Jain, Shekhar; Dominik, Aleksandra; Chapman, Walter G
2007-12-28
A density functional theory based on Wertheim's first order perturbation theory is developed for inhomogeneous complex fluids. The theory is derived along similar lines as interfacial statistical associating fluid theory [S. Tripathi and W. G. Chapman, J. Chem. Phys. 122, 094506 (2005)]. However, the derivation is more general and applies broadly to a range of systems, retaining the simplicity of a segment density based theory. Furthermore, the theory gives the exact density profile for ideal chains in an external field. The general avail of the theory has been demonstrated by applying the theory to lipids near surfaces, lipid bilayers, and copolymer thin films. The theoretical results show excellent agreement with the results from molecular simulations.
Density functional theory for inhomogeneous associating chain fluids.
Bryk, P; Sokołowski, S; Pizio, O
2006-07-14
We propose a nonlocal density functional theory for associating chain molecules. The chains are modeled as tangent spheres, which interact via Lennard-Jones (12,6) attractive interactions. A selected segment contains additional, short-ranged, highly directional interaction sites. The theory incorporates an accurate treatment of the chain molecules via the intramolecular potential formalism and should accurately describe systems with strongly varying external fields, e.g., attractive walls. Within our approach we investigate the structure of the liquid-vapor interface and capillary condensation of a simple model of associating chains with only one associating site placed on the first segment. In general, the properties of inhomogeneous associating chains depend on the association energy. Similar to the bulk systems we find the behavior of associating chains of a given length to be in between that for the nonassociating chains of the same length and that for the nonassociating chains twice as large.
ADSORPTION OF ASSOCIATING FLUIDS AT ACTIVE SURFACES: A DENSITY FUNCTIONAL THEORY
Directory of Open Access Journals (Sweden)
S.Tripathi
2003-01-01
Full Text Available We present a density functional theory (DFT to describe adsorption in systems where molecules of associating fluids can bond (or associate with discrete, localized functional groups attached to the surfaces, in addition to other fluid molecules. For such systems as water adsorbing on activated carbon, silica, clay minerals etc. this is a realistic model to account for surface heterogeneity rather than using a continuous smeared surface-fluid potential employed in most of the theoretical works on adsorption on heterogeneous surfaces. Association is modelled within the framework of first order thermodynamic perturbation theory (TPT1. The new theory accurately predicts the distribution of bonded and non-bonded species and adsorption behavior under various conditions of bulk pressure, surface-fluid and fluid-fluid association strengths. Competition between the surface-fluid and fluid-fluid association is analyzed for fluids with multiple association sites and its impact on adsorption is discussed. The theory, supported by simulations demonstrates that the extent and the nature of adsorption (e.g. monolayer vary with the number of association sites on the fluid molecules.
Marshall, Bennett D; Chapman, Walter G
2013-08-07
We develop a new theory for associating fluids with multiple association sites. The theory accounts for small bond angle effects such as steric hindrance, ring formation, and double bonding. The theory is validated against Monte Carlo simulations for the case of a fluid of patchy colloid particles with three patches and is found to be very accurate. Once validated, the theory is applied to study the phase diagram of a fluid composed of three patch colloids. It is found that bond angle has a significant effect on the phase diagram and the very existence of a liquid-vapor transition.
DEFF Research Database (Denmark)
Karakatsani, Eirini; Kontogeorgis, Georgios; Economou, Ioannis
2006-01-01
Perturbed chain-statistical associating fluid theory (PC-SAFT) was extended rigorously to polar fluids based on the theory of Stell and co-workers [Mol. Phys. 1977, 33, 987]. The new PC-PSAFT was simplified to truncated PC-PSAFT (tPC-PSAFT) so that it can be practical for real polar fluid thermod...... pressures are calculated. Comparisons against PC-SAFT calculations are made. It is shown that tPC-PSAFT is an accurate model for polar fluid mixture phase equilibria....
Haghmoradi, Amin; Wang, Le; Chapman, Walter G.
2017-02-01
In this manuscript we extend Wertheim’s two-density formalism beyond its first order to model a system of fluid molecules with a single association site close to a planar hard wall with association sites on its surface in a density functional theory framework. The association sites of the fluid molecules are small enough that they can form only one bond, while the wall association sites are large enough to bond with more than one fluid molecule. The effects of temperature and of bulk fluid and wall site densities on the fluid density profile, extent of association, and competition between single and double bonding of fluid segments at the wall sites versus distance from the wall are presented. The theory predictions are compared with new Monte Carlo simulation results and they are in good agreement. The theory captures the surface coverage over wide ranges of temperature and bulk density by introducing the effect of steric hindrance in fluid association at a wall site.
Predicting adsorption isotherms using a two-dimensional statistical associating fluid theory
Martinez, Alejandro; Castro, Martin; McCabe, Clare; Gil-Villegas, Alejandro
2007-02-01
A molecular thermodynamics approach is developed in order to describe the adsorption of fluids on solid surfaces. The new theory is based on the statistical associating fluid theory for potentials of variable range [A. Gil-Villegas et al., J. Chem. Phys. 106, 4168 (1997)] and uses a quasi-two-dimensional approximation to describe the properties of adsorbed fluids. The theory is tested against Gibbs ensemble Monte Carlo simulations and excellent agreement with the theoretical predictions is achieved. Additionally the authors use the new approach to describe the adsorption isotherms for nitrogen and methane on dry activated carbon.
Institute of Scientific and Technical Information of China (English)
许波; 李浩然; 王从敏; 许映杰; 韩世钧
2005-01-01
1H NMR chemical shifts of binary aqueous mixtures of acylamide, alcohol, dimethyl sulphoxide (DMSO), and acetone are correlated by statistical associating fluid theory (SAFT) association model. The comparison between SAFT association model and Wilson equation shows that the former is better for dealing with aqueous solutions. Finally, the specialties of both models are discussed.
Trejos, Víctor M.; Gil-Villegas, Alejandro
2012-05-01
Thermodynamic properties of quantum fluids are described using an extended version of the statistical associating fluid theory for potentials of variable range (SAFT-VR) that takes into account quantum corrections to the Helmholtz free energy A, based on the Wentzel-Kramers-Brillouin approximation. We present the theoretical background of this approach (SAFT-VRQ), considering two different cases depending on the continuous or discontinuous nature of the particles pair interaction. For the case of continuous potentials, we demonstrate that the standard Wigner-Kirkwood theory for quantum fluids can be derived from the de Broglie-Bohm formalism for quantum mechanics that can be incorporated within the Barker and Henderson perturbation theory for liquids in a straightforward way. When the particles interact via a discontinuous pair potential, the SAFT-VR method can be combined with the perturbation theory developed by Singh and Sinha [J. Chem. Phys. 67, 3645 (1977); Singh and Sinha J. Chem. Phys. 68, 562 (1978)]. We present an analytical expression for the first-order quantum perturbation term for a square-well potential, and the theory is applied to model thermodynamic properties of hydrogen, deuterium, neon, and helium-4. Vapor-liquid equilibrium, liquid and vapor densities, isochoric and isobaric heat capacities, Joule-Thomson coefficients and inversion curves are predicted accurately with respect to experimental data. We find that quantum corrections are important for the global behavior of properties of these fluids and not only for the low-temperature regime. Predictions obtained for hydrogen compare very favorably with respect to cubic equations of state.
Trejos, Víctor M; Gil-Villegas, Alejandro
2012-05-14
Thermodynamic properties of quantum fluids are described using an extended version of the statistical associating fluid theory for potentials of variable range (SAFT-VR) that takes into account quantum corrections to the Helmholtz free energy A, based on the Wentzel-Kramers-Brillouin approximation. We present the theoretical background of this approach (SAFT-VRQ), considering two different cases depending on the continuous or discontinuous nature of the particles pair interaction. For the case of continuous potentials, we demonstrate that the standard Wigner-Kirkwood theory for quantum fluids can be derived from the de Broglie-Bohm formalism for quantum mechanics that can be incorporated within the Barker and Henderson perturbation theory for liquids in a straightforward way. When the particles interact via a discontinuous pair potential, the SAFT-VR method can be combined with the perturbation theory developed by Singh and Sinha [J. Chem. Phys. 67, 3645 (1977); and ibid. 68, 562 (1978)]. We present an analytical expression for the first-order quantum perturbation term for a square-well potential, and the theory is applied to model thermodynamic properties of hydrogen, deuterium, neon, and helium-4. Vapor-liquid equilibrium, liquid and vapor densities, isochoric and isobaric heat capacities, Joule-Thomson coefficients and inversion curves are predicted accurately with respect to experimental data. We find that quantum corrections are important for the global behavior of properties of these fluids and not only for the low-temperature regime. Predictions obtained for hydrogen compare very favorably with respect to cubic equations of state.
Modeling of aqueous electrolyte solutions with perturbed-chain statistical associated fluid theory
DEFF Research Database (Denmark)
Cameretti, Luca F.; Sadowski, Gabriele; Mollerup, Jørgen
2005-01-01
The vapor pressures and liquid densities of single-salt electrolyte solutions containing NaCl, LiCl, KCl, NaBr, LiBr, KBr, NaI, LiI, KI, Li2SO4, Na2SO4, and K2SO4 were modeled with an equation of state based on perturbed-chain statistical associated fluid theory (PC-SAFT). The PC-SAFT model...
Cluster perturbation theory for the self-assembly of associating fluids into complex structures.
Marshall, Bennett D
2014-12-01
Wertheim's two-density thermodynamic perturbation theory (TPT) has proven to be an indispensable statistical mechanical tool in the description of associating fluids with a single association site. TPT was developed to enforce the monovalence of the hydrogen bond and only recently has been extended to account for divalent association sites. It has been shown through experiment and molecular simulation that certain one-site associating fluids can self-assemble into complex extended supramolecular structures as a result of multiple bonding of association sites. In this paper we reorganize TPT into a form that is more easily applied to complex associated structures. The derived theory is general to all possible self-assemble structures. We obtain the free energy and bonding fractions in a general way in terms of single-cluster partition functions and averages. The new formalism removes any reference to graph theory allowing for the conceptually straightforward application of the two-density formalism to complex self-assembled structures.
Investigation of Vapor-Liquid Nucleation for Associating Fluids by Density Gradient Theory
Institute of Scientific and Technical Information of China (English)
FU Dong; LIU Jianmin
2009-01-01
An equation of state (EOS) applicable to both the uniform and non-uniform associating fluids was established by using the density-gradient expansion, in which the influence parameter κis formulated as a function of tempera-ture. The molecular parameters were regressed by fitting to the experimental data of vapor pressures and liquid den-sities. Within the framework of density gradient theory (DGT), the nucleation rates for water, heavy water, metha-nol, ethanol, 1-propanoi, 1-butanol, 1-pentanol and 1-hexanol were calculated. The results were satisfactory com-pared with the experimental data. Our study shows that DGT preserves all the advantages of density functional the-ory (DFT) in capturing the structure and properties of nucleus but gives much more accurate nucleation rates by adjusting the influence parameter.
Jiang, Hao; Panagiotopoulos, Athanassios Z.; Economou, Ioannis G.
2016-03-01
Statistical associating fluid theory (SAFT) is used to model CO2 solubilities in single and mixed electrolyte solutions. The proposed SAFT model implements an improved mean spherical approximation in the primitive model to represent the electrostatic interactions between ions, using a parameter K to correct the excess energies ("KMSA" for short). With the KMSA formalism, the proposed model is able to describe accurately mean ionic activity coefficients and liquid densities of electrolyte solutions including Na+, K+, Ca2+, Mg2+, Cl-, Br- and SO42- from 298.15 K to 473.15 K using mostly temperature independent parameters, with sole exception being the volume of anions. CO2 is modeled as a non-associating molecule, and temperature-dependent CO2-H2O and CO2-ion cross interactions are used to obtain CO2 solubilities in H2O and in single ion electrolyte solutions. Without any additional fitting parameters, CO2 solubilities in mixed electrolyte solutions and synthetic brines are predicted, in good agreement with experimental measurements.
DEFF Research Database (Denmark)
Liang, Xiaodong; Kontogeorgis, Georgios
2015-01-01
The Perturbed Chain-Statistical Associating Fluid Theory Equation of State (PC-SAFT EOS) has been successfully applied to model phase behavior of various types of systems, while it is also well-known that the PC-SAFT EOS has difficulties in describing some second-order derivative properties. In t...
Energy Technology Data Exchange (ETDEWEB)
Ji Peijun [College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Feng Wei [College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029 (China)]. E-mail: fengwei@mail.buct.edu.cn; Tan Tianwei [College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029 (China)
2007-07-15
The density of aqueous solutions of amino acids has been modeled with the statistical associating fluid theory (SAFT) equation of state. The modeling is accomplished by extending the previously developed new method to determine the SAFT parameters for amino acids. The modeled systems include {alpha}-alanine/H{sub 2}O, {beta}-alanine/H{sub 2}O, proline/H{sub 2}O, L-asparagine/H{sub 2}O, L-glutamine/H{sub 2}O, L-histidine/H{sub 2}O, serine/H{sub 2}O, glycine/H{sub 2}O, alanine/H{sub 2}O/sucrose, DL-valine/H{sub 2}O/sucrose, arginine/H{sub 2}O/sucrose, serine/H{sub 2}O/ethylene glycol, and glycine/H{sub 2}O/ethylene glycol. The density of binary solutions of amino acids has been correlated or predicted with a high precision. And then the density of multicomponent aqueous solutions of amino acids has been modeled based on the modeling results of binary systems, and a high accuracy of density calculations has been obtained. Finally, the water activities of DL-valine/H{sub 2}O, glycine/H{sub 2}O, and proline/H{sub 2}O have been predicted without using binary interaction parameters, and good results have been obtained.
Papaioannou, Vasileios; Lafitte, Thomas; Avendaño, Carlos; Adjiman, Claire S; Jackson, George; Müller, Erich A; Galindo, Amparo
2014-02-07
A generalization of the recent version of the statistical associating fluid theory for variable range Mie potentials [Lafitte et al., J. Chem. Phys. 139, 154504 (2013)] is formulated within the framework of a group contribution approach (SAFT-γ Mie). Molecules are represented as comprising distinct functional (chemical) groups based on a fused heteronuclear molecular model, where the interactions between segments are described with the Mie (generalized Lennard-Jonesium) potential of variable attractive and repulsive range. A key feature of the new theory is the accurate description of the monomeric group-group interactions by application of a high-temperature perturbation expansion up to third order. The capabilities of the SAFT-γ Mie approach are exemplified by studying the thermodynamic properties of two chemical families, the n-alkanes and the n-alkyl esters, by developing parameters for the methyl, methylene, and carboxylate functional groups (CH3, CH2, and COO). The approach is shown to describe accurately the fluid-phase behavior of the compounds considered with absolute average deviations of 1.20% and 0.42% for the vapor pressure and saturated liquid density, respectively, which represents a clear improvement over other existing SAFT-based group contribution approaches. The use of Mie potentials to describe the group-group interaction is shown to allow accurate simultaneous descriptions of the fluid-phase behavior and second-order thermodynamic derivative properties of the pure fluids based on a single set of group parameters. Furthermore, the application of the perturbation expansion to third order for the description of the reference monomeric fluid improves the predictions of the theory for the fluid-phase behavior of pure components in the near-critical region. The predictive capabilities of the approach stem from its formulation within a group-contribution formalism: predictions of the fluid-phase behavior and thermodynamic derivative properties of
Krawczyk, Jaroslaw; Croce, Salvatore; Chakrabarti, Buddhapriya; Tasche, Jos
The surface segregation in polymer mixtures remains a challenging problem for both academic exploration as well as industrial applications. Despite its ubiquity and several theoretical attempts a good agreement between computed and experimentally observed profiles has not yet been achieved. A simple theoretical model proposed in this context by Schmidt and Binder combines Flory-Huggins free energy of mixing with the square gradient theory of wetting of a wall by fluid. While the theory gives us a qualitative understanding of the surface induced segregation and the surface enrichment it lacks the quantitative comparison with the experiment. The statistical associating fluid theory (SAFT) allows us to calculate accurate free energy for a real polymeric materials. In an earlier work we had shown that increasing the bulk modulus of a polymer matrix through which small molecules migrate to the free surface causes reduction in the surface migrant fraction using Schmidt-Binder and self-consistent field theories. In this work we validate this idea by combining mean field theories and SAFT to identify parameter ranges where such an effect should be observable. Department of Molecular Physics, Łódź University of Technology, Żeromskiego 116, 90-924 Łódź, Poland.
Quantum field theory of fluids.
Gripaios, Ben; Sutherland, Dave
2015-02-20
The quantum theory of fields is largely based on studying perturbations around noninteracting, or free, field theories, which correspond to a collection of quantum-mechanical harmonic oscillators. The quantum theory of an ordinary fluid is "freer", in the sense that the noninteracting theory also contains an infinite collection of quantum-mechanical free particles, corresponding to vortex modes. By computing a variety of correlation functions at tree and loop level, we give evidence that a quantum perfect fluid can be consistently formulated as a low-energy, effective field theory. We speculate that the quantum behavior is radically different from both classical fluids and quantum fields.
Gripaios, Ben
2014-01-01
The quantum theory of fields is largely based on studying perturbations around non-interacting, or free, field theories, which correspond to a collection of quantum-mechanical harmonic oscillators. The quantum theory of an ordinary fluid is `freer', in the sense that the non-interacting theory also contains an infinite collection of quantum-mechanical free particles, corresponding to vortex modes. By computing a variety of correlation functions at tree- and loop-level, we give evidence that a quantum perfect fluid can be consistently formulated as a low-energy, effective field theory. We speculate that the quantum behaviour is radically different to both classical fluids and quantum fields, with interesting physical consequences for fluids in the low temperature regime.
Titan's atmosphere and surface liquid: New calculation using Statistical Associating Fluid Theory
Tan, Sugata P.; Kargel, Jeffrey S.; Marion, Giles M.
2013-01-01
The application of PC-SAFT equation of state (EOS) in analyzing the in situ measurement of atmospheric data by Huygens probe reveals new insights into Titan's atmosphere and surface liquids. The EOS offers the most reliable and accurate calculations in fluid phase equilibria at the cryogenic conditions encountered in Titan and other extra-terrestrial bodies. This paper and a succeeding one pertaining to solid phases are foundational introductions to a new thermodynamics tool (new to planetary science) and will open the way for many diverse planetological applications, but here we limit applications to Titan. Titan's lower stratosphere and lower troposphere are modeled as a well-mixed chemical solution with fixed overall composition of nine components. Using this model in the lower stratosphere, the dew point, below which condensation occurs, is calculated to be at an altitude of 65.3 km (T = 91.3 K, P = 0.031 bar). The first drop of liquid at this point is almost pure propane, which would form a haze (not a dense cloud) due to the minor abundance of this species. Using this model in the lower troposphere, the atmospheric methane mole fractions measured by Huygens probe is well predicted up to an altitude of 29 km, thus validates the model and the EOS. The surface liquid, which is assumed to be in thermodynamic equilibrium with the ground-level atmosphere, is dominated by C2H6, CH4, C3H8, and N2 with mole percents of 53%, 32%, 7%, and 7%, respectively, at a density of 614 kg/m3 in the equator. The effects of the temperature on the surface liquid composition are also discussed. Despite the small surface temperature difference between equatorial and polar regions (3.7 K), the composition of liquid in polar regions is very different from that in the equator: 68% CH4, 22% N2, and 8% C2H6 with the amount of liquid nine times larger than that in the equator at a 10%-smaller density of 551 kg/m3. The system is accurately estimated using the binary of CH4 and N2 only at an
Effective field theory of dissipative fluids
Crossley, Michael; Liu, Hong
2015-01-01
We develop an effective field theory for dissipative fluids which governs the dynamics of gapless modes associated to conserved quantities. The system is put in a curved spacetime and coupled to external sources for charged currents. The invariance of the hydrodynamical action under gauge symmetries and diffeomorphisms suggests a natural set of dynamical variables which provide a mapping between an emergent "fluid spacetime" and the physical spacetime. An essential aspect of our formulation is to identify the appropriate symmetries in the fluid spacetime. Our theory applies to nonlinear disturbances around a general density matrix. For a thermal density matrix, we require an additional Z_2 symmetry, to which we refer as the local KMS condition. This leads to the standard constraints of hydrodynamics, as well as a nonlinear generalization of the Onsager relations. It also leads to an emergent supersymmetry in the classical statistical regime, with a higher derivative version required for the full quantum regim...
Giner, Beatriz; Bandrés, Isabel; Carmen López, M.; Lafuente, Carlos; Galindo, Amparo
2007-10-01
A study of the phase equilibrium (experimental and modeled) of mixtures formed by a cyclic ether and haloalkanes has been derived. Experimental data for the isothermal vapor liquid equilibrium of mixtures formed by tetrahydrofuran and tetrahydropyran and isomeric chlorobutanes at temperatures of 298.15, 313.15, and 328.15K are presented. Experimental results have been discussed in terms of both molecular characteristics of pure compounds and potential intermolecular interaction between them using thermodynamic information of the mixtures obtained earlier. The statistical associating fluid theory for potential of variable range (SAFT-VR) approach together with standard combining rules without adjustable parameters has been used to model the phase equilibrium. Good agreement between experiment and the prediction is found with such a model. Mean absolute deviations for pressures are of the order of 1kPa, while less than 0.013mole fraction for vapor phase compositions. In order to improve the results obtained, a new modeling has been carried out by introducing a unique transferable parameter kij, which modifies the strength of the dispersion interaction between unlike components in the mixtures, and is valid for all the studied mixtures being not temperature or pressure dependent. This parameter together with the SAFT-VR approach provides a description of the vapor-liquid equilibrium of the mixtures that is in excellent agreement with the experimental data for most cases. The absolute deviations are of the order of 0.005mole fraction for vapor phase compositions and less than 0.3kPa for pressure, excepting for mixtures containing 2-chloro-2-methylpropane which deviations for pressure are larger. Results obtained in this work in the modeling of the phase equilibrium with the SAFT-VR equation of state have been compared to the ones obtained in a previous study when the approach was used to model similar mixtures with clear differences in the thermodynamic behavior. We
Mathematical theory of compressible fluid flow
Von Mises, Richard
2012-01-01
Mathematical Theory of Compressible Fluid Flow covers the conceptual and mathematical aspects of theory of compressible fluid flow. This five-chapter book specifically tackles the role of thermodynamics in the mechanics of compressible fluids. This text begins with a discussion on the general theory of characteristics of compressible fluid with its application. This topic is followed by a presentation of equations delineating the role of thermodynamics in compressible fluid mechanics. The discussion then shifts to the theory of shocks as asymptotic phenomena, which is set within the context of
Fluid Dynamics Theory, Computation, and Numerical Simulation
Pozrikidis, Constantine
2009-01-01
Fluid Dynamics: Theory, Computation, and Numerical Simulation is the only available book that extends the classical field of fluid dynamics into the realm of scientific computing in a way that is both comprehensive and accessible to the beginner. The theory of fluid dynamics, and the implementation of solution procedures into numerical algorithms, are discussed hand-in-hand and with reference to computer programming. This book is an accessible introduction to theoretical and computational fluid dynamics (CFD), written from a modern perspective that unifies theory and numerical practice. There are several additions and subject expansions in the Second Edition of Fluid Dynamics, including new Matlab and FORTRAN codes. Two distinguishing features of the discourse are: solution procedures and algorithms are developed immediately after problem formulations are presented, and numerical methods are introduced on a need-to-know basis and in increasing order of difficulty. Matlab codes are presented and discussed for ...
Fluid dynamics theory, computation, and numerical simulation
Pozrikidis, C
2001-01-01
Fluid Dynamics Theory, Computation, and Numerical Simulation is the only available book that extends the classical field of fluid dynamics into the realm of scientific computing in a way that is both comprehensive and accessible to the beginner The theory of fluid dynamics, and the implementation of solution procedures into numerical algorithms, are discussed hand-in-hand and with reference to computer programming This book is an accessible introduction to theoretical and computational fluid dynamics (CFD), written from a modern perspective that unifies theory and numerical practice There are several additions and subject expansions in the Second Edition of Fluid Dynamics, including new Matlab and FORTRAN codes Two distinguishing features of the discourse are solution procedures and algorithms are developed immediately after problem formulations are presented, and numerical methods are introduced on a need-to-know basis and in increasing order of difficulty Matlab codes are presented and discussed for a broad...
Nhu, Nguyen Van; Singh, Mahendra; Leonhard, Kai
2008-05-08
We have computed molecular descriptors for sizes, shapes, charge distributions, and dispersion interactions for 67 compounds using quantum chemical ab initio and density functional theory methods. For the same compounds, we have fitted the three perturbed-chain polar statistical associating fluid theory (PCP-SAFT) equation of state (EOS) parameters to experimental data and have performed a statistical analysis for relations between the descriptors and the EOS parameters. On this basis, an analysis of the physical significance of the parameters, the limits of the present descriptors, and the PCP-SAFT EOS has been performed. The result is a method that can be used to estimate the vapor pressure curve including the normal boiling point, the liquid volume, the enthalpy of vaporization, the critical data, mixture properties, and so on. When only two of the three parameters are predicted and one is adjusted to experimental normal boiling point data, excellent predictions of all investigated pure compound and mixture properties are obtained. We are convinced that the methodology presented in this work will lead to new EOS applications as well as improved EOS models whose predictive performance is likely to surpass that of most present quantum chemically based, quantitative structure-property relationship, and group contribution methods for a broad range of chemical substances.
Statistical mechanical theory of fluid mixtures
Zhao, Yueqiang; Wu, Zhengming; Liu, Weiwei
2014-01-01
A general statistical mechanical theory of fluid mixtures (liquid mixtures and gas mixtures) is developed based on the statistical mechanical expression of chemical potential of components in the grand canonical ensemble, which gives some new relationships between thermodynamic quantities (equilibrium ratio Ki, separation factor α and activity coefficient γi) and ensemble average potential energy u for one molecule. The statistical mechanical expressions of separation factor α and activity coefficient γi derived in this work make the fluid phase equilibrium calculations can be performed by molecular simulation simply and efficiently, or by the statistical thermodynamic approach (based on the saturated-vapor pressure of pure substance) that does not need microscopic intermolecular pair potential functions. The physical meaning of activity coefficient γi in the liquid phase is discussed in detail from a viewpoint of molecular thermodynamics. The calculated Vapor-Liquid Equilibrium (VLE) properties of argon-methane, methanol-water and n-hexane-benzene systems by this model fit well with experimental data in references, which indicates that this model is accurate and reliable in the prediction of VLE properties for small, large and strongly associating molecules; furthermore the statistical mechanical expressions of separation factor α and activity coefficient γi have good compatibility with classical thermodynamic equations and quantum mechanical COSMO-SAC approach.
Mathematical theory of compressible fluid flow
von Mises, Richard
2004-01-01
A pioneer in the fields of statistics and probability theory, Richard von Mises (1883-1953) made notable advances in boundary-layer-flow theory and airfoil design. This text on compressible flow, unfinished upon his sudden death, was subsequently completed in accordance with his plans, and von Mises' first three chapters were augmented with a survey of the theory of steady plane flow. Suitable as a text for advanced undergraduate and graduate students - as well as a reference for professionals - Mathematical Theory of Compressible Fluid Flow examines the fundamentals of high-speed flows, with
Fluid dynamics theory, computation, and numerical simulation
Pozrikidis, C
2017-01-01
This book provides an accessible introduction to the basic theory of fluid mechanics and computational fluid dynamics (CFD) from a modern perspective that unifies theory and numerical computation. Methods of scientific computing are introduced alongside with theoretical analysis and MATLAB® codes are presented and discussed for a broad range of topics: from interfacial shapes in hydrostatics, to vortex dynamics, to viscous flow, to turbulent flow, to panel methods for flow past airfoils. The third edition includes new topics, additional examples, solved and unsolved problems, and revised images. It adds more computational algorithms and MATLAB programs. It also incorporates discussion of the latest version of the fluid dynamics software library FDLIB, which is freely available online. FDLIB offers an extensive range of computer codes that demonstrate the implementation of elementary and advanced algorithms and provide an invaluable resource for research, teaching, classroom instruction, and self-study. This ...
Directory of Open Access Journals (Sweden)
Yu.V. Kalyuzhnyi
2012-06-01
Full Text Available The liquid-gas phase diagram for polydisperse dipolar hard-sphere fluid with polydispersity in the hard-sphere size and dipolar moment is calculated using extension of the recently proposed thermodynamic perturbation theory for central force (TPT-CF associating potential. To establish the connection with the phase behavior of ferrocolloidal dispersions it is assumed that the dipole moment is proportional to the cube of the hard-sphere diameter. We present and discuss the full phase diagram, which includes cloud and shadow curves, binodals and distribution functions of the coexisting daughter phases at different degrees of the system polydispersity. In all cases studied polydispersity increases the region of the phase instability and shifts the critical point to the higher values of the temperature and density. The larger size particles always fractionate to the liquid phase and the smaller size particles tend to move to the gas phase. At relatively high values of the system polydispersity three-phase coexistence is observed.
Schreckenberg, Jens M. A.; Dufal, Simon; Haslam, Andrew J.; Adjiman, Claire S.; Jackson, George; Galindo, Amparo
2014-09-01
An improved formulation of the extension of the statistical associating fluid theory for potentials of variable range to electrolytes (SAFT-VRE) is presented, incorporating a representation for the dielectric constant of the solution that takes into account the temperature, density and composition of the solvent. The proposed approach provides an excellent correlation of the dielectric-constant data available for a number of solvents including water, representative alcohols and carbon dioxide, and it is shown that the methodology can be used to treat mixed-solvent electrolyte solutions. Models for strong electrolytes of the metal-halide family are considered here. The salts are treated as fully dissociated and ion-specific interaction parameters are presented. Vapour pressure, density, and mean ionic activity coefficient data are used to determine the ion-ion and solvent-ion parameters, and mixed-salt electrolyte solutions (brines) are then treated predictively. We find that the resulting intermolecular potential models follow physical trends in terms of energies and ion sizes with a close relationship observed with well-established ionic diameters. A good description is obtained for the densities, mean ionic activity coefficients, and vapour pressures of the electrolyte solutions studied. The theory is also seen to provide excellent predictions of the osmotic coefficient and of the depression of the freezing temperature, and provides a qualitative estimate of the solvation free energy. The vapour pressure of aqueous brines is predicted accurately, as is the density of these solutions, although not at the highest pressures considered. Calculations for the vapour-liquid and liquid-liquid equilibria of salts in water+methanol and water+n-butan-1-ol are presented. In addition, it is shown that the salting-out of carbon dioxide in sodium chloride solutions is captured well using a predictive model.
Generalized fluid theory including non-Maxwellian kinetic effects
Izacard, Olivier
2016-01-01
The results obtained by the plasma physics community for the validation and the prediction of turbulence and transport in magnetized plasma come mainly from the use of very CPU-consuming particle-in-cell or (gyro)kinetic codes which naturally include non-Maxwellian kinetic effects. To date, fluid codes are not considered to be relevant for the description of these kinetic effects. Here, after revisiting the limitations of the current fluid theory developed in the 19th century, we generalize the fluid theory including kinetic effects such as non-Maxwellian super-thermal tails with as few fluid equations as possible. The collisionless and collisional fluid closures from the nonlinear Landau Fokker-Planck collision operator are shown for an arbitrary collisionality. Indeed, the first fluid models associated with two examples of collisionless fluid closures are obtained by assuming an analytic non-Maxwellian distribution function (e.g., the INMDF [O. Izacard, Phys. Plasmas 23, 082504 (2016)]). One of the main dif...
DEFF Research Database (Denmark)
Arya, Alay; Liang, Xiaodong; von Solms, Nicolas
2016-01-01
using various equations of state and empirical models. In the past few years, association models based on CPA and SAFT equations of state have been found to be promising models for studies of asphaltene precipitation. In this work, we compare asphaltene precipitation results obtained from different...
Neves, Catarina M S S; Held, Christoph; Mohammad, Sultan; Schleinitz, Miko; Coutinho, João A P; Freire, Mara G
2015-12-21
Due to scarce available experimental data, as well as due to the absence of predictive models, the influence of salts on the solubility of ionic liquids (ILs) in water is still poorly understood. To this end, this work addresses the solubility of the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4C1im][NTf2]), at 298.15 K and 0.1 MPa, in aqueous salt solutions (from 0.1 to 1.5 mol kg(-1)). At salt molalities higher than 0.2 mol kg(-1), all salts caused salting-out of [C4C1im][NTf2] from aqueous solution with their strength decreasing in the following order: Al2(SO4)3 > ZnSO4 > K3C6H5O7 > KNaC4H4O6 > K3PO4 > Mg(CH3CO2)2 > K2HPO4 > MgSO4 > KH2PO4 > KCH3CO2. Some of these salts lead however to the salting-in of [C4C1im][NTf2] in aqueous medium at salt molalities lower than 0.2 mol kg(-1). To attempt the development of a model able to describe the salt effects, comprising both the salting-in and salting-out phenomena observed, the electrolyte Perturbed-Chain Statistical Associating Fluid Theory (ePC-SAFT) was applied using ion-specific parameters. The gathered experimental data was modelled using ePC-SAFT parameters complemented by fitting a single binary parameter between K(+) and the IL-ions to the IL solubility in K3PO4 aqueous solutions. Based on this approach, the description of anion-specific salting-out effects of the remaining potassium salts was found to be in good agreement with experimental data. Remarkably, ePC-SAFT is even able to predict the salting-in effect induced by K2HPO4, based on the single K(+)/IL-ions binary parameter which was fitted to an exclusively salting-out effect promoted by K3PO4. Finally, ePC-SAFT was applied to predict the influence of other sodium salts on the [C4C1im][NTf2] solubility in water, with experimental data taken from literature, leading to an excellent description of the liquid-liquid phase behaviour.
Improved renormalization group theory for critical asymmetry of fluids.
Wang, Long; Zhao, Wei; Wu, Liang; Li, Liyan; Cai, Jun
2013-09-28
We develop an improved renormalization group (RG) approach incorporating the critical vapor-liquid equilibrium asymmetry. In order to treat the critical asymmetry of vapor-liquid equilibrium, the integral measure is introduced in the Landau-Ginzbug partition function to achieve a crossover between the local order parameter in Ising model and the density of fluid systems. In the implementation of the improved RG approach, we relate the integral measure with the inhomogeneous density distribution of a fluid system and combine the developed method with SAFT-VR (statistical associating fluid theory of variable range) equation of state. The method is applied to various fluid systems including square-well fluid, square-well dimer fluid and real fluids such as methane (CH4), ethane (C2H6), trifluorotrichloroethane (C2F3Cl3), and sulfur hexafluoride (SF6). The descriptions of vapor-liquid equilibria provided by the developed method are in excellent agreement with simulation and experimental data. Furthermore, the improved method predicts accurate and qualitatively correct behavior of coexistence diameter near the critical point and produces the non-classical 3D Ising criticality.
Simple bond length dependence: A correspondence between reactive fluid theories
Dyer, Kippi M.; Perkyns, John S.; Pettitt, B. M.
2005-06-01
Two elementary models of reactive fluids are examined, the first being a standard construction assuming molecular dissociation at infinite separation; the second is an open mixture of nondissociative molecules and free atoms in which the densities of free atoms and molecules are coupled. An approximation to the density of molecules, to low order in site density, is derived in terms of the classical associating fluid theory variously described by Wertheim [J. Chem. Phys. 87, 7323 (1987)] and Stell [Physica A 231, 1 (1996)]. The results are derived for a fluid of dimerizing hard spheres, and predict dependence of the molecular density on the total site density, the hard sphere diameter, and the bond length of the dimer. The results for the two reactive models are shown to be qualitatively similar, and lead to equivalent predictions of the molecular density for the infinitely short and infinitely long bond lengths.
Constraints on the effective fluid theory of stationary branes
Armas, Jay
2014-01-01
We develop further the effective fluid theory of stationary branes. This formalism applies to stationary blackfolds as well as to other equilibrium brane systems at finite temperature. The effective theory is described by a Lagrangian containing the information about the elastic dynamics of the brane embedding as well as the hydrodynamics of the effective fluid living on the brane. The Lagrangian is corrected order-by-order in a derivative expansion, where we take into account the dipole moment of the brane which encompasses finite-thickness corrections, including transverse spin. We describe how to extract the thermodynamics from the Lagrangian and we obtain constraints on the higher-derivative terms with one and two derivatives. These constraints follow by comparing the brane thermodynamics with the conserved currents associated with background Killing vector fields. In particular, we fix uniquely the one- and two-derivative terms describing the coupling of the transverse spin to the background space-time. ...
Bansal, Artee; Cox, Kenneth R; Chapman, Walter G
2016-01-01
A mixture of solvent particles with short-range, directional interactions and solute particles with short-range, isotropic interactions that can bond multiple times is of fundamental interest in understanding liquids and colloidal mixtures. Because of multi-body correlations predicting the structure and thermodynamics of such systems remains a challenge. Earlier Marshall and Chapman developed a theory wherein association effects due to interactions multiply the partition function for clustering of particles in a reference hard-sphere system. The multi-body effects are incorporated in the clustering process, which in their work was obtained in the absence of the bulk medium. The bulk solvent effects were then modeled approximately within a second order perturbation approach. However, their approach is inadequate at high densities and for large association strengths. Based on the idea that the clustering of solvent in a defined coordination volume around the solute is related to occupancy statistics in that def...
Study of high-pressure adsorption from supercritical fluids by the potential theory
DEFF Research Database (Denmark)
Monsalvo, Matias Alfonso; Shapiro, Alexander
2009-01-01
The multicomponent potential theory of adsorption (MPTA), which has been previously used to study low-pressure adsorption of subcritical fluids, is extended to adsorption equilibria from supercritical fluids up to high pressures. The MPTA describes an adsorbed phase as an inhomogeneous fluid...... with thermodynamic properties that depend on the distance from the solid surface (or position in the porous space). The description involves the two kinds of interactions present in the adsorbed fluid, i.e. the fluid-fluid and fluid-solid interactions. accounted for by means of an equation of state (Eo......S) and interaction potential functions, respectively. This makes it possible to generate the different MPTA models by combination of the relevant EoS/potentials. In the present work, the simplified perturbed-chain statistical associating fluid theory (sPC-SAFT) EoS is used for the thermodynamic description of both...
Bansal, Artee; Asthagiri, D; Cox, Kenneth R; Chapman, Walter G
2016-08-21
A mixture of solvent particles with short-range, directional interactions and solute particles with short-range, isotropic interactions that can bond multiple times is of fundamental interest in understanding liquids and colloidal mixtures. Because of multi-body correlations, predicting the structure and thermodynamics of such systems remains a challenge. Earlier Marshall and Chapman [J. Chem. Phys. 139, 104904 (2013)] developed a theory wherein association effects due to interactions multiply the partition function for clustering of particles in a reference hard-sphere system. The multi-body effects are incorporated in the clustering process, which in their work was obtained in the absence of the bulk medium. The bulk solvent effects were then modeled approximately within a second order perturbation approach. However, their approach is inadequate at high densities and for large association strengths. Based on the idea that the clustering of solvent in a defined coordination volume around the solute is related to occupancy statistics in that defined coordination volume, we develop an approach to incorporate the complete information about hard-sphere clustering in a bulk solvent at the density of interest. The occupancy probabilities are obtained from enhanced sampling simulations but we also develop a concise parametric form to model these probabilities using the quasichemical theory of solutions. We show that incorporating the complete reference information results in an approach that can predict the bonding state and thermodynamics of the colloidal solute for a wide range of system conditions.
Bansal, Artee; Asthagiri, D.; Cox, Kenneth R.; Chapman, Walter G.
2016-08-01
A mixture of solvent particles with short-range, directional interactions and solute particles with short-range, isotropic interactions that can bond multiple times is of fundamental interest in understanding liquids and colloidal mixtures. Because of multi-body correlations, predicting the structure and thermodynamics of such systems remains a challenge. Earlier Marshall and Chapman [J. Chem. Phys. 139, 104904 (2013)] developed a theory wherein association effects due to interactions multiply the partition function for clustering of particles in a reference hard-sphere system. The multi-body effects are incorporated in the clustering process, which in their work was obtained in the absence of the bulk medium. The bulk solvent effects were then modeled approximately within a second order perturbation approach. However, their approach is inadequate at high densities and for large association strengths. Based on the idea that the clustering of solvent in a defined coordination volume around the solute is related to occupancy statistics in that defined coordination volume, we develop an approach to incorporate the complete information about hard-sphere clustering in a bulk solvent at the density of interest. The occupancy probabilities are obtained from enhanced sampling simulations but we also develop a concise parametric form to model these probabilities using the quasichemical theory of solutions. We show that incorporating the complete reference information results in an approach that can predict the bonding state and thermodynamics of the colloidal solute for a wide range of system conditions.
Fluid Mechanics An Introduction to the Theory of Fluid Flows
Durst, Franz
2008-01-01
Advancements of fluid flow measuring techniques and of computational methods have led to new ways to treat laminar and turbulent flows. These methods are extensively used these days in research and engineering practise. This also requires new ways to teach the subject to students at higher educational institutions in an introductory manner. The book provides the knowledge to students in engineering and natural science needed to enter fluid mechanics applications in various fields. Analytical treatments are provided, based on the Navier-Stokes equations. Introductions are also given into numerical and experimental methods applied to flows. The main benefit the reader will derive from the book is a sound introduction into all aspects of fluid mechanics covering all relevant subfields.
Dujko, Sasa
2016-09-01
In this work we review the progress achieved over the last few decades in the fundamental kinetic theory of charged particle swarms with the focus on numerical techniques for the solution of Boltzmann's equation for electrons, as well as on the development of fluid models. We present a time-dependent multi term solution of Boltzmann's equation valid for electrons and positrons in varying configurations of electric and magnetic fields. The capacity of a theory and associated computer code will be illustrated by considering the heating mechanisms for electrons in radio-frequency electric and magnetic fields in a collision-dominated regime under conditions when electron transport is greatly affected by non-conservative collisions. The kinetic theory for solving the Boltzmann equation will be followed by a fluid equation description of charged particle swarms in both the hydrodynamic and non-hydrodynamic regimes, highlighting (i) the utility of momentum transfer theory for evaluating collisional terms in the balance equations and (ii) closure assumptions and approximations. The applications of this theory are split into three sections. First, we will present our 1.5D model of Resistive Plate Chambers (RPCs) which are used for timing and triggering purposes in many high energy physics experiments. The model is employed to study the avalanche to streamer transition in RPCs under the influence of space charge effects and photoionization. Second, we will discuss our high-order fluid model for streamer discharges. Particular emphases will be placed on the correct implementation of transport data in streamer models as well as on the evaluation of the mean-energy-dependent collision rates for electrons required as an input in the high-order fluid model. In the last segment of this work, we will present our model to study the avalanche to streamer transition in non-polar fluids. Using a Monte Carlo simulation technique we have calculated transport coefficients for electrons in
Critical asymmetry in renormalization group theory for fluids.
Zhao, Wei; Wu, Liang; Wang, Long; Li, Liyan; Cai, Jun
2013-06-21
The renormalization-group (RG) approaches for fluids are employed to investigate critical asymmetry of vapour-liquid equilibrium (VLE) of fluids. Three different approaches based on RG theory for fluids are reviewed and compared. RG approaches are applied to various fluid systems: hard-core square-well fluids of variable ranges, hard-core Yukawa fluids, and square-well dimer fluids and modelling VLE of n-alkane molecules. Phase diagrams of simple model fluids and alkanes described by RG approaches are analyzed to assess the capability of describing the VLE critical asymmetry which is suggested in complete scaling theory. Results of thermodynamic properties obtained by RG theory for fluids agree with the simulation and experimental data. Coexistence diameters, which are smaller than the critical densities, are found in the RG descriptions of critical asymmetries of several fluids. Our calculation and analysis show that the approach coupling local free energy with White's RG iteration which aims to incorporate density fluctuations into free energy is not adequate for VLE critical asymmetry due to the inadequate order parameter and the local free energy functional used in the partition function.
Investigating models for associating fluids using spectroscopy
DEFF Research Database (Denmark)
von Solms, Nicolas; Michelsen, Michael Locht; Passos, Claudia Pereira;
2005-01-01
Two equations of state (PC-SAFT and CPA) are used to predict the monomer fraction of pure associating fluids. The models each require five pure-component parameters usually obtained by fitting to experimental liquid density and vapor pressure data. Here we also incorporate monomer fractions...
Institute of Scientific and Technical Information of China (English)
SUN Zong-Li; KANG Yan-Shuang
2011-01-01
Classical density functional theory is used to study the associating Lennard Jones fluids in contact with spherical hard wall of different curvature radii. The interfacial properties including contact density and fluid-solid interfacial tension are investigated. The influences of associating energy, curvature of hard wall and the bulk density of Huids on these properties are analyzed in detail. The results may provide helpful clues to understand the interfacial properties of other complex fluids.%@@ Classical density functional theory is used to study the associating Lennard Jones fluids in contact with spherical hard wall of different curvature radii.The interfacial properties including contact density and fluid-solid intcrfacial tension are investigated.The influences of associating energy, curvature of hard wall and the hulk density of fluids on these properties are analyzed in detail.The results may provide helpful clues to understand the interfacial properties of other complex fluids.
The case for hyperbolic theories of dissipation in relativistic fluids
Anile, A M; Romano, V; Anile, Angelo Marcello; Pavon, Diego; Romano, Vittorio
1998-01-01
In this paper we higlight the fact that the physical content of hyperbolic theories of relativistic dissipative fluids is, in general, much broader than that of the hyperbolic ones. This is substantiated by presenting an ample range of dissipative fluids whose behavior noticeably departs from Navier-Stokes.
Towards Predictive Association Theories
DEFF Research Database (Denmark)
Kontogeorgis, Georgios; Tsivintzelis, Ioannis; Michelsen, Michael Locht
2011-01-01
Association equations of state like SAFT, CPA and NRHB have been previously applied to many complex mixtures. In this work we focus on two of these models, the CPA and the NRHB equations of state and the emphasis is on the analysis of their predictive capabilities for a wide range of applications...... and water–MEG–aliphatic hydrocarbons LLE using interaction parameters obtained from the binary data alone. Moreover, it is demonstrated that the NRHB equation of state is a versatile tool which can be employed equally well to mixtures with pharmaceuticals and solvents, including mixed solvents, as well...
Modern Fluid Dynamics Intermediate Theory and Applications
Kleinstreuer, Clement
2010-01-01
Features pedagogical elements that include consistent 50/50 physics-mathematics approach when introducing material, illustrating concepts, showing flow visualizations, and solving problems. This title intends to help serious undergraduate student solve basic fluid dynamics problems independently, and suggest system design improvements
Two-fluid theory of the drift kink instability
Energy Technology Data Exchange (ETDEWEB)
Daughton, William [Los Alamos National Laboratory, Los Alamos, New Mexico (United States)
1999-12-01
A simple two-fluid theory of the drift kink instability is developed. The validity of the theory is restricted to the regime where the ion gyroradius is small in comparison with the sheet thickness {rho}{sub i}<
Association theories for complex thermodynamics
DEFF Research Database (Denmark)
Kontogeorgis, Georgios; Rafiqul Gani
2013-01-01
Thermodynamics of complex systems (e.g. with associating molecules, multicomponent mixtures, multiphase equilibria, wide ranges of conditions, estimation of many different properties simultaneously) is a topic of great importance in chemical engineering and for a wide range of industrial applicat......Thermodynamics of complex systems (e.g. with associating molecules, multicomponent mixtures, multiphase equilibria, wide ranges of conditions, estimation of many different properties simultaneously) is a topic of great importance in chemical engineering and for a wide range of industrial...... applications. While specialized models can handle different cases, even complex ones, with the advent of powerful theories and computers there is the hope that a single or a few models could be suitable for a general modeling of complex thermodynamics. After more than 100 years with active use of thermodynamic...... promising direction for a general and useful for engineering purposes modeling of complex thermodynamics is via the use of association theories e.g. those based on chemical theory (like APACT), or on the lattice theory (like NRHB) or those based on perturbation theory (like SAFT and CPA). The purpose...
Pleural fluids associated with chest infection.
Quadri, Amal; Thomson, Anne H
2002-12-01
Pleural effusions are commonly associated with pneumonias and a small number of these progress to empyema. An understanding of the physiology and pathophysiology of pleural fluid aids the clinician in the management of empyema. There remains much debate about the optimal treatment of empyema in children. Early recognition of the condition is important since delayed therapy may result in unnecessary morbidity. Conventional management with high dose parenteral antibiotics and chest tube drainage remains the mainstay of therapy. However, this treatment modality may fail if the pleural fluid becomes viscous and loculated and, therefore, a more aggressive approach is required. Intrapleural fibrinolytic therapy has been shown to decrease the length of hospital stay and may reduce the need for surgical intervention. The prognosis in children with parapneumonic empyema is excellent with the vast majority retaining normal lung function at long term follow-up.
Electrorheological fluids modeling and mathematical theory
Růžička, Michael
2000-01-01
This is the first book to present a model, based on rational mechanics of electrorheological fluids, that takes into account the complex interactions between the electromagnetic fields and the moving liquid. Several constitutive relations for the Cauchy stress tensor are discussed. The main part of the book is devoted to a mathematical investigation of a model possessing shear-dependent viscosities, proving the existence and uniqueness of weak and strong solutions for the steady and the unsteady case. The PDS systems investigated possess so-called non-standard growth conditions. Existence results for elliptic systems with non-standard growth conditions and with a nontrivial nonlinear r.h.s. and the first ever results for parabolic systems with a non-standard growth conditions are given for the first time. Written for advanced graduate students, as well as for researchers in the field, the discussion of both the modeling and the mathematics is self-contained.
Archer, A J
2009-01-07
In recent years, a number of dynamical density functional theories (DDFTs) have been developed for describing the dynamics of the one-body density of both colloidal and atomic fluids. In the colloidal case, the particles are assumed to have stochastic equations of motion and theories exist for both the case when the particle motion is overdamped and also in the regime where inertial effects are relevant. In this paper, we extend the theory and explore the connections between the microscopic DDFT and the equations of motion from continuum fluid mechanics. In particular, starting from the Kramers equation, which governs the dynamics of the phase space probability distribution function for the system, we show that one may obtain an approximate DDFT that is a generalization of the Euler equation. This DDFT is capable of describing the dynamics of the fluid density profile down to the scale of the individual particles. As with previous DDFTs, the dynamical equations require as input the Helmholtz free energy functional from equilibrium density functional theory (DFT). For an equilibrium system, the theory predicts the same fluid one-body density profile as one would obtain from DFT. Making further approximations, we show that the theory may be used to obtain the mode coupling theory that is widely used for describing the transition from a liquid to a glassy state.
Perturbation theories for the thermodynamic properties of fluids and solids
Solana, J R
2013-01-01
This book, Perturbation Theories for the Thermodynamic Properties of Fluids and Solids, provides a comprehensive review of current perturbation theories-as well as integral equation theories and density functional theories-for the equilibrium thermodynamic and structural properties of classical systems. Emphasizing practical applications, the text avoids complex theoretical derivations as much as possible. It begins with discussions of the nature of intermolecular forces and simple potential models. The book also presents a summary of statistical mechanics concepts and formulae. In addition, i
Mathematical theory of compressible viscous fluids analysis and numerics
Feireisl, Eduard; Pokorný, Milan
2016-01-01
This book offers an essential introduction to the mathematical theory of compressible viscous fluids. The main goal is to present analytical methods from the perspective of their numerical applications. Accordingly, we introduce the principal theoretical tools needed to handle well-posedness of the underlying Navier-Stokes system, study the problems of sequential stability, and, lastly, construct solutions by means of an implicit numerical scheme. Offering a unique contribution – by exploring in detail the “synergy” of analytical and numerical methods – the book offers a valuable resource for graduate students in mathematics and researchers working in mathematical fluid mechanics. Mathematical fluid mechanics concerns problems that are closely connected to real-world applications and is also an important part of the theory of partial differential equations and numerical analysis in general. This book highlights the fact that numerical and mathematical analysis are not two separate fields of mathematic...
Vapour-to-Liquid Nucleation in Associating Lennard-Jones Fluids with Multiple Association Sites
Institute of Scientific and Technical Information of China (English)
FU Dong; LIAO Tao
2007-01-01
The excess Helmholtz free energy functional for associating Lennard-Jones (LJ) fluid is formulated in terms of a weighted density approximation for short-ranged interactions and a Weeks Chandler-Andersen approximation for long-range attraction. Within the framework of density functional theory, phase equilibria, vapour-liquid surface tension and vapour-liquid nucleation properties including the density profile, work of formation, excess number of particles and critical supersaturation are investigated for associating LJ fluids with different numbers of association sites (M=1,2,3,4) per particle. The influences of association energy and association sites on phase equilibria, surface tension and vapour-liquid nucleation properties are discussed.
Generalized fluid theory including non-Maxwellian kinetic effects
Izacard, Olivier
2016-01-01
The results obtained by the plasma physics community for the validation and the prediction of turbulence and transport in magnetized plasma come mainly from the use of very CPU-consuming particle-in-cell or (gyro)kinetic codes which naturally include non-Maxwellian kinetic effects. To date, fluid codes are not considered to be relevant for the description of these kinetic effects. Here, after revisiting the limitations of the current fluid theory developed in the 19th century, we generalize t...
Thermodynamics of perfect fluids from scalar field theory
Ballesteros, Guillermo; Pilo, Luigi
2016-01-01
The low-energy dynamics of relativistic continuous media is given by a shift-symmetric effective theory of four scalar fields. These scalars describe the embedding in spacetime of the medium and play the role of Stuckelberg fields for spontaneously broken spatial and time translations. Perfect fluids are selected imposing a stronger symmetry group or reducing the field content to a single scalar. We explore the relation between the field theory description of perfect fluids to thermodynamics. By drawing the correspondence between the allowed operators at leading order in derivatives and the thermodynamic variables, we find that a complete thermodynamic picture requires the four Stuckelberg fields. We show that thermodynamic stability plus the null energy condition imply dynamical stability. We also argue that a consistent thermodynamic interpretation is not possible if any of the shift symmetries is explicitly broken.
Theory of fluid slip in charged capillary nanopores
Catalano, J; Biesheuvel, P M
2016-01-01
Based on the capillary pore model (space-charge theory) for combined fluid and ion flow through cylindrical nanopores or nanotubes, we derive the continuum equations modified to include wall slip. We focus on the ionic conductance and streaming conductance, cross-coefficients of relevance for electrokinetic energy conversion and electro-osmotic pumping. We combine the theory with a Langmuir-Stern 1-pK charge regulation boundary condition resulting in a non-monotonic dependence of the cross-coefficients on salt concentration.
Mathematical Theory of Compressible Viscous Fluids: Analysis and Numerics
Feireisl, E. (Eduard); Karper, T.; Pokorný, M.
2016-01-01
This book offers an essential introduction to the mathematical theory of compressible viscous fluids. The main goal is to present analytical methods from the perspective of their numerical applications. Accordingly, we introduce the principal theoretical tools needed to handle well-posedness of the underlying Navier-Stokes system, study the problems of sequential stability, and, lastly, construct solutions by means of an implicit numerical scheme. Offering a unique contribution – by exploring...
Application of a density functional approach to nonuniform ionic fluids: the effect of association
Directory of Open Access Journals (Sweden)
J.Reszko-Zygmunt
2004-01-01
Full Text Available In the present paper we discuss a density functional approach for nonuniform ionic fluids, which takes into account the existence of ion pairs. The theory is based on a fundamental measure theory of hard-spheres, the theory of Gillespie et al., which leads to a more accurate description of the electrostatic part of the grand potential as well as on Wertheim's association theory. The results of model calculations indicate that the inclusion of the associative term in the grand potential leads to the structure of the double layer, which differs from the structure evaluated by neglecting the association. These differences are important at low temperatures only.
Associations Between Fluid Balance and Outcomes in Critically Ill Children
Alobaidi, Rashid; Morgan, Catherine; Basu, Rajit K.; Stenson, Erin; Featherstone, Robin; Majumdar, Sumit R.; Bagshaw, Sean M.
2017-01-01
Background: Fluid therapy is a mainstay during the resuscitation of critically ill children. After initial stabilization, excessive fluid accumulation may lead to complications of fluid overload, which has been independently associated with increased risk for mortality and major morbidity in critically ill children. Objectives: Perform an evidence synthesis to describe the methods used to measure fluid balance, define fluid overload, and evaluate the association between fluid balance and outcomes in critically ill children. Design: Systematic review and meta-analysis. Measurements: Fluid balance, fluid accumulation, and fluid overload as defined by authors. Methods: We will search Ovid MEDLINE, Ovid EMBASE, Cochrane Library, and ProQuest, Dissertations and Theses. In addition, we will search www.clinicaltrials.gov, World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) and the proceedings of selected key conferences for ongoing and completed studies. Search strategy will be done in consultation with a research librarian. Clinical trials and observational studies (from database inception to present) in patients (<25 years) admitted to pediatric intensive care units (PICUs) reporting fluid balance, fluid accumulation, or fluid overload, and associated outcomes will be included. Language will not be restricted. Two reviewers will independently screen studies and extract data. Primary outcome is mortality, and secondary outcomes encompass critical care resource utilization. Quality of evidence and risk of bias will be assessed using the Newcastle-Ottawa Scale (NOS). Results will be synthesized qualitatively and pooled for meta-analysis if possible. Limitations: Quality of the included studies; lack of randomized trials; high degrees of expected heterogeneity; and variations in definitions of fluid balance and fluid overload between studies. Conclusion: We will comprehensively appraise and summarize the evidence of the association between
A linear auroral current-voltage relation in fluid theory
Directory of Open Access Journals (Sweden)
J. Vedin
2004-04-01
Full Text Available Progress in our understanding of auroral currents and auroral electron acceleration has for decades been hampered by an apparent incompatibility between kinetic and fluid models of the physics involved. A well established kinetic model predicts that steady upward field-aligned currents should be linearly related to the potential drop along the field line, but collisionless fluid models that reproduce this linear current-voltage relation have not been found. Using temperatures calculated from the kinetic model in the presence of an upward auroral current, we construct here approximants for the parallel and perpendicular temperatures. Although our model is rather simplified, we find that the fluid equations predict a realistic large-scale parallel electric field and a linear current-voltage relation when these approximants are employed as nonlocal equations of state. This suggests that the concepts we introduce can be applied to the development of accurate equations of state for fluid simulations of auroral flux tubes.
Key words. Magnetospheric physics (auroral phenomena; magnetosphere-ionosphere interactions – Space plasma physics (kinetic and MHD theory
Unified dark fluid in Brans-Dicke theory
Energy Technology Data Exchange (ETDEWEB)
Tripathy, Sunil K. [Indira Gandhi Institute of Technology, Department of Physics, Dhenkanal, Odisha (India); Behera, Dipanjali [Government College of Engineering, Department of Physics, Kalahandi, Odisha (India); Mishra, Bivudutta [Birla Institute of Technology and Science-Pilani, Department of Mathematics, Hyderabad (India)
2015-04-01
Anisotropic dark energy cosmological models are constructed in the frame work of generalised Brans-Dicke theory with a self-interacting potential. A unified dark fluid characterised by a linear equation of state is considered as the source of dark energy. The shear scalar is considered to be proportional to the expansion scalar simulating an anisotropic relationship among the directional expansion rates. The dynamics of the universe in the presence of a unified dark fluid in anisotropic background have been discussed. The presence of an evolving scalar field makes it possible to get an accelerating phase of expansion even for a linear relationship among the directional Hubble rates. It is found that the anisotropy in expansion rates does not affect the scalar field, the self-interacting potential, but it controls the non-evolving part of the Brans-Dicke parameter. (orig.)
Institute of Scientific and Technical Information of China (English)
FU Dong; YAN Shu-Mei; WANG Xue-Min
2008-01-01
The excess Helmholtz free energy functional for four-site associating Lennard-Jones(LJ)fluid was formulated in terms of a modified fundamental measure theory for short-ranged interactions and a first-order mean-spherical approximation theory for long-ranged attraction.Within the framework of density functional theory,the thermodynamic properties including the average density isotherms,density profiles and fractions of not bonded monomers characterizing the coexistences between gas-like and liquid-like phases for capillary condensation,phase equilibria and equilibrium plate-fluid interfacial tensions were investigated.The influences of association energy,fluid-solid interaction and pore width on the inhomogeneous behavior of four-site associating LJ fluids confined in slit pores were discussed.
Janus fluid with fixed patch orientations: theory and simulations.
Maestre, Miguel Ángel G; Fantoni, Riccardo; Giacometti, Achille; Santos, Andrés
2013-03-07
We study thermophysical properties of a Janus fluid with constrained orientations, using analytical techniques and numerical simulations. The Janus character is modeled by means of a Kern-Frenkel potential where each sphere has one hemisphere of square-well and the other of hard-sphere character. The orientational constraint is enforced by assuming that each hemisphere can only point either North or South with equal probability. The analytical approach hinges on a mapping of the above Janus fluid onto a binary mixture interacting via a "quasi" isotropic potential. The anisotropic nature of the original Kern-Frenkel potential is reflected by the asymmetry in the interactions occurring between the unlike components of the mixture. A rational-function approximation extending the corresponding symmetric case is obtained in the sticky limit, where the square-well becomes infinitely narrow and deep, and allows a fully analytical approach. Notwithstanding the rather drastic approximations in the analytical theory, this is shown to provide a rather precise estimate of the structural and thermodynamical properties of the original Janus fluid.
A density functional theory for colloids with two multiple bonding associating sites.
Haghmoradi, Amin; Wang, Le; Chapman, Walter G
2016-06-22
Wertheim's multi-density formalism is extended for patchy colloidal fluids with two multiple bonding patches. The theory is developed as a density functional theory to predict the properties of an associating inhomogeneous fluid. The equation of state developed for this fluid depends on the size of the patch, and includes formation of cyclic, branched and linear clusters of associated species. The theory predicts the density profile and the fractions of colloids in different bonding states versus the distance from one wall as a function of bulk density and temperature. The predictions from our theory are compared with previous results for a confined fluid with four single bonding association sites. Also, comparison between the present theory and Monte Carlo simulation indicates a good agreement.
Fluid Registration of Diffusion Tensor Images Using Information Theory
Chiang, Ming-Chang; Leow, Alex D.; Klunder, Andrea D.; Dutton, Rebecca A.; Barysheva, Marina; Rose, Stephen E.; McMahon, Katie L.; de Zubicaray, Greig I.; Toga, Arthur W.; Thompson, Paul M.
2008-01-01
We apply an information-theoretic cost metric, the symmetrized Kullback-Leibler (sKL) divergence, or J-divergence, to fluid registration of diffusion tensor images. The difference between diffusion tensors is quantified based on the sKL-divergence of their associated probability density functions (PDFs). Three-dimensional DTI data from 34 subjects were fluidly registered to an optimized target image. To allow large image deformations but preserve image topology, we regularized the flow with a large-deformation diffeomorphic mapping based on the kinematics of a Navier-Stokes fluid. A driving force was developed to minimize the J-divergence between the deforming source and target diffusion functions, while reorienting the flowing tensors to preserve fiber topography. In initial experiments, we showed that the sKL-divergence based on full diffusion PDFs is adaptable to higher-order diffusion models, such as high angular resolution diffusion imaging (HARDI). The sKL-divergence was sensitive to subtle differences between two diffusivity profiles, showing promise for nonlinear registration applications and multisubject statistical analysis of HARDI data. PMID:18390342
Nucleation for Lennard-Jones Fluid by Density Functional Theory
Institute of Scientific and Technical Information of China (English)
FU Dong
2005-01-01
@@ A non-mean field density functional theory is employed to investigate the vapour-liquid nucleation. The excess Helmholtz free energy functional is formulated in terms of a local density approximation for short ranged repulsion and a density-gradient expansion for long-ranged attractions. An analytical expression for the direct correlation function of a Lennard-Jones fluid is utilized to take into account the effect of long-ranged attractions on intermolecular correlations. With the predicted bulk properties and surface tension as input, the nucleation properties including density profile, work of formation and number of particles at the reduced temperatures T* = 0.694 and 0.741 are inuestigated. The obtained number of particles in the critical nucleus agrees well with the simulation data.
Particle detachment from fluid interfaces: theory vs. experiments.
Anachkov, Svetoslav E; Lesov, Ivan; Zanini, Michele; Kralchevsky, Peter A; Denkov, Nikolai D; Isa, Lucio
2016-09-28
Microparticle adsorption and self-assembly at fluid interfaces are strongly affected by the particle three-phase contact angle θ. On the single-particle level, θ can be determined by several techniques, including colloidal-probe AFM, the gel-trapping technique (GTT) and the freeze-fracture shadow-casting (FreSCa) method. While GTT and FreSCa provide contact angle distributions measured over many particles, colloidal-probe AFM measures the wettability of an individual (specified) particle attached onto an AFM cantilever. In this paper, we extract θ for smooth microparticles through the analysis of force-distance curves upon particle approach and retraction from the fluid interface. From each retraction curve, we determine: (i) the maximal force, Fmax; (ii) the detachment distance, Dmax; and (iii) the work for quasistatic detachment, W. To relate Fmax, Dmax and W to θ, we developed a detailed theoretical model based on the capillary theory of flotation. The model was validated in three different ways. First, the contact angles, evaluated from Fmax, Dmax and W, are all close in value and were used to calculate the entire force-distance curves upon particle retraction without any adjustable parameters. Second, the model was successfully applied to predict the experimental force-distance curve of a truncated sphere, whose cut is positioned below the point of particle detachment from the interface. Third, our theory was confirmed by the excellent agreement between the particle contact angles obtained from the colloidal-probe AFM data and the ensemble-average contact angles measured by both GTT and FreSCa. Additionally, we devised a very accurate closed-form expression for W (representing the energy barrier for particle detachment), thus extending previous results in the literature.
Dynamic mean field theory for lattice gas models of fluid mixtures confined in mesoporous materials.
Edison, J R; Monson, P A
2013-11-12
We present the extension of dynamic mean field theory (DMFT) for fluids in porous materials (Monson, P. A. J. Chem. Phys. 2008, 128, 084701) to the case of mixtures. The theory can be used to describe the relaxation processes in the approach to equilibrium or metastable equilibrium states for fluids in pores after a change in the bulk pressure or composition. It is especially useful for studying systems where there are capillary condensation or evaporation transitions. Nucleation processes associated with these transitions are emergent features of the theory and can be visualized via the time dependence of the density distribution and composition distribution in the system. For mixtures an important component of the dynamics is relaxation of the composition distribution in the system, especially in the neighborhood of vapor-liquid interfaces. We consider two different types of mixtures, modeling hydrocarbon adsorption in carbon-like slit pores. We first present results on bulk phase equilibria of the mixtures and then the equilibrium (stable/metastable) behavior of these mixtures in a finite slit pore and an inkbottle pore. We then use DMFT to describe the evolution of the density and composition in the pore in the approach to equilibrium after changing the state of the bulk fluid via composition or pressure changes.
Dynamic self-consistent field theory for unentangled homopolymer fluids
Mihajlovic, Maja; Lo, Tak Shing; Shnidman, Yitzhak
2005-10-01
We present a lattice formulation of a dynamic self-consistent field (DSCF) theory that is capable of resolving interfacial structure, dynamics, and rheology in inhomogeneous, compressible melts and blends of unentangled homopolymer chains. The joint probability distribution of all the Kuhn segments in the fluid, interacting with adjacent segments and walls, is approximated by a product of one-body probabilities for free segments interacting solely with an external potential field that is determined self-consistently. The effect of flow on ideal chain conformations is modeled with finitely extensible, nonlinearly elastic dumbbells in the Peterlin approximation, and related to stepping probabilities in a random walk. Free segment and stepping probabilities generate statistical weights for chain conformations in a self-consistent field, and determine local volume fractions of chain segments. Flux balance across unit lattice cells yields mean field transport equations for the evolution of free segment probabilities and of momentum densities on the Kuhn length scale. Diffusive and viscous contributions to the fluxes arise from segmental hops modeled as a Markov process, with transition rates reflecting changes in segmental interaction, kinetic energy, and entropic contributions to the free energy under flow. We apply the DSCF equations to study both transient and steady-state interfacial structure, flow, and rheology in a sheared planar channel containing either a one-component melt or a phase-separated, two-component blend.
Talanquer, V
2005-04-15
In this study, we explore the global phase behavior of a simple model for self-associating fluids where association reduces the strength of the dispersion interactions between bonded particles. Recent research shows that this type of behavior likely explains the thermodynamic properties of strongly polar fluids and certain micellar solutions. Based on Wertheim's theory of associating liquids [M. S. Wertheim, J. Stat. Phys. 42, 459 (1986); 42, 477 (1986)], our model takes into account the effect that dissimilar particle interactions have on the equilibrium constant for self-association in the system. We find that weaker interactions between bonded molecules tend to favor the dissociation of chains at any temperature and density. This effect stabilizes a monomeric liquid phase at high densities, enriching the global phase behavior of the system. In particular, for systems in which the energy of mixing between bonded and unbonded species is positive, we find a triple point involving a vapor, a dense phase of chain aggregates, and a monomeric liquid. Phase coexistence between the vapor and the monomeric fluid is always more stable at temperatures above the triple point, but a highly associated fluid may exist as a metastable phase under these conditions. The presence of this metastable phase may explain the characteristic nucleation behavior of the liquid phase in strongly dipolar fluids.
Malijevský, Alexandr; Jackson, George; Varga, Szabolcs
2008-10-14
The extension of Onsager's second-virial theory [L. Onsager, Ann. N.Y. Acad. Sci. 51, 627 (1949)] for the orientational ordering of hard rods to mixtures of nonspherical hard bodies with finite length-to-breadth ratios is examined using the decoupling approximations of Parsons [Phys. Rev. A 19, 1225 (1979)] and Lee [J. Chem. Phys. 86, 6567 (1987); 89, 7036 (1988)]. Invariably the extension of the Parsons-Lee (PL) theory to mixtures has in the past involved a van der Waals one-fluid treatment in which the properties of the mixture are approximated by those of a reference one-component hard-sphere fluid with an effective diameter which depends on the composition of the mixture and the molecular parameters of the various components; commonly this is achieved by equating the molecular volumes of the effective hard sphere and of the components in the mixture and is referred to as the PL theory of mixtures. It is well known that a one-fluid treatment is not the most appropriate for the description of the thermodynamic properties of isotropic fluids, and inadequacies are often rectified with a many-fluid (MF) theory. Here, we examine MF theories which are developed from the virial theorem and the virial expansion of the Helmholtz free energy of anisotropic fluid mixtures. The use of the decoupling approximation of the pair distribution function at the level of a multicomponent hard-sphere reference system leads to our MF Parsons (MFP) theory of anisotropic mixtures. Alternatively the mapping of the virial coefficients of the hard-body mixtures onto those of equivalent hard-sphere systems leads to our MF Lee (MFL) theory. The description of the isotropic-nematic phase behavior of binary mixtures of hard Gaussian overlap particles is used to assess the adequacy of the four different theories, namely, the original second-virial theory of Onsager, the usual PL one-fluid theory, and the MF theories based on the Lee (MFL) and Parsons (MFP) approaches. A comparison with the
Turbulence theories and modelling of fluids and plasmas
Energy Technology Data Exchange (ETDEWEB)
Yoshizawa, Akira; Yokio, Nobumitsu [Institute of Industrial Science, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Itoh, Sanae-I [Research Institute for Applied Mechanics, Kyushu University, 87, Kasuga 816-8580 (Japan); Itoh, Kimitaka [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan)
2001-03-01
Theoretical and heuristic modelling methods are reviewed for studying turbulence phenomena of fluids and plasmas. Emphasis is placed on understanding of effects on turbulence characteristics due to inhomogeneities of field and plasma parameters. The similarity and dissimilarity between the methods for fluids and plasmas are sought in order to shed light on the properties that are shared or not by fluid and plasma turbulence. (author)
Turbulence theories and modelling of fluids and plasmas
Energy Technology Data Exchange (ETDEWEB)
Yoshizawa, Akira; Yokoi, Nobumitsu [Institute of Industrial Science, Univ. of Tokyo, Tokyo (Japan); Itoh, Sanae-I. [Research Institute for Applied Mechanics, Kyushu Univ., Kasuga, Fukuoka (Japan); Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan)
2001-04-01
Theoretical and heuristic modelling methods are reviewed for studying turbulence phenomena of fluids and plasmas. Emphasis is put on understanding of effects on turbulent characteristics due to inhomogeneities of field and plasma parameters. The similarity and dissimilarity between the methods for fluids and plasmas are sought in order to shed light on the properties that are shared or not by fluid and plasma turbulence. (author)
National Athletic Trainers' Association Position Statement: Fluid Replacement for Athletes.
Case, Douglas J.; Armstrong, Lawrence E.; Hillman, Susan K.; Montain, Scott J.; Reiff, Ralph V.; Rich, Brent S. E.; Roberts, William O.; Stone, Jennifer A.
2000-01-01
Presents recommendations from the National Athletic Trainers Association for optimizing the fluid replacement practices of athletes, explaining that dehydration can compromise athletic performance and increase the risk of exertional heat injury. Athletes must be educated about the risks of dehydration and overhydration. They must learn fluid…
Potential theory of adsorption for associating mixtures: possibilities and limitations
DEFF Research Database (Denmark)
Bjørner, Martin Gamel; Shapiro, Alexander; Kontogeorgis, Georgios
2013-01-01
The applicability of the Multicomponent Potential Theory of Adsorption (MPTA) for prediction of the adsorption equilibrium of several associating binary mixtures on different industrial adsorbents is investigated. In the MPTA the adsorbates are considered to be distributed fluids subject...... to describe the solid-fluid interactions. The potential is extended to include adsorbate-absorbent specific capacities rather than an adsorbent specific capacity. Correlations of pure component isotherms are generally excellent with individual capacities, although adsorption on silicas at different...... temperatures still poses a challenge. The quality of the correlations is usually independent on the applied EoS. Predictions for binary mixtures indicate that the MPTA+SRK is superior when adsorption occurs on non-polar or slightly polar adsorbents, while MPTA+CPA performs better for polar adsorbents, or when...
Problems associated with fluid biomarkers for Parkinson's disease.
Nyhlén, Jakob; Constantinescu, Radu; Zetterberg, Henrik
2010-10-01
This article focuses on biochemical markers that may be used in the diagnostics of Parkinson's disease and associated disorders, and to identify early cases and stratify patients into subgroups. We present an updated account of some currently available candidate fluid biomarkers, and discuss their diagnostic performance and limitations. We also discuss some of the general problems with Parkinson's disease biomarkers and possible ways of moving forward. It may be concluded that a diagnostically useful fluid biomarker for Parkinson's disease is yet to be identified. However, some interesting candidates exist and may prove useful in the future, alone or when analyzed together in patterns.
Extended Lubrication Theory: Estimation of Fluid Flow in Channels with Variable Geometry
Tavakol, Behrouz; Froehlicher, Guillaume; Stone, Howard A
2014-01-01
Lubrication theory is broadly applicable to the flow characterization of thin fluid films and the motion of particles near surfaces. We offer an extension to lubrication theory by considering higher-order terms of the analytical approximation to describe the fluid flow in a channel with features of a modest aspect ratio. We find good agreement between our analytical results and numerical simulations. We show that the extended lubrication theory is a robust tool for an accurate estimate of laminar fluid flow in channels with features on the order of the channel height, accounting for both smooth and sharp changes in geometry.
Complex fluids in biological systems experiment, theory, and computation
2015-01-01
This book serves as an introduction to the continuum mechanics and mathematical modeling of complex fluids in living systems. The form and function of living systems are intimately tied to the nature of surrounding fluid environments, which commonly exhibit nonlinear and history dependent responses to forces and displacements. With ever-increasing capabilities in the visualization and manipulation of biological systems, research on the fundamental phenomena, models, measurements, and analysis of complex fluids has taken a number of exciting directions. In this book, many of the world’s foremost experts explore key topics such as: Macro- and micro-rheological techniques for measuring the material properties of complex biofluids and the subtleties of data interpretation Experimental observations and rheology of complex biological materials, including mucus, cell membranes, the cytoskeleton, and blood The motility of microorganisms in complex fluids and the dynamics of active suspensions Challenges and solut...
Mirigian, Stephen; Schweizer, Kenneth S.
2014-01-01
Building on the elastically collective nonlinear Langevin equation theory developed for hard spheres in the preceding paper I, we propose and implement a quasi-universal theory for the alpha relaxation of thermal liquids based on mapping them to an effective hard sphere fluid via the dimensionless compressibility. The result is a zero adjustable parameter theory that can quantitatively address in a unified manner the alpha relaxation time over 14 or more decades. The theory has no singulariti...
Study on Surface Properties for Non-polar Fluids with Density Functional Theory
Institute of Scientific and Technical Information of China (English)
吴畏; 陆九芳; 付东; 刘金晨; 李以圭
2004-01-01
The density functional theory, simplified by the local density approximation and mean-field approximation, is applied to study the surface properties of pure non-polar fluids. A reasonable long rang correction is adopted to avoid the truncation of the potential. The perturbation theory is applied to establish the equation for the phase equilibrium, in which the hard-core chain fluid is as the reference fluid and the Yukawa potential is used as the perturbation term. Three parameters, elk, d and ms, are regressed from the vapor-liquid equilibria, and the surface properties, including density profile, surface tension and local surface tension profile are predicted with these parameters.
Gelled propellant flow: Boundary layer theory for power-law fluids in a converging planar channel
Kraynik, Andrew M.; Geller, A. S.; Glick, J. H.
1989-10-01
A boundary layer theory for the flow of power-law fluids in a converging planar channel has been developed. This theory suggests a Reynolds number for such flows, and following numerical integration, a boundary layer thickness. This boundary layer thickness has been used in the generation of a finite element mesh for the finite element code FIDAP. FIDAP was then used to simulate the flow of power-law fluids through a converging channel. Comparison of the analytic and finite element results shows the two to be in very good agreement in regions where entrance and exit effects (not considered in the boundary layer theory) can be neglected.
The force distribution probability function for simple fluids by density functional theory.
Rickayzen, G; Heyes, D M
2013-02-28
Classical density functional theory (DFT) is used to derive a formula for the probability density distribution function, P(F), and probability distribution function, W(F), for simple fluids, where F is the net force on a particle. The final formula for P(F) ∝ exp(-AF(2)), where A depends on the fluid density, the temperature, and the Fourier transform of the pair potential. The form of the DFT theory used is only applicable to bounded potential fluids. When combined with the hypernetted chain closure of the Ornstein-Zernike equation, the DFT theory for W(F) agrees with molecular dynamics computer simulations for the Gaussian and bounded soft sphere at high density. The Gaussian form for P(F) is still accurate at lower densities (but not too low density) for the two potentials, but with a smaller value for the constant, A, than that predicted by the DFT theory.
A continuum mechanical gradient theory with applications to fluid mechanics
Energy Technology Data Exchange (ETDEWEB)
Silber, G.; Alizadeh, M.; Benderoth, G. [Fachhochschule Frankfurt am Main (Germany). Lab. fuer Materialwissenschaften; Trostel, R
1998-11-01
A gradient theory of grade two based on an axiomatic conception of a nonlocal continuum theory for materials of grade n is presented. The total stress tensor of rank two in the equation of linear momentum contains two higher stress tensors of rank two and three. In the case of isotropic materials both the tensor of rank two and three are tensor-valued functions of the second order strain rate tensor and its first gradient so that the equation of motion is of order four. The necessary boundary conditions for real boundaries are generated by using so-called porosity tensors. This theory is applied to two experiments. To a velocity profile of a turbulent Couette flow of water and a Poiseuille flow of a blood like suspension. On the basis of these experimental data the material and porosity coefficients are identified by numerical algorithms like evolution strategies. (orig.) 23 refs.
Computational fluid dynamics in fire engineering theory, modelling and practice
Yuen, Kwok Kit
2009-01-01
Fire and combustion presents a significant engineering challenge to mechanical, civil and dedicated fire engineers, as well as specialists in the process and chemical, safety, buildings and structural fields. We are reminded of the tragic outcomes of 'untenable' fire disasters such as at King's Cross underground station or Switzerland's St Gotthard tunnel. In these and many other cases, computational fluid dynamics (CFD) is at the forefront of active research into unravelling the probable causes of fires and helping to design structures and systems to ensure that they are less likely in the f
Bianchi type VI1 cosmological model with wet dark fluid in scale invariant theory of gravitation
Mishra, B
2014-01-01
In this paper, we have investigated Bianchi type VIh, II and III cosmological model with wet dark fluid in scale invariant theory of gravity, where the matter field is in the form of perfect fluid and with a time dependent gauge function (Dirac gauge). A non-singular model for the universe filled with disorder radiation is constructed and some physical behaviors of the model are studied for the feasible VIh (h = 1) space-time.
Is there a "most perfect fluid" consistent with quantum field theory?
Cohen, Thomas D
2007-07-13
It was recently conjectured that the ratio of the shear viscosity to entropy density eta/s for any fluid always exceeds [formula: see text]. A theoretical counterexample to this bound can be constructed from a nonrelativistic gas by increasing the number of species in the fluid while keeping the dynamics essentially independent of the species type. The question of whether the underlying structure of relativistic quantum field theory generically inhibits the realization of such a system and thereby preserves the possibility of a universal bound is considered here. Using rather conservative assumptions, it is shown here that a metastable gas of heavy mesons in a particular controlled regime of QCD provides a realization of the counterexample and is consistent with a well-defined underlying relativistic quantum field theory. Thus, quantum field theory appears to impose no lower bound on eta/s, at least for metastable fluids.
grim: A Flexible, Conservative Scheme for Relativistic Fluid Theories
Chandra, Mani; Foucart, Francois; Gammie, Charles F.
2017-03-01
Hot, diffuse, relativistic plasmas such as sub-Eddington black-hole accretion flows are expected to be collisionless, yet are commonly modeled as a fluid using ideal general relativistic magnetohydrodynamics (GRMHD). Dissipative effects such as heat conduction and viscosity can be important in a collisionless plasma and will potentially alter the dynamics and radiative properties of the flow from that in ideal fluid models; we refer to models that include these processes as Extended GRMHD. Here we describe a new conservative code, grim, that enables all of the above and additional physics to be efficiently incorporated. grim combines time evolution and primitive variable inversion needed for conservative schemes into a single step using an algorithm that only requires the residuals of the governing equations as inputs. This algorithm enables the code to be physics agnostic as well as flexibility regarding time-stepping schemes. grim runs on CPUs, as well as on GPUs, using the same code. We formulate a performance model and use it to show that our implementation runs optimally on both architectures. grim correctly captures classical GRMHD test problems as well as a new suite of linear and nonlinear test problems with anisotropic conduction and viscosity in special and general relativity. As tests and example applications, we resolve the shock substructure due to the presence of dissipation, and report on relativistic versions of the magneto-thermal instability and heat flux driven buoyancy instability, which arise due to anisotropic heat conduction, and of the firehose instability, which occurs due to anisotropic pressure (i.e., viscosity). Finally, we show an example integration of an accretion flow around a Kerr black hole, using Extended GRMHD.
A Thermodynamic Model for Square-well Chain Fluid: Theory and Monte Carlo Simulation
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
A thermodynamic model for the freely jointed square-well chain fluids was developed based on the thermodynamic perturbation theory of Barker-Henderson, Zhang and Wertheim. In this derivation Zhang's expressions for square-well monomers improved from Barker-Henderson compressibility approximation were adopted as the reference fluid, and Wertheim＇s polymerization method was used to obtain the free energy term due to the bond connectivity. An analytic expression for the Helmholtz free energy of the square-well chain fluids was obtained. The expression without adjustable parameters leads to the thermodynamic consistent predictions of the compressibility factors, residual internal energy and constant-volume heat capacity for dimer,4-mer, 8-mer and 16-mer square-well fluids. The results are in good agreement with the Monte Carlo simulation. To obtain the MC data of residual internal energy and the constant-volume heat capacity needed, NVT MC simulations were performed for these square-well chain fluids.
Cerebrospinal fluid neopterin and cryopyrin-associated periodic syndrome.
Serrano, Mercedes; Ormazábal, Aida; Antón, Jordi; Aróstegui, Juan I; García-Cazorla, Angels
2009-12-01
Cryopyrin-associated periodic syndrome is a category of autoinflammatory disorders caused by mutations of the NLRP3 gene, with chronic infantile neurologic cutaneous and articular syndrome being the severest clinical phenotype. Various pterins have been reported as mediating immunologic functions in the central nervous system, but to date studies of pterin cerebrospinal fluid (CSF) values and cryopyrin-associated periodic syndrome have been lacking. A 2-year-old child was affected with a severe atypical form of cryopyrin-associated periodic syndrome, suspected based on the analysis of neopterin in CSF. He initially presented isolated neurologic manifestations mimicking a neuroregressive disorder. Blood and CSF analyses did not present any routine inflammatory markers, but CSF neopterin was elevated. Later, the patient developed arthritis and recurrent episodes of fever, and the cryopyrin-associated periodic syndrome diagnosis was confirmed by genetic studies. Neopterin was the most altered indicator over the time. Child neurologists should be on the alert when unexplained neurologic signs appear, giving consideration to the possibility of inflammatory or immune-mediated diseases. The present case demonstrates the clinical utility of measurement of CSF neopterin levels in screening for these immune-mediated diseases, especially when neurologic symptoms are associated with normal results on routine CSF tests.
Scaled Particle Theory for Multicomponent Hard Sphere Fluids Confined in Random Porous Media.
Chen, W; Zhao, S L; Holovko, M; Chen, X S; Dong, W
2016-06-23
The formulation of scaled particle theory (SPT) is presented for a quite general model of fluids confined in a random porous media, i.e., a multicomponent hard sphere (HS) fluid in a multicomponent hard sphere or a multicomponent overlapping hard sphere (OHS) matrix. The analytical expressions for pressure, Helmholtz free energy, and chemical potential are derived. The thermodynamic consistency of the proposed theory is established. Moreover, we show that there is an isomorphism between the SPT for a multicomponent system and that for a one-component system. Results from grand canonical ensemble Monte Carlo simulations are also presented for a binary HS mixture in a one-component HS or a one-component OHS matrix. The accuracy of various variants derived from the basic SPT formulation is appraised against the simulation results. Scaled particle theory, initially formulated for a bulk HS fluid, has not only provided an analytical tool for calculating thermodynamic properties of HS fluid but also helped to gain very useful insight for elaborating other theoretical approaches such as the fundamental measure theory (FMT). We expect that the general SPT for multicomponent systems developed in this work can contribute to the study of confined fluids in a similar way.
Density Functional Theory Approach for Charged Hard Sphere Fluids Confined in Spherical Micro-Cavity
Institute of Scientific and Technical Information of China (English)
KANG Yan-Shuang; WANG Hai-Jun
2009-01-01
Within the framework of the density functional theory for classical fluids,the equilibrium density profiles of charged hard sphere fluid confined in micro-cavity are studied by means of the modified fundamental measure theory.The dimension of micro-cavity,the charge of hard sphere and the applied electric field are found to have significant effects on the density profiles.In particular,it is shown that Coulomb interaction,excluded volume interaction and applied electric Geld play the central role in controlling the aggregated structure of the system.
Structures and surface tensions of fluids near solid surfaces: an integral equation theory study.
Xu, Mengjin; Zhang, Chen; Du, Zhongjie; Mi, Jianguo
2012-06-07
In this work, integral equation theory is extended to describe the structures and surface tensions of confined fluids. To improve the accuracy of the equation, a bridge function based on the fundamental measure theory is introduced. The density profiles of the confined Lennard-Jones fluids and water are calculated, which are in good agreement with simulation data. On the basis of these density profiles, the grand potentials are then calculated using the density functional approach, and the corresponding surface tensions are predicted, which reproduce the simulation data well. In particular, the contact angles of water in contact with both hydrophilic and hydrophobic walls are evaluated.
DEFF Research Database (Denmark)
Tsivintzelis, Ioannis; Kontogeorgis, Georgios
2012-01-01
The cubic-plus-association (CPA) model is an equation of state (EoS) that combines the Soave–Redlich–Kwong (SRK) equation with the association term from Wertheim’s theory as used in statistical associating fluid theory (SAFT). In the form used here, the CPA EoS does not include separate terms....... The capabilities of the model are illustrated in the first two case studies: the phase behavior of mixtures used in the oxidation of 2-octanol in supercritical CO2 and the investigation of systems containing acetone, methanol, water, chloroform, and methyl acetate. In each case, both correlations of vapor...
Institute of Scientific and Technical Information of China (English)
李卫华; 诸蔚朝; 马红孺
2003-01-01
One component hard-sphere fluid confined in two planar hard walls is studied by means of density functional theory with Rosenfeld functional and molecular dynamics simulation. The validity of the Rosenfeld functional is examined. Chemical potential, grand potential and free energy as functions of the wall separation are obtained.
On wave propagation characteristics in fluid saturated porous materials by a nonlocal Biot theory
Tong, Lihong; Yu, Yang; Hu, Wentao; Shi, Yufeng; Xu, Changjie
2016-09-01
A nonlocal Biot theory is developed by combing Biot theory and nonlocal elasticity theory for fluid saturated porous material. The nonlocal parameter is introduced as an independent variable for describing wave propagation characteristics in poroelastic material. A physical insight on nonlocal term demonstrates that the nonlocal term is a superposition of two effects, one is inertia force effect generated by fluctuation of porosity and the other is pore size effect inherited from nonlocal constitutive relation. Models for situations of excluding fluid nonlocal effect and including fluid nonlocal effect are proposed. Comparison with experiment confirms that model without fluid nonlocal effect is more reasonable for predicting wave characteristics in saturated porous materials. The negative dispersion is observed theoretically which agrees well with the published experimental data. Both wave velocities and quality factors as functions of frequency and nonlocal parameter are examined in practical cases. A few new physical phenomena such as backward propagation and disappearance of slow wave when exceeding critical frequency and disappearing shear wave in high frequency range, which were not predicted by Biot theory, are demonstrated.
Hypersurface-homogeneous Universe filled with perfect fluid in $f (R, T)$ theory of gravity
Indian Academy of Sciences (India)
A Y SHAIKH; S D KATORE
2016-12-01
The exact solutions of the field equations with respect to hypersurface-homogeneous Universe filled with perfect fluid in the framework of $f (R, T)$ theory of gravity (Harko et al, \\emph{Phys. Rev.} D 84, 024020 (2011)) is derived. The physical behaviour of the cosmological model is studied.
Comparison of Theories of Anisotropy in Transformer Oil-Based Magnetic Fluids
Directory of Open Access Journals (Sweden)
Jozef Kudelcik
2013-01-01
Full Text Available The external magnetic field in transformer oil-based magnetic fluids leads to the aggregation of magnetic nanoparticles and formation of clusters. These aggregations are the result of the interaction between the external magnetic field and the magnetic moments of the nanoparticles occurs. However, the temperature of magnetic fluids has also very important influence on the structural changes because the mechanism of thermal motion acts against the cluster creation. The acoustic spectroscopy was used to study the anisotropy of transformer oil-based magnetic fluids upon the effect of an external magnetic field and temperature. In present the anisotropy of the magnetic fluids can be described by two theories. Taketomi theory assumes the existence of spherical clusters. These clusters form long chains, aligned in a magnetic field direction. Shliomis in his theory supposed that only nanoparticles formed chains. A comparison of the experimental results with the predictions of the Taketomi theory allowed a determination of the cluster radius and the number density of the colloidal particles. The proportions of the acoustic wave energy used for excitation of the translational and rotational motion were determined.
Zhao, HongSheng
2008-01-01
Empirical theories of Dark Matter like MOND gravity and of Dark Energy like f(R) gravity were motivated by astronomical data. But could these theories be branches rooted from a more general hence natural framework? Here we propose the natural Lagrangian of such a framework based on simple dimensional analysis and co-variant symmetry requirements, and explore various outcomes in a top-down fashion. Our framework preserves the co-variant formulation of GR, but allows the expanding physical metric be bent by a single new species of Dark Fluid flowing in space-time. Its non-uniform stress tensor and current vector are simply functions of a vector field of variable norm, resembling the 4-vector electromagnetic potential description for the photon fluid, but is dark (e.g., by very early decoupling from the baryon-radiation fluid). The Dark Fluid framework naturally branches into a continuous spectrum of theories with Dark Energy and Dark Matter effects, including the $f(R)$ gravity, TeVeS-like theories, Einstein-Ae...
Gögelein, Christoph; Romano, Flavio; Sciortino, Francesco; Giacometti, Achille
2012-03-01
We study the Kern-Frenkel model for patchy colloids using Barker-Henderson second-order thermodynamic perturbation theory. The model describes a fluid where hard sphere particles are decorated with one patch, so that they interact via a square-well potential if they are sufficiently close one another, and if patches on each particle are properly aligned. Both the gas-liquid and fluid-solid phase coexistences are computed and contrasted against corresponding Monte Carlo simulations results. We find that the perturbation theory describes rather accurately numerical simulations all the way from a fully covered square-well potential down to the Janus limit (half coverage). In the region where numerical data are not available (from Janus to hard-spheres), the method provides estimates of the location of the critical lines that could serve as a guideline for further efficient numerical work at these low coverages. A comparison with other techniques, such as integral equation theory, highlights the important aspect of this methodology in the present context.
Kou, Jisheng
2014-01-01
The gradient theory for the surface tension of simple fluids and mixtures is rigorously analyzed based on mathematical theory. The finite element approximation of surface tension is developed and analyzed, and moreover, an adaptive finite element method based on a physical-based estimator is proposed and it can be coupled efficiently with Newton\\'s method as well. The numerical tests are carried out both to verify the proposed theory and to demonstrate the efficiency of the proposed method. © 2013 Elsevier B.V. All rights reserved.
Bianchi Type VI1 Viscous Fluid Cosmological Model in Wesson´s Theory of Gravitation
Khadekar, G. S.; Avachar, G. R.
2007-03-01
Field equations of a scale invariant theory of gravitation proposed by Wesson [1, 2] are obtained in the presence of viscous fluid with the aid of Bianchi type VIh space-time with the time dependent gauge function (Dirac gauge). It is found that Bianchi type VIh (h = 1) space-time with viscous fluid is feasible in this theory, whereas Bianchi type VIh (h = -1, 0) space-times are not feasible in this theory, even in the presence of viscosity. For the feasible case, by assuming a relation connecting viscosity and metric coefficient, we have obtained a nonsingular-radiating model. We have discussed some physical and kinematical properties of the models.
Energy Technology Data Exchange (ETDEWEB)
Kakad, Amar [Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto 611-0011 (Japan); Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410-218 (India); Omura, Yoshiharu [Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto 611-0011 (Japan); Kakad, Bharati [Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410-218 (India)
2013-06-15
We perform one-dimensional fluid simulation of ion acoustic (IA) solitons propagating parallel to the magnetic field in electron-ion plasmas by assuming a large system length. To model the initial density perturbations (IDP), we employ a KdV soliton type solution. Our simulation demonstrates that the generation mechanism of IA solitons depends on the wavelength of the IDP. The short wavelength IDP evolve into two oppositely propagating identical IA solitons, whereas the long wavelength IDP develop into two indistinguishable chains of multiple IA solitons through a wave breaking process. The wave breaking occurs close to the time when electrostatic energy exceeds half of the kinetic energy of the electron fluid. The wave breaking amplitude and time of its initiation are found to be dependent on characteristics of the IDP. The strength of the IDP controls the number of IA solitons in the solitary chains. The speed, width, and amplitude of IA solitons estimated during their stable propagation in the simulation are in good agreement with the nonlinear fluid theory. This fluid simulation is the first to confirm the validity of the general nonlinear fluid theory, which is widely used in the study of solitary waves in laboratory and space plasmas.
Toward Quantitative Coarse-Grained Models of Lipids with Fluids Density Functional Theory.
Frink, Laura J Douglas; Frischknecht, Amalie L; Heroux, Michael A; Parks, Michael L; Salinger, Andrew G
2012-04-10
We describe methods to determine optimal coarse-grained models of lipid bilayers for use in fluids density functional theory (fluids-DFT) calculations. Both coarse-grained lipid architecture and optimal parametrizations of the models based on experimental measures are discussed in the context of dipalmitoylphosphatidylcholine (DPPC) lipid bilayers in water. The calculations are based on a combination of the modified-iSAFT theory for bonded systems and an accurate fundamental measures theory (FMT) for hard sphere reference fluids. We furthermore discuss a novel approach for pressure control in the fluids-DFT calculations that facilitates both partitioning studies and zero tension control for the bilayer studies. A detailed discussion of the numerical implementations for both solvers and pressure control capabilities are provided. We show that it is possible to develop a coarse-grained lipid bilayer model that is consistent with experimental properties (thickness and area per lipid) of DPPC provided that the coarse-graining is not too extreme. As a final test of the model, we find that the predicted area compressibility moduli and lateral pressure profiles of the optimized models are in reasonable agreement with prior results.
Edison, John R; Monson, Peter A
2014-07-14
Recently we have developed a dynamic mean field theory (DMFT) for lattice gas models of fluids in porous materials [P. A. Monson, J. Chem. Phys. 128(8), 084701 (2008)]. The theory can be used to describe the relaxation processes in the approach to equilibrium or metastable states for fluids in pores and is especially useful for studying system exhibiting adsorption/desorption hysteresis. In this paper we discuss the extension of the theory to higher order by means of the path probability method (PPM) of Kikuchi and co-workers. We show that this leads to a treatment of the dynamics that is consistent with thermodynamics coming from the Bethe-Peierls or Quasi-Chemical approximation for the equilibrium or metastable equilibrium states of the lattice model. We compare the results from the PPM with those from DMFT and from dynamic Monte Carlo simulations. We find that the predictions from PPM are qualitatively similar to those from DMFT but give somewhat improved quantitative accuracy, in part due to the superior treatment of the underlying thermodynamics. This comes at the cost of greater computational expense associated with the larger number of equations that must be solved.
Azma, Sahra; Rezazadeh, Ghader; Shabani, Rasoul; Alizadeh-Haghighi, Elnaz
2016-06-01
Viscous damping is a dominant source of energy dissipation in laterally oscillating micro-structures. In micro-resonators in which the characteristic dimensions are comparable to the dimensions of the fluid molecules, the assumption of the continuum fluid theory is no longer justified and the use of micro-polar fluid theory is indispensable. In this paper a mathematical model was presented in order to predict the viscous fluid damping in a laterally oscillating finger of a micro-resonator considering micro-polar fluid theory. The coupled governing partial differential equations of motion for the vibration of the finger and the micro-polar fluid field have been derived. Considering spin and no-spin boundary conditions, the related shape functions for the fluid field were presented. The obtained governing differential equations with time varying boundary conditions have been transformed to an enhanced form with homogenous boundary conditions and have been discretized using a Galerkin-based reduced order model. The effects of physical properties of the micro-polar fluid and geometrical parameters of the oscillating structure on the damping ratio of the system have been investigated.
Institute of Scientific and Technical Information of China (English)
Sahra Azma; Ghader Rezazadeh; Rasoul Shabani; Elnaz Alizadeh-Haghighi
2016-01-01
Viscous damping is a dominant source of energy dissipation in laterally oscillating micro-structures. In micro-resonators in which the characteristic dimensions are compa-rable to the dimensions of the fluid molecules, the assumption of the continuum fluid theory is no longer justified and the use of micro-polar fluid theory is indispensable. In this paper a mathematical model was presented in order to predict the viscous fluid damping in a laterally oscillating finger of a micro-resonator considering micro-polar fluid theory. The coupled governing partial differential equations of motion for the vibration of the finger and the micro-polar fluid field have been derived. Considering spin and no-spin boundary conditions, the related shape functions for the fluid field were presented. The obtained governing differential equations with time varying boundary conditions have been trans-formed to an enhanced form with homogenous boundary conditions and have been discretized using a Galerkin-based reduced order model. The effects of physical properties of the micro-polar fluid and geometrical parameters of the oscillat-ing structure on the damping ratio of the system have been investigated.
DEFF Research Database (Denmark)
Hjortrup, Peter Buhl; Haase, Nicolai; Wetterslev, Jørn;
2016-01-01
PURPOSE: Fluid resuscitation is a key intervention in patients with sepsis and circulatory impairment. The recommendations for continued fluid therapy in sepsis are vague, which may result in differences in clinical practice. We aimed to evaluate associations between hospital and patient...... characteristics and fluid resuscitation volumes in ICU patients with severe sepsis. METHODS: We explored the 6S trial database of ICU patients with severe sepsis needing fluid resuscitation randomised to hydroxyethyl starch 130/0.42 vs. Ringer's acetate. Our primary outcome measure was fluid resuscitation volume......, lower respiratory SOFA subscore and surgery were all independently associated with increased fluid resuscitation volumes. CONCLUSIONS: Hospital characteristics adjusted for patient baseline values were associated with differences in fluid resuscitation volumes given in the first 3 days of severe sepsis...
Cerebrospinal fluid dynamics in Chiari malformation associated with syringomyelia
Institute of Scientific and Technical Information of China (English)
LIU Bin; WANG Zhen-yu; XIE Jing-cheng; HAN Hong-bin; PEI Xin-long
2007-01-01
Background About 50%-70% of patients with Chiari malformation I (CMI) presented with syringomyelia (SM), which is supposed to be related to abnormal cerebrospinal fluid (CSF) flow around the foramen magnum. The aim of this study was to investigate the cerebrospinal fluid dynamics at levels of the aqueduct and upper cervical spine in patients with CMI associated with SM, and to discuss the possible mechanism of formation of SM.Methods From January to April 2004, we examined 10 adult patients with symptomatic CMI associated with SM and 10 healthy volunteers by phase-contrast MRI. CSF flow patterns were evaluated at seven regions of interest (ROI): the aqueduct and ventral and dorsal subarachnoid spaces of the spine at levels of the cerebellar tonsil, C2-3, and C5-6. The CSF flow waveforms were analyzed by measuring CSF circulation time, durations and maximum velocities of cranial- and caudal-directed flows, and the ratio between the two maximum velocities. Data were analyzed by ttest using SPSS 11.5.Results We found no definite communication between the fourth ventricle and syringomyelia by MRI in the 10 patients.In both the groups, we observed cranial-directed flow of CSF in the early cardiac systolic phase, which changed the direction from cranial to caudal from the middle systolic phase to the early diastolic phase, and then turned back in cranial direction in the late diastolic phase. The CSF flow disappeared at the dorsal ROI at the level of C2-3 in 3 patients and 1 volunteer, and at the level of C5-6 in 6 patients and 3 volunteers. The durations of CSF circulation at all the ROIs were significantly shorter in the patients than those in the healthy volunteers (P=0.014 at the midbrain aqueduct, P=0.019 at the inferior margin of the cerebellar tonsil, P=0.014 at the level of C2-3, and P=0.022 at the level of C5-6). No significant difference existed between the two groups in the initial point and duration of the caudal-directed CSF flow during a cardiac cycle at
Theory of wetting-induced fluid entrainment by advancing contact lines on dry surfaces.
Ledesma-Aguilar, R; Hernández-Machado, A; Pagonabarraga, I
2013-06-28
We report on the onset of fluid entrainment when a contact line is forced to advance over a dry solid of arbitrary wettability. We show that entrainment occurs at a critical advancing speed beyond which the balance between capillary, viscous, and contact-line forces sustaining the shape of the interface is no longer satisfied. Wetting couples to the hydrodynamics by setting both the morphology of the interface at small scales and the viscous friction of the front. We find that the critical deformation that the interface can sustain is controlled by the friction at the contact line and the viscosity contrast between the displacing and displaced fluids, leading to a rich variety of wetting-entrainment regimes. We discuss the potential use of our theory to measure contact-line forces using atomic force microscopy and to study entrainment under microfluidic conditions exploiting colloid-polymer fluids of ultralow surface tension.
Thermodynamic of fluids from a general equation of state: The molecular discrete perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Gámez, Francisco, E-mail: fgammar@upo.es [C/ Clavel 101, Mairena del Aljarafe, 41927 Seville (Spain)
2014-06-21
An extensive generalisation of the discrete perturbation theory for molecular multipolar non-spherical fluids is presented. An analytical expression for the Helmholtz free energy for an equivalent discrete potential is given as a function of density, temperature, and intermolecular parameters with implicit shape and multipolar dependence. By varying the intermolecular parameters through their geometrical and multipolar dependence, a set of molecular fluids are considered and their vapor–liquid phase diagrams are tested against available simulation data. Concretely, multipolar and non-polar Kihara and chainlike fluids are tested and it is found that this theoretical approach is able to reproduce qualitatively and quantitatively well the Monte Carlo data for the selected molecular potentials, except near the critical region.
Device modeling of superconductor transition edge sensors based on the two-fluid theory
Wang, Tian-Shun; Zhu, Qing-Feng; Wang, Jun-Xian; Li, Tie-Fu; Liu, Jian-She; Chen, Wei; Zhou, Xingxiang
2012-01-01
In order to support the design and study of sophisticated large scale transition edge sensor (TES) circuits, we use basic SPICE elements to develop device models for TESs based on the superfluid-normal fluid theory. In contrast to previous studies, our device model is not limited to small signal simulation, and it relies only on device parameters that have clear physical meaning and can be easily measured. We integrate the device models in design kits based on powerful EDA tools such as CADENCE and OrCAD, and use them for versatile simulations of TES circuits. Comparing our simulation results with published experimental data, we find good agreement which suggests that device models based on the two-fluid theory can be used to predict the behavior of TES circuits reliably and hence they are valuable for assisting the design of sophisticated TES circuits.
A general theory of non-equilibrium dynamics of lipid-protein fluid membranes
DEFF Research Database (Denmark)
Lomholt, Michael Andersen; Hansen, Per Lyngs; Miao, L.
2005-01-01
We present a general and systematic theory of non-equilibrium dynamics of multi-component fluid membranes, in general, and membranes containing transmembrane proteins, in particular. Developed based on a minimal number of principles of statistical physics and designed to be a meso/macroscopic-sca......-equilibrium phenomena in a range of membrane systems, as discussions in the paper of a few limit cases demonstrate. © EDP Sciences / Società Italiana di Fisica / Springer-Verlag 2005....
The Two Fluid Drop Snap-off Problem: Experiments and Theory
1999-01-01
We address the dynamics of a drop with viscosity $\\lambda \\eta$ breaking up inside another fluid of viscosity $\\eta$. For $\\lambda=1$, a scaling theory predicts the time evolution of the drop shape near the point of snap-off which is in excellent agreement with experiment and previous simulations of Lister and Stone. We also investigate the $\\lambda$ dependence of the shape and breaking rate.
The Two Fluid Drop Snap-off Problem Experiments and Theory
Cohen, I; Eggers, J; Nagel, S R; Cohen, Itai; Brenner, Michael P.; Eggers, Jens; Nagel, Sidney R.
1999-01-01
We address the dynamics of a drop with viscosity $\\lambda \\eta$ breaking up inside another fluid of viscosity $\\eta$. For $\\lambda=1$, a scaling theory predicts the time evolution of the drop shape near the point of snap-off which is in excellent agreement with experiment and previous simulations of Lister and Stone. We also investigate the $\\lambda$ dependence of the shape and breaking rate.
Pressure wave propagation in fluid-filled co-axial elastic tubes. Part 1: Basic theory.
Berkouk, K; Carpenter, P W; Lucey, A D
2003-12-01
Our work is motivated by ideas about the pathogenesis of syringomyelia. This is a serious disease characterized by the appearance of longitudinal cavities within the spinal cord. Its causes are unknown, but pressure propagation is probably implicated. We have developed an inviscid theory for the propagation of pressure waves in co-axial, fluid-filled, elastic tubes. This is intended as a simple model of the intraspinal cerebrospinal-fluid system. Our approach is based on the classic theory for the propagation of longitudinal waves in single, fluid-filled, elastic tubes. We show that for small-amplitude waves the governing equations reduce to the classic wave equation. The wave speed is found to be a strong function of the ratio of the tubes' cross-sectional areas. It is found that the leading edge of a transmural pressure pulse tends to generate compressive waves with converging wave fronts. Consequently, the leading edge of the pressure pulse steepens to form a shock-like elastic jump. A weakly nonlinear theory is developed for such an elastic jump.
Energy Technology Data Exchange (ETDEWEB)
Kok Yan Chan, G.; Sclavounos, P. D.; Jonkman, J.; Hayman, G.
2015-04-02
A hydrodynamics computer module was developed for the evaluation of the linear and nonlinear loads on floating wind turbines using a new fluid-impulse formulation for coupling with the FAST program. The recently developed formulation allows the computation of linear and nonlinear loads on floating bodies in the time domain and avoids the computationally intensive evaluation of temporal and nonlinear free-surface problems and efficient methods are derived for its computation. The body instantaneous wetted surface is approximated by a panel mesh and the discretization of the free surface is circumvented by using the Green function. The evaluation of the nonlinear loads is based on explicit expressions derived by the fluid-impulse theory, which can be computed efficiently. Computations are presented of the linear and nonlinear loads on the MIT/NREL tension-leg platform. Comparisons were carried out with frequency-domain linear and second-order methods. Emphasis was placed on modeling accuracy of the magnitude of nonlinear low- and high-frequency wave loads in a sea state. Although fluid-impulse theory is applied to floating wind turbines in this paper, the theory is applicable to other offshore platforms as well.
Viral communities associated with human pericardial fluids in idiopathic pericarditis.
Directory of Open Access Journals (Sweden)
Laura Fancello
Full Text Available Pericarditis is a common human disease defined by inflammation of the pericardium. Currently, 40% to 85% of pericarditis cases have no identified etiology. Most of these cases are thought to be caused by an infection of undetected, unsuspected or unknown viruses. In this work, we used a culture- and sequence-independent approach to investigate the viral DNA communities present in human pericardial fluids. Seven viral metagenomes were generated from the pericardial fluid of patients affected by pericarditis of unknown etiology and one metagenome was generated from the pericardial fluid of a sudden infant death case. As a positive control we generated one metagenome from the pericardial fluid of a patient affected by pericarditis caused by herpesvirus type 3. Furthermore, we used as negative controls a total of 6 pericardial fluids from 6 different individuals affected by pericarditis of non-infectious origin: 5 of them were sequenced as a unique pool and the remaining one was sequenced separately. The results showed a significant presence of torque teno viruses especially in one patient, while herpesviruses and papillomaviruses were present in the positive control. Co-infections by different genotypes of the same viral type (torque teno viruses or different viruses (herpesviruses and papillomaviruses were observed. Sequences related to bacteriophages infecting Staphylococcus, Enterobacteria, Streptococcus, Burkholderia and Pseudomonas were also detected in three patients. This study detected torque teno viruses and papillomaviruses, for the first time, in human pericardial fluids.
Chemical association in simple models of molecular and ionic fluids. III. The cavity function
Zhou, Yaoqi; Stell, George
1992-01-01
Exact equations which relate the cavity function to excess solvation free energies and equilibrium association constants are rederived by using a thermodynamic cycle. A zeroth-order approximation, derived previously by us as a simple interpolation scheme, is found to be very accurate if the associative bonding occurs on or near the surface of the repulsive core of the interaction potential. If the bonding radius is substantially less than the core radius, the approximation overestimates the association degree and the association constant. For binary association, the zeroth-order approximation is equivalent to the first-order thermodynamic perturbation theory (TPT) of Wertheim. For n-particle association, the combination of the zeroth-order approximation with a ``linear'' approximation (for n-particle distribution functions in terms of the two-particle function) yields the first-order TPT result. Using our exact equations to go beyond TPT, near-exact analytic results for binary hard-sphere association are obtained. Solvent effects on binary hard-sphere association and ionic association are also investigated. A new rule which generalizes Le Chatelier's principle is used to describe the three distinct forms of behaviors involving solvent effects that we find. The replacement of the dielectric-continuum solvent model by a dipolar hard-sphere model leads to improved agreement with an experimental observation. Finally, equation of state for an n-particle flexible linear-chain fluid is derived on the basis of a one-parameter approximation that interpolates between the generalized Kirkwood superposition approximation and the linear approximation. A value of the parameter that appears to be near optimal in the context of this application is obtained from comparison with computer-simulation data.
Theory of activated penetrant diffusion in viscous fluids and colloidal suspensions
Energy Technology Data Exchange (ETDEWEB)
Zhang, Rui; Schweizer, Kenneth S., E-mail: kschweiz@illinois.edu [Department of Materials Science and Frederick Seitz Materials Research Laboratory, University of Illinois, 1304 West Green Street, Urbana, Illinois 61801 (United States)
2015-10-14
We heuristically formulate a microscopic, force level, self-consistent nonlinear Langevin equation theory for activated barrier hopping and non-hydrodynamic diffusion of a hard sphere penetrant in very dense hard sphere fluid matrices. Penetrant dynamics is controlled by a rich competition between force relaxation due to penetrant self-motion and collective matrix structural (alpha) relaxation. In the absence of penetrant-matrix attraction, three activated dynamical regimes are predicted as a function of penetrant-matrix size ratio which are physically distinguished by penetrant jump distance and the nature of matrix motion required to facilitate its hopping. The penetrant diffusion constant decreases the fastest with size ratio for relatively small penetrants where the matrix effectively acts as a vibrating amorphous solid. Increasing penetrant-matrix attraction strength reduces penetrant diffusivity due to physical bonding. For size ratios approaching unity, a distinct dynamical regime emerges associated with strong slaving of penetrant hopping to matrix structural relaxation. A crossover regime at intermediate penetrant-matrix size ratio connects the two limiting behaviors for hard penetrants, but essentially disappears if there are strong attractions with the matrix. Activated penetrant diffusivity decreases strongly with matrix volume fraction in a manner that intensifies as the size ratio increases. We propose and implement a quasi-universal approach for activated diffusion of a rigid atomic/molecular penetrant in a supercooled liquid based on a mapping between the hard sphere system and thermal liquids. Calculations for specific systems agree reasonably well with experiments over a wide range of temperature, covering more than 10 orders of magnitude of variation of the penetrant diffusion constant.
Theory of activated penetrant diffusion in viscous fluids and colloidal suspensions.
Zhang, Rui; Schweizer, Kenneth S
2015-10-14
We heuristically formulate a microscopic, force level, self-consistent nonlinear Langevin equation theory for activated barrier hopping and non-hydrodynamic diffusion of a hard sphere penetrant in very dense hard sphere fluid matrices. Penetrant dynamics is controlled by a rich competition between force relaxation due to penetrant self-motion and collective matrix structural (alpha) relaxation. In the absence of penetrant-matrix attraction, three activated dynamical regimes are predicted as a function of penetrant-matrix size ratio which are physically distinguished by penetrant jump distance and the nature of matrix motion required to facilitate its hopping. The penetrant diffusion constant decreases the fastest with size ratio for relatively small penetrants where the matrix effectively acts as a vibrating amorphous solid. Increasing penetrant-matrix attraction strength reduces penetrant diffusivity due to physical bonding. For size ratios approaching unity, a distinct dynamical regime emerges associated with strong slaving of penetrant hopping to matrix structural relaxation. A crossover regime at intermediate penetrant-matrix size ratio connects the two limiting behaviors for hard penetrants, but essentially disappears if there are strong attractions with the matrix. Activated penetrant diffusivity decreases strongly with matrix volume fraction in a manner that intensifies as the size ratio increases. We propose and implement a quasi-universal approach for activated diffusion of a rigid atomic/molecular penetrant in a supercooled liquid based on a mapping between the hard sphere system and thermal liquids. Calculations for specific systems agree reasonably well with experiments over a wide range of temperature, covering more than 10 orders of magnitude of variation of the penetrant diffusion constant.
Beyond Poisson-Boltzmann: fluctuations and fluid structure in a self-consistent theory
Buyukdagli, S.; Blossey, R.
2016-09-01
Poisson-Boltzmann (PB) theory is the classic approach to soft matter electrostatics and has been applied to numerous physical chemistry and biophysics problems. Its essential limitations are in its neglect of correlation effects and fluid structure. Recently, several theoretical insights have allowed the formulation of approaches that go beyond PB theory in a systematic way. In this topical review, we provide an update on the developments achieved in the self-consistent formulations of correlation-corrected Poisson-Boltzmann theory. We introduce a corresponding system of coupled non-linear equations for both continuum electrostatics with a uniform dielectric constant, and a structured solvent—a dipolar Coulomb fluid—including non-local effects. While the approach is only approximate and also limited to corrections in the so-called weak fluctuation regime, it allows us to include physically relevant effects, as we show for a range of applications of these equations.
Dense fluid self-diffusion coefficient calculations using perturbation theory and molecular dynamics
Directory of Open Access Journals (Sweden)
COELHO L. A. F.
1999-01-01
Full Text Available A procedure to correlate self-diffusion coefficients in dense fluids by using the perturbation theory (WCA coupled with the smooth-hard-sphere theory is presented and tested against molecular simulations and experimental data. This simple algebraic expression correlates well the self-diffusion coefficients of carbon dioxide, ethane, propane, ethylene, and sulfur hexafluoride. We have also performed canonical ensemble molecular dynamics simulations by using the Hoover-Nosé thermostat and the mean-square displacement formula to compute self-diffusion coefficients for the reference WCA intermolecular potential. The good agreement obtained from both methods, when compared with experimental data, suggests that the smooth-effective-sphere theory is a useful procedure to correlate diffusivity of pure substances.
Huggins, David J
2012-11-21
The structures of biomolecules and the strengths of association between them depend critically on interactions with water molecules. Thus, understanding these interactions is a prerequisite for understanding the structure and function of all biomolecules. Inhomogeneous fluid solvation theory provides a framework to derive thermodynamic properties of individual water molecules from a statistical mechanical analysis. In this work, two biomolecules are analysed to probe the distribution and thermodynamics of surrounding water molecules. The great majority of hydration sites are predicted to contribute favourably to the total free energy with respect to bulk water, though hydration sites close to non-polar regions of the solute do not contribute significantly. Analysis of a biomolecule with a positively and negatively charged functional group predicts that a charged species perturbs the free energy of water molecules to a distance of approximately 6.0 Å. Interestingly, short simulations are found to provide converged predictions if samples are taken with sufficient frequency, a finding that has the potential to significantly reduce the required computational cost of such analysis. In addition, the predicted thermodynamic properties of hydration sites with the potential for direct hydrogen bonding interactions are found to disagree significantly for two different water models. This study provides important information on how inhomogeneous fluid solvation theory can be employed to understand the structures and intermolecular interactions of biomolecules.
One-dimensional hard rod fluid in a disordered porous medium: scaled particle theory
Directory of Open Access Journals (Sweden)
M. Holovko
2012-06-01
Full Text Available The scaled particle theory is applied to a description of thermodynamic properties of one-dimensional hard rod fluid in disordered porous media. To this end, we extended the SPT2 approach, which had been developed previously. Analytical expressions are obtained for the chemical potential and pressure of a hard-rod fluid in hard rod and overlapping hard rod matrices. A series of new approximations for SPT2 are proposed. It is shown that apart from two well known porosities such as geometrical porosity and specific probe particle porosity, a new type of porosity defined by the maximum value of packing fraction of fluid particles in porous medium should be taken into account. The grand canonical Monte-Carlo simulations are performed to verify the accuracy of the SPT2 approach in combination with the new approximations. It is observed that the theoretical description proposed in this study essentially improves the results up to the highest values of fluid densities.
Critical evidence for the prediction error theory in associative learning.
Terao, Kanta; Matsumoto, Yukihisa; Mizunami, Makoto
2015-03-10
In associative learning in mammals, it is widely accepted that the discrepancy, or error, between actual and predicted reward determines whether learning occurs. Complete evidence for the prediction error theory, however, has not been obtained in any learning systems: Prediction error theory stems from the finding of a blocking phenomenon, but blocking can also be accounted for by other theories, such as the attentional theory. We demonstrated blocking in classical conditioning in crickets and obtained evidence to reject the attentional theory. To obtain further evidence supporting the prediction error theory and rejecting alternative theories, we constructed a neural model to match the prediction error theory, by modifying our previous model of learning in crickets, and we tested a prediction from the model: the model predicts that pharmacological intervention of octopaminergic transmission during appetitive conditioning impairs learning but not formation of reward prediction itself, and it thus predicts no learning in subsequent training. We observed such an "auto-blocking", which could be accounted for by the prediction error theory but not by other competitive theories to account for blocking. This study unambiguously demonstrates validity of the prediction error theory in associative learning.
Equilibrium theory of fluids in the presence of three-body forces
Sinha, S. K.; Ram, J.; Singh, Y.
1985-10-01
Using the functional differentiation and topological reduction technique, we derive effective pair potentials to describe the correlation functions and thermodynamic properties of fluids in the presence of three-body forces. Relations between effective pair potentials derived from different properties are discussed. The pair correlation function is calculated using the Percus-Yevick integral equation theory and the hypernetted chain integral equation perturbation theory, the results are reported for neon, argon and xenon. Monte Carlo simulation is also done for Xe using the effective pair potential. The agreement found between the pair correlation function calculated from the integral equation perturbation theory and Monte Carlo simulation is good. The effect of the triple dipole and dipole-dipole-quadrupole interactions on the structure of fluid is found to be very small except near the first peak. We, however, except the sizable change in the structure factor S( q) for q < 1.0 Å -1. The effect of the three-body interactions on the thermodynamic properties like internal energy and pressure is always measurable.
Simulating Cerebrospinal Fluid Flow and Spinal Cord Movement Associated with Syringomyelia
Vinje, Vegard
2016-01-01
Syringomyelia is a progressive disease where fluid filled cavities develop inside the spinal cord, and is frequently seen together with Chiari Malformation I (CMI). CMI is characterized by downwards displacements of the Cerebellar Tonsils obstructing flow in the Subarachnoid space, (SAS) which causes abnormal Cerebrospinal fluid (CSF) flow. Many theories on the pathogenesis of syringomyelia have been proposed, many related to abnormal CSF flow, but a full explanation has not yet been given. I...
Mechanical design problems associated with turbopump fluid film bearings
Evces, Charles R.
1990-01-01
Most high speed cryogenic turbopumps for liquid propulsion rocket engines currently use ball or roller contact bearings for rotor support. The operating speeds, loads, clearances, and environments of these pumps combine to make bearing wear a limiting factor on turbopump life. An example is the high pressure oxygen turbopump (HPOTP) used in the Space Shuttle Main Engine (SSME). Although the HPOTP design life is 27,000 seconds at 30,000 rpms, or approximately 50 missions, bearings must currently be replaced after 2 missions. One solution to the bearing wear problem in the HPOTP, as well as in future turbopump designs, is the utilization of fluid film bearings in lieu of continuous contact bearings. Hydrostatic, hydrodynamic, and damping seal bearings are all replacement candidates for contact bearings in rocket engine high speed turbomachinery. These three types of fluid film bearings have different operating characteristics, but they share a common set of mechanical design opportunities and difficulties. Results of research to define some of the mechanical design issues are given. Problems considered include transient strat/stop rub, non-operational rotor support, bearing wear inspection and measurement, and bearing fluid supply route. Emphasis is given to the HPOTP preburner pump (PBP) bearing, but the results are pertinent to high-speed cryogenic turbomachinery in general.
Association between fluid balance and mortality in patients with septic shock
DEFF Research Database (Denmark)
Cronhjort, M; Hjortrup, P B; Holst, L B;
2016-01-01
restrictive use of intravenous fluids, however, is uncertain. We therefore aimed to investigate the association between a cumulative fluid balance 3 days after randomization and 90-day mortality in a recent Nordic multicentre cohort of patients with septic shock. METHODS: A post hoc analysis of patients from...
Relativistic transport theory for simple fluids at first order in the gradients: a stable picture
Sandoval-Villalbazo, A; García-Colin, L S
2008-01-01
In this paper we show how using a relativistic kinetic equation. The ensuing expression for the heat flux can be casted in the form required by Classical Irreversible Thermodynamics. Indeed, it is linearly related to the temperature and number density gradients and not to the acceleration as the so called first order in the gradients theories contend. Since the specific expressions for the transport coefficients are irrelevant for our purposes, the BGK form of the kinetic equation is used. Moreover, from the resulting hydrodynamic equations it is readily seen that no instabilities are present in the transverse hydrodynamic velocity mode of the simple relativistic fluid.
Droplet evaporation in one-component fluids: Dynamic van der Waals theory
Teshigawara, Ryohei; Onuki, Akira
2008-01-01
In a one-component fluid, we investigate evaporation of a small axysymmetric liquid droplet in the partial wetting condition on a heated wall at $T\\sim 0.9 T_c$. In the dynamic van der Waals theory (Phys. Rev. E {\\bf 75}, 036304 (2007)), we take into account the latent heat transport from liquid to gas upon evaporation. Along the gas-liquid interface, the temperature is nearly equal to the equilibrium coexisting temperature away from the substrate, but it rises sharply to the wall temperature...
Generalized extended Navier-Stokes theory: Multiscale spin relaxation in molecular fluids
DEFF Research Database (Denmark)
Hansen, Jesper Schmidt
2013-01-01
This paper studies the relaxation of the molecular spin angular velocity in the framework of generalized extended Navier-Stokes theory. Using molecular dynamics simulations, it is shown that for uncharged diatomic molecules the relaxation time decreases with increasing molecular moment of inertia...... per unit mass. In the regime of large moment of inertia the fast relaxation is wave-vector independent and dominated by the coupling between spin and the fluid streaming velocity, whereas for small inertia the relaxation is slow and spin diffusion plays a significant role. The fast wave...
Cantorian Fractal Space-Time Fluctuations in Turbulent Fluid Flows and the Kinetic Theory of Gases
Selvam, A M
1999-01-01
Fluid flows such as gases or liquids exhibit space-time fluctuations on all scales extending down to molecular scales. Such broadband continuum fluctuations characterise all dynamical systems in nature and are identified as selfsimilar fractals in the newly emerging multidisciplinary science of nonlinear dynamics and chaos. A cell dynamical system model has been developed by the author to quantify the fractal space-time fluctuations of atmospheric flows. The earth's atmosphere consists of a mixture of gases and obeys the gas laws as formulated in the kinetic theory of gases developed on probabilistic assumptions in 1859 by the physicist James Clerk Maxwell. An alternative theory using the concept of fractals and chaos is applied in this paper to derive these fundamental gas laws.
Sundararaman, Ravishankar
2014-01-01
Classical density-functional theory provides an efficient alternative to molecular dynamics simulations for understanding the equilibrium properties of inhomogeneous fluids. However, application of density-functional theory to multi-site molecular fluids has so far been limited by complications due to the implicit molecular geometry constraints on the site densities, whose resolution typically requires expensive Monte Carlo methods. Here, we present a general scheme of circumventing this so-called inversion problem: compressed representations of the orientation density. This approach allows us to combine the superior iterative convergence properties of multipole representations of the fluid configuration with the improved accuracy of site-density functionals. Next, from a computational perspective, we show how to extend the DFT++ algebraic formulation of electronic density-functional theory to the classical fluid case and present a basis-independent discretization of our formulation for molecular classical de...
Jao, C.-S.; Hau, L.-N.
2016-11-01
Electrostatic streaming instabilities have been proposed as the generation mechanism for the electrostatic solitary waves observed in various space plasma environments. Past studies on the subject have been mostly based on the kinetic theory and particle simulations. In this paper, we extend our recent study based on one-dimensional fluid theory and particle simulations to two-dimensional regimes for both bi-streaming and bump-on-tail streaming instabilities in electron-ion plasmas. Both linear fluid theory and kinetic simulations show that for bi-streaming instability, the oblique unstable modes tend to be suppressed by the increasing background magnetic field, while for bump-on-tail instability, the growth rates of unstable oblique modes are increased with increasing background magnetic field. For both instabilities, the fluid theory gives rise to the linear growth rates and the wavelengths of unstable modes in good agreement with those obtained from the kinetic simulations. For unmagnetized and weakly magnetized systems, the formed electrostatic structures tend to diminish after the long evolution, while for relatively stronger magnetic field cases, the solitary waves may merge and evolve to steady one-dimensional structures. Comparisons between one and two-dimensional results are made and the effects of the ion-to-electron mass ratio are also examined based on the fluid theory and kinetic simulations. The study concludes that the fluid theory plays crucial seeding roles in the kinetic evolution of electrostatic streaming instabilities.
Quasi-chemical Theory for the Statistical Thermodynamics of the Hard Sphere Fluid
Pratt, L R; Gómez, M A; Gentile, M E; Pratt, Lawrence R.; Violette, Randall A. La; Gomez, Maria A.; Gentile, Mary E.
2001-01-01
We develop a quasi-chemical theory for the study of packing thermodynamics in dense liquids. The situation of hard-core interactions is addressed by considering the binding of solvent molecules to a precisely defined `cavity' in order to assess the probability that the `cavity' is entirely evacuated. The primitive quasi-chemical approximation corresponds to a extension of the Poisson distribution used as a default model in an information theory approach. This primitive quasi-chemical theory is in good qualitative agreement with the observations for the hard sphere fluid of occupancy distributions that are central to quasi-chemical theories but begins to be quantitatively erroneous for the equation of state in the dense liquid regime of $\\rho d^3>$0.6. How the quasi-chemical approach can be iterated to treat correlation effects is addressed. Consideration of neglected correlation effects leads to a simple model for the form of those contributions neglected by the primitive quasi-chemical approximation. These c...
13th Conference of the Canadian Number Theory Association
Alaca, Şaban; Williams, Kenneth
2015-01-01
The theory of numbers continues to occupy a central place in modern mathematics because of both its long history over many centuries as well as its many diverse applications to other fields such as discrete mathematics, cryptography, and coding theory. The proof by Andrew Wiles (with Richard Taylor) of Fermat’s last theorem published in 1995 illustrates the high level of difficulty of problems encountered in number-theoretic research as well as the usefulness of the new ideas arising from its proof. The thirteenth conference of the Canadian Number Theory Association was held at Carleton University, Ottawa, Ontario, Canada from June 16 to 20, 2014. Ninety-nine talks were presented at the conference on the theme of advances in the theory of numbers. Topics of the talks reflected the diversity of current trends and activities in modern number theory. These topics included modular forms, hypergeometric functions, elliptic curves, distribution of prime numbers, diophantine equations, L-functions, Diophantine app...
Dynamic self-consistent field theory of inhomogeneous complex fluids under shear
Mihajlovic, Maja Lazar
Understanding and predicting the interplay between morphology and rheology of sheared, inhomogeneous, complex fluids is of great importance. Yet the modeling of such phenomena is in its infancy. We have developed a novel dynamic self-consistent field (DSCF) theory that makes possible a detailed computational study of such phenomena. Our DSCF theory couples the time evolution of chain conformation statistics with probabilistic transport equations for volume fractions and momenta, based on local conservation laws formulated on a segmental scale. To generate chain conformation statistics, we are using a modification of the lattice random walk formalism of Scheutjens and Fleer. Their static SCF theory is limited to equilibrium systems, since probability distributions are obtained by free energy minimization, assuming isotropic Gaussian chain conformations. In contrast, our DSCF approach accounts for explicit time evolution of the segmental and (anisotropic) conditional stepping probabilities used for generating chain conformations. We have applied the DSCF model to a variety of isothermal inhomogenous fluids containing homopolymers, block copolymers and colloidal particles. In all the simulations, the system is equilibrated before the onset of a steady shear at the walls. Our results suggest that, on short time scales, the velocity evolution resembles shock wave propagation. In the course of time, the amplitude of the shock waves is viscously damped, giving rise to a Couette-like steady state velocity profile. This is also reflected in the temporal evolution of the tensor of the second moment of the end-to-end vector and the dissipative stress tensor. The two- and three-component polymer blends (with a diblock copolymer as the third component) exhibit the interfacial velocity and viscosity slip. The addition of a diblock copolymer suppresses the velocity, and therefore the viscosity slip. Colloidal particles suspended in a simple fluid exhibit layering near the walls
Non-associative deformations of geometry in double field theory
Energy Technology Data Exchange (ETDEWEB)
Blumenhagen, Ralph; Fuchs, Michael [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut),Föhringer Ring 6, 80805 München (Germany); Haßler, Falk [Arnold Sommerfeld Center for Theoretical Physics,LMU, Theresienstr. 37, 80333 München (Germany); Lüst, Dieter [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut),Föhringer Ring 6, 80805 München (Germany); Arnold Sommerfeld Center for Theoretical Physics,LMU, Theresienstr. 37, 80333 München (Germany); Sun, Rui [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut),Föhringer Ring 6, 80805 München (Germany)
2014-04-23
Non-geometric string backgrounds were proposed to be related to a non-associative deformation of the space-time geometry. In the flux formulation of double field theory (DFT), the structure of mathematically possible non-associative deformations is analyzed in detail. It is argued that on-shell there should not be any violation of associativity in the effective DFT action. For imposing either the strong or the weaker closure constraint we discuss two possible non-associative deformations of DFT featuring two different ways how on-shell associativity can still be kept.
Indian Academy of Sciences (India)
Amita Wadehra; B M Deb
2007-09-01
A time-dependent generalized non-linear Schrödinger equation (GNLSE) of motion was earlier derived in our laboratory by combining density functional theory and quantum fluid dynamics in threedimensional space. In continuation of the work reported previously, the GNLSE is applied to provide additional knowledge on the femtosecond dynamics of the electron density in the hydrogen molecule interacting with high-intensity laser fields. For this purpose, the GNLSE is solved numerically for many time-steps over a total interaction time of 100 fs, by employing a finite-difference scheme. Various time-dependent (TD) quantities, namely, electron density, ground-state survival probability and dipole moment have been obtained for two laser wavelengths and four different intensities. The high-order harmonics generation (HHG) is also examined. The present approach goes beyond the linear response formalism and, in principle, calculates the TD electron density to all orders of change.
Beatification: Flattening the Poisson Bracket for Two-Dimensional Fluid and Plasma Theories
Viscondi, Thiago F; Morrison, Philip J
2016-01-01
A perturbative method called beatification is presented for a class of two-dimensional fluid and plasma theories. The Hamiltonian systems considered, namely the Euler, Vlasov-Poisson, Hasegawa-Mima, and modified Hasegawa-Mima equations, are naturally described in terms of noncanonical variables. The beatification procedure amounts to finding the correct transformation that removes the explicit variable dependence from a noncanonical Poisson bracket and replaces it with a fixed dependence on a chosen state in phase space. As such, beatification is a major step toward casting the Hamiltonian system in its canonical form, thus enabling or facilitating the use of analytical and numerical techniques that require or favor a representation in terms of canonical, or beatified, Hamiltonian variables.
Transmission Characteristics in Tubular Acoustic Metamaterials Studied with Fluid Impedance Theory
Institute of Scientific and Technical Information of China (English)
FAN Li; ZHANG Shu-Yi; ZHANG Hui
2011-01-01
Tubular acoustic metamaterials with negative densities composed of periodical membranes set up along pipes are studied with the fluid impedance theory. In addition to the conventional forbidden bands induced by the Bragg-scattering due to the periodic distributions of different acoustic impedances, the low-frequency forbidden band (LFB) with the low-frequency limit of zero Hertz is studied, in which the LFB is explained with acoustic impedance matching and the Bloch theory. Furthermore, the influences of the structural parameters of the tubular acoustic metamaterials on the transmission characteristics, such as the transmission coefficients, dispersion curves, widths of forbidden and pass bands, fluctuations in pass bands, etc., are evaluated, which can be used in the optimization of the acoustic insulation ability of the metamaterials.%Tubular acoustic metamaterials with negative densities composed of periodical membranes set up along pipes are studied with the fluid impedance theory.In addition to the conventional forbidden bands induced by the Bragg-scattering due to the periodic distributions of different acoustic impedances,the low-frequency forbidden band (LFB) with the low-frequency limit of zero Hertz is studied,in which the LFB is explained with acoustic impedance matching and the Bloch theory.Furthermore,the influences of the structural parameters of the tubular acoustic metamaterials on the transmission characteristics,such as the transmission coefficients,dispersion curves,widths of forbidden and pass bands,fluctuations in pass bands,etc.,are evaluated,which can be used in the optimization of the acoustic insulation ability of the metamaterials.Like electromagnetic metamaterials,acoustic metamaterials have been presented with different structures,which have negative constitutive parameters of acoustic propagation and can realize unique acoustic characteristics and applications.[1-5] Recently,acoustic metamaterials were introduced into acoustic resonance
Institute of Scientific and Technical Information of China (English)
Liu Jian-jun
2003-01-01
During the development of low permeability reservoirs. the interaction between fluid flow and rock-mass deformation is obvious. On the basis of fluid mechanics in porous media and elasto-plastic theory. the author presents an equivalent continuum model to simulate fluid flow in fractured low-permeability oil reservoir coupled with geo-stress. The model not only reflects the porosity change of matrix, but also the permeability change due to the opening and closing of fracture. By analyzing of simulation results, the changes in porosity and permeability and their effect on oil development are studied.
Fakhrabadi, Mir Masoud Seyyed; Rastgoo, Abbas; Ahmadian, Mohammad Taghi
2013-01-01
The paper presents the effects of fluid flow on the static and dynamic properties of carbon nanotubes that convey a viscous fluid. The mathematical model is based on the modified couple stress theory. The effects of various fluid parameters and boundary conditions on the pull-in voltages are investigated in detail. The applicability of the proposed system as nanovalves or nanosensors in nanoscale fluidic systems is elaborated. The results confirm that the nanoscale system studied in this paper can be properly applied for these purposes.
Jans, J.; Bruggemann, R.J.M.; Christmann, V.; Verweij, P.E.; Warris, A.
2013-01-01
Invasive Candida infections associated with medical devices are very difficult to cure without device removal. We present a case of neonatal cerebrospinal fluid shunt-associated Candida meningitis, in which removal of the device was precluded, that was successfully treated with caspofungin. Pharmaco
Duran-Olivencia, Miguel A.; Goddard, Ben; Kalliadasis, Serafim
2015-11-01
Over the last few decades the classical density-functional theory (DFT) and its dynamic extensions (DDFTs) have become a remarkably powerful tool in the study of colloidal fluids. Recently there has been extensive research to generalise all previous DDFTs finally yielding a general DDFT equation (for spherical particles) which takes into account both inertia and hydrodynamic interactions (HI) which strongly influence non-equilibrium properties. The present work will be devoted to a further generalisation of such a framework to systems of anisotropic particles. To this end, the kinetic equation for the Brownian particle distribution function is derived starting from the Liouville equation and making use of Zwanzig's projection-operator techniques. By averaging over all but one particle, a DDFT equation is finally obtained with some similarities to that for spherical colloids. However, there is now an inevitable translational-rotational coupling which affects the diffusivity of asymmetric particles. Lastly, in the overdamped (high friction) limit the theory is notably simplified leading to a DDFT equation which agrees with previous derivations. We acknowledge financial support from European Research Council via Advanced Grant No. 247031.
Kinematics of fluid particles on the sea surface. Part 1. Hamiltonian theory
Fedele, Francesco; Farazmand, Mohammad
2015-01-01
We derive the John-Sclavounos equations describing the motion of a fluid particle on the sea surface from first principles using Lagrangian and Hamiltonian formalisms applied to the motion of a frictionless particle constrained on an unsteady surface. The main result is that vorticity generated on a stress-free surface vanishes at a wave crest when the horizontal particle velocity equals the crest propagation speed, which is the kinematic criterion for wave breaking. If this holds for the largest crest, then the symplectic two-form associated with the Hamiltonian dynamics reduces instantaneously to that associated with the motion of a particle in free flight, as if the surface did not exist. Further, exploiting the conservation of the Hamiltonian function for steady surfaces and traveling waves we show that particle velocities remain bounded at all times, ruling out the possibility of the finite-time blowup of solutions.
Bonilla, Mauricio R; Bhatia, Suresh K
2012-01-10
Molecular transport in nanoconfined spaces plays a key role in many emerging technologies for gas separation and storage, as well as in nanofluidics. The infiltration of fluid mixtures into the voids of porous frameworks having complex topologies is common place to these technologies, and optimizing their performance entails developing a deeper understanding of how the flow of these mixtures is affected by the morphology of the pore space, particularly its pore size distribution and pore connectivity. Although several techniques have been developed for the estimation of the effective diffusivity characterizing the transport of single fluids through porous materials, this is not the case for fluid mixtures, where the only alternatives rely on a time-consuming solution of the pore network equations or adaptations of the single fluid theories which are useful for a limited type of systems. In this paper, a hybrid multicomponent effective medium-correlated random walk theory for the calculation of the effective transport coefficients matrix of fluid mixtures diffusing through porous materials is developed. The theory is suitable for those systems in which component fluxes at the single pore level can be related to the potential gradients of the different species through linear flux laws and corresponds to a generalization of the classical single fluid effective medium theory for the analysis of random resistor networks. Comparison with simulation of the diffusion of binary CO(2)/H(2)S and ternary CO(2)/H(2)S/C(3)H(8) gas mixtures in membranes modeled as large networks of randomly oriented pores with both continuous and discrete pore size distributions demonstrates the power of the theory, which was tested using the well-known generalized Maxwell-Stefan model for surface diffusion at the single pore level.
Thermodynamically self-consistent theories of fluids interacting through short-range forces.
Caccamo, C; Pellicane, G; Costa, D; Pini, D; Stell, G
1999-11-01
The self-consistent Ornstein-Zernike approximation (SCOZA), the generalized mean spherical approximation (GMSA), the modified hypernetted chain (MHNC) approximation, and the hierarchical reference theory (HRT) are applied to the determination of thermodynamic and structural properties, and the phase diagram of the hard-core Yukawa fluid (HCYF). We investigate different Yukawa-tail screening lengths lambda, ranging from lambda=1.8 (a value appropriate to approximate the shape of the Lennard-Jones potential) to lambda=9 (suitable for a simple one-body modelization of complex fluids like colloidal suspensions and globular protein solutions). The comparison of the results obtained with computer simulation data shows that at relatively low lambda's all the theories are fairly accurate in the prediction of thermodynamic and structural properties; as far as the phase diagram is concerned, the SCOZA and HRT are able to predict the binodal line and the critical parameters in a quantitative manner. At lambda=4 some discrepancies begin to emerge in the performances of the different theoretical approaches: the MHNC remains, on the whole, reasonably accurate in predicting the energy and the contact value of the radial distribution function; the SCOZA predicts well the equation of state up to the highest lambda values investigated. The GMSA and the MHNC underestimate and overestimate, respectively, the liquid coexisting density, while the SCOZA and HRT yield liquid branches that fall between the two former theoretical predictions, although both appear to overestimate the critical temperature somewhat. At higher lambda's the GMSA and MHNC binodals further worsen, while the SCOZA appears to remain usefully predictive. In general, the predictions of all the theories tend to slightly worsen at low temperatures and high density. The determination of the freezing line, performed by means of a one-phase "freezing criterion" (due to other authors) is not particularly satisfactory within
DEFF Research Database (Denmark)
Kohan, Donald E; Lambers Heerspink, Hiddo J; Coll, Blai
2015-01-01
. CONCLUSIONS: In the Reducing Residual Albuminuria in Subjects With Diabetes and Nephropathy With Atrasentan/JAPAN trials, atrasentan-associated fluid retention was more likely in patients with diabetes and nephropathy who had lower eGFR or received a higher dose of atrasentan. Finding that albuminuria......BACKGROUND AND OBJECTIVES: Endothelin A receptor antagonists (ERAs) decrease residual albuminuria in patients with diabetic kidney disease; however, their clinical utility may be limited by fluid retention. Consequently, the primary objective of this study was to identify predictors for ERA......-induced fluid retention among patients with type 2 diabetes and CKD. A secondary objective was to determine if the degree of fluid retention necessarily correlated with the magnitude of albuminuria reduction in those patients receiving ERAs. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A post hoc analysis...
Kalyuzhnyi, Y V; Marshall, B D; Chapman, W G; Cummings, P T
2013-07-28
We propose a second-order version of the resummed thermodynamic perturbation theory for patchy colloidal models with arbitrary number of multiply bondable patches. The model is represented by the hard-sphere fluid system with several attractive patches on the surface and resummation is carried out to account for blocking effects, i.e., when the bonding of a particle restricts (blocks) its ability to bond with other particles. The theory represents an extension of the earlier proposed first order resummed thermodynamic perturbation theory for central force associating potential and takes into account formation of the rings of the particles. In the limiting case of singly bondable patches (total blockage), the theory reduces to Wertheim thermodynamic perturbation theory for associating fluids. Closed-form expressions for the Helmholtz free energy, pressure, internal energy, and chemical potential of the model with an arbitrary number of equivalent doubly bondable patches are derived. Predictions of the theory for the model with two patches appears to be in a very good agreement with predictions of new NVT and NPT Monte Carlo simulations, including the region of strong association.
Energy Technology Data Exchange (ETDEWEB)
Sorensen, C.M.
1976-01-01
An effort to expand light-scattering autocorrelation techniques to Brownian diffusional and critical fluid systems in which multiple scattering effects are important, and to understand the observed similarity of the Rayleigh linewidth of light scattered from these two seemingly different systems is discussed. A formalism was developed to find the light field multiply scattered from a suspension of Brownian diffusing particles. For the field doubly scattered from a system of noninteracting Brownian particles, the intensity and correlation time were much less dependent on the scattering angle than for the singly scattered component. The polarized and depolarized correlation times of light scattered from Brownian particle systems were measured. The double-scattering formalism was extended to light scattered from critical fluid systems. In the region k xi greater than 5 the doubly and singly scattered correlation times were nearly equal. The dynamic droplet model of critical phenomena was developed which gives the proper, experimentally verified, forms for the intensity and linewidth of light scattered from a critical fluid. To test the dynamic droplet model and the mode theories Rayleigh linewidth predictions, light-scattering measurements were performed on the critical fluid system methanol and cyclohexane. The data agreed with both the dynamic droplet and decoupled mode theory predictions. The depolarized scattered spectra from a critical fluid were measured, and qualitative agreement with the double-scattering theory was found. 57 figures, 5 tables.
Dufal, Simon; Lafitte, Thomas; Haslam, Andrew J.; Galindo, Amparo; Clark, Gary N. I.; Vega, Carlos; Jackson, George
2015-05-01
An accurate representation of molecular association is a vital ingredient of advanced equations of state (EOSs), providing a description of thermodynamic properties of complex fluids where hydrogen bonding plays an important role. The combination of the first-order thermodynamic perturbation theory (TPT1) of Wertheim for associating systems with an accurate description of the structural and thermodynamic properties of the monomer fluid forms the basis of the statistical associating fluid theory (SAFT) family of EOSs. The contribution of association to the free energy in SAFT and related EOSs is very sensitive to the nature of intermolecular potential used to describe the monomers and, crucially, to the accuracy of the representation of the thermodynamic and structural properties. Here we develop an accurate description of the association contribution for use within the recently developed SAFT-VR Mie framework for chain molecules formed from segments interacting through a Mie potential [T. Lafitte, A. Apostolakou, C. Avendaño, A, Galindo, C. S. Adjiman, E. A. Müller, and G. Jackson, J. Chem. Phys. 139, 154504 (2013)]. As the Mie interaction represents a soft-core potential model, a method similar to that adopted for the Lennard-Jones potential [E. A. Müller and K. E. Gubbins, Ind. Eng. Chem. Res. 34, 3662 (1995)] is employed to describe the association contribution to the Helmholtz free energy. The radial distribution function (RDF) of the Mie fluid (which is required for the evaluation of the integral at the heart of the association term) is determined for a broad range of thermodynamic conditions (temperatures and densities) using the reference hyper-netted chain (RHNC) integral-equation theory. The numerical data for the association kernel of Mie fluids with different association geometries are then correlated for a range of thermodynamic states to obtain a general expression for the association contribution which can be applied for varying values of the Mie
Theory of two-dimensional Fourier transform electron spin resonance for ordered and viscous fluids
Lee, Sanghyuk; Budil, David E.; Freed, Jack H.
1994-10-01
A comprehensive theory for interpreting two-dimensional Fourier transform (2D-FT) electron spin resonance (ESR) experiments that is based on the stochastic Liouville equation is presented. It encompasses the full range of motional rates from fast through very slow motions, and it also provides for microscopic as well as macroscopic molecular ordering. In these respects it is as sophisticated in its treatment of molecular dynamics as the theory currently employed for analyzing cw ESR spectra. The general properties of the pulse propagator superoperator, which describes the microwave pulses in Liouville space, are analyzed in terms of the coherence transfer pathways appropriate for COSY (correlation spectroscopy), SECSY (spin-echo correlation spectroscopy), and 2D-ELDOR (electron-electron double resonance) sequences wherein either the free-induction decay (FID) or echo decay is sampled. Important distinctions are made among the sources of inhomogeneous broadening, which include (a) incomplete spectral averaging in the slow-motional regime, (b) unresolved superhyperfine structure and related sources, and (c) microscopic molecular ordering but macroscopic disorder (MOMD). The differing effects these sources of inhomogeneous broadening have on the two mirror image coherence pathways observed in the dual quadrature 2D experiments, as well as on the auto vs crosspeaks of 2D-ELDOR, is described. The theory is applied to simulate experiments of nitroxide spin labels in complex fluids such as membrane vesicles, where the MOMD model applies and these distinctions are particularly relevant, in order to extract dynamic and ordering parameters. The recovery of homogeneous linewidths from FID-based COSY experiments on complex fluids with significant inhomogeneous broadening is also described. The theory is applied to the ultraslow motional regime, and a simple method is developed to determine rotational rates from the broadening of the autopeaks of the 2D-ELDOR spectra as a
Klimachkov, D. A.; Petrosyan, A. S.
2016-09-01
Shallow water magnetohydrodynamic (MHD) theory describing incompressible flows of plasma is generalized to the case of compressible flows. A system of MHD equations is obtained that describes the flow of a thin layer of compressible rotating plasma in a gravitational field in the shallow water approximation. The system of quasilinear hyperbolic equations obtained admits a complete simple wave analysis and a solution to the initial discontinuity decay problem in the simplest version of nonrotating flows. In the new equations, sound waves are filtered out, and the dependence of density on pressure on large scales is taken into account that describes static compressibility phenomena. In the equations obtained, the mass conservation law is formulated for a variable that nontrivially depends on the shape of the lower boundary, the characteristic vertical scale of the flow, and the scale of heights at which the variation of density becomes significant. A simple wave theory is developed for the system of equations obtained. All self-similar discontinuous solutions and all continuous centered self-similar solutions of the system are obtained. The initial discontinuity decay problem is solved explicitly for compressible MHD equations in the shallow water approximation. It is shown that there exist five different configurations that provide a solution to the initial discontinuity decay problem. For each configuration, conditions are found that are necessary and sufficient for its implementation. Differences between incompressible and compressible cases are analyzed. In spite of the formal similarity between the solutions in the classical case of MHD flows of an incompressible and compressible fluids, the nonlinear dynamics described by the solutions are essentially different due to the difference in the expressions for the squared propagation velocity of weak perturbations. In addition, the solutions obtained describe new physical phenomena related to the dependence of the
Renormalized kinetic theory of classical fluids in and out of equilibrium
Daligault, Jerome
2011-01-01
We present a theory for the construction of renormalized kinetic equations to describe the dynamics of classical systems of particles in or out of equilibrium. A closed, self-consistent set of evolution equations is derived for the single-particle phase-space distribution function $f$, the correlation function $C=$, the retarded and advanced density response functions $\\chi^{R,A}=\\delta f/\\delta\\phi$ to an external potential $\\phi$, and the associated memory functions $\\Sigma^{R,A,C}$. The basis of the theory is an effective action functional $\\Omega$ of external potentials $\\phi$ that contains all information about the dynamical properties of the system. In particular, its functional derivatives generate successively the single-particle phase-space density $f$ and all the correlation and density response functions, which are coupled through an infinite hierarchy of evolution equations. Traditional renormalization techniques are then used to perform the closure of the hierarchy through memory functions. The l...
Diagrammatic analysis of correlations in polymer fluids: Cluster diagrams via Edwards’ field theory
Morse, David C.
2006-10-01
Edwards' functional integral approach to the statistical mechanics of polymer liquids is amenable to a diagrammatic analysis in which free energies and correlation functions are expanded as infinite sums of Feynman diagrams. This analysis is shown to lead naturally to a perturbative cluster expansion that is closely related to the Mayer cluster expansion developed for molecular liquids by Chandler and co-workers. Expansion of the functional integral representation of the grand-canonical partition function yields a perturbation theory in which all quantities of interest are expressed as functionals of a monomer-monomer pair potential, as functionals of intramolecular correlation functions of non-interacting molecules, and as functions of molecular activities. In different variants of the theory, the pair potential may be either a bare or a screened potential. A series of topological reductions yields a renormalized diagrammatic expansion in which collective correlation functions are instead expressed diagrammatically as functionals of the true single-molecule correlation functions in the interacting fluid, and as functions of molecular number density. Similar renormalized expansions are also obtained for a collective Ornstein-Zernicke direct correlation function, and for intramolecular correlation functions. A concise discussion is given of the corresponding Mayer cluster expansion, and of the relationship between the Mayer and perturbative cluster expansions for liquids of flexible molecules. The application of the perturbative cluster expansion to coarse-grained models of dense multi-component polymer liquids is discussed, and a justification is given for the use of a loop expansion. As an example, the formalism is used to derive a new expression for the wave-number dependent direct correlation function and recover known expressions for the intramolecular two-point correlation function to first-order in a renormalized loop expansion for coarse-grained models of
Characterization of Phase Transition in Heisenberg Fluids from Density Functional Theory
Institute of Scientific and Technical Information of China (English)
LI Liang-Sheng; LI Li; CHEN Xiao-Song
2009-01-01
The phase transition of Heisenberg fluid has been investigated with the density functional theory in mean-field approximation (MF).The matrix of the second derivatives of the grand canonical potential Ω with respect to the particle density fluctuations and the magnetization fluctuations has been investigated and diagonalized.The smallest eigenvalue being 0 signalizes the phase instability and the related eigenvector characterizes this phase transition.We find a Curie line where the order parameter is pure magnetization and a spinodM where the order parameter is a mixture of particle density and magnetization.Along the spinodal, the character of phase instability changes continuously from predominant condensation to predominant ferromagnetic phase transition with the decrease of total density.The spinodal meets the Curie line at the critical endpoint with the reduced density ρ*= ρσ3=0.224 and the reduced temperature T* = kT/ε = 1.87 (σ is the diameter of Heisenberg hard sphere and e is the coupling constant).
Numerical simulation on fault water-inrush based on fluid-solid coupling theory
Institute of Scientific and Technical Information of China (English)
HUANG Han-fu; MAO Xian-biao; YAO Bang-hua; PU Hai
2012-01-01
About 75％ water-inrush accidents in China are caused by geological structure such as faults,therefore,it is necessary to investigate the water-inrush mechanism of faults to provide references for the mining activity above confined water.In this paper,based on the fluid-solid coupling theory,we built the stress-seepage coupling model for rock,then we combined with an example of water-inrush caused by fault,studied the water-inrush mechanism by using the numerical software COMSOL Mutiphysics,analyzed the change rule of shear stress,vertical stress,plastic area and water pressure for stope with a fault,and estimated the water-inrush risk at the different distances between working faces and the fault.The numerical simulation results indicate that:(1) the water-inrush risk will grow as the decrease of the distance between working face and the fault;(2) the failure mode of the rock in floor with fault is shear failure; (3) the rock between water-containing fault and working face failure is the reason for water-inrush.
Characterization of Phase Transition in Heisenberg Fluids from Density Functional Theory
Li, Liang-Sheng; Li, Li; Chen, Xiao-Song
2009-02-01
The phase transition of Heisenberg fluid has been investigated with the density functional theory in mean-field approximation (MF). The matrix of the second derivatives of the grand canonical potential Ω with respect to the particle density fluctuations and the magnetization fluctuations has been investigated and diagonalized. The smallest eigenvalue being 0 signalizes the phase instability and the related eigenvector characterizes this phase transition. We find a Curie line where the order parameter is pure magnetization and a spinodal where the order parameter is a mixture of particle density and magnetization. Along the spinodal, the character of phase instability changes continuously from predominant condensation to predominant ferromagnetic phase transition with the decrease of total density. The spinodal meets the Curie line at the critical endpoint with the reduced density ρ* = ρσ3 = 0.224 and the reduced temperature T* = kT/in = 1.87 (σ is the diameter of Heisenberg hard sphere and in is the coupling constant).
Selection principles and pattern formation in fluid mechanics and nonlinear shell theory
Sather, Duane P.
1987-01-01
Research accomplishments are summarized and publications generated under the contract are listed. The general purpose of the research was to investigate various symmetry breaking problems in fluid mechanics by the use of structure parameters and selection principles. Although all of the nonlinear problems studied involved systems of partial differential equations, many of these problems led to the study of a single nonlinear operator equation of the form F(w, lambda, gamma) = 0, (w is an element of H), (lambda is an element of R1), (gamma is an element of R1). Instead of varying only the load parameter lambda, as is often done in the study of such equations, one of the main ideas used was to vary the structure parameter gamma in such a way that stable solutions were obtained. In this way one determines detailed stability results by making use of the structure of the model equations and the known physical parameters of the problem. The approach was carried out successfully for Benard-type convection problems, Taylor-like problems for short cylinders, rotating Couette-Poiseuille channel flows, and plane Couette flows. The main focus of the research was on wave theory of vortex breakdown in a tube. A number of preliminary results for inviscid axisymmetric flows were obtained.
Zeighampour, Hamid; Tadi Beni, Y.
2014-07-01
This work investigated vibrations and instability of double-walled carbon nanotube (DWCNT) conveying fluid by a modified couple stress theory. For this purpose, Donnell's shell model was developed and, using the modified couple stress theory, the equations of motion and corresponding classical and non-classical boundary conditions of DWCNT were obtained through Hamilton's principle. Then, DWCNT with simple-simple and clamped-clamped supports were investigated. The effect of the van der Waals (vdW) forces was considered between the two walls, and the DWCNT surroundings were modeled as a visco-Pasternak foundation. The governing equations of motion and corresponding boundary conditions were discretized through differential quadrature method (DQM), and the vibration problem was solved by using the boundary conditions. The results show that the effects of fluid velocity, stiffness and damping of the visco-Pasternak foundation, nanotube length, and size parameter in the modified couple stress theory are stronger than in the classical theory. Finally, the effect of vdW forces and presence of fluid in the DWCNT examined on the natural frequencies of DWCNT.
Theory of the vortex-clustering transition in a confined two-dimensional quantum fluid
Yu, Xiaoquan; Billam, Thomas P.; Nian, Jun; Reeves, Matthew T.; Bradley, Ashton S.
2016-08-01
Clustering of like-sign vortices in a planar bounded domain is known to occur at negative temperature, a phenomenon that Onsager demonstrated to be a consequence of bounded phase space. In a confined superfluid, quantized vortices can support such an ordered phase, provided they evolve as an almost isolated subsystem containing sufficient energy. A detailed theoretical understanding of the statistical mechanics of such states thus requires a microcanonical approach. Here we develop an analytical theory of the vortex clustering transition in a neutral system of quantum vortices confined to a two-dimensional disk geometry, within the microcanonical ensemble. The choice of ensemble is essential for identifying the correct thermodynamic limit of the system, enabling a rigorous description of clustering in the language of critical phenomena. As the system energy increases above a critical value, the system develops global order via the emergence of a macroscopic dipole structure from the homogeneous phase of vortices, spontaneously breaking the Z2 symmetry associated with invariance under vortex circulation exchange, and the rotational SO (2 ) symmetry due to the disk geometry. The dipole structure emerges characterized by the continuous growth of the macroscopic dipole moment which serves as a global order parameter, resembling a continuous phase transition. The critical temperature of the transition, and the critical exponent associated with the dipole moment, are obtained exactly within mean-field theory. The clustering transition is shown to be distinct from the final state reached at high energy, known as supercondensation. The dipole moment develops via two macroscopic vortex clusters and the cluster locations are found analytically, both near the clustering transition and in the supercondensation limit. The microcanonical theory shows excellent agreement with Monte Carlo simulations, and signatures of the transition are apparent even for a modest system of 100
Biofilm-associated infection: the hidden face of cerebrospinal fluid shunt malfunction.
Mounier, Roman; Kapandji, Natacha; Birnbaum, Ron; Cook, Fabrice; Rodriguez, Cristophe; Nebbad, Bibba; Lobo, David; Dhonneur, Gilles
2016-12-01
Diagnosis of cerebrospinal fluid (CSF) shunt infection is difficult. Growing evidence links this pattern to biofilm-associated infections (BAI). Biofilm may explain the indolent development of the infection, and the poor efficiency of traditional microbiologic methods. We report the case of a patient admitted for hydrocephalus associated to CSF shunt malfunction. None of the clinical, serum, or CSF laboratory findings were in favor of an infectious process. Only scanning electron microscopy (SEM) revealed the presence of biofilm. Hence, despite a broad CSF shunt infection definition, some infections could remain undiagnosed by the traditional approach. This study is the first to provide some direct evidence for bacterial biofilm-associated CSF shunt infection.
Schlagenhauf, Florian; Rapp, Michael A; Huys, Quentin J M; Beck, Anne; Wüstenberg, Torsten; Deserno, Lorenz; Buchholz, Hans-Georg; Kalbitzer, Jan; Buchert, Ralph; Bauer, Michael; Kienast, Thorsten; Cumming, Paul; Plotkin, Michail; Kumakura, Yoshitaka; Grace, Anthony A; Dolan, Raymond J; Heinz, Andreas
2013-06-01
Fluid intelligence represents the capacity for flexible problem solving and rapid behavioral adaptation. Rewards drive flexible behavioral adaptation, in part via a teaching signal expressed as reward prediction errors in the ventral striatum, which has been associated with phasic dopamine release in animal studies. We examined a sample of 28 healthy male adults using multimodal imaging and biological parametric mapping with (1) functional magnetic resonance imaging during a reversal learning task and (2) in a subsample of 17 subjects also with positron emission tomography using 6-[(18) F]fluoro-L-DOPA to assess dopamine synthesis capacity. Fluid intelligence was measured using a battery of nine standard neuropsychological tests. Ventral striatal BOLD correlates of reward prediction errors were positively correlated with fluid intelligence and, in the right ventral striatum, also inversely correlated with dopamine synthesis capacity (FDOPA K inapp). When exploring aspects of fluid intelligence, we observed that prediction error signaling correlates with complex attention and reasoning. These findings indicate that individual differences in the capacity for flexible problem solving relate to ventral striatal activation during reward-related learning, which in turn proved to be inversely associated with ventral striatal dopamine synthesis capacity.
Elevated peptides in lung lavage fluid associated with bronchiolitis obliterans syndrome.
Directory of Open Access Journals (Sweden)
Matthew D Stone
Full Text Available OBJECTIVE: The objective of this discovery-level investigation was to use mass spectrometry to identify low mass compounds in bronchoalveolar lavage fluid from lung transplant recipients that associate with bronchiolitis obliterans syndrome. EXPERIMENTAL DESIGN: Bronchoalveolar lavage fluid samples from lung transplant recipients were evaluated for small molecules using ESI-TOF mass spectrometry and correlated to the development of bronchiolitis obliterans syndrome. Peptides associated with samples from persons with bronchiolitis obliterans syndrome and controls were identified separately by MS/MS analysis. RESULTS: The average bronchoalveolar lavage fluid MS spectrum profile of individuals that developed bronchiolitis obliterans syndrome differed greatly compared to controls. Controls demonstrated close inter-sample correlation (R = 0.97+/-0.02, average+/-SD while bronchiolitis obliterans syndrome showed greater heterogeneity (R = 0.86+/-0.09, average+/-SD. We identified 89 features that were predictive of developing BOS grade 1 and 66 features predictive of developing BOS grade 2 or higher. Fractions from MS analysis were pooled and evaluated for peptide content. Nearly 10-fold more peptides were found in bronchiolitis obliterans syndrome relative to controls. C-terminal residues suggested trypsin-like specificity among controls compared to elastase-type enzymes among those with bronchiolitis obliterans syndrome. CONCLUSIONS: Bronchoalveolar lavage fluid from individuals with bronchiolitis obliterans syndrome has an increase in low mass components detected by mass spectrometry. Many of these features were peptides that likely result from elevated neutrophil elastase activity.
Sowers, Susanne Lynn
1997-11-01
Microporous sorbents such as carbons, silicas and aluminas are used commercially in a variety of separation, purification and selective reaction applications. A detailed study of the effects of the porous material characteristics on the adsorption equilibrium properties such as selectivity and phase equilibria of fluid mixtures can enhance our understanding of adsorption on a molecular level. Such knowledge will improve our utilization of such adsorbents and provide a tool for directing the future of tailoring sorbents for particular separation processes. The effect of pore size, shape and pressure on the selective adsorption of trace pollutants from an inert gas was studied using prototype mixtures of Lennard-Tones (LJ) N2/CCl4, CF4, and SO2. Both nonlocal density functional theory (DFT) and grand canonical Monte Carlo (GCMC) molecular simulations were used in order to investigate the validity of the theory, which is much quicker and easier to use. Our results indicate that there is an optimal pore size and shape for which the pollutant selectivity is greatly enhanced. In many industrial adsorption processes relative humidity can greatly affect the life of an adsorbent bed, as seen in breakthrough curves. Therefore, the influence of water vapor on the selective adsorption of CCl4 from a mixture of N2/CCl4/H20 in activated carbon was studied using GCMC simulations. The equilibrium adsorption properties are found to be dependent upon both the density of active sites on the pore walls and the relative humidity. Liquid-liquid transitions in porous materials are of interest in connection with oil recovery, lubrication, coating technology and pollution control. The results of a study on the effect of confinement on the liquid-liquid equilibrium of binary LJ mixtures using DFT are compared with those of molecular simulation and experiments. Our findings show that the phase coexistence for the confined mixture is in general decreased and shifted toward the component which
Hlushak, Stepan P; McCabe, Clare; Cummings, Peter T
2012-09-14
We present a Fourier space density functional approach for hard particles with attractive interactions, which is based on a previously developed two-dimensional approach [S. Hlushak, W. Rżysko, and S. Sokołowski, J. Chem. Phys. 131, 094904 (2009)] for hard-sphere chains. The interactions are incorporated by means of a three-dimensional Fourier image of the direct correlation function that is obtained from the first-order mean-spherical approximation. In order to improve the computational efficiency, we make extensive use of fast Fourier transforms for calculating density convolution integrals. A two-dimensional implementation of the new density functional approach, based on the expansion of the functional around the bulk fluid density, is used to study structure and adsorption of two model fluids in narrow cylindrical pores. We also investigate two methods that improve the accuracy of the theory as compared to the conventional DFT approach, which expands the free energy functional around the bulk fluid density: One a variant of the reference fluid density functional theory used by Gillespie et al. [Phys. Rev. E 68, 031503 (2003)], and the second a weighted density approach with energy route thermodynamics. Results from these two methods are compared to the conventional approach and also to the results of Monte Carlo simulations. We find that the method of Gillespie et al. and the weighted density approach with energy route thermodynamics yield significant improvement over the conventional approach.
On the Study of Second-Order Wave Theory and Its Convergence for a Two-Fluid System
Directory of Open Access Journals (Sweden)
Chi-Min Liu
2013-01-01
Full Text Available Second-order solutions of internal and surface waves in a two-fluid system are theoretically analyzed in this study. Using the perturbation technique, the derivation of second-order solutions for internal waves is revisited, and the results are expressed in one-by-one forms instead of a matrix form. Second-order solutions arising from the interactions of two arbitrary linear waves of different frequencies contain the sum-frequency (superharmonic and the difference-frequency (subharmonic components, which are separately examined. Internal Stokes wave being a special case of present solutions is firstly investigated. Next, the convergence of second-order theory and the second-order effects on wave profiles are analyzed. For general cases, the effects of the thickness ratio of two fluids and the ratio of wavenumbers of two first-order waves on second-order wave characteristics, which include transfer functions and particle velocities, are also examined. Moreover, most existing theories for the one-fluid and two-fluid systems can be deduced from present solutions.
Institute of Scientific and Technical Information of China (English)
Yi-rang Yuan
2007-01-01
For a coupled system of multiplayer dynamics of fluids in porous media,the characteristic finite element domain decomposition procedures applicable to parallel arithmetic are put forward.Techniques such as calculus of variations,domain decomposition,characteristic method,negative norm estimate,energy method and the theory of prior estimates are adopted.Optimal order estimates in L2 norm are derived for the error in the approximate solution.
Judging strangers’ trustworthiness is associated with theory of mind skills
Directory of Open Access Journals (Sweden)
Marie ePrevost
2015-04-01
Full Text Available Trusting people requires evaluating them to assess their trustworthiness. Evaluating a stranger’s intentions is likely to be one method of assessing trustworthiness. The present study tested the hypothesis that judgments of trustworthiness are associated with mindreading skills, also called theory of mind (ToM. We tested a group of healthy participants and a group of patients with paranoid schizophrenia. Both groups made theory of mind judgments and judged the trustworthiness of strangers. Participants were also assessed for their disposition to trust as well as levels of paranoid belief. As anticipated, healthy participants had normal ToM scores and patients with paranoid schizophrenia had poor ToM scores. In paranoid patients, better ability to read others' minds tended to be associated with judging others as more trustworthy, while the reverse was found in the healthy participants (better mind reading was associated with judging others as less trustworthy, suggesting a non-linear relationship between trust in others and being able to read their intentions.
Theory of the vortex-clustering transition in a confined two-dimensional quantum fluid
Yu, Xiaoquan; Nian, Jun; Reeves, Matthew T; Bradley, Ashton S
2016-01-01
Clustering of like-sign vortices in a planar bounded domain is known to occur at negative temperature, a phenomenon that Onsager demonstrated to be a consequence of bounded phase space. In a confined superfluid, quantized vortices can support such an ordered phase, provided they evolve as an almost isolated subsystem containing sufficient energy. A detailed theoretical understanding of the statistical mechanics of such states thus requires a microcanonical approach. Here we develop an analytical theory of the vortex clustering transition in a neutral system of quantum vortices confined to a two-dimensional disk geometry, within the microcanonical ensemble. As the system energy increases above a critical value, the system develops global order via the emergence of a macroscopic dipole structure from the homogeneous phase of vortices, spontaneously breaking the Z2 symmetry associated with invariance under vortex circulation exchange, and the rotational SO(2) symmetry due to the disk geometry. The dipole structu...
Groesen, E. van; Verstappen, R.W.C.P.
1990-01-01
This paper discusses the variational structure of the line contact problem between an elastic medium and a fluid. The equations for the deformation in the elastic material, and for the flow of the viscous fluid are assumed to be determined from an elastic energy E and a power functional P respective
Theoretical models for fluid thermodynamics based on the quasi-Gaussian entropy theory
Amadei, Andrea
1998-01-01
Summary The theoretical modeling of fluid thermodynamics is one of the most challenging fields in physical chemistry. In fact the fluid behavior, except at very low density conditions, is still extremely difficult to be modeled from a statistical mechanical point of view, as for any realistic model
Absi, Rafik; Dufour, Florence; Huet, Denis; Bennacer, Rachid; Absi, Tahar
2011-01-01
EBI is a further education establishment which provides education in applied industrial biology at level of MSc engineering degree. Fluid mechanics at EBI was considered by students as difficult who seemed somewhat unmotivated. In order to motivate them, we applied a new play-based pedagogy. Students were asked to draw inspiration from everyday life situations to find applications of fluid mechanics and to do experiments to verify and validate some theoretical results obtained in course. In this paper, we present an innovative teaching/learning pedagogy which includes the concept of learning through play and its implications in fluid mechanics for engineering. Examples of atypical experiments in fluid mechanics made by students are presented. Based on teaching evaluation by students, it is possible to know how students feel the course. The effectiveness of this approach to motivate students is presented through an analysis of students' teaching assessment. Learning through play proved a great success in fluid...
"Low Testosterone Levels in Body Fluids Are Associated With Chronic Periodontitis".
Kellesarian, Sergio Varela; Malmstrom, Hans; Abduljabbar, Tariq; Vohra, Fahim; Kellesarian, Tammy Varela; Javed, Fawad; Romanos, Georgios E
2017-03-01
There is a debate over the association between low testosterone levels in body fluids and the occurrence of chronic periodontitis (CP). The aim of the present systematic review was to assess whether low testosterone levels in body fluids reflect CP. In order to identify studies relevant to the focus question: "Is there a relationship between low testosterone levels in body fluids and CP?" an electronic search without time or language restrictions was conducted up to June 2016 in indexed databases using different keywords: periodontitis, chronic periodontitis, periodontal diseases, testosterone, and gonadal steroid hormones. A total of eight studies were included in the present systematic review. The number of study participants ranged from 24 to 1,838 male individuals with ages ranging from 15 to 95 years. Seven studies measured testosterone levels in serum, two studies in saliva, and one study in gingiva. Four studies reported a negative association between serum testosterone levels and CP. Two studies reported a positive association between decreased testosterone levels in serum and CP. Increased levels of salivary testosterone among patients with CP were reported in one study; whereas one study reported no significant difference in the concentration of salivary testosterone between patients with and without CP. One study identified significant increase in the metabolism of testosterone in the gingiva of patients with CP. Within the limits of the evidence available, the relationship between low testosterone levels and CP remains debatable and further longitudinal studies and control trials are needed.
Association between fetal weight and amniotic fluid index in women of Central India
Directory of Open Access Journals (Sweden)
Nitin Wadnere
2014-01-01
Full Text Available Background : The placenta is important for fetal growth and well-being. Defective placentation and impaired placental circulation may result in anomalies in fetal growth. Placental volume in the second trimester appears to be closely related to the neonatal weight. The association of body weight with urine output has been observed in human neonates. Our goal is to assess the association of the amniotic fluid index (AFI with the estimated fetal weight (EFW. Materials and Methods : Thirteen hundred and ninety-three pregnant women were prospectively studied by means of an ultrasound over a 12-month period. The fetal weight (FW was estimated using a combination of fetal parameters - bi-parietal diameter, fetal trunk cross-sectional area, and femur length. AFI was assessed using the four quadrant method. The level of statistical significance was set at P ≤ 0.05. Result s: There was no statistically significant association between AFI and EFW (P > 0.05; r = 0.413. We also did not find a significant association between AFI and EFW for all subdivisions of gestation age, except in the 24 - 28 weeks and 29 - 32 weeks′ groups. Conclusion : The FW calculations and amniotic index show a variation in values in late pregnancy. There does not appear to be a linear association between the ultrasound estimate of FW and the amniotic index. The implication of this is that the fetal size need not be taken into cognizance when alterations in amniotic fluid values are noted.
Spyridaki, Eirini C; Simos, Panagiotis; Avgoustinaki, Pavlina D; Dermitzaki, Eirini; Venihaki, Maria; Bardos, Achilles N; Margioris, Andrew N
2014-11-28
Published evidence suggests that obesity impairs cognition. Development of chronic low-grade inflammation (CLGI) represents the earliest consequence of obesity. The present study investigated the association between obesity and fluid intelligence impairment and assessed the potential mediating role of CLGI and psychological (depression/anxiety symptoms), lifestyle (exercise) and physiological (metabolic dysfunction indices) factors in this association. Clinically healthy participants (n 188), grouped as per BMI, underwent cognitive (General Ability Measure for Adults), psychological (Beck Depression Inventory-II and State-Trait Anxiety Inventory) and activity (Godin leisure-time physical activity) measurements. Biochemical parameters included the following: (a) indices of CLGI (high-sensitivity C-reactive protein, erythrocyte sedimentation rate and fibrinogen); (b) insulin resistance (Homeostasis Model Assessment of Insulin Resistance index); (c) adiposity (plasma adiponectin). An inverse association between elevated BMI and fluid intelligence was observed, with obese participants displaying significantly poorer performance compared with age-matched normal-weight peers. Structural equation modelling results were consistent with a negative impact of obesity on cognition that was mediated by CLGI. The results of the present study support the hypothesis that reduced general cognitive ability is associated with obesity, an adverse effect mainly mediated by obesity-associated activation of innate immunity.
Note on scalars, perfect fluids, constrained field theories, and all that
Diez-Tejedor, Alberto
2013-01-01
The relation of a scalar field with a perfect fluid has generated some debate along the last few years. In this paper we argue that shift-invariant scalar fields can describe accurately the potential flow of an isentropic perfect fluid, but, in general, the identification is possible only for a finite period of time. After that period in the evolution the dynamics of the scalar field and the perfect fluid branch off. The Lagrangian density for the velocity-potential can be read directly from the expression relating the pressure with the Taub charge and the entropy per particle in the fluid, whereas the other quantities of interest can be obtained from the thermodynamic relations.
Note on scalars, perfect fluids, constrained field theories, and all that
Energy Technology Data Exchange (ETDEWEB)
Diez-Tejedor, Alberto
2013-11-25
The relation of a scalar field with a perfect fluid has generated some debate along the last few years. In this Letter we argue that shift-invariant scalar fields can describe accurately the potential flow of an isentropic perfect fluid, but, in general, the identification is possible only for a finite period of time. After that period in the evolution the dynamics of the scalar field and the perfect fluid branch off. The Lagrangian density for the velocity-potential can be read directly from the expression relating the pressure with the Taub charge and the entropy per particle in the fluid, whereas the other quantities of interest can be obtained from the thermodynamic relations.
Hung, R. J.; Liaw, G. S.
1980-01-01
It is noted that large quantities of atmospheric aerosols with composition SO4(-2), NO3(-1), and NH4(+1) have been detected in highly industrialized areas. Most aerosol products come from energy-related fuel combustion. Fluid mechanics simulation of both microphysical and macrophysical processes is considered in studying the time dependent evolution of the saturation spectra of condensation nuclei associated with polluted and clean atmospheres during the time periods of advection fog formation. The results demonstrate that the condensation nuclei associated with a polluted atmosphere provide more favorable conditions than condensation nuclei associated with a clean atmosphere to produce dense advection fog, and that attaining a certain degree of supersaturation is not necessarily required for the formation of advection fog having condensation nuclei associated with a polluted atmosphere.
Okamoto, Ryuichi; Onuki, Akira
2012-03-21
We investigate the critical behavior of a near-critical fluid confined between two parallel plates in contact with a reservoir by calculating the order parameter profile and the Casimir amplitudes (for the force density and for the grand potential). Our results are applicable to one-component fluids and binary mixtures. We assume that the walls absorb one of the fluid components selectively for binary mixtures. We propose a renormalized local functional theory accounting for the fluctuation effects. Analysis is performed in the plane of the temperature T and the order parameter in the reservoir ψ(∞). Our theory is universal if the physical quantities are scaled appropriately. If the component favored by the walls is slightly poor in the reservoir, there appears a line of first-order phase transition of capillary condensation outside the bulk coexistence curve. The excess adsorption changes discontinuously between condensed and noncondensed states at the transition. With increasing T, the transition line ends at a capillary critical point T=T(c) (ca) slightly lower than the bulk critical temperature T(c) for the upper critical solution temperature. The Casimir amplitudes are larger than their critical point values by 10-100 times at off-critical compositions near the capillary condensation line.
Hesse, Michael; Birn, Joachim; Schindler, Karl
1990-01-01
A self-consistent two-fluid theory that includes the magnetic field and shear patterns is developed to model stationary electrostatic structures with field-aligned potential drops. Shear flow is also included in the theory since this seems to be a prominent feature of the structures of interest. In addition, Ohmic dissipation, a Hall term, and pressure gradients in a generalized Ohm's law, modified for cases without quasi-neutrality, are included. In the analytic theory, the electrostatic force is balanced by field-aligned pressure gradients (i.e., thermal effects in the direction of the magnetic field) and by pressure gradients and magnetic stresses in the perpendicular direction. Within this theory, simple examples of applications are presented to demonstrate the kind of solutions resulting from the model. The results show how the effects of charge separation and shear in the magnetic field and the velocity can be combined to form self-consistent structures such as are found to exist above the aurora, suggested also in association with solar flares.
Solvation of polymers as mutual association. I. General theory
Dudowicz, Jacek; Freed, Karl F.; Douglas, Jack F.
2013-04-01
A Flory-Huggins (FH) type lattice theory of self-assembly is generalized to describe the equilibrium solvation of long polymer chains B by small solvent molecules A. Solvation is modeled as a thermally reversible mutual association between the polymer and a relatively low molar mass solvent. The FH Helmholtz free energy F is derived for a mixture composed of the A and B species and the various possible mutual association complexes AiB, and F is then used to generate expressions for basic thermodynamic properties of solvated polymer solutions, including the size distribution of the solvated clusters, the fraction of solvent molecules contained in solvated states (an order parameter for solvation), the specific heat (which exhibits a maximum at the solvation transition), the second and the third osmotic virial coefficients, and the boundaries for phase stability of the mixture. Special attention is devoted to the analysis of the "entropic" contribution χs to the FH interaction parameter χ of polymer solutions, both with and without associative interactions. The entropic χs parameter arises from correlations associated with polymer chain connectivity and disparities in molecular structure between the components of the mixture. Our analysis provides the first explanation of the longstanding enigma of why χs for polymer solutions significantly exceeds χs for binary polymer blends. Our calculations also reveal that χs becomes temperature dependent when interactions are strong, in sharp contrast to models currently being used for fitting thermodynamic data of associating polymer-solvent mixtures, where χs is simply assumed to be an adjustable constant based on experience with solutions of homopolymers in nonassociating solvents.
THEORY AND EXPERIMENT ON THE VISCOUS HEATING OF FLUID DAMPER UNDER SHOCK ENVIRONMENT
Institute of Scientific and Technical Information of China (English)
CHU Deying; ZHANG Zhiyi; WANG Gongxian; HUA Hongxing; WANG Yu
2008-01-01
A specially designed fluid damper used as negative shock pulse generator in the shock resistance test system to dissipate the shock input energy in transient time duration is presented. The theoretical modeling based on the three-dimensional equation of heat transfer through a fluid element is created to predict the viscous heating in the fluid damper under shock conditions. A comprehensive experimental program that investigates the problem of viscous heating in the fluid damper under different shock conditions is conducted on the shock test machine to validate the analytical expression. Temperature histories for the fluid within the damper at two locations, the annular-orifice and the-end-of stroke of the damper, are recorded. The experimental results show that the theoretical model can offer a very dependable prediction for the temperature histories in the damper for increasing input velocity. The theoretical model and experimental data both clearly indicate that the viscous heating in the damper is directly related to the maximum shock velocity input and the pressure between the two sides of the piston head.
Institute of Scientific and Technical Information of China (English)
N. P. Gaikwad; M. S. Borkar; S. S. Charjan
2011-01-01
@@ We investigate the Bianchi type-I massive string magnetized barotropic perfect fluid cosmological model in Rosen's bimetric theory of gravitation with and without a magnetic field by applying the techniques used by Latelier(1979,1980) and Stachel(1983).To obtain a deterministic model of the universe, it is assumed that the universe is filled with barotropic perfect fluid distribution.The physical and geometrical significance of the model are discussed.By comparing our model with the model of Bali et al.(2007), it is realized that there are no big-bang and big-crunch singularities in our model and T＝0 is not the time of the big bang, whereas the model of Bali et al.starts with a big bang at T=0.Further, our model is in agreement with Bali et al.(2007) as time increases in the presence, as well as in the absence, of a magnetic field.
DEFF Research Database (Denmark)
Zuo, You-Xiang; Stenby, Erling Halfdan
1997-01-01
In this research work, the gradient theory (GT) of inhomogeneous fluids was used to calculate interfacial tensions (IFTs). The correlations of the influence parameter are presented for pure hydrocarbons, which can improve the scaling behavior of pure fluids under near-critical conditions. The ove...... the agreement is reasonably accurate in the near-critical region as the models reveal classical scaling behavior. To predict low IFTs accurately ((sigma)....... The overall average absolute deviations (ADDs) of the calculated IFTs from the GT model with the SRK, PR and PT equations of state (EOS´s) for 86 non-polar and weakly polar pure substances are 2.34%, 2.10% and 2.29%, respectively. At low pressure, the lumping method proposed by Leibovici [Leibovici, C.F, 1993...
Houben, M.L.; Olde Nordkamp, M.J.M.; Nikkels, P.G.J.; van der Ent, C.K.; Meyaard, L.; Bont, L.J.
2013-01-01
The soluble form of the inhibitory immune receptor leukocyte-Associated Ig-like Receptor-1 (sLAIR-1) is present in plasma, urine and synovial fluid and correlates to inflammation. We and others previously showed inflammatory protein expression in normal amniotic fluid at term. We hypothesized that s
Isobaric thermal expansivity behaviour against temperature and pressure of associating fluids
Energy Technology Data Exchange (ETDEWEB)
Navia, Paloma; Troncoso, Jacobo [Departamento de Fisica Aplicada, Facultad de Ciencias de Ourense, Campus As Lagoas, 32004 Ourense (Spain); Romani, Luis, E-mail: romani@uvigo.e [Departamento de Fisica Aplicada, Facultad de Ciencias de Ourense, Campus As Lagoas, 32004 Ourense (Spain)
2010-01-15
In order to study the influence of association on the isobaric thermal expansivity, this magnitude has been experimentally determined for a set of associating fluids within the temperature and pressure intervals (278.15 to 348.15) K and (5 to 55) MPa by means of calorimetric measurements. The 1-alcohol series, from methanol to 1-decanol, 2-pentanol, 3-pentanol, and 1-pentylamine were selected. With a view on checking the quality of the experimental data, they are compared with available literature values; good coherence was obtained for most of the studied liquids. The analysis of the experimental results reveals that the association capability presents a strong influence not only on the value of the isobaric thermal expansivity itself, but also on its behaviour against temperature and pressure.
LENUS (Irish Health Repository)
O'Daly, Brendan J
2009-06-01
BACKGROUND: Predicting the clinical course in adhesional small bowel obstruction is difficult. There are no validated clinical or radiologic features that allow early identification of patients likely to require surgical intervention. METHODS: We conducted a retrospective review of 100 patients consecutively admitted to a tertiary level teaching hospital over a 3-year period (2002-2004) who had acute adhesional small bowel obstruction and underwent computed tomography (CT). The primary outcomes that we assessed were conservative management or the need for surgical intervention. We investigated time to physiologic gastrointestinal function recovery as a secondary outcome. We examined independent predictors of surgical intervention in a bivariate analysis using a stepwise logistic regression analysis. RESULTS: Of the 100 patients investigated, we excluded 12. Of the 88 remaining patients, 58 (66%) were managed conservatively and 30 (34%) underwent surgery. Peritoneal fluid detected on a CT scan (n = 37) was associated more frequently with surgery than conservative management (46% v. 29%, p = 0.046, chi(2)). Logistical regression identified peritoneal fluid detected on a CT scan as an independent predictor of surgical intervention (odds ratio 3.0, 95% confidence interval 1.15-7.84). CONCLUSION: The presence of peritoneal fluid on a CT scan in patients with adhesional small bowel obstruction is an independent predictor of surgical intervention and should alert the clinician that the patient is 3 times more likely to require surgery.
Wu, Chia-Lung; Kimmerling, Kelly A.; Little, Dianne; Guilak, Farshid
2017-01-01
High-fat diet-induced obesity is a major risk factor for osteoarthritis (OA) and diminished wound healing. The objective of this study was to determine the associations among serum and synovial fluid lipid levels with OA, synovitis, adipokine levels, and wound healing in a pre-clinical obese mouse model of OA. Male C57BL/6 J mice were fed either a low-fat (10% kcal) or one of three high-fat (HF, 60% kcal) diets rich in saturated fatty acids (SFAs), ω-6 or ω-3 polyunsaturated FAs (PUFAs). OA was induced by destabilization of the medial meniscus. Mice also received an ear punch for evaluating wound healing. Serum and synovial fluid were collected for lipidomic and adipokine analyses. We demonstrated that the serum levels of ω-3 PUFAs were negatively correlated with OA and wound size, but positively correlated with adiponectin levels. In contrast, most ω-6 PUFAs exhibited positive correlations with OA, impaired healing, and inflammatory adipokines. Interestingly, levels of pentadecylic acid (C15:0, an odd-chain SFA) and palmitoleic acid were inversely correlated with joint degradation. This study extends our understanding of the links of FAs with OA, synovitis and wound healing, and reports newly identified serum and synovial fluid FAs as predictive biomarkers of OA in obesity. PMID:28317846
Diffusion of particles in simple fluids: A joint theory of kinetics and hydrodynamics
Zhao, Hanqing
2016-01-01
The particle diffusion in a fluid is a classical topic that dates back to more than one century ago. However, a full solution to this issue still lacks. In this work the velocity autocorrelation function and the diffusion constant are derived analytically, and the hydrodynamics effect on the particle diffusion is analyzed in detail. Unlike previous studies, the ring-collision effect is exhaustively considered in our treatment, and the hydrodynamics approach is extended to the whole time range. Large scale molecular dynamics simulations for the hard-disk fluid show that our analytical results are valid up to the density close to the crystallization point.
The Alzheimer's Association external quality control program for cerebrospinal fluid biomarkers
DEFF Research Database (Denmark)
Mattsson, Niklas; Andreasson, Ulf; Persson, Staffan
2011-01-01
. The Alzheimer's Association has initiated a global quality control program to estimate and monitor variability of measurements, quantify batch-to-batch assay variations, and identify sources of variability. In this article, we present the results from the first two rounds of the program.......The cerebrospinal fluid (CSF) biomarkers amyloid β (Aβ)-42, total-tau (T-tau), and phosphorylated-tau (P-tau) demonstrate good diagnostic accuracy for Alzheimer's disease (AD). However, there are large variations in biomarker measurements between studies, and between and within laboratories...
Lipid-associated sialic acid levels in human breast cyst fluids.
Mannello, F; Bocchiotti, G; Troccoli, R; Gazzanelli, G
1992-01-01
Benign mammary gross cystic disease is the most common breast lesion. Women with apocrine changes of epithelium lining the cysts are at higher risk for developing breast cancer than the normal female population. Sialic acid has drawn considerable interest because of carbohydrate aberrations in malignant cells. The current investigation determined the concentrations of lipid-associated sialic acid (LASA) in 62 breast cyst fluids and sera. Data analyses show a significant increase in the mean values of LASA in metabolically active apocrine cysts when compared to the cysts with Na+/K+ > 3 (flattened cysts) (p breast cancer.
Directory of Open Access Journals (Sweden)
Fei Zhu
Full Text Available BACKGROUND: Excessive mechanical loading of articular cartilage producing hydrostatic stress, tensile strain and fluid flow leads to irreversible cartilage erosion and osteoarthritic (OA disease. Since application of high fluid shear to chondrocytes recapitulates some of the earmarks of OA, we aimed to screen the gene expression profiles of shear-activated chondrocytes and assess potential similarities with OA chondrocytes. METHODOLOGY/PRINCIPAL FINDINGS: Using a cDNA microarray technology, we screened the differentially-regulated genes in human T/C-28a2 chondrocytes subjected to high fluid shear (20 dyn/cm(2 for 48 h and 72 h relative to static controls. Confirmation of the expression patterns of select genes was obtained by qRT-PCR. Using significance analysis of microarrays with a 5% false discovery rate, 71 and 60 non-redundant transcripts were identified to be ≥2-fold up-regulated and ≤0.6-fold down-regulated, respectively, in sheared chondrocytes. Published data sets indicate that 42 of these genes, which are related to extracellular matrix/degradation, cell proliferation/differentiation, inflammation and cell survival/death, are differentially-regulated in OA chondrocytes. In view of the pivotal role of cyclooxygenase-2 (COX-2 in the pathogenesis and/or progression of OA in vivo and regulation of shear-induced inflammation and apoptosis in vitro, we identified a collection of genes that are either up- or down-regulated by shear-induced COX-2. COX-2 and L-prostaglandin D synthase (L-PGDS induce reactive oxygen species production, and negatively regulate genes of the histone and cell cycle families, which may play a critical role in chondrocyte death. CONCLUSIONS/SIGNIFICANCE: Prolonged application of high fluid shear stress to chondrocytes recapitulates gene expression profiles associated with osteoarthritis. Our data suggest a potential link between exposure of chondrocytes/cartilage to abnormal mechanical loading and the pathogenesis
Analytical Thermal Field Theory Applicable to Oil Hydraulic Fluid Film Lubrication
DEFF Research Database (Denmark)
Johansen, Per; Roemer, Daniel Beck; Pedersen, Henrik C.
2014-01-01
An analytical thermal field theory is derived by a perturbation series expansion solution to the energy conservation equation. The theory is valid for small values of the Brinkman number and the modified Peclet number. This condition is sufficiently satisfied for hydraulic oils, whereby the analy...
DEFF Research Database (Denmark)
Jødal, Lars
The lecture notes describe how body fluid volumes can be measured/estimated using the technique bio-impedance spectroscopy (BIS). The opening chapters assume little or none technical/mathematical knowledge and can hopefully be read by anyone interested in the techneque. Later chapters become more...
DEFF Research Database (Denmark)
Ristinmaa, M.; Ottosen, N.S.; Johannesson, Björn
2011-01-01
A thermoelastic-plastic body consisting of two phases, a solid and a fluid, each comprising two constituents is considered where one constituent in one phase is allowed to exchange mass with another constituent (of the same substance) in the other phase. A large strain setting is adopted and the ...
A variational principle for compressible fluid mechanics: Discussion of the multi-dimensional theory
Prozan, R. J.
1982-01-01
The variational principle for compressible fluid mechanics previously introduced is extended to two dimensional flow. The analysis is stable, exactly conservative, adaptable to coarse or fine grids, and very fast. Solutions for two dimensional problems are included. The excellent behavior and results lend further credence to the variational concept and its applicability to the numerical analysis of complex flow fields.
Physical Theory of Narrow-Band Sounds Associated with Intracranial Aneurysms
Mast, T. Douglas
Intracranial aneurysms in humans are sometimes associated with narrow-band sound. The sounds of interest have frequencies on the order of 500 Hz. Bandwidths observed correspond to quality factors on the order of 30. The present thesis offers a physical theory of the mechanism of excitation of these sounds. It is shown that an aneurysm can be modeled as a lumped-element resonator in which the kinetic energy is associated with the motion of blood in the neck of the aneurysm and the potential energy is stored in the flexible walls of the aneurysm sac. However, the quality factors of aneurysms as lumped-element resonators are seen to be much smaller than the observed quality factors of aneurysm sounds, so that aneurysm sounds cannot be explained as a simple resonance phenomenon associated with external forcing. It is shown that the best explanation for aneurysm sounds is a self-excited oscillation of the system comprised of the aneurysm and the unstable mean flow; this oscillation is explained quantitatively here for the first time. In the theory developed in this thesis, limit cycles of the aneurysm-flow system are found using describing -function analysis. Results of the theory agree quantitatively with experiments performed on flow-excited Helmholtz resonators and agree qualitatively with the observed characteristics of aneurysm sounds. The bandwidths of observed aneurysm sounds for a time-varying mean flow are predicted and compared with bandwidths of sounds due to periodic vortex shedding in the absence of any resonator. It is shown that the presence of a resonator causes a locking-in of the flow disturbances to the sounding frequency of the resonator, resulting in a narrow observed bandwidth, even for a time -varying mean flow. Bandwidth considerations make it possible to distinguish sounds associated with self-excited oscillations of aneurysms from sounds due to purely fluid-mechanical mechanisms. The theory presented here can be taken as a starting point for
Towards a non-linear theory for fluid pressure and osmosis in shales
Droghei, Riccardo; Salusti, Ettore
2015-04-01
In exploiting deep hydrocarbon reservoirs, often injections of fluid and/or solute are used. To control and avoid troubles as fluid and gas unexpected diffusions, a reservoir characterization can be obtained also from observations of space and time evolution of micro-earthquake clouds resulting from such injections. This is important since several among the processes caused by fluid injections can modify the deep matrix. Information about the evolution of such micro-seismicity clouds therefore plays a realistic role in the reservoir analyses. To reach a better insight about such processes, and obtain a better system control, we here analyze the initial stress necessary to originate strong non linear transients of combined fluid pressure and solute density (osmosis) in a porous matrix. All this can indeed perturb in a mild (i.e. a linear diffusion) or dramatic non linear way the rock structure, till inducing rock deformations, micro-earthquakes or fractures. I more detail we here assume first a linear Hooke law relating strain, stress, solute density and fluid pressure, and analyze their effect in the porous rock dynamics. Then we analyze its generalization, i.e. the further non linear effect of a stronger external pressure, also in presence of a trend of pressure or solute in the whole region. We moreover characterize the zones where a sudden arrival of such a front can cause micro-earthquakes or fractures. All this allows to reach a novel, more realistic insight about the control of rock evolution in presence of strong pressure fronts. We thus obtain a more efficient reservoir control to avoid large geological perturbations. It is of interest that our results are very similar to those found by Shapiro et al.(2013) with a different approach.
Institute of Scientific and Technical Information of China (English)
Fu Dong; Liao Tao
2007-01-01
The excess Helmholtz free energy functional for nonpolar chain-like molecules is formulated in terms of a weighted density approximation (WDA) for short-range interactions and a Weaks-Chandler-Andersen (WCA) approximation and a Barker-Henderson (BH) theory for long-range attraction. Within the framework of density functional theory (DFT), vapour-liquid interfacial properties including density profile and surface tension, and vapour-liquid nucleation properties including density profile, work of formation and number of particles are investigated for spherical and chainlike molecules. The obtained vapour-liquid surface tension and the number of particles in critical nucleus for LennardJones (L J) fluids are consistent with the simulation results. The influences of supersaturation, temperature and chain length on vapour-liquid nucleation properties are discussed.
Andreou, Dimitrios; Söderman, Erik; Axelsson, Tomas; Sedvall, Göran C; Terenius, Lars; Agartz, Ingrid; Jönsson, Erik G
2016-04-21
Dopamine activity, mediated by the catecholaminergic neurotransmitter dopamine, is prominent in the human brain and has been implicated in schizophrenia. Dopamine targets five different receptors and is then degraded to its major metabolite homovanillic acid (HVA). We hypothesized that genes encoding dopamine receptors may be associated with cerebrospinal fluid (CSF) HVA concentrations in patients with psychotic disorder. We searched for association between 67 single nucleotide polymorphisms (SNPs) in the five dopamine receptor genes i.e., DRD1, DRD2, DRD3, DRD4 and DRD5, and the CSF HVA concentrations in 74 patients with psychotic disorder. Nominally associated SNPs were also tested in 111 healthy controls. We identified a locus, located downstream DRD1 gene, where four SNPs, rs11747728, rs11742274, rs265974 and rs11747886, showed association with CSF HVA concentrations in psychotic patients. The associations between rs11747728, which is a regulatory region variant, and rs11742274 with HVA remained significant after correction for multiple testing. These associations were restricted to psychotic patients and were absent in healthy controls. The results suggest that the DRD1 gene is implicated in the pathophysiology of psychosis and support the dopamine hypothesis of schizophrenia.
Directory of Open Access Journals (Sweden)
Zhongheng Zhang
2015-02-01
Full Text Available Background and Objective. Acute respiratory distress syndrome (ARDS is characterized by pulmonary edema and may benefit from conservative fluid management. However, conflicting results exist in the literature. The study aimed to investigate the association between mean fluid balance and mortality outcome in ARDS patients who required invasive mechanical ventilation.Methods. The study was a secondary analysis of a prospectively collected dataset obtained from the NHLBI Biologic Specimen and Data Repository Information Coordinating Center. ARDS patients with invasive mechanical ventilation were eligible. Demographic and laboratory data were extracted from the dataset. Multivariable regression model was built by stepwise selection of covariates. A fractional polynomial approach was used to test the linearity of mean fluid balance in the model. The potential interactions of mean fluid balance with other variables were tested.Main Results. A total of 282 patients were eligible for the analysis, including 61 non-survivors with a mortality rate of 21.6%. After stepwise regression analysis, mean fluid balance remained to be an independent predictor of death (OR: 1.00057; 95% CI [1.00034–1.00080]. The two-term model obtained using fractional polynomial analysis was not superior to the linear model. There was significant interaction between mean fluid balance and serum potassium levels (p = 0.011. While the risk of death increased with increasing mean fluid balance at potassium levels of 1.9, 2.9 , 3.9 and 4.9 mmol/l, the risk decreased at potassium level of 5.9 mmol/l.Conclusion. The present study demonstrates that more positive fluid balance in the first 8 days is significantly associated with increased risk of death. However, the relationship between mean fluid balance and mortality can be modified by serum potassium levels. With hyperkalemia, more positive fluid balance is associated with reduced risk of death.
Coe, Joshua D; Sewell, Thomas D; Shaw, M Sam
2009-08-21
An optimized variant of the nested Markov chain Monte Carlo [n(MC)(2)] method [J. Chem. Phys. 130, 164104 (2009)] is applied to fluid N(2). In this implementation of n(MC)(2), isothermal-isobaric (NPT) ensemble sampling on the basis of a pair potential (the "reference" system) is used to enhance the efficiency of sampling based on Perdew-Burke-Ernzerhof density functional theory with a 6-31G(*) basis set (PBE6-31G(*), the "full" system). A long sequence of Monte Carlo steps taken in the reference system is converted into a trial step taken in the full system; for a good choice of reference potential, these trial steps have a high probability of acceptance. Using decorrelated samples drawn from the reference distribution, the pressure and temperature of the full system are varied such that its distribution overlaps maximally with that of the reference system. Optimized pressures and temperatures then serve as input parameters for n(MC)(2) sampling of dense fluid N(2) over a wide range of thermodynamic conditions. The simulation results are combined to construct the Hugoniot of nitrogen fluid, yielding predictions in excellent agreement with experiment.
Statistical mechanical theory for and simulations of charged fluids and water
Rodgers, Jocelyn Michelle
Treatment of electrostatic interactions in simulations remains a topic of current research. These interactions are present in most biomolecular simulations, and they remain an expensive part of the simulation. Herein we explore the application of local molecular field (LMF) theory to this problem. Local molecular field theory splits the Coulomb potential 1/r into short-ranged and long-ranged components. The short-ranged component may be treated explicitly in simulations and the long-ranged component is contained in a mean-field-like average external electrostatic potential. In this thesis, the derivations and approximations inherent in using the previously developed LMF theory are explored, and connections to classical electrostatics are made. Further the approach is justified for molecular systems. The application of LMF theory to several systems is explored. First, a simple system of uniformly charged walls with neutralizing counterions is treated via simulations using LMF theory. We then explore systems involving molecular water at ambient conditions. A simple approximation to LMF theory using only the short-ranged component of 1/r is quite powerful for bulk water. A full treatment using LMF theory extends the validity of such spherical truncations to nonuniform systems. This thesis studies the successful treatment of water confined between hydrophobic walls with and without an applied electric field---a system which is a classic example of the failings of spherical truncations in molecular simulations. Additional results exemplify the applicability of LMF simulations to more molecularly realistic simulations. Connection is also made between these simulations of confined water and a related theory of hydrophobicity due to Lum, Chandler, and Weeks (1999).
Fluid-solid transition in simple systems using density functional theory
Energy Technology Data Exchange (ETDEWEB)
Bharadwaj, Atul S.; Singh, Yashwant [Department of Physics, Banaras Hindu University, Varanasi-221 005 (India)
2015-09-28
A free energy functional for a crystal which contains both the symmetry-conserved and symmetry-broken parts of the direct pair correlation function has been used to investigate the fluid-solid transition in systems interacting via purely repulsive Weeks-Chandler-Anderson Lennard–Jones potential and the full Lennard–Jones potential. The results found for freezing parameters for the fluid-face centred cubic crystal transition are in very good agreement with simulation results. It is shown that although the contribution made by the symmetry broken part to the grand thermodynamic potential at the freezing point is small compared to that of the symmetry conserving part, its role is crucial in stabilizing the crystalline structure and on values of the freezing parameters.
Coupling LAMMPS with Lattice Boltzmann fluid solver: theory, implementation, and applications
Tan, Jifu; Sinno, Talid; Diamond, Scott
2016-11-01
Studying of fluid flow coupled with solid has many applications in biological and engineering problems, e.g., blood cell transport, particulate flow, drug delivery. We present a partitioned approach to solve the coupled Multiphysics problem. The fluid motion is solved by the Lattice Boltzmann method, while the solid displacement and deformation is simulated by Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). The coupling is achieved through the immersed boundary method so that the expensive remeshing step is eliminated. The code can model both rigid and deformable solids. The code also shows very good scaling results. It was validated with classic problems such as migration of rigid particles, ellipsoid particle's orbit in shear flow. Examples of the applications in blood flow, drug delivery, platelet adhesion and rupture are also given in the paper. NIH.
Scalar-Fluid theories: cosmological perturbations and large-scale structure
Koivisto, Tomi S; Tamanini, Nicola
2015-01-01
Recently a new Lagrangian framework was introduced to describe interactions between scalar fields and relativistic perfect fluids. This allows two consistent generalizations of coupled quintessence models: non-vanishing pressures and a new type of derivative interaction. Here the implications of these to the formation of cosmological large-scale structure are uncovered at the linear order. The full perturbation equations in the two cases are derived in a unified formalism and their Newtonian, quasi-static limit is studied analytically. Requiring the absence of an effective sound speed for the coupled dark matter fluid restricts the Lagrangian to be a linear function of the matter number density. This still leaves new potentially viable classes of both algebraically and derivatively interacting models wherein the coupling may impact the background expansion dynamics and imprint signatures into the large-scale structure.
Hughes, Adam P.; Thiele, Uwe; Archer, Andrew J.
2017-02-01
For a film of liquid on a solid surface, the binding potential g(h) gives the free energy as a function of the film thickness h and also the closely related (structural) disjoining pressure Π =-∂g /∂h . The wetting behaviour of the liquid is encoded in the binding potential and the equilibrium film thickness corresponds to the value at the minimum of g(h). Here, the method we developed in the work of Hughes et al. [J. Chem. Phys. 142, 074702 (2015)], and applied with a simple discrete lattice-gas model, is used with continuum density functional theory (DFT) to calculate the binding potential for a Lennard-Jones fluid and other simple liquids. The DFT used is based on fundamental measure theory and so incorporates the influence of the layered packing of molecules at the surface and the corresponding oscillatory density profile. The binding potential is frequently input in mesoscale models from which liquid drop shapes and even dynamics can be calculated. Here we show that the equilibrium droplet profiles calculated using the mesoscale theory are in good agreement with the profiles calculated directly from the microscopic DFT. For liquids composed of particles where the range of the attraction is much less than the diameter of the particles, we find that at low temperatures g(h) decays in an oscillatory fashion with increasing h, leading to highly structured terraced liquid droplets.
LENUS (Irish Health Repository)
McNally, P
2012-02-01
BACKGROUND: Gastro-oesophageal reflux is common in children with cystic fibrosis (CF) and is thought to be associated with pulmonary aspiration of gastric contents. The measurement of pepsin in bronchoalveolar lavage (BAL) fluid has recently been suggested to be a reliable indicator of aspiration. The prevalence of pulmonary aspiration in a group of children with CF was assessed and its association with lung inflammation investigated. METHODS: This was a cross-sectional case-control study. BAL fluid was collected from individuals with CF (n=31) and healthy controls (n=7). Interleukin-8 (IL-8), pepsin, neutrophil numbers and neutrophil elastase activity levels were measured in all samples. Clinical, microbiological and lung function data were collected from medical notes. RESULTS: The pepsin concentration in BAL fluid was higher in the CF group than in controls (mean (SD) 24.4 (27.4) ng\\/ml vs 4.3 (4.0) ng\\/ml, p=0.03). Those with CF who had raised pepsin concentrations had higher levels of IL-8 in the BAL fluid than those with a concentration comparable to controls (3.7 (2.7) ng\\/ml vs 1.4 (0.9) ng\\/ml, p=0.004). Within the CF group there was a moderate positive correlation between pepsin concentration and IL-8 in BAL fluid (r=0.48, p=0.04). There was no association between BAL fluid pepsin concentrations and age, sex, body mass index z score, forced expiratory volume in 1 s or Pseudomonas aeruginosa colonisation status. CONCLUSIONS: Many children with CF have increased levels of pepsin in the BAL fluid compared with normal controls. Increased pepsin levels were associated with higher IL-8 concentrations in BAL fluid. These data suggest that aspiration of gastric contents occurs in a subset of patients with CF and is associated with more pronounced lung inflammation.
On the estimation of water pure compound parameters in association theories
DEFF Research Database (Denmark)
Grenner, Andreas; Kontogeorgis, Georgios; Michelsen, Michael Locht;
2007-01-01
Determination of the appropriate number of association sites and estimation of parameters for association (SAFT-type) theories is not a trivial matter. Building further on a recently published manuscript by Clark et al., this work investigates aspects of the parameter estimation for water using two...... different association theories. Their performance for various properties as well as against the results presented earlier is demonstrated....
Yu, Yang-Xin
2009-07-14
A novel weighted density functional theory (WDFT) for an inhomogeneous 12-6 Lennard-Jones fluid is proposed based on the modified fundamental measure theory for repulsive contribution, the mean-field approximation for attractive contribution, and the first-order mean-spherical approximation with a weighted density for correlation contribution. Extensive comparisons of the theoretical results with molecular simulation and experimental data indicate that the new WDFT yields accurate density profiles, adsorption isotherms, fluid-solid interfacial tensions, as well as disjoining potentials and pressures of simple gases such as argon, nitrogen, methane, ethane, and neon confined in slitlike pores or near graphitic solid surfaces. The present WDFT performs better than the nonlocal density functional theory, which is frequently used in the study of adsorption on porous materials. Since the proposed theory possesses a good dimensional crossover and is able to correctly reduce to two-dimensional case, it performs very well even in very narrow pores. In addition, the present WDFT reproduces very well the supercritical fluid-solid interfacial tensions, whereas the theory of Sweatman underestimates them at high bulk densities. The present WDFT predicts that the increase in the fluid-wall attraction may change the sign of the interfacial tension and hence may make the wall from "phobic" to "philic" with respect to the fluid. The new WDFT is computationally as simple and efficient as the mean-field theory and avoids the second-order direct correlation function as an input. It provides a universal way to construct the excess Helmholtz free-energy functional for inhomogeneous fluids such as Yukawa, square-well, and Sutherland fluids.
A Rare Case of Spontaneous Pneumocephalus Associated with Nontraumatic Cerebrospinal Fluid Leak
Directory of Open Access Journals (Sweden)
Murad Baba
2016-01-01
Full Text Available Introduction. Spontaneous nontraumatic pneumocephalus (PNC and cerebrospinal fluid (CSF leaks are both very uncommon conditions. We report a rare case of spontaneous pneumocephalus associated with CSF leak secondary to right sphenoid sinus bony defect without history of trauma. Case Description. 51-year-old Hispanic female with past medical history of hypertension and idiopathic intracranial hypertension (Pseudotumor Cerebri presented to the emergency room complaining of headache and clear discharge from the right nostril. Physical examination was significant for right frontal sinus tenderness and clear discharge from right nostril. Computed Tomography (CT scan of the brain showed moderate amount of extra-axial air within the right cerebral hemisphere indicative of pneumocephalus. CT scan of facial bones showed bony defect along the right sphenoid sinus with abnormal CSF collection. The patient was started on intravenous antibiotics for meningitis prophylaxis and subsequently underwent transsphenoidal repair of cerebrospinal fluid leak with abdominal fat graft. CSF rhinorrhea stopped completely after the surgery with near complete resolution of pneumocephalus before discharge. Conclusions. Early identification of pneumocephalus and surgical intervention can help decrease the morbidity and avoid possible complications. Idiopathic intracranial hypertension, although rare, can lead to CSF leak and pneumocepahlus.
Mathematical Models of Fluid Dynamics Modeling, Theory, Basic Numerical Facts An Introduction
Ansorge, Rainer
2009-01-01
Without sacrificing scientific strictness, this introduction to the field guides readers through mathematical modeling, the theoretical treatment of the underlying physical laws and the construction and effective use of numerical procedures to describe the behavior of the dynamics of physical flow. The book is carefully divided into three main parts:. - The design of mathematical models of physical fluid flow;. - A theoretical treatment of the equations representing the model, as Navier-Stokes, Euler, and boundary layer equations, models of turbulence, in order to gain qualitative as well as q
Zimdahl, W; Zimdahl, Winfried; Balakin, Alexander B.
1998-01-01
The particles of a classical relativistic gas are supposed to move under the influence of a quasilinear (in the particle four-momenta), self-interacting force inbetween elastic, binary collisions. This force which is completely fixed by the equilibrium conditions of the gas, gives rise to an effective viscous pressure on the fluid phenomenological level. Earlier results concerning the possibility of accelerated expansion of the universe due to cosmological particle production are reinterpreted. A phenomenon such as power law inflation may be traced back to specific self-interacting forces keeping the particles of a gas universe in states of generalized equilibrium.
Theory and simulation of time-fractional fluid diffusion in porous media
Carcione, José M.; Sanchez-Sesma, Francisco J.; Luzón, Francisco; Perez Gavilán, Juan J.
2013-08-01
We simulate a fluid flow in inhomogeneous anisotropic porous media using a time-fractional diffusion equation and the staggered Fourier pseudospectral method to compute the spatial derivatives. A fractional derivative of the order of 0 classical diffusion equation. It implies a time-dependent permeability tensor having a power-law time dependence, which describes memory effects and accounts for anomalous diffusion. We provide a complete analysis of the physics based on plane waves. The concepts of phase, group and energy velocities are analyzed to describe the location of the diffusion front, and the attenuation and quality factors are obtained to quantify the amplitude decay. We also obtain the frequency-domain Green function. The time derivative is computed with the Grünwald-Letnikov summation, which is a finite-difference generalization of the standard finite-difference operator to derivatives of fractional order. The results match the analytical solution obtained from the Green function. An example of the pressure field generated by a fluid injection in a heterogeneous sandstone illustrates the performance of the algorithm for different values of ν. The calculation requires storing the whole pressure field in the computer memory since anomalous diffusion ‘recalls the past’.
Collapse and dispersal of a homogeneous spin fluid in Einstein-Cartan theory
Hashemi, M.; Jalalzadeh, S.; Ziaie, A. H.
2015-02-01
In the present work, we revisit the process of gravitational collapse of a spherically symmetric homogeneous dust fluid which is described by the Oppenheimer-Snyder (OS) model (Oppenheimer and Snyder in Phys Rev D 56:455, 1939). We show that such a scenario would not end in a spacetime singularity when the spin degrees of freedom of fermionic particles within the collapsing cloud are taken into account. To this purpose, we take the matter content of the stellar object as a homogeneous Weyssenhoff fluid. Employing the homogeneous and isotropic FLRW metric for the interior spacetime setup, it is shown that the spin of matter, in the context of a negative pressure, acts against the pull of gravity and decelerates the dynamical evolution of the collapse in its later stages. Our results show a picture of gravitational collapse in which the collapse process halts at a finite radius, whose value depends on the initial configuration. We thus show that the spacetime singularity that occurs in the OS model is replaced by a non-singular bounce beyond which the collapsing cloud re-expands to infinity. Depending on the model parameters, one can find a minimum value for the boundary of the collapsing cloud or correspondingly a threshold value for the mass content below which the horizon formation can be avoided. Our results are supported by a thorough numerical analysis.
Directory of Open Access Journals (Sweden)
M.Valiskó
2005-01-01
Full Text Available A systematic Monte Carlo (MC simulation and perturbation theoretical (PT study is reported for the dielectric constant of the polarizable dipolar hard sphere (PDHS fluid. We take the polarizability of the molecules into account in two different ways. In a continuum approach we place the permanent dipole of the molecule into a sphere of dielectric constant ε∞ in the spirit of Onsager. The high frequency dielectric constant ε∞ is calculated from the Clausius-Mosotti relation, while the dielectric constant of the polarizable fluid is obtained from the Kirkwood-Fröhlich equation. In the molecular approach, the polarizability is built into the model on the molecular level, which makes the interactions non-pairwise additive. Here we use Wertheim's renormalized PT method to calculate the induced dipole moment, while the dielectric constant is calculated from our recently introduced formula. We also apply a series expansion for the dielectric constant both in the continuum and the molecular approach. These series expansions ensure a better agreement with simulation results. The agreement between our MC data and the PT results in the molecular approach is excellent for low to moderate dipole moments and polarizabilities. At stronger dipolar interactions ergodicity problems and anizotropic behaviour appear where simulation results become uncertain and the theoretical approach becomes invalid.
2010-10-01
... 46 Shipping 2 2010-10-01 2010-10-01 false Main and auxiliary machinery and associated equipment... SECURITY (CONTINUED) MARINE ENGINEERING PERIODIC TESTS AND INSPECTIONS Periodic Tests of Machinery and Equipment § 61.20-3 Main and auxiliary machinery and associated equipment, including fluid control...
Bednarek, Tomasz; Tsotridis, Georgios
2017-03-01
The objective of the current study is to highlight possible limitations and difficulties associated with Computational Fluid Dynamics in PEM single fuel cell modelling. It is shown that an appropriate convergence methodology should be applied for steady-state solutions, due to inherent numerical instabilities. A single channel fuel cell model has been taken as numerical example. Results are evaluated for quantitative as well qualitative points of view. The contribution to the polarization curve of the different fuel cell components such as bi-polar plates, gas diffusion layers, catalyst layers and membrane was investigated via their effects on the overpotentials. Furthermore, the potential losses corresponding to reaction kinetics, due to ohmic and mas transport limitations and the effect of the exchange current density and open circuit voltage, were also investigated. It is highlighted that the lack of reliable and robust input data is one of the issues for obtaining accurate results.
Directory of Open Access Journals (Sweden)
Alborizi Abdolvahab
2009-06-01
Full Text Available We describe the development of enterovirus meningoencephalitis associated with increased adenosine deaminase in cerebrospinal fluid of a 12-year-old boy, a known case of hypogamaglobulinemia despite monthly replacement of IVIg.The patient was referred to our center with fever, headache and vomiting for 10 days. CSF analysis was compatible with aseptic meningoencephalitis but high CSF protein (>200mg/dl and high level of adenosine deaminase in CSF (30IU/L were against the diagnosis of simple viral meningoencephalitis. Nested PCR of CSF for entrovirus was positive. Treatment with daily high-dose IVIg was commenced, with significant clinical improvement. For patients with increased ADA and lymphocytic pleocytosis in CSF, differential diagnoses should include enteroviral meningitis. Antibodies, although crucial, cannot on their own prevent enteroviral infection in some hypogamaglbulinemic patients.
Hengartner, Michael P; Ajdacic-Gross, Vladeta; Rodgers, Stephanie; Müller, Mario; Haker, Helene; Rössler, Wulf
2014-08-01
There is some evidence that fluid intelligence as well as empathy may be significantly related to personality disorders (PDs). To our knowledge, no study has addressed those issues simultaneously in all 10 DSM PDs in a sample of the general population. We analysed data from 196 participants aged 20–41 from the Epidemiology Survey of the Zurich Programme for Sustainable Development of Mental Health Services (ZInEP), a comprehensive psychiatric survey in the general population of Zurich, Switzerland. We assessed the digit symbol-coding test (DSCT), the “reading the mind in the eyes” test (RMET) and the interpersonal reactivity index (IRI). Both measures of cognitive empathy (i.e. RMET and IRI perspective taking) were not related to any PD trait-score. The total PD trait-score was significantly associated with low scores on DSCT and IRI empathic concern and high scores on IRI personal distress, which indicates a dose–response relationship in those measures. DSCT was particularly related to borderline PD, IRI empathic concern to schizoid and narcissistic PDs, and IRI personal distress to avoidant PD. The proportion of variance explained in the total PD trait-score accounted for by DSCT, IRI empathic concern and IRI personal distress was 2.6, 2.3 and 13.3 %, respectively. Symptomatology and severity of PDs are related to low fluid intelligence and reduced emotional empathy as characterized by low empathic concern and high personal distress towards emotional expressions of others. Further research is needed that examines the association between cognitive empathy and personality pathology as well as potential clinical applications.
Hsiao, Shih-Ming; Tsai, Yi-Chun; Chen, Hui-Mei; Lin, Ming-Yen; Chiu, Yi-Wen; Chen, Tzu-Hui; Wang, Shu-Li; Hsiao, Pei-Ni; Kung, Lan-Fang; Hwang, Shang-Jyh; Huang, Mei-Feng; Yeh, Yi-Chun; Chen, Cheng-Sheng; Kuo, Mei-Chuan
2016-01-01
Background Impairment of physical function and abnormal body composition are the major presentations in patients with chronic kidney disease (CKD). The aim of this study is to investigate the relationship between body composition and physical function in CKD patients. Methods This cross-sectional study enrolled 172 of CKD stages 1–5 from February 2013 to September 2013. Handgrip strength (upper extremity muscle endurance), 30-second chair-stand test (lower extremity muscle endurance) and 2-minute step test (cardiorespiratory endurance) were used as indices of physical function. Body composition, including fluid status (extracellular water/total body water, ECW/TBW), lean tissue index (LTI), and fat tissue index (FTI), was measured using a bioimpedance spectroscopy method. Results All patients with high ECW/TBW had lower handgrip strength and 30-second chair-stand than those with low ECW/TBW (P<0.001 and P = 0.002). CKD patients with high FTI had lower handgrip strength and 30-second chair-stand than those with low FTI (P<0.001 and P = 0.002). These patients with low LTI had lower handgrip strength than those with high LTI (P = 0.04). In multivariate analysis, high ECW/TBW was positively associated with decreased handgrip strength (β = -41.17, P = 0.03) in CKD patients. High FTI was significantly correlated with decreased times of 30-second chair-stand (β = -0.13, P = 0.01). There was no significant relationship between body composition and 2-minute step test. Conclusions Our results show a significant association of impaired upper and lower extremity muscle endurance with high fluid status and fat tissue. Evaluation of body composition may assist in indentifying physical dysfunction earlier in CKD patients. PMID:27798648
Density-functional theory for fluid-solid and solid-solid phase transitions
Bharadwaj, Atul S.; Singh, Yashwant
2017-03-01
We develop a theory to describe solid-solid phase transitions. The density functional formalism of classical statistical mechanics is used to find an exact expression for the difference in the grand thermodynamic potentials of the two coexisting phases. The expression involves both the symmetry conserving and the symmetry broken parts of the direct pair correlation function. The theory is used to calculate phase diagram of systems of soft spheres interacting via inverse power potentials u (r ) =ɛ "close="1 /n )">σ /r n , where parameter n measures softness of the potential. We find that for 1 /n ≥0.154 the body-centred-cubic (bcc) structure is preferred. The bcc structure transforms into the fcc structure upon increasing the density. The calculated phase diagram is in good agreement with the one found from molecular simulations.
Selection principles and pattern formation in fluid mechanics and nonlinear shell theory
Sather, Duane P.
1987-01-01
Wave theories of vortex breakdown were studied. A setting which involved dynamical systems and bifurcations of homoclinic and heteroclinic orbits in infinite-dimensional spaces was investigated. The determination of axisymmetric inviscid flows bifurcating from the primary flow lead to the study of a system of ordinary differential equations. The problem of rotating plane Couette flow was solved by means of the structure parameter approach.
Starks, Erika J.; O'Grady, J. Patrick; Hoscheidt, Siobhan M.; Racine, Annie M.; Carlsson, Cindy M.; Zetterberg, Henrik; Blennow, Kaj; Okonkwo, Ozioma C.; Puglielli, Luigi; Asthana, Sanjay; Dowling, N. Maritza; Gleason, Carey E.; Anderson, Rozalyn M.; Davenport-Sis, Nancy J.; DeRungs, LeAnn M.; Sager, Mark A.; Johnson, Sterling C.; Bendlin, Barbara B.
2015-01-01
Background Insulin resistance (IR) is linked with the occurrence of pathological features observed in Alzheimer's disease (AD), including neurofibrillary tangles and amyloid plaques. However, the extent to which IR is associated with AD pathology in the cognitively asymptomatic stages of preclinical AD remains unclear. Objective To determine the extent to which IR is linked with amyloid and tau pathology in late-middle-age. Method Cerebrospinal fluid (CSF) samples collected from 113 participants enrolled in the Wisconsin Registry for Alzheimer's Prevention study (mean age = 60.6 years), were assayed for AD-related markers of interest: Aβ42, P-Tau181, and T-Tau. IR was determined using the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). Linear regression was used to test the effect of IR, and APOE ε4, on tau and amyloid pathology. We hypothesized that greater IR would be associated with higher CSF P-Tau181 and T-Tau, and lower CSF Aβ42. Results No significant main effects of HOMA-IR on P-Tau181, T-Tau, or Aβ42 were observed; however, significant interactions were observed between HOMA-IR and APOE ε4 on CSF markers related to tau. Among APOE ε4 carriers, higher HOMA-IR was associated with higher P-Tau181 and T-Tau. Among APOE ε4 non-carriers, HOMA-IR was negatively associated with P-Tau181 and T-Tau. We found no effects of IR on Aβ42 levels in CSF. Conclusion IR among asymptomatic APOE ε4 carriers was associated with higher P-Tau181 and T-Tau in late-middle age. The results suggest that IR may contribute to tau-related neurodegeneration in preclinical AD. The findings may have implications for developing prevention strategies aimed at modifying IR in mid-life. PMID:25812851
Quan, W L; Chen, Q F; Fu, Z J; Sun, X W; Zheng, J; Gu, Y J
2015-02-01
A consistent theoretical model that can be applied in a wide range of densities and temperatures is necessary for understanding the variation of a material's properties during compression and heating. Taking argon as an example, we show that the combination of self-consistent fluid variational theory and linear response theory is a promising route for studying warm dense matter. Following this route, the compositions, equations of state, and transport properties of argon plasma are calculated in a wide range of densities (0.001-20 g/cm(3)) and temperatures (5-100 kK). The obtained equations of state and electrical conductivities are found in good agreement with available experimental data. The plasma phase transition of argon is observed at temperatures below 30 kK and density about 2-6g/cm(3). The minimum density for the metallization of argon is found to be about 5.8 g/cm(3), occurring at 30-40 kK. The effects of many-particle correlations and dynamic screening on the electrical conductivity are also discussed through the effective potentials.
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Carlos Cruchaga
2010-09-01
Full Text Available Alzheimer's Disease (AD is a complex and multifactorial disease. While large genome-wide association studies have had some success in identifying novel genetic risk factors for AD, case-control studies are less likely to uncover genetic factors that influence progression of disease. An alternative approach to identifying genetic risk for AD is the use of quantitative traits or endophenotypes. The use of endophenotypes has proven to be an effective strategy, implicating genetic risk factors in several diseases, including anemia, osteoporosis and heart disease. In this study we identify a genetic factor associated with the rate of decline in AD patients and present a methodology for identification of other such factors. We have used an established biomarker for AD, cerebrospinal fluid (CSF tau phosphorylated at threonine 181 (ptau(181 levels as an endophenotype for AD, identifying a SNP, rs1868402, in the gene encoding the regulatory sub-unit of protein phosphatase B, associated with CSF ptau(181 levels in two independent CSF series (P(combined = 1.17 x 10(-05. We show no association of rs1868402 with risk for AD or age at onset, but detected a very significant association with rate of progression of disease that is consistent in two independent series (P(combined = 1.17 x 10(-05. Our analyses suggest that genetic variants associated with CSF ptau(181 levels may have a greater impact on rate of progression, while genetic variants such as APOE4, that are associated with CSF Aβ(42 levels influence risk and onset but not the rate of progression. Our results also suggest that drugs that inhibit or decrease tau phosphorylation may slow cognitive decline in individuals with very mild dementia or delay the appearance of memory problems in elderly individuals with low CSF Aβ(42 levels. Finally, we believe genome-wide association studies of CSF tau/ptau(181 levels should identify novel genetic variants which will likely influence rate of progression of
Institute of Scientific and Technical Information of China (English)
YU Yang-Xin; WU Jian-Zhong; YOU Feng-Qi; GAO Guang-Hua
2005-01-01
@@ An extended test-particle method is used to predict the inter- and intramolecular correlation functions of freely jointed hard-sphere-Yukawa-chain fluids by calculating the segmental density distributions around a fixed seg ment. The underlying density functional theory for chain fluids is based on a modified fundamental measure theory for the hard-sphere repulsive and a mean-field approximation for attraction between different segments.The calculated intra- and inter-molecular distribution functions agree well with the results from Monte Carlo simulations, better than those from alternative approaches.
Stellwagen, Kurt K; Kerig, Patricia K
2013-10-01
This study examined the association of ringleader bullying with psychopathic traits and theory of mind among 100 youth aged 10-15 (62 boys and 38 girls) receiving inpatient psychiatric services at a state facility. Results of hierarchical multiple regression analyses indicated a positive association between ringleader bullying and psychopathic narcissism, and a significant interaction effect between narcissism and theory of mind. More specifically, narcissism moderated the relationship between theory of mind and ringleader bullying such that theory of mind was positively associated with ringleader bullying when levels of narcissism were high, and theory of mind was negatively associated ringleader bullying when levels of narcissism were low. The discussion of these results focuses on the importance of developing effective treatment techniques for youth whose bullying behavior is associated with narcissistic features and social acuity.
Fundamental measure theory for lattice fluids with hard-core interactions
Lafuente, Luis; Cuesta, José A.
2002-11-01
We present the extension of Rosenfeld's fundamental measure theory to lattice models by constructing a density functional for d-dimensional mixtures of parallel hard hypercubes on a simple hypercubic lattice. The one-dimensional case is exactly solvable and two cases must be distinguished: all the species with the same length parity (additive mixture), and arbitrary length parity (nonadditive mixture). To the best of our knowledge, this is the first time that the latter case has been considered. Based on the one-dimensional exact functional form, we propose the extension to higher dimensions by generalizing the zero-dimensional cavity method to lattice models. This assures the functional will have correct dimensional crossovers to any lower dimension, including the exact zero-dimensional limit. Some applications of the functional to particular systems are also shown.
Hydrodynamic theory of partially degenerate electron-hole fluids in semiconductors
Akbari-Moghanjoughi, M.; Eliasson, B.
2016-10-01
A quantum hydrodynamic theory for high-frequency electron-hole Langmuir and acoustic-like oscillations as well as static charge shielding effects in arbitrarily doped semiconductors is presented. The model includes kinetic corrections to the quantum statistical pressure and to the quantum Bohm potential for partially degenerate electrons and holes at finite temperatures. The holes contribute to the oscillations and screening effects in semiconductors in a similar manner as real particles. The dielectric functions are derived in the high-frequency limit for wave excitations and in the low-frequency limit for the study of static screening. The dispersion relation for the Langmuir and acoustic-like oscillations is examined for different parameters of doped silicon (Si). Some interesting properties and differences of electron hole dynamical behavior in N- and P-type Si are pointed out. Holes are also observed to enhance an attractive charge shielding effect when the semiconductor is highly acceptor-doped.
Cosmology in ghost-free bigravity theory with twin matter fluids: The origin of "dark matter"
Aoki, Katsuki
2013-01-01
We study dynamics of Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime based on the ghost-free bigravity theory. Assuming the coupling parameters guaranteeing the existence of de Sitter space as well as Minkowski spacetime, we find two stable attractors for spacetime with "twin" dust matter fields: One is de Sitter accelerating universe and the other is matter dominated universe. Although a considerable number of initial data leads to de Sitter universe, we also find matter dominated universe or spacetime with a future singularity for some initial data. The cosmic no-hair conjecture does not exactly hold, but the accelerating expansion can be found naturally. The $\\Lambda$-CDM model is obtained as an attractor. We also show that the dark matter component in the Friedmann equation, which originates from another twin matter, can be about 5 times larger than the baryonic matter, by choosing the appropriate coupling constants.
Free glycogen in vaginal fluids is associated with Lactobacillus colonization and low vaginal pH.
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Paria Mirmonsef
Full Text Available Lactobacillus dominates the lower genital tract microbiota of many women, producing a low vaginal pH, and is important for healthy pregnancy outcomes and protection against several sexually transmitted pathogens. Yet, factors that promote Lactobacillus remain poorly understood. We hypothesized that the amount of free glycogen in the lumen of the lower genital tract is an important determinant of Lactobacillus colonization and a low vaginal pH.Free glycogen in lavage samples was quantified. Pyrosequencing of the 16S rRNA gene was used to identify microbiota from 21 African American women collected over 8-11 years.Free glycogen levels varied greatly between women and even in the same woman. Samples with the highest free glycogen had a corresponding median genital pH that was significantly lower (pH 4.4 than those with low glycogen (pH 5.8; p<0.001. The fraction of the microbiota consisting of Lactobacillus was highest in samples with high glycogen versus those with low glycogen (median = 0.97 vs. 0.05, p<0.001. In multivariable analysis, having 1 vs. 0 male sexual partner in the past 6 months was negatively associated, while BMI ≥30 was positively associated with glycogen. High concentrations of glycogen corresponded to higher levels of L. crispatus and L. jensenii, but not L. iners.These findings show that free glycogen in genital fluid is associated with a genital microbiota dominated by Lactobacillus, suggesting glycogen is important for maintaining genital health. Treatments aimed at increasing genital free glycogen might impact Lactobacillus colonization.
Samuels, David C.; Kallianpur, Asha R.; Ellis, Ronald J.; Bush, William S.; Letendre, Scott; Franklin, Donald; Grant, Igor; Hulgan, Todd
2017-01-01
Background Mitochondrial DNA (mtDNA) haplogroups are ancestry-related patterns of single-nucleotide polymorphisms that are associated with differential mitochondrial function in model systems, neurodegenerative diseases in HIV-negative populations, and chronic complications of HIV infection, including neurocognitive impairment. We hypothesized that mtDNA haplogroups are associated with neuroinflammation in HIV-infected adults. Methods CNS HIV Antiretroviral Therapy Effects Research (CHARTER) is a US-based observational study of HIV-infected adults who underwent standardized neurocognitive assessments. Participants who consented to DNA collection underwent whole blood mtDNA sequencing, and a subset also underwent lumbar puncture. IL-6, IL-8, TNF-α (high-sensitivity), and IP-10 were measured in cerebrospinal fluid (CSF) by immunoassay. Multivariable regression of mtDNA haplogroups and log-transformed CSF biomarkers were stratified by genetic ancestry using whole-genome nuclear DNA genotyping (European [EA], African [AA], or Hispanic ancestry [HA]), and adjusted for age, sex, antiretroviral therapy (ART), detectable CSF HIV RNA, and CD4 nadir. A total of 384 participants had both CSF cytokine measures and genetic data (45% EA, 44% AA, 11% HA, 22% female, median age 43 years, 74% on ART). Results In analyses stratified by the 3 continental ancestry groups, no haplogroups were significantly associated with the 4 biomarkers. In the subgroup of participants with undetectable plasma HIV RNA on ART, European haplogroup H participants had significantly lower CSF TNF-α (P = 0.001). Conclusions Lower CSF TNF-α may indicate lower neuroinflammation in the haplogroup H participants with well-controlled HIV on ART.
Zitron, Renato; Wajsfeld, Tali; Klautau, Giselle Burlamaqui; da Silva, Cely Barreto; Nigro, Stanley; Mercadante, Marcelo Tomanik; Polesello, Giancarlo Cavalli; Cury, Ricardo de Paula Leite; Salles, Mauro Jose Costa
2016-03-01
Microbial identification of orthopedic implant-associated infections using sonication fluid (SF) submitted to a concentration step by membrane filtration (SMF) was compared with the standard centrifugation (SC) method. Among 33 retrieved infected implants, sonication identified microorganisms in 26 (78.8%). The sensitivity of SC was higher than that of SMF (78.8% versus 30.3%; P < 0.001).
Dennesen, P.; Veerman, E.; Nieuw Amerongen, A. van; Jacobs, J.; Kessels, A.G.H.; Keijbus, P. van den; Ramsay, G.; Ven, A.J.A.M. van der
2003-01-01
OBJECTIVE: To compare the levels of sulfated mucins in bronchoalveolar lavage fluid (BALF) in ICU patients with ventilator-associated pneumonia (VAP) with those in non-infectious controls, i.e., ventilated ICU patients without VAP, and nonventilated patients. DESIGN AND SETTING: Prospective study in
Kvist, Ann Valentin; Gustafsson, Jan-Eric
2008-01-01
According to Cattell's [Cattell, R.B. (1987). "Intelligence: Its structure, growth and action." New York: North-Holland.] Investment theory individual differences in acquisition of knowledge and skills are partly the result of investment of Fluid Intelligence ("Gf") in learning situations demanding insights in complex…
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Heidi R. Flori
2011-01-01
Full Text Available Introduction. We analyzed a database of 320 pediatric patients with acute lung injury (ALI, to test the hypothesis that positive fluid balance is associated with worse clinical outcomes in children with ALI. Methods. This is a post-hoc analysis of previously collected data. Cumulative fluid balance was analyzed in ml per kilogram per day for the first 72 hours after ALI while in the PICU. The primary outcome was mortality; the secondary outcome was ventilator-free days. Results. Positive fluid balance (in increments of 10 mL/kg/24 h was associated with a significant increase in both mortality and prolonged duration of mechanical ventilation, independent of the presence of multiple organ system failure and the extent of oxygenation defect. These relationships remained unchanged when the subgroup of patients with septic shock (n=39 were excluded. Conclusions. Persistently positive fluid balance may be deleterious to pediatric patients with ALI. A confirmatory, prospective randomized controlled trial of fluid management in pediatric patients with ALI is warranted.
Reinstein, Eyal; Pariani, Mitchel; Bannykh, Serguei; Rimoin, David L; Schievink, Wouter I
2013-04-01
We aimed to assess the frequency of connective tissue abnormalities among patients with cerebrospinal fluid (CSF) leaks in a prospective study using a large cohort of patients. We enrolled a consecutive group of 50 patients, referred for consultation because of CSF leak. All patients have been carefully examined for the presence of connective tissue abnormalities, and based on findings, patients underwent genetic testing. Ancillary diagnostic studies included echocardiography, eye exam, and histopathological examinations of skin and dura biopsies in selected patients. We identified nine patients with heritable connective tissue disorders, including Marfan syndrome, Ehlers-Danlos syndrome and other unclassified forms. In seven patients, spontaneous CSF leak was the first noted manifestation of the genetic disorder. We conclude that spontaneous CSF leaks are associated with a spectrum of connective tissue abnormalities and may be the first noted clinical presentation of the genetic disorder. We propose that there is a clinical basis for considering spontaneous CSF leak as a clinical manifestation of heritable connective tissue disorders, and we suggest that patients with CSF leaks should be screened for connective tissue and vascular abnormalities.
Risk Associated With The Decompression Of High Pressure High Temperature Fluids - Study On Black Oil
DEFF Research Database (Denmark)
Figueroa, D. C.; Fosbøl, P. L.; Thomsen, K.
2015-01-01
Fluids produced from deep underground reservoirs may result in exponential increase in temperature. It is a consequence of adiabatic fluid decompression from the inverse Joule Thomson Effect (JTE). The phenomenon requires analysis in order to avoid any operational risks. This study evaluates...
General model of phospholipid bilayers in fluid phase within the single chain mean field theory
Energy Technology Data Exchange (ETDEWEB)
Guo, Yachong; Baulin, Vladimir A. [Departament d’Enginyeria Química, Universitat Rovira i Virgili, Av. dels Paisos Catalans 26, 43007 Tarragona (Spain); Pogodin, Sergey [Institute of Chemical Research of Catalonia, ICIQ, Av. Paisos Catalans 16, 43007 Tarragona (Spain)
2014-05-07
Coarse-grained model for saturated phospholipids: 1,2-didecanoyl-sn-glycero-3-phosphocholine (DCPC), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and unsaturated phospholipids: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1,2- dioleoyl-sn-glycero-3-phosphocholine (DOPC) is introduced within the single chain mean field theory. A single set of parameters adjusted for DMPC bilayers gives an adequate description of equilibrium and mechanical properties of a range of saturated lipid molecules that differ only in length of their hydrophobic tails and unsaturated (POPC, DOPC) phospholipids which have double bonds in the tails. A double bond is modeled with a fixed angle of 120°, while the rest of the parameters are kept the same as saturated lipids. The thickness of the bilayer and its hydrophobic core, the compressibility, and the equilibrium area per lipid correspond to experimentally measured values for each lipid, changing linearly with the length of the tail. The model for unsaturated phospholipids also fetches main thermodynamical properties of the bilayers. This model is used for an accurate estimation of the free energies of the compressed or stretched bilayers in stacks or multilayers and gives reasonable estimates for free energies. The proposed model may further be used for studies of mixtures of lipids, small molecule inclusions, interactions of bilayers with embedded proteins.
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Reiner Jumpertz
Full Text Available Rodent experiments have emphasized a role of central fatty acid (FA species, such as oleic acid, in regulating peripheral glucose and energy metabolism. Thus, we hypothesized that central FAs are related to peripheral glucose regulation and energy expenditure in humans. To test this we measured FA species profiles in cerebrospinal fluid (CSF and plasma of 32 individuals who stayed in our clinical inpatient unit for 6 days. Body composition was measured by dual energy X-ray absorptiometry and glucose regulation by an oral glucose test (OGTT followed by measurements of 24 hour (24EE and sleep energy expenditure (SLEEP as well as respiratory quotient (RQ in a respiratory chamber. CSF was obtained via lumbar punctures; FA concentrations were measured by liquid chromatography/mass spectrometry. As expected, FA concentrations were higher in plasma compared to CSF. Individuals with high concentrations of CSF very-long-chain saturated FAs had lower rates of SLEEP. In the plasma moderate associations of these FAs with higher 24EE were observed. Moreover, CSF monounsaturated long-chain FA (palmitoleic and oleic acid concentrations were associated with lower RQs and lower glucose area under the curve during the OGTT. Thus, FAs in the CSF strongly correlated with peripheral metabolic traits. These physiological parameters were most specific to long-chain monounsaturated (C16:1, C18:1 and very-long-chain saturated (C24:0, C26:0 FAs.Together with previous animal experiments these initial cross-sectional human data indicate that central FA species are linked to peripheral glucose and energy homeostasis.
LENUS (Irish Health Repository)
McNally, P
2011-02-01
Gastro-oesophageal reflux is common in children with cystic fibrosis (CF) and is thought to be associated with pulmonary aspiration of gastric contents. The measurement of pepsin in bronchoalveolar lavage (BAL) fluid has recently been suggested to be a reliable indicator of aspiration. The prevalence of pulmonary aspiration in a group of children with CF was assessed and its association with lung inflammation investigated.
Association of Brucella Meningoencephalitis with Cerebrospinal Fluid Shunt in A Child: A Case Report
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Babak ABDINIA
2013-02-01
Full Text Available How to Cite This Article: Abdinia B, Barzegar M, Maleki M, Behbod H, Oskoui Sh. Association of Brucella Meningoencephalitis with Cerebrospinal Fluid Shunt in a Child: a Case Report. Iran J Child Neurol. 2013 Winter:7(1:35-38. Brucellosis is an endemic zoonosis in Iran. It is a systemic infection that can involve any organs or systems of the body and have variable presentations. Ventriculoperitoneal (VP shunt infections due to brucellosis have been rarely reported in the literatures.This is the history of a four years old boy who developed Brucella meningoencephalitis at the age of 42 months, whilst he had a VP shunt in situ for hydrocephalus treatment. Also, he presented brucellosis as acute abdomen. This patient was treated with trimethoprim-sulfamethoxazole, gentamicin and rifampicin. The shunt was extracted and all clinical and laboratory test abnormalities subsided through this management.We propose that in a patient with Brucella meningoencephalitis, the cerebrospinal fluid shunt system can be extracted and treatment with appropriate combination of antibiotics could be successful. Moreover, it shows that brucellosis should be considered in the differential diagnosis for acute abdomen and ascites in endemic regions.References1. Hasanjani Roushan MR, Mohrez M, Samilnejad Gangi SM, Soleimani Amiri MJ, Hajiahmadi M. Epidemiological features and clinical manifestations in 469 adult patients with brucellosis in babol, Northern Iran. Epidemiol infect 2004;132(6:1109-142. Bouza E, García de la Torre M, Parras F, Guerrero A, Rodríguez-Créixems M, Gobernado J. Brucellar meningitis. Brucellar meningitis. Rev Infect Dis 1987; 9(4:810-22.3. Young EJ. Brucella species. In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas and Bennetts Õs Principles and Practice of Infectious Diseases. 5th ed. New York: Churchill Livingstone; 2000. p. 86-93.4. Feiz J, Sabbaghian H, Miralai M. Brucellosis due to Brucella
Thermophysical Properties of Fluids and Fluid Mixtures
Energy Technology Data Exchange (ETDEWEB)
Sengers, Jan V.; Anisimov, Mikhail A.
2004-05-03
The major goal of the project was to study the effect of critical fluctuations on the thermophysical properties and phase behavior of fluids and fluid mixtures. Long-range fluctuations appear because of the presence of critical phase transitions. A global theory of critical fluctuations was developed and applied to represent thermodynamic properties and transport properties of molecular fluids and fluid mixtures. In the second phase of the project, the theory was extended to deal with critical fluctuations in complex fluids such as polymer solutions and electrolyte solutions. The theoretical predictions have been confirmed by computer simulations and by light-scattering experiments. Fluctuations in fluids in nonequilibrium states have also been investigated.
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Wrensch Margaret
2006-10-01
Full Text Available Abstract Background The search for biologic endpoints and biomarkers in the study of breast cancer risk assessment and risk reduction strategies has led to an interest in obtaining cytologic information and other biomarkers from nipple aspirate fluid (NAF. Methods This descriptive study examined factors associated with an increased ability to obtain NAF in a cohort of 3043 women between the ages of 15 and 89 years of age. The majority of women were between the ages of 30–49 (N = 1529/50.2%. Variables examined in relation to obtaining fluid include: age, marital status, age at menarche, menopausal status, a history of pregnancy, a history of breast-feeding, estrogen use, oral contraceptive use, endocrine disorders and tranquilizer use. Results On average, women from whom breast fluid was obtained were younger than women from whom breast fluid was attempted but not obtained (mean = 41.9 years versus 46.5 years, p Conclusion Four variables (being married, history of pregnancy, tranquilizer use and endocrine disorders remained positively associated with the ability to obtain NAF in all analyses. A younger age was consistently associated with a greater ability to obtain NAF in this and other studies.
Institute of Scientific and Technical Information of China (English)
WANG Haijun; HONG Xiaozhong; GU Fang; BA Xinwu
2006-01-01
The influence of hydrogen bonds on the physical and chemical properties of hydrogen bonding fluid system of AaDd type is investigated from two viewpoints by the principle of statistical mechanics. In detail, we proposed two new ways that can be used to obtain the equilibrium size distribution of the hydrogen bonding clusters, and derived the analytical expression of a relationship between the hydrogen bonding free energy and hydrogen bonding degree. For the nonlinear hydrogen bonding systems, it is shown that the sol-gel phase transition can take place under proper conditions, which is further proven to be a kind of geometrical phase transition rather than a thermodynamic one. Moreover, several problems associated with the geometrical phase transition and liquid-solid phase transition in nonlinear hydrogen bonding systems are discussed.
Risk factors associated with uterine fluid after breeding caused by Streptococcus zooepidemicus.
Christoffersen, Mette; Söderlind, Maja; Rudefalk, Sofia Rydemann; Pedersen, Hanne Gervi; Allen, Joanne; Krekeler, Natali
2015-11-01
Infectious endometritis is a major cause of infertility in the mare and inflicts major losses on the equine breeding industry. The ability of the mare to eliminate uterine infections has been studied intensively for decades; however, despite identification of several factors contributing to the multifactorial pathogenesis and improved treatment, infectious endometritis remains a significant problem in a subpopulation of broodmares. Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is one of the most commonly isolated pathogens from the uterus of mares, suffering from infectious endometritis. Its ability to cause chronic latent infection by residing deep within the endometrial tissue has previously been described. The aim of the present study was to correlate different mare risk factors to infectious endometritis and pregnancy rates in broodmares and to investigate whether clonal or genetically distinct S. zooepidemicus strains isolated from mares with endometritis were associated with mare risk factors and the outcome of insemination. Mares (N = 152) were examined after natural cover, and 20% (31 mares) had intrauterine fluid (IUF) accumulation. Fifty-five percent (16 of 29) of the mares with IUF had infectious endometritis, and S. zooepidemicus was isolated in 81% (13 of 16) of these mares. Significantly more resting mares had IUF compared with foaling mares, and the foaling mares had the highest prevalence of positive bacterial growth from the uterine swab. The per-cycle pregnancy rate for the study was 63%. Pregnancy rate was significantly negatively affected by increased age (>12 years) and increased parity (>4), and the lowest pregnancy rate was observed in resting mares compared with foaling, barren, and maiden mares. Up to four S. zooepidemicus isolates were selected from each mare with growth of S. zooepidemicus from the uterine swab sample and further characterized by pulsed-field gel electrophoresis. In total, S. zooepidemicus isolates from
Workshop on Non-Associative & Non-Commutative Algebra and Operator Theory
Molina, Mercedes
2016-01-01
Presenting the collaborations of over thirty international experts in the latest developments in pure and applied mathematics, this volume serves as an anthology of research with a common basis in algebra, functional analysis and their applications. Special attention is devoted to non-commutative algebras, non-associative algebras, operator theory and ring and module theory. These themes are relevant in research and development in coding theory, cryptography and quantum mechanics. The topics in this volume were presented at the Workshop on Non-Associative & Non-Commutative Algebra and Operator Theory, held May 23—25, 2014 at Cheikh Anta Diop University in Dakar, Senegal in honor of Professor Amin Kaidi. The workshop was hosted by the university's Laboratory of Algebra, Cryptology, Algebraic Geometry and Applications, in cooperation with the University of Almería and the University of Málaga. Dr. Kaidi's work focuses on non-associative rings and algebras, operator theory and functional analysis, and he...
Longitudinal Associations between Children’s Understanding of Emotions and Theory of Mind
O’Brien, Marion; Weaver, Jennifer Miner; Nelson, Jackie A.; Calkins, Susan; Leerkes, Esther; Marcovitch, Stuart
2011-01-01
Theory of mind competence and knowledge of emotions were studied longitudinally in a sample of preschoolers aged 3 (n =263) and 4 (n =244) years. Children were assessed using standard measures of theory of mind and emotion knowledge. Three competing hypotheses were tested regarding the developmental associations between children’s theory of mind abilities and their knowledge of emotions. First, that an understanding of emotion develops early and informs children’s understanding of others’ thi...
Play and Theory of Mind: Associations with Social Competence in Young Children
Newton, Emma; Jenvey, Vickii
2011-01-01
This study aimed to investigate whether: (1) the development of "theory of mind" (ToM) is associated with social competence; and (2) social peer play is also associated with social competence in young children. Associations between ToM task performance, frequencies of observed social and solitary free-play and parent-rated social…
Directory of Open Access Journals (Sweden)
D. Schertzer
1996-01-01
. It had an appropriate editorial structure, in particular a large number of editors covering a wide range of methodologies, expertises and schools. At least two of its sections (Scaling and Multifractals, Turbulence and Diffusion were directly related to the topics of the workshop, in any case contributors were invited to choose their editor freely. 2 Goals of the Workshop The objective of this meeting was to enhance the confrontation between turbulence theories and empirical data from geophysics and astrophysics fluids with very high Reynolds numbers. The importance of these data seems to have often been underestimated for the evaluation of theories of fully developed turbulence, presumably due to the fact that turbulence does not appear as pure as in laboratory experiments. However, they have the great advantage of giving access not only to very high Reynolds numbers (e.g. 1012 for atmospheric data, but also to very large data sets. It was intended to: (i provide an overview of the diversity of potentially available data, as well as the necessary theoretical and statistical developments for a better use of these data (e.g. treatment of anisotropy, role of processes which induce other nonlinearities such as thermal instability, effect of magnetic field and compressibility ... , (ii evaluate the means of discriminating between different theories (e.g. multifractal intermittency models or to better appreciate the relevance of different notions (e.g. Self-Organized Criticality or phenomenology (e.g. filaments, structures, (iii emphasise the different obstacles, such as the ubiquity of catastrophic events, which could be overcome in the various concerned disciplines, thanks to theoretical advances achieved. 3 Outlines of the Workshop During the two days of the workshop, the series of presentations covered many manifestations of turbulence in geophysics, including: oceans, troposphere, stratosphere, very high atmosphere, solar wind, giant planets, interstellar clouds
Kou, Jisheng
2015-08-01
Surface tension significantly impacts subsurface flow and transport, and it is the main cause of capillary effect, a major immiscible two-phase flow mechanism for systems with a strong wettability preference. In this paper, we consider the numerical simulation of the surface tension of multi-component mixtures with the gradient theory of fluid interfaces. Major numerical challenges include that the system of the Euler-Lagrange equations is solved on the infinite interval and the coefficient matrix is not positive definite. We construct a linear transformation to reduce the Euler-Lagrange equations, and naturally introduce a path function, which is proven to be a monotonic function of the spatial coordinate variable. By using the linear transformation and the path function, we overcome the above difficulties and develop the efficient methods for calculating the interface and its interior compositions. Moreover, the computation of the surface tension is also simplified. The proposed methods do not need to solve the differential equation system, and they are easy to be implemented in practical applications. Numerical examples are tested to verify the efficiency of the proposed methods. © 2014 Elsevier B.V.
Institute of Scientific and Technical Information of China (English)
付东
2004-01-01
An analytical equation of state (EOS) for hard core Asakura-Oosawa (AO) fluid is established by combining the AO potential, the first-order perturbation theory and the radial distribution function (RDF) for the hard sphere fluid. The phase equilibria are studied by using the renormalization-group (RG) theory. The obtained results agree well with the simulation data. Investigation shows that the attractive range parameter plays an important role in the phase equilibria for AO fluid.
Associative nature of event participation dynamics: a network theory approach
Smiljanić, Jelena
2016-01-01
Affiliation with various social groups can be a critical factor when it comes to quality of life of every individual, making these groups an essential element of every society. The group dynamics, longevity and effectiveness strongly depend on group's ability to attract new members and keep them engaged in group activities. It was shown that high heterogeneity of scientist's engagement in conference activities of the specific scientific community depends on the balance between the number of previous attendance and non-attendance and is directly related to scientist's association with that community. Here we show that the same holds for leisure groups of Meetup website and further quantify member's association with the group. We examine how structure of personal social networks is evolving with event attendance. Our results show that member's increasing engagement in group activities is primarily associated with the strengthening of already existing ties and increase of bonding social capital. We also show tha...
Eto, Kumi; Koch, Pamela; Contento, Isobel R.; Adachi, Miyuki
2011-01-01
Objective: To examine associations between Theory of Planned Behavior variables and the family meal frequency. Methods: Fifth-through seventh-grade students (n = 236) completed a self-administered questionnaire in their classrooms. The relationships between Theory of Planned Behavior variables (intention, attitudes, subjective norms, and perceived…
Scholte, Johannes B J; van Dessel, Helke A; Linssen, Catharina F M; Bergmans, Dennis C J J; Savelkoul, Paul H M; Roekaerts, Paul M H J; van Mook, Walther N K A
2014-10-01
Authoritative guidelines state that the diagnosis of ventilator-associated pneumonia (VAP) can be established using either endotracheal aspirate (ETA) or bronchoalveolar lavage fluid (BALF) analysis, thereby suggesting that their results are considered to be in accordance. Therefore, the results of ETA Gram staining and semiquantitative cultures were compared to the results from a paired ETA-BALF analysis. Different thresholds for the positivity of ETAs were assessed. This was a prospective study of all patients who underwent bronchoalveolar lavage for suspected VAP in a 27-bed university intensive care unit during an 8-year period. VAP was diagnosed when ≥ 2% of the BALF cells contained intracellular organisms and/or when BALF quantitative culture revealed ≥ 10(4) CFU/ml of potentially pathogenic microorganisms. ETA Gram staining and semiquantitative cultures were compared to the results from paired BALF analysis by Cohen's kappa coefficients. VAP was suspected in 311 patients and diagnosed in 122 (39%) patients. In 288 (93%) patients, the results from the ETA analysis were available for comparison. Depending on the threshold used and the diagnostic modality, VAP incidences varied from 15% to 68%. For the diagnosis of VAP, the most accurate threshold for positivity of ETA semiquantitative cultures was moderate or heavy growth, whereas the optimal threshold for BALF Gram staining was ≥ 1 microorganisms per high power field. The Cohen's kappa coefficients were 0.22, 0.31, and 0.60 for ETA and paired BALF Gram stains, cultures, and BALF Gram stains, respectively. Since the ETA and BALF Gram stains and cultures agreed only fairly, they are probably not interchangeable for diagnosing VAP.
Maternal and fetal characteristics associated with meconium-stained amniotic fluid
DEFF Research Database (Denmark)
Balchin, Imelda; Whittaker, John C; Lamont, Ronald F;
2011-01-01
To estimate the rates of meconium-stained amniotic fluid (AF) and adverse outcome in relation to gestational age and racial group, and to investigate the predictors of meconium-stained AF.......To estimate the rates of meconium-stained amniotic fluid (AF) and adverse outcome in relation to gestational age and racial group, and to investigate the predictors of meconium-stained AF....
An Approach to Associative Retrieval through the Theory of Fuzzy Sets
Sachs, Wladimir
1976-01-01
The theory of fuzzy sets is used to provide a rigorous formulation of the problem of associative retrieval. This formulation suggests the idea of using fuzzy clustering to organize data for retrieval. (Author)
Sobkowicz, H M; Holy, J; Scott, G L
1990-07-01
The intercalated body is a newly discovered organelle in the inner and outer spiral sulcus cells of the mouse organ of Corti. The organelle was found in the cochleas of 14-day and older intact mice and in organs in culture of corresponding ages. The organelle consists of a stack of interconnected cisternae of endoplasmic reticulum and of membrane bound rodlets that are intercalated between, and run parallel to, the cisternae. The cisternal membranes are predominantly smooth, but some may display ribosomes. Most rodlets are from 1 to 2 microns long, about 0.1 micron wide, and contain electron dense material. Mitochondria are commonly associated with or incorporated into the organelle. Some electron micrographs suggest that the rodlets may originate from modified mitochondria. It is our impression that the formation of the organelle begins with the apposition of cisternae and mitochondria. Cisternal-associated mitochondria appear to constrict, elongate, and lose their inner membranes. In both the intact animal and in culture, the cells of the inner and outer spiral sulci display microvilli, apical junctional complexes, lateral intercellular spaces containing interdigitating cell processes, and appear to be involved in fluid formation. Moreover, in culture, the cells of inner and outer spiral sulci as well as some cells proliferating in the outgrowth zone participate in fluid formation, producing large fluid pockets. All these cells commonly contain intercalated bodies. It is possible that in the intact animal, as in culture, intercalated bodies may play a role in fluid regulation in the immediate vicinity of the hair cells.
DEFF Research Database (Denmark)
Iyer, Kishore R; Kunecki, Marek; Boullata, Joseph I
2017-01-01
BACKGROUND: In phase III clinical studies, treatment with teduglutide was associated with clinically meaningful reductions (≥20% from baseline) in parenteral support (PS; parenteral nutrition and/or intravenous fluids) requirements in adult patients with intestinal failure associated with short...
Lim, Lee Moay; Tsai, Ni-Chin; Lin, Ming-Yen; Hwang, Daw-Yang; Lin, Hugo You-Hsien; Lee, Jia-Jung; Hwang, Shang-Jyh; Hung, Chi-Chih; Chen, Hung-Chun
2016-01-01
Chronic kidney disease (CKD) is frequently complicated with hyponatremia, probably because of fluid overload or diuretic usage. Hyponatremia in CKD population is associated with increased mortality, but the effect on renal outcome was unknown. We investigated whether hyponatremia is associated with fluid status and is a prognostic indicator for adverse outcomes in a CKD cohort of 4,766 patients with 1,009 diuretic users. We found that diuretic users had worse clinical outcomes compared with diuretic non-users. Hyponatremia (serum sodium measured as total body water by bioimpedance analysis, in diuretic users, but not in diuretic non-users. Furthermore, in Cox survival analysis, hyponatremia was associated with an increased risk for renal replacement therapy (hazard ratio, 1.45; 95% CI, 1.13–1.85, P 141 mEq/L) was associated with an increased risk for all-cause mortality. Thus, hyponatremia is an indicator of fluid imbalance and also a prognostic factor for renal replacement therapy in CKD patients treated with diuretics. PMID:27841359
Directory of Open Access Journals (Sweden)
Magee G
2013-06-01
Full Text Available Glenn Magee,1 Art Zbrozek21Premier Research Services, Charlotte, NC, USA; 2CSL Behring, King of Prussia, PA, USABackground: Fluid overload, including transfusion-associated circulatory overload (TACO, is a serious complication of fresh frozen plasma (FFP transfusion. The incidence of fluid overload is underreported and its economic impact is unknown. An evaluation of fluid overload cases in US hospitals was performed to assess the impact of fluid overload on length and cost of hospital stay.Study design and methods: Retrospective analysis was performed using a clinical and economic database covering >600 US hospitals. Data were collected for all inpatients discharged during 2010 who received ≥1 unit FFP during hospitalization. Incidence of fluid overload was determined through International Classification of Diagnosis (ICD-9 codes. Multivariate regression analysis was performed for primary outcome measures: hospital length of stay (LOS and total hospital costs.Results: Data were analyzed for 129,839 FFP-transfused patients, of whom 4,138 (3.2% experienced fluid overload (including TACO. Multivariate analysis, adjusting for baseline characteristics, found that increased LOS and hospital costs were independently associated with fluid overload. Patients diagnosed with fluid overload had longer mean LOS (12.9 days versus 10.0 days; P < 0.001 and higher mean hospital cost per visit ($46,644 versus $32,582; P < 0.001 compared with patients without fluid overload.Conclusion: For a population of US inpatients who received FFP during hospitalization, fluid overload was associated with a 29% increase in LOS and a $14,062 increase in hospital costs per visit. These findings suggest that the incidence of fluid overload in the general population is greater than historically reported. A substantial economic burden may be associated with fluid overload in the US.Keywords: fresh frozen plasma, fluid overload, hospital costs, hypervolemia, length of stay
Associative nature of event participation dynamics: A network theory approach
Smiljanić, Jelena; Mitrović Dankulov, Marija
2017-01-01
The affiliation with various social groups can be a critical factor when it comes to quality of life of each individual, making such groups an essential element of every society. The group dynamics, longevity and effectiveness strongly depend on group’s ability to attract new members and keep them engaged in group activities. It was shown that high heterogeneity of scientist’s engagement in conference activities of the specific scientific community depends on the balance between the numbers of previous attendances and non-attendances and is directly related to scientist’s association with that community. Here we show that the same holds for leisure groups of the Meetup website and further quantify individual members’ association with the group. We examine how structure of personal social networks is evolving with the event attendance. Our results show that member’s increasing engagement in the group activities is primarily associated with the strengthening of already existing ties and increase in the bonding social capital. We also show that Meetup social networks mostly grow trough big events, while small events contribute to the groups cohesiveness. PMID:28166305
Eisenberg, Bob; Hyon, Yunkyong; Liu, Chun
2010-09-14
Ionic solutions are mixtures of interacting anions and cations. They hardly resemble dilute gases of uncharged noninteracting point particles described in elementary textbooks. Biological and electrochemical solutions have many components that interact strongly as they flow in concentrated environments near electrodes, ion channels, or active sites of enzymes. Interactions in concentrated environments help determine the characteristic properties of electrodes, enzymes, and ion channels. Flows are driven by a combination of electrical and chemical potentials that depend on the charges, concentrations, and sizes of all ions, not just the same type of ion. We use a variational method EnVarA (energy variational analysis) that combines Hamilton's least action and Rayleigh's dissipation principles to create a variational field theory that includes flow, friction, and complex structure with physical boundary conditions. EnVarA optimizes both the action integral functional of classical mechanics and the dissipation functional. These functionals can include entropy and dissipation as well as potential energy. The stationary point of the action is determined with respect to the trajectory of particles. The stationary point of the dissipation is determined with respect to rate functions (such as velocity). Both variations are written in one Eulerian (laboratory) framework. In variational analysis, an "extra layer" of mathematics is used to derive partial differential equations. Energies and dissipations of different components are combined in EnVarA and Euler-Lagrange equations are then derived. These partial differential equations are the unique consequence of the contributions of individual components. The form and parameters of the partial differential equations are determined by algebra without additional physical content or assumptions. The partial differential equations of mixtures automatically combine physical properties of individual (unmixed) components. If a new
Entropy in molecular association and folding: Theory and computation
Brady, Gerald Patrick, Jr.
1997-09-01
This thesis addresses two central questions regarding entropy changes in protein folding and molecular recognition: (1) Can the entropy of a system be decomposed into individual components arising from particular atomic groups or physical interactions? and (2) Can molecular association thermodynamics be reliably calculated using current computational methods? To address the first question, the statistical-mechanical justification for entropy decomposition is theoretically investigated via 'cumulant' and 'beta-derivative' expansions of the entropy. The cumulant expansion demonstrates that entropy components may indeed be meaningfully ascribed to particular groups or interactions, although these components are coupled both explicitly via cross-terms and implicitly through the Boltzmann factor. The beta-derivative expansion (βDE) is shown to yield a complete decomposition of entropy, in that, the total entropy is completely partitioned amongst the contributing groups or interactions, with no individually unattributable cross- terms remaining. The question of calculating molecular association thermodynamics is examined via computational analysis of binding and solvation in a model peptide system. In particular, the gas ←⇔ crystal ←⇔ solution phase equilibrium thermodynamics of cyclic di-glycine (cGG) and cyclic di- alanine (cAA) is computed using a variety of techniques, and the results are compared to experimental data. The calculated cGG gas-to-solution free energy and gas-to- crystal enthalpy agree very well with experimental values; however, the gas-to-crystal entropy is overestimated by 15 eu. Of particular note, a reliable value of 14 eu is obtained for the association entropy barrier to gas ⇒ crystal transfer, the unfavorable net result of exchanging translational and rotational freedom in the gas phase for vibrational motion in the crystal. A mean-field Einstein Model underestimates the vibrational entropy of the crystal by 15 eu and, thus, appears
The cerebrospinal fluid proteome in HIV infection: change associated with disease severity.
Energy Technology Data Exchange (ETDEWEB)
Angel, Thomas E.; Jacobs, Jon M.; Spudich, Serena S.; Gritsenko, Marina A.; Fuchs, Dietmar; Liegler, Teri; Zetterberg, Henrik; Camp, David G.; Price, Richard W.; Smith, Richard D.
2012-03-20
Central nervous system (CNS) infection is a constant feature of systemic HIV infection with a clinical spectrum that ranges from chronic asymptomatic infection to severe cognitive and motor dysfunction. Analysis of cerebrospinal fluid (CSF) has played an important part in defining the character of this evolving infection and response to treatment. To further characterize CNS HIV infection and its effects, we applied advanced high-throughput proteomic methods to CSF to identify novel proteins and their changes with disease progression and treatment. After establishing an accurate mass and time (AMT) tag database containing 23,141 AMT tags for CSF peptides, we analyzed 91 CSF samples by LC-MS from 12 HIV-uninfected and 14 HIV-infected subjects studied in the context of initiation of antiretroviral and correlated abundances of identified proteins (a) within and between subjects, (b) with all other proteins across the entire sample set, and (c) with 'external' CSF biomarkers of infection (HIV RNA), immune activation (neopterin) and neural injury (neurofilament light chain protein, NFL). We identified a mean of 2,333 +/- 328 (SD) peptides covering 307 +/-16 proteins in the 91 CSF sample set. Protein abundances differed both between and within subjects sampled at different time points and readily separated those with and without HIV infection. Proteins also showed inter-correlations across the sample set that were associated with biologically relevant dynamic processes. One-hundred and fifty proteins showed correlations with the external biomarkers. For example, using a threshold of cross correlation coefficient (Pearson's) {le}0.3 and {ge}0.3 for potentially meaningful relationships, a total of 99 proteins correlated with CSF neopterin (43 negative and 56 positive correlations) and related principally to neuronal plasticity and survival and to innate immunity. Pathway analysis defined several networks connecting the identified proteins, including one with
The cerebrospinal fluid proteome in HIV infection: change associated with disease severity
Directory of Open Access Journals (Sweden)
Angel Thomas E
2012-03-01
Full Text Available Abstract Background Central nervous system (CNS infection is a nearly universal feature of untreated systemic HIV infection with a clinical spectrum that ranges from chronic asymptomatic infection to severe cognitive and motor dysfunction. Analysis of cerebrospinal fluid (CSF has played an important part in defining the character of this evolving infection and response to treatment. To further characterize CNS HIV infection and its effects, we applied advanced high-throughput proteomic methods to CSF to identify novel proteins and their changes with disease progression and treatment. Results After establishing an accurate mass and time (AMT tag database containing 23,141 AMT tags for CSF peptides, we analyzed 91 CSF samples by LC-MS from 12 HIV-uninfected and 14 HIV-infected subjects studied in the context of initiation of antiretroviral therapy and correlated abundances of identified proteins a within and between subjects, b with all other proteins across the entire sample set, and c with "external" CSF biomarkers of infection (HIV RNA, immune activation (neopterin and neural injury (neurofilament light chain protein, NFL. We identified a mean of 2,333 +/- 328 (SD peptides covering 307 +/-16 proteins in the 91 CSF sample set. Protein abundances differed both between and within subjects sampled at different time points and readily separated those with and without HIV infection. Proteins also showed inter-correlations across the sample set that were associated with biologically relevant dynamic processes. One-hundred and fifty proteins showed correlations with the external biomarkers. For example, using a threshold of cross correlation coefficient (Pearson's ≤ -0.3 and ≥0.3 for potentially meaningful relationships, a total of 99 proteins correlated with CSF neopterin (43 negative and 56 positive correlations and related principally to neuronal plasticity and survival and to innate immunity. Pathway analysis defined several networks connecting
Energy Technology Data Exchange (ETDEWEB)
M. Fayek; P. Goodell; M. Ren; A. Simmons
2005-07-11
The Nopal I uranium (U) deposit, Pena Blanca District, Mexico, largely consists of secondary U{sup 6+} minerals, which occur within a breccia pipe mainly hosted by the 44 Ma Nopal and Colorados volcanic formations. These two units overly the Pozos conglomerate formation and Cretaceous limestone. Three new vertical diamond drill holes (DDHs) were recently drilled at Nopal I. DDH-PB1 with continuous core was drilled through the Nopal I deposit and two additional DDHs were drilled {approx}50 m on either side of the cored hole. These DDHs terminate 20 m below the current water table, thus allowing the detection of possible gradients in radionuclide contents resulting from transport from the overlying uranium deposit. Primary uraninite within the main ore body is rare and fine-grained ({approx}50 micrometers), thus making geochronology of the Nopal I deposit very difficult. Uranium, lead and oxygen isotopes can be used to study fluid-uraninite interaction, provided that the analyses are obtained on the micro-scale. Secondary ionization mass spectrometry (SIMS) permits in situ measurement of isotopic ratios with a spatial resolution on the scale of a few {micro}m. Preliminary U-Pb results show that uraninite from the main ore body gives an age of 32 {+-} 8 Ma, whereas uraninite from the uraniferous Pozos conglomerate that lies nearly 100 m below the main ore body and 25 meters above the water table, gives a U-Pb age that is <1 Ma. Oxygen isotopic analyses show that uraninite from the ore body has a {delta}{sup 18}O = -10.8{per_thousand}, whereas the uraninite within the Pozos conglomerate has a {delta}{sup 18}O = +1.5{per_thousand}. If it is assumed that both uraninites precipitated from meteoric water ({delta}{sup 18}O = -7{per_thousand}), then calculated precipitation temperatures are 55 C for the uraninite from the ore body and 20 C for uraninite hosted by the Pozos conglomerate. These temperatures are consistent with previous studies that calculated precipitation
Butler, William E; Atai, Nadia; Carter, Bob; Hochberg, Fred
2014-01-01
The Richard Floor Biorepository supports collaborative studies of extracellular vesicles (EVs) found in human fluids and tissue specimens. The current emphasis is on biomarkers for central nervous system neoplasms but its structure may serve as a template for collaborative EV translational studies in other fields. The informatic system provides specimen inventory tracking with bar codes assigned to specimens and containers and projects, is hosted on globalized cloud computing resources, and embeds a suite of shared documents, calendars, and video-conferencing features. Clinical data are recorded in relation to molecular EV attributes and may be tagged with terms drawn from a network of externally maintained ontologies thus offering expansion of the system as the field matures. We fashioned the graphical user interface (GUI) around a web-based data visualization package. This system is now in an early stage of deployment, mainly focused on specimen tracking and clinical, laboratory, and imaging data capture in support of studies to optimize detection and analysis of brain tumour-specific mutations. It currently includes 4,392 specimens drawn from 611 subjects, the majority with brain tumours. As EV science evolves, we plan biorepository changes which may reflect multi-institutional collaborations, proteomic interfaces, additional biofluids, changes in operating procedures and kits for specimen handling, novel procedures for detection of tumour-specific EVs, and for RNA extraction and changes in the taxonomy of EVs. We have used an ontology-driven data model and web-based architecture with a graph theory-driven GUI to accommodate and stimulate the semantic web of EV science.
Directory of Open Access Journals (Sweden)
Jacek Waniewski
2016-01-01
Full Text Available During peritoneal dialysis (PD, the peritoneal membrane undergoes ageing processes that affect its function. Here we analyzed associations of patient age and dialysis vintage with parameters of peritoneal transport of fluid and solutes, directly measured and estimated based on the pore model, for individual patients. Thirty-three patients (15 females; age 60 (21–87 years; median time on PD 19 (3–100 months underwent sequential peritoneal equilibration test. Dialysis vintage and patient age did not correlate. Estimation of parameters of the two-pore model of peritoneal transport was performed. The estimated fluid transport parameters, including hydraulic permeability (LpS, fraction of ultrasmall pores (αu, osmotic conductance for glucose (OCG, and peritoneal absorption, were generally independent of solute transport parameters (diffusive mass transport parameters. Fluid transport parameters correlated whereas transport parameters for small solutes and proteins did not correlate with dialysis vintage and patient age. Although LpS and OCG were lower for older patients and those with long dialysis vintage, αu was higher. Thus, fluid transport parameters—rather than solute transport parameters—are linked to dialysis vintage and patient age and should therefore be included when monitoring processes linked to ageing of the peritoneal membrane.
Waniewski, Jacek; Antosiewicz, Stefan; Baczynski, Daniel; Poleszczuk, Jan; Pietribiasi, Mauro; Lindholm, Bengt; Wankowicz, Zofia
2016-01-01
During peritoneal dialysis (PD), the peritoneal membrane undergoes ageing processes that affect its function. Here we analyzed associations of patient age and dialysis vintage with parameters of peritoneal transport of fluid and solutes, directly measured and estimated based on the pore model, for individual patients. Thirty-three patients (15 females; age 60 (21-87) years; median time on PD 19 (3-100) months) underwent sequential peritoneal equilibration test. Dialysis vintage and patient age did not correlate. Estimation of parameters of the two-pore model of peritoneal transport was performed. The estimated fluid transport parameters, including hydraulic permeability (LpS), fraction of ultrasmall pores (α u), osmotic conductance for glucose (OCG), and peritoneal absorption, were generally independent of solute transport parameters (diffusive mass transport parameters). Fluid transport parameters correlated whereas transport parameters for small solutes and proteins did not correlate with dialysis vintage and patient age. Although LpS and OCG were lower for older patients and those with long dialysis vintage, αu was higher. Thus, fluid transport parameters--rather than solute transport parameters--are linked to dialysis vintage and patient age and should therefore be included when monitoring processes linked to ageing of the peritoneal membrane.
Perez, R. J.; Boles, J. R.
2002-12-01
Magnitude of vertical fluid movement and rates of quartz cementation were studied in three cored intervals where reverse faults cut the Eocene Misoa Fm in the Maracaibo basin, Venezuela. The faults are flower type structures, with slips up to 500 meters, generated by an Eocene inversion of Cretaceous-Paleocene normal displacements. The fault zones extend 2.5 meters away from the slip surface and are characterized by extensive quartz and chert precipitation associated with microfractures and cataclasis. Kinetic modeling of quartz precipitation suggests that the rates of microfracture annealing may have been initially up to 0.25 moles/C, lasting approximately 1 my after faulting started (37.5 mya) and subsequently decreasing during uplifting to less than 0.05 moles/C. Kinetic modeling suggests that quartz cementation along these reverse faults may have occurred in short periods of time and at approximately the same or lower rates than intervals away from faults. Minimum vertical distance of fluid flow along one fault zone was calculated with two different approaches. The first method divides the thermal gradient present during faulting (obtained through a thermal reconstruction of the area) by a difference between the host rock maximum burial temperature and fault cements temperatures (obtained from fluid inclusions). The second method integrates an average-weight function of the thermal gradient along the unknown depth. Both methods suggest that hot fluids, present during cementation, ascended a minimum of 450 to 800 meter along the fault zone.
Frederick, Jennifer Mary
older than the host sediment. Old pore fluid age may reflect complex flow patterns, such a fluid focusing, which can cause significant lateral migration as well as regions where downward flow reverses direction and returns toward the seafloor. Longer pathlines can produce pore fluid ages much older than that expected with a one-dimensional compaction model. For steady-state models with geometry representative of Blake Ridge (USA), a well-studied hydrate province, pore fluid ages beneath regions of topography and within fractured zones can be up to 70 Ma old. Results suggest that the measurements of 129-I/127-I reflect a mixture of new and old pore fluid. However, old pore fluid need not originate at great depths. Methane within pore fluids can travel laterally several kilometers, implying an extensive source region around the deposit. Iodine age measurements support the existence of fluid focusing beneath regions of seafloor topography at Blake Ridge, and suggest that the methane source at Blake Ridge is likely shallow. The response of methane hydrate reservoirs to warming is poorly understood. The great depths may protect deep oceanic hydrates from climate change for the time being because transfer of heat by conduction is slow, but warming will eventually be felt albeit in the far future. On the other hand, unique permafrost-associated methane hydrate deposits exist at shallow depths within the sediments of the circum-Arctic continental shelves. Arctic hydrates are thought to be a relict of cold glacial periods, aggrading when sea levels are much lower and shelf sediments are exposed to freezing air temperatures. During interglacial periods, rising sea levels flood the shelf, bringing dramatic warming to the permafrost- and hydrate-bearing sediments. Permafrost-associated methane hydrate deposits have been responding to warming since the last glacial maximum ~18 kaBP as a consequence of these natural glacial cycles. This `experiment,' set into motion by nature itself
Zhen, Yaxin; Zhou, Lin
2017-03-01
Based on nonlocal strain gradient theory, wave propagation in fluid-conveying viscoelastic single-walled carbon nanotubes (SWCNTs) is studied in this paper. With consideration of thermal effect and surface effect, wave equation is derived for fluid-conveying viscoelastic SWCNTs under longitudinal magnetic field utilizing Euler-Bernoulli beam theory. The closed-form expressions are derived for the frequency and phase velocity of the wave motion. The influences of fluid flow velocity, structural damping coefficient, temperature change, magnetic flux and surface effect are discussed in detail. SWCNTs’ viscoelasticity reduces the wave frequency of the system and the influence gets remarkable with the increase of wave number. The fluid in SWCNTs decreases the frequency of wave propagation to a certain extent. The frequency (phase velocity) gets larger due to the existence of surface effect, especially when the diameters of SWCNTs and the wave number decrease. The wave frequency increases with the increase of the longitudinal magnetic field, while decreases with the increase of the temperature change. The results may be helpful for better understanding the potential applications of SWCNTs in nanotechnology.
Reciprocal Associations between Young Children's Developing Moral Judgments and Theory of Mind
Smetana, Judith G.; Jambon, Marc; Conry-Murray, Clare; Sturge-Apple, Melissa L.
2012-01-01
Associations between young children's developing theory of mind (ToM) and judgments of prototypical moral transgressions were examined 3 times across 1 year in 70 American middle class 2.5- to 4-year-olds. Separate path models controlling for cross-time stability in judgments, within-time associations, and children's age at Wave 1 indicated that…
Through the Lens of Theory: Perspectives on an International Library Association.
Knuth, Rebecca
1996-01-01
Discusses a study of the International Association of School Librarianship (IASL) with the goal of offering an alternative model for studying associations that combines a theoretical framework with a case study design. Theories of organization, convergence, and global integrity ethics are discussed, and a survey of IASL membership is appended.…
Solvation phenomena in association theories with applications to oil & gas and chemical industries
DEFF Research Database (Denmark)
Kontogeorgis, Georgios; Folas, Georgios; Muro Sunè, Nuria
2008-01-01
Association theories e.g. those belonging to the SAFT family account explicitly for self- and cross-association (solvation) phenomena. Such phenomena are of great practical importance as they affect, often dramatically, the phase behaviour of many mixtures of industrial relevance. From the scient...
Kohan, Donald E; Lambers Heerspink, Hiddo J; Coll, Blai; Andress, Dennis; Brennan, John J; Kitzman, Dalane W; Correa-Rotter, Ricardo; Makino, Hirofumi; Perkovic, Vlado; Hou, Fan Fan; Remuzzi, Giuseppe; Tobe, Sheldon W; Toto, Robert; Parving, Hans-Henrik; de Zeeuw, Dick
2015-01-01
BACKGROUND AND OBJECTIVES: Endothelin A receptor antagonists (ERAs) decrease residual albuminuria in patients with diabetic kidney disease; however, their clinical utility may be limited by fluid retention. Consequently, the primary objective of this study was to identify predictors for ERA-induced
The Alzheimer's Association external quality control program for cerebrospinal fluid biomarkers
Mattsson, N.; Andreasson, U.; Persson, S.; Arai, H.; Batish, S.D.; Bernardini, S.; Bocchio-Chiavetto, L.; Blankenstein, M.A.; Carrillo, M.C.; Chalbot, S.; Coart, E.; Chiasserini, D.; Cutler, N.; Dahlfors, G.; Duller, S.; Fagan, A.M.; Forlenza, O.; Frisoni, G.B.; Galasko, D.; Galimberti, D.; Hampel, H.; Handberg, A.; Heneka, M.T.; Herskovits, A.Z.; Herukka, S.K.; Holtzman, D.M.; Humpel, C.; Hyman, B.T.; Iqbal, K.; Jucker, M.; Kaeser, S.A.; Kaiser, E.; Kapaki, E.; Kidd, D.; Klivenyi, P.; Knudsen, C.S.; Kummer, M.P.; Lui, J.; Llado, A.; Lewczuk, P.; Li, Q.X.; Martins, R.; Masters, C.; McAuliffe, J.; Mercken, M.; Moghekar, A.; Molinuevo, J.L.; Montine, T.J.; Nowatzke, W.; O'Brien, R.; Otto, M.; Paraskevas, G.P.; Parnetti, L.; Petersen, R.C.; Prvulovic, D.; Reus, H.P. de; Rissman, R.A.; Scarpini, E.; Stefani, A.; Soininen, H.; Schroder, J.; Shaw, L.M.; Skinningsrud, A.; Skrogstad, B.; Spreer, A.; Talib, L.; Teunissen, C.; Trojanowski, J.Q.; Tumani, H.; Umek, R.M.; Broeck, B. Van; Vanderstichele, H.; Vecsei, L.; Verbeek, M.M.; Windisch, M.; Zhang, Jing; Zetterberg, H.; Blennow, K.
2011-01-01
BACKGROUND: The cerebrospinal fluid (CSF) biomarkers amyloid beta (Abeta)-42, total-tau (T-tau), and phosphorylated-tau (P-tau) demonstrate good diagnostic accuracy for Alzheimer's disease (AD). However, there are large variations in biomarker measurements between studies, and between and within lab
Zhang, Rui; Schweizer, Kenneth S
2012-04-21
We generalize the microscopic naïve mode coupling and nonlinear Langevin equation theories of the coupled translation-rotation dynamics of dense suspensions of uniaxial colloids to treat the effect of applied stress on shear elasticity, cooperative cage escape, structural relaxation, and dynamic and static yielding. The key concept is a stress-dependent dynamic free energy surface that quantifies the center-of-mass force and torque on a moving colloid. The consequences of variable particle aspect ratio and volume fraction, and the role of plastic versus double glasses, are established in the context of dense, glass-forming suspensions of hard-core dicolloids. For low aspect ratios, the theory provides a microscopic basis for the recently observed phenomenon of double yielding as a consequence of stress-driven sequential unlocking of caging constraints via reduction of the distinct entropic barriers associated with the rotational and translational degrees of freedom. The existence, and breadth in volume fraction, of the double yielding phenomena is predicted to generally depend on both the degree of particle anisotropy and experimental probing frequency, and as a consequence typically occurs only over a window of (high) volume fractions where there is strong decoupling of rotational and translational activated relaxation. At high enough concentrations, a return to single yielding is predicted. For large aspect ratio dicolloids, rotation and translation are always strongly coupled in the activated barrier hopping event, and hence for all stresses only a single yielding process is predicted.
Shaggy Photoreceptors with Subfoveal Fluid Associated with a Distant Choroidal Melanoma
Directory of Open Access Journals (Sweden)
Ann Q. Tran
2015-01-01
Full Text Available Purpose. To describe the enhanced depth imaging optical coherence tomography (EDI-OCT findings in a patient with an extra macula choroidal melanoma before and after treatment. Methods. Observational case report. Results. A 45 year-old Caucasian male patient was referred to retina clinic for management of choroidal melanoma. Examination revealed a nasal choroidal melanoma while EDI-OCT illustrated subfoveal fluid pocket with elongated shaggy photoreceptors distant and separate from the tumor. The patient was treated with plaque brachytherapy and intravitreal bevacizumab. One week after plaque removal, there was a dramatic reduction in the shaggy photoreceptors. Conclusion. Choroidal melanomas have effects that are not localized to the area of the tumor. This loculated pocket of subretinal fluid and coinciding changes to photoreceptor morphology may be related to global changes in choroidal function or release of tumor related cytokines.
A novel method for analyzing seismic energy loss associated with wave-induced fluid flow
Solazzi, Santiago G.; Germán Rubino, J.; Müller, Tobias M.; Milani, Marco; Guarracino, Luis; Holliger, Klaus
2014-05-01
Whenever a seismic wave propagates through a fluid saturated porous rock that contains heterogeneities in the mesoscopic scale, that is, heterogeneities larger than the typical pore size but smaller than the predominant wavelengths, local gradients in the pore-fluid pressure arise. These pressure gradients, which are due to the uneven response of the heterogeneities to the stress applied by the passing seismic wavefield, induce viscous fluid flow and energy dissipation. Consequently, seismic waves tend to be strongly attenuated and dispersed in this kind of media. This attenuation mechanism scales with the compressibility contrast between heterogeneities and the background. Correspondingly, environments characterized by patchy saturation as well as fractured media represent two prominent scenarios where seismic attenuation due to wave-induced fluid flow is expected to be the predominant energy dissipation mechanism. Numerical oscillatory compressibility and shear tests based on the quasistatic poroelasticity equations provide an effective means to compute equivalent viscoelastic moduli for representative rock samples of the heterogeneous media under study. Approaches of this type rely on the existence of a dynamic-equivalent medium, that is, the heterogeneous porous rock is represented by an equivalent homogeneous viscoelastic solid that exhibits an overall response similar to that of the original heterogeneous porous sample. This methodology allows for extracting the equivalent seismic attenuation and phase velocity of the sample, but fails to provide any information with regard to the underlying physical processes. In this work, we present a novel approach based on the quantification of the energy loss taking place in the interior of the considered heterogeneous rock sample. To this end, we first determine the spatial distribution of the energy dissipation in response to the applied oscillatory stresses. Next, we quantify the total dissipated energy as well as
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Hui Mao
2015-02-01
Full Text Available Micro-nano-based drilling fluid has attracted a strong interest due to its attractive properties, and micro-nano composite materials have great potential for developing intelligent drilling fluid. In this study a novel hydrophobic associated polymer based nano-silica composite with core–shell structure was prepared and characterized by PSD, SEM, TEM and ESEM. The results showed that the composite, as a micro-nano drilling fluid additive, possessed excellent properties such as thermal stability, rheology, fluid loss and lubricity. Especially, it could plug the formation effectively and improve the pressure bearing capability of formation significantly.
Liu, Chang
2015-01-01
The nonlinear frequency shift is derived in a transparent asymptotic form for intense Langmuir waves in general collisionless plasma. The formula describes both fluid and kinetic effects simultaneously. The fluid nonlinearity is expressed, for the ?first time, through the plasma dielectric function, and the kinetic nonlinearity accounts for both smooth distributions and trapped-particle beams. Various known limiting scalings are reproduced as special cases. The calculation avoids differential equations and can be extended straightforwardly to other nonlinear plasma waves.
Martin, E. Dale
1989-01-01
The paper introduces a new theory of N-dimensional complex variables and analytic functions which, for N greater than 2, is both a direct generalization and a close analog of the theory of ordinary complex variables. The algebra in the present theory is a commutative ring, not a field. Functions of a three-dimensional variable were defined and the definition of the derivative then led to analytic functions.
Theory of Fluids Penetrating Wood and Its Researching Method%木材流体渗透理论与研究方法
Institute of Scientific and Technical Information of China (English)
李永峰; 刘一星; 于海鹏; 刘镇波
2011-01-01
In order to know the present situation of research on theories of fluids penetrating wood overall and systematically, the paper presents a summary of the main styles and flowing theories of fluids in porous medium, the main penetrating channels of fluids in wood, and the main theories and experimental methods of research on fluids penetrating wood. Several major development directions of research on theories of fluids penetrating wood are also put forward.Advanced technologies are supposed to be adopted to observe dynamically during the whole continually process of liquids penetrating wood in the experimental observation on the research methods aspect, and more rational models of wood simple structure for fluids penetration, especially liquids penetration should also be established for exacting description on penetrating channels with less parameters. The mature theories and methods used in the heat and mass transfer, liquids permeability of construction material such as cement, stone and brick, soil and rock oil underground to establish the planar or three-dimensional theory model which conforms to the practical process of liquids penetrating wood unsteady are predicted in the theoretical studying. The two methods are suggested be combined to describe the mechanism of fluids penetrating wood qualitatively and quantitatively.%为较全面系统地了解木材流体渗透理论研究现状,从流体在多孔介质内的主要类型与流动理论、流体在木材内的主要流通通道及木材流体渗透性研究的主要理论与试验方法等几方面进行综合概述,提出木材流体渗透性理论研究的主要发展方向.试验观察应采取更先进的手段,动态观察流体尤其是液体渗透木材的整个连续过程,并构筑更合理的木材流体简化结构渗透模型,以较少的参数反映更完整的流体渗透途径;理论研究应借鉴木材干燥过程中应用较成熟的传质传热模型,建筑多孔材料如水泥、石、
Institute of Scientific and Technical Information of China (English)
Hun; Yong; SHIN; Hwayong; KIM; 等
2002-01-01
Quantitative representation of complicated behavior of fluid mixtures in the critical region by any of equation-of-state theories remains as a difficults thermodynamic topics to date.In the present work,a computational efforts were made for representing various types of critical loci of binary water with hydrocarbon systems showing Type Ⅱ and Type Ⅲ phase behavior by an elementary equation of state[called multi-fluid nonrandom lattice fluid EOS(MF-NLF EOS)]based on the lattice statistical mechanical theory.The model EOS requires two molecular parameters which representing molecular size and interaction energy for a pure component and single adjustable interaction energy parameter for binary mixtures.Critical temperature and pressure data were used to obtain molecular size parameter and vapor pressure data were used to obtain interaction energy parameter.The MF-NLF EOS model adapted in the present study correlated quantitatively well the critical loci of various binary water with hydrocarbon systems.
Tsiklauri, D
2001-01-01
It is known that a boundary slip velocity starts to play important role when the length scale over which the fluid velocity changes approaches the slip length, i.e. when the fluid is highly confined, for example, fluid flow through porous rock or blood vessel capillaries. Craig et al. [Phys. Rev. Lett., 87, 054504 (2001)] have recently experimentally established existence of a boundary slip in a Newtonian liquid. We investigate the effect of introduction of the boundary slip into the theory of propagation of elastic waves in a fluid-saturated porous medium formulated by Biot [J. Acoust. Soc. Am., 28, 179 (1956)]. Namely, we study the effect of introduction of boundary slip upon the function F(kappa) that measures the deviation from Poiseuille flow friction as a function of frequency parameter kappa. We found substantial deviations, especially in the asymptotical limit of high frequencies, in the behavior of F(kappa) with the incorporation of the boundary slip into the model. It is known that F(kappa) cruciall...
Hvozd, Taras V; Kalyuzhnyi, Yurij V
2017-02-15
We have studied the phase behavior of polydisperse Yukawa hard-sphere fluid confined in random porous media using extension and combination of high temperature approximation and scaled particle theory. The porous media are represented by the matrix of randomly placed hard-sphere obstacles. Due to the confinement, polydispersity effects are substantially enhanced. At an intermediate degree of fluid polydispersity and low density of the matrix, we observe two-phase coexistence with two critical points, and cloud and shadow curves forming closed loops of ellipsoidal shape. With the increase of the matrix density and the constant degree of polydispersity, these two critical points merge and disappear, and at lower temperatures the system fractionates into three coexisting phases. A similar phase behavior was observed in the absence of the porous media caused, however, by the increase of the polydispersity.
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Hugo TB
2014-08-01
Full Text Available Timothy B Hugo, Kathryn L Heading, Robert H Labuc Melbourne Veterinary Specialist Centre, Glen Waverley, Vic, Australia Introduction: The combination of cerebrospinal fluid (CSF analysis and magnetic resonance imaging (MRI are often used to investigate intracranial disease in dogs. The aim of this retrospective study was to determine if the total nucleated cell count (TNCC or cytology findings in abnormal CSF are associated with the prevalence of MRI abnormalities. Materials and methods: For each case, the TNCC was categorized into one of three groups: A (<25×106/L; B (25–100×106/L; and C (>100×106/L. Cytology findings were categorized by the predominant cell type as lymphocytic, monocytoid, neutrophilic, or eosinopilic. MRI descriptions were classified as either normal or abnormal, and abnormal studies were further evaluated for the presence of specific characteristics (multifocal or diffuse disease versus focal disease, positive T2-weighted hyperintensity, positive FLAIR hyperintensity, contrast enhancement, mass effect, and the presence of poorly or well-defined lesion margins. Results: Forty-five dogs met the inclusion criteria and MRI abnormalities were found in 29/45 (64% dogs. TNCCs were not associated with the prevalence of MRI abnormalities or specific characteristics. Cytology categories were significantly associated with the prevalence of MRI abnormalities (P<0.001. Specifically, monocytoid cytology was 22.8 times more likely to have an abnormal MRI than lymphocytic cytology. CSF cytology was not significantly associated with specific abnormal MRI characteristics. Conclusion: There are minimal associations between CSF abnormalities and the prevalence of MRI abnormalities. These results support the continued importance of utilizing both tests when investigating intracranial disease. When CSF analysis must be performed initially, this study has demonstrated that an abnormal CSF with a monocytoid cytology supports the value of
Association of Brucella Meningoencephalitis with Cerebrospinal Fluid Shunt in A Child: A Case Report
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Babak ABDINIA
2013-01-01
Full Text Available Brucellosis is an endemic zoonosis in Iran. It is a systemic infection that can involve any organs or systems of the body and have variable presentations. Ventriculoperitoneal (VP shunt infections due to brucellosis have been rarely reported in the literatures.This is the history of a four years old boy who developed Brucella meningoencephalitis at the age of 42 months, whilst he had a VP shunt in situ for hydrocephalus treatment. Also, he presented brucellosis as acute abdomen. This patient was treated with trimethoprim-sulfamethoxazole, gentamicin and rifampicin. The shunt was extracted and all clinical and laboratory test abnormalities subsided through this management.We propose that in a patient with Brucella meningoencephalitis, the cerebrospinal fluid shunt system can be extracted and treatment with appropriate combination of antibiotics could be successful. Moreover, it shows that brucellosis should be considered in the differential diagnosis for acute abdomen and ascites in endemic regions.
Evaluation of feasibility of measuring EHD film thickness associated with cryogenic fluids
Kannel, J. W.; Merriman, T. L.; Stockwell, R. D.; Dufrane, K. F.
1983-08-01
The feasibility of measuring elastohydrodynamic (EHD) films as formed with a cryogenic (LN2) fluid is evaluated. Modifications were made to an existing twin disk EHD apparatus to allow for disk lubrication with liquid nitrogen. This disk apparatus is equipped with an X-ray system for measuring the thickness of any lubricant film that is formed between the disks. Several film thickness experiments were conducted with the apparatus which indicate that good lubrication films are filmed with LN2. In addition to the film thickness studies, failure analyses of three bearings were conducted. The HPOTP turbine end bearings had experienced axial loads of 36,000 to 44,000 N (8,000 to 10,000 lb). High continuous radial loads were also experienced, which were most likely caused by thermal growth of the inner race. The resulting high internal loads caused race spalling and ball wear to occur.
Choquard, Philippe
2013-01-01
The coupling between dilatation and vorticity, two coexisting and fundamental processes in fluid dynamics is investigated here, in the simplest cases of inviscid 2D isotropic Burgers and pressureless Euler-Coriolis fluids respectively modeled by single vortices confined in compressible, local, inertial and global, rotating, environments. The field equations are established, inductively, starting from the equations of the characteristics solved with an initial Helmholtz decomposition of the velocity fields namely a vorticity free and a divergence free part and, deductively, by means of a canonical Hamiltonian Clebsch like formalism, implying two pairs of conjugate variables. Two vector valued fields are constants of the motion: the velocity field in the Burgers case and the momentum field per unit mass in the Euler-Coriolis one. Taking advantage of this property, a class of solutions for the mass densities of the fluids is given by the Jacobian of their sum with respect to the actual coordinates. Implementatio...
Genome-wide association study of NMDA receptor coagonists in human cerebrospinal fluid and plasma
Luykx, J. J.; Bakker, S. C.; Visser, W. F.; Verhoeven-Duif, N.; Buizer-Voskamp, J. E.; Den Heijer, J. M.; Boks, M. P. M.; Sul, J. H.; Eskin, E.; Ori, A. P.; Cantor, R. M.; Vorstman, J.; Strengman, E.; DeYoung, J.; Kappen, T. H.; Pariama, E.; van Dongen, E. P. A.; Borgdorff, P.; Bruins, P.; de Koning, T. J.; Kahn, R. S.; Ophoff, R. A.
2015-01-01
The N-methyl-D-aspartate receptor (NMDAR) coagonists glycine, D-serine and L-proline play crucial roles in NMDAR-dependent neurotransmission and are associated with a range of neuropsychiatric disorders. We conducted the first genome-wide association study of concentrations of these coagonists and t
Genome-wide association study of NMDA receptor coagonists in human cerebrospinal fluid and plasma
Luykx, J. J.; Bakker, S. C.; Visser, W. F.; Verhoeven-Duif, N.; Buizer-Voskamp, J. E.; den Heijer, J. M.; Boks, M. P M; Sul, J. H.; Eskin, E.; Ori, A. P.; Cantor, R. M.; Vorstman, J.; Strengman, E.; DeYoung, J.; Kappen, T. H.; Pariama, E.; van Dongen, E. P A; Borgdorff, P.; Bruins, P.; de Koning, T. J.; Kahn, R. S.; Ophoff, R. A.
2015-01-01
The N-methyl-d-aspartate receptor (NMDAR) coagonists glycine, d-serine and l-proline play crucial roles in NMDAR-dependent neurotransmission and are associated with a range of neuropsychiatric disorders. We conducted the first genome-wide association study of concentrations of these coagonists and t
Institute of Scientific and Technical Information of China (English)
吴畏; 陆九芳; 付东; 刘金晨; 李以圭
2004-01-01
The density functional theory, simplified by the local density approximation and mean-field approximation, is applied to study the surface properties of pure non-polar fluids. A reasonable long rang correction is adopted to avoid the truncation of the potential. The perturbation theory is applied to establish the equation for the phase equilibrium, in which the hard-core chain fluid is as the reference fluid and the Yukawa potential is used as the perturbation term. Three parameters, ε/k, d and ms, are regressed from the vapor-liquid equilibria, and the surface properties, including density profile, surface tension and local surface tension profile are predicted with these parameters.
Safonov, O.; Butvina, V.
2009-04-01
Relics of potassium-rich (4-14 wt. % of K2O and K2O/Na2O > 1.0) melts are a specific features of some partially molten diamondiferous eclogite xenoliths in kimberlites worldwide [1, 2]. In addition, potassic silicic melt inclusions with up to 16 wt. % of K2O are associated with eclogite phases in kimberlitic diamonds (O. Navon, pers. comm.). According to available experimental data, no such potassium contents can be reached by "dry" and hydrous melting of eclogite. These data point to close connection between infiltration of essentially potassic fluids, partial melting and diamond formation in mantle eclogites [2]. Among specific components of these fluids, alkali chlorides, apparently, play an important role. This conclusion follows from assemblages of the melt relics with chlorine-bearing phases in eclogite xenoliths [1], findings of KCl-rich inclusions in diamonds from the xenoliths [3], and concentration of Cl up to 0.5-1.5 wt. % in the melt inclusions in diamonds. In this presentation, we review our experimental data on reactions of KCl melts and KCl-bearing fluids with model and natural eclogite-related minerals and assemblages. Experiments in the model system jadeite(±diopside)-KCl(±H2O) at 4-7 GPa showed that, being immiscible, chloride liquids provoke a strong K-Na exchange with silicates (jadeite). As a result, low-temperature ultrapotassic chlorine-bearing (up to 3 wt. % of Cl) aluminosilicate melts form. These melts is able to produce sanidine, which is characteristic phase in some partially molten eclogites. In addition, in presence of water Si-rich Cl-bearing mica (Al-celadonite-phlogopite) crystallizes in equilibrium with sanidine and/or potassic melt and immiscible chloride liquid. This mica is similar to that observed in some eclogitic diamonds bearing chloride-rich fluid inclusions [4], as well as in diamonds in partially molten eclogites [2]. Interaction of KCl melt with pyrope garnet also produce potassic aluminosilicate melt because of high
Association between gingival crevicular fluid prostaglandin E 2 level and preterm low birth weight
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Fouzia Tarannum
2012-01-01
Conclusion: The study provides weak evidence that there is correlation between GCF-PGE 2 levels and birth outcome. Further clinical trials with large samples are required to confirm the association between GCF-PGE 2 levels and PLBW.
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Vinš Václav
2014-03-01
Full Text Available The density gradient theory (GT combined with a SAFT-type (Statistical Associating Fluid Theory equation of state has been used for modeling the surface tension of associating fluids represented by a series of six alkanols ranging from methanol to 1-pentanol. The effect of nonzero dipole moment of the selected alkanols on the predicted surface tension was investigated in this study. Results of the GT + non-polar Perturbed Chain (PC SAFT equation of state were compared to predictions of GT combined with the PC-polar-SAFT, i.e. PCP-SAFT, equation. Both GT + PC-SAFT and GT + PCP-SAFT give reasonable prediction of the surface tension for pure alkanols. Results of both models are comparable as no significant difference in the modeled saturation properties and in the predicted surface tension using GT was found. Consideration of dipolar molecules of selected alkanols using PCP-SAFT had only minor effect on the predicted properties compared to the non-polar PC-SAFT model.
De Houwer, Jan; Hughes, Sean; Barnes-Holmes, Dermot
2016-08-01
We aim to provide a new perspective on the old debate about whether evidence for higher order cognition in nonhuman animals can be reinterpreted in terms of associative learning. Our starting point is the idea that associative learning is best thought of as an effect (i.e., the impact of paired events on behavior) rather than a specific mental process (e.g., the formation of associations). This idea allows us to consider (a) propositional theories according to which associative learning is mediated by higher order mental processes akin to problem solving and (b) relational frame theory that allows one to think of seemingly simple associative learning effects as instances of a complex phenomenon known as arbitrarily applicable relational responding. Based on these 2 theories, we argue that (a) higher order cognition and associative learning are not necessarily mutually exclusive and (b) a more sophisticated conceptualization of higher order cognition is warranted. (PsycINFO Database Record
Malheiro, Carine; Mendiboure, Bruno; Plantier, Frédéric; Blas, Felipe J.; Miqueu, Christelle
2014-04-01
As a first step of an ongoing study of thermodynamic properties and adsorption of complex fluids in confined media, we present a new theoretical description for spherical monomers using the Statistical Associating Fluid Theory for potential of Variable Range (SAFT-VR) and a Non-Local Density Functional Theory (NLDFT) with Weighted Density Approximations (WDA). The well-known Modified Fundamental Measure Theory is used to describe the inhomogeneous hard-sphere contribution as a reference for the monomer and two WDA approaches are developed for the dispersive terms from the high-temperature Barker and Henderson perturbation expansion. The first approach extends the dispersive contributions using the scalar and vector weighted densities introduced in the Fundamental Measure Theory (FMT) and the second one uses a coarse-grained (CG) approach with a unique weighted density. To test the accuracy of this new NLDFT/SAFT-VR coupling, the two versions of the theoretical model are compared with Grand Canonical Monte Carlo (GCMC) molecular simulations using the same molecular model. Only the version with the "CG" approach for the dispersive terms provides results in excellent agreement with GCMC calculations in a wide range of conditions while the "FMT" extension version gives a good representation solely at low pressures. Hence, the "CG" version of the theoretical model is used to reproduce methane adsorption isotherms in a Carbon Molecular Sieve and compared with experimental data after a characterization of the material. The whole results show an excellent agreement between modeling and experiments. Thus, through a complete and consistent comparison both with molecular simulations and with experimental data, the NLDFT/SAFT-VR theory has been validated for the description of monomers.
Cattes, Stefanie M; Gubbins, Keith E; Schoen, Martin
2016-05-21
In this work, we employ classical density functional theory (DFT) to investigate for the first time equilibrium properties of a Heisenberg fluid confined to nanoscopic slit pores of variable width. Within DFT pair correlations are treated at modified mean-field level. We consider three types of walls: hard ones, where the fluid-wall potential becomes infinite upon molecular contact but vanishes otherwise, and hard walls with superimposed short-range attraction with and without explicit orientation dependence. To model the distance dependence of the attractions, we employ a Yukawa potential. The orientation dependence is realized through anchoring of molecules at the substrates, i.e., an energetic discrimination of specific molecular orientations. If the walls are hard or attractive without specific anchoring, the results are "quasi-bulk"-like in that they can be linked to a confinement-induced reduction of the bulk mean field. In these cases, the precise nature of the walls is completely irrelevant at coexistence. Only for specific anchoring nontrivial features arise, because then the fluid-wall interaction potential affects the orientation distribution function in a nontrivial way and thus appears explicitly in the Euler-Lagrange equations to be solved for minima of the grand potential of coexisting phases.
Cattes, Stefanie M.; Gubbins, Keith E.; Schoen, Martin
2016-05-01
In this work, we employ classical density functional theory (DFT) to investigate for the first time equilibrium properties of a Heisenberg fluid confined to nanoscopic slit pores of variable width. Within DFT pair correlations are treated at modified mean-field level. We consider three types of walls: hard ones, where the fluid-wall potential becomes infinite upon molecular contact but vanishes otherwise, and hard walls with superimposed short-range attraction with and without explicit orientation dependence. To model the distance dependence of the attractions, we employ a Yukawa potential. The orientation dependence is realized through anchoring of molecules at the substrates, i.e., an energetic discrimination of specific molecular orientations. If the walls are hard or attractive without specific anchoring, the results are "quasi-bulk"-like in that they can be linked to a confinement-induced reduction of the bulk mean field. In these cases, the precise nature of the walls is completely irrelevant at coexistence. Only for specific anchoring nontrivial features arise, because then the fluid-wall interaction potential affects the orientation distribution function in a nontrivial way and thus appears explicitly in the Euler-Lagrange equations to be solved for minima of the grand potential of coexisting phases.
An experimental study of the fluid mechanics associated with porous walls
Ramachandran, N.; Heaman, J.; Smith, A.
1992-01-01
The fluid mechanics of air exiting from a porous material is investigated. The experiments are filter rating dependent, as porous walls with filter ratings differing by about three orders of magnitude are studied. The flow behavior is investigated for its spatial and temporal stability. The results from the investigation are related to jet behavior in at least one of the following categories: (1) jet coalescence effects with increasing flow rate; (2) jet field decay with increasing distance from the porous wall; (3) jet field temporal turbulence characteristics; and (4) single jet turbulence characteristics. The measurements show that coalescence effects cause jet development, and this development stage can be traced by measuring the pseudoturbulence (spatial velocity variations) at any flow rate. The pseudoturbulence variation with increasing mass flow reveals an initial increasing trend followed by a leveling trend, both of which are directly proportional to the filter rating. A critical velocity begins this leveling trend and represents the onset of fully developed jetting action in the flow field. A correlation is developed to predict the onset of fully developed jets in the flow emerging from a porous wall. The data further show that the fully developed jet dimensions are independent of the filter rating, thus providing a length scale for this type of flow field (1 mm). Individual jet characteristics provide another unifying trend with similar velocity decay behavior with distance; however, the respective turbulence magnitudes show vast differences between jets from the same sample. Measurements of the flow decay with distance from the porous wall show that the higher spatial frequency components of the jet field dissipate faster than the lower frequency components. Flow turbulence intensity measurements show an out of phase behavior with the velocity field and are generally found to increase as the distance from the wall is increased.
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Bharti AR
2016-04-01
Full Text Available Ajay R Bharti,1 Steven Paul Woods,2 Ronald J Ellis,3 Mariana Cherner,2 Debra Rosario,3 Michael Potter,3 Robert K Heaton,2 Ian P Everall,4 Eliezer Masliah,5 Igor Grant,2 Scott L Letendre1 On behalf of the Translational Methamphetamine AIDS Research Center Group 1Department of Medicine, 2Department of Psychiatry, 3Department of Neurosciences, University of California San Diego, San Diego, CA, USA; 4Department of Psychiatry, University of Melbourne, Victoria, Australia; 5Department of Pathology, University of Californa San Diego, San Diego, CA, USA Background: Human immunodeficiency virus (HIV and methamphetamine use commonly affect neurocognitive (NC functioning. We evaluated the relationships between NC functioning and two fibroblast growth factors (FGFs in volunteers who differed in HIV serostatus and methamphetamine dependence (MAD. Methods: A total of 100 volunteers were categorized into four groups based on HIV serostatus and MAD in the prior year. FGF-1 and FGF-2 were measured in cerebrospinal fluid by enzyme-linked immunosorbent assays along with two reference biomarkers (monocyte chemotactic protein [MCP]-1 and neopterin. Comprehensive NC testing was summarized by global and domain impairment ratings. Results: Sixty-three volunteers were HIV+ and 59 had a history of MAD. FGF-1, FGF-2, and both reference biomarkers differed by HIV and MAD status. For example, FGF-1 levels were lower in subjects who had either HIV or MAD than in HIV– and MAD– controls (P=0.003. Multivariable regression identified that global NC impairment was associated with an interaction between FGF-1 and FGF-2 (model R2=0.09, P=0.01: higher FGF-2 levels were only associated with neurocognitive impairment among subjects who had lower FGF-1 levels. Including other covariates in the model (including antidepressant use strengthened the model (model R2=0.18, P=0.004 but did not weaken the association with FGF-1 and FGF-2. Lower FGF-1 levels were associated with impairment
Institute of Scientific and Technical Information of China (English)
Ying-hui CHEN; Cui-cui WANG; Xia XIAO; Li WEI; Guoxiong XU
2013-01-01
Aim:To investigate whether multidrug resistance-associated protein 1 (MRP1) was responsible for drug resistence in refractory epilepsy in amygdale kindling rats.Methods:Rat amygdale kindling was used as a model of refractory epilepsy.The expression of MRP1 mRNA and protein in the brains was examined using RT-PCR and Western blot.MRP1-positive cells in the cortex and hippocampus were studied with immunohistochemical staining.The rats were intraperitoneally injected with phenytoin (50 mg/kg) or carbamazepine (20 mg/kg),and their concentrations in the cortical extracellular fluid were measured using microdialysis and HPLC.Probenecid,a MRP1 inhibitor (40 mmol/L,50 μL) was administered through an inflow tube into the cortex 30 min before injection of the antiepileptic drugs.Results:The expression of MRP1 mRNA and protein was significantly up-regulated in the cortex and hippocampus in amygdale kindling rats compared with the control group.Furthermore,the number of MRP1-positive cells in the cortex and hippocampus was also significantly increased in amygdale kindling rats.Microdialysis studies showed that the concentrations of phenytoin and carbamazepine in the cortical extracellular fluid were significantly decreased in amygdale kindling rats.Pre-administration of probenecid could restore the concentrations back to their control levels.Conclusion:Up-regulation of MRP1 is responsible for the resistance of brain cells to antiepileptic drugs in the amygdale kindling rats.
Mallants, Dirk; Simunek, Jirka; Gerke, Kirill
2015-04-01
Coal Seam Gas production generates large volumes of "produced" water that may contain compounds originating from the use of hydraulic fracturing fluids. Such produced water also contains elevated concentrations of naturally occurring inorganic and organic compounds, and usually has a high salinity. Leaching of produced water from storage ponds may occur as a result of flooding or containment failure. Some produced water is used for irrigation of specific crops tolerant to elevated salt levels. These chemicals may potentially contaminate soil, shallow groundwater, and groundwater, as well as receiving surface waters. This paper presents an application of scenario modelling using the reactive transport model for variably-saturated media HP1 (coupled HYDRUS-1D and PHREEQC). We evaluate the fate of hydraulic fracturing chemicals and naturally occurring chemicals in soil as a result of unintentional release from storage ponds or when produced water from Coal Seam Gas operations is used in irrigation practices. We present a review of exposure pathways and relevant hydro-bio-geo-chemical processes, a collation of physico-chemical properties of organic/inorganic contaminants as input to a set of generic simulations of transport and attenuation in variably saturated soil profiles. We demonstrate the ability to model the coupled processes of flow and transport in soil of contaminants associated with hydraulic fracturing fluids and naturally occurring contaminants.
Sandberg, Johan V; Jakobsson, Joel; Pålsson, Erik; Landén, Mikael; Mathé, Aleksander A
2014-12-01
The attempted and accomplished suicide rates in patients with bipolar disorder are 40-50% and 15-20%, respectively. No biological markers that help predict suicide been identified. Human and experimental animal data indicate that dysregulation of the neuropeptide Y (NPY) system plays a role in depression, anxiety, and posttraumatic stress disorder (PTSD). The aim of this study was to explore if low cerebrospinal fluid (CSF) NPY is associated with (1) past suicide attempts, (2) future suicide attempts, and (3) trait anxiety. Lumbar puncture was performed on 120 clinically stable patients with bipolar disorder enrolled in the St Göran Bipolar Project, where the number of previous suicide attempts was documented. NPY-like immunoreactivity (NPY-LI) was determined in cerebrospinal fluid (CSF). Patients were reexamined one year after the lumbar puncture and suicide attempts were recorded. NPY-LI was significantly lower in patients with a history of suicide attempt than in patients who had not attempted suicide prior to lumbar puncture. Importantly, NPY-LI was markedly lower in patients who made a suicide attempt during the follow-up period compared to patients who did not. Patients who attempted suicide during the follow-up also had markedly lower NPY-LI than those with previous suicide attempts who did not reattempt. Our results suggest that low CSF NPY-LI predicts future suicide attempts. The data are in line with the hypothesis that NPY signaling is altered in affective disorders and states of emotional dysregulation.
Institute of Scientific and Technical Information of China (English)
WANG HaiJun; GU Fang; HONG XiaoZhong; BA XinWu
2007-01-01
The equation of the state of the hydrogen bonding fluid system of AaDd type is studied by the principle of statistical mechanics. The influences of hydrogen bonds on the equation of state of the system are obtained based on the change in volume due to hydrogen bonds. Moreover, the number density fluctuations of both molecules and hydrogen bonds as well as their spatial correlation property are investigated. Furthermore, an equation describing relation between the number density correlation function of "molecules-hydrogen bonds" and that of molecules and hydrogen bonds is derived. As application,taking the van der Waals hydrogen bonding fluid as an example, we considered the effect of hydrogen bonds on its relevant statistical properties.
Ebato, Yuki; Miyata, Tatsuhiko
2016-05-01
Ornstein-Zernike (OZ) integral equation theory is known to overestimate the excess internal energy, Uex, pressure through the virial route, Pv, and excess chemical potential, μex, for one-component Lennard-Jones (LJ) fluids under hypernetted chain (HNC) and Kovalenko-Hirata (KH) approximatons. As one of the bridge correction methods to improve the precision of these thermodynamic quantities, it was shown in our previous paper that the method to apparently adjust σ parameter in the LJ potential is effective [T. Miyata and Y. Ebato, J. Molec. Liquids. 217, 75 (2016)]. In our previous paper, we evaluated the actual variation in the σ parameter by using a fitting procedure to molecular dynamics (MD) results. In this article, we propose an alternative method to determine the actual variation in the σ parameter. The proposed method utilizes a condition that the virial and compressibility pressures coincide with each other. This method can correct OZ theory without a fitting procedure to MD results, and possesses characteristics of keeping a form of HNC and/or KH closure. We calculate the radial distribution function, pressure, excess internal energy, and excess chemical potential for one-component LJ fluids to check the performance of our proposed bridge function. We discuss the precision of these thermodynamic quantities by comparing with MD results. In addition, we also calculate a corrected gas-liquid coexistence curve based on a corrected KH-type closure and compare it with MD results.
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Yuki Ebato
2016-05-01
Full Text Available Ornstein-Zernike (OZ integral equation theory is known to overestimate the excess internal energy, Uex, pressure through the virial route, Pv, and excess chemical potential, μex, for one-component Lennard-Jones (LJ fluids under hypernetted chain (HNC and Kovalenko-Hirata (KH approximatons. As one of the bridge correction methods to improve the precision of these thermodynamic quantities, it was shown in our previous paper that the method to apparently adjust σ parameter in the LJ potential is effective [T. Miyata and Y. Ebato, J. Molec. Liquids. 217, 75 (2016]. In our previous paper, we evaluated the actual variation in the σ parameter by using a fitting procedure to molecular dynamics (MD results. In this article, we propose an alternative method to determine the actual variation in the σ parameter. The proposed method utilizes a condition that the virial and compressibility pressures coincide with each other. This method can correct OZ theory without a fitting procedure to MD results, and possesses characteristics of keeping a form of HNC and/or KH closure. We calculate the radial distribution function, pressure, excess internal energy, and excess chemical potential for one-component LJ fluids to check the performance of our proposed bridge function. We discuss the precision of these thermodynamic quantities by comparing with MD results. In addition, we also calculate a corrected gas-liquid coexistence curve based on a corrected KH-type closure and compare it with MD results.
Edison, John R.; Monson, Peter A.
2013-06-01
This article addresses the accuracy of a dynamic mean field theory (DMFT) for fluids in porous materials [P. A. Monson, J. Chem. Phys. 128, 084701 (2008)], 10.1063/1.2837287. The theory is used to study the relaxation processes of fluids in pores driven by step changes made to a bulk reservoir in contact with the pore. We compare the results of the DMFT to those obtained by averaging over large numbers of dynamic Monte Carlo (DMC) simulation trajectories. The problem chosen for comparison is capillary condensation in slit pores, driven by step changes in the chemical potential in the bulk reservoir and involving a nucleation process via the formation of a liquid bridge. The principal difference between the DMFT results and DMC is the replacement of a distribution of nucleation times and location along the pore for the formation of liquid bridges by a single time and location. DMFT is seen to yield an otherwise qualitatively accurate description of the dynamic behavior.
Sørig, Simon A.; Clausen, Ole R.; Andresen, Katrine J.
2016-04-01
The western part of the Norwegian-Danish Basin is part of the Northern Permian Basin and encompasses a variety of Zechstein salt structures (pillows, rollers, diapirs and salt walls). The area has been studied for decades with respect to HC prospectively associated to salt structures as well a focus area for studies on conceptual evolution of salt structures and faults associated with the salt structures. Previous local studies on fluid migration and Direct Hydrocarbon Indicators (DHI's) in the area show a close relation between halo kinetics and local fluid migration. In the present study we have used3D seismic data (approximately 3500 km2) to identify and describe A: large diapirs which have been active until the youngest Cenozoic, B: medium sized diapirs being active until the early Cenozoic, C: salt relicts creating small non active pillows, and D: small satellite structures related to type A. The salt structures are evenly distributed across the studied area, and we conclude that the structures were initiated during the late Triassic due to depositional controlled differential loading combined with differential subsidence. DHI's are identified at various stratigraphic and structural settings associated to the salt structures and each structure type has different types of DHI's associated. The DHIs observed at the type A and B diapirs are located above or at the stem of the diapirs and are here interpreted as classic structural hydrocarbon traps associated with rising salt deforming the strata. However, the DHI's associated to type C salt pillows have a relatively small lateral extent, stratigraphically restricted to the Mesozoic succession; they are located above the apex of the pillow and have in general a seismically disturbed zone located beneath the DHI. The seismically disturbed zone resembles gas chimneys, but may also be related to minor deformation of the Mesozoic strata overlying the type C pillows. A biogenic origin of the gas in at least some of the
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Ying Liu
Full Text Available Recently, a large meta-analysis of five genome wide association studies (GWAS identified a novel locus (rs2718058 adjacent to NME8 that played a preventive role in Alzheimer's disease (AD. However, this link between the single nucleotide polymorphism (SNP rs2718058 and the pathology of AD have not been mentioned yet. Therefore, this study assessed the strength of association between the NME8 rs2718058 genotypes and AD-related measures including the cerebrospinal fluid (CSF amyloid beta, tau, P-tau concentrations, neuroimaging biomarkers and cognitive performance, in a large cohort from Alzheimer's Disease Neuroimaging Initiative (ADNI database. We used information of a total of 719 individuals, including 211 normal cognition (NC, 346 mild cognitive impairment (MCI and 162 AD. Although we didn't observe a positive relationship between rs2718058 and AD, it was significantly associated with several AD related endophenotypes. Among the normal cognitively normal participants, the minor allele G carriers showed significantly associated with higher CDRSB score than A allele carriers (P = 0.021. Occipital gyrus atrophy were significantly associated with NME8 genotype status (P = 0.002, with A allele carriers has more atrophy than the minor allele G carriers in AD patients; lateral ventricle (both right and left cerebral metabolic rate for glucose (CMRgl were significantly associated with NME8 genotype (P < 0.05, with GA genotype had higher metabolism than GG and AA genotypes in MCI group; the atrophic right hippocampus in 18 months is significantly different between the three group, with GG and AA genotypes had more hippocampus atrophy than GA genotypes in the whole group. Together, our results are consistent with the direction of previous research, suggesting that NME8 rs2718058 appears to play a role in lowering the brain neurodegeneration.
Kushnir, Mark M; Naessén, Tord; Wanggren, Kjell; Hreinsson, Julius; Rockwood, Alan L; Meikle, A Wayne; Bergquist, Jonas
2016-09-01
Steroid concentrations in stimulated follicular fluid (sFF) samples have been linked to the quality of oocytes used in IVF treatments. Most of the published studies focused on evaluating the association of the IVF outcomes with only a few of the steroids, measured by immunoassays (IA). We performed a treatment outcome, prospective cohort study using stimulated FF sampled from 14 infertile women undergoing IVF treatment; single oocyte was used per IVF cycle. Fourteen endogenous steroids were analyzed in 22 ovarian follicle aspirations, which corresponded to the embryos used in the IVF. Ten oocytes were associated with live birth (LB) and 12 with no pregnancy (NP). Steroids were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. Differences in distribution of concentrations in association with the pregnancy outcome (LB or NP), and receiver operating characteristic (ROC) curves analysis were performed for the entire cohort and for within-women data. The predominant androgen and estrogen in stimulated sFF were androstenedione (A4) and estradiol (E2), respectively. Lower concentrations of pregnenolone (Pr), lower ratios of A4/ dehydroepiandrosterone (DHEA), testosterone (Te)/DHEA, and greater ratios of E2/Te, and estrone/A4 were observed in sFF samples associated with LB. Among the oocytes associated with NP, in four out of 12 samples total concentration of androgens was above the distribution of the concentrations in the oocytes corresponding to the LB group. Observations of the study indicated increased consumption of precursors and increased biosynthesis of estrogens in the follicles associated with LB. Our data suggest that potentially steroid profiles in sFF obtained during oocyte retrieval may serve as biomarkers for selection of the best embryo to transfer after IVF.
Behavior of boundary string field theory associated with integrable massless flow.
Fujii, A; Itoyama, H
2001-06-04
We put forward an idea that the boundary entropy associated with integrable massless flow of thermodynamic Bethe ansatz (TBA) is identified with tachyon action of boundary string field theory. We show that the temperature parametrizing a massless flow in the TBA formalism can be identified with tachyon energy for the classical action at least near the ultraviolet fixed point, i.e., the open string vacuum.
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Uddin, M. J., E-mail: josim.phys2007@gmail.com; Alam, M. S.; Mamun, A. A. [Department of Physics, Jahangirnagar University, Savar, Dhaka 1342 (Bangladesh)
2015-06-15
A theoretical investigation is made on the positron-acoustic (PA) shock waves (SHWs) in an unmagnetized electron-positron-ion plasma containing immobile positive ions, cold mobile positrons, and hot positrons and electrons following the kappa (κ) distribution. The cold positron kinematic viscosity is taken into account, and the reductive perturbation method is used to derive the Burgers equation. It is found that the viscous force acting on cold mobile positron fluid is a source of dissipation and is responsible for the formation of the PA SHWs. It is also observed that the fundamental properties of the PA SHWs are significantly modified by the effects of different parameters associated with superthermal (κ distributed) hot positrons and electrons.
Ueland, Maiken; Nizio, Katie D; Forbes, Shari L; Stuart, Barbara H
2015-10-01
Textiles are a commonly encountered source of evidence in forensic cases. In the past, most research has been focused on how textiles affect the decomposition process while little attention has been paid to how the decomposition products interact with the textiles. While some studies have shown that the presence of remains will have an effect on the degradation of clothing associated with a decaying body, very little work has been carried out on the specific mechanisms that prevent or delay textile degradation when in contact with decomposing remains. In order to investigate the effect of decomposition fluid on textile degradation, three clothed domestic pig (Sus scrofa domesticus) carcasses were placed on a soil surface, textile specimens were collected over a period of a year and were then analysed using ATR-FTIR spectroscopy and GC-MS. Multivariate statistical analysis was used to analyse the data. Cotton specimens not associated with remains degraded markedly, whereas the samples exposed to decomposition fluids remained relatively intact over the same time frame. An investigation of the decomposition by-products found that the protein-related bands remained stable and unchanged throughout the experiment. Lipid components, on the other hand, demonstrated a significant change; this was confirmed with the use of both ATR-FTIR spectroscopy and GC-MS. Through an advanced statistical approach, information about the decomposition by-products and their characteristics was obtained. There is potential that the lipid profile in a textile specimen could be a valuable tool used in the examination of clothing located at a crime scene.
Induced Seismicity Associated with Waste Fluid Injection into Deep Wells in Youngstown, Ohio
Kim, W.
2012-12-01
Since March 2011, residents in Youngstown, Ohio area experienced small earthquakes (M ~2.5). By 25 November 2011, about a dozen small but felt earthquakes have occurred around Youngstown. On 1 Dec. 2011 four portable seismographs were deployed around the epicentral area to monitor seismicity at close distances and determine hypocenters of the small earthquakes accurately, because these shocks were occurring close to a deep waste fluid injection well that began injection operation on 28 Dec. 2010. On 24 December 2011, a magnitude 2.7 shock occurred in the epicentral area which was accurately located by using the portable station data. The 24 Dec. shock is located about 800 m from the injection well and at a depth of 3.5 km, suggesting that those earthquakes in Youngstown could have been induced by the deep well injection operation. Hence, the injection was stopped on 30 Dec. 2011. However, the largest earthquake in the sequence (M4.0) occurred on 31 December 2011 within about 24 hours from halting injection operation. A total of 196 shocks are recorded during Dec. 2011 - April 2012. These shocks occurred as three distinct clusters of events, and a swarm of 82 small events. Three clusters of shocks have occurred in the narrow depth range (3.5-3.9 km) and the clusters appear to be on parallel faults of similar orientation offset by about 200-300 m apart. The swarm of small shocks (M -0.3 - 0.1) have occurred on 18 Feb. 2012 and lasted only few hours (12:36-15:46). These swarm events all lie in a very small region with depth range 3.8-4.2 km. The Precambrian basement rock in the region is at a depth 2.7 km, and hence all the shocks have occurred within in the Precambrian basement. Focal mechanism of the main shock is predominantly strike-slip faulting along steeply dipping nodal planes. The orientation of the WSW striking nodal plane (265 degree) is consistent with the lineation of the main cluster of shocks that include well-located main shock and other two largest
Investigation of the Phase Equilibria and Interfacial Properties for Non-polar Fluids
Institute of Scientific and Technical Information of China (English)
付东; 赵毅
2005-01-01
A self-consistent density-functional theory (DFT) was applied to investigate the phase behavior and interfacial properties of non-polar fluids. For the bulk phases, the theory was reduced to the statistical associating fluid theory(SAFF) that provides accurate descriptions of vapor-liquid phase diagrams below the critical region. The phase diagrams in the critical region were corrected by the renormalization group theory (RGT). The density profile in the surface was obtained by minimizing the grand potential. With the same set of molecular parameters, both the phase equilibria and the interfacial properties of non-polar fluids were investigated satisfactorily.
Dahms, Rainer N
2015-05-01
The fidelity of Gradient Theory simulations depends on the accuracy of saturation properties and influence parameters, and require equations of state (EoS) which exhibit a fundamentally consistent behavior in the two-phase regime. Widely applied multi-parameter EoS, however, are generally invalid inside this region. Hence, they may not be fully suitable for application in concert with Gradient Theory despite their ability to accurately predict saturation properties. The commonly assumed temperature-dependence of pure component influence parameters usually restricts their validity to subcritical temperature regimes. This may distort predictions for general multi-component interfaces where temperatures often exceed the critical temperature of vapor phase components. Then, the calculation of influence parameters is not well defined. In this paper, one of the first studies is presented in which Gradient Theory is combined with a next-generation Helmholtz energy EoS which facilitates fundamentally consistent calculations over the entire two-phase regime. Illustrated on pentafluoroethane as an example, reference simulations using this method are performed. They demonstrate the significance of such high-accuracy and fundamentally consistent calculations for the computation of interfacial properties. These reference simulations are compared to corresponding results from cubic PR EoS, widely-applied in combination with Gradient Theory, and mBWR EoS. The analysis reveals that neither of those two methods succeeds to consistently capture the qualitative distribution of obtained key thermodynamic properties in Gradient Theory. Furthermore, a generalized expression of the pure component influence parameter is presented. This development is informed by its fundamental definition based on the direct correlation function of the homogeneous fluid and by presented high-fidelity simulations of interfacial density profiles. The new model preserves the accuracy of previous temperature
Directory of Open Access Journals (Sweden)
Caimmi R.
2008-01-01
Full Text Available A theory of collisionless fluids is developed in a unified picture, where nonrotating (Ωf1 = Ωf2 = Ωf3 = 0 figures with some given random velocity component distributions, and rotating (Ωf1 = Ωf2 = Ωf3 figures with a different random velocity component distributions, make adjoint configurations to the same system. R fluids are defined as ideal, self-gravitating fluids satisfying the virial theorem assumptions, in presence of systematic rotation around each of the principal axes of inertia. To this aim, mean and rms angular velocities and mean and rms tangential velocity components are expressed, by weighting on the moment of inertia and the mass, respectively. The figure rotation is defined as the mean angular velocity, weighted on the moment of inertia, with respect to a selected axis. The generalized tensor virial equations (Caimmi and Marmo 2005 are formulated for R fluids and further attention is devoted to axisymmetric configurations where, for selected coordinate axes, a variation in figure rotation has to be counterbalanced by a variation in anisotropy excess and vice versa. A microscopical analysis of systematic and random motions is performed under a few general hypotheses, by reversing the sign of tangential or axial velocity components of an assigned fraction of particles, leaving the distribution function and other parameters unchanged (Meza 2002. The application of the reversion process to tangential velocity components is found to imply the conversion of random motion rotation kinetic energy into systematic motion rotation kinetic energy. The application of the reversion process to axial velocity components is found to imply the conversion of random motion translation kinetic energy into systematic motion translation kinetic energy, and the loss related to a change of reference frame is expressed in terms of systematic motion (imaginary rotation kinetic energy. A number of special situations are investigated in greater
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Sonia Molina-Pinelo
2012-01-01
Full Text Available The identification of new less invasive biomarkers is necessary to improve the detection and prognostic outcome of respiratory pathological processes. The measurement of miRNA expression through less invasive techniques such as plasma and serum have been suggested to analysis of several lung malignancies including lung cancer. These studies are assuming a common deregulated miRNA expression both in blood and lung tissue. The present study aimed to obtain miRNA representative signatures both in plasma and bronchoalveolar cell fraction that could serve as biomarker in respiratory diseases. Ten patients were evaluated to assess the expression levels of 381 miRNAs. We found that around 50% miRNAs were no detected in both plasma and bronchoalveolar cell fraction and only 20% of miRNAs showed similar expression in both samples. These results show a lack of association of miRNA signatures between plasma and bronchoalveolar cytology in the same patient. The profiles are not comparable; however, there is a similarity in the relative expression in a very small subset of miRNAs (miR-17, miR-19b, miR-195 and miR-20b between both biological samples in all patients. This finding supports that the miRNAs profiles obtained from different biological samples have to be carefully validated to link with respiratory diseases.
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Diego M Morales
Full Text Available Neurological outcomes of preterm infants with post-hemorrhagic hydrocephalus (PHH remain among the worst in infancy, yet there remain few instruments to inform the treatment of PHH. We previously observed PHH-associated elevations in cerebrospinal fluid (CSF amyloid precursor protein (APP, neural cell adhesion molecule-L1 (L1CAM, neural cell adhesion molecule-1 (NCAM-1, and other protein mediators of neurodevelopment.The objective of this study was to examine the association of CSF APP, L1CAM, and NCAM-1 with ventricular size as an early step toward developing CSF markers of PHH.CSF levels of APP, L1CAM, NCAM-1, and total protein (TP were measured in 12 preterm infants undergoing PHH treatment. Ventricular size was determined using cranial ultrasounds. The relationships between CSF APP, L1CAM, and NCAM-1, occipitofrontal circumference (OFC, volume of CSF removed, and ventricular size were examined using correlation and regression analyses.CSF levels of APP, L1CAM, and NCAM-1 but not TP paralleled treatment-related changes in ventricular size. CSF APP demonstrated the strongest association with ventricular size, estimated by frontal-occipital horn ratio (FOR (Pearson R = 0.76, p = 0.004, followed by NCAM-1 (R = 0.66, p = 0.02 and L1CAM (R = 0.57,p = 0.055. TP was not correlated with FOR (R = 0.02, p = 0.95.Herein, we report the novel observation that CSF APP shows a robust association with ventricular size in preterm infants treated for PHH. The results from this study suggest that CSF APP and related proteins at once hold promise as biomarkers of PHH and provide insight into the neurological consequences of PHH in the preterm infant.
The associated factors to endometrial cavity fluid and the relevant impact on the IVF-ET outcome
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Li Ya-Qiong
2010-05-01
Full Text Available Abstract Background Endometrial cavity fluid (ECF is a fluid accumulation within the endometrial cavity. The significance of ECF remains unclear during the program of in vitro fertilization-embryo transfer (IVF-ET. The aim of the present study was to investigate the associated factors to ECF, visualized through ultrasound at the day of oocyte retrieval, and the relevant impact on the outcome of IVF-ET. Methods From the clinical data of 1557 infertility patients for IVF-ET program, 46 ECF patients were retrospectively selected as the ECF group; and another 134 patients with a bilateral salpingectomy and without ECF, selected as the control group. The demographics and the outcome of IVF-ET were compared between the two groups. Results The incidence of ECF was 2.95% (46/1557. Over half (28/46, 60.87% of ECF patients had tubal infertility. Only 12 Of 46 ECF patients (26.09% had visible hydrosalpinx on ultrasonography before ovarian stimulation. The cycle cancellation rate (4/46, 8.69% of ECF group was not significantly higher than that of the control group (6/134, 4.48%; P > 0.05. Reasons for cycle cancellation in both groups were all the high risk of ovarian hyperstimulation syndrome (OHSS. No significant difference was found in clinical pregnancy rate between the patients with their ECF 0.05. No clinical pregnancy was found among those patients with their ECF equal or higher 3.5 mm in APD. Conclusions It was tubal infertility, not hydrosalpinx, which was related to the development of ECF. Excessive ECF (equal or higher 3.5 mm in APD at the day of oocyte retrieval would have a negative impact on the outcome of IVF-ET.
Bijttebier, Patricia; Beck, Ilse; Claes, Laurence; Vandereycken, Walter
2009-07-01
Gray's Reinforcement Sensitivity Theory (RST) presupposes individual differences in the sensitivity of basic brain systems that respond to punishing and reinforcing stimuli. These differences are thought to underlie the personality dimensions of anxiety and impulsivity, and to have relevance for psychopathology. The present article aims at reviewing RST-based research on personality-psychopathology associations. First, RST and its revisions are described and the link between RST systems and personality dimensions is discussed. Second, studies investigating associations between RST systems and specific types of psychopathology are summarized. Although the available research yields a rather consistent picture with respect to constellations of BIS/BAS sensitivity that are associated with specific types of psychopathology, it also provides a clear indication that much work remains to be done. The discussion section highlights several topics that deserve future research attention.
Engler, H; Brendt, P; Wischermann, J; Wegner, A; Röhling, R; Schoemberg, T; Meyer, U; Gold, R; Peters, J; Benson, S; Schedlowski, M
2017-01-31
Systemic inflammation is accompanied by profound behavioral and mood changes that resemble symptoms of depression. Findings in animals suggest that pro-inflammatory cytokines released by activated immune cells in the periphery evoke these behavioral symptoms by driving inflammatory changes in the brain. However, experimental data in humans are lacking. Here we demonstrate in healthy male volunteers (10 endotoxin treated, 8 placebo treated) that intravenous administration of low-dose endotoxin (0.8 ng/kg body weight), a prototypical pathogen-associated molecular pattern that activates the innate immune system, not only induces a significant increase in peripheral blood cytokine concentrations (that is, tumor necrosis factor-α, interleukin (IL)-6, IL-10) but also results, with some latency, in a robust and selective increase of IL-6 in the cerebrospinal fluid (CSF). Moreover, we found a strong association between the endotoxin-induced increase of IL-6 in the CSF and the severity of mood impairment, with larger increases in CSF IL-6 concentration followed by a greater deterioration in mood. Taken together, these findings suggest that the appearance of depressive symptoms in inflammatory conditions might be primarily linked to an increase in central IL-6 concentration, identifying IL-6 as a potential therapeutic target in mood disorders.Molecular Psychiatry advance online publication, 31 January 2017; doi:10.1038/mp.2016.264.
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Kim, Kyung Won; Shinagare, Atul B.; Krajewski, Katherine M.; Tirumani, Sree Harsha; Jagannathan, Jyothi P.; Ramaiya, Nikihil H. [Dept. of Imaging, Dana-Farber Cancer Institute, Brigham and Women' s Hospital, Harvard Medical School, Boston (United States); Pyo, Jun Hee [The Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, Boston (United States)
2015-04-15
We aimed to describe radiologic signs and time-course of imatinib-associated fluid retention (FR) in patients with gastrointestinal stromal tumor (GIST), and its implications for management. In this Institutional Review Board-approved, retrospective study of 403 patients with GIST treated with imatinib, 15 patients with imaging findings of FR were identified by screening radiology reports, followed by manual confirmation. Subcutaneous edema, ascites, pleural effusion, and pericardial effusion were graded on a four-point scale on CT scans; total score was the sum of these four scores. The most common radiologic sign of FR was subcutaneous edema (15/15, 100%), followed by ascites (12/15, 80%), pleural effusion (11/15, 73%), and pericardial effusion (6/15, 40%) at the time of maximum FR. Two distinct types of FR were observed: 1) acute/progressive FR, characterized by acute aggravation of FR and rapid improvement after management, 2) intermittent/steady FR, characterized by occasional or persistent mild FR. Acute/progressive FR always occurred early after drug initiation/dose escalation (median 1.9 month, range 0.3-4.0 months), while intermittent/steady FR occurred at any time. Compared to intermittent/steady FR, acute/progressive FR was severe (median score, 5 vs. 2.5, p = 0.002), and often required drug-cessation/dose-reduction. Two distinct types (acute/progressive and intermittent/steady FR) of imatinib-associated FR are observed and each type requires different management.
Dharma-wardana, M W C
2016-01-01
Using data from recent laser-shock experiments and related density-functional molecular-dynamics simulations on carbon, we demonstrate that the ionic structures predicted within the neutral-pseudo-atom approach for a complex liquid in the warm-dense matter regime are in good agreement with available data, even where transient covalent bonding dominates ionic correlations. Evidence for an unusual phase transition of a liquid $\\to$ vapor with an abrupt decrease in ionization occurring simultaneously is presented. Here a covalently-bonded metallic-liquid, i.e., carbon of density 1.0 g/cm$^3$, transits to a disordered mono-atomic fluid at 7 eV. Other transitions where the mean ionization $Z$ drops abruptly are also uncovered
Institute of Scientific and Technical Information of China (English)
CHEN Lu-wang; QIN Yuan; GUI He-rong; ZHANG Shi-lei
2012-01-01
To study the behavior of overlying strata and the likelihood of water inrush and quicksand with different mining sequences under an unconsolidated alluvium aquifer,a numerical model based on the fluid-solid coupling theory was constructed by FLAC3D.Simulation results revealed that the mining sequences had a significant influence on the seepage,displacement and failure characteristics of the overlying strata.In this kind of geological and hydrogeological conditions,the workface close to the outcrop of coal seam easily suffers from water inrush and quicksand during mining.In the simulation resuits,the plastic zone,vertical displacement and pore water pressure in the overlying strata of the workface decrease more or less using the upward mining sequence than using the downward mining sequence.Therefore,the application of the upward mining sequence in the process of mining is preferential to prevent water inrush and quicksand.
Directory of Open Access Journals (Sweden)
Caimmi, R.
2008-06-01
Full Text Available A theory of collisionless fluids is developed in a unified picture, where nonrotating $(widetilde{Omega_1}=widetilde{Omega_2}= widetilde{Omega_3}=0$ figures with some given random velocity component distributions, and rotating $(widetilde{Omega_1} ewidetilde{Omega_2} e widetilde{Omega_3} $ figures with a different random velocity component distributions, make adjoint configurations to the same system. R fluids are defined as ideal, self-gravitating fluids satisfying the virial theorem assumptions, in presence of systematic rotation around each of the principal axes of inertia. To this aim, mean and rms angular velocities and mean and rms tangential velocity components are expressed, by weighting on the moment of inertia and the mass, respectively. The figure rotation is defined as the mean angular velocity, weighted on the moment of inertia, with respectto a selected axis. The generalized tensor virial equations (Caimmi and Marmo 2005 are formulated for R fluidsand further attention is devoted to axisymmetric configurations where, for selected coordinateaxes, a variation in figure rotation has to be counterbalanced by a variation in anisotropy excess and viceversa. A microscopical analysis of systematic and random motions is performed under a fewgeneral hypotheses, by reversing the sign of tangential or axial velocity components of anassigned fraction of particles, leaving the distribution function and other parametersunchanged (Meza 2002. The application of the reversion process to tangential velocitycomponents is found to imply the conversion of random motion rotation kinetic energy intosystematic motion rotation kinetic energy. The application ofthe reversion process to axial velocity components is found to imply the conversionof random motion translation kinetic energy into systematic motion translation kinetic energy, and theloss related to a change of reference frame is expressed in terms of systematic motion (imaginary rotation kinetic
Directory of Open Access Journals (Sweden)
Joseph N Jarvis
2015-04-01
Full Text Available Understanding the host immune response during cryptococcal meningitis (CM is of critical importance for the development of immunomodulatory therapies. We profiled the cerebrospinal fluid (CSF immune-response in ninety patients with HIV-associated CM, and examined associations between immune phenotype and clinical outcome. CSF cytokine, chemokine, and macrophage activation marker concentrations were assayed at disease presentation, and associations between these parameters and microbiological and clinical outcomes were examined using principal component analysis (PCA. PCA demonstrated a co-correlated CSF cytokine and chemokine response consisting primarily of Th1, Th2, and Th17-type cytokines. The presence of this CSF cytokine response was associated with evidence of increased macrophage activation, more rapid clearance of Cryptococci from CSF, and survival at 2 weeks. The key components of this protective immune-response were interleukin (IL-6 and interferon-γ, IL-4, IL-10 and IL-17 levels also made a modest positive contribution to the PC1 score. A second component of co-correlated chemokines was identified by PCA, consisting primarily of monocyte chemotactic protein-1 (MCP-1 and macrophage inflammatory protein-1α (MIP-1α. High CSF chemokine concentrations were associated with low peripheral CD4 cell counts and CSF lymphocyte counts and were predictive of immune reconstitution inflammatory syndrome (IRIS. In conclusion CSF cytokine and chemokine profiles predict risk of early mortality and IRIS in HIV-associated CM. We speculate that the presence of even minimal Cryptococcus-specific Th1-type CD4+ T-cell responses lead to increased recruitment of circulating lymphocytes and monocytes into the central nervous system (CNS, more effective activation of CNS macrophages and microglial cells, and faster organism clearance; while high CNS chemokine levels may predispose to over recruitment or inappropriate recruitment of immune cells to the CNS and
Shimura, Shinichiro; Cho, Yasunori; Aki, Akira; Ueda, Toshihiko
2013-12-01
We present a case of a 49-year old man who suffered from immediate paraplegia upon awakening from anaesthesia after surgery for acute aortic dissection Type A. A catheter was promptly inserted into the spinal canal for cerebrospinal fluid drainage, and the cerebrospinal fluid pressure was maintained paraplegia and was able to walk by himself after rehabilitation. In some cases, cerebrospinal fluid drainage can be effective for the treatment of immediate postoperative spinal cord damage.
Morales, Fernando A
2016-01-01
For a fissured medium with uncertainty in the knowledge of fractures' geometry, a conservative tangential flow field is constructed, which is consistent with the physics of stationary fluid flow in porous media and an interpolated geometry of the cracks. The flow field permits computing preferential fluid flow directions of the medium, rates of mechanical energy dissipations and a stochastic matrix modeling stream lines and fluid mass transportation, for the analysis of solute/contaminant mass advection-diffusion as well as drainage times.
Links, J M; Schwartz, B S; Simon, D; Bandeen-Roche, K; Stewart, W F
2001-04-01
We present a theoretical approach to analysis of toxicokinetics and toxicodynamics using linear systems theory. In our approach, we define two impulse response functions that characterize the kinetic behavior of an environmental agent in the body and the dynamic time-course behavior of its effect on the body. This approach provides a formalism for understanding the relation among exposure, dose, and cumulative biologically effective dose and for understanding the implications of an effect time-course on cross-sectional and longitudinal data analyses. We use lead-associated cognitive decline as a specific example where the approach may be applied.
Tretyakov, Nikita; Vollmer, Doris; Butt, Hans-Jürgen; Dünweg, Burkhard; Daoulas, Kostas Ch
2016-01-01
Classical density functional theory is applied to investigate the validity of a phenomenological force-balance description of the stability of the Cassie state of liquids on substrates with nanoscale corrugation. A bulk free-energy functional of third order in local density is combined with a square-gradient term, describing the liquid-vapor interface. The bulk free energy is parameterized to reproduce the liquid density and the compressibility of water. The square-gradient term is adjusted to model the width of the water-vapor interface. The substrate is modeled by an external potential, based upon Lennard-Jones interactions. The three-dimensional calculation focuses on substrates patterned with nanostripes and square-shaped nanopillars. Using both the force-balance relation and density-functional theory, we locate the Cassie-to-Wenzel transition as a function of the corrugation parameters. We demonstrate that the force-balance relation gives a qualitatively reasonable description of the transition even on t...
Mazzanti, P.; Bozzano, F.
2009-11-01
Coastal and subaqueous landslides can be very dangerous phenomena since they are characterised by the additional risk of induced tsunamis, unlike their completely-subaerial counterparts. Numerical modelling of landslides propagation is a key step in forecasting the consequences of landslides. In this paper, a novel approach named Equivalent Fluid/Equivalent Medium (EFEM) has been developed. It adapts common numerical models and software that were originally designed for subaerial landslides in order to simulate the propagation of combined subaerial-subaqueous and completely-subaqueous landslides. Drag and buoyancy forces, the loss of energy at the landslide-water impact and peculiar mechanisms like hydroplaning can be suitably simulated by this approach; furthermore, the change in properties of the landslide's mass, which is encountered at the transition from the subaerial to the submerged environment, can be taken into account. The approach has been tested by modelling two documented coastal landslides (a debris flow and a rock slide at Lake Albano) using the DAN-W code. The results, which were achieved from the back-analyses, demonstrate the efficacy of the approach to simulate the propagation of different types of coastal landslides.
Bianchi type-V cosmological models with perfect fluid and heat flow in Saez–Ballester theory
Indian Academy of Sciences (India)
Shri Ram; M Zeyauddin; C P Singh
2009-02-01
In this paper we discuss the variation law for Hubble's parameter with average scale factor in a spatially homogeneous and anisotropic Bianchi type-V space-time model, which yields constant value of the deceleration parameter. We derive two laws of variation of the average scale factor with cosmic time, one is of power-law type and the other is of exponential form. Exact solutions of Einstein field equations with perfect fluid and heat conduction are obtained for Bianchi type-V space-time in these two types of cosmologies. In the cosmology with the power-law, the solutions correspond to a cosmological model which starts expanding from the singular state with positive deceleration parameter. In the case of exponential cosmology, we present an accelerating non-singular model of the Universe. We find that the constant value of deceleration parameter is reasonable for the present day Universe and gives an appropriate description of evolution of Universe. We have also discussed different types of physical and kinematical behaviour of the models in these two types of cosmologies.
Directory of Open Access Journals (Sweden)
P. Mazzanti
2009-11-01
Full Text Available Coastal and subaqueous landslides can be very dangerous phenomena since they are characterised by the additional risk of induced tsunamis, unlike their completely-subaerial counterparts. Numerical modelling of landslides propagation is a key step in forecasting the consequences of landslides. In this paper, a novel approach named Equivalent Fluid/Equivalent Medium (EFEM has been developed. It adapts common numerical models and software that were originally designed for subaerial landslides in order to simulate the propagation of combined subaerial-subaqueous and completely-subaqueous landslides. Drag and buoyancy forces, the loss of energy at the landslide-water impact and peculiar mechanisms like hydroplaning can be suitably simulated by this approach; furthermore, the change in properties of the landslide's mass, which is encountered at the transition from the subaerial to the submerged environment, can be taken into account. The approach has been tested by modelling two documented coastal landslides (a debris flow and a rock slide at Lake Albano using the DAN-W code. The results, which were achieved from the back-analyses, demonstrate the efficacy of the approach to simulate the propagation of different types of coastal landslides.
DEFF Research Database (Denmark)
Larsson, S; Englund, M; Struglics, A;
2012-01-01
OBJECTIVE: To investigate whether change in concentrations over time of aggrecanase generated ARGS-aggrecan in synovial fluid (SF ARGS) associates with progression of radiographic knee osteoarthritis (OA) and patient-reported outcome in subjects with previous meniscectomy. METHODS: We studied 141...
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
In order to resolve the multisensor multiplied maneuvering target tracking problem, this paper presents a distributed interacted multiple model multisensor joint probabilistic data association algorithm (DIMM-MSJPDA). First of all, the interacted multiple model joint probabilistic data association algorithm is applied to each sensor, and then the state estimation, estimation covariance, model probability, combined innovation, innovation covariance are delivered to the fusion center. Then, the tracks from each sensor are correlated and the D-S evidence theory is used to gain the model probability of an identical target. Finally, the ultimate state estimation of each target is calculated according to the new model probability, and the state estimation is transmitted to each sensor. Simulations are designed to test the tracking performance of DIMM-MSJPDA algorithm. The results show that the use of DIMM-MSJPDA algorithm enables the distributed multisensor system to track multiplied maneuvering targets and its tracking performance is much better than that of IMMJPDA algorithm.
Matsusue, Aya; Ishikawa, Takaki; Michiue, Tomomi; Waters, Brian; Hara, Kenji; Kashiwagi, Masayuki; Takayama, Mio; Ikematsu, Natsuki; Kubo, Shin-Ichi
2017-01-01
Methamphetamine (MA) is an illicit psychostimulant that stimulates the release of catecholamines from sympathetic nerve terminals and is widely abused worldwide. Since catechol-O-methyltransferase (COMT) metabolizes catecholamines and mediates adrenergic, noradrenergic, and dopaminergic signaling responses, we investigated the effects of the COMT polymorphisms rs4633 and rs4680 on cerebrospinal fluid (CSF) catecholamine concentrations in autopsies of subjects who died of drug intoxication. 28 MA abusers and 22 fatal psychotropic drug intoxication cases were evaluated. No correlations were identified between rs4633 or rs4680 polymorphisms and CSF concentrations of adrenaline (Adr), noradrenaline (Nad), or dopamine (DA) in fatal psychotropic cases. However, among MA abusers, DA concentrations in the CSF were significantly higher in those with the T allele (CT and TT) of rs4633 than in CC genotype carriers (p=0.004). Moreover, among MA abusers, DA concentrations were significantly higher in those with the A allele (GA and AA) of rs4680 than in GG genotype carriers (p=0.017). In subsequent haplotype analyses of MA abusers, a strong correlation was identified between two COMT haplotypes and CSF DA concentrations (p=0.002). However, the CSF concentrations of Adr and Nad were not associated with COMT genotypes or haplotypes. The present results indicate that rs4633 and rs4680 polymorphisms influence CSF DA concentrations and MA toxicity in MA abusers.
Kuroiwa, Masafumi; Kusano, Yoshikazu; Ogiwara, Toshihiro; Tanaka, Yuichiro; Takemae, Toshiki; Hongo, Kazuhiro
2014-01-01
Persisting embryonal infundibular recess (PEIR) is a rare anomaly of the third ventricular floor. Only eight cases have been published. In this report, a case of presumably Rathke's cleft cyst associated with cerebrospinal fluid leakage caused by PEIR is described. An 81-year-old woman underwent endoscopic transsphenoidal surgery for the intra- and supra-sellar cystic lesion. Intraoperatively a hole was confirmed over the sella turcica connecting the sellar cyst and the infundibular recess. Liquorrhea did not occur throughout the procedure. A computed tomography (CT) scan obtained immediately after surgery disclosed accumulation of air in the third and lateral ventricles, in addition to the intra- and supra-sellar region. Air accumulation resolved spontaneously after bed rest for 11 days and she was discharged without neurological deficits. However, she required the second transsphenoidal surgery to repair the sellar floor because of bacterial meningitis caused by liquorrhea on the postoperative day 23. A postoperative 3-tesla magnetic resonance image revealed a deep infundibular recess connecting the sella turcica and the third ventricle, which was considered to be PEIR. To the best our knowledge, this is the first reported case describing the intraoperative findings of PEIR.
Nold, Andreas; Sibley, David N.; Goddard, Benjamin D.; Kalliadasis, Serafim
2014-07-01
We examine the nanoscale behavior of an equilibrium three-phase contact line in the presence of long-ranged intermolecular forces by employing a statistical mechanics of fluids approach, namely, density functional theory (DFT) together with fundamental measure theory (FMT). This enables us to evaluate the predictive quality of effective Hamiltonian models in the vicinity of the contact line. In particular, we compare the results for mean field effective Hamiltonians with disjoining pressures defined through (i) the adsorption isotherm for a planar liquid film, and (ii) the normal force balance at the contact line. We find that the height profile obtained using (i) shows good agreement with the adsorption film thickness of the DFT-FMT equilibrium density profile in terms of maximal curvature and the behavior at large film heights. In contrast, we observe that while the height profile obtained by using (ii) satisfies basic sum rules, it shows little agreement with the adsorption film thickness of the DFT results. The results are verified for contact angles of 20°, 40°, and 60°.
Bird, R. Byron
1980-01-01
Problems in polymer fluid dynamics are described, including development of constitutive equations, rheometry, kinetic theory, flow visualization, heat transfer studies, flows with phase change, two-phase flow, polymer unit operations, and drag reduction. (JN)
Frederick, J. M.; Buffett, B. A.
2012-12-01
Permafrost-associated methane hydrate deposits along the shallow Arctic continental shelf are thought to be a relict of glacial periods, when a large volume of Earth's water was locked up in polar ice and sea levels were lower, exposing the continental shelves to sub-freezing temperatures. Because of the cold surface temperatures, hydrate deposits are potentially stable here at unusually shallow depths, creating an extensive near-surface carbon reservoir. However, re-submergence of the shelf due to rising sea levels since the last glacial maximum 18 kyr ago has brought a temperature change of roughly +18C to the surface sediments. The evolution of permafrost-associated methane hydrate deposits is potentially complex, and an understanding of the temperature field alone is not sufficient. Salt, which is concentrated in pore fluids when permafrost forms, substantially changes the growth and decay of both permafrost and methane hydrate. The permafrost, in particular, has a strong influence on the mobility of gas within the shelf sediments. In order to quantify these complex interactions we have developed a two-dimensional, finite-volume model for two-phase flow of pore fluid and methane gas within Arctic shelf sediments. We track the evolution of temperature, salinity, and pressure fields with prescribed boundary conditions, and account for latent heat of water ice formation during growth or decay of permafrost. The permeability structure of the sediments is coupled to changes in permafrost. The model can be run over several glacial cycles to simulate the natural environment in which Arctic hydrate deposits form, while also allowing us to explore the consequences of addition warming due to anthropogenic forcing. Preliminary results show that pore fluid and gas migration is strongly influenced by the permeability variations imposed by the overlying permafrost. When permafrost grows, high salinity pore fluids form as salt is excluded from ice. Increasing salinity
Shinagare, Atul B.; Krajewski, Katherine M.; Pyo, Junhee; Tirumani, Sree Harsha; Jagannathan, Jyothi P.; Ramaiya, Nikhil H.
2015-01-01
Objective We aimed to describe radiologic signs and time-course of imatinib-associated fluid retention (FR) in patients with gastrointestinal stromal tumor (GIST), and its implications for management. Materials and Methods In this Institutional Review Board-approved, retrospective study of 403 patients with GIST treated with imatinib, 15 patients with imaging findings of FR were identified by screening radiology reports, followed by manual confirmation. Subcutaneous edema, ascites, pleural effusion, and pericardial effusion were graded on a four-point scale on CT scans; total score was the sum of these four scores. Results The most common radiologic sign of FR was subcutaneous edema (15/15, 100%), followed by ascites (12/15, 80%), pleural effusion (11/15, 73%), and pericardial effusion (6/15, 40%) at the time of maximum FR. Two distinct types of FR were observed: 1) acute/progressive FR, characterized by acute aggravation of FR and rapid improvement after management, 2) intermittent/steady FR, characterized by occasional or persistent mild FR. Acute/progressive FR always occurred early after drug initiation/dose escalation (median 1.9 month, range 0.3-4.0 months), while intermittent/steady FR occurred at any time. Compared to intermittent/steady FR, acute/progressive FR was severe (median score, 5 vs. 2.5, p = 0.002), and often required drug-cessation/dose-reduction. Conclusion Two distinct types (acute/progressive and intermittent/steady FR) of imatinib-associated FR are observed and each type requires different management. PMID:25741192
Directory of Open Access Journals (Sweden)
Masaru Takeuchi
Full Text Available Macrophages are involved in low-grade inflammation in diabetes, and play pathogenic roles in proliferative diabetic retinopathy (PDR by producing proinflammatory cytokines. T cells as well as other cells are also activated by proinflammatory cytokines, and infiltration into the vitreous of patients with PDR has been shown. In this study, we measured helper T (Th cell-related cytokines in the vitreous of PDR patients to define the characteristics of Th-mediated immune responses associated with PDR. The study group consisted of 25 type 2 diabetic patients (25 eyes with PDR. The control group consisted of 27 patients with epiretinal membrane (ERM, 26 patients with idiopathic macular hole (MH, and 26 patients with uveitis associated with sarcoidosis. Vitreous fluid was obtained at the beginning of vitrectomy, and centrifuging for cellular removals was not performed. Serum was also collected from PDR patients. IL-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, IFN-γ, soluble sCD40L, and TNFα in the vitreous and serum samples were measured. Both percent detectable and levels of IL-4, IL-6, IL-17A, IL-21, IL-22, and TNFα in the vitreous were significantly higher than those in the serum in PDR patients. Vitreous levels of these cytokines and IL-31 were significantly higher in PDR than in ERM or MH patients. Vitreous levels of IL-4, IL-17A, IL-22, IL-31, and TNFα in PDR patients were also significantly higher than those of sarcoidosis patients. In PDR patients, vitreous IL-17A level correlated significantly with vitreous levels of IL-22 and IL-31, and especially with IL-4 and TNFα. Although it is unclear whether these cytokines play facilitative roles or inhibitory roles for the progression of PDR, the present study indicated that Th2- and Th17-related immune responses are involved in the pathogenesis of PDR.
Takeuchi, Masaru; Sato, Tomohito; Tanaka, Atsushi; Muraoka, Tadashi; Taguchi, Manzo; Sakurai, Yutaka; Karasawa, Yoko; Ito, Masataka
2015-01-01
Macrophages are involved in low-grade inflammation in diabetes, and play pathogenic roles in proliferative diabetic retinopathy (PDR) by producing proinflammatory cytokines. T cells as well as other cells are also activated by proinflammatory cytokines, and infiltration into the vitreous of patients with PDR has been shown. In this study, we measured helper T (Th) cell-related cytokines in the vitreous of PDR patients to define the characteristics of Th-mediated immune responses associated with PDR. The study group consisted of 25 type 2 diabetic patients (25 eyes) with PDR. The control group consisted of 27 patients with epiretinal membrane (ERM), 26 patients with idiopathic macular hole (MH), and 26 patients with uveitis associated with sarcoidosis. Vitreous fluid was obtained at the beginning of vitrectomy, and centrifuging for cellular removals was not performed. Serum was also collected from PDR patients. IL-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, IFN-γ, soluble sCD40L, and TNFα in the vitreous and serum samples were measured. Both percent detectable and levels of IL-4, IL-6, IL-17A, IL-21, IL-22, and TNFα in the vitreous were significantly higher than those in the serum in PDR patients. Vitreous levels of these cytokines and IL-31 were significantly higher in PDR than in ERM or MH patients. Vitreous levels of IL-4, IL-17A, IL-22, IL-31, and TNFα in PDR patients were also significantly higher than those of sarcoidosis patients. In PDR patients, vitreous IL-17A level correlated significantly with vitreous levels of IL-22 and IL-31, and especially with IL-4 and TNFα. Although it is unclear whether these cytokines play facilitative roles or inhibitory roles for the progression of PDR, the present study indicated that Th2- and Th17-related immune responses are involved in the pathogenesis of PDR.
Energy Technology Data Exchange (ETDEWEB)
Perfetti, E
2006-11-15
Modelling fluid-rock interactions as well as mixing and unmixing phenomena in geological processes requires robust equations of state (EOS) which must be applicable to systems containing water, gases over a broad range of temperatures and pressures. Cubic equations of state based on the Van der Waals theory (e. g. Soave-Redlich-Kwong or Peng-Robinson) allow simple modelling from the critical parameters of the studied fluid components. However, the accuracy of such equations becomes poor when water is a major component of the fluid since neither association trough hydrogen bonding nor dipolar interactions are accounted for. The Helmholtz energy of a fluid may be written as the sum of different energetic contributions by factorization of partition function. The model developed in this thesis for the pure H{sub 2}O and H{sub 2}S considers three contributions. The first contribution represents the reference Van der Waals fluid which is modelled by the SRK cubic EOS. The second contribution accounts for association through hydrogen bonding and is modelled by a term derived from Cubic Plus Association (CPA) theory. The third contribution corresponds to the dipolar interactions and is modelled by the Mean Spherical Approximation (MSA) theory. The resulting CPAMSA equation has six adjustable parameters, which three represent physical terms whose values are close to their experimental counterpart. This equation results in a better reproduction of the thermodynamic properties of pure water than obtained using the classical CPA equation along the vapour-liquid equilibrium. In addition, extrapolation to higher temperatures and pressure is satisfactory. Similarly, taking into account dipolar interactions together with the SRK cubic equation of state for calculating molar volume of H{sub 2}S as a function of pressure and temperature results in a significant improvement compared to the SRK equation alone. Simple mixing rules between dipolar molecules are proposed to model the H
Directory of Open Access Journals (Sweden)
Todd Yecies
2013-01-01
Full Text Available Spontaneous bacterial peritonitis (SBP is a potentially deadly complication of ascites. We describe a case of SBP caused by Listeria monocytogenes in a patient with alcoholic cirrhosis. This was associated with the unusual finding of ascitic fluid lymphocytosis, which previously had only been associated with tuberculoid or malignant ascites. Given increasing rates of cefotaxime-resistant SBP alongside the possibility of Listeriosis, the use of cefotaxime as first-line therapy in SBP should be reevaluated.
Gong, Kai; Marshall, Bennett D; Chapman, Walter G
2013-09-07
We study the lower critical solution temperature (LCST) behavior of associating polymer brushes (i.e., poly(N-isopropylacrylamide)) using classical density functional theory. Without using any empirical or temperature-dependent parameters, we find the phase transition of polymer brushes from extended to collapsed structure with increasing temperature, indicating the LCST behavior of polymer brushes. The LCST behavior of associating polymer brushes is attributed to the interplay of hydrogen bonding interactions and Lennard-Jones attractions in the system. The effect of grafting density and molecular weight on the phase behavior of associating polymer brushes has been also investigated. We find no LCST behavior at low grafting density or molecular weight. Moreover, increasing grafting density decreases the LCST and swelling ratio of polymer brushes. Similarly, increasing molecular weight decreases the LCST but increases the swelling ratio. At very high grafting density, a partial collapsed structure appears near the LCST. Qualitatively consistent with experiments, our results provide insight into the molecular mechanism of LCST behavior of associating polymer brushes.
Fluid mechanics in fluids at rest.
Brenner, Howard
2012-07-01
Using readily available experimental thermophoretic particle-velocity data it is shown, contrary to current teachings, that for the case of compressible flows independent dye- and particle-tracer velocity measurements of the local fluid velocity at a point in a flowing fluid do not generally result in the same fluid velocity measure. Rather, tracer-velocity equality holds only for incompressible flows. For compressible fluids, each type of tracer is shown to monitor a fundamentally different fluid velocity, with (i) a dye (or any other such molecular-tagging scheme) measuring the fluid's mass velocity v appearing in the continuity equation and (ii) a small, physicochemically and thermally inert, macroscopic (i.e., non-Brownian), solid particle measuring the fluid's volume velocity v(v). The term "compressibility" as used here includes not only pressure effects on density, but also temperature effects thereon. (For example, owing to a liquid's generally nonzero isobaric coefficient of thermal expansion, nonisothermal liquid flows are to be regarded as compressible despite the general perception of liquids as being incompressible.) Recognition of the fact that two independent fluid velocities, mass- and volume-based, are formally required to model continuum fluid behavior impacts on the foundations of contemporary (monovelocity) fluid mechanics. Included therein are the Navier-Stokes-Fourier equations, which are now seen to apply only to incompressible fluids (a fact well-known, empirically, to experimental gas kineticists). The findings of a difference in tracer velocities heralds the introduction into fluid mechanics of a general bipartite theory of fluid mechanics, bivelocity hydrodynamics [Brenner, Int. J. Eng. Sci. 54, 67 (2012)], differing from conventional hydrodynamics in situations entailing compressible flows and reducing to conventional hydrodynamics when the flow is incompressible, while being applicable to both liquids and gases.
Boeker, Peter; Leppert, Jan; Mysliwietz, Bodo; Lammers, Peter Schulze
2013-10-01
The Deans' switch is an effluent switching device based on controlling flows of carrier gas instead of mechanical valves in the analytical flow path. This technique offers high inertness and a wear-free operation. Recently new monolithic microfluidic devices have become available. In these devices the whole flow system is integrated into a small metal device with low thermal mass and leak-tight connections. In contrast to a mechanical valve-based system, a flow-controlled system is more difficult to calculate. Usually the Deans' switch is used to switch one inlet to one of two outlets, by means of two auxiliary flows. However, the Deans' switch can also be used to deliver the GC effluent with a specific split ratio to both outlets. The calculation of the split ratio of the inlet flow to the two outlets is challenging because of the asymmetries of the flow resistances. This is especially the case, if one of the outlets is a vacuum device, such as a mass spectrometer, and the other an atmospheric detector, e.g. a flame ionization detector (FID) or an olfactory (sniffing) port. The capillary flows in gas chromatography are calculated with the Hagen-Poiseuille equation of the laminar, isothermal and compressible flow in circular tubes. The flow resistances in the new microfluidic devices have to be calculated with the corresponding equation for rectangular cross-section microchannels. The Hagen-Poiseuille equation underestimates the flow to a vacuum outlet. A corrected equation originating from the theory of rarefied flows is presented. The calculation of pressures and flows of a Deans' switch based chromatographic system is done by the solution of mass balances. A specific challenge is the consideration of the antidiffusion resistor between the two auxiliary gas lines of the Deans' switch. A full solution for the calculation of the Deans' switch including this restrictor is presented. Results from validation measurements are in good accordance with the developed
Ruban, Anatoly I
This is the first book in a four-part series designed to give a comprehensive and coherent description of Fluid Dynamics, starting with chapters on classical theory suitable for an introductory undergraduate lecture course, and then progressing through more advanced material up to the level of modern research in the field. The present Part 1 consists of four chapters. Chapter 1 begins with a discussion of Continuum Hypothesis, which is followed by an introduction to macroscopic functions, the velocity vector, pressure, density, and enthalpy. We then analyse the forces acting inside a fluid, and deduce the Navier-Stokes equations for incompressible and compressible fluids in Cartesian and curvilinear coordinates. In Chapter 2 we study the properties of a number of flows that are presented by the so-called exact solutions of the Navier-Stokes equations, including the Couette flow between two parallel plates, Hagen-Poiseuille flow through a pipe, and Karman flow above an infinite rotating disk. Chapter 3 is d...
Stenger, M. B.; Hargens, A. R.; Dulchavsky, S. A.; Arbeille, P.; Danielson, R. W.; Ebert, D. J.; Garcia, K. M.; Johnston, S. L.; Laurie, S. S.; Lee, S. M. C.; Liu, J.; Macias, B.; Martin, D. S.; Minkoff, L.; Ploutz-Snyder, R.; Ribeiro, L. C.; Sargsyan, A.; Smith, S. M.
2017-01-01
Introduction. NASA's Human Research Program is focused on addressing health risks associated with long-duration missions on the International Space Station (ISS) and future exploration-class missions beyond low Earth orbit. Visual acuity changes observed after short-duration missions were largely transient, but now more than 50 percent of ISS astronauts have experienced more profound, chronic changes with objective structural findings such as optic disc edema, globe flattening and choroidal folds. These structural and functional changes are referred to as the visual impairment and intracranial pressure (VIIP) syndrome. Development of VIIP symptoms may be related to elevated intracranial pressure (ICP) secondary to spaceflight-induced cephalad fluid shifts, but this hypothesis has not been tested. The purpose of this study is to characterize fluid distribution and compartmentalization associated with long-duration spaceflight and to determine if a relation exists with vision changes and other elements of the VIIP syndrome. We also seek to determine whether the magnitude of fluid shifts during spaceflight, as well as any VIIP-related effects of those shifts, are predicted by the crewmember's pre-flight status and responses to acute hemodynamic manipulations, specifically posture changes and lower body negative pressure. Methods. We will examine a variety of physiologic variables in 10 long-duration ISS crewmembers using the test conditions and timeline presented in the figure below. Measures include: (1) fluid compartmentalization (total body water by D2O, extracellular fluid by NaBr, intracellular fluid by calculation, plasma volume by CO rebreathe, interstitial fluid by calculation); (2) forehead/eyelids, tibia, and calcaneus tissue thickness (by ultrasound); (3) vascular dimensions by ultrasound (jugular veins, cerebral and carotid arteries, vertebral arteries and veins, portal vein); (4) vascular dynamics by MRI (head/neck blood flow, cerebrospinal fluid
Härtel, Andreas; Samin, Sela; van Roij, René
2016-06-01
The ongoing scientific interest in the properties and structure of electric double layers (EDLs) stems from their pivotal role in (super)capacitive energy storage, energy harvesting, and water treatment technologies. Classical density functional theory (DFT) is a promising framework for the study of the in- and out-of-plane structural properties of double layers. Supported by molecular dynamics simulations, we demonstrate the adequate performance of DFT for analyzing charge layering in the EDL perpendicular to the electrodes. We discuss charge storage and capacitance of the EDL and the impact of screening due to dielectric solvents. We further calculate, for the first time, the in-plane structure of the EDL within the framework of DFT. While our out-of-plane results already hint at structural in-plane transitions inside the EDL, which have been observed recently in simulations and experiments, our DFT approach performs poorly in predicting in-plane structure in comparison to simulations. However, our findings isolate fundamental issues in the theoretical description of the EDL within the primitive model and point towards limitations in the performance of DFT in describing the out-of-plane structure of the EDL at high concentrations and potentials.
Swami, Viren; Weis, Laura; Lay, Alixe; Barron, David; Furnham, Adrian
2016-02-28
Conspiracy theories can be treated as both rational narratives of the world as well as outcomes of underlying maladaptive traits. Here, we examined associations between belief in conspiracy theories and individual differences in personality disorders. An Internet-based sample (N=259) completed measures of belief in conspiracy theories and the 25 facets of the Personality Inventory for DSM-5 (PID-5). Preliminary analyses showed no significant differences in belief in conspiracy theories across participant sex, ethnicity, and education. Regression analyses showed that the PID-5 facets of Unusual Beliefs and Experiences and, to a lesser extent, Suspiciousness, significantly predicted belief in conspiracy theories. These findings highlight a role for maladaptive personality traits in understanding belief in conspiracy theories, but require further investigation.
Eringen, A Cemal
1999-01-01
Microcontinuum field theories constitute an extension of classical field theories -- of elastic bodies, deformations, electromagnetism, and the like -- to microscopic spaces and short time scales. Material bodies are here viewed as collections of large numbers of deformable particles, much as each volume element of a fluid in statistical mechanics is viewed as consisting of a large number of small particles for which statistical laws are valid. Classical continuum theories are valid when the characteristic length associated with external forces or stimuli is much larger than any internal scale of the body under consideration. When the characteristic lengths are comparable, however, the response of the individual constituents becomes important, for example, in considering the fluid or elastic properties of blood, porous media, polymers, liquid crystals, slurries, and composite materials. This volume is concerned with the kinematics of microcontinua. It begins with a discussion of strain, stress tensors, balanc...
Refrigerating fluids; Fluides frigorigenes
Energy Technology Data Exchange (ETDEWEB)
Anon.
1999-03-01
Refrigerating fluids are experiencing a real revolution since few years. CFCs with their destructive effect on the ozone layer are now prohibited while HCFCs will be progressively eliminated and replaced by HFCs. However, HFCs can contribute to the increase of the greenhouse effect. The solutions proposed by thermal engineering professionals consist in the confinement of air-conditioning installations (elimination of recurrent leaks) and in the improvement of installations efficiency. HCFC fluids like the R 22 are still widely used in air-conditioning but they are supposed to be replaced by HFC fluids like the R 134a, the R 407C or the R 410A. This short paper gives a brief presentation of these fluids and of their chemical characteristics. (J.S.)
Mechanics of couple-stress fluid coatings
Waxman, A. M.
1982-01-01
The formal development of a theory of viscoelastic surface fluids with bending resistance - their kinematics, dynamics, and rheology are discussed. It is relevant to the mechanics of fluid drops and jets coated by a thin layer of immiscible fluid with rather general rheology. This approach unifies the hydrodynamics of two-dimensional fluids with the mechanics of an elastic shell in the spirit of a Cosserat continuum. There are three distinct facets to the formulation of surface continuum mechanics. Outlined are the important ideas and results associated with each: the kinematics of evolving surface geometries, the conservation laws governing the mechanics of surface continua, and the rheological equations of state governing the surface stress and moment tensors.
Directory of Open Access Journals (Sweden)
Schaller Carlo
2008-12-01
Full Text Available Abstract Background In human neonatal high pressure hydrocephalus (HPHC, diffuse white matter injury and gliosis predispose to poor neuro-developmental outcome. The underlying mechanism for diffuse white matter damage in neonatal HPHC is still unclear. Analogous to inflammatory white matter damage after neonatal hypoxemia/ischemia, we hypothesized that pro-inflammatory cytokines could be involved in neonatal HPHC. If so, early anti-inflammatory therapy could ameliorate white matter damage in HPHC, before irreversible apoptosis has occurred. In HPHC and control neonates, we therefore aimed to compare cerebrospinal fluid (CSF concentrations of IL18, IFNγ and sFasL (interleukin 18, interferon gamma and apoptosis marker soluble-Fas ligand, respectively. Methods In neonatal HPHC (n = 30 and controls (n = 15, we compared CSF concentrations of IL18, IFNγ and sFasL using sandwich ELISA. HPHC was grouped according to etiology: spina bifida aperta (n = 20, aqueduct stenosis (n = 4, and fetal intra-cerebral haemorrhage (n = 6. Neonatal control CSF was derived from otherwise healthy neonates (n = 15, who underwent lumbar puncture for exclusion of meningitis. Results In all three HPHC groups, CSF IL18 concentrations were significantly higher than control values, and the fetal intracranial haemorrhage group was significantly higher than SBA group. Similarly, in all HPHC groups CSF-IFNγ concentrations significantly exceeded the control group. In both HPHC and control neonates, CSF FasL concentrations remained within the range of reference values. Conclusion Independent of the pathogenesis, neonatal HPHC is associated with the activation of the pro-inflammatory cytokines (IL-18 and IFNγ in the CSF, whereas CSF apoptosis biomarkers (sFasL were unchanged. This suggests that anti-inflammatory treatment (in addition to shunting could be helpful to preserve cerebral white matter.
Fiszdon, W
1965-01-01
Fluid Dynamics Transactions, Volume 2 compiles 46 papers on fluid dynamics, a subdiscipline of fluid mechanics that deals with fluid flow. The topics discussed in this book include developments in interference theory for aeronautical applications; diffusion from sources in a turbulent boundary layer; unsteady motion of a finite wing span in a compressible medium; and wall pressure covariance and comparison with experiment. The certain classes of non-stationary axially symmetric flows in magneto-gas-dynamics; description of the phenomenon of secondary flows in curved channels by means of co
Chan, Ho Yin; Lubchenko, Vassiliy
2015-09-01
We set up the problem of finding the transition state for phase nucleation in multi-component fluid mixtures, within the Landau-Ginzburg density functional. We establish an expression for the coordinate-dependent local pressure that applies to mixtures, arbitrary geometries, and certain non-equilibrium configurations. The expression allows one to explicitly evaluate the pressure in spherical geometry, à la van der Waals. Pascal's law is recovered within the Landau-Ginzburg density functional theory, formally analogously to how conservation of energy is recovered in the Lagrangian formulation of mechanics. We establish proper boundary conditions for certain singular functional forms of the bulk free energy density that allow one to obtain droplet solutions with thick walls in essentially closed form. The hydrodynamic modes responsible for mixing near the interface are explicitly identified in the treatment; the composition at the interface is found to depend only weakly on the droplet size. Next we develop a Landau-Ginzburg treatment of the effects of amphiphiles on the surface tension; the amphiphilic action is seen as a violation of Pascal's law. We explicitly obtain the binding potential for the detergent at the interface and the dependence of the down-renormalization of the surface tension on the activity of the detergent. Finally, we argue that the renormalization of the activation barrier for escape from long-lived structures in glassy liquids can be viewed as an action of uniformly seeded, randomly oriented amphiphilic molecules on the interface separating two dissimilar aperiodic structures. This renormalization is also considered as a "wetting" of the interface. The resulting conclusions are consistent with the random first order transition theory.
Chan, Ho Yin; Lubchenko, Vassiliy
2015-09-28
We set up the problem of finding the transition state for phase nucleation in multi-component fluid mixtures, within the Landau-Ginzburg density functional. We establish an expression for the coordinate-dependent local pressure that applies to mixtures, arbitrary geometries, and certain non-equilibrium configurations. The expression allows one to explicitly evaluate the pressure in spherical geometry, à la van der Waals. Pascal's law is recovered within the Landau-Ginzburg density functional theory, formally analogously to how conservation of energy is recovered in the Lagrangian formulation of mechanics. We establish proper boundary conditions for certain singular functional forms of the bulk free energy density that allow one to obtain droplet solutions with thick walls in essentially closed form. The hydrodynamic modes responsible for mixing near the interface are explicitly identified in the treatment; the composition at the interface is found to depend only weakly on the droplet size. Next we develop a Landau-Ginzburg treatment of the effects of amphiphiles on the surface tension; the amphiphilic action is seen as a violation of Pascal's law. We explicitly obtain the binding potential for the detergent at the interface and the dependence of the down-renormalization of the surface tension on the activity of the detergent. Finally, we argue that the renormalization of the activation barrier for escape from long-lived structures in glassy liquids can be viewed as an action of uniformly seeded, randomly oriented amphiphilic molecules on the interface separating two dissimilar aperiodic structures. This renormalization is also considered as a "wetting" of the interface. The resulting conclusions are consistent with the random first order transition theory.
Negative specific heat of black-holes from Fluid-Gravity Correspondence
Bhattacharya, Swastik; Shankaranarayanan, S.
2017-01-01
Black-holes in asymptotically flat space-times have negative specific heat --- they get hotter as they loose energy. A clear statistical mechanical understanding of this has remained a challenge. In this work, we address this issue using fluid-gravity correspondence which aims to associate fluid degrees of freedom to the horizon. Using linear response theory and the teleological nature of event horizon, we show explicitly that the fluctuations of the horizon-fluid lead to negative specific he...
Institute of Scientific and Technical Information of China (English)
Haibin Huang; Xunliang Mai; Xiaohong Ye
2006-01-01
BACKGROUND: Guillain-Barre syndrome (GBS) is an autoimmune disease which is characterized by demyelination of peripheral nerve and nerve root, and inflammatory reaction of lymphocyte and macrophage. Neuroelectrophysiological examination and cerebrospinal fluid (CSF) analysis are of significance for its diagnosis.OBJECTIVE: To study the association of neuroelectrophysiology and cerebrospinal fluid immunoglobulin (CSF-Ig) with pathogenetic conditions of patients with GBS.DESIGN: Case control study.SETTING: Department of Neurology, Shenzhen Municipal Shekou Group Hospital; Department of Neuroelectrophysiology, People's Hospital of Guangdong Province.PARTICIPANTS: A total of 32 GBS patients including 18 males and 14 females who aged from 17 to 72 years were selected as experimental group from the Department of Neurology, People's Hospital of Guangdong Province from January 2004 to December 2005. All cases conformed with GBS diagnostic criteria established by Asbury in 1990 and they were divided into three types according to neurological criteria established by Chinese Neurology and Psychology Journal in 1993: mild, moderate and severe types. Another 30 patients with vascular headache were selected as control group from the same hospital including 14 males and 16 females who aged from 17 to 79 years.METHODS: ① Neuroelectrophysiological examination: Multiple-functional electromyography device provided by Nicolet Company, USA was used to measure nerve conduction velocity (NCV), including motor nerve conduction velocity (MCV) and sensory nerve conduction velocity (SCV); meanwhile, electromyologram (EMG), somatosensory evoked potential (SEP) and electroencephalogram (EEG) were also measured. ② Detection of CSF-Ig: Concentrations of IgG, IgA and IgM were measured with immunofixation electrophoresis. ③ Follow-up: Among 32 GBS patients, 14 cases received follow-up after treatment and the longest follow-up time was 1 year after onset. Among them, 8 cases were reexaminined
Kawasaki, Tadayuki; Uchino, Junji; Shinoda, Toshio; Kawanishi, Hideki
2009-01-01
There has been remarkable medical and technological progress in Japanese dialysis therapy where more than 270 thousand patients had been treated with dialysis by the end of 2007. Clinical engineering technologists have played an important role not only in the safety treatment but also in the technological development of dialysis therapy. It is very important to supply pure dialysis fluid for both the efficacy and the safety of hemodialysis in which high permeable dialysis membranes are used. The Japanese Society for Dialysis Therapy recently issued the standard for bacterial management of fluids for hemodialysis and related therapies according to the International Organization for Standardization (ISO)/DIS 23500. In order to achieve the standard, the management of dialysis water treatment is important as well as the role of clinical engineering technologists in daily dialysis practice. Purification is defined as no contamination by chemical substances and/or microorganisms and its components. The purification consists of the design and the system structure of the water treatment equipment and dialysis fluid-supplying equipment, and the operation and management of the equipment. The guideline aims to show the minimum standard and the management method of the water treatment system and dialysis fluid-supplying equipment in order to perform hemodialysis safely. They should outline safer dialysis by the management of purification of dialysis fluid.
Associated neutrino mixing and neutrino oscillations in left-right electro weak gauge theory
Energy Technology Data Exchange (ETDEWEB)
Parthasarathy, R.
1982-12-01
The question of the associated neutrino mixing is investigated within the frame work of leftright symmetric gauge theory of electro weak interactions. It is shown that the weak leptonic neutral currents are independent of the mixing angle while the charged counterpart crucially depend on them. As the mass of right handed gauge boson becomes very large, the results reduce to those of the standard model, albeit the arbitrarily small mass for the neutrino. With the associated mixing of neutrinos, the muonness changing neutral weak currents are absent at the tree level. A condition for ..nu..sub(..cap alpha..)reversible..nu..sub(..beta..) oscillation is derived as mind(..nu..sub(..cap alpha..))/mind(..nu..sub(..beta..))>msub(..cap alpha..)/msub(..beta..) where ..cap alpha.., ..beta.. stand for e, ..mu.., tau in that order (..cap alpha..not=..beta..). With three neutrino mixing by SO(3) rotation, the present experimental data on neutrino oscillations are satisfactorily explained with the conclusion that ..nu..sub(e) oscilates mostly with ..nu..sub(tau) and vice-versa while ..nu..sub(..mu..) beam suffers very little oscillation. Consequently it is conjectured that most probably Lsub(e) and Lsub(tau) (lepton numbers) are not conversed while Lsub(..mu..) is nearly conserved in weak interaction.
Energy Technology Data Exchange (ETDEWEB)
Lu, Jianbo; Xu, Yanfeng; Wu, Yabo [Liaoning Normal University, Department of Physics, Dalian (China)
2015-10-15
Observations indicate that most of the universal matter is invisible and the gravitational constant G(t) maybe depends on time. A theory of the variational G (VG) is explored in this paper, naturally producing the useful dark components in the universe. We utilize the following observational data: lookback time data, model-independent gamma ray bursts, growth function of matter linear perturbations, type Ia supernovae data with systematic errors, CMB, and BAO, to restrict the unified model (UM) of dark components in VG theory. Using the best-fit values of the parameters with the covariance matrix, constraints on the variation of G are ((G)/(G{sub 0})){sub z=3.5} ≅ 1.0015{sub -0.0075}{sup +0.0071} and ((G)/(G)){sub today} ≅ -0.7252{sub -2.3645}{sup +2.3645} x 10{sup -13} year{sup -1}, with small uncertainties around the constants. The limit on the equation of state of dark matter is w{sub 0dm} = 0.0072{sub -0.0170}{sup +0.0170}, assuming w{sub 0de} = -1 in the unified model, and the dark energy is w{sub 0de} = -0.9986{sub -0.0011}{sup +0.0011}, assuming w{sub 0dm} = 0 a priori. The restrictions on the UM parameters are B{sub s} = 0.7442{sub -0.0132-0.0292}{sup +0.0137+0.0262} and α =0.0002{sub -0.0209-0.0422}{sup +0.0206+0.0441} with 1σ and 2σ confidence level. In addition, the effects of a cosmic string fluid on the unified model in VG theory are investigated. In this case it is found that the Λ CDM (Ω{sub s} = 0, β = 0, and α = 0) is included in this VG-UM model at 1σ confidence level, and larger errors are given: Ω{sub s} = -0.0106{sub -0.0305-0.0509}{sup +0.0312+0.0582} (dimensionless energy density of cosmic string), ((G)/(G{sub 0})){sub z=3.5} ≅ 1.0008{sub -0.0584}{sup +0.0620}, and ((G)/(G)){sub today} ≅ -0.3496{sub -26.3135}{sup +26.3135} x 10{sup -13} year{sup -1}. (orig.)
... carefully. Removing a sample of the fluid through amniocentesis can provide information about the sex, health, and development of the fetus. Images Amniocentesis Amniotic fluid Polyhydramnios Amniotic fluid References Cunningham FG, ...
Weber, David E.; Flemer, David A.; Bundrick, Charles M.
1992-09-01
The structure of a macrobenthic invertebrate community associated with the seagrass, Thalassia testudinum, was evaluated under laboratory and field conditions. The research focused on: (1) the effects of pollution stress from a representative drilling fluid used in off-shore oil and gas operations, and (2) a comparison of responses of the seagrass-invertebrate community in the laboratory and field. A series of 15·3 cm diameter cores of the seagrass-invertebrate community was collected from field sites for establishment and sampling of microcosms and in the sampling of field plots over time. Weekly exposures to drilling fluid were conducted in the laboratory microcosms at a mean total suspended matter concentration of 110·7 mg l -1 (± 17·7 SD), and in field plots by usage of acrylic exposure chambers at a mean concentration of 132·8 mg l -1 (±33·3 SD). Standing crop of T. testudinum was not affected by drilling fluid in the laboratory or field when measured after 6 and 12 week exposure periods. The numbers of macrobenthic invertebrates were suppressed by drilling fluid at both exposure periods in the laboratory, but inhibitory effects were absent in the field. Invertebrate densities in the field were similar among control and treated plots, and were much lower than densities occurring in the laboratory control. In most instances, species richness values were similar in the field and laboratory at the end of each 6 and 12 week period.
Nijland, T.G.; Touret, J.L.R.
2012-01-01
Abstract Granulites constitute a major part of the (lower) continental crust, occurring on a regional scale in many metamorphic belts. Their origin is generally discussed in terms of vapour-absent melting and fluid-assisted dehydration. This last model is notably supported by the occurrence of two i
Mohammad, Sultan; Schleinitz, Miko; Coutinhoa, João A. P.; Freire, Mara G.
2016-01-01
Due to scarce available experimental data, as well as due to the absence of predictive models, the influence of salts on the solubility of ionic liquids (ILs) in water is still poorly understood. To this end, this work addresses the solubility of the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4C1im][NTf2]), at 298.15 K and 0.1 MPa, in aqueous salt solutions (from 0.1 to 1.5 mol kg−1). At salt molalities higher than 0.2 mol kg−1, all salts caused salting-out of [C4C1im][NTf2] from aqueous solution with their strength decreasing in the following order: Al2(SO4)3 > ZnSO4 > K3C6H5O7 > KNaC4H4O6 > K3PO4 > Mg(CH3CO2)2 > K2HPO4 > MgSO4 > KH2PO4 > KCH3CO2. Some of these salts lead however to the salting-in of [C4C1im][NTf2] in aqueous medium at salt molalities lower than 0.20 mol kg−1. To attempt the development of a model able to describe the salt effects, comprising both the salting-in and salting-out phenomena observed, the electrolyte Perturbed-Chain Statistical Associating Fluid Theory (ePC-SAFT) was applied using ion-specific parameters. The gathered experimental data was modelled using ePC-SAFT parameters complemented by fitting a single binary parameter between K+ and the IL-ions to the IL solubility in K3PO4 aqueous solutions. Based on this approach, the description of anion-specific salting-out effects of the remaining potassium salts was found to be in good agreement with experimental data. Remarkably, ePC-SAFT is even able to predict the salting-in effect induced by K2HPO4, based on the single K+/IL-ions binary parameter which was fitted to an exclusively salting-out effect promoted by K3PO4. Finally, ePC-SAFT was applied to predict the influence of other sodium salts on the [C4C1im][NTf2] solubility in water, with experimental data taken from literature, leading to an excellent description of the liquid–liquid phase behaviour. PMID:26575280
Directory of Open Access Journals (Sweden)
Juliana Maria Leite Nóbrega de Moura
2007-08-01
Full Text Available The aim of this work is to present the new applications of membrane technology in fat and oil processing, with emphasis on development and applications of the enzymatic membrane reactor and its association with extraction and purification technology by supercritical fluids (SCF. Combining the extraction by SCFs and the separation by membranes allows the integration of extractions reactions with selective separation by membranes through filtration of the supercritical mixture (SCF + extracted solutes. This association provides important energy savings regarding the SCF recompression costs.
Kobayashi, Hiroyuki; Isohanni, Matti; Jääskeläinen, Erika; Miettunen, Jouko; Veijola, Juha; Haapea, Marianne; Järvelin, Marjo-Riitta; Jones, Peter B; Murray, Graham K
2014-11-01
Neurodevelopmental and neurodegenerative theories may be viewed as incompatible accounts that compete to explain the pathogenesis of schizophrenia. However, it is possible that neurodevelopmental and neurodegenerative processes could both reflect common underlying causal mechanisms. We hypothesized that cognitive dysfunction would gradually deteriorate over time in schizophrenia and the degree of this deterioration in adulthood would be predicted by an infant measure of neurodevelopment. We aimed to examine the association between age of learning to stand in infancy and deterioration of cognitive function in adulthood. Participants were nonpsychotic control subjects (n = 76) and participants with schizophrenia (n = 36) drawn from the Northern Finland 1966 Birth Cohort study. The schizophrenia group showed greater deterioration in abstraction with memory than controls, but there were no differences between schizophrenia and controls in rate of change of other cognitive measures. Age of learning to stand in infancy significantly inversely predicted later deterioration of abstraction with memory in adult schizophrenia (later infant development linked to greater subsequent cognitive deterioration during adulthood), possibly suggesting a link between abnormal neurodevelopmental and neurodegenerative processes in schizophrenia.
Classification of mini-dimmings associated with extreme ultraviolet eruptions by using graph theory
Directory of Open Access Journals (Sweden)
S Bazargan
2016-09-01
Full Text Available Coronal dimmings in both micro and macro scales, can be observed by extreme ultraviolet images, recorded from Solar Dynamics Observatory or Atmospheric Imaging Assembly (SDO/AIA. Mini-dimmings are sometimes associated with wave-like brightening, called coronal mass ejections. Here, the sun full disk images with 171 Å wavelenght, cadence of 2.5, and 0.6 arcsec cell size, were taken on 3 March 2012, then the obtained data were analyzed. Using Zernike Moment and Support Vector Machine (SVM, mini dimmings are detected. 538 active region events, 680 coronal hole events and 723 quiet sun events have been recognized using algorithm. The position, time duration and spatial expansion of these events were computed .The eruptive dimmings have a more spatial development than thermal dimmings after eruptions. This is evident in their graph characteristics length. Then, using graph theory, eruptive and thermal mini-dimmings were classified, with 13% error, for 200 dimmings. 68 dimmings were classified as thermal, and 132 as eruptive. To do this, evolution of graph characteristic length were used.
Directory of Open Access Journals (Sweden)
Harald Lachnit
Full Text Available In four human learning experiments (Pavlovian skin conductance, causal learning, speeded classification task, we evaluated several associative learning theories that assume either an elemental (modified unique cue model and Harris' model or a configural (Pearce's configural theory and an extension of it form of stimulus processing. The experiments used two modified patterning problems (A/B/C+, AB/BC/AC+ vs. ABC-; A+, BC+ vs. ABC-. Pearce's configural theory successfully predicted all of our data reflecting early stimulus processing, while the predictions of the elemental theories were in accord with all of our data reflecting later stages of stimulus processing. Our results suggest that the form of stimulus representation depends on the amount of time available for stimulus processing. Our findings highlight the necessity to investigate stimulus processing during conditioning on a finer time scale than usually done in contemporary research.
Energy Technology Data Exchange (ETDEWEB)
Weber, D.E.; Flemer, D.A.; Bundick, C.M.
1992-01-01
The structure of a macrobenthic invertebrate community associated with the seagrass, Thalassia testudinum, was evaluated under laboratory and field conditions. The research focused on: (1) the effects of pollution stress from a representative drilling fluid used in offshore oil and gas operations, and (2) a comparison of responses of the seagrass-invertebrate community in the laboratory and field. The numbers of macrobenthic invertebrates were suppressed by drilling fluid at both exposure periods in the laboratory, but inhibitory effects were absent in the field. Invertebrate densities in the field were similar among control and treated plots, and were much lower than densities occurring in the laboratory control. In most instances, species richness values were similar in the field and laboratory at the end of each 6 and 12 week period.
Energy Technology Data Exchange (ETDEWEB)
Schaefer, B.; Lambert, S.M.; Song, Y.; Prausnitz, J.M.
1994-10-01
Goal of this work is the extension of a Perturbed-Hard-Sphere-Chain equation of state (PHSC EOS) to systems containing strong polar components. Three different types of association models (ten Brinke/Karasz, SAFI, modified Veytsman) were used to calculate the contribution of specific interactions like hydrogen bonding to thermodynamic quantities. Pure component parameters obtained from regression of temperature dependent density and vapor pressure data allow the prediction of VLE and LLE data. The results of simple fluids and polymer solutions were compared with experimental data. The SAFT and the modified Veytsman extension give similar results for pure fluids and mixtures with components of similar segment size. Differences increase with increasing difference of segment size.
Heidenreich, Sebastian; Ilg, Patrick; Hess, Siegfried
2007-06-01
Boundary effects are investigated for fluids with internal orientational degrees of freedom such as molecular liquids, thermotropic and lyotropic liquid crystals, and polymeric fluids. The orientational degrees of freedom are described by the second rank alignment tensor which is related to the birefringence. We use a standard model to describe the orientational dynamics in the presence of flow, the momentum balance equations, and a constitutive law for the pressure tensor to describe our system. In the spirit of irreversible thermodynamics, boundary conditions are formulated for the mechanical slip velocity and the flux of the alignment. They are set up such that the entropy production at the wall inferred from the entropy flux is positive definite. Even in the absence of a true mechanical slip, the coupling between orientation and flow leads to flow profiles with an apparent slip. This has consequences for the macroscopically measurable effective velocity. In analytical investigations, we consider the simplified case of an isotropic fluid in the Newtonian and stationary flow regime. For special geometries such as plane and cylindrical Couette flow, plane Poiseuille flow, and a flow down an inclined plane, we demonstrate explicitly how the boundary conditions lead to an apparent slip. Furthermore, we discuss the dependence of the effective viscosity and of the effective slip length on the model parameters.
von Rosenvinge, Erik C; Song, Yang; White, James R; Maddox, Cynthia; Blanchard, Thomas; Fricke, W Florian
2013-07-01
The stomach acts as a barrier to ingested microbes, thereby influencing the microbial ecology of the entire gastrointestinal (GI) tract. The stomach microbiota and the role of human host and environmental factors, such as health status or medications, in shaping its composition remain largely unknown. We sought to characterize the bacterial and fungal microbiota in the stomach fluid in order to gain insights into the role of the stomach in GI homeostasis. Gastric fluid was collected from 25 patients undergoing clinically indicated upper endoscopy. DNA isolates were used for PCR amplification of bacterial 16S ribosomal RNA (rRNA) genes and fungal internal transcribed spacers (ITS). RNA isolates were used for 16S rRNA cDNA generation and subsequent PCR amplification. While all stomach fluid samples are dominated by the phyla Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria and Fusobacteria (>99% of sequence reads), the transcriptionally active microbiota shows significant reduction in Actinobacteria (34%) and increase in Campylobacter (444%) (PBacterial but not fungal diversity is reduced by antibiotic treatment (28%; P4 (70%; Pmicrobiota, using bacterial 16S rRNA gene and transcript, and fungal ITS amplicon sequencing and provide evidence for a significant impact of the host immune status on its composition with likely consequences for human health.
de Bilde, Jerissa; Vansteenkiste, Maarten; Lens, Willy
2011-01-01
The present cross-sectional research examined a process underlying the positive association between holding an extended future time perspective (FTP) and learning outcomes through the lens of self-determination theory. High school students and university students (N = 275) participated in the study. It was found that students with an extended FTP…
Reuveni, Yehudit; Werner, Perla
2015-01-01
The purpose of this study was to investigate the factors associated with teenagers' willingness to volunteer with elderly persons using an expanded model of the Theory of Planned Behavior (TPB). Participants consisted of 258 ninth-grade students at a large high school in the northern part of Israel. Participants completed a structured…
Beyond generalized Proca theories
Heisenberg, Lavinia; Tsujikawa, Shinji
2016-01-01
We consider higher-order derivative interactions beyond second-order generalized Proca theories that propagate only the three desired polarizations of a massive vector field besides the two tensor polarizations from gravity. These new interactions follow the similar construction criteria to those arising in the extension of scalar-tensor Horndeski theories to Gleyzes-Langlois-Piazza-Vernizzi (GLPV) theories. On the maximally symmetric space-time, we perform the Hessian and Hamiltonian analysis and show the presence of a second-class constraint that removes the would-be ghost associated with the temporal component of the vector field. Furthermore, we study the behavior of linear perturbations on top of the homogeneous and isotropic cosmological background in the presence of a matter perfect fluid and find the same number of propagating degrees of freedom as in generalized Proca theories. Moreover, we obtain the conditions for the avoidance of ghosts and Laplacian instabilities of tensor, vector, and scalar per...
Physics through the 1990s: Plasmas and fluids
1986-01-01
The volume contains recommendations for programs in, and government support of, plasma and fluid physics. Four broad areas are covered: the physics of fluids, general plasma physics, fusion, and space and astrophysical plasmas. In the first section, the accomplishments of fluid physics and a detailed review of its sub-fields, such as combustion, non-Newtonian fluids, turbulence, aerodynamics, and geophysical fluid dynamics, are described. The general plasma physics section deals with the wide scope of the theoretical concepts involved in plasma research, and with the machines; intense beam systems, collective and laser-driven accelerators, and the associated diagnostics. The section on the fusion plasma research program examines confinement and heating systems, such as Tokamaks, magnetic mirrors, and inertial-confinement systems, and several others. Finally, theory and experiment in space and astrophysical plasma research is detailed, ranging from the laboratory to the solar system and beyond. A glossary is included.
2007-01-01
Periodic motion of three stirrers in a two-dimensional flow can lead to chaotic transport of the surrounding fluid. For certain stirrer motions, the generation of chaos is guaranteed solely by the topology of that motion and continuity of the fluid. Work in this area has focused largely on using physical rods as stirrers, but the theory also applies when the "stirrers" are passive fluid particles. We demonstrate the occurrence of topological chaos for Stokes flow in a two-dimensional lid-driv...
Association of theory of mind with social relations and child's social competence
Directory of Open Access Journals (Sweden)
Nuša Skubic
2012-10-01
Full Text Available The article reviews and evaluates the findings from the research in the field of theory of mind; how the theory of mind is connected to social relationships and how a child's social competence reflects his/hers theory of mind. It points to those factors that contribute most to considerable individual differences among children when developing a theory of mind and it stresses out the reciprocity of effects between child's social understanding and social relations with others. Positive factors for developing a theory of mind are first of all child's early quality experiences about mental states which predict a child's performance on the false belief test later on. Social-economic status, parental behavior and talk (for example appropriate use of mental states and appropriate disciplining of a child and presence of sibling of appropriate age (usually older one with whom a child develops a quality relationship are most important family factors for theory of mind development. The role of peers is most important factor outside the family, emphasized by studies. In accordance with these factors a child develops more or less successfully his/hers social understanding which plays an important part in his/hers daily life. Children with well developed theory of mind can use it in a pro-social way, or it can serve proactive or reactive aggression when children use their understanding of others as a way of manipulating and bullying, especially inside their peer group. Poorly developed theory of mind can prove to be a risk factor especially in a bad family situation, while a well developed theory of mind can play a protective role in child's development. The article points out some of the deficiencies of reviewed studies and proposes options for more complex future research of child's theory of mind.
Sellgren, C M; Kegel, M E; Bergen, S E; Ekman, C J; Olsson, S; Larsson, M; Vawter, M P; Backlund, L; Sullivan, P F; Sklar, P; Smoller, J W; Magnusson, P K E; Hultman, C M; Walther-Jallow, L; Svensson, C I; Lichtenstein, P; Schalling, M; Engberg, G; Erhardt, S; Landén, M
2016-01-01
Elevated cerebrospinal fluid (CSF) levels of the glia-derived N-methyl-D-aspartic acid receptor antagonist kynurenic acid (KYNA) have consistently been implicated in schizophrenia and bipolar disorder. Here, we conducted a genome-wide association study based on CSF KYNA in bipolar disorder and found support for an association with a common variant within 1p21.3. After replication in an independent cohort, we linked this genetic variant—associated with reduced SNX7 expression—to positive psychotic symptoms and executive function deficits in bipolar disorder. A series of post-mortem brain tissue and in vitro experiments suggested SNX7 downregulation to result in a caspase-8-driven activation of interleukin-1β and a subsequent induction of the brain kynurenine pathway. The current study demonstrates the potential of using biomarkers in genetic studies of psychiatric disorders, and may help to identify novel drug targets in bipolar disorder. PMID:26666201
DEFF Research Database (Denmark)
Grenner, Andreas; Tsivintzelis, Ioannis; Economou, Ioannis;
2008-01-01
for the models were taken from literature or estimated in this work. Generalized pure-component parameters were fitted to pure-component vapor-pressure and liquid-density data. For the majority of the mixtures examined, satisfactory results were obtained. For a number of mixtures, different modeling approaches...
Lee, Tien-Rein
2002-06-01
Chinese believe that Feng-shui, Ch'i, Tao, Yin and Yang are major components rooted in Chinese culture. Many people know life has to balance and harmonize with nature and the universe through the Five-essence. Ancient wisdom is successfully interwoven with mankind and the natural world. Elements such as orientation, season, color, sound, facial organs, viscera, stars, and numbers can be associated with life through the Five-essence Theory. Since color is one of the major components of the Five-essence Theory, everything in our life can be associated with colors through a conjoined covering process. Color selection process is part of the interaction between human beings and the universe. Depending on the achievement one is pursuing, the Five- essence Theory model can be treated as an interface between destiny and human beings. This study reports how life is associated with Chinese Five-essence based paradigms. Models were used to explain how Chinese utilize Five-essence Theory to select colors in their daily lives.
Fluid Dynamics and Viscosity in Strongly Correlated Fluids
Schaefer, Thomas
2014-01-01
We review the modern view of fluid dynamics as an effective low energy, long wavelength theory of many body systems at finite temperature. We introduce the notion of a nearly perfect fluid, defined by a ratio $\\eta/s$ of shear viscosity to entropy density of order $\\hbar/k_B$ or less. Nearly perfect fluids exhibit hydrodynamic behavior at all distances down to the microscopic length scale of the fluid. We summarize arguments that suggest that there is fundamental limit to fluidity, and review the current experimental situation with regard to measurements of $\\eta/s$ in strongly coupled quantum fluids.
DEFF Research Database (Denmark)
Andreou, Dimitrios; Saetre, Peter; Werge, Thomas;
2010-01-01
Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in serotonin synthesis. We investigated possible relationships between five TPH1 gene polymorphisms and cerebrospinal fluid (CSF) concentrations of the major serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA), the major dopamine...... metabolite homovanillic acid (HVA), and the major norepinephrine metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) in healthy volunteers (n=132). The G-allele of the TPH1 rs4537731 (A-6526G) polymorphism was associated with 5-HIAA and HVA, but not MHPG concentrations. None of the other four TPH1...
Relativistic viscoelastic fluid mechanics.
Fukuma, Masafumi; Sakatani, Yuho
2011-08-01
A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.
Interfacial instabilities in vibrated fluids
Porter, Jeff; Laverón-Simavilla, Ana; Tinao Perez-Miravete, Ignacio; Fernandez Fraile, Jose Javier
2016-07-01
that leads to splitting (fluid separation). We investigate the interaction of these prominent interfacial instabilities in the absence of gravity, concentrating on harmonically vibrated rectangular containers of fluid. We compare vibroequilibria theory with direct numerical simulations and consider the effect of surfaces waves, which can excite sloshing motion of the vibroequilibria. We systematically investigate the saddle-node bifurcation experienced by a symmetric singly connected vibroequilibria solution, for sufficiently deep containers, as forcing is increased. Beyond this instability, the fluid rapidly separates into (at least) two distinct masses. Pronounced hysteresis is associated with this transition, even in the presence of gravity. The interaction of vibroequilibria and frozen waves is investigated in two-fluid systems. Preparations for a parabolic flight experiment on fluids vibrated at high frequencies are discussed.
Coldren, Faith M; Foteinopoulou, Katerina; Carroll, David L; Laso, Manuel
2008-09-02
The mechanical response, the force-indentation relationship, in normal force spectroscopy measurements carried out on individual polysaccharide encapsulated bacteria is modeled using three increasingly refined approaches that consider the elastic response of the bacterium and cantilever in combination with a fluid (hydrodynamic) model for the polysaccharide layer. For the hydrodynamic description of the polysaccharide layer, several increasingly realistic models are described in detail, together with numerical solution techniques. These models range from one-dimensional, Newtonian, to two-dimensional, axisymmetric, fully viscoelastic (Phan-Thien/Tanner). In all cases, the models rigorously consider the time-dependent rheological-mechanical coupling between the elastic and fluid viscoelastic physical components of the experimental setup. Effects of inherent variability in geometrical and material properties of the bacterium and polysaccharide layer on the measurable response are quantified. A parametric investigation of the force-indentation relationship highlights the importance of accurate knowledge of the rheology of the extracellular polysaccharides. We also draw conclusions about the design and evaluation of force spectroscopy experiments on single encapsulated bacteria. Supported by model calculations, we also point the way to methods of in vivo rheological characterization of the extracellular polysaccharide as a preferable alternative to characterization after its removal from the native environment.
Null fluids: A new viewpoint of Galilean fluids
Banerjee, Nabamita; Dutta, Suvankar; Jain, Akash
2016-05-01
In this article, we study a Galilean fluid with a conserved U (1 ) current up to anomalies. We construct a relativistic system, which we call a null fluid and show that it is in one-to-one correspondence with a Galilean fluid living in one lower dimension. The correspondence is based on light cone reduction, which is known to reduce the Poincaré symmetry of a theory to Galilean in one lower dimension. We show that the proposed null fluid and the corresponding Galilean fluid have exactly same symmetries, thermodynamics, constitutive relations, and equilibrium partition to all orders in the derivative expansion. We also devise a mechanism to introduce U (1 ) anomaly in even dimensional Galilean theories using light cone reduction, and study its effect on the constitutive relations of a Galilean fluid.
Null Fluids - A New Viewpoint of Galilean Fluids
Banerjee, Nabamita; Jain, Akash
2015-01-01
This article is a detailed version of our short letter `On equilibrium partition function for non-relativistic fluid' [arXiv:1505.05677] extended to include an anomalous $U(1)$ symmetry. We construct a relativistic system, which we call null fluid and show that it is in one-to-one correspondence with a Galilean fluid living in one lower dimension. The correspondence is based on light cone reduction, which is known to reduce the Poincare symmetry of a theory to Galilean in one lower dimension. We show that the proposed null fluid and the corresponding Galilean fluid have exactly same symmetries, thermodynamics, constitutive relations, and equilibrium partition to all orders in derivative expansion. We also devise a mechanism to introduce $U(1)$ anomaly in even dimensional Galilean theories using light cone reduction, and study its effect on the constitutive relations of a Galilean Fluid.
Chen, José Enrique; Nurbakhsh, Babak; Layton, Gillian; Bussmann, Markus; Kishen, Anil
2014-08-01
Complexities in root canal anatomy and surface adherent biofilm structures remain as challenges in endodontic disinfection. The ability of an irrigant to penetrate into the apical region of a canal, along with its interaction with the root canal walls, will aid in endodontic disinfection. The aim of this study was to qualitatively examine the irrigation dynamics of syringe irrigation with different needle tip designs (open-ended and closed-ended), apical negative pressure irrigation with the EndoVac® system, and passive ultrasonic-assisted irrigation, using a computational fluid dynamics model. Syringe-based irrigation with a side-vented needle showed a higher wall shear stress than the open-ended but was localised to a small region of the canal wall. The apical negative pressure mode of irrigation generated the lowest wall shear stress, while the passive-ultrasonic irrigation group showed the highest wall shear stress along with the greatest magnitude of velocity.
Kannel, J. W.; Merriman, T. L.; Stockwell, R. D.; Dufrane, K. F.
1983-01-01
The feasibility of measuring elastohydrodynamic (EHD) films as formed with a cryogenic (LN2) fluid is evaluated. Modifications were made to an existing twin disk EHD apparatus to allow for disk lubrication with liquid nitrogen. This disk apparatus is equipped with an X-ray system for measuring the thickness of any lubricant film that is formed between the disks. Several film thickness experiments were conducted with the apparatus which indicate that good lubrication films are filmed with LN2. In addition to the film thickness studies, failure analyses of three bearings were conducted. The HPOTP turbine end bearings had experienced axial loads of 36,000 to 44,000 N (8,000 to 10,000 lb). High continuous radial loads were also experienced, which were most likely caused by thermal growth of the inner race. The resulting high internal loads caused race spalling and ball wear to occur.
DEFF Research Database (Denmark)
Hansen, Klaus Marius
2001-01-01
Fluid interaction, interaction by the user with the system that causes few breakdowns, is essential to many user interfaces. We present two concrete software systems that try to support fluid interaction for different work practices. Furthermore, we present specificity, generality, and minimality...... as design goals for fluid interfaces....
Drazin, Philip
1987-01-01
Outlines the contents of Volume II of "Principia" by Sir Isaac Newton. Reviews the contributions of subsequent scientists to the physics of fluid dynamics. Discusses the treatment of fluid mechanics in physics curricula. Highlights a few of the problems of modern research in fluid dynamics. Shows that problems still remain. (CW)
Institute of Scientific and Technical Information of China (English)
王宏伦; 姚鹏; 梁宵; 吕文涛
2015-01-01
This paper introduces a novel path planning algorithm for Unmanned Aerial Vehicle ( UAV ) based on theory of fluid avoiding obstacles. To the problem of path planning which aims at the global optimum, not only the influence of terrain constraints on path safety but also the performance constraints of UAV should be taken into con-sideration, thus a feasible and smooth path will be planned in the three-dimensional space. The computation com-plexity and the path quality by traditional algorithms are usually unsatisfactory, hence we propose the method in-spired by the phenomenon that water can avoid rocks and reach the destination. The common features between this phenomenon and the path planning problem are extracted and analyzed, and then the mathematical model generali-zing the phenomenon is constructed on the basis of theory of fluid mechanics. By selecting the optimal streamline from the fluid field under the evaluation index, the three-dimensional optimal path under flight and environment con-straints is obtained eventually.
Directory of Open Access Journals (Sweden)
John S K Kauwe
Full Text Available Recent genome-wide association studies of Alzheimer's disease (AD have identified variants in BIN1, CLU, CR1 and PICALM that show replicable association with risk for disease. We have thoroughly sampled common variation in these genes, genotyping 355 variants in over 600 individuals for whom measurements of two AD biomarkers, cerebrospinal fluid (CSF 42 amino acid amyloid beta fragments (Aβ(42 and tau phosphorylated at threonine 181 (ptau(181, have been obtained. Association analyses were performed to determine whether variants in BIN1, CLU, CR1 or PICALM are associated with changes in the CSF levels of these biomarkers. Despite adequate power to detect effects as small as a 1.05 fold difference, we have failed to detect evidence for association between SNPs in these genes and CSF Aβ(42 or ptau(181 levels in our sample. Our results suggest that these variants do not affect risk via a mechanism that results in a strong additive effect on CSF levels of Aβ(42 or ptau(181.
Bradas, James C.; Fennelly, Alphonsus J.; Smalley, Larry L.
1987-01-01
It is shown that a generalized (or 'power law') inflationary phase arises naturally and inevitably in a simple (Bianchi type-I) anisotropic cosmological model in the self-consistent Einstein-Cartan gravitation theory with the improved stress-energy-momentum tensor with the spin density of Ray and Smalley (1982, 1983). This is made explicit by an analytical solution of the field equations of motion of the fluid variables. The inflation is caused by the angular kinetic energy density due to spin. The model further elucidates the relationship between fluid vorticity, the angular velocity of the inertially dragged tetrads, and the precession of the principal axes of the shear ellipsoid. Shear is not effective in damping the inflation.
An Introduction to Fluid Dynamics
Batchelor, G. K.
2000-02-01
First published in 1967, Professor Batchelor's classic work is still one of the foremost texts on fluid dynamics. His careful presentation of the underlying theories of fluids is still timely and applicable, even in these days of almost limitless computer power. This reissue ensures that a new generation of graduate students experiences the elegance of Professor Batchelor's writing.
Devine, Rory T.; White, Naomi; Ensor, Rosie; Hughes, Claire
2016-01-01
The vast majority of studies on theory of mind (ToM) have focused on the preschool years. Extending the developmental scope of ToM research presents opportunities to both reassess theoretical accounts of ToM and test its predictive utility. The twin aims of this longitudinal study were to examine developmental relations between ToM, executive…
Jarvis, P D
2006-01-01
We present a conformal theory of a dissipationless relativistic fluid in 2 space-time dimensions. The theory carries with it a representation of the algebra of 2-$D$ area-preserving diffeomorphisms in the target space of the complex scalar potentials. A complete canonical description is given, and the central charge of the current algebra is calculated. The passage to the quantum theory is discussed in some detail; as a result of operator ordering problems, full quantization at the level of the fields is as yet an open problem.
Deville, E. P.; Prinzhofer, A.; Vacquand, C.; Chavagnac, V.; Monnin, C.; Ceuleneer, G.; Arcilla, C. A.
2009-12-01
We compare the geological environments of sites of emission of natural hydrogen in the Oman ophiolite and the Zambales ophiolite (Luzon, Philippines). The genesis of natural H2 results from the interaction between ultrabasic rocks and aqueous solutions circulating in deep fracture networks, by oxidation of metals (Fe2+, Mn2+) and reduction of water, probably under high temperature conditions. This process generates very reducing conditions capable of destabilizing other molecules (notably reduction of deep CO2 being transformed into CH4 by Fisher-Tropsch type reactions). Nitrogen is also commonly associated to the H2-rich fluids. H2 flows are associated with the expulsion of hyperalkaline waters rich in ions OH- and Ca2+ and characterized by high pH (between 11 and 12). Most alkaline springs are found in the vicinity of major faults and/or lithological discontinuities like the basal thrust plane of the ophiolites and the peridotite-gabbro contact (Moho). Within the fracture networks, gas and water separate probably at shallow depth, i.e. close to the top of the upper aquifer level. Locally high flows of gas migrate vertically through fracture pathways and they are able to inflame spontaneously on the surface. Aqueous fluids tends to migrate laterally in the fracture network toward the creeks where most of the hyperalkaline springs are found. This water circulation induces a chain of diagenetic reactions starting in the fracture systems and continuing at the surface where it leads to the precipitation of calcite, aragonite, brucite and more rarely portlandite. This chain of diagenetic reactions is associated with the capture of the atmospheric CO2 during the precipitation of carbonates.
Huerta, Adrian; Pizio, Orest; Bryk, Pawel; Sokolowski, Stefan
A density functional approach is used to study the adsorption of the four-bonding-site model associating Lennard-Jones fluid in slit-like pores with energetically heterogeneous walls. The fluid-wall potential is qualitatively similar to that invoked by Röcken, P., Somoza, A., Tarazona, P., and Findenegg, G. H., 1999, J. chem. Phys., 108, 8089, i.e. it consists of a homogeneous part that varies in the direction perpendicular to the wall and a periodic part, varying also in one direction parallel to the wall. Both parts are modelled by Lennard-Jones 9,3-type functions. The structure of the adsorbed film is characterized by the local densities of all particles and the densities of the monomers. The phase diagrams are evaluated for several systems characterized by different corrugation of the adsorbing potential. The adsorbing field is strong enough to allow for the layering transition. As well as the formation of the so-called bridge phase that fills the pore space over the most energetic parts of the wall and of capillary condensation, the layering transition is observed within the first layer adjacent to the pore walls. If the adsorbing potential due to each pore wall is shifted in phase by pi/2, the bridge phase is not formed.
Equations of State: From the Ideas of van der Waals to Association Theories
DEFF Research Database (Denmark)
Kontogeorgis, Georgios; Economou, Ioannis G.
2010-01-01
The ideas of van der Waals have resulted to cubic equations of state like Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR) which are widely used in the petroleum and chemical industries. It is often thought that the range of applicability of van der Waals-type models is limited to mixtures...... of compounds relatively similar in size. We employ in this work an approach for investigating the various terms of cubic equations of state by looking at the excess Gibbs energy and activity coefficient expressions which are derived from these equations of state. We illustrate that the results of cubic...... equations of state are sensitive to the mixing and combining rules used. Moreover, it is shown that previously reported deficiencies for size-asymmetric systems are more related to the van der Waals one fluid mixing rules used rather than the functionality of the cubic equation of state itself. Improved...
DEFF Research Database (Denmark)
Liang, Xiaodong; Yan, Wei; Thomsen, Kaj;
2015-01-01
A critical test for the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state (FOS) is the modeling of systems containing petroleum fluid and polar compounds. In this work, two approaches are proposed for the simplified PC-SAFT EOS to obtain the necessary pure component......-SAFT parameter segment diameter. (C) 2015 Elsevier B.V. All rights reserved....
Sarfraz, M.; Yoon, P. H.; Saeed, Sundas; Abbas, G.; Shah, H. A.
2017-01-01
A number of different microinstabilities are known to be responsible for regulating the upper bound of temperature anisotropies in solar wind protons, alpha particles, and electrons. In the present paper, quasilinear kinetic theory is employed to investigate the time variation in electron temperature anisotropies in response to the excitation of parallel electron firehose instability in homogeneous and non-collisional solar wind plasma under the condition of T∥e>T⊥e . By assuming the bi-Maxwellian form of velocity distribution functions, various velocity moments of the particle kinetic equation are taken in order to reduce the theory to macroscopic model in which the wave-particle interaction is incorporated, hence, the macroscopic quasilinear theory. The threshold condition for the parallel electron firehose instability, empirically constructed as a curve in (β∥e,T⊥e/T∥e) phase space, is implicit in the present macroscopic quasilinear calculation. Even though the present calculation excludes the oblique firehose instability, which is known to possess a higher growth rate, the basic methodology may be further extended to include such a mode. Among the findings is that the parallel electron firehose instability dynamically couples the electrons and protons, which implies that this instability may be important for overall solar wind dynamics. The present analysis shows that the macroscopic quasilinear approach may eventually be incorporated in global-kinetic models of the solar wind electrons and ions.
Chiesi, Francesca; Ciancaleoni, Matteo; Galli, Silvia; Primi, Caterina
2012-01-01
This article is aimed at evaluating the possibility that Set I of the Advanced Progressive Matrices (APM-Set I) can be employed to assess fluid ability in a short time frame. The APM-Set I was administered to a sample of 1,389 primary and secondary school students. Confirmatory factor analysis attested to the unidimensionality of the scale. Item…
Why are Fluid Densities So Low in Carbon Nanotubes?
Wang, Gerald J
2014-01-01
The equilibrium density of fluids under nanoconfinement can differ substantially from their bulk density. Using a mean-field approach to describe the energetic landscape near the carbon nanotube (CNT) wall, we obtain analytical results describing the lengthscales associated with the layering observed at the fluid-CNT interface. When combined with molecular simulation results for the fluid density in the layered region, this approach allows us to derive a closed-form prediction for the overall equilibrium fluid density as a function of the CNT radius that is in excellent agreement with molecular dynamics simulations. We also show how aspects of this theory can be extended to describe water confined within CNTs and find good agreement with results from the literature.
Phase Behavior and Percolation Properties of the Patchy Colloidal Fluids in the Random Porous Media.
Kalyuzhnyi, Y V; Holovko, M; Patsahan, T; Cummings, P T
2014-12-18
The lack of a simple analytical description of the hard-sphere fluid in a matrix with hard-core obstacles is limiting progress in the development of thermodynamic perturbation theories for the fluid in random porous media. We propose a simple and highly accurate analytical scheme, which allows us to calculate thermodynamic and percolation properties of a network-forming fluid confined in the random porous media, represented by the hard-sphere fluid and overlapping hard-sphere matrices, respectively. Our scheme is based on the combination of scaled-particle theory, Wertheim's thermodynamic perturbation theory for associating fluids and extension of the Flory-Stockmayer theory for percolation. The liquid-gas phase diagram and percolation threshold line for several versions of the patchy colloidal fluid model confined in a random porous media are calculated and discussed. The method presented enables calculation of the thermodynamic and percolation properties of a large variety of polymerizing and network-forming fluids confined in random porous media.
Raz, Amir; Hines, Terence; Fossella, John; Castro, Daniella
2008-01-01
Paranormal belief and suggestibility seem related. Given our recent findings outlining a putative association between suggestibility and a specific dopaminergic genetic polymorphism, we hypothesized that similar exploratory genetic data may offer supplementary insights into a similar correlation with paranormal belief. With more affordable costs and better technology in the aftermath of the human genome project, genotyping is increasingly ubiquitous. Compelling brain theories guide specific research hypotheses as scientists begin to unravel tentative relationships between phenotype and genotype. In line with a dopaminergic brain theory, we tried to correlate a specific phenotype concerning paranormal belief with a dopaminergic gene (COMT) known for its involvement in prefrontal executive cognition and for a polymorphism that is positively correlated with suggestibility. Although our preliminary findings are inconclusive, the research approach we outline should pave the road to a more scientific account of elucidating paranormal belief.
Eitle, Tamela McNulty; Eitle, David
2015-12-01
This study evaluates the utility of Hagan's power-control theory for explaining substance use behaviors for a sample of American Indian adolescent males and females. Consistent with the theory, we found that patriarchal family form and the affective bond between father and daughter were significant predictors of female substance use behaviors. Compared to results from an analysis of non-Hispanic whites, these results reveal the importance of testing generalist explanations of deviant behavior across racial and ethnic groups. Our findings encourage a more in depth consideration of the gendered nature of work, it's association with socialization and control in American Indian families, and it's impact on gender differences in substance use and delinquent behaviors.
Kundu, Pijush K; Dowling, David R
2011-01-01
Fluid mechanics, the study of how fluids behave and interact under various forces and in various applied situations-whether in the liquid or gaseous state or both-is introduced and comprehensively covered in this widely adopted text. Revised and updated by Dr. David Dowling, Fluid Mechanics, 5e is suitable for both a first or second course in fluid mechanics at the graduate or advanced undergraduate level. Along with more than 100 new figures, the text has been reorganized and consolidated to provide a better flow and more cohesion of topics.Changes made to the
Molecular thermodynamics of nonideal fluids
Lee, Lloyd L
2013-01-01
Molecular Thermodynamics of Nonideal Fluids serves as an introductory presentation for engineers to the concepts and principles behind and the advances in molecular thermodynamics of nonideal fluids. The book covers related topics such as the laws of thermodynamics; entropy; its ensembles; the different properties of the ideal gas; and the structure of liquids. Also covered in the book are topics such as integral equation theories; theories for polar fluids; solution thermodynamics; and molecular dynamics. The text is recommended for engineers who would like to be familiarized with the concept
Basic developments in fluid dynamics
Holt, Maurice
2012-01-01
Basic Developments in Fluid Dynamics, Volume 2 focuses on the developments, approaches, methodologies, reactions, and processes involved in fluid dynamics, including sea motion, wave interactions, and motion of spheres in a viscous fluid.The selection first offers information on inviscid cavity and wake flows and weak-interaction theory of ocean waves. Discussions focus on steady and unsteady cavity flows, radiation balance, theory of weak interactions in random fields, interactions between gravity waves and the atmosphere, and interactions within the ocean. The text then examines low Reynolds
Finite element computational fluid mechanics
Baker, A. J.
1983-01-01
Finite element analysis as applied to the broad spectrum of computational fluid mechanics is analyzed. The finite element solution methodology is derived, developed, and applied directly to the differential equation systems governing classes of problems in fluid mechanics. The heat conduction equation is used to reveal the essence and elegance of finite element theory, including higher order accuracy and convergence. The algorithm is extended to the pervasive nonlinearity of the Navier-Stokes equations. A specific fluid mechanics problem class is analyzed with an even mix of theory and applications, including turbulence closure and the solution of turbulent flows.
Geophysical fluid flow experiment
Broome, B. G.; Fichtl, G.; Fowlis, W.
1979-01-01
The essential fluid flow processes associated with the solar and Jovian atmospheres will be examined in a laboratory experiment scheduled for performance on Spacelab Missions One and Three. The experimental instrumentation required to generate and to record convective fluid flow is described. Details of the optical system configuration, the lens design, and the optical coatings are described. Measurement of thermal gradient fields by schlieren techniques and measurement of fluid flow velocity fields by photochromic dye tracers is achieved with a common optical system which utilizes photographic film for data recording. Generation of the photochromic dye tracers is described, and data annotation of experimental parameters on the film record is discussed.
Transport between two fluids across their mutual flow interface: the streakline approach
Balasuriya, Sanjeeva
2016-01-01
Mixing between two different miscible fluids with a mutual interface must be initiated by fluid transporting across this fluid interface, caused for example by applying an unsteady velocity agitation. In general, there is no necessity for this physical flow barrier between the fluids to be associated with extremal or exponential attraction as might be revealed by applying Lagrangian coherent structures, finite-time Lyapunov exponents or other methods on the fluid velocity. It is shown that streaklines are key to understanding the breaking of the interface under velocity agitations, and a theory for locating the relevant streaklines is presented. Simulations of streaklines in a cross-channel mixer and a perturbed Kirchhoff's elliptic vortex are quantitatively compared to the theoretical results. A methodology for quantifying the unsteady advective transport between the two fluids using streaklines is presented.
Directory of Open Access Journals (Sweden)
Yang XJ
2015-08-01
Full Text Available Xiao-Jun Yang,1,* Yan-Bo Wang,2,3,* Zhi-Wei Zhou,4,* Guo-Wei Wang,2 Xiao-Hong Wang,1 Qing-Fu Liu,1 Shu-Feng Zhou,4 Zhen-Hai Wang2,3 1Department of Intensive Care Unit, 2Neurology Center, General Hospital of Ningxia Medical University, Yinchuan, Ningxia, People’s Republic of China; 3Key Laboratory of Brain Diseases of Ningxia, Yinchuan, Ningxia, People’s Republic of China; 4Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, Tampa, FL, USA *These authors contributed equally to this work Abstract: Ventilator-associated pneumonia (VAP is a life-threatening disease that is associated with high rates of morbidity and likely mortality, placing a heavy burden on an individual and society. Currently available diagnostic and therapeutic approaches for VAP treatment are limited, and the prognosis of VAP is poor. The present study aimed to reveal and discriminate the identification of the full spectrum of the pathogens in patients with VAP using high-throughput sequencing approach and analyze the species richness and complexity via alpha and beta diversity analysis. The bronchoalveolar lavage fluid samples were collected from 27 patients with VAP in intensive care unit. The polymerase chain reaction products of the hypervariable regions of 16S rDNA gene in these 27 samples of VAP were sequenced using the 454 GS FLX system. A total of 103,856 pyrosequencing reads and 638 operational taxonomic units were obtained from these 27 samples. There were four dominant phyla, including Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes. There were 90 different genera, of which 12 genera occurred in over ten different samples. The top five dominant genera were Streptococcus, Acinetobacter, Limnohabitans, Neisseria, and Corynebacterium, and the most widely distributed genera were Streptococcus, Limnohabitans, and Acinetobacter in these 27 samples. Of note, the mixed profile of causative pathogens was observed. Taken
Coupled mode theory approach to depolarization associated with propagation in turbulent media
Crosignani, B.; di Porto, P.; Clifford, Steven F.
1988-06-01
Marcuse's (1974) coupled-mode theory is invoked in the present consideration of the problem of light depolarization in a turbulent atmosphere, in order to allow the evaluation of the depolarization ratio for a plane wave and comparison of its expression with that obtained in the frame of two distinct approaches predicting different behaviors. It is found that both approaches yield the same result when calculated to the same order in both of the relevant smallness parameters, thereby resolving a long-standing controversy.
Ren, Aixia; Zhang, Weiqiang; Yarlagadda, Sunitha; Sinha, Chandrima; Arora, Kavisha; Moon, Chang-Suk; Naren, Anjaparavanda P
2013-04-26
The PDZ (postsynaptic density-95/discs large/zona occludens-1) domain-based interactions play important roles in regulating the expression and function of the cystic fibrosis transmembrane conductance regulator (CFTR). Several PDZ domain-containing proteins (PDZ proteins for short) have been identified as directly or indirectly interacting with the C terminus of CFTR. To better understand the regulation of CFTR processing, we conducted a genetic screen and identified MAST205 (a microtubule-associated serine/threonine kinase with a molecular mass of 205 kDa) as a new CFTR regulator. We found that overexpression of MAST205 increased the expression of CFTR and augmented CFTR-mediated fluid transport in a dose-dependent manner. Conversely, knockdown of MAST205 inhibited CFTR function. The PDZ motif of CFTR is required for the regulatory role of MAST205 in CFTR expression and function. We further demonstrated that MAST205 and the CFTR-associated ligand competed for binding to CFTR, which facilitated the processing of CFTR and consequently up-regulated the expression and function of CFTR at the plasma membrane. More importantly, we found that MAST205 could facilitate the processing of F508del-CFTR mutant and augment its quantity and channel function at the plasma membrane. Taken together, our data suggest that MAST205 plays an important role in regulating CFTR expression and function. Our findings have important clinical implications for treating CFTR-associated diseases such as cystic fibrosis and secretory diarrheas.
Basniev, Kaplan S; Chilingar, George V 0
2012-01-01
The mechanics of fluid flow is a fundamental engineering discipline explaining both natural phenomena and human-induced processes, and a thorough understanding of it is central to the operations of the oil and gas industry. This book, written by some of the world's best-known and respected petroleum engineers, covers the concepts, theories, and applications of the mechanics of fluid flow for the veteran engineer working in the field and the student, alike. It is a must-have for any engineer working in the oil and gas industry.
Fluid-fluid versus fluid-solid demixing in mixtures of parallel hard hypercubes
Lafuente, Luis; Martínez-Ratón, Yuri
2011-02-01
It is well known that increase of the spatial dimensionality enhances the fluid-fluid demixing of a binary mixture of hard hyperspheres, i.e. the demixing occurs for lower mixture size asymmetry as compared to the three-dimensional case. However, according to simulations, in the latter dimension the fluid-fluid demixing is metastable with respect to the fluid-solid transition. According to the results obtained from approximations to the equation of state of hard hyperspheres in higher dimensions, the fluid-fluid demixing might become stable for high enough dimension. However, this conclusion is rather speculative since none of these works have taken into account the stability of the crystalline phase (by a minimization of a given density functional, by spinodal calculations or by MC simulations). Of course, the lack of results is justified by the difficulty of performing density functional calculations or simulations in high dimensions and, in particular, for highly asymmetric binary mixtures. In the present work, we will take advantage of a well tested theoretical tool, namely the fundamental measure density functional theory for parallel hard hypercubes (in the continuum and in the hypercubic lattice). With this, we have calculated the fluid-fluid and fluid-solid spinodals for different spatial dimensions. We have obtained, no matter what the dimensionality, the mixture size asymmetry or the polydispersity (included as a bimodal distribution function centered around the asymmetric edge lengths), that the fluid-fluid critical point is always located above the fluid-solid spinodal. In conclusion, these results point to the existence of demixing between at least one solid phase rich in large particles and one fluid phase rich in small ones, preempting a fluid-fluid demixing, independently of the spatial dimension or the polydispersity.
Effective perfect fluids in cosmology
Energy Technology Data Exchange (ETDEWEB)
Ballesteros, Guillermo [Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Piazza del Viminale 1, I-00184 Rome (Italy); Bellazzini, Brando, E-mail: guillermo.ballesteros@unige.ch, E-mail: brando.bellazzini@pd.infn.it [Dipartimento di Fisica, Università di Padova and INFN, Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy)
2013-04-01
We describe the cosmological dynamics of perfect fluids within the framework of effective field theories. The effective action is a derivative expansion whose terms are selected by the symmetry requirements on the relevant long-distance degrees of freedom, which are identified with comoving coordinates. The perfect fluid is defined by requiring invariance of the action under internal volume-preserving diffeomorphisms and general covariance. At lowest order in derivatives, the dynamics is encoded in a single function of the entropy density that characterizes the properties of the fluid, such as the equation of state and the speed of sound. This framework allows a neat simultaneous description of fluid and metric perturbations. Longitudinal fluid perturbations are closely related to the adiabatic modes, while the transverse modes mix with vector metric perturbations as a consequence of vorticity conservation. This formalism features a large flexibility which can be of practical use for higher order perturbation theory and cosmological parameter estimation.
Rosenfeld, Yaakov
1986-03-01
We study the analytic properties of the hypernetted-chain (HNC) and soft-mean-spherical (SMSA) theories in the asymptotic high-density limit (AHDL). The scaling properties of the inverse power potentials lead to the introduction of the SMSA-Ewald functions, which correspond to the ``overlap-volume'' functions for hard spheres. The HNC and SMSA theories for soft interactions, as well as the Percus-Yevick theory for hard spheres, feature the same AHDL analytic structure of the pair correlation functions, which is dictated by the hard-sphere Ewald functions. The general discussion is supplemented by detailed results for the one-component plasma. Implications to the analysis of the density-functional theory, of dense matter, near its exact Thomas-Fermi limit are pointed out.
Smolyakov, A. I.; Chapurin, O.; Frias, W.; Koshkarov, O.; Romadanov, I.; Tang, T.; Umansky, M.; Raitses, Y.; Kaganovich, I. D.; Lakhin, V. P.
2017-01-01
Partially-magnetized plasmas with magnetized electrons and non-magnetized ions are common in Hall thrusters for electric propulsion and magnetron material processing devices. These plasmas are usually in strongly non-equilibrium state due to presence of crossed electric and magnetic fields, inhomogeneities of plasma density, temperature, magnetic field and beams of accelerated ions. Free energy from these sources make such plasmas prone to various instabilities resulting in turbulence, anomalous transport, and appearance of coherent structures as found in experiments. This paper provides an overview of instabilities that exist in such plasmas. A nonlinear fluid model has been developed for description of the Simon-Hoh, lower-hybrid and ion-sound instabilities. The model also incorporates electron gyroviscosity describing the effects of finite electron temperature. The nonlinear fluid model has been implemented in the BOUT++ framework. The results of nonlinear simulations are presented demonstrating turbulence, anomalous current and tendency toward the formation of coherent structures.
Institute of Scientific and Technical Information of China (English)
2007-01-01
The equation of the state of the hydrogen bonding fluid system of AaDd type is studied by the principle of statistical mechanics. The influences of hydrogen bonds on the equation of state of the system are obtained based on the change in volume due to hydrogen bonds. Moreover,the number density fluc-tuations of both molecules and hydrogen bonds as well as their spatial correlation property are inves-tigated. Furthermore,an equation describing relation between the number density correlation function of "molecules-hydrogen bonds" and that of molecules and hydrogen bonds is derived. As application,taking the van der Waals hydrogen bonding fluid as an example,we considered the effect of hydrogen bonds on its relevant statistical properties.
Rogers, Laura Q; Fogleman, Amanda; Verhulst, Steven; Bhugra, Mudita; Rao, Krishna; Malone, James; Robbs, Randall; Robbins, K Thomas
2015-01-01
Social cognitive theory (SCT) measures related to exercise adherence in head and neck cancer (HNCa) patients were developed. Enrolling 101 HNCa patients, psychometric properties and associations with exercise behavior were examined for barriers self-efficacy, perceived barriers interference, outcome expectations, enjoyment, and goal setting. Cronbach's alpha ranged from.84 to.95; only enjoyment demonstrated limited test-retest reliability. Subscales for barriers self-efficacy (motivational, physical health) and barriers interference (motivational, physical health, time, environment) were identified. Multiple SCT constructs were cross-sectional correlates and prospective predictors of exercise behavior. These measures can improve the application of the SCT to exercise adherence in HNCa patients.
DEFF Research Database (Denmark)
Brorsen, Michael
These lecture notes are intended mainly for the 7th semester course "Fluid Dynamics" offered by the Study Committee on Civil Engineering, Aalborg University.......These lecture notes are intended mainly for the 7th semester course "Fluid Dynamics" offered by the Study Committee on Civil Engineering, Aalborg University....
Wang, Xiaoyan; Hripcsak, George; Friedman, Carol
2009-01-01
Background The availability of up-to-date, executable, evidence-based medical knowledge is essential for many clinical applications, such as pharmacovigilance, but executable knowledge is costly to obtain and update. Automated acquisition of environmental and phenotypic associations in biomedical and clinical documents using text mining has showed some success. The usefulness of the association knowledge is limited, however, due to the fact that the specific relationships between clinical entities remain unknown. In particular, some associations are indirect relations due to interdependencies among the data. Results In this work, we develop methods using mutual information (MI) and its property, the data processing inequality (DPI), to help characterize associations that were generated based on use of natural language processing to encode clinical information in narrative patient records followed by statistical methods. Evaluation based on a random sample consisting of two drugs and two diseases indicates an overall precision of 81%. Conclusion This preliminary study demonstrates that the proposed method is effective for helping to characterize phenotypic and environmental associations obtained from clinical reports. PMID:19761567
Kuška, Martin; Trnka, Radek; Kuběna, Aleš A; Růžička, Jiří
2016-01-01
People construe reality by using words as basic units of meaningful categorization. The present theory-driven study applied the method of a free association task to explore how people express the concepts of the world and the self in words. The respondents were asked to recall any five words relating with the word world. Afterward they were asked to recall any five words relating with the word self. The method of free association provided the respondents with absolute freedom to choose any words they wanted. Such free recall task is suggested as being a relatively direct approach to the respondents' self- and world-related conceptual categories, without enormous rational processing. The results provide us, first, with associative ranges for constructs of the world and the self, where some associative dimensions are defined by semantic polarities in the meanings of peripheral categories (e.g., Nature vs. Culture). Second, our analysis showed that some groups of verbal categories that were associated with the words world and self are central, while others are peripheral with respect to the central position. Third, the analysis of category networks revealed that some categories play the role of a transmitter, mediating the pathway between other categories in the network.
Popolo, Raffaele; Dimaggio, Giancarlo; Luther, Lauren; Vinci, Giancarlo; Salvatore, Giampaolo; Lysaker, Paul H
2016-03-01
Poor insight in schizophrenia is a risk factor for both poor outcomes and treatment adherence. Accordingly, interest in identifying causes of poor insight has increased. This study explored whether theory of mind (ToM) impairments are linked to poor clinical and cognitive insight independent of psychopathology. Participants with schizophrenia (n = 37) and control subjects (n = 40) completed assessments of ToM with the Hinting Task and the Brüne Picture Sequencing Task, clinical insight and psychopathology with the Positive and Negative Syndrome Scale, and cognitive insight with the Beck Cognitive Insight Scale. Results indicated that the schizophrenia group had greater impairments in ToM relative to control subjects. In the schizophrenia group, the Hinting Task performance was related to both cognitive and clinical insight, with only the relationship with cognitive insight persisting after controlling for psychopathology. Picture Sequencing Task performance was related to cognitive insight only. Future research directions and clinical implications are discussed.
ZENO: A Critical Fluid Light Scattering Experiment
1994-01-01
The ZENO experiment flew on the STS-62, it is designed to verify intriguing, but previously untested, theories in fluid physics. These theories attempt to describe dramatic changes in the properties of fluids near the critical temperature at which the vapor and liquid forms co-exist.
Classes and Theories of Trees Associated with a Class Of Linear Orders
DEFF Research Database (Denmark)
Goranko, Valentin; Kellerman, Ruaan
2011-01-01
Given a class of linear order types C, we identify and study several different classes of trees, naturally associated with C in terms of how the paths in those trees are related to the order types belonging to C. We investigate and completely determine the set-theoretic relationships between thes...
An Associative-Activation Theory of Children's and Adults' Memory Illusions
Howe, Mark L.; Wimmer, Marina C.; Gagnon, Nadine; Plumpton, Shannon
2009-01-01
The effects of associative strength and gist relations on rates of children's and adults' true and false memories were examined in three experiments. Children aged 5-11 and university-aged adults participated in a standard Deese/Roediger-McDermott false memory task using DRM and category lists in two experiments and in the third, children…
Yokota, Jun-Ichi; Shimoda, Satoe
2015-05-01
Vertigo and dizziness are common clinical manifestations after traffic accident-associated whiplash injury. Recently, Shinonaga et al. (2001) suggested that more than 80% of patients with whiplash injury complaining of these symptoms showed cerebrospinal (CSF) hypovolemia on radioisotope (RI) cisternography (111In-DTPA). However, neuro-otological studies to investigate the pathophysiological mechanisms underlying these symptoms have been insufficient. In the present study, patients complaining of these symptoms with CSF hypovolemia after traffic accidents were investigated with posturography and electronystagmography (ENG). Fourteen patients (4 men, 10 women; 24-52 yr) were examined with posturography and showed parameters (tracking distance & area) significantly (pafter nystagmus (OKAN) were significantly (p<0.01) reduced (62.64±6.9 SD deg/sec, 60.76±10.74 SD deg/sec, respectively) and frequencies of OKN were reduced (139.7±10.75 SD), while the ocular smooth pursuit was relatively preserved. Magnetic resonance images (sagittal view) of these five patients demonstrated the downward displacement of the cerebellar tonsils and flattening of the pons, which are characteristic features of CSF hypovolemia, called "brain sagging." Our results suggest that brain sagging due to CSF hypovolemia impairs vestibular and vestibulocerebellar functions, which may cause dizziness and vertigo.
Directory of Open Access Journals (Sweden)
Can Zhou
Full Text Available BACKGROUND: Rectal washout can prevent local recurrence after anterior resection of rectal cancer. Few studies have focused particularly on the association between irrigation fluids volume or agents and the risk of local recurrence after anterior resection of rectal cancer. OBJECTIVE: To estimate the association between irrigation fluids types, volumes of rectal washout and risk of local recurrence after anterior resection for cancer. DATA SOURCES: Relevant studies were identified by a search of Medline, Embase, Wiley Online Library, China National Knowledge Infrastructure, Cochrane Oral Health Group Specialized Register, Wanfang databases and Google Website from their inception until October 18,2013. STUDY SELECTION: Studies reporting the association between rectal washout types and volumes and risk of local recurrence after anterior resection for cancer were included. INTERVENTIONS: Eligible studies used rectal washout. Control groups were defined as no washout. STUDY APPRAISAL AND SYNTHESIS METHODS: Random-effects model were used to obtain summary estimates of RR and 95% CI, with Stata version 11 and RevMan 5.2.5 softwares used. The quality of report was appraised in reference to the MINORS item. RESULTS: Of the 919 rectal cancer patients in 8 included studies, a total of 61(6.64% cases of local recurrence were reported, with a pooled RR 0.51 (95%CI = 0.28-0.92, P = 0.03. The RRs 0.37 and 0.39 in normal saline and washout volume (≥ 1500 ml normal saline subgroup, respectively, indicated that rectal washout with normal saline, or ≥ 1500 ml in volume could significantly reduce local recurrence (LR rate (95% CI = 0.17-0.79, P = 0.01; 95% CI = 0.18-0.87, P = 0.02 after anterior resection for cancer. LIMITATION: The included studies were non-randomized observational studies, with diversity of study designs. CONCLUSION: Rectal washout with normal saline alone can reduce the risk of local recurrence in patients with resectable rectal cancer, and
Sharma, Shilpi; Woolfson, Lisa M; Hunter, Simon C
2014-04-01
Despite the well-documented success of cognitive restructuring techniques in the treatment of anxiety disorders, there is still little clarity on which cognitions underpin fear and anxiety in children with high-functioning autism spectrum disorder. This study examined whether certain cognitive appraisals, known to be associated with fear and anxiety in typically developing groups, may help explain these emotions in children with high-functioning autism spectrum disorder. It also investigated relations between these cognitive appraisals and theory of mind. Appraisals, fear and anxiety were assessed using a vignette approach in 22 children with high-functioning autism spectrum disorders and 22 typically developing children. The two groups differed significantly on all four appraisal types. Anxiety was negatively correlated with future expectancy and positively with problem-focused coping potential in the high-functioning autism spectrum disorder group but was not correlated with appraisals in the typically developing group. The two appraisals associated with fear were emotion-focused coping potential (in the high-functioning autism spectrum disorder group only) and self-accountability (in the typically developing group only). Linear regression analysis found that appraisals of emotion-focused coping potential, problem-focused coping potential and future expectancy were significant predictors of theory-of-mind ability in the high-functioning autism spectrum disorders group. These findings indicate that specific, problematic patterns of appraisal may characterise children with high-functioning autism spectrum disorders.
Mizowaki, Takashi; Sasayama, Takashi; Tanaka, Kazuhiro; Mizukawa, Katsu; Takata, Kumi; Nakamizo, Satoshi; Tanaka, Hirotomo; Nagashima, Hiroaki; Nishihara, Masamitsu; Hirose, Takanori; Itoh, Tomoo; Kohmura, Eiji
2015-09-01
Signal transducers and activators of transcription 3 (STAT3) are activated by various cytokines and oncogenes; however, the activity and pathogenesis of STAT3 in diffuse large B cell lymphoma of the central nervous system have not been thoroughly elucidated. We investigated the phosphorylation levels of STAT3 in 40 specimens of primary central nervous system diffuse large B-cell lymphoma (PCNS DLBCL) and analyzed the association between phsopho-STAT3 (pSTAT3) expression and cerebrospinal fluid (CSF) concentration of interleukin-10 (IL-10) or IL-6. Immunohistochemistry and Western blot analysis revealed that most of the specimens in PCNS DLBCL expressed pSTST3 protein, and a strong phosphorylation levels of STAT3 was statistically associated with high CSF IL-10 levels, but not with CSF IL-6 levels. Next, we demonstrated that recombinant IL-10 and CSF containing IL-10 induced the phosphorylation of STAT3 in PCNS DLBCL cells. Furthermore, molecular subtype classified by Hans' algorithm was correlated with pSTAT3 expression levels and CSF IL-10 levels. These results suggest that the STAT3 activity is correlated with CSF IL-10 level, which is a useful marker for STAT3 activity in PCNS DLBCLs.
Fluid dynamics of dilatant fluid
DEFF Research Database (Denmark)
Nakanishi, Hiizu; Nagahiro, Shin-ichiro; Mitarai, Namiko
2012-01-01
A dense mixture of granules and liquid often shows a severe shear thickening and is called a dilatant fluid. We construct a fluid dynamics model for the dilatant fluid by introducing a phenomenological state variable for a local state of dispersed particles. With simple assumptions for an equation...... of the state variable, we demonstrate that the model can describe basic features of the dilatant fluid such as the stress-shear rate curve that represents discontinuous severe shear thickening, hysteresis upon changing shear rate, and instantaneous hardening upon external impact. An analysis of the model...... reveals that the shear thickening fluid shows an instability in a shear flow for some regime and exhibits the shear thickening oscillation (i.e., the oscillatory shear flow alternating between the thickened and the relaxed states). The results of numerical simulations are presented for one- and two...
Chang, Han Soo; Tsuchiya, Tsukasa; Fujisawa, Naoaki; Oya, Soichi; Matsui, Toru
2012-01-01
Despite a number of various hypotheses in the literature, the pathophysiology of syringomyelia is still not well understood. In this article, we report two cases of cervical syringomyelia not associated with Chiari I malformation. Both cases had a septum-like structure in the subarachnoid space on the dorsal side of the cord at the craniovertebral junction. Cardiac-gated phase-contrast cine-mode magnetic resonance imaging (MRI) demonstrated decreased cerebrospinal fluid (CSF) flow on the dorsal side of the spinal cord. Surgical excision of this septum, restoring the CSF flow, resulted in a prompt reduction of the syrinx size in both cases. Findings in these cases contradict the currently prevailing hypothesis of syrinx formation that postulate that the piston-like movement of the cerebellar tonsils enhance the pulsatile CSF flow in the spinal subarachnoid space, driving the CSF into the syrinx through the perivascular space of Virchow and Robin. The authors propose that a mechanism based on the decreased pulsatile CSF flow in the spinal subarachnoid space will be more suitable as a hypothesis in studying the pathophyisiology of syringomyelia. These cases also provide an important lesson in managing the patients with syringomyelia not associated with Chiari I malformation.
Use of Monomer Fraction Data in the Parametrization of Association Theories
DEFF Research Database (Denmark)
Kontogeorgis, Georgios; Tsivintzelis, Ioannis; von Solms, Nicolas;
2010-01-01
“improved” model parameters can be obtained if monomer fraction data are included in the parameter estimation together with vapor pressures and liquid densities. The expression “improved” implies parameters which can represent several pure compound properties as well as monomer fraction data for pure......, liquid densities and monomer fractions of water and alcohols. The 4C scheme is the best choice for water, while for methanol there is small difference between the 2B and 3B association schemes....
Institute of Scientific and Technical Information of China (English)
代世峰; 任德贻; 唐跃刚; 邵龙义; 郝黎明
2002-01-01
The occurrences of associated elements and their genetic factors in the No. 30 coal seam in theZhijin Coalfield were studied using instrumental neutron activation analysis, inductively coupled plasma-atomicemission spectroscopy, and a scanning electron microscope equipped with an energy-dispersive X-ray analyzer.And, a microscope photometer system (Leitz MPV-Ⅲ) was used to observe the characteristics of coal petrology.According to the influence degree by the siliceous low-temperature hydrothermal fluids, the organic matter isdivided into four types: A, B, C, and D of the hydrothermally-altered organic matter (HAOM). The study showsthat the high content of Fe (2.31%) is not from pyrite, but mostly from the siliceous low-temperaturehydrothermal fluids. The occurrences of the associated elements in the four organic matter types are different.The contents of Fe, Si, and Al are decreasing, but S and Cu are increasing in the order of the HAOM-A,HAOM-B, HAOM-C, and HAOM-D. The losing rate of sulfur in organic matter is 0.35% and the content of Fetaken from the low-temperature hydrothermal fluids into the organic matter is 0.794% during the siliceouslow-temperature hydrothermal fluids invading the coal seam. The above facts indicate that the low-temperaturehydrothermal fluids play a crucial role in the re-distributions and occurrences of associated elements in coal.
Directory of Open Access Journals (Sweden)
Paul J. Thibault
2015-07-01
Full Text Available I take Saussure’s distinction between associative and syntagmatic relations in la langue as the starting point for a re-examination of the relationship between memory and language. Saussure’s remarks on this relationship are sparse and fragmentary, cast in terms of the now largely abandoned classical accounts of early neurologists such as Broca and Wernicke, who saw language in the brain as a series of interconnected cortical areas that were presumed to be the repositories of the neurophysiological processes of language function. I draw on Andy Clark’s (1993 idea of ‘associative engines’ to consider how the associative coordination of linguistic items involves (1 the potential for evolution to exploit the gap between gross environmental input to the organism and the input to specific neural networks; and (2 the potential for the language learner qua active agent to create some of its own learning environment. I then look at the ways in which the principle of the associative coordination of diverse series stored in long-term memory makes possible and gives rise to the analysis and segmentation of linguistic syntagms. This development, in turn, makes possible the detecting of the common part of diverse syntagms such that they can be replaced with more schematic ones. The resulting linguistic schema embodies functional constraints on the input data that are available to the learner and thus serve as a pedagogical device, which I call TEACHER FUNCTION. Jason Brown’s (1988 theory of microgenesis together with Deacon’s (1989 account of the dually ‘centrifugal’ and ‘centripetal’ flows of information in the brain provide the basis of a more coherent and complete account of the neural structure of language: The utterance is microgenetically elaborated as it ‘centrifugally’ unfolds over a sequence of neuroanatomical levels (e.g., limbic, generalised neocortex, sensorimotor cortex. On this basis, I articulate some links between
A density functional theory for vapor-liquid interfaces using the PCP-SAFT equation of state
Gross, J.
2009-01-01
A Helmholtz energy functional for inhomogeneous fluid phases based on the perturbed-chain polar statistical associating fluid theory (PCP-SAFT) equation of state is proposed. The model is supplemented with a capillary wave contribution to the surface tension to account for long-wavelength fluctuatio
Directory of Open Access Journals (Sweden)
Schellenberg Gerard D
2010-10-01
Full Text Available Abstract Background Alzheimer's disease (AD is common and highly heritable with many genes and gene variants associated with AD in one or more studies, including APOE ε2/ε3/ε4. However, the genetic backgrounds for normal cognition, mild cognitive impairment (MCI and AD in terms of changes in cerebrospinal fluid (CSF levels of Aβ1-42, T-tau, and P-tau181P, have not been clearly delineated. We carried out a genome-wide association study (GWAS in order to better define the genetic backgrounds to these three states in relation to CSF levels. Methods Subjects were participants in the Alzheimer's Disease Neuroimaging Initiative (ADNI. The GWAS dataset consisted of 818 participants (mainly Caucasian genotyped using the Illumina Human Genome 610 Quad BeadChips. This sample included 410 subjects (119 Normal, 115 MCI and 176 AD with measurements of CSF Aβ1-42, T-tau, and P-tau181P Levels. We used PLINK to find genetic associations with the three CSF biomarker levels. Association of each of the 498,205 SNPs was tested using additive, dominant, and general association models while considering APOE genotype and age. Finally, an effort was made to better identify relevant biochemical pathways for associated genes using the ALIGATOR software. Results We found that there were some associations with APOE genotype although CSF levels were about the same for each subject group; CSF Aβ1-42 levels decreased with APOE gene dose for each subject group. T-tau levels tended to be higher among AD cases than among normal subjects. From adjusted result using APOE genotype and age as covariates, no SNP was associated with CSF levels among AD subjects. CYP19A1 'aromatase' (rs2899472, NCAM2, and multiple SNPs located on chromosome 10 near the ARL5B gene demonstrated the strongest associations with Aβ1-42 in normal subjects. Two genes found to be near the top SNPs, CYP19A1 (rs2899472, p = 1.90 × 10-7 and NCAM2 (rs1022442, p = 2.75 × 10-7 have been reported as genetic
Bernard, Peter S
2015-01-01
This book presents a focused, readable account of the principal physical and mathematical ideas at the heart of fluid dynamics. Graduate students in engineering, applied math, and physics who are taking their first graduate course in fluids will find this book invaluable in providing the background in physics and mathematics necessary to pursue advanced study. The book includes a detailed derivation of the Navier-Stokes and energy equations, followed by many examples of their use in studying the dynamics of fluid flows. Modern tensor analysis is used to simplify the mathematical derivations, thus allowing a clearer view of the physics. Peter Bernard also covers the motivation behind many fundamental concepts such as Bernoulli's equation and the stream function. Many exercises are designed with a view toward using MATLAB or its equivalent to simplify and extend the analysis of fluid motion including developing flow simulations based on techniques described in the book.
Ozawa, Hisashi; Shimokawa, Shinya; Sakuma, Hirofumi
Turbulence is ubiquitous in nature, yet remains an enigma in many respects. Here we investigate dissipative properties of turbulence so as to find out a statistical "law" of turbulence. Two general expressions are derived for a rate of entropy increase due to thermal and viscous dissipation (turbulent dissipation) in a fluid system. It is found with these equations that phenomenological properties of turbulence such as Malkus's suggestion on maximum heat transport in thermal convection as well as Busse's sug- gestion on maximum momentum transport in shear turbulence can rigorously be ex- plained by a unique state in which the rate of entropy increase due to the turbulent dissipation is at a maximum (dS/dt = Max.). It is also shown that the same state cor- responds to the maximum entropy climate suggested by Paltridge. The tendency to increase the rate of entropy increase has also been confirmed by our recent GCM ex- periments. These results suggest the existence of a universal law that manifests itself in the long-term statistics of turbulent fluid systems from laboratory-scale turbulence to planetary-scale circulations. Ref.) Ozawa, H., Shimokawa, S., and Sakuma, H., Phys. Rev. E 64, 026303, 2001.
Salacuse, J. J.; Egelstaff, P. A.
2001-11-01
We describe a method for obtaining the intermediate scattering function I(Q,t) from a computer simulation: it is an extension of our earlier calculation [Salacuse, Denton, and Egelstaff, Phys. Rev. E 53, 2382 (1996)] for the t-->0 limit. We use this approach to obtain I(Q,t) for low Q and t from molecular dynamics (MD) simulations of a model krypton fluid whose atoms interact via a truncated Aziz pair potential, and the results are compared over their range of validity to I(Q,t) determined by the standard MD method and also by a time expansion approach. In its range of validity our approach is much more efficient than the standard MD method; however, it covers a restricted range of t due to the movement of density fluctuations (sound waves) through the simulated fluid which produces an anomaly in the time behavior of I(Q,t). By analyzing I(Q=0,t) the velocity of sound in the simulation is determined, and the results compare favorably with published experimental results for the sound velocity of liquid krypton.
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Melzer Nico
2012-07-01
Full Text Available Abstract Objective The purpose of this paper is to report a patient with otherwise unexplained cerebellar ataxia with serum antibodies against contactin-associated protein-2 (CASPR-2 and provide a detailed description of the composition of cellular infiltrates in the cerebrospinal fluid (CSF compared to the peripheral blood (PB. CASPR-2 antibodies strongly labeling axons of cerebellar granule neurons have recently been identified in sera from nine patients with otherwise unexplained progressive cerebellar ataxia with mild to severe cerebellar atrophy. Design This is a report of a single case. Methods The study methods used were neurologic examination, magnetic resonance imaging, fluorodeoxyglucose positron emisson tomography, lumbar puncture and multicolor flow-cytometry. Results A 23-year-old Caucasian male presented with a two-year history of a progressive cerebellar and brainstem syndrome. Magnetic resonance imaging (MRI showed pronounced cerebellar atrophy, especially of the medial parts of the hemispheres and the vermis. Cerebral fluorodeoxyglucose positron emission tomography (FDG-PET showed pronounced hypometabolism of the whole cerebellum. CASPR-2 antibodies were detected in the serum but not the CSF, and none of the staging and laboratory assessments revealed other causes of progressive cerebellar degeneration. Interestingly, flow-cytometry of the CSF as compared to the PB showed increased fractions of CD138+ plasma cells as well as human leukocyte antigen (HLA-DR+ CD8+ T cells suggesting that both B cells and CD8+ T cells were preferentially recruited to and activated within the CSF- (and putatively central nervous system (CNS- compartment. Conclusion We confirm the association of CASPR-2 serum antibodies with cerebellar ataxia and provide the first evidence for a combined humoral and cellular immune response in this novel antibody-associated inflammatory CNS disease.
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Pereira J.C.R.
2004-01-01
Full Text Available The present study compares the performance of stochastic and fuzzy models for the analysis of the relationship between clinical signs and diagnosis. Data obtained for 153 children concerning diagnosis (pneumonia, other non-pneumonia diseases, absence of disease and seven clinical signs were divided into two samples, one for analysis and other for validation. The former was used to derive relations by multi-discriminant analysis (MDA and by fuzzy max-min compositions (fuzzy, and the latter was used to assess the predictions drawn from each type of relation. MDA and fuzzy were closely similar in terms of prediction, with correct allocation of 75.7 to 78.3% of patients in the validation sample, and displaying only a single instance of disagreement: a patient with low level of toxemia was mistaken as not diseased by MDA and correctly taken as somehow ill by fuzzy. Concerning relations, each method provided different information, each revealing different aspects of the relations between clinical signs and diagnoses. Both methods agreed on pointing X-ray, dyspnea, and auscultation as better related with pneumonia, but only fuzzy was able to detect relations of heart rate, body temperature, toxemia and respiratory rate with pneumonia. Moreover, only fuzzy was able to detect a relationship between heart rate and absence of disease, which allowed the detection of six malnourished children whose diagnoses as healthy are, indeed, disputable. The conclusion is that even though fuzzy sets theory might not improve prediction, it certainly does enhance clinical knowledge since it detects relationships not visible to stochastic models.
Silevitch, M. B.
1981-01-01
A possible mechanism is presented for the generation of large-amplitude temporal fluctuations in the structure of the electron energization region associated with auroral arcs. The mechanism is based on the observation that the auroral arc system resembles a laboratory circuit consisting of the series connection of battery, resistance and a forward biased diode containing collisionless plasma in which large-amplitude relaxation oscillations are sometimes observed to be superimposed on the steady-state current. It is shown that in both the laboratory and auroral systems, in which a localized auroral arc dynamo, the ionosphere and the electron energization region are involved, the oscillations are controlled by the times for ions and electrons to traverse the acceleration region, which also characterize the low- and high-frequency structure of the fluctuating waveform. It is demonstrated that a plausible one-dimensional double-layer model of the auroral arc acceleration region exhibits the dynamic negative resistance necessary for the generation of oscillations by the present mechanism. Finally, consideration is given to two kinds of auroral phenomena which might be associated with the mechanism: the 10-Hz quasi-periodic flickering aurora and 10-Hz modulations in the intensity of electrostatic hydrogen cyclotron waves.
Ellenbogen, Jeffrey M; Hulbert, Justin C; Stickgold, Robert; Dinges, David F; Thompson-Schill, Sharon L
2006-07-11
Mounting behavioral evidence in humans supports the claim that sleep leads to improvements in recently acquired, nondeclarative memories. Examples include motor-sequence learning; visual-discrimination learning; and perceptual learning of a synthetic language. In contrast, there are limited human data supporting a benefit of sleep for declarative (hippocampus-mediated) memory in humans (for review, see). This is particularly surprising given that animal models (e.g.,) and neuroimaging studies (e.g.,) predict that sleep facilitates hippocampus-based memory consolidation. We hypothesized that we could unmask the benefits of sleep by challenging the declarative memory system with competing information (interference). This is the first study to demonstrate that sleep protects declarative memories from subsequent associative interference, and it has important implications for understanding the neurobiology of memory consolidation.
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Qingqin S Li
Full Text Available Proteolytic fragments of amyloid and post-translational modification of tau species in Cerebrospinal fluid (CSF as well as cerebral amyloid deposition are important biomarkers for Alzheimer's Disease. We conducted genome-wide association study to identify genetic factors influencing CSF biomarker level, cerebral amyloid deposition, and disease progression. The genome-wide association study was performed via a meta-analysis of two non-overlapping discovery sample sets to identify genetic variants other than APOE ε4 predictive of the CSF biomarker level (Aβ1-42, t-Tau, p-Tau181P, t-Tau:Aβ1-42 ratio, and p-Tau181P:Aβ1-42 ratio in patients enrolled in the Alzheimer's Disease Neuroimaging Initiative (ADNI study. Loci passing a genome-wide significance threshold of P < 5 x 10-8 were followed-up for replication in an independent sample set. We also performed joint meta-analysis of both discovery sample sets together with the replication sample set. In the discovery phase, we identified variants in FRA10AC1 associated with CSF Aβ1-42 level passing the genome-wide significance threshold (directly genotyped SNV rs10509663 PFE = 1.1 x 10-9, imputed SNV rs116953792 PFE = 3.5 x 10-10, rs116953792 (Pone-sided = 0.04 achieved replication. This association became stronger in the joint meta-analysis (directly genotyped SNV rs10509663 PFE = 1.7 x 10-9, imputed SNV rs116953792 PFE = 7.6 x 10-11. Additionally, we identified locus 15q21 (imputed SNV rs1503351 PFE = 4.0 x 10-8 associated with CSF Aβ1-42 level. No other variants passed the genome-wide significance threshold for other CSF biomarkers in either the discovery sample sets or joint analysis. Gene set enrichment analyses suggested that targeted genes mediated by miR-33, miR-146, and miR-193 were enriched in various GWAS analyses. This finding is particularly important because CSF biomarkers confer disease susceptibility and may be predictive of the likelihood of disease progression in Alzheimer
On petroleum fluid characterization with the PC-SAFT equation of state
DEFF Research Database (Denmark)
Liang, Xiaodong; Yan, Wei; Thomsen, Kaj
2014-01-01
The perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state has shown promising results for describing complex phase behaviors and high pressure properties of various systems. It has been proposed as an alternative to the classical cubic equations of state in the petroleum...
Li, Haiquan; Lee, Younghee; Chen, James L; Rebman, Ellen; Li, Jianrong
2012-01-01
Objective Thousands of complex-disease single-nucleotide polymorphisms (SNPs) have been discovered in genome-wide association studies (GWAS). However, these intragenic SNPs have not been collectively mined to unveil the genetic architecture between complex clinical traits. The authors hypothesize that biological annotations of host genes of trait-associated SNPs may reveal the biomolecular modularity across complex-disease traits and offer insights for drug repositioning. Methods Trait-to-polymorphism (SNPs) associations confirmed in GWAS were used. A novel method to quantify trait–trait similarity anchored in Gene Ontology annotations of human proteins and information theory was developed. The results were then validated with the shortest paths of physical protein interactions between biologically similar traits. Results A network was constructed consisting of 280 significant intertrait similarities among 177 disease traits, which covered 1438 well-validated disease-associated SNPs. Thirty-nine percent of intertrait connections were confirmed by curators, and the following additional studies demonstrated the validity of a proportion of the remainder. On a phenotypic trait level, higher Gene Ontology similarity between proteins correlated with smaller ‘shortest distance’ in protein interaction networks of complexly inherited diseases (Spearman p<2.2×10−16). Further, ‘cancer traits’ were similar to one another, as were ‘metabolic syndrome traits’ (Fisher's exact test p=0.001 and 3.5×10−7, respectively). Conclusion An imputed disease network by information-anchored functional similarity from GWAS trait-associated SNPs is reported. It is also demonstrated that small shortest paths of protein interactions correlate with complex-disease function. Taken together, these findings provide the framework for investigating drug targets with unbiased functional biomolecular networks rather than worn-out single-gene and subjective canonical pathway approaches
Brun-Battistini, D; Sandoval-Villalbazo, A
2016-01-01
Richard C. Tolman analyzed the relation between a temperature gradient and a gravitational field in an equilibrium situation. In 2012, Tolman\\textquoteright s law was generalized to a non-equilibrium situation for a simple dilute relativistic fluid. The result in that scenario, obtained by introducing the gravitational force through the molecular acceleration, couples the heat flux with the metric coefficients and the gradients of the state variables. In the present paper it is shown, by \\textquotedblleft suppressing\\textquotedblright{} the molecular acceleration in Boltzmann\\textquoteright s equation, that a gravitational field drives a heat flux. This procedure corresponds to the description of particle motion through geodesics, in which a Newtonian limit to the Schwarzschild metric is assumed. The effect vanishes in the non-relativistic regime, as evidenced by the direct evaluation of the corresponding limit.
Fingering instability in the flow of a power-law fluid on a rotating disc
Arora, Akash; Doshi, Pankaj
2016-01-01
A computational study of the flow of a non-Newtonian power law fluid on a spinning disc is considered here. The main goal of this work is to examine the effect of non-Newtonian nature of the fluid on the flow development and associated contact line instability. The governing mass and momentum balance equations are simplified using the lubrication theory. The resulting model equation is a fourth order non-linear PDE which describes the spatial and temporal evolutions of film thickness. The movement of the contact line is modeled using a constant angle slip model. To solve this moving boundary problem, a numerical method is developed using a Galerkin/finite element method based approach. The numerical results show that the spreading rate of the fluid strongly depends on power law exponent n. It increases with the increase in the shear thinning character of the fluid (n 1). It is also observed that the capillary ridge becomes sharper with the value of n. In order to examine the stability of these ridges, a linear stability theory is also developed for these power law fluids. The dispersion relationship depicting the growth rate for a given wave number has been reported and compared for different power-law fluids. It is found that the growth rate of the instability decreases as the fluid becomes more shear thinning in nature, whereas it increases for more shear thickening fluids.
Doğan, Gülnihal Emrem; Demir, Turgut; Laloğlu, Esra; Sağlam, Ebru; Aksoy, Hülya; Yildirim, Abdulkadir; Akçay, Fatih
2016-12-22
Fetuin-A is a potent inhibitor of calcium-phosphate precipitation and of the calcification process, therefore it can also be related with dental calculus. Thus, we aimed to investigate a possible relationship between fetuin-A gene polymorphism and the presence of dental calculus. A possible relationship between serum, saliva and gingival crevicular fluid (GCF) levels of fetuin-A was also investigated. Fetuin-A c.742C > T and c.766C > G polymorphisms were investigated in 103 patients with or without dental calculus. Additionally, serum, saliva and GCF fetuin-A levels of patients were compared according to dental calculus presence. A significant difference was not observed in the distribution of the fetuin-A c.742C > T and c.766C > G polymorphisms between patients with or without dental calculus. Saliva and GCF fetuin-A concentrations of patients with dental calculus were statistically higher than those without dental calculus (P=0.001, P=0.036 respectively). According to our results, fetuin-A c.742C > T and c.766C > G polymorphisms were not associated with presence of dental calculus. However, higher GCF and saliva fetuin-A levels were detected in patients with dental calculus than in patients without dental calculus, which may result from an adaptive mechanism to inhibit mineral precipitation and eventually calculus formation.
Application of transport phenomena analysis technique to cerebrospinal fluid.
Lam, C H; Hansen, E A; Hall, W A; Hubel, A
2013-12-01
The study of hydrocephalus and the modeling of cerebrospinal fluid flow have proceeded in the past using mathematical analysis that was very capable of prediction phenomenonologically but not well in physiologic parameters. In this paper, the basis of fluid dynamics at the physiologic state is explained using first established equations of transport phenomenon. Then, microscopic and molecular level techniques of modeling are described using porous media theory and chemical kinetic theory and then applied to cerebrospinal fluid (CSF) dynamics. Using techniques of transport analysis allows the field of cerebrospinal fluid dynamics to approach the level of sophistication of urine and blood transport. Concepts such as intracellular and intercellular pathways, compartmentalization, and tortuosity are associated with quantifiable parameters that are relevant to the anatomy and physiology of cerebrospinal fluid transport. The engineering field of transport phenomenon is rich and steeped in architectural, aeronautical, nautical, and more recently biological history. This paper summarizes and reviews the approaches that have been taken in the field of engineering and applies it to CSF flow.
Zhang, Z.; Shen, K.; Liou, J.; Xu, Z.
2005-12-01
Abundant primary fluid inclusions are recognized in omphacite of ultrahigh-pressure (UHP) eclogites from the main hole of the Chinese Continental Scientific Drilling (CCSD), located at the southern Sulu orogenic belt. The eclogites consist of garnet, omphacite, coesite and rutile. Mineral and fluid inclusions are distributed alternatively and parallel to each other. The solid inclusions occur as needles with a length of 10~100 m and a width of 1~10 m whereas the fluid inclusions occur as tubes with the size varying from less then 3~5 m to greater then 50 m. The mineral inclusions were identified as quartz. Most fluid inclusions contain a gas bubble, a liquid phase and one to several solids. The liquid and gas phases are determined as H2O. The solid phases include halite, quartz and calcite, as well as opaque and unknown minerals. Some small thin-tubed fluid inclusions contain little or no solid and even without gas bubble; they contain dominantly water. The inclusion fluid was estimated to contain components in the system of NaCl-CaCl2-CO2-H2O-SiO2 with possibly trace Fe and Mg. We suggest that these fluid inclusions were conventional primary ones, and trapped during omphacite crystallization; upon decompression they acted as nucleation site for the crystallographically controlled precipitation of quartz from the omphacite matrix. Therefore the omphacite is considered to be one of the major fluid carriers during subduction of continental crust to mantle depths.
Rom, Eldad; Mikulincer, Mario
2003-06-01
Four studies examined attachment-style differences in group-related cognitions and behaviors. In Studies 1-2, participants completed scales on group-related cognitions and emotions. In Studies 3-4, participants were divided into small groups, and their performance in group tasks as well as the cohesion of their group were assessed. Both attachment anxiety and avoidance in close relationships were associated with negative group-related cognitions and emotions. Anxiety was also related to the pursuit of closeness goals and impaired instrumental performance in group tasks. Avoidance was related to the pursuit of distance goals and deficits in socioemotional and instrumental performance. Group cohesion significantly moderated the effects of attachment anxiety. The discussion emphasizes the relevance of attachment theory within group contexts.
O'Shea, Gabrielle; Spence, Susan H; Donovan, Caroline L
2014-01-01
The aim of this study was to investigate whether depressed adolescents differed from non-depressed adolescents in terms of constructs consistent with those that are proposed to underpin interpersonal psychotherapy. In particular, it was hypothesized that compared with non-depressed adolescents, depressed adolescents would demonstrate a greater number of negative life events associated with interpersonal loss and major life transitions, a more insecure attachment style and poorer communication skills, interpersonal relationships and social support. Thirty-one clinically diagnosed depressed adolescents were matched with 31 non-depressed adolescents on age, gender and socio-economic status. The 62 participants were aged between 12 and 19 years and comprised 18 male and 44 female adolescents. On a self-report questionnaire, depressed adolescents reported a greater number of negative interpersonal life events, a less secure attachment style and scored higher on all insecure attachment styles compared with the non-depressed adolescents. In addition, depressed adolescents demonstrated lower levels of social skill (on both adolescent and parent report), a poorer quality of relationship with parents (on both adolescent and parent report) and lower social competence (adolescent report only). Parents of depressed adolescents also reported more negative parental attitudes and behaviours towards their adolescent compared with parents of non-depressed adolescents. Thus, the results of this study are consistent with the constructs underlying interpersonal psychotherapy and suggest their usefulness in the assessment, conceptualization and treatment of adolescent depression. Clinical implications are discussed.
Fluid viscosity under confined conditions
Rudyak, V. Ya.; Belkin, A. A.
2014-12-01
Closed equations of fluid transfer in confined conditions are constructed in this study using ab initio methods of nonequilibrium statistical mechanics. It is shown that the fluid viscosity is not determined by the fluid properties alone, but becomes a property of the "fluid-nanochannel walls" system as a whole. Relations for the tensor of stresses and the interphase force, which specifies the exchange by momentum of fluid molecules with the channel-wall molecules, are derived. It is shown that the coefficient of viscosity is now determined by the sum of three contributions. The first contribution coincides with the expression for the coefficient of the viscosity of fluid in the bulk being specified by the interaction of fluid molecules with each other. The second contribution has the same structure as the first one but is determined by the interaction of fluid molecules with the channel-wall molecules. Finally, the third contribution has no analog in the usual statistical mechanics of transport processes of a simple fluid. It is associated with the correlation of intermolecular forces of the fluid and the channel walls. Thus, it is established that the coefficient of viscosity of fluid in sufficiently small channels will substantially differ from its bulk value.
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Ricardo de Amorim Corrêa
2014-12-01
Full Text Available OBJECTIVE: To compare 28-day mortality rates and clinical outcomes in ICU patients with ventilator-associated pneumonia according to the diagnostic strategy used. METHODS: This was a prospective randomized clinical trial. Of the 73 patients included in the study, 36 and 37 were randomized to undergo BAL or endotracheal aspiration (EA, respectively. Antibiotic therapy was based on guidelines and was adjusted according to the results of quantitative cultures. RESULTS: The 28-day mortality rate was similar in the BAL and EA groups (25.0% and 37.8%, respectively; p = 0.353. There were no differences between the groups regarding the duration of mechanical ventilation, antibiotic therapy, secondary complications, VAP recurrence, or length of ICU and hospital stay. Initial antibiotic therapy was deemed appropriate in 28 (77.8% and 30 (83.3% of the patients in the BAL and EA groups, respectively (p = 0.551. The 28-day mortality rate was not associated with the appropriateness of initial therapy in the BAL and EA groups (appropriate therapy: 35.7% vs. 43.3%; p = 0.553; and inappropriate therapy: 62.5% vs. 50.0%; p = 1.000. Previous use of antibiotics did not affect the culture yield in the EA or BAL group (p = 0.130 and p = 0.484, respectively. CONCLUSIONS: In the context of this study, the management of VAP patients, based on the results of quantitative endotracheal aspirate cultures, led to similar clinical outcomes to those obtained with the results of quantitative BAL fluid cultures.
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Jūratė Savickienė
2016-01-01
Full Text Available Human amniotic-fluid-derived mesenchymal stem cells (AF-MSCs are interesting for their multilineage differentiation potential and wide range of therapeutic applications due to the ease of culture expansion. However, MSCs undergo replicative senescence. So far, the molecular mechanisms that underlie fetal diseases and cell senescence are still poorly understood. Here, we analyzed senescence-associated morphologic, molecular, and epigenetic characteristics during propagation of MSCs derived from AF of normal and fetus-affected pregnancy. AF-MSCs cultures from both cell sources displayed quite similar morphology and expression of specific cell surface (CD44, CD90, and CD105 and stemness (Oct4, Nanog, Sox2, and Rex1 markers but had interindividual variability in proliferation capability and time to reach senescence. Within passages 4 and 8, senescent cultures exhibited typical morphological features, senescence-associated β-galactosidase activity, increased levels of p16, and decreased levels of miR-17 and miR-21 but showed differential expression of p21, p53, and ATM dependently on the onset of cell senescence. These differences correlated with changes in the level of chromatin modifiers (DNMT1 and HDAC1 and polycomb group proteins (EZH2, SUZ12, and BMI1 paralleling with changes in the expression of repressive histone marks (H3K9me3 and H3K27me3 and stemness markers (Oct4, Nanog, Sox2, and Rex1. Therefore epigenetic factors are important for AF-MSCs senescence process that may be related with individuality of donor or a fetus malignancy status.
Savickienė, Jūratė; Baronaitė, Sandra; Zentelytė, Aistė; Treigytė, Gražina
2016-01-01
Human amniotic-fluid-derived mesenchymal stem cells (AF-MSCs) are interesting for their multilineage differentiation potential and wide range of therapeutic applications due to the ease of culture expansion. However, MSCs undergo replicative senescence. So far, the molecular mechanisms that underlie fetal diseases and cell senescence are still poorly understood. Here, we analyzed senescence-associated morphologic, molecular, and epigenetic characteristics during propagation of MSCs derived from AF of normal and fetus-affected pregnancy. AF-MSCs cultures from both cell sources displayed quite similar morphology and expression of specific cell surface (CD44, CD90, and CD105) and stemness (Oct4, Nanog, Sox2, and Rex1) markers but had interindividual variability in proliferation capability and time to reach senescence. Within passages 4 and 8, senescent cultures exhibited typical morphological features, senescence-associated β-galactosidase activity, increased levels of p16, and decreased levels of miR-17 and miR-21 but showed differential expression of p21, p53, and ATM dependently on the onset of cell senescence. These differences correlated with changes in the level of chromatin modifiers (DNMT1 and HDAC1) and polycomb group proteins (EZH2, SUZ12, and BMI1) paralleling with changes in the expression of repressive histone marks (H3K9me3 and H3K27me3) and stemness markers (Oct4, Nanog, Sox2, and Rex1). Therefore epigenetic factors are important for AF-MSCs senescence process that may be related with individuality of donor or a fetus malignancy status. PMID:27803714
Hamiltonian analysis of interacting fluids
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Banerjee, Rabin; Mitra, Arpan Krishna [S. N. Bose National Centre for Basic Sciences, Kolkata (India); Ghosh, Subir [Indian Statistical Institute, Kolkata (India)
2015-05-15
Ideal fluid dynamics is studied as a relativistic field theory with particular stress on its hamiltonian structure. The Schwinger condition, whose integrated version yields the stress tensor conservation, is explicitly verified both in equal-time and light-cone coordinate systems. We also consider the hamiltonian formulation of fluids interacting with an external gauge field. The complementary roles of the canonical (Noether) stress tensor and the symmetric one obtained by metric variation are discussed. (orig.)
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Yamashita Masaomi
2011-06-01
Full Text Available Abstract Background One of the sources of knee pain in osteoarthritis (OA is believed to be related to local chronic inflammation of the knee joints, which involves the production of inflammatory cytokines such as tumor necrosis factor alpha (TNFα, interleukin (IL-6, and nerve growth factor (NGF in the synovial membrane, and these cytokines are believed to promote pathological OA. In the present study, correlations between proinflammatory cytokines in knee synovial fluid and radiographic changes and functional scores and pain scores among OA patients were examined. Methods Synovial fluid was harvested from the knees of 47 consecutive OA patients, and the levels of TNFα, IL-6, and NGF were measured using enzyme-linked immunosorbent assays. Osteoarthritic knees were classified using Kellgren-Lawrence (KL grading (1-4. The Western Ontario and McMaster University Osteoarthritis Index (WOMAC was used to assess self-reported physical function, pain, and stiffness. Results TNFα and IL-6 were detectable in knee synovial, whereas NGF was not. TNFα was not correlated with the KL grade, whereas IL-6 had a significantly negative correlation. We observed differences in the correlations between TNFα and IL-6 with WOMAC scores and their subscales (pain, stiffness, and physical function. TNFα exhibited a significant correlation with the total score and its 3 subscales, whereas IL-6 exhibited a moderately significant negative correlation only with the subscale of stiffness. Conclusions The present study demonstrated that the concentrations of proinflammatory cytokines are correlated with KL grades and WOMAC scores in patients with knee OA. Although TNFα did not have a significant correlation with the radiographic grading, it was significantly associated with the WOMAC score. IL-6 had a significant negative correlation with the KL grading, whereas it had only a weakly significant correlation with the subscore of stiffness. The results suggest that these
Van Pelt, A.
1992-01-01
I. INTRODUCTION AND THEORY This PhD research is mainly concerned with the global phase behaviour, that is calculated from the Simplified-Perturbed-Hard-Chain equation. This equation distinguishes itself from many other equations of state by a sound theoretical background. We enter the field of the t
Bao, Junwei Lucas; Zhang, Xin; Truhlar, Donald G
2016-11-29
Bond dissociation is a fundamental chemical reaction, and the first principles modeling of the kinetics of dissociation reactions with a monotonically increasing potential energy along the dissociation coordinate presents a challenge not only for modern electronic structure methods but also for kinetics theory. In this work, we use multifaceted variable-reaction-coordinate variational transition-state theory (VRC-VTST) to compute the high-pressure limit dissociation rate constant of tetrafluoroethylene (C2F4), in which the potential energies are computed by direct dynamics with the M08-HX exchange correlation functional. To treat the pressure dependence of the unimolecular rate constants, we use the recently developed system-specific quantum Rice-Ramsperger-Kassel theory. The calculations are carried out by direct dynamics using an exchange correlation functional validated against calculations that go beyond coupled-cluster theory with single, double, and triple excitations. Our computed dissociation rate constants agree well with the recent experimental measurements.
OBJECTIVITY REQUIREMENT FOR FLUID DYNAMICS
Institute of Scientific and Technical Information of China (English)
邹文楠
2003-01-01
A new flow theory is established through the objectivity requirement on the fluid dynamics. It was known that inhomogeneous fluid motion gave rise to viscous force while the selection of observers on different space-time points would change such an inhomogeneous character. Therefore, when the viscous force was considered as an objective existence foreign to the selection of observers, the form invariances of viscous force and momentum equation under local rotation transformation required a new dynamic field,namely the vortex field to be introduced. Then the dynamical equations of all flow fields were obtained through constructing the Lagrangian density of fluid system and using the variational approach of energy.
Institute of Scientific and Technical Information of China (English)
梁世强; 张秉坚; 路映红; 胡文暄; 金之钧
2001-01-01
A model for the freely jointed square well chain fluid is developed based on the thermodynamic perturbation theory of Barker Henderson,Zhang and Wertheim.The analytic representations of square well monomer by Zhang are extended to obtain a series of representations for thermodynamic properties of square well chain fluids using the incorporating structural information for square well monomer of Wertheim's TPT1 model.The same work has been done using incorporating structural information for the diatomic square well fluid of TPT D model.The calculated results of compressibility factor,residual internal energy and constant volume heat capacity of 4 mer,8 mer and 16 mer chain fluids are tested against the MC results and a careful comparison between the model from TPT1 and that from TPT D has been made.The former agree with MC results much better than the later,especially for internal energy.To obtain the constant volume heat capacity,NVT MC simulations have been performed.%在 Barker Henderson, Zhang以及 Wertheim 等微扰理论的基础上 ,以方阱势硬球流体为参考体系 ,将 Zhang的解析表达方法与 Wertheim 的链成键自由能的处理方法结合起来 ,推导出自由链接的链状分子流体的 Helmholtz自由能的解析表达式 ,并得到了压缩因子、内能、恒容热容等热力学性质的计算式 .计算结果与 MC(Monte Carlo)模拟结果吻合良好 .对 Zhang的解析表达式与“ TPT D” (二阶 Wertheim微扰理论 )的结合也作了推导和计算 .
Cardillo, Ramona; Garcia, Ricardo Basso; Mammarella, Irene C; Cornoldi, Cesare
2017-03-15
The present study aims to find empirical evidence of deficits in linguistic pragmatic skills and theory of mind (ToM) in children with dyslexia with associated language difficulties or nonverbal learning disabilities (NLD), when compared with a group of typically developing (TD) children matched for age and gender. Our results indicate that children with dyslexia perform less well than TD children in most of the tasks measuring pragmatics of language, and in one of the tasks measuring ToM. In contrast, children with NLD generally performed better than the dyslexia group, and performed significantly worse than the TD children only in a metaphors task based on visual stimuli. A discriminant function analysis confirmed the crucial role of the metaphors subtest and the verbal ToM task in distinguishing between the groups. We concluded that, contrary to a generally-held assumption, children with dyslexia and associated language difficulties may be weaker than children with NLD in linguistic pragmatics and ToM, especially when language is crucially involved. The educational and clinical implications of these findings are discussed.
Dhandapani, Sivashanmugam; Srinivasan, Anirudh
2016-01-01
Triple spinal dysraphism is extremely rare. There are published reports of multiple discrete neural tube defects with intervening normal segments that are explained by the multisite closure theory of primary neurulation, having an association with Chiari malformation Type II consistent with the unified theory of McLone. The authors report on a 1-year-old child with contiguous myelomeningocele and lipomyelomeningocele centered on Type I split cord malformation with Chiari malformation Type II and hydrocephalus. This composite anomaly is probably due to select abnormalities of the neurenteric canal during gastrulation, with a contiguous cascading impact on both dysjunction of the neural tube and closure of the neuropore, resulting in a small posterior fossa, probably bringing the unified theory of McLone closer to the unified theory of Pang.
Pedlosky, Joseph
1979-01-01
The content of this book is based, largely, on the core curriculum in geophys ical fluid dynamics which I and my colleagues in the Department of Geophysical Sciences at The University of Chicago have taught for the past decade. Our purpose in developing a core curriculum was to provide to advanced undergraduates and entering graduate students a coherent and systematic introduction to the theory of geophysical fluid dynamics. The curriculum and the outline of this book were devised to form a sequence of courses of roughly one and a half academic years (five academic quarters) in length. The goal of the sequence is to help the student rapidly advance to the point where independent study and research are practical expectations. It quickly became apparent that several topics (e. g. , some aspects of potential theory) usually thought of as forming the foundations of a fluid-dynamics curriculum were merely classical rather than essential and could be, however sadly, dispensed with for our purposes. At the same ti...
Galilean relativistic fluid mechanics
Ván, P.
2017-01-01
Single-component nonrelativistic dissipative fluids are treated independently of reference frames and flow-frames. First the basic fields and their balances are derived, then the related thermodynamic relations and the entropy production are calculated and the linear constitutive relations are given. The usual basic fields of mass, momentum, energy and their current densities, the heat flux, pressure tensor and diffusion flux are the time- and spacelike components of the third-order mass-momentum-energy density-flux four-tensor. The corresponding Galilean transformation rules of the physical quantities are derived. It is proved that the non-equilibrium thermodynamic frame theory, including the thermostatic Gibbs relation and extensivity condition and also the entropy production, is independent of the reference frame and also the flow-frame of the fluid. The continuity-Fourier-Navier-Stokes equations are obtained almost in the traditional form if the flow of the fluid is fixed to the temperature. This choice of the flow-frame is the thermo-flow. A simple consequence of the theory is that the relation between the total, kinetic and internal energies is a Galilean transformation rule.
Pedlosky, Joseph
1982-01-01
The content of this book is based, largely, on the core curriculum in geophys ical fluid dynamics which land my colleagues in the Department of Geophysical Sciences at The University of Chicago have taught for the past decade. Our purpose in developing a core curriculum was to provide to advanced undergraduates and entering graduate students a coherent and systematic introduction to the theory of geophysical fluid dynamics. The curriculum and the outline of this book were devised to form a sequence of courses of roughly one and a half academic years (five academic quarters) in length. The goal of the sequence is to help the student rapidly advance to the point where independent study and research are practical expectations. It quickly became apparent that several topics (e. g. , some aspects of potential theory) usually thought of as forming the foundations of a fluid-dynamics curriculum were merely classical rather than essential and could be, however sadly, dispensed with for our purposes. At the same tim...
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Payne, J.; Andrews, C. [Fisheries and Oceans Canada, St. John' s, NL (Canada); Guiney, J. [Oceans Ltd., St. John' s, NL (Canada); Whiteway, S. [Jacques Whitford Ltd., St. John' s, NL (Canada)
2006-07-01
This study assessed dose-response relationships for alkane levels in sand sediments spiked with drilling muds that contain an aliphatic hydrocarbon-based synthetic fluid (IPAR). In addition to examining the toxicity levels in 3 sediment bioassays, the impact of drilling wastes on benthic communities in the vicinity of pipelines was also evaluated. The studies were conducted over a 3-year period in order to assess the drilling fluid's potential for producing sediment toxicity. The study also assessed the potential of IPAR to generate anaerobic conditions in sediments over a 12-month period. Pilot studies were conducted to assess false positive levels for bentonite and barite. Results of the tests indicated that sediment toxicity from the use of IPAR drilling fluids was confined to a range of tens of meters from cutting piles located in the immediate vicinity of the drilling rig sites. Results also suggested that the use of Microtox assays should be carefully monitored due to its potential for producing false positives. Distinct anaerobic conditions did not occur after a year of weathering until IPAR concentrations reached the 1000 ppm range. It was concluded that high concentrations of barite additions were not toxic to capelin, snowcrab larvae, or planktonic jellyfish after a period of 24 hours. No mortalities were observed for flounders force-fed high concentrations of barite at weekly intervals. 4 refs.
Feenders, Gesa; Liedvogel, Miriam; Rivas, Miriam; Zapka, Manuela; Horita, Haruhito; Hara, Erina; Wada, Kazuhiro; Mouritsen, Henrik; Jarvis, Erich D
2008-03-12
Vocal learning is a critical behavioral substrate for spoken human language. It is a rare trait found in three distantly related groups of birds-songbirds, hummingbirds, and parrots. These avian groups have remarkably similar systems of cerebral vocal nuclei for the control of learned vocalizations that are not found in their more closely related vocal non-learning relatives. These findings led to the hypothesis that brain pathways for vocal learning in different groups evolved independently from a common ancestor but under pre-existing constraints. Here, we suggest one constraint, a pre-existing system for movement control. Using behavioral molecular mapping, we discovered that in songbirds, parrots, and hummingbirds, all cerebral vocal learning nuclei are adjacent to discrete brain areas active during limb and body movements. Similar to the relationships between vocal nuclei activation and singing, activation in the adjacent areas correlated with the amount of movement performed and was independent of auditory and visual input. These same movement-associated brain areas were also present in female songbirds that do not learn vocalizations and have atrophied cerebral vocal nuclei, and in ring doves that are vocal non-learners and do not have cerebral vocal nuclei. A compilation of previous neural tracing experiments in songbirds suggests that the movement-associated areas are connected in a network that is in parallel with the adjacent vocal learning system. This study is the first global mapping that we are aware for movement-associated areas of the avian cerebrum and it indicates that brain systems that control vocal learning in distantly related birds are directly adjacent to brain systems involved in movement control. Based upon these findings, we propose a motor theory for the origin of vocal learning, this being that the brain areas specialized for vocal learning in vocal learners evolved as a specialization of a pre-existing motor pathway that controls
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Gesa Feenders
Full Text Available Vocal learning is a critical behavioral substrate for spoken human language. It is a rare trait found in three distantly related groups of birds-songbirds, hummingbirds, and parrots. These avian groups have remarkably similar systems of cerebral vocal nuclei for the control of learned vocalizations that are not found in their more closely related vocal non-learning relatives. These findings led to the hypothesis that brain pathways for vocal learning in different groups evolved independently from a common ancestor but under pre-existing constraints. Here, we suggest one constraint, a pre-existing system for movement control. Using behavioral molecular mapping, we discovered that in songbirds, parrots, and hummingbirds, all cerebral vocal learning nuclei are adjacent to discrete brain areas active during limb and body movements. Similar to the relationships between vocal nuclei activation and singing, activation in the adjacent areas correlated with the amount of movement performed and was independent of auditory and visual input. These same movement-associated brain areas were also present in female songbirds that do not learn vocalizations and have atrophied cerebral vocal nuclei, and in ring doves that are vocal non-learners and do not have cerebral vocal nuclei. A compilation of previous neural tracing experiments in songbirds suggests that the movement-associated areas are connected in a network that is in parallel with the adjacent vocal learning system. This study is the first global mapping that we are aware for movement-associated areas of the avian cerebrum and it indicates that brain systems that control vocal learning in distantly related birds are directly adjacent to brain systems involved in movement control. Based upon these findings, we propose a motor theory for the origin of vocal learning, this being that the brain areas specialized for vocal learning in vocal learners evolved as a specialization of a pre-existing motor
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Annisa N. Insany
2015-06-01
Full Text Available High prevalence of self medication with antibiotics can increase the probability of irrational use of antibiotics which may lead antibiotics resistance. Thus, shifting of behavior is required to minimize the irrational use of antibiotics. This study was aimed to determine the association between public perceived value and self-medication with antibiotics which can be used to develop an intervention model in order to reduce the practice of self-medication with antibiotics. An observational study was conducted during the period of November–December 2014.The subjects were patients who visit primary health care facilities in Bandung. A structured-interview that has been validated was used to investigate the association between perceived value and self-medication behavior based on the Health Belief Model theory (perceived susceptibility, benefits, barrier, and cues to action. Approximately 506 respondents were drawn randomly from 43 community healthcare centers and 8 pharmacies. Data was analyzed by using descriptive statistics and logistic regression (CI 95%, α = 5%. Validity and reliability of the questionnaire were shown with a correlation coefficient of >0.3 and a cronbach-alpha value of 0.719, respectively. We found that 29.45% of respondents practiced self-medication with antibiotics over the last six months. Additionally, there was no significant association between the perceived susceptibility, benefits, barrier, and cues to action with self-medication behavior (p>0.05. Easiness to access antibiotics without prescription was presumed as a factor that contribute to self-medication with antibiotics, therefore strict regulation in antibiotics use is very needed as a basic intervention to decrease self-medication with antibiotic.
Hamiltonian fluid closures of the Vlasov-Amp{\\`e}re equations: from water-bags to N moment models
Perin, M; Morrison, P J; Tassi, E
2015-01-01
Moment closures of the Vlasov-Amp{\\`e}re system, whereby higher moments are represented as functions of lower moments with the constraint that the resulting fluid system remains Hamiltonian, are investigated by using water-bag theory. The link between the water-bag formalism and fluid models that involve density, fluid velocity, pressure and higher moments is established by introducing suitable thermodynamic variables. The cases of one, two and three water-bags are treated and their Hamiltonian structures are provided. In each case, we give the associated fluid closures and we discuss their Casimir invariants. We show how the method can be extended to an arbitrary number of fields, i.e., an arbitrary number of water-bags and associated moments. The thermodynamic interpretation of the resulting models is discussed. Finally, a general procedure to derive Hamiltonian N-field fluid models is proposed.
DEFF Research Database (Denmark)
Kallestrup, M; Møller, Holger Jon; Tankisi, H;
2015-01-01
using an enzyme-linked immunosorbent assay. RESULTS: Soluble CD163 levels were significantly higher in the cerebrospinal fluid and serum of the participants with Type 2 diabetes compared with the control participants [cerebrospinal fluid: median (range) 107 (70-190) vs 84 (54-115) μg/l, P ....01 and serum: 2305 (920-7060) vs 1420 (780-2740) μg/l, P higher levels of soluble CD163 in the cerebrospinal fluid...... nerve function. Higher levels of soluble CD163 in people with diabetic polyneuropathy suggest that inflammation plays a role in the development of neural impairment. The relationship between cerebrospinal fluid soluble CD163 level and peripheral nerve conduction indicates that soluble CD163 may...
Oliveira, Michelli F.; Chaillon, Antoine; Nakazawa, Masato; Vargas, Milenka; Strain, Matthew C.; Morris, Sheldon; Little, Susan J.; Smith, Davey M.; Gianella, Sara
2017-01-01
Even when antiretroviral therapy (ART) is started early after infection, HIV DNA might persist in the central nervous system (CNS), possibly contributing to inflammation, brain damage and neurocognitive impairment. Paired blood and cerebrospinal fluid (CSF) were collected from 16 HIV-infected individuals on suppressive ART: 9 participants started ART 14 months after EDI (“late ART”). For each participant, neurocognitive functioning was measured by Global Deficit Score (GDS). HIV DNA levels were measured in peripheral blood mononuclear cells (PBMCs) and CSF cell pellets by droplet digital (dd)PCR. Soluble markers of inflammation (sCD163, IL-6, MCP-1, TNF-α) and neuronal damage (neurofilament light [NFL]) were measured in blood and CSF supernatant by immunoassays. HIV-1 partial C2V3 env deep sequencing data (Roche 454) were obtained for 8 paired PBMC and CSF specimens and used for phylogenetic and compartmentalization analysis. Median exposure to ART at the time of sampling was 2.6 years (IQR: 2.2–3.7) and did not differ between groups. We observed that early ART was significantly associated with lower molecular diversity of HIV DNA in CSF (p<0.05), and lower IL-6 levels in CSF (p = 0.02), but no difference for GDS, NFL, or HIV DNA detectability compared to late ART. Compartmentalization of HIV DNA populations between CSF and blood was detected in 6 out of 8 participants with available paired HIV DNA sequences (2 from early and 4 from late ART group). Phylogenetic analysis confirmed the presence of monophyletic HIV DNA populations within the CSF in 7 participants, and the same population was repeatedly sampled over a 5 months period in one participant with longitudinal sampling. Such compartmentalized provirus in the CNS needs to be considered for the design of future eradication strategies and might contribute to the neuropathogenesis of HIV. PMID:28046096
On Radiative Fluids in Anisotropic Spacetimes
Shogin, Dmitry
2016-01-01
We apply the second-order Israel-Stewart theory of relativistic fluid- and thermodynamics to a physically realistic model of a radiative fluid in a simple anisotropic cosmological background. We investigate the asymptotic future of the resulting cosmological model and review the role of the dissipative phenomena in the early Universe. We demonstrate that the transport properties of the fluid alone, if described appropriately, do not explain the presently observed accelerated expansion of the Universe. Also, we show that, in constrast to the mathematical fluid models widely used before, the radiative fluid does approach local thermal equilibrium at late times, although very slowly, due to the cosmological expansion.