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Sample records for contact problems current

  1. INSTRUMENTS AND METHODS OF INVESTIGATION: Solid-solid thermal contact problems: current understanding

    NASA Astrophysics Data System (ADS)

    Mesnyankin, Sergei Yu; Vikulov, Aleksei G.; Vikulov, Dmitrii G.

    2009-09-01

    The past 40 years of theoretical and experimental research on contact heat transfer are reviewed. Thermophysical and mechanical processes involved in heat flow propagation through various kinds of solid-solid joints are considered. Analytical and semiempirical expressions are presented, which simulate these processes both under vacuum conditions and in the presence of a heat-conducting medium in gaps. Reasons for the experimentally examined heat flux rectification are explained. Studies on thermal contact under a nonstationary regime are covered, as is the possibility of applying classical heat conduction theory to describing the contact thermal properties. A thermodynamic interpretation of the thermal contact resistance is suggested and basic approaches to the study of contact phenomena are described. The heat conduction in nanosystems is briefly reviewed. Theoretical problems yet to be solved are pointed out and possible solution methods suggested.

  2. Current contact lens care systems.

    PubMed

    Rakow, Phyllis L

    2003-09-01

    Contact lens care has been revolutionized and simplified with the development of multipurpose solutions, less sensitizing preservatives and disinfectants, better protein removers, and reaction-free, one-bottle care systems for patients who have had adverse responses to existing care products. As the complexity of lens care has decreased, compliance has increased. Nevertheless, good compliance is dependent on technician training and a thorough understanding of the chemistry and mechanism of action of each care system. Care products are constantly evolving, and the practitioner should become familiar with each new solution as it is introduced to ensure that patients are also kept up-to-date.

  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. Pulsed Current Static Electrical Contact Experiment

    DTIC Science & Technology

    2006-05-01

    between 6061-T6 aluminum and copper ( Glidcop AL - 25 ) during a 40 kA current pulse for two different force levels is shown in Fig. 7. For the 0.445 kN...as a function of initial contact pressures, current density, and polarity for dissimilar ( Al /Cu) metal contacts. Thermal effects on the surfaces...International Symposium on Electromagnetic Launch Technology (EML), Held May 22 - 25 , 2006 in Potsdam, Brandenburg, Germany Copyright 2006 IEEE. Published in

  5. Mixed formulation for frictionless contact problems

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Kim, Kyun O.

    1989-01-01

    Simple mixed finite element models and a computational precedure are presented for the solution of frictionless contact problems. The analytical formulation is based on a form of Reissner's large rotation theory of the structure with the effects of transverse shear deformation included. The contact conditions are incorporated into the formulation by using a perturbed Lagrangian approach with the fundamental unknowns consisting of the internal forces (stress resultants), the generalized displacements, and the Lagrange multipliers associated with the contact conditions. The element characteristic array are obtained by using a modified form of the two-field Hellinger-Reissner mixed variational principle. The internal forces and the Lagrange multipliers are allowed to be discontinuous at interelement boundaries. The Newton-Raphson iterative scheme is used for the solution of the nonlinear algebraic equations, and the determination of the contact area and the contact pressures.

  6. 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.

  7. 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…

  8. On uniqueness for frictional contact rate problems

    NASA Astrophysics Data System (ADS)

    Radi, E.; Bigoni, D.; Tralli, A.

    1999-02-01

    A linear elastic solid having part of the boundary in unilateral frictional contact witha stiffer constraint is considered. Bifurcations of the quasistatic velocity problem are analyzed,making use of methods developed for elastoplasticity. An exclusion principle for bifurcation isproposed which is similar, in essence, to the well-known exclusion principle given by Hill, 1958. Sufficient conditions for uniqueness are given for a broad class of contactconstitutive equations. The uniqueness criteria are based on the introduction of linear comparisoninterfaces defined both where the contact rate constitutive equation are piece-wise incrementallylinear and where these are thoroughly nonlinear. Structural examples are proposed which giveevidence to the applicability of the exclusion criteria.

  9. Different Points of a Continuum? Cross Sectional Comparison of the Current and Pre-contact Psychosocial Problems among the Different Categories of Adolescents in Institutional Care in Nigeria

    PubMed Central

    2012-01-01

    Background The combination of adverse social indicators and a predominantly youthful population puts Nigeria, and indeed many countries of sub-Sahara Africa, at the risk of explosion in the number of youth coming in contact with the juvenile justice system. Despite this risk, custodial childcare systems in the region are still poorly developed with both juvenile offenders and neglected adolescents coming in contact with the systems being kept in the same incarcerating facility. The needs of these different groups of adolescents may be different. Knowing their common and unique needs can inform common prevention strategies and ensure that specific service-needs of different categories of adolescents in institutional custody are met. Methods Data on the family background, pre-contact social circumstance, neurological and anthropometric profiles, and certain aspects of mental health of adolescents drawn from two juvenile justice institutions in Nigeria were obtained. The results for the adolescents on ‘criminal code’ and those admitted as a case of child neglect were compared using chi-square and odd ratios. Results Participants were 211 adolescents comprising of 158 on ‘criminal code’ and 53 declared as ‘neglected’. A lot of similarities were found. For instance, the prevalence of parental separation, family transition, experience of street-life and lifetime exposure to traumatic events and posttraumatic stress was equally high among the two groups of adolescents. The adolescents on ‘criminal code’ however had significantly higher prevalence of conduct and alcohol/substance use disorders while the child neglect group had poorer anthropometric profiles and higher prevalence of neurological disorders. Conclusions Child neglect and juvenile delinquency in Nigeria may truly be different points of a continuum. There are however fundamental differences that can warrant specific prevention strategies and tailor-made service provision while in custodial care

  10. Different points of a continuum? Cross sectional comparison of the current and pre-contact psychosocial problems among the different categories of adolescents in institutional care in Nigeria.

    PubMed

    Atilola, Olayinka

    2012-07-26

    The combination of adverse social indicators and a predominantly youthful population puts Nigeria, and indeed many countries of sub-Sahara Africa, at the risk of explosion in the number of youth coming in contact with the juvenile justice system. Despite this risk, custodial childcare systems in the region are still poorly developed with both juvenile offenders and neglected adolescents coming in contact with the systems being kept in the same incarcerating facility. The needs of these different groups of adolescents may be different. Knowing their common and unique needs can inform common prevention strategies and ensure that specific service-needs of different categories of adolescents in institutional custody are met. Data on the family background, pre-contact social circumstance, neurological and anthropometric profiles, and certain aspects of mental health of adolescents drawn from two juvenile justice institutions in Nigeria were obtained. The results for the adolescents on 'criminal code' and those admitted as a case of child neglect were compared using chi-square and odd ratios. Participants were 211 adolescents comprising of 158 on 'criminal code' and 53 declared as 'neglected'. A lot of similarities were found. For instance, the prevalence of parental separation, family transition, experience of street-life and lifetime exposure to traumatic events and posttraumatic stress was equally high among the two groups of adolescents. The adolescents on 'criminal code' however had significantly higher prevalence of conduct and alcohol/substance use disorders while the child neglect group had poorer anthropometric profiles and higher prevalence of neurological disorders. Child neglect and juvenile delinquency in Nigeria may truly be different points of a continuum. There are however fundamental differences that can warrant specific prevention strategies and tailor-made service provision while in custodial care.

  11. 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…

  12. Reduction technique for tire contact problems

    NASA Astrophysics Data System (ADS)

    Noor, Ahmed K.; Peters, Jeanne M.

    1995-04-01

    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.

  13. 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.

  14. 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.

  15. Finite Element Model for Gap Contact Problems

    DTIC Science & Technology

    1991-08-01

    22 8.1 Axisymmetric Perfectly Plastic Problem ............................... 22 8.2 Flat Gap-Coarse Grid Problem...Axisymmetric Perfectly Plastic Problem . The purpose of the first example is to check the elastic-plastic capability of the SAAC program. This is done by

  16. Singular solutions of contact problems and block elements

    NASA Astrophysics Data System (ADS)

    Babeshko, V. A.; Evdokimova, O. V.; Babeshko, O. M.

    2017-07-01

    In this work, we consider mixed problems of elasticity theory, in particular, contact problems for cases that are nontraditional. They include mixed problems with discontinuous boundary conditions in which the singularities in the behavior of contact stresses are not studied or the energy of the singularities is unbounded. An example of such mixed problems is contact problems for two rigid stamps approaching each other by rectilinear boundaries up to contact but not merging into one stamp. It has been shown that such problems, which appear in seismology, failure theory, and civil engineering, have singular components with unbounded energy and can be solved by topological methods with pointwise convergence, in particular, by the block element method. Numerical methods that are based on using the energy integral are not applicable to such problems in view of its divergence.

  17. Solution procedure of dynamical contact problems with friction

    NASA Astrophysics Data System (ADS)

    Abdelhakim, Lotfi

    2017-07-01

    Dynamical contact is one of the common research topics because of its wide applications in the engineering field. The main goal of this work is to develop a time-stepping algorithm for dynamic contact problems. We propose a finite element approach for elastodynamics contact problems [1]. Sticking, sliding and frictional contact can be taken into account. Lagrange multipliers are used to enforce non-penetration condition. For the time discretization, we propose a scheme equivalent to the explicit Newmark scheme. Each time step requires solving a nonlinear problem similar to a static friction problem. The nonlinearity of the system of equation needs an iterative solution procedure based on Uzawa's algorithm [2][3]. The applicability of the algorithm is illustrated by selected sample numerical solutions to static and dynamic contact problems. Results obtained with the model have been compared and verified with results from an independent numerical method.

  18. 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.

  19. Thimerosal: current sources of contact in Brazil.

    PubMed

    Rocha, Vanessa Barreto; Scherrer, Maria Antonieta Rios

    2014-01-01

    Thimerosal is an organic mercury derivative found in ophthalmic solutions and certain vaccines in Brazil. Although most studies suggest the prevalence of thimerosal sensitivity to be quite high, this condition does not currently have any clinical relevance. The present article surveyed 184 Brazilian products (151 topical medications and 33 vaccines) and found that thimerosal was only present in 3 ophthalmic solutions and 5 vaccines.

  20. Contact Lenses for Keratoconus- Current Practice

    PubMed Central

    Moschos, Marilita M.; Nitoda, Eirini; Georgoudis, Panagiotis; Balidis, Miltos; Karageorgiadis, Eleftherios; Kozeis, Nikos

    2017-01-01

    Background: Keratoconus is a chronic, bilateral, usuallly asymmetrical, non-inflammatory, ectatic disorder, being characterized by progressive steepening, thinning and apical scarring of the cornea. Initially, the patient is asymptomatic, but the visual acuity gradually decreases, resulting in significant vision loss due to the development of irregular astigmatism, myopia, corneal thinning and scarring. The classic treatment of visual rehabilitation in keratoconus is based on spectacles and contact lenses (CLs). Objective: To summarize the types of CLs used in the treatment of keratoconus. This is literature review of several important published articles focusing on the visual rehabilitation in keratoconus with CLs. Method: Gas permeable (GP) CLs have been found to achieve better best corrected visual acuity than spectacles, eliminating 3rd-order coma root-mean-square (RMS) error, 3rd-order RMS, and higher-order RMS. However, they have implicated in reduction of corneal basal epithelial cell and anterior stromal keratocyte densities. Soft CLs seem to provide greater comfort and lower cost, but the low oxygen permeability (if the lens is not a silicone hydrogel), and the inability to mask moderate to severe irregular astigmatism are the main disadvantages of them. On the other hand, scleral CLs ensure stable platforms, which eliminate high-order aberrations and provide good centration and visual acuity. Their main disadvantages include the difficulties in application and removal of these lenses along with corneal flattening and swelling. Result: The modern hybrid CLs are indicated in cases of poor centration, poor stability or intolerance with GP lenses. Finally, piggyback CL systems effectively ameliorate visual acuity, but they have been related to corneal neovascularization and giant papillary conjunctivitis. Conclusion: CLs seem to rehabilitate visual performance, diminishing the power of the cylinder and the high-order aberrations. The final choice of CLs is

  1. Contact Lenses for Keratoconus- Current Practice.

    PubMed

    Moschos, Marilita M; Nitoda, Eirini; Georgoudis, Panagiotis; Balidis, Miltos; Karageorgiadis, Eleftherios; Kozeis, Nikos

    2017-01-01

    Keratoconus is a chronic, bilateral, usuallly asymmetrical, non-inflammatory, ectatic disorder, being characterized by progressive steepening, thinning and apical scarring of the cornea. Initially, the patient is asymptomatic, but the visual acuity gradually decreases, resulting in significant vision loss due to the development of irregular astigmatism, myopia, corneal thinning and scarring. The classic treatment of visual rehabilitation in keratoconus is based on spectacles and contact lenses (CLs). To summarize the types of CLs used in the treatment of keratoconus. This is literature review of several important published articles focusing on the visual rehabilitation in keratoconus with CLs. Gas permeable (GP) CLs have been found to achieve better best corrected visual acuity than spectacles, eliminating 3rd-order coma root-mean-square (RMS) error, 3rd-order RMS, and higher-order RMS. However, they have implicated in reduction of corneal basal epithelial cell and anterior stromal keratocyte densities. Soft CLs seem to provide greater comfort and lower cost, but the low oxygen permeability (if the lens is not a silicone hydrogel), and the inability to mask moderate to severe irregular astigmatism are the main disadvantages of them. On the other hand, scleral CLs ensure stable platforms, which eliminate high-order aberrations and provide good centration and visual acuity. Their main disadvantages include the difficulties in application and removal of these lenses along with corneal flattening and swelling. The modern hybrid CLs are indicated in cases of poor centration, poor stability or intolerance with GP lenses. Finally, piggyback CL systems effectively ameliorate visual acuity, but they have been related to corneal neovascularization and giant papillary conjunctivitis. CLs seem to rehabilitate visual performance, diminishing the power of the cylinder and the high-order aberrations. The final choice of CLs is based on their special features, the subsequent

  2. Thimerosal: current sources of contact in Brazil*

    PubMed Central

    Rocha, Vanessa Barreto; Scherrer, Maria Antonieta Rios

    2014-01-01

    Thimerosal is an organic mercury derivative found in ophthalmic solutions and certain vaccines in Brazil. Although most studies suggest the prevalence of thimerosal sensitivity to be quite high, this condition does not currently have any clinical relevance. The present article surveyed 184 Brazilian products (151 topical medications and 33 vaccines) and found that thimerosal was only present in 3 ophthalmic solutions and 5 vaccines. PMID:24770530

  3. High current density stability of ohmic contacts to silicon carbide

    NASA Astrophysics Data System (ADS)

    Downey, Brian P.

    The materials properties of SiC, such as wide bandgap, high breakdown electric field, and good thermal conductivity, make it an appealing option for high temperature and high power applications. The replacement of Si devices with SiC components could lead to a reduction in device size, weight, complexity, and cooling requirements along with an increase in device efficiency. One area of concern under high temperature or high current operation is the stability of the ohmic contacts. Ohmic contact degradation can cause an increase in parasitic resistance, which can diminish device performance. While contact studies have primarily focused on the high temperature stability of ohmic contacts to SiC, different failure mechanisms may arise under high current density stressing due to the influence of electromigration. In addition, preferential degradation may occur at the anode or cathode due to the directionality of current flow, known as a polarity effect. The failure mechanisms of ohmic contacts to p-type SiC under high current density stressing are explored. Complementary materials characterization techniques were used to analyze contact degradation, particularly the use of cross-sections prepared by focused ion beam for imaging using field emission scanning electron microscopy and elemental analysis using Auger electron spectroscopy. Initially the degradation of commonly studied Ni and Al-based contacts was investigated under continuous DC current. The contact metallization included a bond pad consisting of a TiW diffusion barrier and thick Au overlayer. The Ni contacts were found to degrade due to the growth of voids within the ohmic contact layer, which were initially produced during the high temperature Ni/SiC ohmic contact anneal. The Al-based contacts degraded due to the movement of Al from the ohmic contact layer to the surface of the Au bond pad, and the movement of Au into the ohmic contact layer from the bond pad. The inequality of Al and Au fluxes generated

  4. 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.

  5. Contact problem for a transversely isotropic half-space with an unknown contact region

    NASA Astrophysics Data System (ADS)

    Pozharskii, D. A.

    2014-03-01

    A three-dimensional contact problem with an unknown contact region for a transversely isotropic half-space, when the isotropy planes are perpendicular to the half-space boundary, is investigated. The method described makes it possible to evaluate effectively the Brinell and Vickers hardness and the contact strength of materials, the near-surface properties of which can substantially depend on the direction (titanium, zinc, beryllium, cobalt, aluminum and zinc oxides, graphite, wood, temoral bone, sapphire, etc; five elastic constants). We use the fact that the kernel of the integral equation of a contact problem can be represented in a form free of quadratures. Such a form of the kernel, in view of the simplicity of its regularization in singular points, makes it possible to apply the method of nonlinear boundary integral equations developed by Galanov to solve the contact problem with an unknown contact region. To debug the computer program, an exact solution of the contact problem for a stamp shaped like an elliptic paraboloid is used. Calculations are made for various materials with the incorporation of the stamp shaped as a rectangular pyramid. The contact regions, pressures, and the values of the impressing force with the specified stamp immersion are determined.

  6. Fracture and contact problems for an elastic wedge

    NASA Technical Reports Server (NTRS)

    Erdogan, F.; Arin, K.

    1976-01-01

    The paper deals with the plane elastostatic contact problem for an infinite elastic wedge of arbitrary angle. The medium is loaded through a frictionless rigid wedge of a given symmetric profile. Using the Mellin transform formulation the mixed boundary value problem is reduced to a singular integral equation with the contact stress as the unknown function. With the application of the results to the fracture of the medium in mind, the main emphasis in the study has been on the investigation of the singular nature of the stress state around the apex of the wedge and on the determination of the contact pressure.

  7. Fracture and contact problems for an elastic wedge

    NASA Technical Reports Server (NTRS)

    Erdogan, F.; Arin, K.

    1974-01-01

    The plane elastostatic contact problem for an infinite elastic wedge of arbitrary angle is discussed. The medium is loaded through a frictionless rigid wedge of a given symmetric profile. Using the Mellin transform formulation the mixed boundary value problem is reduced to a singular integral equation with the contact stress as the unknown function. With the application of the results to the fracture of the medium in mind, the main emphasis in the study has been on the investigation of the singular nature of the stress state around the apex of the wedge and on the determination of the contact pressure.

  8. Isogeometric treatment of frictional contact and mixed mode debonding problems

    NASA Astrophysics Data System (ADS)

    Dimitri, Rossana; Zavarise, Giorgio

    2017-08-01

    Nowadays the isogeometric analysis (IGA) represents an innovative method that merges design and numerical computations into a unified formulation. In such a context we apply the isogeometric concept based on T-splines and Non Uniform Rational B-Splines (NURBS) discretizations to study the interfacial contact and debonding problems between deformable bodies in large deformations. More in detail, we develop and test a generalized large deformation contact algorithm which accounts for both frictional contact and mixed-mode cohesive debonding in a unified setting. Some numerical examples are provided for varying resolutions of the contact and/or cohesive zone, which show the accuracy of the solutions and demonstrate the potential of the method to solve challenging 2D contact and debonding problems. The superior accuracy of T-splines with respect to NURBS interpolations for a given number of degrees of freedom (Dofs) is always proved.

  9. High current density contacts for photoconductive semiconductor switches

    SciTech Connect

    Baca, A.G.; Hjalmarson, H.P.; Loubriel, G.M.; McLaughlin, D.L.; Zutavern, F.J.

    1993-08-01

    The current densities implied by current filaments in GaAs photoconductive semiconductor switches (PCSS) are in excess of 1 MA/cm{sup 2}. As the lateral switches are tested repeatedly, damage accumulates at the contacts until electrical breakdown occurs across the surface of the insulating region. In order to improve the switch lifetime, the incorporation of n- and p-type ohmic contacts in lateral switches as well as surface geometry modifications have been investigated. By using p-type AuBe ohmic contacts at the anode and n-type AuGe ohmic contacts at the cathode, contact lifetime improvements of 5--10x were observed compared to switches with n-type contacts at both anode and cathode. Failure analysis on samples operated for 1--1,000 shots show that extensive damage still exists for at least one contact on all switches observed and that temperatures approaching 500{degrees}C are can be reached. However, the n-type AuGe cathode is often found to have no damage observable by scanning electron microscopy (SEM). The observed patterns of contact degradation indicate directions for future contact improvements in lateral switches.

  10. Physician-patient sexual contact. Prevalence and problems.

    PubMed Central

    Gartrell, N K; Milliken, N; Goodson, W H; Thiemann, S; Lo, B

    1992-01-01

    To document the current prevalence of physician-patient sexual contact and to estimate its effect on involved patients, 10,000 family practitioners, internists, obstetrician-gynecologists, and surgeons were surveyed. Of the 1,891 respondents, 9% acknowledged sexual contact with 1 or more patients. Even in the unlikely case that none of the nonrespondents had sexual contact with patients, its prevalence among all 10,000 physicians surveyed would still be 2%. Of respondents, 23% had at least 1 patient who reported sexual contact with another physician; 63% thought this contact was "always harmful" to the patients. Almost all (94%) responding physicians opposed sexual contact with current patients; 37% also opposed sexual contact with former patients. More than half of respondents (56%) indicated that physician-patient sexual contact had never been addressed in their training; only 3% had participated in a continuing education course focusing on this issue. Clear and enforceable medical ethics codes concerning physician-patient sexual contact are needed, as well as preventive educational programs for medical schools and residency programs. PMID:1441462

  11. Formulations and computational methods for contact problems in solid mechanics

    NASA Astrophysics Data System (ADS)

    Mirar, Anand Ramchandra

    2000-11-01

    A study of existing formulations and computational methods for contact problems is conducted. The purpose is to gain insights into the solution procedures and pinpoint their limitations so that alternate procedures can be developed. Three such procedures based on the augmented Lagrangian method (ALM) are proposed. Small-scale benchmark problems are solved analytically as well as numerically to study the existing and proposed methods. The variational inequality formulation for frictionless contact is studied using the two bar truss-wall problem in a closed form. Sub-differential formulation is investigated using the spring-wall contact and the truss-wall friction problems. A two-phase analytical procedure is developed for solving the truss-wall frictional contact benchmark problem. The variational equality formulation for contact problems is studied using the penalty method along with the Newton-Raphson procedure. Limitations of such procedures, mainly due to their dependence on the user defined parameters (i.e., the penalty values and the number of time steps), are identified. Based on the study it is concluded that alternate formulations need to be developed. Frictionless contact formulation is developed using the basic concepts of ALM from optimization theory. A new frictional contact formulation (ALM1) is then developed employing ALM. Automatic penalty update procedure is used to eliminate dependence of the solution on the penalty values. Dependence of the solution on the number of time steps in the existing as well as ALM1 formulations is attributed to a flaw in the return mapping procedure for friction. Another new frictional contact formulation (ALM2) is developed to eliminate the dependence of solution on the number of time steps along with the penalty values. Effectiveness of ALM2 is demonstrated by solving the two bar and five bar truss-wall problems. The solutions are compared with the analytical and existing formulations. Design sensitivity analysis of

  12. The caustics method in the contact problems of anisotropic materials

    NASA Astrophysics Data System (ADS)

    Bakić, A.; Semenski, D.; Jecić, S.

    2010-06-01

    Regions with high stress gradients represent critical zones of engineering structures such as crack tip or vicinity of the contact zone. The optical method of caustics is one of the few experimental methods which provide applicable results in these locations. This method was originally developed for crack-tip measurements of stress intensity factors and J-integral for isotropic and then for anisotropic materials. Subsequently, it was extended to contact problems where the size and shape of caustics on the screen are related to the amount and the inclination of loading force. Here, the method of caustics is extended to the analysis of contact problems for mechanically anisotropic materials. This makes the caustics method widely applicable to the analysis of any high stress gradient locations in a structure.

  13. Favism: Current Problems and Investigations

    PubMed Central

    Bottini, E.

    1973-01-01

    Haemolytic favism is a severe, acute anaemia which occurs in glucose-6-phosphate dehydrogenase deficient individuals, usually following the ingestion of Vicia faba seeds. Current interest is focused on the nature of the active substances of Vicia faba and on the causes of the varying susceptibility among G6PD-deficient individuals to episodes of severe haemolysis. The results of experiments in vitro favour the hypothesis that Vicia faba contains several active substances which may act in a synergistic way. Red cell acid phosphatase and thalassaemia genes appear to play a remarkable role in conditioning the susceptibility to severe haemolysis in G6PD-deficient subjects. In addition to erythrocyte enzymes and to enzymes which intervene in the absorption and metabolism of the active substances of Vicia faba, another field for future investigations may be that of plasma factors which influence the stability of reduced glutathione in the red cells. PMID:4714581

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

    DOEpatents

    Trutna, W.R.

    1997-12-09

    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. 13 figs.

  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. A Solution Method for Large Deformation Contact Problems.

    DTIC Science & Technology

    1984-10-01

    number) Contact Problem Algorithm Implicit Solution Technique 20. ANSTNACT’ (rntftae r eves aIi N yaeemy mrd identify by block numnber) P. solution...WITHOUT oL0 H! 0-CONTACT ALGORITHM Z w 00 0 ev 0.8- w kL 0.0 0 U< O0.26 U)_ * z Z OBTINE 0H53 56 59 ANGE,4 Ficure~~~~~ ~*A G RI H 17 Peitdtatoso iesi itrae...41, Division of Applied Sciences, Harvard Univ., March 1983. [20] Rabinowicz , E., Friction and Wear of Materials, J. Wiley and Sons, 1965. [21

  17. Contact problems for a finitely deformed incompressible elastic halfspace

    NASA Astrophysics Data System (ADS)

    Selvadurai, A. P. S.

    2015-01-01

    This paper examines the class of problems related to the interaction between a finitely deformed incompressible elastic halfspace and contacting elements that include smooth, flat rigid indenters with elliptical and circular shapes and a thick plate of infinite extent. The contact between the finitely deformed elastic halfspace and the contacting elements is assumed to be bilateral. The interaction between both the rigid circular indenter and the finitely deformed halfspace is induced by a Mindlin force that acts at the interior of the halfspace regions and by exterior loads. Similar considerations apply for the contact between the flexible plate of infinite extent and the finitely deformed elastic halfspace. The theory of small deformations superposed on large deformations proposed by Green et al. (Proc R Soc Ser A 211:128-155, 1952) is used as the basis for the formulation of the problem, and results of potential theory and integral transform techniques are used to develop the analytical results. In particular, explicit results are presented for the displacement of the rigid elliptical indenter and the maximum deflection of the flexible plate induced by the Mindlin forces, when the finitely deformed halfspace region has a strain energy function of the Mooney-Rivlin form.

  18. Alternative current source based Schottky contact with additional electric field

    NASA Astrophysics Data System (ADS)

    Mamedov, R. K.; Aslanova, A. R.

    2017-07-01

    Additional electric field (AEF) in the Schottky contacts (SC) that covered the peripheral contact region wide and the complete contact region narrow (as TMBS diode) SC. Under the influence of AEF is a redistribution of free electrons produced at certain temperatures of the semiconductor, and is formed the space charge region (SCR). As a result of the superposition of the electric fields SCR and AEF occurs the resulting electric field (REF). The REF is distributed along a straight line perpendicular to the contact surface, so that its intensity (and potential) has a minimum value on the metal surface and the maximum value at a great distance from the metal surface deep into the SCR. Under the influence of AEF as a sided force the metal becomes negative pole and semiconductor - positive pole, therefore, SC with AEF becomes an alternative current source (ACS). The Ni-nSi SC with different diameters (20-1000 μm) under the influence of the AEF as sided force have become ACS with electromotive force in the order of 0.1-1.0 mV, which are generated the electric current in the range of 10-9-10-7 A, flowing through the external resistance 1000 Ohm.

  19. [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

  20. Single Nanoparticle Voltammetry: Contact Modulation of the Mediated Current.

    PubMed

    Li, Xiuting; Batchelor-McAuley, Christopher; Whitby, Samuel A I; Tschulik, Kristina; Shao, Lidong; Compton, Richard G

    2016-03-18

    The cyclic voltammetric responses of individual palladium-coated carbon nanotubes are reported. Upon impact-from the solution phase-with the electrified interface, the nanoparticles act as individual nanoelectrodes catalyzing the hydrogen-oxidation reaction. At high overpotentials the current is shown to reach a quasi-steady-state diffusion limit, allowing determination of the tube length. The electrochemical response of the individual nanotubes also reveals the system to be modulated by the electrical contact between the electrode and carbon nanotube. This modulation presents itself as fluctuations in the recorded Faradaic current.

  1. 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.

  2. Giant acoustoelectric current in suspended quantum point contacts

    NASA Astrophysics Data System (ADS)

    Kreft, Dustin J.; Mourokh, Lev G.; Shin, Hyuncheol; Bichler, Max; Wegscheider, Werner; Blick, Robert H.

    2016-12-01

    We present results on the acoustoelectric current driven through a quantum point contact (QPC) placed on a suspended nanobridge, which is subject to surface acoustic waves (SAWs). The magnitude of this current is much larger than that of a two-dimensional gas, and the system has enhanced sensitivity to perturbations. In particular, the current oscillations as a function of magnetic field exhibit additional features associated with the spin splitting. Furthermore, the negative voltage applied to the QPC gates induces the oscillations revealing the subband structure not seen in transport measurements at the elevated temperatures of our experiment. Near the pinch off conditions, the acoustoelectric current becomes negative which we attribute to the enhanced backscattering caused by the SAW-phonons' absorption and emission.

  3. 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…

  4. Current transport mechanism of p-GaN Schottky contacts

    NASA Astrophysics Data System (ADS)

    Shiojima, Kenji; Sugahara, Tomoya; Sakai, Shiro

    2000-12-01

    Transient measurements of I-V and depletion layer capacitance were conducted to clarify the leaky current flow mechanism in Ni Schottky contacts formed on Mg-doped p-GaN. We found that carrier capture and emission from acceptor-like deep level defects cause depletion layer width (Wdep) to vary significantly. Upon ionization of the defects by white light, which results in small Wdep, current can go through the Schottky barrier and a leaky I-V curve is observed. Upon filling by current injection, Wdep becomes larger and the large original Schottky barrier height is seen. The time constant of carrier emission is as long as 8.3×103 min.

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

    NASA Astrophysics Data System (ADS)

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

    Internal current collection efficiencies greater than 90% and energy conversion efficiencies of 18 % at 30 suns were measured on a laboratory version of the interdigitated back contact (IBC) solar cell. A phosphorous gettering diffusion was performed on the front surface and then etched off to achieve these high current collection efficiencies. 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. It is suggested that this should result in higher efficiencies at high concentration.

  6. 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…

  7. 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…

  8. Evaluation of Contact Loss and Wear Considering the Friction Under Electric Current for Sliding Contact in Electric Railway

    NASA Astrophysics Data System (ADS)

    Kimura, Yoshio; Mishina, Hiroshi

    At the contact point of current collector of railway, it is difficult to investigate the relation between the wear and the electric current because of many influence factors and the sliding conditions. Therefore we need to show this relation by means of smaller current conditions than railway to see the effects of electric current on friction and wear. Experimental device is pin-on-wire type, which we improve pin-on-disk type sliding system into. It is set in a direct-current circuit and the pin rubs wires under an electric current. At this point, there is not only the mechanical phenomenon by adhesive wear, but also the electric phenomena including fusion caused by the heat from constriction resistance and the arc discharge caused by the contact loss during sliding test. To examine the effects on the wear of contact materials by them, we investigate the details classifying contact loss, which has a great influence on the wear of contact materials, to two kinds of contact loss, arc contact loss and complete contact loss. As a result of it, we can show the relations between the power supply voltage and the outbreak number, the outbreak ratio of two types of contact loss, and relations between the wear and the power supply voltage, materials by means of the former two relations. And we can see the effects of fusion and arc discharge on the sliding surface by optical microscope.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Conformal Contact Problems of Ball-socket and Ball

    NASA Astrophysics Data System (ADS)

    Sun, Zhangang; Hao, Caizhe

    This paper focuses attention on non-conformal and almost conformal contact of ball and ball-socket. Two-dimensional finite element models are developed to calculate the normal contact stress distribution and contact area. The effects of geometry dimension and external load on the contact pressure distribution and contact region are presented, respectively. Meanwhile, the results of FEM and solutions of Hertz contact theory are compared. The results indicates that contact state of ball and ball-socket changes from point contact to area contact with the increasing of the dimensionless number-curvature radius coefficient f and the number of f =0.536 (≈0.54) is critical parameter causing the change.

  15. Current Problems in Turbomachinery Fluid Dynamics.

    DTIC Science & Technology

    1982-12-31

    edge" stagnation points, " Venturi " effects in the intra-blade region, and the trailing edge Kutta conditions could all be expected, it was thought...E.M. Greitzer, lecture series on "Flow Instabilities in Gas Turbine Engines" (including inlet distortion effects , stall enhancement using casing...7 AU-A25 478 CURRENT PROBLEMS IN TURUOACHINERY FLUID DTNAMICSIUI I F CMASSACHUSETTS INST OF TECH CABRIDGO E GAS TURBINE AND A PLASMA DYNAMICS LAB I M

  16. 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 ).

  17. 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

  18. Influence of the Thomson effect on the pulse heating of high-current electrical contacts

    NASA Astrophysics Data System (ADS)

    Merkushev, A. G.; Pavleino, M. A.; Pavleino, O. M.; Pavlov, V. A.

    2014-09-01

    Pulse heating of high-current contacts is notable for the presence of considerable temperature gradients in the contact area, which cause the Thomson effect—the appearance of thermoelectric currents. The amount of this effect against conventional Joule heat release is quantitatively estimated. Pulse heating of electrical contacts is numerically simulated with the use of the Comsol program package. It is demonstrated that thermoelectric currents make a negligible contribution to heating in the case of copper contacts.

  19. Current densities and total contact currents associated with 400 kV power line tasks.

    PubMed

    Korpinen, Leena; Kuisti, Harri; Elovaara, Jarmo

    2013-12-01

    The aim of the study was to analyze all current values from measured periods while performing tasks on 400 kV power lines. Our aim was also to study the average current densities and average total contact currents caused by electric fields in 400 kV power line tasks. Two workers simulated the following tasks: (A) climbing up a portal tower, (B) climbing up a portal transposing tower, (C) working on the cross-arm of a portal tower, (D) climbing up a portal tube tower, (E) climbing up a Tannenbaum tower on the side of the energized circuit with the other circuit unenergized, (F) climbing up a Tannenbaum tower with both circuits energized, and (G) climbing up a Donau tower. The highest average current density in the neck was 2.5 mA/m(2) (calculated internal electric field 31.5-63.0 mV/m), and the highest average of the contact currents was 240.0 µA. All measured values at 400 kV towers were lower than the limit value of 10 mA/m(2) in the first version of Directive 2004/40/EC and the basic restrictions (0.1 and 0.8 V/m) of the International Commission on Non-ionizing Radiation Protection.

  20. 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.

  1. 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.

  2. 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.

  3. Advances in reduction techniques for tire contact problems

    NASA Astrophysics Data System (ADS)

    Noor, Ahmed K.

    1995-08-01

    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.

  4. 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.

  5. The problem of current toxic chemicals management.

    PubMed

    Tickner, Joel; Geiser, Ken

    2004-01-01

    In this article, we explore the limitations of current chemicals management policies worldwide and the evolution of new European, International and U.S. policies to address the problem of toxic chemicals control. It is becoming increasingly apparent that current chemicals management policies in Europe and the United States are inadequate. There is a general lack of toxicity and exposure information on chemicals in commerce and the vast majority of chemicals were considered safe until proven guilty in legislation. Governments must then prove each chemical is dangerous through a slow and resource-intensive risk assessment process. For more than a decade, Nordic countries, such as Denmark and Sweden, have actively promoted integrated chemicals policies to address contamination of critical waterways. They have successfully used a variety of voluntary and mandatory policy tools, such as education, procurement, lists of chemicals of concern, eco-labeling, research and development on safer substitutes, and chemical phase-out requirements, to encourage companies using chemicals to reduce their reliance on harmful substances and to develop safer substitutes. While previously isolated to particular countries, innovative and exciting European-wide policies to promote sustainable chemicals management are now moving forward, including the recently published draft Registration, Evaluation and Authorization of CHemicals (REACH) policy of the European Union. A sweeping change in chemicals management policies in Europe is inevitable and it will ultimately affect manufacturers in the U.S. and globally. The European movement provides an opportunity to initiate a discussion on integrated chemicals policy in the U.S. where some innovative initiatives already are underway.

  6. Posteriori error estimation of h-p finite element approximations of frictional contact problems

    NASA Astrophysics Data System (ADS)

    Lee, C. Y.; Oden, J. T.

    1994-03-01

    Dynamic and static fractional contact problems are described using the normal compliance law on the contact boundary. Dynamic problems are recast into quasistatic problems by time discretization. An a posteriori error estimator is developed for nonlinear elliptic equation of corresponding static or quasistatic problems. The a posteriori error estimator is applied to a frictionless case and extended to frictional contact problems. An adaptive strategy is introduced and h-p finite element meshes are obtained through a procedure based on a priori and a posteriori error estimations. Numerical examples are given to support the theoretical results.

  7. Optically induced current in molecular conduction nanojunctions with semiconductor contacts

    NASA Astrophysics Data System (ADS)

    Fainberg, Boris D.; Seideman, Tamar

    2013-06-01

    We propose a new approach 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 method is based on the application of intrinsic semiconductor contacts and optical frequencies below the semiconductor bandgap. To explore the coherently controlled electronic dynamics, we introduce a density matrix formalism that accounts for both the discrete molecular state and the semiconductor quasicontinua within a single master equation and offers analytically soluble limits for a single and two-site molecular bridge. 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. Our results illustrate the potential of semiconductor contacts in coherent control of photocurrent.

  8. Solution of dynamic contact problems by implicit/explicit methods. Final report

    SciTech Connect

    Salveson, M.W.; Taylor, R.L.

    1996-10-14

    The solution of dynamic contact problems within an explicit finite element program such as the LLNL DYNA programs is addressed in the report. The approach is to represent the solution for the deformation of bodies using the explicit algorithm but to solve the contact part of the problem using an implicit approach. Thus, the contact conditions at the next solution state are considered when computing the acceleration state for each explicit time step.

  9. Divide and Conquer Approach to Contact Map Overlap Problem Using 2D-Pattern Mining of Protein Contact Networks.

    PubMed

    Koneru, Suvarna Vani; Bhavani, Durga S

    2015-01-01

    A novel approach to Contact Map Overlap (CMO) problem is proposed using the two dimensional clusters present in the contact maps. Each protein is represented as a set of the non-trivial clusters of contacts extracted from its contact map. The approach involves finding matching regions between the two contact maps using approximate 2D-pattern matching algorithm and dynamic programming technique. These matched pairs of small contact maps are submitted in parallel to a fast heuristic CMO algorithm. The approach facilitates parallelization at this level since all the pairs of contact maps can be submitted to the algorithm in parallel. Then, a merge algorithm is used in order to obtain the overall alignment. As a proof of concept, MSVNS, a heuristic CMO algorithm is used for global as well as local alignment. The divide and conquer approach is evaluated for two benchmark data sets that of Skolnick and Ding et al. It is interesting to note that along with achieving saving of time, better overlap is also obtained for certain protein folds.

  10. Finite Element Analysis for Turbine Blades with Contact Problems

    NASA Astrophysics Data System (ADS)

    Yang, Yuan-Jian; Yang, Liang; Wang, Hai-Kun; Zhu, Shun-Peng; Huang, Hong-Zhong

    2016-12-01

    Turbine blades are one of the key components in a typical turbofan engine, which plays an important role in flight safety. In this paper, we establish a establishes a three-dimensional finite element model of the turbine blades, then analyses the strength of the blade in complicated conditions under the joint function of temperature load, centrifugal load, and aerodynamic load. Furthermore, contact analysis of blade tenon and dovetail slot is also carried out to study the stress based on the contact elements. Finally, the Von Mises stress-strain distributions are obtained to acquire the several dangerous points and maximum Von Mises stress, which provide the basis for life prediction of turbine blade.

  11. Children Exposed to Intimate Partner Violence: Conduct Problems, Interventions, and Partner Contact With the Child.

    PubMed

    Jouriles, Ernest N; Rosenfield, David; McDonald, Renee; Vu, Nicole L; Rancher, Caitlin; Mueller, Victoria

    2016-06-30

    Children's contact with their mother's violent partner is a potentially important variable for understanding conduct problems among children exposed to intimate partner violence (IPV). Within the context of a treatment study evaluating a parenting intervention (Project Support) for families exiting a domestic violence shelter, this study tested four hypotheses regarding children's postshelter contact with their mother's violent partner: (1) participation in Project Support decreases the frequency of children's contact with their mother's violent partner; (2) postshelter contact is positively associated with children's conduct problems and is associated more strongly for girls than boys; (3) frequency of contact mediates Project Support's effects on children's conduct problems; and (4) frequency of contact is positively associated with IPV and partner-child aggression, and these latter associations help explain effects of contact on children's conduct problems. Participants were 66 women (26 White) with a child (32 girls) between 4 and 9 years. Families were assessed every 4 months for 20 months after departure from a domestic violence shelter. Project Support reduced the extent of partner-child contact. In addition, within-subject changes in contact over time were associated with girls', but not boys', conduct problems, and it partially mediated effects of Project Support on girls' conduct problems. Higher average levels of contact over time were also positively associated with further incidents of IPV and partner-child aggression, and partner-child aggression helped explain effects of contact on children's conduct problems. Children's postshelter contact with the mother's violent partner relates positively to several negative family outcomes.

  12. Pore-scale modeling of moving contact line problems in immiscible two-phase flow.

    NASA Astrophysics Data System (ADS)

    Kucala, A.; Noble, D.; Martinez, M. J.

    2016-12-01

    Two immiscible fluids in static equilibrium form a common interface along a solid surface, characterized as the static contact (wetting) angle and is a function of surface geometry, intermolecular forces, and interfacial surface energies manifested as interfacial tension. This static configuration may become perturbed due to external force imbalances (mass injection, pressure gradients, buoyancy, etc.) and the contact line location and interface curvature becomes dynamic. Accurate modeling of moving contact line (MCL) problems is imperative in predicting capillary pressure vs. saturation curves, permeability, and preferential flow paths for a variety of applications, including geological carbon storage (GCS) and enhanced oil recovery (EOR). Here, we present a model for the moving contact line using pore-scale computational fluid dynamics (CFD) which solves the full, time-dependent Navier-Stokes equations using the Galerkin finite-element method. The MCL is modeled as a surface traction force proportional to the surface tension, dependent on the static properties of the immiscible fluid/solid system. The moving two-phase interface is tracked using the level set method and discretized with the conformal decomposition finite element method (CDFEM), allowing for surface tension effects to be computed at the exact interface location. We present a variety of verification test cases for simple two- and three-dimensional geometries to validate the current model, including threshold pressure predictions in flows through pore-throats for a variety of wetting angles. Simulations involving more complex geometries are also presented to be used in future simulations for GCS and EOR problems. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000

  13. First principles calculation of current-induced forces in atomic gold contacts

    NASA Astrophysics Data System (ADS)

    Brandbyge, Mads; Stokbro, Kurt; Taylor, Jeremy; Mozos, Jose-Luis; Ordejon, Pablo

    2002-03-01

    We have recently developed an first principles method [1] for calculating the electronic structure, electronic transport, and forces acting on the atoms, for atomic scale systems connected to semi-infinite electrodes and with an applied voltage bias. Our method is based on the density functional theory (DFT) as implemented in the well tested SIESTA program [2]. We fully deal with the atomistic structure of the whole system, treating both the contact and the electrodes on the same footing. The effect of the finite bias (including selfconsistency and the solution of the electrostatic problem) is taken into account using nonequilibrium Green's functions. In this talk we show results for the forces acting on the contact atoms due to the nonequilibrium situation in the electronic subsystem, i.e. in the presence of an electronic current. We concentrate on one atom wide gold contacts/wires connected to bulk gold electrodes. References [1] Our implementation is called TranSIESTA and is described in M. Brandbyge, J. Taylor, K. Stokbro, J-L. Mozos, and P. Ordejon, cond-mat/0110650 [2] D. Sanchez-Portal, P. Ordejon, E. Artacho and J. Soler, Int. J. Quantum Chem. 65, 453 (1997).

  14. Nanoscale Joule heating, Peltier cooling and current crowding at graphene-metal contacts

    NASA Astrophysics Data System (ADS)

    Grosse, Kyle L.; Bae, Myung-Ho; Lian, Feifei; Pop, Eric; King, William P.

    2011-05-01

    The performance and scaling of graphene-based electronics is limited by the quality of contacts between the graphene and metal electrodes. However, the nature of graphene-metal contacts remains incompletely understood. Here, we use atomic force microscopy to measure the temperature distributions at the contacts of working graphene transistors with a spatial resolution of ~10 nm (refs 5, , , 8), allowing us to identify the presence of Joule heating, current crowding and thermoelectric heating and cooling. Comparison with simulation enables extraction of the contact resistivity (150-200 Ω µm2) and transfer length (0.2-0.5 µm) in our devices; these generally limit performance and must be minimized. Our data indicate that thermoelectric effects account for up to one-third of the contact temperature changes, and that current crowding accounts for most of the remainder. Modelling predicts that the role of current crowding will diminish and the role of thermoelectric effects will increase as contacts improve.

  15. Nanoscale Joule heating, Peltier cooling and current crowding at graphene-metal contacts.

    PubMed

    Grosse, Kyle L; Bae, Myung-Ho; Lian, Feifei; Pop, Eric; King, William P

    2011-05-01

    The performance and scaling of graphene-based electronics is limited by the quality of contacts between the graphene and metal electrodes. However, the nature of graphene-metal contacts remains incompletely understood. Here, we use atomic force microscopy to measure the temperature distributions at the contacts of working graphene transistors with a spatial resolution of ~ 10 nm (refs 5-8), allowing us to identify the presence of Joule heating, current crowding and thermoelectric heating and cooling. Comparison with simulation enables extraction of the contact resistivity (150-200 Ω µm²) and transfer length (0.2-0.5 µm) in our devices; these generally limit performance and must be minimized. Our data indicate that thermoelectric effects account for up to one-third of the contact temperature changes, and that current crowding accounts for most of the remainder. Modelling predicts that the role of current crowding will diminish and the role of thermoelectric effects will increase as contacts improve.

  16. Pore-scale modeling of moving contact line problems in immiscible two-phase flow

    NASA Astrophysics Data System (ADS)

    Kucala, Alec; Noble, David; Martinez, Mario

    2016-11-01

    Accurate modeling of moving contact line (MCL) problems is imperative in predicting capillary pressure vs. saturation curves, permeability, and preferential flow paths for a variety of applications, including geological carbon storage (GCS) and enhanced oil recovery (EOR). Here, we present a model for the moving contact line using pore-scale computational fluid dynamics (CFD) which solves the full, time-dependent Navier-Stokes equations using the Galerkin finite-element method. The MCL is modeled as a surface traction force proportional to the surface tension, dependent on the static properties of the immiscible fluid/solid system. We present a variety of verification test cases for simple two- and three-dimensional geometries to validate the current model, including threshold pressure predictions in flows through pore-throats for a variety of wetting angles. Simulations involving more complex geometries are also presented to be used in future simulations for GCS and EOR problems. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  17. 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.

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

    NASA Technical Reports Server (NTRS)

    Lim, Sang G.; Brewe, David E.

    1992-01-01

    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.

  19. Field effects of current crowding in metal-MoS2 contacts

    NASA Astrophysics Data System (ADS)

    Yuan, Hui; Cheng, Guangjun; Yu, Sheng; Hight Walker, Angela R.; Richter, Curt A.; Pan, Minghu; Li, Qiliang

    2016-03-01

    Gate assisted contact-end Kelvin test structures and gate assisted four-probe structures have been designed and fabricated to measure the field effects of current crowding at the source/drain contacts of top-gate MoS2 field effect transistors. The transistors exhibited n-type transistor characteristics. The source/drain contact resistance was measured by using both gate-assisted Kelvin and gate-assisted four-probe structures. The values of contact resistance measured by these two test structures are significantly different. The contact-front contact resistance obtained from the four-probe structure is strongly influenced by field effects on current crowding, while the contact-end resistance obtained from the Kelvin test structure is not. The metal-MoS2 contact current transfer length, LT, can be determined from the comparison between these two measurements. LT was observed to increase linearly with increasing gate voltage. This work indicates that the contact characteristics can be more precisely measured when both gate-assisted test structures are used.

  20. Current issues and problems in welding science.

    PubMed

    David, S A; Debroy, T

    1992-07-24

    Losses of life and property due to catastrophic failure of structures are often traced to defective welds. However, major advances have taken place in welding science and technology in the last few decades. With the development of new methodologies at the crossroad of basic and applied sciences, the promise of science-based tailoring of composition, structure, and properties of the weldments may be fulfilled. This will require resolution of several contemporary issues and problems concerning the structure and properties of the weldments as well as intelligent control and automation of the welding processes.

  1. Current issues and problems in welding science

    SciTech Connect

    David, S.A.; DebRoy, T. )

    1992-07-24

    Losses of life and property due to catastrophic failure of structures are often traced to defective welds. However, major advances have taken place in welding science and technology in the last few decades. With the development of new methodologies at the crossroad of basic and applied sciences, the promise of science-based tailoring of composition, structure, and properties of the weldments may be fulfilled. This well require resolution of several contemporary issues and problems concerning the structure and properties of the weldments as well as intelligent control and automation of the welding processes.

  2. The axisymmetric torsional contact problem of a functionally graded piezoelectric coated half-space

    NASA Astrophysics Data System (ADS)

    Su, Jie; Ke, Liao-Liang; Wang, Yue-Sheng; Xiang, Yang

    2017-01-01

    In this article, we study the axisymmetric torsional contact problem of a half-space coated with functionally graded piezoelectric material (FGPM) and subjected to a rigid circular punch. It is found that, along the thickness direction, the electromechanical properties of FGPMs change exponentially. We apply the Hankel integral transform technique and reduce the problem to a singular integral equation, and then numerically determine the unknown contact stress and electric displacement at the contact surface. The results show that the surface contact stress, surface azimuthal displacement, surface electric displacement, and inner electromechanical field are obviously dependent on the gradient index of the FGPM coating. It is found that we can adjust the gradient index of the FGPM coating to modify the distributions of the electric displacement and contact stress.

  3. [Current quality management situation and administration countermeasure study of enterprises marketing corneal contact lens].

    PubMed

    Liu, Yungui; Yao, Ying; Shangguan, Shihao; Gu, Qun; Gao, Wuming; Chen, Yaoshui

    2014-05-01

    Study the current quality management situation of enterprises marketing corneal contact lens via systemic investigations and explore effective administration countermeasures in the future. The quality management indicators of sixty-two corneal contact lens marketing enterprises in Xuhui district of Shanghai were systematically investigated and enterprises of different operation models was compared and analyzed. Wholesale enterprises and retail chain enterprises are apparently better than independent enterprises almost in all facets. Facilitate market accession of corneal contact lens marketing enterprises, encourage the business model of retail chain, enhance supervision of corneal contact lens marketing enterprises, especially independent franchisors.

  4. Tunneling current of the contact between impurity-containing graphene nanoribbons

    SciTech Connect

    Belonenko, M. B.; Pak, A. V. Lebedev, N. G.

    2013-05-15

    The current-voltage characteristics of a tunneling contact between two graphene nanoribbons containing impurity atoms are obtained based on the previously calculated density of states. The dependences on the nanoribbon geometrical and energy characteristics are calculated.

  5. Coulomb frictional contact by explicit projection in the cone for finite displacement quasi-static problems

    NASA Astrophysics Data System (ADS)

    Areias, P.; Rabczuk, T.; de Melo, F. J. M. Queirós; de Sá, J. César

    2015-01-01

    We propose, in this paper, a distinct perspective on the solution of the Coulomb frictional contact problem. By combining the prediction/correction method for the contact force vector with the correction step being a cone projection and writing the friction cone surface in the quadratic form, we directly calculate the contact force. The distance along the friction cone normal is determined by solving a nonlinear problem in closed form. Numerical advantages of this projection are apparent for large values of friction coefficient. Six problems previously indicated as difficult to solve by the node-to-segment discretization and the operator split algorithm are here solved with the new projection algorithm. Discretization follows node-to segment and node-to-face derivations with gap vector defined in a global frame (without tangential and normal decomposition). In addition, we provide source codes for the 2D and 3D contact cases.

  6. Neurocysticercosis: Diagnostic problems & current therapeutic strategies

    PubMed Central

    Rajshekhar, Vedantam

    2016-01-01

    Neurocysticercosis (NCC) is the most common single cause of seizures/epilepsy in India and several other endemic countries throughout the world. It is also the most common parasitic disease of the brain caused by the cestode Taenia solium or pork tapeworm. The diagnosis of NCC and the tapeworm carrier (taeniasis) can be relatively inaccessible and expensive for most of the patients. In spite of the introduction of several new immunological tests, neuroimaging remains the main diagnostic test for NCC. The treatment of NCC is also mired in controversy although, there is emerging evidence that albendazole (a cysticidal drug) may be beneficial for patients by reducing the number of seizures and hastening the resolution of live cysts. Currently, there are several diagnostic and management issues which remain unresolved. This review will highlight some of these issues. PMID:28139530

  7. 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.

  8. Musculoskeletal problems in soccer players: current concepts.

    PubMed

    Longo, Umile Giuseppe; Loppini, Mattia; Cavagnino, Roberta; Maffulli, Nicola; Denaro, Vincenzo

    2012-05-01

    Soccer is the most popular sport worldwide, with about 200 million players, both professionals and amateurs. Because of its popularity, it has been often proposed to be able to prevent or cure health problems around the world. Although participation in football leads to significant physical benefits such as improving well-being, extending life expectancy and reducing the likelihood of several major non-communicable diseases, the possibility to incur in soccer injuries must be considered. On average, an elite football player suffers from 1.5-7.6 injuries each 1,000 hours of training and 12-35 injuries each 1000 hours of match. Several risk factors for soccer injuries have been described. The most important of them are the level of play (the risk appears to be higher in professional than amateur players); the exercise load; and the standard of training. The injury prevention program "The 11", developed with the support of the Federation Internationale de Football Association (FIFA), aims to reduce the impact of intrinsic injury risk factors in soccer, and it has been validated in that sport. A successive modified version of "The 11" ("The 11+") has been also shown to be effective in preventing injuries in young female soccer players. The FIFA 11+ provided more than 40% of reduction of the risk of injury. Several factors can be related to the risk of injury during sport. Therefore different exercises or factors might have been responsible for efficacy of the FIFA 11+ to prevent injuries. Several improvements have been surely achieved in the last ten years, but further investigation is needed to improve the benefits of playing soccer on human health.

  9. [The current approaches to chronic prostatitis problems].

    PubMed

    Maglakelidze, G M

    2009-11-01

    The current literature on mechanisms involved in the pathogenesis of prostatitis/chronic pelvic pain syndrome (CPPS) is reviewed. Based on the literature and own observation it is suggested that, in the pathogenesis of chronic prostatitis are involved several mechanisms, and the mechanism of infection, especially in the later stages of the disease, is not determinative. Author gives his views concerning the chronic prostatitis. He suggests that the disease is laid down by virus (or group of viruses) which exists in the cell during embryonic life. Lifelong effect of virus (or group of viruses) on cells may initiate different chronic inflammatory processes and different pathologic changes in the organism, including prostatitis. Analysis of the literature showed a lack of a complete understanding of the causes and mechanisms of chronic prostatitis, but it also showed that the prostatitis syndrome is no longer a faceless myth. It is a reality, and the new awareness of its importance may give new hope for patients suffering from this intractable pain syndrome Further research in this area will help to better understand the nature of chronic prostatitis and find the best possible solutions in its treatment.

  10. Self-reported contacts for mental health problems by rural residents: predicted service needs, facilitators and barriers.

    PubMed

    Handley, Tonelle E; Kay-Lambkin, Frances J; Inder, Kerry J; Lewin, Terry J; Attia, John R; Fuller, Jeffrey; Perkins, David; Coleman, Clare; Weaver, Natasha; Kelly, Brian J

    2014-09-06

    Rural and remote Australians face a range of barriers to mental health care, potentially limiting the extent to which current services and support networks may provide assistance. This paper examines self-reported mental health problems and contacts during the last 12 months, and explores cross-sectional associations between potential facilitators/barriers and professional and non-professional help-seeking, while taking into account expected associations with socio-demographic and health-related factors. During the 3-year follow-up of the Australian Rural Mental Health Study (ARMHS) a self-report survey was completed by adult rural residents (N = 1,231; 61% female; 77% married; 22% remote location; mean age = 59 years), which examined socio-demographic characteristics, current health status factors, predicted service needs, self-reported professional and non-professional contacts for mental health problems in the last 12 months, other aspects of help-seeking, and perceived barriers. Professional contacts for mental health problems were reported by 18% of the sample (including 14% reporting General Practitioner contacts), while non-professional contacts were reported by 16% (including 14% reporting discussions with family/friends). Perceived barriers to health care fell under the domains of structural (e.g., costs, distance), attitudinal (e.g., stigma concerns, confidentiality), and time commitments. Participants with 12-month mental health problems who reported their needs as met had the highest levels of service use. Hierarchical logistic regressions revealed a dose-response relationship between the level of predicted need and the likelihood of reporting professional and non-professional contacts, together with associations with socio-demographic characteristics (e.g., gender, relationships, and financial circumstances), suicidal ideation, and attitudinal factors, but not geographical remoteness. Rates of self-reported mental health problems were

  11. Unveiling Contacts within Macromolecular Assemblies by Solving Minimum Weight Connectivity Inference (MWC) Problems.

    PubMed

    Agarwal, Deepesh; Caillouet, Christelle; Coudert, David; Cazals, Frederic

    2015-08-01

    Consider a set of oligomers listing the subunits involved in subcomplexes of a macromolecular assembly, obtained e.g. using native mass spectrometry or affinity purification. Given these oligomers, connectivity inference (CI) consists of finding the most plausible contacts between these subunits, and minimum connectivity inference (MCI) is the variant consisting of finding a set of contacts of smallest cardinality. MCI problems avoid speculating on the total number of contacts but yield a subset of all contacts and do not allow exploiting a priori information on the likelihood of individual contacts. In this context, we present two novel algorithms, MILP-W and MILP-WB. The former solves the minimum weight connectivity inference (MWCI), an optimization problem whose criterion mixes the number of contacts and their likelihood. The latter uses the former in a bootstrap fashion to improve the sensitivity and the specificity of solution sets.Experiments on three systems (yeast exosome, yeast proteasome lid, human eIF3), for which reference contacts are known (crystal structure, cryo electron microscopy, cross-linking), show that our algorithms predict contacts with high specificity and sensitivity, yielding a very significant improvement over previous work, typically a twofold increase in sensitivity.The software accompanying this paper is made available and should prove of ubiquitous interest whenever connectivity inference from oligomers is faced.

  12. Serious Emotional and Behavioral Problems and Mental Health Contacts in American and British Children and Adolescents

    ERIC Educational Resources Information Center

    Mojtabai, Ramin

    2006-01-01

    Objective: To compare prevalence of serious emotional and behavioral problems and mental health contacts for these problems among American and British children and adolescents. Method: Data on children and adolescents ages 5 to 16 years were drawn from the 2004 U.S. National Health Interview Survey (response rate = 79.4%) and the 2004 survey of…

  13. Analytical solution of the contact problem for a system of bodies under collective wear

    NASA Astrophysics Data System (ADS)

    Soldatenkov, I. A.

    2017-01-01

    The contact problem is considered for a system of bodies subject to wear on a common base. The deformation properties of the bodies and the base are described by the Winkler model. The problem is reduced to a system of ordinary differential equations and an integral equation of hereditary type with difference kernel. The solution of the problem is constructed with the use of the Laplace transform. The asymptotics of the solution at large times is studied. The continuity conditions for the contact of each of the bodies with the base are derived.

  14. Evaluation of current densities and total contact currents in occupational exposure at 400 kV substations and power lines.

    PubMed

    Korpinen, Leena H; Elovaara, Jarmo A; Kuisti, Harri A

    2009-04-01

    This investigation studied the current densities in the neck and total contact currents in occupational exposure at 400 kV substations and power lines. Eight voluntary workers simulated their normal work tasks using the helmet-mask measuring system. In all, 151 work tasks with induced current measurements were made. Work situations were: tasks in 400 kV substations, tasks in 400-110 kV towers and the cutting of vegetation under 400 kV power lines. The average current density in the neck was estimated from the current induced in the helmet. The calculated maximum average current densities in the neck varied from 1.5 to 6.4 mA/m(2) and the maximum total contact currents from 66.8 to 458.4 microA. The study shows that the maximum average current densities and the total contact currents (caused by electric field) in occupational exposure at 400 kV substations and power lines does not exceed the limit and action values (10 mA/m(2) and 1 mA) of the new EU-directive 2004/40/EC (live-line bare-hand works excluded). (c) 2009 Wiley-Liss, Inc.

  15. Short-circuit current improvement in thin cells with a gridded back contact

    NASA Technical Reports Server (NTRS)

    Giuliano, M.; Wohlgemuth, J.

    1980-01-01

    The use of gridded back contact on thin silicon solar cells 50 micrometers was investigated. An unexpected increase in short circuit current of almost 10 percent was experienced for 2 cm x 2 cm cells. Control cells with the standard continuous contact metallization were fabricated at the same time as the gridded back cells with all processes identical up to the formation of the back contact. The gridded back contact pattern was delineated by evaporation of Ti-Pd over a photo-resist mask applied to the back of the wafer; the Ti-Pd film on the controls was applied in the standard fashion in a continuous layer over the back of the cell. The Ti-Pd contacts were similarly applied to the front of the wafer, and the grid pattern on both sides of the cell was electroplated with 8-10 micrometers of silver.

  16. Pilot measurements of ELF contact currents in some electric utility occupations.

    PubMed

    Bowman, Joseph; Niple, John; Kavet, Rob

    2006-06-01

    Contact currents from touching objects with different voltages can produce electric fields within the body that produce neurological and other biological effects. To begin measuring these exposures among electric utility workers, a new contact current meter (CCM) was tested in a pilot study at Southern California Edison. The CCM was worn for 82 full-shift measurements by 76 volunteers from eight occupations who did not work directly with energized electrical equipment. The volunteers were exposed to an average of 285.8 contact current events above the meter's 1-microA threshold, but most of these were electrostatic spark discharges. Fourteen employees experienced an average of 135.1 contact currents events whose primary frequency was 60 Hz. Using a circuit model of the human body, the average contact currents going from arm to arm was 9.8 microA (maximum = 178.0 microA), and the average going down the torso was 25.5 microA (maximum = 662.0). The maximum exposures were experienced by a technical support employee working in a substation. All measurements in this pilot study were below the 3000 microA maximum permissible exposure for contact currents set by the Institute of Electrical and Electronic Engineers (IEEE). Combining these current measurements with the results of high-resolution dosimetry, the internal electric fields averaged an estimated 1.7 mV/m in the heart (maximum = 21.0 mV/m), and 1.9 mV/m in the hematopoietic bone marrow in the torso (maximum = 56.5 mV/m). These internal electric fields from contact currents are below the basic restriction of 943 mV/m in the IEEE exposure standards but are above 1 mV/m, a level where biological effects have been often reported in laboratory studies. Safety concerns limited the measurements to de-energized equipment, so we did not obtain data on work in energized high-voltage environments, the most likely sources of high contact currents. This pilot study identified other improvements to the contact current meter that

  17. General framework for dynamic large deformation contact problems based on phantom-node X-FEM

    NASA Astrophysics Data System (ADS)

    Broumand, P.; Khoei, A. R.

    2017-08-01

    This paper presents a general framework for modeling dynamic large deformation contact-impact problems based on the phantom-node extended finite element method. The large sliding penalty contact formulation is presented based on a master-slave approach which is implemented within the phantom-node X-FEM and an explicit central difference scheme is used to model the inertial effects. The method is compared with conventional contact X-FEM; advantages, limitations and implementational aspects are also addressed. Several numerical examples are presented to show the robustness and accuracy of the proposed method.

  18. A Jacobian-Free Newton Krylov Method for Mortar-Discretized Thermomechanical Contact Problems

    SciTech Connect

    Glen Hansen

    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 reactor fuel rod, which consists of cylindrical pellets of uranium dioxide (UO2) 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.

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

    SciTech Connect

    Hansen, Glen

    2011-07-20

    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{sub 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.

  20. 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.

  1. Contact and crack problems for an elastic wedge. [stress concentration in elastic half spaces

    NASA Technical Reports Server (NTRS)

    Erdogan, F.; Gupta, G. D.

    1974-01-01

    The contact and the crack problems for an elastic wedge of arbitrary angle are considered. The problem is reduced to a singular integral equation which, in the general case, may have a generalized Cauchy kernel. The singularities under the stamp as well as at the wedge apex were studied, and the relevant stress intensity factors are defined. The problem was solved for various wedge geometries and loading conditions. The results may be applicable to certain foundation problems and to crack problems in symmetrically loaded wedges in which cracks initiate from the apex.

  2. History-Dependent Problems with Applications to Contact Models for Elastic Beams

    SciTech Connect

    Bartosz, Krzysztof; Kalita, Piotr; Migórski, Stanisław; Ochal, Anna; Sofonea, Mircea

    2016-02-15

    We prove an existence and uniqueness result for a class of subdifferential inclusions which involve a history-dependent operator. Then we specialize this result in the study of a class of history-dependent hemivariational inequalities. Problems of such kind arise in a large number of mathematical models which describe quasistatic processes of contact. To provide an example we consider an elastic beam in contact with a reactive obstacle. The contact is modeled with a new and nonstandard condition which involves both the subdifferential of a nonconvex and nonsmooth function and a Volterra-type integral term. We derive a variational formulation of the problem which is in the form of a history-dependent hemivariational inequality for the displacement field. Then, we use our abstract result to prove its unique weak solvability. Finally, we consider a numerical approximation of the model, solve effectively the approximate problems and provide numerical simulations.

  3. 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

  4. Criminal Justice Contact, Stressors, and Obesity-Related Health Problems Among Black Adults in the USA.

    PubMed

    Archibald, Paul C; Parker, Lauren; Thorpe, Roland

    2017-06-08

    Criminal justice contact-defined as lifetime arrest, parole, or incarceration, seems to exacerbate chronic conditions, and those who are most likely to have had contact with the criminal justice system, such as Black adults, often already have pre-existing disproportionately high rates of stress and chronic conditions due to the social determinants of health that affect underrepresented minorities. Findings from this study suggest that there is a mechanism that links the stressors among Black adults manifested by such factors as family, financial, neighborhood, and personal problems with criminal justice contact to obesity-related health status. Using the National Survey of American Life (NSAL), modified Poisson regression analyses were used to determine the association between criminal justice contact, stressors, and obesity-related health problems among a national sample of Black adults (n = 5008). In the full model, the odds of experiencing obesity-related health problems for Black adults who had criminal justice contact was reduced (PR, 1.23 to 1.14) and not statistically significant. Black adults who reported experiencing family stressors (PR, 1.21; 95% CI, 1.08, 1.36), financial stressors (PR, 1.30; 95% CI, 1.16, 1.47), and personal stressors (PR, 1.16; 95% CI, 1.02, 1.31) were statistically significant and higher than those who reported not experiencing any of these stressors; neighborhood stressors was not statistically significant. The evidence suggests a relationship between the stressors associated with criminal justice contact and obesity-related health status. These findings emphasize the need to further explore the family, financial, and personal stressors for Black adults with criminal justice contact in order to further our understanding of their obesity-related health problems.ᅟ.

  5. Equipment grounding affects contact current exposure: a case study of sewing machines.

    PubMed

    Niple, John C; Sahl, Jack D; Kelsh, Michael A; Kavet, Robert

    2005-11-01

    Exposure to contact current may occur when the body is in contact with two conductive surfaces with different electrical potentials. To date, no published data that describe such exposures or electrical conditions that may predispose to such exposures exist. Our investigation into contact current exposure included (i) a small sample of workers in a garment production facility with modern well-grounded equipment performing normal work tasks and (ii) a single individual simulating garment production tasks in a sewing machine repair facility with substandard equipment grounding. In both cases, we deployed a newly developed personal monitor that records contact current events at the power frequency of 60 Hz. The personal monitoring data suggested that more frequent exposure occurs in association with, and probably because of, poorer grounding practices. This preliminary conclusion was validated with controlled laboratory measurements of potentials to reference ground on specific locations of four sewing machines with different grounding characteristics. Propensity to exposure was greater in the two machines with inferior grounding characteristics, and increased in the other two when deprived of their grounding connections. Contact currents at or below threshold-of-perception levels can produce electric fields within tissues that may plausibly produce biological effects. On this basis, such exposures have been under-investigated relative to the far greater attention accorded to occupational electric and magnetic fields.

  6. From the Nano- to the Macroscale - Bridging Scales for the Moving Contact Line Problem

    NASA Astrophysics Data System (ADS)

    Nold, Andreas; Sibley, David; Goddard, Benjamin; Kalliadasis, Serafim; Complex Multiscale Systems Team

    2016-11-01

    The moving contact line problem remains an unsolved fundamental problem in fluid mechanics. At the heart of the problem is its multiscale nature: a nanoscale region close to the solid boundary where the continuum hypothesis breaks down, must be resolved before effective macroscale parameters such as contact line friction and slip can be obtained. To capture nanoscale properties very close to the contact line and to establish a link to the macroscale behaviour, we employ classical density-functional theory (DFT), in combination with extended Navier-Stokes-like equations. Using simple models for viscosity and slip at the wall, we compare our computations with the Molecular Kinetic Theory, by extracting the contact line friction, depending on the imposed temperature of the fluid. A key fluid property captured by DFT is the fluid layering at the wall-fluid interface, which has a large effect on the shearing properties of a fluid. To capture this crucial property, we propose an anisotropic model for the viscosity, which also allows us to scrutinize the effect of fluid layering on contact line friction.

  7. 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.

  8. Current crowding mediated large contact noise in graphene field-effect transistors

    NASA Astrophysics Data System (ADS)

    Karnatak, Paritosh; Sai, T. Phanindra; Goswami, Srijit; Ghatak, Subhamoy; Kaushal, Sanjeev; Ghosh, Arindam

    2016-12-01

    The impact of the intrinsic time-dependent fluctuations in the electrical resistance at the graphene-metal interface or the contact noise, on the performance of graphene field-effect transistors, can be as adverse as the contact resistance itself, but remains largely unexplored. Here we have investigated the contact noise in graphene field-effect transistors of varying device geometry and contact configuration, with carrier mobility ranging from 5,000 to 80,000 cm2 V-1 s-1. Our phenomenological model for contact noise because of current crowding in purely two-dimensional conductors confirms that the contacts dominate the measured resistance noise in all graphene field-effect transistors in the two-probe or invasive four-probe configurations, and surprisingly, also in nearly noninvasive four-probe (Hall bar) configuration in the high-mobility devices. The microscopic origin of contact noise is directly linked to the fluctuating electrostatic environment of the metal-channel interface, which could be generic to two-dimensional material-based electronic devices.

  9. Current crowding mediated large contact noise in graphene field-effect transistors

    PubMed Central

    Karnatak, Paritosh; Sai, T. Phanindra; Goswami, Srijit; Ghatak, Subhamoy; Kaushal, Sanjeev; Ghosh, Arindam

    2016-01-01

    The impact of the intrinsic time-dependent fluctuations in the electrical resistance at the graphene–metal interface or the contact noise, on the performance of graphene field-effect transistors, can be as adverse as the contact resistance itself, but remains largely unexplored. Here we have investigated the contact noise in graphene field-effect transistors of varying device geometry and contact configuration, with carrier mobility ranging from 5,000 to 80,000 cm2 V−1 s−1. Our phenomenological model for contact noise because of current crowding in purely two-dimensional conductors confirms that the contacts dominate the measured resistance noise in all graphene field-effect transistors in the two-probe or invasive four-probe configurations, and surprisingly, also in nearly noninvasive four-probe (Hall bar) configuration in the high-mobility devices. The microscopic origin of contact noise is directly linked to the fluctuating electrostatic environment of the metal–channel interface, which could be generic to two-dimensional material-based electronic devices. PMID:27929087

  10. Contact problems for a circular plate with sliding fixation at the end face

    NASA Astrophysics Data System (ADS)

    Bazarenko, N. A.

    2014-05-01

    Two mixed elasticity problems of punch indentation into a circular plate placed without clearance in a rigid cylindrical holder with smooth walls are considered. In the first problem, the plate lies without friction on a rigid base, and in the second problem, the plate is rigidly fixed to the base. The problems are solved by a method that was developed for bodies of finite dimensions and is based on the properties of closed systems of orthogonal functions. Each of the problems is reduced to two integral equations, namely, a Volterra integral equation of the first kind for the contact pressure function and a Fredholm integral equation of the first kind for the derivatives of the displacement of the plate upper surface outside the punch. The displacement function is sought as the sum of a trigonometric series and a power function with a root singularity. After truncation, the obtained illposed system of linear algebraic equation has a stable solution. A method for solving Volterra integral equations is given. The contact pressure distribution function and the dimensionless indentation force are determined. Examples of calculation of the plate interaction with the plane punch are given. Contact problems were earlier studied for a rectangle and a circular plate with a stress-free end both without taking account of their fixation [1, 2] and with regard for their fixation [3, 4]. The solution method described here was used to study the interaction of elastic hollow cylinder of finite length with a rigid bandage and a rigid insert [5, 6]. Other papers dealing with contact problems for bodies of finite dimensions, in particular, for a circular plate, should also be mentioned. In these papers, the problems under study were solved by the method of homogeneous solutions [7, 8] and by the method of coupled series-equations [9].

  11. The JKR-type adhesive contact problems for power-law shaped axisymmetric punches

    NASA Astrophysics Data System (ADS)

    Borodich, Feodor M.; Galanov, Boris A.; Suarez-Alvarez, Maria M.

    2014-08-01

    The JKR (Johnson, Kendall, and Roberts) and Boussinesq-Kendall models describe adhesive frictionless contact between two isotropic elastic spheres, and between a flat-ended axisymmetric punch and an elastic half-space respectively. However, the shapes of contacting solids may be more general than spherical or flat ones. In addition, the derivation of the main formulae of these models is based on the assumption that the material points within the contact region can move along the punch surface without any friction. However, it is more natural to assume that a material point that came to contact with the punch sticks to its surface, i.e. to assume that the non-slipping boundary conditions are valid. It is shown that the frictionless JKR model may be generalized to arbitrary convex, blunt axisymmetric body, in particular to the case of the punch shape being described by monomial (power-law) punches of an arbitrary degree d≥1. The JKR and Boussinesq-Kendall models are particular cases of the problems for monomial punches, when the degree of the punch d is equal to two or it goes to infinity respectively. The generalized problems for monomial punches are studied under both frictionless and non-slipping (or no-slip) boundary conditions. It is shown that regardless of the boundary conditions, the solution to the problems is reduced to the same dimensionless relations among the actual force, displacements and contact radius. The explicit expressions are derived for the values of the pull-off force and for the corresponding critical contact radius. Connections of the results obtained for problems of nanoindentation in the case of the indenter shape near the tip has some deviation from its nominal shape and the shape function can be approximated by a monomial function of radius, are discussed.

  12. Contact of boundary-value problems and nonlocal problems in mathematical models of heat transfer

    NASA Astrophysics Data System (ADS)

    Lyashenko, V.; Kobilskaya, O.

    2015-10-01

    In this paper the mathematical models in the form of nonlocal problems for the two-dimensional heat equation are considered. Relation of a nonlocal problem and a boundary value problem, which describe the same physical heating process, is investigated. These problems arise in the study of the temperature distribution during annealing of the movable wire and the strip by permanent or periodically operating internal and external heat sources. The first and the second nonlocal problems in the mobile area are considered. Stability and convergence of numerical algorithms for the solution of a nonlocal problem with piecewise monotone functions in the equations and boundary conditions are investigated. Piecewise monotone functions characterize the heat sources and heat transfer conditions at the boundaries of the area that is studied. Numerous experiments are conducted and temperature distributions are plotted under conditions of internal and external heat sources operation. These experiments confirm the effectiveness of attracting non-local terms to describe the thermal processes. Expediency of applying nonlocal problems containing nonlocal conditions - thermal balance conditions - to such models is shown. This allows you to define heat and mass transfer as the parameters of the process control, in particular heat source and concentration of the substance.

  13. Superior Current Carrying Capacity of Boron Nitride Encapsulated Carbon Nanotubes with Zero-Dimensional Contacts.

    PubMed

    Huang, Jhao-Wun; Pan, Cheng; Tran, Son; Cheng, Bin; Watanabe, Kenji; Taniguchi, Takashi; Lau, Chun Ning; Bockrath, Marc

    2015-10-14

    We report fabrication and characterization of hexagonal boron nitride (hBN)-encapsulated carbon nanotube (CNT) field effect transistors, which are coupled to electrical leads via zero-dimensional contacts. Device quality is attested by the ohmic contacts and observation of Coulomb blockade with a single periodicity in small bandgap semiconducing nanotubes. Surprisingly, hBN-encapsulated CNT devices demonstrate significantly enhanced current carrying capacity; a single-walled CNT can sustain >180 μA current or, equivalently, a current density of ∼2 × 10(10) A/cm(2), which is a factor of 6-7 higher than devices supported on SiO2 substrates. Such dramatic enhancement of current carrying capacity arises from the high thermal conductivity of hBN and lower hBN-CNT interfacial thermal resistance and has implications for carbon electronic applications.

  14. Influence of the thermal contact resistance in current-induced domain wall depinning

    NASA Astrophysics Data System (ADS)

    López, Cristina; Ramos, Eduardo; Muñoz, Manuel; Kar-Narayan, S.; Mathur, N. D.; Prieto, José L.

    2017-08-01

    In this work we study the influence of the thermal contact resistance on the temperature of a typical nanostripe used in current induced magnetic domain wall movement or depinning. The thermal contact resistance arises from an imperfect heat transport across the interface between the metallic ferromagnetic nanostripe and the substrate. We show that this parameter, which is likely non-zero in any experimental device, increases the temperature in the nanostripe considerably. When the current is injected in the nanostripe in nanosecond long pulses, the larger temperature also implies a reduction of the effective current density delivered by the pulse generator. Both the thermal contact resistance and the dynamic response of the pulse generator are usually neglected in theoretical estimations of the influence of spin transfer torque on domain wall displacement and depinning. Here we show that only if the thermal contact resistance and the electric resistivity of the ferromagnetic nanostripe are optimized to the best values reported in the bibliography, the Joule heating may not be so crucial for current densities of the order of 108 A cm-2. Also, the use of physical constrictions (notch) to pin the magnetic domain wall may complicate the interpretation of the results as they always come together with relevant thermal gradients.

  15. 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.

  16. 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.

  17. Contact problem with wear for a foundation with a surface nonuniform coating

    NASA Astrophysics Data System (ADS)

    Manzhirov, A. V.; Kazakov, K. E.

    2017-07-01

    The plane contact problem with wear for an elastic foundation with a longitudinally nonuniform (surface nonuniform) coating and a rigid punch with a flat foundation has been solved for the first time. The case of linear wear is considered. The nonuniformity of the coating is described by a rapidly changing function. This strong nonuniformity arises when coatings are deposited using modern additive manufacturing technologies. The problem is reduced to the solution of an integral equation with two different integral operators: a compact self-adjoint positively defined operator with respect to the coordinate and the non-selfadjoint integral Volterra operator with respect to time. The solution is obtained in series using author's projection method. The efficiency of the proposed approach for constructing a high-accuracy approximate solution to the problem (with only a few expansion terms retained) is demonstrated. A simple engineering formula for estimating the contact stresses under a punch for large values of times is proposed.

  18. A fast nonlinear conjugate gradient based method for 3D concentrated frictional contact problems

    NASA Astrophysics Data System (ADS)

    Zhao, Jing; Vollebregt, Edwin A. H.; Oosterlee, Cornelis W.

    2015-05-01

    This paper presents a fast numerical solver for a nonlinear constrained optimization problem, arising from 3D concentrated frictional shift and rolling contact problems with dry Coulomb friction. The solver combines an active set strategy with a nonlinear conjugate gradient method. One novelty is to consider the tractions of each slip element in a polar coordinate system, using azimuth angles as variables instead of conventional traction variables. The new variables are scaled by the diagonal of the underlying Jacobian. The fast Fourier transform (FFT) technique accelerates all matrix-vector products encountered, exploiting the matrix' Toeplitz structure. Numerical tests demonstrate a significant reduction of the computational time compared to existing solvers for concentrated contact problems.

  19. A Lagrange Multiplier/Segment Procedure for Solution of Three-Dimensional Contact Problems

    DTIC Science & Technology

    1985-10-01

    AtX (i-1) = current global coordinates of node k after 4 iteration (i-1) for the equilibrium configuration corresponding to time t+At t+ atAk (1.1...contact, the incremental displacements in iteration (i) are such that (see Fig. 4) 9 the material overlap, t+ AtAk is eliminated * the physical point

  20. The Crack-contact and the Free End Problem for a Strip Under Residual Stress

    NASA Technical Reports Server (NTRS)

    Bakioglu, M.; Erdogan, F.

    1976-01-01

    The plane problem for an infinite strip with two edge cracks under a given state of residual stress is considered. The residual stress is compressive near and at the surfaces and tensile in the interior of the strip. If the crack is deep enough to penetrate into the tensile zone, then the problem is one of crack-contact problem in which the depth of the contact area is an unknown which depends on the crack depth and the residual stress profile. The problem has applications to the static fatigue of glass plates and is solved for three typical residual stress profiles. In the limiting case of the crack crossing the entire plate thickness, the problem becomes a stress-free end problem for a semi-infinite strip under a given residual stress state away from the end. This is a typical stress diffusion problem in which decay behavior of the residual stress near and the nature of the normal displacement at the end of the semi-infinite strip are of special interest. For two typical residual stress states the solution is obtained, and some numerical results are given.

  1. 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.

  2. 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

    2009-09-02

    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.

  3. Inverse problem in nondestructive testing using arrayed eddy current sensors.

    PubMed

    Zaoui, Abdelhalim; Menana, Hocine; Feliachi, Mouloud; Berthiau, Gérard

    2010-01-01

    A fast crack profile reconstitution model in nondestructive testing is developed using an arrayed eddy current sensor. The inverse problem is based on an iterative solving of the direct problem using genetic algorithms. In the direct problem, assuming a current excitation, the incident field produced by all the coils of the arrayed sensor is obtained by the translation and superposition of the 2D axisymmetric finite element results obtained for one coil; the impedance variation of each coil, due to the crack, is obtained by the reciprocity principle involving the dyadic Green's function. For the inverse problem, the surface of the crack is subdivided into rectangular cells, and the objective function is expressed only in terms of the depth of each cell. The evaluation of the dyadic Green's function matrix is made independently of the iterative procedure, making the inversion very fast.

  4. 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.

  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. 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.

  7. 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.

  8. 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

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

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

    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 [1] 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 [2] 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

  10. 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.

  11. Analytical model development of an eddy-current-based non-contacting steel plate conveyance system

    NASA Astrophysics Data System (ADS)

    Liu, Cheng-Tsung; Lin, Sheng-Yang; Yang, Yung-Yi; Hwang, Chang-Chou

    A concise model for analyzing and predicting the quasi-static electromagnetic characteristics of an eddy-current-based non-contacting steel plate conveyance system has been developed. Confirmed by three-dimensional (3-D) finite element analysis (FEA), adequacy of the analytical model can be demonstrated. Such an effective approach, which can be conveniently used by the potential industries for preliminary system operational performance evaluations, will be essential for designers and on-site engineers.

  12. 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

  13. 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…

  14. 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)…

  15. Capacity Building for School Development: Current Problems and Future Challenges

    ERIC Educational Resources Information Center

    Ho, Dora; Lee, Moosung

    2016-01-01

    This article offers a theoretical discussion on the current problems and future challenges of school capacity building in early childhood education (ECE), aiming to highlight some key areas for future research. In recent years, there has been a notable policy shift from monitoring quality through inspection to improving quality through school…

  16. [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.

  17. 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…

  18. Capacity Building for School Development: Current Problems and Future Challenges

    ERIC Educational Resources Information Center

    Ho, Dora; Lee, Moosung

    2016-01-01

    This article offers a theoretical discussion on the current problems and future challenges of school capacity building in early childhood education (ECE), aiming to highlight some key areas for future research. In recent years, there has been a notable policy shift from monitoring quality through inspection to improving quality through school…

  19. MEG forward problem formulation using equivalent surface current densities.

    PubMed

    von Ellenrieder, Nicolás; Muravchik, Carlos H; Nehorai, Arye

    2005-07-01

    We present a formulation for the magnetoencephalography (MEG) forward problem with a layered head model. Traditionally the magnetic field is computed based on the electric potential on the interfaces between the layers. We propose to express the effect of the volumetric currents in terms of an equivalent surface current density on each interface, and obtain the magnetic field based on them. The boundary elements method is used to compute the equivalent current density and the magnetic field for a realistic head geometry. We present numerical results showing that the MEG forward problem is solved correctly with this formulation, and compare it with the performance of the traditional formulation. We conclude that the traditional formulation generally performs better, but still the new formulation is useful in certain situations.

  20. An approach to ERO problem in displacement eddy current sensor

    NASA Astrophysics Data System (ADS)

    Yu, Yating; Tian, Guiyun; Li, Xinhua; Simm, Anthony

    2013-09-01

    Eddy current (EC) sensors are widely applied in displacement (proximity) measurement as well as nondestructive testing and evaluation for defect detection or material characterisation. For displacement measurement, one of the research aims is to overcome measurement uncertainties due to material variation and inhomogeneity. This problem is called as electrical runout (ERO) problem. In this paper, an approach to ERO problem is presented based on the coaxial ellipse distribution (CED) pattern of the EC sensor. In the CED pattern, the real and the imaginary parts of the magnetic flux density in the z-component (B z ), with the variation of the sample conductivity under the different lift-offs, are located on an ellipse curve. Furthermore, the CED pattern is verified by the different sensor specifications, such as excitation frequency and probe coil geometry. According to the CED pattern, the ERO problem in EC sensors can be overcome well when the sample is magnetised to saturation.

  1. 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.

  2. Soldered contact and current risetime effects on negative polarity wire array Z pinches

    NASA Astrophysics Data System (ADS)

    Chalenski, D. A.; Kusse, B. R.; Greenly, J. B.

    2009-08-01

    The experimental results described in this paper were motivated by earlier, low current, single wire experiments. In these experiments, single 10-25 μm diameter wires were driven by 1-5 kA current pulses with variable dI /dt from 5 to 60 A/ns. The amount of energy deposited in the wires, the expansion rate, and expansion uniformity that occurred before a plasma induced voltage collapse were found to depend on the polarity, dI /dt, and the quality of the contacts between the wires and the electrodes. This paper reports the results of experiments with cylindrical wire arrays driven by Cornell Beam Research Accelerator (COBRA) [J. B. Greenly, J. D. Douglas, D. A. Hammer et al., Rev. Sci. Instrum. 79, 073501 (2008)] current pulses that reached 1 MA. The pulse lengths were varied from 100 to 200 ns. These larger current pulses drove the wires of the array through the initiation phase studied in the single wire experiments and through ablation and Z-pinch implosion to stagnation on the cylindrical axis of the array. Regardless of the current pulse length, the COBRA dI /dt per wire during initiation reached approximately 175 A/ns and resistive voltage breakdown occurred at ˜13 ns. Wire-electrode contacts were modified by soldering the cathode ends of the wires to the brass electrode. With the 100 ns COBRA pulse, voltage monitor data suggested that soldering produced a smaller radius pinch, but bolometer data showed that this did not affect the total energy emitted from the array compared to nonsoldered contacts. With the 200 ns COBRA pulse and soldered contacts, the bolometer data showed an average of 69% increase in time integrated x-ray emission and the photoconducting detector data showed an increase in x-ray power and yield compared with nonsoldered contacts. Under these same conditions the four-frame extreme ultraviolet images showed a more pronounced "Christmas tree" effect at the cathode.

  3. 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. © 2016 The Authors. Bioelectromagnetics published by Wiley Periodicals, Inc.

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

    PubMed Central

    Kuisti, Harri; Elovaara, Jarmo

    2016-01-01

    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/m2 (calculated internal EFs 5.0–12.0 mV/m), and the average values were 0.2–0.4 mA/m2. 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. PMID:27192179

  5. On the numerical solution of the dynamically loaded hydrodynamic lubrication of the point contact problem

    NASA Technical Reports Server (NTRS)

    Lim, Sang G.; Brewe, David E.; Prahl, Joseph M.

    1990-01-01

    The transient analysis of hydrodynamic lubrication of a point-contact is presented. A body-fitted coordinate system is introduced to transform the physical domain to a rectangular computational domain, enabling the use of the Newton-Raphson method for determining pressures and locating the cavitation boundary, where the Reynolds boundary condition is specified. In order to obtain the transient solution, an explicit Euler method is used to effect a time march. The transient dynamic load is a sinusoidal function of time with frequency, fractional loading, and mean load as parameters. Results include the variation of the minimum film thickness and phase-lag with time as functions of excitation frequency. The results are compared with the analytic solution to the transient step bearing problem with the same dynamic loading function. The similarities of the results suggest an approximate model of the point contact minimum film thickness solution.

  6. 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.

  7. 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.

  8. A non-invasive implementation of a mixed domain decomposition method for frictional contact problems

    NASA Astrophysics Data System (ADS)

    Oumaziz, Paul; Gosselet, Pierre; Boucard, Pierre-Alain; Guinard, Stéphane

    2017-07-01

    A non-invasive implementation of the Latin domain decomposition method for frictional contact problems is described. The formulation implies to deal with mixed (Robin) conditions on the faces of the subdomains, which is not a classical feature of commercial software. Therefore we propose a new implementation of the linear stage of the Latin method with a non-local search direction built as the stiffness of a layer of elements on the interfaces. This choice enables us to implement the method within the open source software Code_Aster, and to derive 2D and 3D examples with similar performance as the standard Latin method.

  9. Voltage tuning of thermal spin current in ferromagnetic tunnel contacts to semiconductors

    NASA Astrophysics Data System (ADS)

    Jeon, Kun-Rok; Min, Byoung-Chul; Spiesser, Aurelie; Saito, Hidekazu; Shin, Sung-Chul; Yuasa, Shinji; Jansen, Ron

    2014-04-01

    Spin currents are paramount to manipulate the magnetization of ferromagnetic elements in spin-based memory, logic and microwave devices, and to induce spin polarization in non-magnetic materials. A unique approach to create spin currents employs thermal gradients and heat flow. Here we demonstrate that a thermal spin current can be tuned conveniently by a voltage. In magnetic tunnel contacts to semiconductors (silicon and germanium), it is shown that a modest voltage (~200 mV) changes the thermal spin current induced by Seebeck spin tunnelling by a factor of five, because it modifies the relevant tunnelling states and thereby the spin-dependent thermoelectric parameters. The magnitude and direction of the spin current is also modulated by combining electrical and thermal spin currents with equal or opposite sign. The results demonstrate that spin-dependent thermoelectric properties away from the Fermi energy are accessible, and open the way towards tailoring thermal spin currents and torques by voltage, rather than material design.

  10. 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.

  11. 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.

  12. Current research on food contact materials undertaken by the UK Ministry of Agriculture, Fisheries and Food.

    PubMed

    Gilbert, J; Castle, L; Jickells, S M; Sharman, M

    1994-01-01

    Recent research funded by the UK Ministry of Agriculture, Fisheries and Food (MAFF) in the area of migration from food contact materials is reviewed and set within a framework of surveillance; evaluation of new technology; support of current regulations; and anticipation of future controls. Recent surveillance projects monitoring foods for migration of monomeric plasticizers (in particular di-(2-ethylhexyl)adipate), polymeric additives and mineral hydrocarbons are highlighted. Development of high temperature testing conditions for food contact materials has been carried out in support of regulations and proposals are made for the control of susceptors by analysis of release of volatiles. Migration of benzophenone from the printing ink of a paper board sleeve during microwave heating of a pre-cooked meal is described as a recent example of a migration situation that would not easily have been anticipated. Finally, the approach being adopted for investigating paper and board food contact materials for inorganic constituents, for volatile organic and for solvent-extractable organic components is outlined as an example of work being carried out in anticipation of future regulatory controls.

  13. 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

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

    PubMed

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

    2016-04-01

    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 risk factor or cancer screening need were randomly assigned to one of three health referral interventions: verbal referrals only, verbal referrals + a tailored mailed reminder, or verbal referrals + telephone health navigator. After 1 month, we assessed whether the nonhealth problems that prompted the 2-1-1 call had been resolved. Logistic regression estimated effects of having the problem resolved on calling a health referral. Callers were predominantly female (85%) and had a high school education or less (61%); nearly half (47%) had incomes under $10,000. The most common service requests were for utility assistance (35%), home/family problems (23%), and rent/mortgage assistance (12%). At follow-up, 38% of callers reported that all problems prompting their 2-1-1 call had been resolved, and 24% reported calling a health referral. Resolving all problems prompting the 2-1-1 call was associated with a higher odds of contacting a health referral (odds ratio = 1.44, 95% confidence interval [1.02, 2.05]) compared to people whose problems were not resolved. Multifaceted interventions that help meet non-health-related needs and provide support in reaching health-related goals may promote health in vulnerable populations. © 2015 Society for Public Health Education.

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

    PubMed Central

    Thompson, Tess; Kreuter, Matthew; 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=1090) with at least one behavioral risk factor or cancer screening need were randomly assigned to one of three health referral interventions: verbal referrals only, verbal referrals + a tailored mailed reminder, or verbal referrals + telephone health navigator. After one month, we assessed whether the non-health problems that prompted the 2-1-1 call had been resolved. Logistic regression estimated effects of having the problem resolved on calling a health referral. Callers were predominantly female (85%) and had a high school education or less (61%); nearly half (47%) had incomes under $10,000. The most common service requests were for utility assistance (35%), home/family problems (23%), and rent/mortgage assistance (12%). At follow-up, 38% of callers reported that all problems prompting their 2-1-1 call had been resolved, and 24% reported calling a health referral. Resolving all problems prompting the 2-1-1 call was associated with a higher odds of contacting a health referral (OR = 1.44, 95% CI 1.02-2.05) compared to people whose problems were not resolved. Multifaceted interventions that help meet non-health-related needs and provide support in reaching health-related goals may promote health in vulnerable populations. PMID:26293458

  16. Current Health-Related Quality of Life in Former National Collegiate Athletic Association Division I Collision Athletes Compared With Contact and Limited-Contact Athletes.

    PubMed

    Simon, Janet E; Docherty, Carrie L

    2016-03-01

    Previous researchers have shown that current health-related quality of life (HRQoL) is lower in former National Collegiate Athletic Association Division I athletes than in nonathletes. However, evidence supports the idea that individuals in collision sports (football) may suffer more serious injuries that may affect them later in life. To measure HRQoL in former Division I collision, contact, and limited-contact athletes. Cross-sectional study. Research laboratory. A total of 374 former Division I athletes between the ages of 40 and 65 years were separated into collision, contact, and limited-contact groups. All individuals completed the Short Form 36 version 2 via a computer. The dependent variables were the physical component and mental component summary scores and the physical functioning, physical role functioning, bodily pain, general health, vitality, social role functioning, emotional role functioning, and mental health scales. An initial multivariate analysis of covariance included data from the 2 domains: physical component and mental component summary scores. The second multivariate analysis of covariance included data from the 8 dimensions: physical function, role physical, bodily pain scale, general health, mental health, role emotional, social function, and vitality scales. The α level was set at P < .05 with a covariate of sex. The responses were significantly lower (worse) for the former collision athletes compared with the contact and limited-contact athletes for the summary scores (F2,370 = 90.09, P < .01) and all 8 scales (F8,364 = 24.33, P < .01). The largest differences were between the collision and limited-contact athletes for the bodily pain and role physical scales, with mean differences of 12.91 and 11.80 points, respectively. Competing at the Division I level can be strenuous on an athlete's physical, mental, and social dimensions, which can affect the athlete later in life. Based on these data, collision athletes may sacrifice their

  17. The inverse problem for definition of the shape of a molten contact bridge

    NASA Astrophysics Data System (ADS)

    Kharin, Stanislav N.; Sarsengeldin, Merey M.

    2017-09-01

    The paper presents the results of investigation of bridging phenomenon occurring at opening of electrical contacts. The mathematical model describing the dynamics of metal molten bridge takes into account the Thomson effect. It is based on the system of partial differential equations for temperature and electrical fields of the bridge in the domain containing two moving unknown boundaries. One of them is an interface between liquid and solid zones of the bridge and should be found by the solution of the corresponding Stefan problem. The second free boundary corresponds to the shape of the visible part of a bridge. Its definition is an inverse problem, for which solution it is necessary to find minimum of the energy consuming for the formation of the shape of a quasi-stationary bridge. Three components of this energy, namely surface tension, pinch effect and gravitation, are defined by the functional which minimum gives the required shape of the bridge. The solution of corresponding variation problem is found by the reduction of the problem to the solution of the system of ordinary differential equations. Calculated values of the voltage of the bridge rupture for various metals are in a good agreement with the experimental data. The criteria responsible for the mechanism of molten bridge rupture are introduced in the paper.

  18. China's natural wetlands: past problems, current status, and future challenges.

    PubMed

    An, Shuqing; Li, Harbin; Guan, Baohua; Zhou, Changfang; Wang, Zhongsheng; Deng, Zifa; Zhi, Yingbiao; Liu, Yuhong; Xu, Chi; Fang, Shubo; Jiang, Jinhui; Li, Hongli

    2007-06-01

    Natural wetlands, occupying 3.8% of China's land and providing 54.9% of ecosystem services, are unevenly distributed among eight wetland regions. Natural wetlands in China suffered great loss and degradation (e.g., 23.0% freshwater swamps, 51.2% costal wetlands) because of the wetland reclamation during China's long history of civilization, and the population pressure and the misguided policies over the last 50 years. Recently, with an improved understanding that healthy wetland ecosystems play a vital role in her sustainable economic development, China started major efforts in wetland conservation, as signified by the policy to return reclaimed croplands to wetlands, the funding of billions of dollars to restore degraded wetlands, and the national plan to place 90% of natural wetlands under protection by 2030. This paper describes the current status of the natural wetlands in China, reviews past problems, and discusses current efforts and future challenges in protecting China's natural wetlands.

  19. Intrahepatic cholestasis of pregnancy-current achievements and unsolved problems

    PubMed Central

    Kondrackiene, Jurate; Kupcinskas, Limas

    2008-01-01

    Intrahepatic cholestasis of pregnancy (ICP) is the most common pregnancy-related liver disorder. Maternal effects of ICP are mild; however, there is a clear association between ICP and higher frequency of fetal distress, preterm delivery, and sudden intrauterine fetal death. The cause of ICP remains elusive, but there is evidence that mutations in genes encoding hepatobiliary transport proteins can predispose for the development of ICP. Recent data suggest that ursodeoxycholic acid is currently the most effective pharmacologic treatment, whereas obstetric management is still debated. Clinical trials are required to identify the most suitable monitoring modalities that can specifically predict poor perinatal outcome. This article aims to review current achievements and unsolved problems of ICP. PMID:18855975

  20. Problem of the length of the current interglacial

    NASA Astrophysics Data System (ADS)

    Dergachev, V. A.; Raspopov, O. M.

    2013-12-01

    The climate during the past hundreds of thousands of years has been characterized by a rather distinct periodicity of about 100000 yr with brief warming periods (interglacials) lasting approximately 10000-12000 yr. Today, mankind is living in an interglacial period that began about 11 ka ago. In light of the discussion about global warming observed in recent decades, which advocates of an anthropogenic impact associate with emission of greenhouse gases due to combustion of fossil fuel, the question arises concerning the duration of the current interglacial. The data available on climate change and solar radiation on a time scale of the last millions of years are critically analyzed in this article and the problem of the length of the current interglacial is discussed.

  1. 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…

  2. 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…

  3. 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.

  4. An axisymmetric boundary integral model for incompressible linear viscoelasticity: application to the micropipette aspiration contact problem.

    PubMed

    Haider, M A; Guilak, F

    2000-06-01

    The micropipette aspiration test has been used extensively in recent years as a means of quantifying cellular mechanics and molecular interactions at the microscopic scale. However, previous studies have generally modeled the cell as an infinite half-space in order to develop an analytical solution for a viscoelastic solid cell. In this study, an axisymmetric boundary integral formulation of the governing equations of incompressible linear viscoelasticity is presented and used to simulate the micropipette aspiration contact problem. The cell is idealized as a homogeneous and isotropic continuum with constitutive equation given by three-parameter (E, tau 1, tau 2) standard linear viscoelasticity. The formulation is used to develop a computational model via a "correspondence principle" in which the solution is written as the sum of a homogeneous (elastic) part and a nonhomogeneous part, which depends only on past values of the solution. Via a time-marching scheme, the solution of the viscoelastic problem is obtained by employing an elastic boundary element method with modified boundary conditions. The accuracy and convergence of the time-marching scheme are verified using an analytical solution. An incremental reformulation of the scheme is presented to facilitate the simulation of micropipette aspiration, a nonlinear contact problem. In contrast to the halfspace model (Sato et al., 1990), this computational model accounts for nonlinearities in the cell response that result from a consideration of geometric factors including the finite cell dimension (radius R), curvature of the cell boundary, evolution of the cell-micropipette contact region, and curvature of the edges of the micropipette (inner radius a, edge curvature radius epsilon). Using 60 quadratic boundary elements, a micropipette aspiration creep test with ramp time t* = 0.1 s and ramp pressure p*/E = 0.8 is simulated for the cases a/R = 0.3, 0.4, 0.5 using mean parameter values for primary chondrocytes

  5. Neural prosthetic systems: current problems and future directions.

    PubMed

    Chestek, Cindy A; Cunningham, John P; Gilja, Vikash; Nuyujukian, Paul; Ryu, Stephen I; Shenoy, Krishna V

    2009-01-01

    By decoding neural activity into useful behavioral commands, neural prosthetic systems seek to improve the lives of severely disabled human patients. Motor decoding algorithms, which map neural spiking data to control parameters of a device such as a prosthetic arm, have received particular attention in the literature. Here, we highlight several outstanding problems that exist in most current approaches to decode algorithm design. These include two problems that we argue will unlikely result in further dramatic increases in performance, specifically spike sorting and spiking models. We also discuss three issues that have been less examined in the literature, and we argue that addressing these issues may result in dramatic future increases in performance. These include: non-stationarity of recorded waveforms, limitations of a linear mappings between neural activity and movement kinematics, and the low signal to noise ratio of the neural data. We demonstrate these problems with data from 39 experimental sessions with a non-human primate performing reaches and with recent literature. In all, this study suggests that research in cortically-controlled prosthetic systems may require reprioritization to achieve performance that is acceptable for a clinically viable human system.

  6. The possible role of contact current in cancer risk associated with residential magnetic fields.

    PubMed

    Kavet, R; Zaffanella, L E; Daigle, J P; Ebi, K L

    2000-10-01

    Residential electrical wiring safety practices in the US result in the possibility of a small voltage (up to a few tenths of a volt) on appliance surfaces with respect to water pipes or other grounded surfaces. This "open circuit voltage" (V(OC)) will cause "contact current" to flow in a person who touches the appliance and completes an electrical circuit to ground. This paper presents data suggesting that contact current due to V(OC) is an exposure that may explain the reported associations of residential magnetic fields with childhood leukemia. Our analysis is based on a computer model of a 40 house (single-unit, detached dwelling) neighborhood with electrical service that is representative of US grounding practices. The analysis was motivated by recent research suggesting that the physical location of power lines in the backyard, in contrast to the street, may be relevant to a relationship of power lines with childhood leukemia. In the model, the highest magnetic field levels and V(OC)s were both associated with backyard lines, and the highest V(OC)s were also associated with long ground paths in the residence. Across the entire neighborhood, magnetic field exposure was highly correlated with V(OC) (r = 0.93). Dosimetric modeling indicates that, compared to a very high residential level of a uniform horizontal magnetic field (10 mu T) or a vertical electric field (100 V/m), a modest level of contact current (approximately 18 mu A) leads to considerably greater induced electric fields (> 1 mV/m) averaged across tissue, such as bone marrow and heart. The correlation of V(OC) with magnetic fields in the model, combined with the dose estimates, lead us to conclude that V(OC) is a potentially important exposure with respect to childhood leukemia risks associated with residential magnetic fields. These findings, nonetheless, may not apply to residential service used in several European countries or to the Scandinavian studies concerned with populations exposed to

  7. Flow of the current along metallic shunts in ohmic contacts to wide-gap III-V semiconductors

    SciTech Connect

    Blank, T. V. Goldberg, Yu. A.; Posse, E. A.

    2009-09-15

    It is established experimentally that the contact metal-wide-gap semiconductor (GaAs, GaP, GaN) with the Schottky barrier transforms into the ohmic contact either in the process of continuous heating or in the process of holding at an elevated temperature before the formation of any recrystallized layers. In this case, resistance of the contact reduced to the unit area increases as the temperature increases for semiconductors with a high dislocation density (GaP, GaN). It is assumed that in such contacts, the current flows along the metallic shunts, which shorten the layer of space charge and are formed by metal atoms diffused along the dislocation lines or other imperfections of the semiconductor. In semiconductors with a low dislocation density (GaAs), resistance of the ohmic contact per unit area decreases with increasing the temperature as it was expected for the thermionic mechanism of current flowing.

  8. Three-dimensional fundamental thermo-elastic solutions applied to contact problems

    NASA Astrophysics Data System (ADS)

    Wang, Z. P.; Wang, T.; Li, P. D.; Li, X. Y.; Chen, W. Q.; Müller, R.

    2016-11-01

    This paper aims to develop three-dimensional fundamental thermo-elastic solutions for an infinite/half-infinite space of a two-dimensional hexagonal quasi-crystal, which is subjected to a point heat source. Starting from the newly developed general solution in terms of quasi-harmonic potential functions, the corresponding fundamental solutions are derived by means of the trial-and-error technique. Six appropriate potential functions involved in the general solution are observed. The present fundamental solutions are applied to construct boundary integral equations governing the contact problems. Numerical calculations are performed to show the distributions of the thermo-elastic coupling field variables in a half-space subjected to a point thermal source.

  9. 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,…

  10. Adaptive multi-analysis strategy for contact problems with friction. Application to aerospace bolted joints

    NASA Astrophysics Data System (ADS)

    Champaney, L.; Boucard, P.-A.; Guinard, S.

    2008-07-01

    The objective of the work presented here is to develop an efficient strategy for the parametric analysis of bolted joints designed for aerospace applications. These joints are used in elastic structural assemblies with local nonlinearities (such as unilateral contact with friction) under quasi-static loading. Our approach is based on a decomposition of an assembly into substructures (representing the parts) and interfaces (representing the connections). The problem within each substructure is solved by the finite element method, while an iterative scheme based on the LATIN method (Ladevèze in Nonlinear computational structural mechanics—new approaches and non-incremental methods of calculation, 1999) is used for the global resolution. The proposed strategy consists in calculating response surfaces (Rajashekhar and Ellingwood in Struct Saf 12:205-220, 1993) such that each point of a surface is associated with a design configuration. Each design configuration corresponds to a set of values of all the variable parameters (friction coefficients, prestresses) which are introduced into the mechanical analysis. Here, instead of carrying out a full calculation for each point of the surface, we propose to use the capabilities of the LATIN method and reutilize the solution of one problem (for one set of parameters) in order to solve similar problems (for the other sets of parameters) (Boucard and Champaney in Int J Numer Methods Eng 57:1259-1281, 2003). The strategy is adaptive in the sense that it takes into account the results of the previous calculations. The method presented can be used for several types of nonlinear problems requiring multiple analyses: for example, it has already been used for structural identification (Allix and Vidal in Comput Methods Appl Mech Eng 191:2727-2758, 2001).

  11. 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).

  12. 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. 2011 Elsevier Inc. All rights reserved.

  13. 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.

  14. Power Counting of Contact-Range Currents in Effective Field Theory

    NASA Astrophysics Data System (ADS)

    Valderrama, M. Pavón; Phillips, D. R.

    2015-02-01

    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 1S0 N N 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.

  15. Dependence of current switching dynamics on contact conductivity in semiconductor superlattices

    NASA Astrophysics Data System (ADS)

    Teitsworth, Stephen W.; Xu, Huidong

    2006-03-01

    Numerical simulation results are presented for a discrete drift-diffusion electronic transport model appropriate to weakly-coupled semiconductor superlattices [1]. Sequential resonant tunneling between adjacent quantum wells is the primary conduction mechanism for this model which also incorporates an effective contact conductivity σc. We study the dependence on σc of time-averaged current-voltage characteristics and transient current response to abrupt steps in applied voltage. For intermediate values of σc, three qualitatively distinct transient responses -- each associated with a different mechanism for the relocation of a static charge accumulation layer [1] - are observed for different values of voltage step Vstep; these involve, respectively, 1) the motion of a single charge accumulation layer, 2) the simultaneous motion of one depletion and two accumulation layers [2], and 3) the simultaneous motion of two accumulation layers. The range of Vstep values for each mechanism and the relocation times associated with each are studied as a function of σc; a critical value of σc is identified above which the second relocation mechanism is not observed for any value of Vstep. Relocation times are found to depend sensitively on specific values of σc and Vstep. [1] L. L. Bonilla and H. T. Grahn, Rep. Prog. Phys. 68, pp. 577-683 (2005), and refs. therein. [2] A. Amann, A. Wacker, L. L. Bonilla, and E. Schoell, Phys. Rev. E 63, 066207 (2001).

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

    SciTech Connect

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

    2016-08-07

    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{sup −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.

  17. Current flow in a 3-terminal thin film contact with dissimilar materials and general geometric aspect ratios

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Hung, Derek M. H.; Lau, Y. Y.

    2013-02-01

    The current flow pattern, together with the contact resistance, is calculated analytically in a Cartesian 3-terminal thin film contact with dissimilar materials. The resistivities and the geometric dimensions in the individual contact members, as well as the terminal voltages, may assume arbitrary values. We show that the current flow patterns and the contact resistance may be conveniently decomposed into the even and odd solution. The even solution gives exclusively and totally the current flowing from the source to the gate. The odd solution gives exclusively and totally the current flowing from the source to the drain. Current crowding at the edges, and current partition in different regions are displayed. The analytic solutions are validated using a simulation code. The bounds on the variation of the contact resistance are given. This paper may be considered as the generalization of the transmission line model and the Kennedy-Murley model that were used extensively in the characterization of thin-film devices. For completeness, we include the general results for the cylindrical geometry, which are qualitatively similar to the even solution of the Cartesian geometry.

  18. Current Health-Related Quality of Life in Former National Collegiate Athletic Association Division I Collision Athletes Compared With Contact and Limited-Contact Athletes

    PubMed Central

    Simon, Janet E.; Docherty, Carrie L.

    2016-01-01

    Context:  Previous researchers have shown that current health-related quality of life (HRQoL) is lower in former National Collegiate Athletic Association Division I athletes than in nonathletes. However, evidence supports the idea that individuals in collision sports (football) may suffer more serious injuries that may affect them later in life. Objective:  To measure HRQoL in former Division I collision, contact, and limited-contact athletes. Design:  Cross-sectional study. Setting:  Research laboratory. Patients or Other Participants:  A total of 374 former Division I athletes between the ages of 40 and 65 years were separated into collision, contact, and limited-contact groups. Intervention(s):  All individuals completed the Short Form 36 version 2 via a computer. Main Outcome Measures(s):  The dependent variables were the physical component and mental component summary scores and the physical functioning, physical role functioning, bodily pain, general health, vitality, social role functioning, emotional role functioning, and mental health scales. An initial multivariate analysis of covariance included data from the 2 domains: physical component and mental component summary scores. The second multivariate analysis of covariance included data from the 8 dimensions: physical function, role physical, bodily pain scale, general health, mental health, role emotional, social function, and vitality scales. The α level was set at P < .05 with a covariate of sex. Results:  The responses were significantly lower (worse) for the former collision athletes compared with the contact and limited-contact athletes for the summary scores (F2,370 = 90.09, P < .01) and all 8 scales (F8,364 = 24.33, P < .01). The largest differences were between the collision and limited-contact athletes for the bodily pain and role physical scales, with mean differences of 12.91 and 11.80 points, respectively. Conclusions:  Competing at the Division I level can be strenuous on

  19. Surface layer structure and average contact temperature of copper-containing materials under dry sliding with high electric current density

    NASA Astrophysics Data System (ADS)

    Fadin, V. V.; Aleutdinova, M. I.; Rubtsov, V. Ye.; Aleutdinov, K. A.

    2016-11-01

    Dry sliding of copper and powder composites of Cu-Fe and Cu-Fe-graphite compositions against 1045 steel under electric current of contact density higher than 250 A/cm2 has been studied, which demonstrated the change in surface layer structure and formation of tribolayer consisting of iron, copper and FeO oxide. Signs of quasi-viscous flow of worn surface were observed. It was noted that the thin contact layer containing about 40 at % of oxygen and 40% of Fe was the main factor decreasing the adhesion interaction. It was affirmed that the introduction of graphite into the primary structure of the composite leads to rather low content of FeO oxide and to the increased tendency of surface layer to catastrophic deterioration under sliding with contact current density of about 300 A/cm2. The temperature of contact did not exceed 400°C.

  20. The effect of contact barriers on space-charge-limited current injection in impurity-band-conduction photodetectors

    NASA Astrophysics Data System (ADS)

    Martin, B. G.

    1994-05-01

    A theoretical investigation was made on the effect of contact barriers on space-charge-limited (SCL) current injection in impurity-band-conduction (IBC) photodetectors. Parmenter and Ruppel [J. Appl. Phys. 30, 1548 (1959)] considered the effect of contact barriers on SCL current injection in insulators. They solved the steady-state, one-dimensional transport equations, obtaining the solution in terms of integrals, which they evaluated for certain limiting cases. We have modified their approach by using the current injection ratios at the contacts as boundary conditions. This is a very general formulation that can be used for any type of contact barrier. We then applied this technique to model contact barriers in IBC devices. The fact that the IBC hopping mobility is several orders of magnitude smaller than the electron mobility enables us to evaluate the integrals and obtain a closed form solution to the transport equations. Calculated results include current versus voltage behavior, electrostatic potential and electric field versus position for a given bias. It is concluded that the injected electron current is dominant for the store-mode applied bias.

  1. Bifocal contact lenses: History, types, characteristics, and actual state and problems

    PubMed Central

    Toshida, Hiroshi; Takahashi, Kozo; Sado, Kazushige; Kanai, Atsushi; Murakami, Akira

    2008-01-01

    Since people who wear contact lenses (CL) often continue using CL even when they develop presbyopia, there are growing expectations for bifocal CL. To understand actual state and problems, history, types, and their characteristics are summarized in this review. Bifocal CL have a long history over 70 years. Recently, bifocal CL have achieved remarkable progress. However, there still is an impression that prescription of bifocal CL is not easy. It should also be remembered that bifocal CL have limits, including limited addition for near vision, as well as the effects of aging and eye diseases in the aged, such as dry eye, astigmatism, cataract, etc. Analysis of the long-term users of bifocal CL among our patients has revealed the disappearance of bifocal CL that achieved unsatisfactory vision and poor contrast compared with those provided by other types of CL. Changing the prescription up to 3 times for lenses of the same brand may be appropriate. Lenses that provide poor contrast sensitivity, suffer from glare, or give unsatisfactory vision have been weeded out. The repeated replacement of products due to the emergence of improved or new products will be guessed. PMID:19668441

  2. 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.

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

    SciTech Connect

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

    2016-05-28

    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.

  4. The adapted augmented Lagrangian method: a new method for the resolution of the mechanical frictional contact problem

    NASA Astrophysics Data System (ADS)

    Bussetta, Philippe; Marceau, Daniel; Ponthot, Jean-Philippe

    2012-02-01

    The aim of this work is to propose a new numerical method for solving the mechanical frictional contact problem in the general case of multi-bodies in a three dimensional space. This method is called adapted augmented Lagrangian method (AALM) and can be used in a multi-physical context (like thermo-electro-mechanical fields problems). This paper presents this new method and its advantages over other classical methods such as penalty method (PM), adapted penalty method (APM) and, augmented Lagrangian method (ALM). In addition, the efficiency and the reliability of the AALM are proved with some academic problems and an industrial thermo-electromechanical problem.

  5. 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

  6. 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

  7. [Drugs, a current problem: difficulties in handling drug addictions].

    PubMed

    Amigo Tadín, Montserrat

    2005-12-01

    A patient suffering a drug addiction usually presents some characteristic demands and necessities. A professional's attitude must be clear and firm, showing empathy and being an active listener offering assistance, but not expressing either rebuke or threats. The professional attending such a patient takes advantage of a consultation to motivate the patient to begin, or continue, treatment in a corresponding specialized center and will process the necessary paperwork to contact such a center.

  8. 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…

  9. 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…

  10. Contact dermatitis is an unrecognized problem in the construction industry: Comparison of four different assessment methods.

    PubMed

    Timmerman, Johan G; Heederik, Dick; Spee, Ton; van Rooy, Frits G; Krop, Esmeralda J M; Rustemeyer, Thomas; Smit, Lidwien A M

    2017-10-01

    A high contact dermatitis symptoms prevalence has been observed in Dutch construction workers. Contact dermatitis was diagnosed by an expert panel using questionnaire data and photographs of 751 subjects' hands. A subset was evaluated by two occupational physicians. Their diagnoses were compared to those of the expert panel. In addition, two self-reported questionnaire-based assessment methods were compared to the expert panel evaluation. Associations between contact dermatitis and determinants were assessed using log-binomial regression analysis. Contact dermatitis prevalence was high: 61.4% (expert panel's diagnosis) and 32.9% (self-reported). Agreement between occupational physicians and the expert panel was low but increased after training. Washing hands with solvents and performing job-related tasks at home were related to contact dermatitis. Contact dermatitis prevalence among construction workers is high. Recognition of contact dermatitis by occupational physicians is poor but can be improved by training. Awareness of skin disorders should be raised. © 2017 Wiley Periodicals, Inc.

  11. 31 CFR 380.5 - Where can I find current information, and who can I contact for additional guidance and...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Where can I find current information, and who can I contact for additional guidance and interpretation? 380.5 Section 380.5 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FISCAL SERVICE, DEPARTMENT OF THE...

  12. 31 CFR 380.5 - Where can I find current information, and who can I contact for additional guidance and...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 2 2011-07-01 2011-07-01 false Where can I find current information, and who can I contact for additional guidance and interpretation? 380.5 Section 380.5 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FISCAL SERVICE, DEPARTMENT OF THE...

  13. Mixed Ability Science Teaching: Some Current Practices and Problems.

    ERIC Educational Resources Information Center

    Sands, M. K.

    1979-01-01

    Presented is a study of the methods which 21 science teachers were using in mixed ability classes of some secondary schools in the United Kingdom, and their opinions of the benefits and problems of mixed ability teaching. (HM)

  14. Au nanoparticles embedded at the interface of Al/4H-SiC Schottky contacts for current density enhancement

    NASA Astrophysics Data System (ADS)

    Gorji, Mohammad Saleh; Cheong, Kuan Yew

    2015-01-01

    Nanostructured contacts, comprised of nanoparticles (NPs) embedded at the interface of contact/semiconductor, offer a viable solution in modification of Schottky barrier height (SBH) in Schottky contacts. The successful performance of devices with such nanostructured contacts requires a feasible selection of NPs/contact material based on theoretical calculations and a cost effective and reproducible route for NPs deposition. Acidification of commercially available colloidal Au NPs solution by HF has been selected here as a simple bench-top technique for deposition of Au NPs on n- and p-type 4H-SiC substrates. Theoretical calculations based on the model of inhomogeneity in SBH (ISBH) were used to make a more appropriate selection of NPs type (Au) and size (5 and 10 nm, diameter) with respect to contact metal (Al). Al/Au NPs/SiC Schottky barrier diodes were then fabricated, and their electrical characteristics exhibited current density enhancement due to the SBH lowering. The source of SBH lowering was determined to be the local electric field enhancement due to NPs effect, which was further investigated using the models of ISBH and tunneling enhancement at triple interface.

  15. [Substance abuse and the emergency department: a current problem].

    PubMed

    Amigó Tadín, Montserrat

    2005-09-01

    Alcohol, tobacco, heroin, cocaine and benzodiazepines, in that order, are the most common substance addictions in Spain. The medical problems caused both by chronic medical pathologies associated with their consumption and by overdoses and withdrawal syndromes, are frequently seen in emergency departments. Knowledge of substance abuse and addiction--how it is caused, the behaviour and pathology it produces--are essential to enable nurses to determine the attitudes to adopt the skills necessary to manage patients with problems of substance.

  16. 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.

  17. Contact Problems for Elasto-Plastic Impact in Multi-Body Systems

    NASA Astrophysics Data System (ADS)

    Stronge, W. J.

    Low to moderate speed collision between elastic-plastic bodies results in imperceptible permanent indentation of the contact surfaces if the bodies are hard. Nevertheless in these collisions the contact force-indentation relation is irreversible since internal energy gained from work done by the contact force during the compression is partially trapped in elastic waves, work done in plastic deformation and work done to overcome friction during sliding. These sources of kinetic energy l oss in collisions depend on relative velocity between the bodies at the contact point, material properties, inertia properties related to the impact configuration and geometric constraints on the deformation field. Colliding bodies that can be represented as elastic-plastic or visco-plastic solids have been analyzed using specific models of contact compliance to calculate the energy transformed into irrecoverable forms. These calculations show how elastic waves, plastic deformation and friction affect the energetic coefficient of restitution - a coefficient that is a measure of impact energy loss from internal sources. The calculations indicate that there is considerable difference in the sources of energy loss f or 2D and 3D deformations. Also, that friction little affects the plastic energy losses unless the impact speed is large enough to cause uncontained plastic deformation beneath the contact area. Consequently, for low-speed impact rhonu_3^2 (0) / Y , the energetic coefficient of friction e* is insensitive to friction. In analysing impact of multi-body systems (e.g. mechanisms, kinematic chains or agglomerates of granules), it is crucial to employ these ideas by specifically modelling the contact compliance. During impact on a mechanism, the velocity changes in one area of contact induce small displacements that develop at other compliant contacts where the impacted body is supported or connected to other elements; the force that develops at these secondary contacts (as a

  18. 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.

  19. 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…

  20. 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...

  1. 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...

  2. Obtaining macroscopic quantities for the contact line problem from Density Functional Theory using asymptotic methods

    NASA Astrophysics Data System (ADS)

    Sibley, David; Nold, Andreas; Kalliadasis, Serafim

    2015-11-01

    Density Functional Theory (DFT), a statistical mechanics of fluids approach, captures microscopic details of the fluid density structure in the vicinity of contact lines, as seen in computations in our recent study. Contact lines describe the location where interfaces between two fluids meet solid substrates, and have stimulated a wealth of research due to both their ubiquity in nature and technological applications and also due to their rich multiscale behaviour. Whilst progress can be made computationally to capture the microscopic to mesoscopic structure from DFT, complete analytical results to fully bridge to the macroscale are lacking. In this work, we describe our efforts to bring asymptotic methods to DFT to obtain results for contact angles and other macroscopic quantities in various parameter regimes. We acknowledge financial support from European Research Council via Advanced Grant No. 247031.

  3. Current problems of mathematical physics and computational mathematics

    NASA Astrophysics Data System (ADS)

    Tikhonov, A. N.

    This collection, designed to honor the work of Academician A. A. Samarskii on his 60th birthday, treats such subjects as theoretical and mathematical physics, the general theory of numerical methods and algorithms, and the numerical study of applied problems of mechanics and plasma physics. Particular attention is given to the acceleration of charged particles by laser radiation, numerical methods for solving problems of MHD equilibrium, the use of the small-parameter method to solve differential equations, mathematical models of the initial stage of tokamak discharges, and radiative energy losses during the ultrahigh compression of laser fusion targets. Also considered are mixed strategies in differential games, methods for the numerical modeling of turbulent flows of viscous incompressible fluids, mathematical modeling of systems for the formation and focusing of charged-particle beams, and the use of variational principles in numerical modeling.

  4. Current problems and potential techniques in in vivo glucose monitoring.

    PubMed

    Wickramasinghe, Y; Yang, Y; Spencer, S A

    2004-09-01

    Accurate in vivo monitoring of glucose concentration would be a valuable asset, particularly for management of diabetes and preterm infants during critical care. In vivo glucose monitoring devices can be divided into two categories: implanted and non-invasive. Extensive research into in vivo glucose monitoring over recent decades has not resulted in the widespread use of clinically reliable monitoring systems. For implanted devices, poor biocompatibility of the materials used for fabrication remains a major challenge, whilst progress in the commercial development of non-invasive devices is hampered by the problem of multiple interference between the detected signals and the biological components. In this review, the methods available for in in-vivo glucose monitoring are described and the associated problems are discussed.

  5. The role of contact system in septic shock: the next target? An overview of the current evidence.

    PubMed

    Nicola, Henrique

    2017-01-01

    Septic shock remains challenging to intensive care units worldwide, despite recent documented improvement in mortality over the years. Multiple new therapies have been attempted without success in large clinical trials. Evidence concerning the role of the contact system and bradykinin on septic shock physiological manifestations is shown by this article. The objective of the study is to review the current evidence linking contact system activation and septic shock, as well as efficacy of available therapies targeting this pathophysiological pathway and to evaluate the potential of further researching the matter. Multiple animal studies are already available and suggestive of a meaningful role of contact system activation on septic shock. However, human trials are still scarce, and the ones available are not enough to establish such a strong connection. Furthermore, attempted therapies have been successful across multiple species, but not as much in humans. Therefore, contact system and septic shock relationship remains plentiful in questions to be answered in the coming years or decades. Whether the contact system is not as relevant in humans as it is in animals or there is only lack of evidence remains to be explained. The subject is an attractive open field for further research aiming to aid in tackling such a burdensome condition.

  6. Eddy-current NDE inverse problem with sparse grid algorithm

    NASA Astrophysics Data System (ADS)

    Zhou, Liming; Sabbagh, Harold A.; Sabbagh, Elias H.; Murphy, R. Kim; Bernacchi, William; Aldrin, John C.; Forsyth, David; Lindgren, Eric

    2016-02-01

    In model-based inverse problems, the unknown parameters (such as length, width, depth) need to be estimated. When the unknown parameters are few, the conventional mathematical methods are suitable. But the increasing number of unknown parameters will make the computation become heavy. To reduce the burden of computation, the sparse grid algorithm was used in our work. As a result, we obtain a powerful interpolation method that requires significantly fewer support nodes than conventional interpolation on a full grid.

  7. 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.

  8. 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.

  9. 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.

  10. Brief research on arch hinge of the steel truss arch bridge by contact problem under local stress

    NASA Astrophysics Data System (ADS)

    He, Wei; Zhu, Yinqiao; Chen, Renlong

    2017-06-01

    Because of its wide deck, elegant design and reasonable stress, the steel truss arch bridge is suitable for urban bridges. In the steel truss arch bridge, the main arch hinge is an important structure, the local structure and the stress is complex, and it is necessary to analyze the local stress state of the arch hinge. Arch hinge problem belongs to the contact problem, this paper based on Chengdu Tianfu District Shenyang Lu Xi Duan Jin Jiang in bearing steel truss arch bridge design, take the finite element software ANSYS on the main arch hinge is locally analyzed, the arch at the junction of reliable performance test. Studies have shown that half through steel truss arch bridge should be adopted by reasonable cylindrical arch hinge, and Hertz theory is in the analysis of the arch hinge contact does not apply.

  11. A numerical analysis of contact and limit-point behavior in a class of problems of finite elastic deformation

    NASA Technical Reports Server (NTRS)

    Endo, T.; Oden, J. T.; Becker, E. B.; Miller, T.

    1984-01-01

    Finite element methods for the analysis of bifurcations, limit-point behavior, and unilateral frictionless contact of elastic bodies undergoing finite deformation are presented. Particular attention is given to the development and application of Riks-type algorithms for the analysis of limit points and exterior penalty methods for handling the unilateral constraints. Applications focus on the problem of finite axisymmetric deformations, snap-through, and inflation of thick rubber spherical shells.

  12. On the distinguished limits of the Navier slip model of the moving contact line problem

    NASA Astrophysics Data System (ADS)

    Ren, Weiqing; Trinh, Philippe H.; E, Weinan

    2015-06-01

    When a droplet spreads on a solid substrate, it is unclear what are the correct boundary conditions to impose at the moving contact line. The classical no-slip condition is generally acknowledged to lead to a non-integrable singularity at the moving contact line, for which a slip condition, associated with a small slip parameter, $\\lambda$, serves to alleviate. In this paper, we discuss what occurs as the slip parameter, $\\lambda$, tends to zero. In particular, we explain how the zero-slip limit should be discussed in consideration of two distinguished:: one where time is held constant $t = O(1)$, and one where time tends to infinity at the rate $t = O(|\\log \\lambda|)$. The crucial result is that in the case where time is held constant, the $\\lambda \\to 0$ limit converges to the slip-free equation, and contact line slippage occurs as a regular perturbative effect. However, if $\\lambda \\to 0$ and $t \\to \\infty$, then contact line slippage is a leading-order singular effect.

  13. Current Trends in Canine Problem-Solving and Cognition

    PubMed Central

    Miklósi, Ádám; Kubinyi, Enikő

    2017-01-01

    Dogs have occupied a central place in modern comparative cognition, partly because of their specific past and present relationship with humans. Over the years, we have gained insights about the functioning of the dog’s mind, which has helped us to understand how dogs’ problem-solving abilities differ from those present in related species such as the wolf. Novel methodologies are also emerging that allow for the study of neural and genetic mechanisms that control mental functions. By providing an overview from an ethological perspective, we call for greater integration of the field and a better understanding of natural dog behavior as a way to generate scientific hypotheses. PMID:28503035

  14. [Current aspects of the noise problem in aviation medicine].

    PubMed

    Vorob'ev, O A; Krylov, Iu V; Zaritskiĭ, V V; Skrebnev, S V

    1996-02-01

    The authors discuss the problem of improvement the noise factor prevention in aviation medicine. The analysis of the real acoustic load on aviation engineer specialists, performing maintenance of the modern military aircraft have been given. The authors show the importance of the approach to the aviation noise as an ecological significant factor, that means taking into account the acoustic load during work time as well as during rest-sleep periods. The authors suggested the advanced complex of the preventive measures for the purpose of optimization of the noise exposure on the aviation specialists.

  15. [Current problems in the treatment of open fractures].

    PubMed

    Weller, S

    1975-01-01

    The paper evidently does not discuss several important problems of the management of open fractures, but it is confined to the exposition of some fundamental rules of their traitment. Nowadays, the treatment of open fractures is to be decided individually for all cases. A great number of patients with open fracture owe their recovery to the proper first aid care at scence of accident. This is also in respect of the further treatment in the hospital of great importance. Exagerated activity is usually superfluous in the treatment of open fractures. Less and more proper management is often more useful for the injured patient.

  16. [Proteomics in Chinese medicine researches: current status, problems and strategies].

    PubMed

    Xiong, Shao-quan; Zhou, Dai-han; Long, Qi-da

    2010-02-01

    Proteomics plays important roles in Chinese medicine research at post-genomics era. Its research idea and methods are beneficial for elucidating some elemental features of Chinese medicine. At present, Chinese medicine proteomic studies are mainly focusing on the syndromatology and medical herbal pharmacology. However, there are still some problems, the most important matter was that most of the results were merely the superficial delineations. Further research should put emphasize on the unremitting and penetrating study of proteomics, molecular biology and bioinformatics integrally for illuminating Chinese medicine theory deeply to promote the modernization of Chinese medicine research.

  17. [Current problems of occupational morbidity on the railway transport].

    PubMed

    Pankova, V B; Kameneva, E A; Artemenkov, Iu M; Glebova, G M

    2006-01-01

    The paper discusses the present working conditions on railway transport, by using the results of employee rating, characterizes railway services showing the greatest magnitude of adverse and dangerous factors of working conditions. It also characterizes occupational morbidity in railway transport workers over 5 years (1999-2003) and by hazards problems of occupational morbidity and by basic services: locomotive, wagon, and track ones. The paper also presents the rates of disability due to occupational diseases, characterizes the priorities of prevention of occupational diseases on the railway transport.

  18. [Current status of lung transplantation in China: problems and perspectives].

    PubMed

    Wang, X A; Jiang, G N

    2016-12-01

    Despite rapid progress, clinical lung transplantation in China still lags far behind. A great challenge remains in donor lung utilization and perioperative medicine. It's really abnormal that we are so backward in lung transplantation when we have come up with the advanced world levels in thoracic surgery, pulmonology and critical care medicine. Our shortcomings were analyzed by comparing lung transplantation in China and in the advanced countries. The first problem is multidisciplinary teamwork. In the United States, a lung transplant team includes physician specialized in lung transplantation, thoracic surgeons, nurses, respiratory therapists and other specialists possibly needed. In contrast, our lung transplant teams are derived from thoracic surgery teams. Other specialists are invited for consultation just when thoracic surgeons are unable to deal with the tough issues in perioperative medicine. The low utilization and quality of donor lung also result from poor teamwork. The second problem is that we failed to integrate such advances as extra corporeal lung support and ex vivo lung perfusion into our lung transplant programs. In conclusion, the development of lung transplantation in China is dependent upon an initiative, multidisciplinary team approach.

  19. Drain current drift by holes trapped in Schottky contact in WSi gate GaAs MESFeTs

    SciTech Connect

    Shiga, T.; Hattori, R.; Kunii, T.

    1995-12-31

    Hysteretic drain current (Id) drift phenomena observed in the high power operation of WSi gate GaAs MESFETs were studied. The existence of a thin insulating layer at WSi/GaAs interface originated by the native oxide on GaAs surface was revealed by XPS and X-ray reflection. Id drift phenomena can be explained as the effect of holes being trapped in the insulating layer at the WSi/GaAs Schottky contact interface.

  20. 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.

  1. 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

  2. Endometrial biopsy interpretation. Shortcomings and problems in current gynecologic practice.

    PubMed

    Van Bogaert, L J; Maldague, P; Staquet, J P

    1978-01-01

    The analysis of 345 endometrial biopsies was carried out with special regard to the relation between pathologic findings and presenting symptoms or complaints. Only 52.4% of the biopsies showed microscopic features possibly related to the complaints. Endometrial polyps and chronic endometritis were diagnosed in 21.1 and 9.8%, respectively, of the entire study group. The currently accepted definitions of dysfunctional uterine bleeding raise the question whether endometrial polyps and atypical secretory changes may or may not be included in the syndrome.

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

    PubMed Central

    Lord, J

    2003-01-01

    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

  4. Problems with the current deinococcal hypothesis: an alternative theory.

    PubMed

    Sghaier, Haïtham; Narumi, Issay; Satoh, Katsuya; Ohba, Hirofumi; Mitomo, Hiroshi

    2007-08-01

    All theories related to the evolution of Deinococcus radiodurans have a common denominator: the strong positive correlation between ionizing-radiation resistance and desiccation tolerance. Currently, the widespread hypothesis is that D. radiodurans' ionizing-radiation resistance is a consequence of this organism's adaptation to desiccation (desiccation adaptation hypothesis). Here, we draw attention to major discrepancy that has emerged between the "desiccation adaptation hypothesis" and recent findings in computational biology, experimental research, and terrestrial subsurface surveys. We explain why the alternative hypothesis, suggesting that D. radiodurans' desiccation tolerance could be a consequence of this organism's adaptation to ionizing radiation (radiation adaptation hypothesis), should be considered on equal basis with the "desiccation adaptation hypothesis".

  5. Current research on the major nematode problems in Japan.

    PubMed

    Ichinohe, M

    1988-04-01

    AMONG IMPORTANT NEMATODE SPECIES OCCURRING IN JAPAN, CURRENT RESEARCH ACHIEVEMENTS WITH THE FOLLOWING FOUR NEMATODES ARE REVIEWED: 1) Soybean cyst nematode (SCN), Heterodera glycines - breeding for resistance, race determination, association with Cephalosporium gregatum in azuki bean disease, and isolation of hatching stimulant. 2) Potato-cyst nematode (PCN), Globodera rostochiensis - pathotype determination (Ro 1), breeding for resistance, and control recommendations. 3) Pinewood nematode (PWN), Bursaphelenchus xylophilus - primary pathogen in pine wilt disease, life cycle exhibiting a typical symbiosis with Japanese pine sawyer, Monochamus alternatus, and project for control. 4) Rice root nematodes (RRN), Hirschmanniella imamuri and H. oryzae - distribution of species, population levels in roots, and role of these nematodes in rice culture.

  6. Channel Current Analysis for Pore-forming Properties of an Antimicrobial Peptide, Magainin 1, Using the Droplet Contact Method.

    PubMed

    Watanabe, Hirokazu; Kawano, Ryuji

    2016-01-01

    This study describes the pore-forming properties of magainin 1 in planar lipid bilayers. These bilayers were prepared by the droplet contact method, which was executed on a microfabricated device for a high-throughput study. We arrayed four droplet chambers parallelly in the single device, and the current measurements were carried out simultaneously. Using this system, we measured the channel current conductance of magainin 1. We determined the pore size and the number of assembling monomers in magainin pores in mammalian and bacterial model membranes. This system is a powerful tool for analyzing transmembrane peptides and their antimicrobial activities.

  7. [The current state of the brain-computer interface problem].

    PubMed

    Shurkhay, V A; Aleksandrova, E V; Potapov, A A; Goryainov, S A

    2015-01-01

    It was only 40 years ago that the first PC appeared. Over this period, rather short in historical terms, we have witnessed the revolutionary changes in lives of individuals and the entire society. Computer technologies are tightly connected with any field, either directly or indirectly. We can currently claim that computers are manifold superior to a human mind in terms of a number of parameters; however, machines lack the key feature: they are incapable of independent thinking (like a human). However, the key to successful development of humankind is collaboration between the brain and the computer rather than competition. Such collaboration when a computer broadens, supplements, or replaces some brain functions is known as the brain-computer interface. Our review focuses on real-life implementation of this collaboration.

  8. 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.

  9. Contact allergy to fragrances: current patch test results (2005-2008) from the Information Network of Departments of Dermatology.

    PubMed

    Uter, Wolfgang; Geier, Johannes; Frosch, Peter; Schnuch, Axel

    2010-11-01

    Contact sensitization to fragrances is common both in clinical and in population samples. The spectrum of allergens is broad and diverse, and to some extent covered by a set of screening agents. To examine the current frequency of contact sensitization to fragrance allergens in patients routinely patch tested for suspected allergic contact dermatitis with the baseline series and special series. Between 2005 and 2008, 40 709 patients were patch tested in the departments of the Information Network of Departments of Dermatology (http://www.ivdk.org). Results with selected fragrances were analysed. Of all patients tested with the German baseline series, 15.1% reacted positively to fragrance mix (FM) I (6.6% positive), FM II (4.6% positive) or Myroxylon pereirae resin (balsam of Peru, 6.8% positive). Among the single constituents of FM I, Evernia prunastri [oak moss absolute (abs.)] was the leading allergen, and amyl cinnamal the least frequent allergen. Among fragrances not included in FM I or FM II, Evernia furfuracea (tree moss abs.) was the most common allergen. For diagnostic purposes, it is necessary to combine several screening agents. The frequency of contact sensitization differs greatly between single fragrances. © 2010 John Wiley & Sons A/S.

  10. 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

  11. 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

  12. 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.

  13. Sleep medicine in Saudi Arabia: Current problems and future challenges.

    PubMed

    Bahammam, Ahmed S

    2011-01-01

    Sleep medicine is a relatively new specialty in the medical community. The practice of sleep medicine in Saudi Arabia (KSA) began in the mid to late nineties. Since its inception, the specialty has grown, and the number of specialists has increased. Nevertheless, sleep medicine is still underdeveloped in the KSA, particularly in the areas of clinical service, education, training and research. Based on available data, it appears that sleep disorders are prevalent among Saudis, and the demand for sleep medicine service is expected to rise significantly in the near future. A number of obstacles have been defined that hinder the progress of the specialty, including a lack of trained technicians, specialists and funding. Awareness about sleep disorders and their serious consequences is low among health care workers, health care authorities, insurance companies and the general public. A major challenge for the future is penetrating the educational system at all levels to demonstrate the high prevalence and serious consequences of sleep disorders. To attain adequate numbers of staff and facilities, the education and training of health care professionals at the level of sleep medicine specialists and sleep technologists is another important challenge that faces the specialty. This review discusses the current position of sleep medicine as a specialty in the KSA and the expected challenges of the future. In addition, it will guide clinicians interested in setting up new sleep medicine services in the KSA or other developing countries through the potential obstacles that may face them in this endeavor.

  14. 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.

  15. Potential theory method for 3D crack and contact problems of multi-field coupled media: a survey.

    PubMed

    Chen, Wei-qiu; Ding, Hao-jiang

    2004-09-01

    This paper presents an overview of the recent progress of potential theory method in the analysis of mixed boundary value problems mainly stemming from three-dimensional crack or contact problems of multi-field coupled media. This method was used to derive a series of exact three dimensional solutions which should be of great theoretical significance because most of them usually cannot be derived by other methods such as the transform method and the trial-and-error method. Further, many solutions are obtained in terms of elementary functions that enable us to treat more complicated problems easily. It is pointed out here that the method is usually only applicable to media characterizing transverse isotropy, from which, however, the results for the isotropic case can be readily obtained.

  16. [Pharmacotherapy of epilepsy--current problems and controversies].

    PubMed

    Schmidt, D

    1983-11-01

    Current trends and controversies in the antiepileptic drug therapy are reviewed from a clinical view. The usefulness of prophylactic therapy of febrile seizures and posttraumatic seizures or posttraumatic epilepsy is compromised by difficulties in the management of the patients especially by noncompliance. Previously untreated epilepsies can be treated successfully in 70--80% of the patients. Phenytoin or carbamazepine are equally effective for generalized tonic-clonic seizures of focal seizures, while absence seizures are controlled by ethosuximide or valproic acid. Only when the epilepsy is uncontrolled despite high plasma concentrations which cannot be raised because of side effects, a second drug should be given. A second drug is successful in about one out of six patients with focal epilepsy. Phenytoin, carbamazepine, phenobarbital and primidone seem to be equally effective for these drug-resistant cases. Status epilepticus can be treated with intravenous diazepam or phenytoin and, if necessary, with an infusion of phenytoin. Rectal diazepam is useful for acute pediatric therapy. Drugs of second choice are clonazepam, phenobarbital, lidocaine, and clomethiazole. In the pregnant epileptic patient a drop in the plasma concentration of antiepileptic drugs mainly through non-compliance and seizure provocation through sleep deprivation are major sources for the deterioration of epilepsies during pregnancy. The "fetal antiepileptic drug syndrome", malformations and an increased risk for epilepsy in the child are discussed as an interaction of parental epilepsy and drug-exposure during pregnancy. Finally, the interpretation of abnormal clinical chemistry data is reviewed. Disorders of the liver, bone, thyroid gland and blood are rarely seen in treated epileptic patients usually when specific risk factors are present. The over-interpretation of laboratory abnormalities e.g. an isolated increase of gamma-GT may lead to iatrogenic deterioration of epilepsy when the

  17. [The maternal phenylketonuria syndrom--still current problem].

    PubMed

    Didycz, Bozena; Domagała, Lucyna; Pietrzyk, Jacek J

    2009-01-01

    syndrome: microcephaly was diagnosed in 17 cases, congenital heart defect and microcephaly in 6 children, and microcephaly and the anal atresia in 1 child. Among the children, born from unplanned pregnancies, there are two (twins), whose mother from the 6 week of gestation had returned to applying diet (average phe levels 6.37 mg/dl); two children of mothers who were conducting the therapeutic implemented since 18-th and 32-th weeks of gestation (average phe 7.5 mg/dl) (there is the lack of detailed data about these children, because the women are never reported to our Outpatient Clinic), and one child, whose mother raised and began the therapy from 12-th week of gestation (average phe levels 10.37 mg/dl), who presents the features of ADHD syndrome. 1. All pregnancies of women with hyperphenylalaninemia should be planned to avoid the complications in the form of maternal PKU syndrom. 2. It is essential to educate the women with PKU and their families about the problems concerning maternal PKU. 3. It is also necessary to inform pediatricians, family physicians and gynaecologists-obstetricians about the features of maternal PKU syndrom.

  18. A "current contact news" follow-up: controversial subjects and those resulting in litigation.

    PubMed

    Fisher, A A

    1993-11-01

    In May 1993, the US Food and Drug Administration (FDA) granted product approval for the first female condom made of polyurethane. It provides some protection against sexually transmitted diseases (STDs), but the data are limited on the effectiveness of the Reality Vaginal Pouch against STDs. Female condom users have a relatively high pregnancy rate. FDA requires the label for Reality to stress that latex condoms for men are most effective against STDs and HIV/AIDS. Men who are sensitive to rubber can use condoms made of sheep intestine or cecum (brand names: Fourex and Lambskin). These nonrubber male condoms prevent pregnancy, but do not prevent HIV transmission. A specialist in contact dermatitis suggests that rubber sensitive men use a nonrubber condom directly over the penis and then cover that condom with a rubber condom to protect against HIV transmission. A nonlatex thermoplastic elastomer has been used to make male condoms since the early 1990s, but FDA has yet to approve it. A recent article suggests that a thermoplastic elastomer may be the only choice for rubber sensitive males. FDA approval will increase the availability of a nonlatex thermoplastic elastomer condom. The contact dermatitis specialist reviews and follows up on other articles he has written over the last 20 years. Topics include ethylene oxide burns in hospitalized patients, paraben paradox, benzocaine as a contaminant in sunscreens containing glyceryl PABA, sensitivity to nickel, misuse of a patch test to detect hypersensitivity to mercury amalgam dental fillings, permanent destruction of the fingernails due to an allergic reaction to an acrylic nail preparation, and dermatitis due to visual display units.

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

    SciTech Connect

    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.

  20. 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

  1. Spin current induced by a charged tip in a quantum point contact

    NASA Astrophysics Data System (ADS)

    Shchamkhalova, B. S.

    2017-03-01

    We show that the charged tip of the probe microscope, which is widely used in studying the electron transport in low-dimensional systems, induces a spin current. The effect is caused by the spin-orbit interaction arising due to an electric field produced by the charged tip. The tip acts as a spin-flip scatterer giving rise to the spin polarization of the net current and the occurrence of a spin density in the system.

  2. Application of the contact transformation method to torsional problems in methyl silane

    NASA Astrophysics Data System (ADS)

    Moazzen-Ahmadi, N.; Ozier, I.

    1987-11-01

    The effect of the torsional degree of freedom on redundancies in the Hamiltonian and on the dipole operator has been investigated for methyl silane-like molecules. By applying a rotational contact transformation to the torsion-rotation Hamiltonian HTR for the ground vibrational state, a systematic method is demonstrated for treating the redundancies that relate different terms in HTR. In general, with this method, the experimentally accessible molecular parameters in the reduced Hamiltonian can be related to the physically significant molecular parameters in the untransformed Hamiltonian. It is shown that HTR contains a new term which has matrix elements with selection rules (Δ K = ±3), (Δ σ = 0), and Δ vT arbitrary, where vT and σ label the torsional levels and sublevels, respectively. As a result of this term, the distortion dipole constant μD which characterizes (Δ K = ±3) matrix elements in C3 v molecules cannot, in systems like CH 3SiH 3, be ascribed entirely to centrifugal distortion but can contain a significant contribution from torsional effects. Furthermore, new transitions can appear in the pure torsional bands which may be strong enough to observe in low barrier molecules. By applying a vibrational contact transformation, the form is derived of the leading torsional terms in the dipole moment expansion. The four dipole distortion constants μ0T, μ2T, μ|;T, and μΛT which characterize these terms are related to the molecular parameters that enter the Coriolis, centrifugal distortion, and anharmonicity contributions to the vibration-torsion-rotation Hamiltonian.

  3. Views of Teachers Working in South-East Anatolia Region Regarding Current Problems in Education

    ERIC Educational Resources Information Center

    Bagceci, Birsen

    2017-01-01

    The purpose of this study is to identify the current problems of the teachers working in the provinces of Southeastern Anatolia in Turkey and to list these problems according to their importance. Screening model is used in the study. One open-ended question was asked (identify seven problems related to the education system and order them according…

  4. 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…

  5. 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…

  6. Quantum Monte Carlo study of the Bose-polaron problem in a one-dimensional gas with contact interactions

    NASA Astrophysics Data System (ADS)

    Parisi, L.; Giorgini, S.

    2017-02-01

    We present a theoretical study based upon quantum Monte Carlo methods of the Bose polaron in one-dimensional systems with contact interactions. In this instance of the problem of a single impurity immersed in a quantum bath, the medium is a Lieb-Liniger gas of bosons ranging from the weakly interacting to the Tonks-Girardeau regime, whereas the impurity is coupled to the bath via a different contact potential, producing both repulsive and attractive interactions. Both the case of a mobile impurity, having the same mass as the particles in the medium, and the case of a static impurity with infinite mass are considered. We make use of numerical techniques that allow us to calculate the ground-state energy of the impurity, its effective mass, and the contact parameter between the impurity and the bath. These quantities are investigated as a function of the strength of interactions between the impurity and the bath and within the bath. In particular, we find that the effective mass rapidly increases to very large values when the impurity gets strongly coupled to an otherwise weakly repulsive bath. This heavy impurity hardly moves within the medium, thereby realizing the "self-localization" regime of the Landau-Pekar polaron. Furthermore, we compare our results with predictions of perturbation theory valid for weak interactions and with exact solutions available when the bosons in the medium behave as impenetrable particles.

  7. Current applications and efficacy of scleral contact lenses — a retrospective study

    PubMed Central

    Severinsky, Boris; Millodot, Michel

    2010-01-01

    Purpose To evaluate the indications and efficacy of high gas permeable scleral contact lenses (GP-SCL). Methods A total database of 97 consecutive patients (140 eyes) fitted with GP-SCL between January 2003 and December 2008, was retrospectively analyzed to determine the benefits of fitting scleral lenses. All lenses were fitted by preformed technique and were non-fenestrated. Patients included keratoconus – 88 eyes (63 %); corneal irregularities after penetrating keratoplasty – 39 eyes (28 %); various ocular surface disorders: Stevens-Johnson syndrome (SJS), graft versus host disease (GVHD) and exposure keratopathy – 6 eyes (4 %); post refractive surgery keratoectasia – 4 eyes (3 %), and high refractive error – 3 eyes (2 %). Results Mean follow up was 27.5 months (range 1–71), mean wearing time in successful wearers group was 12.2 hours per day (range 10–16), mean wearing time in group of wearers who dropped out using GP-SCL, was 5.8 hours (range 3–8). Keratoconus patients achieved median best corrected visual acuity (BCVA) of 20/32, 84 % of patients achieved BCVA of 20/40 or more. The post keratoplasty group achieved median BCVA of 20/25, 92 % of patients achieved BCVA of 20/40 or better. In the other groups, median BCVA was as follows: ocular surface disorders – 20/50, keratoectasia – 20/30, high refractive error – 20/32. Positive fluid-venting was highly associated with successful GP-SCL wearing. Twenty patients (21 %) failed to wear GP-SCL. Conclusions GP-SCL's expand the management of various corneal abnormalities. The main indication for GP-SCL is optical correction of an irregular corneal surface, especially keratoconus and corneal transplant.

  8. 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

  9. 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

  10. Occupational allergic contact dermatitis to chromium from cement: Estimating the size of the problem in Australia.

    PubMed

    Wong, Celestine C; Gamboni, Sarah E; Palmer, Amanda M; Nixon, Rosemary L

    2015-11-01

    Allergic contact dermatitis (ACD) caused by chromium in cement is a significant occupational hazard. However, legislation in Europe over the past two decades to reduce the concentration of chromium in cement to <2 ppm through the addition of ferrous sulphate to cement, has seen a significant decrease in the incidence of chromium allergy. No such legislation exists in Australia. A retrospective analysis of results from the Patchcams database of patients attending the Occupational Dermatology Clinic at the Skin & Cancer Foundation, Melbourne, who were patch tested for chromium between 1 January 1993 to 31 December 2013, was conducted. Our review revealed that there has not been any significant change in the number of cases of ACD to chromium attributed to sensitisation through cement. Based on our data, we estimate that a minimum of 24 cases of chromium occupational ACD (OACD) from cement is found in Australia yearly, causing considerable morbidity, often associated with an inability to work, costly workers' compensation claims and sometimes the development of the disabling condition, persistent post-occupational dermatitis. These findings highlight the need for high-level discussions about adopting European legislation in Australia in order to reduce the likelihood of developing chromium OACD from cement. © 2014 The Australasian College of Dermatologists.

  11. 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.

  12. 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.

  13. Problems of dynamic fracture mechanics without contact of the crack faces

    NASA Astrophysics Data System (ADS)

    Guz', A. N.; Zozulya, V. V.

    1994-10-01

    In this, the first part of the survey we have discussed only certain aspects of dynamic fracture mechanics. The surveyed material has been selected with a preference for the most highly developed parts of the theory, specifically those elements which have direct bearing on the second part of the survey. We have also included information on the dynamic fracture mechanics of initially stressed materials, in the development of which one of the authors has been a major contributor. Since many problems of dynamic fracture mechanics have been overlooked in the survey, we have added supplementary references to the literature. Various aspects of the strength and fracture of materials under dynamic loading are set forth in [11, 12, 40, 57, 60, 73, 80, 83]. Criteria of the initiation, motion, branching, and arrest of cracks are discussed in [7, 9, 60, 102, 111, 113, 124]. Among the most interesting elements of dynamic fracture mechanics are the problems of crack propagation. Certain analytical results pertinent to this topic have been obtained in [43-45, 47, 67-72, 78, 87, 92, 96, 97].

  14. Electro-mechanical properties of composite materials for high-current contact applications

    NASA Astrophysics Data System (ADS)

    Jaćimović, J.; Felberbaum, L.; Giannini, E.; Teyssier, J.

    2014-03-01

    We report a detailed study that compares various composite materials (CM): Ag/ZnO, Ag/SnO2, Ag/C, Ag/WC, Ag/WC-C and Ag/Ni used in high-current dc circuit breaker applications. Their structural, mechanical, electrical and wetting properties were investigated. In parallel, switching operation tests on the same compounds were performed on commercial high-speed circuit breakers under real conditions (30 kA-900 V). A correlation between the microscopic variables and switching performances of the CMs was established. Materials like Ag/WC and Ag/WC-C were found to be unsuitable for the reliable functionality of the device. In contrast, Ag/C and Ag/SnO2 materials with high electrical and high thermal conductivity revealed remarkably good behaviour during switching operation tests.

  15. 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

  16. 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.

  17. An analytical solution of a one-dimensional thermal contact conductance problem with one heat flux and one insulated boundary condition

    SciTech Connect

    Tsai, Y.M.; Crane, R.A. )

    1992-05-01

    Heat transfer across surfaces in imperfect contact occurs in many practical situations. Since the thermal contact conductance problem has appeared in the literature, substantial efforts have been made to estimate the thermal conductance across the interface. Some of the techniques recently developed of estimating thermal contact conductance are based on experimental temperature data at one or several interior positions of the contacting solids and the calculation of the temperature at these locations for known contact conductance. Consequently, an accurate and efficient method for computing temperature distributions because quite important. FDM and FEM are most widely used. However, for most contact conductance computation methods, only the temperatures at the contacting regions and several other positions near the interface need to be determined, so the general FDM and FEM are not particularly efficient in solving this problem. This paper presents an analytical temperature distribution solution to the one-dimensional symmetric system with heat flux on one outside surface and insulation on the other. This analysis provides a theoretical basis for transient measurement of thermal contact conductance. While it is common practice in steady-state measurements to use a water-cooled heat sink, it is possible to limit the transient solution to time interval prior to any detectable temperature increase at the cold end. This effectively eliminates the need for water cooling and permits the use of an insulated boundary. The analytical solution to the mentioned problem obtained shows that for a symmetric system the temperature distribution solution includes two sets of distinct eigenfunctions.

  18. On one contact problem of plane elasticity for a doubly connected domain: application to a hexagon

    NASA Astrophysics Data System (ADS)

    Odishelidze, N.; Criado-Aldeanueva, F.; Criado, F.; Sanchez, J. M.

    2013-02-01

    The paper addresses a problem of plane elasticity theory for a doubly connected body whose external boundary is a regular hexagon boundary, and the internal boundary is the required full-strength hole including the origin of coordinates. Hexagon's two vertices are laid at the axis Oy, and the middle points of its two opposite sides are laid at the axis Ox. This full-strength hole is cycle symmetric. It is assumed that to every link of the broken line of the outer boundary of the given body are applied absolutely smooth rigid stamps with rectilinear bases, which are under action of the force P that applies to their middle points. There is no friction between the surface of given elastic body and stamps. The unknown full-strength contour is free from outer actions. Using the methods of complex analysis, the analytical image of Kolosov-Muskhelishvili's complex potentials (characterizing an elastic equilibrium of the body) and unknown parts of its boundary are determined under the condition that the tangential normal moment arising at it takes a constant value. Such holes are called full-strength holes. Numerical analysis are also performed and the corresponding graphs are constructed.

  19. [Some problems existing in current Chinese-English dictionaries of TCM nouns].

    PubMed

    Li, Yong-an; Li, Jing-yun

    2006-02-01

    The paper discusses some problems existing in the current Chinese-English dictionaries of TCM nouns, points out their negative effects, hoping that people will attach great importance to the problems. Meanwhile the author puts forth the urgency of compiling high quality Chinese-English TCM dictionaries, and the role of such dictionaries in the standardization of English translation of TCM nouns.

  20. 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.

  1. 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.

  2. Effects of tissue conductivity and electrode area on internal electric fields in a numerical human model for ELF contact current exposures

    NASA Astrophysics Data System (ADS)

    Tarao, H.; Kuisti, H.; Korpinen, L.; Hayashi, N.; Isaka, K.

    2012-05-01

    Contact currents flow through the human body when a conducting object with different potential is touched. There are limited reports on numerical dosimetry for contact current exposure compared with electromagnetic field exposures. In this study, using an anatomical human adult male model, we performed numerical calculation of internal electric fields resulting from 60 Hz contact current flowing from the left hand to the left foot as a basis case. Next, we performed a variety of similar calculations with varying tissue conductivity and contact area, and compared the results with the basis case. We found that very low conductivity of skin and a small electrode size enhanced the internal fields in the muscle, subcutaneous fat and skin close to the contact region. The 99th percentile value of the fields in a particular tissue type did not reliably account for these fields near the electrode. In the arm and leg, the internal fields for the muscle anisotropy were identical to those in the isotropy case using a conductivity value longitudinal to the muscle fibre. Furthermore, the internal fields in the tissues abreast of the joints such as the wrist and the elbow, including low conductivity tissues, as well as the electrode contact region, exceeded the ICNIRP basic restriction for the general public with contact current as the reference level value.

  3. 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.

  4. The Current Often Implemented Fitness Tests in Physical Education Programs: Problems and Future Directions

    ERIC Educational Resources Information Center

    Keating, Xiaofen Deng

    2003-01-01

    This paper aims to examine current nationwide youth fitness test programs, address problems embedded in the programs, and possible solutions. The current Fitnessgram, President's Challenge, and YMCA youth fitness test programs were selected to represent nationwide youth fitness test programs. Sponsors of the nationwide youth fitness test programs…

  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. [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.

  8. Average contact temperature and morphological details of the worn surface of copper based materials under high current density sliding against steel

    NASA Astrophysics Data System (ADS)

    Fadin, V. V.; Aleutdinova, M. I.; Kulikova, O. A.

    2016-11-01

    Dry sliding of copper and sintered composites of composition Cu-bearing steel against AISI steel 1045 under electric current of high contact density have been carried out. It is shown that the surface layer of copper and composites undergoes structural changes and tribolayer containing iron, copper and FeO oxide is formed. It is noted that the thin contact layer contains about 40 at % of oxygen and 40 at % Fe. Appearance of signs of a liquid phase is morphological feature of worn surface. It is established that contact temperature does not exceed 300°C. It allows claiming that melting of metals in tribolayer does not happen.

  9. Current transport mechanisms in Pt/Au Schottky contacts to AlInGaN using AlGaN/InGaN short-period superlattices

    NASA Astrophysics Data System (ADS)

    Xu, Feng; Chen, Peng; Xie, Zi-li; Xiu, Xiang-qian; Hua, Xue-mei; Shi, Yi; Zhang, Rong; Zheng, You-dou

    2017-05-01

    High-quality AlInGaN film grown by metal organic chemical vapor deposition is realized by fabricating the AlGaN/InGaN short-period superlattices, and then, Schottky contacts are fabricated on the AlInGaN superlattices. The crystal quality of AlInGaN superlattice samples is characterized by X-ray diffraction and scanning electron microscopy, and the correlation between the compositions of AlInGaN and growth condition is further clarified. The current transport mechanisms of the Pt/Au Schottky contacts to AlInGaN superlattice samples with different background carrier concentrations are studied by current-voltage (I -V) characteristics and theory analysis based on the thermionic emission (TE) and thermionic field emission (TFE) models. It is found that the results obtained from the TE and TFE models are almost identical for the Schottky contact to strain-balanced AlInGaN sample with low background carrier concentration, indicating that the thermionic emission is a dominant current transport mechanism. However, the Schottky contacts fabricated using high background carrier concentration AlInGaN samples demonstrate degraded barrier characteristics due to an occurrence of donor-like defects which result in the defect-assisted tunneling current, and thus, the combination of tunneling transport and thermionic emission constitutes the current transport mechanisms in Schottky contacts.

  10. 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.

  11. Personal stigma, problem appraisal and perceived need for professional help in currently untreated depressed persons.

    PubMed

    Schomerus, Georg; Auer, Charlotte; Rhode, Dieter; Luppa, Melanie; Freyberger, Harald J; Schmidt, Silke

    2012-06-01

    The role of stigma in help-seeking for depression is unclear. We hypothesize that in persons experiencing symptoms of depression, personal stigmatizing attitudes impair appraisal of the present condition as mental health problem and thus reduce the perceived need for professional help. We recruited a sample of 25 currently untreated depressed persons from the general population using local newspaper articles and emails that listed symptoms of depression avoiding the term "depression" or any other potentially stigma-associated term. We elicited personal stigmatizing attitudes, appraisal of the present problem as mental health problem, and perceived need for any medical or therapeutic help. In linear regression analyses controlling for depression severity and previous help-seeking, high personal stigma was related to lower problem appraisal (beta, -0.38; p<0.05) and to lower perceived need (beta, -0.59, p<0.01). Lower problem appraisal was associated with lower perceived need. Regressing need on both problem appraisal and stigma reduced the direct influence of stigma on need, indicating a partial mediation of this relationship by problem appraisal. Our small sample prohibited the use of path models. Personal stigmatizing attitudes in persons suffering from a depressive syndrome pose an important barrier to help, impairing appraisal of depressive symptoms as potential mental health problem and decreasing perceived need for professional help. Copyright © 2012 Elsevier B.V. All rights reserved.

  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. Peer Problems in Attention Deficit Hyperactivity Disorder: Current Status and Future Directions

    ERIC Educational Resources Information Center

    McQuade, Julia D.; Hoza, Betsy

    2008-01-01

    This article extends previous reviews regarding the peer problems of children with Attention Deficit Hyperactivity Disorder (ADHD) in several ways. In addition to summarizing past and current literature regarding the social behaviors of children with ADHD, these behaviors are discussed in terms of subtype and gender differences and treatment…

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

    USDA-ARS?s Scientific Manuscript database

    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...

  15. The Current State and Problems of the Upbringing Process Today: A Roundtable

    ERIC Educational Resources Information Center

    Russian Education and Society, 2006

    2006-01-01

    This article presents a roundtable discussion on the current state and problems of the upbringing process. The participants were professors from different universities in Russia. In his opening remarks, Zh.T. Toshchenko, editor in chief of Sotsiologicheskie issledovaniia and a corresponding member of the Russian Academy of Sciences, emphasized the…

  16. 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…

  17. [Neuroethics of pharmaceutical cognitive enhancement: the first ten years: current problems and practical guiding principles].

    PubMed

    Metzinger, T K

    2012-01-01

    An evaluating survey of the development of the neuroethics of pharmaceutical cognitive enhancement (PCE) during the last decade, focussing on the situation in Germany, has been undertaken. This article presents the most important conceptual problems, current substances and central ethical and legal issues. Very first guidelines and recommendations for policy-makers are formulated at the end of the text.

  18. 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…

  19. Semi-analytical solution to the 2014 eddy current benchmark problem

    NASA Astrophysics Data System (ADS)

    Miorelli, Roberto; Reboud, Christophe; Voulgaraki, Charitini; Poulakis, Nikolaos; Theodoulidis, Theodoros

    2015-03-01

    This work proposes a solution to the 2014 eddy current testing benchmark, published by the WFNDEC and proposed by the authors. The aim of this benchmark is to provide reference data for eddy current testing configurations involving magnetic sensors -here Hall sensors- as receivers, as they present some advantages in terms of resolution and sensitivity. After a presentation of the benchmark cases, the theoretical approach used to solve the equivalent electromagnetic problem is detailed and a alternative computation of eddy current signals is proposed. Then, simulations are quantitatively compared to experimental data in each case and the results are discussed.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

    Latino, Carl D.

    1992-09-01

    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.

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

    SciTech Connect

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

    2016-05-23

    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.

  3. 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.

  4. Plane contact problem on indentation of a flat punch into a transversely-isotropic half-plane with functionally graded transversely-isotropic coating

    NASA Astrophysics Data System (ADS)

    Vasiliev, A. S.; Volkov, S. S.; Aizikovich, S. M.; Mitrin, B. I.

    2017-02-01

    Plane contact problem of the theory of elasticity on indentation of a non-deformable punch with a flat base into an elastic transversely-isotropic half-plane with a transversely-isotropic functionally graded coating is considered. Elastic moduli of the coating vary with depth according to arbitrary functions. An approximated analytical solution effective for a whole range of geometrical parameter (relative layer thickness) of the problem is constructed. Some properties of the contact normal pressure under the punch are obtained analytically and illustrated by the numerical examples for a transversely-isotropic homogeneous and functionally graded coatings with different types of variation of elastic moduli with depth. The distinctions in distribution of contact normal pressure for homogeneous and functionally graded materials, coated and non-coated bodies are studied analytically and numerically.

  5. Influence of indium-tin-oxide thin-film quality on reverse leakage current of indium-tin-oxide/n-GaN Schottky contacts

    NASA Astrophysics Data System (ADS)

    Wang, R. X.; Xu, S. J.; Djurišić, A. B.; Beling, C. D.; Cheung, C. K.; Cheung, C. H.; Fung, S.; Zhao, D. G.; Yang, H.; Tao, X. M.

    2006-07-01

    Indium-tin-oxide (ITO)/n-GaN Schottky contacts were prepared by e-beam evaporation at 200°C under various partial pressures of oxygen. X-ray photoemission spectroscopy and positron beam measurements were employed to obtain chemical and structural information of the deposited ITO films. The results indicated that the observed variation in the reverse leakage current of the Schottky contact and the optical transmittance of the ITO films were strongly dependent on the quality of the ITO film. The high concentration of point defects at the ITO-GaN interface is suggested to be responsible for the large observed leakage current of the ITO/n-GaN Schottky contacts.

  6. 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.

  7. Capillary forces exerted by liquid drops caught between crossed cylinders. A 3-D meniscus problem with free contact line

    NASA Technical Reports Server (NTRS)

    Patzek, T. W.; Scriven, L. E.

    1982-01-01

    The Young-Laplace equation is solved for three-dimensional menisci between crossed cylinders, with either the contact line fixed or the contact angle prescribed, by means of the Galerkin/finite element method. Shapes are computed, and with them the practically important quantities: drop volume, wetted area, capillary pressure force, surface tension force, and the total force exerted by the drop on each cylinder. The results show that total capillary force between cylinders increases with decreasing contact angle, i.e. with better wetting. Capillary force is also increases with decreasing drop volume, approaching an asymptotic limit. However, the wetted area on each cylinder decreases with decreasing drop volume, which raises the question of the optimum drop volume to strive for, when permanent bonding is sought from solidified liquid. For then the strength of the bond is likely to depend upon the area of contact, which is the wetted area when the bonding agent was introduced in liquid form.

  8. Open problems of magnetic island control by electron cyclotron current drive

    NASA Astrophysics Data System (ADS)

    Grasso, D.; Lazzaro, E.; Borgogno, D.; Comisso, L.

    2016-12-01

    This paper reviews key aspects of the problem of magnetic islands control by electron cyclotron current drive in fusion devices. On the basis of the ordering of the basic spatial and time scales of the magnetic reconnection physics, we present the established results, highlighting some of the open issues posed by the small-scale structures that typically accompany the nonlinear evolution of the magnetic islands and constrain the effect of the control action.

  9. Open problems of magnetic island control by electron cyclotron current drive

    DOE PAGES

    Grasso, Daniela; Lazzaro, E.; Borgogno, D.; ...

    2016-11-17

    This study reviews key aspects of the problem of magnetic islands control by electron cyclotron current drive in fusion devices. On the basis of the ordering of the basic spatial and time scales of the magnetic reconnection physics, we present the established results, highlighting some of the open issues posed by the small-scale structures that typically accompany the nonlinear evolution of the magnetic islands and constrain the effect of the control action.

  10. Open problems of magnetic island control by electron cyclotron current drive

    SciTech Connect

    Grasso, Daniela; Lazzaro, E.; Borgogno, D.; Comisso, L.

    2016-11-17

    This study reviews key aspects of the problem of magnetic islands control by electron cyclotron current drive in fusion devices. On the basis of the ordering of the basic spatial and time scales of the magnetic reconnection physics, we present the established results, highlighting some of the open issues posed by the small-scale structures that typically accompany the nonlinear evolution of the magnetic islands and constrain the effect of the control action.

  11. Contact dermatitis to para-phenylenediamine in hair dye following sensitization to black henna tattoos - an ongoing problem.

    PubMed

    Kind, Fabiola; Scherer, Kathrin; Bircher, Andreas J

    2012-08-01

    The increased frequency of case reports of allergic contact dermatitis from non-permanent black henna tattoos in recent years shows the popularity of this form of body painting. Seven patients presented with allergic contact dermatitis after initial hair or eyelash dyeing. They all had a history of a previous reaction from a black henna tattoo. All were patch tested with the European standard patch test series and the standard supplemental series, as well as special series for dyes and hairdressers. All seven patients showed a positive reaction in patch testing with para-phenylenediamine (PPD) (0.3 % and/or 1.0 % in pet.). Five patients also had positive reactions to other dyes such as aminophenol, para-toluene diamine, disperse orange and yellow and four patients reacted to benzocaine. These were interpreted as cross-reactions. The time from sensitization by the black henna tattoo to the onset of allergic contact dermatitis after hair dyeing was an average of 6.2 years. The most common cause of allergic contact dermatitis after black henna tattoos is PPD. Both the long skin contact and the high concentrations of PPD increase the risk of sensitization. Allergic contact dermatitis may be followed by post-inflammatory hyper- or hypopigmentation, scarring and lifelong sensitization, which can have occupational impact, especially for hair dressers and cosmeticians. © The Authors • Journal compilation © Blackwell Verlag GmbH, Berlin.

  12. Impact of contact pressure-induced spectral changes on soft-tissue classification in diffuse reflectance spectroscopy: problems and solutions.

    PubMed

    Cugmas, Blaž; Bregar, Maksimilijan; Bürmen, Miran; Pernuš, Franjo; Likar, Boštjan

    2014-03-01

    Review of the existing studies on the contact pressure-induced changes in the optical properties of biological tissues showed that the reported changes in transmittance, reflectance, absorption, and scattering coefficient are vastly inconsistent. In order to gain more insight into the contact pressure-induced changes observed in biomedical applications involving common probe-spectrometer diffuse reflectance measurement setups and provide a set of practical guidelines minimizing the influence of the changes on the analysis of acquired spectra, we conducted a series of in vivo measurements, where the contact pressure was precisely controlled, and the spectral and contact pressure information were acquired simultaneously. Classification of three measurement sites on a human hand, representing the natural variability in the perfusion and structure of the underlying tissue, was assessed by training and evaluating classifiers at different contact pressure levels and for different probe operators. Based on the results, three practical guidelines have been proposed to avoid classification performance degradation. First, the most suitable pressure level should be identified. Second, the pressure level should be kept in a narrow range during the acquisition of spectra. Third, applications utilizing probes equipped with a calibrated spring can use several classifiers trained at different contact pressure levels to improve classification performance.

  13. [Contact glass tonometer].

    PubMed

    Kanngiesser, H; Robert, Y; Dekker, P

    1996-10-01

    This paper present a tonometer incorporated in a contact lens, which allows simultaneous measurement of intraocular pressure and performance ophthalmoscopy. The tonometer can record the pulse curve continuously, which can give us an indication of any circulatory problem. The device is therefore expected to yield additional information useful for the diagnosis of early glaucoma. Te device has three force sensors built in, which allow continuous measurement of the force exerted on the eye surface by the contact lens. The force of the contact lens on the eye can be altered and makes the adjustment of different eye pressures possible. These induced changes of the eye pressure and their influence on the fundus can be checked. We have taken some measurements on enucleated human eyes to compare our device with a Statham tansducer in the vitreous. We found a good correlation. We are currently taking measurements in volunteers. The clinical relevance of these observations and measurements will be examined in a future study.

  14. 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.

  15. Current prevalence rate of latex allergy: Why it remains a problem?

    PubMed Central

    Wu, Miaozong; McIntosh, James; Liu, Jian

    2016-01-01

    Objectives: This article aims to review the current prevalence rate of latex allergy among healthcare workers, susceptible patients, and the general public, and to investigate why latex is still a ubiquitous occupational health hazard. Methods: Scientific publications on PubMed, particularly those published within the last five years, and current regulations from agencies such as Food and Drug Administration (FDA) were reviewed. Consumer and commercial products that may contain latex were also surveyed. Results: Approximately 12 million tons of natural rubber latex is produced annually and is widely used to manufacture millions of consumer and commercial products. Only limited number of latex-derived products have been approved and regulated by government agencies, such as FDA, whereas the majority of finished products do not label whether they contain latex. Owing to millions of unidentifiable products containing latex and many routes for exposure to latex, preventing contact with latex allergens and reducing the prevalence of latex allergy are more difficult than expected. Reported data suggest that the average prevalence of latex allergy worldwide remains 9.7%, 7.2%, and 4.3% among healthcare workers, susceptible patients, and general population, respectively. Conclusions: Latex-derived products are ubiquitous, and latex allergy remains a highly prevalent health risk in many occupations and to the general population. Developing alternative materials and increasing the ability to identify and label latex-derived products will be practicable approaches to effectively control the health risks associated with latex. PMID:27010091

  16. Current prevalence rate of latex allergy: Why it remains a problem?

    PubMed

    Wu, Miaozong; McIntosh, James; Liu, Jian

    2016-05-25

    This article aims to review the current prevalence rate of latex allergy among healthcare workers, susceptible patients, and the general public, and to investigate why latex is still a ubiquitous occupational health hazard. Scientific publications on PubMed, particularly those published within the last five years, and current regulations from agencies such as Food and Drug Administration (FDA) were reviewed. Consumer and commercial products that may contain latex were also surveyed. Approximately 12 million tons of natural rubber latex is produced annually and is widely used to manufacture millions of consumer and commercial products. Only limited number of latex-derived products have been approved and regulated by government agencies, such as FDA, whereas the majority of finished products do not label whether they contain latex. Owing to millions of unidentifiable products containing latex and many routes for exposure to latex, preventing contact with latex allergens and reducing the prevalence of latex allergy are more difficult than expected. Reported data suggest that the average prevalence of latex allergy worldwide remains 9.7%, 7.2%, and 4.3% among healthcare workers, susceptible patients, and general population, respectively. Latex-derived products are ubiquitous, and latex allergy remains a highly prevalent health risk in many occupations and to the general population. Developing alternative materials and increasing the ability to identify and label latex-derived products will be practicable approaches to effectively control the health risks associated with latex.

  17. Advanced model of eddy-current NDE inverse problem with sparse grid algorithm

    NASA Astrophysics Data System (ADS)

    Zhou, Liming; Sabbagh, Harold A.; Sabbagh, Elias H.; Murphy, R. Kim; Bernacchi, William

    2017-02-01

    In model-based inverse problem, some unknown parameters need to be estimated. These parameters are used not only to characterize the physical properties of cracks, but also to describe the position of the probes (such as lift off and angles) in the calibration. After considering the effect of the position of the probes in the inverse problem, the accuracy of the inverse result will be improved. With increasing the number of the parameters in the inverse problems, the burden of calculations will increase exponentially in the traditional full grid method. The sparse grid algorithm, which was introduced by Sergey A. Smolyak, was used in our work. With this algorithm, we obtain a powerful interpolation method that requires significantly fewer support nodes than conventional interpolation on a full grid. In this work, we combined sparse grid toolbox TASMANIAN, which is produced by Oak Ridge National Laboratory, and professional eddy-current NDE software, VIC-3D R◯, to solve a specific inverse problem. An advanced model based on our previous one is used to estimate length and depth of the crack, lift off and two angles of the position of probes. Considering the calibration process, pseudorandom noise is considered in the model and statistical behavior is discussed.

  18. [The current problems and cross-cultural perspectives of patient-doctor relation: an overview].

    PubMed

    Koch, Eckhardt; Turgut, Tolga

    2004-01-01

    The success of the treatment in medicine, especially in psychiatry is based on the form and the strength of the patient-doctor relation. This complex and dynamic relation is changing in accordance with the social and technological development of the society. The context of the patient-doctor relation is determined by the present day culture as well as the traditional background. An overview of current patient-doctor relation and of problems that physicians and in particular psychiatrists meet is presented. Physicians have responsibilities in building patient-doctor relation. The ethical and legal aspects of these responsibilities are presented. The former paternalistic type of patient-doctor relation is evolving into a more equal and democratic relation. New problems are being encountered continuously in the changing process. Beside the of the process itself, the effects of progress in medical technology and communication systems on patient-doctor relation and the pressure, put from the insurance companies and/or authorities on physicians, which impair the trust between the physician and his patient, are making the process more difficult. The issues of compliance, sexual harassment and unique problems of patient-doctor relations in psychiatry are the other subtopics in the article. The cross-cultural aspects of patient-doctor relations and encountered clinical problems are discussed with case examples particularly about Turkish immigrants, who live in Germany. Suggestions for psychiatrists in Germany to work out the challenges facing them are presented in the conclusion.

  19. Distributed point source method for the modeling of a three-dimensional eddy current NDE problem

    NASA Astrophysics Data System (ADS)

    Bore, T.; Joubert, P.-Y.; Placko, D.

    2014-03-01

    This paper deals with modeling in electromagnetism in the field of eddy current for Non Destructive Evaluation. Several techniques could be used to diagnose structural damages. In eddy current application, a magnetic field generates by an excitation coil (or primary coil), interacts with a conductive target and generates eddy current. Variations in the phase and the magnitude of these eddy currents can be monitored using a second "receiver" coil. Variations in the physical properties (electrical conductivity, magnetic permeability,..) or the presence of any flaw in the target will cause a change in eddy current and a corresponding change in the phase and amplitude of measured signal. The interpretation of the signals requires a good understanding of the interaction between eddy current and structure. Therefore, researchers need analytical or numerical techniques to obtain a clear understanding of wave propagation behaviors. However, modeling of wave scattering phenomenon by conventional numerical techniques such as finite elements requires very fine mesh and heavy computational power. To go further, an innovative implementation of a semi-analytical modeling method, called the Distributed Points Source Method (DPSM), has been developed and used. The DPSM has already shown great potentialities for the versatile and computationally efficient modeling of complex electrostatic, electromagnetic or ultrasounic problems. In this paper, we report on a new implementation of the DPSM, called differential DPSM, which shows interesting prospects for the modeling of complex eddy current problems. In parallel, an Eddy Current Imager (ECI) has been recently developed in our laboratory in the aim of imaging cracks in metallic structures. In this paper, a simplified modeling of the ECI is presented using DPSM technique, the basics of DPSM formalism being firstly developed. A comparison between experimental and computed data obtained for a millimetric surface defect is presented in

  20. Current fouling problems of PVC film fills and research into new designs to eliminate fouling

    SciTech Connect

    Whittemore, M.R. ); Massey, T. )

    1992-01-01

    The fouling of film fills in power plant cooling towers represents a major problem in loss of performance of the cooling tower and loss of efficiency of the power plant. The results of this loss in performance is higher energy consumption to drive the fans to move air through the cooling tower in mechanical draft towers. Higher fuel consumption in plant operations or reduced peak load output and the discharge of warmer water which poses environmental concerns to our rivers and lakes. This paper discusses the effects of fouling on cooling tower performance and the current knowledge of how this fouling may occur, industry practices of controlling cleaning and eliminating the problem using new film fill products.

  1. The current spectrum of contact sensitization in patients with chronic leg ulcers or stasis dermatitis - new data from the Information Network of Departments of Dermatology (IVDK).

    PubMed

    Erfurt-Berge, Cornelia; Geier, Johannes; Mahler, Vera

    2017-09-01

    Patients with lower leg dermatitis, chronic venous insufficiency or chronic leg ulcers have a high prevalence of contact sensitization. To identify the current spectrum of contact allergens in these patients. Data of the Information Network of Departments of Dermatology on 5264 patients with the above diagnoses from the years 2003 to 2014 (study group) were compared with data on 4881 corresponding patients from 1994 to 2003 (historical control group) and with a current control group without these diagnoses (n = 55 510). Allergic contact dermatitis was diagnosed less frequently in the study group than in the historical control group (25.9% versus 16.9%; p < 0.001), and contact sensitization to most allergens had declined. The allergen spectrum, however, was largely unchanged. Important allergens are Myroxylon pereirae (balsam of Peru) (14.8% positive reactions), fragrance mix I (11.4%), lanolin alcohol (7.8%), colophonium (6.6%), neomycin sulfate (5.0%), cetearyl alcohol (4.4%), oil of turpentine (3.1%), and paraben mix (2.6%). Patch testing with additional series showed sensitization to Amerchol L-101 (9.7%), tert-butyl hydroquinone (8.7%), framycetin sulfate (5.0%), and gentamicin sulfate (3.1%). Topical preparations for treating the above-mentioned conditions should not contain fragrances, Myroxylon pereirae, and colophonium. The special allergen spectrum has to be considered in patch testing. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Problem-Based Learning Research in Anesthesia Teaching: Current Status and Future Perspective

    PubMed Central

    Chilkoti, G.; Mohta, M.; Wadhwa, R.; Saxena, A. K.

    2014-01-01

    The teaching curriculum in anesthesia involves traditional teaching methods like topic-based didactic lectures, seminars, and journal clubs; intraoperative apprenticeship; and problem-based learning (PBL) and simulation. The advantages of incorporating PBL in anesthesia teaching include development of skills like clinical reasoning, critical thinking, and self-directed learning; in addition it also helps in developing a broader perspective of case scenarios. The present paper discusses the characteristics, key elements, and goals of PBL; various PBL methods available; lacunae in the existing knowledge of PBL research; its current status and future perspectives in anesthesia teaching. PMID:24982673

  3. Storage and treatment of SNF of Alfa class nuclear submarines: current status and problems

    SciTech Connect

    Ignatiev, Sviatoslav; Zabudko, Alexey; Pankratov, Dmitry; Somov, Ivan; Suvorov, Gennady

    2007-07-01

    Available in abstract form only. Full text of publication follows: The current status and main problems associated with storage, defueling and following treatment of spent nuclear fuel (SNF) of Nuclear Submarines (NS) with heavy liquid metal cooled reactors are considered. In the final analysis these solutions could be realized in the form of separate projects to be funded through national and bi- and multilateral funding in the framework of the international collaboration of the Russian Federation on complex utilization of NS and rehabilitation of contaminated objects allocated in the North-West region of Russia. (authors)

  4. 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.

  5. An boldsymbol{E} -based mixed formulation for a time-dependent eddy current problem

    NASA Astrophysics Data System (ADS)

    Acevedo, Ramiro; Meddahi, Salim; Rodriguez, Rodolfo

    2009-12-01

    In this paper, we analyze a mixed form of a time-dependent eddy current problem formulated in terms of the electric field boldsymbol{E} . We show that this formulation admits a well-posed saddle point structure when the constraints satisfied by the primary unknown in the dielectric material are handled by means of a Lagrange multiplier. We use Nedelec edge elements and standard nodal finite elements to define a semi-discrete Galerkin scheme. Furthermore, we introduce the corresponding backward-Euler fully-discrete formulation and prove error estimates.

  6. Solution to the Eddy-Current Problem for Type-II Superconductors by Relaxation Method

    NASA Astrophysics Data System (ADS)

    Janíková, Edita; Slodička, Marián

    2008-09-01

    The fast developing industrial applications of superconductors require rigorous mathematical models of their physical behaviour and efficient numerical methods to solve them. We propose and study theoretically a new approximation scheme to solve the 3D eddy-current problem of diffusion of the electric field in type-II superconductors. The method is based on the relaxation principle, where the nonlinear time- and space-dependent partial differential equation (PDE) is split into a linear time-independent PDE coupled with a nonlinear equation involving no partial derivatives.

  7. 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,…

  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. 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.

  10. Finite element solution of nonlinear eddy current problems with periodic excitation and its industrial applications☆

    PubMed Central

    Bíró, Oszkár; Koczka, Gergely; Preis, Kurt

    2014-01-01

    An efficient finite element method to take account of the nonlinearity of the magnetic materials when analyzing three-dimensional eddy current problems is presented in this paper. The problem is formulated in terms of vector and scalar potentials approximated by edge and node based finite element basis functions. The application of Galerkin techniques leads to a large, nonlinear system of ordinary differential equations in the time domain. The excitations are assumed to be time-periodic and the steady-state periodic solution is of interest only. This is represented either in the frequency domain as a finite Fourier series or in the time domain as a set of discrete time values within one period for each finite element degree of freedom. The former approach is the (continuous) harmonic balance method and, in the latter one, discrete Fourier transformation will be shown to lead to a discrete harmonic balance method. Due to the nonlinearity, all harmonics, both continuous and discrete, are coupled to each other. The harmonics would be decoupled if the problem were linear, therefore, a special nonlinear iteration technique, the fixed-point method is used to linearize the equations by selecting a time-independent permeability distribution, the so-called fixed-point permeability in each nonlinear iteration step. This leads to uncoupled harmonics within these steps. As industrial applications, analyses of large power transformers are presented. The first example is the computation of the electromagnetic field of a single-phase transformer in the time domain with the results compared to those obtained by traditional time-stepping techniques. In the second application, an advanced model of the same transformer is analyzed in the frequency domain by the harmonic balance method with the effect of the presence of higher harmonics on the losses investigated. Finally a third example tackles the case of direct current (DC) bias in the coils of a single-phase transformer. PMID

  11. Finite element solution of nonlinear eddy current problems with periodic excitation and its industrial applications.

    PubMed

    Bíró, Oszkár; Koczka, Gergely; Preis, Kurt

    2014-05-01

    An efficient finite element method to take account of the nonlinearity of the magnetic materials when analyzing three-dimensional eddy current problems is presented in this paper. The problem is formulated in terms of vector and scalar potentials approximated by edge and node based finite element basis functions. The application of Galerkin techniques leads to a large, nonlinear system of ordinary differential equations in the time domain. The excitations are assumed to be time-periodic and the steady-state periodic solution is of interest only. This is represented either in the frequency domain as a finite Fourier series or in the time domain as a set of discrete time values within one period for each finite element degree of freedom. The former approach is the (continuous) harmonic balance method and, in the latter one, discrete Fourier transformation will be shown to lead to a discrete harmonic balance method. Due to the nonlinearity, all harmonics, both continuous and discrete, are coupled to each other. The harmonics would be decoupled if the problem were linear, therefore, a special nonlinear iteration technique, the fixed-point method is used to linearize the equations by selecting a time-independent permeability distribution, the so-called fixed-point permeability in each nonlinear iteration step. This leads to uncoupled harmonics within these steps. As industrial applications, analyses of large power transformers are presented. The first example is the computation of the electromagnetic field of a single-phase transformer in the time domain with the results compared to those obtained by traditional time-stepping techniques. In the second application, an advanced model of the same transformer is analyzed in the frequency domain by the harmonic balance method with the effect of the presence of higher harmonics on the losses investigated. Finally a third example tackles the case of direct current (DC) bias in the coils of a single-phase transformer.

  12. 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…

  13. Contact dermatitis

    MedlinePlus

    Dermatitis - contact; Allergic dermatitis; Dermatitis - allergic; Irritant contact dermatitis; Skin rash - contact dermatitis ... There are 2 types of contact dermatitis. Irritant dermatitis: This ... can be by contact with acids, alkaline materials such as soaps ...

  14. 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.

  15. 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. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. 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.

  17. Contact allergy to hairdressing allergens in female hairdressers and clients--current data from the IVDK, 2003-2006.

    PubMed

    Uter, Wolfgang; Lessmann, Holger; Geier, Johannes; Schnuch, Axel

    2007-11-01

    Hair cosmetics, in particular hair dyes, bleaches, and permanent wave solutions, contain a number of potential contact allergens. The pattern of exposure to these in hairdressers, clients and home-users may change over time. Data on female patients who consulted centers of the Information Network of Departments of Dermatology (IVDK, http://www.ivdk.org) between 01/2003 and 12/2006 was analyzed. Patients were divided into a) hair-dressers, given they worked in this occupation and suffered from occupational skin disease (n = 480),and b) "clients",who never worked as hairdressers, but in whom hair cosmetics were considered a potential cause of contact dermatitis (n = 780). In hairdressers, the most important allergens were ammonium persulfate (21.7% positive),p-toluenediamine (PTD,19.6% positive),p-phenylenedi-amine (PPD,18.1% positive) and, with decreasing time trend, glyceryl monothioglycolate (2005/2006 still 7.5% positive). Biocides must be regarded as important allergens in hairdressers, namely,(chloro) methylisothiazolinone and methyldibromoglutaronitrile. Clients, who were considerably older on average, had possibly been tested in a more aimed fashion, yielding (strikingly) higher sensitization prevalences to a number of allergens of oxidative hair dyes such as PPD or PTD. The continual analysis of sensitization prevalences in patients patch tested can identify areas needing in-depth research and preventive intervention, such as avoiding the use of certain biocides in shampoo intended for professional use by hairdressers or further reducing the concentrations in oxidative hair dyes.

  18. Temporal Evaluation of Neurosensory Complications After Mandibular Third Molar Extraction: Current Problems for Diagnosis and Treatment

    PubMed Central

    Akashi, Masaya; Hiraoka, Yujiro; Hasegawa, Takumi; Komori, Takahide

    2016-01-01

    Objective: This retrospective study aimed to report the incidence of neurosensory complications after third molar extraction and also to identify current problems and discuss appropriate management of these complications. Method: Patients who underwent extraction of deeply impacted mandibular third molars under general anesthesia were included. The following epidemiological data were retrospectively gathered from medical charts: type of neurosensory complication, treatment for complication, and outcome. Results: A total 369 mandibular third molars were extracted in 210 patients under general anesthesia during this study period. Thirty-one of the 369 teeth (8.4%) in 31 patients had neurosensory complications during the first postoperative week resulting from inferior alveolar nerve damage. Neurosensory complications lasting from 1 to 3 months postoperatively included 17 cases of hypoesthesia and 8 of dysesthesia in 19 patients. Five cases of hypoesthesia and 4 of dysesthesia in 5 patients persisted over 1 year postoperatively. Sixteen of 369 teeth (4.3%) in 16 patients had persistent neurosensory complications after third molar extraction under general anesthesia. Stellate ganglion block was performed in 4 patients. Early initiation of stellate ganglion block (within 2 weeks postoperatively) produced better outcomes than late stellate ganglion block (over 6 months postoperatively). Conclusion: Refractory neurosensory complications after third molar extraction often combine both hypoesthesia and dysesthesia. Current problems in diagnosis and treatment included delayed detection of dysesthesia and the lack of uniform timing of stellate ganglion block. In the future, routinely inquiring about dysesthesia and promptly providing affected patients with information about stellate ganglion block might produce better outcomes. PMID:28217188

  19. Contact Lenses on Submarines

    DTIC Science & Technology

    2014-09-26

    NAVAL SUBMARINE MEDICAL RESEARCH LABORATORY SUBMARINE BASE, GROTON, CONN. REPORT NUMBER 1048 CONTACT LENSES ON SUBMARINES... CONTACT LENSES ON SUBMARINES by James F. Socks, CDR, MSC, USN NAVAL SUBMARINE MEDICAL RESEARCH LABORATORY REPORT NUMBER 1048 NAVAL MEDICAL RESEARCH...DRSCHLAB Approved for public release; distribution unlimited SUMMARY PAGE PROBLEM To determine the feasibility of wearing contact lenses aboard

  20. Investigation of tunneling current and local contact potential difference on the TiO2(110) surface by AFM/KPFM at 78 K

    NASA Astrophysics Data System (ADS)

    Wen, Huan Fei; Li, Yan Jun; Arima, Eiji; Naitoh, Yoshitaka; Sugawara, Yasuhiro; Xu, Rui; Hai Cheng, Zhi

    2017-03-01

    We propose a new multi-image method for obtaining the frequency shift, tunneling current and local contact potential difference (LCPD) on a TiO2(110) surface with atomic resolution. The tunneling current image reveals rarely observed surface oxygen atoms contrary to the conventional results. We analyze how the surface and subsurface defects affect the distribution of the LCPD. In addition, the subsurface defects are observed clearly in the tunneling current image, in contrast to a topographic image. To clarify the origin of the atomic contrast, we perform site-dependent spectroscopy as a function of the tip–sample distance. The multi-image method is expected to be widely used to investigate the charge transfer phenomena between the nanoparticles and surface sites, and it is useful for elucidating the mechanisms of catalytic reactions.

  1. Investigation of tunneling current and local contact potential difference on the TiO2(110) surface by AFM/KPFM at 78 K.

    PubMed

    Wen, Huan Fei; Li, Yan Jun; Arima, Eiji; Naitoh, Yoshitaka; Sugawara, Yasuhiro; Xu, Rui; Cheng, Zhi Hai

    2017-03-10

    We propose a new multi-image method for obtaining the frequency shift, tunneling current and local contact potential difference (LCPD) on a TiO2(110) surface with atomic resolution. The tunneling current image reveals rarely observed surface oxygen atoms contrary to the conventional results. We analyze how the surface and subsurface defects affect the distribution of the LCPD. In addition, the subsurface defects are observed clearly in the tunneling current image, in contrast to a topographic image. To clarify the origin of the atomic contrast, we perform site-dependent spectroscopy as a function of the tip-sample distance. The multi-image method is expected to be widely used to investigate the charge transfer phenomena between the nanoparticles and surface sites, and it is useful for elucidating the mechanisms of catalytic reactions.

  2. Candidate sites of action for microdosimetry associated with exposure to extremely-low-frequency magnetic fields, electric fields and contact currents.

    PubMed

    Sastre, Antonio; Kavet, Robert

    2002-09-01

    Recent advances enable one to apply numerical techniques to anatomically-correct human models to compute current densities and electric fields in tissue due to exposure to electric fields, magnetic fields, or contact currents. These methods have proved to be informative in estimating exceedance of basic restrictions prescribed by exposure guideline organizations. To date, the analyses have been conducted with a resolution on the order of millimeters. However, these techniques have future roles to play at higher levels of resolution at those sites in target tissues suspected of transducing local electric fields into biological responses. Two specific cases in which high resolution "microdosimetry" would yield value involve (a) residential settings and childhood leukemia and (b) worker exposure and cardiovascular disease. Recent research suggests that residential contact currents on the order of microamperes can produce biologically significant dose (expressed as the local electric field) to the bone marrow of a child. Microdosimetry would focus on pluripotent progenitor cells resident in the marrow compartment, as well as anatomic features that distinguish a child's from an adult's marrow. Laboratory and epidemiologic research has suggested that magnetic field exposure may affect heart rate variability, a measure reflective of autonomic nervous system control of cardiac activity. Given the physical attributes of the central nervous system and the sites that could serve as substrates for field interactions, future microdosimetry addressing heart rate variability effects may be well-advised to focus on the electrically excitable dendritic arborizations of neurons. In both cases, microdosimetry will help shed light on primary interactions in tissue.

  3. A review of childhood abuse, health, and pain-related problems: the role of psychiatric disorders and current life stress.

    PubMed

    Sachs-Ericsson, Natalie; Cromer, Kiara; Hernandez, Annya; Kendall-Tackett, Kathleen

    2009-01-01

    The current article reviews recent research demonstrating the relationship between childhood physical and sexual abuse and adult health problems. Adult survivors of childhood abuse have more health problems and more painful symptoms. We have found that psychiatric disorders account for some, but not all, of these symptoms, and that current life stress doubles the effect of childhood abuse on health problems. Possible etiologic factors in survivors' health problems include abuse-related alterations in brain functioning that can increase vulnerability to stress and decrease immune function. Adult survivors are also more likely to participate in risky behaviors that undermine health or to have cognitions and beliefs that amplify health problems. Psychiatric disorders, although not the primary cause of difficulties, do have a role in exacerbating health and pain-related problems. We conclude by outlining treatment recommendations for abuse survivors in health care settings.

  4. 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.

  5. 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

  6. Risk factors, testing and preventative strategies for non-contact injuries in professional football: current perceptions and practices of 44 teams from various premier leagues.

    PubMed

    McCall, Alan; Carling, Chris; Nedelec, Mathieu; Davison, Michael; Le Gall, Franck; Berthoin, Serge; Dupont, Gregory

    2014-09-01

    Little is known about injury prevention practices in professional football clubs. The purpose of this study was therefore to determine the current perceptions and practices of premier league football clubs internationally concerning risk factors, testing and preventative exercises for non-contact injuries. A survey was administered to 93 premier league football clubs internationally. The survey included four sections: (1) persons involved in the injury prevention programme: position, quantity, role, qualification; (2) perceptions regarding non-contact injury risk factors; (3) tests used to identify non-contact injury risk and (4) non-contact injury prevention exercises used, their perceived effectiveness and implementation strategies. 44 surveys were successfully returned (47%). The position of physiotherapist was the most represented position in the injury prevention programme. The top five perceived risk factors in rank order were previous injury, fatigue, muscle imbalance, fitness and movement efficiency. The five most commonly used tests to identify injury risk (in rank order) were functional movement screen, questionnaire, isokinetic dynamometry, physical tests and flexibility. The top five exercises used by clubs were (also in rank order) eccentric exercise, balance/proprioception, hamstring eccentric, core stability and, sharing the fifth position, Nordic hamstring and gluteus activation. The survey revealed the most common perceptions and practices of premier league football clubs internationally regarding risk factors, testing and preventative exercises. The findings can enable reduction of the gap between research and practice. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  7. 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

  8. 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.

  9. 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).

  10. Current orientation and contact distance dependence of rapid voltage oscillations in the organic conductor β''-[bis(ethylenedithio)tetrathiafulvalene]3(HSO4)2

    NASA Astrophysics Data System (ADS)

    Wakita, Hitoshi; Tamura, Kozo; Ozawa, Tatsuhiko; Bando, Yoshimasa; Kawamoto, Tadashi; Mori, Takehiko

    2010-12-01

    In an organic conductor β″-[bis(ethylenedithio)tetrathiafulvalene]3(HSO4)2, characteristic voltage oscillation is observed in the negative differential resistance region of the nonlinear conductivity below the metal-insulator transition at 125 K. The observed frequency f is 4-25 kHz and increases linearly with the collective current Jco. The oscillation appears in the two crystal directions of the conducting layer in agreement with the two-dimensional nonstripe charge order, where the anisotropy of the Jco/f slope is about two. The voltage oscillation disappears when the contact distance is larger than 0.02 cm, and at the same time the current-voltage characteristics loses a sharp negative resistance region. Since this critical length corresponds to the characteristic domain size of the charge order, the observed oscillation is interpreted by coherent transport of charge order which can move in different two directions.

  11. 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.

  12. Military aviation: a contact lens review.

    PubMed

    Lattimore, M R

    1990-10-01

    The military aviation communities have benefitted from the development of advanced electro-optical avionics systems. One drawback that has emerged is an increasing system incompatibility with traditional spectacle visual corrections. An alternative solution to the refractive error correction problem that some services have been investigating is that of contact lens wear. Since this much-debated topic is currently of command interest, a general overview of contact lens issues is presented as a framework for future discussions.

  13. On the periodic behavior of solutions to a diffusion problem describing currents in a high-temperature superconductor

    NASA Astrophysics Data System (ADS)

    Bauman, P.; Friesen, M.; Phillips, D.

    2000-03-01

    We study the large time behavior of solutions to a model describing the current flow in a type-II superconducting wire subject to a periodic transport current and a transverse applied magnetic field. The model is given as an initial value problem for an elliptic-degenerate parabolic equation on R2. We show that the current distributions are asymptotically periodic in time as t→∞.

  14. Hands-on defibrillation: an analysis of electrical current flow through rescuers in direct contact with patients during biphasic external defibrillation.

    PubMed

    Lloyd, Michael S; Heeke, Brian; Walter, Paul F; Langberg, Jonathan J

    2008-05-13

    Brief interruptions in chest compressions reduce the efficacy of resuscitation from cardiac arrest. Interruptions of this type are inevitable during hands-off periods for shock delivery to treat ventricular tachyarrhythmias. The safety of a rescuer remaining in contact with a patient being shocked with modern defibrillation equipment has not been investigated. This study measured the leakage voltage and current through mock rescuers while they were compressing the chests of 43 patients receiving external biphasic shocks. During the shock, the rescuer's gloved hand was pressed onto the skin of the patient's anterior chest. To simulate the worst case of an inadvertent return current pathway, a skin electrode on the rescuers thigh was connected to an electrode on the patient's shoulder. In no cases were shocks perceptible to the rescuer. Peak potential differences between the rescuer's wrist and thigh ranged from 0.28 to 14 V (mean 5.8+/-5.8 V). The average leakage current flowing through the rescuer's body for each phase of the shock waveform was 283+/-140 microA (range 18.9 to 907 microA). This was below several recommended safety standards for leakage current. Rescuers performing chest compressions during biphasic external defibrillation are exposed to low levels of leakage current. The present findings support the feasibility of uninterrupted chest compressions during shock delivery, which may enhance the efficacy of defibrillation and cardiocerebral resuscitation.

  15. Astronomical Site in the Ukraine: Current Status and Problems of Preservation

    NASA Astrophysics Data System (ADS)

    Vavilova, I. B.; Karetnikov, V. G.; Konovalenko, A. A.; Logvinenko, O. O.; Pinigin, G. I.; Steshenko, N. V.; Tarady, V. K.; Yatskiv, Ya. S.

    The present status of optical and radio astronomical sites in Ukraine and the problems of preservation are briefly reviewed. The problems of light pollution and the influence of thechnology can be solved using scientific and engeneering methods. However the main problem of preservation is the economic one of maintaining the infrastructure.

  16. THE CURRENT STATUS OF RESEARCH AND THEORY IN HUMAN PROBLEM SOLVING.

    ERIC Educational Resources Information Center

    DAVIS, GARY A.

    PROBLEM-SOLVING THEORIES IN THREE AREAS - TRADITIONAL (STIMULUS-RESPONSE) LEARNING, COGNITIVE-GESTALT APPROACHES, AND COMPUTER AND MATHEMATICAL MODELS - WERE SUMMARIZED. RECENT EMPIRICAL STUDIES (1960-65) ON PROBLEM SOLVING WERE CATEGORIZED ACCORDING TO TYPE OF BEHAVIOR ELICITED BY PARTICULAR PROBLEM-SOLVING TASKS. ANAGRAM,…

  17. 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.

  18. In-situ Generated Tribomaterial in Metal/Metal Contacts: current understanding and future implications for implants.

    PubMed

    Espallargas, N; Fischer, A; Muñoz, A Igual; Mischler, S; Wimmer, M A

    2017-06-01

    Artificial hip joints operate in aqueous biofluids that are highly reactive towards metallic surfaces. The reactivity at the metal interface is enhanced by mechanical interaction due to friction, which can change the near-surface structure of the metal and surface chemistry. There are now several reports in the literature about the in-situ generation of reaction films and tribo-metallurgical transformations on metal-on-metal hip joints. This paper summarizes current knowledge and provides a mechanistic interpretation of the surface chemical and metallurgical phenomena. Basic concepts of corrosion and wear are illustrated and used to interpret available literature on in-vitro and in-vivo studies of metal-on-metal hip joints. Based on this review, three forms of tribomaterial, characterized by different combinations of oxide films and organic layers, can be determined. It is shown that the generation of these tribofilms can be related to specific electrochemical and mechanical phenomena in the metal interface. It is suggested that the generation of this surface reaction layer constitutes a way to minimize (mechanical) wear of MoM hip implants.

  19. BISON Contact Improvements CASL FY14 Report

    SciTech Connect

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

    2014-09-01

    The BISON code is the foundation for multiple fuel performance modeling efforts, and is currently 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 solutions 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 questionable 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 sufficiently 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.

  20. [Ten years after German unification--current behavioural and emotional problems of adolescents in Germany].

    PubMed

    von Widdern, Susanne; Hässler, Frank; von Widdern, Olrik; Richter, Jörg

    2004-11-01

    Internalizing and externalizing problems based on Youth Self-Report (YSR) were investigated in an empirical sample of 371 students at the age of 13 until 18 years from common secondary and vocational schools in Rostock (Mecklenburg-Western Pomerania) in 2000/2001. Considering syndromes in comparison with other german and international empirical studies, internalizing and externalizing problems show high prevalence for both girls and boys. Nearly every fifth student judges themselves as within clinical range for psychiatric problems. Girls reported significant more internalizing problems (social withdrawal, somatic complaints, anxious/depressed). An interaction effect by age and sex for aggressive and delinquent behaviour was found with highest prevalence for boys at age 15/16. The frequency of internalizing problems and attention problems increases with adolescent's age. Low adolescent's education level, parental divorce and big size of siblings were associated with externalizing problems, whereas unemployment of the father was associated with depressive and social problems. Delinquent behaviour and attention problems are the most important predictors for negative school outcome like comparatively bad school achievement and low reading ability. The results suppose a possible increase in psychosocial problems of juvenile persons in eastern Germany one decade after German Unification, indicated the necessity of higher supply for preventive and therapeutic programs.

  1. The patient experience of sleep problems and their treatment in the context of current delusions and hallucinations.

    PubMed

    Waite, Felicity; Evans, Nicole; Myers, Elissa; Startup, Helen; Lister, Rachel; Harvey, Allison G; Freeman, Daniel

    2016-06-01

    There is increasing recognition that sleep problems are common in patients with psychosis, that they exacerbate delusions and hallucinations and should be a treatment target. The aim of this study was to gain a patient perspective on the nature of sleep problems in psychosis and experience of treatment. A qualitative, semi-structured interview-based study to explore patient accounts of sleep problems and associated psychological treatment. Ten patients with recent delusions and hallucinations, who had experienced sleep problems and received psychological treatment during a clinical trial (the Better Sleep Trial), were interviewed. Responses were analysed using interpretative phenomenological analysis. Patients reported experiencing problems of getting to sleep, staying asleep, too much sleep, nightmares, and erratic sleep patterns. These sleep problems caused emotional distress, fatigue, and reduction in daytime activities. Worry and psychotic experiences disturbed sleep, while consequent tiredness meant that patients coped poorly with voices and persecutory fears. Treatment for sleep problems was viewed very positively and considered to have wide-ranging impacts. Sleep disturbance is a major problem for patients with psychosis, which should be treated more often in services using evidence-based interventions. Psychological interventions for sleep problems are valued by patients with psychosis. Patients with current distressing psychotic experiences report wide-ranging benefits from a brief psychological intervention for sleep problems. © 2015 The Authors. Psychology and Psychotherapy published by John Wiley & Sons Ltd on behalf of the British Psychological Society.

  2. Problem of construction of the operator of the electromagnetic current of a nucleus

    SciTech Connect

    Korchin, A.Y.; Shebeko, A.V.

    1984-10-01

    The idea of R. G. Sachs (Phys. Rev. 74, 433 (1948)) in the phenomenological theory of exchange currents in nuclei is developed to obtain an expression for the Hamiltonian of a nucleus. An expression is obtained for the current which has the same isospin structure as the pion and seagull currents in the theory of meson exchange currents. Sachs' result follows for the case of point nucleons.

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

    SciTech Connect

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

    2016-05-16

    Herein, we report on achieving ultra-high electron density (exceeding 10{sup 14 }cm{sup −2}) in a GaN bulk material device by ionic liquid gating, through the application of atomic layer deposition (ALD) of Al{sub 2}O{sub 3} 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 10{sup 5} at room temperature. An ultra-high electron density exceeding 10{sup 14 }cm{sup −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.

  4. 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.

  5. A Review of Social Problem-Solving Interventions: Past Findings, Current Status, and Future Directions

    ERIC Educational Resources Information Center

    Merrill, Kristen L.; Smith, Stephen W.; Cumming, Michelle M.; Daunic, Ann P.

    2017-01-01

    Students with significant behavioral and social problems experience some of the poorest outcomes in school and beyond. It is imperative, therefore, that educational researchers and school-based professionals address the needs of students who exhibit maladaptive behavior to alter their poor outcome trajectory. Social problem-solving (SPS)…

  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. Reading Problems, Attentional Deficits, and Current Mental Health Status in Adjudicated Adolescent Males

    ERIC Educational Resources Information Center

    O'Brien, Natalie; Langhinrichsen-Rohling, Jennifer; Shelley-Tremblay, John

    2007-01-01

    This study examined the prevalence of reading problems and self-reported symptoms of attentional deficits in a sample of adjudicated adolescent males (N = 101) aged 12 to 18 years who were residing in an alternative sentencing residential program. Thirty-four percent of the youth had reading problems while only 9% of the boys had self-reported…

  8. 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,…

  9. Teaching Problem-Solving: Implications from Cognitive Development Research. AAHE-ERIC Higher Education Research Currents.

    ERIC Educational Resources Information Center

    Stonewater, Jerry K.; Stonewater, Barbara B.

    1984-01-01

    The relationship between cognitive development and problem-solving skills is discussed. One approach for improving students' problem-solving skills rests in the application of cognitive development theories to instruction. Instructional strategies that facilitate cognitive development can be categorized into two groups: instruction that challenges…

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

    PubMed Central

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

    2015-01-01

    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. PMID:27877812

  11. [Current situation and problems associated with inactivation of microorganisms in water using copper].

    PubMed

    Kishida, Naohiro; Simazaki, Dai; Kosaka, Koji; Kosuge, Ruka; Akiba, Michihiro; Hayashi, Kenji

    2013-09-01

    The current situation and problems associated with inactivation of microorganisms in water using copper were elucidated. A literature review was conducted regarding the history and mechanisms of inactivation technology using copper, the variety of microorganisms shown to be inactivated by these methods in previous experiments, and the efficacy of such technologies for the inactivation of microorganisms in water. The use of copper for inactivation of microorganisms has a long history. Although the use of copper was discontinued temporarily owing to the advent of antibiotics in the 1930s, the occurrence of antibiotic-resistant bacteria has resulted in the need for different approaches to control pathogenic microorganisms. One such alternative is the use of copper. Although the mechanisms underlying the efficacy of copper inactivation technology have not yet been elucidated in detail, it has been suggested that pathogenic bacteria are inactivated due to the toxicity of copper ions and strong oxidation effects of reactive oxygen species. Copper inactivation technology is effective against many pathogenic microorganisms that pose a risk to public health, such as Legionella pneumophila, Salmonella enterica, and Mycobacterium tuberculosis. In recent years, copper inactivation technology has been used in various water-related devices, especially water supply pipes in buildings. Previous studies have demonstrated that microorganisms can be sufficiently inactivated by copper even at concentrations below that specified in the Water Quality Standard for Drinking Water. However, some previous studies have indicated that the inactivation effect of copper is short-lived. Therefore, the development of techniques to maintain a long-term inactivation effect is a key concern. In addition, it has been reported that the use of copper pipes triggers chlorine decay and results in the formation of chlorine disinfection byproducts. Hence, further studies should aim at assessing the risks

  12. Current problems of dynamics of moons of planets and binary asteroids based on observations

    NASA Astrophysics Data System (ADS)

    Emel'yanov, N. V.

    2017-01-01

    The general approach to studying the dynamics of moons of planets and asteroids consists in developing more and more accurate models of motion based on observational data. Not only the necessary ephemerides, but also some physical parameters of planets and moons are obtained this way. It is demonstrated in the present study that progress in this field is driven not only by the increase in accuracy of observations. The accuracy of ephemerides may be increased by expanding the observation time interval. Several problems arise on the way toward this goal. Some of them become apparent only when the procedure of observational data processing and use is examined in detail. The method used to derive astrometric data by processing the results of photometric observations of mutual occultations and eclipses of planetary moons is explained below. The primary contribution to the error of astrometric results is produced by the unaccounted noise level in photometric readings and the inaccuracy of received values of the albedo of moons. It is demonstrated that the current methods do not allow one to eliminate the noise completely. Extensive additional photometric measurements should be performed at different angles of rotation of moons and in different spectral bands of the visible wavelength range in order to obtain correct values of the albedo of moons. Many new distant moons of the major planets have been discovered in the early 21st century. However, the observations of these moons are scarce and were performed over short time intervals; as a result, some of the moons were lost. The necessity of further observations of these Solar System bodies is pointed out in the present study. Insufficient knowledge of asteroid masses is an obstacle to improving the accuracy of the ephemerides of Mars. The basic method for determining the masses of large asteroids consists in analyzing their influence on the motion of Mars, the Earth, and spacecraft. The masses of more than 100 large

  13. 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.

  14. Inversion of Heavy Current Electroheat Problems on a Graphics Processing Unit (GPU)

    DTIC Science & Technology

    2013-11-10

    Genetic and Gradient-based Optimization Algorithms for Solving Electromagnetics Problem,” IEEE Trans. Magnetics, Vol. 31 (3), pp. 1932-1935, 1995...and the optimization, we use the GPU to perform the electroheat optimization by the genetic algorithm to achieve computational efficiencies better...part problem and the optimization, we use the GPU to perform the electroheat optimization by the genetic algorithm to achieve computational

  15. The "anthracene problem": closed-form conjugated-circuit models of ring currents in linear polyacenes.

    PubMed

    Fowler, Patrick W; Myrvold, Wendy

    2011-11-17

    Conjugated-circuit models for induced π ring currents differ in the types of circuit that they include and the weights attached to them. Choice of circuits for general π systems can be expressed compactly in terms of matchings of the circuit-deleted molecular graph. Variants of the conjugated-circuit model for induced π currents are shown to have simple closed-form solutions for linear polyacenes. Despite differing assumptions about the effect of cycle area, all the models predict the most intense perimeter current in the central rings, in general agreement with ab initio current-density maps. All tend to overestimate the rate of increase with N of the central ring current for the [N]polyacene, in comparison with molecular-orbital treatments using ipsocentric ab initio, pseudo-π, and Hückel-London approaches.

  16. Current ethical and other problems in the practice of African traditional medicine.

    PubMed

    Omonzejele, Peter

    2003-01-01

    Medicine in Africa is regarded as possessing its own "life force", not just using a system of prescribing. This is because health problems are not only attributed to pathological explanations alone, but also to other "forces". Hence, traditional healers utter incantations to take care of negative forces which militate against achieving cure. Treatment in African traditional medicine (ATM) is holistic. It seeks to strike a balance between the patients' body, soul and spirit. The problems arise from the infiltration of charlatans into the field, the practice of using mystical explanations for ill-health, and inadequate knowledge of the properties and clinical use of herbal remedies. Despite its problems, ATM can work in parallel with orthodox medicine using its strengths rather than its weaknesses. ATM has to be applied within a uniform ethical system. Practitioners of ATM must follow the principles of autonomy and confidentiality.

  17. Some Bubble and Contact Problems,

    DTIC Science & Technology

    1979-11-21

    motion, rather than Laplace’s equation which Rayleigh had used. The use of the wave equation to describe large amplitude motions was considered...Kolodner, to include surface tension, viscosity and an incident sound field, in the same way as Plesset and others had iodified Rayleigh’s equation ...difference p, the equilibrium configura- tion of the tube would be a cylinder, and we denoted by C its cross sectional curve. Then the equations of

  18. 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.)

  19. 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.)

  20. 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.

  1. AGRICULTURAL LABOR--THE PROBLEM, ATTEMPTS AT ORGANIZATION, CURRENT LAWS, AND WHAT ARE THE ISSUES.

    ERIC Educational Resources Information Center

    CALL, DAVID

    THE NUMBER OF HIRED FARM WORKERS IS DECREASING WITH THE INCREASED USE OF LABORSAVING FARM MACHINERY AND TECHNOLOGY WHICH ALLOWS GREATER OUTPUT PER WORKER. THE LOW WAGE SCALE PREVALENT IN AGRICULTURE IS THE MAJOR CAUSE OF THE FARM LABOR PROBLEM. WAGE RATES ARE DIFFICULT TO MEASURE ACCURATELY BECAUSE OF A GREAT DIVERSITY IN METHODS OF PAYMENT AND…

  2. 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…

  3. 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…

  4. AGRICULTURAL LABOR--THE PROBLEM, ATTEMPTS AT ORGANIZATION, CURRENT LAWS, AND WHAT ARE THE ISSUES.

    ERIC Educational Resources Information Center

    CALL, DAVID

    THE NUMBER OF HIRED FARM WORKERS IS DECREASING WITH THE INCREASED USE OF LABORSAVING FARM MACHINERY AND TECHNOLOGY WHICH ALLOWS GREATER OUTPUT PER WORKER. THE LOW WAGE SCALE PREVALENT IN AGRICULTURE IS THE MAJOR CAUSE OF THE FARM LABOR PROBLEM. WAGE RATES ARE DIFFICULT TO MEASURE ACCURATELY BECAUSE OF A GREAT DIVERSITY IN METHODS OF PAYMENT AND…

  5. 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…

  6. 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…

  7. 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

  8. 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.

  9. Simulations numériques de différentes méthodes d'éléments finis pour les problèmes de contact avec frottementNumerical implementation of different finite element methods for contact problems with friction

    NASA Astrophysics Data System (ADS)

    Baillet, Laurent; Sassi, Taoufik

    2003-11-01

    In this Note, we propose an efficient numerical treatment for solving contact problems with friction between deformable bodies. The discretized normal and tangential constraints at the candidate contact interface are expressed by using either continuous piecewise linear or piecewise constant Lagrange multipliers. Several numerical studies corresponding to this choice are achieved in the PLAST2 code. To cite this article: L. Baillet, T. Sassi, C. R. Mecanique 331 (2003).

  10. SAM Technical Contacts

    EPA Pesticide Factsheets

    These technical contacts are available to help with questions regarding method deviations, modifications, sample problems or interferences, quality control requirements, the use of alternative methods, or the need to address analytes or sample types.

  11. [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.

  12. 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…

  13. 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…

  14. 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…

  15. 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…

  16. 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.

  17. A Synthesis of Language Learning Strategies: Current Issues, Problems and Claims Made in Learner Strategy Research

    ERIC Educational Resources Information Center

    Barjesteh, Hamed; Mukundan, Jayakaran; Vaseghi, Reza

    2014-01-01

    The current paper presented theoretical assumptions behind language learning strategies (LLS) and an overview of methods used to identify learners' strategies, first, and then summarized what have been reported from large number of descriptive studies of strategies by language learners. Moreover, the paper tried to present the variety of…

  18. 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…

  19. [Current problems in coronary artery surgery: new methods of myocardial revascularization and vascular anastomosis].

    PubMed

    Masayoshi, O; Kazuta, S; Hiroyuki, H; Hiroshi, I; Kunio, O; Shozo, M; Kazuo, N

    1985-09-01

    Recently, aortocoronary bypass for the patients with ischemic heart disease has been widely performed and excellent operative results have been obtained in Japan. But, there are some problems in coronary artery surgery for the patients with small coronary artery or multiple stenoses of the coronary arteries. For the purpose to resolve of these problems, operative transluminal angioplasty and onlay patch grafting have been routinely done for severely ill cases, and good patency rate of bypass grafts has been confirmed by postoperative angiography in our clinic. Another problem is alternative surgical treatment for these patients whom A-C bypass could not be done, because of diffuse stenosis of the coronary arteries. As a new method of myocardial revascularization for such cases, arterialization of the coronary venous system (Ao-CS bypass, or Ao-LADV bypass) was experimentally performed. Subsequently, improvements of hemodynamics and blood gas analysis during the bypass were obviously recognized in the latter group. Besides, transmyocardial punctures were created by CO2 Laser (output: 60-90 W, irradiation time: 0.15-0.25 sec) in the ischemic myocardium. Newly created myocardial channels were microscopically studied from the stand points of tissue reaction and patency rate. Subsequently, tinned layers of carbonization and coagulation necrosis were observed in the channels and they disappeared gradually, and long-term patency of the channels could be apparently expected from these findings. On the other hand, vascular anastomosis (side-to-side, end-to-end, and end-to-side) by low energy CO2 Laser was experimentally done in which good healing at the site of anastomosis could be microscopically observed.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Current state and problems of integrated development of mineral resources base in Russia

    NASA Astrophysics Data System (ADS)

    Filimonova, I. V.; Eder, L. V.; Mishenin, M. V.; Mamakhatov, T. M.

    2017-09-01

    The article deals with the issues of integrated development of subsoil resources taking into account the actual problems facing the Russian oil and gas complex. The key factors determining the need for integrated development of subsoil resources have been systematized and investigated. These factors are the change of the hydrocarbon resource base quality, the improvement of the depletion degree of basic (unique and major) oil fields, the increase in the number of small and smallest oil fields discovered and introduced into development, the increased capital intensity and the riskiness of geological exploration, and the territorial location of new subsoil use facilities.

  1. 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.

  2. [Problems of work world and its impact on health. Current financial crisis].

    PubMed

    Tomasina, Fernando

    2012-06-01

    Health and work are complex processes. Besides, they are multiple considering the forms they take. These two processes are linked to each other and they are influenced by each other. According to this, it is possible to establish that work world is extremely complex and heterogeneous. In this world, "old" or traditional risks coexist with "modern risks", derived from the new models of work organization and the incorporation of new technologies. Unemployment, work relationships precariousness and work risks outsourcing are results of neoliberal strategies. Some negative results of health-sickness process derived from transformation in work world and current global economic crisis have been noticed in current work conditions. Finally, the need for reconstructing policies focusing on this situation derived from work world is suggested.

  3. 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

  4. Temperature dependent forward current-voltage characteristics of Ni/Au Schottky contacts on AlGaN/GaN heterostructures described by a two diodes model

    NASA Astrophysics Data System (ADS)

    Greco, Giuseppe; Giannazzo, Filippo; Roccaforte, Fabrizio

    2017-01-01

    This paper reports on the temperature dependence of Ni/Au Schottky contacts on AlGaN/GaN heterostructures. The electrical properties of the Schottky barrier were monitored by means of forward current-voltage (I-V) measurements, while capacitance-voltage measurements were used to determine the properties of the two dimensional electron gas. The forward I-V characteristics of Schottky diodes revealed a strong deviation from the ideal behavior, which could not be explained by a standard thermionic emission model. Thus, the Ni/AlGaN/GaN system has been described by a "two diode model," considering the presence of a second barrier height at the AlGaN/GaN heterojunction. Following this approach, the anomalous I-V curves could be explained and the value of the flat-band barrier height (at zero-electric field) could be correctly determined, thus resulting in good agreement with literature data based on photoemission measurements.

  5. A new wavelet transform to sparsely represent cortical current densities for EEG/MEG inverse problems.

    PubMed

    Liao, Ke; Zhu, Min; Ding, Lei

    2013-08-01

    The present study investigated the use of transform sparseness of cortical current density on human brain surface to improve electroencephalography/magnetoencephalography (EEG/MEG) inverse solutions. Transform sparseness was assessed by evaluating compressibility of cortical current densities in transform domains. To do that, a structure compression method from computer graphics was first adopted to compress cortical surface structure, either regular or irregular, into hierarchical multi-resolution meshes. Then, a new face-based wavelet method based on generated multi-resolution meshes was proposed to compress current density functions defined on cortical surfaces. Twelve cortical surface models were built by three EEG/MEG softwares and their structural compressibility was evaluated and compared by the proposed method. Monte Carlo simulations were implemented to evaluate the performance of the proposed wavelet method in compressing various cortical current density distributions as compared to other two available vertex-based wavelet methods. The present results indicate that the face-based wavelet method can achieve higher transform sparseness than vertex-based wavelet methods. Furthermore, basis functions from the face-based wavelet method have lower coherence against typical EEG and MEG measurement systems than vertex-based wavelet methods. Both high transform sparseness and low coherent measurements suggest that the proposed face-based wavelet method can improve the performance of L1-norm regularized EEG/MEG inverse solutions, which was further demonstrated in simulations and experimental setups using MEG data. Thus, this new transform on complicated cortical structure is promising to significantly advance EEG/MEG inverse source imaging technologies.

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

    PubMed

    Han, Qun-Ying; Liu, Zheng-Wen

    2016-05-21

    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.

  7. [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.

  8. Shock-interface interaction: Current research on the Richtmyer- Meshkov problem

    SciTech Connect

    Rupert, V.

    1991-07-17

    The basis for the study of the evolution of a shocked interface stems from the question of the Rayleigh-Taylor (RT) instability (Taylor 1950). Starting in the late 18th century, the stability of an interface submitted to gravitational forces was investigated for the case in which the density of one of the materials across the interface was negligible compared to the other. Taylor analyzed the case in which the Atwood number (ratio of the difference of the densities to their sum) is less than 1, and the acceleration of the system is constant. He determined that the interface was unstable to small perturbations only if the direction of the acceleration normal to the interface coincides with that of the density gradient. Richtmyer (1960) extended Taylor's analysis to the case of an implusive acceleration. His results implied that the interface would be unstable irrespective of the relative orientation of the velocity impulse and the density gradient. His predictions were verified experimentally by Meshkov (1969), and the Richtmyer-Meshkov (RM) instability became a subject of research in its own right. Experimental, numerical, and theoretical works address this problem. The RM problem has been studied with both the shock-tube and laser experiments. In this paper, only shock-tube work is considered. 48 refs., 6 figs.

  9. [Current issues, problems and prospects of tension-free hernioplasty (review)].

    PubMed

    2014-01-01

    In the present study there are discussed modern methods of the tension free hernioplastics, the complications associated with them and technical difficulties, up-to-date views and the perspectives of the issue development in terms of avoiding infectious complications, positioning of implants and their fixation. Hernia is one of the widespread surgical pathologies as it is found in 4% of the population and its share among the inpatient surgical diseases is about 18-30%. Consequently annually up to 20-21 mln hernioplasties are carried out worldwide. Despite of many years of experience in the field of hernia surgical treatment there still exist many unsolved problems such as safe closure of defects of abdominal cavity wall. Up to 200 methods of hernioplastics, various implantations and application of synthetic materials refer to lack of the optimal surgical strategy. In modern herniology priorities are given to tension free plastics. The merge of the synthetic implants and "tension free hernioplastics" concepts enabled sharp reduction of the side effects list, making it possible to perform successful surgeries in that contingent whose treatment by the method of tissue-plasty was related with high risk of lethality. Large scale introduction of tension free hernioplastics caused intensification of the associated problems such as migration, dissection and shortening of the net.

  10. 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

  11. 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.

  12. 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.

  13. Inducible pluripotent stem cells for the treatment of ischemic stroke: current status and problems.

    PubMed

    Zhu, Yu; Wan, Shu; Zhan, Ren-ya

    2012-01-01

    Despite dramatic advancements in medical and surgical care, effective clinical therapies for ischemic stroke are limited. Stem-cell transplantation has emerged as a potential therapeutic approach for cell replacement in ischemic brain injuries. Inducible pluripotent stem cells (iPSCs) have become an alternative cell source for transplantation. They possess efficient capacities for neural differentiation without ethical and immune-rejection concerns. Substantial function of iPSCs in pre-clinical models of ischemic brain injury has been observed. However, several problems remain regarding the treatment of ischemic stroke with iPSCs: tumorigenicity, poor iPSC derivation methods, and undefined delivery variables. With the development of iPSC research, safer and more effective strategies will be achieved for highly effective and tumor-free cell treatment of ischemic stroke.

  14. Marine pollution from land-based sources: current problems and prospects

    SciTech Connect

    Kwiatkowska, B.

    1984-01-01

    Appropriate legal measures for the prevention and abatement of land-based pollution have only recently been undertaken despite its significant share (approximately 80 percent) in marine pollution. This article surveys solutions contained in regional conventions concluded in that field, and also indicates rules and principles to serve as the basis for states cooperation. Special attention has been given to problems which still give rise to controversies: pollution of the sea through international watercourses, control systems consisting of environmental impact assessment, and the obligation of prior notification and consultation, as well as state responsibility for marine pollution damage. The analysis carried out in this article supports the final conclusion that it would be desirable to consider developing guidelines for the drafting of treaties on the protection of the marine environment against pollution from land-based sources. 43 references.

  15. Stabilization wedges: solving the climate problem for the next 50 years with current technologies.

    PubMed

    Pacala, S; Socolow, R

    2004-08-13

    Humanity already possesses the fundamental scientific, technical, and industrial know-how to solve the carbon and climate problem for the next half-century. A portfolio of technologies now exists to meet the world's energy needs over the next 50 years and limit atmospheric CO2 to a trajectory that avoids a doubling of the preindustrial concentration. Every element in this portfolio has passed beyond the laboratory bench and demonstration project; many are already implemented somewhere at full industrial scale. Although no element is a credible candidate for doing the entire job (or even half the job) by itself, the portfolio as a whole is large enough that not every element has to be used.

  16. 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.

  17. 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.

  18. Denervated muscles in humans: limitations and problems of currently used functional electrical stimulation training protocols.

    PubMed

    Kern, Helmut; Hofer, Christian; Mödlin, Michaela; Forstner, Claudia; Raschka-Högler, Doris; Mayr, Winfried; Stöhr, Hans

    2002-03-01

    Prior clinical work showed that electrical stimulation therapy with exponential current is able to slow down atrophy and maintain the muscle during nonpermanent flaccid paralysis. However, exponential currents are not sufficient for long-term therapy of denervated degenerated muscles (DDMs). We initiated a European research project investigating the rehabilitation strategies in humans, but also studying the underlying basic scientific knowledge of muscle regeneration from satellite cells or myoblast activity in animal experiments. In our prior study, we were able to show that high-intensity stimulation of DDMs is possible. At the beginning of training, only single muscle twitches can be elicited by biphasic pulses with durations of 120-150 ms. Later, tetanic contraction of the muscle with special stimulation parameters (pulse duration of 30-50 ms, stimulation frequency of 16-25 Hz, pulse amplitudes of up to 250 mA) can improve the structural and metabolic state of the DDMs. Because there are no nerve endings for conduction of stimuli, large-size, anatomically shaped electrodes are used. This ensures an even contraction of the whole muscle. Contrary to the current clinical knowledge, we were able to stimulate and train denervated muscle 15-20 years after denervation. The estimated amount of muscle fibers that have to be restored is about 2-4 million fibers in each m. quadriceps. To rebuild such a large number of muscle fibers takes up to 3-4 years. Despite constant stimulation parameters and training protocols, there is a high variation in the developed contraction force and fatigue resistance of the muscle during the first years of functional electrical stimulation.

  19. Vaccines for the prevention of respiratory viral infections: problems and current status.

    PubMed

    Olszewska, Wieslawa; Helson, Rebecca; Openshaw, Peter J M

    2004-06-01

    Acute respiratory virus infections cause the majority of lower respiratory tract illnesses and hospitalisations of infants and the elderly. The emergence of new respiratory viruses and a high probability that influenza will cause further pandemics highlights the necessity for developing better preventative strategies. Although there is a clear and pressing need for vaccines to prevent respiratory syncytial virus, rhinoviruses, coronaviruses, parainfluenza and human metapneumovirus, progress has been extremely slow. This review presents the current status of vaccine development for respiratory viral diseases and outlines novel approaches for the future.

  20. Allergic contact dermatitis: epidemiology, molecular mechanisms, in vitro methods and regulatory aspects. Current knowledge assembled at an international workshop at BfR, Germany.

    PubMed

    Peiser, M; Tralau, T; Heidler, J; Api, A M; Arts, J H E; Basketter, D A; English, J; Diepgen, T L; Fuhlbrigge, R C; Gaspari, A A; Johansen, J D; Karlberg, A T; Kimber, I; Lepoittevin, J P; Liebsch, M; Maibach, H I; Martin, S F; Merk, H F; Platzek, T; Rustemeyer, T; Schnuch, A; Vandebriel, R J; White, I R; Luch, A

    2012-03-01

    Contact allergies are complex diseases, and one of the important challenges for public health and immunology. The German 'Federal Institute for Risk Assessment' hosted an 'International Workshop on Contact Dermatitis'. The scope of the workshop was to discuss new discoveries and developments in the field of contact dermatitis. This included the epidemiology and molecular biology of contact allergy, as well as the development of new in vitro methods. Furthermore, it considered regulatory aspects aiming to reduce exposure to contact sensitisers. An estimated 15-20% of the general population suffers from contact allergy. Workplace exposure, age, sex, use of consumer products and genetic predispositions were identified as the most important risk factors. Research highlights included: advances in understanding of immune responses to contact sensitisers, the importance of autoxidation or enzyme-mediated oxidation for the activation of chemicals, the mechanisms through which hapten-protein conjugates are formed and the development of novel in vitro strategies for the identification of skin-sensitising chemicals. Dendritic cell cultures and structure-activity relationships are being developed to identify potential contact allergens. However, the local lymph node assay (LLNA) presently remains the validated method of choice for hazard identification and characterisation. At the workshop the use of the LLNA for regulatory purposes and for quantitative risk assessment was also discussed.

  1. Telocyte's contacts.

    PubMed

    Faussone-Pellegrini, Maria-Simonetta; Gherghiceanu, Mihaela

    2016-07-01

    Telocytes (TC) are an interstitial cell type located in the connective tissue of many organs of humans and laboratory mammals. By means of homocellular contacts, TC build a scaffold whose meshes integrity and continuity are guaranteed by those contacts having a mechanical function; those contacts acting as sites of intercellular communication allow exchanging information and spreading signals. Heterocellular contacts between TC and a great variety of cell types give origin to mixed networks. TC, by means of all these types of contacts, their interaction with the extracellular matrix and their vicinity to nerve endings, are part of an integrated system playing tissue/organ-specific roles.

  2. Structural, Functional, and Metabolic Brain Markers Differentiate Collision versus Contact and Non-Contact Athletes

    PubMed Central

    Churchill, Nathan W.; Hutchison, Michael G.; Di Battista, Alex P.; Graham, Simon J.; Schweizer, Tom A.

    2017-01-01

    There is growing concern about how participation in contact sports affects the brain. Retrospective evidence suggests that contact sports are associated with long-term negative health outcomes. However, much of the research to date has focused on former athletes with significant health problems. Less is known about the health of current athletes in contact and collision sports who have not reported significant medical issues. In this cross-sectional study, advanced magnetic resonance imaging (MRI) was used to evaluate multiple aspects of brain physiology in three groups of athletes participating in non-contact sports (N = 20), contact sports (N = 22), and collision sports (N = 23). Diffusion tensor imaging was used to assess white matter microstructure based on measures of fractional anisotropy (FA) and mean diffusivity (MD); resting-state functional MRI was used to evaluate global functional connectivity; single-voxel spectroscopy was used to compare ratios of neural metabolites, including N-acetyl aspartate (NAA), creatine (Cr), choline, and myo-inositol. Multivariate analysis revealed structural, functional, and metabolic measures that reliably differentiated between sport groups. The collision group had significantly elevated FA and reduced MD in white matter, compared to both contact and non-contact groups. In contrast, the collision group showed significant reductions in functional connectivity and the NAA/Cr metabolite ratio, relative to only the non-contact group, while the contact group overlapped with both non-contact and collision groups. For brain regions associated with contact sport participation, athletes with a history of concussion also showed greater alterations in FA and functional connectivity, indicating a potential cumulative effect of both contact exposure and concussion history on brain physiology. These findings indicate persistent differences in brain physiology for athletes participating in contact and collision sports, which

  3. Structural, Functional, and Metabolic Brain Markers Differentiate Collision versus Contact and Non-Contact Athletes.

    PubMed

    Churchill, Nathan W; Hutchison, Michael G; Di Battista, Alex P; Graham, Simon J; Schweizer, Tom A

    2017-01-01

    There is growing concern about how participation in contact sports affects the brain. Retrospective evidence suggests that contact sports are associated with long-term negative health outcomes. However, much of the research to date has focused on former athletes with significant health problems. Less is known about the health of current athletes in contact and collision sports who have not reported significant medical issues. In this cross-sectional study, advanced magnetic resonance imaging (MRI) was used to evaluate multiple aspects of brain physiology in three groups of athletes participating in non-contact sports (N = 20), contact sports (N = 22), and collision sports (N = 23). Diffusion tensor imaging was used to assess white matter microstructure based on measures of fractional anisotropy (FA) and mean diffusivity (MD); resting-state functional MRI was used to evaluate global functional connectivity; single-voxel spectroscopy was used to compare ratios of neural metabolites, including N-acetyl aspartate (NAA), creatine (Cr), choline, and myo-inositol. Multivariate analysis revealed structural, functional, and metabolic measures that reliably differentiated between sport groups. The collision group had significantly elevated FA and reduced MD in white matter, compared to both contact and non-contact groups. In contrast, the collision group showed significant reductions in functional connectivity and the NAA/Cr metabolite ratio, relative to only the non-contact group, while the contact group overlapped with both non-contact and collision groups. For brain regions associated with contact sport participation, athletes with a history of concussion also showed greater alterations in FA and functional connectivity, indicating a potential cumulative effect of both contact exposure and concussion history on brain physiology. These findings indicate persistent differences in brain physiology for athletes participating in contact and collision sports, which

  4. Professional communication competences of nurses -- a review of current practice and educational problems.

    PubMed

    Włoszczak-Szubzda, Anna; Jarosz, Mirosław J

    2013-01-01

    A dissonance between high 'technical' professionalism of nurses and a relatively low level of patient satisfaction with received care is a phenomenon observed in many countries. Theoretical concept and review of current published studies. Most reviewed studies show that a low level of patient satisfaction occurs in the case of an inadequate interpersonal communication between nurses and patients. Most studies indicate poor effectiveness of shaping communication competences of nurses based on standard education in the area of general psychology and communication knowledge, because this knowledge does not convert itself 'spontaneously' into communication competences during occupational activity. It is necessary to supplement educational programmes for nurses with practical courses in professional interpersonal communication. International experience exchange concerning the shaping of nurses' communication competences may be limited due to cultural, organizational and systems factors.

  5. [The current problems related to nosocomial infections and antibiotic resistance today].

    PubMed

    Tejkalová, Renata

    2017-01-01

    Nosocomial, also known as hospital acquired infections, are today considered to be an important indicator of the quality of health care in all health establishments. They involve an undesirable complication of the provided health care with a number of negative consequences, such as increased morbidity and mortality, longer time of hospitalization and higher costs. Their incidence at present is also related, among other things, to the broadening, sometimes invasive technical possibilities of diagnosing and therapy. Another issue in Czech hospitals consists in the growing resistance of some bacteria to antibiotics. In practice this means considerably limited possibilities of treatment. The contribution brings the current data about the state of bacterial resistance in Czech hospitals (European project EARS-Net - year 2015).Key words: bacterial resistance - European Antimicrobial Resistance Surveillance Network (EARS-Net) - health care related infections - hospital-acquired infections.

  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. 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

  8. [Current problems and strategies in the management of intra-abdominal infection].

    PubMed

    Ren, Jian-An

    2011-07-01

    The incidence of intra-abdominal infection increases annually. The current management of intra-abdominal infection includes immediate resuscitation, prompt source control and appropriate usage of antibiotics. For patients with septic shock, fluid resuscitation should begin immediately when hypotension is present. Fluid resuscitation should be combined with vasoactive drugs. Damage control surgery promotes the development of ultrasound or CT guided percutaneous abscess drainage and open abdomen therapy. Rational use of anti-infective drugs could prevent prevalence of multiple antibiotics resistant bacteria and pan-resistant bacteria. The gut rehabilitation measures can improve the recovery of gut function and restore of enteral nutrition, and thus prevents bacterial translocation in intra-abdominal infection patients. Monitoring and modulations of immune function may further improve the successful rate of treatment of intra-abdominal infections. Non-thyroidal illness syndrome may develop in the severe intra-abdominal infection patients and should be promptly corrected.

  9. [The problem of the linguistic and scientivic position of psychopathology in the framework of current psychiatry].

    PubMed

    Dieckhöfer, K

    1976-01-01

    An attempt has been made to explain on the one hand the significance of the psychopathological terminology. In contrast to the "dynamic psychiatry", where the language has preponderantly an anticipating, finalizing character with regard to the therapeutical process, it is here being made clear that the cognition of the full existence requires a defined analysis in case of a psychic distrubance. A conceivable aspiration for orderliness thus opens the way to impartial objectiveness. To a special extent the psychiatrist here appears to be obliged to the word itself, particularly within the framework of transcultural psychiatric research, that is, both in regard to philosophical and cultural-historical conditions. The figurative and symbolic character of the language seems to be necessary in psychopathology to make clear the existence of a psychopathological state of mind for lack of another system of definition. On the other hand, it should be shown that also psychopathology - without being subjected to foreign infiltration of a philosophysing medical doctrine - must be embedded in the philosophical way of thinking, if it will not evade an answer to the all important question of a finiteness or infiniteness of man beyond all positive ways of thinking by the fact of the psychophysical problems amid its science and the unique irrationality thereof.

  10. Problems Arising from Current Trends in Propulsion System Design and Guidance Schemes

    NASA Technical Reports Server (NTRS)

    McKay, George H., Jr.

    1966-01-01

    Mission requirements in various NASA programs dictate the necessity for high reliability, continual and chronic increases in payload capability, and precise injection into the prescribed orbit. In some vehicles, concepts employed to meet these criteria in the areas of guidance and propulsion have been found to be somewhat in conflict. For the express purpose of increasing reliability, the primary emphasis in engine and feed design has been placed on simplification including the removal of control systems. In the guidance area considerable attention has been given to the development of methods of implementation which allow complete reshaping of the pitch program if the stage should perform at some level other than predicted. In such a guidance scheme the assumption is made that observed differences in performance levels are constant throughout flight. In the absence of propulsion control systems, however, some oscillations about a mean value representative of the shift can be expected. Analyses showed that this occurrence would severely limit the effectiveness of the Iterative Guidance Mode. The purpose of this paper is to deal with the definition, causes and cures of this problem.

  11. 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.

  12. 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

  13. Parameter estimation in Probabilistic Seismic Hazard Analysis: current problems and some solutions

    NASA Astrophysics Data System (ADS)

    Vermeulen, Petrus

    2017-04-01

    A typical Probabilistic Seismic Hazard Analysis (PSHA) comprises identification of seismic source zones, determination of hazard parameters for these zones, selection of an appropriate ground motion prediction equation (GMPE), and integration over probabilities according the Cornell-McGuire procedure. Determination of hazard parameters often does not receive the attention it deserves, and, therefore, problems therein are often overlooked. Here, many of these problems are identified, and some of them addressed. The parameters that need to be identified are those associated with the frequency-magnitude law, those associated with earthquake recurrence law in time, and the parameters controlling the GMPE. This study is concerned with the frequency-magnitude law and temporal distribution of earthquakes, and not with GMPEs. TheGutenberg-Richter frequency-magnitude law is usually adopted for the frequency-magnitude law, and a Poisson process for earthquake recurrence in time. Accordingly, the parameters that need to be determined are the slope parameter of the Gutenberg-Richter frequency-magnitude law, i.e. the b-value, the maximum value at which the Gutenberg-Richter law applies mmax, and the mean recurrence frequency,λ, of earthquakes. If, instead of the Cornell-McGuire, the "Parametric-Historic procedure" is used, these parameters do not have to be known before the PSHA computations, they are estimated directly during the PSHA computation. The resulting relation for the frequency of ground motion vibration parameters has an analogous functional form to the frequency-magnitude law, which is described by parameters γ (analogous to the b¬-value of the Gutenberg-Richter law) and the maximum possible ground motion amax (analogous to mmax). Originally, the approach was possible to apply only to the simple GMPE, however, recently a method was extended to incorporate more complex forms of GMPE's. With regards to the parameter mmax, there are numerous methods of estimation

  14. Confronting spin flavor solutions of the solar neutrino problem with current and future solar neutrino data

    NASA Astrophysics Data System (ADS)

    Barranco, J.; Miranda, O. G.; Rashba, T. I.; Semikoz, V. B.; Valle, J. W.

    2002-11-01

    A global analysis of spin flavor precession (SFP) solutions to the solar neutrino problem is given, taking into account the impact of the full set of latest solar neutrino data, including the recent SNO data and the 1496-day Super-Kamiokande data. These are characterized by three effective parameters: Δm2SOL≡Δm2, the neutrino mixing angle θSOL≡θ, and the magnetic field parameter μB⊥. For the last we adopt a self-consistent magnetohydrodynamics field profile in the convective zone and identify an optimum B⊥~80 kG strength for μ=10-11μB. We find that no low mass (LOW) quasivacuum or vacuum solutions are present at 3σ. In addition to the standard large mixing angle (LMA) oscillation solution, there are two SFP solutions, in the resonant (RSFP) and nonresonant (NRSFP) regimes. These two SFP solutions have a goodness of fit of 84% (RSFP) and 83% (NRSFP), slightly better than the LMA oscillation solution (78%). We discuss the role of solar antineutrino searches in the fit and present a table of best-fit parameters and χ2min values. Should the KamLAND experiment confirm the LMA solution, the SFP solutions may at best be present at a subleading level, leading to a constraint on μB⊥. In the event the LMA is not the solution realized in nature, then experiments such as Borexino can help in distinguishing the LMA solution from the NRSFP solution and the simplest RSFP solution with no mixing.

  15. Turbulent mixing in stably stratified flows of the environment: The current state of the problem (Review)

    NASA Astrophysics Data System (ADS)

    Vasil'Ev, O. F.; Voropaeva, O. F.; Kurbatskii, A. F.

    2011-06-01

    Specific features of the turbulent transfer of the momentum and heat in stably stratified geophysical flows, as well as possibilities for including them into RANS turbulence models, are analyzed. The momentum (but not heat) transfer by internal gravity waves under conditions of strong stability is, for example, one such feature. Laboratory data and measurements in the atmosphere fix a clear dropping trend of the inverse turbulent Prandtl number with an increasing gradient Richardson number, which must be reproduced by turbulence models. Ignoring this feature can cause a false diffusion of heat under conditions of strong stability and lead, in particular, to noticeable errors in calculations of the temperature in the atmospheric boundary layer. Therefore, models of turbulent transfer must include the effect of the action of buoyancy and internal gravity waves on turbulent flows of the momentum. Such a strategy of modeling the stratified turbulence is presented in the review by a concrete RANS model and original results obtained during the modeling of stratified flows in the environment. Semiempirical turbulence models used for calculations of complex turbulent flows in deep stratified bodies of water are also analyzed. This part of the review is based on the data of investigations within the framework of the large international scientific Comparative Analysis and Rationalization of Second-Moment Turbulence Models (CARTUM) project and other publications of leading specialists. The most economical and effective approach associated with modified two-parameter turbulence models is a real alternative to classical variants of these models. A class of test problems and laboratory and full-scale experiments used by the participants of the CARTUM project for the approbation of numerical models are considered.

  16. 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

  17. Current findings, future trends, and unsolved problems in studies of medicinal mushrooms.

    PubMed

    Wasser, Solomon P

    2011-03-01

    The target of the present review is to draw attention to many critically important unsolved problems in the future development of medicinal mushroom science in the twenty-first century. Special attention is paid to mushroom polysaccharides. Many, if not all, higher Basidiomycetes mushrooms contain biologically active polysaccharides in fruit bodies, cultured mycelium, and cultured broth. The data on mushroom polysaccharides are summarized for approximately 700 species of higher Hetero- and Homobasidiomycetes. The chemical structure of polysaccharides and its connection to antitumor activity, including possible ways of chemical modification, experimental testing and clinical use of antitumor or immunostimulating polysaccharides, and possible mechanisms of their biological action, are discussed. Numerous bioactive polysaccharides or polysaccharide-protein complexes from medicinal mushrooms are described that appear to enhance innate and cell-mediated immune responses and exhibit antitumor activities in animals and humans. Stimulation of host immune defense systems by bioactive polymers from medicinal mushrooms has significant effects on the maturation, differentiation, and proliferation of many kinds of immune cells in the host. Many of these mushroom polymers were reported previously to have immunotherapeutic properties by facilitating growth inhibition and destruction of tumor cells. While the mechanism of their antitumor actions is still not completely understood, stimulation and modulation of key host immune responses by these mushroom polymers appears central. Particularly and most importantly for modern medicine are polysaccharides with antitumor and immunostimulating properties. Several of the mushroom polysaccharide compounds have proceeded through phases I, II, and III clinical trials and are used extensively and successfully in Asia to treat various cancers and other diseases. A total of 126 medicinal functions are thought to be produced by medicinal

  18. 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. © 2011 American Association of Blood Banks.

  19. [Current problems in training of minimally invasive surgery: vision of residents in pediatric surgery].

    PubMed

    Corona, C; Cano, I; Peláez, D; Fuentes, S; Tardáguila, A R

    2013-01-01

    Minimally Invasive Surgery (MIS) is getting more and more important in our specialty. However, the formation of the residents on MIS is, in many cases, irregular. The purpose of this study is to assess the state of training in MIS among the residents of Pediatric Surgery and their potential weaknesses. An electronic survey was distributed among 71 residents of Pediatric Surgery from 17 national hospitals. The response rate was 70.2%.100% of the residents are interested in a broadening of training activities in MIS. The main areas of interest are gastrointestinal (92%) and thoracic (47%) surgery. Only 57% have access to training facilities and less than half of them attend to courses and conferences. 80% believe that they are not given adequate attention from specialized associations. 52% think they should do rotations at referral centers, 86% that courses and seminars should be enhanced, and 44% that the responsibility of the resident in surgery should be increased. The main defects encountered in their training are scarce volume of patients, lack of financial support and overcoming the learning curve of surgeons in their services. Despite the advance of the MIS, resident's training in this discipline still has shortcomings, as expressed in their views. Knowledge of the current state of training should be the starting point for designing a training strategy that ensures adequate skills.

  20. 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

  1. Feline panleukopenia virus: its interesting evolution and current problems in immunoprophylaxis against a serious pathogen.

    PubMed

    Truyen, Uwe; Parrish, Colin R

    2013-07-26

    Vaccination of cats against feline panleukopenia virus (FPV) has been a routine part of feline medicine for the past 40 or more years, and many of the same vaccines that were first developed in the 1960s are still in routine use today. However, there has been significant evolution of the virus in the last 40 years, in particular the emergence of canine parvovirus (CPV) in dogs in the late 1970s, which was a host range variant of the FPV-like virus, and the world-wide spread of the CPV-derived viruses since 1978. FPV and the various antigenic types of CPV have been isolated from cats, raccoons, and many different wild and captive carnivores. The consequences of these changes in the viral populations have not been investigated, and the effectiveness of the current vaccine protocols have not been reported. Here we review the recent findings about the evolution of the viruses in carnivores including cats, and describe a study that looks at the efficiency of vaccination of kittens using the standard protocols, which shows that many cats are not protected by those approaches. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. [Pre-hospital treatment of ophidian accidents: review, update, and current problems].

    PubMed

    Gil-Alarcón, Guillermo; Sánchez-Villegas, María Del Carmen; Hugo Reynoso, Víctor

    2011-01-01

    Mythic, out-dated, ambiguous and sometimes iatrogenic procedures, still remain in pre-hospital and hospital ophidian accident treatment. Errors, omissions and ignorance make ophidian accidents appear more dangerous than they truly are, resulting in a general public contempt toward snakes. Here we present an updated review of current knowledge on pre-hospital and hospital treatment of ophidian bite incidents, including indications, recommendations and logic errors. We describe an appropriate treatment for native Mexican poisonous snakebites using fabotherapics, based on our experience. Adequate initial pre-hospital and hospital management is crucial for a successful outcome of this medical emergency. We describe the state of the art in snake bite research discussing those procedures where research is needed to implement them either by the patient, first responders, paramedics and doctors. We suggest proposals to achieve even more efficient management of fabotherapics based on support networks. Finally, we emphasize prevention as the main subject of venom bite treatment, as it is always more adequate and economic to invest in prevention than to spend on mitigation during emergency and recovery.

  3. 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.

  4. Comparison of Ti/Pd/Ag, Pd/Ti/Pd/Ag and Pd/Ge/Ti/Pd/Ag contacts to n-type GaAs for electronic devices handling high current densities

    NASA Astrophysics Data System (ADS)

    Huo, Pengyun; Galiana, Beatriz; Rey-Stolle, Ignacio

    2017-04-01

    In the quest for metal contacts for electronic devices handling high current densities, we report the results of Pd/Ti/Pd/Ag and Pd/Ge/Ti/Pd/Ag contacts to n-GaAs and compare them to Ti/Pd/Ag and AuGe/Ni/Au. These metal systems have been designed with the goal of producing an electrical contact with (a) low metal-semiconductor specific contact resistance, (b) very high sheet conductance, (c) good bondability, (d) long-term durability and (e) cost-effectiveness. The structure of the contacts consists of an interfacial layer (either Pd or Pd/Ge) intended to produce a low metal-semiconductor specific contact resistance; a diffusion barrier (Ti/Pd) and a thick top layer of Ag to provide the desired high sheet conductance, limited cost and good bondability. The results show that both systems can achieve very low metal resistivity (ρ M ˜ 2 × 10-6 Ω cm), reaching values close to that of pure bulk silver. This fact is attributed to the Ti/Pd bilayer acting as an efficient diffusion barrier, and thus the metal sheet resistance can be controlled by the thickness of the deposited silver layer. Moreover, the use of Pd as interfacial layer produces contacts with moderate specific contact resistance (ρ C ˜ 10-4 Ω cm2) whilst the use of Pd/Ge decreases the specific contact resistance to ρ C ˜ 1.5 × 10-7 Ω cm2, as a result of the formation of a Pd4(GaAs, Ge2) compound at the GaAs interface.

  5. 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

  6. The current status and problems confronted in delivering precision medicine in Japan and Europe.

    PubMed

    Bando, Hideaki

    Precision medicine has been defined as "a predictive, preventive, personalized, and participatory health care service delivery model." Today, developments in next-generation sequencing and information technology have made precision medicine possible, with massive amounts of genetic, "omics," clinical, environmental, and lifestyle data now available. Unfortunately, differences in governmental support and health care regulations have resulted in heterogeneous progress among countries. In Japan, for example, precision cancer screening and treatments are increasingly being promoted, with collaboration among research, governmental, and pharmaceutical agencies taking place in the nationwide SCRUM-Japan cancer genome screening project. The missions of SCRUM-Japan are to deliver the most appropriate therapeutic agents to the most suitable patients, and to play key roles in the development of multiplex diagnostic products and new indications for targeted therapy. Starting in February 2015 and ending in March 2017, the aim is to enroll 4750 patients with cancer (2350 patients with lung cancer and 2400 patients with gastrointestinal tract cancer). Compared with other developed countries, investments in scientific innovation for biomedical and omics research are matched or even surpassed in Europe, but regulatory differences in each countries are a major hurdle to rapid implementation. Although market approval for pharmaceuticals is centralized through the European Medicines Agency, access to health care is heterogeneously regulated at national levels, which undermines the consistency, comparability, and quality of precision medicine for cancer patients in Europe. In this review, we focus on the current progress of precision medicine in Japan and Europe, and clarify the differences in progress and the hurdles faced moving forward. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Current perspective of the HCAP problem: is it CAP or is it HAP?

    PubMed

    Polverino, Eva; Torres, Antoni

    2009-04-01

    microbial composition and MRI risk factors of HCAP is fundamental because no definitive therapeutic indications are currently available.

  8. 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.

  9. Contact dermatitis in printing tradesmen.

    PubMed

    Nethercott, J R; Nosal, R

    1986-05-01

    During a 2-year period in Toronto, Canada, 21 printing tradesmen with contact dermatitis were evaluated. 67% had allergic contact dermatitis; 29% due to ultraviolet-cured ink components. Irritant contact dermatitis accounted for 37% of the cases. The prognosis in printing tradesmen with contact dermatitis is guarded, except for those with allergic contact dermatitis due to UV-cured components, as the tradesmen who were sensitized to other contactants eventually left the trade. Offset lithography was associated with the problem in 18 of the 21 cases. A brief outline is given of the printing processes in common use.

  10. Effectiveness of a training program for police officers who come into contact with people with mental health problems: A pragmatic randomised controlled trial

    PubMed Central

    Fairhurst, Caroline; Booth, Alison; McDaid, Catriona; Moran, Nicola; Parker, Adwoa; Payne, Rebecca; Scott, William J.; Torgerson, David; Webber, Martin; Hewitt, Catherine

    2017-01-01

    Introduction Police officers frequently come into contact with individuals with mental health problems. Specialist training in this area for police officers may improve how they respond to individuals with mental health problems; however, evidence to support this is sparse. This study evaluated the effectiveness of one bespoke mental health training package for frontline police officers relative to routine training. Design Pragmatic, two-armed cluster randomised controlled trial in one police force in England. Police stations in North Yorkshire were randomised with frontline police officers receiving either a bespoke mental health training package or routine training. The primary outcome was the number of incidents which resulted in a police response reported to the North Yorkshire Police control room up to six months after delivery of training. Secondary outcomes included: likelihood of incidents using Section 136 of the Mental Health Act; likelihood of incidents having a mental health tag applied; and number of individuals with a mental health warning marker involved in incidents. The appropriateness of mental health tags applied to a random sample of incidents was checked by an independent mental health professional. Routinely collected data were used. Results Twelve police stations were recruited and randomised (Intervention group n = 6; Control group n = 6), and 249 officers received the bespoke mental health training intervention. At follow-up, a median of 397 incidents were assigned to trial stations in the intervention group, and 498 in the control group. There was no evidence of a difference in the number of incidents with a police response (adjusted incidence rate ratio (IRR) 0.92, 95% CI 0.61 to 1.38, p = 0.69), or in the number of people with mental health warning markers involved in incidents (adjusted IRR 1.39, 95% CI 0.91 to 2.10, p = 0.13) between the intervention and control groups up to six months following the intervention; however, incidents

  11. Effectiveness of a training program for police officers who come into contact with people with mental health problems: A pragmatic randomised controlled trial.

    PubMed

    Scantlebury, Arabella; Fairhurst, Caroline; Booth, Alison; McDaid, Catriona; Moran, Nicola; Parker, Adwoa; Payne, Rebecca; Scott, William J; Torgerson, David; Webber, Martin; Hewitt, Catherine

    2017-01-01

    Police officers frequently come into contact with individuals with mental health problems. Specialist training in this area for police officers may improve how they respond to individuals with mental health problems; however, evidence to support this is sparse. This study evaluated the effectiveness of one bespoke mental health training package for frontline police officers relative to routine training. Pragmatic, two-armed cluster randomised controlled trial in one police force in England. Police stations in North Yorkshire were randomised with frontline police officers receiving either a bespoke mental health training package or routine training. The primary outcome was the number of incidents which resulted in a police response reported to the North Yorkshire Police control room up to six months after delivery of training. Secondary outcomes included: likelihood of incidents using Section 136 of the Mental Health Act; likelihood of incidents having a mental health tag applied; and number of individuals with a mental health warning marker involved in incidents. The appropriateness of mental health tags applied to a random sample of incidents was checked by an independent mental health professional. Routinely collected data were used. Twelve police stations were recruited and randomised (Intervention group n = 6; Control group n = 6), and 249 officers received the bespoke mental health training intervention. At follow-up, a median of 397 incidents were assigned to trial stations in the intervention group, and 498 in the control group. There was no evidence of a difference in the number of incidents with a police response (adjusted incidence rate ratio (IRR) 0.92, 95% CI 0.61 to 1.38, p = 0.69), or in the number of people with mental health warning markers involved in incidents (adjusted IRR 1.39, 95% CI 0.91 to 2.10, p = 0.13) between the intervention and control groups up to six months following the intervention; however, incidents assigned to stations in the

  12. Hydrodynamics of Moving Contact Lines: Macroscopic versus Microscopic.

    PubMed

    Lukyanov, Alex V; Pryer, Tristan

    2017-08-29

    The fluid-mechanics community is currently divided in assessing the boundaries of applicability of the macroscopic approach to fluid mechanical problems. Can the dynamics of nanodroplets be described by the same macroscopic equations as are used for macrodroplets? To the greatest degree, this question should be addressed to the moving-contact-line problem. The problem is naturally multiscale, where even using slip boundary conditions results in spurious numerical solutions and transcendental stagnation regions in modeling in the vicinity of the contact line. In this article, it is demonstrated through mutual comparisons between macroscopic modeling and molecular dynamics simulations that a small, albeit natural, change in the boundary conditions is all that is necessary to completely regularize the problem and eliminate these nonphysical effects. The limits of the macroscopic approach applied to the moving-contact-line problem have been tested and validated on the basis of microscopic first-principles molecular dynamics simulations.

  13. [Eye contact in adult patients with Asperger syndrome].

    PubMed

    Roy, M; Wolfgang, D

    2015-05-01

    It is unclear if individuals with autism spectrum disorders rarely hold direct eye contact because eyes are unimportant for them, or if it is actively avoided. The aim of the current investigation was to gain a better understanding for their views on direct eye contact by exploring adult patients with Asperger syndrome. 63 adult patients with Asperger syndrome (28 females, 35 males, 21 - 62 years old) were explored about using and sensing direct eye contact by means of a standardised questionnaire. 87 % of investigated patients depict direct eye contact as being disagreeable. They describe it as arduous and distracting. Therefore they mostly actively avoid direct eye contact. The here gained knowledge about aversion towards direct eye contact in individuals with autism should lead to a stronger understanding and acceptance of this problem in the non-autistic population. © Georg Thieme Verlag KG Stuttgart · New York.

  14. 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.

  15. Current Problems of Education and Proposals for Improvement in Tai Nationality Schools in Gengma Tai-Wa Nationalities Autonomous County, Yunnan.

    ERIC Educational Resources Information Center

    Zhang, Yuanqing

    1989-01-01

    Identifies current problems of education and proposes means for improving Tai nationality schools. Discusses the language problem, the quality of teachers, budgeting concerns, and effects caused by cultural uniqueness. Offers specific ways to overcome these problems and improve the educational level of Tai nationality students. (KO)

  16. [Current problems arising from not having biosafety level 4 laboratories in Japan--qualitative study of infectious disease experts].

    PubMed

    Yamamoto, Yuko; Horiguchi, Itsuko; Marui, Eiji

    2009-09-01

    No public consensus exists yet on handling Biosafety Level 4 agents and no laboratory is operational at BSL4 in Japan. A discussion that includes neighboring residents and experts should be initiated to communicate risks. In this article, we present the current situation and prioritize problems we presently face. A three-stage Delphi survey was conducted. The subjects were twenty-two persons with extensive experience and knowledge of infectious diseases. Seven projections and issues were made with regard to the problems arising from the lack of an operational BSL4 laboratory. These were tabulated by the KJ method. The top seven projections were scored, such that the top received 7 points and the last received 1 point. A total of 51 projections were obtained for the first part of the survey, 39 for the second, and 29 for the last. The projection with the highest score was that it is impossible to cope with newly emerging infectious diseases. The second was that complete diagnoses are impossible without a BSL4 laboratory. All projections and issues were divided into the following four main groups: issues for researchers and laboratory staff, clinical practice and research on BSL4 agents, domestic and global security, and Japan's international position. We clarified possible problem arising from not having BSL4 laboratories in Japan. The identification of projections by the Delphi survey in this study should be considered as one of many attempts to develop effective risk communication strategies.

  17. 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)

  18. Approximation schemes to dispersion and linear problems for 3D systems on shear current of arbitrary direction and depth dependence

    NASA Astrophysics Data System (ADS)

    Ådnøy Ellingsen, Simen; Li, Yan; Smeltzer, Benjamin K.

    2017-04-01

    We compare different methods of approximating the dispersion relation for waves on top of currents whose direction and magnitude may vary arbitrarily with depth. Two fundamentally different approximation philosophies are in use: analytical approximation schemes, and what we term the N-layer procedure in which the velocity profile is approximated by a continuous, piecewise linear function of depth. The relative virtues of both schemes are reviewed. The N-layer procedure yields the dispersion relation with arbitrary accuracy. We present the details and subtleties of implementing this procedure in practice. We find with a good choice of layer boundaries, 4-5 layers are sufficient for accuracy of about 1%. For inhomogeneous systems with a specified source, implementation is straightforward and most complications are eschewed. Analytical approximation schemes are reviewed, and criteria of applicability are derived for the first time. In particular the much used approximation by Kirby & Chen (1989) (KCA) is compared with a new approximation which we propose. The two give similar predictions when the KCA is applicable, but our new scheme is more robust and can handle several special but realistic cases where the KCA fails. Once the dispersion relation is calculated, 3D linear problems such as initial value problems, or problems with stationary or periodic time dependence can be readily solved.

  19. 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.

  20. 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

  1. Cross-contact chain

    NASA Technical Reports Server (NTRS)

    Lieneweg, U. (Inventor)

    1986-01-01

    A system is provided for use with wafers that include multiple integrated circuits that include two conductive layers in contact at multiple interfaces. Contact chains are formed beside the integrated circuits, each contact chain formed of the same two layers as the circuits, in the form of conductive segments alternating between the upper and lower layers and with the ends of the segments connected in series through interfaces. A current source passes a current through the series-connected segments, by way of a pair of current tabs connected to opposite ends of the series of segments. While the current flows, voltage measurements are taken between each of a plurality of pairs of voltage tabs, the two tabs of each pair connected to opposite ends of an interface that lies along the series-connected segments. A plot of interface conductances on normal probability chart enables prediction of the yield of good integrated circuits from the wafer.

  2. Cross-contact chain

    NASA Technical Reports Server (NTRS)

    Lieneweg, Udo (Inventor)

    1988-01-01

    A system is provided for use with wafers that include multiple integrated circuits that include two conductive layers in contact at multiple interfaces. Contact chains are formed beside the integrated circuits, each contact chain formed of the same two layers as the circuits, in the form of conductive segments alternating between the upper and lower layers and with the ends of the segments connected in series through interfaces. A current source passes a current through the series-connected segments, by way of a pair of current tabs connected to opposite ends of the series of segments. While the current flows, voltage measurements are taken between each of a plurality of pairs of voltage tabs, the two tabs of each pair connected to opposite ends of an interface that lies along the series-connected segments. A plot of interface conductances on a normal probability chart, enables prediction of the yield of good integrated circuits from the wafer.

  3. ASME Heat Transfer Division: Proceedings. Volume 1: Heat transfer in microgravity systems, radiative heat transfer and radiative heat transfer in low-temperature environments, and thermal contact conductance and inverse problems in heat transfer; HTD-Volume 332

    SciTech Connect

    Gopinath, A.; Sadhal, S.S.; Jones, P.D.; Seyed-Yagoobi, J.; Woodbury, K.A.

    1996-12-31

    In the first section on heat transfer in microgravity, the papers cover phase-change phenomena and thermocapillary flows and surface effects. In the second section, several papers cover solution methods for radiative heat transfer while the rest cover heat transfer in low-temperature environments. The last section covers papers containing valuable information for thermal contact conductance of various materials plus papers on inverse problems in heat transfer. Separate abstracts were prepared for most papers in this volume.

  4. 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.

  5. Assessing Predicted Contacts for Building Protein Three-Dimensional Models.

    PubMed

    Adhikari, Badri; Bhattacharya, Debswapna; Cao, Renzhi; Cheng, Jianlin

    2017-01-01

    Recent successes of contact-guided protein structure prediction methods have revived interest in solving the long-standing problem of ab initio protein structure prediction. With homology modeling failing for many protein sequences that do not have templates, contact-guided structure prediction has shown promise, and consequently, contact prediction has gained a lot of interest recently. Although a few dozen contact prediction tools are already currently available as web servers and downloadables, not enough research has been done towards using existing measures like precision and recall to evaluate these contacts with the goal of building three-dimensional models. Moreover, when we do not have a native structure for a set of predicted contacts, the only analysis we can perform is a simple contact map visualization of the predicted contacts. A wider and more rigorous assessment of the predicted contacts is needed, in order to build tertiary structure models. This chapter discusses instructions and protocols for using tools and applying techniques in order to assess predicted contacts for building three-dimensional models.

  6. 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

  7. Efficient solution of 3D electromagnetic eddy-current problems within the finite volume framework of OpenFOAM

    NASA Astrophysics Data System (ADS)

    Beckstein, Pascal; Galindo, Vladimir; Vukčević, Vuko

    2017-09-01

    Eddy-current problems occur in a wide range of industrial and metallurgical applications where conducting material is processed inductively. Motivated by realising coupled multi-physics simulations, we present a new method for the solution of such problems in the finite volume framework of foam-extend, an extended version of the very popular OpenFOAM software. The numerical procedure involves a semi-coupled multi-mesh approach to solve Maxwell's equations for non-magnetic materials by means of the Coulomb gauged magnetic vector potential A and the electric scalar potential ϕ. The concept is further extended on the basis of the impressed and reduced magnetic vector potential and its usage in accordance with Biot-Savart's law to achieve a very efficient overall modelling even for complex three-dimensional geometries. Moreover, we present a special discretisation scheme to account for possible discontinuities in the electrical conductivity. To complement our numerical method, an extensive validation is completing the paper, which provides insight into the behaviour and the potential of our approach.

  8. 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

  9. [Current trends and problems in the measurement of limb loading parameters during transosseous osteosynthesis using external fixation devices].

    PubMed

    Shuts, S A; Dzhafarova, O A; Shuts, B S

    1999-01-01

    The problem in question is whether it is reasonable to equip a conventional limb external fixation apparatus with means for the diagnosis of loading parameters: the forces and displacement of the opposite supporting elements of the apparatus. It is assumed that during distraction osteogenesis it is expedient to apply load to the limb by the load rate only at the initial stage of callus regeneration (the plastic or slightly elastic mechanical state) while the most effective way to do so is to act force at later stages. A number of functions derived from the modified parameters which might aid a physician to choose the optimum limb loading parameters at different stages of treatment were considered by using as example a hypothetical ring-type apparatus equipped with means for continuous measurement of current forces applied to the apparatus and current displacements of opposite ring blocks. Specifications for the measuring system of loading parameters were defined by using an Ilizarov apparatus as an example and why possible rough measurement errors may occur is revealed. The paper shows it necessary to develop methods for calculation of parasitic deformations, i.e. those of the loaded elements of the apparatus for the evaluation of the reciprocal displacement of bone fragments.

  10. 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.

  11. 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

  12. [Current situation of primary prophylaxis with isoniazid (INH) in children who are contacts of patients with bacillary pulmonary tuberculosis in Abidjan (Cote d'Ivoire)].

    PubMed

    Koné, Z; Coulibaly, G; Daix, A T J; Bakayoko, A S; Samaké, K; Kouassi, D P; Domoua, K M S

    2016-12-01

    The National tuberculosis program (NTP) in Ivory Coast recommends that children under 5 years living in a family environment with contagious tuberculosis patients, should receive Prophylactic treatment with INH (PTI), whatever the result of the tuberculin skin test (positive or negative) and their BCG status (vaccinated or not), at a dose of 5mg/kg/day for 6 months. We conducted this study to check the implementation of this recommendation in three support services of tuberculosis in Abidjan, the economic capital. We conducted a multicenter, cross-sectional and descriptive study over 3 years (2011-2013), on consented patients, adolescents and adults aged at least 15 years, with a first episode of infectious pulmonary tuberculosis, in order to look for information on the INH prophylaxis in children under 5 years living under the same roof. We made patients interviews during their visit for bacteriological sputum controls at the second month of TB treatment. Of a total of 412 patients (53% males and 47% females) with a mean age of 34.5 years and with a low level of instruction (66.5%), we noticed 639 children under 5 years living under the same roof with them. Information on the screening of contact children was given to 71% of interviewed patients (291/412). Of the 339 children examined among 639 contacts, 234 (69%) had received only an intradermoreaction (IDR) and PTI was finally administered to 64% of them (217/339). High proportion of contact children under 5 not examined is a major concern for the NTP and a missed opportunity to prevent additional cases of tuberculosis among children. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  13. Jet Fuel-Associated Occupational Contact Dermatitis.

    PubMed

    Contestable, James J

    2017-03-01

    Occupational contact dermatitis is a ubiquitous problem. Sailors onboard U.S. Navy vessels are at high risk given the multitude of potential workplace exposures. Solvents, petrochemicals, and fuels are abundant and can cause irritant or allergic contact dermatitis. Symptoms of contact dermatitis can cause inability to work and, if chronic, may require a change in rating or job. Prevention of this issue requires patient education about the risks and correct personnel protective equipment. Even with preventative strategies in place, exposures and cases of contact dermatitis will occur. Treatment consists of topical steroids and immunomodulators, as well as barrier creams and emollients. The goal of treatment is to fully restore the skin's natural barrier and prevent further exposure. A classic case of jet fuel-associated contact dermatitis is reviewed. A literature review utilizing PubMed, Google Scholar, and Google Search was conducted to elucidate our understanding of this issue, current occupational health guidelines, preventative approaches, and treatments. This case report provides guidance and recommendations for providers who encounter contact dermatitis related to petrochemicals, such as jet fuel. The literature review revealed limited knowledge surrounding in vivo human skin effects of jet fuel, specifically JP-5. Even larger gaps were found in our understanding of, and guidelines for, protective modalities against jet fuel exposure and dermatitis. A case is presented to facilitate recognition of jet fuel contact dermatitis and guidance for treatment and prevention. Given our current limited knowledge and guidelines concerning protective equipment and skin protectants, multiple proposals for future studies are suggested. Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.

  14. How common are long-lasting, intensely itching vaccination granulomas and contact allergy to aluminium induced by currently used pediatric vaccines? A prospective cohort study.

    PubMed

    Bergfors, Elisabet; Hermansson, Göran; Nyström Kronander, Ulla; Falk, Lars; Valter, Lars; Trollfors, Birger

    2014-10-01

    The frequency of long-lasting, intensely itching subcutaneous nodules at the injection site for aluminium (Al)-adsorbed vaccines (vaccination granulomas) was investigated in a prospective cohort study comprising 4,758 children who received either a diphtheria-tetanus-pertussis-polio-Haemophilus influenzae type b vaccine (Infanrix®, Pentavac®) alone or concomitant with a pneumococcal conjugate (Prevenar). Both vaccines were adsorbed to an Al adjuvant. Altogether 38 children (0.83 %) with itching granulomas were identified, epicutaneously tested for Al sensitisation and followed yearly. Contact allergy to Al was verified in 85 %. The median duration of symptoms was 22 months in those hitherto recovered. The frequency of granulomas induced by Infanrix® was >0.66 % and by Prevenar >0.35 %. The risk for granulomas increased from 0.63 to 1.18 % when a second Al-adsorbed vaccine was added to the schedule. Long-lasting itching vaccination granulomas are poorly understood but more frequent than previously known after infant vaccination with commonly used diphtheria-tetanus-pertussis-polio-Haemophilus influenzae type b and pneumococcal conjugate vaccines. The risk increases with the number of vaccines given. Most children with itching granulomas become contact allergic to aluminium. Itching vaccination granulomas are benign but may be troublesome and should be recognised early in primary health care to avoid unnecessary investigations, anxiety and mistrust.

  15. Noise of sliding rough contact

    NASA Astrophysics Data System (ADS)

    Le Bot, Alain

    2017-01-01

    This article is a discussion about the origin of friction noise produced when rubbing solids having rough surfaces. We show that noise emerges from numerous impacts into the contact between antagonist asperities of surfaces. Prediction of sound sources reduces to a statistical problem of contact mechanics. On the other hand, contact is also responsible of dissipation of vibration. This leads to the paradoxical result that the noise may not be proportional to the number of sources.

  16. [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. © Georg Thieme Verlag KG Stuttgart · New York.

  17. [D-cells of the gastroenteropancreatic system: development, structure, function and regeneration (history and current state of the problem)].

    PubMed

    Ivanova, V F; Kostiukevich, S V

    2015-01-01

    The present review summarizes the literature data and the results of authors' own research on the development, structure, function and regeneration of D-endocrinocytes of gastroenteropancreatic (GEP) system. The history of the research of these cells is reviewed and its current state of the problem is discussed. The information on the difference of somatostatin-producing D-endocrinocytes from other types of endocrine cells of GAP system is presented, namely, the prevalence of these cells in all the organs of the digestive system (stomach, small and large intestine, pancreas) and other systems of the body, the peculiarities of their structure and regeneration in various species of vertebrate animals and humans in embryonic development, under conditions of normal functioning and in various types of pathology. On the basis of the data on the early differentiation of D-endocrinocytes and their secretion of hormones during embryonic development, structure, cytophysiology and relationships within the general endocrinocyte population, it is suggested that D-endocrinocytes play an important role in the morpho-functional state of GEP system.

  18. 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

  19. 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, it is…

  20. GaN-based flip-chip LEDs with highly reflective ITO/DBR p-type and via hole-based n-type contacts for enhanced current spreading and light extraction

    NASA Astrophysics Data System (ADS)

    Zhou, Shengjun; Zheng, Chenju; Lv, Jiajiang; Gao, Yilin; Wang, Ruiqing; Liu, Sheng

    2017-07-01

    We demonstrate GaN-based double-layer electrode flip-chip light-emitting diodes (DLE-FCLED) with highly reflective indium-tin oxide (ITO)/distributed bragg reflector (DBR) p-type contact and via hole-based n-type contacts. Transparent thin ITO in combination with TiO2/SiO2 DBR is used for reflective p-type ohmic contact, resulting in a significant reduction in absorption of light by opaque metal electrodes. The finely distributed via hole-based n-type contacts are formed on the n-GaN layer by etching via holes through p-GaN and multiple quantum well (MQW) active layer, leading to reduced lateral current spreading length, and hence alleviated current crowding effect. The forward voltage of the DLE-FCLED is 0.31 V lower than that of the top-emitting LED at 90 mA. The light output power of DLE-FCLED is 15.7% and 80.8% higher than that of top-emitting LED at 90 mA and 300 mA, respectively. Compared to top- emitting LED, the external quantum efficiency (EQE) of DLE-FCLED is enhanced by 15.4% and 132% at 90 mA and 300 mA, respectively. The maximum light output power of the DLE-FCLED obtained at 195.6 A/cm2 is 1.33 times larger than that of the top-emitting LED obtained at 93 A/cm2.

  1. 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

  2. Solving the problem of shock wave attenuation in an obstacle during a contact explosion of a high-energy material charge

    NASA Astrophysics Data System (ADS)

    Kuzin, E. N.; Zagarskih, V. I.; Efanov, V. V.

    2016-12-01

    A problem of estimation of shock wave attenuation in an obstacle under an explosion of a high-energy material (explosive) charge on its surface is considered. An algorithm for its solution is proposed using the analytical and semiempirical dependences generally recognized in explosion physics.

  3. 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.

  4. 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, ...

  5. 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.

  6. Non-contact characterization of hybrid aluminium/carbon-fibre-reinforced plastic sheets using multi-frequency eddy-current sensors

    NASA Astrophysics Data System (ADS)

    Yin, W.; Li, X.; Withers, P. J.; Peyton, A. J.

    2010-10-01

    The characterization of hybrid aluminium/carbon-fibre-reinforced plastic (CFRP) sheets using multi-frequency eddy-current sensors is presented in this paper. Both air-cored circular sensors and highly directional ferrite-cored sensors are designed for bulk conductivity measurements and directionality characterization. An analytical model describing the interaction of the circular sensors with the hybrid planar structure is developed. Finite element (FE) models that take into account the anisotropicity of CFRP have also been proposed. Both models are in good agreement with experimental results. The features of the sensor output signals are analysed and explained. It is proved that an anisotropic model (tensor expression for conductivity) is appropriate for the CFRP materials under investigation. A formula to link the bulk conductivity with the conductivity tensor is proposed and verified. Lift-off effects are also discussed. It is believed that this is amongst the first published reports of using eddy-current techniques for characterizing the hybrid aluminium/CFRP material.

  7. 3D computation of an incipient motion of a sessile drop on a rigid surface with contact angle hysteresis

    NASA Astrophysics Data System (ADS)

    Linder, Nicklas; Criscione, Antonio; Roisman, Ilia V.; Marschall, Holger; Tropea, Cameron

    2015-12-01

    Contact line phenomena govern a large number of multiphase flows. A reliable description of the contact line dynamics is therefore essential for prediction of such flows. Well-known difficulties of computation of the wetting phenomena include the mesh dependence of the results caused by flow singularity near the contact line and accurate estimation of its propagating velocity. The present study deals with the computational problem arising from the discontinuity in the dependence of the dynamic contact angle on the propagation velocity, associated with the contact angle hysteresis. The numerical simulations are performed using the volume of fluid method. The boundary conditions in the neighborhood of the contact line are switched depending on the value of the computed current local contact angle between a propagating contact line and a pinning condition. The method is applied to the simulation of the deformation and incipient motion of a shedding drop. The model is validated by comparison of the numerical predictions with experimental data.

  8. 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.

  9. Contact Dermatitis

    MedlinePlus

    ... skin condition can take a bit of detective work. Dermatologists frequently treat this condition. In fact, this is one of the most ... a rash. Your dermatologist can recommend ways to work and products to use. More than 80% ... and recover without any problems. Image used with ...

  10. Contact Problem on the Interaction of Two Lap Plates, Absolutely Rigid in Tension and Flexible in Bending, with a Thin Circular Sector

    NASA Astrophysics Data System (ADS)

    Sargsyan, A. M.

    2017-03-01

    Using the Fourier method, a solution is constructed for the boundary-value problem of elasticity theory for a circular sector whose radial sides are reinforced by two lap plates absolutely rigid in tension and flexible in bending. On the arc part of its contour, external conditions are given. The stress singularity in the vicinity of top of the circular sector and the behavior of coefficients of the singularity are investigated. It is established that stresses in this vicinity have a singularity of the type r -1+ ɛ ( ɛ > 0; ɛ → 0 at α → π or α → 2 π), whose coefficients, in the general case of loading of the arc part of the sector, differ from zero, which is inadmissible from the viewpoint of the mechanics of brittle fracture. However, an appropriate selection of external conditions on the arc part of sector allows one to equate these coefficients to zero.

  11. GIREP Conference in Israel: Oscillations and Waves and Current Problems in Physics Teaching (Weizmann Institute of Science, Rehovot, Israel, 19-24 August 1979).

    ERIC Educational Resources Information Center

    Mikelskis, Helmut

    1980-01-01

    Discusses oscillations and waves as a new topic for primary and secondary science curricula because of the many developments in the fields of optics and electronics. Outlines current problems in physics instruction under the headings of social aspects, disadvantaged pupils, and developing countries. (GS)

  12. 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.

  13. 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

  14. Contact Lens-related Complications: A Review

    PubMed Central

    Alipour, Fateme; Khaheshi, Saeed; Soleimanzadeh, Mahya; Heidarzadeh, Somayeh; Heydarzadeh, Sepideh

    2017-01-01

    Contact lens-related problems are common and can result in severe sight-threatening complications or contact lens drop out if not addressed properly. We systematically reviewed the most important and the most common contact lens-related complications and their diagnosis, epidemiology, and management according to the literature published in the last 20 years. PMID:28540012

  15. The influence of stabilizers on the production of gold nanoparticles by direct current atmospheric pressure glow microdischarge generated in contact with liquid flowing cathode

    NASA Astrophysics Data System (ADS)

    Dzimitrowicz, Anna; Jamroz, Piotr; Greda, Krzysztof; Nowak, Piotr; Nyk, Marcin; Pohl, Pawel

    2015-04-01

    Gold nanoparticles (Au NPs) were prepared by direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between a miniature argon flow microjet and a flowing liquid cathode. The applied discharge system was operated in a continuous flow liquid mode. The influence of various stabilizers added to the solution of the liquid cathode, i.e., gelatin (GEL), polyvinylpyrrolidone (PVP), or polyvinyl alcohol (PVA), as well as the concentration of the Au precursor (chloroauric acid, HAuCl4) in the solution on the production growth of Au NPs was investigated. Changes in the intensity of the localized surface plasmon resonance (LSPR) band in UV/Vis absorption spectra of solutions treated by dc-μAPGD and their color were observed. The position and the intensity of the LSPR band indicated that relatively small nanoparticles were formed in solutions containing GEL as a capping agent. In these conditions, the maximum of the absorption LSPR band was at 531, 534, and 535 nm, respectively, for 50, 100, and 200 mg L-1 of Au. Additionally, scanning electron microscopy (SEM) and dynamic light scattering (DLS) were used to analyze the structure and the morphology of obtained Au NPs. The shape of Au NPs was spherical and uniform. Their mean size was ca. 27, 73, and 92 nm, while the polydispersity index was 0.296, 0.348, and 0.456 for Au present in the solution of the flowing liquid cathode at a concentration of 50, 100, and 200 mg L-1, respectively. The production rate of synthesized Au NPs depended on the precursor concentration with mean values of 2.9, 3.5, and 5.7 mg h-1, respectively.

  16. 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.

  17. Implications of the current insolubility of the mind-brain problem for the contemporary practice of psychodynamic psychiatry.

    PubMed

    Chessick, Richard D

    2009-01-01

    Abstract Even in this so-called era of the brain, there has been no consensual agreement on understanding the genesis of the mind by the brain, the problem that also baffled Freud, the neurologist at the start of his great discoveries. Especially, there has been no progress in solving what is known as the "hard problem," namely, how neurophysiological processes in the brain can produce conscious experiences, feelings, and intentions that constitute the "qualia," the various aspects of the phenomena of consciousness. Some of the predominant contemporary positions on the mind-brain problem, from Freud's Project for a Scientific Psychology to the present day, will be described and some of the technical vocabulary will be explained. I will conclude from this review that the "mysterian" position or some derivatives of it such as "anomalous monism" or "agnostic materialism" are probably the most plausible, given the present state of our knowledge and capacities. The latter two positions suggest that we simply do not know enough about the physical world of matter at this time but eventually perhaps discoveries about the nature of matter may solve the problem. But as of now, the implication of this impasse is that the introspective data of consciousness are ontologically subjective, pointing to the absolute necessity for our studying this data in its own domain through introspection. The most meticulous and thorough method for this study is psychoanalytic psychiatry, which was specifically devised by Freud for that purpose.

  18. Current Problems of Improving the Environmental Certification and Output Compliance Verification in the Context of Environmental Management in Kazakhstan

    ERIC Educational Resources Information Center

    Zhambaev, Yerzhan S.; Sagieva, Galia K.; Bazarbek, Bakhytzhan Zh.; Akkulov, Rustem T.

    2016-01-01

    The article discusses the issues of improving the activity of subjects of environmental management in accordance with international environmental standards and national environmental legislation. The article deals with the problem of ensuring the implementation of international environmental standards, the introduction of eco-management, and the…

  19. 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.

  20. Current Research on Relationships between Selected Higher Order Processes and the Communication Skills and Problems of Deaf Persons.

    ERIC Educational Resources Information Center

    Metz, Dale Evan; And Others

    1980-01-01

    The paper presents four research projects in process in the Communication Sciences Laboratory at the National Technical Institute for the Deaf. These projects illustrate four broad areas of research on the relationships between higher order information processing systems and the communication skills and problems exhibited by deaf people. (Author)

  1. Articular Contact Mechanics from an Asymptotic Modeling Perspective: A Review

    PubMed Central

    Argatov, Ivan; Mishuris, Gennady

    2016-01-01

    In the present paper, we review the current state-of-the-art in asymptotic modeling of articular contact. Particular attention has been given to the knee joint contact mechanics with a special emphasis on implications drawn from the asymptotic models, including average characteristics for articular cartilage layer. By listing a number of complicating effects such as transverse anisotropy, non-homogeneity, variable thickness, nonlinear deformations, shear loading, and bone deformation, which may be accounted for by asymptotic modeling, some unsolved problems and directions for future research are also discussed. PMID:27847803

  2. Al-based front contacts for HCPV solar cell

    NASA Astrophysics Data System (ADS)

    Huo, Pengyun; Rey-Stolle, Ignacio

    2017-09-01

    One of the key design challenges for high efficiency concentrator solar cells is to minimize the impact of ohmic losses associated with the large current densities that these devices handle. Typically, the most critical component of the series resistance is that of the front contact. On the one hand, in order to minimize its metal-semiconductor specific contact resistance, AuGeNi alloys are frequently used at the interface. On the other hand, to minimize the metal sheet resistance in the grid, thick silver layers are used, sometimes even coated with a gold capping layer. Such configuration results in a contact with good performance, but with elevated cost, and sometimes prone to suffering from degradation problems (electromigration, spiking, …) and deteriorated metal sheet conductance due to the interdiffusion between GaAs and the metals in the contact. In this work, we have explored a low cost high performance alternative based on Pd/Ge/Ti/Pd/Al metal stacks. The thicker top Al layer offers low metal resistivity, low cost, and good bondability; the middle Ti/Pd bilayer works as an efficient two-way diffusion barrier; and the interfacial Pd/Ge layer provides very low specific contact resistance to the GaAs contact layer. The results show that a Pd/Ge/Ti/Pd/Al front contact reduces the series resistance and thus can improve the performance of solar cells at ultrahigh concentration levels.

  3. The centrality of personal relationships in the creation and amelioration of mental health problems: the current interdisciplinary case.

    PubMed

    Pilgrim, David; Rogers, Anne; Bentall, Richard

    2009-03-01

    An interdisciplinary case is made for the centrality of personal relationships in the creation and amelioration of mental health problems. Taking the work of John Bowlby as a starting point, the article summarizes accumulating evidence from the past 50 years about the link between childhood adversity and adult mental health problems. Evidence is also reviewed about contemporary interpersonal impacts on adult mental health from natural social settings and in professional therapy. These empirical summaries are then discussed in the context of dominant trends in professional knowledge about bio-determinism within psychiatry and the emphasis upon models and techniques in professional and political advocates of the psychological therapies. It is concluded that the latter trends are diverting us from policies, which properly concede the importance of relationships for improving the mental health of the population.

  4. [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.

  5. 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…

  6. 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…

  7. Iodine-131 metaiodobenzylguanidine (I-131 MIBG) diagnosis and therapy of pheochromocytoma and paraganglioma: current problems, critical issues and presentation of a sample case.

    PubMed

    Castellani, M R; Aktolun, C; Buzzoni, R; Seregni, E; Chiesa, C; Maccauro, M; Aliberti, G L; Vellani, C; Lorenzoni, A; Bombardieri, E

    2013-06-01

    Iodine-131 metaiodobenzylguanidine (I-131 MIBG) has been used for the diagnosis and treatment of malignant pheochromocytomas (PHEO) and paragangliomas (PGL) since 1980's. Despite increasing amount of experience with iodine-131 (I-131) MIBG therapy, many important questions still exist. In this article, we will discuss the current problems learned from clinical experience in diagnosis and therapy of PHEO/PGL with I-131 MIBG, and present a sample case to emphasize the critical aspects for an optimal treatment strategy.

  8. 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

  9. 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.

  10. 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.

  11. Contact Geometry of Curves

    NASA Astrophysics Data System (ADS)

    Vassiliou, Peter J.

    2009-10-01

    Cartan's method of moving frames is briefly recalled in the context of immersed curves in the homogeneous space of a Lie group G. The contact geometry of curves in low dimensional equi-affine geometry is then made explicit. This delivers the complete set of invariant data which solves the G-equivalence problem via a straightforward procedure, and which is, in some sense a supplement to the equivariant method of Fels and Olver. Next, the contact geometry of curves in general Riemannian manifolds (M,g) is described. For the special case in which the isometries of (M,g) act transitively, it is shown that the contact geometry provides an explicit algorithmic construction of the differential invariants for curves in M. The inputs required for the construction consist only of the metric g and a parametrisation of structure group SO(n); the group action is not required and no integration is involved. To illustrate the algorithm we explicitly construct complete sets of differential invariants for curves in the Poincaré half-space H3 and in a family of constant curvature 3-metrics. It is conjectured that similar results are possible in other Cartan geometries.

  12. Heart beats brain: The problem of detecting alpha waves by neuronal current imaging in joint EEG-MRI experiments.

    PubMed

    Mandelkow, H; Halder, P; Brandeis, D; Soellinger, M; de Zanche, N; Luechinger, R; Boesiger, P

    2007-08-01

    It has been suggested recently that the influence of the neuro-magnetic field should make electrical brain activity directly detectable by MRI. To test this hypothesis, we performed combined EEG-MRI experiments which aim to localize the neuronal current sources of alpha waves (8-12 Hz), one of the most prominent EEG phenomena in humans. A detailed analysis of cross-spectral coherence between simultaneously recorded EEG and MRI time series revealed no sign of alpha waves. Instead the EEG-MRI approach was found to be hampered by artefacts due to cardiac pulsation, which extend into the frequency band of alpha waves. Separate brain displacement mapping experiments confirmed that not only the EEG but also the MRI signal is confounded by harmonics of the cardiac frequency even at 10 Hz and beyond. This well-known ballistocardiogram artefact cannot be avoided or eliminated entirely by available signal processing techniques. Therefore we must conclude that current EEG-MRI methodology based on correlation analysis lacks not only the sensitivity but also the specificity required for the reliable detection of alpha waves.

  13. Contact Lenses for Vision Correction

    MedlinePlus

    ... Ophthalmologist Patient Stories Español Eye Health / Glasses & Contacts Contact Lenses Sections Contact Lenses for Vision Correction Contact ... to Know About Contact Lenses Colored Contact Lenses Contact Lenses for Vision Correction Leer en Español: Lentes ...

  14. 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…

  15. Friction Phenomenon in Contact Stress Problems

    DTIC Science & Technology

    1988-07-01

    specimen. A virtual reference grating created by interference of two coherent beams A and B is superimposed on the specimen grating. The specimen and...where f is the frequency of the virtual reference grating, x is the wavelength of the light employed, a is the angle of incidence (Fig. 3), N is the...orders the test case was run again. This corresponds to a similar order of interpolation error which might occur with a virtual reference grating of 240

  16. 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.…

  17. 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…

  18. [Current status of the problem of malignant lymphoma (on the centenary of the theory of malignant lymphoma)].

    PubMed

    Shtern, R D

    1984-01-01

    Malignant lymphomas (ML) differ from other neoplasms by an extreme variety of the morphological terms used for designation of different variants of these tumours and different terms are used to describe the same neoplasm. This resulted in the simultaneous use in different countries of not less than 6 ML classifications including the WHO histocytological classification (1976), which is not universally accepted. Kiel's classification of non-Hodgkin's ML (1974) is the most popular in the majority of the West and East European countries, in USA there is a similar classification by Lukes and Collins (1975). The "Working formulation of ML for the use in clinics" (USA, 1982) starts to be used, although it is simply a terminological compromise also containing certain faults. The historical review of the evolution of the ML concept is given starting from Th. Billroth' works (1883); the concrete examples are given illustrating the dynamics of the ML terms and evaluation of their nature. The singularity of the developmental steps of this concept is noted, in particular the "reticulosis era" (1923-1973). The dependence of ML estimate upon the existing, in a given period, schemes of hemopoiesis is pointed out. The data on the state of this problem in different countries are presented and the necessity of its joint discussion by pathologists and clinicians in order to work out the identical nomenclature for the designation of the same type of ML is outlined.

  19. Medicinal mushrooms for glycemic control in diabetes mellitus: history, current status, future perspectives, and unsolved problems (review).

    PubMed

    Lo, Hui-Chen; Wasser, Solomon P

    2011-01-01

    Diabetes mellitus (DM) is a chronic metabolic disease characterized by hyperglycemia with defects in insulin secretion and/or insulin resistance. Despite great efforts that have been made in the understanding and management of diabetes, its prevalence continues to grow. Recent discoveries have opened up an exciting opportunity for developing new types of therapeutics from medicinal mushrooms to control DM and its complications. To date, more and more active components including polysaccharides and their protein complexes, dietary fibers, and other compounds extracted from fruiting bodies, cultured mycelium, or cultured broth of medicinal mushrooms have been reported as to having anti-hyperglycemic activity. These compounds exhibit their antidiabetic activity via different mechanisms. This article presents an overview of the multiple aspects of diabetes mellitus and the efficacy and mechanism of medicinal mushrooms for glucose control in diabetes, including the inhibition of glucose absorption, protection of beta-cell damage, increase of insulin release, enhancement of antioxidant defense, attenuation of inflammation, modulation of carbohydrate metabolism pathway, and regulation of insulin-dependent and insulin-independent signaling pathways. However, there is insufficient evidence to draw definitive conclusions about the efficacy of individual medicinal mushrooms for diabetes. In addition, the wide variability, the lack of standards for production, and the lack of testing protocols to assess product quality are still problems in producing medicinal mushroom products. Moreover, well-designed randomized controlled trials with long-term consumption are needed to guarantee the bioactivity and safety of medicinal mushroom products for diabetic patients.

  20. Contact material optimization and contact physics in metal-contact microelectromechanical systems (MEMS) switches

    NASA Astrophysics Data System (ADS)

    Yang, Zhenyin

    Metal-contact MEMS switches hold great promise for implementing agile radio frequency (RF) systems because of their small size, low fabrication cost, low power consumption, wide operational band, excellent isolation and exceptionally low signal insertion loss. Gold is often utilized as a contact material for metal-contact MEMS switches due to its excellent electrical conductivity and corrosion resistance. However contact wear and stiction are the two major failure modes for these switches due to its material softness and high surface adhesion energy. To strengthen the contact material, pure gold was alloyed with other metal elements. We designed and constructed a new micro-contacting test facility that closely mimic the typical MEMS operation and utilized this facility to efficiently evaluate optimized contact materials. Au-Ni binary alloy system as the candidate contact material for MEMS switches was systematically investigated. A correlation between contact material properties (etc. microstructure, micro-hardness, electrical resistivity, topology, surface structures and composition) and micro-contacting performance was established. It was demonstrated nano-scale graded two-phase Au-Ni film could possibly yield an improved device performance. Gold micro-contact degradation mechanisms were also systematically investigated by running the MEMS switching tests under a wide range of test conditions. According to our quantitative failure analysis, field evaporation could be the dominant failure mode for highfield (> critical threshold field) hot switching; transient thermal-assisted wear could be the dominant failure mode for low-field hot switching; on the other hand, pure mechanical wear and steady current heating (1 mA) caused much less contact degradation in cold switching tests. Results from low-force (50 muN/micro-contact), low current (0.1 mA) tests on real MEMS switches indicated that continuous adsorbed films from ambient air could degrade the switch contact