WorldWideScience

Sample records for reverse ordering mechanisms

  1. Mechanically clamped PZT ceramics investigated by First-order reversal curves diagram

    Directory of Open Access Journals (Sweden)

    Laurentiu Stoleriu

    2010-09-01

    Full Text Available The First Order Reversal Curves (FORC diagrams method was developed for characterizing the switching properties of ferroelectrics. In the present paper, the FORC method was applied for hard Pb(Zr,TiO3 ceramics with symmetric and asymmetric clamping. An ideal high-oriented single-crystalline ferroelectric with rectangular P(E loop would be characterised by a delta-function FORC distribution, while real ferroelectrics and mostly the polycrystalline ceramics show dispersed FORC distributions. All the investigated ceramics show FORC distributions with non-Gaussian shape, slightly elongated along the coercitive axis, meaning a high dispersion of the energy barriers separating the two bi-stable polarizations ±P. The degree of dispersion is enhanced by clamping. The maximum FORC coercivity is located at ~ (1.9-2 MV/m for all the hard ceramics. The FORC cycling experiment causes the reversal of the initial poling and result in a positive/negative bias on the FORC diagrams. According to the observed features, it results that FORC coercivity is more related to the nature of the material, while the bias field is more sensitive to the electrical and mechanical boundary conditions in which the ferroelectric ceramics evolves while switching.

  2. Anomaly indicators for time-reversal symmetric topological orders

    CERN Document Server

    Wang, Chenjie

    2016-01-01

    Some time-reversal symmetric topological orders are anomalous in that they cannot be realized in strictly two-dimensions without breaking time reversal symmetry; instead, they can only be realized on the surface of certain three-dimensional systems. We propose two quantities, which we call {\\it anomaly indicators}, that can detect if a time-reversal symmetric topological order is anomalous in this sense. Both anomaly indicators are expressed in terms of the quantum dimensions, topological spins, and time-reversal properties of the anyons in the given topological order. The first indicator, $\\eta_2$, applies to bosonic systems while the second indicator, $\\eta_f$, applies to fermionic systems in the DIII class. We conjecture that $\\eta_2$, together with a previously known indicator $\\eta_1$, can detect the two known $\\mathbb Z_2$ anomalies in the bosonic case, while $\\eta_f$ can detect the $\\mathbb Z_{16}$ anomaly in the fermionic case.

  3. Mechanism of reverse-offset printing

    Science.gov (United States)

    Choi, Young-Man; Lee, Eonseok; Lee, Taik-Min

    2015-07-01

    We propose a mechanism for reverse-offset printing based on a mathematical model. In reverse-offset printing, high resolution is achieved by patterning a coated, thin ink film with an intaglio-patterned cliché. By using the relationships among the ink blanket adhesion strength, the ink cliché adhesion strength, and the ink cohesion strength, a criterion for successful patterning is derived. We found that there is a printing window in the ink blanket adhesion strength that depends on the shear strength of the ink film and the dimensions of the pattern. The printing window diminishes as the line width decreases, resulting in a minimum printable line width. The proposed mechanism was verified by printing patterns with various shapes and dimensions.

  4. First order reversal curves diagrams for describing ferroelectric switching characteristics

    Directory of Open Access Journals (Sweden)

    Liliana Mitoseriu

    2009-06-01

    Full Text Available First Order Reversal Curves (FORC are polarization-field dependences described between saturation field Esat and a variable reversal field Er∈(-Esat, Esat. The FORC diagrams were proposed to describe some characteristics of the switching process in ferroelectrics. The approach is related to the Preisach model which considers the distribution of the elementary switchable units over their coercive and bias fields. The influence of the anisotropic porosity in Pb(Zr,TiO3 bulk ceramics on the FORC distributions demonstrated the existence of a positive/negative bias as a result of the confinement induced by anisotropy. The reducing of grain size in Ba(Zr,TiO3 ceramics causes an increase of the ratio of the reversible/irreversible components of the polarization on the FORC distribution indicating the tendency of system towards the superparaelectric state. The FORC method demonstrates to provide a kind of ‘fingerprinting’ of various types of switching characteristics in ferroic systems.

  5. Contact mechanics of reverse engineered distal humeral hemiarthroplasty implants.

    Science.gov (United States)

    Willing, Ryan; King, Graham J W; Johnson, James A

    2015-11-26

    Erosion of articular cartilage is a concern following distal humeral hemiarthroplasty, because native cartilage surfaces are placed in contact with stiff metallic implant components, which causes decreases in contact area and increases in contact stresses. Recently, reverse engineered implants have been proposed which are intended to promote more natural contact mechanics by reproducing the native bone or cartilage shape. In this study, finite element modeling is used in order to calculate changes in cartilage contact areas and stresses following distal humeral hemiarthroplasty with commercially available and reverse engineered implant designs. At the ulna, decreases in contact area were -34±3% (p=0.002), -27±1% (pengineered and cartilage reverse engineered designs, respectively. Peak contact stresses increased by 461±57% (p=0.008), 387±127% (p=0.229) and 165±16% (p=0.003). At the radius, decreases in contact area were -21±3% (p=0.013), -13±2% (p0.999), 241±32% (p=0.010) and 61±10% (p=0.021). Between the three different implant designs, the cartilage reverse engineered design yielded the largest contact areas and lowest contact stresses, but was still unable to reproduce the contact mechanics of the native joint. These findings align with a growing body of evidence indicating that although reverse engineered hemiarthroplasty implants can provide small improvements in contact mechanics when compared with commercially available designs, further optimization of shape and material properties is required in order reproduce native joint contact mechanics.

  6. Mechanism Study of Reversible Resistivity Change in Oxide Thin Film

    Energy Technology Data Exchange (ETDEWEB)

    Hong, S.; Chang, S. H.; Phatak, C.; Magyari-Kope, Blanka; Nishi, Y; Chattopadhyay, Soma; Kim, Jung Ho

    2015-01-01

    Here we present our findings related to the mechanism of reversible resistivity in Pt/TiO2/Pt cells and in Ta2O5 thin films. Our findings for Pt/TiO2/Pt cells indicate that there exists a photovoltaic-like effect, which modulates the resistance reversibly by a few orders of magnitude, depending on the intensity of impinging x-rays. We found that this effect, combined with the x-ray irradiation induced phase transition confirmed by transmission electron microscopy, triggers a non-volatile reversible resistance change. For Ta2O5 thin films, we found that there are strong correlations among oxygen vacancy number and positions and energy gaps. Ab initio band structure calculations explain the evolution of the electronic excitation spectrum as a function of oxygen vacancy number and positions and importantly provide a predictive description of the oxygen deficient Ta oxide that may improve the desired performance based on atomic level design.

  7. Stochastic effect on thermally magnetization reversal in Pico second ordering process

    Science.gov (United States)

    Sadnawanto, W.; Purnama, Budi

    2014-10-01

    In this study a magnetization reversal dynamics observed in the heat assisted magnetization reversal of CoPtCr perpendicularly magnetized material in the order of a pico second ordering time. Observation of heat assisted magnetization reversal have been using micromagnetic simulation solved by the Landau-Lifshitz-Gilbert equation. The magnetic dot size of the simulation was 50 nm × 50 nm × 20 nm. The perpendicularly anisotropy constant CoPtCr was 2 × 106 erg/cc. Micro-magnetic simulations was carried out systematically by providing pulse-external field with varying pulse duration of 25 ps to 1 ns. The decrease of the minimum field required for reversal observed in this simulation until it reached 90% for 125 ps cooled ordering time. The results also was showed that this sequence simulation running had a zero probability of switching at zero fields. It was indicated that the heat stochastic effect dominated in the mechanism reduced of the field was required for along to the magnetic field direction.

  8. Ordering in mechanical geometry theorem proving

    Institute of Scientific and Technical Information of China (English)

    李洪波¥

    1997-01-01

    Ordering in mechanical geometry theorem proving is studied from geometric viewpoint and some new ideas are proposed. For Thebault’s theorem which is the most difficult theorem that has ever been proved by Wu’ s method, a very simple proof using Wu’s method under a linear order is discovered.

  9. Higher order mechanics on graded bundles

    Science.gov (United States)

    Bruce, Andrew James; Grabowska, Katarzyna; Grabowski, Janusz

    2015-05-01

    In this paper we develop a geometric approach to higher order mechanics on graded bundles in both, the Lagrangian and Hamiltonian formalism, via the recently discovered weighted algebroids. We present the corresponding Tulczyjew triple for this higher order situation and derive in this framework the phase equations from an arbitrary (also singular) Lagrangian or Hamiltonian, as well as the Euler-Lagrange equations. As important examples, we geometrically derive the classical higher order Euler-Lagrange equations and analogous reduced equations for invariant higher order Lagrangians on Lie groupoids.

  10. Remanence Properties and Magnetization Reversal Mechanism of Fe Nanowire Arrays

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-Bo; LIU Qing-Fang; XUE De-Sheng; LI Fa-Shen

    2004-01-01

    @@ Remanence properties and magnetization reversal mechanism of Fe nanowire arrays with diameters 16 nm and130nm are studied. Isothermal remanent magnetization curves show that the contribution of irreversible magnetization decreases when the diameter changes from 16nm to 130nm. The remanence coercivities of these nanowires obtained in dc-demagnetization curve are about 2400 Oe and 800 Oe, respectively. The magnetization reversal mechanism is different in these two samples. For the nanowire array with diameter 16nm, both the nucleation and the pinning have effects on magnetization reversal mechanism, and the pinning field (about 2500Oe) is larger than the nucleation field (about 2200 Oe). However, for the nanowire array with diameter 130nm,the magnetization reversal mechanism is dominated by the pinning effect of domain walls.

  11. Hysteresis in single and polycrystalline iron thin films: Major and minor loops, first order reversal curves, and Preisach modeling

    Science.gov (United States)

    Cao, Yue; Xu, Ke; Jiang, Weilin; Droubay, Timothy; Ramuhalli, Pradeep; Edwards, Danny; Johnson, Bradley R.; McCloy, John

    2015-12-01

    Hysteretic behavior was studied in a series of Fe thin films, grown by molecular beam epitaxy, having different grain sizes and grown on different substrates. Major and minor loops and first order reversal curves (FORCs) were collected to investigate magnetization mechanisms and domain behavior under different magnetic histories. The minor loop coefficient and major loop coercivity increase with decreasing grain size due to higher defect concentration resisting domain wall movement. First order reversal curves allowed estimation of the contribution of irreversible and reversible susceptibilities and switching field distribution. The differences in shape of the major loops and first order reversal curves are described using a classical Preisach model with distributions of hysterons of different switching fields, providing a powerful visualization tool to help understand the magnetization switching behavior of Fe films as manifested in various experimental magnetization measurements.

  12. Order from disorder in closed systems via time reversal violation

    CERN Document Server

    Goldman, T

    2012-01-01

    Definitions of entropy usually assume time-reversal (T) invariance of interactions, yet microscopically T is known to be violated. We present a detailed computational example of (uncharged) particle species separation (Maxwell demon) using an interaction that violates both parity (P) and T so that PT is preserved, consistent with the CPT invariance required in quantum field theory (C is charge conjugation). This illustrates how T-violating forces can produce more organized states from disorganized ones, contrary to expectations based on increase of entropy. We also outline several scenarios in which T-violating forces could lead to an organized state in the early Universe, starting from a still earlier disorganized state.

  13. Increasing cognitive load to facilitate lie detection: the benefit of recalling an event in reverse order.

    Science.gov (United States)

    Vrij, Aldert; Mann, Samantha A; Fisher, Ronald P; Leal, Sharon; Milne, Rebecca; Bull, Ray

    2008-06-01

    In two experiments, we tested the hypotheses that (a) the difference between liars and truth tellers will be greater when interviewees report their stories in reverse order than in chronological order, and (b) instructing interviewees to recall their stories in reverse order will facilitate detecting deception. In Experiment 1, 80 mock suspects told the truth or lied about a staged event and did or did not report their stories in reverse order. The reverse order interviews contained many more cues to deceit than the control interviews. In Experiment 2, 55 police officers watched a selection of the videotaped interviews of Experiment 1 and made veracity judgements. Requesting suspects to convey their stories in reverse order improved police observers' ability to detect deception and did not result in a response bias.

  14. Mechanisms of Cytochrome C Extraction by Reverse Micelles

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The extraction of cytochrome C was carried out by means of phase transfer technique with three different reverse micellar systems, i.e., a CTAB micellar solution in n-butyl alcohol-chloroform(volume ratio 4∶1), an AOT micellar solution in isooctane and a SDSS-D2EHPA micellar solution in isooctane. The extraction mechanisms were studied. The results show that the extraction mechanisms for the same proteins with different types of reverse micellar systems can be distinct. The extraction of cytochrome C with CTAB and SDSS-D2EHPA reverse micellar systems are carried out according to the mechanism of electrostatic interaction. However, in the extraction of cytochrome C with the AOT reverse micellar system, the electrostatic interaction between the protein and the surfactant is not important.

  15. Implementation procedure for the generalized moving Preisach model based on a first order reversal curve diagram

    Institute of Scientific and Technical Information of China (English)

    HAN Yong; ZHU Jie

    2009-01-01

    Ftrst order reversal curves (FORC) of nanoeomposite Nd2Fe14B/Fe3B magnetic materials were measured to attain a FORC diagram, which characterizes reversible magnetization, irreversible magnetization, and magnetic interactions in a hysteresis system. Then, generalized mov-ing Preisach model (GMPM) was implemented based on the FORC diagram. Reversible and irreversible magnetizations shown in FORCs and a FORC diagram were used as an input of GMPM. Coupling interaction between reversible and irreversible magnetizations was added when calculating reversible magnetization. Meanwhile, irreversible magnetic moments' interaction was approximately represented by mean field interaction. The result shows that the simulated main curves mostly coincide with the experimental curves.

  16. Conformal higher-order viscoelastic fluid mechanics

    CERN Document Server

    Fukuma, Masafumi

    2012-01-01

    We present a generally covariant formulation of conformal higher-order viscoelastic fluid mechanics with strain allowed to take arbitrarily large values. We give a general prescription to determine the dynamics of a relativistic viscoelastic fluid in a way consistent with the hypothesis of local thermodynamic equilibrium and the second law of thermodynamics. We then elaborately study the transient time scales at which the strain almost relaxes and becomes proportional to the gradients of velocity. We particularly show that a conformal second-order fluid with all possible parameters in the constitutive equations can be obtained without breaking the hypothesis of local thermodynamic equilibrium, if the conformal fluid is defined as the long time limit of a conformal second-order viscoelastic system. We also discuss how local thermodynamic equilibrium could be understood in the context of the fluid/gravity correspondence.

  17. Conformal higher-order viscoelastic fluid mechanics

    Science.gov (United States)

    Fukuma, Masafumi; Sakatani, Yuho

    2012-06-01

    We present a generally covariant formulation of conformal higher-order viscoelastic fluid mechanics with strain allowed to take arbitrarily large values. We give a general prescription to determine the dynamics of a relativistic viscoelastic fluid in a way consistent with the hypothesis of local thermodynamic equilibrium and the second law of thermodynamics. We then elaborately study the transient time scales at which the strain almost relaxes and becomes proportional to the gradients of velocity. We particularly show that a conformal second-order fluid with all possible parameters in the constitutive equations can be obtained without breaking the hypothesis of local thermodynamic equilibrium, if the conformal fluid is defined as the long time limit of a conformal second-order viscoelastic system. We also discuss how local thermodynamic equilibrium could be understood in the context of the fluid/gravity correspondence.

  18. Discrete Methods Based on First Order Reversal Curves to Identify Preisach Model of Smart Materials

    Institute of Scientific and Technical Information of China (English)

    LI Fan; ZHAO Jian-hui

    2007-01-01

    Preisach model is widely used in modeling of smart materials. Although first order reversal curves (FORCs) have often found applications in the fields of physics and geology, they are able to serve to identify Preisach model. In order to clarify the relationship between the Preisach model and the first order reversal curves, this paper is directed towards: (1) giving the reason a first order reversal curve is introduced; (2) presenting, for identifying Preisach model, two discrete methods, which are analytically based on first order reversal curves. Herein also is indicated the solution's uniqueness of these two identifying methods. At last, the validity of these two methods is verified by simulating a real smart actuator both methods have been applied to.

  19. Hysteresis in single and polycrystalline iron thin films: Major and minor loops, first order reversal curves, and Preisach modeling

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Yue; Xu, Ke [Materials Science and Engineering Program, Washington State University, Pullman, WA 99164 (United States); Jiang, Weilin; Droubay, Timothy; Ramuhalli, Pradeep; Edwards, Danny; Johnson, Bradley R. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); McCloy, John, E-mail: john.mccloy@wsu.edu [Materials Science and Engineering Program, Washington State University, Pullman, WA 99164 (United States); School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States)

    2015-12-01

    Hysteretic behavior was studied in a series of Fe thin films, grown by molecular beam epitaxy, having different grain sizes and grown on different substrates. Major and minor loops and first order reversal curves (FORCs) were collected to investigate magnetization mechanisms and domain behavior under different magnetic histories. The minor loop coefficient and major loop coercivity increase with decreasing grain size due to higher defect concentration resisting domain wall movement. First order reversal curves allowed estimation of the contribution of irreversible and reversible susceptibilities and switching field distribution. The differences in shape of the major loops and first order reversal curves are described using a classical Preisach model with distributions of hysterons of different switching fields, providing a powerful visualization tool to help understand the magnetization switching behavior of Fe films as manifested in various experimental magnetization measurements. - Highlights: • Iron thin films grown by molecular beam epitaxy (MBE) with different substrates and conditions. • Major and minor loops, first order reversal curves (FORCs) measured on same samples. • Parameters from various magnetic measurements compared and correlated. • Hysteresis modeling used to understand different switching field distributions caused by defects.

  20. Reverse mechanical after effect during hydrogenation of zone refined iron

    Energy Technology Data Exchange (ETDEWEB)

    Spivak, L.V.; Skryabina, N.E.; Kurmaeva, L.D.; Smirnov, L.V. (Permskij Gosudarstvennyj Univ. (USSR); AN SSSR, Sverdlovsk. Inst. Fiziki Metallov)

    1984-12-01

    The relationship between the process of hydrogenation and the reverse mechanical after effect (RMA) microplastic deformation in the zone refined iron has been studied. Metallographic investigations and mechanical testing of the samples hydrogenated under torsional strain have been performed. It is shown that in the zone refined iron the formation of voids responsible for irreversible hydrogen embrittlement does not occur, but the hydrogen-initiated RMA strain is conserved, i. e. the RMA effects are independent of the presence of discontinuities.

  1. A study on dynamic heat assisted magnetization reversal mechanisms under insufficient reversal field conditions

    Science.gov (United States)

    Chen, Y. J.; Yang, H. Z.; Leong, S. H.; Wu, B. L.; Asbahi, M.; Yu Ko, Hnin Yu; Yang, J. K. W.; Ng, V.

    2014-10-01

    We report an experimental study on the dynamic thermomagnetic (TM) reversal mechanisms at around Curie temperature (Tc) for isolated 60 nm pitch single-domain [Co/Pd] islands heated by a 1.5 μm spot size laser pulse under an applied magnetic reversal field (Hr). Magnetic force microscopy (MFM) observations with high resolution MFM tips clearly showed randomly trapped non-switched islands within the laser irradiated spot after dynamic TM reversal process with insufficient Hr strength. This observation provides direct experimental evidence by MFM of a large magnetization switching variation due to increased thermal fluctuation/agitation over magnetization energy at the elevated temperature of around Tc. The average percentage of non-switched islands/magnetization was further found to be inversely proportional to the applied reversal field Hr for incomplete magnetization reversal when Hr is less than 13% of the island coercivity (Hc), showing an increased switching field distribution (SFD) at elevated temperature of around Tc (where main contributions to SFD broadening are from Tc distribution and stronger thermal fluctuations). Our experimental study and results provide better understanding and insight on practical heat assisted magnetic recording (HAMR) process and recording performance, including HAMR writing magnetization dynamics induced SFD as well as associated DC saturation noise that limits areal density, as were previously observed and investigated by theoretical simulations.

  2. Left Atrial Reverse Remodeling: Mechanisms, Evaluation, and Clinical Significance.

    Science.gov (United States)

    Thomas, Liza; Abhayaratna, Walter P

    2017-01-01

    The left atrium is considered a biomarker for adverse cardiovascular outcomes, particularly in patients with left ventricular diastolic dysfunction and atrial fibrillation in whom left atrial (LA) enlargement is of prognostic importance. LA enlargement with a consequent decrease in LA function represents maladaptive structural and functional "remodeling" that in turn promotes electrical remodeling and a milieu conducive for incident atrial fibrillation. Medical and nonmedical interventions may arrest this pathophysiologic process to the extent that subsequent reverse remodeling results in a reduction in LA size and improvement in LA function. This review examines cellular and basic mechanisms involved in LA remodeling, evaluates the noninvasive techniques that can assess these changes, and examines potential mechanisms that may initiate reverse remodeling.

  3. Microstructural evolution and magnetization reversal mechanism of CoPt films with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, K K M; Chen, J S; Chow, G M [Department of Materials Science and Engineering, National University of Singapore, Singapore 119260 (Singapore); Hu, J F [Data Storage Institute, Singapore 117608 (Singapore)], E-mail: msecgm@nus.edu.sg

    2009-01-07

    Microstructural evolution and magnetization reversal mechanisms of perpendicular magnetic anisotropic Co{sub 72}Pt{sub 28} films were investigated. Results showed that in the initial stage of film growth, the Co{sub 72}Pt{sub 28} film was continuous and followed a dome-shaped structure with increasing film thickness. When the film thickness further increased above a certain critical value, the film growth acquired an inverted frustum shape structure and increased the intergranular magnetic interaction. The magnetization reversal mechanism showed a strong dependence on microstructures. The magnetization reversal followed the domain wall motion behaviour when the film was continuous and deviated towards the Stoner-Wohlfarth (S-W) model in the dome-shaped regime. A further deviation away from the S-W model was observed, when the film acquired an inverted frustum shape structure in order to minimize the surface energy.

  4. Reversible Guest Exchange Mechanisms in Supramolecular Host-GuestAssemblies

    Energy Technology Data Exchange (ETDEWEB)

    Pluth, Michael D.; Raymond, Kenneth N.

    2006-09-01

    Synthetic chemists have provided a wide array of supramolecular assemblies able to encapsulate guest molecules. The scope of this tutorial review focuses on supramolecular host molecules capable of reversibly encapsulating polyatomic guests. Much work has been done to determine the mechanism of guest encapsulation and guest release. This review covers common methods of monitoring and characterizing guest exchange such as NMR, UV-VIS, mass spectroscopy, electrochemistry, and calorimetry and also presents representative examples of guest exchange mechanisms. The guest exchange mechanisms of hemicarcerands, cucurbiturils, hydrogen-bonded assemblies, and metal-ligand assemblies are discussed. Special attention is given to systems which exhibit constrictive binding, a motif common in supramolecular guest exchange systems.

  5. Large Magnetization and Reversible Magnetocaloric Effect at the Second-Order Magnetic Transition in Heusler Materials.

    Science.gov (United States)

    Singh, Sanjay; Caron, Luana; D'Souza, Sunil Wilfred; Fichtner, Tina; Porcari, Giacomo; Fabbrici, Simone; Shekhar, Chandra; Chadov, Stanislav; Solzi, Massimo; Felser, Claudia

    2016-05-01

    In contrast to rare-earth-based materials, cheaper and more environmentally friendly candidates for cooling applications are found within the family of Ni-Mn Heusler alloys. Initial interest in these materials is focused on the first-order magnetostructural transitions. However, large hysteresis makes a magnetocaloric cycle irreversible. Alternatively, here it is shown how the Heusler family can be used to optimize reversible second-order magnetic phase transitions for magnetocaloric applications.

  6. Investigation of the switching characteristics in ferroelectrics by first-order reversal curve diagrams

    Energy Technology Data Exchange (ETDEWEB)

    Stancu, Alexandru [Solid State and Theoretical Physics Department, Al. I. Cuza University, Blvd. Carol 11, Iasi 700506 (Romania)]. E-mail: alstancu@uaic.ro; Mitoseriu, Liliana [Solid State and Theoretical Physics Department, Al. I. Cuza University, Blvd. Carol 11, Iasi 700506 (Romania); Stoleriu, Laurentiu [Solid State and Theoretical Physics Department, Al. I. Cuza University, Blvd. Carol 11, Iasi 700506 (Romania); Piazza, Daniele [CNR-ISTEC, Via Granarolo 64, I-48018 Faenza (Italy); Galassi, Carmen [CNR-ISTEC, Via Granarolo 64, I-48018 Faenza (Italy); Ricinschi, Dan [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Okuyama, Masanori [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan)

    2006-02-01

    First-order reversal curves (FORC) diagrams are proposed for describing the switching properties in ferroelectric materials. The method is applied for Pb(Zr,Ti)O{sub 3} (PZT) ferroelectric ceramics and films with different P(E) hysteresis and microstructural characteristics. The separation of the reversible and irreversible contributions to the ferroelectric polarization is explained in terms of microstructural characteristics of the investigated samples. The influence of parameters as field frequency, crystallite orientation, ferroelectric fatigue and porosity degree on the FORC diagrams is discussed.

  7. Reversal of elution order for profen acid enantiomers in packed-column SFC on Chiralpak AD.

    Science.gov (United States)

    Gyllenhaal, Olle; Stefansson, Morgan

    2005-05-15

    Enantiomeric separations of four 2-substituted propionic acid drugs have been studied using packed-column supercritical fluid chromatography (SFC) with amylose tris(3,5-dimethylphenylcarbamate) coated on silica as support (Chiralpak AD). Under standard conditions (i.e., flow rate, 1.5 ml/min; column temperature, 30 degrees C; back-pressure, 150 bar), the order of elution could be reversed when the polar alcohol modifier methanol in carbon dioxide was replaced by 2-propanol for ibuprofen, ketoprofen, and naproxen. For flurbiprofen, with the highest selectivity factor, no reversal was observed, although selectivity was reduced significantly with higher alcohols. Naproxen and flurbiprofen were also investigated with 2-butanol and 2-pentanol. The former showed reversal of elution order but not the latter. For higher alcohol modifiers, including 2-propanol, the peak symmetry was poor but could be improved by addition of citric acid in the alcohol modifier. These results stress the importance to investigate enantiomer elution order during the development of enantioselective methods and when chromatographic conditions are optimized. Preliminary experiments with column temperatures over the range of -15 to 45 degrees C revealed that, in a few cases, reversal took place with a change in temperature only.

  8. Investigation of Third Order Optical Nonlinearity and Reverse Saturable Absorption of Octa-alkoxy Metallophthalocyanines

    Science.gov (United States)

    Sanghadasa, Mohan; Shin, In-Seek; Barr, Thomas A.; Clark, Ronald D.; Guo, Huai-Song; Martinez, Angela; Penn, Benjamin G.

    1998-01-01

    In recent years, there has been a growing interest in the development of passive optical power limiters for the protection of the human eye and solid-state sensors from damage caused by energetic light pulses and also for other switching applications. One of the key issues involved is the search for appropriate materials that show effective reverse saturable absorption. Phthalocyanines seem to be good candidates for such applications because of their higher third order nonlinearity and the unique electronic absorption characteristics. A series of 1,4,8,11,15, 18,22,25-octa-alkoxy metallophthalocyanines containing various central metal atoms such as zinc, copper, palladium, cobalt and nickel were characterized for their third order nonlinearity and for their nonlinear absorptive properties to evaluate their suitability to function as reverse saturable absorbers.

  9. Time-reversal symmetry breaking hidden order in Sr2(Ir,Rh)O4

    Science.gov (United States)

    Jeong, Jaehong; Sidis, Yvan; Louat, Alex; Brouet, Véronique; Bourges, Philippe

    2017-04-01

    Layered 5d transition iridium oxides, Sr2(Ir,Rh)O4, are described as unconventional Mott insulators with strong spin-orbit coupling. The undoped compound, Sr2IrO4, is a nearly ideal two-dimensional pseudospin-1/2 Heisenberg antiferromagnet, similarly to the insulating parent compound of high-temperature superconducting copper oxides. Using polarized neutron diffraction, we here report a hidden magnetic order in pure and doped Sr2(Ir,Rh)O4, distinct from the usual antiferromagnetic pseudospin ordering. We find that time-reversal symmetry is broken while the lattice translation invariance is preserved in the hidden order phase. The onset temperature matches that of the odd-parity hidden order recently highlighted using optical second-harmonic generation experiments. The novel magnetic order and broken symmetries can be explained by the loop-current model, previously predicted for the copper oxide superconductors.

  10. Octocoral mitochondrial genomes provide insights into the phylogenetic history of gene order rearrangements, order reversals, and cnidarian phylogenetics.

    Science.gov (United States)

    Figueroa, Diego F; Baco, Amy R

    2014-12-24

    We use full mitochondrial genomes to test the robustness of the phylogeny of the Octocorallia, to determine the evolutionary pathway for the five known mitochondrial gene rearrangements in octocorals, and to test the suitability of using mitochondrial genomes for higher taxonomic-level phylogenetic reconstructions. Our phylogeny supports three major divisions within the Octocorallia and show that Paragorgiidae is paraphyletic, with Sibogagorgia forming a sister branch to the Coralliidae. Furthermore, Sibogagorgia cauliflora has what is presumed to be the ancestral gene order in octocorals, but the presence of a pair of inverted repeat sequences suggest that this gene order was not conserved but rather evolved back to this apparent ancestral state. Based on this we recommend the resurrection of the family Sibogagorgiidae to fix the paraphyly of the Paragorgiidae. This is the first study to show that in the Octocorallia, mitochondrial gene orders have evolved back to an ancestral state after going through a gene rearrangement, with at least one of the gene orders evolving independently in different lineages. A number of studies have used gene boundaries to determine the type of mitochondrial gene arrangement present. However, our findings suggest that this method known as gene junction screening may miss evolutionary reversals. Additionally, substitution saturation analysis demonstrates that while whole mitochondrial genomes can be used effectively for phylogenetic analyses within Octocorallia, their utility at higher taxonomic levels within Cnidaria is inadequate. Therefore for phylogenetic reconstruction at taxonomic levels higher than subclass within the Cnidaria, nuclear genes will be required, even when whole mitochondrial genomes are available.

  11. Order in de Broglie - Bohm quantum mechanics

    CERN Document Server

    Contopoulos, G; Efthymiopoulos, C

    2012-01-01

    A usual assumption in the so-called {\\it de Broglie - Bohm} approach to quantum dynamics is that the quantum trajectories subject to typical `guiding' wavefunctions turn to be quite irregular, i.e. {\\it chaotic} (in the dynamical systems' sense). In the present paper, we consider mainly cases in which the quantum trajectories are {\\it ordered}, i.e. they have zero Lyapunov characteristic numbers. We use perturbative methods to establish the existence of such trajectories from a theoretical point of view, while we analyze their properties via numerical experiments. Using a 2D harmonic oscillator system, we first establish conditions under which a trajectory can be shown to avoid close encounters with a moving nodal point, thus avoiding the source of chaos in this system. We then consider series expansions for trajectories both in the interior and the exterior of the domain covered by nodal lines, probing the domain of convergence as well as how successful the series are in comparison with numerical computation...

  12. Imaging of first-order surface-related multiples by reverse-time migration

    Science.gov (United States)

    Liu, Xuejian; Liu, Yike; Hu, Hao; Li, Peng; Khan, Majid

    2017-02-01

    Surface-related multiples have been utilized in the reverse-time migration (RTM) procedures, and additional illumination for subsurface can be provided. Meanwhile, many cross-talks are generated from undesired interactions between forward- and backward-propagated seismic waves. In this paper, subsequent to analysing and categorizing these cross-talks, we propose RTM of first-order multiples to avoid most undesired interactions in RTM of all-order multiples, where only primaries are forward-propagated and crosscorrelated with the backward-propagated first-order multiples. With primaries and multiples separated during regular seismic data processing as the input data, first-order multiples can be obtained by a two-step scheme: (1) the dual-prediction of higher-order multiples; and (2) the adaptive subtraction of predicted higher-order multiples from all-order multiples within local offset-time windows. In numerical experiments, two synthetic and a marine field data sets are used, where different cross-talks generated by RTM of all-order multiples can be identified and the proposed RTM of first-order multiples can provide a very interpretable image with a few cross-talks.

  13. Linear response, multi-order grating interferometry using a reversal shearing imaging system.

    Science.gov (United States)

    Tao, Zhang; Tan, Jiubin; Cui, Jiwen

    2015-10-01

    Linear response, multi-order grating interferometry is proposed to measure grating displacement. The system, a combination of a reversal shearing interferometer and an imaging system, enables calculating multi-order, integrated intensity signals with a linear waveform response. A theoretical multi-order model for the linear response signal analysis is presented with a Fourier series expansion. The results of the experiment, which prove the validity of the theoretical model, indicate a linear response to displacement with a linearity of 98.7% and a resolution of 10 nm. We conclude that the proposed method enables the development of a new class of potent linear response grating interferometry for displacement metrology.

  14. First-order reversal curves acquired by a high precision ac induction magnetometer.

    Science.gov (United States)

    Béron, F; Soares, G; Pirota, K R

    2011-06-01

    We present a setup allowing to characterize the local irreversible behavior of soft magnetic samples. It is achieved by modifying a conventional ac induction magnetometer in order to measure first-order reversal curves (FORCs), a magnetostatic characterization technique. The required modifications were performed on a home-made setup allowing high precision measurement, with sensibility less than 0.005 Oe for the applied field and 10(-6) emu for the magnetization. The main crucial point for the FORCs accuracy is the constancy of the applied field sweep rate, because of the magnetic viscosity. Therefore, instead of the common way to work at constant frequency, each FORC is acquired at a slightly different frequency, in order to keep the field variation constant in time. The obtained results exhibit the consequences of magnetic viscosity, thus opening up the path of studying this phenomenon for soft magnetic materials.

  15. Rejection mechanisms for contaminants in polymeric reverse osmosis membranes

    CERN Document Server

    Shen, Meng; Lueptow, Richard M

    2016-01-01

    Despite the success of reverse osmosis (RO) for water purification, the molecular-level physico-chemical processes of contaminant rejection are not well understood. Here we carry out NEMD simulations on a model polyamide RO membrane to understand the mechanisms of transport and rejection of both ionic and neutral contaminants in water. We observe that the rejection changes non-monotonously with ion sizes. In particular, the rejection of urea, 2.4 A radius, is higher than ethanol, 2.6 A radius, and the rejections for organic solutes, 2.2-2.8 A radius, are lower than Na+, 1.4 A radius, or Cl-, 2.3 A radius. We show that this can be explained in terms of the solute accessible intermolecular volume in the membrane and the solute-water pair interaction energy. If the smallest open spaces in the membrane's molecular structure are all larger than the hydrated solute, then the solute-water pair interaction energy does not matter. However, when the open spaces in the polymeric structure are such that solutes have to s...

  16. First-order reversal curve probing of spatially resolved polarization switching dynamics in ferroelectric nanocapacitors.

    Science.gov (United States)

    Kim, Yunseok; Kumar, Amit; Ovchinnikov, Oleg; Jesse, Stephen; Han, Hee; Pantel, Daniel; Vrejoiu, Ionela; Lee, Woo; Hesse, Dietrich; Alexe, Marin; Kalinin, Sergei V

    2012-01-24

    Spatially resolved polarization switching in ferroelectric nanocapacitors was studied on the sub-25 nm scale using the first-order reversal curve (FORC) method. The chosen capacitor geometry allows both high-veracity observation of the domain structure and mapping of polarization switching in a uniform field, synergistically combining microstructural observations and probing of uniform-field polarization responses as relevant to device operation. A classical Kolmogorov-Avrami-Ishibashi model has been adapted to the voltage domain, and the individual switching dynamics of the FORC response curves are well approximated by the adapted model. The comparison with microstructures suggests a strong spatial variability of the switching dynamics inside the nanocapacitors.

  17. An efficient higher-order PML in WLP-FDTD method for time reversed wave simulation

    Science.gov (United States)

    Wei, Xiao-Kun; Shao, Wei; Ou, Haiyan; Wang, Bing-Zhong

    2016-09-01

    Derived from a stretched coordinate formulation, a higher-order complex frequency shifted (CFS) perfectly matched layer (PML) is proposed for the unconditionally stable finite-difference time-domain (FDTD) method based on weighted Laguerre polynomials (WLPs). The higher-order PML is implemented with an auxiliary differential equation (ADE) approach. In order to further improve absorbing performance, the parameter values of stretching functions in the higher-order PML are optimized by the multi-objective genetic algorithm (MOGA). The optimal solutions can be chosen from the Pareto front for trading-off between two independent objectives. It is shown in a numerical test that the higher-order PML is efficient in terms of attenuating propagating waves and reducing late time reflections. Moreover, the higher-order PML can be placed very close to the wall when analyzing the channel characteristics of time reversal (TR) waves in a multipath indoor environment. Numerical examples of TR wave propagation demonstrate the availability of the proposed method.

  18. The reversibility and first-order nature of liquid-liquid transition in a molecular liquid

    Science.gov (United States)

    Kobayashi, Mika; Tanaka, Hajime

    2016-11-01

    Liquid-liquid transition is an intriguing phenomenon in which a liquid transforms into another liquid via the first-order transition. For molecular liquids, however, it always takes place in a supercooled liquid state metastable against crystallization, which has led to a number of serious debates concerning its origin: liquid-liquid transition versus unusual nano-crystal formation. Thus, there have so far been no single example free from such debates, to the best of our knowledge. Here we show experimental evidence that the transition is truly liquid-liquid transition and not nano-crystallization for a molecular liquid, triphenyl phosphite. We kinetically isolate the reverse liquid-liquid transition from glass transition and crystallization with a high heating rate of flash differential scanning calorimetry, and prove the reversibility and first-order nature of liquid-liquid transition. Our finding not only deepens our physical understanding of liquid-liquid transition but may also initiate a phase of its research from both fundamental and applications viewpoints.

  19. Time reversibility and nonequilibrium thermodynamics of second-order stochastic processes.

    Science.gov (United States)

    Ge, Hao

    2014-02-01

    Nonequilibrium thermodynamics of a general second-order stochastic system is investigated. We prove that at steady state, under inversion of velocities, the condition of time reversibility over the phase space is equivalent to the antisymmetry of spatial flux and the symmetry of velocity flux. Then we show that the condition of time reversibility alone cannot always guarantee the Maxwell-Boltzmann distribution. Comparing the two conditions together, we find that the frictional force naturally emerges as the unique odd term of the total force at thermodynamic equilibrium, and is followed by the Einstein relation. The two conditions respectively correspond to two previously reported different entropy production rates. In the case where the external force is only position dependent, the two entropy production rates become one. We prove that such an entropy production rate can be decomposed into two non-negative terms, expressed respectively by the conditional mean and variance of the thermodynamic force associated with the irreversible velocity flux at any given spatial coordinate. In the small inertia limit, the former term becomes the entropy production rate of the corresponding overdamped dynamics, while the anomalous entropy production rate originates from the latter term. Furthermore, regarding the connection between the first law and second law, we find that in the steady state of such a limit, the anomalous entropy production rate is also the leading order of the Boltzmann-factor weighted difference between the spatial heat dissipation densities of the underdamped and overdamped dynamics, while their unweighted difference always tends to vanish.

  20. Parity- and Time Reversal-Violating Pion Nucleon Couplings: Higher Order Chiral Matching Relations

    CERN Document Server

    Seng, Chien-Yeah

    2016-01-01

    Parity- and time reversal-violating (PVTV) pion-nucleon couplings govern the magnitude of long-range contributions to nucleon and atomic electric dipole moments. When these couplings arise from chiral symmetry-breaking CP-violating operators, such as the QCD $\\theta$-term or quark chromoelectric dipole moments, one may relate hadronic matrix elements entering the PVTV couplings to nucleon and pion mass shifts by exploiting the corresponding chiral transformation properties at leading order (LO) in the chiral expansion. We compute the higher-order contributions to the lowest order relations arising from chiral loops and next-to-next-to leading order (NNLO) operators. We find that for the QCD $\\theta$-term the higher order contributions are analytic in the quark masses, while for the quark chromoelectric dipole moments and chiral symmetry-breaking four-quark operators, the matching relations also receive non-analytic corrections. Numerical estimates suggest that for the isoscalar PVTV pion-nucleon coupling, the...

  1. Mass transfer mechanism in chiral reversed phase liquid chromatography.

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2014-03-01

    The mechanism of mass transfer in chiral chromatography was investigated using an experimental protocol already applied in RPLC and HILIC chromatography. The different contributions to the reduced height equivalent to a theoretical plate (HETP) include the longitudinal diffusion HETP term, the solid-liquid mass transfer resistance HETP term, the short-range eddy dispersion HETP term, and the long-range eddy dispersion HETP term. Their accurate measurement permits the determination of the adsorption rate constant kads of trans-stilbene enantiomers on a column packed with Lux 5 μm Cellulose-1 particles. The experimental results demonstrate that the number of adsorption-desorption steps per unit time of chiral compounds on polysaccharide-based chiral stationary phases is four orders of magnitude smaller than that of achiral compounds.

  2. Affinity-mediated sorting order reversal of single-walled carbon nanotubes in density gradient ultracentrifugation

    Science.gov (United States)

    Jang, Myungsu; Kim, Somin; Jeong, Haneul; Ju, Sang-Yong

    2016-10-01

    Sorted single-walled carbon nanotubes (SWNTs) are of paramount importance for their utilization in high-end optoelectronic applications. Sodium cholate (SC)-based density gradient ultracentrifugation (DGU) has been instrumental in isolating small diameter (d t) SWNTs. Here, we show that SWNTs wrapped by flavin mononucleotide (FMN) as a dispersing agent are sorted in DGU, and show sorting order reversal behavior, departing from prototypical SC-SWNT trends. Larger d t SWNTs are sorted in lower density (ρ), and buoyant ρ distribution of FMN-SWNT ranges from 1.15-1.25 g cm-3. Such a nanotube layering pattern originates from both the binding affinity between FMN and SWNT and the less-susceptible hydrated volume of remote phosphate sidechains of FMN according to nanotube d t change.

  3. Reversal effect and mechanism of Ginkgo biloba exocarp extracts in multidrug resistance of mice S180 tumor cells

    OpenAIRE

    Hu, Bi-Yuan; Gu, Yun-Hao; Cao, Chen-Jie; Wang, Jun; Han, Dong-Dong; Tang, Ying-Chao; Chen, Hua-Sheng; Xu, Aihua

    2016-01-01

    The aim of the present study was to investigate the reversal effect and its related mechanism of Ginkgo biloba exocarp extracts (GBEEs) in obtained multidrug resistance (MDR) of mice S180 tumor cells in vitro and in vivo. In order to simulate the clinical PFC [cis-dichlorodiamineplatinum, cisplatin (DDP) + fluorouracil (FU), FU+cyclophosphamide and cyclophosphamide] scheme, a gradually increasing dose was administered in a phased induction in order to induce S180 cells in vivo and to make the...

  4. Reversal mechanism in perpendicular media with columnar structure

    NARCIS (Netherlands)

    Wielinga, T.; Lodder, J.C.

    1986-01-01

    A contribution is given to the discussion concerning the nature of the magnetization reversal process in sputtered CoCr recording media with columnar morphology. The paper is restricted to the additional effects on the total perpendicular anisotropy by studying the columnar shape anisotropy and the

  5. Finite dimensional thermo-mechanical systems and second order constraints

    CERN Document Server

    Cendra, Hernán; Amaya, Maximiliano Palacios

    2016-01-01

    In this paper we study a class of physical systems that combine a finite number of mechanical and thermodynamic observables. We call them finite dimensional thermo-mechanical systems. We introduce these systems by means of simple examples. The evolution equations of the involved observables are obtained in each example by using, essentially, the Newton's law and the First Law of Thermodynamics only. We show that such equations are similar to those defining certain mechanical systems with higher order constraints. Moreover, we show that all of the given examples can be described in a variational formalism in terms of second order constrained systems.

  6. First order reversal curves (FORC) analysis of individual magnetic nanostructures using micro-Hall magnetometry

    Science.gov (United States)

    Pohlit, Merlin; Eibisch, Paul; Akbari, Maryam; Porrati, Fabrizio; Huth, Michael; Müller, Jens

    2016-11-01

    Alongside the development of artificially created magnetic nanostructures, micro-Hall magnetometry has proven to be a versatile tool to obtain high-resolution hysteresis loop data and access dynamical properties. Here we explore the application of First Order Reversal Curves (FORC)—a technique well-established in the field of paleomagnetism for studying grain-size and interaction effects in magnetic rocks—to individual and dipolar-coupled arrays of magnetic nanostructures using micro-Hall sensors. A proof-of-principle experiment performed on a macroscopic piece of a floppy disk as a reference sample well known in the literature demonstrates that the FORC diagrams obtained by magnetic stray field measurements using home-built magnetometers are in good agreement with magnetization data obtained by a commercial vibrating sample magnetometer. We discuss in detail the FORC diagrams and their interpretation of three different representative magnetic systems, prepared by the direct-write Focused Electron Beam Induced Deposition (FEBID) technique: (1) an isolated Co-nanoisland showing a simple square-shaped hysteresis loop, (2) a more complex CoFe-alloy nanoisland exhibiting a wasp-waist-type hysteresis, and (3) a cluster of interacting Co-nanoislands. Our findings reveal that the combination of FORC and micro-Hall magnetometry is a promising tool to investigate complex magnetization reversal processes within individual or small ensembles of nanomagnets grown by FEBID or other fabrication methods. The method provides sub-μm spatial resolution and bridges the gap of FORC analysis, commonly used for studying macroscopic samples and rather large arrays, to studies of small ensembles of interacting nanoparticles with the high moment sensitivity inherent to micro-Hall magnetometry.

  7. Effect and mechanism of siderite on reverse flotation of hematite

    Institute of Scientific and Technical Information of China (English)

    Wan-zhong Yin; Dong Li; Xi-mei Luo; Jin Yao; Qian-yu Sun

    2016-01-01

    The effects of siderite on reverse flotation of hematite were investigated using micro flotation, adsorption tests, and Fourier trans-form infrared spectroscopy. The flotation results show that interactions between siderite and quartz are the main reasons that siderite signifi-cantly influences the floatability. The interactions are attributed to dissolved siderite species and fine siderite particles. The interaction due to the dissolved species is, however, dominant. Derjaguin-Landau-Verwey-Overbeek (DLVO) theoretical calculations reveal that adhesion on quartz increases when the siderite particle size decreases and that fine particles partly influence quartz floatability. Chemical solution calcula-tions indicate that the dissolved species of siderite might convert the surface of active quartz to CaCO3 precipitates that can be depressed by starch. The theoretical calculations are in good agreement with the results of adsorption tests and FTIR spectroscopy and explain the reasons why siderite significantly influences reverse flotation of hematite.

  8. hARACNe: improving the accuracy of regulatory model reverse engineering via higher-order data processing inequality tests.

    Science.gov (United States)

    Jang, In Sock; Margolin, Adam; Califano, Andrea

    2013-08-01

    A key goal of systems biology is to elucidate molecular mechanisms associated with physiologic and pathologic phenotypes based on the systematic and genome-wide understanding of cell context-specific molecular interaction models. To this end, reverse engineering approaches have been used to systematically dissect regulatory interactions in a specific tissue, based on the availability of large molecular profile datasets, thus improving our mechanistic understanding of complex diseases, such as cancer. In this paper, we introduce high-order Algorithm for the Reconstruction of Accurate Cellular Network (hARACNe), an extension of the ARACNe algorithm for the dissection of transcriptional regulatory networks. ARACNe uses the data processing inequality (DPI), from information theory, to detect and prune indirect interactions that are unlikely to be mediated by an actual physical interaction. Whereas ARACNe considers only first-order indirect interactions, i.e. those mediated by only one extra regulator, hARACNe considers a generalized form of indirect interactions via two, three or more other regulators. We show that use of higher-order DPI resulted in significantly improved performance, based on transcription factor (TF)-specific ChIP-chip data, as well as on gene expression profile following RNAi-mediated TF silencing.

  9. Neural mechanisms of order information processing in working memory

    Directory of Open Access Journals (Sweden)

    Barbara Dolenc

    2013-11-01

    Full Text Available The ability to encode and maintain the exact order of short sequences of stimuli or events is often crucial to our ability for effective high-order planning. However, it is not yet clear which neural mechanisms underpin this process. Several studies suggest that in comparison with item recognition temporal order coding activates prefrontal and parietal brain regions. Results of various studies tend to favour the hypothesis that the order of the stimuli is represented and encoded on several stages, from primacy and recency estimates to the exact position of the item in a sequence. Different brain regions play a different role in this process. Dorsolateral prefrontal cortex has a more general role in attention, while the premotor cortex is more involved in the process of information grouping. Parietal lobe and hippocampus also play a significant role in order processing as they enable the representation of distance. Moreover, order maintenance is associated with the existence of neural oscillators that operate at different frequencies. Electrophysiological studies revealed that theta and alpha oscillations play an important role in the maintenance of temporal order information. Those EEG oscillations are differentially associated with processes that support the maintenance of order information and item recognition. Various studies suggest a link between prefrontal areas and memory for temporal order, implying that EEG neural oscillations in the prefrontal cortex may play a role in the maintenance of information on temporal order.

  10. REVERSE DESIGN APPROACH FOR MECHANISM TRAJECTORY BASED ON CODE-CHAINS MATCHING

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shuyou; YI Guodong; XU Xiaofeng

    2007-01-01

    Aiming at the problem of reverse-design of mechanism, a method based on the matching of trajectory code-chains is presented. The motion trajectory of mechanism is described with code-chain,which is normalized to simplify the operation of geometric transformation. The geometric transformation formulas of scale, mirror and rotation for trajectory code-chain are defined, and the reverse design for mechanism trajectory is realized through the analysis and solution of similarity matching between the desired trajectory and the predefined trajectory. The algorithm program and prototype system of reverse design for mechanism trajectory are developed. Application samples show that the method can break the restriction of trajectory patterns in matching, meet the demand of partial matching, and overcome the influence of geometric transformation of trajectory on the reverse design for mechanism.

  11. First-order reversal curve (FORC) diagrams of natural and cultured biogenic magnetic particles

    Science.gov (United States)

    Chen, Amy P.; Egli, Ramon; Moskowitz, Bruce M.

    2007-08-01

    First-order reversal curve (FORC) diagrams are rapidly becoming a standard tool for characterizing magnetic particles because they simultaneously incorporate information regarding magnetostatic interaction and domain states. The simplest interpretation of FORC diagrams of single-domain (SD) particles is based on the Neel interpretation of Preisach theory, which predicts that the FORC function is the product of a coercivity and an interaction field distribution. Although the underlying assumptions of this interpretation are not correct, a strictly quantitative model of weakly interacting SD grains proves that the distributions of coercivities and interaction fields can be retrieved from a FORC diagram. To test this model, we present the possibility of a quantitative interpretation of FORC diagrams, and we present measurements of samples containing magnetosomes from cultures of magnetotactic bacteria and from a lake sediment. Two samples are investigated under the electron microscope to characterize the geometrical arrangement of the particles. We find that the clustering of otherwise similar particles has a strong influence on FORC diagrams. We also obtained a crude estimate of packing densities form the FORC diagrams, which were consistent with transmission electron microscopy observations and measurements of the anhysteretic remanent magnetization.

  12. Reversal in time order of interactive events: Collision of inclined rods

    CERN Document Server

    Iyer, Chandru

    2008-01-01

    In the rod and hole paradox as described by Rindler (1961 Am. J. Phys. 29 365-6), a rigid rod moves at high speed over a table towards a hole of the same size. Observations from the inertial frames of the rod and slot are widely different. Rindler explains these differences by the concept of differing perceptions in rigidity. Gron and Johannesen (1993 Eur. J. Phys. 14 97-100) confirmed this aspect by computer simulation where the shapes of the rods are different as observed from the co-moving frames of the rod and slot. Lintel and Gruber (2005 Eur. J. Phys. 26 19-23) presented an approach based on retardation due to speed of stress propagation. In this paper we consider the situation when two parallel rods collide while approaching each other along a line at an inclination with their axis. The collisions of the top and bottom ends are reversed in time order as observed from the two co-moving frames. This result is explained by the concept of extended present derived from the principle of relativity of simulta...

  13. First-order-reversal-curve analysis of Pr-Fe-B-based nanocomposites

    Science.gov (United States)

    Cornejo, D. R.; Peixoto, T. R. F.; Reboh, S.; Fichtner, P. F. P.; de Franco, V. C.; Villas-Boas, V.; Missell, F. P.

    2010-04-01

    Ribbons of nominal composition (Pr9.5Fe84.5B6)0.96Cr0.01(TiC)0.03 were produced by arc-melting and melt-spinning the alloys on a Cu wheel. X-ray diffraction reveals two main phases, one based upon α-Fe and the other upon Pr2Fe14B. The ribbons show exchange spring behavior with Hc=12.5 kOe and (BH)max=13.6 MGOe when these two phases are well coupled. Transmission electron microscopy revealed that the coupled behavior is observed when the microstructure consists predominantly of α-Fe grains (diameter ˜100 nm.) surrounded by hard material containing Pr2Fe14B. A first-order-reversal-curve (FORC) analysis was performed for both a well-coupled sample and a partially-coupled sample. The FORC diagrams show two strong peaks for both the partially-coupled sample and for the well-coupled material. In both cases, the localization of the FORC probability suggests demagnetizing interactions between particles. Switching field distributions were calculated and are consistent with the sample microstructure.

  14. Ruling Out Multi-Order Interference in Quantum Mechanics

    CERN Document Server

    Sinha, Urbasi; Jennewein, Thomas; Laflamme, Raymond; Weihs, Gregor

    2010-01-01

    Quantum mechanics and gravitation are two pillars of modern physics. Despite their success in describing the physical world around us, they seem to be incompatible theories. There are suggestions that one of these theories must be generalized to achieve unification. For example, Born's rule, one of the axioms of quantum mechanics could be violated. Born's rule predicts that quantum interference, as shown by a double slit diffraction experiment, occurs from pairs of paths. A generalized version of quantum mechanics might allow multi-path, i.e. higher order interferences thus leading to a deviation from the theory. We performed a three slit experiment with photons and bounded the magnitude of three path interference to less than 10-2 of the expected two-path interference, thus ruling out third and higher order interference and providing a bound on the accuracy of Born's rule. Our experiment is consistent with the postulate both in semi-classical and quantum regimes.

  15. Ruling out multi-order interference in quantum mechanics.

    Science.gov (United States)

    Sinha, Urbasi; Couteau, Christophe; Jennewein, Thomas; Laflamme, Raymond; Weihs, Gregor

    2010-07-23

    Quantum mechanics and gravitation are two pillars of modern physics. Despite their success in describing the physical world around us, they seem to be incompatible theories. There are suggestions that one of these theories must be generalized to achieve unification. For example, Born's rule--one of the axioms of quantum mechanics--could be violated. Born's rule predicts that quantum interference, as shown by a double-slit diffraction experiment, occurs from pairs of paths. A generalized version of quantum mechanics might allow multipath (i.e., higher-order) interference, thus leading to a deviation from the theory. We performed a three-slit experiment with photons and bounded the magnitude of three-path interference to less than 10(-2) of the expected two-path interference, thus ruling out third- and higher-order interference and providing a bound on the accuracy of Born's rule. Our experiment is consistent with the postulate both in semiclassical and quantum regimes.

  16. Electromagnetic retarded interaction and symmetry violation of time reversal in high order stimulated radiation and absorption processes of light

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It has been proved that when the retarded effect (or multiple moment effect) of radiation fields is taken into account,the high order stimulated radiation and stimulated absorption probabilities of light are not the same so that time reversal symmetry would be violated,though the Hamiltonian of electromagnetic interaction is still unchanged under time reversal. The reason to cause time reversal symmetry violation is that certain filial or partial transition processes of bound atoms are forbidden or cannot be achieved due to the law of energy conservation and the special states of atoms themselves. These restrictions would cause the symmetry violation of time reversal of other filial or partial transition processes which can be actualized really. The symmetry violation is also relative to the asymmetry of initial states of bound atoms before and after time reversal. For the electromagnetic interaction between non-bound atoms and radiation field,there is no such kind of symmetry violation of time reversal. In this way,the current formula on the parameters of stimulated radiation and absorption of light with time reversal sym-metry should be revised. A more reliable foundation can be established for the theories of laser and nonlinear optics in which non-equilibrium processes are in-volved.

  17. Electromagnetic retarded interaction and symmetry violation of time reversal in high order stimulated radiation and absorption processes of light

    Institute of Scientific and Technical Information of China (English)

    MEI XiaoChun

    2008-01-01

    It has been proved that when the retarded effect (or multiple moment effect) of radiation fields is taken into account, the high order stimulated radiation and stimulated absorption probabilities of light are not the same so that time reversal symmetry would be violated, though the Hamiltonian of electromagnetic interaction is still unchanged under time reversal.The reason to cause time reversal symmetry violation is that certain filial or partial transition processes of bound atoms are forbidden or cannot be achieved due to the law of energy conservation and the special states of atoms themselves.These restrictions would cause the symmetry violation of time reversal of other filial or partial transition processes which can be actualized really.The symmetry violation is also relative to the asymmetry of initial states of bound atoms before and after time reversal.For the electromagnetic interaction between non-bound atoms and radiation field, there is no such kind of symmetry violation of time reversal.In this way, the current formula on the parameters of stimulated radiation and absorption of light with time reversal sym-metry should be revised.A more reliable foundation can be established for the theories of laser and nonlinear optics in which non-equilibrium processes are in-volved.

  18. Magnetic unmixing of first-order reversal curve diagrams using principal component analysis

    Science.gov (United States)

    Lascu, Ioan; Harrison, Richard J.; Li, Yuting; Muraszko, Joy R.; Channell, James E. T.; Piotrowski, Alexander M.; Hodell, David A.

    2015-09-01

    We describe a quantitative magnetic unmixing method based on principal component analysis (PCA) of first-order reversal curve (FORC) diagrams. For PCA, we resample FORC distributions on grids that capture diagnostic signatures of single-domain (SD), pseudosingle-domain (PSD), and multidomain (MD) magnetite, as well as of minerals such as hematite. Individual FORC diagrams are recast as linear combinations of end-member (EM) FORC diagrams, located at user-defined positions in PCA space. The EM selection is guided by constraints derived from physical modeling and imposed by data scatter. We investigate temporal variations of two EMs in bulk North Atlantic sediment cores collected from the Rockall Trough and the Iberian Continental Margin. Sediments from each site contain a mixture of magnetosomes and granulometrically distinct detrital magnetite. We also quantify the spatial variation of three EM components (a coarse silt-sized MD component, a fine silt-sized PSD component, and a mixed clay-sized component containing both SD magnetite and hematite) in surficial sediments along the flow path of the North Atlantic Deep Water (NADW). These samples were separated into granulometric fractions, which helped constrain EM definition. PCA-based unmixing reveals systematic variations in EM relative abundance as a function of distance along NADW flow. Finally, we apply PCA to the combined data set of Rockall Trough and NADW sediments, which can be recast as a four-EM mixture, providing enhanced discrimination between components. Our method forms the foundation of a general solution to the problem of unmixing multicomponent magnetic mixtures, a fundamental task of rock magnetic studies.

  19. Molecular simulation of the reversible mechanical unfolding of proteins.

    Science.gov (United States)

    Rathore, Nitin; Yan, Qiliang; de Pablo, Juan J

    2004-03-22

    In this work we have combined a Wang-Landau sampling scheme [F. Wang and D. Landau, Phys. Rev. Lett. 86, 2050 (2001)] with an expanded ensemble formalism to yield a simple and powerful method for computing potentials of mean force. The new method is implemented to investigate the mechanical deformation of proteins. Comparisons are made with analytical results for simple model systems such as harmonic springs and Rouse chains. The method is then illustrated on a model 15-residue alanine molecule in an implicit solvent. Results for mechanical unfolding of this oligopeptide are compared to those of steered molecular dynamics calculations.

  20. Mechanism of Electro-Coagulation with Al/Fe Periodically Reversing Treating Berberine Pharmaceutical Wastewater

    Science.gov (United States)

    Sun, Zhaonan; Liu, Zheng; Hu, Xiaomin

    2017-05-01

    The method of treating pharmaceutical wastewater by electro-coagulation with Al/Fe periodically reversing (ECPR) was proposed based on traditional electrochemical method. The principle of ECPR was generalized. Mechanism of ECPR to treat berberine pharmaceutical wastewater was investigated. Treatability and mechanism studies were conducted under laboratory conditions. For berberine wastewater (800 mg/L), decolourization efficiency and COD removal efficiency were highest to 98% and 95% respectively when voltage was 8V, reaction time was 60 min, alternating period was 10 S electrolyte concentration was 0.015 mol/L, stirring speed was 750 rpm, pH value was 3-10 and distance between two plates was 0.6 cm. For removal berberine, flocculation, floatation and oxidation provided 73%, 8% and 18% removal efficiency, which can be inferred by analysing UV-visible absorption spectrum, acidification experiment, EDTA shielding experiment, structure-activity relationship, oxidation and floatation. Meanwhile decolourization and COD removal conformed to apparent pseudo-first order and zero-order kinetics for 200mg/L and 400-1000 mg/L berberine wastewater respectively.

  1. The criterion for time symmetry of probabilistic theories and the reversibility of quantum mechanics

    Science.gov (United States)

    Holster, A. T.

    2003-10-01

    Physicists routinely claim that the fundamental laws of physics are 'time symmetric' or 'time reversal invariant' or 'reversible'. In particular, it is claimed that the theory of quantum mechanics is time symmetric. But it is shown in this paper that the orthodox analysis suffers from a fatal conceptual error, because the logical criterion for judging the time symmetry of probabilistic theories has been incorrectly formulated. The correct criterion requires symmetry between future-directed laws and past-directed laws. This criterion is formulated and proved in detail. The orthodox claim that quantum mechanics is reversible is re-evaluated. The property demonstrated in the orthodox analysis is shown to be quite distinct from time reversal invariance. The view of Satosi Watanabe that quantum mechanics is time asymmetric is verified, as well as his view that this feature does not merely show a de facto or 'contingent' asymmetry, as commonly supposed, but implies a genuine failure of time reversal invariance of the laws of quantum mechanics. The laws of quantum mechanics would be incompatible with a time-reversed version of our universe.

  2. Reducing cholinergic constriction: the major reversible mechanism in COPD

    Directory of Open Access Journals (Sweden)

    V. Brusasco

    2006-12-01

    Full Text Available The airway narrowing in chronic obstructive pulmonary disease (COPD has often been misunderstood as being irreversible. However, a large proportion of patients with COPD do respond to bronchodilator agents with significant changes in lung function. Unlike in asthma, abnormalities in airway smooth muscle structure or function are not believed to play a key role in COPD airway narrowing. Although there are only limited data suggesting that cholinergic tone may be increased in COPD, the well-documented efficacy of antimuscarinic agents in increasing airway calibre suggests that cholinergic tone represents the major reversible component of airflow obstruction in these patients. Airway wall thickening and loss of airway-to-parenchyma interdependence are nonreversible components of airflow obstruction in COPD that may amplify the effect of changes in airway smooth muscle tone. Thus, keeping airway smooth muscle tone to a minimum might offer patients long-lasting airway patency and protection against breathlessness, which is the major complaint of patients with COPD. Receptor antagonism by anticholinergic agents can achieve effective relaxation of airway smooth muscle in COPD. According to a classical view of cholinergic receptor function and distribution, the ideal anticholinergic bronchodilator would be one that blocks both M1 and M3 receptors, which mediate airway smooth muscle contraction, but not the M2 receptor, stimulation of which reduces acetylcholine release from vagus nerve endings and prevents the airway smooth muscle from contracting by excessive increments. Agents with such pharmacodynamic selectivity are not available, but effective and prolonged inhibition of airway smooth muscle tone has been obtained with tiotropium, which binds to all three major muscarinic receptor subtypes, but for much longer to M3 than to M2 receptors. Recent data show that long-term treatment with tiotropium for 1 yr helps sustain 24-h airway patency. This

  3. A-posteriori error estimation for second order mechanical systems

    Institute of Scientific and Technical Information of China (English)

    Thomas Ruiner; J(ǒ)rg Fehr; Bernard Haasdonk; Peter Eberhard

    2012-01-01

    One important issue for the simulation of flexible multibody systems is the reduction of the flexible bodies degrees of freedom.As far as safety questions are concerned knowledge about the error introduced by the reduction of the flexible degrees of freedom is helpful and very important.In this work,an a-posteriori error estimator for linear first order systems is extended for error estimation of mechanical second order systems.Due to the special second order structure of mechanical systems,an improvement of the a-posteriori error estimator is achieved· A major advantage of the a-posteriori error estimator is that the estimator is independent of the used reduction technique.Therefore,it can be used for moment-matching based,Gramian matrices based or modal based model reduction techniques.The capability of the proposed technique is demonstrated by the a-posteriori error estimation of a mechanical system,and a sensitivity analysis of the parameters involved in the error estimation process is conducted.

  4. Kinetic Analysis of Parallel-Consecutive First-Order Reactions with a Reversible Step: Concentration-Time Integrals Method

    Science.gov (United States)

    Mucientes, A. E.; de la Pena, M. A.

    2009-01-01

    The concentration-time integrals method has been used to solve kinetic equations of parallel-consecutive first-order reactions with a reversible step. This method involves the determination of the area under the curve for the concentration of a given species against time. Computer techniques are used to integrate experimental curves and the method…

  5. Spectroscopic studies of the mechanism of reversible photodegradation of 1-substituted aminoanthraquinone-doped polymers

    Science.gov (United States)

    Hung, Sheng-Ting; Bhuyan, Ankita; Schademan, Kyle; Steverlynck, Joost; McCluskey, Matthew D.; Koeckelberghs, Guy; Clays, Koen; Kuzyk, Mark G.

    2016-03-01

    The mechanism of reversible photodegradation of 1-substituted aminoanthraquinones doped into poly(methyl methacrylate) and polystyrene is investigated. Time-dependent density functional theory is employed to predict the transition energies and corresponding oscillator strengths of the proposed reversibly and irreversibly damaged dye species. Ultraviolet-visible and Fourier transform infrared (FTIR) spectroscopy are used to characterize which species are present. FTIR spectroscopy indicates that both dye and polymer undergo reversible photodegradation when irradiated with a visible laser. These findings suggest that photodegradation of 1-substituted aminoanthraquinones doped in polymers originates from interactions between dyes and photoinduced thermally degraded polymers, and the metastable product may recover or further degrade irreversibly.

  6. Spectroscopic studies of the mechanism of reversible photodegradation of 1-substituted aminoanthraquinone-doped polymers

    CERN Document Server

    Hung, Sheng-Ting; Schademan, Kyle; Steverlynck, Joost; McCluskey, Matthew D; Koeckelberghs, Guy; Clays, Koen; Kuzyk, Mark G

    2015-01-01

    The mechanism of reversible photodegradation of 1-substituted aminoanthraquinones doped into poly(methyl methacrylate) and polystyrene is investigated. Time-dependent density functional theory is employed to predict the transition energies and corresponding oscillator strengths of the proposed reversibly- and irreversibly-damaged dye species. Ultraviolet-visible and Fourier transform infrared (FTIR) spectroscopy are used to characterize which species are present. FTIR spectroscopy indicates that both dye and polymer undergo reversible photodegradation when irradiated with a visible laser. These findings suggest that photodegradation of 1-substituted aminoanthraquinones doped in polymers originates from interactions between dyes and photoinduced thermally-degraded polymers, and the metastable product may recover or further degrade irreversibly.

  7. Spectroscopic studies of the mechanism of reversible photodegradation of 1-substituted aminoanthraquinone-doped polymers

    OpenAIRE

    Hung, Sheng-Ting; Bhuyan, Ankita; Schademan, Kyle; Steverlynck, Joost; McCluskey, Matthew D.; Koeckelberghs, Guy; Clays, Koen; Kuzyk, Mark G.

    2015-01-01

    The mechanism of reversible photodegradation of 1-substituted aminoanthraquinones doped into poly(methyl methacrylate) and polystyrene is investigated. Time-dependent density functional theory is employed to predict the transition energies and corresponding oscillator strengths of the proposed reversibly- and irreversibly-damaged dye species. Ultraviolet-visible and Fourier transform infrared (FTIR) spectroscopy are used to characterize which species are present. FTIR spectroscopy indicates t...

  8. Magnetic unmixing of first-order reversal curve diagrams using principal component analysis

    Science.gov (United States)

    Lascu, Ioan; Harrison, Richard; Li, Yuting; Piotrowski, Alexander; Channell, James; Muraszko, Joy; Hodell, David

    2015-04-01

    We have developed a magnetic unmixing method based on principal component analysis (PCA) of entire first-order reversal curve (FORC) diagrams. FORC diagrams are an advanced hysteresis technique that allows the quantitative characterisation of magnetic grain size, domain state, coercivity and spatial distribution of ensembles of particles within a sample. PCA has been previously applied on extracted central ridges from FORC diagrams of sediment samples containing single domain (SD) magnetite produced by magnetotactic bacteria (Heslop et al., 2014). We extend this methodology to the entire FORC space, which incorporates additional SD signatures, pseudo-single domain (PSD) and multi domain (MD) magnetite signatures, as well as fingerprints of other minerals, such as hematite (HEM). We apply the PCA by resampling the FORC distribution on a regular grid designed to encompass all significant features. Typically 80-90% of the variability within the FORC dataset is described by one or two principal components. Individual FORCs are recast as linear combinations of physically distinct end-member FORCs defined using the principal components and constraints derived from physical modelling. In a first case study we quantify the spatial variation of end-member components in surficial sediments along the North Atlantic Deep Water (NADW) from Iceland to Newfoundland. The samples have been physically separated into granulometric fractions, which added a further constraint in determining three end members used to model the magnetic ensemble, namely a coarse silt-sized MD component, a fine silt-sized PSD component, and a mixed clay-sized component containing both SD magnetite and hematite (SD+HEM). Sediments from core tops proximal to Iceland are dominated by the SD+HEM component, whereas those closer to Greenland and Canada are increasingly dominated by MD grains. Iceland sediments follow a PSD to SD+HEM trend with increasing grain-size fraction, whereas the Greenland and North

  9. Mechanism, time-reversal symmetry, and topology of superconductivity in noncentrosymmetric systems

    Science.gov (United States)

    Scheurer, M. S.

    2016-05-01

    We analyze the possible interaction-induced superconducting instabilities in noncentrosymmetric systems based on symmetries of the normal state. It is proven that pure electron-phonon coupling will always lead to a fully gapped superconductor that does not break time-reversal symmetry and is topologically trivial. We show that topologically nontrivial behavior can be induced by magnetic doping without gapping out the resulting Kramers pair of Majorana edge modes. In the case of superconductivity arising from the particle-hole fluctuations associated with a competing instability, the properties of the condensate crucially depend on the time-reversal behavior of the order parameter of the competing instability. When the order parameter preserves time-reversal symmetry, we obtain exactly the same properties as in the case of phonons. If it is odd under time reversal, the Cooper channel of the interaction will be fully repulsive leading to sign changes of the gap and making spontaneous time-reversal-symmetry breaking possible. To discuss topological properties, we focus on fully gapped time-reversal-symmetric superconductors and derive constraints on possible pairing states that yield necessary conditions for the emergence of topologically nontrivial superconductivity. These conditions might serve as a tool in the search for topological superconductors. We also discuss implications for oxide heterostructures and single-layer FeSe.

  10. Reversal learning in C58 mice: Modeling higher order repetitive behavior.

    Science.gov (United States)

    Whitehouse, Cristina M; Curry-Pochy, Lisa S; Shafer, Robin; Rudy, Joseph; Lewis, Mark H

    2017-08-14

    Restricted, repetitive behaviors are diagnostic for autism and prevalent in other neurodevelopmental disorders. These behaviors cluster as repetitive sensory-motor behaviors and behaviors reflecting resistance to change. The C58 mouse strain is a promising model for these behaviors as it emits high rates of aberrant repetitive sensory-motor behaviors. The purpose of the present study was to extend characterization of the C58 model to resistance to change. This was done by comparing C58 to C57BL/6 mice on a reversal learning task under either a 100% or 80%/20% probabilistic reinforcement schedule. In addition, the effect of environmental enrichment on performance of this task was assessed as this rearing condition markedly reduces repetitive sensory-motor behavior in C58 mice. Little difference was observed between C58 and control mice under a 100% schedule of reinforcement. The 80%/20% probabilistic schedule of reinforcement generated substantial strain differences, however. Importantly, no strain difference was observed in acquisition, but C58 mice were markedly impaired in their ability to reverse their pattern of responding from the previously high density reinforcement side. Environmental enrichment did not impact acquisition under the probabilistic reinforcement schedule, but enriched C58 mice performed significantly better than standard housed C58 mice in reversal learning. Thus, C58 mice exhibit behaviors that reflect both repetitive sensory motor behaviors as well as behavior that reflects resistance to change. Moreover, both clusters of repetitive behavior were attenuated by environmental enrichment. Such findings, along with the reported social deficits in C58 mice, increase the translational value of this mouse model to autism. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Oscillatory integrals and phenomena beyond all algebriac orders with applications to homoclinic orbits in reversible systems

    CERN Document Server

    Lombardi, Eric

    2000-01-01

    During the last two decades, in several branches of science (water waves, crystal growth, travelling waves in one dimensional lattices, splitting of separatrices,...) different problems appeared in which the key point is the computation of exponentially small terms. This self-contained monograph gives new and rigorous mathematical tools which enable a systematic study of such problems. Starting with elementary illuminating examples, the book contains (i) new asymptotical tools for obtaining exponentially small equivalents of oscillatory integrals involving solutions of nonlinear differential equations; (ii) implementation of these tools for solving old open problems of bifurcation theory such as existence of homoclinic connections near resonances in reversible systems.

  12. Exploration of a Novel Persistent Reversal of Pathological Pain: Mechanisms and Mediators

    Science.gov (United States)

    2015-04-01

    cultured glial cells blocked TNF and but not IL-10 production , suggesting that while PKA and PKC may play a role in A2AR agonist effects, there are also...models of neuropathic pain and to elucidate the underlying mechanisms that result in the production of IL-10 and subsequent reversal of the allodynia. 15...translated to numerous animal models of neuropathic pain and to elucidate the underlying mechanisms that result in the production of IL-10 and

  13. Limit cycles from a cubic reversible system via the third-order averaging method

    Directory of Open Access Journals (Sweden)

    Linping Peng

    2015-04-01

    Full Text Available This article concerns the bifurcation of limit cycles from a cubic integrable and non-Hamiltonian system. By using the averaging theory of the first and second orders, we show that under any small cubic homogeneous perturbation, at most two limit cycles bifurcate from the period annulus of the unperturbed system, and this upper bound is sharp. By using the averaging theory of the third order, we show that two is also the maximal number of limit cycles emerging from the period annulus of the unperturbed system.

  14. Probing the A1 to L10 transformation in FeCuPt using the first order reversal curve method

    Directory of Open Access Journals (Sweden)

    Dustin A. Gilbert

    2014-08-01

    Full Text Available The A1-L10 phase transformation has been investigated in (001 FeCuPt thin films prepared by atomic-scale multilayer sputtering and rapid thermal annealing (RTA. Traditional x-ray diffraction is not always applicable in generating a true order parameter, due to non-ideal crystallinity of the A1 phase. Using the first-order reversal curve (FORC method, the A1 and L10 phases are deconvoluted into two distinct features in the FORC distribution, whose relative intensities change with the RTA temperature. The L10 ordering takes place via a nucleation-and-growth mode. A magnetization-based phase fraction is extracted, providing a quantitative measure of the L10 phase homogeneity.

  15. Investigation of the magnetization reversal mechanism of electrolessly deposited Co-B nanotubes

    Science.gov (United States)

    Richardson, David; Kingston, Samuel; Rhen, Fernando M. F.

    2016-05-01

    Co-B nanotubes were prepared via an electroless deposition method. The morphology, magnetic properties and the magnetization reversal mechanism of the nanotubes were investigated. Deposition was carried out in porous polycarbonate membranes leading to the formation of Co-B nanotubes with an average external diameter of 400 nm and lengths up to 6 μm. Electroless deposition resulted in the formation of alloys with composition Co70B30 and a specific magnetization of 65.6 J T-1kg-1, which is about 40 % of that of pure Co (161 J T-1kg-1). The transversal and vortex modes were identified as the mechanisms responsible for magnetization reversal in the nanotubes. A crossover between the two modes is observed at low angles and the results are in line with current models for switching mechanisms of nanotubes.

  16. Investigation of the magnetization reversal mechanism of electrolessly deposited Co-B nanotubes

    Directory of Open Access Journals (Sweden)

    David Richardson

    2016-05-01

    Full Text Available Co-B nanotubes were prepared via an electroless deposition method. The morphology, magnetic properties and the magnetization reversal mechanism of the nanotubes were investigated. Deposition was carried out in porous polycarbonate membranes leading to the formation of Co-B nanotubes with an average external diameter of 400 nm and lengths up to 6 μm. Electroless deposition resulted in the formation of alloys with composition Co70B30 and a specific magnetization of 65.6 J T−1kg−1, which is about 40 % of that of pure Co (161 J T−1kg−1. The transversal and vortex modes were identified as the mechanisms responsible for magnetization reversal in the nanotubes. A crossover between the two modes is observed at low angles and the results are in line with current models for switching mechanisms of nanotubes.

  17. Reversal effect and mechanism of Ginkgo biloba exocarp extracts in multidrug resistance of mice S180 tumor cells

    Science.gov (United States)

    Hu, Bi-Yuan; Gu, Yun-Hao; Cao, Chen-Jie; Wang, Jun; Han, Dong-Dong; Tang, Ying-Chao; Chen, Hua-Sheng; Xu, Aihua

    2016-01-01

    The aim of the present study was to investigate the reversal effect and its related mechanism of Ginkgo biloba exocarp extracts (GBEEs) in obtained multidrug resistance (MDR) of mice S180 tumor cells in vitro and in vivo. In order to simulate the clinical PFC [cis-dichlorodiamineplatinum, cisplatin (DDP) + fluorouracil (FU), FU+cyclophosphamide and cyclophosphamide] scheme, a gradually increasing dose was administered in a phased induction in order to induce S180 cells in vivo and to make them obtain multidrug resistance. The results in vitro demonstrated that GBEE could significantly increase the IC50 of DDP on S180 MDR cells, increase the accumulation of Adriamycin (ADR) and rhodamine 123 (Rho 123), and reduce the efflux of Rho 123 of S180 MDR cells. The results from the in vivo treatment with a combination of GBEE and DDP to S180 MDR ascites tumor in mice demonstrated that each dose of GBEE could effectively reverse the drug-resistance of S180 MDR cells to DDP in order to extend the survival time of mice with ascite tumors and inhibit tumor growth in solid tumor mice. In addition, GBEE effectively inhibited the expression of MDR-1 mRNA and multidrug resistance-associated protein-1 mRNA in S180 MDR cells of ascites tumor in mice and improved the expression levels of cytokines, including interleukin (IL)-3, IL-18 and interferon-γ in the blood serum of S180 MDR tumor-bearing mice. The present study showed that the mechanism of GBEE reversal of MDR may be associated with the inhibition of the functional activity of P-glycoprotein, the downregulation of drug resistance related gene expression of S180 MDR cells and the improvement of the production of related serum cytokines of S180 MDR tumor mice. PMID:27698692

  18. Reversal effect and mechanism of Ginkgo biloba exocarp extracts in multidrug resistance of mice S180 tumor cells.

    Science.gov (United States)

    Hu, Bi-Yuan; Gu, Yun-Hao; Cao, Chen-Jie; Wang, Jun; Han, Dong-Dong; Tang, Ying-Chao; Chen, Hua-Sheng; Xu, Aihua

    2016-10-01

    The aim of the present study was to investigate the reversal effect and its related mechanism of Ginkgo biloba exocarp extracts (GBEEs) in obtained multidrug resistance (MDR) of mice S180 tumor cells in vitro and in vivo. In order to simulate the clinical PFC [cis-dichlorodiamineplatinum, cisplatin (DDP) + fluorouracil (FU), FU+cyclophosphamide and cyclophosphamide] scheme, a gradually increasing dose was administered in a phased induction in order to induce S180 cells in vivo and to make them obtain multidrug resistance. The results in vitro demonstrated that GBEE could significantly increase the IC50 of DDP on S180 MDR cells, increase the accumulation of Adriamycin (ADR) and rhodamine 123 (Rho 123), and reduce the efflux of Rho 123 of S180 MDR cells. The results from the in vivo treatment with a combination of GBEE and DDP to S180 MDR ascites tumor in mice demonstrated that each dose of GBEE could effectively reverse the drug-resistance of S180 MDR cells to DDP in order to extend the survival time of mice with ascite tumors and inhibit tumor growth in solid tumor mice. In addition, GBEE effectively inhibited the expression of MDR-1 mRNA and multidrug resistance-associated protein-1 mRNA in S180 MDR cells of ascites tumor in mice and improved the expression levels of cytokines, including interleukin (IL)-3, IL-18 and interferon-γ in the blood serum of S180 MDR tumor-bearing mice. The present study showed that the mechanism of GBEE reversal of MDR may be associated with the inhibition of the functional activity of P-glycoprotein, the downregulation of drug resistance related gene expression of S180 MDR cells and the improvement of the production of related serum cytokines of S180 MDR tumor mice.

  19. Small-molecule inhibition of STOML3 oligomerization reverses pathological mechanical hypersensitivity.

    Science.gov (United States)

    Wetzel, Christiane; Pifferi, Simone; Picci, Cristina; Gök, Caglar; Hoffmann, Diana; Bali, Kiran K; Lampe, André; Lapatsina, Liudmila; Fleischer, Raluca; Smith, Ewan St John; Bégay, Valérie; Moroni, Mirko; Estebanez, Luc; Kühnemund, Johannes; Walcher, Jan; Specker, Edgar; Neuenschwander, Martin; von Kries, Jens Peter; Haucke, Volker; Kuner, Rohini; Poulet, James F A; Schmoranzer, Jan; Poole, Kate; Lewin, Gary R

    2017-02-01

    The skin is equipped with specialized mechanoreceptors that allow the perception of the slightest brush. Indeed, some mechanoreceptors can detect even nanometer-scale movements. Movement is transformed into electrical signals via the gating of mechanically activated ion channels at sensory endings in the skin. The sensitivity of Piezo mechanically gated ion channels is controlled by stomatin-like protein-3 (STOML3), which is required for normal mechanoreceptor function. Here we identify small-molecule inhibitors of STOML3 oligomerization that reversibly reduce the sensitivity of mechanically gated currents in sensory neurons and silence mechanoreceptors in vivo. STOML3 inhibitors in the skin also reversibly attenuate fine touch perception in normal mice. Under pathophysiological conditions following nerve injury or diabetic neuropathy, the slightest touch can produce pain, and here STOML3 inhibitors can reverse mechanical hypersensitivity. Thus, small molecules applied locally to the skin can be used to modulate touch and may represent peripherally available drugs to treat tactile-driven pain following neuropathy.

  20. Viral fitness: relation to drug resistance mutations and mechanisms involved: nucleoside reverse transcriptase inhibitor mutations.

    Science.gov (United States)

    Weber, Jan; Henry, Kenneth R; Arts, Eric J; Quiñones-Mateu, Miguel E

    2007-03-01

    Nucleoside and nucleotide reverse transcriptase inhibitors constitute the backbone of highly active antiretroviral therapy in the treatment of HIV-1 infection. One of the major obstacles in achieving the long-term efficacy of anti-HIV-1 therapy is the development of resistance. The advent of resistance mutations is usually accompanied by a change in viral replicative fitness. This review focuses on the most common nucleoside reverse transcriptase inhibitor-associated mutations and their effects on HIV-1 replicative fitness. Recent studies have explained the two main mechanisms of resistance to nucleoside reverse transcriptase inhibitors and their role in HIV-1 replicative fitness. The first involves mutations directly interfering with binding or incorporation and seems to impact replicative fitness more adversely than the second mechanism, which involves enhanced excision of the newly incorporated analogue. Further studies have helped explain the antagonistic effects between amino acid substitutions, K65R, L74V, M184V, and thymidine analogue mutations, showing how viral replicative fitness influences the evolution of thymidine analogue resistance pathways. Nucleoside reverse transcriptase inhibitor resistance mutations impact HIV-1 replicative fitness to a lesser extent than protease resistance mutations. The monitoring of viral replicative fitness may help in the management of HIV-1 infection in highly antiretroviral-experienced individuals.

  1. Low-temperature first-order reversal curves and interaction effects on assemblies of iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhijun [Functional Nanomaterials Group, Industrial Materials Institute, National Research Council Canada, 75 de Mortagne Boulevard, Boucherville, QC, J4B 6Y4 (Canada); Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, 398 Ruoshui Road, Dushu Lake Higher Education District, Suzhou Industrial Park, Suzhou, 215125 (China); Clime, Liviu [Functional Nanomaterials Group, Industrial Materials Institute, National Research Council Canada, 75 de Mortagne Boulevard, Boucherville, QC, J4B 6Y4 (Canada); Tomanek, Boguslaw [Institute for Biodiagnostics (West), National Research Council Canada, 3330 Hospital Dr NW, Calgary, Alberta, T2N 4N1 (Canada); Department of Clinical Neurosciences, University of Calgary, 1403 - 29th Street N.W., Alberta, T2N 4N1 (Canada); Sutherland, Garnette [Department of Clinical Neurosciences, University of Calgary, 1403 - 29th Street N.W., Alberta, T2N 4N1 (Canada); Veres, Teodor, E-mail: Teodor.Veres@nrc.c [Functional Nanomaterials Group, Industrial Materials Institute, National Research Council Canada, 75 de Mortagne Boulevard, Boucherville, QC, J4B 6Y4 (Canada); Energie, Materiaux et Telecommunications, Institut national de la recherche scientifique, Universite du Quebec, 1650 boulevard Lionel-Boulet, Varennes, Quebec, J3X 1S2 (Canada)

    2009-11-01

    We present the synthesis and magnetic properties of high quality uncoated and gold-coated iron oxide magnetic nanoparticles. The structural properties of these nanoparticles are investigated by transmission electron microscopy, UV-visible spectroscopy and X-ray diffraction. Experimental results and theoretical simulations indicate that the synthesized nanoparticles present a very good monodispersity, and well defined size and shape. The coercive field of these particles is identified by low-temperature first-order reversal curves and the results used in order to fit zero-field-cooled magnetization processes with theoretical models. The identification of the parameters in this analysis suggests that the coating process hardly affects the morphology and the overall magnetic properties of the cores inside coated particles.

  2. First-Order Acoustic Wave Equation Reverse Time Migration Based on the Dual-Sensor Seismic Acquisition System

    Science.gov (United States)

    You, Jiachun; Liu, Xuewei; Wu, Ru-Shan

    2017-03-01

    We analyze the mathematical requirements for conventional reverse time migration (RTM) and summarize their rationale. The known information provided by current acquisition system is inadequate for the second-order acoustic wave equations. Therefore, we introduce a dual-sensor seismic acquisition system into the coupled first-order acoustic wave equations. We propose a new dual-sensor reverse time migration called dual-sensor RTM, which includes two input variables, the pressure and vertical particle velocity data. We focus on the performance of dual-sensor RTM in estimating reflection coefficients compared with conventional RTM. Synthetic examples are used for the study of estimating coefficients of reflectors with both dual-sensor RTM and conventional RTM. The results indicate that dual-sensor RTM with two inputs calculates amplitude information more accurately and images structural positions of complex substructures, such as the Marmousi model, more clearly than that of conventional RTM. This shows that the dual-sensor RTM has better accuracy in backpropagation and carries more information in the directivity because of particle velocity injection. Through a simple point-shape model, we demonstrate that dual-sensor RTM decreases the effect of multi-pathing of propagating waves, which is helpful for focusing the energy. In addition, compared to conventional RTM, dual-sensor RTM does not cause extra memory costs. Dual-sensor RTM is, therefore, promising for the computation of multi-component seismic data.

  3. A Study on Efficient Mobile IPv6 Fast Handover Scheme Using Reverse Binding Mechanism

    Science.gov (United States)

    Tolentino, Randy S.; Lee, Kijeong; Kim, Sung-Gyu; Kim, Miso; Park, Byungjoo

    This paper proposes a solution for solving the packet handover issues of MIPv6. We propose an efficient scheme that can support fast handover effectively in standard Mobile IPv6 (MIPv6) by optimizing the associated data and the flow of signal during handover. A new signaling message Reverse Packet Binding Mechanism is defined and utilized to hasten the handover procedure by adding a buffer in access point (AP) and home agent (HA).

  4. 46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order...

  5. Asymmetric effect of mechanical stress on the forward and reverse reaction catalyzed by an enzyme.

    Directory of Open Access Journals (Sweden)

    Collin Joseph

    Full Text Available The concept of modulating enzymatic activity by exerting a mechanical stress on the enzyme has been established in previous work. Mechanical perturbation is also a tool for probing conformational motion accompanying the enzymatic cycle. Here we report measurements of the forward and reverse kinetics of the enzyme Guanylate Kinase from yeast (Saccharomyces cerevisiae. The enzyme is held in a state of stress using the DNA spring method. The observation that mechanical stress has different effects on the forward and reverse reaction kinetics suggests that forward and reverse reactions follow different paths, on average, in the enzyme's conformational space. Comparing the kinetics of the stressed and unstressed enzyme we also show that the maximum speed of the enzyme is comparable to the predictions of the relaxation model of enzyme action, where we use the independently determined dissipation coefficient [Formula: see text] for the enzyme's conformational motion. The present experiments provide a mean to explore enzyme kinetics beyond the static energy landscape picture of transition state theory.

  6. Reversible and irreversible emergence of chiroptical signals in J-aggregates of achiral 4-sulfonatophenyl substituted porphyrins: intrinsic chirality vs. chiral ordering in the solution.

    Science.gov (United States)

    Arteaga, Oriol; El-Hachemi, Zoubir; Canillas, Adolf; Crusats, Joaquim; Rovira, Meritxell; Ribó, Josep M

    2016-09-18

    Mueller matrix polarimetry distinguishes the different origins of the reversible and irreversible chiroptical effects emerging in stirred solutions of J-aggregate nanoparticles: the reversible effect is due to an anisotropic ordering in the solution and the irreversible one is due to a bias from the racemic composition of intrinsically chiral structures.

  7. Reverse saturable absorption studies in polymerized indole - Effect of polymerization in the phenomenal enhancement of third order optical nonlinearity

    Science.gov (United States)

    Jayakrishnan, K.; Joseph, Antony; Bhattathiripad, Jayakrishnan; Ramesan, M. T.; Chandrasekharan, K.; Siji Narendran, N. K.

    2016-04-01

    We report our results on the identification of large order enhancement in nonlinear optical coefficients of polymerized indole and its comparative study with reference to its monomer counterpart. Indole monomer shows virtually little third order effects whereas its polymerized version exhibits phenomenal increase in its third order nonlinear optical parameters such as nonlinear refractive index and nonlinear absorption. Open aperture Z-scan trace of polyindole done with Q-switched Nd:YAG laser source (532 nm, 7 ns), shows β value as high as 89 cm/GW at a beam energy of 0.83 GW/cm2. Closed aperture Z-scan done at identical energies reveals nonlinear refractive index of the order of -3.55 × 10-17 m2/W. Band gap measurement of polyindole was done with UV-Vis absorption spectra and compared with that of Indole. FTIR spectra of the monomer and polymerized versions were recorded and relevant bond formations were confirmed from the characteristic peaks. Photo luminescent spectra were investigated to know the emission features of both molecules. Beam energy (I0) versus nonlinear absorption coefficient (β) plot indicates reverse saturable type of absorption behaviour in polyindole molecules. Degenerate Four Wave Mixing (DFWM) plot of polyindole reveals quite a cubic dependence between probe and phase conjugate signal and the resulting χ(3) is comparable with Z-scan results. Optical limiting efficiency of polyindole is comparable with certain derivatives of porphyrins, phthalocyanines and graphene oxides.

  8. FORCinel Version 3.0: An Integrated Environment for Processing, Analysis and Simulation of First-Order Reversal Curve Diagrams

    Science.gov (United States)

    Lascu, I.; Harrison, R. J.

    2016-12-01

    First-order reversal curve (FORC) diagrams are a powerful method to characterise the hysteresis properties of magnetic grain ensembles. Methods of processing, analysis and simulation of FORC diagrams have developed rapidly over the past few years, dramatically expanding their utility within rock magnetic research. Here we announce the latest release of FORCinel (Version 3.0), which integrates many of these developments into a unified, user-friendly package running within Igor Pro (www.wavemetrics.com). FORCinel v. 3.0 can be downloaded from https://wserv4.esc.cam.ac.uk/nanopaleomag/. The release will be accompanied by a series of video tutorials outlining each of the new features, including: i) improved work flow, with unified smoothing approach; ii) increased processing speed using multiple processors; iii) control of output resolution, enabling large datasets (> 500 FORCs) to be smoothed in a matter of seconds; iv) load, process, analyse and average multiple FORC diagrams; v) load and process non-gridded data and data acquired on non-PMC systems; vi) improved method for exploring optimal smoothing parameters; vii) interactive and un-doable data-pretreatments; viii) automated detection and removal of measurement outliers; ix) improved interactive method for the generation and optimisation of colour scales; x) full integration with FORCem1 - supervised quantitative unmixing of FORC diagrams using principle component analysis (PCA); xi) full integration with FORCulator2 - micromagnetic simulation of FORC diagrams; xiii) simulate TRM acquisition using the kinetic Monte Carlo simulation algorithm of Shcherbakov3. 1. Lascu, I., Harrison, R.J., Li, Y., Muraszko, J.R., Channell, J.E.T., Piotrowski, A.M., Hodell, D.A., 2015. Magnetic unmixing of first-order reversal curve diagrams using principal component analysis. Geochemistry, Geophys. Geosystems 16, 2900-2915. 2. Harrison, R.J., Lascu, I., 2014. FORCulator: A micromagnetic tool for simulating first-order reversal

  9. Mechanism of Cyclically Polarity Reversing Solar Magnetic Cycle as a Cosmic Dynamo

    Indian Academy of Sciences (India)

    Hirokazu Yoshimura

    2000-09-01

    We briefly describe historical development of the concept of solar dynamo mechanism that generates electric current and magnetic field by plasma flows inside the solar convection zone. The dynamo is the driver of the cyclically polarity reversing solar magnetic cycle. The reversal process can easily and visually be understood in terms of magnetic field line stretching and twisting and folding in three-dimensional space by plasma flows of differential rotation and global convection under influence of Coriolis force. This process gives rise to formation of a series of huge magnetic flux tubes that propagate along iso-rotation surfaces inside the convection zone. Each of these flux tubes produces one solar cycle. We discuss general characteristics of any plasma flows that can generate magnetic field and reverse the polarity of the magnetic field in a rotating body in the Universe. We also mention a list of problems which are currently being disputed concerning the solar dynamo mechanism together with observational evidences that are to be constraints as well as verifications of any solar cycle dynamo theories of short and long term behaviors of the Sun, particularly time variations of its magnetic field, plasma flows, and luminosity.

  10. Mechanisms of reversible photodegradation in disperse orange 11 dye doped in PMMA polymer

    CERN Document Server

    Embaye, Natnael B; Kuzyk, Mark G

    2008-01-01

    We use amplified spontaneous emission (ASE) and linear absorption spectroscopy to study the mechanisms of reversible photodegradation of 1-amino-2-methylanthraquinone (disperse orange 11-DO11) in solid poly(methyl methacrylate). Measurements as a function of intensity, concentration, and time suggest that ASE originates in a state (be it a tautomer or a vibronic level) that can form a dimer or some other aggregate upon relaxation, which through fluorescence quenching leads to degradation of the ASE signal. Whatever the degradation route, a high concentration of DO11 is required and the polymer plays a key role in the process of opening a new reversible degradation pathway that is not available at lower concentrations or in liquid solutions. We construct an energy level diagram that describes all measured quantities in the decay and recovery processes and propose a hypothesis of the nature of the associated states.

  11. Preparation and formation mechanism of Al2O3 nanoparticles by reverse microemulsion

    Institute of Scientific and Technical Information of China (English)

    HUANG Ke-long; YIN Liang-guo; LIU Su-qin; LI Chao-jian

    2007-01-01

    Al2O3 nanoparticles were prepared by polyethylene glycol octylphenyl ether(Triton X-100)/n-butyl alcohol/cyclohexane/ water W/O reverse microemulsion. The proper calcination temperature was determined at 1 150 ℃ by thermal analysis of the precursor products. The structures and morphologies of Al2O3 nanoparticles were characterized by X-ray diffraction, transmission electron microscopy and UV-Vis spectra. The influences of mole ratio of water to surfactant on the morphologies and the sizes of the Al2O3 nanoparticles were studied. With the increase of surfactant content, the particles size becomes larger. The agglomeration of nanoparticles was solved successfully. And the formation mechanisms of Al2O3 nanoparticles in the reverse microemulsion were also discussed.

  12. A Dynamic Pricing Reverse Auction-Based Resource Allocation Mechanism in Cloud Workflow Systems

    Directory of Open Access Journals (Sweden)

    Xuejun Li

    2016-01-01

    Full Text Available Market-oriented reverse auction is an efficient and cost-effective method for resource allocation in cloud workflow systems since it can dynamically allocate resources depending on the supply-demand relationship of the cloud market. However, during the auction the price of cloud resource is usually fixed, and the current resource allocation mechanisms cannot adapt to the changeable market properly which results in the low efficiency of resource utilization. To address such a problem, a dynamic pricing reverse auction-based resource allocation mechanism is proposed. During the auction, resource providers can change prices according to the trading situation so that our novel mechanism can increase the chances of making a deal and improve efficiency of resource utilization. In addition, resource providers can improve their competitiveness in the market by lowering prices, and thus users can obtain cheaper resources in shorter time which would decrease monetary cost and completion time for workflow execution. Experiments with different situations and problem sizes are conducted for dynamic pricing-based allocation mechanism (DPAM on resource utilization and the measurement of Time⁎Cost (TC. The results show that our DPAM can outperform its representative in resource utilization, monetary cost, and completion time and also obtain the optimal price reduction rates.

  13. Analysis of switching properties of porous ferroelectric ceramics by means of first-order reversal curve diagrams

    Science.gov (United States)

    Stoleriu, Laurentiu; Stancu, Alexandru; Mitoseriu, Liliana; Piazza, Daniele; Galassi, Carmen

    2006-11-01

    Particular aspects of the switching properties of the Nb-PZT ceramics with anisotropic porosity (40% relative porosity) were investigated by comparison with the dense ceramics (5% relative porosity) of the same composition by means of the first-order reversal curve (FORC) analysis. The reversible/irreversible components give different contributions to the total polarization: A sharp FORC distribution with an almost negligible reversible component is characteristic to the dense material, while a broad distribution with an important reversible component is characteristic for the porous one. The coercivity corresponding to the maximum of the irreversible component is the same irrespective to the sample density and pore’s configuration with respect to the electrodes: Ec,M=1.5kV/mm , while the bias fields are zero for the dense ceramic, small and positive; Ebias,M=50V/mm , when the major axis of the elongated pores is parallel with the electrodes and negative; Ebias,M=-100V/mm , when this axis is perpendicular to the electrodes. The influence of the dipolar coupling leading to such bias fields is explained by considering that the particular microstructure is causing a symmetry breaking, decoupling the dipolar interaction (forward or laterally). A dipolar (discrete) model with random orientations of the dipoles’ directions was used to simulate this confinement effect. The calculated FORC diagrams lead to the same type of bias as the experimental ones, proving that the lateral confinement gives an intrinsic contribution to the biased P(E) loops observed for the porous ceramics. In addition with other possible extrinsic contributions, this dipolar coupling can be a source of the built-in field in confined ferroelectric structures. The experimental FORC distribution was used as input in a Preisach-type model to recompose the major and symmetric minor hysteresis loops and a remarkable agreement with the experimental data was obtained. The FORC method proves to be an

  14. The Reversal Effect and Its Mechanisms of Tetramethylpyrazine on Multidrug Resistance in Human Bladder Cancer.

    Directory of Open Access Journals (Sweden)

    Shanshan Wang

    Full Text Available Chemotherapy is an important strategy for the treatment of bladder cancer. However, the main problem limiting the success of chemotherapy is the development of multidrug resistance (MDR. To improve the management of bladder cancer, it is an urgent matter to search for strategies to reverse MDR. We chose three kinds of herbal medicines including ginsenoside Rh2, (--Epigallocatechin gallate (EGCG and Tetramethylpyrazine (TMP to detect their effects on bladder cancer. Reversal effects of these three herbal medicines for drug resistance in adriamycin (ADM-resistant Pumc-91 cells (Pumc-91/ADM were assessed by Cell Counting Kit-8 (CCK-8 cell proliferation assay system. The mechanisms of reversal effect for TMP were explored in Pumc-91/ADM and T24/DDP cells. After Pumc-91/ADM and T24/DDP cells were treated with TMP, cell cycle distribution analysis was performed by flow cytometry. The expression of MRP1, GST, BCL-2, LRP and TOPO-II was evaluated using quantitative real-time polymerase chain reaction (qRT-PCR, immunefluorescence assay and western blot. It was observed that TMP was capable of enhancing the cytotoxicity of anticancer agents on Pumc-91/ADM cells in response to ADM, however Rh2 and EGCG were unable to. The reversal effect of TMP was also demonstrated in T24/DDP cells. Moreover, the treatment with TMP in Pumc-91/ADM and T24/DDP cells led to an increased of G1 phase accompanied with a concomitant decrease of cell numbers in S phase. Compared to the control group, an obvious decrease of MRP1, GST, BCL-2 and an increase of TOPO-II were shown in TMP groups with a dose-dependency in mRNA and protein levels. However, there was no difference on LRP expression between TMP groups and the control group. TMP could effectively reverse MDR of Pumc-91/ADM and T24/DDP cells and its mechanisms might be correlated with the alteration of MRP1, GST, BCL-2 and TOPO-II. TMP might be a potential candidate for reversing drug resistance in bladder cancer

  15. First order reversal curves and intrinsic parameter determination for magnetic materials; limitations of hysteron-based approaches in correlated systems

    Science.gov (United States)

    Ruta, Sergiu; Hovorka, Ondrej; Huang, Pin-Wei; Wang, Kangkang; Ju, Ganping; Chantrell, Roy

    2017-03-01

    The generic problem of extracting information on intrinsic particle properties from the whole class of interacting magnetic fine particle systems is a long standing and difficult inverse problem. As an example, the Switching Field Distribution (SFD) is an important quantity in the characterization of magnetic systems, and its determination in many technological applications, such as recording media, is especially challenging. Techniques such as the first order reversal curve (FORC) methods, were developed to extract the SFD from macroscopic measurements. However, all methods rely on separating the contributions to the measurements of the intrinsic SFD and the extrinsic effects of magnetostatic and exchange interactions. We investigate the underlying physics of the FORC method by applying it to the output predictions of a kinetic Monte-Carlo model with known input parameters. We show that the FORC method is valid only in cases of weak spatial correlation of the magnetisation and suggest a more general approach.

  16. First order reversal curves and intrinsic parameter determination for magnetic materials; limitations of hysteron-based approaches in correlated systems

    Science.gov (United States)

    Ruta, Sergiu; Hovorka, Ondrej; Huang, Pin-Wei; Wang, Kangkang; Ju, Ganping; Chantrell, Roy

    2017-01-01

    The generic problem of extracting information on intrinsic particle properties from the whole class of interacting magnetic fine particle systems is a long standing and difficult inverse problem. As an example, the Switching Field Distribution (SFD) is an important quantity in the characterization of magnetic systems, and its determination in many technological applications, such as recording media, is especially challenging. Techniques such as the first order reversal curve (FORC) methods, were developed to extract the SFD from macroscopic measurements. However, all methods rely on separating the contributions to the measurements of the intrinsic SFD and the extrinsic effects of magnetostatic and exchange interactions. We investigate the underlying physics of the FORC method by applying it to the output predictions of a kinetic Monte-Carlo model with known input parameters. We show that the FORC method is valid only in cases of weak spatial correlation of the magnetisation and suggest a more general approach. PMID:28338056

  17. Analysis of first order reversal curves in the thermal hysteresis of spin-crossover nanoparticles within the mechanoelastic model

    Energy Technology Data Exchange (ETDEWEB)

    Stoleriu, Laurentiu, E-mail: lstoler@uaic.ro, E-mail: cristian.enachescu@uaic.ro; Stancu, Alexandru; Enachescu, Cristian, E-mail: lstoler@uaic.ro, E-mail: cristian.enachescu@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University, 700506 Iasi (Romania); Chakraborty, Pradip; Hauser, Andreas [Département de Chimie Physique, Université de Genève, Geneva, CH-1211 (Switzerland)

    2015-05-07

    The recently obtained spin-crossover nanoparticles are possible candidates for applications in the recording media industry as materials for data storage, or as pressure and temperature sensors. For these applications, the intermolecular interactions and interactions between spin-crossover nanoparticles are extremely important, as they may be essential factors in triggering the transition between the two stable phases: the high-spin and low-spin ones. In order to find correlations between the distributions in size and interactions and the transition temperatures distribution, we apply the FORC (First Order Reversal Curves) method, using simulations based on a mechanoelastic model applied to 2D triangular lattices composed of molecules linked by springs and embedded in a surfactant. We consider two Gaussian distributions: one is the size of the nanoparticles and another is the elastic interactions between edge spin-crossover molecules and the surfactant molecules. In order to disentangle the kinetic and non-kinetic parts of the FORC distributions, we compare the results obtained for different temperature sweeping rates. We also show that the presence of few larger particles in a distribution centered around much smaller particles dramatically increases the hysteresis width.

  18. Mechanical stability of ordered droplet packings in microfluidic channels

    Science.gov (United States)

    Fleury, Jean-Baptiste; Claussen, Ohle; Herminghaus, Stephan; Brinkmann, Martin; Seemann, Ralf

    2011-12-01

    The mechanical response and stability of one and two-row packing of monodisperse emulsion droplets are studied in quasi 2d microchannels under longitudinal compression. Depending on the choice of parameter, a considered droplet arrangement is either transformed continuously into another packing under longitudinal compression or becomes mechanically unstable and segregates into domains of higher and lower packing fraction. Our experimental results are compared to analytical calculations for 2d-droplet arrangements with good quantitative agreement. This study also predicts important consequences for the stability of droplet arrangements in flowing systems.

  19. The third-order Lagrange equation for mechanical systems of variable mass

    Institute of Scientific and Technical Information of China (English)

    Ma Shan-Jun; Ge Wei-Guo; Huang Pei-Tian

    2005-01-01

    In this paper, based on the third-order D'Alembert-Lagrange principle for mechanical systems of variable mass,the third-order Lagrange equations of mechanical systems of variable mass are obtained From the equations the motion of mechanical systems of variable mass can be studied. In addition, the equations may enrich the theory of third-order differential equation.

  20. Structural and Mechanical Hysteresis at the Order-Order Transition of Block Copolymer Micellar Crystals

    Directory of Open Access Journals (Sweden)

    Theresa A. LaFollette

    2011-01-01

    Full Text Available Concentrated solutions of a water-soluble block copolymer (PEO20-(PPO70-(PEO20 show a thermoreversible transition from a liquid to a gel. Over a range of concentration there also exists an order-order transition (OOT between cubically-packed spherical micelles and hexagonally-packed cylindrical micelles. This OOT displays a hysteresis between the heating and cooling transitions that is observed at both the macroscale through rheology and nanoscale through small angle neutron scattering (SANS. The hysteresis is caused by the persistence of the cubically-packed spherical micelle phase into the hexagonally-packed cylindrical micelle phase likely due to the hindered realignment of the spherical micelles into cylindrical micelles and then packing of the cylindrical micelles into a hexagonally-packed cylindrical micelle phase. This type of hysteresis must be fully characterized, and possibly avoided, for these block copolymer systems to be used as templates in nanocomposites.

  1. Isoflurane reversibly destabilizes hippocampal dendritic spines by an actin-dependent mechanism.

    Directory of Open Access Journals (Sweden)

    Jimcy Platholi

    Full Text Available General anesthetics produce a reversible coma-like state through modulation of excitatory and inhibitory synaptic transmission. Recent evidence suggests that anesthetic exposure can also lead to sustained cognitive dysfunction. However, the subcellular effects of anesthetics on the structure of established synapses are not known. We investigated effects of the widely used volatile anesthetic isoflurane on the structural stability of hippocampal dendritic spines, a postsynaptic structure critical to excitatory synaptic transmission in learning and memory. Exposure to clinical concentrations of isoflurane induced rapid and non-uniform shrinkage and loss of dendritic spines in mature cultured rat hippocampal neurons. Spine shrinkage was associated with a reduction in spine F-actin concentration. Spine loss was prevented by either jasplakinolide or cytochalasin D, drugs that prevent F-actin disassembly. Isoflurane-induced spine shrinkage and loss were reversible upon isoflurane elimination. Thus, isoflurane destabilizes spine F-actin, resulting in changes to dendritic spine morphology and number. These findings support an actin-based mechanism for isoflurane-induced alterations of synaptic structure in the hippocampus. These reversible alterations in dendritic spine structure have important implications for acute anesthetic effects on excitatory synaptic transmission and synaptic stability in the hippocampus, a locus for anesthetic-induced amnesia, and have important implications for anesthetic effects on synaptic plasticity.

  2. The mechanism for large-volume fluid pumping via reversible snap-through of dielectric elastomer

    Science.gov (United States)

    Li, Zhe; Wang, Yingxi; Foo, Choon Chiang; Godaba, Hareesh; Zhu, Jian; Yap, Choon Hwai

    2017-08-01

    Giant deformation of dielectric elastomers (DEs) via electromechanical instability (or the "snap-through" phenomenon) is a promising mechanism for large-volume fluid pumping. Snap-through of a DE membrane coupled with compressible air has been previously investigated. However, the physics behind reversible snap-through of a DE diaphragm coupled with incompressible fluid for the purpose of fluid pumping has not been well investigated, and the conditions required for reversible snap-through in a hydraulic system are unknown. In this study, we have proposed a concept for large-volume fluid pumping by harnessing reversible snap-through of the dielectric elastomer. The occurrence of snap-through was theoretically modeled and experimentally verified. Both the theoretical and experimental pressure-volume curves of the DE membrane under different actuation voltages were used to design the work loop of the pump, and the theoretical work loop agreed with the experimental work loop. Furthermore, the feasibility of reversible snap-through was experimentally verified, and specific conditions were found necessary for this to occur, such as a minimum actuation voltage, an optimal range of hydraulic pressure exerted on the DE membrane and a suitable actuation frequency. Under optimal working conditions, we demonstrated a pumping volume of up to 110 ml per cycle, which was significantly larger than that without snap-through. Furthermore, we have achieved fluid pumping from a region of low pressure to another region of high pressure. Findings of this study would be useful for real world applications such as the blood pump.

  3. An improved algorithm for calculating first-order reversal curve (FORC) distributions using locally-weighted regression smoothing

    Science.gov (United States)

    Harrison, R. J.; Feinberg, J. M.

    2007-12-01

    First-order reversal curves (FORCs) are a powerful method for characterizing the magnetic hysteresis properties of natural and synthetic materials, and are rapidly becoming a standard tool in rock magnetic and paleomagnetic investigations. Here we describe a modification to existing algorithms for the calculation of FORC diagrams using locally-weighted regression smoothing (often referred to as loess smoothing). Like conventional algorithms, the FORC distribution is calculated by fitting a second degree polynomial to a region of FORC space defined by a smoothing factor, N. Our method differs from conventional algorithms in two ways. Firstly, rather than a square of side (2N+1) centered on the point of interest, the region of FORC space used for fitting is defined as a span of arbitrary shape encompassing the (2N+1)2 data points closest to the point of interest. Secondly, data inside the span are given a weight that depends on their distance from the point being evaluated: data closer to the point being evaluated have higher weights and have a greater effect on the fit. Loess smoothing offers two advantages over current methods. Firstly, it allows the FORC distribution to be calculated using a constant smoothing factor all the way to the Hc = 0 axis. This eliminates possible distortions to the FORC distribution associated with reducing the smoothing factor close to the Hc = 0 axis, and does not require use of the extended FORC formalism and the reversible ridge, which swamps the low-coercivity signal. Secondly, it allows finer control over the degree of smoothing applied to the data, enabling automated selection of the optimum smoothing factor for a given FORC measurement, based on an analysis of the standard deviation of the fit residuals. The new algorithm forms the basis for FORCinel, a new suite of FORC analysis tools for Igor Pro (www.wavemetrics.com), freely available on request from the authors.

  4. Mechanism of High-Order Harmonic Generation from Periodic Potentials

    CERN Document Server

    Du, Tao-Yuan

    2016-01-01

    We study numerically the Bloch electron wave-packet dynamics in periodic potentials to simulate laser-solid interactions. We introduce a quasi-classical model in the \\emph{k} space combined with the energy band structure to understand the high-order harmonic generation (HHG) process occurring in a subcycle timescale. This model interprets the multiple plateau structure in HHG spectra well and the linear dependence of cutoff energies on the amplitude of vector potential of the laser fields. It also predicts the emission time of HHG, which agrees well with the results by solving the time-dependent Schr\\"{o}dinger equation (TDSE). It provides a scheme to reconstruct the energy dispersion relations in Brillouin zone and to control the trajectories of HHG by varying the shape of laser pulses. This model is instructive for experimental measurements.

  5. Molecular mechanism of carvedilol in attenuating the reversion to fetal energy metabolism during cardiac hypertrophy development

    Institute of Scientific and Technical Information of China (English)

    胡琴; 李隆贵

    2003-01-01

    Objective: To explore the molecular regulation mechanism of carvedilol in attenuating the reversion back towards fetal energy metabolism during the development of cardiac hypertrophy induced by coarctation of abdominal aorta (CAA) in male Wistar rats. Methods: Hemodynamic and ventricular remodeling parameters, free fatty acid content in the serum were measured in the experimental animals at 16 weeks after the surgical CAA, the rats receiving carvedilol intervention (CAR) after CAA, and those with sham operation (SH). The expressions of muscle carnitine palmitoyltransferaseⅠ (M-CPTⅠ) and medium chain acyl-CoA dehydrogenase (MCAD) mRNA in the cardiac myocytes from every group were studied with RT-PCR. Results: Significant left ventricular hypertrophy were observed in the rats 16 weeks after coarctation operation (P<0.05), together with significant free fatty acids accumulation and downregulation of M-CPTⅠ and MCAD mRNA (P<0.05) in CAA group. Carvedilol at a dose of 30 mg/kg/d for 12 weeks inhibited the left ventricular hypertrophy induced by pressure overload and enhanced the gene expressions of rate-limiting enzyme (M-CPTⅠ) and key enzyme of fatty acid (MCAD) in the CAR group compared with CAA group (P<0.05). Conclusion: Pressure overload-induced hypertrophy in CAA rats causes the reversion back towards fetal enery metabolism, that is, downregulates the expressions of rate-limiting enzyme and key enzyme of fatty acid oxidation. The intervention therapy with carvedilol, a vasodilating alpha- and beta-adrenoreceptor antagonist, attenuates the reversion of the metabolic gene expression to fetal type through upregulating M-CPTⅠ and MCAD mRNA expressions. Thus, carvedilol may exert cardioprotective effects on heart failure by the mechanism of preserving the adult metabolic gene regulation.

  6. Mechanism of reversible self-association of a monoclonal antibody: role of electrostatic and hydrophobic interactions.

    Science.gov (United States)

    Esfandiary, Reza; Parupudi, Arun; Casas-Finet, Jose; Gadre, Dhanesh; Sathish, Hasige

    2015-02-01

    Reversible self-association of protein therapeutics, the phenomenon of formation of native reversible oligomeric species as a result of noncovalent intermolecular interactions, can add additional manufacturing, stability, delivery, and safety complexities in biopharmaceutical development. Its early detection, characterization, and mitigation can therefore contribute to the success of drug development. A variety of structural and environmental factors can contribute to the modulation of self-association with mechanisms still elusive in some cases due to the inherent structural complexity of proteins. By combining the capabilities of dynamic and static light scattering techniques, the modulatory effects of a variety of solution conditions on a model IgG1's (mAbA) intermolecular interactions have been utilized to derive mechanism of its self-association at relatively low-protein concentration. The analysis of the effect of pH, buffer type, Hofmeister salts, and aromatic amino acids utilizing light scattering supported a combined role of hydrophobic and electrostatic interactions in mAbA self-association. Fitting of the data into the equilibrium models obtained from the multiangle static light scattering provided the enthalpic and entropic contributions of self-association, highlighting the more dominant effect of electrostatic interactions. In addition, studies of the Fab and Fc fragments of mAbA suggested the key role of the former in observed self-association. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  7. Reverse task of passive and active mechanical system in torsional vibrations

    Directory of Open Access Journals (Sweden)

    K. Białas

    2009-08-01

    Full Text Available Purpose: The main aim of this paper is to develop a method for finding structure and parameters, i.e. a structural and parameter synthesis, of an active model of a viscous damper mechanical system in vibrations. The aim is to perfect the synthesis seen as modification at the sub-assembly design level in relation to the required spectrum of vibration frequency of the system.Design/methodology/approach: With complex systems classic design is very time consuming and it does not always produce satisfactory results. Therefore, it is necessary to use other design methods, such as the inverse task, which is called synthesis. It is searching for a system structure, together with elements value, which realizes the required frequency characteristics.Findings: Using the active elements allows complete elimination of the oscillations. The conducted analysis show that it is not necessary to use both the active and passive elements, as using only active elements produces the same results.Research limitations/implications: The scope of discussion is reverse task of mechanical system in torsional vibrations including passive and active elements, but for this type of systems, such approach is sufficient.Practical implications: The methods of reverse task and analysis can be base of design and construct for this type of mechanic systems.Originality/value: Thank to the approach, introduced in this paper, can be conducted as early as during the designing of future functions of the system as well as during the construction of the system. Using method and obtained results can be value for designers of mechanical systems with elements reducing vibrations.

  8. Mechanics and complications of reverse shoulder arthroplasty: morse taper failure analysis and prospective rectification

    Science.gov (United States)

    Hoskin, HLD; Furie, E.; Collins, W.; Ganey, TM; Schlatterer, DR

    2017-05-01

    Since Sir John Charnley began his monumental hip arthroplasty work in 1958, clinical researchers have been incrementally improving longevity and functionality of total joint systems, although implant failure occurs on occasion. The purpose of this study is to report the fracture of the humeral tray Morse taper of a reverse total shoulder system (RTSS), which to date has not been reported with metallurgic analysis for any RTSS. There was no reported antecedent fall, motor vehicle collision, or other traumatic event prior to implant fracture in this case. Analysis was performed on the retrieved failed implant by Scanning Electron Microscopy (SEM) and Electron Dispersion Spectroscopy (EDS) in an attempt to determine the failure method, as well as to offer improvements for future implants. At the time of revision surgery all explants were retained from the left shoulder of a 61-year old male who underwent a non-complicated RTSS 4 years prior. The explants, particularly the cracked humeral tray, were processed as required for SEM and EDS. Analysis was performed on the failure sites in order to determine the chemical composition of the different parts of the implant, discover the chemical composition of the filler metal used during the electron beam welding process, and to detect any foreign elements that could suggest corrosion or other evidence of failure etiology. Gross visual inspection of all explants revealed that implant failure was a result of dissociation of the taper from the humeral tray at the weld, leaving the Morse taper embedded in the humeral stem while the tray floated freely in the patient’s shoulder. SEM further confirmed the jagged edges noted grossly at the weld fracture site, both suggesting failure due to torsional forces. EDS detected elevated levels of carbon and oxygen at the fracture site on the taper only and not on the humeral tray. In order to determine the origin of the high levels of C and O, it was considered that in titanium alloys, C

  9. 46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates...

  10. Kinetic effects on double hysteresis in spin crossover molecular magnets analyzed with first order reversal curve diagram technique

    Energy Technology Data Exchange (ETDEWEB)

    Stan, Raluca-Maria; Gaina, Roxana; Enachescu, Cristian, E-mail: cristian.enachescu@uaic.ro, E-mail: radu.tanasa@uaic.ro; Stancu, Alexandru [Faculty of Physics, Alexandru Ioan Cuza University, 700506 Iasi (Romania); Tanasa, Radu, E-mail: cristian.enachescu@uaic.ro, E-mail: radu.tanasa@uaic.ro [Faculty of Physics, Alexandru Ioan Cuza University, 700506 Iasi (Romania); Department of Engineering, University of Cambridge, CB2 1PZ Cambridge (United Kingdom); Bronisz, Robert [Faculty of Chemistry, University of Wroclaw, 50-383 Wroclaw (Poland)

    2015-05-07

    In this paper, we analyze two types of hysteresis in spin crossover molecular magnets compounds in the framework of the First Order Reversal Curve (FORC) method. The switching between the two stable states in these compounds is accompanied by hysteresis phenomena if the intermolecular interactions are higher than a threshold. We have measured the static thermal hysteresis (TH) and the kinetic light induced thermal hysteresis (LITH) major loops and FORCs for the polycrystalline Fe(II) spin crossover compound [Fe{sub 1−x}Zn{sub x}(bbtr){sub 3}](ClO{sub 4}){sub 2} (bbtr = 1,4-di(1,2,3-triazol-1-yl)butane), either in a pure state (x = 0) or doped with Zn ions (x = 0.33) considering different sweeping rates. Here, we use this method not only to infer the domains distribution but also to disentangle between kinetic and static components of the LITH and to estimate the changes in the intermolecular interactions introduced by dopants. We also determined the qualitative relationship between FORC distributions measured for TH and LITH.

  11. Reversible and irreversible changes of surface morphology by order-disorder transition in CuAu alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sachl, Jindrich; Sima, Vladimir; Pfeiler, Wolfgang

    2004-09-22

    The change of symmetry from the disordered fcc structure to tetragonal or orthorhombic structure is accompanied in CuAu alloy by anisotropy of lattice parameters and also by local generation of c-variants of structural antiphase domains. Macroscopic results of these processes can be observed as a dynamic change of the surface morphology. Some surface changes are reversible, on the other hand the internal stresses connected with the order-disorder transformation are also responsible for irreversible surface deformation effects. The domain structure formation can be influenced by external load and a shape memory effect can be observed at special conditions in CuAu. A combination of in-situ microscopic video cinematography and post-mortem 3-D atomic force microscopy (AFM) has been used for the surface study. The AFM images have enabled a detailed analysis of the surface morphology and the cinematography has given an in-situ information dealing with conditions and kinetics of observed surface changes. Measurements on CuAu single- and poly-crystalline samples have been made for a wide variety of experimental conditions (heating/cooling rates, external load, thermal history of the sample)

  12. Low Power S-Box Architecture for AES Algorithm using Programmable Second Order Reversible Cellular Automata: An Application to WBAN.

    Science.gov (United States)

    Gangadari, Bhoopal Rao; Ahamed, Shaik Rafi

    2016-12-01

    In this paper, we presented a novel approach of low energy consumption architecture of S-Box used in Advanced Encryption Standard (AES) algorithm using programmable second order reversible cellular automata (RCA (2)). The architecture entails a low power implementation with minimal delay overhead and the performance of proposed RCA (2) based S-Box in terms of security is evaluated using the cryptographic properties such as nonlinearity, correlation immunity bias, strict avalanche criteria, entropy and also found that the proposed architecture is secure enough for cryptographic applications. Moreover, the proposed AES algorithm architecture simulation studies show that energy consumption of 68.726 nJ, power dissipation of 3.856 mW for 0.18- μm at 13.69 MHz and energy consumption of 29.408 nJ, power dissipation of 1.65 mW for 0.13- μm at 13.69 MHz. The proposed AES algorithm with RCA (2) based S-Box shows a reduction power consumption by 50 % and energy consumption by 5 % compared to best classical S-Box and composite field arithmetic based AES algorithm. Apart from that, it is also shown that RCA (2) based S-Boxes are dynamic in nature, invertible, low power dissipation compared to that of LUT based S-Box and hence suitable for Wireless Body Area Network (WBAN) applications.

  13. Higher order structural effects stabilizing the reverse watson-crick guanine-cytosine base pair in functional RNAs

    KAUST Repository

    Chawla, Mohit

    2013-10-10

    The G:C reverse Watson-Crick (W:W trans) base pair, also known as Levitt base pair in the context of tRNAs, is a structurally and functionally important base pair that contributes to tertiary interactions joining distant domains in functional RNA molecules and also participates in metabolite binding in riboswitches. We previously indicated that the isolated G:C W:W trans base pair is a rather unstable geometry, and that dicationic metal binding to the Guanine base or posttranscriptional modification of the Guanine can increase its stability. Herein, we extend our survey and report on other H-bonding interactions that can increase the stability of this base pair. To this aim, we performed a bioinformatics search of the PDB to locate all the occurencies of G:C trans base pairs. Interestingly, 66% of the G:C trans base pairs in the PDB are engaged in additional H-bonding interactions with other bases, the RNA backbone or structured water molecules. High level quantum mechanical calculations on a data set of representative crystal structures were performed to shed light on the structural stability and energetics of the various crystallographic motifs. This analysis was extended to the binding of the preQ1 metabolite to a preQ1-II riboswitch. 2013 The Author(s).

  14. Reverse electrowetting -- a new approach to high-power harvesting of mechanical energy

    Science.gov (United States)

    Krupenkin, Tom; Taylor, J. Ashley; Manakasettharn, Supone

    2012-02-01

    Over the last decade electrical batteries have emerged as a critical bottleneck in portable electronics development. High-power mechanical energy harvesting can potentially provide a valuable alternative to the use of batteries, but until now, its adoption has been hampered by the lack of an efficient mechanical-to-electrical energy conversion technology. In this talk a novel mechanical-to-electrical energy conversion method is discussed. The method is based on reverse electrowetting (REWOD) -- a novel microfluidic phenomenon. Electrical energy generation is achieved through the interaction of arrays of moving microscopic liquid droplets with novel nanometer-thick multilayer dielectric films. Advantages of this process include the production of high power densities, up to 1 KW sq. m; the ability to directly utilize a very broad range of mechanical forces and displacements; and the ability to directly output a broad range of currents and voltages, from several volts to tens of volts. We hope that the REWOD-based energy harvesting can provide a novel technology platform for a broad range of new electronic products and enable reduction of cost, pollution, and other problems associated with the wide-spread battery use.

  15. Selfish punishment with avoiding mechanism can alleviate both first-order and second-order social dilemma

    CERN Document Server

    Cui, Pengbi

    2014-01-01

    Punishment, especially selfish punishment, has recently been identified as a potent promoter in sustaining or even enhancing the cooperation among unrelated individuals. However, without other key mechanisms, the first-order social dilemma and second-order social dilemma are still two enduring conundrums in biology and the social sciences even with the presence of punishment. In the present study, we investigate a spatial evolutionary four-strategy prisoner's dilemma game model with avoiding mechanism, where the four strategies are cooperation, defection, altruistic and selfish punishment. By introducing the low level of random mutation of strategies, we demonstrate that the presence of selfish punishment with avoiding mechanism can alleviate the two kinds of social dilemmas for various parametrizations. In addition, we propose an extended pair approximation method, whose solutions can essentially estimate the dynamical behaviors and final evolutionary frequencies of the four strategies. At last, considering ...

  16. Order information coding in working memory: Review of behavioural studies and cognitive mechanisms

    Directory of Open Access Journals (Sweden)

    Barbara Dolenc

    2014-06-01

    Full Text Available Executive processes, such as coding for sequential order, are of extreme importance for higher-order cognitive tasks. One of the significant questions is, how order information is coded in working memory and what cognitive mechanisms and processes mediate it. The aim of this review paper is to summarize results of studies that explore whether order and item memory are two separable processes. Furthermore, we reviewed evidence for each of the proposed cognitive mechanism that might mediate order processing. Previous behavioural and neuroimaging data suggest different representation and processing of item and order information in working memory. Both information are maintained and recalled separately and this separation seems to hold for recognition as well as for recall. To explain the result of studies of order coding, numerous cognitive mechanisms were proposed. We focused on four different mechanisms by which order information might be coded and retrieved, namely inter-item associations, direct coding, hierarchical coding and magnitude coding. Each of the mechanisms can explain some of the aspect of order information coding, however none of them is able to explain all of the empirical findings. Due to its complex nature it is not surprising that a single mechanism has difficulties accounting for all the behavioral data and order memory may be more accurately characterized as the result of a set of mechanisms rather than a single one. Moreover, the findings beget a question of whether different types of memory for order information might exist.

  17. Reversible and rapid transfer-RNA deactivation as a mechanism of translational repression in stress.

    Science.gov (United States)

    Czech, Andreas; Wende, Sandra; Mörl, Mario; Pan, Tao; Ignatova, Zoya

    2013-08-01

    Stress-induced changes of gene expression are crucial for survival of eukaryotic cells. Regulation at the level of translation provides the necessary plasticity for immediate changes of cellular activities and protein levels. In this study, we demonstrate that exposure to oxidative stress results in a quick repression of translation by deactivation of the aminoacyl-ends of all transfer-RNA (tRNA). An oxidative-stress activated nuclease, angiogenin, cleaves first within the conserved single-stranded 3'-CCA termini of all tRNAs, thereby blocking their use in translation. This CCA deactivation is reversible and quickly repairable by the CCA-adding enzyme [ATP(CTP):tRNA nucleotidyltransferase]. Through this mechanism the eukaryotic cell dynamically represses and reactivates translation at low metabolic costs.

  18. Reversible and rapid transfer-RNA deactivation as a mechanism of translational repression in stress.

    Directory of Open Access Journals (Sweden)

    Andreas Czech

    2013-08-01

    Full Text Available Stress-induced changes of gene expression are crucial for survival of eukaryotic cells. Regulation at the level of translation provides the necessary plasticity for immediate changes of cellular activities and protein levels. In this study, we demonstrate that exposure to oxidative stress results in a quick repression of translation by deactivation of the aminoacyl-ends of all transfer-RNA (tRNA. An oxidative-stress activated nuclease, angiogenin, cleaves first within the conserved single-stranded 3'-CCA termini of all tRNAs, thereby blocking their use in translation. This CCA deactivation is reversible and quickly repairable by the CCA-adding enzyme [ATP(CTP:tRNA nucleotidyltransferase]. Through this mechanism the eukaryotic cell dynamically represses and reactivates translation at low metabolic costs.

  19. Reverse engineering the mechanical and molecular pathways in stem cell morphogenesis.

    Science.gov (United States)

    Lu, Kai; Gordon, Richard; Cao, Tong

    2015-03-01

    The formation of relevant biological structures poses a challenge for regenerative medicine. During embryogenesis, embryonic cells differentiate into somatic tissues and undergo morphogenesis to produce three-dimensional organs. Using stem cells, we can recapitulate this process and create biological constructs for therapeutic transplantation. However, imperfect imitation of nature sometimes results in in vitro artifacts that fail to recapitulate the function of native organs. It has been hypothesized that developing cells may self-organize into tissue-specific structures given a correct in vitro environment. This proposition is supported by the generation of neo-organoids from stem cells. We suggest that morphogenesis may be reverse engineered to uncover its interacting mechanical pathway and molecular circuitry. By harnessing the latent architecture of stem cells, novel tissue-engineering strategies may be conceptualized for generating self-organizing transplants.

  20. Chaos, control and synchronization of a fractional order rotational mechanical system with a centrifugal governor

    Energy Technology Data Exchange (ETDEWEB)

    Ge Zhengming [Department of Mechanical Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 300, Taiwan (China)]. E-mail: zmg@cc.nctu.edu.tw; Jhuang Weiren [Department of Mechanical Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 300, Taiwan (China)

    2007-07-15

    Chaos, its control and synchronization for a fractional order rotational mechanical system with a centrifugal governor are studied for both the autonomous and the nonautonomous cases. It is found that chaos exists in the fractional order systems with order less than and more than the number of states of the system. Controlling the chaotic motion of a fractional order system to its equilibrium point is obtained for both the autonomous and the nonautonomous cases. The rotational mechanical systems with the same fractional order and with the different fractional orders are synchronized by linear coupling for both the autonomous and the nonautonomous cases.

  1. First order reversal curve analysis on NdFeB nanocomposite ribbons subjected to Joule heating treatments

    Energy Technology Data Exchange (ETDEWEB)

    Pampillo, L.G. [INTECIN-Instituto de Tecnologias y ciencias de la Ingenieria ' Hilario Fernandez Long' (UBA-CONICET), Facultad de Ingenieria, Paseo Colon 850 (C1063ACV), C. A. B. A. (Argentina); Saccone, F.D., E-mail: fsaccone@fi.uba.ar [INTECIN-Instituto de Tecnologias y ciencias de la Ingenieria ' Hilario Fernandez Long' (UBA-CONICET), Facultad de Ingenieria, Paseo Colon 850 (C1063ACV), C. A. B. A. (Argentina); Knobel, M. [Instituto de Fisica Gleb Wataghin-Departamento de Fisica de Materia Condensada-Universidade Estadual de Campinas, Cidade Universitaria Zeferino Vaz, Barao Geraldo 13083-970, Campinas, Sao Paulo (Brazil); Sirkin, H.R.M. [INTECIN-Instituto de Tecnologias y ciencias de la Ingenieria ' Hilario Fernandez Long' (UBA-CONICET), Facultad de Ingenieria, Paseo Colon 850 (C1063ACV), C. A. B. A. (Argentina)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Nd-lean amorphous precursors subjected to Joule heating. Black-Right-Pointing-Pointer Exchange-spring magnets. Black-Right-Pointing-Pointer FORC diagrams of irreversible switching fields. Black-Right-Pointing-Pointer This last techniques helped us to verify the optimized treatments conditions. - Abstract: Amorphous precursors with composition Nd{sub 4.5}Fe{sub 72-x}Co{sub 3+x}Cr{sub 2}Al{sub 1}B{sub 17.5} (x = 0, 2, 7, 12) were thermally treated by the Joule heating technique with a linearly varying electrical current. The crystallization kinetics was followed by monitoring the resistance of the ribbons during the heating up to the final applied current. Crystallized nanostructured phases coexist with an amorphous matrix, as it was observed by means of Moessbauer Spectroscopy and X-ray diffraction. The irreversible magnetic response of the Joule heated ribbons was analyzed by the First Order Reversal Curves (FORC) diagram technique. For the optimal treatments, associated with the higher maximum energy products for each sample composition, it was found that the main interaction is of a strongly dipolar characteristic. Over annealed samples show a FORC diagram that gives into account of softening, due to grain growth, for those phases precipitated at the first crystallization stage. When it is measured at 20 K, the hardest magnetic sample (Fe = 72 at.%, Co = 3 at.%, I{sub final} = 0.5 A), exhibits a diagram with characteristics corresponding to dipolar interactions of soft phases. This fact is consistent with an enhancement of the exchange length due to the increase in the soft phase stiffness as it is expected at low temperatures.

  2. Actuation Mechanism of Two-step Reverse Transformation Behavior in TiNi Alloys Deformed at Parent Phase

    Institute of Scientific and Technical Information of China (English)

    HUAILi-min; CUILi-shan; ZHANGLai-bin; ZHENGYan-jun

    2004-01-01

    The actuation mechanism of TiNi shape memory alloy wires, which were deformed at parentphase followed by a cooling process under constant strain constraint, was investigated. The experimental resuhsshow that the two-step reverse martensitic transformation behavior occurs during the heating process, and the tem-perature range of reverse transformation was olwiously widened with the increasing of prestrain,The recovery strainvs temperature curves exhibits an actuation eharaeteristic of linear output recovery strain in a wide temperaturerange.

  3. Exactly soluble local bosonic cocycle models, statistical transmutation, and simplest time-reversal symmetric topological orders in 3+1 dimensions

    Science.gov (United States)

    Wen, Xiao-Gang

    2017-05-01

    We propose a generic construction of exactly soluble local bosonic models that realize various topological orders with gappable boundaries. In particular, we construct an exactly soluble bosonic model that realizes a (3+1)-dimensional [(3+1)D] Z2-gauge theory with emergent fermionic Kramers doublet. We show that the emergence of such a fermion will cause the nucleation of certain topological excitations in space-time without pin+ structure. The exactly soluble model also leads to a statistical transmutation in (3+1)D. In addition, we construct exactly soluble bosonic models that realize 2 types of time-reversal symmetry-enriched Z2 topological orders in 2+1 dimensions, and 20 types of simplest time-reversal symmetry-enriched topological (SET) orders which have only one nontrivial pointlike and stringlike topological excitation. Many physical properties of those topological states are calculated using the exactly soluble models. We find that some time-reversal SET orders have pointlike excitations that carry Kramers doublet, a fractionalized time-reversal symmetry. We also find that some Z2 SET orders have stringlike excitations that carry anomalous (nononsite) Z2 symmetry, which can be viewed as a fractionalization of Z2 symmetry on strings. Our construction is based on cochains and cocycles in algebraic topology, which is very versatile. In principle, it can also realize emergent topological field theory beyond the twisted gauge theory.

  4. Reversal mechanisms and interactions in magnetic systems: coercivity versus switching field and thermally assisted demagnetization

    Directory of Open Access Journals (Sweden)

    Cebollada, F.

    2005-06-01

    Full Text Available In this paper we present a comparative analysis of the magnetic interactions and reversal mechanisms of two different systems: NdFeB-type alloys with grain sizes in the single domain range and Fe-SiO2 nanocomposites with Fe concentrations above and below the percolation threshold. We evidence that the use of the coercivity as the main parameter to analyse them might be misleading due to the convolution of both reversible and irreversible magnetization variations. We show that the switching field and thermally assisted demagnetization allow a better understanding of these mechanisms since they involve just irreversible magnetization changes. Specifically, the experimental analysis of the coercivity adquisition process for the NdFeB-type system suggests that the magnetization reversal is nucleated at the spin misalignments present due to intergranular exchange interactions. On the other hand, the study of the magnetic viscosity and of the isothermal remanent magnetization (IRM and direct field demagnetization (DCD remanence curves indicates that the dipolar interactions are responsible for the propagation of the switching started at individual particles.

    En este artículo presentamos un análisis comparativo de la influencia de la microestructura a través de las interacciones magnéticas en los mecanismos de inversión de la magnetización en dos sistemas diferentes: aleaciones tipo NdFeB con tamaños de grano en el rango de monodominio y nanocompuestos de Fe-SiO2 con concentraciones de Fe tanto por encima como por debajo del umbral de percolación. Ponemos de manifiesto que el uso del campo coercitivo como parámetro de análisis puede llevar a equívocos debido a la coexistencia de variaciones reversibles e irreversibles de la magnetización. También mostramos que el campo de conmutación y la desimanación térmicamente asistida permiten una mejor comprensión de dichos mecanismos ya que reflejan exclusivamente cambios irreversibles de

  5. Tree Removal as a Mechanism to Reverse Ecohydrologic Thresholds in Pinyon- and Juniper-Encroached Shrublands

    Science.gov (United States)

    Williams, C. J.; Pierson, F. B.; Nouwakpo, S.; Weltz, M.

    2016-12-01

    Pinyon and juniper encroachment has altered vegetation structure, ecological condition, hydrologic function, and delivery of ecosystem goods and services on millions of hectares of sagebrush rangelands in the western US. Pinyon and juniper out-compete shrubs and herbaceous vegetation for water and nutrients and facilitate a decline in vigor and cover of understory plants. These cover declines educe a shift from biotic-controlled resource retention to abiotic-driven losses of critical soil resources over time (soil erosion feedback). Our research objective was to evaluate tree removal by mastication, burning, and cutting as a threshold-reversal mechanism for restoration of sagebrush steppe ecohydrologic resilience over a ten year period. We examined vegetation, soils, infiltration, runoff, and erosion from artificial rainfall and concentrated flow experiments across multiple scales in two late succession woodlands before and 1, 2, and 10 yr after tree removal to address two research questions: 1) Can tree removal decrease late-succession woodland ecohydrologic resilience by increasing vegetation and ground cover within the first 10 yr post-treatment?, and 2) Is the soil erosion feedback reversible in the later stages of woodland encroachment? Distributing shredded tree debris into bare areas improved infiltration and reduced soil erosion in the first few years following tree mastication. Cutting and placing downed trees in bare patches had no initial effect on runoff and erosion. Burning initially reduced infiltration and increased runoff and erosion at the sites, but favorable grass and forb cover recruitment 2 yr after burning reduced erosion from the mostly bare intercanopy between tree mounds. Our presentation of the overall study will chronicle these published pre-fire, 1 yr, and 2 yr responses and preliminary results from the 10th yr post-treatment to address the questions outlined above. The collective results advance understanding of pinyon and juniper

  6. Reversible, partial inactivation of plant betaine aldehyde dehydrogenase by betaine aldehyde: mechanism and possible physiological implications.

    Science.gov (United States)

    Zárate-Romero, Andrés; Murillo-Melo, Darío S; Mújica-Jiménez, Carlos; Montiel, Carmina; Muñoz-Clares, Rosario A

    2016-04-01

    In plants, the last step in the biosynthesis of the osmoprotectant glycine betaine (GB) is the NAD(+)-dependent oxidation of betaine aldehyde (BAL) catalysed by some aldehyde dehydrogenase (ALDH) 10 enzymes that exhibit betaine aldehyde dehydrogenase (BADH) activity. Given the irreversibility of the reaction, the short-term regulation of these enzymes is of great physiological relevance to avoid adverse decreases in the NAD(+):NADH ratio. In the present study, we report that the Spinacia oleracea BADH (SoBADH) is reversibly and partially inactivated by BAL in the absence of NAD(+)in a time- and concentration-dependent mode. Crystallographic evidence indicates that the non-essential Cys(450)(SoBADH numbering) forms a thiohemiacetal with BAL, totally blocking the productive binding of the aldehyde. It is of interest that, in contrast to Cys(450), the catalytic cysteine (Cys(291)) did not react with BAL in the absence of NAD(+) The trimethylammonium group of BAL binds in the same position in the inactivating or productive modes. Accordingly, BAL does not inactivate the C(450)SSoBADH mutant and the degree of inactivation of the A(441)I and A(441)C mutants corresponds to their very different abilities to bind the trimethylammonium group. Cys(450)and the neighbouring residues that participate in stabilizing the thiohemiacetal are strictly conserved in plant ALDH10 enzymes with proven or predicted BADH activity, suggesting that inactivation by BAL is their common feature. Under osmotic stress conditions, this novel partial and reversible covalent regulatory mechanism may contribute to preventing NAD(+)exhaustion, while still permitting the synthesis of high amounts of GB and avoiding the accumulation of the toxic BAL.

  7. New fundamental quantum mechanical operator-ordering identities for the coordinate and momentum operators

    Institute of Scientific and Technical Information of China (English)

    FAN HongYi

    2012-01-01

    In quantum mechanics theory one of the basic operator orderings is Q - P and P - Q ordering,where Q and P are the coordinate operator and the momentum operator,respectively.We derive some new fundamental operator identities about their mutual reordering.The technique of integration within Q - P ordering and P - Q ordering is introduced.The Q - P ordered and P - Q ordered formulas of the Wigner operator are also deduced which makes arranging the operators in either Q - P or P - Q ordering much more convenient.

  8. Temperature-dependent first-order reversal curve measurements on unusually hard magnetic low-temperature phase of MnBi

    Science.gov (United States)

    Muralidhar, Shreyas; Gräfe, Joachim; Chen, Yu-Chun; Etter, Martin; Gregori, Giuliano; Ener, Semih; Sawatzki, Simon; Hono, Kazuhiro; Gutfleisch, Oliver; Kronmüller, Helmut; Schütz, Gisela; Goering, Eberhard J.

    2017-01-01

    We have performed first-order reversal curve (FORC) measurements to investigate the irreversible magnetization processes in the low-temperature phase of MnBi. Using temperature-dependent FORC analysis, we are able to provide a clear insight into the effects of microstructural parameters such as grain diameter, shape, and surface composition on the coercivity of nucleation hardened permanent magnet MnBi. FORC diagrams of MnBi show a unique broadening and narrowing of the coercive field distribution with increasing temperature. We were able to microscopically identify the reason for this behavior, based on the shift in the single domain critical diameter from nearly 1 to 2 μ m , thereby changing the dependence of coercivity with particle size. This is based on a strong increase in the uniaxial anisotropy constant with increasing temperature. Furthermore, the results also give an additional confirmation that the magnetic hardening in low-temperature phase MnBi occurs due to nucleation mechanisms. In our case, we show that temperature-dependent FORC measurements provide a powerful tool for the microscopic understanding of high-performance permanent magnet systems.

  9. Facile Preparation and Formation Mechanism of Uniform Silver Nanoparticles Using OP-10 as Emulsifier in Reverse Microemulsion

    Institute of Scientific and Technical Information of China (English)

    WU Xia; WANG Ting; WU Hui

    2011-01-01

    Using the polymerizable hydrophobic styrene monomer as the dispersion medium and the traditional nonionic surfactant OP-10 as emulsifier, stable silver nanoparticles of narrow size distribution were prepared by a reverse (w/o) microemulsion method. The powder X-ray diffraction (XRD) pattern indicated that the obtained silver nanoparticles were of face-centered cubic structure.The results of the transmission electron microscopy (TEM) show that the final silver nanoparticles are of spherical structure with an average diameter of 15.2 nm and ofa Gaussian distribution. The internal high-ordered structure of silver nanoparticles was characterized by the field-emission high-resolution transmission electron microscopy (FEHRTEM), indicating that the silver is monocrystalline and it has only one nucleation site during the formation process of a nanoparticle. The time-resolved UV-visible absorption spectra was used to monitor the process of the reaction in situ. The results show that the concentration of silver nanoparticles increases but the size changes little and the morphology transforms from obvious ellipsoidal shape to nearly spherical shape during the process. The experimental results indicate that the droplets' dynamic exchange which is closely related to the nature of surfactant film is the control factor of the kinetics. The dynamic exchange mechanism of silver nanoparticle formation is proposed to involve continual encounter of two separate droplets forming transient fused dimer in which the chemical reaction occurs followed by re-separation without combination. Attributed to the dual role of surfactant in the nanoparticle formation, tailored nanoparticles can be successfully synthesized in control in the premise of a certain stability of reverse microemulsion.

  10. Selfish punishment with avoiding mechanism can alleviate both first-order and second-order social dilemma.

    Science.gov (United States)

    Cui, Pengbi; Wu, Zhi-Xi

    2014-11-21

    Punishment, especially selfish punishment, has recently been identified as a potent promoter in sustaining or even enhancing the cooperation among unrelated individuals. However, without other key mechanisms, the first-order social dilemma and second-order social dilemma are still two enduring conundrums in biology and the social sciences even with the presence of punishment. In the present study, we investigate a spatial evolutionary four-strategy prisoner׳s dilemma game model with avoiding mechanism, where the four strategies are cooperation, defection, altruistic and selfish punishment. By introducing the low level of random mutation of strategies, we demonstrate that the presence of selfish punishment with avoiding mechanism can alleviate the two kinds of social dilemmas for various parametrizations. In addition, we propose an extended pair approximation method, whose solutions can essentially estimate the dynamical behaviors and final evolutionary frequencies of the four strategies. At last, considering the analogy between our model and the classical Lotka-Volterra system, we introduce interaction webs based on the spatial replicator dynamics and the transformed payoff matrix to qualitatively characterize the emergent co-exist strategy phases, and its validity are supported by extensive simulations.

  11. Basic principles and aims of model order reduction in compliant mechanisms

    Directory of Open Access Journals (Sweden)

    M. Rösner

    2011-10-01

    Full Text Available Model order reduction appears to be beneficial for the synthesis and simulation of compliant mechanisms due to computational costs. Model order reduction is an established method in many technical fields for the approximation of large-scale linear time-invariant dynamical systems described by ordinary differential equations. Based on system theory, underlying representations of the dynamical system are introduced from which the general reduced order model is derived by projection. During the last years, numerous new procedures were published and investigated appropriate to simulation, optimization and control. Singular value decomposition, condensation-based and Krylov subspace methods representing three order reduction methods are reviewed and their advantages and disadvantages are outlined in this paper. The convenience of applying model order reduction in compliant mechanisms is quoted. Moreover, the requested attributes for order reduction as a future research direction meeting the characteristics of compliant mechanisms are commented.

  12. Kinetics and mechanism of the cutinase-catalyzed transesterification of oils in AOT reversed micellar system.

    Science.gov (United States)

    Badenes, Sara M; Lemos, Francisco; Cabral, Joaquim M S

    2011-11-01

    The kinetics of the enzymatic transesterification between a mixture of triglycerides (oils) and methanol for biodiesel production in a bis(2-ethylhexyl) sodium sulfosuccinate (AOT)/isooctane reversed micellar system, using recombinant cutinase from Fusarium solani pisi as a catalyst, was investigated. In order to describe the results that were obtained, a mechanistic scheme was proposed, based on the literature and on the experimental data. This scheme includes the following reaction steps: the formation of the active enzyme-substrate complex, the addition of an alcohol molecule to the complex followed by the separation of a molecule of the fatty acid alkyl ester and a glycerol moiety, and release of the active enzyme. Enzyme inhibition and deactivation effects due to methanol and glycerol were incorporated in the model. This kinetic model was fitted to the concentration profiles of the fatty acid methyl esters (the components of biodiesel), tri-, di- and monoglycerides, obtained for a 24 h transesterification reaction performed in a stirred batch reactor under different reaction conditions of enzyme and initial substrates concentration.

  13. Higher order structural effects stabilizing the reverse Watson-Crick Guanine-Cytosine base pair in functional RNAs

    National Research Council Canada - National Science Library

    Chawla, Mohit; Abdel-Azeim, Safwat; Oliva, Romina; Cavallo, Luigi

    2014-01-01

    The G:C reverse Watson-Crick (W:W trans) base pair, also known as Levitt base pair in the context of tRNAs, is a structurally and functionally important base pair that contributes to tertiary interactions joining distant domains...

  14. Retention mechanism for polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography with monomeric stationary phases.

    Science.gov (United States)

    Rafferty, Jake L; Siepmann, J Ilja; Schure, Mark R

    2011-12-23

    Reversed-phase liquid chromatography (RPLC) is the foremost technique for the separation of analytes that have very similar chemical functionalities, but differ only in their molecular shape. This ability is crucial in the analysis of various mixtures with environmental and biological importance including polycyclic aromatic hydrocarbons (PAHs) and steroids. A large amount of effort has been devoted to studying this phenomenon experimentally, but a detailed molecular-level description remains lacking. To provide some insight on the mechanism of shape selectivity in RPLC, particle-based simulations were carried out for stationary phases and chromatographic parameters that closely mimic those in an experimental study by Sentell and Dorsey [J. Chromatogr. 461 (1989) 193]. The retention of aromatic hydrocarbons ranging in size from benzene to the isomeric PAHs of the formula C(18)H(12) was examined for model RPLC systems consisting of monomeric dimethyl octadecylsilane (ODS) stationary phases with surface coverages ranging from 1.6 to 4.2 μmol/m(2) (i.e., stationary phases yielding low to intermediate shape selectivity) in contact with a 67/33 mol% acetonitrile/water mobile phase. The simulations show that the stationary phase acts as a very heterogeneous environment where analytes with different shapes prefer different spatial regions with specific local bonding environments of the ODS chains. However, these favorable retentive regions cannot be described as pre-existing cavities because the chain conformation in these local stationary phase regions adapts to accommodate the analytes.

  15. Mechanism of formation of metal sulfide ultrafine particles in reverse micelles using a gas injection method

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Hiroshi; Tsubaki, Yoritaka; Hirai, Takayuki; Komasawa, Isao [Osaka Univ., Toyonaka, Osaka (Japan)

    1997-01-01

    The mechanism of formation of ultrafine CdS, ZnS, and their composite particles by the injection of H{sub 2}S into reverse micelles was studied. The particle formation process was followed by the change in UV-visible absorption spectra. The kinetics of the whole process including dissolution of H{sub 2}S, nucleation, particle growth, and coagulation was analyzed from time-course changes of the size and number of formed particles. The dissolution of H{sub 2}S was the principal rate-determining step, and most of the dissolved H{sub 2}S was consumed for particle growth. The particles formed in the present gas injection method were larger in size than those in the previous solution-mixing method in most cases. A kinetic scheme based on the distribution of the species among the micelles was then proposed, and this successfully explained the particle growth. Composite particles of CdS and ZnS having mixed crystal or core-shell structures were also prepared, and the application of these particles as photocatalysts for the cleavage of water to generate H{sub 2} was then investigated.

  16. Reversible adaptive plasticity: A mechanism for neuroblastoma cell heterogeneity and chemo-resistance

    Directory of Open Access Journals (Sweden)

    Lina eChakrabarti

    2012-08-01

    Full Text Available We describe a novel form of tumor cell plasticity characterized by reversible adaptive plasticity in murine and human neuroblastoma. Two cellular phenotypes were defined by their ability to exhibit adhered, anchorage dependent (AD or sphere forming, anchorage independent (AI growth. The tumor cells could transition back and forth between the two phenotypes and the transition was dependent on the culture conditions. Both cell phenotypes exhibited stem-like features such as expression of nestin, self-renewal capacity and mesenchymal differentiation potential. The AI tumorspheres were found to be more resistant to chemotherapy and proliferated slower in vitro compared to the AD cells. Identification of specific molecular markers like MAP2, β-catenin and PDGFRβ enabled us to characterize and observe both phenotypes in established mouse tumors. Irrespective of the phenotype originally implanted in mice, tumors grown in vivo show phenotypic heterogeneity in molecular marker signatures and are indistinguishable in growth or histologic appearance. Similar molecular marker heterogeneity was demonstrated in primary human tumor specimens. Chemotherapy or growth factor receptor inhibition slowed tumor growth in mice and promoted initial loss of AD or AI heterogeneity, respectively. Simultaneous targeting of both phenotypes led to further tumor growth delay with emergence of new unique phenotypes. Our results demonstrate that neuroblastoma cells are plastic, dynamic and may optimize their ability to survive by changing their phenotype. Phenotypic switching appears to be an adaptive mechanism to unfavorable selection pressure and could explain the phenotypic and functional heterogeneity of neuroblastoma.

  17. On the ambiguity of the reaction rate constants in multivariate curve resolution for reversible first-order reaction systems.

    Science.gov (United States)

    Schröder, Henning; Sawall, Mathias; Kubis, Christoph; Selent, Detlef; Hess, Dieter; Franke, Robert; Börner, Armin; Neymeyr, Klaus

    2016-07-13

    If for a chemical reaction with a known reaction mechanism the concentration profiles are accessible only for certain species, e.g. only for the main product, then often the reaction rate constants cannot uniquely be determined from the concentration data. This is a well-known fact which includes the so-called slow-fast ambiguity. This work combines the question of unique or non-unique reaction rate constants with factor analytic methods of chemometrics. The idea is to reduce the rotational ambiguity of pure component factorizations by considering only those concentration factors which are possible solutions of the kinetic equations for a properly adapted set of reaction rate constants. The resulting set of reaction rate constants corresponds to those solutions of the rate equations which appear as feasible factors in a pure component factorization. The new analysis of the ambiguity of reaction rate constants extends recent research activities on the Area of Feasible Solutions (AFS). The consistency with a given chemical reaction scheme is shown to be a valuable tool in order to reduce the AFS. The new methods are applied to model and experimental data.

  18. Nano/ultrafine grained austenitic stainless steel through the formation and reversion of deformation-induced martensite: Mechanisms, microstructures, mechanical properties, and TRIP effect

    Energy Technology Data Exchange (ETDEWEB)

    Shirdel, M., E-mail: mshirdel1989@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Mirzadeh, H., E-mail: hmirzadeh@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Advanced Metalforming and Thermomechanical Processing Laboratory, School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Parsa, M.H., E-mail: mhparsa@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Center of Excellence for High Performance Materials, School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Advanced Metalforming and Thermomechanical Processing Laboratory, School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2015-05-15

    A comprehensive study was carried out on the strain-induced martensitic transformation, its reversion to austenite, the resultant grain refinement, and the enhancement of strength and strain-hardening ability through the transformation-induced plasticity (TRIP) effect in a commercial austenitic 304L stainless steel with emphasis on the mechanisms and the microstructural evolution. A straightforward magnetic measurement device, which is based on the measurement of the saturation magnetization, for evaluating the amount of strain-induced martensite after cold rolling and reversion annealing in metastable austenitic stainless steels was used, which its results were in good consistency with those of the X-ray diffraction (XRD) method. A new parameter called the effective reduction in thickness was introduced, which corresponds to the reasonable upper bound on the obtainable martensite fraction based on the saturation in the martensitic transformation. By means of thermodynamics calculations, the reversion mechanisms were estimated and subsequently validated by experimental results. The signs of thermal martensitic transformation at cooling stage after reversion at 850 °C were found, which was attributed to the rise in the martensite start temperature due to the carbide precipitation. After the reversion treatment, the average grain sizes were around 500 nm and the nanometric grains of the size of ~ 65 nm were also detected. The intense grain refinement led to the enhanced mechanical properties and observation of the change in the work-hardening capacity and TRIP effect behavior. A practical map as a guidance for grain refining and characterizing the stability against grain growth was proposed, which shows the limitation of the reversion mechanism for refinement of grain size. - Graphical abstract: Display Omitted - Highlights: • Nano/ultrafine grained austenitic stainless steel through martensite treatment • A parameter descriptive of a reasonable upper bound on

  19. A fourth order accuracy summation-by-parts finite difference scheme for acoustic reverse time migration in boundary-conforming grids

    Science.gov (United States)

    Wang, Ying; Zhou, Hui; Yuan, Sanyi; Ye, Yameng

    2017-01-01

    The fourth order accuracy finite difference scheme is known advantageous in reducing memory and improving efficiency. Summation-by-parts finite difference operator is a natural way for wavefield simulation in complicated domains containing surface topography and irregular interfaces. The application of summation-by-parts method guarantees the stability of numerical approximation for heterogeneous media on curvilinear grids. This paper extends the second order summation-by-parts finite difference method to the fourth order case for the discretization of acoustic wave equation and perfect matched layer in boundary-conforming grids. In particular, the implementation of the fourth order method for wavefield simulation and reverse time migration in complicated domains can significantly improve the efficiency and decrease the storage. The elliptic method is applied for boundary-conforming grid generation in complicated domains. Under such grids, the two-dimensional acoustic wave equation in second order displacement formulation is compactly reformulated for forward modeling and reverse time migration, and the symmetric and compact form of perfectly matched layers expressed in a curvilinear coordinate system are applied to suppress artificial reflections. The discretizations of the acoustic wave equation and perfectly matched layer formula are fourth and second order accuracy in space and time respectively, where the spatial discretization satisfies the principle of summation-by-parts and is stable. Numerical experiments are presented to compare the accuracy of the second with fourth order summation-by-parts finite difference methods and to evaluate the efficiency of reverse time migration by using these two methods. As well, comparisons are performed between the fourth order accuracy summation-by-parts finite difference method and central finite difference method to illustrate the stability superiority of summation-by-parts operators.

  20. Mechanical continuity and reversible chromosome disassembly within intact genomes removed from living cells

    Science.gov (United States)

    Maniotis, A. J.; Bojanowski, K.; Ingber, D. E.

    1997-01-01

    decondensation which could be reversed by addition of histone H1, but not histones H2b or H3. These data suggest that DNA, its associated protein scaffolds, and surrounding cytoskeletal networks function as a structurally-unified system. Mechanical coupling within the nucleoplasm may coordinate dynamic alterations in chromatin structure, guide chromosome movement, and ensure fidelity of mitosis.

  1. Watermarking Capable of Identifying Embedding Order Based on an Arithmetic Mechanism

    Institute of Scientific and Technical Information of China (English)

    张新鹏; 王朔中; 张开文

    2003-01-01

    A digital watermark as a means for copyright protection may be crippled when a fake mark is embedded on top of it since both watermarks are detectable. In dealing with this problem, a watermarking scheme that does not satisfy the law of commutation is proposed. In this scheme, an order function based on an arithmetic mechanism is employed to identify the embedding order without affecting detection of the regular watermark. An earlier watermark corresponds to a larger value of the order function. In this way, the embedding order or watermarks can be identified according to the order function.

  2. 46 CFR 113.35-9 - Mechanical engine order telegraph systems.

    Science.gov (United States)

    2010-10-01

    ... indicators mechanically connected to each other, as by means of chains and wires. (b) Each transmitter and each indicator must have an audible signal device to indicate, in the case of an indicator, the receipt of an order, and in the case of a transmitter, the acknowledgment of an order. The audible signal...

  3. Mechanism of Ascorbic Acid-induced Reversion Against Malignant Phenotype in Human Gastric Cancer Cells

    Institute of Scientific and Technical Information of China (English)

    YA-XUAN SUN; QIU-SHENG ZHENG; GANG LI; DE-AN GUO; ZI-REN WANG

    2006-01-01

    Objective To find out the mechanisms of redifferentiation and reversion of malignant human gastric cancer cells induced by ascorbic acid. Methods Human gastric cancer cells grown in the laboratory were used. The Trypan blue dye exclusion method was used to determine the cell doubling time. The electrophoresis rate and colonogenic potential were the indices used to measure the rate of redifferentiation. The content of malondialdehyde (MDA) was measured using the thiobarbituric acid(TBA) method. The activities of superoxide dismutase (SOD), catalase (CAT) and the content of H2O2 were evaluated by spectrophotography. Results Six mmol/L ascorbic acid was used as a positive control. Human gastric cancer cells were treated with 75 μm hydrogen peroxide, which alleviated many of the malignant characteristics. For example, the cell surface charge obviously decreased and the electrophoresis rate dropped from 2.21 to 1.10 μm·s-1·V-1·cm-1. The colonogenic potential, a measure of cell differentiation, decreased 90.2%. After treatment with ascorbic acid, there was a concentration- and time-dependent increase in hydrogen peroxide (H2O2) and the activity of superoxide dismutase (SOD). However, the activity of catalase (CAT) resulted in a concentration- and time-dependent decrease. SOD and 3-amino-1,2,4-triazole (AT) exhibited some effects, but there were statistically significant differences between the SOD and AT group and the H2O2 group. Conclusions Ascorbic acid induces growth inhibition and redifferentiation of human gastric cancer cells through the production of hydrogen peroxide.

  4. Dehydrogenation kinetics, reversibility, and reaction mechanisms of reversible hydrogen storage material based on nanoconfined MgH2-NaAlH4

    Science.gov (United States)

    Plerdsranoy, Praphatsorn; Meethom, Sukanya; Utke, Rapee

    2015-12-01

    Studies of dehydrogenation kinetics, reversibility, and reaction mechanisms during de/rehydrogenation of nanoconfined MgH2-NaAlH4 into carbon aerogel scaffold (CAS) for reversible hydrogen storage material are for the first time proposed. Two different MgH2:NaAlH4 molar ratios (1:1 and 2:1) of hydride composite are melt infiltrated into CAS under 1:1 (CAS:hydride composite) weight ratio. Successful nanoconfinement is confirmed by N2 adsorption-desorption. Multiple-step dehydrogenation of milled samples is reduced to two-step reaction due to nanoconfinement. Peak temperatures corresponding to main dehydrogenation of nanoconfined samples significantly reduce as compared with those of milled samples, i.e., ∆T=up to 50 and 34 °C for nanoconfined sample with 1:1 and 2:1 (MgH2:NaAlH4) molar ratios, respectively. Hydrogen content released (the 1st cycle) and reproduced (the 2nd, 3rd, and 4th cycles) of nanoconfined samples enhance up to 80% and 68% with respect to theoretical hydrogen storage capacity, respectively, while those of milled samples are 71% and 38%, respectively. Remarkable hydrogen content reproduced after nanoconfinement is due to the fact that metallic Al obtained after dehydrogenation (T=300 °C under vacuum) of nanoconfined samples prefer to react with MgH2 and produces Al12Mg17, favorable for reversibility of MgH2-NaAlH4 system, whereas that of milled samples stays in the form of unreacted Al under the same temperature and pressure condition.

  5. Experimental and micromagnetic first-order reversal curves analysis in NdFeB-based bulk 'exchange spring'-type permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Chiriac, Horia [National Institute of Research and Development for Technical Physics, 47 Mangeron Boulevard, 700050, Iasi (Romania); Lupu, Nicoleta [National Institute of Research and Development for Technical Physics, 47 Mangeron Boulevard, 700050, Iasi (Romania); Stoleriu, Laurentiu [Al. I. Cuza University, Department of Solid State and Theoretical Physics, Blvd. Carol I, 11, 700506, Iasi (Romania)]. E-mail: lstoler@uaic.ro; Postolache, Petronel [Al. I. Cuza University, Department of Solid State and Theoretical Physics, Blvd. Carol I, 11, 700506, Iasi (Romania); Stancu, Alexandru [Al. I. Cuza University, Department of Solid State and Theoretical Physics, Blvd. Carol I, 11, 700506, Iasi (Romania)

    2007-09-15

    In this paper we present the results of applying the first-order reversal curves (FORC) diagram experimental method to the analysis of the magnetization processes of NdFeB-based permanents magnets. The FORC diagrams for this kind of exchange spring magnets show the existence of two magnetic phases-a soft magnetic phase and a hard magnetic one. Micromagnetic modeling is used for validating the hypotheses regarding the origin of the different features of the experimental FORC diagrams.

  6. Geomagnetic reversal rates following Palaeozoic superchrons have a fast restart mechanism.

    Science.gov (United States)

    Hounslow, Mark W

    2016-08-30

    Long intervals of single geomagnetic polarity (superchrons) reflect geodynamo processes, driven by core-mantle boundary interactions; however, it is not clear what initiates the start and end of superchrons, other than superchrons probably reflect lower heat flow across the core-mantle boundary compared with adjacent intervals. Here geomagnetic polarity timescales, with confidence intervals, are constructed before and following the reverse polarity Kiaman (Carboniferous-Permian) and Moyero (Ordovician) superchrons, providing a window into the geodynamo processes. Similar to the Cretaceous, asymmetry in reversal rates is seen in the Palaeozoic superchrons, but the higher reversal rates imply higher heatflow thresholds for entering the superchron state. Similar to the Cretaceous superchron, unusually long-duration chrons characterize the ∼10 Myr interval adjacent to the superchrons, indicating a transitional reversing state to the superchrons. This may relate to a weak pattern in the clustering of chron durations superimposed on the dominant random arrangement of chron durations.

  7. A computational model that predicts reverse growth in response to mechanical unloading.

    Science.gov (United States)

    Lee, L C; Genet, M; Acevedo-Bolton, G; Ordovas, K; Guccione, J M; Kuhl, E

    2015-04-01

    Ventricular growth is widely considered to be an important feature in the adverse progression of heart diseases, whereas reverse ventricular growth (or reverse remodeling) is often considered to be a favorable response to clinical intervention. In recent years, a number of theoretical models have been proposed to model the process of ventricular growth while little has been done to model its reverse. Based on the framework of volumetric strain-driven finite growth with a homeostatic equilibrium range for the elastic myofiber stretch, we propose here a reversible growth model capable of describing both ventricular growth and its reversal. We used this model to construct a semi-analytical solution based on an idealized cylindrical tube model, as well as numerical solutions based on a truncated ellipsoidal model and a human left ventricular model that was reconstructed from magnetic resonance images. We show that our model is able to predict key features in the end-diastolic pressure-volume relationship that were observed experimentally and clinically during ventricular growth and reverse growth. We also show that the residual stress fields generated as a result of differential growth in the cylindrical tube model are similar to those in other nonidentical models utilizing the same geometry.

  8. Investigation on mechanism of magnetization reversal for nanocrystalline Pr-Fe-B permanent magnets by micromagnetic finite element methods

    Institute of Scientific and Technical Information of China (English)

    ZHENG Bo; ZHAO Sufen

    2009-01-01

    Magnetization configurations were calculated under various magnetic fields for nanocrystalline Pr-Fe-B permanent magnets by micromagnetic finite element method. According to the configurations during demagnetization process, the mechanism of magnetization reversal was analyzed. For the Pr2Fe14B with 10 nm grains or its composite with 10vol.% α-Fe, the coercivity was determined by nucleation of reversed domain that took place at grain boundaries. However, for Pr2Fe14B with 30 nm grains, coercivity was controlled by pinning of the nucleated domain. For Pr2Fe14B/α-Fe with 30vol.% α-Fe, the demagnetization behavior was characterized by continuous reversal of α-Fe moment.

  9. Third-order nonlinear optical properties of spin-coating films containing benzo[α]phenoxazinium: from reverse saturated to saturated absorptions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fei [College of Chemistry, Chemical Engineering and Material Science, Soochow University, 199 Ren' Ai Road, Suzhou 215123 (China); Fang, Yu [School of Physical Science and Technology, Soochow University, 1 Shizi Street, Suzhou 215006 (China); Sun, Ru; Guo, Xiao-Zhi [College of Chemistry, Chemical Engineering and Material Science, Soochow University, 199 Ren' Ai Road, Suzhou 215123 (China); Song, Ying-Lin [School of Physical Science and Technology, Soochow University, 1 Shizi Street, Suzhou 215006 (China); Ge, Jian-Feng, E-mail: ge_jianfeng@hotmail.com [College of Chemistry, Chemical Engineering and Material Science, Soochow University, 199 Ren' Ai Road, Suzhou 215123 (China); Jiangsu Key Laboratory of Medical Optics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163 (China)

    2015-08-31

    The optical films based on poly(4-vinylphenol) and benzo[α]phenoxazinium dye with a long alkyl chain were obtained by spin-coating, and their optical properties are reported in this paper. UV–vis absorptions of the optical films showed that the absorption maxima were shifted about 40 nm by the influence of dye aggregation with increasing dye ratio. The third-order nonlinear optical properties of films were tested by Z-scan technique with a picosecond laser beam at 532 nm. The third-order nonlinear optical susceptibilities and second hyperpolarizabilities were up to 10{sup −10} and 10{sup −32} esu respectively. Meanwhile, the third-order nonlinear absorptions transformed from reverse saturated absorptions to saturated absorptions with increasing ratios of dye in doped films. The result of aggregation induced adjustable third-order nonlinear absorption can be confirmed from their TEM images. - Highlights: • Benzo[α]phenoxazinium containing optical films with poly(4-vinylphenol). • Optical property was influenced by dye aggregation. • The third-order nonlinear absorptions transformed from reverse saturated absorptions to saturated absorptions with increasing ratios of dye.

  10. Post-emplacement melt-flow as a feasible mechanism for reversed differentiation in tholeiitic sills

    Science.gov (United States)

    Aarnes, I.; Podladchikov, Y. Y.; Neumann, E.-R.; Galerne, C.

    2009-04-01

    This study provides a new explanation model for differentiation in sills, using a combination of geochemical data and field observations, numerical modeling and dimensional analysis. Geochemical data from a saucer-shaped dolerite sill intruded into the Karoo basin, South Africa reveal a process which causes reversed differentiation. The differentiation process is identified by D-shaped geochemical profiles. The notation is based on the vertical expression of whole-rock Mg-number (Mg# = 100*Mg/(Mg+Fetotal)) with the most primitive composition (i.e. high Mg#) in its center, and progressively more evolved composition (i.e. low Mg#) towards the upper and lower margins. Normal differentiation by fractional crystallization is known to produce C-shaped profiles (in terms of Mg# variations), as for example in the Skaergaard Intrusion. From a detailed field study of a saucer-shaped sill complex in the Karoo Basin, South Africa, we observe several different shapes (e.g. S, D and I) occurring within one sill. However, the C-shape is practically absent and hence fractional crystallization with double layer diffusion cannot be the main mechanism for differentiation in sheet intrusions. Several models have been proposed for the formation of D-shaped profiles, such as crystal settling and convection, multiple injections, flow differentiation, compositional convection, or Soret fractionation in combination with in situ crystallization. There is however no general agreement of one particular model, as they pose difficulties explaining all occurrences of D-shaped profiles. Based on numerical modeling we introduce post-emplacement flow as a feasible mechanism to explain the D-shaped profiles. A melt-flow can cause magmatic differentiation in the sill by transporting incompatible and less compatible elements associated with the melt phase (e.g. Zr and Fe) in an advective process through a stationary crystal network. Crystal networks of considerable strength are known to form in the

  11. Characteristic mechanical properties and complex ordered structures in metal films on liquid substrates

    Institute of Scientific and Technical Information of China (English)

    YU Senjiang; ZHANG Yongju; WU Liangneng; CUI Yujian; GE Hongliang

    2006-01-01

    Several metal (such as aluminum, iron etc.) film systems deposited on liquid (silicone oil) substrates have been successfully fabricated by a thermal evaporation method, and the special mechanical properties and complex ordered surface structures have been systematically studied. The experimental results show that there exists a compressive stress gradient in these films, making cracks nucleate at the film edges and then extend to the central regions gradually. Because the interaction between solid films and liquid substrates in the tangent direction is very small, the metal films can motion freely on the oil surfaces as a whole. In order to release the compressive stress, the broken film pieces collide, crush and superpose each other, which finally results in the formation of ordered band- shaped structures with an anti-symmetric characteristic. Based on the special mechanical properties of these nearly free sustained films, the morphologies and growth behaviors of the ordered structures are analyzed and discussed in detail.

  12. Mirror reversal and visual rotation are learned and consolidated via separate mechanisms: recalibrating or learning de novo?

    Science.gov (United States)

    Telgen, Sebastian; Parvin, Darius; Diedrichsen, Jörn

    2014-10-01

    Motor learning tasks are often classified into adaptation tasks, which involve the recalibration of an existing control policy (the mapping that determines both feedforward and feedback commands), and skill-learning tasks, requiring the acquisition of new control policies. We show here that this distinction also applies to two different visuomotor transformations during reaching in humans: Mirror-reversal (left-right reversal over a mid-sagittal axis) of visual feedback versus rotation of visual feedback around the movement origin. During mirror-reversal learning, correct movement initiation (feedforward commands) and online corrections (feedback responses) were only generated at longer latencies. The earliest responses were directed into a nonmirrored direction, even after two training sessions. In contrast, for visual rotation learning, no dependency of directional error on reaction time emerged, and fast feedback responses to visual displacements of the cursor were immediately adapted. These results suggest that the motor system acquires a new control policy for mirror reversal, which initially requires extra processing time, while it recalibrates an existing control policy for visual rotations, exploiting established fast computational processes. Importantly, memory for visual rotation decayed between sessions, whereas memory for mirror reversals showed offline gains, leading to better performance at the beginning of the second session than in the end of the first. With shifts in time-accuracy tradeoff and offline gains, mirror-reversal learning shares common features with other skill-learning tasks. We suggest that different neuronal mechanisms underlie the recalibration of an existing versus acquisition of a new control policy and that offline gains between sessions are a characteristic of latter.

  13. Exact solutions of the Fokker-Planck equation from an nth order supersymmetric quantum mechanics approach

    Energy Technology Data Exchange (ETDEWEB)

    Schulze-Halberg, Axel [Escuela Superior de Fisica y Matematicas, IPN, Unidad Profesional Adolfo Lopez Mateos, Col. San Pedro Zacatenco, Edificio 9, 07738 Mexico D.F. (Mexico)], E-mail: xbataxel@gmail.com; Rivas, Jesus Morales [Universidad Autonoma Metropolitana - Azcapotzalco, CBI - Area de Fisica Atomica Molecular Aplicada, Av. San Pablo 180, Reynosa Azcapotzalco, 02200 Mexico D.F. (Mexico)], E-mail: jmr@correo.azc.uam.mx; Pena Gil, Jose Juan [Universidad Autonoma Metropolitana - Azcapotzalco, CBI - Area de Fisica Atomica Molecular Aplicada, Av. San Pablo 180, Reynosa Azcapotzalco, 02200 Mexico D.F. (Mexico)], E-mail: jjpg@correo.azc.uam.mx; Garcia-Ravelo, Jesus [Escuela Superior de Fisica y Matematicas, IPN, Unidad Profesional Adolfo Lopez Mateos, Col. San Pedro Zacatenco, Edificio 9, 07738 Mexico D.F. (Mexico)], E-mail: ravelo@esfm.ipn.mx; Roy, Pinaki [Physics and Applied Mathematics Unit, Indian Statistical Institute, Calcutta-700108 (India)], E-mail: pinaki@isical.ac.in

    2009-04-20

    We generalize the formalism of nth order Supersymmetric Quantum Mechanics (n-SUSY) to the Fokker-Planck equation for constant diffusion coefficient and stationary drift potential. The SUSY partner drift potentials and the corresponding solutions of the Fokker-Planck equation are given explicitly. As an application, we generate new solutions of the Fokker-Planck equation by means of our first- and second-order transformation.

  14. Neutron total scattering and reverse Monte Carlo study of cation ordering in Ca(x)Sr(1-x)TiO(3).

    Science.gov (United States)

    Hui, Qun; Dove, Martin T; Tucker, Matthew G; Redfern, Simon A T; Keen, David A

    2007-08-22

    We use neutron total scattering measurements with reverse Monte Carlo analysis methods incorporating an atom-swapping algorithm to identify the short-range Ca/Sr cation ordering within the Ca(x)Sr(1-x)TiO(3) solid solution (compositions x = 0.2,0.5,0.8). Our results show that nearest-neighbour pairs have a strong tendency for unlike Ca/Sr first-neighbour coordination in the x = 0.2 and 0.5 cases. In the x = 0.5 case the Ca/Sr ordering results in a structure with space group P 2(1)nm. In contrast, there is much less short-range cation ordering in the x = 0.8 case.

  15. Optimal Control and higher-order mechanics for systems with symmetries

    CERN Document Server

    Colombo, Leonardo; de Diego, David Martin

    2012-01-01

    In this paper we will develop and design numerical methods for optimal control problems for a class of underactuated Lagrangian mechanical systems where the configuration manifold is a trivial principal bundle . We will construct these geometric integrators using discrete variational calculus, deriving a discrete version of the higher-order Euler-Lagrange equations on trivial principal bundles. The analysis applies to systems subject to higher-order constraints (that is, depending of higher-order derivatives as, for example, the acceleration). Interesting applications as, for instance, a discrete derivation of the Euler-Lagrange equations for higher-order Lagrangians and higher-order reduced Lagrangians, respectively, are shown. We find interesting applications both in the optimal control of an underactuated vehicle and the well-known plate ball problem seen as an optimization problem with nonholonomic constraints .

  16. Controlling fractional order chaotic systems based on Takagi-Sugeno fuzzy model and adaptive adjustment mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Yongai, E-mail: zhengyongai@163.co [Department of Computer, Yangzhou University, Yangzhou, 225009 (China); Nian Yibei [School of Energy and Power Engineering, Yangzhou University, Yangzhou, 225009 (China); Wang Dejin [Department of Computer, Yangzhou University, Yangzhou, 225009 (China)

    2010-12-01

    In this Letter, a kind of novel model, called the generalized Takagi-Sugeno (T-S) fuzzy model, is first developed by extending the conventional T-S fuzzy model. Then, a simple but efficient method to control fractional order chaotic systems is proposed using the generalized T-S fuzzy model and adaptive adjustment mechanism (AAM). Sufficient conditions are derived to guarantee chaos control from the stability criterion of linear fractional order systems. The proposed approach offers a systematic design procedure for stabilizing a large class of fractional order chaotic systems from the literature about chaos research. The effectiveness of the approach is tested on fractional order Roessler system and fractional order Lorenz system.

  17. Edge-based lightweight image encryption using chaos-based reversible hidden transform and multiple-order discrete fractional cosine transform

    Science.gov (United States)

    Zhang, Yushu; Xiao, Di; Wen, Wenying; Tian, Yuan

    2013-12-01

    In some special multimedia applications, only the regions with semantic information should be provided better protection whereas the other smooth regions can be free of encryption. However, most of the existing multimedia security schemes only consider bits and pixels rather than semantic information during their encryption. Motivated by this, we propose an edge-based lightweight image encryption scheme using chaos-based reversible hidden transform and multiple-order discrete fractional cosine transform. An image is first carried out by the edge detection based on advanced CNN structure with adaptive thresholds to assess data significance in the image. The detection output is a binary image, in which a “1” reflects the detected pixel whereas a “0” is opposite. Both the detected image and the original image are divided into non-overlapping pixel blocks in the same way, respectively. Whether each block is encrypted or not depends on the significance judged by the corresponding detected block. The significant block is performed by reversible hidden transform followed by multiple-order discrete fractional cosine transform parameters and orders of these two transforms are determined by a two dimensional cross chaotic map. Experiment results show the significant contour features of an image that have been largely hidden only by encrypting about half pixels in the average sense. The keys are extremely sensitive and the proposed scheme can resist noise attack to some extent.

  18. Analysis of Reverse-Bias Leakage Current Mechanisms in Metal/GaN Schottky Diodes

    Directory of Open Access Journals (Sweden)

    P. Pipinys

    2010-01-01

    Full Text Available Temperature-dependent reverse-bias current-voltage characteristics obtained by other researchers for Schottky diodes fabricated on GaN are reinterpreted in terms of phonon-assisted tunneling (PhAT model. Temperature dependence of reverse-bias leakage current is shown could be caused by the temperature dependence of electron tunneling rate from traps in the metal-semiconductor interface to the conduction band of semiconductor. A good fit of experimental data with the theory is received in a wide temperature range (from 80 K to 500 K using for calculation the effective mass of 0.222 me. and for the phonon energy the value of 70 meV. The temperature and bias voltages dependences of an apparent barrier height (activation energy are also explicable in the framework of the PhAT model.

  19. OPTICAL STORAGE MECHANISM AND HIGH-ORDER DIFFRACTION PROPERTIES OF NITROAZOBENZENE-CONTAINING POLYESTER FILMS

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Using Nd:YAG second harmonic pulse (100 ps), the optical storage properties of two novel polyesters, poly [4'-bis (N, N-oxyethylene) imino-4-nitroazobenzene succinyl] and poly [2'-chloro-4'-bis (N, N-oxyethylene) imino-4-nitroazobenzene succinyl] have been studied by multiwave mixing. The high-order diffractions of the orientation gratingsinduced by anisotropy via the reorientation of nitroazobenzene groups and optical information storage with long-term stability have been realized by multiwave mixing in their films. Up to 3rd order forward diffraction was detected in two wave mixing, while up to 4th order backward diffraction was observed in degenerated four wave mixing. The recording mechanism was explained by the trans-cis-trans isomerization cycles of azobenzene groups.The isomerization of these azobenzene groups probably undergoes with inversion mechanism under the experimental conditions. The information recorded in these films has been kept for more than 6 months.

  20. Reduced order variational multiscale enrichment method for thermo-mechanical problems

    Science.gov (United States)

    Zhang, Shuhai; Oskay, Caglar

    2017-06-01

    This manuscript presents the formulation and implementation of the reduced order variational multiscale enrichment (ROVME) method for thermo-mechanical problems. ROVME is extended to model the inelastic behavior of heterogeneous structures, in which the constituent properties are temperature sensitive. The temperature-dependent coefficient tensors of the reduced order method are approximated in an efficient manner, retaining the computational efficiency of the reduced order model in the presence of spatial/temporal temperature variations. A Newton-Raphson iterative scheme is formulated and implemented for the numerical evaluation of nonlinear system of equations associated with the proposed ROVME method. Numerical verifications are performed to assess the efficiency and accuracy of the proposed computational framework. The results of the verifications reveal that ROVME retains reasonable accuracy and achieves high efficiency in the presence of hermo-mechanical loads.

  1. Electrocatalytic mechanism of reversible hydrogen cycling by enzymes and distinctions between the major classes of hydrogenases

    OpenAIRE

    Hexter, Suzannah V.; Grey, Felix; Happe, Thomas; Climent, Victor; Armstrong, Fraser A.

    2012-01-01

    The extraordinary ability of Fe- and Ni-containing enzymes to catalyze rapid and efficient H+/H2 interconversion—a property otherwise exclusive to platinum metals—has been investigated in a series of experiments combining variable-temperature protein film voltammetry with mathematical modeling. The results highlight important differences between the catalytic performance of [FeFe]-hydrogenases and [NiFe]-hydrogenases and justify a simple model for reversible catalytic electron flow in enzymes...

  2. Mechanisms and Processes Leading to Reverse Zoning in the Andong Granitoid Pluton, Andong Batholith, Korea

    Institute of Scientific and Technical Information of China (English)

    Sang Koo HWANG

    2002-01-01

    The Andong pluton consists of comagmatic granitoid rocks which constitute outstanding examples of reversely zoned granitoids. The pluton has three lithofacies: hornblende biotite tonalite, biotite granodiorite and porphyritic biotite granite. The zoned pattern forms by locating a tonalite core containing high-temperature mafic assemblages in central part,granodiorite rims in marginal part, and a porphyritic granite cap containing more felsic assemblages in topside of the pluton.Mineral abundances as well as bulk compositions of the granitoids indicate that the interior is enriched in mafic minerals and that it shows higher contents of oxides than the margin and topside. The compositional gradients change gradually with continuity between the lithofacies. The regular compositional variations within the pluton support the argument that the pluton behaved as an individual petrochemical system. Model abundances of the granitoids are in agreement with the bulk compositional gradients, suggesting that no significant interaction with country rocks occurred. Remobilization (resurgence) of deeper parts of the system into the more felsic magmas of the chamber explains the reverse zoning. Fractional crystallization was of importance and probably accounts for the selective removal of the settling phases. The Andong pluton is an example of reversely zoned plutons related by remobilization of more mafic but consanguineous magmas. Large-scale upwelling occurred in the pluton leading to the present arrangement of three lithofacies. It is conceivable that remnants of the reverse zoning become more difficult to discern as the plutonic rocks reach the latest stages of their evolution. In this case, the Andong pluton represents an earlier stage in the evolution of a felsic system that is usually represented by the final stages in normally zoned plutons.

  3. Mechanism of tension generation in muscle: an analysis of the forward and reverse rate constants.

    Science.gov (United States)

    Davis, Julien S; Epstein, Neal D

    2007-04-15

    Tension generation in muscle occurs during the attached phase of the ATP-powered cyclic interaction of myosin heads with thin filaments. The transient nature of tension-generating intermediates and the complexity of the mechanochemical cross-bridge cycle have impeded a quantitative description of tension generation. Recent experiments performed under special conditions yielded a sigmoidal dependence of fiber tension on temperature--a unique case that simplifies the system to a two-state transition. We have applied this two-state analysis to kinetic data obtained from biexponential laser temperature-jump tension transients. Here we present the forward and reverse rate constants for de novo tension generation derived from analysis of the kinetics of the fast laser temperature-jump phase tau(2) (equivalent of the length-jump phase 2(slow)). The slow phase tau(3) is temperature-independent indicating coupling to rather than a direct role in, de novo tension generation. Increasing temperature accelerates the forward, and slows the reverse, rate constant for the creation of the tension-generating state. Arrhenius behavior of the forward and anti-Arrhenius behavior of the reverse rate constant is a kinetic signature of multistate multipathway protein-folding reactions. We conclude that locally unfolded tertiary and/or secondary structure of the actomyosin cross-bridge mediates the power stroke.

  4. Design Paradigm Utilizing Reversible Diels-Alder Reactions to Enhance the Mechanical Properties of 3D Printed Materials.

    Science.gov (United States)

    Davidson, Joshua R; Appuhamillage, Gayan A; Thompson, Christina M; Voit, Walter; Smaldone, Ronald A

    2016-07-06

    A design paradigm is demonstrated that enables new functional 3D printed materials made by fused filament fabrication (FFF) utilizing a thermally reversible dynamic covalent Diels-Alder reaction to dramatically improve both strength and toughness via self-healing mechanisms. To achieve this, we used as a mending agent a partially cross-linked terpolymer consisting of furan-maleimide Diels-Alder (fmDA) adducts that exhibit reversibility at temperatures typically used for FFF printing. When this mending agent is blended with commercially available polylactic acid (PLA) and printed, the resulting materials demonstrate an increase in the interfilament adhesion strength along the z-axis of up to 130%, with ultimate tensile strength increasing from 10 MPa in neat PLA to 24 MPa in fmDA-enhanced PLA. Toughness in the z-axis aligned prints increases by up to 460% from 0.05 MJ/m(3) for unmodified PLA to 0.28 MJ/m(3) for the remendable PLA. Importantly, it is demonstrated that a thermally reversible cross-linking paradigm based on the furan-maleimide Diels-Alder (fmDA) reaction can be more broadly applied to engineer property enhancements and remending abilities to a host of other 3D printable materials with superior mechanical properties.

  5. Magnetization arrangement of hard magnetic phases and mechanism of magnetization and reversal magnetization of nano-composite magnets

    Institute of Scientific and Technical Information of China (English)

    LIU Xin-cai; XIE Ren; PAN Jing

    2009-01-01

    During the process of directional solidification, laser remelting/solidification in the layer on sintered magnets, die-upsetting of cast magnets, or die-upsetting of nano-composites, the arrangements of the easy-magnetization-axes of the hard magnetic phases (Nd_2Fe_(14)B, SmCo_5 or Sm_2Co_(17) type) in their designed directions have been studied. In Fe-Pt nano-composite magnets, attempts have been taken to promote phase transformation from disordered, soft magnetic A1 to ordered, hard magnetic L_(10) FePt phase at reduced temperatures. The dependence of the magnetization and reversal magnetization processes on the microstructures, involving the morphology and three critical sizes of particles of the FePt nano-composite magnets, are summarized. With the decrease of the nominal thickness of the anisotropic FePt film epitaxially grown on the single crystal MgO (001) substrate, the reversal magnetization process firstly changes from full domain wall displacement to partial magnetic wall pinning related to the morphology change, where the coercive force increases abruptly. The reversal magnetization process secondly changes from magnetic wall pinning to incoherent magnetization rotation associated with the particles being below the first critical size at which multi-domain particles turn into single domain ones, where the coercive force is still increased. And the reversal magnetization mode thirdly changes from incoherent to coherent rotation referred to the second critical size, where the increase of the coercive force keeps on. However, when the particle size decreases to approach the third critical size where the particles turn into the supperparamagnetic state, the coercive force begins to decrease due to the interplay of the size effect and the incomplete ordering induced by the size effect. Meanwhile, due to the size effect, Curie temperature of the ultra-small FePt particles reduces.

  6. Translation of Time-Reversal Violation in the Neutral K-Meson System into a Table-Top Mechanical System

    CERN Document Server

    Reiser, Andreas; Stiewe, Juergen

    2012-01-01

    Weak interactions break time-reversal (T) symmetry in the two-state system of neutral K mesons. We present and discuss a two-state mechanical system, a Foucault-type pendulum on a rotating table, for a full representation of K0 K0bar transitions by the pendulum motions including T violation. The pendulum moves with two different oscillation frequencies and two different magnetic dampings. Its equation of motion is identical with the differential equation for the real part of the CPT-symmetric K-meson wave function. The pendulum is able to represent microscopic CP and T violation with CPT symmetry owing to the macroscopic Coriolis force which breaks the symmetry under reversal-of-motion. Video clips of the pendulum motions are shown as supplementary material.

  7. Translation of time-reversal violation in the neutral K-meson system into a table-top mechanical system

    Science.gov (United States)

    Reiser, Andreas; Schubert, Klaus R.; Stiewe, Jürgen

    2012-08-01

    Weak interactions break time-reversal (T) symmetry in the two-state system of neutral K-mesons. We present and discuss a two-state mechanical system, i.e. a Foucault-type pendulum on a rotating table, for a full representation of {K^0}{{\\overlineK}{}^0} transitions by the pendulum motions including T violation. The pendulum moves with two different oscillation frequencies and two different magnetic dampings. Its equation of motion is identical to the differential equation for the real part of the CPT-symmetric K-meson wavefunction. The pendulum is able to represent microscopic CP and T violation with CPT symmetry owing to the macroscopic Coriolis force, which breaks the symmetry under reversal-of-motion. Video clips of the pendulum motions are given as supplementary material.

  8. A reversible hydrogen storage mechanism for sodium alanate: the role of alanes and the catalytic effect of the dopant

    Energy Technology Data Exchange (ETDEWEB)

    Walters, R. Tom [707 Cardinal Drive, Aiken, SC 29803 (United States)]. E-mail: jdtwalters@mindspring.com; Scogin, John H. [707 Cardinal Drive, Aiken, SC 29803 (United States)

    2004-10-06

    We propose a reversible hydrogen storage mechanism for cycled sodium alanate. The individual mechanistic reaction steps for the decomposition reaction derive a set of time-dependent differential equations that simultaneously produce the evolution plots for each species. These plots reproduce several aspects of in situ X-ray diffraction (XRD) data, as well as the measured relative composition of selected decomposition samples at various extents of reaction. The presence of alanes facilitates both the decomposition and reformation of sodium alanate based on the principle of microscopic reversibility. A major role for the titanium dopant in catalyzed sodium alanate dynamics may be alloy formation at or near the surface of bulk aluminum that facilitates the formation and sorption properties of alanes.

  9. Formation mechanism of ordered stress-relief patterns in a free sustained Cu film system

    Institute of Scientific and Technical Information of China (English)

    Chen Miao-Gen; Xie Jian-Ping; Jin Jin-Sheng; Xia A-Gen; Ye Gao-Xiang

    2008-01-01

    A nearly free sustained copper (Cu) film system has been successfully fabricated by thermal evaporation deposition of Cu atoms on silicone oil surfaces,and a characteristic ordered pattern has been systematically studied.The ordered pattern,namely,band,is composed of a large number of parallel key-formed domains with different width w but nearly uniform length L;its characteristic values of ω and L are very susceptible to the growth period,deposition rate and nominal film thickness.The formation mechanism of the ordered patterns is well explained in terms of the relaxation of the internal stress in the films,which is related to the nearly zero adhesion of the solid-liquid interface.By using a two-time deposition method,it is confirmed that the ordered patterns really form in the vacuum chamber.

  10. Reversed Crystal-Field Splitting and Spin-Orbital Ordering in α-Sr2CrO4

    Science.gov (United States)

    Ishikawa, Takashi; Toriyama, Tatsuya; Konishi, Takehisa; Sakurai, Hiroya; Ohta, Yukinori

    2017-03-01

    The origin of successive phase transitions observed in the layered perovskite α-Sr2CrO4 is studied by the density-functional-theory-based electronic structure calculation and mean-field analysis of the proposed low-energy effective model. We find that, despite the fact that the CrO6 octahedron is elongated along the c-axis of the crystal structure, the crystal-field level of nondegenerate 3dxy orbitals of the Cr ion is lower in energy than that of doubly degenerate 3dyz and 3dxz orbitals, giving rise to the orbital degrees of freedom in the system with a 3d2 electron configuration. We show that the higher (lower) temperature phase transition is caused by the ordering of the orbital (spin) degrees of freedom.

  11. Dual selection mechanisms drive efficient single-gene reverse genetics for rotavirus

    OpenAIRE

    Trask, Shane D.; Taraporewala, Zenobia F.; Boehme, Karl W.; Dermody, Terence S.; Patton, John T.

    2010-01-01

    Current methods for engineering the segmented double-stranded RNA genome of rotavirus (RV) are limited by inefficient recovery of the recombinant virus. In an effort to expand the utility of RV reverse genetics, we developed a method to recover recombinant viruses in which independent selection strategies are used to engineer single-gene replacements. We coupled a mutant SA11 RV encoding a temperature-sensitive (ts) defect in the NSP2 protein with RNAi-mediated degradation of NSP2 mRNAs to is...

  12. Brain mechanisms for predictive control by switching internal models: implications for higher-order cognitive functions.

    Science.gov (United States)

    Imamizu, Hiroshi; Kawato, Mitsuo

    2009-07-01

    Humans can guide their actions toward the realization of their intentions. Flexible, rapid and precise realization of intentions and goals relies on the brain learning to control its actions on external objects and to predict the consequences of this control. Neural mechanisms that mimic the input-output properties of our own body and other objects can be used to support prediction and control, and such mechanisms are called internal models. We first summarize functional neuroimaging, behavioral and computational studies of the brain mechanisms related to acquisition, modular organization, and the predictive switching of internal models mainly for tool use. These mechanisms support predictive control and flexible switching of intentional actions. We then review recent studies demonstrating that internal models are crucial for the execution of not only immediate actions but also higher-order cognitive functions, including optimization of behaviors toward long-term goals, social interactions based on prediction of others' actions and mental states, and language processing. These studies suggest that a concept of internal models can consistently explain the neural mechanisms and computational principles needed for fundamental sensorimotor functions as well as higher-order cognitive functions.

  13. Exterior beam-column joint study with non-conventional reinforcement detailing using mechanical anchorage under reversal loading

    Indian Academy of Sciences (India)

    S Rajagopal; S Prabavathy

    2014-10-01

    Reinforced concrete structures beam-column joints are the most critical regions in seismic prone areas. Proper reinforcement anchorage is essential to enhance the performance of the joints. An attempt has been made to appraise the performance of the anchorages and joints. The anchorages are detailed as per ACI-352 (mechanical anchorages), ACI-318 (conventional bent hooks) and IS-456 (conventional full anchorage). The joints are detailed without confinement in group-I and with additional X-cross bar in group-II. To assess the seismic performance, the specimens are assembled into two groups of three specimens each and were tested under reversal loading, The specimen with T-type mechanical anchorage (Headed bar) and T-type mechanical anchorage combination with X-cross bar exhibited significant improvement in seismic performance: load-displacement capacity, displacement ductility, stiffness degradation, controlled crack capacity in the joint shear panel and also reduced congestion of reinforcement in joint core.

  14. The physics mechanisms of light and heavy flavor $v_{2}$ and mass ordering in AMPT

    CERN Document Server

    Li, Hanlin; Wang, Fuqiang

    2016-01-01

    A Multi-Phase Transport (AMPT) model has been shown to describe experimental data well, such as the bulk properties of particle spectra and elliptic anisotropy ($v_{2}$) in heavy ion collisions. Recent studies have shown that AMPT describes the $v_{2}$ data in small system collisions as well. In these proceedings, we first investigate the origin of the mass ordering of identified hadrons $v_{2}$ in heavy ion as well as small system collisions. We then study the production mechanism of the charm $v_{2}$ in light of the escape mechanism for the light quark $v_{2}$.

  15. Fourth-order split monopole perturbation solutions to the Blandford-Znajek mechanism

    CERN Document Server

    Pan, Zhen

    2015-01-01

    The Blandford-Znajek (BZ) mechanism describes a physical process for the energy extraction from a spinning black hole (BH), which is believed to power a great variety of astrophysical sources, such as active galactic nuclei (AGNs) and Gamma ray bursts (GRBs). The only known analytic solution to the BZ mechanism is a split monopole perturbation solution up to $O(a^2)$, where $a$ is the spin parameter of a Kerr black hole. In this paper, we extend the monopole solution to higher order $\\sim O(a^4)$. We carefully investigate the structure of the BH magnetosphere, including the angular velocity of magnetic field lines $\\Omega$, the toroidal magnetic field $B^\\phi$ as well as the poloidal electric current $I$. In addition, the relevant energy extraction rate $\\dot E$ and the stability of this high-order monopole perturbation solution are also examined.

  16. Order-Disorder Phase Transition and Dielectric Mechanism in Relaxor Ferroelectrics

    Institute of Scientific and Technical Information of China (English)

    WU Zhongqing; LIU Zhirong; GU Binglin

    2001-01-01

    An overview is presented on the order-disorder structural transitions and the dielectric mechanism in the complex-perovskite type relaxor ferroelectrics,I.e.,the relaxors.Emphasis is put on the theoretical understanding of the structural transitions,the macroscopic dielectric properties,and the relationship between them. The influences of the composition,the temperature,and the atomic interactions on the order-disorder microstructures can be well understood in the cluster-variation-method calculations.The criterion drawn from theoretical analysis is successful in predicting the order-disorder structure of relaxors.Among various physical models about relaxers,the dipole glassy model that described the dielectric response as the thermally activated flips of the local spontaneous polarization under random interactions is discussed in details.The Monte Carlo simulation results of this model are consistent with the linear and nonlinear experiments of relaxors.

  17. Structural Characterization and Ordering Transformation of Mechanically Alloyed Nanocrystalline Fe-28Al Powder

    Directory of Open Access Journals (Sweden)

    Lima Amiri Talischi

    2016-12-01

    Full Text Available The synthesis of nanocrystalline Fe3Al powder by mechanical alloying as well as the structural ordering of the synthesized Fe3Al particles during the subsequent thermal analysis were investigated. Mechanical alloying was performed up to 100 hours using a planetary ball mill apparatus with rotational speed of 300 rpm under argon atmosphere at ambient temperature. The synthesized powders were characterized using X-ray diffraction, SEM observations and differential scanning calorimetry (DSC. The results show that the A2-type Fe3Al with disordered bcc structure is only formed after 70 hours milling. The corresponding lattice strain, mean crystallite and particle sizes for the 70 hours milled Fe3Al powder were determined as 2.5%, 10 and 500 nm, respectively. The subsequent heating during DSC causes a DO3-type Fe3Al ordering in 70 and 100 hours milled powders, however in 40 hours milled powder it only assists for the formation of disordered solid solution. Longer milling time induces a large amount of lattice strain in Fe3Al powder particles and consequently facilitates the atomic diffusion thus decreases the activation energy of ordering. The activation energy for ordering transformation of 100 hours Fe3Al milled powder was calculated as 152.1 kJ/mole which is about 4 kJ/mole lower than that for 70 hours milled powder.

  18. Mussel-inspired reversible metal-coordinate bonds as a pathway towards temporal control over the mechanical hierarchy of soft materials

    Science.gov (United States)

    Grindy, Scott; Learsch, Robert; Holten-Andersen, Niels

    2015-03-01

    Dynamic, reversible crosslinks have been shown to specifically control the mechanical properties of a wide variety of mechanically tough and resilient biomaterials. Here, we show that reversible histidine-metal ion interactions, long thought to contribute to the strong mechanical properties and self-healing nature of mussel byssal threads, can be used to control and engineer the hierarchical mechanical properties of model polyethylene glycol hydrogels orthogonally from the spatial structure of the material. We delve into the physics underlying these types of materials to properly understand how to explicitly engineer the mechanical properties of tough soft materials by utilizing their temporal hierarchy.

  19. Stacking order dependent mechanical properties of graphene/MoS{sub 2} bilayer and trilayer heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Elder, Robert M., E-mail: robert.elder26.ctr@mail.mil, E-mail: mahesh.neupane.ctr@mail.mil; Neupane, Mahesh R., E-mail: robert.elder26.ctr@mail.mil, E-mail: mahesh.neupane.ctr@mail.mil; Chantawansri, Tanya L. [U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005 (United States)

    2015-08-17

    Transition metal dichalcogenides (TMDC) such as molybdenum disulfide (MoS{sub 2}) are two-dimensional materials that show promise for flexible electronics and piezoelectric applications, but their weak mechanical strength is a barrier to practical use. In this work, we perform nanoindentation simulations using atomistic molecular dynamics to study the mechanical properties of heterostructures formed by combining MoS{sub 2} with graphene. We consider both bi- and tri-layer heterostructures formed with MoS{sub 2} either supported or encapsulated by graphene. Mechanical properties, such as Young's modulus, bending modulus, ultimate tensile strength, and fracture strain, are extracted from nanoindentation simulations and compared to the monolayer and homogeneous bilayer systems. We observed that the heterostructures, regardless of the stacking order, are mechanically more robust than the mono- and bi-layer MoS{sub 2}, mainly due to the mechanical reinforcement provided by the graphene layer. The magnitudes of ultimate strength and fracture strain are similar for both the bi- and tri-layer heterostructures, but substantially larger than either the mono- and bi-layer MoS{sub 2}. Our results demonstrate the potential of graphene-based heterostructures to improve the mechanical properties of TMDC materials.

  20. ABC transporters as multidrug resistance mechanisms and the development of chemosensitizers for their reversal

    Directory of Open Access Journals (Sweden)

    Choi Cheol-Hee

    2005-10-01

    Full Text Available Abstract One of the major problems related with anticancer chemotherapy is resistance against anticancer drugs. The ATP-binding cassette (ABC transporters are a family of transporter proteins that are responsible for drug resistance and a low bioavailability of drugs by pumping a variety of drugs out cells at the expense of ATP hydrolysis. One strategy for reversal of the resistance of tumor cells expressing ABC transporters is combined use of anticancer drugs with chemosensitizers. In this review, the physiological functions and structures of ABC transporters, and the development of chemosensitizers are described focusing on well-known proteins including P-glycoprotein, multidrug resistance associated protein, and breast cancer resistance protein.

  1. Reaction Mechanisms for the Limited Reversibility of Li-O2 Chemistry in Organic Carbonate Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wu; Xu, Kang; Viswanathan, Vilayanur V.; Towne, Silas A.; Hardy, John S.; Xiao, Jie; Nie, Zimin; Hu, Dehong; Wang, Deyu; Zhang, Jiguang

    2011-11-15

    The Li-O2 chemistry in nonaqueous carbonate electrolytes and the underneath reason of its limited reversibility was exhaustively investigated. The discharge products collected from the air cathode in a Li-O2 battery at different depth of discharge (DOD) were systematically analyzed with X-ray diffraction. It is revealed that, independent of the discharge depth, lithium alkylcarbonate (either lithium propylenedicarbonate - LPDC, or lithium ethylenedicarbonate - LEDC, with other related derivatives) and lithium carbonate (Li2CO3) are always the main products, obviously originated from the electrolyte solvents propylene carbonate (PC) and ethylene carbonate (EC). These lithium alkylcarbonates are obviously generated from the single-electron reductive decomposition of the corresponding carbonate solvents initiated by the attack of superoxide radical anions. On the other hand, neither lithium peroxide (Li2O2) nor lithium oxide (Li2O) is detected. More significantly, from in situ gas chromatography/mass spectroscopy it is found that Li2CO3 and Li2O cannot be oxidized even when charged up to 4.6 V vs. Li/Li+, while LPDC, LEDC and Li2O2 are readily able to, with CO2 and CO released with the re-oxidation of LPDC and LEDC. It is therefore concluded that the quasi-reversibility of Li-O2 chemistry observed hitherto in an organic carbonate-based electrolyte is actually reliant on the formation of lithium alkylcarbonates through the reductive decomposition of carbonate solvents during discharge process and the subsequent oxidation of these same alkylcarbonates during charge process. It is the poor oxidizability of these alkylcarbonate species that constitutes the obstruction to an ideal rechargeable Li-O2 battery.

  2. MoO2-ordered mesoporous carbon hybrids as anode materials with highly improved rate capability and reversible capacity for lithium-ion battery.

    Science.gov (United States)

    Chen, Ailian; Li, Caixia; Tang, Rui; Yin, Longwei; Qi, Yongxin

    2013-08-28

    A novel hybrid of MoO2-ordered mesoporous carbon (MoO2-OMC) was prepared through a two-step solvothermal chemical reaction route. The electrochemical performances of the mesoporous MoO2-OMC hybrids were examined using galvanostatical charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) techniques. The MoO2-OMC hybrid exhibits significantly improved electrochemical performance of high reversible capacity, high-rate capability, and excellent cycling performance as an anode electrode material for Li ion batteries. It is revealed that the MoO2-OMC hybrid could deliver the first discharge capacity of 1641.8 mA h g(-1) with an initial Coulombic efficiency of 63.6%, and a reversible capacity as high as 1049.1 mA h g(-1) even after 50 cycles at a current density of 100 mA g(-1), much higher than the theoretical capacity of MoO2 (838 mA h g(-1)) and OMC materials. The MoO2-OMC hybrid demonstrates an excellent high rate capability with capacity of ∼600 mA h g(-1) even at a charge current density of 1600 mA g(-1) after 50 cycles, which is approximately 11.1 times higher than that of the OMC (54 mA h g(-1)) materials. The improved rate capability and reversible capacity of the MoO2-OMC hybrid are attributed to a synergistic reaction between the MoO2 nanoparticles and mesoporous OMC matrices. It is noted that the electrochemical performance of the MoO2-OMC hybrid is evidently much better than the previous MoO2-based hybrids.

  3. A High-order Eulerian-Lagrangian Finite Element Method for Coupled Electro-mechanical Systems

    Science.gov (United States)

    Brandstetter, Gerd

    The main focus of this work is on the development of a high-order Eulerian-Lagrangian finite element method for the simulation of electro-mechanical systems. The coupled problem is solved by a staggered scheme, where the mechanical motion is discretized by standard Lagrangian finite elements, and the electrical field is solved on a fixed Eulerian grid with embedded boundary conditions. Traditional Lagrangian-Lagrangian or arbitrary Lagrangian-Eulerian (ALE) methods encounter deficiencies, for example, when dealing with mesh distortion due to large deformations, or topology changes due to contacting bodies. The presented Eulerian-Lagrangian approach addresses these issues in a natural way. Within this context we develop a high-order immersed boundary discontinuous-Galerkin (IB-DG) method, which is shown to be necessary for (i) the accurate representation of the electrical gradient along nonlinear boundary features such as singular corners, and (ii) to achieve full convergence during the iterative global solution. We develop an implicit scheme based on the mid-point rule, as well as an explicit scheme based on the centered-difference method, with the incorporation of energy conserving, frictionless contact algorithms for an elastic-to-rigid-surface contact. The performance of the proposed method is assessed for several benchmark tests: the electro-static force vector around a singular corner, the quasi-static pull-in of an electro-mechanically actuated switch, the excitation of a carbon nanotube at resonance, and the cyclic impact simulation of a micro-electro-mechanical resonant-switch. We report improved accuracy for the high-order method as compared to low-order methods, and linear convergence in the iterative solution of the staggered scheme. Additionally, we investigate a Newton-Krylov shooting scheme in order to directly find cyclic steady states of electro-mechanical devices excited at resonance-- as opposed to a naive time-stepping from zero initial

  4. Forward and reverse transduction at the limit of sensitivity studied by correlating electrical and mechanical fluctuations in frog saccular hair cells.

    Science.gov (United States)

    Denk, W; Webb, W W

    1992-06-01

    The spontaneous fluctuations of the intracellular voltage and the position of the sensory hairbundle were measured concurrently using intracellular microelectrodes and an optical differential micro interferometer. Magnitude and frequency distribution of the hair bundles' spontaneous motion suggest that it consists mostly of Brownian motion. The electrical noise, however, exceeds the value expected for thermal Johnson noise by several orders of magnitude, and its frequency distribution reflects the transduction tuning properties of the hair cells. Frequently, a strong correlation was observed between the fluctuations of the hair bundle position and the intracellular electrical noise. From the properties of the correlation and from experiments involving mechanical stimulation we conclude that in most cases mechano-electrical transduction of the bundles' Brownian motion causes this correlation. Small signal transduction sensitivities ranged from 18 to 500 microV/nm. Bundle motion that was observed in response to current injection in more than half of the cells suggests the existence of a fast reverse (electro-mechanical) transduction mechanism to be common in these cells. The sensitivities could be as high as 600 pm of bundle deflection per millivolt of membrane potential change. In a significant minority (4 in 44) of cells, all showing excess electrical noise, we found 'non-causal' components of the electro-mechanical correlation, and in two of those cells narrow-band bundle motion in excess of their thermal motion at frequencies coincident with peaks in the intracellular noise was observed.

  5. An Integrated Theory of Adsorption and Partition Mechanism and Eash Contribution to Solute Retention in Reversed Phase Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    耿信笃; 弗莱德依瑞格涅尔

    2003-01-01

    With the combination of the the stoichiometric displacement model for retention (SDM-R) in reversed phase liquid chromatography (RPLC) and the stoichiometric displacement model for adsorption (SDM-A) in physical chemistry,the total number of moles of the re-solvated methanol of stationary phase side.nr,and that of solute side in the mobile phase,q,corresponding the one mole of the desorbing solute,were separately determined and referred as the characterization parameters of the contributions of the adsorption mechanism and partition mechanism to the solute retention,respectively.A chromatographic system of insulin,using mobile phase consisting of the pseudo-homologue of alcohols(methanol,ethanol and 2-propanol)-water and trifluoroacetic acid was employed.The maximum number of the methanol layers on the stationary phase surface was found to be 10.6,only 3 of which being valid in usual RPLC,traditionally referred as a volume process in partition mechanism.However,it still follows the SDM-R.Both of q and nr of insulin were found not to be zero,indicating that the retention mechanism of insulin is a mixed mode of partition mechanism and adsorption mechanism.When methanol is used as the organic modifier,the ratio of q/nr was 1.13,indicating the contribution to insulin retention due to partition mechanism being a bit greater than that due to adsorption mechanism.A linear relationship between q,or nr and the carbon number of the pseudo-homologue in the mobile phase was also found.As a methodology for investigating the retention mechanism retention and behavior of biopolymers.a homologue of organic solvents as the organic modifier in mobile phase has also been explored.

  6. Achieving reversibility of ultra-high mechanical stress by hydrogen loading of thin films

    Science.gov (United States)

    Hamm, M.; Burlaka, V.; Wagner, S.; Pundt, A.

    2015-06-01

    Nano-materials are commonly stabilized by supports to maintain their desired shape and size. When these nano-materials take up interstitial atoms, this attachment to the support induces mechanical stresses. These stresses can be high when the support is rigid. High stress in the nano-material is typically released by delamination from the support or by the generation of defects, e.g., dislocations. As high mechanical stress can be beneficial for tuning the nano-materials properties, it is of general interest to deduce how real high mechanical stress can be gained. Here, we show that below a threshold nano-material size, dislocation formation can be completely suppressed and, when delamination is inhibited, even the ultrahigh stress values of the linear elastic limit can be reached. Specifically, for hydrogen solved in epitaxial niobium films on sapphire substrate supports a threshold film thickness of 6 nm was found and mechanical stress of up to (-10 ± 1) GPa was reached. This finding is of basic interest for hydrogen energy applications, as the hydride stability in metals itself is affected by mechanical stress. Thus, tuning of the mechanical stress-state in nano-materials may lead to improved storage properties of nano-sized materials.

  7. Kinetic mechanism for HIV-1 neutralization by antibody 2G12 entails reversible glycan binding that slows cell entry.

    Science.gov (United States)

    Platt, Emily J; Gomes, Michelle M; Kabat, David

    2012-05-15

    Despite structural knowledge of broadly neutralizing monoclonal antibodies (NMAbs) complexed to HIV-1 gp120 and gp41 envelope glycoproteins, virus inactivation mechanisms have been difficult to prove, in part because neutralization assays are complex and were previously not understood. Concordant with recent evidence that HIV-1 titers are determined by a race between entry of cell-attached virions and competing inactivation processes, we show that NMAb 2G12, which binds to gp120 N-glycans with α (1, 2)-linked mannose termini and inhibits replication after passive transfer into patients, neutralizes by slowing entry of adsorbed virions. Accordingly, apparent neutralization is attenuated when a kinetically competing virus inactivation pathway is blocked. Moreover, removing 2G12 from media causes its dissociation from virions coupled to accelerated entry and restored infectivity, demonstrating the reversibility of neutralization. A difference between 2G12 dissociation and infectivity recovery rates implies that the inhibited complexes at virus-cell junctions contain several 2G12's that must dissociate before entry commences. Quantitative microscopy of 2G12 binding and dissociation from single virions and studies using a split CCR5 coreceptor suggest that 2G12 competitively inhibits interactions between gp120's V3 loop and the tyrosine sulfate-containing CCR5 amino terminus, thereby reducing assembly of complexes that catalyze entry. These results reveal a unique reversible kinetic mechanism for neutralization by an antibody that binds near a critical V3 region in the glycan shield of gp120.

  8. Martensite phase reversion-induced nano/ ultrafine grained AISI 304L stainless steel with magnificent mechanical properties

    Directory of Open Access Journals (Sweden)

    Mohammad Shirdel

    2015-06-01

    Full Text Available Austenitic stainless steels are extensively used in various applications requiring good corrosion resistance and formability. In the current study, the formation of nano/ ultrafine grained austenitic microstructure in a microalloyed AISI 304L stainless steel was investigated by the advanced thermomechanical process of reversion of strain-induced martensite. For this purpose, samples were subjected to heavy cold rolling to produce a nearly complete martensitic structure. Subsequently, a wide range of annealing temperatures (600 to 800°C and times (1 to 240 min were employed to assess the reversion behavior and to find the best annealing condition for the production of the nano/ultrafine grained austenitic microstructure. Microstructural characterizations have been performed using X-ray diffraction (XRD, scanning electron microscopy (SEM, and magnetic measurement, whereas the mechanical properties were assessed by tensile and hardness tests. After thermomechanical treatment, a very fine austenitic structure was obtained, which was composed of nano sized grains of ~ 85 nm in an ultrafine grained matrix with an average grain size of 480 nm. This microstructure exhibited superior mechanical properties: high tensile strength of about 1280 MPa with a desirable elongation of about 41%, which can pave the way for the application of these sheets in the automotive industry.

  9. Synthesis and operation of an FFT-decoupled fixed-order reversed-field pinch plasma control system based on identification data

    Science.gov (United States)

    Olofsson, K. Erik J.; Brunsell, Per R.; Witrant, Emmanuel; Drake, James R.

    2010-10-01

    Recent developments and applications of system identification methods for the reversed-field pinch (RFP) machine EXTRAP T2R have yielded plasma response parameters for decoupled dynamics. These data sets are fundamental for a real-time implementable fast Fourier transform (FFT) decoupled discrete-time fixed-order strongly stabilizing synthesis as described in this work. Robustness is assessed over the data set by bootstrap calculation of the sensitivity transfer function worst-case H_{\\infty} -gain distribution. Output tracking and magnetohydrodynamic mode m = 1 tracking are considered in the same framework simply as two distinct weighted traces of a performance channel output-covariance matrix as derived from the closed-loop discrete-time Lyapunov equation. The behaviour of the resulting multivariable controller is investigated with dedicated T2R experiments.

  10. A unified approach for a posteriori high-order curved mesh generation using solid mechanics

    Science.gov (United States)

    Poya, Roman; Sevilla, Ruben; Gil, Antonio J.

    2016-09-01

    The paper presents a unified approach for the a posteriori generation of arbitrary high-order curvilinear meshes via a solid mechanics analogy. The approach encompasses a variety of methodologies, ranging from the popular incremental linear elastic approach to very sophisticated non-linear elasticity. In addition, an intermediate consistent incrementally linearised approach is also presented and applied for the first time in this context. Utilising a consistent derivation from energy principles, a theoretical comparison of the various approaches is presented which enables a detailed discussion regarding the material characterisation (calibration) employed for the different solid mechanics formulations. Five independent quality measures are proposed and their relations with existing quality indicators, used in the context of a posteriori mesh generation, are discussed. Finally, a comprehensive range of numerical examples, both in two and three dimensions, including challenging geometries of interest to the solids, fluids and electromagnetics communities, are shown in order to illustrate and thoroughly compare the performance of the different methodologies. This comparison considers the influence of material parameters and number of load increments on the quality of the generated high-order mesh, overall computational cost and, crucially, the approximation properties of the resulting mesh when considering an isoparametric finite element formulation.

  11. Magnetization reversal mechanism in patterned (square to wave-like) Py antidot lattices

    Science.gov (United States)

    Tahir, N.; Zelent, M.; Gieniusz, R.; Krawczyk, M.; Maziewski, A.; Wojciechowski, T.; Ding, J.; Adeyeye, A. O.

    2017-01-01

    The effects of shape and geometry of antidot (square, bi-component, and wave-like) lattices (ADLs) on the magnetization reversal processes and magnetic anisotropy has been systematically investigated by magneto-optical Kerr effect based microscopy. Our experimental results were reproduced by micromagnetic simulations, which highlight the qualitative agreement with the experimental results. We have demonstrated that a small antidot in the center of a unit cell in the square ADL is sufficient to induce additional easy axes with large coercive fields. In wave-like patterns, narrow channels connecting smaller and larger antidots (bi-component ADL) further drastically change the anisotropy map, creating the high coercive fields along a wide angular range (90°) of directions parallel to the channels. In simulated results, we have observed formation of periodic domain structures in all ADLs, however, in the case of a wave-like pattern it is most regular and moreover two different periodic patterns are stabilized at different applied magnetic field values. The formation of 360° domain walls were also observed in wave-like ADL where these domains are formed along the lines connecting adjacent larger and smaller antidots, perpendicular to the channels. These findings point out the possibility of exploiting ADLs with complex unit cells in magnonic or spintronic applications.

  12. Interaction of α-Hexylcinnamaldehyde with a Biomembrane Model: A Possible MDR Reversal Mechanism.

    Science.gov (United States)

    Sarpietro, Maria Grazia; Di Sotto, Antonella; Accolla, Maria Lorena; Castelli, Francesco

    2015-05-22

    The ability of the naturally derived compound α-hexylcinnamaldehyde (1) to interact with biomembranes and to modulate their permeability has been investigated as a strategy to reverse multidrug resistance (MDR) in cancer cells. Dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles (MLVs) were used as biomembrane models, and differential scanning calorimetry was applied to measure the effect of 1 on the thermotropic behavior of DMPC MLVs. The effect of an aqueous medium or a lipid carrier on the uptake of 1 by the biomembrane was also characterized. Furthermore, taking into account that MDR is strictly regulated by redox signaling, the pro-oxidant and/or antioxidant effects of 1 were evaluated by the crocin-bleaching assay, in both hydrophilic and lipophilic environments. Compound 1 was uniformly distributed in the phospholipid bilayers and deeply interacted with DMPC MLVs, intercalating among the phospholipid acyl chains and thus decreasing their cooperativity. The lipophilic medium allowed the absorption of 1 into the phospholipid membrane. In the crocin-bleaching assay, the substance produced no pro-oxidant effects in both hydrophilic and lipophilic environments; conversely, a significant inhibition of AAPH-induced oxidation was exerted in hydrophilic medium. These results suggest a possible role of 1 as a chemopreventive and chemosensitizing agent for fighting cancer.

  13. Pyrimethamine-induced alterations in human lymphocytes in vitro. Mechanisms and reversal of the effect

    DEFF Research Database (Denmark)

    Bygbjerg, Ib Christian

    1985-01-01

    . The effects of PYR were completely corrected by low concentrations of folinic acid and high concentrations of folic acid, indicating that the basic mechanism of action of PYR is competitive blocking of dihydrofolate reductase. However, the effect of PYR was poorly corrected by exogenous thymidine; therefore...

  14. Agmatine reversed mechanical allodynia in a rat model of neuropathic pain

    Institute of Scientific and Technical Information of China (English)

    YANGHong-Ju; ZhAONan; GONGZheng-Hua; YUANWei-Xiou; LIYunFeng; LI-Jin; LUOZhi-Pu

    2004-01-01

    AIM: Agmatine is an endogenous neuromodulator present in the brain and spinal cord, agmatine has both NMDA receptor antagonist and NOS inhibitor activities, which may participate the pathological process in the neuropathic pain. The effect of agmatine on the mechanical allodynia in a rat model of the neuropathic pain was investigated in this experiment.

  15. Reversible Tailoring of Mechanical Properties of Carbon Nanotube Forests by Immersing in Solvents

    Science.gov (United States)

    2014-12-07

    School of Mechanical Engineering, Georgia Institute of Technology, 771 Ferst Drive, Atlanta, GA 30332, USA b Air Force Research Laboratory , Materials...copy the initial stiff part of the load–displacement curve. The sud - den change of slope and start of the plateau region is related to the formation of

  16. High-order state space simulation models of helicopter flight mechanics

    Science.gov (United States)

    Kim, Frederick D.; Celi, Roberto; Tischler, Mark B.

    1993-01-01

    This paper describes the formulation and validation of a high-order linearized mathematical model of helicopter flight mechanics, which includes rotor flap and lag degrees of freedom as well as inflow dynamics. The model is extracted numerically from an existing nonlinear, blade element, real-time simulation model. Extensive modifications in the formulation and solution process of the nonlinear model, required for a theoetically rigorous linearization, are described in detail. The validation results show that the linearized model successfully captures the coupled rotor-fuselage dynamics in the frequency band most critical for the design of advanced flight control systems. Additional results quantify the extent to which the order of the model can be reduced without loss of fidelity.

  17. A condensation-ordering mechanism in nanoparticle-catalyzed peptide aggregation.

    Directory of Open Access Journals (Sweden)

    Stefan Auer

    2009-08-01

    Full Text Available Nanoparticles introduced in living cells are capable of strongly promoting the aggregation of peptides and proteins. We use here molecular dynamics simulations to characterise in detail the process by which nanoparticle surfaces catalyse the self-assembly of peptides into fibrillar structures. The simulation of a system of hundreds of peptides over the millisecond timescale enables us to show that the mechanism of aggregation involves a first phase in which small structurally disordered oligomers assemble onto the nanoparticle and a second phase in which they evolve into highly ordered as their size increases.

  18. Grain growth by Ordered Coalescence of crystallites in Ceramics : Grain Growth Mechanisms, Microstructure Evolution and Sintering

    OpenAIRE

    Hu, Jianfeng

    2013-01-01

    Grain growth and densification process play the two most crucial roles on the microstructure evolution and the achieved performances during sintering of ceramics. In this thesis, the grain growth of SrTiO3, BaTiO3-SrTiO3 solid solutions and Si3N4 ceramics during spark plasma sintering (SPS) were investigated by electron microscopy. SrTiO3 ceramics starting from nanopowders were fabricated by SPS. A novel grain growth mechanism was discovered and named as ordered coalescence (OC) of nanocrysta...

  19. Reversal of bupivacaine-induced cardiac electrophysiologic changes by two lipid emulsions in anesthetized and mechanically ventilated piglets.

    Science.gov (United States)

    Candela, Damien; Louart, Guillaume; Bousquet, Philippe-Jean; Muller, Laurent; Nguyen, Micheline; Boyer, Jean-Christophe; Peray, Pascale A Fabbro; Goret, Lucie; Ripart, Jacques; Lefrant, Jean-Yves; de La Coussaye, Jean E

    2010-05-01

    Accidental IV administration of bupivacaine can compromise cardiovascular function by inducing lethal arrhythmias whose hemodynamic consequences may be alleviated by lipid emulsions. However, little is known about the electrophysiologic effects of lipid emulsions. In this study, we assessed whether 2 different lipid emulsions can reverse cardiac electrophysiologic impairment induced by the IV administration of bupivacaine in anesthetized and mechanically ventilated piglets. Bupivacaine (4 mg . kg(-1)) was injected over a 30-second period in 26 piglets. Thirty seconds after the end of bupivacaine injection, 1.5 mL . kg(-1) saline solution for the control group, and long-chain triglyceride emulsion (LCT group) or a mixture of long-chain and medium-chain triglyceride emulsion (LCT/MCT group) were infused over 1 minute. Cardiac conduction variables and hemodynamic variables were monitored for 30 minutes after injection. Bupivacaine induced similar electrophysiologic and hemodynamic changes. After 3 minutes, His ventricle intervals (median and interquartiles) were 100 (85-105), 45 (35-55), and 53 (48-73) milliseconds in the control, LCT, and LCT/MCT groups, respectively (P < 0.001 between control and both lipid emulsion groups). Lipid emulsions also reversed the effects on QRS duration, atrial-His, and PQ (the onset of the P wave to the Q wave of the QRS complex) intervals. LCT/MCT emulsion restored the decrease in maximal first derivative of left ventricular pressure (P < 0.01 after 3 minutes versus control group). LCT and LCT/MCT emulsions reversed the lengthening of His ventricle, QRS, atrial-His, and PQ intervals induced by the IV injection of 4 mg . kg(-1) bupivacaine.

  20. A short-range ordering in soft magnetic Fe-based metallic glasses studied by Mössbauer spectroscopy and Reverse Monte Carlo method

    Science.gov (United States)

    Babilas, Rafał; Mariola, Kądziołka-Gaweł; Burian, Andrzej; Temleitner, László

    2016-05-01

    Selected soft magnetic amorphous alloys Fe80B20, Fe70Nb10B20 and Fe62Nb8B30 were produced by the melt-spinning and characterized by X-ray diffraction (XRD), transmission Mössbauer spectroscopy (MS), Reverse Monte Carlo modeling (RMC) and relative magnetic permeability measurements. The Mössbauer spectroscopy allowed to study the local environments of the Fe-centered atoms in the amorphous structure of binary and ternary glassy alloys. The MS provided also information about the changes in the amorphous structure due to the modification of chemical composition by various boron and niobium content. The RMC simulation based on the structure factors determined by synchrotron XRD measurements was also used in modeling of the atomic arrangements and short-range order in Fe-based model alloys. Addition of boron and niobium in the ternary model alloys affected the disorder in as-cast state and also influenced on the number of nearest neighbor Fe-Fe atoms, consequently. The distributions of Fe- and B-centered coordination numbers showed that N=10, 9 and 8 are dominated around Fe atoms and N=9, 8 and 7 had the largest population around B atoms in the examined amorphous alloys. Moreover, the relationship between the content of the alloying elements, the local atomic ordering and the magnetic permeability (magnetic after-effects) was mentioned.

  1. Design of cryptographically secure AES like S-Box using second-order reversible cellular automata for wireless body area network applications.

    Science.gov (United States)

    Gangadari, Bhoopal Rao; Rafi Ahamed, Shaik

    2016-09-01

    In biomedical, data security is the most expensive resource for wireless body area network applications. Cryptographic algorithms are used in order to protect the information against unauthorised access. Advanced encryption standard (AES) cryptographic algorithm plays a vital role in telemedicine applications. The authors propose a novel approach for design of substitution bytes (S-Box) using second-order reversible one-dimensional cellular automata (RCA(2)) as a replacement to the classical look-up-table (LUT) based S-Box used in AES algorithm. The performance of proposed RCA(2) based S-Box and conventional LUT based S-Box is evaluated in terms of security using the cryptographic properties such as the nonlinearity, correlation immunity bias, strict avalanche criteria and entropy. Moreover, it is also shown that RCA(2) based S-Boxes are dynamic in nature, invertible and provide high level of security. Further, it is also found that the RCA(2) based S-Box have comparatively better performance than that of conventional LUT based S-Box.

  2. Web-based Hierarchical Ordering Mechanism (WHOM) tool for MODIS data from Terra

    Science.gov (United States)

    Sikder, M. S.; Eaton, P.; Leptoukh, G.; McCrimmon, N.; Zhou, B.

    2001-05-01

    At the NASA Goddard Earth Sciences (GES) Distributed Active Archive Center (DAAC), we have substantially enhanced the popular Web-based Hierarchical Ordering Mechanism (WHOM) to include data from the Earth Observing System (EOS). The GES DAAC archives unprecedented volumes of remotely sensed data and large number of geophysical products derived from the MODIS instrument on board Terra satellite, and distributes them to the world scientific and applications user community. These products are currently divided into three groups: Radiometric and Geolocation, Atmosphere, and Ocean data products. The so-called Terra-WHOM (http://acdisx.gsfc.nasa.gov/data/dataset/MODIS/index.html) is a GES DAAC developed search and order user interface which is a smaller segment of the WHOM interface that provides access to all other GES DAAC data holdings. Terra-WHOM specifically provides user access to MODIS data archived at the GES DAAC. It allows users to navigate through all the available data products and submit a data request with minimal effort. The WHOM modular design and hierarchical architecture makes this tool unique, user-friendly, and very efficient to complete the search and order. The main principle of WHOM is that it advertises the available data products, so, users always know what they can get. The WHOM design includes: simple point & click, flexible, web pages generated from templates, consistent look and feel throughout interface, and easy configuration management due to contents being encapsulated and separated from software. Modular search algorithms provide dynamic Spatial and Temporal search capability and return the search results as html pages using CGI scripts. In Terra-WHOM, calendar pages show the actual number of data granules archived for each day for high-resolution local scenes, and from there the user can go to a page showing the geo-coverage for every granule for a given day. This feature significantly optimizes user's effort for selecting data. The

  3. Towards Ordered Silicon Nanostructures through Self-Assembling Mechanisms and Processes

    Directory of Open Access Journals (Sweden)

    R. A. Puglisi

    2015-01-01

    Full Text Available The design and development of innovative architectures for memory storage and energy conversion devices are at the forefront of current research efforts driving us towards a sustainable future. However, issues related to the cost, efficiency, and reliability of current technologies are still severely limiting their overtake of the standard designs. The use of ordered nanostructured silicon is expected to overcome these limitations and push the advancement of the alternative technologies. Specifically, self-assembling of block copolymers has been recognized as a promising and cost-effective approach to organize silicon nanostructures. This work reviews some of the most important findings on block copolymer self-assembling and complements those with the results of new experimental studies. First of all, a quantitative analysis is presented on the ordering and fluctuations expected in the synthesis of silicon nanostructures by using standard synthesis methods like chemical vapour deposition. Then the effects of the several parameters guiding the ordering mechanisms in the block copolymer systems, such as film thickness, molecular weight, annealing conditions, solvent, and substrate topography are discussed. Finally, as a proof of concept, an in-house developed example application to solar cells is presented, based on silicon nanostructures resulting from self-assembling of block copolymers.

  4. First order mean field games - explicit solutions, perturbations and connection with classical mechanics

    KAUST Repository

    Gomes, Diogo A.

    2016-01-06

    We present recent developments in the theory of first-order mean-field games (MFGs). A standard assumption in MFGs is that the cost function of the agents is monotone in the density of the distribution. This assumption leads to a comprehensive existence theory and to the uniqueness of smooth solutions. Here, our goals are to understand the role of local monotonicity in the small perturbation regime and the properties of solutions for problems without monotonicity. Under a local monotonicity assumption, we show that small perturbations of MFGs have unique smooth solutions. In addition, we explore the connection between first-order MFGs and classical mechanics and KAM theory. Next, for non-monotone problems, we construct non-unique explicit solutions for a broad class of first-order mean-field games. We provide an alternative formulation of MFGs in terms of a new current variable. These examples illustrate two new phenomena: the non-uniqueness of solutions and the breakdown of regularity.

  5. Exchange Mechanisms in Long Range Ordered Thin Film Organic Magnetic Semiconductors

    Science.gov (United States)

    Rawat, N.; Headrick, R.; Furis, M.; McGill, S.; Kilanski, L.; Waterman, R.

    2014-03-01

    Magnetic exchange mechanisms in crystalline thin films of Metal Phthalocyanines (M-Pc) are explored using Magnetic Circular Dichroism (MCD) and SQUID measurements up to 10 T and 2K. Long range ordered thin films of organo-soluble derivatives of Co-Pc and Mn-Pc were fabricated using solution processing technique. In the case of Mn-Pc, our measurements show enhanced hybridization of ligand π-electronic states with the Mn d-orbitals. MCD active states beyond 1 μm have been observed for the first time, providing crucial information on the orbital arrangements of MPc's that result in competing (co-existing) long-range superexchange and indirect exchange reminiscent of RKKY. The evolution of Zeeman splitting of specific MCD-active states is very well described by enhanced effective π-electrons g-factors as large as 100, analogous to diluted magnetic semiconductors (DMS) systems. In Co-Pc MCD data indicates a weaker exchange interaction between delocalized charge carriers and d-like spin-polarized electrons, however SQUID measurements reveal magnetic ordering up to 180K. A comparison between Mn-Pc and Co-Pc and earlier results from the spin 1/2 Cu-Pc and their non-magnetic Zn-Pc counterpart, offers an interesting view on the role of long range order in magnetic interactions. NSF, MRI and CAREER programs: DMR- 0722451; DMR-0348354; DMR- 0821268; DMR-1056589.

  6. Towards understanding a mechanism for reversible hydrogen storage: theoretical study of transition metal catalysed dehydrogenation of sodium alanate.

    Science.gov (United States)

    Ljubić, Ivan; Clary, David C

    2010-04-28

    On the basis of density functional theory and coupled-cluster CCSD(T) calculations we propose a mechanism of the dehydrogenation of transition metal doped sodium alanate. Insertion of two early 3d-transition metals, scandium and titanium, both of which are promising catalysts for reversible hydrogen storage in light metal hydrides, is compared. The mechanism is deduced from studies on the decomposition of a model system consisting of one transition metal atom and two NaAlH(4) units. Subsequently, the significance of such minimal cluster model systems to the real materials is tested by embedding the systems into the surface of the NaAlH(4) crystal. It is found that the dehydrogenation proceeds via breaking of the bridge H-Al bond and consequent formation of intermediate coordination compounds in which the H(2) molecule is side-on (eta(2)-) bonded to the transition metal centre. The total barrier to the H(2) release is thus dependent upon both the strength of the Al-H bond to be broken and the depth of the coordinative potential. The analogous mechanism applies for the recognized three successive dehydrogenation steps. The gas-phase model structures embedded into the surface of the NaAlH(4) crystal exhibit an unambiguous kinetic stability and their general geometric features remain largely unchanged.

  7. Structural mechanism of reverse α → γ transformation and strengthening of Fe-Ni alloys

    Science.gov (United States)

    Sagaradze, V. V.; Kataeva, N. V.; Kabanova, I. G.; Zavalishin, V. A.; Valiullin, A. I.; Klyukina, M. F.

    2014-07-01

    Fe-32% Ni alloy subjected to slow heating to a temperature below A s at a rate of 0.01 K/min demonstrates the untwinning and appearance of an intermediate ɛ phase with an hcp lattice and lattice parameters a = 2.535, c = 4.132 Å, and c/a = 1.63. Slow heating to 430-490°C leads to the formation of nanocrystalline austenite enriched in nickel, which substantially increases the hardness of martensite. The formation of austenite in the Fe-32% Ni alloy, which is a mixture of martensite with 20-30% nanocrystalline austenite, during its rapid heating to 600°C occurs via the bulk mechanism with short-range atomic diffusion. In this case, the diffusion does not eliminate the concentration micro-inhomogeneity of the alloy in nickel but leads to the reorientation of γ-phase nanocrystals, almost eliminates the dislocation structure, and removes the strengthening by phase hardening.

  8. H2 O2-induced higher order chromatin degradation: A novel mechanism of oxidative genotoxicity

    Indian Academy of Sciences (India)

    Gregory W Konat

    2003-02-01

    The genotoxicity of reactive oxygen species (ROS) is well established. The underlying mechanism involves oxidation of DNA by ROS. However, we have recently shown that hydrogen peroxide (H2O2), the major mediator of oxidative stress, can also cause genomic damage indirectly. Thus, H2O2 at pathologically relevant concentrations rapidly induces higher order chromatin degradation (HOCD), i.e. enzymatic excision of chromatin loops and their oligomers at matrix-attachment regions. The activation of endonuclease that catalyzes HOCD is a signalling event triggered specifically by H2O2. The activation is not mediated by an influx of calcium ions, but resting concentrations of intracellular calcium ions are required for the maintenance of the endonuclease in an active form. Although H2O2-induced HOCD can efficiently dismantle the genome leading to cell death, under sublethal oxidative stress conditions H2O2-induced HOCD may be the major source of somatic mutations.

  9. Intelligent Integrated Control of Underactuated Mechanical Systems with Second-order Nonholonomic Constraints

    Institute of Scientific and Technical Information of China (English)

    Lai Xuzhi(赖旭芝); Wu Min; Cai Zixing; She Jinhua

    2003-01-01

    This paper describes an intelligent integrated control of an acrobot, which is an underactuated mechanical system with second-order nonholonomic constraints. The control combines a model-free fuzzy control, a fuzzy sliding-mode control and a model-based fuzzy control. The model-free fuzzy controller designed for the upswing ensures that the energy of the acrobot increases with each swing. Then the fuzzy sliding-mode controller is employed to control the movement that the acrobot enters the balance area from the swing-up area. The model-based fuzzy controller, which is based on a Takagi-Sugeno fuzzy model, is used to balance the acrobot. The stability of the fuzzy control system for balance control is guaranteed by a common symmetric positive matrix, which satisfies linear matrix inequalities.

  10. The reaction mechanism of methyl-coenzyme M reductase: how an enzyme enforces strict binding order.

    Science.gov (United States)

    Wongnate, Thanyaporn; Ragsdale, Stephen W

    2015-04-10

    Methyl-coenzyme M reductase (MCR) is a nickel tetrahydrocorphinoid (coenzyme F430) containing enzyme involved in the biological synthesis and anaerobic oxidation of methane. MCR catalyzes the conversion of methyl-2-mercaptoethanesulfonate (methyl-SCoM) and N-7-mercaptoheptanoylthreonine phosphate (CoB7SH) to CH4 and the mixed disulfide CoBS-SCoM. In this study, the reaction of MCR from Methanothermobacter marburgensis, with its native substrates was investigated using static binding, chemical quench, and stopped-flow techniques. Rate constants were measured for each step in this strictly ordered ternary complex catalytic mechanism. Surprisingly, in the absence of the other substrate, MCR can bind either substrate; however, only one binary complex (MCR·methyl-SCoM) is productive whereas the other (MCR·CoB7SH) is inhibitory. Moreover, the kinetic data demonstrate that binding of methyl-SCoM to the inhibitory MCR·CoB7SH complex is highly disfavored (Kd = 56 mM). However, binding of CoB7SH to the productive MCR·methyl-SCoM complex to form the active ternary complex (CoB7SH·MCR(Ni(I))·CH3SCoM) is highly favored (Kd = 79 μM). Only then can the chemical reaction occur (kobs = 20 s(-1) at 25 °C), leading to rapid formation and dissociation of CH4 leaving the binary product complex (MCR(Ni(II))·CoB7S(-)·SCoM), which undergoes electron transfer to regenerate Ni(I) and the final product CoBS-SCoM. This first rapid kinetics study of MCR with its natural substrates describes how an enzyme can enforce a strictly ordered ternary complex mechanism and serves as a template for identification of the reaction intermediates.

  11. A new second-order integration algorithm for simulating mechanical dynamic systems

    Science.gov (United States)

    Howe, R. M.

    1989-01-01

    A new integration algorithm which has the simplicity of Euler integration but exhibits second-order accuracy is described. In fixed-step numerical integration of differential equations for mechanical dynamic systems the method represents displacement and acceleration variables at integer step times and velocity variables at half-integer step times. Asymptotic accuracy of the algorithm is twice that of trapezoidal integration and ten times that of second-order Adams-Bashforth integration. The algorithm is also compatible with real-time inputs when used for a real-time simulation. It can be used to produce simulation outputs at double the integration frame rate, i.e., at both half-integer and integer frame times, even though it requires only one evaluation of state-variable derivatives per integration step. The new algorithm is shown to be especially effective in the simulation of lightly-damped structural modes. Both time-domain and frequency-domain accuracy comparisons with traditional integration methods are presented. Stability of the new algorithm is also examined.

  12. Effects of the Ordering of Natural Selection and Population Regulation Mechanisms on Wright-Fisher Models.

    Science.gov (United States)

    He, Zhangyi; Beaumont, Mark; Yu, Feng

    2017-07-05

    We explore the effect of different mechanisms of natural selection on the evolution of populations for one- and two-locus systems. We compare the effect of viability and fecundity selection in the context of the Wright-Fisher model with selection under the assumption of multiplicative fitness. We show that these two modes of natural selection correspond to different orderings of the processes of population regulation and natural selection in the Wright-Fisher model. We find that under the Wright-Fisher model these two different orderings can affect the distribution of trajectories of haplotype frequencies evolving with genetic recombination. However, the difference in the distribution of trajectories is only appreciable when the population is in significant linkage disequilibrium. We find that as linkage disequilibrium decays the trajectories for the two different models rapidly become indistinguishable. We discuss the significance of these findings in terms of biological examples of viability and fecundity selection, and speculate that the effect may be significant when factors such as gene migration maintain a degree of linkage disequilibrium. Copyright © 2017 He et al.

  13. Effects of the Ordering of Natural Selection and Population Regulation Mechanisms on Wright-Fisher Models

    Directory of Open Access Journals (Sweden)

    Zhangyi He

    2017-07-01

    Full Text Available We explore the effect of different mechanisms of natural selection on the evolution of populations for one- and two-locus systems. We compare the effect of viability and fecundity selection in the context of the Wright-Fisher model with selection under the assumption of multiplicative fitness. We show that these two modes of natural selection correspond to different orderings of the processes of population regulation and natural selection in the Wright-Fisher model. We find that under the Wright-Fisher model these two different orderings can affect the distribution of trajectories of haplotype frequencies evolving with genetic recombination. However, the difference in the distribution of trajectories is only appreciable when the population is in significant linkage disequilibrium. We find that as linkage disequilibrium decays the trajectories for the two different models rapidly become indistinguishable. We discuss the significance of these findings in terms of biological examples of viability and fecundity selection, and speculate that the effect may be significant when factors such as gene migration maintain a degree of linkage disequilibrium.

  14. The hydraulic mechanism in the hind wing veins of Cybister japonicus Sharp (order: Coleoptera

    Directory of Open Access Journals (Sweden)

    Jiyu Sun

    2016-06-01

    Full Text Available The diving beetles (Dytiscidae, Coleoptera are families of water beetles. When they see light, they fly to the light source directly from the water. Their hind wings are thin and fragile under the protection of their elytra (forewings. When the beetle is at rest the hind wings are folded over the abdomen of the beetle and when in flight they unfold to provide the necessary aerodynamic forces. In this paper, the unfolding process of the hind wing of Cybister japonicus Sharp (order: Coleoptera was investigated. The motion characteristics of the blood in the veins of the structure system show that the veins have microfluidic control over the hydraulic mechanism of the unfolding process. A model is established, and the hind wing extending process is simulated. The blood flow and pressure changes are discussed. The driving mechanism for hydraulic control of the folding and unfolding actions of beetle hind wings is put forward. This can assist the design of new deployable micro air vehicles and bioinspired deployable systems.

  15. Reversible Second Order Kinetics of Sorption-Desorption of Cr(VI Ion on Activated Carbon from Palm Empty Fruit Bunches

    Directory of Open Access Journals (Sweden)

    Iip Izul Falah

    2015-11-01

    Full Text Available Activated carbon (AC from palm empty fruit bunches has been prepared, and this material was then used to adsorb Cr(VI from a solution. Characterization of the AC was conducted by detection of its functional groups, determination of total volatile compounds (VC content and its iodine number. Study on sorption-desorption kinetics was conducted by comparing results of evaluations of several models with proposed reversible second order model using the data produced in this work. Results of the works showed that the AC had similar characters compared with the AC produced by previous researchers. Application of the kinetics models on sorption Cr(VI onto the AC showed that nearly all of the models gave a good linearity. However, only the proposed model had a good relation with Langmuir isotherm, with respectively sorption (ks and desorption (kd constants were 5.75 x 10-4 L.mg‑1.min-1 and 2.20 x 10-3 min-1; maximum sorption capacity, qm = 20.00 mg.g-1; and equilibrium constant, K from kinetics experiment (0.261 L.mg-1 was comparable with the result from the isotherm experiment (0.269 L.mg-1. Hence, using this model, kinetics and Langmuir parameters can probably be determined from a single kinetics data experiment.

  16. Diminished swelling of cross-linked aromatic oligoamide surfaces revealing a new fouling mechanism of reverse-osmosis membranes.

    Science.gov (United States)

    Ying, Wang; Kumar, Rajender; Herzberg, Moshe; Kasher, Roni

    2015-06-02

    Swelling of the active layer of reverse osmosis (RO) membranes has an important effect on permeate water flux. The effects of organic- and biofouling on the swelling of the RO membrane active layer and the consequent changes of permeate flux are examined here. A cross-linked aromatic oligoamide film that mimics the surface chemistry of an RO polyamide membrane was synthesized stepwise on gold-coated surfaces. Foulant adsorption to the oligoamide film and its swelling were measured with a quartz crystal microbalance, and the effects of fouling on the membrane's performance were evaluated. The foulants were extracellular polymeric substances (EPS) extracted from fouled RO membranes and organic compounds of ultrafiltration permeate (UFP) from a membrane bioreactor used to treat municipal wastewater. The adsorbed foulants affected the swelling of the cross-linked oligoamide film differently. EPS had little effect on the swelling of the oligoamide film, whereas UFP significantly impaired swelling. Permeate flux declined more rapidly under UFP fouling than it did under EPS. Foulant adsorption was shown to diminish swelling of the aromatic oligoamide surfaces. Among the already known RO membrane fouling mechanisms, a novel RO fouling mechanism is proposed, in which foulant-membrane interactions hinder membrane swelling and thus increase hydraulic resistance.

  17. Structure and magnetization reversal mechanism in L1{sub 0} FePt films with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.J. [Surface Physics State Laboratory and Department of Physics, Fudan University, Shanghai 200433 (China); Zheng Jianguo [Laboratory for Electron and X-ray Instrumentation, Calit2, University of California-Irvine, Irvine, CA 92697 (United States); Shi, Z., E-mail: shizhong@tongji.edu.cn [Surface Physics State Laboratory and Department of Physics, Fudan University, Shanghai 200433 (China); Department of Physics, Tongji University, Shanghai 200092 (China); Zhou, S.M. [Surface Physics State Laboratory and Department of Physics, Fudan University, Shanghai 200433 (China); Department of Physics, Tongji University, Shanghai 200092 (China); Sun, L. [Department of Mechanical Engineering and Texas Center for Superconductivity (TcSUH), University of Houston, Houston, Texas 77204 (United States); Du, J. [National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2012-06-30

    A series of L1{sub 0} Fe{sub 63}Pt{sub 37} films with controlled thickness (t{sub FM}) were deposited on MgO(100) substrates for microstructure and magnetization reversal mechanism study. X-ray diffraction measurements show that face-centered tetragonal (200) peak also exists in addition to face-centered tetragonal (002) one, and becomes weak for thick films. High resolution electron microscopy study reveals the existence of periodic misfit dislocations at the FePt/MgO interface and other types of defects such as twins and antiphase boundary inside the film. Out-of-plane initial magnetization shows a slow increase responding to the external magnetic field and then follows a steep increase. The out-of-plane coercivity H{sub C} at room temperature decreases with increasing t{sub FM} and increases when the angle {theta}{sub H} between the external magnetic field and the film normal direction increases. H{sub C} at {theta}{sub H} = 0 changes as a linear function of temperature for individual samples and the slope decreases with increasing t{sub FM}. In addition, magnetic viscosity measurements show that the fluctuation field at room temperature decreases with increasing t{sub FM}. These phenomena indicate that the magnetization reversal in the L1{sub 0} FePt films should be realized by the motion of weakly pinned domain wall and thus governed by the thermal activation model. The magnetization reversal thermal activation volume and corresponding energy increase with increasing t{sub FM}, as a result of the interactions between domain walls and structural defects can be attributed to the sample microstructural characteristic evolution with t{sub FM}. - Highlights: Black-Right-Pointing-Pointer A series of L1{sub 0} Fe{sub 63}Pt{sub 37} films with controlled thickness (t{sub FM}) were prepared. Black-Right-Pointing-Pointer Periodic misfit dislocations are observed at the FePt/MgO interface. Black-Right-Pointing-Pointer The dependence of H{sub C} on t{sub FM} and T is

  18. A tumor-promoting mechanism mediated by retrotransposon-encoded reverse transcriptase is active in human transformed cell lines

    Science.gov (United States)

    Sciamanna, Ilaria; Gualtieri, Alberto; Cossetti, Cristina; Osimo, Emanuele Felice; Ferracin, Manuela; Macchia, Gianfranco; Aricò, Eleonora; Prosseda, Gianni; Vitullo, Patrizia; Misteli, Tom; Spadafora, Corrado

    2013-01-01

    LINE-1 elements make up the most abundant retrotransposon family in the human genome. Full-length LINE-1 elements encode a reverse transcriptase (RT) activity required for their own retrotranpsosition as well as that of non-autonomous Alu elements. LINE-1 are poorly expressed in normal cells and abundantly in cancer cells. Decreasing RT activity in cancer cells, by either LINE-1-specific RNA interference, or by RT inhibitory drugs, was previously found to reduce proliferation and promote differentiation and to antagonize tumor growth in animal models. Here we have investigated how RT exerts these global regulatory functions. We report that the RT inhibitor efavirenz (EFV) selectively downregulates proliferation of transformed cell lines, while exerting only mild effects on non-transformed cells; this differential sensitivity matches a differential RT abundance, which is high in the former and undetectable in the latter. Using CsCl density gradients, we selectively identify Alu and LINE-1 containing DNA:RNA hybrid molecules in cancer but not in normal cells. Remarkably, hybrid molecules fail to form in tumor cells treated with EFV under the same conditions that repress proliferation and induce the reprogramming of expression profiles of coding genes, microRNAs (miRNAs) and ultraconserved regions (UCRs). The RT-sensitive miRNAs and UCRs are significantly associated with Alu sequences. The results suggest that LINE-1-encoded RT governs the balance between single-stranded and double-stranded RNA production. In cancer cells the abundant RT reverse-transcribes retroelement-derived mRNAs forming RNA:DNA hybrids. We propose that this impairs the formation of double-stranded RNAs and the ensuing production of small regulatory RNAs, with a direct impact on gene expression. RT inhibition restores the ‘normal’ small RNA profile and the regulatory networks that depend on them. Thus, the retrotransposon-encoded RT drives a previously unrecognized mechanism crucial to the

  19. A tumor-promoting mechanism mediated by retrotransposon-encoded reverse transcriptase is active in human transformed cell lines.

    Science.gov (United States)

    Sciamanna, Ilaria; Gualtieri, Alberto; Cossetti, Cristina; Osimo, Emanuele Felice; Ferracin, Manuela; Macchia, Gianfranco; Aricò, Eleonora; Prosseda, Gianni; Vitullo, Patrizia; Misteli, Tom; Spadafora, Corrado

    2013-12-01

    LINE-1 elements make up the most abundant retrotransposon family in the human genome. Full-length LINE-1 elements encode a reverse transcriptase (RT) activity required for their own retrotranpsosition as well as that of non-autonomous Alu elements. LINE-1 are poorly expressed in normal cells and abundantly in cancer cells. Decreasing RT activity in cancer cells, by either LINE-1-specific RNA interference, or by RT inhibitory drugs, was previously found to reduce proliferation and promote differentiation and to antagonize tumor growth in animal models. Here we have investigated how RT exerts these global regulatory functions. We report that the RT inhibitor efavirenz (EFV) selectively downregulates proliferation of transformed cell lines, while exerting only mild effects on non-transformed cells; this differential sensitivity matches a differential RT abundance, which is high in the former and undetectable in the latter. Using CsCl density gradients, we selectively identify Alu and LINE-1 containing DNA:RNA hybrid molecules in cancer but not in normal cells. Remarkably, hybrid molecules fail to form in tumor cells treated with EFV under the same conditions that repress proliferation and induce the reprogramming of expression profiles of coding genes, microRNAs (miRNAs) and ultraconserved regions (UCRs). The RT-sensitive miRNAs and UCRs are significantly associated with Alu sequences. The results suggest that LINE-1-encoded RT governs the balance between single-stranded and double-stranded RNA production. In cancer cells the abundant RT reverse-transcribes retroelement-derived mRNAs forming RNA:DNA hybrids. We propose that this impairs the formation of double-stranded RNAs and the ensuing production of small regulatory RNAs, with a direct impact on gene expression. RT inhibition restores the 'normal' small RNA profile and the regulatory networks that depend on them. Thus, the retrotransposon-encoded RT drives a previously unrecognized mechanism crucial to the

  20. Computational contribution to the electrophoretic enantiomer separation mechanism and migration order using modified β-cyclodextrins.

    Science.gov (United States)

    Cecilio Fonseca, Matheus; Santos da Silva, Ricky Cássio; Nascimento, Clebio Soares; Bastos Borges, Keyller

    2017-08-01

    Capillary electrophoresis (CE) is an extremely effective technique in many kinds of separations, including separation of enantiomers. Some additional techniques may be necessary to determine the enantiomer migration order (EMO) and also the mechanism involved in chiral recognition. This paper reports the development and optimization of a CE method for enantioseparation of racemic mixture of both R- and S-stereoisomers of tramadol (TRM) with a computational contribution for the EMO determination and the responsible mechanisms for chiral distinction. Parameters such as composition and concentration of background electrolyte (BGE) and type and concentration of cyclodextrins (CD) were evaluated. For calculations, a sequential methodology was used, resorting to semiempirical Parametric Model 3 (PM3) followed by calculations accomplished using density functional theory. The best results were obtained with sulfated-β-CD (s-β-CD) and carboxymethyl-β-cyclodextrin (cm-β-CD) as chiral selector. Calculations show that the inclusion of TRM is not a probable process due to the shape of the TRM molecule and the size CDs cavities. Therefore, the chiral recognition process occurs by the formation of association complexes between modified β-CD and groups of TRM molecules. The structural analysis of the fragments of complexes at a pH of 10 and a thermodynamic analysis of the complexes' formation process allows determining the EMO. Comparing results obtained experimentally and computationally, it seems that the developed method is adequate for separation of TRM enantiomers and the computational methodology is also adequate to get a sense of the system at a molecular level. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Transport mechanism of reverse surface leakage current in AlGaN/GaN high-electron mobility transistor with SiN passivation

    Institute of Scientific and Technical Information of China (English)

    郑雪峰; 张进成; 郝跃; 范爽; 陈永和; 康迪; 张建坤; 王冲; 默江辉; 李亮; 马晓华

    2015-01-01

    The transport mechanism of reverse surface leakage current in AlGaN/GaN high-electron mobility transistor (HEMT) becomes one of the most important reliability issues with the downscaling of feature size. In this paper, the research results show that the reverse surface leakage current in AlGaN/GaN HEMT with SiN passivation increases with the enhancement of temperature in a range from 298 K to 423 K. Three possible transport mechanisms are proposed and examined to explain the generation of reverse surface leakage current. By comparing the experimental data with the numerical transport models, it is found that neither Fowler–Nordheim tunneling nor Frenkel–Poole emission can describe the transport of reverse surface leakage current. However, good agreement is found between the experimental data and the two-dimensional variable range hopping (2D-VRH) model. Therefore, it is concluded that the reverse surface leakage current is dominated by the electron hopping through the surface states at barrier layer. Moreover, the activation energy of surface leakage current is extracted, which is around 0.083 eV. Finally, the SiN passivated HEMT with high Al composition and thin AlGaN barrier layer is also studied. It is observed that 2D-VRH still dominates the reverse surface leakage current and the activation energy is around 0.10 eV, which demonstrates that the alteration of AlGaN barrier layer does not affect the transport mechanism of reverse surface leakage current in this paper.

  2. Mechanism of Thermal Reversal of the (Fulvalene)tetracarbonyldiruthenium Photoisomerization: Toward Molecular Solar-Thermal Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Kanai, Y; Srinivasan, V; Meier, S K; Vollhardt, K P; Grossman, J C

    2010-02-18

    In the currently intensifying quest to harness solar energy for the powering of our planet, most efforts are centered around photoinduced generic charge separation, such as in photovoltaics, water splitting, other small molecule activation, and biologically inspired photosynthetic systems. In contrast, direct collection of heat from sunlight has received much less diversified attention, its bulk devoted to the development of concentrating solar thermal power plants, in which mirrors are used to focus the sun beam on an appropriate heat transfer material. An attractive alternative strategy would be to trap solar energy in the form of chemical bonds, ideally through the photoconversion of a suitable molecule to a higher energy isomer, which, in turn, would release the stored energy by thermal reversal. Such a system would encompass the essential elements of a rechargeable heat battery, with its inherent advantages of storage, transportability, and use on demand. The underlying concept has been explored extensively with organic molecules (such as the norbornadiene-quadricyclane cycle), often in the context of developing photoswitches. On the other hand, organometallic complexes have remained relatively obscure in this capacity, despite a number of advantages, including expanded structural tunability and generally favorable electronic absorption regimes. A highly promising organometallic system is the previously reported, robust photo-thermal fulvalene (Fv) diruthenium couple 1 {l_reversible} 2 (Scheme 1). However, although reversible and moderately efficient, lack of a full, detailed atom-scale understanding of its key conversion and storage mechanisms have limited our ability to improve on its performance or identify optimal variants, such as substituents on the Fv, ligands other than CO, and alternative metals. Here we present a theoretical investigation, in conjunction with corroborating experiments, of the mechanism for the heat releasing step of 2 {yields} 1 and

  3. Mechanisms associated with HIV-1 resistance to acyclovir by the V75I mutation in reverse transcriptase.

    Science.gov (United States)

    Tchesnokov, Egor P; Obikhod, Aleksandr; Massud, Ivana; Lisco, Andrea; Vanpouille, Christophe; Brichacek, Beda; Balzarini, Jan; McGuigan, Christopher; Derudas, Marco; Margolis, Leonid; Schinazi, Raymond F; Götte, Matthias

    2009-08-01

    It has recently been demonstrated that the anti-herpetic drug acyclovir (ACV) also displays antiviral activity against the human immunodeficiency virus type 1 (HIV-1). The triphosphate form of ACV is accepted by HIV-1 reverse transcriptase (RT), and subsequent incorporation leads to classical chain termination. Like all approved nucleoside analogue RT inhibitors (NRTIs), the selective pressure of ACV is associated with the emergence of resistance. The V75I mutation in HIV-1 RT appears to be dominant in this regard. By itself, this mutation is usually not associated with resistance to currently approved NRTIs. Here we studied the underlying biochemical mechanism. We demonstrate that V75I is also selected under the selective pressure of a monophosphorylated prodrug that was designed to bypass the bottleneck in drug activation to the triphosphate form (ACV-TP). Pre-steady-state kinetics reveal that V75I discriminates against the inhibitor at the level of catalysis, whereas binding of the inhibitor remains largely unaffected. The incorporated ACV-monophosphate (ACV-MP) is vulnerable to excision in the presence of the pyrophosphate donor ATP. V75I compromises binding of the next nucleotide that can otherwise provide a certain degree of protection from excision. Collectively, the results of this study suggest that ACV is sensitive to two different resistance pathways, which warrants further investigation regarding the detailed resistance profile of ACV. Such studies will be crucial in assessing the potential clinical utility of ACV and its derivatives in combination with established NRTIs.

  4. Flow mechanism of self-induced reversed limit-cycle wing rock for a chined forebody configuration

    Science.gov (United States)

    Shi, Wei; Deng, Xueying; Wang, Yankui; Li, Qian

    2015-11-01

    The wing rock phenomenon reduces the maneuverability and affects the flight safety of modern advanced fighters, such as the F-35, which have chined forebodies. Understanding the flow mechanism is critical to suppressing this phenomenon. In this study, experiments were conducted to reveal the motion and flow behavior over a chined forebody configuration. The tests were performed in a wind tunnel at an angle of attack of 50∘ with a Reynolds number of 1.87 × 105. Reversed limit-cycle oscillation was discovered in the free-to-roll tests. The unstable rolling moment around zero roll angle in the static case suggests that the model tends to be driven away from zero roll angle. Thus, the model cannot maintain its equilibrium at zero roll angle during free-to-roll motion. The unstable rolling moment is generated by the wing vortex structure above the upward wing, which is induced by the forebody asymmetric vortices. During wing rock, the wing vortex structure appears above the upward wing at a large roll angle after crossing zero roll angle owing to a time lag in the forebody vortex position, which is conducive to the motion. The forebody asymmetric vortices are thus the key to induce and maintain the motion.

  5. A short-range ordering in soft magnetic Fe-based metallic glasses studied by Mössbauer spectroscopy and Reverse Monte Carlo method

    Energy Technology Data Exchange (ETDEWEB)

    Babilas, Rafał, E-mail: rafal.babilas@polsl.pl [Institute of Engineering Materials and Biomaterials, Silesian University of Technology, Konarskiego St. 18a, 44-100 Gliwice (Poland); Mariola, Kądziołka-Gaweł [August Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4 St., 40-007 Katowice (Poland); Burian, Andrzej [August Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4 St., 40-007 Katowice (Poland); Silesian Center of Education and Interdisciplinary Research, 75 Pułku Piechoty St., 40-500 Chorzów (Poland); Temleitner, László [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, H-1525 Budapest (Hungary)

    2016-05-15

    Selected soft magnetic amorphous alloys Fe{sub 80}B{sub 20}, Fe{sub 70}Nb{sub 10}B{sub 20} and Fe{sub 62}Nb{sub 8}B{sub 30} were produced by the melt-spinning and characterized by X-ray diffraction (XRD), transmission Mössbauer spectroscopy (MS), Reverse Monte Carlo modeling (RMC) and relative magnetic permeability measurements. The Mössbauer spectroscopy allowed to study the local environments of the Fe-centered atoms in the amorphous structure of binary and ternary glassy alloys. The MS provided also information about the changes in the amorphous structure due to the modification of chemical composition by various boron and niobium content. The RMC simulation based on the structure factors determined by synchrotron XRD measurements was also used in modeling of the atomic arrangements and short-range order in Fe-based model alloys. Addition of boron and niobium in the ternary model alloys affected the disorder in as-cast state and also influenced on the number of nearest neighbor Fe–Fe atoms, consequently. The distributions of Fe- and B-centered coordination numbers showed that N=10, 9 and 8 are dominated around Fe atoms and N=9, 8 and 7 had the largest population around B atoms in the examined amorphous alloys. Moreover, the relationship between the content of the alloying elements, the local atomic ordering and the magnetic permeability (magnetic after-effects) was mentioned. - Highlights: • SRO was investigated by XRD, Mössbauer, RMC and magnetic measurements. • N=10,9,8 are dominated around Fe atoms for Fe{sub 80}B{sub 20}, Fe{sub 70}Nb{sub 10}B{sub 20} and Fe{sub 62}Nb{sub 8}B{sub 30}. • N=9, 8 and 7 had the largest population around B atoms. • Fe-centered clusters with N=12 indicating icosahedral atomic configurations. • Magnetic after-effects is sensitive to the SRO and concentration of free volume.

  6. Quantified Mechanical Properties of the Deltoid Muscle Using the Shear Wave Elastography: Potential Implications for Reverse Shoulder Arthroplasty.

    Directory of Open Access Journals (Sweden)

    Taku Hatta

    Full Text Available The deltoid muscle plays a critical role in the biomechanics of shoulders undergoing reverse shoulder arthroplasty (RSA. However, both pre- and postoperative assessment of the deltoid muscle quality still remains challenging. The purposes of this study were to establish a novel methodology of shear wave elastography (SWE to quantify the mechanical properties of the deltoid muscle, and to investigate the reliability of this technique using cadaveric shoulders for the purpose of RSA. Eight fresh-frozen cadaveric shoulders were obtained. The deltoid muscles were divided into 5 segments (A1, A2, M, P1 and P2 according to the muscle fiber orientation and SWE values were measured for each segment. Intra- and inter-observer reliability was evaluated using intraclass correlation coefficient (ICC. To measure the response of muscle tension during RSA, the humeral shaft was osteotomized and subsequently elongated by an external fixator (intact to 15 mm elongation. SWE of the deltoid muscle was measured under each stretch condition. Intra- and inter-observer reliability of SWE measurements for all regions showed 0.761-0.963 and 0.718-0.947 for ICC(2,1. Especially, SWE measurements for segments A2 and M presented satisfactory repeatability. Elongated deltoid muscles by the external fixator showed a progressive increase in passive stiffness for all muscular segments. Especially, SWE outcomes of segments A2 and M reliably showed an exponential growth upon stretching (R2 = 0.558 and 0.593. Segmental measurements using SWE could be reliably and feasibly used to quantitatively assess the mechanical properties of the deltoid muscle, especially in the anterior and middle portions. This novel technique based on the anatomical features may provide helpful information of the deltoid muscle properties during treatment of RSA.

  7. Reversible resistance induced by FLT3 inhibition: a novel resistance mechanism in mutant FLT3-expressing cells.

    Directory of Open Access Journals (Sweden)

    Ellen Weisberg

    Full Text Available Clinical responses achieved with FLT3 kinase inhibitors in acute myeloid leukemia (AML are typically transient and partial. Thus, there is a need for identification of molecular mechanisms of clinical resistance to these drugs. In response, we characterized MOLM13 AML cell lines made resistant to two structurally-independent FLT3 inhibitors.MOLM13 cells were made drug resistant via prolonged exposure to midostaurin and HG-7-85-01, respectively. Cell proliferation was determined by Trypan blue exclusion. Protein expression was assessed by immunoblotting, immunoprecipitation, and flow cytometry. Cycloheximide was used to determine protein half-life. RT-PCR was performed to determine FLT3 mRNA levels, and FISH analysis was performed to determine FLT3 gene expression.We found that MOLM13 cells readily developed cross-resistance when exposed to either midostaurin or HG-7-85-01. Resistance in both lines was associated with dramatically elevated levels of cell surface FLT3 and elevated levels of phosphor-MAPK, but not phospho-STAT5. The increase in FLT3-ITD expression was at least in part due to reduced turnover of the receptor, with prolonged half-life. Importantly, the drug-resistant phenotype could be rapidly reversed upon withdrawal of either inhibitor. Consistent with this phenotype, no significant evidence of FLT3 gene amplification, kinase domain mutations, or elevated levels of mRNA was observed, suggesting that protein turnover may be part of an auto-regulatory pathway initiated by FLT3 kinase activity. Interestingly, FLT3 inhibitor resistance also correlated with resistance to cytosine arabinoside. Over-expression of FLT3 protein in response to kinase inhibitors may be part of a novel mechanism that could contribute to clinical resistance.

  8. 市场倒逼机制对企业文化建设的影响%Effect of Mechanism of Market Reversed Pressure on Enterprise Culture Construction

    Institute of Scientific and Technical Information of China (English)

    刘军捷

    2015-01-01

    From the perspective of the effect of market reversed pressure mechanism on enterprises the following points are elaborated: firstly, the formation of the effect of market reversed pressure mechanism on enterprise culture;secondly, the design principle of enterprise culture transition forced by market mechanism;thirdly, the path of enterprise culture transition forced by market mechanism.%从市场倒逼机制对企业的影响视角思考:一、市场倒逼机制对企业文化影响的形成机理;二、市场机制倒逼企业文化转型设计的原则;三、市场倒逼企业文化转型的路径。

  9. Statistical mechanics of random geometric graphs: Geometry-induced first-order phase transition.

    Science.gov (United States)

    Ostilli, Massimo; Bianconi, Ginestra

    2015-04-01

    Random geometric graphs (RGGs) can be formalized as hidden-variables models where the hidden variables are the coordinates of the nodes. Here we develop a general approach to extract the typical configurations of a generic hidden-variables model and apply the resulting equations to RGGs. For any RGG, defined through a rigid or a soft geometric rule, the method reduces to a nontrivial satisfaction problem: Given N nodes, a domain D, and a desired average connectivity 〈k〉, find, if any, the distribution of nodes having support in D and average connectivity 〈k〉. We find out that, in the thermodynamic limit, nodes are either uniformly distributed or highly condensed in a small region, the two regimes being separated by a first-order phase transition characterized by a O(N) jump of 〈k〉. Other intermediate values of 〈k〉 correspond to very rare graph realizations. The phase transition is observed as a function of a parameter a∈[0,1] that tunes the underlying geometry. In particular, a=1 indicates a rigid geometry where only close nodes are connected, while a=0 indicates a rigid antigeometry where only distant nodes are connected. Consistently, when a=1/2 there is no geometry and no phase transition. After discussing the numerical analysis, we provide a combinatorial argument to fully explain the mechanism inducing this phase transition and recognize it as an easy-hard-easy transition. Our result shows that, in general, ad hoc optimized networks can hardly be designed, unless to rely to specific heterogeneous constructions, not necessarily scale free.

  10. Significance of first-order faults in folding mechanically isotropic layers: Evidence from the Sudbury Basin, Canada

    Science.gov (United States)

    Clark, Martin D.; Riller, Ulrich

    2017-02-01

    The Sudbury Basin is a non-cylindrical fold basin demarcated by the layered Sudbury Igneous Complex (SIC), the eastern part of which is transected by prominent curved faults. Folding of the SIC and adjacent rock units occurred in the brittle field and is peculiar due to its petrographically distinct, but initially mechanically similar layers. Overall, the layers are characterized by low levels of solid-state strain raising the question how the layer contacts acquired their curvature. We addressed this question by developing a G.I.S.-based workflow to analyze the orientation and slip vectors of the faults. Slip vectors form clusters of normal and reverse slip along a given fault. The clustering is best interpreted in terms of successive slip events during folding of the SIC. As the faults formed most likely as planar reverse faults prior to folding of the SIC they subsequently served as mechanically anisotropic elements to fold the SIC. The results contribute to (1) better understand the folding mechanisms of thick melt sheets in the upper crust, (2) explain apparently incompatible principal strain axes during progressive deformation, and (3) efficiently analyze the orientation and kinematics of fault zones close to the Earth's surface.

  11. Geometrical foundations of continuum mechanics an application to first- and second-order elasticity and elasto-plasticity

    CERN Document Server

    Steinmann, Paul

    2015-01-01

    This book illustrates the deep roots of the geometrically nonlinear kinematics of generalized continuum mechanics in differential geometry. Besides applications to first- order elasticity and elasto-plasticity an appreciation thereof is particularly illuminating for generalized models of continuum mechanics such as second-order (gradient-type) elasticity and elasto-plasticity.   After a motivation that arises from considering geometrically linear first- and second- order crystal plasticity in Part I several concepts from differential geometry, relevant for what follows, such as connection, parallel transport, torsion, curvature, and metric for holonomic and anholonomic coordinate transformations are reiterated in Part II. Then, in Part III, the kinematics of geometrically nonlinear continuum mechanics are considered. There various concepts of differential geometry, in particular aspects related to compatibility, are generically applied to the kinematics of first- and second- order geometrically nonlinear con...

  12. High order ADER schemes for a unified first order hyperbolic formulation of continuum mechanics: Viscous heat-conducting fluids and elastic solids

    Energy Technology Data Exchange (ETDEWEB)

    Dumbser, Michael, E-mail: michael.dumbser@unitn.it [Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento (Italy); Peshkov, Ilya, E-mail: peshkov@math.nsc.ru [Open and Experimental Center for Heavy Oil, Université de Pau et des Pays de l' Adour, Avenue de l' Université, 64012 Pau (France); Romenski, Evgeniy, E-mail: evrom@math.nsc.ru [Sobolev Institute of Mathematics, 4 Acad. Koptyug Avenue, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 2 Pirogova Str., 630090 Novosibirsk (Russian Federation); Zanotti, Olindo, E-mail: olindo.zanotti@unitn.it [Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento (Italy)

    2016-06-01

    Highlights: • High order schemes for a unified first order hyperbolic formulation of continuum mechanics. • The mathematical model applies simultaneously to fluid mechanics and solid mechanics. • Viscous fluids are treated in the frame of hyper-elasticity as generalized visco-plastic solids. • Formal asymptotic analysis reveals the connection with the Navier–Stokes equations. • The distortion tensor A in the model appears to be well-suited for flow visualization. - Abstract: This paper is concerned with the numerical solution of the unified first order hyperbolic formulation of continuum mechanics recently proposed by Peshkov and Romenski [110], further denoted as HPR model. In that framework, the viscous stresses are computed from the so-called distortion tensor A, which is one of the primary state variables in the proposed first order system. A very important key feature of the HPR model is its ability to describe at the same time the behavior of inviscid and viscous compressible Newtonian and non-Newtonian fluids with heat conduction, as well as the behavior of elastic and visco-plastic solids. Actually, the model treats viscous and inviscid fluids as generalized visco-plastic solids. This is achieved via a stiff source term that accounts for strain relaxation in the evolution equations of A. Also heat conduction is included via a first order hyperbolic system for the thermal impulse, from which the heat flux is computed. The governing PDE system is hyperbolic and fully consistent with the first and the second principle of thermodynamics. It is also fundamentally different from first order Maxwell–Cattaneo-type relaxation models based on extended irreversible thermodynamics. The HPR model represents therefore a novel and unified description of continuum mechanics, which applies at the same time to fluid mechanics and solid mechanics. In this paper, the direct connection between the HPR model and the classical hyperbolic–parabolic Navier

  13. Chemical order and selection of the mechanism for strain relaxation in epitaxial FePd(Pt) thin layers

    Science.gov (United States)

    Halley, D.; Marty, A.; Bayle-Guillemaud, P.; Gilles, B.; Attane, J. P.; Samson, Y.

    2004-11-01

    We observed that the relaxation mechanism of the epitaxial strain is dramatically dependent on the chemical ordering within the L10 structure in FePd(Pt) thin films. In disordered or weakly ordered layers, the relaxation takes place though perfect (1)/(2)[101] dislocations, whereas well-ordered films relax through the partial 1/6[112] Shockley dislocations, piled-up within microtwins, with a huge impact on both the morphology and the magnetic properties of the film. We show that the antiphase boundary energy is the key factor preventing the propagation of perfect dislocations in ordered alloys.

  14. High order ADER schemes for a unified first order hyperbolic formulation of continuum mechanics: Viscous heat-conducting fluids and elastic solids

    Science.gov (United States)

    Dumbser, Michael; Peshkov, Ilya; Romenski, Evgeniy; Zanotti, Olindo

    2016-06-01

    This paper is concerned with the numerical solution of the unified first order hyperbolic formulation of continuum mechanics recently proposed by Peshkov and Romenski [110], further denoted as HPR model. In that framework, the viscous stresses are computed from the so-called distortion tensor A, which is one of the primary state variables in the proposed first order system. A very important key feature of the HPR model is its ability to describe at the same time the behavior of inviscid and viscous compressible Newtonian and non-Newtonian fluids with heat conduction, as well as the behavior of elastic and visco-plastic solids. Actually, the model treats viscous and inviscid fluids as generalized visco-plastic solids. This is achieved via a stiff source term that accounts for strain relaxation in the evolution equations of A. Also heat conduction is included via a first order hyperbolic system for the thermal impulse, from which the heat flux is computed. The governing PDE system is hyperbolic and fully consistent with the first and the second principle of thermodynamics. It is also fundamentally different from first order Maxwell-Cattaneo-type relaxation models based on extended irreversible thermodynamics. The HPR model represents therefore a novel and unified description of continuum mechanics, which applies at the same time to fluid mechanics and solid mechanics. In this paper, the direct connection between the HPR model and the classical hyperbolic-parabolic Navier-Stokes-Fourier theory is established for the first time via a formal asymptotic analysis in the stiff relaxation limit. From a numerical point of view, the governing partial differential equations are very challenging, since they form a large nonlinear hyperbolic PDE system that includes stiff source terms and non-conservative products. We apply the successful family of one-step ADER-WENO finite volume (FV) and ADER discontinuous Galerkin (DG) finite element schemes to the HPR model in the stiff

  15. Regularity properties of fiber derivatives associated with higher-order mechanical systems

    Science.gov (United States)

    Colombo, Leonardo; Prieto-Martínez, Pedro Daniel

    2016-08-01

    The aim of this work is to study fiber derivatives associated to Lagrangian and Hamiltonian functions describing the dynamics of a higher-order autonomous dynamical system. More precisely, given a function in T∗T(k-1)Q, we find necessary and sufficient conditions for such a function to describe the dynamics of a kth-order autonomous dynamical system, thus being a kth-order Hamiltonian function. Then, we give a suitable definition of (hyper)regularity for these higher-order Hamiltonian functions in terms of their fiber derivative. In addition, we also study an alternative characterization of the dynamics in Lagrangian submanifolds in terms of the solutions of the higher-order Euler-Lagrange equations.

  16. Reverse blocking characteristics and mechanisms in Schottky-drain AlGaN/GaN HEMT with a drain field plate and floating field plates

    Science.gov (United States)

    Wei, Mao; Wei-Bo, She; Cui, Yang; Jin-Feng, Zhang; Xue-Feng, Zheng; Chong, Wang; Yue, Hao

    2016-01-01

    In this paper, a novel AlGaN/GaN HEMT with a Schottky drain and a compound field plate (SD-CFP HEMT) is presented for the purpose of better reverse blocking capability. The compound field plate (CFP) consists of a drain field plate (DFP) and several floating field plates (FFPs). The physical mechanisms of the CFP to improve the reverse breakdown voltage and to modulate the distributions of channel electric field and potential are investigated by two-dimensional numerical simulations with Silvaco-ATLAS. Compared with the HEMT with a Schottky drain (SD HEMT) and the HEMT with a Schottky drain and a DFP (SD-FP HEMT), the superiorities of SD-CFP HEMT lie in the continuous improvement of the reverse breakdown voltage by increasing the number of FFPs and in the same fabrication procedure as the SD-FP HEMT. Two useful optimization laws for the SD-CFP HEMTs are found and extracted from simulation results. The relationship between the number of the FFPs and the reverse breakdown voltage as well as the FP efficiency in SD-CFP HEMTs are discussed. The results in this paper demonstrate a great potential of CFP for enhancing the reverse blocking ability in AlGaN/GaN HEMT and may be of great value and significance in the design and actual manufacture of SD-CFP HEMTs. Project supported by the National Natural Science Foundation of China (Grant Nos. 61204085, 61334002, 61306017, 61474091, 61574112, and 61574110).

  17. Concept of sustained ordering and an ATP-related mechanism of life's origin

    National Research Council Canada - National Science Library

    Galimov, Erik M

    2009-01-01

    This paper shows that the steady state of a system of conjugated reactions, which are characterized by disproportionation of entropy and proceed in the domain of linear interactions, is an attractor of ordering...

  18. Crystallographic mechanism of inverse twinning in ordered β′-CuZn alloy

    Institute of Scientific and Technical Information of China (English)

    毛卫民

    2000-01-01

    The basic process of mechanical twinning in β’-CuZn phase, as an example of B2 structured metals, has been analyzed under the rolling stresses. The behavior of inverse twinning in B2 structured metals is discussed in terms of mechanics and crystallographic stability. It is shown that the inverse twinning could remain the B2 structure, and the resulting strains will have the lowest resistance during the rolling deformation of the polycrystalline.

  19. Crystallographic mechanism of inverse twinning in ordered β'-CuZn alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The basic process of mechanical twinning in β'-CuZn phase, as an example of B2 structured metals, has been analyzed under the rolling stresses. The behavior of inverse twinning in B2 structured metals is discussed in terms of mechanics and crystallographic stability. It is shown that the inverse twinning could remain the B2 structure, and the resulting strains will have the lowest resistance during the rolling deformation of the polycrystalline.

  20. [Reversal of adriamycin resistance by digoxin in human breast cancer cell line MCF-7/adriamycin and its mechanism].

    Science.gov (United States)

    Li, Bai-He; Yuan, Lei; Shi, Ran-Ran; Wang, Jian-Guo

    2015-12-25

    The aim of this study was to investigate the effects of digoxin on the chemoresistance of human breast cancer cell line MCF-7/adriamycin (ADR) and its underlying mechanism. MCF-7 and MCF-7/ADR cells were designated as control and ADR groups, respectively. MCF-7/ADR cells in ADR + digoxin group received 48 h of digoxin (10 nmol/L) treatment; MCF-7/ADR cells transfected with pLKO.1-shHIF-1α and pLKO.1-shcontrol plasmids were named shHIF-1α and shcontrol groups, respectively. CCK-8 assay was employed to detect the cytotoxic effect of ADR on MCF-7/ADR cells, and IC50 value and resistance index were calculated according to CCK-8. RT-PCR was used to measure the mRNA levels of hypoxia inducible factor-1α (HIF-1α) and multidrug resistance-1 (MDR1). Western blot was used to analyze the protein levels of HIF-1α and MDR1. Flow cytometry was used to determine the apoptosis. The result showed that the resistance index of MCF-7/ADR cells was 115.6, and it was reduced to 47.2 under the action of digoxin (P Digoxin reduced the protein levels of HIF-1α and MDR1, as well as the mRNA level of MDR1, but did not affect the mRNA level of HIF-1α. After HIF-1α gene was silenced, the protein levels of HIF-1α and MDR1 were down-regulated (P digoxin promoted cell apoptosis in both shcontrol and shHIF-1α groups, the difference between the two groups was not significant. In conclusion, the results suggest that digoxin may partially reverse the ADR resistance in human breast cancer cell line MCF-7/ADR by means of down-regulating the expression levels of HIF-1α and MDR1 and promoting apoptosis via HIF-1α-independent pathway.

  1. Reduced-Order Modeling of Parametrically Excited Micro-Electro-Mechanical Systems (MEMS

    Directory of Open Access Journals (Sweden)

    Sangram Redkar

    2010-01-01

    Full Text Available Reduced-order modeling is a systematic way of constructing models with smaller number of states that can capture the “essential dynamics” of the large-scale systems, accurately. In this paper, reduced-order modeling and control techniques for parametrically excited MEMS are presented. The techniques proposed here use the Lyapunov-Floquet (L-F transformation that makes the linear part of transformed equations time invariant. In this work, three model reduction techniques for MEMS are suggested. First method is simply an application of the well-known Guyan-like reduction method to nonlinear systems. The second technique is based on singular perturbation, where the transformed system dynamics is partitioned as fast and slow dynamics and the system of differential equations is converted into a differential algebraic (DAE system. In the third technique, the concept of invariant manifold for time-periodic systems is used. The “time periodic invariant manifold” based technique yields “reducibility conditions”. This is an important result because it helps us to understand the various types of resonances present in the system. These resonances indicate a tight coupling between the system states, and in order to retain the dynamic characteristics, one has to preserve all these “resonant” states in the reduced-order model. Thus, if the “reducibility conditions” are satisfied, only then a nonlinear order reduction based on invariant manifold approach is possible. It is found that the invariant manifold approach yields the most accurate results followed by the nonlinear projection and linear technique. These methodologies are general, free from small parameter assumptions, and can be applied to a variety of MEM systems like resonators, sensors and filters. The reduced-order models can be used for parametric study, sensitivity analysis and/or controller design. The controller design is based on the reduced-order system. Thus, first the

  2. The Analysi s of Incomplete Gear Reversing Mechanism Dynamics%不完全齿轮换向机构的动力学特性分析

    Institute of Scientific and Technical Information of China (English)

    王猛; 李长春; 田希杰

    2012-01-01

    在利用Pro/E4.0对不完全齿轮进行渐开线参数化建模的基础上,使用ADAMS软件对不完全齿轮自动换向机构进行动力学仿真分析,并研究了齿轮作用力和转矩的特性曲线。%In the use of Pro / E 4 on the incomplete gear involute parametric modeling based on ADAMS software, use of incomplete gear automatic reversing mechanism simulation analysis of dynamic is carried out, and the study of the gear force and torque characteristic curve. Base on the incomplete gear involute parametric modeling in the use of Pro/E 4.0, the incomplete gear automatic reversing mechanism simulation analysis of dynamic on ADAMS software is carried out, and the study of the gear force and torque characteristic curve.

  3. A partitioned model order reduction approach to rationalise computational expenses in nonlinear fracture mechanics

    Science.gov (United States)

    Kerfriden, P.; Goury, O.; Rabczuk, T.; Bordas, S.P.A.

    2013-01-01

    We propose in this paper a reduced order modelling technique based on domain partitioning for parametric problems of fracture. We show that coupling domain decomposition and projection-based model order reduction permits to focus the numerical effort where it is most needed: around the zones where damage propagates. No a priori knowledge of the damage pattern is required, the extraction of the corresponding spatial regions being based solely on algebra. The efficiency of the proposed approach is demonstrated numerically with an example relevant to engineering fracture. PMID:23750055

  4. Influence of time dependent longitudinal magnetic fields on the cooling process, exchange bias and magnetization reversal mechanism in FM core/AFM shell nanoparticles: a Monte Carlo study

    Science.gov (United States)

    Yüksel, Yusuf; Akıncı, Ümit

    2016-12-01

    Using Monte Carlo simulations, we have investigated the dynamic phase transition properties of magnetic nanoparticles with ferromagnetic core coated by an antiferromagnetic shell structure. Effects of field amplitude and frequency on the thermal dependence of magnetizations, magnetization reversal mechanisms during hysteresis cycles, as well as on the exchange bias and coercive fields have been examined, and the feasibility of applying dynamic magnetic fields on the particle have been discussed for technological and biomedical purposes.

  5. Thermal and mechanical properties of novel nanocomposites from modified ordered mesoporous carbon FDU-15 and poly(methyl methacrylate)

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadnezhad, Gholamhossein, E-mail: mohammadnezhad@cc.iut.ac.ir; Dinari, Mohammad, E-mail: dinari@cc.iut.ac.ir; Soltani, Roozbeh; Bozorgmehr, Zahra

    2015-08-15

    Graphical abstract: - Highlights: • The surface of mesoporous carbon, FDU-15, was modified by 3-mercaptopropyl-trimethoxysilane. • Nanocomposites of PMMA and modified FDU-15 were prepared by solution polymerization. • XRD shows that modified mesoporous FDU-15 has an ordered hexagonal mesostructure. • TEM and SEM images confirm the presence of large pores and ordered mesostructure. • Mechanical data indicated improvement in the tensile strength and modulus. - Abstract: With its well-ordered pore structure, high specific surface area and tunable pore diameters, ordered mesoporous carbons are suitable for applications in many areas of modern science and technology. In the present investigation, an ultrasonic irradiation was used for the modification of the mesoporous carbon FDU-15. Three nanocomposite films of the poly(methyl methacrylate) (PMMA) and modified FDU-15 were prepared by solution polymerization technique. The surface morphology and thermal and mechanical properties of the hybrid materials were evaluated by different methods. X-ray diffraction patterns showed that modified mesoporous FDU-15 had an ordered hexagonal mesostructure. Transmission electron microscopy (TEM) and field emission-scanning electron microscopy images confirmed the presence of large pores and a relatively ordered mesostructure for the functionalized materials. Thermogravimetric analysis data also revealed that the onset of decomposition temperature of the nanocomposites was higher than that of pristine PMMA, shifting toward higher temperatures as the amount of modified-FDU was increased. TEM images showed the well-ordered hexagonal arrays of mesopores FDU-15. Mechanical data indicated the improvement in the tensile strength and modulus with the modified FDU-15 loading. The film containing 1 wt.% of modified FDU-15 had a tensile strength of the order of 42 MPa, relative to the 28 MPa of the pristine PMMA.

  6. Introducing Catastrophe-QSAR. Application on Modeling Molecular Mechanisms of Pyridinone Derivative-Type HIV Non-Nucleoside Reverse Transcriptase Inhibitors

    Directory of Open Access Journals (Sweden)

    Marius Lazea

    2011-12-01

    Full Text Available The classical method of quantitative structure-activity relationships (QSAR is enriched using non-linear models, as Thom’s polynomials allow either uni- or bi-variate structural parameters. In this context, catastrophe QSAR algorithms are applied to the anti-HIV-1 activity of pyridinone derivatives. This requires calculation of the so-called relative statistical power and of its minimum principle in various QSAR models. A new index, known as a statistical relative power, is constructed as an Euclidian measure for the combined ratio of the Pearson correlation to algebraic correlation, with normalized t-Student and the Fisher tests. First and second order inter-model paths are considered for mono-variate catastrophes, whereas for bi-variate catastrophes the direct minimum path is provided, allowing the QSAR models to be tested for predictive purposes. At this stage, the max-to-min hierarchies of the tested models allow the interaction mechanism to be identified using structural parameter succession and the typical catastrophes involved. Minimized differences between these catastrophe models in the common structurally influential domains that span both the trial and tested compounds identify the “optimal molecular structural domains” and the molecules with the best output with respect to the modeled activity, which in this case is human immunodeficiency virus type 1 HIV-1 inhibition. The best molecules are characterized by hydrophobic interactions with the HIV-1 p66 subunit protein, and they concur with those identified in other 3D-QSAR analyses. Moreover, the importance of aromatic ring stacking interactions for increasing the binding affinity of the inhibitor-reverse transcriptase ligand-substrate complex is highlighted.

  7. Introducing Catastrophe-QSAR. Application on Modeling Molecular Mechanisms of Pyridinone Derivative-Type HIV Non-Nucleoside Reverse Transcriptase Inhibitors

    Science.gov (United States)

    Putz, Mihai V.; Lazea, Marius; Putz, Ana-Maria; Duda-Seiman, Corina

    2011-01-01

    The classical method of quantitative structure-activity relationships (QSAR) is enriched using non-linear models, as Thom’s polynomials allow either uni- or bi-variate structural parameters. In this context, catastrophe QSAR algorithms are applied to the anti-HIV-1 activity of pyridinone derivatives. This requires calculation of the so-called relative statistical power and of its minimum principle in various QSAR models. A new index, known as a statistical relative power, is constructed as an Euclidian measure for the combined ratio of the Pearson correlation to algebraic correlation, with normalized t-Student and the Fisher tests. First and second order inter-model paths are considered for mono-variate catastrophes, whereas for bi-variate catastrophes the direct minimum path is provided, allowing the QSAR models to be tested for predictive purposes. At this stage, the max-to-min hierarchies of the tested models allow the interaction mechanism to be identified using structural parameter succession and the typical catastrophes involved. Minimized differences between these catastrophe models in the common structurally influential domains that span both the trial and tested compounds identify the “optimal molecular structural domains” and the molecules with the best output with respect to the modeled activity, which in this case is human immunodeficiency virus type 1 HIV-1 inhibition. The best molecules are characterized by hydrophobic interactions with the HIV-1 p66 subunit protein, and they concur with those identified in other 3D-QSAR analyses. Moreover, the importance of aromatic ring stacking interactions for increasing the binding affinity of the inhibitor-reverse transcriptase ligand-substrate complex is highlighted. PMID:22272148

  8. Sequential Polarity-Reversing Circuit

    Science.gov (United States)

    Labaw, Clayton C.

    1994-01-01

    Proposed circuit reverses polarity of electric power supplied to bidirectional dc motor, reversible electro-mechanical actuator, or other device operating in direction depending on polarity. Circuit reverses polarity each time power turned on, without need for additional polarity-reversing or direction signals and circuitry to process them.

  9. Numerical Analysis of Forth-Order Boundary Value Problems in Fluid Mechanics and Mathematics

    DEFF Research Database (Denmark)

    Hosseinzadeh, E.; Barari, Amin; Fouladi, F.

    2011-01-01

    In this paper He's variational iteration method is used to solve some examples of linear and non-linear forth-order boundary value problems. The first problem compared with homotopy analysis method solution and the other ones with the exact solution. The results show the high accuracy and speed...

  10. Numerical analysis of fourth-order boundary value problems in fluid mechanics and mathematics

    DEFF Research Database (Denmark)

    Hosseinzadeh, Elham; Barari, Amin; Fouladi, Fama

    2010-01-01

    In this paper He's variational iteration method is used to solve some examples of linear and non-linear forth-order boundary value problems. The first problem compared with homotopy analysis method solution and the other ones with the exact solution. The results show the high accuracy and speed...

  11. Numerical Analysis of Forth-Order Boundary Value Problems in Fluid Mechanics and Mathematics

    DEFF Research Database (Denmark)

    Hosseinzadeh, E.; Barari, Amin; Fouladi, F.

    2011-01-01

    In this paper He's variational iteration method is used to solve some examples of linear and non-linear forth-order boundary value problems. The first problem compared with homotopy analysis method solution and the other ones with the exact solution. The results show the high accuracy and speed...

  12. High order Hamiltonian water wave models with wave-breaking mechanism

    NARCIS (Netherlands)

    Kurnia, R.; Groesen, van E.

    2014-01-01

    Based on the Hamiltonian formulation of water waves, using Hamiltonian consistent modelling methods, we derive higher order Hamiltonian equations by Taylor expansions of the potential and the vertical velocity around the still water level. The polynomial expansion in wave height is mixed with pseudo

  13. Reverse Logistics

    OpenAIRE

    Kulikova, Olga

    2016-01-01

    This thesis was focused on the analysis of the concept of reverse logistics and actual reverse processes which are implemented in mining industry and finding solutions for the optimization of reverse logistics in this sphere. The objective of this paper was the assessment of the development of reverse logistics in mining industry on the example of potash production. The theoretical part was based on reverse logistics and mining waste related literature and provided foundations for further...

  14. Order statistics inference for describing topological coupling and mechanical symmetry breaking in multidomain proteins

    CERN Document Server

    Kononova, Olga; Barsegov, Valeri

    2015-01-01

    Cooperativity is a hallmark of proteins, many of which show a modular architecture comprising discrete structural domains. Detecting and describing dynamic couplings between structural regions is difficult in view of the many-body nature of protein-protein interactions. By utilizing the GPU-based computational acceleration, we carried out simulations of the protein forced unfolding for the dimer WW-WW of the all-beta-sheet WW domains used as a model multidomain protein. We found that while the physically non-interacting identical protein domains (WW) show nearly symmetric mechanical properties at low tension, reflected, e.g., in the similarity of their distributions of unfolding times, these properties become distinctly different when tension is increased. Moreover, the uncorrelated unfolding transitions at a low pulling force become increasingly more correlated (dependent) at higher forces. Hence, the applied force not only breaks "the mechanical symmetry" but also couples the physically non-interacting prot...

  15. When do doctors follow patients' orders? Organizational mechanisms of physician influence.

    Science.gov (United States)

    Menchik, Daniel A; Jin, Lei

    2014-11-01

    Physicians, like other professionals, are expected to draw from specialized knowledge while remaining receptive to clients' requests. Using nationally representative U.S. survey data from the Community Tracking Study, this paper examines the degree to which physicians are influenced by patients' requests, and how physicians' workplaces may mediate acquiescence rates through three mechanisms: constraints, protection, and incentives. We find that, based on physicians' reports of their responses to patients' suggestions, patient influence is rare. This influence is least likely to be felt in large workplaces, such as large private practices, hospitals, and medical schools. We find that the protection and incentives mechanisms mediate the relationship between workplace types and physician acquiescence but more prescriptive measures such as guidelines and formularies do not affect acquiescence. We discuss these findings in light of the ongoing changes in the structure of medicine. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Formulation and validation of high-order linearized models of helicopter flight mechanics

    Science.gov (United States)

    Kim, Frederick D.; Celi, Roberto; Tischler, Mark B.

    1990-01-01

    A high-order linearized model of helicopter flight dynamics is extracted from a nonlinear time domain simulation. The model has 29 states that describe the fuselage rigid body degrees of freedom, the flap and lag dynamics in a nonrotating coordinate system, the inflow dynamics, the delayed entry of the horizontal tail into the main rotor wake, and, approximately, the blade torsion dynamics. The nonlinear simulation is obtained by extensively modifying the GENHEL computer program. The results indicate that the agreement between the linearized and the nonlinear model is good for small perturbations, and deteriorates for large amplitude maneuvers.

  17. Effect of long-period stacking ordered phase on microstructure, mechanical property and corrosion resistance of Mg alloys: A review

    Directory of Open Access Journals (Sweden)

    Daokui Xu

    2016-04-01

    Full Text Available Magnesium alloys containing long period stacking ordered (LPSO phase have been received a great deal of attention in the last decade owing to their excellent comprehensive properties of mechanical strength and corrosion resistance. In this paper, some fundamental aspects of LPSO containing Mg alloys have been reviewed, including: (1 microstructural characterization, formation conditions and the associated phase transformation of LPSO phases in Mg alloys; (2 deformation mechanism of LPSO phases and their influence on the deformation mechanism of the Mg matrix; (3 effect of LPSO structure on the mechanical performance such as tensile strength, creep resistance, fracture toughness and fatigue strength; (4 corrosion behavior of LPSO containing Mg alloys and their possible applications as the biomaterials. Moreover, some remaining unsolved issues of the LPSO containing Mg alloys and the future target about how to further improve their service properties have been also described.

  18. Rapid and reversible impairments of short- and long-term social recognition memory are caused by acute isolation of adult rats via distinct mechanisms.

    Science.gov (United States)

    Shahar-Gold, Hadar; Gur, Rotem; Wagner, Shlomo

    2013-01-01

    Mammalian social organizations require the ability to recognize and remember individual conspecifics. This social recognition memory (SRM) can be examined in rodents using their innate tendency to investigate novel conspecifics more persistently than familiar ones. Here we used the SRM paradigm to examine the influence of housing conditions on the social memory of adult rats. We found that acute social isolation caused within few days a significant impairment in acquisition of short-term SRM of male and female rats. Moreover, SRM consolidation into long-term memory was blocked following only one day of social isolation. Both impairments were reversible, but with different time courses. Furthermore, only the impairment in SRM consolidation was reversed by systemic administration of arginine-vasopressin (AVP). In contrast to SRM, object recognition memory was not affected by social isolation. We conclude that acute social isolation rapidly induces reversible changes in the brain neuronal and molecular mechanisms underlying SRM, which hamper its acquisition and completely block its consolidation. These changes occur via distinct, AVP sensitive and insensitive mechanisms. Thus, acute social isolation of rats swiftly causes changes in their brain and interferes with their normal social behavior.

  19. Resurgence structure to all orders of multi-bions in deformed SUSY quantum mechanics

    Science.gov (United States)

    Fujimori, Toshiaki; Kamata, Syo; Misumi, Tatsuhiro; Nitta, Muneto; Sakai, Norisuke

    2017-08-01

    We investigate the resurgence structure in quantum mechanical models originating in 2d nonlinear sigma models with emphasis on nearly supersymmetric and quasi-exactly solvable parameter regimes. By expanding the ground state energy in powers of a supersymmetry-breaking deformation parameter δ ɛ, we derive exact results for the expansion coefficients. In the class of models described by real multiplets, the O(δɛ) ground state energy has a non-Borel summable asymptotic series, which gives rise to imaginary ambiguities leading to rich resurgence structure. We discuss sine-Gordon quantum mechanics (QM) as an example and show that the semiclassical contributions from complex multi-bion solutions correctly reproduce the corresponding part in the exact result including the imaginary ambiguities. As a typical model described by chiral multiplets, we discuss CP^{N-1} QM and show that the exact O(δɛ) ground state energy can be completely reconstructed from the semiclassical multi-bion contributions. Although the O(δɛ) ground state energy has trivial resurgence structure, a simple but rich resurgence structure appears at O(δɛ2). We show the complete cancelation between the O(δɛ2) imaginary ambiguities arising from the non-Borel summable perturbation series and those in the semiclassical contributions of N-1 complex bion solutions. We also discuss the resurgence structure of a squashed {C}P^1 QM.

  20. A Reduced Order Model of Force Displacement Curves for the Failure of Mechanical Bolts in Tension.

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Keegan J. [Univ. of Illinois, Urbana-Champaign, IL (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brake, Matthew Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-12-01

    Assembled mechanical systems often contain a large number of bolted connections. These bolted connections (joints) are integral aspects of the load path for structural dynamics, and, consequently, are paramount for calculating a structure's stiffness and energy dissipation prop- erties. However, analysts have not found the optimal method to model appropriately these bolted joints. The complexity of the screw geometry causes issues when generating a mesh of the model. This report will explore different approaches to model a screw-substrate connec- tion. Model parameters such as mesh continuity, node alignment, wedge angles, and thread to body element size ratios are examined. The results of this study will give analysts a better understanding of the influences of these parameters and will aide in finding the optimal method to model bolted connections.

  1. Europium Structural Effect on a Borosilicate Glass of Nuclear Interest: Combining Experimental Techniques with Reverse Monte Carlo Modelling to Investigate Short to Medium Range Order

    Science.gov (United States)

    Bouty, O.; Delaye, J. M.; Peuget, S.; Charpentier, T.

    In-depth understanding of the effects of actinides in borosilicate glass matrices used for nuclear waste disposal is of great importance for nuclear spent fuel reprocessing cycle and fission products immobilization. This work carried out on ternary simplified glasses (Si, B, Na) doped respectively with 1 mol. % and 3.85 mol. % europium, presents a comprehensive study on the behaviour of trivalent europium taken as a surrogate of trivalent actinides. Neutron scattering, Wide Angle X- ray Scattering, Nuclear Magnetic Resonance, Raman Spectroscopy and Reverse Monte Carlo simulations were performed. For both glasses, it was found that europium coordination number was around 6 ± 0.2, revealing an octahedral spatial configuration. Europium species accommodates in both silicate and borate site distributions but preferentially in the silicate network. Europium induces a IVB/IIIB ratio decrease and a silicate network polymerization according to NMR 29Si chemical shift and Raman spectra evolution.

  2. Molecular mechanism of indirubin-3'-monoxime and Matrine in the reversal of paclitaxel resistance in NCI-H520/TAX25 cell line

    Institute of Scientific and Technical Information of China (English)

    LUO Su-xia; DENG Wen-ying; WANG Xin-feng; L(U) Hui-fang; HAN Li-li; CHEN Bei-bei; CHEN Xiao-bing

    2013-01-01

    Background Multidrug resistance (MDR) is a main reason for paclitaxel (TAX) treatment failure.Indirubin-3'-monoxime (IRO) and Matrine are traditional Chinese medicines,which may reverse the resistance of tumor cells to some chemotherapy drugs,but the relationship between paclitaxel resistance and Matrine is still unclear.The aim of this study was to explore the potential molecular mechanism of IRO and Matrine in reversal of TAX resistance.Methods In this study,MTT assay was used to measure the non-cytotoxic dosage of IRO and Matrine on NCI-H520/TAX25 cells and determine the reversal extent of TAX resistance under non-toxic doses.In addition,RT-PCR and Western blotting were used to evaluate the mRNA expression and the protein level of survivin,Oct-4,and Sox-2 in NCI-H520/FAX25 cells using semi-quantitative methods.Results There was no obvious inhibition on sensitive cell strains and drug-resistant strains,when the final concentration was at lest 4 μmol/L for IRO and 100 μmol/L for Matrine.So 4 μmol/L of IRO and 100 μmol/L of Matrine were considered as the reversal dosage.When 4 μmol/L of IRO or 100 μmol/L of Matrine were used together with TAX,the sensitivity to TAX increased evidently in NCI-H520/TAX2 cells; the reversal rate of IRO and Matrine was about 1.92 (43.56/22.6 nmol/L) and 1.74 (43.56/25.0 nmol/L),respectively.The mRNA expression and the protein level of survivin,Oct-4,and Sox-2 in NCI-H520/TAX25 decreased significantly (P <0.05) after addition of IRO or Matrine in TAX treatment,compared to that of TAX treatment alone.Conclusion The decrease in both mRNA expression and protein level of survivin,Oct-4,and Sox-2 might be the molecular mechanism,by which IRO and Matrine mediate the reversal of TAX resistance.

  3. First-order Description of the Mechanical Fracture Behavior of Fine-Grained Surficial Marine Sediments During Gas Bubble Growth

    Science.gov (United States)

    2010-01-01

    10 F04O29 BARRY ET AL.: BUBBLE GROWTH BY FRACTURE P04029 Figure 3. Map of field site. Canard, Nova Scotia, Canada. appears to approximate the...Bottinger. and T. Dahm (2005), Buoyancy-driven fracture ascent: Experiments in layered gelatine. J. Volcano!. Geotherm . Res., 144. 273-285. doi...Journal Article 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE First-order description of the mechanical fracture behavior of fine-grained

  4. High-Order Two-Dimension Cluster Competitive Activation Mechanisms Used for Performing Symbolic Logic Algorithms of Problem Solving

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    This paper presents a neural network approach,based on high-order twodimension temporal and dynamically clustering competitive activation mechanisms,to implement parallel searching algorithm and many other symbolic logic algorithms.This approach is superior in many respects to both the common sequential algorithms of symbolic logic and the common neural network used for optimization problems.Simulations of problem solving examples prove the effectiveness of the approach.

  5. Task order #24 update: exploration of damage mechanisms in cylindrical geometry

    Energy Technology Data Exchange (ETDEWEB)

    Kaul, Ann M [Los Alamos National Laboratory

    2011-01-14

    A typical method of failure for ductile materials is spallation damage, which is caused by the nucleation, growth and coalescence of voids due to the presence of high tensile stress in the material. Spallation damage models, such as TEPLA, are currently implemented in hydrodynamic computer codes used at Los Alamos National Laboratory (LANL). Parameters for such constitutive models are derived from data sets obtained primarily from gas gun and shock-driven experiments, which are designed to allow one-dimensional analysis of the evolution of the failure characteristics. However, in a non-planar geometry, advanced failure models predict failure to be a multi-dimensional process. Additionally, a limited amount of data exists for the process of void nucleation, growth and coalescence. Another lightly researched area is the state of the material in the event that the spallation layer is recollected and voids are closed. The experiments described here are being conducted as part of a Campaign-l effort to provide data addressing these issues. The Russian Damage Experimental Series is designed to provide fundamental non-planar (cylindrical) spallation damage data, including early time processes (void nucleation, growth and coalescence) and late time processes (recollection of the spallation layer). Previous experiments produced data addressing some of the early time processes. This presentation will be provided to LANL and VNIIEF colleagues as a means of assessing the status of Task Order No.24 at the current time.

  6. A simple higher order shear deformation theory for mechanical behavior of laminated composite plates

    Science.gov (United States)

    Adim, Belkacem; Daouadji, Tahar Hassaine; Rabahi, Aberezak

    2016-06-01

    In the present study, the static, buckling, and free vibration of laminated composite plates is examined using a refined shear deformation theory and developed for a bending analysis of orthotropic laminated composite plates. These models take into account the parabolic distribution of transverse shear stresses and satisfy the condition of zero shear stresses on the top and bottom surfaces of the plates. The most interesting feature of this theory is that it allows for parabolic distributions of transverse shear stresses across the plate thickness and satisfies the conditions of zero shear stresses at the top and bottom surfaces of the plate without using shear correction factors. The number of independent unknowns in the present theory is four, as against five in other shear deformation theories. In the analysis, the equation of motion for simply supported thick laminated rectangular plates is obtained through the use of Hamilton's principle. The accuracy of the analysis presented is demonstrated by comparing the results with solutions derived from other higher order models and with data found in the literature. It can be concluded that the proposed theory is accurate and simple in solving the static, the buckling, and free vibration behaviors of laminated composite plates.

  7. Evidence of ferrimagnetic ordering in FeMnO{sub 3} produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Seifu, D. E-mail: dseifu@morgan.edu; Kebede, A.; Oliver, F.W.; Hoffman, E.; Hammond, E.; Wynter, C.; Aning, A.; Takacs, L.; Siu, I.-L.; Walker, J.C.; Tessema, G.; Seehra, M.S

    2000-03-01

    Mechanical alloying of {alpha}-Fe{sub 2}O{sub 3} with Mn{sub 2}O{sub 3} is shown to produce FeMnO{sub 3}, whose X-ray diffraction pattern fits the cubic structure (space group Ia3, lattice constant {approx}9.40 A) identical to that of Mn{sub 2}O{sub 3}. Temperature variation of its magnetic susceptibility {chi} shows a phase transition near T{sub c}{approx}40 K and the {chi}{sup -1} versus T data for T>T{sub c} fit the variation expected for a ferrimagnet with a magnetic moment of 2.8 {mu}{sub B} per formula unit. The Moessbauer spectrum for T>T{sub c} is a doublet with quadrupole splitting {approx}1 mm/s and isomer shift {approx}0.4 mm/s, changing to a sextet for T

  8. The Hydraulic Mechanism of the Unfolding of Hind Wings in Dorcus titanus platymelus (Order: Coleoptera

    Directory of Open Access Journals (Sweden)

    Jiyu Sun

    2014-04-01

    Full Text Available In most beetles, the hind wings are thin and fragile; when at rest, they are held over the back of the beetle. When the hind wing unfolds, it provides the necessary aerodynamic forces for flight. In this paper, we investigate the hydraulic mechanism of the unfolding process of the hind wings in Dorcus titanus platymelus (Oder: Coleoptera. The wing unfolding process of Dorcus titanus platymelus was examined using high speed camera sequences (400 frames/s, and the hydraulic pressure in the veins was measured with a biological pressure sensor and dynamic signal acquisition and analysis (DSA during the expansion process. We found that the total time for the release of hydraulic pressure during wing folding is longer than the time required for unfolding. The pressure is proportional to the length of the wings and the body mass of the beetle. A retinal camera was used to investigate the fluid direction. We found that the peak pressures correspond to two main cross-folding joint expansions in the hind wing. These observations strongly suggest that blood pressure facilitates the extension of hind wings during unfolding.

  9. Optimal Ordering Policy and Coordination Mechanism of a Supply Chain with Controllable Lead-Time-Dependent Demand Forecast

    Directory of Open Access Journals (Sweden)

    Hua-Ming Song

    2011-01-01

    Full Text Available This paper investigates the ordering decisions and coordination mechanism for a distributed short-life-cycle supply chain. The objective is to maximize the whole supply chain's expected profit and meanwhile make the supply chain participants achieve a Pareto improvement. We treat lead time as a controllable variable, thus the demand forecast is dependent on lead time: the shorter lead time, the better forecast. Moreover, optimal decision-making models for lead time and order quantity are formulated and compared in the decentralized and centralized cases. Besides, a three-parameter contract is proposed to coordinate the supply chain and alleviate the double margin in the decentralized scenario. In addition, based on the analysis of the models, we develop an algorithmic procedure to find the optimal ordering decisions. Finally, a numerical example is also presented to illustrate the results.

  10. Higher-order rational solitons and rogue-like wave solutions of the (2 + 1)-dimensional nonlinear fluid mechanics equations

    Science.gov (United States)

    Wen, Xiao-Yong; Yan, Zhenya

    2017-02-01

    The novel generalized perturbation (n, M)-fold Darboux transformations (DTs) are reported for the (2 + 1)-dimensional Kadomtsev-Petviashvili (KP) equation and its extension by using the Taylor expansion of the Darboux matrix. The generalized perturbation (1 , N - 1) -fold DTs are used to find their higher-order rational solitons and rogue wave solutions in terms of determinants. The dynamics behaviors of these rogue waves are discussed in detail for different parameters and time, which display the interesting RW and soliton structures including the triangle, pentagon, heptagon profiles, etc. Moreover, we find that a new phenomenon that the parameter (a) can control the wave structures of the KP equation from the higher-order rogue waves (a ≠ 0) into higher-order rational solitons (a = 0) in (x, t)-space with y = const . These results may predict the corresponding dynamical phenomena in the models of fluid mechanics and other physically relevant systems.

  11. Measuring the spatial frequency selectivity of second-order texture mechanisms.

    Science.gov (United States)

    Sutter, A; Sperling, G; Chubb, C

    1995-04-01

    Recent investigations of texture and motion perception suggest two early filtering stages: an initial stage of selective linear filtering followed by rectification and a second stage of linear filtering. Here we demonstrate that there are differently scaled second-stage filters, and we measure their contrast modulation sensitivity as a function of spatial frequency. Our stimuli are Gabor modulations of a suprathreshold, bandlimited, isotropic carrier noise. The subjects' task is to discriminate between two possible orientations of the Gabor. Carrier noises are filtered into four octave-wide bands, centered at m = 2, 4, 8, and 16 c/deg. The Gabor test signals are w = 0.5, 1, 2, 4 and 8 c/deg. The threshold modulation of the test signal is measured for all 20 combinations of m and w. For each carrier frequency m, the Gabor test frequency w to which subjects are maximally sensitive appears to be approximately 3-4 octaves below m. The consistent m x w interaction suggests that each second-stage spatial filter may be differentially tuned to a particular first-stage spatial frequency. The most sensitive combination is a second-stage filter of 1 c/deg with first-stage inputs of 8-16 c/deg. We conclude that second-order texture perception appears to utilize multiple channels tuned to spatial frequency and orientation, with channels tuned to low modulation frequencies appearing to be best served by carrier frequencies 8 to 16 times higher than the modulations they are tuned to detect.

  12. Psychological Mechanism Underlying Preference Reversals in Intertemporal Choice%跨期选择中偏好反转的心理机制

    Institute of Scientific and Technical Information of China (English)

    陈海贤; 何贵兵

    2012-01-01

    通过直接测量近期和远期选择中备选项激活的情绪、间隔的时间知觉及对备选项金额差异和时间间隔的重视程度,以探究跨期选择中偏好反转产生的心理机制。结果表明:(1)近期选择中,备选项激活的情绪强度差异显著,而远期选择中两者的差异不显著;(2)近期和远期选择中,情绪强度差异和时间知觉差异能够预测偏好反转的发生。研究结果支持了偏好反转的情绪激活差异假说和时间知觉差异假说。%Preference reversals in intertemporal choice refer to the tendency of a decision maker to prefer alternative SS(Sooner-Smaller) to LL(Larger-Later) when the outcomes are near but prefer alternative LL to SS when the outcomes are distant.Preference reversals cast doubts on the DU(Discounting Utility) model,which assumed stationary preferences across time. There are three main theories about psychological mechanism underlying preference reversals.The first theory hypothesized that choices between the immediate outcome and the distant outcome activated stronger impulsive affection than choices between distant outcomes. Different impulsive affection caused reversals(Loewenstein,1996;Metcalfe Mischel,1999).The second theory hypothesized that the subject interval perception was longer in near choices than in distant choices,even though the object interval between alternatives was the same(Takahashi,Oonob, Radfordb,2008;Zauberman,Kim,Malkoc, Bettman,2009).Different interval perception caused different value discounting,which caused reversals.The third theory hypothesized that the magnitude of money (high-level construal) were more weighted whereas interval(low-level construal) was less weighted as psychology distance increased, and the varing weight of money and interval in near and distant choices caused reversals(Trope Liberman,2003,2010). The purpose of this study was to test these theories.We hypothesized that the psychological variables underlying

  13. Collecting Variable-concentration Isothermal Titration Calorimetry Datasets in Order to Determine Binding Mechanisms

    Science.gov (United States)

    Freiburger, Lee A.; Mittermaier, Anthony K.; Auclair, Karine

    2011-01-01

    the two subunits. However ITC data obtained at a single c-value can be fit equally well to at least two different models a two-sets-of-sites independent model and a two-site sequential (cooperative) model. Through varying the c-value as explained above, it was established that the correct binding model for AAC(6')-Ii is a two-site sequential binding model. Herein, we describe the steps that must be taken when performing ITC experiments in order to obtain datasets suitable for variable-c analyses. PMID:21505408

  14. Collecting variable-concentration isothermal titration calorimetry datasets in order to determine binding mechanisms.

    Science.gov (United States)

    Freiburger, Lee A; Mittermaier, Anthony K; Auclair, Karine

    2011-04-07

    the two subunits. However ITC data obtained at a single c-value can be fit equally well to at least two different models a two-sets-of-sites independent model and a two-site sequential (cooperative) model. Through varying the c-value as explained above, it was established that the correct binding model for AAC(6')-Ii is a two-site sequential binding model. Herein, we describe the steps that must be taken when performing ITC experiments in order to obtain datasets suitable for variable-c analyses.

  15. Revealing mechanism responsible for structural reversibility of single-crystal VO2 nanorods upon lithiation/delithiation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qi; Tan, Guoqiang; Wang, Peng; Abeyweera, Sasitha C.; Zhang, Dongtang; Rong, Yangchun; Wu, Yimin; Lu, Jun; Sun, Cheng-Jun; Ren, Yang; Liu, Yuzi; Muehleisen, Ralph T.; Guzowski, Leah B.; Li, Jie; Xiao, Xianghui; Sun, Yugang

    2017-04-17

    A pure phase of VO2(B) nanorods have been synthesized through an energy-efficient microwave hydrothermal reaction and used as cathode materials of lithium ion batteries, which exhibit promising specific capacity (e.g., 130 mA h g-1 even after 100 charge/discharge cycles) and rate capacity (e.g., ~130 mA h g-1 at a high current of 400 mA g-1). The excellent cyclability originates from the structural reversibility of VO2(B) upon lithiation/delithiation that is confirmed by the in situ high-energy synchrotron X-ray diffraction (HEXRD) and in situ x-ray adsorption near-edge spectroscopy (XANES) of the VO2 nanorods in operating battery cells. As a result, the real-time results reveal that discharge forces lithium ions to insert firstly into the tunnels with the largest size along b direction followed by the second largest tunnels along c direction, which is completely reversible in the charge process.

  16. Chemical ordering in Pd$_{81}$Ge$_{19}$ metallic glass studied by reverse Monte-Carlo modelling of XRD, ND and EXAFS experimental data

    CERN Document Server

    Pethes, Ildikó; Stoica, Mihai; Beuneu, Brigitte; Jóvári, Pál

    2016-01-01

    Pd$_{81}$Ge$_{19}$ metallic glass was investigated by neutron diffraction, X-ray diffraction and extended X-ray absorption fine structure spectroscopy (EXAFS) at the Ge K-edge. Large scale structural models were obtained by fitting the three measurements simultaneously in the framework of the reverse Monte Carlo simulation technique. It was found that the experimental data sets can be adequately fitted without Ge-Ge nearest neighbours. Mean Pd-Pd and Pd-Ge distances are 2.80$\\pm$0.02 {\\AA} and 2.50$\\pm$0.02 {\\AA}, respectively. The total average coordination number of Pd is 12.1$\\pm$0.5 while Ge is surrounded by 10.6$\\pm$1.1 Pd atoms. The coordination numbers calculated from partial pair correlation functions were compared to those obtained by Voronoi tessellation method. It was found that the latter technique overestimates the number of nearest neighbours by about 20% due to the significant contribution of distant pairs.

  17. Chemical ordering in Pd81Ge19 metallic glass studied by reverse Monte-Carlo modelling of XRD, ND and EXAFS experimental data

    Science.gov (United States)

    Pethes, Ildikó; Kaban, Ivan; Stoica, Mihai; Beuneu, Brigitte; Jóvári, Pál

    2016-10-01

    Pd81Ge19 metallic glass was investigated by neutron diffraction, x-ray diffraction and extended x-ray absorption fine structure spectroscopy at the Ge K-edge. Large scale structural models were obtained by fitting the three measurements simultaneously in the framework of the reverse Monte Carlo simulation technique. It was found that the experimental data sets can be adequately fitted without Ge-Ge nearest neighbours. Mean Pd-Pd and Pd-Ge distances are 2.80 ± 0.02 Å and 2.50 ± 0.02 Å, respectively. The total average coordination number of Pd is 12.1 ± 0.5 while Ge is surrounded by 10.6 ± 1.1 Pd atoms. The coordination numbers calculated from partial pair correlation functions were compared to those obtained by Voronoi tessellation method. It was found that the latter technique overestimates the number of nearest neighbours by about 20% due to the significant contribution of distant pairs.

  18. Experimental and theoretical confirmation of the role of higher order mechanisms in the electron impact double ionization of helium

    Energy Technology Data Exchange (ETDEWEB)

    Casagrande, E M Staicu; Li, C; Lahmam-Bennani, A [Institut des Sciences Moleculaires d' Orsay (ISMO, UMR 8214), Universite Paris-Sud 11, Bat. 351, 91405 Orsay Cedex (France); Cappello, C Dal [Institut de Physique, Universite Paul Verlaine-Metz, Laboratoire de Physique Moleculaire et des Collisions, ICPMB (FR 2843), 1 rue Arago, 57078 Metz Cedex 3 (France); Schulz, M [Department of Physics and LAMOR, Missouri University of Science and Technology, Rolla, MO 65409 (United States); Ciappina, M, E-mail: azzedine.bennani@u-psud.fr [Institute of High Performance Computing, 1 Fusionopolis Way, 16-16 Connexis, 138632 Singapore (Singapore)

    2011-03-14

    Our recent measurements (Lahmam-Bennani et al 2010 J. Phys. B: At. Mol. Opt. Phys. 43 105201) of the (e,3-1e) four-fold differential cross sections (4DCS) for double ionization (DI) of helium are extended here to a wider range of ejected electron energies and very asymmetric energy sharing. Previous observations of large angular shifts in the experimental 4DCS distributions with respect to the momentum transfer axis are once again reproduced by the new measured data. Moreover, a comparison of all the data sets with the kinematical analysis previously given and with two newly developed non-first-order theoretical models for DI-namely the two-step 2-Monte Carlo event generator (TS2-MCEG) and a second Born approximation (B2)-confirms our interpretation which allows the observed shifts and the existence of structures in the intensity distributions to be mostly related to the second order, TS2 DI mechanism, which is shown to predominate over the first-order 'shake-off' (SO) and 'two-step 1' (TS1) mechanisms under the present kinematics.

  19. Novel high-throughput screen identifies an HIV-1 reverse transcriptase inhibitor with a unique mechanism of action.

    Science.gov (United States)

    Sheen, Chih-Wei; Alptürk, Onur; Sluis-Cremer, Nicolas

    2014-09-15

    HIV-1 resistance to zidovudine [AZT (azidothymidine)] is associated with selection of the mutations M41L, D67N, K70R, L210W, T215F/Y and K219Q/E in RT (reverse transcriptase). These mutations decrease HIV-1 susceptibility to AZT by augmenting RT's ability to excise the chain-terminating AZT-MP (AZT-monophosphate) moiety from the chain-terminated DNA primer. Although AZT-MP excision occurs at the enzyme's polymerase active site, it is mechanistically distinct from the DNA polymerase reaction. Consequently, this activity represents a novel target for drug discovery, and inhibitors that target this activity may increase the efficacy of nucleoside/nucleotide analogues, and may help to delay the onset of drug resistance. In the present study, we have developed a FRET (Förster resonance energy transfer)-based high-throughput screening assay for the AZT-MP excision activity of RT. This assay is sensitive and robust, and demonstrates a signal-to-noise ratio of 3.3 and a Z' factor of 0.69. We screened three chemical libraries (7265 compounds) using this assay, and identified APEX57219 {3,3'-[(3-carboxy-4-oxo-2,5-cyclohexadien-1-ylidene)methylene]bis[6-hydroxybenzoic acid]} as the most promising hit. APEX57219 displays a unique activity profile against wild-type and drug-resistant HIV-1 RT, and was found to inhibit virus replication at the level of reverse transcription. Mechanistic analyses revealed that APEX57219 blocked the interaction between RT and the nucleic acid substrate.

  20. Kinetic mechanism and order of substrate binding for sn-glycerol-3-phosphate acyltransferase from squash (Cucurbita moschata).

    Science.gov (United States)

    Hayman, Matthew W; Fawcett, Tony; Slabas, Antoni R

    2002-03-13

    sn-Glycerol-3-phosphate acyltransferase (G3PAT, EC 2.3.1.15), a component of glycerolipid biosynthesis, is an important enzyme in chilling sensitivity in plants. The three-dimensional structure of the enzyme from squash (Cucurbita moschata), without bound substrate, has been determined [Turnbull et al. (2001) Acta Crystallogr. D 57, 451-453; Turnbull et al. (2001) Structure 9, 347-353]. Here we report the kinetic mechanism of plastidial G3PAT from squash and the order of substrate binding using acyl-acyl carrier protein (acyl-ACP) substrates. The reaction proceeds via a compulsory-ordered ternary complex with acyl-ACP binding before glycerol-3-phosphate. We have also determined that the reaction will proceed with C(4:0)-CoA, C(6:0)-CoA and C(12:0)-ACP substrates, allowing a wider choice of acyl groups for future co-crystallisation studies.

  1. Exact second order formalism for the study of electro-acoustic properties in piezoelectric structures under an initial mechanical stress.

    Science.gov (United States)

    Lematre, M; Domenjoud, M; Tran-Huu-Hue, L P

    2011-12-01

    In this study we develop the exact second order formalism of piezoelectric structures under an external mechanical stress. Indeed, previous models are approximated since they consist in deriving all the equations in the natural coordinate system (corresponding to the pre-stress free case). Hence, our exact formalism proposes to obtain the whole of equations in the current coordinate system (which is the coordinate system after the pre-deformation). Then, this exact formalism is used to derive the modified Christoffel equations and the modified KLM model. Finally, we quantify the correction with the approximate formalism on several transfer functions and electro-mechanical parameters for a non hysteretic material (lithium niobate). In conclusion, we show that for this material, significant corrections are obtained when studying the plane wave velocities and the electrical input impedance (about 4%), whereas other parameters such as coupling coefficient and impulse response are less influenced by the choice of coordinate systems (corrections less than 0.5%).

  2. Why does shear banding behave like first-order phase transitions? Derivation of a potential from a mechanical constitutive model.

    Science.gov (United States)

    Sato, K; Yuan, X-F; Kawakatsu, T

    2010-02-01

    Numerous numerical and experimental evidence suggest that shear banding behavior looks like first-order phase transitions. In this paper, we demonstrate that this correspondence is actually established in the so-called non-local diffusive Johnson-Segalman model (the DJS model), a typical mechanical constitutive model that has been widely used for describing shear banding phenomena. In the neighborhood of the critical point, we apply the reduction procedure based on the center manifold theory to the governing equations of the DJS model. As a result, we obtain a time evolution equation of the flow field that is equivalent to the time-dependent Ginzburg-Landau (TDGL) equations for modeling thermodynamic first-order phase transitions. This result, for the first time, provides a mathematical proof that there is an analogy between the mechanical instability and thermodynamic phase transition at least in the vicinity of the critical point of the shear banding of DJS model. Within this framework, we can clearly distinguish the metastable branch in the stress-strain rate curve around the shear banding region from the globally stable branch. A simple extension of this analysis to a class of more general constitutive models is also discussed. Numerical simulations for the original DJS model and the reduced TDGL equation is performed to confirm the range of validity of our reduction theory.

  3. Towards Reversible Sessions

    Directory of Open Access Journals (Sweden)

    Francesco Tiezzi

    2014-06-01

    Full Text Available In this work, we incorporate reversibility into structured communication-based programming, to allow parties of a session to automatically undo, in a rollback fashion, the effect of previously executed interactions. This permits taking different computation paths along the same session, as well as reverting the whole session and starting a new one. Our aim is to define a theoretical basis for examining the interplay in concurrent systems between reversible computation and session-based interaction. We thus enrich a session-based variant of pi-calculus with memory devices, dedicated to keep track of the computation history of sessions in order to reverse it. We discuss our initial investigation concerning the definition of a session type discipline for the proposed reversible calculus, and its practical advantages for static verification of safe composition in communication-centric distributed software performing reversible computations.

  4. Calculated Third Order Rate Constants for Interpreting the Mechanisms of Hydrolyses of Chloroformates, Carboxylic Acid Halides, Sulfonyl Chlorides and Phosphorochloridates

    Directory of Open Access Journals (Sweden)

    T. William Bentley

    2015-05-01

    Full Text Available Hydrolyses of acid derivatives (e.g., carboxylic acid chlorides and fluorides, fluoro- and chloroformates, sulfonyl chlorides, phosphorochloridates, anhydrides exhibit pseudo-first order kinetics. Reaction mechanisms vary from those involving a cationic intermediate (SN1 to concerted SN2 processes, and further to third order reactions, in which one solvent molecule acts as the attacking nucleophile and a second molecule acts as a general base catalyst. A unified framework is discussed, in which there are two reaction channels—an SN1-SN2 spectrum and an SN2-SN3 spectrum. Third order rate constants (k3 are calculated for solvolytic reactions in a wide range of compositions of acetone-water mixtures, and are shown to be either approximately constant or correlated with the Grunwald-Winstein Y parameter. These data and kinetic solvent isotope effects, provide the experimental evidence for the SN2-SN3 spectrum (e.g., for chloro- and fluoroformates, chloroacetyl chloride, p-nitrobenzoyl p-toluenesulfonate, sulfonyl chlorides. Deviations from linearity lead to U- or V-shaped plots, which assist in the identification of the point at which the reaction channel changes from SN2-SN3 to SN1-SN2 (e.g., for benzoyl chloride.

  5. Simultaneous removal of atrazine and copper using polyacrylic acid-functionalized magnetic ordered mesoporous carbon from water: adsorption mechanism

    Science.gov (United States)

    Zhou, Yaoyu; Zhang, Fengfeng; Tang, Lin; Zhang, Jiachao; Zeng, Guangming; Luo, Lin; Liu, Yuanyuan; Wang, Pei; Peng, Bo; Liu, Xiaocheng

    2017-03-01

    Highly efficient simultaneous removal of atrazine and Cu(II) was accomplished using synthesized polyacrylic acid-functionalized magnetic ordered mesoporous carbon (P-MMC) as compared to magnetic ordered mesoporous carbon (MMC) and ordered mesoporous carbon (OMC). The mutual effects and interactive mechanism of their adsorption onto P-MMC were investigated systematically by binary, preloading and thermodynamic adsorption procedures. In both binary and preloading systems, the adsorption of atrazine was inhibited to some extent by the presence of Cu(II) because of selective recognition and direct competition, but the presence of atrazine had negligible effect on Cu(II) desorption. With the coexistence of humic acid (0-20 mg L-1), both atrazine and Cu(II) sorption increased slightly in sole and binary systems. With the concentration of coexisting NaCl increasing from 0 to 100 mM, the adsorption capacity for Cu(II) slightly decreased, but as for atrazine adsorption, it decreased at first, and then increased slightly in sole and binary systems. P-MMC was applied to treat real environmental samples, and the sorption capacities for atrazine and Cu(II) in real samples were all more than 91.47% and 96.43% of those in lab ultrapure water, respectively. Finally, comprehensively considering the relatively good renewability and the superior behavior in the application to real water samples, P-MMC has potential in removal of atrazine, Cu(II) and possibly other persistent organic pollutants from wastewater.

  6. Reverse logistics

    NARCIS (Netherlands)

    M.P. de Brito (Marisa); S.D.P. Flapper; R. Dekker (Rommert)

    2002-01-01

    textabstractThis paper gives an overview of scientific literature that describes and discusses cases of reverse logistics activities in practice. Over sixty case studies are considered. Based on these studies we are able to indicate critical factors for the practice of reverse logistics. In addi

  7. Mechanisms leading to sustained reversion of beta-thalassemia in mice by doxycycline-controlled Epo delivery from muscles.

    Science.gov (United States)

    Samakoglu, Selda; Bohl, Delphine; Heard, Jean Michel

    2002-12-01

    Erythropoiesis has been considered as a potential treatment for beta-thalassemia. Although Epo secretion from genetically engineered muscles allowed long-term correction of the disease in the mouse, repeated injections of rHuEpo were disappointing in human patients. Whether different mechanisms operate in humans and mice or whether Epo exhibits different biological activity depending on the administration route is currently unknown. We provide evidence that mechanisms recruited over a 36-week follow-up in beta-thalassemic mice were similar to those acting during stress-induced erythropoiesis in humans. beta-Thalassemic mice were rendered steadily normocythemic by the intramuscular injection of a tetracycline-inducible AAV vector encoding mouse Epo. Doxycycline dosage was adapted to hematocrit. Circulating red blood cells essentially synthesized beta-minor globin, the mouse equivalent to human gamma-globin. Quantification of erythroid progenitors indicated a steady-state expansion of erythroid burst-forming units programmed for beta-minor globin synthesis and a hastening of their maturation to hemoglobin-synthesizing cells. We discuss hypotheses that could account for the failure to recruit this mechanism over the long term in beta-thalassemic patients and raise the possibility of Epo gene therapy trials to treat beta-thalassemia.

  8. Pathophysiology of reversible sudden deafness--epidemiological study.

    OpenAIRE

    Ohsaki, Katsuichiro; Aoyama, Hideyasu

    1983-01-01

    Many aspects of the etiology and pathophysiology of reversible sudden deafness remain obscure. In order to better understand the pathophysiology of reversible sudden deafness we compared the results of two therapies which have different mechanisms of action. The results of therapy with tranexamic acid alone in 49 cases (57 ears) of sudden deafness were compared with the results of treatment with so-called antisludging agents in 65 cases (69 ears) using the chi square contingency test. The sam...

  9. Pathophysiology of reversible sudden deafness--epidemiological study.

    OpenAIRE

    Ohsaki, Katsuichiro; Aoyama, Hideyasu

    1983-01-01

    Many aspects of the etiology and pathophysiology of reversible sudden deafness remain obscure. In order to better understand the pathophysiology of reversible sudden deafness we compared the results of two therapies which have different mechanisms of action. The results of therapy with tranexamic acid alone in 49 cases (57 ears) of sudden deafness were compared with the results of treatment with so-called antisludging agents in 65 cases (69 ears) using the chi square contingency test. The sam...

  10. Synthesis of mimic molecularly imprinted ordered mesoporous silica adsorbent by thermally reversible semicovalent approach for pipette-tip solid-phase extraction-liquid chromatography fluorescence determination of estradiol in milk.

    Science.gov (United States)

    Wang, Lu; Yan, Hongyuan; Yang, Chunliu; Li, Zan; Qiao, Fengxia

    2016-07-22

    A mimic molecularly imprinted ordered mesoporous silica (MIOMS) adsorbent was prepared utilizing a thermally reversible semicovalent approach. The thermally reversible covalent template-monomer complex was firstly synthesized by employing 4,4'-sulfonyldiphenol (BPS) and (3-isocyanatopropyl) triethoxysilane (ICPTES) as template and monomer, respectively. The template-monomer complex was incorporated into ordered mesoporous silica via a simple self-assembly process. The adsorption experiment illustrated that the imprint-removed silica (MIOMS-ir) had higher special recognition ability (250μgg(-1)) for estradiol (E2) than the non-imprinted silica (NIOMS-ir) (25μgg(-1)). MIOMS-ir was applied as an adsorbent in pipette-tip solid-phase extraction (PT-SPE) coupled with liquid chromatography-fluorescence detector (LC-FLD) for determination of E2 in milk samples. Under the optimized conditions, only 3mg of the adsorbent, 0.3mL of water as washing solvent, and 0.5mL of acetonitrile-acetic acid (96:4, v/v) as elution solvent were used in the pretreatment procedure of milk samples. Good calibration linearity was obtained in a range of 25ngL(-1) to 1000ngL(-1), and the recoveries at three spiked levels were ranged from 95.4% to 107.0% with relative standard deviations (RSDs) ≤3.1% (n=3). The proposed MIOMS-ir-PT-SPE-LC-FLD method combined the advantages of PT-SPE and ordered mesoporous material such as ease assembly, low cost, high extraction efficiency and large specific surface area, so it is a potential pretreatment strategy for the extraction and determination of E2 in complex milk samples.

  11. Structural modifications of dicationic acetylcholinesterase reactivators studied under ion-pairing mechanism in reversed-phase liquid chromatography.

    Science.gov (United States)

    Radulescu, Medeea; Kuca, Kamil; Musilek, Kamil; David, Victor

    2014-11-01

    A study focused on the chromatographic behavior of several acetylcholinesterase reactivators under ion-pairing mechanism is reported. Among these reactivators, dicationic oximes and carbamoyl-based pyridinium congeners were studied, which form ion pairs with alkylsulfonate anions. This mechanism was studied for some major experimental parameters, such as the chain length of the ion-pairing agent added to the aqueous phase, its concentration, temperature, and nature of the organic modifier from mobile phase. Retention data showed one or two possibilities of forming ion pairs and the tautomerism of the studied reactivators, for different pH values of the aqueous component. Double sigmoid shapes were obtained for the studied compounds for the dependence between retention factor and pH, indicating the possibility of one or two tautomeric equilibria: at pH close to 7 these compounds are not stable as dicationic species and they participate in the retention process as nitroso forms, which are not able to form ion pairs with alkylsulfonates. The dependences of the retention factor on the organic modifier content from mobile phase were linear. Two complementary theoretical models were used to explain the functional dependences for the retention data on the experimental parameters.

  12. High-cycle fatigue of 10M Ni-Mn-Ga magnetic shape memory alloy in reversed mechanical loading

    Science.gov (United States)

    Aaltio, I.; Soroka, A.; Ge, Y.; Söderberg, O.; Hannula, S.-P.

    2010-07-01

    Application of Ni-Mn-Ga magnetic shape memory alloys in magnetic-field-induced actuation relies on their performance in long-term high-cycle fatigue. In this paper the performance and changes in the microstructure of a Ni-Mn-Ga 10M martensite single crystal material are reported in a long-term mechanically induced shape change cycling. The longest test was run for 2 × 109 cycles at a frequency of 250 Hz and a strain amplitude of ± 1%. After the test a clear increase of the dynamic stiffness of the material was detected. Three specimens out of ten were cycled until fracture occurred and their fracture mechanism was studied. It was observed that the macroscopic crack growth took place roughly at a 45° angle with respect to the loading direction that was along the lang100rang crystallographic direction of the sample. The macroscopic fracture plane seemed to correspond roughly to the {111} crystal planes. On a microscopic scale the fracture propagated in a step-like manner at least partly along crystallographic planes. The steps at the fracture plane correspond to the {101} twin planes, with the height of steps along the lang101rang direction. The final fracture of the samples occurred in a brittle manner after the critical stress was exceeded.

  13. Plasma catecholamines in hypertension and pheochromocytoma determined using ion-pair reversed-phase chromatography with amperometric detection: investigation of the separation mechanism and clinical methodology.

    Science.gov (United States)

    Krstulović, A M; Dziedzic, S W; Bertani-Dziedzic, L; DiRico, D E

    1981-11-06

    The retention behavior of catecholamines (CAs) in ion-pair reversed-phase chromatography is examined. From the effects of pH, ionic strength and a secondary ion-pairing reagent (citric acid), under our chromatographic conditions, the retention behavior can be explained by assuming a mixed ion-exchange mechanism with octyl sulfate and citrate, on the column and in the mobile phase, respectively. The developed separation method was applied to the analysis of CAs in plasma samples purified by alumina adsorption and detected amperometrically. This method provides the basis for the determination of the short-term magnitude of CA response to physical and physiological interventions, as well as the baseline CA levels in essential hypertension and pheochromocytoma. The results seen for norepinephrine and epinephrine are consistent with eh funcitonal roles of these CAs as hormones or peripheral transmitters.

  14. [Reversal effect of LBH589 alone or in combination with bortezomib on drug-resistance in myeloid leukemia and its mechanism].

    Science.gov (United States)

    Jiang, Xue-Jie; Meng, Fan-Yi; Zhou, Hong-Sheng; Wang, Qiang; Wu, Fu-Qun; Huang, Kai-Kai; Huang, Ming; Wang, Zhi-Xiang; Chen, Wei-Wei

    2011-08-01

    To investigate reversal effect of histone deacetylase inhibitor LBH589 alone or in combination with proteasome inhibitor bortezomib on drug resistance in acute myeloid leukemia (AML) and its mechanism. Ex vivo cultures of HL-60/ADM cells and fresh refractory AML cells were treated with LBH589, bortezomib or their combination at varying concentrations. Proliferation capacity, apoptosis rate and reversal of drug resistance were evaluated by MTT assay, dual staining of Hoechst 33342 and Annexin VFITC/PI by flow cytometry, and adriamycin uptake rate with proliferation inhibition, respectively. The change of signal pathway at protein level was analyzed by Western blot. Synergistic cytotoxicity was observed in the combination treatment with LBH589 and bortezomib against HL-60/ADM cells, as well as the fresh AML cells, the most powerful synergy being observed at 21 nmol/L LBH589 plus 12 nmol/L bortezomib, with CI values of 0.531 and 0.498, respectively by Calcusyn software analysis. Moreover, the accumulation of adriamycin in HL-60/ADM cells was increased more in combination treatment [(64.81 +/- 3.69)%] than in either LBH589 [(28.96 +/- 2.52)%] or bortezomib [(37.29 +/- 3.71)%] alone (P kinase (PI3K)/Akt/nuclear factor-kappaB (NF-kappaB) signaling pathway. Combination treatment of drug resistant AML cells with LBH589 and bortezomib produces a synergistic effect of in creating sensitivity to chemotherapy. The mechanism may be mainly resulted from inhibition of PI3K/ Akt/NF-kappaB signaling pathway.

  15. SISGR -- Domain Microstructures and Mechanisms for Large, Reversible and Anhysteretic Strain Behaviors in Phase Transforming Ferroelectric Materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu U. [Michigan Technological Univ., Houghton, MI (United States)

    2013-12-06

    This four-year project (including one-year no-cost extension) aimed to advance fundamental understanding of field-induced strain behaviors of phase transforming ferroelectrics. We performed meso-scale phase field modeling and computer simulation to study domain evolutions, mechanisms and engineering techniques, and developed computational techniques for nanodomain diffraction analysis; to further support above originally planned tasks, we also carried out preliminary first-principles density functional theory calculations of point defects and domain walls to complement meso-scale computations as well as performed in-situ high-energy synchrotron X-ray single crystal diffraction experiments to guide theoretical development (both without extra cost to the project thanks to XSEDE supercomputers and DOE user facility Advanced Photon Source).

  16. The study of resistant mechanisms and reversal in an imatinib resistant Ph+ acute lymphoblastic leukemia cell line.

    Science.gov (United States)

    Xing, Hongyun; Yang, Xi; Liu, Ting; Lin, Juan; Chen, Xiaoyi; Gong, Yuping

    2012-04-01

    In this study, we established an imatinib resistant Ph+ acute lymphoblastic leukemia (ALL) cell line SUP-B15/RI in vitro and studied the mechanism of imatinib resistance. Our results showed that the BCR-ABL1 fusion gene and the mdr1 gene were 6.1 times and 1.7 times, respectively, as high as that of parental SUP-B15 cell line. We found no mutation in the Abl kinase domain of SUP-B15/RI. Furthermore, the detection of cell signaling pathway of PI3K/AKT/mTOR, RAS/RAF, NF-κB, JNK and STAT showed the up-regulation of phosphorylation of AKT, mTOR, P70S6K, and RAF, ERK, and MEK, down-regulation of PTEN and 4EBP-1, and no change in other cell signaling pathways in SUP-B15/RI. However, dasatinib and nilotinib showed partial resistance. Interestingly, bortezomib had no resistance. Imatinib combination with rapamycin had synergistic effect on overcoming the resistance. Altogether, over-expression of BCR-ABL1 and mdr1 gene were involved in the resistance mechanisms, and up-regulation of the cell signaling pathways of PI3K/AKT/mTOR, RAS/RAF in SUP-B15/RI cell line may be correlated with them. The SUP-B15/RI cell line was also resistant to the second generation tyrosine kinase, dasatinib, and nilotinib, not bortezomib. The combination of imatinib with rapamycin can partially overcome the resistance and blockade of the ubiquitin-proteasome can be also a promising pathway to overcome imatinib resistance. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Adsorption behavior and mechanisms of ciprofloxacin from aqueous solution by ordered mesoporous carbon and bamboo-based carbon.

    Science.gov (United States)

    Peng, Xiaoming; Hu, Fengping; Lam, Frank L-Y; Wang, Yajun; Liu, Zhanmeng; Dai, Hongling

    2015-12-15

    The performances of ordered mesoporous carbon CMK-3 (OMC), bamboo-based carbon (BC), and these two kinds of adsorbents modified by thermal treatment in the ammonia atmosphere at high temperatures were evaluated for the removal fluoroquinolone antibiotic (ciprofloxacin) from aqueous solution. The adsorption behavior of ciprofloxacin (CIP) onto OMC and BC including adsorption isotherms and kinetics were investigated. The effect of various factors (pH, ionic strength and temperature) on the adsorption process was also investigated. The results demonstrated that the modified OMC and BC can further enhance the adsorption capacity due to introduce of alkaline nitrogen functionalities on the carbon surface. And their maximum adsorption capacity reached as high as 233.37mgg(-1) and 362.94mgg(-1) under the same experimental conditions, respectively. This is primarily ascribed to the positive effect of the surface basicity. The highest sorption was observed at the lowest solubility, which indicated that hydrophobic interaction was the dominant sorption mechanism for CIP uptake onto the four adsorbents. The adsorption data of antibiotics was analyzed by Langmuir and Freundlich model, and the better correlation was achieved by the Langmuir isotherm. The kinetic data showed that the adsorption of CIP onto OMC and BC follow closely the pseudo-second order model. The removal efficiency and adsorption capacity increased with increasing temperature. The results of thermodynamic study indicated that the adsorption process was a spontaneous and endothermic. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. A neural model for temporal order judgments and their active recalibration: a common mechanism for space and time?

    Directory of Open Access Journals (Sweden)

    Mingbo eCai

    2012-11-01

    Full Text Available When observers experience a constant delay between their motor actions and sensory feedback, their perception of the temporal order between actions and sensations adapt (Stetson et al., 2006a. We present here a novel neural model that can explain temporal order judgments (TOJs and their recalibration. Our model employs three ubiquitous features of neural systems: 1 information pooling, 2 opponent processing, and 3 synaptic scaling. Specifically, the model proposes that different populations of neurons encode different delays between motor-sensory events, the outputs of these populations feed into rivaling neural populations (encoding before and after, and the activity difference between these populations determines the perceptual judgment. As a consequence of synaptic scaling of input weights, motor acts which are consistently followed by delayed sensory feedback will cause the network to recalibrate its point of subjective simultaneity. The structure of our model raises the possibility that recalibration of TOJs is a temporal analogue to the motion aftereffect. In other words, identical neural mechanisms may be used to make perceptual determinations about both space and time. Our model captures behavioral recalibration results for different numbers of adapting trials and different adapting delays. In line with predictions of the model, we additionally demonstrate that temporal recalibration can last through time, in analogy to storage of the motion aftereffect.

  19. 物流行业对城市货运共享枢纽的需求%The Study on the Theoretical Foundation of Reverse Logistics and Its Safeguard Mechanism in the Context of Low-carbon Economy

    Institute of Scientific and Technical Information of China (English)

    艾美利亚·C·里根[美; 托马斯·F·格勒博

    2011-01-01

    城市货运共享枢纽的问题从20世纪70年代开始受到关注,当时的情况是,随着城市间货物运输活动的效率不断提高,城市地区内通过货车进行货物运输的成本却大幅增加。早期研究建议建立城市货运共享枢纽,使货车运输企业能够将零散的货物集中起来。过去几年,一方面为了满足承运商装卸货物的需求,另一方面为了给货车司机在市中心周边提供一个交通高峰期轮候的场所,“城市港”的概念开始受到越来越多的关注。本文采用最新获取的调查数据,运用需求的有序概率模型来考察货运公司对此类设施是否感兴趣。%Developing reverse logistics is an important means to achieve low-carbon economy, and stakeholder theory, game theory, sustainable development theory, recycling economy theory, externality theory and ecological economics are its solid theoretical foundation. At this stage the problems in the development of reverse logistics include inadequate laws and regulations, low level of technology, uncertainty of supply and demand and inadequate network, which seriously hindered the development of reverse logistics. Safeguard mechanisms including government, business and citizen participation, adequate laws and regulations, advanced technologies, and efficient incentive measures should be established to promote the healthy and orderly development of reverse logistics.

  20. Simulation of crack coalescence mechanism underneath single and double disc cutters by higher order displacement discontinuity method

    Institute of Scientific and Technical Information of China (English)

    Mohammad Fatehi Marji

    2015-01-01

    The present research is focused on the numerical crack coalescence analysis of the micro-cracks and cracks produced during the cutting action of TBM disc cutters. The linear elastic fracture mechanics (LEFM) concepts and the maximum tangential stress criterion are used to investigate the micro crack propagation and its direction underneath the excavating discs. A higher order displacement discontinuity method with quadratic displacement discontinuity elements is used to estimate the stress intensity factors near the crack tips. Rock cutting mechanisms under single and double type discs are simulated by the proposed numerical method. The main purposes of the present modeling are to simulate the chip formation process of indented rocks by single and double discs. The effects of specific disc parameters (except speed) on the thrust force Ft, the rolling force Fr, and the specific energy ES are investigated. It has been shown that the specific energy (energy required to cut through a unit volume of rock) of the double disc is less than that of the single disc. Crack propagation in rocks under disc cutters is numerically modeled and the optimum ratio of disc spacing S to penetration depth Pd (i.e. S/Pd ratio) of about 10 is obtained, which is in good agreement with the theoretical and experimental results cited in the literature.

  1. Emerging quantum mechanics: Coefficient of second-order coherence from classical random fields interacting with threshold type detectors

    Science.gov (United States)

    Khrennikov, Andrei

    2014-11-01

    This paper is a contribution to the project "emergent quantum mechanics" unifying a variety of attempts to treat quantum mechanics (QMs) as emergent from other theories pretending on finer descriptions of quantum phenomena. More concretely it is about an attempt to model detection probabilities predicted by QM for single photon states by using classical random fields interacting with detectors of the threshold type. Continuous field model, prequantum classical statistical field theory (PCSFT), was developed in recent years and its predictions about probabilities and correlations match well with QM. The main problem is to develop the corresponding measurement theory which would describe the transition from continuous fields to discrete events, "clicks of detectors". Some success was achieved and the click-probabilities for quantum observables can be derived from PCSFT by modeling interaction of fields with the threshold type detectors. However, already for the coefficient of second-order coherence g2(0) calculations are too complicated and only an estimation of g2(0) was obtained. In this paper, we present results of numerical simulation based on PCSFT and modeling of interaction with threshold type detectors. The "prequantum random field" interacting with a detector is modeled as the Brownian motion in the space of classical fields (Wiener process in complex Hilbert space). Simulation for g2(0) shows that this coefficient approaches zero with increase of the number of detections.

  2. The influence of the "cage effect" on the mechanism of reversible bimolecular multistage chemical reactions in solutions.

    Science.gov (United States)

    Doktorov, Alexander B

    2015-08-21

    Manifestations of the "cage effect" at the encounters of reactants are theoretically treated by the example of multistage reactions in liquid solutions including bimolecular exchange reactions as elementary stages. It is shown that consistent consideration of quasi-stationary kinetics of multistage reactions (possible only in the framework of the encounter theory) for reactions proceeding near reactants contact can be made on the basis of the concepts of a "cage complex." Though mathematically such a consideration is more complicated, it is more clear from the standpoint of chemical notions. It is established that the presence of the "cage effect" leads to some important effects not inherent in reactions in gases or those in solutions proceeding in the kinetic regime, such as the appearance of new transition channels of reactant transformation that cannot be caused by elementary event of chemical conversion for the given mechanism of reaction. This results in that, for example, rate constant values of multistage reaction defined by standard kinetic equations of formal chemical kinetics from experimentally measured kinetics can differ essentially from real values of these constants.

  3. Temperature-induced reversible first-order single crystal to single crystal phase transition in Boc-γ(4)(R)Val-Val-OH: interplay of enthalpy and entropy.

    Science.gov (United States)

    Pal, Rumpa; Reddy, M B Madhusudana; Dinesh, Bhimareddy; Balaram, Padmanabhan; Guru Row, Tayur N

    2014-10-01

    Crystals of Boc-γ(4)(R)Val-Val-OH undergo a reversible first-order single crystal to single crystal phase transition at Tc ≈ 205 K from the orthorhombic space group P22121 (Z' = 1) to the monoclinic space group P21 (Z' = 2) with a hysteresis of ∼2.1 K. The low-temperature monoclinic form is best described as a nonmerohedral twin with ∼50% contributions from its two components. The thermal behavior of the dipeptide crystals was characterized by differential scanning calorimetry experiments. Visual changes in birefringence of the sample during heating and cooling cycles on a hot-stage microscope with polarized light supported the phase transition. Variable-temperature unit cell check measurements from 300 to 100 K showed discontinuity in the volume and cell parameters near the transition temperature, supporting the first-order behavior. A detailed comparison of the room-temperature orthorhombic form with the low-temperature (100 K) monoclinic form revealed that the strong hydrogen-bonding motif is retained in both crystal systems, whereas the non-covalent interactions involving side chains of the dipeptide differ significantly, leading to a small change in molecular conformation in the monoclinic form as well as a small reorientation of the molecules along the ac plane. A rigid-body thermal motion analysis (translation, libration, screw; correlation of translation and libration) was performed to study the crystal entropy. The reversible nature of the phase transition is probably the result of an interplay between enthalpy and entropy: the low-temperature monoclinic form is enthalpically favored, whereas the room-temperature orthorhombic form is entropically favored.

  4. Mechanical properties of ground state structures in substitutional ordered alloys: High strength, high ductility and high thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Tawancy, H.M., E-mail: tawancy@kfupm.edu.sa [Center for Engineering Research, Research Institute, King Fahd University of Petroleum and Minerals, KFUPM Box 1639, Dhahran 31261 (Saudi Arabia); Aboelfotoh, M.O., E-mail: oaboelfotoh@gmail.com [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27606 (United States)

    2014-05-01

    We have studied the effect of atom arrangements in the ground state structures of substitutional ordered alloys on their mechanical properties using nickel–molybdenum-based alloys as model systems. Three alloys with nominal compositions of Ni–19.43 at% Mo, Ni–18.53 at% Mo–15.21 at% Cr and Ni–18.72 at% Mo–6.14 at% Nb are included in the study. In agreement with theoretical predictions, the closely related Pt{sub 2}Mo-type, DO{sub 22} and D1{sub a} superlattices with similar energies are identified by electron diffraction of ground state structures, which can directly be derived from the parent disordered fcc structure by minor atom rearrangements on {420}{sub fcc} planes. The three superlattices are observed to coexist during the disorder–order transformation at 700 °C with the most stable superlattice being determined by the exact chemical composition. Although most of the slip systems in the parent disordered fcc structure are suppressed, many of the twinning systems remain operative in the superlattices favoring deformation by twinning, which leads to considerable strengthening while maintaining high ductility levels. Both the Pt{sub 2}Mo-type and DO{sub 22} superlattices are distinguished by high strength and high ductility due to their nanoscale microstructures, which have high thermal stability. However, the D1{sub a} superlattice is found to exhibit poor thermal stability leading to considerable loss of ductility, which has been correlated with self-induced recrystallization by migration of grain boundaries.

  5. Cognitive mechanisms for transitive inference performance in rhesus monkeys: measuring the influence of associative strength and inferred order.

    Science.gov (United States)

    Gazes, Regina Paxton; Chee, Nicholas W; Hampton, Robert R

    2012-10-01

    If Ben is taller than Emily and Emily is taller than Dina, one can infer that Ben is taller than Dina. This process of inferring relations between stimuli based on shared relations with other stimuli is called transitive inference (TI). Many species solve TI tasks in which they learn pairs of overlapping stimulus discriminations (A+B-, B+C-, etc.) and are tested with non-adjacent novel test pairings (BD). When relations between stimuli are determined by reinforcement (A is reinforced when paired with B, B when paired with C), performance can be controlled by the associative values of individual stimuli or by logical inference. In Experiment 1 rhesus monkeys (Macaca mulatta) chose the higher ranked item on non-adjacent test trials after training on a 7-image TI task. In Experiment 2 we measured the associative values of 7 TI images and found that these values did not correlate with choice in TI tests. In Experiment 3 large experimental manipulations of the associative value of images did influence performance in some TI test pairings, but performance on other pairs was consistent with the implied order. In Experiment 4 monkeys linked two previously learned 7-item lists into one 14-item list after training with a single linking pair. Linking cannot be explained by associative values. Associative value can control choice in TI tests in at least some extreme circumstances. Implied order better explains most TI choices in monkeys, and is a more viable mechanism for TI of social dominance, which has been observed in birds and fish.

  6. HIV-1 Reverse Transcriptase Still Remains a New Drug Target: Structure, Function, Classical Inhibitors, and New Inhibitors with Innovative Mechanisms of Actions

    Directory of Open Access Journals (Sweden)

    Francesca Esposito

    2012-01-01

    Full Text Available During the retrotranscription process, characteristic of all retroviruses, the viral ssRNA genome is converted into integration-competent dsDNA. This process is accomplished by the virus-coded reverse transcriptase (RT protein, which is a primary target in the current treatments for HIV-1 infection. In particular, in the approved therapeutic regimens two classes of drugs target RT, namely, nucleoside RT inhibitors (NRTIs and nonnucleoside RT inhibitors (NNRTIs. Both classes inhibit the RT-associated polymerase activity: the NRTIs compete with the natural dNTP substrate and act as chain terminators, while the NNRTIs bind to an allosteric pocket and inhibit polymerization noncompetitively. In addition to these two classes, other RT inhibitors (RTIs that target RT by distinct mechanisms have been identified and are currently under development. These include translocation-defective RTIs, delayed chain terminators RTIs, lethal mutagenesis RTIs, dinucleotide tetraphosphates, nucleotide-competing RTIs, pyrophosphate analogs, RT-associated RNase H function inhibitors, and dual activities inhibitors. This paper describes the HIV-1 RT function and molecular structure, illustrates the currently approved RTIs, and focuses on the mechanisms of action of the newer classes of RTIs.

  7. Improvements in the mechanical properties of the 18R {r_reversible} 6R high-hysteresis martensitic transformation by nanoprecipitates in CuZnAl alloys

    Energy Technology Data Exchange (ETDEWEB)

    Castro Bubani, Franco de, E-mail: franco@cab.cnea.gov.ar [Centro Atomico Bariloche (CNEA), Av. E. Bustillo km. 9,5 (8400) S.C. de Bariloche (Argentina); CONICET (Argentina); Sade, Marcos, E-mail: sade@cab.cnea.gov.ar [Centro Atomico Bariloche (CNEA), Av. E. Bustillo km. 9,5 (8400) S.C. de Bariloche (Argentina); CONICET (Argentina); Instituto Balseiro, Universidad Nacional de Cuyo (Argentina); Lovey, Francisco, E-mail: lovey@cab.cnea.gov.ar [Centro Atomico Bariloche (CNEA), Av. E. Bustillo km. 9,5 (8400) S.C. de Bariloche (Argentina); Instituto Balseiro, Universidad Nacional de Cuyo (Argentina)

    2012-05-01

    Highlights: Black-Right-Pointing-Pointer Mechanical properties of 6R martensite in CuZnAl are improved by nanoprecipitates. Black-Right-Pointing-Pointer Plastic deformation of 6R martensite is suppressed during 18R-6R transition. Black-Right-Pointing-Pointer 20% recoverable strain is obtained in full {beta}-18R-6R transition in single crystals. Black-Right-Pointing-Pointer 10% recoverable strain is obtained in 18R-6R transition with 150 MPa hysteresis. Black-Right-Pointing-Pointer The material could be used in mechanical damping or other applications. - Abstract: The 18R {r_reversible} 6R martensite-martensite transformation in Cu-based alloys exhibits large hysteresis, large pseudoelastic strain and weak transformation stress dependence on temperature. However, concomitant plastic deformation taking place in the 6R phase inhibits the use of these properties for applications. A novel approach to minimizing or even suppressing 6R plastic deformation during the 18R-6R transformation in CuZnAl shape-memory alloy single crystals with electronic concentration e/a = 1.48 is presented. The method is based on a thermal treatment that introduces nanoprecipitates in the alloy. Results suggest that the role of CuZnAl shape-memory alloys in engineering should be reconsidered, as many energy damping applications could benefit from the huge hysteresis associated with the 18R-6R transformation, once the 6R plastic deformation is suppressed.

  8. Quantum mechanical reaction probability of triplet ketene at the multireference second-order perturbation level of theory.

    Science.gov (United States)

    Ogihara, Yusuke; Yamamoto, Takeshi; Kato, Shigeki

    2010-09-23

    Triplet ketene exhibits a steplike structure in the experimentally observed dissociation rates, but its mechanism is still unknown despite many theoretical efforts in the past decades. In this paper we revisit this problem by quantum mechanically calculating the reaction probability with multireference-based electronic structure theory. Specifically, we first construct an analytical potential energy surface of triplet state by fitting it to about 6000 ab initio energies computed at the multireference second-order Mller-Plesset perturbation (MRMP2) level. We then evaluate the cumulative reaction probability by using the transition state wave packet method together with an adiabatically constrained Hamiltonian. The result shows that the imaginary barrier frequency on the triplet surface is 328i cm-1, which is close to the CCSD(T) result (321i cm-1) but is likely too large for reproducing the experimentally observed steps. Indeed, our calculated reaction probability exhibits no signature of steps, reflecting too strong tunneling effect along the reaction coordinate. Nevertheless, it is emphasized that the flatness of the potential profile in the transition-state region (which governs the degree of tunneling) depends strongly on the level of electronic structure calculation, thus leaving some possibility that the use of more accurate theories might lead to the observed steps. We also demonstrate that the triplet potential surface differs significantly between the CASSCF and MRMP2 results, particularly in the transition-state region. This fact seems to require more attention when studying the "nonadiabatic" scenario for the steps, in which the crossing seam between S0 and T1 surfaces is assumed to play a central role.

  9. Effect of the Degree of Soft and Hard Segment Ordering on the Morphology and Mechanical Behavior of Semicrystalline Segmented Polyurethanes

    Energy Technology Data Exchange (ETDEWEB)

    Korley,L.; Pate, B.; Thomas, E.; Hammond, P.

    2006-01-01

    The hierarchical microstructure responsible for the unique energy-absorbing properties of natural materials, like native spider silk and wood, motivated the development of segmented polyurethanes with soft segments containing multiple levels of order. As a first step in correlating the effects of crystallinity in the soft segment phase to the hard segment phase, we chose to examine the morphology and mechanical behavior of polyurethanes containing polyether soft blocks with varying tendencies to crystallize and phase segregate and the evolution of the microstructure with deformation. A series of high molecular weight polyurethanes containing poly(ethylene oxide) (PEO) (1000 and 4600 g/mol) and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) (1900 g/mol) soft segments with varying hard segment content were synthesized using a two-step solution polymerization method. The presence of soft segment crystallinity (PEO 1000 g/mol) was shown to improve the storage modulus of the segmented polyurethanes below the T{sub m} of the soft block and to enhance toughness compared to the PEO-PPO-PEO soft segment polyurethanes. We postulate that this enhancement in mechanical behavior is the result of crystalline soft regions that serve as an additional load-bearing component during deformation. Morphological characterization also revealed that the microstructure of the segmented polyurethanes shifts from soft segment continuous to interconnected and/or hard domain continuous with increasing hard segment size, resulting in diminished ultimate elongation, but enhanced initial moduli and tensile strengths. Tuning the soft segment phase crystallinity may ultimately lead to tougher polyurethane fibers.

  10. Reversal Effect and Mechanisms of Recombinant Human Tumor Necrosis Factor-NC Against the Doxorubicin Resistance in Leukemia K562/Doxorubicin Cells

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jing-hong; CHEN Bo-hua

    2015-01-01

    Objective: To explore the reversal effect and mechanisms of recombinant human tumor necrosis factor-NC (rhTNF-NC) against the doxorubicin (Dox) resistance in chronic myelogenous leukemia (CML) K562/Dox cells. Methods: The chemo-sensitivity of tumor cells dealt with different concentrations of rhTNF-NC to Dox was detected by tetrazolium dye assay (MTT). The intra-cellular Dox accumulation represented by lfuorescence intensity was determined by lfow cytometry (FCM) at the excitation wave length of 488 nm and emission wave length of 550 nm. The expression of multidrug resistance (MDR)-related genes and proteins was analyzed by reverse transcription polymerase chain reaction (RT-PCR) and Western blot assays. Results:After being exposed to gradually increasing concentrations of Dox for 10 consecutive months, K562/Dox cells were more resistant to Dox (nearly 132 times) than Dox-sensitive K562 cells. The IC50 of Dox for K562 and K562/Dox cells were (0.04±0.01) and (5.55±0.08) μmol/L, respectively. When K562/Dox cells were treated with rhTNF-NC at 500, 2 500 or 5 000U/mL, the IC50 of Dox was decreased to (2.22±0.34), (1.41±0.13) and (1.04±0.09) μmol/L, respectively. The concentration-response curves were moved upward by the treatment of rhTNF-NC (P Conclusion: rhTNF-NC can effectively augment the drug accumulation in tumor cells. This is due to the up-regulation of TopoIIα and down-regulation of MDR1, MRP and GSTπ at mRNA expression as well as reduction of P-gp and PKCα expression.

  11. Magnetic ordering and conduction mechanism of different electroactive regions in Lu2NiMnO6

    Science.gov (United States)

    Chanda, Sadhan; Saha, Sujoy; Dutta, Alo; Krishna Murthy, J.; Venimadhav, A.; Shannigrahi, Santiranjan; Sinha, T. P.

    2016-10-01

    The magnetodielectric response of a double perovskite oxide Lu2NiMnO6 (LNMO) synthesised by the sol-gel process has been investigated. The Rietveld refinement of the X-ray diffraction data indicates that the room-temperature crystal structure of LNMO is monoclinic with the space group P21/n, which contains an ordered array of alternate MnO6 and NiO6 octahedra. X-ray photoelectron spectroscopy studies confirm the mix valence state of Mn (4+ and 3+) and Ni (2+ and 3+). The optical band gap (Eg = 1.56 eV) obtained from the UV-Visible absorption spectrum suggests that LNMO is a semiconductor. The field cooled and zero-field cooled measurements show the ferromagnetic behaviour of the sample with the transition temperature (Tc) = 45 K and a saturation magnetization of 5.2 μB/f.u. is observed at 2.5 K. The temperature and frequency dependent dielectric measurements reveal colossal values of the dielectric constant, which are interpreted by the Maxwell-Wagner interfacial polarization. The temperature dependence of the bulk dc conductivity indicates a variable-range-hopping mechanism. The saturation polarization value is estimated to be 232 μC/m2 from the pyroelectric current measurement. A negative magnetodielectric effect of 1% is observed at the paramagnetic to ferromagnetic transition temperature. The electronic structure calculations based on density functional theory have been performed to analyse the magnetic properties of LNMO.

  12. Biodegradable Mg-Zn-Y alloys with long-period stacking ordered structure: optimization for mechanical properties.

    Science.gov (United States)

    Zhao, Xu; Shi, Ling-ling; Xu, Jian

    2013-02-01

    To optimize the mechanical properties for biodegradable orthopedic implant, microstructures and tensile properties of Mg-Zn-Y alloys containing long period stacking ordered (LPSO) phase were investigated. For the as-cast Mg(100-3x)(Zn(1)Y(2))(x) (1 ≤ x ≤ 3) alloys, volume fraction of 18R LPSO phase increases with increasing the contents of Zn and Y. Mg(97)Zn(1)Y(2) alloy exhibits the optimal combination of strength and plasticity. Substitution of bioactive element Ca for Y in the Mg(97)Zn(1)Y(2) does not favor the formation of LPSO phase, but involving the formation of Mg(2)Ca phase. By micro-alloying with Zr as grain refinement agent, morphology of α-Mg in the Mg(96.83)Zn(1)Y(2)Zr(0.17) alloy is changed into the equiaxial shape, together with a significant refinement in grain size to 30 μm. It brings about an improvement not only in strength but also in plasticity, in contrast to the Zr-free alloy. In comparison with the as-cast state, warm-extruded alloys manifest significantly improved properties not only in strength but also in plasticity due to the refinement of α-Mg grain by dynamic recrystallization and the alignment of LPSO phase along extrusion direction.

  13. 蛋白质的反胶团萃取机制及动力学模型研究进展%Advances in Mechanism of Reverse Micelles Extraction of Proteins and Its Dynamics Model

    Institute of Scientific and Technical Information of China (English)

    李宏; 王崇均

    2011-01-01

    Reverse micelles extraction is a new method recently developed which used in the separation and purification of biological active matters (proteins,enzymes). This paper has introduced the principle and mechanism of the reverse micelle extraction of protein,the factors affecting the stability of protein in reverse micelles, the improved technology of protein reverse extraction using reverse micelles,the dynamics research of enzyme in reverse micelles and the application and prospect of reverse micelles technology.%反胶团萃取是近年发展起来的分离和纯化生化物质的新方法,本文介绍了反胶团萃取蛋白质技术的原理和机制、影响反胶团中蛋白质稳定性的因素,改进的蛋白质反萃取工艺,反胶团的酶动力学研究以及反胶团萃取技术的研究展望.

  14. 基于算术机制的可辨识次序水印方案%Watermarking Capable of Identifying Embedding Order Based on an Arithmetic Mechanism

    Institute of Scientific and Technical Information of China (English)

    张新鹏; 王朔中; 张开文

    2003-01-01

    A digital watermark as a means for copyright protection may be crippled when a fake mark is embedded on top of it since both watermarks are detectable. In dealing with this problem, a watermarking scheme that does not satisfy the law of commutation is proposed. In this scheme, an order function based on an arithmetic mechanism is employed to identify the embedding order without affecting detection of the regular watermark. An earlier watermark corresponds to a larger value of the order function. In this way, the embedding order or watermarks can be identified according to the order function.

  15. REVERSE SUPPLY CHAIN

    Directory of Open Access Journals (Sweden)

    Tomasz DOMAGAŁA

    2013-10-01

    Full Text Available The paper focuses on the presentation of the reverse supply chain, of which the role in the modern business grows along with the increasing number of environmental regulations and possibilities of reducing an operating cost. The paper also describes main problems in developing the profitable chain and possibilities to take an action in order to overcome them.

  16. Reversible Computing

    Science.gov (United States)

    1980-02-01

    will have been introduced. 9. Reversible celular autemata We shall assume the reader to have some familiarity with the concept of cel- lular...10003 Mr. Kin B. Thcmpson 1 copy Technical Director Information Systems Divisia.i Naval Research Laboratory (OP-91T) Technical Information Division

  17. Long-term survival in elderly patients with a do-not-intubate order treated with noninvasive mechanical ventilation

    Directory of Open Access Journals (Sweden)

    Riario-Sforza GG

    2011-04-01

    Full Text Available Paolo Scarpazza1, Cristoforo Incorvaia2, Paolo Amboni3, Giuseppe di Franco1, Stefania Raschi1, Pierfranco Usai1, Monica Bernareggi1, Cristiano Bonacina1, Chiara Melacini1, Roberta Cattaneo1, Serena Bencini1, Chiara Pravettoni2, Gian Galeazzo Riario-Sforza2, Gianni Passalacqua4, Walter Casali11Divisione di Broncopneumotisiologia, Ospedale Civile, Vimercate, Italy; 2Pulmonary Rehabilitation, Istituti Clinici di Perfezionamento, Milan, Italy; 3Clinical Chemistry Laboratory, Ospedali Riuniti, Bergamo, Italy; 4Allergy and Respiratory Diseases, University Of Genoa, Genoa, ItalyBackground: Noninvasive mechanical ventilation (NIMV is an effective tool in treating patients with acute respiratory failure (ARF, since it reduces both the need for endotracheal intubation and the mortality in comparison with nonventilated patients. A particular issue is represented by the outcome of NIMV in patients referred to the emergency department for ARF and with a do-not-intubate (DNI status because of advanced age or excessively critical conditions. This study evaluated long-term survival in a group of elderly patients with acute hypercapnic ARF who had a DNI order and who were successfully treated by NIMV.Methods: The population consisted of 54 patients with a favorable outcome after NIMV for ARF. They were followed up for 3 years by regular control visits, with at least one visit every 4 months, or as needed according to the patient’s condition. Of these, 31 continued NIMV at home and 23 were on long-term oxygen therapy (LTOT alone.Results: A total of 16 of the 52 patients had not survived at the 1-year follow-up, and another eight patients died during the 3-year observation, with an overall mortality rate of 30.8% after 1 year and 46.2% after 3 years. Comparing patients who continued NIMV at home with those who were on LTOT alone, 9 of the 29 patients on home NIMV died (6 after 1 year and 3 after 3 years and 15 of the 23 patients on LTOT alone died (10 after 1

  18. Composition and stabilization mechanisms of organic matter in soils and sediments eroded from granitic, low-order catchments in the Sierra Nevada, California

    OpenAIRE

    Stacy, Erin Michele

    2012-01-01

    Soil erosion can alter the mechanisms of organic matter (OM) storage and persistence in soil, including aggregation, burial, and organo-mineral associations. I studied how extended transport of topsoil and associated OM alters OM stabilization mechanisms by comparing soil from different landform positions with sediment exported from eight, low-order watersheds in the Sierra Nevada, California. To assess the relative importance of different stabilization mechanisms, I separated free, unprotect...

  19. Structural Mechanism Underpinning Cross-reactivity of a CD8+ T-cell Clone That Recognizes a Peptide Derived from Human Telomerase Reverse Transcriptase*

    Science.gov (United States)

    Cole, David K.; van den Berg, Hugo A.; Lloyd, Angharad; Crowther, Michael D.; Beck, Konrad; Ekeruche-Makinde, Julia; Miles, John J.; Bulek, Anna M.; Dolton, Garry; Schauenburg, Andrea J.; Wall, Aaron; Fuller, Anna; Clement, Mathew; Laugel, Bruno; Rizkallah, Pierre J.; Wooldridge, Linda; Sewell, Andrew K.

    2017-01-01

    T-cell cross-reactivity is essential for effective immune surveillance but has also been implicated as a pathway to autoimmunity. Previous studies have demonstrated that T-cell receptors (TCRs) that focus on a minimal motif within the peptide are able to facilitate a high level of T-cell cross-reactivity. However, the structural database shows that most TCRs exhibit less focused antigen binding involving contact with more peptide residues. To further explore the structural features that allow the clonally expressed TCR to functionally engage with multiple peptide-major histocompatibility complexes (pMHCs), we examined the ILA1 CD8+ T-cell clone that responds to a peptide sequence derived from human telomerase reverse transcriptase. The ILA1 TCR contacted its pMHC with a broad peptide binding footprint encompassing spatially distant peptide residues. Despite the lack of focused TCR-peptide binding, the ILA1 T-cell clone was still cross-reactive. Overall, the TCR-peptide contacts apparent in the structure correlated well with the level of degeneracy at different peptide positions. Thus, the ILA1 TCR was less tolerant of changes at peptide residues that were at, or adjacent to, key contact sites. This study provides new insights into the molecular mechanisms that control T-cell cross-reactivity with important implications for pathogen surveillance, autoimmunity, and transplant rejection. PMID:27903649

  20. Involvement of suppressive B-lymphocytes in the mechanism of tolerogenic dendritic cell reversal of type 1 diabetes in NOD mice.

    Science.gov (United States)

    Di Caro, Valentina; Phillips, Brett; Engman, Carl; Harnaha, Jo; Trucco, Massimo; Giannoukakis, Nick

    2014-01-01

    The objective of the study was to identify immune cell populations, in addition to Foxp3+ T-regulatory cells, that participate in the mechanisms of action of tolerogenic dendritic cells shown to prevent and reverse type 1 diabetes in the Non-Obese Diabetic (NOD) mouse strain. Co-culture experiments using tolerogenic dendritic cells and B-cells from NOD as well as transgenic interleukin-10 promoter-reporter mice along with transfer of tolerogenic dendritic cells and CD19+ B-cells into NOD and transgenic mice, showed that these dendritic cells increased the frequency and numbers of interleukin-10-expressing B-cells in vitro and in vivo. The expansion of these cells was a consequence of both the proliferation of pre-existing interleukin-10-expressing B-lymphocytes and the conversion of CD19+ B-lymphcytes into interleukin-10-expressing cells. The tolerogenic dendritic cells did not affect the suppressive activity of these B-cells. Furthermore, we discovered that the suppressive murine B-lymphocytes expressed receptors for retinoic acid which is produced by the tolerogenic dendritic cells. These data assist in identifying the nature of the B-cell population increased in response to the tolerogenic dendritic cells in a clinical trial and also validate very recent findings demonstrating a mechanistic link between human tolerogenic dendritic cells and immunosuppressive regulatory B-cells.

  1. Involvement of suppressive B-lymphocytes in the mechanism of tolerogenic dendritic cell reversal of type 1 diabetes in NOD mice.

    Directory of Open Access Journals (Sweden)

    Valentina Di Caro

    Full Text Available The objective of the study was to identify immune cell populations, in addition to Foxp3+ T-regulatory cells, that participate in the mechanisms of action of tolerogenic dendritic cells shown to prevent and reverse type 1 diabetes in the Non-Obese Diabetic (NOD mouse strain. Co-culture experiments using tolerogenic dendritic cells and B-cells from NOD as well as transgenic interleukin-10 promoter-reporter mice along with transfer of tolerogenic dendritic cells and CD19+ B-cells into NOD and transgenic mice, showed that these dendritic cells increased the frequency and numbers of interleukin-10-expressing B-cells in vitro and in vivo. The expansion of these cells was a consequence of both the proliferation of pre-existing interleukin-10-expressing B-lymphocytes and the conversion of CD19+ B-lymphcytes into interleukin-10-expressing cells. The tolerogenic dendritic cells did not affect the suppressive activity of these B-cells. Furthermore, we discovered that the suppressive murine B-lymphocytes expressed receptors for retinoic acid which is produced by the tolerogenic dendritic cells. These data assist in identifying the nature of the B-cell population increased in response to the tolerogenic dendritic cells in a clinical trial and also validate very recent findings demonstrating a mechanistic link between human tolerogenic dendritic cells and immunosuppressive regulatory B-cells.

  2. Temperature dependence of magnetization reversal mechanism in CoNi/CoO bilayers%CoNi/CoO双层膜磁化反转机制与温度的依赖关系

    Institute of Scientific and Technical Information of China (English)

    宋金涛; 袁淑娟

    2007-01-01

    Exchange coupling and magnetization reversal mechanism in two series of Cox Ni1-x/CoO (30 nm) (x=0.2 and 0.4) bilayers are studied by vector magnetometer. Two components of magnetization are measured parallel and perpendicular to the applied field. At low temperatures, coercivity He ∝ (tFM)-n, n = 1.5 and 1.38 for x = 0.2 and 0.4, respectively, in agreement with the random field model. At room temperature, the coercivity is nearly proportional to the inverse FM layer thickness. In addition to the exchange field and the coercivity, the characteristic of the magnetization reversal mechanism was found to change with temperature. At temperatures below 180 K, magnetization reversal process along the unidirectional axis is accompanied only by nucleation and pinning of domain wall while magnetization rotation is also involved at high temperatures.

  3. A template-dependent dislocation mechanism potentiates K65R reverse transcriptase mutation development in subtype C variants of HIV-1.

    Directory of Open Access Journals (Sweden)

    Dimitrios Coutsinos

    Full Text Available Numerous studies have suggested that the K65R reverse transcriptase (RT mutation develops more readily in subtype C than subtype B HIV-1. We recently showed that this discrepancy lies partly in the subtype C template coding sequence that predisposes RT to pause at the site of K65R mutagenesis. However, the mechanism underlying this observation and the elevated rates of K65R development remained unknown. Here, we report that DNA synthesis performed with subtype C templates consistently produced more K65R-containing transcripts than subtype B templates, regardless of the subtype-origin of the RT enzymes employed. These findings confirm that the mechanism involved is template-specific and RT-independent. In addition, a pattern of DNA synthesis characteristic of site-specific primer/template slippage and dislocation was only observed with the subtype C sequence. Analysis of RNA secondary structure suggested that the latter was unlikely to impact on K65R development between subtypes and that Streisinger strand slippage during DNA synthesis at the homopolymeric nucleotide stretch of the subtype C K65 region might occur, resulting in misalignment of the primer and template. Consequently, slippage would lead to a deletion of the middle adenine of codon K65 and the production of a -1 frameshift mutation, which upon dislocation and realignment of the primer and template, would lead to development of the K65R mutation. These findings provide additional mechanistic evidence for the facilitated development of the K65R mutation in subtype C HIV-1.

  4. Ion irradiation induced effects and magnetization reversal mechanism in (Ni{sub 80}Fe{sub 20}){sub 1−x}Co{sub x} nanowires and nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Naeem, E-mail: naeem.ahmad@iiu.edu.pk [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100090 (China); Spintronics Laboratory, Department of Physics, Faculty of Basic and Applied Sciences (FBAS), International Islamic University H-10, Islamabad 44000 (Pakistan); Iqbal, Javed [Laboratory of Nanoscience and Technology, Department of Physics, International Islamic University, H-10, Islamabad,Pakistan (Pakistan); Chen, J.Y. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100090 (China); Hussain, Asim [Spintronics Laboratory, Department of Physics, Faculty of Basic and Applied Sciences (FBAS), International Islamic University H-10, Islamabad 44000 (Pakistan); Shi, D.W.; Han, X.F. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100090 (China)

    2015-03-15

    The effect of Co on the ferromagnetic characteristics of the Ni{sub 80}Fe{sub 20} nanocylinders having zero magnetostriction and soft magnetic nature is an interesting field of research. The (Ni{sub 80}Fe{sub 20}){sub 1−x}Co{sub x} nanocylinders have been prepared by electrodeposition into commercially available anodized aluminum oxide (AAO) nanoporous templates. The analysis of magnetization reversal from the angular dependence of coercivity has been studied in detail. This angular dependence of coercivity has shown a transition from curling to nucleation mode as a function of field angle for all (Ni{sub 80}Fe{sub 20}){sub 1−x}Co{sub x} nanocylinders depending upon the critical angle. The shape anisotropy, dipole–dipole interactions, surface effects and magnetocrystalline anisotropy have been found to play an effective role for the spontaneous magnetization in nanowires and nanotubes. It has been interestingly observed that the magnetostatic interactions or dipole–dipole interactions are dominant in nanocylinders regardless of its geometry. Furthermore, the prepared samples have been irradiated with He{sup 2+} ions (energy E=2 MeV, fluence=10{sup 14} ions/cm{sup 2} and ion current=16 nA) at room temperature using a 5-UDH-2pelletron tandem accelerator. The irradiations have created defects and these defects have induced changes in magnetization as a result an increase in coercivity as function of the ion fluences is observed. Such kind of behavior in coercivity enhancement and magnetization reduction can also be attributed to the stress relaxation and percolation in nonuniform states of ferromagnetic alloys, respectively. - Highlights: • We have prepared the ferromagnetic NiFeCo nanowires and nanotubes into anodized aluminum oxide templates (AAO) by electrodeposition method. • We have studied the magnetization reversal mechanism from the angle dependent coercivity measured by a hysteresis loop. • The ion irradiation effects on these nanostructures

  5. Reversible thermally induced phase transition in ordered domains of Co(II)-5,10,15,20-tetrakis-(3,5-di-tert-butylphenyl)-porphyrin on Cu(111)

    Science.gov (United States)

    Stark, Michael; Ditze, Stefanie; Thomann, Michael; Lungerich, Dominik; Jux, Norbert; Steinrück, Hans-Peter; Marbach, Hubertus

    2016-08-01

    We investigated the adsorption behavior of Co(II)-5,10,15,20-tetrakis-(3,5-di-tert-butylphenyl)-porphyrin (CoTTBPP) on Cu(111) by scanning tunneling microscopy (STM). At room temperature (RT), the coverage dependent adsorption behavior follows an expected scheme: at low coverage step decoration is found, which evolves into supramolecular domains with a hexagonal order at higher coverage. Interestingly, upon cooling the sample to 180 K the occurrence of a clearly distinguishable coexisting herringbone phase is observed. Upon heating to RT again, the herringbone phase vanishes. Thus a temperature dependent, fully reversible phase transition was observed. High resolution STM micrographs allow for the determination of the intramolecular conformations which are different for the two supramolecular arrangements. In addition, we studied the bias voltage dependent appearance of the molecule in STM and assigned a dominant contribution of the central Co at negative bias voltages close to the Fermi edge to the occupied dz2 orbital. Interestingly, the herringbone phase, which dominates at 180 K, exhibits a significantly higher molecular density than the monomodal hexagonal arrangement at RT, which is in line with the "normal" behavior of freezing substances.

  6. Reversible and efficient activation of HIV-1 cell entry by a tyrosine-sulfated peptide dissects endocytic entry and inhibitor mechanisms.

    Science.gov (United States)

    Platt, Emily J; Gomes, Michelle M; Kabat, David

    2014-04-01

    HIV-1 membranes contain gp120-gp41 trimers. Binding of gp120 to CD4 and a coreceptor (CCR5 or CXCR4) reduces the constraint on metastable gp41, enabling a series of conformational changes that cause membrane fusion. An analytic difficulty occurs because these steps occur slowly and asynchronously within cohorts of adsorbed virions. We previously isolated HIV-1JRCSF variants that efficiently use CCR5 mutants severely damaged in the tyrosine-sulfated amino terminus or extracellular loop 2. Surprisingly, both independent adaptations included gp120 mutations S298N, F313L, and N403S, supporting other evidence that they function by weakening gp120's grip on gp41 rather than by altering gp120 binding to specific CCR5 sites. Although several natural HIV-1 isolates reportedly use CCR5(Δ18) (CCR5 with a deletion of 18 N-terminal amino acids, including the tyrosine-sulfated region) when the soluble tyrosine-sulfated peptide is present, we show that HIV-1JRCSF with the adaptive mutations [HIV-1JRCSF(Ad)] functions approximately 100 times more efficiently and that coreceptor activation is reversible, enabling synchronous efficient entry control under physiological conditions. This system revealed that three-stranded gp41 folding intermediates susceptible to the inhibitor enfuvirtide form slowly and asynchronously on cell surface virions but resolve rapidly, with virions generally forming only one target. Adsorbed virions asynchronously and transiently become competent for entry at 37°C but are inactivated if the CCR5 peptide is absent during their window of opportunity. This competency is conferred by endocytosis, which results in inactivation if the peptide is absent. For both wild-type and adapted HIV-1 isolates, early gp41 refolding steps obligatorily occur on cell surfaces, whereas the final step(s) is endosomal. This system powerfully dissects HIV-1 entry and inhibitor mechanisms. We present a powerful means to reversibly and efficiently activate or terminate HIV-1 entry

  7. Reversed item bias: an integrative model.

    Science.gov (United States)

    Weijters, Bert; Baumgartner, Hans; Schillewaert, Niels

    2013-09-01

    In the recent methodological literature, various models have been proposed to account for the phenomenon that reversed items (defined as items for which respondents' scores have to be recoded in order to make the direction of keying consistent across all items) tend to lead to problematic responses. In this article we propose an integrative conceptualization of three important sources of reversed item method bias (acquiescence, careless responding, and confirmation bias) and specify a multisample confirmatory factor analysis model with 2 method factors to empirically test the hypothesized mechanisms, using explicit measures of acquiescence and carelessness and experimentally manipulated versions of a questionnaire that varies 3 item arrangements and the keying direction of the first item measuring the focal construct. We explain the mechanisms, review prior attempts to model reversed item bias, present our new model, and apply it to responses to a 4-item self-esteem scale (N = 306) and the 6-item Revised Life Orientation Test (N = 595). Based on the literature review and the empirical results, we formulate recommendations on how to use reversed items in questionnaires.

  8. Ancient Magnetic Reversals: Clues to the Geodynamo.

    Science.gov (United States)

    Hoffman, Kenneth A.

    1988-01-01

    Discusses the question posed by some that the earth's magnetic field may reverse. States that rocks magnetized by ancient fields may offer clues to the underlying reversal mechanism in the earth's core. (TW)

  9. 二阶可逆耦合触发细胞自动机的加密技术研究%Two-order Reversible Couple Toggle Cellular Automata Based Image Encryption Algorithm

    Institute of Scientific and Technical Information of China (English)

    彭川

    2012-01-01

    为了有效改进细胞自动机加密系统的实现复杂度和加解密效率,提出了一种二阶可逆耦合触发细胞自动机的图像加密方法.通过对简单的可逆细胞自动机进行扩展,构造二阶可逆细胞自动机,并以耦合触发规则对明文图像实行分块加密.二阶可逆细胞自动机的转移状态由其当前状态以及前一状态决定,有效增大了邻域范围,并且因为采用耦合触发规则,因此能明显增大加密系统的密钥空间,保证了系统的计算安全性.与一般触发自动机反向迭代的串行加密方式相比,该方法对于每个细胞的加密具有本质并行性,因此具有极高的加解密效率.通过实验验证其性能,结果表明与其它算法相比,该算法具有较大的密钥空间,能够有效抵抗蛮力攻击和差分分析攻击,且较小的邻域半径即可得到良好的加密效果,因此非常便于硬件实现.%To effectively improve the implement complexity and execution efficiency, an algorithm for image encryption is proposed which is based on two-order reversible couple toggle cellular automata (CA). By ways that extending the structure of simple reversible CA (RCA) and adopting couple toggle rules, the algorithm ciphers image which is divided into blocks previously. The CA's state is determined by previous state and next state, so it has larger key space and this can make system safe enough. Compared with general toggle CA (TCA) methods, the algorithm has much better efficiency because each cell is updated parallel Experiments and analysis indicate that this method has an enough large key space, high cipher and decipher speed and good scrambling effect. And the cryptosystem can resist brute attack and differential attack effectively.

  10. An Order Release Control Mechanism Based on self-Adaptive Neural Fuzzy Inference System and Theory of Constraints

    Directory of Open Access Journals (Sweden)

    Chuandong Zhan

    2013-11-01

    Full Text Available Order release is the key premise for the semiconductor wafer fabrication system to perform well, which is also one of the paramount significant components in the scheduling strategies. Most order release strategies merely have focused on the workloadbut failed in considering the remarkable influence oncycletime of common orders that is brought by unexpectedrushones.In this paper an on-linemechanismbased on Theory of Constraintsfor lot releaseusingself-Adaptive Neural Fuzzy Inference System modelswas presentedwhich is able to adjust the release rhythmdynamicallyaccording to dynamics of fabs.In our approach, an ANFIS model was established to predict the ratiobetweenhotand common lotsin wafer fabto perform adjustments on the order release schedule in advance.Simulated experimentsbased on the HP24 model were carefully performed and experimental results proved a better performance of common lotsthan original TOC on a large scale, especially when it comes to the situation of disturbance.  

  11. Calculated third order rate constants for interpreting the mechanisms of hydrolyses of chloroformates, carboxylic Acid halides, sulfonyl chlorides and phosphorochloridates

    National Research Council Canada - National Science Library

    Bentley, T William

    2015-01-01

    .... Third order rate constants (k3) are calculated for solvolytic reactions in a wide range of compositions of acetone-water mixtures, and are shown to be either approximately constant or correlated with the Grunwald-Winstein Y parameter...

  12. Influence of high-order mechanics on simulation of glacier response to climate change: insights from Haig Glacier, Canadian Rocky Mountains

    Directory of Open Access Journals (Sweden)

    S. Adhikari

    2013-04-01

    Full Text Available Evolution of glaciers in response to climate change has mostly been simulated using simplified dynamical models. Because these models do not account for the influence of high-order physics, corresponding results may exhibit some biases. For Haig Glacier in the Canadian Rocky Mountains, we test this hypothesis by comparing simulation results obtained from 3-D numerical models that deal with different assumptions concerning ice-flow physics, ranging from simple shear-deformation to comprehensive Stokes flow. In glacier retreat scenarios, we find a minimal role of high-order mechanics in glacier evolution, as geometric effects at our site (the presence of an overdeepened bed result in limited horizontal movement of ice (flow speed on the order of a few meters per year. Consequently, high-order and reduced models all predict that Haig Glacier ceases to exist by ca. 2080 under ongoing climate warming. The influence of high-order mechanics is evident, however, in glacier advance scenarios, where ice speeds are greater and ice dynamical effects become more important. To generalize these findings for other glacier applications, we advise that high-order mechanics are important and therefore should be considered while modelling the evolution of active glaciers. Reduced model predictions may, however, be adequate for other glaciologic and topographic settings, particularly where flow speeds are low.

  13. Influence of high-order mechanics on simulation of glacier response to climate change: insights from Haig Glacier, Canadian Rocky Mountains

    Directory of Open Access Journals (Sweden)

    S. Adhikari

    2013-09-01

    Full Text Available Evolution of glaciers in response to climate change has mostly been simulated using simplified dynamical models. Because these models do not account for the influence of high-order physics, corresponding results may exhibit some biases. For Haig Glacier in the Canadian Rocky Mountains, we test this hypothesis by comparing simulation results obtained from 3-D numerical models that deal with different assumptions concerning physics, ranging from simple shear deformation to comprehensive Stokes flow. In glacier retreat scenarios, we find a minimal role of high-order mechanics in glacier evolution, as geometric effects at our site (the presence of an overdeepened bed result in limited horizontal movement of ice (flow speed on the order of a few meters per year. Consequently, high-order and reduced models all predict that Haig Glacier ceases to exist by ca. 2080 under ongoing climate warming. The influence of high-order mechanics is evident, however, in glacier advance scenarios, where ice speeds are greater and ice dynamical effects become more important. Although similar studies on other glaciers are essential to generalize such findings, we advise that high-order mechanics are important and therefore should be considered while modeling the evolution of active glaciers. Reduced model predictions may be adequate for other glaciologic and topographic settings, particularly where flow speeds are low and where mass balance changes dominate over ice dynamics in determining glacier geometry.

  14. A review of higher order strain gradient theories of plasticity: Origins, thermodynamics and connections with dislocation mechanics

    Indian Academy of Sciences (India)

    Suman Guha; Sandeep Sangal; Sumit Basu

    2015-06-01

    In this paper we review developments in higher order strain gradient theories. Several variants of these theories have been proposed in order to explain the effects of size on plastic properties that are manifest in several experiments with micron sized metallic structures. It is generally appreciated that the size effect arises from the storage of geometrically necessary dislocations (GNDs) over and above the statistically stored dislocations (SSDs) required for homogeneous deformations. We review developments that show that the GNDs result from the non-homogeneous nature of the deformation field. Though the connection between GNDs and strain gradients are established in the framework of single crystal plasticity, generalisations to polycrystal plasticity has been made. Strain gradient plasticity inherently involves an intrinsic length scale. In our review, we show, through a few illustrative problems, that conventional plasticity solutions can always be reduced to a scale independent form. The same problems are solved with a simple higher order strain gradient formulation to capture the experimentally observed size effects. However, higher order theories need to be thermodynamically consistent. It has recently been shown that only a few of the existing theories pass this test. We review a few that do. Higher order theories require higher order boundary conditions that enable us to model effects of dislocation storage at impermeable boundaries. But these additional boundary conditions also lead to unique conceptual issues that are not encountered in conventional theories. We review attempts at resolving these issues pertaining to higher order boundary conditions. Finally, we review the future of such theories, their relevance and experimental validation.

  15. Modified Decomposition Method with New Inverse Differential Operators for Solving Singular Nonlinear IVPs in First- and Second-Order PDEs Arising in Fluid Mechanics

    Directory of Open Access Journals (Sweden)

    Nemat Dalir

    2014-01-01

    Full Text Available Singular nonlinear initial-value problems (IVPs in first-order and second-order partial differential equations (PDEs arising in fluid mechanics are semianalytically solved. To achieve this, the modified decomposition method (MDM is used in conjunction with some new inverse differential operators. In other words, new inverse differential operators are developed for the MDM and used with the MDM to solve first- and second-order singular nonlinear PDEs. The results of the solutions by the MDM together with new inverse operators are compared with the existing exact analytical solutions. The comparisons show excellent agreement.

  16. Reversible Statistics

    DEFF Research Database (Denmark)

    Tryggestad, Kjell

    2004-01-01

    The study aims is to describe how the inclusion and exclusion of materials and calculative devices construct the boundaries and distinctions between statistical facts and artifacts in economics. My methodological approach is inspired by John Graunt's (1667) Political arithmetic and more recent work...... within constructivism and the field of Science and Technology Studies (STS). The result of this approach is here termed reversible statistics, reconstructing the findings of a statistical study within economics in three different ways. It is argued that all three accounts are quite normal, albeit...... in different ways. The presence and absence of diverse materials, both natural and political, is what distinguishes them from each other. Arguments are presented for a more symmetric relation between the scientific statistical text and the reader. I will argue that a more symmetric relation can be achieved...

  17. Transport Physics in Reversed Shear Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Levinton, F.M.; Batha, S.H. [Fusion Physics and Technology, Inc., Torrance, CA (United States); Beer, M.A.; Bell, M.G.; Budny, R.V.; Efthimion, P.C.; Mazzucato, E.; Nazikian, R.; Park, H.K.; Ramsey, A.T.; Schmidt, G.L.; Scott, S.D.; Synakowski, E.J.; Taylor, G.; Von Goeler, S.; Zarnstorff, M.C. [Princeton University, NJ (United States). Plasma Physics Laboratory; Bush, C.E. [Oak Ridge National Lab., TN (United States)

    1997-12-31

    Reversed magnetic shear is considered a good candidate for improving the tokamak concept because it has the potential to stabilize MHD instabilities and reduce particle and energy transport. With reduced transport the high pressure gradient would generate a strong off-axis bootstrap current and could sustain a hollow current density profile. Such a combination of favorable conditions could lead to an attractive steady-state tokamak configuration. Indeed, a new tokamak confinement regime with reversed magnetic shear has been observed on the Tokamak Fusion Test Reactor (TFTR) where the particle, momentum, and ion thermal diffusivities drop precipitously, by over an order of magnitude. The particle diffusivity drops to the neoclassical level and the ion thermal diffusivity drops to much less than the neoclassical value in the region with reversed shear. This enhanced reversed shear (ERS) confinement mode is characterized by an abrupt transition with a large rate of rise of the density in the reversed shear region during neutral beam injection, resulting in nearly a factor of three increase in the central density to 1.2 X 10(exp 20) cube m. At the same time the density fluctuation level in the reversed shear region dramatically decreases. The ion and electron temperatures, which are about 20 keV and 7 keV respectively, change little during the ERS mode. The transport and transition into and out of the ERS mode have been studied on TFTR with plasma currents in the range 0.9-2.2 MA, with a toroidal magnetic field of 2.7-4.6 T, and the radius of the q(r) minimum, q{sub min}, has been varied from r/a = 0.35 to 0.55. Toroidal field and co/counter neutral beam injection toroidal rotation variations have been used to elucidate the underlying physics of the transition mechanism and power threshold of the ERS mode.

  18. The study of the mechanism of an electrode reaction by first- and second-order techniques A theoretical approach

    NARCIS (Netherlands)

    Sluyters, J.H.; Sluyters-Rehbach, M.; Struys, J.

    1984-01-01

    Abstract The theoretical expressions for the faradaic admittance and the faradaic demodulation voltage are rewritten, introducing the thermodynamic restrictions proposed by Reinmuth in 1972 and without any specification of the mechanism of the electrode reaction. The result is applied to general fi

  19. Lifetimes of organic photovoltaics: Design and synthesis of single oligomer molecules in order to study chemical degradation mechanisms

    DEFF Research Database (Denmark)

    Alstrup, J.; Norrman, K.; Jørgensen, M.

    2006-01-01

    Degradation mechanisms in organic and polymer photovoltaics are addressed through the study of an organic photovoltaic molecule based on a single phenylene-vinylene-type oligomer molecule. The synthesis of such a model compound with different end-groups is presented that allows for assignment...

  20. Simulation studies of nucleation of ferroelectric polarization reversal.

    Energy Technology Data Exchange (ETDEWEB)

    Brennecka, Geoffrey L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Winchester, Benjamin Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-08-01

    Electric field-induced reversal of spontaneous polarization is the defining characteristic of a ferroelectric material, but the process(es) and mechanism(s) associated with the initial nucleation of reverse-polarity domains are poorly understood. This report describes studies carried out using phase field modeling of LiTaO3, a relatively simple prototype ferroelectric material, in order to explore the effects of either mechanical deformation or optically-induced free charges on nucleation and resulting domain configuration during field-induced polarization reversal. Conditions were selected to approximate as closely as feasible those of accompanying experimental work in order to provide not only support for the experimental work but also ensure that additional experimental validation of the simulations could be carried out in the future. Phase field simulations strongly support surface mechanical damage/deformation as effective for dramatically reducing the overall coercive field (Ec) via local field enhancements. Further, optically-nucleated polarization reversal appears to occur via stabilization of latent nuclei via the charge screening effects of free charges.

  1. [Posterior reversible encephalopathy syndrome].

    Science.gov (United States)

    Petrović, Branko; Kostić, Vladimir; Sternić, Nadezda; Kolar, Jovo; Tasić, Nebojsa

    2003-01-01

    Reversible Posterior Leukoencephalopathy Syndrome was introduced into clinical practice in 1996 in order to describe unique syndrome, clinically expressed during hypertensive and uremic encephalopathy, eclampsia and during immunosuppressive therapy [1]. First clinical investigations showed that leucoencephalopathy is major characteristic of the syndrome, but further investigations showed no significant destruction in white cerebral tissue [2, 3, 4]. In majority of cases changes are localise in posterior irrigation area of the brain and in the most severe cases anterior region is also involved. Taking into consideration all above mentioned facts, the suggested term was Posterior Reversible Encephalopathy Syndrome (PRES) for the syndrome clinically expressed by neurological manifestations derived from cortical and subcortical changes localised in posterior regions of cerebral hemispheres, cerebral trunk and cerebellum [5]. Patient, aged 53 years, was re-hospitalized in Cardiovascular Institute "Dediwe" two months after successful aorto-coronary bypass performed in June 2001 due to the chest bone infection. During the treatment of the infection (according to the antibiogram) in September 2001, patient in evening hours developed headache and blurred vision. The recorded blood pressure was 210/120 mmHg so antihypertensive treatment was applied (Nifedipin and Furosemid). After this therapy there was no improvement and intensive headache with fatigue and loss of vision developed. Neurological examination revealed cortical blindness and left hemiparesis. Manitol (20%, 60 ccm every 3 hours) and i.v. Nytroglicerin (high blood pressure). Brain CT revealed oedema of parieto-occipital regions of both hemispheres, more emphasized on the right. (Figure 1a, b, c). There was no sign of focal ischemia even in deeper sections (Figure 1d, e, f). Following three days enormous high blood pressure values were registered. On the fourth day the significant clinical improvement occurred

  2. Simulations of Various Driving Mechanisms for the 3rd Order Resonant Extraction from the MedAustron Medical Synchrotron

    CERN Document Server

    Feldbauer, G; Dorda, U

    2011-01-01

    The MedAustron medical synchrotron is based on the CERN-PIMMS design and its technical implementation by CNAO [1]. This document elaborates on studies performed on the baseline betatron-core driven extraction method and investigates the feasibility of alternative resonance driving mechanisms like RF-knockout, RF-noise and the lattice tune. Single particle tracking results are presented, explained and compared to analytical results.

  3. Ferromagnetism: Sulfur Doping Induces Strong Ferromagnetic Ordering in Graphene: Effect of Concentration and Substitution Mechanism (Adv. Mater. 25/2016).

    Science.gov (United States)

    Tuček, Jiří; Błoński, Piotr; Sofer, Zdeněk; Šimek, Petr; Petr, Martin; Pumera, Martin; Otyepka, Michal; Zbořil, Radek

    2016-07-01

    R. Zbořil and co-workers show that doping a graphene lattice with sulfur induces magnetic centers which display ferromagnetic order below ≈62 K. As described on page 5045, sulfur doping promotes magnetically active configurations resembling the gamma-thiothiapyrone motif. Enhanced magnetic properties of sulfur-doped graphene are attributed to two unpaired electrons from each sulfur atom injected into the graphene conducting band where they are delocalized between the S and C atoms. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Pre-ordering of interfacial water in the pathway of heterogeneous ice nucleation does not lead to a two-step crystallization mechanism

    Science.gov (United States)

    Lupi, Laura; Peters, Baron; Molinero, Valeria

    2016-12-01

    According to Classical Nucleation Theory (CNT), the transition from liquid to crystal occurs in a single activated step with a transition state controlled by the size of the crystal embryo. This picture has been challenged in the last two decades by several reports of two-step crystallization processes in which the liquid first produces pre-ordered or dense domains, within which the crystal nucleates in a second step. Pre-ordering preceding crystal nucleation has been recently reported in simulations of ice crystallization, raising the question of whether the mechanism of ice nucleation involves two steps. In this paper, we investigate the heterogeneous nucleation of ice on carbon surfaces. We use molecular simulations with efficient coarse-grained models combined with rare event sampling methods and free energy calculations to elucidate the role of pre-ordering of liquid water at the carbon surface in the reaction coordinate for heterogeneous nucleation. We find that ice nucleation proceeds through a classical mechanism, with a single barrier between liquid and crystal. The reaction coordinate that determines the crossing of the nucleation barrier is the size of the crystal nucleus, as predicted by CNT. Wetting of the critical ice nuclei within pre-ordered domains decreases the nucleation barrier, increasing the nucleation rates. The preferential pathway for crystallization involves the early creation of pre-ordered domains that are the birthplace of the ice crystallites but do not represent a minimum in the free energy pathway from liquid to ice. We conclude that a preferential pathway through an intermediate-order precursor does not necessarily result in a two-step mechanism.

  5. Single-atom reversible recording at room temperature

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Stokbro, Kurt; Lin, Rong

    2001-01-01

    A single hydrogen atom can be reversibly switched between two symmetric sites on a silicon dimer at the surface of Si(100) using a scanning tunnelling microscope (STM). This is a model binary switch for silicon-based atom-scale reversible data storage at room temperature. In this paper we...... investigate two important aspects of using this single-atom switch as a memory device. First, the switching is electron stimulated, and through detailed modelling the switching probability per electron is accurately deduced. Second, we have investigated the possibilities for desorbing single hydrogen atoms...... to construct ordered arrays of switches to manufacture a memory device. Two desorption mechanisms have been considered: the well known electron-induced desorption at negative sample bias and a novel mechanism probably involving elastic deformation of the tip. For both mechanisms mechanical stability of the STM...

  6. 中国跨国公司逆向知识转移组织机制的实证研究%Empirical study on the organization mechanism of reverse knowledge transfers in mncs of china

    Institute of Scientific and Technical Information of China (English)

    刘明霞; 于飞

    2013-01-01

    Base on knowledge management theory and the sample of MNCs of China,this paper studies the effect of organization mechanism on reverse knowledge transfers from subsidiaries to MNC parents in China by survey and interviews.It is found that cooperation mechanism,communication mechanism and control mechanism affect positively reverse knowledge transfer.But the effect of knowledge management mechanism on reverse knowledge transfer is not significant.This study goes beyond the traditional focus on knowledge characteristics in the past research of knowledge transfer about MNCs,and pay more attention to organization design and mechanism in MNCs' knowledge transfer.This paper enriches the perspectives for research on knowledge transfer in MNCs.%运用知识管理相关理论,以中国跨国公司为研究对象,通过问卷调查和企业访谈,探析了组织机制对中国跨国公司逆向知识转移的影响.研究发现合作式运作结构、沟通机制、控制机制(层级命令、子公司自主权)对逆向知识转移有显著的促进作用,而知识管理机制对逆向知识转移的作用与预期相反且不显著.本文突破了以往跨国公司知识转移研究中只关注知识特性的局限,侧重于知识转移的组织设计和组织机制,丰富了跨国公司知识转移领域的研究视角.

  7. New acoustical technology of sound absorption based on reverse horn

    Science.gov (United States)

    Zhang, Yong Yan; Wu, Jiu Hui; Cao, Song Hua; Cao, Pei; Zhao, Zi Ting

    2016-12-01

    In this paper, a novel reverse horn’s sound-absorption mechanism and acoustic energy focusing mechanism for low-frequency broadband are presented. Due to the alternation of the reverse horn’s thickness, the amplitude of the acoustic pressure propagated in the structure changes, which results in growing energy focused in the edge and in the reverse horn’s tip when the characteristic length is equal to or less than a wavelength and the incident wave is compressed. There are two kinds of methods adopted to realize energy dissipation. On the one hand, sound-absorbing materials are added in incident direction in order to overcome the badness of the reverse horn’s absorption in high frequency and improve the overall high-frequency and low-frequency sound-absorption coefficients; on the other hand, adding mass and film in its tip could result in mechanical energy converting into heat energy due to the coupled vibration of mass and the film. Thus, the reverse horn with film in the tip could realize better sound absorption for low-frequency broadband. These excellent properties could have potential applications in the one-dimensional absorption wedge and for the control of acoustic wave.

  8. Mechanical parameters reverse estimation of lunar soil and experimental verification%月壤力学参数反求及试验验证

    Institute of Scientific and Technical Information of China (English)

    李萌; 高峰; 孙鹏; 崔莹

    2011-01-01

    为了预测月球车的牵引特性并进行牵引控制,提出了一种基于线性最小二乘法的月壤力学参数估计算法,对内聚力和内摩擦角这两个关键的月壤力学参数进行反求.针对反映车轮土壤交互作用过程中轮刺效应的力学模型进行简化,建立了内聚力和内摩擦角的求解模型.将车轮与模拟月壤交互作用试验中的测量数据输入利用该算法编制的Matlab程序中,反求出模拟月壤的内聚力和内摩擦角,反求值与模拟月壤的实测值较为接近.试验验证结果表明该算法准确有效,且具有较好的稳定性和较快的运算速度,可用于月球车进行月壤力学参数的就位估计.%In order to predict and control the traction trafficability of a lunar rover, an algorithm for mechanical parameters estimation of lunar soil based on linear-least squares method was presented to estimate two key mechanical parameters, i. e. , internal cohesion and internal friction angle. The improved wheel-soil interaction model for lugged rigid wheel which considering the effect of wheel lugs on stress distribution was simplified ; An algorithm was thus created to calculate internal cohesion and internal friction angle of the soil. Exper- imental data of wheel-soil interaction were imported into Matlab programs to estimate cohesion and internal friction angle of lunar soil simulant, and the estimated values are close to the measured values of lunar soil stimulant. The results of experimental verification indicate that the algorithm is accurate and effective, moreover, the algorithm also shows good stability and high arithmetic speed, which allows a lunar rover to estimate mechanical parameters of the lunar soil on site.

  9. Mechanism for explaining differences in the order parameters of FeAs-based and FeP-based pnictide superconductors.

    Science.gov (United States)

    Thomale, Ronny; Platt, Christian; Hanke, Werner; Bernevig, B Andrei

    2011-05-01

    We put forward a scenario that explains the difference between the order-parameter character in arsenide (As) and phosphorous (P) iron-based superconductors. Using functional renormalization group to analyze it in detail, we find that nodal superconductivity on the electron pockets (hole pocket gaps are always nodeless) can naturally appear when the hole pocket at (π,π) in the unfolded Brillouin zone is absent, as is the case in LaOFeP. There, electron-electron interactions render the gap on the electron pockets softly nodal (of s(±) form). When the pocket of d(xy) orbital character is present, intraorbital interactions with the d(xy) part of the electron Fermi surface drives the superconductivity nodeless.

  10. Mechanism Study of Gate Leakage Current for AlGaN/GaN High Electron Mobility Transistor Structure Under High Reverse Bias by Thin Surface Barrier Model and Technology Computer Aided Design Simulation

    Science.gov (United States)

    Hayashi, Kazuo; Yamaguchi, Yutaro; Oishi, Toshiyuki; Otsuka, Hiroshi; Yamanaka, Koji; Nakayama, Masatoshi; Miyamoto, Yasuyuki

    2013-04-01

    Gate leakage current mechanism in GaN high electron mobility transistors (HEMTs) has been studied using a two-dimensional thin surface barrier (TSB) model to represent two unintentional donor thin layers that exit under and outside the gate electrode due to the existence of surface defects. The donor thin layer outside the gate affects the reverse gate current at the high gate voltage above the pinch-off voltage. Higher donor concentration of thin layer outside the gate results in larger ratio of lateral to vertical components of the electric field at the gate edge. On the other hand, the electric field at the center of the gate has only the vertical electric field component. As a result, the two-dimensional effects are only important for the reverse gate current above the pinch-off voltage. We have confirmed in this paper that the simulation results provided by our model correlate very well with the experimental reverse gate current characteristics of the device for a very wide range of reverse gate voltage from 0.1 to 90 V.

  11. Study on the Coordinated Operation Mechanism of Reverse Logistics Based on the Internet of Things%基于物联网技术的逆向物流协调运作机制研究

    Institute of Scientific and Technical Information of China (English)

    吴晓晨

    2012-01-01

      Reverse logistics operation has high uncertainty and complexity, the internet of things can solve the information barriers in the process of reverse logistics through the information sharing platform, improve the reverse logistics’ operation efficiency, and ruduce operation cost. In addition, the success of reverse logistics should also make full use of the information sharing platform based on the internet of things to for the mechanisms of decision-making, communication and cooperation.%  逆向物流运作具有更高的不确定性和复杂性,物联网技术通过信息共享平台的建立,能够有效破解逆向物流运作过程中的信息障碍,提高逆向物流的运作效率,降低逆向物流的运作成本。同时,逆向物流的成功运作还应当充分利用物联网信息共享平台建立决策机制、沟通机制和合作机制。

  12. Enantioselective Symmetry Breaking Directed by the Order of Process Steps

    NARCIS (Netherlands)

    Noorduin, Wim L.; Meekes, Hugo; Enckevort, Willem J.P. van; Kaptein, Bernard; Kellogg, Richard M.; Vlieg, Elias

    2010-01-01

    Going forward in reverse: The configuration of the product of grinding-induced symmetry breaking can be controlled simply by the order in which the different reaction-mixture components are combined. The underlying mechanism is based on a subtle balance between enantioselective crystal growth and di

  13. Connecting the grain-shearing mechanism of wave propagation in marine sediments to fractional order wave equations.

    Science.gov (United States)

    Pandey, Vikash; Holm, Sverre

    2016-12-01

    The characteristic time-dependent viscosity of the intergranular pore-fluid in Buckingham's grain-shearing (GS) model [Buckingham, J. Acoust. Soc. Am. 108, 2796-2815 (2000)] is identified as the property of rheopecty. The property corresponds to a rare type of a non-Newtonian fluid in rheology which has largely remained unexplored. The material impulse response function from the GS model is found to be similar to the power-law memory kernel which is inherent in the framework of fractional calculus. The compressional wave equation and the shear wave equation derived from the GS model are shown to take the form of the Kelvin-Voigt fractional-derivative wave equation and the fractional diffusion-wave equation, respectively. Therefore, an analogy is drawn between the dispersion relations obtained from the fractional framework and those from the GS model to establish the equivalence of the respective wave equations. Further, a physical interpretation of the characteristic fractional order present in the wave equations is inferred from the GS model. The overall goal is to show that fractional calculus is not just a mathematical framework which can be used to curve-fit the complex behavior of materials. Rather, it can also be derived from real physical processes as illustrated in this work by the example of GS.

  14. Dynamic origin of segment magnetization reversal in thin-film Penrose tilings

    Science.gov (United States)

    Montoncello, F.; Giovannini, L.; Farmer, B.; De Long, L.

    2017-02-01

    We investigate the low-frequency spin wave dynamics involved in the magnetization reversal of a Penrose P2 tiling using the dynamical matrix method. This system consists of a two-dimensional, connected wire network of elongated thin-film segments, whose complete reversal occurs as a cascade of successive local segment reversals. Using soft mode theory, we interpret the reversal of an individual segment as a first order magnetic transition, in which magnetization curve of the system suffers a small discontinuity. Near this discontinuity a specific mode of the spin wave spectrum goes soft (i.e., its frequency goes to zero), triggering a local instability of the magnetization. We show that this mode is localized, and is at the origin of the local reversal. We discuss the correlation of the mode spatial profile with the ;reversal mechanism;, which is the passage of a domain wall through the segment. This process differs from reversal in periodic square or honeycomb artificial spin ices, where a cascade of reversing segments (e.g., ;Dirac string;) follows an extended (though irregular) path across the sample; here the spatial distribution of successive segment reversals is discontinuous, but strictly associated with the area where a soft mode is localized. The migration of the localization area across the P2 tiling (during reversal in decreasing applied fields) depends on changes in the internal effective field map. We discuss these results in the context of spin wave localization due to the unique topology of the P2 tiling.

  15. Bifunctional Inhibition of Human Immunodeficiency Virus Type 1 Reverse Transcriptase: Mechanism and Proof-of-Concept as a Novel Therapeutic Design Strategy

    Science.gov (United States)

    Bailey, Christopher M.; Sullivan, Todd J.; Iyidogan, Pinar; Tirado-Rives, Julian; Chung, Raymond; Ruiz-Caro, Juliana; Mohamed, Ebrahim; Jorgensen, William; Hunter, Roger; Anderson, Karen S.

    2013-01-01

    Human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT) is a major target for currently approved anti-HIV drugs. These drugs are divided into two classes: nucleoside and non-nucleoside reverse transcriptase inhibitors (NRTIs and NNRTIs). This study illustrates the synthesis and biochemical evaluation of a novel bifunctional RT inhibitor utilizing d4T (NRTI) and a TMC-derivative (a diarylpyrimidine NNRTI) linked via a poly(ethylene glycol) (PEG) linker. HIV-1 RT successfully incorporates the triphosphate of d4T-4PEG-TMC bifunctional inhibitor in a base-specific manner. Moreover, this inhibitor demonstrates low nanomolar potency that has 4.3-fold and 4300-fold enhancement of polymerization inhibition in vitro relative to the parent TMC-derivative and d4T, respectively. This study serves as a proof-of-concept for the development and optimization of bifunctional RT inhibitors as potent inhibitors of HIV-1 viral replication. PMID:23659183

  16. Prolonged reversal of the phencyclidine-induced impairment in novel object recognition by a serotonin (5-HT)1A-dependent mechanism.

    Science.gov (United States)

    Horiguchi, Masakuni; Miyauchi, Masanori; Neugebauer, Nichole M; Oyamada, Yoshihiro; Meltzer, Herbert Y

    2016-03-15

    Many acute treatments transiently reverse the deficit in novel object recognition (NOR) produced by subchronic treatment with the N-methyl-d-aspartate receptor non-competitive antagonist, phencyclidine (PCP), in rodents. Treatments which restore NOR for prolonged periods after subchronic PCP treatment may have greater relevance for treating the cognitive impairment in schizophrenia than those which restore NOR transiently. We examined the ability of post-PCP subchronic lurasidone, an atypical APD with potent serotonin (5-HT)1A partial agonism and subchronic tandospirone, a selective 5-HT1A partial agonist, to enable prolonged reversal of the subchronic PCP-induced NOR deficit. Rats treated with subchronic PCP (2mg/kg, twice daily for 7 days) or vehicle, followed by a 7day washout period were subsequently administered lurasidone or tandospirone twice daily for 7 days (day 15-21), and tested for NOR weekly for up to two additional weeks. Subchronic lurasidone (1, but not 0.1mg/kg) or tandospirone (5, but not 0.6mg/kg) significantly reversed the PCP-induced NOR deficit at 24h and 7days after the last injection, respectively. The effect of lurasidone persisted for one more week (day 36, 14 days after the last lurasidone dose), while tandospirone-treated rats were able to perform NOR at 7, but not 14, days after the last tandospirone dose. Co-administration of WAY100635 (0.6mg/kg), a 5-HT1A antagonist, with lurasidone, blocked the ability of lurasidone to restore NOR, suggesting that 5-HT1A receptor stimulation is necessary for lurasidone to reverse the effects of PCP. The role of dopamine, GABA and the MAPK/ERK signalling pathway in the persistent, but not indefinite, restoration of NOR is discussed.

  17. studies in the relationship between molecular structure and chromatographic behaviour-III Mechanism of the reversed-phase chromatography of some alkyl phenols.

    Science.gov (United States)

    Bark, L S; Graham, R J

    1966-09-01

    It can be shown that thin-layer chromatography by the reversed-phase technique gives results which are sufficiently reproducible for correlation of Chromatographie behaviour with chemical structure to be attempted. To a first approximation the Martin additivity principle is valid, but variations in the intermolecular forces between solute molecules and solvent molecules, caused by the easy transmission of electronic effects through an aromatic system, result in deviations from ideal conditions.

  18. The NMR solution structure of a mutant of the Max b/HLH/LZ free of DNA: insights into the specific and reversible DNA binding mechanism of dimeric transcription factors.

    Science.gov (United States)

    Sauvé, Simon; Tremblay, Luc; Lavigne, Pierre

    2004-09-17

    Basic region-helix1-loop-helix2-leucine zipper (b/H(1)LH(2)/LZ) transcription factors bind specific DNA sequence in their target gene promoters as dimers. Max, a b/H(1)LH(2)/LZ transcription factor, is the obligate heterodimeric partner of the related b/H(1)LH(2)/LZ proteins of the Myc and Mad families. These heterodimers specifically bind E-box DNA sequence (CACGTG) to activate (e.g. c-Myc/Max) and repress (e.g. Mad1/Max) transcription. Max can also homodimerize and bind E-box sequences in c-Myc target gene promoters. While the X-ray structure of the Max b/H(1)LH(2)/LZ/DNA complex and that of others have been reported, the precise sequence of events leading to the reversible and specific binding of these important transcription factors is still largely unknown. In order to provide insights into the DNA binding mechanism, we have solved the NMR solution structure of a covalently homodimerized version of a Max b/H(1)LH(2)/LZ protein with two stabilizing mutations in the LZ, and characterized its backbone dynamics from (15)N spin-relaxation measurements in the absence of DNA. Apart from minor differences in the pitch of the LZ, possibly resulting from the mutations in the construct, we observe that the packing of the helices in the H(1)LH(2) domain is almost identical to that of the two crystal structures, indicating that no important conformational change in these helices occurs upon DNA binding. Conversely to the crystal structures of the DNA complexes, the first 14 residues of the basic region are found to be mostly unfolded while the loop is observed to be flexible. This indicates that these domains undergo conformational changes upon DNA binding. On the other hand, we find the last four residues of the basic region form a persistent helical turn contiguous to H(1). In addition, we provide evidence of the existence of internal motions in the backbone of H(1) that are of larger amplitude and longer time-scale (nanoseconds) than the ones in the H(2) and LZ domain

  19. Adsorption mechanism of acids and bases in reversed-phase liquid chromatography in weak buffered mobile phases designed for liquid chromatography/mass spectrometry.

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2009-03-06

    The overloaded band profiles of five acido-basic compounds were measured, using weakly buffered mobile phases. Low buffer concentrations were selected to provide a better understanding of the band profiles recorded in LC/MS analyses, which are often carried out at low buffer concentrations. In this work, 10 microL samples of a 50 mM probe solution were injected into C(18)-bonded columns using a series of five buffered mobile phases at (SW)pH between 2 and 12. The retention times and the shapes of the bands were analyzed based on thermodynamic arguments. A new adsorption model that takes into account the simultaneous adsorption of the acidic and the basic species onto the endcapped adsorbent, predicts accurately the complex experimental profiles recorded. The adsorption mechanism of acido-basic compounds onto RPLC phases seems to be consistent with the following microscopic model. No matter whether the acid or the base is the neutral or the basic species, the neutral species adsorbs onto a large number of weak adsorption sites (their saturation capacity is several tens g/L and their equilibrium constant of the order of 0.1 L/g). In contrast, the ionic species adsorbs strongly onto fewer active sites (their saturation capacity is about 1g/L and their equilibrium constant of the order of a few L/g). From a microscopic point of view and in agreement with the adsorption isotherm of the compound measured by frontal analysis (FA) and with the results of Monte-Carlo calculations performed by Schure et al., the first type of adsorption sites are most likely located in between C(18)-bonded chains and the second type of adsorption sites are located deeper in contact with the silica surface. The injected concentration (50 mM) was too low to probe the weakest adsorption sites (saturation capacity of a few hundreds g/L with an equilibrium constant of one hundredth of L/g) that are located at the very interface between the C(18)-bonded layer and the bulk phase.

  20. 基于逆向工程技术圆柱凸轮机构的CAD/CAM%CAD/CAM of cylindrical cam mechanism based on re-verse engineering technology

    Institute of Scientific and Technical Information of China (English)

    蒋萌; 葛正浩; 屈毅; 李艳妮

    2011-01-01

    The papeer presents a new process and method of revere design and manufacturing of the cylindrical cam mechanism.By applying the Coordinate Measuring Machine (CMM) and the PRO/E software as the platform to carry out aided design, by taking Microsoft Visual C + + 6.0 as the development tool, and based on Windows platform, the cylindrical cam mechanism dealgn and manufacturing software is generated, allowing the design of cycle map and cam profile, checking the pressure angle and curvature radius rapidly, almulating the motion of cam. And the NC machining codes which can be directly used for numerical control machine were generated, achieviug the integration of design and manufacture of cylindrical cam mechanism. This CAD/CAM system can not only be applied in the reverse design of cylindrical cam mechanism, but alao used to achieve the forward de-sign of cylindrical ,cam mechanism quickly and easily. Finally, by taking reverse, design and manufacture of the cylindrical indexing cam as an example, the reverse design and manufacturing process and method of cylindrical cam mechanism based on reverse engineering technology has been explained in detail.%介绍了圆柱凸轮机构逆向设计与制造的流程和方法.利用三坐标测量机和Pro/E软件为平台实现辅助设计,以Microsolft Visual C++6.0为开发工具,基于Windows平台编制了圆柱凸轮机构设计与制造软件,实现了圆柱凸轮机构的循环图和轮廓设计,并可进行压力角及曲率半径的快速校核和凸轮的运动仿真,生成了直接用于数控机床的刀具NC加工代码,实现了圆柱凸轮机构设计制造一体化.此CAD/CAM系统不仅可用于圆柱凸轮机构的反求设计,亦可简单快捷地实现圆柱凸轮机构的正向设计.文中以圆柱分度凸轮的反求与制造为例详细说明了基于逆向工程技术圆柱凸轮机构的设计与制造方法和流程.

  1. 低碳经济背景下发展逆向物流的理论基础与保障机制研究%The Study on the Theoretical Foundation of Reverse Logistics and Its Safeguard Mechanism in the Context of Low-carbon Economy

    Institute of Scientific and Technical Information of China (English)

    郝书池; 姜燕宁

    2011-01-01

    发展逆向物流是实现低碳经济的重要手段,利益相关者理论、博弈理论、可持续发展理论、循环经济理论、外部性理论和生态经济学理论都是其坚实的理论基础。现阶段逆向物流的发展存在认识不够、法律法规不健全、技术水平低、供需不确定性大和网络不健全的问题,严重阻碍了逆向物流的发展。建立包括政府、企业、公民共同参与,法律法规健全,技术先进和激励措施高效在内的保障机制,推动逆向物流的健康有序发展。%Developing reverse logistics is an important means to achieve low-carbon economy, and stakeholder theory, game theory, sustainable development theory, recycling economy theory, externality theory and ecological economics are its solid theoretical foundation. At this stage the problems in the development of reverse logistics include inadequate laws and regulations, low level of technology, uncertainty of supply and demand and inadequate network, which seriously hindered the development of reverse logistics. Safeguard mechanisms including government, business and citizen participation, adequate laws and regulations, advanced technologies, and efficient incentive measures should be established to promote the healthy and orderly development of reverse logistics.

  2. Mechanism and Model Construction of Compression Set Reversible Rrecovery of HIPS/HVPBR Thermoplastic Vulcanizate%HIPS/HVPBR热塑性硫化胶压缩永久变形可逆回复的模型及机制

    Institute of Scientific and Technical Information of China (English)

    赵静; 华静; 王兆波

    2014-01-01

    采用动态硫化法制备了高抗冲聚苯乙烯(HIPS)/高乙烯基聚丁二烯(HVPBR)热塑性硫化胶(TPV),研究了橡塑比和热处理温度对压缩永久变形可逆回复的影响,探讨了可逆回复机制并构建了数学模型。结果表明,提高橡塑比和热处理温度,压缩永久变形的可逆回复程度和回复速度明显提高;热处理温度接近基体Tg 时,体系的压缩永久变形几乎完全可逆;基于可逆回复过程,探讨压缩永久变形的可逆回复机制,并构建了其数学模型,进而探讨了橡塑比和热处理温度对可逆回复各阶段松弛时间的影响。%Thermoplastic vulcanizate (TPV)based on high impact polystyrene (HIPS)/high vinyl polybutadiene rubber (HVPBR)blends were prepared by dynamic vulcanization,and the influences of blending ratio and heat-treatment temperature on the reversible recovery of compression set,together with the mechanism and model construction of the reversible recovery of the TPV,were investigated systematically.The results showed that increasing the content of HVPBR in TPV and increasing heat-treatment temperature would lead to the fast recovery of compression set;moreover,the TPV had fully reversible deformation ability when the heat-treatment temperature was close to the Tg of HIPS. The reversible recovery mechanism was discussed based on the characteristics of the reversible recov-ery curves of compression set.A mathematical model to explain the reversible recovery of compression set was established via the fitting of the experimental data,and the influences of blending ratio and heat-treatment temperature on the relaxation time in each stage of the recovery course were discussed.

  3. Fractionalization of the complex-valued Brownian motion of order n using Riemann-Liouville derivative. Applications to mathematical finance and stochastic mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Jumarie, Guy [Department of Mathematics, University of Quebec at Montreal, P.O. Box 8888, Downtown Station, Montreal, QC, H3C 3P8 (Canada)]. E-mail: jumarie.guy@uqam.ca

    2006-06-15

    The (complex-valued) Brownian motion of order n is defined as the limit of a random walk on the complex roots of the unity. Real-valued fractional noises are obtained as fractional derivatives of the Gaussian white noise (or order two). Here one combines these two approaches and one considers the new class of fractional noises obtained as fractional derivative of the complex-valued Brownian motion of order n. The key of the approach is the relation between differential and fractional differential provided by the fractional Taylor's series of analytic function f(z+h)=E{sub {alpha}}(h{sup {alpha}}D{sub z}{sup {alpha}}).f(z), where E{sub {alpha}} is the Mittag-Leffler function on the one hand, and the generalized Maruyama's notation, on the other hand. Some questions are revisited such as the definition of fractional Brownian motion as integral w.r.t. (dt){sup {alpha}}, and the exponential growth equation driven by fractional Brownian motion, to which a new solution is proposed. As a first illustrative example of application, in mathematical finance, one proposes a new approach to the optimal management of a stochastic portfolio of fractional order via the Lagrange variational technique applied to the state moment dynamical equations. In the second example, one deals with non-random Lagrangian mechanics of fractional order. The last example proposes a new approach to fractional stochastic mechanics, and the solution so obtained gives rise to the question as to whether physical systems would not have their own internal random times.

  4. Analysis of cryptographic mechanisms used in ransomware CryptXXX v3

    Directory of Open Access Journals (Sweden)

    Michał Glet

    2016-12-01

    Full Text Available The main purpose of this paper was to analysis how malicious software is using cryptographic mechanisms. Reverse engineering were applied in order to discover mechanisms used in ransomware CryptXXX v3. At the end were given some useful advices how to improve CryptXXX.[b]Keyword:[/b] ransomware, software engineering, reverse engineering, RC4, RSA, malicious software

  5. Analysis of cryptographic mechanisms used in ransomware CryptXXX v3

    OpenAIRE

    Michał Glet

    2016-01-01

    The main purpose of this paper was to analysis how malicious software is using cryptographic mechanisms. Reverse engineering were applied in order to discover mechanisms used in ransomware CryptXXX v3. At the end were given some useful advices how to improve CryptXXX.[b]Keyword:[/b] ransomware, software engineering, reverse engineering, RC4, RSA, malicious software

  6. Mechanism to generate a two-dimensional electron gas at the surface of the charge-ordered semiconductor BaBiO3.

    Science.gov (United States)

    Vildosola, Verónica; Güller, Francisco; Llois, Ana María

    2013-05-17

    In this Letter, we find by means of first-principles calculations a new physical mechanism to generate a two-dimensional electron gas, namely, the breaking of charge ordering at the surface of a charge-ordered semiconductor due to the incomplete oxygen environment of the surface ions. The emergence of the 2D gas is independent of the presence of oxygen vacancies or polar discontinuities; this is a self-doping effect. This mechanism might apply to many charge-ordered systems, in particular, we study the case of BaBiO(3)(001). Our calculations show that the outer layer of the Bi-terminated simulated surface turns more cubiclike and metallic while the inner layers remain in the insulating monoclinic state that the system present in the bulk form. On the other hand, the metallization does not occur for the Ba termination, a fact that makes this system appealing for nanostructuring. Finally, in view of the bulk properties of this material under doping, this particular finding sets another possible route for future exploration: the potential scenario of 2D superconductivity at the BaBiO(3) surface.

  7. Multiple resonant coupling mechanism for suppression of higher-order modes in all-solid photonic bandgap fibers with heterostructured cladding.

    Science.gov (United States)

    Murao, Tadashi; Saitoh, Kunimasa; Koshiba, Masanori

    2011-01-31

    In this paper, we propose a novel mechanism for suppression of higher-order modes (HOMs), namely multiple resonant coupling, in all-solid photonic bandgap fibers (PBGFs) with effectively large core diameters. In an analogy to the well-known tight-binding theory in solid-state physics, multiple anti-resonant reflecting optical waveguide (ARROW) modes bound in designedly arranged defects in the cladding make up Bloch states and resultant photonic bands with a finite effective-index width, which contribute to the suppression of HOMs. In particular, contrary to the conventional method for the HOM suppression using the index-matching of the HOMs in the core of the PBGF and the defect mode arranged in the cladding, the proposed mechanism guarantees a broadband HOM suppression without a precise structural design. This effect is explained by the multiple resonant coupling, as well as an enhanced confinement loss mechanism which occurs near the condition satisfying the multiple resonant coupling. Moreover, we show that the proposed structure exhibits a lower bending loss characteristic when compared to the conventional all-solid PBGFs. The simultaneous realization of the single-mode operation and the low bending loss property is due to the novel cladding concept named as heterostructured cladding. The proposed structure also resolves the issue for the increased confinement loss property in the first-order photonic bandgap (PBG) at the same time.

  8. Designing the Reverse Supply Chain

    DEFF Research Database (Denmark)

    Gobbi, Chiara

    2011-01-01

    for the reverse supply chain. Design/methodology/approach – In order to identify the relevance of the Fisher model, the model needs to be recast in terms of PRV, which, in this context, is considered the independent variable in the reverse logistics arena. Products defined as innovative in Fisher's taxonomy...... is associated with first-class recovery options (reconditioning and remarketing). When the recovery option is recycling, time is not relevant, the primary objective is cost reduction (efficiency), the chain is centralized, and actors and phases of the reverse chain are determined by the specificity...... of the recycling process. When the recovery option is reconditioning, time is primarily relevant, tradeoffs between costs and time efficiency are necessary, the chain presents a centralized structure, and the presence of other types of actors and phases influences the structure of the reverse supply chain...

  9. Towards a reversible functional language

    DEFF Research Database (Denmark)

    Yokoyama, Tetsuo; Axelsen, Holger Bock; Glück, Robert

    2012-01-01

    first-match policy for case expressions, we can write overlapping patterns in case branches, as is customary in ordinary functional languages, and also in leaf expressions, unlike existing inverse interpreter methods, which enables concise programs. In patterns, the use of a duplication......We identify concepts of reversibility for a functional language by means of a set of semantic rules with specific properties. These properties include injectivity along with local backward determinism, an important operational property for an efficient reversible language. We define a concise...... reversible first-order functional language in which access to the backward semantics is provided to the programmer by inverse function calls. Reversibility guarantees that in this language a backward run (inverse interpretation) is as fast as the corresponding forward run itself. By adopting a symmetric...

  10. Reversible Switching of Cooperating Replicators

    Science.gov (United States)

    Urtel, Georg C.; Rind, Thomas; Braun, Dieter

    2017-02-01

    How can molecules with short lifetimes preserve their information over millions of years? For evolution to occur, information-carrying molecules have to replicate before they degrade. Our experiments reveal a robust, reversible cooperation mechanism in oligonucleotide replication. Two inherently slow replicating hairpin molecules can transfer their information to fast crossbreed replicators that outgrow the hairpins. The reverse is also possible. When one replication initiation site is missing, single hairpins reemerge from the crossbreed. With this mechanism, interacting replicators can switch between the hairpin and crossbreed mode, revealing a flexible adaptation to different boundary conditions.

  11. Pathophysiology of reversible sudden deafness--epidemiological study.

    Directory of Open Access Journals (Sweden)

    Ohsaki,Katsuichiro

    1983-04-01

    Full Text Available Many aspects of the etiology and pathophysiology of reversible sudden deafness remain obscure. In order to better understand the pathophysiology of reversible sudden deafness we compared the results of two therapies which have different mechanisms of action. The results of therapy with tranexamic acid alone in 49 cases (57 ears of sudden deafness were compared with the results of treatment with so-called antisludging agents in 65 cases (69 ears using the chi square contingency test. The same therapeutic effect was observed in both groups despite the different modes of chemical action of the two therapeutics. A series of processes involving an increase in permeability of vascular walls and related edema, and extravascular red cell oozing due to hypoxia or anoxia leading to tissue damage in the inner ear seem to be important factors in the etiology and pathophysiology of reversible sudden deafness.

  12. Study of the Activity and Possible Mechanism of Action of a Reversible Inhibitor of Recombinant Human KAT-2: A Promising Lead in Neurodegenerative and Cognitive Disorders

    Directory of Open Access Journals (Sweden)

    Alireza Nematollahi

    2016-06-01

    Full Text Available Abnormal levels of kynurenic acid (KYNA in the human brain are believed to be connected to several central nervous system (CNS diseases, therefore compounds which affect the production of this crucial metabolite are of interest in CNS drug development. The majority of KYNA production is accounted for by kynurenine aminotransferase-2 (KAT-2 in the mammalian brain; hence this enzyme is one of the most interesting targets with which to modulate KYNA levels. Recently developed human KAT-2 inhibitors with high potencies are known to irreversibly bind to the enzyme cofactor, pyridoxal-5′-phosphate (PLP, which may lead to severe side effects due to the abundance of PLP-dependent enzymes. In this study, we report a reversible and competitive inhibitor of KAT-2. Its inhibitory activities were examined using HPLC and surface plasmon resonance (SPR and compare favorably with other recently reported KAT-2 inhibitors. Our inhibitor, NS-1502, demonstrates suitable inhibitory activity, almost 10 times more potent than the known reversible KAT-2, (S-ESBA.

  13. Senescence in hepatic stellate cells as a mechanism of liver fibrosis reversal: a putative synergy between retinoic acid and PPAR-gamma signalings.

    Science.gov (United States)

    Panebianco, Concetta; Oben, Jude A; Vinciguerra, Manlio; Pazienza, Valerio

    2017-08-01

    Hepatic stellate cells (HSCs), also known as perisinusoidal cells, are pericytes found in the perisinusoidal space of the liver. HSCs are the major cell type involved in liver fibrosis, which is the formation of scar tissue in response to liver damage. When the liver is damaged, stellate cells can shift into an activated state, characterized by proliferation, contractility and chemotaxis. The activated HSCs secrete collagen scar tissue, which can lead to cirrhosis. Recent studies have shown that in vivo activation of HSCs by fibrogenic agents can eventually lead to senescence of these cells, which would contribute to reversal of fibrosis although it may also favor the insurgence of liver cancer. HSCs in their non-active form store huge amounts of retinoic acid derivatives in lipid droplets, which are progressively depleted upon cell activation in injured liver. Retinoic acid is a metabolite of vitamin A (retinol) that mediates the functions of vitamin A, generally required for growth and development. The precise function of retinoic acid and its alterations in HSCs has yet to be elucidated, and nonetheless in various cell types retinoic acid and its receptors (RAR and RXR) are known to act synergistically with peroxisome proliferator-activated receptor gamma (PPAR-gamma) signaling through the activity of transcriptional heterodimers. Here, we review the recent advancements in the understanding of how retinoic acid signaling modulates the fibrogenic potential of HSCs and proposes a synergistic combined action with PPAR-gamma in the reversal of liver fibrosis.

  14. Reversal effect of sulpiride on rotational behaviour of rats with unilateral frontal cortex ablation: an alternative explanation for the pharmacological mechanism of its antidepressant effect.

    Science.gov (United States)

    Kaneno, S; Fukamauchi, F; Komatsu, H; Koyama, K; Ikawa, K

    2001-02-01

    The antidepressant effect of sulpiride has been generally explained as the result of its preferential blocking effect on self-inhibitory presynaptic dopamine autoreceptors at low doses. Low dose haloperidol has the same blocking effect. In rats with unilateral ablation of the frontal cortex, methamphetamine administration induced mild contralateral rotation 10 days after the operation. We examined whether low dose sulpiride and haloperidol would have the same effect on this rotational model. High dose sulpiride (100 mg/kg) or low dose haloperidol (0.05 mg/kg) prevented this methamphetamine-induced rotation. However, low dose (15 mg/kg) sulpiride clearly reversed the direction of rotation. This reversal effect of low dose sulpiride is not explained by the preferential blocking effect on dopamine autoreceptors. The results suggest that low dose sulpiride, unlike low dose haloperidol, has a prominent blocking effect on D2 receptors in the frontal cortex. This unique effect of sulpiride may be relevant to its clinical antidepressant and anxiolytic effects at low doses.

  15. 基于高阶逻辑的双基融合机制%Double-Bases Cooperating Mechanism Based on Higher-Order Logic

    Institute of Scientific and Technical Information of China (English)

    刘英华; 李广原; 刘永彬; 郭建威

    2011-01-01

    随着知识库规模的扩大及结构的日趋复杂,一阶逻辑表达能力有限的问题暴露得越来越严重,基于高阶逻辑的知识表示显得尤为必要.原有基于KDK和KDK*的研究必然导致向高阶逻辑研究的拓展.首先概述了基于知识库的知识发现,然后介绍了高阶逻辑知识表示语言Escher、双基融合机制KDK和KDK*,最后在高阶逻辑背景下,扩展双基融合机制的内涵,给出了面向高阶逻辑的KDK*过程模型逻辑等价定理.%With expanding of the knowledge base scale and increasingly complication of its structure,the problems of the limited capability of first-order logic expose to be more and more serious,thus the application that based on knowledge representation of higher-order logic is quite necessary.The original research based on KDK and KDK* will inevitably lead to development and research of higher first-order logic.This paper first summarizes the knowledge discovery that based on the knowledge base,then introduces the representation language of the high-order logic knowledge-Escher,KDK and KDK*.At last,expands the connotation of Double-Bases Cooperating Mechanism under the background of first-order logic,and illustrate the equivalence theorem of KDK* process model logic that is facing the high-order logic.

  16. Effects of Ni vacancy, Ni antisite, Cr and Pt on the third-order elastic constants and mechanical properties of NiAl

    KAUST Repository

    Wu, Shaohua

    2014-12-01

    Effects of Ni vacancy, Ni antisite in Al sublattice, Cr in Al sublattice, Pt in Ni sublattice on the second-order elastic constants (SOECs) and third-order elastic constants (TOECs) of the B2 NiAl have been investigated using the first-principles methods. Lattice constant and the SOECs of NiAl are in good agreement with the previous results. The brittle/ductile transition map based on Pugh ratio G/B and Cauchy pressure Pc shows that Ni antisite, Cr, Pt and pressure can improve the ductility of NiAl, respectively. Ni vacancy and lower pressure can enhance the Vickers hardness Hv of NiAl. The density of states (DOS) and the charge density difference are also used to analysis the effects of vacancy, Ni antisite, Cr and Pt on the mechanical properties of NiAl, and the results are in consistent with the transition map. © 2014 Elsevier Ltd. All rights reserved.

  17. Effect of growth mechanisms on the deformation of a unit cell and polarization reversal in barium-strontium titanate heterostructures on magnesium oxide

    Science.gov (United States)

    Mukhortov, V. M.; Golovko, Yu. I.; Biryukov, S. V.; Anokhin, A.; Yuzyuk, Yu. I.

    2016-01-01

    The effect of a growth mechanism on the unit cell strain and the related change in the properties of single-crystal Ba0.8Sr0.2TiO3 films grown on MgO substrates according to the Frank-van der Merwe and Volmer-Weber growth mechanisms is studied. The unit cell strain is shown to depend substantially on the film thickness and the growth mechanism. It is found that the same film-substrate pair can be used to vary stresses in the film from two-dimensional tensile to compressive stresses due to a change in the growth mechanism and the film thickness.

  18. Study on the coherence degree of magnetization reversal in Permalloy single-domain nano-ellipses

    Science.gov (United States)

    Júnior, D. S. Vieira; Leonel, S. A.; Toscano, D.; Sato, F.; Coura, P. Z.; Dias, R. A.

    2017-03-01

    Numerical simulations have been performed to study the magnetization reversal in Permalloy nano-ellipses, under combined in-plane magnetic fields along the longitudinal and the transverse directions. We have considered nano-ellipses with two different aspect ratios and five thicknesses: 220×80×t nm3 and 70×50×t nm3, where t ranging from 5 to 25 nm in steps of 5 nm. We found that the mechanism of magnetization reversal is not only dependent on the parameters of the magnetic field pulse but also related to the ellipse dimensions. It is known that the reversal time is related to the mechanism behind the magnetization reversal. In particular, ultrafast magnetization reversals occur by coherent rotation, when applying a field oriented mainly perpendicular to the initial magnetization. In order to evaluate the degree of coherence of the magnetization reversal we have introduced a quantity called "coherence index". Besides complementing the previous studies by including the effect of the thickness on the magnetization reversal, our results indicate that it is possible to obtain magnetization reversals with high degree of coherence in small nano-ellipses by adjusting the geometric factors of the ellipse and the parameters of the magnetic field pulse simultaneously.

  19. Global species richness patterns and their drivers among the order Anseriformes

    DEFF Research Database (Denmark)

    Dalby, Lars; McGill, Brian J.; Fox, Anthony David;

    2012-01-01

    Birds (class Aves) follow the latitudinal gradient in species richness (more species are found closer to the tropics). However lowering the taxonomic scale to orders other patterns can emerge which can be instructive about mechanism. For example, in the order Anseriformes the pattern is reversed ......, especially on a global scale where the strength of the predictors are likely change....

  20. The mechanism of paramagnetic NMR relaxation produced by Mn(II): role of orthorhombic and fourth-order zero field splitting terms.

    Science.gov (United States)

    Sharp, Robert

    2008-10-14

    Mn(II) is a spin-5/2 paramagnetic ion that mediates a characteristically large NMR paramagnetic relaxation enhancement (NMR-PRE) of nuclear spins in solution. In the range of high magnetic field strengths (above about 0.3 T), where the electronic Zeeman interaction provides the largest term of the electron spin Hamiltonian, NMR relaxation mechanism is well understood. In the lower field range, the physical picture is more complex because of the presence in the spin Hamiltonian of zero field splitting (ZFS) terms that are comparable to or greater than the Zeeman term. This work describes a systematic study of the relaxation mechanism in the low field range, particularly aspects involving the dependence of NMR-PRE on the orthorhombic (E) and fourth-order (a(q)(4), q=0,2,4) ZFS tensor components. It is shown that the fourfold (a(4)(4)) and twofold (a(2)(4)) fourth-order components exert large orientation-dependent influences on the NMR-PRE. Thus, fourth-order terms with magnitudes equal to only a few percent of the quadratic ZFS terms (D,E) produce large changes in the shape of the magnetic field profile of the PRE. Effects arising from the orthorhombic quadratic ZFS term (E) are much smaller than those of the fourth-order terms and can in most cases be neglected. However, effects due to a(4)(4) and a(2)(4) need to be included in simulations of low field data.

  1. Nonlinear and chaos control of a micro-electro-mechanical system by using second-order fast terminal sliding mode control

    Science.gov (United States)

    Zhankui, Song; Sun, Kaibiao

    2013-09-01

    In this paper, a novel second-order fast terminal sliding mode control (SFTSMC) scheme is proposed to suppress the chaotic motion of a micro-mechanical resonator with system uncertainty and external disturbance. To obtain a better disturbance rejection property, a fuzzy logic system is introduced to estimate the upper boundary of the sum of system uncertainty and external disturbance. Moreover, we employ the finite-time technique to obtain the properties of fast response and high precision. Finally, numerical simulations demonstrate the effectiveness of the proposed control scheme.

  2. Evidence of stress-induced hydrogen ordering in zirconium hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Steuwer, A. [FaME38 at the ESRF-ILL, 6 rue J Horowitz, 38042 Grenoble (France); ESS Scandinavia, University of Lund, Stora Algatan 4, 22350 Lund (Sweden)], E-mail: steuwer@ill.fr; Santisteban, J.R. [Centro Atomico Bariloche, CNEA, San Carlos de Bariloche (Argentina); Preuss, M. [University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom); Peel, M.J.; Buslaps, T. [European Synchrotron Radiation Facility, 6 rue J Horowitz, 38042 Grenoble (France); Harada, M. [R and D Section, Chofu-Kita Plant, Kobe Special Tube Co, Shimonoseki 752-0953 (Japan)

    2009-01-15

    The formation of hydrides in zirconium alloys significantly affects their mechanical properties and is considered to play a critical role in their failure mechanisms, yet relatively little is known about the micromechanical behavior of hydrides in the bulk. This paper presents the result of in situ uniaxial mechanical tensioning experiments on hydrided zircaloy-2 and zircaloy-4 specimens using energy-dispersive synchrotron X-ray diffraction, which suggests that a stress-induced transformation of the {delta}-hydride to {gamma}-hydride via ordering of the hydrogen atoms occurs, akin to a Snoek-type relaxation. Subsequent annealing was found to reverse the ordering phenomenon.

  3. Reversibly Bistable Flexible Electronics

    KAUST Repository

    Alfaraj, Nasir

    2015-05-01

    Introducing the notion of transformational silicon electronics has paved the way for integrating various applications with silicon-based, modern, high-performance electronic circuits that are mechanically flexible and optically semitransparent. While maintaining large-scale production and prototyping rapidity, this flexible and translucent scheme demonstrates the potential to transform conventionally stiff electronic devices into thin and foldable ones without compromising long-term performance and reliability. In this work, we report on the fabrication and characterization of reversibly bistable flexible electronic switches that utilize flexible n-channel metal-oxide-semiconductor field-effect transistors. The transistors are fabricated initially on rigid (100) silicon substrates before they are peeled off. They can be used to control flexible batches of light-emitting diodes, demonstrating both the relative ease of scaling at minimum cost and maximum reliability and the feasibility of integration. The peeled-off silicon fabric is about 25 µm thick. The fabricated devices are transferred to a reversibly bistable flexible platform through which, for example, a flexible smartphone can be wrapped around a user’s wrist and can also be set back to its original mechanical position. Buckling and cyclic bending of such host platforms brings a completely new dimension to the development of flexible electronics, especially rollable displays.

  4. Mechanism of drug resistance and reversal with ligustra-zine and cyclosporin A in cisplatin-induced human epithelial ovarian cancer resistant cell line 3Ao/cDDP

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective: To investigate the mechanism of resistance and reversal effect of ligustrazine and cyclosporin A in cisplatin-induced multidrug resistance ovarian cancer cell line 3Ao/cDDP. Methods: Using the corresponding dose calculated from clinical chemotherapy at 30 mg cisplatin per cycle, we established 3Ao/cDDP with 3Ao exposed at regular intervals and repeatedly to high-level concentration of cisplatin at 10 m g/ml for 24 hours each time. Expressions of LRP, MRP, P-gp, GSTp and TopoII were quantitatively detected with FCM. For drug resistance reversal, cyclosporin A and ligustrazine were administered singly or in combination at the maximal dose without cytotoxicity. Inhibition rates were determined by MTT assay. Results: 3Ao/cDDP was established after 4.5 months, with resistance factor 1.6 which was similar to clinical resistance degree. Low expression levels of MRP and P-gp were found in both 3Ao and 3Ao/cDDP (P>0.05), and LRP and GSTp expression levels in 3Ao/cDDP were significantly higher than those in 3Ao (P0.05 vs cDDP), cDDP plus cyclosporin A 49.635± 0.021% (P<0.01 vs cDDP), and cDDP plus ligustrazine and cyclosporin A 58.861± 0.014% (P<0.01 vs cDDP). Conclusions: 3Ao/cDDP, induced by cisplatin and established by imitating the characteristics of clinical chemotherapy for epithelial ovarian cancer, was an ideal model for investigation of cisplatin resistance in vitro. Cisplatin resistance in 3Ao/cDDP could be accounted for by higher LRP, GSTp and lower TopoII expression and was not associated with MRP or P-gp. Ligustrazine had no significant reversal effect on cisplatin resistance, but cyclosporin A could reverse the resistance effectively.

  5. An integrated mechanical-enzymatic reverse osmosis treatment of dairy industry wastewater and milk protein recovery as a fat replacer: a closed loop approach

    Directory of Open Access Journals (Sweden)

    F. Sarghini

    2013-09-01

    Full Text Available The dairy industry can be classified among the most polluting of the food industries in volume in regard to its large water consumption, generating from 0.2 to 10 L of effluent per liter of processed milk. Dairy industry effluents usually include highly dissolved organic matter with varying characteristics, and a correct waste management project is required to handle. In a framework of natural water resource availability and cost increase, wastewater treatment for water reuse can lower the overall water consumption and the global effluent volume of industrial plants. Moreover, correct dismissal of dairy industry wastewater is sometimes neglected by the operators , increasing the environmental impact due to the chemical and biological characteristics of such effluents. On the other hand, in the case of whey effluents, several by-products are still present inside, such as lactose and milk proteins. Membrane technology has some advantages including a high degree of reliability in removing dissolved, colloidal and particulate matter, like the selectivity in size of pollutants to be removed and the possibility of very compact treatment plants. For example, Reverse Osmosis (RO technology has been successfully applied for the treatment of dairy wastes (1, and as a technology for concentration and fractionation of whey. In this work a membrane treatment approach using reverse osmosis technology is investigated and implemented: the permeate obtained can be reused as clean warm water for cleaning and sanitation of production plants, while concentrated milk proteins are modified by using transglutaminase enzyme obtaining a high temperature resistant fat replacer to be used in different low-fat products like for example mozzarella cheese.

  6. Mechanism of equivalent electric dipole oscillation for high-order harmonic generation from grating-structured solid-surface by femtosecond laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yang; Song, Hai-Ying; Liu, H.Y.; Liu, Shi-Bing, E-mail: sbliu@bjut.edu.cn

    2017-07-12

    Highlights: • Proposed a valid mechanism of high harmonic generation by laser grating target interaction: oscillation of equivalent electric dipole (OEED). • Found that there also exist harmonic emission at large emission angle but not just near-surface direction as the former researches had pointed out. • Show the process of the formation and motion of electron bunches at the grating-target surface irradiating with femtosecond laser pulse. - Abstract: We theoretically study high-order harmonic generation (HHG) from relativistically driven overdense plasma targets with rectangularly grating-structured surfaces by femtosecond laser pulses. Our particle-in-cell (PIC) simulations show that, under the conditions of low laser intensity and plasma density, the harmonics emit principally along small angles deviating from the target surface. Further investigation of the surface electron dynamics reveals that the electron bunches are formed by the interaction between the laser field and the target surface, giving rise to the oscillation of equivalent electric-dipole (OEED), which enhances specific harmonic orders. Our work helps understand the mechanism of harmonic emissions from grating targets and the distinction from the planar harmonic scheme.

  7. Predominance of the second-order, two-step mechanism in the electron impact double ionization of helium at intermediate impact energy

    Energy Technology Data Exchange (ETDEWEB)

    Lahmam-Bennani, A; Casagrande, E M Staicu; Naja, A [Institut des Sciences Moleculaires d' Orsay (ISMO), Universite Paris-Sud 11, Bat. 351, 91405 Orsay Cedex (France); Dal Cappello, C [Laboratoire de Physique Moleculaire et des Collisions, ICPMB (FR 2843), Institut de Physique, Universite Paul Verlaine-Metz, 1 rue Arago, 57078 Metz Cedex 3 (France); Bolognesi, P, E-mail: azzedine.bennani@u-psud.f [CNR-IMIP, Area della Ricerca di Roma 1, CP 10, 00016 Monterotondo Scalo (Italy)

    2010-05-28

    The (e,3-1e) four-fold differential cross sections (4DCS) are measured for the double ionization of helium in coplanar asymmetric geometry for a wide range of ejected electron energies and at an incident energy of about 600 eV. The experimental angular distributions of the 4DCS are characterized by large angular shifts of the forward and backward lobes with respect to the momentum transfer direction or its opposite, respectively. This validates our previously published results (Lahmam-Bennani et al 2002 J. Phys. B: At. Mol. Opt. Phys. 35 L59) which were questioned by Goetz et al (2003 J. Phys. B: At. Mol. Opt. Phys. 36 L77). A qualitative, kinematical analysis is given which allows relating these shifts and the observed structures in the intensity distributions to the second-order, 'two-step 2' double ionization mechanism, which is shown to predominate over the first-order 'shake-off' and 'two-step 1' mechanisms under the present kinematics.

  8. Flap endonucleases pass 5'-flaps through a flexible arch using a disorder-thread-order mechanism to confer specificity for free 5'-ends.

    Science.gov (United States)

    Patel, Nikesh; Atack, John M; Finger, L David; Exell, Jack C; Thompson, Peter; Tsutakawa, Susan; Tainer, John A; Williams, David M; Grasby, Jane A

    2012-05-01

    Flap endonucleases (FENs), essential for DNA replication and repair, recognize and remove RNA or DNA 5'-flaps. Related to FEN specificity for substrates with free 5'-ends, but controversial, is the role of the helical arch observed in varying conformations in substrate-free FEN structures. Conflicting models suggest either 5'-flaps thread through the arch, which when structured can only accommodate single-stranded (ss) DNA, or the arch acts as a clamp. Here we show that free 5'-termini are selected using a disorder-thread-order mechanism. Adding short duplexes to 5'-flaps or 3'-streptavidin does not markedly impair the FEN reaction. In contrast, reactions of 5'-streptavidin substrates are drastically slowed. However, when added to premixed FEN and 5'-biotinylated substrate, streptavidin is not inhibitory and complexes persist after challenge with unlabelled competitor substrate, regardless of flap length or the presence of a short duplex. Cross-linked flap duplexes that cannot thread through the structured arch react at modestly reduced rate, ruling out mechanisms involving resolution of secondary structure. Combined results explain how FEN avoids cutting template DNA between Okazaki fragments and link local FEN folding to catalysis and specificity: the arch is disordered when flaps are threaded to confer specificity for free 5'-ends, with subsequent ordering of the arch to catalyze hydrolysis.

  9. 埋栅型电力静电感应晶闸管的Ⅰ-Ⅴ特性反向转折机理%Mechanism of Reverse Snapback on Ⅰ-Ⅴ Characteristics of Power SITHs with Buried Gate Structure

    Institute of Scientific and Technical Information of China (English)

    王永顺; 李海蓉; 吴蓉; 李思渊

    2008-01-01

    The reverse snapback phenomena (RSP) on Ⅰ-Ⅴ characteristics of static induction thyristors (SITH) are physi- cally researched. The Ⅰ-Ⅴ curves of the power SITH exhibit reverse snapback phenomena, and even turn to the conducting-state,when the anode voltage in the forward blocking-state is increased to a critical value. The RSP Ⅰ-Ⅴ characteristics of the power SITH are analyzed in terms of operating mechanism, double carrier injection effect, space charge effect, elec-tron-hole plasma in the channel, and the variation in carrier lifetime. The reverse snapback mechanism is theoretically pro-posed and the mathematical expressions to calculate the voltage and current values at the snapback point are presented.The computing results are compared with the experiment values.%研究了静电感应晶闸管的反向转折特性.当工作在正向阻断态的阳极电压增大到某一临界值时,静电感应晶闸管的Ⅰ-Ⅴ曲线呈现出反向转折特性,甚至转向导通态.在综合考虑了工作机理、双注入效应、空间电荷效应、沟道中的电子-空穴等离子体和载流子寿命变化的基础上分析了静电感应晶闸管的反向转折特性.首次给出了反向转折机理的理论解释,并给出了估算转折电压和电流的数学表达式,在常用工艺参数范围内,计算结果和实验测量值基本一致.

  10. Managing Reverse Logistics or Reversing Logistics Management?

    OpenAIRE

    Brito, Marisa

    2004-01-01

    textabstractIn the past, supply chains were busy fine-tuning the logistics from raw material to the end customer. Today an increasing flow of products is going back in the chain. Thus, companies have to manage reverse logistics as well.This thesis contributes to a better understanding of reverse logistics. The thesis brings insights on reverse logistics decision-making and it lays down theoretical principles for reverse logistics as a research field.In particular it puts together a framework ...

  11. Ordered self-assembly mechanism of a spherical oncoprotein oligomer triggered by zinc removal and stabilized by an intrinsically disordered domain.

    Directory of Open Access Journals (Sweden)

    Clara Smal

    Full Text Available BACKGROUND: Self-assembly is a common theme in proteins of unrelated sequences or functions. The human papillomavirus E7 oncoprotein is an extended dimer with an intrinsically disordered domain, that can form large spherical oligomers. These are the major species in the cytosol of HPV transformed and cancerous cells. E7 binds to a large number of targets, some of which lead to cell transformation. Thus, the assembly process not only is of biological relevance, but represents a model system to investigate a widely distributed mechanism. METHODOLOGY/PRINCIPAL FINDINGS: Using various techniques, we monitored changes in secondary, tertiary and quaternary structure in a time course manner. By applying a robust kinetic model developed by Zlotnik, we determined the slow formation of a monomeric "Z-nucleus" after zinc removal, followed by an elongation phase consisting of sequential second-order events whereby one monomer is added at a time. This elongation process takes place at a strikingly slow overall average rate of one monomer added every 28 seconds at 20 µM protein concentration, strongly suggesting either a rearrangement of the growing complex after binding of each monomer or the existence of a "conformation editing" mechanism through which the monomer binds and releases until the appropriate conformation is adopted. The oligomerization determinant lies within its small 5 kDa C-terminal globular domain and, remarkably, the E7 N-terminal intrinsically disordered domain stabilizes the oligomer, preventing an insoluble amyloid route. CONCLUSION: We described a controlled ordered mechanism with features in common with soluble amyloid precursors, chaperones, and other spherical oligomers, thus sharing determining factors for symmetry, size and shape. In addition, such a controlled and discrete polymerization reaction provides a valuable tool for nanotechnological applications. Finally, its increased immunogenicity related to its supramolecular

  12. Effects of alloying and local order in AuNi contacts for Ohmic radio frequency micro electro mechanical systems switches via multi-scale simulation

    Science.gov (United States)

    Gaddy, Benjamin E.; Kingon, Angus I.; Irving, Douglas L.

    2013-05-01

    Ohmic RF-MEMS switches hold much promise for low power wireless communication, but long-term degradation currently plagues their reliable use. Failure in these devices occurs at the contact and is complicated by the fact that the same asperities that bear the mechanical load are also important to the flow of electrical current needed for signal processing. Materials selection holds the key to overcoming the barriers that prevent widespread use. Current efforts in materials selection have been based on the material's (or alloy's) ability to resist oxidation as well as its room-temperature properties, such as hardness and electrical conductivity. No ideal solution has yet been found via this route. This may be due, in part, to the fact that the in-use changes to the local environment of the asperity are not included in the selection criteria. For example, Joule heating would be expected to raise the local temperature of the asperity and impose a non-equilibrium thermal gradient in the same region expected to respond to mechanical actuation. We propose that these conditions should be considered in the selection process, as they would be expected to alter mechanical, electrical, and chemical mechanisms in the vicinity of the surface. To this end, we simulate the actuation of an Ohmic radio frequency micro electro mechanical systems switch by using a multi-scale method to model a current-carrying asperity in contact with a polycrystalline substrate. Our method couples continuum solutions of electrical and thermal transport equations to an underlying molecular dynamics simulation. We present simulations of gold-nickel asperities and substrates in order to evaluate the influence of alloying and local order on the early stages of contact actuation. The room temperature response of these materials is compared to the response of the material when a voltage is applied. Au-Ni interactions are accounted for through modification of the existing Zhou embedded atom method

  13. Multi-round reverse combinatorial auction mechanism allowing incomplete auction%允许不完全拍卖的多轮逆向组合拍卖机制

    Institute of Scientific and Technical Information of China (English)

    祁宁; 汪定伟

    2013-01-01

    物品之间的互补性和替代性使得逆向组合拍卖成为较为有效的采购方式.设计了一种允许不完全拍卖的多轮逆向组合拍卖机制,并设计了基于预处理规则的改进最大-最小蚁群算法(MMAS) ——PRIM(preprocessing rules-based improved MMAS),求解每轮的胜标确定问题.结果表明,允许不完全拍卖的多轮拍卖机制能够显著地降低采购成本.%In procurement, if there are complementarities or substitutabilities between the goods, a combinatorial reverse auction can be beneficial. In this paper, we present a multi-round bidding mechanism, in which incomplete bidding is allowed, and show that much more procurement cost can be saved evidently by using this mechanism. A common model is formulated and a PRIM ( preprocessing rules-based improved MMAS) algorithm is adopted in solving the winner determination problem of reverse combinatorial auction in every round.

  14. Collagen insulated from tensile damage by domains that unfold reversibly: in situ X-ray investigation of mechanical yield and damage repair in the mussel byssus.

    Science.gov (United States)

    Harrington, Matthew J; Gupta, Himadri S; Fratzl, Peter; Waite, J Herbert

    2009-07-01

    The byssal threads of the California mussel, Mytilus californianus, are highly hysteretic, elastomeric fibers that collectively perform a holdfast function in wave-swept rocky seashore habitats. Following cyclic loading past the mechanical yield point, threads exhibit a damage-dependent reduction in mechanical performance. However, the distal portion of the byssal thread is capable of recovering initial material properties through a time-dependent healing process in the absence of active cellular metabolism. Byssal threads are composed almost exclusively of multi-domain hybrid collagens known as preCols, which largely determine the mechanical properties of the thread. Here, the structure-property relationships that govern thread mechanical performance are further probed. The molecular rearrangements that occur during yield and damage repair were investigated using time-resolved in situ wide-angle X-ray diffraction (WAXD) coupled with cyclic tensile loading of threads and through thermally enhanced damage-repair studies. Results indicate that the collagen domains in byssal preCols are mechanically protected by the unfolding of sacrificial non-collagenous domains that refold on a slower time-scale. Time-dependent healing is primarily attributed to stochastic recoupling of broken histidine-metal coordination complexes.

  15. Mechanisms involved in the inhibition of glycolysis by cyanide and antimycin A in Candida albicans and its reversal by hydrogen peroxide. A common feature in Candida species.

    Science.gov (United States)

    Peña, Antonio; Sánchez, Norma Silvia; González-López, Omar; Calahorra, Martha

    2015-12-01

    In Candida albicans, cyanide and antimycin A inhibited K(+) transport, not only with ethanol-O2 as the substrate, but also with glucose. The reason for this was that they inhibited not only respiration, but also fermentation, decreasing ATP production. Measurements of oxygen levels in cell suspensions allowed identification of the electron pathways involved. NADH fluorescence levels increased in the presence of the inhibitors, indirectly indicating lower levels of NAD(+) and so pointing to glyceraldehyde-3-phosphate dehydrogenase as the limiting step responsible for the inhibition of glycolysis, which was confirmed by the levels of glycolytic intermediaries. The cyanide effect could be reversed by hydrogen peroxide, mainly due to an activity by which H2O2 can be reduced by electrons flowing from NADH through a pathway that can be inhibited by antimycin A, and appears to be a cytochrome c peroxidase. Therefore, the inhibition of glycolysis by the respiratory inhibitors seems to be due to the decreased availability of NAD(+), resulting in a decreased activity of glyceraldehyde-3-phosphate dehydrogenase. Compartmentalization of pyridine nucleotides in favor of the mitochondria can contribute to explaining the low fermentation capacity of C. albicans. Similar results were obtained with three C. albicans strains, Candida dubliniensis and, to a lower degree, Candida parapsilosis.

  16. Managing Reverse Logistics or Reversing Logistics Management?

    NARCIS (Netherlands)

    M.P. de Brito (Marisa)

    2004-01-01

    textabstractIn the past, supply chains were busy fine-tuning the logistics from raw material to the end customer. Today an increasing flow of products is going back in the chain. Thus, companies have to manage reverse logistics as well.This thesis contributes to a better understanding of reverse

  17. Managing Reverse Logistics or Reversing Logistics Management?

    NARCIS (Netherlands)

    M.P. de Brito (Marisa)

    2004-01-01

    textabstractIn the past, supply chains were busy fine-tuning the logistics from raw material to the end customer. Today an increasing flow of products is going back in the chain. Thus, companies have to manage reverse logistics as well.This thesis contributes to a better understanding of reverse log

  18. Compositional dependence of magnetization reversal mechanism, magnetic interaction and Curie temperature of Co{sub 1−x}Sr{sub x}Fe{sub 2}O{sub 4} spinel thin film

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemi, Ali, E-mail: ali13912001@yahoo.com

    2015-10-05

    Highlights: • Nanoparticles and thin films of Co{sub 1−x}Sr{sub x}Fe{sub 2}O{sub 4} were successfully synthesized by a sol–gel process. • The value of strength of interaction was enhanced from −0.23 for x = 0 to −0.75 for x = 0.5. • The magnetization reversal process for x = 0, 0.1 was almost controlled by Kondorsky models. • The reversal mechanism for x = 0.2–0.5 obey the Stoner–Wohlfarth rule. - Abstract: Co{sub 1−x}Sr{sub x}Fe{sub 2}O{sub 4}, (x varies from 0 to 0.5 in a step of 0.1) nanoparticles were formed by means of sol–gel processing method. The morphological and structural features of nanoparticles were evaluated by Fourier transform infrared spectroscopy, field emission scanning electron microscopy (FE-SEM) equipped by EDS analysis, Mössbauer spectroscopy and vibrating sample magnetometer. It was found that almost narrow size distribution of nanoparticles with cation distribution occupancy preference in octahedral site was synthesized. The nanoparticles were used for addition in subsequent solution for fabricating ferrite thin films with similar mentioned chemical composition. Several techniques including FE-SEM, atomic force microscopy and vibrating sample magnetometer were employed to find the role of strontium cation distribution on the structural and magnetic properties of films. The Curie temperature, coercivity and magnetic interaction which was evaluated by Henkel plot were reduced by an increase in substitution contents. Coercivity of thin films reduced from 0.65 MA/m to 0.39 MA/m and Curie temperature declined from 690 to 455 °C. The value of strength of interaction was enhanced from −0.23 for x = 0 to −0.75 for x = 0.5. Angular dependence of coercivity proved that the magnetization reversal process was accompanied by the combination of domain wall motion and Stoner–Wohlfarth rotation, however for thin film with x = 0.2–0.5, the reversal mechanism obey the Stoner–Wohlfarth rule.

  19. K70Q adds high-level tenofovir resistance to "Q151M complex" HIV reverse transcriptase through the enhanced discrimination mechanism.

    Directory of Open Access Journals (Sweden)

    Atsuko Hachiya

    Full Text Available HIV-1 carrying the "Q151M complex" reverse transcriptase (RT mutations (A62V/V75I/F77L/F116Y/Q151M, or Q151Mc is resistant to many FDA-approved nucleoside RT inhibitors (NRTIs, but has been considered susceptible to tenofovir disoproxil fumarate (TFV-DF or TDF. We have isolated from a TFV-DF-treated HIV patient a Q151Mc-containing clinical isolate with high phenotypic resistance to TFV-DF. Analysis of the genotypic and phenotypic testing over the course of this patient's therapy lead us to hypothesize that TFV-DF resistance emerged upon appearance of the previously unreported K70Q mutation in the Q151Mc background. Virological analysis showed that HIV with only K70Q was not significantly resistant to TFV-DF. However, addition of K70Q to the Q151Mc background significantly enhanced resistance to several approved NRTIs, and also resulted in high-level (10-fold resistance to TFV-DF. Biochemical experiments established that the increased resistance to tenofovir is not the result of enhanced excision, as K70Q/Q151Mc RT exhibited diminished, rather than enhanced ATP-based primer unblocking activity. Pre-steady state kinetic analysis of the recombinant enzymes demonstrated that addition of the K70Q mutation selectively decreases the binding of tenofovir-diphosphate (TFV-DP, resulting in reduced incorporation of TFV into the nascent DNA chain. Molecular dynamics simulations suggest that changes in the hydrogen bonding pattern in the polymerase active site of K70Q/Q151Mc RT may contribute to the observed changes in binding and incorporation of TFV-DP. The novel pattern of TFV-resistance may help adjust therapeutic strategies for NRTI-experienced patients with multi-drug resistant (MDR mutations.

  20. Identification of the Mechanisms Causing Reversion to Virulence in an Attenuated SARS-CoV for the Design of a Genetically Stable Vaccine.

    Science.gov (United States)

    Jimenez-Guardeño, Jose M; Regla-Nava, Jose A; Nieto-Torres, Jose L; DeDiego, Marta L; Castaño-Rodriguez, Carlos; Fernandez-Delgado, Raul; Perlman, Stanley; Enjuanes, Luis

    2015-10-01

    A SARS-CoV lacking the full-length E gene (SARS-CoV-∆E) was attenuated and an effective vaccine. Here, we show that this mutant virus regained fitness after serial passages in cell culture or in vivo, resulting in the partial duplication of the membrane gene or in the insertion of a new sequence in gene 8a, respectively. The chimeric proteins generated in cell culture increased virus fitness in vitro but remained attenuated in mice. In contrast, during SARS-CoV-∆E passage in mice, the virus incorporated a mutated variant of 8a protein, resulting in reversion to a virulent phenotype. When the full-length E protein was deleted or its PDZ-binding motif (PBM) was mutated, the revertant viruses either incorporated a novel chimeric protein with a PBM or restored the sequence of the PBM on the E protein, respectively. Similarly, after passage in mice, SARS-CoV-∆E protein 8a mutated, to now encode a PBM, and also regained virulence. These data indicated that the virus requires a PBM on a transmembrane protein to compensate for removal of this motif from the E protein. To increase the genetic stability of the vaccine candidate, we introduced small attenuating deletions in E gene that did not affect the endogenous PBM, preventing the incorporation of novel chimeric proteins in the virus genome. In addition, to increase vaccine biosafety, we introduced additional attenuating mutations into the nsp1 protein. Deletions in the carboxy-terminal region of nsp1 protein led to higher host interferon responses and virus attenuation. Recombinant viruses including attenuating mutations in E and nsp1 genes maintained their attenuation after passage in vitro and in vivo. Further, these viruses fully protected mice against challenge with the lethal parental virus, and are therefore safe and stable vaccine candidates for protection against SARS-CoV.

  1. Reversible Thermoset Adhesives

    Science.gov (United States)

    Mac Murray, Benjamin C. (Inventor); Tong, Tat H. (Inventor); Hreha, Richard D. (Inventor)

    2016-01-01

    Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry.

  2. Growth, optical, thermal, mechanical and dielectric studies of sodium succinate hexahydrate (β phase) single crystal: A promising third order NLO material

    Science.gov (United States)

    Mageshwari, P. S. Latha; Priya, R.; Krishnan, S.; Joseph, V.; Das, S. Jerome

    2016-11-01

    A third order nonlinear optical (NLO)single crystals of sodium succinate hexahydrate (SSH) (β phase) has been grown by a slow evaporation growth technique using aqueous solution at ambient temperature. The lattice parameters and morphology of SSH were determined by single crystal X-ray diffraction analysis. SSH crystallizes in centrosymmetric monoclinic system with space group P 21 / c and the crystalline purity was analyzed by powder X-ray diffraction analysis. The UV-vis-NIR spectrum reveals that the crystal is transparent in the entire visible region. The recorded FT-IR spectrum verified the presence of various functional groups in the material. NMR analysis of the grown crystal confirms the structural elucidation and detects the major and minor functional groups present in the title compound. ICP-OES analysis proved the presence of sodium in SSH. TG-DTA/DSCanalysis was used to investigate the thermal stability of the material. The dielectric permittivity and dielectric loss of SSH were carried out as a function of frequency for different temperatures and the results were discussed. The mechanical stability was evaluated from Vicker's microhardness test. The third order nonlinear optical properties of SSH has been investigated employing Z-scan technique with He-Ne laser operating at 632.8 nm wavelength.

  3. Investigation of fluctuations of the oxygen order in YBa sub 2 Cu sub 3 O sub x near the orthorhombic-to-tetragonal phase transition using mechanical spectroscopy

    CERN Document Server

    Foos, K

    2000-01-01

    given above. YBa-2Cu-3O-x (concentrations x between 6 and 7) has a tetragonal and a number of orthorhombic structures that correspond to different oxygen configurations in the Cu(1) planes. The oxygen atoms in these planes occupy two types of interstitial sites. In the tetragonal phase, both types of sites are occupied with same probability, whereas the occupation probabilities differ in the orthorhombic phases. Thus the tetragonal-to-orthorhombic phase transition is combined with an disorder-to-order transition. It is, at least above 600 K, of second order. At the transition the amplitude and the correlation time of the fluctuations of the oxygen configuration should diverge. This macroscopic yields ferroelastic behavior and critical slowing-down of the inelastic relaxation rate, respectively. This work gives evidences for this behavior. We studied energy dissipation and elastic modulus behavior of YBa-2Cu-3O-x samples by mechanical spectroscopy (temperatures from 400 to 1000 K, vibrating reed technique, fre...

  4. Modulation of glutamatergic transmission by presynaptic N-methyl-D-aspartate mechanisms in second-order neurons of the rat nucleus tractus solitarius.

    Science.gov (United States)

    Ohi, Yoshiaki; Kimura, Satoko; Haji, Akira

    2015-02-05

    The present study investigated the physiological function of presynaptic N-methyl-d aspartate (NMDA) mechanisms in glutamatergic transmission in the rat nucleus tractus solitarius (NTS). Membrane currents were recorded from the NTS second-order neurons by using whole-cell patch pipettes including MK-801 to block postsynaptic NMDA receptors. All experiments were performed under blockade of inhibitory synaptic transmission. Co-application of NMDA and d-serine decreased the tractus solitarius (TS)-evoked excitatory postsynaptic currents (eEPSCs) in 7/12 (58%) of neurons, and increased the paired pulse ratio. The remaining neurons were insensitive to NMDA and d-serine. Application of an NMDA antagonist D-AP5 had no effect on eEPSCs in all 8 neurons tested. Action potential-independent EPSCs (miniature EPSCs; mEPSCs) were recorded in the presence of tetrodotoxin. Co-application of NMDA and d-serine increased the mEPSC frequency but had no significant effect on the amplitude in 5/28 (18%) of neurons. D-AP5 decreased the mEPSC frequency without effect on the amplitude in 6/18 (33%) of neurons. This study demonstrated that (1) NMDA receptors were presynaptically distributed in a subset of NTS second-order neurons and that (2) the presynaptic NMDA receptors played an inhibitory role in TS-mediated release of glutamate and a facilitatory role in spontaneous release of glutamate. The present results suggest that the activation of presynaptic NMDA receptors modulates glutamatergic transmissions in the rat NTS second-order neurons.

  5. Microstructure and mechanical properties of a compound reinforced Mg95Y2.5Zn2.5 alloy with long period stacking ordered phase and W phase

    Directory of Open Access Journals (Sweden)

    Shou-zhong Wu

    2017-01-01

    Full Text Available The microstructure evolution of Mg100-2xYxZnx (x=2, 2.5, 3, 3.5 alloys was investigated. Results show that the Mg100-2xYxZnx alloys are composed of α-Mg, long period stacking ordered (LPSO phase and eutectic structure phase (W phase, and the Mg95Y2.5Zn2.5 alloy has the best comprehensive mechanical properties. Subsequently, the microstructure evolution of the optimized alloy Mg95Y2.5Zn2.5 during solidification and heat treatment processes was analyzed and discussed by means of OM, SEM, TEM, XRD and DTA. After heat treatment, the lamellar phase 14H-LPSO precipitated in α-Mg and W phase transforms into particle phase (MgYZn2. Due to the compound reinforcement effect of the particle phase and LPSO phase (18R+14H, the mechanical properties of the alloy are enhanced. The tensile strength and elongation of the Mg95Y2.5Zn2.5 alloy is improved by 9.1% and 31.3% to 215 MPa and 10.5%, respectively, after solid-solution treatment.

  6. Reduct and Attribute Order

    Institute of Scientific and Technical Information of China (English)

    Su-Qing Han; Jue Wang

    2004-01-01

    Based on the principle of discernibility matrix,a kind of reduction algorithm with attribute order has been developed and its solution has been proved to be complete for reduct and unique for a given attribute order.Being called the reduct problem,this algorithm can be regarded as a mapping R = Reduct(S)from the attribute order space θ to the reduct space R for an information system ,where U is the universe and C and D are two sets of condition and decision attributes respectively.This paper focuses on the reverse problem of reduct problem S = Order(R),i.e.,for a given reduct R of an information system,we determine the solution of S = Order(R)in the space θ.First,we need to prove that there is at least one attribute order S such that S = Order(R).Then,some decision rules are proposed,which can be used directly to decide whether the pair of attribute orders has the same reduct.The main method is based on the fact that an attribute order can be transformed into another one by moving the attribute for limited times.Thus,the decision of the pair of attribute orders can be altered to the decision of the sequence of neighboring pairs of attribute orders.Therefore,the basic theorem of neighboring pair of attribute orders is first proved,then,the decision theorem of attribute order is proved accordingly by the second attribute.

  7. Successful reversal of propionic acidaemia associated cardiomyopathy: evidence for low myocardial coenzyme Q10 status and secondary mitochondrial dysfunction as an underlying pathophysiological mechanism.

    Science.gov (United States)

    Baruteau, J; Hargreaves, I; Krywawych, S; Chalasani, A; Land, J M; Davison, J E; Kwok, M K; Christov, G; Karimova, A; Ashworth, M; Anderson, G; Prunty, H; Rahman, S; Grünewald, S

    2014-07-01

    Dilated cardiomyopathy is a rare complication in propionic acidaemia (PA). Underlying pathophysiological mechanisms are poorly understood. We present a child of Pakistani consanguineous parents, diagnosed with late-onset PA at 18months of age. He presented a mild phenotype, showed no severe further decompensations, normal growth and psychomotor development on a low protein diet and carnitine supplementation. At 15years, a mildly dilated left ventricle was noticed. At 17years he presented after a 2-3month history of lethargy and weight loss with severe decompensated dilated cardiomyopathy. He was stabilised on inotropic support and continuous haemofiltration; a Berlin Heart biventricular assist device was implanted. He received d,l-hydroxybutyrate 200mg/kg/day, riboflavin and thiamine 200mg/day each and coenzyme Q10 (CoQ10). Myocardial biopsy showed endocardial fibrosis, enlarged mitochondria, with atypical cristae and slightly low respiratory chain (RC) complex IV activity relative to citrate synthase (0.012, reference range 0.014-0.034). Myocardial CoQ10 was markedly decreased (224pmol/mg, reference range 942-2738), with a marginally decreased white blood cell level (34pmol/mg reference range 37-133). The dose of CoQ10 was increased from 1.5 to 25mg/kg/day. Cardiomyopathy slowly improved allowing removal of the external mechanical cardiac support after 67days. We demonstrate for the first time low myocardial CoQ10 in cardiomyopathy in PA, highlighting secondary mitochondrial impairment as a relevant causative mechanism. According to these findings, a high-dose CoQ10 supplementation could be a potential adjuvant therapeutic to be considered in PA-related cardiomyopathy.

  8. Reverse logistics - a framework

    OpenAIRE

    Brito, Marisa; Dekker, Rommert

    2002-01-01

    textabstractIn this paper we define and compare Reverse Logistics definitions. We start by giving an understanding framework of Reverse Logistics: the why-what-how. By this means, we put in context the driving forces for Reverse Logistics, a typology of return reasons, a classification of products, processes and actors. In addition we provide a decision framework for Reverse Logistics and we present it according to long, medium and short term decisions, i.e. strategic-tactic-operational decis...

  9. Reverse cholesterol transport revisited

    Institute of Scientific and Technical Information of China (English)

    Astrid; E; van; der; Velde

    2010-01-01

    Reverse cholesterol transport was originally described as the high-density lipoprotein-mediated cholesterol flux from the periphery via the hepatobiliary tract to the intestinal lumen, leading to fecal excretion. Since the introduction of reverse cholesterol transport in the 1970s, this pathway has been intensively investigated. In this topic highlight, the classical reverse cholesterol transport concepts are discussed and the subject reverse cholesterol transport is revisited.

  10. Securing Biometric Images using Reversible Watermarking

    CERN Document Server

    Thampi, Sabu M

    2011-01-01

    Biometric security is a fast growing area. Protecting biometric data is very important since it can be misused by attackers. In order to increase security of biometric data there are different methods in which watermarking is widely accepted. A more acceptable, new important development in this area is reversible watermarking in which the original image can be completely restored and the watermark can be retrieved. But reversible watermarking in biometrics is an understudied area. Reversible watermarking maintains high quality of biometric data. This paper proposes Rotational Replacement of LSB as a reversible watermarking scheme for biometric images. PSNR is the regular method used for quality measurement of biometric data. In this paper we also show that SSIM Index is a better alternate for effective quality assessment for reversible watermarked biometric data by comparing with the well known reversible watermarking scheme using Difference Expansion.

  11. Conjugation-Driven "Reverse Mars-van Krevelen"-Type Radical Mechanism for Low-Temperature C-O Bond Activation.

    Science.gov (United States)

    Mironenko, Alexander V; Vlachos, Dionisios G

    2016-07-01

    C-O bond activation on monofunctional catalysts (metals, carbides, and oxides) is challenging due to activity constraints imposed by energy scaling relationships. Yet, contrary to predictions, recently discovered multifunctional metal/metal oxide catalysts (e.g., Rh/ReOx, Rh/MoOx, Ir/VOx) demonstrate unusually high C-O scission activity at moderate temperatures. Herein, we use extensive density functional theory calculations, first-principles microkinetic modeling, and electronic structure analysis to elucidate the metal/metal oxide synergy in the Ru/RuO2 catalyst, which enables up to 76% yield of the C-O scission product (2-methyl furan) in catalytic transfer hydrogenolysis of furfural at low temperatures. Our key mechanistic finding is a facile radical-mediated C-O bond activation on RuO2 oxygen vacancies, which directly leads to a weakly bound final product. This is the first time the radical reduction mechanism is reported in heterogeneous catalysis at temperatures Mo2C. Furthermore, we reveal the cooperativity of active sites in multifunctional catalysts. The mechanism is fully consistent with kinetic studies and isotopic labeling experiments, and the insights gained might prove useful more broadly in overcoming activity constraints induced by energy scaling relationships.

  12. Cylindrical air flow reversal barrier

    Energy Technology Data Exchange (ETDEWEB)

    Woznica, C.; Rodziewicz, M.

    1988-06-01

    Describes an innovative design introduced in the ZMP mine in Zory for quick reversal of ventilation air flow. Geologic mining conditions at the 705 m deep horizon, where the barrier was built, are described. According to the design used until now, a reversal system consisted of safety barriers, ventilation air locks, a ventilation bridge and stopping needed in case of a fire when air flow direction must be reversed. Nine air locks and an expensive concrete ventilation bridge were needed and the air locks had to be operated at 8 points of the region to effect reversal. The new design consists of a 2-storey cylindrical barrier which also fulfills the function of a ventilation bridge. It can be manually or remotely operated by a mechanical or pneumatic system. Tests showed that the new barrier permits immediate air flow reversal while retaining 60% of the original air, which is important in the case of fire and methane hazards. It permits improved seam panelling and splitting of pillars and brings an economy of about 40 million zlotys in construction cost. Design and operation of the barrier is illustrated and ventilation air circulation is explained. 7 figs.

  13. Reverse logistics - a framework

    NARCIS (Netherlands)

    M.P. de Brito (Marisa); R. Dekker (Rommert)

    2002-01-01

    textabstractIn this paper we define and compare Reverse Logistics definitions. We start by giving an understanding framework of Reverse Logistics: the why-what-how. By this means, we put in context the driving forces for Reverse Logistics, a typology of return reasons, a classification of product

  14. Reverse Engineering Adverse Outcome Pathways in Ecotoxicology

    Science.gov (United States)

    The toxicological effects of many stressors are mediated through unknown, or incompletely characterized, mechanisms of action. We describe the application of reverse engineering complex interaction networks from high dimensional omics data (gene, protein, meabolic, signaling) t...

  15. Reversed straining in axisymmetric compression test

    DEFF Research Database (Denmark)

    Arentoft, Mogens; Wanheim, Tarras; Lindegren, Maria

    2005-01-01

    A large group of the cold forging processes is carried out in a thick – walled container with the deformation force transmitted through a punch moving axially in the container. The work piece, being entrapped between punch and container will expand and exert a radial pressure resulting in an expa......A large group of the cold forging processes is carried out in a thick – walled container with the deformation force transmitted through a punch moving axially in the container. The work piece, being entrapped between punch and container will expand and exert a radial pressure resulting...... in an expansion of the bore. After unloading, the container will try to reduce this expansion and thus in many cases cause a reversed plastic deformation of the work-piece. This will have an effect on the resulting diameter of the work-piece and – above all – on the resulting mechanical properties. In order...

  16. Magnetic reversals from planetary dynamo waves.

    Science.gov (United States)

    Sheyko, Andrey; Finlay, Christopher C; Jackson, Andrew

    2016-11-24

    A striking feature of many natural dynamos is their ability to undergo polarity reversals. The best documented example is Earth's magnetic field, which has reversed hundreds of times during its history. The origin of geomagnetic polarity reversals lies in a magnetohydrodynamic process that takes place in Earth's core, but the precise mechanism is debated. The majority of numerical geodynamo simulations that exhibit reversals operate in a regime in which the viscosity of the fluid remains important, and in which the dynamo mechanism primarily involves stretching and twisting of field lines by columnar convection. Here we present an example of another class of reversing-geodynamo model, which operates in a regime of comparatively low viscosity and high magnetic diffusivity. This class does not fit into the paradigm of reversal regimes that are dictated by the value of the local Rossby number (the ratio of advection to Coriolis force). Instead, stretching of the magnetic field by a strong shear in the east-west flow near the imaginary cylinder just touching the inner core and parallel to the axis of rotation is crucial to the reversal mechanism in our models, which involves a process akin to kinematic dynamo waves. Because our results are relevant in a regime of low viscosity and high magnetic diffusivity, and with geophysically appropriate boundary conditions, this form of dynamo wave may also be involved in geomagnetic reversals.

  17. Comparison between Prothrombin Complex Concentrate (PCC) and Fresh Frozen Plasma (FFP) for the Urgent Reversal of Warfarin in Patients with Mechanical Heart Valves in a Tertiary Care Cardiac Center.

    Science.gov (United States)

    Fariborz Farsad, Bahram; Golpira, Reza; Najafi, Hamideh; Totonchi, Ziae; Salajegheh, Shirin; Bakhshandeh, Hooman; Hashemian, Farshad

    2015-01-01

    Fresh frozen plasma (FFP) and prothrombin complex concentrate (PCC) reverse oral anticoagulants such as Warfarin. We compared the standard dosage of FFP and PCC in terms of efficacy and safety for patients with mechanical heart valves undergoing interventional procedures while receiving Warfarin. Fifty patients were randomized (25 for each group) with mechanical heart valves [international normalized ratio (INR) >2.5]. FFP dosage was administered based on body weight (10-15 mL/Kg), while PCC dosage was administered based on both body weight and target INR. INR measurements were obtained at different time after PCC and FFP infusion. The mean ± SD of INR pre treatment was not significantly different between the PCC and FFP groups. However, over a 48-hour period following the administration of PCC and FFP, 76% of the patients in the PCC group and only 20% of the patients in the FFP group reached the INR target. Five (20%) patients in the PCC group received an additional dose of PCC, whereas 17 (68%) patients in the FFP group received a further dose of FFP (P=0.001). There was no significant difference between the two groups in Hb and Hct before and during a 48-hour period after PCC and FFP infusion. As regards safety monitoring and adverse drug reaction screening in the FFP group, the INR was high (INR > 2.5) in 86% of the patients. There was no report of hemorrhage in both groups. PCC reverses anticoagulation both effectively and safely while having the advantage of obviating the need to extra doses.

  18. The influence of the "cage" effect on the mechanism of reversible bimolecular multistage chemical reactions proceeding from different sites in solutions.

    Science.gov (United States)

    Doktorov, Alexander B

    2016-08-28

    Manifestations of the "cage" effect at the encounters of reactants have been theoretically treated on the example of multistage reactions (including bimolecular exchange reactions as elementary stages) proceeding from different active sites in liquid solutions. It is shown that for reactions occurring near the contact of reactants, consistent consideration of quasi-stationary kinetics of such multistage reactions (possible in the framework of the encounter theory only) can be made on the basis of chemical concepts of the "cage complex," just as in the case of one-site model described in the literature. Exactly as in the one-site model, the presence of the "cage" effect gives rise to new channels of reactant transformation that cannot result from elementary event of chemical conversion for the given reaction mechanism. Besides, the multisite model demonstrates new (as compared to one-site model) features of multistage reaction course.

  19. Reversible colour change in Arthropoda.

    Science.gov (United States)

    Umbers, Kate D L; Fabricant, Scott A; Gawryszewski, Felipe M; Seago, Ainsley E; Herberstein, Marie E

    2014-11-01

    The mechanisms and functions of reversible colour change in arthropods are highly diverse despite, or perhaps due to, the presence of an exoskeleton. Physiological colour changes, which have been recorded in 90 arthropod species, are rapid and are the result of changes in the positioning of microstructures or pigments, or in the refractive index of layers in the integument. By contrast, morphological colour changes, documented in 31 species, involve the anabolism or catabolism of components (e.g. pigments) directly related to the observable colour. In this review we highlight the diversity of mechanisms by which reversible colour change occurs and the evolutionary context and diversity of arthropod taxa in which it has been observed. Further, we discuss the functions of reversible colour change so far proposed, review the limited behavioural and ecological data, and argue that the field requires phylogenetically controlled approaches to understanding the evolution of reversible colour change. Finally, we encourage biologists to explore new model systems for colour change and to engage scientists from other disciplines; continued cross-disciplinary collaboration is the most promising approach to this nexus of biology, physics, and chemistry.

  20. Mechanics

    CERN Document Server

    Hartog, J P Den

    1961-01-01

    First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e

  1. Reverse current reduction of Ge photodiodes on Si without post-growth annealing Invited Paper

    Institute of Scientific and Technical Information of China (English)

    Sungbong Park; Shinya Takita; Yasuhiko; Ishikawa; Jiro Osaka; Kazumi Wada

    2009-01-01

    A new approach to reduce the reverse current of Ge pin photodiodes on Si is presented, in which an i-Si layer is inserted between Ge and top Si layers to reduce the electric field in the Ge layer. Without post- growth annealing, the reverse current density is reduced to ~10 mA/cm2 at -1 V, i.e., over one order of magnitude lower than that of the reference photodiode without i-Si layer. However, the responsivity of the photodiodes is not severely compromised. This lowered-reverse-current is explained by band-pinning at the i-Si/i-Ge interface. Barrier lowering mechanism induced by E-field is also discussed. The presented "non-thermal" approach to reduce reverse current should accelerate electronics-photonics convergence by using Ge on the Si complementary metal oxide semiconductor (CMOS) platform.

  2. Evolution of anthozoan polyp retraction mechanisms: convergent functional morphology and evolutionary allometry of the marginal musculature in order Zoanthidea (Cnidaria: Anthozoa: Hexacorallia).

    Science.gov (United States)

    Swain, Timothy D; Schellinger, Jennifer L; Strimaitis, Anna M; Reuter, Kim E

    2015-06-30

    Retraction is among the most important basic behaviors of anthozoan Cnidaria polyps and is achieved through the coordinated contraction of at least six different muscle groups. Across the Anthozoa, these muscles range from unrecognizable atrophies to massive hypertrophies, producing a wide diversity of retraction abilities and functional morphologies. The marginal musculature is often the single largest component of the retraction mechanism and is composed of a diversity of muscular, attachment, and structural features. Although the arrangements of these features have defined the higher taxonomy of Zoanthidea for more than 100 years, a decade of inferring phylogenies from nucleotide sequences has demonstrated fundamental misconceptions of their evolution. Here we expand the diversity of known marginal muscle forms from two to at least ten basic states and reconstruct the evolution of its functional morphology across the most comprehensive molecular phylogeny available. We demonstrate that the evolution of these forms follows a series of transitions that are much more complex than previously hypothesized and converge on similar forms multiple times. Evolution of the marginal musculature and its attachment and support structures are partially scaled according to variation in polyp and muscle size, but also vary through evolutionary allometry. Although the retraction mechanisms are diverse and their evolutionary histories complex, their morphologies are largely reflective of the evolutionary relationships among Zoanthidea higher taxa and may offer a key feature for integrative systematics. The convergence on similar forms across multiple linages of Zoanthidea mirrors the evolution of the marginal musculature in another anthozoan order (Actiniaria). The marginal musculature varies through evolutionary allometry of functional morphologies in response to requirements for additional force and resistance, and the specific ecological and symbiotic functions of individual

  3. Magnetic reversals from planetary dynamo waves

    DEFF Research Database (Denmark)

    Sheyko, Andrey; Finlay, Chris; Jackson, Andrew

    2016-01-01

    place in Earth's core, but the precise mechanism is debated. The majority of numerical geodynamo simulations that exhibit reversals operate in a regime in which the viscosity of the fluid remains important, and in which the dynamo mechanism primarily involves stretching and twisting of field lines...... by columnar convection. Here we present an example of another class of reversing-geodynamo model, which operates in a regime of comparatively low viscosity and high magnetic diffusivity. This class does not fit into the paradigm of reversal regimes that are dictated by the value of the local Rossby number...

  4. Studies on the growth, spectral, structural, electrical, optical and mechanical properties of Uronium 3-carboxy-4-hydroxybenzenesulfonate single crystal for third-order nonlinear optical applications

    Science.gov (United States)

    Silambarasan, A.; Krishna Kumar, M.; Thirunavukkarasu, A.; Md Zahid, I.; Mohan Kumar, R.; Umarani, P. R.

    2015-05-01

    Organic Uronium 3-carboxy-4-hydroxybenzenesulfonate (UCHBS) nonlinear optical single crystal was grown by solution growth technique. The solubility and nucleation studies were performed for UCHBS at different temperatures 30, 35, 40, 45, 50 and 55 °C. The crystal structure of UCHBS was elucidated from single crystal X-ray diffraction study. High resolution X-ray diffraction technique was employed to study the perfection and internal defects of UCHBS crystal. Infrared and Raman spectra were recorded to analyze the vibrational behavior of chemical bonds and its functional groups. The physico-chemical changes, stability and decomposition stages of the UCHBS compound were established by TG-DTA studies. The dielectric phenomenon of UCHBS crystal was studied at different temperatures with respect to frequency. Linear optical properties of transmittance, cut-off wavelength, band gap of UCHBS were found from UV-visible spectral studies. Third-order nonlinear optical susceptibility, nonlinear refractive index, nonlinear optical absorption coefficient values were measured by Z-scan technique. The mechanical properties of UCHBS crystal was studied by using Vicker's microhardness test. The growth features of UCHBS crystal were analyzed from etching studies.

  5. Third order optical non-linear (Z-scan), birefringence, photoluminescence, mechanical and etching studies on melaminium levulinate monohydrate (MLM) single crystal for optical device applications

    Science.gov (United States)

    Sivakumar, N.; Anbalagan, G.

    2016-10-01

    Z-scan studies on the grown crystal was investigated by diode-pumped Nd; YAG laser. Nonlinear refractive index (n2) and third-order nonlinear optical susceptibility (χ3) values of MLM were found to be -1.0 × 10-8 cm2/W and 1.36 × 10-6 esu respectively. Powder X-ray diffraction analysis depicted that the crystal belongs to monoclinic system with space group P21/c. Birefringence study revealed the optical dispersion behavior of MLM crystal. Linear refractive index on (10-1) plane was measured by prism coupling technique and was estimated to be 1.4705. Hardness study was carried out along three different planes which exhibit hardness anisotropy of 41.11%. Meyer's index values of the grown crystal for the (10-1), (010) and (111) planes were found to be 2.39, 2.61 and 2.04 respectively. Etching studies on the prominent (10-1) growth plane was explained by two dimensional layer growth mechanisms. Photoluminescence study was performed on MLM crystal to explore its efficacy towards optical device fabrications.

  6. Reversible order-disorder related band gap changes in Cu{sub 2}ZnSn(S,Se){sub 4} via post-annealing of solar cells measured by electroreflectance

    Energy Technology Data Exchange (ETDEWEB)

    Krämmer, Christoph; Huber, Christian; Zimmermann, Christian; Lang, Mario; Kalt, Heinz; Hetterich, Michael [Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany); Schnabel, Thomas; Ahlswede, Erik [Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), 70565 Stuttgart (Germany); Abzieher, Tobias [Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany); Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), 70565 Stuttgart (Germany)

    2014-12-29

    We report on order–disorder related band gap changes in Cu{sub 2}ZnSn(S,Se){sub 4} solar cells which are induced by post-annealing. The band gap changes of the absorber are detected utilizing electroreflectance and analyzed by comparison with predictions of the stochastic Vineyard model. This yields a critical temperature of T{sub C}=195 °C above which the Cu{sub 2}ZnSn(S,Se){sub 4} absorber layer is entirely disordered within the Cu–Zn layers of the kesterite unit cell. The temporal evolution of the band gap during annealing shows that the equilibrium value is reached on a timescale in the order of hours, depending on the annealing temperature. In contrast to other experimental techniques, electroreflectance precisely measures the band gap and is not influenced by defect-mediated radiative recombination.

  7. Reversal of benign prostate hyperplasia by selective occlusion of impaired venous drainage in the male reproductive system: novel mechanism, new treatment.

    Science.gov (United States)

    Gat, Y; Gornish, M; Heiblum, M; Joshua, S

    2008-10-01

    The prostate is an androgen-regulated exocrine gland producing over 30% of the noncellular components of the semen and promoting optimal conditions for survival and motility of sperm in the vagina. Benign prostate hyperplasia (BPH) is the most common benign neoplasm in men. Its aetiology is not clear, and therefore, current medical treatments are directed towards the symptoms. Though testosterone is known to be the promoter of prostate cell proliferation, no causal relation between serum testosterone levels and BPH has been found. In this study, we propose a novel and tested pathophysiological mechanism for the evolution of BPH and suggest a tested and effective treatment. We found that in all BPH patients, the one-way valves in the vertically oriented internal spermatic veins are destroyed (clinically manifested as varicocele), causing elevated hydrostatic pressure, some 6-fold greater than normal, in the venous drainage of the male reproductive system. The elevated pressure propagates to all interconnected vessels leading to a unique biological phenomenon: venous blood flows retrograde from the higher pressure in the testicular venous drainage system to the low pressure in the prostatic drainage system directly to the prostate (law of communicating vessels). We have found that free testosterone levels in this blood are markedly elevated, with a concentration of some 130-fold above serum level. Consequently, the prostate is exposed to: (i) increased venous pressure that causes hypertrophy; (ii) elevated concentration of free testosterone causing hyperplasia. We have treated 28 BPH patients using a technique that restores normal pressure in the venous drainage in the male reproductive system. The back-pressure and the back-flow of blood from the testicular to the prostate drainage system were eliminated and, consequently, a rapid reduction in prostate volume and a regression of prostate symptoms took place.

  8. Reverse design of transplanting mechanism with spatial planetary gear train based on spherical curve%基于球面曲线的空间非匀速行星轮系分插机构逆向设计

    Institute of Scientific and Technical Information of China (English)

    孙良; 祝建彬; 陈建能; 赵匀; 武传宇

    2014-01-01

    The transplanting mechanism is an end manipulator which picks seedlings from a seedling box and pushes them into a rice field. A wide-narrow distance mechanism is a kernel part of the rice transplanter to place seedlings in a wide row and narrow row alternation. Because of the spatial movement property of a bevel gear pair, and the requirement of variable speed transmission, a noncircular bevel gear was widely used in a wide-narrow transplanting mechanism design. On the condition of a determinate transmission scheme, how to obtain a sound planting trajectory and proper picking posture which is important for the wide-narrow distance transplanting mechanism to achieve upstanding and fewer damaged seedlings in planting work becomes a key issue. In general, putting forward a new mechanism, building a calculate model, and compiling a parameters optimization program are the three main steps for transplanting mechanism design. But there is some uncertainty of parameters-choosing and parameters effecting design goals in the design of the trajectory and planting paw posture in the traditional way. Furthermore, the special noncircular gear such as elliptical (or bevel) gears, eccentric-noncircular (or bevel) gears whose pitch curve are accessible to expression are often used in the transmission scheme design, which limits the formation of trajectory shape and planting paw posture. A new way to design a spatial planetary noncircular gear train by using reverse design methods was put forward based on the spherical curve. An ideal plane curve which is smooth, continuous, and closed was expressed by a free spline curve, and then a spherical curve was obtained by mapping the ideal plane curve onto the spherical surface with a preserved geodesic curvature. A two bar mechanism with three degrees of freedom was used to describe the spherical curve. According to the spatial geometric relationship between the two bars and the center of sphere, the transmission ratio model was

  9. Resolvin D1 reverses chronic pancreatitis-induced mechanical allodynia, phosphorylation of NMDA receptors, and cytokines expression in the thoracic spinal dorsal horn

    Directory of Open Access Journals (Sweden)

    Quan-Xin Feng

    2012-10-01

    Full Text Available Abstract Background We previously reported that immune activation in the spinal dorsal horn contributes to pain induced by chronic pancreatitis (CP. Targeting immune response in the CNS may provide effective treatments for CP-induced pain. Recent findings demonstrate that resolvin D1 (RvD1 can potently dampen inflammatory pain. We hypothesized that intrathecal injection of RvD1 may inhibit pain of CP. Methods Rat CP model was built through intrapancreatic infusion of trinitrobenzene sulfonic acid (TNBS. All the rats were divided into three groups: TNBS, sham, and naïve controls and were further divided for intrathecal RvD1 administration. Pain behavior of rats was tested with von Frey filaments. Anxiety-like behavior and free locomotor and exploration of rats were evaluated by open field test and elevated plus maze. Pancreatic histology was evaluated with hematoxylin and eosin staining. Phosphorylation of NMDA receptor and expression of inflammatory cytokines were examined with Western blot, real-time RT-PCR and ELISA. Results Behavioral study indicated that compared to the vehicle control, RvD1 (100 ng/kg significantly decreased TNBS-induced mechanical allodynia at 2 h after administration (response frequencies: 49.2 ± 3.7% vs 71.3 ± 6.1%, and this effect was dose-dependent. Neither CP nor RvD1 treatment could affect anxiety-like behavior. CP or RvD1 treatment could not affect free locomotor and exploration of rats. Western blot analysis showed that compared with that of naïve group, phosphorylated NR1 (pNR1 and pNR2B in TNBS rats were significantly increased in the spinal cord (pNR1: 3.87±0.31 folds of naïve control, pNR2B: 4.17 ± 0.24 folds of naïve control. Compared to vehicle control, 10 ng/kg of RvD1 could significantly block expressions of pNR1 (2.21 ± 0.26 folds of naïve and pNR2B (3.31 ± 0.34 folds of naïve. Real-time RT-PCR and ELISA data showed that RvD1 (10 ng/kg but not vehicle could significantly block expressions of

  10. Design and Experiment of 1LFQ-325 Pneumatic Reversible Plough

    Institute of Scientific and Technical Information of China (English)

    Xuan; ZHENG; Xuefeng; CHEN; Chaomin; QIN; Li; JIAbo; JIA

    2013-01-01

    A pneumatic reversible plough is developed, which complements to the tractor of 25.7-36.8 kW.The plough adopts the cylinder as reversing mechanism between the right and left plough bodies, and the cylinder can substitute the mechanical reversing mechanism. The pneumatic turnover allows the plough to be operated easily and turned over flexibly. Field experiment results show that indicators of plough performance meet the requirements of the relevant national standards.

  11. 反式twin-block治疗安氏Ⅲ类错牙合作用机理的研究%Mechanisms of Reverse Twin-block Appliance Therapy on Angle class Ⅲ Malocclusion

    Institute of Scientific and Technical Information of China (English)

    朱丽亚; 黄岩; 杨睿

    2014-01-01

    目的:通过治疗前后X线头颅定位侧位片的头影测量分析,得到反式Twin-block对生长发育期安氏Ⅲ类错(牙合)的治疗原理。方法选择替牙期、恒牙早期安氏Ⅲ类错牙合患者20例(男10例,女10例),平均年龄10岁8个月,全天戴用反式Twin-block矫治器治疗4.5-11个月。分别对治疗前后头颅定位侧位片进行头影测量。结果①上牙弓位置前移,上颌向前发育;②下颌向下后方向旋转;③上下颌牙齿发生代偿性移动。结论反式Twin-block可以有效矫治生长发育期安氏Ⅲ类错牙合,在患者侧面Ⅲ类骨面形得到明显改善的同时,牙齿发生代偿性移动。%Objective To assess the effect and mechanism of ClassⅢ malocclusions treatment with reverse Twin -block appliance.Methods Twenty subjects of ClassⅢ malocclusions were included in this study(10male,10 female).All patients were treated for all the day and for total of 4.5-11 months.The cephalometric re-cords of these subjects were examined before and after the treatments.The acquired data were processed with SPSS 10.0.Results①the reverse Twin-block could accel-erate the development of the maxillary bone .② the Mandibular showed a rotation of after the downward direction .③mandible teeth occurring compensatory move on . Conclusion Reverse Twin-block appliance could treat effectively angle classⅢ malocclusions.Patients had a significant improve in side of the form ,while the occur-rence of compensatory tooths movement .

  12. Reversible and Irreversible Time-Dependent Behavior of GRCop-84

    Science.gov (United States)

    Lerch, Bradley A.; Arnold, Steven M.; Ellis, David L.

    2017-01-01

    A series of mechanical tests were conducted on a high-conductivity copper alloy, GRCop-84, in order to understand the time dependent response of this material. Tensile, creep, and stress relaxation tests were performed over a wide range of temperatures, strain rates, and stress levels to excite various amounts of time-dependent behavior. At low applied stresses the deformation behavior was found to be fully reversible. Above a certain stress, termed the viscoelastic threshold, irreversible deformation was observed. At these higher stresses the deformation was observed to be viscoplastic. Both reversible and irreversible regions contained time dependent deformation. These experimental data are documented to enable characterization of constitutive models to aid in design of high temperature components.

  13. Word Order

    DEFF Research Database (Denmark)

    Rijkhoff, Jan

    2015-01-01

    The way constituents are ordered in a linguistic expression is determined by general principles and language specific rules. This article is mostly concerned with general ordering principles and the three main linguistic categories that are relevant for constituent order research: formal, functio...

  14. Thermostability of Cromobacterium viscosum lipase in AOT/isooctane reverse micelle.

    Science.gov (United States)

    Talukder, M M R; Zaman, M M; Hayashi, Y; Wu, J C; Kawanishi, T

    2007-04-01

    The thermostability of Cromobacterium viscosum lipase (EC 3.1.1.3) entrapped in AOT (sodium bis-[2-ethylhexyl] sulfosuccinate) reverse micelles was increased by the addition of short-chain polyethylene glycol (PEG 400). Two different approaches were considered: (1) the determination of half-life time and (2) the mechanistic analysis of deactivation kinetics. The half-life of lipase entrapped in AOT/isooctane reverse micelles with PEG 400 at 60 degrees C was 28 h, ninefold higher than that in reverse micelles without PEG 400. The lipase entrapped in both reverse micellar systems followed a series-type deactivation mechanism involving two first-order steps. The deactivation constant for the first step at 60 degrees C in PEG containing reverse micelles was 0.055 h!1, 11-fold lower than that in reverse micelles without PEG, whereas it remained almost constant for the second step. The inactivation energy of the lipase entrapped in reverse micelles with and without PEG 400 was 88.12 and 21.97 kJ/mol, respectively.

  15. Reversible cortical blindness: posterior reversible encephalopathy syndrome.

    Science.gov (United States)

    Bandyopadhyay, Sabyasachi; Mondal, Kanchan Kumar; Das, Somnath; Gupta, Anindya; Biswas, Jaya; Bhattacharyya, Subir Kumar; Biswas, Gautam

    2010-11-01

    Cortical blindness is defined as visual failure with preserved pupillary reflexes in structurally intact eyes due to bilateral lesions affecting occipital cortex. Bilateral oedema and infarction of the posterior and middle cerebral arterial territory, trauma, glioma and meningioma of the occipital cortex are the main causes of cortical blindness. Posterior reversible encephalopathy syndrome (PRES) refers to the reversible subtype of cortical blindness and is usually associated with hypertension, diabetes, immunosuppression, puerperium with or without eclampsia. Here, 3 cases of PRES with complete or partial visual recovery following treatment in 6-month follow-up are reported.

  16. Introduction to reversible computing

    CERN Document Server

    Perumalla, Kalyan S

    2013-01-01

    Few books comprehensively cover the software and programming aspects of reversible computing. Filling this gap, Introduction to Reversible Computing offers an expanded view of the field that includes the traditional energy-motivated hardware viewpoint as well as the emerging application-motivated software approach. Collecting scattered knowledge into one coherent account, the book provides a compendium of both classical and recently developed results on reversible computing. It explores up-and-coming theories, techniques, and tools for the application of rever

  17. Reversible Logic Circuit Synthesis

    CERN Document Server

    Shende, V V; Markov, I L; Prasad, A K; Hayes, John P.; Markov, Igor L.; Prasad, Aditya K.; Shende, Vivek V.

    2002-01-01

    Reversible, or information-lossless, circuits have applications in digital signal processing, communication, computer graphics and cryptography. They are also a fundamental requirement for quantum computation. We investigate the synthesis of reversible circuits that employ a minimum number of gates and contain no redundant input-output line-pairs (temporary storage channels). We propose new constructions for reversible circuits composed of NOT, Controlled-NOT, and TOFFOLI gates (the CNT gate library) based on permutation theory. A new algorithm is given to synthesize optimal reversible circuits using an arbitrary gate library. We also describe much faster heuristic algorithms. We also pursue applications of the proposed techniques to the synthesis of quantum circuits.

  18. Establishing the reliability of test procedures in order to investigate the effect of penetrating trunk trauma and prolonged mechanical ventilation on the recovery of adult survivors

    Directory of Open Access Journals (Sweden)

    H. van Aswegen

    2007-02-01

    Full Text Available Gunshot wounds and/or stab wounds to the trunk are injuries commonly seen in South African hospitals. Such injuries often necessitate exploratory surgical intervention to identify and treat injuries to the internal organs. These patients are managed in the intensive care unit and often undergo prolonged mechanical ventilation with immobilization that often results in some degree of muscle dysfunction. In order to monitor the recovery of adult survivors over a 6-month period after hospital discharge, validation ofthe six-minute walk test and hand-held dynamometry between datacollectors was necessary.Methods: Data was collected for the six-minute walk test andhand-held dynamometry by three data collectors.  Subsequently a correlation coefficient (Pearson product momentcorrelate was calculated and one-way analysis of variance (ANOVA performed to assess the degree of associationbetween the data.Results and Discussion: A strong positive correlation existed for data collected on the 6-minute walk test betweendata collectors 1, 2 and 3 with r ranging from 0.71 to 1  (p < 0.025 to p < 0.0005. The intra-class correlation (ICCscores between data collectors ranged from 0.69 to 0.90 confirming this finding.  A weak to fair correlation existedbetween data collectors for dynamometry measurements of the triceps and quadriceps muscles. Intra-class correlationscores ranged from 0.11 to 0.71.Conclusion: A strongly positive inter-observer correlation existed for data sets for the six-minute walk test. A weakintra-observer correlation existed for data sets collected by data collectors for dynamometry however this improvedwith intervention. The degree of association between data sets for dynamometry should be assessed again during themain study.

  19. Reversible and irreversible higher-order cycloaddition reactions of polyolefins with a multiple-bonded heavier group 13 alkene analogue: contrasting the behavior of systems with π-π, π-π*, and π-n+ frontier molecular orbital symmetry.

    Science.gov (United States)

    Caputo, Christine A; Guo, Jing-Dong; Nagase, Shigeru; Fettinger, James C; Power, Philip P

    2012-04-25

    The heavier group 13 element alkene analogue, digallene Ar(iPr(4))GaGaAr(iPr(4)) (1) [Ar(iPr(4)) = C(6)H(3)-2,6-(C(6)H(3)-2,6-(i)Pr(2))(2)], has been shown to react readily in [n + 2] (n = 6, 4, 2 + 2) cycloaddition reactions with norbornadiene and quadricyclane, 1,3,5,7-cyclooctatetraene, 1,3-cyclopentadiene, and 1,3,5-cycloheptatriene to afford the heavier element deltacyclane species Ar(iPr(4))Ga(C(7)H(8))GaAr(iPr(4)) (2), pseudoinverse sandwiches Ar(iPr(4))Ga(C(8)H(8))GaAr(iPr(4)) (3, 3(iso)), and polycyclic compounds Ar(iPr(4))Ga(C(5)H(6))GaAr(iPr(4)) (4) and Ar(iPr(4))Ga(C(7)H(8))GaAr(iPr(4)) (5, 5(iso)), respectively, under ambient conditions. These reactions are facile and may be contrasted with other all-carbon versions, which require transition-metal catalysis or forcing conditions (temperature, pressure), or with the reactions of the corresponding heavier group 14 species Ar(iPr(4))EEAr(iPr(4)) (E = Ge, Sn), which give very different product structures. We discuss several mechanistic possibilities, including radical- and non-radical-mediated cyclization pathways. These mechanisms are consistent with the improved energetic accessibility of the LUMO of the heavier group 13 element multiple bond in comparison with that of a simple alkene or alkyne. We show that the calculated frontier molecular orbitals (FMOs) of Ar(iPr(4))GaGaAr(iPr(4)) are of π-π symmetry, allowing this molecule to engage in a wider range of reactions than permitted by the usual π-π* FMOs of C-C π bonds or the π-n(+) FMOs of heavier group 14 alkyne analogues.

  20. Reverse Core Engine with Thrust Reverser

    Science.gov (United States)

    Suciu, Gabriel L. (Inventor); Chandler, Jesse M. (Inventor)

    2017-01-01

    An engine system has a gas generator, a bi-fi wall surrounding at least a portion of the gas generator, a casing surrounding a fan, and the casing having first and second thrust reverser doors which in a deployed position abut each other and the bi-fi wall.

  1. Parallelization of Reversible Ripple-carry Adders

    DEFF Research Database (Denmark)

    Thomsen, Michael Kirkedal; Axelsen, Holger Bock

    2009-01-01

    The design of fast arithmetic logic circuits is an important research topic for reversible and quantum computing. A special challenge in this setting is the computation of standard arithmetical functions without the generation of \\emph{garbage}. Here, we present a novel parallelization scheme...... wherein $m$ parallel $k$-bit reversible ripple-carry adders are combined to form a reversible $mk$-bit \\emph{ripple-block carry adder} with logic depth $\\mathcal{O}(m+k)$ for a \\emph{minimal} logic depth $\\mathcal{O}(\\sqrt{mk})$, thus improving on the $mk$-bit ripple-carry adder logic depth $\\mathcal......{O}(m\\cdot k)$. The underlying mechanisms of the parallelization scheme are formally proven correct. We also show designs for garbage-less reversible comparison circuits. We compare the circuit costs of the resulting ripple-block carry adder with known optimized reversible ripple-carry adders in measures...

  2. Flow reversals in thermally driven turbulence

    CERN Document Server

    Sugiyama, Kazuyasu; Stevens, Richard J A M; Chan, Tak Shing; Zhou, Sheng-Qi; Xi, Heng-Dong; Sun, Chao; Grossmann, Siegfried; Xia, Ke-Qing; Lohse, Detlef; 10.1103/PhysRevLett.105.034503

    2011-01-01

    We analyze the reversals of the large scale flow in Rayleigh-B\\'enard convection both through particle image velocimetry flow visualization and direct numerical simulations (DNS) of the underlying Boussinesq equations in a (quasi) two-dimensional, rectangular geometry of aspect ratio 1. For medium Prandtl number there is a diagonal large scale convection roll and two smaller secondary rolls in the two remaining corners diagonally opposing each other. These corner flow rolls play a crucial role for the large scale wind reversal: They grow in kinetic energy and thus also in size thanks to plume detachments from the boundary layers up to the time that they take over the main, large scale diagonal flow, thus leading to reversal. Based on this mechanism we identify a typical time scale for the reversals. We map out the Rayleigh number vs Prandtl number phase space and find that the occurrence of reversals very sensitively depends on these parameters.

  3. 松软突出煤层水平钻孔反循环气力排屑机理%Chip removal mechanism by air reverse circulation during horizontal drilling in soft outburst coal seam

    Institute of Scientific and Technical Information of China (English)

    韩晓明; 张龙列; 刘瑜; 铁占续

    2015-01-01

    In order to solve the problem of difficult hole-making in gas drainage during bedding drilling process , a new technology of chip removal by air reverse circulation through the drill rod bore during the gas drainage drilling in soft outburst coal seam was put forward .The mathematical model of air reverse circulation conveying on coal cut-tings particles in rod bore was established , and the variation laws of conveying pressure loss and solid phase velocity were analyzed by simulation .The results showed that under the effect of air reverse circulation in the process of bedding horizontal drilling , the air velocity in the upper part of drill rod bore is relatively stable , while in the under part of drill rod bore , the air velocity close to the wall decreases significantly and is less than that in the central zone .In the same location the air velocity becomes greater with the increase of conveying concentration .Under dif-ferent conveying concentration , the pressure loss in the drill rod bore reduces and then increases with the increase of conveying air velocity .There exists a best economic speed in chip removal by air reverse circulation through the drill rod bore .%为了解决顺层钻进瓦斯抽放钻孔成孔难的问题,提出了松软突出煤层瓦斯抽放钻孔钻杆内孔反循环气力排屑新技术,建立煤屑颗粒在钻杆内孔的反循环气力输送数学模型,经仿真求解,分析了输送压力损失及固相速度的变化规律。结果表明,在顺层水平钻孔钻进过程中,煤屑在反循环气力作用下,气流速度在钻杆内孔中上部比较稳定,而在钻杆内孔下部靠近内壁处的气流速度明显下降且小于中心区域;在同一位置输送浓度越大,气流速度也越大;在输送浓度不同的情况下,随着输送气流速度的增加,钻杆内孔的压力损失先降低再增高,在钻杆内孔反循环气力排屑时存在最佳经济速度。

  4. Order, Disorder and Confinement

    CERN Document Server

    D'Elia, M; Pica, C

    2006-01-01

    Studying the order of the chiral transition for $N_f=2$ is of fundamental importance to understand the mechanism of color confinement. We present results of a numerical investigation on the order of the transition by use of a novel strategy in finite size scaling analysis. The specific heat and a number of susceptibilities are compared with the possible critical behaviours. A second order transition in the O(4) and O(2) universality classes are excluded. Substantial evidence emerges for a first order transition. Results are in agreement with those found by studying the scaling properties of a disorder parameter related to the dual superconductivity mechanism of color confinement.

  5. Mechanics

    CERN Document Server

    Chester, W

    1979-01-01

    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  6. Quantum reverse hypercontractivity

    Energy Technology Data Exchange (ETDEWEB)

    Cubitt, Toby [Department of Computer Science, University College London, London, United Kingdom and Centre for Quantum Information and Foundations, DAMTP, University of Cambridge, Cambridge (United Kingdom); Kastoryano, Michael [NBIA, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen (Denmark); Montanaro, Ashley [School of Mathematics, University of Bristol, Bristol (United Kingdom); Temme, Kristan [Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125 (United States)

    2015-10-15

    We develop reverse versions of hypercontractive inequalities for quantum channels. By generalizing classical techniques, we prove a reverse hypercontractive inequality for tensor products of qubit depolarizing channels. We apply this to obtain a rapid mixing result for depolarizing noise applied to large subspaces and to prove bounds on a quantum generalization of non-interactive correlation distillation.

  7. Clocked Thrust Reversers

    Science.gov (United States)

    Suciu, Gabriel L. (Inventor); Chandler, Jesse M. (Inventor)

    2017-01-01

    An aircraft includes a fuselage including a propulsion system supported within an aft portion. A thrust reverser is mounted proximate to the propulsion system for directing thrust in a direction to slow the aircraft. The thrust reverser directs thrust at an angle relative to a vertical plane to reduce interference on control surfaces and reduce generation of underbody lift.

  8. Atrioventricular Pacemaker Lead Reversal

    Directory of Open Access Journals (Sweden)

    Mehmet K Aktas, MD

    2007-01-01

    Full Text Available During cardiac surgery temporary epicardial atrial and ventricular leads are placed in case cardiac pacing is required postoperatively. We present the first reported series of patients with reversal of atrioventricular electrodes in the temporary pacemaker without any consequent deleterious hemodynamic effect. We review the electrocardiographic findings and discuss the findings that lead to the discovery of atrioventricular lead reversal.

  9. Reversible cerebral vasoconstriction syndrome

    Directory of Open Access Journals (Sweden)

    Saini Monica

    2009-01-01

    Full Text Available Reversible cerebral vasoconstriction syndromes (RCVS are a group of disorders that have in common an acute presentation with headache, reversible vasoconstriction of cerebral arteries, with or without neurological signs and symptoms. In contrast to primary central nervous system vasculitis, they have a relatively benign course. We describe here a patient who was diagnosed with RCVS.

  10. Reversible Watermarking Using Statistical Information

    Directory of Open Access Journals (Sweden)

    Kurugollu Fatih

    2010-01-01

    Full Text Available In most reversible watermarking methods, a compressed location map is exploited in order to ensure reversibility. Besides, in some methods, a header containing critical information is appended to the payload for the extraction and recovery process. Such schemes have a highly fragile nature; that is, changing a single bit in watermarked data may prohibit recovery of the original host as well as the embedded watermark. In this paper, we propose a new scheme in which utilizing a compressed location map is completely removed. In addition, the amount of auxiliary data is decreased by employing the adjacent pixels information. Therefore, in addition to quality improvement, independent authentication of different regions of a watermarked image is possible.

  11. Molecular Simulation of Reverse Micelles

    Science.gov (United States)

    Chowdhary, Janamejaya; Ladanyi, Branka

    2009-03-01

    Reverse micelles (RM) are surfactant assemblies containing a nanosized water pool dissolved in a hydrophobic solvent. Understanding their properties is crucial for insight into the effect of confinement on aqueous structure, dynamics as well as physical processes associated with solutes in confinement. We perform molecular dynamics simulations for the RM formed by the surfactant Aerosol-OT (AOT) in isooctane (2,2,4-trimethyl pentane) in order to study the effect of reverse micelle size on the aqueous phase. The structure of the RM is quantified in terms of the radial and pair density distributions. Dynamics are studied in terms of the mean squared displacements and various orientational time correlation functions in different parts of the RM so as to understand the effect of proximity to the interface on aqueous dynamics. Shape fluctuations of the RM are also analyzed.

  12. Performance of the reverse Helmbold universal portfolio

    Science.gov (United States)

    Tan, Choon Peng; Kuang, Kee Seng; Lee, Yap Jia

    2017-04-01

    The universal portfolio is an important investment strategy in a stock market where no stochastic model is assumed for the stock prices. The zero-gradient set of the objective function estimating the next-day portfolio which contains the reverse Kullback-Leibler order-alpha divergence is considered. From the zero-gradient set, the explicit, reverse Helmbold universal portfolio is obtained. The performance of the explicit, reverse Helmbold universal portfolio is studied by running them on some stock-price data sets from the local stock exchange. It is possible to increase the wealth of the investor by using these portfolios in investment.

  13. Test of time reversal invariance with TRINE

    CERN Document Server

    Soldner, T; Schreckenbach, K; Bussière, A; Kossakowski, R; Liaud, P; Zimmer, O

    2000-01-01

    The new detector TRINE (time reversal invariance neutron experiment) was developed to test the time reversal invariance in the neutron decay. The precision of former experiments can be improved by one order of magnitude with an improved proton detection, a better background suppression and an angular resolving measurement using multiwire proportional chambers in coincidence with plastic scintillators, and the higher neutron flux and polarization available today. The concept of the detector and the status of the project is discussed.

  14. Test of time reversal invariance with TRINE

    Energy Technology Data Exchange (ETDEWEB)

    Soldner, T.; Beck, L.; Schreckenbach, K.; Bussiere, A.; Kossakowski, R.; Liaud, P.; Zimmer, O

    2000-02-11

    The new detector TRINE (time reversal invariance neutron experiment) was developed to test the time reversal invariance in the neutron decay. The precision of former experiments can be improved by one order of magnitude with an improved proton detection, a better background suppression and an angular resolving measurement using multiwire proportional chambers in coincidence with plastic scintillators, and the higher neutron flux and polarization available today. The concept of the detector and the status of the project is discussed.

  15. The relative abundances of resolved l2CH2D2 and 13CH3D and mechanisms controlling isotopic bond ordering in abiotic and biotic methane gases

    Science.gov (United States)

    Young, E. D.; Kohl, I. E.; Lollar, B. Sherwood; Etiope, G.; Rumble, D.; Li (李姝宁), S.; Haghnegahdar, M. A.; Schauble, E. A.; McCain, K. A.; Foustoukos, D. I.; Sutclife, C.; Warr, O.; Ballentine, C. J.; Onstott, T. C.; Hosgormez, H.; Neubeck, A.; Marques, J. M.; Pérez-Rodríguez, I.; Rowe, A. R.; LaRowe, D. E.; Magnabosco, C.; Yeung, L. Y.; Ash, J. L.; Bryndzia, L. T.

    2017-04-01

    We report measurements of resolved 12CH2D2 and 13CH3D at natural abundances in a variety of methane gases produced naturally and in the laboratory. The ability to resolve 12CH2D2 from 13CH3D provides unprecedented insights into the origin and evolution of CH4. The results identify conditions under which either isotopic bond order disequilibrium or equilibrium are expected. Where equilibrium obtains, concordant Δ12CH2D2 and Δ13CH3D temperatures can be used reliably for thermometry. We find that concordant temperatures do not always match previous hypotheses based on indirect estimates of temperature of formation nor temperatures derived from CH4/H2 D/H exchange, underscoring the importance of reliable thermometry based on the CH4 molecules themselves. Where Δ12CH2D2 and Δ13CH3D values are inconsistent with thermodynamic equilibrium, temperatures of formation derived from these species are spurious. In such situations, while formation temperatures are unavailable, disequilibrium isotopologue ratios nonetheless provide novel information about the formation mechanism of the gas and the presence or absence of multiple sources or sinks. In particular, disequilibrium isotopologue ratios may provide the means for differentiating between methane produced by abiotic synthesis vs. biological processes. Deficits in 12CH2D2 compared with equilibrium values in CH4 gas made by surface-catalyzed abiotic reactions are so large as to point towards a quantum tunneling origin. Tunneling also accounts for the more moderate depletions in 13CH3D that accompany the low 12CH2D2 abundances produced by abiotic reactions. The tunneling signature may prove to be an important tracer of abiotic methane formation, especially where it is preserved by dissolution of gas in cool hydrothermal systems (e.g., Mars). Isotopologue signatures of abiotic methane production can be erased by infiltration of microbial communities, and Δ12CH2D2 values are a key tracer of microbial recycling.

  16. Time reversibility, computer simulation, and chaos

    CERN Document Server

    Hoover, William Graham

    1999-01-01

    A small army of physicists, chemists, mathematicians, and engineers has joined forces to attack a classic problem, the "reversibility paradox", with modern tools. This book describes their work from the perspective of computer simulation, emphasizing the author's approach to the problem of understanding the compatibility, and even inevitability, of the irreversible second law of thermodynamics with an underlying time-reversible mechanics. Computer simulation has made it possible to probe reversibility from a variety of directions and "chaos theory" or "nonlinear dynamics" has supplied a useful

  17. Time reversibility in the quantum frame

    Energy Technology Data Exchange (ETDEWEB)

    Masot-Conde, Fátima [Escuela Superior Ingenieros, Dpt. Física Aplicada III, Universidad de Sevilla Isla Mágica, 41092- Sevilla (Spain)

    2014-12-04

    Classic Mechanics and Electromagnetism, conventionally taken as time-reversible, share the same concept of motion (either of mass or charge) as the basis of the time reversibility in their own fields. This paper focuses on the relationship between mobile geometry and motion reversibility. The goal is to extrapolate the conclusions to the quantum frame, where matter and radiation behave just as elementary mobiles. The possibility that the asymmetry of Time (Time’s arrow) is an effect of a fundamental quantum asymmetry of elementary particles, turns out to be a consequence of the discussion.

  18. Modeling the amorphous structure of mechanically alloyed Ti{sub 50}Ni{sub 25}Cu{sub 25} using anomalous wide-angle x-ray scattering and reverse Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lima, J.C. de, E-mail: fsc1jcd@fisica.ufsc.br [Departamento de Física, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Poffo, C.M. [Departamento de Engenharia Mecânica, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Souza, S.M. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Machado, K.D. [Departamento de Física, Centro Politécnico, Universidade Federal do Paraná, 81531-990 Curitiba, Paraná (Brazil); Trichês, D.M. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Grandi, T.A. [Departamento de Física, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Biasi, R.S. de [Seção de Engenharia Mecânica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil)

    2013-09-01

    An amorphous Ti{sub 50}Ni{sub 25}Cu{sub 25} alloy was produced by 19 h of mechanical alloying. Anomalous wide angle x-ray scattering data were collected at six energies and six total scattering factors were obtained. By considering the data collected at two energies close to the Ni and Cu K edges, two differential anomalous scattering factors about the Ni and Cu atoms were obtained, showing that the chemical environments around these atoms are different. Eight factors were used as input data to the reverse Monte Carlo method used to compute the partial structure factors S{sub Ti3Ti}(K), S{sub Ti–Cu}(K), S{sub Ti–Ni}(K), S{sub Cu3Cu}(K), S{sub Cu–Ni}(K) and S{sub Ni–Ni}(K) and the partial pair distribution functions G{sub Ti3Ti}(r), G{sub Ti–Cu}(r), G{sub Ti–Ni}(r), G{sub Cu3Cu}(r), G{sub Cu–Ni}(r) and G{sub Ni–Ni}(r). From the RMC final atomic configuration and G{sub ij}(r) functions, the coordination numbers and interatomic atomic distances for the first neighbors were determined.

  19. 脂肪酸逆转局麻药心肌毒性的药理机制研究进展%Progress in Pharmacological Mechanism for the Role of Fatty Acid in Reversal of Myocardial Toxicity of Local Anesthetics

    Institute of Scientific and Technical Information of China (English)

    高晶; 刘超

    2014-01-01

    目前尚没有特异的局麻药解毒剂,严重阻碍了临床治疗效果,寻找有效的局麻药解毒剂日益紧迫。本文从脂肪池、能量代谢、NO、离子通道和增溶作用来诠释脂肪酸逆转局麻药心肌毒性的分子药理学机制,并比较了纳米脂质体与普通脂肪乳剂结构和功能上的不同的特点。%At present, there is no specific antidote for local anesthetic toxicity, which seriously hindered therapeutic efficts of clinical treatment. It is increasingly urgent for finding find the effective antidote to local anesthetic. This article at-tempts to interpret the molecular pharmacological mechanism from fat pool, energy metabolism, NO, ion channel and solubili-zation for the role of fatty acids in reversal of myocardial toxicity of local anesthetics. And the different characteristics of the structure and function of nano liposome and fat emulsion were compared.

  20. 基于随机需求与回收的逆向供应链奖惩机制%Premium and penalty mechanism of reverse supply chain with stochastic demand and collection

    Institute of Scientific and Technical Information of China (English)

    曹柬; 胡强; 楼婷渊; 周根贵

    2012-01-01

    针对由制造商、加工商和回收商构成的三级逆向供应链系统,基于博弈理论建立了需求与回收双重不确定环境下以制造商为领导者的Stackelberg模型。设计了制造商与加工商、加工商与回收商之间的目标奖惩合同,结合实践提出了逆向供应链运作中四种不同的成员问的奖惩激励方式,比较分析了各种奖惩方式对系统最优决策的影响。采用数值仿真讨论了各类参数与逆向供应链成员期望利润之间的关系。研究结论对逆向供应链的运营实践具有很好的现实指导意义。%For the three-level Reverse Supply Chain( RSC) system including a manufacturer, a processor and a collec- tor, a manufacturer-leading Staekelberg model was established with uncertainties of both demand and collection based on game theory. The premium and penalty contracts between manufacturer and processor, processor and col- lector were designed separately. Combined with actual operation situation, four kinds of premium and penalty incen- tive mechanisms in RSC operation were proposed, and influences of proposed mechanisms to the optimal strategies of RSC were discussed. The relationships between the members' expected profits and various parameters were dis- cussed by numerical simulation. The conclusions were helpful to guide the actual operation of RSC.

  1. An algebra of reversible computation

    OpenAIRE

    2016-01-01

    We design an axiomatization for reversible computation called reversible ACP (RACP). It has four extendible modules, basic reversible processes algebra (BRPA), algebra of reversible communicating processes (ARCP), recursion and abstraction. Just like process algebra ACP in classical computing, RACP can be treated as an axiomatization foundation for reversible computation.

  2. An Algebra of Reversible Computation

    OpenAIRE

    Yong WANG

    2014-01-01

    We design an axiomatization for reversible computation called reversible ACP (RACP). It has four extendible modules, basic reversible processes algebra (BRPA), algebra of reversible communicating processes (ARCP), recursion and abstraction. Just like process algebra ACP in classical computing, RACP can be treated as an axiomatization foundation for reversible computation.

  3. An algebra of reversible computation.

    Science.gov (United States)

    Wang, Yong

    2016-01-01

    We design an axiomatization for reversible computation called reversible ACP (RACP). It has four extendible modules: basic reversible processes algebra, algebra of reversible communicating processes, recursion and abstraction. Just like process algebra ACP in classical computing, RACP can be treated as an axiomatization foundation for reversible computation.

  4. Bubbler: A Novel Ultra-High Power Density Energy Harvesting Method Based on Reverse Electrowetting

    OpenAIRE

    Tsung-Hsing Hsu; Supone Manakasettharn; J. Ashley Taylor; Tom Krupenkin

    2015-01-01

    We have proposed and successfully demonstrated a novel approach to direct conversion of mechanical energy into electrical energy using microfluidics. The method combines previously demonstrated reverse electrowetting on dielectric (REWOD) phenomenon with the fast self-oscillating process of bubble growth and collapse. Fast bubble dynamics, used in conjunction with REWOD, provides a possibility to increase the generated power density by over an order of magnitude, as compared to the REWOD alon...

  5. Reversible Data Hiding Techniques

    Directory of Open Access Journals (Sweden)

    Dhananjay Yadav

    2012-03-01

    Full Text Available Reversible data hiding is a technique that is used to hide data inside an image. The data is hidden in such a way that the exact or original data is not visible. The hidden data can be retrieved as and when required. There are several methods that are used in reversible data hiding techniques like Watermarking, Lossless embedding and encryption. In this paper we present a review of reversible watermarking techniques and show different methods that are used to get reversible data hiding technique with higher embedding capacity and invisible objects. Watermark need not be hidden. Watermarking can be applied to 1. Images, 2. Text, 3. Audio/video, 4. Software.

  6. Reversible flowchart languages and the structured reversible program theorem

    DEFF Research Database (Denmark)

    Yokoyama, Tetsuo; Axelsen, Holger Bock; Glück, Robert

    2008-01-01

    Many irreversible computation models have reversible counterparts, but these are poorly understood at present. We introduce reversible flowcharts with an assertion operator and show that any reversible flowchart can be simulated by a structured reversible flowchart using only three control flow o...... justification for low-level machine code for reversible microprocessors as well as high-level block-structured reversible languages. We give examples for both such languages and illustrate them with a lossless encoder for permutations given by Dijkstra....

  7. Thermo-mechanical interaction effects in foam cored sandwich panels-correlation between High-order models and Finite element analysis results

    DEFF Research Database (Denmark)

    Palleti, Hara Naga Krishna Teja; Santiuste, Carlos; Thomsen, Ole Thybo;

    2010-01-01

    Thermo-mechanical interaction effects including thermal material degradation in polymer foam cored sandwich structures is investigated using the commercial Finite Element Analysis (FEA) package ABAQUS/Standard. Sandwich panels with different boundary conditions in the form of simply supported...

  8. Adaptive Pairing Reversible Watermarking.

    Science.gov (United States)

    Dragoi, Ioan-Catalin; Coltuc, Dinu

    2016-05-01

    This letter revisits the pairwise reversible watermarking scheme of Ou et al., 2013. An adaptive pixel pairing that considers only pixels with similar prediction errors is introduced. This adaptive approach provides an increased number of pixel pairs where both pixels are embedded and decreases the number of shifted pixels. The adaptive pairwise reversible watermarking outperforms the state-of-the-art low embedding bit-rate schemes proposed so far.

  9. Novel Designs of Quantum Reversible Counters

    Science.gov (United States)

    Qi, Xuemei; Zhu, Haihong; Chen, Fulong; Zhu, Junru; Zhang, Ziyang

    2016-11-01

    Reversible logic, as an interesting and important issue, has been widely used in designing combinational and sequential circuits for low-power and high-speed computation. Though a significant number of works have been done on reversible combinational logic, the realization of reversible sequential circuit is still at premature stage. Reversible counter is not only an important part of the sequential circuit but also an essential part of the quantum circuit system. In this paper, we designed two kinds of novel reversible counters. In order to construct counter, the innovative reversible T Flip-flop Gate (TFG), T Flip-flop block (T_FF) and JK flip-flop block (JK_FF) are proposed. Based on the above blocks and some existing reversible gates, the 4-bit binary-coded decimal (BCD) counter and controlled Up/Down synchronous counter are designed. With the help of Verilog hardware description language (Verilog HDL), these counters above have been modeled and confirmed. According to the simulation results, our circuits' logic structures are validated. Compared to the existing ones in terms of quantum cost (QC), delay (DL) and garbage outputs (GBO), it can be concluded that our designs perform better than the others. There is no doubt that they can be used as a kind of important storage components to be applied in future low-power computing systems.

  10. Analysis of fruit and oil quantity and quality distribution in high-density olive trees in order to improve the mechanical harvesting process

    Energy Technology Data Exchange (ETDEWEB)

    Castillo-Ruiz, F. J.; Jiménez-Jiménez, F.; Blanco-Roldán, G.L.; Sola-Guirado, R. R.; Agüera-Vega, J.; Castro-Garcia, S.

    2015-07-01

    Olive fruit production and oil quality distribution with respect to canopy distribution are important criteria for selection and improvement of mechanical harvesting methods. Tests were performed in a high-density olive orchard (Olea europea L., cv. Arbequina) in southern Spain. Fruit distribution, fruit properties and oil parameters were measured by taken separate samples for each canopy location and tree. Results showed a high percentage of fruits and oil located in the middle-outer and upper canopy, representing more than 60% of total production. The position of these fruits along with their higher weight per fruit, maturity index and polyphenol content make them the target for all mechanical harvesting systems. The fruits from the lower canopy represented close to 30% of fruit and oil production, however, the mechanical harvesting of these fruits is inefficient for mechanical harvesting systems. Whether these fruits cannot be properly harvested, enhance tree training to raise their position is recommended. Fruits located inside the canopy are not a target location for mechanical harvesting systems as they were a small percentage of the total fruit (<10%). Significant differences were found for polyphenol content with respect to canopy height, although this was not the case with acidity. In addition, the ripening index did not influence polyphenol content and acidity values within the canopy. Fruit production, properties and oil quality varied depending on fruit canopy position. Thus harvesting systems may be targeted at maximize harvesting efficiency including an adequate tree training system adapted to the harvesting system. (Author)

  11. On thermodynamic and microscopic reversibility

    Energy Technology Data Exchange (ETDEWEB)

    Crooks, Gavin E.

    2011-07-12

    The word 'reversible' has two (apparently) distinct applications in statistical thermodynamics. A thermodynamically reversible process indicates an experimental protocol for which the entropy change is zero, whereas the principle of microscopic reversibility asserts that the probability of any trajectory of a system through phase space equals that of the time reversed trajectory. However, these two terms are actually synonymous: a thermodynamically reversible process is microscopically reversible, and vice versa.

  12. LQR Controller for Toroidal Continuously Variable Transmission in Reverse Motion

    Science.gov (United States)

    Mensler, Michel; Kawabe, Taketoshi; Joe, Shinichiro

    The system considered in this paper is a Toroidal Continuously Variable Transmission (TCVT) system for cars. This system is unstable in reverse motion as some mechanical parts have been removed from the original one for cost reduction, and the gear ratio has to be regulated around its nominal value for car reverse motion. The control theory used here is the Linear Quadratic Regulator (LQR) associated to a gain-scheduling technique, as the TCVT system is nonlinear according to the car speed. Moreover, as the LQR method requires the entire TCVT state vector and as the only available signal is the gear ratio, a full-order observer is designed. In order to take the other nonlinearities of the system into account, the observer is nonlinear: a diffeomorphism is then used for converting the variables provided by the nonlinear observer into the needed variables. In order to verify the effectiveness and the robustness of the controller against the car speed and the torque shift disturbance phenomenon, several experiments with a test-bed and with an actual vehicle have been performed and showed the efficiency of the proposed controller.

  13. 反序律B{1,2,i}A{1,2,i}=(AB){1,2,i}i=3,4成立的充要条件%Necessary and sufficient conditions for reverse order laws B{1,2,i}A { 1,2,i} (∈)(AB){1,2,i},i=3,4

    Institute of Scientific and Technical Information of China (English)

    孙萍; 孟令胜

    2011-01-01

    证明两个矩阵乘积的{1,2,3}-逆和{1,2,4}-逆反序律包含关系B{1,2,i}A{1,2,i}(∈)(AB){1,2,i},i=3,4分别等价干等式反序律B{1,2,i}A{1,2,i}=(AB){1,2,i},i=3,4.从而得到上述等式反序律成立的充要条件.%It was verified that the inclusion relationship B{1,2,i}A{1,2,i} (∈)(AB){1,2,i}, i= 3,4 for reverse order laws of {1,2,3}-inverse and {1,2,4}- inverse of the product of two matrixes was respectively equivalent to the identical reverse order laws B{1,2,i}A{1,2,i}=(AB){1,2,i}, i=3,4, so that the necessary and sufficient conditions were obtained for holding the foregoing identical reverse order laws.

  14. Reverse preferential spread in complex networks

    Science.gov (United States)

    Toyoizumi, Hiroshi; Tani, Seiichi; Miyoshi, Naoto; Okamoto, Yoshio

    2012-08-01

    Large-degree nodes may have a larger influence on the network, but they can be bottlenecks for spreading information since spreading attempts tend to concentrate on these nodes and become redundant. We discuss that the reverse preferential spread (distributing information inversely proportional to the degree of the receiving node) has an advantage over other spread mechanisms. In large uncorrelated networks, we show that the mean number of nodes that receive information under the reverse preferential spread is an upper bound among any other weight-based spread mechanisms, and this upper bound is indeed a logistic growth independent of the degree distribution.

  15. Docking mode of delvardine and its analogues into the p66 domain of HIV-1 reverse transcriptase: screening using molecular mechanics-generalized born/surface area and absorption, distribution, metabolism and excretion properties

    Indian Academy of Sciences (India)

    Dipankar Sengupta; Deeptak Verma; Pradeep K Naik

    2007-12-01

    Delvardine and its structural derivatives are important non-nucleoside HIV-1 reverse transcriptase inhibitors (NNRTIs). In this work, 15 delvardine analogues were studied. A free energy-of-binding (FEB) expression was developed in the form of an optimized linear combination of van der Waal (vdW), electrostatic, solvation and solvent-accessible surface area (SASA) energy terms. The solvation energy terms estimated by generalized born/surface area (GB/SA) play an important role in predicting the binding affinity of delvardine analogues. Out of 15 derivatives, substitution of CH3 with H at the Y and R positions, as well as substitution of SO2CH3 with only CH2 at the Z position in S2, S8 and S12 analogues, were found to be the most potent (glide score = –7.60, –8.06 and –7.44; pIC50 = 7.28, 7.37 and 7.64) in comparison with the template delvardine (which is used currently as the drug candidate). All the three analogues also passed the absorption, distribution, metabolism and excretion (ADME) screening and Lipinski’s rule of 5, and have the potential to be used for second-generation drug development. The work demonstrates that dock molecular mechanics-generalized born/surface area (MM–GB/SA–ADME) is a promising approach to predict the binding activity of ligands to the receptor and further screen for a successful candidate drug in a computer-aided rational drug design.

  16. Mapping between the order of thermal denaturation and the shape of the critical line of mechanical unzipping in 1-dimensional DNA models

    CERN Document Server

    Buyukdagli, Sahin; 10.1016/j.cplett.2009.11.061

    2010-01-01

    In this Letter, we investigate the link between thermal denaturation and mechanical unzipping for two models of DNA, namely the Dauxois-Peyrard-Bishop model and a variant thereof we proposed recently. We show that the critical line that separates zipped from unzipped DNA sequences in mechanical unzipping experiments is a power-law in the temperature-force plane. We also prove that for the investigated models the corresponding critical exponent is proportional to the critical exponent alpha, which characterizes the behaviour of the specific heat in the neighbourhood of the critical temperature for thermal denaturation.

  17. Order in Chaos

    DEFF Research Database (Denmark)

    Hansen, Bertel Teilfeldt; Olsen, Asmus Leth

    2014-01-01

    Ballot order effects are well documented in established democracies, but less so in fragile post-conflict settings. We test for the presence of ballot order effects in the 2010 parliamentary election in Afghanistan. Turning out for the 2010 election was a potentially life-threatening endeavor...... for the Afghan voter. The election provides a first look at ballot order effects in a high stakes, post-conflict setting. In this setting limited cognitive skills and information are more likely explanations of potential ballot order effects than mechanisms of lacking of effort or ambivalence of choice...

  18. Extending the strong-field approximation of high-order harmonic generation to polar molecules: gating mechanisms and extension of the harmonic cutoff

    DEFF Research Database (Denmark)

    Etches, Adam; Madsen, Lars Bojer

    2010-01-01

    Polar molecules such as CO are interesting target systems for high-order harmonic generation (HHG) as they can be oriented with current laser techniques, thus allowing the study of systems without inversion symmetry. However, the asymmetry of the molecule also means that the molecular orbitals...

  19. Time reversibility, computer simulation, algorithms, chaos

    CERN Document Server

    Hoover, William Graham

    2012-01-01

    A small army of physicists, chemists, mathematicians, and engineers has joined forces to attack a classic problem, the "reversibility paradox", with modern tools. This book describes their work from the perspective of computer simulation, emphasizing the author's approach to the problem of understanding the compatibility, and even inevitability, of the irreversible second law of thermodynamics with an underlying time-reversible mechanics. Computer simulation has made it possible to probe reversibility from a variety of directions and "chaos theory" or "nonlinear dynamics" has supplied a useful vocabulary and a set of concepts, which allow a fuller explanation of irreversibility than that available to Boltzmann or to Green, Kubo and Onsager. Clear illustration of concepts is emphasized throughout, and reinforced with a glossary of technical terms from the specialized fields which have been combined here to focus on a common theme. The book begins with a discussion, contrasting the idealized reversibility of ba...

  20. Dynamic effects in reversible hydro systems towards safety solutions

    Energy Technology Data Exchange (ETDEWEB)

    Morgado, Pedro A.; Ramos, Helena M. [Civil Engineering Department and CEHIDRO, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001, Lisbon (Portugal)

    2010-07-01

    The purpose of this paper is to establish general strategies to evaluate the dynamic effects occurring in reversible hydro systems (i.e. turbine/pumping) with long penstocks resulting from the regular operation of the hydro equipments and, most significantly, from accidental events. It is of great importance these particular aspects are considered in the early stages of a design, in order to ensure the best technical, economical and safety operation for each developed solution. This work presents two complementary approaches to the study of dynamic effects associated to reversible hydro systems based on a parametric analysis and a simulation-based procedure, as well as in the definition of design and operation rules to guarantee a safe solution. The first approach establishes the dynamic behavior of the system by means of a parametric analysis of the hydraulic and the hydro mechanical aspects associated to system operation. Based on this methodology, it is possible to estimate the maximum upsurge, the flow variation under turbogenerators runaway conditions and a valve manoeuvre. The second approach consists in the implementation of a numerical model that simulates accurately enough, the interaction between different components of the system during transient flow regimes associated to the hydropower load rejection, pumps shutdown, actuation of upsurge protection devices and wave propagations along the all system. This methodology gathers the necessary tools for the computational transient analysis of a complex reversible system.

  1. Reversible Communicating Processes

    Directory of Open Access Journals (Sweden)

    Geoffrey Brown

    2016-02-01

    Full Text Available Reversible distributed programs have the ability to abort unproductive computation paths and backtrack, while unwinding communication that occurred in the aborted paths. While it is natural to assume that reversibility implies full state recovery (as with traditional roll-back recovery protocols, an interesting alternative is to separate backtracking from local state recovery. For example, such a model could be used to create complex transactions out of nested compensable transactions where a programmer-supplied compensation defines the work required to "unwind" a transaction. Reversible distributed computing has received considerable theoretical attention, but little reduction to practice; the few published implementations of languages supporting reversibility depend upon a high degree of central control. The objective of this paper is to demonstrate that a practical reversible distributed language can be efficiently implemented in a fully distributed manner. We discuss such a language, supporting CSP-style synchronous communication, embedded in Scala. While this language provided the motivation for the work described in this paper, our focus is upon the distributed implementation. In particular, we demonstrate that a "high-level" semantic model can be implemented using a simple point-to-point protocol.

  2. Reverse Design and Kinematic Analysis of Non-circular Planetary Gear Trains Weft Insertion Mechanism%非圆齿轮行星轮系引纬机构的反求设计与运动学分析

    Institute of Scientific and Technical Information of China (English)

    陈建能; 王英; 任根勇; 赵雄; 雷昌毅

    2012-01-01

    In order to analyze the kinematic characteristics of non-circular planetary gear trains weft insertion mechanism and then obtain a group of preferable parameters, a kinematic model of this mechanism was established. Besides, the aided analytical and kinematic simulation software was compiled based on Visual Basic 6. 0. The influences of several important parameters on the shape of pitch curves of the non-circular gears in this mechanism were analyzed, and a group of preferable structural parameters were obtained. The movement simulation analysis was conducted under this group of parameters. Under the condition of same reed width and rotary speed of loom spindle, this novel mechanism was compared with the weft insertion mechanism applied on the TT96 rapier loom. The conclusion shows that non-circular planetary gear trains weft insertion mechanism has smaller maximum value of velocity and acceleration, and it can meet the requirments of weft insertion.%为了分析非圆齿轮行星轮系引纬机构的运动学特性并获得一组较优的参数,建立了该机构的运动学分析模型,基于Visual Basic 6.0平台编写了该机构的辅助分析与运动仿真软件,分析了几个重要参数对机构中非圆齿轮节曲线的影响,得到了一组较优的机构参数.对该组参数下的引纬机构进行运动仿真分析,在相同筘幅和织机主轴转速条件下,对非圆齿轮行星轮系引纬机构和TT96剑杆织机引纬机构的运动学特性进行了比较,结果表明非圆齿轮行星轮系引纬机构具有较小的最大速度值和最大加速度值,能够满足引纬要求.

  3. Structure and mechanism in a second-order statistical state dynamics model of self-sustaining turbulence in plane Couette flow

    CERN Document Server

    Farrell, Brian F

    2016-01-01

    This paper describes a study of the self-sustaining process (SSP) that maintains turbulence in wall-bounded shear flow. The study uses Couette flow and is based on a statistical state dynamics (SSD) model closed at second order with state variables the streamwise mean (first cumulant) and the covariance of perturbations (second cumulant). The SSD is closed by either neglecting or stochastically parameterizing the perturbation--perturbation nonlinearity in the perturbation covariance equation. This class of quasi-linear SSD models, which are referred to as RNL models, are a second order SSD systems that includes the stochastic structural stability theory (S3T or equivalently RNL$_\\infty$) model which is used in this study. Comparisons of turbulence maintained in DNS and RNL simulations have demonstrated that RNL systems self-sustain turbulence with a mean flow and perturbation structure consistent with DNS. The current results isolate the dynamical components sustaining turbulence in the S3T system concentrati...

  4. Ordered fibrillar morphology of donor-acceptor conjugated copolymers at multiple scales via blending with flexible polymers and solvent vapor annealing: insight into photophysics and mechanism.

    Science.gov (United States)

    Wang, Haiyang; Liu, Jiangang; Xu, Yaozhuo; Yu, Xinhong; Xing, Rubo; Han, Yanchun

    2014-01-28

    The ordered, aligned fibrillar morphology at multiple scales of a donor-acceptor (D-A) conjugated copolymer of 3,6-bis-(thiophen-2-yl)-N,N'-bis(2-octyl-1-dodecyl)-1,4-dioxo-pyrrolo[3,4-c]pyrrole and thieno[3,2-b]thiophene (PDBT-TT) was prepared via blending with flexible polymers (PS13.7k, PDBT-TT/PS = 1/10 w/w) followed by chloroform (CF) solvent vapor annealing (SVA) for 24 h. The aligned fibrillar bundles were of about 500 nm width, consisting of parallel aligned nanofibrils of ab. 10 nm width. It was found that the direction of backbones in nanofibrils was parallel to the long axis of nanofibrils, which implied an intense intra-chain conjugation associated with extended backbones and J-aggregation of PDBT-TT. This ordered morphology corresponded to the characteristic photophysical features of (i) red-shifted absorption arising from J-aggregation, (ii) larger Davydov splitting, (iii) the prevailing absorbance of J-aggregation over H-aggregation in its UV-Vis spectrum and (iv) more red-shifted max photoluminescence emission, compared with the films prepared via the other methods. By investigating the Raman spectra and XRD profiles, it is proposed that the origin of the best morphological and photophysical order is the combination of blending and SVA. The limited and "flexible" space formed due to phase separation between PDBT-TT and PS facilitated the motion of rigid PDBT-TT chains and promoted their stacking order as templates, and CF vapor assisted the conformational transition of chains to more "coil-like" to help them reorganize in a thermodynamic stable way.

  5. Influence of high-order mechanics on simulation of glacier response to climate change: insights from Haig Glacier, Canadian Rocky Mountains

    OpenAIRE

    S. Adhikari; Marshall, S. J.

    2013-01-01

    Evolution of glaciers in response to climate change has mostly been simulated using simplified dynamical models. Because these models do not account for the influence of high-order physics, corresponding results may exhibit some biases. For Haig Glacier in the Canadian Rocky Mountains, we test this hypothesis by comparing simulation results obtained from 3-D numerical models that deal with different assumptions concerning physics, ranging ...

  6. Post-crystallization increases in the mechanical strength of self-assembled fibrillar networks is due to an increase in network supramolecular ordering

    Science.gov (United States)

    Rogers, Michael A.; Wright, Amanda J.; Marangoni, Alejandro G.

    2008-11-01

    Fibre-fibre interactions strongly influence the elastic properties of an organogel and are of critical importance to the ability of the network to entrain liquid oil. At 30 °C, there was a significant decrease in the storage modulus in time due to a decrease in the amount of crystalline material (i.e. a decrease in the free induction decay (FID) amplitude) and order of crystalline material (i.e. an increase in the FID T2 relaxation time (i.e. a measure of proton mobility)). Conversely, at 5 °C, there was an increase in G' in time but no changes were observed in both the amount of crystalline material and its order. This increase in G' was accompanied by a significant increase in the enthalpy of melt and the melting temperature, which translated to a significant increase in the entropy of melt of the system. This decrease in the absolute entropy of the system in time probably arose due to an increase in the number of van der Waals interactions between 12-hydroxystearic acid fibres. Hence the increased order of the system is due to the fibre-fibre interactions which results in a significant increase in G' in time at 5 °C.

  7. Post-crystallization increases in the mechanical strength of self-assembled fibrillar networks is due to an increase in network supramolecular ordering

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Michael A; Marangoni, Alejandro G [Department of Food Science, University of Guelph, Guelph, ON, N1G2W1 (Canada); Wright, Amanda J [Department of Human Health and Nutritional Science, University of Guelph, Guelph, ON, N1G2W1 (Canada)], E-mail: amarango@uoguelph.ca

    2008-11-07

    Fibre-fibre interactions strongly influence the elastic properties of an organogel and are of critical importance to the ability of the network to entrain liquid oil. At 30 deg. C, there was a significant decrease in the storage modulus in time due to a decrease in the amount of crystalline material (i.e. a decrease in the free induction decay (FID) amplitude) and order of crystalline material (i.e. an increase in the FID T{sub 2} relaxation time (i.e. a measure of proton mobility)). Conversely, at 5 deg. C, there was an increase in G' in time but no changes were observed in both the amount of crystalline material and its order. This increase in G' was accompanied by a significant increase in the enthalpy of melt and the melting temperature, which translated to a significant increase in the entropy of melt of the system. This decrease in the absolute entropy of the system in time probably arose due to an increase in the number of van der Waals interactions between 12-hydroxystearic acid fibres. Hence the increased order of the system is due to the fibre-fibre interactions which results in a significant increase in G' in time at 5 deg. C.

  8. 胆碱能受体激动剂逆转天疱疮棘层松解的机制研究%Mechanisms underlying the reversal of acantholysis in pemphigus by a cholinergic receptor agonist

    Institute of Scientific and Technical Information of China (English)

    李志量; 张洁尘; 徐浩翔; 杨永红; 冯素英; 王宝玺

    2015-01-01

    目的 研究胆碱能受体激动剂对天疱疮棘层松解的逆转作用及其机制.方法 将HaCaT细胞与寻常型天疱疮IgG(PV-IgG)共培养建成天疱疮细胞模型后,再加入胆碱能受体激动剂卡巴胆碱共培养,以PV-IgG诱导的天疱疮细胞模型作为对照,通过细胞解离实验定量分析卡巴胆碱对棘层松解的逆转情况,用免疫荧光方法定性观察桥粒蛋白变化;分别用RIPA和Triton X-100裂解细胞,得到总蛋白和胞质蛋白,用蛋白免疫印迹灰度值定性分析HaCaT细胞表面与黏附相关的桥粒芯蛋白3(Dsg3)、桥斑珠蛋白(PG)的变化,不同时间点p38丝裂原活化蛋白激酶(p38 MAPK)、表皮生长因子受体(EGFR)的磷酸化水平;用定量聚合酶链反应(qPCR)检测上述细胞表面蛋白在mRNA水平的变化;通过免疫共沉淀方法定性分析Dsg3与PG相互作用的变化情况.结果 PV-IgG组细胞碎片数为46.67±2.03,卡巴胆碱组为18.67±2.52,两组比较,t=11.22,P< 0.01;免疫荧光实验发现,卡巴胆碱可以逆转PV-IgG所致的桥粒分子内化.在天疱疮细胞模型中,细胞总的Dsg3和PG含量下降,非桥粒部分的Dsg3下降,非桥粒PG含量增加,且Dsg3与PG的相互作用减弱,加入卡巴胆碱后可逆转上述变化.卡巴胆碱也可使Dsg3 mRNA的相对表达量(2-△△Ct)由1.428±0.215增加至4.974±0.948(t=3.65,P=0.01),PG mRNA的相对表达量由1.563±0.247增加至13.420±1.715(t=6.85,P<0.01).磷酸化实验中,卡巴胆碱可以抑制EGFR磷酸化,而对p38 MAPK磷酸化无明显影响.结论 胆碱能受体激动剂卡巴胆碱具有逆转棘层松解的作用,这种逆转作用的机制可能包括:抑制Dsg3和PG内化并增加其表达,增强Dsg3与PG的相互作用,抑制棘层松解关键信号EGFR的磷酸化.%Objective To evaluate the reversal effect of a cholinergic receptor agonist on acantholysis in pemphigus,and to investigate its mechanism.Methods Human HaCaT keratinocytes were co-cultured with

  9. 机械蒸汽再压缩技术处理反渗透浓水的中试研究%Pilot Study on Mechanical Vapor Recompression Technology for Treatment of Concentrated Water from Reverse Osmosis Process

    Institute of Scientific and Technical Information of China (English)

    张金鸿; 侯霙; 李海芳; 唐运平

    2011-01-01

    近年来,反渗透(RO)在污水厂二级出水深度处理中的应用越来越多.然而,RO浓水的含盐量较高、有机物难于降解,采用常规方法处理时出水水质难于达到排放标准.采用机械蒸汽再压缩技术(MVR)对某污水厂的反渗透浓水进行了6倍浓缩的中试,其出水COD≤50 mg/L、NH-N≤10 mg/L,可以达到(GB/T 18920-2002)的要求;COD、TDS、Mg和色度等指标的浓缩倍数与体系的浓缩倍数基本一致,而浓缩水中的TP、SiO、TN、NH-N浓度却低于原水的,这主要是由于磷酸盐、硅酸盐的沉淀和氨气逸出所致.另外,钙盐等的沉淀作用还造成浓缩水中SS浓度的增加.由此可见,利用MVR处理反渗透浓水在技术上是可行的,但是需要增加沉淀物的预处理和排出气体的收集处理装置.%Recently, the application of reverse osmosis (RO) in advanced treatment of effluent form WWTP becomes very popular. However, due to high salinity and refractory organic compounds in concentrated water of RO, the effluent treated by traditional processes can not meet the discharge standard. A pilot experiment at a concentration factor of 6 was conducted to treat concentrated water from reverse osmosis (RO) process in a sewage treatment plant using mechanical vapor recompression (MVR)technology. COD and NH3 -N in the effluent from MVR process are equal to or less than 50 mg/L and 10 mg/L, meeting the Reuse of Urban Recycling Water-Water Quality Standard for Urban Miscellaneous Water Consumption (GB/T 18920 -2002). The concentration factors of COD, TDS, Mg2+ and color in concentrated water of MVR are similar to those in concentrated water of RO. However, the concentration factors of TP, SiO2, TN and NH3 - N are lower than those in concentrated water of RO due to escape of ammonia and precipitation of phosphate and silicate. In addition, precipitation of calcium salt causes increase of SS in concentrated water of MVR. The experiment shows that MVR technology is

  10. Radiation controlling reversible window

    Energy Technology Data Exchange (ETDEWEB)

    Gell, H.A. Jr.

    1980-01-01

    A coated glass glazing system is presented including a transparent glass substrate having one surface coated with a radiation absorptive film which is overcoated with a radiation reflective film by a technique which renders the radiation reflective film radiation absorptive at the surface contracting the radiating absorptive film. The coated glass system is used as glazing for storm windows which are adapted to be reversible so that the radiation reflective surface may be exposed to the outside of the dwelling during the warm seasons to prevent excessive solar radiation from entering a dwelling and reversed during cold seasons to absorb solar radiation and utilize it to aid in keeping the dwelling interior warm.

  11. Focusing over Optical Fiber Using Time Reversal

    DEFF Research Database (Denmark)

    Piels, Molly; Porto da Silva, Edson; Estaran Tolosa, Jose Manuel

    2015-01-01

    A time-reversal array in multimode fiber is proposed for lossless remotely controlled switching using passive optical splitters. The signal to be transmitted is digitally pre-distorted so that it is routed through the physical layer in order to arrive at only one receiver in an array. System...

  12. Spectroscopy of mechanical dissipation in micro-mechanical membranes

    CERN Document Server

    Jöckel, Andreas; Korppi, Maria; Camerer, Stephan; Hunger, David; Mader, Matthias; Treutlein, Philipp

    2011-01-01

    We measure the frequency dependence of the mechanical quality factor (Q) of SiN membrane oscillators and observe a resonant variation of Q by more than two orders of magnitude. The frequency of the fundamental mechanical mode is tuned reversibly by up to 40% through local heating with a laser. Several distinct resonances in Q are observed that can be explained by coupling to membrane frame modes. Away from the resonances, the background Q is independent of frequency and temperature in the measured range.

  13. Discovery of Reversible Crystallization of Macromolecules

    Science.gov (United States)

    Wunderlich, Bernhard

    2004-03-01

    For 10 years "reversing melting" was observed with temperature-modulated differential scanning calorimetry, TMDSC. This reversing melting is the first harmonic response beyond that caused by the heat capacity of a metastable, semicrystalline macromolecular sample. Before one can identify "reversible melting," the calorimeter response must be corrected for loss of linearity, stationarity, frequency, amplitude, and instrument lag, or proper experiment-design must avoid these problems. Using quasi-isothermal TMDSC, the following observations were made [Prog. Polymer Sci. 28 (2003) 383-450]: Equilibrium crystals of polymers may melt at the equilibrium melting-temperature, but crystallization needs supercooling, even in the presence of crystal nuclei, making the overall process irreversible. Metastable, folded-chain crystals of the same molecules also melt irreversibly, however, may have some specific reversibility. Flexible, linear molecules of up to 10 nm length may melt fully reversibly. Macromolecules of less flexibility may lose the ability to melt reversibly. Decoupling of molecular segments, molecular nucleation, segregation of molar masses, rigid amorphous fractions, effects of equilibrium point defects in crystals and glasses, and transition-less ordering and solidification will be discussed in some detail. Supported by NSF, Polymers Program, DMR-0312233, and the Div. of Mat. Sci., BES, of DOE at ORNL, managed by UT-Battelle, LLC, for the U.S. Department of Energy, DOE-AC05-00OR22725.

  14. Time reversal communication system

    Science.gov (United States)

    Candy, James V.; Meyer, Alan W.

    2008-12-02

    A system of transmitting a signal through a channel medium comprises digitizing the signal, time-reversing the digitized signal, and transmitting the signal through the channel medium. The channel medium may be air, earth, water, tissue, metal, and/or non-metal.

  15. Engineering Encounters: Reverse Engineering

    Science.gov (United States)

    McGowan, Veronica Cassone; Ventura, Marcia; Bell, Philip

    2017-01-01

    This column presents ideas and techniques to enhance your science teaching. This month's issue shares information on how students' everyday experiences can support science learning through engineering design. In this article, the authors outline a reverse-engineering model of instruction and describe one example of how it looked in our fifth-grade…

  16. Reverse Coherent Information

    Science.gov (United States)

    García-Patrón, Raúl; Pirandola, Stefano; Lloyd, Seth; Shapiro, Jeffrey H.

    2009-05-01

    In this Letter we define a family of entanglement distribution protocols assisted by feedback classical communication that gives an operational interpretation to reverse coherent information, i.e., the symmetric counterpart of the well-known coherent information. This leads to the definition of a new entanglement distribution capacity that exceeds the unassisted capacity for some interesting channels.

  17. Reversed extension flow

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik K.

    2008-01-01

    Afilament stretching rheometer (FSR) was used for measuring the start-up of uni-axial elongational flow followed by reversed bi-axial flow, both with a constant elongational rate. A narrow molecular mass distribution linear polystyrene with a molecular weight of 145 kg / mole wis subjected to the...

  18. On reverse hypercontractivity

    CERN Document Server

    Mossel, Elchanan; Sen, Arnab

    2011-01-01

    We study the notion of reverse hypercontractivity. We show that reverse hypercontractive inequalities are implied by standard hypercontractive inequalities as well as by the modified log-Sobolev inequality. Our proof is based on a new comparison lemma for Dirichlet forms and an extension of the Strook-Varapolos inequality. A consequence of our analysis is that {\\em all} simple operators $L=Id-\\E$ as well as their tensors satisfy uniform reverse hypercontractive inequalities. That is, for all $qreverse hypercontractive inequalities established here imply new mixing and isoperimetric results for short random walks in product spaces, for certain card-shufflings, for Glauber dynamics in high-temperat...

  19. Reversing Discrimination: A Perspective

    Science.gov (United States)

    Pati, Gopal; Reilly, Charles W.

    1977-01-01

    Examines the debate over affirmative action and reverse discrimination, and discusses how and why the present dilemma has developed. Suggests that organizations can best address the problem through an honest, in-depth analysis of their organizational structure and management practices. (JG)

  20. Study of Time Reversal in Complex Systems

    Science.gov (United States)

    2014-01-02

    In this paper we present conclusions of a study of irreversibility in physical processes, using the conceptual formalism of the epsilon -machine. The...irreversibility, and is examined in more detail in the framework of topological epsilon -machines. Detailed study of the mechanisms involved in time-reversal of