forcing contact inhibition of locomotion.

    PubMed

    Roycroft, Alice; Mayor, Roberto

    2015-07-01

    Contact inhibition of locomotion drives a variety of biological phenomenon, from cell dispersion to collective cell migration and cancer invasion. New imaging techniques have allowed contact inhibition of locomotion to be visualised in vivo for the first time, helping to elucidate some of the molecules and forces involved in this phenomenon.

  19. Fabricating customized hydrogel contact lens

    PubMed Central

    Childs, Andre; Li, Hao; Lewittes, Daniella M.; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F.

    2016-01-01

    Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spectra range from 400 nm to 800 nm. The Young’s modulus (1.47 MPa) and hydrophobicity (with a sessile drop contact angle of 40.5°) have also been characterized experimentally. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens. Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies. PMID:27748361

  20. Fabricating customized hydrogel contact lens

    NASA Astrophysics Data System (ADS)

    Childs, Andre; Li, Hao; Lewittes, Daniella M.; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F.

    2016-10-01

    Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spectra range from 400 nm to 800 nm. The Young’s modulus (1.47 MPa) and hydrophobicity (with a sessile drop contact angle of 40.5°) have also been characterized experimentally. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens. Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies.