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Sample records for extrinsically toughened dra

  1. Curing behaviors and properties of an extrinsic toughened epoxy/anhydride system and an intrinsic toughened epoxy/anhydride system

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Mengjin; Liu, Jialin; Li, Xiangyuan [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Cheng, Jue, E-mail: chengjue@mail.buct.edu.cn [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Junying, E-mail: zjybuct@gmail.com [Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China)

    2013-02-20

    Highlights: ► Two curing systems (ETRS and ITRS) with similar chemical composite were prepared. ► The curing kinetics of the ETRS and the novel ITRS were comparatively studied. ► Crosslinking density can affect the kinetic schemes of the two curing systems. ► Their mechanical properties and thermal stabilities were also comparatively studied. ► Crosslinking density may play an influential role in mechanical properties. - Abstract: The curing kinetics of an extrinsic toughened epoxy (mixture of diglycidyl ether of bisphenol-A and 1,4-butanediol epoxy resin, DGEBA/DGEBD) and an intrinsic toughened epoxy (ethoxylated bisphenol-A epoxy resin with two oxyethylene units, DGEBAEO-2) using hexahydrophthalic anhydride (HHPA) as curing agent and tris-(dimethylaminomethyl) phenol (DMP-30) as accelerator were comparatively studied by non-isothermal DSC with a model-fitting Málek approach and a model-free advanced isoconversional method of Vyazovkin. The dynamic mechanical properties and thermal stabilities of the cured materials were investigated by DMTA and TGA, respectively. The results showed that Šesták–Berggren model can generally simulate well the reaction rates of these two systems. The activation energy of DGEBA/DGEBD/HHPA/DMP-30 at high fractional conversion changed much higher than that of DGEBAEO-2/HHPA/DMP-30, indicating the increased steric hindrance mainly affected the reaction kinetic scheme of DGEBA/DGEBD/HHPA/DMP-30. The T{sub g} and storage moduli of cured DGEBAEO-2/HHPA/DMP-30 were lower than those of cured DGEBA/DGEBD/HHPA/DMP-30 according to DMTA while TGA showed that the thermal stabilities of these two cured systems were similar.

  2. EPOXY RESIN TOUGHENED BY THERMOPLASTICS

    Institute of Scientific and Technical Information of China (English)

    FU Zengli; SUN Yishi

    1989-01-01

    Two kinds of tough ductile heatresisting thermoplastic, namely bisphenol A polysulfone (PSF) and polyethersulfone (PES) were used to toughen thermoset epoxy resin. A systematic study on the relationship between the molecular weight and the terminal group of the thermoplastic modifier and the fracture toughness of the modified resin was carried out. The morphology of PSF modified epoxy resin was surveyed. With the same kind of PSF the structure of the epoxy resin and the toughening effect of PSF was also investigated. The fractography of PSF, particle modified epoxy was examined in detail with SEM. The contribution of every possible energy absorption process has been discussed. Crack pinning mechanism seems to be the most important toughening mechanism for tough ductile thermoplastic PSF particle modified epoxy system.

  3. Extrinsic Curvature Embedding Diagrams

    CERN Document Server

    Lu, J L

    2003-01-01

    Embedding diagrams have been used extensively to visualize the properties of curved space in Relativity. We introduce a new kind of embedding diagram based on the {\\it extrinsic} curvature (instead of the intrinsic curvature). Such an extrinsic curvature embedding diagram, when used together with the usual kind of intrinsic curvature embedding diagram, carries the information of how a surface is {\\it embedded} in the higher dimensional curved space. Simple examples are given to illustrate the idea.

  4. Effect of Time and Temperature on Transformation Toughened Zirconias.

    Science.gov (United States)

    1987-06-01

    TTZ) and tetragonal airconia polycrystal ( TZP ), as well as sirconla toughened alumina (ZTA), among others. Zirconia based materials are of interest due... zirconia case, two ftctors that affect the analysis are the difficulty in resolving the tetragonal (101) and cubic (111) peaks when copper radiation is...The materials were magnesia stabilized transforma- tion toughened zirconia , yttria stabilized tetragonal zirconia polycrystal, and zirconia toughened

  5. EPOXY RESINS TOUGHENED WITH CARBOXYL TERMINATED POLYETHERS

    Institute of Scientific and Technical Information of China (English)

    YU Yunchao; LI Yiming

    1983-01-01

    Carboxyl terminated polyethers, the adducts of hydroxyl terminated polytetrahydrofuran and maleic anhydride, were used as toughener for epoxy resins. The morphology of the toughened resins was investigated by means of turbidity measurement, dynamic mechanical testing and scanning electron microscope observation. It turned out that the molecular weight and the carboxyl content of the polyether and the cure conditions are important factors, which affect the particle size of the polyether-rich domains and, in turn, the mechanical properties of the cured resin. Carboxyl terminated polytetrahydrofurans have a low glass transition temperature, and in appropriate amount they do not affect the thermal resistance of the resin. These advantages make them preferable as toughener for epoxy resins.

  6. Modeling of Residual Stresses In Toughened Glass

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik

    2006-01-01

    -depth knowledge of the residual stresses in toughened glass near holes and edges where the total stress state is a combination of contact stresses and residual stresses. The present paper, presenting the derivation and results for a model predicting the residual stresses in a glass plate far from edges and holes......, is a step towards such a model. The model is based on the Instant Freeze concept with a few modifications. Current work, using a partial differential equation approach for the modeling and state-of-the-art in modeling residual stresses in glass is briefly presented, and a short description of the toughening...

  7. LUT observations of the mass-transferring binary AI Dra

    Science.gov (United States)

    Liao, Wenping; Qian, Shengbang; Li, Linjia; Zhou, Xiao; Zhao, Ergang; Liu, Nianping

    2016-06-01

    Complete UV band light curve of the eclipsing binary AI Dra was observed with the Lunar-based Ultraviolet Telescope (LUT) in October 2014. It is very useful to adopt this continuous and uninterrupted light curve to determine physical and orbital parameters of the binary system. Photometric solutions of the spot model are obtained by using the W-D (Wilson and Devinney) method. It is confirmed that AI Dra is a semi-detached binary with secondary component filling its critical Roche lobe, which indicates that a mass transfer from the secondary component to the primary one should happen. Orbital period analysis based on all available eclipse times suggests a secular period increase and two cyclic variations. The secular period increase was interpreted by mass transfer from the secondary component to the primary one at a rate of 4.12 ×10^{-8}M_{⊙}/yr, which is in agreement with the photometric solutions. Two cyclic oscillations were due to light travel-time effect (LTTE) via the presence of two cool stellar companions in a near 2:1 mean-motion resonance. Both photometric solutions and orbital period analysis confirm that AI Dra is a mass-transferring binary, the massive primary is filling 69 % of its critical Roche lobe. After the primary evolves to fill the critical Roche lobe, the mass transfer will be reversed and the binary will evolve into a contact configuration.

  8. Rigid particle toughening of aliphatic polyketone

    NARCIS (Netherlands)

    Zuiderduin, W.C.J.; Huetink, Han; Gaymans, R.J.

    2006-01-01

    The influence of precipitated calcium carbonate particles on the toughening behaviour of aliphatic polyketone has been studied. The calcium carbonate particles had a particle size of 0.7 mm and a stearic acid coating (1%). Composites of 0e31.5 vol% CaCO3 content have been compounded and injection

  9. Extrinsic allergic alveolitis.

    Science.gov (United States)

    Ismail, Tengku; McSharry, Charles; Boyd, Gavin

    2006-05-01

    Extrinsic allergic alveolitis (also known as hypersensitivity pneumonitis) is caused by repeated inhalation of mainly organic antigens by sensitized subjects. This induces a hypersensitivity response in the distal bronchioles and alveoli and subjects may present clinically with a variety of symptoms. The aims of this review are to describe the current concepts of the immunological response, the diverse clinical presentation of this disease, the relevant investigations and management, and areas for future studies.

  10. Effects of over-expression of the regulatory enzymes DraT and DraG on the ammonium-dependent post-translational regulation of nitrogenase reductase in Azospirillum brasilense.

    Science.gov (United States)

    Huergo, Luciano F; Souza, Emanuel M; Steffens, Maria B R; Yates, M Geoffrey; Pedrosa, Fábio O; Chubatsu, Leda S

    2005-03-01

    Nitrogen fixation in Azospirillum brasilense is regulated at transcriptional and post-translational levels. Post-translational control occurs through the reversible ADP-ribosylation of dinitrogenase reductase (Fe Protein), mediated by the dinitrogenase reductase ADP-ribosyltransferase (DraT) and dinitrogenase reductase glycohydrolase (DraG). Although the DraT and DraG activities are regulated in vivo, the molecules responsible for such regulation remain unknown. We have constructed broad-host-range plasmids capable of over-expressing, upon IPTG induction, the regulatory enzymes DraT and DraG as six-histidine-N-terminal fused proteins (His). Both DraT-His and DraG-His are functional in vivo. We have analyzed the effects of DraT-His and DraG-His over-expression on the post-translational modification of Fe Protein. The DraT-His over-expression led to Fe Protein modification in the absence of ammonium addition, while cells over-expressing DraG-His showed only partial ADP-ribosylation of Fe Protein by adding ammonium. These results suggest that both DraT-His and DraG-His lose their regulation upon over-expression, possible by titrating out negative regulators.

  11. Modeling of Residual Stresses In Toughened Glass

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik

    2006-01-01

    The motivation for this work is the need for more extended guidelines considering structural design of glass structures. Realistic models predicting the strength of bolted connections are a step towards improvement of such guidelines. Improvement of guidelines for bolted connections require in......-depth knowledge of the residual stresses in toughened glass near holes and edges where the total stress state is a combination of contact stresses and residual stresses. The present paper, presenting the derivation and results for a model predicting the residual stresses in a glass plate far from edges and holes......, is a step towards such a model. The model is based on the Instant Freeze concept with a few modifications. Current work, using a partial differential equation approach for the modeling and state-of-the-art in modeling residual stresses in glass is briefly presented, and a short description of the toughening...

  12. First analysis of eight Algol-type binaries: EI Aur, XY Dra, BP Dra, DD Her, VX Lac, WX Lib, RZ Lyn, and TY Tri

    CERN Document Server

    Zasche, P

    2015-01-01

    The available photometry from the online databases were used for the first light curve analysis of eight eclipsing binary systems EI Aur, XY Dra, BP Dra, DD Her, VX Lac, WX Lib, RZ Lyn, and TY Tri. All these stars are of Algol-type, having the detached components and the orbital periods from 0.92 to 6.8 days. For the systems EI Aur and BP Dra the large amount of the third light was detected during the light curve solution. Moreover, 468 new times of minima for these binaries were derived, trying to identify the period variations. For the systems XY Dra and VX Lac the third bodies were detected with the periods 17.7, and 49.3 years, respectively.

  13. Two-Stage MAS Technique for Analysis of DRA Elements and Arrays on Finite Ground Planes

    DEFF Research Database (Denmark)

    Larsen, Niels Vesterdal; Breinbjerg, Olav

    2007-01-01

    A two-stage Method of Auxiliary Sources (MAS) technique is proposed for analysis of dielectric resonator antenna (DRA) elements and arrays on finite ground planes (FGPs). The problem is solved by first analysing the DRA on an infinite ground plane (IGP) and then using this solution to model the FGP...... problem....

  14. Formalizing MedDRA to support semantic reasoning on adverse drug reaction terms.

    Science.gov (United States)

    Bousquet, Cédric; Sadou, Éric; Souvignet, Julien; Jaulent, Marie-Christine; Declerck, Gunnar

    2014-06-01

    Although MedDRA has obvious advantages over previous terminologies for coding adverse drug reactions and discovering potential signals using data mining techniques, its terminological organization constrains users to search terms according to predefined categories. Adding formal definitions to MedDRA would allow retrieval of terms according to a case definition that may correspond to novel categories that are not currently available in the terminology. To achieve semantic reasoning with MedDRA, we have associated formal definitions to MedDRA terms in an OWL file named OntoADR that is the result of our first step for providing an "ontologized" version of MedDRA. MedDRA five-levels original hierarchy was converted into a subsumption tree and formal definitions of MedDRA terms were designed using several methods: mappings to SNOMED-CT, semi-automatic definition algorithms or a fully manual way. This article presents the main steps of OntoADR conception process, its structure and content, and discusses problems and limits raised by this attempt to "ontologize" MedDRA.

  15. ELASTOMERIC REACTIVE MICROGELS AS TOUGHENER FOR EPOXY ADHESIVES

    Institute of Scientific and Technical Information of China (English)

    ZHU Zheng; XUE Ruilan; YU Yunchao

    1987-01-01

    Elastomeric reactive microgels were evaluated as toughener for epoxy adhesives. It turned out that elastomeric microgels can improve lap shear strength and peel strength greatly. The glass transition temperature of the resin matrix was not affected by the presence of dispersed microgel particles, and thus the microgel-toughened adhesives have a good bond strength at elevated temperatures.

  16. The near-contact binary star RZ Dra revisited

    Science.gov (United States)

    Erdem, A.; Zola, S.; Winiarski, M.

    2011-01-01

    This paper presents the absolute parameters of RZ Dra. New CCD observations were made at the Mt. Suhora Observatory in 2007. Two photometric data sets (1990 BV and 2007 BVRI) were analysed using modern light-curve synthesis methods. Large asymmetries in the light curves may be explained in terms of a dark starspot on the primary component, an A6 type star. Due to this magnetic activity, the primary component would appear to belong to the class of Ap-stars and would show small amplitude with δ Scuti-type pulsations. With this in mind, a time-series analysis of the residual light curves was made. However, we found no evidence of pulsation behaviour in RZ Dra. Combining the solutions of our light curves and Rucinski et al. (2000)'s radial velocity curves, the following absolute parameters of the components were determined: M1 = 1.63 ± 0.03 M ⊙, M2 = 0.70 ± 0.02 M ⊙, R1 = 1.65 ± 0.02R ⊙, R2 = 1.15 ± 0.02 R ⊙, L1 = 9.72 ± 0.30 L ⊙ and L2 = 0.74 ± 0.10 L ⊙. The distance to RZ Dra was calculated as 400 ± 25 pc, taking into account interstellar extinction. The orbital period of the system was studied using updated O- C information. It was found that the orbital period varied in its long-period sinusoidal form, superimposed on a downward parabola. The parabolic term shows a secular period decrease at a slow rate of 0.06 ± 0.02 s per century and is explained by the mass loss via magnetized wind of the Ap-star primary. The tilted sinusoidal form of the period variation may be considered as an apparent change and may be interpreted in terms of the light-time effect due to the presence of a third body.

  17. Trans-species polymorphism and selection in the MHC class II DRA genes of domestic sheep.

    Directory of Open Access Journals (Sweden)

    Keith T Ballingall

    Full Text Available Highly polymorphic genes with central roles in lymphocyte mediated immune surveillance are grouped together in the major histocompatibility complex (MHC in higher vertebrates. Generally, across vertebrate species the class II MHC DRA gene is highly conserved with only limited allelic variation. Here however, we provide evidence of trans-species polymorphism at the DRA locus in domestic sheep (Ovis aries. We describe variation at the Ovar-DRA locus that is far in excess of anything described in other vertebrate species. The divergent DRA allele (Ovar-DRA*0201 differs from the sheep reference sequences by 20 nucleotides, 12 of which appear non-synonymous. Furthermore, DRA*0201 is paired with an equally divergent DRB1 allele (Ovar-DRB1*0901, which is consistent with an independent evolutionary history for the DR sub-region within this MHC haplotype. No recombination was observed between the divergent DRA and B genes in a range of breeds and typical levels of MHC class II DR protein expression were detected at the surface of leukocyte populations obtained from animals homozygous for the DRA*0201, DRB1*0901 haplotype. Bayesian phylogenetic analysis groups Ovar-DRA*0201 with DRA sequences derived from species within the Oryx and Alcelaphus genera rather than clustering with other ovine and caprine DRA alleles. Tests for Darwinian selection identified 10 positively selected sites on the branch leading to Ovar-DRA*0201, three of which are predicted to be associated with the binding of peptide antigen. As the Ovis, Oryx and Alcelaphus genera have not shared a common ancestor for over 30 million years, the DRA*0201 and DRB1*0901 allelic pair is likely to be of ancient origin and present in the founding population from which all contemporary domestic sheep breeds are derived. The conservation of the integrity of this unusual DR allelic pair suggests some selective advantage which is likely to be associated with the presentation of pathogen antigen to T

  18. RHEOLOGICAL BEHAVIOR OF KAOLIN TOUGHENED POLYPROPYLENE COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    OU Yuchun; FANG Xiaoping; FENG Yupeng

    1997-01-01

    The relation between the rheological behavior and various interfacial properties of Kaolin rigid particle toughened polypropylene(PP/Kaolin) composites were studied by means of parallel-plate rheometer, melt flow rate apparatus, scanning electron microscopy (SEM) and other testing methods. The results show that addition of interfacial modifier to PP/Kaolin composites is advantageous to homogeneous dispersion of filler in PP matrix,formation of flexible interlayer between Kaolin particles and PP matrix and improvement of the melt processibility of the composites.

  19. Glass ceramic toughened with tetragonal zirconia

    Science.gov (United States)

    Keefer, Keith D.; Michalske, Terry A.

    1986-01-01

    A phase transformation-toughened glass ceramic and a process for making it are disclosed. A mixture of particulate network-forming oxide, network-modifying oxide, and zirconium oxide is heated to yield a homogeneous melt, and this melt is then heat-treated to precipitate an appreciable quantity of tetragonal zirconia, which is retained at ambient temperature to form a phase transformation-toughened glass ceramic. Nucleating agents and stabilizing agents may be added to the mixture to facilitate processing and improve the ceramic's properties. Preferably, the mixture is first melted at a temperature from 1200.degree. to 1700.degree. C. and is then heat-treated at a temperature within the range of 800.degree. to 1200.degree. C. in order to precipitate tetragonal ZrO.sub.2. The composition, as well as the length and temperature of the heat-treatment, must be carefully controlled to prevent solution of the precipitated tetragonal zirconia and subsequent conversion to the monoclinic phase.

  20. Toughening behavior in ceramics and cermets

    Energy Technology Data Exchange (ETDEWEB)

    Becher, P.F.; Sun, E.Y.; Hsueh, C.H.; Plucknett, K.P. [Oak Ridge National Lab., TN (United States); Kim, H.D. [Korean Inst. of Machinery and Materials, Changwon (Korea, Republic of); Hirao, K.; Brito, M. [National Industrial Research Inst., Nagoya (Japan)

    1998-10-01

    The development of high strength ({ge} 1 GPa), high toughness ({ge} 10 MPa {radical}m) ceramic systems is being examined using two approaches. In silicon nitride, toughening is achieved by the introduction of large prismatic shaped grains dispersed in a fine grain matrix. For the system examined herein, both the microstructure and the composition must be controlled. A distinctly bimodal distribution of grain diameters combined with controlled yttria to alumina ratio in additives to promote interfacial debonding is required. Using a cermet approach, ductile Ni{sub 3}Al-bonded TiC exhibited toughening due to plastic deformation within the Ni{sub 3}Al binder phase assisted by interfacial debonding and cleavage of TiC grains. The TiC-Ni{sub 3}Al cermets have toughness values equal to those of the WC-Co cermets. Furthermore, the TiC-Ni{sub 3}Al cermets exhibit high strengths that are retained in air to temperatures of {approximately} 1,000 C.

  1. MN Dra - In-the-Gap Dwarf Nova With Negative Superhumps

    CERN Document Server

    Pavlenko, Elena; Andreev, Max; Sklyanov, Alexandr; Zubareva, Alexandra; Samsonov, Denis; Voloshina, Irina; Metlov, Vladimir; Shugarov, Sergey; Parakhin, Nikolay; Golovin, Alex; Antoniuk, Oksana

    2011-01-01

    The multi-site photometric observations of MN Dra were made over 77 nights in August-November, 2009. The total exposure was 433 hours. During this time the binary underwent two superoutbursts and five normal outbursts. During the course of first superoutburst period of positive superhumps decreased with extremely large $\\dot P = -1.5 \\times 1.0^{-4}$ for SU UMa-like dwarf novae, confirming known behavior of MN Dra [1]. Between the superoutbursts MN Dra displayed negative superhumps. Their period changed cyclically around 0.096-day value.

  2. ProClaT, a new bioinformatics tool for in silico protein reclassification: case study of DraB, a protein coded from the draTGB operon in Azospirillum brasilense.

    Science.gov (United States)

    Rubel, Elisa Terumi; Raittz, Roberto Tadeu; Coimbra, Nilson Antonio da Rocha; Gehlen, Michelly Alves Coutinho; Pedrosa, Fábio de Oliveira

    2016-12-15

    Azopirillum brasilense is a plant-growth promoting nitrogen-fixing bacteria that is used as bio-fertilizer in agriculture. Since nitrogen fixation has a high-energy demand, the reduction of N2 to NH4(+) by nitrogenase occurs only under limiting conditions of NH4(+) and O2. Moreover, the synthesis and activity of nitrogenase is highly regulated to prevent energy waste. In A. brasilense nitrogenase activity is regulated by the products of draG and draT. The product of the draB gene, located downstream in the draTGB operon, may be involved in the regulation of nitrogenase activity by an, as yet, unknown mechanism. A deep in silico analysis of the product of draB was undertaken aiming at suggesting its possible function and involvement with DraT and DraG in the regulation of nitrogenase activity in A. brasilense. In this work, we present a new artificial intelligence strategy for protein classification, named ProClaT. The features used by the pattern recognition model were derived from the primary structure of the DraB homologous proteins, calculated by a ProClaT internal algorithm. ProClaT was applied to this case study and the results revealed that the A. brasilense draB gene codes for a protein highly similar to the nitrogenase associated NifO protein of Azotobacter vinelandii. This tool allowed the reclassification of DraB/NifO homologous proteins, hypothetical, conserved hypothetical and those annotated as putative arsenate reductase, ArsC, as NifO-like. An analysis of co-occurrence of draB, draT, draG and of other nif genes was performed, suggesting the involvement of draB (nifO) in nitrogen fixation, however, without the definition of a specific function.

  3. Fatigue Crack Propagation Behavior of Rubber-toughened Epoxy Resin

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Fatigue crack propagation (FCP) behaviors of mass fraction 15% CTBN (carboxyl-terminated butadiene-acrylonitrile), 15% Qishi toughening-agent toughened anhydride-cured epoxy resins (EP), and pure anhydride-cured EP were measured. The results showed that the two main toughening mechanisms, localized shear yielding and void plastics growth, which occurred near the threshold region because the rubber size is much less than the plastics size at the crack front, improved the near threshold FCP behavior and increased the threshold. The stable FCP behavior was obviously improved with the FCP rates decreased to less than 21%.

  4. Thin films and coatings toughening and toughness characterization

    CERN Document Server

    Zhang, Sam

    2015-01-01

    Thin Films and Coatings: Toughening and Toughness Characterization captures the latest developments in the toughening of hard coatings and in the measurement of the toughness of thin films and coatings. Featuring chapters contributed by experts from Australia, China, Czech Republic, Poland, Singapore, Spain, and the United Kingdom, this first-of-its-kind book:Presents the current status of hard-yet-tough ceramic coatingsReviews various toughness evaluation methods for films and hard coatingsExplores the toughness and toughening mechanisms of porous thin films and laser-treated surfacesExamines

  5. The Mass-Loss History of UX Dra and Other AGB Stars as Probed by Herschel

    Science.gov (United States)

    Mecina, M.; Kerschbaum, F.; Ladjal, D.; Ottensamer, R.; Luntzer, A.; Mayer, A.; Groenewegen, M. A. T.; Blommaert, J. A. D. L.; Baumann, B.; Decin, L.; Klotz, D.; Vandenbussche, B.; Waelkens, C.; Posch, T.

    2011-09-01

    Out of a sample of AGB stars showing detached shells detected by the PACS instrument on-board the Herschel Space Observatory, the case of UX Dra is presented as an example. The derivation of basic parameters is described.

  6. ELA-DRA polymorphisms are not associated with Equine Arteritis Virus infection in horses from Argentina.

    Science.gov (United States)

    Kalemkerian, P B; Metz, G E; Peral-Garcia, P; Echeverria, M G; Giovambattista, G; Díaz, S

    2012-12-01

    Polymorphisms at Major Histocompatibility Complex (MHC) genes have been associated with resistance/susceptibility to infectious diseases in domestic animals. The aim of this investigation was to evaluate whether polymorphisms of the DRA gene the Equine Lymphocyte Antigen is associated with susceptibility to Equine Arteritis Virus (EAV) infection in horses in Argentina. The equine DRA gene was screened for polymorphisms using Pyrosequencing® Technology which allowed the detection of three ELA-DRA exon 2 alleles. Neither allele frequencies nor genotypic differentiation exhibited any statistically significant (P-values=0.788 and 0.745) differences between the EAV-infected and no-infected horses. Fisher's exact test and OR calculations did not show any significant association. As a consequence, no association could be established between the serological condition and ELA-DRA.

  7. Fracture simulation for zirconia toughened alumina microstructure

    CERN Document Server

    Kim, Kyungmok; Forest, Bernard

    2013-01-01

    Purpose - The purpose of this paper is to describe finite element modelling for fracture and fatigue behaviour of zirconia toughened alumina microstructures. Design/methodology/approach - A two-dimensional finite element model is developed with an actual $Al{_2}O{_3}$ - 10 vol% $ZrO{_2}$ microstructure. A bilinear, time-independent cohesive zone law is implemented for describing fracture behaviour of grain boundaries. Simulation conditions are similar to those found at contact between a head and a cup of hip prosthesis. Residual stresses arisen from the mismatch of thermal coefficient between grains are determined. Then, effects of a micro-void and contact stress magnitude are investigated with models containing residual stresses. For the purpose of simulating fatigue behaviour, cyclic loadings are applied to the models. Findings - Results show that crack density is gradually increased with increasing magnitude of contact stress or number of fatigue cycles. It is also identified that a micro-void brings about...

  8. Extrinsic electromagnetic chirality in metamaterials

    OpenAIRE

    Plum, E.; Fedotov, V. A.; Zheludev, N. I.

    2009-01-01

    Three- and two-dimensional chirality arising from the mutual orientation of non-chiral planar metamaterial structures and the incident electromagnetic wave (extrinsic chirality) lead to pronounced optical activity, circular dichroism and asymmetric transmission indistinguishable from those seen in media consisting of three- and two-dimensionally chiral molecules (intrinsic chirality).

  9. Transcellular oxalate and Cl- absorption in mouse intestine is mediated by the DRA anion exchanger Slc26a3, and DRA deletion decreases urinary oxalate.

    Science.gov (United States)

    Freel, Robert W; Whittamore, Jonathan M; Hatch, Marguerite

    2013-10-01

    Active transcellular oxalate transport in the mammalian intestine contributes to the homeostasis of this important lithogenic anion. Several members of the Slc26a gene family of anion exchangers have a measurable oxalate affinity and are expressed along the gut, apically and basolaterally. Mouse Slc26a6 (PAT1) targets to the apical membrane of enterocytes in the small intestine, and its deletion results in net oxalate absorption and hyperoxaluria. Apical exchangers of the Slc26a family that mediate oxalate absorption have not been established, yet the Slc26a3 [downregulated in adenoma (DRA)] protein is a candidate mediator of oxalate uptake. We evaluated the role of DRA in intestinal oxalate and Cl(-) transport by comparing unidirectional and net ion fluxes across short-circuited segments of small (ileum) and large (cecum and distal colon) intestine from wild-type (WT) and DRA knockout (KO) mice. In WT mice, all segments demonstrated net oxalate and Cl(-) absorption to varying degrees. In KO mice, however, all segments exhibited net anion secretion, which was consistently, and solely, due to a significant reduction in the absorptive unidirectional fluxes. In KO mice, daily urinary oxalate excretion was reduced 66% compared with that in WT mice, while urinary creatinine excretion was unchanged. We conclude that DRA mediates a predominance of the apical uptake of oxalate and Cl(-) absorbed in the small and large intestine of mice under short-circuit conditions. The large reductions in urinary oxalate excretion underscore the importance of transcellular intestinal oxalate absorption, in general, and, more specifically, the importance of the DRA exchanger in oxalate homeostasis.

  10. Effect of Genetic Diversity in Swine Leukocyte Antigen-DRA Gene on Piglet Diarrhea

    Science.gov (United States)

    Huang, Xiaoyu; Yang, Qiaoli; Yuan, Junhu; Liu, Lixia; Sun, Wenyang; Jiang, Yingdi; Zhao, Shengguo; Zhang, Shengwei; Huang, Wangzhou; Gun, Shuangbao

    2016-01-01

    The swine leukocyte antigens (SLAs) are the multigene families related to immune responses. Little is known about the effect of the DRA gene on diarrheal disease. This study reported the genetic diversity of the DRA gene in exons 1, 3 and 4 in 290 Chinese Yantai black pigs. No variation was identified in exon 3. In exon 1, three genotypes and two alleles were identified, generated by two single nucleotide polymorphisms (SNPs). In exon 4, there were eight genotypes and five alleles containing seven SNPs were detected with four SNPs being novel SNPs. The low polymorphism found in swine DRA is consistent with the concept that the DRA gene is highly conserved among all mammalian species. Statistical analyses indicated that the genotypes of exon 1 were not significantly associated with piglet diarrhea (p > 0.05); however, genotypes C4C4 (1.80 ± 0.33) and A4E4 (1.66 ± 0.25) of exon 4 were significantly susceptible to diarrhea (p < 0.01). These indicate that the particular genotypes of the DRA gene are susceptible to diarrheal disease, which provides valuable information for disease-resistance breeding in swine. PMID:27429004

  11. Effect of Genetic Diversity in Swine Leukocyte Antigen-DRA Gene on Piglet Diarrhea

    Directory of Open Access Journals (Sweden)

    Xiaoyu Huang

    2016-07-01

    Full Text Available The swine leukocyte antigens (SLAs are the multigene families related to immune responses. Little is known about the effect of the DRA gene on diarrheal disease. This study reported the genetic diversity of the DRA gene in exons 1, 3 and 4 in 290 Chinese Yantai black pigs. No variation was identified in exon 3. In exon 1, three genotypes and two alleles were identified, generated by two single nucleotide polymorphisms (SNPs. In exon 4, there were eight genotypes and five alleles containing seven SNPs were detected with four SNPs being novel SNPs. The low polymorphism found in swine DRA is consistent with the concept that the DRA gene is highly conserved among all mammalian species. Statistical analyses indicated that the genotypes of exon 1 were not significantly associated with piglet diarrhea (p > 0.05; however, genotypes C4C4 (1.80 ± 0.33 and A4E4 (1.66 ± 0.25 of exon 4 were significantly susceptible to diarrhea (p < 0.01. These indicate that the particular genotypes of the DRA gene are susceptible to diarrheal disease, which provides valuable information for disease-resistance breeding in swine.

  12. Extrinsic incentives and tax compliance

    OpenAIRE

    Sour, Laura; Gutiérrez Andrade, Miguel Ángel

    2011-01-01

    This paper models the impact of extrinsic incentives in a tax compliance model. It also provides experimental evidence that confirms the existence of a positive relationship between rewards and tax compliance. If individuals are audited, rewards for honest taxpayers are effective in increasing the level of tax compliance. These results are particularly relevant in countries where there is little respect for tax law since rewards can contribute to crowding in the intrinsic motivation to comply.

  13. Extrinsic incentives and tax compliance

    OpenAIRE

    Sour, Laura; Gutiérrez Andrade, Miguel Ángel

    2011-01-01

    This paper models the impact of extrinsic incentives in a tax compliance model. It also provides experimental evidence that confirms the existence of a positive relationship between rewards and tax compliance. If individuals are audited, rewards for honest taxpayers are effective in increasing the level of tax compliance. These results are particularly relevant in countries where there is little respect for tax law since rewards can contribute to crowding in the intrinsic motivation to comply.

  14. A test case of the deformation rate analysis (DRA) stress measurement method

    Energy Technology Data Exchange (ETDEWEB)

    Dight, P.; Hsieh, A. [Australian Centre for Geomechanics, Univ. of WA, Crawley (Australia); Johansson, E. [Saanio and Riekkola Oy, Helsinki (Finland); Hudson, J.A. [Rock Engineering Consultants (United Kingdom); Kemppainen, K.

    2012-01-15

    As part of Posiva's site and ONKALO investigations, the in situ rock stress has been measured by a variety of techniques, including hydraulic fracturing, overcoring, and convergence measurements. All these techniques involve direct measurements in a drillhole or at the rock surface. An alternative method is to test drillhole core in a way that enables estimation of the magnitudes and orientations of the in situ rock stress. The Kaiser Effect (KE) and Deformation Rate Analysis (DRA) are two ways to do this. In the work reported here, a 'blind' DRA test was conducted on core obtained from the POSE (Posiva's Olkiluoto Spalling Experiment) niche in the ONKALO. The term 'blind' means that the two first authors of this report, who conducted the tests at the Australian Centre for Geomechanics, did not know the depths below surface at which the cores had been obtained. The results of this DRA Test Case are presented, together with an explanation of the DRA procedure. Also, additional information that would help in such DRA testing and associated analysis is explained. One of the problems in comparing the DRA results with the known Olkiluoto stress field is that the latter is highly variable across the site, as experienced by the previous in situ stress measurements and as predicted by numerical analysis. The variability is mainly caused by the presence of the large brittle deformation zones which perturb the local stress state. However, this variability reduces with depth and the stress field becomes more stable at the {approx} 350 m at which the drillhole cores were obtained. Another compounding difficulty is that the stress quantity, being a second order tensor, requires six independent components for its specification. In other words, comparison of the DRA results and the known stress field requires comparison of six different quantities. In terms of the major principal stress orientation, the DRA results predict an orientation completely

  15. Wide Bandgap Extrinsic Photoconductive Switches

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, James S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2013-07-03

    Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6HSiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators.

  16. Quantitative characterization of toughening mechanisms of rubber modified polymers

    Institute of Scientific and Technical Information of China (English)

    朱晓光; 漆宗能; 徐虎; 李刚; 蔡忠龙; C.L.Choy

    1997-01-01

    The volume changes of rubber modified polymers under creep at room temperature were successfully used to characterize the toughening mechanisms of blends with brittle polymer matrices such as high impact polystyrene.This approach cannot be applied to pseudo-ductile polymers such as polypropylene and polyamide,because they are ductile when stretched at low speed at room temperature.Based on the time-temperature equivalence princi ple,the volume change at low temperature is proposed to characterize quantitatively the toughening mechanisms of polymer blends with ductile matrices,which is illustrated by applying this approach to rubber modified polypropylene

  17. Toughened carbon fibre fabric-reinforced thermoplastic composites

    OpenAIRE

    Abt, Tobias Martin; Sánchez Soto, Miguel; Maspoch Rulduà, Mª Lluïsa; Velasco Perero, José Ignacio

    2014-01-01

    Toughened carbon fibre fabric-reinforced composites were obtained by compression moulding of powder prepregs, using a modified cyclic butylene terephthalate (pCBT) matrix and a bi-directional [0°/90°] carbon fibre fabric. Modification of the pCBT matrix was done by adding small amounts of epoxy resin or isocyanates, acting as toughening agents. Homogeneous CBT/epoxy and CBT/isocyanate blends were obtained by melt blending in a lab-scale batch mixer by applying low temperatures and short proce...

  18. Toughening and strengthening mechanism of zirconia-alumina multiphase ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yu, M.Q.; Fan, S.G. [Research Inst. of Synthetic Crystals, Beijing, BJ (China); Shen, Q.; Zhang, L.M. [Wuhan Univ. of Technology (China)

    2003-07-01

    In the present study, the effect of compositions on the mechanical properties of zirconia-alumina multiphase ceramics was studied. The results showed that with the variety of ZrO{sub 2} content, the change of bending strength and fracture toughness of the multiphase ceramics exhibited a saddle shape which could be divided into three zones: ZTA, ADZ, and Transition zone. The mechanism of toughening and strengthening in each zone was mainly analyzed, and it was found that stress-induced transformation toughening of ZrO{sub 2} and dispersion strengthening of Al{sub 2}O{sub 3} were the two main factors. (orig.)

  19. Toughening of PMR composites by gradient semi-interpenetrating networks

    Science.gov (United States)

    Johnston, N. J.; Srinivasan, K.; Peter, R. H.

    1992-01-01

    The toughening of the PMR-15 and LARC RP-46 high temperature thermosetting polyimides is presently attempted through the construction of a semiinterpenetrating network at ply interfaces through the use of the Matrimid 5218 thermoplastic polyimide powder, whose 315-320 glass transition temperature is compatible with the PMR matrices. The 60 vol pct fiber composites thus prepared for the two resins, with and without toughening, were comprehensively characterized in flexure, tension, intralaminar and short beam shear, compression and quasi-isotropic short-block compression, as well as modes I and II interlaminar fracture toughness and compression after impact.

  20. Influence of Matrixes on Microstructure and Properties of CTBN Toughened Epoxy Resins

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The influence of the type of epoxy resins (E-51, F-51) on the mechanical properties and microstructure of carboxyl-terminated butadiene nitrile rubber (CTBN) toughened epoxy resins was investigated by determination of adhesive strength and toughness as well as observation of scanning electron microstructure (SEM). The results indicate that the adhesive strength of CTBN toughened E-51 system is superior to CTBN toughened F-51 system. However, CTBN toughened E-51 system is inferior to CTBN toughened F-51 system in the toughness. This difference is related to the microstructure of two toughened systems. For CTBN toughened F-51, larger cavities and rubber particles are found in the system. The larger cavities easily cause stress concentration and result in decrease of the adhesive strength. While the larger rubber particles may better terminate the development of crazing and shear banding and result in increase of the toughness.

  1. MN Dra - a SU UMa-type star during its September 2013 superoutburst

    CERN Document Server

    Bakowska, Karolina; Pospieszynski, Remigiusz

    2016-01-01

    We report CCD photometry of the cataclysmic variable star MN Draconis. During the season of August-September 2013, one normal outburst and one superoutburst were detected. In the light curves of MN Dra clear superhumps were present during September 2013 superoutburst. That fact confirms that the star is a member of SU UMa class.

  2. A Stringy (Holographic) Pomeron with Extrinsic Curvature

    CERN Document Server

    Qian, Yachao

    2014-01-01

    We model the soft pomeron in QCD using a scalar Polyakov string with extrinsic curvature in the bottom-up approach of holographic QCD. The overall dipole-dipole scattering amplitude in the soft pomeron kinematics is shown to be sensitive to the extrinsic curvature of the string for finite momentum transfer. The characteristics of the diffractive peak in the differential elastic $pp$ scattering are affected by a small extrinsic curvature of the string.

  3. Diversity of equine major histocompatiblity complex class II DRA locus in Posavina and Croatian Coldblood horse: a new polymorphism detected

    Directory of Open Access Journals (Sweden)

    Ino Curik

    2010-01-01

    Full Text Available Domestic equidae display polymorphism within ELA-DRA locus which is not characteristic for other species. We characterised sequence polymorphism present at ELADRA locus exon 2 and estimated allele frequencies in two autochthonous breeds, Posavina and Croatian Coldblood. In 88 horses, four different alleles were found, one of them not reported before in horses. The new allele shows non-synonymous mutation at position 65 (T→A causing amino acid change (Phe→Tyr in antigen binding site and synonymous mutation at position 105 (C→T. Our findings emphasize the importance of DRA polymorphism among equids and some specific DRA frequency pattern potentially specific in draught horses.

  4. Velocity Curve Analysis of the Spectroscopic Binary Stars NSV 223, AB And, V2082 Cyg, HS Her, V918 Her, BV Dra, BW Dra, V2357 Oph, and YZ Cas by the Non-linear Least Squares

    CERN Document Server

    Karami, K; Soltanzadeh, M M

    2008-01-01

    Using measured radial velocity data of nine double lined spectroscopic binary systems NSV 223, AB And, V2082 Cyg, HS Her, V918 Her, BV Dra, BW Dra, V2357 Oph, and YZ Cas, we find corresponding orbital and spectroscopic elements via the method introduced by Karami & Mohebi (2007a) and Karami & Teimoorinia (2007). Our numerical results are in good agreement with those obtained by others using more traditional methods.

  5. Dražeslavov zapis o Gradu: Dubrovnik u djelima Ive Andrića

    Directory of Open Access Journals (Sweden)

    Mario Šimudvarac

    2017-05-01

    Full Text Available This article discusses the works of Ivo Andrićin which Dubrovnik and its citizens are described. They include his short storiesPredvečernji čas (The Early Evening Hour, Dva zapisa bosanskog pisara Dražeslava(Two Accounts of the Bosnian Scribe Dražeslav, Susret (The Meeting and Dubrovačka vejavica (Dubrovnik’s Whirlwind. Also examined are two of his texts: San o gradu(A Dream about the City and a foreword to the book Nekrolog jednoj čaršiji (Necrology to a Bazaar by Zulfikar Zuko Džumhur. The mentioned works are interpreted from the viewpoint of Andrić’s overall poetics, as well as from the imagological and spatial perspective.

  6. Analysis of the strengthening and toughening of a biomaterial interface

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on the transmission electron micrographs of nacre, the existence of mineral bridges in the organic matrix interface is confirmed. It is proposed that the microarchitecture of nacre should be considered as a “brick-bridge-mortar” (BBM) arrangement rather than traditional “brick and mortar” (BM) one. Experiments and analyses indicate that the mineral bridges effectively affect the strength and toughness of the interfaces in nacre. Comparison with a laminated composite with BM structure, SiC/BN, shows that the pattern of the crack extension and the toughening mechanism of the two materials are different. This reveals that the mineral bridges play a key role in the toughening mechanisms of nacre, which gives a conceptual guidance in material synthesis.

  7. Feasibility of Using Multilayer Platelets as Toughening Agents

    Directory of Open Access Journals (Sweden)

    Yuan-Liang Chin

    2009-12-01

    Full Text Available It is known that the toughness of brittle ceramics can be improved significantly with the addition of hard platelets. In the present study, platelet-shape multilayer ceramic laminates are utilized as a toughening agent for alumina ceramics. They are prepared by laminating the BaTiO3-based ceramic tapes. Although the elastic modulus of the BaTiO3-based platelets is lower than that of the alumina matrix, and the platelets are also reactive to alumina at elevated temperatures, the weak platelets are found to exhibit the ability to deflect major matrix cracks by forming a large number of microcrack branches within the platelets, thus achieving the desired toughening effect.

  8. Development of ricehusk ash reinforced bismaleimide toughened epoxy nanocomposites.

    Science.gov (United States)

    K, Kanimozhi; Sethuraman, K.; V, Selvaraj; Alagar, Muthukaruppan

    2014-09-01

    Abstract Recent past decades have witnessed remarkable advances in composites with potential applications in biomedical devices, aerospace, textiles, civil engineering, energy, electronic engineering, and household products. Thermoset polymer composites have further enhanced and broadened the area of applications of composites. In the present work epoxy-BMI toughened-silica hybrid (RHA/DGEBA-BMI) was prepared using bismaleimide as toughener, bisphenol-A as matrix and a silica precursor derived from rice husk ash as reinforcement with glycidoxypropyltrimethoxysilane as coupling agent. Differential scanning calorimetry, electron microscopy, thermogravimetric analysis, and goniometry were used to characterize RHA/DGEBA-BMI composites developed in the present work. Tensile, impact and flexural strength, tensile and flexural modulus, hardness, dielectric properties were also studied and discussed. The hybrid nanocomposites possess the higher values of the glass transition temperature (Tg) and mechanical properties than those of neat epoxy matrix.

  9. Toughening Mechanisms in Silica-Filled Epoxy Nanocomposites

    Science.gov (United States)

    Patel, Binay S.

    Epoxies are widely used as underfill resins throughout the microelectronics industry to mechanically couple and protect various components of flip-chip assemblies. Generally rigid materials largely surround underfill resins. Improving the mechanical and thermal properties of epoxy resins to better match those of their rigid counterparts can help extend the service lifetime of flip-chip assemblies. Recently, researchers have demonstrated that silica nanoparticles are effective toughening agents for lightly-crosslinked epoxies. Improvements in the fracture toughness of silica-filled epoxy nanocomposites have primarily been attributed to two toughening mechanisms: particle debonding with subsequent void growth and matrix shear banding. Various attempts have been made to model the contribution of these toughening mechanisms to the overall fracture energy observed in silica-filled epoxy nanocomposites. However, disparities still exist between experimental and modeled fracture energy results. In this dissertation, the thermal, rheological and mechanical behavior of eight different types of silica-filled epoxy nanocomposites was investigated. Each nanocomposite consisted of up to 10 vol% of silica nanoparticles with particle sizes ranging from 20 nm to 200 nm, with a variety of surface treatments and particle structures. Fractographical analysis was conducted with new experimental approaches in order to accurately identify morphological evidence for each proposed toughening mechanism. Overall, three major insights into the fracture behavior of real world silica-filled epoxy nanocomposites were established. First, microcracking was observed as an essential toughening mechanism in silica-filled epoxy nanocomposites. Microcracking was observed on the surface and subsurface of fractured samples in each type of silica-filled epoxy nanocomposite. The additional toughening contribution of microcracking to overall fracture energy yielded excellent agreement between experimental

  10. TOUGHENING OF FERROELECTRICS BY THE OUT-OF-PLANE POLING

    Institute of Scientific and Technical Information of China (English)

    杨卫; 方菲

    2003-01-01

    Subjected to the prior out-of-plane poling, the ferroelectrics can be toughened considerably. The present paper describes the variation of the stress intensity factor (SIF) by 90° switching in ferroelectrics. The analysis is carried out for the combined mechanical and electrical loading, with simple relations obtained for the case of the purely electrical loading. The out-of-plane poling is found to raise the SIF for the crack initiation, but appreciably reduces the SIF for the crack growth in a steady state. More stable fracture resistance curves can be achieved by the out-of-plane poling. This prediction is supported quantitatively by the testing data of SENB specimens of PZT-5 samples, when the toughening effects of polings in three orthogonal directions are compared.

  11. ESPACIOS CONTEMPORÁNEOS PARA LA UTOPÍA - Entrevista a la Dra. Vita Fortunati

    Directory of Open Access Journals (Sweden)

    Lucas E. Misseri

    2010-04-01

    Full Text Available Entrevista a la Dra. Vita FortunatiUniBo – ItaliaDoctora en literatura y profesora de literatura inglesa en laUniversidad de Bolonia, Italia. Se ha especializado en latemática del utopismo a la cual ha contribuido con creces. En1989 fundó el Centro interdepartamental de estudios sobre lautopía en la mencionada universidad.

  12. [Application analysis of adverse drug reaction terminology WHOART and MedDRA].

    Science.gov (United States)

    Liu, Jing; Xie, Yan-ming; Gai, Guo-zhong; Liao, Xing

    2015-12-01

    Drug safety has always been a global focus. Discovery and accurate information acquisition of adverse drug reaction have been the most crucial concern. Terminology of adverse drug reaction makes adverse reaction medical report meaningful, standardized and accurate. This paper discussed the domestic use of the terminology WHOART and MedDRA in terms of content, structure, and application situation. It also analysed the differences between the two terminologies and discusses the future trend of application in our country

  13. Toughening mechanism in elastomer-modified epoxy resins, part 2

    Science.gov (United States)

    Yee, A. F.; Pearson, R. A.

    1984-01-01

    The role of matrix ductility on the toughenability and toughening mechanism of elastomer-modified DGEBRA epoxies was investigated. Matrix ductility was varied by using epoxide resins of varying epoxide monomer molecular weights. These epoxide resins were cured using 4,4' diaminodiphenyl sulfone (DDS) and, in some cases, modified with 10% HYCAR(r)CTBN 1300X8. Fracture roughness values for the neat epoxies were found to be almost independent on the monomer molecular weight of the epoxide resin used. However, it was found that the fracture toughness of the elastomer-modified epoxies was very dependent upon the epoxide monomer molecular weight. Tensile dilatometry indicated that the toughening mechanism, when present, is similar to the mechanisms found for the piperidine cured epoxies in Part 1. SEM and OM corroborate this finding. Dynamic mechanical studies were conducted to shed light on the toughenability of the epoxies. The time-dependent small strain behavior of these epoxies were separated into their bulk and shear components. The bulk component is related to brittle fracture, whereas the shear component is related to yielding. It can be shown that the rates of shear and bulk strain energy buildup for a given stress are uniquely determined by the values of Poisson's ratio, nu. It was found that nu increases as the monomer molecular weight of the epoxide resin used increases. This increase in nu can be associated with the low temperature beta relaxation. The effect of increasing cross-link density is to shift the beta relaxation to higher temperatures and to decrease the magnitude of the beta relaxation. Thus, increasing cross-link density decreases nu and increases the tendency towards brittle fracture.

  14. Rubber-toughening of dimethacrylate dental composite resin.

    Science.gov (United States)

    Lee, Valerie A; Cardenas, H Lee; Rawls, H Ralph

    2010-08-01

    Dimethacrylate dental composite resins exhibit inherently low toughness. Toughening of these materials may reduce the incidence of marginal and bulk fracture of composite restorations. To determine if dimethacrylate dental restorative materials can be rubber-toughened, and if so, to identify a possible mechanism. A filler composed of aggregates of polybutadiene/silica as well as irregularly-shaped silica slabs was produced by mixing silica with polybutadiene in dichloromethane. The dried filler was subsequently ground and sieved to composition of the complex filler. Filler was added to a bis-GMA/bis-EMA/TEGDMA resin system and fractured in three-point bend test mode at a crosshead speed of 1 mm/min. In addition, 1 bar was fractured at a crosshead speed of 0.001 mm/min to identify a possible mechanism for toughening. In specimens fractured at 1 mm/min, flexural modulus is increased or maintained and flexural strength and energy to break increase as the amount of polybutadiene in the aggregates increases. Cavitation of high-rubber-containing aggregates is demonstrated. In the one specimen fractured at 0.001 mm/min, a marked increase in size of high-rubber-containing aggregates along with severe shear damage in the surrounding matrix is shown, suggesting that cavitation with subsequent absorption of energy during shear yielding is the likely mechanism behind the increase in energy to break in bars fractured at 1 mm/min. These results indicate that dimethacrylate dental composite materials can be rubber toughened, which may potentially reduce marginal and bulk fractures of composite restorations, and consequently extend their service lifetime.

  15. The toughening mechanism of rubber particles in polypropylene composite

    Science.gov (United States)

    Shi, L.; Xiao, J. M.

    2017-01-01

    Filling polypropylene materials with rubber particles can effectively increase the toughness of PP material and improve its cushioning properties. In this paper, we used the two kinds of method of the finite element analysis and experiment to study the rubber particles toughening mechanism, got the deformation process of particles when polypropylene material compressed and the yield stress of polypropylene after compression with particles filled or not.

  16. Atmospheric lithium abundances of the carbon giants AQ And, HK Lyr, UX Dra, and WZ Cas

    Science.gov (United States)

    Yakovina, L. A.; Pavlenko, Ya. V.

    2012-01-01

    The LTE lithium abundances, log N (Li), have been determined for the atmospheres of the four carbon giants AQ And, HK Lyr, UX Dra, and WZ Cas, applying the synthetic-spectrum technique to the LiI λ670.8 nm resonance doublet. We used estimates of the effective temperatures T eff, metallicities, elemental abundances, and carbon-isotope ratios for these stars from the literature [12C/13C]. The resulting lithium abundances depend significantly on the adopted T eff, so that we can find each star's range of possible log N(Li) values for a given range of effective temperatures (Δ T eff = 200-300 K). The uncertainty in the derived log N(Li) values is 1.3 for AQ And and UX Dra, 0.5 for HK Lyr, and 0.8 for WZ Cas. Our most probable log N(Li) values (or ranges) are -1.25 for AQ And, -1.2 for HK Lyr, -1.0 ≤ log N(Li) ≤ +0.3 for UX Dra, and 4.3 ≤ log N(Li) ≤ 4.8 for WZ Cas. The derived C/O ratios for the stellar atmospheres also depend on T eff. Possible uncertainties in other atmospheric parameters do not change log N(Li) by more than 0.2.

  17. Korean BAC library construction and characterization of HLA-DRA, HLA-DRB3.

    Science.gov (United States)

    Park, Mi-Hyun; Lee, Hye-Ja; Bok, Jeong; Kim, Cheol-Hwan; Hong, Seong-Tshool; Park, Chan; Kimm, KuChan; Oh, Bermseok; Lee, Jong-Young

    2006-07-31

    A human bacterial artificial chromosome (BAC) library was constructed with high molecular weight DNA extracted from the blood of a male Korean. This Korean BAC library contains 100,224 clones of insert size ranging from 70 to 150 kb, with an average size of 86 kb, corresponding to a 2.9-fold redundancy of the genome. The average insert size was determined from 288 randomly selected BAC clones that were well distributed among all the chromosomes. We developed a pooling system and three-step PCR screen for the Korean BAC library to isolate desired BAC clones, and we confirmed its utility using primer pairs designed for one of the clones. The Korean BAC library and screening pools will allow PCR-based screening of the Korean genome for any gene of interest. We also determined the allele types of HLA-DRA and HLA-DRB3 of clone KB55453, located in the HLA class II region on chromosome 6p21.3. The HLA-DRA and DRB3 genes in this clone were identified as the DRA*010202 and DRB3*01010201 types, respectively. The haplotype found in this library will provide useful information in future human disease studies.

  18. Topological Toughening of graphene and other 2D materials

    Science.gov (United States)

    Gao, Huajian

    It has been claimed that graphene, with the elastic modulus of 1TPa and theoretical strength as high as 130 GPa, is the strongest material. However, from an engineering point of view, it is the fracture toughness that determines the actual strength of materials, as crack-like flaws (i.e., cracks, holes, notches, corners, etc.) are inevitable in the design, fabrication, and operation of practical devices and systems. Recently, it has been demonstrated that graphene has very low fracture toughness, in fact close to that of ideally brittle solids. These findings have raised sharp questions and are calling for efforts to explore effective methods to toughen graphene. Recently, we have been exploring the potential use of topological effects to enhance the fracture toughness of graphene. For example, it has been shown that a sinusoidal graphene containing periodically distributed disclination quadrupoles can achieve a mode I fracture toughness nearly twice that of pristine graphene. Here we report working progresses on further studies of topological toughening of graphene and other 2D materials. A phase field crystal method is adopted to generate the atomic coordinates of material with specific topological patterns. We then perform molecular dynamics simulations of fracture in the designed samples, and observe a variety of toughening mechanisms, including crack tip blunting, crack trapping, ligament bridging, crack deflection and daughter crack initiation and coalescence.

  19. Fitness, Extrinsic Complexity and Informing Science

    Directory of Open Access Journals (Sweden)

    Grandon Gill

    2017-03-01

    We raise concerns about society’s continuing investment in academic research that discounts the extrinsic complexity of the domains under study. Future Research We highlight a need for research to operationalize the concepts of fitness and complexity in practice.

  20. From optimization to dielectric resonator antenna (DRA) application of YIG: Synthesis approach

    Energy Technology Data Exchange (ETDEWEB)

    Wan Ali, Wan Fahmin Faiz [Structural Materials Niche Area, School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang (Malaysia); Othman, Mohamadariff; Ain, Mohd Fadzil [School of Electrical and Electronics Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang (Malaysia); Abdullah, Norazharuddin Shah [Structural Materials Niche Area, School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang (Malaysia); Ahmad, Zainal Arifin, E-mail: srzainal@usm.my [Structural Materials Niche Area, School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang (Malaysia)

    2015-10-05

    Highlights: • 99.2% of the YIG purity was optimized using ANOVA-statistical approach. • The optimized YIG has shown a strong frequency resonant at 12.501 GHz. • Less than 1% error indicated the optimized YIG is suitable to be used as a DRA. • A stable radiation pattern of optimized YIG was also observed stable. - Abstract: The efficacy of yttrium iron garnet (YIG) as magneto-dielectric ceramic, depends heavily on its purity. The presence of undesirable phase(s) such as yttrium iron perovskite (YIP) has led to performance deterioration, which is critical especially in wireless communication devices. This work presents the use of an ANOVA-statistical approach to improve and optimize the YIG’s purity. Effects of particle sizes (5, 50 and 100 μm), reactant concentration (excess Fe{sub 2}O{sub 3} in standard YIG formulation – 0, 10, and 20 wt%), and formation temperatures (1150, 1200, and 1250 °C), on the purity of YIG were investigated. The results indicated that the obtained statistical model adequately represented the experimental data, as reflected in the 3D contour plot. It was also discovered that the concentration of Fe{sub 2}O{sub 3} reactant (up to 8 wt%) and formation temperature (1240 °C), significantly affects the formation of high-purity YIG while variation of the reactant’s particle sizes is seen insignificant. Finally, a possible application of the optimized YIG (OPYIG) in dielectric resonator antenna (DRA) application is demonstrated. It was found that OPYIG was resonating at 12.50 GHz with a stable and bi-directional radiation pattern. This optimization process is successfully produced 99.2% YIG and could be suitable for DRA application.

  1. Toughening of PMR composites by semi-interpenetrating networks

    Science.gov (United States)

    Tiwari, S. N.; Srinivansan, K.

    1991-01-01

    Polymerization of monomer reactants (PMR-15) type polyimide and RP46 prepregs were drum wound using IM-7 fibers. Prepregging and processing conditions were optimized to yield good quality laminates with fiber volume fractions of 60 percent (+/- 2 percent). Samples were fabricated and tested to determine comprehensive engineering properties of both systems. These included 0 deg flexure, short beam shear, transverse flexure and tension, 0 deg tension and compression, intralaminar shear, short block compression, mode 1 and 2 fracture toughness, and compression after impact properties. Semi-2-IPN (interpenetrating polymer networks) toughened PMR-15 and RP46 laminates were also fabricated and tested for the same properties.

  2. Addition of platinum and silver nanoparticles to toughen dental porcelain.

    Science.gov (United States)

    Fujieda, Tokushi; Uno, Mitsunori; Ishigami, Hajime; Kurachi, Masakazu; Wakamatsu, Nobukazu; Doi, Yutaka

    2012-01-01

    Several studies have investigated toughening porcelain that is layered over a frame or a core. The introduction of residual compressive stress to the surface of porcelain has been shown to be effective to strengthen it. In the present study, nanoparticles of precious metals of silver and platinum (rather than non-precious metals) were used to evaluate if they could increase the fracture resistance of porcelain. The addition of silver and platinum nanoparticles was found to improve the mechanical properties of porcelain since it increased both the Young's modulus and the fracture toughness of commercial porcelain.

  3. Brittle-tough transitions during crack growth in toughened adhesives

    Science.gov (United States)

    Thoules, Michael

    2008-03-01

    The use of structural adhesives in automotive applications relies on an effective understanding of their performance under crash conditions. In particular, there is considerable potential for mechanics-based modeling of the interaction between an adhesive layer and the adherends, to replace current empirical approaches to design. Since energy dissipation during a crash, mediated by plastic deformation of the structure, is a primary consideration for automotive applications, traditional approaches of fracture mechanics are not appropriate. Cohesive-zone models that use two fracture parameters - cohesive strength and toughness - have been shown to provide a method for quantitative mechanics analysis. Combined numerical and experimental techniques have been developed to deduce the toughness and strength parameters of adhesive layers, allowing qualitative modeling of the performance of adhesive joints. These techniques have been used to study the failure of joints, formed from a toughened adhesive and sheet metal, over a wide range of loading rates. Two fracture modes are observed: quasi-static crack growth and dynamic crack growth. The quasi-static crack growth is associated with a toughened mode of failure; the dynamic crack growth is associated with a more brittle mode of failure. The results of the experiments and analyses indicate that the fracture parameters for quasi-static crack growth in this toughened system are essentially rate independent, and that quasi-static crack growth can occur even at the highest crack velocities. Effects of rate appear to be limited to the ease with which a transition to dynamic fracture could be triggered. This transition appears to be stochastic in nature, and it does not appear to be associated with the attainment of any critical value for crack velocity or loading rate. Fracture-mechanics models exist in the literature for brittle-ductile transitions in rate-dependent polymers, which rely on rate dependent values of toughness

  4. Supply chain management in Forest products industry-case study for S?dra Cell Company

    Institute of Scientific and Technical Information of China (English)

    YAO; PAN

    2016-01-01

    The supply chain plays an increasing significant role in current global business operation process.It is not just considered as a crucial factor for leading the company to achieve their strategic goals,but also assisting firm’s to enhance the competitiveness in its own industry.This report choses the Swedish forest company-S?dra Cell as a case company to analysis its supply chain management advantages and disadvantages. It also states the role of supply chain management theory in assisting organization to achieve its strategic goal and marketing strategies.

  5. Toughening and its association with the postharvest quality of king oyster mushroom (Pleurotus eryngii) stored at low temperature.

    Science.gov (United States)

    Li, Danqing; Qin, Xiaoyi; Tian, Pingping; Wang, Jie

    2016-04-01

    Toughening-induced textural decay easily occurs in stored mushrooms. The objective of this study was to investigate the textural alteration caused by toughening in relation to other quality attributes of king oyster mushroom (Pleurotus eryngii). Fresh king oyster mushrooms, packed in low-density polyethylene bags, were stored at different low temperatures for 18 days to measure textural and other quality attributes. It was found that toughening occurred twice during the entire storage time. Highly associated change profiles were observed for the lignin content and activities of three important enzymes involved in lignin synthesis. The chitin and cellulose contents exhibited low correlation with toughening. Malondialdehyde content, electrolyte leakage rate and total phenolics content appeared to be related to toughening, but the browning index showed a negative correlation with toughening. Our results suggested that toughening may be mainly caused by lignification and can affect the postharvest quality of the tested mushrooms.

  6. Toughening mechanism in elastometer-modified epoxy resins: Part 1

    Science.gov (United States)

    Yee, A. F.; Pearson, R. A.

    1983-01-01

    Several plaques of Epon 828, cured with piperidine, modified with hycar(r) CTBN 1300X8, Hycar(R) CTBN 1300X13, and Hycar(R) CTBN 1300x15, and in some cases modified with biphenol A (BPA), yielded properly toughened epoxies with rubber particle diameters ranging from 0.1 to 10 microns. Fracture toughness experiments indicate that toughness was more a function of rubber content than the rubber particle size. Tensile volumetric behavior of the near resin exhibits two regions: an initial region where the increase in volume strain was due to the Poisson's effect, and a second region where a slower rate of increase in volume strain was due to shear deformation. Tensile volumetric deformation of an elastomer-modified epoxy exhibits the same type of behavior to that of the neat resin at low rates ( 3.2x0.01 sec(-1)). But at very high strain rates, which correspond more closely to the strain rates at the crack tip, there exists an increase in volume strain beyond the Poisson's effect. TEM, SEM and OM studies indicate that the rubber particles had voided. When a thin section from the deformed region is viewed under crossed-polarized light, shear bands are seen connecting voided rubber particles. From this information cavitation and enhanced shear band formation is proposed as the toughening mechanism.

  7. Power Requirements for The NASA Mars Design Reference Architecture (DRA) 5.0

    Science.gov (United States)

    Cataldo, Robert L.

    2009-01-01

    This paper summarizes the power systems analysis results from NASA s recent Mars DRA 5.0 study which examined three architecture options and resulting mission requirements for a human Mars landing mission in the post-2030 timeframe. DRA 5.0 features a long approximately 500 day surface stay split mission using separate cargo and crewed Mars transfer vehicles. Two cargo flights, utilizing minimum energy trajectories, pre-deploy a cargo lander to the surface and a habitat lander into a 24-hour elliptical Mars parking orbit where it remains until the arrival of the crew during the next mission opportunity approximately 26 months later. The pre-deployment of cargo poses unique challenges for set-up and emplacement of surface assets that results in the need for self or robotically deployed designs. Three surface architecture options were evaluated for breadth of science content, extent of exploration range/capability and variations in system concepts and technology. This paper describes the power requirements for the surface operations of the three mission options, power system analyses including discussion of the nuclear fission, solar photovoltaic and radioisotope concepts for main base power and long range mobility.

  8. VizieR Online Data Catalog: BVR photometry of IZ Mon and AR Dra (Yang+, 2016)

    Science.gov (United States)

    Yang, Y.-G.; Dai, H.-F.; Zhou, Z.; Li, Q.

    2016-07-01

    CCD Photometry for IZ Mon and AR Dra, was acquired using the 60cm telescope and the 85cm telescope at the Xinglong station (XLs) of National Astronomical Observatories of China (NAOC). Two telescopes are equipped with the standard Johnson-Cousins UBVRcIc. filters. We then obtained the individual observations as heliocentric Julian dates and differential magnitude, which are listed in Table1. The complete light curves for IZ Mon were obtained on 2009 January 20, 22, 24, 25, and 26, and March 1, using the 85cm telescope. The exposure times are fixed to be 20, 15, and 15s for BVR bands, respectively. A total of 961, 960, and 959 effective images in BVR bands are obtained. Another primary eclipse for IZ Mon was monitored on 2011 January 17. AR Dra was observed on 2009 February 20, 25, 26, and 27, with the 65cm telescope. The typical exposure times are 50, 40 and 40s for BVR bands, which depend on the condition of weather. In total, we obtained 733, 728 and 356 images in B, V and R bands, respectively. (6 data files).

  9. Extrinsic curvature induced 2-d gravity

    CERN Document Server

    Viswanathan, K S

    1993-01-01

    Abtract: 2-dimensional fermions are coupled to extrinsic geometry of a conformally immersed surface in ${\\bf R}^3$ through gauge coupling. By integrating out the fermions, we obtain a WZNW action involving extrinsic curvature of the surface. Restricting the resulting effective action to surfaces of $h\\sqrt g=1$, an explicit form of the action invariant under Virasaro symmetry is obtained. This action is a sum of the geometric action for the Virasaro group and the light-cone action of 2-d gravity plus an interaction term. The central charges of the theory in both the left and right sectors are calculated.

  10. Technological advances in the study of HLA-DRA promoter regulation: Extending the functions of CIITA, Oct-1, Rb, and RFX

    Institute of Scientific and Technical Information of China (English)

    Melissa I.Niesen; Aaron R.Osborne; William R.Lagor; Harry Zhang; Kristy Kazemfar; Gene C.Ness; George Blanck

    2009-01-01

    Several advances were established in examining the interaction of transcriptional factors with the HLA-DRA promoter. First, hydrodynamic injection was used to demonstrate the activation of the promoter by class II transactivator in a live mouse. Second, the Oct-1 DNA-binding site in the HLA-DRA promoter is a negative element in many cells, but here we show that Oct-1 activates the promoter independently of the Oct-1-binding site. Third, the retinoblastoma (Rb) protein is required for the induction of the endogenous HLA-DRA gene, due to a poorly understood, pleiotropic effect on the Oct-1 and YY1 repressive functions at the HLA-DRA promoter. There has never been an indication that direct promoter activation, by Rb, is possible. Here, we report that the first HLA-DRA intron has an Rb-responsive element, as indicated by a transient transfection/promoter reporter assay. Finally, RFX activates a methylated version of an HLA-DRA promoter reporter construct, consistent with the role of RFX in rescuing the expression of the methylated, endogenous HLA-DRA gene. Here, we report that this RFX function is not limited to a specific RFX-binding sequence or to the HLA-DRA promoter. These advances provide bases for novel investigations into the function of the major histocompatibility class II promoter.

  11. Intrinsic and Extrinsic Motivation among Collegiate Instrumentalists

    Science.gov (United States)

    Diaz, Frank M.

    2010-01-01

    The purpose of this study was to gather and compare information on measures of intrinsic and extrinsic motivation among instrumentalists enrolled in collegiate ensembles. A survey instrument was developed to gather information concerning demographic data and responses to questions on motivational preference. Participants were undergraduate and…

  12. Intrinsic and Extrinsic Motivation among Collegiate Instrumentalists

    Science.gov (United States)

    Diaz, Frank M.

    2010-01-01

    The purpose of this study was to gather and compare information on measures of intrinsic and extrinsic motivation among instrumentalists enrolled in collegiate ensembles. A survey instrument was developed to gather information concerning demographic data and responses to questions on motivational preference. Participants were undergraduate and…

  13. Encouraging Classroom Participation with Empty Extrinsic Rewards

    Science.gov (United States)

    Guinee, William

    2012-01-01

    In this article, the author talks about how to encourage classroom participation with empty extrinsic rewards. He uses "bonus points" in awarding students for particularly interesting or well thought-out contributions to the class discussion. These bonus points have absolutely no effect on the student's course grade. But the students respond…

  14. DRA/NASA/ONERA Collaboration on Icing Research. Part 2; Prediction of Airfoil Ice Accretion

    Science.gov (United States)

    Wright, William B.; Gent, R. W.; Guffond, Didier

    1997-01-01

    This report presents results from a joint study by DRA, NASA, and ONERA for the purpose of comparing, improving, and validating the aircraft icing computer codes developed by each agency. These codes are of three kinds: (1) water droplet trajectory prediction, (2) ice accretion modeling, and (3) transient electrothermal deicer analysis. In this joint study, the agencies compared their code predictions with each other and with experimental results. These comparison exercises were published in three technical reports, each with joint authorship. DRA published and had first authorship of Part 1 - Droplet Trajectory Calculations, NASA of Part 2 - Ice Accretion Prediction, and ONERA of Part 3 - Electrothermal Deicer Analysis. The results cover work done during the period from August 1986 to late 1991. As a result, all of the information in this report is dated. Where necessary, current information is provided to show the direction of current research. In this present report on ice accretion, each agency predicted ice shapes on two dimensional airfoils under icing conditions for which experimental ice shapes were available. In general, all three codes did a reasonable job of predicting the measured ice shapes. For any given experimental condition, one of the three codes predicted the general ice features (i.e., shape, impingement limits, mass of ice) somewhat better than did the other two. However, no single code consistently did better than the other two over the full range of conditions examined, which included rime, mixed, and glaze ice conditions. In several of the cases, DRA showed that the user's knowledge of icing can significantly improve the accuracy of the code prediction. Rime ice predictions were reasonably accurate and consistent among the codes, because droplets freeze on impact and the freezing model is simple. Glaze ice predictions were less accurate and less consistent among the codes, because the freezing model is more complex and is critically

  15. Adaptive molecular evolution of the Major Histocompatibility Complex genes, DRA and DQA, in the genus Equus

    Directory of Open Access Journals (Sweden)

    Getz Wayne M

    2011-05-01

    Full Text Available Abstract Background Major Histocompatibility Complex (MHC genes are central to vertebrate immune response and are believed to be under balancing selection by pathogens. This hypothesis has been supported by observations of extremely high polymorphism, elevated nonsynonymous to synonymous base pair substitution rates and trans-species polymorphisms at these loci. In equids, the organization and variability of this gene family has been described, however the full extent of diversity and selection is unknown. As selection is not expected to act uniformly on a functional gene, maximum likelihood codon-based models of selection that allow heterogeneity in selection across codon positions can be valuable for examining MHC gene evolution and the molecular basis for species adaptations. Results We investigated the evolution of two class II MHC genes of the Equine Lymphocyte Antigen (ELA, DRA and DQA, in the genus Equus with the addition of novel alleles identified in plains zebra (E. quagga, formerly E. burchelli. We found that both genes exhibited a high degree of polymorphism and inter-specific sharing of allele lineages. To our knowledge, DRA allelic diversity was discovered to be higher than has ever been observed in vertebrates. Evidence was also found to support a duplication of the DQA locus. Selection analyses, evaluated in terms of relative rates of nonsynonymous to synonymous mutations (dN/dS averaged over the gene region, indicated that the majority of codon sites were conserved and under purifying selection (dN dS. However, the most likely evolutionary codon models allowed for variable rates of selection across codon sites at both loci and, at the DQA, supported the hypothesis of positive selection acting on specific sites. Conclusions Observations of elevated genetic diversity and trans-species polymorphisms supported the conclusion that balancing selection may be acting on these loci. Furthermore, at the DQA, positive selection was

  16. Intrinsic and extrinsic factors influencing large African herbivore movements

    NARCIS (Netherlands)

    Venter, J.A.; Prins, H.H.T.; Mashanova, A.; Boer, de W.F.; Slotow, R.

    2015-01-01

    Understanding environmental as well as anthropogenic factors that influence large herbivore ecological patterns and processes should underpin their conservation and management. We assessed the influence of intrinsic, extrinsic environmental and extrinsic anthropogenic factors on movement behaviour o

  17. Effects of Extrinsic Rewards on Intrinsic Motivation in the Classroom.

    Science.gov (United States)

    Workman, Edward A.; Williams, Robert L.

    1980-01-01

    Reviews classroom behavior management studies to see if extrinsic rewards affect intrinsic reinforcement value of appropriate classroom behaviors. Conclusion indicates extrinsic rewards are useful. Teachers need not avoid the use of rewards in fear of undermining intrinsic interest. (LAB)

  18. Effects of Extrinsic Rewards on Intrinsic Motivation in the Classroom.

    Science.gov (United States)

    Workman, Edward A.; Williams, Robert L.

    1980-01-01

    Reviews classroom behavior management studies to see if extrinsic rewards affect intrinsic reinforcement value of appropriate classroom behaviors. Conclusion indicates extrinsic rewards are useful. Teachers need not avoid the use of rewards in fear of undermining intrinsic interest. (LAB)

  19. Characterization of the Residual Stress State in Commercially Fully Toughened Glass

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes; Stang, Henrik

    2010-01-01

    Toughened glass is often used in load carrying elements due to the relatively high tensile strength compared with float glass. The apparent tensile strength of toughened glass is a combination of the pure material strength and the residual stresses imposed by the toughening process. This paper...... is concerned with an experimental characterization of the residual stress state for toughened glass. Results for the variation of residual stresses within 32 square specimens with a side length of 300 mm are investigated. The specimens varied in thickness and one group was glass with low iron content....... The photoelastic constant was estimated from a four-point bending test. The experimental results revealed large variations in the residual stress state within each specimen and between groups of different thicknesses. The results are compared with a nonstandard fragmentation test, showing that the fragment size...

  20. Enhanced Damage Tolerance High Temperature Composite Using a Biomimetic Toughening System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Lightweight composite structures are required to provide space vehicles with increased thrust-to-weight ratio and durability. New methods for toughening composites...

  1. pH-dependent structural change of the extracellular sensor domain of the DraK histidine kinase from Streptomyces coelicolor

    Energy Technology Data Exchange (ETDEWEB)

    Yeo, Kwon Joo [Division of Magnetic Resonance, Korea Basic Science Institute (KBSI), 16 Yeongudanji-Ro, Ochang, Chungbuk 363-883 (Korea, Republic of); Kim, Eun Hye [Systems and Synthetic Biology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-Ro, Yuseong-Gu, Daejeon 305-333 (Korea, Republic of); Hwang, Eunha; Han, Young-Hyun; Eo, Yumi; Kim, Hyun Jung [Division of Magnetic Resonance, Korea Basic Science Institute (KBSI), 16 Yeongudanji-Ro, Ochang, Chungbuk 363-883 (Korea, Republic of); Kwon, Ohsuk [Systems and Synthetic Biology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahak-Ro, Yuseong-Gu, Daejeon 305-333 (Korea, Republic of); Hong, Young-Soo [Chemical Biology Research Center, KRIBB, 30 Yeongudanji-Ro, Ochang, Chungbuk 363-883 (Korea, Republic of); Cheong, Chaejoon, E-mail: cheong@kbsi.re.kr [Division of Magnetic Resonance, Korea Basic Science Institute (KBSI), 16 Yeongudanji-Ro, Ochang, Chungbuk 363-883 (Korea, Republic of); Cheong, Hae-Kap, E-mail: haekap@kbsi.re.kr [Division of Magnetic Resonance, Korea Basic Science Institute (KBSI), 16 Yeongudanji-Ro, Ochang, Chungbuk 363-883 (Korea, Republic of)

    2013-02-15

    Highlights: ► We described the biochemical and biophysical properties of the extracellular sensory domain (ESD) of DraK histidine kinase. ► The ESD of DraK showed a reversible pH-dependent conformational change in a wide pH range. ► The E83 is an important residue for the pH-dependent conformational change. -- Abstract: Recently, the DraR/DraK (Sco3063/Sco3062) two-component system (TCS) of Streptomycescoelicolor has been reported to be involved in the differential regulation of antibiotic biosynthesis. However, it has not been shown that under which conditions and how the DraR/DraK TCS is activated to initiate the signal transduction process. Therefore, to understand the sensing mechanism, structural study of the sensory domain of DraK is highly required. Here, we report the biochemical and biophysical properties of the extracellular sensory domain (ESD) of DraK. We observed a reversible pH-dependent conformational change of the ESD in a pH range of 2.5–10. Size-exclusion chromatography and AUC (analytical ultracentrifugation) data indicated that the ESD is predominantly monomeric in solution and exists in equilibrium between monomer and dimer states in acidic condition. Using NMR (nuclear magnetic resonance) and CD (circular dichroism) spectroscopy, our findings suggest that the structure of the ESD at low pH is more structured than that at high pH. In particular, the glutamate at position 83 is an important residue for the pH-dependent conformational change. These results suggest that this pH-dependent conformational change of ESD may be involved in signal transduction process of DraR/DraK TCS.

  2. STUDY ON THE EPOXY RESIN TOUGHENED BY HYDROXY-TERMINATED BUTADIENE-ACRYLONITRILE COPOLYMER

    Institute of Scientific and Technical Information of China (English)

    HAN Xiaozu; LI Shaoying; ZHANG Qingyu

    1990-01-01

    Toughened epoxy resin with excellent properties was obtained by adding organic acid anhydride curing agent and hydroxy-terminated butadiene-acrylonitrile copolymer (HTBN), which is cheaper than CTBN. The anhydride reacts with both epoxy groups on epoxy resin and hydroxyl groups on HTBN. As a result the soft long chains of HTBN and the rigid chain of epoxy resin form one network, giving the resin toughness. Two-phase structure of the toughened resin was observed by SEM and TEM.

  3. Influence of the morphology on mechanical properties of toughened epoxies with CTBN

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Presents a toughened-epoxy risen based on diglycidylether of bisphenol A (DGEBA) cured with ethylene-diamine (EDA) and modified with a carboxyl-terminated acrylonitrile-butadiene (CTBN), studies morphologies with different rubber content and analyses the influence of rubber-phase morphology corresponding to different rubber contents on mechanical properties (elastic modulus, uniaxial compression yield stress, shearing strength, uneven tensile strength, critical stress intensity factor Kic and strain energy release rate Gic) of toughened epoxies.

  4. Toughening of epoxy resins by epoxidized soybean oil

    Energy Technology Data Exchange (ETDEWEB)

    Frischinger, I.; Dirlikov, S. [Eastern Michigan Univ., Ypsilanti, MI (United States)

    1993-12-31

    Homogeneous mixtures of a liquid rubber based on prepolymers of epoxidized soybean oil with amines, diglycidyl ether of bisphenol A epoxy resins, and commercial diamines form, under certain conditions, two-phase thermosetting materials that consist of a rigid epoxy matrix and randomly distributed small rubbery soybean particles (0.1-5 {mu}m). These two-phase thermosets have improved toughness, similar to that of other rubber-modified epoxies, low water absorption, and low sodium content. In comparison to the unmodified thermosets, the two-phase thermosets exhibit slightly lower glass-transition temperatures and Young`s moduli, but their dielectric properties do not change. The epoxidized soybean oil is available at a price below that of commercial epoxy resins and appears very attractive for epoxy toughening on an industrial scale. 15 refs., 17 figs., 6 tabs.

  5. Suppression of X-rays during an optical outburst of the helium dwarf nova KL Dra

    CERN Document Server

    Ramsay, Gavin; Rosen, Simon; Barclay, Thomas; Steeghs, Danny

    2012-01-01

    KL Dra is a helium accreting AM CVn binary system with an orbital period close to 25 mins. Approximately every 60 days there is a 4 mag optical outburst lasting ~10 days. We present the most sensitive X-ray observations made of an AM CVn system during an outburst cycle. A series of eight observations were made using XMM-Newton which started shortly after the onset of an optical outburst. We find that X-rays are suppressed during the optical outburst. There is some evidence for a spectral evolution of the X-ray spectrum during the course of the outburst. A periodic modulation is seen in the UV data at three epochs -- this is a signature of the binary orbital or the super-hump period. The temperature of the X-ray emitting plasma is cooler compared to dwarf novae, which may suggest a wind is the origin of a significant fraction of the X-ray flux.

  6. HyDRA: gene prioritization via hybrid distance-score rank aggregation.

    Science.gov (United States)

    Kim, Minji; Farnoud, Farzad; Milenkovic, Olgica

    2015-04-01

    Gene prioritization refers to a family of computational techniques for inferring disease genes through a set of training genes and carefully chosen similarity criteria. Test genes are scored based on their average similarity to the training set, and the rankings of genes under various similarity criteria are aggregated via statistical methods. The contributions of our work are threefold: (i) first, based on the realization that there is no unique way to define an optimal aggregate for rankings, we investigate the predictive quality of a number of new aggregation methods and known fusion techniques from machine learning and social choice theory. Within this context, we quantify the influence of the number of training genes and similarity criteria on the diagnostic quality of the aggregate and perform in-depth cross-validation studies; (ii) second, we propose a new approach to genomic data aggregation, termed HyDRA (Hybrid Distance-score Rank Aggregation), which combines the advantages of score-based and combinatorial aggregation techniques. We also propose incorporating a new top-versus-bottom (TvB) weighting feature into the hybrid schemes. The TvB feature ensures that aggregates are more reliable at the top of the list, rather than at the bottom, since only top candidates are tested experimentally; (iii) third, we propose an iterative procedure for gene discovery that operates via successful augmentation of the set of training genes by genes discovered in previous rounds, checked for consistency. Fundamental results from social choice theory, political and computer sciences, and statistics have shown that there exists no consistent, fair and unique way to aggregate rankings. Instead, one has to decide on an aggregation approach using predefined set of desirable properties for the aggregate. The aggregation methods fall into two categories, score- and distance-based approaches, each of which has its own drawbacks and advantages. This work is motivated by the

  7. Distinguishing subtypes of extrinsic motivation among people with mild to borderline intellectual disability : Distinguishing subtypes of extrinsic motivation

    NARCIS (Netherlands)

    Frielink, N.; Schuengel, C.; Embregts, P.J.C.M.

    Background According to self-determination theory, motivation is ordered in types, including amotivation, extrinsic motivation and intrinsic motivation. Self-determination theory defines four subtypes of extrinsic motivation: external motivation, introjected motivation, identified motivation and

  8. Toughening of BMI Based Graphite Laminates by Ex-situ Concept

    Institute of Scientific and Technical Information of China (English)

    CHENG Qun-feng; XU Ya-hong; YI Xiao-su

    2006-01-01

    High-performance bismaleimdes (BMI) matrix composites reinforced by graphite fibers were prepared and toughened with a thermoplastic component (PAEK) by using the Ex-situ concept. Experimental matrix was designed for overall toughening of the base resin, periodically interleaving thermoplastic films into each plies (Ex-situ concept) and for varying the film compositions. The highest impact damage resistance characterized by compression after impact (CAI) was obtained for the laminates toughened on the Ex-situ concept, especially, when two-component cast films of a special ration of PAEK/BMI 60: 40 were interleaved though the thermoplastic concentration for the overall toughening, interleaving the pure thermoplastic films and the two-component films was comparable. There were two peaks found in the DSC trace of the laminates toughened implying a phase separation process occurred. The glass transition temperature of the laminates toughened was slightly reduced due to the low-temperature PAEK. Morphological study revealed a typical granular structure just in the interplay region as a result of spinodal decomposition and coarsening process. This was in agreement of the result of DSC investigation.

  9. Annealing-induced interfacial toughening using a molecular nanolayer.

    Science.gov (United States)

    Gandhi, Darshan D; Lane, Michael; Zhou, Yu; Singh, Amit P; Nayak, Saroj; Tisch, Ulrike; Eizenberg, Moshe; Ramanath, Ganapathiraman

    2007-05-17

    Self-assembled molecular nanolayers (MNLs) composed of short organic chains and terminated with desired functional groups are attractive for modifying surface properties for a variety of applications. For example, organosilane MNLs are used as lubricants, in nanolithography, for corrosion protection and in the crystallization of biominerals. Recent work has explored uses of MNLs at thin-film interfaces, both as active components in molecular devices, and as passive layers, inhibiting interfacial diffusion, promoting adhesion and toughening brittle nanoporous structures. The relatively low stability of MNLs on surfaces at temperatures above 350-400 degrees C (refs 12, 13), as a result of desorption or degradation, limits the use of surface MNLs in high-temperature applications. Here we harness MNLs at thin-film interfaces at temperatures higher than the MNL desorption temperature to fortify copper-dielectric interfaces relevant to wiring in micro- and nano-electronic devices. Annealing Cu/MNL/SiO2 structures at 400-700 degrees C results in interfaces that are five times tougher than pristine Cu/SiO2 structures, yielding values exceeding approximately 20 J m(-2). Previously, similarly high toughness values have only been obtained using micrometre-thick interfacial layers. Electron spectroscopy of fracture surfaces and density functional theory modelling of molecular stretching and fracture show that toughening arises from thermally activated interfacial siloxane bridging that enables the MNL to be strongly linked to both the adjacent layers at the interface, and suppresses MNL desorption. We anticipate that our findings will open up opportunities for molecular-level tailoring of a variety of interfacial properties, at processing temperatures higher than previously envisaged, for applications where microlayers are not a viable option-such as in nanodevices or in thermally resistant molecular-inorganic hybrid devices.

  10. Lunar-based Ultraviolet Telescope study of the well-known Algol-type binary TW Dra

    Science.gov (United States)

    Liao, Wen-Ping; Qian, Sheng-Bang; Zejda, Miloslav; Zhu, Li-Ying; Li, Lin-Jia

    2016-06-01

    By using the Lunar-based Ultraviolet Telescope (LUT) from 2014 December 2 to December 4, the first near-UV light curve of the well-known Algol-type binary TW Dra is reported, which is analyzed with the 2013 version of the W-D code. Our solutions confirmed that TW Dra is a semi-detached binary system where the secondary component fills its Roche lobe. The mass ratio and a high inclination are obtained (q = 0.47, i = 86.68°). Based on 589 available data spanning more than one century, the complex period changes are studied. Secular increase and three cyclical changes are found in the corresponding orbital period analysis. The secular increase changes reveal mass transfer from the secondary component to the primary one at a rate of 6.8 × 10-7 M ⊙ yr-1. One large cyclical change of 116.04 yr may be caused by disturbance of visual component ADS 9706B orbiting TW Dra (ADS 9706A), while the other two cyclical changes with shorter periods of 22.47 and 37.27 yr can be explained as the result of two circumbinary companions that are orbiting around TW Dra, where the two companions are in simple 3 : 5 orbit-rotation resonances. TW Dra itself is a basic binary in a possible sextuple system with the configuration (1 + 1) + (1 + 1) + (1 + 1), which further suggests that multiplicity may be a fairly common phenomenon in close binary systems.

  11. Extrinsic and intrinsic curvatures in thermodynamic geometry

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini Mansoori, Seyed Ali, E-mail: shossein@bu.edu [Department of Physics, Boston University, 590 Commonwealth Ave., Boston, MA 02215 (United States); Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Mirza, Behrouz, E-mail: b.mirza@cc.iut.ac.ir [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Sharifian, Elham, E-mail: e.sharifian@ph.iut.ac.ir [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2016-08-10

    We investigate the intrinsic and extrinsic curvatures of a certain hypersurface in thermodynamic geometry of a physical system and show that they contain useful thermodynamic information. For an anti-Reissner–Nordström-(A)de Sitter black hole (Phantom), the extrinsic curvature of a constant Q hypersurface has the same sign as the heat capacity around the phase transition points. The intrinsic curvature of the hypersurface can also be divergent at the critical points but has no information about the sign of the heat capacity. Our study explains the consistent relationship holding between the thermodynamic geometry of the KN-AdS black holes and those of the RN (J-zero hypersurface) and Kerr black holes (Q-zero hypersurface) ones [1]. This approach can easily be generalized to an arbitrary thermodynamic system.

  12. Extrinsic allergic alveolitis in Scottish maltworkers.

    Science.gov (United States)

    Grant, I W; Blackadder, E S; Greenberg, M; Blyth, W

    1976-01-01

    In a survey of respiratory disease in the Scottish malting industry 5.2% of employees were found to have symptoms of extrinsic allergic alveolitis. In most cases the disease was mild and not associated with any serious respiratory disability. It was significantly less common where modern mechanical methods of malting were used. Mycological and serological studies suggested that it was usually caused by a type 3 allergic reaction to Aspergillus clavatus. PMID:1252813

  13. Intrinsic-extrinsic factors in sport motivation.

    Science.gov (United States)

    Pedersen, Darhl M

    2002-10-01

    Participants were 83 students (36 men and 47 women). 10 intrinsic-extrinsic factors involved in sport motivation were obtained. The factors were generated from items obtained from the participants rather than items from the experimenter. This was done to avoid the possible influence of preconceptions on the part of the experimenter regarding what the final dimensions may be. Obtained motivational factors were Social Reinforcement, Fringe Benefits, Fame and Fortune, External Forces, Proving Oneself, Social Benefits, Mental Enrichment, Expression of Self, Sense of Accomplishment, and Self-enhancement. Each factor was referred to an intrinsic-extrinsic dimension to describe its relative position on that dimension. The order of the factors as listed indicates increasing intrinsic motivation. i.e., the first four factors were rated in the extrinsic range, whereas the remaining six were rated to be in the intrinsic range. Next, the participants rated the extent to which each of the various factors was involved in their decision to participate in sport activities. The pattern of use of the motivational factors was the same for both sexes except that men indicated greater use of the Fringe Benefits factor. Overall, the more intrinsic a sport motivation factor was rated, the more likely it was to be rated as a factor in actual sport participation.

  14. Ductile-Phase-Toughened Tungsten for Plasma-Facing Materials

    Science.gov (United States)

    Cunningham, Kevin Hawkins

    A variety of processing approaches were employed to fabricate ductile-phase-toughened (DPT) tungsten (W) composites. Mechanical testing and analytical modeling were used to guide composite development. This work provides a basis for further development of W composites to be used in structural divertor components of future fusion reactors. W wire was tested in tension, showing significant ductility and strength. Coatings of copper (Cu) or tungsten carbide (WC) were applied to the W wire via electrodeposition and carburization, respectively. Composites were fabricated using spark plasma sintering (SPS) to consolidate W powders together with each type of coated W wire. DPT behavior, e.g. crack arrest and crack bridging, was not observed in three-point bend testing of the sintered composites. A laminate was fabricated by hot pressing W and Cu foils together with W wires, and subsequently tested in tension. This laminate was bonded via hot pressing to thick W plate as a reinforcing layer, and the composite was tested in three-point bending. Crack arrest was observed along with some fiber pullout, but significant transverse cracking in the W plate confounded further fracture toughness analysis. The fracture toughness of thin W plate was measured in three-point bending. W plates were brazed with Cu foils to form a laminate. Crack arrest and crack bridging were observed in three-point bend tests of the laminate, and fracture resistance curves were successfully calculated for this DPT composite. An analytical model of crack bridging was developed using the basis described by Chao in previous work by the group. The model uses the specimen geometry, matrix properties, and the stress-displacement function of a ductile reinforcement ("bridging law") to calculate the fracture resistance curve (R-curve) and load-displacement curve (P-D curve) for any test specimen geometry. The code was also implemented to estimate the bridging law of an arbitrary composite using R-curve data

  15. 内蒙古地区3个马品种ELA-DRA* exon2的PCR-SSCP分析%Analyzed ELA-DRA* exon2 of Three Horse Breeds from Inner Mongolia by PCR-SSCP

    Institute of Scientific and Technical Information of China (English)

    孟青龙; 李金莲; 石有斐; 孙玉江; 芒来

    2006-01-01

    为了检测内蒙古地区3个马品种ELA-DRA*exon2的多态性,通过PCR-SSCP技术内蒙古地区3个马品种(三河马、锡尼河马和巴尔虎马)各50匹的ELA-DRA*exon2进行检测,用12%非变性聚丙烯酰胺凝胶电泳将已变性的PCR扩增产物分离,并用银染法显色.结果表明,150匹马中共出现6种基因型:3种纯合子分别记为AA,BB和CC型,均为3条带;3种杂合子分别记为AB,BC和AC型,均为4条带.其中A等位基因频率最高,B次之,而C只在三河马中出现.因此说三河马ELA-DRA *exon2的多态性比锡尼河马和巴尔虎马丰富.

  16. Synthesis and application of phenolic resin internally toughened by chain extension polymer of epoxidized soybean oil

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A novel epoxidized soybean oil (ESO) internally toughened phenolic resin(ESO-IT-PR) with both good toughness and excellent thermal stability was prepared as the matrix resin of copper clad laminate (CCL).FTIR was adopted to investigate the molecular structure of modified phenolic resins and SEM was used to observe the micro morphology of their impacted intersections.The properties of CCLs prepared with these modified phenolic resins were studied to determine the optimal process and investigate the toughening mechanism.The main modifying mechanism is the etherification reaction between phenol hydroxyl and ESO catalyzed by triethanolamine and the chain extension polymerization between ESO and multi-amine gives the long-chain ESO epoxy grafting on the phenolic resin prepolymer,when the ESO content is 30% and the curing agent content is 7%,the ESO toughened phenolic resin possesses optimal performance.The flexible ESO epoxy shows significant toughening effect and it crosslinks with the phenolic resin to form an internally toughened network,which is the key factor for improving the solderleaching resistance of CCL prepared with this modified phenolic resin.

  17. Martensitic transformation and toughening of zirconia ceramics; Jirukonia kei ceramics no marutensaito hentai to kyojinka

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, M.; Oka, M. [Tottori Univ., Tottori (Japan). Faculty of Engineering

    1994-12-20

    It has been twenty years since Garvie and et al showed that the martensitic transformation of zirconia can be used to toughen ceramics. In addition to a partially stabilized zirconia of deposited type at the initial stage of the development, materials of new forms such as single-phase type tetragonal zirconia polycrystal and zirconia toughened ceramics in which zirconia grains are dispersed in alumina have been developed during that period of time. Since the toughening properties of these materials are attributed to the martensitic transformation of zirconia, researches on the martensitic transformation behaviors of zirconia have vigorously been made. The results of the research on the transformation behaviors are useful to forecast the upper limit of the improvement of this material and the toughening which can theoretically be attained. After describing the toughening mechanism by the martensitic transformation, this report mainly introduces the results of the researches made by the writers on the crystallography of the transformation and the crystal grain size dependence by transformation behavior which are main subjects of the martensitic transformation. 23 refs., 8 figs.

  18. Effect of toughened epoxy resin on partial discharge at solid-solid interface

    Science.gov (United States)

    Manping, Li; Kai, Wu; Zhao, Zhang; Yonghong, Cheng

    2017-02-01

    A series of solid-solid interfaces, consisting of ceramic-epoxy resin interface samples with a tip-plate electrode, were investigated by performing partial discharge tests and real-time electrical tree observations. A toughening agent was added to the epoxy resin at different ratios for comparison. The impact strength, differential scanning calorimetry (DSC) and dielectric properties of the cured compositions and ceramic were tested. The electric field strength at the tip was calculated based on Maxwell’s theory. The test results show that the addition of a toughener can improve the impact strength of epoxy resin but it decreases the partial discharge inception voltage (PDIV) of the interface sample. At the same time, toughening leads to complex branches of the electrical tree. The simulation result suggests that this reduction of the PDIV cannot be explained by a change of permittivity due to the addition of a toughening agent. The microstructural change caused by toughening was considered to be the key factor for lower PDIV and complex electrical tree branches. Supported by China Academy of Engineering Physics (Project 2014B05005).

  19. Research Progress on Toughening Modification of Recycled PET%回收PET增韧改性研究进展

    Institute of Scientific and Technical Information of China (English)

    林新土; 张华集; 黄巧玲; 周为明; 陈庆华

    2013-01-01

    According to dominant drawbacks such as low crystallization rate, long processing time and poor notched impact strength of recycled poly(ethylene terephthalate)(r-PET), the research progress on the methods for toughening modification of r-PET including elastomer toughening, alloying toughening, core-shell structure polymer toughening, engineering plastics toughening and chain extender toughening was reviewed. The toughening modification research trend of r-PET is toughening r-PET with higher strength.%针对回收聚对苯二甲酸乙二酯(r-PET)存在的结晶速度慢、成型周期长、冲击性能差等缺陷,综述了采用弹性体、合金化、核壳聚合物、工程塑料、扩链剂等方法增韧改性r-PET的研究进展.r-PET增韧改性的研究方向是实现r-PET的强韧化.

  20. Research Status of Toughening Nylon Material%尼龙增韧材料的研究现状

    Institute of Scientific and Technical Information of China (English)

    霍丽; 姜巧娟

    2014-01-01

    探讨了国内外尼龙材料增韧研究的现状,目前尼龙材料增韧主要集中于以下几个方面:用尼龙与弹性体共混制备超韧尼龙,包括聚烯烃类弹性体增韧尼龙,苯乙烯类嵌段共聚物增韧尼龙,核-壳型冲击改性剂增韧尼龙,以及离聚物为增容剂增韧尼龙;无机刚性粒子增韧尼龙,能在提高材料的抗冲击性能的同时,保证不降低其拉伸强度和刚性;有机刚性粒子增韧尼龙。%The present situation of toughening research at home and abroad of nylon was discussed .The aspects of toughened nylon material were focused on that nylon and elastomeric was prepared by blending of super tough nylon , including polyolefin elastomeric toughened nylon , styrene block copolymer toughening agent toughened nylon , nylon modified core-shell impact , as well as from copolymer as compatibilizer toughened nylon , the rigid inorganic particles toughened nylon , can improve the impact properties of materials and guaranteed not to decrease of tensile strength and rigidity, and organic rigid particle toughened nylon.

  1. Graphene nanosheet-induced toughening of yttria-stabilized zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Su, Jianan; Chen, Yao; Huang, Qiqi [Soochow University, School of Mechanical and Electric Engineering, Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China)

    2017-01-15

    Graphene nanosheet (GNS)-reinforced yttria-stabilized tetragonal zirconia polycrystals (TZP) were synthesized using spark plasma sintering (SPS), and the influences of the added GNSs on microstructure evolution and the microscopic mechanical properties of the sintered composites were investigated. Raman spectroscopy and microstructure observation corroborated that these added GNSs, which can survive the harsh SPS processing condition, homogeneously distribute in the matrix of all composites to hinder significantly the grain growth. In comparison with the monolithic TZP, the indentation fracture toughness of a GNS/TZP composite reaches maximum value and increases by up to ∝36% (from ∝4.1 to ∝5.6 MPa m{sup 0.5}) even at 0.5% weight fraction, GNS pullout, crack bridging, crack deflection, and crack branching are responsible for the increased fracture toughness. The computed energy dissipation by GNS pullout decreases with increasing the number of graphene layers due to weak bonding between them, and therefore, graphene agglomeration would impair toughening effect. Moreover, scratch studies suggest that GNS/TZP composites exhibit improved scratch resistance due to the fact that GNSs are promising reinforcing and lubricating nanofillers in ceramic composites. (orig.)

  2. Toughening and creep in multiphase intermetallics through microstructural control

    Indian Academy of Sciences (India)

    A K Gogia; R G Baligidad; D Banerjee

    2003-06-01

    The lack of engineering ductility in intermetallics has limited their structural applications, in spite of their attractive specific properties at high temperatures. Over the last decade, research in intermetallics has been stimulated by the discovery of remarkable ductilisation mechanisms in these materials. It has however often been the case that the process of ductilisation or toughening has also led to a decrease in high temperature properties, especially creep. In this paper we describe approaches to the ductilisation of two different classes of intermetallic alloys through alloying to introduce beneficial, second phase effects. The Ti2AlNb based intermetallics in the Ti–Al–Nb system can be ductilised by stabilising the bcc phase of titanium into the structure. The principles of microstructural and compositional optimization developed to achieve adequate plasticity, while retaining creep properties of these alloys, are described. An entirely different approach has been successful in imparting plasticity to intermetallics based on Fe3Al. The addition of carbon to form the Fe3AlC0.5 phase imparts ductility, while enhancing both tensile and creep strength.

  3. Meat toughening does not occur when rigor shortening is prevented.

    Science.gov (United States)

    Koohmaraie, M; Doumit, M E; Wheeler, T L

    1996-12-01

    The objective of this experiment was to test the hypothesis that meat toughening during the first 24 h postmortem results from sarcomere shortening during rigor mortis development. Eleven market-weight lambs were used to measure changes in shear force of clamped longissimus during rigor development. Within 15 min of exsanguination, while attached at both ends, each longissimus was separated from the vertebrae body and clamped between three sets of metal plates to prevent muscle shortening (six clamped sections per lamb). Five of the clamped sections were placed at -1.1 degrees C for 0, 3, 6, 12, or 24 h. After storage at their respective times at -1.1 degrees C, the samples were placed at -30 degrees C for 90 min and then at -5 degrees C for 8 d. The sixth section (168-h section) was stored at -1.1 degrees C for the first 24 h, at 4 degrees C for 144 h, and then treated the same as other sampling times. Sections were sampled for pH, sarcomere length, shear force, and Western blot analyses before and after storage at -5 degrees C. Shear force values were the same (P > .05) from 0 to 24 h (4.5 kg at 0 h to 4.9 kg at 24 h) then declined (P slaughter is most likely due to sarcomere shortening.

  4. Moisture curable toughened poly(lactide utilizing vinyltrimethoxysilane based crosslinks

    Directory of Open Access Journals (Sweden)

    J. Schneider

    2016-10-01

    Full Text Available Vinyltrimethoxysilane (VTMOS was grafted on to the backbone of poly(lactide (PLA through a free radical grafting reaction using reactive extrusion (REX processing. The methoxy groups of the silane provide the modified PLA sites for crosslinking through a moisture induced pathway. VTMOS grafting efficiencies of up to 90% were obtained. The newly created methoxy functionality of the modified PLA readily undergoes hydrolysis and condensation forming siloxane crosslinks in the material. Crosslinking with VTMOS exhibited improved modulus, strength, and impact toughness while showing a decrease in ductility. Incorporating silanol-terminated poly(dimethylsiloxane (OH-PDMS resulted in the formation of longer siloxane crosslinks. These samples showed an increase in modulus and impact toughness due to the crosslinking, while the longer siloxane linkages resulted in improved ductility and tensile toughness. This is unusual for polymers toughened through crosslinking reactions. Scanning Electron Microscopy (SEM of the fractured surfaces showed the presence of these elongated siloxane crosslinks. This enhanced ability for the modified PLA to deform and absorb energy results in the increase in both impact and tensile toughness.

  5. Crack Propagation in a Toughened Epoxy Adhesive under Repeated Impacts

    Directory of Open Access Journals (Sweden)

    Ian A. Ashcroft

    2011-01-01

    Full Text Available Adhesives are being increasingly used in structural applications, especially in aerospace, automotive and naval structures, making their structural integrity an important issue. In-service loading histories of such structures usually contain low-energy impacts, repetition of which can significantly affect their performance. This paper deals with the behaviour of the toughened epoxy adhesive FM73 under repeated impacts, known as impact fatigue. Izod impact fatigue tests were performed on FM73 specimens in order to study the evolution of damage and to characterise this via measurable parameters, such as the maximum force and the contact time. A finite element model was developed to simulate the impact tests and this was used to calculate the dynamic strain energy release rate, which was compared with that determined using a simple analytical method. A relationship between the maximum dynamic strain energy release rate and impact fatigue crack growth rate was established that was used as the basis of an impact fatigue crack growth law.

  6. Velocity Curve Analysis of Spectroscopic Binary Stars AI Phe, GM Dra, HD 93917 and V502 Oph by Nonlinear Regression

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We introduce a new method to derive the orbital parameters of spectroscopic binary stars by nonlinear least squares of (o - c). Using the measured radial velocity data of the four double lined spectroscopic binary systems,AI Phe,GM Dra,HD 93917 and V502 Oph,we derived both the orbital and combined spectroscopic elements of these systems.Our numerical results are in good agreement with the those obtained using the method of Lehmann-Filhés.

  7. Preparation of Nano-Scale Biopolymer Extracted from Coconut Residue and Its Performance as Drag Reducing Agent (DRA

    Directory of Open Access Journals (Sweden)

    Hasan Muhammad Luqman Bin

    2017-01-01

    Full Text Available Drag or frictional force is defined as force that acts opposite to the object’s relative motion through a fluid which then will cause frictional pressure loss in the pipeline. Drag Reducing Agent (DRA is used to solve this issue and most of the DRAs are synthetic polymers but has some environmental issues. Therefore for this study, biopolymer known as Coconut Residue (CR is selected as the candidate to replace synthetic polymers DRA. The objective of this study is to evaluate the effectiveness of Nano-scale biopolymer DRA on the application of water injection system. Carboxymethyl cellulose (CMC is extracted by synthesizing the cellulose extracted from CR under the alkali-catalyzed reaction using monochloroacetic acid. The synthesize process is held in controlled condition whereby the concentration of NaOH is kept at 60%wt, 60 °C temperature and the reaction time is 4 hours. For every 25 g of dried CR used, the mass of synthesized CMC yield is at an average of 23.8 g. The synthesized CMC is then grinded in controlled parameters using the ball milling machine to get the Nano-scale size. The particle size obtained from this is 43.32 Nm which is in range of Nano size. This study proved that Nano-size CMC has higher percentage of drag reduction (%DR and flow increase (%FI if compared to normal-size CMC when tested in high and low flow rate; 44% to 48% increase in %DR and %FI when tested in low flow rate, and 16% to 18% increase in %DR and %FI when tested in high flow rate. The success of this research shows that Nano-scale DRA can be considered to be used to have better performance in reducing drag.

  8. Brief Note Low diversity of the major histocompatibility complex class II DRA gene in domestic goats (Capra hircus) in Southern China.

    Science.gov (United States)

    Chen, L P; E, G X; Zhao, Y J; Na, R S; Zhao, Z Q; Zhang, J H; Ma, Y H; Sun, Y W; Zhong, T; Zhang, H P; Huang, Y F

    2015-06-18

    DRA encodes the alpha chain of the DR heterodimer, is closely linked to DRB and is considered almost monomorphic in major histocompatibility complex region. In this study, we identified the exon 2 of DRA to evaluate the immunogenetic diversity of Chinese south indigenous goat. Two single nucleotide polymorphisms in an untranslated region and one synonymous substitution in coding region were identified. These data suggest that high immunodiversity in native Chinese population.

  9. Photometric analysis of overcontact binaries AK Her, HI Dra, V1128 Tau and V2612 Oph

    CERN Document Server

    Caliskan, S; Djurasevic, G; Ozavci, I; Basturk, O; Cseki, A; Senavci, H V; Kilicoglu, T; Yilmaz, M; Selam, S O

    2014-01-01

    We analyze new, high quality multicolor light curves of four overcontact binaries: AK Her, HI Dra, V1128 Tau and V2612 Oph, and determine their orbital and physical parameters using the modeling program of G. Djurasevic and recently published results of radial velocity studies. The achieved precision in absolute masses is between 10 and 20%, and in absolute radii between 5 and 10%. All four systems are W UMa type binaries with bright or dark spots indicative of mass and energy transfer or surface activity. We estimate the distances and the ages of the systems using the luminosities computed through our analysis, and perform an O-C study for V1128 Tau, which reveals a complex period variation that can be interpreted in terms of mass loss/exchange and either the presence of the third body, or the magnetic activity on one of the components. We conclude that further observations of these systems are needed to deepen our understanding of their nature and variability.

  10. Association between Genetic Polymorphism in the Swine Leukocyte Antigen-DRA Gene and Piglet Diarrhea in Three Chinese Pig Breeds.

    Science.gov (United States)

    Yang, Q L; Zhao, S G; Wang, D W; Feng, Y; Jiang, T T; Huang, X Y; Gun, S B

    2014-09-01

    The swine leukocyte antigen (SLA)-DRA locus is noteworthy among other SLA class II loci for its limited variation and has not been investigated in depth. This study was investigated to detect polymorphisms of four exons of SLA-DRA gene and its association with piglet diarrhea in Landrace, Large White and Duroc pigs. No polymorphisms were detected in exon 3, while 2 SNPs (c.178G>A and c.211T>C), 2 SNPs (c.3093A>C and c.3104C>T) and 5 SNPs (c.4167A>G, c.4184A>G, c.4194A>G, c.4246A>G and c.4293G>A) were detected in exon 1, exon 2 and exon 4 respectively, and 1 SNP (c.4081T>C) in intron 3. Statistical results showed that genotype had significant effect on piglet diarrhea, individuals with genotype BC had a higher diarrhea score when compared with the genotypes AA, AB, AC and CC. Futhermore, genotype AC had a higher diarrhea score than the genotype CC in exon 1 (ppiglet diarrhea appeared that Hap2, 5, 8, 10, and 14 may be the susceptible haplotypes and Hap9 may be the resistant haplotype to piglet diarrhea. The genetic variations identified of the SLA-DRA gene may potentially be functional mutations related to piglet diarrhea.

  11. Toughening mechanism of lined Al2O3-ZrO2 multiphase ceramics in SHS composite pipes

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Hypoeutectic and hypereutectic Al2O3-ZrO2 multiphase ceramics-lined composite pipes were produced by using the gravitational separation self-propagate high-temperature synthesis (SHS) process.The microstructure of the ceramics was observed by means of SEM and EPMA.The fracture toughness of the multiphase ceramics was tested by using the Vickers indentation method.The ceramics is 15.23 Mpa.m1/2.The toughening mechanisms were systematically investigated by means of SEM and XRD.The results show that the bridging toughening mechanism, stress induced ZrO2 transformation toughening mechanism, and microcrack toughening mechanism are the predominant toughening mechanism.

  12. Numerical Simulations of Dynamic Behavior of Polyurea Toughened Steel Plates under Impact Loading

    Directory of Open Access Journals (Sweden)

    Chien-Chung Chen

    2014-01-01

    Full Text Available The objective of the work discussed herein is to develop a nonlinear 3D finite element model to simulate dynamic behavior of polyurea toughened steel plates under impact loading. Experimental and numerical work related to model development are presented. Material properties are incorporated into numerical models to account for strain-rate effects on the dynamic behavior of polyurea and steel. One bare steel plate and four polyurea toughened steel plates were tested under impact loading using a pendulum impact device. Displacement time-history data from experimental work was used to validate the numerical models. Details on material model construction, finite element model development, and model validation are presented and discussed. Results indicate that the developed numerical models can reasonably predict dynamic response of polyurea toughened steel plates under impact loading.

  13. 回收ABS增韧研究%Study on Toughening of Recycled ABS

    Institute of Scientific and Technical Information of China (English)

    戴伟民

    2011-01-01

    Acrylonitrile-butadiene-styrene (ABS) high-rubber powder (HRP),SBS and TPU were used to toughen recycled ABS. The results show that the toughening effect of ABS HRP is better than that of TPU and SBS.TPU toughening recycled ABS can keep the other aspects of the mechanical properties of ABS and improve flow properties of ABS.%研究了丙烯腈-丁二烯-苯乙烯共聚物(ABS)高胶粉(HRP)、苯乙烯-丁二烯-苯乙烯共聚物(SBS)、热塑性聚氨酯(TPU)对回收ABS的增韧效果.研究表明,ABS高胶粉的增韧效果最佳,而TPU在增韧回收ABS的同时可保持ABS的其他方面的力学性能并提高其流动性.

  14. [Recent advances in extrinsic allergic alveolitis].

    Science.gov (United States)

    Sennekamp, J; Joest, M

    2008-01-01

    Extrinsic allergic alveolitis (hypersensitivity pneumonitis), especially humidifier lung, has been more frequently diagnosed over the last decades, whereas farmer's lung has decreased over the same time period. Today two types of the chronic course of extrinsic allergic alveolitis can be distinguished. The recurrent chronic course with a good prognosis may be differentiated from the insidious course with a poor prognosis by means of different histological patterns (UIP, NSIP, BOOP pattern). The characteristic neutrophilic infiltration of the lung in the insidious course cannot be detected by bronchoalveolar lavage (BAL) methods. Furthermore, lymphocytosis in the BAL can be absent or present at a low level. The CD4/CD8 ratio is not always decreased and may be normal or even increased in these insidious cases with a poor prognosis. Granulomas in the lung tissue, however, point to a good prognosis. In the diagnostic work-up of machine operator's and humidifier lung, it is advisable not only to look for serum antibodies against bacteria and molds but also for rapid growing mycobacteria in a sample of machine or humidifier water. IgM and IgG rheumatoid factors occur frequently in allergic alveolitis, especially in humidifier lung. The patients, however, do not suffer from arthritis. The IgM rheumatoid factor may simulate IgM antibodies against numerous infectious agents (e. g., Bordetella pertussis or Mycoplasma pneumoniae). Taking this phenomenon into account may improve the current differential diagnosis of allergic alveolitis.

  15. Evolving extrinsic curvature and the cosmological constant problem

    Science.gov (United States)

    Capistrano, Abraão J. S.; Cabral, Luis A.

    2016-10-01

    The concept of smooth deformation of Riemannian manifolds associated with the extrinsic curvature is explained and applied to the Friedmann-Lemaître-Robertson-Walker cosmology. We show that such deformation can be derived from the Einstein-Hilbert-like dynamical principle may produce an observable effect in the sense of Noether. As a result, we show how the extrinsic curvature compensates both quantitative and qualitative differences between the cosmological constant Λ and the vacuum energy {ρ }{vac} obtaining the observed upper bound for the cosmological constant problem at electroweak scale. The topological characteristics of the extrinsic curvature are discussed showing that the produced extrinsic scalar curvature is an evolving dynamical quantity.

  16. On the Use of Self-Assembling Block Copolymers to Toughen A Model Epoxy

    Science.gov (United States)

    Chen, Yilin

    Block copolymers have been receiving considerable attention in toughening epoxy due to their ability to form a wide variety of nanostructures. This study focuses on using both triblock and diblock copolymers to improve the fracture toughness of an aromatic-amine cured epoxy system. The curing system consisted of 1,3- phenylenediamine (mPDA) as curing agent and aniline as a chain extender. Three triblock copolymers and three diblock copolymers were incorporated in the same lightly crosslinked model epoxy system, which was chosen to mimic an underfill material in flip-chip packaging for the microelectronics industry. In this research, rubber particles were formed in situ using self-assembling block copolymers. Mechanical, thermal and microscopic studies were conducted with the main goal to study the relationship between the block parameters and the final morphologies and their effects on static and dynamic mechanical properties of the toughened resin, especially fracture toughness. In these block-copolymer-modified epoxies, spherical micelles and wormlike micelles were obtained by varying block lengths, molecular weight, polarities and compositions. It was found that miscibility of the epoxy-miscible block played a crucial role in the formation of different types of morphologies. At a low loading level, diblock copolymers were able to toughen the model epoxy as effectively as triblock copolymers. The fracture toughness was improved to almost three times with respect to that of the neat resin with addition of 10 phr AM*-27. At the same time, other mechanical properties, such as yield strength and modulus, were well retained. Incorporation of block copolymers did not have a significant effect on glass transition temperature but caused an increase in coefficient of thermal expansion (CTE) of the modified epoxy. Particle cavitation and matrix void growth were proved to be the toughening mechanisms for SBM-Modified epoxies. However, these typical toughening mechanisms for

  17. Analysis of whisker-toughened ceramic components - A design engineer's viewpoint

    Science.gov (United States)

    Duffy, Stephen F.; Manderscheid, Jane M.; Palko, Joseph L.

    1989-01-01

    The analysis of components fabricated from whisker-toughened ceramic matrix composites requires a departure from the 'factor-of-safety' design philosophy prevalent in the design of metallic structural component, which are more tolerant of flaws. A public-domain computer algorithm has been developed which, in conjunction with a general-purposed FEM program, can predict the fast-fracture reliability of a structural component under multiaxial loading conditions. The present version of the algorithm, designated 'Toughened Ceramics Analysis and Reliability Evaluation of Structures', accounts for material symmetry imposed by whisker orientation; the processes of crack deflection and crack pinning are also addressed.

  18. An implementation of 3D viscoelatic behavior for glass during toughening

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes; Stang, Henrik;

    2007-01-01

    The paper presents a derivation of an incremental formulation for the thermorheological material behavior of glass during the toughening process. The objective of this paper is to provide a constitutive relationship and a discussion for implementing a 3D thermo-viscoelastic material in a numerical...... simulation based on the Finite Element Method. Furthermore, an analytical solution for testing the implementation and a 3D example of toughening – the strip model are described. The basic equations provided are general and have been implemented and tested in a user supplied subroutine in the commercial FE...

  19. Toughening of wood plastic composite based on X-PP

    Science.gov (United States)

    Meekum, U.; Khongrit, A.

    2016-03-01

    Wood plastic composite(WPC) based on crosslinked polypropylene(X-PP)/wood flour was explored. The peroxide/silane was used as crosslinking system. The sauna incubation under moisture saturated oven was applied to accelerate the competition of the siloxy/moisture networking reaction. There were three parts of the research work; design of experiment, toughening of WPC and the effect of peroxide, silane and PP copolymer on properties of the WPC, respectively. In this published work, the toughness improvement of the composite was focused. Ultra-high molecular weight polyethylene (UHMWPE) and Ethylene propylene diene terpolymer(EPDM) were employed to improve impact strength via blending with x-PP matrix. Composites were compounded into pellets by co-rotational twin screw extruder and test specimens were prepared by injection molding. Sauna incubation at 105°C for 12 hrs in oven chamber was performed to accelerate the final silane condensation crosslink reaction. MFI, impact strength, flexural properties and heat deflection temperature measurement were conducted. Impact strength, HDT and flexural modulus were improved with increasing UHMWPE content, and the optimal values around 5-10 phr of UHMWPE were achieved. Addition of EPDM elastomer to the matrix blends, reduced flexural strength and modulus but increased impact strength. While incorporation of EPDM into the PP/UHMWPE blends was exhibited much higher impact strength than that of the PP/UHMWPE binary blends. Silane crosslinked through sauna treatment improved the impact strength. HDT were also much risen for the crosslinked composite comparing with the non-crosslinked one.

  20. Biologically inspired autonomous structural materials with controlled toughening and healing

    Science.gov (United States)

    Garcia, Michael E.; Sodano, Henry A.

    2010-04-01

    the system to its original operating state. The entire system will effectively detect, self toughen, and subsequently heal damage as biological materials such as bone does.

  1. Long-Term Starspot Activity of Some Chromospherically Active Rs CVn and BY Dra Stars

    Science.gov (United States)

    Kozhevnikova, Alla; Ilya, Alekseev

    2016-10-01

    We present results of our long-term photometric observations of a sample of 15 chromospherically active BY Dra and RS CVn-type stars. Observations were carried out at a 70-cm telescope and multichannel photometer of Kourovka Astronomical Observatory of Ural Federal University and at a 1.25-m telescope of Crimean Astrophysical Observatory from 2003 to 2015 in Johnson B, V, R, I bands. We also use the previously published photometric data for all these stars to find the meaning of historical star's brightness, that we assume as a brightness of unspotted photosphere. Using a renewed zonal spot model for spotted stellar photospheres we determined spot parameters for all observational seasons, as our as published ones, that were spanning almost over 45 years for some stars (e.g. CG Cyg, WY Cnc, EV Lac, V 1396 Cyg). It is shown that the spots were located at low and middle latitudes up to 58 deg., are cooler than the surrounding photosphere by 200 - 2000 K according to the spectral class. The spotted area varied from season to season, comprising 13%-47% of the surface area of the star. Almost half of the stars display drifts of their spots towards the equator and poles during certain time intervals; however, the speeds of the spots' latitude drifts are lower than the analogous speeds for sunspots, by factors of 1.5-4, on average. Activity cycles lasting from 5 to 40 years have been determined or confirmed for majority of the studied stars. As a rule, cycles are expressed in synchronous variations of spot areas, spot latitudes and average photometric star's brightness.

  2. Extrinsic allergic alveolitis caused by misting fountains.

    Science.gov (United States)

    Koschel, Dirk; Stark, Wolfram; Karmann, Fritz; Sennekamp, Jochen; Müller-Wening, Dietrich

    2005-08-01

    Recently, an increasing number of patients were presented to our clinics with febrile and respiratory symptoms associated with exposure to a new type of domestic ultrasonic humidifier. We report on 11 patients who developed recurrent episodes of fever, cough and dyspnea after repeated exposure to ultrasonic misting fountains at home. A diagnosis of extrinsic allergic alveolitis (EAA) or toxic alveolitis was made on the basis of the history and the clinical, radiological, laboratory and immunological findings. Eight patients were subjected to inhalative challenge tests with their own ultrasonic misting fountains, and all of them exhibited positive reactions. Nine patients were diagnosed with an EAA (humidifier lung) and two patients with a toxic alveolitis (humidifier fever). This study demonstrates the potential for ultrasonic misting fountains to cause illness in the home. In view of the increasing popularity of these devices, humidifier lung and humidifier fever should be considered in the differential diagnosis of patients with unexplained pulmonary or flu-like illnesses with fever.

  3. [Extrinsic allergic alveolitis--rarely diagnosed disease].

    Science.gov (United States)

    Lauková, D; Marget, I; Plutinský, J

    2009-05-01

    Extrinsic allergic alveolitis (EAA), known as hypersensitive pneumonitis, causes interstitial lung involvement by inhaled antigen. The clinical presentation of the disease has been defined as acute, subacute and chronic. The most often symptoms of the acute form of the disease are flu-like symptoms, dyspnoe and cough. The progressive dyspnoe in particullary is characterized for the chronic form of EAA. Dyspnoe is worsed, if the disease is combinied with usual respiratory infection or reexposition of inhaled antigen. It seems the diagnostic definition of EAA should be easy and prevalence of EAA relative high. The disease belongs to the group of interstitial lung diseases and it is underestimated as a matter of fact. The clinic, radiographic, laboratory and histologic abnormalities are results of inhaled antigen contact and support the diagnosis of EAA. Specific IgG antibodies against the offending antigen along with them are consedered to be detected (established) of EAA.

  4. Extrinsic and intrinsic determinants of nerve regeneration

    Directory of Open Access Journals (Sweden)

    Toby A. Ferguson

    2011-01-01

    Full Text Available After central nervous system (CNS injury axons fail to regenerate often leading to persistent neurologic deficit although injured peripheral nervous system (PNS axons mount a robust regenerative response that may lead to functional recovery. Some of the failures of CNS regeneration arise from the many glial-based inhibitory molecules found in the injured CNS, whereas the intrinsic regenerative potential of some CNS neurons is actively curtailed during CNS maturation and limited after injury. In this review, the molecular basis for extrinsic and intrinsic modulation of axon regeneration within the nervous system is evaluated. A more complete understanding of the factors limiting axonal regeneration will provide a rational basis, which is used to develop improved treatments for nervous system injury.

  5. Intrinsic and Extrinsic Motivation for Stereotypic and Repetitive Behavior

    Science.gov (United States)

    Joosten, Annette V.; Bundy, Anita C.; Einfeld, Stewart L.

    2009-01-01

    This study provides evidence for intrinsic and extrinsic motivators for stereotypical and repetitive behavior in children with autism and intellectual disability and children with intellectual disability alone. We modified the Motivation Assessment Scale (MAS) (1988b); dividing it into intrinsic and extrinsic measures and adding items to assess…

  6. A prototype empirical framework of intrinsic and extrinsic EERQI indicators

    NARCIS (Netherlands)

    Mooij, Ton

    2012-01-01

    The research question is: What do statistical analyses show us about the relationships between intrinsic and extrinsic indicators of quality and what does this mean when constructing a prototype EERQI framework? The pilot study involved the scoring on both intrinsic and extrinsic indica-tors for 177

  7. Extrinsic Isoperimetric Analysis on Submanifolds with Curvatures bounded from below

    DEFF Research Database (Denmark)

    Markvorsen, Steen; Palmer, Vicente

    2010-01-01

    within the extrinsic ball from a given starting point before they hit the boundary of the extrinsic ball. In those cases, where we may extend our analysis to hold all the way to infinity, we apply a capacity comparison technique to obtain a sufficient condition for the submanifolds to be parabolic, i...

  8. Recruiter-Applicant Differences in Perceptions of Extrinsic Rewards.

    Science.gov (United States)

    David, Kermit R., Jr.; And Others

    1991-01-01

    Examined how accurate recruiters would be in estimating relative preferences of college seniors for important category of extrinsic rewards. Compared preferences of 602 graduating college seniors for 11 extrinsic rewards with preference estimates of 486 recruiters. Recruiters underestimated importance of medical and life insurance, pension plans,…

  9. Extrinsic Rewards Are Education's Past, Not Its Future.

    Science.gov (United States)

    Schaps, Eric; Lewis, Catherine

    1991-01-01

    Robert Slavin's position--that extrinsic rewards promote student motivation and learning--may be valid within the context of a "facts-and-skills" curriculum. However, extrinsic rewards are unnecessary when schools offer engaging learning activities; programs addressing social, ethical, and cognitive development; and a supportive…

  10. Knowledge and tools formalization in the accidental risks domain (DRA-35) {omega}-13 Boilover; Formalisation du savoir et des outils dans le domaine des risques accidentels (DRA-35) {omega}-13 BOILOVER

    Energy Technology Data Exchange (ETDEWEB)

    Patej, S

    2003-03-15

    Since 2000 the Ministry of the environment is financing a studies and researches program, called since 2003 ''formalization of the knowledge and tools in the domain of the major risks'' DRA-35. The aim of this program is to realize a document formalizing the INERIS expertise in the domain of the accidental risks: the physical phenomenon implied in the accidents, the risks analysis and control, the methodological aspects for the realization of regulations. This report presents the study of the boilover physical phenomenon. (A.L.B.)

  11. Processing and properties of pressable ceramic with non-uniform reinforcement for selective-toughening

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Wei [School of Mechanical and Chemical Engineering, The University of Western Australia, Perth, WA 6009 (Australia); School of Dentistry, The University of Western Australia, WA 6009 (Australia); Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004 (China); Hu, Xiaozhi, E-mail: xiao.zhi.hu@uwa.edu.au [School of Mechanical and Chemical Engineering, The University of Western Australia, Perth, WA 6009 (Australia); Ichim, Paul [School of Dentistry, The University of Western Australia, WA 6009 (Australia); Sun, Xudong [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004 (China)

    2012-12-15

    Brittle low-strength and low-toughness pressable dental ceramic can be reinforced by ductile elongated gold-particles (GP). A customized crown structure can be adequately strengthened by distributing GP only in critical sections of the crown, where high tensile stresses are experienced. In the present study, a non-uniformly structured ceramic-matrix composite with excellent interfacial bonding, twofold fracture toughness and strength at desired locations, is fabricated using pressable dental ceramic and GP. The layout pattern and sequence of different GP/ceramic powder mixtures, high-temperature flow properties of these mixtures during hot-pressing and the sample mold geometry are used to control the distribution and locations of GP for selective toughening and strengthening. Nano-crystalline structures of the pressable ceramic-matrix and the nano-scaled interfacial region around GP have been revealed by high-magnification field-emission scanning electron microscopy. Toughening and strengthening mechanisms of the elongated GP including residual stresses from composite processing and ductile fracture of GP are discussed together with SEM observations. Bulk flexural strength and local micro-indentation fracture and deformation characteristics of the selective-toughened ceramic/metal composite have been compared to those of the monolithic pressable ceramic to validate the toughening and strengthening mechanisms.

  12. Properties of two composite materials made of toughened epoxy resin and high-strain graphite fiber

    Science.gov (United States)

    Dow, Marvin B.; Smith, Donald L.

    1988-01-01

    Results are presented from an experimental evaluation of IM7/8551-7 and IM6/18081, two new toughened epoxy resin, high strain graphite fiber composite materials. Data include ply-level strengths and moduli, notched tension and compression strengths and compression-after-impact assessments. The measured properties are compared with those of other graphite-epoxy materials.

  13. Properties of toughened RTM composites by structural toughening layer%结构化增韧层增韧RTM复合材料性能

    Institute of Scientific and Technical Information of China (English)

    张朋; 刘刚; 胡晓兰; 包建文; 益小苏

    2012-01-01

    Based on ex-situ toughening concept,the polyamide nonwoven fabric(PNF) with high porosity was chosen as structural toughening layer,and the U3160 carbon fiber reinforced epoxy 3266 composites toughened by interlaminar PNF(U3160-PNF/3266) was fabricated via RTM process.The properties of U3160-PNF/3266 composite were investigated as well as toughening mechanism.The results indicate that the PNF still keep original structure in composites interlaminar,and formed a unreactional co-continuous structure with based resin which show remarkable toughening effect.Mode Ⅰ fracture toughness(GⅠ C) and mode Ⅱ fracture toughness(GⅡ C) of the U3160-PNF/3266 composites are 1.1 times and 1.4 times higher respectively than that of the control system,and the compression after impact(CAI) increase from 212 MPa to 281 MPa.%从复合材料离位增韧思想出发,选用具有高孔隙率的尼龙无纺布(PNF)作为结构化增韧层,采用RTM工艺制备了PNF层间增韧改性的U3160碳纤维增强环氧3266树脂基复合材料(U3160-PNF/3266),并研究了其韧性相关性能和增韧机制。结果表明:U3160-PNF/3266复合材料层间仍保持其原有的结构形式,同时与层间树脂相互贯穿形成了一种非反应诱导相分离的双连续结构,并且这种双连续结构表现出显著的增韧效果。U3160-PNF/3266复合材料的Ⅰ型层间断裂韧性和Ⅱ型层间断裂韧性分别提高了1.1倍和1.4倍,冲击后压缩强度由212MPa提高到281MPa。

  14. A structural study of the interaction between the Dr haemagglutinin DraE and derivatives of chloramphenicol

    Energy Technology Data Exchange (ETDEWEB)

    Pettigrew, David M.; Roversi, Pietro [Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE (United Kingdom); Davies, Stephen G.; Russell, Angela J. [Department of Chemistry, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA (United Kingdom); Lea, Susan M., E-mail: susan.lea@path.ox.ac.uk [Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE (United Kingdom)

    2009-06-01

    The structures of two Dr adhesin (DraE) complexes with chloramphenicol derivatives, namely chloramphenicol succinate and bromamphenicol, have been solved. The structures reveal important functional groups for small-molecule binding and imply possible modifications to the molecule that would permit a more wide-ranging interaction without the toxic side effects associated with chloramphenicol. Dr adhesins are expressed on the surface of uropathogenic and diffusely adherent strains of Escherichia coli. The major adhesin subunit (DraE/AfaE) of these organelles mediates attachment of the bacterium to the surface of the host cell and possibly intracellular invasion through its recognition of the complement regulator decay-accelerating factor (DAF) and/or members of the carcinoembryonic antigen (CEA) family. The adhesin subunit of the Dr haemagglutinin, a Dr-family member, additionally binds type IV collagen and is inhibited in all its receptor interactions by the antibiotic chloramphenicol (CLM). In this study, previous structural work is built upon by reporting the X-ray structures of DraE bound to two chloramphenicol derivatives: chloramphenicol succinate (CLS) and bromamphenicol (BRM). The CLS structure demonstrates that acylation of the 3-hydroxyl group of CLM with succinyl does not significantly perturb the mode of binding, while the BRM structure implies that the binding pocket is able to accommodate bulkier substituents on the N-acyl group. It is concluded that modifications of the 3@@hydroxyl group would generate a potent Dr haemagglutinin inhibitor that would not cause the toxic side effects that are associated with the normal bacteriostatic activity of CLM.

  15. The use of a medical dictionary for regulatory activities terminology (MedDRA) in prescription-event monitoring in Japan (J-PEM).

    Science.gov (United States)

    Yokotsuka, M; Aoyama, M; Kubota, K

    2000-07-01

    The Medical Dictionary for Regulatory Activities Terminology (MedDRA) version 2.1 (V2.1) was released in March 1999 accompanied by the MedDRA/J V2.1J specifically for Japanese users. In prescription-event monitoring in Japan (J-PEM), we have employed the MedDRA/J for data entry, signal generation and event listing. In J-PEM, the lowest level terms (LLTs) in the MedDRA/J are used in data entry because the richness of LLTs is judged to be advantageous. A signal is generated normally at the preferred term (PT) level, but it has been found that various reporters describe the same event using descriptions that are potentially encoded by LLTs under different PTs. In addition, some PTs are considered too specific to generate the proper signal. In the system used in J-PEM, when an LLT is selected as a candidate to encode an event, another LLT under a different PT, if any, is displayed on the computer screen so that it may be coded instead of, or in addition to, the candidate LLT. The five-level structure of the MedDRA is used when listing events but some modification is required to generate a functional event list.

  16. Validation of a new test for Schistosoma haematobium based on detection of Dra1 DNA fragments in urine: evaluation through latent class analysis.

    Directory of Open Access Journals (Sweden)

    Olufunmilola Ibironke

    2012-01-01

    Full Text Available BACKGROUND: Diagnosis of urogenital schistosomiasis in chronically infected adults is challenging but important, especially because long term infection of the bladder and urinary tract can have dire consequences. We evaluated three tests for viable infection: detection of parasite specific DNA Dra1 fragments, haematuria and presence of parasite eggs for sensitivity (Se and specificity (Sp. METHODS: Over 400 urine specimens collected from adult volunteers in an endemic area in Western Nigeria were assessed for haematuria then filtered in the field, the filter papers dried and later examined for eggs and DNA. The results were stratified according to sex and age and subjected to Latent Class analysis. CONCLUSIONS: Presence of Dra1 in males (Se=100%; Sp=100% exceeded haematuria (Se=87.6%: Sp=34.7% and detection of eggs (Se=70.1%; Sp=100%. In females presence of Dra1 was Se=100%: Sp=100%, exceeding haematuria (Se=86.7%: Sp=77.0% and eggs (Se=70.1%; Sp=100%. Dra1 became undetectable 2 weeks after praziquantel treatment. We conclude detection of Dra1 fragment is a definitive test for the presence of Schistosoma haematobium infection.

  17. ADP-ribosylation of dinitrogenase reductase in Azospirillum brasilense is regulated by AmtB-dependent membrane sequestration of DraG.

    Science.gov (United States)

    Huergo, Luciano F; Souza, Emanuel M; Araujo, Mariana S; Pedrosa, Fábio O; Chubatsu, Leda S; Steffens, Maria B R; Merrick, Mike

    2006-01-01

    Nitrogen fixation in some diazotrophic bacteria is regulated by mono-ADP-ribosylation of dinitrogenase reductase (NifH) that occurs in response to addition of ammonium to the extracellular medium. This process is mediated by dinitrogenase reductase ADP-ribosyltransferase (DraT) and reversed by dinitrogenase reductase glycohydrolase (DraG), but the means by which the activities of these enzymes are regulated are unknown. We have investigated the role of the P(II) proteins (GlnB and GlnZ), the ammonia channel protein AmtB and the cellular localization of DraG in the regulation of the NifH-modification process in Azospirillum brasilense. GlnB, GlnZ and DraG were all membrane-associated after an ammonium shock, and both this membrane sequestration and ADP-ribosylation of NifH were defective in an amtB mutant. We now propose a model in which membrane association of DraG after an ammonium shock creates a physical separation from its cytoplasmic substrate NifH thereby inhibiting ADP-ribosyl-removal. Our observations identify a novel role for an ammonia channel (Amt) protein in the regulation of bacterial nitrogen metabolism by mediating membrane sequestration of a protein other than a P(II) family member. They also suggest a model for control of ADP-ribosylation that is likely to be applicable to all diazotrophs that exhibit such post-translational regulation of nitrogenase.

  18. Introducing SummerTime: a package for high-precision computation of sums appearing in DRA method

    CERN Document Server

    Lee, Roman N

    2015-01-01

    We introduce the Mathematica package SummerTime for arbitrary-precision computation of sums appearing in the results of DRA method. So far these results include the following families of the integrals: 3-loop onshell massless vertices, 3-loop onshell mass operator type integrals, 4-loop QED-type tadpoles, 4-loop massless propagators. The package can be used for high-precision numerical computation of the expansion coefficients of the integrals from the above families around arbitrary space-time dimension. In addition, this package can also be used for calculation of multiple zeta values, harmonic polylogarithms and other transcendental numbers expressed in terms of nested sums with factorized summand.

  19. Free Radicals and Extrinsic Skin Aging

    Directory of Open Access Journals (Sweden)

    Borut Poljšak

    2012-01-01

    Full Text Available Human skin is constantly directly exposed to the air, solar radiation, environmental pollutants, or other mechanical and chemical insults, which are capable of inducing the generation of free radicals as well as reactive oxygen species (ROS of our own metabolism. Extrinsic skin damage develops due to several factors: ionizing radiation, severe physical and psychological stress, alcohol intake, poor nutrition, overeating, environmental pollution, and exposure to UV radiation (UVR. It is estimated that among all these environmental factors, UVR contributes up to 80%. UV-induced generation of ROS in the skin develops oxidative stress, when their formation exceeds the antioxidant defence ability of the target cell. The primary mechanism by which UVR initiates molecular responses in human skin is via photochemical generation of ROS mainly formation of superoxide anion (O2−•, hydrogen peroxide (H2O2, hydroxyl radical (OH•, and singlet oxygen (1O2. The only protection of our skin is in its endogenous protection (melanin and enzymatic antioxidants and antioxidants we consume from the food (vitamin A, C, E, etc.. The most important strategy to reduce the risk of sun UVR damage is to avoid the sun exposure and the use of sunscreens. The next step is the use of exogenous antioxidants orally or by topical application and interventions in preventing oxidative stress and in enhanced DNA repair.

  20. Plasma opening switch with extrinsic magnetic field

    CERN Document Server

    Dolgachev, G; Maslennikov, D

    2001-01-01

    Summary form only given, as follows. We have demonstrated in series of experiments that plasma opening switch (POS) switching voltage (UPOS) is defined by energy density (w) deposited in the POS plasma. If we then consider a plasma erosion mainly responsible for the effect of POS switching (the erosion effect could be described by Hall or Child-Langmuir models) the energy density (w) could be measured as a function of a system "macro-parameter" such as the initial charging voltage of the capacity storage system (the Marx pulsed voltage generator) UMarx. The POS voltage in this case could be given by UPOS"aw=aUMarx4/7, where a is a constant. This report demonstrates that for the high-impedance POS which has limited charge density transferred through the POS plasma a"2.5 (MV3/7) with no external magnetic field applied. The use of the extrinsic magnetic field allows to increase a up to 3.6 (MV3/7) and to achieve higher voltages at the opening phase - UPOS=3.6UMarx4/7. To verify this approach set of experimental ...

  1. Twisting Fluorescence through Extrinsic Chiral Antennas.

    Science.gov (United States)

    Yan, Chen; Wang, Xiaolong; Raziman, T V; Martin, Olivier J F

    2017-03-22

    Plasmonic antennas and planar structures have been undergoing intensive developments in order to control the scattering and absorption of light. One specific class, extrinsic chiral surfaces, that does not possess 2-fold rotational symmetry exhibits strong asymmetric transmission for different circular polarizations under obliquely incident illumination. In this work, we show that the design of those surfaces can be optimized with complex multipolar resonances in order to twist the fluorescence emission from nearby molecules. While this emission is usually dipolar and linearly polarized, the interaction with these resonances twists it into a multipolar radiation pattern with opposite helicity in different directions. The proposed structure maximizes this effect and provides control over the polarization of light. Splitting of left- and right-handed circularly polarized light is experimentally obtained in the backward direction. These results highlight the intricate interplay between the near-field absorption and the far-field scattering of a plasmonic nanostructure and are further used for modifying the emission of incoherent quantum sources. Our finding can potentially lead to the development of polarization- and angle-resolved ultracompact optical devices.

  2. The HRCT features of extrinsic allergic alveolitis.

    Science.gov (United States)

    Hartman, Thomas E

    2003-08-01

    Exposure to organic dusts can produce an immune-mediated inflammatory response in sensitized individuals. The pulmonary disease caused by this response has been called extrinsic allergic alveolitis (EAA) or hypersensitivity pneumonitis. The clinical phases associated with this process have been termed acute, subacute, and chronic. There are corresponding imaging findings that are characteristic of each of these phases, although there is some overlap between the phases. The acute phase is characterized by confluent opacities that may mimic infection or edema. The subacute phase is characterized by centrilobular nodules, areas of ground-glass attenuation, a mosaic perfusion pattern, and air trapping on expiratory imaging. The chronic phase is characterized by subpleural irregular linear opacities with associated architectural distortion. Honeycombing may sometimes also be present. In the acute and subacute phases, the disease is predominantly in the lower lungs, whereas in chronic EAA the findings are predominant in the mid to upper lungs. Although the high-resolution computed tomography findings individually are nonspecific, the combination of the findings coupled with the distribution of the findings can often narrow the differential or allow a presumptive diagnosis of EAA to be made.

  3. Hydrogen production by draTGB hupL double mutant of Rhodospirillum rubrum under different light conditions

    Institute of Scientific and Technical Information of China (English)

    ZHU Ruiyan; WANG Di; ZHANG Yaoping; LI Jilun

    2006-01-01

    To increase H2 yield of Rhodospirillum rubrum in two-stage hydrogen production process,two deletion mutants were constructed. One is single mutant designated R. rubrum UR801 that deleted hupL gene encoding the large subunit of uptake hydrogenase, and the other is a double mutant designated R. rubrum UR805 lacked both draTGB encoding regulators for the activity of nitrogenase and hupL.Comparing H2 yields of two mutants with R. rubrum UR2 (wild type) and UR472 (△draTGB) under different light conditions, the results showed that the H2 yield of R. rubrum UR801 under continuous light is the highest (5700 mL of H2 per liter culture), and it is 1.56, 2.24 and 2.32-fold that of R. rubrum UR2,UR472 and UR805, respectively. However, the total H2 yield of R. rubrum UR805 in two-stage hydrogen production process is the highest (4303 mL/L), and it is 1.35, 1.21 and 1.04-fold that of R. rubrum UR2,UR801 and UR472, respectively. Thus, R. rubrum UR805 might be a valuable strain to produce a large amount of hydrogen in two-stage hydrogen production process.

  4. An exploratory investigation into the role of extrinsic factors in ...

    African Journals Online (AJOL)

    Seugnet

    extrinsic factors in consumer decision-making for interior soft ... buy, in a passive manner, what retailers have to offer. Instead, they .... one's self-concept: the consumption of interior prod- .... important influencing variable in consumer decision-.

  5. The effects of extrinsic rewards on children's intrinsic motivation

    OpenAIRE

    大槻, 千秋

    1981-01-01

    An experiment was conducted with preschool children to test whether a person's intrinsic motivation in an activity may be decreased by extrinsic salient rewards in Japan like in America. Children solved some jigsaw puzzles and received assorted candies, then they were observed how long they did other jigsaw puzzles. The results showed that the effects of extrinsic rewards on intrinsic motivation in an activity varied with the subject's social background. In uptown children's intrinsic motivat...

  6. The effects of extrinsic rewards on children's intrinsic motivation

    OpenAIRE

    大槻, 千秋

    1981-01-01

    An experiment was conducted with preschool children to test whether a person's intrinsic motivation in an activity may be decreased by extrinsic salient rewards in Japan like in America. Children solved some jigsaw puzzles and received assorted candies, then they were observed how long they did other jigsaw puzzles. The results showed that the effects of extrinsic rewards on intrinsic motivation in an activity varied with the subject's social background. In uptown children's intrinsic motivat...

  7. Extrinsic Rewards: An Adventist Curriculum Perspective for Classroom Management

    OpenAIRE

    Nadine A. Joseph

    2014-01-01

    Extrinsic rewards refer to gifts used as a form of motivation for students’ to attain an academic goal, or given when that particular goal is reached. Though the use of extrinsic rewards have been proven to have some impact on’ behavior change, such as academic performance, the absence of rewards can cause students’ to revert to the initial unwanted behavior. Consequently, the curricula focus in the Adventist classroom should address the deeper issues that affect behavior and implement the us...

  8. 二硼化锆陶瓷增韧技术的研究进展%Research and Development of Toughening Technologies of Zirconium Diboride Ceramics

    Institute of Scientific and Technical Information of China (English)

    冯伦; 王海龙; 范冰冰; 陈建宝; 许红亮; 陈德良; 卢红霞; 张锐

    2011-01-01

    本文介绍了近年来二硼化锆陶瓷的增韧技术及其机制,包括弥散颗粒增韧、不同长径比相(晶须、纤维、晶片、碳纳米管等)增韧、ZrO2相变增韧、仿生结构增韧、原位反应增韧、晶须和颗粒协同增韧;展望了二硼化锆陶瓷增韧技术的未来发展趋势.%This paper reviews recent toughening technologies and toughening mechanisms of zirconium diboride ceramics. These technologies include dispersed particles toughening, different aspect ratio phases (whiskers、chopped fibers,,platelets.,carbon nano-tubes et al) toughening, zirconia transformation toughening, biomimetic structure toughening, in-situ reaction toughening, SiC whiskers and SiC particles combined toughening. Futhermore, the future development of toughening technology of zirconium diboride ceramics is prospected.

  9. Mechanical behaviors of hyberbranched epoxy toughened bisphenol F epoxy resin for cryogenic applications

    Science.gov (United States)

    Li, Jingwen; Wu, Zhixiong; Huang, Chuanjun; Huang, Rongjin; Li, Laifeng

    2014-01-01

    Epoxy resins have been widely employed in cryogenic engineering fields. In this work, bisphenol F epoxy resin was modified by an aromatic polyester hyperbranched epoxy resin (HTDE-2). Mechanical behaviors of the modified epoxy resins in terms of tensile properties and impact property were studied at both room and cryogenic temperatures. Moreover, the toughening mechanism was discussed by fracture surface morphology analysis. The results demonstrated that, the mechanical properties of composites initially increased until reaches the maximum value with increasing the mass content of the HTDE-2, and then decreased at both room temperature (RT) and 77K. Especially, the impact strength at 77 K was improved 40.7% compared with the pure epoxy matrix when 10 wt% HTDE-2 was introduced. The findings suggest that the HTDE-2 will be an effective toughener for the brittle bisphenol F epoxy resin for cryogenic applications.

  10. The Mechanical Properties of Polyurethane Elastomer Reinforced and Toughened By CaSO4-Whisker

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    CaSO4 whisker reinforcing and toughening mechanisms for polyurethane elastomer were studied. The effects of dispersity of CaSO4 whisker and interfacial bonding state on reinforcement and toughness were discussed.The microanalyses showed that CaSO4 whisker reinforcing mechanism for polyurethane elastomer mainly was load transferring and its toughening mechanism involved crack deflection and whisker pullout.The results indicated that composites with 5%-10% CaSO4 whisker exhibited the best mechanical properties. Good bonding interface was formed between whisker and matrix after the surface of CaSO4 whisker was treated by silane coupling agent.The fairly improved strength and toughness are attributed to the better interfacial bonding state.

  11. Effects of Nickel Distribution on the Strengthening and Toughening of Alumina Ceramics

    Institute of Scientific and Technical Information of China (English)

    Mohamed. M. El-Sayed Seleman

    2008-01-01

    Three types of composite materials were designed and fabricated by hot pressing powder blends of alumina with 20 vol. pct nickel particles. The composites differ in the shape, size and distribution of the nickel particles.Composite microstructures are described and measurements of density, hardness, flexure strength, and fracture toughness are reported. The results showed that the fracture strength of the composite with dispersed nickel particles is higher than the other two composites (network microstructure and mixed microstructure) and the alumina matrix. For all the composites studied, tougher materials than the monolithic alumina were produced.The fracture toughness of the composite with a network microstructure is much higher than that of the other composites. The toughening mechanisms were described based on the observation of the fracture surfaces and the crack-particle interactions. Moreover, the parameters for microstructural tailoring of these materials have been deduced. The toughening of the produced composites was explained in light of the interracial bond strength.

  12. Synergistic toughening of graphene oxide-molybdenum disulfide-thermoplastic polyurethane ternary artificial nacre.

    Science.gov (United States)

    Wan, Sijie; Li, Yuchen; Peng, Jingsong; Hu, Han; Cheng, Qunfeng; Jiang, Lei

    2015-01-27

    Inspired by the ternary structure of natural nacre, robust ternary artificial nacre is constructed through synergistic toughening of graphene oxide (GO) and molybdenum disulfide (MoS2) nanosheets via a vacuum-assisted filtration self-assembly process. The synergistic toughening effect from high mechanical properties of GO and lubrication of MoS2 nanosheets is successfully demonstrated. Meanwhile, the artificial nacre shows high electrical conductivity. This approach for constructing robust artificial nacre by synergistic effect from GO and MoS2 provides a creative opportunity for designing and fabricating integrated artificial nacre in the near future, and this kind of ternary artificial nacre has great potential applications in aerospace, flexible supercapacitor electrodes, artificial muscle, and tissue engineering.

  13. 不同弹性体增韧聚甲醛的研究%Toughening of Polyoxymethylene with Different Elastomers

    Institute of Scientific and Technical Information of China (English)

    姚秀超; 朱勇飞; 吕通建; 李璐; 赵静; 吴树岭

    2013-01-01

    Polyoxymethylene (POM) was toughened with acrylic ester type elastomer (KT-28) and thermoplastic polyurethane (PUR-T) as toughening agent through melt blending,effects of the two toughening agents contents on melt flow rate (MFR),toughness and tensile strength of POM were studied.The results show that with content of KT-28 and PUR-T increasing,the MFR and tensile strength of POM decrease,instead,the notched impact strength and enelongation at break increase.The MFR of POM toughened by KT-28 is lower than that of POM toughened by PUR-T,which indicated that the compatibility of KT-28 and POM is better than that of PUR-T and POM.The notched impact strength and elongation at break of POM toughened by KT-28 are higher than those of POM toughened by PUR-T,meanwhile,the degradation effect of KT-28 on the tensile strength of POM is less than that of PUR-T when the mass fraction of toughening agent is below 12% and the price of KT-28 is lower than PUR-T,so it is a toughening agent with good toughening effect and low price for POM.%以丙烯酸酯类弹性体(KT-28)和热塑性聚氨酯(PUR-T)为增韧剂,通过熔融共混法对聚甲醛(POM)进行增韧改性,研究了这2种增韧剂含量对POM熔体流动速率(MFR)、韧性和拉伸强度的影响.结果表明,随KT-28和PUR-T含量的增加,POM的MFR和拉伸强度逐渐降低,缺口冲击强度和断裂伸长率逐渐升高;KT-28增韧POM的MFR低于PUR-T增韧POM,表明KT-28与POM的相容性比PUR-T更好;POM/KT-28的缺口冲击强度和断裂伸长率均高于POM/PUR-T,且当增韧荆质量分数低于12%时,KT-28对POM拉伸强度的劣化影响比PUR-T的小,同时KT-28具有比PUR-T更低的价格成本,是一种增韧效果好且价格低廉的POM增韧荆.

  14. Extrinsic value orientation and affective forecasting: overestimating the rewards, underestimating the costs.

    Science.gov (United States)

    Sheldon, Kennon M; Gunz, Alexander; Nichols, Charles P; Ferguson, Yuna

    2010-02-01

    We examined affective forecasting errors as a possible explanation of the perennial appeal of extrinsic values and goals. Study 1 found that although people relatively higher in extrinsic (money, fame, image) compared to intrinsic (growth, intimacy, community) value orientation (REVO) are less happy, they nevertheless believe that attaining extrinsic goals offers a strong potential route to happiness. Study 2's longitudinal experimental design randomly assigned participants to pursue either 3 extrinsic or 3 intrinsic goals over 4 weeks, and REVO again predicted stronger forecasts regarding extrinsic goals. However, not even extrinsically oriented participants gained well-being benefits from attaining extrinsic goals, whereas all participants tended to gain in happiness from attaining intrinsic goals. Study 3 showed that the effect of REVO on forecasts is mediated by extrinsic individuals' belief that extrinsic goals will satisfy autonomy and competence needs. It appears that some people overestimate the emotional benefits of achieving extrinsic goals, to their potential detriment.

  15. Mechanism of crumb toughening in bread-like products by microwave reheating.

    Science.gov (United States)

    Uzzan, Michael; Ramon, Ory; Kopelman, Ishaiahu J; Kesselman, Ellina; Mizrahi, Shimon

    2007-08-08

    Comparing breads reheated in conventional and microwave ovens revealed that the latter considerably toughens the crumb texture when internal boiling is induced. Moisture loss in itself has a relatively minor toughening effect. The major changes, caused by boiling, occur only in systems with starch concentration in excess of a threshold level of about 37% (wet basis). Substantially greater amounts of amylose are leached out of the granules in the case of sustained boiling during microwave heating, as compared to conventional oven heating. The free amylose solution is being "pushed" by the generated steam pressure toward the air-cell wall interface. A rich amylose phase is accumulated at that interface and over the granules. Upon cooling, the amylose undergoes rapid phase changes; thus, toughening is apparent in a relatively short time after heating. Minimizing the textural deleterious effects in microwave reheating of bread-like products should entail (a) preventing or minimizing internal boiling, (b) diluting of the starch concentration below the threshold level, (c) interfering with the amylose phase change by using complex forming agents.

  16. ON THE EFFECT OF NANO-PARTICLE CLUSTERING ON TOUGHENING OF NANO-COMPOSITE CERAMICS

    Institute of Scientific and Technical Information of China (English)

    董照旭; 方岱宁; 苏爱嘉

    2002-01-01

    In this paper, two and three-dimensional clustering models are developed to characterize the effect of nano-particle clustering on toughening of nanocomposite ceramics. It is found that crack pinning toughens the nano-composite ceramics because a higher stress intensity factor is needed for crack to propagate around or to pull-out the nano-particle. The nano-particle along the grain boundary steers the crack into the matrix grain due to the strong cohesion between the nanoparticle and the matrix. Since the fracture resistance of the grain boundary is lower than that of the grain lattice, the higher the probability of transgranular fracture induced by nano-particles, the tougher is the nano-composite. However, both crack pinning and transgranular fracture are affected by nano-particle clustering. Nanoparticle clustering, which increases with increasing volume fraction of nano-particles,leads to reduction of both the strength and toughness of the nano-composite ceramics. The larger the size of the clustered particle, and the more defects it contains, the easier it is for the crack to pass through the clustered particle, which means that the nano-particle clustering can reduce toughening induced by crack pinning and transgranular fracture. The theoretical prediction, based on the combination of the three mechanisms of nano-particles, is in agreement with the experimental data.

  17. Perfectionism and life aspirations in intrinsically and extrinsically religious individuals.

    Science.gov (United States)

    Steffen, Patrick R

    2014-08-01

    Religiosity is related to positive health and life satisfaction but the pathways through which this occurs have not been clearly delineated. The purpose of this study was to examine potential mediators of the relationships between intrinsic and extrinsic religiosity and negative affect and life satisfaction. Perfectionism and life aspirations are two possible pathways through which religious orientation is related to outcome. It was hypothesized that adaptive perfectionism and intrinsic life aspirations would act as mediators between intrinsic religiosity and negative affect and life satisfaction, and that maladaptive perfectionism and extrinsic life aspirations would act as mediators between the extrinsic religiosity and negative affect and life satisfaction. Two consecutive samples of religious college students (N = 540 and N = 485) completed measures of the Age Universal Religious Orientation Index, the Frost Multi-Dimensional Perfectionism Scale, the Aspiration Index, the Beck Depression Inventory-II, the Spielberger State-Trait Anxiety Inventory, and the Satisfaction with Life Scale. Intrinsic religiosity had a direct negative relationship with negative affect and positive relationship with life satisfaction. Contrary to the hypotheses, intrinsic religiosity had its strongest indirect effect via maladaptive perfectionism such that increased intrinsic religiosity was related to decreased maladaptive perfectionism which in turn lead to better negative affect and life satisfaction. Extrinsic religiosity was related to increased maladaptive perfectionism and thereby indirectly contributed to worse negative affect and life satisfaction. Interestingly, when the effects of maladaptive perfectionism were controlled, the direct effects of extrinsic religiosity were related to reduced negative affect and increased life satisfaction. Overall, the strongest mediator in this study of both intrinsic and extrinsic religiosity was maladaptive perfectionism, with intrinsic

  18. INTRINSIC AND EXTRINSIC MOTIVATION - AN INVESTIGATION OF PERFORMANCE CORRELATION

    Directory of Open Access Journals (Sweden)

    Abrudan Maria-Madela

    2011-07-01

    Full Text Available A series of research untaken in the last decade have revealed some interesting aspects regarding the effects of different types of motivation on performance. Among the researchers who have shown interest in this field we can number: Richard Ryan, Edward Deci, Sam Glucksberg, Dan Ariely, Robert Eisenhower, Linda Shanock, analysts from London School of Economics, and others. Their findings suggest that extrinsic incentives may have a negative impact on overall performance, but a general agreement in this respect has not been reached. In this paper we intend to shed some light upon the relationship between intrinsic and extrinsic motivation and performance. Experts define intrinsic motivation as being the execution of a task or activity because of the inherent satisfaction arising from it rather than due to some separate outcome. In contrast with intrinsic motivation, we speak of extrinsic motivation whenever an activity is done in order to attain some separable outcome. With the purpose of contributing to the clarification of the links between concepts, we initiated and conducted an explanatory research. The research is based on the analysis of the relations between the results obtained by third year students and their predominant type of motivation. For this, we formulated and tested four work hypotheses using a combination of quantitative methods (investigation and qualitative methods (focus group. After the validation of the questionnaires, the respondents were divided into four categories: intrinsically motivated, extrinsically motivated, both intrinsically and extrinsically motivated and unmotivated. To analyze the collected data, we made use of Excel and SPSS. Some of the primary conclusions of the research are as follows: as the average increases, the percent of individuals having both extrinsic and intrinsic motivation is decreasing; the highest percentage of unmotivated students is concentrated in the highest average category; Female

  19. Automated segmentation of cerebral vasculature with aneurysms in 3DRA and TOF-MRA using geodesic active regions: An evaluation study

    NARCIS (Netherlands)

    H. Bogunović; J.M. Pozo; M.C. Villa-Uriol; C.B.L.M. Majoie; R. van den Berg; H.A.F.G. van Andel; J.M. Macho; J. Blasco; L.S. Román; A.F. Frangi

    2011-01-01

    Purpose: To evaluate the suitability of an improved version of an automatic segmentation method based on geodesic active regions (GAR) for segmenting cerebral vasculature with aneurysms from 3D x-ray reconstruction angiography (3DRA) and time of flight magnetic resonance angiography (TOF-MRA) images

  20. Ternary complex formation between AmtB, GlnZ and the nitrogenase regulatory enzyme DraG reveals a novel facet of nitrogen regulation in bacteria.

    Science.gov (United States)

    Huergo, Luciano F; Merrick, Mike; Pedrosa, Fábio O; Chubatsu, Leda S; Araujo, Luíza M; Souza, Emanuel M

    2007-12-01

    Ammonium movement across biological membranes is facilitated by a class of ubiquitous channel proteins from the Amt/Rh family. Amt proteins have also been implicated in cellular responses to ammonium availability in many organisms. Ammonium sensing by Amt in bacteria is mediated by complex formation with cytosolic proteins of the P(II) family. In this study we have characterized in vitro complex formation between the AmtB and P(II) proteins (GlnB and GlnZ) from the diazotrophic plant-associative bacterium Azospirillum brasilense. AmtB-P(II) complex formation only occurred in the presence of adenine nucleotides and was sensitive to 2-oxoglutarate when Mg(2+) and ATP were present, but not when ATP was substituted by ADP. We have also shown in vitro complex formation between GlnZ and the nitrogenase regulatory enzyme DraG, which was stimulated by ADP. The stoichiometry of this complex was 1:1 (DraG monomer : GlnZ trimer). We have previously reported that in vivo high levels of extracellular ammonium cause DraG to be sequestered to the cell membrane in an AmtB and GlnZ-dependent manner. We now report the reconstitution of a ternary complex involving AmtB, GlnZ and DraG in vitro. Sequestration of a regulatory protein by the membrane-bound AmtB-P(II) complex defines a new regulatory role for Amt proteins in Prokaryotes.

  1. Introducing SummerTime: A package for high-precision computation of sums appearing in DRA1 method

    Science.gov (United States)

    Lee, Roman N.; Mingulov, Kirill T.

    2016-06-01

    We present the Mathematica package SummerTime for arbitrary-precision computation of sums appearing in the results of DRA method (Lee, 2010). So far these results include the following families of the integrals: 3-loop onshell massless vertices, 3-loop onshell mass operator type integrals, 4-loop QED-type tadpoles, 4-loop massless propagators (Lee et al., 2010; Lee and Smirnov, 2011; Lee et al., 2011, 2012). The package can be used for high-precision numerical computation of the expansion of the integrals from the above families around arbitrary space-time dimension. In addition, this package contains convenient tools for the calculation of multiple zeta values, harmonic polylogarithms and other transcendental numbers expressed in terms of nested sums with factorized summand.

  2. The distinct roles of anion transporters Slc26a3 (DRA) and Slc26a6 (PAT-1) in fluid and electrolyte absorption in the murine small intestine.

    Science.gov (United States)

    Xia, Weiliang; Yu, Qin; Riederer, Brigitte; Singh, Anurag Kumar; Engelhardt, Regina; Yeruva, Sunil; Song, Penghong; Tian, De-An; Soleiman, Manoocher; Seidler, Ursula

    2014-08-01

    The mixing of gastric and pancreatic juice subjects the jejunum to unique ionic conditions with high luminal CO2 tension and HCO3 − concentration. We investigated the role of the small intestinal apical anion exchangers PAT-1 (Slc26a6) and DRA (Slc26a3) in basal and CO2/HCO3 −-stimulated jejunal fluid absorption. Single pass perfusion of jejunal segments was performed in anaesthetised wild type (WT) as well as in mice deficient in DRA, PAT-1, Na+/H+ exchanger 3 (NHE3) or NHE2, and in carbonic anhydrase II (CAII). Unbuffered saline (pH 7.4) perfusion of WT jejunum resulted in fluid absorption and acidification of the effluent. DRA-deficient jejunum absorbed less fluid than WT, and acidified the effluent more strongly, consistent with its action as a Cl−/HCO3 − exchanger. PAT-1-deficient jejunum also absorbed less fluid but resulted in less effluent acidification. Switching the luminal solution to a 5 % CO2/HCO3 − buffered solution (pH 7.4), resulted in a decrease in jejunal enterocyte pHi in all genotypes, an increase in luminal surface pH and a strong increase in fluid absorption in a PAT-1- and NHE3- but not DRA-, CAII, or NHE2-dependent fashion. Even in the absence of luminal Cl−, luminal CO2/HCO3 − augmented fluid absorption in WT, CAII, NHE2- or DRA-deficient, but not in PAT-1- or NHE3-deficient mice, indicating the likelihood that PAT-1 serves to import HCO3 − and NHE3 serves to import Na+ under these circumstances. The results suggest that PAT-1 plays an important role in jejunal Na+HCO3 – reabsorption, while DRA absorbs Cl− and exports HCO3 − in a partly CAII-dependent fashion. Both PAT-1 and DRA significantly contribute to intestinal fluid absorption and enterocyte acid/base balance but are activated by different ion gradients.

  3. Extrinsic versus intrinsic hand muscle dominance in finger flexion.

    Science.gov (United States)

    Al-Sukaini, A; Singh, H P; Dias, J J

    2016-05-01

    This study aims to identify the patterns of dominance of extrinsic or intrinsic muscles in finger flexion during initiation of finger curl and mid-finger flexion. We recorded 82 hands of healthy individuals (18-74 years) while flexing their fingers and tracked the finger joint angles of the little finger using video motion tracking. A total of 57 hands (69.5%) were classified as extrinsic dominant, where the finger flexion was initiated and maintained at proximal interphalangeal and distal interphalangeal joints. A total of 25 (30.5%) were classified as intrinsic dominant, where the finger flexion was initiated and maintained at the metacarpophalangeal joint. The distribution of age, sex, dominance, handedness and body mass index was similar in the two groups. This knowledge may allow clinicians to develop more efficient rehabilitation regimes, since intrinsic dominant individuals would not initiate extrinsic muscle contraction till later in finger flexion, and might therefore be allowed limited early active motion. For extrinsic dominant individuals, by contrast, initial contraction of extrinsic muscles would place increased stress on the tendon repair site if early motion were permitted. © The Author(s) 2016.

  4. The effect of extrinsic noise on cellular decision making

    Science.gov (United States)

    Roberts, Elijah; Assaf, Michael; Luthey-Schulten, Zaida; Goldenfeld, Nigel

    2013-03-01

    Many cellular processes are not deterministic, i.e., genetically identical cells can display different phenotypic behavior even in identical environments. Such processes involve cellular decision making, in which individual cells randomly make choices determining their fate. One view is that the stochastic nature of cellular decision making is due to noise present in the biomolecular interaction networks. Most previous work has focused on the role of intrinsic noise of these networks. Yet, especially in the high copy-number regime, extrinsic noise may be much more significant, likely governing the overall dynamics. Here we develop a theoretical framework describing the combined effect of intrinsic and extrinsic noise on the stochastic dynamics of genetic switches responsible for cellular decision making. We do so by devising a semi-classical theory accounting for extrinsic noise as an effective species. Our theory, corroborated by extensive Monte-Carlo simulations, is tested on a simple bistable self-regulating gene model, and is then generalized to gain insight on the behavior of the lac genetic switch under extrinsic noise. We show that extrinsic noise not only significantly lowers the escape time from a phenotypic state, but can fundamentally change the actual escape process.

  5. Mechanical and thermal studies of unsaturated polyester-toughened epoxy composites filled with amine-functionalized nanosilica

    Science.gov (United States)

    Jaya Vinse Ruban, Y.; Ginil Mon, S.; Vetha Roy, D.

    2013-02-01

    The inter-crosslinking networks of unsaturated polyester (UP)-toughened epoxy-nanosilica hybrid nanocomposites have been developed. Epoxy resin was toughened with 5 and 10% (by wt) of unsaturated polyester using benzoyl peroxide as radical initiator and 4,4'-diaminodiphenylmethane (DDM) as a curing agent at appropriate condition, and the resulting product was identified by FT-IR spectra. Unsaturated polyester-toughened epoxy system (10%) was further filled with 1, 3, 5 and 7% (by wt) of amine-functionalized nanosilica particles prepared by sol-gel method. Modified nanosilica-filled hybrid UP-epoxy matrices developed in the form of casting were characterized for their thermal, mechanical properties and water absorption capacity according to ASTM standards. The degree of dispersion of nanosilica in the matrices was investigated by SEM technique. Mechanical testing data indicate that the introduction of UP into epoxy resin has improved the impact strength. Significant improvement in the flexural properties, tensile properties and impact strength were observed in the UP-epoxy blends with increase in the percentage of amine-modified nanosilica particles. The T g value decreases with UP toughening and increases with concentration of modified nanosilica on the UP-epoxy matrix. The water absorption behavior is found to decrease with UP toughening and concentration of modified nanosilica on the UP-epoxy matrix.

  6. Extrinsic Motivation Index: A New Tool for Managing Labor Productivity

    Directory of Open Access Journals (Sweden)

    Berumen, S.A.

    2016-07-01

    Full Text Available The objective of this paper is to provide a tool of practical significance for HR managers and firm executives. This tool, which is called Extrinsic Motivation Index (EMI, is meant to measure the extrinsic motivation of employees. By measuring employees' extrinsic motivation, managers are able to track job satisfaction and, subsequently, implement measures aiming both to raise job satisfaction and to improve organizational commitment. In order to test the validity of the model, we apply the EMI to Faculty members at Spanish and German universities. We also carry out simulation experiments in order to to address all possible situations an organization most probably will have to deal with. The results point out significant differences in the level of motivation and commitment of Faculty members. Additionally, the analysis shows several ways in which an organization may manage job satisfaction issues according to on its level of resources.

  7. Intrinsic and Extrinsic Spin Hall Effects of Dirac Electrons

    Science.gov (United States)

    Fukazawa, Takaaki; Kohno, Hiroshi; Fujimoto, Junji

    2017-09-01

    We investigate the spin Hall effect (SHE) of electrons described by the Dirac equation, which is used as an effective model near the L-points in bismuth. By considering short-range nonmagnetic impurities, we calculate the extrinsic as well as intrinsic contributions on an equal footing. The vertex corrections are taken into account within the ladder type and the so-called skew-scattering type. The intrinsic SHE which we obtain is consistent with that of Fuseya et al. [https://doi.org/10.1143/JPSJ.81.093704" xlink:type="simple">J. Phys. Soc. Jpn. 81, 093704 (2012)]. It is found that the extrinsic contribution dominates the intrinsic one when the system is metallic. The extrinsic SHE due to the skew scattering is proportional to Δ/niu, where 2Δ is the band gap, ni is the impurity concentration, and u is the strength of the impurity potential.

  8. Intrinsic and extrinsic motivation for stereotypic and repetitive behavior.

    Science.gov (United States)

    Joosten, Annette V; Bundy, Anita C; Einfeld, Stewart L

    2009-03-01

    This study provides evidence for intrinsic and extrinsic motivators for stereotypical and repetitive behavior in children with autism and intellectual disability and children with intellectual disability alone. We modified the Motivation Assessment Scale (MAS) (1988b); dividing it into intrinsic and extrinsic measures and adding items to assess anxiety as an intrinsic motivator. Rasch analysis of data from 279 MASs (74 children) revealed that the items formed two unidimensional scales. Anxiety was a more likely intrinsic motivator than sensory seeking for children with dual diagnoses; the reverse was true for children with intellectual disability only. Escape and gaining a tangible object were the most common extrinsic motivators for those with dual diagnoses and attention and escape for children with intellectual disability.

  9. Extrinsic allergic alveolitis with an atypical immune expression.

    Science.gov (United States)

    Costa, Teresa; Rodrigues, Cidália; Arrobas, Ana

    2009-01-01

    Extrinsic allergic alveolitis and sarcoidosis are two granulomatosis of the lung characterized by non- -necrotizing granuloma. Both have typical bronchoalveolar lavage immunology, with opposite CD4/CD8 relation. However, sarcoidosis does not have such well defined etiology as extrinsic allergic alveolitis. The authors present two cases with similar clinical course, imagiology, lung function and immunology, although they both had an histology that was not concordant with the bronchoalveolar lavage, and with the peculiarity of being two elements of the same family, co -inhabitants and with a clinical presentation only a few weeks apart.

  10. CONSUMER EVALUATIONS OF BEAUTIFICATION PRODUCTS: EFFECTS OF EXTRINSIC CUES

    Directory of Open Access Journals (Sweden)

    Md. Humayun Kabir Chowdhury

    2006-01-01

    Full Text Available This study investigates the influence of extrinsic cues, i.e. brand image, perceived price, perceived quality, and perceived country of origin on consumers' evaluative judgments for beautification products. Multi-item measures were used for data collection. Resultsrevealed that three extrinsic cues: brand image, perceived quality, and perceived country of origin have positive and significant influence on consumers' brand evaluation of beautification brands. Only perceived price has shown no such influence on consumers' brand evaluation. Finally, unanswered questions and future researchdirections are presented.

  11. Intrinsic and extrinsic motivation and intention to breast-feed.

    Science.gov (United States)

    Wells, Kristen J; Thompson, Nancy J; Kloeblen-Tarver, Amy S

    2002-01-01

    To examine the feasibility of using the cognitive evaluation theory to examine pregnant women's intention to breast-feed. A questionnaire designed to measure intrinsic and extrinsic motivation was administered to 228 pregnant women. Results provide evidence for reliability and validity of the revised instrument in this population. A factor analysis suggests the instrument measures 2 types of intrinsic motivation, one type of extrinsic motivation, and motivation related to the baby. The instrument distinguished differences in motivation between women who intend to breast-feed and those who intend to formula feed. This study helps elucidate motivational factors involved in infant-feeding decisions.

  12. Influence of air pollution on extrinsic childhood asthma

    Energy Technology Data Exchange (ETDEWEB)

    Berciano, F.A.; Dominguez, J.; Alvarez, F.V.

    1989-02-01

    A crossed comparative study was done with 248 extrinsic asthmatic children living either in polluted or non-polluted areas (mean emission per year of sedimentary material greater than or less than 300 mg/m2/day, respectively) to establish the influence of air pollution on childhood extrinsic asthma. The mean number of wheezing crises per year was significantly higher for the children living in polluted areas (10.4 versus 7.69). In addition, incidence of severe asthma (types II, III, and IV) in children living in polluted areas was markedly increased whereas the slight form of asthma (type I) was more frequent in children living in non-polluted areas. No correlation, however, between the wheezing episodes and levels of atmospheric contaminants (fumes and SO/sub 2/) was detected when a group of 84 extrinsic asthmatic children living in polluted areas was studied longitudinally for a year. The data indicate that air pollution, as an isolated agent, plays a transient role in the appearance of wheezing episodes in subjects with extrinsic asthma. Results also suggest that the air pollution may potentiate wheezing episodes via alternative mechanisms.

  13. On the isoperimetric rigidity of extrinsic minimal balls

    DEFF Research Database (Denmark)

    Markvorsen, Steen; Palmer, V.

    2003-01-01

    We consider an m-dimensional minimal submanifold P and a metric R-sphere in the Euclidean space R-n. If the sphere has its center p on P, then it will cut out a well defined connected component of P which contains this center point. We call this connected component an extrinsic minimal R-ball of ...

  14. The role of time scales in extrinsic noise propagation

    Science.gov (United States)

    Iyer-Biswas, Srividya; Pedraza, Juan Manuel; Jayaprakash, C.

    2009-03-01

    Cell-to cell variability in the number of proteins has been studied extensively experimentally. There are many sources of this stochastic variability or noise that can be classified as intrinsic, due to the stochasticity of chemical reactions and extrinsic, due to environmental differences. The different stages in the production of proteins in response to a stimulus, the signaling cascade before transcription, transcription, and translation are characterized by different time scales. We analyze how these time scales determine the effect of the reactions at each stage on different sources of noise. For example, even if intrinsic noise dominates the fluctuations in mRNA number, for typical degradation rates, extrinsic noise can dominate corresponding protein number fluctuations. Such results are important in determining the importance of intrinsic noise at earlier stages of a genetic network on the products of subsequent stages. We examine cases in which the dynamics of the extrinsic noise can lead to differences from cases in which extrinsic noise arises from static (in time) cell-to-cell variations. We will interpret the experiments of Pedraza et al*. in the light of these results. *J. M. Pedraza et al, Science 25 March 2005:Vol. 307. no. 5717, pp. 1965 - 1969.

  15. Intrinsic and extrinsic contributions to stochasticity in gene expression

    Science.gov (United States)

    Swain, Peter S.; Elowitz, Michael B.; Siggia, Eric D.

    2002-10-01

    Gene expression is a stochastic, or "noisy," process. This noise comes about in two ways. The inherent stochasticity of biochemical processes such as transcription and translation generates "intrinsic" noise. In addition, fluctuations in the amounts or states of other cellular components lead indirectly to variation in the expression of a particular gene and thus represent "extrinsic" noise. Here, we show how the total variation in the level of expression of a given gene can be decomposed into its intrinsic and extrinsic components. We demonstrate theoretically that simultaneous measurement of two identical genes per cell enables discrimination of these two types of noise. Analytic expressions for intrinsic noise are given for a model that involves all the major steps in transcription and translation. These expressions give the sensitivity to various parameters, quantify the deviation from Poisson statistics, and provide a way of fitting experiment. Transcription dominates the intrinsic noise when the average number of proteins made per mRNA transcript is greater than 2. Below this number, translational effects also become important. Gene replication and cell division, included in the model, cause protein numbers to tend to a limit cycle. We calculate a general form for the extrinsic noise and illustrate it with the particular case of a single fluctuating extrinsic variablea repressor protein, which acts on the gene of interest. All results are confirmed by stochastic simulation using plausible parameters for Escherichia coli.

  16. A note on optical activity and extrinsic chirality

    CERN Document Server

    Arteaga, Oriol

    2015-01-01

    It has been assumed that optical activity can be measured by illuminating alternatively a material with left- and right- handed circular polarized light and analyzing the differential response. This simple and intuitive approach is in general incorrect, and has led to misleading idea that extrinsic chirality involves optical activity.

  17. VOL 6. NO. 1 2015 EXTRINSIC FACTORS THAT AFFECT ...

    African Journals Online (AJOL)

    Frederick Iraki

    The general objective of this study was to identify the extrinsic factors affect employee ... individual mechanisms that directly affect job performance in an organization(Colquitt, ... Benjamin (2010) posits that fringe benefits are significant and positive ... Mouly (2009) asserts that questionnaires add value to research because.

  18. Extrinsic Reinforcement in the Classroom: Bribery or Best Practice

    Science.gov (United States)

    Akin-Little, K. Angeleque; Eckert, Tanya L.; Lovett, Benjamin J.; Little, Steven G.

    2004-01-01

    The debate over the effects of the use of extrinsic reinforcement in classrooms, businesses, and societal settings has been occurring for over 30 years. Some theorists have cautioned against the use of reward, whereas others have found little, if any, detrimental effect. This article examines the debate with an emphasis on data-based findings. The…

  19. The Effects of Extrinsic Reinforcement on Intrinsic Motivation.

    Science.gov (United States)

    Blocker, Richard A.; Edwards, R. P.

    1982-01-01

    Discusses the role of extrinsic reinforcement in intrinsic motivation in cognitive attribution theory. Concludes that cognitive attribution theory lacks parsimony, in that extant reinforcement analysis can account for undermining with equal facility. Suggests undermining is of little significance due to its elusive and transient impact on operant…

  20. Extrinsic allergic alveolitis after exposure to the yeast Rhodotorula rubra.

    Science.gov (United States)

    Siersted, H C; Gravesen, S

    1993-05-01

    A case of extrinsic allergic alveolitis following exposure to the red yeast Rhodotorula rubra is reported--to our knowledge, for the first time. Extensive growth of the yeast in the patient's environment was demonstrated, explaining an elevated titer of Rhodotorula-specific precipitating antibodies in his serum. A bronchial provocation test confirmed the diagnosis.

  1. Visible Spectrum Circular Dichroism in Extrinsic Chirality Metamaterials

    CERN Document Server

    Lee, Seoungjun; Feng, Cheng; Jiao, Jiao; Khan, Ashfaq; Li, Lin

    2012-01-01

    We present the new planar extrinsic chirality metamaterial (ECM) design that manifests giant circular dichroism (CD) in the visible spectrum range rather than usual near-infrared and terahertz range. Effects of incident beam angles and meta-molecules unit sizes on the CD spectrums were theoretically analyzed; Physical mechanism was illustrated in new figures of asymmetrical current excitation in neighboring unit cells.

  2. The Impact of Extrinsic Demographic Factors on Cantonese Speech Acquisition

    Science.gov (United States)

    To, Carol K. S.; Cheung, Pamela S. P.; McLeod, Sharynne

    2013-01-01

    This study modeled the associations between extrinsic demographic factors and children's speech acquisition in Hong Kong Cantonese. The speech of 937 Cantonese-speaking children aged 2;4 to 6;7 in Hong Kong was assessed using a standardized speech test. Demographic information regarding household income, paternal education, maternal education,…

  3. The Effects of Extrinsic Rewards on Admissions Counselors' Performance

    Science.gov (United States)

    Gardner-Engel, Miriam

    2010-01-01

    This study examines the best ways to motivate college admissions counselors. A review of literature revealed multiple perspectives on intrinsic and extrinsic as well as tangible and intangible rewards. Primary research was designed to examine the impact of tangible rewards and verbal reinforcements with a convenience sample of nine college…

  4. Extrinsic Rewards and Intrinsic Motivation in Education: Reconsidered Once Again.

    Science.gov (United States)

    Deci, Edward L.; Koestner, Richard; Ryan, Richard M.

    2001-01-01

    Reviews the results of a meta analysis (E. Deci, R. Koestner, and R. Ryan, 1999) that shows that tangible extrinsic rewards do have a substantial undermining effect on intrinsic motivation. Discusses results, which support cognitive evaluation theory, in terms of their relevance for educational practice. (SLD)

  5. Extrinsic and Intrinsic Motivation at 30: Unresolved Scientific Issues

    Science.gov (United States)

    Reiss, Steven

    2005-01-01

    The undermining effect of extrinsic reward on intrinsic motivation remains unproven. The key unresolved issues are construct invalidity (all four definitions are unproved and two are illogical); measurement unreliability (the free-choice measure requires unreliable, subjective judgments to infer intrinsic motivation); inadequate experimental…

  6. Extrinsic Rewards and Intrinsic Motivation in Education: Reconsidered Once Again.

    Science.gov (United States)

    Deci, Edward L.; Koestner, Richard; Ryan, Richard M.

    2001-01-01

    Reviews the results of a meta analysis (E. Deci, R. Koestner, and R. Ryan, 1999) that shows that tangible extrinsic rewards do have a substantial undermining effect on intrinsic motivation. Discusses results, which support cognitive evaluation theory, in terms of their relevance for educational practice. (SLD)

  7. Extrinsic and Intrinsic Motivation at 30: Unresolved Scientific Issues

    Science.gov (United States)

    Reiss, Steven

    2005-01-01

    The undermining effect of extrinsic reward on intrinsic motivation remains unproven. The key unresolved issues are construct invalidity (all four definitions are unproved and two are illogical); measurement unreliability (the free-choice measure requires unreliable, subjective judgments to infer intrinsic motivation); inadequate experimental…

  8. From matrix nano- and micro-phase tougheners to composite macro-properties.

    Science.gov (United States)

    Kinloch, A J; Taylor, A C; Techapaitoon, M; Teo, W S; Sprenger, S

    2016-07-13

    In this paper, firstly, the morphology and toughness of a range of bulk epoxy polymers, which incorporate a second phase of well-dispersed silica nanoparticles and/or rubber microparticles, have been determined. Secondly, the macro-properties of natural-fibre reinforced-plastic (NFRP) composites based upon these epoxy polymers have been ascertained, using (i) unidirectional flax fibres or (ii) regenerated-cellulose fibres in the architecture of a plain-woven fabric. Thirdly, the toughening mechanisms which are induced in these materials by the presence of the silica nanoparticles, the rubber microparticles and the natural fibres have been identified. Finally, the values of the toughness of the bulk epoxy polymers and corresponding NFRPs have been quantitatively modelled. The increased toughness recorded for the bulk epoxy polymer due to the presence of the silica nanoparticles and/or rubber microparticles was indeed typically transferred to the NFRP composites when using such epoxies as the matrices for the fibres. Thus, the important role that may be played by modifications to the epoxy matrices in order to increase the toughness of the composites was very clearly demonstrated by these results. However, notwithstanding, the toughening mechanisms induced by the fibres were essentially responsible for the very high toughnesses of the NFRP composites, compared with the bulk epoxy polymers. The modelling studies successfully predicted the values of toughness of the bulk epoxy polymers and of the NFRP composites. These studies also quantified the extent to which each toughening mechanism, induced by the second-phase nano- and microparticles and the natural fibres, contributed to the overall values of toughness of the materials. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'.

  9. Thermal shock behavior of toughened gadolinium zirconate/YSZ double-ceramic-layered thermal barrier coating

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Xinghua, E-mail: xhzhong@mail.sic.ac.cn; Zhao, Huayu; Zhou, Xiaming; Liu, Chenguang; Wang, Liang; Shao, Fang; Yang, Kai; Tao, Shunyan; Ding, Chuanxian

    2014-04-01

    Highlights: • Gd{sub 2}Zr{sub 2}O{sub 7}/YSZ DCL thermal barrier coating was designed and fabricated. • The Gd{sub 2}Zr{sub 2}O{sub 7} top ceramic layer was toughened by addition of nanostructured 3YSZ. • Remarkable improvement in thermal shock resistance of the DCL coating was achieved. - Abstract: Double-ceramic-layered (DCL) thermal barrier coating system comprising of toughened Gadolinium zirconate (Gd{sub 2}Zr{sub 2}O{sub 7}, GZ) as the top ceramic layer and 4.5 mol% Y{sub 2}O{sub 3} partially-stabilized ZrO{sub 2} (4.5YSZ) as the bottom ceramic layer was fabricated by plasma spraying and thermal shock behavior of the DCL coating was investigated. The GZ top ceramic layer was toughened by addition of nanostructured 3 mol% Y{sub 2}O{sub 3} partially-stabilized ZrO{sub 2} (3YSZ) to improve fracture toughness of the matrix. The thermal shock resistance of the DCL coating was enhanced significantly compared to that of single-ceramic-layered (SCL) GZ-3YSZ composite coating, which is believed to be primarily attributed to the two factors: (i) the increase in fracture toughness of the top ceramic layer by incorporating nanostructured YSZ particles and (ii) the improvement in strain tolerance through the utilization of 4.5YSZ as the bottom ceramic layer. In addition, the failure mechanisms are mainly attributed to the still low fracture toughness of the top ceramic layer and oxidation of the bond-coat.

  10. Thermomechanical response and toughening mechanisms of a carbon nano bead reinforced epoxy composite

    Energy Technology Data Exchange (ETDEWEB)

    Goyat, M.S., E-mail: goyatmanjeetsingh@gmail.com [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667 (India); Suresh, Sumit; Bahl, Sumit [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667 (India); Halder, Sudipta [Department of Mechanical Engineering, National Institute of Technology, Silchar, 788010, Assam (India); Ghosh, P.K. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667 (India)

    2015-09-15

    The current research on carbon nano beads (CNB) is focused on various applications such as high strength nanocomposites, electronic devices, lubricants, semiconductors, and high-performance batteries, etc. The commercial uses of CNB are yet juvenile for the market. Only limited results have been published so far on CNB reinforced polymers [1]. This study highlights the synthesis of uniform size, spherical CNB using chemical vapour deposition (CVD) method. The synthesized CNB are introduced into epoxy matrix by ultrasonic dual mode mixing route to produce CNB/epoxy nanocomposite. The CNB are characterized by X-ray diffraction, Energy dispersive X-ray analysis and field emission scanning electron microscope (FESEM). Morphology, thermal and mechanical properties of the CNB/epoxy nanocomposites is characterized by FESEM, Thermo-gravimetric analyzer and tensile and bending tests respectively. A noticeable improvement in thermal and mechanical properties of CNB reinforced epoxy matrix with low nanofiller content is observed. Several toughening mechanisms such as particle pull out, crack deflection, particle bridging, crack pinning, shear yielding or plastic deformation, and microcracking are identified. But, only the crack deflection, particle bridging and shear yielding or plastic deformations are recognized as the leading toughening mechanisms for CNB/epoxy nanocomposite. These results can be considered as symptomatic of a potential CNB espousal in new composites. - Highlights: • Synthesis of uniform size, spherical CNB using chemical vapour deposition method. • Fabrication of CNB/epoxy nanocomposites by ultrasonic dual mode mixing route. • Significant enhancement in thermomechanical properties of CNB/epoxy nanocomposite. • Main toughening mechanisms: Crack deflection, particle bridging and shear yielding.

  11. Nuclear Thermal Rocket/Vehicle Characteristics And Sensitivity Trades For NASA's Mars Design Reference Architecture (DRA) 5.0 Study

    Science.gov (United States)

    Borowski, Stanley K.; McCurdy, David R.; Packard, Thomas W.

    2009-01-01

    This paper summarizes Phase I and II analysis results from NASA's recent Mars DRA 5.0 study which re-examined mission, payload and transportation system requirements for a human Mars landing mission in the post-2030 timeframe. Nuclear thermal rocket (NTR) propulsion was again identified as the preferred in-space transportation system over chemical/aerobrake because of its higher specific impulse (I(sub sp)) capability, increased tolerance to payload mass growth and architecture changes, and lower total initial mass in low Earth orbit (IMLEO) which is important for reducing the number of Ares-V heavy lift launches and overall mission cost. DRA 5.0 features a long surface stay (approximately 500 days) split mission using separate cargo and crewed Mars transfer vehicles (MTVs). All vehicles utilize a common core propulsion stage with three 25 klbf composite fuel NERVA-derived NTR engines (T(sub ex) approximately 2650 - 2700 K, p(sub ch) approximately 1000 psia, epsilon approximately 300:1, I(sub sp) approximately 900 - 910 s, engine thrust-toweight ratio approximately 3.43) to perform all primary mission maneuvers. Two cargo flights, utilizing 1-way minimum energy trajectories, pre-deploy a cargo lander to the surface and a habitat lander into a 24-hour elliptical Mars parking orbit where it remains until the arrival of the crewed MTV during the next mission opportunity (approximately 26 months later). The cargo payload elements aerocapture (AC) into Mars orbit and are enclosed within a large triconicshaped aeroshell which functions as payload shroud during launch, then as an aerobrake and thermal protection system during Mars orbit capture and subsequent entry, descent and landing (EDL) on Mars. The all propulsive crewed MTV is a 0-gE vehicle design that utilizes a fast conjunction trajectory that allows approximately 6-7 month 1-way transit times to and from Mars. Four 12.5 kW(sub e) per 125 square meter rectangular photovoltaic arrays provide the crewed MTV with

  12. A reactive polystyrene-block-polyisoprene star copolymer as a toughening agent in an epoxy thermoset

    KAUST Repository

    Francis, Raju

    2015-12-29

    © 2015 Springer-Verlag Berlin Heidelberg A polystyrene-block-polyisoprene ((PS-b-PI)3) star polymer was synthesized by photochemical reversible addition fragmentation chain transfer (RAFT) polymerization. The obtained star polymer was epoxidized and used as a toughening agent in an epoxy thermoset. The incorporation of the epoxidized star polymer resulted in the formation of nanostructures and it was fixed by a crosslinking reaction. The formation of nanostructures in the thermosets follows the mechanism of reaction-induced microphase separation. The mechanical properties such as toughness and tensile strength were considerably increased due to the nanostructures formed by reactive blending.

  13. A novel chain-extended urea containing hyperbranched polymer used as toughening modifier for epoxy resin

    Institute of Scientific and Technical Information of China (English)

    LU Shao-rong; WEI Chun; YANG Xiao-wang

    2006-01-01

    A new kind of reactive toughening accelerator for epoxy resin,amine-teminated hyperbranched polymer (H2O-NMe2) was synthesized and characterized by FT-IR spectroscopy. Dynamic mechanical analysis (DMA) was used to study the glass transition temperature (Tg),loss factor (tanδ) and activation energy (Ea) by using multiplexing frequency. The results show that the Ea at glassy relaxation process of modified system is about 70-80 kJ/mol higher than that of unmodified system,and the high modulus and good thermal properties are still maintained.

  14. Biolubricant induced phase inversion and superhydrophobicity in rubber-toughened biopolymer/organoclay nanocomposites

    Science.gov (United States)

    Bayer, Ilker S.; Steele, Adam; Martorana, Philip; Loth, Eric; Robinson, Scott J.; Stevenson, Darren

    2009-08-01

    We present a simple technique to fabricate rubber-toughened biopolymer/organoclay nanocomposite coatings with highly water repellent surface wetting characteristics and strong adhesion to metal surfaces. The technique combines the principles of phase inversion and atomization of multicomponent polymer/organoclay suspensions containing a biolubricant as the nonsolvent. The biolubricant was a blend of cyclomethicone/dimethiconol oil with fruit kernel oils. The ternary system of cellulose nitrate/solvent/biolubricant was blended with rubber dispersed organoclay nanofluids. Natural, synthetic, and fluoroacrylic latex rubbers were used for the purpose. Self-cleaning superhydrophobic coatings were obtained from synthetic and fluoroacrylic rubbers whereas natural rubber containing formulations resulted in sticky superhydrophobic coatings.

  15. Space radiation effects on an elastomer-toughened epoxy-graphite composite

    Science.gov (United States)

    Sykes, G. F.; Slemp, W. S.

    1985-01-01

    An elastomer-toughened epoxy-graphite composite system (CE339/T300) was evaluated for its potential durability in the space radiation environment. The physical and chemical response of this system was characterized following exposure to radiation doses equivalent to 20 to 30 years in geosynchronous orbit using 1 MeV electrons. The results show that electrons generate extensive crosslinking and embrittlement of the matrix. This embrittlement results in chemical and mechanical property changes that would limit the service life of this epoxy system in some space structure applications.

  16. Carbon nanohoops as attractive toughening and lubricant agents in TiN porous films

    Science.gov (United States)

    Zheng, Jianyun; Ren, Xiaodong; Hao, Junying; Li, Ang; Liu, Weimin

    2017-01-01

    Hoop-shaped conjugated macrocycles (or carbon nanohoops) are eliciting significant interest from theoretical and synthetic scientists on account of their eminent physical and chemical properties. Herein, carbon nanohoops firstly fabricated by CH4 plasma treatment serve as toughening and lubricant agents in TiN porous films. The formation mechanism of carbon nanohoops is explained through a tandem Suzuki coupling/macrocyclization sequence of the charged multiple hydrocarbon molecules. The essential features of carbon nanohoops ensure that the TiN porous films with carbon nanohoops successfully possess flexible, hard, lubricant and antiwear effects.

  17. Photometry of Symbiotic Stars: an International Campaign 7b. CQ DRA (4Dra), YY Her, V 443 Her, BX Mon, AG Peg, AX Per, V 741 Per, FGG Sge, QW Sge, PU VUL

    Science.gov (United States)

    Hric, L.; Skopal, A.; Urban, Z.; Petrik, K.; Komzik, R.; Chochol, D.; Pribulla, T.; Niarchos, P.; Rovithis-Livaniou, H.; Rovithis, P.; Kaserkevich, V. S.; Shpychka, I. V.; Velic, Z.; Halevin, A. V.; Andronov, I. L.; Oksa, G.; Krticka, J.

    1996-10-01

    We present new observations of 10 symbiotic and symbiotic-like stars. The photoelectric UBV(R) observations cover the period 1994.75 to 1996.0. The CCD VRI, photographic and visual data also cover earlier times. The main results can be summarized as follows: (1) CQ Dra: The expected sudden brightening in the U color has been observed around JD 2 449 700. After then, the star's brightness declined smoothly in all three colors. (2) YY Her: The steady decline of the star's brightness in the V and R colors has been observed. (3) V443 Her: Variability with an amplitude of about 0.4 mag in the V color has been detected, while nothing similar has been found in the R and I. (4) AX Per: Our present data cover in part the primary minimum of the star. During the autumn of 1995, a small increase in all three colors has been observed. (5) PU Vul: A brightness minimum at JD 2 449 953, best pronounced in the V color, has been observed.

  18. Distinguishing subtypes of extrinsic motivation among people with mild to borderline intellectual disability

    NARCIS (Netherlands)

    Frielink, N.; Schuengel, C.; Embregts, P.J.C.M.

    Background According to self-determination theory, motivation is ordered in types, including amotivation, extrinsic motivation and intrinsic motivation. Self-determination theory defines four subtypes of extrinsic motivation: external motivation, introjected motivation, identified motivation and

  19. Photometric and spectroscopic observations of three rapidly rotating late-type stars: EY Dra, V374 Peg and GSC 02038-00293

    CERN Document Server

    Korhonen, H; Husarik, M; Mahajan, S; Szczygiel, D; Olah, K

    2010-01-01

    Here, BV(RI)c broad band photometry and intermediate resolution spectroscopy in Halpha region are presented for two rapidly rotating late-type stars: EY Dra and V374 Peg. For a third rapid rotator, GSC 02038-00293, intermediate resolution Halpha spectroscopy and low resolution spectroscopy are used for spectral classification and stellar parameter investigation of this poorly known object. The low resolution spectrum of GSC 02038-00293 clearly indicates that it is a K-type star. Its intermediate resolution spectrum can be best fitted with a model with Teff=4750K and vsini=90km/s, indicating a very rapidly rotating mid-K star. The Halpha line strength is variable, indicating changing chromospheric emission on GSC 02038-00293. In the case of EY Dra and V374 Peg, the stellar activity in the photosphere is investigated from the photometric observations, and in the chromosphere from the Halpha line. The enhanced chromospheric emission in EY Dra correlates well with the location of the photospheric active regions, ...

  20. Engagement in Classroom Learning: Creating Temporal Participation Incentives for Extrinsically Motivated Students through Bonus Credits

    Science.gov (United States)

    Rassuli, Ali

    2012-01-01

    Extrinsic inducements to adjust students' learning motivations have evolved within 2 opposing paradigms. Cognitive evaluation theories claim that controlling factors embedded in extrinsic rewards dissipate intrinsic aspirations. Behavioral theorists contend that if engagement is voluntary, extrinsic reinforcements enhance learning without ill…

  1. Engagement in Classroom Learning: Creating Temporal Participation Incentives for Extrinsically Motivated Students through Bonus Credits

    Science.gov (United States)

    Rassuli, Ali

    2012-01-01

    Extrinsic inducements to adjust students' learning motivations have evolved within 2 opposing paradigms. Cognitive evaluation theories claim that controlling factors embedded in extrinsic rewards dissipate intrinsic aspirations. Behavioral theorists contend that if engagement is voluntary, extrinsic reinforcements enhance learning without ill…

  2. In Vitro Fracture of Human Cortical Bone: Local Fracture Criteria and Toughening Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Nalla, R; Stolken, J; Kinney, J; Ritchie, R

    2004-08-18

    A micro-mechanistic understanding of bone fracture that encompasses how cracks interact with the underlying microstructure and defines their local failure mode is lacking, despite extensive research on the response of bone to a variety of factors like aging, loading, and/or disease. Micro-mechanical models for fracture incorporating such local failure criteria have been widely developed for metallic and ceramic materials systems; however, few such deliberations have been undertaken for the fracture of bone. In fact, although the fracture event in mineralized tissues such as bone is commonly believed to be locally strain controlled, until recently there has been little experimental evidence to support this widely held belief. In the present study, a series of in vitro experiments involving a double-notch bend test geometry are performed in order to shed further light on the nature of the local cracking events that precede catastrophic fracture in bone and to define their relationship to the microstructure. Specifically, crack-microstructure interactions are examined to determine the salient toughening mechanisms in human cortical bone and to characterize how these may affect the anisotropy in fracture properties. Based on preliminary micro-mechanical models of these processes, in particular crack deflection and uncracked ligament bridging, the relative importance of these toughening mechanisms is established.

  3. In situ inspection of inclusions in toughened glass panels of high-rise buildings

    Science.gov (United States)

    Li, Xiang; Fang, Zhong Ping; Reading, Ivan; Zhao, Liping; Chow, Siew Loong

    2005-04-01

    Transparent toughened glass panels are widely installed in high-rise buildings. There is a growing need for inspection to detect the presence of detrimental inclusions of Nickel Sulfide. These inclusions can cause toughened glass to shatter, possibly causing property damage or injury. Optical equipment has been developed which can detect the inclusions in-situ. Light is coupled into a glass panel and propagates along the glass by total internal reflection. An inclusion in the glass will cause the light to scatter. Once an inclusion is found, it will be observed at higher magnification and the detailed image will be processed. By the analysis of its key features, the inclusion type can be identified. The coupling medium is made of a transparent, soft and deformable material. The equipment can be attached to a glass panel by vacuum suction. The optical system can scan the whole glass panel with a constant force spring as anti-weight structure. The whole system is fast, convenient and highly effective. A patent has been filed for this apparatus.

  4. Preform-based toughening technology for RTMable high-temperature aerospace composites

    Institute of Scientific and Technical Information of China (English)

    YI XiaoSu; CHENG QunFeng; LIU ZhiZhen

    2012-01-01

    This article describes the efforts that led to the development of surface-loaded preforms that may be used to significantly improve the compression-after-impact strength of high-temperature composites and correspondingly to dramatically reduce the area of damage because of impact.Moreover,by matching the toughening polymer surface-loaded and design of the surface pattern,in-plane mechanical properties are unaffected or even improved over laminates made from the identical materials.The proprietary preforms,so-called ESTM-Fabrics,may be handled and infused with the high-temperature RTMable resins such as bismaleimide and polyimide in exactly the same manner as traditional fabrics without surface modification.The RTM conditions for the preform-based toughening is fully compatible with the traditional process procedure,making the technology cost-effective in production.This technology represents a key enabler for the use of low-cost RTM processes for high-temperature resins to supplant prepreg as the building-block material of choice for aeronautical composite structures.

  5. Micro-strain Evolution and Toughening Mechanisms in a Trimodal Al-Based Metal Matrix Composite

    Science.gov (United States)

    Zhang, Yuzheng; Topping, Troy D.; Yang, Hanry; Lavernia, Enrique J.; Schoenung, Julie M.; Nutt, Steven R.

    2015-03-01

    A trimodal metal matrix composite (MMC) based on AA (Al alloy) 5083 (Al-4.4Mg-0.7Mn-0.15Cr wt pct) was synthesized by cryomilling powders followed by compaction of blended powders and ceramic particles using two successive dual mode dynamic forgings. The microstructure consisted of 66.5 vol pct ultrafine grain (UFG) region, 30 vol pct coarse grain (CG) region and 3.5 vol pct reinforcing boron carbide particles. The microstructure imparted high-tensile yield strength (581 MPa) compared to a conventional AA 5083 (242 MPa) and enhanced ductility compared to 100 pct UFG Al MMC. The deformation behavior of the heterogeneous structure and the effects of CG regions on crack propagation were investigated using in situ scanning electron microscopy micro-tensile tests. The micro-strain evolution measured using digital image correlation showed early plastic strain localization in CG regions. Micro-voids due to the strain mismatch at CG/UFG interfaces were responsible for crack initiation. CG region toughening was realized by plasticity-induced crack closure and zone shielding of disconnected micro-cracks. However, these toughening mechanisms did not effectively suppress its brittle behavior. Further optimization of the CG distribution (spacing and morphology) is required to achieve toughness levels required for structural applications.

  6. Bisphenol-A epoxy resin reinforced and toughened by hyperbranched epoxy resin

    Institute of Scientific and Technical Information of China (English)

    ZHANG Daohong; JIA Demin; HUANG Xianbo

    2007-01-01

    The study on toughening and reinforcing of bisphenol-A epoxy resin is one of important developmental direction in the field.This paper reports a one-pot synthesis of aromatic polyester hyperbranched epoxy resin HTDE-2,an effect of HTDE-2 content on the mechanical and thermal performance of the bisphenol-A (E51)/HTDE-2 hybrid resin in detail.Fourier transform infrared (FT-IR) spectrometer,scanning electronic microscopy (SEM),differential scanning calorimetry (DSC),thermogravimetric analysis (TGA),dynamic mechanical thermal analysis (DMA) and molecular simulation technology are used to study the structure of HTDE-2,performance and toughening and reinforcing mechanism of the HTDE-2/E51 hybrid resin.It has been shown that the content of HTDE-2 has an important effect on the performance of the hybrid resin,and the performance of the HTDE-2/E51 blends has maximum with the increase in HTDE-2 content.The impact strength and fracture toughness of the hybrid resin with 9 wt-% HTDE-2 are almost 3.088 and 1.749 times of E51 performance respectively,furthermore,the tensile and flexural strength can also be enhanced about 20.7% and 14.2%,respectively.The glass transition temperature and thermal degradation temperature,however,are found to decrease to some extent.

  7. Data on a Laves phase intermetallic matrix composite in situ toughened by ductile precipitates.

    Science.gov (United States)

    Knowles, Alexander J; Bhowmik, Ayan; Purkayastha, Surajit; Jones, Nicholas G; Giuliani, Finn; Clegg, William J; Dye, David; Stone, Howard J

    2017-10-01

    The data presented in this article are related to the research article entitled "Laves phase intermetallic matrix composite in situ toughened by ductile precipitates" (Knowles et al.) [1]. The composite comprised a Fe2(Mo, Ti) matrix with bcc (Mo, Ti) precipitated laths produced in situ by an aging heat treatment, which was shown to confer a toughening effect (Knowles et al.) [1]. Here, details are given on a focused ion beam (FIB) slice and view experiment performed on the composite so as to determine that the 3D morphology of the bcc (Mo, Ti) precipitates were laths rather than needles. Scanning transmission electron microscopy (S(TEM)) micrographs of the microstructure as well as energy dispersive X-ray spectroscopy (EDX) maps are presented that identify the elemental partitioning between the C14 Laves matrix and the bcc laths, with Mo rejected from the matrix into laths. A TEM selected area diffraction pattern (SADP) and key is provided that was used to validate the orientation relation between the matrix and laths identified in (Knowles et al.) [1] along with details of the transformation matrix determined.

  8. Tribology of improved transformation-toughened ceramics-heat engine test

    Energy Technology Data Exchange (ETDEWEB)

    Lilley, E.; Rossi, G.A.; Pelletier, P.J. (Norton Co., Northboro, MA (United States). Advanced Ceramics Div.)

    1992-04-01

    A short term study has been carried out to evaluate the suitability as cam roller followers of three ceria zirconia toughened aluminas and two yttria stabilized tetragonal zirconias (YTZPs) previously enhanced in programs supported by ORNL. Norton Si{sub 3}N{sub 4} (NBD-100) was also included in this study as a reference material, because it was known from work at Northwestern University that Si{sub 3}N{sub 4} to experienced little or no wear in this application, and NBD-100 is currently a successful commercial bearing material. The tribological studies were subcontracted to the Torrington Company. They found that in cam roller follower simulated tests that there was essentially no wear after 1 hour and 5 hours of testing detectable by weighing and concluded that all of these ceramics are, therefore, candidate materials. Because of the minute amounts of wear it was not possible to identify the wear mechanism or to make any correlations with the other physical properties which were evaluated such as MOR, K{sub IC} hardness, density and grain size. Phase transformation during rolling has been of interest in the tribology of zirconia contain materials. The least stable of the ceria zirconia toughened aluminas resulted in as much as 33% monoclinic phase after testing whereas the yttria stabilized (TTZ) contained very little of this transformed phase. The results of this study show that oxide materials can now be considered as candidates for cam roller followers in heat engines.

  9. Fracture behavior of stainless steel-toughened NiAl composite plate

    Science.gov (United States)

    Nardone, Vincent C.

    1992-02-01

    Analysis of the tensile and fracture behavior of a composite system consisting of boron carbide particulate-reinforced NiAl with continuous 304 stainless steel toughening regions was performed. The composite was fabricated by extrusion, with the toughening regions extending along the length of the plate in the extrusion direction. Mechanical properties were determined as a function of orientation. Tensile testing revealed that the composite modulus varied only slightly as a function of testing direction, the strength was approximately 25 pct greater in the longitudinal relative to the transverse orientation, and the transverse failure strain was only 0.3 pct compared to values in excess of 10 pct for longitudinal testing. Notched Charpy impact testing indicated that the energy absorption values varied significantly as a function of specimen location and crack growth direction, ranging from 2 to 40 Joules. In addition, K IC values measured on subsize compact tension samples were found to range from 17 to 27 MPa ṡ m1/2. It was also established that the K max values determined from the maximum load measured during compact tension testing were similar to the K Q values calculated from instrumented notched Charpy impact testing. Finally, the fatigue crack growth characteristics of the composite were determined as a function of orientation.

  10. Generalized isoperimetric inequalities for extrinsic balls in minimal submanifolds

    DEFF Research Database (Denmark)

    Markvorsen, Steen; Palmer, Vicente

    2002-01-01

    The volume of an extrinsic ball in a minimal submanifold has a well defined lower bound when the ambient manifold has an upper bound on its sectional curvatures, see e.g. [2] and [10]. When this upper bound is non-positive, the second named author has shown an isoperimetric inequality for such do......The volume of an extrinsic ball in a minimal submanifold has a well defined lower bound when the ambient manifold has an upper bound on its sectional curvatures, see e.g. [2] and [10]. When this upper bound is non-positive, the second named author has shown an isoperimetric inequality...... for such domains, see [11]. This result again gives the comparison result for volumes alluded to above together with a characterization of the totally geodesic submanifolds of hyperbolic space forms. In the present paper we find a corresponding sharp isoperimetric inequality for minimal submanifolds in spaces...

  11. [Actualities in extrinsic allergic alveolities or hypersensitivity pneumonitis].

    Science.gov (United States)

    Ndiaye, M; Soumah, M; Sow, M L

    2007-01-01

    Significant advances have been noticed in the pathogenesis and the diagnosis of extrinsic allergic alveolitis during the last few years. Indeed the immune mechanism and the enabling conditions have been more precisely defined, the clinical stages and the diagnosis criterias clearly defined, new antigens incriminated and some etiological agents have been reclassified. The present pathogenic explanation insists on the type IV hypersensitivity reaction with sensitization of T lymphocytes, activation macrophages, the formation of IgG type antibodies and immune complexes, activation of complement and secretion of cytokines. The involvement of certain HLA classes (HLA2, DR3, DRB1, DQB1), interaction of genetics and environments factors, the role of infections agents and smoking have been demonstrated in several studies. The development of news clinical and biological diagnosis criteria have led the discovery of new extrinsic allergic alveolitis in the work places, a better knowledge of the prognostic elements and an appropriate adaptation of prevention measures.

  12. Implications on the cosmic coincidence by a dynamical extrinsic curvature

    CERN Document Server

    Capistrano, A J S

    2015-01-01

    In this work, we apply the smooth deformation concept in order to obtain a modification of Friedmann equations. It is shown that the cosmic coincidence can be at least alleviated using the dynamical properties of the extrinsic curvature. We investigate the transition from nucleosynthesis to the coincidence era obtaining a very small variation of the ratio $r=\\frac{\\rho_{m}}{\\rho_{ext}}$, that compares the matter energy density to extrinsic energy density, compatible with the known behavior of the deceleration parameter. We also show that the calculated "equivalence" redshift matches the transition redshift from a deceleration to accelerated phase and the coincidence ceases to be. The dynamics on $r$ is also studied based on Hubble parameter observations as the latest Baryons Acoustic Oscillations/Cosmic Microwave Background Radiation (BAO/CMBR) + SNIa.

  13. Spotlight on the diagnosis of extrinsic allergic alveolitis (hypersensitivity pneumonitis).

    Science.gov (United States)

    Baur, Xaver; Fischer, Axel; Budnik, Lygia T

    2015-01-01

    Repeated inhalative exposures to antigenic material from a variety of sources, mainly from moulds, thermophilic Actinomycetes, and avians, respectively, can induce immune responses with the clinical picture of extrinsic allergic alveolitis (EAA) or hypersensitivity pneumonitis. Delays of years or even decades till the diagnosis is made are not uncommon; frequent misdiagnoses include allergic asthma, COPD, recurrent flue and other infections. We provide here the state of the art references, a detailed case description and recommend a current diagnostics schema.

  14. Extrinsic allergic alveolitis with IgA deficiency.

    Science.gov (United States)

    Sennekamp, J; Morr, H; Behr, J

    2004-12-22

    Up to now only 3 cases of extrinsic allergic alveolitis (hypersensitivity pneumonitis) with IgA deficiency have been published worldwide. We had the opportunity to detect two additional cases which will be presented here. Summarizing all cases IgA deficiency is a risk factor for a severe course of the disease and an increased susceptibility to acquire allergic alveolitis by low dose antigen exposure.

  15. Mathematical Model of Extrinsic Blood Coagulation Cascade Dynamic System

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The blood coagulation system is very important to life. This paper presents a mathematical blood coagulation model for the extrinsic pathway. This model simulates clotting factor VIII, which plays an important role in the coagulation mechanism. The mathematical model is used to study the equilibrium stability, orbit structure, attractors and global stability behavior, with conclusions in accordance with the physiological phenomena. Moreover, the results provide information about blood related illnesses, which can be used for further study of the coagulation mechanism.

  16. Interactional Motivation in Artificial Systems: Between Extrinsic and Intrinsic Motivation

    OpenAIRE

    Georgeon, Olivier; Marshall, James; Gay, Simon

    2012-01-01

    International audience; This paper introduces Interactional Motivation (IM) as a way to implement self-motivation in artificial systems. An interactionally motivated agent selects behaviors for the sake of enacting the behavior itself rather than for the value of the behavior’s outcome. IM contrasts with extrinsic motivation by the fact that it defines the agent’s motivation independently from the environment’s state. Because IM does not refer to the environment’s states, we argue that IM is ...

  17. Extrinsic and intrinsic CPT asymmetries in neutrino oscillations

    Directory of Open Access Journals (Sweden)

    Tommy Ohlsson

    2015-04-01

    Full Text Available We reconsider the extrinsic and possible intrinsic CPT violation in neutrino oscillations, and point out an identity, i.e., AαβCP=AβαCPT+AαβT, among the CP, T, and CPT asymmetries in oscillations. For three-flavor oscillations in matter of constant density, the extrinsic CPT asymmetries AeeCPT, AeμCPT, AμeCPT, and AμμCPT caused by Earth matter effects have been calculated in the plane of different neutrino energies and baseline lengths. It is found that two analytical conditions can be implemented to describe the main structure of the contours of vanishing extrinsic CPT asymmetries. Finally, without assuming intrinsic CPT symmetry in the neutrino sector, we investigate the possibility to constrain the difference of the neutrino CP-violating phase δ and the antineutrino one δ¯ using a low-energy neutrino factory and the super-beam experiment ESSνSB. We find that |δ−δ¯|≲0.35π in the former case and |δ−δ¯|≲0.7π in the latter case can be achieved at the 3σ confidence level if δ=δ¯=π/2 is assumed.

  18. Mechanisms of rotator cuff tendinopathy: intrinsic, extrinsic, or both?

    Science.gov (United States)

    Seitz, Amee L; McClure, Philip W; Finucane, Sheryl; Boardman, N Douglas; Michener, Lori A

    2011-01-01

    The etiology of rotator cuff tendinopathy is multi-factorial, and has been attributed to both extrinsic and intrinsic mechanisms. Extrinsic factors that encroach upon the subacromial space and contribute to bursal side compression of the rotator cuff tendons include anatomical variants of the acromion, alterations in scapular or humeral kinematics, postural abnormalities, rotator cuff and scapular muscle performance deficits, and decreased extensibility of pectoralis minor or posterior shoulder. A unique extrinsic mechanism, internal impingement, is attributed to compression of the posterior articular surface of the tendons between the humeral head and glenoid and is not related to subacromial space narrowing. Intrinsic factors that contribute to rotator cuff tendon degradation with tensile/shear overload include alterations in biology, mechanical properties, morphology, and vascularity. The varied nature of these mechanisms indicates that rotator cuff tendinopathy is not a homogenous entity, and thus may require different treatment interventions. Treatment aimed at addressing mechanistic factors appears to be beneficial for patients with rotator cuff tendinopathy, however, not for all patients. Classification of rotator cuff tendinopathy into subgroups based on underlying mechanism may improve treatment outcomes.

  19. Are competition and extrinsic motivation reliable predictors of academic cheating?

    Directory of Open Access Journals (Sweden)

    Gábor eOrosz

    2013-02-01

    Full Text Available Previous studies suggest that extrinsic motivation and competition are reliable predictors of academic cheating. The aim of the present questionnaire study was to separate the effects of motivation- and competition-related variables on academic cheating by Hungarian high school students (N = 620, M = 264, F = 356. Structural equation modeling showed that intrinsic motivation has a negative effect, and amotivation has a positive indirect effect on self-reported academic cheating. In contrast, extrinsic motivation had no significant effect. Indirect positive influence on cheating, based on some characteristics of hypercompetition, was also found, whereas attitudes towards self-developmental competition had a mediated negative influence. Neither constructive nor destructive competitive classroom climate had a significant impact on academic dishonesty. Acceptance of cheating and guilt has significant and direct effect on self-reported cheating. In comparison with them, the effects of motivational and competition-related variables are relatively small, even negligible. These results suggest that extrinsic motivation and competition are not amongst the most reliable predictors of academic cheating behavior.

  20. Effects of empathic paraphrasing - Extrinsic emotion regulation in social conflict

    Directory of Open Access Journals (Sweden)

    Maria eSeehausen

    2012-11-01

    Full Text Available In the present study, we investigated the effects of empathic paraphrasing as an extrinsic emotion regulation technique in social conflict. We hypothesized that negative emotions elicited by social conflict can be regulated extrinsically in a conversation by a listener following the narrator’s perspective and verbally expressing cognitive empathy.20 participants were interviewed on an ongoing or recently self-experienced social conflict. The interviewer utilized ten standardized open questions inviting participants to describe their perception of the conflict. After each of the ten descriptions, the interviewer responded by either paraphrasing or taking notes (control condition. Valence ratings pertaining to the current emotional state were assessed during the interview along with psychophysiological and voice recordings.Participants reported feeling less negative after hearing the interviewer paraphrase what they had said. In addition, we found a lower sound intensity of participants' voices when answering to questions following a paraphrase. At the physiological level, skin conductance response, as well as heart rate, was higher during paraphrasing than during taking notes, while blood volume pulse amplitude was lower during paraphrasing, indicating higher autonomic arousal.The results show that demonstrating cognitive empathy through paraphrasing can extrinsically regulate negative emotion on a short-term basis. Paraphrasing led to enhanced autonomic activation in recipients, while at the same time influencing emotional valence in the direction of feeling better. A possible explanation for these results is that being treated in an empathic manner may stimulate a more intense emotion processing helping to transform and resolve the conflict.

  1. Extrinsic Calibration of Camera Networks Based on Pedestrians.

    Science.gov (United States)

    Guan, Junzhi; Deboeverie, Francis; Slembrouck, Maarten; Van Haerenborgh, Dirk; Van Cauwelaert, Dimitri; Veelaert, Peter; Philips, Wilfried

    2016-05-09

    In this paper, we propose a novel extrinsic calibration method for camera networks by analyzing tracks of pedestrians. First of all, we extract the center lines of walking persons by detecting their heads and feet in the camera images. We propose an easy and accurate method to estimate the 3D positions of the head and feet w.r.t. a local camera coordinate system from these center lines. We also propose a RANSAC-based orthogonal Procrustes approach to compute relative extrinsic parameters connecting the coordinate systems of cameras in a pairwise fashion. Finally, we refine the extrinsic calibration matrices using a method that minimizes the reprojection error. While existing state-of-the-art calibration methods explore epipolar geometry and use image positions directly, the proposed method first computes 3D positions per camera and then fuses the data. This results in simpler computations and a more flexible and accurate calibration method. Another advantage of our method is that it can also handle the case of persons walking along straight lines, which cannot be handled by most of the existing state-of-the-art calibration methods since all head and feet positions are co-planar. This situation often happens in real life.

  2. Are competition and extrinsic motivation reliable predictors of academic cheating?

    Science.gov (United States)

    Orosz, Gábor; Farkas, Dávid; Roland-Lévy, Christine

    2013-01-01

    Previous studies suggest that extrinsic motivation and competition are reliable predictors of academic cheating. The aim of the present questionnaire study was to separate the effects of motivation- and competition-related variables on academic cheating by Hungarian high school students (N = 620, M = 264, F = 356). Structural equation modeling showed that intrinsic motivation has a negative effect, and amotivation has a positive indirect effect on self-reported academic cheating. In contrast, extrinsic motivation had no significant effect. Indirect positive influence on cheating, based on some characteristics of hypercompetition, was also found, whereas attitudes toward self-developmental competition had a mediated negative influence. Neither constructive nor destructive competitive classroom climate had a significant impact on academic dishonesty. Acceptance of cheating and guilt has significant and direct effect on self-reported cheating. In comparison with them, the effects of motivational and competition-related variables are relatively small, even negligible. These results suggest that extrinsic motivation and competition are not amongst the most reliable predictors of academic cheating behavior.

  3. Stochastic synchronization of neuronal populations with intrinsic and extrinsic noise.

    KAUST Repository

    Bressloff, Paul C

    2011-05-03

    We extend the theory of noise-induced phase synchronization to the case of a neural master equation describing the stochastic dynamics of an ensemble of uncoupled neuronal population oscillators with intrinsic and extrinsic noise. The master equation formulation of stochastic neurodynamics represents the state of each population by the number of currently active neurons, and the state transitions are chosen so that deterministic Wilson-Cowan rate equations are recovered in the mean-field limit. We apply phase reduction and averaging methods to a corresponding Langevin approximation of the master equation in order to determine how intrinsic noise disrupts synchronization of the population oscillators driven by a common extrinsic noise source. We illustrate our analysis by considering one of the simplest networks known to generate limit cycle oscillations at the population level, namely, a pair of mutually coupled excitatory (E) and inhibitory (I) subpopulations. We show how the combination of intrinsic independent noise and extrinsic common noise can lead to clustering of the population oscillators due to the multiplicative nature of both noise sources under the Langevin approximation. Finally, we show how a similar analysis can be carried out for another simple population model that exhibits limit cycle oscillations in the deterministic limit, namely, a recurrent excitatory network with synaptic depression; inclusion of synaptic depression into the neural master equation now generates a stochastic hybrid system.

  4. Morphologic-anthropological investigations in tomb K93.12 at Dra' Abu el-Naga (Western Thebes, Egypt).

    Science.gov (United States)

    Lösch, Sandra; Moghaddam, Negahnaz; Paladin, Alice; Rummel, Ute; Hower-Tilmann, Estelle; Zink, Albert

    2014-01-01

    In this study we present the analysis of the human remains from tomb K93.12 in the Ancient Egyptian necropolis of Dra' Abu el-Naga, located opposite the modern city of Luxor in Upper Egypt on the western bank of the Nile. Archaeological findings indicate that the rock tomb was originally built in the early 18th dynasty. Remains of two tomb-temples of the 20th dynasty and the looted burial of the High Priest of Amun Amenhotep have been identified. After the New Kingdom the tomb was reused as a burial place until the 26th dynasty. The skeletal and mummified material of the different tomb areas underwent a detailed anthropological and paleopathological analysis. The human remains were mostly damaged and scattered due to extensive grave robberies. In total, 79 individuals could be partly reconstructed and investigated. The age and sex distribution revealed a male predominance and a high percentage of young children (< 6 years) and adults in the range of 20 to 40 years. The paleopathological analysis showed a high prevalence of stress markers such as cribra orbitalia in the younger individuals, and other pathological conditions such as dental diseases, degenerative diseases and a possible case of ankylosing spondylitis. Additionally, 13 mummies of an intrusive waste pit could be attributed to three different groups belonging to earlier time periods based on their style of mummification and materials used. The study revealed important information on the age and sex distribution and diseases of the individuals buried in tomb K93.12.

  5. Crystallographic structure of the human leukocyte antigen DRA, DRB3*0101: models of a directional alloimmune response and autoimmunity.

    Science.gov (United States)

    Parry, Christian S; Gorski, Jack; Stern, Lawrence J

    2007-08-10

    We describe structural studies of the human leukocyte antigen DR52a, HLA-DRA/DRB3*0101, in complex with an N-terminal human platelet integrin alphaII(B)betaIII glycoprotein peptide which contains a Leu/Pro dimorphism. The 33:Leu dimorphism is the epitope for the T cell directed response in neonatal alloimmune thrombocytopenia and post-transfusion purpura in individuals with the alphaII(B)betaIII 33:Pro allele, and defines the unidirectional alloimmune response. This condition is always associated with DR52a. The crystallographic structure has been refined to 2.25 A. There are two alphabeta heterodimers to the asymmetric unit in space group P4(1)2(1)2. The molecule is characterized by two prominent hydrophobic pockets at either end of the peptide binding cleft and a deep, narrower and highly charged P4 opening underneath the beta 1 chain. Further, the peptide in the second molecule displays a sharp upward turn after pocket P9. The structure reveals the role of pockets and the distinctive basic P4 pocket, shared by DR52a and DR3, in selecting their respective binding peptide repertoire. We observe an interesting switch in a residue from the canonically assigned pocket 6 seen in prior class II structures to pocket 4. This occludes the P6 pocket helping to explain the distinctive "1-4-9" peptide binding motif. A beta57 Asp-->Val substitution abrogates the salt-bridge to alpha76 Arg and along with a hydrophobic beta37 is important in shaping the P9 pocket. DRB3*0101 and DRB1*0301 belong to an ancestral haplotype and are associated with many autoimmune diseases linked to antigen presentation, but whereas DR3 is susceptible to type 1 diabetes DR52a is not. This dichotomy is explored for clues to the disease.

  6. Crystallographic Structure of the Human Leukocyte Antigen DRA, DRB3*0101: Models of a Directional Alloimmune Respone and Autoimmunity

    Energy Technology Data Exchange (ETDEWEB)

    Parry,C.; Gorski, J.; Stern, L.

    2007-01-01

    We describe structural studies of the human leukocyte antigen DR52a, HLA-DRA/DRB3*0101, in complex with an N-terminal human platelet integrin {alpha}II{sub B}{beta}III glycoprotein peptide which contains a Leu/Pro dimorphism. The 33:Leu dimorphism is the epitope for the T cell directed response in neonatal alloimmune thrombocytopenia and post-transfusion purpura in individuals with the {alpha}II{sub B}{beta}III 33:Pro allele, and defines the unidirectional alloimmune response. This condition is always associated with DR52a. The crystallographic structure has been refined to 2.25 {angstrom}. There are two {alpha}{beta} heterodimers to the asymmetric unit in space group P4{sub 1}2{sub 1}2. The molecule is characterized by two prominent hydrophobic pockets at either end of the peptide binding cleft and a deep, narrower and highly charged P4 opening underneath the beta 1 chain. Further, the peptide in the second molecule displays a sharp upward turn after pocket P9. The structure reveals the role of pockets and the distinctive basic P4 pocket, shared by DR52a and DR3, in selecting their respective binding peptide repertoire. We observe an interesting switch in a residue from the canonically assigned pocket 6 seen in prior class II structures to pocket 4. This occludes the P6 pocket helping to explain the distinctive '1-4-9' peptide binding motif. A {beta}57 Asp {yields} Val substitution abrogates the salt-bridge to {alpha}76 Arg and along with a hydrophobic {beta}37 is important in shaping the P9 pocket. DRB3*0101 and DRB1*0301 belong to an ancestral haplotype and are associated with many autoimmune diseases linked to antigen presentation, but whereas DR3 is susceptible to type 1 diabetes DR52a is not. This dichotomy is explored for clues to the disease.

  7. Toughened and machinable glass matrix composites reinforced with graphene and graphene-oxide nano platelets

    Directory of Open Access Journals (Sweden)

    Harshit Porwal, Peter Tatarko, Salvatore Grasso, Chunfeng Hu, Aldo R Boccaccini, Ivo Dlouhý and Mike J Reece

    2013-01-01

    Full Text Available The processing conditions for preparing well dispersed silica–graphene nanoplatelets and silica–graphene oxide nanoplatelets (GONP composites were optimized using powder and colloidal processing routes. Fully dense silica–GONP composites with up to 2.5 vol% loading were consolidated using spark plasma sintering. The GONP aligned perpendicularly to the applied pressure during sintering. The fracture toughness of the composites increased linearly with increasing concentration of GONP and reached a value of ~0.9 MPa m1/2 for 2.5 vol% loading. Various toughening mechanisms including GONP necking, GONP pull-out, crack bridging, crack deflection and crack branching were observed. GONP decreased the hardness and brittleness index (BI of the composites by ~30 and ~50% respectively. The decrease in BI makes silica–GONP composites machinable compared to pure silica. When compared to silica–Carbon nanotube composites, silica–GONP composites show better process-ability and enhanced mechanical properties.

  8. Mechanical and Thermal Properties of Muscovite and Density Polyethylene-reinforced and-toughened Polypropylene Composites

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lingyan; WEI Tingting; CHEN Huijie; LAI Weiqiang; BU Junfen

    2009-01-01

    The mechanical and thermal properties of polypropylene(PP)/muscovite/ low-density polyethylene(LDPE)/polypropylenegraftmaleic anhydride(PP-g-MAH)ternary com-posites were investigated.In PP matrix,muscovite,LDPE,and PP-g-MAH were added as strength-ening agent,toughening agent,and compatibilizer,respectively.The effects of dosages of the added materials were analyzed.The experimental results show that the optimum recipe of PP/muscovite/LDPE/PP-g-MAH composites is 100/10/6/20(mass ratio).Compared with the pure PP, the mechanical properties of PP/muscovite/LDPE/PP-g-MAH composites,including notched impact strength,Rockwell hardness and flexural strength,are improved.Although tensile strength is slightly decreased,they have better toughness.Filled with muscovite,the heat-resistance and heat-decompostion of the composites are improved.

  9. Effects of nano-SiO2 on reinforcing and toughening polypropylene

    Institute of Scientific and Technical Information of China (English)

    WANG Dong-bo; FENG Yu-jie; TIAN Yan; HAN Li-wei

    2008-01-01

    SiO2 nano particle,through surface modification by silicane coupling agent KH-570,was successfully applied to make nano SiO2/PP composite material by the melt-out blending process with twin-screw extruder.Effects of nano SiO2 on the reinforcing and toughening of PP were studied by analyzing the material impact broken fracture,the crystal structure and the diameter of SiO2 nano particle using SEM,XRD and TEM,respectively.Results showed that the impact strength and the tensile strength of nano SiO2/PP composite material were improved apparently;the impact strength of PP was fracture was increased to 67%when the nano SiO2 content was4%;while the nano SiO2 particle upon surfsce treatment will impose obvious heterogeneous nucleation function over PP crystal.

  10. Research on toughening mechanisms of alumina matrix ceramic composite materials improved by rare earth additive

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xihua; LIU Changxia; LI Musen; ZHANG Jianhua

    2008-01-01

    Mixed rare earth elements were incorporated into alumina ceramic materials. Hot-pressing was used to fabricate alumina matrix composites in nitrogen atmosphere protection. Microstructures and mechanical properties of the composites were tested. It was indicated that the bending strength and fracture toughness of alumina matrix ceramic composites sintered at 1550℃ and 28 Mpa for 30 min were improved evidently. Besides mixed rare earth elements acting as a toughening phase, AlTiC master alloys were also added in as sintering assistants, which could prompt the formation of transient liquid phase, and thus nitrides of rare earth elements were produced. All of the above were beneficial for improving the mechanical properties of alumina matrix ceramic composites.

  11. Factors influencing the Mode I interlaminar fracture toughness of a rubber toughened thermoplastic matrix composite

    Science.gov (United States)

    Parker, D. S.; Yee, A. F.

    1989-01-01

    The use of a rubber modified thermoplastic resin has been investigated as a method to improve the Mode I interlaminar fracture toughness of a unidirectional continuous carbon fiber composite. Test results show that the improvement in the fracture toughness is less than expected due to rubber particle agglomeration, solvent and molding induced crystallization of the matrix and poor fiber/matrix adhesion. The plastic zone in composites utilizing tough matrices can extend well beyond a single interfibrillar spacing. However, the development of the plastic zone is limited due to the failure of the fiber/matrix interface. In order to fully evaluate the potential of tough composites using toughened matrices, any improvement made in the matrix toughness must be coupled with improvements in the fiber/matrix adhesion.

  12. Static and dynamic strain energy release rates in toughened thermosetting composite laminates

    Science.gov (United States)

    Cairns, Douglas S.

    1992-01-01

    In this work, the static and dynamic fracture properties of several thermosetting resin based composite laminates are presented. Two classes of materials are explored. These are homogeneous, thermosetting resins and toughened, multi-phase, thermosetting resin systems. Multi-phase resin materials have shown enhancement over homogenous materials with respect to damage resistance. The development of new dynamic tests are presented for composite laminates based on Width Tapered Double Cantilevered Beam (WTDCB) for Mode 1 fracture and the End Notched Flexure (ENF) specimen. The WTDCB sample was loaded via a low inertia, pneumatic cylinder to produce rapid cross-head displacements. A high rate, piezo-electric load cell and an accelerometer were mounted on the specimen. A digital oscilloscope was used for data acquisition. Typical static and dynamic load versus displacement plots are presented. The ENF specimen was impacted in three point bending with an instrumented impact tower. Fracture initiation and propagation energies under static and dynamic conditions were determined analytically and experimentally. The test results for Mode 1 fracture are relatively insensitive to strain rate effects for the laminates tested in this study. The test results from Mode 2 fracture indicate that the toughened systems provide superior fracture initiation and higher resistance to propagation under dynamic conditions. While the static fracture properties of the homogeneous systems may be relatively high, the apparent Mode 2 dynamic critical strain energy release rate drops significantly. The results indicate that static Mode 2 fracture testing is inadequate for determining the fracture performance of composite structures subjected to conditions such as low velocity impact. A good correlation between the basic Mode 2 dynamic fracture properties and the performance is a combined material/structural Compression After Impact (CAI) test is found. These results underscore the importance of

  13. Grafting Modification of the Reactive Core-Shell Particles to Enhance the Toughening Ability of Polylactide.

    Science.gov (United States)

    Li, Zhaokun; Song, Shixin; Zhao, Xuanchen; Lv, Xue; Sun, Shulin

    2017-08-16

    In order to overcome the brittleness of polylactide (PLA), reactive core-shell particles (RCS) with polybutadiene as core and methyl methacrylate-co-styrene-co-glycidyl methacrylate as shell were prepared to toughen PLA. Tert-dodecyl mercaptan (TDDM) was used as chain transfer agent to modify the grafting properties (such as grafting degree, shell thickness, internal and external grafting) of the core-shell particles. The introduction of TDDM decreased the grafting degree, shell thickness and the Tg of the core phase. When the content of TDDM was lower than 1.15%, the RCS particles dispersed in the PLA matrix uniformly-otherwise, agglomeration took place. The addition of RCS particles induced a higher cold crystallization temperature and a lower melting temperature of PLA which indicated the decreased crystallization ability of PLA. Dynamic mechanical analysis (DMA) results proved the good miscibility between PLA and the RCS particles and the increase of TDDM in RCS induced higher storage modulus of PLA/RCS blends. Suitable TDDM addition improved the toughening ability of RCS particles for PLA. In the present research, PLA/RCS-T4 (RCS-T4: the reactive core-shell particles with 0.76 wt % TDDM addition) blends displayed much better impact strength than other blends due to the easier cavitation/debonding ability and good dispersion morphology of the RCS-T4 particles. When the RCS-T4 content was 25 wt %, the impact strength of PLA/RCS-T4 blend reached 768 J/m, which was more than 25 times that of the pure PLA.

  14. Calcium silicate ceramic scaffolds toughened with hydroxyapatite whiskers for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Pei [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Wei, Pingpin [Cancer Research Institute, Central South University, Changsha 410078 (China); Li, Pengjian; Gao, Chengde [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Shuai, Cijun, E-mail: shuai@csu.edu.cn [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425 (United States); Peng, Shuping, E-mail: shuping@csu.edu.cn [Cancer Research Institute, Central South University, Changsha 410078 (China)

    2014-11-15

    Calcium silicate possessed excellent biocompatibility, bioactivity and degradability, while the high brittleness limited its application in load-bearing sites. Hydroxyapatite whiskers ranging from 0 to 30 wt.% were incorporated into the calcium silicate matrix to improve the strength and fracture resistance. Porous scaffolds were fabricated by selective laser sintering. The effects of hydroxyapatite whiskers on the mechanical properties and toughening mechanisms were investigated. The results showed that the scaffolds had a uniform and continuous inner network with the pore size ranging between 0.5 mm and 0.8 mm. The mechanical properties were enhanced with increasing hydroxyapatite whiskers, reached a maximum at 20 wt.% (compressive strength: 27.28 MPa, compressive Young's modulus: 156.2 MPa, flexural strength: 15.64 MPa and fracture toughness: 1.43 MPa·m{sup 1/2}) and then decreased by addition of more hydroxyapatite whiskers. The improvement of mechanical properties was due to whisker pull-out, crack deflection and crack bridging. Moreover, the degradation rate decreased with the increase of hydroxyapatite whisker content. A layer of bone-like apatite was formed on the scaffold surfaces after being soaked in simulated body fluid. Human osteoblast-like MG-63 cells spread well on the scaffolds and proliferated with increasing culture time. These findings suggested that the calcium silicate scaffolds reinforced with hydroxyapatite whiskers showed great potential for bone regeneration and tissue engineering applications. - Highlights: • HA whiskers were incorporated into CS to improve the properties. • The scaffolds were successfully fabricated by SLS. • Toughening mechanisms was whisker pull-out, crack deflection and bridging. • The scaffolds showed excellent apatite forming ability.

  15. Drug-Induced Liver Injury Associated With Antidepressive Psychopharmacotherapy: An Explorative Assessment Based on Quantitative Signal Detection Using Different MedDRA Terms.

    Science.gov (United States)

    Gahr, Maximilian; Zeiss, René; Lang, Dirk; Connemann, Bernhard J; Hiemke, Christoph; Schönfeldt-Lecuona, Carlos

    2016-06-01

    Drug-induced liver injury is a major problem of pharmacotherapy and is also frequent with antidepressive psychopharmacotherapy. However, there are only few studies using a consistent methodologic approach to study hepatotoxicity of a larger group of antidepress ants. We performed a quantitative signal detection analysis using data from the Uppsala Monitoring Centre from the WHO that records adverse drug reaction (ADR) data from worldwide sources; we retrieved substance- and country-specific (Australia, France, Germany, Italy, Spain, the United Kingdom, and the United States) ADR data and calculated reporting odds ratios as measures for disproportionality within a case/noncase approach. To allow for identification of agents that cause severe forms of hepatotoxic ADRs, we used 2 terms of the MedDRA ("drug-related hepatic disorders-comprehensive search" [DRHD-CS] and "… -severe events only" [DRHD-SEO]). Distribution of signals was heterogeneous throughout the different data sets, and consistent findings were present for only a few substances: agomelatine (AGM) and tianeptine as well as both positive control agents (amineptine, nefazodone) generated signals related to DRHD-CS and DRHD-SEO in all analyzed data sets. Tri- and tetracyclic antidepressants (here amitriptyline, clomipramine, mianserin, mirtazapine, trimipramine) were associated with hepatotoxicity in several data sets. Using 2 MedDRA terms did not allow for detection of agents that cause severe hepatotoxic ADR. Our results support the findings of previous, primarily literature-based, systematic analyses of hepatotoxicity related to antidepressive psychopharmacotherapy. No new safety information could be generated. Application of 2 MedDRA terms did not increase the substance-specific safety information.

  16. The influence of extrinsic motivation on competition-based selection.

    Science.gov (United States)

    Sänger, Jessica; Wascher, Edmund

    2011-10-10

    The biased competition approach to visuo-spatial attention proposes that the selection of competing information is effected by the saliency of the stimulus as well as by an intention-based bias of attention towards behavioural goals. Wascher and Beste (2010) [32] showed that the detection of relevant information depends on its relative saliency compared to irrelevant conflicting stimuli. Furthermore the N1pc, N2pc and N2 of the EEG varied with the strength of the conflict. However, this system could also be modulated by rather global mechanisms like attentional effort. The present study investigates such modulations by testing the influence of extrinsic motivation on the selection of competing stimuli. Participants had to detect a luminance change in various conditions among others against an irrelevant orientation change. Half of the participants were motivated to maximize their performance by the announcement of a monetary reward for correct responses. Participants who were motivated had lower error rates than participants who were not motivated. The event-related lateralizations of the EEG showed no motivation-related effect on the N1pc, which reflects the initial saliency driven orientation of attention towards the more salient stimulus. The subsequent N2pc was enhanced in the motivation condition. Extrinsic motivation was also accompanied by enhanced fronto-central negativities. Thus, the data provide evidence that the improvement of selection performance when participants were extrinsically motivated by announcing a reward was not due to changes in the initial saliency based processing of information but was foremost mediated by improved higher-level mechanisms.

  17. D-alanine modification of a protease-susceptible outer membrane component by the Bordetella pertussis dra locus promotes resistance to antimicrobial peptides and polymorphonuclear leukocyte-mediated killing.

    Science.gov (United States)

    Taneja, Neetu Kumra; Ganguly, Tridib; Bakaletz, Lauren O; Nelson, Kimberly J; Dubey, Purnima; Poole, Leslie B; Deora, Rajendar

    2013-11-01

    Bordetella pertussis is the causative agent of pertussis, a highly contagious disease of the human respiratory tract. Despite very high vaccine coverage, pertussis has reemerged as a serious threat in the United States and many developing countries. Thus, it is important to pursue research to discover unknown pathogenic mechanisms of B. pertussis. We have investigated a previously uncharacterized locus in B. pertussis, the dra locus, which is homologous to the dlt operons of Gram-positive bacteria. The absence of the dra locus resulted in increased sensitivity to the killing action of antimicrobial peptides (AMPs) and human phagocytes. Compared to the wild-type cells, the mutant cells bound higher levels of cationic proteins and peptides, suggesting that dra contributes to AMP resistance by decreasing the electronegativity of the cell surface. The presence of dra led to the incorporation of d-alanine into an outer membrane component that is susceptible to proteinase K cleavage. We conclude that dra encodes a virulence-associated determinant and contributes to the immune resistance of B. pertussis. With these findings, we have identified a new mechanism of surface modification in B. pertussis which may also be relevant in other Gram-negative pathogens.

  18. Automated segmentation of cerebral vasculature with aneurysms in 3DRA and TOF-MRA using geodesic active regions: An evaluation study

    Energy Technology Data Exchange (ETDEWEB)

    Bogunovic, Hrvoje; Pozo, Jose Maria; Villa-Uriol, Maria Cruz [Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Universitat Pompeu Fabra (UPF) and Networking Biomedical Research Center on Bioengineering, Biomaterials and Nanomedicine - CIBER-BBN, Barcelona 08018 (Spain); and others

    2011-01-15

    Purpose: To evaluate the suitability of an improved version of an automatic segmentation method based on geodesic active regions (GAR) for segmenting cerebral vasculature with aneurysms from 3D x-ray reconstruction angiography (3DRA) and time of flight magnetic resonance angiography (TOF-MRA) images available in the clinical routine. Methods: Three aspects of the GAR method have been improved: execution time, robustness to variability in imaging protocols, and robustness to variability in image spatial resolutions. The improved GAR was retrospectively evaluated on images from patients containing intracranial aneurysms in the area of the Circle of Willis and imaged with two modalities: 3DRA and TOF-MRA. Images were obtained from two clinical centers, each using different imaging equipment. Evaluation included qualitative and quantitative analyses of the segmentation results on 20 images from 10 patients. The gold standard was built from 660 cross-sections (33 per image) of vessels and aneurysms, manually measured by interventional neuroradiologists. GAR has also been compared to an interactive segmentation method: isointensity surface extraction (ISE). In addition, since patients had been imaged with the two modalities, we performed an intermodality agreement analysis with respect to both the manual measurements and each of the two segmentation methods. Results: Both GAR and ISE differed from the gold standard within acceptable limits compared to the imaging resolution. GAR (ISE) had an average accuracy of 0.20 (0.24) mm for 3DRA and 0.27 (0.30) mm for TOF-MRA, and had a repeatability of 0.05 (0.20) mm. Compared to ISE, GAR had a lower qualitative error in the vessel region and a lower quantitative error in the aneurysm region. The repeatability of GAR was superior to manual measurements and ISE. The intermodality agreement was similar between GAR and the manual measurements. Conclusions: The improved GAR method outperformed ISE qualitatively as well as

  19. Extrinsic allergic alveolitis: a disease commoner in non-smokers.

    Science.gov (United States)

    Warren, C P

    1977-01-01

    The smoking habits of 18 patients with extrinsic allergic alveolitis, 22 with cryptogenic fibrosing alveolitis, and 75 patients with sarcoidosis were compared with the smoking habits of the normal population of the Prairie Region for 1973. The patients were diagnosed at the same two hospitals over the four-year period November 1971--75 and were of comparable age. Non-smoking was significantly associated with allergic alveolitis in men and the three cases in women were all non-smokers. For the other two diseases, smoking habits were similar to those of the local population. PMID:594937

  20. [Extrinsic allergic alveolitis: a review for the practitioner].

    Science.gov (United States)

    Pralong, G; Leuenberger, P

    1998-08-22

    Extrinsic allergic alveolitis (EAA) or hypersensitivity pneumonitis (HP) is a clinical syndrome characterised by an inflammatory, partly granulomatous, immune disorder involving interstitial and alveolar spaces secondary to inhalation of organic substances. The disorder is mainly due to occupational exposure, farmer's lung being the best-known example. Acute, subacute or chronic forms can be clinically differentiated. Given the fact that chronic forms may present a pattern of irreversible pulmonary fibrosis, clinicians must be aware of the diagnosis of EAA in every situation where the history shows a potential antigenic exposure. Prevention should be reinforced by increasing individual protective measures and by improving techniques used at the workplace.

  1. Extrinsic sound stimulations and development of periphery auditory synapses

    Institute of Scientific and Technical Information of China (English)

    Kun Hou; Shiming Yang; Ke Liu

    2015-01-01

    The development of auditory synapses is a key process for the maturation of hearing function. However, it is still on debate regarding whether the development of auditory synapses is dominated by acquired sound stimulations. In this review, we summarize relevant publications in recent decades to address this issue. Most reported data suggest that extrinsic sound stimulations do affect, but not govern the development of periphery auditory synapses. Overall, periphery auditory synapses develop and mature according to its intrinsic mechanism to build up the synaptic connections between sensory neurons and/or interneurons.

  2. Spectral dependences of extrinsic optical absorption in sillenite crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kisteneva, M G; Khudyakova, E S; Shandarov, S M; Akrestina, A S; Dyu, V G [Tomsk State University of Control Systems and Radioelectronics, Tomsk (Russian Federation); Kargin, Yu F [A.A.Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-07-31

    The influence of laser irradiation at wavelengths of 532 and 655 nm and annealing in air at temperatures from 200 to 370 °C on optical absorption spectra of undoped bismuth silicon oxide and bismuth germanium oxide and aluminium-doped bismuth titanium oxide crystals has been studied experimentally. The experimental data have been interpreted in terms of a model for extrinsic absorption that takes into account not only the contribution of the photoexcitation of electrons from deep donor centres with a normal distribution of their concentration with respect to ionisation energy but also that of intracentre transitions. (laser applications and other topics in quantum electronics)

  3. Older adults' intrinsic and extrinsic motivation toward physical activity.

    Science.gov (United States)

    Dacey, Marie; Baltzell, Amy; Zaichkowsky, Len

    2008-01-01

    To examine how motives discriminate 3 physical activity levels of inactive, active, and sustained maintainers. Six hundred forty-five adults (M age = 63.8) completed stage-of-change and Exercise Motivations Inventory (EMI-2) scales. Exploratory factor analysis established psychometric properties of the EMI-2 suitable for older adults. Six factors emerged in the EMI-2: health and fitness, social/emotional benefits, weight management, stress management, enjoyment, and appearance. Enjoyment contributed most to differentiating activity levels. Moderators of age and gender were delineated. Intrinsic motivation and self-determined extrinsic motivation distinguish older adults' activity levels.

  4. Mechanical Properties and Erosive Wear Resistance of Zirconia Toughened Al2O3-TiC Ceramics

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The effect of ZrO2 content on the fracture toughness, flexural strength and Vickers hardness as well as the erosive wear resistant properties of zirconia toughened Al2O3-TiC ceramic composites has been investigated. The results showed that the improvement in fracture toughness and flexure strength of composites with the content of zirconia less than 50% and 10% in mass fraction respectively, is primarily attributed to stress-induced transformation toughening by the analyse of X-ray diffraction. The dependance of erosion wear resistance on the attack angle and the content of ZrO2 particles of the composites was also revealed. It is found that the erosion rate of the composites has a sharp rise at a attack angle over 65€?. This phenomenon is due to a brittle response to the erosion test by microstructural observation on eroded surface.

  5. Integrated ternary artificial nacre via synergistic toughening of reduced graphene oxide/double-walled carbon nanotubes/poly(vinyl alcohol)

    Science.gov (United States)

    Gong, Shanshan; Wu, Mengxi; Jiang, Lei; Cheng, Qunfeng

    2016-07-01

    The synergistic toughening effect of building blocks and interface interaction exists in natural materials, such as nacre. Herein, inspired by one-dimensional (1D) nanofibrillar chitin and two-dimensional (2D) calcium carbonate platelets of natural nacre, we have fabricated integrated strong and tough ternary bio-inspired nanocomposites (artificial nacre) successfully via the synergistic effect of 2D reduced graphene oxide (rGO) nanosheets and 1D double-walled carbon nanotubes (DWNTs) and hydrogen bonding cross-linking with polyvinyl alcohol (PVA) matrix. Moreover, the crack mechanics model with crack deflection by 2D rGO nanosheets and crack bridging by 1D DWNTs and PVA chains induces resultant artificial nacre exhibiting excellent fatigue-resistance performance. These outstanding characteristics enable the ternary bioinspired nanocomposites have many promising potential applications, for instance, aerospace, flexible electronics devices and so forth. This synergistic toughening strategy also provides an effective way to assemble robust graphene-based nanocomposites.

  6. Transformation toughening of Al2O3/ZrO2 laminated ceramics with residual compressive stress

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With the help of scanning electronic microscopy and X-ray diffraction, the relationships of microstmcture characteristics,phase assemblage, and fracture micrograph of Al2O3/ZrO2 laminated ceramics were studied. Compared with monolithic Al2O3/ZrO2 ceramics, the existence of surface compressive stresses greatly restrained the growth of ZrO2 and Al2O3 grains at high sinter temperature, fined the grain size, and increased the content of metastable t-ZrO2, which made the fracture transformation energy quantity 70% higher than that of the monolithic ceramics. The trans-granular and inter-granular fracture features were observed in the surface and center layers, which further verified that transformation toughening is the main mechanism, whereas, micro-crack toughening is helpful for enhancing fracture toughness.

  7. TURBO DECODER USING LOCAL SUBSIDIARY MAXIMUM LIKELIHOOD DECODING IN PRIOR ESTIMATION OF THE EXTRINSIC INFORMATION

    Institute of Scientific and Technical Information of China (English)

    Yang Fengfan

    2004-01-01

    A new technique for turbo decoder is proposed by using a local subsidiary maximum likelihood decoding and a probability distributions family for the extrinsic information. The optimal distribution of the extrinsic information is dynamically specified for each component decoder.The simulation results show that the iterative decoder with the new technique outperforms that of the decoder with the traditional Gaussian approach for the extrinsic information under the same conditions.

  8. CTBN-TOUGHENED EPOXY RESINS——EFFECT OF CURING MECHANISM ON NETWORK STRUCTURE OF THE RUBBER PHASE

    Institute of Scientific and Technical Information of China (English)

    SONG Aiteng; YU Yunzhao

    1990-01-01

    Epoxy resins toughened with carboxyl-terminated butadieneacrylonitrile copolymers ( CTBN ) are two-phase thermosets. The network of the in situ formed rubber particles depends upon the curing mechanism of the resin. When a primary polyamine such as triethylene tetramine was used as curing agent, the network of the rubber phase was quite incomplete, whereas a perfect rubber network was formed with 2-ethyl-4-methyl imidazole as the curing agent.

  9. EFFECT OF THERMOMECHANICAL TREATMENT ON TOUGHENING OF Al-Li-Cu-Mg-Zr ALLOY AND ITS TOUGHNESS

    OpenAIRE

    Niinomi, M; Degawa, K.; Kobayashi, T.(International Center for Elementary Particle Physics and Department of Physics, The University of Tokyo, Tokyo, Japan)

    1987-01-01

    The effect of the thermomechanical treatment for toughening the Al-Li-Cu-Mg-Zr alloy was investigated using the computer aided instrumented Charpy impact testing (CAI) system. In addition, the temperature dependence of the toughness of this alloy was also investigated. The intermediate thermomechanical treatment originally developed by Rockwell International Co. (RI-ITMT) was proved to be effective in increasing the toughness of this alloy. The toughness of this alloy increased with the decre...

  10. RECENT PROGRESS IN THE FABRICATION AND CHARACTERIZATION OF DUCTILE-PHASE-TOUGHENED TUNGSTEN LAMINATES FOR PLASMA-FACING MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, Kevin; Odette, G Robert; Fields, Kirk A.; Gragg, David; Yamamoto, Takuya; Zok, Frank W.; Henager, Charles H.; Kurtz, Richard J.; Roosendaal, Timothy J.; Borlaug, Brennan A.

    2015-09-23

    A promising approach to increasing the fracture toughness of W-alloys is ductile-phase toughening (DPT). A ductile phase reinforcement in a brittle matrix increases toughness primarily by crack bridging. A W-Cu laminate was fabricated and the properties of the constituent metals were characterized along with those for the composite. Development of a design model for large-scale crack bridging continued.

  11. Coordination of intrinsic and extrinsic foot muscles during walking.

    Science.gov (United States)

    Zelik, Karl E; La Scaleia, Valentina; Ivanenko, Yuri P; Lacquaniti, Francesco

    2015-04-01

    The human foot undergoes complex deformations during walking due to passive tissues and active muscles. However, based on prior recordings it is unclear if muscles that contribute to flexion/extension of the metatarsophalangeal (MTP) joints are activated synchronously to modulate joint impedance, or sequentially to perform distinct biomechanical functions. We investigated the coordination of MTP flexors and extensors with respect to each other, and to other ankle-foot muscles. We analyzed surface electromyographic (EMG) recordings of intrinsic and extrinsic foot muscles for healthy individuals during level treadmill walking, and also during sideways and tiptoe gaits. We computed stride-averaged EMG envelopes and used the timing of peak muscle activity to assess synchronous vs. sequential coordination. We found that peak MTP flexor activity occurred significantly before peak MTP extensor activity during walking (P walking tended to dissociate during other locomotor tasks. For instance, extensor hallucis brevis and extensor digitorum brevis muscle activation peaks decoupled during sideways gait. The sequential peak activity of MTP flexors followed by MTP extensors suggests that their biomechanical contributions may be largely separable from each other and from other extrinsic foot muscles during walking. Meanwhile, the task-specific coordination of the foot muscles during other modes of locomotion indicates a high-level of specificity in their function and control.

  12. Intrinsic and Extrinsic Science: A Dialectic of Scientific Fame.

    Science.gov (United States)

    Feist, Gregory J

    2016-11-01

    In this article, I argue that scientific fame and impact exists on a continuum from the mundane to the transformative/revolutionary. Ideally, one achieves fame and impact in science by synthesizing two extreme career prototypes: intrinsic and extrinsic research. The former is guided by interest, curiosity, passion, gut, and intuition for important untapped topics. The latter is guided by money, grants, and/or what is being published in top-tier journals. Assessment of fame and impact in science ultimately rests on productivity (publication) and some variation of its impact (citations). In addition to those traditional measures of impact, there are some relatively new metrics (e.g., the h index and altmetrics). If psychology is to achieve consensual cumulative progress and better rates of replication, I propose that upcoming psychologists would do well to understand that success is not equal to fame and that individual career success is not necessarily the same as disciplinary success. Finally, if one is to have a successful and perhaps even famous career in psychological science, a good strategy would be to synthesize intrinsic and extrinsic motives for one's research.

  13. The effect of extrinsic attributes on liking of cottage cheese.

    Science.gov (United States)

    Hubbard, E M; Jervis, S M; Drake, M A

    2016-01-01

    Preference mapping studies with cottage cheese have demonstrated that cottage cheese liking is influenced by flavor, texture, curd size, and dressing content. However, extrinsic factors such as package, label claims, and brand name may also influence liking and have not been studied. The objective of this study was to evaluate the role of package attributes and brand on the liking of cottage cheese. A conjoint survey with Kano analysis (n=460) was conducted to explore the effect of extrinsic attributes (brand, label claim, milkfat content, and price) on liking. Following the survey, 150 consumers evaluated intrinsic attributes of 7 cottage cheeses with and without brand information in a 2-d crossover design. Results were evaluated by 2-way ANOVA and multivariate analyses. Milkfat content and price had the highest influence on liking by conjoint analysis. Cottage cheese with 2% milkfat and a low price was preferred. Specific label claims such as "excellent source of calcium (>10%)" were more attractive to consumers than "low sodium" or "extra creamy." Branding influenced overall liking and purchase intent for cottage cheeses to differing degrees. For national brands, acceptance scores were enhanced in the presence of the brand. An all-natural claim was more appealing than organic by conjoint analysis and this result was also confirmed with consumer acceptance testing. Findings from this study can help manufacturers, as well as food marketers, better target their products and brands with attributes that drive consumer choice.

  14. Extrinsic labelling of zinc and calcium in bread

    Energy Technology Data Exchange (ETDEWEB)

    Fredlund, Kerstin E-mail: mlw@fsc.chalmers.se; Rossander-Hulthen, Lena; Isaksson, Mats; Almgren, Annette; Sandberg, A.-S

    2002-08-01

    This study investigated the effect of different means of extrinsic administration of {sup 65}Zn and {sup 47}Ca in white wheat flour bread on the measured absorption. Eight healthy subjects were served 80 g of labelled bread as a standardized breakfast after an overnight fast on three occasions. Extrinsic labelling of the meals with {sup 65}Zn and {sup 47}Ca was done in three ways: (a) by adding the isotopes to the bread 16 h before it was served, (b) by adding the isotopes shortly before serving or (c) by adding the isotopes to the water used in dough making. Zinc and calcium chloride corresponding to 3.2 mg (49 {mu}mol) zinc and 275 mg (6.9 mmol) calcium in one portion were added to the dough. Whole-body retention was measured by whole-body counting. The fractional absorption of zinc was (a) 0.243{+-}0.122, (b) 0.217{+-}0.101 and (c) 0.178{+-}0.063 (mean{+-}SD), and the fractional absorption of calcium (expressed as calcium retention on day 7) was (a) 0.351{+-}0.108, (b) 0.357{+-}0.131 and (c) 0.334{+-}0.117 (mean{+-}SD). No significant difference (p>0.05) was seen between the different ways for either zinc nor calcium.

  15. In/extrinsic granularity in superconducting boron-doped diamond

    Energy Technology Data Exchange (ETDEWEB)

    Willems, B.L. [INPAC - Institute for Nanoscale Physics and Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B - 3001 Leuven (Belgium); Facultad de Ciencias Fisicas, Universidad Nacional Mayor de San Marcos, P.O. 14-0149, Lima-14 (Peru); Zhang, G. [INPAC - Institute for Nanoscale Physics and Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B - 3001 Leuven (Belgium); Vanacken, J., E-mail: johan.vanacken@fys.kuleuven.b [INPAC - Institute for Nanoscale Physics and Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B - 3001 Leuven (Belgium); Moshchalkov, V.V. [INPAC - Institute for Nanoscale Physics and Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B - 3001 Leuven (Belgium); Guillamon, I.; Suderow, H.; Vieira, S. [Laboratorio de Bajas Temperaturas, Departamento de Fisica de la Materia Condensada, Universidad Autonoma de Madrid (Spain); Janssens, S.D. [Hasselt University, Institute for Materials Research, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Haenen, K.; Wagner, P. [Hasselt University, Institute for Materials Research, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Division IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek (Belgium)

    2010-10-01

    When charge carriers are introduced in diamond, e.g. by chemical doping with Boron (B), the C{sub 1-x}B{sub x} diamond:B can exhibit an insulator-to-metal transition (p{sub Mott{approx}}2x10{sup 20}cm{sup -3}). Under even heavier boron doping (n{sub B{approx}}10{sup 21}cm{sup -3}), diamond becomes superconducting. Using microwave plasma-assisted chemical vapor deposition (MPCVD) we have prepared diamond:B thin films with critical offset temperatures T{sub C} below 3 K. We have investigated the transport properties of these diamond:B thin films, which show pronounced granular effects. It turns out, that this granularity is both intrinsic as well as extrinsic. The extrinsic granularity is the effect of the growth method which needs to start from a seeding of the substrate with detonation nanodiamond, which acts as nucleation centers for further MPCVD growth of the film. In using SPM/STM techniques, we also observed intrinsic granularity, meaning that within physical grains, we observe also a strong intragrain modulation of the order parameter. As a consequence of these granularities, the transport properties show evidence of (i) strong superconducting fluctuations and (ii) Cooper pair tunneling and/or quasiparticle tunneling. The latter effects explain the observed negative magnetoresistance.

  16. Intrinsic and extrinsic influences on children's acceptance of new foods.

    Science.gov (United States)

    Blissett, Jackie; Fogel, Anna

    2013-09-10

    The foods that tend to be rejected by children include those which may have greatest importance for later health. This paper reviews some of the intrinsic and extrinsic influences on preschool children's eating behavior, with particular reference to their acceptance of new foods into their diet. Factors conceptualized as intrinsic to the child in this review include sensory processing, taste perception, neophobia, and temperament. The important extrinsic determinants of children's food acceptance which are reviewed include parental and peer modeling, the family food environment, infant feeding practices including breastfeeding and age at weaning, concurrent feeding practices including restriction, pressure to eat, prompting and reward, and the taste & energy content of foods. Children's willingness to accept new foods is influenced by a wide range of factors that likely have individual and also interactive effects on children's willingness to taste, and then continue to eat, new foods. The literature lacks longitudinal and experimental studies, which will be particularly important in determining interventions most likely to be effective in facilitating children's acceptance of healthy foods.

  17. Voloshina I.B., Metlov V.G., Shugarov S.Yu., Golovin A.V., Antoniuk O.I. Positive and Negative Superhumps of the Dwarf Nova MN Dra

    Science.gov (United States)

    Samsonov, D. A.; Pavlenko, E. P.; Andreev, M. V.; Sklyanov, A.; Zubareva, A. M.

    2010-12-01

    We present the result of O-C analysis of the dwarf nova MN Dra. It is based on the multi-site photometric observations that were made over 77 nights in August - November, 2009. The total exposure was 433 hours. During this time binary underwent two superoutbursts and five normal outbursts. In superoutbursts the positive superhumps decreased with extremely large P = -(3 - 8) x 10-4 for SU UMa-like dwarf novae, confirming the known behavior of MN Dra in 2003. MN Dra displayed large-amplitude (up to 1.4m in quiescence and 0.1m-0.2m in normal outbursts) negative superhumps. The improved value of negative superhump period is 0.095952(4) d.

  18. Carboxyl-terminated butadiene-acrylonitrile-toughened epoxy/carboxyl-modified carbon nanotube nanocomposites: Thermal and mechanical properties

    Directory of Open Access Journals (Sweden)

    H. F. Xie

    2012-09-01

    Full Text Available Carboxyl-modified multi-walled carbon nanotubes (MWCNT–COOHs as nanofillers were incorporated into diglycidyl ether of bisphenol A (DGEBA toughened with carboxyl-terminated butadiene-acrylonitrile (CTBN. The carboxyl functional carbon nanotubes were characterized by Fourier-transform infrared spectroscopy and thermogravimetric analysis. Furthermore, cure kinetics, glass transition temperature (Tg, mechanical properties, thermal stability and morphology of DGEBA/CTBN/MWCNT–COOHs nanocomposites were investigated by differential scanning calorimetry (DSC, dynamic mechanical analysis (DMA, universal test machine, thermogravimetric analysis and scanning electron microscopy (SEM. DSC kinetic studies showed that the addition of MWCNT–COOHs accelerated the curing reaction of the rubber-toughened epoxy resin. DMA results revealed that Tg of rubber-toughened epoxy nanocomposites lowered with MWCNT–COOH contents. The tensile strength, elongation at break, flexural strength and flexural modulus of DGEBA/CTBN/MWCNT-COOHs nanocomposites were increased at lower MWCNT-COOH concentration. A homogenous dispersion of nanocomposites at lower MWCNT–COOH concentration was observed by SEM.

  19. Nuevos profesores eméritos de San Marcos: Dra. Luz Sarmiento Bendezú y el Dr. Hernando De Macedo Ruiz

    Directory of Open Access Journals (Sweden)

    Julio Manosalva Bacigalupo

    2013-06-01

    Full Text Available El día martes 17 de diciembre del año 2002, en el recinto histórico de la Capilla de la Virgen de Loreto del Centro Cultural de la Universidad Nacional Mayor de San Marcos del Parque Universitario, en presencia del Dr. Manuel Burga Díaz, Rector de nuestra Cuatricentenaria Casa de Estudios, el Vicerrector Académico Dr. Raúl Izaguirre Maguiña, la Vicerrectora Administrativa, Dra. Beatriz Herrera García, decanos, autoridades de nuestra Facultad, profesores, compañeros de promoción, familiares y amigos, se rindió un emotivo homenaje a dos grandes maestros forjadores de Escuelas de Investigación y docencia, que han contribuido positivamente al desarrollo de la zoología en la antigua Facultad de Ciencias y posteriormente en la Facultad de Ciencias Biológicas: la Dra. Luz Sarmiento Bendezú y el Dr. Hernando de Macedo Ruíz.

  20. Toughening mechanisms in melt manipulated thermoplastics (PS and PC) and in novel modified epoxies

    Science.gov (United States)

    Hydro, Ryan Michael

    This study examined the deformation mechanisms associated with the fatigue and fracture of polystyrene (PS) and polycarbonate (PC) processed using a novel polymer melt manipulation technique, vibration-assisted injection molding (VAIM), as well as the toughening mechanisms of several epoxy resins modified with several novel block co-polymers. VAIM processed PS was found to possess a tensile strength 28% greater than conventionally processed PS, which is in agreement with previous research. The increase in tensile strength is due to the higher craze initiation stress required to overcome the thicker "frozen in" layer of the VAIM processed specimens. Also, the residual orientation present in VAIM specimens appears to retard craze propagation and this is evident by shear banding. Unfortunately, VAIM processed PS did not result in a fatigue lifetime improvement. In fatigue, the PS specimens processed either way usually resulted in the initiation and propagation of a single "killer craze" that caused failure. In contrast, the VAIM processed PC did not exhibit a significant improvement in tensile strength compared against the conventionally molded specimens. In cyclic loading, for the two stress levels examined, both the VAIM and conventional PC specimens were found to perform equally---when examining the average lifetimes and their corresponding standard deviations. In addition, this work studied the deformation mechanisms associated with novel block co-polymer modified epoxies. It was found that the plane strain fracture toughness, KIC, was on the order of 3.0MPa√m for the NanoStrength(TM) E20 modified AEP and PIP cured systems, which is comparable to micro-segregated core-shell particles. Toughness improvements significantly depended on cross-link density of the epoxy matrix, curing agent, and on the amount of polybutadiene present in the toughening agents examined. The system with the highest, KIC, was selected to make a conductive adhesive using 30nm diameter Ag

  1. Efficacy test of a toothpaste in reducing extrinsic dental stain

    Science.gov (United States)

    Agustanti, A.; Ramadhani, S. A.; Adiatman, M.; Rahardjo, A.; Callea, M.; Yavuz, I.; Maharani, D. A.

    2017-08-01

    This clinical trial compared the external dental stain reduction achieved by tested toothpaste versus placebo in adult patients. In this double-blind, parallel, randomised clinical trial, 45 female volunteers with a mean age of 20 years old were included. All study subjects front teeth were topically applicated with Silver Diamine Fluoride (SDF) to create external dental stains. Subjects were randomized into test (n=22) and control (n=23) groups. Toothpastes were used for two days to analyse the effects of removing external stains on the labial surfaces of all anterior teeth. VITA Easyshade Advance 4.0 was used to measure dental extrinsic stains changes. The analysis showed statistically significant efficacy of the tested toothpaste in reducing external dental stain caused by SDF, comparing to the placebo toothpaste, after one and two days of usage. The tested toothpaste was effective in reducing dental stain.

  2. Extrinsic factors affecting accuracy of ultrasonic flowmeters for LMFBRs

    Energy Technology Data Exchange (ETDEWEB)

    Managan, W.W.

    1976-08-01

    Assuming that ultrasonic flowmeters of suitable intrinsic accuracy are feasible, this report explores factors extrinsic to the flowmeter which affect the accuracy such as asymmetric flow profile, regions of high turbulence and thermal stratification. By integrating isovelocity flow profile maps, the predicted performance of various flowmeter configurations may be compared to experimental data. For the two pipe arrangements analyzed, the single diametral path flowmeter results were within 5 percent of true flow rate. Theoretical correction factors could reduce the error for the straight pipe but increased the error for asymmetrical flow. On the same pipe arrangements a four path ultrasonic flowmeter spaced for Gaussian integration gave less than 1 percent error. For more general conclusions a range of flow profiles produced by typical LMFBR piping arrangements must be analyzed.

  3. Extrinsic allergic alveolitis induced by the yeast Debaryomyces hansenii.

    Science.gov (United States)

    Yamamoto, Y; Osanai, S; Fujiuchi, S; Yamazaki, K; Nakano, H; Ohsaki, Y; Kikuchi, K

    2002-11-01

    A 65-yr-old female developed cough, fever and dyspnoea following repeated exposure to a home ultrasonic humidifier. High-resolution computed tomography showed ground-glass opacity in both lung fields. Arterial blood gas analysis gave an oxygen tension of 8.38 kPa (63 Torr). Pulmonary function testing revealed restrictive ventilatory impairment with a reduction in the diffusing capacity. The diagnosis of extrinsic allergic alveolitis (EAA) was confirmed by radiographic findings, pathological evidence of alveolitis and reproductive development by a provocation test to the humidifier water. The yeast Debaryomyces Hansenii was the only microorganism cultured from the water of the humidifier. The double diffusion precipitating test and lymphocyte proliferative response was positive for an extract of D. Hansenii, providing evidence to incriminate this fungus. This is the first described case of EAA caused by D. Hansenii.

  4. MATERIAL ELEMENT MODEL FOR EXTRINSIC SEMICONDUCTORS WITH DEFECTS OF DISLOCATION

    Directory of Open Access Journals (Sweden)

    Maria Paola Mazzeo

    2011-07-01

    Full Text Available In a previous paper we outlined a geometric model for the thermodynamic description of extrinsic semiconductors with defects of dislocation.Applying a geometrization technique, within the rationalextended irreversible thermodynamics with internal variables, the dynamical system for simple material elements of these media, the expressions of the entropy function and the entropy 1-form were obtained. In this contribution we deepen the study of this geometric model. We give a detailed description of the defective media under consideration and of the dislocation core tensor, we introduce the transformation induced by the process and, applying the closure conditions for the entropy 1-form, we derive the necessary conditions for the existence of the entropy function. These and other results are new in the paper.The derivation of the relevant entropy 1-form is the starting point to introduce an extended thermodynamical phase space.

  5. Measurement of Spin Pumping Voltage Separated from Extrinsic Microwave Effects

    Science.gov (United States)

    Iguchi, Ryo; Saitoh, Eiji

    2017-01-01

    Conversions between spin and charge currents are core technologies in recent spintronics. In this article, we provide methods for estimating inverse spin Hall effects (ISHEs) induced by using microwave-driven spin pumping (SP) as a spin-current generator. ISHE and SP induce an electromotive force at the ferromagnetic or spin-wave resonance, which offers a valuable electric method of studying spin physics in materials. At the resonance, a microwave for exciting the magnetization dynamics induces an additional electromotive force via rf-current rectification and thermoelectric effects. We discuss methods of separating the signals generated from such extrinsic microwave effects by controlling sample structures and configurations. These methods are helpful in performing accurate measurements on ISHE induced by SP, enabling quantitative studies on the conversion between spin and charge currents on various kinds of materials.

  6. Alberta Consumers' Valuation of Extrinsic and Intrinsic Red Meat Attributes

    DEFF Research Database (Denmark)

    Steiner, Bodo; Gao, Fei; Unterschultz, Jim

    2010-01-01

    This paper analyzes Alberta consumers’ perceptions toward extrinsic and intrinsic attributes of bison and beef steaks. In contrast to published Canadian consumer studies on bison meat that were undertaken prior to May 2003, before the first BSE case of Canadian origin was identified in beef cattle......, this study provides a “post-BSE” assessment of consumer perceptions toward selected bison meat attributes. The results from an attribute-based choice experiment provide little support that simple traceability assurance schemes have value to consumers of bison and beef steaks, thus confirming similar findings...... of earlier beef studies that have employed different methodological approaches. The results also suggest that consumers are willing to pay significant premiums for bison steaks that are certified as being produced without genetically modified organisms, an attribute that has so far been unexplored...

  7. Extrinsic and intrinsic motivation at 30: Unresolved scientific issues.

    Science.gov (United States)

    Reiss, Steven

    2005-01-01

    The undermining effect of extrinsic reward on intrinsic motivation remains unproven. The key unresolved issues are construct invalidity (all four definitions are unproved and two are illogical); measurement unreliability (the free-choice measure requires unreliable, subjective judgments to infer intrinsic motivation); inadequate experimental controls (negative affect and novelty, not cognitive evaluation, may explain "undermining" effects); and biased metareviews (studies with possible floor effects excluded, but those with possible ceiling effects included). Perhaps the greatest error with the undermining theory, however, is that it does not adequately recognize the multifaceted nature of intrinsic motivation (Reiss, 2004a). Advice to limit the use of applied behavior analysis based on "hidden" undermining effects is ideologically inspired and is unsupported by credible scientific evidence.

  8. The Technologies of Normalization and Self: Thinking about IRBs and Extrinsic Research Ethics with Foucault

    Science.gov (United States)

    Koro-Ljungberg, Mirka; Gemignani, Marco; Brodeur, Cheri Winton; Kmiec, Cheryl

    2007-01-01

    In this article, the authors discuss the technologies of normalization and self in relation to ethics and the problematization of extrinsic research ethics. They argue that institutional review boards (IRBs) and other similar institutional mechanisms promote extrinsic forms of ethics that are exemplified through institutionalized structures such…

  9. Intrinsic and Extrinsic School Motivation as a Function of Age: The Mediating Role of Autonomy Support

    Science.gov (United States)

    Gillet, Nicolas; Vallerand, Robert J.; Lafreniere, Marc-Andre K.

    2012-01-01

    The main purpose of the present research was to investigate school intrinsic and extrinsic motivation, and amotivation as a function of age in a sample of 1,600 elementary and high school students aged 9-17 years. First, results revealed a systematic decrease in intrinsic motivation and self-determined extrinsic motivation from age 9 to 12 years,…

  10. Creating Rich Portraits: A Mixed-Methods Approach to Understanding Profiles of Intrinsic and Extrinsic Motivations

    Science.gov (United States)

    Corpus, Jennifer Henderlong; Wormington, Stephanie V.; Haimovitz, Kyla

    2016-01-01

    A person-centered, mixed-methods approach (self-report surveys, semistructured interviews, school records) was used to characterize and evaluate profiles of intrinsic and extrinsic motivations among 243 third- through eighth-grade students. Cluster analysis suggested four distinct profiles: high quantity (high intrinsic, high extrinsic), primarily…

  11. Intrinsic and Extrinsic School Motivation as a Function of Age: The Mediating Role of Autonomy Support

    Science.gov (United States)

    Gillet, Nicolas; Vallerand, Robert J.; Lafreniere, Marc-Andre K.

    2012-01-01

    The main purpose of the present research was to investigate school intrinsic and extrinsic motivation, and amotivation as a function of age in a sample of 1,600 elementary and high school students aged 9-17 years. First, results revealed a systematic decrease in intrinsic motivation and self-determined extrinsic motivation from age 9 to 12 years,…

  12. Intrinsic and Extrinsic Origins of the Polar Kerr Effect in a Chiral p-WAVE Superconductor

    Science.gov (United States)

    Goryo, Jun

    Recently, the measurement of the polar Kerr effect (PKE) in the quasi two-dimensional superconductor Sr2RuO4, which is motivated to observe the chirality of px + ipy-wave pairing, has been reported. We clarify that the PKE has intrinsic and extrinsic (disorder-induced) origins. The extrinsic contribution would be dominant in the PKE experiment.

  13. Do people differentiate between intrinsic and extrinsic goals for physical activity?

    Science.gov (United States)

    McLachlan, Sarah; Hagger, Martin S

    2011-04-01

    The distinction between intrinsic and extrinsic goals, and between goal pursuit for intrinsically and extrinsically motivated reasons, is a central premise of self-determination theory. Proponents of the theory have proposed that the pursuit of intrinsic goals and intrinsically motivated goal striving each predict adaptive psychological and behavioral outcomes relative to the pursuit of extrinsic goals and extrinsically motivated goal striving. Despite evidence to support these predictions, research has not explored whether individuals naturally differentiate between intrinsic and extrinsic goals. Two studies tested whether people make this differentiation when recalling goals for leisure-time physical activity. Using memory-recall methods, participants in Study 1 were asked to freely generate physical activity goals. A subsample (N = 43) was asked to code their freely generated goals as intrinsic or extrinsic. In Study 2, participants were asked to recall intrinsic and extrinsic goals after making a decision regarding their future physical activity. Results of these studies revealed that individuals' goal generation and recall exhibited significant clustering by goal type. Participants encountered some difficulties when explicitly coding goals. Findings support self-determination theory and indicate that individuals discriminate between intrinsic and extrinsic goals.

  14. Creating Rich Portraits: A Mixed-Methods Approach to Understanding Profiles of Intrinsic and Extrinsic Motivations

    Science.gov (United States)

    Corpus, Jennifer Henderlong; Wormington, Stephanie V.; Haimovitz, Kyla

    2016-01-01

    A person-centered, mixed-methods approach (self-report surveys, semistructured interviews, school records) was used to characterize and evaluate profiles of intrinsic and extrinsic motivations among 243 third- through eighth-grade students. Cluster analysis suggested four distinct profiles: high quantity (high intrinsic, high extrinsic), primarily…

  15. Proprioceptive bimanual test in intrinsic and extrinsic coordinates.

    Science.gov (United States)

    Iandolo, Riccardo; Squeri, Valentina; De Santis, Dalia; Giannoni, Psiche; Morasso, Pietro; Casadio, Maura

    2015-01-01

    Is there any difference between matching the position of the hands by asking the subjects to move them to the same spatial location or to mirror-symmetric locations with respect to the body midline? If the motion of the hands were planned in the extrinsic space, the mirror-symmetric task would imply an additional challenge, because we would need to flip the coordinates of the target on the other side of the workspace. Conversely, if the planning were done in intrinsic coordinates, in order to move both hands to the same spot in the workspace, we should compute different joint angles for each arm. Even if both representations were available to the subjects, the two tasks might lead to different results, providing some cue on the organization of the "body schema". In order to answer such questions, the middle fingertip of the non-dominant hand of a population of healthy subjects was passively moved by a manipulandum to 20 different target locations. Subjects matched these positions with the middle fingertip of their dominant hand. For most subjects, the matching accuracy was higher in the extrinsic modality both in terms of systematic error and variability, even for the target locations in which the configuration of the arms was the same for both modalities. This suggests that the matching performance of the subjects could be determined not only by proprioceptive information but also by the cognitive representation of the task: expressing the goal as reaching for the physical location of the hand in space is apparently more effective than requiring to match the proprioceptive representation of joint angles.

  16. Fabrication,property characterization and toughening mechanism of HA-ZrO2(CaO)/316L fibre composite biomaterials

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    HA-ZrO2(CaO)/316L fibre composites were successfully fabricated with vacuum sintering method and their properties and toughening mechanism were studied. The results showed that HA-ZrO2(CaO)/316L fibre biocomposite having 20 vol% fibres had optimal comprehensive properties with bending strength, Young’s modulus, fracture toughness and relative density equal to 140.1 MPa, 117.8 GPa, 5.81 MPa·m1/2 and 87.1%, respectively. The research also addressed that different volume ratios of the composites led to different metallographic microstructures, and that metallographic morphologies change regularly with volume ratios of the composites. 316L fibres were distributed randomly and evenly in the composites and the integration circumstance of the two phases was very well since there were no obvious flaws or pores in the composites. Two toughening mechanisms including ZrO2 phase transformation toughening mechanism and fibre pulling-out toughening mechanism existed in the compsites with the latter being the main toughening mechanism.

  17. Mesomechanism of steel fiber reinforcement and toughening of reactive powder concrete

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Reactive powder concrete (RPC) is a novel cement-based composite material with ultra-high strength. Embedding a certain amount of short steel fibers in the matrix can improve the RPC's toughness and overcome the disadvantage of high brittleness. In this paper, a number of direct uniaxial tension tests have been carried out with '8-shape' RPC200 specimens. The bond-slip process, mesoscopic structural variation and mechanical characteristics of a fiber pullout of the matrix have been investigated using the real-time SEM loading system and CCD observation techniques. The influence of the volume of embedded short steel fibers in matrix on the mesoscopic morphology of attachments on the surface of a pulled individual fiber, the initial cracking force, the ultimate pullout force, interfacial bond strength and the pullout rupture energy have been analyzed. A general formulation relating these quantities to the volume of fibers in matrix has been proposed. The components comprising the interfacial bond strength have been outlined. In addition, the contribution that fibers make to enhance and toughen the reactive powder concrete has been discussed. It is shown that there exists an optimal threshold of fiber volume ρv, opt =1.5% at which the bond performance of a fiber pullout of RPC behaves best.

  18. Effects of Cryogenic Temperature on Fracture Toughness of Core-Shell Rubber (CSR) Toughened Epoxy Nanocomposites

    Science.gov (United States)

    Wang, J.; Cannon, S. A.; Magee, D.; Schneider, J. A.

    2008-01-01

    This study investigated the effects of core-shell rubber (CSR) nanoparticles on the mechanical properties and fracture toughness of an epoxy resin at ambient and liquid nitrogen (LN2) temperatures. Varying amounts of Kane Ace MX130 toughening agent were added to a commercially available EPON 862/Epikure W epoxy resin. Elastic modulus was calculated using quasi-static tensile data. Fracture toughness was evaluated by the resulting breaking energy measured in Charpy impact tests conducted on an instrumented drop tower. The size and distribution of the CSR nanoparticles were characterized using Transmission Electron Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). Scanning Electron Microscopy (SEM) was used to study the fracture surface morphology. The addition of the CSR nanoparticles increased the breaking energy with negligible change in elastic modulus and ultimate tensile stress (UTS). At ambient temperature the breaking energy increased with increasing additions of the CSR nanoparticles, while at LN2 temperatures, it reached a maximum at 5 wt% CSR concentration. KEY WORDS: liquid nitrogen (LN2) properties, fracture toughness, core-shell rubber (CSR).

  19. Toughening of Epoxies: Novel Self-Assembling Block Copolymers Versus Traditional Telechelic Oligomers

    Science.gov (United States)

    Bacigalupo, Lauren N.

    Epoxy resins are commonly utilized because of their adhesive capacity and high strength. However, epoxies are inherently brittle; so much research has been dedicated to improving their fracture toughness. This study will focus on a comparing a traditional telechelic oligomer, CTBN, and a novel self-assembling block copolymer, SBM, as it relates to improving the fracture toughness of a lightly crosslinked epoxy system. After characterizing the modified systems for fracture toughness, mechanical and thermal properties, namely yield stress and the glass transition, will be determined in order to discern the impact these modifiers have on the overall properties of the blend. TEM, SEM and TOM techniques will be utilized for characterizing morphology, fractography and subsurface damage, respectively. Once this was accomplished, it was deduced that the toughening mechanisms of CTBN and SBM-modified epoxies are very similar. The main difference between the two is that the inherent structure of SBM allows the SBM-modified epoxy to retain its compressive yield strength. This, consequently, makes SBM ideal for thin bondline applications in the industrial adhesive and/or electronics industry.

  20. Curing and toughening of epoxy resins with phosphorus containing monomers and polymers

    Energy Technology Data Exchange (ETDEWEB)

    Park, Y.R.; Park, I.Y.; Yoon, T.H. [Kwangji Inst. of Science and Technology, Kwangju (Korea, Republic of)] [and others

    1996-12-31

    Epoxy resins have been utilized in many areas, from house holds to airplanes, for the past several decades due to some exceptional properties such as low cost, good mechanical properties and excellent adhesive properties. However, low fracture toughness and flame resistance of epoxy resins have limited their applicability. Therefore, enhancing those properties have been of great interest to many researchers and scientists. As introduced by McGrath and co-workers in 1980s, the reactive thermoplastic polymers have proven to be an excellent toughener for improving not only fracture toughness but also adhesive properties without sacrificing thermo-mechanical properties and chemical resistance. Flame retardency could be improved by adding flame retardent additives which are divided into two groups; additives and reactives. However, among the additives, halogen compounds are known to be toxic gas generator and ozone depleter. Moreover, additives could be potentially leached out of the material, while reactives are inferior to additives. Recently, a reactive type phosphine oxide containing flame retardants have been introduced by McGrath and co-workers and proven to be an excellent flame retardant. In this paper, phospine oxide containing monomers were prepared and utilized as curing agents for expoxy resins, and starting materials for the polymers.

  1. Effects of Cryogenic Temperature on Fracture Toughness of Core-Shell Rubber (CSR) Toughened Epoxy Nanocomposites

    Science.gov (United States)

    Wang, J.; Cannon, S. A.; Magee, D.; Schneider, J. A.

    2008-01-01

    This study investigated the effects of core-shell rubber (CSR) nanoparticles on the mechanical properties and fracture toughness of an epoxy resin at ambient and liquid nitrogen (LN2) temperatures. Varying amounts of Kane Ace MX130 toughening agent were added to a commercially available EPON 862/Epikure W epoxy resin. Elastic modulus was calculated using quasi-static tensile data. Fracture toughness was evaluated by the resulting breaking energy measured in Charpy impact tests conducted on an instrumented drop tower. The size and distribution of the CSR nanoparticles were characterized using Transmission Electron Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). Scanning Electron Microscopy (SEM) was used to study the fracture surface morphology. The addition of the CSR nanoparticles increased the breaking energy with negligible change in elastic modulus and ultimate tensile stress (UTS). At ambient temperature the breaking energy increased with increasing additions of the CSR nanoparticles, while at LN2 temperatures, it reached a maximum at 5 wt% CSR concentration. KEY WORDS: liquid nitrogen (LN2) properties, fracture toughness, core-shell rubber (CSR).

  2. Isocyanate-terminated Polyethers Toughened Epoxy Resin: Chemical Modification, Thermal Properties, and Mechanical Strength

    Institute of Scientific and Technical Information of China (English)

    CAI Haopeng; WANG Jun; WANG Xiang; XU Renxin

    2007-01-01

    The toughening of the diglycidyl ether of bisphenol A epoxy resin with isocyanateterminated polyethers (ITPE) was investigated. The progress of the reaction and the structural changes during modification process were studied using FTIR spectroscopy. The studies support the proposition that TDI (tolylene diisocyanate) acts as a coupling agent between the epoxy and polyethers, forming a urethane linkage with the former and the latter, respectively. Me THPA-cured ER/ITPs blends were characterized using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). It is indicated the glass transition temperature (Tg) of systems was lower than the Tg of pure epoxy resin and overfull ITPE separated from the modified epoxy resin and formed another phase at an ITPE-content of more than 10wt%. The thermal stability was decreased by the introduction of ITPE. The impact strength and the flexural strength of the cured modifiedepoxy increased with increasing the ITPE content and a maximum plateau value of about 24.03 kJ/m2 and 130.56 MPa was measured in 10wt% ITPE. From scanning electron microscopy (SEM) studies of the fractrue surfaces of ER/ITPE systems, the nature of the micromechanisms responsible for the increases in toughness of the systems was identified.

  3. Surface Roughness Prediction Model using Zirconia Toughened Alumina (ZTA) Turning Inserts: Taguchi Method and Regression Analysis

    Science.gov (United States)

    Mandal, Nilrudra; Doloi, Biswanath; Mondal, Biswanath

    2016-01-01

    In the present study, an attempt has been made to apply the Taguchi parameter design method and regression analysis for optimizing the cutting conditions on surface finish while machining AISI 4340 steel with the help of the newly developed yttria based Zirconia Toughened Alumina (ZTA) inserts. These inserts are prepared through wet chemical co-precipitation route followed by powder metallurgy process. Experiments have been carried out based on an orthogonal array L9 with three parameters (cutting speed, depth of cut and feed rate) at three levels (low, medium and high). Based on the mean response and signal to noise ratio (SNR), the best optimal cutting condition has been arrived at A3B1C1 i.e. cutting speed is 420 m/min, depth of cut is 0.5 mm and feed rate is 0.12 m/min considering the condition smaller is the better approach. Analysis of Variance (ANOVA) is applied to find out the significance and percentage contribution of each parameter. The mathematical model of surface roughness has been developed using regression analysis as a function of the above mentioned independent variables. The predicted values from the developed model and experimental values are found to be very close to each other justifying the significance of the model. A confirmation run has been carried out with 95 % confidence level to verify the optimized result and the values obtained are within the prescribed limit.

  4. Epoxy Resins Toughened with Surface Modified Epoxidized Natural Rubber Fibers by One-Step Electrospinning.

    Science.gov (United States)

    Kim, Joo Ran; Kim, Jung J

    2017-04-27

    Epoxidized natural rubber fibers (ERFs) are developed through one-step electrospinning and directly deposited into epoxy resins without collecting and distributing of fibers. The shape of ERFs shows rough surface due to different evaporation rate of solvent mixture consisting of chloroform and dichloromethane and the average diameter of ERFs is 6.2 µm. The increase of ERFs loading from 0 to 20 wt % into the epoxy resin increases the fracture strain significantly from 1.2% to 13% and toughness from 0.3 MPa to 1.9 MPa by a factor of 7. However, the tensile strength and Young's modulus decrease about 34% from 58 MPa to 34 MPa and from 1.4 GPa to 0.9 GPa, respectively. Due to the crosslinking reactions between oxirane groups of ERFs and amine groups in the resin, surface roughness and the high aspect ratio of ERFs, ERFs result in more effective toughening effect with the minimum loss of tensile properties in epoxy resins.

  5. Ballistic Performance of Alumina and Zirconia-toughened Alumina Against 7.62 Armour Piercing Projectile

    Directory of Open Access Journals (Sweden)

    S G. Savio

    2014-09-01

    Full Text Available A study was carried out to compare the ballistic performance of high purity alumina and zirconia-toughened alumina (ZTA using depth of penetration (DoP test configuration against 7.62 mm armour piercing (AP ammunition. The effect of tile thickness on the differential efficiency factor (DEF was studied for tile thickness in the range of 3 mm to 6 mm for alumina tiles and 3 mm to 5 mm for ZTA tiles. The DEF is found to increase as tile thickness increases. An analysis on the failed shots showed that the residual shot weight does not follow a single linear relationship with ceramic tile thickness unlike the residual DoP for all thicknesses of tiles. Post-ballistic analysis on ceramic powder for particle size distribution was carried out and the results are presented.Defence Science Journal, Vol. 64, No. 5, September 2014, pp.477-483, DOI:http://dx.doi.org/10.14429/dsj.64.6745

  6. Fatigue Performance and Multiscale Mechanisms of Concrete Toughened by Polymers and Waste Rubber

    Directory of Open Access Journals (Sweden)

    Bo Chen

    2014-01-01

    Full Text Available For improving bending toughness and fatigue performance of brittle cement-based composites, two types of water-soluble polymers (such as dispersible latex powder and polyvinyl alcohol powder and waste tire-rubber powders are added to concrete as admixtures. Multiscale toughening mechanisms of these additions in concretes were comprehensively investigated. Four-point bending fatigue performance of four series concretes is conducted under a stress level of 0.70. The results show that the effects of dispersible latex powder on bending toughness and fatigue life of concrete are better than those of polyvinyl alcohol powder. Furthermore, the bending fatigue lives of concrete simultaneously containing polymers and waste rubber powders are larger than those of concrete with only one type of admixtures. The multiscale physics-chemical mechanisms show that high bonding effect and high elastic modulus of polymer films as well as good elastic property and crack-resistance of waste tire-rubber powders are beneficial for improving bending toughness and fatigue life of cementitious composites.

  7. Structure and properties of highly toughened biodegradable polylactide/ZnO biocomposite films.

    Science.gov (United States)

    Jayaramudu, J; Das, Kunal; Sonakshi, M; Siva Mohan Reddy, G; Aderibigbe, B; Sadiku, Rotimi; Sinha Ray, Suprakas

    2014-03-01

    Zinc oxide (ZnO) powder was investigated in terms of its use as filler in order to improve the inherent properties of PLA. Biocomposite films of PLA with different loadings of ZnO were prepared by solution casting method. Morphological analyses using SEM and POM showed that the ZnO particles were well dispersed at low ZnO loading, with starfish-like morphology. However, ZnO agglomeration was found at higher ZnO loadings. Tensile testing showed improvements in strength and a moderate improvement in toughness at 2 wt% ZnO loading. This is consistent with the homogeneous dispersion of ZnO particles in the PLA matrix. ZnO particles incorporation improved the thermal stability of PLA. In summary, ZnO particles were shown to have the potential as a toughener in the preparation of biocomposites with better integrity, although other approaches, such as the use of compatibilizer in the surface modification of ZnO will be needed for the concurrent improvement of PLA properties.

  8. Ethylene-octene copolymer (POE toughened polyamide 6/polypropylene nanocomposites: Effect of POE maleation

    Directory of Open Access Journals (Sweden)

    2009-05-01

    Full Text Available Ethylene-octene elastomer (POE and ethylene-octene elastomer grafted maleic anhydride (POEgMAH toughened nanocomposites of polyamide 6/polypropylene (PA6/PP containing 4 wt% organophilic modified montmorillonite (MMT were produced by melt compounding followed by injection moulding. The PA6/PP composition was kept constant (PA6/PP = 70/30 parts while the elastomer (either POE or POEgMAH content varied between 5 and 20 wt%. PP grafted maleic anhydride (PPgMAH was used to compatibilize the blend system. The impact strength of the nanocomposite system was examined by the conventional Izod impact test at room temperature (RT. In addition, linear elastic fracture mechanics (LEFM approach was used to study the fracture response of the notched three point bending type specimens at room temperature (RT and –40°C. Fracture surfaces of the broken specimens were examined using scanning electron microscopy. The results show that while POEgMAH can remarkably improve the compatibility between PA6 and the elastomer thus increasing the toughness, the unmodified POE has less significant contribution to PA6/PP/organoclay toughness. Elastomer domains of POEgMAH show a finer and more uniform dispersion than that of POE in the PA6/PP/organoclay matrix. It is also observed that the toughness increased with the increasing elastomer concentration for both unmaleated and maleated POE.

  9. Dynamic Mechanical Properties and Fracture Surface Morphologies of Core-Shell Rubber (CSR) Toughened Epoxy at Liquid Nitrogen (Ln2) Temperatures

    Science.gov (United States)

    Wang, J.; Magee, D.; Schneider, J. A.

    2009-01-01

    The dynamic mechanical properties and fracture surface morphologies were evaluated for a commercial epoxy resin toughened with two types of core-shell rubber (CSR) toughening agents (Kane Ace(Registered TradeMark) MX130 and MX960). The impact resistance (R) was evaluated by the resulting breaking energy measured in Charpy impact tests conducted on an instrumented drop tower. The resulting fracture surface morphologies were examined using Scanning Electron Microscopy (SEM). Fractographic observations of the CSR toughened epoxy tested at ambient temperature, showed a fracture as characterized by slender dendrite textures with large voids. The increasing number of dendrites and decreasing size of scale-like texture with more CSR particles corresponded with increased R. As the temperature decreased to Liquid Nitrogen (LN 2), the fracture surfaces showed a fracture characterized by a rough, torn texture containing many river markings and deep furrows.

  10. Effect of rod-like grain on properties and toughening mechanism of 3Y-TZP/Al2O3 ceramics

    Institute of Scientific and Technical Information of China (English)

    RONG Shou-fan; JI Ze-sheng; ZHU Yong-chang; ZHANG Jing-qiang

    2008-01-01

    In-situ rod-like Al2O3 grain was prepared by adding CAS multiphase additives under the sintering condition of 30 MPa, 1 550 ℃ and 1 h. The sintering behaviors, microstructure, toughening mechanism and access of Al2O3 ceramics were investigated by SEM, EDS and WDW omnipotent electronic mechanical testing machine, etc, and the crack propagating model of cylindrical crystal/3Y-TZP composite toughening Al2O3 ceramics was established. The results show that the composite additives prompt the anisotropic growth of Al2O3 grain, which strengthens toughening effect of 3Y-TZP in 3Y-TZP/Al2O3 composite ceramics. Moreover, the experimental material density is near to theoretical density, bending strength is 556.35 MPa, and fracture toughness is 6.73 MPa·m1/2. The mechanical properties of the materials are obviously improved.

  11. Hötorksanläggning i södra Finland – planering och utvärdering av lönsamhet

    OpenAIRE

    Wikner, Mats

    2015-01-01

    Syftet med föreliggande arbete är dels att undersöka vilka olika alternativ som finns för att bygga en hötork till en gård i Kyrkslätt i södra Finland, dels att utvärdera hötorkens eventuella lönsamhet. Arbetet har karaktären av en fallstudie, i den meningen att lönsamhetsberäkningarna snarast gäller för den specifika modellgården, där det i dagsläget bedrivs hästverksamhet och spannmålsodling. Gården har 65 hästar och 75 ha odlingsmark. Arbetet bygger på intervjuer (med tillverkare och ...

  12. 普氏野马与两种新疆地方品种马的ELA-DRA*exon2的多态性分析%Polymorphisms of the Gene ELA-DRA * exon 2 in Przewalski's Horse (Equus Przewalskii) and Two Kinds of Xinjiang Local Breeds

    Institute of Scientific and Technical Information of China (English)

    于丽娟; 恩特马克; 凌英会; 马月辉; 马合木提·哈力克

    2011-01-01

    To understand the polymorphism and allele frequency distribution of ELA-DRA * exon2 in Przewalski,s horse(Equus PrzewaLskii) , Kazakh and Yanqi horse, ELA-DRA * exon2 in three types of horses was genotyped by PCR-SSCP methods. Both the nucleotide and the amino acid sequences of the different alleles were analyzed in these horses. The results showed that seven genotypes were detected in 127 horses: three homozygotes named AA, BB and CC, four heterozygotes named AB, BC, AC and AD. AA genotype was dominant in Kazakh and Yanqi horses.CC was the dominant genotype in Przewalski's horse(Equus Przewalskii). The chi-square analysis suggested that the allele and genotype frequencies were in Hardy-Weinberg equilibrium in the three horse types. The analysis of PIC and He showed that the three horse types belonged to intermediate polymorphism. The values of PIC and He in Przewalski's horse(Equus Przewalskii)were lower than that in Kazakh and Yanqi horses.%为了解普氏野马、哈萨克马与焉耆马的ELA-DRA*exon2的多态性以及等位基因频率分布.本研究采用PCR-SSCP技术对普氏野马、哈萨克马与焉耆马的ELA-DRA*exon2进行分型,并对不同等位基因进行核苷酸与氨基酸分析.结果显示:127匹马中共出现7种基因型,3种纯合子分别记为AA、BB、CC;4种杂合子分别记为AB、AC、BC、AD.AA基因型为哈萨克马与焉耆马的优势基因型,普氏野马以CC基因型为主.经x2检验后,3种类型马的等位基因频率和基因型频率均处于Hardy-Weinberg平衡状态.PIC值与He值分析表明,3种类型马均属于中度多态,且普氏野马的PIC值与He值比哈萨克马与焉耆马低.

  13. Characterization of major histocompatibility complex (MHC DRB exon 2 and DRA exon 3 fragments in a primary terrestrial rabies vector (Procyon lotor.

    Directory of Open Access Journals (Sweden)

    Sarrah Castillo

    Full Text Available The major histocompatibility complex (MHC presents a unique system to explore links between genetic diversity and pathogens, as diversity within MHC is maintained in part by pathogen driven selection. While the majority of wildlife MHC studies have investigated species that are of conservation concern, here we characterize MHC variation in a common and broadly distributed species, the North American raccoon (Procyon lotor. Raccoons host an array of broadly distributed wildlife diseases (e.g., canine distemper, parvovirus and raccoon rabies virus and present important human health risks as they persist in high densities and in close proximity to humans and livestock. To further explore how genetic variation influences the spread and maintenance of disease in raccoons we characterized a fragment of MHC class II DRA exon 3 (250 bp and DRB exon 2 (228 bp. MHC DRA was found to be functionally monomorphic in the 32 individuals screened; whereas DRB exon 2 revealed 66 unique alleles among the 246 individuals screened. Between two and four alleles were observed in each individual suggesting we were amplifying a duplicated DRB locus. Nucleotide differences between DRB alleles ranged from 1 to 36 bp (0.4-15.8% divergence and translated into 1 to 21 (1.3-27.6% divergence amino acid differences. We detected a significant excess of nonsynonymous substitutions at the peptide binding region (P = 0.005, indicating that DRB exon 2 in raccoons has been influenced by positive selection. These data will form the basis of continued analyses into the spatial and temporal relationship of the raccoon rabies virus and the immunogenetic response in its primary host.

  14. 基于ZEMAX的仿生DRA复眼阵列的仿真与分析%Simulation and Analysis of the Bionic DRA Compound Eyes Based on the ZEMAX Software

    Institute of Scientific and Technical Information of China (English)

    曹卫达; 唐军; 王晨光; 丁宇凯; 王飞; 翟超; 刘俊

    2014-01-01

    昆虫 DRA 区域复眼阵列可以接收天空偏振光,并将包含其中的偏振信息提取出来,使昆虫复眼具备导航的功能;根据生物解剖学得出的DRA复眼阵列结构,提出一种采用MEMS工艺制作的简化阵列结构,其体积小、质量轻、视角大,通过拼合可以实现180°天空区域的偏振信息的完整获取;并在ZEMAX中建立了DRA复眼阵列模型,通过仿真分析得出此DRA复眼阵列模型采用的材料及结构合理,可以用来检测天空光偏振分布模式(E-矢量分布模式)。%Compound array in the DRA area of insects can receive the polarized light in the sky and abstract its polarization information, which enable the insects to navigate. According to the structure of DRA compound array elicited from biological anatomy, we put forward a kind of simplified array architecture made by MEMS technology, which has small volume, light weight, large visual angle and can perfectly obtain the polarization information of the sky all through 180° by combination. Then, we build the model of DRA compound array in ZEMAX, and educe that the material and structure of the model of DRA compound array are reasonable and can be used to detect the polarization information of the sky light effectively.

  15. Distinguishing subtypes of extrinsic motivation among people with mild to borderline intellectual disability.

    Science.gov (United States)

    Frielink, N; Schuengel, C; Embregts, P

    2017-07-01

    According to self-determination theory, motivation is ordered in types, including amotivation, extrinsic motivation and intrinsic motivation. Self-determination theory defines four subtypes of extrinsic motivation: external motivation, introjected motivation, identified motivation and integrated motivation. Although it has been argued theoretically that the different types of motivation are universally applicable, Reid et al. () proposed a dichotomy of broad subtypes of extrinsic motivation for people with intellectual disability (ID) due to their cognitive limitations. The current study challenges this proposal by testing whether the four subtypes of extrinsic motivation can be differentiated among people with ID as well. The subtypes of extrinsic motivation were measured using two adapted versions of the Self-Regulation Questionnaire, one regarding exercise and one regarding support. In total, 186 adults with mild to borderline ID participated in the study. Results supported the distinction between the four subtypes of extrinsic motivation regarding both exercise and support. In addition, the correlation coefficients supported a quasi-simplex pattern of correlations among the subtypes, indicating that adjacent subtypes were more closely related than non-adjacent subtypes. Moreover, the study showed sufficient Cronbach's alphas and test-retest reliabilities for early stage research. Overall, the results of the current study provide initial evidence for the universality of the four subtypes of extrinsic motivation across populations with and without ID. © 2017 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disibilities and John Wiley & Sons Ltd.

  16. Intrinsic and Extrinsic Motivation Among Adolescent Ten-Pin Bowlers in Kuala Lumpur, Malaysia

    Directory of Open Access Journals (Sweden)

    Teo Eng-Wah

    2015-03-01

    Full Text Available Motivation has long been associated with sports engagement. However, to date no research has been performed to understand the domain of motivation among ten-pin bowlers. The purpose of this study was to investigate different types of motivation (i.e., intrinsic vs. extrinsic based on self-determination theory from the perspective of gender and the bowler type (competitive vs. casual. A total of 240 bowlers (104 male, 136 female; 152 competitive, 88 casual with a mean age of 16.61 ± 0.78 years were recruited in Kuala Lumpur. The Sport Motivation Scale, a 28-item self-report questionnaire measuring seven subscales (i.e., intrinsic motivation to know, intrinsic motivation to accomplish, intrinsic motivation to experience stimulation, extrinsic motivation to identify regulation, extrinsic motivation for introjection regulation, extrinsic motivation to external regulation, and amotivation was administered. Results showed significant differences (t=10.43, df=239, p=0.01 between total scores of intrinsic and extrinsic motivation among tenpin bowlers. There were significant gender differences with respect to intrinsic motivation to know, intrinsic motivation to accomplish, intrinsic motivation to experience stimulation, and extrinsic motivation to identify regulation. However, no significant bowler type differences were found for either the intrinsic (t=-1.15, df=238, p=0.25 or extrinsic (t=-0.51, df=238, p=0.61 motivation dimensions. In conclusion, our study demonstrated substantial intrinsic motivation for gender effects, but no bowler type effects among adolescent ten-pin bowlers.

  17. Intrinsic and extrinsic motivation among adolescent ten-pin bowlers in kuala lumpur, malaysia.

    Science.gov (United States)

    Teo, Eng-Wah; Khoo, Selina; Wong, Rebecca; Wee, Eng-Hoe; Lim, Boon-Hooi; Rengasamy, Shabesan Sit

    2015-03-29

    Motivation has long been associated with sports engagement. However, to date no research has been performed to understand the domain of motivation among ten-pin bowlers. The purpose of this study was to investigate different types of motivation (i.e., intrinsic vs. extrinsic) based on self-determination theory from the perspective of gender and the bowler type (competitive vs. casual). A total of 240 bowlers (104 male, 136 female; 152 competitive, 88 casual) with a mean age of 16.61 ± 0.78 years were recruited in Kuala Lumpur. The Sport Motivation Scale, a 28-item self-report questionnaire measuring seven subscales (i.e., intrinsic motivation to know, intrinsic motivation to accomplish, intrinsic motivation to experience stimulation, extrinsic motivation to identify regulation, extrinsic motivation for introjection regulation, extrinsic motivation to external regulation, and amotivation) was administered. Results showed significant differences (t=10.43, df=239, p=0.01) between total scores of intrinsic and extrinsic motivation among ten-pin bowlers. There were significant gender differences with respect to intrinsic motivation to know, intrinsic motivation to accomplish, intrinsic motivation to experience stimulation, and extrinsic motivation to identify regulation. However, no significant bowler type differences were found for either the intrinsic (t=-1.15, df=238, p=0.25) or extrinsic (t=-0.51, df=238, p=0.61) motivation dimensions. In conclusion, our study demonstrated substantial intrinsic motivation for gender effects, but no bowler type effects among adolescent ten-pin bowlers.

  18. Bridging the gap between extrinsic and intrinsic motivation in the cognitive remediation of schizophrenia.

    Science.gov (United States)

    Silverstein, Steven M

    2010-09-01

    An important development in cognitive remediation of schizophrenia is a focus on motivation. However, following a distinction between the concepts of intrinsic motivation (IM) and extrinsic motivation, discussions of IM-based methods have downplayed or misrepresented the role that extrinsic rewards can, and actually do, serve to promote positive treatment outcomes in cognitive remediation. Therefore, the purpose of this article is to explore the rationale for using techniques incorporating extrinsic rewards into cognitive treatment of people with schizophrenia. To do this, evidence is presented on each of the following points: (1) there is a long history of research demonstrating that delivery of extrinsic reward is associated with positive outcomes in both behavioral and cognitive rehabilitation; (2) basic human brain systems respond strongly to tangible rewards, and this can directly enhance attention, working memory, and other cognitive functions; (3) nearly all data on the negative effects of extrinsic reward on IM have come from studies of healthy children and adults in school or work settings who have adequate IM for target tasks; these findings do not generalize well to cognitive remediation settings for people with schizophrenia, who often have abnormally low levels of IM and low base rates of attentive behaviors; and (4) in real-world situations, cognitive remediation interventions already utilize a combination of intrinsic and extrinsic reinforcers. Future studies are needed to clarify state and trait factors responsible for individual differences in the extent to which extrinsic rewards are necessary to set the conditions under which IM can develop.

  19. On the toughening of brittle materials by grain bridging:promoting intergranular fracture through grain angle, strength, andtoughness

    Energy Technology Data Exchange (ETDEWEB)

    Foulk III, J.W.; Johnson, G.C.; Klein, P.A.; Ritchie, R.O.

    2007-11-15

    The structural reliability of many brittle materials such asstructural ceramics relies on the occurrence of intergranular, as opposedto transgranular, fracture in order to induce toughening by grainbridging. For a constant grain boundary strength and grain boundarytoughness, the current work examines the role of grain strength, graintoughness, and grain angle in promoting intergranular fracture in orderto maintain such toughening. Previous studies have illustrated that anintergranular path and the consequent grain bridging process can bepartitioned into five distinct regimes, namely: propagate, kink, arrest,stall and bridge. To determine the validity of the assumed intergranularpath, the classical penentration/deflection problem of a crack impingingon an interface is reexamined within a cohesive zone framework forintergranular and transgranular fracture. Results considering both modesof propagation, i.e., a transgranular and intergranular path, reveal thatcrack-tip shielding is a natural outcome of the cohesive zone approach tofracture. Cohesive zone growth in one mode shields the opposing mode fromthe stresses required for cohesive zone initiation. Although stablepropagation occurs when the required driving force is equivalent to thetoughness for either transgranular or intergranular fracture, the mode ofpropagation depends on the normalized grain strength, normalized graintoughness, and grain angle. For each grain angle, the intersection ofsingle path and multiple path solutions demarcates "strong" grains thatincrease the macroscopic toughness and "weak" grains that decrease it.The unstable transition to intergranular fracture reveals that anincreasinggrain toughness requires a growing region of the transgranularcohesive zone be at and near the peak cohesive strength. The inability ofthe body to provide the requisite stress field yields an overdriven andunstable configuration. The current results provide restrictions for theachievement of substantial toughening

  20. Degradation of alumina and zirconia toughened alumina (ZTA) hip prostheses tested under microseparation conditions in a shock device

    CERN Document Server

    Uribe, Juliana; Gremillard, Laurent; Reynard, Bruno

    2013-01-01

    This paper considers the degradation of alumina and zirconia toughened alumina vs. alumina for hip implants. The materials are as assumed to be load bearing surfaces subjected to shocks in wet conditions. The load is a peak of force; 9 kN was applied over 15 ms at 2 Hz for 800,000 cycles. The volumetric wear and roughness are lower for ZTA than for alumina. The long ZTA ageing did not seem to have a direct influence on the roughness. The ageing increased the wear volumes of ZTA and it was found to have a higher wear resistance compared to alumina.

  1. Strengthening and Toughening Effect of Yttrium on Al2O3/TiCN Ceramic Tool Material

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The strengthening and toughening effect of yttrium on an advanced Al2O3/TiCN ceramic tool material was studied by means of SEM, TEM and energy spectrum analysis. Results showed that yttrium can react with the impurity elements such as W, Fe, Cr, etc. Thus, the interfaces between ceramic phases are purified and the interfacial binding strength is increased. As a result, the mechanical properties of the Al2O3/TiCN ceramic tool material reinforced with yttrium are improved significantly. In addition, the effect of yttrium on particle strengthening of the solid solution TiCN may partly contribute to the improvement of the mechanical properties.

  2. Intrinsic and extrinsic motivations for healthful dietary change in African Americans.

    Science.gov (United States)

    Satia, Jessie A; Galanko, Joseph A

    2007-01-01

    To describe associations of intrinsic and extrinsic motivations for dietary change with participant characteristics and current diet among African Americans. Cross-sectional survey of 658 African American adults in North Carolina provided information on intrinsic (self-image and health concerns) and extrinsic (social influence) motivation scales, participant characteristics, and diet. Most respondents considered it important to change their diet for health reasons; fewer were motivated by self-image or social influence. Motivation scales were significantly associated with demographic, behavioral, and psychosocial characteristics and fat, but not fruit/vegetable consumption, after adjustment for covariates (Pintrinsic and extrinsic motives may improve the effectiveness of dietary interventions in African Americans.

  3. Intrinsic and extrinsic motivational orientations in the competitive context: an examination of person-situation interactions.

    Science.gov (United States)

    Abuhamdeh, Sami; Csikszentmihalyi, Mihaly

    2009-10-01

    The current study examined Intrinsic Motivation Orientation and Extrinsic Motivation Orientation (Work Preference Inventory; Amabile, Hill, Hennessey, & Tighe, 1994) as potential trait-level moderators of the way Internet chess players responded to the intrinsic and extrinsic rewards of the chess games they played. On the basis of the defining characteristics of these 2 types of motivational orientations, we predicted that (a) Intrinsic Motivation Orientation would be associated with a stronger curvilinear relationship between challenge and enjoyment and (b) Extrinsic Motivation Orientation would be associated with a heightened affective responsivity to competitive outcome (i.e., winning vs. losing). Results supported the predictions. Implications of the findings are discussed.

  4. Measurements of extrinsic fluorescence in Intralipid and polystyrene microspheres

    Science.gov (United States)

    Du Le, Vinh Nguyen; Nie, Zhaojun; Hayward, Joseph E.; Farrell, Thomas J.; Fang, Qiyin

    2014-01-01

    The fluorescence of Intralipid and polystyrene microspheres with sphere diameter of 1 µm at a representative lipid and microsphere concentration for simulation of mucosal tissue scattering has not been a subject of extensive experimental study. In order to elucidate the quantitative relationship between lipid and microsphere concentration and the respective fluorescent intensity, the extrinsic fluorescence spectra between 360 nm and 650 nm (step size of 5 nm) were measured at different lipid concentrations (from 0.25% to 5%) and different microsphere concentrations (0.00364, 0.0073, 0.0131 spheres per cubic micrometer) using laser excitation at 355 nm with pulse energy of 2.8 µJ. Current findings indicated that Intralipid has a broadband emission between 360 and 650 nm with a primary peak at 500 nm and a secondary peak at 450 nm while polystyrene microspheres have a single peak at 500 nm. In addition, for similar scattering properties the fluorescence of Intralipid solutions is approximately three-fold stronger than that of the microsphere solutions. Furthermore, Intralipid phantoms with lipid concentrations ~2% (simulating the bottom layer of mucosa) produce up to seven times stronger fluorescent emission than phantoms with lipid concentration ~0.25% (simulating the top layer of mucosa). The fluoresence decays of Intralipid and microsphere solutions were also recorded for estimation of fluorescence lifetime. PMID:25136497

  5. [Pathologic diagnosis and clinical analysis of chronic extrinsic allergic alveolitis].

    Science.gov (United States)

    Diao, Xiao-li; Jin, Mu-lan; Dai, Hua-ping; Li, Xue; Wei, Ping; Zhang, Yun-gang

    2011-11-01

    To study the clinicopathologic features and diagnostic approach of chronic extrinsic allergic alveolitis (EAA). Seven cases of chronic EAA diagnosed by open lung biopsy or lung transplant were enrolled into the study. The clinical and pathologic features were analyzed and the literature was reviewed. There were altogether 4 men and 3 women. The age of the patients ranged from 30 to 65 years (mean = 48 years). All cases represented chronic form and five cases diagnosed by open lung biopsy also showed features of recent aggravation, leading to hospitalization. Four cases had known history of exposure to inciting gases, pollens and pets, and only 2 cases were positive for allergens. High-resolution CT scan showed ground-glass attenuation and reticular pattern that often had a patchy distribution and central predominance. Bronchoalveolar lavage analysis showed marked lymphocytosis, with CD4(+)/CD8(+) ratio less than 1. Lung function test demonstrated a restrictive ventilatory defect, with decreased compliance, reduced diffusion capacity and high airway obstruction. Five cases had open lung biopsy performed and two cases had undergone lung transplantation. Pathologic examination showed bronchiolocentric cellular interstitial pneumonia, interstitial fibrosis, non-caseating epithelioid granulomas, epithelioid histiocytic infiltrate in the respiratory bronchioles and intraluminal budding fibrosis. The five cases with open lung biopsy performed also showed neutrophilic infiltrate in the alveoli. The two lung transplant cases were complicated by severe fibrotic changes. Chronic EAA demonstrates characteristic pathologic features. Definitive diagnosis requires correlation with clinical and radiologic findings due to possible morphologic mimicry of other diffuse parenchymal lung diseases.

  6. An outbreak of extrinsic alveolitis at a car engine plant.

    Science.gov (United States)

    Dawkins, Paul; Robertson, Alastair; Robertson, Wendy; Moore, Vicky; Reynolds, John; Langman, Gerald; Robinson, Edward; Harris-Roberts, Joanne; Crook, Brian; Burge, Sherwood

    2006-12-01

    Twelve workers from a car engine-manufacturing plant presented with extrinsic allergic alveolitis (EAA), with heterogeneous clinical, radiological and pathological findings. They were exposed to metalworking fluids (MWF) that cooled, lubricated and cleaned the machines. They were characterized by history, examination, lung function testing, radiology, bronchoscopic lavage, lung biopsy and serology. Sera were tested for precipitins to a crude extract of used MWF and to reference cultures of bacteria suspected to be implicated. All were males and none were current smokers. All had dyspnoea, many had weight loss and cough, but only half had influenza-like symptoms. Only half had auscultatory crackles. Five had peak flow variability, four with an occupational component. There was overall restrictive spirometry, decreased lung volumes and reduced gas transfers. Ten had radiological evidence of interstitial lung disease. Seven (of eight) had lymphocytosis on bronchial lavage, including the two with inconclusive radiology. Seven (of 11) had lung biopsies showing inflammatory infiltrates, two with fibrosis and one with granulomas. Three (of 11) had strong positive precipitins to an extract of the used MWF from the plant. Molecular biological analysis of the MWF revealed Acinetobacter and Ochrobactrum. Precipitins to Acinetobacter were detected in seven of 11 workers tested (and four of 11 control workers). Precipitins to Ochrobactrum were detected in three of 11 workers tested (and three of 11 control workers). This is the largest series reported in Europe of EAA due to an aerosol of microbiologically contaminated MWF in heavy manufacturing industry.

  7. Effect of extrinsic curvature on quark--hadron phase transition

    CERN Document Server

    Heydari-Fard, Malihe

    2009-01-01

    The last phase transition predicted by the standard model of particle physics took place at the QCD scale $T\\sim200$ MeV when the universe was about $t\\sim10^{-5}$ seconds old and the Hubble radius was around 10 Km. In this paper, we consider the quark--hadron phase transition in the context of brane-world cosmology where our universe is a 3-brane embedded in a $m$-dimensional bulk and localization of matter on the brane is achieved by means of a confining potential. We study the behavior of the physical quantities relevant to the description of the early universe like the energy density, temperature and scale factor, before, during, and after the phase transition and investigate the effects of extrinsic curvature on the cosmological phase transition. We show that the brane-world effects reduce the effective temperature of the quark--gluon plasma and of the hadronic fluid. Finally, we discuss the case where the universe evolved through a mixed phase with a small initial supercooling and monotonically growing ...

  8. [Swimming pool lung -- extrinsic allergic alveolitis or mycobacterial disease?].

    Science.gov (United States)

    Koschel, D; Pietrzyk, C; Sennekamp, J; Müller-Wening, D

    2006-05-01

    There have been several recent reports of pulmonary disease resulting from exposure to Mycobacterium avium complex in indoor hot tubs. The disease is thought to be due either to infection or extrinsic allergic alveolitis (EAA). In this report we describe the case of a patient who developed episodes of fever, dyspnea and cough 4-6 hours after cleaning his indoor swimming pool. A diagnosis of EAA was made on finding a restrictive lung function pattern with gas exchange abnormalities, a predominant lymphocytosis in the bronchoalveolar lavage, diffuse ground-glass opacities in the lower lobes on high-resolution computer tomography, and specific IgG antibody activity to the swimming pool water. There was no precipitin reaction or specific IgG antibody activity to microbes extracted from the water. Interestingly, the water contained Mycobacterium avium complex (MAC) in huge amounts and in this case the histopathological features of the lung biopsy specimens differed from those seen in typical EAA, but were similar to those described in "hot tub lung" caused by mycobacteria. Solely by avoidance of cleaning the swimming pool, without any pharmacological treatment, the patient recovered completely within three months. To the best of our knowledge, this is the first report of EAA possibly associated with MAC exposure in a swimming pool environment.

  9. Enabling complex genetic circuits to respond to extrinsic environmental signals.

    Science.gov (United States)

    Hoynes-O'Connor, Allison; Shopera, Tatenda; Hinman, Kristina; Creamer, John Philip; Moon, Tae Seok

    2017-03-06

    Genetic circuits have the potential to improve a broad range of metabolic engineering processes and address a variety of medical and environmental challenges. However, in order to engineer genetic circuits that can meet the needs of these real-world applications, genetic sensors that respond to relevant extrinsic and intrinsic signals must be implemented in complex genetic circuits. In this work, we construct the first AND and NAND gates that respond to temperature and pH, two signals that have relevance in a variety of real-world applications. A previously identified pH-responsive promoter and a temperature-responsive promoter were extracted from the E. coli genome, characterized, and modified to suit the needs of the genetic circuits. These promoters were combined with components of the type III secretion system in Salmonella typhimurium and used to construct a set of AND gates with up to 23-fold change. Next, an antisense RNA was integrated into the circuit architecture to invert the logic of the AND gate and generate a set of NAND gates with up to 1168-fold change. These circuits provide the first demonstration of complex pH- and temperature-responsive genetic circuits, and lay the groundwork for the use of similar circuits in real-world applications. Biotechnol. Bioeng. 2017;9999: 1-6. © 2017 Wiley Periodicals, Inc.

  10. Intrinsic and extrinsic rewards in a nonformal environmental education program.

    Science.gov (United States)

    Price, Emily A; Vining, Joanne; Saunders, Carol D

    2009-09-01

    Humans are surrounded by threats to the environment, many of their own making. The severity of environmental problems will not decrease unless action is taken to develop and encourage greater environmentally responsible behavior (ERB) in the general populace. Environmental education (EE) is one method for strengthening precursors to ERB such as knowledge and attitudes, but research on the connection is currently unclear. In this paper we present the results of a study investigating the role played by rewards in encouraging ERB precursors for adults and children involved in a zoo-based Nature Swap program. We used semistructured interviews to question 91 participants, including 38 children, 38 adult guardians, and 15 staff members regarding the importance of rewards in the program. We content analyzed the interviews to identify and describe major themes and then coded them. We found that adult guardians and Play Partners perceived intrinsic and extrinsic rewards as aiding in maintaining motivation and interest in the nonformal Nature Swap program. In addition, both children and adult companion participants in the program mentioned strengthened precursors to ERB. Overall we found that adult companions perceived that children who participated in the program spent more quality time outdoors and had a heightened awareness of their surroundings as a result of program-based rewards. Implications for other EE and conservation education programs are discussed.

  11. Iterative procedure for camera parameters estimation using extrinsic matrix decomposition

    Science.gov (United States)

    Goshin, Yegor V.; Fursov, Vladimir A.

    2016-03-01

    This paper addresses the problem of 3D scene reconstruction in cases when the extrinsic parameters (rotation and translation) of the camera are unknown. This problem is both important and urgent because the accuracy of the camera parameters significantly influences the resulting 3D model. A common approach is to determine the fundamental matrix from corresponding points on two views of a scene and then to use singular value decomposition for camera projection matrix estimation. However, this common approach is very sensitive to fundamental matrix errors. In this paper we propose a novel approach in which camera parameters are determined directly from the equations of the projective transformation by using corresponding points on the views. The proposed decomposition allows us to use an iterative procedure for determining the parameters of the camera. This procedure is implemented in two steps: the translation determination and the rotation determination. The experimental results of the camera parameters estimation and 3D scene reconstruction demonstrate the reliability of the proposed approach.

  12. A Dynamic Assignment of Extrinsic Information Distribution by a Frequency Means for Iterative Turbo Decoder

    Institute of Scientific and Technical Information of China (English)

    YANGFengfan

    2003-01-01

    In this paper, a new strategy for iterative turbo decoding is proposed, where a Generalized Gaussian distribution (GGD) is applied to model the statistical distributions of the extrinsic information generated by the component decoders. An Euclidean distance criterion is also introduced to choose a most likely candidate of the extrinsic information distribution before the each constituent decoding by a novel frequency means. The simulation results show that performance of an iterative decoder with this new technique surpasses the conventional Gaussian solution for the extrinsic information under the same channel conditions. Meanwhile, the evolution process of the extrinsic information density function can be tracked from iteration to iteration in the sense of the proposed criterion.

  13. Topological implications of the extrinsic curvature for the cosmological constant problem

    CERN Document Server

    Capistrano, Abraao J S

    2014-01-01

    The concept of smooth deformation of a Riemannian manifolds associated with the extrinsic curvature is explained and applied to FLRW cosmology. We show that such deformation can be derived from an Einstein-Hilbert-like dynamical principle producing an observable effect in the sense of Noether. The Gupta equations are used to address the problem of the cosmological constant to provide the expression of the function $b(t)$ which is a consequence of the effect of extrinsic curvature. When using such a modification, we notice on how the extrinsic curvature compensates both quantitative and qualitative difference between $ \\Lambda$ and $\\rho_{\\; vac}$ due to the topological characteristics of the extrinsic geometry. It is also shown that the coincidence problem can be alleviated in this framework.

  14. The detrimental effects of extrinsic reinforcement on “Intrinsic motivation”

    Science.gov (United States)

    Dickinson, Alyce M.

    1989-01-01

    Extrinsic consequences have been criticized on the grounds that they decrease intrinsic motivation or internally initiated behavior. Two popular rationales for this criticism, Lepper's overjustification hypothesis (1981) and Deci's motivational theory (Deci & Ryan, 1985), are reviewed and the criticism is then redefined behaviorally. “Intrinsically controlled” behavior is defined as behavior maintained by response-produced reinforcers, and the question concerning extrinsic consequences is thus restated as follows: When behavior is maintained by response-produced stimuli, does extrinsic reinforcement decrease the reinforcing value of those stimuli? The empirical support for this detrimental effect is summarized briefly, and several possible explanations for the phenomenon are offered. Research results that reflect on the effect's generality and social significance are discussed next, with the conclusion that the effect is transient and not likely to occur at all if extrinsic rewards are reinforcing, noncompetitive, based on reasonable performance standards, and delivered repetitively. PMID:22478013

  15. Time is on my side: time, general mental ability, human capital, and extrinsic career success.

    Science.gov (United States)

    Judge, Timothy A; Klinger, Ryan L; Simon, Lauren S

    2010-01-01

    The present study linked general mental ability (GMA) to extrinsic career success using a multilevel framework that included time and 3 possible time-based mediators of the GMA-career success relationship. Results, based on a large national sample, revealed that over a 28-year period, GMA affected growth in 2 indicators of extrinsic career success (income and occupational prestige), such that the careers of high-GMA individuals ascended more steeply over time than those of low-GMA individuals. Part of the reason high-GMA individuals had steeper growth in extrinsic success over time was because they attained more education, completed more job training, and gravitated toward more complex jobs. GMA also moderated the degree to which within-individual variation in the mediating variables affected within-individual variation in extrinsic career success over time: Education, training, and job complexity were much more likely to translate into career success for more intelligent individuals.

  16. First principles studies of extrinsic and intrinsic defects in boron nitride nanotubes

    CSIR Research Space (South Africa)

    Mashapa, MG

    2012-10-01

    Full Text Available Spin polarized density functional theory has been used to investigate the structural stability and electronic properties of extrinsic and intrinsic defects in boron nitride nanotubes. Carbon substitutional defects under nitrogen rich and boron...

  17. Relationships of Parental Behavior to "Disadvantaged" Children's Intrinsic-Extrinsic Motivation for Task Striving

    Science.gov (United States)

    Solomon, Daniel; Houlihan, Kevin A.

    1972-01-01

    In this study, the relevance of striving situations to intrinsic and extrinsic motivation was manipulated by varying the degree of involvement in the child's performance displayed by the experimenter. (Authors)

  18. Intrinsic and Extrinsic Motivation Among Adolescent Ten-Pin Bowlers in Kuala Lumpur, Malaysia

    National Research Council Canada - National Science Library

    Eng-Wah Teo; Selina Khoo; Rebecca Wong; Eng-Hoe Wee; Boon-Hooi Lim; Shabesan Sit Rengasamy

    2015-01-01

    .... The purpose of this study was to investigate different types of motivation (i.e., intrinsic vs. extrinsic) based on self-determination theory from the perspective of gender and the bowler type...

  19. MECHANISMS UNDERLYING CREATIVE PERFORMANCE: EMPLOYEE PERCEPTIONS OF INTRINSIC AND EXTRINSIC REWARDS FOR CREATIVITY

    National Research Council Canada - National Science Library

    Hye Jung Yoon; Sun Young Sung; Jin Nam Choi

    2015-01-01

      In this study, we clarified some of the ambiguities in the rewards-creativity relationship by focusing on creative performance in organizations that is contingent on intrinsic and extrinsic rewards...

  20. Consolidation power of extrinsic rewards: reward cues enhance long-term memory for irrelevant past events.

    Science.gov (United States)

    Murayama, Kou; Kitagami, Shinji

    2014-02-01

    Recent research suggests that extrinsic rewards promote memory consolidation through dopaminergic modulation processes. However, no conclusive behavioral evidence exists given that the influence of extrinsic reward on attention and motivation during encoding and consolidation processes are inherently confounded. The present study provides behavioral evidence that extrinsic rewards (i.e., monetary incentives) enhance human memory consolidation independently of attention and motivation. Participants saw neutral pictures, followed by a reward or control cue in an unrelated context. Our results (and a direct replication study) demonstrated that the reward cue predicted a retrograde enhancement of memory for the preceding neutral pictures. This retrograde effect was observed only after a delay, not immediately upon testing. An additional experiment showed that emotional arousal or unconscious resource mobilization cannot explain the retrograde enhancement effect. These results provide support for the notion that the dopaminergic memory consolidation effect can result from extrinsic reward.

  1. Effect of Iron Morphology and Interfacial Bonding on the Toughening of Al2O3/Fe Composites

    Institute of Scientific and Technical Information of China (English)

    M.M.El-Sayed Seleman; Xudong SUN; Liang ZUO

    2001-01-01

    Two morphologically different composites comprising an alumina matrix and 20 vol. pct Fe particles have been fabricated by hot pressing technique. Two kinds of microstructures, i.e. a dispersive distribution of Fe particles and a network distribution of Fe particles in alumina matrix,have been produced. Both composites are tougher than the virgin alumina matrix. The fracture toughness of the composite with a network microstructure is much higher than the composite with a microstructure of dispersed particles. For the particulate dispersion microstructure, the main limitation to the toughening is the lack of plastic deformation of the ductile Fe due to the pull out of Fe particles, indicating weak bonding at the Al2O3/Fe interface. For the network microstructure composite, the gauge length of the ductile phase is much larger, allowing the ductile Fe to be stretched to failure between the crack faces. The weak bonding at Al2O3/Fe interface can promote partial debonding and contribute further to toughening in the network microstructure composite.

  2. Morphological Study on Room-Temperature-Cured PMMA-Grafted Natural Rubber-Toughened Epoxy/Layered Silicate Nanocomposite

    Directory of Open Access Journals (Sweden)

    N. Y. Yuhana

    2012-01-01

    Full Text Available A morphological study was conducted on ternary systems containing epoxy, PMMA-grafted natural rubber, and organic chemically modified montmorillonite (Cloisite 30B. Optical microscopy, transmission electron microscopy (TEM, scanning electron microscopy (SEM, energy dispersive X-ray (EDX, and wide-angle X-ray diffraction (WAXD analysis were used. The following four materials were prepared at room temperature: cured unmodified epoxy, cured toughened epoxy, cured unmodified epoxy/Cloisite 30B nanocomposites, and cured toughened epoxy/Cloisite 30B nanocomposites. Mixing process was performed by mechanical stirring. Poly(etheramine was used as the curing agent. The detailed TEM images revealed co-continuous and dispersed spherical rubber in the epoxy-rubber blend, suggesting a new proposed mechanism of phase separation. High-magnification TEM analysis showed good interactions between rubber and Cloisite 30B in the ternary system. Also, it was found that rubber particles could enhance the separation of silicates layers. Both XRD and TEM analyses confirmed that the intercalation of Cloisite 30B was achieved. No distinct exfoliated silicates were observed by TEM. Aggregates of layered silicates (tactoids were observed by SEM and EDX, in addition to TEM at low magnification. EDX analysis confirmed the presence of organic and inorganic elements in the binary and ternary epoxy systems containing Cloisite 30B.

  3. Integrated Ternary Bioinspired Nanocomposites via Synergistic Toughening of Reduced Graphene Oxide and Double-Walled Carbon Nanotubes.

    Science.gov (United States)

    Gong, Shanshan; Cui, Wei; Zhang, Qi; Cao, Anyuan; Jiang, Lei; Cheng, Qunfeng

    2015-12-22

    With its synergistic toughening effect and hierarchical micro/nanoscale structure, natural nacre sets a "gold standard" for nacre-inspired materials with integrated high strength and toughness. We demonstrated strong and tough ternary bioinspired nanocomposites through synergistic toughening of reduced graphene oxide and double-walled carbon nanotube (DWNT) and covalent bonding. The tensile strength and toughness of this kind of ternary bioinspired nanocomposites reaches 374.1 ± 22.8 MPa and 9.2 ± 0.8 MJ/m(3), which is 2.6 and 3.3 times that of pure reduced graphene oxide film, respectively. Furthermore, this ternary bioinspired nanocomposite has a high conductivity of 394.0 ± 6.8 S/cm and also shows excellent fatigue-resistant properties, which may enable this material to be used in aerospace, flexible energy devices, and artificial muscle. The synergistic building blocks with covalent bonding for constructing ternary bioinspired nanocomposites can serve as the basis of a strategy for the construction of integrated, high-performance, reduced graphene oxide (rGO)-based nanocomposites in the future.

  4. Tribology of improved transformation-toughened ceramics-heat engine test. Final report: DOE/ORNL Ceramic Technology Project

    Energy Technology Data Exchange (ETDEWEB)

    Lilley, E.; Rossi, G.A.; Pelletier, P.J. [Norton Co., Northboro, MA (United States). Advanced Ceramics Div.

    1992-04-01

    A short term study has been carried out to evaluate the suitability as cam roller followers of three ceria zirconia toughened aluminas and two yttria stabilized tetragonal zirconias (YTZPs) previously enhanced in programs supported by ORNL. Norton Si{sub 3}N{sub 4} (NBD-100) was also included in this study as a reference material, because it was known from work at Northwestern University that Si{sub 3}N{sub 4} to experienced little or no wear in this application, and NBD-100 is currently a successful commercial bearing material. The tribological studies were subcontracted to the Torrington Company. They found that in cam roller follower simulated tests that there was essentially no wear after 1 hour and 5 hours of testing detectable by weighing and concluded that all of these ceramics are, therefore, candidate materials. Because of the minute amounts of wear it was not possible to identify the wear mechanism or to make any correlations with the other physical properties which were evaluated such as MOR, K{sub IC} hardness, density and grain size. Phase transformation during rolling has been of interest in the tribology of zirconia contain materials. The least stable of the ceria zirconia toughened aluminas resulted in as much as 33% monoclinic phase after testing whereas the yttria stabilized (TTZ) contained very little of this transformed phase. The results of this study show that oxide materials can now be considered as candidates for cam roller followers in heat engines.

  5. Optical phase modulator utilizing a transparent piezofilm for use with the extrinsic fiber interferometer

    Science.gov (United States)

    Sudarshanam, V. S.; Claus, Richard O.

    1993-03-01

    A piezoelectnc polyvinylidene flouride (PVF2) film with transparent indium tin oxide electrode metallization is placed directly in the path of a single mode fiber output, to form an extrinsic optical interferometer. This device can be used concurrently with another extrinsic inteferometer on a fiber directional coupler to generate a carrier phase modulation on which the signal phase shift is superimposed. Experimental results of the induced phase shifting coefficient are presented for two arrangements of the piezofilm differing in their boundary clamping conditions.

  6. Sulfasalazine-induced extrinsic allergic alveolitis in a patient with psoriatic arthritis.

    Science.gov (United States)

    Woltsche, M; Woltsche-Kahr, I; Roeger, G M; Aberer, W; Popper, H

    2001-11-20

    We report the first case of a well defined extrinsic allergic alveolitis as a complication of sulfasalazine therapy in a patient treated for psoriatic arthritis. CT of the chest showed small nodular densities over both lungs, BAL demonstrated a highly active lymphocytic alveolitis and transbronchial biopsies revealed lymphoplasmocytic interstitial infiltration. Sulfasalazine as causative agent was proven by an inadvertent rechallenge three years later and a positive lymphocyte transformation test. sulfasalazine; psoriatic arthritis; extrinsic allergic alveolitis

  7. Multiexciton complex from extrinsic centers in AlGaAs epilayers on Ge and Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Sarti, F.; Muñoz Matutano, G.; Bauer, D.; Dotti, N.; Vinattieri, A.; Gurioli, M., E-mail: gurioli@lens.unifi.it [Dipartimento di Fisica e Astronomia, LENS and CNISM, Università di Firenze, Via Sansone 1, I-50019 Firenze (Italy); Bietti, S.; Sanguinetti, S. [Dipartimento di Scienza dei Materiali and L-NESS, Università di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Isella, G. [Dipartimento di Fisica and L-NESS, Politecnico di Milano, Via Anzani 42, 22100 Como (Italy)

    2013-12-14

    The multiexciton properties of extrinsic centers from AlGaAs layers on Ge and Si substrates are addressed. The two photon cascade is found both in steady state and in time resolved experiments. Polarization analysis of the photoluminescence provides clearcut attribution to neutral biexciton complexes. Our findings demonstrate the prospect of exploiting extrinsic centers for generating entangled photon pairs on a Si based device.

  8. A validity generalization procedure to test relations between intrinsic and extrinsic motivation and influence tactics.

    Science.gov (United States)

    Barbuto, John E; Moss, Jennifer A

    2006-08-01

    The relations of intrinsic and extrinsic motivation with use of consultative, legitimating, and pressure influence tactics were examined using validity generalization procedures. 5 to 7 field studies with cumulative samples exceeding 800 were used to test each relationship. Significance was found for relation between agents' intrinsic motivation and their use of consultative influence tactics and agents' extrinsic motivation and their use of legitimating influence tactics.

  9. Extrinsic Calibration for Vehicle-based Mobile Mapping System

    Directory of Open Access Journals (Sweden)

    SHI Limei

    2015-01-01

    Full Text Available Having the advantage of 360° imaging and rotation invariance, panoramic camera has gradually been used in mobile mapping systems(MMS. Calibration is an essential requirement to make sure that MMS can get high quality geo-information. This paper presents a way to address the extrinsic calibration for vehicle-based MMS composed of panoramic camera and Position and Orientation System (POS. Firstly, control points in the natural scene are set up, whose spatial coordinates are measured with high precision. Secondly, a panoramic spherical model is constructed and panoramic image can be projected to this model by means of spherical reverse transformation projection. Then, localize and select the control points in 3D spherical panoramic view but not in panoramic distorted image directly, the spherical coordinates of control points in panoramic image are gotten. After points correspondence is established, make use of direct geo-reference positioning equation and coordinate transformation, the translation and rotation parameters of panoramic camera relative to POS are computed. Experiments are conducted separately in space city calibration site located in Beijing and the Binhai New Area in Tianjin using our approach. Test results are listed as follows. When the GPS signal are of good quality, absolute positioning mean square error of a point is 10.3 cm in two-dimension plane and 16.5 cm in height direction; Otherwise, it is 35.4 cm in two-dimension plane and 54.8 cm in height direction. The max relative error of distance measurement is about 5 cm over a short distance (distance<3 km, which is not obviously affected by the GPS signal quality.

  10. Extrinsic information influences taste and flavor perception: a review from psychological and neuroimaging perspectives.

    Science.gov (United States)

    Okamoto, Masako; Dan, Ippeita

    2013-03-01

    The perception of taste and flavor can be greatly biased by extrinsic cues, or the information about a food that comes from outside of the food itself, such as package designs, brands, prices, and so on. In order to understand taste/flavor experiences in a broader context, it is necessary to consider factors other than the food/tastants themselves. This review aims to summarize some of the relevant findings from psychological and neuroimaging studies, focusing on depicting how extrinsic cues exert their effect on taste and flavor. Currently, the most frequently considered psychological mediator for the effects of extrinsic cues is expectation. Depending on the gap between expectation and taste/flavor experience, four major models predict outcomes of expectation effects: (1) assimilation, (2) generalized-negativity, (3) contrast, and (4) assimilation-contrast. Among them, the most influential is the assimilation model proposing that taste/flavor experiences are modified toward what one expects. Thus far, all the neuroimaging studies examining the influence of extrinsic cues have dealt with assimilation effects. They suggest that when extrinsic cues influence taste/flavor perception, cortical representations of taste/flavor are also modulated. Collectively neuroimaging findings partly answer questions arising from psychological aspects: the influence of extrinsic cues is not due to superficial response bias but to truly changed perception. These findings, albeit limited to assimilation effects, suggest that combined understanding from both psychological and neuroimaging studies would help deepen our understanding of the taste experience. Copyright © 2012. Published by Elsevier Ltd.

  11. Quantifying extrinsic noise in gene expression using the maximum entropy framework.

    Science.gov (United States)

    Dixit, Purushottam D

    2013-06-18

    We present a maximum entropy framework to separate intrinsic and extrinsic contributions to noisy gene expression solely from the profile of expression. We express the experimentally accessible probability distribution of the copy number of the gene product (mRNA or protein) by accounting for possible variations in extrinsic factors. The distribution of extrinsic factors is estimated using the maximum entropy principle. Our results show that extrinsic factors qualitatively and quantitatively affect the probability distribution of the gene product. We work out, in detail, the transcription of mRNA from a constitutively expressed promoter in Escherichia coli. We suggest that the variation in extrinsic factors may account for the observed wider-than-Poisson distribution of mRNA copy numbers. We successfully test our framework on a numerical simulation of a simple gene expression scheme that accounts for the variation in extrinsic factors. We also make falsifiable predictions, some of which are tested on previous experiments in E. coli whereas others need verification. Application of the presented framework to more complex situations is also discussed.

  12. The interplay of intrinsic and extrinsic bounded noises in biomolecular networks.

    Directory of Open Access Journals (Sweden)

    Giulio Caravagna

    Full Text Available After being considered as a nuisance to be filtered out, it became recently clear that biochemical noise plays a complex role, often fully functional, for a biomolecular network. The influence of intrinsic and extrinsic noises on biomolecular networks has intensively been investigated in last ten years, though contributions on the co-presence of both are sparse. Extrinsic noise is usually modeled as an unbounded white or colored gaussian stochastic process, even though realistic stochastic perturbations are clearly bounded. In this paper we consider Gillespie-like stochastic models of nonlinear networks, i.e. the intrinsic noise, where the model jump rates are affected by colored bounded extrinsic noises synthesized by a suitable biochemical state-dependent Langevin system. These systems are described by a master equation, and a simulation algorithm to analyze them is derived. This new modeling paradigm should enlarge the class of systems amenable at modeling. We investigated the influence of both amplitude and autocorrelation time of a extrinsic Sine-Wiener noise on: (i the Michaelis-Menten approximation of noisy enzymatic reactions, which we show to be applicable also in co-presence of both intrinsic and extrinsic noise, (ii a model of enzymatic futile cycle and (iii a genetic toggle switch. In (ii and (iii we show that the presence of a bounded extrinsic noise induces qualitative modifications in the probability densities of the involved chemicals, where new modes emerge, thus suggesting the possible functional role of bounded noises.

  13. Structural Coupling of Extrinsic Proteins with the Oxygen-Evolving Center in Photosystem II

    Directory of Open Access Journals (Sweden)

    Kentaro eIfuku

    2016-02-01

    Full Text Available Photosystem II (PSII, which catalyzes photosynthetic water oxidation, is composed of more than 20 subunits, including membrane-intrinsic and -extrinsic proteins. The PSII extrinsic proteins shield the catalytic Mn4CaO5 cluster from the outside bulk solution and enhance binding of inorganic cofactors, such as Ca2+ and Cl-, in the oxygen-evolving center (OEC of PSII. Among PSII extrinsic proteins, PsbO is commonly found in all oxygenic organisms, while PsbP and PsbQ are specific to higher plants and green algae, and PsbU, PsbV, CyanoQ, and CyanoP exist in cyanobacteria. In addition, red algae and diatoms have unique PSII extrinsic proteins, such as PsbQ’ and Psb31, suggesting functional divergence during evolution. Recent studies with reconstitution experiments combined with Fourier transform infrared spectroscopy have revealed how the individual PSII extrinsic proteins affect the structure and function of the OEC in different organisms. In this review, we summarize our recent results and discuss changes that have occurred in the structural coupling of extrinsic proteins with the OEC during evolutionary history.

  14. PRELIMINARY PROGRESS IN THE DEVELOPMENT OF DUCTILE-PHASE TOUGHENED TUNGSTEN FOR PLASMA-FACING MATERIALS: DUAL-PHASE FINITE ELEMENT DAMAGE MODELS

    Energy Technology Data Exchange (ETDEWEB)

    Henager, Charles H.; Nguyen, Ba Nghiep; Kurtz, Richard J.

    2016-09-30

    The objective of this study is to develop a finite element continuum damage model suitable for modeling deformation, cracking, and crack bridging for W-Cu, W-Ni-Fe, and other ductile phase toughened W-composites, or more generally, any multi-phase composite structure where two or more phases undergo cooperative deformation in a composite system.

  15. Strengthening and toughening of poly(L-lactide) composites by surface modified MgO whiskers

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Wei [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Luo, Binghong, E-mail: tluobh@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Qin, Xiaopeng; Li, Cairong [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Liu, Mingxian; Ding, Shan [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Zhou, Changren, E-mail: tcrz9@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China)

    2015-03-30

    Highlights: • The grafted PLLA chain on the surface of g-MgO whisker was ruled out by FTIR spectroscopy and TG/DTG analyses. • The excellent dispersion of g-MgO whiskers and the strong interfacial adhesion of g-MgO whiskers/PLLA composite were proved by FSEM. • Comparing to MgO particles and MgO whiskers, fibrous-like g-MgO whiskers are the most effective reinforcing and toughening fillers for PLLA. - Abstract: To improve both the strength and toughness of poly(L-lactide) (PLLA), fibrous-like MgO whiskers with diameters of 0.15–1 μm and lengths of 15–110 μm were prepared, and subsequently surface modified with L-lactide to obtain grafted MgO whiskers (g-MgO whiskers). The structures and properties of MgO whiskers and g-MgO whiskers were studied. Then, a series of MgO whiskers/PLLA and g-MgO whiskers/PLLA composites were prepared by solution casting method, for comparison, MgO particles/PLLA composite was prepared too. The resulting composites were evaluated in terms of hydrophilicity, crystallinity, dispersion of whiskers, interfacial adhesion and mechanical performance by means of polarized optical microscopy (POM), contact angle measurement, field emission scanning electron microscope (FSEM), transmission electron microscopy (TEM) and tensile testing. The results revealed that the crystallization rate and hydrophilicity of PLLA were improved by the introduction of MgO whiskers and g-MgO whiskers. The g-MgO whiskers can disperse more uniformly in and show stronger interfacial adhesion with the matrix than MgO whiskers as a result of the surface modification. Due to the bridge effect of the whiskers and the excellent interfacial adhesion between g-MgO whiskers and PLLA, g-MgO whiskers/PLLA composites exhibited remarkably higher strength, modulus and toughness compared to the pristine PLLA, MgO particles/PLLA and MgO whiskers/PLLA composites.

  16. PVC/特种CPE的共混增韧%Blended Toughening of PVC/Special CPE

    Institute of Scientific and Technical Information of China (English)

    杜壮; 徐超; 闫志佩; 赵季若; 冯莺

    2011-01-01

    The special chlorinated polyethylene was synthesized from high density polyethylene(HDPE) through solid phase method,in which a new kind chlorinated polyethylene(CPE) with special chlorine distribution was obtained by controlling temperature and time of the chlorinating reaction.The special chlorinated polyethylene(SCPE) can be used as a new modifier to toughen poly(vinyl chloride)(PVC).In this article,the mechanical property and microcosmic structure of SCPE and the blended system were studied.The results show that tensile strength of the blends increases 4% and notch impact strength of the blends increases 62.5% contrast to pure PVC.Results of DSC and 1H-NMR indicate that chain segments of different chlorine content exist in molecular chains of SCPE.The toughness of PVC can be modified by SCPE blended onto PVC while tensile strength of blends is improved.The analysis of morphological structure shows that the sufficient amalgamation between PVC phase and SCPE phase is excellent to improve mechanical property of the blends.%采用固相法对高密度聚乙烯(HDPE)进行氯化,得到分子链上具有特殊氯分布的特种氯化聚乙烯(CPE)(SCPE),其可以作为增韧剂对聚氯乙烯(PVC)增韧。结果表明,在SCPE含量为5份时,PVC/SCPE共混物的拉伸强度相对于PVC没有降低,反而提高了4%左右;缺口冲击强度提高了62.5%(13 kJ/m2)。差示扫描量热(DSC)和核磁共振(1H-NMR)的结果表明,SCPE分子链上特殊的氯嵌段结构对材料的性能至关重要。材料断面扫描电镜(SEM)分析表明PVC相与SCPE相的充分融合是力学性能优异的原因之一。

  17. In-situ fabricated TiB2 particle-whisker synergistically toughened Ti(C, N)-based ceramic cutting tool material

    Science.gov (United States)

    Liu, Hanlian; Shi, Qiang; Huang, Chuanzhen; Zou, Bin; Xu, Liang; Wang, Jun

    2015-03-01

    The mechanical properties of ceramic cutting tool materials can be modified by introducing proper content of nanoparticles or whiskers. However, the process of adding whiskers or nanoparticles has the disadvantages of high cost and health hazard as well as the agglomeration; although a new in-situ two-step sintering process can solve the above problems to some extent, yet the problems of low conversion ratio of the raw materials and the abnormal grain growth exist in this process. In this paper, an in-situ one-step synthesis technology is proposed, which means the growth of whiskers or nanoparticles and the sintering of the compact can be accomplished by one time in furnace. A kind of Ti(C, N)-based ceramic cutting tool material synergistically toughened by TiB2 particles and whiskers is fabricated with this new process. The phase compositions, relationships between microstructure and mechanical properties as well as the toughening mechanisms are analyzed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composite which is sintered under a pressure of 32 MPa at a temperature of 1700°C in vacuum holding for 60 min can get the optimal mechanical properties. Its flexural strength, fracture toughness and Vickers hardness are 540 MPa, 7.81 MPa · m1/2 and 20.42 GPa, respectively. The composite has relatively high density, and the in-situ synthesized TiB2 whiskers have good surface integrity, which is beneficial for the improvement of the fracture toughness. It is concluded that the main toughening mechanisms of the present composite are whiskers pulling-out and crack deflection induced by whiskers, crack bridging by whiskers/particles and multi-scale particles synergistically toughening. This study proposes an in-situ one-step synthesis technology which can be well used for fabricating particles and whiskers synergistically toughened ceramic tool materials.

  18. In-situ Fabricated TiB2 Particle-whisker Synergistically Toughened Ti(C, N)-based Ceramic Cutting Tool Material

    Institute of Scientific and Technical Information of China (English)

    LIU Hanlian; SHI Qiang; HUANG Chuanzhen; ZOU Bin; XU Liang; WANG Jun

    2015-01-01

    The mechanical properties of ceramic cutting tool materials can be modified by introducing proper content of nanoparticles or whiskers. However, the process of adding whiskers or nanoparticles has the disadvantages of high cost and health hazard as well as the agglomeration;although a new in-situ two-step sintering process can solve the above problems to some extent, yet the problems of low conversion ratio of the raw materials and the abnormal grain growth exist in this process. In this paper, an in-situ one-step synthesis technology is proposed, which means the growth of whiskers or nanoparticles and the sintering of the compact can be accomplished by one time in furnace. A kind of Ti(C, N)-based ceramic cutting tool material synergistically toughened by TiB2 particles and whiskers is fabricated with this new process. The phase compositions, relationships between microstructure and mechanical properties as well as the toughening mechanisms are analyzed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composite which is sintered under a pressure of 32 MPa at a temperature of 1700℃ in vacuum holding for 60 min can get the optimal mechanical properties. Its flexural strength, fracture toughness and Vickers hardness are 540 MPa, 7.81 MPa•m1/2 and 20.42 GPa, respectively. The composite has relatively high density, and the in-situ synthesized TiB2 whiskers have good surface integrity, which is beneficial for the improvement of the fracture toughness. It is concluded that the main toughening mechanisms of the present composite are whiskers pulling-out and crack deflection induced by whiskers, crack bridging by whiskers/particles and multi-scale particles synergistically toughening. This study proposes an in-situ one-step synthesis technology which can be well used for fabricating particles and whiskers synergistically toughened ceramic tool materials.

  19. Bimanual motor coordination controlled by cooperative interactions in intrinsic and extrinsic coordinates.

    Science.gov (United States)

    Sakurada, Takeshi; Ito, Koji; Gomi, Hiroaki

    2016-01-01

    Although strong motor coordination in intrinsic muscle coordinates has frequently been reported for bimanual movements, coordination in extrinsic visual coordinates is also crucial in various bimanual tasks. To explore the bimanual coordination mechanisms in terms of the frame of reference, here we characterized implicit bilateral interactions in visuomotor tasks. Visual perturbations (finger-cursor gain change) were applied while participants performed a rhythmic tracking task with both index fingers under an in-phase or anti-phase relationship in extrinsic coordinates. When they corrected the right finger's amplitude, the left finger's amplitude unintentionally also changed [motor interference (MI)], despite the instruction to keep its amplitude constant. Notably, we observed two specificities: one was large MI and low relative-phase variability (PV) under the intrinsic in-phase condition, and the other was large MI and high PV under the extrinsic in-phase condition. Additionally, using a multiple-interaction model, we successfully decomposed MI into intrinsic components caused by motor correction and extrinsic components caused by visual-cursor mismatch of the right finger's movements. This analysis revealed that the central nervous system facilitates MI by combining intrinsic and extrinsic components in the condition with in-phases in both intrinsic and extrinsic coordinates, and that under-additivity of the effects is explained by the brain's preference for the intrinsic interaction over extrinsic interaction. In contrast, the PV was significantly correlated with the intrinsic component, suggesting that the intrinsic interaction dominantly contributed to bimanual movement stabilization. The inconsistent features of MI and PV suggest that the central nervous system regulates multiple levels of bilateral interactions for various bimanual tasks.

  20. Swine leukocyte antigen class II genes (SLA-DRA, SLA-DRB1, SLA-DQA, SLA-DQB1) polymorphism and genotyping in Guizhou minipigs.

    Science.gov (United States)

    Liu, Z Z; Xia, J H; Xin, L L; Wang, Z G; Qian, L; Wu, S G; Yang, S L; Li, K

    2015-11-30

    The swine leukocyte antigen (SLA) complex harbors highly polymorphic gene clusters encoding glycoproteins that are involved in responses to vaccines, infectious disease, and production performance. Pigs with well-defined SLA class II genes are useful for the study of disease, immunology, and vaccines. In this study, we analyzed four SLA class II genes (SLA-DRA, SLA-DRB1, SLA-DQA, SLA-DQB1) in 22 founder Guizhou minipigs using a sequence-based typing method. Twelve alleles were detected, compared with the SLA class II allele sequences in the GenBank, and one of twelve alleles was found to be novel in Guizhou minipigs. There are four SLA II haplotypes, and one of them has been previously reported in Meishan pigs. Furthermore, based on sequence information of these alleles, we developed a simple SLA typing method implemented to SLA-typing for unknown offspring of Guizhou minipigs, relying on designed twelve sequence specific primers that could discriminate between each other. According to the combination of sequence-based typing and PCR-SSP, we were able to rapidly check SLA typing of Guizhou breeding stock and identified four SLA haplotypes in the herd. Therefore, SLA-defined Guizhou minipigs will be useful as animal models for xenotransplantation and immunological research.

  1. Predictors of employment in schizophrenia: The importance of intrinsic and extrinsic motivation.

    Science.gov (United States)

    Reddy, L Felice; Llerena, Katiah; Kern, Robert S

    2016-10-01

    Unemployment is a primary functional deficit for the majority of adults with schizophrenia. Research indicates that over two-thirds of adults living in the community with schizophrenia are unemployed. Despite effective programs to assist with job identification and placement, the ability to attain and maintain employment remains a pressing concern. A contributing factor that may be relevant but has received little attention in the work rehabilitation literature is motivation. People with schizophrenia show marked deficits in both intrinsic and extrinsic motivation but these deficits have not been directly examined in relation to work outcomes. The present study sought to examine the relationship between intrinsic and extrinsic motivation and work outcome among a sample of 65 adults with schizophrenia enrolled in a supported employment program. One-third of the participants in the study obtained work. Intrinsic motivation related to valuing and feeling useful in a work role significantly predicted who would obtain employment. Extrinsic motivation related to gaining rewards and avoiding obstacles showed a non-significant trend-level relationship such that workers had higher extrinsic motivation than nonworkers. These findings highlight the importance of considering both intrinsic and extrinsic motivation in work-related interventions and supported employment for individuals with schizophrenia. The results are discussed in terms of clinical implications for improving rehabilitation and occupational outcomes in schizophrenia. Published by Elsevier B.V.

  2. Structure and properties of polyamide 6 toughened by MAH grafted EPDM%EPDM-g-MAH增韧PA 6

    Institute of Scientific and Technical Information of China (English)

    周燕; 尹波; 李澜鹏; 杨鸣波

    2012-01-01

    制备了三种不同黏度的马来酸酐接枝三元乙丙橡胶(EPDM-g-MAH),将其用于增韧聚酰胺(PA)6.通过傅里叶变换红外光谱、扫描电子显微镜、差示扫描量热法、力学性能测试等表征了三元乙丙橡胶(EPDM)对增韧PA 6体系结构与性能的影响.结果表明:EPDM-g-MAH改善了PA 6与EPDM的相容性,用黏度适中的EPDM得到的EPDM-g-MAH与PA 6(质量比为85∶15)共混,分散相尺寸较小且分散均匀,共混体系的力学性能得到提高,特别是Izod缺口冲击强度几乎为PA 6的10倍.%The authors prepared three kinds of maleic anhydride (MAH) grafted ethylene-propylene-diene monomer (EPDM) with different viscosity (EPDM-g-MAH) and used them for toughening polyamide (PA) 6. The influences of the EPDM on the structure and properties of the toughened PA 6 system were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and mechanical properties tests. The results show that EPDM-g-MAH improves compatibility between EPDM and PA 6 matrix. The blend of EPDM-g-MAH containing EPDM with suitable viscosity and PA 6 has dispersed phase with smaller size and even distribution when the mass ratio of the former to the latter is 15 : 85. The blend possesses the improved mechanical properties; especially its notched Izod impact strength is almost 9 times higher than that of pure PA 6.

  3. In vitro ageing and wear behaviour of ceria stabilized zirconia toughened alumina (CSZ-TA) bio-ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Ajoy Kumar; Jena, Usha Rani; Biswas, Koushik, E-mail: k_biswas@metal.iitkgp.ernet.in

    2014-08-01

    15–25 wt% zirconia (stabilized with 14 mol% ceria) toughened alumina was synthesized by co-precipitation technique. The synthesized powders were calcined at different temperatures, compacted and conventionally sintered following two steps sintering process. Uniformly distributed submicron sized grains with Vickers' hardness value up to 1730±6HV20 were achieved after conventional sintering. In order to assess the ageing behaviour, samples were hydrothermally treated (in vitro) at 134 °C under 0.2 MPa in presence of simulated body fluid. Rietveld refinement of the X-ray diffraction patterns was carried out to estimate the phase content after calcination, sintering and after different stages of hydrothermal treatment. No significant phase change (only ∼3%) was observed even after 100 h of hydrothermal treatment. Very few bulged grains (resulted from the tetragonal to monoclinic phase transformation) on the surface and slight decrease in hardness value were observed after hydrothermal treatment. Fretting wear in dry condition was carried out taking ball on flat geometry for 10{sup 5} cycles at different loads before and after hydrothermal treatment. Wear volumes were directly estimated from the surface scanning of the wear scar using profilometer. Transition of wear and its related mechanisms at different loads along with the effect of ageing on wear were discussed. - Highlights: • Ceria stabilized zirconia toughened alumina was developed. • Ageing behaviour of developed materials was studied through hydrothermal treatment. • Phase transformation during ageing was characterized through Rietveld refinement. • Only 3% phase transformation was observed even after 100 h hydrothermal treatment. • Fretting wear volume before band after hydrothermal treatment were estimated.

  4. Extrinsic Contribution and Instability Properties in Lead-Based and Lead-Free Piezoceramics

    Directory of Open Access Journals (Sweden)

    José Eduardo García

    2015-11-01

    Full Text Available Piezoceramic materials generally exhibit a notable instability of their functional properties when they work under real external conditions. This undesirable effect, known as nonlinear behavior, is mostly associated with the extrinsic contribution to material response. In this article, the role of the ferroelectric domain walls’ motion in the nonlinear response in the most workable lead-based and lead-free piezoceramics is reviewed. Initially, the extrinsic origin of the nonlinear response is discussed in terms of the temperature dependence of material response. The influence of the crystallographic phase and of the phase boundaries on the material response are then reviewed. Subsequently, the impact of the defects created by doping in order to control the extrinsic contribution is discussed as a way of tuning material properties. Finally, some aspects related to the grain-size effect on the nonlinear response of piezoceramics are surveyed.

  5. Intrinsic and extrinsic mechanical properties related to the differentiation of mesenchymal stem cells.

    Science.gov (United States)

    Lee, Jin-Ho; Park, Hun-Kuk; Kim, Kyung Sook

    2016-05-06

    Diverse intrinsic and extrinsic mechanical factors have a strong influence on the regulation of stem cell fate. In this work, we examined recent literature on the effects of mechanical environments on stem cells, especially on differentiation of mesenchymal stem cells (MSCs). We provide a brief review of intrinsic mechanical properties of single MSC and examined the correlation between the intrinsic mechanical property of MSC and the differentiation ability. The effects of extrinsic mechanical factors relevant to the differentiation of MSCs were considered separately. The effect of nanostructure and elasticity of the matrix on the differentiation of MSCs were summarized. Finally, we consider how the extrinsic mechanical properties transfer to MSCs and then how the effects on the intrinsic mechanical properties affect stem cell differentiation.

  6. The Path Taken: Consequences of Attaining Intrinsic and Extrinsic Aspirations in Post-College Life.

    Science.gov (United States)

    Niemiec, Christopher P; Ryan, Richard M; Deci, Edward L

    2009-06-01

    Life goals, or aspirations, organize and direct behavior over extended periods of time. The present study, guided by self-determination theory, examined the consequences of pursuing and attaining aspirations over a one-year period in a post-college sample. Results indicated that placing importance on either intrinsic or extrinsic aspirations related positively to attainment of those goals. Yet, whereas attainment of intrinsic aspirations related positively to psychological health, attainment of extrinsic aspirations did not; indeed, attainment of extrinsic aspirations related positively to indicators of ill-being. Also as predicted, the association between change in attainment of intrinsic aspirations and change in psychological health was mediated by change in the satisfaction of the basic psychological needs for autonomy, competence, and relatedness. Discussion focuses on the idea that not all goal attainment is beneficial; rather, attainment of aspirations with different contents relates differentially to psychological health.

  7. Dissipationless spin-Hall current contribution in the extrinsic spin-Hall effect

    Institute of Scientific and Technical Information of China (English)

    Yan Yu-Zhen; Li Hui-Wu; Hu Liang-Bin

    2009-01-01

    This paper shows that a substantial amount of dissipationless spin-Hall current contribution may exist in the extrinsic spin-Hall effect, which originates from the spin-orbit coupling induced by the applied external electric field itself that drives the extrinsic spin-Hall effect in a nonmagnetic semiconductor (or metal). By assuming that the impurity density is in a moderate range such that the total scattering potential due to all randomly distributed impurities is a smooth function of the space coordinate, it is shown that this dissipationless contribution shall be of the same orders of magnitude as the usual extrinsic contribution from spin-orbit dependent impurity scatterings (or may even be larger than the latter one). The theoretical results obtained are in good agreement with recent relevant experimental results.

  8. The relationship between extrinsic motivation, job satisfaction and life satisfaction amongst employees in a public organisation

    Directory of Open Access Journals (Sweden)

    Chengedzai Mafini

    2014-02-01

    Full Text Available Orientation: There is much research on extrinsic motivation, job satisfaction and life satisfaction in organisations. However, empirical evidence on how such factors affect employees in public organisations in developing countries is lacking.Research purpose: To examine the relationships between extrinsic motivation, job satisfaction and life satisfaction amongst employees in a public organisation.Motivation for the study: Labour strife is an endemic phenomenon in South Africa’s public sector as evidenced by the high incidences of industrial action and labour turnover. This study contributes to this subject by identifying the extrinsic factors that could be optimised with a view to enhancing job and life satisfaction amongst government employees.Research approach, design and method: The study used the quantitative research survey approach: a questionnaire was administered to 246 employees in a South African public organisation. Extrinsic motivation factors were identified using principal components analysis. Mean score ranking was used to compare the relative importance of all factors. The conceptual framework was tested using Spearman’s rank correlation analysis and linear regression analysis.Main findings: Statistically significant relationships were observed between job satisfaction and four extrinsic motivation factors: remuneration, quality of work life, supervision and teamwork. The relationship with promotion was insignificant, but a statistically significant relationship was established with life satisfaction.Practical/managerial implications: The findings may be used to implement strategies for enhancing employee performance and industrial relations within public organisations.Contribution/value-add: The study provides evidence of the interplay between extrinsic motivation, job satisfaction and life satisfaction for public servants in developing countries.

  9. Limitations of surface EMG signals of extrinsic muscles in predicting postures of human hand.

    Science.gov (United States)

    Vinjamuri, Ramana; Mao, Zhi-Hong; Sclabassi, Robert; Sun, Mingui

    2006-01-01

    This paper explores the limitations of sEMG (surface Electromyography) signals collected from the extrinsic muscles in the forearm in predicting the postures of human hand. Four subjects were asked to try ten extreme postures of hand which need high effort. Two of these four subjects were asked to try ten more normal postures which did not need effort During the experiments, muscle activity and static postures of the hand were measured. The data obtained were analyzed by principal component analysis. The results obtained revealed the limitations of sEMG signals of extrinsic muscles in reproducing the postures of the hand.

  10. Computer tomographic patterns in extrinsic allergic alveolitis - a comparison with conventional radiological findings

    Energy Technology Data Exchange (ETDEWEB)

    Hieckel, H.G.; Mueller, S.; Luening, M.

    1986-10-01

    Seventeen patients with extrinsic allergic alveolitis or bird-fancier's lung were examined by standard radiological techniques and classified after Hapke's classification. In addition, the patients were examined by CT. The CT patterns have been analysed and compared with standard radiological findings. The methodological advantages of CT are discussed. Radiological investigation is of limited value in the diagnosis of extrinsic allergic alveolitis. Conventional radiography remains the standard of initial X-ray examination. In early cases, however, CT may be a valuable addition within the diagnostic strategy of a diagnostic imaging department.

  11. Substance use by college students: the role of intrinsic versus extrinsic motivation for athletic involvement.

    Science.gov (United States)

    Rockafellow, Bradley D; Saules, Karen K

    2006-09-01

    Certain types of athletic involvement may confer risk for substance use by college students. This study investigated whether motivational factors play a role in the relationship between athletic involvement and substance use. Intercollegiate athletes (n=98) and exercisers (n=120) were surveyed about substance use and motivation for athletic involvement. Athletes and exercisers who were extrinsically motivated had significantly higher rates of alcohol use than their intrinsically motivated counterparts. Results suggest that college students who are extrinsically motivated for involvement in physical activity/athletics--particularly those involved in team sports--may be in need of targeted prevention efforts. ((c) 2006 APA, all rights reserved).

  12. Research on Detection of Toughened Glass by Interferometric Method%干涉法检测钢化玻璃的研究

    Institute of Scientific and Technical Information of China (English)

    刘旭东; 陈景玉; 史颜波; 刘会龙; 董渊

    2012-01-01

      This paper presents a method of measuring the deformation of toughened glass by Mach -Zednder interferometer.Based on the theory, it gives the relationship between fringes variation quantity and tempered glass deformation .This method can improve the accura-cy of detection of toughened glass , and at last, it gives the theoretical simulation results .%  提出马赫-泽德干涉仪测量钢化玻璃的形变,其理论给出了条纹变化量和钢化玻璃形变量之间的关系,此方法可以提高钢化玻璃的检测精度,并给出了理论的模拟结果。

  13. 环氧树脂增韧改性研究进展%Research progress in toughening modification of epoxy resin

    Institute of Scientific and Technical Information of China (English)

    任圆

    2011-01-01

    The toughening modification methods of epoxy resins by using interpenetrating polymer networks, liquid crystal polymer, core -shell structure polymer, block copolymer and flexible curing agent were introduced. The toughening mechanism of each method was analyzed . The research progress of the methods at home and abroad were reviewed.%介绍了几种增韧改性环氧树脂的方法,包括互穿网络增韧、液晶聚合物增韧、核壳结构增韧、嵌段共聚物增韧及柔性固化剂增韧,分析了其机理,综述了上述改性方法的国内外研究进展.

  14. Radiation preparation of nano-powdered styrene-butadiene rubber (SBR) and its toughening effect for polystyrene and high-impact polystyrene

    Science.gov (United States)

    Li, Daishuang; Xia, Haibing; Peng, Jing; Zhai, Maolin; Wei, Genshuan; Li, Jiuqiang; Qiao, Jinliang

    2007-11-01

    Nano-powdered styrene-butadiene rubber (NPSBR) was synthesized based on the styrene-butadiene rubber (SBR) latex via gamma radiation crosslinking followed by spray drying. Two functional monomers, 2-ethyl hexyl acrylate (2-EHA) and trimethylolpropane triacrylate (TMPTA) were used as crosslinking agents. It was found that both 2-EHA and TMPTA can improve the radiation crosslinking of SBR latex. Transmission electron microscope (TEM) and scanning electron microscope (SEM) revealed that the NPSBR has a particle size similar to that of SBR latex with a diameter of 100 nm due to the high degree of crosslinking of SBR. Mechanical testing results showed that NPSBR could toughen polystyrene (PS) and high-impact polystyrene (HIPS) effectively. In addition, NPSBR is more suitable to toughen HIPS than PS at low rubber content.

  15. Radiation preparation of nano-powdered styrene-butadiene rubber (SBR) and its toughening effect for polystyrene and high-impact polystyrene

    Energy Technology Data Exchange (ETDEWEB)

    Li Daishuang; Xia Haibing [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Peng Jing [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)], E-mail: jpeng@pku.edu.cn; Zhai Maolin; Wei Genshuan; Li Jiuqiang [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Qiao Jinliang [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); SINOPEC, Beijing Research Institute of Chemical Industry, Beijing 100013 (China)

    2007-11-15

    Nano-powdered styrene-butadiene rubber (NPSBR) was synthesized based on the styrene-butadiene rubber (SBR) latex via gamma radiation crosslinking followed by spray drying. Two functional monomers, 2-ethyl hexyl acrylate (2-EHA) and trimethylolpropane triacrylate (TMPTA) were used as crosslinking agents. It was found that both 2-EHA and TMPTA can improve the radiation crosslinking of SBR latex. Transmission electron microscope (TEM) and scanning electron microscope (SEM) revealed that the NPSBR has a particle size similar to that of SBR latex with a diameter of 100 nm due to the high degree of crosslinking of SBR. Mechanical testing results showed that NPSBR could toughen polystyrene (PS) and high-impact polystyrene (HIPS) effectively. In addition, NPSBR is more suitable to toughen HIPS than PS at low rubber content.

  16. 聚合物基复合材料的增强增韧%Reinforcement and Toughening of Polymer Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    董金虎

    2012-01-01

    The methods and mechanisms in the reinforcement and toughening of polymers with small organic molecules, elastomers, rigid particles, fiber, and carbon nano-tubes were reviewed. Some representative polymer/reinforcer systems were introduced. The development of reinforcement and toughening of polymers was forecast.%介绍了聚合物基复合材料增强增韧的改性方法和机理,包括有机小分子、弹性体、刚性粒子、纤维以及碳纳米管增强增韧聚合物。并介绍了一些具有代表性的聚合物/增强增韧剂体系。并对聚合物基复合材料增强增韧的发展前景进行了展望。

  17. Modeling Ductile-Phase Toughened Tungsten for Plasma-Facing Materials: Progress in Damage Finite Element Analysis of the Tungsten-Copper Bend Bar Tests

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.

    2017-03-31

    The objective of this study is to investigate the deformation behavior of ductile phase toughened W-composites such as W-Cu and W-Ni-Fe by means of a multiscale finite element model that involves a microstructural dual-phase model where the constituent phases (i.e., W, Cu, Ni-Fe) are finely discretized and are described by a continuum damage model. Such a model is suitable for modeling deformation, cracking, and crack bridging for W-Cu, W-Ni-Fe, and other ductile phase toughened W-composites, or more generally, any multi-phase composite structure where two or more phases undergo cooperative deformation in a composite system. Our current work focuses on simulating the response and damage development of the W-Cu specimen subjected to three-point bending.

  18. Synergistically toughening effect of SiC whiskers and nanoparticles in Al2O3-based composite ceramic cutting tool material

    Science.gov (United States)

    Liu, Xuefei; Liu, Hanlian; Huang, Chuanzhen; Wang, Limei; Zou, Bin; Zhao, Bin

    2016-06-01

    In recent decades, many additives with different characteristics have been applied to strengthen and toughen Al2O3-based ceramic cutting tool materials. Among them, SiC whiskers and SiC nanoparticles showed excellent performance in improving the material properties. While no attempts have been made to add SiC whiskers and SiC nanoparticles together into the ceramic matrix and the synergistically toughening effects of them have not been studied. An Al2O3-SiCw-SiCnp advanced ceramic cutting tool material is fabricated by adding both one-dimensional SiC whiskers and zero-dimensional SiC nanoparticles into the Al2O3 matrix with an effective dispersing and mixing process. The composites with 25 vol% SiC whiskers and 25 vol% SiC nanoparticles alone are also investegated for comparison purposes. Results show that the Al2O3-SiCw-SiCnp composite with both 20 vol% SiC whiskers and 5 vol% SiC nanoparticles additives have much improved mechanical properties. The flexural strength of Al2O3-SiCw-SiCnp is 730±95 MPa and fracture toughness is 5.6±0.6 MPa·m1/2. The toughening and strengthening mechanisms of SiC whiskers and nanoparticles are studied when they are added either individually or in combination. It is indicated that when SiC whiskers and nanoparticles are added together, the grains are further refined and homogenized, so that the microstructure and fracture mode ratio is modified. The SiC nanoparticles are found helpful to enhance the toughening effects of the SiC whiskers. The proposed research helps to enrich the types of ceramic cutting tool and is benefit to expand the application range of ceramic cutting tool.

  19. Synergistically toughening effect of SiC whiskers and nanoparticles in Al2O3-based composite ceramic cutting tool material

    Science.gov (United States)

    Liu, Xuefei; Liu, Hanlian; Huang, Chuanzhen; Wang, Limei; Zou, Bin; Zhao, Bin

    2016-09-01

    In recent decades, many additives with different characteristics have been applied to strengthen and toughen Al2O3-based ceramic cutting tool materials. Among them, SiC whiskers and SiC nanoparticles showed excellent performance in improving the material properties. While no attempts have been made to add SiC whiskers and SiC nanoparticles together into the ceramic matrix and the synergistically toughening effects of them have not been studied. An Al2O3-SiCw-SiCnp advanced ceramic cutting tool material is fabricated by adding both one-dimensional SiC whiskers and zero-dimensional SiC nanoparticles into the Al2O3 matrix with an effective dispersing and mixing process. The composites with 25 vol% SiC whiskers and 25 vol% SiC nanoparticles alone are also investegated for comparison purposes. Results show that the Al2O3-SiCw-SiCnp composite with both 20 vol% SiC whiskers and 5 vol% SiC nanoparticles additives have much improved mechanical properties. The flexural strength of Al2O3-SiCw-SiCnp is 730±95 MPa and fracture toughness is 5.6±0.6 MPa·m1/2. The toughening and strengthening mechanisms of SiC whiskers and nanoparticles are studied when they are added either individually or in combination. It is indicated that when SiC whiskers and nanoparticles are added together, the grains are further refined and homogenized, so that the microstructure and fracture mode ratio is modified. The SiC nanoparticles are found helpful to enhance the toughening effects of the SiC whiskers. The proposed research helps to enrich the types of ceramic cutting tool and is benefit to expand the application range of ceramic cutting tool.

  20. Work Motivation and the Negative Effects of Extrinsic Rewards: A Reward With Implications for Theory and Practice

    Science.gov (United States)

    Notz, William W.

    1975-01-01

    Summarizes and discusses findings on two hypotheses predicting interaction between intrinsic and extrinsic motivation: extrinsic rewards are those which provide satisfaction independent of the actual activity itself and are controlled by someone other than the employee, whereas intrinsic rewards are those over which the employee has a high degree…

  1. NOISE-INDUCED TOUGHENING EFFECT IN WISTAR RATS: ENHANCED AUDITORY BRAINSTEM RESPONSES ARE RELATED TO CALRETININ AND NITRIC OXIDE SYNTHASE UPREGULATION.

    Directory of Open Access Journals (Sweden)

    Juan Carlos eAlvarado

    2016-03-01

    Full Text Available An appropriate conditioning noise exposure may reduce a subsequent noise-induced threshold shift. Although this toughening effect helps to protect the auditory system from a subsequent traumatic noise exposure, the mechanisms that regulate this protective process are not fully understood yet. Accordingly, the goal of the present study was to characterize physiological processes associated with ‘toughening’ and to determine their relationship to metabolic changes in the cochlea and cochlear nucleus (CN. Auditory brainstem responses (ABR were evaluated in Wistar rats before and after exposures to a sound conditioning protocol consisting of a broad-band white noise of 118 dB SPL for 1h every 72h, 4 times. After the last ABR evaluation, animals were perfused and their cochleae and brains removed and processed for the activity markers calretinin (CR and neuronal nitric oxide synthase (nNOS. Toughening was demonstrated by a progressively faster recovery of the threshold shift, as well as wave amplitudes and latencies over time. Immunostaining revealed an increase in CR and nNOS levels in the spiral ganglion, spiral ligament and CN in noise-conditioned rats. Overall, these results suggest that the protective mechanisms of the auditory toughening effect initiate in the cochlea and extend to the central auditory system. Such phenomenon might be in part related to an interplay between CR and nitric oxide signalling pathways, and involve an increased cytosolic calcium buffering capacity induced by the noise conditioning protocol.

  2. Extrinsic Motivation as Correlates of Work Attitude of the Nigerian Police Force: Implications for Counselling

    Science.gov (United States)

    Igun, Sylvester Nosakhare

    2008-01-01

    The study examined Extrinsic motivation as correlates of work attitude of the Nigeria Police Force and its implications for counselling. 300 Police personnel were selected by random sampling technique from six departments that make up police force Headquarters, Abuja. The personnel were selected from each department using simple sampling…

  3. Extrinsic functions of lectin domains in O-N-acetylgalactosamine glycan biosynthesis

    DEFF Research Database (Denmark)

    Lorenz, Virginia; Ditamo, Yanina; Cejas, Romina B;

    2016-01-01

    Glycan biosynthesis occurs mainly in Golgi. Molecular organization and functional regulation of this process are not well understood. We evaluated the extrinsic effect of lectin domains (β-trefoil fold) of polypeptide GalNAc-transferases (ppGalNAc-Ts) on catalytic activity of glycosyltransferases...

  4. Perceived Constraints on Recreational Sport Participation: Investigating Their Relationship with Intrinsic Motivation, Extrinsic Motivation and Amotivation.

    Science.gov (United States)

    Alexandris, Konstantinos; Tsorbatzoudis, Charalambos; Grouios, George

    2002-01-01

    Investigated the influence of constraint dimensions on intrinsic motivation, extrinsic motivation, and amotivation among Greek adults who reported participation in some type of sport and physical activity. Data from the Sport Motivation Scale and leisure constraints questionnaire revealed that intrapersonal constraints acted as de-motivating…

  5. Tangible and Intangible Rewards and Employee Creativity: The Mediating Role of Situational Extrinsic Motivation

    Science.gov (United States)

    Yoon, Hye Jung; Sung, Sun Young; Choi, Jin Nam; Lee, Kyungmook; Kim, Seongsu

    2015-01-01

    This study examined the effects of tangible and intangible forms of creativity-contingent rewards on employee creativity. Situation-specific intrinsic and extrinsic motivations were proposed as mediators of the reward-creativity link. Based on data collected from 271 employees and their supervisors, results revealed the following: (a) intangible…

  6. A Novel Extrinsic Fiber-Optic Fabry-Perot Strain Sensor System Based on Optical Amplification

    Institute of Scientific and Technical Information of China (English)

    Yun-Jiang Rao; Jian Jiang; Zheng-Lin Ran

    2003-01-01

    A novel extrinsic fiber-optic Fabry-Perot interferometric strain sensor system is demonstrated based on the simultaneous use of the amplified spontaneous emission and optical amplification. The improvement of 3~4 orders of magnitude in signal level can be achieved.

  7. A Quantitative Analysis of the Extrinsic and Intrinsic Turnover Factors of Relational Database Support Professionals

    Science.gov (United States)

    Takusi, Gabriel Samuto

    2010-01-01

    This quantitative analysis explored the intrinsic and extrinsic turnover factors of relational database support specialists. Two hundred and nine relational database support specialists were surveyed for this research. The research was conducted based on Hackman and Oldham's (1980) Job Diagnostic Survey. Regression analysis and a univariate ANOVA…

  8. The fragmented self : imbalance between intrinsic and extrinsic self-networks in psychotic disorders

    NARCIS (Netherlands)

    Ebisch, Sjoerd J. H.; Aleman, Andre

    2016-01-01

    Self-disturbances are among the core features of schizophrenia and related psychotic disorders. The basic structure of the self could depend on the balance between intrinsic and extrinsic self-processing. We discuss studies on self-related processing in psychotic disorders that provide converging ev

  9. A family with extrinsic allergic alveolitis caused by wild city pigeons: A case report

    NARCIS (Netherlands)

    G.J. du Marchie Sarvaas; P.J.F.M. Merkus (Peter); J.C. de Jongste (Johan)

    2000-01-01

    textabstractWe describe a family in which the mother died of unresolved lung disease and whose 5 children, some of whom had previous signs of asthma, were subsequently affected by extrinsic allergic alveolitis caused by contact with wild city pigeon antigens. The children received

  10. Intrinsic and Extrinsic Motivation: Evaluating Benefits and Drawbacks from College Instructors' Perspectives

    Science.gov (United States)

    Lei, Simon A.

    2010-01-01

    A growing body of literature has been examined and discussed the effects of intrinsic and extrinsic motivation on student learning at the college level. Intrinsically motivated individuals have been able to develop high regards for learning various types of course information without the inclusion of external rewards or reinforcements. In…

  11. Extrinsic Tooth Enamel Color Changes and Their Relationship with the Quality of Water Consumed

    Directory of Open Access Journals (Sweden)

    Maria da Luz Rosário de Sousa

    2012-10-01

    Full Text Available The quality of the consumed drinking water may affect oral health. For example, the presence of iron in drinking water can cause aesthetic problems related to changes in dental enamel color. This study assessed the prevalence of extrinsic enamel color changes and their relationship with the quality of the water in the town of Caapiranga/AM-Brazil. Three hundred and forty six residents of the urban area were examined, and they also answered a questionnaire on eating habits and self-perceived oral health. As the initial results indicated an insufficient number of observations for the application of variance analysis (one-way ANOVA, the Student t test was chosen to compare levels of iron content in the water coming from two sources. The change in tooth color had a prevalence of 5.78% (20 people. The majority of the population (n = 261, 75.43% consumed well water. Those who presented extrinsic stains were uncomfortable with the appearance of their teeth (15.09%. We conclude that while there is excess of iron in the water in this region of Brazil, no association between extrinsic stains on the enamel and the level of iron in the water was found. There was a low prevalence of extrinsic stains in Caaparinga, being found only in children and adolescents. In the present study, an association between the presence of stains and the consumption of açai was determined, and those who presented them felt uncomfortable about their aesthetics.

  12. Creep of current-driven domain-wall lines: intrinsic versus extrinsic pinning

    NARCIS (Netherlands)

    Duine, R.A.; de Morais Smith, C.

    2008-01-01

    We present a model for current-driven motion of a magnetic domain-wall line, in which the dynamics of the domain wall is equivalent to that of an overdamped vortex line in an anisotropic pinning potential. This potential has both extrinsic contributions due to, e.g., sample inhomogeneities, and an

  13. Profiles of Intrinsic and Extrinsic Motivations in Elementary School: A Longitudinal Analysis

    Science.gov (United States)

    Corpus, Jennifer Henderlong; Wormington, Stephanie V.

    2014-01-01

    The authors used a person-centered, longitudinal approach to identify and evaluate naturally occurring combinations of intrinsic and extrinsic motivations among 490 third- through fifth-grade students. Cluster analysis revealed 3 groups, characterized by high levels of both motivations ("high quantity"): high intrinsic motivation but low…

  14. Students' Extrinsic and Intrinsic Motivation Level and Its Relationship with Their Mathematics Achievement

    Science.gov (United States)

    Acar Güvendir, Meltem

    2016-01-01

    This study focused on the extrinsic and intrinsic motivation levels of eighth grade students and its relationship with their mathematical achievement. The participants of the study included 6,829 students who took TIMSS in 2011 and 239 mathematics teachers. The data obtained from the student and teacher questionnaires that are included in the…

  15. Intrinsic Motivation, Extrinsic Motivation, and Academic Achievement among Indian Adolescents in Canada and India

    Science.gov (United States)

    Areepattamannil, Shaljan; Freeman, John G.; Klinger, Don A.

    2011-01-01

    The purpose of the present study was to examine the relationships among intrinsic motivation, extrinsic motivation, and academic achievement for the Indian immigrant adolescents in Canada in comparison to their counterparts in India. Descriptive discriminant analysis indicated that the Indian immigrant adolescents in Canada had higher intrinsic…

  16. Intrinsic and Extrinsic Reading Motivation as Predictors of Reading Literacy: A Longitudinal Study

    Science.gov (United States)

    Becker, Michael; McElvany, Nele; Kortenbruck, Marthe

    2010-01-01

    The purpose in this study was to examine the longitudinal relationships of intrinsic and extrinsic motivation with reading literacy development. In particular, the authors (a) investigated reading amount as mediator between motivation and reading literacy and (b) probed for bidirectional relationships between reading motivation and reading…

  17. Hypoxia in human colorectal adenocarcinoma: comparison between extrinsic and potential intrinsic hypoxia markers.

    NARCIS (Netherlands)

    Goethals, L.; Debucquoy, A.; Perneel, C.; Geboes, K.; Ectors, N.; Schutter, H. De; Penninckx, F.; McBride, W.H.; Begg, A.C.; Haustermans, K.

    2006-01-01

    PURPOSE: To detect and quantify hypoxia in colorectal adenocarcinomas by use of pimonidazole and iododeoxyuridine (IdUrd) as extrinsic markers and carbonic anhydrase IX (CA IX), microvessel density (MVD), epidermal growth-factor receptor (EGFR), and vascular endothelial growth factor (VEGF) as intri

  18. Extrinsic and intrinsic drivers of corporate social performance: evidence from foreign and domestic firms in Mexico

    NARCIS (Netherlands)

    Muller, A.; Kolk, A.

    2010-01-01

    The literature on corporate social performance (CSP) is largely split between approaches that consider CSP to be extrinsically driven and those that consider it to be intrinsically driven. While the management literature has paid attention to drivers of both types, the relationship between the two

  19. A family with extrinsic allergic alveolitis caused by wild city pigeons: A case report

    NARCIS (Netherlands)

    G.J. du Marchie Sarvaas; P.J.F.M. Merkus (Peter); J.C. de Jongste (Johan)

    2000-01-01

    textabstractWe describe a family in which the mother died of unresolved lung disease and whose 5 children, some of whom had previous signs of asthma, were subsequently affected by extrinsic allergic alveolitis caused by contact with wild city pigeon antigens. The children received

  20. Blowing in the (social) wind: implications of extrinsic esteem contingencies for terror management and health.

    Science.gov (United States)

    Arndt, Jamie; Cox, Cathy R; Goldenberg, Jamie L; Vess, Matthew; Routledge, Clay; Cooper, Douglas P; Cohen, Florette

    2009-06-01

    In 4 studies, the role of extrinsic esteem contingencies in adjusting to shifting health-relevant standards when managing existential fears was examined. Study 1 demonstrated that after reminders of death, higher dispositional focus on extrinsic self-esteem contingencies predicted greater interest in tanning. Using a more domain-specific approach, Study 2 showed that, after being reminded of death, the more individuals smoke for social esteem reasons, the more compelling they find an antismoking commercial that exposes adverse social consequences of smoking. Study 3 explored how situational factors (i.e., priming a contingent relational schema) that implicate extrinsic contingencies facilitated the impact of shifting standard primes on tanning intentions after mortality salience. Finally, Study 4 found that mortality salience led to increased endorsement of exercise as a basis of self-worth when participants who derive self-esteem from extrinsic sources visualized someone who exercises. Together, these studies demonstrate that reminders of death interact with prevalent social standards to influence everyday health decisions.

  1. The fragmented self: imbalance between intrinsic and extrinsic self-networks in psychotic disorders.

    Science.gov (United States)

    Ebisch, Sjoerd J H; Aleman, André

    2016-08-01

    Self-disturbances are among the core features of schizophrenia and related psychotic disorders. The basic structure of the self could depend on the balance between intrinsic and extrinsic self-processing. We discuss studies on self-related processing in psychotic disorders that provide converging evidence for disrupted communication between neural networks subserving the so-called intrinsic self and extrinsic self. This disruption might be mainly caused by impaired integrity of key brain hubs. The intrinsic self has been associated with cortical midline structures involved in self-referential processing, autobiographical memory, and emotional evaluation. Additionally, we highlight central aspects of the extrinsic self in its interaction with the environment using sensorimotor networks, including self-experience in sensation and actions. A deficient relationship between these self-aspects because of disrupted between-network interactions offers a framework to explain core clinical features of psychotic disorders. In particular, we show how relative isolation and reduced modularity of networks subserving intrinsic and extrinsic self-processing might trigger the emergence of hallucinations and delusions, and why patients with psychosis typically have difficulties with self-other relationships and do not recognise mental problems.

  2. Comparing Intrinsic and Extrinsic Evaluation of MT Output in a Dialogue System.

    NARCIS (Netherlands)

    van der Sluis, Ielka; Luz, S.; Schneider, A.

    2010-01-01

    We present an exploratory study to assess machine translation output for application in a dialogue system using an intrinsic and an extrinsic evaluation method. For the intrinsic evaluation we developed an annotation scheme to determine the quality of the translated utterances in isolation. For the

  3. A Novel Extrinsic Fiber-Optic Fabry-Perot Strain Sensor System Based on Optical Amplification

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel extrinsic fiber-optic Fabry-Perot interferometric strain sensor system is demonstrated based on the simultaneous use of the amplified spontaneous emission and optical amplification. The improvement of 3~4 orders of magnitude in signal level can be achieved.

  4. The efficacy of two prototype chewing gums for the removal of extrinsic tooth stain

    NARCIS (Netherlands)

    Ozcan, M; Kulak, Y; Kazazoglu, E

    2003-01-01

    Aim: To compare the potential efficacy of two prototype chewing gums in extrinsic stain removal on natural teeth. Setting: Dental school clinics. Design: Double-blind, two groups, parallel design. Participants: 76 adult volunteers (32m, 44f, mean age: 20.6 years old). Methods: Oral hard and soft tis

  5. Further Examining the American Dream: Differential Correlates of Intrinsic and Extrinsic Goals.

    Science.gov (United States)

    Kasser, Tim; Ryan, Richard M.

    1996-01-01

    In a sample of adult subjects (Study One), the relative importance and efficacy of extrinsic aspirations for financial success, an appealing appearance, and social recognition were associated with lower vitality and self-actualization and more physical symptoms. Study Two replicated these findings in a sample of college students. (JPS)

  6. Intrinsic and Extrinsic Factors That Influence Black Males to Attend Institutions of Higher Education

    Science.gov (United States)

    Etheridge, Robert

    2013-01-01

    The purpose of this qualitative, narrative study was to explore the intrinsic and extrinsic factors that motivated Black males to attend institutions of higher education. The Self-determination theory and the Integrated Model for Educational Choice formed the theoretical framework for this study. Eight Black males who were between the ages of 18…

  7. Indirect Correspondence-Based Robust Extrinsic Calibration of LiDAR and Camera.

    Science.gov (United States)

    Sim, Sungdae; Sock, Juil; Kwak, Kiho

    2016-06-22

    LiDAR and cameras have been broadly utilized in computer vision and autonomous vehicle applications. However, in order to convert data between the local coordinate systems, we must estimate the rigid body transformation between the sensors. In this paper, we propose a robust extrinsic calibration algorithm that can be implemented easily and has small calibration error. The extrinsic calibration parameters are estimated by minimizing the distance between corresponding features projected onto the image plane. The features are edge and centerline features on a v-shaped calibration target. The proposed algorithm contributes two ways to improve the calibration accuracy. First, we use different weights to distance between a point and a line feature according to the correspondence accuracy of the features. Second, we apply a penalizing function to exclude the influence of outliers in the calibration datasets. Additionally, based on our robust calibration approach for a single LiDAR-camera pair, we introduce a joint calibration that estimates the extrinsic parameters of multiple sensors at once by minimizing one objective function with loop closing constraints. We conduct several experiments to evaluate the performance of our extrinsic calibration algorithm. The experimental results show that our calibration method has better performance than the other approaches.

  8. Intrinsic and Extrinsic Reading Motivation as Predictors of Reading Literacy: A Longitudinal Study

    Science.gov (United States)

    Becker, Michael; McElvany, Nele; Kortenbruck, Marthe

    2010-01-01

    The purpose in this study was to examine the longitudinal relationships of intrinsic and extrinsic motivation with reading literacy development. In particular, the authors (a) investigated reading amount as mediator between motivation and reading literacy and (b) probed for bidirectional relationships between reading motivation and reading…

  9. Profiles of Intrinsic and Extrinsic Motivations in Elementary School: A Longitudinal Analysis

    Science.gov (United States)

    Corpus, Jennifer Henderlong; Wormington, Stephanie V.

    2014-01-01

    The authors used a person-centered, longitudinal approach to identify and evaluate naturally occurring combinations of intrinsic and extrinsic motivations among 490 third- through fifth-grade students. Cluster analysis revealed 3 groups, characterized by high levels of both motivations ("high quantity"): high intrinsic motivation but low…

  10. The dark side of monetary incentive: how does extrinsic reward crowd out intrinsic motivation.

    Science.gov (United States)

    Ma, Qingguo; Jin, Jia; Meng, Liang; Shen, Qiang

    2014-02-12

    It was widely believed that incentives could effectively enhance the motivation of both students and employees. However, psychologists reported that extrinsic reward actually could undermine individuals' intrinsic motivation to a given interesting task, which challenged viewpoints from traditional incentive theories. Numerous studies have been carried out to test and explain the undermining effect; however, the neural basis of this effect is still elusive. Here, we carried out an electrophysiological study with a simple but interesting stopwatch task to explore to what extent the performance-based monetary reward undermines individuals' intrinsic motivation toward the task. The electrophysiological data showed that the differentiated feedback-related negativity amplitude toward intrinsic success failure divergence was prominently reduced once the extrinsic reward was imposed beforehand. However, such a difference was not observed in the control group, in which no extrinsic reward was provided throughout the experiment. Furthermore, such a pattern was not observed for P300 amplitude. Therefore, the current results indicate that extrinsic reward demotivates the intrinsic response of individuals toward success-failure outcome, which was reflected in the corresponding reduced motivational-related differentiated feedback-related negativity, but not in amplitude of P300.

  11. Intrinsic Motivation, Extrinsic Motivation, and Academic Achievement among Indian Adolescents in Canada and India

    Science.gov (United States)

    Areepattamannil, Shaljan; Freeman, John G.; Klinger, Don A.

    2011-01-01

    The purpose of the present study was to examine the relationships among intrinsic motivation, extrinsic motivation, and academic achievement for the Indian immigrant adolescents in Canada in comparison to their counterparts in India. Descriptive discriminant analysis indicated that the Indian immigrant adolescents in Canada had higher intrinsic…

  12. Students' Extrinsic and Intrinsic Motivation Level and Its Relationship with Their Mathematics Achievement

    Science.gov (United States)

    Acar Güvendir, Meltem

    2016-01-01

    This study focused on the extrinsic and intrinsic motivation levels of eighth grade students and its relationship with their mathematical achievement. The participants of the study included 6,829 students who took TIMSS in 2011 and 239 mathematics teachers. The data obtained from the student and teacher questionnaires that are included in the…

  13. Promoting Intrinsic and Extrinsic Motivation among Chemistry Students Using Computer-Assisted Instruction

    Science.gov (United States)

    Gambari, Isiaka A.; Gbodi, Bimpe E.; Olakanmi, Eyitao U.; Abalaka, Eneojo N.

    2016-01-01

    The role of computer-assisted instruction in promoting intrinsic and extrinsic motivation among Nigerian secondary school chemistry students was investigated in this study. The study employed two modes of computer-assisted instruction (computer simulation instruction and computer tutorial instructional packages) and two levels of gender (male and…

  14. Intrinsic and Extrinsic Motivation: Evaluating Benefits and Drawbacks from College Instructors' Perspectives

    Science.gov (United States)

    Lei, Simon A.

    2010-01-01

    A growing body of literature has been examined and discussed the effects of intrinsic and extrinsic motivation on student learning at the college level. Intrinsically motivated individuals have been able to develop high regards for learning various types of course information without the inclusion of external rewards or reinforcements. In…

  15. Effects of Success/Failure and Extrinsic Rewards on Intrinsic Motivation Using a Competitive Motor Task.

    Science.gov (United States)

    McCaughan, Lindsay R.; McKinlay, Sue

    1981-01-01

    Female high school students participated in a motor task to assess the effects of success/failure feedback and extrinsic rewards on intrinsic motivation. It was found that a significant change in intrinsic motivation was due to the effects of success/failure feedback, but not to the effect of a tangible reward. (Authors/FG)

  16. Interactive Impact of Intrinsic Motivators and Extrinsic Rewards on Behavior and Motivation Outcomes

    Science.gov (United States)

    Xiang, Ping; Bruene, April; Chen, Ang

    2005-01-01

    In this study we examined the interrelationship among extrinsic rewards and achievement goals (including a work-avoidance goal), competence beliefs, and task values associated with health-enhancing running tasks over a school year. A group of elementary school students (n = 119) from a program that promoted running for running's sake and another…

  17. Interactive Impact of Intrinsic Motivators and Extrinsic Rewards on Behavior and Motivation Outcomes

    Science.gov (United States)

    Xiang, Ping; Bruene, April; Chen, Ang

    2005-01-01

    In this study we examined the interrelationship among extrinsic rewards and achievement goals (including a work-avoidance goal), competence beliefs, and task values associated with health-enhancing running tasks over a school year. A group of elementary school students (n = 119) from a program that promoted running for running's sake and another…

  18. Teacher Rewards: Going beyond the Stickers--Moving beyond Extrinsic Motivation

    Science.gov (United States)

    Taylor, Cheryl; McNaney-Funk, Claire; Jardine, Don; Lehman, Geannette; Fok-Chan, Evelyn

    2014-01-01

    Studies have shown that teachers appreciate intrinsic rewards, such as student achievement, positive relationships with students, self-growth, and mastery of professional skills, far greater than extrinsic motivators, like holidays and salary (Plihal, 1981; Plihal, 1982; Ashiedu & Scott-Ladd, 2012; Baleghizadeh & Gordani, 2012). This paper…

  19. Increasing Elementary and High School Student Motivation through the Use of Extrinsic and Intrinsic Rewards

    Science.gov (United States)

    Haywood, Joey; Kuespert, Sarah; Madecky, Dani; Nor, Abbey

    2008-01-01

    This action research project report examined strategies to motivate students from extrinsically rewarding behaviors to intrinsically motivating behaviors. The action research was conducted in two different schools by four different teacher researchers within the same district. Three teachers in an elementary building (Site A) and one teacher in a…

  20. The role of extrinsic rewards and cue-intention association in prospective memory in young children

    NARCIS (Netherlands)

    Sheppard, D.P.; Kretschmer, A.; Knispel, E.; Vollert, B.; Altgassen, A.M.

    2015-01-01

    The current study examined, for the first time, the effect of cue-intention association, as well as the effects of promised extrinsic rewards, on prospective memory in young children, aged 5-years-old (n = 39) and 7-years-old (n = 40). Children were asked to name pictures for a toy mole, whilst also

  1. Effects of Success/Failure and Extrinsic Rewards on Intrinsic Motivation Using a Competitive Motor Task.

    Science.gov (United States)

    McCaughan, Lindsay R.; McKinlay, Sue

    1981-01-01

    Female high school students participated in a motor task to assess the effects of success/failure feedback and extrinsic rewards on intrinsic motivation. It was found that a significant change in intrinsic motivation was due to the effects of success/failure feedback, but not to the effect of a tangible reward. (Authors/FG)

  2. Intrinsic Motivation and Extrinsic Rewards: A Commentary on Cameron and Pierce's Meta-Analysis.

    Science.gov (United States)

    Lepper, Mark R.; And Others

    1996-01-01

    Provides a critical analysis of the meta-analysis of J. Cameron and W. D. Pierce (1994) of the experimental literature on the effects of extrinsic rewards on intrinsic motivation. Their overly simplistic conclusion has little theoretical or practical value and results from misuse of meta-analytic procedures. (SLD)

  3. Tangible and Intangible Rewards and Employee Creativity: The Mediating Role of Situational Extrinsic Motivation

    Science.gov (United States)

    Yoon, Hye Jung; Sung, Sun Young; Choi, Jin Nam; Lee, Kyungmook; Kim, Seongsu

    2015-01-01

    This study examined the effects of tangible and intangible forms of creativity-contingent rewards on employee creativity. Situation-specific intrinsic and extrinsic motivations were proposed as mediators of the reward-creativity link. Based on data collected from 271 employees and their supervisors, results revealed the following: (a) intangible…

  4. The fragmented self : imbalance between intrinsic and extrinsic self-networks in psychotic disorders

    NARCIS (Netherlands)

    Ebisch, Sjoerd J. H.; Aleman, Andre

    2016-01-01

    Self-disturbances are among the core features of schizophrenia and related psychotic disorders. The basic structure of the self could depend on the balance between intrinsic and extrinsic self-processing. We discuss studies on self-related processing in psychotic disorders that provide converging ev

  5. An Analysis of Intrinsic and Extrinsic Hand Muscle EMG for Improved Pattern Recognition Control.

    Science.gov (United States)

    Adewuyi, Adenike A; Hargrove, Levi J; Kuiken, Todd A

    2016-04-01

    Pattern recognition control combined with surface electromyography (EMG) from the extrinsic hand muscles has shown great promise for control of multiple prosthetic functions for transradial amputees. There is, however, a need to adapt this control method when implemented for partial-hand amputees, who possess both a functional wrist and information-rich residual intrinsic hand muscles. We demonstrate that combining EMG data from both intrinsic and extrinsic hand muscles to classify hand grasps and finger motions allows up to 19 classes of hand grasps and individual finger motions to be decoded, with an accuracy of 96% for non-amputees and 85% for partial-hand amputees. We evaluated real-time pattern recognition control of three hand motions in seven different wrist positions. We found that a system trained with both intrinsic and extrinsic muscle EMG data, collected while statically and dynamically varying wrist position increased completion rates from 73% to 96% for partial-hand amputees and from 88% to 100% for non-amputees when compared to a system trained with only extrinsic muscle EMG data collected in a neutral wrist position. Our study shows that incorporating intrinsic muscle EMG data and wrist motion can significantly improve the robustness of pattern recognition control for application to partial-hand prosthetic control.

  6. Flavor Profile of Chinese Liquor Is Altered by Interactions of Intrinsic and Extrinsic Microbes.

    Science.gov (United States)

    Wu, Qun; Kong, Yu; Xu, Yan

    2015-10-16

    The flavor profile of Chinese liquor is the result of the metabolic activity of its microbial community. Given the importance of the microbial interaction, a novel way to control the liquor's flavor is by regulating the composition of the community. In this study, we efficiently improved the liquor's flavor by perturbing the intrinsic microbial metabolism with extrinsic microbes. We first constructed a basic microbial group (intrinsic) containing Saccharomyces cerevisiae, Wickerhamomyces anomalus, and Issatchenkia orientalis and added special flavor producers (extrinsic), Saccharomyces uvarum and Saccharomyces servazzii, to this intrinsic group. Upon the addition of the extrinsic microbes, the maximum specific growth rates of S. cerevisiae and I. orientalis increased from 6.19 to 43.28/day and from 1.15 to 14.32/day, respectively, but that of W. anomalus changed from 1.00 to 0.96/day. In addition, most volatile compounds known to be produced by the extrinsic strains were not produced. However, more esters, alcohols, and acids were produced by S. cerevisiae and I. orientalis. Six compounds were significantly different by random forest analysis after perturbation. Among them, increases in ethyl hexanoate, isobutanol, and 3-methylbutyric acid were correlated with S. cerevisiae and I. orientalis, and a decrease in geranyl acetone was correlated with W. anomalus. Variations in ethyl acetate and 2-phenylethanol might be due to the varied activity of W. anomalus and S. cerevisiae. This work showed the effect of the interaction between the intrinsic and extrinsic microbes on liquor flavor, which would be beneficial for improving the quality of Chinese liquor. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  7. Research on DRA outdoor buried test loop and transient model%减阻剂室外埋地评价环道及瞬态模型

    Institute of Scientific and Technical Information of China (English)

    黄启玉; 王培伟; 刘丽飞

    2013-01-01

    The evaluation experiment of DRA is mainly conducted in indoor test loop.Indoor test loop has a small diameter and length,the flowrate of the oil in indoor test loops differs considerably from that in actual pipelines.In view of these shortages of indoor test loop,an outdoor test loop of 300 m-long with a diameter of 159 mm is designed and built,in which the flowrate of oil is more close to that in actual pipelines.Using high-pressure nitrogen as source power,the unit has high accuracy pressure transducers and high frequency pressure transducers along the test section,ultrasonic flow meter at the outlet of the test section,and high pressure tank and normal pressure tank.Because of the continuous variation in pressure,a transient model of the experiment process is established to calculate the change in flowrate and pressure,the range of Reynolds number as well as the experimental duration under different oil viscosity and various initial pressures.%针对减阻剂室内评价环道存在的问题,设计安装了管径159mm、长300m的室外埋地评价环道,其管径、长度、油品流速更接近于实际管道.该装置采用高压氮气作为动力源,测试段沿线布设高精度压力传感器和高频压力传感器,测试段出口设有超声波流量计,同时安装有耐压罐和常压罐.由于在环道评价试验中装置的压力不断变化,因此建立了试验过程氮气管路、油品管路、氮气罐、耐压罐的瞬态模型,使用VB语言编制了计算程序,用以计算不同粘度和初始压力下的油品流速和压力变化,雷诺数范围和试验时间,判断试验条件的可行性.

  8. Mechanical properties of epoxidized natural rubber toughen ed poly(vinyl chloride)%环氧化天然橡胶增韧聚氯乙烯力学性能研究

    Institute of Scientific and Technical Information of China (English)

    王桂强; 贺继东; 赵强; 易芬莲; 李思东

    2001-01-01

    The mechanical properties of epoxidized natural rubber(EN R-50)toughened poly(vinyl chloried) (PVC) were studied.The effects of plasticize r DOP and antio xidant 4010 on PVC/ENR-50 toughened system were researched.The results showed th at ENR had good toughening effect on PVC,decreased the strength a little.DOP acted either plasticizer or toughener to PVC,but it decre ased the efficiency of ENR toughened PVC.Antioxidant 4010 improved the mechanic al properties on PVC/ENR-50 blends.%对环氧化度为50%的环氧化天然橡胶(ENR-50)增韧 聚氯乙烯(PVC)体系的力学性能进行了研究,并分析了防老剂4010与增塑剂DOP对PVC/ENR增韧体系性能的影响。结果表明:ENR有较好的增韧效果,且对PVC的强度影响不大;DOP既可增塑也可增韧,但DOP的加入将影响ENR对PVC的增韧作用;防老剂4010可阻止ENR的老化,改善PVC/ENR-50共混物的性能。

  9. Raising trophy kids: The role of mothers' contingent self-esteem in maternal promotion of extrinsic goals.

    Science.gov (United States)

    Soenens, Bart; Wuyts, Dorien; Vansteenkiste, Maarten; Mageau, Geneviève A; Brenning, Katrijn

    2015-07-01

    This study examined the role of mothers' child-invested contingent self-esteem, that is, their tendency to hinge their self-worth on their child's achievements, in maternal promotion of extrinsic goals, as perceived by adolescents. It was also examined whether maternal promotion of extrinsic goals would, in turn, relate to adolescents' Social Dominance Orientation (SDO). Participants were 184 mothers and their adolescent children (66% female). Maternal child-invested contingent self-esteem predicted adolescent-perceived maternal promotion of extrinsic goals, even when taking into account the variance shared between the promotion of extrinsic goals and mothers' use of a controlling parenting style. Maternal child-invested contingent self-esteem also moderated associations between mothers' personal pursuit of extrinsic goals and their promotion of those goals, such that the association between mothers' own extrinsic goals and their promotion of those goals was significant only among mothers high on child-invested contingent self-esteem. Maternal promotion of extrinsic goals was, in turn, related to adolescent SDO, suggesting that the dynamics examined in this study ultimately relate to adolescents' social and ideological development. Copyright © 2015 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

  10. Coordination of intrinsic and extrinsic hand muscle activity as a function of wrist joint angle during two-digit grasping.

    Science.gov (United States)

    Johnston, Jamie A; Bobich, Lisa R; Santello, Marco

    2010-04-26

    Fingertip forces result from the activation of muscles that cross the wrist and muscles whose origins and insertions reside within the hand (extrinsic and intrinsic hand muscles, respectively). Thus, tasks that involve changes in wrist angle affect the moment arm and length, hence the force-producing capabilities, of extrinsic muscles only. If a grasping task requires the exertion of constant fingertip forces, the Central Nervous System (CNS) may respond to changes in wrist angle by modulating the neural drive to extrinsic or intrinsic muscles only or by co-activating both sets of muscles. To distinguish between these scenarios, we recorded electromyographic (EMG) activity of intrinsic and extrinsic muscles of the thumb and index finger as a function of wrist angle during a two-digit object hold task. We hypothesized that changes in wrist angle would elicit EMG amplitude modulation of the extrinsic and intrinsic hand muscles. In one experimental condition we asked subjects to exert the same digit forces at each wrist angle, whereas in a second condition subjects could choose digit forces for holding the object. EMG activity was significantly modulated in both extrinsic and intrinsic muscles as a function of wrist angle (both pmuscles. We conclude that the CNS controlled both extrinsic and intrinsic muscles as a muscle synergy. These findings are discussed within the theoretical frameworks of synergies and common neural input across motor nuclei of hand muscles. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

  11. Research progress of toughening modification of polylactic acid%聚乳酸增韧改性研究进展

    Institute of Scientific and Technical Information of China (English)

    肖伟娜; 黄雪; 冯光炷; 尹国强; 崔英德

    2011-01-01

    Polylactic acid ( PLA ) is widely used in agriculture, packaging, medicine and health care because it is a biocompatible, biodegradable and bioabsorbable polymer and has fine mechanical property. But it is hard and brittle and has poor pliability because it has a high glass transition temperature. Thus, it has to be modified to enhance its pliability to improve handling and application.In this paper, the recent research progress of toughening modification of PLA via copolymerization,cross-linking, and blending is reviewed.%聚乳酸因具有良好生物相容性、生物降解性、生物可吸收性以及优良的力学性能,在农业,食品包装、医疗卫生等领域得到了广泛应用,但因其玻璃化转变温度较高、性脆、柔韧性差,需通过增韧改性以提高其加工和应用性能.本文综述了聚乳酸通过共聚、交联、共混等改性方法增加柔韧性的最新研究进展.

  12. Effect of magnesium and nickel coatings on the wetting behavior of alumina toughened zirconia by molten Al-Mg alloy

    Science.gov (United States)

    Sharifi, H.; Khavandi, A. R.; Divandari, M.; Hasbullah, M. I.

    2012-01-01

    The wettability of alumina toughened zirconia (ZTA) by Al-Mg alloy was investigated using the sessile drop technique. The effects of nickel coating, magnesium content, nitrogen atmosphere, and processing temperature on the contact angle between the molten alloy and the substrate were determined. Likewise, the effect of these factors on the wetting properties was studied. The results showed that the nickel coating on the ceramic substrate caused a significant reduction in solid/liquid surface energy and the contact angle decreased obviously. The presence of magnesium in the molten aluminum alloy in nitrogen atmosphere reduced the contact angle effectively. The presence of magnesium in the alloy must be at a minimum amount of 2wt%-3wt%. Moreover, it was suggested that some chemical reactions in the Al-Mg-N system led to the production of Mg3N2 and AlN compositions. These compositions improved the wetting properties of the systems by reducing the surface energy of the molten. It was shown that increasing the temperature is also an effective factor for the enhancement of wetting properties.

  13. Nanofilled and/or toughened POM composites produced by water-mediated melt compounding: Structure and mechanical properties

    Directory of Open Access Journals (Sweden)

    2008-10-01

    Full Text Available Binary and ternary composites composed of polyoxymethylene (POM, polyurethane (PU and synthetic boehmite alumina (AlO(OH were produced by water-mediated melt compounding technique. PU latex and/or aqueous alumina suspension were injected into the molten POM in a twin-screw extruder to prepare toughened and/or reinforced polymer composites. The dispersion of the alumina and PU was studied by transmission- and scanning electron microcopy techniques (TEM and SEM, respectively, and discussed. The crystallization of the POM-based systems was inspected by polarized optical microscopy (PLM. The mechanical and thermomechanical properties of the composites were determined in dynamic-mechanical thermal analysis (DMTA, short-time creep tests (performed at various temperatures, uniaxial static tensile and notched Charpy impact tests. Incorporation of alumina increased the stiffness and resistance to creep and reduced the tensile strength, elongation at break and impact toughness. The change in the above parameters was opposite for the POM/PU binary blends. Additional incorporation of alumina in the POM/PU blend enhanced the resistance to creep, elongation at break and maintained the impact toughness compared to the POM/PU blend.

  14. Surface morphology changes and deuterium retention in Toughened, Fine-grained Recrystallized Tungsten under high-flux irradiation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Oya, M., E-mail: ohya@st.eie.eng.osaka-u.ac.jp [Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); Lee, H.T.; Ueda, Y. [Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); Kurishita, H. [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Oyaidzu, M.; Hayashi, T. [Fusion Research and Development Directorate, International Fusion Energy Research Center, Japan Atomic Energy Agency, Rokkasho-mura, Aomori 039-3212 (Japan); Yoshida, N. [Research Institute for Applied Mechanics, Kyushu University, Fukuoka (Japan); Morgan, T.W.; De Temmerman, G. [FOM Institute DIFFER Dutch Institute for Fundamental Energy Research, Nieuwegein 3439 MN (Netherlands)

    2015-08-15

    Surface morphology changes and deuterium (D) retention in Toughened, Fine-Grained Recrystallized Tungsten (TFGR W) with TaC dispersoids (W-TaC) and pure tungsten exposed to D plasmas to a fluence of 10{sup 26} D/m{sup 2} s were studied as a function of the D ion flux (10{sup 22}–10{sup 24} D/m{sup 2} s). As the flux increased from 10{sup 22} D/m{sup 2} s to 10{sup 24} D/m{sup 2} s, the numbers of blisters increased for both materials. However, smaller blisters were observed on W-TaC compared to pure W. In W-TaC, cracks beneath the surface along grain boundaries were observed, which were comparable to the blister sizes. The reason for the smaller blister sizes may arise from smaller grain sizes of W-TaC. In addition, reduction of the D retention in W-TaC was observed for higher flux exposures. D depth profiles indicate this reduction arises due to decrease in trapping in the bulk.

  15. A novel injectable, cohesive and toughened Si-HPMC (silanized-hydroxypropyl methylcellulose) composite calcium phosphate cement for bone substitution.

    Science.gov (United States)

    Liu, Weizhen; Zhang, Jingtao; Rethore, Gildas; Khairoun, Khalid; Pilet, Paul; Tancret, Franck; Bouler, Jean-Michel; Weiss, Pierre

    2014-07-01

    This study reports on the incorporation of the self-setting polysaccharide derivative hydrogel (silanized-hydroxypropyl methylcellulose, Si-HPMC) into the formulation of calcium phosphate cements (CPCs) to develop a novel injectable material for bone substitution. The effects of Si-HPMC on the handling properties (injectability, cohesion and setting time) and mechanical properties (Young's modulus, fracture toughness, flexural and compressive strength) of CPCs were systematically studied. It was found that Si-HPMC could endow composite CPC pastes with an appealing rheological behavior at the early stage of setting, promoting its application in open bone cavities. Moreover, Si-HPMC gave the composite CPC good injectability and cohesion, and reduced the setting time. Si-HPMC increased the porosity of CPCs after hardening, especially the macroporosity as a result of entrapped air bubbles; however, it improved, rather than compromised, the mechanical properties of composite CPCs, which demonstrates a strong toughening and strengthening effect. In view of the above, the Si-HPMC composite CPC may be particularly promising as bone substitute material for clinic application.

  16. La2Zr2O7 TBCs toughened by Pt particles prepared by cathode plasma electrolytic deposition

    Science.gov (United States)

    Deng, Shun-jie; Wang, Peng; He, Ye-dong; Zhang, Jin

    2016-06-01

    La2Zr2O7 thermal barrier coatings (TBCs) with dispersed Pt particles were prepared by cathode plasma electrolytic deposition (CPED) with ceramic balls added to the cathode region. Compared with the conventional CPED, when ceramic balls are used in the cathode region, the plasma discharge ignition current density decreases approximately 62-fold and the stable plasma discharges occur at the whole cathode surface. Such TBCs with a thickness of 100 μm exhibit a crack-free surface and are composed of pyrochlore-structured La2Zr2O7. Cyclic oxidation, scratching, and thermal insulation capability tests show that such TBCs not only exhibit high resistance to oxidation and spallation but also provide good thermal insulation. These beneficial effects are attributed to the excellent properties of TBCs, such as good thermal insulation because of low thermal conductivity, high-temperature oxidation resistance because of low-oxygen diffusion rate, and good mechanical properties because of the toughening effect of Pt particles.

  17. Investigation on the Strengthening and Toughening Mechanism of 500 MPa V-Nb Microalloyed Anti-Seismic Rebars

    Directory of Open Access Journals (Sweden)

    Wei CHEN

    2015-11-01

    Full Text Available Two types of 500 MPa anti-seismic rebars were produced by V-Nb microalloyed combined with controlled rolling and cooling technology, the strengthening and toughening mechanism of which were investigated. The complex phase microstructures of specimens consist of ferrite, pearlite and bainite (6 – 10 %. Furthermore, a large number of V(C,N and Nb(C,N precipitates with size of 5 – 30 nm formed in the ferrite matrix, grain boundaries and on dislocation lines, promoting the precipitation strengthening and inhibiting grain coarsening to controlled cooling microstructure. The mechanical performance of the steels was improved by solution and grain refinement strengthening, precipitation and microstructure strengthening. And the best strengthening effect was obtained by grain refinement, which increased the yield strength more than 35 % strength increment contribution ratio to yield strength. Moreover, about 16.5 % microstructure strengthening increment was obtained due to bainite formation. The plasticity and low-temperature toughness enhancement were mainly attributed to ferrite grain refinement improvement.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9710

  18. Surface modifications on toughened, fine-grained, recrystallized tungsten with repetitive ELM-like pulsed plasma irradiation

    Science.gov (United States)

    Kikuchi, Y.; Sakuma, I.; Kitagawa, Y.; Asai, Y.; Onishi, K.; Fukumoto, N.; Nagata, M.; Ueda, Y.; Kurishita, H.

    2015-08-01

    Surface modifications of toughened, fine-grained, recrystallized tungsten (TFGR W) materials with 1.1 wt.% TiC and 3.3 wt.% TaC dispersoids due to repetitive ELM-like pulsed (∼0.15 ms) helium plasma irradiation have been investigated by using a magnetized coaxial plasma gun. No surface cracking at the center part of the TFGR W samples exposed to 20 plasma pulses of ∼0.3 MJ m-2 was observed. The suppression of surface crack formation due to the increase of the grain boundary strength by addition of TiC and TaC dispersoids was confirmed in comparison with a pure W material. On the other hand, surface cracks and small pits appeared at the edge part of the TFGR W sample after the pulsed plasma irradiation. Erosion of the TiC and TaC dispersoids due to the pulsed plasma irradiation could cause the small pits on the surface, resulting in the surface crack formation.

  19. Surface modifications on toughened, fine-grained, recrystallized tungsten with repetitive ELM-like pulsed plasma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Y., E-mail: ykikuchi@eng.u-hyogo.ac.jp [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, 671-2280 Hyogo (Japan); Sakuma, I.; Kitagawa, Y.; Asai, Y.; Onishi, K.; Fukumoto, N.; Nagata, M. [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, 671-2280 Hyogo (Japan); Ueda, Y. [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Kurishita, H. [Institute for Materials Research, Tohoku University, Ibaraki 311-1313 (Japan)

    2015-08-15

    Surface modifications of toughened, fine-grained, recrystallized tungsten (TFGR W) materials with 1.1 wt.% TiC and 3.3 wt.% TaC dispersoids due to repetitive ELM-like pulsed (∼0.15 ms) helium plasma irradiation have been investigated by using a magnetized coaxial plasma gun. No surface cracking at the center part of the TFGR W samples exposed to 20 plasma pulses of ∼0.3 MJ m{sup −2} was observed. The suppression of surface crack formation due to the increase of the grain boundary strength by addition of TiC and TaC dispersoids was confirmed in comparison with a pure W material. On the other hand, surface cracks and small pits appeared at the edge part of the TFGR W sample after the pulsed plasma irradiation. Erosion of the TiC and TaC dispersoids due to the pulsed plasma irradiation could cause the small pits on the surface, resulting in the surface crack formation.

  20. Toughening of biodegradable polylactide/poly(butylene succinate-co-adipate) blends via in situ reactive compatibilization.

    Science.gov (United States)

    Ojijo, Vincent; Ray, Suprakas Sinha; Sadiku, Rotimi

    2013-05-22

    Polylactide and poly(butylene succinate-co-adipate) (PLA/PBSA) were melt-blended in the presence of triphenyl phosphite (TPP). An increase in the torque during melt mixing was used to monitor the changes in viscosity as compatibilization of the blends occurred. Scanning electron micrographs showed not only a reduction in the dispersed-phase size with increased TPP content but also fibrillated links between the PLA and PBSA phases, signifying compatibilization. Moreover, optimization of parameters such as the mixing sequence and time, TPP content, and PBSA concentration revealed that blends containing 30 and 10 wt % PBSA and 2 wt % TPP, which were processed for 30 min, were optimal in terms of thermomechanical properties. The impact strength increased from 6 kJ/m(2) for PLA to 11 and 16 kJ/m(2) for blends containing 30 and 10 wt % PBSA, respectively, whereas the elongation-at-break increased from 6% for PLA to 20 and 37% for blends containing 30 and 10 wt % PBSA, respectively. Upon compatibilization, the failure mode shifted from the brittle fracture of PLA to ductile deformation, effected by the debonding between the two phases. With improved phase adhesion, compatibilized blends not only were toughened but also did not significantly lose tensile strength and thermal stability.

  1. Interfacial toughening and consequent improvement in fracture toughness of carbon fiber reinforced epoxy resin composites: induced by diblock copolymers

    Directory of Open Access Journals (Sweden)

    X. D. Zhou

    2013-11-01

    Full Text Available Carbon fibers chemically grafted with hydroxyl-terminated diblock copolymer poly (n-butylacrylate-b-poly (glycidyl methacrylate (OH-PnBA-b-PGMA, were used as the reinforcement for epoxy composites. The multi-filament composite specimens were prepared and measured by dynamic mechanical analysis (DMA, to study the interfacial toughness of carbon fiber reinforced epoxy composites with the diblock copolymers. The loss modulus and loss factor peaks of β-relaxation indicated that composites with diblock copolymers could dissipate more energy at small strain and possess better interfacial toughness, whereas composites without the ductile block PnBA having the worse interfacial toughness. The glass transition temperature and the apparent activation energy calculated from the glass transition showed that the strong interfacial adhesion existed in the composites with diblock copolymers, corresponding with the value of interfacial shear strength. Therefore, a strengthening and toughening interfacial structure in carbon fiber/epoxy composites was achieved by introducing the diblock copolymer OH-PnBA-b-PGMA. The resulting impact toughness, characterized with an Izod impact tester, was better than that of composite without the ductile block PnBA.

  2. Toughening effect of bamboo flour/polypropylene foamed composite%竹粉/聚丙烯发泡复合材料的增韧效果

    Institute of Scientific and Technical Information of China (English)

    周吓星; 陈礼辉; 林巧佳

    2013-01-01

      为研发可代替聚丙烯(polypropylene,PP)应用于汽车内饰件的木塑复合材料,减少白色污染,节约化石能源,同时提高木塑复合材料的附加值,拓宽其应用领域.该文以注塑法制备竹粉/聚丙烯发泡复合材料,并分别采用乙烯-1-辛烯共聚物(polyolefin elastomer,POE)和马来酸酐接枝 POE(maleic anhydride grafted polyolefin elastomer,POE-g-MAH)增韧复合材料.研究了增韧填料对发泡复合材料力学性能的影响,用环境扫描电镜(environmental scanning electronic microscopy,ESEM)对复合材料的冲击断面进行观察,并进行了频率扫描的动态流变测试.结果表明:添加 POE 和 POE-g-MAH 在略微降低材料拉伸和弯曲强度的同时,可明显提高材料的缺口冲击强度,二者最佳用量分别为15%和8%;8%POE-g-MAH 增韧的复合材料的缺口冲击强度为8.55 kJ/m2,提高了35.7%,可很好地应用于汽车内饰件.ESEM 显示,增韧后,复合材料的断裂形式转变为韧性断裂.动态频率扫描结果显示,POE 对复合材料流变性能的影响较小,而 POE-g-MAH 增韧的复合材料的储能模量和复数黏度明显增大,且“第二平台”现象更为明显.%In order to make full use of bamboo resources in China and reduce white pollution, save fossil energy, the foamed composite of 54 wt% PP and 13 wt% HMSPP containing 33 wt% bamboo powder and 1% modified azodicarbonamide (AC) foaming agent blends was prepared by injection molding. Meanwhile, in order to substitute for polypropylene(PP) applied to automotive interior parts and thus broaden the application fields of wood-plastic composite, the bamboo powder/polypropylene foamed composites toughened by polyethylene octane elastomer (POE) and maleic anhydride grafted polyolefin elastomer (POE-g-MAH) were researched. Effects of the two toughen fillers on mechanical properties including bending, tensile and impact strengths were studied and the impact fractured surfaces of non-toughened

  3. A Novel Iterative Receiver Based on Extrinsic Information Update for MIMO Systems

    Institute of Scientific and Technical Information of China (English)

    LIN Wen-feng; HE Chen

    2007-01-01

    A novel iterative receiver for multiple input multiple output (MIMO) systems was introduced.Its basis concept is that the reliability of extrinsic information will be strengthened with continuous iterations.Extrinsic information of present iteration is added with prior information of last iteration to obtain performance gain.The simulation results show that the improved iterative receiver can approach the 5th iteration performance of conventional soft interference cancellation (SIC)-minimum mean square error (MMSE) iterative receiver after the 2nd iteration with less computational complexity.Compared with conventional iterative receiver, the improved iterative receiver has 1dB performance gain at bit error rate (BER) of 10-5, with four transmit antennas and four receive antennas system.

  4. Internal thermal origin mechanism of Karstic collapse column with no smoothly extrinsic cycle

    Institute of Scientific and Technical Information of China (English)

    LI Yong-jun; PENG Su-ping; LI Pei-quan; LIU Deng-xian; LIAN Hui-qing

    2008-01-01

    Huainan coal field as main object, investigation of Karstic hydrogeological conditions were developed in Huainan structureal unit, and the basic conditions, features and rules of Karstic growth were summarized. Geology background and causes of Karstic collapse columns were analyzed. Combined with ancient physiognomy, environment and litho-facies features. After studying synthetically Karstic collapse columns, shape of collapse body, filling feature, hydrodynamic condition and agglutinate material in Huainan area, considering mine hydrogeological conditions of Xuhuai coal field and referenced Karstic collapse columns characters of other mines in North China, the internal thermal origin theory is elementarily formed for Karstic collapse columns extrinsic cycle can not operate smoothly. Finaly, three aspects including distributing features of different kinds of Karstic collapse columns in north China type coal field, conditions of Karstic collapse columns origined from internal thermal with no smoothly extrinsic cycle, mechanics of causes were analyzed and demonstrated.

  5. Resolution limits of extrinsic Fabry-Perot interferometric displacement sensors utilizing wavelength scanning interrogation.

    Science.gov (United States)

    Ushakov, Nikolai; Liokumovich, Leonid

    2014-08-10

    The factors limiting the resolution of displacement sensors based on the extrinsic Fabry-Perot interferometer were studied. An analytical model giving the dependency of extrinsic Fabry-Perot interferometric (EFPI) resolution on the parameters of an optical setup and a sensor interrogator was developed. The proposed model enables one to either estimate the limit of possible resolution achievable with a given setup, or derive the requirements for optical elements and/or a sensor interrogator necessary for attaining the desired sensor resolution. An experiment supporting the analytical derivations was performed, demonstrating a large dynamic measurement range (with cavity length from tens of microns to 5 mm), a high baseline resolution (from 14 pm), and good agreement with the model.

  6. The inspiratory "squawk" in extrinsic allergic alveolitis and other pulmonary fibroses.

    Science.gov (United States)

    Earis, J E; Marsh, K; Pearson, M G; Ogilvie, C M

    1982-01-01

    An inspiratory musical sound ("squawk") was recorded in 14 patients with diffuse pulmonary fibrosis. These were divided into two groups: nine patients suffering from extrinsic allergic alveolitis (seven with bird fancier's lung and two with farmer's lung) and five patients with pulmonary fibrosis due to other causes, including rheumatoid disease, Wegener's granulomatosis, systemic sclerosis, and sarcoidosis. Clinical studies and phonopneumographic analysis of 10 consecutive squawks in each patient showed that the sound in the group with extrinsic allergic alveolitis was of shorter duration, occurred later in inspiration, and tended to be of higher frequency than the sound heard in the other group. Inspiratory crackles were present in all patients and in eight a single loud crackle preceded the squawk. We suggest that squawks, like crackles, result from the opening of airways and that the differences between the squawks in the two groups may reflect the size of the affected airways. PMID:7170682

  7. Estimating consumer preferences for extrinsic and intrinsic attributes of vegetables. A study of German consumers

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Guerrero, J. F.; Gazquez-Abad, J. C.; Huertas-Garcia, R.; Mondejar-Jimenez, J. A.

    2012-11-01

    Preference formation developed during the consumers evaluation of alternatives is one of the most important stages in models of consumer purchasing behaviour. This is especially true for the purchase of vegetables. The purpose of this paper is to analyze the role of extrinsic versus intrinsic attributes in the behaviour of consumer when purchasing cucumbers, considering four attributes; price, country of origin and production method (extrinsic), and freshness (intrinsic). Utilizing a sample of German tourists visiting the city of Almeria (Spain), conjoint analysis methodology is used. The results suggest that an intrinsic aspect (freshness) is the most important attribute for consumers. Therefore, marketers are advised to consider the importance of this attribute to the consumer and try to position the product in the destination markets on the basis of product freshness. (Author) 91 refs.

  8. Prelamin A causes progeria through cell-extrinsic mechanisms and prevents cancer invasion

    Science.gov (United States)

    de la Rosa, Jorge; Freije, José M. P.; Cabanillas, Rubén; Osorio, Fernando G.; Fraga, Mario F.; Fernández-García, M. Soledad; Rad, Roland; Fanjul, Víctor; Ugalde, Alejandro P.; Liang, Qi; Prosser, Haydn M.; Bradley, Allan; Cadiñanos, Juan; López-Otín, Carlos

    2013-01-01

    Defining the relationship between ageing and cancer is a crucial but challenging task. Mice deficient in Zmpste24, a metalloproteinase mutated in human progeria and involved in nuclear prelamin A maturation, recapitulate multiple features of ageing. However, their short lifespan and serious cell-intrinsic and cell-extrinsic alterations restrict the application and interpretation of carcinogenesis protocols. Here we present Zmpste24 mosaic mice that lack these limitations. Zmpste24 mosaic mice develop normally and keep similar proportions of Zmpste24-deficient (prelamin A accumulating) and Zmpste24-proficient (mature lamin A containing) cells throughout life, revealing that cell-extrinsic mechanisms are preeminent for progeria development. Moreover, prelamin A accumulation does not impair tumour initiation and growth, but it decreases the incidence of infiltrating oral carcinomas. Accordingly, silencing of ZMPSTE24 reduces human cancer cell invasiveness. Our results support the potential of cell-based and systemic therapies for progeria and highlight ZMPSTE24 as a new anticancer target. PMID:23917225

  9. Prelamin A causes progeria through cell-extrinsic mechanisms and prevents cancer invasion.

    Science.gov (United States)

    de la Rosa, Jorge; Freije, José M P; Cabanillas, Rubén; Osorio, Fernando G; Fraga, Mario F; Fernández-García, M Soledad; Rad, Roland; Fanjul, Víctor; Ugalde, Alejandro P; Liang, Qi; Prosser, Haydn M; Bradley, Allan; Cadiñanos, Juan; López-Otín, Carlos

    2013-01-01

    Defining the relationship between ageing and cancer is a crucial but challenging task. Mice deficient in Zmpste24, a metalloproteinase mutated in human progeria and involved in nuclear prelamin A maturation, recapitulate multiple features of ageing. However, their short lifespan and serious cell-intrinsic and cell-extrinsic alterations restrict the application and interpretation of carcinogenesis protocols. Here we present Zmpste24 mosaic mice that lack these limitations. Zmpste24 mosaic mice develop normally and keep similar proportions of Zmpste24-deficient (prelamin A-accumulating) and Zmpste24-proficient (mature lamin A-containing) cells throughout life, revealing that cell-extrinsic mechanisms are preeminent for progeria development. Moreover, prelamin A accumulation does not impair tumour initiation and growth, but it decreases the incidence of infiltrating oral carcinomas. Accordingly, silencing of ZMPSTE24 reduces human cancer cell invasiveness. Our results support the potential of cell-based and systemic therapies for progeria and highlight ZMPSTE24 as a new anticancer target.

  10. Intrinsic and extrinsic motivation in early adolescents' friendship development: friendship selection, influence, and prospective friendship quality.

    Science.gov (United States)

    Ojanen, Tiina; Sijtsema, Jelle J; Hawley, Patricia H; Little, Todd D

    2010-12-01

    Friendships are essential for adolescent social development. However, they may be pursued for varying motives, which, in turn, may predict similarity in friendships via social selection or social influence processes, and likely help to explain friendship quality. We examined the effect of early adolescents' (N = 374, 12-14 years) intrinsic and extrinsic friendship motivation on friendship selection and social influence by utilizing social network modeling. In addition, longitudinal relations among motivation and friendship quality were estimated with structural equation modeling. Extrinsic motivation predicted activity in making friendship nominations during the sixth grade and lower friendship quality across time. Intrinsic motivation predicted inactivity in making friendship nominations during the sixth, popularity as a friend across the transition to middle school, and higher friendship quality across time. Social influence effects were observed for both motives, but were more pronounced for intrinsic motivation.

  11. Intrinsic motivation, extrinsic motivation, and learning English as a foreign language.

    Science.gov (United States)

    Shaikholeslami, Razieh; Khayyer, Mohammad

    2006-12-01

    The objective of this study was to examine the relationships of amotivation, extrinsic motivation, and intrinsic motivation with learning the English language. The 230 Iranian students at Shiraz University were tested using the Language Learning Orientations Scales to measure Amotivation, Extrinsic Motivation, and Intrinsic Motivation as explanatory variables. Grade point average in English exams was selected as a measure of English learning Achievement. Multiple regression analysis revealed that learning Achievement scores were predicted by scores on the Amotivation subscale, Introjected Regulation subscale, Knowledge subscale, and Stimulation subscale, whereas, the External and Identified Regulation and Accomplishment subscales did not have a significant relationship with Achievement. The results are discussed in terms of differences in Iranian context and culture.

  12. Extrinsic electromagnetic chirality in all-photodesigned one-dimensional THz metamaterials

    CERN Document Server

    Rizza, Carlo; Brambilla, Massimo; Prati, Franco; Ciattoni, Alessandro

    2016-01-01

    We suggest that all-photodesigned metamaterials, sub-wavelength custom patterns of photo-excited carriers on a semiconductor, can display an exotic extrinsic electromagnetic chirality in terahertz (THz) frequency range. We consider a photo-induced pattern exhibiting 1D geometrical chirality, i.e. its mirror image can not be superposed onto itself by translations without rotations and, in the long wavelength limit, we evaluate its bianisotropic response. The photo-induced extrinsic chirality turns out to be fully reconfigurable by recasting the optical illumination which supports the photo-excited carriers. The all-photodesigning technique represents a feasible, easy and powerful method for achieving effective matter functionalization and, combined with the chiral asymmetry, it could be the platform for a new generation of reconfigurable devices for THz wave polarization manipulation.

  13. The CNS stochastically selects motor plan utilizing extrinsic and intrinsic representations.

    Science.gov (United States)

    Kodl, Jindrich; Ganesh, Gowrishankar; Burdet, Etienne

    2011-01-01

    Traditionally motor studies have assumed that motor tasks are executed according to a single plan characterized by regular patterns, which corresponds to the minimum of a cost function in extrinsic or intrinsic coordinates. However, the novel via-point task examined in this paper shows distinct planning and execution stages in motion production and demonstrates that subjects randomly select from several available motor plans to perform a task. Examination of the effect of pre-training and via-point orientation on subject behavior reveals that the selection of a plan depends on previous movements and is affected by constraints both intrinsic and extrinsic of the body. These results provide new insights into the hierarchical structure of motion planning in humans, which can only be explained if the current models of motor control integrate an explicit plan selection stage.

  14. The CNS stochastically selects motor plan utilizing extrinsic and intrinsic representations.

    Directory of Open Access Journals (Sweden)

    Jindrich Kodl

    Full Text Available Traditionally motor studies have assumed that motor tasks are executed according to a single plan characterized by regular patterns, which corresponds to the minimum of a cost function in extrinsic or intrinsic coordinates. However, the novel via-point task examined in this paper shows distinct planning and execution stages in motion production and demonstrates that subjects randomly select from several available motor plans to perform a task. Examination of the effect of pre-training and via-point orientation on subject behavior reveals that the selection of a plan depends on previous movements and is affected by constraints both intrinsic and extrinsic of the body. These results provide new insights into the hierarchical structure of motion planning in humans, which can only be explained if the current models of motor control integrate an explicit plan selection stage.

  15. Multicamera system extrinsic stability analysis and large-span truss string structure displacement measurement.

    Science.gov (United States)

    Liu, Cong; Dong, Shuai; Mokhtar, Mohammed; He, Xiaoyuan; Lu, Jinyu; Wu, Xiaolong

    2016-10-10

    A novel technique for measuring the displacements of large-span truss string structures that employs multicamera systems is proposed. The coordinates of the stereo-vision systems are unified in a single global coordinate system by employing 3D data reconstructed using close-range photogrammetry. To estimate the camera's attitude motions during an experiment, an instantaneous extrinsic rectification algorithm was developed. Experiments in which a camera was rotated and translated were conducted to verify the accuracy and precision of the developed algorithm. In addition, the proposed multicamera systems were employed to analyze a large-span truss string structure. The displacement results obtained from numerical simulations and experiments using pre-calibration and rectification methods are compared in this paper, and the stability of the camera's extrinsic parameters is discussed.

  16. Examining the relationship between recreational sport participation and intrinsic and extrinsic motivation and amotivation.

    Science.gov (United States)

    Tsorbatzoudis, Haralambos; Alexandris, Konstantinos; Zahariadis, Panagiotis; Grouios, George

    2006-10-01

    This study aimed at investigating the effect of motivational dimensions proposed by Pelletier, et al. in 1995, both on sport participation levels and on intention for continuing participation among adult recreational sport participants. Two hundred and fifty-seven adult individuals, who reported participation in some type of sport and physical activity, completed the Sport Motivation Scale and a scale measuring intention. The study provided evidence to suggest that increased motivation leads to increased participation. Amotivation significantly decreased from the least to the most frequent participant groups, while both extrinsic and intrinsic motivation followed the reverse pattern. The results also indicated that increased intrinsic motivation to gain knowledge and accomplishment and extrinsic motivation (introjected regulation) are positively correlated with individuals' intentions to continue participation, while amotivation is negatively related. These results provide limited support for the self-determination theory. Implications for sport participation promotion are discussed.

  17. A curve fitting method for extrinsic camera calibration from a single image of a cylindrical object

    Science.gov (United States)

    Winkler, A. W.; Zagar, B. G.

    2013-08-01

    An important step in the process of optical steel coil quality assurance is to measure the proportions of width and radius of steel coils as well as the relative position and orientation of the camera. This work attempts to estimate these extrinsic parameters from single images by using the cylindrical coil itself as the calibration target. Therefore, an adaptive least-squares algorithm is applied to fit parametrized curves to the detected true coil outline in the acquisition. The employed model allows for strictly separating the intrinsic and the extrinsic parameters. Thus, the intrinsic camera parameters can be calibrated beforehand using available calibration software. Furthermore, a way to segment the true coil outline in the acquired images is motivated. The proposed optimization method yields highly accurate results and can be generalized even to measure other solids which cannot be characterized by the identification of simple geometric primitives.

  18. "Coveting thy neighbour's legs": a qualitative study of exercisers' experiences of intrinsic and extrinsic goal pursuit.

    Science.gov (United States)

    Sebire, Simon J; Standage, Martyn; Gillison, Fiona B; Vansteenkiste, Maarten

    2013-06-01

    Goals are central to exercise motivation, although not all goals (e.g., health vs. appearance goals) are equally psychologically or behaviorally adaptive. Within goal content theory (Vansteenkiste, Niemiec, & Soenens, 2010), goals are adaptive to the extent to which they satisfy psychological needs for autonomy, competence, and relatedness. However, little is known about what exercisers pursuing different goals are feeling, doing, thinking, and paying attention to that may help to explain the association between goal contents and need satisfaction. Using semistructured interviews and interpretative phenomenological analysis, we explored experiences of exercise among 11 adult exercisers who reported pursuing either predominantly intrinsic or extrinsic goals. Four themes emerged: (a) observation of others and resulting emotions, (b) goal expectations and time perspective, (c) markers of progress and (d) reactions to (lack of) goal achievement. Intrinsic and extrinsic goal pursuers reported divergent experiences within these four domains. The findings illuminate potential mechanisms by which different goals may influence psychological and behavioral outcomes in the exercise context.

  19. Glutathione depletion regulates both extrinsic and intrinsic apoptotic signaling cascades independent from multidrug resistance protein 1

    OpenAIRE

    2014-01-01

    Glutathione (GSH) depletion is an important hallmark of apoptosis. We previously demonstrated that GSH depletion, by its efflux, regulates apoptosis by modulation of executioner caspase activity. However, both the molecular identity of the GSH transporter(s) involved and the signaling cascades regulating GSH loss remain obscure. We sought to determine the role of multidrug resistance protein 1 (MRP1) in GSH depletion and its regulatory role on extrinsic and intrinsic pathways of apoptosis. In...

  20. [Extrinsic allergic alveolitis: An initial form of presentation as a fever of unknown origin].

    Science.gov (United States)

    Peña Irún, A; García Pérez, M; González Santamaría, A

    2012-10-01

    Extrinsic allergic alveolitis is characterised by an inflammatory immune process with pulmonary impairment caused by inhalation of organic dust. It is considered an occupational disease and is a very significant cause of temporary and permanent disability that can be prevented. The diagnosis is not often easy, but it is important to make it in the early stages, when the disease is still reversible. Copyright © 2011 Elsevier España, S.L. y SEMERGEN. All rights reserved.

  1. Effects of extrinsic mortality on the evolution of aging: a stochastic modeling approach.

    Science.gov (United States)

    Shokhirev, Maxim Nikolaievich; Johnson, Adiv Adam

    2014-01-01

    The evolutionary theories of aging are useful for gaining insights into the complex mechanisms underlying senescence. Classical theories argue that high levels of extrinsic mortality should select for the evolution of shorter lifespans and earlier peak fertility. Non-classical theories, in contrast, posit that an increase in extrinsic mortality could select for the evolution of longer lifespans. Although numerous studies support the classical paradigm, recent data challenge classical predictions, finding that high extrinsic mortality can select for the evolution of longer lifespans. To further elucidate the role of extrinsic mortality in the evolution of aging, we implemented a stochastic, agent-based, computational model. We used a simulated annealing optimization approach to predict which model parameters predispose populations to evolve longer or shorter lifespans in response to increased levels of predation. We report that longer lifespans evolved in the presence of rising predation if the cost of mating is relatively high and if energy is available in excess. Conversely, we found that dramatically shorter lifespans evolved when mating costs were relatively low and food was relatively scarce. We also analyzed the effects of increased predation on various parameters related to density dependence and energy allocation. Longer and shorter lifespans were accompanied by increased and decreased investments of energy into somatic maintenance, respectively. Similarly, earlier and later maturation ages were accompanied by increased and decreased energetic investments into early fecundity, respectively. Higher predation significantly decreased the total population size, enlarged the shared resource pool, and redistributed energy reserves for mature individuals. These results both corroborate and refine classical predictions, demonstrating a population-level trade-off between longevity and fecundity and identifying conditions that produce both classical and non

  2. Effects of extrinsic mortality on the evolution of aging: a stochastic modeling approach.

    Directory of Open Access Journals (Sweden)

    Maxim Nikolaievich Shokhirev

    Full Text Available The evolutionary theories of aging are useful for gaining insights into the complex mechanisms underlying senescence. Classical theories argue that high levels of extrinsic mortality should select for the evolution of shorter lifespans and earlier peak fertility. Non-classical theories, in contrast, posit that an increase in extrinsic mortality could select for the evolution of longer lifespans. Although numerous studies support the classical paradigm, recent data challenge classical predictions, finding that high extrinsic mortality can select for the evolution of longer lifespans. To further elucidate the role of extrinsic mortality in the evolution of aging, we implemented a stochastic, agent-based, computational model. We used a simulated annealing optimization approach to predict which model parameters predispose populations to evolve longer or shorter lifespans in response to increased levels of predation. We report that longer lifespans evolved in the presence of rising predation if the cost of mating is relatively high and if energy is available in excess. Conversely, we found that dramatically shorter lifespans evolved when mating costs were relatively low and food was relatively scarce. We also analyzed the effects of increased predation on various parameters related to density dependence and energy allocation. Longer and shorter lifespans were accompanied by increased and decreased investments of energy into somatic maintenance, respectively. Similarly, earlier and later maturation ages were accompanied by increased and decreased energetic investments into early fecundity, respectively. Higher predation significantly decreased the total population size, enlarged the shared resource pool, and redistributed energy reserves for mature individuals. These results both corroborate and refine classical predictions, demonstrating a population-level trade-off between longevity and fecundity and identifying conditions that produce both

  3. Please Say What This Word Is ? Vowel-extrinsic normalization in the sensorimotor control of speech

    OpenAIRE

    Nicolas J. Bourguignon; Shari R Baum; Shiller, Douglas M.

    2016-01-01

    The extent to which the adaptive nature of speech perception influences the acoustic targets underlying speech production is not well understood. For example, listeners can rapidly accommodate to talker-dependent phonetic properties ? a process known as vowel-extrinsic normalization ? without altering their speech output. Recent evidence, however, shows that reinforcement-based learning in vowel perception alters the processing of speech auditory feedback, impacting sensorimotor control durin...

  4. Sequential intrinsic and extrinsic geometry calibration in fluoro CT imaging with a mobile C-arm

    Science.gov (United States)

    Cheryauka, Arvi; Breham, Sebastien; Christensen, Wayne

    2006-03-01

    Design of C-arm equipment with 3D imaging capabilitys involves retrieval of repeatable gantry positioning information along the acquisition trajectory. Inaccurate retrieval or improper use of positioning information may cause degradation of the reconstruction results, appearance of image artifacts, or indicate false structures. The geometry misrepresentation can also lead to the errors in relative pose assessment of anatomy-of-interest and interventional tools. Comprehensive C gantry calibration with an extended set of misalignment and motion parameters suffers from ambiguity caused by parameter cross-correlation and significant computational complexity. We deploy the concept of a waterfall calibration that comprises sequential intrinsic and extrinsic geometry calibration delineation steps. Following the image-based framework, the first step in our method is intrinsic calibration that deals with delineation of geometry of the X-ray tube-Detector assembly. Extrinsic parameters define motion of the C-arm assembly in 3D space and relate the Camera and World coordinate systems. We formulate both intrinsic and extrinsic calibration problems in vectorized form with total variation constraints. The proposed method has been verified by numerical design and validated by experimental studies. Sequential delineation of intrinsic and extrinsic geometries has demonstrated very efficient performance. The method eliminates the cross-correlation between cone-beam projection parameters, provides significantly better accuracy and computational speed, simplifies the structures of calibration targets used, and avoids the unnecessary workflow and image processing steps. It appears to be adequate for quality and cost derivations in an interventional surgery settings using a mobile C-arm.

  5. Charge Separation in Semicrystalline Polymeric Semiconductors by Photoexcitation: Is the Mechanism Intrinsic or Extrinsic?

    Science.gov (United States)

    Paquin, Francis; Latini, Gianluca; Sakowicz, Maciej; Karsenti, Paul-Ludovic; Wang, Linjun; Beljonne, David; Stingelin, Natalie; Silva, Carlos

    2011-05-01

    We probe charge photogeneration and subsequent recombination dynamics in neat regioregular poly(3-hexylthiophene) films over six decades in time by means of time-resolved photoluminescence spectroscopy. Exciton dissociation at 10 K occurs extrinsically at interfaces between molecularly ordered and disordered domains. Polaron pairs thus produced recombine by tunneling with distributed rates governed by the distribution of electron-hole radii. Quantum-chemical calculations suggest that hot-exciton dissociation at such interfaces results from a high charge-transfer character.

  6. Text Summarization Evaluation: Correlating Human Performance on an Extrinsic Task with Automatic Intrinsic Metrics

    Science.gov (United States)

    2006-05-01

    computed the Pearson r and Spearman ρ (Siegel and Castellan , 1988) correlation values for the comparison of the human judgments and the ROUGE scores, and...average performance of a system for all topics. Table 4.15 and Table 4.16 show the rank correlations— using Pearson r (Siegel and Castellan , 1988...Intrinsic and Extrinsic Scores Grouped by System (including Full Text) and also Spearman ρ (Siegel and Castellan , 1988) is introduced in this

  7. Modeling effects of intrinsic and extrinsic rewards on the competition between striatal learning systems.

    Science.gov (United States)

    Boedecker, Joschka; Lampe, Thomas; Riedmiller, Martin

    2013-01-01

    A common assumption in psychology, economics, and other fields holds that higher performance will result if extrinsic rewards (such as money) are offered as an incentive. While this principle seems to work well for tasks that require the execution of the same sequence of steps over and over, with little uncertainty about the process, in other cases, especially where creative problem solving is required due to the difficulty in finding the optimal sequence of actions, external rewards can actually be detrimental to task performance. Furthermore, they have the potential to undermine intrinsic motivation to do an otherwise interesting activity. In this work, we extend a computational model of the dorsomedial and dorsolateral striatal reinforcement learning systems to account for the effects of extrinsic and intrinsic rewards. The model assumes that the brain employs both a goal-directed and a habitual learning system, and competition between both is based on the trade-off between the cost of the reasoning process and value of information. The goal-directed system elicits internal rewards when its models of the environment improve, while the habitual system, being model-free, does not. Our results account for the phenomena that initial extrinsic reward leads to reduced activity after extinction compared to the case without any initial extrinsic rewards, and that performance in complex task settings drops when higher external rewards are promised. We also test the hypothesis that external rewards bias the competition in favor of the computationally efficient, but cruder and less flexible habitual system, which can negatively influence intrinsic motivation and task performance in the class of tasks we consider.

  8. Modeling effects of intrinsic and extrinsic rewards on the competition between striatal learning systems

    Directory of Open Access Journals (Sweden)

    Joschka eBoedecker

    2013-10-01

    Full Text Available A common assumption in psychology, economics, and other fields holds that higher performance will result if extrinsic rewards (such as money are offered as an incentive. While this principle seems to work well for tasks that require the execution of the same sequence of steps over and over, with little uncertainty about the process, in other cases, especially where creative problem solving is required due to the difficulty in finding the optimal sequence of actions, external rewards can actually be detrimental to task performance. Furthermore, they have the potential to undermine intrinsic motivation to do an otherwise interesting activity. In this work, we extend a computational model of the prefrontal and dorsolateral striatal reinforcement learning systems to account for the effects of extrinsic and intrinsic rewards. The model assumes that the brain employs both a goal-directed and a habitual learning system, and competition between both is based on the trade-off between the cost of the reasoning process and value of information. The goal-directed system elicits internal rewards when its models of the environment improve, while the habitual system, being model-free, does not. Our results account for the phenomena that initial extrinsic reward leads to reduced activity after extinction compared to the case without any initial extrinsic rewards, and that performance in complex task settings drops when higher external rewards are promised. We also test the hypothesis that external rewards bias the competition in favor of the computationally efficient, but cruder and less flexible habitual system, which can negatively influence intrinsic motivation and task performance in the class of tasks we consider.

  9. Modeling effects of intrinsic and extrinsic rewards on the competition between striatal learning systems

    OpenAIRE

    Joschka eBoedecker; Thomas eLampe; Martin eRiedmiller

    2013-01-01

    A common assumption in psychology, economics, and other fields holds that higher performance will result if extrinsic rewards (such as money) are offered as an incentive. While this principle seems to work well for tasks that require the execution of the same sequence of steps over and over, with little uncertainty about the process, in other cases, especially where creative problem solving is required due to the difficulty in finding the optimal sequence of actions, external rewards can actu...

  10. Modeling effects of intrinsic and extrinsic rewards on the competition between striatal learning systems

    OpenAIRE

    Joschka eBoedecker; Thomas eLampe; Martin eRiedmiller

    2013-01-01

    A common assumption in psychology, economics, and other fields holds that higher performance will result if extrinsic rewards (such as money) are offered as an incentive. While this principle seems to work well for tasks that require the execution of the same sequence of steps over and over, with little uncertainty about the process, in other cases, especially where creative problem solving is required due to the difficulty in finding the optimal sequence of actions, external rewards can actu...

  11. Careful accounting of extrinsic noise in protein expression reveals correlations among its sources

    Science.gov (United States)

    Cole, John A.; Luthey-Schulten, Zaida

    2017-06-01

    In order to grow and replicate, living cells must express a diverse array of proteins, but the process by which proteins are made includes a great deal of inherent randomness. Understanding this randomness—whether it arises from the discrete stochastic nature of chemical reactivity ("intrinsic" noise), or from cell-to-cell variability in the concentrations of molecules involved in gene expression, or from the timings of important cell-cycle events like DNA replication and cell division ("extrinsic" noise)—remains a challenge. In this article we analyze a model of gene expression that accounts for several extrinsic sources of noise, including those associated with chromosomal replication, cell division, and variability in the numbers of RNA polymerase, ribonuclease E, and ribosomes. We then attempt to fit our model to a large proteomics and transcriptomics data set and find that only through the introduction of a few key correlations among the extrinsic noise sources can we accurately recapitulate the experimental data. These include significant correlations between the rate of mRNA degradation (mediated by ribonuclease E) and the rates of both transcription (RNA polymerase) and translation (ribosomes) and, strikingly, an anticorrelation between the transcription and the translation rates themselves.

  12. Identity Processes and Intrinsic and Extrinsic Goal Pursuits: Directionality of Effects in College Students.

    Science.gov (United States)

    Luyckx, Koen; Duriez, Bart; Green, Lindsey M; Negru-Subtirica, Oana

    2017-08-01

    Identity research has mainly focused on the degree to which adolescents and emerging adults engage in exploration and commitment to identity goals and strivings. Somewhat lacking from this research tradition is an explicit focus on the content of the identity goals that individuals deem important and pursue. The present manuscript describes two longitudinal studies sampling college students in which we examine how exploration and commitment processes relate to intrinsic and extrinsic goal pursuits as defined in Self-Determination Theory. Study 1 was a two-wave longitudinal study spanning 6 months (N = 370; 77.4% women; mean age 18.24 years); Study 2 was a three-wave longitudinal study spanning 6 months (N = 458 students; 84.9% women; mean age 18.25 years). Using cross-lagged path analyses, hypotheses were supported to various degrees of convergence between studies, pointing to the extent of which results were replicated across our two independent longitudinal samples. Whereas an intrinsic goal orientation positively predicted commitment making (Study 1) and identification with commitment over time (Studies 1 and 2), an extrinsic goal orientation positively predicted ruminative exploration over time, which led to decreases in intrinsic orientation over time (Study 2). Further, an intrinsic goal orientation negatively predicted ruminative exploration over time (Study 1). The findings in for pro-active exploration processes were inconsistent across both studies, being prospectively related to both intrinsic (Study 2) and extrinsic goal orientations (Study 1). Implications and suggestions for future research are discussed.

  13. Intrinsic and extrinsic noise effects on phase transitions of network models with applications to swarming systems.

    Science.gov (United States)

    Pimentel, Jaime A; Aldana, Maximino; Huepe, Cristián; Larralde, Hernán

    2008-06-01

    We analyze order-disorder phase transitions driven by noise that occur in two kinds of network models closely related to the self-propelled model proposed by Vicsek [Phys. Rev. Lett. 75, 1226 (1995)] to describe the collective motion of groups of organisms. Two different types of noise, which we call intrinsic and extrinsic, are considered. The intrinsic noise, the one used by Vicsek in their original work, is related to the decision mechanism through which the particles update their positions. In contrast, the extrinsic noise, later introduced by Grégoire and Chaté [Phys. Rev. Lett. 92, 025702 (2004)], affects the signal that the particles receive from the environment. The network models presented here can be considered as mean-field representations of the self-propelled model. We show analytically and numerically that, for these two network models, the phase transitions driven by the intrinsic noise are continuous, whereas the extrinsic noise produces discontinuous phase transitions. This is true even for the small-world topology, which induces strong spatial correlations between the network elements. We also analyze the case where both types of noise are present simultaneously. In this situation, the phase transition can be continuous or discontinuous depending upon the amplitude of each type of noise.

  14. Comparing Effects of Intrinsic and Extrinsic Social Values Between Younger and Older Employees.

    Science.gov (United States)

    Yeung, Dannii Y; Fung, Helene H; Chan, Darius K-S

    2016-08-17

    Socioemotional selectivity theory proposes that older adults emphasize emotional goals and interpersonal closeness to a greater extent than do younger adults, suggesting that holding social work-related values (SWVs) may be beneficial to older employees. This project aimed at examining two dimensions of SWVs, intrinsic and extrinsic SWVs, and tested whether age and work situation would moderate their effects on self-rated job performance. A cross-sectional survey (Study 1, N = 357) and a 14-day experience sampling study (Study 2, N = 77) were conducted among Chinese managerial employees. Study 1 showed that the direct effect of intrinsic SWVs on self-rated job performance was stronger in older employees than in younger employees. Study 2 demonstrated that older employees who valued intrinsic SWVs while being in social situations performed much better than when they did not value intrinsic SWVs but being in social situations; however such positive effect was not shown in younger employees. Findings of this project reveal that the effect of SWVs varies across locus of effect (intrinsic versus extrinsic), age, and work situation. Among older employees, the positive effect of intrinsic SWVs is more crucial than that of extrinsic SWVs on self-rated job performance. Findings of this project imply that intrinsically rewarding incentives would be more effective in motivating older employees to reach peak performance.

  15. Combination of extrinsic and intrinsic pathways significantly accelerates axial vascularization of bioartificial tissues.

    Science.gov (United States)

    Arkudas, Andreas; Pryymachuk, Galyna; Beier, Justus P; Weigel, Linda; Körner, Carolin; Singer, Robert F; Bleiziffer, Oliver; Polykandriotis, Elias; Horch, Raymund E; Kneser, Ulrich

    2012-01-01

    In this study, the authors present a modification of the arteriovenous loop model that combines extrinsic and intrinsic vascularization modes to enhance vascularization of bioartificial matrices. An arteriovenous loop was created in the medial thighs of 24 rats. The loop was placed in a newly developed titanium chamber, which was fabricated with an electron beam melting facility, and was embedded in a hydroxyapatite/β-tricalcium phosphate/fibrin matrix. At the explantation time points (2, 4, 6, and 8 weeks), constructs were perfused by differently colored dyes to determine the amount of tissue vascularized by either the intrinsic or the extrinsic vascular pathway. Specimens were investigated by means of micro-computed tomography and histologic and morphometric analysis. Although there was an equal number of blood vessels originating from the center and the periphery, 83 percent of all vessels displayed a connection to the arteriovenous loop already at 2 weeks. There was a continuous increase of the relative proportion of vessels connected to the arteriovenous loop over time detectable. At 8 weeks, communications between the newly formed vessels and the arteriovenous loop were visible in 97 percent of all vessels. This study demonstrates for the first time the enhancement of angiogenesis in an axially vascularized tissue by an additional extrinsic vascular pathway. By 2 weeks, both pathways showed connections, allowing transplantation of the entire construct using the arteriovenous loop pedicle. This approach will allow for reduction of the time interval between arteriovenous loop implantation and transplantation into the defect site and limitation of operative interventions.

  16. Using humour as an extrinsic source of emotion regulation in young and older adults.

    Science.gov (United States)

    Harm, Jonathan; Vieillard, Sandrine; Didierjean, André

    2014-10-01

    It has been suggested that intrinsic abilities for regulating emotions remain stable or improve with ageing, but, to date, no studies have examined age-related differences in extrinsic emotion regulation. Since humour has been found to be an effective form of emotion regulation, we used a paradigm similar to that of Strick and colleagues (2009) with two objectives: to compare extrinsic humorous emotion regulation in young and older adults and to test whether the potential beneficial effect of humour on negative emotion is better explained by the cognitive distraction hypothesis or by the positive affect elicitation hypothesis. To this end, neutral, moderately, and strongly negative pictures followed by humorous, simply positive, or weird cartoons, controlled for both their funniness and cognitive demands, were presented to 26 young and 25 older adults with the instruction to report their negative feelings. When induced to feel moderately negative emotions, both young and older adults reported a lower negative feeling after viewing the humorous cartoons than after the other ones. This indicates that the extrinsic humorous emotion regulation skill remains stable with ageing and suggests that the beneficial effect of humour on emotional feeling cannot be seen as a purely cognitive distraction.

  17. Extrinsic Versus Intrinsic Benefits: Challenging Categories Used to Define the Value of Music in Schools

    Directory of Open Access Journals (Sweden)

    Alexander Hew Dale Crooke

    2016-07-01

    Full Text Available Increasing pressures to justify the value of music in schools over recent decades has led to the construction of three distinct areas of benefits: intrinsic (or musical benefits, extrinsic benefits related to academic and/or cognitive development, and extrinsic benefits related to psychosocial wellbeing. While some argue these categories have been useful for identifying specific areas of value and enabling targeted advocacy approaches, others have challenged this segmented approach to justification. While the most strident point of contention stems from the perception that categories which champion non-musical (extrinsic benefits have led to the devaluing of musical (intrinsic benefits, others dispute the categories themselves. Such arguments question the ability to separate what have been categorised as musical and non-musical elements, particularly in relation to social and political elements. This paper aims to tease out the practicality of these existing categories, and in doing so, challenge their robustness in both form and definition. The argument is made that current attempts to separate the value of school-based music into distinct categories is not only unclear, but also unhelpful in areas of advocacy. This argument rests on the premise that musical participation affords opportunities to enrich human experience in holistic and integrated ways, and that categorisation serves to preclude this unique value.

  18. The effects of non-contingent extrinsic and intrinsic rewards on memory consolidation.

    Science.gov (United States)

    Nielson, Kristy A; Bryant, Ted

    2005-07-01

    Emotional and arousing treatments given shortly after learning enhance delayed memory retrieval in animal and human studies. Positive affect and reward induced prior to a variety of cognitive tasks enhance performance, but their ability to affect memory consolidation has not been investigated before. Therefore, we investigated the effects of a small, non-contingent, intrinsic or extrinsic reward on delayed memory retrieval. Participants (n=108) studied and recalled a list of 30 affectively neutral, imageable nouns. Experimental groups were then given either an intrinsic reward (e.g., praise) or an extrinsic reward (e.g., US 1 dollar). After a one-week delay, participants' retrieval performance for the word list was significantly better in the extrinsic reward groups, whether the reward was expected or not, than in controls. Those who received the intrinsic reward performed somewhat better than controls, but the difference was not significant. Thus, at least some forms of arousal and reward, even when semantically unrelated to the learned material, can effectively modulate memory consolidation. These types of treatments might be useful for the development of new memory intervention strategies.

  19. Recent Progress in Multiparameter Measurement Based on Extrinsic Fiber-Optic Fabry-Perot Interferometers and Fiber Gratings

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    This paper presents a review of recent progress in simultaneous measurement of multiparameters including strain, temperature, vibration, transverse load, based on the combinations of extrinsic fiber-optic Fabry-Perot interferometers and fiber gratings.

  20. Intrinsic vs. extrinsic influences on life history expression: metabolism and parentally induced temperature influences on embryo development rate

    Science.gov (United States)

    Martin, Thomas E.; Ton, Riccardo; Nikilson, Alina

    2013-01-01

    Intrinsic processes are assumed to underlie life history expression and trade-offs, but extrinsic inputs are theorised to shift trait expression and mask trade-offs within species. Here, we explore application of this theory across species. We do this based on parentally induced embryo temperature as an extrinsic input, and mass-specific embryo metabolism as an intrinsic process, underlying embryonic development rate. We found that embryonic metabolism followed intrinsic allometry rules among 49 songbird species from temperate and tropical sites. Extrinsic inputs via parentally induced temperatures explained the majority of variation in development rates and masked a relationship with metabolism; metabolism explained a minor proportion of the variation in development rates among species, and only after accounting for temperature effects. We discuss evidence that temperature further obscures the expected interspecific trade-off between development rate and offspring quality. These results demonstrate the importance of considering extrinsic inputs to trait expression and trade-offs across species.

  1. The relationship between extrinsic motivation, home literacy, classroom instructional practices, and reading proficiency in second-grade Chinese children

    National Research Council Canada - National Science Library

    Yin-kum Law

    2008-01-01

      According to Wigfield (1997), children's reading motivation is multidimensional and extrinsic aspects of reading motivations include reading recognition, reading for grades, competition in reading, social reasons for reading...

  2. Differential influences of achievement approach goals and intrinsic/extrinsic motivation on help-seeking in e-learning

    National Research Council Canada - National Science Library

    Yan Yang; Li Cao

    2013-01-01

    ...’ help-seeking through intrinsic/extrinsic motivation. Path analyses were used to test two models of help-seeking among college students from four online educational psychology classes (N = 93...

  3. Long-term memory and response generalization in mushroom body extrinsic neurons in the honeybee Apis mellifera.

    Science.gov (United States)

    Haehnel, Melanie; Menzel, Randolf

    2012-02-01

    Honeybees learn to associate an odor with sucrose reward under conditions that allow the monitoring of neural activity by imaging Ca(2+) transients in morphologically identified neurons. Here we report such recordings from mushroom body extrinsic neurons - which belong to a recurrent tract connecting the output of the mushroom body with its input, potentially providing inhibitory feedback - and other extrinsic neurons. The neurons' responses to the learned odor and two novel control odors were measured 24 h after learning. We found that calcium responses to the learned odor and an odor that was strongly generalized with it were enhanced compared with responses to a weakly generalized control. Thus, the physiological responses measured in these extrinsic neurons accurately reflect what is observed in behavior. We conclude that the recorded recurrent neurons feed information back to the mushroom body about the features of learned odor stimuli. Other extrinsic neurons may signal information about learned odors to different brain regions.

  4. 不同反应基团接枝POE增韧PET研究%Study on Toughening of PET by POE Grafted by Different Reactive Monomer

    Institute of Scientific and Technical Information of China (English)

    刘世纯; 崔秀丽; 谭志勇

    2013-01-01

    Reactive monomers such as acrylic acid (AA),maleic anhydride (MAH)and glycidyl methacrylate (GMA)were grafted onto polyolefinic elastomer(POE) by melt blending to prepare POE-g-GMA,POE-g-MAH,POE-g-AA. The different reactive groups functionalized POE elastomers used as modifiers to toughen polyethylene terephthalate(PET) were investigated. Fourier transform infrared spectroscopy(FTIR) results show that these monomers were introduced onto POE. The results show that impact strength and compatibility are improved obviously in PET/POE-g-GMA blends than in PET/POE-g-AA and PET/POE-g-MAH. The melt flow rate of blends decrease obviously in PET/POE-g-GMA blends. POE-g-AA and POE-g-MAH are ineffective for toughening PET,but POE-g-GMA is effective for toughening PET.%采用熔融接枝法在聚烯烃弹性体(POE)上分别接枝三种不同的反应性单体马来酸酐(MAH)、丙烯酸(AA)、甲基丙烯酸环氧丙酯(GMA),制备了POE-g-GMA,POE-g-MAH,POE-g-AA,考察了三种不同反应基团接枝的POE对PET的增韧效果。采用傅立叶变换红外光谱(FTIR)证实三种反应单体成功接枝到POE分子链上。结果表明, PET/POE-g-GMA共混物的冲击强度、相容性明显高于PET/POE-g-AA与PET/POE-g-MAH共混物,熔体流动速率明显降低。POE-g-AA与POE-g-MAH不能有效增韧PET,而POE-g-GMA是PET的有效增韧剂。

  5. Associations among teacher-student interpersonal relationships and students’ intrinsic and extrinsic motivation and academic achievement: A cross cultural study

    OpenAIRE

    Chan, Dawn

    2016-01-01

    This cross-cultural study explored associations among teacher-student relationship, students’ intrinsic and extrinsic motivation, and students’ academic achievement in grade 5 and 6 students from Vancouver, Canada (n = 102) and Hong Kong, China (n = 207). Hong Kong students perceived their teachers to be more dissatisfied, strict, admonishing, and uncertain, while Vancouver students perceived their teachers to be more helpful and friendly. Students’ levels of intrinsic and extrinsic motivatio...

  6. Associations among teacher-student interpersonal relationships and students’ intrinsic and extrinsic motivation and academic achievement: A cross cultural study

    OpenAIRE

    Chan, Dawn

    2016-01-01

    This cross-cultural study explored associations among teacher-student relationship, students’ intrinsic and extrinsic motivation, and students’ academic achievement in grade 5 and 6 students from Vancouver, Canada (n = 102) and Hong Kong, China (n = 207). Hong Kong students perceived their teachers to be more dissatisfied, strict, admonishing, and uncertain, while Vancouver students perceived their teachers to be more helpful and friendly. Students’ levels of intrinsic and extrinsic motivatio...

  7. The Influence of Intrinsic and Extrinsic Rewards on Employee Results: An Empirical Analysis in Turkish Manufacturing Industry

    OpenAIRE

    Hatice Ozutku

    2012-01-01

    The study discussed in this article questions whether certain reward practices used by organizations are better than others when comparing the employee results based on TQM. We first examine reward systems and TQM relevant literature. After related literature review, reward practices have been handled in two groups as intrinsic rewards and extrinsic rewards. In the sample, which consists of 217 businesses that operate in Turkish manufacturing industry and apply TQM, intrinsic and extrinsic re...

  8. The Influence of Intrinsic and Extrinsic Rewards on Employee Results: An Empirical Analysis in Turkish Manufacturing Industry

    OpenAIRE

    Hatice Ozutku

    2012-01-01

    The study discussed in this article questions whether certain reward practices used by organizations are better than others when comparing the employee results based on TQM. We first examine reward systems and TQM relevant literature. After related literature review, reward practices have been handled in two groups as intrinsic rewards and extrinsic rewards. In the sample, which consists of 217 businesses that operate in Turkish manufacturing industry and apply TQM, intrinsic and extrinsic re...

  9. Extrinsic attributes that influence parents' purchase of chocolate milk for their children.

    Science.gov (United States)

    Li, Xiaomeng E; Lopetcharat, Kannapon; Drake, MaryAnne

    2014-07-01

    The consumption of milk is essential for children's heath; and flavored milk, especially chocolate milk, is often purchased to increase children's milk consumption. However, the sugar content of chocolate milk has raised health concerns. As such, it is important to understand chocolate milk extrinsic attributes that influence parents' purchase decisions when they are purchasing chocolate milk for their children. The objective of this study was to determine the key extrinsic attributes for parents when they purchase chocolate milk for their children. An online survey with a conjoint analysis design, emotions questions, and Kano questionnaire that focused on chocolate milk was conducted targeting parents. Three hundred and twelve parents participated in the survey. Parents reported positive emotions including good, good natured, happy, loving, and satisfied when purchasing chocolate milk for their kids. Three segments of parents were identified with subtle but distinct differences in their key preferences for chocolate milk attributes for their children. Type of sweetener was the primary driver of choice for purchasing chocolate milk for children followed by fat content. Among sweetener types, natural noncaloric/nonnutritive sweeteners or sucrose were preferred over artificial sweeteners, and reduced fat was preferred over full fat or skim milk. Kano results revealed that reduced fat and sugar with an all natural label and added vitamins, minerals, and protein were attractive to the majority of parents when purchasing chocolate milk for their kids. Understanding the driving extrinsic attributes for parents when they purchase chocolate milk for their children will assist manufacturers to target extrinsic attributes that are attractive to parents for chocolate milk. This study established that sweetener type and fat content are the primary extrinsic attributes affecting parents purchase decisions when choosing chocolate milk for their children. Different segments of

  10. In situ toughened SiC ceramics with Al-B-C additions and oxide-coated SiC platelet/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Cao, J. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley National Lab., CA (United States). Materials Sciences Div.

    1996-12-01

    This work aimed at fabrication and characterization of high toughness SiC ceramics through the applications of in situ toughening and SiC platelet reinforcement. The processing-microstructure-property relations of hot pressed SiC with Al, B, and C additions (designated as ABC-SiC) were investigated. Through a liquid phase sintering mechanism, dense SiC was obtained by hot pressing at a temperature as low as 1,700 C with 3 wt% Al, 0.6 wt% B, and 2 wt% C additions. These sintering aids also enhanced the {beta}-to-{alpha} (3C-to-4H) phase transformation, which promoted SiC grains to grow into plate-like shapes. Under optimal processing conditions, the microstructure exhibited high-aspect-ratio plate-shaped grains with a thin (< 1 nm) Al-containing amorphous grain boundary film. The mechanical properties of the toughened SiC and the composites were evaluated in comparison with a commercial Hexoloy SiC under identical test conditions. The C-curve behavior was examined using the strength-indentation load relationship and compared with that directly measured using precracked compact tension specimens. The in situ toughened ABC-SiC exhibited much improved flaw tolerance and a significantly rising R-curve behavior. A steady-state toughness in excess of 9 MPam{sup 1/2} was recorded for the ABC-SiC in comparison to a single valued toughness below 3 MPam{sup 1/2} for the Hexoloy. Toughening in the ABC-SiC was mainly attributed to grain bridging and subsequent pullout of the plate-shaped grains. The high toughness ABC-SiC exhibited a bend strength of 650 MPa with a Weibull modulus of 19; in comparison, the commercial SiC showed a bend strength of 400 MPa with a Weibull modulus of 6. Higher fracture toughness was also achieved by the reinforcement of SiC platelets, encapsulated with alumina, yttria, or silica, in a SiC matrix.

  11. Ceramic Technology Project database: September 1990 summary report. [SiC, SiN, whisker-reinforced SiN, ZrO-toughened aluminas, zirconias, joints

    Energy Technology Data Exchange (ETDEWEB)

    Keyes, B.L.P.

    1992-06-01

    Data generated within the Ceramic Technology Project (CTP) represent a valuable resource for both research and industry. The CTP database was created to provide easy access to this information in electronic and hardcopy forms by using a computerized database and by issuing periodic hardcopy reports on the database contents. This report is the sixth in a series of semiannual database summaries and covers recent additions to the database, including joined brazed specimen test data. It covers 1 SiC, 34 SiN, 10 whisker-reinforced SiN, 2 zirconia-toughened aluminas, 8 zirconias, and 34 joints.

  12. Highly toughened polypropylene/ethylene–propylene-diene monomer/zinc dimethacrylate ternary blends prepared via peroxide-induced dynamic vulcanization

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yukun, E-mail: cyk@scut.edu.cn [The Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640 (China); School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640 (China); Xu, Chuanhui [College of Material Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Cao, Liming [The Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640 (China); School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640 (China); Cao, Xiaodong [College of Material Science and Engineering, South China University of Technology, Guangzhou 510640 (China)

    2013-02-15

    Polypropylene (PP)/ethylene–propylene-diene monomer (EPDM)/zinc dimethacrylate (ZDMA) blends with remarkable toughness and extensibility were successfully prepared via peroxide dynamical vulcanization. A unique structure with the EPDM particles surrounded by a transition zone containing numerous polymerized ZDMA (PZDMA) nano-particles was observed for the first time by using transmission electron microscopy (TEM) examination, which contributed to the dramatically increase of Izod impact strength. Dynamic mechanical analysis (DMA) confirmed that the possible PZDMA graft products resulted from peroxide dynamical vulcanization improved the compatibility between EPDM and PP phases. The specific morphology of the PP/EPDM/ZDMA blends indicated that ZDMA can lead to size reduction and good distribution uniformity of the crosslinked rubber particles and the increase of adhesion between PP matrix and EPDM phases during deformation. The synergic effect of the increase in the effective volume of the EPDM phase, the improved compatibility and adhesion between EPDM and PP phases and the deformation of those fine rubber particles is believed to result in the remarkable high toughness and extensibility of the PP/EPDM/ZDMA blends. Particularly for the PP/EPDM ratio of 70/30, the PP/EPDM/ZDMA (70/30/9, w/w/w) ternary blends with the Izod impact strength nearly 2 times higher than PP/EPDM (70/30, w/w) binary blends and 15–20 times higher than PP are achieved; besides, the elongation at break of PP/EPDM/ZDMA ternary blends is 4–5 times higher than that of PP/EPDM binary blends. - Highlights: ► ZDMA largely toughen peroxide dynamically vulcanized PP/EPDM blend. ► PZDMA graft products improved the compatibility and adhesion between EPDM and PP. ► Size reduction and good distribution uniformity of crosslinked rubber particles.

  13. Polyamide 4,6 nanocomposites with and without the use of a maleated polyolefin elastomer as a toughener

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Fang-Chyou, E-mail: maxson@mail.cgu.edu.tw [Department of Chemical and Materials Engineering, Chang Gung University, Tao-Yuan 333, Taiwan (China); Deng, Tsung-Lin [Department of Chemical and Materials Engineering, Chang Gung University, Tao-Yuan 333, Taiwan (China)

    2011-02-15

    In this study, polyamide 4,6 (PA 4,6)-based nanocomposites were successfully prepared using a twin screw extruder. A commercial organo-montmorillonite (denoted as 30B) and a commercial maleated polyolefin elastomer (denoted as POEMA) served as the reinforcing filler and toughener, respectively. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results confirmed the nano-scaled dispersion of 30B in the composites. Nevertheless, the presence of POEMA slightly depreciated the dispersibility of 30B. Polarized light microscope (PLM) observations showed that the inclusions of 30B and POEMA led to the formation of diffused/broken PA 4,6 spherulites. Differential scanning calorimetry (DSC) results indicated that the addition of 30B retarded the crystallization of PA 4,6; the addition of POEMA led to a similar retardation effect on PA 4,6 crystallization. Interesting melting behaviors associated mainly with the crystal annealing of PA 4,6 upon heating were observed for the fast-cooled samples. The presence of POEMA was noted to hamper the annealing process of PA 4,6 crystals. The thermal stability enhancement of PA 4,6 in the presence of 30B was further raised to a higher extent when POEMA was included in the matrix. The rigidity, including the storage/Young's/flexural moduli, of PA 4,6 significantly increased after adding 30B. These properties, however, declined after the additional incorporation of POEMA. The PA 4,6/POEMA/30B nanocomposites basically displayed balanced impact strength between those of the neat PA 4,6 and PA 4,6/POEMA blends.

  14. Supertoughened Biobased Poly(lactic acid)-Epoxidized Natural Rubber Thermoplastic Vulcanizates: Fabrication, Co-continuous Phase Structure, Interfacial in Situ Compatibilization, and Toughening Mechanism.

    Science.gov (United States)

    Wang, Youhong; Chen, Kunling; Xu, Chuanhui; Chen, Yukun

    2015-09-10

    In the presence of dicumyl peroxide (DCP), biobased thermoplastic vulcanizates (TPVs) composed of poly(lactic acid) (PLA) and epoxidized natural rubber (ENR) were prepared through dynamic vulcanization. Interfacial in situ compatibilization between PLA and ENR phases was confirmed by Fourier transform infrared spectroscopy (FT-IR). A novel "sea-sea" co-continuous phase in the PLA/ENR TPVs was observed through scanning electron microscopy (SEM) and differed from the typical "sea-island" morphology that cross-linked rubber particles dispersed in plastic matrix. A sharp, brittle-ductile transition occurred with 40 wt % of ENR, showing a significantly improved impact strength of 47 kJ/m(2), nearly 15 times that of the neat PLA and 2.6 times that of the simple blend with the same PLA/ENR ratio. Gel permeation chromatography (GPC) and dynamic mechanical analysis (DMA) results suggested that a certain amount of DCP was consumed in the PLA phase, causing a slight cross-linking or branching of PLA molecules. the effects of various DCP contents on the impact property were investigated. The toughening mechanism under impact testing was researched, and the influence factors for toughening were discussed.

  15. SYNTHESIS OF A HYPERBRANCHED POLYETHER EPOXY THROUGH ONESTEP PROTON TRANSFER POLYMERIZATION AND ITS APPLICATION AS A TOUGHENER FOR EPOXY RESIN DGEBA

    Institute of Scientific and Technical Information of China (English)

    Jian-yong Lv; Yan Meng; Li-fan He; Xiao-yu Li; Hai-qiao Wang

    2012-01-01

    A novel liquid hyperbranched polyether epoxy (HBPEE) based on commercially available hydroquinone (HQ) and 1,1,1-trihydroxymethylpropane triglycidyl ether (TMPGE) was synthesized through an A2 + B3 one-step proton transfer polymerization.In order to improve the toughness,the synthesized HBPEE was mixed with diglycidyl ether of bisphenol A (DGEBA) in different ratios to form hybrids and cured with triethylenetetrarnine (TETA).Thermal and mechanical properties of the cured hybrids were evaluated.Results show that addition of HBPEE can improve the toughness of cured hybrids remarkably at < 20 wt% loading,without compromising the tensile strength.However,the glass transition temperature (Tg) of the cured hybrids decreases with increasing HBPEE content.Fracture surface images from scanning electron microscope show oriented fibrils in hybrids containing HBPEE.The formation and orientation of the fibrils can absorb energy under impact and lead to an improvement of toughness.Furthermore,based on the morphology of fractured surfaces and the single Tg in each hybrid,no sign of phase separation was found in the cured hybrid systems.As a result,the toughening mechanism could be explained by in situ homogeneous toughening mechanism rather than phase separation mechanism.

  16. Electrophysiological and histological changes in extrinsic muscles proximal to post burn contractures of hand.

    Science.gov (United States)

    Bhattacharya, V; Purwar, Shammi; Joshi, D; Kumar, M; Mandal, S; Chaudhuri, G R; Bhattacharya, S

    2011-06-01

    Burn scar hand contractures of variable degree are frequently encountered. Although the forearm is apparently spared, it was clinically observed that there was disuse atrophy in the unburnt extrinsic forearm muscles. Usually the clinicians do not give much importance to this fact. The girth at the midforearm was significantly reduced as compared to normal side. The flexion of the hand joints are governed by two components (a) intrinsic and (b) extrinsic muscles. The intrinsic muscles are directly involved in the contracted tissue. Therefore it was thought essential to evaluate the extrinsic group of muscles for their contribution in the final functional recovery following corrective surgery. Thirty patients having unilateral post thermal burn contracture sparing forearm were studied. A detailed clinical evaluation was made including grade of contracture and reduction in the forearm girth. The forearm unburnt muscles were evaluated by preoperative electrophysiological studies. Intraoperative biopsies were taken from these muscles for histopathological examination. On histopathological examination, there were significant abnormal changes in the form of muscle fiber atrophy, fibrolipomatous tissue replacement of atrophic muscle fibers and sarcolemmal changes. These changes were directly proportional to the severity of contractures. The electrophysiological studies showed proportionate changes in the form of reduction in amplitude, duration and interference. This study suggests that if these changes are mild and in reversible stage, they will favourably affect the functional recovery following surgery. However if these changes are of severe grade and irreversible, in spite of adequate surgery, splinting and physiotherapy, the functional recovery may not be complete. Copyright © 2011 Elsevier Ltd and ISBI. All rights reserved.

  17. Finger joint motion generated by individual extrinsic muscles: A cadaveric study

    Directory of Open Access Journals (Sweden)

    Li Zong-Ming

    2008-07-01

    Full Text Available Abstract Background Our understanding of finger functionality associated with the specific muscle is mostly based on the functional anatomy, and the exact motion effect associated with an individual muscle is still unknown. The purpose of this study was to examine phalangeal joints motion of the index finger generated by each extrinsic muscle. Methods Ten (6 female and 4 male fresh-frozen cadaveric hands (age 55.2 ± 5.6 years were minimally dissected to establish baseball sutures at the musculotendinous junctions of the index finger extrinsic muscles. Each tendon was loaded to 10% of its force potential and the motion generated at the metacarpophalangeal (MCP, proximal interphalangeal (PIP, and distal interphalangeal (DIP joints was simultaneously recorded using a marker-based motion capture system. Results The flexor digitorum profundus (FDP generated average flexion of 19.7, 41.8, and 29.4 degrees at the MCP, PIP, and DIP joints, respectively. The flexor digitorum superficialis (FDS generated average flexion of 24.8 and 47.9 degrees at the MCP and PIP joints, respectively, and no motion at the DIP joints. The extensor digitorum communis (EDC and extensor indicis proprius (EIP generated average extension of 18.3, 15.2, 4.0 degrees and 15.4, 13.2, 3.7 degrees at the MCP, PIP and DIP joints, respectively. The FDP generated simultaneous motion at the PIP and DIP joints. However, the motion generated by the FDP and FDS, at the MCP joint lagged the motion generated at the PIP joint. The EDC and EIP generated simultaneous motion at the MCP and PIP joints. Conclusion The results of this study provide novel insights into the kinematic role of individual extrinsic muscles.

  18. Involvement of eicosanoids and surfactant protein D in extrinsic allergic alveolitis.

    Science.gov (United States)

    Higashi, A; Higashi, N; Tsuburai, T; Takeuchi, Y; Taniguchi, M; Mita, H; Saito, A; Takatori, K; Arimura, K; Akiyama, K

    2005-12-01

    The pathophysiology of extrinsic allergic alveolitis (EAA) involves oxidative lung damage as well as interstitial and alveolar inflammation. Macrophages and mast cells are inflammatory components of EAA that produce both leukotrienes (LTs) and prostaglandin D2 (PGD2). In addition, PGD2 is also produced by the free-radical-catalysed peroxidation of arachidonic acid during oxidative stress. Urinary 8-iso prostaglandin F2alpha (8-isoPGF2alpha) and serum surfactant protein D (SP-D) are considered appropriate biomarkers of oxidative stress and interstitial lung disease activity, respectively. The present study aimed to assess the association of these biomarkers with the pathophysiology of EAA. Two cases of acute EAA caused by the inhalation of fungi spores were reported. Eight asthmatic patients and six healthy control subjects were also enrolled in the current study. The serum SP-D and urinary eicosanoid (LTE4, PGD2 metabolite (9alpha,11betaPGF2), 8-isoPGF2alpha) concentrations markedly increased during the acute exacerbation phase. These concentrations decreased following corticosteroid therapy in the EAA patients. There was a significant correlation between serum SP-D and urinary 9alpha,11betaPGF2 concentrations in the EAA patients. In conclusion, although the present study proposes that serum surfactant protein-D and urinary eicosanoids are new biomarkers involved in the various immunological responses in extrinsic allergic alveolitis, further large-scale studies are needed to investigate the role of these compounds, not just as biomarkers, but also as biological potentiators of extrinsic allergic alveolitis.

  19. Providing Extrinsic Reward for Test Performance Undermines Long-Term Memory Acquisition

    Directory of Open Access Journals (Sweden)

    Christof eKuhbandner

    2016-02-01

    Full Text Available Based on numerous studies showing that testing studied material can improve long-term retention more than restudying the same material, it is often suggested that the number of tests in education should be increased to enhance knowledge acquisition. However, testing in real-life educational settings often entails a high degree of extrinsic motivation of learners due to the common practice of placing important consequences on the outcome of a test. Such an effect on the motivation of learners may undermine the beneficial effects of testing on long-term memory because it has been shown that extrinsic motivation can reduce the quality of learning. To examine this issue, participants learned foreign language vocabulary words, followed by an immediate test in which one third of the words were tested and one third restudied. To manipulate extrinsic motivation during immediate testing, participants received either monetary reward contingent on test performance or no reward. After one week, memory for all words was tested. In the immediate test, reward reduced correct recall and increased commission errors, indicating that reward reduced the number of items that can benefit from successful retrieval. The results in the delayed test revealed that reward additionally reduced the gain received from successful retrieval because memory for initially successfully retrieved words was lower in the reward condition. However, testing was still more effective than restudying under reward conditions because reward undermined long-term memory for concurrently restudied material as well. These findings indicate that providing performance-contingent reward in a test can undermine long-term knowledge acquisition.

  20. Providing Extrinsic Reward for Test Performance Undermines Long-Term Memory Acquisition.

    Science.gov (United States)

    Kuhbandner, Christof; Aslan, Alp; Emmerdinger, Kathrin; Murayama, Kou

    2016-01-01

    Based on numerous studies showing that testing studied material can improve long-term retention more than restudying the same material, it is often suggested that the number of tests in education should be increased to enhance knowledge acquisition. However, testing in real-life educational settings often entails a high degree of extrinsic motivation of learners due to the common practice of placing important consequences on the outcome of a test. Such an effect on the motivation of learners may undermine the beneficial effects of testing on long-term memory because it has been shown that extrinsic motivation can reduce the quality of learning. To examine this issue, participants learned foreign language vocabulary words, followed by an immediate test in which one-third of the words were tested and one-third restudied. To manipulate extrinsic motivation during immediate testing, participants received either monetary reward contingent on test performance or no reward. After 1 week, memory for all words was tested. In the immediate test, reward reduced correct recall and increased commission errors, indicating that reward reduced the number of items that can benefit from successful retrieval. The results in the delayed test revealed that reward additionally reduced the gain received from successful retrieval because memory for initially successfully retrieved words was lower in the reward condition. However, testing was still more effective than restudying under reward conditions because reward undermined long-term memory for concurrently restudied material as well. These findings indicate that providing performance-contingent reward in a test can undermine long-term knowledge acquisition.

  1. Providing Extrinsic Reward for Test Performance Undermines Long-Term Memory Acquisition

    Science.gov (United States)

    Kuhbandner, Christof; Aslan, Alp; Emmerdinger, Kathrin; Murayama, Kou

    2016-01-01

    Based on numerous studies showing that testing studied material can improve long-term retention more than restudying the same material, it is often suggested that the number of tests in education should be increased to enhance knowledge acquisition. However, testing in real-life educational settings often entails a high degree of extrinsic motivation of learners due to the common practice of placing important consequences on the outcome of a test. Such an effect on the motivation of learners may undermine the beneficial effects of testing on long-term memory because it has been shown that extrinsic motivation can reduce the quality of learning. To examine this issue, participants learned foreign language vocabulary words, followed by an immediate test in which one-third of the words were tested and one-third restudied. To manipulate extrinsic motivation during immediate testing, participants received either monetary reward contingent on test performance or no reward. After 1 week, memory for all words was tested. In the immediate test, reward reduced correct recall and increased commission errors, indicating that reward reduced the number of items that can benefit from successful retrieval. The results in the delayed test revealed that reward additionally reduced the gain received from successful retrieval because memory for initially successfully retrieved words was lower in the reward condition. However, testing was still more effective than restudying under reward conditions because reward undermined long-term memory for concurrently restudied material as well. These findings indicate that providing performance–contingent reward in a test can undermine long-term knowledge acquisition. PMID:26869978

  2. Combined model of intrinsic and extrinsic variability for computational network design with application to synthetic biology.

    Directory of Open Access Journals (Sweden)

    Tina Toni

    Full Text Available Biological systems are inherently variable, with their dynamics influenced by intrinsic and extrinsic sources. These systems are often only partially characterized, with large uncertainties about specific sources of extrinsic variability and biochemical properties. Moreover, it is not yet well understood how different sources of variability combine and affect biological systems in concert. To successfully design biomedical therapies or synthetic circuits with robust performance, it is crucial to account for uncertainty and effects of variability. Here we introduce an efficient modeling and simulation framework to study systems that are simultaneously subject to multiple sources of variability, and apply it to make design decisions on small genetic networks that play a role of basic design elements of synthetic circuits. Specifically, the framework was used to explore the effect of transcriptional and post-transcriptional autoregulation on fluctuations in protein expression in simple genetic networks. We found that autoregulation could either suppress or increase the output variability, depending on specific noise sources and network parameters. We showed that transcriptional autoregulation was more successful than post-transcriptional in suppressing variability across a wide range of intrinsic and extrinsic magnitudes and sources. We derived the following design principles to guide the design of circuits that best suppress variability: (i high protein cooperativity and low miRNA cooperativity, (ii imperfect complementarity between miRNA and mRNA was preferred to perfect complementarity, and (iii correlated expression of mRNA and miRNA--for example, on the same transcript--was best for suppression of protein variability. Results further showed that correlations in kinetic parameters between cells affected the ability to suppress variability, and that variability in transient states did not necessarily follow the same principles as variability in

  3. 输气管道减阻内涂层与减阻剂应用现状及效益分析%Application and economic benefits of internal drag-reduction coating and DRA in gas pipeline

    Institute of Scientific and Technical Information of China (English)

    张兴水; 曹杰

    2013-01-01

    The paper reviews the advantages and disadvantages of internal drag-reduction coating and DRA used to improve pipeline gas transmission as well as their economic benefit and prospects.The internal drag-reduction coating has been used as a proved technique in long-distance gas pipelines at home and abroad with significant economic benefit,but its application is restricted by some handicaps such as large one-off investment,complex procedures,harsh operating conditions and uncertainty of coating service life.The use of DRA has won great favor due to its simple technology and wide applicability.However,as a technique which would be used in the future,it is still in the phase of research and development.(2 Figures,16 References)%综述了提高天然气管输效率的内涂层法和减阻剂法的经济效益、优势、不足以及应用前景.内涂层法已在国内外长输天然气管道中成熟应用,经济效益明显,但存在一次性投资较大、施工程序复杂、施工条件苛刻,涂层寿命尚不确定等问题;减阻剂法因加注工艺简单、适用性广而备受青睐,但作为管道储备技术尚处于开发研究阶段.(图2,参16)

  4. Extrinsic reference frames modify the neural substrates of object-location representations.

    Science.gov (United States)

    Chan, Edgar; Baumann, Oliver; Bellgrove, Mark A; Mattingley, Jason B

    2013-04-01

    The ability to form spatial representations of object locations is an important component of successful spatial navigation. Evidence from behavioral studies suggests that environmental features that have a salient coordinate axis (e.g., a rectangular building or a geometrical room) may provide a reference frame for the encoding of object-location information. Here we used functional magnetic resonance imaging (fMRI) to determine the brain networks engaged when object-location representations are stored with respect to an extrinsic reference frame. Participants learned the layout of an object array in an active, virtual-navigation paradigm. A square mat positioned on the floor of the virtual arena acted as the extrinsic reference frame. Knowledge of the spatial arrangement of the object array was probed while participants underwent fMRI, using a spatial judgment task that required them to imagine orientations of the learned array that were either aligned or misaligned with the geometry of the mat. Consistent with previous findings, participants responded faster and were more accurate when the imagined orientation was aligned, as opposed to misaligned, with the extrinsic reference frame. Analysis of the fMRI data revealed important differences in brain activity between the two conditions. Significantly greater activity was observed in the aligned condition compared with the misaligned condition across a bilateral network of brain areas that included the inferior occipital gyri, inferior and middle temporal gyri, and fusiform gyri. By contrast, activity in the misaligned condition was significantly greater than in the aligned condition in bilateral dorsolateral prefrontal and anterior cingulate cortex, and in the right anterior prefrontal and anterior insular cortex. These results suggest that retrieval of spatial locations that are aligned with an extrinsic reference frame involve direct access to detailed and accurate representations within the ventral visual

  5. Extrinsic coefficient charcterisation of PZT ceramics near the morphotropic phase boundary

    Directory of Open Access Journals (Sweden)

    Albareda, A.

    2006-06-01

    Full Text Available PZT ceramics with high piezoelectric coefficients have high extrinsic contributions. This extrinsic behaviour, which is related to the domain wall movement, produces high non-linear effects that are sometimes inconvenient, for example when it increases the losses in power devices. The relation between extrinsic behaviour and non-linearities could be used to provide a good extrinsic characterization of materials in order to optimise the piezoelectric devices. In all cases the physical explanation of the behaviour is sought. The aim of this work is to study the dependence of the linear and non-linear dielectric, piezoelectric and mechanical coefficients on the Ti fraction in PZT ceramic compositions near the morphotropic phase boundary (MPB. The dependence of these coefficients on the defect concentration is also analysed. Hard ceramics belonging to Ferroperm Piezoceramics, with two different acceptor dopant levels, high and low, have been measured.

    Las cerámicas PZT con coeficientes piezoeléctricos elevados poseen contribuciones extrínsecas grandes. Este comportamiento extrínseco, relacionado con el movimiento de las paredes de los dominios, comporta efectos no lineales grandes que no siempre son deseables, por ejemplo, al incrementar las pérdidas de los dispositivos piezoeléctricos. Esta correspondencia entre efectos extrínsecos y no linealidades puede ser utilizada para caracterizar las cerámicas con el fin de optimizar sus propiedades piezoeléctricas. En todos los casos se busca una interpretación física de los resultados obtenidos. El objetivo de este trabajo es el estudio de la dependencia de los coeficientes lineales y no lineales dieléctricos, piezoeléctricos y elásticos con la fracción de Ti en cerámicas PZT con composiciones de Zr-Ti cerca de la transición de fase morfotrópica (MPB. También se analiza la dependencia de estos coeficientes con la concentración de impurezas, utilizando para ello cerámicas de

  6. New occupational and environmental causes of asthma and extrinsic allergic alveolitis.

    Science.gov (United States)

    Fishwick, David

    2012-12-01

    Asthma and extrinsic allergic alveolitis (EAA) remain prevalent respiratory diseases and the cause of a significant disease burden. This article reviews the recent occupational and environmental causes described for these conditions. Even over the limited time spam addressed by this article, novel agents and new data relating to already suggested causes have been described. Various types of work tasks or exposures are described that appear to cause both asthma and EAA. Isocyanates, the best example of dual potential to cause asthma and EAA are discussed, as is the new understanding of the role metal-working fluids play when causing respiratory diseases. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

  7. Statistical analysis of intrinsic and extrinsic coupling losses for step-index polymer optical fibers.

    Science.gov (United States)

    Werzinger, Stefan; Bunge, Christian-Alexander

    2015-08-24

    The intrinsic and extrinsic coupling losses of step-index polymer optical fibers are statistically examined by Monte Carlo simulations. In contrast to most existing models that linearly scale individual losses, a comprehensive analytic coupling loss model is used that also considers the interdependencies between mismatches in numerical aperture and core diameter, as well as radial and longitudinal offsets. As a typical example, the coupling losses of A4a.2 step-index multimode fibers are analyzed for an equilibrium mode distribution. The results show considerably less conservative coupling loss estimations than with traditional models, improving link power budgeting.

  8. Intrinsic and Extrinsic Motivation Among Adolescent Ten-Pin Bowlers in Kuala Lumpur, Malaysia

    OpenAIRE

    Teo Eng-Wah; Khoo Selina; Wong Rebecca; Wee Eng-Hoe; Lim Boon-Hooi; Rengasamy Shabesan Sit

    2015-01-01

    Motivation has long been associated with sports engagement. However, to date no research has been performed to understand the domain of motivation among ten-pin bowlers. The purpose of this study was to investigate different types of motivation (i.e., intrinsic vs. extrinsic) based on self-determination theory from the perspective of gender and the bowler type (competitive vs. casual). A total of 240 bowlers (104 male, 136 female; 152 competitive, 88 casual) with a mean age of 16.61 ± 0.78 ye...

  9. Extrinsic spin Hall effect induced by resonant skew scattering in graphene.

    Science.gov (United States)

    Ferreira, Aires; Rappoport, Tatiana G; Cazalilla, Miguel A; Castro Neto, A H

    2014-02-14

    We show that the extrinsic spin Hall effect can be engineered in monolayer graphene by decoration with small doses of adatoms, molecules, or nanoparticles originating local spin-orbit perturbations. The analysis of the single impurity scattering problem shows that intrinsic and Rashba spin-orbit local couplings enhance the spin Hall effect via skew scattering of charge carriers in the resonant regime. The solution of the transport equations for a random ensemble of spin-orbit impurities reveals that giant spin Hall currents are within the reach of the current state of the art in device fabrication. The spin Hall effect is robust with respect to thermal fluctuations and disorder averaging.

  10. Intrinsic and extrinsic motivation as predictors of work effort: the moderating role of achievement goals.

    Science.gov (United States)

    Dysvik, Anders; Kuvaas, Bård

    2013-09-01

    This research explored the roles of intrinsic motivation (IM) and extrinsic motivation (EM) and the 2 × 2 model of achievement goals as predictors of increased work effort (WE). A cross-lagged field study was conducted among 1,441 employees from three large Norwegian service organizations across a 10-month time span. The results showed that the relationship between IM and increased WE was more positive for employees with high levels of mastery-approach goals. This observation suggests that having congruent goals may accentuate the positive relationship between IM and WE. © 2012 The British Psychological Society.

  11. The impact of intrinsic and extrinsic factors on the job satisfaction of dentists.

    Science.gov (United States)

    Goetz, K; Campbell, S M; Broge, B; Dörfer, C E; Brodowski, M; Szecsenyi, J

    2012-10-01

    The Two-Factor Theory of job satisfaction distinguishes between intrinsic-motivation (i.e. recognition, responsibility) and extrinsic-hygiene (i.e. job security, salary, working conditions) factors. The presence of intrinsic-motivation facilitates higher satisfaction and performance, whereas the absences of extrinsic factors help mitigate against dissatisfaction. The consideration of these factors and their impact on dentists' job satisfaction is essential for the recruitment and retention of dentists. The objective of the study is to assess the level of job satisfaction of German dentists and the factors that are associated with it. This cross-sectional study was based on a job satisfaction survey. Data were collected from 147 dentists working in 106 dental practices. Job satisfaction was measured with the 10-item Warr-Cook-Wall job satisfaction scale. Organizational characteristics were measured with two items. Linear regression analyses were performed in which each of the nine items of the job satisfaction scale (excluding overall satisfaction) were handled as dependent variables. A stepwise linear regression analysis was performed with overall job satisfaction as the dependent outcome variable, the nine items of job satisfaction and the two items of organizational characteristics controlled for age and gender as predictors. The response rate was 95.0%. Dentists were satisfied with 'freedom of working method' and mostly dissatisfied with their 'income'. Both variables are extrinsic factors. The regression analyses identified five items that were significantly associated with each item of the job satisfaction scale: 'age', 'mean weekly working time', 'period in the practice', 'number of dentist's assistant' and 'working atmosphere'. Within the stepwise linear regression analysis the intrinsic factor 'opportunity to use abilities' (β = 0.687) showed the highest score of explained variance (R(2) = 0.468) regarding overall job satisfaction. With respect to the Two

  12. Intrinsic and Extrinsic Motivation Among Adolescent Ten-Pin Bowlers in Kuala Lumpur, Malaysia

    OpenAIRE

    Teo Eng-Wah; Khoo Selina; Wong Rebecca; Wee Eng-Hoe; Lim Boon-Hooi; Rengasamy Shabesan Sit

    2015-01-01

    Motivation has long been associated with sports engagement. However, to date no research has been performed to understand the domain of motivation among ten-pin bowlers. The purpose of this study was to investigate different types of motivation (i.e., intrinsic vs. extrinsic) based on self-determination theory from the perspective of gender and the bowler type (competitive vs. casual). A total of 240 bowlers (104 male, 136 female; 152 competitive, 88 casual) with a mean age of 16.61 ± 0.78 ye...

  13. Compensation of home health, public health, and hospital nurses. Extrinsic and intrinsic rewards.

    Science.gov (United States)

    Hughes, K K; Marcantonio, R J

    1991-11-01

    Despite the proliferation of home health agencies and increased numbers of nurses working in these settings, little is known about home health nurses or how they might differ from their public health and hospital counterparts. The authors discuss differences in monetary compensation and skill usage, as well as the relationship between compensation and retention, among hospital, home health, and public health staff nurses. The results show that these nurses receive different intrinsic and extrinsic rewards and that their reasons for remaining with their employers are similar, yet unique. Implications for nurse administrators and educators are discussed, along with recommendations for further research.

  14. Cell-extrinsic consequences of epithelial stress: activation of protumorigenic tissue phenotypes.

    Science.gov (United States)

    Fordyce, Colleen A; Patten, Kelley T; Fessenden, Tim B; DeFilippis, RosaAnna; Hwang, E Shelley; Zhao, Jianxin; Tlsty, Thea D

    2012-12-07

    Tumors are characterized by alterations in the epithelial and stromal compartments, which both contribute to tumor promotion. However, where, when, and how the tumor stroma develops is still poorly understood. We previously demonstrated that DNA damage or telomere malfunction induces an activin A-dependent epithelial stress response that activates cell-intrinsic and cell-extrinsic consequences in mortal, nontumorigenic human mammary epithelial cells (HMECs and vHMECs). Here we show that this epithelial stress response also induces protumorigenic phenotypes in neighboring primary fibroblasts, recapitulating many of the characteristics associated with formation of the tumor stroma (for example, desmoplasia). The contribution of extrinsic and intrinsic DNA damage to acquisition of desmoplastic phenotypes was investigated in primary human mammary fibroblasts (HMFs) co-cultured with vHMECs with telomere malfunction (TRF2-vHMEC) or in HMFs directly treated with DNA-damaging agents, respectively. Fibroblast reprogramming was assessed by monitoring increases in levels of selected protumorigenic molecules with quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and immunocytochemistry. Dependence of the induced phenotypes on activin A was evaluated by addition of exogenous activin A or activin A silencing. In vitro findings were validated in vivo, in preinvasive ductal carcinoma in situ (DCIS) lesions by using immunohistochemistry and telomere-specific fluorescent in situ hybridization. HMFs either cocultured with TRF2-vHMEC or directly exposed to exogenous activin A or PGE2 show increased expression of cytokines and growth factors, deposition of extracellular matrix (ECM) proteins, and a shift toward aerobic glycolysis. In turn, these "activated" fibroblasts secrete factors that promote epithelial cell motility. Interestingly, cell-intrinsic DNA damage in HMFs induces some, but not all, of the molecules induced as a consequence of cell-extrinsic DNA

  15. Analyzing the microfoundations of human violence in the DRC - intrinsic and extrinsic rewards and the prediction of appetitive aggression.

    Science.gov (United States)

    Haer, Roos; Banholzer, Lilli; Elbert, Thomas; Weierstall, Roland

    2013-05-17

    Civil wars are characterized by intense forms of violence, such as torture, maiming and rape. Political scientists suggest that this form of political violence is fostered through the provision of particular intrinsic and extrinsic rewards to combatants. In the field of psychology, the perpetration of this kind of cruelty is observed to be positively linked to appetitive aggression. Over time, combatants start to enjoy the fights and even the perpetration of atrocities. In this study, we examine how receiving rewards (intrinsic versus extrinsic) influence the level of appetitive aggression exhibited by former combatants. We surveyed 95 former combatants in the eastern provinces of the Democratic Republic of the Congo. Linear regression analyses reveal that intrinsic as well as extrinsic rewards are linked to the former combatants' Appetitive Aggression score. However, this relationship is partly determined by the way in which combatants are recruited: While abducted combatants seem to react more strongly to extrinsic rewards, the score of those that joined voluntarily is primarily determined by intrinsic rewards. We conclude that receiving rewards influence the level of appetitive aggression. However, which type of rewards (intrinsic versus extrinsic) is of most importance is determined by the way combatants are recruited.

  16. A conformal field theory of extrinsic geometry of 2-d surfaces

    CERN Document Server

    Viswanathan, K S; Viswanathan, K S; Parthasarathy, R

    1994-01-01

    In the description of the extrinsic geometry of the string world sheet regarded as a conformal immersion of a 2-d surface in R^3, it was previously shown that, restricting to surfaces with h\\surd{g}\\ =\\ 1, where h is the mean scalar curvature and g is the determinant of the induced metric on the surface, leads to Virasaro symmetry. An explicit form of the effective action on such surfaces is constructed in this article which is the extrinsic curvature analog of the WZNW action. This action turns out to be the gauge invariant combination of the actions encountered in 2-d intrinsic gravity theory in light-cone gauge and the geometric action appearing in the quantization of the Virasaro group. This action, besides exhibiting Virasaro symmetry in z-sector, has SL(2,C) conserved currents in the \\bar{z}-sector. This allows us to quantize this theory in the \\bar{z}-sector along the lines of the WZNW model. The quantum theory on h\\surd{g}\\ =\\ 1 surfaces in R^3 is shown to be in the same universality class as the intr...

  17. The determination of the intrinsic and extrinsic parameters of virtual camera based on OpenGL

    Science.gov (United States)

    Li, Suqi; Zhang, Guangjun; Wei, Zhenzhong

    2006-11-01

    OpenGL is the international standard of 3D image. The 3D image generation by OpenGL is similar to the shoot by camera. This paper focuses on the application of OpenGL to computer vision, the OpenGL 3D image is regarded as virtual camera image. Firstly, the imaging mechanism of OpenGL has been analyzed in view of perspective projection transformation of computer vision camera. Then, the relationship between intrinsic and extrinsic parameters of camera and function parameters in OpenGL has been analysed, the transformation formulas have been deduced. Thereout the computer vision simulation has been realized. According to the comparison between the actual CCD camera images and virtual camera images(the parameters of actual camera are the same as virtual camera's) and the experiment results of stereo vision 3D reconstruction simulation, the effectiveness of the method with which the intrinsic and extrinsic parameters of virtual camera based on OpenGL are determined has been verified.

  18. Lineage extrinsic and intrinsic control of immunoregulatory cell numbers by SHIP.

    Science.gov (United States)

    Collazo, Michelle M; Paraiso, Kim H T; Park, Mi-Young; Hazen, Amy L; Kerr, William G

    2012-07-01

    We previously showed that germline or induced SHIP deficiency expands immuno-regulatory cell numbers in T lymphoid and myeloid lineages. We postulated these increases could be interrelated. Here, we show that myeloid-specific ablation of SHIP leads to the expansion of both myeloid-derived suppressor cell (MDSC) and regulatory T (Treg) cell numbers, indicating SHIP-dependent control of Treg-cell numbers by a myeloid cell type. Conversely, T-lineage specific ablation of SHIP leads to expansion of Treg-cell numbers, but not expansion of the MDSC compartment, indicating SHIP also has a lineage intrinsic role in limiting Treg-cell numbers. However, the SHIP-deficient myeloid cell that promotes MDSC and Treg-cell expansion is not an MDSC as they lack SHIP protein expression. Thus, regulation of MDSC numbers in vivo must be controlled in a cell-extrinsic fashion by another myeloid cell type. We had previously shown that G-CSF levels are profoundly increased in SHIP(-/-) mice, suggesting this myelopoietic growth factor could promote MDSC expansion in a cell-extrinsic fashion. Consistent with this hypothesis, we find that G-CSF is required for expansion of the MDSC splenic compartment in mice rendered SHIP-deficient as adults. Thus, SHIP controls MDSC numbers, in part, by limiting production of the myelopoietic growth factor G-CSF.

  19. Extrinsic feedback and management of low back pain: A critical review of the literature.

    Science.gov (United States)

    Ribeiro, Daniel Cury; Sole, Gisela; Abbott, J Haxby; Milosavljevic, Stephan

    2011-06-01

    Effective intervention for low back pain (LBP) can include feedback in one form or other. Although extrinsic feedback (EF) can be provided in a number of ways, most research has not considered how different EF characteristics (e.g. timing and content) influence treatment outcomes. A systematic search related to feedback and LBP was performed on relevant electronic databases. This narrative review aims to describe the forms of feedback provision in the literature regarding management of LBP, and to discuss these in light of previously recommended principles for the use of extrinsic feedback. The present review found support for the provision of EF that focuses on content characteristics including program feedback, summary results feedback, and external focus of attention. Temporal characteristics should enhance the use of intermittent or self-selected feedback. The literature does not support the provision of concurrent or constant EF. As much of the literature related to EF in the management of LBP has not considered content and timing characteristics we have identified future research directions that will clarify the use of content and timing characteristics of EF relative to the management of LBP.

  20. Characterizing Facial Skin Ageing in Humans: Disentangling Extrinsic from Intrinsic Biological Phenomena

    Directory of Open Access Journals (Sweden)

    Carina Trojahn

    2015-01-01

    Full Text Available Facial skin ageing is caused by intrinsic and extrinsic mechanisms. Intrinsic ageing is highly related to chronological age. Age related skin changes can be measured using clinical and biophysical methods. The aim of this study was to evaluate whether and how clinical characteristics and biophysical parameters are associated with each other with and without adjustment for chronological age. Twenty-four female subjects of three age groups were enrolled. Clinical assessments (global facial skin ageing, wrinkling, and sagging, and biophysical measurements (roughness, colour, skin elasticity, and barrier function were conducted at both upper cheeks. Pearson’s correlations and linear regression models adjusted for age were calculated. Most of the measured parameters were correlated with chronological age (e.g., association with wrinkle score, r=0.901 and with each other (e.g., residual skin deformation and wrinkle score, r=0.606. After statistical adjustment for age, only few associations remained (e.g., mean roughness (Rz and luminance (L*,  β=-0.507, R2=0.377. Chronological age as surrogate marker for intrinsic ageing has the most important influence on most facial skin ageing signs. Changes in skin elasticity, wrinkling, sagging, and yellowness seem to be caused by additional extrinsic ageing.