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Sample records for friction factor correlation

  1. Corrosion effects on friction factors

    International Nuclear Information System (INIS)

    Magleby, H.L.; Shaffer, S.J.

    1996-01-01

    This paper presents the results of NRC-sponsored material specimen tests that were performed to determine if corrosion increases the friction factors of sliding surfaces of motor-operated gate valves, which could require higher forces to close and open safety-related valves when subjected to their design basis differential pressures. Friction tests were performed with uncorroded specimens and specimens subjected to accelerated corrosion. Preliminary tests at ambient conditions showed that corrosion increased the friction factors, indicating the need for additional tests duplicating valve operating parameters at hot conditions. The additional tests showed friction factors of corroded specimens were 0.1 to 0.2 higher than for uncorroded specimens, and that the friction factors of the corroded specimens were not very dependent on contact stress or corrosion film thickness. The measured values of friction factors for the three corrosion films tested (simulating three operating times) were in the range of 0.3 to 0.4. The friction factor for even the shortest simulated operating time was essentially the same as the others, indicating that the friction factors appear to reach a plateau and that the plateau is reached quickly

  2. Correlations for heat transfer coefficient and friction factor for turbulent flow of air through square and hexagonal ducts with twisted tape insert

    Science.gov (United States)

    Yadav, Rupesh J.; Kore, Sandeep S.; Joshi, Prathamesh S.

    2017-12-01

    The experimental and numerical Nusselt number and friction factor investigation for turbulent flow through a non-circular duct with twisted-tape inserts have been presented. The non-circular ducts include square, hexagonal duct. The results of non-circular ducts are compared with circular duct. All the ducts have same equivalent diameter. The twist ratios used for the experiment are Y = 3.5, 4.5, 5.5 and 6.5. Experiments were carried out on square duct, hexagonal duct and circular duct. The Reynolds number lied between 10,000 and 1, 05,000. The present study is restricted to the flow of air at Pr = 0.7 only and within a narrow temperature range of 40 to 75 ΟC, within which the compressible nature of air can be neglected. The results reveal that, both Nusselt number and friction factor increases as the side of non-circular duct increases. Maximum Nusselt number and friction factor is obtained in case of circular duct with twisted tape. Further the correlations of Nu and f are given for different non circular duct with twisted tape insert for engineering applications for the turbulent regime. Since the thermal performance factor (η) is observed to be within the range of 0.8 to 1.13 for both circular and noncircular ducts, the overall benefit of using twisted tape in the flow field shall nevertheless be marginal.

  3. Correlations for heat transfer coefficient and friction factor for turbulent flow of air through square and hexagonal ducts with twisted tape insert

    Science.gov (United States)

    Yadav, Rupesh J.; Kore, Sandeep S.; Joshi, Prathamesh S.

    2018-05-01

    The experimental and numerical Nusselt number and friction factor investigation for turbulent flow through a non-circular duct with twisted-tape inserts have been presented. The non-circular ducts include square, hexagonal duct. The results of non-circular ducts are compared with circular duct. All the ducts have same equivalent diameter. The twist ratios used for the experiment are Y = 3.5, 4.5, 5.5 and 6.5. Experiments were carried out on square duct, hexagonal duct and circular duct. The Reynolds number lied between 10,000 and 1, 05,000. The present study is restricted to the flow of air at Pr = 0.7 only and within a narrow temperature range of 40 to 75 ΟC, within which the compressible nature of air can be neglected. The results reveal that, both Nusselt number and friction factor increases as the side of non-circular duct increases. Maximum Nusselt number and friction factor is obtained in case of circular duct with twisted tape. Further the correlations of Nu and f are given for different non circular duct with twisted tape insert for engineering applications for the turbulent regime. Since the thermal performance factor (η) is observed to be within the range of 0.8 to 1.13 for both circular and noncircular ducts, the overall benefit of using twisted tape in the flow field shall nevertheless be marginal.

  4. Analytical prediction of turbulent friction factor for a rod bundle

    International Nuclear Information System (INIS)

    Bae, Jun Ho; Park, Joo Hwan

    2011-01-01

    An analytical calculation has been performed to predict the turbulent friction factor in a rod bundle. For each subchannel constituting a rod bundle, the geometry parameters are analytically derived by integrating the law of the wall over each subchannel with the consideration of a local shear stress distribution. The correlation equations for a local shear stress distribution are supplied from a numerical simulation for each subchannel. The explicit effect of a subchannel shape on the geometry parameter and the friction factor is reported. The friction factor of a corner subchannel converges to a constant value, while the friction factor of a central subchannel steadily increases with a rod distance ratio. The analysis for a rod bundle shows that the friction factor of a rod bundle is largely affected by the characteristics of each subchannel constituting a rod bundle. The present analytic calculations well predict the experimental results from the literature with rod bundles in circular, hexagonal, and square channels.

  5. Milled Die Steel Surface Roughness Correlation with Steel Sheet Friction

    DEFF Research Database (Denmark)

    Berglund, J.; Brown, C.A.; Rosén, B.-G.

    2010-01-01

    This work investigates correlations between the surface topography ofmilled steel dies and friction with steel sheet. Several die surfaces were prepared by milling. Friction was measured in bending under tension testing. Linear regression coefficients (R2) between the friction and texture...

  6. Processing-property correlation in friction stir welds

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, A.P.; Lockwood, W.D.; Seidel, T.U. [South Carolina Univ., Columbia, SC (United States). Dept. of Mechanical Engineering

    2000-07-01

    Friction stir welding (FSW) is a relatively new process for joining of metals. The process was invented in 1992 at The Welding Institute, Cambridge, UK. FSW is particularly well suited to use in highly alloyed aluminum because it is a solid state process; therefore, no undesirable, brittle, low-melting eutectic phases are formed during the welding process. The microstructure of a typical friction stir weld is that of a wrought product. The details of the weld formation mechanism have been the subject of some debate. Previous work on elucidation of flow patterns in friction stir welds indicated that the process may be described as an in-situ extrusion. Material flow in two friction stir welds produced using different welding parameters was visualized using embedded marker materials and the fidelity of the visualization technique was demonstrated. Flow of material in the friction stir welds was observed to depend strongly on the temperature of the weld. In this paper, welding temperature measurements are combined with tensile test data to further promote understanding of the process in 2XXX, 5XXX, 6XXX, and 7XXX series aluminum alloys. Weld parameters (spindle rotation rate and welding speed) and time-temperature histories are correlated with the global and local tensile properties, and microstructure of the resulting welds. (orig.)

  7. Performance evaluation for darcy friction factor formulae using ...

    African Journals Online (AJOL)

    (2008) an overview and performance evaluation of these formulae is presented using statistical methods (model of selection criterion and statistical errors). Darcy Friction factor formulae were obtained from archive. These formulae were used to estimate friction factors in pipes at various Reynolds number and relative ...

  8. Accurate solutions of Colebrook-White's friction factor formulae ...

    African Journals Online (AJOL)

    Estimations of friction factor (Ff) in pipeline systems and fluid transport are essential ingredients in engineering fields and processes. In this paper explicit friction factor formulae (Fff) were proposed and evaluated with an aim of developing error free Fff. General Fff that relate Ff, Reynolds number (Re) and relative roughness ...

  9. Aircraft and ground vehicle friction correlation test results obtained under winter runway conditions during joint FAA/NASA Runway Friction Program

    Science.gov (United States)

    Yager, Thomas J.; Vogler, William A.; Baldasare, Paul

    1988-01-01

    Aircraft and ground vehicle friction data collected during the Joint FAA/NASA Runway Friction Program under winter runway conditions are discussed and test results are summarized. The relationship between the different ground vehicle friction measurements obtained on compacted snow- and ice-covered conditions is defined together with the correlation to aircraft tire friction performance under similar runway conditions.

  10. Friction factor of CP aluminium and aluminium–zinc alloys

    Indian Academy of Sciences (India)

    The Rock- well hardness of all the samples were also measured. 3. Results and discussion. Friction factor, m, of CP aluminium is given in table 1 for various test temperatures. The friction factor, m, was low. (0⋅09–0⋅34) up to 673 K but it reached 0⋅90 at 773 K ex- hibiting sticking behaviour. Figure 5 shows the plot of.

  11. Friction

    Science.gov (United States)

    Matsuo, Yoshihiro; Clarke, Daryl D.; Ozeki, Shinichi

    Friction materials such as disk pads, brake linings, and clutch facings are widely used for automotive applications. Friction materials function during braking due to frictional resistance that transforms kinetic energy into thermal energy. There has been a rudimentary evolution, from materials like leather or wood to asbestos fabric or asbestos fabric saturated with various resins such as asphalt or resin combined with pitch. These efforts were further developed by the use of woven asbestos material saturated by either rubber solution or liquid resin binder and functioned as an internal expanding brake, similar to brake lining system. The role of asbestos continued through the use of chopped asbestos saturated by rubber, but none was entirely successful due to the poor rubber heat resistance required for increased speeds and heavy gearing demands of the automobile industry. The use of phenolic resins as binder for asbestos friction materials provided the necessary thermal resistance and performance characteristics. Thus, the utility of asbestos as the main friction component, for over 100 years, has been significantly reduced in friction materials due to asbestos identity as a carcinogen. Steel and other fibrous components have displaced asbestos in disk pads. Currently, non-asbestos organics are the predominate friction material. Phenolic resins continue to be the preferred binder, and increased amounts are necessary to meet the requirements of highly functional asbestos-free disk pads for the automotive industry. With annual automobile production exceeding 70 million vehicles and additional automobile production occurring in developing countries worldwide and increasing yearly, the amount of phenolic resin for friction material is also increasing (Fig. 14.1). Fig. 14.1 Worldwide commercial vehicle production In recent years, increased fuel efficiency of passenger car is required due to the CO2 emission issue. One of the solutions to improve fuel efficiency is to

  12. Stick-slip and Torsional Friction Factors in Inclined Wellbores

    Directory of Open Access Journals (Sweden)

    Aarsnes Ulf Jakob F.

    2018-01-01

    The model is shown to have a good match with the surface and downhole behavior of two deviated wellbores for depths ranging from 1500 to 3000 meters. In particular, the model replicates the amplitude and period of the oscillations, in both the topside torque and the downhole RPM, as caused by the along-string stick slip. It is further shown that by using the surface behavior of the drill-string during rotational startup, an estimate of the static and dynamic friction factors along the wellbore can be obtained, even during stick-slip oscillations, if axial tension in the drillstring is considered. This presents a possible method to estimate friction factors in the field when off-bottom stick slip is encountered, and points in the direction of avoiding stick slip through the design of an appropriate torsional start-up procedure without the need of an explicit friction test.

  13. accurate solutions of colebrook- white's friction factor formulae

    African Journals Online (AJOL)

    HOD

    modeling of Fff using numerical methods and Microsoft Excel Solver are better tools for estimating Ff in pipeline flow problems. Keywords: Friction factor, MSC; AIC; Reynolds number; Engineering Field; pipe flow, statistical methods. 1. INTRODUCTION. In pipeline systems, various parameters are involved in pipe network ...

  14. A temperature dependent slip factor based thermal model for friction ...

    Indian Academy of Sciences (India)

    This paper proposes a new slip factor based three-dimensional thermal model to predict the temperature distribution during friction stir welding of 304L stainless steel plates. The proposed model employs temperature and radius dependent heat source to study the thermal cycle, temperature distribution, power required, the ...

  15. A temperature dependent slip factor based thermal model for friction

    Indian Academy of Sciences (India)

    This paper proposes a new slip factor based three-dimensional thermal model to predict the temperature distribution during friction stir welding of 304L stainless steel plates. The proposed model employs temperature and radius dependent heat source to study the thermal cycle, temperature distribution, power required, the ...

  16. An equation for the dimensionless friction factor of consolidated ...

    African Journals Online (AJOL)

    An equation that relates the dimensionless friction factor of a porous medium its Reynolds number, during incompressible and compressible fluid flow through the medium is proposed. The equation is a curve fit of a graph drawn from the results of Ohirhian for water (liquid) and that of Akpokene for Nitrogen (gas) flow ...

  17. Explicit presentation of the Colebrook's friction factor equation ...

    African Journals Online (AJOL)

    Two explicit and very accurate equations for calculating the friction factor of pipes over the entire range of relative roughness and Reynold's Number covered by the Colebrook's Equation have been developed. A rectangular array of relative Roughness and Reynold's Number was used to test the accuracy of the new ...

  18. Heat transfer and flow friction correlations for perforated plate matrix heat exchangers

    Science.gov (United States)

    Ratna Raju, L.; Kumar, S. Sunil; Chowdhury, K.; Nandi, T. K.

    2017-02-01

    Perforated plate matrix heat exchangers (MHE) are constructed of high conductivity perforated plates stacked alternately with low conductivity spacers. They are being increasingly used in many cryogenic applications including Claude cycle or Reversed Brayton cycle cryo-refrigerators and liquefiers. Design of high NTU (number of (heat) transfer unit) cryogenic MHEs requires accurate heat transfer coefficient and flow friction factor. Thermo-hydraulic behaviour of perforated plates strongly depends on the geometrical parameters. Existing correlations, however, are mostly expressed as functions of Reynolds number only. This causes, for a given configuration, significant variations in coefficients from one correlation to the other. In this paper we present heat transfer and flow friction correlations as functions of all geometrical and other controlling variables. A FluentTM based numerical model has been developed for heat transfer and pressure drop studies over a stack of alternately arranged perforated plates and spacers. The model is validated with the data from literature. Generalized correlations are obtained through regression analysis over a large number of computed data.

  19. Assessments of fluid friction factors for use in leak rate calculations

    Energy Technology Data Exchange (ETDEWEB)

    Chivers, T.C. [Berkeley Technology Centre, Glos (United Kingdom)

    1997-04-01

    Leak before Break procedures require estimates of leakage, and these in turn need fluid friction to be assessed. In this paper available data on flow rates through idealized and real crack geometries are reviewed in terms of a single friction factor k It is shown that for {lambda} < 1 flow rates can be bounded using correlations in terms of surface R{sub a} values. For {lambda} > 1 the database is less precise, but {lambda} {approx} 4 is an upper bound, hence in this region flow calculations can be assessed using 1 < {lambda} < 4.

  20. Experimental research on friction factor of end faces of contacting mechanical seals

    Science.gov (United States)

    Wei, Long; Gu, Bo-qin; Feng, Xiu; Sun, Jian-jun

    2008-11-01

    The friction of the seal faces is the most important phenomenon in working process of contacting mechanical seals. The friction factor f is a key parameter for expressing the friction regime of the seal faces, the frictional power, the wearing capacity, the friction heat productivity, the temperature distortion of the end face and the temperature of the end face. The relationship between the friction factor f and the friction regime of the end faces of contacting mechanical seals was discussed from a microscopic point of view. The friction factor is usually worked out by the friction torque which is measured in the test. In the computer aided testing device of the mechanical seal system, the experimental investigations on the basic performance of the B104a-70 contacting mechanical seal was carried out. The test results indicate that the bigger the spring pressure of B104a-70 contacting mechanical seal, the bigger the friction factor. When the spring pressure is less, the bigger the rotational speed, the bigger the friction factor. But when the spring pressure is equal to 0.0866 MPa, the friction factor is not almost influenced by the rotational speed. When the rotational speed and spring pressure are less, the medium pressure has a less influence on the friction factor. When the rotational speed or spring pressure is bigger, the bigger the medium pressure, the less the friction factor.

  1. Integrated Data Collection and Analysis Project: Friction Correlation Study

    Science.gov (United States)

    2015-08-01

    one more level and repeat from step 7. 3.4 Material Selection Polyurethane based-binder systems, melt-castable explosive formulations and raw... polyurethane based formulations (natural variation of material) or an interaction between the fundamental function of the apparatus and the mixture...procedures in which the samples are ground and sieved prior to testing. Polyurethane based formulations were cast into strips for friction testing and

  2. Double tube heat exchanger with novel enhancement: Part I - flow development length and adiabatic friction factor

    Energy Technology Data Exchange (ETDEWEB)

    Tiruselvam, R.; Raghavan, Vijay R. [Universiti Teknologi PETRONAS, Faculty of Mechanical Engineering, Tronoh (Malaysia)

    2012-04-15

    The study is conducted to evaluate the flow characteristics in a double tube heat exchanger using two new and versatile enhancement configurations. The novelty is that they are usable in single phase forced convection, evaporation and condensation. Correlations are proposed for flow development length and friction factor for use in predicting fluid pumping power in thermal equipment as well as in subsequent heat transfer characterization of the surface. (orig.)

  3. Correlation between Mechanical Properties with Specific Wear Rate and the Coefficient of Friction of Graphite/Epoxy Composites.

    Science.gov (United States)

    Alajmi, Mahdi; Shalwan, Abdullah

    2015-07-08

    The correlation between the mechanical properties of Fillers/Epoxy composites and their tribological behavior was investigated. Tensile, hardness, wear, and friction tests were conducted for Neat Epoxy (NE), Graphite/Epoxy composites (GE), and Data Palm Fiber/Epoxy with or without Graphite composites (GFE and FE). The correlation was made between the tensile strength, the modulus of elasticity, elongation at the break, and the hardness, as an individual or a combined factor, with the specific wear rate (SWR) and coefficient of friction (COF) of composites. In general, graphite as an additive to polymeric composite has had an eclectic effect on mechanical properties, whereas it has led to a positive effect on tribological properties, whilst date palm fibers (DPFs), as reinforcement for polymeric composite, promoted a mechanical performance with a slight improvement to the tribological performance. Statistically, this study reveals that there is no strong confirmation of any marked correlation between the mechanical and the specific wear rate of filler/Epoxy composites. There is, however, a remarkable correlation between the mechanical properties and the friction coefficient of filler/Epoxy composites.

  4. Correlation between Mechanical Properties with Specific Wear Rate and the Coefficient of Friction of Graphite/Epoxy Composites

    Directory of Open Access Journals (Sweden)

    Mahdi Alajmi

    2015-07-01

    Full Text Available The correlation between the mechanical properties of Fillers/Epoxy composites and their tribological behavior was investigated. Tensile, hardness, wear, and friction tests were conducted for Neat Epoxy (NE, Graphite/Epoxy composites (GE, and Data Palm Fiber/Epoxy with or without Graphite composites (GFE and FE. The correlation was made between the tensile strength, the modulus of elasticity, elongation at the break, and the hardness, as an individual or a combined factor, with the specific wear rate (SWR and coefficient of friction (COF of composites. In general, graphite as an additive to polymeric composite has had an eclectic effect on mechanical properties, whereas it has led to a positive effect on tribological properties, whilst date palm fibers (DPFs, as reinforcement for polymeric composite, promoted a mechanical performance with a slight improvement to the tribological performance. Statistically, this study reveals that there is no strong confirmation of any marked correlation between the mechanical and the specific wear rate of filler/Epoxy composites. There is, however, a remarkable correlation between the mechanical properties and the friction coefficient of filler/Epoxy composites.

  5. Subchannel friction factors for rod bundles: laminar flow predictions and their application to turbulent flows

    International Nuclear Information System (INIS)

    Robinson, D.P.

    1979-02-01

    For the calculation of friction factors the use of correlations validated for smooth circular tubes along with the duct hydraulic diameter is known to be inappropriate for certain non-circular geometries. In order to test the validity and range of application of such correlations to the subchannels of rod bundles a computer programme has been written for the prediction of subchannel laminar velocity distributions and friction coefficients for fully developed flow. The theoretical basis and development of the programme is described along with comparisons between predictions and existing solutions for some simple geometries. Using the computer programme a wide range of calculations have been carried out for flow sections representing edge, corner and internal subchannels of rod bundles with particular emphasis on those of in-line pin bundle geometries. Where comparison can be made the predicted laminar coefficients are in excellent agreement with existing solutions. Although the approach adopted here could be used as the basis of a model for the subchannel axial friction factor, careful account should be taken of enhanced turbulent momentum transfer in situations where the flow is not unidirectional. (UK)

  6. Friction factor in smooth and rough gas pipelines. An experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Sletfjerding, Elling

    1999-01-01

    Flow of high pressure natural gas in pipelines has been studied experimentally. Pipeline flow of natural gas is characterized by high Reynolds numbers due to the low viscosity and relatively high density of pressurized gas. Friction factor correlations for high Reynolds number flow in smooth and rough pipes were developed. To study the effect of wall roughness on pipe flow at high Reynolds numbers 8 test pipes with different wall roughness were fabricated. The wall roughness in 6 of the test pipes was varied by adding glass beads in an epoxy coating applied on the pipe wall. One test pipe was treated with a smooth epoxy coating and one was left untreated. The inner diameter of the test pipes was 150 mm. Measurements of the pressure drop in the pipes were made in a closed flow loop at line pressures of 25, 70, 95 and 120 bar. The Reynolds number of the flow was varied in the range 2-30 million. The wall roughness of the test pipes was measured with a stylus instrument. Correlations between the directly measured wall roughness and the friction factor at fully rough flow conditions were presented. To characterize the wall roughness of the test pipes a parameter combining a measure of the roughness height (R{sub q}) and the texture of the wall roughness was used. Due to the high Reynolds number of the flow, minute irregularities of the pipe wall had significant effect on the friction factor in the pipe. The measured wall roughness of the test pipes was in the range 1.4 < R{sub q} <31 (my)m. The flow experiments in test pipes was compared with data from operating pipelines in the North Sea. The offshore pipelines are coated with the same epoxy coating as used in the test pipes. The friction factor in coated offshore gas pipelines showed smooth behavior when the additional pressure drop due to welds were accounted for. The study of coated gas pipelines showed that the friction factor was significantly lower than predicted by standard correlations.

  7. Stress intensity factor analysis of friction sliding at discontinuity interfaces and junctions

    CSIR Research Space (South Africa)

    Phan, AV

    2003-12-01

    Full Text Available A stress intensity factor (SIF) analysis for two dimensional fractures with frictional contact (crack friction) is presented. This analysis is carried out using the symmetric-Galerkin boundary element method, and a modified quarter-point crack tip...

  8. Subchannel and bundle friction factors and flow split parameters for laminar transition and turbulent longitudinal flows in wire wrap spaced hexagonal arrays

    International Nuclear Information System (INIS)

    Hawley, J.T.; Chiu, C.; Todreas, N.E.; Rohsenow, W.M.

    1980-01-01

    Correlations are presented for subchannel and bundle friction factors and flowsplit parameters for laminar, transition and turbulent longitudinal flows in wire wrap spaced hexagonal arrays. These results are obtained from pressure drop models of flow in individual subchannels. For turbulent flow, an existing pressure drop model for flow in edge subchannels is extended, and the resulting edge subchannel friction factor is identified. Using the expressions for flowsplit parameters and the equal pressure drops assumption, the interior subchannel and bundle friction factors are obtained. For laminar flow, models are developed for pressure drops of individual subchannels. From these models, expressions for the subchannel friction factors are identified and expressions for the flowsplit parameters are derived

  9. Experimental investigation of heat transfer and friction factor in a corrugated plate heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Shive Dayal; Nema, V.K. [Department of Mechanical Engineering, MNNIT, Allahabad-211004 U.P. (India)

    2011-07-01

    Experiments are conducted to determine the heat transfer characteristics for fully developed flow of air and water flowing in alternate corrugated ducts with an inter-wall spacing equal to the corrugation height. The friction factor is found for air channel. The test section was formed by three identical corrugated channels having corrugation angle of 30o with cold air flowing in the middle one and hot water equally divided in the adjacent channels. Sinusoidal wavy arcs connected with tangential flat portions make the said corrugation angle with transverse direction. The Reynolds number based on hydraulic diameter varied from 750 to 3200 for water and from 16900 to 68000 for air by changing the mass flow rates of the two fluids. The Prandtl numbers were approximately constant at 2.55 for water and 0.7 for air. The various correlations are obtained Num=0.247Re0.83 for water, Num=66.686Re0.18 and friction factor f = 0.644 / Re0.18 for air.

  10. Friction factor for water flow through packed beds of spherical and non-spherical particles

    Directory of Open Access Journals (Sweden)

    Kaluđerović-Radoičić Tatjana

    2017-01-01

    Full Text Available The aim of this work was the experimental evaluation of different friction factor correlations for water flow through packed beds of spherical and non-spherical particles at ambient temperature. The experiments were performed by measuring the pressure drop across the bed. Packed beds made of monosized glass spherical particles of seven different diameters were used, as well as beds made of 16 fractions of quartz filtration sand obtained by sieving (polydisperse non-spherical particles. The range of bed voidages was 0.359–0.486, while the range of bed particle Reynolds numbers was from 0.3 to 286 for spherical particles and from 0.1 to 50 for non-spherical particles. The obtained results were compared using a number of available literature correlations. In order to improve the correlation results for spherical particles, a new simple equation was proposed in the form of Ergun’s equation, with modified coefficients. The new correlation had a mean absolute deviation between experimental and calculated values of pressure drop of 9.04%. For non-spherical quartz filtration sand particles the best fit was obtained using Ergun’s equation, with a mean absolute deviation of 10.36%. Surface-volume diameter (dSV necessary for correlating the data for filtration sand particles was calculated based on correlations for dV = f(dm and Ψ = f(dm. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. ON172022

  11. Explicit formulas for the computation of friction factors in turbulent pipe flow

    International Nuclear Information System (INIS)

    Selander, W.N.

    1978-11-01

    For fully developed turbulent flow in smooth or rough circular pipe, the friction factor depends on the Reynolds number and on the roughness parameter through an implicit equation, which must usually be solved by an iterative numerical method. In this report we derive several approximate methods for the explicit evaluation of friction factors, with specific reference to the Colebrook-White equation. The accuracy and convenience of each method is discussed and formulas for practical use are recommended. (author)

  12. A temperature dependent slip factor based thermal model for friction ...

    Indian Academy of Sciences (India)

    alloy using the finite element software ABACUS considering constant frictional heat source. Chao & Tang (2003) simulated a temperature distribution of FSW process using finite element software ABACUS .... Nandan et al (2006) stated that the material flow is significant when the viscosity is less than. 4 MPa-s for the ...

  13. An experimental study of pressure drop and friction factor for laminar and transition opposing mixed convection in entrance region of rectangular duct

    International Nuclear Information System (INIS)

    Chong Daotong; Liu Jiping; Yan Junjie

    2011-01-01

    Research highlights: → Laminar and transition opposing mixed convection in duct was investigated. → Pressure drops in entrance region of rectangular duct were less than 6.0 Pa. → Influences of air flowrate, heat flux and inclination angle were considered. → Friction factors showed different characteristics when Re > 1500 or Re < 1500. → Two correlations of friction factor were fitted with deviations less than 10%. -- Abstract: The laminar and transition opposing mixed convection was experimentally investigated when the air flow was in the entrance region through a rectangular duct. The pressure drops were measured under different air flowrates, convective heat fluxes and inclination angles, with the maximum value less than 6.0 Pa. The friction factors were calculated and analyzed under different Reynolds numbers, Grashof numbers and inclination angles. The results indicated that the pressure drops increased with the mean air velocity, and the friction factors showed different characteristics when the Reynolds numbers were larger or smaller than 1500. Finally, the correlations of friction factors were fitted considering the influences of Reynolds number, Grashof number, inclination angle and length to diameter ratio, which fitted the experimental data with the deviations less than ±10.0%.

  14. Cationic agent contrast-enhanced computed tomography imaging of cartilage correlates with the compressive modulus and coefficient of friction.

    Science.gov (United States)

    Lakin, B A; Grasso, D J; Shah, S S; Stewart, R C; Bansal, P N; Freedman, J D; Grinstaff, M W; Snyder, B D

    2013-01-01

    The aim of this study is to evaluate whether contrast-enhanced computed tomography (CECT) attenuation, using a cationic contrast agent (CA4+), correlates with the equilibrium compressive modulus (E) and coefficient of friction (μ) of ex vivo bovine articular cartilage. Correlations between CECT attenuation and E (Group 1, n = 12) and μ (Group 2, n = 10) were determined using 7 mm diameter bovine osteochondral plugs from the stifle joints of six freshly slaughtered, skeletally mature cows. The equilibrium compressive modulus was measured using a four-step, unconfined, compressive stress-relaxation test, and the coefficients of friction were determined from a torsional friction test. Following mechanical testing, samples were immersed in CA4+, imaged using μCT, rinsed, and analyzed for glycosaminoglycan (GAG) content using the 1,9-dimethylmethylene blue (DMMB) assay. The CECT attenuation was positively correlated with the GAG content of bovine cartilage (R(2) = 0.87, P coefficients of friction: CECT vs μ(static) (R(2) = 0.71, P = 0.002), CECT vs μ(static_equilibrium) (R(2) = 0.79, P coefficient of friction. Copyright © 2012 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

  15. CORROSION AND SURFACE PROTECTION IN MACHINE MATERIALS FRICTION HAVE DIFFERENT SURFACE PAIRS EXPERIMENTAL INVESTIGATION OF FACTORS

    OpenAIRE

    Senai YALCINKAYA

    2017-01-01

    Friction force, normal force, linear change. The normal force varies with the loads on the friction object. In order to determine the friction force and the friction coefficient, the friction object and the friction speed are used. The experimental work was carried out in three stages. In the first stage, the effect of normal force on the friction force was studied. In the second step, the friction force of the friction surface area is influenced. The effect of the change of the s...

  16. Measurement and correlation of frictional pressure drop of refrigerant-based nanofluid flow boiling inside a horizontal smooth tube

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Hao; Ding, Guoliang; Jiang, Weiting; Hu, Haitao [Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240 (China); Gao, Yifeng [International Copper Association Shanghai Office, 381 Huaihaizhong Road, Shanghai 200020 (China)

    2009-11-15

    The objective of this paper is to investigate the effect of nanoparticle on the frictional pressure drop characteristics of refrigerant-based nanofluid flow boiling inside a horizontal smooth tube, and to present a correlation for predicting the frictional pressure drop of refrigerant-based nanofluid. R113 refrigerant and CuO nanoparticle were used for preparing refrigerant-based nanofluid. Experimental conditions include mass fluxes from 100 to 200 kg m{sup -2} s{sup -1}, heat fluxes from 3.08 to 6.16 kW m{sup -2}, inlet vapor qualities from 0.2 to 0.7, and mass fractions of nanoparticles from 0 to 0.5 wt%. The experimental results show that the frictional pressured drop of refrigerant-based nanofluid increases with the increase of the mass fraction of nanoparticles, and the maximum enhancement of frictional pressure drop is 20.8% under above conditions. A frictional pressure drop correlation for refrigerant-based nanofluid is proposed, and the predictions agree with 92% of the experimental data within the deviation of {+-}15%. (author)

  17. THE IMPACT OF WALL ROUGHNESS OF THE UNDERGROUND AIRWAYS ON THE VALUE OF HYDRAULIC FRICTION FACTOR

    Directory of Open Access Journals (Sweden)

    Vladimir Rendulić

    1991-12-01

    Full Text Available The studies of turbulent flows in round pipes resulted in many hydraulic formulas up to these days, which can also serve in projecting to calculate the resistance to the air flow in underground openings. The report discusses the way of establishing the hydraulic friction factor of untimbered underground workings when the value of equivalent roughness is obtained by measuring the ventilation parameters in a similar working of some other mine. A double reticular nomogram has been constructed for the fast determination of friction coefficient from the known roughness of an underground working (the paper is published in Croatian.

  18. Heat transfer and friction correlations for artificially roughened solar air heater duct with discrete W-shaped ribs

    International Nuclear Information System (INIS)

    Kumar, Arvind; Bhagoria, J.L.; Sarviya, R.M.

    2009-01-01

    An experimental investigation has been carried out to study the heat transfer and friction characteristics in solar air heater by using discrete W-shaped roughness on one broad wall of solar air heater with an aspect ratio of 8:1, the roughened wall being heated while the remaining three walls are insulated. The experiment encompassed Reynolds number (Re) range from 3000 to 15,000, relative roughness height (e/D h ) in the range of 0.0168-0.0338, relative roughness pitch (p/e) 10 and the angle of attack (α) in the range of 30-75 deg. The effect of parameters on the heat transfer and friction are compared with the result of smooth duct under similar flow conditions. Correlations for heat transfer and friction have been developed as a function of roughness and flow parameters.

  19. Mercury flow tests (first report). Wall friction factor measurement tests and future tests plan

    International Nuclear Information System (INIS)

    Kaminaga, Masanori; Kinoshita, Hidetaka; Haga, Katsuhiro; Hino, Ryutaro; Sudo, Yukio

    1999-07-01

    In the neutron science project at JAERI, we plan to inject a pulsed proton beam of a maximum power of 5 MW from a high intense proton accelerator into a mercury target in order to produce high energy neutrons of a magnitude of ten times or more than existing facilities. The neutrons produced by the facility will be utilized for advanced field of science such as the life sciences etc. An urgent issue in order to accomplish this project is the establishment of mercury target technology. With this in mind, a mercury experimental loop with the capacity to circulate mercury up to 15 L/min was constructed to perform thermal hydraulic tests, component tests and erosion characteristic tests. A measurement of the wall friction factor was carried out as a first step of the mercury flow tests, while testing the characteristic of components installed in the mercury loop. This report presents an outline of the mercury loop and experimental results of the wall friction factor measurement. From the wall friction factor measurement, it was made clear that the wettability of the mercury was improved with an increase of the loop operation time and at the same time the wall friction factors were increased. The measured wall friction factors were much lower than the values calculated by the Blasius equation at the beginning of the loop operation because of wall slip caused by a non-wetted condition. They agreed well with the values calculated by the Blasius equation within a deviation of 10% when the sum of the operation time increased more than 11 hours. This report also introduces technical problems with a mercury circulation and future tests plan indispensable for the development of the mercury target. (author)

  20. CORROSION AND SURFACE PROTECTION IN MACHINE MATERIALS FRICTION HAVE DIFFERENT SURFACE PAIRS EXPERIMENTAL INVESTIGATION OF FACTORS

    Directory of Open Access Journals (Sweden)

    Senai YALCINKAYA

    2017-05-01

    Full Text Available Friction force, normal force, linear change. The normal force varies with the loads on the friction object. In order to determine the friction force and the friction coefficient, the friction object and the friction speed are used. The experimental work was carried out in three stages. In the first stage, the effect of normal force on the friction force was studied. In the second step, the friction force of the friction surface area is influenced. The effect of the change of the shear rate in step 3 on the friction force was investigated. At the last stage, the experimental study of the effect of the material selection on the friction force was made and it was seen that the aluminum / brass surface pair had the smallest friction coefficient as a result of the opening. The greatest coefficient of friction is found in the pair of glass / felt objects.

  1. Implications of Market Frictions : Serial Correlations in Indexes on the Emerging Stock Markets in Central and Eastern Europe

    Directory of Open Access Journals (Sweden)

    Joanna Olbrys

    2014-01-01

    Full Text Available Implications of market frictions in the context of serial correlations in indexes on the Central and Eastern European (CEE stock markets have been analysed. Market frictions, such as non-trading effects, bid/ask spreads, other transaction costs, etc., may be detected by direct measurement, or by indirect identification. Direct measurement of frictions is difficult as intraday trading data are unavailable in the case of most of the emerging CEE stock markets. Indirect identification may be conducted by detecting some empirical phenomena. One of them is evidence of serial correlations in indexes, the so-called the Fisher effect. We explore the problem of serial correlations in indexes on the eight CEE stock markets using data samples from each CEE market separately, as well as a "common trading window" approach, which is widely applied in the case of databases with multivariate time series. The evidence is that nonsynchronous trading effect II between markets may substantially disrupt the analysis of index returns on a domestic market. Using a synchronized database, one may erroneously conclude that the Fisher effect does not exist, although it is present. (original abstract

  2. Determination of Actual Friction Factors in Metal Forming under Heavy Loaded Regimes Combining Experimental and Numerical Analysis

    Directory of Open Access Journals (Sweden)

    Ana María Camacho

    2016-09-01

    Full Text Available Tribological conditions can change drastically during heavy loaded regimes as experienced in metal forming; this is especially critical when lubrication can only be applied at the early stage of the process because the homogeneous lubricant layer can break along the die-workpiece interface. In these cases, adopting a constant friction factor for the lubricant-surface pair may not be a valid assumption. This paper presents a procedure based on the use of dual friction factor maps to determine friction factors employed in heavy loaded regimes. A finite element (FE simulation is used to obtain the friction factor map for the alloy UNS A96082. Experiments were conducted using four lubricants (aluminum anti-size, MoS2 grease, silicone oil, and copper paste to determine the actual friction curves. The experimental procedure is based on the application of lubricant only at the beginning of the first stage of ring compression, and not at intermediate stages as is usual in typical ring compression tests (RCTs. The results show that for small reductions (rh < 20%, the conventional RCT can be applied because the tribological conditions remain similar. For large reductions (rh > 20%, it is recommended to obtain an average value of the friction factor for every lubricant-surface pair in the range of deformation considered.

  3. Testing of a Stand for Analysis of Drilling Mud Friction Factor

    Directory of Open Access Journals (Sweden)

    Stanisław Stryczek

    2006-10-01

    Full Text Available A concept and realization of a universal laboratory stand for analyzing hydromechanical effects accompanying the drilling mud flow are presented in the paper. Requirements for basic technical subassemblies of the stand are defined. The principles of a flow meter, pressure converters and digital data readers are presented. Then a scheme of a laboratory stand, its principle and procedure are discussed. The process of stand testing through an empirical determination of the Faning friction factor for Newtonian fluids is presented and compared with literature data.

  4. New heat transfer and friction factor design data for perforated plate heat exchangers

    Science.gov (United States)

    Hubbell, Richard H.; Cain, Christina L.

    Perforated plate heat exchangers have been found to have inherently low axial conduction and are therefore excellent candidates for cryogenic applications where an all-metal design is required. A total of three plate cores were tested; two were chemically etched and the other mechanically punched. Hole size, percent open area and plate thickness parameters were varied among the plates. Experimental results were compared to analytical projections and found to differ significantly. The single-blow, transient test technique was used to determine the heat transfer coefficients and the isothermal pressure drop test was used to determine friction factors, as a function of Reynolds number.

  5. Friction and anchorage loading revisited.

    Science.gov (United States)

    Dholakia, Kartik D

    2012-01-01

    Contemporary concepts of sliding mechanics explain that friction is inevitable. To overcome this frictional resistance, excess force is required to retract the tooth along the archwire (ie, individual retraction of canines, en masse retraction of anterior teeth), in addition to the amount of force required for tooth movement. The anterior tooth retraction force, in addition to excess force (to overcome friction), produces reciprocal protraction force on molars, thereby leading to increased anchorage loading. However, this traditional concept was challenged in recent literature, which was based on the finite element model, but did not bear correlation to the clinical scenario. This article will reinforce the fact that clinically, friction increases anchorage loading in all three planes of space, considering the fact that tooth movement is a quasistatic process rather than a purely continuous or static one, and that conventional ways of determining the effects of static or dynamic friction on anchorage load cannot be applied to clinical situations (which consist of anatomical resistance units and a complex muscular force system). The article does not aim to quantify friction and its effect on the amount of anchorage load. Rather, a new perspective regarding the role of various additional factors (which is not explained by contemporary concept) that may influence friction and anchorage loading is provided..

  6. Rotordynamic analysis for stepped-labyrinth gas seals using moody's friction-factor model

    International Nuclear Information System (INIS)

    Ha, Tae Woong

    2001-01-01

    The governing equations are derived for the analysis of a stepped labyrinth gas seal generally used in high performance compressors, gas turbines, and steam turbines. The bulk-flow is assumed for a single cavity control volume set up in a stepped labyrinth cavity and the flow is assumed to be completely turbulent in the circumferential direction. The Moody's wall-friction-factor model is used for the calculation of wall shear stresses in the single cavity control volume. For the reaction force developed by the stepped labyrinth gas seal, linearized zeroth-order and first-order perturbation equations are developed for small motion about a centered position. Integration of the resultant first-order pressure distribution along and around the seal defines the rotordynamic coefficients of the stepped labyrinth gas seal. The resulting leakage and rotordynamic characteristics of the stepped labyrinth gas seal are presented and compared with Scharrer's theoretical analysis using Blasius' wall-friction-factor model. The present analysis shows a good qualitative agreement of leakage characteristics with Scharrer's analysis, but underpredicts by about 20 %. For the rotordynamic coefficients, the present analysis generally yields smaller predicted values compared with Scharrer's analysis

  7. Study of rheology and friction factor of natural food hydrocolloid gels

    Directory of Open Access Journals (Sweden)

    Vojtěch Kumbár

    2017-01-01

    Full Text Available Differences in the rheology and friction factor of natural food hydrocolloid gels were studied in this paper. The practical importance of the knowledge of the rheological parameters is quite evident. The experimental data were carried out using a concentric cylinder rotary viscometer. It was prepared 1% hydrocolloid solutions (hydrogels. Hydrogels of the natural gums extracted from the seeds of the plants and plant tubers have been used - carob gum (from the seeds of Ceratonia siliqua, guar gum (from the seeds of Cyamopsis tetragonoloba and tara gum (from the seeds of Caesalpinia spinosa. Rheological behaviour has non-Newtonian pseudoplastic character and the flow curves were fitted using the Otswald - de Waele (power law model and Herschel - Bulkley model. The hydrogels exhibit shear thinning behaviour. The meaning of the rheological parameters on the friction factors during flow of hydrocolloid gels in the tube has been shown. Information on time dependent behaviour of tested liquids has been also obtained. Time dependent curves were fitted by the Gaussian model. Preliminary results obtained for a constant shear rate showed the thixotropic and time-dependent behaviour of the hydrogels. These parameters can be especially used in much software dealing with a numerical simulation of the flow problems.

  8. Simulation of the Thermal Hydraulic Processes in the Horizontal Steam Generator with the Use of the Different Interfacial Friction Correlations

    International Nuclear Information System (INIS)

    Melikhov, V.; Melikhov, O.; Parfenov, Y.; Nerovnov, A.

    2011-01-01

    The horizontal steam generator (SG) is one of specific features of Russian-type pressurized water reactors (VVERs). The main advantages of horizontal steam generator are connected with low steam loads on evaporation surface, simple separation scheme and high circulation ratio. The complex three-dimensional steam-water flows in the steam generator vessel influence significantly the processes of the steam separation, distribution, and deposition of the soluble and non soluble impurities and determine the efficiency and reliability of the steam generator operation. The 3D code for simulation of the three-dimensional steam-water flows in the steam generator could be effective tool for design and optimization of the horizontal steam generator. The results of the code calculations are determined mainly by the set of the correlations describing interaction of the steam-water mixture with the inner constructions of the SG and interfacial friction. The results obtained by 3D code STEG with the usage of the different interfacial friction correlations are presented and discussed in the paper. These results are compared with the experimental ones obtained at the experimental test facility PGV-1500 constructed for investigation of the processes in the horizontal steam generator

  9. Semi-empirical model for the calculation of flow friction factors in wire-wrapped rod bundles

    International Nuclear Information System (INIS)

    Carajilescov, P.; Fernandez y Fernandez, E.

    1981-08-01

    LMFBR fuel elements consist of wire-wrapped rod bundles, with triangular array, with the fluid flowing parallel to the rods. A semi-empirical model is developed in order to obtain the average bundle friction factor, as well as the friction factor for each subchannel. The model also calculates the flow distribution factors. The results are compared to experimental data for geometrical parameters in the range: P(div)D = 1.063 - 1.417, H(div)D = 4 - 50, and are considered satisfactory. (Author) [pt

  10. Biot Critical Frequency Applied as Common Friction Factor for Chalk with Different Pore Fluids and Temperatures

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling; Fabricius, Ida Lykke

    2010-01-01

    Injection of water into chalk hydrocarbon reservoirs has lead to mechanical yield and failure. Laboratory experiments on chalk samples correspondingly show that the mechanical properties of porous chalk depend on pore fluid and temperature. Water has a significant softening effect on elastic...... and we propose that the fluid effect on mechanical properties of highly porous chalk may be the result of liquid‐solid friction. Applying a different strain or stress rate is influencing the rock strength and needs to be included. The resulting function is shown to relate to the material dependent...... and rate independent b-factor used when describing the time dependent mechanical properties of soft rock or soils. As a consequence it is then possible to further characterize the material constant from the porosity and permeability of the rock as well as from pore fluid density and viscosity which...

  11. Heat-transfer and friction factor design data for all-metal compact heat exchangers

    Science.gov (United States)

    Cain, Christina L.

    1989-03-01

    To improve system life, an effort was undertaken to develop all-metal compact heat exchangers to replace existing heat exchangers which contain organic materials. Eliminating organic materials increases system life because outgassing organics can contaminate the helium working fluid and reduce system life. Perforated plate heat exchangers were found to have inherently low axial conduction and are therefore excellent candidates for cryogenic applications where an all-metal design is required. A total of 11 plate cores were tested; 2 were chemically etched, 1 was mechanically punched, and 8 were manufactured using electron beam drilling. Hole size, percent open area, and plate thickness parameters were varied among the plates. Experimental results were compared to analytical projections and found to differ significantly. The single-blow transient test technique was used to determine the heat transfer coefficients and the isothermal pressure drop test was used to determine friction factors, as a function of Reynolds number.

  12. The evaluation of skin friction using a frictional feel analyzer.

    Science.gov (United States)

    Egawa, Mariko; Oguri, Motoki; Hirao, Tetsuji; Takahashi, Motoji; Miyakawa, Michio

    2002-02-01

    Sensory evaluation is an important factor for cosmetic products. Several devices for the measurement of sensory properties have been developed in recent years. The objective here is to measure skin surface friction using these devices and examine the correlation with other physiological parameters in order to evaluate the potential of physical measurement of tactile sensation. A KES-SE Frictional Analyzer, a commercial device for measurement of surface frictional characteristics, was used in this study. An arm holder was added to this device for measurement on the human forearm. The frictional coefficient (MIU) and its mean deviation (MMD) were used as the parameter to indicate surface friction. The moisture content in the stratum corneum was measured with a Corneometer CM825, the transepidermal water loss with a Tewameter TM210, the viscoelastic properties of the skin with a Cutometer SEM575 and the skin surface pattern by observing the negative replica using silicon rubber. The MIU was not influenced by load; however, it was increased due to water application on the skin. The relationship between MIU and the moisture content in the stratum comeum, between MMD and skin surface pattern and between MMD and viscosity of both normal human forearm skin and SDS (sodium dodecyl sulfate)-induced dry skin were confirmed by statistical analysis in a test on human subjects. There was also a correlation between either MIU or MMD and sensory evaluation in the morning after the application of moisturizing products. Human skin surface friction was measured by using a KES-SE Frictional Analyzer. Judging from the correlation between either MIU or MMD and sensory evaluation, we considered this instrumental analysis to be useful for evaluating the tactile impression of human skin.

  13. Metabolic correlates of temperament factors of personality

    International Nuclear Information System (INIS)

    Park, Hyun Soo; Cho, Sang Soo; Yoon, Eun Jin; Bang, Seong Ae; Kim, Yu Kyeong; Kim, Sang Eun

    2007-01-01

    Gender differences in personality are considered to have biological bases. In an attempt to understand the gender differences of personality on neurobiological bases, we conducted correlation analyses between regional brain glucose metabolism and temperament factors of personality in males and females. Thirty-six healthy right-handed volunteers (18 males, 33.8 ± 17.6 y;18 females, 36.2 ± 20.4 y) underwent FDG PET at resting state. Three temperament factors of personality (novelty seeking (NS), harm avoidance (HA), reward dependence (RD)) were assessed using Cloninger's 240-item Temperament and Character Inventory (TCI) within 10 days of FDG PET scan. Correlation between regional glucose metabolism and each temperament factor was tested using SPM2. In males, a significant negative correlation between NS score and glucose metabolism was observed in the bilateral superior temporal gyri, the hippocampus and the insula, while it was found in the bilateral middle frontal gyri, the right superior temporal gyrus and the left cingulate cortex and the putamen in females. A positive HA correlation was found in the right midbrain and the left cingulate gyrus in males, but in the bilateral basal ganglia in females. A negative RD correlation was observed in the right middle frontal and the left middle temporal gyri in males, while the correlation was found in the bilateral middle frontal gyri and the right basal ganglia and the superior temporal gyrus in females. These data demonstrate different cortical and subcortical metabolic correlates of temperament factors of personality between males and females. These results may help understand biological substrate of gender differences in personality and susceptibility to neuropsychiatric illnesses

  14. Metabolic correlates of temperament factors of personality

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyun Soo; Cho, Sang Soo; Yoon, Eun Jin; Bang, Seong Ae; Kim, Yu Kyeong; Kim, Sang Eun [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2007-08-15

    Gender differences in personality are considered to have biological bases. In an attempt to understand the gender differences of personality on neurobiological bases, we conducted correlation analyses between regional brain glucose metabolism and temperament factors of personality in males and females. Thirty-six healthy right-handed volunteers (18 males, 33.8 {+-} 17.6 y;18 females, 36.2 {+-} 20.4 y) underwent FDG PET at resting state. Three temperament factors of personality (novelty seeking (NS), harm avoidance (HA), reward dependence (RD)) were assessed using Cloninger's 240-item Temperament and Character Inventory (TCI) within 10 days of FDG PET scan. Correlation between regional glucose metabolism and each temperament factor was tested using SPM2. In males, a significant negative correlation between NS score and glucose metabolism was observed in the bilateral superior temporal gyri, the hippocampus and the insula, while it was found in the bilateral middle frontal gyri, the right superior temporal gyrus and the left cingulate cortex and the putamen in females. A positive HA correlation was found in the right midbrain and the left cingulate gyrus in males, but in the bilateral basal ganglia in females. A negative RD correlation was observed in the right middle frontal and the left middle temporal gyri in males, while the correlation was found in the bilateral middle frontal gyri and the right basal ganglia and the superior temporal gyrus in females. These data demonstrate different cortical and subcortical metabolic correlates of temperament factors of personality between males and females. These results may help understand biological substrate of gender differences in personality and susceptibility to neuropsychiatric illnesses.

  15. Proximity friction reexamined

    International Nuclear Information System (INIS)

    Krappe, H.J.

    1989-01-01

    The contribution of inelastic excitations to radial and tangential friction form-factors in heavy-ion collisions is investigated in the frame-work of perturbation theory. The dependence of the form factors on the essential geometrical and level-density parameters of the scattering system is exhibited in a rather closed form. The conditions for the existence of time-local friction coefficients are discussed. Results are compared to form factors from other models, in particular the transfer-related proximity friction. For the radial friction coefficient the inelastic excitation mechanism seems to be the dominant contribution in peripheral collisions. (orig.)

  16. Diminishing friction of joint surfaces as initiating factor for destabilising permafrost rocks?

    Science.gov (United States)

    Funk, Daniel; Krautblatter, Michael

    2010-05-01

    Degrading alpine permafrost due to changing climate conditions causes instabilities in steep rock slopes. Due to a lack in process understanding, the hazard is still difficult to asses in terms of its timing, location, magnitude and frequency. Current research is focused on ice within joints which is considered to be the key-factor. Monitoring of permafrost-induced rock failure comprises monitoring of temperature and moisture in rock-joints. The effect of low temperatures on the strength of intact rock and its mechanical relevance for shear strength has not been considered yet. But this effect is signifcant since compressive and tensile strength is reduced by up to 50% and more when rock thaws (Mellor, 1973). We hypotheisze, that the thawing of permafrost in rocks reduces the shear strength of joints by facilitating the shearing/damaging of asperities due to the drop of the compressive/tensile strength of rock. We think, that decreasing surface friction, a neglected factor in stability analysis, is crucial for the onset of destabilisation of permafrost rocks. A potential rock slide within the permafrost zone in the Wetterstein Mountains (Zugspitze, Germany) is the basis for the data we use for the empirical joint model of Barton (1973) to estimate the peak shear strength of the shear plane. Parameters are the JRC (joint roughness coefficient), the JCS (joint compressive strength) and the residual friction angle (φr). The surface roughness is measured in the field with a profile gauge to create 2D-profiles of joint surfaces. Samples of rock were taken to the laboratory to measure compressive strength using a high-impact Schmidt-Hammer under air-dry, saturated and frozen conditions on weathered and unweathered surfaces. Plugs where cut out of the rock and sand blasted for shear tests under frozen and unfrozen conditions. Peak shear strength of frozen and unfrozen rocks will be calculated using Barton's model. First results show a mean decrease of compressive

  17. Study on heat transfer and friction factor characteristics of γ-Al2O3/water through circular tube with twisted tape inserts with different thicknesses

    International Nuclear Information System (INIS)

    Esmaeilzadeh, E.; Almohammadi, H.; Nokhosteen, A.; Motezaker, A.; Omrani, A.N.

    2014-01-01

    An experimental study was carried out to investigate heat transfer and friction factor characteristics of γ-Al 2 O 3 /water nano-fluid through circular tube with twisted tape inserts with various thicknesses at constant heat flux. In this work, γ-Al 2 O 3 /water nano-fluids with two volume concentrations of 0.5% and 1% were used as the working fluid. The twist ratio of twisted tape remained constant at 3.21, while the thicknesses were changed through three values of 0.5 mm, 1 mm and 2 mm. The experiments were performed in laminar flow regime from 150 to 1600 Reynolds numbers. Results indicated that twisted tape inserts enhanced the average convective heat transfer coefficient, and also more the thickness of twisted tape is more the enhancement of convective heat transfer coefficient is. Also, the highest enhancement was achieved at maximum volume concentration. Results showed that nano-fluids have better heat transfer performance when utilized with thicker twisted tapes. At the same time, the increase in twisted tape thickness leads to an increase in friction factor. In the end, the combined results of these two phenomena result in enhanced convective heat transfer coefficient and thermal performance. Finally, two new correlations were offered for Nusselt number and thermal performance based on our experimental observation. (authors)

  18. Numerical investigation of heat transfer and friction factor characteristics in a circular tube fitted with V-cut twisted tape inserts.

    Science.gov (United States)

    Salman, Sami D; Kadhum, Abdul Amir H; Takriff, Mohd S; Mohamad, Abu Bakar

    2013-01-01

    Numerical investigation of the heat transfer and friction factor characteristics of a circular fitted with V-cut twisted tape (VCT) insert with twist ratio (y = 2.93) and different cut depths (w = 0.5, 1, and 1.5 cm) were studied for laminar flow using CFD package (FLUENT-6.3.26). The data obtained from plain tube were verified with the literature correlation to ensure the validation of simulation results. Classical twisted tape (CTT) with different twist ratios (y = 2.93, 3.91, 4.89) were also studied for comparison. The results show that the enhancement of heat transfer rate induced by the classical and V-cut twisted tape inserts increases with the Reynolds number and decreases with twist ratio. The results also revealed that the V-cut twisted tape with twist ratio y = 2.93 and cut depth w = 0.5 cm offered higher heat transfer rate with significant increases in friction factor than other tapes. In addition the results of V-cut twist tape compared with experimental and simulated data of right-left helical tape inserts (RLT), it is found that the V-cut twist tape offered better thermal contact between the surface and the fluid which ultimately leads to a high heat transfer coefficient. Consequently, 107% of maximum heat transfer was obtained by using this configuration.

  19. Determining the friction factors for underground colliery bord and pillar workings

    CSIR Research Space (South Africa)

    Meyer, CF

    1998-05-01

    Full Text Available This project was mainly proposed to make available, to the coal mining industry a set of default friction values that could be used with more confidence in network simulation programs, during the project use was made of both underground...

  20. EXPERIMENTAL STUDY ON HEAT TRANSFER COEFFICIENT AND FRICTION FACTOR OF Al2O3 NANOFLUID IN A PACKED BED COLUMN

    Directory of Open Access Journals (Sweden)

    G. Srinivasa Rao

    2011-12-01

    Full Text Available The forced convection heat transfer coefficient and friction factor are determined for the flow of water and nanofluid in a vertical packed bed column. The analysis is undertaken in the laminar and transition Reynolds number range. The column is filled with spherical glass beads as the bed material. The heat transfer coefficients with Al2O3 nanofluid increased by 12% to 15% with the increase of volume concentration from 0.02% to 0.5% compared with water. The experimental values of axial temperature are in good agreement with the NTU-ε method proposed by Schumann’s model.

  1. An Evaluation of Global and Local Tensile Properties of Friction-Stir Welded DP980 Dual-Phase Steel Joints Using a Digital Image Correlation Method.

    Science.gov (United States)

    Lee, Hyoungwook; Kim, Cheolhee; Song, Jung Han

    2015-12-04

    The effect of the microstructure heterogeneity on the tensile plastic deformation characteristic of friction-stir-welded (FSW) dual-phase (DP) steel was investigated for the potential applications on the lightweight design of vehicles. Friction-stir-welded specimens with a butt joint configuration were prepared, and quasi-static tensile tests were conducted, to evaluate the tensile properties of DP980 dual-phase steels. The friction-stir welding led to the formation of martensite and a significant hardness rise in the stir zone (SZ), but the presence of a soft zone in the heat-affected zone (HAZ) was caused by tempering of the pre-existing martensite. Owing to the appearance of severe soft zone, DP980 FSW joint showed almost 93% joint efficiency with the view-point of ultimate tensile strength and relatively low ductility than the base metal (BM). The local tensile deformation characteristic of the FSW joints was also examined using the digital image correlation (DIC) methodology by mapping the global and local strain distribution, and was subsequently analyzed by mechanics calculation. It is found that the tensile deformation of the FSW joints is highly heterogeneous, leading to a significant decrease in global ductility. The HAZ of the joints is the weakest region where the strain localizes early, and this localization extends until fracture with a strain near 30%, while the strain in the SZ and BM is only 1% and 4%, respectively. Local constitutive properties in different heterogeneous regions through the friction-stir-welded joint was also briefly evaluated by assuming iso-stress conditions. The local stress-strain curves of individual weld zones provide a clear indication of the heterogeneity of the local mechanical properties.

  2. Factors correlated with volleyball spike velocity.

    Science.gov (United States)

    Forthomme, Bénédicte; Croisier, Jean-Louis; Ciccarone, Guido; Crielaard, Jean-Michel; Cloes, Marc

    2005-10-01

    Spike effectiveness represents a determining element in volleyball. To compete at a high level, the player must, in particular, produce a spike characterized by a high ball velocity. Some muscular and physical features could influence ball velocity during the volleyball spike. Descriptive laboratory study. A total of 19 male volleyball players from the 2 highest Belgian national divisions underwent an isokinetic assessment of the dominant shoulder and elbow. Ball velocity performance (radar gun) during a spike test, morphological feature, and jump capacity (ergo jump) of the player were measured. We tested the relationship between the isokinetic parameters or physical features and field performances represented by spike velocity. We also compared first-division and second-division player data. Spike velocity correlated significantly with strength performance of the dominant shoulder (internal rotators) and of the dominant elbow (flexors and extensors) in the concentric mode. Negative correlations were established with the concentric external rotator on internal rotator ratio at 400 deg/s and with the mixed ratio (external rotator at 60 deg/s in the eccentric mode on internal rotator at 240 deg/s in the concentric mode). Positive correlations appeared with both the volleyball players' jump capacity and body mass index. First-division players differed from second-division players by higher ball velocity and increased jump capacity. Some specific strength and physical characteristics correlated significantly with spike performance in high-level volleyball practice. Our results could provide useful information for training management and propose some reflections on injury prevention.

  3. Macroeconomic Factors and the Correlation of Stock and Bond Returns

    OpenAIRE

    Lingfeng Li

    2003-01-01

    This paper examines the correlation between stock and bond returns. It first documents that the major trends in stock-bond correlation for G7 countries follow a similar reverting pattern in the past forty years. Next, an asset pricing model is employed to show that the correlation of stock and bond returns can be explained by their common exposure to macroeconomic factors. The link between the stock-bond correlation and macroeconomic factors is examined using three successively more realistic...

  4. KINEMATICS FRICTION PAIR FOR EXAMPLE NEEDLE BEARINGS

    OpenAIRE

    Jerzy NACHIMOWICZ; Robert KORBUT

    2014-01-01

    The present study concerns certain phenomena that take place in the needle roller bearing. The friction that generates the anti-torque of a friction pair is the major factor that influences the needle bearing’s wear. In the needle bearing there occur two predominant types of friction: the rolling friction and the sliding friction, and both are subject to examination. The study presents recordings and analysis of the movements of all needle bearing’s rolling elements. The examination was carri...

  5. Earthquake friction

    Science.gov (United States)

    Mulargia, Francesco; Bizzarri, Andrea

    2016-12-01

    Laboratory friction slip experiments on rocks provide firm evidence that the static friction coefficient μ has values ∼0.7. This would imply large amounts of heat produced by seismically active faults, but no heat flow anomaly is observed, and mineralogic evidence of frictional heating is virtually absent. This stands for lower μ values ∼0.2, as also required by the observed orientation of faults with respect to the maximum compressive stress. We show that accounting for the thermal and mechanical energy balance of the system removes this inconsistence, implying a multi-stage strain release process. The first stage consists of a small and slow aseismic slip at high friction on pre-existent stress concentrators within the fault volume but angled with the main fault as Riedel cracks. This introduces a second stage dominated by frictional temperature increase inducing local pressurization of pore fluids around the slip patches, which is in turn followed by a third stage in which thermal diffusion extends the frictionally heated zones making them coalesce into a connected pressurized region oriented as the fault plane. Then, the system enters a state of equivalent low static friction in which it can undergo the fast elastic radiation slip prescribed by dislocation earthquake models.

  6. Topological complexity of frictional interfaces: friction networks

    Directory of Open Access Journals (Sweden)

    H. O. Ghaffari

    2012-03-01

    Full Text Available Through research conducted in this study, a network approach to the correlation patterns of void spaces in rough fractures (crack type II was developed. We characterized friction networks with several networks characteristics. The correlation among network properties with the fracture permeability is the result of friction networks. The revealed hubs in the complex aperture networks confirmed the importance of highly correlated groups to conduct the highlighted features of the dynamical aperture field. We found that there is a universal power law between the nodes' degree and motifs frequency (for triangles it reads T(kkβ (β ≈ 2 ± 0.3. The investigation of localization effects on eigenvectors shows a remarkable difference in parallel and perpendicular aperture patches. Furthermore, we estimate the rate of stored energy in asperities so that we found that the rate of radiated energy is higher in parallel friction networks than it is in transverse directions. The final part of our research highlights 4 point sub-graph distribution and its correlation with fluid flow. For shear rupture, we observed a similar trend in sub-graph distribution, resulting from parallel and transversal aperture profiles (a superfamily phenomenon.

  7. External models of frictional interaction dynamics

    Science.gov (United States)

    Tyurin, A. E.; Ismailov, G. M.; Ikonnikova, K. V.; Sarkisov, Y. S.

    2017-10-01

    This investigation suggests a method used to determine the evolution of metallic wear and friction by sliding. The friction of steel moving over brass was taken as an example. The problem of external dynamics friction is investigated through the definition of the dynamic characteristics such as damping factor and natural frequency. Some certain automatic control methods were applied for sliding friction contact, including parametric identification, ARX simulation and Newton’s dynamic equation. The suggested approach allows using amplitude-frequency characteristics to assess the dynamic factors (coefficients) under friction interaction. The research findings indicate that the proposed method allows monitoring the evolution of metallic wear and friction.

  8. Anticipating the friction coefficient of friction materials used in automobiles by means of machine learning without using a test instrument

    OpenAIRE

    TİMUR, Mustafa; AYDIN, Fatih

    2013-01-01

    The most important factor for designs in which friction materials are used is the coefficient of friction. The coefficient of friction has been determined taking such variants as velocity, temperature, and pressure into account, which arise from various factors in friction materials, and by analyzing the effects of these variants on friction materials. Many test instruments have been produced in order to determine the coefficient of friction. In this article, a study about the use ...

  9. Correlation of microstructure and mechanical properties in friction stir welded 2198-T8 Al–Li alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Chong, E-mail: chonggao@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Zhu, Zhixiong, E-mail: zz056@uowmail.edu.au [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Han, Jian; Li, Huijun [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2015-07-15

    In this study, the 1.8 mm thick cold-rolled sheets of 2198-T8 Al–Li alloy were manufactured by friction stir welding (FSW) at a rotation rate of 800 rpm and a travel speed of 300 mm/min. The microstructure and mechanical properties of different regions of the produced joint were evaluated by means of optical microscopy (OM), transmission electron microscopy (TEM), hardness testing and tensile testing. Results show that the original “pancake” grains became coarser in the heat affected zone (HAZ), transformed into equiaxed grains in the stir shoulder zone (SsZ) and stir pin zone (SpZ), and formed mixed grains with both “pancake” and equiaxed shapes in the thermo-mechanical affected zone (TMAZ). The hardness distribution in the cross-section of the FSW joint exhibited a “basin” shape. When approaching the weld centre, the hardness gradually decreased compared to the base metal (BM). The BM exhibited the highest strength due to the presence of fine T1 phase. In the HAZ, the strength decreased as T1 phase was partially dissolved. In the SsZ and SpZ, in spite of strength contribution from grain refinement, the strength further decreased as T1 phase was fully dissolved. The minimum strength in the TMAZ was related to the reduced amount of T1 phase and the presence of transition layer with sharp gradient of grain size. - Highlights: • FSW joint of 2198-T8 alloy was successfully produced. • Microstructure and precipitate evolution in FSW joint were evaluated. • Hardness and strength in different regions of FSW joint were tested. • Strengthening mechanisms in different regions of FSW joint were discussed.

  10. Correlates of Bio-Psychosocial Factors on Perceived Body Image ...

    African Journals Online (AJOL)

    Correlates of Bio-Psychosocial Factors on Perceived Body Image amongst Adolescents: Implications for Preventive Health Education. ... The questionnaire contained measures of demographics, self-esteem, self-efficacy, food habit index, exercise, weight. Data was analyzed using correlation analysis. The results indicated ...

  11. Dental Implant Stability Analysis and Investigating the Influence of Efective Factors on Bone-Implant Contact Applying Frictional Model of Contact

    Directory of Open Access Journals (Sweden)

    Atefi E

    2011-12-01

    Full Text Available Background and Aims: Relative displacement of the implant with respect to bone and quality of bone-implant contact play critical roles in the dental implant stability. The goal of this study was to investigate the dental implant stability using non-linear finite elements method. Therefore, bone-implant relative displacement due to applied force to the implant was calculated, and then an appropriate factor for defining quality of bone-implant contact was presented.Materials and Methods: In order to develop a three dimensional model and compare the results with clinical studies, computed tomography (CT scan data of a rabbit tibia was considered as a base. The model was exported to ABAQUS 6.9-1 to be analyzed using nonlinear finite elements method. Dynamic analysis was done on the model using the proper boundary condition and dynamic loads.Results: Force-displacement curves in bone-implant interface were nonlinear. Friction coefficient, which is a criterion for implant stability and relative displacement, approximately became doubled as the vertical contact force was halved. However, the friction coefficient decreased with reduction of coulomb frictional coefficient.Conclusion: Friction coefficient, which is calculated upon force-displacement curves, could be considered as a criterion to evaluate the dental implant stability. Decrease of the vertical contact force and also using rough surfaces improved the quality of bone-implant contact and stability of dental implant.

  12. Argo packing friction research update

    International Nuclear Information System (INIS)

    VanTassell, D.M.

    1994-01-01

    This paper focuses on the issue of valve packing friction and its affect on the operability of motor- and air-operated valves (MOVs and AOVs). At this time, most nuclear power plants are required to perform postmaintenance testing following a packing adjustment or replacement. In many cases, the friction generated by the packing does not impact the operability window of a valve. However, to date there has not been a concerted effort to substantiate this claim. To quantify the effects of packing friction, it has become necessary to develop a formula to predict the friction effects accurately. This formula provides a much more accurate method of predicting packing friction than previously used factors based strictly on stem diameter. Over the past 5 years, Argo Packing Company has been developing and testing improved graphite packing systems at research facilities, such as AECL Chalk River and Wyle Laboratories. Much of this testing has centered around reducing and predicting friction that is related to packing. In addition, diagnostic testing for Generic Letter 89-10 MOVs and AOVs has created a significant data base. In July 1992 Argo asked several utilities to provide running load data that could be used to quantify packing friction repeatability and predictability. This technical paper provides the basis to predict packing friction, which will improve calculations for thrust requirements for Generic Leter 89-10 and future AOV programs. In addition, having an accurate packing friction formula will improve packing performance when low running loads are identified that would indicate insufficient sealing force

  13. Correlation between Spectral Index and Doppler Factor for a ...

    Indian Academy of Sciences (India)

    Abstract. Relativistic beaming effect is important for blazars. In a very recent work, γ-ray Doppler factors were calculated for a sample of Fermi blazars (Fan et al. 2013). In this work, we investigated the correlation between the Doppler factor and the effective spectral index, αOX, and found an anticorrelation between them.

  14. Caregiver’s feeding styles questionnaire - new factors and correlates

    Science.gov (United States)

    Study objectives were to conduct exploratory factor analysis (EFA) of Caregiver’s Feeding Styles Questionnaire (CFSQ) and evaluate correlations between factors and maternal feeding practices, attitudes, and perceptions. Mothers (N = 144) were 43% minority race/ethnicity, 24% full-time employed, 54% ...

  15. Biot Critical Frequency Applied as Common Friction Factor for Chalk with Different Pore Fluids and Temperatures

    DEFF Research Database (Denmark)

    Andreassen, Katrine Alling; Fabricius, Ida Lykke

    2010-01-01

    Injection of water into chalk hydrocarbon reservoirs has lead to mechanical yield and failure. Laboratory experiments on chalk samples correspondingly show that the mechanical properties of porous chalk depend on pore fluid and temperature. Water has a significant softening effect on elastic...... and rate independent b-factor used when describing the time dependent mechanical properties of soft rock or soils. As a consequence it is then possible to further characterize the material constant from the porosity and permeability of the rock as well as from pore fluid density and viscosity which...

  16. Interfacial friction factors for air-water co-current stratified flow in inclined channels

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Ki Yong; No, Hee Cheon [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1997-12-31

    The interfacial shear stress is experimentally investigated for co-current air-water stratified flow in inclined rectangular channels having a length of 1854mm, width of 120 mm and height of 40mm at almost atmospheric pressure. Experiments are carried out in several inclinations from 0 deg up to 10 deg. The local film thickness and the wave height are measured at three locations, i.e., L/H = 8,23, and 40. According to the inclination angle, the experimental data are categorized into two groups; nearly horizontal data group (0 deg {<=} {theta} {<=} 0.7 deg), and inclined channel data group (0.7 deg {<=} {theta} {<=} 10 deg ). Experimental observations for nearly horizontal data group show that the flow is not fully developed due to the water level gradient and the hydraulic jump within the channel. For the inclined channel data group, a dimensionless wave height, {Delta}h/h, is empirically correlated in terms of Re{sub G} and h/H. A modified root-mean-square wave height is proposed to consider the effects of the interfacial and wave propagation velocities. It is found that an equivalent roughness has a linear relationship with the modified root-mean-square wave height and its relationship is independent of the inclination. 10 refs., 6 figs., 1 tab. (Author)

  17. Intelligent Flow Friction Estimation

    Directory of Open Access Journals (Sweden)

    Dejan Brkić

    2016-01-01

    Full Text Available Nowadays, the Colebrook equation is used as a mostly accepted relation for the calculation of fluid flow friction factor. However, the Colebrook equation is implicit with respect to the friction factor (λ. In the present study, a noniterative approach using Artificial Neural Network (ANN was developed to calculate the friction factor. To configure the ANN model, the input parameters of the Reynolds Number (Re and the relative roughness of pipe (ε/D were transformed to logarithmic scales. The 90,000 sets of data were fed to the ANN model involving three layers: input, hidden, and output layers with, 2, 50, and 1 neurons, respectively. This configuration was capable of predicting the values of friction factor in the Colebrook equation for any given values of the Reynolds number (Re and the relative roughness (ε/D ranging between 5000 and 108 and between 10−7 and 0.1, respectively. The proposed ANN demonstrates the relative error up to 0.07% which had the high accuracy compared with the vast majority of the precise explicit approximations of the Colebrook equation.

  18. Tactile friction of topical formulations.

    Science.gov (United States)

    Skedung, L; Buraczewska-Norin, I; Dawood, N; Rutland, M W; Ringstad, L

    2016-02-01

    The tactile perception is essential for all types of topical formulations (cosmetic, pharmaceutical, medical device) and the possibility to predict the sensorial response by using instrumental methods instead of sensory testing would save time and cost at an early stage product development. Here, we report on an instrumental evaluation method using tactile friction measurements to estimate perceptual attributes of topical formulations. Friction was measured between an index finger and an artificial skin substrate after application of formulations using a force sensor. Both model formulations of liquid crystalline phase structures with significantly different tactile properties, as well as commercial pharmaceutical moisturizing creams being more tactile-similar, were investigated. Friction coefficients were calculated as the ratio of the friction force to the applied load. The structures of the model formulations and phase transitions as a result of water evaporation were identified using optical microscopy. The friction device could distinguish friction coefficients between the phase structures, as well as the commercial creams after spreading and absorption into the substrate. In addition, phase transitions resulting in alterations in the feel of the formulations could be detected. A correlation was established between skin hydration and friction coefficient, where hydrated skin gave rise to higher friction. Also a link between skin smoothening and finger friction was established for the commercial moisturizing creams, although further investigations are needed to analyse this and correlations with other sensorial attributes in more detail. The present investigation shows that tactile friction measurements have potential as an alternative or complement in the evaluation of perception of topical formulations. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Partial structure factors and orientational correlations in liquid HI

    International Nuclear Information System (INIS)

    Andreani, C.; Nardone, M.; Ricci, F.P.

    1993-01-01

    The three atomic partial structure factors of orthobaric liquid HI at 253 K derived from neutron diffraction experiments are presented. The analysis of these structure factors and of the corresponding pair distribution functions indicates that the molecular center of mass distribution function is essentially that of a monoatomic Lennard-Jones fluid and that the anisotropic part of the intermolecular potential is able to build up orientational correlations between molecular axes without however giving rise to well defined correlations between the intermolecular axis and the molecular axis. These findings are consistent with an anisotropic part of the intermolecular potential due essentially to electric multipoles. (authors). 4 figs., 4 refs

  20. Correlation between Spectral Index and Doppler Factor for a ...

    Indian Academy of Sciences (India)

    2013). The correlation between Doppler factor and the spectral index can be discussed using a bigger sample. The relativistic beaming effects are also discussed in this proceedings (Li et al. 2014; Wu et al. 2014; Nie et al. 2014). The effective spectral index αOX is anticorre- lated with the viewing angle, and claimed to be ...

  1. Gender factor as a correlate of students\\' performance on creativity ...

    African Journals Online (AJOL)

    Gender factor as a correlate of students\\' performance on creativity and intellegence tests in Oyo State secondary schools. J O Oyundoyin, R A Olatoye. Abstract. No Abstract. African Journal for the psychological studies of social issues Vol. 10 (1&2) 2007: pp. 251-262. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT

  2. Demographic Factors as Correlates of Health – Seeking Behaviour ...

    African Journals Online (AJOL)

    This study was designed to investigate whether demographic factors could be taken as correlates of health-seeking behaviour of the people of Oyo State, Nigeria. Descriptive research design of survey type was adopted for this study. Sample size of one thousand, one hundred and fifty-two respondents were used.

  3. The Challenges of Socio-Psychological Factors as Correlates of ...

    African Journals Online (AJOL)

    This study investigated adolescent students' cigarette smoking behaviour as correlates of the challenges socio-psychological factors in Cross River State. Snowball sampling technique was used to select 200 participants across the state who were male and female. Their ages ranged between 14 and 19 years with a mean ...

  4. Studies of linear correlation factor of dielectric polarization and ...

    Indian Academy of Sciences (India)

    observed. The dipolar excess free energy of mixing in a given solvent is of the order primary amide > secondary amide > tertiary amide. Keywords. Dielectric constants; amides; Kirkwood–Frohlich correlation factor; Eyring's significant structure theory; dipolar excess free energies. PACS Nos 42.25.Ja; 61.20.Ne; 61.25.Em. 1.

  5. Correlation Between Tumor Necrosis Factor Alpha and Proteinuria ...

    African Journals Online (AJOL)

    Serum tumor necrosis factor-α (TNF-α), urine TNF-α and C-reactive protein (CRP) levels were measured in all subjects. Correlations between these inflammatory parameters and degree of proteinuria, duration of diabetes and degree of glycemic control were examined. Results: Levels of the three inflammatory parameters ...

  6. Prediction of friction coefficients for gases

    Science.gov (United States)

    Taylor, M. F.

    1969-01-01

    Empirical relations are used for correlating laminar and turbulent friction coefficients for gases, with large variations in the physical properties, flowing through smooth tubes. These relations have been used to correlate friction coefficients for hydrogen, helium, nitrogen, carbon dioxide and air.

  7. Investigation on frictional pressure drop of steam-water two-phase flow in an internally ribbed tube

    International Nuclear Information System (INIS)

    Li Yongxing; Chen Tingkuan; Li Huixiong

    2005-01-01

    Within the range of pressures from 9 to 22 MPa, mass velocities from G 600 to 1200 kg/(m 2 ·s), and heat fluxes from x 0 to 1.0, experiments had performed to investigate the frictional pressure drop of the steam-water two-phase flow in a six-head internally ribbed tube with the outer diameter of 38.1 mm and the thickness of 7.5 mm. The test section was thermally insulated as horizontal direction. Based on the experimental results, it was found that pressure had a noticeable effect on the frictional pressure drop of the mental results, and that pressure had a noticeable effect on the frictional pressure drop of the steam-water two-phase flow, and the frictional pressure drop factor of the steam-water two-phase flow decreased with an increase in pressure. The frictional pressure drop factor of the steam-water two-phase flow tends to one near the critical pressure. As steam quality increased, the frictional pressure drop factor of the steam-water two-phase flow first increased, and then it had a decreasing tendency. With an increase in mass velocity, the frictional pressure drop factor of the steam-water two-phase flow decreased. Correlations of the frictional pressure drop factor of the steam-water two-phase flow had been provided. (authors)

  8. Sociodemographic risk factors and correlates of dementia in older Malaysians.

    Science.gov (United States)

    Hamid, Tengku Aizan; Krishnaswamy, Saroja; Abdullah, Siti Suhailah; Momtaz, Yadollah Abolfathi

    2010-01-01

    The rapid expansion of the aged population in Malaysia is expected to greatly increase the number of persons with dementia in the country. However, data on dementia prevalence at the national level is lacking, and little is known about the sociodemographic risk factors and correlates of dementia. This paper describes a nationwide study of dementia prevalence and its sociodemographic risk factors and health correlates among older Malaysians. In the nationwide study, the Mental Health and Quality of Life of Older Malaysians, AGECAT-GMS was used to diagnose dementia in a nationally representative sample of 2,980 persons aged 60 and above. The prevalence rate of dementia was 14.3%. Higher dementia prevalences were found in oldest age (26.3%), women (19.7%), no formal education (24.1%), Bumiputeras (32.2%), unmarried (19.4%), unemployed (31.3%) and very poor on self-rated health (33.3%). Multivariate logistic regression analyses showed that older age, female gender, no formal education, ethnicity and very poor self-rated health were independent risk factors and correlates of dementia. Relatively higher prevalence rates of dementia in older Malaysians were accounted for by greater proportions without education, Malay and Bumiputera ethnicity, and other unknown factors which should be further investigated. Copyright © 2011 S. Karger AG, Basel.

  9. [Correlations between wild Polygonatum odoratum quality and main ecological factors].

    Science.gov (United States)

    Bu, Jing; Li, Deng-Wu; Wang, Dong-Mei

    2012-06-01

    By the methods of stepwise regression, principal component analysis, and grey relational grade analysis, this paper studied the correlations between the effective components (polysaccharides and water- and alcohol-soluble substances) contents and antioxidant activity of wild Polygonatum odoratum in different places and the ecological factors. Among the test ecological factors, the mean air temperature in January and in July, mean annual precipitation, frost-free period, and soil pH and total potassium were the main factors affecting the effective component contents of P. odoratum, with a contribution rate of 99.0%. As compared with soil factors, climatic factors made more contribution to the effective component contents. Soil total potassium was the key factor controlling the effective component contents, mean annual precipitation was the main decision factor, and mean air temperature in January was the main limiting factor. The plant polysaccharides and water-soluble substance contents were the key factors affecting the antioxidant activity of P. odoratum, and the capability of P. odoratum in excavating DPPH free radical increased with increasing contents of polysaccharides and water-soluble substances.

  10. Correlation between microstructure and internal friction in a Zr41.2-Ti13.8-Cu12.5-Ni8- Be22.5-Fe2 bulk metallic glass

    International Nuclear Information System (INIS)

    Wang, Q.; Pelletier, J.M.; Da Dong, Y.; Ji, Y.F.; Xiu, H.

    2004-01-01

    The microstructural evolution in a Zr-Ti-Cu-Ni-Be-Fe bulk metallic glass (BMG) has been investigated by measurements of dynamical shear modulus and internal friction combined with other analytical methods such as differential scanning calorimetry (DSC), X-ray diffraction (XRD) and high resolution transmission electron microscopy (TEM). When heated from room temperature up to 873 K, the as-received BMG exhibits an exponential increase in internal friction accompanying the strong decrease of storage modulus and the presence of the first loss modulus peak during the dynamic glass transition, which can be well described using quasi-point defect model. The correlative changes of the mechanical response at higher temperature are associated with the crystallisation process of the supercooled liquid phase, which occurs in four different stages. It is shown that the main crystallisation process is completed in the first two stages. With further increasing temperature, the remaining amorphous phases crystallise and/or the metastable crystalline phases are transformed into the stable ones. Isothermal annealing were also performed at temperatures in the supercooled liquid region far below the onset temperature of the crystallisation process (T x ). Their influence on microstucture and internal friction behaviour of the BMG is also presented in this paper. The most striking result is that the internal friction is very sensitive to the local atomic short range ordering induced by the preheating treatment

  11. Bootstrap Confidence Intervals for Ordinary Least Squares Factor Loadings and Correlations in Exploratory Factor Analysis

    Science.gov (United States)

    Zhang, Guangjian; Preacher, Kristopher J.; Luo, Shanhong

    2010-01-01

    This article is concerned with using the bootstrap to assign confidence intervals for rotated factor loadings and factor correlations in ordinary least squares exploratory factor analysis. Coverage performances of "SE"-based intervals, percentile intervals, bias-corrected percentile intervals, bias-corrected accelerated percentile…

  12. Aphid incidence and its correlation with different environmental factors

    OpenAIRE

    Hasan, M.R; Ahmad, M.; Rahman, M.H; Haque, M.A

    2009-01-01

    The aphid incidence and its correlation with environmental factors were studied. Mustard variety “Sampad” was used as test crop. Aphid incidence varied significantly at various parts of mustard plant and time of the day. The highest number of aphid was observed in the vegetative parts of the mustard plant in the morning. High cloudiness, relative humidity and dew point favoured the aphid population and slight rain fall quickly declined the aphid population. Among the different environmental f...

  13. non-genetic factors and correlation studies in cattle.

    African Journals Online (AJOL)

    Irgang, R. Dillard, E.U., Tess, M.W. and Robison, O.W.,. 1985. Selection for weaning weight and post-weaning gain in Hereford cattle. III. Correlated responses to selection in milk yield, preweaning and post weaning traits. J. Anim. Sci. 60:1156. Kars, A.A., Easmus, G.J. and . Van der Westhuizen, J.,. 1994. Factors influencing ...

  14. Fanning friction (f and colburn (j factors of a louvered fin and flat tube compact heat exchanger

    Directory of Open Access Journals (Sweden)

    Karthik Pooranachandran

    2017-01-01

    Full Text Available In the present study, the heat transfer and pressure drop characteristics of air over the louvered fins in a compact heat exchanger, used as a radiator in the automobiles have been experimentally investigated. The experiments were conducted at various flow rates of air and the results showed a decrease in goodness factor of 22.7% with respect to increase in Reynolds number from 231 to 495. The experimental results were compared with the CFD results and the ‘f’ and ‘j’ factors from the CFD analysis are in good agreement with the experimental data. Also, the experimental ‘f’ and ‘j’ factors were compared with the predicted values from the available correlations in the literature for the louvered fin and tube compact heat exchangers. The large deviation of the predicted results revealed that the correlations are not reliable for the design of the compact heat exchanger. Hence, the CFD analysis is more advantageous for the optimal design of compact heat exchanger, which also reduces the experimentation time and cost.

  15. Experimental investigation of single-phase flow friction in narrow annuli

    International Nuclear Information System (INIS)

    Sun Zhongning; Sun Licheng; Yan Changqi; Huang Weitang

    2004-01-01

    Experimental investigations of water flow friction in horizontal narrow annuli, with gap sizes of 0.57-3.08 mm, were carried out. The tests involved both laminar and turbulent flow regimes. The critical Reynolds number transited from laminar flow to turbulent flow was examed and observed. The friction factors obtained from experiments were compared with conventional correlations evaluated results, and the influences of channel scale and eccentricity on flow friction characteristics were discussed. It was found that fluid friction in turbulent regime could be predicted by conventional correlations with satisfied degree, but both values and varying trend of that vs. r i /r o in laminar regime were obviously departure from theoretically results when the gap sizes were less than 2.0 mm, and the critical Reynolds number was slightly less then 2300 when the gap sizes were less than 1.0 mm

  16. KINEMATICS FRICTION PAIR FOR EXAMPLE NEEDLE BEARINGS

    Directory of Open Access Journals (Sweden)

    Jerzy NACHIMOWICZ

    2014-06-01

    Full Text Available The present study concerns certain phenomena that take place in the needle roller bearing. The friction that generates the anti-torque of a friction pair is the major factor that influences the needle bearing’s wear. In the needle bearing there occur two predominant types of friction: the rolling friction and the sliding friction, and both are subject to examination. The study presents recordings and analysis of the movements of all needle bearing’s rolling elements. The examination was carried out on a special examination stand that precisely emulates the real conditions of the needle bearing’s work. Carefully prepared examination methods enable recording and analyzing frictions in the bearing, estimating a sphere within which the load is shifted, and calculating the coefficient of friction.

  17. On form factors and correlation functions in twistor space

    Energy Technology Data Exchange (ETDEWEB)

    Koster, Laura [Institut für Mathematik, Institut für Physik und IRIS Adlershof,Humboldt-Universität zu Berlin,Zum Großen Windkanal 6, 12489 Berlin (Germany); Mitev, Vladimir [PRISMA Cluster of Excellence, Institut für Physik, WA THEP,Johannes Gutenberg-Universität Mainz,Staudingerweg 7, 55128 Mainz (Germany); Staudacher, Matthias [Institut für Mathematik, Institut für Physik und IRIS Adlershof,Humboldt-Universität zu Berlin,Zum Großen Windkanal 6, 12489 Berlin (Germany); Wilhelm, Matthias [Niels Bohr Institute, Copenhagen University,Blegdamsvej 17, 2100 Copenhagen Ø (Denmark)

    2017-03-24

    In this paper, we continue our study of form factors and correlation functions of gauge-invariant local composite operators in the twistor-space formulation of N=4 super Yang-Mills theory. Using the vertices for these operators obtained in our recent papers (DOI: 10.1103/PhysRevLett.117.011601; 10.1007/JHEP06(2016)162 ), we show how to calculate the twistor-space diagrams for general N{sup k}MHV form factors via the inverse soft limit, in analogy to the amplitude case. For general operators without α-dot indices, we then reexpress the NMHV form factors from the position-twistor calculation in terms of momentum twistors, deriving and expanding on a relation between the two twistor formalisms previously observed in the case of amplitudes. Furthermore, we discuss the calculation of generalized form factors and correlation functions as well as the extension to loop level, in particular providing an argument promised in https://www.doi.org/10.1002/prop.201400085.

  18. On form factors and correlation functions in twistor space

    International Nuclear Information System (INIS)

    Koster, Laura; Mitev, Vladimir; Staudacher, Matthias; Wilhelm, Matthias

    2017-01-01

    In this paper, we continue our study of form factors and correlation functions of gauge-invariant local composite operators in the twistor-space formulation of N=4 super Yang-Mills theory. Using the vertices for these operators obtained in our recent papers (DOI: 10.1103/PhysRevLett.117.011601; 10.1007/JHEP06(2016)162 ), we show how to calculate the twistor-space diagrams for general N k MHV form factors via the inverse soft limit, in analogy to the amplitude case. For general operators without α-dot indices, we then reexpress the NMHV form factors from the position-twistor calculation in terms of momentum twistors, deriving and expanding on a relation between the two twistor formalisms previously observed in the case of amplitudes. Furthermore, we discuss the calculation of generalized form factors and correlation functions as well as the extension to loop level, in particular providing an argument promised in https://www.doi.org/10.1002/prop.201400085.

  19. Elastomeric friction

    Science.gov (United States)

    Vorvolakos, Katherine

    This dissertation examines the tribology of PDMS (polydimethylsiloxane) elastomers from a practical and a fundamental perspective. We examine the adhesive, energetic, and tribological properties of several commercial biofouling release coatings, and show that adhesive (and bioadhesive) release from an elastomer depends on the friction of its surface. Having shown that friction is an obstacle to release, we lubricate a model PDMS network by incorporating linear unreactive PDMS oils varying in molecular weight (0.8--423 kg/mol). Surface segregation upon curing depends on molecular weight and mass percentage. Atomic Force Microscopy (AFM) is used to detect the thickness of the lubricant layer. Surprisingly, high-viscosity oils lubricate better than low-viscosity oils, indicating a non-hydrodynamic lubrication. Applying this technology to a commercial elastomer, we see an improvement in bioadhesive release capabilities, as evidenced by a reduced tenacity of mussel adhesive protein. In comparing entangled polymer melts to crosslinked elastomers, we encountered an opportunity to study the tribology of the latter. We studied the effects of molecular weight, velocity, and temperature on the friction of crosslinked PDMS elastomers sliding against two model surfaces: a self-assembled monolayer (SAM) of n-hexadecylsilane, and a thin (˜100mum) film of polystyrene (PS). The change from smooth to stick-slip (unstable) interfacial sliding occurs at a distinct velocity on each surface, implying that it's not necessarily attributable to a bulk glass transition of the PDMS, as popularly believed. The peak shear stress attained immediately before stick-slip sliding is found to be linear with the shear modulus raised to an exponent n of ¾, in contrast with the predictions of Chernyak and Leonov ( n = 1). Low-velocity behavior differs greatly between the SAM and the PS, implying a mechanistic difference. Whereas on the SAM, sliding likely proceeds purely by stochastic adsorption and

  20. Materials characterization of explanted polypropylene hernia mesh: Patient factor correlation.

    Science.gov (United States)

    Smith, Sarah E; Cozad, Matthew J; Grant, David A; Ramshaw, Bruce J; Grant, Sheila A

    2016-02-01

    This study quantitatively assessed polypropylene (PP) hernia mesh degradation and its correlation with patient factors including body mass index, tobacco use, and diabetes status with the goal of improving hernia repair outcomes through patient-matched mesh. Thirty PP hernia mesh explants were subjected to a tissue removal process followed by assessment of their in vivo degradation using Fourier transform infrared, differential scanning calorimetry, and thermogravimetric analysis analyses. Results were then analyzed with respect to patient factors (body mass index, tobacco use, and diabetes status) to determine their influence on in vivo hernia mesh oxidation and degradation. Twenty of the explants show significant surface oxidation. Tobacco use exhibits a positive correlation with modulated differential scanning calorimetry melt temperature and exhibits significantly lower TGA decomposition temperatures than non-/past users. Chemical and thermal characterization of the explanted meshes indicate measurable degradation while in vivo regardless of the patient population; however, tobacco use is correlated with less oxidation and degradation of the polymeric mesh possibly due to a reduced inflammatory response. © The Author(s) 2015.

  1. Clinical correlates of resilience factors in geriatric depression.

    Science.gov (United States)

    Laird, Kelsey T; Lavretsky, Helen; Paholpak, Pattharee; Vlasova, Roza M; Roman, Michael; St Cyr, Natalie; Siddarth, Prabha

    2018-01-16

    Traditional perspectives conceptualize resilience as a trait and depression as resulting from resilience deficiency. However, research indicates that resilience varies substantially even among adults who are clinically depressed, as well as across the lifespan of an individual. Few studies have investigated resilience in depression, and even fewer have examined resilience in depressed older adults. Three hundred thirty-seven adults ≥60 years with major depressive disorder completed the Connor-Davidson Resilience Scale (CD-RISC) and measures of mental health, quality of life (QOL), and medical comorbidity. Exploratory factor analysis was used to explore the factor structure of the CD-RISC. Correlations and general linear models were used to examine associations between resilience and other variables. The rotated component matrix indicated a four-factor model. Sorting of items by highest factor loading revealed constructs associated with (1) grit, (2) active coping self-efficacy, (3) accommodative coping self-efficacy, and (4) spirituality. Resilience was significantly correlated with increased age, lower cognitive functioning, greater cerebrovascular risk, and greater medical comorbidity. Resilience was negatively associated with mental health symptoms (depression, apathy, and anxiety) and positively associated with QOL. The final optimal model identified less depression, less apathy, greater medical comorbidity, higher QOL, and minority (non-White) race as factors that significantly explained variability in resilience. Resilience was significantly associated with a range of mental health constructs in a sample of older adults with depression. Future clinical trials and dismantling studies may help determine whether interventions targeting grit, active coping, accommodative coping, and spirituality can increase resilience and help prevent and treat depression in older adults.

  2. Scaling of permeabilities and friction factors of homogeneously expanding gas-solids fluidized beds: Geldart’s A powders and magnetically stabilized beds

    Directory of Open Access Journals (Sweden)

    Hristov Jordan Y.

    2006-01-01

    Full Text Available The concept of a variable friction factor of fluid-driven de form able powder beds undergoing fluidization is discussed. The special problem discussed addresses the friction factor and bed permeability relationships of Geldart’s A powders and magnetically stabilized beds in axial fields. Governing equations and scaling relation ships are developed through three approaches (1 Minimization of the pressure drop with respect to the fluid velocity employing the Darcy-Forchheimer equation together with the Richardson-Zaki scaling law, (2 Minimization of the pres sure drop across an equivalent-channel replacing the actual packed beds by a straight pipe with bed-equivalent obstacle of a simple geometry, and (3 Entropy minimization method applied in cases of the Darcy-Forchheimer equation and the equivalent-channel model. Bed-to-surface heat transfer coefficients are commented in the context of the porosity/length scale relationships developed. Both the pressure drop curves developments and phase diagram de signs are illustrated by applications of the intersection of asymptotes technique to beds exhibiting certain degree of cohesion.

  3. Numerical analysis of friction factor for a fully developed turbulent flow using k–ε turbulence model with enhanced wall treatment

    Directory of Open Access Journals (Sweden)

    Muhammad Ahsan

    2014-12-01

    Full Text Available The aim of this study is to formulate a computational fluid dynamics (CFD model that can illustrate the fully turbulent flow in a pipe at higher Reynolds number. The flow of fluids in a pipe network is an important and widely studied problem in any engineering industry. It is always significant to see the development of a fluid flow and pressure drop in a pipe at higher Reynolds number. A finite volume method (FVM solver with k–ε turbulence model and enhanced wall treatment is used first time to investigate the flow of water at different velocities with higher Reynolds number in a 3D pipe. Numerical results have been presented to illustrate the effects of Reynolds number on turbulence intensity, average shear stress and friction factor. Friction factor is used to investigate the pressure drop along the length of the pipe. The contours of wall function are also presented to investigate the effect of enhanced wall treatment on a fluid flow. A maximum Reynolds number is also found for which the selected pipe length is sufficient to find a full developed turbulent flow at outlet. The results of CFD modeling are validated by comparing them with available data in literature. The model results have been shown good agreement with experimental and co-relation data.

  4. Suicide During Perinatal Period: Epidemiology, Risk Factors and Clinical Correlates

    Directory of Open Access Journals (Sweden)

    Laura Orsolini

    2016-08-01

    Full Text Available Perinatal period may pose a great challenge for the clinical management and treatment of psychiatric disorders in women. In fact, several mental illnesses can arise during pregnancy and/or following childbirth. Suicide and infanticide have been considered relatively rare events during the perinatal period. However, in some mental disorders (i.e. postpartum depression, bipolar disorder, postpartum psychosis, etc. have been reported a higher risk of suicidal ideation, suicide attempt or suicide. Therefore, a complete screening of mothers’ mental health should also take into account thoughts of suicide and thoughts about harming infants as well. Clinicians should carefully monitor and early identify related clinical manifestations, potential risk factors and alarm symptoms related to suicide. The present paper aims at providing a focused review about epidemiological data, risk and protective factors and an overview about the main clinical correlates associated with the suicidal behaviour during the pregnancy and postpartum period.

  5. Solar and seasonal dependence of ion frictional heating

    Directory of Open Access Journals (Sweden)

    J. A. Davies

    1999-05-01

    Full Text Available Ion frictional heating constitutes one of the principal mechanisms whereby energy, originating in the solar wind, is deposited into the Earth's ionosphere and ultimately the neutral atmosphere. Common programme observations by the EISCAT UHF radar system, spanning the years 1984 to 1995, provide the basis for a comprehensive statistical study of ion frictional heating, results of which are documented in this and a previous paper by the authors. In the present work, the authors demonstrate the solar and seasonal dependence of the universal time distribution of frictional heating, and explain these results with reference to corresponding dependences of the ion velocity. Although EISCAT observes a significant increase in the occurrence of enhanced ion velocities associated with increased solar activity, the latter characterised according to the prevailing 10.7 cm solar flux, this is not reflected to such an extent in the occurrence of frictional heating. It is suggested that this is a consequence of the decreased neutral atmosphere response times associated with active solar conditions, resulting from the higher ionospheric plasma densities present. Seasonal effects on the diurnal distribution of ion frictional heating are well explained by corresponding variations in ionospheric convection, the latter principally a result of geometrical factors. It is noted that, over the entire dataset, the variations in the unperturbed F-region ion temperature, required to implement the identification criterion for ion heating, are highly correlated with model values of thermospheric temperature.Keywords. Ionosphere (auroral ionosphere; ionosphere-atmosphere interactions; plasma temperature and density

  6. Numerical estimation of wall friction ratio near the pseudo-critical point with CFD-models

    International Nuclear Information System (INIS)

    Angelucci, M.; Ambrosini, W.; Forgione, N.

    2013-01-01

    In this paper, the STAR-CCM+ CFD code is used in the attempt to reproduce the values of friction factor observed in experimental data at supercritical pressures at various operating conditions. A short survey of available data and correlations for smooth pipe friction in circular pipes puts the basis for the discussion, reporting observed trends of friction factor in the liquid-like and the gas-like regions and within the transitional region across the pseudo-critical temperature. For smooth pipes, a general decrease of the friction factor in the transitional region is reported, constituting one of the relevant effects to be predicted by the computational fluid-dynamic models. A limited number of low-Reynolds number models are adopted, making use of refined near-wall discretisation as required by the constraint y + < 1 at the wall. In particular, the Lien k–ε and the SST k–ω models are considered. The values of the wall shear stress calculated by the code are then post-processed on the basis of bulk fluid properties to obtain the Fanning and then the Darcy–Weisbach friction factors, based on their classical definitions. The obtained values are compared with those provided by experimental tests and correlations, finding a reasonable qualitative agreement. Expectedly, the agreement is better in the gas-like and liquid-like regions, where fluid property changes are moderate, than in the transitional region, where the trends provided by available correlations are reproduced only in a qualitative way

  7. Acoustics of friction

    Science.gov (United States)

    Akay, Adnan

    2002-04-01

    This article presents an overview of the acoustics of friction by covering friction sounds, friction-induced vibrations and waves in solids, and descriptions of other frictional phenomena related to acoustics. Friction, resulting from the sliding contact of solids, often gives rise to diverse forms of waves and oscillations within solids which frequently lead to radiation of sound to the surrounding media. Among the many everyday examples of friction sounds, violin music and brake noise in automobiles represent the two extremes in terms of the sounds they produce and the mechanisms by which they are generated. Of the multiple examples of friction sounds in nature, insect sounds are prominent. Friction also provides a means by which energy dissipation takes place at the interface of solids. Friction damping that develops between surfaces, such as joints and connections, in some cases requires only microscopic motion to dissipate energy. Modeling of friction-induced vibrations and friction damping in mechanical systems requires an accurate description of friction for which only approximations exist. While many of the components that contribute to friction can be modeled, computational requirements become prohibitive for their contemporaneous calculation. Furthermore, quantification of friction at the atomic scale still remains elusive. At the atomic scale, friction becomes a mechanism that converts the kinetic energy associated with the relative motion of surfaces to thermal energy. However, the description of the conversion to thermal energy represented by a disordered state of oscillations of atoms in a solid is still not well understood. At the macroscopic level, friction interacts with the vibrations and waves that it causes. Such interaction sets up a feedback between the friction force and waves at the surfaces, thereby making friction and surface motion interdependent. Such interdependence forms the basis for friction-induced motion as in the case of

  8. Kinetic Friction of Sport Fabrics on Snow

    Directory of Open Access Journals (Sweden)

    Werner Nachbauer

    2016-03-01

    Full Text Available After falls, skiers or snowboarders often slide on the slope and may collide with obstacles. Thus, the skier’s friction on snow is an important factor to reduce incidence and severity of impact injuries. The purpose of this study was to measure snow friction of different fabrics of ski garments with respect to roughness, speed, and contact pressure. Three types of fabrics were investigated: a commercially available ski overall, a smooth downhill racing suit, and a dimpled downhill racing suit. Friction was measured for fabrics taped on a short ski using a linear tribometer. The fabrics’ roughness was determined by focus variation microscopy. Friction coefficients were between 0.19 and 0.48. Roughness, friction coefficient, and friction force were highest for the dimpled race suit. The friction force of the fabrics was higher for the higher contact pressure than for the lower one at all speeds. It was concluded that the main friction mechanism for the fabrics was dry friction. Only the fabric with the roughest surface showed friction coefficients, which were high enough to sufficiently decelerate a sliding skier on beginner and intermediate slopes.

  9. Sliding Friction of Copper

    National Research Council Canada - National Science Library

    Liu, Tung

    1963-01-01

    .... With less clean surfaces, the coefficient of friction obtained was about 0.4. Since the degree of cleanliness cannot be controlled quantitatively, the friction - load curve of sliding copper pairs in air exhibits a bifurcation characteristic...

  10. Large Friction Anisotropy of a Polydiacetylene Monolayer

    International Nuclear Information System (INIS)

    Burns, A.R.; Carpick, R.W.; Sasaki, D.Y.

    1999-01-01

    Friction force microscopy measurements of a polydiacetylene monolayer film reveal a 300% friction anisotropy that is correlated with the film structure. The film consists of a monolayer of the red form of N-(2-ethanol)- 10,12 pentacosadiynamide, prepared on a Langmuir trough and deposited on a mica substrate. As confirmed by atomic force microscopy and fluorescence microscopy, the monolayer consists of domains of linearly oriented conjugated backbones with pendant hydrocarbon side chains above and below the backbones. Maximum friction occurs when the sliding direction is perpendicular to the backbone. We propose that the backbones impose anisotropic packing of the hydrocarbon side chains which leads to the observed friction anisotropy. Friction anisotropy is therefore a sensitive, optically-independent indicator of polymer backbone direction and monolayer structural properties

  11. Amontonian frictional behaviour of nanostructured surfaces.

    Science.gov (United States)

    Pilkington, Georgia A; Thormann, Esben; Claesson, Per M; Fuge, Gareth M; Fox, Oliver J L; Ashfold, Michael N R; Leese, Hannah; Mattia, Davide; Briscoe, Wuge H

    2011-05-28

    With nanotextured surfaces and interfaces increasingly being encountered in technological and biomedical applications, there is a need for a better understanding of frictional properties involving such surfaces. Here we report friction measurements of several nanostructured surfaces using an Atomic Force Microscope (AFM). These nanostructured surfaces provide well defined model systems on which we have tested the applicability of Amontons' laws of friction. Our results show that Amontonian behaviour is observed with each of the surfaces studied. However, no correlation has been found between measured friction and various surface roughness parameters such as average surface roughness (R(a)) and root mean squared (rms) roughness. Instead, we propose that the friction coefficient may be decomposed into two contributions, i.e., μ = μ(0) + μ(g), with the intrinsic friction coefficient μ(0) accounting for the chemical nature of the surfaces and the geometric friction coefficient μ(g) for the presence of nanotextures. We have found a possible correlation between μ(g) and the average local slope of the surface nanotextures. This journal is © the Owner Societies 2011

  12. Correlation between Nerve Growth Factor (NGF with Brain Derived Neurotropic Factor (BDNF in Ischemic Stroke Patient

    Directory of Open Access Journals (Sweden)

    Joko Widodo

    2016-05-01

    Full Text Available Background: The neurotrophins nerve growth factor (NGF and brain-derived neurotrophic factor (BDNF is a family of polypeptides that play critical role during neuronal development, appear to mediate protective role on neurorepair in ischemic stroke. Naturally in adult brain neurorepair process consist of: angiogenesis, neurogenesis, and neuronal plasticity, it can also be stimulated by endogenous neurorepair. In this study we observed correlation between NGF and BDNF ischemic stroke patient’s onset: 7-30 and over 30 days. Methods: This is cross sectional study on 46 subjects aged 38 – 74 years old with ischemic stroke from The Indonesian Central Hospital of Army Gatot Subroto Jakarta. Diagnosis of ischemic stroke was made using clinical examination and magnetic resonance imaging (MRI by neurologist. Subjects were divided into 2 groups based on stroke onset: 7 – 30 days (Group A: 19 subjects and > 30 days (Group B: 27 Subjects. Serum NGF levels were measured with ELISA method and BDNF levels were measured using multiplex method with Luminex Magpix. Results: Levels of NGF and BDNF were significantly different between onset group A and B (NGF p= 0.022, and BDNF p=0.008, with mean levels NGF in group A higher than group B, indicating that BDNF levels is lower in group A than group B. There was no significant correlation between NGF and BDNF levels in all groups. Conclusion: The variations in neurotrophic factor levels reflect an endogenous attempt at neuroprotection against biochemical and molecular changes after ischemic stroke. NGF represents an early marker of brain injury while BDNF recovery is most prominent during the first 14 days after onsite but continuous for more than 30 days. There is no significant correlation between NGF and BDNF in each group.  

  13. Skin Friction Measurements Using Luminescent Oil Films

    Science.gov (United States)

    Husen, Nicholas M.

    As aircraft are designed to a greater extent on computers, the need for accurate and fast CFD algorithms has never been greater. The development of CFD algorithms requires experimental data against which CFD output can be validated and from which insight about flow physics can be acquired. Skin friction, in particular, is an important quantity to predict with CFD, and experimental skin friction data sets aid not only with the validation of the CFD predictions, but also in tuning the CFD models to predict specific flow fields. However, a practical experimental technique for collecting spatially and temporally resolved skin friction data on complex models does not yet exist. This dissertation develops and demonstrates a new luminescent oil film skin friction meter which can produce spatially-resolved quantitative steady and unsteady skin friction data on models with complex curvature. The skin friction acting on the surface of a thin film of oil can be approximated by the expression tauw =mu ouh/h, where mu o is the dynamic viscosity of the oil, uh is the velocity of the surface of the oil film, and h is the thickness of the oil film. The new skin friction meter determines skin friction by measuring h and uh. The oil film thickness h is determined by ratioing the intensity of the fluorescent emissions from the oil film with the intensity of the incident light which is scattered from the surface of the model. When properly calibrated, that ratio provides an absolute oil film thickness value. This oil film thickness meter is therefore referred as the Ratioed-Image Film-Thickness (RIFT) Meter. The oil film velocity uh is determined by monitoring the evolution of tagged molecules within the oil film: Photochromic molecules are dissolved into the fluorescent oil and a pattern is written into the oil film using an ultraviolet laser. The evolution of the pattern is recorded, and standard cross-correlation techniques are applied to the resulting sequence of images. This

  14. Social cognition in schizophrenia: factor structure, clinical and functional correlates.

    Science.gov (United States)

    Buck, Benjamin E; Healey, Kristin M; Gagen, Emily C; Roberts, David L; Penn, David L

    2016-08-01

    Social cognition is consistently impaired in people with schizophrenia, separable from general neurocognition, predictive of real-world functioning and amenable to psychosocial treatment. Few studies have empirically examined its underlying factor structure. This study (1) examines the factor structure of social cognition in both a sample of individuals with schizophrenia-spectrum disorders and non-clinical controls and (2) explores relationships of factors to neurocognition, symptoms and functioning. A factor analysis was conducted on social cognition measures in a sample of 65 individuals with schizophrenia or schizoaffective disorder, and 50 control participants. The resulting factors were examined for their relationships to symptoms and functioning. Results suggested a two-factor structure in the schizophrenia sample (social cognition skill and hostile attributional style) and a three-factor structure in the non-clinical sample (hostile attributional style, higher-level inferential processing and lower-level cue detection). In the schizophrenia sample, the social cognition skill factor was significantly related to negative symptoms and social functioning, whereas hostile attributional style predicted positive and general psychopathology symptoms. The factor structure of social cognition in schizophrenia separates hostile attributional style and social cognition skill, and each show differential relationships to relevant clinical variables in schizophrenia.

  15. A Correlation between the Ultimate Shear Stress and the Thickness Affected by Intermetallic Compounds in Friction Stir Welding of Dissimilar Aluminum Alloy–Stainless Steel Joints

    Directory of Open Access Journals (Sweden)

    Florent Picot

    2018-03-01

    Full Text Available In this work, Friction Stir Welding (FSW was applied to join a stainless steel 316L and an aluminum alloy 5083. Ranges of rotation and translation speeds of the tool were used to obtain welding samples with different heat input coefficients. Depending on the process parameters, the heat generated by FSW creates thin layers of Al-rich InterMetallic Compound (IMC mainly composed of FeAl3, identified by energy dispersive spectrometry. Traces of Fe2Al5 were also depicted in some samples by X-ray diffraction analysis and transmission electron microscopy. Monotonous tensile tests performed on the weld joint show the existence of a maximum mechanical resistance for a judicious choice of rotation and translation speeds. It can be linked to an affected zone of average thickness of 15 µm which encompass the presence of IMC and the chaotic mixing caused by plastic deformation in this area. A thickness of less than 15 µm is not sufficient to ensure a good mechanical resistance of the joint. For a thickness higher than 15 µm, IMC layers become more brittle and less adhesive due to high residual stresses which induces numerous cracks after cooling. This leads to a progressive decrease of the ultimate shear stress supported by the bond.

  16. Correlates of Bio-Psychosocial Factors on Perceived Body Image ...

    African Journals Online (AJOL)

    DrNneka

    Doi: http://dx.doi.org/10.4314/afrrev.v10i1.20. Correlates of .... (2000) viewed weight gain and fat as part of normal development in adolescent, yet a ... who do not exercise. Struggling with excessive weight gain is a major problem in Nigeria today. This may drive people in search for a truly healthful weight loss solution.

  17. Are "g" and the General Factor of Personality (GFP) Correlated?

    Science.gov (United States)

    Irwing, Paul; Booth, Tom; Nyborg, Helmuth; Rushton, J. Philippe

    2012-01-01

    We examined whether the General Factor of Personality (GFP) is related to the "g" factor of cognitive ability using data from the Vietnam Experience Study which randomly sampled 4462 Vietnam War veterans from a total sample of about five million Vietnam era army veterans. Exclusionary criteria included passing a fitness test, achieving a…

  18. FRICTION-BOON OR BANE IN ORTHODONTICS

    Directory of Open Access Journals (Sweden)

    Sameer

    2015-11-01

    Full Text Available OBJECTIVE: Most fixed appliance techniques involve some degree of sliding between brackets and arch wires. A sound knowledge of the various factors affecting the magnitude of friction is of paramount importance to the clinician. The present study was performed to evaluate and compare the frictional resistance and characteristics between self-ligating brackets and pre-adjusted edgewise brackets with different types of ligation. MATERIALS AND METHODS: Tidy's frictional test design was used to simulate retraction of tooth along with artificial saliva to simulate wet conditions in oral cavity. The jig with this assembly was mounted on the Instron machine with the cross head moving upwards at a speed of 5mm/min. The movable bracket was suspended from the load cell of the testing machine, while the jig was mounted on cross head of machine and the load cell readings were recorded on digital display. Following wires are used 0.016 HANT, 0.019X 0.025HANT, 0.019X 0.025 SS, 0.021X 0.025 SS wires are used. The brackets used were 0.022 slot Damon, 0.022 Smart clip and 0.022 slot MBT system. RESULTS: Self ligating brackets were shown to produce lesser friction when compared to the conventional brackets used with modules, and stainless steel ligatures. Damon self-ligating brackets produce a least friction of all the brackets used in the study. Stainless steel ligatures produced the least friction compared to elastomeric. CONCLUSION: Self ligation brackets produce lesser friction than the conventional brackets ligated with elastomeric modules and stainless steel ligature. Damon self-ligating brackets produce a least friction of all the brackets used in the study width of the bracket was also found to be directly proportional to the friction produced 0.0016HANT with elastomeric modules produce more friction due increase in flexibility of wire.

  19. On conditions of negativity of friction resistance for nonstationary modes of blood flow and possible mechanism of affecting of environmental factors on energy effectiveness of cardiovascular system function

    Directory of Open Access Journals (Sweden)

    Sergey G. Chefranov

    2013-05-01

    Full Text Available It is shown that initiated by action of molecular viscosity impulse flow, directed usually from the moving fluid to limiting it solid surface, can, under certain conditions, turn to zero and get negative values in the case of non-stationary flow caused by alternating in time longitudinal (along the pipe axis pressure gradient. It is noted that this non-equilibrium mechanism of negative friction resistance in the similar case of pulsating blood flow in the blood vessels, in addition to the stable to turbulent disturbances swirled blood flow structure providing, can also constitute hydro-mechanical basis of the observed but not explained yet paradoxically high energy effectiveness of the normal functioning of the cardiovascular system (CVS. We consider respective mechanism of affecting on the stability of the normal work of CVS by environmental variable factors using shifting of hydro-dynamic mode with negative resistance realization range boundaries and variation of linear hydrodynamic instability leading to the structurally stable swirled blood flow organization.

  20. Influence of roughness parameters on coefficient of friction under ...

    Indian Academy of Sciences (India)

    mm). Peak count. FD. Fractal dimension. Figure 3. Correlation coefficient between coefficient of friction and roughness parameters under lubricated conditions. White and black bars represent positive and negative correlations, respectively.

  1. Classical limit of diagonal form factors and HHL correlators

    Energy Technology Data Exchange (ETDEWEB)

    Bajnok, Zoltan [MTA Lendület Holographic QFT Group, Wigner Research Centre,H-1525 Budapest 114, P.O.B. 49 (Hungary); Janik, Romuald A. [Institute of Physics, Jagiellonian University,ul. Łojasiewicza 11, 30-348 Kraków (Poland)

    2017-01-16

    We propose an expression for the classical limit of diagonal form factors in which we integrate the corresponding observable over the moduli space of classical solutions. In infinite volume the integral has to be regularized by proper subtractions and we present the one, which corresponds to the classical limit of the connected diagonal form factors. In finite volume the integral is finite and can be expressed in terms of the classical infinite volume diagonal form factors and subvolumes of the moduli space. We analyze carefully the periodicity properties of the finite volume moduli space and found a classical analogue of the Bethe-Yang equations. By applying the results to the heavy-heavy-light three point functions we can express their strong coupling limit in terms of the classical limit of the sine-Gordon diagonal form factors.

  2. Cluster synchronization of dry friction oscillators

    Directory of Open Access Journals (Sweden)

    Marszal Michał

    2018-01-01

    Full Text Available Synchronization is a well known phenomenon in non-linear dynamics and is treated as correlation in time of at least two different processes. In scope of this article, we focus on complete and cluster synchronization in the systems of coupled dry friction oscillators, coupled by linear springs. The building block of the system is the classic stick-slip oscillator, which consists of mass, spring and belt-mass friction interface. The Stribeck friction itself is modelled using Stribeck friction model with exponential non-linearity. The oscillators in the systems are connected in nearest neighbour fashion, both in open and closed ring topology. We perform a numerical study of the properties of the dynamics of the systems in question, in two-parameter space (coupling coefficient vs. angular excitation frequency and explore the possible configurations of cluster synchronization.

  3. Vascular Cognitive Impairment: risk factors and brain MRI correlates

    NARCIS (Netherlands)

    Reijmer, Y.D.

    2012-01-01

    Vascular disease plays an important role in the development of dementia, also in patients diagnosed with Alzheimer’s disease. Risk factors such as hypertension, obesity, and type 2 diabetes, are associated with a two-fold increased risk of cognitive dysfunction and dementia. The development of

  4. Occupational stress factors as correlates of job performance among ...

    African Journals Online (AJOL)

    The study investigates the relationship between occupational stress factors and job performance among some Nigerian industrial workers (n = 300, males = 133, females = 67, mean age = 47.3, SD = 5.6). The Occupational Stress Questionnaire and Workers' Performance Rating Scale were employed to collect data from ...

  5. Enhanced nanoscale friction on fluorinated graphene.

    Science.gov (United States)

    Kwon, Sangku; Ko, Jae-Hyeon; Jeon, Ki-Joon; Kim, Yong-Hyun; Park, Jeong Young

    2012-12-12

    Atomically thin graphene is an ideal model system for studying nanoscale friction due to its intrinsic two-dimensional (2D) anisotropy. Furthermore, modulating its tribological properties could be an important milestone for graphene-based micro- and nanomechanical devices. Here, we report unexpectedly enhanced nanoscale friction on chemically modified graphene and a relevant theoretical analysis associated with flexural phonons. Ultrahigh vacuum friction force microscopy measurements show that nanoscale friction on the graphene surface increases by a factor of 6 after fluorination of the surface, while the adhesion force is slightly reduced. Density functional theory calculations show that the out-of-plane bending stiffness of graphene increases up to 4-fold after fluorination. Thus, the less compliant F-graphene exhibits more friction. This indicates that the mechanics of tip-to-graphene nanoscale friction would be characteristically different from that of conventional solid-on-solid contact and would be dominated by the out-of-plane bending stiffness of the chemically modified graphene. We propose that damping via flexural phonons could be a main source for frictional energy dissipation in 2D systems such as graphene.

  6. Surface Friction of Polyacrylamide Hydrogel Particles

    Science.gov (United States)

    Cuccia, Nicholas; Burton, Justin

    Polyacrylamide hydrogel particles have recently become a popular system for modeling low-friction, granular materials near the jamming transition. Because a gel consists of a polymer network filled with solvent, its frictional behavior is often explained using a combination of hydrodynamic lubrication and polymer-surface interactions. As a result, the frictional coefficient can vary between 0.001 and 0.03 depending on several factors such as contact area, sliding velocity, normal force, and the gel surface chemistry. Most tribological measurements of hydrogels utilize two flat surfaces, where the contact area is not well-defined. We have built a custom, low-force tribometer to measure the single-contact frictional properties of spherical hydrogel particles on flat hydrogel surfaces under a variety of measurement conditions. At high velocities (> 1 cm/s), the friction coefficient depends linearly on velocity, but does not tend to zero at zero velocity. We also compare our measurements to solid particles (steel, glass, etc.) on hydrogel surfaces, which exhibit larger frictional forces, and show less dependence on velocity. A physical model for the friction which includes the lubrication layer between the deformed surfaces will be discussed. National Science Foundation Grant No. 1506446.

  7. Study on friction behaviour of brake shoe materials for mining hoist

    Science.gov (United States)

    Ungureanu, M.; Ungureanu, N. S.; Crăciun, I.

    2017-02-01

    The friction coefficient in the brake linkages has an important influence on the braking efficiency and safety of machines. The paper presents a method for the study of the friction coefficient of the friction couple brake shoe-drum for mining hoist. In this context, it is interesting to define the friction coefficient, not just according to the materials in contact, but according to the entire ensemble of tribological factors of the friction couple.

  8. INSOMNIA AND CORRELATION WITH PSYCHOSOCIAL FACTORS IN PRIMARY HEALTH CARE

    OpenAIRE

    Made Gede Cahyadi Permana

    2013-01-01

    Insomnia is regarded as sleep disorder that most often affects people in the world, both in primary and in the presence of comorbid conditions. Based on those facts, insomnia could be a serious problem at the level of primary health care. General Practitioner should be able to diagnose insomnia and able to perform the appropriate treatment for the patient. Psychosocial factors may related to the degree of severity of insomnia, among others are health status, depression, dysfunctional beliefs ...

  9. Prediction of wall friction for fluids at supercritical pressure with CFD models

    International Nuclear Information System (INIS)

    Angelucci, M.; Ambrosini, W.; Forgione, N.

    2011-01-01

    In this paper, the STAR-CCM+ CFD code is used in the attempt to reproduce the values of friction factor observed in experimental data at supercritical pressures at various operating conditions. A short survey of available data and correlations for smooth pipe friction in circular pipes puts the basis for the discussion, reporting observed trends of friction factor in the liquid-like and the gas-like regions and within the transitional region around the pseudo-critical temperature. For smooth pipes, a general decrease of the friction factor in the transitional region is reported, constituting one of the relevant effects to be predicted by the computational fluid-dynamic models. A limited number of low-Reynolds number models is adopted, making use of refined near-wall discretisations as required by the constraint y + < 1 at the wall. In particular, the Lien k-ε and the SST k-ω models are considered. The values of the wall shear stress calculated by the code are then post-processed on the basis of bulk fluid properties to obtain the Fanning and then the Darcy-Weisbach friction factors, basing on their classical definitions. The obtained values are compared with those provided by experimental tests and correlations, finding a reasonable qualitative agreement. Expectedly, the agreement is better in the gas-like and liquid-like regions, where fluid property changes are moderate, than in the transitional region, where the trends provided by available correlations are reproduced only in a qualitative way. (author)

  10. Dissection of genomic correlation matrices of US Holsteins using multivariate factor analysis

    Science.gov (United States)

    Aim of the study was to compare correlation matrices between direct genomic predictions for 31 production, fitness and conformation traits both at genomic and chromosomal level in US Holstein bulls. Multivariate factor analysis was used to quantify basic features of correlation matrices. Factor extr...

  11. Risk factors for child abuse: quantitative correlational design.

    Science.gov (United States)

    Ben-Natan, Merav; Sharon, Ira; Barbashov, Polina; Minasyan, Yulia; Hanukayev, Isabella; Kajdan, David; Klein-Kremer, Adi

    2014-01-01

    The aim of this research study is to identify risk factors typical of different types of suspected child abuse reported at a hospital. The study was based on 114 cases of children for whom some type of abuse was reported. Physical abuse was the most frequently reported of all types of suspected child abuse. Most victims of sexual abuse were female and at least half the cases of neglect and physical abuse were attributed to parents. Most cases were identified in the emergency room by nurses. Children older than 10 were more susceptible to physical abuse and neglect. © 2014.

  12. Nonlinear friction dynamics on polymer surface under accelerated movement

    Directory of Open Access Journals (Sweden)

    Yuuki Aita

    2017-04-01

    Full Text Available Nonlinear phenomena on the soft material surface are one of the most exciting topics of chemical physics. However, only a few reports exist on the friction phenomena under accelerated movement, because friction between two solid surfaces is considered a linear phenomenon in many cases. We aim to investigate how nonlinear accelerated motion affects friction on solid surfaces. In the present study, we evaluate the frictional forces between two polytetrafluoroethylene (PTFE resins using an advanced friction evaluation system. On PTFE surfaces, the normalized delay time δ, which is the time lag in the response of the friction force to the accelerated movement, is observed in the pre-sliding friction process. Under high-velocity conditions, kinetic friction increases with velocity. Based on these experimental results, we propose a two-phase nonlinear model including a pre-sliding process (from the beginning of sliding of a contact probe to the establishment of static friction and a kinetic friction process. The present model consists of several factors including velocity, acceleration, stiffness, viscosity, and vertical force. The findings reflecting the viscoelastic properties of soft material is useful for various fields such as in the fabrication of clothes, cosmetics, automotive materials, and virtual reality systems as well as for understanding friction phenomena on soft material surfaces.

  13. Polymer friction Molecular Dynamics

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N.; Persson, Bo N. J.

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively...... independent of molecular length. For polymer sliding on polymer the friction is significantly larger, and dependent on the molecular chain length. In both cases, the shear stresses are proportional to the squeezing pressure and finite at zero load, indicating an adhesional contribution to the friction force....

  14. Friction mediated by redox-active supramolecular connector molecules.

    Science.gov (United States)

    Bozna, B L; Blass, J; Albrecht, M; Hausen, F; Wenz, G; Bennewitz, R

    2015-10-06

    We report on a friction study at the nanometer scale using atomic force microscopy under electrochemical control. Friction arises from the interaction between two surfaces functionalized with cyclodextrin molecules. The interaction is mediated by connector molecules with (ferrocenylmethyl)ammonium end groups forming supramolecular complexes with the cyclodextrin molecules. With ferrocene connector molecules in solution, the friction increases by a factor of up to 12 compared to control experiments without connector molecules. The electrochemical oxidation of ferrocene to ferrocenium causes a decrease in friction owing to the lower stability of ferrocenium-cyclodextrin complex. Upon switching between oxidative and reduction potentials, a change in friction by a factor of 1.2-1.8 is observed. Isothermal titration calorimetry reveals fast dissociation and rebinding kinetics and thus an equilibrium regime for the friction experiments.

  15. Friction stir welding tool

    Science.gov (United States)

    Tolle,; Charles R. , Clark; Denis E. , Barnes; Timothy, A [Ammon, ID

    2008-04-15

    A friction stir welding tool is described and which includes a shank portion; a shoulder portion which is releasably engageable with the shank portion; and a pin which is releasably engageable with the shoulder portion.

  16. Paediatric treadmill friction injuries.

    Science.gov (United States)

    Jeremijenko, Luke; Mott, Jonathan; Wallis, Belinda; Kimble, Roy

    2009-05-01

    The aim of this study was to report on the severity and incidence of children injured by treadmills and to promote the implementation of safety standards. This retrospective review of children with treadmill friction injuries was conducted in a single tertiary-level burns centre in Australia between January 1997 and June 2007. The study revealed 37 children who sustained paediatric treadmill friction injuries. This was a presentation of 1% of all burns. Thirty-three (90%) of the injuries occurred in the last 3.5 years (January 2004 to June 2007). The modal age was 3.2 years. Thirty-three (90%) injuries were either full thickness or deep partial friction burns. Eleven (30%) required split thickness skin grafts. Of those who became entrapped, 100% required skin grafting. This study found that paediatric treadmill friction injuries are severe and increasing in incidence. Australian standards should be developed, implemented and mandated to reduce this preventable and severe injury.

  17. Skin tribology: Science friction?

    OpenAIRE

    Heide, E. van der; Zeng, X.; Masen, M.A.

    2013-01-01

    The application of tribological knowledge is not just restricted to optimizing mechanical and chemical engineering problems. In fact, effective solutions to friction and wear related questions can be found in our everyday life. An important part is related to skin tribology, as the human skin is frequently one of the interacting surfaces in relative motion. People seem to solve these problems related to skin friction based upon a trial-and-error strategy and based upon on our sense for touch....

  18. Generic expansion of the Jastrow correlation factor in polynomials satisfying symmetry and cusp conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lüchow, Arne, E-mail: luechow@rwth-aachen.de [Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen (Germany); Jülich Aachen Research Alliance (JARA-HPC), 52056 Aachen (Germany); Sturm, Alexander; Schulte, Christoph; Haghighi Mood, Kaveh [Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen (Germany)

    2015-02-28

    Jastrow correlation factors play an important role in quantum Monte Carlo calculations. Together with an orbital based antisymmetric function, they allow the construction of highly accurate correlation wave functions. In this paper, a generic expansion of the Jastrow correlation function in terms of polynomials that satisfy both the electron exchange symmetry constraint and the cusp conditions is presented. In particular, an expansion of the three-body electron-electron-nucleus contribution in terms of cuspless homogeneous symmetric polynomials is proposed. The polynomials can be expressed in fairly arbitrary scaling function allowing a generic implementation of the Jastrow factor. It is demonstrated with a few examples that the new Jastrow factor achieves 85%–90% of the total correlation energy in a variational quantum Monte Carlo calculation and more than 90% of the diffusion Monte Carlo correlation energy.

  19. Generic expansion of the Jastrow correlation factor in polynomials satisfying symmetry and cusp conditions.

    Science.gov (United States)

    Lüchow, Arne; Sturm, Alexander; Schulte, Christoph; Haghighi Mood, Kaveh

    2015-02-28

    Jastrow correlation factors play an important role in quantum Monte Carlo calculations. Together with an orbital based antisymmetric function, they allow the construction of highly accurate correlation wave functions. In this paper, a generic expansion of the Jastrow correlation function in terms of polynomials that satisfy both the electron exchange symmetry constraint and the cusp conditions is presented. In particular, an expansion of the three-body electron-electron-nucleus contribution in terms of cuspless homogeneous symmetric polynomials is proposed. The polynomials can be expressed in fairly arbitrary scaling function allowing a generic implementation of the Jastrow factor. It is demonstrated with a few examples that the new Jastrow factor achieves 85%-90% of the total correlation energy in a variational quantum Monte Carlo calculation and more than 90% of the diffusion Monte Carlo correlation energy.

  20. Reflections on Friction in Quantum Mechanics

    Directory of Open Access Journals (Sweden)

    Yair Rezek

    2010-08-01

    Full Text Available Distinctly quantum friction effects of three types are surveyed: internalfriction, measurement-induced friction, and quantum-fluctuation-induced friction. We demonstrate that external driving will lead to quantum internal friction, and critique the measurement-based interpretation of friction. We conclude that in general systems will experience internal and external quantum friction over and beyond the classical frictional contributions.

  1. The Butterfly Effect: Correlations Between Modeling in Nuclear-Particle Physics and Socioeconomic Factors

    CERN Document Server

    Pia, Maria Grazia; Bell, Zane W.; Dressendorfer, Paul V.

    2010-01-01

    A scientometric analysis has been performed on selected physics journals to estimate the presence of simulation and modeling in physics literature in the past fifty years. Correlations between the observed trends and several social and economical factors have been evaluated.

  2. Friction in volcanic environments

    Science.gov (United States)

    Kendrick, Jackie E.; Lavallée, Yan

    2016-04-01

    Volcanic landscapes are amongst the most dynamic on Earth and, as such, are particularly susceptible to failure and frictional processes. In rocks, damage accumulation is frequently accompanied by the release of seismic energy, which has been shown to accelerate in the approach to failure on both a field and laboratory scale. The point at which failure occurs is highly dependent upon strain-rate, which also dictates the slip-zone properties that pertain beyond failure, in scenarios such as sector collapse and pyroclastic flows as well as the ascent of viscous magma. High-velocity rotary shear (HVR) experiments have provided new opportunities to overcome the grand challenge of understanding faulting processes during volcanic phenomena. Work on granular ash material demonstrates that at ambient temperatures, ash gouge behaves according to Byerlee's rule at low slip velocities, but is slip-weakening, becoming increasingly lubricating as slip ensues. In absence of ash along a slip plane, rock-rock friction induces cataclasis and heating which, if sufficient, may induce melting (producing pseudotachylyte) and importantly, vesiculation. The viscosity of the melt, so generated, controls the subsequent lubrication or resistance to slip along the fault plane thanks to non-Newtonian suspension rheology. The shear-thinning behaviour and viscoelasticity of frictional melts yield a tendency for extremely unstable slip, and occurrence of frictional melt fragmentation. This velocity-dependence acts as an important feedback mechanism on the slip plane, in addition to the bulk composition, mineralogy and glass content of the magma, that all influence frictional behaviour. During sector collapse events and in pyroclastic density currents it is the frictional properties of the rocks and ash that, in-part, control the run-out distance and associated risk. In addition, friction plays an important role in the eruption of viscous magmas: In the conduit, the rheology of magma is integral

  3. Interfacial friction damping properties in magnetorheological elastomers

    International Nuclear Information System (INIS)

    Fan, Yanceng; Gong, Xinglong; Xuan, Shouhu; Zhang, Wei; Zheng, Jian; Jiang, Wanquan

    2011-01-01

    In this study, the interfacial friction damping properties of magnetorheological elastomers (MREs) were investigated experimentally. Two kinds of carbonyl iron particles, with sizes of 1.1 µm and 9.0 µm, were used to fabricate four MRE samples, whose particle weight fractions were 10%, 30%, 60% and 80%, respectively. Their microstructures were observed using an environmental scanning electron microscope (SEM). The dynamic performances of these samples, including shear storage modulus and loss factor were measured with a modified dynamic mechanical analyzer (DMA). The experimental results indicate that MRE samples fabricated with 1.1 µm carbonyl iron particles have obvious particle agglomeration, which results in the fluctuation of loss factor compared with other MRE samples fabricated with large particle sizes. The analysis implies that the interfacial friction damping mainly comes from the frictional sliding at the interfaces between the free rubber and the particles

  4. Spouse correlations in cardiovascular risk factors and the effect of marriage duration.

    Science.gov (United States)

    Knuiman, M W; Divitini, M L; Bartholomew, H C; Welborn, T A

    1996-01-01

    Spouse correlations in cardiovascular risk factors were investigated using data on 2,836 spouse pairs collected in the Busselton Population Health Surveys over the period 1966-1981. The risk factors considered were systolic blood pressure, diastolic blood pressure, body mass index, triceps fatfold, cholesterol, and forced expiratory volume (1 second). Statistically significant positive correlations (p marriage duration (trend p forced expiratory volume (p = 0.16) also decreased with marriage duration, and correlations for cholesterol (p = 0.61) and triceps fatfold (p = 0.99) increased with marriage duration. These results suggest that there is spousal concordance in cardiovascular risk factors. The lack of consistent increasing trends in the correlations with marriage duration suggests that assortative mating may be a more likely explanation than the sharing of a common environment.

  5. Diabetes and male sex are key risk factor correlates of the extent of coronary artery calcification

    DEFF Research Database (Denmark)

    Nicoll, Rachel; Zhao, Ying; Wiklund, Urban

    2017-01-01

    BACKGROUND AND AIMS: Although much has been written about the conventional cardiovascular risk factor correlates of the extent of coronary artery calcification (CAC), few studies have been carried out on symptomatic patients. This paper assesses the potential ability of risk factors to associate ...

  6. A new detrended semipartial cross-correlation analysis: Assessing the important meteorological factors affecting API

    International Nuclear Information System (INIS)

    Shen, Chen-Hua

    2015-01-01

    To analyze the unique contribution of meteorological factors to the air pollution index (API), a new method, the detrended semipartial cross-correlation analysis (DSPCCA), is proposed. Based on both a detrended cross-correlation analysis and a DFA-based multivariate-linear-regression (DMLR), this method is improved by including a semipartial correlation technique, which is used to indicate the unique contribution of an explanatory variable to multiple correlation coefficients. The advantages of this method in handling nonstationary time series are illustrated by numerical tests. To further demonstrate the utility of this method in environmental systems, new evidence of the primary contribution of meteorological factors to API is provided through DMLR. Results show that the most important meteorological factors affecting API are wind speed and diurnal temperature range, and the explanatory ability of meteorological factors to API gradually strengthens with increasing time scales. The results suggest that DSPCCA is a useful method for addressing environmental systems. - Highlights: • A detrended multiple linear regression is shown. • A detrended semipartial cross correlation analysis is proposed. • The important meteorological factors affecting API are assessed. • The explanatory ability of meteorological factors to API gradually strengthens with increasing time scales.

  7. Comparison of Deadtime Correction Factors for Passive Neutron Multiplicity Counting of Correlated and Non-Correlated Neutron Sources

    International Nuclear Information System (INIS)

    Evans, L.G.; Norman, P.I.; Croft, S.; Menaa, N.

    2009-01-01

    Traditional deadtime correction methods for Passive Neutron Multiplicity Counting (PNMC) have been found to be potentially accuracy limiting at high average (or sustained) count rates and in the case where highly correlated rates occur over a short coincidence gate width (high instantaneous rates associated with high multiplicity bursts). It is costly to retrofit new hardware to existing assay systems to reduce the effects of deadtime, thus it is advantageous to develop and implement new deadtime correction algorithms as an alternative approach to ameliorate this problem. Future counter designs trend towards higher efficiencies and shorter die-away times and hence these designs will also present the need for improved deadtime treatments as they will get applied to more demanding applications. For these reasons, deadtime correction techniques for PNMC are currently being re-visited by both the waste characterisation and safeguards communities in the nuclear industry. A Monte Carlo approach has been established to simulate deadtime behaviour in PNMC systems and applied to this long standing problem. The form of the deadtime correction factor has been investigated for non-correlated (e.g. AmLi) neutron sources and will be extended to correlated (e.g. Cf-252) neutron sources. This paper addresses the practical correction method in each case. The aim of this work has been to aid research into the development of an improved and unified approach to deadtime correction for different multiplicity distributions. Simulation provides a convenient means to examine the range of applicability of current analytical models. (authors)

  8. The dependence of the nuclear charge form factor on short range correlations and surface fluctuation effects

    International Nuclear Information System (INIS)

    Massen, S. E.; Garistov, V. P.; Grypeos, M. E.

    1996-01-01

    The effects of nuclear surface fluctuations on harmonic oscillator elastic charge form factor of light nuclei are investigated, simultaneously approximating the short-range correlations through a Jastrow correlation factor. Inclusion of the surface fluctuation effects within this description, by truncating the cluster expansion at the two-body part, is found to improve somewhat the fit to the elastic charge form-factor of 16 O and 40 Ca. However, the convergence of the cluster expansion is expected to deteriorate. An additional finding is that surface-fluctuation correlations produce a drastic change in the asymptotic behaviour of the point-proton form-factor, which now falls off quite slowly (i.e. as const.q -4 ) at large values of the momentum transfer q

  9. A CLINICO-HISTOPATHOLOGICAL STUDY OF FRICTIONAL MELANOSIS

    Directory of Open Access Journals (Sweden)

    Keerthi Jampani

    2016-06-01

    Full Text Available OBJECTIVE The aim of the present study was to analyse different clinical patterns of frictional melanosis and to evaluate whether sun exposure is a causative or contributing factor for frictional melanosis. Furthermore, histopathology with haematoxylin and eosin along with special stains for amyloid like Congo red was done. METHODS 50 patients with clinical diagnosis of frictional melanosis participated in this study. INCLUSION CRITERIA Patients of all ages and both sexes with classical clinical features suggestive of frictional melanosis are included. EXCLUSION CRITERIA Patients having pigmentation over areas where the frictional melanosis presents classically but have been using chemicals, hair dyes and other agents which can cause photocontact dermatitis have been excluded from the study. A detailed history regarding duration of illness, progression and precipitating factors along with detailed clinical examination regarding the location of the lesions and type of lesions was done and patients were subjected to skin biopsy after obtaining a written consent. RESULTS Out of 50 cases, 39 (78% were confirmed with histopathology as frictional melanosis and 11(22% as macular amyloidosis. Among patients of frictional melanosis, 56.41% had only skin lesions. In macular amyloidosis 63.63% patients had itching along with skin lesions. In Frictional melanosis the most frequently involved site was extensor aspect of arm (78.48%. The most frequently involved site in macular amyloidosis was extensor aspect of forearm (93.34%. CONCLUSION In this study a total number of 50 patients with clinical presentation of frictional melanosis were analysed with female preponderance. Amyloid deposition is seen in those skin biopsy specimens taken from area of friction with sun exposure, which suggests that sun exposure could be one of the predisposing factors for macular amyloidosis. Thus, these findings confirm that frictional melanosis is a variant of macular

  10. Internal friction in zirconium

    International Nuclear Information System (INIS)

    Miyada-Naborikawa, L.T.; De Batist, R.; Eersels, L.

    1981-01-01

    The effect of type (bending, tension or torsion) and temperature (100 K, 300 K) of deformation on the internal friction spectrum of well-annealed polycrystalline zirconium has been investigated at frequencies of about 1 Hz and about 100 Hz. The result of ageing at temperatures not higher than 300 K on both the modulus and the internal friction is also described. The observed peaks are discussed in terms of either dislocation relaxation or dislocation point defect interaction effects and combined with literature data to obtain better defined values for the relaxation parameters

  11. Frictional coefficient depending on active friction radius with BPV ...

    African Journals Online (AJOL)

    The comparison of estimated frictional coefficient from numerical output is in agreement with vis-à-vis corresponding similar computed from the virtual braking system model in the Simulink. The results indicated that highest frictional coefficient of 0.7 was obtained on the piston side of the rotor disc and active friction radius is ...

  12. Fingerprints are unlikely to increase the friction of primate fingerpads.

    Science.gov (United States)

    Warman, Peter H; Ennos, A Roland

    2009-07-01

    It is generally assumed that fingerprints improve the grip of primates, but the efficiency of their ridging will depend on the type of frictional behaviour the skin exhibits. Ridges would be effective at increasing friction for hard materials, but in a rubbery material they would reduce friction because they would reduce contact area. In this study we investigated the frictional performance of human fingertips on dry acrylic glass using a modified universal mechanical testing machine, measuring friction at a range of normal loads while also measuring the contact area. Tests were carried out on different fingers, fingers at different angles and against different widths of acrylic sheet to separate the effects of normal force and contact area. The results showed that fingertips behaved more like rubbers than hard solids; their coefficients of friction fell at higher normal forces and friction was higher when fingers were held flatter against wider sheets and hence when contact area was greater. The shear stress was greater at higher pressures, suggesting the presence of a biofilm between the skin and the surface. Fingerprints reduced contact area by a factor of one-third compared with flat skin, however, which would have reduced the friction; this casts severe doubt on their supposed frictional function.

  13. Research on Annular Frictional Pressure Loss of Hydraulic-Fracturing in Buckling Coiled Tubing

    Science.gov (United States)

    Liu, Bin; Cai, Meng; Li, Junliang; Xu, Yongquan; Wang, Peng

    2018-01-01

    Compared with conventional hydraulic fracturing, coiled tubing (CT) annular delivery sand fracturing technology is a new method to enhance the recovery ratio of low permeability reservoir. Friction pressure loss through CT has been a concern in fracturing. The small diameter of CT limits the cross-sectional area open to flow, therefore, to meet large discharge capacity, annular delivery sand technology has been gradually developed in oilfield. Friction pressure is useful for determining the required pump horsepower and fracturing construction design programs. Coiled tubing can buckle when the axial compressive load acting on the tubing is greater than critical buckling load, then the geometry shape of annular will change. Annular friction pressure loss elevates dramatically with increasing of discharge capacity, especially eccentricity and CT buckling. Despite the frequency occurrence of CT buckling in oilfield operations, traditionally annular flow frictional pressure loss considered concentric and eccentric annuli, not discussing the effects of for discharge capacity and sand ratio varying degree of CT buckling. The measured data shows that the factors mentioned above cannot be ignored in the prediction of annular pressure loss. It is necessary to carry out analysis of annulus flow pressure drop loss in coiled tubing annular with the methods of theoretical analysis and numerical simulation. Coiled tubing buckling has great influence on pressure loss of fracturing fluid. Therefore, the correlations have been developed for turbulent flow of Newtonian fluids and Two-phase flow (sand-liquid), and that improve the friction pressure loss estimation in coiled tubing operations involving a considerable level of buckling. Quartz sand evidently increases pressure loss in buckling annular, rising as high as 40%-60% more than fresh water. Meanwhile, annulus flow wetted perimeter increases with decreasing helical buckling pitch of coiled tubing, therefore, the annulus flow

  14. Universal Aging Mechanism for Static and Sliding Friction of Metallic Nanoparticles.

    Science.gov (United States)

    Feldmann, Michael; Dietzel, Dirk; Tekiel, Antoni; Topple, Jessica; Grütter, Peter; Schirmeisen, André

    2016-07-08

    The term "contact aging" refers to the temporal evolution of the interface between a slider and a substrate usually resulting in increasing friction with time. Current phenomenological models for multiasperity contacts anticipate that such aging is not only the driving force behind the transition from static to sliding friction, but at the same time influences the general dynamics of the sliding friction process. To correlate static and sliding friction on the nanoscale, we show experimental evidence of stick-slip friction for nanoparticles sliding on graphite over a wide dynamic range. We can assign defined periods of aging to the stick phases of the particles, which agree with simulations explicitly including contact aging. Additional slide-hold-slide experiments for the same system allow linking the sliding friction results to static friction measurements, where both friction mechanisms can be universally described by a common aging formalism.

  15. Environmental Factors Correlated with Size of Bacterial Populations in a Polluted Stream

    Science.gov (United States)

    Brasfeild, Helen

    1972-01-01

    Samples of water were taken from a polluted zone of the Gallinas River and analyzed as to numbers of total bacteria, coliforms, and fecal streptococci. Environmental factors measured were temperature, pH and concentrations of detergent, nitrate plus nitrite nitrogen, sulfate, chloride, bicarbonate, and phosphate. Thirty-two observations were made from 12 March through 22 July 1971. Stepwise multiple linear regression analyses of the data were carried out by computer to determine which of the environmental factors were significantly correlated with numbers of bacteria present. A multiple linear regression equation was constructed for each bacteriological parameter as a function of significant variables only. Log total bacteria was correlated positively with bicarbonate, phosphate, and detergent concentrations. Log coliforms was correlated positively with phosphate and sulfate concentrations and negatively with chloride concentration. Log fecal streptococci was correlated positively with bicarbonate and chloride concentrations. PMID:4627965

  16. On the Application of Correction Factor for Axial Power Distribution to CHF Correlation Development

    International Nuclear Information System (INIS)

    Kim, Kang Hoon; Kim, Hong Ju; Yang, Seung Geun; Park, Eung Jun; Hwang, Sun Tack; Chung, Sun Kyo

    2005-01-01

    The axial heat flux distribution in nuclear reactors is invariably non-uniform. Thus it is very important to validate the general applicability of CHF correlation developed with limited types of axial heat flux distribution to actual situation of various axial power shapes in reactor operation. Per the recent fuel development, CHF testing is performed for chopped cosine axial heat flux distribution only. Thus it is inevitable to re-clarify the validity of correction factor for non-uniform axial heat flux distribution to support the general applicability of CHF correlation developed with data recently tested. Two ways of approach are considered to care the effects of axial power distribution in CHF correlation development. With the first method, CHF correlation is developed based on the data of uniform axial heat flux distribution only. To apply the correlation to the data of various axially non-uniform heat flux distribution, a factor such as Tong's F-factor is applied to the predicted value by the correlation itself to correct the effects of upstream memory on CHF. With the second approach, CHF correlation is developed based on whole data with the concept of equivalent uniform heat flux for the data of non-uniform axial heat flux distribution. The equivalent uniform heat flux is a measured CHF value for the data of uniform axial heat flux distribution, but it is a pseudo-CHF with a corrective factor for the data of non-uniform axial heat flux distribution. The corrective factor is applied to predict CHF for any non-uniform axial heat flux distribution

  17. Student figures in friction

    DEFF Research Database (Denmark)

    Nielsen, Gritt B.

    , students' room for participation in their own learning, influenced by demands for efficiency, flexibility and student-centred education. The thesis recasts the anthropological endeavour as one of ‘figuration work'. That is, ‘frictional events' are explored as moments when conflicting figures...

  18. Skin tribology: Science friction?

    NARCIS (Netherlands)

    Heide, E. van der; Zeng, X.; Masen, M.A.

    2013-01-01

    The application of tribological knowledge is not just restricted to optimizing mechanical and chemical engineering problems. In fact, effective solutions to friction and wear related questions can be found in our everyday life. An important part is related to skin tribology, as the human skin is

  19. Collets and friction

    Science.gov (United States)

    McIlraith, A. H.

    2005-07-01

    Conical sleeves, known as collets, have long been used for clamping sliding bodies to cylindrical columns in any desired position. Quantitative expressions for their properties are presented. Of particular interest is the ability of a collet to hold a shaft stationary against axial forces in either direction, and yet be able to release its grip with a minimum of additional force. This treatment relates the firmness of grip, the ease of release and the interface stresses to the cone angle, the coefficients of friction and the applied axial forces. The central part played by hysteresis is revealed. Experiments employing a test model give good support to the theoretical conclusions. They show that, up to the interface pressures reached, about 250 MPa, the friction between lubricated hardened steel and mild steel surfaces is independent of pressure. The strong dependence of friction on surface roughness is demonstrated. The possible adaptation of the collet test equipment to the measurement of friction at high interface pressures is touched upon. It could be a complementary alternative to the more flexible pin-on-disc method. With much larger working areas, it should have the advantages of better defined areas of contact, reduced ploughing effects and less leakage of lubricant.

  20. Friction enhancement in concertina locomotion of snakes

    Science.gov (United States)

    Marvi, Hamidreza; Hu, David L.

    2012-01-01

    Narrow crevices are challenging terrain for most organisms and biomimetic robots. Snakes move through crevices using sequential folding and unfolding of their bodies in the manner of an accordion or concertina. In this combined experimental and theoretical investigation, we elucidate this effective means of moving through channels. We measure the frictional properties of corn snakes, their body kinematics and the transverse forces they apply to channels of varying width and inclination. To climb channels inclined at 60°, we find snakes use a combination of ingenious friction-enhancing techniques, including digging their ventral scales to double their frictional coefficient and pushing channel walls transversely with up to nine times body weight. Theoretical modelling of a one-dimensional n-linked crawler is used to calculate the transverse force factor of safety: we find snakes push up to four times more than required to prevent sliding backwards, presumably trading metabolic energy for an assurance of wall stability. PMID:22728386

  1. Correlation of transforming growth factor-β1 and tumour necrosis factor levels with left ventricular function in Chagas disease

    Science.gov (United States)

    Curvo, Eduardo OV; Ferreira, Roberto R; Madeira, Fabiana S; Alves, Gabriel F; Chambela, Mayara C; Mendes, Veronica G; Sangenis, Luiz Henrique C; Waghabi, Mariana C; Saraiva, Roberto M

    2018-01-01

    BACKGROUND Transforming growth factor β1 (TGF-β1) and tumour necrosis factor (TNF) have been implicated in Chagas disease pathophysiology and may correlate with left ventricular (LV) function. OBJECTIVES We determined whether TGF-β1 and TNF serum levels correlate with LV systolic and diastolic functions and brain natriuretic peptide (BNP) serum levels in chronic Chagas disease. METHODS This cross-sectional study included 152 patients with Chagas disease (43% men; 57 ± 12 years old), classified as 53 patients with indeterminate form and 99 patients with cardiac form (stage A: 24, stage B: 25, stage C: 44, stage D: 6). TGF-β1, TNF, and BNP were determined by enzyme-linked immunosorbent assay ELISA. Echocardiogram was used to determine left atrial and LV diameters, as well as LV ejection fraction and diastolic function. FINDINGS TGF-b1 serum levels were lower in stages B, C, and D, while TNF serum levels were higher in stages C and D of the cardiac form. TGF-β1 presented a weak correlation with LV diastolic function and LV ejection fraction. TNF presented a weak correlation with left atrial and LV diameters and LV ejection fraction. CONCLUSIONS TNF is increased, while TGF-β1 is decreased in the cardiac form of chronic Chagas disease. TNF and TGF-β1 serum levels present a weak correlation with LV systolic and diastolic function in Chagas disease patients. PMID:29513876

  2. Internal rotor friction instability

    Science.gov (United States)

    Walton, J.; Artiles, A.; Lund, J.; Dill, J.; Zorzi, E.

    1990-01-01

    The analytical developments and experimental investigations performed in assessing the effect of internal friction on rotor systems dynamic performance are documented. Analytical component models for axial splines, Curvic splines, and interference fit joints commonly found in modern high speed turbomachinery were developed. Rotor systems operating above a bending critical speed were shown to exhibit unstable subsynchronous vibrations at the first natural frequency. The effect of speed, bearing stiffness, joint stiffness, external damping, torque, and coefficient of friction, was evaluated. Testing included material coefficient of friction evaluations, component joint quantity and form of damping determinations, and rotordynamic stability assessments. Under conditions similar to those in the SSME turbopumps, material interfaces experienced a coefficient of friction of approx. 0.2 for lubricated and 0.8 for unlubricated conditions. The damping observed in the component joints displayed nearly linear behavior with increasing amplitude. Thus, the measured damping, as a function of amplitude, is not represented by either linear or Coulomb friction damper models. Rotordynamic testing of an axial spline joint under 5000 in.-lb of static torque, demonstrated the presence of an extremely severe instability when the rotor was operated above its first flexible natural frequency. The presence of this instability was predicted by nonlinear rotordynamic time-transient analysis using the nonlinear component model developed under this program. Corresponding rotordynamic testing of a shaft with an interference fit joint demonstrated the presence of subsynchronous vibrations at the first natural frequency. While subsynchronous vibrations were observed, they were bounded and significantly lower in amplitude than the synchronous vibrations.

  3. Micromechanics of pseudo-single-asperity friction: Effects of nanometer-scale roughness

    Science.gov (United States)

    Li, Qunyang

    Nanometer-scale roughness on a solid surface has significant effects on friction, since inter-surface forces operate predominantly within a nanometer-scale gap distance in frictional contact. This thesis presents two novel atomic force microscope friction experiments, each using a gold surface sliding against a flat mica surface as the representative friction system. A diamagnetic lateral force calibrator (D-LFC) was invented to enable the accurate quantitative force measurements. In one of the experiment, a disk-shaped single nano-asperity of gold was used to measure the molecular level frictional behavior. The adhesive friction stress was measured to be 264 MPa and the molecular friction factor 0.0108 for a direct gold-mica contact in 30% humid air. The capillary force from the condensed water meniscuses was found to play an important role in magnifying the contact pressure to plastically deform the nano-asperities leading to the dramatic evolution of frictional responses. In the second experiment, the frictional response of a micrometer-scale asperity with nanometer-scale roughness exhibited a pseudo-single-asperity frictional behavior. However, the apparent friction stress, 40.5 MPa, fell well below the Hurtado-Kim model prediction for a smooth-single-asperity friction, exhibiting an apparent size-scale dependence of the friction stress. An interfacial roughness (IR) layer model was then developed to investigate the effects of roughness on pseudo-single-asperity friction. The model calculation shows that the nanometer-scale surface roughness is the major mechanism that explains the apparent size-scale dependence of the friction observed in the experiments. Furthermore, the analysis shows that the apparent friction stress as well as the apparent pressure-dependent fiction factor relies on the surface roughness. Both experimental and theoretical results suggest that the evolution status of surface roughness is one of the important internal variables for the

  4. PEBBLES Simulation of Static Friction and New Static Friction Benchmark

    International Nuclear Information System (INIS)

    Cogliati, Joshua J.; Ougouag, Abderrafi M.

    2010-01-01

    Pebble bed reactors contain large numbers of spherical fuel elements arranged randomly. Determining the motion and location of these fuel elements is required for calculating certain parameters of pebble bed reactor operation. This paper documents the PEBBLES static friction model. This model uses a three dimensional differential static friction approximation extended from the two dimensional Cundall and Strack model. The derivation of determining the rotational transformation of pebble to pebble static friction force is provided. A new implementation for a differential rotation method for pebble to container static friction force has been created. Previous published methods are insufficient for pebble bed reactor geometries. A new analytical static friction benchmark is documented that can be used to verify key static friction simulation parameters. This benchmark is based on determining the exact pebble to pebble and pebble to container static friction coefficients required to maintain a stable five sphere pyramid.

  5. Is there a genetic correlation between general factors of intelligence and personality?

    Science.gov (United States)

    Loehlin, John C; Bartels, Meike; Boomsma, Dorret I; Bratko, Denis; Martin, Nicholas G; Nichols, Robert C; Wright, Margaret J

    2015-06-01

    We tested a hypothesis that there is no genetic correlation between general factors of intelligence and personality, despite both having been selected for in human evolution. This was done using twin samples from Australia, the United States, the Netherlands, Great Britain, and Croatia, comprising altogether 1,748 monozygotic and 1,329 same-sex dizygotic twin pairs. Although parameters in the model-fitting differed among the twin samples, the genetic correlation between the two general factors could be set to zero, with a better fit if the U.S. sample was excepted.

  6. Factors controlling degree of correlation between ISEE 1 and ISEE 3 interplanetary magnetic field measurements

    International Nuclear Information System (INIS)

    Crooker, N.U.; Siscoe, G.L.; Russell, C.T.; Smith, E.J.

    1982-01-01

    The degree of correlation between ISEE 1 and ISEE 3 IMF measurements is highly variable. Approximately 200 two-hour periods when the correlation was good and 200 more when the correlation was poor are used to determine the relative control of several factors over the degree of correlation. Both IMF variance and spacecraft separation distance in the plane perpendicular to the earth-sun line exert substantial control. Good correlations are associated with high variance and distances less than 90 R/sub E/. During periods of highest variance, good correlations occur at distances beyond 90 R/sub E/ up to 120 R/sub E/, the maximum range of ISEE 1-ISEE 3 separation. Thus it appears that the scale size of magnetic features is larger when the variance is high. Abrupt changes in the correlation coefficient from poor to good or good to poor in adjacent two-hour intervals appear to be governed by the sense of change of IMF variance: changes in correlation from poor to good correspond to increasing variance and vice versa. The IMF orientation also exerts control over the degree of correlation. During periods of low variance, good correlations are most likely to occur when the distance between ISEE 1 and ISEE 3 perpendicular to the IMF is less than 20 R/sub E/. This scale size expands to approx.50 R/sub E/ during periods of high variance. Solar wind speed shows little control over the degree of correlation in the speed range 300--500 km/s

  7. Analysis of the correlative factors for velopharyngeal closure of patients with cleft palate after primary repair.

    Science.gov (United States)

    Chen, Qi; Li, Yang; Shi, Bing; Yin, Heng; Zheng, Guang-Ning; Zheng, Qian

    2013-12-01

    The objective of this study was to analyze the correlative factors for velopharyngeal closure of patients with cleft palate after primary repair. Ninety-five nonsyndromic patients with cleft palate were enrolled. Two surgical techniques were applied in the patients: simple palatoplasty and combined palatoplasty with pharyngoplasty. All patients were assessed 6 months after the operation. The postoperative velopharyngeal closure (VPC) rate was compared by χ(2) test and the correlative factors were analyzed with logistic regression model. The postoperative VPC rate of young patients was higher than that of old patients, the group with incomplete cleft palate was higher than the group with complete cleft palate, and combined palatoplasty with pharyngoplasty was higher than simple palatoplasty. Operative age, cleft type, and surgical technique were the contributing factors for postoperative VPC rate. Operative age, cleft type, and surgical technique were significant factors influencing postoperative VPC rate of patients with cleft palate. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. Temporal correlation analysis between malaria and meteorological factors in Motuo County, Tibet

    Directory of Open Access Journals (Sweden)

    Tang Linhua

    2011-03-01

    Full Text Available Abstract Background Malaria has been endemic in Linzhi Prefecture in the Tibet Autonomous Region (TAR over the past 20 years, especially in Motou County with a highest incidence in the country in recent years. Meteorological factors, such as rainfall, temperature and relative humidity in Motou County were unique compared to other areas in Tibet as well as other parts of China, thus the objective of this work was to analyse the temporal correlation between malaria incidence and meteorological factors in Motou County, in order to seek the particular interventions for malaria control. Methods The meteorological and malaria data during 1986-2009 in Motuo County were studied to analyse the statistical relationship between meteorological data time series and malaria incidence data series. Temporal correlation between malaria incidence and meteorological factors were analyzed using several statistical methods. Spearman correlation analysis was conducted to examine the association between monthly malaria incidence and meteorological variables. Cross-correlation analysis of monthly malaria incidence series and monthly meteorological data time series revealed the time lag(s of meteorological factors preceding malaria at which the series showed strongest correlation. Multiplicative seasonal auto-regressive integrated moving average (SARIMA models were used in the cross-correlation analysis with pre-whitening which remove seasonality and auto-correlation of meteorological data series. Differenced data analysis which called inter-annual analysis was carried out to find underlying relationship between malaria data series and meteorological data series. Results It has been revealed that meteorological variables, such as temperature, relative humidity and rainfall were the important environmental factors in the transmission of malaria. Spearman correlation analysis demonstrated relative humidity was greatest relative to malaria incidence and the correlation

  9. Systematic investigation of the fatigue performance of a friction stir welded low alloy steel

    International Nuclear Information System (INIS)

    Toumpis, Athanasios; Galloway, Alexander; Molter, Lars; Polezhayeva, Helena

    2015-01-01

    Highlights: • The fatigue behaviour of a friction stir welded low alloy steel has been assessed. • The welds’ fatigue lives outperform the International Institute of Welding’s recommendations for fusion welds. • The slow weld exhibits the best fatigue performance of the investigated welds. • Fracture surface analysis shows that minor embedded flaws do not offer crack initiation sites. • Process-related surface breaking flaws have a significant effect on the fatigue life. - Abstract: A comprehensive fatigue performance assessment of friction stir welded DH36 steel has been undertaken to address the relevant knowledge gap for this process on low alloy steel. A detailed set of experimental procedures specific to friction stir welding has been put forward, and the consequent study extensively examined the weld microstructure and hardness in support of the tensile and fatigue testing. The effect of varying welding parameters was also investigated. Microstructural observations have been correlated to the weldments’ fatigue behaviour. The typical fatigue performance of friction stir welded steel plates has been established, exhibiting fatigue lives well above the weld detail class of the International Institute of Welding even for tests at 90% of yield strength, irrespective of minor instances of surface breaking flaws which have been identified. An understanding of the manner in which these flaws impact on the fatigue performance has been established, concluding that surface breaking irregularities such as these produced by the tool shoulder’s features on the weld top surface can be the dominant factor for crack initiation under fatigue loading

  10. Mobility and Balance and Their Correlation with Physiological Factors in Elderly with Different Foot Postures

    Directory of Open Access Journals (Sweden)

    Aisyah Mohd Said

    2015-01-01

    Full Text Available This study determines (1 the correlation between mobility and balance performances with physiological factors and (2 the relationship between foot postures with anthropometric characteristics and lower limb characteristics among elderly with neutral, pronated, and supinated foot. A cross-sectional observational study was conducted in community-dwelling elderly (age: 69.86 ± 5.62 years. Participants were grouped into neutral (n=16, pronated (n=14, and supinated (n=14 foot based on the foot posture index classification. Anthropometric data (height, weight, and BMI, lower limb strength (5-STS and endurance (30 s chair rise test, mobility (TUG, and balance (FSST were determined. Data were analyzed using Spearman’s correlation coefficient. Body weight was negatively and moderately correlated (rs=-0.552, P<0.05 with mobility in supinated foot; moderate-to-high positive linear rank correlation was found between lower limb strength and mobility (rs=0.551 to 0.804, P<0.05 for pronated and neutral foot. Lower limb endurance was negatively and linearly correlated with mobility in pronated (rs=-0.699 and neutral (rs=-0.573 foot. No correlation was observed in balance performance with physiological factors in any of the foot postures. We can conclude that muscle function may be the most important feature to make movement possible in older persons regardless of the type of foot postures.

  11. Distinguishing narcissism and hostility: similarities and differences in interpersonal circumplex and five-factor correlates.

    Science.gov (United States)

    Ruiz, J M; Smith, T W; Rhodewalt, F

    2001-06-01

    Narcissism and hostility are both characterized by dysfunctional social interactions, including tendencies to perceive slights, experience anger, and behave aggressively. The aim of this study was to examine the similarities and differences of narcissism and hostility, using 2 conceptual tools-the interpersonal circumplex and the Five-factor model. In a sample of 292 undergraduate men and women, composite measures of hostility (i.e., Buss-Perry Aggression Questionnaire [Buss & Perry, 1992] and Cook-Medley Hostility [Cook & Medley, 1954] total scores) were inversely correlated with affiliation and unrelated to dominance. In contrast, composite narcissism scores (i.e., Narcissistic Personality Inventory) were positively correlated with dominance and inversely correlated with affiliation. Examination of components of these traits revealed additional similarities and differences, as did associations with other dimensions of the Five-factor model. These findings suggest that the traits of narcissism and hostility are distinguishable by their interpersonal referents, as are their components.

  12. Overlap Between the General Factor of Personality and Trait Emotional Intelligence: A Genetic Correlation Study

    NARCIS (Netherlands)

    D. van der Linden (Dimitri); Schermer, J.A. (Julie A.); E.L. de Zeeuw (Eveline); C.S. Dunkel (Curtis); K.A. Pekaar (Keri Anne); A.B. Bakker (Arnold); Vernon, P.A. (Philip A.); K.V. Petrides (K.)

    2017-01-01

    textabstractA previous meta-analysis (Van der Linden et al., Psychol Bull 143:36–52, 2017) showed that the General Factor of Personality (GFP) overlaps with ability as well as trait emotional intelligence (EI). The correlation between trait EI and the GFP was so high (ρ = 0.88) in that meta-analysis

  13. General Friction Model Extended by the Effect of Strain Hardening

    DEFF Research Database (Denmark)

    Nielsen, Chris V.; Martins, Paulo A.F.; Bay, Niels

    2016-01-01

    An extension to the general friction model proposed by Wanheim and Bay [1] to include the effect of strain hardening is proposed. The friction model relates the friction stress to the fraction of real contact area by a friction factor under steady state sliding. The original model for the real...... contact area as function of the normalized contact pressure is based on slip-line analysis and hence on the assumption of rigid-ideally plastic material behavior. In the present work, a general finite element model is established to, firstly, reproduce the original model under the assumption of rigid......-ideally plastic material, and secondly, to extend the solution by the influence of material strain hardening. This corresponds to adding a new variable and, therefore, a new axis to the general friction model. The resulting model is presented in a combined function suitable for e.g. finite element modeling...

  14. FEM simulation of friction testing method based on combined forward rod-backward can extrusion

    DEFF Research Database (Denmark)

    Nakamura, T; Bay, Niels; Zhang, Z. L

    1997-01-01

    A new friction testing method by combined forward rod-backward can extrusion is proposed in order to evaluate frictional characteristics of lubricants in forging processes. By this method the friction coefficient mu and the friction factor m can be estimated along the container wall and the conical...... in a mechanical press with aluminium alloy A6061 as the workpiece material and different kinds of lubricants. They confirm the analysis resulting in reasonable values for the friction coefficient and the friction factor....... curves are obtained by rigid-plastic FEM simulations in a combined forward rod-backward can extrusion process for a reduction in area R-b = 25, 50 and 70 percent in the backward can extrusion. It is confirmed that the friction factor m(p) on the punch nose in the backward cart extrusion has almost...

  15. Sagittal abdominal diameter shows better correlation with cardiovascular risk factors than waist circumference and BMI.

    Science.gov (United States)

    de Souza, Natalia Cavalheri; de Oliveira, Erick Prado

    2013-01-01

    Obesity (abdominal adiposity) is a risk factor for cardiovascular diseases and the most used methods to measure the adiposity are body mass index (BMI), waist circumference (WC), and sagittal abdominal diameter (SAD). To correlate BMI, WC, and SAD with biochemical parameters and blood pressure in adults. A non-experimental exploratory/descriptive and cross sectional study was developed and it was assessed 133 subjects (59 men and 74 women) aging between 18 and 87 years. It was registered the patients' weight (kg), height (m), BMI (kg/m(2)), WC (cm) and SAD (cm), and these parameters were correlated with glycemia, triglycerides, total cholesterol, HDL-c, LDL-c and blood pressure. After adjustment for gender and age, it was observed a positive correlation between SAD and systolic arterial blood pressure (r = 0.20), glycemia (r = 0.20), triglycerides (r = 0.32), LDL (r = 0.26), total cholesterol (TC) (r = 0.33), and a negative correlation with HDL-c (r = -0.21) (p correlation between WC and systolic arterial blood pressure (r = 0.14), triglycerides (r = 0.31), total cholesterol (r = 0.21), and a negative correlation with HDL-c (r = -0.24) (p correlation with systolic arterial blood pressure (r = 0.22), total cholesterol (r = 0.20), and triglycerides (r = 0.23) (p correlated with almost all the cardiovascular risk factors analyzed and it might be considered the best predictor of abdominal fat and cardiovascular risk.

  16. Quantum tunneling with friction

    Science.gov (United States)

    Tokieda, M.; Hagino, K.

    2017-05-01

    Using the phenomenological quantum friction models introduced by P. Caldirola [Nuovo Cimento 18, 393 (1941), 10.1007/BF02960144] and E. Kanai [Prog. Theor. Phys. 3, 440 (1948), 10.1143/ptp/3.4.440], M. D. Kostin [J. Chem. Phys. 57, 3589 (1972), 10.1063/1.1678812], and K. Albrecht [Phys. Lett. B 56, 127 (1975), 10.1016/0370-2693(75)90283-X], we study quantum tunneling of a one-dimensional potential in the presence of energy dissipation. To this end, we calculate the tunneling probability using a time-dependent wave-packet method. The friction reduces the tunneling probability. We show that the three models provide similar penetrabilities to each other, among which the Caldirola-Kanai model requires the least numerical effort. We also discuss the effect of energy dissipation on quantum tunneling in terms of barrier distributions.

  17. Investigation on frictional characteristic of deep-groove ball bearings subjected to radial loads

    Directory of Open Access Journals (Sweden)

    Yuchao Wang

    2015-07-01

    Full Text Available Radial load is of great significant influence on friction characteristic and fatigue life of rolling bearings. A frictional torque analysis was performed on the radially loaded SKF-6205 deep-groove ball bearings. The frictional torque formula was proposed as the sum of the frictional torques caused by elastic hysteresis, elastic hydrodynamic lubrication, differential slip, spinning friction of balls, friction between the balls and the cage pockets, and friction between the cages and the guiding lands. The experiments were carried out with the bearing with lubrication and the other one without lubrication under different radial loads and rotational speeds. In order to avoid the frictional torque measurement errors caused by the unequal length of arms, a positive–negative test method is employed to test bearing frictional torque. The experimental results showed that the frictional torque caused by radial loads played a leading role in all the frictional torque components of the bearing. Ultimately, a special theoretical model of frictional torque for deep-groove ball bearings was verified through comparing with the experimental results and SKF torque model. A reasonable correlation exists between the experiment results and the theoretical model.

  18. Solvent friction effects propagate over the entire protein molecule through low-frequency collective modes

    Energy Technology Data Exchange (ETDEWEB)

    Moritsugu, Kei [Yokohama City Univ., Yokohama (Japan); Kidera, Akinori [Yokohama City Univ., Yokohama (Japan); Smith, Jeremy C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-06-25

    Protein solvation dynamics has been investigated using atom-dependent Langevin friction coefficients derived directly from molecular dynamics (MD) simulations. To determine the effect of solvation on the atomic friction coefficients, solution and vacuum MD simulations were performed for lysozyme and staphylococcal nuclease and analyzed by Langevin mode analysis. The coefficients thus derived are roughly correlated with the atomic solvent-accessible surface area (ASA), as expected from the fact that friction occurs as the result of collisions with solvent molecules. However, a considerable number of atoms with higher friction coefficients are found inside the core region. Hence, the influence of solvent friction propagates into the protein core. The internal coefficients have large contributions from the low-frequency modes, yielding a simple picture of the surface-to-core long-range damping via solvation governed by collective low-frequency modes. To make use of these findings in implicit-solvent modeling, we compare the all-atom friction results with those obtained using Langevin dynamics (LD) with two empirical representations: the constant-friction and the ASA-dependent (Pastor Karplus) friction models. The constant-friction model overestimates the core and underestimates the surface damping whereas the ASA-dependent friction model, which damps protein atoms only on the solvent-accessible surface, reproduces well the friction coefficients for both the surface and core regions observed in the explicit-solvent MD simulations. Furthermore, in LD simulation, the solvent friction coefficients should be imposed only on the protein surface.

  19. Interfacial Friction and Adhesion of Polymer Brushes

    KAUST Repository

    Landherr, Lucas J. T.

    2011-08-02

    A bead-probe lateral force microscopy (LFM) technique is used to characterize the interfacial friction and adhesion properties of polymer brushes. Our measurements attempt to relate the physical structure and chemical characteristics of the brush to their properties as thin-film, tethered lubricants. Brushes are synthesized at several chain lengths and surface coverages from polymer chains of polydimethylsiloxane (PDMS), polystyrene (PS), and a poly(propylene glycol)-poly(ethylene glycol) block copolymer (PPG/PEG). At high surface coverage, PDMS brushes manifest friction coefficients (COFs) that are among the lowest recorded for a dry lubricant film (μ ≈ 0.0024) and close to 1 order of magnitude lower than the COF of a bare silicon surface. Brushes synthesized from higher molar mass chains exhibit higher friction forces than those created using lower molar mass polymers. Increased grafting density of chains in the brush significantly reduces the COF by creating a uniform surface of stretched chains with a decreased surface viscosity. Brushes with lower surface tension and interfacial shear stresses manifest the lowest COF. In particular, PDMS chains exhibit COFs lower than PS by a factor of 3.7 and lower than PPG/PEG by a factor of 4.7. A scaling analysis conducted on the surface coverage (δ) in relation to the fraction (ε) of the friction force developing from adhesion predicts a universal relation ε ∼ δ4/3, which is supported by our experimental data. © 2011 American Chemical Society.

  20. High Speed Ice Friction

    Science.gov (United States)

    Seymour-Pierce, Alexandra; Sammonds, Peter; Lishman, Ben

    2014-05-01

    Many different tribological experiments have been run to determine the frictional behaviour of ice at high speeds, ostensibly with the intention of applying results to everyday fields such as winter tyres and sports. However, experiments have only been conducted up to linear speeds of several metres a second, with few additional subject specific studies reaching speeds comparable to these applications. Experiments were conducted in the cold rooms of the Rock and Ice Physics Laboratory, UCL, on a custom built rotational tribometer based on previous literature designs. Preliminary results from experiments run at 2m/s for ice temperatures of 271 and 263K indicate that colder ice has a higher coefficient of friction, in accordance with the literature. These results will be presented, along with data from further experiments conducted at temperatures between 259-273K (in order to cover a wide range of the temperature dependent behaviour of ice) and speeds of 2-15m/s to produce a temperature-velocity-friction map for ice. The effect of temperature, speed and slider geometry on the deformation of ice will also be investigated. These speeds are approaching those exhibited by sports such as the luge (where athletes slide downhill on an icy track), placing the tribological work in context.

  1. FRICTION BUFFER STOP DESIGN

    Directory of Open Access Journals (Sweden)

    Petr Guziur

    2017-08-01

    Full Text Available Friction buffer stops are the favoured construction of buffer stop, mainly due to its high resistance and variety of layout. Last but not least is its manner of deceleration induced upon impact and during the braking what makes it smart solution in railway transport safety. The general approach of designing buffer stops is via usage of the kinetic energy and its conversion into work. Paper describes input parameters such as train velocity or buffer stop vicinity which is expressed by the safety coefficient implanted within the calculation. Furthermore, the paper shows the principle of calculation the friction buffer stop work, or to be more precise, the work of its braking jaws and optionally the work of additional braking jaws located behind the buffer stop. Last section of the paper is focused on the examples of designing friction buffer stops, points out the main complications and shows the charts of relation amongst braking distance, kinetic energy and braking force and the charts of relation between deceleration rate and braking distance.

  2. Linear Confirmatory Factor Models To Evaluate Multitrait-Multimethod Matrices: The Effects of Number of Indicators and Correlation among Methods.

    Science.gov (United States)

    Tomas, Jose M.; Hontangas, Pedro M.; Oliver, Amparo

    2000-01-01

    Assessed two models for confirmatory factor analysis of multitrait-multimethod data through Monte Carlo simulation. The correlated traits-correlated methods (CTCM) and the correlated traits-correlated uniqueness (CTCU) models were compared. Results suggest that CTCU is a good alternative to CTCM in the typical multitrait-multimethod matrix, but…

  3. Bioinspired orientation-dependent friction.

    Science.gov (United States)

    Xue, Longjian; Iturri, Jagoba; Kappl, Michael; Butt, Hans-Jürgen; del Campo, Aránzazu

    2014-09-23

    Spatular terminals on the toe pads of a gecko play an important role in directional adhesion and friction required for reversible attachment. Inspired by the toe pad design of a gecko, we study friction of polydimethylsiloxane (PDMS) micropillars terminated with asymmetric (spatular-shaped) overhangs. Friction forces in the direction of and against the spatular end were evaluated and compared to friction forces on symmetric T-shaped pillars and pillars without overhangs. The shape of friction curves and the values of friction forces on spatula-terminated pillars were orientation-dependent. Kinetic friction forces were enhanced when shearing against the spatular end, while static friction was stronger in the direction toward the spatular end. The overall friction force was higher in the direction against the spatula end. The maximum value was limited by the mechanical stability of the overhangs during shear. The aspect ratio of the pillar had a strong influence on the magnitude of the friction force, and its contribution surpassed and masked that of the spatular tip for aspect ratios of >2.

  4. Does spinal stenosis correlate with MRI findings and pain, psychologic factor and quality of life?

    Science.gov (United States)

    Lee, Mi Young; Jung, Sung Won; Lee, Su Yong

    2015-01-01

    Background To investigate and analyze MRI findings in relation to visual analogue scale (VAS), Oswestry Disability Index (ODI), psychological-factor, sleep-quality, and Short-Form Health Survey (SF-36) scores among patients with central lumbar spinal stenosis (LSS) for the purpose of elucidating a correlation. Methods From July 2013 to May 2014, 117 consecutive patients with central LSS were included in this study. All of the MRIs were evaluated by one of the authors, and the evaluated items were the dural sac cross-sectional area (DSCSA), the number of stenotic levels, and the presence and levels of spondylolisthesis. The ODI, VAS, 36-item SF-36, Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), and Pittsburgh Sleep Quality Index (PSQI) questionnaires were used to evaluate the participants. Results There are no correlations between the ODI, VAS, BDI, BAI, PSQI, and SF-36 scores and the minimum DSCSA; however, a significant correlation was found between the ODI scores and multilevel LSS. The BDI, BAI, and PSQI scores are higher for multilevel LSS compared with single-level LSS, but the difference of this mean value is not statistically significant. Conclusions A significant correlation was shown between those patients with multilevel LSS and the ODI scores; however, significant correlations were not found between the MRI findings and the psychological factors pertaining to sleep and life qualities. PMID:26495059

  5. Performance of prioritized activities is not correlated with functional factors after grip reconstruction in tetraplegia.

    Science.gov (United States)

    Wangdell, Johanna; Fridén, Jan

    2011-06-01

    To investigate the correlation between perceived performance in prioritized activities and physical conditions related to grip reconstruction. Retrospective clinical outcome study. Forty-seven individuals with tetraplegia were included in the study. Each participant underwent tendon transfer surgery in the hand between November 2002 and April 2009 and had a complete 1-year follow-up. Functional characteristics and performance data were collected from our database and medical records. Patients' perceived performances in prioritized activities were recorded using the Canadian Occupational Performance Measurement. Preoperative data included age at surgery, time since injury, severity of injury, sensibility and hand dominance. At 1-year follow-up, grip strength, key pinch strength, finger pulp-to-palm distance, distance between thumb and index finger and wrist flexion were measured. Correlation rank coefficient was used to test the possible relationship between physical data and activity performance. There were improvements in both functional factors and in rated performance of prioritized activities after surgery. There was no correlation between performance change and any of the physical functions, the factors known before surgery, or the functional outcome factors. No correlation exists between a single functional outcome parameter and the patients' perceived performance of their prioritized goals in reconstructive hand surgery in tetraplegia.

  6. Change in Frictional Behavior during Olivine Serpentinization

    Science.gov (United States)

    Xing, T.; Zhu, W.; French, M. E.; Belzer, B.

    2017-12-01

    Hydration of mantle peridotites (serpentinization) is pervasive at plate boundaries. It is widely accepted that serpentinization is intrinsically linked to hydromechanical processes within the sub-seafloor, where the interplay between cracking, fluid supply and chemical reactions is responsible for a spectrum of fault slip, from earthquake swarms at the transform faults, to slow slip events at the subduction zone. Previous studies demonstrate that serpentine minerals can either promote slip or creep depend on many factors that include sliding velocity, temperature, pressure, interstitial fluids, etc. One missing link from the experimental investigation of serpentine to observations of tectonic faults is the extent of alteration necessary for changing the frictional behaviors. We quantify changes in frictional behavior due to serpentinization by conducting experiments after in-situ serpentinization of olivine gouge. In the sample configuration a layer of powder is sandwiched between porous sandstone blocks with 35° saw-cut surface. The starting material of fine-grained (63 120 µm) olivine powder is reacted with deionized water for 72 hours at 150°C before loading starts. Under the conventional triaxial configuration, the sample is stressed until sliding occurs within the gouge. A series of velocity-steps is then performed to measure the response of friction coefficient to variations of sliding velocity from which the rate-and-state parameters are deduced. For comparison, we measured the frictional behavior of unaltered olivine and pure serpentine gouges.Our results confirm that serpentinization causes reduced frictional strength and velocity weakening. In unaltered olivine gouge, an increase in frictional resistance with increasing sliding velocity is observed, whereas the serpentinized olivine and serpentine gouges favor velocity weakening behaviors at the same conditions. Furthermore, we observed that high pore pressures cause velocity weakening in olivine but

  7. Correlation of Serum Insulin-like Growth Factor 1 with Prostate Cancer

    Directory of Open Access Journals (Sweden)

    Mohsen Ayati

    2012-10-01

    Full Text Available Background: Insulin-like growth factor-1 can act in both an autocrine and paracrine manner to promote normal growth and malignant cellular proliferation. The importance of this factor as a major regulatory peptide has been established for cells, in vitro and in vivo. However, the role of serum insulin-like growth factor-1 levels in the etiology of benign prostatic hyperplasia and prostate cancer has not received sufficient attention. The aim of this study was to determine the relationship between benign prostatic hyperplasia, prostate cancer, and serum insulin-like growth factor-1 levels.Methods: We collected blood samples from 68 individuals with prostate cancer (cases and 68 individuals with benign prostatic hyperplasia (controls who were patients at Imam Khomeini Hospital in Tehran, Iran. Those with benign prostatic hyperplasia had normal prostatic specific antigen levels 0.05. Mean serum insulin-like growth factor-1 levels were 219 ng/ml for the case group and 133 ng/ml for the control group, which was significant (P=0.0009. We did not observe any correlation between age and insulin-like growth factor-1 in the case group (P=0.83, r= -0.47, however there was a significant correlation in the control group (P=0.007, r=0.549. Although correlation between prostate volume and serum insulin-like growth factor-1 levels was not statistically significant in the case group (P=0.38, r=0.213, therewas a positive correlation observed in the control group (P<0.008, r=0.537.Conclusion: Our findings suggest that insulin-like growth factor-1 may have an etiologic role in prostate cancer. This interpretation is strengthened by the significant difference observed between serum insulin-like growth factor-1 levels in benign prostatic hyperplasia and prostate cancer patients. These results also offer additional opportunities for evaluating patients who have abnormal digital rectal exams or prostate specific antigen levels, yet their biopsies are normal. Under

  8. General solution of an exact correlation function factorization in conformal field theory

    International Nuclear Information System (INIS)

    Simmons, Jacob J H; Kleban, Peter

    2009-01-01

    The correlation function factorization with K a boundary operator product expansion coefficient, is known to hold for certain scaling operators at the two-dimensional percolation point and in a few other cases. Here the correlation functions are evaluated in the upper half-plane (or any conformally equivalent region) with x 1 and x 2 arbitrary points on the real axis, and z an arbitrary point in the interior. This type of result is of interest because it is both exact and universal, relates higher-order correlation functions to lower-order ones and has a simple interpretation in terms of cluster or loop probabilities in several statistical models. This motivated us to use the techniques of conformal field theory to determine the general conditions for its validity. Here, we discover that either (see display) factorizes in this way for any central charge c, generalizing previous results. In particular, the factorization holds for either FK (Fortuin–Kasteleyn) or spin clusters in the Q-state Potts models; it also applies to either the dense or dilute phases of the O(n) loop models. Further, only one other non-trivial set of highest-weight operators (in an irreducible Verma module) factorizes in this way. In this case the operators have negative dimension (for c<1) and do not seem to have a physical realization

  9. Correlates of a general psychopathology factor in a clinical sample of childhood sexual abuse survivors.

    Science.gov (United States)

    Hyland, Philip; Murphy, Jamie; Shevlin, Mark; Carey, Steven; Vallières, Frédérique; Murphy, David; Elklit, Ask

    2018-02-17

    Childhood sexual abuse (CSA) increases risk for most psychiatric disorders. There is evidence that the structure of psychopathology can be explained by a number of latent dimensions of psychopathology including a 'General Psychopathology' (P) factor. The objective of the current study was to provide the first assessment as to whether P is identifiable, and what its correlates might be in a clinical sample. An adult, clinical sample of Danish CSA survivors (N = 420) was assessed using the Millon Clinical Multiaxial Inventory-III. Confirmatory factory analysis (CFA) was used to assess the latent structure of nine psychiatric disorders, and structural equation modelling (SEM) was used to determine correlates of the best-fitting dimensional model. CFA results favoured a bifactor model including three specific dimensions of psychopathology, "Internalizing", "Externalizing", and "Thought Disorder", and a bi-factor "P". A SEM model that included ten predictors was a good fit to the data and explained 55% of variance in 'P'. The 'P' factor was significantly associated with emotional coping, negative self-worth, traumatic life events, and anxious attachments. Psychiatric disorders were assessed using self-report measures, and the sample was predominately female. Results provide initial evidence of P in a clinical sample and several unique correlates of this factor were identified. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Personality Correlates of Midlife Cardiometabolic Risk: The Explanatory Role of Higher-Order Factors of the Five-Factor Model.

    Science.gov (United States)

    Dermody, Sarah S; Wright, Aidan G C; Cheong, JeeWon; Miller, Karissa G; Muldoon, Matthew F; Flory, Janine D; Gianaros, Peter J; Marsland, Anna L; Manuck, Stephen B

    2016-12-01

    Varying associations are reported between Five-Factor Model (FFM) personality traits and cardiovascular disease risk. Here, we further examine dispositional correlates of cardiometabolic risk within a hierarchical model of personality that proposes higher-order traits of Stability (shared variance of Agreeableness, Conscientiousness, inverse Neuroticism) and Plasticity (Extraversion, Openness), and we test hypothesized mediation via biological and behavioral factors. In an observational study of 856 community volunteers aged 30-54 years (46% male, 86% Caucasian), latent variable FFM traits (using multiple-informant reports) and aggregated cardiometabolic risk (indicators: insulin resistance, dyslipidemia, blood pressure, adiposity) were estimated using confirmatory factor analysis (CFA). The cardiometabolic factor was regressed on each personality factor or higher-order trait. Cross-sectional indirect effects via systemic inflammation, cardiac autonomic control, and physical activity were tested. CFA models confirmed the Stability "meta-trait," but not Plasticity. Lower Stability was associated with heightened cardiometabolic risk. This association was accounted for by inflammation, autonomic function, and physical activity. Among FFM traits, only Openness was associated with risk over and above Stability, and, unlike Stability, this relationship was unexplained by the intervening variables. A Stability meta-trait covaries with midlife cardiometabolic risk, and this association is accounted for by three candidate biological and behavioral factors. © 2015 Wiley Periodicals, Inc.

  11. Experimental study of snow friction

    Science.gov (United States)

    Cohen, Caroline; Canale, Luca; Siria, Alessandro; Quere, David; Bocquet, Lyderic; Clanet, Christophe

    2017-11-01

    Snow friction results from the interplay of different physical processes: solid friction of granular material, phase change and lubrication, heat transport, capillarity, elasticity and plasticity. The multiple conditions of temperature, humidity and density of the snow result in different regimes of friction. In particular, there is an optimal amount of melted water to lubricate the contact between the ski sole and the snow grains. The thickness of the water layer depends on temperature, speed... A huge variety of waxes have been empirically developed to adapt the amount of water to the conditions of skiing, but remain mysterious. In these study, we investigate experimentally the mechanisms of snow friction at different scales: first, the friction of a ski on snow is measured on a test bench, depending on the snow characteristics and for different waxes. Then microscopic experiments are led in order to understand the friction at the ice crystals scale.

  12. Friction surfaced Stellite6 coatings

    Energy Technology Data Exchange (ETDEWEB)

    Rao, K. Prasad; Damodaram, R. [Department of Metallurgical and Materials Engineering - Indian Institute of Technology Madras, Chennai 600 036 (India); Rafi, H. Khalid, E-mail: khalidrafi@gmail.com [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Ram, G.D. Janaki [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Reddy, G. Madhusudhan [Metal Joining Group, Defence Metallurgical Research Laboratory (DMRL) Kanchanbagh, Hyderabad 500 058 (India); Nagalakshmi, R. [Welding Research Institute, Bharat Heavy Electricals Limited, Tiruchirappalli 620 014 (India)

    2012-08-15

    Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: Black-Right-Pointing-Pointer Stellite6 used as coating material for friction surfacing. Black-Right-Pointing-Pointer Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. Black-Right-Pointing-Pointer Finer and uniformly distributed carbides in friction surfaced coatings. Black-Right-Pointing-Pointer Absence of melting results compositional homogeneity in FS Stellite6 coatings.

  13. Friction surfaced Stellite6 coatings

    International Nuclear Information System (INIS)

    Rao, K. Prasad; Damodaram, R.; Rafi, H. Khalid; Ram, G.D. Janaki; Reddy, G. Madhusudhan; Nagalakshmi, R.

    2012-01-01

    Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: ► Stellite6 used as coating material for friction surfacing. ► Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. ► Finer and uniformly distributed carbides in friction surfaced coatings. ► Absence of melting results compositional homogeneity in FS Stellite6 coatings.

  14. Micromechanical study of macroscopic friction and dissipation in idealised granular materials: the effect of interparticle friction

    NARCIS (Netherlands)

    Kruyt, Nicolaas P.; Gutkowski, Witold; Rothenburg, L.; Kowalewski, Tomasz A.

    2004-01-01

    Using Discrete Element Method (DEM) simulations with varying interparticle friction coefficient, the relation between interparticle friction coefficient and macroscopic continuum friction and dissipation is investigated. As expected, macroscopic friction and dilatancy increase with interparticle

  15. Spatial factor analysis: a new tool for estimating joint species distributions and correlations in species range

    DEFF Research Database (Denmark)

    Thorson, James T.; Scheuerell, Mark D.; Shelton, Andrew O.

    2015-01-01

    1. Predicting and explaining the distribution and density of species is one of the oldest concerns in ecology. Species distributions can be estimated using geostatistical methods, which estimate a latent spatial variable explaining observed variation in densities, but geostatistical methods may...... be imprecise for species with low densities or few observations. Additionally, simple geostatistical methods fail to account for correlations in distribution among species and generally estimate such cross-correlations as a post hoc exercise. 2. We therefore present spatial factor analysis (SFA), a spatial...... model for estimating a low-rank approximation to multivariate data, and use it to jointly estimate the distribution of multiple species simultaneously. We also derive an analytic estimate of cross-correlations among species from SFA parameters. 3. As a first example, we show that distributions for 10...

  16. Investigations on the influence of the shape factor and friction in compression processes of cylindrical billets of AA 6082-T6 aluminum alloy by numerical and experimental techniques; Investigaciones sobre la influencia del factor de forma y del rozamiento en procesos de compresion de piezas cilindricas de aleacion de aluminio AA 6082-T6 mediante tecnicas numericas y experimentales

    Energy Technology Data Exchange (ETDEWEB)

    Marin, M. M.; Camacho, A. M.; Bernal, C.; Sebastian, M. A.

    2013-09-01

    The material characterization under similar load conditions to those applied during manufacturing is important in order to analyse Bulk Forming Compression Processes from a more realistic point of view. Open die forging of AA 6082-T6 aluminum alloy has been analysed by using experimental techniques and Finite Elements Method (FEM). The influence of the work piece geometry on the effects that friction produces in typical process variables such as applied forces, contact pressures and stresses and strains in work pieces has been analysed by FEM simulation. It has been shown that higher shape factors of the initial work piece geometry are recommended in such a way that friction effect is minimised. These results are interesting in order to decrease the required energy of the process and the tool wear, and could be used in further analysis of stamping processes. (Author)

  17. Friction and wear calculation methods

    CERN Document Server

    Kragelsky, I V; Kombalov, V S

    1981-01-01

    Friction and Wear: Calculation Methods provides an introduction to the main theories of a new branch of mechanics known as """"contact interaction of solids in relative motion."""" This branch is closely bound up with other sciences, especially physics and chemistry. The book analyzes the nature of friction and wear, and some theoretical relationships that link the characteristics of the processes and the properties of the contacting bodies essential for practical application of the theories in calculating friction forces and wear values. The effect of the environment on friction and wear is a

  18. Internal friction in enzyme reactions.

    Science.gov (United States)

    Rauscher, Anna; Derényi, Imre; Gráf, László; Málnási-Csizmadia, András

    2013-01-01

    The empirical concept of internal friction was introduced 20 years ago. This review summarizes the results of experimental and theoretical studies that help to uncover the nature of internal friction. After the history of the concept, we describe the experimental challenges in measuring and interpreting internal friction based on the viscosity dependence of enzyme reactions. We also present speculations about the structural background of this viscosity dependence. Finally, some models about the relationship between the energy landscape and internal friction are outlined. Alternative concepts regarding the viscosity dependence of enzyme reactions are also discussed. Copyright © 2012 International Union of Biochemistry and Molecular Biology, Inc.

  19. Sagittal abdominal diameter shows better correlation with cardiovascular risk factors than waist circumference and BMI

    OpenAIRE

    de Souza, Natalia Cavalheri; de Oliveira, Erick Prado

    2013-01-01

    Background Obesity (abdominal adiposity) is a risk factor for cardiovascular diseases and the most used methods to measure the adiposity are body mass index (BMI), waist circumference (WC), and sagittal abdominal diameter (SAD). Objective To correlate BMI, WC, and SAD with biochemical parameters and blood pressure in adults. Methods A non-experimental exploratory/descriptive and cross sectional study was developed and it was assessed 133 subjects (59 men and 74 women) aging between 18 and 87?...

  20. Shape Optimization in Contact Problems with Coulomb Friction and a Solution-Dependent Friction Coefficient

    Czech Academy of Sciences Publication Activity Database

    Beremlijski, P.; Outrata, Jiří; Haslinger, Jaroslav; Pathó, R.

    2014-01-01

    Roč. 52, č. 5 (2014), s. 3371-3400 ISSN 0363-0129 R&D Projects: GA ČR(CZ) GAP201/12/0671 Grant - others:GA MŠK(CZ) CZ.1.05/1.1.00/02.0070; GA MŠK(CZ) CZ.1.07/2.3.00/20.0070 Institutional support: RVO:67985556 ; RVO:68145535 Keywords : shape optimization * contact problems * Coulomb friction * solution-dependent coefficient of friction * mathematical programs with equilibrium constraints Subject RIV: BA - General Mathematics Impact factor: 1.463, year: 2014 http://library.utia.cas.cz/separaty/2014/MTR/outrata-0434234.pdf

  1. Correlation of ABO Blood Group Phenotype and Rhesus Factor with Periodontal Disease: An Observational Study.

    Science.gov (United States)

    Gautam, Anju; Mittal, Neelam; Singh, T B; Srivastava, Ruchi; Verma, Pushpendra Kumar

    2017-01-01

    The knowledge of the ABO blood group phenotype of the patients and their correlation with the periodontal disease maybe important in the development of early treatment strategies, and it would be helpful to target non-responding areas to periodontal therapy of the susceptible individuals. The present study was conducted to determine whether there was any correlation between periodontal diseases and ABO blood groups and Rh factor. This study was carried out on 537 subjects attending Faculty of Dental Sciences OPD in BHU. Subjects were divided into three groups: group I (healthy subjects), group II (subjects with gingivitis), and group III (subjects with periodontitis) based on periodontal examination (Gingival index, Bleeding Index, Probing pocket depth and clinical attachment level). ABO Blood grouping were done and correlated with the periodontal status of study subjects. Statistical Analysis: Data was analyzed using the statistical software namely Statistical Package for the Social Sciences (SPSS, Version 16, IBM Analytics) and Systat 8.0. In this study, there was a greater prevalence of gingivitis in blood group O and periodontitis in blood group B. The blood group AB showed the least prevalence of periodontal diseases. Similarly gingivitis and peridontitis were significantly higher among Rhesus positive groups when compared with Rhesus negative groups. Considering the results of this study, it can be concluded that ABO blood groups and Rh factor could be a risk factor for the development of periodontal disease.

  2. Dose-volume factors correlating with trismus following chemoradiation for head and neck cancer.

    Science.gov (United States)

    Rao, Shyam D; Saleh, Ziad H; Setton, Jeremy; Tam, Moses; McBride, Sean M; Riaz, Nadeem; Deasy, Joseph O; Lee, Nancy Y

    2016-01-01

    To investigate the dose-volume factors in mastication muscles that are implicated as possible causes of trismus in patients following treatment with intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy for head and neck cancers. All evaluable patients treated at our institution between January 2004 and April 2009 with chemotherapy and IMRT for squamous cell cancers of the oropharynx, nasopharynx, hypopharynx or larynx were included in this analysis (N = 421). Trismus was assessed using CTCAE 4.0. Bi-lateral masseter, temporalis, lateral pterygoid and medial pterygoid muscles were delineated on axial computed tomography (CT) treatment planning images, and dose-volume parameters were extracted to investigate univariate and multimetric correlations. Forty-six patients (10.9%) were observed to have chronic trismus of grade 1 or greater. From analysis of baseline patient characteristics, toxicity correlated with primary site and patient age. From dose-volume analysis, the steepest dose thresholds and highest correlations were seen for mean dose to ipsilateral masseter (Spearman's rank correlation coefficient Rs = 0.25) and medial pterygoid (Rs = 0.23) muscles. Lyman-Kutcher-Burman modeling showed highest correlations for the same muscles. The best correlation for multimetric logistic regression modeling was with V68Gy to the ipsilateral medial pterygoid (Rs = 0.29). Chemoradiation-induced trismus remains a problem particularly for patients with oropharyngeal carcinoma. Strong dose-volume correlations support the hypothesis that limiting dose to the ipsilateral masseter muscle and, in particular, the medial pterygoid muscle may reduce the likelihood of trismus.

  3. Understanding Friction Stir Welding

    Science.gov (United States)

    Nunes, A. C., Jr.

    2018-01-01

    This Technical Memorandum explains the friction stir welding process in terms of two basic concepts: the concentration of deformation in a shear surface enveloping the tool and the composition of the overall plastic flow field around the tool from simple flow field components. It is demonstrated how weld structure may be understood and torque, drag, and lateral tool forces may be estimated using these concepts. Some discrepancies between computations and accompanying empirical data are discussed in the text. This work is intended to be helpful to engineers in diagnosing problems and advancing technology.

  4. Brachistochrone with Coulomb friction

    Science.gov (United States)

    Hayen, J.

    2005-10-01

    The classical brachistochrone is considered with the inclusion of a resistant force, which is due to Coulomb friction, in addition to the uniform gravitational force that is present. The solution to this problem is expressed in terms of standard functions, and it is developed in two separate ways by means of constrained variational calculus methods. These ways involve formulations of the problem in terms of temporal and spatial independent variables, respectively. The equations of motion that result in both cases are non-linear and coupled. The utilization of path variables is a central feature of the developments provided.

  5. Frictional behaviour of high performance fibrous tows: Friction experiments

    NARCIS (Netherlands)

    Cornelissen, Bo; Rietman, Bert; Akkerman, Remko

    2013-01-01

    Tow friction is an important mechanism in the production and processing of high performance fibrous tows. The frictional behaviour of these tows is anisotropic due to the texture of the filaments as well as the tows. This work describes capstan experiments that were performed to measure the

  6. Friction analysis of kinetic schemes : the friction coefficient

    NARCIS (Netherlands)

    Lolkema, Juke S.

    1995-01-01

    Friction analysis is proposed as the application of general control analysis to single enzymes to describe the control of elementary kinetic steps on the overall catalytic rate. For each transition, a friction coefficient is defined that measures the sensitivity of the turnover rate to the free

  7. General theory of frictional heating with application to rubber friction

    Science.gov (United States)

    Fortunato, G.; Ciaravola, V.; Furno, A.; Lorenz, B.; Persson, B. N. J.

    2015-05-01

    The energy dissipation in the contact regions between solids in sliding contact can result in high local temperatures which may strongly effect friction and wear. This is the case for rubber sliding on road surfaces at speeds above 1 mm s-1. We derive equations which describe the frictional heating for solids with arbitrary thermal properties. The theory is applied to rubber friction on road surfaces and we take into account that the frictional energy is partly produced inside the rubber due to the internal friction of rubber and in a thin (nanometer) interfacial layer at the rubber-road contact region. The heat transfer between the rubber and the road surface is described by a heat transfer coefficient which depends on the sliding speed. Numerical results are presented and compared to experimental data. We find that frictional heating results in a kinetic friction force which depends on the orientation of the sliding block, thus violating one of the two basic Leonardo da Vinci ‘laws’ of friction.

  8. Friction torque in thrust ball bearings grease lubricated

    Science.gov (United States)

    Ianuş, G.; Dumitraşcu, A. C.; Cârlescu, V.; Olaru, D. N.

    2016-08-01

    The authors investigated experimentally and theoretically the friction torque in a modified thrust ball bearing having only 3 balls operating at low axial load and lubricated with NGLI-00 and NGLI-2 greases. The experiments were made by using spin-down methodology and the results were compared with the theoretical values based on Biboulet&Houpert's rolling friction equations. Also, the results were compared with the theoretical values obtained with SKF friction model adapted for 3 balls. A very good correlation between experiments and Biboulet_&_Houpert's predicted results was obtained for the two greases. Also was observed that the theoretical values for the friction torque calculated with SKF model adapted for a thrust ball bearing having only 3 balls are smaller that the experimental values.

  9. Effects of different ligature materials on friction in sliding mechanics.

    Science.gov (United States)

    Khamatkar, Aparna; Sonawane, Sushma; Narkhade, Sameer; Gadhiya, Nitin; Bagade, Abhijit; Soni, Vivek; Betigiri, Asha

    2015-05-01

    During orthodontic tooth movement friction occurs at the bracket wire interface. Out of the total force applied to the tooth movement, some of it is dissipated as friction, and the remainder is transferred to the supporting structures of the tooth to mediate tooth movement. However many factors affect friction, and method of arch wire ligation being an important contributing factor. Hence, this study was carried out to evaluate the effects of different ligature materials on friction in sliding mechanics and to compare the effect of environment (dry and wet) on friction produced in sliding mechanics. The evaluation of friction between the bracket and the archwire consisted of a simulated half arch fixed appliance with archwire ligated in a vertical position. Four 0.022" maxillary stainless steel premolar brackets having a - 0° torque and 0° angulation were aligned with a 0.019" × 0.025" stainless steel arch wire onto a rigid Plexiglass sheet. The movable test bracket was fitted with a 10 mm long, 0.045" thick stainless steel power arm on the bonding surface. Testing was performed on a Hounsfield material testing machine. A total of 100 g weight was suspended from the power arm and the load needed to move the bracket over the distance of not material and environment significantly affected the degree of friction generated during sliding mechanics. Teflon coated stainless steel ligatures produced the least friction among the materials tested in both dry and wet conditions and there was no significant effect on friction in this group caused due to lubrication.

  10. On the friction coefficient of straight-chain aggregates.

    Science.gov (United States)

    Isella, Lorenzo; Drossinos, Yannis

    2011-04-15

    A methodology to calculate the friction coefficient of an aggregate in the continuum regime is proposed. The friction coefficient and the monomer shielding factors, aggregate-average or individual, are related to the molecule-aggregate collision rate that is obtained from the molecular diffusion equation with an absorbing boundary condition on the aggregate surface. Calculated friction coefficients of straight chains are in very good agreement with previous results, suggesting that the friction coefficients may be accurately calculated from the product of the collision rate and an average momentum transfer, the latter being independent of aggregate morphology. Langevin-dynamics simulations show that the diffusive motion of straight-chain aggregates may be described either by a monomer-dependent or an aggregate-average random force, if the shielding factors are appropriately chosen. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Shape optimization in 2D contact problems with given friction and a solution-dependent coefficient of friction

    Czech Academy of Sciences Publication Activity Database

    Haslinger, J.; Outrata, Jiří; Pathó, R.

    2012-01-01

    Roč. 20, č. 1 (2012), s. 31-59 ISSN 1877-0533 R&D Projects: GA AV ČR IAA100750802 Institutional research plan: CEZ:AV0Z10750506 Institutional support: RVO:67985556 Keywords : shape optimization * Signorini problem * model with given frinction * solution-dependent coefficient of friction * mathematical probrams with equilibrium constraints Subject RIV: BA - General Mathematics Impact factor: 1.036, year: 2012 http://library.utia.cas.cz/separaty/2012/MTR/outrata-shape optimization in 2d contact problems with given friction and a solution-dependent coefficient of friction .pdf

  12. Selected factors correlated to athletic performance in adults with mental retardation.

    Science.gov (United States)

    Franciosi, Emanuele; Baldari, Carlo; Gallotta, Maria Chiara; Emerenziani, Gian Pietro; Guidetti, Laura

    2010-04-01

    The aims of this study were to assess the contribution of selected factors to the athletic performance in adults with mental retardation (MR) and to analyze the correlation of each factor with subjects' MR levels. Twenty-nine trained athletes with MR aged 20-45 years were recruited. The fundamental factors included anthropometric measurements, flexibility, muscular strength and endurance, explosive leg power, cardiovascular endurance, and motor coordination. The athletic performances were as follows: 60 m, 300 m, 400 m in walking, standing long jump, and vortex throw (Level I) or 100-m run, shot put, and long jump (Level II). Motor coordination and body weight had significant contributions to 60 m (p jump (p shot put (p jump (p < 0.05). MR level was positively correlated to motor coordination (p < 0.05) and negatively to abdominal muscular strength and endurance (p < 0.05). In conclusion, the results showed the possibility to determine the contributions of selected factors to the athletic performance. This should be addressed in athletics training to help athletes with MR to perform successfully in their competitions.

  13. Friction Stir Welding

    Science.gov (United States)

    Nunes, Arthur C., Jr.

    2008-01-01

    Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and promises to be an important welding process for any industries where welds of optimal quality are demanded. This article provides an introduction to the FSW process. The chief concern is the physical effect of the tool on the weld metal: how weld seam bonding takes place, what kind of weld structure is generated, potential problems, possible defects for example, and implications for process parameters and tool design. Weld properties are determined by structure, and the structure of friction stir welds is determined by the weld metal flow field in the vicinity of the weld tool. Metal flow in the vicinity of the weld tool is explained through a simple kinematic flow model that decomposes the flow field into three basic component flows: a uniform translation, a rotating solid cylinder, and a ring vortex encircling the tool. The flow components, superposed to construct the flow model, can be related to particular aspects of weld process parameters and tool design; they provide a bridge to an understanding of a complex-at-first-glance weld structure. Torques and forces are also discussed. Some simple mathematical models of structural aspects, torques, and forces are included.

  14. Subjective symptoms of carpal tunnel syndrome correlate more with psychological factors than electrophysiological severity.

    Science.gov (United States)

    Khan, Firosh; Shehna, Abdulkhader; Ramesh, Sivaramakrishnan; Sandhya, Kakkassery Sankaran; Paul, Reji

    2017-01-01

    Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy and is one of the most common requests for electrodiagnosis. We aimed to note the relationship of subjective symptom severity of CTS, with objective electrophysiological severity and psychological status of patients. One hundred and forty-four consecutive patients of CTS referred to neurophysiology laboratory of a tertiary care hospital over 1 year were prospectively studied. Boston CTS Assessment Questionnaire (BCTSAQ) and visual analog scale (VAS) were used to assess subjective symptom severity. Psychological status was assessed by Hospital Anxiety and Depression Scale (HADS). Electrophysiological severity of CTS was estimated by median motor distal latency and median to ulnar peak sensory latency difference across the wrist. Each parameter in both hands was scored from 0 to 3 depending on the severity grade, and a composite electrophysiological severity score (CEPSS) was calculated for each patient by summing up the scores in both hands. Statistical analysis was done by Spearman's rank correlation test. There was significant correlation of BCTSAQ with VAS ( P = 0.001), HADS anxiety score ( P < 0.001), and HADS depression score ( P = 0.01). CEPSS had no significant correlation with VAS ( P = 0.103), HADS anxiety score ( P = 0.211), or HADS depression score ( P = 0.55). CEPSS had a borderline correlation with BCTSAQ ( P = 0.048). While the subjective symptoms of CTS are well correlated with psychological factors, their correlation with objective electrophysiological severity is weak. Hence, prompt treatment of psychological comorbidity is important in symptomatic management of CTS; decision about surgical intervention should be based on electrophysiological severity rather than symptom severity.

  15. Factors related to academic success among nursing students: a descriptive correlational research study.

    Science.gov (United States)

    Beauvais, Audrey M; Stewart, Julie G; DeNisco, Susan; Beauvais, John E

    2014-06-01

    The current rise in employment is improving forecasts for the future supply of registered nurses; however sizeable shortages are still projected. With the intention of improving academic success in nursing students, related factors need to be better understood. The purpose of the correlational study was to describe the relationship between emotional intelligence, psychological empowerment, resilience, spiritual well-being, and academic success in undergraduate and graduate nursing students. A descriptive correlational design was utilized. The study was set in a private Catholic university. There were 124 participants. There were 59% undergraduate and 41% graduate students. Background data, in addition to the Spreitzer Psychological Empowerment Scale, the Wagnild and Young Resilience Scale, and the Spiritual Well-Being Scale and the Mayer-Salovey-Caruso Emotional Intelligence Test, was collected from students who met study criteria. In a combined sample, academic success was correlated with overall spiritual well-being, empowerment and resilience. Although academic success was not correlated with overall emotional intelligence, it was correlated with the emotional intelligence branch four (managing emotions) score. When undergraduate and graduate students were considered separately, only one correlation was found to be significantly related to academic success in the undergraduate sample, namely, emotional intelligence branch one (perceiving emotions). When examining the data from just graduate level nurses, significant relationships were found between total emotional intelligence with academic success, resilience with academic success, and psychological empowerment with academic success. The significant relationship between psychological empowerment, resilience, spiritual well-being and academic success in this study supports the statements in the literature that these concepts may play an important role in persistence through the challenges of nursing education

  16. Subjective symptoms of carpal tunnel syndrome correlate more with psychological factors than electrophysiological severity

    Directory of Open Access Journals (Sweden)

    Firosh Khan

    2017-01-01

    Full Text Available Aim: Carpal tunnel syndrome (CTS is the most common entrapment neuropathy and is one of the most common requests for electrodiagnosis. We aimed to note the relationship of subjective symptom severity of CTS, with objective electrophysiological severity and psychological status of patients. Patients and Methods: One hundred and forty-four consecutive patients of CTS referred to neurophysiology laboratory of a tertiary care hospital over 1 year were prospectively studied. Boston CTS Assessment Questionnaire (BCTSAQ and visual analog scale (VAS were used to assess subjective symptom severity. Psychological status was assessed by Hospital Anxiety and Depression Scale (HADS. Electrophysiological severity of CTS was estimated by median motor distal latency and median to ulnar peak sensory latency difference across the wrist. Each parameter in both hands was scored from 0 to 3 depending on the severity grade, and a composite electrophysiological severity score (CEPSS was calculated for each patient by summing up the scores in both hands. Statistical analysis was done by Spearman's rank correlation test. Results: There was significant correlation of BCTSAQ with VAS (P = 0.001, HADS anxiety score (P < 0.001, and HADS depression score (P = 0.01. CEPSS had no significant correlation with VAS (P = 0.103, HADS anxiety score (P = 0.211, or HADS depression score (P = 0.55. CEPSS had a borderline correlation with BCTSAQ (P = 0.048. Conclusions: While the subjective symptoms of CTS are well correlated with psychological factors, their correlation with objective electrophysiological severity is weak. Hence, prompt treatment of psychological comorbidity is important in symptomatic management of CTS; decision about surgical intervention should be based on electrophysiological severity rather than symptom severity.

  17. Investment Frictions and the Relative Price of Investment Goods in an Open Economy Model

    OpenAIRE

    Parantap Basu; Christoph Thoenissen

    2007-01-01

    Is the relative price of investment goods a good proxy for investment frictions? We analyze investment frictions in an open economy, flexible price, two-country model and show that when the relative price of investment goods is endogenously determined in such a model, the relative price of investment can actually rise in response to a reduction in investment frictions. Only when the model is driven by TFP shocks do we observe a data congruent negative correlation between investment and the re...

  18. Internal frictions of austenitic stainless steels at low temperature

    Science.gov (United States)

    Tsubono, K.; Owa, S.; Mio, N.; Akasaka, N.; Hirakawa, H.

    Internal frictions were measured for three types of austenitic stainless steel, AISI 304, 310S and 316, in the temperature range 4-300 K. The intrinsic friction is presented in terms of the quality factor of a 20 kHz eigenmode vibration of discs made from each material. Temperature dependence is also given for the resonant frequency of each disc. These mechanical properties show some peculiarities at low temperature.

  19. Risk factors and correlates of deliberate self-harm behavior: a systematic review.

    Science.gov (United States)

    Fliege, Herbert; Lee, Jeong-Ran; Grimm, Anne; Klapp, Burghard F

    2009-06-01

    Deliberate self-harm behavior--without suicidal intent--is a serious health problem and may be studied as a clinical phenomenon in its own right. Empirical studies of sociodemographic and psychological correlates and risk factors are systematically reviewed. We searched Medline, PsycINFO, PSYNDEX (German psychological literature), and reference lists. We targeted self-induced bodily harm without conscious suicidal intent. Studies on suicidal behavior or self-poisoning were only included if they also assessed nonsuicidal self-harm. Fifty-nine original studies met the criteria. Deliberate self-harm may occur at all ages, yet adolescents and young adults are at a higher risk. Evidence on gender is complex. Only 5 studies realize a prospective design (6 months to 10 years) and test predictors. The majority use cross-sectional and retrospective methods. No longitudinal study (separately) examines new incidence. Evidence of correlates encompasses distal/proximal, person/environment, and state/trait factors. Many studies report associations between current self-harm behavior and a history of childhood sexual abuse. Adolescent and adult self-harmers experience more frequent and more negative emotions, such as anxiety, depression, and aggressiveness, than persons who do not self-harm. Two studies yield specific interactions between childhood trauma and current traits and states such as low emotional expressivity, low self-esteem, and dissociation with respect to a vulnerability to self-harm. Evidence of distal, biographical stressors is fairly strong. Proximal stressors have rarely been investigated; protective factors, hardly at all. Despite many findings of correlates, the data do not yet justify terming them risk factors. Longitudinal studies are needed.

  20. Correlation between the state of periodontal tissues and selected risk factors for periodontitis and myocardial infarction.

    Science.gov (United States)

    Górska, Renata; Dembowska, Elżbieta; Konopka, Tomasz P; Wysokińska-Miszczuk, Joanna; Pietruska, Małgorzata; Ganowicz, Ewa

    2017-01-01

    The current level of knowledge indicates a relationship between periodontitis and diabetes and/or cardiovascular diseases (CVD). Periodontitis can be not only a risk factor for these diseases, but also a condition modifying other primary risk factors associated with the occurrence of cardiovascular complications (lipid disorders, arterial hypertension, etc.) or diabetes. The aim of the study was an analysis of the correlation between the state of periodontal tissues and selected risk factors for myocardial infarction (MI) in patients after recent myocardial infarction. The study included 417 patients (92 women, 325 men) hospitalized due to recent MI. The inclusion criteria were MI history and age below 70 years. The state of periodontal tissues (plaque index, bleeding on probing, pocket depth and clinical attachment loss, CPI index) and selected risk factors for periodontitis and CVD were recorded. An analysis of the results showed no statistically significant correlation between the depth, the number, percentage of periodontal pockets and the average clinical attachment level on one hand and BMI on the other hand. Whereas a statistically significant correlation was observed between tobacco smoking and the degree of severity of periodontal diseases measured by the average pocket depth, the number and percentage of pockets above 4 mm and the average clinical attachment loss, as well as between hypertension and the state of oral hygiene and between diabetes and the number of preserved teeth and the number of pockets above 4 mm. The degree of severity of periodontal disease can impact hypertension and diabetes, which could potentially influence the occurrence and course of CVD.

  1. Entry cost, financial friction, and cross-country differences in income and TFP

    OpenAIRE

    Lei Fang

    2010-01-01

    This paper develops a model to assess the quantitative effect of entry cost and financial friction on cross-country income and total factor productivity (TFP) differences. The main focus is on the interaction between entry cost and financial friction. The model is calibrated to match establishment-level statistics for the U.S. economy assuming a perfect financial market. The quantitative analysis shows that entry costs and financial frictions together can generate a factor ten of the differen...

  2. Friction Testing of Thermoplastic Composites

    NARCIS (Netherlands)

    Sachs, Ulrich; Haanappel, Sebastiaan; Rietman, Bert; Akkerman, Remko; Erath, Mark A.

    2011-01-01

    Friction phenomena play a major role in thermoplastic composite forming processes. In order to make use of the large potential these materials have, accurate CAE tools are needed that as a consequence incorporate temperature, pressure and velocity dependent friction behavior. To obtain a sound

  3. Friction of atomically stepped surfaces

    NARCIS (Netherlands)

    Dikken, R.J.; Thijsse, B.J.; Nicola, L.

    2017-01-01

    The friction behavior of atomically stepped metal surfaces under contact loading is studied using molecular dynamics simulations. While real rough metal surfaces involve roughness at multiple length scales, the focus of this paper is on understanding friction of the smallest scale of roughness:

  4. Blades Couple Dry Friction Connection

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk; Radolfová, Alena

    2015-01-01

    Roč. 9, č. 1 (2015), s. 31-40 ISSN 1802-680X Institutional support: RVO:61388998 Keywords : stick-slip dry friction * 3D friction characteristic * tangential contact stiffness * hysterezis loop * response curves Subject RIV: BI - Acoustics

  5. Auto-correlation of journal impact factor for consensus research reporting statements: a cohort study.

    Science.gov (United States)

    Shanahan, Daniel R

    2016-01-01

    Background. The Journal Citation Reports journal impact factors (JIFs) are widely used to rank and evaluate journals, standing as a proxy for the relative importance of a journal within its field. However, numerous criticisms have been made of use of a JIF to evaluate importance. This problem is exacerbated when the use of JIFs is extended to evaluate not only the journals, but the papers therein. The purpose of this study was therefore to investigate the relationship between the number of citations and journal IF for identical articles published simultaneously in multiple journals. Methods. Eligible articles were consensus research reporting statements listed on the EQUATOR Network website that were published simultaneously in three or more journals. The correlation between the citation count for each article and the median journal JIF over the published period, and between the citation count and number of article accesses was calculated for each reporting statement. Results. Nine research reporting statements were included in this analysis, representing 85 articles published across 58 journals in biomedicine. The number of citations was strongly correlated to the JIF for six of the nine reporting guidelines, with moderate correlation shown for the remaining three guidelines (median r = 0.66, 95% CI [0.45-0.90]). There was also a strong positive correlation between the number of citations and the number of article accesses (median r = 0.71, 95% CI [0.5-0.8]), although the number of data points for this analysis were limited. When adjusted for the individual reporting guidelines, each logarithm unit of JIF predicted a median increase of 0.8 logarithm units of citation counts (95% CI [-0.4-5.2]), and each logarithm unit of article accesses predicted a median increase of 0.1 logarithm units of citation counts (95% CI [-0.9-1.4]). This model explained 26% of the variance in citations (median adjusted r (2) = 0.26, range 0.18-1.0). Conclusion. The impact factor of the

  6. Auto-correlation of journal impact factor for consensus research reporting statements: a cohort study

    Directory of Open Access Journals (Sweden)

    Daniel R. Shanahan

    2016-03-01

    Full Text Available Background. The Journal Citation Reports journal impact factors (JIFs are widely used to rank and evaluate journals, standing as a proxy for the relative importance of a journal within its field. However, numerous criticisms have been made of use of a JIF to evaluate importance. This problem is exacerbated when the use of JIFs is extended to evaluate not only the journals, but the papers therein. The purpose of this study was therefore to investigate the relationship between the number of citations and journal IF for identical articles published simultaneously in multiple journals. Methods. Eligible articles were consensus research reporting statements listed on the EQUATOR Network website that were published simultaneously in three or more journals. The correlation between the citation count for each article and the median journal JIF over the published period, and between the citation count and number of article accesses was calculated for each reporting statement. Results. Nine research reporting statements were included in this analysis, representing 85 articles published across 58 journals in biomedicine. The number of citations was strongly correlated to the JIF for six of the nine reporting guidelines, with moderate correlation shown for the remaining three guidelines (median r = 0.66, 95% CI [0.45–0.90]. There was also a strong positive correlation between the number of citations and the number of article accesses (median r = 0.71, 95% CI [0.5–0.8], although the number of data points for this analysis were limited. When adjusted for the individual reporting guidelines, each logarithm unit of JIF predicted a median increase of 0.8 logarithm units of citation counts (95% CI [−0.4–5.2], and each logarithm unit of article accesses predicted a median increase of 0.1 logarithm units of citation counts (95% CI [−0.9–1.4]. This model explained 26% of the variance in citations (median adjusted r2 = 0.26, range 0.18–1.0. Conclusion

  7. Correlation of maternal factors and hemoglobin concentration during pregnancy Shiraz 2006

    Directory of Open Access Journals (Sweden)

    Marzieh Akbarzadeh

    2009-12-01

    Full Text Available Background: Anemia in pregnancy is a serious condition, contributing to maternal mortality, morbidity and fetal morbidity and its prevalence varies between 35-100% in developing countries. This investigation is conducted to survey the correlation of maternal factors and the changes in hemoglobin in pregnant women. Method: In this study, 108 healthy pregnant women with gestational age of 10 to 14 weeks, chosen by cluster random sampling were included. The women were followed in three visits: at the end of the first, second and third trimester. In addition, correlation of Hb concentration with maternal factors including BMI, age parity, hyperemesis, gestational age, pregnancy interval and weight gain was investigated. Results: There was no significant correlation between BMI, parity, pregnancy interval, severe nausea and vomiting and also maternal age with hemoglobin level during pregnancy. Moreover, Multiple regression models showed that adequate maternal weight gain (P<0.009 and high hemoglobin (p<0.0001 in the first trimester were positive predictors and late iron supplementation was negative predictor of hemoglobin in pregnancy (P<0.006. Conclusion: Our data demonstrated that adequate maternal weight gain, high hemoglobin in the first trimester and also late iron supplementation could be as predictors in clinical settings in this query.

  8. Television Time among Brazilian Adolescents: Correlated Factors are Different between Boys and Girls

    Directory of Open Access Journals (Sweden)

    Diego Augusto Santos Silva

    2014-01-01

    Full Text Available Objective. The aim of this study was to identify the prevalence of excess television time and verify correlated factors in adolescent males and females. Methods. This cross-sectional study included 2,105 adolescents aged from 13 to 18 years from the city of Aracaju, Northeastern Brazil. Television time was self-reported, corresponding to the time spent watching television in a typical week. Several correlates were examined including age, skin color, socioeconomic status, parent education, physical activity level, consumption of fruits and vegetables, smoking status, alcohol use, and sports team participation. Results. The prevalence excess television time (≥2 hours/day in girls and boys was 70.9% and 66.2%, respectively. Girls with low socioeconomic status or inadequate consumption of fruits and vegetables were more likely to have excess television time. Among boys, those >16 years of age or with black skin color were more likely to have excess television time. Conclusions. Excess television time was observed in more than two-thirds of adolescents, being more evident in girls. Correlated factors differed according to sex. Efforts to reduce television time among Brazilian adolescents, and replace with more active pursuits, may yield desirable public health benefits.

  9. Socio-economic factors of bacillary dysentery based on spatial correlation analysis in Guangxi Province, China.

    Directory of Open Access Journals (Sweden)

    Chengjing Nie

    Full Text Available BACKGROUND: In the past decade, bacillary dysentery was still a big public health problem in China, especially in Guangxi Province, where thousands of severe diarrhea cases occur every year. METHODS: Reported bacillary dysentery cases in Guangxi Province were obtained from local Centers for Diseases Prevention and Control. The 14 socio-economic indexes were selected as potential explanatory variables for the study. The spatial correlation analysis was used to explore the associations between the selected factors and bacillary dysentery incidence at county level, which was based on the software of ArcGIS10.2 and GeoDA 0.9.5i. RESULTS: The proportion of primary industry, the proportion of younger than 5-year-old children in total population, the number of hospitals per thousand persons and the rates of bacillary dysentery incidence show statistically significant positive correlation. But the proportion of secondary industry, per capital GDP, per capital government revenue, rural population proportion, popularization rate of tap water in rural area, access rate to the sanitation toilets in rural, number of beds in hospitals per thousand persons, medical and technical personnel per thousand persons and the rate of bacillary dysentery incidence show statistically significant negative correlation. The socio-economic factors can be divided into four aspects, including economic development, health development, medical development and human own condition. The four aspects were not isolated from each other, but interacted with each other.

  10. Television time among Brazilian adolescents: correlated factors are different between boys and girls.

    Science.gov (United States)

    Silva, Diego Augusto Santos; Tremblay, Mark Stephen; Gonçalves, Eliane Cristina de Andrade; Silva, Roberto Jerônimo dos Santos

    2014-01-01

    The aim of this study was to identify the prevalence of excess television time and verify correlated factors in adolescent males and females. This cross-sectional study included 2,105 adolescents aged from 13 to 18 years from the city of Aracaju, Northeastern Brazil. Television time was self-reported, corresponding to the time spent watching television in a typical week. Several correlates were examined including age, skin color, socioeconomic status, parent education, physical activity level, consumption of fruits and vegetables, smoking status, alcohol use, and sports team participation. The prevalence excess television time (≥ 2 hours/day) in girls and boys was 70.9% and 66.2%, respectively. Girls with low socioeconomic status or inadequate consumption of fruits and vegetables were more likely to have excess television time. Among boys, those >16 years of age or with black skin color were more likely to have excess television time. Excess television time was observed in more than two-thirds of adolescents, being more evident in girls. Correlated factors differed according to sex. Efforts to reduce television time among Brazilian adolescents, and replace with more active pursuits, may yield desirable public health benefits.

  11. A study on a characteristic of stem friction coefficient for motor operated flexible wedge gate valve

    International Nuclear Information System (INIS)

    Kim, Dae-Woong; Park, Sung-Geun; Lee, Sang-Guk; Kang, Shin-Cheul

    2009-01-01

    Stem friction coefficient is a coefficient that represents friction between thread leads of the stem and stem nut. It is an important factor to determine output thrust delivered from the actuator to the valve stem in assessing performance of motor operated valves. This study analyzes the effects of changes in differential pressure on stem friction coefficient, and determines the bounding value of stem friction coefficient. A dynamic test was conducted on multiple flexible wedge gate valves in various differential pressure conditions, and the test data was statistically analyzed to determine the bounding value. The results show that stem friction coefficient in middle and high differential pressure is influenced by fluid pressure, while stem friction coefficient in low differential pressure is almost not affected by fluid pressure. In addition, it is found that the bounding value of stem friction coefficient is higher in a closing stroke than in an opening stroke.

  12. Overlap Between the General Factor of Personality and Trait Emotional Intelligence: A Genetic Correlation Study.

    Science.gov (United States)

    van der Linden, Dimitri; Schermer, Julie A; de Zeeuw, Eveline; Dunkel, Curtis S; Pekaar, Keri A; Bakker, Arnold B; Vernon, Philip A; Petrides, K V

    2018-03-01

    A previous meta-analysis (Van der Linden et al., Psychol Bull 143:36-52, 2017) showed that the General Factor of Personality (GFP) overlaps with ability as well as trait emotional intelligence (EI). The correlation between trait EI and the GFP was so high (ρ = 0.88) in that meta-analysis that these two may be considered virtually identical constructs. The present study builds on these findings by examining whether the strong phenotypic correlation between the GFP and trait EI has a genetic component. In a sample of monozygotic and dizygotic twins, the heritability estimates for the GFP and trait EI were 53 and 45%, respectively. Moreover, there was a strong genetic correlation of r = .90 between the GFP and trait EI. Additional analyses suggested that a substantial proportion of the genetic correlations reflects non-additive genetic effects (e.g., dominance and epistasis). These findings are discussed in light of evolutionary accounts of the GFP.

  13. Nanoscale friction and wear maps.

    Science.gov (United States)

    Tambe, Nikhil S; Bhushan, Bharat

    2008-04-28

    Friction and wear are part and parcel of all walks of life, and for interfaces that are in close or near contact, tribology and mechanics are supremely important. They can critically influence the efficient functioning of devices and components. Nanoscale friction force follows a complex nonlinear dependence on multiple, often interdependent, interfacial and material properties. Various studies indicate that nanoscale devices may behave in ways that cannot be predicted from their larger counterparts. Nanoscale friction and wear mapping can help identify some 'sweet spots' that would give ultralow friction and near-zero wear. Mapping nanoscale friction and wear as a function of operating conditions and interface properties is a valuable tool and has the potential to impact the very way in which we design and select materials for nanotechnology applications.

  14. Tissue factor activated thromboelastography correlates to clinical signs of bleeding in dogs

    DEFF Research Database (Denmark)

    Wiinberg, Bo; Jensen, Asger Lundorff; Rozanski, Elizabeth

    2009-01-01

    The ability of a laboratory assay to correlate to clinical phenotype is crucial for the accurate diagnosis and monitoring of haemostasis and is therefore challenging with currently used routine haemostasis assays. Thromboelastography (TEG) is increasingly used to evaluate haemostasis in humans...... and may well be of value in the workup of dogs suspected of having a haemostatic disorder. This study was undertaken to evaluate prospectively how tissue factor (TF) activated TEG correlated to clinical signs of bleeding in dogs, compared to a routine coagulation profile. A prospective case-control study...... was performed over a 2 year period from 2004-2006. Eligible dogs were those where the primary clinician requested a coagulation profile to evaluate haemostasis. The dogs were simultaneously evaluated with a TF-activated TEG assay. Twenty-seven dogs, characterised as hypo-coagulable based on the TEG parameter G...

  15. Characterization of skin friction coefficient, and relationship to stratum corneum hydration in a normal Chinese population.

    Science.gov (United States)

    Zhu, Y H; Song, S P; Luo, W; Elias, P M; Man, M Q

    2011-01-01

    Studies have demonstrated that some cutaneous biophysical properties vary with age, gender and body sites. However, the characteristics of the skin friction coefficient in different genders and age groups have not yet been well established. In the present study, we assess the skin friction coefficient in a larger Chinese population. A total of 633 subjects (300 males and 333 females) aged 0.15-79 years were enrolled. A Frictiometer FR 770 and Corneometer CM 825 (C&K MPA 5) were used to measure the skin friction coefficient and stratum corneum hydration, respectively, on the dorsal surface of the hand, the forehead and the canthus. In the females, the maximum skin friction coefficients on both the canthus and the dorsal hand skin were observed around the age of 40 years. In the males, the skin friction coefficient on the dorsal hand skin gradually increased from 0 to 40 years of age, and changed little afterward. Skin friction coefficients on some body sites were higher in females than in age-matched males in some age groups. On the canthus and the dorsal hand skin of females, a positive correlation was found between skin friction coefficient and stratum corneum hydration (p friction coefficient was positively correlated with stratum corneum hydration on the forehead and the dorsal hand skin (p friction coefficient varies with age, gender and body site, and positively correlates with stratum corneum hydration on some body sites. Copyright © 2010 S. Karger AG, Basel.

  16. Correlation of hs-CRP with environmental risk factors of nephropathy in type 2 diabetes

    Directory of Open Access Journals (Sweden)

    Jay Prakash Sah

    2015-06-01

    Full Text Available The objective of the present study was to investigate the association of hs-CRP levels with environmental risk factors of diabetic nephropathy like smoking, drinking alcohol, diet, age of diabetic patient, duration of diabetes, medication of diabetes, and blood pressure medication. A hospital-based quantitative study was conducted at the Department of Clinical Biochemistry of Manipal Teaching Hospital (MTH Pokhara, Nepal, with 89 patients suffering from type 2 diabetes. Blood samples (n=89 from the patients were collected and the serums were separated. On the other hand, data on environmental risk factors of nephropathy were collected by using standard questionnaire. In this study, serum hs-CRP level was not found to be correlated with smoking (p=0.111, alcohol consumption (p=0.722, diet (p=0.496, duration of diabetes (p=0.519, age of diabetic patient (p=0.369, medication of diabetes (p=0.734, and blood pressure medication (p=0.625. Hence, our study concludes that serum hs-CRP value in type 2 diabetic patients is insignificantly correlated with the risk factors especially smoking, drinking alcohol, diet, duration of diabetes, age of diabetic patient, medication of diabetes, and medication of blood pressure.

  17. Correlates of early pregnancy serum brain-derived neurotrophic factor in a Peruvian population.

    Science.gov (United States)

    Yang, Na; Levey, Elizabeth; Gelaye, Bizu; Zhong, Qiu-Yue; Rondon, Marta B; Sanchez, Sixto E; Williams, Michelle A

    2017-12-01

    Knowledge about factors that influence serum brain-derived neurotrophic factor (BDNF) concentrations during early pregnancy is lacking. The aim of the study is to examine the correlates of early pregnancy serum BDNF concentrations. A total of 982 women attending prenatal care clinics in Lima, Peru, were recruited in early pregnancy. Pearson's correlation coefficient was calculated to evaluate the relation between BDNF concentrations and continuous covariates. Analysis of variance and generalized linear models were used to compare the unadjusted and adjusted BDNF concentrations according to categorical variables. Multivariable linear regression models were applied to determine the factors that influence early pregnancy serum BDNF concentrations. In bivariate analysis, early pregnancy serum BDNF concentrations were positively associated with maternal age (r = 0.16, P pregnancy body mass index (BMI) (r = 0.17, P pregnancy BMI (β = 1.58, P pregnancy serum BDNF concentrations. Participants with moderate antepartum depressive symptoms (Patient Health Questionnaire-9 (PHQ-9) score ≥ 10) had lower serum BDNF concentrations compared with participants with no/mild antepartum depressive symptoms (PHQ-9 score pregnancy BMI, gestational age, and the presence of moderate antepartum depressive symptoms were statistically significantly associated with early pregnancy serum BDNF concentrations in low-income Peruvian women. Biological changes of CRP during pregnancy may affect serum BDNF concentrations.

  18. Factor Structure of the BPRS in Deaf People with Schizophrenia: Correlates to Language and Thought

    Science.gov (United States)

    Horton, Heather K.; Silverstein, Steven M.

    2010-01-01

    Introduction There has been a relative lack of research on deaf people with schizophrenia, and no data exist regarding symptom structure in this population. Thus we determined the factor structure of the 24-item Brief Psychiatric Rating Scale (BPRS) in deaf (n=34) and hearing (n=31) people with schizophrenia and compared it to a standard 4-factor solution. Method An obliquely rotated factor analysis produced a solution for the BPRS that resembled others in the literature. Symptom clusters were additionally compared to cognitive and social-cognitive abilities. Results Activity and disorganized symptoms were the most consistent correlates of visual- and thought and language-related skills for deaf and hearing subjects respectively. Affective symptoms and facial affect processing were positively correlated among deaf but not hearing subjects. Conclusions The data suggest that current symptom models of schizophrenia are valid in both hearing and deaf patients. However, relations between symptoms, cognition, and outcome from the general (hearing) literature cannot be generalized to deaf patients. Findings are broadly consistent with pathophysiologic models of schizophrenia suggesting a fundamental cortical processing algorithm operating across several domains of neural activity including vision, and thought and language. Support is provided for recent advances in social-cognitive interventions for people with schizophrenia. PMID:21480014

  19. Phonological performance measured by speech severity indices compared with correlated factors

    Directory of Open Access Journals (Sweden)

    Haydée Fiszbein Wertzner

    Full Text Available CONTEXT AND OBJECTIVE: Some factors seem to influence speech impairment among phonologically disordered children. The aim was to compare severity indices with some correlated factors. DESIGN AND SETTING: Observational, analytical and cross-sectional study conducted within the Language-Speech-Hearing Sciences Course, Universidade de São Paulo. METHOD: Fifty phonologically disordered children with ages ranging from 4 to 11 years took part. The indices were calculated from phonology tests and were correlated with anamnesis and audiological data. Student’s t test and Spearman’s correlation were used to compare percentages of consonants correct (PCC and process density index (PDI for children with and without otitis, upper respiratory histories and audiological abnormalities, with regard to whether or not they were comprehended during assessment, their ages when they started to speak and their ages at the assessment. RESULTS: The higher the age at the assessment was, the higher the PCC (imitation: 0.468; naming: 0.431; Spearman’s correlation and the lower the PDI (imitation: 0.459; naming: 0.431; the later the child started to speak, the lower the PCC (imitation p = 0.064; naming p = 0.050 and the higher the PDI (imitation p = 0.067; naming p = 0.042. There were differences between groups with and without upper respiratory history (PCC: imitation p = 0.016, naming p = 0.005; PDI: imitation p = 0.014, naming p = 0.008. There was no difference between the groups regarding otitis, comprehension during the assessment and audiological data. CONCLUSIONS: Children with upper respiratory histories who began to speak later presented more severe speech impairment indices.

  20. The prevalence of substance use among adolescents and its correlation with social and demographic factors

    Directory of Open Access Journals (Sweden)

    Rakić Dušica B.

    2014-01-01

    Full Text Available Backround/Aim. Adolescence is the period of greatest risk of starting to use substances: cigarette smoking, alcohol and illicit drugs. In the first decade of this millennium substance use among adolescents has increased. The aim of this study was to explore the prevalence of substances use among adolescents and its correlation with social and demographic factors. Methods. The study was conducted among adolescents in Novi Sad during 2010-2011 and included 594 conveniently selected adolescents (275 male and 319 female, aged 15-19 years. A special questionnaire was used and statistical analysis performed in SPSS17. The correlation between parameters was evaluated by the Pearson correlation method and frequency differences were analysed using χ2 test and starting level was p < 0.05. Results. The prevalence of substance use was statistically higher in males. Cigarettes were smoked daily by 21.45% males and 15.67% females (p < 0.01, alcohol was consumed by 81.6% males and 69.11% females (p < 0.001 and illicit drugs were used by 13.65% males and 8.30% females (p < 0.05. There was a positive correlation between smoking cigarettes and alcohol consumption, but negative between smoking cigarettes and the use of illicit drugs (p < 0.01. The prevalence of substance use was statistically higher among adolescents with poor achievement in school (p < 0.01, who lived in a broken home (illicit drugs p < 0.01 and who had more pocket money (cigarette smoking p < 0.01, and alcohol consumption p < 0.5. Conclusion. Stable family, lower amount of pocket money weekly and good school performance are protective factors in prevention of substances use among adolescents.

  1. The correlations between insulin-like growth factor I, insulin and gestational diabetes mellitus

    International Nuclear Information System (INIS)

    Xu Yongle; Yang Weiwen; Pu Xiangke

    2006-01-01

    Objectives; To research the correlation between insulin-like growth factor I (IGF-I), insulin and gestational diabetes mellitus (GDM). Methods: Thirty cases of GDM are taken as the GDM group. Thirty cases of normal pregnant women were taken as the control group. The insulin in maternal serum of these two groups were measured at 31 ± 1 weeks gestational age by radioimmunity. The IGF-I in maternal serum at 31 ± 1 weeks gestational age and IGF-I in umbilical serum at term delivery were measured by ELISA. results: There was no significant difference in IGF-I level in maternal serum between the GDM group and the control group (P>0.05) and there was significant difference between these two groups maternal LnIRI, IGF-I in umbilical serum and weight of newborn baby (P<0.01). In the GDM group, the IGF-I in maternal serum positively correlated with the LnIRI (r=0.424, P<0.05) and IGF-I in umbilical serum positively correlated with the weight of new-born baby (r=0.434, P<0.05). Conclusion: GDM has serious insulin resistance. The IGF-I in maternal serum correlated with the IR in GDM. IGF-I in umbilical serum plays a role in the pathology and physiology process of fetal macrosomia. Abnormality of the axis of growth hormone-insulin-insulin-like growth factor caused by IGF-I might be through the way of insulin resistance, and GDM is resulted. (authors)

  2. Finger pad friction and its role in grip and touch.

    Science.gov (United States)

    Adams, Michael J; Johnson, Simon A; Lefèvre, Philippe; Lévesque, Vincent; Hayward, Vincent; André, Thibaut; Thonnard, Jean-Louis

    2013-03-06

    Many aspects of both grip function and tactile perception depend on complex frictional interactions occurring in the contact zone of the finger pad, which is the subject of the current review. While it is well established that friction plays a crucial role in grip function, its exact contribution for discriminatory touch involving the sliding of a finger pad is more elusive. For texture discrimination, it is clear that vibrotaction plays an important role in the discriminatory mechanisms. Among other factors, friction impacts the nature of the vibrations generated by the relative movement of the fingertip skin against a probed object. Friction also has a major influence on the perceived tactile pleasantness of a surface. The contact mechanics of a finger pad is governed by the fingerprint ridges and the sweat that is exuded from pores located on these ridges. Counterintuitively, the coefficient of friction can increase by an order of magnitude in a period of tens of seconds when in contact with an impermeably smooth surface, such as glass. In contrast, the value will decrease for a porous surface, such as paper. The increase in friction is attributed to an occlusion mechanism and can be described by first-order kinetics. Surprisingly, the sensitivity of the coefficient of friction to the normal load and sliding velocity is comparatively of second order, yet these dependencies provide the main basis of theoretical models which, to-date, largely ignore the time evolution of the frictional dynamics. One well-known effect on taction is the possibility of inducing stick-slip if the friction decreases with increasing sliding velocity. Moreover, the initial slip of a finger pad occurs by the propagation of an annulus of failure from the perimeter of the contact zone and this phenomenon could be important in tactile perception and grip function.

  3. Analysis of angiogenic factors and cyclooxygenase-2 expression in cartilaginous tumors: clinical and histological correlation

    Directory of Open Access Journals (Sweden)

    Francisco Fontes Cintra

    2011-01-01

    Full Text Available OBJECTIVES: To study the role of angiogenesis and cyclooxygenase-2 expression in cartilaginous tumors and correlate these factors with prognosis. INTRODUCTION: For chondrosarcoma, the histological grade is the current standard for predicting tumor outcome. However, a low-grade chondrosarcoma can follow an aggressive course-as monitored by sequential imaging techniques-even when it is histologically indistinguishable from an enchondroma. Therefore, additional tools are needed to help identify the biological potential of these tumors. The degree of angiogenesis that is induced by the tumor could assist in this task. Angiogenesis can be quantified by measuring the expression of vascular endothelial growth factor and CD34, and cyclooxygenase-2 can induce angiogenesis by stimulating the production of proangiogenic factors. METHODS: In total, 21 enchondromas and 58 conventional chondrosarcomas were studied by examining the clinical and histopathological findings in conjunction with the immunostaining markers of angiogenesis and cyclooxygenase- 2 expression. RESULTS: The significant variables that were associated with poor outcome were 1 higher-grade chondrosarcomas, 2 tumors that developed in flat bones, and 3 over-expression of CD34 (with a median count that was higher than 5.9 vessels in 5 high power fields. Moreover, CD34 expression (measured using the Chalkley method revealed significantly higher microvessel density in flat bone chondrosarcomas. DISCUSSION: Previous studies have shown a positive correlation between Chalkley microvessel density and histological grade; however, in our sample, we found that the former is predictive of the outcome. Chondrosarcomas in flat bones have been shown to correlate with a poor prognosis. We also found that CD34 microvessel density values were significantly higher in flat-bone chondrosarcomas. This could explain-at least in part-the more aggressive biological course that is taken by these tumors. CONCLUSIONS

  4. Eliminating friction with friction: 2D Janssen effect in a friction-driven system.

    Science.gov (United States)

    Karim, M Yasinul; Corwin, Eric I

    2014-05-09

    The Janssen effect is a unique property of confined granular materials experiencing gravitational compaction in which the pressure at the bottom saturates with an increasing filling height due to frictional interactions with side walls. In this Letter, we replace gravitational compaction with frictional compaction. We study friction-compacted 2D granular materials confined within fixed boundaries on a horizontal conveyor belt. We find that even with high-friction side walls the Janssen effect completely vanishes. Our results demonstrate that gravity-compacted granular systems are inherently different from friction-compacted systems in at least one important way: vibrations induced by sliding friction with the driving surface relax away tangential forces on the walls. Remarkably, we find that the Janssen effect can be recovered by replacing the straight side walls with a sawtooth pattern. The mechanical force introduced by varying the sawtooth angle θ can be viewed as equivalent to a tunable friction force. By construction, this mechanical friction force cannot be relaxed away by vibrations in the system.

  5. Climate Change Risk Perception in Taiwan: Correlation with Individual and Societal Factors.

    Science.gov (United States)

    Sun, Yingying; Han, Ziqiang

    2018-01-08

    This study differentiates the risk perception and influencing factors of climate change along the dimensions of global severity and personal threat. Using the 2013 Taiwan Social Change Survey (TSGS) data (N = 2001) as a representative sample of adults from Taiwan, we investigated the influencing factors of the risk perceptions of climate change in these two dimensions (global severity and personal threat). Logistic regression models were used to examine the correlations of individual factors (gender, age, education, climate-related disaster experience and risk awareness, marital status, employment status, household income, and perceived social status) and societal factors (religion, organizational embeddedness, and political affiliations) with the above two dimensions. The results demonstrate that climate-related disaster experience has no significant impact on either the perception of global severity or the perception of personal impact. However, climate-related risk awareness (regarding typhoons, in particular) is positively associated with both dimensions of the perceived risks of climate change. With higher education, individuals are more concerned about global severity than personal threat. Regarding societal factors, the supporters of political parties have higher risk perceptions of climate change than people who have no party affiliation. Religious believers have higher risk perceptions of personal threat than non-religious people. This paper ends with a discussion about the effectiveness of efforts to enhance risk perception of climate change with regard to global severity and personal threat.

  6. Factors correlating with significant differences between X-ray structures of myoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Rashin, Alexander A., E-mail: alexander-rashin@hotmail.com [BioChemComp Inc., 543 Sagamore Avenue, Teaneck, NJ 07666 (United States); Iowa State University, 112 Office and Lab Bldg, Ames, IA 50011-3020 (United States); Domagalski, Marcin J. [University of Virginia, 1340 Jefferson Park Avenue, Jordan Hall, Room 4223, Charlottesville, VA 22908 (United States); Zimmermann, Michael T. [Iowa State University, 112 Office and Lab Bldg, Ames, IA 50011-3020 (United States); Minor, Wladek [University of Virginia, 1340 Jefferson Park Avenue, Jordan Hall, Room 4223, Charlottesville, VA 22908 (United States); Chruszcz, Maksymilian [University of Virginia, 1340 Jefferson Park Avenue, Jordan Hall, Room 4223, Charlottesville, VA 22908 (United States); University of South Carolina, 631 Sumter Street, Columbia, SC 29208 (United States); Jernigan, Robert L. [Iowa State University, 112 Office and Lab Bldg, Ames, IA 50011-3020 (United States); BioChemComp Inc., 543 Sagamore Avenue, Teaneck, NJ 07666 (United States)

    2014-02-01

    Conformational differences between myoglobin structures are studied. Most structural differences in whale myoglobin beyond the uncertainty threshold can be correlated with a few specific structural factors. There are always exceptions and a search for additional factors is needed. The results might have serious implications for biological insights from conformational differences. Validation of general ideas about the origins of conformational differences in proteins is critical in order to arrive at meaningful functional insights. Here, principal component analysis (PCA) and distance difference matrices are used to validate some such ideas about the conformational differences between 291 myoglobin structures from sperm whale, horse and pig. Almost all of the horse and pig structures form compact PCA clusters with only minor coordinate differences and outliers that are easily explained. The 222 whale structures form a few dense clusters with multiple outliers. A few whale outliers with a prominent distortion of the GH loop are very similar to the cluster of horse structures, which all have a similar GH-loop distortion apparently owing to intermolecular crystal lattice hydrogen bonds to the GH loop from residues near the distal histidine His64. The variations of the GH-loop coordinates in the whale structures are likely to be owing to the observed alternative intermolecular crystal lattice bond, with the change to the GH loop distorting bonds correlated with the binding of specific ‘unusual’ ligands. Such an alternative intermolecular bond is not observed in horse myoglobins, obliterating any correlation with the ligands. Intermolecular bonds do not usually cause significant coordinate differences and cannot be validated as their universal cause. Most of the native-like whale myoglobin structure outliers can be correlated with a few specific factors. However, these factors do not always lead to coordinate differences beyond the previously determined uncertainty

  7. THE CORRELATION AMONG ATTITUDE, MOTIVATION AND SPEAKING ACHIEVEMENT OF COLLEGE STUDENTS ACROSS PERSONALITY FACTORS

    Directory of Open Access Journals (Sweden)

    Siti Lailatul Khoiriyah

    2016-05-01

    Full Text Available Considering the important of understanding about the attitude, motivation and the personality of the students in the English learning process, this research is aimed at finding the relationship between attitude and motivation which are acknowledged as influential factors in speaking achievement across their personality factors. Sixty Non-EFL students of Maulana Malik Ibrahim State Islamic University of Malang who take English as their compulsory subject were participated as the research sample. They were the fourth semester undergraduate taking TOEFL and Speaking Course. Attitude and Motivation Test Battery (AMTB, The Myers-Briggs Type Indicator (MBTI, speaking test and TOEFL-like test were administered. The results of this research revealed that there was significant correlation among attitude, motivation and speaking achievement of extrovert and Introvert students.

  8. Frictional performance of ball screw

    International Nuclear Information System (INIS)

    Nakashima, Katuhiro; Takafuji, Kazuki

    1985-01-01

    As feed screws, ball screws have become to be adopted in place of trapezoidal threads. The structure of ball screws is complex, but those are the indispensable component of NC machine tools and machining centers, and are frequently used for industrial robots. As the problems in the operation of ball screws, there are damage, life and the performance related to friction. As to the damage and life, though there is the problem of the load distribution on balls, the results of the research on rolling bearings are applied. The friction of ball screws consists of the friction of balls and a spiral groove, the friction of a ball and a ball, the friction in a ball-circulating mechanism and the viscous friction of lubricating oil. It was decided to synthetically examine the frictional performance of ball screws, such as driving torque, the variation of driving torque, efficiency, the formation of oil film and so on, under the working condition of wide range, using the screws with different accuracy and the nuts of various circuit number. The experimental setup and the processing of the experimental data, the driving performance of ball screws and so on are reported. (Kako, I.)

  9. Friction and wear of some ferrous-base metallic glasses

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.

    1984-01-01

    Sliding friction experiments, X-ray photoelectron spectroscopy (XPS) analysis, and electron microscopy and diffraction studies were conducted with ferrous base metallic glasses (amorphous alloys) in contact with aluminium oxide at temperatures to 750 C in a vacuum. Sliding friction experiments were also conducted in argon and air atmospheres. The results of the investigation indicate that the coefficient of friction increases with increasing temperature to 350 C in vacuum. The increase in friction is due to an increase in adhesion resulting from surface segregation of boric oxide and/or silicon oxide to the surface of the foil. Above 500 C the coefficient of friction decreased rapidly. The decrease correlates with the segregation of boron nitride to the surface. Contaminants can come from the bulk of the material to the surface upon heating and impart boric oxide and/or silicon oxide at 350 C and boron nitride above 500 C. The segregation of contaminants is responsible for the friction behavior. The amorphous alloys have superior wear resistance to crystalline 304 stainless steel. The relative concentrations of the various constituents at the surfaces of the amorphous alloys are very different from the nominal bulk compositions.

  10. The correlation between perceived social support, cortisol and brain derived neurotrophic factor levels in healthy women.

    Science.gov (United States)

    Ma, Doy Yung; Chang, Wei Hung; Chi, Mei Hung; Tsai, Hsin Chun; Yang, Yen Kuang; Chen, Po See

    2016-05-30

    In this study, the role of brain derived neurotrophic factor (BDNF) in stress resilience was investigated. With a focus on healthy subjects, we explored whether plasma BDNF levels are correlated with the dexamethasone suppression test (DST) and subjectively perceived social support status. Moreover, we examined the possible interacting effect of DST status and perceived social support on BDNF levels. Seventy-two healthy volunteers, 44 females and 28 males, were recruited from the community and completed the perceived routine support subscale of Measurement of Support Function (PRS_MSF) questionnaire. Plasma BDNF levels and DST suppression rate with the low dose DST were measured. There was a significant positive correlation between BDNF and DST suppression rate in the female subjects. This was also true for the plasma BDNF levels and PRS_MSF in the female subjects. The positive correlation between BDNF and PRS_MSF was significant only in female subjects with low DST suppression rates. Plasma BDNF levels were associated with stress resilience in a sex-specific manner. Subjects' belief in social support might buffer the biological stress reactions. Differences in social perception and the biological stress response between men and women merits further investigation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  11. Correlation between matrix metalloproteinase-9 and vascular endothelial growth factor expression in lung adenocarcinoma.

    Science.gov (United States)

    Wen, Y L; Li, L

    2015-12-29

    The aim of this study was to investigate the correlation between the expression of matrix metalloproteinase-9 (MMP-9) and vascular endothelial growth factor (VEGF) and clinicopathological features of lung adenocarcinoma. The expression of MMP-9 and VEGF was evaluated by immunohistochemistry of 30 samples from lung adenocarcinoma patients and 12 paratumoral (normal) tissue samples. In addition, the change in VEGF or MMP-9 expression after MMP-9 or VEGF blockade, respectively, was measured using western blot in lung adenocarcinoma A549 cells. High expression of MMP-9 was found in 63.3% of adenocarcinoma tissues versus 16.7% in normal tissues (P correlation was identified between MMP-9 and VEGF expression (correlation coefficient = 0.7094, P < 0.001), and their mutual overexpression was associated with clinical staging and lymph node status (P < 0.05). In addition, an decrease in VEGF protein expression was observed after MMP-9 blockade by an MMP-9-specific monoclonal antibody. Similarly, a decrease in MMP-9 protein expression was found after VEGF blockade by a VEGF-specific monoclonal antibody. In conclusion, VEGF and MMP-9 are overexpressed in lung adenocarcinoma tissues, and they have a synergistic effect on the invasion and metastasis of adenocarcinoma.

  12. The prevalence, risk factors and clinical correlates of obesity in Chinese patients with schizophrenia.

    Science.gov (United States)

    Li, Qiongzhen; Du, Xiangdong; Zhang, Yingyang; Yin, Guangzhong; Zhang, Guangya; Walss-Bass, Consuelo; Quevedo, João; Soares, Jair C; Xia, Haishen; Li, Xiaosi; Zheng, Yingjun; Ning, Yuping; Zhang, Xiang Yang

    2017-05-01

    Obesity is a common comorbidity in schizophrenia. Few studies have addressed obesity in Chinese schizophrenia patients. The aims of this current study were to evaluate the prevalence, risk factors and clinical correlates of obesity in Chinese patients with schizophrenia. A total of 206 patients were recruited from a hospital in Beijing. Their clinical and anthropometric data together with plasma glucose and lipid parameters were collected. Positive and Negative Syndrome Scale (PANSS) was rated for all patients. Overall, 43 (20.9%) patients were obese and 67 (32.5%) were overweight. The obese patients had significantly higher glucose levels, triglyceride levels than non-obese patients. Females and patients with type 2 diabetes mellitus had increased risk for obesity. Correlation analysis showed that BMI was associated with sex, education levels, negative symptoms, total PANSS score, triglyceride levels and type 2 diabetes mellitus. Further stepwise regression analysis showed that sex, type 2 diabetes, education level, triglyceride and amount of smoking/day were significant predictors for obesity. Our study showed that the prevalence of obesity in Chinese patients with schizophrenia is higher than that in the general population. Some demographic and clinical variables are risk factors for obesity in schizophrenia. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  13. The correlation of prenatal zinc concentration and deficiency with anthropometric factors.

    Directory of Open Access Journals (Sweden)

    Parichehr Hanachi

    2014-03-01

    Full Text Available To determine the status of serum zinc in pregnant women in different gestational ages and correlation with socio-demographic and anthropometric factors in Iranian women referring to prenatal care public health clinics.We analyzed the zinc concentrations in plasma samples obtained at different gestational ages from 961 women and recorded BMI at the first trimester in pregnant women who were screened for a trial designed to evaluate the zinc concentration. Subjects were from different socio economical backgrounds and attended public health clinics for their prenatal care. All analyses were performed by SPSS (version 16. P values < 0.05 were considered significant.The results showed that after plasma zinc concentrations were adjusted with Parity, weight (early pregnancy, BMI (at early pregnancy, age and educational statues. Plasma zinc deficiency declined as gestational age progressed, however it was not significant. There was no significant correlation between zinc concentration, anthropometric, method of contraception and socio factors. However, there were significant relation between parity (p = 0.007 and weight at early pregnancy (p= 0.039 with serum zinc levels.We conclude that plasma zinc concentrations decreased during the late first trimester to the early third trimester and with parity. These findings may indicate that the deficient levels of zinc in the latter third of pregnancy suggest a tendency for insufficient maternal nutrition. However larger studies are required to support this finding.

  14. Correlated biochemical modifications of plasma lipoproteins in coronary heart disease: an accelerating pathologic factor.

    Science.gov (United States)

    Sima, A; Hobai, I; Stancu, C; Cinteză, M; Gherasim, L

    1996-01-01

    We investigated the presence of biochemically modified plasma lipoproteins as pathologic factor for coronary heart disease in 15 patients with angina pectoris (CHD-P) vs 20 normal subjects (N). Decreased HDL were the most significant pathological feature present in P over 66 years old, while, P under 66 had, in addition to low HDL-Cholesterol (HDL-C), high levels of plasma cholesterol (C), LDL-Cholesterol (LDL-C), and lipid peroxides (TBARS), together with the presence of desialylated LDL and VLDL. We demonstrated by statistic analysis that these risk factors are correlated: high plasma C with a more pronounced imbalance between LDL and HDL, which, in turn, is associated with high TBARS levels, and also with circulating desialylated VLDL; high plasma TBARS values with desialylated LDL. We detected an increased level of autoantibodies towards autologous LDL and VLDL, in P vs N. The level of autoantibodies anti-LDL correlated with LDL-C level and with LDL desialylation, thus modified circulating LDL being most probably atherogenic. Circulating anti-LDL autoantibodies together with the low level of HDL might contribute to acceleration and aggravation of the atherosclerotic process.

  15. Friction and wear performance of ion-beam deposited diamondlike carbon films on steel substrates

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.; Nichols, F.A.; Pan, X.Z. [Argonne National Lab., IL (United States). Materials and Components Technology Div.; Wei, R.; Wilbur, P. [Colorado State Univ., Fort Collins, CO (United States). Dept. of Mechanical Engineering

    1993-01-01

    In this study, we investigated the friction and wear performance of ion-beam-deposited diamondlike-carbon (DLC) films (1.5 {mu}m thick) on AISI 440C steel substrates. Furthermore, we ran a series of long-duration wear tests under 5, 10, and 20 N load to assess the load-bearing capacity and durability limits of these films under each load. Tests were performed on a ball-on-disk machine in open air at room temperature {approx} 22{plus_minus}1{degrees}C, and humidity, {approx} 30{plus_minus}5%. For the test conditions explored, we found that (1) the steady-state friction coefficients of pairs without a DLC film were in the range of 0.7 to 0.9 and the average wear rates of 440C balls (9.55 mm diameter) sliding against uncoated 440C disks were on the order of 10{sup {minus}5} mm{sup 3}/N.m, depending on contact load; (2) DLC films reduced the steady-state friction coefficients of test pairs by factors of 6 to 8, and the wear rates of pins by factors of 500 to 2000; (3) The wear of disks coated with a DLC film was virtually unmeasurable while the wear of uncoated disks was quite substantial, (4) these DLC films were able to endure the range of loads, 5 to 20 N, without any delamination and to last over a million cycles before wearing out. During long-duration wear tests, the friction coefficients were initially on the order of 0.15, but decreased to some low values of 0.05 to 0.07 after sliding for 15 to 25 km, depending on the load, and remained low until wearing out. This low-friction regime was correlated with the formation of a carbon-rich transfer film on the wear scar of 440C balls. Micro-laser-Raman spectroscopy and scanning-electron microscopy were used to examine the structure and chemistry of worn surfaces and to elucidate the wear- and friction-reducing mechanisms of the DLC film.

  16. Friction and wear performance of ion-beam deposited diamondlike carbon films on steel substrates

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.; Nichols, F.A.; Pan, X.Z. (Argonne National Lab., IL (United States). Materials and Components Technology Div.); Wei, R.; Wilbur, P. (Colorado State Univ., Fort Collins, CO (United States). Dept. of Mechanical Engineering)

    1993-01-01

    In this study, we investigated the friction and wear performance of ion-beam-deposited diamondlike-carbon (DLC) films (1.5 [mu]m thick) on AISI 440C steel substrates. Furthermore, we ran a series of long-duration wear tests under 5, 10, and 20 N load to assess the load-bearing capacity and durability limits of these films under each load. Tests were performed on a ball-on-disk machine in open air at room temperature [approx] 22[plus minus]1[degrees]C, and humidity, [approx] 30[plus minus]5%. For the test conditions explored, we found that (1) the steady-state friction coefficients of pairs without a DLC film were in the range of 0.7 to 0.9 and the average wear rates of 440C balls (9.55 mm diameter) sliding against uncoated 440C disks were on the order of 10[sup [minus]5] mm[sup 3]/N.m, depending on contact load; (2) DLC films reduced the steady-state friction coefficients of test pairs by factors of 6 to 8, and the wear rates of pins by factors of 500 to 2000; (3) The wear of disks coated with a DLC film was virtually unmeasurable while the wear of uncoated disks was quite substantial, (4) these DLC films were able to endure the range of loads, 5 to 20 N, without any delamination and to last over a million cycles before wearing out. During long-duration wear tests, the friction coefficients were initially on the order of 0.15, but decreased to some low values of 0.05 to 0.07 after sliding for 15 to 25 km, depending on the load, and remained low until wearing out. This low-friction regime was correlated with the formation of a carbon-rich transfer film on the wear scar of 440C balls. Micro-laser-Raman spectroscopy and scanning-electron microscopy were used to examine the structure and chemistry of worn surfaces and to elucidate the wear- and friction-reducing mechanisms of the DLC film.

  17. Altered expression of platelet factor 4 and basic fibroblast growth factor correlates with the inhibition of tumor growth in mice.

    Science.gov (United States)

    Mabeta, Peace; Pepper, Michael S

    2015-02-01

    Herein, we describe the effects of Taxol on endothelioma cell growth and migration in vitro and on vascular tumor growth in vivo. The effects of Taxol on endothelioma cell growth were determined using the crystal violet assay, while cell migration was measured using the xCELLIgence Real-Time Cell Analysis system. To study the effects of Taxol on tumor growth, mice were inoculated with endothelioma cells to induce vascular tumor development and were treated with the drug. At termination, tissue samples from Taxol-treated and control mice were stained with hematoxylin and eosin for histological examination, while blood samples were collected for hematological analysis, as well as for the analysis of the expression of angiogenic markers. In vitro, Taxol inhibited cell growth and migration. The drug also inhibited vascular tumor growth in mice, and this correlated with a recovery of mice from thrombocytopenia. Array analysis of blood samples from mice revealed that there was an increase in the expression of platelet factor 4 and a suppression of the proangiogenic molecule basic fibroblast growth factor in Taxol-treated animals. Our findings suggest that Taxol may have potential in the treatment of vascular tumors. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  18. Factors that determine self-reported immunosuppressant adherence in kidney transplant recipients: a correlational study.

    Science.gov (United States)

    Weng, Li-Chueh; Yang, Ya-Chen; Huang, Hsiu-Li; Chiang, Yang-Jen; Tsai, Yu-Hsia

    2017-01-01

    To determine the factors related to immunosuppressant therapy adherence in kidney transplant recipients in Taiwan. Adherence to immunosuppressant treatment is critical after kidney transplantation. Thus, the factors associated with self-reported medication adherence in kidney transplant recipients warrant investigation. The study used a cross-sectional and correlation design. A convenience sample of 145 kidney transplant recipients was included. Structured questionnaires were used to collect data during 2012-2013. Multivariate linear regression was used to examine the factors related to immunosuppressant therapy adherence. Over half of the participants were female (54·5%), mean age was 45·5 years, and mean year after transplant was 7·4. The mean score for medication adherence was 29·73 (possible score range 7-35). The results of the multivariate linear regression analysis showed that gender (male), low income with a high school or college education, years after transplantation and concerns about medication taking were negatively associated with adherence. Medication self-efficacy was positively associated with adherence. Therapy-related factors, partnerships with healthcare professionals and having private healthcare insurance did not significantly relate to immunosuppressant therapy adherence. Kidney transplant recipients demonstrated a high level of adherence. Strategies to enhance patients' self-efficacy and alleviate concerns about medication may promote medication adherence. Male patients, those with a lower income and those with a higher education level, should be a focus of efforts to maintain adherence to the medication regimen. © 2016 John Wiley & Sons Ltd.

  19. Clinicopathological correlation of keratinocyte growth factor and matrix metalloproteinase-9 expression in human gastric cancer.

    Science.gov (United States)

    Zhang, Qing; Wang, Ping; Shao, Ming; Chen, Shi-Wen; Xu, Zhi-Feng; Xu, Feng; Yang, Zhong-Yin; Liu, Bing-Ya; Gu, Qin-Long; Zhang, Wen-Jian; Li, Yong

    2015-01-01

    Keratinocyte growth factor (KGF) is reported to be implicated in the growth of some cancer cells. Matrix metalloproteinase 9 (MMP-9) is thought to enhance the tumor invasion and metastasis ability. This study was aimed at analyzing the relationship between KGF and MMP-9 expression and patients' clinicopathological characteristics to clarify the clinical significance of the expression of KGF and MMP-9 in gastric cancer. Tissue samples from 161 patients with primary gastric cancer were investigated using immunohistochemistry. The relationship between KGF and/or MMP-9 expression and clinicopathological characteristics was analyzed. KGF expression and MMP-9 expression in gastric cancer tissue were observed in 62 cases (38.5%) and 97 cases (60.2%), respectively. MMP-9 was significantly associated with depth of invasion, lymph node metastasis and TNM stage. The prognosis of MMP-9-positive patients was significantly poorer than that of MMP-9-negative patients (p = 0.009). KGF expression was positively correlated with MMP-9 expression in gastric cancer, and the prognosis of patients with both KGF- and MMP-9-positive tumors was significantly worse than that of patients with negative tumors for either factor (p = 0.045). Expression of MMP-9 was revealed to be an independent prognostic factor (p = 0.026). Coexpression of KGF and MMP-9 in gastric cancer could be a useful prognostic factor, and MMP-9 might also serve as a novel target for both prognostic prediction and therapeutics.

  20. Correlation between educational status and cardiovascular risk factors in an overweight and obese Turkish female population.

    Science.gov (United States)

    Tanyolaç, Sinan; Sertkaya Cikim, Ayşe; Doğan Azezli, Adil; Orhan, Yusuf

    2008-10-01

    The prevalence of obesity is rapidly increasing in Turkey as well as all over the world. Educational inequalities play an important role in the development of obesity. In this study, our aim is to evaluate how educational status affects obesity and cardiovascular risk factors in the overweight and obese Turkish female population. In this study, 3080 overweight (n=633) and obese (n=2447) Turkish women who applied to Istanbul Faculty of Medicine Obesity Outpatient Clinic were evaluated retrospectively. Educational status was classified according to the subjects' latest term of education. Subjects were evaluated in terms of anthropometric and biochemical parameters. The association of educational level with cardiovascular risk factors and metabolic syndrome were analyzed using logistic regression analysis. Educational levels after adjusted continuous variables (age and body mass index) showed significant correlation with waist circumference, total and high-density lipoprotein cholesterol, triglycerides, low-density lipoprotein cholesterol and glucose. Low educated class (LEC) had a 1.93 (95% CI--1.56-2.39, p=0.001) fold increased risk than high educated subjects for cardiovascular risk factors. Metabolic syndrome prevalence was more prevalent and significant risk increase was observed in LEC (OR=2.02, 95% CI--.53-2.67, p=0.001). Low educational status is a contributing factor for development of obesity and increased risk for obesity related disorders in the Turkish overweight and obese female population. Population based information and educational policies might prevent obesity related disorders and decrease cardiovascular mortality.

  1. Influence of self-affine roughness on the friction coefficient of rubber at high sliding velocity

    NARCIS (Netherlands)

    Palasantzas, G

    2004-01-01

    In this work we investigate the influence of self-affine roughness on the friction coefficient of a rubber body onto a solid surface at high speeds. The roughness is characterized by the rms amplitude w, the correlation length xi, and the roughness exponent H. It is shown that the friction

  2. Labor Supply and Optimization Frictions

    DEFF Research Database (Denmark)

    Søgaard, Jakob Egholt

    In this paper I investigate the nature of optimization frictions by studying the labor market of Danish students. This particular labor market is an interesting case study as it features a range of special institutional settings that affect students’ incentive to earn income and comparing outcomes...... across these setting effectively allow you to distinguish between different types of frictions. I find that the considered labor market is significantly affected by optimizations frictions, which masks the bunching at kink points normally associated with a positive labor supply elasticity under standard...

  3. Frictional properties of confined polymers

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N; Persson, Bo N J

    2008-01-01

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively...... independent of molecular length. For polymer sliding on polymer the friction is significantly larger, and dependent on the molecular chain length. In both cases, the shear stresses are proportional to the squeezing pressure and finite at zero load, indicating an adhesional contribution to the friction force...

  4. REDUCED ENGINE FRICTION AND WEAR

    Energy Technology Data Exchange (ETDEWEB)

    Ron Matthews

    2005-05-01

    This Final Technical Report discusses the progress was made on the experimental and numerical tasks over the duration of this project regarding a new technique for decreasing engine friction and wear via liner rotation. The experimental subtasks involved quantifying the reduction in engine friction for a prototype rotating liner engine relative to a comparable baseline engine. Both engine were single cylinder conversions of nominally identical production four-cylinder engines. Hot motoring tests were conducted initially and revealed that liner rotation decreased engine friction by 20% under motoring conditions. A well-established model was used to estimate that liner rotation should decrease the friction of a four-cylinder engine by 40% under hot motoring conditions. Hot motoring tear-down tests revealed that the crankshaft and valve train frictional losses were essentially the same for the two engines, as expected. However, the rotating liner engine had much lower (>70%) piston assembly friction compared to the conventional engine. Finally, we used the Instantaneous IMEP method to compare the crank-angle resolved piston assembly friction for the two engines. Under hot motoring conditions, these measurements revealed a significant reduction in piston assembly friction, especially in the vicinity of compression TDC when the lubrication regime transitions from hydrodynamic through mixed and into boundary friction. We have some remaining problems with these measurements that we expect to solve during the next few weeks. We will then perform these measurements under firing conditions. We also proposed to improve the state-of-the-art of numerical modeling of piston assembly friction for conventional engines and then to extend this model to rotating liner engines. Our research team first modeled a single ring in the Purdue ring-liner test rig. Our model showed good agreement with the test rig data for a range of speeds and loads. We then modeled a complete piston

  5. Medication adherence among Nigerians with schizophrenia: correlation between clinico-demographic factors and quality of life

    Directory of Open Access Journals (Sweden)

    Oluseun P. Ogunnubi

    2017-03-01

    Full Text Available Medication adherence contributes significantly to symptom remission, recovery and wellbeing in mental illnesses. We evaluated how medication adherence correlates with clinico-demographic factors and quality of life (QoL in a sample of Nigerians with schizophrenia. This descriptive crosssectional study involved 160 randomly selected participants with confirmed diagnosis of schizophrenia based on MINI International Neuropsychiatric Interview. Data on socio-demographic and clinical characteristics of participants were collected with a questionnaire. Medication adherence was assessed with Morisky Medication Adherence Questionnaire, and participants completed the World Health Organization Quality of Life Scale-BREF. The mean age of participants was 38.54 (±11.30 years, and all the participants were on antipsychotics, but only 45% were adherent to their medication. Out of all the participants, 45 (28.2% considered their overall QoL to be good, 97 (60.6% considered theirs to be fair, while 18 (11.2% reported poor QoL. Medication non-adherence correlated negatively with good QoL across multiple dimensions including overall QoL (r=- 0.175, health satisfaction (r=-0.161, physical (r=-0.186 and psychological domain (r=-0.175. Again, participant’s age (r=- 0.190 and age of onset of illness (r=-0.172 correlated negatively with medication nonadherence, and a trend towards relapse delay with medication adherence was also observed (r=-0.155. The effect size of these correlations were however small. Our findings suggest a link between medication adherence and QoL in schizophrenia, such that strategy that addresses medication nonadherence and its determinants may have potential benefits on wellbeing. Further hypotheses-driven studies are desirable.

  6. Psychological factors are important correlates of dietary pattern in overweight adults.

    Science.gov (United States)

    Grossniklaus, Daurice A; Dunbar, Sandra B; Tohill, Beth C; Gary, Rebecca; Higgins, Melinda K; Frediani, Jennifer

    2010-01-01

    Abdominal obesity, the central distribution of adipose tissue, is a well-established cardiometabolic disease risk factor. The prevalence has steadily increased since 1988, and now more than 50% of adults have abdominal obesity. Psychological distress coupled with increased dietary energy density (ED) may contribute to abdominal obesity. Guided by the stress and coping model, this study examined the relationship between psychological factors (perceived stress and depressive symptoms) and dietary ED in overweight, working adults. The first hypothesis tested if psychological factors explained a significant amount of food and beverage ED variance above that accounted for by demographic factors. The second hypothesis tested if psychological factors explained a significant amount of food and nonalcoholic beverage ED variance above that accounted for by demographic factors. Post hoc analyses compared macronutrient composition and food group pattern between overweight, working adults with and without depressive symptoms. This descriptive, cross-sectional, correlation study was composed of 87 overweight, working adults (mean age, 41.3 [SD, 10.2] years; mean body mass index, 32.1 [SD, 6.1] kg/m²; 73.6% women; 50.6% African American). Participants completed the Beck Depression Inventory II and Perceived Stress Scale and weighed-3-day-food record analyzed for caloric intake (kilocalories) and weight (in grams) of consumed foods and beverages that were used to calculate ED (in kilocalories/gram). Height and weight were measured to calculate body mass index. Descriptive statistics, Mann-Whitney U test, and sequential regression modeling were used for data analysis. Depressive symptoms were reported by 21.9% of participants and explained variance in food and beverage ED above that accounted for by African American race and reporting adequate caloric intake. Depressive symptoms explained variance in food and nonalcoholic beverage ED above that accounted for male sex, African

  7. Correlations Between Quality of Life and Psychological Factors in Patients With Chronic Neck Pain

    Directory of Open Access Journals (Sweden)

    Rong-Fong Lin

    2010-01-01

    Full Text Available The purpose of this study was to investigate health-related quality of life (HRQOL and associated factors in patients with chronic neck pain (CNP. The HRQOL of patients with CNP was assessed by the Short Form-36 questionnaire in this cross-sectional study. To evaluate the psychological factors related to HRQOL, the Eysenck Personality Questionnaire, Chinese Health Questionnaire, and Beck Anxiety Inventory were used. The scores for the eight subscales of Short Form-36 were all lower than the Taiwanese age-matched normative values (p < 0.001. The two most strongly affected subscales were the role–physical subscale and the bodily pain sub-scale; both scores were below half the score of the age-/sex-matched normative values. The physical components summary score, a summary measure, was moderately correlated with age (ρ = −0.43, education level (ρ = 0.37 and Beck Anxiety Inventory score (ρ = −0.36. The mental components summary score was moderately to highly correlated with the Chinese Health Questionnaire score (ρ = −0.72, the neuroticism domain of Eysenck Personality Questionnaire (ρ = −0.52 and Beck Anxiety Inventory score (ρ = −0.41. The HRQOL of patients with CNP was worse than that of normal subjects across all domains. Furthermore, patients with a neurotic personality, minor psychiatric morbidity and higher anxiety status showed poor mental health, as measured by the Short Form-36. We found that patients with CNP had multiple physical and mental health problems in terms of. The mental health of patients with CNP was strongly associated with various psychological factors. Comprehensive assessment of the physical and mental functioning of patients with CNP can improve the management and care of these patients.

  8. Insulin-like growth factors in endometrioid adenocarcinoma: Correlation with clinico-pathological features and estrogen receptor expression

    International Nuclear Information System (INIS)

    Liang, Yuan-Jiao; Hao, Qun; Zhang, Hui-Ming; Wu, Yuan-Zhe; Wang, Jian-Dong

    2012-01-01

    Endometrial carcinoma is a common malignancy of female genital tract. Insulin-like growth factor is known to elicit estrogen-induced mitogenic activity and anti-apoptotic effect in endometrial tissues. The retrospective study investigated the expression of insulin-like growth factors, estrogen receptors and their associations in endometrioid adenocarcinoma (EAC) from 80 EAC patients in immunohistochemistry, and 58 EAC patients and 42 control patients in quantitative RT-PCR. The Pearson correlation analysis was used to analyze their correlations with clinic-pathological parameters. Our results showed that insulin-like growth factor-1 and insulin-like growth factor-2 mRNA levels were higher in tumor tissues and tumor-adjacent tissues than those in control cells, and were inversely correlated with the malignancy of the tumor with a positive correlation with ERα and ERβ expression. Insulin-like growth factor-1R protein expression was correlated with clinical stage, and insulin-like growth factor-2R protein expression was inversely correlated with histological grade. Insulin-like growth factor system plays an important role in estrogen-induced endometrial carcinogenesis, and overexpression of insulin-like growth factor-1R in the advanced endometrioid adenocarcinoma is not estrogen-dependent

  9. Showing Area Matters: A Work of Friction

    Science.gov (United States)

    Van Domelen, David

    2010-01-01

    Typically, we teach the simplified friction equation of the form F[subscript s] = [mu][subscript s]N for static friction, where F[subscript s] is the maximum static friction, [mu][subscript s] is the coefficient of static friction, and "N" is the normal force pressing the surfaces together. However, this is a bit too simplified, and…

  10. A Pedagogical Model of Static Friction

    OpenAIRE

    Pickett, Galen T.

    2015-01-01

    While dry Coulombic friction is an elementary topic in any standard introductory course in mechanics, the critical distinction between the kinetic and static friction forces is something that is both hard to teach and to learn. In this paper, I describe a geometric model of static friction that may help introductory students to both understand and apply the Coulomb static friction approximation.

  11. Theoretical research on laminar friction resistance in tubes in rolling motion

    International Nuclear Information System (INIS)

    Yan Binghuo; Yu Lei; Yang Yanhua

    2010-01-01

    The model of laminar flow in tubes in rolling motion is established. The dimensionless correlation of velocity is derived, and the correlation of frictional resistance coefficient is also obtained. Of all the additional forces, only the tangential force effects on the flow. The effect of centrifugal and Coriolis forces on the flow is counteracted. The correlation of average frictional resistance coefficient is the same with that of no rolling motion. The effect of rolling motion on frictional resistance coefficient of laminar flow diminishes with the increase of Reynolds number. (authors)

  12. Calculation of the orientational linear and nonlinear correlation factors of polar liquids from the rotational Dean-Kawasaki equation

    Science.gov (United States)

    Déjardin, P. M.; Cornaton, Y.; Ghesquière, P.; Caliot, C.; Brouzet, R.

    2018-01-01

    A calculation of the Kirkwood and Piekara-Kielich correlation factors of polar liquids is presented using the forced rotational diffusion theory of Cugliandolo et al. [Phys. Rev. E 91, 032139 (2015)]. These correlation factors are obtained as a function of density and temperature. Our results compare reasonably well with the experimental temperature dependence of the linear dielectric constant of some simple polar liquids across a wide temperature range. A comparison of our results for the linear dielectric constant and the Kirkwood correlation factor with relevant numerical simulations of liquid water and methanol is given.

  13. Synergistic effect of tungsten disulfide and cenosphere combination on braking performance of composite friction materials

    International Nuclear Information System (INIS)

    Kachhap, Rakesh K.; Satapathy, Bhabani K.

    2014-01-01

    Graphical abstract: Graphical abstract showing correlation between enhanced frictional stability and enhanced visc-oelastic energy dissipation. - Highlights: • Developed new class of brake composites based on WS 2 and cenosphere. • Synergistic effect of WS 2 and cenosphere for enhanced friction stability. • Wear surface morphology revealed composition specific topography. • Friction fade-recovery performance remained optimal. - Abstract: Tungsten disulfide (WS 2 /TDS) based cenosphere (Cn) filled friction composites with varying cenosphere to WS 2 ratio (Cn/TDS) were fabricated by compression molding of phenolic resin based dry formulation mix and evaluated for their thermal, thermo-mechanical and tribological performances. The loss and revival of braking friction effectiveness due to heating or cooling of the disc termed as fade and recovery performance have been characterized on a Krauss friction testing machine following ECE R-90 industrial standards. The fade performance remained dependent on Cn/TDS, where enhanced fading could be correlated to lower Cn/TDS value accompanied with broader frictional fluctuations i.e. μ max –μ min . A decrease in the frictional-recovery response ensued with increase in Cn/TDS. Dynamic mechanical analysis revealed an increase in storage modulus till 2.5 wt.% of TDS loading followed by consistent decrease whereas two distinct peaks in loss modulus plots that are composition independent have been observed. Scanning electron microscopy revealed the worn surface morphology associated with the dynamics of contact patches formation and deformation vis-a-vis friction layer formation as integrally responsible for the observed friction performance. Energy dispersive analysis of X-rays (EDX) enabled compositional analysis of the friction layer viz. Fe, W, Si, and Al content which may have a mechanistic role in controlling phenomena like, disc rubbing, lubricity, porosity, and hardness of friction layer formed during braking

  14. Predicting tensile strength of friction stir welded AA6061 aluminium alloy joints by a mathematical model

    International Nuclear Information System (INIS)

    Elangovan, K.; Balasubramanian, V.; Babu, S.

    2009-01-01

    AA6061 aluminium alloy (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to weight ratio and good corrosion resistance. Compared to the fusion welding processes that are routinely used for joining structural aluminium alloys, friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. This process uses a non-consumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force etc., and tool pin profile play a major role in deciding the joint strength. An attempt has been made to develop a mathematical model to predict tensile strength of the friction stir welded AA6061 aluminium alloy by incorporating FSW process parameters. Four factors, five levels central composite design has been used to minimize number of experimental conditions. Response surface method (RSM) has been used to develop the model. Statistical tools such as analysis of variance (ANOVA), student's t-test, correlation co-efficient etc. have been used to validate the developed model. The developed mathematical model can be effectively used to predict the tensile strength of FSW joints at 95% confidence level

  15. Genetic vs Environmental Factors That Correlate With Rosacea: A Cohort-Based Survey of Twins.

    Science.gov (United States)

    Aldrich, Nely; Gerstenblith, Meg; Fu, Pingfu; Tuttle, Marie S; Varma, Priya; Gotow, Erica; Cooper, Kevin D; Mann, Margaret; Popkin, Daniel L

    2015-11-01

    To our knowledge, this is the first study on rosacea to formally define genetic and environmental contributions. To study a cohort of identical and fraternal twins to determine whether genetic factors contribute to rosacea development and, if genetic factors are present, quantitatively estimate the genetic contribution, as well as to identify environmental factors that correlate with rosacea by controlling for genetic susceptibility. Identical and fraternal twins were surveyed regarding risk factors implicated in rosacea. Faculty dermatologists determined a rosacea score for each twin participant according to the National Rosacea Society (NRS) grading system. Data were collected at the annual Twins Days Festival in Twinsburg, Ohio, on August 4-5, 2012, and August 2-3, 2013. Analysis was conducted for several months after each meeting. A cohort of 550 twin individuals, with most from Ohio, Pennsylvania, and the northeastern United States, participated. The NRS score and rosacea subtype were assessed using the NRS grading system and physical examination by board-certified dermatologists. Among the 275 twin pairs (550 individuals), there were 233 identical twin pairs with a mean rosacea score of 2.46 and 42 fraternal twin pairs with a mean rosacea score of 0.75. We observed a higher association of NRS scores between identical vs fraternal twins (r = 0.69 vs r = 0.46; P = .04), demonstrating a genetic contribution. Using the ACE model (proportion of variance in a trait heritable secondary to additive genetics [A] vs the proportions due to a common environment [C] and unique environment [E]), we calculated this genetic contribution to be 46%. A higher NRS score was also significantly associated with the following factors: age (r = 0.38; P rosacea. We found that approximately half of the contribution to the NRS score could be accounted for by genetics and the other half by environment. We identified correlations between rosacea and UV radiation exposure

  16. Friction Material Composites Materials Perspective

    CERN Document Server

    Sundarkrishnaa, K L

    2012-01-01

    Friction Material Composites is the first of the five volumes which strongly educates and updates engineers and other professionals in braking industries, research and test labs. It explains besides the formulation of design processes and its complete manufacturing input. This book gives an idea of mechanisms of friction and how to control them by designing .The book is  useful for designers  of automotive, rail and aero industries for designing the brake systems effectively with the integration of friction material composite design which is critical. It clearly  emphasizes the driving  safety and how serious designers should  select the design input. The significance of friction material component like brake pad or a liner as an integral part of the brake system of vehicles is explained. AFM pictures at nanolevel illustrate broadly the explanations given.

  17. Size scaling of static friction.

    Science.gov (United States)

    Braun, O M; Manini, Nicola; Tosatti, Erio

    2013-02-22

    Sliding friction across a thin soft lubricant film typically occurs by stick slip, the lubricant fully solidifying at stick, yielding and flowing at slip. The static friction force per unit area preceding slip is known from molecular dynamics (MD) simulations to decrease with increasing contact area. That makes the large-size fate of stick slip unclear and unknown; its possible vanishing is important as it would herald smooth sliding with a dramatic drop of kinetic friction at large size. Here we formulate a scaling law of the static friction force, which for a soft lubricant is predicted to decrease as f(m)+Δf/A(γ) for increasing contact area A, with γ>0. Our main finding is that the value of f(m), controlling the survival of stick slip at large size, can be evaluated by simulations of comparably small size. MD simulations of soft lubricant sliding are presented, which verify this theory.

  18. Correlation of clinical, endoscopic, and histological findings with virulence factors in children with Helicobacter pylori gastritis.

    Science.gov (United States)

    Selimoglu, Mukadder A; Karabiber, Hamza; Otlu, Baris; Yildirim, Ozge; Özer, Ali; Samdanci, Emine

    2014-06-01

    As there are limited data regarding the correlation between virulence factors and clinical, endoscopic, and histological findings in children with Helicobacter pylori gastritis, we aimed to evaluate that probable relationship in pediatric cases. One hundred and fifty-nine children with chronic abdominal pain or dyspepsia were included in this study. Upper gastrointestinal endoscopy was performed and multiple biopsy samples were taken from the esophagus, the antrum, and the duodenum. PCR was used for the determination of virulence factors. According to PCR analysis, 98 (61.6%) children were positive for H. pylori. Using histopathological examination and culture, H. pylori was detected in 65 (40.9%) and 51 (32.1%) children, respectively. Peptic ulcer prevalence and histopathological features were not different among cagA, cagE, or iceA1 positive and negative groups (P>0.05). Peptic ulcer prevalence and histopathological findings were more common in iceA2-positive patients (P0.05). S1b positivity was associated with a higher esophagitis rate (P<0.05). Among virulence factors, iceA2 was associated with peptic ulcer and milder histopathological findings, and vacAs1 was associated with milder histopathological findings.

  19. Prevalence of Painful Temporomandibular Disorders and Correlation to Lifestyle Factors among Adolescents in Norway

    Directory of Open Access Journals (Sweden)

    Vegard Østensjø

    2017-01-01

    Full Text Available Aim. To estimate the prevalence of painful temporomandibular disorders (TMD-P among adolescents and to investigate correlations with health, environment, and lifestyle factors. Methods. For this cross-sectional case-control study, 562 patients were consecutively recruited at their yearly revision control from four dental clinics in Rogaland County, Norway. Patients completed a questionnaire on general health, socioeconomics, demographics, and lifestyle factors. Responses to two screening questions identified patients with TMD-P, who then underwent clinical examination to verify the TMD diagnosis. Pain intensity was assessed on a visual analogue scale. Patients without TMD-P constituted the control group and were not clinically examined. Results. 7% experienced TMD-P. The female-to-male ratio is 3:1; median age is 17 years. Patients at urban clinics had higher prevalence compared with those at rural clinics. TMD-P patients had headache and severe menstrual pain compared to controls. They were more likely to live with divorced/single parents and less likely to have regular physical activity. Myalgia was present in 21 patients with TMD-P, arthralgia in nine, and myalgia and arthralgia in nine. Females had higher pain intensity than males. Conclusions. A low prevalence of TMD-P was shown but was comparable to other studies. Sex, health, lifestyle, and environment factors were associated with TMD-P.

  20. Peak power factor determination of the RA-6 Argentinean Research Reactor using measurement-calculations correlations

    International Nuclear Information System (INIS)

    Sanchez, F. A.; Blaumann, H.; Lopasso, E.; Longhino, J

    2009-01-01

    The maximum power of a reactor is limited by the power peaking factor. During the design stage it is calculated with neutronic calculation codes. This is not enough for ensuring its value due to modelling approximations. For the RA-6s low enrichment new core a calculus-measurement correlation method have been applied. Position and magnitude of the maximum power density estimated by calculus are used by this method. For this work 249 cooper-gold alloy (1.55% Au) wires have been distributed along the core using 19 aluminium blades. Their positions have been selected using information given by a 5 groups PUMA reactor model. Wire s activity have been measured with a HPGe detector. Gold activity have been used only for verifying the calculated core spectrum. The measured power peaking factor was 2.48±0.3 (3σ), 15% above the calculated value. About 97% of measured points had less than 20% calculation-measurement difference and about 80% had less than 10%. The power peaking factor determined by this method consolidates also the calculations models. [es

  1. Dysregulation of Elongation Factor 1A Expression is Correlated with Synaptic Plasticity Impairments in Alzheimer's Disease.

    Science.gov (United States)

    Beckelman, Brenna C; Day, Stephen; Zhou, Xueyan; Donohue, Maggie; Gouras, Gunnar K; Klann, Eric; Keene, C Dirk; Ma, Tao

    2016-09-06

    Synaptic dysfunction may represent an early and crucial pathophysiology in Alzheimer's disease (AD). Recent studies implicate a connection between synaptic plasticity deficits and compromised capacity of de novo protein synthesis in AD. The mRNA translational factor eukaryotic elongation factor 1A (eEF1A) is critically involved in several forms of long-lasting synaptic plasticity. By examining postmortem human brain samples, a transgenic mouse model, and application of synthetic human Aβ42 on mouse hippocampal slices, we demonstrated that eEF1A protein levels were significantly decreased in AD, particularly in the hippocampus. In contrast, brain levels of eukaryotic elongation factor 2 were unaltered in AD. Further, upregulation of eEF1A expression by the adenylyl cyclase activator forskolin, which induces long-lasting synaptic plasticity, was blunted in hippocampal slices derived from Tg2576 AD model mice. Finally, Aβ-induced hippocampal long-term potentiation defects were alleviated by upregulation of eEF1A signaling via brain-specific knockdown of the gene encoding tuberous sclerosis 2. In summary, our findings suggest a strong correlation between the dysregulation of eEF1A synthesis and AD-associated synaptic failure. These findings provide insights into the understanding of molecular mechanisms underlying AD etiology and may aid in identification of novel biomarkers and therapeutic targets.

  2. Rubber friction: comparison of theory with experiment.

    Science.gov (United States)

    Lorenz, B; Persson, B N J; Dieluweit, S; Tada, T

    2011-12-01

    We have measured the friction force acting on a rubber block slid on a concrete surface. We used both unfilled and filled (with carbon black) styrene butadiene (SB) rubber and have varied the temperature from -10 °C to 100 °C and the sliding velocity from 1 μm/s to 1000 μm/s. We find that the experimental data at different temperatures can be shifted into a smooth master-curve, using the temperature-frequency shifting factors obtained from measurements of the bulk viscoelastic modulus. The experimental data has been analyzed using a theory which takes into account the contributions to the friction from both the substrate asperity-induced viscoelastic deformations of the rubber, and from shearing the area of real contact. For filled SB rubber the frictional shear stress σ(f) in the area of real contact results mainly from the energy dissipation at the opening crack on the exit side of the rubber-asperity contact regions. For unfilled rubber we instead attribute σ(f) to shearing of a thin rubber smear film, which is deposited on the concrete surface during run in. We observe very different rubber wear processes for filled and unfilled SB rubber, which is consistent with the different frictional processes. Thus, the wear of filled SB rubber results in micrometer-sized rubber particles which accumulate as dry dust, which is easily removed by blowing air on the concrete surface. This wear process seams to occur at a steady rate. For unfilled rubber a smear film forms on the concrete surface, which cannot be removed even using a high-pressure air stream. In this case the wear rate appears to slow down after some run in time period.

  3. Concentration of Glial Cell Line-Derived Neurotrophic Factor Positively Correlates with Symptoms in Functional Dyspepsia.

    Science.gov (United States)

    Tanaka, Fumio; Tominaga, Kazunari; Fujikawa, Yoshiko; Nagami, Yasuaki; Kamata, Noriko; Yamagami, Hirokazu; Tanigawa, Tetsuya; Shiba, Masatsugu; Watanabe, Toshio; Fujiwara, Yasuhiro; Arakawa, Tetsuo

    2016-12-01

    In patients with functional dyspepsia (FD), mild duodenal inflammation correlates with increased mucosal permeability. Enteric glial cells can produce glial cell line-derived neurotrophic factor (GDNF) to repair disrupted epithelial barrier function. We examined the role of duodenal GDNF in FD pathophysiology and its association with dyspeptic symptoms. Duodenal biopsies taken from FD patients and control subjects were used for analysis. GDNF protein expression and localization were examined. Cellular infiltration of eosinophils and mast cells was measured. We also examined the intercellular space between the adjacent epithelial cells at the apical junction complex using transmission electron microscopy. In FD patients, expression of GDNF protein was significantly increased compared with controls, 107.3 (95.3-136.7) versus 49.3 (38.0-72.6) pg/mg protein (median (interquartile range), p = 0.006), respectively. GDNF was localized in enteric glial cells, eosinophils, and epithelial cells. The number of eosinophils was significantly greater in FD patients than in controls, 1039 (923-1181) versus 553 (479-598) cells/mm 2 (p = 0.021), respectively. The intercellular space was dilated at the adherent junction in FD patients compared to control patients, 32.4 (29.8-34.8) versus 22.0 (19.9-26.1) nm (p = 0.002), respectively. Intercellular distance positively correlated with the frequency of postprandial fullness and early satiation (p = 0.001, r = 0.837 and p = 0.009, r = 0.693, respectively). Expression of GDNF correlated with epigastric burning (p = 0.041, r = 0.552). Increased expression of duodenal GDNF might be involved in FD pathophysiology and symptom perception.

  4. CORRELATION OF CLINICAL AND PROGNOSTIC FACTORS, WHIT THE P53PROTEIN EXPRESSION IN INVASIVE CERVICAL CARCINOMA

    Directory of Open Access Journals (Sweden)

    Lúcia Teresa Hinojosa Schäffer

    2012-06-01

    Full Text Available The analysis of p53 protein in cervical carcinoma correlated with clinical and prognostic factors was performed in a retrospective study with p53 expression detection by immunohistochemical technique. 120 slides of patients with squamous cell cancer at the Gynecologic Oncology Clinic and stored in the Department of Pathological Anatom at the School of Medicine of Botucatu were used. Age, ethnicity, parity, smoking habit, oral contraceptive use, age at first intercourse, histology, stage, treatment, and follow-up were the cofactors associated with p53 positivity. Fisher’s exact tests were carried out to analyze associations between p53 and variables, with p < 0.05 as the significant level. The study revealed a 43.3% frequency of patients with stage II disease and p53 positive rate with p = 0.001, and 64.2% frequency with p = 0.024 of Correlação de fatores clínicos e prognósticos proteína p53 no colo uterino. patients whose first intercourse occurred between the ages of 15 and 20. These findings show the correlation between stage II disease and age at fir st intercourse with p53 positive in invasive cervical cancer. Fisher's exact test revelead these cofactors to be statistically significant and there was no association between the protein p53 with others prognostic and analyzed cofactors. The prognostic value of p53 in cervical cancer had been examined, with the conclusion that p53 is correlated to unfavorable prognosis.

  5. Correlation between chlorophyll-a and related environmental factors based on Copula in Chaohu Lake, China

    Science.gov (United States)

    Ma, Huiqun; Wang, Yong

    2018-01-01

    Chlorophyll-a is crucial to characterize the eutrophication status. Return period of Chlorophyll-a is very helpful to the treatment of lakes and reservoirs eutrophication. In this study, the Gumbel-Hougaard Copula method is applied to discern the inherent relationship between chlorophyll-a and environmental variables of Chaohu Lake, China. The result shows that Weibull probability distribution is the preferred marginal distribution for Chl-a, Gamma for TP and TN, Log-normal for SD and CODmn. The sequence of correlation between chlorophyll-a and environmental factors is CODmn, SD, TP and TN. The method proposed here presents an effective tool to analyze the interaction of eutrophic variables in complex water environment system, also could provide reference for integrated management and treatment of lakes and reservoirs.

  6. White matter deficits in psychopathic offenders and correlation with factor structure.

    Directory of Open Access Journals (Sweden)

    Sylco S Hoppenbrouwers

    Full Text Available Psychopathic offenders show a persistent pattern of emotional unresponsivity to the often horrendous crimes they perpetrate. Recent studies have related psychopathy to alterations in white matter. Therefore, diffusion tensor imaging followed by tract-based spatial statistics (TBSS analysis in 11 psychopathic offenders matched to 11 healthy controls was completed. Fractional anisotropy was calculated within each voxel and comparisons were made between groups using a permutation test. Any clusters of white matter voxels different between groups were submitted to probabilistic tractography. Significant differences in fractional anisotropy were found between psychopathic offenders and healthy controls in three main white matter clusters. These three clusters represented two major networks: an amygdalo-prefrontal network, and a striato-thalamo-frontal network. The interpersonal/affective component of the PCL-R correlated with white matter deficits in the orbitofrontal cortex and frontal pole whereas the antisocial component correlated with deficits in the striato-thalamo-frontal network. In addition to replicating earlier work concerning disruption of an amygdala-prefrontal network, we show for the first time that white matter integrity in a striato-thalamo-frontal network is disrupted in psychopathic offenders. The novelty of our findings lies in the two dissociable white matter networks that map directly onto the two major factors of psychopathy.

  7. Radiogenomic correlation in lung adenocarcinoma with epidermal growth factor receptor mutations: Imaging features and histological subtypes

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Su Jin [Seoul National University Bundang Hospital, Department of Radiology, Seongnam-si, Gyeonggi-do (Korea, Republic of); Hanyang University, Department of Radiology, School of Medicine, Seoul (Korea, Republic of); Kim, Tae Jung [Seoul National University Bundang Hospital, Department of Radiology, Seongnam-si, Gyeonggi-do (Korea, Republic of); Samsung Medical Center, Department of Radiology, Seoul (Korea, Republic of); Choi, Yo Won [Hanyang University, Department of Radiology, School of Medicine, Seoul (Korea, Republic of); Park, Jeong-Soo [Dankook Universicity, Department of Biochemistry, College of Medicine, Cheonan (Korea, Republic of); Chung, Jin-Haeng [Seoul National University Bundang Hospital, Department of Pathology, Seongnam-si, Gyeonggi-do (Korea, Republic of); Lee, Kyung Won [Seoul National University Bundang Hospital, Department of Radiology, Seongnam-si, Gyeonggi-do (Korea, Republic of)

    2016-10-15

    To correlate imaging features of resected lung adenocarcinoma with epidermal growth factor receptor (EGFR) mutation and the IASLC/ATS/ERS classification histological subtypes. In 250 consecutive patients with resected lung adenocarcinoma, EGFR mutation status was correlated with demographics, imaging features including ground-glass opacity (GGO) proportion and the IASLC/ATS/ERS classification histological subtypes. EGFR mutations were significantly more frequent in women (54.5 % vs. 38.1 %, p = 0.011) and in never-smokers (54.7 % vs. 35.3 %, p = 0.003). GGO proportion was significantly higher in tumours with EGFR mutation than in those without (30.3 ± 33.8 % vs. 19.0 ± 29.3 %, p = 0.005). EGFR mutation was significantly more frequent in tumours with GGO ≥ 50 % and tumours with any GGO (p = 0.026 and 0.008, respectively). Adenocarcinomas with exon 19 or 21 mutation showed significantly higher GGO proportion than that in EGFR wild-type tumours (p = 0.009 and 0.029, respectively). Absence of GGO was an independent predictor of negative EGFR mutation (odds ratio, 1.81; 95 % confidence interval, 1.16-3.04; p = 0.018). GGO proportion in adenocarcinomas with EGFR mutation was significantly higher than that in EGFR wild-type tumours, and the absence of GGO on CT was an independent predictor of negative EGFR mutation. (orig.)

  8. Brain-derived neurotrophic factor correlated with muscle strength in subjects undergoing stationary bicycle exercise training.

    Science.gov (United States)

    Tsai, Sen-Wei; Chan, Yin-Ching; Liang, Francois; Hsu, Chiann-Yi; Lee, I-Te

    2015-04-01

    Several central nervous disorders are associated with metabolic syndrome (MetS) and type 2 diabetes. Reduction in brain-derived neurotrophic factor (BDNF) is involved in the mechanism of central nervous dysfunction. BDNF is up-regulated after exercise, but it is not known whether increased BDNF is related to increases in muscle strength. In the present study, subjects with MetS or type 2 diabetes were enrolled in an exercise program. All participants underwent an indoor bicycle exercise program for twelve weeks. Serum BDNF was determined after overnight fasting. Muscle strength was assessed by extension of the dominant lower extremity. A total of 33 subjects were enrolled in this study. The body mass index did not change significantly (from 30.4±6.0 to 30.2±5.8kg/m(2), P=0.436), but serum BDNF increased significantly (from 17.1±9.1 to 24.2±10.7ng/mL, Pexercise-associated BDNF was significantly correlated with the increased strength in lower-extremity extension test (r=0.54, P=0.001). Using multivariate regression analysis, muscle-strength increment, but not body-weight change, was an independent factor for serum BDNF (95% CI=0.009-0.044, P=0.005). After a twelve-week program of stationary bicycle exercise, serum BDNF concentration increased, and this change was positively correlated with muscle strength of lower-extremity extension, but not body weight. ( NCT02268292, ClinicalTrials.gov). Copyright © 2015 Elsevier Inc. All rights reserved.

  9. The Indeterminate Case of Classical Static Friction When Coupled with Tension

    Science.gov (United States)

    Hahn, Kenneth D.; Russell, Jacob M.

    2018-02-01

    It has been noted that the static friction force poses challenges for students and, at times, even their instructors. Unlike the gravitational force, which has a precise and unambiguous magnitude (FG = mg), the magnitude and direction of the static friction force depend on other forces at play. Friction can be understood rather well in terms of complicated atomic-scale interactions between surfaces. Ringlein and Robbins survey aspects of the atomic origins of friction, and Folkerts explores factors that affect the value of static friction. However, what students typically encounter in an introductory course ignores the atomic origins of friction (beyond perhaps a brief overview of the atomic model). The rules of dry friction (i.e., non-lubricated surfaces in contact) taught in introductory physics were originally published in 1699 by Guillaume Amontons. Amontons's first law states that the force of friction is directly proportional to the applied load, i.e., f = μFN, where FN is the normal force and μ is the coefficient of friction. His second law states that the force of friction is independent of the macroscopic area of contact. These laws were verified by Coulomb in 1781.

  10. Influence of roughness parameters on coefficient of friction under ...

    Indian Academy of Sciences (India)

    Fourier Transform Infrared spectroscopy technique. For a given surface texture, the ... Figure 3 shows the results of the correlation analysis between surface roughness parameters and coefficient of friction under ... ious roughness parameters the plowing component is controlled by the roughness parameter,. Del a. Table 2.

  11. [Retrospective analysis of correlative factors between digestive system injury and anticoagulant or antiplatelet-agents].

    Science.gov (United States)

    Cui, Ning; Luo, Hesheng

    2014-05-27

    To explore the correlative factors and clinical characteristics of digestive system injury during the treatment of anticoagulant and (or) antiplatelet-agents. A total of 1 443 hospitalized patients on anticoagulant and (or) antiplatelet-agents from January 2010 to December 2013 at Renmin Hospital of Wuhan University were analyzed retrospectively. Their length of hospital stay was from 5 to 27 days. Most of them were elderly males (n = 880, 61.0%) with an average age of (62 ± 6) years. 1 138 patients (78.9%) were farmers, workers or someone without a specific occupation. During the treatment of anticoagulant/antiplatelet-agents, statistical difference existed (P = 0.01) between positively and negatively previous digestive disease groups for actively newly occurring digestive system injury (16.0% (41/256) vs 15.9% (189/1 187)). After the dosing of anticoagulant and (or) antiplatelet-agents, 57 (66.3%, 57/86) patients were complicated by hemorrhage of digestive tract, taking 62.9% (61/97) of all positive result patients for Helicobacter pylori test. Comparing preventive PPI group with no PPI group, there was no marked statistical differences (P = 2.67) for digestive system complication (including hemorrhage of digestive tract) while receiving anticoagulant and (or) antiplatelet-agents (13.9% (74/533) vs 17.1% (156/910)). During anticoagulant and/or antiplatelet-agent therapy, 185 patients (12.8%) were complicated by peptic ulcer or peptic ulcer with bleeding, 40 patients (2.8%) had erosive gastritis and 5 (0.3%) developed acute gastric mucosal lesions. And 42 of 76 patients complicated by hemorrhage of digestive tract underwent endoscopic hemostasis while 2 patients were operated. Ninety-seven patients (6.7%) died, including 61 (62.9%, 61/97) from hemorrhage of digestive tract. The remainder became cured, improved and discharged. Moreover, no significant statistical differences existed (P = 2.29) among three combination group (aspirin, clopidogrel, warfarin), two

  12. Friction and stress coupling on the subduction interfaces

    Science.gov (United States)

    Tan, E.; Lavier, L.; van Avendonk, H.

    2011-12-01

    At a subduction zone, the down-going oceanic plate slides underneath the overriding plate. The frictional resistance to the relative motion between the plates generates great earthquakes along the subduction interface, which can cause tremendous damage in the civil life and property. There is a strong incentive to understand the frictional strength of the subduction interface. One fundamental question of mechanics of subuction is the degree of coupling between the plates, which is linked to the size of earthquakes. It has been noted that the trench-parallel (along-strike) gravity variation correlates positively with the trench-parallel topography anomaly and negatively with the activity of great earthquake (Song and Simons, 2003). Regions with a negative trench-parallel gravity anomaly are more likely to have great earthquakes. The interpretation of such correlation is that strong coupling along subduction interface will drag down the for-arc region of the overriding plate, which generates the gravity and topography anomalies, and could store more strain energy to be released during a great earthquake. We developed a 2D numerical thermo-mechanical code for modeling subduction. The numerical method is based on an explicit finite element method similar to the Fast Lagrangian Analysis of Continua (FLAC) technique. The constitutive law is visco-elasti-plastic with strain weakening. The cohesion and friction angle are reduced with increasing plastic strain after yielding. To track different petrologic phases, Lagrangian particles are distributed in the domain. Basalt-eclogite, sediment-schist and peridotite-serpentinite phase changes are included in the model. Our numerical models show that the degree of coupling negatively correlates with the coefficient of friction. In the low friction case, the subduction interface has very shallow dipping angle, which helps to elastically couple the downing plate with the overriding plate. The topography and gravity anomalies of the

  13. Correlation between CT perfusion parameters and microvessel density and vascular endothelial growth factor in adrenal tumors.

    Directory of Open Access Journals (Sweden)

    Hai-yan Qin

    Full Text Available We evaluated the correlation between computed tomography (CT perfusion parameters and markers of angiogenesis in adrenal adenomas and non-adenomas to determine if perfusion CT can be used to distinguish between them. Thirty-four patients with pathologically-confirmed adrenal tumors (17 adenomas, 17 non-adenomas received CT perfusion imaging before surgery. CT perfusion parameters (blood flow [BF], blood volume [BV], mean transit time [MTT], and permeability surface area product [PS] were calculated. Tumor tissue sections were examined with immunohistochemical methods for vascular endothelial growth factor (VEGF expression and microvessel density (MVD. The mean age of the 34 patients was 43 years. The median BV was significantly higher in adenomas than in non-adenomas [12.3 ml/100 g, inter-quartile range (IQR: 10.4 to 16.5 ml/100 g vs. 8.8 ml/100 g, IQR: 3.3 to 9.4 ml/100 g, p=0.001]. Differences in BF, MTT, and PS parameter values between adenomas and non-adenomas were not significant (p>0.05. The mean MVD was significantly higher in adenomas compared to non-adenomas (98.5 ± 28.5 vs. 53.5 ± 27.0, p<0.0001. Adenomas also expressed significantly higher median VEGF than non-adenomas (65%, IQR: 50 to 79% vs. 45%, IQR: 35 to 67%, p=0.02. A moderately strong correlation between BF and VEGF (r=0.53, p=0.03 and between BV and MVD among adenomas (r=0.57, p=0.02 exist. Morphology, MVD, and VEGF expression in adenomas differ significantly from non-adenomas. Of the CT perfusion parameters examined, both BF and BV correlate with MVD, but only BF correlates with VEGF, and only in adenomas. The significant difference in BV suggests that BV may be used to differentiate adenomas from non-adenomas. However, the small difference in BV shows that it may only be possible to use BV to identify adenomas vs. non-adenomas at extreme BV values.

  14. Stiffness of frictional contact of dissimilar elastic solids

    Science.gov (United States)

    Lee, Jin Haeng; Gao, Yanfei; Bower, Allan F.; Xu, Haitao; Pharr, George M.

    2018-03-01

    The classic Sneddon relationship between the normal contact stiffness and the contact size is valid for axisymmetric, frictionless contact, in which the two contacting solids are approximated by elastic half-spaces. Deviation from this result critically affects the accuracy of the load and displacement sensing nanoindentation techniques. This paper gives a thorough numerical and analytical investigation of corrections needed to the Sneddon solution when finite Coulomb friction exists between an elastic half-space and a flat-ended rigid punch with circular or noncircular shape. Because of linearity of the Coulomb friction, the correction factor is found to be a function of the friction coefficient, Poisson's ratio, and the contact shape, but independent of the contact size. Two issues are of primary concern in the finite element simulations - adequacy of the mesh near the contact edge and the friction implementation methodology. Although the stick or slip zone sizes are quite different from the penalty or Lagrangian methods, the calculated contact stiffnesses are almost the same and may be considerably larger than those in Sneddon's solution. For circular punch contact, the numerical solutions agree remarkably well with a previous analytical solution. For non-circular punch contact, the results can be represented using the equivalence between the contact problem and bi-material fracture mechanics. The correction factor is found to be a product of that for the circular contact and a multiplicative factor that depends only on the shape of the punch but not on the friction coefficient or Poisson's ratio.

  15. Compound hierarchical correlated beta mixture with an application to cluster mouse transcription factor DNA binding data

    OpenAIRE

    Dai, Hongying; Charnigo, Richard

    2015-01-01

    Modeling correlation structures is a challenge in bioinformatics, especially when dealing with high throughput genomic data. A compound hierarchical correlated beta mixture (CBM) with an exchangeable correlation structure is proposed to cluster genetic vectors into mixture components. The correlation coefficient, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\u...

  16. Partition coefficients of organic compounds in lipid-water systems and correlations with fish bioconcentration factors

    Science.gov (United States)

    Chiou, C.T.

    1985-01-01

    Triolein-water partition coefficients (KtW) have been determined for 38 slightly water-soluble organic compounds, and their magnitudes have been compared with the corresponding octanol-water partition coefficients (KOW). In the absence of major solvent-solute interaction effects in the organic solvent phase, the conventional treatment (based on Raoult's law) predicts sharply lower partition coefficients for most of the solutes in triolein because of its considerably higher molecular weight, whereas the Flory-Huggins treatment predicts higher partition coefficients with triolein. The data are in much better agreement with the Flory-Huggins model. As expected from the similarity in the partition coefficients, the water solubility (which was previously found to be the major determinant of the KOW) is also the major determinant for the Ktw. When the published BCF values (bioconcentration factors) of organic compounds in fish are based on the lipid content rather than on total mass, they are approximately equal to the Ktw, which suggests at least near equilibrium for solute partitioning between water and fish lipid. The close correlation between Ktw and Kow suggests that Kow is also a good predictor for lipid-water partition coefficients and bioconcentration factors.

  17. Prediction of Sliding Friction Coefficient Based on a Novel Hybrid Molecular-Mechanical Model.

    Science.gov (United States)

    Zhang, Xiaogang; Zhang, Yali; Wang, Jianmei; Sheng, Chenxing; Li, Zhixiong

    2018-08-01

    Sliding friction is a complex phenomenon which arises from the mechanical and molecular interactions of asperities when examined in a microscale. To reveal and further understand the effects of micro scaled mechanical and molecular components of friction coefficient on overall frictional behavior, a hybrid molecular-mechanical model is developed to investigate the effects of main factors, including different loads and surface roughness values, on the sliding friction coefficient in a boundary lubrication condition. Numerical modelling was conducted using a deterministic contact model and based on the molecular-mechanical theory of friction. In the contact model, with given external loads and surface topographies, the pressure distribution, real contact area, and elastic/plastic deformation of each single asperity contact were calculated. Then asperity friction coefficient was predicted by the sum of mechanical and molecular components of friction coefficient. The mechanical component was mainly determined by the contact width and elastic/plastic deformation, and the molecular component was estimated as a function of the contact area and interfacial shear stress. Numerical results were compared with experimental results and a good agreement was obtained. The model was then used to predict friction coefficients in different operating and surface conditions. Numerical results explain why applied load has a minimum effect on the friction coefficients. They also provide insight into the effect of surface roughness on the mechanical and molecular components of friction coefficients. It is revealed that the mechanical component dominates the friction coefficient when the surface roughness is large (Rq > 0.2 μm), while the friction coefficient is mainly determined by the molecular component when the surface is relatively smooth (Rq friction coefficient are recommended.

  18. High speed friction microscopy and nanoscale friction coefficient mapping

    International Nuclear Information System (INIS)

    Bosse, James L; Lee, Sungjun; Huey, Bryan D; Andersen, Andreas Sø; Sutherland, Duncan S

    2014-01-01

    As mechanical devices in the nano/micro length scale are increasingly employed, it is crucial to understand nanoscale friction and wear especially at technically relevant sliding velocities. Accordingly, a novel technique has been developed for friction coefficient mapping (FCM), leveraging recent advances in high speed AFM. The technique efficiently acquires friction versus force curves based on a sequence of images at a single location, each with incrementally lower loads. As a result, true maps of the coefficient of friction can be uniquely calculated for heterogeneous surfaces. These parameters are determined at a scan velocity as fast as 2 mm s −1 for microfabricated SiO 2 mesas and Au coated pits, yielding results that are identical to traditional speed measurements despite being ∼1000 times faster. To demonstrate the upper limit of sliding velocity for the custom setup, the friction properties of mica are reported from 200 µm s −1 up to 2 cm s −1 . While FCM is applicable to any AFM and scanning speed, quantitative nanotribology investigations of heterogeneous sliding or rolling components are therefore uniquely possible, even at realistic velocities for devices such as MEMS, biological implants, or data storage systems. (paper)

  19. Mechanism of sliding friction on a film-terminated fibrillar interface.

    Science.gov (United States)

    Shen, Lulin; Jagota, Anand; Hui, Chung-Yuen

    2009-03-03

    We study the mechanism of sliding friction on a film-terminated fibrillar interface. It has been shown that static friction increases significantly with increasing spacing between fibrils, and with increasing rate of loading. However, surprisingly, the sliding friction remains substantially unaffected both by geometry and by the rate of loading. The presence of the thin terminal film is a controlling factor in determining the sliding friction. Experimentally, and by a simple model in which the indenter is held up by the tension in the thin film, we show how the indenter maintains a nearly constant contact area that is independent of the fibril spacing, resulting in constant sliding friction. By this mechanism, using the film-terminated structure, one can enhance the static friction without affecting the sliding behavior.

  20. Determination and Application of Comprehensive Specific Frictional Resistance in Heating Engineering

    Directory of Open Access Journals (Sweden)

    Yanan Tian

    2018-01-01

    Full Text Available In this study, we analyze the deficiencies of specific frictional resistance in heating engineering. Based on economic specific frictional resistance, we put forward the concept of comprehensive specific frictional resistance, which considers the multiple factors of technology, economy, regulation modes, pipe segment differences, and medium pressure. Then, we establish a mathematical model of a heating network across its lifespan in order to develop a method for determining the comprehensive specific frictional resistance. Relevant conclusions can be drawn from the results. As an application, we have planned the heating engineering for Yangyuan County in China, which demonstrates the feasibility and superiority of the method.

  1. Motion of a thin elliptic plate under symmetric and asymmetric orthotropic friction forces

    Science.gov (United States)

    Silantyeva, O.; Dmitriev, N.

    2018-03-01

    The anisotropy of a friction force is proved to be an important factor in various contact problems. We study the dynamical behavior of thin plates with respect to symmetric and asymmetric orthotropic friction. The terminal motion of plates with circular and elliptic contact areas is analyzed. The evaluation of friction forces for both symmetric and asymmetric orthotropic cases is shown using an analytic approach. Regular pressure distribution is considered. Differential equations are formulated and solved numerically for a number of initial conditions. The method used gives more accurate results compared to the previous study. Examples show the significant influence of friction force asymmetry on motion.

  2. Factor structure and correlates of the acceptance of cosmetic surgery scale among South Korean university students.

    Science.gov (United States)

    Swami, Viren; Hwang, Choon-Sup; Jung, Jaehee

    2012-02-01

    Research on the acceptance of cosmetic surgery has focused on relatively affluent Western samples, to the exclusion of non-Western samples and any potential cross-cultural differences. While rates of cosmetic surgery in South Korea have risen sharply in the past decade, mirroring rates in other East Asian nations, little is known about attitudes toward cosmetic surgery in the Korean population. To examine the factor structure and correlates of a Korean adaptation of the previously-published Acceptance of Cosmetic Surgery Scale (ACSS). South Korean university students (N = 267) completed the ACSS, as well as included Korean translations of measures for actual vs. ideal body weight discrepancy, body appreciation, sociocultural attitudes toward appearance, and demographics. The Korean ACSS reduced to a two-factor solution, mirroring results among other non-Western samples, although a one-factor solution was deemed more plausible. Compared to men, women had significantly higher total scores, suggesting that they were more accepting of cosmetic surgery. A multiple regression showed that, after controlling for the effects of participant sex, the only significant predictor of acceptance of cosmetic surgery was general body appreciation, suggesting that some may view cosmetic surgery as a means of enhancing their body image. The results reveal important global information for plastic surgeons-not only on the treatment of non-Western patients but on the South Korean market, in which the cosmetic surgery industry remains unregulated. Given the popularity and acceptance of cosmetic surgery in South Korea, there is an urgent need for regulatory intervention to ensure patient safety and satisfaction.

  3. Very High Cycle Fatigue Crack Initiation Mechanism in Nugget Zone of AA 7075 Friction Stir Welded Joint

    Directory of Open Access Journals (Sweden)

    Chao He

    2017-01-01

    Full Text Available Very high cycle fatigue behavior of nugget zone in AA 7075 friction stir welded joint was experimentally investigated using ultrasonic fatigue testing system (20 kHz to clarify the crack initiation mechanism. It was found that the fatigue strength of nugget zone decreased continuously even beyond 107 cycles with no traditional fatigue limits. Fatigue cracks initiated from the welding defects located at the bottom side of the friction stir weld. Moreover, a special semicircular zone could be characterized around the crack initiation site, of which the stress intensity factor approximately equaled the threshold of fatigue crack propagation rate. Finally, a simplified model was proposed to estimate the fatigue life by correlating the welding defect size and applied stress. The predicted results are in good agreement with the experimental results.

  4. An eight-legged tactile sensor to estimate coefficient of static friction.

    Science.gov (United States)

    Wei Chen; Rodpongpun, Sura; Luo, William; Isaacson, Nathan; Kark, Lauren; Khamis, Heba; Redmond, Stephen J

    2015-08-01

    It is well known that a tangential force larger than the maximum static friction force is required to initiate the sliding motion between two objects, which is governed by a material constant called the coefficient of static friction. Therefore, knowing the coefficient of static friction is of great importance for robot grippers which wish to maintain a stable and precise grip on an object during various manipulation tasks. Importantly, it is most useful if grippers can estimate the coefficient of static friction without having to explicitly explore the object first, such as lifting the object and reducing the grip force until it slips. A novel eight-legged sensor, based on simplified theoretical principles of friction is presented here to estimate the coefficient of static friction between a planar surface and the prototype sensor. Each of the sensor's eight legs are straight and rigid, and oriented at a specified angle with respect to the vertical, allowing it to estimate one of five ranges (5 = 8/2 + 1) that the coefficient of static friction can occupy. The coefficient of friction can be estimated by determining whether the legs have slipped or not when pressed against a surface. The coefficients of static friction between the sensor and five different materials were estimated and compared to a measurement from traditional methods. A least-squares linear fit of the sensor estimated coefficient showed good correlation with the reference coefficient with a gradient close to one and an r(2) value greater than 0.9.

  5. Real-Time Dynamic Observation of Micro-Friction on the Contact Interface of Friction Lining

    Science.gov (United States)

    Zhang, Dekun; Chen, Kai; Guo, Yongbo

    2018-01-01

    This paper aims to investigate the microscopic friction mechanism based on in situ microscopic observation in order to record the deformation and contact situation of friction lining during the frictional process. The results show that friction coefficient increased with the shear deformation and energy loss of the surfacee, respectively. Furthermore, the friction mechanism mainly included adhesive friction in the high-pressure and high-speed conditions, whereas hysteresis friction was in the low-pressure and low-speed conditions. The mixed-friction mechanism was in the period when the working conditions varied from high pressure and speed to low pressure and speed. PMID:29498677

  6. Correlation Between Urine Macrophage Migration Inhibitory Factor (MIF/Creatinine Ratio and Time After Kidney Transplantation

    Directory of Open Access Journals (Sweden)

    Saeed Sabaghi

    2008-08-01

    Full Text Available Background:Despite the long-standing association of macrophage migration inhibitory factor (MIF with delayed-type hypersensitivity response,the potential role Of MIF in chronic allograft nephropathy is unknown.The association between upregulation of MIF expression, macrophage and T cell infiltration and the severity of chronic allograft nephropathy suggests that MIF may be an important mediator in the process of chronic allograft nephropathy.Therefore,the aims of this study were to measure urine concentration of MIF after renal transplantation,and to determine if it increases with time.  Methods: In this prospective cross-sectional study twenty-two pediatric patients   (case, group A who received kidney transplants between 1999 and 2006, and forty  healthy children (control, group B were recruited. Urine MIF and creatinine were  assessed in all patients.Urine MIF concentrations were quantitated by ELISA.Results: The mean ratios of urine MIF/Creatinine (Cr were calculated as 5.046(SEM=2.04 pg/μmol creatinine in transplanted-kidney patients (group A and 1.85(SEM=0.35 pg/μmol creatinine in healthy individuals(group B.Agood significant  correlation was seen between urine MIF/Cr ratio and time after kidney transplantation  in recipients (P=0.002, rSpearman = +0.633.  Conclusion: This study shows significant correlation between urine MIF/Cr ratio and time passed after transplantation. Increasing MIF/Cr ratios were seen in patients with a longer post transplantation period. Therefore, it is necessary to determine the  role of macrophages in chronic renal nephropathy especially chronic rejection with additive studies and then study the effect of anti-MIF antibodies in the treatment of this condition. 

  7. Versatile Friction Stir Welding/Friction Plug Welding System

    Science.gov (United States)

    Carter, Robert

    2006-01-01

    A proposed system of tooling, machinery, and control equipment would be capable of performing any of several friction stir welding (FSW) and friction plug welding (FPW) operations. These operations would include the following: Basic FSW; FSW with automated manipulation of the length of the pin tool in real time [the so-called auto-adjustable pin-tool (APT) capability]; Self-reacting FSW (SRFSW); SR-FSW with APT capability and/or real-time adjustment of the distance between the front and back shoulders; and Friction plug welding (FPW) [more specifically, friction push plug welding] or friction pull plug welding (FPPW) to close out the keyhole of, or to repair, an FSW or SR-FSW weld. Prior FSW and FPW systems have been capable of performing one or two of these operations, but none has thus far been capable of performing all of them. The proposed system would include a common tool that would have APT capability for both basic FSW and SR-FSW. Such a tool was described in Tool for Two Types of Friction Stir Welding (MFS- 31647-1), NASA Tech Briefs, Vol. 30, No. 10 (October 2006), page 70. Going beyond what was reported in the cited previous article, the common tool could be used in conjunction with a plug welding head to perform FPW or FPPW. Alternatively, the plug welding head could be integrated, along with the common tool, into a FSW head that would be capable of all of the aforementioned FSW and FPW operations. Any FSW or FPW operation could be performed under any combination of position and/or force control.

  8. Slow rupture of frictional interfaces

    Science.gov (United States)

    Bar Sinai, Yohai; Brener, Efim A.; Bouchbinder, Eran

    2012-02-01

    The failure of frictional interfaces and the spatiotemporal structures that accompany it are central to a wide range of geophysical, physical and engineering systems. Recent geophysical and laboratory observations indicated that interfacial failure can be mediated by slow slip rupture phenomena which are distinct from ordinary, earthquake-like, fast rupture. These discoveries have influenced the way we think about frictional motion, yet the nature and properties of slow rupture are not completely understood. We show that slow rupture is an intrinsic and robust property of simple non-monotonic rate-and-state friction laws. It is associated with a new velocity scale cmin, determined by the friction law, below which steady state rupture cannot propagate. We further show that rupture can occur in a continuum of states, spanning a wide range of velocities from cmin to elastic wave-speeds, and predict different properties for slow rupture and ordinary fast rupture. Our results are qualitatively consistent with recent high-resolution laboratory experiments and may provide a theoretical framework for understanding slow rupture phenomena along frictional interfaces.

  9. Level of evidence of clinical spinal research and its correlation with journal impact factor.

    Science.gov (United States)

    Amiri, Amir Reza; Kanesalingam, Kavitha; Cro, Suzie; Casey, Adrian T H

    2013-09-01

    Over the past two decades, there has been a growing recognition and emphasis on the practice of evidence-based medicine (EBM). The level of evidence (LOE) is used to classify clinical studies based on their quality and design. To compare the quality of scientific journals, the impact factor (IF) is the most widely used ranking measure. However, the calculation of IF is not directly dependent on the quality or LOE of clinical articles published in a journal. The primary aim of this study was to evaluate the current LOE for clinical research in leading spinal journals and assess the relationship between LOE and IF. We hypothesized that most clinical research would provide level IV evidence, and that a positive correlation would exist between the proportion of high LOE articles and the journal IF. A systematic review of all the articles in five general spinal journals was undertaken during 2010. All online articles in The Spine Journal, Spine, European Spine Journal, Journal of Neurosurgery: Spine, and Journal of Spinal Disorders and Techniques during 2010, as well as supplements were included. The LOE for each clinical study was assessed using guidelines produced by the Oxford Centre for Evidence-Based Medicine. Two reviewers independently assessed all articles. Overall 703 articles were suitable for LOE grading. Of these, 4.7% provided level I evidence, 23.2% level II, 12.5% level III, and 59.6% level IV. There was a significant association between LOE and type of study (pevidence. There was a strong positive correlation between the proportion of level I and II evidence and the journal impact factor (ρ=0.9; 95% confidence interval 0.1 to 0.99; p=.037). Spinal surgery journals with a higher IF contain a larger proportion of studies with high LOE, however most clinical articles provide level IV evidence of which the highest proportion are therapeutic studies. Clinicians, researchers, and journal editors should work hand in hand to enhance evidence-based practice in

  10. Wear mechanisms and friction parameters for sliding wear of micron-scale polysilicon sidewalls

    NARCIS (Netherlands)

    Alsem, D. H.; van der Hulst, R.; Stach, E. A.; Dugger, M. T.; De Hosson, J. Th. M.; Ritchie, R. O.

    As tribological properties are critical factors in the reliability of silicon-based microelectromechanical systems, it is important to understand what governs wear and friction. Average dynamic friction, wear volumes and morphology have been studied for polysilicon devices fabricated using the

  11. The moderating effects of sample type as evidence of the effects of faking on personality scale correlations and factor structure

    Directory of Open Access Journals (Sweden)

    KEVIN M. BRADLEY

    2006-09-01

    Full Text Available Motivational differences as a function of sample type (applicants versus incumbents have frequently been suspected of causing meaningful differences in the psychometric properties of personality inventories due to the effects of faking. In this quantitative review, correlations among the Big Five personality constructs were estimated and sample type was examined as a potential moderator of the personality construct inter-correlations. The resulting subgroup meta-analytic correlation matrices were factor-analyzed, and the second order factor solutions for job incumbents and job applicants were compared. Results of the meta-analyses indicate frequent, but small moderating effects. The second order factor analyses indicated that the observed moderation had little effect on the congruence of factor loadings. Together, the results are consistent with the position that faking is of little practical consequence in selection settings.

  12. Spatial and Temporal Patterns of Global NDVI Trends: Correlations with Climate and Human Factors

    Directory of Open Access Journals (Sweden)

    Ya Liu

    2015-10-01

    Full Text Available Changes in vegetation activity are driven by multiple natural and anthropogenic factors, which can be reflected by Normalized Difference Vegetation Index (NDVI derived from satellites. In this paper, NDVI trends from 1982 to 2012 are first estimated by the Theil–Sen median slope method to explore their spatial and temporal patterns. Then, the impact of climate variables and human activity on the observed NDVI trends is analyzed. Our results show that on average, NDVI increased by 0.46 × 10−3 per year from 1982 to 2012 globally with decadal variations. For most regions of the world, a greening (increasing–browning (decreasing–greening (G-B-G trend is observed over the periods 1982–2004, 1995–2004, and 2005–2012, respectively. A positive partial correlation of NDVI and temperature is observed in the first period but it decreases and occasionally becomes negative in the following periods, especially in the Humid Temperate and Dry Domain Regions. This suggests a weakened effect of temperature on vegetation growth. Precipitation, on the other hand, is found to have a positive impact on the NDVI trend. This effect becomes stronger in the third period of 1995–2004, especially in the Dry Domain Region. Anthropogenic effects and human activities, derived here from the Human Footprint Dataset and the associated Human Influence Index (HII, have varied impacts on the magnitude (absolute value of the NDVI trends across continents. Significant positive effects are found in Asia, Africa, and Europe, suggesting that intensive human activity could accelerate the change in NDVI and vegetation. A more accurate attribution of vegetation change to specific climatic and anthropogenic factors is instrumental to understand vegetation dynamics and requires further research.

  13. The Reality of Casimir Friction

    Directory of Open Access Journals (Sweden)

    Kimball A. Milton

    2016-04-01

    Full Text Available For more than 35 years theorists have studied quantum or Casimir friction, which occurs when two smooth bodies move transversely to each other, experiencing a frictional dissipative force due to quantum electromagnetic fluctuations, which break time-reversal symmetry. These forces are typically very small, unless the bodies are nearly touching, and consequently such effects have never been observed, although lateral Casimir forces have been seen for corrugated surfaces. Partly because of the lack of contact with observations, theoretical predictions for the frictional force between parallel plates, or between a polarizable atom and a metallic plate, have varied widely. Here, we review the history of these calculations, show that theoretical consensus is emerging, and offer some hope that it might be possible to experimentally confirm this phenomenon of dissipative quantum electrodynamics.

  14. Skin friction blistering: computer model.

    Science.gov (United States)

    Xing, Malcolm; Pan, Ning; Zhong, Wen; Maibach, Howard

    2007-08-01

    Friction blisters, a common injury in sports and military operations, can adversely effect or even halt performance. Given its frequency and hazardous nature, recent research efforts appear limited. Blistering can be treated as a delamination phenomenon; similar issues in materials science have been extensively investigated in theory and experiment. An obstacle in studying blistering is the difficulty of conducting experiment on humans and animals. Computer modeling thus becomes a preferred tool. This paper used a dynamic non-linear finite-element model with a blister-characterized structure and contact algorithm for outer materials and blister roof to investigate the effects on deformation and stress of an existing blister by changing the friction coefficient and elastic modulus of the material in contact with the blister. Through the dynamics mode and harmonic frequency approach, we demonstrated that the loading frequency leads to dramatic changes of displacement and stress in spite of otherwise similar loading. Our simulations show that an increased friction coefficient does not necessarily result in an increase in either the stress on the hot spot or blister deformation; local maximum friction stress and Von Mises stress exist for some friction coefficients over the wide range examined here. In addition, the stiffness of contact material on blistering is also investigated, and no significant effects on deformation and Von Mises stress are found, again at the range used. The model and method provided here may be useful for evaluating loading environments and contact materials in reducing blistering incidents. The coupling finite-element model can predict the effects of friction coefficient and contacting materials&apos stiffness on blister deformation and hot spot stress.

  15. Environmental Factors Correlated with the Metabolite Profile of Vitis vinifera cv. Pinot Noir Berry Skins along a European Latitudinal Gradient.

    Science.gov (United States)

    Del-Castillo-Alonso, María Ángeles; Castagna, Antonella; Csepregi, Kristóf; Hideg, Éva; Jakab, Gabor; Jansen, Marcel A K; Jug, Tjaša; Llorens, Laura; Mátai, Anikó; Martínez-Lüscher, Johann; Monforte, Laura; Neugart, Susanne; Olejnickova, Julie; Ranieri, Annamaria; Schödl-Hummel, Katharina; Schreiner, Monika; Soriano, Gonzalo; Teszlák, Péter; Tittmann, Susanne; Urban, Otmar; Verdaguer, Dolors; Zipoli, Gaetano; Martínez-Abaigar, Javier; Núñez-Olivera, Encarnación

    2016-11-23

    Mature berries of Pinot Noir grapevines were sampled across a latitudinal gradient in Europe, from southern Spain to central Germany. Our aim was to study the influence of latitude-dependent environmental factors on the metabolite composition (mainly phenolic compounds) of berry skins. Solar radiation variables were positively correlated with flavonols and flavanonols and, to a lesser extent, with stilbenes and cinnamic acids. The daily means of global and erythematic UV solar radiation over long periods (bud break-veraison, bud break-harvest, and veraison-harvest), and the doses and daily means in shorter development periods (5-10 days before veraison and harvest) were the variables best correlated with the phenolic profile. The ratio between trihydroxylated and monohydroxylated flavonols, which was positively correlated with antioxidant capacity, was the berry skin variable best correlated with those radiation variables. Total flavanols and total anthocyanins did not show any correlation with radiation variables. Air temperature, degree days, rainfall, and aridity indices showed fewer correlations with metabolite contents than radiation. Moreover, the latter correlations were restricted to the period veraison-harvest, where radiation, temperature, and water availability variables were correlated, making it difficult to separate the possible individual effects of each type of variable. The data show that managing environmental factors, in particular global and UV radiation, through cultural practices during specific development periods, can be useful to promote the synthesis of valuable nutraceuticals and metabolites that influence wine quality.

  16. Machine Learning of Fault Friction

    Science.gov (United States)

    Johnson, P. A.; Rouet-Leduc, B.; Hulbert, C.; Marone, C.; Guyer, R. A.

    2017-12-01

    We are applying machine learning (ML) techniques to continuous acoustic emission (AE) data from laboratory earthquake experiments. Our goal is to apply explicit ML methods to this acoustic datathe AE in order to infer frictional properties of a laboratory fault. The experiment is a double direct shear apparatus comprised of fault blocks surrounding fault gouge comprised of glass beads or quartz powder. Fault characteristics are recorded, including shear stress, applied load (bulk friction = shear stress/normal load) and shear velocity. The raw acoustic signal is continuously recorded. We rely on explicit decision tree approaches (Random Forest and Gradient Boosted Trees) that allow us to identify important features linked to the fault friction. A training procedure that employs both the AE and the recorded shear stress from the experiment is first conducted. Then, testing takes place on data the algorithm has never seen before, using only the continuous AE signal. We find that these methods provide rich information regarding frictional processes during slip (Rouet-Leduc et al., 2017a; Hulbert et al., 2017). In addition, similar machine learning approaches predict failure times, as well as slip magnitudes in some cases. We find that these methods work for both stick slip and slow slip experiments, for periodic slip and for aperiodic slip. We also derive a fundamental relationship between the AE and the friction describing the frictional behavior of any earthquake slip cycle in a given experiment (Rouet-Leduc et al., 2017b). Our goal is to ultimately scale these approaches to Earth geophysical data to probe fault friction. References Rouet-Leduc, B., C. Hulbert, N. Lubbers, K. Barros, C. Humphreys and P. A. Johnson, Machine learning predicts laboratory earthquakes, in review (2017). https://arxiv.org/abs/1702.05774Rouet-LeDuc, B. et al., Friction Laws Derived From the Acoustic Emissions of a Laboratory Fault by Machine Learning (2017), AGU Fall Meeting Session S025

  17. Reconsideration of data and correlations for plate finned-tube heat exchangers

    Science.gov (United States)

    Otović, Milena; Mihailović, Miloš; Genić, Srbislav; Jaćimović, Branislav; Milovančević, Uroš; Marković, Saša

    2018-04-01

    This paper deals with heat exchangers having plain finned tubes in staggered (triangular) pattern. The objective of this paper is to provide the heat transfer and friction factor correlation which can be used in engineering practice. For this purpose, the experimental data of several (most cited) authors who deal with this type of heat exchangers are used. The new correlations are established to predict the air-side heat transfer coefficient and friction factor as a function of the Reynolds number and geometric variables of the heat exchanger - tube diameter, tube pitch, fin spacing, tube rows, etc. In those correlations the characteristic dimension in Reynolds number is calculated by using the new parameter - volumetric porosity. Also, there are given the errors of those correlations.

  18. Estimating productivity costs using the friction cost approach in practice: a systematic review.

    Science.gov (United States)

    Kigozi, Jesse; Jowett, Sue; Lewis, Martyn; Barton, Pelham; Coast, Joanna

    2016-01-01

    The choice of the most appropriate approach to valuing productivity loss has received much debate in the literature. The friction cost approach has been proposed as a more appropriate alternative to the human capital approach when valuing productivity loss, although its application remains limited. This study reviews application of the friction cost approach in health economic studies and examines how its use varies in practice across different country settings. A systematic review was performed to identify economic evaluation studies that have estimated productivity costs using the friction cost approach and published in English from 1996 to 2013. A standard template was developed and used to extract information from studies meeting the inclusion criteria. The search yielded 46 studies from 12 countries. Of these, 28 were from the Netherlands. Thirty-five studies reported the length of friction period used, with only 16 stating explicitly the source of the friction period. Nine studies reported the elasticity correction factor used. The reported friction cost approach methods used to derive productivity costs varied in quality across studies from different countries. Few health economic studies have estimated productivity costs using the friction cost approach. The estimation and reporting of productivity costs using this method appears to differ in quality by country. The review reveals gaps and lack of clarity in reporting of methods for friction cost evaluation. Generating reporting guidelines and country-specific parameters for the friction cost approach is recommended if increased application and accuracy of the method is to be realized.

  19. Literature survey on microscopic friction modeling

    NARCIS (Netherlands)

    Hol, J.

    2010-01-01

    To better understand contact and friction conditions, experimental and theoretical studies have been performed in order to take microscopic dependencies into account. Friction is developed on microscopic level by adhesion between contacting asperities, the ploughing effect between asperities and the

  20. Experimental determination and evaluation of the friction behavior of geosynthetics; Experimentelle Ermittlung und Bewertung des Reibungsverhaltens von Geokunststoffen

    Energy Technology Data Exchange (ETDEWEB)

    Heinemann, Maik

    2016-08-17

    ranges as weil as various non-linear approaches for the analytical modeling of the relationship between normal stress and friction stress. Tests carried out with specimens, which are first loaded with the effective forces as they occur inside an embankment for a long period, before being loaded to the ultimate limit state, show that the friction resistance increases with the passing of time. This correlation is due to increase of material contact associated with the creep deformation and due to general stress redistribution. Based on friction tests with elevated temperatures in relation to standard test conditions, a significant decrease in friction resistance is detected with increasing temperature, which is due to the change in the mechanical properties of thermoplastics PE and PP. Based on the results of extensive experimental and analytical investigations concrete amendments and supplements to the GDA E 3-8 and a reduction of the factor for determining the characteristic value of adhesion from 2.0 (or 1.5) in accordance to GDA E 2-7 to 1.3 is recommended.

  1. Methods and Devices used to Measure Friction

    DEFF Research Database (Denmark)

    Jeswiet, Jack; Arentoft, Mogens; Henningsen, Poul

    2004-01-01

    . To gain a good understanding of the mechanisms at the interface and to be able to verify the friction and tribology models that exist, friction sensors are needed. Designing sensors to measure friction-stress in metal working has been pursued by many researchers. This paper surveys methods, which have...... been tried in the past and discusses some of the recent sensor designs, which can now be used to measure Friction in both production situations and for research purposes....

  2. Apparatus for measurement of coefficient of friction

    Science.gov (United States)

    Slifka, A. J.; Siegwarth, J. D.; Sparks, L. L.; Chaudhuri, Dilip K.

    1990-01-01

    An apparatus designed to measure the coefficient of friction in certain controlled atmospheres is described. The coefficient of friction observed during high-load tests was nearly constant, with an average value of 0.56. This value is in general agreement with that found in the literature and also with the initial friction coefficient value of 0.67 measured during self-mated friction of 440C steel in an oxygen environment.

  3. A field theoretic model for static friction

    OpenAIRE

    Mahyaeh, I.; Rouhani, S.

    2013-01-01

    We present a field theoretic model for friction, where the friction coefficient between two surfaces may be calculated based on elastic properties of the surfaces. We assume that the geometry of contact surface is not unusual. We verify Amonton's laws to hold that friction force is proportional to the normal load.This model gives the opportunity to calculate the static coefficient of friction for a few cases, and show that it is in agreement with observed values. Furthermore we show that the ...

  4. Exploring the role of internal friction in the dynamics of unfolded proteins using simple polymer models

    Science.gov (United States)

    Cheng, Ryan R.; Hawk, Alexander T.; Makarov, Dmitrii E.

    2013-02-01

    Recent experiments showed that the reconfiguration dynamics of unfolded proteins are often adequately described by simple polymer models. In particular, the Rouse model with internal friction (RIF) captures internal friction effects as observed in single-molecule fluorescence correlation spectroscopy (FCS) studies of a number of proteins. Here we use RIF, and its non-free draining analog, Zimm model with internal friction, to explore the effect of internal friction on the rate with which intramolecular contacts can be formed within the unfolded chain. Unlike the reconfiguration times inferred from FCS experiments, which depend linearly on the solvent viscosity, the first passage times to form intramolecular contacts are shown to display a more complex viscosity dependence. We further describe scaling relationships obeyed by contact formation times in the limits of high and low internal friction. Our findings provide experimentally testable predictions that can serve as a framework for the analysis of future studies of contact formation in proteins.

  5. Sustained frictional instabilities on nanodomed surfaces: Stick-slip amplitude coefficient

    DEFF Research Database (Denmark)

    Quignon, Benoit; Pilkington, Georgia A.; Thormann, Esben

    2013-01-01

    properties and their measured friction coefficients was identified. Furthermore, all the nanodomed textures exhibited pronounced oscillations in the shear traces, similar to the classic stick-slip behavior, under all the shear velocities and load regimes studied. That is, the nanotextured topography led...... to sustained frictional instabilities, effectively with no contact frictional sliding. The amplitude of the stick-slip oscillations, σf, was found to correlate with the topographic properties of the surfaces and scale linearly with the applied load. In line with the friction coefficient, we define the slope...... of this linear plot as the stick-slip amplitude coefficient (SSAC). We suggest that such stick-slip behaviors are characteristics of surfaces with nanotextures and that such local frictional instabilities have important implications to surface damage and wear. We thus propose that the shear characteristics...

  6. Upset Prediction in Friction Welding Using Radial Basis Function Neural Network

    Directory of Open Access Journals (Sweden)

    Wei Liu

    2013-01-01

    Full Text Available This paper addresses the upset prediction problem of friction welded joints. Based on finite element simulations of inertia friction welding (IFW, a radial basis function (RBF neural network was developed initially to predict the final upset for a number of welding parameters. The predicted joint upset by the RBF neural network was compared to validated finite element simulations, producing an error of less than 8.16% which is reasonable. Furthermore, the effects of initial rotational speed and axial pressure on the upset were investigated in relation to energy conversion with the RBF neural network. The developed RBF neural network was also applied to linear friction welding (LFW and continuous drive friction welding (CDFW. The correlation coefficients of RBF prediction for LFW and CDFW were 0.963 and 0.998, respectively, which further suggest that an RBF neural network is an effective method for upset prediction of friction welded joints.

  7. Finite Element Analysis of the Amontons-Coulomb's Model using Local and Global Friction Tests

    International Nuclear Information System (INIS)

    Oliveira, M. C.; Menezes, L. F.; Ramalho, A.; Alves, J. L.

    2011-01-01

    In spite of the abundant number of experimental friction tests that have been reported, the contact with friction modeling persists to be one of the factors that determine the effectiveness of sheet metal forming simulation. This difficulty can be understood due to the nature of the friction phenomena, which comprises the interaction of different factors connected to both sheet and tools' surfaces. Although in finite element numerical simulations friction models are commonly applied at the local level, they normally rely on parameters identified based on global experimental tests results. The aim of this study is to analyze the applicability of the Amontons-Coulomb's friction coefficient identified using complementary tests: (i) load-scanning, at the local level and (ii) draw-bead, at the global level; to the numerical simulation of sheet metal forming processes.

  8. FEM simulation of friction testing method based on combined forward rod-backward can extrusion

    DEFF Research Database (Denmark)

    Nakamura, T; Bay, Niels; Zhang, Z. L

    1997-01-01

    A new friction testing method by combined forward rod-backward can extrusion is proposed in order to evaluate frictional characteristics of lubricants in forging processes. By this method the friction coefficient mu and the friction factor m can be estimated along the container wall and the conical...... die surface in the forward rod extrusion using theoretical calibration diagrams representing the relationship between the punch travel, the forward rod extrusion length and mu or m without requirements of measuring the forming forces and the paw stress of the workpiece. The theoretical calibration...... curves are obtained by rigid-plastic FEM simulations in a combined forward rod-backward can extrusion process for a reduction in area R-b = 25, 50 and 70 percent in the backward can extrusion. It is confirmed that the friction factor m(p) on the punch nose in the backward cart extrusion has almost...

  9. Studies on the frictional behavior of magnetic recording tapes

    Science.gov (United States)

    Kalfayan, S. H.; Silver, R. H.; Hoffman, J. K.

    1972-01-01

    Methods were developed for measuring frictional forces acting on a magnetic tape in motion or at rest, as well as the extent of stick slip. The effects of factors such as temperature, humidity, kind of gaseous atmosphere, and tape speed on the frictional interaction between various tapes and heads were investigated. Results were instrumental in the selection of a tape for the Mariner Mars 1971 spacecraft. Studies are reported on the stick slip behavior of tapes and the performance of a metallic tape, compared with the usual plastic tapes.

  10. Friction of Droplets Sliding on Microstructured Superhydrophobic Surfaces.

    Science.gov (United States)

    Qiao, Shasha; Li, Shen; Li, Qunyang; Li, Bo; Liu, Kesong; Feng, Xi-Qiao

    2017-11-28

    Liquid transport is a fundamental process relevant to a wide range of applications, for example, heat transfer, anti-icing, self-cleaning, drag reduction, and microfluidic systems. For these applications, a deeper understanding of the sliding behavior of water droplets on solid surfaces is of particular importance. In this study, the frictional behavior of water droplets sliding on superhydrophobic surfaces decorated with micropillar arrays was studied using a nanotribometer. Our experiments show that surfaces with a higher solid area fraction generally exhibited larger friction, although friction might drop when the solid area fraction was close to unity. More interestingly, we found that the sliding friction of droplets was enhanced when the dimension of the microstructures increased, showing a distinct size effect. The nonmonotonic dependence of friction force on solid area fraction and the apparent size effect can be qualitatively explained by the evolution of two governing factors, that is, the true length of the contact line and the coordination degree of the depinning events. The mechanisms are expected to be generally applicable for other liquid transport processes involving the dynamic motion of a three-phase contact line, which may provide a new means of tuning liquid-transfer behavior through surface microstructures.

  11. Correlation models between environmental factors and bacterial resistance to antimony and copper.

    Directory of Open Access Journals (Sweden)

    Zunji Shi

    Full Text Available Antimony (Sb and copper (Cu are toxic heavy metals that are associated with a wide variety of minerals. Sb(III-oxidizing bacteria that convert the toxic Sb(III to the less toxic Sb(V are potentially useful for environmental Sb bioremediation. A total of 125 culturable Sb(III/Cu(II-resistant bacteria from 11 different types of mining soils were isolated. Four strains identified as Arthrobacter, Acinetobacter and Janibacter exhibited notably high minimum inhibitory concentrations (MICs for Sb(III (>10 mM,making them the most highly Sb(III-resistant bacteria to date. Thirty-six strains were able to oxidize Sb(III, including Pseudomonas-, Comamonas-, Acinetobacter-, Sphingopyxis-, Paracoccus- Aminobacter-, Arthrobacter-, Bacillus-, Janibacter- and Variovorax-like isolates. Canonical correspondence analysis (CCA revealed that the soil concentrations of Sb and Cu were the most obvious environmental factors affecting the culturable bacterial population structures. Stepwise linear regression was used to create two predictive models for the correlation between soil characteristics and the bacterial Sb(III or Cu(II resistance. The concentrations of Sb and Cu in the soil was the significant factors affecting the bacterial Sb(III resistance, whereas the concentrations of S and P in the soil greatly affected the bacterial Cu(II resistance. The two stepwise linear regression models that we derived are as follows: MIC(Sb(III=606.605+0.14533 x C(Sb+0.4128 x C(Cu and MIC((Cu(II=58.3844+0.02119 x C(S+0.00199 x CP [where the MIC(Sb(III and MIC(Cu(II represent the average bacterial MIC for the metal of each soil (μM, and the C(Sb, C(Cu, C(S and C(P represent concentrations for Sb, Cu, S and P (mg/kg in soil, respectively, p<0.01]. The stepwise linear regression models we developed suggest that metals as well as other soil physicochemical parameters can contribute to bacterial resistance to metals.

  12. Correlation of serum cytokines, chemokines, growth factors and enzymes with periodontal disease parameters.

    Science.gov (United States)

    Panezai, Jeneen; Ghaffar, Ambereen; Altamash, Mohammad; Sundqvist, Karl-Gösta; Engström, Per-Erik; Larsson, Anders

    2017-01-01

    Periodontal disease (PD) is characterized by inflammatory tissue destruction in tooth supporting apparatus. Many studies indicate that the underlying pathogenesis is in concordance with rheumatoid arthritis (RA) sharing immune-inflammatory events affect both diseases. The aim of this study was to investigate serum cytokines, chemokines, growth factors, enzymes and costimulatory proteins in association with periodontal conditions in PD and RA subjects. Periodontal examination was performed in RA (n = 38), PD (n = 38) and healthy subjects (n = 14). Bleeding on probing (BOP) and probing pocket depth (PPD) were measured. Marginal bone loss (MBL) for premolars and molars was measured on digital panoramic radiographs. PD was defined as present if the PPD was ≥5mm in ≥ 3 different sites. Serum samples were collected from all subjects. A multiplex proximity extension assay (PEA) was used to analyze the samples for simultaneous measurement of 92 cytokines. Cytokines with ≥ 60% quantitative results were included. A significant positive correlation was seen for ST1A1, FGF-19 and NT-3 whereas EN-RAGE, DNER, CX3CL1 and TWEAK associated inversely with BOP, PPD≥ 5mm and MBL but positively with number of teeth. Several CD markers (CD244, CD40, CDCP1, LIF-R, IL-10RA, CD5 and CD6) were found to be associated with BOP, shallow and deep pockets, MBL and number of teeth, either directly or inversely. Most chemokines (CCL8, CX3CL1, CXCL10, CXCL11, CCL11, CCL4, CCL20, CXCL5, CXCL6, and CCL23) were positively associated with number of teeth and some inversely related to MBL (CCL8, CXCL10). Proteins with enzymatic activity (ST1A1, HGF and CASP-8) were directly related to the severity of periodontal conditions and inversely related to number of teeth. Aside from FGF-19, other growth factors were also directly associated with MBL (HGF), number of teeth (VEGF-A, LAP TGF-beta-1) and, inversely to, shallow pockets (LAP TGF-beta-1, TGFA and Beta-NGF). Out of 33 cytokines, 32 associated

  13. Correlation between genetic variability and virulence factors in clinical strains of Malassezia pachydermatis of animal origin.

    Science.gov (United States)

    Buommino, Elisabetta; Nocera, Francesca Paola; Parisi, Annamaria; Rizzo, Antonietta; Donnarumma, Giovanna; Mallardo, Karina; Fiorito, Filomena; Baroni, Adone; De Martino, Luisa

    2016-07-01

    Malassezia pachydermatis is a yeast belonging to the microbiota of the skin and mucous membranes of dog and cat, but it can also act as pathogen, causing dermatitis. The aim of this work was to evaluate the genetic variability of M. pachydermatis strains isolated from symptomatic dogs and cats and determine a correlation between genotype and phenotype. For this purpose eleven strains of M. pachydermatis were molecularly classified by nested-polymerase chain reaction (nested-PCR) based on ITS-1 and ITS-2 regions, specific for fungal rRNA genes. Furthermore, random amplification of polymorphic DNA (RAPD) was applied for genetic typing of M. pachydermatis isolates identifying four different genotypes. Strains belonging to genotype 1 produced the highest amount of biofilm and phospholipase activity. The inflammatory response induced by M. pachydermatis strains in immortalized human keratinocytes (HaCat cells) was significantly different when we compared the results obtained from each strain. In particular, HaCat cells infected with the strains belonging to genotypes 1 and 2 triggered the highest levels of increase in TLR-2, IL-1β, IL-6, IL-8, COX-2 and MMP-9 expression. By contrast, cells infected with the strains of genotype 3 and those of genotype 4 did not significantly induce TLR-2 and cytokines. The results obtained might suggest a possible association between genotype and virulence factors expressed by M. pachydermatis strains. This highlights the need for a more accurate identification of the yeast to improve the therapeutic approach and to monitor the onset of human infections caused by this emergent zoonotic pathogen.

  14. Correlation of Clinical and Dosimetric Factors With Adverse Pulmonary Outcomes in Children After Lung Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Venkatramani, Rajkumar, E-mail: rvenkatramani@chla.usc.edu [Division of Hematology/Oncology, Children' s Hospital Los Angeles, Los Angeles, California (United States); Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California (United States); Kamath, Sunil [Department of Pulmonology, Children' s Hospital Los Angeles, Los Angeles, California (United States); Wong, Kenneth [Division of Hematology/Oncology, Children' s Hospital Los Angeles, Los Angeles, California (United States); Olch, Arthur J. [Division of Hematology/Oncology, Children' s Hospital Los Angeles, Los Angeles, California (United States); Department of Radiation Oncology, University of Southern California, Los Angeles, California (United States); Malvar, Jemily [Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California (United States); Sposto, Richard [Division of Hematology/Oncology, Children' s Hospital Los Angeles, Los Angeles, California (United States); Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California (United States); Goodarzian, Fariba [Department of Radiology, Children' s Hospital Los Angeles, Los Angeles, California (United States); Freyer, David R. [Division of Hematology/Oncology, Children' s Hospital Los Angeles, Los Angeles, California (United States); Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California (United States); Keens, Thomas G. [Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, California (United States); Department of Pulmonology, Children' s Hospital Los Angeles, Los Angeles, California (United States); and others

    2013-08-01

    Purpose: To identify the incidence and the risk factors for pulmonary toxicity in children treated for cancer with contemporary lung irradiation. Methods and Materials: We analyzed clinical features, radiographic findings, pulmonary function tests, and dosimetric parameters of children receiving irradiation to the lung fields over a 10-year period. Results: We identified 109 patients (75 male patients). The median age at irradiation was 13.8 years (range, 0.04-20.9 years). The median follow-up period was 3.4 years. The median prescribed radiation dose was 21 Gy (range, 0.4-64.8 Gy). Pulmonary toxic chemotherapy included bleomycin in 58.7% of patients and cyclophosphamide in 83.5%. The following pulmonary outcomes were identified and the 5-year cumulative incidence after irradiation was determined: pneumonitis, 6%; chronic cough, 10%; pneumonia, 35%; dyspnea, 11%; supplemental oxygen requirement, 2%; radiographic interstitial lung disease, 40%; and chest wall deformity, 12%. One patient died of progressive respiratory failure. Post-irradiation pulmonary function tests available from 44 patients showed evidence of obstructive lung disease (25%), restrictive disease (11%), hyperinflation (32%), and abnormal diffusion capacity (12%). Thoracic surgery, bleomycin, age, mean lung irradiation dose (MLD), maximum lung dose, prescribed dose, and dosimetric parameters between V{sub 22} (volume of lung exposed to a radiation dose ≥22 Gy) and V{sub 30} (volume of lung exposed to a radiation dose ≥30 Gy) were significant for the development of adverse pulmonary outcomes on univariate analysis. MLD, maximum lung dose, and V{sub dose} (percentage of volume of lung receiving the threshold dose or greater) were highly correlated. On multivariate analysis, MLD was the sole significant predictor of adverse pulmonary outcome (P=.01). Conclusions: Significant pulmonary dysfunction occurs in children receiving lung irradiation by contemporary techniques. MLD rather than prescribed

  15. [Correlation between epigenetic alterations in the insulin growth factor-II gene and hepatocellular carcinoma].

    Science.gov (United States)

    Dong, Zhi-zhen; Yao, Deng-fu; Wu, Wei; Qiu, Li-wei; Yao, Ning-hua; Yan, Xiao-di; Yu, Dan-dan; Chen, Jie

    2012-08-01

    To investigate whether epigenetic alterations in the insulin-like growth factor-II (IGF-II) gene that cause differential transcription or expression are correlated with onset and severity of hepatocellular carcinoma (HCC). Patient-matched specimens of HCC, paracancerous, and non-cancerous tissues were collected from 40 primary liver cancer patients. Epigenetic alterations in the promoter (P3) sequence of the IGF-II gene were analyzed by methylation-specific PCR (MSP) and IGF-II transcription was measured by RT-PCR. IGF-II protein expression and clinicopathological features were assessed by immunohistochemistry and microscopic observation. The rate of IGF-II P3 methylation was significantly lower in HCC tissues (0%) than in paracancerous tissues (vs. 47.5%; x2 = 24.918, P less than 0.001) and non-cancerous tissues (vs. 100%; x2 = 80.000, P less than 0.001). IGF-II mRNA expression was significantly higher in HCC tissues (100%) than in paracancerous tissues (vs. 52.5%; x2 = 24.918, P less than 0.001) and non-cancerous tissues (vs. 0%; x2 = 80.000, P less than 0.001). IGF-II protein expression was significantly higher in HCC tissues (82.5%) than in paracancerous tissues (vs. 45.0%; x2 = 12.170, P less than 0.001) and non-cancerous tissues (vs. 0%; x2 = 56.170, P less than 0.001). IGF-II overexpression in HCC was significantly associated with degree of differentiation, extent of infiltrated serosa, size of tumor, and HBV-positive infection status. Epigenetic alterations in the IGF-II gene regulate its transcription and expression and are closely associated with HCC development and progression.

  16. Microwave Imaging Sensor Using Compact Metamaterial UWB Antenna with a High Correlation Factor

    Directory of Open Access Journals (Sweden)

    Md. Moinul Islam

    2015-07-01

    Full Text Available The design of a compact metamaterial ultra-wideband (UWB antenna with a goal towards application in microwave imaging systems for detecting unwanted cells in human tissue, such as in cases of breast cancer, heart failure and brain stroke detection is proposed. This proposed UWB antenna is made of four metamaterial unit cells, where each cell is an integration of a modified split ring resonator (SRR, capacitive loaded strip (CLS and wire, to attain a design layout that simultaneously exhibits both a negative magnetic permeability and a negative electrical permittivity. This design results in an astonishing negative refractive index that enables amplification of the radiated power of this reported antenna, and therefore, high antenna performance. A low-cost FR4 substrate material is used to design and print this reported antenna, and has the following characteristics: thickness of 1.6 mm, relative permeability of one, relative permittivity of 4.60 and loss tangent of 0.02. The overall antenna size is 19.36 mm × 27.72 mm × 1.6 mm where the electrical dimension is 0.20 λ × 0.28 λ × 0.016 λ at the 3.05 GHz lower frequency band. Voltage Standing Wave Ratio (VSWR measurements have illustrated that this antenna exhibits an impedance bandwidth from 3.05 GHz to more than 15 GHz for VSWR < 2 with an average gain of 4.38 dBi throughout the operating frequency band. The simulations (both HFSS and computer simulation technology (CST and the measurements are in high agreement. A high correlation factor and the capability of detecting tumour simulants confirm that this reported UWB antenna can be used as an imaging sensor.

  17. Correlation of human epidermal growth factor receptor protein expression and colorectal cancer.

    Science.gov (United States)

    Yang, Wen-Juan; Shen, Xing-Jie; Ma, Xiao-Xia; Tan, Zhi-Gang; Song, Yan; Guo, Yi-Tong; Yuan, Mei

    2015-07-28

    To investigate the correlation between human epidermal growth factor receptor (HER-2) protein expression and colorectal cancer (CRC) using a case-control study and meta-analysis. Tumor tissue specimens from 162 CRC patients were selected for the case group. Fifty cases were randomly selected, and normal CRC tissue at least 10 cm away from the tumor margins of these cases was used to generate the control group. The expression of the HER-2 protein in the 162 CRC tissue samples and the 50 adjacent normal mucosa tissue samples was detected via immunohistochemistry. The experimental data were analyzed using SPSS 18.0 software, and R software version 3.1.0 was utilized for further verification. The expression of HER-2 protein in the 162 CRC tissue samples was significantly higher than in the normal tissue specimens. The data showed that the expression of HER-2 in CRC was related to the Dukes' stage, the depth of invasion and lymph node metastasis. The HER-2-positive patients had lower 3- and 5-year OS rates than the HER-2-negative patients, but there was no significant difference. However, there was a statistically significant difference in the 3- and 5-year disease-free survival (DFS) rates of HER-2-positive and HER-2-negative patients. The results of the meta-analysis showed that the expression of HER-2 in CRC patients was statistically significantly increased over that of healthy people. The 3-year DFS rate in HER-2-positive patients was markedly lower than that in HER-2-negative patients. Down-regulation of HER-2 expression might be a dependable strategy for CRC therapy.

  18. Lightweight concrete modification factor for shear friction.

    Science.gov (United States)

    2013-10-01

    This report describes the results of a study initiated to examine the influence of concrete unit weight on the direct shear transfer across an interface of concretes cast at different times. This type of interface is common with structural precast co...

  19. Asbestos free friction composition for brake linings

    Indian Academy of Sciences (India)

    An asbestos free friction material composite for brake linings is synthesized containing fibrous reinforcing constituents, friction imparting and controlling additives, elastomeric additives, fire retarding components and a thermosetting resin. The composite shows exemplary friction characteristics and has great resistance to ...

  20. Friction tensor concept for textured surfaces

    Indian Academy of Sciences (India)

    Depending on the sliding direction the coefficient of friction varies between maximum and minimum for textured surfaces. For random surfaces without any texture the friction coefficient becomes independent of the sliding direction. This paper proposes the concept of a friction tensor analogous to the heat conduction tensor ...

  1. 64Cu-DOTATATE for Noninvasive Assessment of Atherosclerosis in Large Arteries and Its Correlation with Risk Factors

    DEFF Research Database (Denmark)

    Malmberg, Catarina; Ripa, Rasmus Sejersten; Johnbeck, Camilla Bardram

    2015-01-01

    aimed to compare the uptake of the PET tracers (68)Ga-DOTATOC and (64)Cu-DOTATATE in large arteries, in the assessment of atherosclerosis by noninvasive imaging technique, combining PET and CT. Further, the correlation of uptake and cardiovascular risk factors was investigated. METHODS: Sixty...... was calculated. Uptake of the tracers was correlated with cardiovascular risk factors collected from medical records. RESULTS: We found detectable uptake of both tracers in all arterial segments studied. Uptake of (64)Cu-DOTATATE was significantly higher than (68)Ga-DOTATOC in the vascular regions both when...

  2. Information frictions and monetary policy

    Czech Academy of Sciences Publication Activity Database

    Matějka, Filip

    2012-01-01

    Roč. 6, č. 1 (2012), s. 7-24 ISSN 1802-792X Institutional support: RVO:67985998 Keywords : nominal rigidity * information frictions * monetary economics Subject RIV: AH - Economics http://www.vsfs.cz/periodika/acta-2012-01.pdf

  3. What do Information Frictions Do?

    NARCIS (Netherlands)

    Bhattacharya, J.; Chankraborty, S.

    2003-01-01

    Numerous researchers have incorporated labor or credit market frictions within simple neoclassical models to (i) facilitate quick departures from the Arrow-Debreu world, thereby opening up the role for institutions, (ii) inject some realism into their models, and (iii) explain cross country

  4. Frictional heating of tribological contacts

    NARCIS (Netherlands)

    Bos, Johannes

    1995-01-01

    Wherever friction occurs, mechanical energy is transformed into heat. The tem­ perature rise associated with this heating can have an important influence on the tribological behaviour of the contacting components. Apart from determining per­ formance, thermal phenomena affect reliability and may

  5. Preface: Friction at the nanoscale

    Science.gov (United States)

    Fusc, Claudio; Smith, Roger; Urbakh, Michael; Vanossi, Andrea

    2008-09-01

    Interfacial friction is one of the oldest problems in physics and chemistry, and certainly one of the most important from a practical point of view. Everyday operations on a broad range of scales, from nanometer and up, depend upon the smooth and satisfactory functioning of countless tribological systems. Friction imposes serious constraints and limitations on the performance and lifetime of micro-machines and, undoubtedly, will impose even more severe constraints on the emerging technology of nano-machines. Standard lubrication techniques used for large objects are expected to be less effective in the nano-world. Novel methods for control and manipulation are therefore needed. What has been missing is a molecular level understanding of processes occurring between and close to interacting surfaces to help understand, and later manipulate friction. Friction is intimately related to both adhesion and wear, and all three require an understanding of highly non-equilibrium processes occurring at the molecular level to determine what happens at the macroscopic level. Due to its practical importance and the relevance to basic scientific questions there has been major increase in activity in the study of interfacial friction on the microscopic level during the last decade. Intriguing structural and dynamical features have been observed experimentally. These observations have motivated theoretical efforts, both numerical and analytical. This special issue focusses primarily on discussion of microscopic mechanisms of friction and adhesion at the nanoscale level. The contributions cover many important aspects of frictional behaviour, including the origin of stick-slip motion, the dependence of measured forces on the material properties, effects of thermal fluctuations, surface roughness and instabilities in boundary lubricants on both static and kinetic friction. An important problem that has been raised in this issue, and which has still to be resolved, concerns the

  6. Personality disorders in substance abusers: Validation of the DIP-Q through principal components factor analysis and canonical correlation analysis

    Directory of Open Access Journals (Sweden)

    Hesse Morten

    2005-05-01

    Full Text Available Abstract Background Personality disorders are common in substance abusers. Self-report questionnaires that can aid in the assessment of personality disorders are commonly used in assessment, but are rarely validated. Methods The Danish DIP-Q as a measure of co-morbid personality disorders in substance abusers was validated through principal components factor analysis and canonical correlation analysis. A 4 components structure was constructed based on 238 protocols, representing antagonism, neuroticism, introversion and conscientiousness. The structure was compared with (a a 4-factor solution from the DIP-Q in a sample of Swedish drug and alcohol abusers (N = 133, and (b a consensus 4-components solution based on a meta-analysis of published correlation matrices of dimensional personality disorder scales. Results It was found that the 4-factor model of personality was congruent across the Danish and Swedish samples, and showed good congruence with the consensus model. A canonical correlation analysis was conducted on a subset of the Danish sample with staff ratings of pathology. Three factors that correlated highly between the two variable sets were found. These variables were highly similar to the three first factors from the principal components analysis, antagonism, neuroticism and introversion. Conclusion The findings support the validity of the DIP-Q as a measure of DSM-IV personality disorders in substance abusers.

  7. The effect of chalk on the finger-hold friction coefficient in rock climbing.

    Science.gov (United States)

    Amca, Arif Mithat; Vigouroux, Laurent; Aritan, Serdar; Berton, Eric

    2012-11-01

    The main purpose of this study was to examine the effect of chalk on the friction coefficient between climber's fingers and two different rock types (sandstone and limestone). The secondary purpose was to investigate the effects of humidity and temperature on the friction coefficient and on the influence of chalk. Eleven experienced climbers took part in this study and 42 test sessions were performed. Participants hung from holds which were fixed on a specially designed hang board. The inclination of the hang board was progressively increased until the climber's hand slipped from the holds. The angle of the hang board was simultaneously recorded by using a gyroscopic sensor and the friction coefficient was calculated at the moment of slip. The results showed that there was a significant positive effect of chalk on the coefficient of friction (+18.7% on limestone and +21.6% on sandstone). Moreover sandstone had a higher coefficient of friction than limestone (+15.6% without chalk, +18.4% with chalk). These results confirmed climbers' belief that chalk enhances friction. However, no correlation with humidity/temperature and friction coefficient was noted which suggested that additional parameters should be considered in order to understand the effects of climate on finger friction in rock climbing.

  8. Experimental and theoretical study of friction torque from radial ball bearings

    Science.gov (United States)

    Geonea, Ionut; Dumitru, Nicolae; Dumitru, Ilie

    2017-10-01

    In this paper it is presented a numerical simulation and an experimental study of total friction torque from radial ball bearings. For this purpose it is conceived a virtual CAD model of the experimental test bench for bearing friction torque measurement. The virtual model it is used for numerical simulation in Adams software, that allows dynamic study of multi-body systems and in particularly with facility Adams Machinery of dynamic behavior of machine parts. It is manufactured an experimental prototype of the test bench for radial ball bearings friction torque measurement. In order to measure the friction torque of the tested bearings it is used an equal resistance elastic beam element, with strain gauge transducer to measure bending deformations. The actuation electric motor of the bench has the shaft mounted on two bearings and the motor housing is fixed to the free side of the elastic beam, which is bended by a force proportional with the total friction torque. The beam elastic element with strain gauge transducer is calibrated in order to measure the force occurred. Experimental determination of the friction torque is made for several progressive radial loads. It is established the correlation from the friction torque and bearing radial load. The bench allows testing of several types and dimensions of radial bearings, in order to establish the bearing durability and of total friction torque.

  9. A multivariable model for predicting the frictional behaviour and hydration of the human skin.

    Science.gov (United States)

    Veijgen, N K; van der Heide, E; Masen, M A

    2013-08-01

    two coefficients of friction show a strong correlation. Consequently the two multivariable models resemble, with the static coefficient of friction being on average 18% lower than the dynamic coefficient of friction. The multivariable models in this study can be used to describe the data set that was the basis for this study. Care should be taken when generalising these results. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Correlations among socioeconomic and family factors and academic, behavioral, and emotional difficulties in Filipino adolescents in Hawai'i.

    Science.gov (United States)

    Guerrero, Anthony P S; Hishinuma, Earl S; Andrade, Naleen N; Nishimura, Stephanie T; Cunanan, Vanessa L

    2006-07-01

    Because of socioeconomic and acculturative challenges faced by immigrant families, Filipino adolescents in Hawai'i may be at risk for academic, behavioral and emotional difficulties. To determine, among Filipino adolescents in Hawai'i, whether measures of economic hardship and lower socioeconomic status (SES) correlate positively with poor school performance, aggressive behavior, substance use, anxiety, and depression; and whether family support and cultural identification correlate negatively with these difficulties. 216 Filipino adolescents from four public high schools in Hawai'i (1993-1994) were given surveys that assessed basic demographic information, measures of family support and other social variables, and measures of school performance, depression, anxiety, aggression and substance use. In the total sample, low SES seemed to correlate with poor school performance and behavioral and emotional difficulties. In both the total sample and the sub-sample of adolescents with lower SES, family support was a universally strong protective factor. Learning genealogy was positively correlated with school performance, and speaking a language other than English was inversely correlated with substance use (in the whole sample) and depression (in the lower SES sub-sample). For Filipino adolescents (in both the whole and lower-SES samples), family support was an important protective factor against academic, behavioral and emotional difficulties. The role of cultural identification as a risk or protective factor among Filipino adolescents deserves further investigation.

  11. Friction, Free Axes of Rotation and Entropy

    Directory of Open Access Journals (Sweden)

    Alexander Kazachkov

    2017-03-01

    Full Text Available Friction forces acting on rotators may promote their alignment and therefore eliminate degrees of freedom in their movement. The alignment of rotators by friction force was shown by experiments performed with different spinners, demonstrating how friction generates negentropy in a system of rotators. A gas of rigid rotators influenced by friction force is considered. The orientational negentropy generated by a friction force was estimated with the Sackur-Tetrode equation. The minimal change in total entropy of a system of rotators, corresponding to their eventual alignment, decreases with temperature. The reported effect may be of primary importance for the phase equilibrium and motion of ubiquitous colloidal and granular systems.

  12. [Correlation analysis on normalized difference vegetation index (NDVI) of different vegetations and climatic factors in Southwest China].

    Science.gov (United States)

    Zhang, Yuan-Dong; Zhang, Xiao-He; Liu, Shi-Rong

    2011-02-01

    Based on the 1982-2006 NDVI remote sensing data and meteorological data of Southwest China, and by using GIS technology, this paper interpolated and extracted the mean annual temperature, annual precipitation, and drought index in the region, and analyzed the correlations of the annual variation of NDVI in different vegetation types (marsh, shrub, bush, grassland, meadow, coniferous forest, broad-leaved forest, alpine vegetation, and cultural vegetation) with corresponding climatic factors. In 1982-2006, the NDVI, mean annual temperature, and annual precipitation had an overall increasing trend, and the drought index decreased. Particularly, the upward trend of mean annual temperature was statistically significant. Among the nine vegetation types, the NDVI of bush and mash decreased, and the downward trend was significant for bush. The NDVI of the other seven vegetation types increased, and the upward trend was significant for coniferous forest, meadow, and alpine vegetation, and extremely significant for shrub. The mean annual temperature in the areas with all the nine vegetation types increased significantly, while the annual precipitation had no significant change. The drought index in the areas with marsh, bush, and cultural vegetation presented an increasing trend, that in the areas with meadow and alpine vegetation decreased significantly, and this index in the areas with other four vegetation types had an unobvious decreasing trend. The NDVI of shrub and coniferous forest had a significantly positive correlation with mean annual temperature, and that of shrub and meadow had significantly negative correlation with drought index. Under the conditions of the other two climatic factors unchanged, the NDVI of coniferous forest, broad-leaved forest, and alpine vegetation showed the strongest correlation with mean annual temperature, that of grass showed the strongest correlation with annual precipitation, and the NDVI of mash, shrub, grass, meadow, and cultural

  13. Potential correlations of dentogenic factors to the development of clinically verified fungus balls: A retrospective computed tomography-based analysis.

    Science.gov (United States)

    Tomazic, Peter Valentin; Dostal, Eva; Magyar, Marton; Lang-Loidolt, Doris; Wolf, Axel; Koele, Wolfgang; Truschnegg, Astrid; Stammberger, Heinz; Payer, Michael

    2016-01-01

    Fungus balls are a common disease of the paranasal sinuses, usually involving the maxillary sinus. To clarify the pathology, we analyzed patients treated for maxillary sinus fungus balls to see whether the latter correlated with dentogenic factors. Retrospective case analysis. Cases of maxillary sinus fungus balls diagnosed between January 2000 and December 2013 were analyzed retrospectively. Patients' charts were reviewed for diagnosis, gender, and age. Paranasal sinus computed tomography (CT) scans were reviewed according to the side of the fungus ball, calcifications/opacifications, and dentogenic factors. In 98/102 patients (96.1%), 157 dentogenic factors could be identified on the side affected by a fungus ball. On the contralateral healthy side, there were 125 dentogenic factors. In four (3.9%) of the patients, no dentogenic pathology was identified on the CT scan. The presence of dentogenic factors (regardless of number) was significantly associated with a fungus ball compared to the healthy side (P = .024, χ(2) test, odds ratio: 2.72 [95% confidence interval: 1.02-7.23]). Dentogenic factors regardless of type potentially correlate with the presence of maxillary sinus fungus ball. Unlike the overall presence of dentogenic factors, the particular dentogenic factors in an individual patient do not significantly influence the development of fungus balls. After diagnosis of dentogenic pathology in penetrated maxillary sinus floors, patients should be closely monitored and informed about their higher risk of developing a fungus ball. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

  14. The role of frictional strength on plate coupling at the subduction interface

    KAUST Repository

    Tan, Eh

    2012-10-01

    At a subduction zone the amount of friction between the incoming plate and the forearc is an important factor in controlling the dip angle of subduction and the structure of the forearc. In this paper, we investigate the role of the frictional strength of sediments and of the serpentinized peridotite on the evolution of convergent margins. In numerical models, we vary thickness of a serpentinized layer in the mantle wedge (15 to 25km) and the frictional strength of both the sediments and serpentinized mantle (friction angle 1 to 15, or static friction coefficient 0.017 to 0.27) to control the amount of frictional coupling between the plates. With plastic strain weakening in the lithosphere, our numerical models can attain stable subduction geometry over millions of years. We find that the frictional strength of the sediments and serpentinized peridotite exerts the largest control on the dip angle of the subduction interface at seismogenic depths. In the case of low sediment and serpentinite friction, the subduction interface has a shallow dip, while the subduction zone develops an accretionary prism, a broad forearc high, a deep forearc basin, and a shallow trench. In the high friction case, the subduction interface is steep, the trench is deeper, and the accretionary prism, forearc high and basin are all absent. The resultant free-air gravity and topographic signature of these subduction zone models are consistent with observations. We believe that the low-friction model produces a geometry and forearc structure similar to that of accretionary margins. Conversely, models with high friction angles in sediments and serpentinite develop characteristics of an erosional convergent margin. We find that the strength of the subduction interface is critical in controlling the amount of coupling at the seismogenic zone and perhaps ultimately the size of the largest earthquakes at subduction zones. © 2012. American Geophysical Union. All Rights Reserved.

  15. Internal (Annular) and Compressible External (Flat Plate) Turbulent Flow Heat Transfer Correlations.

    Energy Technology Data Exchange (ETDEWEB)

    Dechant, Lawrence [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Smith, Justin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    Here we provide a discussion regarding the applicability of a family of traditional heat transfer correlation based models for several (unit level) heat transfer problems associated with flight heat transfer estimates and internal flow heat transfer associated with an experimental simulation design (Dobranich 2014). Variability between semi-empirical free-flight models suggests relative differences for heat transfer coefficients on the order of 10%, while the internal annular flow behavior is larger with differences on the order of 20%. We emphasize that these expressions are strictly valid only for the geometries they have been derived for e.g. the fully developed annular flow or simple external flow problems. Though, the application of flat plate skin friction estimate to cylindrical bodies is a traditional procedure to estimate skin friction and heat transfer, an over-prediction bias is often observed using these approximations for missile type bodies. As a correction for this over-estimate trend, we discuss a simple scaling reduction factor for flat plate turbulent skin friction and heat transfer solutions (correlations) applied to blunt bodies of revolution at zero angle of attack. The method estimates the ratio between axisymmetric and 2-d stagnation point heat transfer skin friction and Stanton number solution expressions for sub-turbulent Reynolds numbers %3C1x10 4 . This factor is assumed to also directly influence the flat plate results applied to the cylindrical portion of the flow and the flat plate correlations are modified by

  16. Coefficient of Friction at the Fingertips in Type II Diabetics Compared to Healthy Adults.

    Science.gov (United States)

    Thames, Beatriz H; Gorniak, Stacey L

    2017-07-01

    Clinical observations suggest that type II diabetes patients are more susceptible to skin changes, which may be associated with reduced coefficient of friction at the fingertips. Reduced coefficient of friction may explain recent reports of fine motor dysfunction in diabetic patients. Coefficient of friction was evaluated using slip force evaluation in a cross-sectional cohort of diabetic patients and age- and sex-matched healthy controls. Covariates of tactile sensation, disease duration, glycated hemoglobin, and clinical diagnosis of peripheral neuropathy were also assessed. A significant decrease in fingertip coefficient of friction in the diabetic group was found as compared to controls. Health state covariates did not alter the strength of between-group differences in statistical analyses. This finding of between-group differences for fingertip frictional properties suggests that causative factors of reported manual motor dysfunction lie in both the distal and proximal portions of the nervous system.

  17. An engineering approach to dry friction behaviour of numerous engineering plastics with respect to the mechanical properties

    Directory of Open Access Journals (Sweden)

    G. Kalacska

    2013-02-01

    Full Text Available Twenty-one different commercial-grade engineering polymers, including virgin and composite types, were selected for testing, based on mechanical engineering practices. Three groups were formed according to typical applications: 1 Sliding machine element materials; 2 Mechanically load-carrying machine element materials that are often subjected to friction and wear effects; and 3 Additional two amorphous materials used as chemically resistant materials that have rare sliding load properties. The friction running-in state was tested using a dynamic pin-on-plate test rig. During steady-state friction tests, two pv regimes (0.8 and 2 MPa"ms–1 were analysed by a pin-on-disc test system. Based on the measured forces on ground structural steel, surface friction coefficients were calculated and analysed with respect to the mechanical effects of friction. The friction results were evaluated by the measured mechanical properties: yield stress, Shore D hardness, Young’s modulus and elongation at the break. The three material groups exhibited different trends in friction with respect to changing mechanical properties. Linear (with varying positive and negative slopes, logarithmic and exponential relationships were observed, and occasionally there were no effects observed. At steady-state friction, the elongation at the break had less effect on the friction coefficients. The dynamic sliding model, which correlates better to real machine element applications, showed that increasing hardness and yield stress decreases friction. During steady-state friction, an increase in pv regime often changed the sign of the linear relationship between the material property and the friction, which agrees with the frictional theory of polymer/steel sliding pairs.

  18. Are Fit Indices Biased in Favor of Bi-Factor Models in Cognitive Ability Research?: A Comparison of Fit in Correlated Factors, Higher-Order, and Bi-Factor Models via Monte Carlo Simulations

    Directory of Open Access Journals (Sweden)

    Grant B. Morgan

    2015-02-01

    Full Text Available Bi-factor confirmatory factor models have been influential in research on cognitive abilities because they often better fit the data than correlated factors and higher-order models. They also instantiate a perspective that differs from that offered by other models. Motivated by previous work that hypothesized an inherent statistical bias of fit indices favoring the bi-factor model, we compared the fit of correlated factors, higher-order, and bi-factor models via Monte Carlo methods. When data were sampled from a true bi-factor structure, each of the approximate fit indices was more likely than not to identify the bi-factor solution as the best fitting. When samples were selected from a true multiple correlated factors structure, approximate fit indices were more likely overall to identify the correlated factors solution as the best fitting. In contrast, when samples were generated from a true higher-order structure, approximate fit indices tended to identify the bi-factor solution as best fitting. There was extensive overlap of fit values across the models regardless of true structure. Although one model may fit a given dataset best relative to the other models, each of the models tended to fit the data well in absolute terms. Given this variability, models must also be judged on substantive and conceptual grounds.

  19. IFCI 7.0 Models and Correlations

    Energy Technology Data Exchange (ETDEWEB)

    Reed, A.W.; Schmidt, R.C.; Young, M.F.

    1999-05-01

    The Integrated Fuel-Coolant Interaction Code (IFCI) is a best-estimate computer program for analysis of phenomena related to mixing of molten nuclear reactor core material with reactor coolant (water). The stand-alone version of the code, IFCI 7.0, has been designed for analysis of small- and intermediate-scale experiments in order to gain insight into the physics (including scaling effects) of molten fuel-coolant interactions. The code's methods, models, and correlations are being assessed. This report describes the flow regime, friction factor, and heat-transfer models used in the current version of IFCI (IFCI 7.0).

  20. Friction and wear performance of diamond-like carbon, boron carbide, and titanium carbide coatings against glass

    International Nuclear Information System (INIS)

    Daniels, B.K.; Brown, D.W.; Kimock, F.M.

    1997-01-01

    Protection of glass substrates by direct ion beam deposited diamond-like carbon (DLC) coatings was observed using a commercial pin-on-disk instrument at ambient conditions without lubrication. Ion beam sputter-deposited titanium carbide and boron carbide coatings reduced sliding friction, and provided tribological protection of silicon substrates, but the improvement factor was less than that found for DLC. Observations of unlubricated sliding of hemispherical glass pins at ambient conditions on uncoated glass and silicon substrates, and ion beam deposited coatings showed decreased wear in the order: uncoated glass>uncoated silicon>boron carbide>titanium carbide>DLC>uncoated sapphire. Failure mechanisms varied widely and are discussed. Generally, the amount of wear decreased as the sliding friction decreased, with the exception of uncoated sapphire substrates, for which the wear was low despite very high friction. There is clear evidence that DLC coatings continue to protect the underlying substrate long after the damage first penetrates through the coating. The test results correlate with field use data on commercial products which have shown that the DLC coatings provide substantial extension of the useful lifetime of glass and other substrates. copyright 1997 Materials Research Society

  1. Correlation between factors associated with the removable partial dentures use and Candida spp. in saliva.

    Science.gov (United States)

    Gusmão, João Milton Rocha; Ferreira dos Santos, Silvana Soleo; Neisser, Maximiliano Piero; Jorge, Antônio Olavo Cardoso; Faria, Ms Ivan

    2011-12-01

    To correlate the presence and number of Candida spp. in the saliva of wearers of removable partial dentures retained with precision attachments with the proportion of metal/acrylic resin present in the dentures. Saliva samples from 40 removable partial denture wearers (test) and one paired sample of individuals, non-wearers of any type of removable denture (control) were collected, seeded, and the colony forming units of Candida counted and identified. The metal/acrylic resin proportion of each denture was quantified, using silicone plates pressed over each denture. Candida spp. was found in the saliva of 80% of the individuals in the test group and 65% of the control, with C. albicans being the most prevalent species. The test group presented with the highest number of colony forming units of Candida per ml of saliva, and there was weak correlation between this number and the metal and resin area of the denture (Pearson's coefficient of correlation). Greater prevalence and a higher number of colony forming units of Candida per ml of saliva occurred in removable partial denture wearers (p = 0.04) with a weak positive correlation between the metal and resin area and the number of colony forming units of Candida per ml of saliva. However, this correlation was more significant for the area of resin. © 2010 The Gerodontology Society and John Wiley & Sons A/S.

  2. Flow Dominance and Factorization of Transverse Momentum Correlations in Pb-Pb Collisions at the LHC.

    Science.gov (United States)

    Adam, J; Adamová, D; Aggarwal, M M; Aglieri Rinella, G; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; Aiola, S; Akindinov, A; Alam, S N; Albuquerque, D S D; Aleksandrov, D; Alessandro, B; Alexandre, D; Alfaro Molina, R; Alici, A; Alkin, A; Alme, J; Alt, T; Altinpinar, S; Altsybeev, I; Alves Garcia Prado, C; An, M; Andrei, C; Andrews, H A; Andronic, A; Anguelov, V; Anson, C; Antičić, T; Antinori, F; Antonioli, P; Anwar, R; Aphecetche, L; Appelshäuser, H; Arcelli, S; Arnaldi, R; Arnold, O W; Arsene, I C; Arslandok, M; Audurier, B; Augustinus, A; Averbeck, R; Azmi, M D; Badalà, A; Baek, Y W; Bagnasco, S; Bailhache, R; Bala, R; Baldisseri, A; Baral, R C; Barbano, A M; Barbera, R; Barile, F; Barioglio, L; Barnaföldi, G G; Barnby, L S; Barret, V; Bartalini, P; Barth, K; Bartke, J; Bartsch, E; Basile, M; Bastid, N; Basu, S; Bathen, B; Batigne, G; Batista Camejo, A; Batyunya, B; Batzing, P C; Bearden, I G; Beck, H; Bedda, C; Behera, N K; Belikov, I; Bellini, F; Bello Martinez, H; Bellwied, R; Beltran, L G E; Belyaev, V; Bencedi, G; Beole, S; Bercuci, A; Berdnikov, Y; Berenyi, D; Bertens, R A; Berzano, D; Betev, L; Bhasin, A; Bhat, I R; Bhati, A K; Bhattacharjee, B; Bhom, J; Bianchi, L; Bianchi, N; Bianchin, C; Bielčík, J; Bielčíková, J; Bilandzic, A; Biro, G; Biswas, R; Biswas, S; Blair, J T; Blau, D; Blume, C; Bock, F; Bogdanov, A; Boldizsár, L; Bombara, M; Bonora, M; Book, J; Borel, H; Borissov, A; Borri, M; Botta, E; Bourjau, C; Braun-Munzinger, P; Bregant, M; Broker, T A; Browning, T A; Broz, M; Brucken, E J; Bruna, E; Bruno, G E; Budnikov, D; Buesching, H; Bufalino, S; Buhler, P; Buitron, S A I; Buncic, P; Busch, O; Buthelezi, Z; Butt, J B; Buxton, J T; Cabala, J; Caffarri, D; Caines, H; Caliva, A; Calvo Villar, E; Camerini, P; Capon, A A; Carena, F; Carena, W; Carnesecchi, F; Castillo Castellanos, J; Castro, A J; Casula, E A R; Ceballos Sanchez, C; Cerello, P; Cerkala, J; Chang, B; Chapeland, S; Chartier, M; Charvet, J L; Chattopadhyay, S; Chattopadhyay, S; Chauvin, A; Cherney, M; Cheshkov, C; Cheynis, B; Chibante Barroso, V; Chinellato, D D; Cho, S; Chochula, P; Choi, K; Chojnacki, M; Choudhury, S; Christakoglou, P; Christensen, C H; Christiansen, P; Chujo, T; Chung, S U; Cicalo, C; Cifarelli, L; Cindolo, F; Cleymans, J; Colamaria, F; Colella, D; Collu, A; Colocci, M; Conesa Balbastre, G; Conesa Del Valle, Z; Connors, M E; Contreras, J G; Cormier, T M; Corrales Morales, Y; Cortés Maldonado, I; Cortese, P; Cosentino, M R; Costa, F; Crkovská, J; Crochet, P; Cruz Albino, R; Cuautle, E; Cunqueiro, L; Dahms, T; Dainese, A; Danisch, M C; Danu, A; Das, D; Das, I; Das, S; Dash, A; Dash, S; De, S; De Caro, A; de Cataldo, G; de Conti, C; de Cuveland, J; De Falco, A; De Gruttola, D; De Marco, N; De Pasquale, S; De Souza, R D; Degenhardt, H F; Deisting, A; Deloff, A; Deplano, C; Dhankher, P; Di Bari, D; Di Mauro, A; Di Nezza, P; Di Ruzza, B; Diaz Corchero, M A; Dietel, T; Dillenseger, P; Divià, R; Djuvsland, Ø; Dobrin, A; Domenicis Gimenez, D; Dönigus, B; Dordic, O; Drozhzhova, T; Dubey, A K; Dubla, A; Ducroux, L; Duggal, A K; Dupieux, P; Ehlers, R J; Elia, D; Endress, E; Engel, H; Epple, E; Erazmus, B; Erhardt, F; Espagnon, B; Esumi, S; Eulisse, G; Eum, J; Evans, D; Evdokimov, S; Fabbietti, L; Fabris, D; Faivre, J; Fantoni, A; Fasel, M; Feldkamp, L; Feliciello, A; Feofilov, G; Ferencei, J; Fernández Téllez, A; Ferreiro, E G; Ferretti, A; Festanti, A; Feuillard, V J G; Figiel, J; Figueredo, M A S; Filchagin, S; Finogeev, D; Fionda, F M; Fiore, E M; Floris, M; Foertsch, S; Foka, P; Fokin, S; Fragiacomo, E; Francescon, A; Francisco, A; Frankenfeld, U; Fronze, G G; Fuchs, U; Furget, C; Furs, A; Fusco Girard, M; Gaardhøje, J J; Gagliardi, M; Gago, A M; Gajdosova, K; Gallio, M; Galvan, C D; Gangadharan, D R; Ganoti, P; Gao, C; Garabatos, C; Garcia-Solis, E; Garg, K; Garg, P; Gargiulo, C; Gasik, P; Gauger, E F; Gay Ducati, M B; Germain, M; Ghosh, P; Ghosh, S K; Gianotti, P; Giubellino, P; Giubilato, P; Gladysz-Dziadus, E; Glässel, P; Goméz Coral, D M; Gomez Ramirez, A; Gonzalez, A S; Gonzalez, V; González-Zamora, P; Gorbunov, S; Görlich, L; Gotovac, S; Grabski, V; Graczykowski, L K; Graham, K L; Greiner, L; Grelli, A; Grigoras, C; Grigoriev, V; Grigoryan, A; Grigoryan, S; Grion, N; Gronefeld, J M; Grosa, F; Grosse-Oetringhaus, J F; Grosso, R; Gruber, L; Grull, F R; Guber, F; Guernane, R; Guerzoni, B; Gulbrandsen, K; Gunji, T; Gupta, A; Gupta, R; Guzman, I B; Haake, R; Hadjidakis, C; Hamagaki, H; Hamar, G; Hamon, J C; Harris, J W; Harton, A; Hatzifotiadou, D; Hayashi, S; Heckel, S T; Hellbär, E; Helstrup, H; Herghelegiu, A; Herrera Corral, G; Herrmann, F; Hess, B A; Hetland, K F; Hillemanns, H; Hippolyte, B; Hladky, J; Horak, D; Hosokawa, R; Hristov, P; Hughes, C; Humanic, T J; Hussain, N; Hussain, T; Hutter, D; Hwang, D S; Ilkaev, R; Inaba, M; Ippolitov, M; Irfan, M; Isakov, V; Islam, M S; Ivanov, M; Ivanov, V; Izucheev, V; Jacak, B; Jacazio, N; Jacobs, P M; Jadhav, M B; Jadlovska, S; Jadlovsky, J; Jahnke, C; Jakubowska, M J; Janik, M A; Jayarathna, P H S Y; Jena, C; Jena, S; Jercic, M; Jimenez Bustamante, R T; Jones, P G; Jusko, A; Kalinak, P; Kalweit, A; Kang, J H; Kaplin, V; Kar, S; Karasu Uysal, A; Karavichev, O; Karavicheva, T; Karayan, L; Karpechev, E; Kebschull, U; Keidel, R; Keijdener, D L D; Keil, M; Mohisin Khan, M; Khan, P; Khan, S A; Khanzadeev, A; Kharlov, Y; Khatun, A; Khuntia, A; Kielbowicz, M M; Kileng, B; Kim, D W; Kim, D J; Kim, D; Kim, H; Kim, J S; Kim, J; Kim, M; Kim, M; Kim, S; Kim, T; Kirsch, S; Kisel, I; Kiselev, S; Kisiel, A; Kiss, G; Klay, J L; Klein, C; Klein, J; Klein-Bösing, C; Klewin, S; Kluge, A; Knichel, M L; Knospe, A G; Kobdaj, C; Kofarago, M; Kollegger, T; Kolojvari, A; Kondratiev, V; Kondratyeva, N; Kondratyuk, E; Konevskikh, A; Kopcik, M; Kour, M; Kouzinopoulos, C; Kovalenko, O; Kovalenko, V; Kowalski, M; Koyithatta Meethaleveedu, G; Králik, I; Kravčáková, A; Krivda, M; Krizek, F; Kryshen, E; Krzewicki, M; Kubera, A M; Kučera, V; Kuhn, C; Kuijer, P G; Kumar, A; Kumar, J; Kumar, L; Kumar, S; Kundu, S; Kurashvili, P; Kurepin, A; Kurepin, A B; Kuryakin, A; Kushpil, S; Kweon, M J; Kwon, Y; La Pointe, S L; La Rocca, P; Lagana Fernandes, C; Lakomov, I; Langoy, R; Lapidus, K; Lara, C; Lardeux, A; Lattuca, A; Laudi, E; Lavicka, R; Lazaridis, L; Lea, R; Leardini, L; Lee, S; Lehas, F; Lehner, S; Lehrbach, J; Lemmon, R C; Lenti, V; Leogrande, E; León Monzón, I; Lévai, P; Li, S; Li, X; Lien, J; Lietava, R; Lindal, S; Lindenstruth, V; Lippmann, C; Lisa, M A; Litichevskyi, V; Ljunggren, H M; Llope, W J; Lodato, D F; Loenne, P I; Loginov, V; Loizides, C; Loncar, P; Lopez, X; López Torres, E; Lowe, A; Luettig, P; Lunardon, M; Luparello, G; Lupi, M; Lutz, T H; Maevskaya, A; Mager, M; Mahajan, S; Mahmood, S M; Maire, A; Majka, R D; Malaev, M; Maldonado Cervantes, I; Malinina, L; Mal'Kevich, D; Malzacher, P; Mamonov, A; Manko, V; Manso, F; Manzari, V; Mao, Y; Marchisone, M; Mareš, J; Margagliotti, G V; Margotti, A; Margutti, J; Marín, A; Markert, C; Marquard, M; Martin, N A; Martinengo, P; Martinez, J A L; Martínez, M I; Martínez García, G; Martinez Pedreira, M; Mas, A; Masciocchi, S; Masera, M; Masoni, A; Mastroserio, A; Mathis, A M; Matyja, A; Mayer, C; Mazer, J; Mazzilli, M; Mazzoni, M A; Meddi, F; Melikyan, Y; Menchaca-Rocha, A; Meninno, E; Mercado Pérez, J; Meres, M; Mhlanga, S; Miake, Y; Mieskolainen, M M; Mihaylov, D; Mikhaylov, K; Milano, L; Milosevic, J; Mischke, A; Mishra, A N; Mishra, T; Miśkowiec, D; Mitra, J; Mitu, C M; Mohammadi, N; Mohanty, B; Montes, E; Moreira De Godoy, D A; Moreno, L A P; Moretto, S; Morreale, A; Morsch, A; Muccifora, V; Mudnic, E; Mühlheim, D; Muhuri, S; Mukherjee, M; Mulligan, J D; Munhoz, M G; Münning, K; Munzer, R H; Murakami, H; Murray, S; Musa, L; Musinsky, J; Myers, C J; Naik, B; Nair, R; Nandi, B K; Nania, R; Nappi, E; Naru, M U; Natal da Luz, H; Nattrass, C; Navarro, S R; Nayak, K; Nayak, R; Nayak, T K; Nazarenko, S; Nedosekin, A; Negrao De Oliveira, R A; Nellen, L; Nesbo, S V; Ng, F; Nicassio, M; Niculescu, M; Niedziela, J; Nielsen, B S; Nikolaev, S; Nikulin, S; Nikulin, V; Noferini, F; Nomokonov, P; Nooren, G; Noris, J C C; Norman, J; Nyanin, A; Nystrand, J; Oeschler, H; Oh, S; Ohlson, A; Okubo, T; Olah, L; Oleniacz, J; Oliveira Da Silva, A C; Oliver, M H; Onderwaater, J; Oppedisano, C; Orava, R; Oravec, M; Ortiz Velasquez, A; Oskarsson, A; Otwinowski, J; Oyama, K; Ozdemir, M; Pachmayer, Y; Pacik, V; Pagano, D; Pagano, P; Paić, G; Pal, S K; Palni, P; Pan, J; Pandey, A K; Panebianco, S; Papikyan, V; Pappalardo, G S; Pareek, P; Park, J; Park, W J; Parmar, S; Passfeld, A; Paticchio, V; Patra, R N; Paul, B; Pei, H; Peitzmann, T; Peng, X; Pereira, L G; Pereira Da Costa, H; Peresunko, D; Perez Lezama, E; Peskov, V; Pestov, Y; Petráček, V; Petrov, V; Petrovici, M; Petta, C; Pezzi, R P; Piano, S; Pikna, M; Pillot, P; Pimentel, L O D L; Pinazza, O; Pinsky, L; Piyarathna, D B; Płoskoń, M; Planinic, M; Pluta, J; Pochybova, S; Podesta-Lerma, P L M; Poghosyan, M G; Polichtchouk, B; Poljak, N; Poonsawat, W; Pop, A; Poppenborg, H; Porteboeuf-Houssais, S; Porter, J; Pospisil, J; Pozdniakov, V; Prasad, S K; Preghenella, R; Prino, F; Pruneau, C A; Pshenichnov, I; Puccio, M; Puddu, G; Pujahari, P; Punin, V; Putschke, J; Qvigstad, H; Rachevski, A; Raha, S; Rajput, S; Rak, J; Rakotozafindrabe, A; Ramello, L; Rami, F; Rana, D B; Raniwala, R; Raniwala, S; Räsänen, S S; Rascanu, B T; Rathee, D; Ratza, V; Ravasenga, I; Read, K F; Redlich, K; Rehman, A; Reichelt, P; Reidt, F; Ren, X; Renfordt, R; Reolon, A R; Reshetin, A; Reygers, K; Riabov, V; Ricci, R A; Richert, T; Richter, M; Riedler, P; Riegler, W; Riggi, F; Ristea, C; Rodríguez Cahuantzi, M; Røed, K; Rogochaya, E; Rohr, D; Röhrich, D; Ronchetti, F; Ronflette, L; Rosnet, P; Rossi, A; Roukoutakis, F; Roy, A; Roy, C; Roy, P; Rubio Montero, A J; Rui, R; Russo, R; Ryabinkin, E; Ryabov, Y; Rybicki, A; Saarinen, S; Sadhu, S; Sadovsky, S; Šafařík, K; Sahlmuller, B; Sahoo, B; Sahoo, P; Sahoo, R; Sahoo, S; Sahu, P K; Saini, J; Sakai, S; Saleh, M A; Salzwedel, J; Sambyal, S; Samsonov, V; Sandoval, A; Sarkar, D; Sarkar, N; Sarma, P; Sas, M H P; Scapparone, E; Scarlassara, F; Scharenberg, R P; Schiaua, C; Schicker, R; Schmidt, C; Schmidt, H R; Schmidt, M O; Schmidt, M; Schukraft, J; Schutz, Y; Schwarz, K; Schweda, K; Scioli, G; Scomparin, E; Scott, R; Šefčík, M; Seger, J E; Sekiguchi, Y; Sekihata, D; Selyuzhenkov, I; Senosi, K; Senyukov, S; Serradilla, E; Sett, P; Sevcenco, A; Shabanov, A; Shabetai, A; Shadura, O; Shahoyan, R; Shangaraev, A; Sharma, A; Sharma, A; Sharma, M; Sharma, M; Sharma, N; Sheikh, A I; Shigaki, K; Shou, Q; Shtejer, K; Sibiriak, Y; Siddhanta, S; Sielewicz, K M; Siemiarczuk, T; Silvermyr, D; Silvestre, C; Simatovic, G; Simonetti, G; Singaraju, R; Singh, R; Singhal, V; Sinha, T; Sitar, B; Sitta, M; Skaali, T B; Slupecki, M; Smirnov, N; Snellings, R J M; Snellman, T W; Song, J; Song, M; Soramel, F; Sorensen, S; Sozzi, F; Spiriti, E; Sputowska, I; Srivastava, B K; Stachel, J; Stan, I; Stankus, P; Stenlund, E; Stiller, J H; Stocco, D; Strmen, P; Suaide, A A P; Sugitate, T; Suire, C; Suleymanov, M; Suljic, M; Sultanov, R; Šumbera, M; Sumowidagdo, S; Suzuki, K; Swain, S; Szabo, A; Szarka, I; Szczepankiewicz, A; Szymanski, M; Tabassam, U; Takahashi, J; Tambave, G J; Tanaka, N; Tarhini, M; Tariq, M; Tarzila, M G; Tauro, A; Tejeda Muñoz, G; Telesca, A; Terasaki, K; Terrevoli, C; Teyssier, B; Thakur, D; Thomas, D; Tieulent, R; Tikhonov, A; Timmins, A R; Toia, A; Tripathy, S; Trogolo, S; Trombetta, G; Trubnikov, V; Trzaska, W H; Trzeciak, B A; Tsuji, T; Tumkin, A; Turrisi, R; Tveter, T S; Ullaland, K; Umaka, E N; Uras, A; Usai, G L; Utrobicic, A; Vala, M; Van Der Maarel, J; Van Hoorne, J W; van Leeuwen, M; Vanat, T; Vande Vyvre, P; Varga, D; Vargas, A; Vargyas, M; Varma, R; Vasileiou, M; Vasiliev, A; Vauthier, A; Vázquez Doce, O; Vechernin, V; Veen, A M; Velure, A; Vercellin, E; Vergara Limón, S; Vernet, R; Vértesi, R; Vickovic, L; Vigolo, S; Viinikainen, J; Vilakazi, Z; Villalobos Baillie, O; Villatoro Tello, A; Vinogradov, A; Vinogradov, L; Virgili, T; Vislavicius, V; Vodopyanov, A; Völkl, M A; Voloshin, K; Voloshin, S A; Volpe, G; von Haller, B; Vorobyev, I; Voscek, D; Vranic, D; Vrláková, J; Wagner, B; Wagner, J; Wang, H; Wang, M; Watanabe, D; Watanabe, Y; Weber, M; Weber, S G; Weiser, D F; Wessels, J P; Westerhoff, U; Whitehead, A M; Wiechula, J; Wikne, J; Wilk, G; Wilkinson, J; Willems, G A; Williams, M C S; Windelband, B; Witt, W E; Yalcin, S; Yang, P; Yano, S; Yin, Z; Yokoyama, H; Yoo, I-K; Yoon, J H; Yurchenko, V; Zaccolo, V; Zaman, A; Zampolli, C; Zanoli, H J C; Zaporozhets, S; Zardoshti, N; Zarochentsev, A; Závada, P; Zaviyalov, N; Zbroszczyk, H; Zhalov, M; Zhang, H; Zhang, X; Zhang, Y; Zhang, C; Zhang, Z; Zhao, C; Zhigareva, N; Zhou, D; Zhou, Y; Zhou, Z; Zhu, H; Zhu, J; Zhu, X; Zichichi, A; Zimmermann, A; Zimmermann, M B; Zimmermann, S; Zinovjev, G; Zmeskal, J

    2017-04-21

    We present the first measurement of the two-particle transverse momentum differential correlation function, P_{2}≡⟨Δp_{T}Δp_{T}⟩/⟨p_{T}⟩^{2}, in Pb-Pb collisions at sqrt[s_{NN}]=2.76  TeV. Results for P_{2} are reported as a function of the relative pseudorapidity (Δη) and azimuthal angle (Δφ) between two particles for different collision centralities. The Δϕ dependence is found to be largely independent of Δη for |Δη|≥0.9. In the 5% most central Pb-Pb collisions, the two-particle transverse momentum correlation function exhibits a clear double-hump structure around Δφ=π (i.e., on the away side), which is not observed in number correlations in the same centrality range, and thus provides an indication of the dominance of triangular flow in this collision centrality. Fourier decompositions of P_{2}, studied as a function of the collision centrality, show that correlations at |Δη|≥0.9 can be well reproduced by a flow ansatz based on the notion that measured transverse momentum correlations are strictly determined by the collective motion of the system.

  3. Preliminary investigation of plasma levels of sex hormones and human growth factor(s, and P300 latency as correlates to cognitive decline as a function of gender

    Directory of Open Access Journals (Sweden)

    Kerner Mallory M

    2009-07-01

    Full Text Available Abstract Background Aging is marked by declines in levels of many sex hormones and growth factors, as well as in cognitive function. The P300 event-related potential has been established as a predictor of cognitive decline. We decided to determine if this measure, as well as 2 standard tests of memory and attention, may be correlated with serum levels of sex hormones and growth factors, and if there are any generalizations that could be made based on these parameters and the aging process. Findings In this large clinically based preliminary study several sex-stratified associations between hormone levels and cognition were observed, including (1 for males aged 30 to 49, both IGF-1 and IGFBP-3 significantly associated negatively with prolonged P300 latency; (2 for males aged 30 to 49, the spearman correlation between prolonged P300 latency and low free testosterone was significant; (3 for males aged 60 to 69, there was a significant negative correlation between P300 latency and DHEA levels; (4 for females aged 50 to 59 IGFBP-3 significantly associated negatively with prolonged P300 latency; (5 for females at all age periods, estrogen and progesterone were uncorrelated with P300 latency; and (6 for females aged 40 to 69, there was significant negative correlation between DHEA levels and P300 latency. Moreover there were no statistically significant correlations between any hormone and Wechsler Memory Scale-III (WMS-111. However, in females, there was a significant positive correlation between estrogen levels and the number of Attention Deficit Disorder (ADD complaints. Conclusion Given certain caveats including confounding factors involving psychiatric and other chronic diseases as well as medications, the results may still have important value. If these results could be confirmed in a more rigorously controlled investigation, it may have important value in the diagnosis, prevention and treatment of cognitive impairments and decline.

  4. Internal friction in irradiated textolite

    International Nuclear Information System (INIS)

    Zajkin, Yu.A.; Kozhamkulov, B.A.; Koztaeva, U.P.

    1996-01-01

    Structural relaxation in irradiated textolite of ST and ST-EhTF trade marks presenting pressed material got by method of impregnation of fibreglass by phenole and epoxytriphenole binders relatively. Measuring of temperature dependences of internal friction (TDIF) is carried out in torsional pendulum at oscillation frequency 0.6-1.0 Hz before and after irradiation by stopped gamma-quanta with energy 3 MeV on electron accelerator EhLU-4. α and β peaks, related with segments motion in base and side chains of macromolecular have being observed on TDIF of all textolite. Growth of peaks height after irradiation evident about increase of segments mobility in base chain and about de-freezing of segments in side chains and it could be considered as qualitative measure of radiation destruction rate. Comparison of temperature dependences of internal friction indicates on higher radiation stability of textolite of ST-EhTF trade mark

  5. Friction and wear in sodium

    International Nuclear Information System (INIS)

    Hoffman, N.J.; Droher, J.J.

    1973-01-01

    In the design of a safe and reliable sodium-cooled reactor one of the more important problem areas is that of friction and wear of components immersed in liquid sodium or exposed to sodium vapor. Sodium coolant at elevated temperatures may severely affect most oxide-bearing surface layers which provide corrosion resistance and, to some extent, lubrication and surface hardness. Consequently, accelerated deterioration may be experienced on engaged-motion contact surfaces, which could result in unexpected reactor shutdown from component malfunction or failure due to galling and seizure. An overall view of the friction and wear phenomena encountered during oscillatory rubbing of surfaces in high-temperature, liquid-sodium environments is presented. Specific data generated at the Liquid Metal Engineering Center (LMEC) on this subject is also presented. (U.S.)

  6. Factors correlated with the reducibility of varus deformity in knee osteoarthritis: an analysis using navigation guided TKA.

    Science.gov (United States)

    Moon, Young Wan; Kim, Jae Gyoon; Han, Jung Hoon; Do, Kwan Hong; Seo, Jai Gon; Lim, Hong Chul

    2013-03-01

    We hypothesized that a number of clinical and radiologic parameters could influence the reducibility of varus deformity in total knee arthroplasty. The aim of this study was to identify the factors correlated with reducibility of varus deformity and predict more accurately the amount of medial soft tissue release required in varus deformity total knee arthroplasty. One hundred forty-three knees with preoperative varus alignment and medial osteoarthritis were included in this retrospective study. The total knee arthroplasties were performed using a navigation system (OrthoPilot) by single surgeon. To assess varus deformity, the authors measured preoperative mechanical axis angles and valgus stress angles. Mechanical tibial angles, mechanical femoral angles, femoral osteophyte sizes, and tibial osteophyte sizes were measured. The Ahlbäck grading scale was applied for radiologic parameters, and clinical parameters (age, body mass index, sex, duration of pain, and preoperative range of motion) were documented. Correlations between these factors and preoperative valgus stress angle were analyzed. A negative correlation was found between preoperative mechanical axis angle and preoperative valgus stress angle (p varus deformity and proximal tibial vara (measured by preoperative mechanical axis angle and mechanical tibial angle, respectively) are correlated with reducibility of varus deformity (measured by preoperative valgus stress angle), and clinical parameters (age, range of motion, duration of pain and body mass index) and other radiologic parameters (osteophyte size, severity of osteoarthritis and angulation of distal femoral joint surface) were not significantly correlated with reducibility of varus deformity.

  7. Effect of Sodium Fluoride Mouthwash on the Frictional Resistance of Orthodontic Wires

    Directory of Open Access Journals (Sweden)

    Allahyar Geramy

    2017-12-01

    Full Text Available Objectives: The friction between the brackets and orthodontic wire during sliding mechanics inflicts difficulties such as decreasing the applied force and tooth movement and also the loss of anchorage. Therefore, many studies have focused on the factors that affect the friction. The purpose of this study was to assess the effect of 0.05% sodium fluoride mouthwash on the friction between orthodontic brackets and wire.Materials and Methods: Four types of orthodontic wires including rectangular standard stainless steel (SS, titanium molybdenum alloy (TMA, nickel-titanium (NiTi and copper-nickel-titanium (Cu-NiTi were selected. In each group, half of the samples were immersed in 0.05% sodium fluoride mouthwash and the others were immersed in artificial saliva for 10 hours. An elastomeric ligature was used for ligating the wires to brackets. The frictional test was performed in a universal testing machine at the speed of 10 mm/minute. Two-way ANOVA was used for statistical analysis of the friction rate.Results: The friction rate was significantly higher after immersion in 0.05% sodium fluoride mouthwash in comparison with artificial saliva (P=0.00. Cu-NiTi wire showed the highest friction value followed by TMA, NiTi and SS wires.  Conclusions: According to the results of the current study, 0.05% sodium fluoride mouthwash increased the frictional characteristics of all the evaluated orthodontic wires.

  8. Effect of humidity and interlayer cation on frictional strength of montmorillonite

    Science.gov (United States)

    Tetsuka, H.; Katayama, I.; Sakuma, H.; Tamura, K.

    2016-12-01

    Smectite has been ubiquitously seen in fault gouge (Schleicher et al., 2006; Kuo et al., 2009; Si et al., 2014; Kameda, 2015) and is characteristic by low frictional coefficient (Saffer et al., 2001; Ikari et al., 2007); consequently, it has a key role in fault dynamics. The frictional strength of montmorillonite (a typical type of smectite) is affected by mainly two factors, 1) hydration state and 2) interlayer cation. Previous laboratory experiments have shown that the frictional strength of montmorillonite changes with hydration state (Ikari et al., 2007) and with interlayer cation (Behnsen and Faulkner, 2013). However, experimental study for frictional strengths of interlayer cation-exchanged montmorillonite under controlled hydration state has not been reported. We are developing humidity control system in biaxial friction testing machine and try to investigate the effect of relative humidity and interlayer cation on frictional strength of montmorillonite. The humidity control system consists of two units, 1) the pressure vessel (core holder) unit controlled by a constant temperature and 2) the vapor generating unit controlled by variable temperature. We control relative humidity around sample, which is calculated from the temperature around sample and the vapor pressure at vapor generating unit. Preliminary experiments under controlled humidity show frictional coefficient of montmorillonite decrease with increasing relative humidity. In the meeting, we will report the systematic study of frictional coefficient as function of relative humidity and interlayer cation species.

  9. Effect of Sodium Fluoride Mouthwash on the Frictional Resistance of Orthodontic Wires.

    Science.gov (United States)

    Geramy, Allahyar; Hooshmand, Tabassom; Etezadi, Tahura

    2017-09-01

    The friction between the brackets and orthodontic wire during sliding mechanics inflicts difficulties such as decreasing the applied force and tooth movement and also the loss of anchorage. Therefore, many studies have focused on the factors that affect the friction. The purpose of this study was to assess the effect of 0.05% sodium fluoride mouthwash on the friction between orthodontic brackets and wire. Four types of orthodontic wires including rectangular standard stainless steel (SS), titanium molybdenum alloy (TMA), nickel-titanium (NiTi) and copper-nickel-titanium (Cu-NiTi) were selected. In each group, half of the samples were immersed in 0.05% sodium fluoride mouthwash and the others were immersed in artificial saliva for 10 hours. An elastomeric ligature was used for ligating the wires to brackets. The frictional test was performed in a universal testing machine at the speed of 10 mm/minute. Two-way ANOVA was used for statistical analysis of the friction rate. The friction rate was significantly higher after immersion in 0.05% sodium fluoride mouthwash in comparison with artificial saliva (P=0.00). Cu-NiTi wire showed the highest friction value followed by TMA, NiTi and SS wires. According to the results of the current study, 0.05% sodium fluoride mouthwash increased the frictional characteristics of all the evaluated orthodontic wires.

  10. Static coefficient of friction between stainless steel and PMMA used in cemented hip and knee implants.

    Science.gov (United States)

    Nuño, N; Groppetti, R; Senin, N

    2006-11-01

    Design of cemented hip and knee implants, oriented to improve the longevity of artificial joints, is largely based on numerical models. The static coefficient of friction between the implant and the bone cement is necessary to characterize the interface conditions in these models and must be accurately provided. The measurement of this coefficient using a repeatable and reproducible methodology for materials used in total hip arthroplasty is missing from the literature. A micro-topographic surface analysis characterized the surfaces of the specimens used in the experiments. The coefficient of friction between stainless steel and bone cement in dry and wet conditions using bovine serum was determined using a prototype computerized sliding friction tester. The effects of surface roughness (polished versus matt) and of contact pressure on the coefficient of friction have also been investigated. The serum influences little the coefficient of friction for the matt steel surface, where the mechanical interactions due to higher roughness are still the most relevant factor. However, for polished steel surfaces, the restraining effect of proteins plays a very relevant role in increasing the coefficient of friction. When the coefficient of friction is used in finite element analysis, it is used for the debonded stem-cement situation. It can thus be assumed that serum will propagate between the stem and the cement mantle. The authors believe that the use of a static coefficient of friction of 0.3-0.4, measured in the present study, is appropriate in finite element models.

  11. Correlation between expression of LRP16, Ki67 and EGFR and breast cancer clinical pathologic factors and prognosis.

    Science.gov (United States)

    Yao, D-J; Qiao, S; Zhang, Y; Zhao, Y-T; Yuan, C-H

    2017-07-01

    To investigate the expression of leukemia-related protein 16 (LRP16), proliferating cell nuclear antigen K-67 (Ki67) and epidermal growth factor receptor-1 (EGFR-1) in breast cancer tissue and to explore the correlation between the expression of those proteins and breast cancer clinical pathologic factors and prognosis. The expressions of LRP16, Ki67 and EGFR in breast cancer tissues of 86 cases were detected by the immunohistochemical method and the correlations between the expression of LRP16, Ki67 and EGFR and clinical pathologic factors and prognosis were investigated. Positive expression rates of LRP16, Ki67 and EGFR in breast cancer tissue were 52.3%, 70.9% and 16.3%, respectively. There was no statistical difference in the expression of RP16, Ki67 and EGFR between different age groups (p>0.05). The expression of LRP16 was correlated with clinical stage, histological grade, tumor size and lymphatic metastasis (pKi67 was correlated with clinical stage, histological grade, tumor size and lymphatic metastasis (pKi67 positive group and negative group also showed statistically significant difference (pKi67 and EGFR in breast cancer tissue improves the understanding of biological behaviors of breast cancer, which in turn provide clinical guidance in diagnosis, treatment and prognosis assessment.

  12. Correlation of morphological pattern of optical coherence tomography in diabetic macular edema with systemic risk factors in middle aged males.

    Science.gov (United States)

    Ghosh, Sambuddha; Bansal, Preeti; Shejao, Harsha; Hegde, Raghuraj; Roy, Debesh; Biswas, Shyamapada

    2015-02-01

    To study correlation of different optical coherence tomography (OCT) patterns of diabetic macular edema (DME) with systemic risk factors. Institutional cross-sectional double-masked non-interventional study with 330 eyes of middle-aged male type 2 diabetes patients with DME. Various systemic parameters were measured. Diffuse retinal thickening (DRT), cystoid and serous patterns of DME were identified on OCT. Comparison between DRT versus non-DRT and serous versus non-serous eyes was done in respect to systemic parameters. Correlation of serous and DRT pattern was tested with systemic parameters above and below specified values. Mean age was 54.4 ± 7.1 years. Mean duration of diabetes was 8.7 ± 4.2 years. Mean serum globulin level was significantly higher (p = 0.018) in serous compared to non-serous group. Prevalence of serous DME was significantly high in those with serum globulin level >3.5 gm/dl (prevalence ratio = 3.01, p = 0.040). Significant correlation of central macular thickness was observed with duration of diabetes (p = 0.002, r = 0.440).Visual acuity (logMAR) was correlated significantly with HbA1C (p = 0.031, r = 0.305). Increased serum globulin, a positive phase reactant of inflammation, was found significant independent risk factor for development of serous DME. This study did not identify any modifiable systemic factor for any of the OCT patterns in DME.

  13. The Correlated Factors of Mandatory Social Reporting by Islamic Banks in Indonesia

    Directory of Open Access Journals (Sweden)

    Dodik Siswantoro

    2012-08-01

    penelitian ini adalah untuk memperkirakan Kemauan Membayar rumah tangga Muslim untuk berkontribusi wakaf tunai sebagai strategi menuju pengelolaan kekayaan di Sri Lanka. Wakaf secara bahasa menahan (harta yang ditekankan dalam Islam sebagai ibadah karena dapat mendistribusikan kekayaan di antara masyarakat Muslim dan akan membantu untuk mengembangkan visi Islam yaitu persaudaraan.Metode - Metode penilaian Kontingensi digunakan untuk memperkirakan Kesediaan membayar rumah tangga Muslim dalam meningkatkan status sosial - ekonomi masyarakat berpenghasilan rendah melalui pengelolaan kekayaan wakaf di Sri Lanka. Penelitian ini dikembangkan berdasarkan Teori Utilitas Acak.Hasil - Paper ini mengidentifikasi metode yang tepat untuk memperkirakan kemauan membayar rumah tangga Muslim di Sri Lanka untuk wakaf lembaga. Evaluasi tersebut sangat penting untuksistem keuangan Islam yang berfungsi secara efektif dalam rangka mencapai tujuan yang bermartabat keadilan sosial - ekonomi melalui distribusi kekayaan yang tepat.Kesimpulan - Paper ini menyajikan model konseptual lembaga wakaf yang akan berguna untuk penelitian empiris lebih lanjut di daerah ini. Temuan ini tidak hanya tepat dan berlaku untuk Sri Lanka, tetapi juga ke negara-negara Muslim dan non -Muslim lainnya. Ini adalah kontribusi yang unik untuk literatur ekonomi Islam. Pengetahuan yang diperoleh dari studi ini adalah mengharapkan agar wakaf tunai diusulkan untuk mengelola kekayaan dalam rangka meningkatkan status sosial - ekonomi masyarakat berpenghasilan rendah di Sri Lanka.Keywords: Awqaf, Contingent Valuation Method, Utility Theory, Willingness to Pay, Welfare Changes Objective – The purpose of this research is to analyze correlated factors related to social reporting by Islamic banks in Indonesia. According to the accounting standard in Indonesia, Islamic banks are legally required to report on social aspects. Social reporting is regulated in Indonesia under the accounting standard for Islamic Financial Institutions No

  14. Internal friction in uranium dioxide

    International Nuclear Information System (INIS)

    Paulin Filho, Pedro Iris

    1979-01-01

    The uranium dioxide inelastic properties were studied measuring internal friction at low frequencies (of the order of 1 Hz). The work was developed in the 160 to 400 deg C temperature range. The effect of stoichiometry variation was studied oxidizing the sample with consequent change of the defect structure originally present in the non-stoichiometric uranium dioxide. The presence of a wide and irregular peak due to oxidation was observed at low temperatures. Activation energy calculations indicated the occurrence of various relaxation processes and assuming the existence of a peak between - 80 and - 70 deg C , the absolute value obtained for the activation energy (0,54 eV) is consistent with the observed values determined at medium and high frequencies for the stress induced reorientation of defects. The microstructure effect on the inelastic properties was studied for stoichiometric uranium dioxide, by varying grain size and porosity. These parameters have influence on the high temperature measurements of internal friction. The internal friction variation for temperatures higher than 340 deg C is thought to be due to grain boundary relaxation phenomena. (author)

  15. Friction of elastomer-on-glass system and direct observation of its frictional interface

    International Nuclear Information System (INIS)

    Okamoto, Yoshihiro; Nishio, Kazuyuki; Sugiura, Jun-ichi; Hirano, Motohisa; Nitta, Takahiro

    2007-01-01

    We performed a study on the static friction of PDMS elastomers with well-defined surface topography sliding over glass. An experimental setup for simultaneous measurements of friction force and direct observations of frictional interface has been developed. The static friction force was nearly proportional to normal load. The static friction force was independent of stick time. The simultaneous measurements revealed that the static friction force was proportional to the total area of contact. The coefficient was nearly independent of the surface topography of PDMS elastomers

  16. Nano-friction behavior of phosphorene

    Science.gov (United States)

    Bai, Lichun; Liu, Bo; Srikanth, Narasimalu; Tian, Yu; Zhou, Kun

    2017-09-01

    Nano-friction of phosphorene plays a significant role in affecting the controllability and efficiency of applying strain engineering to tune its properties. So far, the friction behavior of phosphorene has not been studied. This work studies the friction of single-layer and bilayer phosphorene on an amorphous silicon substrate by sliding a rigid tip. For the single-layer phosphorene, it is found that its friction is highly anisotropic, i.e. the friction is larger along the armchair direction than that along the zigzag direction. Moreover, pre-strain of the phosphorene also exhibits anisotropic effects. The friction increases with the pre-strain along the zigzag direction, but decreases with that along the armchair direction. Furthermore, the strong adhesion between the phosphorene and its substrate increases the friction between the phosphorene and the tip. For bilayer phosphorene, its friction highly depends on its stacking mode, which determines the contact interface with a commensurate or incommensurate pattern. This friction behavior is quite unique and greatly differs from that of graphene and molybdenum disulfide. Detailed analysis reveals that this behavior results from the combination effect of the friction contact area, the potential-energy profile of phosphorene, and its unique elongation.

  17. Molecular profile of major growth factors in lumbar intervertebral disc herniation: Correlation with patient clinical and epidemiological characteristics

    Science.gov (United States)

    Tsarouhas, Alexandros; Soufla, Giannoula; Tsarouhas, Konstantinos; Katonis, Pavlos; Pasku, Dritan; Vakis, Antonis; Tsatsakis, Aristides M.; Spandidos, Demetrios A.

    2017-01-01

    The involvement of growth factors (GFs) in the pathogenesis of lumbar intervertebral disc (ID) herniation and the spontaneous resorption of herniated ID fragments remains only partially elucidated. A simultaneous assessment of the transcript levels of numerous GFs and their association with clinical and epidemiological profiles of human ID herniation would provide valuable insight into the biology and clinical course of the disease. In the present study, we examined simultaneously the transcript levels of vascular endothelial growth factor (VEGF), transforming growth factor β1 (TGF-β1), basic fibroblast growth factor 2 (bFGF2), platelet derived growth factor (PDGF) isoforms and receptors, epidermal growth factor (EGF) and insulin growth factor-1 (IGF-1) in herniated and control ID specimens and investigated their correlation with the clinicopathological profiles of patients suffering from symptomatic lumbar ID herniation. GF mRNA expression levels were determined by RT-qPCR in 63 surgical specimens from lumbar herniated discs and 10 control ID specimens. Multiple positive correlations were observed between the transcript levels of the GFs examined in the ID herniation group. VEGF mRNA expression was significantly increased in the protruding compared with the extruded discs. Intense and acute pain significantly upregulated the PDGF transcript levels. Significant negative correlations were observed between the patient body mass index and the transcript levels of VEGF and PDGF receptors. Our findings support the hypothesis of the involvement of GFs in the natural history of ID herniation. GFs synergistically act in herniated IDs. Increased VEGF expression possibly induces the neovascularization process in the earliest stages of ID herniation. PDGF-C and -D play a role in the acute phase of radiculopathy in a metabolic response for tissue healing. A molecular effect, in addition to the biomechanical effect of obesity in the pathogenesis of ID herniation is also

  18. An examination of the correlation amongst trunk flexibility, x-factor and clubhead speed in skilled golfers.

    Science.gov (United States)

    Joyce, Christopher

    2017-10-01

    Skilled golfers are reported to be more flexible than lesser able golfers, which may assist in increased x-factor (shoulder-pelvis separation) at the top of the backswing. However, it is unknown if increased flexibility produces faster clubhead speed. The aim of this study was to investigate the correlations amongst trunk flexibility and x-factor, as well as the association between flexibility and clubhead speed in low handicap golfers. Fifteen low handicap male golfers who displayed a modern swing, had their trunk static anatomical end-range of motion (flexibility) and driver swing kinematics were measured. Although Pearson correlations revealed trunk extension and lateral bending were moderately related to x-factor, axial rotation flexibility was not. A generalised linear model (GLM) reported three axial rotation flexibility variables, and six golf swing kinematic variables were associated with faster clubhead speed. The Pearson correlation results suggest that skilled golfers who have increased axial rotation flexibility do not necessarily utilise it to increase x-factor, and the GLM results support the importance of multisegment flexibility and interaction for improving golf performance with skilled golfers.

  19. Studies on correlation of positive surgical margin with clinicopathological factors and prognoses in breast conserving surgery

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Reiki; Nagao, Kazuharu; Miyayama, Haruhiko [Kumamoto City Hospital (Japan)

    1999-09-01

    Out of 484 cases with breast conserving surgery between April 1989 and March 1999, surgical procedures of 34 cases were changed to total mastectomy due to positive surgical margins. In this study we evaluated a clinical significance of surgical margin in relation to clinicopathological factors and prognoses. Ninety-nine cases (20.5%) had positive margins that were judged when cancer cells existed within 5 mm from margin. In multivariate analysis of factors for surgical margin, EIC-comedo status, ly, located site, proliferative activity, and age were significant and independent factors. Regarding local recurrence, positive margin, age, ER and proliferative activity were significant factors in multivariate analysis, especially in cases not receiving postoperative radiation therapy. Radiation therapy may be beneficial for patients with positive surgical margin. And patients with breast recurrence alone had significantly higher survival rates. Therefore, it is suggested that surgical margin may not reflect survival, although it is a significant factor for local recurrence. (author)

  20. Spatial correlations of population and ecological factors with distribution of visceral leishmaniasis cases in southwestern Iran.

    Science.gov (United States)

    Ghatee, Mohammad Amin; Sharifi, Iraj; Haghdoost, Ali Akbar; Kanannejad, Zahra; Taabody, Zahra; Hatam, Gholamreza; Abdollahipanah, Abbas

    2013-09-01

    Leishmaniasis as a dynamic disease may be markedly influenced by demographic and ecological factors. A geospatial information system study was developed to determine the distribution of visceral leishmaniasis (VL) cases in relation to population, climatic and environmental factors in Fars province, southwest of Iran. The dwelling addresses of 217 VL patients were obtained from hospital files. A hazard map produced by unifying buffers (5 km) around nomads travel routes (NTR) was developed to survey the effect of close proximity to NTR on the distribution of VL. Mean annual rainfall (MAR), mean annual temperature (MAT), four months temperature mean (T4), elevation, slope and landcover were climatic and environmental factors that have been analysed. Finally, data of dwelling foci were extracted from maps and analysed using logistic regression models. Close proximity to NTR was the most important factor influenced on the disease distribution. Climatic factors were in second rank. Among them, temperature especially T4 is the most effective variable and rainfall was also shown to be another effective climatic agent. Most cases of VL were reported from temperate and semiarid areas in western and central regions while arid condition was a confined factor. The environmental factor of landcovers including urban, dry farm and thin forest regions was revealed as the third rank effective factor. Altitude importance was only shown when its effect was studied independently from other factors. These findings present the distribution of VL in Fars province is influenced by combination of ecological and nomads demographical variables although closeness to NTR and nomads role in distribution and continuance of kala-azar are the most important factors.

  1. Correlation analysis of lung cancer and urban spatial factor: based on survey in Shanghai.

    Science.gov (United States)

    Wang, Lan; Zhao, Xiaojing; Xu, Wangyue; Tang, Jian; Jiang, Xiji

    2016-09-01

    The density of particulate matter (PM) in mega-cities in China such as Beijing and Shanghai has exceeded basic standards for health in recent years. Human exposure to PMs has been identified as traceable and controllable factor among all complicated risk factors for lung cancer. While the improvement of air quality needs tremendous efforts and time, certain revision of PM's density might happen associated with the adjustment of built environment. It is also proved that urban built environment is directly relevant to respiratory disease. Studies have respectively explored the indoor and outdoor factors on respiratory diseases. More comprehensive spatial factors need to be analyzed to understand the cumulative effect of built environment upon respiratory system. This interdisciplinary study examines the impact of both indoor (including age of housing, interval after decoration, indoor humidity etc.) and outdoor spatial factors (including density, parking, green spaces etc.) on lung cancer. A survey of lung cancer patients and a control group has been conducted in 2014 and 2015. A total of 472 interviewees are randomly selected within a pool of local residents who have resided in Shanghai for more than 5 years. Data are collected including their socio-demographic factors, lifestyle factors, and external and internal residential area factors. Regression models are established based on collected data to analyze the associations between lung cancer and urban spatial factors. Regression models illustrate that lung cancer presents significantly associated with a number of spatial factors. Significant outdoor spatial factors include external traffic volume (P=0.003), main plant type (P=0.035 for trees) of internal green space, internal water body (P=0.027) and land use of surrounding blocks (P=0.005 for residential areas of 7-9 floors, P=0.000 for residential areas of 4-6 floors, P=0.006 for business/commercial areas over 10 floors, P=0.005 for business/commercial areas of

  2. Correlation of adiposity indices with cardiovascular disease risk factors in healthy adults of Singapore: a cross-sectional study.

    Science.gov (United States)

    Bi, Xinyan; Tey, Siew Ling; Leong, Claudia; Quek, Rina; Loo, Yi Ting; Henry, Christiani Jeyakumar

    2016-01-01

    Obesity has long been highlighted for its association with increased incidence of cardiovascular disease (CVD). Nonetheless, the best adiposity indices to evaluate the CVD risk factors remain contentious and few studies have been performed in Asian populations. In the present study, we compared the association strength of percent body fat (PBF) to indirect anthropometric measures of general adiposity (body mass index (BMI) and body adiposity index (BAI)) and central adiposity (waist circumference (WC), and waist-to-hip ratio (WHR)) for the prediction of CVD risk factors in healthy men and women living in Singapore. A total of 125 individuals (63 men and 62 women) took part in this study. PBF was measured by using three different techniques, including bioelectrical impedance analysis (BIA), BOD POD, and dual-energy X-ray absorptiometry (DEXA). Anthropometric measurements (WC, hip circumference (HC), height, and weight), fasting blood glucose (FBG), fasting serum insulin (FSI), and lipid profiles were determined according to standard protocols. Correlations of anthropometric measurements and PBF with CVD risk factors were compared. Irrespective of the measuring techniques, PBF showed strong positive correlations with FSI, HOMA-IR, TC/HDL, TG/HDL, and LDL/HDL in both genders. While PBF was highly correlated with FBG, SBP, and DBP in females, no significant relationships were observed in males. Amongst the five anthropometric measures of adiposity, BAI was the best predictor for CVD risk factors in female participants (r = 0.593 for HOMA-IR, r = 0.542 for TG/HDL, r = 0.474 for SBP, and r = 0.448 for DBP). For males, the combination of WC (r = 0.629 for HOMA-IR, and r = 0.446 for TG/HDL) and WHR (r = 0.352 for SBP, and r = 0.366 for DBP) had the best correlation with CVD risk factors. Measurement of PBF does not outperform the simple anthropometric measurements of obesity, i.e. BAI, WC, and WHR, in the prediction of CVD risk factors in

  3. Preliminary investigation of plasma levels of sex hormones and human growth factor(s), and P300 latency as correlates to cognitive decline as a function of gender

    OpenAIRE

    Kerner Mallory M; Chen Amanda LC; Chen Thomas JH; Braverman Eric R; Tung Howard; Waite Roger L; Schoolfield John; Blum Kenneth

    2009-01-01

    Abstract Background Aging is marked by declines in levels of many sex hormones and growth factors, as well as in cognitive function. The P300 event-related potential has been established as a predictor of cognitive decline. We decided to determine if this measure, as well as 2 standard tests of memory and attention, may be correlated with serum levels of sex hormones and growth factors, and if there are any generalizations that could be made based on these parameters and the aging process. Fi...

  4. Coseismic slip and early afterslip of the 2015 Illapel, Chile, earthquake: Implications for frictional heterogeneity and coastal uplift

    Science.gov (United States)

    Barnhart, William D.; Murray, Jessica R.; Briggs, Richard W.; Gomez, Francisco; Miles, Charles P. J.; Svarc, Jerry L.; Riquelme, Sebástian; Stressler, Bryan J.

    2016-01-01

    Great subduction earthquakes are thought to rupture portions of the megathrust, where interseismic coupling is high and velocity-weakening frictional behavior is dominant, releasing elastic deformation accrued over a seismic cycle. Conversely, postseismic afterslip is assumed to occur primarily in regions of velocity-strengthening frictional characteristics that may correlate with lower interseismic coupling. However, it remains unclear if fixed frictional properties of the subduction interface, coseismic or aftershock-induced stress redistribution, or other factors control the spatial distribution of afterslip. Here we use interferometric synthetic aperture radar and Global Position System observations to map the distribution of coseismic slip of the 2015 Mw 8.3 Illapel, Chile, earthquake and afterslip within the first 38 days following the earthquake. We find that afterslip overlaps the coseismic slip area and propagates along-strike into regions of both high and moderate interseismic coupling. The significance of these observations, however, is tempered by the limited resolution of geodetic inversions for both slip and coupling. Additional afterslip imaged deeper on the fault surface bounds a discrete region of deep coseismic slip, and both contribute to net uplift of the Chilean Coastal Cordillera. A simple partitioning of the subduction interface into regions of fixed frictional properties cannot reconcile our geodetic observations. Instead, stress heterogeneities, either preexisting or induced by the earthquake, likely provide the primary control on the afterslip distribution for this subduction zone earthquake. We also explore the occurrence of coseismic and postseismic coastal uplift in this sequence and its implications for recent hypotheses concerning the source of permanent coastal uplift along subduction zones.

  5. Friction coefficient dependence on electrostatic tribocharging.

    Science.gov (United States)

    Burgo, Thiago A L; Silva, Cristiane A; Balestrin, Lia B S; Galembeck, Fernando

    2013-01-01

    Friction between dielectric surfaces produces patterns of fixed, stable electric charges that in turn contribute electrostatic components to surface interactions between the contacting solids. The literature presents a wealth of information on the electronic contributions to friction in metals and semiconductors but the effect of triboelectricity on friction coefficients of dielectrics is as yet poorly defined and understood. In this work, friction coefficients were measured on tribocharged polytetrafluoroethylene (PTFE), using three different techniques. As a result, friction coefficients at the macro- and nanoscales increase many-fold when PTFE surfaces are tribocharged, but this effect is eliminated by silanization of glass spheres rolling on PTFE. In conclusion, tribocharging may supersede all other contributions to macro- and nanoscale friction coefficients in PTFE and probably in other insulating polymers.

  6. Friction and Wear in Timing Belt Drives

    Directory of Open Access Journals (Sweden)

    B. Stojanovic

    2010-09-01

    Full Text Available Timing belt tooth goes into contact with a drive pulley, stretched to the maximum, because of the previous tension. When the contact begins the peak of the belt tooth makes the contact with the outer surface of the pulley teeth. The process of the teeth entering into the contact zone is accompanied with the relative sliding of their side surfaces and appropriate friction force. The normal force value is changing with the parabolic function, which also leads to the changes of the friction force. The biggest value of the normal force and of the friction force is at the tooth root. Hollow between teeth and the tip of the pulley teeth are also in contact. Occasionally, the face surface of the belt and the flange are also in contact. The friction occurs in those tribomechanical systems, also. Values of these friction forces are lower compared with the friction force, which occurs at the teeth root.

  7. Static friction between rigid fractal surfaces.

    Science.gov (United States)

    Alonso-Marroquin, Fernando; Huang, Pengyu; Hanaor, Dorian A H; Flores-Johnson, E A; Proust, Gwénaëlle; Gan, Yixiang; Shen, Luming

    2015-09-01

    Using spheropolygon-based simulations and contact slope analysis, we investigate the effects of surface topography and atomic scale friction on the macroscopically observed friction between rigid blocks with fractal surface structures. From our mathematical derivation, the angle of macroscopic friction is the result of the sum of the angle of atomic friction and the slope angle between the contact surfaces. The latter is obtained from the determination of all possible contact slopes between the two surface profiles through an alternative signature function. Our theory is validated through numerical simulations of spheropolygons with fractal Koch surfaces and is applied to the description of frictional properties of Weierstrass-Mandelbrot surfaces. The agreement between simulations and theory suggests that for interpreting macroscopic frictional behavior, the descriptors of surface morphology should be defined from the signature function rather than from the slopes of the contacting surfaces.

  8. An investigation of correlation factors linking footing resistance on sand with cone penetration test results

    OpenAIRE

    Gavin, Kenneth; Tolooiyan, Ali

    2012-01-01

    Significant research effort has led to improvements in our ability to estimate the ultimate bearing resistance of footings in sand. These techniques often estimate the footing resistance at relatively large displacements, typically 10% of the footing width, qb0.1. Cone Penetration Test (CPT) design methods typically link qb0.1 and qc through a constant reduction factor, a. A range of a factors for shallow footings have been proposed, some methods suggest that a is constant and while ...

  9. Gender Differences in Coronary Artery Disease: Correlational Study on Dietary Pattern and Known Cardiovascular Risk Factors

    OpenAIRE

    Najafi, Mahdi; Sheikhvatan, Mehrdad

    2013-01-01

    Background: The relationship between diet and cardiovascular risk factors in men and women with Coronary Artery Disease (CAD) has been the subject of recent studies. We studied a group of Iranian CAD patients to analyze any relationship between diet and CAD risk factors based on gender. Methods: In this study, 461 consecutive patients were assessed before their planned isolated coronary artery bypass graft surgery. They were interviewed to obtain the quantity and components of nutrients a...

  10. Initial estimation of correlation between estrogen receptor status and histopathology, and also some selected prognostic factors in breast cancer patients

    International Nuclear Information System (INIS)

    Cwikla, J.; Badowski, J.; Shafie, D.; Gugala, K.; Koziorowski, M.

    1996-01-01

    The goal of this study was to assess the correlation between estrogen receptor (ER) status and histopathology findings, likewise to assess some selected prognostic factors in patients with breast cancer. The study was carried out on 126 patients with breast cancer. ER concentration was estimated by the standard biochemical assay (DCC-dextran-coated charcoal assay). The correlation between established risk factors like: lymph node status; age menopausal status and ER status were analysed.The ER yielded in 61% positive results. The mean value of ER in invasive ductal carcinoma was 43.9 fmol/mg protein and the mean value of ER in invasive lobular carcinoma 51.4 fmol/mg protein. The significant statistics negative correlation between ER status of pre-menopausal patients with ductal breast carcinoma and regional lymph nodes involvement was found. There was no difference between ER status and histological type of the cancer. No correlation was found between ER status and age of patients. (author)

  11. Latency of auditory P300 correlates with self-control as measured by the Sixteen Personality Factor Questionnaire.

    Science.gov (United States)

    Lee, Heon-Jeong; Kim, Leen; Han, Chang-Su; Kim, Yong-Ku; Kim, Seung-Hyun; Lee, Min-Soo; Joe, Sook-Haeng; Jung, In-Kwa

    2005-08-01

    The reception, processing, and storage of information about experience define personality. The present study investigated the relationship between auditory event-related potentials (AERP) and personality traits. The AERP were recorded using a standard auditory oddball paradigm, and personality was evaluated by Cattell's Sixteen Personality Factor Questionnaire (16PF) in 20 healthy young male subjects. The P300 latency was found to be significantly associated with rule consciousness (factor G in the 16PF), perfectionism (factor Q3), and self-control (factor SC): it was negatively correlated with G score (r = -0.56, P = 0.01), Q3 score (r = -0.67, P = 0.001), and SC score (r = -0.65, P = 0.002). Moreover, the P300 amplitude and N100 amplitude were negatively correlated with reasoning (factor B; r = -0.46, P = 0.044; and r = -0.72, P = 0.002, respectively). These results indicate that the personality traits of self-control, perfectionism, high superego, and reasoning are related to information processing in the brain.

  12. Steroid response as prognostic factor and its correlation with molecular assessment of childhood acute lymphoblastic leukemia

    Directory of Open Access Journals (Sweden)

    Murti Andriastuti

    2015-12-01

    Full Text Available Background: Survival rate of children with acute lymphoblastic leukemia  (ALL in Indonesia remains low. Risk stratification accuracy is important to improve survival. In developed countries, risk stratification is determined based on gene fusion that is known related to steroid resistency. Steroid response at day-8 correlates with prognosis. The assessment can be applied in centers that cannot perform molecular assessment. This study aims to evaluate whether steroid response correlated to molecular assessment. Methods: A cross-sectional study was performed at Child Health Department, Cipto Mangunkusumo Hospital (January 2013-March 2014, a total of 73 patients were enrolled. Steroid was given for 7 days. Peripheral blast count at day 8 was evaluated, good response if blast count <1000 /µL and poor if  ≥1000 /µL. Fusion gene detection was also performed. The data was analysed using Statistical Package for Social Sciences (SPSS version 20.0.Results: Fusion gene was detected in 45 patients. In 1–10 years age group, 26/32 (81% subjects had good response, while 75% in <1 year age group and 7/9 (78% in ≥10 years age group had poor response. 5/7 (71% subjetcs had leukocyte count >100,000 /µL and 7/8 (88% with T-cell showed poor response. Age, leukocyte count, and T-cell were statistically correlated with steroid response (p<0.05. E2A-PBX1 fusion gene was the most common 19/45 (42%, followed by TEL-AML1 17/45 (38%, BCR-ABL 5/45 (17%, and MLL-AF4 1/45 (3%. Four of five subjects (80% with BCR-ABL and one subject with MLL-AF4 had poor steroid response. On the other hand, 12/19 (63% with E2A-PBX1 and 13/17 (77% with TEL-AML1 had good response. There was no correlation between steroid response and molecular assessment.Conclusion: Steroid response correlates with age, leukocyte count, and T-cell  but  not with molecular assessment.

  13. Flow Function of Pharmaceutical Powders Is Predominantly Governed by Cohesion, Not by Friction Coefficients.

    Science.gov (United States)

    Leung, Lap Yin; Mao, Chen; Srivastava, Ishan; Du, Ping; Yang, Chia-Yi

    2017-07-01

    The purpose of this study was to demonstrate that the flow function (FFc) of pharmaceutical powders, as measured by rotational shear cell, is predominantly governed by cohesion but not friction coefficients. Driven by an earlier report showing an inverse correlation between FFc and the cohesion divided by the corresponding pre-consolidation stress (Wang et al. 2016. Powder Tech. 294:105-112), we performed analysis on a large data set containing 1130 measurements from a ring shear tester and identified a near-perfect inverse correlation between the FFc and cohesion. Conversely, no correlation was found between FFc and friction angles. We also conducted theoretical analysis and estimated such correlations based on Mohr-Coulomb failure model. We discovered that the correlation between FFc and cohesion can sustain as long as the angle of internal friction at incipient flow is not significantly larger than the angle of internal friction at steady-state flow, a condition covering almost all pharmaceutical powders. The outcome of this study bears significance in pharmaceutical development. Because the cohesion value is strongly influenced by the interparticle cohesive forces, this study effectively shows that it is more efficient to improve the pharmaceutical powder flow by lowering the interparticle cohesive forces than by lowering the interparticle frictions. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  14. Friction Forces during Sliding of Various Brackets for Malaligned Teeth: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Vito Crincoli

    2013-01-01

    Full Text Available Aims. To measure the friction force generated during sliding mechanics with conventional, self-ligating (Damon 3 mx, Smart Clip, and Time 3 and low-friction (Synergy brackets using different archwire diameters and ligating systems in the presence of apical and buccal malalignments of the canine. Methods. An experimental setup reproducing the right buccal segment of the maxillary arch was designed to measure the friction force generated at the bracket/wire and wire/ligature interfaces of different brackets. A complete factorial plan was drawn up and a three-way analysis of variance (ANOVA was carried out to investigate whether the following factors affect the values of friction force: (i degree of malalignment, (ii diameter of the orthodontic wire, and (iii bracket/ligature combination. Tukey post hoc test was also conducted to evaluate any statistically significant differences between the bracket/ligature combinations analyzed. Results. ANOVA showed that all the above factors affect the friction force values. The friction force released during sliding mechanics with conventional brackets is about 5-6times higher than that released with the other investigated brackets. A quasilinear increase of the frictional forces was observed for increasing amounts of apical and buccal malalignments. Conclusion. The Synergy bracket with silicone ligature placed around the inner tie-wings appears to yield the best performance.

  15. Canonical correlation analysis of infant's size at birth and maternal factors: a study in rural northwest Bangladesh.

    Directory of Open Access Journals (Sweden)

    Alamgir Kabir

    Full Text Available This analysis was conducted to explore the association between 5 birth size measurements (weight, length and head, chest and mid-upper arm [MUAC] circumferences as dependent variables and 10 maternal factors as independent variables using canonical correlation analysis (CCA. CCA considers simultaneously sets of dependent and independent variables and, thus, generates a substantially reduced type 1 error. Data were from women delivering a singleton live birth (n = 14,506 while participating in a double-masked, cluster-randomized, placebo-controlled maternal vitamin A or β-carotene supplementation trial in rural Bangladesh. The first canonical correlation was 0.42 (P<0.001, demonstrating a moderate positive correlation mainly between the 5 birth size measurements and 5 maternal factors (preterm delivery, early pregnancy MUAC, infant sex, age and parity. A significant interaction between infant sex and preterm delivery on birth size was also revealed from the score plot. Thirteen percent of birth size variability was explained by the composite score of the maternal factors (Redundancy, RY/X = 0.131. Given an ability to accommodate numerous relationships and reduce complexities of multiple comparisons, CCA identified the 5 maternal variables able to predict birth size in this rural Bangladesh setting. CCA may offer an efficient, practical and inclusive approach to assessing the association between two sets of variables, addressing the innate complexity of interactions.

  16. Factor analysis of temperament and personality traits in bipolar patients: Correlates with comorbidity and disorder severity.

    Science.gov (United States)

    Qiu, Frank; Akiskal, Hagop S; Kelsoe, John R; Greenwood, Tiffany A

    2017-01-01

    Temperament and personality traits have been suggested as endophenotypes for bipolar disorder based on several lines of evidence, including heritability. Previous work suggested an anxious-reactive factor identified across temperament and personality inventories that produced significant group discrimination and could potentially be useful in genetic analyses. We have attempted to further characterize this factor structure in a sample of bipolar patients. A sample of 1195 subjects with bipolar I disorder was evaluated, all with complete data available. Dimension reduction across two inventories identified 18 factors explaining 39% of the variance. The two largest factors reflected affective instability and general anxiety/worry, respectively. Subsequent analyses of the clinical features associated with bipolar disorder revealed specificity for the factors in a predictable pattern. Cluster analysis of the factors identified a subgroup defined by a strong lack of general anxiety and low affective instability represented by the first two factors. The remaining subjects could be distinguished into two clusters by the presence of either more positive characteristics, including persistence/drive, spirituality, expressivity, and humor, or more negative characteristics of depression and anxiety. These analyses involved bipolar I subjects only and must be extended to other bipolar spectrum diagnoses, unaffected relatives, and individuals at risk. These results suggest that temperament and personality measures access latent traits associated with important clinical features of bipolar disorder. By translating clinical variables into quantitative traits, we may identify subgroups of bipolar patients with distinct clinical profiles, thereby facilitating both individual treatment strategies and genetic analyses. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Mammographic features of calcifications in DCIS: correlation with oestrogen receptor and human epidermal growth factor receptor 2 status

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Min Sun; Moon, Woo Kyung; Chang, Jung Min; Cho, Nariya [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Park, So Yeon; Won, Jae-Kyung; Jeon, Yoon-Kyung; Park, In Ae [Seoul National University College of Medicine, Department of Pathology, Seoul (Korea, Republic of); Moon, Hyeong-Gon; Han, Wonshik [Seoul National University College of Medicine, Department of Surgery, Seoul (Korea, Republic of)

    2013-08-15

    This study investigated the correlation of oestrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) status with the probability of malignancy (POM) of mammographic calcifications in ductal carcinoma in situ (DCIS). A total of 101 women (age range, 27-83 years) with pure DCIS that presented as mammographic calcifications were included. Three radiologists independently reviewed mammograms according to the BI-RADS lexicon and provided 100-point POM scores and a BI-RADS category. ER, HER2 and breast cancer subtypes were determined using immunohistochemistry (IHC) and fluorescence in situ hybridisation. Pairwise correlations between POM and IHC biomarker scores were calculated, and mammographic features were compared between breast cancer subtypes. HER2 level positively correlated with the POM score (P < 0.0001) and BI-RADS category (P < 0.0001), and ER level inversely correlated with the POM score (P < 0.013) and BI-RADS category (P < 0.010). Fine linear branching (P = 0.004) and segmental (P = 0.014) calcifications were significantly associated with HER2-positive cancers, and clustered calcifications were more frequently observed in ER-positive cancers (P = 0.014). HER2 status in DCIS correlated positively with the POM of mammographic calcifications, as determined by radiologists on the basis of the BI-RADS lexicon. (orig.)

  18. Sleep disorders in children with cerebral palsy and its correlation with sleep disturbance in primary caregivers and other associated factors

    Directory of Open Access Journals (Sweden)

    Dheeraj Adiga

    2014-01-01

    Full Text Available Aims: To observe prevalence of sleep disturbance (SD in cerebral palsy (CP children in a specific age-group and its correlation with SD in primary caregivers and other associated factors. Materials and Methods: This was a prospective cross-sectional study. SD assessed using Sleep Disturbance Scale for Children (SDSC in CP children and Pittsburgh Sleep Quality Index (PSQI in caregivers. Fifty cases of clinically diagnosed CP [27 females, mean age: 107.9 ΁ 29.5 months (range: 78-180 months] fulfilling criteria were included. Results: Eighteen (36% children had pathological sleep total score (TS and Disorders of Initiating and Maintaining Sleep (DIMS was the commonest SD (n = 25, 50%. All primary caregivers were mothers. Twenty-five (50% mothers had SD on PSQI scale. DIMS, Disorders of Excessive Somnolence (DES, and TS had significant correlation with PSQI (P < 0.05. Disorders of Arousal (DA and TS had significant correlation with seizures (P < 0.05 in CP children. Bed-sharing had significant correlation with SD in caregivers (P < 0.001 but not with CP children. No significant correlation was observed between SD in CP and gross motor function (Gross Motor Function Classification System, use of orthoses, and dental caries. Interpretation: Children with CP have underreported significant SD, which negatively impacts caregiver′s sleep also. Seizure disorders and medications contribute significantly to SD.

  19. Attitudinal barriers to participation in oncology clinical trials: factor analysis and correlates of barriers.

    Science.gov (United States)

    Manne, S; Kashy, D; Albrecht, T; Wong, Y-N; Lederman Flamm, A; Benson, A B; Miller, S M; Fleisher, Linda; Buzaglo, J; Roach, N; Katz, M; Ross, E; Collins, M; Poole, D; Raivitch, S; Miller, D M; Kinzy, T G; Liu, T; Meropol, N J

    2015-01-01

    Patient participation in cancer clinical trials is low. Little is known about attitudinal barriers to participation, particularly among patients who may be offered a trial during an imminent initial oncology consult. The aims of the present study were to confirm the presence of proposed subscales of a recently developed cancer clinical trial attitudinal barriers measure, describe the most common cancer clinical trials attitudinal barriers, and evaluate socio-demographic, medical and financial factors associated with attitudinal barriers. A total of 1256 patients completed a survey assessing demographic factors, perceived financial burden, prior trial participation and attitudinal barriers to clinical trials participation. Results of a factor analysis did not confirm the presence of the proposed four attitudinal barriers subscale/factors. Rather, a single factor represented the best fit to the data. The most highly-rated barriers were fear of side-effects, worry about health insurance and efficacy concerns. Results suggested that less educated patients, patients with non-metastatic disease, patients with no previous oncology clinical trial participation, and patients reporting greater perceived financial burden from cancer care were associated with higher barriers. These patients may need extra attention in terms of decisional support. Overall, patients with fewer personal resources (education, financial issues) report more attitudinal barriers and should be targeted for additional decisional support. © 2014 John Wiley & Sons Ltd.

  20. Gender differences in coronary artery disease: correlational study on dietary pattern and known cardiovascular risk factors.

    Science.gov (United States)

    Najafi, Mahdi; Sheikhvatan, Mehrdad

    2013-12-01

    The relationship between diet and cardiovascular risk factors in men and women with Coronary Artery Disease (CAD) has been the subject of recent studies. We studied a group of Iranian CAD patients to analyze any relationship between diet and CAD risk factors based on gender. In this study, 461 consecutive patients were assessed before their planned isolated coronary artery bypass graft surgery. They were interviewed to obtain the quantity and components of nutrients and micronutrients based on a validated food frequency questionnaire. Diet scores were calculated in each dietary group and the total score was reported as the Mediterranean Diet Quality Index (Med-DQI). Physical activity was assessed using International Physical Activity Questionnaire (IPAQ). Functional class, EuroSCORE and the frequency of the known risk factors in the men and women were recorded as well. The women were more likely than the men to present with obesity, diabetes mellitus, hypercholesterolemia, and hypertension (all Ps low in both sexes. MedDQI score was different between men and women with hypertension (P = 0.018) and obesity (P = 0.048). Modifiable classical risk factors for CAD, except for smoking, were more prevalent in women and were associated with their diet. Therefore, women probably need to maintain low calorie intake while improving physical activity and dietary patterns to decrease the frequency and severity of modifiable cardiac risk factors.

  1. Noise and vibration in friction systems

    CERN Document Server

    Sergienko, Vladimir P

    2015-01-01

    The book analyzes the basic problems of oscillation processes and theoretical aspects of noise and vibration in friction systems. It presents generalized information available in literature data and results of the authors in vibroacoustics of friction joints, including car brakes and transmissions. The authors consider the main approaches to abatement of noise and vibration in non-stationary friction processes. Special attention is paid to materials science aspects, in particular to advanced composite materials used to improve the vibroacoustic characteristics of tribopairs The book is intended for researchers and technicians, students and post-graduates specializing in mechanical engineering, maintenance of machines and transport means, production certification, problems of friction and vibroacoustics.

  2. Effect of grafted oligopeptides on friction.

    Science.gov (United States)

    Iarikov, Dmitri D; Ducker, William A

    2013-05-14

    Frictional and normal forces in aqueous solution at 25 °C were measured between a glass particle and oligopeptide films grafted from a glass plate. Homopeptide molecules consisting of 11 monomers of either glutamine, leucine, glutamic acid, lysine, or phenylalanine and one heteropolymer were each "grafted from" an oxidized silicon wafer using microwave-assisted solid-phase peptide synthesis. The peptide films were characterized using X-ray photoelectron spectroscopy and secondary ion mass spectrometry. Frictional force measurements showed that the oligopeptides increased the magnitude of friction compared to that on a bare hydrophilic silicon wafer but that the friction was a strong function of the nature of the monomer unit. Overall we find that the friction is lower for more hydrophilic films. For example, the most hydrophobic monomer, leucine, exhibited the highest friction whereas the hydrophilic monomer, polyglutamic acid, exhibited the lowest friction at zero load. When the two surfaces had opposite charges, there was a strong attraction, adhesion, and high friction between the surfaces. Friction for all polymers was lower in phosphate-buffered saline than in pure water, which was attributed to lubrication via hydrated salt ions.

  3. Friction & Wear Under Very High Electromagnetic Stress

    National Research Council Canada - National Science Library

    Cowan, Richard S; Danyluk, Steven; Moon, Francis; Ford, J. C; Brenner, Donald W

    2004-01-01

    This document summarizes initial progress toward advancing the fundamental understanding of the friction, wear and mechanics of interfaces subjected to extreme electromagnetic stress, high relative...

  4. Brain structure correlates of urban upbringing, an environmental risk factor for schizophrenia.

    Science.gov (United States)

    Haddad, Leila; Schäfer, Axel; Streit, Fabian; Lederbogen, Florian; Grimm, Oliver; Wüst, Stefan; Deuschle, Michael; Kirsch, Peter; Tost, Heike; Meyer-Lindenberg, Andreas

    2015-01-01

    Urban upbringing has consistently been associated with schizophrenia, but which specific environmental exposures are reflected by this epidemiological observation and how they impact the developing brain to increase risk is largely unknown. On the basis of prior observations of abnormal functional brain processing of social stress in urban-born humans and preclinical evidence for enduring structural brain effects of early social stress, we investigated a possible morphological correlate of urban upbringing in human brain. In a sample of 110 healthy subjects studied with voxel-based morphometry, we detected a strong inverse correlation between early-life urbanicity and gray matter (GM) volume in the right dorsolateral prefrontal cortex (DLPFC, Brodmann area 9). Furthermore, we detected a negative correlation of early-life urbanicity and GM volumes in the perigenual anterior cingulate cortex (pACC) in men only. Previous work has linked volume reductions in the DLPFC to the exposure to psychosocial stress, including stressful experiences in early life. Besides, anatomical and functional alterations of this region have been identified in schizophrenic patients and high-risk populations. Previous data linking functional hyperactivation of pACC during social stress to urban upbringing suggest that the present interaction effect in brain structure might contribute to an increased risk for schizophrenia in males brought up in cities. Taken together, our results suggest a neural mechanism by which early-life urbanicity could impact brain architecture to increase the risk for schizophrenia. © The Author 2014. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  5. New Approach of Frictional Behaviour for Modelling of High Speed Machining

    Science.gov (United States)

    Watremez, M.; Dubar, L.; Brocail, J.

    2011-05-01

    Numerical approaches to high-speed machining are necessary to increase productivity and to optimise the tool wear and the residual stresses. In order to apply such approaches, rheological behaviour of the antagonists and friction model of interfaces have to be correctly determined. The existing numerical approaches that are used with the current friction models do not generate good correlations of the process variables, such as the cutting forces or the tool-chip contact length. Recent studies [4-6] show the influence of friction model on the numerical results. This paper proposes a new approach for characterizing friction behaviour at the tool-chip interface in the zone near the cutting edge. The study is led with AISI 1045 steel and an uncoated carbide tool. An experimental device is designed to simulate the friction behaviour at the tool-chip interface. During this upsetting-sliding test, an indenter rubs in a specimen with a constant speed, generating a residual friction track. Thermo-mechanical parameters of machining process are firstly considered as the characteristics contact conditions to be reproduced on the testing stand. The contact pressure and the interfacial temperature are assessed with the finite element modelling of high-speed machining. The contactor penetration and the specimen temperature are the parameters to be determined in order to perform tests in concordance with the characteristic contact conditions. The ratio between the tangential and the normal force is defined as a friction index. Contact pressure and friction coefficient are determined from the test's numerical model and an iterative method is used to determine a Coulomb's coefficient by minimizing differences between the experimental and the numerical efforts. Several tests are then performed to provide experimental data and these data are used to define the friction coefficient versus to the contact pressure, the sliding velocity and the interfacial temperature by a new

  6. Correlation of primary tumor FDG uptake with clinicopathologic prognostic factors in invasive ductal carcinoma of the breast

    Energy Technology Data Exchange (ETDEWEB)

    Jo, I; Kim, Sung Hoon; Kim, Hae Won; Kang, Sung Hee [Keimyung University, School of Medicine, Daegu (Korea, Republic of); Zeon, Seok Kil [Dept. of Nuclear Medicine, Bundang Jesaeng General Hospital, Sungnam (Korea, Republic of); Kim, Su Jin [Dept. of Anesthesiology and Pain Medicine, Dongguk University, School of Medicine, Gyeongju (Korea, Republic of)

    2015-03-15

    The purpose of this study was to investigate the correlation of primary tumor FDG uptake to clinicopathological prognostic factors in invasive ductal carcinoma of the breast. We retrospectively reviewed 136 of 215 female patients with pathologically proven invasive ductal breast cancer from January 2008 to December 2011 who underwent F-18 FDG PET/CT for initial staging and follow-up after curative treatment with analysis of estrogen receptor (ER), progesterone receptor (PR) and human epithelial growth factor receptor 2 (HER2). The maximum standardized uptake value (SUV{sub max}) of the primary breast tumor was measured and compared with hormonal receptor and HER2 overexpression status. The high SUV{sub max} of primary breast tumors is significantly correlated with the clinicopathological factors: tumor size, histologic grade, TNM stage, negativity of ER, negativity of PR, HER2 overexpression and triple negativity. The recurrent group with non-triple negative cancer had a higher SUV{sub max} compared with the non-recurrent group, though no significant difference in FDG uptake was noted between the recurrence and non-recurrent groups in subjects with triple-negative cancer. Lymph node involvement was the independent risk factor for cancer recurrence in the multivariate analysis. In conclusion, high FDG uptake in primary breast tumors is significantly correlated with clinicopathological factors, such as tumor size, histologic grade, TNM stage, negativity of the hormonal receptor, HER2 overexpression and triple negativity. Therefore, FDG PET/CT is a helpful prognostic tool to direct the further management of patients with breast cancer.

  7. Correlation of CRP, Fasting Serum Triglycerides and Obesity as Cardiovascular Risk Factors

    International Nuclear Information System (INIS)

    Firdous, S.

    2014-01-01

    Objective: To determine the correlation of C-reactive protein (CRP) with fasting triglycerides (TG) among pre-obese and obese patients without established diagnosis of coronary artery disease (CAD). Study Design: A comparative cross-sectional study. Place and Duration of Study: Mayo Hospital, Lahore, from January to June 2010. Methodology: Patients with BMI > 23 kg/m2 aged between 18 - 65 years were inducted and above variables were studied. Patients with signs of fluid retention, collagen vascular disease, CAD, patients on corticosteroids, immunomodulators or lipid lowering medications and febrile patients were not recruited. Body mass index was also determined. Independent sample t-test was applied to see the mean difference of age, CRP level and triglycerides level in relation to gender. Chisquare test was used to see the association between qualitative variables. ANOVA was applied to see CRP and fasting serum TG level in relation to BMI categories. Pearson correlation and simple linear regression was applied to see the dependency of CRP and triglycerides with BMI. P-value A = 0.05 was taken as significant. Results: Raised CRP was major finding among all groups of BMI. Most of obese and pre-obese patients were young and middle aged and belonged to pre-obese group followed by class-1 and class-2 obesity. CRP level increased with body mass index. No such trend was observed for triglycerides. There was an intermediate positive correlation between CRP and BMI and triglycerides and BMI showed a weak negative correlation. If BMI increases by 1 unit on the average, CRP rises by 0.239 times and this unit rise was significant. Whereas 1 unit rise increase in triglycerides on the average cause CRP to decrease -0.006 times but this value was insignificant. Conclusion: Raised CRP and high fasting TG were major findings in all age groups especially among young and middle aged people. Obesity, hypertriglyceridemia and raised CRP are interrelated suggesting that obesity is not

  8. Characterization of friction and wear behavior of friction modifiers used in wheel-rail contacts

    NARCIS (Netherlands)

    Oomen, M. A.; Bosman, R.; Lugt, P. M.

    2017-01-01

    Reliable traction between wheel and rail is an important issue in the railway industry. To reduce variations in the coefficient of friction, so-called “friction modifiers” (carrier with particles) are used. Twin-disk tests were done with three commercial friction modifiers, based on different

  9. A Physics-Based Rock Friction Constitutive Law: Steady State Friction

    Science.gov (United States)

    Aharonov, Einat; Scholz, Christopher H.

    2018-02-01

    Experiments measuring friction over a wide range of sliding velocities find that the value of the friction coefficient varies widely: friction is high and behaves according to the rate and state constitutive law during slow sliding, yet markedly weakens as the sliding velocity approaches seismic slip speeds. We introduce a physics-based theory to explain this behavior. Using conventional microphysics of creep, we calculate the velocity and temperature dependence of contact stresses during sliding, including the thermal effects of shear heating. Contacts are assumed to reach a coupled thermal and mechanical steady state, and friction is calculated for steady sliding. Results from theory provide good quantitative agreement with reported experimental results for quartz and granite friction over 11 orders of magnitude in velocity. The new model elucidates the physics of friction and predicts the connection between friction laws to independently determined material parameters. It predicts four frictional regimes as function of slip rate: at slow velocity friction is either velocity strengthening or weakening, depending on material parameters, and follows the rate and state friction law. Differences between surface and volume activation energies are the main control on velocity dependence. At intermediate velocity, for some material parameters, a distinct velocity strengthening regime emerges. At fast sliding, shear heating produces thermal softening of friction. At the fastest sliding, melting causes further weakening. This theory, with its four frictional regimes, fits well previously published experimental results under low temperature and normal stress.

  10. Correlation between Novel Potential Indoor Risk Factors and Frequency of Doctor's Visit for Respiratory Problem in Taiwan's Tropical Environment

    Directory of Open Access Journals (Sweden)

    Yu-Hao Wang

    2018-01-01

    Full Text Available Background: With a global rising trend in prevalence of allergic diseases, more attention has been paid to investigation of environmental risk factors. Many risk factors have so far been identified. However, novel risk factors specific to Taiwanese environment and lifestyle were still relatively unknown. Objective: To investigate the potential effects of a number of little-known indoor risk factors on the frequency of doctor's visit for respiratory problems in context of Taiwanese environment and lifestyle. Methods: A cross-sectional, population-based study was performed on a 861 participants around Kaohsiung area, Taiwan. Survey investigation was employed to assess the household environment and the frequency of doctor's visit for respiratory problems. Results: Participants who performed “daily cleaning” was shown to have a significantly (p=0.007 higher mean number of doctor's visits in comparison to those who did not. Similar observation was made for participants who periodically took out beddings (p=0.042. Age had a significant positive correlation (linear regression β 0.089 with frequency of respiratory problems. Conclusion: The habit of daily cleaning was implicated as a potential indoor risk factor due to the unique nature of Taiwanese cleaning habit and close contact with cleaning supplies, which could serve as chemical irritants. Bedding takeout was predicted to be an indicator of chronic allergies rather than an actual risk factor. However, both were controversial in their role as potential indoor risk factor, and required further examination.

  11. The Rate of Physicochemical Incompatibilities, Administration Errors. Factors Correlating with Nurses' Errors.

    Science.gov (United States)

    Fahimi, Fanak; Sefidani Forough, Aida; Taghikhani, Sepideh; Saliminejad, Leila

    2015-01-01

    Medication errors are commonly encountered in hospital setting. Intravenous medications pose particular risks because of their greater complexity and the multiple steps required in their preparation, administration and monitoring. We aimed to determine the rate of errors during the preparation and administration phase of intravenous medications and the correlation of these errors with the demographics of nurses involved in the process. One hundred patients who were receiving IV medications were monitored by a trained pharmacist. The researcher accompanied the nurses during the preparation and administration process of IV medications. Collected data were compared with the acceptable guidelines. A checklist was filled for each IV medication. Demographic data of the nurses were collected as well. A total of 454 IV medications were recorded. Inappropriate administration rate constituted a large proportion of errors in our study (35.3%). No significant or life threatening drug interaction was recorded during the study. Evaluating the impact of the nurses' demographic characteristics on the incidence of medication errors showed that there is a direct correlation between nurses' employment status and the rate of medication errors, while other characteristics did not show a significant impact on the rate of administration errors. Administration errors were significantly higher in temporary 1-year contract group than other groups (p-value < 0.0001). Study results show that there should be more vigilance on administration rate of IV medications to prevent negative consequences especially by pharmacists. Optimizing the working conditions of nurses may play a crucial role.

  12. Factors affecting job satisfaction and their correlation with educational standards among dental assistants.

    Science.gov (United States)

    Al Jazairy, Yousra H; Halawany, Hassan Suliman; Hussainan, Nawaf Al; Maflehi, Nassr Al; Abraham, Nimmi Biju; Jacob, Vimal

    2014-01-01

    A disparity exists in the educational qualifications of dental assistants working in various public and private institutions in Riyadh, Saudi Arabia. The aim of this study was to assess the influence of professional and personal characteristics on job satisfaction among dental assistants. A cross-sectional survey was performed among dental assistants using a 24-item self-administered questionnaire. Multinomial logistic regression was used to assess the relationship between overall job satisfaction and other variables. The overall response rate was 72.1%. Factor analysis suggested that five underlying factors were related to job satisfaction. The mean score for overall job satisfaction was 3.86 (satisfied) out of 5. Among the work environment factors, the highest mean score, 4.26 (satisfied), was obtained for quality of service, and the lowest mean score, 2.78 (neutral), was obtained for the perception of income. The income and general prospects of the profession was significantly associated with overall job satisfaction. This study suggests that for dental assistants, professional and personal life, quality of service, perception of income and prestige and self-respect are important factors for job satisfaction. Despite differences in professional formation standards, in general, the study participants were considerably satisfied with their jobs.

  13. Trefoil factor peptide 3 is positively correlated with the viscoelastic properties of the cervical mucus plug

    DEFF Research Database (Denmark)

    Bastholm, Sara Kjær; Samson, Mie Hesselund; Becher, Naja

    2017-01-01

    The viscoelastic properties of the cervical mucus plug are considered essential for the occlusion of the cervical canal and thereby for protection against ascending infections during pregnancy. Factors controlling this property are virtually unknown. This study explores a possible role of trefoil...

  14. Factors correlated with developing caries during orthodontic treatment: Changes in saliva and behavioral risks

    Directory of Open Access Journals (Sweden)

    Edith Lara-Carrillo

    2012-09-01

    Conclusion: The multiple caries-related factors examined in this study changed during orthodontic treatment, but many of these stayed within normal values. Saliva is an important protector of oral mucosal tissues and teeth, and its constant role is supported even in adverse conditions, such as the presence of orthodontic appliances in the mouth.

  15. Factors Influencing Clinical Correlates of Chronic Traumatic Encephalopathy (CTE): A Review

    Science.gov (United States)

    Asken, Breton M.; Sullan, Molly J.; Snyder, Aliyah R.; Houck, Zachary M.; Bryant, Vaughn E.; Hizel, Loren P.; McLaren, Molly E.; Dede, Duane E.; Jaffee, Michael S.; DeKosky, Steven T.; Bauer, Russell M.

    2017-01-01

    Chronic traumatic encephalopathy (CTE) is a neuropathologically defined disease reportedly linked to a history of repetitive brain trauma. As such, retired collision sport athletes are likely at heightened risk for developing CTE. Researchers have described distinct pathological features of CTE as well a wide range of clinical symptom presentations, recently termed traumatic encephalopathy syndrome (TES). These clinical symptoms are highly variable, non-specific to individuals described as having CTE pathology in case reports, and are often associated with many other factors. This review describes the cognitive, emotional, and behavioral changes associated with 1) developmental and demographic factors, 2) neurodevelopmental disorders, 3) normal aging, 4) adjusting to retirement, 5) drug and alcohol abuse, 6) surgeries and anesthesia, and 7) sleep difficulties, as well as the relationship between these factors and risk for developing dementia-related neurodegenerative disease. We discuss why some professional athletes may be particularly susceptible to many of these effects and the importance of choosing appropriate controls groups when designing research protocols. We conclude that these factors should be considered as modifiers predominantly of the clinical outcomes associated with repetitive brain trauma within a broader biopsychosocial framework when interpreting and attributing symptom development, though also note potential effects on neuropathological outcomes. Importantly, this could have significant treatment implications for improving quality of life. PMID:27561662

  16. Correlations between the Five Factor Model of Personality and Problem Behavior in Children

    Science.gov (United States)

    Masood, Ambrin Faraz

    2009-01-01

    The validity of the Five Factor Model of personality traits has been mainly assessed with adults and late adolescents. Research has shown that adolescents are able to give reliable self-reports regarding their personality dispositions, but only a few studies have explored self-ratings in children younger than 12 years. Consistent patterns of…

  17. Prevalence of Internet Addiction and Correlations with Family Factors among South Korean Adolescents

    Science.gov (United States)

    Park, Soo Kyung; Kim, Jae Yop; Cho, Choon Bum

    2008-01-01

    This study investigated the prevalence of Internet addiction among South Korean adolescents and explored family factors associated with such addiction. The study participants were middle and high school students residing in Seoul. One-tenth (10.7%) of the 903 adolescents surveyed scored at least 70 on the Internet Addiction Scale. These youths…

  18. The influence of anxiety and personality factors on comfort and reachability space a correlational study

    NARCIS (Netherlands)

    Iachini, Tina; Ruggiero, Gennaro; Ruotolo, Francesco; Schiano di Cola, Armando; Senese, Vincenzo Paolo

    Although the effects of several personality factors on interpersonal space (i.e. social space within personal comfort area) are well documented, it is not clear whether they also extend to peripersonal space (i.e. reaching space). Indeed, no study has directly compared these spaces in relation to

  19. Clinical Correlates of Hachinski Ischemic Score and Vascular Factors in Cognitive Function of Elderly

    Directory of Open Access Journals (Sweden)

    Youn Ho Kim

    2014-01-01

    Full Text Available The aim of this study is to investigate the relationship between Hachinski ischemic score (HIS and vascular factors as well as between HIS and the cognitive function in elderly community. Demographic characteristics, such as sex, age, education, history of drinking and smoking, family history of dementia and stroke, diabetes mellitus, hypertension, hyperlipidemia, cardiovascular disease, stroke, and dementia, were surveyed. Neurological examination was administered to every subject and HIS was checked by a neurologist. From a total of 392 participants aged 65 and over in a rural community, 348 completed the survey and were finally enrolled. Among the vascular factors, history of hypertension (P=0.008, history of stroke (P<0.001, family history of dementia (P=0.01, and history of cardiac diseases (P=0.012 showed a significant relationship with HIS. In the cognitive function tests, both Korean version of the Mini-Mental State Examination and the Clinical Dementia Rating (Global and Sum of Boxes had a significant relationship with HIS. Our study suggested HIS may have an association with some vascular factors and cognitive scales in community dwelling elderly. In this study, the HIS seemed to contribute to the evaluation of the quantity of vascular factors and to the prediction of status of cognitive function.

  20. Gender Differences in Coronary Artery Disease: Correlational Study on Dietary Pattern and Known Cardiovascular Risk Factors

    Directory of Open Access Journals (Sweden)

    Mahdi Najafi

    2013-12-01

    Full Text Available Background: The relationship between diet and cardiovascular risk factors in men and women with Coronary Artery Disease (CAD has been the subject of recent studies. We studied a group of Iranian CAD patients to analyze any relationship between diet and CAD risk factors based on gender. Methods: In this study, 461 consecutive patients were assessed before their planned isolated coronary artery bypass graft surgery. They were interviewed to obtain the quantity and components of nutrients and micronutrients based on a validated food frequency questionnaire. Diet scores were calculated in each dietary group and the total score was reported as the Mediterranean Diet Quality Index (Med-DQI. Physical activity was assessed using International Physical Activity Questionnaire (IPAQ. Functional class, EuroSCORE and the frequency of the known risk factors in the men and women were recorded as well. Results: The women were more likely than the men to present with obesity, diabetes mellitus, hypercholesterolemia, and hypertension (all Ps < 0.001. Also, the women had higher functional class and mean of EuroSCORE (P < 0.001 and P = 0.03. Only six women (5.7% reported to have regular physical activity. In addition, Women’s energy intake was more likely to be supplied through fat. Cereals, fruit, and vegetable consumption in both genders was within the safe recommended range, while olive and fish consumption was low in both sexes. MedDQI score was different between men and women with hypertension (P = 0.018 and obesity (P = 0.048. Conclusions: Modifiable classical risk factors for CAD, except for smoking, were more prevalent in women and were associated with their diet. Therefore, women probably need to maintain low calorie intake while improving physical activity and dietary patterns to decrease the frequency and severity of modifiable cardiac risk factors.

  1. Assessment of Blood Flow in Hepatocellular Carcinoma: Correlations of Computed Tomography Perfusion Imaging and Circulating Angiogenic Factors

    Directory of Open Access Journals (Sweden)

    Chen-Pin Chou

    2013-08-01

    Full Text Available Hepatocellular carcinoma (HCC is a highly vascular tumor through the process of angiogenesis. To evaluate more non-invasive techniques for assessment of blood flow (BF in HCC, this study examined the relationships between BF of HCC measured by computer tomography (CT perfusion imaging and four circulating angiogenic factors in HCC patients. Interleukin 6 (IL-6, interleukin 8 (IL-8, vascular endothelial growth factor (VEGF, and platelet derived growth factor (PDGF in plasma were measured using Bio-Plex multiplex immunoassay in 21 HCC patients and eight healthy controls. Circulating IL-6, IL-8 and VEGF showed higher concentrations in HCC patients than in controls (p < 0.05, and predicted HCC occurrence better than chance (p < 0.01. Twenty-one patients with HCC received 21-phase liver imaging using a 64-slice CT. Total BF, arterial BF, portal BF, arterial fraction (arterial BF/total BF of the HCC and surrounding liver parenchyma, and HCC-parenchyma ratio were measured using a dual-vessel model. After analyzing the correlations between BF in HCC and four circulating angiogenic factors, we found that the HCC-parenchyma ratio of arterial BF showed a significantly positive correlation with the level of circulating IL-8 (p < 0.05. This circulating biomarker, IL-8, provides a non-invasive tool for assessment of BF in HCC.

  2. Higher HOMA-IR index and correlated factors of insulin resistance in patients with IgA nephropathy.

    Science.gov (United States)

    Yang, Yue; Wei, Ri-Bao; Wang, Yuan-da; Zhang, Xue-Guang; Rong, Na; Tang, Li; Chen, Xiang-Mei

    2012-11-01

    To investigate the index of homeostasis model of insulin resistance (HOMA-IR) in IgA nephropathy (IgAN) patients, and to explore the possible correlated factors contributing to insulin resistance (IR) within these patients. There were 255 IgAN patients and 45 membranous nephropathy (MN) patients in our database. We identified 89 IgAN subjects and 21 MN subjects without diabetes and undergoing glucocorticoid therapy for at least 6 months. Data regarding physical examination, blood chemistry and renal pathology were collected from 89 IgAN subjects and 21 MN subjects. Then 62 IgAN patients and 19 MN patients with chronic kidney disease (CKD) Stage 1 - 2 were selected for the comparison of HOMA-IR index, 89 IgAN patients were selected for multiple regression analysis to test for correlated factors of HOMA-IR index with IgAN patients. Comparison between IgAN and MN show that HOMA-IR index was significantly higher in IgAN patients with CKD Stage 1 - 2. After logarithmic transformation with urine protein (UPr), Ln(UPr) (b = 0.186, p = 0.008), eGFR (b = -0.005, p = 0.014), > 50% of glomeruli with mesangial hypercellularity (b = 0.285, p = 0.027) and body mass index (BMI) (b = 0.039, p = 0.008) were correlated factors of HOMA-IR index in the multiple regression analysis. IgAN patients had higher HOMA-IR index compared with MN in the stages of CKD 1 - 2. For IgAN patients, more UPr, lower eGFR, > 50% of glomeruli with mesangial hypercellularity and higher BMI were correlated with IR.

  3. Finger pad friction and tactile perception of laser treated, stamped and cold rolled micro-structured stainless steel sheet surfaces

    NARCIS (Netherlands)

    Zhang, Sheng; Zeng, X.; Matthews, D.T.A.; Igartua, A.; Rodriguez Vidal, E.; Contreras Fortes, J.; Van Der Heide, E.

    2017-01-01

    Tactile perception is a complex system, which depends on frictional interactions between skin and counter-body. The contact mechanics of tactile friction is governed by many factors such as the state and properties of skin and counter-body. In order to discover the connection between perception and

  4. Finger pad friction and tactile perception of laser treated, stamped and cold rolled micro-structured stainless steel sheet surfaces

    NARCIS (Netherlands)

    Zhang, S.; Zeng, X.; Matthews, D. T A; Igartua, A.; Rodriguez-Vidal, E.; Contreras Fortes, J.; van der Heide, E.

    2017-01-01

    Tactile perception is a complex system, which depends on frictional interactions between skin and counter-body. The contact mechanics of tactile friction is governed by many factors such as the state and properties of skin and counter-body. In order to discover the connection between perception

  5. Microstructural evolution and properties of friction stir welded aluminium alloy AA2219

    International Nuclear Information System (INIS)

    Gupta, R. K.; Biju, S.; Ghosh, B. R.; Sinha, P. P.

    2007-01-01

    Low weld strength of fusion welded joints of aluminium alloy AA2219 is a concern in fabrication of pressure vessels and is attributable to the presence of weld defects, as well as various metallurgical factors. Friction stir welding (FSW), being a solid state joining process has obvious advantages over fusion welding. Results of preliminary FSW experiments conducted on 10 mm thick plate using a particular tool configuration are presented here. Microscopic studies show the presence of very fine equiaxed recrystallised grain at the weld nugget and a flow pattern of grains due to heavy deformation in defect-free weld coupons. Mechanical properties are correlated with the microstructure and process variables. Fractographic analysis complements the observations of optical microscopy and mechanical properties

  6. [Correlation between morphogical factor of lateral plateau fracture and meniscus injury].

    Science.gov (United States)

    Bai, L; Zhou, W; Zhang, W T; Huang, W; You, T; Chen, P; Zhang, H L

    2016-04-18

    To analyze morphological character of lateral tibial plateau fracture fragment, and its correlation to the presence of a meniscus injury in tibial plateau fractures. A total of 79 consecutive patients of the simple lateral tibial plateau fractures from July 2011 to July 2015 were included in this study, with 65 males and 14 females with an average age of (34.3±7.2) years and 22-61 years. According to Schatzker classification, 21 cases were of Type I, 41 cases Type II, and 17 cases Type III. The characteristics of lateral tibial plateau fractures were evaluated by plain X-ray and magnetic resonance imaging (MRI). The type and severity of meniscus injury were diagnosed by MRI scan. Three-dimensional measurements of the lateral fragment width (LFW), the lateral plateau depression (LPD), the coronal angulation of lateral fragment (CALF), and tibial plateau widening (TPW) were measured with Picture Archiving and Communication Systems(PACS) software. The patients with and without meniscus injuries were divided into different groups and analyzed respectively. Comparison of the above measurements between the two groups was analyzed by independent t test. In all the 79 lateral tibial plateau fracture patients, 26 cases (32.9%) of meniscus injuries were detected by MRI. Among all the meniscus injury cases, 3 were of Schatzker I, 16 Schatzker II, and 7 Schatzker III. In meniscus intact group, the average LFW was (22.0±2.8) mm while in meniscus injury group it was (21.3± 3.3) mm (t=-1.008, P=0.317).The average LPD of non meniscus injury group was (5.4±2.8) mm, while in meniscus injury group was (8.7±2.8) mm (t=4.98, P=0.001). The average CALF of the two groups were 9.1°±6.1°and 10.6°± 7.1°, and there was no significant difference between the two groups (t=0.38, P=0.831). The average TPW was (3.0± 1.1) mm, and (4.8±1.7) mm of the two groups. There were significant differences between the two groups (t=5.216, P=0.001). There was no obvious correlation between the

  7. Probing weld quality monitoring in friction stir welding through characterization of signals by fractal theory

    International Nuclear Information System (INIS)

    Das, Bipul; Bag, Swarup; Pal, Sukhomay

    2017-01-01

    Providing solutions towards the improvisation of welding technologies is the recent trend in the Friction stir welding (FSW) process. We present a monitoring approach for ultimate tensile strength of the friction stir welded joints based on information extracted from process signals through implementing fractal theory. Higuchi and Katz algorithms were executed on current and tool rotational speed signals acquired during friction stir welding to estimate fractal dimensions. Estimated fractal dimensions when correlated with the ultimate tensile strength of the joints deliver an increasing trend with the increase in joint strength. It is observed that dynamicity of the system strengthens the weld joint, i.e., the greater the fractal dimension, the better will be the quality of the weld. Characterization of signals by fractal theory indicates that the single-valued indicator can be an alternative for effective monitoring of the friction stir welding process.

  8. Probing weld quality monitoring in friction stir welding through characterization of signals by fractal theory

    Energy Technology Data Exchange (ETDEWEB)

    Das, Bipul; Bag, Swarup; Pal, Sukhomay [Indian Institute of Technology Guwahati, Assam (India)

    2017-05-15

    Providing solutions towards the improvisation of welding technologies is the recent trend in the Friction stir welding (FSW) process. We present a monitoring approach for ultimate tensile strength of the friction stir welded joints based on information extracted from process signals through implementing fractal theory. Higuchi and Katz algorithms were executed on current and tool rotational speed signals acquired during friction stir welding to estimate fractal dimensions. Estimated fractal dimensions when correlated with the ultimate tensile strength of the joints deliver an increasing trend with the increase in joint strength. It is observed that dynamicity of the system strengthens the weld joint, i.e., the greater the fractal dimension, the better will be the quality of the weld. Characterization of signals by fractal theory indicates that the single-valued indicator can be an alternative for effective monitoring of the friction stir welding process.

  9. Bias Factor and Therapeutic Window Correlate to Predict Safer Opioid Analgesics.

    Science.gov (United States)

    Schmid, Cullen L; Kennedy, Nicole M; Ross, Nicolette C; Lovell, Kimberly M; Yue, Zhizhou; Morgenweck, Jenny; Cameron, Michael D; Bannister, Thomas D; Bohn, Laura M

    2017-11-16

    Biased agonism has been proposed as a means to separate desirable and adverse drug responses downstream of G protein-coupled receptor (GPCR) targets. Herein, we describe structural features of a series of mu-opioid-receptor (MOR)-selective agonists that preferentially activate receptors to couple to G proteins or to recruit βarrestin proteins. By comparing relative bias for MOR-mediated signaling in each pathway, we demonstrate a strong correlation between the respiratory suppression/antinociception therapeutic window in a series of compounds spanning a wide range of signaling bias. We find that βarrestin-biased compounds, such as fentanyl, are more likely to induce respiratory suppression at weak analgesic doses, while G protein signaling bias broadens the therapeutic window, allowing for antinociception in the absence of respiratory suppression. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Flow Dominance and Factorization of Transverse Momentum Correlations in Pb-Pb Collisions at the LHC

    Czech Academy of Sciences Publication Activity Database

    Adam, J.; Adamová, Dagmar; Bielčík, J.; Bielčíková, Jana; Brož, M.; Contreras, J. G.; Ferencei, Jozef; Hladký, Jan; Horák, D.; Křížek, Filip; Kučera, Vít; Kushpil, Svetlana; Lavička, R.; Mareš, Jiří A.; Petráček, V.; Pospíšil, Jan; Šumbera, Michal; Vaňát, Tomáš; Závada, Petr

    2017-01-01

    Roč. 118, č. 16 (2017), č. článku 162302. ISSN 0031-9007 R&D Projects: GA MŠk(CZ) LG15052 Institutional support: RVO:68378271 ; RVO:61389005 Keywords : ALICE collaboration * heavy ion collisions * two particle transverse momentum Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders; BF - Elementary Particles and High Energy Physics (FZU-D) OBOR OECD: Nuclear physics; Particles and field physics (FZU-D) Impact factor: 8.462, year: 2016

  11. Prevalence of Dyspepsia and its Correlation with Demographic Factors and Lifestyle in Shiraz, Southern Iran

    OpenAIRE

    Khademolhosseini, F; Mehrabani, D; Zare, N; Salehi, M; Heydari, ST; Beheshti, M; Saberi-Firoozi, M

    2010-01-01

    BACKGROUND Dyspepsia is a common disorder that can present many clinical dilemmas in patient management. Although not life-threatening, the symptoms are long-lasting, interfere with daily activities and have a significant impact upon quality of life. The aim of this study was to determine prevalence of dyspepsia and its relationship with demographic and socioeconomic factors, and lifestyle in an apparently healthy population in Shiraz, southern Iran. METHODS In a population-based study, 1978 ...

  12. Factors correlated with traffic accidents as a basis for evaluating Advanced Driver Assistance Systems.

    Science.gov (United States)

    Staubach, Maria

    2009-09-01

    This study aims to identify factors which influence and cause errors in traffic accidents and to use these as a basis for information to guide the application and design of driver assistance systems. A total of 474 accidents were examined in depth for this study by means of a psychological survey, data from accident reports, and technical reconstruction information. An error analysis was subsequently carried out, taking into account the driver, environment, and vehicle sub-systems. Results showed that all accidents were influenced by errors as a consequence of distraction and reduced activity. For crossroad accidents, there were further errors resulting from sight obstruction, masked stimuli, focus errors, and law infringements. Lane departure crashes were additionally caused by errors as a result of masked stimuli, law infringements, expectation errors as well as objective and action slips, while same direction accidents occurred additionally because of focus errors, expectation errors, and objective and action slips. Most accidents were influenced by multiple factors. There is a safety potential for Advanced Driver Assistance Systems (ADAS), which support the driver in information assimilation and help to avoid distraction and reduced activity. The design of the ADAS is dependent on the specific influencing factors of the accident type.

  13. Dimensional approach to delusions in psychotic depression in the elderly: factor structure and clinical correlates.

    Science.gov (United States)

    Gournellis, Rossetos; Oulis, Panagiotis; Michalopoulou, Panagiota; Kaparoudaki, Adamantia; Dimitrakopoulos, Christos; Lykouras, Lefteris

    2009-04-01

    The present study attempted to investigate the clinically important broader dimensions of clinical characteristics of delusions, through multivariate analysis, in a pure sample of elderly unipolar delusional depressives as well as to test their external validity against a set of demographic, anamnestic and psychopathological validators. Fifty inpatients suffering from psychotic major depression (PMD) in the context of major depressive disorder, 60 years old or older, were assessed on the basis of SCID IV, HRSD, MMSE and by three-point ordinal scales of 12 clinical, intrinsic or relational characteristics of delusions tested for their inter-rater reliability. Principal Component Analysis resulted in the extraction of five factors, jointly accounting for 69.7% of the total variance. The five factors were interpreted as representing the dimensions of delusional strength, acute upsetting, delusional organization, incomprehensibility and incitation to actions. Most of the factors were differentially associated with patients' demographic, anamnestic and clinical variables. Our results overlap in part with those of another similar study in delusional depressives of all age-ranges, differing, however, in respects possibly attributable to peculiarities of elderly depressives. Overall, the findings of the present study contribute to the further elucidation of major clinical dimensions of delusions in PMD in the elderly and the testing of their external validity. (c) 2008 John Wiley & Sons, Ltd.

  14. Prevalence of dyspepsia and its correlation with demographic factors and lifestyle in shiraz, southern iran.

    Science.gov (United States)

    Khademolhosseini, F; Mehrabani, D; Zare, N; Salehi, M; Heydari, St; Beheshti, M; Saberi-Firoozi, M

    2010-01-01

    BACKGROUND Dyspepsia is a common disorder that can present many clinical dilemmas in patient management. Although not life-threatening, the symptoms are long-lasting, interfere with daily activities and have a significant impact upon quality of life. The aim of this study was to determine prevalence of dyspepsia and its relationship with demographic and socioeconomic factors, and lifestyle in an apparently healthy population in Shiraz, southern Iran. METHODS In a population-based study, 1978 subjects aged 35 years or older were interviewed from April to September 2004. A questionnaire consisting of demographic factors, lifestyle data and gastrointestinal symptoms was completed for each participant. The validity and reliability of the questionnaire were determined. RESULTS The prevalence of dyspepsia was 29.9%. The dyspeptic patients were classified as having ulcer-like (27.9%), dysmotility-like (26.2%) or unspecified dyspepsia (45.9%). The prevalence was higher in females, water-pipe smokers, NSAIDs users, and in those with psychological distress, recurrent headache, anxiety, nightmares and past history of gastrointestinal disease. Dyspepsia had an inverse relationship with consumption of pickles, fruits and vegetables, and with duration of meal ingestion. Subjects with dyspepsia symptoms were more likely to restrict their diet, take herbal medicine, use over-the-counter drugs, consult with physicians and consume medication advised by their friends. CONCLUSION This study reveals that dyspepsia has a high prevalence in Shiraz, southern Iran and is associated with several demographic factors, lifestyle and health-seeking behavior.

  15. 18F-fluoroethylcholine uptake in arterial vessel walls and cardiovascular risk factors. Correlation in a PET-CT study

    International Nuclear Information System (INIS)

    Foerster, Stefan; Rominger, A.; Cumming, P.; Bartenstein, P.; Hacker, M.; Saam, T.; Nikolaou, K.; Reiser, M.F.; Wolpers, S.; Univ. Muenchen

    2010-01-01

    Fluorine-labelled choline derivatives were recently suggested as agents for visualizing vulnerable atherosclerotic plaques. We therefore aimed to evaluate the association between 18 F-fluorethylcholine (FEC) uptake in the wall of large arteries, where calcification was also measured, with the presence of cardiovascular risk factors and occurrence of prior cardiovascular events. Detailed clinical information, including common cardiovascular risk factors, was obtained retrospectively in 60 prostate cancer patients examined with whole-body FEC PET-CT. In each patient, we calculated the mean blood pool-corrected SUV, as well as the mean target-to-background ratio (TBR), in addition to the sum of calcified plaques (CP sum ) from six major vessels: ascending and descending aorta, aortic arch, abdominal aorta, and both iliac arteries. As reported previously, the CP sum correlated significantly with cardiovascular risk factors, in contrast to mean SUV or TBR scores, which did not show any significance with the presence of cardiovascular risk factors. There was no correlation between CP sum , mean TBR or SUV, nor was there any significant association of CP sum , mean TBR or SUV with the prior occurrence of cardio- or cerebrovascular events. Contrary to a recent report, we found in our rather large cohort of elderly prostate cancer patients no significant association between FEC uptake in large vessels and atherosclerotic plaque burden, or the presence of cardiovascular risk factors. In line with prior reports on structural changes in vessels, increased calcified atherosclerotic plaque burden was strongly associated with the occurrence of common cardiovascular risk factors. (orig.)

  16. Correlation of Vitreous Vascular Endothelial Growth Factor and Uric Acid Concentration Using Optical Coherence Tomography in Diabetic Macular Edema

    Directory of Open Access Journals (Sweden)

    Libuse Krizova

    2015-01-01

    Full Text Available Purpose. We investigated two factors linked to diabetic macular edema (DME, vitreous and serum levels of vascular endothelial growth factor (VEGF and uric acid (UA in patients with DME, and compared the results with changes in optical coherence tomography (OCT and visual acuity (VA. Methods. A prospective study of 29 eyes, 16 cystoid DME and nonproliferative diabetic retinopathy (DR and 13 nondiabetic controls. Biochemical analysis of vitreous and serum samples was performed and OCT scans were graded according to central retinal thickness (CRT, cube volume (CV, cube average thickness (CAT, and serous retinal detachment (SRD. Results. In DME group, intravitreal concentrations of VEGF (p<0.001, UA (p=0.038, and total protein (p<0.001 were significantly higher than in control group. In DME subjects, intravitreal UA correlated significantly with intravitreal VEGF (ƍ = 0.559, p=0.03 but not with total vitreous protein and serum UA. Increased intravitreal VEGF in DME group correlated with increase in CV (ƍ = 0.515/p=0.041. None of the OCT parameters correlated with the VA. Conclusions. The results suggest that the CV might be assessor of anti-VEGF therapy efficacy. Second, apart from VEGF, the role of UA in the pathogenesis and progression of DR should be considered.

  17. Quantum Friction in Different Regimes

    Science.gov (United States)

    Klatt, Juliane; Buhmann, Stefan

    2015-03-01

    Quantum friction is the velocity-dependent force between two polarizable objects in relative motion, resulting from field-fluctuation mediated transfer of energy and momentum between them. Due to its short-ranged nature it has proven difficult to observe experimentally. Theoretical attempts to determine the precise velocity-dependence of the quantum drag experienced by a polarizable atom moving parallel to a surface arrive at contradicting results. Scheel and Barton predict a force linear in relative velocity v - the former using the quantum regression theorem and the latter employing time-dependent perturbation theory. Intravaia, however, predicts a v3 power-law starting from a non-equilibrium fluctuation-dissipation theorem. In order to learn where exactly the above approaches part, we set out to perform all three calculations within one and the same framework: macroscopic QED. In addition, we include contributions to quantum friction from Doppler shift and Röntgen interaction, which play a role for perpendicular motion and retarded distances, respectively, and consider non-stationary states of atom and field. DFG Emmy-Noether Program.

  18. Mathematical models of viscous friction

    CERN Document Server

    Buttà, Paolo; Marchioro, Carlo

    2015-01-01

    In this monograph we present a review of a number of recent results on the motion of a classical body immersed in an infinitely extended medium and subjected to the action of an external force. We investigate this topic in the framework of mathematical physics by focusing mainly on the class of purely Hamiltonian systems, for which very few results are available. We discuss two cases: when the medium is a gas and when it is a fluid. In the first case, the aim is to obtain microscopic models of viscous friction. In the second, we seek to underline some non-trivial features of the motion. Far from giving a general survey on the subject, which is very rich and complex from both a phenomenological and theoretical point of view, we focus on some fairly simple models that can be studied rigorously, thus providing a first step towards a mathematical description of viscous friction. In some cases, we restrict ourselves to studying the problem at a heuristic level, or we present the main ideas, discussing only some as...

  19. Kozai Cycles and Tidal Friction

    Energy Technology Data Exchange (ETDEWEB)

    L, K; P.P., E

    2009-07-17

    Several studies in the last three years indicate that close binaries, i.e. those with periods of {approx}< 3 d, are very commonly found to have a third body in attendance. We argue that this proves that the third body is necessary in order to make the inner period so short, and further argue that the only reasonable explanation is that the third body causes shrinkage of the inner period, from perhaps a week or more to the current short period, by means of the combination of Kozai cycles and tidal friction (KCTF). In addition, once KCTF has produced a rather close binary, magnetic braking also combined with tidal friction (MBTF) can decrease the inner orbit further, to the formation of a contact binary or even a merged single star. Some of the products of KCTF that have been suggested, either by others or by us, are W UMa binaries, Blue Stragglers, X-ray active BY Dra stars, and short-period Algols. We also argue that some components of wide binaries are actually merged remnants of former close inner pairs. This may include such objects as rapidly rotating dwarfs (AB Dor, BO Mic) and some (but not all) Be stars.

  20. Low-friction nanojoint prototype

    Science.gov (United States)

    Vlassov, Sergei; Oras, Sven; Antsov, Mikk; Butikova, Jelena; Lõhmus, Rünno; Polyakov, Boris

    2018-05-01

    High surface energy of individual nanostructures leads to high adhesion and static friction that can completely hinder the operation of nanoscale systems with movable parts. For instance, silver or gold nanowires cannot be moved on silicon substrate without plastic deformation. In this paper, we experimentally demonstrate an operational prototype of a low-friction nanojoint. The movable part of the prototype is made either from a gold or silver nano-pin produced by laser-induced partial melting of silver and gold nanowires resulting in the formation of rounded bulbs on their ends. The nano-pin is then manipulated into the inverted pyramid (i-pyramids) specially etched in a Si wafer. Due to the small contact area, the nano-pin can be repeatedly tilted inside an i-pyramid as a rigid object without noticeable deformation. At the same time in the absence of external force the nanojoint is stable and preserves its position and tilt angle. Experiments are performed inside a scanning electron microscope and are supported by finite element method simulations.

  1. Correlation between hedgehog (hh) protein family and brain-derived neurotrophic factor (bdnf) in autism spectrum disorder (asd)

    International Nuclear Information System (INIS)

    Halepoto, D.M.; Bashir, S.

    2015-01-01

    To determine the correlation of Sonic Hedgehog (SHH), Indian Hedgehog (IHH), and Brain-Derived Neurotrophic Factor (BDNF) in children with Autism Spectrum Disorder (ASD). Study Design: An observational, comparative study. Place and Duration of Study: Autism Research and Treatment Center, Al-Amodi Autism Research Chair, Department of Physiology, Faculty of Medicine, King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia, from October 2011 to May 2012. Methodology: Serum levels of SHH, IHH and BDNF were determined in recently diagnosed autistic patients and age matched healthy children (n=25), using the Enzyme-Linked Immunosorbent Assay (ELISA). Childhood Autism Rating Scale (CARS) was used for the assessment of autistic severity. Spearman correlation co-efficient-r was determined. Results: The serum levels of IHH and SHH were significantly higher in autistic subjects than those of control subjects. There was significant correlation between age and IHH (r = 0.176, p = 0.03), BDNF and severe IHH (r = 0.1763, p = 0.003), and severe BDNF and severe SHH (r = 0.143, p < 0.001). However, there were no significant relationships among the serum levels of SHH, IHH and BDNF and the CARS score, age or gender. Conclusion: The findings support a correlation between SHH, IHH and BDNF in autistic children, suggesting their pathological role in autism. (author)

  2. Serum level of brain-derived neurotrophic factor in fibromyalgia syndrome correlates with depression but not anxiety.

    Science.gov (United States)

    Nugraha, Boya; Korallus, Christoph; Gutenbrunner, Christoph

    2013-02-01

    Brain-derived neurotrophic factor (BDNF) has been known to play a role in fibromyalgia syndrome (FMS) patients. Depression and anxiety are quite common additional symptoms in FMS. However the role of BDNF in these symptoms still needs to be elucidated. Although BDNF has been shown to be relevant in major depression, however studies could not show such differences between FMS patients with and without major depression. As mood-related symptom occurs frequently and differs in its intensity in FMS patients, BDNF level should be measured in subgroup regarding depression and anxiety scale. Therefore the aim of this study was to evaluate the correlation of BDNF in serum of FMS with intensity of depression and anxiety. Additionally, interleukin (IL)-6 was measured. This study showed that serum level of BDNF was age-dependent in HCs. FMS patients had higher level of serum BDNF as compared to HC. Additionally, serum level of BDNF showed correlation with depression, but not with anxiety. Serum level of BDNF increased with depression score in FMS. However, serum level of IL-6 was not correlated with both depression and anxiety scores. Taken together, BDNF is involved in the pathophysiology of FMS. Additionally, it seems to be correlated with intensity of depressive symptoms in FMS. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Nonlinear internal friction, chaos, fractal and musical instruments

    International Nuclear Information System (INIS)

    Sun, Z.Q.; Lung, C.W.

    1995-08-01

    Nonlinear and structure sensitive internal friction phenomena in materials are used for characterizing musical instruments. It may be one of the most important factors influencing timbre of instruments. As a nonlinear dissipated system, chaos and fractals are fundamental peculiarities of sound spectra. It is shown that the concept of multi range fractals can be used to decompose the frequency spectra of melody. New approaches are suggested to improve the fabrication, property characterization and physical understanding of instruments. (author). 18 refs, 4 figs

  4. Behaviour of Frictional Joints in Steel Arch Yielding Supports

    Czech Academy of Sciences Publication Activity Database

    Horyl, P.; Šňupárek, Richard; Maršálek, P.

    2014-01-01

    Roč. 59, č. 3 (2014), s. 723-734 ISSN 0860-7001 R&D Projects: GA MŠk ED2.1.00/03.0082; GA MŠk ED1.1.00/02.0070 Institutional support: RVO:68145535 Keywords : steel arch yielding support * friction al joints * bolt connection * slip support * fem Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 0.608, year: 2013

  5. Autocalibration of Electrodiffusion Friction Probes in Microdispersion Liquids

    Czech Academy of Sciences Publication Activity Database

    Wein, Ondřej

    2010-01-01

    Roč. 53, 9-10 (2010), s. 1874-1881 ISSN 0017-9310 R&D Projects: GA ČR GA104/08/0428; GA ČR GA104/09/0972 Institutional research plan: CEZ:AV0Z40720504 Keywords : electrodiffusion friction probes * voltage-step transient * edge effects in microdispersion liquids Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.898, year: 2010

  6. Blade couple connected by damping element with dry friction contacts

    Czech Academy of Sciences Publication Activity Database

    Pešek, Luděk; Půst, Ladislav

    2014-01-01

    Roč. 52, č. 3 (2014), s. 815-826 ISSN 1429-2955 R&D Projects: GA ČR GA101/09/1166 Institutional support: RVO:61388998 Keywords : dry friction * three masses system * damping of vibrations * irregular vibrations Subject RIV: BI - Acoustics Impact factor: 0.636, year: 2014 http://www.ptmts.org.pl/article.xsl?vol=52&no=3&page=815

  7. Erectile dysfunction and correlated factors in Brazilian men aged 18-40 years.

    Science.gov (United States)

    Martins, Fernando Gonini; Abdo, Carmita Helena Najjar

    2010-06-01

    Few population-based studies in erectile dysfunction (ED) included subjects less than 40 years old and analyzed the several factors and consequences potentially associated with this condition. Evaluation of the prevalence of erectile dysfunction (ED) and associated factors in a sample of Brazilian men aged 18 to 40 years old. Cross-sectional study in which subjects were contacted in public places of 18 major Brazilian cities and interviewed using an anonymous questionnaire. Survey data were submitted to chi-squared, student's t-test and logistic regression analyses. The data were collected by means of a self-administered questionnaire with 87 questions about sociodemographic variables, general health, habits and lifestyle-related factors, sexual behavior and sexual difficulties, including ED which was assessed by a single question. Prevalence of ED in 1,947 men was 35.0% (73.7% mild, 26.3% moderate/complete). Greater frequency of ED was seen in subjects that never had information about sex, experienced difficulties in the beginning of sexual life and have never masturbated. ED was associated to lower level of education, but not to race, sexual orientation, employment or marital status. Also, no association was found between ED and smoking, alcoholism, obesity, sedentary life, diabetes, hypertension, cardiovascular disease, hyperlipidemia, depression or anxiety. ED caused negative impact in men's self-esteem, interpersonal relationships, work and leisure activities, and in sexual life satisfaction. Less than 10% of men with ED had received medical treatment for this problem. Prevalence of ED in this young population was high, mostly of mild severity. Low education and psychosocial problems were associated to ED and, due probably to the sample subjects' young age, no association was found with organic problems. Measures in the fields of education and psychosocial difficulties prevention would have a positive impact in the control of erectile dysfunction in the young

  8. Correlation between psychological factors and the cerebellar volume of normal young adults

    Directory of Open Access Journals (Sweden)

    Chung Soon-Cheol

    2010-01-01

    Full Text Available Este estudio analiza la relación entre el volumen del cerebelo de adultos normales en la tercera década de la vida (20-29 años y varios factores psicológicos. El volumen del cerebelo de 118 sujetos (media de edad 23 ± 2,6 años, incluyendo 58 varones (media de edad 24 ± 2,8 años y 60 mujeres (media de edad, 21,9 ± 2,1 años, fue medido utilizando la imagen por resonancia magnética (IRM. Todos los participantes completaron los siguientes tests: Cuestionario de 90 Síntomas (SCL-90-R, Cuestionario de Personalidad de Tipo A, El cuestionario de Ansiedad Estado Korean YZ, El Cuestionario de 16 Factores de la Personalidad (16PF, y la Escala Autoadministrada de Depresión (EAD. Utilizando regresión linear, se analizó la relación entre el volumen del cerebelo y factores psicológicos. Sin considerar las diferencias entre géneros, en cuanto crecía la tendencia hacia la personalidad tipo A y se incrementaba el estado de ansiedad y la fuerza del superego, disminuía el volumen del cerebelo. Cuando se incrementaba la fuerza del ego, se incrementaba el volumen del cerebelo. Cuando se consideraban las diferencias de género, cuando incrementaba la ansiedad fóbica y ambición en varones, disminuía el volumen del cerebelo. En mujeres, cuando incrementaba la hostilidad, tensión y la ansiedad estado, disminuía el volumen del cerebelo.

  9. Alcohol consumption after the recognition of pregnancy and correlated factors among indigenous pregnant women in Taiwan.

    Science.gov (United States)

    Yen, Cheng-Fang; Yang, Mei-Sang; Lai, Chien-Yu; Chen, Cheng-Chih; Yeh, Yi-Chun; Wang, Peng-Wei

    2012-02-01

    To examine the rates and factors associated with alcohol consumption after the recognition of pregnancy among indigenous pregnant women, as well as the rates and factors associated with continuing alcohol consumption after the recognition of pregnancy among indigenous pregnant women who drank alcohol before the recognition of pregnancy in 10 hospitals in southern and eastern Taiwan. A total of 806 indigenous women who had just given birth in 10 hospitals in southern and eastern Taiwan were recruited. They were interviewed to collect their substance use information, demographic characteristics, psychological health status, history of physical abuse, and pregnancy history. The rates of alcohol consumption after the recognition of pregnancy in all indigenous pregnant women and the rates of continuing alcohol consumption after the recognition of pregnancy among those who drank alcohol before the recognition of pregnancy were calculated. The factors relating to alcohol consumption and continuing alcohol consumption after the recognition of pregnancy were examined using logistic regression analyses. The results of this study found that 26.6% of indigenous pregnant women drank alcohol at any stage after the recognition of pregnancy, and 52.5% of indigenous pregnant women who drank alcohol before the recognition of pregnancy persisted in drinking alcohol after the recognition of pregnancy. Multiple parities, smoking or chewing betel quid after the recognition of pregnancy, and a higher frequency of drinking alcohol before the recognition of pregnancy were significantly associated with alcohol consumption and continuing alcohol consumption after the recognition of pregnancy. Meanwhile, being single or divorced, and intimate partner violence after the recognition of pregnancy were significantly associated with alcohol consumption after the recognition of pregnancy. High prevalence rates of alcohol consumption and continuing alcohol consumption after the recognition of

  10. FRICTION MODELING OF Al-Mg ALLOY SHEETS BASED ON MULTIPLE REGRESSION ANALYSIS AND NEURAL NETWORKS

    Directory of Open Access Journals (Sweden)

    Hirpa G. Lemu

    2017-03-01

    Full Text Available This article reports a proposed approach to a frictional resistance description in sheet metal forming processes that enables determination of the friction coefficient value under a wide range of friction conditions without performing time-consuming experiments. The motivation for this proposal is the fact that there exists a considerable amount of factors affect the friction coefficient value and as a result building analytical friction model for specified process conditions is practically impossible. In this proposed approach, a mathematical model of friction behaviour is created using multiple regression analysis and artificial neural networks. The regression analysis was performed using a subroutine in MATLAB programming code and STATISTICA Neural Networks was utilized to build an artificial neural networks model. The effect of different training strategies on the quality of neural networks was studied. As input variables for regression model and training of radial basis function networks, generalized regression neural networks and multilayer networks the results of strip drawing friction test were utilized. Four kinds of Al-Mg alloy sheets were used as a test material.

  11. Single-crystal-silicon-based microinstrument to study friction and wear at MEMS sidewall interfaces

    International Nuclear Information System (INIS)

    Ansari, N; Ashurst, W R

    2012-01-01

    Since the advent of microelectromechanical systems (MEMS) technology, friction and wear are considered as key factors that determine the lifetime and reliability of MEMS devices that contain contacting interfaces. However, to date, our knowledge of the mechanisms that govern friction and wear in MEMS is insufficient. Therefore, systematically investigating friction and wear at MEMS scale is critical for the commercial success of many potential MEMS devices. Specifically, since many emerging MEMS devices contain more sidewall interfaces, which are topographically and chemically different from in-plane interfaces, studying the friction and wear characteristics of MEMS sidewall surfaces is important. The microinstruments that have been used to date to investigate the friction and wear characteristics of MEMS sidewall surfaces possess several limitations induced either by their design or the structural film used to fabricate them. Therefore, in this paper, we report on a single-crystal-silicon-based microinstrument to study the frictional and wear behavior of MEMS sidewalls, which not only addresses some of the limitations of other microinstruments but is also easy to fabricate. The design, modeling and fabrication of the microinstrument are described in this paper. Additionally, the coefficients of static and dynamic friction of octadecyltrichlorosilane-coated sidewall surfaces as well as sidewall surfaces with only native oxide on them are also reported in this paper. (paper)

  12. Estimation of the friction coefficient between wheel and rail surface using traction motor behaviour

    International Nuclear Information System (INIS)

    Zhao, Y; Liang, B; Iwnicki, S

    2012-01-01

    The friction coefficient between a railway wheel and rail surface is a crucial factor in maintaining high acceleration and braking performance of railway vehicles thus monitoring this friction coefficient is important. Restricted by the difficulty in directly measuring the friction coefficient, the creep force or creepage, indirect methods using state observers are used more frequently. This paper presents an approach using a Kalman filter to estimate the creep force and creepage between the wheel and rail and then to identify the friction coefficient using the estimated creep force-creepage relationship. A mathematic model including an AC motor, wheel and roller is built to simulate the driving system. The parameters are based on a test rig at Manchester Metropolitan University. The Kalman filter is designed to estimate the friction coefficient based on the measurements of the simulation model. Series of residuals are calculated through the comparison between the estimated creep force and theoretical values of different friction coefficient. Root mean square values of the residuals are used in the friction coefficient identification.

  13. Gimbaled-shoulder friction stir welding tool

    Science.gov (United States)

    Carter, Robert W. (Inventor); Lawless, Kirby G. (Inventor)

    2010-01-01

    A gimbaled-shoulder friction stir welding tool includes a pin and first and second annular shoulders coupled to the pin. At least one of the annular shoulders is coupled to the pin for gimbaled motion with respect thereto as the tool is rotated by a friction stir welding apparatus.

  14. Advanced friction modeling in sheet metal forming

    NARCIS (Netherlands)

    Hol, J.; Cid Alfaro, M.V.; Meinders, Vincent T.; Huetink, Han

    2011-01-01

    The Coulomb friction model is frequently used for sheet metal forming simulations. This model incorporates a constant coefficient of friction and does not take the influence of important parameters such as contact pressure or deformation of the sheet material into account. This article presents a

  15. Friction tensor concept for textured surfaces

    Indian Academy of Sciences (India)

    This paper proposes the concept of a friction tensor analogous to the heat conduc- tion tensor in anisotropic media. This implies that there exists two principal friction coefficients μ1,2 analogous to the principal conductivities k1,2. For symmetrically textured surfaces the principal directions are orthogonal with atleast one ...

  16. Friction in textile thermoplastic composites forming

    NARCIS (Netherlands)

    Akkerman, Remko; ten Thije, R.H.W.; Sachs, Ulrich; de Rooij, Matthias B.; Binetruy, C.; Boussu, F.

    2010-01-01

    A previously developed mesoscopic friction model for glass/PP textile composite laminates during forming is evaluated for glass and carbon/PPS laminates, at higher temperatures and lower viscosities than before. Experiments were performed for tool/ply and ply/ply configurations in a new friction

  17. The role of friction in tow mechanics

    NARCIS (Netherlands)

    Cornelissen, Bo

    2013-01-01

    Friction plays and important role in the processing of fibrous materials: during production of tow materials, during textile manufacturing and during preforming operations for composite moulding processes. One of the poorly understood phenomena in these processes is the dynamic frictional behaviour

  18. Friction Coefficient Determination by Electrical Resistance Measurements

    Science.gov (United States)

    Tunyagi, A.; Kandrai, K.; Fülöp, Z.; Kapusi, Z.; Simon, A.

    2018-01-01

    A simple and low-cost, DIY-type, Arduino-driven experiment is presented for the study of friction and measurement of the friction coefficient, using a conductive rubber cord as a force sensor. It is proposed for high-school or college/university-level students. We strongly believe that it is worthwhile planning, designing and performing Arduino…

  19. Position-dependent friction in quantum mechanics

    International Nuclear Information System (INIS)

    Srokowski, T.

    1985-01-01

    The quantum description of motion of a particle subjected to position-dependent frictional forces is presented. The two cases are taken into account: a motion without external forces and in the harmonic oscillator field. As an example, a frictional barrier penetration is considered. 16 refs. (author)

  20. Device measures static friction of magnetic tape

    Science.gov (United States)

    Cole, P. T.

    1967-01-01

    Device measures the coefficient of static friction of magnetic tape over a range of temperatures and relative humidities. It uses a strain gage to measure the force of friction between a reference surface and the tape drawn at a constant velocity of approximately 0.0001 inch per second relative to the reference surface.

  1. Friction tensor concept for textured surfaces

    Indian Academy of Sciences (India)

    friction coefficients of Mg and Al-Mg alloy pins sliding over EN8 steel flats. The sliding angle was varied between 0 and 90 degrees and morphology of ... has explained friction based on energy dissipation mechanisms initiated in the early history of tribology by Rabinowicz (1951). Despite the spatio-temporal complexity in ...

  2. Factors influencing parenting efficacy of Asian immigrant, first-time mothers: A cross-sectional, correlational survey.

    Science.gov (United States)

    Roh, Eun Ha; Ahn, Jeong-Ah; Park, Somi; Song, Ju-Eun

    2017-12-01

    In this study, we determined the factors influencing parenting efficacy of Asian immigrant, first-time mothers. The research design was a cross-sectional, correlational study. The study included 125 first-time mothers who immigrated and married Korean men, and were living in Korea. Data were collected using translated questionnaires, and analyzed for descriptive statistics, Pearson correlation, and multiple regression analysis. The major finding was that the parenting efficacy of immigrant women was influenced by childcare support from their husbands, maternal identity, and original nationality. The findings suggest that customized programs be developed and used to enhance parenting efficacy for Asian immigrant, first-time mothers. In developing such programs, the advantages of maternal identity, social support from the husband, and women's cultural context should be considered. © 2017 John Wiley & Sons Australia, Ltd.

  3. Study on the Criteria for the Determination of the Road Load Correlation for Automobiles and an Analysis of Key Factors

    Directory of Open Access Journals (Sweden)

    Charyung Kim

    2016-07-01

    Full Text Available To determine the fuel economy and emissions of a vehicle using a chassis dynamometer, the load to which the vehicle is subjected when it actually runs on a road, or the road load specifications, must be simulated when the dynamometer is applied. The most commonly used method to measure road load specifications is coastdown testing. Currently, road load is measured and provided by the manufacturer of the vehicle. Verification of the accuracy of the manufacturer’s reported road load specifications by a third party may reveal that the specifications are inaccurate, possibly because of different testing locations, test drivers or test equipment. This study aims at identifying key factors that can affect a vehicle’s road load correlation by using experimental design and deriving criteria for determining the correlation based on the energy difference.

  4. PET-CT detection rate of primary breast cancer lesions. Correlation with the clinicopathological factors

    International Nuclear Information System (INIS)

    Ogawa, Tomoko; Tozaki, Mitsuhiro; Fukuma, Eisuke

    2008-01-01

    One hundred and forty lesions of primary breast cancer underwent positron emission tomography (PET)-CT between June 2006 and May 2007. The PET-CT detection rate of primary breast cancer lesions was 72.1%. The detection rate was 52.1% for invasive cancer ≤20 mm, 92.8% for invasive breast cancers >20 mm, and these results were significant. In the present study, no significant relationship was observed between tumor types, however, invasive lobular carcinoma showed a lower detection rate, 58.3%. The PET-CT results were not significantly affected by either estrogen and progesterone receptors or distant metastasis. A significant correlation regarding the detection rate of PET-CT was found with HER2 status, tumor grade, and axillary lymph node status. The detection rate was 100% for invasive cancer ≤20 mm when the interval between prior diagnostic Mammotome biopsies and PET-CT was less than 3 weeks, 18.8% for invasive cancer ≤20 mm when the interval was more than 3 weeks, and these results were significant. Mammotome biopsies may therefore affect the detection rate of PET-CT. Invasive cancers ≤20 mm showed a low detection rate, therefore, it is considered to be insufficient to use PET-CT for the detection of early breast cancer. (author)

  5. Trial manufacture of rotary friction tester and frictional force measurement of metals

    CERN Document Server

    Abe, T; Kanari, M; Tanzawa, S

    2002-01-01

    In the plasma confinement type fusion reactor, in-vessel structures such as a blanket module slide at the joints each other when plasma disruption occurs, and then frictional heat is generated there. Therefore, for the selection of material and the use as the design data, it is important to understand the frictional characteristics of metals and ceramic films in the vacuum. In the present study, we have manufactured a prototype of rotary friction tester and examined the performances of the tester. The frictional characteristics of metals in the room air was measured using the friction tester, and the results obtained are as follows. A drifting friction force for a constant time and a friction force during the idling were 98 mN and 225 mN, respectively. These values were sufficiently small as compared to pressing load (9.8 - 57.8 N) used in the friction test. In a friction force measurement of stainless steel, dynamic friction force obeyed Amontons' law which indicated that dynamic friction force is not depend...

  6. The Clinical Correlations of Helicobacter pylori Virulence Factors and Chronic Spontaneous Urticaria

    Directory of Open Access Journals (Sweden)

    Yi-Chun Chiu

    2013-01-01

    Full Text Available Background and Study Aims. The association between Helicobacter pylori (H. pylori and chronic spontaneous urticaria (CSU remains controversial. This study explored the role of H. pylori in CSU among different virulent genotypes patients. Patients and Methods. Patients infected by H. pylori were sorted into two groups as group A (with CSU and group B (without CSU. The tissue materials were taken via endoscopy for polymerase chain reaction study to determine virulence factors. After H. pylori eradication therapy, the eradication rate and response of urticaria were evaluated by using C13-UBT and a three-point scale (complete remission, partial remission, or no improvement. Results. The results were comparable between patients of groups A and B in terms of H. pylori infection rates and eradication rate. Longitudinal follow-up of 23.5 months showed complete remission of urticaria in 63.6% but no improvement in 36.4% of the patients after H. pylori eradication. H. pylori infected patients with different virulence factors such as cytotoxin-associated gene A, vacuolating cytotoxin gene A signal region and middle region have similar remission rates for CSU. Conclusions. Current study suggests that H. pylori may play a role in the development and disease course of CSU but may be irrelevant to different virulent genotypes.

  7. Quantitative Correlation of 7B04 Aluminum Alloys Pitting Corrosion Morphology Characteristics with Stress Concentration Factor

    Science.gov (United States)

    Liu, Zhiguo; Yan, Guangyao; Mu, Zhitao; Li, Xudong

    2018-01-01

    The accelerated pitting corrosion test of 7B04 aluminum alloy specimen was carried out according to the spectrum which simulated airport environment, and the corresponding pitting corrosion damage was obtained and was defined through three parameters A and B and C which respectively denoted the corrosion pit surface length and width and corrosion pit depth. The ratio between three parameters could determine the morphology characteristics of corrosion pits. On this basis the stress concentration factor of typical corrosion pit morphology under certain load conditions was quantitatively analyzed. The research shows that the corrosion pits gradually incline to be ellipse in surface and moderate in depth, and most value of B/A and C/A lies in 1 between 4 and few maximum exceeds 4; The stress concentration factor Kf of corrosion pits is obviously affected by the its morphology, the value of Kf increases with corrosion pits depth increasement under certain corrosion pits surface geometry. Also, the value of Kf decreases with surface width increasement under certain corrosion pits depth. The research conclusion can set theory basis for corrosion fatigue life analysis of aircraft aluminum alloy structure.

  8. A lack of correlation between brain-derived neurotrophic factor serum level and verbal memory performance in healthy Polish population

    Directory of Open Access Journals (Sweden)

    Monika eWilkosc

    2016-05-01

    Full Text Available Brain derived neurotrophic factor is considered to be connected with memory and learning through the processes of long term synaptic potentiation and synaptic plasticity. The aim of the study was to examine the relationship between precursor BDNF (proBNDF and mature BDNF (mBDNF serum levels and performance on Rey Auditory-Verbal Learning Test (RAVLT in 150 healthy volunteers. In addition, we have verified the relationships between serum concentration of both forms of BDNF and RAVLT with sociodemographic and lifestyle factors. We found no strong evidence for the correlation of proBDNF and mBDNF serum levels with performance on RAVLT in healthy Polish population in early and middle adulthood. We observed the mBDNF serum concentration to be higher in women compared with men. Moreover, we revealed higher mBDNF level to be connected with lower Body Mass Index (BMI. In turn, the results of RAVLT correlated with sociodemographic and lifestyle factors, such as: age, education, gender, BMI and smoking.

  9. Tumor necrosis factor-α levels correlate with postoperative pain severity in lumbar disc hernia patients: opposite clinical effects between tumor necrosis factor receptor 1 and 2.

    Science.gov (United States)

    Andrade, Pablo; Visser-Vandewalle, Veerle; Philippens, Marjan; Daemen, Marc A; Steinbusch, Harry W M; Buurman, Wim A; Hoogland, Govert

    2011-11-01

    Lumbar disc hernia (LDH) is a leading cause of chronic pain in adults. The underlying pathology of chronic pain after discectomy remains unclear. Chronic local inflammation is considered to underlie painful symptomatology. In this context, we investigated tumor necrosis factor (TNF)-α, TNF receptor 1 (TNFR1), and TNF receptor 2 (TNFR2) expression at the time of surgery in LDH patients and correlated it with the severity of postoperative pain. We analyzed protein and mRNA levels from muscle, ligamentum flavum (LF), annulus fibrosus (AF), and nucleus pulposus (NP) in LDH patients and scoliosis patients (SP), who served as controls. Pain assessment with the visual analogue scale (VAS) was performed 1 day before surgery and 6 weeks and 12 months postoperatively. TNF-α protein levels were detected in AF, LF, and NP in all LDH patients, but not in SP. TNF-α mRNA was significantly greater in LDH patients than in SP; ie, 5-fold in AF, 3-fold in NP, and 2-fold in LF. For NP, TNF-α protein levels correlated with VAS scores (r=0.54 at 6-week and r=0.65 at 12-month follow-up). Also, TNFR1 protein levels in NP positively correlated with VAS scores (r=0.75 at 6-week and r=0.80 at 12-month follow-up). However, TNFR2 protein levels in AF negatively correlated with VAS scores (r=-0.60 at 6 weeks and r=-0.60 at 12 months follow-up). These data indicate that TNF-α levels could determine the clinical outcome in LDH patients after discectomy. Moreover, the opposite correlation of TNF receptors with pain sensation suggests that an unbalanced expression plays a role in the generation of pain. Copyright © 2011 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  10. The Internalized Homophobia Scale for Vietnamese Sexual Minority Women: Conceptualization, Factor Structure, Reliability, and Associations With Hypothesized Correlates.

    Science.gov (United States)

    Nguyen, Trang Quynh; Poteat, Tonia; Bandeen-Roche, Karen; German, Danielle; Nguyen, Yen Hai; Vu, Loan Kieu-Chau; Nguyen, Nam Thi-Thu; Knowlton, Amy R

    2016-08-01

    We developed the first Vietnamese Internalized Homophobia (IH) scale for use with Vietnamese sexual minority women (SMW). Drawing from existing IH scales in the international literature and based on prior qualitative research about SMW in the Viet Nam context, the scale covers two domains: self-stigma (negative attitudes toward oneself as a sexual minority person) and sexual prejudice (negative attitudes toward homosexuality/same-sex relations in general). Scale items, including items borrowed from existing scales and items based on local expressions, were reviewed and confirmed by members of the target population. Quantitative evaluation used data from an anonymous web-based survey of Vietnamese SMW, including those who identified as lesbian (n = 1187), or as bisexual (n = 641) and those who were unsure about their sexual identity (n = 353). The scale was found to consist of two highly correlated factors reflecting self-stigma (not normal/wholesome and self-reproach and wishing away same-sex sexuality) and one factor reflecting sexual prejudice, and to have excellent internal consistency. Construct validity was evidenced by subscale associations with a wide range of hypothesized correlates, including perceived sexual stigma, outness, social support, connection to other SMW, relationship quality, psychological well-being, anticipation of heterosexual marriage, and endorsement of same-sex marriage legalization. Self-stigma was more strongly associated with psychosocial correlates, and sexual prejudice was more associated with endorsement of legal same-sex marriage. The variations in these associations across the hypothesized correlates and across sexual identity groups were consistent with the minority stress model and the IH literature, and exhibited context-specific features, which are discussed.

  11. Novel friction law for the static friction force based on local precursor slipping.

    Science.gov (United States)

    Katano, Yu; Nakano, Ken; Otsuki, Michio; Matsukawa, Hiroshi

    2014-09-10

    The sliding of a solid object on a solid substrate requires a shear force that is larger than the maximum static friction force. It is commonly believed that the maximum static friction force is proportional to the loading force and does not depend on the apparent contact area. The ratio of the maximum static friction force to the loading force is called the static friction coefficient µM, which is considered to be a constant. Here, we conduct experiments demonstrating that the static friction force of a slider on a substrate follows a novel friction law under certain conditions. The magnitude of µM decreases as the loading force increases or as the apparent contact area decreases. This behavior is caused by the slip of local precursors before the onset of bulk sliding and is consistent with recent theory. The results of this study will develop novel methods for static friction control.

  12. Longitudinal Study of Bad Dreams in Preschool-Aged Children: Prevalence, Demographic Correlates, Risk and Protective Factors

    Science.gov (United States)

    Simard, Valérie; Nielsen, Tore A.; Tremblay, Richard E.; Boivin, Michel; Montplaisir, Jacques Y.

    2008-01-01

    Study objectives: To (1) clarify the epidemiology of bad dreams in children and investigate risk and protective factors related to (2) the child's sleep, (3) parental sleep-enabling practices, and (4) the child's temperament. Design: Longitudinal with 6 time points from 5 months to 6 years. Setting: Subjects' homes. Participants: Representative sample of 987 children in the Province of Quebec. Interventions: None. Measurements and Results: Longitudinal logistic regression analysis models with primary endpoints of presence or absence of parent-rated bad dreams at 29 months, 41 months, 50 months, 5 years, and 6 years and predictor variables of demographic characteristics, parent ratings of child's sleep characteristics, parental sleep-enabling practices (e.g., cosleeping), and child's psychological characteristics at 5 and 17 months (anxiousness, temperament). Mothers' ratings indicated lower than expected prevalence of frequent bad dreams (1.3% to 3.9%). Demographic correlates of bad dreams were high family income, absence of siblings at 29 months, and a non-immigrant mother. The best predictor at 41 and 50 months was the presence of bad dreams the preceding year, whereas at 5 and 6 years, it was their earlier presence at 29 months. Early protective factors were parental practices favoring emotional nurturance after night awakenings (29 and 41 months); early risk factors were sleep-onset emotional nurturance (29 months), difficult temperament (5 months), and anxiousness (17 months). Conclusions: Bad dreams in preschoolers are less prevalent than thought but, when present, are trait-like in nature and associated with personality characteristics measured as early as 5 months. A stress-diathesis model may best account for the observed pattern of predictive factors. Citation: Simard V; Nielsen TA; Tremblay RE; Boivin M; Montplaisir JY. Longitudinal study of bad dreams in preschool-aged children: prevalence, demographic correlates, risk and protective factors. SLEEP 2008

  13. Frictional properties of jointed welded tuff

    International Nuclear Information System (INIS)

    Teufel, L.W.

    1981-07-01

    The results of the experiments on simulated joints in welded tuff from the Grouse Canyon Member of the Belted Range Tuff warrant the following conclusions: (1) The coefficient of friction of the joints is independent of normal stress at a given sliding velocity. (2) The coefficient of friction increases with both increasing time of stationary contact and decreasing sliding velocity. (3) Time and velocity dependence of friction is due to an increase in the real area of contact on the sliding surface, caused by asperity creep. (4) Joints in water-saturated tuff show a greater time and velocity dependence of friction than those in dehydrated tuff. (5) The enhanced time and velocity dependence of friction with water saturation is a result of increased creep at asperity contacts, which is in turn due to a reduction in the surface indentation hardness by hydrolytic weakening and/or stress corrosion cracking

  14. On the geometric phenomenology of static friction

    Science.gov (United States)

    Ghosh, Shankar; Merin, A. P.; Nitsure, Nitin

    2017-09-01

    In this note we introduce a hierarchy of phase spaces for static friction, which give a graphical way to systematically quantify the directional dependence in static friction via subregions of the phase spaces. We experimentally plot these subregions to obtain phenomenological descriptions for static friction in various examples where the macroscopic shape of the object affects the frictional response. The phase spaces have the universal property that for any experiment in which a given object is put on a substrate fashioned from a chosen material with a specified nature of contact, the frictional behaviour can be read off from a uniquely determined classifying map on the control space of the experiment which takes values in the appropriate phase space.

  15. On the geometric phenomenology of static friction.

    Science.gov (United States)

    Ghosh, Shankar; Merin, A P; Nitsure, Nitin

    2017-09-06

    In this note we introduce a hierarchy of phase spaces for static friction, which give a graphical way to systematically quantify the directional dependence in static friction via subregions of the phase spaces. We experimentally plot these subregions to obtain phenomenological descriptions for static friction in various examples where the macroscopic shape of the object affects the frictional response. The phase spaces have the universal property that for any experiment in which a given object is put on a substrate fashioned from a chosen material with a specified nature of contact, the frictional behaviour can be read off from a uniquely determined classifying map on the control space of the experiment which takes values in the appropriate phase space.

  16. Molecular profile of major growth factors in lumbar intervertebral disc herniation: Correlation with patient clinical and epidemiological characteristics.

    Science.gov (United States)

    Tsarouhas, Alexandros; Soufla, Giannoula; Tsarouhas, Konstantinos; Katonis, Pavlos; Pasku, Dritan; Vakis, Antonis; Tsatsakis, Aristides M; Spandidos, Demetrios A

    2017-04-01

    The involvement of growth factors (GFs) in the pathogenesis of lumbar intervertebral disc (ID) herniation and the spontaneous resorption of herniated ID fragments remains only partially elucidated. A simultaneous assessment of the transcript levels of numerous GFs and their association with clinical and epidemiological profiles of human ID herniation would provide valuable insight into the biology and clinical course of the disease. In the present study, we examined simultaneously the transcript levels of vascular endothelial growth factor (VEGF), transforming growth factor β1 (TGF‑β1), basic fibroblast growth factor 2 (bFGF2), platelet derived growth factor (PDGF) isoforms and receptors, epidermal growth factor (EGF) and insulin growth factor‑1 (IGF‑1) in herniated and control ID specimens and investigated their correlation with the clinicopathological profiles of patients suffering from symptomatic lumbar ID herniation. GF mRNA expression levels were determined by RT-qPCR in 63 surgical specimens from lumbar herniated discs and 10 control ID specimens. Multiple positive correlations were observed between the transcript levels of the GFs examined in the ID herniation group. VEGF mRNA expression was significantly increased in the protruding compared with the extruded discs. Intense and acute pain significantly upregulated the PDGF transcript levels. Significant negative correlations were observed between the patient body mass index and the transcript levels of VEGF and PDGF receptors. Our findings support the hypothesis of the involvement of GFs in the natural history of ID herniation. GFs synergistically act in herniated IDs. Increased VEGF expression possibly induces the neovascularization process in the earliest stages of ID herniation. PDGF‑C and ‑D play a role in the acute phase of radiculopathy in a metabolic response for tissue healing. A molecular effect, in addition to the biomechanical effect of obesity in the

  17. The impact of childhood bullying among HIV-positive men: psychosocial correlates and risk factors.

    Science.gov (United States)

    Kamen, Charles; Bergstrom, Jessica; Vorasarun, Chaniga; Mardini, Mona; Patrick, Rudy; Lee, Susanne; Lazar, Rachael; Koopman, Cheryl; Gore-Felton, Cheryl

    2013-04-01

    While some studies have examined the deleterious effects of childhood bullying on adults, no studies to date have focused on the effects of bullying on Persons Living with HIV (PLH), a particularly at-risk population. PLH experience higher rates of childhood and adulthood physical and sexual abuse than the population at large, and experience of childhood abuse appears to be predictive of sexual and other risk behaviors in this population. Thus it remains critical to examine rates of childhood bullying and correlates of bullying in adult PLH. A sample of 171 HIV-positive men over 18 years of age were recruited from the San Francisco Bay Area. All participants reported experiencing symptoms of traumatic stress. The participants were recruited as part of a larger study assessing a group intervention for individuals with HIV and symptoms of trauma. Self-report questionnaires were administered to assess participants' exposure to bullying in childhood and trauma symptoms in adulthood. Bullying was commonly reported by men in the current sample, with 91% of the sample endorsing having experienced some level of bullying before age 18. Having been bullied in childhood was significantly (ptrauma. Results of a hierarchical regression equation found that report of bullying in childhood predicted additional, unique variance in trauma symptoms in adulthood above and beyond the effect of exposure to other forms of trauma, resulting in a better-fitting model. The current study highlights the association between rate of childhood bullying and symptoms of trauma in adulthood, accounting for the effect of exposure to other forms of trauma. Given the impact of trauma symptoms on disease progression in PLH, exposure to bullying must be considered in any intervention aiming to reduce trauma symptoms or improve mental or physical health among HIV-positive populations. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. The Impact of Childhood Bullying among HIV-Positive Men: Psychosocial Correlates and Risk Factors

    Science.gov (United States)

    Kamen, Charles; Bergstrom, Jessica; Vorasarun, Chaniga; Mardini, Mona; Patrick, Rudy; Lee, Susanne; Lazar, Rachael; Koopman, Cheryl; Gore-Felton, Cheryl

    2012-01-01

    Objectives While some studies have examined the deleterious effects of childhood bullying on adults, no studies to date have focused on the effects of bullying on Persons Living with HIV (PLH), a particularly at-risk population. PLH experience higher rates of childhood and adulthood physical and sexual abuse than the population at large, and experience of childhood abuse appears to be predictive of sexual and other risk behaviors in this population. Thus it remains critical to examine rates of childhood bullying and correlates of bullying in adult PLH. Methods A sample of 171 HIV-positive men over 18 years of age were recruited from the San Francisco Bay Area. All participants reported experiencing symptoms of traumatic stress. The participants were recruited as part of a larger study assessing a group intervention for individuals with HIV and symptoms of trauma. Self-report questionnaires were administered to assess participants’ exposure to bullying in childhood and trauma symptoms in adulthood. Results Bullying was commonly reported by men in the current sample, with 91% of the sample endorsing having experienced some level of bullying before age 18. Having been bullied in childhood was significantly (p < .05) associated with methamphetamine use in adulthood, difficulties with mood, and with symptoms of trauma. Results of a hierarchical regression equation found that report of bullying in childhood predicted additional, unique variance in trauma symptoms in adulthood above and beyond the effect of exposure to other forms of trauma, resulting in a better-fitting model. Conclusions The current study highlights the association between rate of childhood bullying and symptoms of trauma in adulthood, accounting for the effect of exposure to other forms of trauma. Given the impact of trauma symptoms on disease progression in PLH, exposure to bullying must be considered in any intervention aiming to reduce trauma symptoms or improve mental or physical health among HIV

  19. Correlation Between Placental Matrix Metalloproteinase 9 and Tumor Necrosis Factor-α Protein Expression Throughout Gestation in Normal Human Pregnancy.

    Science.gov (United States)

    Basu, Jayasri; Agamasu, Enyonam; Bendek, Bolek; Salafia, Carolyn M; Mishra, Aruna; Lopez, Julia Vasquez; Kroes, Jessica; Dragich, Sharon Claire; Thakur, Ashley; Mikhail, Magdy

    2018-04-01

    Matrix metalloproteinases (MMPs), specifically MMP-9 plays a role in human placentation. The enzyme confers an invasive ability to cytotrophoblasts and degrades the endometrial matrix as the cells infiltrate the decidua to keep up with placental growth. Since tumor necrosis factor-α (TNF-α) can induce the synthesis of MMP-9, we investigated the patterns of changes in and correlation between placental villous MMP-9 and TNF-α expressions throughout normal human gestation. Placentas were obtained from 179 normal pregnant women who underwent elective abortion or term delivery. Chorionic villi isolated from placental samples were grouped as first, second, and third trimester (7 0/7 -13 0/7 , 13 1/7 -23 6/7 , and 37 0/7 -42 4/7 weeks, respectively). Chorionic villous TNF-α and MMP-9 proteins were assayed using enzyme immunoassay kits. There were significant differences in MMP-9 and TNF-α protein expressions among the trimester groups ( P = .001). The MMP-9 protein increased progressively with an increase in gestational age (GA), but TNF-α peaked in the second trimester. Within each trimester group, we searched for the effects of variation of GA in days on the 2 variables. A significant positive correlation between MMP-9 and GA was noted in the first trimester ( r = 0.364, P = .005). No other comparisons were significant. When GA was controlled for, partial correlation revealed a significant positive correlation between TNF-α and MMP-9 only in the second trimester ( r = 0.300, P = .018). We hypothesize that the TNF-α peak and the positive correlation between TNF-α and MMP-9 in the second trimester of normal human gestation could contribute toward a successful pregnancy outcome.

  20. Male Factors and socioeconomic indicators correlate with the risk of spontaneous abortion

    DEFF Research Database (Denmark)

    Olsen, Jørn; Basso, Olga; Christensen, Kaare

    1999-01-01

    No less than 10% of clinically recognised pregnancies end as spontaneous abortions and the recurrence risk is high. Due to lack of data and appropriate study design only little is known about preventable causes of miscarriage. The aim of this study was to estimate the effect of paternal...... and environmental factors by studying reproductive histories in population based cohorts. We based the study upon two cohorts. The 'abortion cohort' consisted of 55 259 women who had a hospitalised spontaneous abortion in Denmark between 1980 and 1992 and who had a subsequent non-terminated pregnancy. The 'birth...... the personal identification numbers and information stored in several population registers. Change of partner reduced the recurrence risk of spontaneous abortion substantially (OR = 0.59; 95 CI 0.52-0.67), but also changes in social status or job reduced the recurrence risk significantly. Changing...

  1. Correlation of Stress Concentration Factors for T-Welded Connections – Finite Element Simulations and Fatigue Behavior

    Directory of Open Access Journals (Sweden)

    Gerardo Terán Méndez

    Full Text Available Abstract The stress concentration factors (SCFs in welded connections usually occur at zones with high stress levels. Stress concentrations reduce the fatigue behavior of welded connections in offshore structures and cracking can develop. By using the grinding technique, cracking can be eliminated. Stress concentration factors are defined as a ratio of maximum stress at the intersection to nominal stress on the brace. Defining the stress concentration factor is an important stage in the fatigue behavior of welded connections. Several approaches have evolved for designing structures with the classical S-N approach for estimating total life. This work correlates to the stress concentration factors of T-welded connections and the fatigue behavior. Stress concentration factors were computed with the finite element employing 3D T-welded connections with intact and grinding depth conditions. Then, T-welded connections were constructed with A36 plate steel and welded with E6013 electrodes to obtain the stress-life (S-N approach. The methodology from previous works was used to compute the SCF and fabricate the T-welded connections. The results indicated that the grinding process could restore the fatigue life of the T-welded connections for SCFs values in the range of 1.29. This value can be considered to be a low SCF value in T-welded connection. However, for higher SCF values, the fatigue life decreased, compromising and reducing the structural integrity of the T-welded connections.

  2. Dysregulation of the transcription factors SOX4, CBFB and SMARCC1 correlates with outcome of colorectal cancer

    DEFF Research Database (Denmark)

    Andersen, C L; Christensen, L L; Thorsen, K

    2009-01-01

    The aim of this study was to identify deregulated transcription factors (TFs) in colorectal cancer (CRC) and to evaluate their relation with the recurrence of stage II CRC and overall survival. Microarray-based transcript profiles of 20 normal mucosas and 424 CRC samples were used to identify 51...... cancers we found that high SOX4 transcript levels correlated with recurrence (HR 2.7; 95% CI, 1.2-6.0; P=0.01). Analyses of approximately 1000 stage I-III adenocarcinomas, by immunohistochemistry, revealed that patients with tumours displaying high levels of CBFB and SMARCC1 proteins had a significantly...

  3. Influences of thickness, scanning velocity and relative humidity on the frictional properties of WS2 nanosheets

    Science.gov (United States)

    Feng, Dongdong; Peng, Jinfeng; Liu, Sisi; Zheng, Xuejun; Yan, Xinyang; He, Wenyuan

    2018-01-01

    Distinguishing with the traditional cantilever mechanics method, we propose the extended cantilever mechanics method to calibrate the lateral calibration factor by using the normal spring constant obtained from atomic force microscopy (AFM) but not the Young’s modulus and the width of the cantilever, before the influences of thickness, scanning velocity and humidity on the frictional properties are investigated via friction measurement performed by the lateral force mode (LFM) of AFM. Tungsten disulfide (WS2) nanosheets were prepared through hydrothermal intercalation and exfoliation route, and AFM and Raman microscope were used to investigate the frictional properties, thickness and crystalline structure. The friction force and coefficient decrease monotonically with the increase of the nanosheet’s thickness, and the friction coefficient minimum value is close to 0.012 when the thickness larger than 5 nm. The friction property variation on the nanosheet’s thickness can be explained by the puckering effect of tip-sheet adhesion according thickness dependence of bending stiffness in the frame of continuum mechanics. The friction force is a constant value 1.7 nN when the scanning speed larger than the critical value 3.10 μm s-1, while it logarithmically increases for the scanning speed less than the critical value. It is easy to understand through the energy dissipation model and the thermally activated effect. The friction force and friction coefficient increase with the relative humidity at the range of 30%-60%, and the latter is at the range of 0.010-0.013. Influence of relative humidity is discussed via the increasing area of the water monolayer during the water adsorption process. The research can not only enrich nanotribology theory, but also prompt two dimensions materials for nanomechanical applications.

  4. Factorization of percolation density correlation functions for clusters touching the sides of a rectangle

    Science.gov (United States)

    Simmons, Jacob J H; Ziff, Robert M; Kleban, Peter

    2009-02-01

    In this paper we consider the density, at a point z = x+iy, of critical percolation clusters that touch the left (PL(z)), right (PR(z)), or both (PLR(z)) sides of a rectangular system, with open boundary conditions on the top and bottom sides. While each of these quantities is non-universal and indeed vanishes in the continuum limit, the ratio C(z)=P_{L R}(z) / \\sqrt {P_L(z) P_R(z) \\Pi_{\\mathrm {h}}} , where Πh is the probability of left-right crossing given by Cardy, is a universal function of z. With wired (fixed) boundary conditions on the left- and right-hand sides, high-precision numerical simulations and theoretical arguments show that C(z) goes to a constant C0 = 27/2 3-3/4 π5/2 Γ(1/3)-9/2 = 1.029 9268... for points far from the ends, and varies by no more than a few per cent for all z values. Thus PLR(z) factorizes over the entire rectangle to very good approximation. In addition, the numerical observation that C(z) depends upon x but not upon y leads to an explicit expression for C(z) via conformal field theory for a long rectangle (semi-infinite strip). We also derive explicit expressions for PL(z), PR(z), and PLR(z) in this geometry, first by assuming y independence and then by a full analysis that obtains these quantities exactly with no assumption on the y behavior. In this geometry we obtain, in addition, the corresponding quantities in the case of open boundary conditions, which allows us to calculate C(z) in the open system. We give some theoretical results for an arbitrary rectangle as well. Our results also enable calculation of the finite-size corrections to the factorization near an isolated anchor point, for the case of clusters anchored at points. Finally, we present numerical results for a rectangle with periodic b.c. in the horizontal direction, and find C(z) that approaches a constant value C1≈1.022.

  5. Factor structure and clinical correlates of the Food Thought Suppression Inventory within treatment seeking obese women with binge eating disorder

    Science.gov (United States)

    Barnes, Rachel D.; Sawaoka, Takuya; White, Marney A.; Masheb, Robin M.; Grilo, Carlos M.

    2013-01-01

    Prior research on the relations among eating behaviors and thought suppression is limited to a measure of general thought suppression, the White Bear Suppression Inventory. To address this limitation, researchers recently validated the Food Thought Suppression Inventory (FTSI). Analyses using this measure suggest that food thought suppression is distinct from and is more predictive of eating disorder psychopathology than is general thought suppression. The FTSI, however, has not yet been validated in clinical samples. The purpose of the current study is to examine the factor structure and clinical correlates of the FTSI within treatment seeking obese women with binge eating disorder (BED; N = 128). Analyses revealed a valid and reliable one-factor measure of food thought suppression that was related to higher levels of eating and general psychopathology. The findings provide evidence for the use of the FTSI with obese women with BED. Future research should examine the psychometric properties of the FTSI within larger and more diverse samples. PMID:23265399

  6. The correlated factors of the uneven performances of the CDM host countries

    Science.gov (United States)

    Zhu, Jinshan

    2012-03-01

    The Kyoto Protocol’s Clean Development Mechanism (CDM) has experienced a rapid growth. Up to 2010, 2763 projects have been registered, standing for about 433 million ton CO2 equivalent (CO2-eq.) of annual carbon credits. However, the performances of CDM host countries are remarkably unbalanced. Previous literature suggested that economic and investment conditions, energy intensity, energy structure, the share of annual carbon credits from high global warming potential (GWP) green house gas (GHG), capacity and institutional buildings of domestic CDM governance can play important roles in promoting CDM. This quantitative analysis shows that domestic economic and investment conditions are the most decisive factors determining the performance of the CDM host countries. Additionally, the influence of carbon intensity of energy consumption is relatively modest, and energy intensity of GDP as well as the share of annual carbon credits from high GWP GHG is less significant. Moreover, several leading CDM countries are not as successful as they seem to be, when the influences of their vast territories, distinguished economic and investment conditions are excluded. Therefore, to simply transplant the CDM governances of these countries can hardly guarantee that other countries will boost their carbon credit outputs.

  7. Etiological factors correlated with temporomandibular disorder in complete denture wearers: a comparative analysis

    Directory of Open Access Journals (Sweden)

    Ricardo Alexandre Zavanelli

    2009-01-01

    Full Text Available Objective: The aim of this study was to make a comparative evaluation of the prevalence of temporomandibular disorder in complete denturewearers, with regard to the etiological factors, such as gender, age, and complete dentures clinical conditions, according to the anamnestic(Ai and clinical (Di dysfunction index, developed by Helkimo.Methods: The randomized sample was composed of 90 institutionalized patients and bimaxillary complete denture wearers, with a mean ageof 67.2 years, who were included in this study. The collected data were tabulated and the Kruskal-Wallis and Chi-square statistical tests were applied, at the level of significance of 5% (p<0.05.Results: Statistically significant difference in the prevalence of temporomandibular disorder was observed with regard to the ages of the current complete dentures, free-way space, wear of the occlusal surfaces of the artificial teeth, and the conditions of retention and stability of the maxillary and mandibular complete dentures, according to both the indexes. Conclusion: The patients who wore complete dentures in adequate clinical conditions presented fewer signs and symptoms of temporomandibular disorder than the patients who wore complete dentures in poor clinical conditions.

  8. Coordination Frictions and Job Heterogeneity

    DEFF Research Database (Denmark)

    Kennes, John; le Maire, Christian Daniel

    This paper develops and extends a dynamic, discrete time, job to worker matching model in which jobs are heterogeneous in equilibrium. The key assumptions of this economic environment are (i) matching is directed and (ii) coordination frictions lead to heterogeneous local labor markets. We de- rive...... a number of new theoretical results, which are essential for the empirical application of this type of model to matched employer-employee microdata. First, we o¤er a robust equilibrium concept in which there is a continu- ous dispersion of job productivities and wages. Second, we show that our model can...... be readily solved with continuous exogenous worker heterogene- ity, where high type workers (high outside options and productivity) earn higher wages in high type jobs and are hired at least as frequently to the better job types as low type workers (low outside options and productivity). Third, we...

  9. Predicting a contact's sensitivity to initial conditions using metrics of frictional coupling

    International Nuclear Information System (INIS)

    Flicek, Robert C.; Hills, David A.; Brake, Matthew Robert W.

    2016-01-01

    This paper presents a method for predicting how sensitive a frictional contact’s steady-state behavior is to its initial conditions. Previous research has proven that if a contact is uncoupled, i.e. if slip displacements do not influence the contact pressure distribution, then its steady-state response is independent of initial conditions, but if the contact is coupled, the steady-state response depends on initial conditions. In this paper, two metrics for quantifying coupling in discrete frictional systems are examined. These metrics suggest that coupling is dominated by material dissimilarity due to Dundurs’ composite material parameter β when β ≥ 0.2, but geometric mismatch becomes the dominant source of coupling for smaller values of β. Based on a large set of numerical simulations with different contact geometries, material combinations, and friction coefficients, a contact’s sensitivity to initial conditions is found to be correlated with the product of the coupling metric and the friction coefficient. For cyclic shear loading, this correlation is maintained for simulations with different contact geometries, material combinations, and friction coefficients. Furthermore, for cyclic bulk loading, the correlation is only maintained when the contact edge angle is held constant.

  10. Correlation of outcome measures with epidemiological factors in thoracolumbar spinal trauma

    Directory of Open Access Journals (Sweden)

    Upendra Bidre

    2007-01-01

    Full Text Available Background : The epidemiological data of a given population on spinal trauma in India is lacking. The present study was undertaken to evaluate the profile of patients with thoracolumbar fractures in a tertiary care hospital in an urban setup. Materials and Methods : Four hundred forty patients with thoracolumbar spinal injuries admitted from January 1990 to May 2000 to the All India Institute of Medical Sciences were included in the analysis. Both retrospective data retrieval and prospective data evaluation of patients were done from January 1998 to May 2000. Epidemiological factors like age, sex and type of injury, mode of transport, time of reporting and number of transfers before admission were recorded. Frankel′s grading was used to assess neurological status. Functional assessment of all patients was done using the FIM™ instrument (Functional Independence Measure. Average follow-up was 33 months (24-41 months. Results : Of the 440 patients, females comprised 17.95% (n=79, while 82.04% (n=361 were males. As many as 40.9% (n=180 of them were in the third decade. Fall from height remained the most common cause 52.3% (n=230. Two hundred sixty (59.1% patients reported within 48 hours. Thirty-two (7.27% patients had single transfer, and all 32 showed complete independence for mobility at final follow-up. 100 of 260 (38.5% patients reporting within 48 hours developed pressure sores, while 114 of 142 (80.28% patients reporting after 5 days developed pressure sores. Conclusion : The present study highlights the magnitude of the problems of our trauma-care and transport system and the difference an effective system can make in the care of spinal injury patients. There is an urgent need for epidemiological data on a larger scale to emphasize the need for a better trauma-care system and pave way for adaptation of well-established trauma-care systems from developed countries.

  11. Can socioeconomic factors account for "atypical" correlations between timing, peak velocity, and intensity of adolescent growth in Taiwanese girls?

    Science.gov (United States)

    Floyd, B.

    2000-01-01

    This study uses longitudinal height records of girls in two urban and one rural area in Taiwan. Individual height records were modeled with the Preece-Baines Model 1 (PB1) function to test two related hypotheses: 1) Taiwanese students who experienced a relatively stable, affluent growth environment from an early age, as judged from parental education and stability of residence type, will have a pattern of correlations for the timing and intensity of the growth spurt similar to those of European and American females; and 2) those students whose parents gained the wherewithal to move from single-story to multi-story dwellings while they were in primary school will have the most atypical patterns. The extent to which these and other sociodemographic factors influence pubertal spurt velocities and increments of adolescent growth were explored as well using multiple regression analyses. Results support the view that rapid socioeconomic change in Taiwan influenced the relationship between the timing and intensity of adolescent growth in stature. Children in the more stable environments in both urban areas had patterns of correlations typical of population samples from developed countries. The most atypical correlations in both areas were found among those who likely experienced the greatest improvement in socioeconomic status during primary school. These represent positive values previously unreported in the literature. Differences in amounts of growth, though in accord with these patterns, were quite small. Am. J. Hum. Biol. 12:102-117, 2000. Copyright 2000 Wiley-Liss, Inc.

  12. Serum levels of brain-derived neurotrophic factor correlate with the number of T2 MRI lesions in multiple sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Comini-Frota, E.R. [Unidade de Neurologia, Hospital Universitário, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Rodrigues, D.H. [Laboratório de Imunofarmacologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Miranda, E.C. [Ecoar Diagnostic Center, Belo Horizonte, MG (Brazil); Brum, D.G. [Hospital das Clínicas,Faculdade de Medicina de Ribeirão Preto,Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Kaimen-Maciel, D.R. [Unidade de Neurologia, Hospital Universitário, Universidade Estadual de Londrina, Londrina, PR (Brazil); Donadi, E.A. [Hospital das Clínicas,Faculdade de Medicina de Ribeirão Preto,Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Teixeira, A.L. [Unidade de Neurologia, Hospital Universitário, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Laboratório de Imunofarmacologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil)

    2011-11-23

    The objective of the present study was to determine if there is a relationship between serum levels of brain-derived neurotrophic factor (BDNF) and the number of T2/fluid-attenuated inversion recovery (T2/FLAIR) lesions in multiple sclerosis (MS). The use of magnetic resonance imaging (MRI) has revolutionized the study of MS. However, MRI has limitations and the use of other biomarkers such as BDNF may be useful for the clinical assessment and the study of the disease. Serum was obtained from 28 MS patients, 18-50 years old (median 38), 21 women, 0.5-10 years (median 5) of disease duration, EDSS 1-4 (median 1.5) and 28 healthy controls, 19-49 years old (median 33), 19 women. BDNF levels were measured by ELISA. T1, T2/FLAIR and gadolinium-enhanced lesions were measured by a trained radiologist. BDNF was reduced in MS patients (median [range] pg/mL; 1160 [352.6-2640]) compared to healthy controls (1640 [632.4-4268]; P = 0.03, Mann-Whitney test) and was negatively correlated (Spearman correlation test, r = -0.41; P = 0.02) with T2/FLAIR (11-81 lesions, median 42). We found that serum BDNF levels were inversely correlated with the number of T2/FLAIR lesions in patients with MS. BDNF may be a promising biomarker of MS.

  13. Seasonal fluctuations of airborne pollen grains count and its correlation with climatic factors from khairpur; sindh, pakistan

    International Nuclear Information System (INIS)

    Perveen, A.; Khan, M.

    2014-01-01

    This is the first aerobiological survey of Khairpur, Sindh. The survey was conducted from January-December, 2011 using Burkard's Seven Days Volumetric Spore trap. A total of 4559 pollen/m3 were recorded belonging to 33 plant families and 41 pollen types. The major pollen types were Poaceae (13.84%), Amaranthaceae/ Chenopodiaceae (10.40%), Cyperus rotundus (7.61%); Prosopis juliflora (6.19%), Brassica campestris (4.91%), Typha angustifolia (4.89%), Tamarix indica (4.43%), Eucalyptus globules (4.28%), Conocarpus erectus (3.73%), Asteraceae (3.01%), Guaicum officinale (2.94%), Azadirachta indica (2.74%), Malvaceae (2.15%) and Phoenix dactylifera (1.84%) constituting more than 70% of total pollen catch. The highest pollen grains concentration was observed in May-2011 with 880 pollen/m3 count while second highest pollen concentration was detected in September 2011 with 682 pollen/m3. The lowest count was found in December- 2011. Climatic factors like wind speed, average temperature, humidity and rainfall were correlated with the pollen counts. Different pollen types showed significant positive correlation with average temperature while negative correlation with humidity and wind speed. (author)

  14. The correlation of the P53 protein expression in invasive cervical carcinoma with prognostic and clinical factors.

    Directory of Open Access Journals (Sweden)

    Eliana Aguiar Petri Nahas

    2012-01-01

    Full Text Available The analysis of p53 protein in cervical carcinoma correlated with clinical and prognostic factors was performed in a retrospective study with p53 expression detection by immunohistochemical technique. 120 slides of patients with squamous cell cancer at the Gynecologic Oncology Clinic and stored in the Department of Pathological Anatom at the School of Medicine of Botucatu were used. Age, ethnicity, parity, smoking habit, oral contraceptive use, age at first intercourse, histology, stage, treatment, and follow-up were the cofactors associated with p53 positivity. Fisher’s exact tests were carried out to analyze associations between p53 and variables, with p < 0.05 as the significant level. The study revealed a 43.3% frequency of patients with stage II disease and p53 positive rate with p = 0.001, and 64.2% frequency with p = 0.024 of patients whose first intercourse occurred between the ages of 15 and 20. These findings show the correlation between stage II disease and age at first intercourse with p53 positive in invasive cervical cancer. Fisher's exact test revelead these cofactors to be statistically significant and there was no association between the protein p53 with others prognostic and analyzed cofactors. The prognostic value of p53 in cervical cancer had been examined, with the conclusion that p53 is correlated to unfavorable prognosis.

  15. Cellular and Tumor Radiosensitivity is Correlated to Epidermal Growth Factor Receptor Protein Expression Level in Tumors Without EGFR Amplification

    International Nuclear Information System (INIS)

    Kasten-Pisula, Ulla; Saker, Jarob; Eicheler, Wolfgang; Krause, Mechthild; Yaromina, Ala; Meyer-Staeckling, Soenke; Scherkl, Benjamin; Kriegs, Malte; Brandt, Burkhard; Grenman, Reidar; Petersen, Cordula; Baumann, Michael; Dikomey, Ekkehard

    2011-01-01

    Purpose: There is conflicting evidence for whether the expression of epidermal growth factor receptor in human tumors can be used as a marker of radioresponse. Therefore, this association was studied in a systematic manner using squamous cell carcinoma (SCC) cell lines grown as cell cultures and xenografts. Methods and Materials: The study was performed with 24 tumor cell lines of different tumor types, including 10 SCC lines, which were also investigated as xenografts on nude mice. Egfr gene dose and the length of CA-repeats in intron 1 were determined by polymerase chain reaction, protein expression in vitro by Western blot and in vivo by enzyme-linked immunosorbent assay, and radiosensitivity in vitro by colony formation. Data were correlated with previously published tumor control dose 50% data after fractionated irradiation of xenografts of the 10 SCC. Results: EGFR protein expression varies considerably, with most tumor cell lines showing moderate and only few showing pronounced upregulation. EGFR upregulation could only be attributed to massive gene amplification in the latter. In the case of little or no amplification, in vitro EGFR expression correlated with both cellular and tumor radioresponse. In vivo EGFR expression did not show this correlation. Conclusions: Local tumor control after the fractionated irradiation of tumors with little or no gene amplification seems to be dependent on in vitro EGFR via its effect on cellular radiosensitivity.

  16. Factors associated with low bone mass in the hemodialysis patients – a cross-sectional correlation study

    Directory of Open Access Journals (Sweden)

    Huang Guey-Shiun

    2009-06-01

    Full Text Available Abstract Background Low bone mass is common in end-stage renal disease patients, especially those undergoing hemodialysis. It can lead to serious bone health problems such as fragility fractures. The purpose of this study is to investigate the risk factors of low bone mass in the hemodialysis patients. Methods Sixty-three subjects on hemodialysis for at least 6 months were recruited from a single center for this cross-sectional study. We collected data by questionnaire survey and medical records review. All subjects underwent a bone mineral density (BMD assay with dual-energy x-ray absorptiometry at the lumbar spine and right hip. Data were statistically analyzed by means of descriptive analysis, independent t test and one way analysis of variance for continuous variables, Pearson product-moment correlation to explore the correlated factors of BMD, and stepwise multiple linear regression to identify the predictors of low bone mass. Results Using WHO criteria as a cutoff point, fifty-one subjects (81% had a T-score lower than -1, of them 8 subjects (13% had osteoporosis with the femoral neck most commonly affected. Regarding risk factors, age, serum alkaline phosphatase (ALP level, and intact parathyroid hormone (iPTH level had significant negative correlations with the femoral neck and lumbar spine BMD. On the other hand, serum albumin level, effective exercise time, and body weight (BW had significant positive correlations with the femoral neck and lumbar spine BMD. Age, effective exercise time, and serum albumin level significantly predicted the femoral neck BMD (R2 × 0.25, whereas BW and the ALP level significantly predicted the lumbar spine BMD (R2 × 0.20. Conclusion This study showed that advanced age, low BW, low serum albumin level, and high ALP and iPTH levels were associated with a low bone mass in the hemodialysis patients. We suggest that regular monitoring of the femoral neck BMD, maintaining an adequate serum albumin level and BW

  17. Thermal-oxidative effect of Kraft lignin antioxidant in polypropylene: Uncovering the key factor using correlation analysis model.

    Science.gov (United States)

    Chen, Kai; Ye, Dezhan; Gu, Shaojin; Zhou, Yingshan

    2018-02-01

    Which factors are crucial to improving lignin antioxidant ability in polymers has been debated over years. Here, the structural effect of natural antioxidant from technical Kraft lignin (KL) on the oxidation induction time (OIT) of KL/polypropylene (PP) was quantitatively investigated using correlation analysis model instead of traditional linear fitting model. The correlation coefficient and significance value of their relationship clearly demonstrated the dominating role of non-condensed Phenolic OH (Ph-OH) in improving KL/PP thermal-oxidation stability, subsequently followed by M¯ n , aliphatic OH/total Ph-OH, condensed Ph-OH and polydispersity. OIT is positive with non-condensed and total Ph-OH, while it declines with increase of the above other factors. Remarkably, the longest OIT (∼90min) was obtained even at extreme loading (0.5wt%), almost ∼911% and ∼201% huge increase in contrast to that of pure PP and crude KL/PP composite, respectively. Meanwhile, the mechanical properties of KL fractions/PP blends can be maintained at the same or better level than that of pure PP, due to strong interfacial adhesion strength. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Phenotypic Assays to Determine Virulence Factors of Uropathogenic Escherichia coli (UPEC) Isolates and their Correlation with Antibiotic Resistance Pattern.

    Science.gov (United States)

    Tabasi, Mohsen; Asadi Karam, Mohammad Reza; Habibi, Mehri; Yekaninejad, Mir Saeed; Bouzari, Saeid

    2015-08-01

    Urinary tract infection caused by uropathogenic Escherichia coli (UPEC) strains is one of the most important infections in the world. UPEC encode widespread virulence factors closely related with pathogenesis of the bacteria. The purpose of this study was to evaluate the presence of different phenotypic virulence markers in UPEC isolates and determine their correlation with antibiotic resistance pattern. UPEC isolates from patients with different clinical symptoms of UTI were collected and screened for biofilm and hemolysin production, mannose resistant, and mannose sensitive hemagglutination (MRHA and MSHA, respectively). In addition, antimicrobial resistance pattern and ESBL-producing isolates were recorded. Of the 156 UPEC isolates, biofilm and hemolysin formation was seen in 133 (85.3%) and 53 (34%) isolates, respectively. Moreover, 98 (62.8%) and 58 (37.2%) isolates showed the presence of Types 1 fimbriae (MSHA) and P fimbriae (MRHA), respectively. Our results also showed a relationship between biofilm formation in UPEC isolated from acute cystitis patients and recurrent UTI cases. Occurrence of UTI was dramatically correlated with the patients' profiles. We observed that the difference in antimicrobial susceptibilities of the biofilm and nonbiofilm former isolates was statistically significant. The UPEC isolates showed the highest resistance to ampicillin, tetracycline, amoxicillin, and cotrimoxazole. Moreover, 26.9% of isolates were ESBL producers. This study indicated that there is a relationship between the phenotypic virulence traits of the UPEC isolates, patients' profiles, and antibiotic resistance. Detection of the phenotypic virulence factors could help to improve understanding of pathogenesis of UPEC isolates and better medical intervention.

  19. Analysis on factors affecting household customers decision in using electricity at peak time and its correlation towards saving electricity

    Science.gov (United States)

    Pasasa, Linus; Marbun, Parlin; Mariza, Ita

    2015-09-01

    The purpose of this paper is to study and analyse the factors affecting customer decisions in using electricity at peak-load hours (between 17.00 to 22.00 WIB) and their behaviors towards electricity conservation in Indonesian household. The underlying rationale is to influence a reduction in energy consumption by stimulating energy saving behaviors, thereby reducing the impact of energy use on the environment. How is the correlation between the decisions in using electricity during peak load hours with the household customer's behavior towards saving electricity? The primary data is obtained by distributing questionnaires to customers of PT. PLN Jakarta Raya and Tangerang Distribution from Household segment. The data is analysed using the Structural Equation Model (SEM) and AMOS Software. The research is finding that all factors (Personal, Social, PLN Services, Psychological, and Cultural) are positively influence customer decision in using electricity at peak load hours. There is a correlation between the decisions in using electricity during peak load hours with the household customer's behavior towards saving electricity.

  20. A Geographic Information System (GIS-Based Analysis of Social Capital Data: Landscape Factors That Correlate