NASA Astrophysics Data System (ADS)
Sanz Prat, A.; Lu, C.; Cirpka, O. A.
2014-12-01
Travel-time based models are presented as an alternative to traditional spatially explicit models to solve nonlinear reactive-transport problems. The main advantage of the travel-time approach is that it does not require multi-dimensional characterization of physical and chemical parameters, and transport is one-dimensional. Spatial dimensions are replaced by groundwater travel time, defined as the time required by a water particle to reach an observation point or the outflow boundary, respectively. The fundamental hypothesis is that locations of the same groundwater age exhibit the same reactive-species concentrations. This is true in strictly advective-reactive transport in steady-state flows if the coefficients of reactions are uniform and the concentration is uniform over the inflow boundary. We hypothesize that the assumption still holds when adding some dispersion in coupled flow and transport dynamics. We compare a two-dimensional, spatially explicit, bioreactive, advective-dispersive transport model, considered as "virtual truth", with three 1-D travel-time based models which differ by the conceptualization of longitudinal dispersion: (i) neglecting dispersive mixing altogether, (ii) introducing a local-scale longitudinal dispersivity constant in time and space, and (iii) using an effective longitudinal dispersivity that increases linearly with distance. We consider biodegradation of organic matter catalyzed by non-competitive inhibitive microbial populations. The simulated inflow contains oxygen, nitrate, and DOC. The domain contains growing aerobic and denitrifying bacteria, the latter being inhibited by oxygen. This system is computed in 1-D, and in 2-D heterogeneous domains. We conclude that the conceptualization of nonlinear bioreactive transport in complex multi-dimensional domains by quasi 1-D travel-time models is valid for steady-state flow if the reactants are introduced over a wide cross-section, flow is at quasi-steady state, and dispersive
On the validity of travel-time based nonlinear bioreactive transport models in steady-state flow
NASA Astrophysics Data System (ADS)
Sanz-Prat, Alicia; Lu, Chuanhe; Finkel, Michael; Cirpka, Olaf A.
2015-04-01
Travel-time based models simplify the description of reactive transport by replacing the spatial coordinates with the groundwater travel time, posing a quasi one-dimensional (1-D) problem and potentially rendering the determination of multidimensional parameter fields unnecessary. While the approach is exact for strictly advective transport in steady-state flow if the reactive properties of the porous medium are uniform, its validity is unclear when local-scale mixing affects the reactive behavior. We compare a two-dimensional (2-D), spatially explicit, bioreactive, advective-dispersive transport model, considered as "virtual truth", with three 1-D travel-time based models which differ in the conceptualization of longitudinal dispersion: (i) neglecting dispersive mixing altogether, (ii) introducing a local-scale longitudinal dispersivity constant in time and space, and (iii) using an effective longitudinal dispersivity that increases linearly with distance. The reactive system considers biodegradation of dissolved organic carbon, which is introduced into a hydraulically heterogeneous domain together with oxygen and nitrate. Aerobic and denitrifying bacteria use the energy of the microbial transformations for growth. We analyze six scenarios differing in the variance of log-hydraulic conductivity and in the inflow boundary conditions (constant versus time-varying concentration). The concentrations of the 1-D models are mapped to the 2-D domain by means of the kinematic (for case i), and mean groundwater age (for cases ii & iii), respectively. The comparison between concentrations of the "virtual truth" and the 1-D approaches indicates extremely good agreement when using an effective, linearly increasing longitudinal dispersivity in the majority of the scenarios, while the other two 1-D approaches reproduce at least the concentration tendencies well. At late times, all 1-D models give valid approximations of two-dimensional transport. We conclude that the
On the validity of travel-time based nonlinear bioreactive transport models in steady-state flow.
Sanz-Prat, Alicia; Lu, Chuanhe; Finkel, Michael; Cirpka, Olaf A
2015-01-01
Travel-time based models simplify the description of reactive transport by replacing the spatial coordinates with the groundwater travel time, posing a quasi one-dimensional (1-D) problem and potentially rendering the determination of multidimensional parameter fields unnecessary. While the approach is exact for strictly advective transport in steady-state flow if the reactive properties of the porous medium are uniform, its validity is unclear when local-scale mixing affects the reactive behavior. We compare a two-dimensional (2-D), spatially explicit, bioreactive, advective-dispersive transport model, considered as "virtual truth", with three 1-D travel-time based models which differ in the conceptualization of longitudinal dispersion: (i) neglecting dispersive mixing altogether, (ii) introducing a local-scale longitudinal dispersivity constant in time and space, and (iii) using an effective longitudinal dispersivity that increases linearly with distance. The reactive system considers biodegradation of dissolved organic carbon, which is introduced into a hydraulically heterogeneous domain together with oxygen and nitrate. Aerobic and denitrifying bacteria use the energy of the microbial transformations for growth. We analyze six scenarios differing in the variance of log-hydraulic conductivity and in the inflow boundary conditions (constant versus time-varying concentration). The concentrations of the 1-D models are mapped to the 2-D domain by means of the kinematic (for case i), and mean groundwater age (for cases ii & iii), respectively. The comparison between concentrations of the "virtual truth" and the 1-D approaches indicates extremely good agreement when using an effective, linearly increasing longitudinal dispersivity in the majority of the scenarios, while the other two 1-D approaches reproduce at least the concentration tendencies well. At late times, all 1-D models give valid approximations of two-dimensional transport. We conclude that the
Spin models as microfoundation of macroscopic market models
NASA Astrophysics Data System (ADS)
Krause, Sebastian M.; Bornholdt, Stefan
2013-09-01
Macroscopic price evolution models are commonly used for investment strategies. There are first promising achievements in defining microscopic agent based models for the same purpose. Microscopic models allow a deeper understanding of mechanisms in the market than the purely phenomenological macroscopic models, and thus bear the chance for better models for market regulation. However microscopic models and macroscopic models are commonly studied separately. Here, we exemplify a unified view of a microscopic and a macroscopic market model in a case study, deducing a macroscopic Langevin equation from a microscopic spin market model closely related to the Ising model. The interplay of the microscopic and the macroscopic view allows for a better understanding and adjustment of the microscopic model, as well, and may guide the construction of agent based market models as basis of macroscopic models.
Macroscopic Modeling of Polymer-Electrolyte Membranes
Weber, A.Z.; Newman, J.
2007-04-01
In this chapter, the various approaches for the macroscopic modeling of transport phenomena in polymer-electrolyte membranes are discussed. This includes general background and modeling methodologies, as well as exploration of the governing equations and some membrane-related topic of interest.
Adsorption modeling for macroscopic contaminant dispersal analysis
Axley, J.W.
1990-05-01
Two families of macroscopic adsorption models are formulated, based on fundamental principles of adsorption science and technology, that may be used for macroscopic (such as whole-building) contaminant dispersal analysis. The first family of adsorption models - the Equilibrium Adsorption (EA) Models - are based upon the simple requirement of equilibrium between adsorbent and room air. The second family - the Boundary Layer Diffusion Controlled Adsorption (BLDC) Models - add to the equilibrium requirement a boundary layer model for diffusion of the adsorbate from the room air to the adsorbent surface. Two members of each of these families are explicitly discussed, one based on the linear adsorption isotherm model and the other on the Langmuir model. The linear variants of each family are applied to model the adsorption dynamics of formaldehyde in gypsum wall board and compared to measured data.
Relating Macroscopic Thermal Phenomena with Molecular Models
NASA Astrophysics Data System (ADS)
Laws, Priscilla W.
2002-03-01
A series of observations and activities have been developed to help students enrich their understanding of how physicists can use model building to construct self-consistent models of physical reality.* This talk will describe the instructional use of integrated microcomputer-based laboratory measurements of macroscopic phenomena and digital video analysis of simulated microscopic events to help students understand the ideal gas law, the first law of thermodynamics, and heat engines. *Workshop Physics Activity Guide (Module 3), P. Laws, (John Wiley and Sons, Inc., NY, 1997).
Macroscopic balance model for wave rotors
NASA Technical Reports Server (NTRS)
Welch, Gerard E.
1996-01-01
A mathematical model for multi-port wave rotors is described. The wave processes that effect energy exchange within the rotor passage are modeled using one-dimensional gas dynamics. Macroscopic mass and energy balances relate volume-averaged thermodynamic properties in the rotor passage control volume to the mass, momentum, and energy fluxes at the ports. Loss models account for entropy production in boundary layers and in separating flows caused by blade-blockage, incidence, and gradual opening and closing of rotor passages. The mathematical model provides a basis for predicting design-point wave rotor performance, port timing, and machine size. Model predictions are evaluated through comparisons with CFD calculations and three-port wave rotor experimental data. A four-port wave rotor design example is provided to demonstrate model applicability. The modeling approach is amenable to wave rotor optimization studies and rapid assessment of the trade-offs associated with integrating wave rotors into gas turbine engine systems.
Macroscopic model for solvated ion dynamics
NASA Astrophysics Data System (ADS)
Chen, J.-H.; Adelman, S. A.
1980-02-01
A macroscopic treatment of solvated ion dynamics is developed and applied to calculate the limiting (zero concentration) conductance of cations in several aprotic solvents. The theory is based on a coupled set of electrostatic and hydrodynamic equations for the density, flow, and polarization fields induced in the polar solvent by a moving ion. These equations, which are derived by the Mori projection technique, include crucial local solvent structure (ion solvation) effects through solvent compressibility, and local constitutive parameters. If solvent structure is suppressed, the equations reduce to those derived previously by Onsager and Hubbard [J. B. Hubbard and L. Onsager, J. Chem. Phys. 67, 4850 (1977)]. The macroscopic equations are approximately decoupled into electrostatic and hydrodynamic parts. The decoupled equations are solved assuming a step density, viscosity, and dielectric constant model for the local solvent structure and dynamics. This yields analytic expressions for the viscous, ζV, and dielectric ζD, contributions to the ion friction coefficient. These expressions generalize, respectively, the Stokes and Zwanzig results for the (slip) viscous and dielectric friction so as to account for ion solvation effects. The friction coefficients involve a desolvation function Δ which depends on the local structure (density) and dynamics of the solvent. The drag coefficient results reduce in form to those of Zwanzig (within a flow gradient correction factor of 2/3) and Stokes for both weak (Δ→1) and strong (Δ→0) ion-solvent interaction. For Δ→1 the true ionic radius Ri appears in the drag formulas while for Δ→0 a renormalized solvated ion radius σ=Ri+2Rs (where Rs=solvent molecule radius) appears. The theory is fit to experimental cation conductances in pyridine, acetone, and acetonitrile by representing Δ by a two parameter switching function. Agreement between the model and experiment is satisfactory for all three solvents. Moreover
Macroscopic model of scanning force microscope
Guerra-Vela, Claudio; Zypman, Fredy R.
2004-10-05
A macroscopic version of the Scanning Force Microscope is described. It consists of a cantilever under the influence of external forces, which mimic the tip-sample interactions. The use of this piece of equipment is threefold. First, it serves as direct way to understand the parts and functions of the Scanning Force Microscope, and thus it is effectively used as an instructional tool. Second, due to its large size, it allows for simple measurements of applied forces and parameters that define the state of motion of the system. This information, in turn, serves to compare the interaction forces with the reconstructed ones, which cannot be done directly with the standard microscopic set up. Third, it provides a kinematics method to non-destructively measure elastic constants of materials, such as Young's and shear modules, with special application for brittle materials.
Microwave Diffraction Techniques from Macroscopic Crystal Models
ERIC Educational Resources Information Center
Murray, William Henry
1974-01-01
Discusses the construction of a diffractometer table and four microwave models which are built of styrofoam balls with implanted metallic reflecting spheres and designed to simulate the structures of carbon (graphite structure), sodium chloride, tin oxide, and palladium oxide. Included are samples of Bragg patterns and computer-analysis results.…
Microscopic to Macroscopic Dynamical Models of Sociality
NASA Astrophysics Data System (ADS)
Solis Salas, Citlali; Woolley, Thomas; Pearce, Eiluned; Dunbar, Robin; Maini, Philip; Social; Evolutionary Neuroscience Research Group (Senrg) Collaboration
To help them survive, social animals, such as humans, need to share knowledge and responsibilities with other members of the species. The larger their social network, the bigger the pool of knowledge available to them. Since time is a limited resource, a way of optimising its use is meeting amongst individuals whilst fulfilling other necessities. In this sense it is useful to know how many, and how often, early humans could meet during a given period of time whilst performing other necessary tasks, such as food gathering. Using a simplified model of these dynamics, which comprehend encounter and memory, we aim at producing a lower-bound to the number of meetings hunter-gatherers could have during a year. We compare the stochastic agent-based model to its mean-field approximation and explore some of the features necessary for the difference between low population dynamics and its continuum limit. We observe an emergent property that could have an inference in the layered structure seen in each person's social organisation. This could give some insight into hunter-gatherer's lives and the development of the social layered structure we have today. With support from the Mexican Council for Science and Technology (CONACyT), the Public Education Secretariat (SEP), and the Mexican National Autonomous University's Foundation (Fundacion UNAM).
Analysis and Enhancements of a Prolific Macroscopic Model of Epilepsy
Fietkiewicz, Christopher; Loparo, Kenneth A.
2016-01-01
Macroscopic models of epilepsy can deliver surprisingly realistic EEG simulations. In the present study, a prolific series of models is evaluated with regard to theoretical and computational concerns, and enhancements are developed. Specifically, we analyze three aspects of the models: (1) Using dynamical systems analysis, we demonstrate and explain the presence of direct current potentials in the simulated EEG that were previously undocumented. (2) We explain how the system was not ideally formulated for numerical integration of stochastic differential equations. A reformulated system is developed to support proper methodology. (3) We explain an unreported contradiction in the published model specification regarding the use of a mathematical reduction method. We then use the method to reduce the number of equations and further improve the computational efficiency. The intent of our critique is to enhance the evolution of macroscopic modeling of epilepsy and assist others who wish to explore this exciting class of models further. PMID:27144054
Macroscopic modeling for traffic flow on three-lane highways
NASA Astrophysics Data System (ADS)
Chen, Jianzhong; Fang, Yuan
2015-04-01
In this paper, a macroscopic traffic flow model for three-lane highways is proposed. The model is an extension of the speed gradient model by taking into account the lane changing. The new source and sink terms of lane change rate are added into the continuity equations and the speed dynamic equations to describe the lane-changing behavior. The result of the steady state analysis shows that our model can describe the lane usage inversion phenomenon. The numerical results demonstrate that the present model effectively reproduces several traffic phenomena observed in real traffic such as shock and rarefaction waves, stop-and-go waves and local clusters.
Fission barriers in a macroscopic-microscopic model
Dobrowolski, A.; Pomorski, K.; Bartel, J.
2007-02-15
In the framework of the macroscopic-microscopic model, this study investigates fission barriers in the region of actinide nuclei. A very effective four-dimensional shape parametrization for fissioning nuclei is proposed. Taking, in particular, the left-right mass asymmetric and nonaxial shapes into account is demonstrated to have a substantial effect on fission barrier heights. The influence of proton versus neutron deformation differences on the potential energy landscape of fissioning nuclei is also discussed.
Improved macroscopic traffic flow model for aggressive drivers
Mendez, A. R.; Velasco, R. M.
2011-03-24
As has been done for the treatment of diluted gases, kinetic methods are formulated for the study of unidirectional freeway traffic. Fluid dynamic models obtained from kinetic equations have inherent restrictions, the principal one is the restriction to the low density regime. Macroscopic models obtained from kinetic equations tends to selfrestrict to this regime and makes impossible to observe the medium density region. In this work, we present some results heading to improve this model and extend the observable region. Now, we are presenting a fluid dynamic model for aggressive drivers obtained from kinetic assumptions to extend the model to the medium density region in order to study synchronization phenomena which is a very interesting transition phase between free flow and traffic jams. We are changing the constant variance prefactor condition imposed before by a variance prefactor density dependent, the numerical solution of the model is presented, analyzed and contrasted with the previous one. We are also comparing our results with heuristic macroscopic models and real traffic observations.
Macroscopic traffic modeling with the finite difference method
Mughabghab, S.; Azarm, A.; Stock, D.
1996-03-15
A traffic congestion forecasting model (ATOP), developed in the present investigation, is described briefly. Several macroscopic models, based on the solution of the partial differential equation of conservation of vehicles by the finite difference method, were tested using actual traffic data. The functional form, as well as the parameters, of the equation of state which describes the relation between traffic speed and traffic density, were determined for a section of the Long Island Expressway. The Lax method and the forward difference technique were applied. The results of extensive tests showed that the Lax method, in addition to giving very good agreement with the traffic data, produces stable solutions.
Multiscale modelling of pharmaceutical powders: Macroscopic behaviour prediction
NASA Astrophysics Data System (ADS)
Loh, Jonathan; Ketterhagen, William; Elliott, James
2013-06-01
The pharmaceutical industry uses computer models at many stages during drug development. Quantum and molecular models are used to predict the crystal structures of potential active pharmaceutical ingredients (APIs), whereas discrete element models are used to optimise the mechanical properties of mixtures of APIs and excipient powders. The present work combines the strengths of modelling from all of the mentioned length scales to predict the behaviour of macroscopic powder granules from first principles using the molecular and crystal structures of acetazolamide as an example API. Starting with a single molecule of acetazolamide, ab initio self-consistent field calculations were used to calculate the equilibrium gas phase structure, vibrational spectra, interaction energy with water molecules and perform potential energy scans. By using these results and following the CHARMM General Force Field parameterisation process, all of the parameters required to perform a molecular dynamics simulation were iteratively determined using the CHARMM program. Next, by using crystallographic data from literature, the monoclinic and triclinic forms of the acetazolamide crystal were simulated. Material properties like the Young's modulus and Poisson ratio, and surface energies have been calculated. These material properties are then used as input parameters in a discrete element model containing Thornton's plastic model and the JKR cohesive force to predict the behaviour of macroscopic acetazolamide powder in angle of repose tests and tabletting simulations. Similar methodologies can be employed in the future to evaluate at an early stage the performance of novel APIs and excipients for tabletting applications.
A macroscopic analytical model of collaboration in distributed robotic systems.
Lerman, K; Galstyan, A; Martinoli, A; Ijspeert, A
2001-01-01
In this article, we present a macroscopic analytical model of collaboration in a group of reactive robots. The model consists of a series of coupled differential equations that describe the dynamics of group behavior. After presenting the general model, we analyze in detail a case study of collaboration, the stick-pulling experiment, studied experimentally and in simulation by Ijspeert et al. [Autonomous Robots, 11, 149-171]. The robots' task is to pull sticks out of their holes, and it can be successfully achieved only through the collaboration of two robots. There is no explicit communication or coordination between the robots. Unlike microscopic simulations (sensor-based or using a probabilistic numerical model), in which computational time scales with the robot group size, the macroscopic model is computationally efficient, because its solutions are independent of robot group size. Analysis reproduces several qualitative conclusions of Ijspeert et al.: namely, the different dynamical regimes for different values of the ratio of robots to sticks, the existence of optimal control parameters that maximize system performance as a function of group size, and the transition from superlinear to sublinear performance as the number of robots is increased.
A macroscopic model of traffic jams in axons.
Kuznetsov, A V; Avramenko, A A
2009-04-01
The purpose of this paper is to develop a minimal macroscopic model capable of explaining the formation of traffic jams in fast axonal transport. The model accounts for the decrease of the number density of positively (and negatively) oriented microtubules near the location of the traffic jam due to formation of microtubule swirls; the model also accounts for the reduction of the effective velocity of organelle transport in the traffic jam region due to organelles falling off microtubule tracks more often in the swirl region. The model is based on molecular-motor-assisted transport equations and the hydrodynamic model of traffic jams in highway traffic. Parametric analyses of the model's predictions for various values of viscosity of the traffic flow, variance of the velocity distribution, diffusivity of microtubule-bound and free organelles, rate constants for binding to and detachment from microtubules, relaxation time, and average motor velocities of the retrograde and anterograde transport, are carried out.
Towards a macroscopic modeling of the complexity in traffic flow.
Rosswog, Stephan; Wagner, Peter
2002-03-01
Based on the assumption of a safe velocity U(e)(rho) depending on the vehicle density rho, a macroscopic model for traffic flow is presented that extends the model of the Kühne-Kerner-Konhäuser by an interaction term containing the second derivative of U(e)(rho). We explore two qualitatively different forms of U(e): a conventional Fermi-type function and, motivated by recent experimental findings, a function that exhibits a plateau at intermediate densities, i.e., in this density regime the exact distance to the car ahead is only of minor importance. To solve the fluid-like equations a Lagrangian particle scheme is developed. The suggested model shows a much richer dynamical behavior than the usual fluid-like models. A large variety of encountered effects is known from traffic observations, many of which are usually assigned to the elusive state of "synchronized flow." Furthermore, the model displays alternating regimes of stability and instability at intermediate densities. It can explain data scatter in the fundamental diagram and complicated jam patterns. Within this model, a consistent interpretation of the emergence of very different traffic phenomena is offered: they are determined by the velocity relaxation time, i.e., the time needed to relax towards U(e)(rho). This relaxation time is a measure of the average acceleration capability and can be attributed to the composition (e.g., the percentage of trucks) of the traffic flow.
Macroscopic singlet oxygen model incorporating photobleaching as an input parameter
NASA Astrophysics Data System (ADS)
Kim, Michele M.; Finlay, Jarod C.; Zhu, Timothy C.
2015-03-01
A macroscopic singlet oxygen model for photodynamic therapy (PDT) has been used extensively to calculate the reacted singlet oxygen concentration for various photosensitizers. The four photophysical parameters (ξ, σ, β, δ) and threshold singlet oxygen dose ([1O2]r,sh) can be found for various drugs and drug-light intervals using a fitting algorithm. The input parameters for this model include the fluence, photosensitizer concentration, optical properties, and necrosis radius. An additional input variable of photobleaching was implemented in this study to optimize the results. Photobleaching was measured by using the pre-PDT and post-PDT sensitizer concentrations. Using the RIF model of murine fibrosarcoma, mice were treated with a linear source with fluence rates from 12 - 150 mW/cm and total fluences from 24 - 135 J/cm. The two main drugs investigated were benzoporphyrin derivative monoacid ring A (BPD) and 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH). Previously published photophysical parameters were fine-tuned and verified using photobleaching as the additional fitting parameter. Furthermore, photobleaching can be used as an indicator of the robustness of the model for the particular mouse experiment by comparing the experimental and model-calculated photobleaching ratio.
Macroscopic Computational Model of Dielectric Barrier Discharge Plasma Actuators
2006-02-01
Impulse Density Weighting ....................I-16 20. Boeuf and Pitchford Estimation of Wall- Jet Velocity...I-17 21. Boeuf and Pitchford Estimation of Wall- Jet Velocity (Close-up) ...........................I-17 22. Macroscopic View of X-momentum...II-4 28. Estimated Wall Jet Peak Velocity Magnitude (m/s) Compared to the Free Stream Velocity (m/s
Macroscopic model and truncation error of discrete Boltzmann method
NASA Astrophysics Data System (ADS)
Hwang, Yao-Hsin
2016-10-01
A derivation procedure to secure the macroscopically equivalent equation and its truncation error for discrete Boltzmann method is proffered in this paper. Essential presumptions of two time scales and a small parameter in the Chapman-Enskog expansion are disposed of in the present formulation. Equilibrium particle distribution function instead of its original non-equilibrium form is chosen as key variable in the derivation route. Taylor series expansion encompassing fundamental algebraic manipulations is adequate to realize the macroscopically differential counterpart. A self-contained and comprehensive practice for the linear one-dimensional convection-diffusion equation is illustrated in details. Numerical validations on the incurred truncation error in one- and two-dimensional cases with various distribution functions are conducted to verify present formulation. As shown in the computational results, excellent agreement between numerical result and theoretical prediction are found in the test problems. Straightforward extensions to more complicated systems including convection-diffusion-reaction, multi-relaxation times in collision operator as well as multi-dimensional Navier-Stokes equations are also exposed in the Appendix to point out its expediency in solving complicated flow problems.
Microscopic reversibility and macroscopic irreversibility: A lattice gas model
NASA Astrophysics Data System (ADS)
Pérez-Cárdenas, Fernando C.; Resca, Lorenzo; Pegg, Ian L.
2016-09-01
We present coarse-grained descriptions and computations of the time evolution of a lattice gas system of indistinguishable particles, whose microscopic laws of motion are exactly reversible, in order to investigate how or what kind of macroscopically irreversible behavior may eventually arise. With increasing coarse-graining and number of particles, relative fluctuations of entropy rapidly decrease and apparently irreversible behavior unfolds. Although that behavior becomes typical in those limits and within a certain range, it is never absolutely irreversible for any individual system with specific initial conditions. Irreversible behavior may arise in various ways. We illustrate one possibility by replacing detailed integer occupation numbers at lattice sites with particle probability densities that evolve diffusively.
Using travel times to simulate multi-dimensional bioreactive transport in time-periodic flows.
Sanz-Prat, Alicia; Lu, Chuanhe; Finkel, Michael; Cirpka, Olaf A
2016-04-01
In travel-time models, the spatially explicit description of reactive transport is replaced by associating reactive-species concentrations with the travel time or groundwater age at all locations. These models have been shown adequate for reactive transport in river-bank filtration under steady-state flow conditions. Dynamic hydrological conditions, however, can lead to fluctuations of infiltration velocities, putting the validity of travel-time models into question. In transient flow, the local travel-time distributions change with time. We show that a modified version of travel-time based reactive transport models is valid if only the magnitude of the velocity fluctuates, whereas its spatial orientation remains constant. We simulate nonlinear, one-dimensional, bioreactive transport involving oxygen, nitrate, dissolved organic carbon, aerobic and denitrifying bacteria, considering periodic fluctuations of velocity. These fluctuations make the bioreactive system pulsate: The aerobic zone decreases at times of low velocity and increases at those of high velocity. For the case of diurnal fluctuations, the biomass concentrations cannot follow the hydrological fluctuations and a transition zone containing both aerobic and obligatory denitrifying bacteria is established, whereas a clear separation of the two types of bacteria prevails in the case of seasonal velocity fluctuations. We map the 1-D results to a heterogeneous, two-dimensional domain by means of the mean groundwater age for steady-state flow in both domains. The mapped results are compared to simulation results of spatially explicit, two-dimensional, advective-dispersive-bioreactive transport subject to the same relative fluctuations of velocity as in the one-dimensional model. The agreement between the mapped 1-D and the explicit 2-D results is excellent. We conclude that travel-time models of nonlinear bioreactive transport are adequate in systems of time-periodic flow if the flow direction does not change.
Using travel times to simulate multi-dimensional bioreactive transport in time-periodic flows
NASA Astrophysics Data System (ADS)
Sanz-Prat, Alicia; Lu, Chuanhe; Finkel, Michael; Cirpka, Olaf A.
2016-04-01
In travel-time models, the spatially explicit description of reactive transport is replaced by associating reactive-species concentrations with the travel time or groundwater age at all locations. These models have been shown adequate for reactive transport in river-bank filtration under steady-state flow conditions. Dynamic hydrological conditions, however, can lead to fluctuations of infiltration velocities, putting the validity of travel-time models into question. In transient flow, the local travel-time distributions change with time. We show that a modified version of travel-time based reactive transport models is valid if only the magnitude of the velocity fluctuates, whereas its spatial orientation remains constant. We simulate nonlinear, one-dimensional, bioreactive transport involving oxygen, nitrate, dissolved organic carbon, aerobic and denitrifying bacteria, considering periodic fluctuations of velocity. These fluctuations make the bioreactive system pulsate: The aerobic zone decreases at times of low velocity and increases at those of high velocity. For the case of diurnal fluctuations, the biomass concentrations cannot follow the hydrological fluctuations and a transition zone containing both aerobic and obligatory denitrifying bacteria is established, whereas a clear separation of the two types of bacteria prevails in the case of seasonal velocity fluctuations. We map the 1-D results to a heterogeneous, two-dimensional domain by means of the mean groundwater age for steady-state flow in both domains. The mapped results are compared to simulation results of spatially explicit, two-dimensional, advective-dispersive-bioreactive transport subject to the same relative fluctuations of velocity as in the one-dimensional model. The agreement between the mapped 1-D and the explicit 2-D results is excellent. We conclude that travel-time models of nonlinear bioreactive transport are adequate in systems of time-periodic flow if the flow direction does not change.
The relation between a microscopic threshold-force model and macroscopic models of adhesion
NASA Astrophysics Data System (ADS)
Hulikal, Srivatsan; Bhattacharya, Kaushik; Lapusta, Nadia
2017-01-01
This paper continues our recent work on the relationship between discrete contact interactions at the microscopic scale and continuum contact interactions at the macroscopic scale (Hulikal et al., J. Mech. Phys. Solids 76, 144-161, 2015). The focus of this work is on adhesion. We show that a collection of a large number of discrete elements governed by a threshold-force based model at the microscopic scale collectively gives rise to continuum fracture mechanics at the macroscopic scale. A key step is the introduction of an efficient numerical method that enables the computation of a large number of discrete contacts. Finally, while this work focuses on scaling laws, the methodology introduced in this paper can also be used to study rough-surface adhesion.
NASA Astrophysics Data System (ADS)
Arie Cirpka, Olaf; Sanz-Prat, Alicia; Loschko, Matthias; Finkel, Michael; Lu, Chuanhe
2016-04-01
Travel-time based concepts of modeling subsurface transport have been established as computationally efficient alternatives to spatially explicit simulation methods. The spatial coordinates are replaced by travel time, resulting in one-dimensional transport with a constant „velocity" of unity. The concept is straight forward in linear transport applications, and under these conditions the results are exact provided that the coefficients of linear transport don't vary in space. In nonlinear transport, mixing can jeopardize the validity of the approach. This holds particularly true for transverse mixing, exchanging solute mass between streamtubes. We have performed systematic analyses of nonlinear bioreactive transport, involving oxygen, nitrate, organic carbon, as well as aerobic and denitrifying bacteria to analyzed under which conditions the errors introduced by travel-time and similar formulations are negligible. In steady-state flows with uniform reactive parameters, an excellent agreement between multi-dimensional reactive transport results, affected by transverse dispersion and flow heterogeneity, and one-dimensional travel-time results could be achieved by mapping the reactive-species concentrations to the multi-dimensional domain according to the local mean groundwater age. Aliasing of local transverse dispersion to macroscopically longitudinal mixing can be addressed by using a distance-dependent longitudinal dispersion coefficient. The approach also works for transient flows as long as the direction of flow remains constant and only the magnitude varies. Under these conditions, the groundwater age for the time-averaged velocity field is an adequate mapping variable, provided that flow transients are accounted for in the one- and multi-dimensional simulations. If the reaction takes place only in specific regions, the time of exposure to the according conditions is a better predictor of reactive transport than the overall travel time. Spatially variable
Zhao, Namula; Li, Xue-en; Wang, Mei; Hu, Da-lai
2009-08-01
Splintage external fixation in Chinese Mongolian osteopathy is a biological macroscopic model. In this model, the ideas of self-life "unity of mind and body" and vital natural "correspondence of nature and human" combine the physiological and psychological self-fixation with supplementary external fixation of fracture using small splints. This model implies macroscopic ideas of uncovering fixation and healing: structural stability integrating geometrical "dynamic" stability with mechanical "dynamic" equilibrium and the stability of state integrating statics with dynamics, and osteoblasts with osteoclasts, and psychological stability integrating closed and open systems of human and nature. These ideas indicate a trend of development in modern osteopathy.
Manufacturing of bioreactive nanofibers for bioremediation.
Tong, Ho-Wang; Mutlu, Baris R; Wackett, Lawrence P; Aksan, Alptekin
2014-08-01
Recombinant Escherichia coli (E. coli) cells were successfully encapsulated in reactive membranes comprised of electrospun nanofibers that have biocompatible polyvinyl alcohol (PVA)-based cores entrapping the E. coli and silica-based, mechanically sturdy porous shells. The reactive membranes were produced in a continuous fashion using a coaxial electrospinning system coupled to a microfluidic timer that mixed and regulated the reaction time of the silica precursor and the PVA solution streams. A factorial design method was employed to investigate the effects of the three critical design parameters of the system (the flow rate of the core solution, protrusion of the core needle, and the viscosity of the core solution) and to optimize these parameters for reproducibly and continuously producing high-quality core/shell nanofibers. The feasibility of using the reactive membranes manufactured in this fashion for bioremediation of atrazine, a herbicide, was also investigated. The atrazine degradation rate (0.24 µmol/g of E. coli/min) of the encapsulated E. coli cells expressing the atrazine-dechlorinating enzyme AtzA was measured to be relatively close to that measured with the free cells in solution (0.64 µmol/g of E. coli/min). We show here that the low cost, high flexibility, water insolubility, and high degradation efficiency of the bioreactive membranes manufactured with electrospinning makes it feasible for their wide-spread use in industrial scale bioremediation of contaminated waters.
A Macroscopic Model for a System of Swarming Agents Using Curvature Control
NASA Astrophysics Data System (ADS)
Degond, Pierre; Motsch, Sébastien
2011-05-01
In this paper, we study the macroscopic limit of a new model of collective displacement. The model, called PTWA, is a combination of the Vicsek alignment model (Vicsek et al. in Phys. Rev. Lett. 75(6):1226-1229, 1995) and the Persistent Turning Walker (PTW) model of motion by curvature control (Degond and Motsch in J. Stat. Phys. 131(6):989-1021, 2008; Gautrais et al. in J. Math. Biol. 58(3):429-445, 2009). The PTW model was designed to fit measured trajectories of individual fish (Gautrais et al. in J. Math. Biol. 58(3):429-445, 2009). The PTWA model (Persistent Turning Walker with Alignment) describes the displacements of agents which modify their curvature in order to align with their neighbors. The derivation of its macroscopic limit uses the non-classical notion of generalized collisional invariant introduced in (Degond and Motsch in Math. Models Methods Appl. Sci. 18(1):1193-1215, 2008). The macroscopic limit of the PTWA model involves two physical quantities, the density and the mean velocity of individuals. It is a system of hyperbolic type but is non-conservative due to a geometric constraint on the velocity. This system has the same form as the macroscopic limit of the Vicsek model (Degond and Motsch in Math. Models Methods Appl. Sci. 18(1):1193-1215, 2008) (the `Vicsek hydrodynamics') but for the expression of the model coefficients. The numerical computations show that the numerical values of the coefficients are very close. The `Vicsek Hydrodynamic model' appears in this way as a more generic macroscopic model of swarming behavior as originally anticipated.
Analog modeling of Worm-Like Chain molecules using macroscopic beads-on-a-string.
Tricard, Simon; Feinstein, Efraim; Shepherd, Robert F; Reches, Meital; Snyder, Phillip W; Bandarage, Dileni C; Prentiss, Mara; Whitesides, George M
2012-07-07
This paper describes an empirical model of polymer dynamics, based on the agitation of millimeter-sized polymeric beads. Although the interactions between the particles in the macroscopic model and those between the monomers of molecular-scale polymers are fundamentally different, both systems follow the Worm-Like Chain theory.
A macroscopic model for magnetic shape-memory single crystals
NASA Astrophysics Data System (ADS)
Bessoud, Anne-Laure; Kružík, Martin; Stefanelli, Ulisse
2013-04-01
A rate-independent model for the quasi-static magneto-elastic evolution of a magnetic shape-memory single crystal is presented. In particular, the purely mechanical Souza-Auricchio model for shape-memory alloys is here combined with classical micro-magnetism by suitably associating magnetization and inelastic strain. By balancing the effect of conservative and dissipative actions, a nonlinear evolution PDE system of rate-independent type is obtained. We prove the existence of so-called energetic solutions to this system. Moreover, we discuss several limits for the model corresponding to parameter asymptotics by means of a rigorous Γ-convergence argument.
Aristotelous, Andreas C; Haider, Mansoor A
2014-08-01
Macroscopic models accounting for cellular effects in natural or engineered tissues may involve unknown constitutive terms that are highly dependent on interactions at the scale of individual cells. Hybrid discrete models, which represent cells individually, were used to develop and apply techniques for modeling diffusive nutrient transport and cellular uptake to identify a nonlinear nutrient loss term in a macroscopic reaction-diffusion model of the system. Flexible and robust numerical methods were used, based on discontinuous Galerkin finite elements in space and a Crank-Nicolson temporal discretization. Scales were bridged via averaging operations over a complete set of subdomains yielding data for identification of a macroscopic nutrient loss term that was accurately captured via a fifth-order polynomial. Accuracy of the identified macroscopic model was demonstrated by direct, quantitative comparisons of the tissue and cellular scale models in terms of three error norms computed on a mesoscale mesh.
The future of stellar model atmospheres: macroscopic nightmares?
NASA Astrophysics Data System (ADS)
Asplund, M.
Stellar atmospheres represent unique windows for understanding stellar, galactic and cosmic evolution by being responsible for the emission of stellar spectra. Much progress has been made over the years in modelling stellar atmospheres but still the modelling efforts are hampered by various, often questionable, assumptions and approximations. This review describes promising avenues for improving the realism of stellar model atmospheres for hot (spectral types O, B, A), cool (F, G, K) and very cool (M and later) stars, respectively, in the coming decade. A common theme will be time-dependent 3D hydrodynamical calculations with a detailed non-LTE treatment of the radiative transfer. It is argued that this is fully within the realm of possibility on this time-scale and indeed will be necessary to complement the expected advances on the observational side.
From microscopic taxation and redistribution models to macroscopic income distributions
NASA Astrophysics Data System (ADS)
Bertotti, Maria Letizia; Modanese, Giovanni
2011-10-01
We present here a general framework, expressed by a system of nonlinear differential equations, suitable for the modeling of taxation and redistribution in a closed society. This framework allows one to describe the evolution of income distribution over the population and to explain the emergence of collective features based on knowledge of the individual interactions. By making different choices of the framework parameters, we construct different models, whose long-time behavior is then investigated. Asymptotic stationary distributions are found, which enjoy similar properties as those observed in empirical distributions. In particular, they exhibit power law tails of Pareto type and their Lorenz curves and Gini indices are consistent with some real world ones.
General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures
NASA Astrophysics Data System (ADS)
Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel
2015-04-01
This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy
General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures.
Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel
2015-04-07
This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy
Macroscopic modeling for heat and water vapor transfer in dry snow by homogenization.
Calonne, Neige; Geindreau, Christian; Flin, Frédéric
2014-11-26
Dry snow metamorphism, involved in several topics related to cryospheric sciences, is mainly linked to heat and water vapor transfers through snow including sublimation and deposition at the ice-pore interface. In this paper, the macroscopic equivalent modeling of heat and water vapor transfers through a snow layer was derived from the physics at the pore scale using the homogenization of multiple scale expansions. The microscopic phenomena under consideration are heat conduction, vapor diffusion, sublimation, and deposition. The obtained macroscopic equivalent model is described by two coupled transient diffusion equations including a source term arising from phase change at the pore scale. By dimensional analysis, it was shown that the influence of such source terms on the overall transfers can generally not be neglected, except typically under small temperature gradients. The precision and the robustness of the proposed macroscopic modeling were illustrated through 2D numerical simulations. Finally, the effective vapor diffusion tensor arising in the macroscopic modeling was computed on 3D images of snow. The self-consistent formula offers a good estimate of the effective diffusion coefficient with respect to the snow density, within an average relative error of 10%. Our results confirm recent work that the effective vapor diffusion is not enhanced in snow.
General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures
Liu, Yen Vinokur, Marcel; Panesi, Marco; Sahai, Amal
2015-04-07
This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model’s accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy
Macroscopic Modeling of the singlet oxygen production during PDT
Zhu, Timothy C; Finlay, Jarod C.; Zhou, Xiaodong; Li, Jun
2015-01-01
Photodynamic therapy (PDT) dose, D, is defined as the absorbed dose by the photosensitizer during photodynamic therapy. It is proportional to the product of photosensitizer concentration and the light fluence. This quantity can be directly characterized during PDT and is considered to be predictive of photodynamic efficacy under ample oxygen supply. For type-II photodynamic interaction, the cell killing is caused by the reaction of cellular acceptors with singlet oxygen. The production of singlet oxygen can be expressed as ηD, where η is the singlet oxygen quantum yield and is a constant under ample oxygen supply. For most PDT, it is desirable to also take into account the effect of tissue oxygenation. We have modeled the coupled kinetics equation of the concentrations of the singlet oxygen, the photosensitizers in ground and triplet states, the oxygen, and tissue acceptors along with the diffusion equation governing the light transport in turbid medium. We have shown that it is possible to express η as a function of local oxygen concentration during PDT and this expression is a good approximation to predict the production of singlet oxygen during PDT. Theoretical estimation of the correlation between the tissue oxygen concentration and hemoglobin concentration, oxygen saturation, and blood flow is presented. PMID:25983366
NASA Astrophysics Data System (ADS)
Solano, Javier; Duarte, José; Vargas, Erwin; Cabrera, Jhon; Jácome, Andrés; Botero, Mónica; Rey, Juan
2016-10-01
This paper addresses the Energetic Macroscopic Representation EMR, the modelling and the control of photovoltaic panel PVP generation systems for simulation purposes. The model of the PVP considers the variations on irradiance and temperature. A maximum power point tracking MPPT algorithm is considered to control the power converter. A novel EMR is proposed to consider the dynamic model of the PVP with variations in the irradiance and the temperature. The EMR is evaluated through simulations of a PVP generation system.
Microscopic Simulation and Macroscopic Modeling for Thermal and Chemical Non-Equilibrium
NASA Technical Reports Server (NTRS)
Liu, Yen; Panesi, Marco; Vinokur, Marcel; Clarke, Peter
2013-01-01
This paper deals with the accurate microscopic simulation and macroscopic modeling of extreme non-equilibrium phenomena, such as encountered during hypersonic entry into a planetary atmosphere. The state-to-state microscopic equations involving internal excitation, de-excitation, dissociation, and recombination of nitrogen molecules due to collisions with nitrogen atoms are solved time-accurately. Strategies to increase the numerical efficiency are discussed. The problem is then modeled using a few macroscopic variables. The model is based on reconstructions of the state distribution function using the maximum entropy principle. The internal energy space is subdivided into multiple groups in order to better describe the non-equilibrium gases. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients. The modeling is completely physics-based, and its accuracy depends only on the assumed expression of the state distribution function and the number of groups used. The model makes no assumption at the microscopic level, and all possible collisional and radiative processes are allowed. The model is applicable to both atoms and molecules and their ions. Several limiting cases are presented to show that the model recovers the classical twotemperature models if all states are in one group and the model reduces to the microscopic equations if each group contains only one state. Numerical examples and model validations are carried out for both the uniform and linear distributions. Results show that the original over nine thousand microscopic equations can be reduced to 2 macroscopic equations using 1 to 5 groups with excellent agreement. The computer time is decreased from 18 hours to less than 1 second.
NASA Astrophysics Data System (ADS)
Lanzafame, Giuseppe
2015-02-01
In the nonlinear Navier-Stokes viscous flow dynamics, physical damping is mathematically accomplished by a braking term in the momentum equation, corresponding to a heating term in the energy equation, both responsible of the conversion of mechanical energy into heat. In such two terms, it is essential the role of the viscous stress tensor, relative to contiguous macroscopic moving flow components, depending on the macroscopic viscosity coefficient ν. A working formulation for ν can always be found analytically, tuning some arbitrary parameters in the current known formulations, according to the geometry, morphology and physics of the flow. Instead, in this paper, we write an alternative hybrid formulation for ν, where molecular parameters are also included. Our expression for ν has a more physical interpretation of the internal damping in dilute gases because the macroscopic viscosity is related to the small scale molecular dissipation, not strictly dependent on the flow morphology, as well as it is free of any arbitrary parameter. Results for some basic 2D tests are shown in the smoothed particle hydrodynamics (SPH) framework. An application to the 3D accretion disc modeling for low mass cataclysmic variables is also discussed. Consequences of the macroscopic viscosity coefficient reformulation in a more strictly physical terms on the thermal conductivity coefficient for dilute gases are also discussed.
Determination of the low concentration correction in the macroscopic singlet oxygen model for PDT
NASA Astrophysics Data System (ADS)
Kim, Michele M.; Penjweini, Rozhin; Finlay, Jarod C.; Zhu, Timothy C.
2016-03-01
The macroscopic singlet oxygen model has been used for singlet oxygen explicit dosimetry in photodynamic therapy (PDT). The photophysical parameters for commonly used sensitizers, HPPH and BPD, have been investigated in pre-clinical studies using mouse models. So far, studies have involved optimizing fitting algorithms to obtain the some of the photophysical parameters (ξ, σ, g) and the threshold singlet oxygen dose ([1O2]rx,sh), while other parameters such as the low concentration correction, δ, has been kept as a constant. In this study, using photobleaching measurements of mice in vivo, the value of δ was also optimized and fit to better describe experimental data. Furthermore, the value of the specific photobleaching ratio (σ) was also fine-tuned using the photobleaching results. Based on literature values of δ, σ for photosensitizers can be uniquely determined using the additional photobleaching measurements. This routine will further improve the macroscopic model of singlet oxygen production for use in explicit dosimetry.
Sugimachi, Masaru; Sunagawa, Kenji; Uemura, Kazunori; Kamiya, Atsunori; Shimizu, Shuji; Inagaki, Masashi; Shishido, Toshiaki
2009-01-01
Comprehensive understanding of hemodynamics remains a challenge even for expert cardiologists, partially due to a lack of an appropriate macroscopic model. We attempted to amend three major problems of Guyton's conceptual model (unknown left atrial pressure, unilateral heart damage, blood redistribution) and developed a comprehensive macroscopic model of hemodynamics that provides quantitative information. We incorporated a third axis of left atrial pressure, resulting in a 3D coordinate system. Pump functions of left and right heart are expressed by an integrated cardiac output curve, and the capacitive function of total vasculature by a venous return surface. The equations for both the cardiac output curve and venous return surface would facilitate precise diagnosis (especially evaluation of blood volume) and choice of appropriate treatments, including application to autopilot systems.
Fission properties of Po isotopes in different macroscopic-microscopic models
NASA Astrophysics Data System (ADS)
Bartel, J.; Pomorski, K.; Nerlo-Pomorska, B.; Schmitt, Ch
2015-11-01
Fission-barrier heights of nuclei in the Po isotopic chain are investigated in several macroscopic-microscopic models. Using the Yukawa-folded single-particle potential, the Lublin-Strasbourg drop (LSD) model, the Strutinsky shell-correction method to yield the shell corrections and the BCS theory for the pairing contributions, fission-barrier heights are calculated and found in quite good agreement with the experimental data. This turns out, however, to be only the case when the underlying macroscopic, liquid-drop (LD) type, theory is well chosen. Together with the LSD approach, different LD parametrizations proposed by Moretto et al are tested. Four deformation parameters describing respectively elongation, neck-formation, reflectional-asymmetric, and non-axiality of the nuclear shape thus defining the so called modified Funny Hills shape parametrization are used in the calculation. The present study clearly demonstrates that nuclear fission-barrier heights constitute a challenging and selective tool to discern between such different macroscopic approaches.
Multivariate crash modeling for motor vehicle and non-motorized modes at the macroscopic level.
Lee, Jaeyoung; Abdel-Aty, Mohamed; Jiang, Ximiao
2015-05-01
Macroscopic traffic crash analyses have been conducted to incorporate traffic safety into long-term transportation planning. This study aims at developing a multivariate Poisson lognormal conditional autoregressive model at the macroscopic level for crashes by different transportation modes such as motor vehicle, bicycle, and pedestrian crashes. Many previous studies have shown the presence of common unobserved factors across different crash types. Thus, it was expected that adopting multivariate model structure would show a better modeling performance since it can capture shared unobserved features across various types. The multivariate model and univariate model were estimated based on traffic analysis zones (TAZs) and compared. It was found that the multivariate model significantly outperforms the univariate model. It is expected that the findings from this study can contribute to more reliable traffic crash modeling, especially when focusing on different modes. Also, variables that are found significant for each mode can be used to guide traffic safety policy decision makers to allocate resources more efficiently for the zones with higher risk of a particular transportation mode.
Biochemical Mechanisms controlling Bioreactivity of Adrenal Chromaffin Cells
1988-06-17
conditioning in the laboratory rat . B. Examination of the morphological changes that accompany changes in bioreactivity of the rat adrenal medulla: When... Laboratory Rat . Proc. Western Pharmacol. Soc. 29: 315-318, 1986. Campbell, D. C., Hardie, D. G. and Vulliet, P. R. Identification of four Phosphorylation...Robert Lennox (New York, Plenum Press, 1987) pp 367-374. Vulliet, P. R., Loskutoff, N. and Kraemer, D. A Technique of Embryo Transfer in the
NASA Technical Reports Server (NTRS)
Duffy, Stephen F.; Manderscheid, Jane M.
1989-01-01
A macroscopic noninteractive reliability model for ceramic matrix composites is presented. The model is multiaxial and applicable to composites that can be characterized as orthotropic. Tensorial invariant theory is used to create an integrity basis with invariants that correspond to physical mechanisms related to fracture. This integrity basis is then used to construct a failure function per unit volume (or area) of material. It is assumed that the overall strength of the composite is governed by weakest link theory. This leads to a Weibull type model similar in nature to the principle of independent action (PIA) model for isotropic monolithic ceramics. An experimental program to obtain model parameters is briefly discussed. In addition, qualitative features of the model are illustrated by presenting reliability surfaces for various model parameters.
Macroscopic thermoplastic model applied to the high pressure torsion of metallic glasses
Hobor, Sandor; Revesz, Adam; Kovacs, Zsolt
2009-07-15
Shear deformation generated temperature rise in metallic glasses is estimated in a macroscopic three-dimensional axial symmetric thermoplastic model. Numerical solution of heat-conduction equation provides the time evolution and spatial distribution of temperature for high pressure torsion in the present paper. We have shown that small sample thickness and/or high deformation rate enables the temperature to exceed the glass transition in the entire sample, yielding a transition of the deformation mode from inhomogeneous to homogeneous viscous flow. However, in other cases only a small temperature increase is predicted in line with literature data.
Stelzer, Michael; Sun, Jibin; Kamphans, Tom; Fekete, Sándor P; Zeng, An-Ping
2011-11-01
The bioreaction database established by Ma and Zeng (Bioinformatics, 2003, 19, 270-277) for in silico reconstruction of genome-scale metabolic networks has been widely used. Based on more recent information in the reference databases KEGG LIGAND and Brenda, we upgrade the bioreaction database in this work by almost doubling the number of reactions from 3565 to 6851. Over 70% of the reactions have been manually updated/revised in terms of reversibility, reactant pairs, currency metabolites and error correction. For the first time, 41 spontaneous sugar mutarotation reactions are introduced into the biochemical database. The upgrade significantly improves the reconstruction of genome scale metabolic networks. Many gaps or missing biochemical links can be recovered, as exemplified with three model organisms Homo sapiens, Aspergillus niger, and Escherichia coli. The topological parameters of the constructed networks were also largely affected, however, the overall network structure remains scale-free. Furthermore, we consider the problem of computing biologically feasible shortest paths in reconstructed metabolic networks. We show that these paths are hard to compute and present solutions to find such paths in networks of small and medium size.
NASA Technical Reports Server (NTRS)
Gatsonis, Nikos A.; Alexandrou, Andreas; Shi, Hui; Ongewe, Bernard; Sacco, Albert, Jr.
1999-01-01
. At the same time, however, there is increased urgency to develop such an understanding in order to more accurately quantify the process. In order to better understand the results obtained from our prior space experiments, and design future experiments, a detailed fluid dynamic model simulating the crystal growth mechanism is required. This will not only add to the fundamental knowledge on the crystallization of zeolites, but also be useful in predicting the limits of size and growth of these important industrial materials. Our objective is to develop macro/microscopic theoretical and computational models to study the effect of transport phenomena in the growth of crystals grown in solutions. Our effort has concentrated so far in the development of separate macroscopic and microscopic models. The major highlights of our accomplishments are described.
Numerical study of a macroscopic finite pulse model of the diffusion MRI signal.
Li, Jing-Rebecca; Nguyen, Hang Tuan; Nguyen, Dang Van; Haddar, Houssem; Coatléven, Julien; Le Bihan, Denis
2014-11-01
Diffusion magnetic resonance imaging (dMRI) is an imaging modality that probes the diffusion characteristics of a sample via the application of magnetic field gradient pulses. The dMRI signal from a heterogeneous sample includes the contribution of the water proton magnetization from all spatial positions in a voxel. If the voxel can be spatially divided into different Gaussian diffusion compartments with inter-compartment exchange governed by linear kinetics, then the dMRI signal can be approximated using the macroscopic Karger model, which is a system of coupled ordinary differential equations (ODEs), under the assumption that the duration of the diffusion-encoding gradient pulses is short compared to the diffusion time (the narrow pulse assumption). Recently, a new macroscopic model of the dMRI signal, without the narrow pulse restriction, was derived from the Bloch-Torrey partial differential equation (PDE) using periodic homogenization techniques. When restricted to narrow pulses, this new homogenized model has the same form as the Karger model. We conduct a numerical study of the new homogenized model for voxels that are made up of periodic copies of a representative volume that contains spherical and cylindrical cells of various sizes and orientations and show that the signal predicted by the new model approaches the reference signal obtained by solving the full Bloch-Torrey PDE in O(ε(2)), where ε is the ratio between the size of the representative volume and a measure of the diffusion length. When the narrow gradient pulse assumption is not satisfied, the new homogenized model offers a much better approximation of the full PDE signal than the Karger model. Finally, preliminary results of applying the new model to a voxel that is not made up of periodic copies of a representative volume are shown and discussed.
Macroscopic Phase-Field Model of Partial Wetting: Bubbles in a Capillary Tube
NASA Astrophysics Data System (ADS)
Cueto-Felgueroso, Luis; Juanes, Ruben
2012-04-01
Drops and bubbles are nonspreading, local, compactly supported features. They are also equilibrium configurations in partial wetting phenomena. Yet, current macroscopic theories of capillary-dominated flow are unable to describe these systems. We propose a framework to model multiphase flow in porous media with nonspreading equilibrium configurations. We illustrate our approach with a one-dimensional model of two-phase flow in a capillary tube. Our model allows for the presence of compactons: nonspreading steady-state solutions in the absence of external forces. We show that local rate dependency is not needed to explain globally rate-dependent displacement patterns, and we interpret dynamic wetting transitions as the route from equilibrium, capillary-dominated configurations, towards viscous-dominated flow. Mathematically, these transitions are possible due to nonclassical shock solutions and the role of bistability and higher-order terms in our model.
Comparison of macroscopic models of excitation and force propagation in the heart.
Sachse, F B; Blümcke, L G; Mohr, M; Glänzel, K; Häfner, J; Riedel, C; Seemann, G; Skipa, O; Werner, C D; Dössel, O
2002-01-01
Computer aided simulations of the heart provide knowledge of phenomena, which are commonly neither visible nor measurable with current techniques. This knowledge can be applied e.g. in cardiologic diagnosis and therapy. A variety of models was created to reconstruct cardiac processes, e.g. electrical propagation and force development. In this work different macroscopic models were compared, i.e. models based on excitation-diffusion equations and cellular automata. The comparison was carried out concerning reconstruct-ability of cardiac phenomena, mathematical and biophysical foundation as well as computational expense. Particularly, the reconstruct-ability of electromechanic feedback mechanisms was examined. Perspectives for further developments and improvements of models were given.
Richelle, A; Ben Tahar, I; Hassouna, M; Bogaerts, Ph
2015-09-01
Inorganic nitrogen supplementation is commonly used to boost fermentation metabolism in yeast cultures. However, an excessive addition can induce an opposite effect. Hence, it is important to ensure that the ammonia supplemented to the culture leads to an improvement of the ethanol production while avoiding undesirable inhibition effects. To this end, a macroscopic model describing the influence of ammonia addition on Saccharomyces cerevisiae metabolism during bioethanol production from potato peel wastes has been developed. The model parameters are obtained by a simplified identification methodology in five steps. It is validated with experimental data and successfully predicts the dynamics of growth, substrate consumption (ammonia and fermentable sugar sources) and bioethanol production, even in cross validation. The model is used to determine the optimal quantity of supplemented ammonia required for maximizing bioethanol production from potato peel wastes in batch cultures.
Global properties of even-even superheavy nuclei in macroscopic-microscopic models
Baran, Andrzej; Lojewski, Zdzislaw; Sieja, Kamila; Kowal, Michal
2005-10-01
A systematic study of global properties of superheavy nuclei in the framework of macroscopic-microscopic method is performed. Equilibrium deformations, masses, quadrupole moments, radii, shell energies, fission barriers and half-lives are calculated using the following macroscopic models: Myers-Swiatecki liquid drop, droplet, Yukawa-plus-exponential, and Lublin-Strasbourg drop. Shell and pairing energies are calculated in Woods-Saxon potential with a universal set of parameters. The analysis covers a wide range of even-even superheavy nuclei from Z=100 to 122. Magic and semimagic numbers occurring in this region are indicated and their influence on the observables is discussed. The strongest shell effects appear at proton number Z=114 and at neutron number N=184. Deformed shell closures are found at N=152 and 162. Spontaneous fission half-lives are calculated in a dynamical approach where the full minimization of the action integral in a three-dimensional deformation space of {beta} deformations is performed. The fission half-lives obtained this way are two orders of magnitude smaller than the ones resulting from static calculations. The agreement of theoretical results and experimental data is satisfying.
Macroscopic surface tension in a lattice Bhatnagar-Gross-Krook model of two immiscible fluids
NASA Astrophysics Data System (ADS)
Halliday, I.; Thompson, S. P.; Care, C. M.
1998-01-01
We present a method by which an interface generating algorithm, similar to that of earlier lattice Boltzmann models of immiscible fluids, may be extended to a two component, two-speed two-dimensional (D2), nine-link (Q9) lattice Bhatnagar-Gross-Krook fluid. For two-dimensional, microcurrent-free planar interfaces between the two immiscible fluids we derive expressions for static interfacial tensions and interfacial distributions of the two fluids. Extending our analysis to curved interfaces, we propose a scheme for incorporating the influence of interfacial microcurrents that is based upon general symmetry arguments and is correct to second order in lattice velocity. The analysis demonstrates that the interfacial microcurrents have only second-order influence upon the macroscopic behavior of the model. We find good agreement between our calculations and simulation results based on the microcurrent stream function and surface tension results from the pressure tensor or Laplace law.
Macroscopic Surface Tension in a Lattice Boltzmann BGK Model of Two Immiscible Fluids.
NASA Astrophysics Data System (ADS)
Thompson, S. P.; Halliday, I.; Care, C. M.
1997-08-01
We present a method by which an interface generating algorithm, similar to that of earlier lattice Boltzmann models of immisible fluids, may be extended to a two component, two-speed D2Q9 lattice Bhatnagar Gross Krook fluid. For two-dimensional, microcurrent-free planar interfaces between the two immiscible fluids we derive expressions for static interfacial tensions and interfacial distributions of the two fluids. Extending our analysis to curved interfaces we propose a scheme for incorporating the influence of interfacial microcurrents which is based upon general symmetry arguments and is correct to second order in lattice velocity. The analysis demonstrates that the interfacial microcurrents have only second order influence upon the macroscopic behaviour of the model. We find good agreement between our calculations and simulation results based on the microcurrent stream function and surface tension results from the pressure tensor or Laplace law.
Hernández Velázquez, J D; Barroso-Flores, J; Gama Goicochea, A
2016-11-23
Two of the most commonly encountered friction-reducing agents used in plastic sheet production are the amides known as erucamide and behenamide, which despite being almost identical chemically, lead to markedly different values of the friction coefficient. To understand the origin of this contrasting behavior, in this work we model brushes made of these two types of linear-chain molecules using quantum mechanical numerical simulations under the density functional theory at the B97D/6-31G(d,p) level of theory. Four chains of erucamide and behenamide were linked to a 2 × 10 zigzag graphene sheet and optimized both in vacuum and in continuous solvent using the SMD implicit solvation model. We find that erucamide chains tend to remain closer together through π-π stacking interactions arising from the double bonds located at C13-C14, a feature behenamide lacks, and thus a more spread configuration is obtained with the latter. It is argued that this arrangement of the erucamide chains is responsible for the lower friction coefficient of erucamide brushes, compared with behenamide brushes, which is a macroscopic consequence of cooperative quantum mechanical interactions. While only quantum level interactions are modeled here, we show that behenamide chains are more spread out in the brush than erucamide chains as a consequence of those interactions. The spread-out configuration allows more solvent particles to penetrate the brush, leading in turn to more friction, in agreement with macroscopic measurements and mesoscale simulations of the friction coefficient reported in the literature.
The macroscopic behavior of cumulus ensembles simulated by a cumulus ensemble model
Kuan-Man Xu; Akio Arakawa; Krueger, S.K. )
1992-12-15
The two-dimensional UCLA cumulus ensemble model (CEM), which covers a large horizontal area with a sufficiently small horizontal grid size, is used in this study. A number of simulation experiments are performed with the CEM to study the macroscopic behavior of cumulus convection under a variety of different large-scale and underlying surface conditions. Specifically, the modulation of cumulus activity by the imposed large-scale processes and the eddy kinetic energy (EKE) budget are investigated in detail. In all simulations, cumulus convection is rather strongly modulated by large-scale advective processes in spite of the existence of some nonmodulated high-frequency fluctuations. The modulation exhibits some phase delays, however, when the basic wind shear is strong. This is presumably associated with the existence of mesoscale convective organization. The EKE budget analysis shows that the net eddy buoyancy generation rate is nearly zero for a wide range of cumulus ensembles. 34 refs., 17 figs., 2 tabs.
Micromechanical and macroscopic models of ductile fracture in particle reinforced metallic materials
NASA Astrophysics Data System (ADS)
Hu, Chao; Bai, Jie; Ghosh, Somnath
2007-06-01
This paper is aimed at developing two modules contributing to the overall framework of multi-scale modelling of ductile fracture of particle reinforced metallic materials. The first module is for detailed micromechanical analysis of particle fragmentation and matrix cracking of heterogeneous microstructures. The Voronoi cell FEM for particle fragmentation is extended in this paper to incorporate ductile failure through matrix cracking in the form of void growth and coalescence using a non-local Gurson-Tvergaard-Needleman (GTN) model. In the resulting enriched Voronoi cell finite element model (VCFEM) or E-VCFEM, the assumed stress-based hybrid VCFEM formulation is overlaid with narrow bands of displacement based elements to accommodate strain softening in the constitutive behaviour. The second module develops an anisotropic plasticity-damage model in the form of the GTN model for macroscopic analysis in the multi-scale material model. Parameters in this model are calibrated from results of homogenization of microstructural variables obtained by E-VCFEM analysis of microstructural representative volume element. Numerical examples conducted yield satisfactory results.
Numerical model for macroscopic quantum superpositions based on phase-covariant quantum cloning
NASA Astrophysics Data System (ADS)
Buraczewski, A.; Stobińska, M.
2012-10-01
Macroscopically populated quantum superpositions pose a question to what extent the macroscopic world obeys quantum mechanical laws. Recently, such superpositions for light, generated by an optimal quantum cloner, have been demonstrated. They are of fundamental and technological interest. We present numerical methods useful for modeling of these states. Their properties are governed by a Gaussian hypergeometric function, which cannot be reduced to either elementary or easily tractable functions. We discuss the method of efficient computation of this function for half-integer parameters and a moderate value of its argument. We show how to dynamically estimate a cutoff for infinite sums involving this function performed over its parameters. Our algorithm exceeds double precision and is parallelizable. Depending on the experimental parameters it chooses one of the several ways of summation to achieve the best efficiency. The methods presented here can be adjusted for analysis of similar experimental schemes. Program summary Program title: MQSVIS Catalogue identifier: AEMR_ v1_ 0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMR_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 1643 No. of bytes in distributed program, including test data, etc.: 13212 Distribution format: tar.gz Programming language: C with OpenMP extensions (main numerical program), Python (helper scripts). Computer: Modern PC (tested on AMD and Intel processors), HP BL2x220. Operating system: Unix/Linux. Has the code been vectorized or parallelized?: Yes (OpenMP). RAM: 200 MB for single run for 1000×1000 tile Classification: 4.15, 18. External routines: OpenMP Nature of problem: Recently, macroscopically populated quantum superpositions for light, generated by an optimal quantum cloner, have
Improving macroscopic modeling of the effect of water and osmotic stresses on root water uptake.
NASA Astrophysics Data System (ADS)
Jorda Guerra, Helena; Vanderborght, Jan
2015-04-01
Accurate modeling of water and salt stresses on root water uptake is critical for predicting impacts of global change and climate variability on crop production and soil water balances. Soil-hydrological models use reduction functions to represent the effect of osmotic stress in transpiration. However, these functions, which were developed empirically, present limitations in relation to the time and spatial scale at which they need to be used, fail to include compensation processes and do not agree on how water and salt stresses interact. This research intends to develop a macroscopic reduction function for water and osmotic stresses based on biophysical knowledge. Simulation experiments are conducted for a range of atmospheric conditions, soil and plant properties, irrigation water quality and scheduling using a 3-D physically-based model that resolves flow and transport to individual root segments and that couples flow in the soil and root system (Schröder et al., 2013). The effect of salt concentrations on water flow in the soil-root system is accounted for by including osmotic water potential gradients between the solution at the soil root interface and the root xylem sap in the hydraulic gradient between the soil and root. In a first step, simulation experiments are carried out in a soil volume around a single root segment. We discuss how the simulation setup can be defined so as to represent: (i) certain characteristics of the root system such as rooting depth and root length density, (ii) plant transpiration rate, (iii) leaching fraction of the irrigation, and (iii) salinity of the irrigation water. The output of these simulation experiments gives a first insight in the effect of salinity on transpiration and on the relation between the bulk salinity in the soil voxel, which is used in macroscopic salt stress functions of models that do not resolve processes at the root segment scale, and the salinity at the soil-root interface, which determines the actual
A master equation formalism for macroscopic modeling of asynchronous irregular activity states.
El Boustani, Sami; Destexhe, Alain
2009-01-01
Many efforts have been devoted to modeling asynchronous irregular (AI) activity states, which resemble the complex activity states seen in the cerebral cortex of awake animals. Most of models have considered balanced networks of excitatory and inhibitory spiking neurons in which AI states are sustained through recurrent sparse connectivity, with or without external input. In this letter we propose a mesoscopic description of such AI states. Using master equation formalism, we derive a second-order mean-field set of ordinary differential equations describing the temporal evolution of randomly connected balanced networks. This formalism takes into account finite size effects and is applicable to any neuron model as long as its transfer function can be characterized. We compare the predictions of this approach with numerical simulations for different network configurations and parameter spaces. Considering the randomly connected network as a unit, this approach could be used to build large-scale networks of such connected units, with an aim to model activity states constrained by macroscopic measurements, such as voltage-sensitive dye imaging.
NASA Astrophysics Data System (ADS)
Pavlyk, Vitaliy; Dilthey, Ulrich
2004-01-01
The microstructure exerts a strong influence on the mechanical properties and on the integrity of welded joints. Prediction of the formation of the microstructure during welding and of other solidification processes may be an important and supporting factor for technology optimization. Nowadays, increasing computing power allows direct simulations of the dendritic and cell morphology of columnar grains in the molten zone for specific temperature conditions. Modelling is carried out, on the one hand, with the finite difference—cellular automata and, on the other hand, with the phase field method. Determination of the solidification conditions during fusion welding (temperature gradient, local solidification rate, weld pool shape) is carried out with a numerical macroscopic finite element modelling calculation of the weld pool fluid flow and of the temperature distribution, as presented in this paper. As with the use of accurate physical models, the simulations are carried out with a spatial resolution of the microstructure, and many assumptions and restrictions from traditional, analytical or phenomenological models may be eliminated. The possibilities of using numerical algorithms for generation and visualization of microstructure formation during solidification are demonstrated. The spectrum of applications extends from welding and casting to processes with rapid solidification. In particular, computer simulations of the solidification conditions and the formation of a dendritic morphology during the directional solidification in gas-tungsten-arc welding are described. Moreover, the simulation results are compared with the experimental findings.
Wu, M; Li, J; Ludwig, A; Kharicha, A
2014-09-01
Part 1 of this two-part investigation presented a multiphase solidification model incorporating the finite diffusion kinetics and ternary phase diagram with the macroscopic transport phenomena (Wu et al., 2013). In Part 2, the importance of proper treatment of the finite diffusion kinetics in the calculation of macrosegregation is addressed. Calculations for a two-dimensional (2D) square casting (50 × 50 mm(2)) of Fe-0.45 wt.%C-1.06 wt.%Mn considering thermo-solutal convection and crystal sedimentation are performed. The modeling result indicates that the infinite liquid mixing kinetics as assumed by classical models (e.g., the Gulliver-Scheil or lever rule), which cannot properly consider the solute enrichment of the interdendritic or inter-granular melt at the early stage of solidification, might lead to an erroneous estimation of the macrosegregation. To confirm this statement, further theoretical and experimental evaluations are desired. The pattern and intensity of the flow and crystal sedimentation are dependent on the crystal morphologies (columnar or equiaxed); hence, the potential error of the calculated macrosegregation caused by the assumed growth kinetics depends on the crystal morphology. Finally, an illustrative simulation of an engineering 2.45-ton steel ingot is performed, and the results are compared with experimental results. This example demonstrates the model applicability for engineering castings regarding both the calculation efficiency and functionality.
A Macroscopic Mathematical Model for Cell Migration Assays Using a Real-Time Cell Analysis
Angelini, Claudia; Carfora, Maria Francesca; Carriero, Maria Vincenza; Natalini, Roberto
2016-01-01
Experiments of cell migration and chemotaxis assays have been classically performed in the so-called Boyden Chambers. A recent technology, xCELLigence Real Time Cell Analysis, is now allowing to monitor the cell migration in real time. This technology measures impedance changes caused by the gradual increase of electrode surface occupation by cells during the course of time and provide a Cell Index which is proportional to cellular morphology, spreading, ruffling and adhesion quality as well as cell number. In this paper we propose a macroscopic mathematical model, based on advection-reaction-diffusion partial differential equations, describing the cell migration assay using the real-time technology. We carried out numerical simulations to compare simulated model dynamics with data of observed biological experiments on three different cell lines and in two experimental settings: absence of chemotactic signals (basal migration) and presence of a chemoattractant. Overall we conclude that our minimal mathematical model is able to describe the phenomenon in the real time scale and numerical results show a good agreement with the experimental evidences. PMID:27680883
A Macroscopic Mathematical Model for Cell Migration Assays Using a Real-Time Cell Analysis.
Di Costanzo, Ezio; Ingangi, Vincenzo; Angelini, Claudia; Carfora, Maria Francesca; Carriero, Maria Vincenza; Natalini, Roberto
Experiments of cell migration and chemotaxis assays have been classically performed in the so-called Boyden Chambers. A recent technology, xCELLigence Real Time Cell Analysis, is now allowing to monitor the cell migration in real time. This technology measures impedance changes caused by the gradual increase of electrode surface occupation by cells during the course of time and provide a Cell Index which is proportional to cellular morphology, spreading, ruffling and adhesion quality as well as cell number. In this paper we propose a macroscopic mathematical model, based on advection-reaction-diffusion partial differential equations, describing the cell migration assay using the real-time technology. We carried out numerical simulations to compare simulated model dynamics with data of observed biological experiments on three different cell lines and in two experimental settings: absence of chemotactic signals (basal migration) and presence of a chemoattractant. Overall we conclude that our minimal mathematical model is able to describe the phenomenon in the real time scale and numerical results show a good agreement with the experimental evidences.
Macroscopic Model for Head-On Binary Droplet Collisions in a Gaseous Medium
NASA Astrophysics Data System (ADS)
Li, Jie
2016-11-01
In this Letter, coalescence-bouncing transitions of head-on binary droplet collisions are predicted by a novel macroscopic model based entirely on fundamental laws of physics. By making use of the lubrication theory of Zhang and Law [Phys. Fluids 23, 042102 (2011)], we have modified the Navier-Stokes equations to accurately account for the rarefied nature of the interdroplet gas film. Through the disjoint pressure model, we have incorporated the intermolecular van der Waals forces. Our model does not use any adjustable (empirical) parameters. It therefore encompasses an extreme range of length scales (more than 5 orders of magnitude): from those of the external flow in excess of the droplet size (a few hundred μ m ) to the effective range of the van der Waals force around 10 nm. A state of the art moving adaptive mesh method, capable of resolving all the relevant length scales, has been employed. Our numerical simulations are able to capture the coalescence-bouncing and bouncing-coalescence transitions that are observed as the collision intensity increases. The predicted transition Weber numbers for tetradecane and water droplet collisions at different pressures show good agreement with published experimental values. Our study also sheds new light on the roles of gas density, droplet size, and mean free path in the rupture of the gas film.
NASA Astrophysics Data System (ADS)
Liu, Baochang; Kim, Michele M.; Zhu, Timothy C.
2013-03-01
Mathematic models were developed to simulate the complex dynamic process of photodynamic therapy (PDT). Macroscopic or microscopic modeling of singlet oxygen (1O2) is particularly of interest because it is the major cytotoxic agent causing biological effects during PDT. Our previously introduced macroscopic PDT model incorporates the diffusion equation for the light propagation in tissue and the macroscopic kinetic equations for the production of the 1O2. The distance-dependent distribution of 3O2 and reacted 1O2 can be numerically calculated using finite-element method (FEM). We recently improved the model to include microscopic kinetic equations of oxygen diffusion from uniformly distributed blood vessels and within tissue. In the model, the cylindrical blood capillary has radius in the range of 2-5 μm and a mean length of 300 μm, and supplies oxygen into tissue. The blood vessel network is assumed to form a 2-D square grid perpendicular to a linear light source. The spacing of the grid is 60 μm. Oxygen can also diffuse along the radius and the longitudinal axial of the cylinder within tissue. The oxygen depletion during Photofrin-PDT PDT can be simulated using both macroscopic and microscopic approaches. The comparison of the simulation results have reasonable agreements when velocity of blood flow is reduced during PDT.
In vivo outcome study of BPD-mediated PDT using a macroscopic singlet oxygen model
NASA Astrophysics Data System (ADS)
Kim, Michele M.; Penjweini, Rozhin; Zhu, Timothy C.
2015-03-01
Macroscopic modeling of the apparent reacted singlet oxygen concentration ([1O2]rx) for use with photodynamic therapy (PDT) has been developed and studied for benzoporphryin derivative monoacid ring A (BPD), a common photosensitizer. The four photophysical parameters (ξ, σ, β, δ) and threshold singlet oxygen dose ([1O2]rx, sh) have been investigated and determined using the RIF model of murine fibrosarcomas and interstitial treatment delivery. These parameters are examined and verified further by monitoring tumor growth post-PDT. BPD was administered at 1 mg/kg, and mice were treated 3 hours later with fluence rates ranging between 75 - 150 mW/cm2 and total fluences of 100 - 350 J/cm2. Treatment was delivered superficially using a collimated beam. Changes in tumor volume were tracked following treatment. The tumor growth rate was fitted for each treatment condition group and compared using dose metrics including total light dose, PDT dose, and reacted singlet oxygen. Initial data showing the correlation between outcomes and various dose metrics indicate that reacted singlet oxygen serves as a good dosimetric quantity for predicting PDT outcome.
A macroscopic model for slightly compressible gas slip-flow in homogeneous porous media
NASA Astrophysics Data System (ADS)
Lasseux, D.; Parada, F. J. Valdes; Tapia, J. A. Ochoa; Goyeau, B.
2014-05-01
The study of gas slip-flow in porous media is relevant in many applications ranging from nanotechnology to enhanced oil recovery and in any situation involving low-pressure gas-transport through structures having sufficiently small pores. In this paper, we use the method of volume averaging for deriving effective-medium equations in the framework of a slightly compressible gas flow. The result of the upscaling process is an effective-medium model subjected to time- and length-scale constraints, which are clearly identified in our derivation. At the first order in the Knudsen number, the macroscopic momentum transport equation corresponds to a Darcy-like model involving the classical intrinsic permeability tensor and a slip-flow correction tensor that is also intrinsic. It generalizes the Darcy-Klinkenberg equation for ideal gas flow, and exhibits a more complex form for dense gas. The component values of the two intrinsic tensors were computed by solving the associated closure problems on two- and three-dimensional periodic unit cells. Furthermore, the dependence of the slip-flow correction with the porosity was also verified to agree with approximate analytical results. Our predictions show a power-law relationship between the permeability and the slip-flow correction that is consistent with other works. Nevertheless, the generalization of such a relationship to any configuration requires more analysis.
NASA Astrophysics Data System (ADS)
Bodaghi, M.; Damanpack, A. R.; Liao, W. H.
2016-07-01
The aim of this article is to develop a robust macroscopic bi-axial model to capture self-accommodation, martensitic transformation/orientation/reorientation, normal-shear deformation coupling and asymmetric/anisotropic strain generation in polycrystalline shape memory alloys. By considering the volume fraction of martensite and its preferred direction as scalar and directional internal variables, constitutive relations are derived to describe basic mechanisms of accommodation, transformation and orientation/reorientation of martensite variants. A new definition is introduced for maximum recoverable strain, which allows the model to capture the effects of tension-compression asymmetry and transformation anisotropy. Furthermore, the coupling effects between normal and shear deformation modes are considered by merging inelastic strain components together. By introducing a calibration approach, material and kinetic parameters of the model are recast in terms of common quantities that characterize a uniaxial phase kinetic diagram. The solution algorithm of the model is presented based on an elastic-predictor inelastic-corrector return mapping process. In order to explore and demonstrate capabilities of the proposed model, theoretical predictions are first compared with existing experimental results on uniaxial tension, compression, torsion and combined tension-torsion tests. Afterwards, experimental results of uniaxial tension, compression, pure bending and buckling tests on {{NiTi}} rods and tubes are replicated by implementing a finite element method along with the Newton-Raphson and Riks techniques to trace non-linear equilibrium path. A good qualitative and quantitative correlation is observed between numerical and experimental results, which verifies the accuracy of the model and the solution procedure.
Peter J. Mucha
2007-08-30
Suspensions of solid particles in liquids appear in numerous applications, from environmental settings like river silt, to industrial systems of solids transport and water treatment, and biological flows such as blood flow. Despite their importance, much remains unexplained about these complicated systems. Mucha's research aims to improve understanding of basic properties of suspensions through a program of simulating model interacting particle systems with critical evaluation of proposed continuum equations, in close collaboration with experimentalists. Natural to this approach, the original proposal centered around collaboration with studies already conducted in various experimental groups. However, as was detailed in the 2004 progress report, following the first year of this award, a number of the questions from the original proposal were necessarily redirected towards other specific goals because of changes in the research programs of the proposed experimental collaborators. Nevertheless, the modified project goals and the results that followed from those goals maintain close alignment with the main themes of the original proposal, improving efficient simulation and macroscopic modeling of sedimenting and colloidal suspensions. In particular, the main investigations covered under this award have included: (1) Sedimentation instabilities, including the sedimentation analogue of the Rayleigh-Taylor instability (for heavy, particle-laden fluid over lighter, clear fluid). (2) Ageing dynamics of colloidal suspensions at concentrations above the glass transition, using simplified interactions. (3) Stochastic reconstruction of velocity-field dependence for particle image velocimetry (PIV). (4) Stochastic modeling of the near-wall bias in 'nano-PIV'. (5) Distributed Lagrange multiplier simulation of the 'internal splash' of a particle falling through a stable stratified interface. (6) Fundamental study of velocity fluctuations in sedimentation. (7) Parallelization of
Cihan, Abdullah; Birkholzer, Jens; Trevisan, Luca; Bianchi, Marco; Zhou, Quanlin; Illangasekare, Tissa
2014-12-31
During CO_{2} injection and storage in deep reservoirs, the injected CO_{2} enters into an initially brine saturated porous medium, and after the injection stops, natural groundwater flow eventually displaces the injected mobile-phase CO_{2}, leaving behind residual non-wetting fluid. Accurate modeling of two-phase flow processes are needed for predicting fate and transport of injected CO_{2}, evaluating environmental risks and designing more effective storage schemes. The entrapped non-wetting fluid saturation is typically a function of the spatially varying maximum saturation at the end of injection. At the pore-scale, distribution of void sizes and connectivity of void space play a major role for the macroscopic hysteresis behavior and capillary entrapment of wetting and non-wetting fluids. This paper presents development of an approach based on the connectivity of void space for modeling hysteretic capillary pressure-saturation-relative permeability relationships. The new approach uses void-size distribution and a measure of void space connectivity to compute the hysteretic constitutive functions and to predict entrapped fluid phase saturations. Two functions, the drainage connectivity function and the wetting connectivity function, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model for saturation-capillary pressure is tested successfully by comparing the model-predicted residual saturation and scanning curves with actual data sets obtained from column experiments found in the literature. A numerical two-phase model simulator with the new hysteresis functions is tested against laboratory experiments conducted in a quasi-two-dimensional flow cell (91.4cm×5.6cm×61cm
Cihan, Abdullah; Birkholzer, Jens; Trevisan, Luca; ...
2014-12-31
During CO2 injection and storage in deep reservoirs, the injected CO2 enters into an initially brine saturated porous medium, and after the injection stops, natural groundwater flow eventually displaces the injected mobile-phase CO2, leaving behind residual non-wetting fluid. Accurate modeling of two-phase flow processes are needed for predicting fate and transport of injected CO2, evaluating environmental risks and designing more effective storage schemes. The entrapped non-wetting fluid saturation is typically a function of the spatially varying maximum saturation at the end of injection. At the pore-scale, distribution of void sizes and connectivity of void space play a major role formore » the macroscopic hysteresis behavior and capillary entrapment of wetting and non-wetting fluids. This paper presents development of an approach based on the connectivity of void space for modeling hysteretic capillary pressure-saturation-relative permeability relationships. The new approach uses void-size distribution and a measure of void space connectivity to compute the hysteretic constitutive functions and to predict entrapped fluid phase saturations. Two functions, the drainage connectivity function and the wetting connectivity function, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model for saturation-capillary pressure is tested successfully by comparing the model-predicted residual saturation and scanning curves with actual data sets obtained from column experiments found in the literature. A numerical two-phase model simulator with the new hysteresis functions is tested against laboratory experiments conducted in a quasi-two-dimensional flow cell (91.4cm×5.6cm×61cm), packed with homogeneous and
NASA Astrophysics Data System (ADS)
Singh, A.; Holt, R. M.; Ramarao, B.; Clemo, T.
2011-12-01
Three radioactive waste disposal landfills at the Waste Control Specialists (WCS) facility in Andrews County, Texas are constructed below grade, within the low-permeability Dockum Group mudrocks (Cooper Canyon Formation) of Triassic age. Recent site investigations at the WCS disposal facilities indicate the presence of a trapped and compressed gas phase in the mudrocks. The Dockum is a low-permeability medium with vertical and horizontal effective hydraulic conductivities of 1.2E-9 cm/s and 2.9E-7 cm/s. The upper 300+ feet of the Dockum is in the unsaturated zone, with an average saturation of 0.87 and average capillary pressure of 2.8 MPa determined from core samples. Air entry pressures on core samples range from from 0.016 to 9.8 MPa, with a mean of 1.0 MPa. Heat dissipation sensors, thermocouple psychrometers, and advanced tensiometers installed in Dockum borehole arrays generally show capillary pressures one order of magnitude less than those measured on core samples. These differences with core data are attributed to the presence of a trapped and compressed gas phase within Dockum materials. In the vicinity of an instrumented borehole, the gas phase pressure equilibrates with atmospheric pressure, lowering the capillary pressure. We have developed a new macroscopic invasion percolation (MIP) model to illustrate the origin of the trapped gas phase in the Dockum rocks. An MIP model differs from invasion percolation (IP) through the definition of macro-scale capillarity. Individual pore throats and necks are not considered. Instead, a near pore-scale block is defined and characterized by a local threshold spanning pressure (a local block-scale breakthrough pressure) that represents the behavior of the subscale network. The model domain is discretized into an array of grid blocks with assigned spanning pressures. An invasion pressure for each block is then determined by the sum of spanning pressure, buoyance forces, and viscous forces. An IP algorithm sorts the
Jakovljevic, Djordje G; Moore, Sarah; Hallsworth, Kate; Fattakhova, Gulnar; Thoma, Christian; Trenell, Michael I
2012-04-01
Bioreactance is a novel non-invasive method for cardiac output measurement that involves the analysis of blood flow-dependent changes in the phase shifts of electrical currents applied across the chest. The present study (1) compared resting and exercise cardiac outputs determined by bioreactance and bioimpedance methods and those estimated from measured oxygen consumption, (2) determined the relationship between cardiac output and oxygen consumption, and (3) assessed the agreement between the bioreactance and bioimpedance methods. Twelve healthy subjects (aged 30 ± 4 years) performed graded cardiopulmonary exercise test on a recumbent cycle ergometer on two occasions, 1 week apart. Cardiac output was monitored at rest, at 30, 50, 70, 90, 150 W and at peak exercise intensity by bioreactance and bioimpedance and expired gases collected. Resting cardiac output was not significantly different between the bioreactance and bioimpedance methods (6.2 ± 1.4 vs. 6.5 ± 1.4 l min(-1), P = 0.42). During exercise cardiac outputs were correlated with oxygen uptake for both bioreactance (r = 0.84, P < 0.01) and bioimpedance techniques (r = 0.82, P < 0.01). At peak exercise bioimpedance estimated significantly lower cardiac outputs than both bioreactance and theoretically calculated cardiac output (14.3 ± 2.6 vs. 17.5 ± 5.2 vs. 16.9 ± 4.9 l min(-1), P < 0.05). Bland-Altman analyses including data from rest and exercise demonstrated that the bioimpedance method reported ~1.5 l min(-1) lower cardiac output than bioreactance with lower and upper limits of agreement of -2.98 to 5.98 l min(-1). Bioimpedance and bioreactance methods provide different cardiac output estimates, particularly at high exercise intensity, and therefore the two methods cannot be used interchangeably. In contrast with bioimpedance, bioreactance cardiac outputs are similar to those estimated from measured oxygen consumption.
NASA Astrophysics Data System (ADS)
Mittnenzweig, Markus; Mielke, Alexander
2017-03-01
We show that all Lindblad operators (i.e., generators of quantum Markov semigroups) on a finite-dimensional Hilbert space satisfying the detailed balance condition with respect to the thermal equilibrium state can be written as a gradient system with respect to the relative entropy. We discuss also thermodynamically consistent couplings to macroscopic systems, either as damped Hamiltonian systems with constant temperature or as GENERIC systems.
Heterogeneous traffic flow modelling using second-order macroscopic continuum model
NASA Astrophysics Data System (ADS)
Mohan, Ranju; Ramadurai, Gitakrishnan
2017-01-01
Modelling heterogeneous traffic flow lacking in lane discipline is one of the emerging research areas in the past few years. The two main challenges in modelling are: capturing the effect of varying size of vehicles, and the lack in lane discipline, both of which together lead to the 'gap filling' behaviour of vehicles. The same section length of the road can be occupied by different types of vehicles at the same time, and the conventional measure of traffic concentration, density (vehicles per lane per unit length), is not a good measure for heterogeneous traffic modelling. First aim of this paper is to have a parsimonious model of heterogeneous traffic that can capture the unique phenomena of gap filling. Second aim is to emphasize the suitability of higher-order models for modelling heterogeneous traffic. Third, the paper aims to suggest area occupancy as concentration measure of heterogeneous traffic lacking in lane discipline. The above mentioned two main challenges of heterogeneous traffic flow are addressed by extending an existing second-order continuum model of traffic flow, using area occupancy for traffic concentration instead of density. The extended model is calibrated and validated with field data from an arterial road in Chennai city, and the results are compared with those from few existing generalized multi-class models.
NASA Astrophysics Data System (ADS)
Shin, Yong Hyeon; Yun, Ilgu
2016-12-01
An analytical model is proposed for the random dopant fluctuation (RDF) in a symmetric double-gate metal-oxidesemiconductor field-effect-transistor (DG MOSFET) in the subthreshold region. Unintended impurity dopants cannot be absolutely prevented during the device fabrication; hence, it is important to analytically model the fluctuations in the electrical characteristics caused by these impurity dopants. Therefore, a macroscopic modeling method is applied to represent the impurity dopants in DG MOSFETs. With this method, the two-dimensional (2D) Poisson equation is separated into a basic analytical DG MOSFET model with channel doping concentration NA and an impurity-dopant-related term with local doping concentration NRD confined in a specific rectangular area. To solve the second term, the manually solvable 2D Green's function for DG MOSFETs is used. Through calculation of the channel potential (ϕ(x, y)), the variations in the drive current (IDS) and threshold voltage (Vth) are extracted from the analytical model. All results from the analytical model for an impurity dopant in a DG MOSFET are examined by comparisons with the commercially available 2D numerical simulation results, with respect to various oxide thicknesses (tox), channel lengths (L), and location of impurity dopants.
Droplet-based microsystem for multi-step bioreactions.
Wang, Fang; Burns, Mark A
2010-06-01
A droplet-based microfluidic platform was used to perform on-chip droplet generation, merging and mixing for applications in multi-step reactions and assays. Submicroliter-sized droplets can be produced separately from three identical droplet-generation channels and merged together in a single chamber. Three different mixing strategies were used for mixing the merged droplet. For pure diffusion, the reagents were mixed in approximately 10 min. Using flow around the stationary droplet to induce circulatory flow within the droplet, the mixing time was decreased to approximately one minute. The shortest mixing time (10 s) was obtained with bidirectional droplet motion between the chamber and channel, and optimization could result in a total time of less than 1 s. We also tested this on-chip droplet generation and manipulation platform using a two-step thermal cycled bioreaction: nested TaqMan PCR. With the same concentration of template DNA, the two-step reaction in a well-mixed merged droplet shows a cycle threshold of approximately 6 cycles earlier than that in the diffusively mixed droplet, and approximately 40 cycles earlier than the droplet-based regular (single-step) TaqMan PCR.
NASA Astrophysics Data System (ADS)
Raju, Subramanian; Saibaba, Saroja
2016-09-01
The enthalpy of formation Δo H f is an important thermodynamic quantity, which sheds significant light on fundamental cohesive and structural characteristics of an alloy. However, being a difficult one to determine accurately through experiments, simple estimation procedures are often desirable. In the present study, a modified prescription for estimating Δo H f L of liquid transition metal alloys is outlined, based on the Macroscopic Atom Model of cohesion. This prescription relies on self-consistent estimation of liquid-specific model parameters, namely electronegativity ( ϕ L) and bonding electron density ( n b L ). Such unique identification is made through the use of well-established relationships connecting surface tension, compressibility, and molar volume of a metallic liquid with bonding charge density. The electronegativity is obtained through a consistent linear scaling procedure. The preliminary set of values for ϕ L and n b L , together with other auxiliary model parameters, is subsequently optimized to obtain a good numerical agreement between calculated and experimental values of Δo H f L for sixty liquid transition metal alloys. It is found that, with few exceptions, the use of liquid-specific model parameters in Macroscopic Atom Model yields a physically consistent methodology for reliable estimation of mixing enthalpies of liquid alloys.
NASA Technical Reports Server (NTRS)
Ripoll, J.-F.; Wray, A. A.
2003-01-01
In this paper a new three dimensional half-moment model for radiative transfer is presented for a gray medium. It describes the evolution of the zeroth and first directional half moments of the radiative intensity. The closure is provided, similarly to Dubroca and Klar, by the maximum entropy concept. This work generalizes that model to three dimensions. The model presented here (the derivation being done in Ripoll and Wray, called the M(sup 1/2)(sub 1) model, is a hyperbolic system consisting of a total of eight equations in three dimensions, four equations for each direction. Each half model has the classical form of a macroscopic moment model in which the pressure tensor is constructed from the well-known Eddington tensor with a particular Eddington factor. Moreover, different source and border terms occur. The latter introduce couplings between the macroscopic and microscopic quantities and between the + and - streams, through the intensity in the plane perpendicular to the flux. The main theoretical application of the half moment model, treated in this paper, is its reduction to a full moment model, called M(sup +)(sub 1), for the particular but important case of a hot, opaque source radiating in a cold transparent (or semi-transparent) medium for very specific applications, such as stellar interiors or atmospheres, or combustion problems. The structure of the paper is as follows. In section 2, the model M(sup 1/2)(sub 1) is presented. In section 3, for the particular case of a hot, opaque source radiating into a cold medium, the half moment model is reduced to the M(sup +)(sub 1) model. In section 4, we first solve a simple and academic problem to validate the models, followed by a simplified solar atmosphere.
Duckworth, Owen W.; Cygan, Randall Timothy; Martin, Scot T.
2004-05-01
Bulk and surface energies are calculated for endmembers of the isostructural rhombohedral carbonate mineral family, including Ca, Cd, Co, Fe, Mg, Mn, Ni, and Zn compositions. The calculations for the bulk agree with the densities, bond distances, bond angles, and lattice enthalpies reported in the literature. The calculated energies also correlate with measured dissolution rates: the lattice energies show a log-linear relationship to the macroscopic dissolution rates at circumneutral pH. Moreover, the energies of ion pairs translated along surface steps are calculated and found to predict experimentally observed microscopic step retreat velocities. Finally, pit formation excess energies decrease with increasing pit size, which is consistent with the nonlinear dissolution kinetics hypothesized for the initial stages of pit formation.
Connecting Pore Scale Dynamics to Macroscopic Models for Two-Fluid Phase Flow
NASA Astrophysics Data System (ADS)
McClure, J. E.; Dye, A. L.; Miller, C. T.; Gray, W. G.
2015-12-01
Imaging technologies such as computed micro-tomography (CMT) provide high resolution three-dimensional images of real porous medium systems that reveal the true geometric structure of fluid and solid phases. Simulation and analysis tools are essential to extract knowledge from this raw data, and can be applied in tandem to provide information that is otherwise inaccessible. Guidance from multi-scale averaging theory is used to develop a multi-scale analysis framework to determine phase connectivity and extract interfacial areas, curvatures, common line length, contact angle and the velocities of the interface and common curve. The approach is applied to analyze pore-scale dynamics based on a multiphase lattice Boltzmann method. Dense sets of simulations are performed to evaluate the equilibrium relationship between capillary pressure, saturation and interfacial area for several experimentally imaged porous media. The approach is also used study the evolution of macroscopic quantities under dynamic conditions, which is compared to the equilibrium data.
Interaction of nanoparticles with proteins: relation to bio-reactivity of the nanoparticle.
Saptarshi, Shruti R; Duschl, Albert; Lopata, Andreas L
2013-07-19
Interaction of nanoparticles with proteins is the basis of nanoparticle bio-reactivity. This interaction gives rise to the formation of a dynamic nanoparticle-protein corona. The protein corona may influence cellular uptake, inflammation, accumulation, degradation and clearance of the nanoparticles. Furthermore, the nanoparticle surface can induce conformational changes in adsorbed protein molecules which may affect the overall bio-reactivity of the nanoparticle. In depth understanding of such interactions can be directed towards generating bio-compatible nanomaterials with controlled surface characteristics in a biological environment. The main aim of this review is to summarise current knowledge on factors that influence nanoparticle-protein interactions and their implications on cellular uptake.
Penjweini, Rozhin; Liu, Baochang; Kim, Michele M.; Zhu, Timothy C.
2015-01-01
Abstract. Type II photodynamic therapy (PDT) is based on the photochemical reactions mediated through an interaction between a photosensitizer, ground-state oxygen ([O32]), and light excitation at an appropriate wavelength, which results in production of reactive singlet oxygen ([O12]rx). We use an empirical macroscopic model based on four photochemical parameters for the calculation of [O12]rx threshold concentration ([O12]rx,sh) causing tissue necrosis in tumors after PDT. For this reason, 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH)-mediated PDT was performed interstitially on mice with radiation-induced fibrosarcoma (RIF) tumors. A linear light source at 665 nm with total energy released per unit length of 12 to 100 J/cm and source power per unit length (LS) of 12 to 150 mW/cm was used to induce different radii of necrosis. Then the amount of [O12]rx calculated by the macroscopic model incorporating explicit PDT dosimetry of light fluence distribution, tissue optical properties, and HPPH concentration was correlated to the necrotic radius to obtain the model parameters and [O12]rx,sh. We provide evidence that [O12]rx is a better dosimetric quantity for predicting the treatment outcome than PDT dose, which is proportional to the time integral of the products of the photosensitizer concentration and light fluence rate. PMID:26720883
NASA Astrophysics Data System (ADS)
Penjweini, Rozhin; Liu, Baochang; Kim, Michele M.; Zhu, Timothy C.
2015-12-01
Type II photodynamic therapy (PDT) is based on the photochemical reactions mediated through an interaction between a photosensitizer, ground-state oxygen ([O]), and light excitation at an appropriate wavelength, which results in production of reactive singlet oxygen ([]rx). We use an empirical macroscopic model based on four photochemical parameters for the calculation of []rx threshold concentration ([]rx,sh) causing tissue necrosis in tumors after PDT. For this reason, 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH)-mediated PDT was performed interstitially on mice with radiation-induced fibrosarcoma (RIF) tumors. A linear light source at 665 nm with total energy released per unit length of 12 to 100 J/cm and source power per unit length (LS) of 12 to 150 mW/cm was used to induce different radii of necrosis. Then the amount of []rx calculated by the macroscopic model incorporating explicit PDT dosimetry of light fluence distribution, tissue optical properties, and HPPH concentration was correlated to the necrotic radius to obtain the model parameters and []rx,sh. We provide evidence that []rx is a better dosimetric quantity for predicting the treatment outcome than PDT dose, which is proportional to the time integral of the products of the photosensitizer concentration and light fluence rate.
Continuous Feedback and Macroscopic Coherence
NASA Technical Reports Server (NTRS)
Tombesi, Paolo; Vitali, David
1996-01-01
We show that a model, recently introduced for quantum nondemolition measurements of a quantum observable, can be adapted to obtain a measurement scheme which is able to slow down the destruction of macroscopic coherence due to the measurement apparatus.
This report is a generic test plan for bioreaction systems that use biological tools to act as contaminant sorbers and biodegraders. These are usually biofilters and bioreactors which are packed bed reactors using peat, soil, etc., biotrickling filters which handle liquid phase ...
NASA Astrophysics Data System (ADS)
Calonne, N.; Geindreau, C.; Flin, F.
2015-12-01
At the microscopic scale, i.e., pore scale, dry snow metamorphism is mainly driven by the heat and water vapor transfer and the sublimation-deposition process at the ice-air interface. Up to now, the description of these phenomena at the macroscopic scale, i.e., snow layer scale, in the snowpack models has been proposed in a phenomenological way. Here we used an upscaling method, namely, the homogenization of multiple-scale expansions, to derive theoretically the macroscopic equivalent modeling of heat and vapor transfer through a snow layer from the physics at the pore scale. The physical phenomena under consideration are steady state air flow, heat transfer by conduction and convection, water vapor transfer by diffusion and convection, and phase change (sublimation and deposition). We derived three different macroscopic models depending on the intensity of the air flow considered at the pore scale, i.e., on the order of magnitude of the pore Reynolds number and the Péclet numbers: (A) pure diffusion, (B) diffusion and moderate convection (Darcy's law), and (C) strong convection (nonlinear flow). The formulation of the models includes the exact expression of the macroscopic properties (effective thermal conductivity, effective vapor diffusion coefficient, and intrinsic permeability) and of the macroscopic source terms of heat and vapor arising from the phase change at the pore scale. Such definitions can be used to compute macroscopic snow properties from 3-D descriptions of snow microstructures. Finally, we illustrated the precision and the robustness of the proposed macroscopic models through 2-D numerical simulations.
NASA Astrophysics Data System (ADS)
Porporato, A. M.; Parolari, A.
2015-12-01
Ecohydrological processes in the root zone act as a dynamic interface between the atmosphere and the deeper soil layers, modulating the conditions that drive chemical weathering along the soil profile. Among these processes, soil moisture dynamics respond to intermittent rainfall pulses and to runoff and evapotranspiration losses. In addition, carbon dioxide (CO2) and its associated acidity are introduced into the soil moisture via root and microbial respiration. The coupling of soil moisture and CO2 dynamics in the root zone acts as an important controller of the critical zone development through the chemical weathering and water chemistry exported through runoff and percolation. Due to spatial and temporal variability and non-linearity, modeling these coupled root zone soil moisture and CO2 dynamics presents a number of challenges. In this talk, a lumped, macroscopic approach to modeling soil moisture, CO2 transport, and chemical weathering in the critical zone is introduced. The model considers a homogeneous soil column, therefore simplifying known spatial heterogeneities, and focuses on temporal variability resulting from non-linear processes and stochastic rainfall forcing. First, at short time-scales, the deterministic temporal evolution of soil moisture, dissolved inorganic carbon, pH, and alkalinity is analyzed using a dynamical system approach. Second, at longer inter-annual time-scales where rainfall stochasticity becomes an important driver of the system behavior, the system is analyzed probabilistically and its average behavior described using a novel macroscopic approach. This averaging of the nonlinear stochastic dynamics results in a closure problem that is addressed through a first-order approximation of non-linear fluxes, including the correlation between soil moisture and solutes. The model provides a method to assess how changes in external forcing or system properties propagate into and alter critical zone structure and function, and to isolate
Macroscopic constraints on string unification
Taylor, T.R.
1989-03-01
The comparison of sting theory with experiment requires a huge extrapolation from the microscopic distances, of order of the Planck length, up to the macroscopic laboratory distances. The quantum effects give rise to large corrections to the macroscopic predictions of sting unification. I discus the model-independent constraints on the gravitational sector of string theory due to the inevitable existence of universal Fradkin-Tseytlin dilatons. 9 refs.
Doutres, O; Ouisse, M; Atalla, N; Ichchou, M
2014-10-01
This paper deals with the prediction of the macroscopic sound absorption behavior of highly porous polyurethane foams using two unit-cell microstructure-based models recently developed by Doutres, Atalla, and Dong [J. Appl. Phys. 110, 064901 (2011); J. Appl. Phys. 113, 054901 (2013)]. In these models, the porous material is idealized as a packing of a tetrakaidecahedra unit-cell representative of the disordered network that constitutes the porous frame. The non-acoustic parameters involved in the classical Johnson-Champoux-Allard model (i.e., porosity, airflow resistivity, tortuosity, etc.) are derived from characteristic properties of the unit-cell and semi-empirical relationships. A global sensitivity analysis is performed on these two models in order to investigate how the variability associated with the measured unit-cell characteristics affects the models outputs. This allows identification of the possible limitations of a unit-cell micro-macro approach due to microstructure irregularity. The sensitivity analysis mainly shows that for moderately and highly reticulated polyurethane foams, the strut length parameter is the key parameter since it greatly impacts three important non-acoustic parameters and causes large uncertainty on the sound absorption coefficient even if its measurement variability is moderate. For foams with a slight inhomogeneity and anisotropy, a micro-macro model associated to cell size measurements should be preferred.
NASA Astrophysics Data System (ADS)
Hoogendoorn, Serge P.; van Wageningen-Kessels, Femke L. M.; Daamen, Winnie; Duives, Dorine C.
2014-12-01
The dynamics of pedestrian flows can be captured in a continuum modelling framework. However, compared to vehicular flow, this is a much more challenging task. In particular the integration of flow propagation and path choice are known to be problematic. Furthermore, pedestrian flow is characterised by different self-organised phenomena, such as the formation of dynamic lanes and diagonal stripes, which have not yet been captured in a continuum modelling framework. This contribution puts forward a novel multi-class continuum model that captures some of the key features of pedestrian flows. It considers path choice behaviour on both the strategic (pre-trip) and tactical (en-route) level. To achieve this, we present a methodology to derive a continuum model from a microscopic walker model, in this case the social forces model. In doing so, we show that the interaction term present in the social forces model introduces a local path choice component in the equilibrium velocity. Having derived the model, we analyse its properties both by means of mathematical analyses and simulation studies. This reveals the general behaviour of the model, as well as the ability of the model to reproduce self-organised structures, and phase transitions. To the best of our knowledge, this is the first continuum model that is able to reproduce these self-organised structures.
Macroscopic modeling of pedestrian and bicycle crashes: A cross-comparison of estimation methods.
Amoh-Gyimah, Richard; Saberi, Meead; Sarvi, Majid
2016-08-01
The paper presents a cross-comparison of different estimation methods to model pedestrian and bicycle crashes. The study contributes to macro level safety studies by providing further methodological and empirical evidence on the various factors that influence the frequency of pedestrian and bicycle crashes at the planning level. Random parameter negative binomial (RPNB) models are estimated to explore the effects of various planning factors associated with total, serious injury and minor injury crashes while accounting for unobserved heterogeneity. Results of the RPNB models were compared with the results of a non-spatial negative binomial (NB) model and a Poisson-Gamma-CAR model. Key findings are, (1) the RPNB model performed best with the lowest mean absolute deviation, mean squared predicted error and Akaiki information criterion measures and (2) signs of estimated parameters are consistent if these variables are significant in models with the same response variables. We found that vehicle kilometers traveled (VKT), population, percentage of commuters cycling or walking to work, and percentage of households without motor vehicles have a significant and positive correlation with the number of pedestrian and bicycle crashes. Mixed land use is also found to have a positive association with the number of pedestrian and bicycle crashes. Results have planning and policy implications aimed at encouraging the use of sustainable modes of transportation while ensuring the safety of pedestrians and cyclist.
Lin, Chichung; Arakawa, Akio
1997-04-15
According to Part I of this paper, is seems that ignoring the contribution from descendent cloud air in a cloud model for cumulus parameterization (CMCP), such as the spectral cumulus ensemble model in the Arakawa-Schubert parameterization, is an acceptable simplification for tropical deep convection. Since each subensemble in the spectral cumulus ensemble model is formally analogous to an entraining plume, the latter is examined using the simulated data from a cloud-resolving model (CRM). The authors first follow the analysis procedure of Warner. With the data from a nonprecipitating experiment, the authors show that the entraining-plume model cannot simultaneously predict the mean liquid water profile and cloud top height of the clouds simulated by the CRM. However, the mean properties of active elements of clouds, which are characterized by strong updrafts, can be described by an entraining plume of similar top height. With data from a precipitating experiment, the authors examine the spectral cumulus ensemble model using the Paluch diagram. It is found that the spectral cumulus ensemble model appears adequate if different types of clouds in the spectrum are interpreted as subcloud elements with different entrainment characteristics. The resolved internal structure of clouds can thus be viewed as a manifestation of a cloud spectrum. To further investigate whether the fractional rate of entrainment is an appropriate parameter for characterizing cloud types in the spectral cumulus ensemble model, the authors stratify the simulated saturated updrafts (subcloud elements) into different types according to their eventual heights and calculate the cloud mass flux and mean moist static energy for each type. Entrainment characteristics are then inferred through the cloud mass flux and in-cloud moist static energy. It is found that different types of subcloud elements have distinguishable thermodynamic properties and entrainment characteristics. 16 refs., 8 figs.
NASA Astrophysics Data System (ADS)
Chatterjee, Saikat; Chattopadhyay, Kinnor
2016-10-01
Open eye formation in tundishes can result in reoxidation of liquid steel leading to the formation of harmful inclusions. Moreover, it is also a site for heat loss, gas absorption, and slag emulsification. All these factors make it necessary to understand the fundamentals of open eye formation, which in turn will allow us to prevent or control its harmful effects. In the present study, the bubble plume regions in a ladle and tundish were compared, and it was observed that there are significant differences between the two. Moreover, a simplistic model for predicting the open eye area in tundishes for `thin slag' practices was derived using the principles of conservation of mass and momentum. The proposed model was able to predict open eye areas in tundish reasonably well and was compared with other models, and experimental results.
Bioreactivity of municipal solid waste landfill leachates-Hormesis and DNA damage.
Koshy, Lata; Jones, Tim; BéruBé, Kelly
2008-04-01
The issue of domestic waste is recognised as one of the most serious environmental problems facing the nation. With the UK producing 35 million tonnes of municipal solid waste per annum, an understanding of the ranges of toxicity of landfill emissions is crucial to determine the degree of concern we should have about the potential effects these waste sites could have upon nearby populations and the surrounding environment. The aim of this study was to evaluate the bioreactivity of landfill leachates in terms of their capacity to damage ROS-sensitive bacteriophage plasmid DNA and induce toxicity in a commercial photobacterium toxicity assay, based on the light emission of Vibrio fischeri bacteria (ROTAS). The bacterial assay revealed widespread biostimulation and a hormesis response in the bacteria, with alpha-, beta- and gamma-response curves observed following exposure to the different landfill leachates. Different biological mechanisms lead to variations in bioreactivity, as seen in the plasmid DNA scission and ROTAS assays.
A phenomenological cohesive model for the macroscopic simulation of cell-matrix adhesions.
Cóndor, M; García-Aznar, J M
2017-02-17
Cell adhesion is crucial for cells to not only physically interact with each other but also sense their microenvironment and respond accordingly. In fact, adherent cells can generate physical forces that are transmitted to the surrounding matrix, regulating the formation of cell-matrix adhesions. The main purpose of this work is to develop a computational model to simulate the dynamics of cell-matrix adhesions through a cohesive formulation within the framework of the finite element method and based on the principles of continuum damage mechanics. This model enables the simulation of the mechanical adhesion between cell and extracellular matrix (ECM) as regulated by local multidirectional forces and thus predicts the onset and growth of the adhesion. In addition, this numerical approach allows the simulation of the cell as a whole, as it models the complete mechanical interaction between cell and ECM. As a result, we can investigate and quantify how different mechanical conditions in the cell (e.g., contractile forces, actin cytoskeletal properties) or in the ECM (e.g., stiffness, external forces) can regulate the dynamics of cell-matrix adhesions.
From Stories to Scientific Models and Back: Narrative framing in modern macroscopic physics
NASA Astrophysics Data System (ADS)
Fuchs, Hans U.
2015-04-01
Narrative in science learning has become an important field of inquiry. Most applications of narrative are extrinsic to science-such as when they are used for creating affect and context. Where they are intrinsic, they are often limited to special cases and uses. To extend the reach of narrative in science, a hypothesis of narrative framing of natural and technical scenes is formulated. The term narrative framing is used in a double sense, to represent (1) the enlisting of narrative intelligence in the perception of phenomena and (2) the telling of stories that contain conceptual elements used in the creation of scientific models of these phenomena. The concrete case for narrative framing is made by conceptual analyses of simple stories of natural phenomena and of products related to modern continuum thermodynamics that reveal particular figurative structures. Importantly, there is evidence for a medium-scale perceptual gestalt called force of nature that is structured metaphorically and narratively. The resulting figurative conceptual structure gives rise to the notion of natural agents acting and suffering in storyworlds. In order to show that formal scientific models are deeply related to these storyworlds, a link between using (i.e. simulating) models and storytelling is employed. This link has recently been postulated in studies of narrative in computational science and economics.
A three-dimensional meso-macroscopic model for Li-Ion intercalation batteries
NASA Astrophysics Data System (ADS)
Allu, S.; Kalnaus, S.; Simunovic, S.; Nanda, J.; Turner, J. A.; Pannala, S.
2016-09-01
In this paper we present a three-dimensional computational formulation for electrode-electrolyte-electrode system of Li-Ion batteries. The physical consistency between electrical, thermal and chemical equations is enforced at each time increment by driving the residual of the resulting coupled system of nonlinear equations to zero. The formulation utilizes a rigorous volume averaging approach typical of multiphase formulations used in other fields and recently extended to modeling of supercapacitors [1]. Unlike existing battery modeling methods which use segregated solution of conservation equations and idealized geometries, our unified approach can model arbitrary battery and electrode configurations. The consistency of multi-physics solution also allows for consideration of a wide array of initial conditions and load cases. The formulation accounts for spatio-temporal variations of material and state properties such as electrode/void volume fractions and anisotropic conductivities. The governing differential equations are discretized using the finite element method and solved using a nonlinearly consistent approach that provides robust stability and convergence. The new formulation was validated for standard Li-ion cells and compared against experiments. Its scope and ability to capture spatio-temporal variations of potential and lithium distribution is demonstrated on a prototypical three-dimensional electrode problem.
A three-dimensional meso-macroscopic model for Li-Ion intercalation batteries
Allu, S.; Kalnaus, S.; Simunovic, S.; Nanda, J.; Turner, J. A.; Pannala, S.
2016-06-09
Through this study, we present a three-dimensional computational formulation for electrode-electrolyte-electrode system of Li-Ion batteries. The physical consistency between electrical, thermal and chemical equations is enforced at each time increment by driving the residual of the resulting coupled system of nonlinear equations to zero. The formulation utilizes a rigorous volume averaging approach typical of multiphase formulations used in other fields and recently extended to modeling of supercapacitors [1]. Unlike existing battery modeling methods which use segregated solution of conservation equations and idealized geometries, our unified approach can model arbitrary battery and electrode configurations. The consistency of multi-physics solution also allows for consideration of a wide array of initial conditions and load cases. The formulation accounts for spatio-temporal variations of material and state properties such as electrode/void volume fractions and anisotropic conductivities. The governing differential equations are discretized using the finite element method and solved using a nonlinearly consistent approach that provides robust stability and convergence. The new formulation was validated for standard Li-ion cells and compared against experiments. Finally, its scope and ability to capture spatio-temporal variations of potential and lithium distribution is demonstrated on a prototypical three-dimensional electrode problem.
A three-dimensional meso-macroscopic model for Li-Ion intercalation batteries
Allu, S.; Kalnaus, S.; Simunovic, S.; ...
2016-06-09
Through this study, we present a three-dimensional computational formulation for electrode-electrolyte-electrode system of Li-Ion batteries. The physical consistency between electrical, thermal and chemical equations is enforced at each time increment by driving the residual of the resulting coupled system of nonlinear equations to zero. The formulation utilizes a rigorous volume averaging approach typical of multiphase formulations used in other fields and recently extended to modeling of supercapacitors [1]. Unlike existing battery modeling methods which use segregated solution of conservation equations and idealized geometries, our unified approach can model arbitrary battery and electrode configurations. The consistency of multi-physics solution also allowsmore » for consideration of a wide array of initial conditions and load cases. The formulation accounts for spatio-temporal variations of material and state properties such as electrode/void volume fractions and anisotropic conductivities. The governing differential equations are discretized using the finite element method and solved using a nonlinearly consistent approach that provides robust stability and convergence. The new formulation was validated for standard Li-ion cells and compared against experiments. Finally, its scope and ability to capture spatio-temporal variations of potential and lithium distribution is demonstrated on a prototypical three-dimensional electrode problem.« less
Application of bioreactance for cardiac output assessment during exercise in healthy individuals.
Elliott, Adrian; Hull, James H; Nunan, David; Jakovljevic, Djordje G; Brodie, David; Ansley, Lesley
2010-07-01
In patients with cardiac failure, bioreactance-based cardiac output (CO) monitoring provides a valid non-invasive method for assessing cardiac performance during exercise. The purpose of this study was to evaluate the efficacy of this technique during strenuous exercise in healthy, trained individuals. Fourteen recreational cyclists, mean (SD) age of 34 (8) years and relative peak oxygen uptake of (VO(2)) 56 (6) ml kg(-1) min(-1), underwent incremental maximal exercise testing, whilst CO was recorded continuously using a novel bioreactance-based device (CO(bio)). The CO(bio) was evaluated against relationship with VO(2), theoretical calculation of arterial-venous oxygen difference (C(a - v) O(2)) and level of agreement with an inert gas rebreathing method (CO(rb)) using a Bland-Altman plot. Bioreactance-based CO measurement was practical and straightforward in application, although there was intermittent loss of electrocardiograph signal at high-intensity exercise. At rest and during exercise, CO(bio) was strongly correlated with VO(2) (r = 0.84; P < 0.001), however, there was evidence of systematic bias with CO(bio) providing lower values than CO(rb); mean bias (limits of agreement) -19% (14.6 to -53%). Likewise, calculated (C(a - v) O(2)) was greater when determined using CO(bio) than CO(rb) (P < 0.001), although both devices provided values in excess of those reported in invasive studies. Bioreactance-based determination of CO provides a pragmatic approach to the continuous assessment of cardiac performance during strenuous exercise in trained individuals. Our findings, however, suggest that further work is needed to refine the key measurement determinants of CO using this device to improve measurement accuracy in this setting.
Contreras-Vite, Juan A; Cruz-Rangel, Silvia; De Jesús-Pérez, José J; Figueroa, Iván A Aréchiga; Rodríguez-Menchaca, Aldo A; Pérez-Cornejo, Patricia; Hartzell, H Criss; Arreola, Jorge
2016-07-01
TMEM16A (ANO1), the pore-forming subunit of calcium-activated chloride channels, regulates several physiological and pathophysiological processes such as smooth muscle contraction, cardiac and neuronal excitability, salivary secretion, tumour growth and cancer progression. Gating of TMEM16A is complex because it involves the interplay between increases in intracellular calcium concentration ([Ca(2+)]i), membrane depolarization, extracellular Cl(-) or permeant anions and intracellular protons. Our goal here was to understand how these variables regulate TMEM16A gating and to explain four observations. (a) TMEM16A is activated by voltage in the absence of intracellular Ca(2+). (b) The Cl(-) conductance is decreased after reducing extracellular Cl(-) concentration ([Cl(-)]o). (c) ICl is regulated by physiological concentrations of [Cl(-)]o. (d) In cells dialyzed with 0.2 μM [Ca(2+)]i, Cl(-) has a bimodal effect: at [Cl(-)]o <30 mM TMEM16A current activates with a monoexponential time course, but above 30 mM, [Cl(-)]o ICl activation displays fast and slow kinetics. To explain the contribution of Vm, Ca(2+) and Cl(-) to gating, we developed a 12-state Markov chain model. This model explains TMEM16A activation as a sequential, direct, and Vm-dependent binding of two Ca(2+) ions coupled to a Vm-dependent binding of an external Cl(-) ion, with Vm-dependent transitions between states. Our model predicts that extracellular Cl(-) does not alter the apparent Ca(2+) affinity of TMEM16A, which we corroborated experimentally. Rather, extracellular Cl(-) acts by stabilizing the open configuration induced by Ca(2+) and by contributing to the Vm dependence of activation.
Asymptotic Modeling of Flows in Micro-Channel by Using Macroscopic Balance Equations
NASA Astrophysics Data System (ADS)
Gatignol, Renée; Croizet, Cédric
2011-05-01
The introduction of a small parameter related to a micro-channel geometry and the application of the Principle of Least Degeneracy to the dimensionless Navier-Stokes equations produce models for the study of micro-channel flows with small Mach number and small or moderate Knudsen number. The first approximation of the asymptotic solution is calculated for a steady gas flow inside a micro-channel with a temperature gradient along the walls. In addition, Direct Simulation Monte Carlo (DSMC) method is used to analyze the same problem and some comparisons are presented. Analytical asymptotic solutions and DSMC numerical simulations found to be in very good agreement.
Macroscopic Modeling of A3B15A3 Triblock Copolymers in B Solvent
2010-11-01
collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources...information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1 . REPORT DATE (DD...Acknowledgements v 1 . Introduction 1 2. Models and Methods 2 3. Results and Discussion 3 4. Conclusion 9 5. References 11 List of Symbols
Rankin, Blake M; Ben-Amotz, Dor; Widom, B
2015-09-14
Molecular processes, ranging from hydrophobic aggregation and protein binding to mesoscopic self-assembly, are typically driven by a delicate balance of energetic and entropic non-covalent interactions. Here, we focus on a broad class of such processes in which multiple ligands bind to a central solute molecule as a result of solute-ligand (direct) and/or ligand-ligand (cooperative) interaction energies. Previously, we described a weighted random mixing (WRM) mean-field model for such processes and compared the resulting adsorption isotherms and aggregate size distributions with exact finite lattice (FL) predictions, for lattices with up to n = 20 binding sites. Here, we compare FL predictions obtained using both Bethe-Guggenheim (BG) and WRM approximations, and find that the latter two approximations are complementary, as they are each most accurate in different aggregation regimes. Moreover, we describe a computationally efficient method for exhaustively counting nearest neighbors in FL configurations, thus making it feasible to obtain FL predictions for systems with up n = 48 binding sites, whose properties approach the thermodynamic (infinite lattice) limit. We further illustrate the applicability of our results by comparing lattice model and molecular dynamics simulation predictions pertaining to the aggregation of methane around neopentane.
Ryan, M.P.; Koyanagi, R.Y.; Fiske, R.S.
1981-08-10
We report the results of modeling the three-dimensional internal structure of Kilauea's magmatic passageways. The approach uses a clear plexiglass model containing equally-spaced levels upon which well-located seismic hypocenters are plotted. Application of constraining geologic and geophysical criteria to this distributed volume of earthquakes permits the interpretation of seismic structures produced by fracturing in response to locally high fluid pressures. Four magma transport and storage structures produce have been identified within and beneath Kilauea: (1) Primary conduit. The conduit transporting magma into Kilauea's summit storage reservoir rises from the model base (14.6 km) to 6.5 km depth level. It is a zone of intense fracturing and inferred intrusion, whose horizontal sections are elliptical in planform. Over its height, the average major axis of component horizontal section is 3.3 km, with an average minor axis of 1.7 km. This yields an aspect ratio of xi = 0.52. At the 14.6 km level, the strike of the major axis is N67 /sup 0/E. During passage from the upper mantle through the oceanic crust, this axis rotates in a right-handed sense, until the strike is N41 /sup 0/W at the 6.5 km level. (2) Magma chamber complex floor. The interval from 6.5 to 5.7 km, immediately over the primary conduit, is aseismic. This suggests differentially high fluid-to-rock ratios, and relatively weak pathways for further vertical transport into higher levels of the storage complex, as well as lateral leakage eastward into the Mauna Ulu staging area: for later vertical ascent beneath the upper east rift zone. Seismicity within the immediately subjacent rocks that form the top of the primary conduit (at 6.5 km) suggests that this inferred magma-rich horizon forms the effective floor of the summit storage complex. (3) Magma chamber crown. Intense seismicity over the 1.1--1.9 km depth interval defines an elliptical region in plan view.
Cadmium block of squid calcium currents. Macroscopic data and a kinetic model
1991-01-01
The mechanism of Cd2+ block of Ca2+ currents (ICa) was explored in squid neurons using whole-cell patch clamp. Control currents activated sigmoidally, more rapidly at more positive potentials, and did not inactivate significantly. External Cd2+ up to 250 microM reduced ICa reversibly. For small depolarizations, the current for a step of 10 ms increased to a maintained value, resembling the control; but for Vm greater than 0 mV, the increase was followed by a decrease, as Cd2+ block became greater. Final block was greater for larger depolarizations. At 0 mV the half-blocking concentration was 125 microM. Tail currents, measured as channels close, had an initial "hook" when recorded in Cd2+: currents increased transiently, then decreased. This suggests that Cd2+ escapes from some channels, which then conduct briefly before closing. Analysis of tail currents shows that Cd2+ does not slow channel closing. The data can be explained if Cd2+ is a permeant blocker of Ca2+ channels and if channels can close when occupied by Cd2+. Cd2+ permeates the channels, but binds transiently to a site in the pore, obstructing the passage of other ions (e.g., Ca2+). Dwell time depends on the transmembrane potential, becoming shorter for more negative internal potentials. A five-state model was used to simulate the steady-state and kinetic features. It combines a Hodgkin-Huxley type m2 gating scheme and a one-site Woodhull ionic blockage model for a permeant blocker and includes a closed blocked state. To fit the data, the binding site for Cd2+ had to be near the outer end of the pore, with a well depth of -12.2 RT, and with a barrier at each end of the pore. The model predicts that the Cd2+ entry rate is nearly voltage independent, but the exit rate is steeply voltage dependent (e-fold/17 mV). Analysis further suggests that the channel closes at a normal rate with Cd2+ in the pore. PMID:1660061
Nuclear physics: Macroscopic aspects
Swiatecki, W.J.
1993-12-01
A systematic macroscopic, leptodermous approach to nuclear statics and dynamics is described, based formally on the assumptions {h_bar} {yields} 0 and b/R << 1, where b is the surface diffuseness and R the nuclear radius. The resulting static model of shell-corrected nuclear binding energies and deformabilities is accurate to better than 1 part in a thousand and yields a firm determination of the principal properties of the nuclear fluid. As regards dynamics, the above approach suggests that nuclear shape evolutions will often be dominated by dissipation, but quantitative comparisons with experimental data are more difficult than in the case of statics. In its simplest liquid drop version the model exhibits interesting formal connections to the classic astronomical problem of rotating gravitating masses.
NASA Astrophysics Data System (ADS)
Qiu, Haixia; Kim, Michele M.; Penjweini, Rozhin; Zhu, Timothy C.
2016-08-01
Although photodynamic therapy (PDT) is an established modality for cancer treatment, current dosimetric quantities, such as light fluence and PDT dose, do not account for the differences in PDT oxygen consumption for different fluence rates (φ). A macroscopic model was adopted to evaluate using calculated reacted singlet oxygen concentration ([) to predict Photofrin-PDT outcome in mice bearing radiation-induced fibrosarcoma tumors, as singlet oxygen is the primary cytotoxic species responsible for cell death in type II PDT. Using a combination of fluences (50, 135, 200, and 250 J/cm2) and φ (50, 75, and 150 mW/cm2), tumor regrowth rate, k, was determined for each condition. A tumor cure index, CI=1-k/k, was calculated based on the k between PDT-treated groups and that of the control, k. The measured Photofrin concentration and light dose for each mouse were used to calculate PDT dose and [, while mean optical properties (μa=0.9 cm-1, μs‧=8.4 cm-1) were used to calculate φ for all mice. CI was correlated to the fluence, PDT dose, and [ with R2=0.35, 0.79, and 0.93, respectively. These results suggest that [ serves as a better dosimetric quantity for predicting PDT outcome.
Kumar, Milan; Edwards, Brian J; Paddison, Stephen J
2013-02-14
The membrane-ionomer interface is the critical interlink of the electrodes and catalyst to the polymer electrolyte membrane (PEM); together forming the membrane electrode assembly in current state-of-the-art PEM fuel cells. In this paper, proton conduction through the interface is investigated to understand its effect on the performance of a PEM fuel cell. The water containing domains at this interface were modeled as cylindrical pores/channels with the anionic groups (i.e., -SO(3)(-)) assumed to be fixed on the pore wall. The interactions of each species with all other species and an applied external field were examined. Molecular-based interaction potential energies were computed in a small test element of the pore and were scaled up in terms of macroscopic variables. Evolution equations of the density and momentum of the species (water molecules and hydronium ions) were derived within a framework of nonequilibrium thermodynamics. The resulting evolution equations for the species were solved analytically using an order-of-magnitude analysis to obtain an expression for the proton conductivity. Results show that the conductivity increases with increasing water content and pore radius, and strongly depends on the separation distance between the sulfonate groups and their distribution on the pore wall. It was also determined that the conductivity of two similar pores of different radii in series is limited by the pore with the smaller radius.
Ryabov, E.G.; Adeev, G.D.
2005-09-01
A macroscopic temperature-dependent model that takes into account nuclear forces of finite range is used to calculate the static and statistical properties of hot rotating compound nuclei. The level-density parameter is approximated by an expression of the leptodermous type. The resulting expansion coefficients are in good agreement with their counterparts proposed previously by A.V. Ignatyuk and his colleagues. The effect of taking simultaneously into account the temperature of a nucleus and its angular momentum on the quantities under study, such as the heights and positions of fission barriers and the effective moments of inertia of nuclei at the barrier, is considered, and the importance of doing this is demonstrated. The fissility parameter (Z{sup 2}/A){sub crit} and the position of the Businaro-Gallone point are studied versus temperature. It is found that, with increasing temperature, both parameters are shifted to the region of lighter nuclei. It is shown that the inclusion of temperature leads to qualitatively the same effects as the inclusion of the angular momentum of a nucleus, but, quantitatively, thermal excitation leads to smaller effects than rotational excitation.
NASA Astrophysics Data System (ADS)
Kumar, Milan; Edwards, Brian J.; Paddison, Stephen J.
2013-02-01
The membrane-ionomer interface is the critical interlink of the electrodes and catalyst to the polymer electrolyte membrane (PEM); together forming the membrane electrode assembly in current state-of-the-art PEM fuel cells. In this paper, proton conduction through the interface is investigated to understand its effect on the performance of a PEM fuel cell. The water containing domains at this interface were modeled as cylindrical pores/channels with the anionic groups (i.e., -SO3-) assumed to be fixed on the pore wall. The interactions of each species with all other species and an applied external field were examined. Molecular-based interaction potential energies were computed in a small test element of the pore and were scaled up in terms of macroscopic variables. Evolution equations of the density and momentum of the species (water molecules and hydronium ions) were derived within a framework of nonequilibrium thermodynamics. The resulting evolution equations for the species were solved analytically using an order-of-magnitude analysis to obtain an expression for the proton conductivity. Results show that the conductivity increases with increasing water content and pore radius, and strongly depends on the separation distance between the sulfonate groups and their distribution on the pore wall. It was also determined that the conductivity of two similar pores of different radii in series is limited by the pore with the smaller radius.
The macroscopic pancake bounce
NASA Astrophysics Data System (ADS)
Andersen Bro, Jonas; Sternberg Brogaard Jensen, Kasper; Nygaard Larsen, Alex; Yeomans, Julia M.; Hecksher, Tina
2017-01-01
We demonstrate that the so-called pancake bounce of millimetric water droplets on surfaces patterned with hydrophobic posts (Liu et al 2014 Nat. Phys. 10 515) can be reproduced on larger scales. In our experiment, a bed of nails plays the role of the structured surface and a water balloon models the water droplet. The macroscopic version largely reproduces the features of the microscopic experiment, including the Weber number dependence and the reduced contact time for pancake bouncing. The scalability of the experiment confirms the mechanisms of pancake bouncing, and allows us to measure the force exerted on the surface during the bounce. The experiment is simple and inexpensive and is an example where front-line research is accessible to student projects.
NASA Astrophysics Data System (ADS)
Li, Xianglin; Huang, Jing; Faghri, Amir
2016-11-01
A comprehensive review of the state-of-the-art macroscopic modeling studies on lithium oxygen (Li O2) and lithium air (Li-air) batteries has been presented. The Li O2 battery is a promising device for energy storage in portable electronics and electric vehicles due to its high specific energy. A number of technical challenges need to be addressed in order to bring this technology from laboratory concept to real products. The multi-scale, multi-physics phenomena in a Li O2 battery encompasses a wide range of scientific disciplines, including electrochemistry, heat and mass transfer, and material science. Modeling study provides a powerful tool to understand the charge-species transport phenomena inside a battery that cannot be captured by experimentation. It offers insight to optimize battery design and fabrication. Macroscopic models that treat battery components as continuous media will be the focus of this review while pore-scale sub-models that are integrated with macroscopic models to describe structural changes of battery components (mainly electrodes) will be presented and compared as well. Recent developments and opportunities for future improvement and advancement are also discussed. Finally, a detailed summary of property data relevant to Li O2 batteries is provided because of their critical role in modeling studies.
NASA Astrophysics Data System (ADS)
Chen, Chao; Ni, Peiyuan; Jonsson, Lage Tord Ingemar; Tilliander, Anders; Cheng, Guoguang; Jönsson, Pär Göran
2016-06-01
This paper presents computational fluid dynamics (CFD) simulation results of inclusions macroscopic transport as well as dynamic removal in tundishes. A novel treatment was implemented using the deposition velocity calculated by a revised unified Eulerian deposition model to replace the widely used Stokes rising velocity in the boundary conditions for inclusions removal at the steel-slag interface in tundishes. In this study, the dynamic removal for different size groups of inclusions at different steel-slag interfaces (smooth or rough) with different absorption conditions at the interface (partially or fully absorbed) in two tundish designs was studied. The results showed that the dynamic removal ratios were higher for larger inclusions than for smaller inclusions. Besides, the dynamic removal ratio was higher for rough interfaces than for smooth interfaces. On the other hand, regarding the cases when inclusions are partially or fully absorbed at a smooth steel-slag interface, the removal ratio values are proportional to the absorption proportion of inclusions at the steel-slag interface. Furthermore, the removal of inclusions in two tundish designs, i.e., with and without a weir and a dam were compared. Specifically, the tundish with a weir and a dam exhibited a better performance with respect to the removal of bigger inclusions (radii of 5, 7, and 9 μm) than that of the case without weir and dam. That was found to be due to the strong paralleling flow near the middle part of the top surface. However, the tundish without weir and dam showed a higher removal ratio of smaller inclusions (radius of 1 μm). The reason could be the presence of a paralleling flow near the inlet zone, where the inclusions deposition velocities were much higher than in other parts.
Kalin, Robert M
2004-06-01
Permeable reactive barriers are a technology that is one decade old, with most full-scale applications based on abiotic mechanisms. Though there is extensive literature on engineered bioreactors, natural biodegradation potential, and in situ remediation, it is only recently that engineered passive bioreactive barrier technology is being considered at the commercial scale to manage contaminated soil and groundwater risks. Recent full-scale studies are providing the scientific confidence in our understanding of coupled microbial (and genetic), hydrogeologic, and geochemical processes in this approach and have highlighted the need to further integrate engineering and science tools.
NASA Astrophysics Data System (ADS)
Chialvo, A. A.; Vlcek, L.; Cole, D. R.
2013-12-01
We address key issues regarding the behavior at CO2 environments under extreme silica confinement, which become of high relevance to the understanding of the process of geological storage of CO2, including (a) how the nature of the surface affects the mineral-fluid interfacial structure and the thermodynamic response functions (b) how the overlapping of mineral-fluid interfaces affects the partition of species between confinement and bulk, (c) how CO2 contaminants compete for preferential adsorption and affect the composition of the interfacial layers, and (d) how the presence of mineral stress might alter the interfacial/confinement phenomena. The effort comprises extensive isobaric-isothermal/grand-canonical molecular dynamics simulations of CO2 + contaminant systems based on optimized force-field parameterization 1-2. Based on this study we illustrate how the interplay between different types of fluid-surface interactions and extreme fluid confinement, i.e., strong overlapping of interfacial structures, can induce unexpected behavior such as (i) the significant reduction of the isothermal compressibility and isobaric thermal expansivity of confined CO2-rich phases relative to the corresponding bulk counterparts 2, (ii) drying out of the pore environment whose immediate consequence is a significant enhancement of the pore CO2 concentration relative to that of the corresponding bulk environment 3, and (iii) the significant effect of surface and fluid polarity on determining the preferential adsorption and resulting species partition. Finally, we discuss some macroscopic implications of our findings, including a novel route to define the mean density of confined fluids without requiring the estimation of the confined volume, and the inadequacy of temperature/average-density corresponding state modeling for the description of the behavior of confined fluids 3. (1) Vlcek, L.; Chialvo, A. A.; Cole, D. R. JCP B 2011, 115, 8775. (2) Chialvo, A. A.; Vlcek, L.; Cole, D. R
Freidman, Benjamin L; Terry, Deborah; Wilkins, Dan; Spedding, Tim; Gras, Sally L; Snape, Ian; Stevens, Geoffrey W; Mumford, Kathryn A
2017-05-01
A reliance on diesel generated power and a history of imperfect fuel management have created a legacy of petroleum hydrocarbon contamination at subantarctic Macquarie Island. Increasing environmental awareness and advances in contaminant characterisation and remediation technology have fostered an impetus to reduce the environmental risk associated with legacy sites. A funnel and gate permeable bio-reactive barrier (PRB) was installed in 2014 to address the migration of Special Antarctic Blend diesel from a spill that occurred in 2002, as well as older spills and residual contaminants in the soil at the Main Power House. The PRB gate comprised of granular activated carbon and natural clinoptilolite zeolite. Petroleum hydrocarbons migrating in the soil water were successfully captured on the reactive materials, with concentrations at the outflow of the barrier recorded as being below reporting limits. The nutrient and iron concentrations delivered to the barrier demonstrated high temporal variability with significant iron precipitation observed across the bed. The surface of the granular activated carbon was largely free from cell attachment while natural zeolite demonstrated patchy biofilm formation after 15 months following PRB installation. This study illustrates the importance of informed material selection at field scale to ensure that adsorption and biodegradation processes are utilised to manage the environmental risk associated with petroleum hydrocarbon spills. This study reports the first installation of a permeable bio-reactive barrier in the subantarctic.
Rank distributions: A panoramic macroscopic outlook
NASA Astrophysics Data System (ADS)
Eliazar, Iddo I.; Cohen, Morrel H.
2014-01-01
This paper presents a panoramic macroscopic outlook of rank distributions. We establish a general framework for the analysis of rank distributions, which classifies them into five macroscopic "socioeconomic" states: monarchy, oligarchy-feudalism, criticality, socialism-capitalism, and communism. Oligarchy-feudalism is shown to be characterized by discrete macroscopic rank distributions, and socialism-capitalism is shown to be characterized by continuous macroscopic size distributions. Criticality is a transition state between oligarchy-feudalism and socialism-capitalism, which can manifest allometric scaling with multifractal spectra. Monarchy and communism are extreme forms of oligarchy-feudalism and socialism-capitalism, respectively, in which the intrinsic randomness vanishes. The general framework is applied to three different models of rank distributions—top-down, bottom-up, and global—and unveils each model's macroscopic universality and versatility. The global model yields a macroscopic classification of the generalized Zipf law, an omnipresent form of rank distributions observed across the sciences. An amalgamation of the three models establishes a universal rank-distribution explanation for the macroscopic emergence of a prevalent class of continuous size distributions, ones governed by unimodal densities with both Pareto and inverse-Pareto power-law tails.
Rank distributions: a panoramic macroscopic outlook.
Eliazar, Iddo I; Cohen, Morrel H
2014-01-01
This paper presents a panoramic macroscopic outlook of rank distributions. We establish a general framework for the analysis of rank distributions, which classifies them into five macroscopic "socioeconomic" states: monarchy, oligarchy-feudalism, criticality, socialism-capitalism, and communism. Oligarchy-feudalism is shown to be characterized by discrete macroscopic rank distributions, and socialism-capitalism is shown to be characterized by continuous macroscopic size distributions. Criticality is a transition state between oligarchy-feudalism and socialism-capitalism, which can manifest allometric scaling with multifractal spectra. Monarchy and communism are extreme forms of oligarchy-feudalism and socialism-capitalism, respectively, in which the intrinsic randomness vanishes. The general framework is applied to three different models of rank distributions-top-down, bottom-up, and global-and unveils each model's macroscopic universality and versatility. The global model yields a macroscopic classification of the generalized Zipf law, an omnipresent form of rank distributions observed across the sciences. An amalgamation of the three models establishes a universal rank-distribution explanation for the macroscopic emergence of a prevalent class of continuous size distributions, ones governed by unimodal densities with both Pareto and inverse-Pareto power-law tails.
Microfabricated Valveless Devices for Thermal Bioreactions based on Diffusion-limited Evaporation
Wang, Fang; Yang, Ming; Burns, Mark A.
2009-01-01
Microfluidic devices that reduce evaporative loss during thermal bioreactions such as PCR without microvalves have been developed by relying on the principle of diffusion-limited evaporation. Both theoretical and experimental results demonstrate that the sample evaporative loss can be reduced by more than 20 times using long narrow diffusion channels on both sides of the reaction region. In order to further suppress the evaporation, the driving force for liquid evaporation is reduced by two additional techniques: decreasing the interfacial temperature using thermal isolation and reducing the vapor concentration gradient by replenishing water vapor in the diffusion channels. Both thermal isolation and vapor replenishment techniques can limit the sample evaporative loss to approximately 1% of the reaction content. PMID:18094766
Salinization alters fluxes of bioreactive elements from stream ecosystems across land use
NASA Astrophysics Data System (ADS)
Duan, S.; Kaushal, S. S.
2015-12-01
There has been increased salinization of fresh water over decades due to the use of road salt deicers, wastewater discharges, saltwater intrusion, human-accelerated weathering, and groundwater irrigation. Salinization can mobilize bioreactive elements (carbon, nitrogen, phosphorus, sulfur) chemically via ion exchange and/or biologically via influencing of microbial activity. However, the effects of salinization on coupled biogeochemical cycles are still not well understood. We investigated potential impacts of increased salinization on fluxes of bioreactive elements from stream ecosystems (sediments and riparian soils) to overlying stream water and evaluated the implications of percent urban land use on salinization effects. Two-day incubations of sediments and soils with stream and deionized water across three salt levels were conducted at eight routine monitoring stations across a land-use gradient at the Baltimore Ecosystem Study Long-Term Ecological Research (LTER) site in the Chesapeake Bay watershed. Results indicated (1) salinization typically increased sediment releases of labile dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), total dissolved Kjeldahl nitrogen (TKN) (ammonium + ammonia + dissolved organic nitrogen), and sediment transformations of nitrate; (2) salinization generally decreased DOC aromaticity and fluxes of soluble reactive phosphorus from both sediments and soils; (3) the effects of increased salinization on sediment releases of DOC and TKN and DOC quality increased with percentage watershed urbanization. Biogeochemical responses to salinization varied between sediments and riparian soils in releases of DOC and DIC, and nitrate transformations. The differential responses of riparian soils and sediments to increased salinization were likely due to differences in organic matter sources and composition. Our results suggest that short-term increases in salinization can cause releases of significant amounts of labile organic
NASA Astrophysics Data System (ADS)
García-Salaberri, Pablo A.; Gostick, Jeff T.; Hwang, Gisuk; Weber, Adam Z.; Vera, Marcos
2015-11-01
Macroscopic continuum models are an essential tool to understand the complex transport phenomena that take place in gas diffusion layers (GDLs) used in polymer electrolyte fuel cells (PEFCs). Previous work has shown that macroscopic models require effective properties obtained under uniform saturation conditions to get a consistent physical formulation. This issue, mostly unappreciated in the open literature, is addressed in detail in this work. To this end, lattice Boltzmann simulations were performed on tomographic images of dry and water-invaded carbon-paper GDL subsamples with nearly uniform porosity and saturation distributions. The computed effective diffusivity shows an anisotropic dependence on local porosity similar to that reported for morphologically analogous GDLs. In contrast, the dependence on local saturation is rather isotropic, following a nearly quadratic power law. The capability of the local correlations to recover the layer-scale properties obtained from inhomogeneous GDLs is checked by global averaging. Good agreement is found between the upscaled results and the diffusivity data of the GDL from which the present subsamples were taken, as well as other global data presented in the literature. A higher blockage effect of local saturation is, however, expected for the under-the-rib region in operating PEFCs.
NASA Astrophysics Data System (ADS)
Reitz, Meredith; Stark, Colin; Hung, Chi-Yao; Smith, Breannan; Grinspin, Eitan; Capart, Herve; Li, Liming; Crone, Timothy; Hsu, Leslie; Ling, Hoe
2014-05-01
characterize both the convergence of these grain-scale parameters toward the empirical coefficients of the macroscopic descriptions, and the deviations from continuum model predictions caused by nonlocal granular effects for quantities such as erosion rate. We will also summarize the context and implications of our work for both granular physics theory and granular flow hazard risk assessment.
Micciché, Maurizio; Arzt, Eduard; Kroner, Elmar
2014-05-28
The goal of our study is to better understand the design parameters of bioinspired dry adhesives inspired by geckos. For this, we fabricated single macroscopic pillars of 400 μm diameter with different aspect ratios and different tip shapes (i.e., flat tips, spherical tips with different radii, and mushroom tips with different diameters). Tilt-angle-dependent adhesion measurements showed that although the tip shape of the pillars strongly influences the pull-off force, the pull-off strength is similar for flat and mushroom-shaped tips. We found no tilt-angle dependency of adhesion for spherical tip structures and, except for high tilt angle and low preload experiments, no tilt-angle effect for mushroom-tip pillars. For flat-tip pillars, we found a strong influence of tilt angle on adhesion, which decreased linearly with increasing aspect ratio. The experiments show that for the tested aspect ratios between 1 and 5, a linear decrease of tilt-angle dependency is found. The results of our studies will help to design bioinspired adhesives for application on smooth and rough surfaces.
Makrodimitri, Zoi A; Unruh, Dominik J M; Economou, Ioannis G
2012-03-28
The self-diffusion coefficient of hydrogen (H(2)), carbon monoxide (CO) and water (H(2)O) in n-alkanes was studied by molecular dynamics simulation. Diffusion in a few pure n-alkanes (namely n-C(8), n-C(20), n-C(64) and n-C(96)) was examined. In addition, binary n-C(12)-n-C(96) mixtures with various compositions as well as more realistic five- and six-n-alkane component mixtures were simulated. In all cases, the TraPPE united atom force field was used for the n-alkane molecules. The force field for the mixture of n-alkanes was initially validated against experimental density values and was shown to be accurate. Moreover, macroscopic correlations for predicting diffusion coefficient of H(2), CO and H(2)O in n-alkanes and mixtures of n-alkanes were developed. The functional form of the correlation was based on the rough hard sphere theory (RHS). The correlation was applied to simulation data and an absolute average deviation (AAD) of 5.8% for pure n-alkanes and 3.4% for n-alkane mixtures was obtained. Correlation parameters vary in a systematic way with carbon number and so they can be used to provide predictions in the absence of any experimental or molecular simulation data. Finally, in order to reduce the number of adjustable parameters, for the n-alkane mixtures the "pseudo-carbon number" approach was used. This approach resulted in relatively higher deviation from MD simulation data (AAD of 18.2%); however, it provides a convenient and fast method to predict diffusion coefficients. The correlations developed here are expected to be useful for engineering calculations related to the design of the Gas-to-Liquid process.
NASA Astrophysics Data System (ADS)
Sleighter, Rachel L.; Cory, Rose M.; Kaplan, Louis A.; Abdulla, Hussain A. N.; Hatcher, Patrick G.
2014-08-01
The bioreactivity or susceptibility of dissolved organic matter (DOM) to microbial degradation in streams and rivers is of critical importance to global change studies, but a comprehensive understanding of DOM bioreactivity has been elusive due, in part, to the stunningly diverse assemblages of organic molecules within DOM. We approach this problem by employing a range of techniques to characterize DOM as it flows through biofilm reactors: dissolved organic carbon (DOC) concentrations, excitation emission matrix spectroscopy (EEMs), and ultrahigh resolution mass spectrometry. The EEMs and mass spectral data were analyzed using a combination of multivariate statistical approaches. We found that 45% of stream water DOC was biodegraded by microorganisms, including 31-45% of the humic DOC. This bioreactive DOM separated into two different groups: (1) H/C centered at 1.5 with O/C 0.1-0.5 or (2) low H/C of 0.5-1.0 spanning O/C 0.2-0.7 that were positively correlated (Spearman ranking) with chromophoric and fluorescent DOM (CDOM and FDOM, respectively). DOM that was more recalcitrant and resistant to microbial degradation aligned tightly in the center of the van Krevelen space (H/C 1.0-1.5, O/C 0.25-0.6) and negatively correlated (Spearman ranking) with CDOM and FDOM. These findings were supported further by principal component analysis and 2-D correlation analysis of the relative magnitudes of the mass spectral peaks assigned to molecular formulas. This study demonstrates that our approach of processing stream water through bioreactors followed by EEMs and FTICR-MS analyses, in combination with multivariate statistical analysis, allows for precise, robust characterization of compound bioreactivity and associated molecular level composition.
Sarkar, Srijata; Zhang, Lin; Subramaniam, Prasad; Lee, Ki-Bum; Garfunkel, Eric; Strickland, Pamela A Ohman; Mainelis, Gediminas; Lioy, Paul J; Tetley, Teresa D; Chung, Kian Fan; Zhang, Junfeng; Ryan, Mary; Porter, Alex; Schwander, Stephan
2014-01-01
Acting as fuel combustion catalysts to increase fuel economy, cerium dioxide (ceria, CeO2) nanoparticles have been used in Europe as diesel fuel additives (Envirox™). We attempted to examine the effects of particles emitted from a diesel engine burning either diesel (diesel exhaust particles, DEP) or diesel doped with various concentrations of CeO2 (DEP-Env) on innate immune responses in THP-1 and primary human peripheral blood mononuclear cells (PBMC). Batches of DEP and DEP-Env were obtained on three separate occasions using identical collection and extraction protocols with the aim of determining the reproducibility of particles generated at different times. However, we observed significant differences in size and surface charge (zeta potential) of the DEP and DEP-Env across the three batches. We also observed that exposure of THP-1 cells and PBMC to identical concentrations of DEP and DEP-Env from the three batches resulted in statistically significant differences in bioreactivity as determined by IL-1β, TNF-α, IL-6, IFN-γ, and IL-12p40 mRNA (by qRT-PCR) and protein expression (by ELISPOT assays). Importantly, bioreactivity was noted in very tight ranges of DEP size (60 to 120 nm) and zeta potential (-37 to -41 mV). Thus, these physical properties of DEP and DEP-Env were found to be the primary determinants of the bioreactivity measured in this study. Our findings also point to the potential risk of over- or under- estimation of expected bioreactivity effects (and by inference of public health risks) from bulk DEP use without taking into account potential batch-to-batch variations in physical (and possibly chemical) properties.
Sarkar, Srijata; Zhang, Lin; Subramaniam, Prasad; Lee, Ki-Bum; Garfunkel, Eric; Strickland, Pamela A. Ohman.; Mainelis, Gediminas; Lioy, Paul J.; Tetley, Teresa D.; Chung, Kian Fan; Zhang, Junfeng; Ryan, Mary; Porter, Alex; Schwander, Stephan
2014-01-01
Acting as fuel combustion catalysts to increase fuel economy, cerium dioxide (ceria, CeO2) nanoparticles have been used in Europe as diesel fuel additives (Envirox™). We attempted to examine the effects of particles emitted from a diesel engine burning either diesel (diesel exhaust particles, DEP) or diesel doped with various concentrations of CeO2 (DEP-Env) on innate immune responses in THP-1 and primary human peripheral blood mononuclear cells (PBMC). Batches of DEP and DEP-Env were obtained on three separate occasions using identical collection and extraction protocols with the aim of determining the reproducibility of particles generated at different times. However, we observed significant differences in size and surface charge (zeta potential) of the DEP and DEP-Env across the three batches. We also observed that exposure of THP-1 cells and PBMC to identical concentrations of DEP and DEP-Env from the three batches resulted in statistically significant differences in bioreactivity as determined by IL-1β, TNF-α, IL-6, IFN-γ, and IL-12p40 mRNA (by qRT-PCR) and protein expression (by ELISPOT assays). Importantly, bioreactivity was noted in very tight ranges of DEP size (60 to 120 nm) and zeta potential (−37 to −41 mV). Thus, these physical properties of DEP and DEP-Env were found to be the primary determinants of the bioreactivity measured in this study. Our findings also point to the potential risk of over- or under- estimation of expected bioreactivity effects (and by inference of public health risks) from bulk DEP use without taking into account potential batch-to-batch variations in physical (and possibly chemical) properties. PMID:24825358
NASA Astrophysics Data System (ADS)
Goldberg, S. J.; Carlson, C. A.; Nelson, N. B.; Siegel, D. A.
2004-12-01
Oceanic dissolved organic carbon (DOC) demonstrates a broad range of bioreactivity with turnover rates ranging from seconds to millennia. While the majority of dissolved organic matter remains uncharacterized through current chemical analyses, the ratio of total hydrolyzable carbohydrate (TCHO) contribution to bulk DOC does provide insight into the bioreactivity of DOC (Cowie and Hedges, 1994). Here we present a high spatial resolution data set of TCHO, dissolved combined neutral sugars (DCNS) and the ratio of TCHO and DCNS to the bulk DOC pool over the surface 1000 m. The samples were collected during two meridional transects of the U.S. Repeat Hydrography Program conducted in the North Atlantic during the autumn of 2003. Vertically, the TCHO concentrations were highest in the surface 50 m and decreased over 1000 m. Meridionally, TCHO were most concentrated in subtropical and tropical latitude surface waters (15-19 μ M C) yet the ratio of TCHO:DOC in these waters decreased from 26% in the subtropical latitudes to < 21% in more permanently stratified regions. Such a trend indicates an overall decrease in the degree of bioreactivity of bulk DOC from 35° N to the south concomitant with increased stratification. Interestingly, the highest levels of bacterial productivity did not coincide with the regions of high TCHO:DOC. Because TCHO pool consists of hydrolyzed material that is both labile and recalcitrant in nature, use of the TCHO:DOC as an index bioreactivity reveals that the TCHO portion of the DOC pool is reactive on longer time scales than those used to support rapid and instantaneous heterotrophic bacterial production.
Chang, Qiang; Herbst, Eric
2014-06-01
We have designed an improved algorithm that enables us to simulate the chemistry of cold dense interstellar clouds with a full gas-grain reaction network. The chemistry is treated by a unified microscopic-macroscopic Monte Carlo approach that includes photon penetration and bulk diffusion. To determine the significance of these two processes, we simulate the chemistry with three different models. In Model 1, we use an exponential treatment to follow how photons penetrate and photodissociate ice species throughout the grain mantle. Moreover, the products of photodissociation are allowed to diffuse via bulk diffusion and react within the ice mantle. Model 2 is similar to Model 1 but with a slower bulk diffusion rate. A reference Model 0, which only allows photodissociation reactions to occur on the top two layers, is also simulated. Photodesorption is assumed to occur from the top two layers in all three models. We found that the abundances of major stable species in grain mantles do not differ much among these three models, and the results of our simulation for the abundances of these species agree well with observations. Likewise, the abundances of gas-phase species in the three models do not vary. However, the abundances of radicals in grain mantles can differ by up to two orders of magnitude depending upon the degree of photon penetration and the bulk diffusion of photodissociation products. We also found that complex molecules can be formed at temperatures as low as 10 K in all three models.
NASA Astrophysics Data System (ADS)
Asimow, P. D.; Thomas, C.; Wolf, A. S.
2012-12-01
Silicate melts are the essential agents of planetary differentiation and evolution. Their phase relations, element partitioning preferences, density, and transport properties determine the fates of heat and mass flow in the high-temperature interior of active planets. In the early Earth and in extrasolar super-Earth-mass terrestrial planets it is these properties at very high pressure (> 100 GPa) that control the evolution from possible magma oceans to solid-state convecting mantles. Yet these melts are complex, dynamic materials that present many challenges to experimental, theoretical, and computational understanding or prediction of their properties. There has been encouraging convergence among various approaches to understanding the structure and dynamics of silicate melts at multiple scales: nearest- and next-nearest neighbor structural information is derived from spectroscopic techniques such as high-resolution multinuclear NMR; first-principles molecular dynamics probe structure and dynamics at scales up to hundreds of atoms; Archimedean, ultrasonic, sink/float, and shock wave methods probe macroscopic properties (and occasionally dynamics); and deformation and diffusion experiments probe dynamics at macroscopic scale and various time scales. One challenge that remains to integrating all this information is a predictive model of silicate liquid structure that agrees with experiments and simulation both at microscopic and macroscopic scale. In addition to our efforts to collect macroscopic equation of state data using shock wave methods across ever-wider ranges of temperature, pressure, and composition space, we have introduced a simple model of coordination statistics around cations that can form the basis of a conceptual and predictive link across scales and methods. This idea is explored in this presentation specifically with regard to the temperature dependence of sound speed in ultramafic liquids. This is a highly uncertain quantity and yet it is key, in
NASA Astrophysics Data System (ADS)
Menn, Scott A.; Hall, Hugh E.
1995-02-01
The integrated thermal neutron flux method of determining the macroscopic thermal neutron absorption cross-section of samples consisting of approx. 400 kg of unconsolidated geologic material, saturated with fresh water, to be used in borehole models is reported. One advantage of this method is that bulk cross-section determinations are made relative to a single standard, with fresh (distilled) water being used as the standard in this work. The values of matrix Σ determined for unconsolidated sand, limestone, and dolomite for the particular samples measured fall within the range of previously reported measurements of similar type samples. The method was checked using 50,000 ppm NaCl for which a value of 39.1 ± 0.5 c.u. was determined.
Macroscopic anisotropy in AA5019A sheets
Choi, S.H.; Brem, J.C.; Barlat, F.; Oh, K.H.
2000-05-11
The macroscopic anisotropy for typical texture components in aluminum alloys and AA5019A sheet samples (H48 and O temper conditions) were investigated. In order to simultaneously consider the effects of morphological texture and crystallographic texture on macroscopic anisotropy, predictions of plastic properties were carried out using a full-constraints Taylor model and a visco-plastic self-consistent (VPSC) polycrystal model. The yield stress and r-value (width-to-thickness plastic strain ratio in uniaxial tension) anisotropy predicted using the VPSC model were in good agreement with experimental data.
Macroscopic dynamics of cancer growth
NASA Astrophysics Data System (ADS)
Menchón, S. A.; Condat, C. A.
2007-04-01
Macroscopic modeling is used to describe various aspects of cancer growth. A recently proposed “dysnamical exponent” hypothesis is critically examined in the context of the angiogenic development. It is also shown that the emergence of necroses facilitates the growth of avascular tumors; the model yields an excellent fit to available experimental data, allowing for the determination of growth parameters. Finally, the global effects of an applied antitumoral immunotherapy are investigated. It is shown that, in the long run, the application of a therapeutical course leads to bigger tumors by weakening the intraspecific competition between surviving viable cancer cells. The strength of this model lies in its simplicity and in the amount of information that can be gleaned using only very general ideas.
Chemical composition and bioreactivity of PM2.5 during 2013 haze events in China
NASA Astrophysics Data System (ADS)
Ho, Kin-Fai; Ho, Steven Sai Hang; Huang, Ru-Jin; Chuang, Hsiao-Chi; Cao, Jun-Ji; Han, Yongming; Lui, Ka-Hei; Ning, Zhi; Chuang, Kai-Jen; Cheng, Tsun-Jen; Lee, Shun-Cheng; Hu, Di; Wang, Bei; Zhang, Renjian
2016-02-01
Chemical composition and bioreactivity of PM2.5 samples collected from Beijing (BJ), Xi'an (XA), Xiamen (XM) and Hong Kong (HK) in China during haze events were characterized. PM2.5 mass concentrations in BJ, XA, XM and HK in the episodes were found to be 258 ± 100 μg m-3, 233 ± 52 μg m-3, 46 ± 9 μg m-3 and 48 ± 13 μg m-3, respectively. Significant increase of sulfate, nitrate and ammonium concentrations in northern cities were observed. High contributions of biomass burning emissions to organic carbon (OC) in northern cities were estimated in this study implying frequent biomass burning during the haze periods. The urea concentrations in PM2.5 were 1855 ± 755 ng m-3 (BJ), 1124 ± 243 ng m-3 (XA), 543 ± 104 ng m-3 (XM) and 363 ± 61 ng m-3 (HK) suggesting higher or close to upper limits compared to other regions in the world. Dose-dependent alterations in oxidative potential, IL-6, IFN-γ and TNF-α levels were also investigated. The oxidative potential levels are BJ > XM > XA > HK, whereas levels of IL-6, IFN-γ and TNF-α were BJ > XA > XM > HK. The sulfate, nitrate, ammonium, OC, urea and levoglucosan are associated with oxidative-inflammatory responses. These experimental results are crucial for the policymakers to implement cost-effective abatement strategies for improving air quality.
NASA Astrophysics Data System (ADS)
Yu, Chao; Kang, Guozheng; Kan, Qianhua
2017-01-01
A macroscopic based multi-mechanism constitutive model is constructed in the framework of irreversible thermodynamics to describe the degeneration of shape memory effect occurring in the thermo-mechanical cyclic deformation of NiTi shape memory alloys (SMAs). Three phases, austenite A, twinned martensite Mt and detwinned martensite Md , as well as the phase transitions occurring between each pair of phases (A→ M t , Mt→ A , A→ M d , Md→ A , and Mt→ M d) are considered in the proposed model. Meanwhile, two kinds of inelastic deformation mechanisms, martensite transformation-induced plasticity and reorientation-induced plasticity, are used to explain the degeneration of shape memory effects of NiTi SMAs. The evolution equations of internal variables are proposed by attributing the degeneration of shape memory effect to the interaction between the three phases (A, Mt , and Md) and plastic deformation. Finally, the capability of the proposed model is verified by comparing the predictions with the experimental results of NiTi SMAs. It is shown that the degeneration of shape memory effect and its dependence on the loading level can be reasonably described by the proposed model.
Local realism of macroscopic correlations.
Ramanathan, R; Paterek, T; Kay, A; Kurzyński, P; Kaszlikowski, D
2011-08-05
We identify conditions under which correlations resulting from quantum measurements performed on macroscopic systems (systems composed of a number of particles of the order of the Avogadro number) can be described by local realism. We argue that the emergence of local realism at the macroscopic level is caused by an interplay between the monogamous nature of quantum correlations and the fact that macroscopic measurements do not reveal properties of individual particles.
Local Realism of Macroscopic Correlations
NASA Astrophysics Data System (ADS)
Ramanathan, R.; Paterek, T.; Kay, A.; Kurzyński, P.; Kaszlikowski, D.
2011-08-01
We identify conditions under which correlations resulting from quantum measurements performed on macroscopic systems (systems composed of a number of particles of the order of the Avogadro number) can be described by local realism. We argue that the emergence of local realism at the macroscopic level is caused by an interplay between the monogamous nature of quantum correlations and the fact that macroscopic measurements do not reveal properties of individual particles.
NASA Astrophysics Data System (ADS)
Faizrahnemoon, Mahsa; Schlote, Arieh; Maggi, Lorenzo; Crisostomi, Emanuele; Shorten, Robert
2015-11-01
This paper describes a Markov-chain-based approach to modelling multi-modal transportation networks. An advantage of the model is the ability to accommodate complex dynamics and handle huge amounts of data. The transition matrix of the Markov chain is built and the model is validated using the data extracted from a traffic simulator. A realistic test-case using multi-modal data from the city of London is given to further support the ability of the proposed methodology to handle big quantities of data. Then, we use the Markov chain as a control tool to improve the overall efficiency of a transportation network, and some practical examples are described to illustrate the potentials of the approach.
Marcucci, Lorenzo; Washio, Takumi; Yanagida, Toshio
2016-09-01
Muscle contractions are generated by cyclical interactions of myosin heads with actin filaments to form the actomyosin complex. To simulate actomyosin complex stable states, mathematical models usually define an energy landscape with a corresponding number of wells. The jumps between these wells are defined through rate constants. Almost all previous models assign these wells an infinite sharpness by imposing a relatively simple expression for the detailed balance, i.e., the ratio of the rate constants depends exponentially on the sole myosin elastic energy. Physically, this assumption corresponds to neglecting thermal fluctuations in the actomyosin complex stable states. By comparing three mathematical models, we examine the extent to which this hypothesis affects muscle model predictions at the single cross-bridge, single fiber, and organ levels in a ceteris paribus analysis. We show that including fluctuations in stable states allows the lever arm of the myosin to easily and dynamically explore all possible minima in the energy landscape, generating several backward and forward jumps between states during the lifetime of the actomyosin complex, whereas the infinitely sharp minima case is characterized by fewer jumps between states. Moreover, the analysis predicts that thermal fluctuations enable a more efficient contraction mechanism, in which a higher force is sustained by fewer attached cross-bridges.
2016-01-01
Muscle contractions are generated by cyclical interactions of myosin heads with actin filaments to form the actomyosin complex. To simulate actomyosin complex stable states, mathematical models usually define an energy landscape with a corresponding number of wells. The jumps between these wells are defined through rate constants. Almost all previous models assign these wells an infinite sharpness by imposing a relatively simple expression for the detailed balance, i.e., the ratio of the rate constants depends exponentially on the sole myosin elastic energy. Physically, this assumption corresponds to neglecting thermal fluctuations in the actomyosin complex stable states. By comparing three mathematical models, we examine the extent to which this hypothesis affects muscle model predictions at the single cross-bridge, single fiber, and organ levels in a ceteris paribus analysis. We show that including fluctuations in stable states allows the lever arm of the myosin to easily and dynamically explore all possible minima in the energy landscape, generating several backward and forward jumps between states during the lifetime of the actomyosin complex, whereas the infinitely sharp minima case is characterized by fewer jumps between states. Moreover, the analysis predicts that thermal fluctuations enable a more efficient contraction mechanism, in which a higher force is sustained by fewer attached cross-bridges. PMID:27626630
Size-dependent tuning of horseradish peroxidase bioreactivity by gold nanoparticles
NASA Astrophysics Data System (ADS)
Wu, Haohao; Liu, Yi; Li, Meng; Chong, Yu; Zeng, Mingyong; Lo, Y. Martin; Yin, Jun-Jie
2015-02-01
Molecules with diverse biological functions, such as heme peroxidases, can be useful tools for identifying potential biological effects of gold nanoparticles (AuNPs) at the molecular level. Here, using UV-Vis, circular dichroism, dynamic light scattering, and electron spin resonance spectroscopy, we report tuning of horseradish peroxidase (HRP) bioactivity by reactant-free AuNPs with diameters of 5, 10, 15, 30 and 60 nm (Au-5 nm, Au-10 nm, Au-15 nm, Au-30 nm and Au-60 nm). HRP conjugation to AuNPs was observed with only Au-5 nm and Au-10 nm prominently increasing the α-helicity of the enzyme to extents inversely related to their size. Au-5 nm inhibited both HRP peroxidase activity toward 3,3',5,5'-tetramethylbenzidine and HRP compound I/II reactivity toward 5,5-dimethyl-1-pyrroline N-oxide. Au-5 nm enhanced the HRP peroxidase activity toward ascorbic acid and the HRP compound I/II reactivity toward redox-active residues in the HRP protein moiety. Further, Au-5 nm also decreased the catalase- and oxidase-like activities of HRP. Au-10 nm showed similar, but weaker effects, while Au-15 nm, Au-30 nm and Au-60 nm had no effect. Results suggest that AuNPs can size-dependently enhance or inhibit HRP bioreactivity toward substrates with different redox potentials via a mechanism involving extension of the HRP substrate access channel and decline in the redox potentials of HRP catalytic intermediates.Molecules with diverse biological functions, such as heme peroxidases, can be useful tools for identifying potential biological effects of gold nanoparticles (AuNPs) at the molecular level. Here, using UV-Vis, circular dichroism, dynamic light scattering, and electron spin resonance spectroscopy, we report tuning of horseradish peroxidase (HRP) bioactivity by reactant-free AuNPs with diameters of 5, 10, 15, 30 and 60 nm (Au-5 nm, Au-10 nm, Au-15 nm, Au-30 nm and Au-60 nm). HRP conjugation to AuNPs was observed with only Au-5 nm and Au-10 nm prominently increasing the
Himmelheber, David W.; Pennell, Kurt D.; Hughes, Joseph B.
2011-01-01
The development of bioreactive sediment caps, in which microorganisms capable of contaminant transformation are placed within an in situ cap, provides a potential remedial design that can sustainably treat sediment and groundwater contaminants. The goal of this study was to evaluate the ability and limitations of a mixed, anaerobic dechlorinating consortium to treat chlorinated ethenes within a sand-based cap. Results of batch experiments demonstrate that a tetrachloroethene (PCE)-to-ethene mixed consortium was able to completely dechlorinate dissolved-phase PCE to ethene when supplied only with sediment porewater obtained from a sediment column. To simulate a bioreactive cap, laboratory-scale sand columns inoculated with the mixed culture were placed in series with an upflow sediment column and directly supplied sediment effluent and dissolved-phase chlorinated ethenes. The mixed consortium was not able to sustain dechlorination activity at a retention time of 0.5 days without delivery of amendments to the sediment effluent, evidenced by the loss of cis-1,2-dichloroethene (cis-DCE) dechlorination to vinyl chloride. When soluble electron donor was supplied to the sediment effluent, complete dechlorination of cis-DCE to ethene was observed at retention times of 0.5 days, suggesting that sediment effluent lacked sufficient electron donor to maintain active dechlorination within the sediment cap. Introduction of elevated contaminant concentrations also limited biotransformation performance of the dechlorinating consortium within the cap. These findings indicate that in situ bioreactive capping can be a feasible remedial approach, provided that residence times are adequate and that appropriate levels of electron donor and contaminant exist within the cap. PMID:21872291
Himmelheber, David W; Pennell, Kurt D; Hughes, Joseph B
2011-11-01
The development of bioreactive sediment caps, in which microorganisms capable of contaminant transformation are placed within an in situ cap, provides a potential remedial design that can sustainably treat sediment and groundwater contaminants. The goal of this study was to evaluate the ability and limitations of a mixed, anaerobic dechlorinating consortium to treat chlorinated ethenes within a sand-based cap. Results of batch experiments demonstrate that a tetrachloroethene (PCE)-to-ethene mixed consortium was able to completely dechlorinate dissolved-phase PCE to ethene when supplied only with sediment porewater obtained from a sediment column. To simulate a bioreactive cap, laboratory-scale sand columns inoculated with the mixed culture were placed in series with an upflow sediment column and directly supplied sediment effluent and dissolved-phase chlorinated ethenes. The mixed consortium was not able to sustain dechlorination activity at a retention time of 0.5 days without delivery of amendments to the sediment effluent, evidenced by the loss of cis-1,2-dichloroethene (cis-DCE) dechlorination to vinyl chloride. When soluble electron donor was supplied to the sediment effluent, complete dechlorination of cis-DCE to ethene was observed at retention times of 0.5 days, suggesting that sediment effluent lacked sufficient electron donor to maintain active dechlorination within the sediment cap. Introduction of elevated contaminant concentrations also limited biotransformation performance of the dechlorinating consortium within the cap. These findings indicate that in situ bioreactive capping can be a feasible remedial approach, provided that residence times are adequate and that appropriate levels of electron donor and contaminant exist within the cap.
Parameswaran, Harikrishnan; Majumdar, Arnab; Suki, Béla
2011-04-01
Pulmonary emphysema is a connective tissue disease characterized by the progressive destruction of alveolar walls leading to airspace enlargement and decreased elastic recoil of the lung. However, the relationship between microscopic tissue structure and decline in stiffness of the lung is not well understood. In this study, we developed a 3D computational model of lung tissue in which a pre-strained cuboidal block of tissue was represented by a tessellation of space filling polyhedra, with each polyhedral unit-cell representing an alveolus. Destruction of alveolar walls was mimicked by eliminating faces that separate two polyhedral either randomly or in a spatially correlated manner, in which the highest force bearing walls were removed at each step. Simulations were carried out to establish a link between the geometries that emerged and the rate of decline in bulk modulus of the tissue block. The spatially correlated process set up by the force-based destruction lead to a significantly faster rate of decline in bulk modulus accompanied by highly heterogeneous structures than the random destruction pattern. Using the Karhunen-Loève transformation, an estimator of the change in bulk modulus from the first four moments of airspace cell volumes was setup. Simulations were then obtained for tissue destruction with different idealized alveolar geometry, levels of pre-strain, linear and nonlinear elasticity assumptions for alveolar walls and also mixed destruction patterns where both random and force-based destruction occurs simultaneously. In all these cases, the change in bulk modulus from cell volumes was accurately estimated. We conclude that microscopic structural changes in emphysema and the associated decline in tissue stiffness are linked by the spatial pattern of the destruction process.
NASA Technical Reports Server (NTRS)
Goldberg, Robert K.; Carney, Kelly S.; DuBois, Paul; Hoffarth, Canio; Rajan, Subramaniam; Blankenhorn, Gunther
2015-01-01
Several key capabilities have been identified by the aerospace community as lacking in the material/models for composite materials currently available within commercial transient dynamic finite element codes such as LS-DYNA. Some of the specific desired features that have been identified include the incorporation of both plasticity and damage within the material model, the capability of using the material model to analyze the response of both three-dimensional solid elements and two dimensional shell elements, and the ability to simulate the response of composites composed with a variety of composite architectures, including laminates, weaves and braids. In addition, a need has been expressed to have a material model that utilizes tabulated experimentally based input to define the evolution of plasticity and damage as opposed to utilizing discrete input parameters (such as modulus and strength) and analytical functions based on curve fitting. To begin to address these needs, an orthotropic macroscopic plasticity based model suitable for implementation within LS-DYNA has been developed. Specifically, the Tsai-Wu composite failure model has been generalized and extended to a strain-hardening based orthotropic plasticity model with a non-associative flow rule. The coefficients in the yield function are determined based on tabulated stress-strain curves in the various normal and shear directions, along with selected off-axis curves. Incorporating rate dependence into the yield function is achieved by using a series of tabluated input curves, each at a different constant strain rate. The non-associative flow-rule is used to compute the evolution of the effective plastic strain. Systematic procedures have been developed to determine the values of the various coefficients in the yield function and the flow rule based on the tabulated input data. An algorithm based on the radial return method has been developed to facilitate the numerical implementation of the material
The bioreactivity of the sub-10 μm component of volcanic ash: Soufrière Hills volcano, Montserrat.
Jones, Timothy; Bérubé, Kelly
2011-10-30
With the recent eruption of the Icelandic volcano Eyafallajökull and resulting ash cloud over much of Europe there was considerable concern about possible respiratory hazards. Volcanic ash can contain minerals that are known human respiratory health hazards such as cristobalite. Short-term ash exposures can cause skin sores, respiratory and ocular irritations and exacerbation of pre-existing lung conditions such as asthma. Long-term occupational level exposures to crystalline silicon dioxide can cause lung inflammation, oedema, fibrosis and cancer. The potential health effects would be dependent on factors including mineralogy, surface chemistry, size, and levels and duration of exposure. Bulk ash from the Soufrière Hills volcano was sourced and inhalable (<2.5 μm) ash samples prepared and physicochemically characterised. The fine ash samples were tested for bioreactivity by SDS-PAGE which determined the strength of binding between mineral grains and lung proteins. Selected proteins bound tightly to cristobalite, and bound loosely to other ash components. A positive correlation was seen between the amount of SiO(2) in the sample and the strength of the binding. The strength of binding is a function of the mineral's bioreactivity, and therefore, a potential geo-biomarker of respiratory risk.
Lluís Garcés, Josep; Rey-Castro, Carlos; David, Calin; Madurga, Sergio; Mas, Francesc; Pastor, Isabel; Puy, Jaume
2009-11-19
The binding of ions or other small molecules to macromolecules and surfaces can be macroscopically characterized by means of the stepwise (or stoichiometric) equilibrium constants, which can be obtained experimentally from coverage versus concentration data. The present work presents a novel, simple, and direct interpretation of the stepwise constants in terms of the microscopic, site-specific, stability constants. This formalism can be applied to the most general case, including the heterogeneity of the sites, interactions among them, multicomponent adsorption, and so forth, and, in particular, to chelate complexation. We show that the stepwise equilibrium constants can be expressed as a product of two factors, (i) the average number of free potential sites (per bound ion) of the microscopic species to be complexed (stoichiometric factor) and (ii) the average of the microscopic stability constants of their free potential sites. The latter factor generalizes the concept of the intrinsic equilibrium constant to systems with chelate complexation and reduces to the standard definition for monodentate binding. However, in the case of heterogeneous multidentate complexation, the stoichiometric factor cannot be known a priori, so that the finding of the intrinsic constants is not trivial. One option is to approximate the stoichiometric factor by the value that would correspond to identical active centers. We investigate the accuracy of this assumption by comparing the resulting approximate intrinsic constants to those obtained by Monte Carlo simulation of several binding models. For the cases investigated, it is found that the assumption is quite accurate when no correlated structures (typical of short-range interactions) are formed along the chain. For adsorption of particles attached to a large number of active centers, the formalism presented here leads to the Widom particle insertion method.
Percolation and hysteresis in macroscopic capillarity
NASA Astrophysics Data System (ADS)
Hilfer, Rudolf
2010-05-01
The concepts of relative permeability and capillary pressure are crucial for the accepted traditional theory of two phase flow in porous media. Recently a theoretical approach was introduced that does not require these concepts as input [1][2][3]. Instead it was based on the concept of hydraulic percolation of fluid phases. The presentation will describe this novel approach. It allows to simulate processes with simultaneous occurence of drainage and imbibition. Furthermore, it predicts residual saturations and their spatiotemporal changes during two phase immiscible displacement [1][2][3][4][5]. [1] R. Hilfer. Capillary Pressure, Hysteresis and Residual Saturation in Porous Media, Physica A, vol. 359, pp. 119, 2006. [2] R. Hilfer. Macroscopic Capillarity and Hysteresis for Flow in Porous Media, Physical Review E, vol. 73, pp. 016307, 2006. [3] R. Hilfer. Macroscopic capillarity without a constitutive capillary pressure function, Physica A, vol. 371, pp. 209, 2006. [4] R. Hilfer. Modeling and Simulation of Macrocapillarity, in: P. Garrido et al. (eds.) Modeling and Simulation of Materials vol. CP1091, pp. 141, American Institute of Physcis, New York, 2009. [5] R. Hilfer and F. Doster. Percolation as a basic concept for macroscopic capillarity, Transport in Porous Media, DOI 10.1007/s11242-009-9395-0, in print, 2009.
Macroscopic theory of dark sector
NASA Astrophysics Data System (ADS)
Meierovich, Boris
A simple Lagrangian with squared covariant divergence of a vector field as a kinetic term turned out an adequate tool for macroscopic description of the dark sector. The zero-mass field acts as the dark energy. Its energy-momentum tensor is a simple additive to the cosmological constant [1]. Space-like and time-like massive vector fields describe two different forms of dark matter. The space-like massive vector field is attractive. It is responsible for the observed plateau in galaxy rotation curves [2]. The time-like massive field displays repulsive elasticity. In balance with dark energy and ordinary matter it provides a four parametric diversity of regular solutions of the Einstein equations describing different possible cosmological and oscillating non-singular scenarios of evolution of the universe [3]. In particular, the singular big bang turns into a regular inflation-like transition from contraction to expansion with the accelerate expansion at late times. The fine-tuned Friedman-Robertson-Walker singular solution corresponds to the particular limiting case at the boundary of existence of regular oscillating solutions in the absence of vector fields. The simplicity of the general covariant expression for the energy-momentum tensor allows to analyse the main properties of the dark sector analytically and avoid unnecessary model assumptions. It opens a possibility to trace how the additional attraction of the space-like dark matter, dominating in the galaxy scale, transforms into the elastic repulsion of the time-like dark matter, dominating in the scale of the Universe. 1. B. E. Meierovich. "Vector fields in multidimensional cosmology". Phys. Rev. D 84, 064037 (2011). 2. B. E. Meierovich. "Galaxy rotation curves driven by massive vector fields: Key to the theory of the dark sector". Phys. Rev. D 87, 103510, (2013). 3. B. E. Meierovich. "Towards the theory of the evolution of the Universe". Phys. Rev. D 85, 123544 (2012).
Harnessing Macroscopic Forces in Catalysis
2009-11-09
that macroscopic deformation of an elastomeric support could result in molecular deformation of embedded, stress-bearing catalysts and influence their... elastomeric support could result in molecular deformation of embedded, stress-bearing catalysts and influence their reactivity. The focus was on the...a mechanocatalyst. Our Specific Aims were: Specific Aim 1. Synthesize elastomeric organogels and bulk rubbers with embedded, stress-bearing
Macroscopic quantum electrodynamics and duality.
Buhmann, Stefan Yoshi; Scheel, Stefan
2009-04-10
We discuss under what conditions the duality between electric and magnetic fields is a valid symmetry of macroscopic quantum electrodynamics. It is shown that Maxwell's equations in the absence of free charges satisfy duality invariance on an operator level, whereas this is not true for Lorentz forces and atom-field couplings in general. We prove that derived quantities such as Casimir forces, local-field corrected decay rates, as well as van der Waals potentials are invariant with respect to a global exchange of electric and magnetic quantities. This exact symmetry can be used to deduce the physics of new configurations on the basis of already established ones.
Macroscopic theory for capillary-pressure hysteresis.
Athukorallage, Bhagya; Aulisa, Eugenio; Iyer, Ram; Zhang, Larry
2015-03-03
In this article, we present a theory of macroscopic contact angle hysteresis by considering the minimization of the Helmholtz free energy of a solid-liquid-gas system over a convex set, subject to a constant volume constraint. The liquid and solid surfaces in contact are assumed to adhere weakly to each other, causing the interfacial energy to be set-valued. A simple calculus of variations argument for the minimization of the Helmholtz energy leads to the Young-Laplace equation for the drop surface in contact with the gas and a variational inequality that yields contact angle hysteresis for advancing/receding flow. We also show that the Young-Laplace equation with a Dirichlet boundary condition together with the variational inequality yields a basic hysteresis operator that describes the relationship between capillary pressure and volume. We validate the theory using results from the experiment for a sessile macroscopic drop. Although the capillary effect is a complex phenomenon even for a droplet as various points along the contact line might be pinned, the capillary pressure and volume of the drop are scalar variables that encapsulate the global quasistatic energy information for the entire droplet. Studying the capillary pressure versus volume relationship greatly simplifies the understanding and modeling of the phenomenon just as scalar magnetic hysteresis graphs greatly aided the modeling of devices with magnetic materials.
Measurement contextuality is implied by macroscopic realism
Chen Zeqian; Montina, A.
2011-04-15
Ontological theories of quantum mechanics provide a realistic description of single systems by means of well-defined quantities conditioning the measurement outcomes. In order to be complete, they should also fulfill the minimal condition of macroscopic realism. Under the assumption of outcome determinism and for Hilbert space dimension greater than 2, they were all proved to be contextual for projective measurements. In recent years a generalized concept of noncontextuality was introduced that applies also to the case of outcome indeterminism and unsharp measurements. It was pointed out that the Beltrametti-Bugajski model is an example of measurement noncontextual indeterminist theory. Here we provide a simple proof that this model is the only one with such a feature for projective measurements and Hilbert space dimension greater than 2. In other words, there is no extension of quantum theory providing more accurate predictions of outcomes and simultaneously preserving the minimal labeling of events through projective operators. As a corollary, noncontextuality for projective measurements implies noncontextuality for unsharp measurements. By noting that the condition of macroscopic realism requires an extension of quantum theory, unless a breaking of unitarity is invoked, we arrive at the conclusion that the only way to solve the measurement problem in the framework of an ontological theory is by relaxing the hypothesis of measurement noncontextuality in its generalized sense.
Assessing Macroscopic Evapotranspiration Function Response to Climate
NASA Astrophysics Data System (ADS)
Gharun, M.; Vervoort, R. W.; Turnbull, T.; Henry, J.; Adams, M.
2012-12-01
Evapotranspiration (ET) by forests can reach up to 100% of rainfall in Australia, and is a substantial component of the water balance. Transpiration is a major part of the ET and it is well-known that transpiration depends on a combination of physiological and environmental controls. As a consequence of well-ventilated canopies of eucalypt forests and close decoupling to the atmosphere, atmospheric conditions exert a large control over transpiration. We measured a suit of environmental variables including temperature, humidity, radiation, and soil moisture concurrently with transpiration in a range of eucalypt forests. We observed that atmospheric demand (VPD) exerts the strongest control over transpiration. Experimental evidence also showed a strong dependency of the control on soil moisture abundance in the top soil layer. In many eco-hydrological models actual ET is represented with a linear transformation of potential ET based on the soil moisture condition, a so-called macroscopic approach. Such ET functions lump various soil and plant factors, are not experimentally supported and therefore quite poorly validated. Different combinations of atmospheric demand and soil moisture availability lead to diverse behaviour of the macroscopic ET function. Based on our observations in this study, we propose a novel approach that improves portray of transpiration, evaporation, drainage and hence the loss of water from the root zone. We used a modified version of the Norwegian HBV model to test our approach over a medium size catchment (150 km2) in south east Australia.
Lui, K H; Bandowe, Benjamin A Musa; Ho, Steven Sai Hang; Chuang, Hsiao-Chi; Cao, Jun-Ji; Chuang, Kai-Jen; Lee, S C; Hu, Di; Ho, K F
2016-06-01
The chemical and bioreactivity properties of fine particulate matter (PM2.5) emitted during controlled burning of different brands of incense were characterized. Incenses marketed as being environmentally friendly emitted lower mass of PM2.5 particulates than did traditional incenses. However, the environmentally friendly incenses produced higher total concentrations of non-volatile polycyclic aromatic hydrocarbons (PAHs) and some oxygenated polycyclic aromatic hydrocarbons (OPAHs). Human alveolar epithelial A549 cells were exposed to the collected PM2.5, followed by determining oxidative stress and inflammation. There was moderate to strong positive correlation (R > 0.60, p < 0.05) between selected PAHs and OPAHs against oxidative-inflammatory responses. Strong positive correlation was observed between interleukin 6 (IL-6) and summation of total Group B2 PAHs/OPAHs (∑7PAHs/ΣOPAHs). The experimental data indicate that emissions from the environmentally friendly incenses contained higher concentrations of several PAH and OPAH compounds than did traditional incense. Moreover, these PAHs and OPAHs were strongly correlated with inflammatory responses. The findings suggest a need to revise existing regulation of such products.
Deterministic Creation of Macroscopic Cat States
Lombardo, Daniel; Twamley, Jason
2015-01-01
Despite current technological advances, observing quantum mechanical effects outside of the nanoscopic realm is extremely challenging. For this reason, the observation of such effects on larger scale systems is currently one of the most attractive goals in quantum science. Many experimental protocols have been proposed for both the creation and observation of quantum states on macroscopic scales, in particular, in the field of optomechanics. The majority of these proposals, however, rely on performing measurements, making them probabilistic. In this work we develop a completely deterministic method of macroscopic quantum state creation. We study the prototypical optomechanical Membrane In The Middle model and show that by controlling the membrane’s opacity, and through careful choice of the optical cavity initial state, we can deterministically create and grow the spatial extent of the membrane’s position into a large cat state. It is found that by using a Bose-Einstein condensate as a membrane high fidelity cat states with spatial separations of up to ∼300 nm can be achieved. PMID:26345157
Gonzalez Carter, Daniel A.; Motskin, Michael; Pienaar, Ilse S.; Chen, Shu; Hu, Sheng; Ruenraroengsak, Pakatip; Ryan, Mary P.; Shaffer, Milo S. P.; Dexter, David T.
2016-01-01
Multi-walled carbon nanotubes (MWNTs) are increasingly being developed both as neuro-therapeutic drug delivery systems to the brain and as neural scaffolds to drive tissue regeneration across lesion sites. MWNTs with different degrees of acid oxidation may have different bioreactivities and propensities to aggregate in the extracellular environment, and both individualised and aggregated MWNTs may be expected to be found in the brain. Before practical application, it is vital to understand how both aggregates and individual MWNTs will interact with local phagocytic immune cells, the microglia, and ultimately to determine their biopersistence in the brain. The processing of extra- and intracellular MWNTs (both pristine and when acid oxidised) by microglia was characterised across multiple length scales by correlating a range of dynamic, quantitative and multi-scale techniques, including: UV-vis spectroscopy, light microscopy, focussed ion beam scanning electron microscopy and transmission electron microscopy. Dynamic, live cell imaging revealed the ability of microglia to break apart and internalise micron-sized extracellular agglomerates of acid oxidised MWNT, but not pristine MWNTs. The total amount of MWNTs internalised by, or strongly bound to, microglia was quantified as a function of time. Neither the significant uptake of oxidised MWNTs, nor the incomplete uptake of pristine MWNTs affected microglial viability, pro-inflammatory cytokine release or nitric oxide production. However, after 24 hrs exposure to pristine MWNTs, a significant increase in the production of reactive oxygen species was observed. Small aggregates and individualised oxidised MWNTs were present in the cytoplasm and vesicles, including within multilaminar bodies, after 72 hours. Some evidence of morphological damage to oxidised MWNT structure was observed including highly disordered graphitic structures, suggesting possible biodegradation. This work demonstrates the utility of dynamic
Black holes and quantumness on macroscopic scales
NASA Astrophysics Data System (ADS)
Flassig, Daniel; Pritzel, Alexander; Wintergerst, Nico
2013-04-01
It has recently been suggested that black holes may be described as condensates of weakly interacting gravitons at a critical point, exhibiting strong quantum effects. In this paper, we study a model system of attractive bosons in one spatial dimension which is known to undergo a quantum phase transition. We demonstrate explicitly that indeed quantum effects are important at the critical point, even if the number of particles is macroscopic. Most prominently, we evaluate the entropy of entanglement between different momentum modes and observe it to become maximal at the critical point. Furthermore, we explicitly see that the leading entanglement is between long-wavelength modes and is hence a feature independent of ultraviolet physics. If applicable to black holes, our findings substantiate the conjectured breakdown of semiclassical physics even for large black holes. This can resolve long-standing mysteries, such as the information paradox and the no-hair theorem.
Graphene chiral liquid crystals and macroscopic assembled fibres
Xu, Zhen; Gao, Chao
2011-01-01
Chirality and liquid crystals are both widely expressed in nature and biology. Helical assembly of mesophasic molecules and colloids may produce intriguing chiral liquid crystals. To date, chiral liquid crystals of 2D colloids have not been explored. As a typical 2D colloid, graphene is now receiving unprecedented attention. However, making macroscopic graphene fibres is hindered by the poor dispersibility of graphene and by the lack of an assembly method. Here we report that soluble, chemically oxidized graphene or graphene oxide sheets can form chiral liquid crystals in a twist-grain-boundary phase-like model with simultaneous lamellar ordering and long-range helical frustrations. Aqueous graphene oxide liquid crystals were continuously spun into metres of macroscopic graphene oxide fibres; subsequent chemical reduction gave the first macroscopic neat graphene fibres with high conductivity and good mechanical performance. The flexible, strong graphene fibres were knitted into designed patterns and into directionally conductive textiles. PMID:22146390
Macroscopic analyses of communicability structures in complex networks
NASA Astrophysics Data System (ADS)
Min, Seungsik; Chang, Ki-Ho; Na, Sungjoon; Kim, Kyungsik
2016-11-01
We study the dynamical property of macroscopic community structures in two scientific societies. The type of data is extracted from author networks in both the Korean Meteorological Society and the Korean Physical Society. We discuss some notable methods for giving evolutionary information as the community structure is investigated using the model of oscillator networks. We simulate and analyze macroscopic community metrics such as the entropy, the natural connectivity, the free energy, the total energy, and the bipartivity in the community structures of the two scientific societies. We particularly compare and analyze the statistical values between the two scientific societies.
Macroscopic characterisations of Web accessibility
NASA Astrophysics Data System (ADS)
Lopes, Rui; Carriço, Luis
2010-12-01
The Web Science framework poses fundamental questions on the analysis of the Web, by focusing on how microscopic properties (e.g. at the level of a Web page or Web site) emerge into macroscopic properties and phenomena. One research topic on the analysis of the Web is Web accessibility evaluation, which centres on understanding how accessible a Web page is for people with disabilities. However, when framing Web accessibility evaluation on Web Science, we have found that existing research stays at the microscopic level. This article presents an experimental study on framing Web accessibility evaluation into Web Science's goals. This study resulted in novel accessibility properties of the Web not found at microscopic levels, as well as of Web accessibility evaluation processes themselves. We observed at large scale some of the empirical knowledge on how accessibility is perceived by designers and developers, such as the disparity of interpretations of accessibility evaluation tools warnings. We also found a direct relation between accessibility quality and Web page complexity. We provide a set of guidelines for designing Web pages, education on Web accessibility, as well as on the computational limits of large-scale Web accessibility evaluations.
Links between microscopic and macroscopic fluid mechanics
NASA Astrophysics Data System (ADS)
Hoover, Wm. G.; Hoover, C. G.
2003-01-01
The microscopic and macroscopic versions of fluid mechanics differ qualitatively. Microscopic particles obey time-reversible ordinary differential equations. The resulting particle trajectories {q(t)} may be time-averaged or ensemble-averaged so as to generate field quantities corresponding to macroscopic variables. On the other hand, the macroscopic continuum fields described by fluid mechanics follow irreversible partial differential equations. Smooth particle methods bridge the gap separating these two views of fluids by solving the macroscopic field equations with particle dynamics that resemble molecular dynamics. Recently, nonlinear dynamics have provided some useful tools for understanding the relationship between the microscopic and macroscopic points of view. Chaos and fractals play key roles in this new understanding. Non-equilibrium phase-space averages look very different from their equilibrium counterparts. Away from equilibrium the smooth phase-space distributions are replaced by fractional-dimensional singular distributions that exhibit time irreversibility.
Cloud Macroscopic Organization: Order Emerging from Randomness
NASA Technical Reports Server (NTRS)
Yuan, Tianle
2011-01-01
Clouds play a central role in many aspects of the climate system and their forms and shapes are remarkably diverse. Appropriate representation of clouds in climate models is a major challenge because cloud processes span at least eight orders of magnitude in spatial scales. Here we show that there exists order in cloud size distribution of low-level clouds, and that it follows a power-law distribution with exponent gamma close to 2. gamma is insensitive to yearly variations in environmental conditions, but has regional variations and land-ocean contrasts. More importantly, we demonstrate this self-organizing behavior of clouds emerges naturally from a complex network model with simple, physical organizing principles: random clumping and merging. We also demonstrate symmetry between clear and cloudy skies in terms of macroscopic organization because of similar fundamental underlying organizing principles. The order in the apparently complex cloud-clear field thus has its root in random local interactions. Studying cloud organization with complex network models is an attractive new approach that has wide applications in climate science. We also propose a concept of cloud statistic mechanics approach. This approach is fully complementary to deterministic models, and the two approaches provide a powerful framework to meet the challenge of representing clouds in our climate models when working in tandem.
Macroscopic liquid-state molecular hydrodynamics
Keanini, R. G.; Tkacik, Peter T.; Fleischhauer, Eric; Shahinian, Hossein; Sholar, Jodie; Azimi, Farzad; Mullany, Brid
2017-01-01
Experimental evidence and theoretical modeling suggest that piles of confined, high-restitution grains, subject to low-amplitude vibration, can serve as experimentally-accessible analogs for studying a range of liquid-state molecular hydrodynamic processes. Experiments expose single-grain and multiple-grain, collective dynamic features that mimic those either observed or predicted in molecular-scale, liquid state systems, including: (i) near-collision-time-scale hydrodynamic organization of single-molecule dynamics, (ii) nonequilibrium, long-time-scale excitation of collective/hydrodynamic modes, and (iii) long-time-scale emergence of continuum, viscous flow. In order to connect directly observable macroscale granular dynamics to inaccessible and/or indirectly measured molecular hydrodynamic processes, we recast traditional microscale equilibrium and nonequilibrium statistical mechanics for dense, interacting microscale systems into self-consistent, macroscale form. The proposed macroscopic models, which appear to be new with respect to granular physics, and which differ significantly from traditional kinetic-theory-based, macroscale statistical mechanics models, are used to rigorously derive the continuum equations governing viscous, liquid-like granular flow. The models allow physically-consistent interpretation and prediction of observed equilibrium and non-equilibrium, single-grain, and collective, multiple-grain dynamics. PMID:28139711
Anwar, S.; Cortis, A.; Sukop, M.
2008-10-20
Lattice Boltzmann models simulate solute transport in porous media traversed by conduits. Resulting solute breakthrough curves are fitted with Continuous Time Random Walk models. Porous media are simulated by damping flow inertia and, when the damping is large enough, a Darcy's Law solution instead of the Navier-Stokes solution normally provided by the lattice Boltzmann model is obtained. Anisotropic dispersion is incorporated using a direction-dependent relaxation time. Our particular interest is to simulate transport processes outside the applicability of the standard Advection-Dispersion Equation (ADE) including eddy mixing in conduits. The ADE fails to adequately fit any of these breakthrough curves.
NASA Astrophysics Data System (ADS)
Frost, M.; Sedlák, P.; Kruisová, A.; Landa, M.
2014-07-01
Self-expanding stents or stentgrafts made from Nitinol superelastic alloy are widely used for a less invasive treatment of disease-induced localized flow constriction in the cardiovascular system. The therapy is based on insertion of a stent into a blood vessel to maintain the inner diameter of the vessel; it provides highly effective results at minimal cost and with reduced hospital stays. However, since stent is an external mechanical healing tool implemented into human body for quite a long time, information on the mechanical performance of it is of fundamental importance with respect to patient's safety and comfort. Advantageously, computational structural analysis can provide valuable information on the response of the product in an environment where in vivo experimentation is extremely expensive or impossible. With this motivation, a numerical model of a particular braided self-expanding stent was developed. As a reasonable approximation substantially reducing computational demands, the stent was considered to be composed of a set of helical springs with specific constrains reflecting geometry of the structure. An advanced constitutive model for NiTi-based shape memory alloys including R-phase transition was employed in analysis. Comparison to measurements shows a very good match between the numerical solution and experimental results. Relation between diameter of the stent and uniform radial pressure on its surface is estimated. Information about internal phase and stress state of the material during compression loading provided by the model is used to estimate fatigue properties of the stent during cyclic loading.
Bioreaction Engineering Leading to Efficient Synthesis of L-Glyceraldehyd-3-Phosphate.
Molla, Getachew S; Kinfu, Birhanu M; Chow, Jennifer; Streit, Wolfgang; Wohlgemuth, Roland; Liese, Andreas
2017-03-01
Enantiopure L-glyceraldehyde-3-phosphate (L-GAP) is a useful building block in natural biological and synthetic processes. A biocatalytic process using glycerol kinase from Cellulomonas sp. (EC 2.7.1.30) catalyzed phosphorylation of L-glyceraldehyde (L-GA) by ATP is used for the synthesis of L-GAP. L-GAP has a half-life of 6.86 h under reaction conditions. The activity of this enzyme depends on the Mg(2+) to ATP molar ratio showing maximum activity at the optimum molar ratio of 0.7. A kinetic model is developed and validated showing a 2D correlation of 99.9% between experimental and numerical data matrices. The enzyme exhibits inhibition by ADP, AMP, methylglyoxal and Ca(2+) , but not by L-GAP and inorganic orthophosphate. Moreover, equal amount of Ca(2+) exerts a different degree of inhibition relative to the activity without the addition of Ca(2+) depending on the Mg(2+) to ATP molar ratio. If the Mg(2+) to ATP molar ratio is set to be at the optimum value or less, inorganic hexametaphosphate (PPi6) suppresses the enzyme activity; otherwise PPi6 enhances the enzyme activity. Based on reaction engineering parameters such as conversion, selectivity and specific productivity, evaluation of different reactor types reveals that batchwise operation via stirred-tank reactor is the most efficient process for the synthesis of L-GAP.
Takahashi, Maria Beatriz; Leme, Jaci; Caricati, Celso Pereira; Tonso, Aldo; Fernández Núñez, Eutimio Gustavo; Rocha, José Celso
2015-06-01
Currently, mammalian cells are the most utilized hosts for biopharmaceutical production. The culture media for these cell lines include commonly in their composition a pH indicator. Spectroscopic techniques are used for biopharmaceutical process monitoring, among them, UV-Vis spectroscopy has found scarce applications. This work aimed to define artificial neural networks architecture and fit its parameters to predict some nutrients and metabolites, as well as viable cell concentration based on UV-Vis spectral data of mammalian cell bioprocess using phenol red in culture medium. The BHK-21 cell line was used as a mammalian cell model. Off-line spectra of supernatant samples taken from batches performed at different dissolved oxygen concentrations in two bioreactor configurations and with two pH control strategies were used to define two artificial neural networks. According to absolute errors, glutamine (0.13 ± 0.14 mM), glutamate (0.02 ± 0.02 mM), glucose (1.11 ± 1.70 mM), lactate (0.84 ± 0.68 mM) and viable cell concentrations (1.89 10(5) ± 1.90 10(5) cell/mL) were suitably predicted. The prediction error averages for monitored variables were lower than those previously reported using different spectroscopic techniques in combination with partial least squares or artificial neural network. The present work allows for UV-VIS sensor development, and decreases cost related to nutrients and metabolite quantifications.
New Tests of Macroscopic Local Realism
NASA Astrophysics Data System (ADS)
Reid, M. D.
We show that quantum mechanics predicts an Einstein-Podolsky-Rosen paradox (EPR), and also a contradiction with local hidden variable theories, for photon number measurements which have limited resolving power, to the point of imposing an uncertainty in the photon number result which is macroscopic in absolute terms. We show how this can be interpreted as a failure of a new, very strong premise, called macroscopic local realism. We link this premise to the Schrodinger-cat paradox. Our proposed experiments ensure all fields incident on each measurement apparatus are macroscopic. We show that an alternative measurement scheme corresponds to balanced homodyne detection of quadrature phase amplitudes. The implication is that where either EPR correlations or failure of local realism is predicted for quadrature phase amplitude measurements, one can potentially perform a modified experiment which would lead to conclusions about the much stronger premise of macroscopic local realism.
Rodríguez-Morales, Olivia; Carrillo-Sánchez, Silvia C.; García-Mendoza, Humberto; Aranda-Fraustro, Alberto; Ballinas-Verdugo, Martha A.; Alejandre-Aguilar, Ricardo; Rosales-Encina, José Luis; Arce-Fonseca, Minerva
2013-01-01
The dog is considered the main domestic reservoir for Trypanosoma cruzi infection and a suitable experimental animal model to study the pathological changes during the course of Chagas disease (CD). Vaccine development is one of CD prevention methods to protect people at risk. Two plasmids containing genes encoding a trans-sialidase protein (TcSP) and an amastigote-specific glycoprotein (TcSSP4) were used as DNA vaccines in a canine model. Splenomegaly was not found in either of the recombinant plasmid-immunized groups; however, cardiomegaly was absent in animals immunized only with the plasmid containing the TcSSP4 gene. The inflammation of subendocardial and myocardial tissues was prevented only with the immunization with TcSSP4 gene. In conclusion, the vaccination with these genes has a partial protective effect on the enlargement of splenic and cardiac tissues during the chronic CD and on microscopic hearth damage, since both plasmids prevented splenomegaly but only one avoided cardiomegaly, and the lesions in heart tissue of dog immunized with plasmid containing the TcSSP4 gene covered only subepicardial tissue. PMID:24163822
NASA Astrophysics Data System (ADS)
Franchi, Bruno; Lorenzani, Silvia
2016-06-01
In this paper, we study the homogenization of a set of Smoluchowski's discrete diffusion-coagulation equations modeling the aggregation and diffusion of β -amyloid peptide (Aβ ), a process associated with the development of Alzheimer's disease. In particular, we define a periodically perforated domain Ω _{ɛ }, obtained by removing from the fixed domain Ω (the cerebral tissue) infinitely many small holes of size ɛ (the neurons), which support a non-homogeneous Neumann boundary condition describing the production of Aβ by the neuron membranes. Then, we prove that, when ɛ → 0, the solution of this micromodel two-scale converges to the solution of a macromodel asymptotically consistent with the original one. Indeed, the information given on the microscale by the non-homogeneous Neumann boundary condition is transferred into a source term appearing in the limiting (homogenized) equations. Furthermore, on the macroscale, the geometric structure of the perforated domain induces a correction in that the scalar diffusion coefficients defined at the microscale are replaced by tensorial quantities.
Noise-driven interfaces and their macroscopic representation
NASA Astrophysics Data System (ADS)
Dentz, Marco; Neuweiler, Insa; Méheust, Yves; Tartakovsky, Daniel M.
2016-11-01
We study the macroscopic representation of noise-driven interfaces in stochastic interface growth models in (1 +1 ) dimensions. The interface is characterized macroscopically by saturation, which represents the fluctuating sharp interface by a smoothly varying phase field with values between 0 and 1. We determine the one-point interface height statistics for the Edwards-Wilkinson (EW) and Kadar-Paris-Zhang (KPZ) models in order to determine explicit deterministic equations for the phase saturation for each of them. While we obtain exact results for the EW model, we develop a Gaussian closure approximation for the KPZ model. We identify an interface compression term, which is related to mass transfer perpendicular to the growth direction, and a diffusion term that tends to increase the interface width. The interface compression rate depends on the mesoscopic mass transfer process along the interface and in this sense provides a relation between meso- and macroscopic interface dynamics. These results shed light on the relation between mesoscale and macroscale interface models, and provide a systematic framework for the upscaling of stochastic interface dynamics.
Macroscopic quantum phenomena from the large N perspective
NASA Astrophysics Data System (ADS)
Chou, C. H.; Hu, B. L.; Subaşi, Y.
2011-07-01
Macroscopic quantum phenomena (MQP) is a relatively new research venue, with exciting ongoing experiments and bright prospects, yet with surprisingly little theoretical activity. What makes MQP intellectually stimulating is because it is counterpoised against the traditional view that macroscopic means classical. This simplistic and hitherto rarely challenged view need be scrutinized anew, perhaps with much of the conventional wisdoms repealed. In this series of papers we report on a systematic investigation into some key foundational issues of MQP, with the hope of constructing a viable theoretical framework for this new endeavour. The three major themes discussed in these three essays are the large N expansion, the correlation hierarchy and quantum entanglement for systems of 'large' sizes, with many components or degrees of freedom. In this paper we use different theories in a variety of contexts to examine the conditions or criteria whereby a macroscopic quantum system may take on classical attributes, and, more interestingly, that it keeps some of its quantum features. The theories we consider here are, the O(N) quantum mechanical model, semiclassical stochastic gravity and gauge / string theories; the contexts include that of a 'quantum roll' in inflationary cosmology, entropy generation in quantum Vlasov equation for plasmas, the leading order and next-to-leading order large N behaviour, and hydrodynamic / thermodynamic limits. The criteria for classicality in our consideration include the use of uncertainty relations, the correlation between classical canonical variables, randomization of quantum phase, environment-induced decoherence, decoherent history of hydrodynamic variables, etc. All this exercise is to ask only one simple question: Is it really so surprising that quantum features can appear in macroscopic objects? By examining different representative systems where detailed theoretical analysis has been carried out, we find that there is no a priori
Thermodynamics of Bioreactions.
Held, Christoph; Sadowski, Gabriele
2016-06-07
Thermodynamic principles have been applied to enzyme-catalyzed reactions since the beginning of the 1930s in an attempt to understand metabolic pathways. Currently, thermodynamics is also applied to the design and analysis of biotechnological processes. The key thermodynamic quantity is the Gibbs energy of reaction, which must be negative for a reaction to occur spontaneously. However, the application of thermodynamic feasibility studies sometimes yields positive Gibbs energies of reaction even for reactions that are known to occur spontaneously, such as glycolysis. This article reviews the application of thermodynamics in enzyme-catalyzed reactions. It summarizes the basic thermodynamic relationships used for describing the Gibbs energy of reaction and also refers to the nonuniform application of these relationships in the literature. The review summarizes state-of-the-art approaches that describe the influence of temperature, pH, electrolytes, solvents, and concentrations of reacting agents on the Gibbs energy of reaction and, therefore, on the feasibility and yield of biological reactions.
NASA Astrophysics Data System (ADS)
Wu, Y.; Chen, G. L.; Hui, X. D.; Liu, C. T.; Lin, Y.; Shang, X. C.; Lu, Z. P.
2009-10-01
Based on mechanical instability of individual shear transformation zones (STZs), a quantitative link between the microplastic instability and macroscopic deformation behavior of metallic glasses was proposed. Our analysis confirms that macroscopic metallic glasses comprise a statistical distribution of STZ embryos with distributed values of activation energy, and the microplastic instability of all the individual STZs dictates the macroscopic deformation behavior of amorphous solids. The statistical model presented in this paper can successfully reproduce the macroscopic stress-strain curves determined experimentally and readily be used to predict strain-rate effects on the macroscopic responses with the availability of the material parameters at a certain strain rate, which offer new insights into understanding the actual deformation mechanism in amorphous solids.
Macroscopic Description for Networks of Spiking Neurons
NASA Astrophysics Data System (ADS)
Montbrió, Ernest; Pazó, Diego; Roxin, Alex
2015-04-01
A major goal of neuroscience, statistical physics, and nonlinear dynamics is to understand how brain function arises from the collective dynamics of networks of spiking neurons. This challenge has been chiefly addressed through large-scale numerical simulations. Alternatively, researchers have formulated mean-field theories to gain insight into macroscopic states of large neuronal networks in terms of the collective firing activity of the neurons, or the firing rate. However, these theories have not succeeded in establishing an exact correspondence between the firing rate of the network and the underlying microscopic state of the spiking neurons. This has largely constrained the range of applicability of such macroscopic descriptions, particularly when trying to describe neuronal synchronization. Here, we provide the derivation of a set of exact macroscopic equations for a network of spiking neurons. Our results reveal that the spike generation mechanism of individual neurons introduces an effective coupling between two biophysically relevant macroscopic quantities, the firing rate and the mean membrane potential, which together govern the evolution of the neuronal network. The resulting equations exactly describe all possible macroscopic dynamical states of the network, including states of synchronous spiking activity. Finally, we show that the firing-rate description is related, via a conformal map, to a low-dimensional description in terms of the Kuramoto order parameter, called Ott-Antonsen theory. We anticipate that our results will be an important tool in investigating how large networks of spiking neurons self-organize in time to process and encode information in the brain.
NASA Astrophysics Data System (ADS)
Shang, P.; Lu, Y.; Jaffe, R.; Du, Y.; Findlay, R.
2015-12-01
In order to address the effects of agricultural land use on stream water dissolved organic matter (DOM), we sampled a regional group of second to third order streams draining watersheds along a gradient of percentage agricultural lands in northwestern Alabama, USA. Samples were collected under baseflow conditions, five different times over the year 2014. We analyzed dissolved organic carbon (DOC) concentrations, DOM optical properties (i.e. ultraviolet-visible and fluorescence spectrophotometry), and DOM bioreactivity over the course of 22 d incubation. We found that air temperature and antecedent precipitation intensity (API) were two major factors positively controlling DOC concentrations. High DOC concentrations were associated with high fluorescence index values, low percent contributions from terrestrially derived humic-like DOM fluorescence component (C1), and high percent contributions from microbially derived humic-like DOM fluorescence component (C3). We suggest that elevated microbial DOM production under high temperature and API was the primary reason for DOC enrichment in stream water. Percentage agricultural land was the secondary predictor of DOM characteristics. The percentages of forest land use within watersheds positively correlated with percent protein-like DOM fluorescence component (C4). DOC concentrations and relative abundance of humic-like DOM fluorescence components (C1, C2 and C3) were higher in agricultural streams than in forested streams, which could be attributed to flow path differences between agricultural and forested watersheds. Larger amount and percentage of bioreactive DOC was observed in agricultural streams, which might decrease oxygen level and impact fluvial ecosystem in downstream regions during degradation.
Macroscopic Quantum Coherence and Computing
2010-02-17
A. Gubrud, A. J. Berkley, J. R. Anderson, C. J. Lobb, and F. C. Wellstood, IEEE Trans AppI Supr 11,998 (2001) [2] J. M. Martinis, S. Nam, J. Aumentado...al., Phys. Rev. Lett. 87, 217003 (2001) [5] M. Savolainen, et. al., to be published in Appi . Phys. A (2004), cond-mat/031 1383 Modelling the current
Nanoplasmon-enabled macroscopic thermal management
Jonsson, Gustav Edman; Miljkovic, Vladimir; Dmitriev, Alexandre
2014-01-01
In numerous applications of energy harvesting via transformation of light into heat the focus recently shifted towards highly absorptive nanoplasmonic materials. It is currently established that noble metals-based absorptive plasmonic platforms deliver significant light-capturing capability and can be viewed as super-absorbers of optical radiation. Naturally, approaches to the direct experimental probing of macroscopic temperature increase resulting from these absorbers are welcomed. Here we derive a general quantitative method of characterizing heat-generating properties of optically absorptive layers via macroscopic thermal imaging. We further monitor macroscopic areas that are homogeneously heated by several degrees with nanostructures that occupy a mere 8% of the surface, leaving it essentially transparent and evidencing significant heat generation capability of nanoplasmon-enabled light capture. This has a direct bearing to a large number of applications where thermal management is crucial. PMID:24870613
Entanglement routers using macroscopic singlets.
Bayat, Abolfazl; Bose, Sougato; Sodano, Pasquale
2010-10-29
We propose a mechanism where high entanglement between very distant boundary spins is generated by suddenly connecting two long Kondo spin chains. We show that this procedure provides an efficient way to route entanglement between multiple distant sites. We observe that the key features of the entanglement dynamics of the composite spin chain are well described by a simple model of two singlets, each formed by two spins. The proposed routing mechanism is a footprint of the emergence of a Kondo cloud in a Kondo system and can be engineered and observed in varied physical settings.
Microscopic versus macroscopic approaches to non-equilibrium systems
NASA Astrophysics Data System (ADS)
Derrida, Bernard
2011-01-01
The one-dimensional symmetric simple exclusion process (SSEP) is one of the very few exactly soluble models of non-equilibrium statistical physics. It describes a system of particles which diffuse with hard core repulsion on a one-dimensional lattice in contact with two reservoirs of particles at unequal densities. The goal of this paper is to review the two main approaches which lead to the exact expression of the large deviation functional of the density of the SSEP in its steady state: a microscopic approach (based on the matrix product ansatz and an additivity property) and a macroscopic approach (based on the macroscopic fluctuation theory of Bertini, De Sole, Gabrielli, Jona-Lasinio and Landim).
Indirect measurement of interfacial melting from macroscopic ice observations.
Saruya, Tomotaka; Kurita, Kei; Rempel, Alan W
2014-06-01
Premelted water that is adsorbed to particle surfaces and confined to capillary regions remains in the liquid state well below the bulk melting temperature and can supply the segregated growth of ice lenses. Using macroscopic measurements of ice-lens initiation position in step-freezing experiments, we infer how the nanometer-scale thicknesses of premelted films depend on temperature depression below bulk melting. The interfacial interactions between ice, liquid, and soda-lime glass particles exhibit a power-law behavior that suggests premelting in our system is dominated by short-range electrostatic forces. Using our inferred film thicknesses as inputs to a simple force-balance model with no adjustable parameters, we obtain good quantitative agreement between numerical predictions and observed ice-lens thickness. Macroscopic observations of lensing behavior have the potential as probes of premelting behavior in other systems.
Nonlocal correlations in a macroscopic measurement scenario
NASA Astrophysics Data System (ADS)
Kunkri, Samir; Banik, Manik; Ghosh, Sibasish
2017-02-01
Nonlocality is one of the main characteristic features of quantum systems involving more than one spatially separated subsystem. It is manifested theoretically as well as experimentally through violation of some local realistic inequality. On the other hand, classical behavior of all physical phenomena in the macroscopic limit gives a general intuition that any physical theory for describing microscopic phenomena should resemble classical physics in the macroscopic regime, the so-called macrorealism. In the 2-2-2 scenario (two parties, with each performing two measurements and each measurement having two outcomes), contemplating all the no-signaling correlations, we characterize which of them would exhibit classical (local realistic) behavior in the macroscopic limit. Interestingly, we find correlations which at the single-copy level violate the Bell-Clauser-Horne-Shimony-Holt inequality by an amount less than the optimal quantum violation (i.e., Cirel'son bound 2 √{2 } ), but in the macroscopic limit gives rise to a value which is higher than 2 √{2 } . Such correlations are therefore not considered physical. Our study thus provides a sufficient criterion to identify some of unphysical correlations.
Macroscopic Quantum Cotunneling of Phase Slips
NASA Astrophysics Data System (ADS)
Belkin, Andrey; Belkin, Maxim; Vakaryuk, Victor; Khlebnikov, Sergei; Bezryadin, Alexey
2014-03-01
Quantum phenomena that do not have analogues in the classical world include quantum superposition and tunneling. Despite significant efforts invested into demonstration of quantum effects at the macroscopic level, the main principles that govern the transition from classical to quantum are not well understood. Here we report a study of macroscopic quantum tunneling of phase slips that involve both superconducting and normal degrees of freedom in a superconducting nanowire loop. We discover that in addition to single phase slips that unwind the phase difference along the loop by 2 π, there are transitions that change the phase by 4 π. Experimentally we identify the regime in which, surprisingly, 4 π phase slips are more likely than 2 π ones. We interpret our observations in terms of macroscopic cotunneling effect defined as an exact synchronization of two macroscopic phase slip events. The work was supported by grant the DOE Award No. DE-FG0207ER46453, and the NSF No. DMR10-05645
[Macroscopic hematuria in an adolescent in Chad].
Ballivet de Régloix, S; Maurin, O; Douniama Ondaï, C
2012-01-01
We report the case of a 16-year-old Chadian boy referred for chronic macroscopic hematuria and dysuria, diagnosed as urinary schistosomiasis, contracted while bathing in contaminated fresh water. The diagnostic approach and treatment in light of the limited resources available in Africa are described in detail.
Berkeley Experiments on Superfluid Macroscopic Quantum Effects
Packard, Richard
2006-09-07
This paper provides a brief history of the evolution of the Berkeley experiments on macroscopic quantum effects in superfluid helium. The narrative follows the evolution of the experiments proceeding from the detection of single vortex lines to vortex photography to quantized circulation in 3He to Josephson effects and superfluid gyroscopes in both 4He and 3He.
Collective Phenomena in Macroscopic Systems
NASA Astrophysics Data System (ADS)
Bertin, G.; Pozzoli, R.; Romé, M.; Sreenivasan, K. R.
2007-08-01
A hypothesis of the magnetostatic turbulence and its implications of astrophysics / D.D. Ryutov and B.A. Remingtonn-- Coherent structures and turbulence in electron plasmas / M. Rome ... [et al.] -- Self-organization of non-linear vortices in plasma lens for ion-beam-focusing in crossed radial electrical and longitudinal magnetic fields / V. Maslov, I. Onishchenko and A. Goncharov -- Collective processes at kinetic levels in dusty plasmas / P.K. Shukla and B. Eliasson -- Magnetic field generation in anisotropic relativistic plasma regimes / F. Pegoraro, F. Califano and D. del Sarto -- Generation and observation of coherent, long-lived structures in a laser-plasma channel / T. V. Liseykina ... [et al.] -- Theoretical resolution of magnetic reconnection in high energy plasmas / B. Coppi -- The power of being flat: conformal invariance in two-dimensional turbulence / A. Celani -- Stochastic resonance: from climate to biology / R. Benzi -- Energy-enstrophy theory for coupled fluid/rotating sphere system-exact solutions for super-rotations / C. C. Lim -- Thermophoretic convection of silica nanoparticles / A. Vailati ... [et al.] -- Fluctuations and pattern formation in fluids with competing interactions / A. Imperio, D. Pini and L. Reatto -- Alternatives and paradoxes in rotational and gravitational instabilities / J.P. Goedbloed -- Poynting jets and MHD winds from rapidly rotating magnetized stars / R.V.E. Lovelace, M.M. Romanova, G.V. Ustyugova and A.V. Koldoba -- Turbulence and transport in astrophysical accretion disks / J.M. Stone -- Gravitational instabilities in gaseous discs and the formation of supermassive Black Hole seeds at high redshifts / G. Lodato -- Fine Structure and Dynamics of Sunspot Penumbra / M. Ryutova, T. Berger and A. Title -- Phase Mixing in Mond / L. Ciotti, C. Nipoti and P. Londrillo -- MHD simulations of jet acceleration: the role of disk resistivity / G. Bodo ... [et al.] -- Hamiltonian structure of a collisionless reconnection model valid
Stochastic and Macroscopic Thermodynamics of Strongly Coupled Systems
NASA Astrophysics Data System (ADS)
Jarzynski, Christopher
2017-01-01
We develop a thermodynamic framework that describes a classical system of interest S that is strongly coupled to its thermal environment E . Within this framework, seven key thermodynamic quantities—internal energy, entropy, volume, enthalpy, Gibbs free energy, heat, and work—are defined microscopically. These quantities obey thermodynamic relations including both the first and second law, and they satisfy nonequilibrium fluctuation theorems. We additionally impose a macroscopic consistency condition: When S is large, the quantities defined within our framework scale up to their macroscopic counterparts. By satisfying this condition, we demonstrate that a unifying framework can be developed, which encompasses both stochastic thermodynamics at one end, and macroscopic thermodynamics at the other. A central element in our approach is a thermodynamic definition of the volume of the system of interest, which converges to the usual geometric definition when S is large. We also sketch an alternative framework that satisfies the same consistency conditions. The dynamics of the system and environment are modeled using Hamilton's equations in the full phase space.
Macroscopic invisibility cloaking of visible light
Chen, Xianzhong; Luo, Yu; Zhang, Jingjing; Jiang, Kyle; Pendry, John B.; Zhang, Shuang
2011-01-01
Invisibility cloaks, which used to be confined to the realm of fiction, have now been turned into a scientific reality thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realization of electromagnetic invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region to a few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale of centimetres and millimetres. Our work opens avenues for future applications with macroscopic cloaking devices. PMID:21285954
Macroscopic quantum mechanics in a classical spacetime.
Yang, Huan; Miao, Haixing; Lee, Da-Shin; Helou, Bassam; Chen, Yanbei
2013-04-26
We apply the many-particle Schrödinger-Newton equation, which describes the coevolution of a many-particle quantum wave function and a classical space-time geometry, to macroscopic mechanical objects. By averaging over motions of the objects' internal degrees of freedom, we obtain an effective Schrödinger-Newton equation for their centers of mass, which can be monitored and manipulated at quantum levels by state-of-the-art optomechanics experiments. For a single macroscopic object moving quantum mechanically within a harmonic potential well, its quantum uncertainty is found to evolve at a frequency different from its classical eigenfrequency-with a difference that depends on the internal structure of the object-and can be observable using current technology. For several objects, the Schrödinger-Newton equation predicts semiclassical motions just like Newtonian physics, yet quantum uncertainty cannot be transferred from one object to another.
Macroscopic Quantum Superposition in Cavity Optomechanics
NASA Astrophysics Data System (ADS)
Liao, Jie-Qiao; Tian, Lin
Quantum superposition in mechanical systems is not only a key evidence of macroscopic quantum coherence, but can also be utilized in modern quantum technology. Here we propose an efficient approach for creating macroscopically distinct mechanical superposition states in a two-mode optomechanical system. Photon hopping between the two cavity-modes is modulated sinusoidally. The modulated photon tunneling enables an ultrastrong radiation-pressure force acting on the mechanical resonator, and hence significantly increases the mechanical displacement induced by a single photon. We present systematic studies on the generation of the Yurke-Stoler-like states in the presence of system dissipations. The state generation method is general and it can be implemented with either optomechanical or electromechanical systems. The authors are supported by the National Science Foundation under Award No. NSF-DMR-0956064 and the DARPA ORCHID program through AFOSR.
Macroscopic entrainment of periodically forced oscillatory ensembles.
Popovych, Oleksandr V; Tass, Peter A
2011-03-01
Large-amplitude oscillations of macroscopic neuronal signals, such as local field potentials and electroencephalography or magnetoencephalography signals, are commonly considered as being generated by a population of mutually synchronized neurons. In a computational study in generic networks of phase oscillators and bursting neurons, however, we show that this common belief may be wrong if the neuronal population receives an external rhythmic input. The latter may stem from another neuronal population or an external, e.g., sensory or electrical, source. In that case the population field potential may be entrained by the rhythmic input, whereas the individual neurons are phase desynchronized both mutually and with their field potential. Intriguingly, the corresponding large-amplitude oscillations of the population mean field are generated by pairwise desynchronized neurons oscillating at frequencies shifted far away from the frequency of the macroscopic field potential.
Macroscopic transport by synthetic molecular machines
NASA Astrophysics Data System (ADS)
Berná, José; Leigh, David A.; Lubomska, Monika; Mendoza, Sandra M.; Pérez, Emilio M.; Rudolf, Petra; Teobaldi, Gilberto; Zerbetto, Francesco
2005-09-01
Nature uses molecular motors and machines in virtually every significant biological process, but demonstrating that simpler artificial structures operating through the same gross mechanisms can be interfaced with-and perform physical tasks in-the macroscopic world represents a significant hurdle for molecular nanotechnology. Here we describe a wholly synthetic molecular system that converts an external energy source (light) into biased brownian motion to transport a macroscopic cargo and do measurable work. The millimetre-scale directional transport of a liquid on a surface is achieved by using the biased brownian motion of stimuli-responsive rotaxanes (`molecular shuttles') to expose or conceal fluoroalkane residues and thereby modify surface tension. The collective operation of a monolayer of the molecular shuttles is sufficient to power the movement of a microlitre droplet of diiodomethane up a twelve-degree incline.
Probing Macroscopic Realism via Ramsey Correlation Measurements
NASA Astrophysics Data System (ADS)
Asadian, A.; Brukner, C.; Rabl, P.
2014-05-01
We describe a new and experimentally feasible protocol for performing fundamental tests of quantum mechanics with massive objects. In our approach, a single two-level system is used to probe the motion of a nanomechanical resonator via multiple Ramsey interference measurements. This scheme enables the measurement of modular variables of macroscopic continuous-variable systems; we show that correlations thereof violate a Leggett-Garg inequality and can be applied for tests of quantum contextuality. Our method can be implemented with a variety of different solid-state or photonic qubit-resonator systems, and it provides a clear experimental signature to distinguish the predictions of quantum mechanics from those of other alternative theories at a macroscopic scale.
Shot Noise in Linear Macroscopic Resistors
NASA Astrophysics Data System (ADS)
Gomila, G.; Pennetta, C.; Reggiani, L.; Sampietro, M.; Ferrari, G.; Bertuccio, G.
2004-06-01
We report on direct experimental evidence of shot noise in a linear macroscopic resistor. The origin of the shot noise comes from the fluctuation of the total number of charge carriers inside the resistor associated with their diffusive motion under the condition that the dielectric relaxation time becomes longer than the dynamic transit time. The present results show that neither potential barriers nor the absence of inelastic scattering are necessary to observe shot noise in electronic devices.
Polarization properties of macroscopic Bell states
Iskhakov, Timur Sh.; Chekhova, Maria V.; Leuchs, Gerd
2011-10-15
The four two-photon polarization Bell states are one of the main instruments in the toolbox of quantum optics and quantum information. In our experiment we produce their multiphoton counterparts, macroscopic Bell states. These are relevant to applications in quantum technologies because they provide efficient interactions with material quantum objects and with each other via nonlinear interactions. Furthermore, we study the polarization properties of these states using the concept of second-order degree of polarization and its higher-order generalization.
Evaluation of arthroscopy and macroscopic scoring
af Klint, Erik; Catrina, Anca I; Matt, Peter; Neregråd, Petra; Lampa, Jon; Ulfgren, Ann-Kristin; Klareskog, Lars; Lindblad, Staffan
2009-01-01
Introduction Arthroscopy is a minimally invasive technique for retrieving synovial biopsies in rheumatology during the past 20 years. Vital for its use is continual evaluation of its safety and efficacy. Important for sampling is the fact of intraarticular variation for synovial markers. For microscopic measurements scoring systems have been developed and validated, but for macroscopic evaluations there is a need for further comprehensive description and validation of equivalent scoring systems. Methods We studied the complication rate and yield of arthroscopies performed at our clinic between 1998 and 2005. We also created and evaluated a macroscopic score set of instructions for synovitis. Results Of 408 procedures, we had two major and one minor complication; two haemarthrosis and one wound infection, respectively. Pain was most often not a problem, but 12 procedures had to be prematurely ended due to pain. Yield of biopsies adequate for histology were 83% over all, 94% for knee joints and 34% for smaller joints. Video printer photographs of synovium taken during arthroscopy were jointly and individually reviewed by seven raters in several settings, and intra and inter rater variation was calculated. A macroscopic synovial scoring system for arthroscopy was created (Macro-score), based upon hypertrophy, vascularity and global synovitis. These written instructions were evaluated by five control-raters, and when evaluated individual parameters were without greater intra or inter rater variability, indicating that the score is reliable and easy to use. Conclusions In our hands rheumatologic arthroscopy is a safe method with very few complications. For knee joints it is a reliable method to retrieve representative tissue in clinical longitudinal studies. We also created an easy to use macroscopic score, that needs to be validated against other methodologies. We hope it will be of value in further developing international standards in this area. PMID:19490631
Active Polar Two-Fluid Macroscopic Dynamics
NASA Astrophysics Data System (ADS)
Pleiner, Harald; Svensek, Daniel; Brand, Helmut R.
2014-03-01
We study the dynamics of systems with a polar dynamic preferred direction. Examples include the pattern-forming growth of bacteria (in a solvent, shoals of fish (moving in water currents), flocks of birds and migrating insects (flying in windy air). Because the preferred direction only exists dynamically, but not statically, the macroscopic variable of choice is the macroscopic velocity associated with the motion of the active units. We derive the macroscopic equations for such a system and discuss novel static, reversible and irreversible cross-couplings connected to this second velocity. We find a normal mode structure quite different compared to the static descriptions, as well as linear couplings between (active) flow and e.g. densities and concentrations due to the genuine two-fluid transport derivatives. On the other hand, we get, quite similar to the static case, a direct linear relation between the stress tensor and the structure tensor. This prominent ``active'' term is responsible for many active effects, meaning that our approach can describe those effects as well. In addition, we also deal with explicitly chiral systems, which are important for many active systems. In particular, we find an active flow-induced heat current specific for the dynamic chiral polar order.
Pathways toward understanding Macroscopic Quantum Phenomena
NASA Astrophysics Data System (ADS)
Hu, B. L.; Subaşi, Y.
2013-06-01
Macroscopic quantum phenomena refer to quantum features in objects of 'large' sizes, systems with many components or degrees of freedom, organized in some ways where they can be identified as macroscopic objects. This emerging field is ushered in by several categories of definitive experiments in superconductivity, electromechanical systems, Bose-Einstein condensates and others. Yet this new field which is rich in open issues at the foundation of quantum and statistical physics remains little explored theoretically (with the important exception of the work of A J Leggett [1], while touched upon or implied by several groups of authors represented in this conference. Our attitude differs in that we believe in the full validity of quantum mechanics stretching from the testable micro to meso scales, with no need for the introduction of new laws of physics.) This talk summarizes our thoughts in attempting a systematic investigation into some key foundational issues of quantum macroscopic phenomena, with the goal of ultimately revealing or building a viable theoretical framework. Three major themes discussed in three intended essays are the large N expansion [2], the correlation hierarchy [3] and quantum entanglement [4]. We give a sketch of the first two themes and then discuss several key issues in the consideration of macro and quantum, namely, a) recognition that there exist many levels of structure in a composite body and only by judicious choice of an appropriate set of collective variables can one give the best description of the dynamics of a specific level of structure. Capturing the quantum features of a macroscopic object is greatly facilitated by the existence and functioning of these collective variables; b) quantum entanglement, an exclusively quantum feature [5], is known to persist to high temperatures [6] and large scales [7] under certain conditions, and may actually decrease with increased connectivity in a quantum network [8]. We use entanglement as a
Effects of Microstructure Variations on Macroscopic Terahertz Metafilm Properties
O'Hara, John F.; Smirnova, Evgenya; Azad, Abul K.; ...
2007-01-01
The properties of planar, single-layer metamaterials, or metafilms, are studied by varying the structural components of the split-ring resonators used to comprise the overall medium. Measurements and simulations reveal how minor design variations in split-ring resonator structures can result in significant changes in the macroscopic properties of the metafilm. A transmission-line/circuit model is also used to clarify some of the behavior and design limitations of the metafilms. Though our results are illustrated in the terahertz frequency range, the work has broader implications, particularly with respect to filtering, modulation, and switching devices.
Interdisciplinary applications of network dynamics: From microscopic to Macroscopic
NASA Astrophysics Data System (ADS)
Jeong, Hawoong
``Everything touches everything.'' We are living in a connected world, which has been modeled successfully by complex networks. Ever since, network science becomes new paradigm for understanding our connected yet complex world. After investigating network structure itself, our focus naturally moved to dynamics of/on the network because our connected world is not static but dynamic. In this presentation, we will briefly review the historical development of network science and show some applications of network dynamics ranging from microscopic (metabolic engineering, PNAS, 104 13638) to macroscopic scale (price of anarchy in transportation network, Phys.Rev.Lett. 101 128701). Supported by National Research Foundation of Korea through Grant No. 2011-0028908.
Macroscopic Fluctuation Theory for Stationary Non-Equilibrium States
NASA Astrophysics Data System (ADS)
Bertini, L.; de Sole, A.; Gabrielli, D.; Jona-Lasinio, G.; Landim, C.
2002-05-01
We formulate a dynamical fluctuation theory for stationary non-equilibrium states (SNS) which is tested explicitly in stochastic models of interacting particles. In our theory a crucial role is played by the time reversed dynamics. Within this theory we derive the following results: the modification of the Onsager-Machlup theory in the SNS; a general Hamilton-Jacobi equation for the macroscopic entropy; a non-equilibrium, nonlinear fluctuation dissipation relation valid for a wide class of systems; an H theorem for the entropy. We discuss in detail two models of stochastic boundary driven lattice gases: the zero range and the simple exclusion processes. In the first model the invariant measure is explicitly known and we verify the predictions of the general theory. For the one dimensional simple exclusion process, as recently shown by Derrida, Lebowitz, and Speer, it is possible to express the macroscopic entropy in terms of the solution of a nonlinear ordinary differential equation; by using the Hamilton-Jacobi equation, we obtain a logically independent derivation of this result.
General framework for quantum macroscopicity in terms of coherence
NASA Astrophysics Data System (ADS)
Yadin, Benjamin; Vedral, Vlatko
2016-02-01
We propose a universal language to assess macroscopic quantumness in terms of coherence, with a set of conditions that should be satisfied by any measure of macroscopic coherence. We link the framework to the resource theory of asymmetry. We show that the quantum Fisher information gives a good measure of macroscopic coherence, enabling a rigorous justification of a previously proposed measure of macroscopicity. This picture lets us draw connections between different measures of macroscopicity and evaluate them; we show that another widely studied measure fails one of our criteria.
Observation of complementarity in the macroscopic domain
Cao Dezhong; Xiong Jun; Tang Hua; Lin Lufang; Zhang Suheng; Wang Kaige
2007-09-15
Complementarity is usually considered as a phenomenon of microscopic systems. In this paper, we report an experimental observation of complementarity in correlated double-slit interference with a pseudothermal light source. The thermal light beam is divided into test and reference beams which are correlated with each other. The double slit is set in the test arm, and an interference pattern can be observed in the intensity correlation between the two arms. The experimental results show that the disappearance of the interference fringe depends on whether which-path information is gained through the reference arm. The experiment therefore shows complementarity occurring in the macroscopic domain.
Compressor Has No Moving Macroscopic Parts
NASA Technical Reports Server (NTRS)
Gasser, Max
1995-01-01
Compressor containing no moving macroscopic parts functions by alternating piston and valve actions of successive beds of magnetic particles. Fabricated easily because no need for precisely fitting parts rotating or sliding on each other. Also no need for lubricant fluid contaminating fluid to be compressed. Compressor operates continuously, eliminating troublesome on/off cycling of other compressors, and decreasing consumption of energy. Phased cells push fluid from bottom to top, adding increments of pressure. Each cell contains magnetic powder particles loose when electromagnet coil deenergized, but tightly packed when coil energized.
A Macroscopic Realization of the Weak Interaction
NASA Technical Reports Server (NTRS)
Nishimori, Arito
2003-01-01
A.J.Leggett suggested in 1977 that a permanent electric dipole moment due to the parity-nonconserving electron-nucleon interaction, even though it is extremely small, could be measured in the superfluid He-3 B because the moment should be proportional to the size of the sample in this system. If this moment is observed, it will be the first example of a macroscopic realization of the weak interaction. In our planned experiments, a high electric field of up to 6 kV/cm is applied between two parallel electrodes in the He-3 sample. We expect to observe the NMR frequency of the lowest-lying spin-wave mode trapped by the liquid crystal-like texture of the B phase rotation axis in our geometry. The interaction of the electric field and the macroscopic permanent electric dipole moment, which is oriented along the rotation axis, will cause a small change in the texture and hence a small increase in the frequency of the spin wave mode. Besides the basic ideas, we present the purpose and the design of our first cell that is under construction.
Quantum correlations of lights in macroscopic environments
NASA Astrophysics Data System (ADS)
Sua, Yong Meng
This dissertation presents a detailed study in exploring quantum correlations of lights in macroscopic environments. We have explored quantum correlations of single photons, weak coherent states, and polarization-correlated/polarization-entangled photons in macroscopic environments. These included macroscopic mirrors, macroscopic photon number, spatially separated observers, noisy photons source and propagation medium with loss or disturbances. We proposed a measurement scheme for observing quantum correlations and entanglement in the spatial properties of two macroscopic mirrors using single photons spatial compass state. We explored the phase space distribution features of spatial compass states, such as chessboard pattern by using the Wigner function. The displacement and tilt correlations of the two mirrors were manifested through the propensities of the compass states. This technique can be used to extract Einstein-Podolsky-Rosen correlations (EPR) of the two mirrors. We then formulated the discrete-like property of the propensity P b(m,n), which can be used to explore environmental perturbed quantum jumps of the EPR correlations in phase space. With single photons spatial compass state, the variances in position and momentum are much smaller than standard quantum limit when using a Gaussian TEM 00 beam. We observed intrinsic quantum correlations of weak coherent states between two parties through balanced homodyne detection. Our scheme can be used as a supplement to decoy-state BB84 protocol and differential phase-shift QKD protocol. We prepared four types of bipartite correlations +/- cos2(theta1 +/- theta 2) that shared between two parties. We also demonstrated bits correlations between two parties separated by 10 km optical fiber. The bits information will be protected by the large quantum phase fluctuation of weak coherent states, adding another physical layer of security to these protocols for quantum key distribution. Using 10 m of highly nonlinear
NASA Astrophysics Data System (ADS)
Belli, Sebastiano; Bonsignori, Riccarda; D'Auria, Giuseppe; Fant, Lorenzo; Martini, Mirco; Peirone, Simone; Donadi, Sandro; Bassi, Angelo
2016-07-01
A recent experiment [K. C. Lee et al., Science 334, 1253 (2011)], 10.1126/science.1211914 succeeded in detecting entanglement between two macroscopic specks of diamonds, separated by a macroscopic distance, at room temperature. This impressive result is a further confirmation of the validity of quantum theory in (at least parts of) the mesoscopic and macroscopic domain, and poses a challenge to collapse models, which predict a violation of the quantum superposition principle, which is bigger the larger the system. We analyze the experiment in the light of such models. We will show that the bounds placed by experimental data are weaker than those coming from matter-wave interferometry and noninterferometric tests of collapse models.
Zhang, Jie; Critchley, Lester A H; Lee, Daniel C W; Khaw, Kim S; Lee, Shara W Y
2016-10-01
To compare the performance of a bioreactance cardiac output (CO) monitor (NICOM) and transcutaneous Doppler (USCOM) during head up tilting (HUT). Healthy young adult subjects, age 22 ± 1 years, 7 male and 7 female, were tilted over 3-5 s from supine to 70° HUT, 30° HUT and back to supine. Positions were held for 3 min. Simultaneous readings of NICOM and USCOM were performed 30 s into each new position. Mean blood pressure (MBP), heart rate (HR), CO and stroke volume (SV), and thoracic fluid content (TFC) were recorded. Bland-Altman, percentage changes and analysis of variance for repeated measures were used for statistical analysis. Pre-tilt NICOM CO and SV readings (6.1 ± 1.0 L/min and 113 ± 25 ml) were higher than those from USCOM (4.1 ± 0.6 L/min and 77 ± 9 ml) (P < 0.001). Bland-Altman limits of agreement for CO were wide with a percentage error of 38 %. HUT increased MBP and HR (P < 0.001). CO and SV readings decreased with HUT. However, the percentage changes in USCOM and NICOM readings did not concur (P < 0.001). Whereas USCOM provided gravitational effect proportional changes in SV readings of 23 ± 15 % (30° half tilt) and 44 ± 11 % (70° near full tilt), NICOM changes did not being 28 ± 10 and 33 ± 11 %. TFC decreased linearly with HUT. The NICOM does not provide linear changes in SV as predicted by physiology when patients are tilted. Furthermore there is a lack of agreement with USCOM measurements at baseline and during tilting.
Macroscopic quantum entanglement in modulated optomechanics
NASA Astrophysics Data System (ADS)
Wang, Mei; Lü, Xin-You; Wang, Ying-Dan; You, J. Q.; Wu, Ying
2016-11-01
Quantum entanglement in mechanical systems is not only a key signature of macroscopic quantum effects but has wide applications in quantum technologies. Here we propose an effective approach for creating strong steady-state entanglement between two directly coupled mechanical oscillators (or a mechanical oscillator and a microwave resonator) in a modulated optomechanical system. The entanglement is achieved by combining the processes of a cavity cooling and the two-mode parametric interaction, which can surpass the bound on the maximal stationary entanglement from the two-mode parametric interaction. In principle, our proposal allows one to cool the system from an initial thermal state to an entangled state with high purity by a monochromatic driving laser. Also, the obtained entangled state can be used to implement the continuous-variable teleportation with high fidelity. Moreover, our proposal is robust against the thermal fluctuations of the mechanical modes under the condition of strong optical pumping.
Making Macroscopic Assemblies of Aligned Carbon Nanotubes
NASA Technical Reports Server (NTRS)
Smalley, Richard E.; Colbert, Daniel T.; Smith, Ken A.; Walters, Deron A.; Casavant, Michael J.; Qin, Xiaochuan; Yakobson, Boris; Hauge, Robert H.; Saini, Rajesh Kumar; Chiung, Wan-Ting; Huffman, Charles B.
2005-01-01
A method of aligning and assembling single-wall carbon nanotubes (SWNTs) to fabricate macroscopic structures has been invented. The method entails suspending SWNTs in a fluid, orienting the SWNTs by use of a magnetic and/or electric field, and then removing the aligned SWNTs from suspension in such a way as to assemble them while maintaining the alignment. SWNTs are essentially tubular extensions of fullerene molecules. It is desirable to assemble aligned SWNTs into macroscopic structures because the common alignment of the SWNTs in such a structure makes it possible to exploit, on a macroscopic scale, the unique mechanical, chemical, and electrical properties that individual oriented SWNTs exhibit at the molecular level. Because of their small size and high electrical conductivity, carbon nanotubes, and especially SWNTs, are useful for making electrical connectors in integrated circuits. Carbon nanotubes can be used as antennas at optical frequencies, and as probes in scanning tunneling microscopes, atomic-force microscopes, and the like. Carbon nanotubes can be used with or instead of carbon black in tires. Carbon nanotubes are useful as supports for catalysts. Ropes of SWNTs are metallic and, as such, are potentially useful in some applications in which electrical conductors are needed - for example, they could be used as additives in formulating electrically conductive paints. Finally, macroscopic assemblies of aligned SWNTs can serve as templates for the growth of more and larger structures of the same type. The great variety of tubular fullerene molecules and of the structures that could be formed by assembling them in various ways precludes a complete description of the present method within the limits of this article. It must suffice to present a typical example of the use of one of many possible variants of the method to form a membrane comprising SWNTs aligned substantially parallel to each other in the membrane plane. The apparatus used in this variant
Variability of macroscopic dimensions of Moso bamboo.
Cui, Le; Peng, Wanxi; Sun, Zhengjun; Sun, Zhengjun; Sun, Zhengjun; Lu, Huangfei; Chen, Guoning
2015-03-01
In order to the macroscopic geometry distributions of vascular bundles in Moso bamboo tubes. The circumference of bamboo tubes was measured, used a simple quadratic diameter formula to analyze the differences between the tubes in bamboo culm, and the arrangement of vascular bundles was investigated by cross sectional images of bamboo tubes. The results shown that the vascular bundles were differently distributed in a bamboo tube. In the outer layer, the vascular bundles had a variety of shapes, and were aligned parallel to each other. In the inner layers, the vascular bundles weren't aligned but uniform in shape. It was concluded that the vascular bundle sections arranged in parallel should be separated from the non-parallel sections for the maximum bamboo utilization.
Macromolecular recognition and macroscopic interactions by cyclodextrins.
Harada, Akira; Takashima, Yoshinori
2013-10-01
Herein macromolecular recognition by cyclodextrins (CDs) is summarized. Recognition of macromolecules by CDs is classified as main-chain recognition or side-chain recognition. We found that CDs form inclusion complexes with various polymers with high selectivity. Polyrotaxanes in which many CDs are entrapped in a polymer chain were prepared. Tubular polymers were prepared from the polyrotaxanes. CDs were found to recognize side-chains of polymers selectively. CD host polymers were found to form gels with guest polymers in water. These gels showed self-healing properties. When azobenzene was used as a guest, the gel showed sol-gel transition by photoirradiation. When ferrocene was used, redox-responsive gels were obtained. Macroscopic self-assembly through molecular recognition has been discovered. Photoswitchable gel association and dissociation have been observed.
Macroscopically local correlations can violate information causality.
Cavalcanti, Daniel; Salles, Alejo; Scarani, Valerio
2010-01-01
Although quantum mechanics is a very successful theory, its foundations are still a subject of intense debate. One of the main problems is that quantum mechanics is based on abstract mathematical axioms, rather than on physical principles. Quantum information theory has recently provided new ideas from which one could obtain physical axioms constraining the resulting statistics one can obtain in experiments. Information causality (IC) and macroscopic locality (ML) are two principles recently proposed to solve this problem. However, none of them were proven to define the set of correlations one can observe. In this study, we show an extension of IC and study its consequences. It is shown that the two above-mentioned principles are inequivalent: if the correlations allowed by nature were the ones satisfying ML, IC would be violated. This gives more confidence in IC as a physical principle, defining the possible correlation allowed by nature.
Equivalence of macroscopic and microscopic Griffith conditions for subcritical crack growth
NASA Technical Reports Server (NTRS)
Esterling, D. M.
1981-01-01
Exact relations are derived for a simple bond-snapping model of fracture and numerical results from a previous work are presented. A lattice model with a nonlinear cohesive force law is then considered. In both cases, the results confirm the equivalence of the microscopic and macroscopic Griffith conditions. The Griffith stress intensity is to be identified with the quiescent stress intensity.
Macroscopic heat transport equations and heat waves in nonequilibrium states
NASA Astrophysics Data System (ADS)
Guo, Yangyu; Jou, David; Wang, Moran
2017-03-01
Heat transport may behave as wave propagation when the time scale of processes decreases to be comparable to or smaller than the relaxation time of heat carriers. In this work, a generalized heat transport equation including nonlinear, nonlocal and relaxation terms is proposed, which sums up the Cattaneo-Vernotte, dual-phase-lag and phonon hydrodynamic models as special cases. In the frame of this equation, the heat wave propagations are investigated systematically in nonequilibrium steady states, which were usually studied around equilibrium states. The phase (or front) speed of heat waves is obtained through a perturbation solution to the heat differential equation, and found to be intimately related to the nonlinear and nonlocal terms. Thus, potential heat wave experiments in nonequilibrium states are devised to measure the coefficients in the generalized equation, which may throw light on understanding the physical mechanisms and macroscopic modeling of nanoscale heat transport.
Characterization of Macroscopic Ordering in Exciton Rings
NASA Astrophysics Data System (ADS)
Yang, Sen; Levitov, L. S.; Simons, B. D.; Gossard, A. C.
2005-03-01
Recently observed complex PL patterns in 2D QW structures exhibit the inner [1,3] and the outer [1-4] exciton rings, localized bright spots [1,3], and the macroscopically ordered exciton state (MOES) [1,3]. The latter appears at the outer ring via its fragmentation into a periodic array of aggregates. While the gross features have been explained within classical framework, attributing the inner rings to nonradiative exciton transport and cooling [1], and the outermost rings and the bright spots to macroscopic charge separation [3,4], the origin of the MOES remains unidentified [5]. Here, for the first time, we report experiments demonstrating the exciton energy modulation over the MOES as well as the phase diagram of MOES in exciton density and temperature coordinates. The experiments shed new light on the dynamical origin of MOES. Besides, we present the studies of dynamical processes within MOES including the observation of aggregate instabilities and bifurcations that point to the spontaneous character of the instability.[1] L.V. Butov, A.C. Gossard, D.S. Chemla, Nature 418, 751 (2002). [2] D. Snoke, S. Denev, Y. Liu, L. Pfeiffer, K. West, Nature 418, 754 (2002). [3] L.V. Butov, L.S. Levitov, A.V. Mintsev, B.D. Simons, A.C. Gossard, D.S. Chemla PRL 92, 117404 (2004). [4] R. Rapaport, G. Chen, D. Snoke, S.H. Simon, L. Pfeiffer, K. West, Y. Liu, S. Denev PRL 92, 117405 (2004). [5] L.S. Levitov, B.D. Simons, L.V. Butov, cond-mat/0403377.
Determining the Macroscopic Properties of Relativistic Jets
NASA Astrophysics Data System (ADS)
Hardee, P. E.
2004-08-01
The resolved relativistic jets contain structures whose observed proper motions are typically assumed to indicate the jet flow speed. In addition to structures moving with the flow, various normal mode structures such as pinching or helical and elliptical twisting can be produced by ejection events or twisting perturbations to the jet flow. The normal mode structures associated with relativistic jets, as revealed by numerical simulation, theoretical calculation, and suggested by observation, move more slowly than the jet speed. The pattern speed is related to the jet speed by the sound speed in the jet and in the surrounding medium. In the event that normal mode structures are observed, and where proper motions of pattern and flow speed are available or can be estimated, it is possible to determine the sound speed in the jet and surrounding medium. Where spatial development of normal mode structures is observed, it is possible to make inferences as to the heating rate/macroscopic viscosity of the jet fluid. Ultimately it may prove possible to separate the microscopic energization of the synchrotron radiating particles from the macroscopic heating of the jet fluid. Here I present the relevant properties of useful normal mode structures and illustrate the use of this technique. Various aspects of the work presented here have involved collaboration with I. Agudo (Max-Planck, Bonn), M.A. Aloy (Max-Planck, Garching), J. Eilek (NM Tech), J.L. Gómez (U. Valencia), P. Hughes (U. Michigan), A. Lobanov (Max-Planck, Bonn), J.M. Martí (U. Valencia), & C. Walker (NRAO).
NASA Technical Reports Server (NTRS)
Johnson, Adriel D.
1992-01-01
Conditions simulating low- and high-gravity, reveal changes in macroscopic pattern formation in selected microorganisms, but whether these structures are gravity dependent is not clear. Two theories have been identified in the fluid dynamics community which support macroscopic pattern formation. The first one is gravity dependent (fluid density models) where small concentrated regions of organisms sink unstably, and the second is gravity independent (wave reinforcement theory) where organisms align their movements in concert, such that either their swimming strokes beat in phase or their vortices entrain neighbors to follow parallel paths. Studies have shown that macroscopic pattern formation is consistent with the fluid density models for protozoa and algae and wave reinforcement hypothesis for caprine spermatozoa.
On the macroscopic quantization in mesoscopic rings and single-electron devices
NASA Astrophysics Data System (ADS)
Semenov, Andrew G.
2016-05-01
In this letter we investigate the phenomenon of macroscopic quantization and consider particle on the ring interacting with the dissipative bath as an example. We demonstrate that even in presence of environment, there is macroscopically quantized observable which can take only integer values in the zero temperature limit. This fact follows from the total angular momentum conservation combined with momentum quantization for bare particle on the ring. The nontrivial thing is that the model under consideration, including the notion of quantized observable, can be mapped onto the Ambegaokar-Eckern-Schon model of the single-electron box (SEB). We evaluate SEB observable, originating after mapping, and reveal new physics, which follows from the macroscopic quantization phenomenon and the existence of additional conservation law. Some generalizations of the obtained results are also presented.
Dissipative macroscopic quantum tunneling in type-I superconductors
Zarzuela, R.; Tejada, J.; Chudnovsky, E. M.
2011-11-01
We study macroscopic quantum tunneling of interfaces separating normal and superconducting regions in type-I superconductors. A mathematical model is developed that describes dissipative quantum escape of a two-dimensional manifold from a planar potential well. It corresponds to, e.g., a current-driven quantum depinning of the interface from a grain boundary or from an artificially manufactured pinning layer. Effective action is derived and instantons of the equations of motion are investigated. The crossover between thermal activation and quantum tunneling is studied and the crossover temperature is computed. Our results, together with recent observation of nonthermal low-temperature magnetic relaxation in lead, suggest the possibility of a controlled measurement of quantum depinning of the interface in a type-I superconductor.
Investigation of dissipative forces near macroscopic media
Becker, R.S.
1982-12-01
The interaction of classical charged particles with the fields they induce in macroscopic dielectric media is investigated. For 10- to 1000-eV electrons, the angular perturbation of the trajectory by the image potential for surface impact parameters of 50 to 100 A is shown to be of the order of 0.001 rads over a distance of 100 A. The energy loss incurred by low-energy particles due to collective excitations such as surface plasmons is shown to be observable with a transition probability of 0.01 to 0.001 (Becker, et al., 1981b). The dispersion of real surface plasmon modes in planar and cylindrical geometries is discussed and is derived for pinhole geometry described in terms of a single-sheeted hyperboloid of revolution. An experimental apparatus for the measurement of collective losses for medium-energy electrons translating close to a dielectric surface is described and discussed. Data showing such losses at electron energies of 500 to 900 eV in silver foils containing many small apertures are presented and shown to be in good agreement with classical stopping power calculations and quantum mechanical calculations carried out in the low-velocity limit. The data and calculations are compared and contrasted with earlier transmission and reflection measurements, and the course of further investigation is discussed.
The Proell Effect: A Macroscopic Maxwell's Demon
NASA Astrophysics Data System (ADS)
Rauen, Kenneth M.
2011-12-01
Maxwell's Demon is a legitimate challenge to the Second Law of Thermodynamics when the "demon" is executed via the Proell effect. Thermal energy transfer according to the Kinetic Theory of Heat and Statistical Mechanics that takes place over distances greater than the mean free path of a gas circumvents the microscopic randomness that leads to macroscopic irreversibility. No information is required to sort the particles as no sorting occurs; the entire volume of gas undergoes the same transition. The Proell effect achieves quasi-spontaneous thermal separation without sorting by the perturbation of a heterogeneous constant volume system with displacement and regeneration. The classical analysis of the constant volume process, such as found in the Stirling Cycle, is incomplete and therefore incorrect. There are extra energy flows that classical thermo does not recognize. When a working fluid is displaced across a regenerator with a temperature gradient in a constant volume system, complimentary compression and expansion work takes place that transfers energy between the regenerator and the bulk gas volumes of the hot and cold sides of the constant volume system. Heat capacity at constant pressure applies instead of heat capacity at constant volume. The resultant increase in calculated, recyclable energy allows the Carnot Limit to be exceeded in certain cycles. Super-Carnot heat engines and heat pumps have been designed and a US patent has been awarded.
Macroscopic superpositions and gravimetry with quantum magnetomechanics
NASA Astrophysics Data System (ADS)
Johnsson, Mattias T.; Brennen, Gavin K.; Twamley, Jason
2016-11-01
Precision measurements of gravity can provide tests of fundamental physics and are of broad practical interest for metrology. We propose a scheme for absolute gravimetry using a quantum magnetomechanical system consisting of a magnetically trapped superconducting resonator whose motion is controlled and measured by a nearby RF-SQUID or flux qubit. By driving the mechanical massive resonator to be in a macroscopic superposition of two different heights our we predict that our interferometry protocol could, subject to systematic errors, achieve a gravimetric sensitivity of Δg/g ~ 2.2 × 10‑10 Hz‑1/2, with a spatial resolution of a few nanometres. This sensitivity and spatial resolution exceeds the precision of current state of the art atom-interferometric and corner-cube gravimeters by more than an order of magnitude, and unlike classical superconducting interferometers produces an absolute rather than relative measurement of gravity. In addition, our scheme takes measurements at ~10 kHz, a region where the ambient vibrational noise spectrum is heavily suppressed compared the ~10 Hz region relevant for current cold atom gravimeters.
Macroscopic superpositions and gravimetry with quantum magnetomechanics
Johnsson, Mattias T.; Brennen, Gavin K.; Twamley, Jason
2016-01-01
Precision measurements of gravity can provide tests of fundamental physics and are of broad practical interest for metrology. We propose a scheme for absolute gravimetry using a quantum magnetomechanical system consisting of a magnetically trapped superconducting resonator whose motion is controlled and measured by a nearby RF-SQUID or flux qubit. By driving the mechanical massive resonator to be in a macroscopic superposition of two different heights our we predict that our interferometry protocol could, subject to systematic errors, achieve a gravimetric sensitivity of Δg/g ~ 2.2 × 10−10 Hz−1/2, with a spatial resolution of a few nanometres. This sensitivity and spatial resolution exceeds the precision of current state of the art atom-interferometric and corner-cube gravimeters by more than an order of magnitude, and unlike classical superconducting interferometers produces an absolute rather than relative measurement of gravity. In addition, our scheme takes measurements at ~10 kHz, a region where the ambient vibrational noise spectrum is heavily suppressed compared the ~10 Hz region relevant for current cold atom gravimeters. PMID:27869142
Macroscopic car condensation in a parking garage.
Ha, Meesoon; Den Nijs, Marcel
2002-09-01
An asymmetric exclusion process type process, where cars move forward along a closed road that starts and terminates at a parking garage, displays dynamic phase transitions into two types of condensate phases where the garage becomes macroscopically occupied. The total car density rho(o) and the exit probability alpha from the garage are the two control parameters. At the transition, the number of parked cars N(p) diverges in both cases, with the length of the road N(s), as N(p) approximately N(y(p))(s) with y(p)=1/2. Towards the transition, the number of parked cars vanishes as N(p) approximately epsilon(beta) with beta=1, epsilon=/alpha-alpha(*)/ or epsilon=|rho(*)(o)-rho(o)/ being the distance from the transition. The transition into the normal phase represents also the onset of transmission of information through the garage. This gives rise to unusual parked car autocorrelations and car density profiles near the garage, which depend strongly on the group velocity of the fluctuations along the road.
Sean Strasburg; Ronald C. Davidson
2000-05-30
The macroscopic warm-fluid model developed by Lund and Davidson [Phys.Plasmas 5, 3028 (1998)] is used in the smooth-focusing approximation to investigate detailed stability properties of an intense charged particle beam with pressure anisotropy, assuming small-amplitude electrostatic pertubations about a waterbag equilibrium.
Chen, Meilian; Jaffé, Rudolf
2014-09-15
Dissolved organic carbon (DOC) measurements and optical properties were applied to assess the photo- and bio-reactivity of dissolved organic matter (DOM) from different sources, including biomass leaching, soil leaching and surface waters in a subtropical wetland ecosystem. Samples were exposed to light and/or dark incubated through controlled laboratory experiments. Changes in DOC, ultraviolet (UV-Vis) visible absorbance, and excitation-emission matrix (EEM) fluorescence combined with parallel factor analysis (PARAFAC) were performed to assess sample degradation. Degradation experiments showed that while significant amounts of DOC were consumed during bio-incubation for biomass leachates, a higher degree of bio-recalcitrance for soil leachate and particularly surface waters was displayed. Photo- and bio-humification transformations were suggested for sawgrass, mangrove, and seagrass leachates, as compared to substantial photo-degradation and very little to almost no change after bio-incubation for the other samples. During photo-degradation in most cases the EEM-PARAFAC components displayed photo-decay as compared to a few cases which featured photo-production. In contrast during bio-incubation most EEM-PARAFAC components proved to be mostly bio-refractory although some increases and decreases in abundance were also observed. Furthermore, the sequential photo- followed by bio-degradation showed, with some exceptions, a "priming effect" of light exposure on the bio-degradation of DOM, and the combination of these two processes resulted in a DOM composition more similar to that of the natural surface water for the different sub-environments. In addition, for leachate samples there was a general enrichment of one of the EEM-PARAFAC humic-like component (Ex/Em: <260(305)/416 nm) during photo-degradation and an enrichment of a microbial humc-like component (Ex/Em: <260(325)/406 nm and of a tryptophan-like component (Ex/Em: 300/342 nm) during the bio-degradation process
State-space based analysis and forecasting of macroscopic road safety trends in Greece.
Antoniou, Constantinos; Yannis, George
2013-11-01
In this paper, macroscopic road safety trends in Greece are analyzed using state-space models and data for 52 years (1960-2011). Seemingly unrelated time series equations (SUTSE) models are developed first, followed by richer latent risk time-series (LRT) models. As reliable estimates of vehicle-kilometers are not available for Greece, the number of vehicles in circulation is used as a proxy to the exposure. Alternative considered models are presented and discussed, including diagnostics for the assessment of their model quality and recommendations for further enrichment of this model. Important interventions were incorporated in the models developed (1986 financial crisis, 1991 old-car exchange scheme, 1996 new road fatality definition) and found statistically significant. Furthermore, the forecasting results using data up to 2008 were compared with final actual data (2009-2011) indicating that the models perform properly, even in unusual situations, like the current strong financial crisis in Greece. Forecasting results up to 2020 are also presented and compared with the forecasts of a model that explicitly considers the currently on-going recession. Modeling the recession, and assuming that it will end by 2013, results in more reasonable estimates of risk and vehicle-kilometers for the 2020 horizon. This research demonstrates the benefits of using advanced state-space modeling techniques for modeling macroscopic road safety trends, such as allowing the explicit modeling of interventions. The challenges associated with the application of such state-of-the-art models for macroscopic phenomena, such as traffic fatalities in a region or country, are also highlighted. Furthermore, it is demonstrated that it is possible to apply such complex models using the relatively short time-series that are available in macroscopic road safety analysis.
Sweeney, Sinbad; Berhanu, Deborah; Misra, Superb K.; Thorley, Andrew J.; Valsami-Jones, Eugenia; Tetley, Teresa D.
2015-01-01
Multiwalled carbon nanotube (MWCNT) length is suggested to critically determine their pulmonary toxicity. This stems from in vitro and in vivo rodent studies and in vitro human studies using cell lines (typically cancerous). There is little data using primary human lung cells. We addressed this knowledge gap, using highly relevant, primary human alveolar cell models exposed to precisely synthesized and thoroughly characterized MWCNTs. In this work, transformed human alveolar type-I-like epithelial cells (TT1), primary human alveolar type-II epithelial cells (ATII) and alveolar macrophages (AM) were treated with increasing concentrations of MWCNTs before measuring cytotoxicity, inflammatory mediator release and MAP kinase signalling. Strikingly, we observed that short MWCNTs (~0.6 µm in length) induced significantly greater responses from the epithelial cells, whilst AM were particularly susceptible to long MWCNTs (~20 µm). These differences in the pattern of mediator release were associated with alternative profiles of JNK, p38 and ERK1/2 MAP kinase signal transduction within each cell type. This study, using highly relevant target human alveolar cells and well defined and characterized MWCNTs, shows marked cellular responses to the MWCNTs that vary according to the target cell type, as well as the aspect ratio of the MWCNT. PMID:25780270
Newton-Dame, Remle; McVeigh, Katharine H.; Schreibstein, Lauren; Perlman, Sharon; Lurie-Moroni, Elizabeth; Jacobson, Laura; Greene, Carolyn; Snell, Elisabeth; Thorpe, Lorna E.
2016-01-01
Macroscope covered 10% of primary care providers and 15% of all adult patients in NYC in 2013 (8–47% of patients by neighborhood). Data completeness varied by domain from 98% for blood pressure among patients with hypertension to 33% for depression screening. Discussion: Design and validation efforts undertaken by NYC are described here to provide one potential blueprint for leveraging EHRs for population health monitoring. To replicate a model like NYC Macroscope, jurisdictions should establish buy-in; build informatics capacity; use standard, simple case defnitions; establish documentation quality thresholds; restrict to primary care providers; and weight the sample to a target population. PMID:28154835
NASA Astrophysics Data System (ADS)
Lester, D. R.; Trefry, M. G.; Metcalfe, G.
2016-11-01
The macroscopic spreading and mixing of solute plumes in saturated porous media is ultimately controlled by processes operating at the pore scale. Whilst the conventional picture of pore-scale mechanical dispersion and molecular diffusion leading to persistent hydrodynamic dispersion is well accepted, this paradigm is inherently two-dimensional (2D) in nature and neglects important three-dimensional (3D) phenomena. We discuss how the kinematics of steady 3D flow at the pore scale generate chaotic advection-involving exponential stretching and folding of fluid elements-the mechanisms by which it arises and implications of microscopic chaos for macroscopic dispersion and mixing. Prohibited in steady 2D flow due to topological constraints, these phenomena are ubiquitous due to the topological complexity inherent to all 3D porous media. Consequently 3D porous media flows generate profoundly different fluid deformation and mixing processes to those of 2D flow. The interplay of chaotic advection and broad transit time distributions can be incorporated into a continuous-time random walk (CTRW) framework to predict macroscopic solute mixing and spreading. We show how these results may be generalised to real porous architectures via a CTRW model of fluid deformation, leading to stochastic models of macroscopic dispersion and mixing which both honour the pore-scale kinematics and are directly conditioned on the pore-scale architecture.
NASA Astrophysics Data System (ADS)
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.
Experimental demonstration of macroscopic quantum coherence in Gaussian states
Marquardt, Christoph; Leuchs, Gerd; Andersen, Ulrik L.; Takeno, Yuishi; Yukawa, Mitsuyoshi; Yonezawa, Hidehiro; Furusawa, Akira
2007-09-15
We witness experimentally the presence of macroscopic coherence in Gaussian quantum states using a recently proposed criterion [E. G. Cavalcanti and M. D. Reid, Phys. Rev. Lett. 97 170405 (2006)]. The macroscopic coherence stems from interference between macroscopically distinct states in phase space, and we prove experimentally that a coherent state contains these features with a distance in phase space of 0.51{+-}0.02 shot noise units. This is surprising because coherent states are generally considered being at the border between classical and quantum states, not yet displaying any nonclassical effect. For squeezed and entangled states the effect may be larger but depends critically on the state purity.
Terahertz Science and Technology of Macroscopically Aligned Carbon Nanotube Films
NASA Astrophysics Data System (ADS)
Kono, Junichiro
One of the outstanding challenges in nanotechnology is how to assemble individual nano-objects into macroscopic architectures while preserving their extraordinary properties. For example, the one-dimensional character of electrons in individual carbon nanotubes leads to extremely anisotropic transport, optical, and magnetic phenomena, but their macroscopic manifestations have been limited. Here, we describe methods for preparing macroscopic films, sheets, and fibers of highly aligned carbon nanotubes and their applications to basic and applied terahertz studies. Sufficiently thick films act as ideal terahertz polarizers, and appropriately doped films operate as polarization-sensitive, flexible, powerless, and ultra-broadband detectors. Together with recently developed chirality enrichment methods, these developments will ultimately allow us to study dynamic conductivities of interacting one-dimensional electrons in macroscopic single crystals of single-chirality single-wall carbon nanotubes.
Macroscopic quantum tunnelling of protons in the KHCO 3 crystal
NASA Astrophysics Data System (ADS)
Fillaux, François; Cousson, Alain; Gutmann, Matthias J.
2006-06-01
Macroscopic quantum entanglement reveals an unforeseen mechanism for proton transfer across hydrogen bonds in the solid state. We utilize neutron scattering techniques to study proton dynamics in the crystal of potassiumhydrogencarbonate (KHCO 3) composed of small planar centrosymmetric dimer entities ( linked by moderately strong hydrogen bonds. All protons are indistinguishable, they behave as fermions, and they are degenerate. The sublattice of protons is a superposition of macroscopic single-particle states. At elevated temperature, protons are progressively transferred to secondary sites at ≈0.6 Å from the main position, via tunnelling along hydrogen bonds. The macroscopic quantum entanglement, still observed at 300 K, reveals that proton transfer is a coherent process throughout the crystal arising from a superposition of macroscopic tunnelling states.
Anatomy of the ethmoid: CT, endoscopic, and macroscopic
Terrier, F.; Weber, W.; Ruefenacht, D.; Porcellini, B.
1985-03-01
The authors illustrate the normal CT anatomy of the ethmoid region and correlate it with the endoscopic and macroscopic anatomy to define landmarks that can be recognized on CT and during endoscopically controlled transnasal ethmoidectomy.
Large Deviations for the Macroscopic Motion of an Interface
NASA Astrophysics Data System (ADS)
Birmpa, P.; Dirr, N.; Tsagkarogiannis, D.
2017-03-01
We study the most probable way an interface moves on a macroscopic scale from an initial to a final position within a fixed time in the context of large deviations for a stochastic microscopic lattice system of Ising spins with Kac interaction evolving in time according to Glauber (non-conservative) dynamics. Such interfaces separate two stable phases of a ferromagnetic system and in the macroscopic scale are represented by sharp transitions. We derive quantitative estimates for the upper and the lower bound of the cost functional that penalizes all possible deviations and obtain explicit error terms which are valid also in the macroscopic scale. Furthermore, using the result of a companion paper about the minimizers of this cost functional for the macroscopic motion of the interface in a fixed time, we prove that the probability of such events can concentrate on nucleations should the transition happen fast enough.
Macroscopic test of quantum mechanics versus stochastic electrodynamics
NASA Astrophysics Data System (ADS)
Chaturvedi, S.; Drummond, Peter D.
1997-02-01
We identify a test of quantum mechanics versus macroscopic local realism in the form of stochastic electrodynamics. The test uses the steady-state triple quadrature correlations of a parametric oscillator below threshold.
High-throughput imaging of adult fluorescent zebrafish with an LED fluorescence macroscope
Blackburn, Jessica S; Liu, Sali; Raimondi, Aubrey R; Ignatius, Myron S; Salthouse, Christopher D; Langenau, David M
2011-01-01
Zebrafish are a useful vertebrate model for the study of development, behavior, disease and cancer. A major advantage of zebrafish is that large numbers of animals can be economically used for experimentation; however, high-throughput methods for imaging live adult zebrafish had not been developed. Here, we describe protocols for building a light-emitting diode (LED) fluorescence macroscope and for using it to simultaneously image up to 30 adult animals that transgenically express a fluorescent protein, are transplanted with fluorescently labeled tumor cells or are tagged with fluorescent elastomers. These protocols show that the LED fluorescence macroscope is capable of distinguishing five fluorescent proteins and can image unanesthetized swimming adult zebrafish in multiple fluorescent channels simultaneously. The macroscope can be built and used for imaging within 1 day, whereas creating fluorescently labeled adult zebrafish requires 1 hour to several months, depending on the method chosen. The LED fluorescence macroscope provides a low-cost, high-throughput method to rapidly screen adult fluorescent zebrafish and it will be useful for imaging transgenic animals, screening for tumor engraftment, and tagging individual fish for long-term analysis. PMID:21293462
Dynamic nuclear polarisation by thermal mixing: quantum theory and macroscopic simulations.
Karabanov, Alexander; Kwiatkowski, Grzegorz; Perotto, Carlo U; Wiśniewski, Daniel; McMaster, Jonathan; Lesanovsky, Igor; Köckenberger, Walter
2016-11-02
A theory of dynamic nuclear polarisation (DNP) by thermal mixing is suggested based on purely quantum considerations. A minimal 6-level microscopic model is developed to test the theory and link it to the well-known thermodynamic model. Optimal conditions for the nuclear polarization enhancement and effects of inhomogeneous broadening of the electron resonance are discussed. Macroscopic simulations of nuclear polarization spectra displaying good agreement with experiments, involving BDPA and trityl free radicals, are presented.
Micro- and macroscopic photonic control of matter
NASA Astrophysics Data System (ADS)
Ryabtsev, Anton
parameters. In order for measurements not to be skewed, these interactions need to be taken into account and mitigated at the time of the experiment or handled later in data analysis and simulations. Experimental results are presented in four chapters. Chapter 2 describes two topics: (1) single-shot real-time monitoring and correction of spectral phase drifts, which commonly originate from temperature and pointing fluctuations inside the laser cavity when the pulses are generated; (2) an all-optical method for controlling the dispersion of femtosecond pulses using other pulses. Chapter 3 focuses on the effects of the propagation media--how intense laser pulses modify media and how, in turn, the media modifies them back--and how these effects can be counteracted. Self-action effects in fused silica are discussed, along with some interesting and unexpected results. A method is then proposed for mitigating self-action processes using binary modulation of the spectral phases of laser pulses. Chapter 4 outlines the design of two laser systems, which are specifically tailored for particular spectroscopic applications and incorporate the comprehensive pulse control described in previous chapters. Chapter 5 shows how control of spatial beam characteristics can be applied to measurements of the mechanical motion of microscale particles and how it can potentially be applied to molecular motion. It also describes an experiment on laser-induced flow in air in which attempts were made to control the macroscopic molecular rotation of gases. My research, with a pulse shaper as the enabling tool, provides important insights into ultrafast scientific studies by making femtosecond laser research more predictable, reliable and practical for measurement and control. In the long term, some of the research methods in this thesis may help the transition of femtosecond lasers from the laboratory environment into clinics, factories, airports, and other everyday settings.
Transport Theoretical Studies of Some Microscopic and Macroscopic Systems
NASA Astrophysics Data System (ADS)
Astwood, Alden Matthew
This dissertation is a report on theoretical transport studies of two systems of vastly different sizes. The first topic is electronic motion in quantum wires. In recent years, it has become possible to fabricate wires that are so small that quantum effects become important. The conduction properties of these wires are quite different than those of macroscopic wires. In this dissertation, we seek to understand scattering effects in quantum wires in a simple way. Some of the existing formalisms for studying transport in quantum wires are reviewed, and one such formalism is applied to calculate conductance in some simple systems. The second topic concerns animals which move in groups, such as flocking birds or schooling fish. Exact analytic calculations of the transport properties of such systems are very difficult because a flock is a system that is far from equilibrium and consists of many interacting particles. We introduce two simplified models of flocking which are amenable to analytic study. The first model consists of a set of overdamped Brownian particles that interact via spring forces. The exact solution for the probability distribution is calculated, and equations of motion for continuous coarse-grained quantities, such as the density, are obtained from the full solution. The second model consists of particles which move in one dimension at constant speed, but which change their directions at random. The flipping rates are constructed in such a way that particles tend to align their directions with each other. The model is solved exactly for one and two particles, the first two moments are obtained, and equations of motion for continuous coarse-grained quantities are written. The model cannot be solved exactly for many particles, but the first and second moments are calculated. Finally, two additional topics are briefly discussed. The first is transport in disordered lattices, and the second is a static magnetic model of flocking.
Prahalad, A K; Inmon, J; Dailey, L A; Madden, M C; Ghio, A J; Gallagher, J E
2001-07-01
Epidemiological studies demonstrate an association between increased human morbidity and mortality with exposure to air pollution particulate matter. We hypothesized that such effects may be associated with the ability of the particles to mediate generation of reactive oxygen species (ROS), either directly, via interaction with ambient oxygen or indirectly through initiation of an oxidative burst in phagocytes. To test this hypothesis, we determined 8-oxo-dG formation as a measure of direct generation of ROS, in response to particulate exposures to 2'-deoxyguanosine (dG), free and in calf thymus DNA in aerated solutions as the target molecule and cell culture, to assess the relationship between induction of oxidative damage, particulate metal content and metal bioreactivity. The HPLC-ECD technique was employed for separation and quantification of 8-oxo-dG, the most widely recognized marker of DNA oxidation. Particles used in this study include: Arizona desert dust (AZDD), coal fly ash (CFA and ECFA), oil fly ash (OFA and ROFA), and ambient air [SRM 1649 and Dusseldorf (DUSS), Germany]. The major difference between these particles is the concentration of water-soluble metals. The fly ash particulates OFA and ROFA showed a significant dose-dependent increase in dG hydroxylation to 8-oxo-dG formation over the control dG (p < 0.05), with yields 0.03 and 1.25% at the highest particulate concentration (1 mg/mL). Metal ion chelators and DMSO, a hydroxyl radical scavenger, inhibited this hydroxylation. In contrast, desert dust, coal fly ash and urban air particles induced 8-oxo-dG with yields ranging from 0.003 to 0.006%, respectively, with levels unaffected by pretreatment of the particles with metal ion chelators or addition of DMSO to the incubation mixture. When calf thymus DNA was used as a substrate, all the particles induced 8-oxo-dG in a pattern similar to that observed for dG hydroxylation, but with relatively less yield. Treatment of the particles with metal ion
On cavitation and macroscopic behaviour of amorphous polymer-rubber blends.
Belayachi, Naima; Benseddiq, Noureddine; Naït-Abdelaziz, Moussa; Hamdi, Adel
2008-04-01
The macroscopic behaviour of rubber-modified polymethyl methacrylate (PMMA) was investigated by taking into account the microdeformation mechanisms of rubber cavitation. The dependence of the macroscopic stress-strain behaviour of matrix deformation on the cavitation of rubber particles was discussed. A phenomenological elastic-viscoplastic model was used to model the behaviour of the matrix material, while the rubber particles were modelled with the hyperelasticity theory. A two-phase composite material with a periodic arrangement of reinforcing particles of a circular unit cell section was considered. Finite-element analysis was used to determine the local stresses and strains in the two-phase composite. In order to describe the cavitation of the rubber particles, a criterion of void nucleation is implemented in the finite-element (FE) code. A comparison of the numerically predicted response with experimental result indicates that the numerical homogenisation analysis gives satisfactory prediction results.
On cavitation and macroscopic behaviour of amorphous polymer-rubber blends
Belayachi, Naima; Benseddiq, Noureddine; Naït-Abdelaziz, Moussa; Hamdi, Adel
2008-01-01
The macroscopic behaviour of rubber-modified polymethyl methacrylate (PMMA) was investigated by taking into account the microdeformation mechanisms of rubber cavitation. The dependence of the macroscopic stress–strain behaviour of matrix deformation on the cavitation of rubber particles was discussed. A phenomenological elastic-viscoplastic model was used to model the behaviour of the matrix material, while the rubber particles were modelled with the hyperelasticity theory. A two-phase composite material with a periodic arrangement of reinforcing particles of a circular unit cell section was considered. Finite-element analysis was used to determine the local stresses and strains in the two-phase composite. In order to describe the cavitation of the rubber particles, a criterion of void nucleation is implemented in the finite-element (FE) code. A comparison of the numerically predicted response with experimental result indicates that the numerical homogenisation analysis gives satisfactory prediction results. PMID:27877983
NASA Astrophysics Data System (ADS)
Rowe, D. J.; McCoy, A. E.; Caprio, M. A.
2016-03-01
The nuclear collective models introduced by Bohr, Mottelson and Rainwater, together with the Mayer-Jensen shell model, have provided the central framework for the development of nuclear physics. This paper reviews the microscopic evolution of the collective models and their underlying foundations. In particular, it is shown that the Bohr-Mottelson models have expressions as macroscopic limits of microscopic models that have precisely defined expressions in many-nucleon quantum mechanics. Understanding collective models in this way is especially useful because it enables the analysis of nuclear properties in terms of them to be revisited and reassessed in the light of their microscopic foundations.
Study of Fission Barrier Heights of Uranium Isotopes by the Macroscopic-Microscopic Method
NASA Astrophysics Data System (ADS)
Zhong, Chun-Lai; Fan, Tie-Shuan
2014-09-01
Potential energy surfaces of uranium nuclei in the range of mass numbers 229 through 244 are investigated in the framework of the macroscopic-microscopic model and the heights of static fission barriers are obtained in terms of a double-humped structure. The macroscopic part of the nuclear energy is calculated according to Lublin—Strasbourg-drop (LSD) model. Shell and pairing corrections as the microscopic part are calculated with a folded-Yukawa single-particle potential. The calculation is carried out in a five-dimensional parameter space of the generalized Lawrence shapes. In order to extract saddle points on the potential energy surface, a new algorithm which can effectively find an optimal fission path leading from the ground state to the scission point is developed. The comparison of our results with available experimental data and others' theoretical results confirms the reliability of our calculations.
A review of macroscopic ductile failure criteria.
Corona, Edmundo; Reedlunn, Benjamin
2013-09-01
The objective of this work was to describe several of the ductile failure criteria com- monly used to solve practical problems. The following failure models were considered: equivalent plastic strain, equivalent plastic strain in tension, maximum shear, Mohr- Coulomb, Wellman's tearing parameter, Johnson-Cook and BCJ MEM. The document presents the main characteristics of each failure model as well as sample failure predic- tions for simple proportional loading stress histories in three dimensions and in plane stress. Plasticity calculations prior to failure were conducted with a simple, linear hardening, J2 plasticity model. The resulting failure envelopes were plotted in prin- cipal stress space and plastic strain space, where the dependence on stress triaxiality and Lode angle are clearly visible. This information may help analysts select a ductile fracture model for a practical problem and help interpret analysis results.
Studies into the averaging problem: Macroscopic gravity and precision cosmology
NASA Astrophysics Data System (ADS)
Wijenayake, Tharake S.
2016-08-01
With the tremendous improvement in the precision of available astrophysical data in the recent past, it becomes increasingly important to examine some of the underlying assumptions behind the standard model of cosmology and take into consideration nonlinear and relativistic corrections which may affect it at percent precision level. Due to its mathematical rigor and fully covariant and exact nature, Zalaletdinov's macroscopic gravity (MG) is arguably one of the most promising frameworks to explore nonlinearities due to inhomogeneities in the real Universe. We study the application of MG to precision cosmology, focusing on developing a self-consistent cosmology model built on the averaging framework that adequately describes the large-scale Universe and can be used to study real data sets. We first implement an algorithmic procedure using computer algebra systems to explore new exact solutions to the MG field equations. After validating the process with an existing isotropic solution, we derive a new homogeneous, anisotropic and exact solution. Next, we use the simplest (and currently only) solvable homogeneous and isotropic model of MG and obtain an observable function for cosmological expansion using some reasonable assumptions on light propagation. We find that the principal modification to the angular diameter distance is through the change in the expansion history. We then linearize the MG field equations and derive a framework that contains large-scale structure, but the small scale inhomogeneities have been smoothed out and encapsulated into an additional cosmological parameter representing the averaging effect. We derive an expression for the evolution of the density contrast and peculiar velocities and integrate them to study the growth rate of large-scale structure. We find that increasing the magnitude of the averaging term leads to enhanced growth at late times. Thus, for the same matter content, the growth rate of large scale structure in the MG model
Macroscopic magnetic islands and plasma energy transport
Cima, G; Porcelli, F; Rossi, E; Wootton, A J
1998-12-03
A model is presented, based on the combined effects of m=n=l magnetic island dynamics, localized heat sources, large heat diffusivity along magnetic field lines and plasma rotation, which may explain the multipeaked temperature profiles and transport barriers observed in tokamak plasmas heated by electron cyclotron resonant waves.
Bell-inequality tests with macroscopic entangled states of light
Stobinska, M.; Sekatski, P.; Gisin, N.; Buraczewski, A.; Leuchs, G.
2011-09-15
Quantum correlations may violate the Bell inequalities. Most experimental schemes confirming this prediction have been realized in all-optical Bell tests suffering from the detection loophole. Experiments which simultaneously close this loophole and the locality loophole are highly desirable and remain challenging. An approach to loophole-free Bell tests is based on amplification of the entangled photons (i.e., on macroscopic entanglement), for which an optical signal should be easy to detect. However, the macroscopic states are partially indistinguishable by classical detectors. An interesting idea to overcome these limitations is to replace the postselection by an appropriate preselection immediately after the amplification. This is in the spirit of state preprocessing revealing hidden nonlocality. Here, we examine one of the possible preselections, but the presented tools can be used for analysis of other schemes. Filtering methods making the macroscopic entanglement useful for Bell tests and quantum protocols are the subject of an intensive study in the field nowadays.
Scaling of macroscopic superpositions close to a quantum phase transition
NASA Astrophysics Data System (ADS)
Abad, Tahereh; Karimipour, Vahid
2016-05-01
It is well known that in a quantum phase transition (QPT), entanglement remains short ranged [Osterloh et al., Nature (London) 416, 608 (2005), 10.1038/416608a]. We ask if there is a quantum property entailing the whole system which diverges near this point. Using the recently proposed measures of quantum macroscopicity, we show that near a quantum critical point, it is the effective size of macroscopic superposition between the two symmetry breaking states which grows to the scale of system size, and its derivative with respect to the coupling shows both singular behavior and scaling properties.
Quasineutral Hybrid Simulation of Macroscopic Plasma.
1981-09-14
number, is evident. These observations are in agreement with the theoretical predictions nf Freidberg and Pearlstein’ and Seyler7. Figure 5 shows the...D.S. Harned, "Kink Instabilities in Long Ion Layerso, in preparation for submittal to Phys. Fluids. S. R.L. Morse and J.P. Freidberg , "Rigid Drift...Model of High-Temperature Plasma Containment", Phys. Fluids 13, pp. 531-533 (1970). 6 J.P. Freidberg and L.D. Pearlstein, "Rotational Instabilities in a
Determination of macroscopic transport coefficients of a dissipative particle dynamics solvent
NASA Astrophysics Data System (ADS)
Azarnykh, Dmitrii; Litvinov, Sergey; Bian, Xin; Adams, Nikolaus A.
2016-01-01
We present an approach to determine macroscopic transport coefficients of a dissipative particle dynamics (DPD) solvent. Shear viscosity, isothermal speed of sound, and bulk viscosity result from DPD-model input parameters and can be determined only a posteriori. For this reason approximate predictions of these quantities are desirable in order to set appropriate DPD input parameters. For the purpose of deriving an improved approximate prediction we analyze the autocorrelation of shear and longitudinal modes in Fourier space of a DPD solvent for Kolmogorov flow. We propose a fitting function with nonexponential properties which gives a good approximation to these autocorrelation functions. Given this fitting function we improve significantly the capability of a priori determination of macroscopic solvent transport coefficients in comparison to previously used exponential fitting functions.
Decoherence-free emergence of macroscopic local realism for entangled photons in a cavity
Portolan, S.; Rossi, F.; Di Stefano, O.; Savasta, S.; Girlanda, R.
2006-02-15
We investigate the influence of environmental noise on polarization entangled light generated by parametric emission in a cavity. By adopting a recent separability criterion, we show that (i) self-stimulation may suppress the detrimental influence of noise on entanglement, but (ii) once it becomes effective, a noise-equipped classical model of parametric emission provides the same results of quantum theory with respect to the separability criterion. More generally we also show that, in the macroscopic limit, it is not possible to observe violations of local realism with measurements of finite order n-particle correlations only. These results provide a prototypical case of the emergence of macroscopic local realism in the presence of strong entanglement even in the absence of decoherence.
A macroscopic relationship for preferential flow in the vadose zone: Theory and Validation
Liu, H.H.; Zhang, R.D.
2010-02-15
Preferential flow commonly observed in unsaturated soils allows rapid movement of solute from the ground surface or vadose zone to the groundwater, bypassing a significant volume of unsaturated soil and increasing the risk of groundwater contamination. A variety of evidence indicates that complex preferential flow patterns observed from fields are fractals. This paper discusses a macroscopic rela-tionship for modeling preferential flow in the vadose zone. Conceptually, the flow domain can be di-vided into active and inactive regions. Flow occurs preferentially in the active region (characterized by fractals), and inactive region is simply bypassed. The portion of the active region was found to be a power function of saturation. The validity of this macroscopic relationship is demonstrated by its consistency with field observations and the related numerical experiments.
Localization of deformation and loss of macroscopic ellipticity in microstructured solids
NASA Astrophysics Data System (ADS)
Santisi d'Avila, M. P.; Triantafyllidis, N.; Wen, G.
2016-12-01
Localization of deformation, a precursor to failure in solids, is a crucial and hence widely studied problem in solid mechanics. The continuum modeling approach of this phenomenon studies conditions on the constitutive laws leading to the loss of ellipticity in the governing equations, a property that allows for discontinuous equilibrium solutions. Micro-mechanics models and nonlinear homogenization theories help us understand the origins of this behavior and it is thought that a loss of macroscopic (homogenized) ellipticity results in localized deformation patterns. Although this is the case in many engineering applications, it raises an interesting question: is there always a localized deformation pattern appearing in solids losing macroscopic ellipticity when loaded past their critical state? In the interest of relative simplicity and analytical tractability, the present work answers this question in the restrictive framework of a layered, nonlinear (hyperelastic) solid in plane strain and more specifically under axial compression along the lamination direction. The key to the answer is found in the homogenized post-bifurcated solution of the problem, which for certain materials is supercritical (increasing force and displacement), leading to post-bifurcated equilibrium paths in these composites that show no localization of deformation for macroscopic strain well above the one corresponding to loss of ellipticity.
Probing deformed commutators with macroscopic harmonic oscillators
Bawaj, Mateusz; Biancofiore, Ciro; Bonaldi, Michele; Bonfigli, Federica; Borrielli, Antonio; Di Giuseppe, Giovanni; Marconi, Lorenzo; Marino, Francesco; Natali, Riccardo; Pontin, Antonio; Prodi, Giovanni A.; Serra, Enrico; Vitali, David; Marin, Francesco
2015-01-01
A minimal observable length is a common feature of theories that aim to merge quantum physics and gravity. Quantum mechanically, this concept is associated with a nonzero minimal uncertainty in position measurements, which is encoded in deformed commutation relations. In spite of increasing theoretical interest, the subject suffers from the complete lack of dedicated experiments and bounds to the deformation parameters have just been extrapolated from indirect measurements. As recently proposed, low-energy mechanical oscillators could allow to reveal the effect of a modified commutator. Here we analyze the free evolution of high-quality factor micro- and nano-oscillators, spanning a wide range of masses around the Planck mass mP (≈22 μg). The direct check against a model of deformed dynamics substantially lowers the previous limits on the parameters quantifying the commutator deformation. PMID:26088965
Macroscopic Stiffness of Breast Tumors Predicts Metastasis
Fenner, Joseph; Stacer, Amanda C.; Winterroth, Frank; Johnson, Timothy D.; Luker, Kathryn E.; Luker, Gary D.
2014-01-01
Mechanical properties of tumors differ substantially from normal cells and tissues. Changes in stiffness or elasticity regulate pro-metastatic behaviors of cancer cells, but effects have been documented predominantly in isolated cells or in vitro cell culture systems. To directly link relative stiffness of tumors to cancer progression, we combined a mouse model of metastatic breast cancer with ex vivo measurements of bulk moduli of freshly excised, intact tumors. We found a high, inverse correlation between bulk modulus of resected tumors and subsequent local recurrence and metastasis. More compliant tumors were associated with more frequent, larger local recurrences and more extensive metastases than mice with relatively stiff tumors. We found that collagen content of resected tumors correlated with bulk modulus values. These data establish that relative differences in tumor stiffness correspond with tumor progression and metastasis, supporting further testing and development of tumor compliance as a prognostic biomarker in breast cancer. PMID:24981707
Emergence of macroscopic directed motion in populations of motile colloids
NASA Astrophysics Data System (ADS)
Bricard, Antoine; Caussin, Jean-Baptiste; Desreumaux, Nicolas; Dauchot, Olivier; Bartolo, Denis
2013-11-01
From the formation of animal flocks to the emergence of coordinated motion in bacterial swarms, populations of motile organisms at all scales display coherent collective motion. This consistent behaviour strongly contrasts with the difference in communication abilities between the individuals. On the basis of this universal feature, it has been proposed that alignment rules at the individual level could solely account for the emergence of unidirectional motion at the group level. This hypothesis has been supported by agent-based simulations. However, more complex collective behaviours have been systematically found in experiments, including the formation of vortices, fluctuating swarms, clustering and swirling. All these (living and man-made) model systems (bacteria, biofilaments and molecular motors, shaken grains and reactive colloids) predominantly rely on actual collisions to generate collective motion. As a result, the potential local alignment rules are entangled with more complex, and often unknown, interactions. The large-scale behaviour of the populations therefore strongly depends on these uncontrolled microscopic couplings, which are extremely challenging to measure and describe theoretically. Here we report that dilute populations of millions of colloidal rolling particles self-organize to achieve coherent motion in a unique direction, with very few density and velocity fluctuations. Quantitatively identifying the microscopic interactions between the rollers allows a theoretical description of this polar-liquid state. Comparison of the theory with experiment suggests that hydrodynamic interactions promote the emergence of collective motion either in the form of a single macroscopic `flock', at low densities, or in that of a homogenous polar phase, at higher densities. Furthermore, hydrodynamics protects the polar-liquid state from the giant density fluctuations that were hitherto considered the hallmark of populations of self-propelled particles. Our
NASA Astrophysics Data System (ADS)
Li, Peng-Cheng; Liu, I.-Lin; Laughlin, Cecil; Chu, Shih-I.
2012-06-01
We present an accurate study of macroscopic high-order harmonic generation (HHG) from He atoms in intense ultrashort laser pulses. An accurate one-electron model potential is constructed for the description of the He atoms low-lying and Rydberg states. The macroscopic high-order harmonic spectra from He atoms are obtained by solving Maxwell's equation using macroscopic single-atom induced dipole moment. Macroscopic single-atom induced dipole moment can be obtained by solving accurately the time-dependent Schr"odinger equation (TDSE) using the time-dependent generalized pseudospectral method (TDGPS). This method allows accurate and efficient propagation of the wave function with a modest number of spatial grid points, leading to the efficient treatment of the macroscopic propagation effects for HHG. Our results show fine structure and significant enhancement of the intensities of the lower harmonics due to the resonance transitions between bound states. We explain the temporal and spatial characteristics of HHG by means of the wavelet time-frequency analysis. These analyses help to understand the detailed HHG mechanisms from He atoms.
Macroscopic stability of high β MAST plasmas
NASA Astrophysics Data System (ADS)
Chapman, I. T.; Cooper, W. A.; Graves, J. P.; Gryaznevich, M. P.; Hastie, R. J.; Hender, T. C.; Howell, D. F.; Hua, M.-D.; Huysmans, G. T. A.; Keeling, D. L.; Liu, Y. Q.; Meyer, H. F.; Michael, C. A.; Pinches, S. D.; Saarelma, S.; Sabbagh, S. A.; MAST Team
2011-07-01
The high-beta capability of the spherical tokamak, coupled with a suite of world-leading diagnostics on MAST, has facilitated significant improvements in the understanding of performance-limiting core instabilities in high performance plasmas. For instance, the newly installed motional Stark effect diagnostic, with radial resolution <25 mm, has enabled detailed study of saturated long-lived modes in hybrid scenarios. Similarly, the upgraded Thomson scattering system, with radial resolution <10 mm and the possibility of temporal resolution of 1 µs, has allowed detailed analysis of the density and temperature profiles during transient activity in the plasma, such as at a sawtooth crash. High resolution charge exchange recombination spectroscopy provided measurement of rotation braking induced by both applied magnetic fields and by magnetohydrodynamic (MHD) instabilities, allowing tests of neoclassical toroidal viscosity theory predictions. Finally, MAST is also equipped with internal and external coils that allow non-axisymmetric fields to be applied for active MHD spectroscopy of instabilities near the no-wall beta limit. MAST has been able to operate above the pressure at which the resonant field amplification is observed to strongly increase. In order to access such high pressures, the resistive wall mode must be damped, and so numerical modelling has focused on assessing the kinetic damping of the mode and its nonlinear interaction with other instabilities. The enhanced understanding of the physical mechanisms driving deleterious MHD activity given by these leading-edge capabilities has provided guidance to optimize operating scenarios for improved plasma performance.
From macroscopic yield criteria to atomic stresses in polymer glasses
MacNeill, David; Rottler, Joerg
2010-01-15
The relationship between macroscopic shear yield criteria and local stress distributions in deformed polymer glasses is investigated via molecular dynamics simulations on different scales of coarse-graining. Macroscopic shear stresses at the yield point obey a pressure-modified von Mises (pmvM) criterion for many different loading conditions and strain rates. Average local stresses in small volume elements obey the same yield criterion for volumes containing approx. 100 atoms or more. Qualitatively different behavior is observed on smaller scales: the average octahedral atomic shear stress has a simple linear relationship to hydrostatic pressure regardless of macroscopic stress state and failure mode. Local plastic events are identified through a threshold in the mean-squared nonaffine displacement and compared to the local stress state. We find that the pmvM criterion only predicts local yield events when stress and displacements are averaged over at least 100 atoms. By contrast, macroscopic shear yield criteria appear to lose their ability to predict plastic activity on the atomic scale.
[Macroscopic observations on corneal epithelial wound healing in the rabbit].
Hayashi, K
1991-02-01
A newly-developed macroscope was applied to observe the healing process of corneal epithelial wound in vivo. After removing epithelium of the central cornea, the changes of the corneal surface were observed with the macroscope and the findings were compared with histological examinations. At 12 hours after abrasion, areas unstained with Richardson's staining (R staining) appeared. In the histological section, a single layer of regenerating epithelial cells covered the same area. At 24 and 36 hours after abrasion, the epithelial defects became smaller but surrounding epithelium was rough and showed dot-like staining with R solution. By 2 days, the epithelial defects disappeared. On macroscopic observation, the central corneal surface showed a pavement-like appearance. Histology revealed that the regenerating epithelium still consisted of one or two layers. At 3 days, dot-like stainings were present only in the center and the corneal surface appeared considerably smooth. Histology also showed that regenerating epithelium became columnar and multilayered, thereby suggesting stratification. By 7 days, the abraded corneal surface had recovered its smooth appearance. Histologic sections also demonstrated that the epithelium had regained its normal structure. Thus, using this macroscope, findings suggesting the process of epithelial migration and proliferation could be observed.
A Macroscopic Analogue of the Nuclear Pairing Potential
ERIC Educational Resources Information Center
Dunlap, Richard A.
2013-01-01
A macroscopic system involving permanent magnets is used as an analogue to nucleons in a nucleus to illustrate the significance of the pairing interaction. This illustrates that the view of the total nuclear energy based only on the nucleon occupancy of the energy levels can yield erroneous results and it is only when the pairing interaction is…
Mesoscopic kinetic basis of macroscopic chemical thermodynamics: A mathematical theory.
Ge, Hao; Qian, Hong
2016-11-01
Gibbs' macroscopic chemical thermodynamics is one of the most important theories in chemistry. Generalizing it to mesoscaled nonequilibrium systems is essential to biophysics. The nonequilibrium stochastic thermodynamics of chemical reaction kinetics suggested a free energy balance equation dF^{(meso)}/dt=E_{in}-e_{p} in which the free energy input rate E_{in} and dissipation rate e_{p} are both non-negative, and E_{in}≤e_{p}. We prove that in the macroscopic limit by merely allowing the molecular numbers to be infinite, the generalized mesoscopic free energy F^{(meso)} converges to φ^{ss}, the large deviation rate function for the stationary distributions. This generalized macroscopic free energy φ^{ss} now satisfies a balance equation dφ^{ss}(x)/dt=cmf(x)-σ(x), in which x represents chemical concentration. The chemical motive force cmf(x) and entropy production rate σ(x) are both non-negative, and cmf(x)≤σ(x). The balance equation is valid generally in isothermal driven systems and is different from mechanical energy conservation and the first law; it is actually an unknown form of the second law. Consequences of the emergent thermodynamic quantities and equalities are further discussed. The emergent "law" is independent of underlying kinetic details. Our theory provides an example showing how a macroscopic law emerges from a level below.
Implementing the Deutsch-Jozsa algorithm with macroscopic ensembles
NASA Astrophysics Data System (ADS)
Semenenko, Henry; Byrnes, Tim
2016-05-01
Quantum computing implementations under consideration today typically deal with systems with microscopic degrees of freedom such as photons, ions, cold atoms, and superconducting circuits. The quantum information is stored typically in low-dimensional Hilbert spaces such as qubits, as quantum effects are strongest in such systems. It has, however, been demonstrated that quantum effects can be observed in mesoscopic and macroscopic systems, such as nanomechanical systems and gas ensembles. While few-qubit quantum information demonstrations have been performed with such macroscopic systems, a quantum algorithm showing exponential speedup over classical algorithms is yet to be shown. Here, we show that the Deutsch-Jozsa algorithm can be implemented with macroscopic ensembles. The encoding that we use avoids the detrimental effects of decoherence that normally plagues macroscopic implementations. We discuss two mapping procedures which can be chosen depending upon the constraints of the oracle and the experiment. Both methods have an exponential speedup over the classical case, and only require control of the ensembles at the level of the total spin of the ensembles. It is shown that both approaches reproduce the qubit Deutsch-Jozsa algorithm, and are robust under decoherence.
LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY
The sorption and desorption of Pb on RuO2 xH2O were examined kinetically and thermodynamically via spectroscopic and macroscopic investigations. X-ray absorption spectroscopy (XAS) was employed to determine the sorption mechanism with regard to identity of nearest atomic neighbo...
Stereodynamics: From elementary processes to macroscopic chemical reactions
Kasai, Toshio; Che, Dock-Chil; Tsai, Po-Yu; Lin, King-Chuen; Palazzetti, Federico; Aquilanti, Vincenzo
2015-12-31
This paper aims at discussing new facets on stereodynamical behaviors in chemical reactions, i.e. the effects of molecular orientation and alignment on reactive processes. Further topics on macroscopic processes involving deviations from Arrhenius behavior in the temperature dependence of chemical reactions and chirality effects in collisions are also discussed.
Macroscopic and histological variations in the cellular tapetum in dogs.
Yamaue, Yasuhiro; Hosaka, Yoshinao Z; Uehara, Masato
2014-08-01
We aimed to document macroscopic variations in the cellular tapetum in the dog, to provide a histologic description of the macroscopic results and to evaluate the correlation between the macroscopic appearance and aging. Fifty three dogs including 5 beagles, 1 Chihuahua and 47 mixed breeds of each gender were used. For a macroscopic study, the fresh tapetal fundi were photographed using digital camera. For a histological study, the glutaraldehyde-formalin fixed eyes were embedded in nitrocellulose and stained with hematoxylin-eosin or thionine. The normal tapetum was triangular with the rounded angles and the smooth contour. The atypical tapetum was smaller and more variable in shape, contour and color than the normal one. In severe cases, the fundus was devoid of the tapetum. The atypical tapetum tended to increase in frequency with aging. Retinal pigment epithelial cells on the normal tapetum were unpigmented. In the eye with the atypical tapetum, regardless of tapetal size and shape, unpigmented retinal pigment epithelial cells showed a similar distribution to that on the normal tapetum, even in a dog without a tapetum. Although there is a congenitally hypoplastic tapetum, the atypical tapetum tends to increase in incidence and severity with aging.
Mesoscopic kinetic basis of macroscopic chemical thermodynamics: A mathematical theory
NASA Astrophysics Data System (ADS)
Ge, Hao; Qian, Hong
2016-11-01
Gibbs' macroscopic chemical thermodynamics is one of the most important theories in chemistry. Generalizing it to mesoscaled nonequilibrium systems is essential to biophysics. The nonequilibrium stochastic thermodynamics of chemical reaction kinetics suggested a free energy balance equation d F(meso)/d t =Ein-ep in which the free energy input rate Ein and dissipation rate ep are both non-negative, and Ein≤ep . We prove that in the macroscopic limit by merely allowing the molecular numbers to be infinite, the generalized mesoscopic free energy F(meso) converges to φss, the large deviation rate function for the stationary distributions. This generalized macroscopic free energy φss now satisfies a balance equation d φss(x ) /d t =cmf(x ) -σ (x ) , in which x represents chemical concentration. The chemical motive force cmf(x ) and entropy production rate σ (x ) are both non-negative, and cmf(x )≤σ (x ) . The balance equation is valid generally in isothermal driven systems and is different from mechanical energy conservation and the first law; it is actually an unknown form of the second law. Consequences of the emergent thermodynamic quantities and equalities are further discussed. The emergent "law" is independent of underlying kinetic details. Our theory provides an example showing how a macroscopic law emerges from a level below.
Management of macroscopic haematuria in the emergency department.
Hicks, Derek; Li, Chi-Ying
2007-06-01
Macroscopic haematuria is a commonly seen condition in the emergency department (ED), which has a variety of causes. However, most importantly, macroscopic haematuria has a high diagnostic yield for urological malignancy. 30% of patients presenting with painless haematuria are found to have a malignancy. The majority of these patients can be managed in the outpatient setting. This review of current literature suggests a management pathway that can be used in the ED. A literature search was done using Medline, PubMed and Google. In men aged >60 years, the positive predictive value of macroscopic haematuria for urological malignancy is 22.1%, and in women of the same age it is 8.3%. In terms of the need for follow-up investigation, a single episode of haematuria is equally important as recurrent episodes. Baseline investigation in the ED includes full blood count, urea and electrolyte levels, midstream urine dipstick, beta human chorionic gonadotrophin, and formal microscopy, culture and sensitivities. Treatment of macroscopic haematuria aims at RESP--Resuscitation, Ensuring, Safe and Prompt. Indications for admission include clot retention, cardiovascular instability, uncontrolled pain, sepsis, acute renal failure, coagulopathy, severe comorbidity, heavy haematuria or social restrictions. Discharged patients should drink plenty of clear fluids and return for further medical attention if the following occur: clot retention, worsening haematuria despite adequate fluid intake, uncontrolled pain or fever, or inability to cope at home. Follow-up by a urological team should be promptly arranged, ideally within the 2-week cancer referral target.
NASA Astrophysics Data System (ADS)
Tertre, Emmanuel; Delville, Alfred; Prêt, Dimitri; Hubert, Fabien; Ferrage, Eric
2015-01-01
This study investigates the diffusion process of calcium cations confined in the interlayer space of 5 mm disks of vermiculite swelling clay minerals during the Na-for-Ca exchange process. Diffusion experiments were performed at four NaCl salinities (3 × 10-3, 5 × 10-2, 0.1 and 1 M) of the exchanger solution. A macroscopic analysis of the diffusion process based on the aqueous calcium concentrations released in the solution and on Ca-profiles obtained in the solid was performed using a pore diffusion model that has been classically used in the literature. The results obtained at the macroscopic scale showed that the apparent diffusion coefficients describing both aqueous and profiles data for Ca depend on the diffusion time and salinity of the aqueous reservoir. Such variations suggested that interlayer diffusion was driven by (1) the gradient of the sorbed species in the interlayer, which depends on the diffusion time due to the ion exchange equilibrium; and (2) the discontinuity, due to Donnan equilibrium, existing at the limit between the "internal disk border" and the "external disk border" in contact with the aqueous reservoir. Then, a set of molecular and Brownian dynamics simulations was used to (1) assess such interpretations and (2) quantitatively predict aqueous and profile data obtained at the macroscopic scale. For an aqueous reservoir with high salinity (1 M NaCl), a good agreement was obtained between the macroscopic data and the predictions obtained from Brownian dynamics simulations, confirming the role played by the gradient of the interlayer species that is suggested at the macroscopic scale and which is at the basis of the "surface diffusion models" published in literature. In addition, for aqueous reservoirs with lower salinity (5 × 10-2 M), the results obtained by Brownian dynamics simulations and normalized to the exchange rate measured at infinite time showed that the diffusion properties of the species in the aqueous reservoir cannot be
Basic Characteristics of a Macroscopic Measure for Detecting Abnormal Changes in a Multiagent System
Kinoshita, Tetsuo
2015-01-01
Multiagent application systems must deal with various changes in both the system and the system environment at runtime. Generally, such changes have undesirable negative effects on the system. To manage and control the system, it is important to observe and detect negative effects using an appropriate observation function of the system’s behavior. This paper focuses on the design of this function and proposes a new macroscopic measure with which to observe behavioral characteristics of a runtime multiagent system. The proposed measure is designed as the variance of fluctuation of a macroscopic activity factor of the whole system, based on theoretical analysis of the macroscopic behavioral model of a multiagent system. Experiments are conducted to investigate basic characteristics of the proposed measure, using a test bed system. The results of experiments show that the proposed measure reacts quickly and increases drastically in response to abnormal changes in the system. Hence, the proposed measure is considered a measure that can be used to detect undesirable changes in a multiagent system. PMID:25897499
Semenov, Semen; Schimpf, Martin
2004-01-01
The movement of molecules and homopolymer chains dissolved in a nonelectrolyte solvent in response to a temperature gradient is considered a consequence of temperature-induced pressure gradients in the solvent layer surrounding the solute molecules. Local pressure gradients are produced by nonuniform London-van der Waals interactions, established by gradients in the concentration (density) of solvent molecules. The density gradient is produced by variations in solvent thermal expansion within the nonuniform temperature field. The resulting expression for the velocity of the solute contains the Hamaker constants for solute-solvent and solute-solute interactions, the radius of the solute molecule, and the viscosity and cubic coefficient of thermal expansion of the solvent. In this paper we consider an additional force that arises from directional asymmetry in the interaction between solvent molecules. In a closed cell, the resulting macroscopic pressure gradient gives rise to a volume force that affects the motion of dissolved solutes. An expression for this macroscopic pressure gradient is derived and the resulting force is incorporated into the expression for the solute velocity. The expression is used to calculate thermodiffusion coefficients for polystyrene in several organic solvents. When these values are compared to those measured in the laboratory, the consistency is better than that found in previous reports, which did not consider the macroscopic pressure gradient that arises in a closed thermodiffusion cell. The model also allows for the movement of solute in either direction, depending on the relative values of the solvent and solute Hamaker constants.
NASA Astrophysics Data System (ADS)
Parrondo, Juan M. R.
2001-09-01
The role of symmetry breaking phase transitions in the Szilard engine is analyzed. It is shown that symmetry breaking is the only necessary ingredient for the engine to work. To support this idea, we show that the Ising model behaves exactly as the Szilard engine. We design a purely macroscopic Maxwell demon from an Ising model, demonstrating that a demon can operate with information about the macrostate of the system. We finally discuss some aspects of the definition of entropy and how thermodynamics should be modified to account for the variations of entropy in second-order phase transitions.
New Micro- and Macroscopic Models of Contact and Friction
1992-11-01
formulation of the problem which is as follows. 41 Find a displacement field u(x) EV , such that I j Eijktvi’juk,’dS1 + vi 1 NiNjujds =( Vi1 iN(W-XkN+Pok-Nk...T., and Rabinowicz , E., "The Nature of the Coefficient of Friction," .Journ. Appl. Phys., 24, 2, pp. 136-139, 1953. 23. Bush, A. W., Gibson, R. D...Nonlinear Friction Laws," International Journal of Engineering Science, Vol. 24, No. 11, pp. 1755-1768, 1986. 76. Rabinowicz , E., "The Nature of the
New Micro- and Macroscopic Models of Contact and Friction
1993-11-29
computationally more efficient to use a total formulation of3 the problem which is as follows. Find a displacement field u(x) EV , such thatI Jvj,,Ej1k1Uk,jdfl= v...Effect on Adhesion and Friction," Journ. of Colloid and Interface Science, 58, pp. 36-53 1977. 22. Burwell, J. T., and Rabinowicz , E., "The Nature of...Elasticity with Nonlinear Friction Laws," International Journal of Engineering Science, Vol. 24, No. 11, pp. 1755-1768, 1986. 77. Rabinowicz , E
Macroscopic control parameter for avalanche models for bursty transport
Chapman, S. C.; Rowlands, G.; Watkins, N. W.
2009-01-15
Similarity analysis is used to identify the control parameter R{sub A} for the subset of avalanching systems that can exhibit self-organized criticality (SOC). This parameter expresses the ratio of driving to dissipation. The transition to SOC, when the number of excited degrees of freedom is maximal, is found to occur when R{sub A}{yields}0. This is in the opposite sense to (Kolmogorov) turbulence, thus identifying a deep distinction between turbulence and SOC and suggesting an observable property that could distinguish them. A corollary of this similarity analysis is that SOC phenomenology, that is, power law scaling of avalanches, can persist for finite R{sub A} with the same R{sub A}{yields}0 exponent if the system supports a sufficiently large range of lengthscales, necessary for SOC to be a candidate for physical (R{sub A} finite) systems.
Zhu, Xingbao; Luo, Junli; Liu, Yun; Chen, Guolong; Liu, Song; Ruan, Qiangjin; Deng, Xunding; Wang, Dianchun; Fan, Quanshui; Pan, Xinghua
2012-04-25
The use of operating microscopes is limited by the focal length. Surgeons using these instruments cannot simultaneously view and access the surgical field and must choose one or the other. The longer focal length (more than 1 000 mm) of an operating telescope permits a position away from the operating field, above the surgeon and out of the field of view. This gives the telescope an advantage over an operating microscope. We developed a telescopic system using screen-imaging guidance and a modified portable video macroscope constructed from a Computar MLH-10 × macro lens, a DFK-21AU04 USB CCD Camera and a Dell laptop computer as monitor screen. This system was used to establish a middle cerebral artery occlusion model in rats. Results showed that magnification of the modified portable video macroscope was appropriate (5-20 ×) even though the Computar MLH-10 × macro lens was placed 800 mm away from the operating field rather than at the specified working distance of 152.4 mm with a zoom of 1-40 ×. The screen-imaging telescopic technique was clear, life-like, stereoscopic and matched the actual operation. Screen-imaging guidance led to an accurate, smooth, minimally invasive and comparatively easy surgical procedure. Success rate of the model establishment evaluated by neurological function using the modified neurological score system was 74.07%. There was no significant difference in model establishment time, sensorimotor deficit and infarct volume percentage. Our findings indicate that the telescopic lens is effective in the screen surgical operation mode referred to as "long distance observation and short distance operation" and that screen-imaging guidance using an modified portable video macroscope can be utilized for the establishment of a middle cerebral artery occlusion model and micro-neurosurgery.
Macroscopic drift current in the inverse Faraday effect
NASA Astrophysics Data System (ADS)
Hertel, Riccardo; Fähnle, Manfred
2015-01-01
The inverse Faraday effect (IFE) describes the spontaneous magnetization of a conducting or dielectric medium due to irradiation with a circularly polarized electromagnetic wave. The effect has recently been discussed in the context of laser-induced magnetic switching of solids. We analyze analytically the electron dynamics induced by a circularly polarized laser beam within the framework of plasma theory. A macroscopic drift current is obtained, which circulates around the perimeter of the laser beam. The magnetic moment due to this macroscopic current has an opposite sign and half of the magnitude of the magnetic moment that is generated directly by the IFE. This constitutes an important contribution of angular momentum transferred from the wave to the medium and a classical mechanism for the light-induced generation of magnetic fields.
Macroscopic ordering of helical pores for arraying guest molecules noncentrosymmetrically
Li, Chunji; Cho, Joonil; Yamada, Kuniyo; Hashizume, Daisuke; Araoka, Fumito; Takezoe, Hideo; Aida, Takuzo; Ishida, Yasuhiro
2015-01-01
Helical nanostructures have attracted continuous attention, not only as media for chiral recognition and synthesis, but also as motifs for studying intriguing physical phenomena that never occur in centrosymmetric systems. To improve the quality of signals from these phenomena, which is a key issue for their further exploration, the most straightforward is the macroscopic orientation of helices. Here as a versatile scaffold to rationally construct this hardly accessible structure, we report a polymer framework with helical pores that unidirectionally orient over a large area (∼10 cm2). The framework, prepared by crosslinking a supramolecular liquid crystal preorganized in a magnetic field, is chemically robust, functionalized with carboxyl groups and capable of incorporating various basic or cationic guest molecules. When a nonlinear optical chromophore is incorporated in the framework, the resultant complex displays a markedly efficient nonlinear optical output, owing to the coherence of signals ensured by the macroscopically oriented helical structure. PMID:26416086
From 1D to 3D - macroscopic nanowire aerogel monoliths
NASA Astrophysics Data System (ADS)
Cheng, Wei; Rechberger, Felix; Niederberger, Markus
2016-07-01
Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying.Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying. Electronic supplementary information (ESI) available: Experimental details, SEM and TEM images, and digital photographs. See DOI: 10.1039/c6nr04429h
Emergent thermodynamics in a system of macroscopic, chaotic surface waves
NASA Astrophysics Data System (ADS)
Welch, Kyle J.
The properties of conventional materials are inextricably linked with their molecular composition; to make water flow like wine would require changing its molecular identity. To circumvent this restriction, I have constructed and characterized a two-dimensional metafluid, so-called because its constitutive dynamics are derived not from atoms and molecules but from macroscopic, chaotic surface waves excited on a vertically agitated fluid. Unlike in conventional fluids, the viscosity and temperature of this metafluid are independently tunable. Despite this unconventional property, our system is surprisingly consistent with equilibrium thermodynamics, despite being constructed from macroscopic, non-equilibrium elements. As a programmable material, our metafluid represents a new platform on which to study complex phenomena such as self-assembly and pattern formation. We demonstrate one such application in our study of short-chain polymer analogs embedded in our system.
Macroscopic Simulation of Deformation in Soft Microporous Composites.
Evans, Jack D; Coudert, François-Xavier
2017-03-23
Soft microporous materials exhibit properties, such as gated adsorption and breathing, which are highly desirable for many applications. These properties are largely studied for single crystals; however, many potential applications expect to construct structured or composite systems, examples of which include monoliths and mixed-matrix membranes. Herein, we use finite element methods to predict the macroscopic mechanical response of composite microporous materials. This implementation connects the microscopic treatment of crystalline structures to the response of a macroscopic sample. Our simulations reveal the bulk modulus of an embedded adsorbent within a composite is affected by the thickness and properties of the encapsulating layer. Subsequently, we employ this methodology to examine mixed-matrix membranes and materials of negative linear compressibility. This application of finite element methods allows for unprecedented insight into the mechanical properties of real-world systems and supports the development of composites containing mechanically anomalous porous materials.
Macroscopic Discontinuous Shear Thickening versus Local Shear Jamming in Cornstarch
NASA Astrophysics Data System (ADS)
Fall, A.; Bertrand, F.; Hautemayou, D.; Mezière, C.; Moucheront, P.; Lemaître, A.; Ovarlez, G.
2015-03-01
We study the emergence of discontinuous shear thickening (DST) in cornstarch by combining macroscopic rheometry with local magnetic resonance imaging measurements. We bring evidence that macroscopic DST is observed only when the flow separates into a low-density flowing and a high-density jammed region. In the shear-thickened steady state, the local rheology in the flowing region is not DST but, strikingly, is often shear thinning. Our data thus show that the stress jump measured during DST, in cornstarch, does not capture a secondary, high-viscosity branch of the local steady rheology but results from the existence of a shear jamming limit at volume fractions quite significantly below random close packing.
Nonclassicality tests and entanglement witnesses for macroscopic mechanical superposition states
NASA Astrophysics Data System (ADS)
Gittsovich, Oleg; Moroder, Tobias; Asadian, Ali; Gühne, Otfried; Rabl, Peter
2015-02-01
We describe a set of measurement protocols for performing nonclassicality tests and the verification of entangled superposition states of macroscopic continuous variable systems, such as nanomechanical resonators. Following earlier works, we first consider a setup where a two-level system is used to indirectly probe the motion of the mechanical system via Ramsey measurements and discuss the application of this method for detecting nonclassical mechanical states. We then show that the generalization of this technique to multiple resonator modes allows the conditioned preparation and the detection of entangled mechanical superposition states. The proposed measurement protocols can be implemented in various qubit-resonator systems that are currently under experimental investigation and find applications in future tests of quantum mechanics at a macroscopic scale.
Toward a superconducting quantum computer. Harnessing macroscopic quantum coherence.
Tsai, Jaw-Shen
2010-01-01
Intensive research on the construction of superconducting quantum computers has produced numerous important achievements. The quantum bit (qubit), based on the Josephson junction, is at the heart of this research. This macroscopic system has the ability to control quantum coherence. This article reviews the current state of quantum computing as well as its history, and discusses its future. Although progress has been rapid, the field remains beset with unsolved issues, and there are still many new research opportunities open to physicists and engineers.
Macroscopic superposition of ultracold atoms with orbital degrees of freedom
Garcia-March, M. A.; Carr, L. D.; Dounas-Frazer, D. R.
2011-04-15
We introduce higher dimensions into the problem of Bose-Einstein condensates in a double-well potential, taking into account orbital angular momentum. We completely characterize the eigenstates of this system, delineating new regimes via both analytical high-order perturbation theory and numerical exact diagonalization. Among these regimes are mixed Josephson- and Fock-like behavior, crossings in both excited and ground states, and shadows of macroscopic superposition states.
Measurement-Induced Macroscopic Superposition States in Cavity Optomechanics
NASA Astrophysics Data System (ADS)
Hoff, Ulrich B.; Kollath-Bönig, Johann; Neergaard-Nielsen, Jonas S.; Andersen, Ulrik L.
2016-09-01
A novel protocol for generating quantum superpositions of macroscopically distinct states of a bulk mechanical oscillator is proposed, compatible with existing optomechanical devices operating in the bad-cavity limit. By combining a pulsed optomechanical quantum nondemolition (QND) interaction with nonclassical optical resources and measurement-induced feedback, the need for strong single-photon coupling is avoided. We outline a three-pulse sequence of QND interactions encompassing squeezing-enhanced cooling by measurement, state preparation, and tomography.
Enhancement of macroscopic quantum tunneling by Landau-Zener transitions.
Ankerhold, Joachim; Grabert, Hermann
2003-07-04
Motivated by recent realizations of qubits with a readout by macroscopic quantum tunneling in a Josephson junction, we study the problem of barrier penetration in the presence of coupling to a spin-1 / 2 system. It is shown that, when the diabatic potentials for fixed spin intersect in the barrier region, Landau-Zener transitions lead to an enhancement of the tunneling rate. The effect of these spin flips in imaginary time is in qualitative agreement with experimental observations.
Macroscopic inspection of ape feces: what's in a quantification method?
Phillips, Caroline A; McGrew, William C
2014-06-01
Macroscopic inspection of feces has been used to investigate primate diet. The limitations of this method to identify food-items to species level have long been recognized, but ascertaining aspects of diet (e.g., folivory) are achievable by quantifying food-items in feces. Quantification methods applied include rating food-items using a scale of abundance, estimating their percentage volume, and weighing food-items. However, verification as to whether or not composition data differ, depending on which quantification method is used during macroscopic inspection, has not been done. We analyzed feces collected from ten adult chimpanzees (Pan troglodytes schweinfurthii) of the Kanyawara community in Kibale National Park, Uganda. We compare dietary composition totals obtained from using different quantification methods and ascertain if sieve mesh size influences totals calculated. Finally, this study validates findings from direct observation of feeding by the same individuals from whom the fecal samples had been collected. Contrasting diet composition totals obtained by using different quantification methods and sieve mesh sizes can influence folivory and frugivory estimates. However, our findings were based on the assumption that fibrous matter contained pith and leaf fragments only, which remains to be verified. We advocate macroscopic inspection of feces can be a valuable tool to provide a generalized overview of dietary composition for primate populations. As most populations remain unhabituated, scrutinizing and validating indirect measures are important if they are to be applied to further understand inter- and intra-species dietary variation.
Macroscopic Quantum Phenomena from the Correlation, Coupling and Criticality Perspectives
NASA Astrophysics Data System (ADS)
Chou, C. H.; Hu, B. L.; Subaşi, Y.
2011-12-01
In this sequel paper we explore how macroscopic quantum phenomena can be measured or understood from the behavior of quantum correlations which exist in a quantum system of many particles or components and how the interaction strengths change with energy or scale, under ordinary situations and when the system is near its critical point. We use the nPI (master) effective action related to the Boltzmann-BBGKY / Schwinger-Dyson hierarchy of equations as a tool for systemizing the contributions of higher order correlation functions to the dynamics of lower order correlation functions. Together with the large N expansion discussed in our first paper [1] we explore 1) the conditions whereby an H-theorem is obtained, which can be viewed as a signifier of the emergence of macroscopic behavior in the system. We give two more examples from past work: 2) the nonequilibrium dynamics of N atoms in an optical lattice under the large Script N (field components), 2PI and second order perturbative expansions, illustrating how N and Script N enter in these three aspects of quantum correlations, coherence and coupling strength. 3) the behavior of an interacting quantum system near its critical point, the effects of quantum and thermal fluctuations and the conditions under which the system manifests infrared dimensional reduction. We also discuss how the effective field theory concept bears on macroscopic quantum phenomena: the running of the coupling parameters with energy or scale imparts a dynamical-dependent and an interaction-sensitive definition of 'macroscopia'.
Macroscopic character of composite high-temperature superconducting wires
NASA Astrophysics Data System (ADS)
Kivelson, S. A.; Spivak, B.
2015-11-01
The "d -wave" symmetry of the superconducting order in the cuprate high temperature superconductors is a well established fact [J. Tsuei and J. R. Kirtley, Rev. Mod. Phys. 72, 969 (2000), 10.1103/RevModPhys.72.969 and D. J. Vanharlingen, Rev. Mod. Phys. 67, 515 (1995), 10.1103/RevModPhys.67.515], and one which identifies them as "unconventional." However, in macroscopic contexts—including many potential applications (i.e., superconducting "wires")—the material is a composite of randomly oriented superconducting grains in a metallic matrix, in which Josephson coupling between grains mediates the onset of long-range phase coherence. [See, e.g., D. C. Larbalestier et al., Nat. Mater. 13, 375 (2014), 10.1038/nmat3887, A. P. Malozemoff, MRS Bull. 36, 601 (2011), 10.1557/mrs.2011.160, and K. Heine et al., Appl. Phys. Lett. 55, 2441 (1989), 10.1063/1.102295] Here we analyze the physics at length scales that are large compared to the size of such grains, and in particular the macroscopic character of the long-range order that emerges. While X Y -superconducting glass order and macroscopic d -wave superconductivity may be possible, we show that under many circumstances—especially when the d -wave superconducting grains are embedded in a metallic matrix—the most likely order has global s -wave symmetry.
Macroscopic description of complex adaptive networks coevolving with dynamic node states.
Wiedermann, Marc; Donges, Jonathan F; Heitzig, Jobst; Lucht, Wolfgang; Kurths, Jürgen
2015-05-01
In many real-world complex systems, the time evolution of the network's structure and the dynamic state of its nodes are closely entangled. Here we study opinion formation and imitation on an adaptive complex network which is dependent on the individual dynamic state of each node and vice versa to model the coevolution of renewable resources with the dynamics of harvesting agents on a social network. The adaptive voter model is coupled to a set of identical logistic growth models and we mainly find that, in such systems, the rate of interactions between nodes as well as the adaptive rewiring probability are crucial parameters for controlling the sustainability of the system's equilibrium state. We derive a macroscopic description of the system in terms of ordinary differential equations which provides a general framework to model and quantify the influence of single node dynamics on the macroscopic state of the network. The thus obtained framework is applicable to many fields of study, such as epidemic spreading, opinion formation, or socioecological modeling.
NASA Astrophysics Data System (ADS)
Gawad, J.; Khairullah, Md; Roose, D.; Van Bael, A.
2016-08-01
Multi-scale simulations are computationally expensive if a two-way coupling is employed. In the context of sheet metal forming simulations, a fine-scale representative volume element (RVE) crystal plasticity (CP) model would supply the Finite Element analysis with plastic properties, taking into account the evolution of crystallographic texture and other microstructural features. The main bottleneck is that the fine-scale model must be evaluated at virtually every integration point in the macroscopic FE mesh. We propose to address this issue by exploiting a verifiable assumption that fine-scale state variables of similar RVEs, as well as the derived properties, subjected to similar macroscopic boundary conditions evolve along nearly identical trajectories. Furthermore, the macroscopic field variables primarily responsible for the evolution of fine-scale state variables often feature local quasi-homogeneities. Adjacent integration points in the FE mesh can be then clustered together in the regions where the field responsible for the evolution shows low variance. This way the fine-scale evolution is tracked only at a limited number of material points and the derived plastic properties are propagated to the surrounding integration points subjected to similar deformation. Optimal configurations of the clusters vary in time as the local deformation conditions may change during the forming process, so the clusters must be periodically adapted. We consider two operations on the clusters of integration points: splitting (refinement) and merging (unrefinement). The concept is tested in the Hierarchical Multi-Scale (HMS) framework [1] that computes macroscopic deformations by means of the FEM, whereas the micro-structural evolution at the individual FE integration points is predicted by a CP model. The HMS locally and adaptively approximates homogenized stress responses of the CP model by means of analytical plastic potential or yield criterion function. Our earlier work
NASA Technical Reports Server (NTRS)
Kobayashi, Tsunehiro
1996-01-01
Quantum macroscopic motions are investigated in the scheme consisting of N-number of harmonic oscillators in terms of ultra-power representations of nonstandard analysis. Decoherence is derived from the large internal degrees of freedom of macroscopic matters.
Instability of cooperative adaptive cruise control traffic flow: A macroscopic approach
NASA Astrophysics Data System (ADS)
Ngoduy, D.
2013-10-01
This paper proposes a macroscopic model to describe the operations of cooperative adaptive cruise control (CACC) traffic flow, which is an extension of adaptive cruise control (ACC) traffic flow. In CACC traffic flow a vehicle can exchange information with many preceding vehicles through wireless communication. Due to such communication the CACC vehicle can follow its leader at a closer distance than the ACC vehicle. The stability diagrams are constructed from the developed model based on the linear and nonlinear stability method for a certain model parameter set. It is found analytically that CACC vehicles enhance the stabilization of traffic flow with respect to both small and large perturbations compared to ACC vehicles. Numerical simulation is carried out to support our analytical findings. Based on the nonlinear stability analysis, we will show analytically and numerically that the CACC system better improves the dynamic equilibrium capacity over the ACC system. We have argued that in parallel to microscopic models for CACC traffic flow, the newly developed macroscopic will provide a complete insight into the dynamics of intelligent traffic flow.
Macroscopic supramolecular assembly of rigid building blocks through a flexible spacing coating.
Cheng, Mengjiao; Shi, Feng; Li, Jianshu; Lin, Zaifu; Jiang, Chao; Xiao, Meng; Zhang, Liqun; Yang, Wantai; Nishi, Toshio
2014-05-21
Macroscopic supramolecular assembly is a promising method for manufacturing macroscopic, ordered structures for tissue-engineering scaffolds. A flexible spacing coating is shown to overcome undesired surface and size effects and to enable assembly of macroscopic cubes with host/guest groups. The assembled pairs disassembled upon introduction of competitive guest molecules, thereby demonstrating a multivalent assembly mechanism.
Monte Carlo simulation of superdiffusion and subdiffusion in macroscopically heterogeneous media
NASA Astrophysics Data System (ADS)
Zhang, Yong; Labolle, Eric M.; Pohlmann, Karl
2009-10-01
Monte Carlo simulations are developed to approximate one-dimensional superdiffusion and subdiffusion in macroscopically heterogeneous media with discontinuous or continuous transport parameters. For superdiffusion characterized by a space fractional (α-order) derivative model, one empirical reflection scheme is built to track particle trajectory across an interface with discontinuous dispersion coefficient D, where the reflection probability depends on both α and the ratio of D. Different from the superdiffusive case, anomalous diffusion described by a time fractional derivative model can be decomposed into a motion component and a hitting time process, where the discontinuity affects only the motion process, implying an efficient Monte Carlo simulation of decoupled continuous time random walks. The discontinuity of effective porosity n is also discussed, and results show the influence of the ratio of n on solute particle dynamics. In addition, for anomalous superdiffusion and subdiffusion in heterogeneous media with spatially continuous D and n, Langevin analysis reveals that the corresponding particle dynamics contain three independent stable Lévy noises scaled by D, the gradient of D, and the gradient of ln(n). A new implicit Eulerian finite difference method is also developed to solve the spatiotemporal fractional derivative models and then extensively cross verify the Lagrangian solutions. Further testing against one field example of mixed superdiffusion and subdiffusion reveals the applicability and flexibility of the novel Monte Carlo approach in simulating realistic plumes in macroscopically heterogeneous media with locally variable transport parameters.
Violation of smooth observable macroscopic realism in a harmonic oscillator.
Leshem, Amir; Gat, Omri
2009-08-14
We study the emergence of macrorealism in a harmonic oscillator subject to consecutive measurements of a squeezed action. We demonstrate a breakdown of dynamical realism in a wide parameter range that is maximized in a scaling limit of extreme squeezing, where it is based on measurements of smooth observables, implying that macroscopic realism is not valid in the harmonic oscillator. We propose an indirect experimental test of these predictions with entangled photons by demonstrating that local realism in a composite system implies dynamical realism in a subsystem.
Macroscopic test of the Aharonov-Bohm effect.
Caprez, Adam; Barwick, Brett; Batelaan, Herman
2007-11-23
The Aharonov-Bohm (AB) effect is a purely quantum mechanical effect. The original (classified as type-I) AB-phase shift exists in experimental conditions where the electromagnetic fields and forces are zero. It is the absence of forces that makes the AB effect entirely quantum mechanical. Although the AB-phase shift has been demonstrated unambiguously, the absence of forces in type-I AB effects has never been shown. Here, we report the observation of the absence of time delays associated with forces of the magnitude needed to explain the AB-phase shift for a macroscopic system.
Macroscopic Test of the Aharonov-Bohm Effect
Caprez, Adam; Barwick, Brett; Batelaan, Herman
2007-11-23
The Aharonov-Bohm (AB) effect is a purely quantum mechanical effect. The original (classified as type-I) AB-phase shift exists in experimental conditions where the electromagnetic fields and forces are zero. It is the absence of forces that makes the AB effect entirely quantum mechanical. Although the AB-phase shift has been demonstrated unambiguously, the absence of forces in type-I AB effects has never been shown. Here, we report the observation of the absence of time delays associated with forces of the magnitude needed to explain the AB-phase shift for a macroscopic system.
Dimensional Crossover in Quantum Networks: From Macroscopic to Mesoscopic Physics
NASA Astrophysics Data System (ADS)
Schopfer, Félicien; Mallet, François; Mailly, Dominique; Texier, Christophe; Montambaux, Gilles; Bäuerle, Christopher; Saminadayar, Laurent
2007-01-01
We report on magnetoconductance measurements of metallic networks of various sizes ranging from 10 to 106 plaquettes, with an anisotropic aspect ratio. Both Altshuler-Aronov-Spivak h/2e periodic oscillations and Aharonov-Bohm h/e periodic oscillations are observed for all networks. For large samples, the amplitude of both oscillations results from the incoherent superposition of contributions of phase coherent regions. When the transverse size becomes smaller than the phase coherent length Lϕ, one enters a new regime which is phase coherent (mesoscopic) along one direction and macroscopic along the other, leading to a new size dependence of the quantum oscillations.
NASA Astrophysics Data System (ADS)
Watanabe, Ikumu; Terada, Kenjiro; Neto, Eduardo Alberto de Souza; Perić, Djordje
The objective of this contribution is to develop an elastic-plastic-damage constitutive model for crystal grain and to incorporate it with two-scale finite element analyses based on mathematical homogenization method, in order to characterize the macroscopic tensile strength of polycrystalline metals. More specifically, the constitutive model for single crystal is obtained by combining hyperelasticity, a rate-independent single crystal plasticity and a continuum damage model. The evolution equations, stress update algorithm and consistent tangent are derived within the framework of standard elastoplasticity at finite strain. By employing two-scale finite element analysis, the ductile behaviour of polycrystalline metals and corresponding tensile strength are evaluated. The importance of finite element formulation is examined by comparing performance of several finite elements and their convergence behaviour is assessed with mesh refinement. Finally, the grain size effect on yield and tensile strength is analysed in order to illustrate the versatility of the proposed two-scale model.
A macroscopic non-destructive testing system based on the cantilever-sample contact resonance
NASA Astrophysics Data System (ADS)
Fu, Ji; Lin, Lizhi; Zhou, Xilong; Li, Yingwei; Li, Faxin
2012-12-01
Detecting the inside or buried defects in materials and structures is always a challenge in the field of nondestructive testing (NDT). In this paper, enlightened by the operation principle of the contact resonance force microscopy or atomic force acoustic microscopy (AFAM), we proposed a macroscopic NDT system based on contact resonance of the cantilever-sample surface to detect the local stiffness variations in materials or structures. We fabricated a piezoelectric unimorph with the dimension typically of 150 mm × 8 mm × 2 mm to act as a macroscopic cantilever, whose flexural mode vibration was driven by a wideband power amplifier together with a signal generator. The vibration signal of the macroscopic cantilever is detected by a high sensitive strain gauge bonded on the cantilever surface which is much more stable than the laser diode sensor in AFAM, thus making it very suitable for outdoor operations. Scanning is realized by a three-dimensional motorized stage with the Z axis for pressing force setting. The whole system is controlled by a LabVIEW-based homemade software. Like the AFAM, this NDT system can also work in two modes, i.e., the single-frequency mode and the resonance-tracking mode. In the latter mode, the contact stiffness at each pixel of the sample can be obtained by using the measured contact resonance frequency and a beam dynamics model. Testing results of this NDT system on a grid structure with an opaque panel show that in both modes the prefabricated defect beneath the panel can be detected and the grid structures can be clearly "seen," which indicates the validity of this NDT system. The sensitivity of this NDT system was also examined.
Micro/macroscopic fluid flow in open cell fibrous structures and porous media
NASA Astrophysics Data System (ADS)
Tamayol, Ali
Fibrous porous materials are involved in a wide range of applications including composite fabrication, filtration, compact heat exchangers, fuel cell technology, and tissue engineering to name a few. Fibrous structures, such as metalfoams, have unique characteristics such as low weight, high porosity, high mechanical strength, and high surface to volume ratio. More importantly, in many applications the fibrous microstructures can be tailored to meet a range of requirements. Therefore, fibrous materials have the potential to be used in emerging sustainable energy conversion applications. The first step for analyzing transport phenomena in porous materials is to determine the micro/macroscopic flow-field inside the medium. In applications where the porous media is confined in a channel, the system performance is tightly related to the flow properties of the porous medium and its interaction with the channel walls, i.e., macroscopic velocity distribution. Therefore, the focus of the study has been on: developing new mechanistic model(s) for determining permeability and inertial coefficient of fibrous porous materials; investigating the effects of microstructural and mechanical parameters such as porosity, fiber orientation, mechanical compression, and fiber distribution on the flow properties and pressure drop of fibrous structures; determining the macroscopic flow-field in confined porous media where the porous structure fills the channel cross-section totally or partially. A systematic approach has been followed to study different aspects of the flow through fibrous materials. The complex microstructure of real materials has been modelled using unit cells that have been assumed to be repeated throughout the media. Implementing various exact and approximate analytical techniques such as integral technique, point matching, blending rules, and scale analysis the flow properties of such media have been modelled; the targeted properties include permeability and inertial
Chung, Hayoung; Choi, Joonmyung; Yun, Jung-Hoon; Cho, Maenghyo
2016-01-01
A liquid crystal network whose chromophores are functionalized by photochromic dye exhibits light-induced mechanical behaviour. As a result, the micro-scaled thermotropic traits of the network and the macroscopic phase behaviour are both influenced as light alternates the shape of the dyes. In this paper, we present an analysis of this photomechanical behaviour based on the proposed multiscale framework, which incorporates the molecular details of microstate evolution into a continuum-based understanding. The effects of trans-to-cis photoisomerization driven by actinic light irradiation are first examined using molecular dynamics simulations, and are compared against the predictions of the classical dilution model; this reveals certain characteristics of mesogenic interaction upon isomerization, followed by changes in the polymeric structure. We then upscale the thermotropic phase-related information with the aid of a nonlinear finite element analysis; macroscopic deflection with respect to the wide ranges of temperature and actinic light intensity are thereby examined, which reveals that the classical model underestimates the true deformation. This work therefore provides measures for analysing photomechanics in general by bridging the gap between the micro- and macro-scales. PMID:26828417
A Virtual Soil System to Study Macroscopic Manifestation of Pore-Scale Biogeochemical Processes
NASA Astrophysics Data System (ADS)
Liu, C.; Fang, Y.; Shang, J.; Bailey, V. L.
2012-12-01
Mechanistic soil biogeochemical processes occur at the pore-scale that fundamentally control the moisture and CO2 fluxes at the soil and atmosphere interface. This presentation will present an on-going research to investigate pore-scale moisture migration and biogeochemical processes of organic carbon degradation, and their macroscopic manifestation in soils. Soil cores collected from Rattlesnake Mountain in southeastern Washington, USA, where a field experiment was conducted to investigate dynamic response of soil biogeochemistry to changing climate conditions, were used as an example for this study. The cores were examined using computerized x-ray tomography (XCT) to determine soil pore structures. The XCT imaging, together with various measurements of soil properties such as porosity, moisture content, organic carbon, biochemistry, etc are used to establish a virtual soil core with a high spatial resolution (~20um). The virtual soil system is then used to simulate soil moisture migration and organic carbon degradation, to identify important physical and biogeochemical factors controlling macroscopic moisture and CO2 fluxes in response to changing climate conditions, and to develop and evaluate pragmatic biogeochemical process models for larger scale applications. Core-scale measurements of CO2 flux and moisture change are used for development and validation of the process models.
NASA Astrophysics Data System (ADS)
Chung, Hayoung; Choi, Joonmyung; Yun, Jung-Hoon; Cho, Maenghyo
2016-02-01
A liquid crystal network whose chromophores are functionalized by photochromic dye exhibits light-induced mechanical behaviour. As a result, the micro-scaled thermotropic traits of the network and the macroscopic phase behaviour are both influenced as light alternates the shape of the dyes. In this paper, we present an analysis of this photomechanical behaviour based on the proposed multiscale framework, which incorporates the molecular details of microstate evolution into a continuum-based understanding. The effects of trans-to-cis photoisomerization driven by actinic light irradiation are first examined using molecular dynamics simulations, and are compared against the predictions of the classical dilution model; this reveals certain characteristics of mesogenic interaction upon isomerization, followed by changes in the polymeric structure. We then upscale the thermotropic phase-related information with the aid of a nonlinear finite element analysis; macroscopic deflection with respect to the wide ranges of temperature and actinic light intensity are thereby examined, which reveals that the classical model underestimates the true deformation. This work therefore provides measures for analysing photomechanics in general by bridging the gap between the micro- and macro-scales.
Macroscopic nanoporous graphene membranes for molecular-sieving-based gas separation
NASA Astrophysics Data System (ADS)
Boutilier, Michael; Karnik, Rohit; Hadjiconstantinou, Nicolas
2016-11-01
Nanoporous graphene membranes have the potential to exceed permeance and selectivity limits of existing gas separation membranes. This is made possible by the atomic thickness of the material, which can support sub-nanometer pores that enable molecular sieving while presenting low resistance to permeate flow. The feasibility of gas separation by graphene nanopores has been demonstrated experimentally on micron-scale areas of graphene. However, scaling up to macroscopic membrane areas presents significant challenges, including graphene imperfections and control of the selective nanopore size distribution across large areas. Towards this goal, gas permeance experiments are conducted on single and few layer graphene membranes to understand leakage pathways and a model is developed to predict conditions under which molecular sieving can occur in macroscopic membranes. Approaches to seal or mitigate the effects of micron and nanometer scale defects in graphene are investigated and methods of creating a high density of selectively permeable nanopores are explored. Experimental results demonstrating separation ratios exceeding the Knudsen effusion limit, indicating molecular sieving in agreement with the model predictions, are presented and discussed.
How does Planck’s constant influence the macroscopic world?
NASA Astrophysics Data System (ADS)
Yang, Pao-Keng
2016-09-01
In physics, Planck’s constant is a fundamental physical constant accounting for the energy-quantization phenomenon in the microscopic world. The value of Planck’s constant also determines in which length scale the quantum phenomenon will become conspicuous. Some students think that if Planck’s constant were to have a larger value than it has now, the quantum effect would only become observable in a world with a larger size, whereas the macroscopic world might remain almost unchanged. After reasoning from some basic physical principles and theories, we found that doubling Planck’s constant might result in a radical change on the geometric sizes and apparent colors of macroscopic objects, the solar spectrum and luminosity, the climate and gravity on Earth, as well as energy conversion between light and materials such as the efficiency of solar cells and light-emitting diodes. From the discussions in this paper, students can appreciate how Planck’s constant affects various aspects of the world in which we are living now.
Confocal scanning beam laser microscope/macroscope: applications in fluorescence
NASA Astrophysics Data System (ADS)
Dixon, Arthur E.; Damaskinos, Savvas; Ribes, Alfonso
1996-03-01
A new confocal scanning beam laser microscope/macroscope is described that combines the rapid scan of a scanning beam laser microscope with the large specimen capability of a scanning stage microscope. This instrument combines an infinity-corrected confocal scanning laser microscope with a scanning laser macroscope that uses a telecentric f*(Theta) laser scan lens to produce a confocal imaging system with a resolution of 0.25 microns at a field of view of 25 microns and 5 microns at a field of view of 75,000 microns. The frame rate is 5 seconds per frame for a 512 by 512 pixel image, and 25 seconds for a 2048 by 2048 pixel image. Applications in fluorescence are discussed that focus on two important advantages of the instrument over a confocal scanning laser microscope: an extremely wide range of magnification, and the ability to image very large specimens. Examples are presented of fluorescence and reflected-light images of high quality printing, fluorescence images of latent fingerprints, packaging foam, and confocal autofluorescence images of a cricket.
Duality in entanglement of macroscopic states of light
NASA Astrophysics Data System (ADS)
Lee, Su-Yong; Lee, Chang-Woo; Kurzyński, Paweł; Kaszlikowski, Dagomir; Kim, Jaewan
2016-08-01
We investigate duality in entanglement of a bipartite multiphoton system generated from a coherent state of light. The system can exhibit polarization entanglement if the two parts are distinguished by their parity, or parity entanglement if the parts are distinguished by polarization. It was shown in Phys. Rev. Lett. 110, 140404 (2013), 10.1103/PhysRevLett.110.140404 that this phenomenon can be exploited as a method to test indistinguishability of two particles and it was conjectured that one can also test indistinguishability of macroscopic systems. We propose a setup to test this conjecture. Contrary to the previous studies using two-particle interference effect as in the Hong-Ou- Mandel setup, our setup neither assumes that the tested state is composed of single particles nor requires that the total number of particles be fixed. Consequently, the notion of entanglement duality is shown to be compatible with a broader class of physical systems. Moreover, by observing duality in entanglement in the above system one can confirm that macroscopic systems exhibit quantum behavior. As a practical side, entanglement duality is a useful concept that enables adaptive conversion of entanglement of one degree of freedom (DOF) to that of another DOF according to varying quantum protocols.
Tribological behaviour of graphite powders at nano- and macroscopic scales
NASA Astrophysics Data System (ADS)
Schmitt, M.; Bistac, S.; Jradi, K.
2007-04-01
With its high resistance, good hardness and electrical conductibility in the basal plans, graphite is used for many years in various tribological fields such as seals, bearings or electrical motor brushes, and also for applications needing excellent lubrication and wearreducing properties. But thanks to its low density, graphite is at the moment destined for technologies which need a reducing of the weight combined with an enhancement of the efficiency, as it is the case in aeronautical industry. In this contexte, the friction and wear of natural (named graphite A) and synthetic (called graphites B and C) powders were evaluated, first at the macroscopic scale when sliding against steel counterfaces, under various applied normal loads. Scanning Electron Microscopy and AFM in tapping mode were used to observe the morphological modifications of the graphites. It is noticed that an enlargement of the applied normal load leads to an increase of the friction coefficient for graphites A and C; but for the graphite B, it seems that a ''limit'' load can induce a complete change of the tribological behaviour. At the same time, the nano-friction properties of these powders were evaluated by AFM measurements in contact mode, at different contact loads. As it was the case at the macroscopic scale, an increase of the nano-contact load induces higher friction coefficients. The determining of the friction and wear mechanisms of the graphite powders, as a function of both their intrinsic characteristics and the applied normal load, is then possible.
Catalytic Growth of Macroscopic Carbon Nanofibers Bodies with Activated Carbon
Abdullah, N.; Muhammad, I. S.; Hamid, S. B. Abd.; Rinaldi, A.; Su, D. S.; Schlogl, R.
2009-06-01
Carbon-carbon composite of activated carbon and carbon nanofibers have been synthesized by growing Carbon nanofiber (CNF) on Palm shell-based Activated carbon (AC) with Ni catalyst. The composites are in an agglomerated shape due to the entanglement of the defective CNF between the AC particles forming a macroscopic body. The macroscopic size will allow the composite to be used as a stabile catalyst support and liquid adsorbent. The preparation of CNT/AC nanocarbon was initiated by pre-treating the activated carbon with nitric acid, followed by impregnation of 1 wt% loading of nickel (II) nitrate solutions in acetone. The catalyst precursor was calcined and reduced at 300 deg. C for an hour in each step. The catalytic growth of nanocarbon in C{sub 2}H{sub 4}/H{sub 2} was carried out at temperature of 550 deg. C for 2 hrs with different rotating angle in the fluidization system. SEM and N{sub 2} isotherms show the level of agglomeration which is a function of growth density and fluidization of the system. The effect of fluidization by rotating the reactor during growth with different speed give a significant impact on the agglomeration of the final CNF/AC composite and thus the amount of CNFs produced. The macrostructure body produced in this work of CNF/AC composite will have advantages in the adsorbent and catalyst support application, due to the mechanical and chemical properties of the material.
Macroscopic Biological Characteristics of Individualized Therapy in Chinese Mongolian Osteopathy
NASA Astrophysics Data System (ADS)
Namula, Zhao; Mei, Wang; Li, Xue-en
Objective: Chinese Mongolian osteopathy has been passed down from ancient times and includes unique practices and favorable efficacy. In this study, we investigate the macroscopic biological characteristics of individualized Chinese Mongolian osteopathy, in order to provide new principle and methods for the treatment of bone fracture. Method: With a view to provide a vital link between nature and humans, the four stages of Chinese Mongolian osteopathy focus on the unity of the mind and body, the limbs and body organs, the body and its functions, and humans and nature. Results: We discuss the merits of individualized osteopathy in terms of the underlying concepts, and evaluate the approaches and principles of traditional medicine, as well as biomechanics. Conclusions: Individualized Mongolian osteopathy targets macroscopic biological components including dynamic reduction, natural fixation, and functional healing. Chinese Mongolian osteopathy is a natural, ecological and non-invasive osteopathy that values the link between nature and humans, including the unity of mind and body. The biological components not only serve as a foundation for Chinese Mongolian osteopathy but are also important for the future development of modern osteopathy, focusing on individualization, actualization and integration.
Is ergodicity a reasonable hypothesis for macroscopic systems?
NASA Astrophysics Data System (ADS)
Gaveau, B.; Schulman, L. S.
2015-07-01
In the physics literature "ergodicity" is sometimes taken to mean that a system, including a macroscopic one, visits all microscopic states in a relatively short time. However, many authors have realized that this is impossible and we provide a rigorous bound demonstrating this fact. A related concept is the "thermal distribution." This enters in an understanding of dissipation, comparing the thermal state (the Boltzmann or Gibbs distribution) to its time evolute using relative entropy. The thermal distribution is based on the microcanonical ensemble, whose equal probability assumption is another phrasing of ergodicity in a macroscopic physical context. The puzzle then is why the results of these assumptions are in agreement with experience. We suggest (as others also have) reasons for this limited agreement, but note that the foundations of statistical mechanics make much stronger assumptions, assumptions that do not have the support of either reason or experience. This article is supplemented with comments by P. Gaspard, Y. Pomeau and H. Qian and a final reply by the authors.
Macroscopic Behavior of Nematics with D2d Symmetry
NASA Astrophysics Data System (ADS)
Pleiner, Harald; Brand, Helmut R.
2010-03-01
We discuss the symmetry properties and the macroscopic behavior of a nematic liquid crystal phase with D2d symmetry. Such a phase is a prime candidate for nematic phases made from banana-shaped molecules where the usual quadrupolar order coexists with octupolar (tetrahedratic) order. The resulting nematic phase is non-polar. While this phase could resemble the classic D∞h nematic in the polarizing microscope, it has many static as well as reversible and irreversible properties unknown to non-polar nematics without octupolar order. In particular, there is a linear gradient term in the free energy that selects parity leading to ambidextrously helical ground states when the molecules are achiral. In addition, there are static and irreversible coupling terms of a type only met otherwise in macroscopically chiral liquid crystals, e.g. the ambidextrous analogues of Lehmann-type effects known from cholesteric liquid crystals. Finally, we discuss certain nonlinear aspects of the dynamics related to the non-commutativity of three-dimensional finite rotations as well as other structural nonlinear hydrodynamic effects.
Inverted rank distributions: Macroscopic statistics, universality classes, and critical exponents
NASA Astrophysics Data System (ADS)
Eliazar, Iddo; Cohen, Morrel H.
2014-01-01
An inverted rank distribution is an infinite sequence of positive sizes ordered in a monotone increasing fashion. Interlacing together Lorenzian and oligarchic asymptotic analyses, we establish a macroscopic classification of inverted rank distributions into five “socioeconomic” universality classes: communism, socialism, criticality, feudalism, and absolute monarchy. We further establish that: (i) communism and socialism are analogous to a “disordered phase”, feudalism and absolute monarchy are analogous to an “ordered phase”, and criticality is the “phase transition” between order and disorder; (ii) the universality classes are characterized by two critical exponents, one governing the ordered phase, and the other governing the disordered phase; (iii) communism, criticality, and absolute monarchy are characterized by sharp exponent values, and are inherently deterministic; (iv) socialism is characterized by a continuous exponent range, is inherently stochastic, and is universally governed by continuous power-law statistics; (v) feudalism is characterized by a continuous exponent range, is inherently stochastic, and is universally governed by discrete exponential statistics. The results presented in this paper yield a universal macroscopic socioeconophysical perspective of inverted rank distributions.
Microscopic and macroscopic instabilities in hyperelastic fiber composites
NASA Astrophysics Data System (ADS)
Slesarenko, Viacheslav; Rudykh, Stephan
2017-02-01
In this paper, we study the interplay between macroscopic and microscopic instabilities in 3D periodic fiber reinforced composites undergoing large deformations. We employ the Bloch-Floquet analysis to determine the onset of microscopic instabilities for composites with hyperelastic constituents. We show that the primary mode of buckling in the fiber composites is determined by the volume fraction of fibers and the contrast between elastic moduli of fiber and matrix phases. We find that for composites with volume fraction of fibers exceeding a threshold value, which depends on elastic modulus contrast, the primary buckling mode corresponds to the long wave or macroscopic instability. However, composites with a lower amount of fibers experience microscopic instabilities corresponding to wavy or helical buckling shapes. Buckling modes and critical wavelengths are shown to be highly tunable by material composition. A comparison between the instability behavior of 3D fiber composites and laminates, subjected to uniaxial compression, reveals the significant differences in critical strains, wavelengths, and transition points from macro- to microscopic instabilities in these composites.
Macroscopic Subdivision of Silica Aerogel Collectors for Sample Return Missions
Ishii, H A; Bradley, J P
2005-09-14
Silica aerogel collector tiles have been employed for the collection of particles in low Earth orbit and, more recently, for the capture of cometary particles by NASA's Stardust mission. Reliable, reproducible methods for cutting these and future collector tiles from sample return missions are necessary to maximize the science output from the extremely valuable embedded particles. We present a means of macroscopic subdivision of collector tiles by generating large-scale cuts over several centimeters in silica aerogel with almost no material loss. The cut surfaces are smooth and optically clear allowing visual location of particles for analysis and extraction. This capability is complementary to the smaller-scale cutting capabilities previously described [Westphal (2004), Ishii (2005a, 2005b)] for removing individual impacts and particulate debris in tiny aerogel extractions. Macroscopic cuts enable division and storage or distribution of portions of aerogel tiles for immediate analysis of samples by certain techniques in situ or further extraction of samples suited for other methods of analysis.
Macroscopic, freestanding, and tubular graphene architectures fabricated via thermal annealing.
Nguyen, Duc Dung; Suzuki, Seiya; Kato, Shuji; To, Bao Dong; Hsu, Chia Chen; Murata, Hidekazu; Rokuta, Eiji; Tai, Nyan-Hwa; Yoshimura, Masamichi
2015-03-24
Manipulation of individual graphene sheets/films into specific architectures at macroscopic scales is crucially important for practical uses of graphene. We present herein a versatile and robust method based on annealing of solid carbon precursors on nickel templates and thermo-assisted removal of poly(methyl methacrylate) under low vacuum of ∼0.6 Pa for fabrication of macroscopic, freestanding, and tubular graphene (TG) architectures. Specifically, the TG architectures can be obtained as individual and woven tubes with a diameter of ∼50 μm, a wall thickness in the range of 2.1-2.9 nm, a density of ∼1.53 mg·cm(-3), a thermal stability up to 600 °C in air, an electrical conductivity of ∼1.48 × 10(6) S·m(-1), and field emission current densities on the order of 10(4) A·cm(-2) at low applied electrical fields of 0.6-0.7 V·μm(-1). These properties show great promise for applications in flexible and lightweight electronics, electron guns, or X-ray tube sources.
Traffic dynamics: Its impact on the Macroscopic Fundamental Diagram
NASA Astrophysics Data System (ADS)
Knoop, Victor L.; van Lint, Hans; Hoogendoorn, Serge P.
2015-11-01
Literature shows that-under specific conditions-the Macroscopic Fundamental Diagram (MFD) describes a crisp relationship between the average flow (production) and the average density in an entire network. The limiting condition is that traffic conditions must be homogeneous over the whole network. Recent works describe hysteresis effects: systematic deviations from the MFD as a result of loading and unloading. This article proposes a two dimensional generalization of the MFD, the so-called Generalized Macroscopic Fundamental Diagram (GMFD), which relates the average flow to both the average density and the (spatial) inhomogeneity of density. The most important contribution is that we show this is a continuous function, of which the MFD is a projection. Using the GMFD, we can describe the mentioned hysteresis patterns in the MFD. The underlying traffic phenomenon explaining the two dimensional surface described by the GMFD is that congestion concentrates (and subsequently spreads out) around the bottlenecks that oversaturate first. We call this the nucleation effect. Due to this effect, the network flow is not constant for a fixed number of vehicles as predicted by the MFD, but decreases due to local queueing and spill back processes around the congestion "nuclei". During this build up of congestion, the production hence decreases, which gives the hysteresis effects.
The behavior of a macroscopic granular material in vortex flow
NASA Astrophysics Data System (ADS)
Nishikawa, Asami
A granular material is defined as a collection of discrete particles such as powder and grain. Granular materials display a large number of complex behaviors. In this project, the behavior of macroscopic granular materials under tornado-like vortex airflow, with varying airflow velocity, was observed and studied. The experimental system was composed of a 9.20-cm inner diameter acrylic pipe with a metal mesh bottom holding the particles, a PVC duct, and an airflow source controlled by a variable auto-transformer, and a power-meter. A fixed fan blade was attached to the duct's inner wall to create a tornado-like vortex airflow from straight flow. As the airflow velocity was increased gradually, the behavior of a set of same-diameter granular materials was observed. The observed behaviors were classified into six phases based on the macroscopic mechanical dynamics. Through this project, we gained insights on the significant parameters for a computer simulation of a similar system by Heath Rice [5]. Comparing computationally and experimentally observed phase diagrams, we can see similar structure. The experimental observations showed the effect of initial arrangement of particles on the phase transitions.
NASA Astrophysics Data System (ADS)
Lu, Peizhen
X-ray computed tomography (CT) can characterize internal density gradients. An in-situ laser dilatometry has been constructed to track dimensional change at different positions of a sample during binder removal and sintering. This combination of tools not only allows us to better understand how microscopic change affects macroscopic dimensions, but also provides guidance for a variety of ceramic processes. Non-uniform agglomerate packing and deformation provide density gradients which drive binder migration during binder removal. Simultaneously, density undergoes a slight decrease accompanied by a 1.0% loss in dimensional tolerance. This and CT difference images suggest that capillary forces generated during binder melting can change the density distribution. During sintering, nonuniformities present in the green state persist into the fired state and become exaggerated. Regions of different initial density can occupy different stages sintering. At ˜88% sintered density, CT clearly showed that open porosity follows the distribution of low density areas. Mercury porosimetry detected three distinct levels of porosity. Microstructural examination correlated the porosity level with the coordination of (i) two to three or (ii) multiple grains around pores. Microstructural packing controls both the observed macroscopic expansion at T ≤ 1000°C and the onset of shrinkage. Neck formation initiates during expansion and not exclusively during shrinkage. Inter- and intra-agglomerate expansion/shrinkage proceed simultaneously but the effective 'transmission' of particle-level behavior to the macroscopic level appears to be controlled by the initial agglomerate bonding and internal agglomerate densities. Discrete element modeling provides corroborating evidence regarding the importance of compact continuity. Following the expansion-shrinkage transition, the higher the zone density the faster the initial shrinkage. The 25% RH sample shrank more rapidly than the same zone in
Macroscopic Phase Separation, Modulated Phases, and Microemulsions: A Unified Picture of Rafts
Shlomovitz, Roie; Maibaum, Lutz; Schick, M.
2014-01-01
We simulate a simple phenomenological model describing phase behavior in a multicomponent membrane, a model capable of producing macroscopic phase separation, modulated phases, and microemulsions, all of which have been discussed in terms of raft phenomena. We show that one effect of thermal fluctuations on the mean-field phase diagram is that it permits a direct transition between either one of the coexisting liquid phases to a microemulsion. This implies that one system exhibiting phase separation can be related to a similar system exhibiting the heterogeneities characteristic of a microemulsion. The two systems could differ in their average membrane composition or in the relative compositions of their exoplasmic and cytoplasmic leaves. The model provides a unified description of these raft-associated phenomena. PMID:24806930
Dussi, Simone Dijkstra, Marjolein; Belli, Simone; Roij, René van
2015-02-21
Building a general theoretical framework to describe the microscopic origin of macroscopic chirality in (colloidal) liquid crystals is a long-standing challenge. Here, we combine classical density functional theory with Monte Carlo calculations of virial-type coefficients to obtain the equilibrium cholesteric pitch as a function of thermodynamic state and microscopic details. Applying the theory to hard helices, we observe both right- and left-handed cholesteric phases that depend on a subtle combination of particle geometry and system density. In particular, we find that entropy alone can even lead to a (double) inversion in the cholesteric sense of twist upon changing the packing fraction. We show how the competition between single-particle properties (shape) and thermodynamics (local alignment) dictates the macroscopic chiral behavior. Moreover, by expanding our free-energy functional, we are able to assess, quantitatively, Straley’s theory of weak chirality, which is used in several earlier studies. Furthermore, by extending our theory to different lyotropic and thermotropic liquid-crystal models, we analyze the effect of an additional soft interaction on the chiral behavior of the helices. Finally, we provide some guidelines for the description of more complex chiral phases, like twist-bend nematics. Our results provide new insights into the role of entropy in the microscopic origin of this state of matter.
NASA Astrophysics Data System (ADS)
Babkov, L. M.; Baran, J.; Davydova, N. A.; Drozd, D.; Pyshkin, O. S.; Uspenskiy, K. E.
2008-09-01
The effects of a minor chemical modification such as a change in the position of a Br atom within the same phenyl ring on the optical and macroscopic properties of benzophenone derivatives are investigated by spectroscopic and calorimetry methods. More specifically, we have studied IR and Raman spectra of the two isomers of monosubstituted benzophenones: 2-bromobenzophenone (2BrBP) and 4-bromobenzophenone (4BrBP) in the wide spectral and temperature regions. It has been found that the substitution of a Br in an ortho position leads to some changes of the anharmonicity of the ν(C dbnd O) vibrations. Full geometry optimization and vibrational spectra modeling for 2BrBP and 4BrBP isolated molecules have been calculated by the density functional method (B3LYP/6-31+G(d)) using GAUSSIAN'03 software. Quantum-mechanical calculations for the isolated molecules have shown that the shape of 2BrBP molecule is strongly asymmetric in comparison with the shape of 4BrBP molecule. A change in the molecular shape translates into rather different macroscopic properties such as the crystal melting points. Namely, the melting point of 2BrBP (318 K) was found to be lower than that of 4BrBP isomorphs (358 K). Moreover, 2BrBP exhibits a large reluctance to crystallize, while 4BrBP crystallizes immediately below the melting point as a liquid is cooled.
Gunji, Yukio-Pegio; Shinohara, Shuji; Haruna, Taichi; Basios, Vasileios
2017-02-01
To overcome the dualism between mind and matter and to implement consciousness in science, a physical entity has to be embedded with a measurement process. Although quantum mechanics have been regarded as a candidate for implementing consciousness, nature at its macroscopic level is inconsistent with quantum mechanics. We propose a measurement-oriented inference system comprising Bayesian and inverse Bayesian inferences. While Bayesian inference contracts probability space, the newly defined inverse one relaxes the space. These two inferences allow an agent to make a decision corresponding to an immediate change in their environment. They generate a particular pattern of joint probability for data and hypotheses, comprising multiple diagonal and noisy matrices. This is expressed as a nondistributive orthomodular lattice equivalent to quantum logic. We also show that an orthomodular lattice can reveal information generated by inverse syllogism as well as the solutions to the frame and symbol-grounding problems. Our model is the first to connect macroscopic cognitive processes with the mathematical structure of quantum mechanics with no additional assumptions.
Method to compute wave function evolution from microscopic to macroscopic distances
NASA Astrophysics Data System (ADS)
Sternberg, James
2007-06-01
The treatment of loosely bound and continuum electrons in atomic collisions has provided challenges for calculations of these systems. These challenges have not been fully overcome for ion- atom collisions since electron wave functions evolve from microscopic to macroscopic distances. One major source of difficulty is that solutions to the time-dependent Schr"odinger equation contain an essential singularity at infinity which makes numerical modeling of these systems difficult for large distances. We have identified this essential singularity and developed a method to treat these systems which is extremely efficient and stable. The method is Gallelian invariant, which avoids any ambiguity about what the proper frame of reference should be. It also avoids numerical inaccuracies induced by reflection or absorption at finite boundaries. Wave functions can easily be propagated out to macroscopic distances instead of only approximately 100 au. Finally, the results are consistent with the hidden crossing theory at low impact energies and the Born theory at high energies. In both regimes the electron distribution agree qualitatively with experiment.
Macroscopic quantum entanglement of a Kondo cloud at finite temperature.
Lee, S-S B; Park, Jinhong; Sim, H-S
2015-02-06
We propose a variational approach for computing the macroscopic entanglement in a many-body mixed state, based on entanglement witness operators, and compute the entanglement of formation (EoF), a mixed-state generalization of the entanglement entropy, in single- and two-channel Kondo systems at finite temperature. The thermal suppression of the EoF obeys power-law scaling at low temperature. The scaling exponent is halved from the single- to the two-channel system, which is attributed, using a bosonization method, to the non-Fermi liquid behavior of a Majorana fermion, a "half" of a complex fermion, emerging in the two-channel system. Moreover, the EoF characterizes the size and power-law tail of the Kondo screening cloud of the single-channel system.
Quantum interference in a macroscopic van der Waals conductor
NASA Astrophysics Data System (ADS)
Rischau, C. W.; Wiedmann, S.; Seyfarth, G.; LeBoeuf, D.; Behnia, K.; Fauqué, B.
2017-02-01
Quantum corrections to charge transport can give rise to an oscillatory magnetoconductance, typically observed in mesoscopic samples with a length shorter than or comparable to the phase coherence length. Here, we report the observation of magnetoconductance oscillations periodic in magnetic field with an amplitude of the order of e2/h in macroscopic samples of highly oriented pyrolytic graphite (HOPG). The observed effect emerges when all carriers are confined to their lowest Landau levels. We argue that this quantum interference phenomenon can be explained by invoking moiré superlattices with a discrete distribution in periodicity. According to our results, when the magnetic length ℓB, the Fermi wavelength λF, and the length scale of fluctuations in local chemical potential are comparable in a layered conductor, quantum corrections can be detected over centimetric length scales.
Tunable Broadband Transparency of Macroscopic Quantum Superconducting Metamaterials
NASA Astrophysics Data System (ADS)
Zhang, Daimeng; Trepanier, Melissa; Mukhanov, Oleg; Anlage, Steven M.
2015-10-01
Narrow-band invisibility in an otherwise opaque medium has been achieved by electromagnetically induced transparency (EIT) in atomic systems. The quantum EIT behavior can be classically mimicked by specially engineered metamaterials via carefully controlled interference with a "dark mode." However, the narrow transparency window limits the potential applications that require a tunable wideband transparent performance. Here, we present a macroscopic quantum superconducting metamaterial with manipulative self-induced broadband transparency due to a qualitatively novel nonlinear mechanism that is different from conventional EIT or its classical analogs. A near-complete disappearance of resonant absorption under a range of applied rf flux is observed experimentally and explained theoretically. The transparency comes from the intrinsic bistability of the meta-atoms and can be tuned on and off easily by altering rf and dc magnetic fields, temperature, and history. Hysteretic in situ 100% tunability of transparency paves the way for autocloaking metamaterials, intensity-dependent filters, and fast-tunable power limiters.
Innovating e-waste management: From macroscopic to microscopic scales.
Zeng, Xianlai; Yang, Congren; Chiang, Joseph F; Li, Jinhui
2017-01-01
Waste electrical and electronic equipment (WEEE or e-waste) has become a global problem, due to its potential environmental pollution and human health risk, and its containing valuable resources (e.g., metals, plastics). Recycling for e-waste will be a necessity, not only to address the shortage of mineral resources for electronics industry, but also to decline environmental pollution and human health risk. To systematically solve the e-waste problem, more attention of e-waste management should transfer from macroscopic to microscopic scales. E-waste processing technology should be significantly improved to diminish and even avoid toxic substance entering into downstream of material. The regulation or policy related to new production of hazardous substances in recycled materials should also be carried out on the agenda. All the findings can hopefully improve WEEE legislation for regulated countries and non-regulated countries.
Double-Slit Interference Pattern for a Macroscopic Quantum System
NASA Astrophysics Data System (ADS)
Naeij, Hamid Reza; Shafiee, Afshin
2016-12-01
In this study, we solve analytically the Schrödinger equation for a macroscopic quantum oscillator as a central system coupled to two environmental micro-oscillating particles. Then, the double-slit interference patterns are investigated in two limiting cases, considering the limits of uncertainty in the position probability distribution. Moreover, we analyze the interference patterns based on a recent proposal called stochastic electrodynamics with spin. Our results show that when the quantum character of the macro-system is decreased, the diffraction pattern becomes more similar to a classical one. We also show that, depending on the size of the slits, the predictions of quantum approach could be apparently different with those of the aforementioned stochastic description.
Macroscopic quantum tunnelling in spin filter ferromagnetic Josephson junctions.
Massarotti, D; Pal, A; Rotoli, G; Longobardi, L; Blamire, M G; Tafuri, F
2015-06-09
The interfacial coupling of two materials with different ordered phases, such as a superconductor (S) and a ferromagnet (F), is driving new fundamental physics and innovative applications. For example, the creation of spin-filter Josephson junctions and the demonstration of triplet supercurrents have suggested the potential of a dissipationless version of spintronics based on unconventional superconductivity. Here we demonstrate evidence for active quantum applications of S-F-S junctions, through the observation of macroscopic quantum tunnelling in Josephson junctions with GdN ferromagnetic insulator barriers. We show a clear transition from thermal to quantum regime at a crossover temperature of about 100 mK at zero magnetic field in junctions, which present clear signatures of unconventional superconductivity. Following previous demonstration of passive S-F-S phase shifters in a phase qubit, our result paves the way to the active use of spin filter Josephson systems in quantum hybrid circuits.
Effects of varying interfacial surface tension on macroscopic polymer lenses
NASA Astrophysics Data System (ADS)
Zimmerman, Charlotte; White, Mason; Baylor, Martha-Elizabeth
2015-09-01
We investigate macroscopic polymer lenses (0.5- to 2.5-cm diameter) fabricated by dropping hydrophobic photocurable resin onto the surface of various hydrophilic liquid surfaces. Due to the intermolecular forces along the interface between the two liquids, a lens shape is formed. We find that we can vary the lens geometry by changing the region over which the resin is allowed to spread and the surface tension of the substrate to produce lenses with theoretically determined focal lengths ranging from 5 to 25 mm. These effects are varied by changing the container width, substrate composition, and substrate temperature. We present data for five different variants, demonstrating that we can control the lens dimensions for polymer lens applications that require high surface quality.
Macroscopic quantum tunnelling in spin filter ferromagnetic Josephson junctions
Massarotti, D.; Pal, A.; Rotoli, G.; Longobardi, L.; Blamire, M. G.; Tafuri, F.
2015-01-01
The interfacial coupling of two materials with different ordered phases, such as a superconductor (S) and a ferromagnet (F), is driving new fundamental physics and innovative applications. For example, the creation of spin-filter Josephson junctions and the demonstration of triplet supercurrents have suggested the potential of a dissipationless version of spintronics based on unconventional superconductivity. Here we demonstrate evidence for active quantum applications of S-F-S junctions, through the observation of macroscopic quantum tunnelling in Josephson junctions with GdN ferromagnetic insulator barriers. We show a clear transition from thermal to quantum regime at a crossover temperature of about 100 mK at zero magnetic field in junctions, which present clear signatures of unconventional superconductivity. Following previous demonstration of passive S-F-S phase shifters in a phase qubit, our result paves the way to the active use of spin filter Josephson systems in quantum hybrid circuits. PMID:26054495
Macroscopic electric field inside water-filled biological nanopores.
Acosta Gutiérrez, Silvia; Bodrenko, Igor; Scorciapino, Mariano Andrea; Ceccarelli, Matteo
2016-04-07
Multi-drug resistance bacteria are a challenging problem of contemporary medicine. This is particularly critical for Gram-negative bacteria, where antibiotics are hindered by the outer membrane to reach internal targets. Here more polar antibiotics make use of nanometric water-filled channels to permeate inside. We present in this work a computational all-atom approach, using water as a probe, for the calculation of the macroscopic electric field inside water-filled channels. The method allows one to compare not only different systems but also the same system under different conditions, such as pH and ion concentration. This provides a detailed picture of electrostatics in biological nanopores shedding more light on how the charged residues of proteins determine the electric field inside, and also how medium can tune it. These details are central to unveil the filtering mechanism behind the permeation of small polar molecules through nanometric water-filled channels.
Quantum terahertz electrodynamics and macroscopic quantum tunneling in layered superconductors.
Savel'ev, Sergey; Rakhmanov, A L; Nori, Franco
2007-02-16
We derive a quantum field theory of Josephson plasma waves (JPWs) in layered superconductors, which describes two types of interacting JPW bosonic quanta (one heavy and one lighter). We propose a mechanism of enhancement of macroscopic quantum tunneling (MQT) in stacks of intrinsic Josephson junctions. Because of the long-range interaction between junctions in layered superconductors, the calculated MQT escape rate Gamma has a nonlinear dependence on the number of junctions in the stack. We show that the crossover temperature between quantum and thermal escape increases when increasing the number of junctions. This allows us to quantitatively describe striking recent experiments in Bi2Sr2CaCu2O8+delta stacks.
Macroscopic parameters from simulations of pore scale flow
Blunt, M.; King, P. )
1990-10-15
We simulate two-phase flow in a porous medium, which is represented by random, isotropic two- and three-dimensional networks containing up to 80 000 interconnected pore spaces. The simulations are sufficiently large that macroscopic properties of the flow may be determined. For unstable viscous floods, we show that the displacements are compact with a fractal interface between the fluids. The fractal dimension is found as a function of viscosity ratio. For invasion percolation, where the displacement is controlled by capillary forces, and for viscous fingering, we calculate relative permeabilities in an averaged two-phase Darcy equation, which we show are functions of mean saturation. The relative permeabilities also depend on flow rate, which means that the two-phase Darcy equation is nonlinear, even with microscopic linear Poiseuille flow.
Macroscopic self-reorientation of interacting two-dimensional crystals
Woods, C. R.; Withers, F.; Zhu, M. J.; Cao, Y.; Yu, G.; Kozikov, A.; Ben Shalom, M.; Morozov, S. V.; van Wijk, M. M.; Fasolino, A.; Katsnelson, M. I.; Watanabe, K.; Taniguchi, T.; Geim, A. K.; Mishchenko, A.; Novoselov, K. S.
2016-01-01
Microelectromechanical systems, which can be moved or rotated with nanometre precision, already find applications in such fields as radio-frequency electronics, micro-attenuators, sensors and many others. Especially interesting are those which allow fine control over the motion on the atomic scale because of self-alignment mechanisms and forces acting on the atomic level. Such machines can produce well-controlled movements as a reaction to small changes of the external parameters. Here we demonstrate that, for the system of graphene on hexagonal boron nitride, the interplay between the van der Waals and elastic energies results in graphene mechanically self-rotating towards the hexagonal boron nitride crystallographic directions. Such rotation is macroscopic (for graphene flakes of tens of micrometres the tangential movement can be on hundreds of nanometres) and can be used for reproducible manufacturing of aligned van der Waals heterostructures. PMID:26960435
Macroscopic and direct light propulsion of bulk graphene material
NASA Astrophysics Data System (ADS)
Zhang, Tengfei; Chang, Huicong; Wu, Yingpeng; Xiao, Peishuang; Yi, Ningbo; Lu, Yanhong; Ma, Yanfeng; Huang, Yi; Zhao, Kai; Yan, Xiao-Qing; Liu, Zhi-Bo; Tian, Jian-Guo; Chen, Yongsheng
2015-07-01
It has been a great challenge to achieve the direct light manipulation of matter on a bulk scale. In this work the direct light propulsion of matter is observed on a macroscopic scale using a bulk graphene-based material. The unique structure and properties of graphene, and the novel morphology of the bulk three-dimensional linked graphene material make it capable not only of absorbing light at various wavelengths but also of emitting energetic electrons efficiently enough to drive the bulk material, following Newtonian mechanics. Thus, the unique photonic and electronic properties of individual graphene sheets are manifested in the response of the bulk state. These results offer an exciting opportunity to bring about bulk-scale light manipulation with the potential to realize long-sought applications in areas such as the solar sail and space transportation driven directly by sunlight.
Celestial bodies macroscopic movement is due to the radiation
NASA Astrophysics Data System (ADS)
Yongquan, Han
2016-03-01
The star is radiate, also as the planet. In fact, all the real objects are radiate, but the strength of the radiation is different. Radiation will reduce the quality of the object, but time is not long enough to reduce the mass of the subject, so it is difficult for us to observe. Due to the large object lifecycle, to study the changing rule of the object, we must consider the radiation on the quality of the celestial bodies, and the outer space radiate particles' motion, also consider objects interact with objects of radiation. The reason Celestial bodies moves is that the radiation of those Celestial bodies Interact with each other, Celestial bodies macroscopic movement is due to the radiation. The earth's rotation and revolution is a measure of the survive ability. Author: hanyongquan TEL: 15611860790
Macroscopic Characteristics of Unsteady Granular Flows in Rotating Tumblers
NASA Astrophysics Data System (ADS)
Paprocki, Daniel; Pohlman, Nicholas
2010-11-01
Flow of silicate beads in rotating tumblers of triangular cross-sections are explored with respect to transient response of macroscopic properties. High-speed digital images are synchronized to tumbler orientation through an in-line rotary encoder. Image processing toolboxes are utilized to generate quantitative data for analysis. Time-dependent properties of free surface length, flowing layer curvature, and dynamic angle of repose are reported. The correlation of these properties with the orientation exhibits a phase difference that is a function of tumbler dimensions and fill fraction. Concurrent measurements of input energy to the system may lead to control algorithms to generate steady flow in inherently unsteady systems that would improve efficiency of granular transport methods.
Photoacoustic brain imaging: from microscopic to macroscopic scales
Yao, Junjie; Wang, Lihong V.
2014-01-01
Abstract. Human brain mapping has become one of the most exciting contemporary research areas, with major breakthroughs expected in the coming decades. Modern brain imaging techniques have allowed neuroscientists to gather a wealth of anatomic and functional information about the brain. Among these techniques, by virtue of its rich optical absorption contrast, high spatial and temporal resolutions, and deep penetration, photoacoustic tomography (PAT) has attracted more and more attention, and is playing an increasingly important role in brain studies. In particular, PAT complements other brain imaging modalities by providing high-resolution functional and metabolic imaging. More importantly, PAT’s unique scalability enables scrutinizing the brain at both microscopic and macroscopic scales, using the same imaging contrast. In this review, we present the state-of-the-art PAT techniques for brain imaging, summarize representative neuroscience applications, outline the technical challenges in translating PAT to human brain imaging, and envision potential technological deliverables. PMID:25401121
Elastic enhancement factor: From mesoscopic systems to macroscopic analogous devices
NASA Astrophysics Data System (ADS)
Sokolov, Valentin V.; Zhirov, Oleg V.
2015-05-01
Excess of probabilities of elastic processes over inelastic ones is a characteristic feature of the chaotic resonance scattering predicted by the random matrix theory (RMT). Quantitatively, this phenomenon is characterized by the elastic enhancement factor F(β ) that is, essentially, a typical ratio of elastic and inelastic cross sections. Being measured experimentally, this quantity can provide important information on the character of dynamics of the complicated intermediate open system formed on the intermediate stage of various resonance scattering processes. We discuss properties of the enhancement factor in a wide scope from mesoscopoic systems as, for example, heavy nuclei to macroscopic electromagnetic analogous devices imitating two-dimensional quantum billiards. We demonstrate a substantial qualitative distinction between the elastic enhancement factor's peculiarities in these two cases. A complete analytical solution is found for the case of systems without time-reversal symmetry and only a few equivalent open scattering channels.
Toroidal dipolar excitation and macroscopic electromagnetic properties of metamaterials
NASA Astrophysics Data System (ADS)
Savinov, V.; Fedotov, V. A.; Zheludev, N. I.
2014-05-01
The toroidal dipole is a peculiar electromagnetic excitation that can not be presented in terms of standard electric and magnetic multipoles. A static toroidal dipole has been shown to lead to violation of parity in atomic spectra and many other unusual electromagnetic phenomena. The existence of electromagnetic resonances of toroidal nature was experimentally demonstrated only recently, first in the microwave metamaterials, and then at optical frequencies, where they could be important in spectroscopy analysis of a wide class of media with constituents of toroidal symmetry, such as complex organic molecules, fullerenes, bacteriophages, etc. Despite the experimental progress in studying toroidal resonances, no direct link has yet been established between microscopic toroidal excitations and macroscopic scattering characteristics of the medium. To address this essential gap in the electromagnetic theory, we have developed an analytical approach for calculating the transmissivity and reflectivity of thin slabs of materials that exhibit toroidal dipolar excitations.
Imparting large macroscopic changes with small changes in polypeptide composition
NASA Astrophysics Data System (ADS)
Sing, Michelle; McKinley, Gareth; Olsen, Bradley
Block copolymers composed of polypeptides provide an excellent platform for exploring the underlying physics surrounding macroscopic associative network behavior. Previous work in our group has elucidated a difference in the mechanical properties of two nearly identical elastin-like polypeptide (ELP) endblocks. In poly(ELP)s, this substitution is known to result in tighter beta turns. These beta turns exhibit slower responses to changes in temperature within the material. Under shear, the modulus for the alanine-containing ELP triblock is almost three times higher than the glycine-containing ELP. Additionally, preliminary tensile tests show higher stress and strain at break for the alanine ELP triblock. We are able to explain the reasons for this behavior using a variety of spectroscopic and analytical techniques. Small angle neutron and x-ray scattering indicate differences in ordering between the alanine and glycine containing ELP materials both in shear and in stagnant flow.
Exact Solution to Integrable Open Multi-species SSEP and Macroscopic Fluctuation Theory
NASA Astrophysics Data System (ADS)
Vanicat, M.
2017-01-01
We introduce a multi-species generalization of the symmetric simple exclusion process with open boundaries. This model possesses the property of being integrable and appears as physically relevant because the boundary conditions can be interpreted as the interaction with particles reservoirs with fixed densities of each species. The system is driven out-of-equilibrium by these reservoirs. The steady state is analytically computed in a matrix product form. This algebraic structure allows us to obtain exact expressions for the mean particle currents and for the one and two-point correlation functions. An additivity principle is also derived from the matrix ansatz and permits the computation of the large deviation functional of the density profile. We also propose a description of the model in the context of the macroscopic fluctuation theory and we check the consistency with the exact computations from the finite size lattice.
Exact Solution to Integrable Open Multi-species SSEP and Macroscopic Fluctuation Theory
NASA Astrophysics Data System (ADS)
Vanicat, M.
2017-03-01
We introduce a multi-species generalization of the symmetric simple exclusion process with open boundaries. This model possesses the property of being integrable and appears as physically relevant because the boundary conditions can be interpreted as the interaction with particles reservoirs with fixed densities of each species. The system is driven out-of-equilibrium by these reservoirs. The steady state is analytically computed in a matrix product form. This algebraic structure allows us to obtain exact expressions for the mean particle currents and for the one and two-point correlation functions. An additivity principle is also derived from the matrix ansatz and permits the computation of the large deviation functional of the density profile. We also propose a description of the model in the context of the macroscopic fluctuation theory and we check the consistency with the exact computations from the finite size lattice.
Majumdar, A.; Alencar, A. M.; Buldyrev, S. V.; Hantos, Z.; Stanley, H. E.; Suki, B.
2001-07-30
We analyze the problem of fluid flow in a bifurcating structure containing random blockages that can be removed by fluid pressure. We introduce an asymmetric tree model and find that the predicted pressure-volume relation is connected to the distribution {Pi}(n) of the generation number n of the tree's terminal segments. We use this relation to explore the branching structure of the lung by analyzing experimental pressure-volume data from dog lungs. The {Pi}(n) extracted from the data using the model agrees well with experimental data on the branching structure. We can thus obtain information about the asymmetric structure of the lung from macroscopic, noninvasive pressure-volume measurements.
Macroscopic behavior of a bar undergoing the paraelectric-ferroelectric phase transformation
NASA Astrophysics Data System (ADS)
Jiang, Qing
1993-10-01
R ECENT WORK of the author has developed a continuum model for the paraelectric—ferroelectric phase transformation. The present paper describes the detailed implications of this model when it has been supplemented with constitutive information pertaining to the phase transformation. An explicit Helmholtz potential has been constructed to characterize a hypothetical crystal capable of undergoing the paraelectric-ferroelectric phase transformation under the influence of applied electric fields or thermomechanical loads. The hysteretic macroscopic behavior associated with the phase transformation, induced by variation of temperature, application of electric fields and mechanical loads, has been studied. Some of the predictions have been compared qualitatively with experimental observations. The entire analysis is carried out within a one-dimensional setting.
NASA Technical Reports Server (NTRS)
Mauk, B. H.
1989-01-01
The 'convection surge' model for ion acceleration, designed by Mauk (1986) to explain the observed ion distributions and the field-aligned character of middle magnetospheric ion distributions during the expansion phase of a substorm, was extended to include the self-consistent generation of magnetic-field-aligned electric fields. Results from the modified model show that the convection surge mechanism leads to the generation of dynamical macroscopic magnetic field-aligned electric fields that begin their strongest developments very near the magnetic equator and then propagate to higher latitudes. Potential drops as high as 1 to 10 kV might be expected, depending on the mass species of the ions and on the electron temperatures. It is speculated that the convection surge mechanism could be a key player in the transient field-aligned electromagnetic processes observed to operate within the middle magnetosphere.
Macroscopic electrical propagation in the guinea pig urinary bladder.
Hammad, F T; Stephen, B; Lubbad, L; Morrison, J F B; Lammers, W J
2014-07-15
There is little knowledge about macroscopic electrical propagation in the wall of the urinary bladder. Recording simultaneously from a large number of extracellular electrodes is one technology that could be used to study the patterns of macroscopic electrical propagations. The urinary bladders from 14 guinea pigs were isolated and placed in an organ bath. A 16 × 4-electrode array was positioned at various sites on the serosal bladder surface, and recordings were performed at different intravesical volumes. In four experiments, carbachol (CCH; 10(-6) M), nifedipine (10 mM), or tetrodotoxin (TTX; 10(-6) M) was added to the superfusing fluid. After the experiments, the extracellular signals were analyzed and propagation maps were constructed. Electrical waves were detected at all sites on the bladder surface and propagated for a limited distance before terminating spontaneously. The majority of waves (>90%) propagated in the axial direction (i.e., from dome to base or vice versa). An increase in vesicle volume significantly decreased the conduction velocity (from 4.9 ± 1.5 to 2.7 ± 0.7 cm/s; P < 0.05). CCH increased, nifedipine decreased, while TTX had little effect on electrical activities. In addition, a new electrical phenomenon, termed a "patch," was discovered whereby a simultaneous electrical deflection was detected across an area of the bladder surface. Two types of electrical activities were detected on the bladder surface: 1) electrical waves propagating preferentially in the axial direction and 2) electrical patches. The propagating electrical waves could form the basis for local spontaneous contractions in the bladder during the filling phase.
De Ryck, L; Lauriks, W; Leclaire, P; Groby, J P; Wirgin, A; Depollier, C
2008-09-01
The present paper deals with the inverse scattering problem involving macroscopically inhomogeneous rigid frame porous media. It consists of the recovery, from acoustic measurements, of the profiles of spatially varying material parameters by means of an optimization approach. The resolution is based on the modeling of acoustic wave propagation in macroscopically inhomogeneous rigid frame porous materials, which was recently derived from the generalized Biot's theory. In practice, the inverse problem is solved by minimizing an objective function defined in the least-square sense by the comparison of the calculated reflection (and transmission) coefficient(s) with the measured or synthetic one(s), affected or not by additive Gaussian noise. From an initial guess, the profiles of the x-dependent material parameters are reconstructed iteratively with the help of a standard conjugate gradient method. The convergence rate of the latter and the accuracy of the reconstructions are improved by the availability of an analytical gradient.
NASA Astrophysics Data System (ADS)
Harti, Ralph P.; Strobl, Markus; Betz, Benedikt; Jefimovs, Konstantins; Kagias, Matias; Grünzweig, Christian
2017-03-01
Neutron imaging and scattering give data of significantly different nature and traditional methods leave a gap of accessible structure sizes at around 10 micrometers. Only in recent years overlap in the probed size ranges could be achieved by independent application of high resolution scattering and imaging methods, however without providing full structural information when microstructures vary on a macroscopic scale. In this study we show how quantitative neutron dark-field imaging with a novel experimental approach provides both sub-pixel resolution with respect to microscopic correlation lengths and imaging of macroscopic variations of the microstructure. Thus it provides combined information on multiple length scales. A dispersion of micrometer sized polystyrene colloids was chosen as a model system to study gravity induced crystallisation of microspheres on a macro scale, including the identification of ordered as well as unordered phases. Our results pave the way to study heterogeneous systems locally in a previously impossible manner.
Harti, Ralph P.; Strobl, Markus; Betz, Benedikt; Jefimovs, Konstantins; Kagias, Matias; Grünzweig, Christian
2017-01-01
Neutron imaging and scattering give data of significantly different nature and traditional methods leave a gap of accessible structure sizes at around 10 micrometers. Only in recent years overlap in the probed size ranges could be achieved by independent application of high resolution scattering and imaging methods, however without providing full structural information when microstructures vary on a macroscopic scale. In this study we show how quantitative neutron dark-field imaging with a novel experimental approach provides both sub-pixel resolution with respect to microscopic correlation lengths and imaging of macroscopic variations of the microstructure. Thus it provides combined information on multiple length scales. A dispersion of micrometer sized polystyrene colloids was chosen as a model system to study gravity induced crystallisation of microspheres on a macro scale, including the identification of ordered as well as unordered phases. Our results pave the way to study heterogeneous systems locally in a previously impossible manner. PMID:28303923
Kim, Y I; Salomon, R N; Graeme-Cook, F; Choi, S W; Smith, D E; Dallal, G E; Mason, J B
1996-01-01
BACKGROUND AND AIMS: Diminished folate status is associated with enhanced colorectal carcinogenesis. This study investigated the potential chemopreventive role of dietary folate in the dimethylhydrazine colorectal cancer model. SUBJECTS AND METHODS: Sprague-Dawley rats were fed diets containing either 0, 2 (daily dietary requirement), 8 or 40 mg folate/kg diet for 20 weeks. After five weeks of diet, rats were injected with dimethyl-hydrazine (44 mg/kg) weekly for 15 weeks. Fifteen weeks after the first injection of dimethylhydrazine, all rats were killed. Folate status was determined, and the entire colorectum from each rat was analysed for macroscopic and microscopic neoplasms. RESULTS: Plasma and colonic folate concentrations correlated directly with dietary folate levels (p < 0.005). The incidence of microscopic neoplasms was similar among the four groups. However, the incidence and the average number of macroscopic tumours per rat decreased progressively with increasing dietary folate levels up to 8 mg/kg diet (p < 0.05). In the strongly procarcinogenic milieu used in this study, folate supplementation at 20 times the basal requirement was associated with rates of macroscopic tumour development that were intermediate, and not statistically distinct, from rates observed at either 0 or 8 mg/kg diet. CONCLUSIONS: These data indicate that in this rat model, (a) increasing dietary folate up to four times the basal requirement leads to a progressive reduction in the evolution of macroscopic neoplasms from microscopic foci; and (b) folate supplementation beyond four times the requirement does not convey further benefit. PMID:9014775
Klymko, Katherine; Geissler, Phillip L; Whitelam, Stephen
2016-08-01
Colloidal particles of two types, driven in opposite directions, can segregate into lanes [Vissers et al., Soft Matter 7, 2352 (2011)1744-683X10.1039/c0sm01343a]. This phenomenon can be reproduced by two-dimensional Brownian dynamics simulations of model particles [Dzubiella et al., Phys. Rev. E 65, 021402 (2002)1063-651X10.1103/PhysRevE.65.021402]. Here we use computer simulation to assess the generality of lane formation with respect to variation of particle type and dynamical protocol. We find that laning results from rectification of diffusion on the scale of a particle diameter: oppositely driven particles must, in the time taken to encounter each other in the direction of the drive, diffuse in the perpendicular direction by about one particle diameter. This geometric constraint implies that the diffusion constant of a particle, in the presence of those of the opposite type, grows approximately linearly with the Péclet number, a prediction confirmed by our numerics over a range of model parameters. Such environment-dependent diffusion is statistically similar to an effective interparticle attraction; consistent with this observation, we find that oppositely driven nonattractive colloids display features characteristic of the simplest model system possessing both interparticle attractions and persistent motion, the driven Ising lattice gas [Katz, Leibowitz, and Spohn, J. Stat. Phys. 34, 497 (1984)JSTPBS0022-471510.1007/BF01018556]. These features include long-ranged correlations in the disordered regime, a critical regime characterized by a change in slope of the particle current with the Péclet number, and fluctuations that grow with system size. By analogy, we suggest that lane formation in the driven colloid system is a phase transition in the macroscopic limit, but that macroscopic phase separation would not occur in finite time upon starting from disordered initial conditions.
NASA Astrophysics Data System (ADS)
Siboni, Morteza H.; Ponte Castañeda, Pedro
2016-06-01
Particle-reinforced rubbers are composite materials consisting of randomly distributed, stiff fibers/particles in a soft elastomeric material. Since the particles are stiff compared to the embedding rubber, their deformation can be ignored for all practical purposes. However, due to the softness of the rubber, they can undergo rigid body translations and rotations. Constitutive models accounting for the effect of such particle motions on the macroscopic response under prescribed deformations on the boundary have been developed recently. But, in some applications (e.g., magneto-active elastomers), the particles may experience additional torques as a consequence of an externally applied (magnetic) field, which, in turn, can affect the overall rotation of the particles in the rubber, and therefore also the macroscopic response of the composite. This paper is concerned with the development of constitutive models for particle-reinforced elastomers, which are designed to account for externally applied torques on the internally distributed particles, in addition to the externally applied deformation on the boundary of the composite. For this purpose, we propose a new variational framework involving suitably prescribed eigenstresses on the particles. For simplicity, the framework is applied to an elastomer reinforced by aligned, rigid, cylindrical fibers of elliptical cross section, which can undergo finite rotations in the context of a finite-deformation, plane strain problem for the composite. In particular, expressions are derived for the average in-plane rotation of the fibers as a function of the torques that are applied on them, both under vanishing and prescribed strain on the boundary. The results of this work will make possible the development of improved constitutive models for magneto-active elastomers, and other types of smart composite materials that are susceptible to externally applied torques.
A Poisson Random Field Framework Bridges Micro- To Macroscopic Scales In Microbial Transport
NASA Astrophysics Data System (ADS)
Yeghiazarian, L.; Safwat, A.; Shuster, W.; Samorodnitsky, G.; Whiteaker, T. L.; Maidment, D. R.
2014-12-01
Understanding microbial fate and transport in surface water and making accurate predictions is a formidable task. Evidence from experimental and observational studies unequivocally points to temporal and spatial variability in microbial distributions with significant correlation structure; and to the critical role of processes at the microscopic level. The temporal and spatial variability in microbial distributions arises from inherently random environmental factors and processes. Many cannot be described accurately using deterministic methods, necessitating a stochastic approach to microbial modeling. At the same time, microbial tracking studies identified significant spatial and temporal correlations in microbial distributions in streams, and highlighted the necessity of including microbial interactions with sediments, settling and re-suspension in models of microbial transport. Such understanding must be gained from microscopic, particle-scale research, because microdynamic interactions ultimately give rise to phenomena on higher scales. The challenge then is to be able to describe microbial behavior in probabilistic terms to take care of random drivers, while incorporating processes on microscopic scale and bridging the gap to macroscopic entities like concentrations that are used in watershed management. We have derived a stochastic modeling paradigm that bridges microscopic processes to macroscopic manifestation of microbial behavior in time and space, where the Markov behavior of individual microbes collectively translates into a non-homogeneous Poisson random field that describes microbial population dynamics. The Poisson framework is applied to a mixed-use watershed and implemented within ArcGIS, which makes a wealth of geographic, topologic, soil and other information, as well as data from national and regional datasets, instantly available. Probabilities of exceeding microbial safety thresholds are then obtained at any point in time and space in the
NASA Astrophysics Data System (ADS)
Klymko, Katherine; Geissler, Phillip L.; Whitelam, Stephen
2016-08-01
Colloidal particles of two types, driven in opposite directions, can segregate into lanes [Vissers et al., Soft Matter 7, 2352 (2011), 10.1039/c0sm01343a]. This phenomenon can be reproduced by two-dimensional Brownian dynamics simulations of model particles [Dzubiella et al., Phys. Rev. E 65, 021402 (2002), 10.1103/PhysRevE.65.021402]. Here we use computer simulation to assess the generality of lane formation with respect to variation of particle type and dynamical protocol. We find that laning results from rectification of diffusion on the scale of a particle diameter: oppositely driven particles must, in the time taken to encounter each other in the direction of the drive, diffuse in the perpendicular direction by about one particle diameter. This geometric constraint implies that the diffusion constant of a particle, in the presence of those of the opposite type, grows approximately linearly with the Péclet number, a prediction confirmed by our numerics over a range of model parameters. Such environment-dependent diffusion is statistically similar to an effective interparticle attraction; consistent with this observation, we find that oppositely driven nonattractive colloids display features characteristic of the simplest model system possessing both interparticle attractions and persistent motion, the driven Ising lattice gas [Katz, Leibowitz, and Spohn, J. Stat. Phys. 34, 497 (1984), 10.1007/BF01018556]. These features include long-ranged correlations in the disordered regime, a critical regime characterized by a change in slope of the particle current with the Péclet number, and fluctuations that grow with system size. By analogy, we suggest that lane formation in the driven colloid system is a phase transition in the macroscopic limit, but that macroscopic phase separation would not occur in finite time upon starting from disordered initial conditions.
Approximate Inference for Time-Varying Interactions and Macroscopic Dynamics of Neural Populations
Obermayer, Klaus
2017-01-01
The models in statistical physics such as an Ising model offer a convenient way to characterize stationary activity of neural populations. Such stationary activity of neurons may be expected for recordings from in vitro slices or anesthetized animals. However, modeling activity of cortical circuitries of awake animals has been more challenging because both spike-rates and interactions can change according to sensory stimulation, behavior, or an internal state of the brain. Previous approaches modeling the dynamics of neural interactions suffer from computational cost; therefore, its application was limited to only a dozen neurons. Here by introducing multiple analytic approximation methods to a state-space model of neural population activity, we make it possible to estimate dynamic pairwise interactions of up to 60 neurons. More specifically, we applied the pseudolikelihood approximation to the state-space model, and combined it with the Bethe or TAP mean-field approximation to make the sequential Bayesian estimation of the model parameters possible. The large-scale analysis allows us to investigate dynamics of macroscopic properties of neural circuitries underlying stimulus processing and behavior. We show that the model accurately estimates dynamics of network properties such as sparseness, entropy, and heat capacity by simulated data, and demonstrate utilities of these measures by analyzing activity of monkey V4 neurons as well as a simulated balanced network of spiking neurons. PMID:28095421
Spontaneous assembly of a self-complementary oligopeptide to form a stable macroscopic membrane
NASA Technical Reports Server (NTRS)
Zhang, S.; Holmes, T.; Lockshin, C.; Rich, A.
1993-01-01
A 16-residue peptide [(Ala-Glu-Ala-Glu-Ala-Lys-Ala-Lys)2] has a characteristic beta-sheet circular dichroism spectrum in water. Upon the addition of salt, the peptide spontaneously assembles to form a macroscopic membrane. The membrane does not dissolve in heat or in acidic or alkaline solutions, nor does it dissolve upon addition of guanidine hydrochloride, SDS/urea, or a variety of proteolytic enzymes. Scanning EM reveals a network of interwoven filaments approximately 10-20 nm in diameter. An important component of the stability is probably due to formation of complementary ionic bonds between glutamic and lysine side chains. This phenomenon may be a model for studying the insoluble peptides found in certain neurological disorders. It may also have implications for biomaterials and origin-of-life research.
pH-responsive self-assembly by molecular recognition on a macroscopic scale.
Zheng, Yongtai; Hashidzume, Akihito; Harada, Akira
2013-07-12
Macroscopic pH-responsive self-assembly is successfully constructed by polyacrylamide(pAAm)-based gels carrying dansyl (Dns) and β-cyclodextrin (βCD) residues, which are represented as Dns-gel and βCD-gel, respectively. Dns-gel and βCD-gel assemble together at pH ≥ 4.0, but disassemble at pH ≤ 3.0. The adhesion strengths for pairs of Dns-gel/βCD-gel increase with increasing pH. The fluorescence study on the model system of pAAm modified with 1 mol% Dns moieties (pAAm/Dns) reveals that Dns residues are protonated at a lower pH, which results in the reduction in binding constant (K) for Dns residues and βCD.
Hao, Qing-Yi; Jiang, Rui; Hu, Mao-Bin; Jia, Bin; Wang, Wen-Xu
2016-01-01
Driven diffusive systems have been a paradigm for modelling many physical, chemical, and biological transport processes. In the systems, spatial correlation plays an important role in the emergence of a variety of nonequilibrium phenomena and exhibits rich features such as pronounced oscillations. However, the lack of analytical results of spatial correlation precludes us from fully understanding the effect of spatial correlation on the dynamics of the system. Here we offer precise analytical predictions of the spatial correlation in a typical driven diffusive system, namely facilitated asymmetric exclusion process. We find theoretically that the correlation between two sites decays exponentially as their distance increases, which is in good agreement with numerical simulations. Furthermore, we find the exponential decay is a universal property of macroscopic homogeneous state in a broad class of 1D driven diffusive systems. Our findings deepen the understanding of many nonequilibrium phenomena resulting from spatial correlation in driven diffusive systems. PMID:26804770
Generation of macroscopic Schrödinger cat state in diamond mechanical resonator.
Hou, Qizhe; Yang, Wanli; Chen, Changyong; Yin, Zhangqi
2016-11-23
We propose a scheme to generate macroscopic Schrödinger cat state (SCS) in diamond mechanical resonator (DMR) via the dynamical strain-mediated coupling mechanism. In our model, the direct coupling between the nitrogen-vacancy (NV) center and lattice strain field enables coherent spin-phonon interactions in the quantum regime. Based on a cyclic Δ-type transition structure of the NV center constructed by combining the quantized mechanical strain field and a pair of external microwave fields, the populations of the different energy levels can be selectively transferred by controlling microwave fields, and the SCS can be created by adjusting the controllable parameters of the system. Furthermore, we demonstrate the nonclassicality of the mechanical SCS both in non-dissipative case and dissipative case. The experimental feasibility and challenge are justified using currently available technology.
Generation of macroscopic Schrödinger cat state in diamond mechanical resonator
Hou, Qizhe; Yang, Wanli; Chen, Changyong; Yin, Zhangqi
2016-01-01
We propose a scheme to generate macroscopic Schrödinger cat state (SCS) in diamond mechanical resonator (DMR) via the dynamical strain-mediated coupling mechanism. In our model, the direct coupling between the nitrogen-vacancy (NV) center and lattice strain field enables coherent spin–phonon interactions in the quantum regime. Based on a cyclic Δ-type transition structure of the NV center constructed by combining the quantized mechanical strain field and a pair of external microwave fields, the populations of the different energy levels can be selectively transferred by controlling microwave fields, and the SCS can be created by adjusting the controllable parameters of the system. Furthermore, we demonstrate the nonclassicality of the mechanical SCS both in non-dissipative case and dissipative case. The experimental feasibility and challenge are justified using currently available technology. PMID:27876846
Spontaneous assembly of a self-complementary oligopeptide to form a stable macroscopic membrane.
Zhang, S; Holmes, T; Lockshin, C; Rich, A
1993-01-01
A 16-residue peptide [(Ala-Glu-Ala-Glu-Ala-Lys-Ala-Lys)2] has a characteristic beta-sheet circular dichroism spectrum in water. Upon the addition of salt, the peptide spontaneously assembles to form a macroscopic membrane. The membrane does not dissolve in heat or in acidic or alkaline solutions, nor does it dissolve upon addition of guanidine hydrochloride, SDS/urea, or a variety of proteolytic enzymes. Scanning EM reveals a network of interwoven filaments approximately 10-20 nm in diameter. An important component of the stability is probably due to formation of complementary ionic bonds between glutamic and lysine side chains. This phenomenon may be a model for studying the insoluble peptides found in certain neurological disorders. It may also have implications for biomaterials and origin-of-life research. Images Fig. 2 Fig. 3 PMID:7682699
Hao, Qing-Yi; Jiang, Rui; Hu, Mao-Bin; Jia, Bin; Wang, Wen-Xu
2016-01-25
Driven diffusive systems have been a paradigm for modelling many physical, chemical, and biological transport processes. In the systems, spatial correlation plays an important role in the emergence of a variety of nonequilibrium phenomena and exhibits rich features such as pronounced oscillations. However, the lack of analytical results of spatial correlation precludes us from fully understanding the effect of spatial correlation on the dynamics of the system. Here we offer precise analytical predictions of the spatial correlation in a typical driven diffusive system, namely facilitated asymmetric exclusion process. We find theoretically that the correlation between two sites decays exponentially as their distance increases, which is in good agreement with numerical simulations. Furthermore, we find the exponential decay is a universal property of macroscopic homogeneous state in a broad class of 1D driven diffusive systems. Our findings deepen the understanding of many nonequilibrium phenomena resulting from spatial correlation in driven diffusive systems.
Spontaneous assembly of a self-complementary oligopeptide to form a stable macroscopic membrane.
Zhang, S; Holmes, T; Lockshin, C; Rich, A
1993-04-15
A 16-residue peptide [(Ala-Glu-Ala-Glu-Ala-Lys-Ala-Lys)2] has a characteristic beta-sheet circular dichroism spectrum in water. Upon the addition of salt, the peptide spontaneously assembles to form a macroscopic membrane. The membrane does not dissolve in heat or in acidic or alkaline solutions, nor does it dissolve upon addition of guanidine hydrochloride, SDS/urea, or a variety of proteolytic enzymes. Scanning EM reveals a network of interwoven filaments approximately 10-20 nm in diameter. An important component of the stability is probably due to formation of complementary ionic bonds between glutamic and lysine side chains. This phenomenon may be a model for studying the insoluble peptides found in certain neurological disorders. It may also have implications for biomaterials and origin-of-life research.
Introduction to macroscopic power scaling principles for high-order harmonic generation
NASA Astrophysics Data System (ADS)
Heyl, C. M.; Arnold, C. L.; Couairon, A.; L'Huillier, A.
2017-01-01
This tutorial presents an introduction to power scaling concepts for high-order harmonic generation (HHG) and attosecond pulse production. We present an overview of state-of-the-art HHG-based extreme ultraviolet (XUV) sources, followed by a brief introduction to basic principles underlying HHG and a detailed discussion of macroscopic effects and scaling principles. Particular emphasis is put on a general scaling model that allows the invariant scaling of the HHG process both, to μJ-level driving laser pulses and thus to multi-MHz repetition rates as well as to 100 mJ-or even Joule-level laser pulses, allowing new intensity regimes with attosecond XUV pulses.
Generation of macroscopic Schrödinger cat state in diamond mechanical resonator
NASA Astrophysics Data System (ADS)
Hou, Qizhe; Yang, Wanli; Chen, Changyong; Yin, Zhangqi
2016-11-01
We propose a scheme to generate macroscopic Schrödinger cat state (SCS) in diamond mechanical resonator (DMR) via the dynamical strain-mediated coupling mechanism. In our model, the direct coupling between the nitrogen-vacancy (NV) center and lattice strain field enables coherent spin–phonon interactions in the quantum regime. Based on a cyclic Δ-type transition structure of the NV center constructed by combining the quantized mechanical strain field and a pair of external microwave fields, the populations of the different energy levels can be selectively transferred by controlling microwave fields, and the SCS can be created by adjusting the controllable parameters of the system. Furthermore, we demonstrate the nonclassicality of the mechanical SCS both in non-dissipative case and dissipative case. The experimental feasibility and challenge are justified using currently available technology.
Quantum-limited heat conduction over macroscopic distances.
Partanen, Matti; Tan, Kuan Yen; Govenius, Joonas; Lake, Russell E; Mäkelä, Miika K; Tanttu, Tuomo; Möttönen, Mikko
2016-05-01
The emerging quantum technological apparatuses1, 2, such as the quantum computer3-6, call for extreme performance in thermal engineering7. Cold distant heat sinks are needed for the quantized electric degrees of freedom due to the increasing packaging density and heat dissipation. Importantly, quantum mechanics sets a fundamental upper limit for the flow of information and heat, which is quantified by the quantum of thermal conductance8-10. However, the short distance between the heat-exchanging bodies in the previous experiments11-14 hinders their applicability in quantum technology. Here, we present experimental observations of quantum-limited heat conduction over macroscopic distances extending to a metre. We achieved this improvement of four orders of magnitude in the distance by utilizing microwave photons travelling in superconducting transmission lines. Thus, it seems that quantum-limited heat conduction has no fundamental distance cutoff. This work establishes the integration of normal-metal components into the framework of circuit quantum electrodynamics15-17 which provides a basis for the superconducting quantum computer18-21. Especially, our results facilitate remote cooling of nanoelectronic devices using far-away in-situ-tunable heat sinks22, 23. Furthermore, quantum-limited heat conduction is important in contemporary thermodynamics24, 25. Here, the long distance may lead to ultimately efficient mesoscopic heat engines with promising practical applications26.
Oscillating streaming potential measurement system for macroscopic surfaces
NASA Astrophysics Data System (ADS)
Reischl, Martin; Köstler, Stefan; Kellner, Gerhard; Stana-Kleinschek, Karin; Ribitsch, Volker
2008-11-01
A method and instrumentation is described capable of streaming potential measurements of various macroscopic surfaces. It differs from other approaches due to the creation of an oscillatory flow of electrolyte solutions through or alongside the sample. This technique offers a wide range of applied flow frequency and amplitude resulting in a fast and highly accurate measurement. This enables the streaming potential detection at rather high ionic strength and in a short time regime, which allows the monitoring of adsorption processes. Streaming potential and applied pressure are measured simultaneously, together with the specific conductivity of the bulk solution, pH value, and temperature. Combining these data, the zeta potential (ζ ) for many different material types (fibers, films, foils, granules, and particles) can be calculated. The apparatus comprises reliable and robust measurements, simple handling, a high degree of automation, and advanced software control. With this setup, automated pH and concentration dependent ζ-potential measurements are possible for a variety of analytes and adsorbing species (e.g., ionic strength, surfactants, polyelectrolytes, and proteins); time-resolved measurements are facilitated down to the seconds time scale. The device allows the necessary sample preparation and equilibration outside the instrument using exchangeable sample holders. This offers the opportunity of high sample throughput.
Macroscopic effects of the spectral structure in turbulent flows
NASA Astrophysics Data System (ADS)
Tran, Tuan; Chakraborty, Pinaki; Guttenberg, Nicholas; Prescott, Alisia; Kellay, Hamid; Goldburg, Walter; Goldenfeld, Nigel; Gioia, Gustavo
2010-06-01
There is a missing link between the macroscopic properties of turbulent flows, such as the frictional drag of a wall-bounded flow, and the turbulent spectrum. The turbulent spectrum is a power law of exponent α (the `spectral exponent') that gives the characteristic velocity of a turbulent fluctuation (or `eddy') of size s as a function of s (ref. 1). Here we seek the missing link by comparing the frictional drag in soap-film flows, where α=3 (refs 9, 10), and in pipe flows, where α=5/3 (refs 11, 12). For moderate values of the Reynolds number Re, we find experimentally that in soap-film flows the frictional drag scales as Re-1/2, whereas in pipe flows the frictional drag scales as Re-1/4. Each of these scalings may be predicted from the attendant value of α by using a new theory, in which the frictional drag is explicitly linked to the turbulent spectrum.
Macroscopic effects of the spectral structure in turbulent flows
NASA Astrophysics Data System (ADS)
Tran, T.; Chakraborty, P.; Guttenberg, N.; Prescott, A.; Kellay, H.; Goldburg, W.; Goldenfeld, N.; Gioia, G.
2010-11-01
There is a missing link between macroscopic properties of turbulent flows, such as the frictional drag of a wall-bounded flow, and the turbulent spectrum. To seek the missing link we carry out unprecedented experimental measurements of the frictional drag in turbulent soap-film flows over smooth walls. These flows are effectively two-dimensional, and we are able to create soap-film flows with the two types of turbulent spectrum that are theoretically possible in two dimensions: the "enstrophy cascade," for which the spectral exponent α= 3, and the "inverse energy cascade," for which the spectral exponent α= 5/3. We find that the functional relation between the frictional drag f and the Reynolds number Re depends on the spectral exponent: where α= 3, f ˜Re-1/2; where α= 5/3, f ˜Re-1/4. Each of these scalings may be predicted from the attendant value of α by using a recently proposed spectral theory of the frictional drag. In this theory the frictional drag of turbulent flows on smooth walls is predicted to be f ˜Re^(1-α)/(1+α).
Single-file diffusion of macroscopic charged particles.
Coste, C; Delfau, J-B; Even, C; Saint Jean, M
2010-05-01
In this paper, we study a macroscopic system of electrically interacting metallic beads organized as a sequence along an annulus. A random mechanical shaking mimics the thermal excitation. We exhibit non-Fickian diffusion (single-file diffusion) at large time. We measure the mobility of the particles and compare it to theoretical expectations. We show that our system cannot be accurately described by theories assuming only hard-sphere interactions. Its behavior is qualitatively described by a theory extended to more realistic potentials [M. Kollmann, Phys. Rev. Lett. 90, 180602 (2003)]. A correct quantitative agreement is shown and we interpret the discrepancies by the violation of the assumption of overdamped dynamics, which is a key point in the theory. We recast previous results on colloids with known interaction potentials and compare them quantitatively to the theory. Focusing on the transition between ordinary and single-file diffusions, we exhibit a dimensionless crossover time that is of order 1 both for colloids and our system, although the time and length scales differ by several orders of magnitude.
Experiments testing macroscopic quantum superpositions must be slow
NASA Astrophysics Data System (ADS)
Mari, Andrea; de Palma, Giacomo; Giovannetti, Vittorio
2016-03-01
We consider a thought experiment where the preparation of a macroscopically massive or charged particle in a quantum superposition and the associated dynamics of a distant test particle apparently allow for superluminal communication. We give a solution to the paradox which is based on the following fundamental principle: any local experiment, discriminating a coherent superposition from an incoherent statistical mixture, necessarily requires a minimum time proportional to the mass (or charge) of the system. For a charged particle, we consider two examples of such experiments, and show that they are both consistent with the previous limitation. In the first, the measurement requires to accelerate the charge, that can entangle with the emitted photons. In the second, the limitation can be ascribed to the quantum vacuum fluctuations of the electromagnetic field. On the other hand, when applied to massive particles our result provides an indirect evidence for the existence of gravitational vacuum fluctuations and for the possibility of entangling a particle with quantum gravitational radiation.
Properties of nuclear matter from macroscopic-microscopic mass formulas
NASA Astrophysics Data System (ADS)
Wang, Ning; Liu, Min; Ou, Li; Zhang, Yingxun
2015-12-01
Based on the standard Skyrme energy density functionals together with the extended Thomas-Fermi approach, the properties of symmetric and asymmetric nuclear matter represented in two macroscopic-microscopic mass formulas: Lublin-Strasbourg nuclear drop energy (LSD) formula and Weizsäcker-Skyrme (WS*) formula, are extracted through matching the energy per particle of finite nuclei. For LSD and WS*, the obtained incompressibility coefficients of symmetric nuclear matter are K∞ = 230 ± 11 MeV and 235 ± 11 MeV, respectively. The slope parameter of symmetry energy at saturation density is L = 41.6 ± 7.6 MeV for LSD and 51.5 ± 9.6 MeV for WS*, respectively, which is compatible with the liquid-drop analysis of Lattimer and Lim [4]. The density dependence of the mean-field isoscalar and isovector effective mass, and the neutron-proton effective masses splitting for neutron matter are simultaneously investigated. The results are generally consistent with those from the Skyrme Hartree-Fock-Bogoliubov calculations and nucleon optical potentials, and the standard deviations are large and increase rapidly with density. A better constraint for the effective mass is helpful to reduce uncertainties of the depth of the mean-field potential.
Lasing optical cavities based on macroscopic scattering elements
NASA Astrophysics Data System (ADS)
Consoli, Antonio; López, Cefe
2017-01-01
Two major elements are required in a laser device: light confinement and light amplification. Light confinement is obtained in optical cavities by employing a pair of mirrors or by periodic spatial modulation of the refractive index as in photonic crystals and Bragg gratings. In random lasers, randomly placed nanoparticles embedded in the active material provide distributed optical feedback for lasing action. Recently, we demonstrated a novel architecture in which scattering nanoparticles and active element are spatially separated and random lasing is observed. Here we show that this approach can be extended to scattering media with macroscopic size, namely, a pair of sand grains, which act as feedback elements and output couplers, resulting in lasing emission. We demonstrate that the number of lasing modes depends on the surface roughness of the sand grains in use which affect the coherent feedback and thus the emission spectrum. Our findings offer a new perspective of material science and photonic structures, facilitating a novel and simple approach for the realization of new photonics devices based on natural scattering materials.
LETTERS AND COMMENTS: Adiabatic process reversibility: microscopic and macroscopic views
NASA Astrophysics Data System (ADS)
Anacleto, Joaquim; Pereira, Mário G.
2009-05-01
The reversibility of adiabatic processes was recently addressed by two publications. In the first (Miranda 2008 Eur. J. Phys. 29 937-43), an equation was derived relating the initial and final volumes and temperatures for adiabatic expansions of an ideal gas, using a microscopic approach. In that relation the parameter r accounts for the process reversibility, ranging between 0 and 1, which corresponds to the free and reversible expansion, respectively. In the second (Anacleto and Pereira 2009 Eur. J. Phys. 30 177-83), the authors have shown that thermodynamics can effectively and efficiently be used to obtain the general law for adiabatic processes carried out by an ideal gas, including compressions, for which r \\ge 1. The present work integrates and extends the aforementioned studies, providing thus further insights into the analysis of the adiabatic process. It is shown that Miranda's work is wholly valid for compressions. In addition, it is demonstrated that the adiabatic reversibility coefficient given in terms of the piston velocity and the root mean square velocity of the gas particles is equivalent to the macroscopic description, given just by the quotient between surroundings and system pressure values.
Macroscopic rotation of photon polarization induced by a single spin.
Arnold, Christophe; Demory, Justin; Loo, Vivien; Lemaître, Aristide; Sagnes, Isabelle; Glazov, Mikhaïl; Krebs, Olivier; Voisin, Paul; Senellart, Pascale; Lanco, Loïc
2015-02-17
Entangling a single spin to the polarization of a single incoming photon, generated by an external source, would open new paradigms in quantum optics such as delayed-photon entanglement, deterministic logic gates or fault-tolerant quantum computing. These perspectives rely on the possibility that a single spin induces a macroscopic rotation of a photon polarization. Such polarization rotations induced by single spins were recently observed, yet limited to a few 10(-3) degrees due to poor spin-photon coupling. Here we report the enhancement by three orders of magnitude of the spin-photon interaction, using a cavity quantum electrodynamics device. A single hole spin in a semiconductor quantum dot is deterministically coupled to a micropillar cavity. The cavity-enhanced coupling between the incoming photons and the solid-state spin results in a polarization rotation by ± 6° when the spin is optically initialized in the up or down state. These results open the way towards a spin-based quantum network.
Lasing optical cavities based on macroscopic scattering elements.
Consoli, Antonio; López, Cefe
2017-01-10
Two major elements are required in a laser device: light confinement and light amplification. Light confinement is obtained in optical cavities by employing a pair of mirrors or by periodic spatial modulation of the refractive index as in photonic crystals and Bragg gratings. In random lasers, randomly placed nanoparticles embedded in the active material provide distributed optical feedback for lasing action. Recently, we demonstrated a novel architecture in which scattering nanoparticles and active element are spatially separated and random lasing is observed. Here we show that this approach can be extended to scattering media with macroscopic size, namely, a pair of sand grains, which act as feedback elements and output couplers, resulting in lasing emission. We demonstrate that the number of lasing modes depends on the surface roughness of the sand grains in use which affect the coherent feedback and thus the emission spectrum. Our findings offer a new perspective of material science and photonic structures, facilitating a novel and simple approach for the realization of new photonics devices based on natural scattering materials.
Lasing optical cavities based on macroscopic scattering elements
Consoli, Antonio; López, Cefe
2017-01-01
Two major elements are required in a laser device: light confinement and light amplification. Light confinement is obtained in optical cavities by employing a pair of mirrors or by periodic spatial modulation of the refractive index as in photonic crystals and Bragg gratings. In random lasers, randomly placed nanoparticles embedded in the active material provide distributed optical feedback for lasing action. Recently, we demonstrated a novel architecture in which scattering nanoparticles and active element are spatially separated and random lasing is observed. Here we show that this approach can be extended to scattering media with macroscopic size, namely, a pair of sand grains, which act as feedback elements and output couplers, resulting in lasing emission. We demonstrate that the number of lasing modes depends on the surface roughness of the sand grains in use which affect the coherent feedback and thus the emission spectrum. Our findings offer a new perspective of material science and photonic structures, facilitating a novel and simple approach for the realization of new photonics devices based on natural scattering materials. PMID:28071675
Macroscopic Electrochemical Properties Clarified by Microscopic Measurements; Present and Future
NASA Astrophysics Data System (ADS)
Sugiyama, Jun
Although microscopic measurements, such as, Li-NMR and µ+ SR, provide fundamental information on Li-diffusion in solids, it is highly preferable to combine such information with the macroscopic properties in order to obtain a new insight to improve electrochemical properties of the whole battery system and/or to develop new electrode and electrolyte materials. In fact, the comparison between a diffusion coefficient of Li (DLi) with ionic conductivity provided the number density of mobile Li ions, i.e., carrier density in a garnet-type electrolyte material, Li5+xLa3ZrxNb1-xO12. Furthermore, when DLi obtained by µ+ SR is compared with DLi estimated by electrochemical measurements, a reactive surface of the cathode used for the electrochemical measurements was firstly derived as a function of the Li content (x) in the cathode material, Lix(Co1/3Ni1/3Mn1/3)O2. Finally, I will make an outlook towards future developments by means of a ultra-slow muon microscope.
The Unique Macroscopic Appearance of Gouty Arthritis of the Knee.
Mittl, Gregory S; Zuckerman, Joseph D
2015-07-01
Patients with significant gouty arthritis can develop disabling joint pain secondary to monosodium urate (MSU) articular deposition. We report a case of white, chalky MSU crystal deposition covering the articular surfaces of the knee as discovered by total knee arthroplasty. A 65-year-old male with a history of gout presented with bilateral knee pain. His radiographic imaging was negative for gouty tophi, and he elected to undergo left total knee arthroplasty. Intraoperatively a distinct chalky, white paste consistent with MSU deposition was observed covering the articular surfaces of the knee consistent with the diagnosis of gouty arthritis. Gout is the most common inflammatory arthritis affecting more than 3 million people in the USA. The inflammation results from the phagocytosis of monosodium urate crystals (MSU) and the release of inflammatory cytokines within the joint. Gout progresses from acute to chronic over many years and frequently causes chronic arthropathy. When significant knee pain and disability is associated with gouty arthropathy, total knee arthroplasty is certainly an option. The pathological appearance of gouty joints is characteristic. Macroscopic examination of joints affected by gout reveals a nodular, white, chalky appearance. Polarized microscopy of gout demonstrates negative birefringent needle-shaped MSU crystals. In this case report, we describe the characteristic chalky, white MSU deposit that covers the articular surfaces of a knee joint in a patient with a history of gout undergoing total knee arthroplasty. The investigators have obtained the patient's informed written consent for print and electronic publication of the case report.
Bridging the macroscopic and atomistic descriptions of the electrocaloric effect.
Ponomareva, I; Lisenkov, S
2012-04-20
First-principles-based simulations are used to simulate the electrocaloric effect (ECE) in Ba(0.5)Sr(0.5)TiO(3) alloys. In analogy with experimental studies we simulate the effect directly and indirectly (via the use of Maxwell thermodynamics). Both direct and indirect simulations utilize the same atomistic framework that allows us to compare them in a systematic way and with an atomistic precision for the very first time. Such precise comparison allows us to provide a bridge between the atomistic and macroscopic descriptions of the ECE and identify the factors that may critically compromise or even destroy their equivalence. Our computational data reveal the intrinsic features of ECE in ferroelectrics with multiple ferroelectric transitions and confirm the potential of these materials to exhibit giant electrocaloric response. The coexistence of negative and positive ECE in one material as well as an unusual field-driven transition between them is predicted, explained at an atomistic level, and proposed as a potential way to enhance the electrocaloric efficiency.
Atomistic study of macroscopic analogs to short-chain molecules.
Welch, Kyle J; Kilmer, Clayton S G; Corwin, Eric I
2015-02-01
We use a bath of chaotic surface waves in water to mechanically and macroscopically mimic the thermal behavior of a short articulated chain with only nearest-neighbor interactions. The chaotic waves provide isotropic and random agitation to which a temperature can be ascribed, allowing the chain to passively explore its degrees of freedom in analogy to thermal motion. We track the chain in real time and infer end-to-end potentials using Boltzmann statistics. We extrapolate our results, by using Monte Carlo simulations of self-avoiding polymers, to lengths not accessible in our system. In the long-chain limit we demonstrate universal scaling of the statistical parameters of all chains in agreement with well-known predictions for self-avoiding walks. However, we find that the behavior of chains below a characteristic length scale fundamentally differs. We find that short chains have much greater compressional stiffness than would be expected. However, chains rapidly soften as length increases to meet with expected scalings.
Zero time tunneling: macroscopic experiments with virtual particles
NASA Astrophysics Data System (ADS)
Nimtz, Günter; Aichmann, Horst
2015-05-01
Feynman introduced virtual particles in his diagrams as intermediate states of an interaction process. They represent necessary intermediate states between observable real states. Such virtual particles were introduced to describe the interaction process between an electron and a positron and for much more complicated interaction processes. Other candidates for virtual particles are evanescent modes in optics and in elastic fields. Evanescent modes have a purely imaginary wave number, they represent the mathematical analogy of the tunneling solutions of the Schrödinger equation. Evanescent modes exist in the forbidden frequency bands of a photonic lattice and in undersized wave guides, for instance. The most prominent example for the occurrence of evanescent modes is the frustrated total internal reflection (FTIR) at double prisms. Evanescent modes and tunneling lie outside the bounds of the special theory of relativity. They can cause faster than light (FTL) signal velocities. We present examples of the quantum mechanical behavior of evanescent photons and phonons at a macroscopic scale. The evanescent modes of photons are described by virtual particles as predicted by former QED calculations.
Macroscopic Neural Oscillation during Skilled Reaching Movements in Humans
Chung, Chun Kee
2016-01-01
The neural mechanism of skilled movements, such as reaching, has been considered to differ from that of rhythmic movement such as locomotion. It is generally thought that skilled movements are consciously controlled by the brain, while rhythmic movements are usually controlled autonomously by the spinal cord and brain stem. However, several studies in recent decades have suggested that neural networks in the spinal cord may also be involved in the generation of skilled movements. Moreover, a recent study revealed that neural activities in the motor cortex exhibit rhythmic oscillations corresponding to movement frequency during reaching movements as rhythmic movements. However, whether the oscillations are generated in the spinal cord or the cortical circuit in the motor cortex causes the oscillations is unclear. If the spinal cord is involved in the skilled movements, then similar rhythmic oscillations with time delays should be found in macroscopic neural activity. We measured whole-brain MEG signals during reaching. The MEG signals were analyzed using a dynamical analysis method. We found that rhythmic oscillations with time delays occur in all subjects during reaching movements. The results suggest that the corticospinal system is involved in the generation and control of the skilled movements as rhythmic movements. PMID:27524996
Experiments testing macroscopic quantum superpositions must be slow
Mari, Andrea; De Palma, Giacomo; Giovannetti, Vittorio
2016-01-01
We consider a thought experiment where the preparation of a macroscopically massive or charged particle in a quantum superposition and the associated dynamics of a distant test particle apparently allow for superluminal communication. We give a solution to the paradox which is based on the following fundamental principle: any local experiment, discriminating a coherent superposition from an incoherent statistical mixture, necessarily requires a minimum time proportional to the mass (or charge) of the system. For a charged particle, we consider two examples of such experiments, and show that they are both consistent with the previous limitation. In the first, the measurement requires to accelerate the charge, that can entangle with the emitted photons. In the second, the limitation can be ascribed to the quantum vacuum fluctuations of the electromagnetic field. On the other hand, when applied to massive particles our result provides an indirect evidence for the existence of gravitational vacuum fluctuations and for the possibility of entangling a particle with quantum gravitational radiation. PMID:26959656
Observation of quantum-limited heat conduction over macroscopic distances
NASA Astrophysics Data System (ADS)
Mottonen, Mikko; Partanen, Matti; Tan, Kuan Yen; Govenius, Joonas; Lake, Russell; Makela, Miika; Tanttu, Tuomo
The emerging quantum technological devices, such as the quantum computer, call for extreme performance in thermal engineering at the nanoscale. Importantly, quantum mechanics sets a fundamental upper limit for the flow of information and heat, which is quantified by the quantum of thermal conductance. We present experimental observations of quantum-limited heat conduction over macroscopic distances extending to a meter. We achieved this striking improvement of four orders of magnitude in the distance by utilizing microwave photons travelling in superconducting transmission lines. Thus it seems that quantum-limited heat conduction has no fundamental restriction in its distance. This work lays the foundation for the integration of normal-metal components into superconducting transmission lines, and hence provides an important tool for circuit quantum electrodynamics, the basis of the emerging superconducting quantum computer. In particular, our results may lead to remote cooling of nanoelectronic devices with the help of a far-away in-situ-tunable heat sink. European Research Council (ERC) is acknowledged for funding under the Grant No. 278117 (SINGLEOUT).
The macroscopic delamination of thin films from elastic substrates
Vella, Dominic; Bico, José; Boudaoud, Arezki; Roman, Benoit; Reis, Pedro M.
2009-01-01
The wrinkling and delamination of stiff thin films adhered to a polymer substrate have important applications in “flexible electronics.” The resulting periodic structures, when used for circuitry, have remarkable mechanical properties because stretching or twisting of the substrate is mostly accommodated through bending of the film, which minimizes fatigue or fracture. To date, applications in this context have used substrate patterning to create an anisotropic substrate-film adhesion energy, thereby producing a controlled array of delamination “blisters.” However, even in the absence of such patterning, blisters appear spontaneously, with a characteristic size. Here, we perform well-controlled experiments at macroscopic scales to study what sets the dimensions of these blisters in terms of the material properties and explain our results by using a combination of scaling and analytical methods. Besides pointing to a method for determining the interfacial toughness, our analysis suggests a number of design guidelines for the thin films used in flexible electronic applications. Crucially, we show that, to avoid the possibility that delamination may cause fatigue damage, the thin film thickness must be greater than a critical value, which we determine. PMID:19556551
Semiconductor spintronics in a participating phonon medium: Macroscopic equations
NASA Astrophysics Data System (ADS)
Rossani, A.
2013-09-01
In the last two decades considerable interest has arisen on the spin related phenomena in semiconductor devices. In semiconductor materials two essential mechanisms act on the spin dynamics: the spin-orbit coupling and the spin-flip interactions. Here the novelty is that we adopt the asymptotic approach developed in previous papers of mine [A. Rossani, Physica A 305, 323 (2002); A. Rossani, G. Spiga, and A. Domaingo, J. Phys. A 36, 11955 (2003); A. Rossani and G. Spiga, J. Math. Phys. 47, 013301 (2006); A. Rossani and A. M. Scarfone, Physica B 334, 292 (2003); A. Rossani, J. Phys. A 43, 165002 (2010)]. The aim of this paper is to derive macroscopic equations starting from a kinetic approach. Moreover an equation for the evolution of the spin density is added, which account for a general dispersion relation. The treatment of spin-flip processes, derived from first principles, is new and leads to an explicit expression of the relaxation time as a function of the temperature.
Macroscopic acousto-mechanical analogy of a microbubble.
Chaline, Jennifer; Jiménez, Noé; Mehrem, Ahmed; Bouakaz, Ayache; Dos Santos, Serge; Sánchez-Morcillo, Víctor J
2015-12-01
Microbubbles, either in the form of free gas bubbles surrounded by a fluid or encapsulated bubbles used currently as contrast agents for medical echography, exhibit complex dynamics under specific acoustic excitations. Nonetheless, considering their micron size and the complexity of their interaction phenomenon with ultrasound waves, expensive and complex experiments and/or simulations are required for their analysis. The behavior of a microbubble along its equator can be linked to a system of coupled oscillators. In this study, the oscillatory behavior of a microbubble has been investigated through an acousto-mechanical analogy based on a ring-shaped chain of coupled pendula. Observation of parametric vibration modes of the pendula ring excited at frequencies between 1 and 5 Hz is presented. Simulations have been carried out and show mode mixing phenomena. The relevance of the analogy between a microbubble and the macroscopic acousto-mechanical setup is discussed and suggested as an alternative way to investigate the complexity of microbubble dynamics.
Quantum-limited heat conduction over macroscopic distances
NASA Astrophysics Data System (ADS)
Partanen, Matti; Tan, Kuan Yen; Govenius, Joonas; Lake, Russell E.; Mäkelä, Miika K.; Tanttu, Tuomo; Möttönen, Mikko
2016-05-01
The emerging quantum technological apparatuses, such as the quantum computer, call for extreme performance in thermal engineering. Cold distant heat sinks are needed for the quantized electric degrees of freedom owing to the increasing packaging density and heat dissipation. Importantly, quantum mechanics sets a fundamental upper limit for the flow of information and heat, which is quantified by the quantum of thermal conductance. However, the short distance between the heat-exchanging bodies in the previous experiments hinders their applicability in quantum technology. Here, we present experimental observations of quantum-limited heat conduction over macroscopic distances extending to a metre. We achieved this improvement of four orders of magnitude in the distance by utilizing microwave photons travelling in superconducting transmission lines. Thus, it seems that quantum-limited heat conduction has no fundamental distance cutoff. This work establishes the integration of normal-metal components into the framework of circuit quantum electrodynamics, which provides a basis for the superconducting quantum computer. Especially, our results facilitate remote cooling of nanoelectronic devices using faraway in situ-tunable heat sinks. Furthermore, quantum-limited heat conduction is important in contemporary thermodynamics. Here, the long distance may lead to ultimately efficient mesoscopic heat engines with promising practical applications.
Quantum-limited heat conduction over macroscopic distances
Partanen, Matti; Tan, Kuan Yen; Govenius, Joonas; Lake, Russell E.; Mäkelä, Miika K.; Tanttu, Tuomo; Möttönen, Mikko
2016-01-01
The emerging quantum technological apparatuses1, 2, such as the quantum computer3–6, call for extreme performance in thermal engineering7. Cold distant heat sinks are needed for the quantized electric degrees of freedom due to the increasing packaging density and heat dissipation. Importantly, quantum mechanics sets a fundamental upper limit for the flow of information and heat, which is quantified by the quantum of thermal conductance8–10. However, the short distance between the heat-exchanging bodies in the previous experiments11–14 hinders their applicability in quantum technology. Here, we present experimental observations of quantum-limited heat conduction over macroscopic distances extending to a metre. We achieved this improvement of four orders of magnitude in the distance by utilizing microwave photons travelling in superconducting transmission lines. Thus, it seems that quantum-limited heat conduction has no fundamental distance cutoff. This work establishes the integration of normal-metal components into the framework of circuit quantum electrodynamics15–17 which provides a basis for the superconducting quantum computer18–21. Especially, our results facilitate remote cooling of nanoelectronic devices using far-away in-situ-tunable heat sinks22, 23. Furthermore, quantum-limited heat conduction is important in contemporary thermodynamics24, 25. Here, the long distance may lead to ultimately efficient mesoscopic heat engines with promising practical applications26. PMID:27239219
Macroscopic strain controlled ion current in an elastomeric microchannel
Kuo, Chin-Chang; Nguyen, Du; Buchsbaum, Steven; Innes, Laura; Dennin, Michael; Li, Yongxue; Esser-Kahn, Aaron P.; Valdevit, Lorenzo; Sun, Lizhi; Siwy, Zuzanna
2015-05-07
We report on the fabrication of an ultra-high aspect ratio ionically conductive single microchannel with tunable diameter from ≈ 20 μm to fully closed. The 4 mm-long channel is fabricated in a Polydimethylsiloxane (PDMS) mold and its cross-sectional area is controlled by applying macroscopic compressive strain to the mold in a direction perpendicular to the channel length. We investigated the ionic conduction properties of the channel. For a wide range of compressive strain up to ≈ 0.27, the strain dependence of the resistance is monotonic and fully reversible. For strain > 0.27, ionic conduction suddenly shuts off and the system becomes hysteretic (whereby a finite strain reduction is required to reopen the channel). Upon unloading, the original behavior is retrieved. This reversible behavior is observed over 200 compression cycles. The cross-sectional area of the channel can be inferred from the ion current measurement, as confirmed by a Nano-Computed Tomography investigation. We show that the cross-sectional area decreases monotonically with the applied compressive strain in the reversible range, in qualitative agreement with linear elasticity theory. We find that the shut-off strain is affected by the spatial extent of the applied strain, which provides additional tunability. Our tunable channel is well-suited for multiple applications in micro/nano-fluidic devices.
Experiments testing macroscopic quantum superpositions must be slow.
Mari, Andrea; De Palma, Giacomo; Giovannetti, Vittorio
2016-03-09
We consider a thought experiment where the preparation of a macroscopically massive or charged particle in a quantum superposition and the associated dynamics of a distant test particle apparently allow for superluminal communication. We give a solution to the paradox which is based on the following fundamental principle: any local experiment, discriminating a coherent superposition from an incoherent statistical mixture, necessarily requires a minimum time proportional to the mass (or charge) of the system. For a charged particle, we consider two examples of such experiments, and show that they are both consistent with the previous limitation. In the first, the measurement requires to accelerate the charge, that can entangle with the emitted photons. In the second, the limitation can be ascribed to the quantum vacuum fluctuations of the electromagnetic field. On the other hand, when applied to massive particles our result provides an indirect evidence for the existence of gravitational vacuum fluctuations and for the possibility of entangling a particle with quantum gravitational radiation.
Graphene in macroscopic order: liquid crystals and wet-spun fibers.
Xu, Zhen; Gao, Chao
2014-04-15
In nanotechnology, the creation of new nanoparticles consistently feeds back into efforts to design and fabricate new macroscopic materials with specific properties. As a two-dimensional (2D) building block of new materials, graphene has received widespread attention due to its exceptional mechanical, electrical, and thermal properties. But harnessing these attributes into new materials requires developing methods to assemble single-atom-thick carbon flakes into macroscopically ordered structures. Because the melt processing of carbon materials is impossible, fluid assembly is the only viable approach for meeting this challenge. But in the meantime, researchers need to solve two fundamental problems: creating orientational ordering in fluids and the subsequent phase-transformation from ordered fluids into ordered solid materials. To address these problems, this Account highlights our graphene chemistry methods that take advantage of liquid crystals to produce graphene fibers. We have successfully synthesized graphene oxide (GO) from graphite in a scalable manner. Using the size of graphite particles and post fractionation, we successfully tuned the lateral size of GO from submicron sizes to dozens of microns. Based on the rich chemistry of GO, we developed reliable methods for chemical or physical functionalization of graphene and produced a series of functionalized, highly soluble graphene derivatives that behave as single layers even at high concentrations. In the dispersive system of GO and functionalized graphenes, rich liquid crystals (LCs) formed spontaneously. Some of these liquid crystals had a conventional nematic phase with orientational order; others had a lamellar phase. Importantly, we observed a new chiral mesophase featuring a helical-lamellar structural model with frustrated disinclinations. The graphene-based LCs show ordered assembly behaviors in the fluid state of 2D colloids and lay a foundation for the design of ordered materials with optimal
PolyMEMS Actuator: A Polymer-Based Microelectromechanical (MEMS) Actuator with Macroscopic Action
2002-09-01
Polymer Microactuator Array with Macroscopic Force and Displacement.” Cleopatra Cabuz, Robert Horning, William Herb. Issued 6 Feb. 2001. U.S. Patent...6,255,758. “Polymer Microactuator Array with Macroscopic Force and Displacement.” Cleopatra Cabuz, Robert Horning, William Herb. Issued 3 July
ERIC Educational Resources Information Center
Casanova, Manuel F.; El-Baz, Ayman; Mott, Meghan; Mannheim, Glenn; Hassan, Hossam; Fahmi, Rachid; Giedd, Jay; Rumsey, Judith M.; Switala, Andrew E.; Farag, Aly
2009-01-01
Minicolumnar changes that generalize throughout a significant portion of the cortex have macroscopic structural correlates that may be visualized with modern structural neuroimaging techniques. In magnetic resonance images (MRIs) of fourteen autistic patients and 28 controls, the present study found macroscopic morphological correlates to recent…
ERIC Educational Resources Information Center
Leinonen, Risto; Asikainen, Mervi A.; Hirvonen, Pekka E.
2015-01-01
This study concentrates on evaluating the consistency of upper-division students' use of the second law of thermodynamics at macroscopic and microscopic levels. Data were collected by means of a paper and pencil test (N = 48) focusing on the macroscopic and microscopic features of the second law concerned with heat transfer processes. The data…
Paéz-García, Catherine Teresa; Valdés-Parada, Francisco J; Lasseux, Didier
2017-02-01
Modeling flow in porous media is usually focused on the governing equations for mass and momentum transport, which yield the velocity and pressure at the pore or Darcy scales. However, in many applications, it is important to determine the work (or power) needed to induce flow in porous media, and this can be achieved when the mechanical energy equation is taken into account. At the macroscopic scale, this equation may be postulated to be the result of the inner product of Darcy's law and the seepage velocity. However, near the porous medium boundaries, this postulate seems questionable due to the spatial variations of the effective properties (velocity, permeability, porosity, etc.). In this work we derive the macroscopic mechanical energy equation using the method of volume averaging for the simple case of incompressible single-phase flow in porous media. Our analysis shows that the result of averaging the pore-scale version of the mechanical energy equation at the Darcy scale is not, in general, the expected product of Darcy's law and the seepage velocity. As a matter of fact, this result is only applicable in the bulk region of the porous medium and, in the derivation of this result, the properties of the permeability tensor are determinant. Furthermore, near the porous medium boundaries, a more novel version of the mechanical energy equation is obtained, which incorporates additional terms that take into account the rapid variations of structural properties taking place in this particular portion of the system. This analysis can be applied to multiphase and compressible flows in porous media and in many other multiscale systems.
NASA Astrophysics Data System (ADS)
Paéz-García, Catherine Teresa; Valdés-Parada, Francisco J.; Lasseux, Didier
2017-02-01
Modeling flow in porous media is usually focused on the governing equations for mass and momentum transport, which yield the velocity and pressure at the pore or Darcy scales. However, in many applications, it is important to determine the work (or power) needed to induce flow in porous media, and this can be achieved when the mechanical energy equation is taken into account. At the macroscopic scale, this equation may be postulated to be the result of the inner product of Darcy's law and the seepage velocity. However, near the porous medium boundaries, this postulate seems questionable due to the spatial variations of the effective properties (velocity, permeability, porosity, etc.). In this work we derive the macroscopic mechanical energy equation using the method of volume averaging for the simple case of incompressible single-phase flow in porous media. Our analysis shows that the result of averaging the pore-scale version of the mechanical energy equation at the Darcy scale is not, in general, the expected product of Darcy's law and the seepage velocity. As a matter of fact, this result is only applicable in the bulk region of the porous medium and, in the derivation of this result, the properties of the permeability tensor are determinant. Furthermore, near the porous medium boundaries, a more novel version of the mechanical energy equation is obtained, which incorporates additional terms that take into account the rapid variations of structural properties taking place in this particular portion of the system. This analysis can be applied to multiphase and compressible flows in porous media and in many other multiscale systems.
NASA Technical Reports Server (NTRS)
Crawford, D. A.; Schultz, P. H.
1993-01-01
The production of transient magnetic fields by hypervelocity meteoroid impact has been proposed to possibly explain the presence of paleomagnetic fields in certain lunar samples as well as across broader areas of the lunar surface. In an effort to understand the lunar magnetic record, continued experiments at the NASA Ames Vertical Gun Range allow characterizing magnetic fields produced by the 5 km/s impacts of 0.32-0.64 cm projectiles over a broad range of impact angles and projectile/target compositions. From such studies, another phenomenon has emerged, macroscopic electric charge separation, that may have importance for the magnetic state of solid-body surfaces. This phenomenon was observed during explosive cratering experiments, but the magnetic consequences of macroscopic electric charge separation (as opposed to plasma production) during explosion and impact cratering have not, to our knowledge, been explored before now. It is straightforward to show that magnetic field production due to this process may scale as a weakly increasing function of impactor kinetic energy, although more work is needed to precisely assess the scaling dependence. The original intent of our experiments was to assess the character of purely electrostatic signals for comparison with inferred electrostatic noise signals acquired by shielded magnetic sensors buried within particulate dolomite targets. The results demonstrated that electrostatic noise does affect the magnetic sensors but only at relatively short distances (less than 4 cm) from the impact point (our magnetic studies are generally performed at distances greater than approximately 5.5 cm). However, to assess models for magnetic field generation during impact, measurements are needed of the magnetic field as close to the impact point as possible; hence, work with an improved magnetic sensor design is in progress. In this paper, we focus on electric charge separation during hypervelocity impacts as a potential transient
Detection of cancer metastasis using a novel macroscopic hyperspectral method
NASA Astrophysics Data System (ADS)
Akbari, Hamed; Halig, Luma V.; Zhang, Hongzheng; Wang, Dongsheng; Chen, Zhuo G.; Fei, Baowei
2012-03-01
The proposed macroscopic optical histopathology includes a broad-band light source which is selected to illuminate the tissue glass slide of suspicious pathology, and a hyperspectral camera that captures all wavelength bands from 450 to 950 nm. The system has been trained to classify each histologic slide based on predetermined pathology with light having a wavelength within a predetermined range of wavelengths. This technology is able to capture both the spatial and spectral data of tissue. Highly metastatic human head and neck cancer cells were transplanted to nude mice. After 2- 3 weeks, the mice were euthanized and the lymph nodes and lung tissues were sent to pathology. The metastatic cancer is studied in lymph nodes and lungs. The pathological slides were imaged using the hyperspectral camera. The results of the proposed method were compared to the pathologic report. Using hyperspectral images, a library of spectral signatures for different tissues was created. The high-dimensional data were classified using a support vector machine (SVM). The spectra are extracted in cancerous and non-cancerous tissues in lymph nodes and lung tissues. The spectral dimension is used as the input of SVM. Twelve glasses are employed for training and evaluation. The leave-one-out cross-validation method is used in the study. After training, the proposed SVM method can detect the metastatic cancer in lung histologic slides with the specificity of 97.7% and the sensitivity of 92.6%, and in lymph node slides with the specificity of 98.3% and the sensitivity of 96.2%. This method may be able to help pathologists to evaluate many histologic slides in a short time.
Proton irradiation effects on beryllium – A macroscopic assessment
Simos, Nikolaos; Elbakhshwan, Mohamed; Zhong, Zhong; Camino, Fernando
2016-07-01
Beryllium, due to its excellent neutron multiplication and moderation properties, in conjunction with its good thermal properties, is under consideration for use as plasma facing material in fusion reactors and as a very effective neutron reflector in fission reactors. While it is characterized by unique combination of structural, chemical, atomic number, and neutron absorption cross section it suffers, however, from irradiation generated transmutation gases such as helium and tritium which exhibit low solubility leading to supersaturation of the Be matrix and tend to precipitate into bubbles that coalesce and induce swelling and embrittlement thus degrading the metal and limiting its lifetime. Utilization of beryllium as a pion production low-Z target in high power proton accelerators has been sought both for its low Z and good thermal properties in an effort to mitigate thermos-mechanical shock that is expected to be induced under the multi-MW power demand. To assess irradiation-induced changes in the thermal and mechanical properties of Beryllium, a study focusing on proton irradiation damage effects has been undertaken using 200 MeV protons from the Brookhaven National Laboratory Linac and followed by a multi-faceted post-irradiation analysis that included the thermal and volumetric stability of irradiated beryllium, the stress-strain behavior and its ductility loss as a function of proton fluence and the effects of proton irradiation on the microstructure using synchrotron X-ray diffraction. The mimicking of high temperature irradiation of Beryllium via high temperature annealing schemes has been conducted as part of the post-irradiation study. This study focuses on the thermal stability and mechanical property changes of the proton irradiated beryllium and presents results of the macroscopic property changes of Beryllium deduced from thermal and mechanical tests.
Proton irradiation effects on beryllium - A macroscopic assessment
NASA Astrophysics Data System (ADS)
Simos, Nikolaos; Elbakhshwan, Mohamed; Zhong, Zhong; Camino, Fernando
2016-10-01
Beryllium, due to its excellent neutron multiplication and moderation properties, in conjunction with its good thermal properties, is under consideration for use as plasma facing material in fusion reactors and as a very effective neutron reflector in fission reactors. While it is characterized by unique combination of structural, chemical, atomic number, and neutron absorption cross section it suffers, however, from irradiation generated transmutation gases such as helium and tritium which exhibit low solubility leading to supersaturation of the Be matrix and tend to precipitate into bubbles that coalesce and induce swelling and embrittlement thus degrading the metal and limiting its lifetime. Utilization of beryllium as a pion production low-Z target in high power proton accelerators has been sought both for its low Z and good thermal properties in an effort to mitigate thermos-mechanical shock that is expected to be induced under the multi-MW power demand. To assess irradiation-induced changes in the thermal and mechanical properties of Beryllium, a study focusing on proton irradiation damage effects has been undertaken using 200 MeV protons from the Brookhaven National Laboratory Linac and followed by a multi-faceted post-irradiation analysis that included the thermal and volumetric stability of irradiated beryllium, the stress-strain behavior and its ductility loss as a function of proton fluence and the effects of proton irradiation on the microstructure using synchrotron X-ray diffraction. The mimicking of high temperature irradiation of Beryllium via high temperature annealing schemes has been conducted as part of the post-irradiation study. This paper focuses on the thermal stability and mechanical property changes of the proton irradiated beryllium and presents results of the macroscopic property changes of Beryllium deduced from thermal and mechanical tests.
Proton irradiation effects on beryllium – A macroscopic assessment
Simos, Nikolaos; Elbakhshwan, Mohamed; Zhong, Zhong; ...
2016-07-01
Beryllium, due to its excellent neutron multiplication and moderation properties, in conjunction with its good thermal properties, is under consideration for use as plasma facing material in fusion reactors and as a very effective neutron reflector in fission reactors. While it is characterized by unique combination of structural, chemical, atomic number, and neutron absorption cross section it suffers, however, from irradiation generated transmutation gases such as helium and tritium which exhibit low solubility leading to supersaturation of the Be matrix and tend to precipitate into bubbles that coalesce and induce swelling and embrittlement thus degrading the metal and limiting itsmore » lifetime. Utilization of beryllium as a pion production low-Z target in high power proton accelerators has been sought both for its low Z and good thermal properties in an effort to mitigate thermos-mechanical shock that is expected to be induced under the multi-MW power demand. To assess irradiation-induced changes in the thermal and mechanical properties of Beryllium, a study focusing on proton irradiation damage effects has been undertaken using 200 MeV protons from the Brookhaven National Laboratory Linac and followed by a multi-faceted post-irradiation analysis that included the thermal and volumetric stability of irradiated beryllium, the stress-strain behavior and its ductility loss as a function of proton fluence and the effects of proton irradiation on the microstructure using synchrotron X-ray diffraction. The mimicking of high temperature irradiation of Beryllium via high temperature annealing schemes has been conducted as part of the post-irradiation study. This study focuses on the thermal stability and mechanical property changes of the proton irradiated beryllium and presents results of the macroscopic property changes of Beryllium deduced from thermal and mechanical tests.« less
Nuclear magnetic resonance studies of macroscopic morphology and dynamics
Barrall, Geoffrey Alden
1995-09-01
Nuclear magnetic resonance techniques are traditionally used to study molecular level structure and dynamics with a noted exception in medically applied NMR imaging (MRI). In this work, new experimental methods and theory are presented relevant to the study of macroscopic morphology and dynamics using NMR field gradient techniques and solid state two-dimensional exchange NMR. The goal in this work is not to take some particular system and study it in great detail, rather it is to show the utility of a number of new and novel techniques using ideal systems primarily as a proof of principle. By taking advantage of the analogy between NMR imaging and diffraction, one may simplify the experiments necessary for characterizing the statistical properties of the sample morphology. For a sample composed of many small features, e.g. a porous medium, the NMR diffraction techniques take advantage of both the narrow spatial range and spatial isotropy of the sample`s density autocorrelation function to obtain high resolution structural information in considerably less time than that required by conventional NMR imaging approaches. The time savings of the technique indicates that NMR diffraction is capable of finer spatial resolution than conventional NMR imaging techniques. Radio frequency NMR imaging with a coaxial resonator represents the first use of cylindrically symmetric field gradients in imaging. The apparatus as built has achieved resolution at the micron level for water samples, and has the potential to be very useful in the imaging of circularly symmetric systems. The study of displacement probability densities in flow through a random porous medium has revealed the presence of features related to the interconnectedness of the void volumes. The pulsed gradient techniques used have proven successful at measuring flow properties for time and length scales considerably shorter than those studied by more conventional techniques.
Automatic Detection of Malignant Melanoma using Macroscopic Images
Ramezani, Maryam; Karimian, Alireza; Moallem, Payman
2014-01-01
In order to distinguish between benign and malignant types of pigmented skin lesions, computerized procedures have been developed for images taken by different equipment that the most available one of them is conventional digital cameras. In this research, a new procedure to detect malignant melanoma from benign pigmented lesions using macroscopic images is presented. The images are taken by conventional digital cameras with spatial resolution higher than one megapixel and by considering no constraints and special conditions during imaging. In the proposed procedure, new methods to weaken the effect of nonuniform illumination, correction of the effect of thick hairs and large glows on the lesion and also, a new threshold-based segmentation algorithm are presented. 187 features representing asymmetry, border irregularity, color variation, diameter and texture are extracted from the lesion area and after reducing the number of features using principal component analysis (PCA), lesions are determined as malignant or benign using support vector machine classifier. According to the dermatologist diagnosis, the proposed processing methods have the ability to detect lesions area with high accuracy. The evaluation measures of classification have indicated that 13 features extracted by PCA method lead to better results than all of the extracted features. These results led to an accuracy of 82.2%, sensitivity of 77% and specificity of 86.93%. The proposed method may help dermatologists to detect the malignant lesions in the primary stages due to the minimum constraints during imaging, the ease of usage by the public and nonexperts, and high accuracy in detection of the lesion type. PMID:25426432
Moran, J M; Nigg, D W; Wheeler, F J; Bauer, W F
1992-01-01
Calculations of radiation flux and dose distributions for boron neutron capture therapy (BNCT) of brain tumors are typically performed using sophisticated three-dimensional analytical models based on either a homogeneous approximation or a simplified few-region approximation to the actual highly heterogeneous geometry of the irradiation volume. Such models should be validated by comparison with calculations using detailed models in which all significant macroscopic tissue heterogeneities and geometric structures are explicitly represented as faithfully as possible. This paper describes such a validation exercise for BNCT of canine brain tumors. Geometric measurements of the canine anatomical structures of interest for this work were performed by dissecting and examining two essentially identical Labrador retriever heads. Chemical analyses of various tissue samples taken during the dissections were conducted to obtain measurements of elemental compositions for the tissues of interest. The resulting geometry and tissue composition data were then used to construct a detailed heterogeneous calculational model of the Labrador head. Calculations of three-dimensional radiation flux distributions pertinent to BNCT were performed for this model using the TORT discrete-ordinates radiation transport code. The calculations were repeated for a corresponding volume-weighted homogeneous-tissue model. Comparison of the results showed that peak neutron and photon flux magnitudes were quite similar for the two models (within 5%), but that the spatial flux profiles were shifted in the heterogeneous model such that the fluxes in some locations away from the peak differed from the corresponding fluxes in the homogeneous model by as much as 10%-20%. Differences of this magnitude can be therapeutically significant, emphasizing the need for proper validation of simplified treatment planning models.
Avitable, Daniele; Wedgwood, Kyle C A
2017-02-01
We study coarse pattern formation in a cellular automaton modelling a spatially-extended stochastic neural network. The model, originally proposed by Gong and Robinson (Phys Rev E 85(5):055,101(R), 2012), is known to support stationary and travelling bumps of localised activity. We pose the model on a ring and study the existence and stability of these patterns in various limits using a combination of analytical and numerical techniques. In a purely deterministic version of the model, posed on a continuum, we construct bumps and travelling waves analytically using standard interface methods from neural field theory. In a stochastic version with Heaviside firing rate, we construct approximate analytical probability mass functions associated with bumps and travelling waves. In the full stochastic model posed on a discrete lattice, where a coarse analytic description is unavailable, we compute patterns and their linear stability using equation-free methods. The lifting procedure used in the coarse time-stepper is informed by the analysis in the deterministic and stochastic limits. In all settings, we identify the synaptic profile as a mesoscopic variable, and the width of the corresponding activity set as a macroscopic variable. Stationary and travelling bumps have similar meso- and macroscopic profiles, but different microscopic structure, hence we propose lifting operators which use microscopic motifs to disambiguate them. We provide numerical evidence that waves are supported by a combination of high synaptic gain and long refractory times, while meandering bumps are elicited by short refractory times.
Macroscopic and Microscopic Analysis of the Thumb Carpometacarpal Ligaments
Ladd, Amy L.; Lee, Julia; Hagert, Elisabet
2012-01-01
Background: Stability and mobility represent the paradoxical demands of the human thumb carpometacarpal joint, yet the structural origin of each functional demand is poorly defined. As many as sixteen and as few as four ligaments have been described as primary stabilizers, but controversy exists as to which ligaments are most important. We hypothesized that a comparative macroscopic and microscopic analysis of the ligaments of the thumb carpometacarpal joint would further define their role in joint stability. Methods: Thirty cadaveric hands (ten fresh-frozen and twenty embalmed) from nineteen cadavers (eight female and eleven male; average age at the time of death, seventy-six years) were dissected, and the supporting ligaments of the thumb carpometacarpal joint were identified. Ligament width, length, and thickness were recorded for morphometric analysis and were compared with use of the Student t test. The dorsal and volar ligaments were excised from the fresh-frozen specimens and were stained with use of a triple-staining immunofluorescent technique and underwent semiquantitative analysis of sensory innervation; half of these specimens were additionally analyzed for histomorphometric data. Mixed-effects linear regression was used to estimate differences between ligaments. Results: Seven principal ligaments of the thumb carpometacarpal joint were identified: three dorsal deltoid-shaped ligaments (dorsal radial, dorsal central, posterior oblique), two volar ligaments (anterior oblique and ulnar collateral), and two ulnar ligaments (dorsal trapeziometacarpal and intermetacarpal). The dorsal ligaments were significantly thicker (p < 0.001) than the volar ligaments, with a significantly greater cellularity and greater sensory innervation compared with the anterior oblique ligament (p < 0.001). The anterior oblique ligament was consistently a thin structure with a histologic appearance of capsular tissue with low cellularity. Conclusions: The dorsal deltoid ligament
Xue, Chuan
2015-01-01
Chemotaxis of single cells has been extensively studied and a great deal on intracellular signaling and cell movement is known. However, systematic methods to embed such information into continuum PDE models for cell population dynamics are still in their infancy. In this paper, we consider chemotaxis of run-and-tumble bacteria and derive continuum models that take into account of the detailed biochemistry of intracellular signaling. We analytically show that the macroscopic bacterial density can be approximated by the Patlak-Keller-Segel equation in response to signals that change slowly in space and time. We derive, for the first time, general formulas that represent the chemotactic sensitivity in terms of detailed descriptions of single-cell signaling dynamics in arbitrary space dimensions. These general formulas are useful in explaining relations of single cell behavior and population dynamics. As an example, we apply the theory to chemotaxis of bacterium Escherichia coli and show how the structure and kinetics of the intracellular signaling network determine the sensing properties of E. coli populations. Numerical comparison of the derived PDEs and the underlying cell-based models show quantitative agreements for signals that change slowly, and qualitative agreements for signals that change extremely fast. The general theory we develop here is readily applicable to chemotaxis of other run-and-tumble bacteria, or collective behavior of other individuals that move using a similar strategy.
NASA Astrophysics Data System (ADS)
Aryasova, Natalie; Reznikov, Yuri
2016-09-01
We study the effect of an isotropic-nematic (I -N ) phase transition on the liquid crystal alignment at untreated polymer surfaces. We demonstrate that the pattern at the untreated substrate in the planar cell where the other substrate is uniformly rubbed strongly depends on the temperature gradient across the cell during the I -N phase transition, being macroscopically isotropic if the untreated substrate is cooled faster, but becoming almost homogeneous along the rubbing direction in the opposite temperature gradient. We interpret the observed effect using complementary models of heat transfer and nematic elasticity. Based on the heat transfer model we show that the asymmetric temperature conditions in our experiments provide unidirectional propagation of the I -N interface during the phase transition and determine the initial director orientation pattern at the test's untreated surface. Using the Frank-Oseen model of nematic elasticity, we represent the three-dimensional director field in the nematic cell as a two-dimensional (2D) pattern at the untreated surface and perform 2D numeric simulations. The simulations explain the experimental results: Different initial director orientations at the untreated surface evolve into different stationary patterns.
NASA Astrophysics Data System (ADS)
Chang, Qiang; Herbst, Eric
2016-03-01
The recent discovery of methyl formate and dimethyl ether in the gas phase of cold cores with temperatures as cold as 10 K challenges our previous astrochemical models concerning the formation of complex organic molecules (COMs). The strong correlation between the abundances and distributions of methyl formate and dimethyl ether further shows that current astrochemical models may be missing important chemical processes in cold astronomical sources. We investigate a scenario in which COMs and the methoxy radical can be formed on dust grains via a so-called chain reaction mechanism, in a similar manner to CO2. A unified gas-grain microscopic-macroscopic Monte Carlo approach with both normal and interstitial sites for icy grain mantles is used to perform the chemical simulations. Reactive desorption with varying degrees of efficiency is included to enhance the nonthermal desorption of species formed on cold dust grains. In addition, varying degrees of efficiency for the surface formation of methoxy are also included. The observed abundances of a variety of organic molecules in cold cores can be reproduced in our models. The strong correlation between the abundances of methyl formate and dimethyl ether in cold cores can also be explained. Nondiffusive chemical reactions on dust grain surfaces may play a key role in the formation of some COMs.
Velazquez, J L Perez; Erra, R Guevara; Rosenblum, M
2015-02-12
The rhythmic activity observed in nervous systems, in particular in epilepsies and Parkinson's disease, has often been hypothesized to originate from a macroscopic self-sustained neural oscillator. However, this assumption has not been tested experimentally. Here we support this viewpoint with in vivo experiments in a rodent model of absence seizures, by demonstrating frequency locking to external periodic stimuli and finding the characteristic Arnold tongue. This result has important consequences for developing methods for the control of brain activity, such as seizure cancellation.
NASA Astrophysics Data System (ADS)
Velazquez, J. L. Perez; Erra, R. Guevara; Rosenblum, M.
2015-02-01
The rhythmic activity observed in nervous systems, in particular in epilepsies and Parkinson's disease, has often been hypothesized to originate from a macroscopic self-sustained neural oscillator. However, this assumption has not been tested experimentally. Here we support this viewpoint with in vivo experiments in a rodent model of absence seizures, by demonstrating frequency locking to external periodic stimuli and finding the characteristic Arnold tongue. This result has important consequences for developing methods for the control of brain activity, such as seizure cancellation.
Song, Bo; Chen, Kun; Schmittel, Michael; Schönherr, Holger
2016-11-01
All experimental findings related to surface nanobubbles, such as their pronounced stability and the striking differences of macroscopic and apparent nanoscopic contact angles, need to be addressed in any theory or model of surface nanobubbles. In this work we critically test a recent explanation of surface nanobubble stability and their consequences and contrast this with previously proposed models. In particular, we elucidated the effect of surface chemical composition of well-controlled solid-aqueous interfaces of identical roughness and defect density on the apparent nanoscopic contact angles. Expanding on a previous atomic force microscopy (AFM) study on the systematic variation of the macroscopic wettability using binary self-assembled monolayers (SAMs) on ultraflat template stripped gold (TSG), we assessed here the effect of different surface chemical composition for macroscopically identical static water contact angles. SAMs on TSG with a constant macroscopic water contact angle of 81 ± 2° were obtained by coadsorption of a methyl-terminated thiol and a second thiol with different terminal functional groups, including hydroxy, amino, and carboxylic acid groups. In addition, surface nanobubbles formed by entrainment of air on SAMs of a bromoisobutyrate-terminated thiol were analyzed by AFM. Despite the widely differing surface potentials and different functionality, such as hydrogen bond acceptor or donor, and different dipole moments and polarizability, the nanoscopic contact angles (measured through the condensed phase and corrected for AFM tip broadening effects) were found to be 145 ± 10° for all surfaces. Hence, different chemical functionalities at identical macroscopic static water contact angle do not noticeably influence the apparent nanoscopic contact angle of surface nanobubbles. This universal contact angle is in agreement with recent models that rely on contact line pinning and the equilibrium of gas outflux due to the Laplace pressure and
Macroscopic laws for immiscible two-phase flow in porous media: Results From numerical experiments
NASA Astrophysics Data System (ADS)
Rothman, Daniel H.
1990-06-01
Flow through porous media may be described at either of two length scales. At the scale of a single pore, fluids flow according to the Navier-Stokes equations and the appropriate boundary conditions. At a larger, volume-averaged scale, the flow is usually thought to obey a linear Darcy law relating flow rates to pressure gradients and body forces via phenomenological permeability coefficients. Aside from the value of the permeability coefficient, the slow flow of a single fluid in a porous medium is well-understood within this framework. The situation is considerably different, however, for the simultaneous flow of two or more fluids: not only are the phenomenological coefficients poorly understood, but the form of the macroscopic laws themselves is subject to question. I describe a numerical study of immiscible two-phase flow in an idealized two-dimensional porous medium constructed at the pore scale. Results show that the macroscopic flow is a nonlinear function of the applied forces for sufficiently low levels of forcing, but linear thereafter. The crossover, which is not predicted by conventional models, occurs when viscous forces begin to dominate capillary forces; i.e., at a sufficiently high capillary number. In the linear regime, the flow may be described by the linear phenomenological law ui = ΣjLijfj, where the flow rate ui of the ith fluid is related to the force fj applied to the jth fluid by the matrix of phenomenological coefficients Lij which depends on the relative concentrations of the two fluids. The diagonal terms are proportional to quantities commonly referred to as "relative permeabilities." The cross terms represent viscous coupling between the two fluids; they are conventionally assumed to be negligible and require special experimental procedures to observe in a laboratory. In contrast, in this numerical study the cross terms are straightforward to measure and are found to be of significant size. The cross terms are additionally observed to
Jin Cheng; Le, Anh-Thu; Lin, C. D.
2009-05-15
We investigate high-order harmonic generation (HHG) in a thin macroscopic medium by solving Maxwell's equation using microscopic single-atom induced dipole moment calculated from the recently developed quantitative rescattering (QRS) theory. We show that macroscopic HHG yields calculated from QRS compared well with those obtained from solving the single-atom time-dependent Schroedinger equation but with great saving of computer time. We also show that macroscopic HHG can be expressed as a product of a 'macroscopic wave packet' and the photorecombination cross section of the target gas. The latter enables us to extract target structure from the experimentally measured HHG spectra, thus paves the way to use few-cycle infrared lasers for time-resolved chemical imaging of transient molecules with few-femtosecond temporal resolution.
NASA Astrophysics Data System (ADS)
Kobelev, Nikolay P.; Lebyodkin, Mikhail A.; Lebedkina, Tatiana A.
2017-01-01
The present paper examines two aspects of the problem of critical conditions of jerky flow in alloys, or the Portevin-Le Chatelier (PLC) effect. Recent development of dynamic strain aging (DSA) models proved their capacity to qualitatively reproduce complex non-monotonic behavior of the critical strain, providing that the parameters of theory are allowed to depend on strain. Experimental measurements of such strain dependences have been realized for the first time and used to revise the predictions of the critical strain and stress relaxation kinetics upon abrupt strain-rate changes. On the other hand, it is usually omitted from consideration that the PLC stress serrations can last very short time in comparison with the characteristic time of stress transients. The development of stress drops was studied with the aid of the acoustic emission (AE) technique. It is shown that such macroscopic instabilities are caused by clustering of AE events which otherwise occur all the time, including the periods of smooth plastic flow. The role of synchronization of dislocation avalanches in the development of abrupt stress serrations and its relationship with the predictions of the local DSA models is discussed.
NASA Astrophysics Data System (ADS)
Kobelev, Nikolay P.; Lebyodkin, Mikhail A.; Lebedkina, Tatiana A.
2017-03-01
The present paper examines two aspects of the problem of critical conditions of jerky flow in alloys, or the Portevin-Le Chatelier (PLC) effect. Recent development of dynamic strain aging (DSA) models proved their capacity to qualitatively reproduce complex non-monotonic behavior of the critical strain, providing that the parameters of theory are allowed to depend on strain. Experimental measurements of such strain dependences have been realized for the first time and used to revise the predictions of the critical strain and stress relaxation kinetics upon abrupt strain-rate changes. On the other hand, it is usually omitted from consideration that the PLC stress serrations can last very short time in comparison with the characteristic time of stress transients. The development of stress drops was studied with the aid of the acoustic emission (AE) technique. It is shown that such macroscopic instabilities are caused by clustering of AE events which otherwise occur all the time, including the periods of smooth plastic flow. The role of synchronization of dislocation avalanches in the development of abrupt stress serrations and its relationship with the predictions of the local DSA models is discussed.
Aschwanden, Markus J.
2014-02-10
We suggest a generalized definition of self-organized criticality (SOC) systems: SOC is a critical state of a nonlinear energy dissipation system that is slowly and continuously driven toward a critical value of a system-wide instability threshold, producing scale-free, fractal-diffusive, and intermittent avalanches with power law-like size distributions. We develop here a macroscopic description of SOC systems that provides an equivalent description of the complex microscopic fine structure, in terms of fractal-diffusive transport (FD-SOC). Quantitative values for the size distributions of SOC parameters (length scales L, time scales T, waiting times Δt, fluxes F, and fluences or energies E) are derived from first principles, using the scale-free probability conjecture, N(L)dL∝L {sup –d}, for Euclidean space dimension d. We apply this model to astrophysical SOC systems, such as lunar craters, the asteroid belt, Saturn ring particles, magnetospheric substorms, radiation belt electrons, solar flares, stellar flares, pulsar glitches, soft gamma-ray repeaters, black-hole objects, blazars, and cosmic rays. The FD-SOC model predicts correctly the size distributions of 8 out of these 12 astrophysical phenomena, and indicates non-standard scaling laws and measurement biases for the others.
NASA Astrophysics Data System (ADS)
Aschwanden, Markus J.
2014-02-01
We suggest a generalized definition of self-organized criticality (SOC) systems: SOC is a critical state of a nonlinear energy dissipation system that is slowly and continuously driven toward a critical value of a system-wide instability threshold, producing scale-free, fractal-diffusive, and intermittent avalanches with power law-like size distributions. We develop here a macroscopic description of SOC systems that provides an equivalent description of the complex microscopic fine structure, in terms of fractal-diffusive transport (FD-SOC). Quantitative values for the size distributions of SOC parameters (length scales L, time scales T, waiting times Δt, fluxes F, and fluences or energies E) are derived from first principles, using the scale-free probability conjecture, N(L)dLvpropL -d , for Euclidean space dimension d. We apply this model to astrophysical SOC systems, such as lunar craters, the asteroid belt, Saturn ring particles, magnetospheric substorms, radiation belt electrons, solar flares, stellar flares, pulsar glitches, soft gamma-ray repeaters, black-hole objects, blazars, and cosmic rays. The FD-SOC model predicts correctly the size distributions of 8 out of these 12 astrophysical phenomena, and indicates non-standard scaling laws and measurement biases for the others.
Strongly Coupled Plasmonic Modes on Macroscopic Areas via Template-Assisted Colloidal Self-Assembly
2014-01-01
We present ensembles of surface-ordered nanoparticle arrangements, which are formed by template-assisted self-assembly of monodisperse, protein-coated gold nanoparticles in wrinkle templates. Centimeter-squared areas of highly regular, linear assemblies with tunable line width are fabricated and their extinction cross sections can be characterized by conventional UV/vis/NIR spectroscopy. Modeling based on electrodynamic simulations shows a clear signature of strong plasmonic coupling with an interparticle spacing of 1–2 nm. We find evidence for well-defined plasmonic modes of quasi-infinite chains, such as resonance splitting and multiple radiant modes. Beyond elementary simulations on the individual chain level, we introduce an advanced model, which considers the chain length distribution as well as disorder. The step toward macroscopic sample areas not only opens perspectives for a range of applications in sensing, plasmonic light harvesting, surface enhanced spectroscopy, and information technology but also eases the investigation of hybridization and metamaterial effects fundamentally. PMID:25347293
Critical Current in YBCO Coated Conductors in the Presence of a Macroscopic Defect (POSTPRINT)
2010-03-01
AFRL-RZ-WP-TP-2010-2084 CRITICAL CURRENT IN YBCO COATED CONDUCTORS IN THE PRESENCE OF A MACROSCOPIC DEFECT (POSTPRINT) Milan Polak and...CRITICAL CURRENT IN YBCO COATED CONDUCTORS IN THE PRESENCE OF A MACROSCOPIC DEFECT (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c...display, or disclose the work. 14. ABSTRACT We have studied the effects of localized defects in the YBCO coated conductors on the critical current. The
Fuchs, Thomas; Hain, Rainer; Kähler, Christian J
2014-03-01
This Letter presents a theoretical and experimental image formation study in the presence of astigmatic aberrations. A three-dimensional, macroscopic location scheme of micrometer-sized particles for the single camera astigmatism particle tracking velocimetry (APTV) technique is introduced. Average particle z position determination errors of the technique are as low as 0.33%, with a measurement depth of 40 mm. These accuracies show APTV's ability of measuring volumetric velocity fields in macroscopic domains with limited optical access.
Relaxation to equilibrium of the expectation values in macroscopic quantum systems.
Monnai, Takaaki
2011-07-01
A quantum mechanical explanation of the relaxation to equilibrium is shown for macroscopic systems for nonintegrable cases and numerically verified. The macroscopic system is initially in an equilibrium state, subsequently externally perturbed during a finite time, and then isolated for a sufficiently long time. We show a quantitative explanation that the initial microcanonical state typically reaches a state whose expectation values are well approximated by the average over another microcanonical ensemble.
Buckling of regular, chiral and hierarchical honeycombs under a general macroscopic stress state
Haghpanah, Babak; Papadopoulos, Jim; Mousanezhad, Davood; Nayeb-Hashemi, Hamid; Vaziri, Ashkan
2014-01-01
An approach to obtain analytical closed-form expressions for the macroscopic ‘buckling strength’ of various two-dimensional cellular structures is presented. The method is based on classical beam-column end-moment behaviour expressed in a matrix form. It is applied to sample honeycombs with square, triangular and hexagonal unit cells to determine their buckling strength under a general macroscopic in-plane stress state. The results were verified using finite-element Eigenvalue analysis. PMID:25002823
NASA Astrophysics Data System (ADS)
Sarfraz, M.; Saeed, Sundas; Yoon, P. H.; Abbas, G.; Shah, H. A.
2016-10-01
Spacecraft observations made near 1 AU show that both core and halo solar wind electrons exhibit temperature anisotropies that appear to be regulated by marginal electromagnetic electron cyclotron instability condition. In the literature, the threshold conditions of this instability, operative for T⊥>T∥, have been expressed as an inverse correlation between the temperature anisotropy, T⊥/T∥, and parallel beta, β∥, but such a relation was deduced on the basis of linear stability analysis combined with empirical fitting. The present paper, on the other hand, employs macroscopic quasi-linear analysis for core-halo two-component model of the solar wind electrons, in order to follow the self-consistent time history of the core and halo temperature development as well as the dynamics of magnetic field perturbation wave energy. In the present analysis, the inverse correlation for core and halo temperature anisotropy and parallel beta naturally emerges from the solutions of self-consistent theory. The present findings indicate that the macroscopic quasi-linear method may be useful for modeling the dynamics of solar wind electrons.
NASA Astrophysics Data System (ADS)
Galanti, Marta; Fanelli, Duccio; Piazza, Francesco
2016-08-01
Describing particle transport at the macroscopic or mesoscopic level in non-ideal environments poses fundamental theoretical challenges in domains ranging from inter and intra-cellular transport in biology to diffusion in porous media. Yet, often the nature of the constraints coming from many-body interactions or reflecting a complex and confining environment are better understood and modeled at the microscopic level. In this paper we review the subtle link between microscopic exclusion processes and the mean-field equations that ensue from them in the continuum limit. We show that in an inhomogeneous medium, i.e. when jumps are controlled by site-dependent hopping rates, one can obtain three different nonlinear advection-diffusion equations in the continuum limit, suitable for describing transport in the presence of quenched disorder and external fields, depending on the particular rule embodying site inequivalence at the microscopic level. In a situation that might be termed point-like scenario, when particles are treated as point-like objects, the effect of crowding as imposed at the microscopic level manifests in the mean-field equations only if some degree of inhomogeneity is enforced into the model. Conversely, when interacting agents are assigned a finite size, under the more realistic extended crowding framework, exclusion constraints persist in the unbiased macroscopic representation.
Ren, Li; Yang, Pengfei; Wang, Zhe; Zhang, Jian; Ding, Chong; Shang, Peng
2015-10-01
Bones with complicated hierarchical configuration and microstructures constitute the load-bearing system. Mechanical loading plays an essential role in maintaining bone health and regulating bone mechanical adaptation (modeling and remodeling). The whole-bone or sub-region (macroscopic) mechanical signals, including locomotion-induced loading and external actuator-generated vibration, ultrasound, oscillatory skeletal muscle stimulation, etc., give rise to sophisticated and distinct biomechanical and biophysical environments at the pericellular (microscopic) and collagen/mineral molecular (nanoscopic) levels, which are the direct stimulations that positively influence bone adaptation. While under microgravity, the stimulations decrease or even disappear, which exerts a negative influence on bone adaptation. A full understanding of the biomechanical and biophysical environment at different levels is necessary for exploring bone biomechanical properties and mechanical adaptation. In this review, the mechanical transferring theories from the macroscopic to the microscopic and nanoscopic levels are elucidated. First, detailed information of the hierarchical structures and biochemical composition of bone, which are the foundations for mechanical signal propagation, are presented. Second, the deformation feature of load-bearing bone during locomotion is clarified as a combination of bending and torsion rather than simplex bending. The bone matrix strains at microscopic and nanoscopic levels directly induced by bone deformation are critically discussed, and the strain concentration mechanism due to the complicated microstructures is highlighted. Third, the biomechanical and biophysical environments at microscopic and nanoscopic levels positively generated during bone matrix deformation or by dynamic mechanical loadings induced by external actuators, as well as those negatively affected under microgravity, are systematically discussed, including the interstitial fluid flow
NASA Astrophysics Data System (ADS)
Avolio, M. V.; Crisci, G. M.; D'Ambrosio, D.; di Gregorio, S.; Iovine, G.; Rongo, R.; Spataro, W.
Cellular Automata (CA) are able to capture the peculiar characteristics of systems, whose global evolution can be exclusively described on the basis of local interactions among their constituent parts ("a-centrism"). Such systems match the paradigm of parallelism with the a-centrism one. In modelling complex phenomena by means of classical CA, elementary automata characterised by few states and simple transition function have usually been involved. On the other hand, many complex macroscopic phenomena (even though characterised by properties of parallelism and a-centrism) can be very difficult to be modelled through classical CA, because of their hetero- geneous characteristics, which require a very large number of states. For such cases, which perfectly fit the general definition of CA, more complex transition rules (differ- ing from typical transition functions) would be, in fact, needed. Aiming at modelling these latter phenomena, an empirical method has been developed, based on the decom- position of the phenomenon into "elementary" components, whose behaviour can be described through local rules. Furthermore, criteria and conditions have been defined, in order to translate the local rules into a transition function, as needed for perform- ing cellular automata simulations. Applications of CA models to real cases of study have recently been attempted: landslides (earth flows, rock avalanches, debris flows), lava flows, soil erosion, soil contamination and bioremediation, forest fires have all been analysed through CA simulations, and encouraging results have been obtained. In the present paper, examples of application of the method for hazard evaluation are described, with particular reference to the Sarno 1998 debris flows and the Etna 2001 lava flows.
Bauer, Christina T; Kroner, Elmar; Fleck, Norman A; Arzt, Eduard
2015-10-23
Nature uses hierarchical fibrillar structures to mediate temporary adhesion to arbitrary substrates. Such structures provide high compliance such that the flat fibril tips can be better positioned with respect to asperities of a wavy rough substrate. We investigated the buckling and adhesion of hierarchically structured adhesives in contact with flat smooth, flat rough and wavy rough substrates. A macroscopic model for the structural adhesive was fabricated by molding polydimethylsiloxane into pillars of diameter in the range of 0.3-4.8 mm, with up to three different hierarchy levels. Both flat-ended and mushroom-shaped hierarchical samples buckled at preloads one quarter that of the single level structures. We explain this behavior by a change in the buckling mode; buckling leads to a loss of contact and diminishes adhesion. Our results indicate that hierarchical structures can have a strong influence on the degree of adhesion on both flat and wavy substrates. Strategies are discussed that achieve highly compliant substrates which adhere to rough substrates.
Jin, Haibao; Huang, Wei; Zheng, Yongli; Zhou, Yongfeng; Yan, Deyue
2012-07-09
Vesicle-vesicle aggregation to mimic cell-cell aggregation has attracted much attention. Here, hyperbranched polymer vesicles (branched-polymersomes, BPs) with a cell-like size were selected as model membranes, and the vesicle aggregation process, triggered by click chemistry of the copper-catalysed azide-alkyne cycloaddition reaction, was systematically studied. For this purpose, azide and alkynyl groups were loaded on the membranes of BPs through the co-assembly method to obtain N(3)-BPs and Alk-BPs, respectively. Subsequently, macroscopic vesicle aggregates were obtained when these two kinds of functional BPs were mixed together with the ratio of azide to alkynyl groups of about 1:1. Both the vesicle fusion events and lateral phase separation on the vesicle membrane occurred during such a vesicle aggregation process, and the fusion rate and phase-separation degree could be controlled by adjusting the clickable group content. The vesicle aggregation process with N(3) -micelles as desmosome mimics to connect with Alk-BPs through click-chemistry reaction was also studied, and large-scale vesicle aggregates without vesicle fusion were obtained in this process. The present work has extended the controllable cytomimetic vesicle aggregation process with the use of covalent bonds, instead of noncovalent bonds, as the driving force.
NASA Astrophysics Data System (ADS)
Yan, Fei; Tian, Fuli; Shi, Zhongke
2016-10-01
Urban traffic flows are inherently repeated on a daily or weekly basis. This repeatability can help improve the traffic conditions if it is used properly by the control system. In this paper, we propose a novel iterative learning control (ILC) strategy for traffic signals of urban road networks using the repeatability feature of traffic flow. To improve the control robustness, the ILC strategy is further integrated with an error feedback control law in a complementary manner. Theoretical analysis indicates that the ILC-based traffic signal control methods can guarantee the asymptotic learning convergence, despite the presence of modeling uncertainties and exogenous disturbances. Finally, the impacts of the ILC-based signal control strategies on the network macroscopic fundamental diagram (MFD) are examined. The results show that the proposed ILC-based control strategies can homogenously distribute the network accumulation by controlling the vehicle numbers in each link to the desired levels under different traffic demands, which can result in the network with high capacity and mobility.
Cox, Stephen J; Raza, Zamaan; Kathmann, Shawn M; Slater, Ben; Michaelides, Angelos
2013-01-01
It is surprisingly difficult to freeze water. Almost all ice that forms under "mild" conditions (temperatures > -40 degrees C) requires the presence of a nucleating agent--a solid particle that facilitates the freezing process--such as clay mineral dust, soot or bacteria. In a computer simulation, the presence of such ice nucleating agents does not necessarily alleviate the difficulties associated with forming ice on accessible timescales. Nevertheless, in this work we present results from molecular dynamics simulations in which we systematically compare homogeneous and heterogeneous ice nucleation, using the atmospherically important clay mineral kaolinite as our model ice nucleating agent. From our simulations, we do indeed find that kaolinite is an excellent ice nucleating agent but that contrary to conventional thought, non-basal faces of ice can nucleate at the basal face of kaolinite. We see that in the liquid phase, the kaolinite surface has a drastic effect on the density profile of water, with water forming a dense, tightly bound first contact layer. Monitoring the time evolution of the water density reveals that changes away from the interface may play an important role in the nucleation mechanism. The findings from this work suggest that heterogeneous ice nucleating agents may not only enhance the ice nucleation rate, but also alter the macroscopic structure of the ice crystals that form.
Carreón-Calderón, Bernardo
2012-10-14
Stability analysis is generally used to verify that the solution to phase equilibrium calculations corresponds to a stable state (minimum of the free energy). In this work, tangent plane distance analysis for stability of macroscopic mixtures is also used for analyzing the nucleation process, reconciling thus this analysis with classical nucleation theories. In the context of the revised nucleation theory, the driving force and the nucleation work are expressed as a function of the Lagrange multiplier corresponding to the mole fraction constraint from the minimization problem of stability analysis. Using a van der Waals fluid applied to a ternary mixture, Lagrange multiplier properties are illustrated. In particular, it is shown how the Lagrange multiplier value is equal to one on the binodal and spinodal curves at the same time as the driving force of nucleation vanishes on these curves. Finally, it is shown that, on the spinodal curve, the nucleation work from the revised and generalized nucleation theories are characterized by two different local minima from stability analysis, irrespective of any interfacial tension models.
Macroscopic spatial analysis of pedestrian and bicycle crashes.
Siddiqui, Chowdhury; Abdel-Aty, Mohamed; Choi, Keechoo
2012-03-01
This study investigates the effect of spatial correlation using a Bayesian spatial framework to model pedestrian and bicycle crashes in Traffic Analysis Zones (TAZs). Aggregate models for pedestrian and bicycle crashes were estimated as a function of variables related to roadway characteristics, and various demographic and socio-economic factors. It was found that significant differences were present between the predictor sets for pedestrian and bicycle crashes. The Bayesian Poisson-lognormal model accounting for spatial correlation for pedestrian crashes in the TAZs of the study counties retained nine variables significantly different from zero at 95% Bayesian credible interval. These variables were - total roadway length with 35 mph posted speed limit, total number of intersections per TAZ, median household income, total number of dwelling units, log of population per square mile of a TAZ, percentage of households with non-retired workers but zero auto, percentage of households with non-retired workers and one auto, long term parking cost, and log of total number of employment in a TAZ. A separate distinct set of predictors were found for the bicycle crash model. In all cases the Bayesian models with spatial correlation performed better than the models that did not account for spatial correlation among TAZs. This finding implies that spatial correlation should be considered while modeling pedestrian and bicycle crashes at the aggregate or macro-level.
Poloski, Adam P.; Daniel, Richard C.; Rector, David R.; Bredt, Paul R.; Buck, Edgar C.; Berg, John C.; Saez, Avelino E.
2006-09-29
Hanford TRU tank sludges are complex mixtures of undissolved minerals and salt solids in an aqueous phase of high ionic strength. They show complex rheological behavior resulting from interactions at the macroscopic level, such as interparticle friction between grains in the coarse fraction, as well as from interactions at the nano-scale level, such as the agglomeration of colloidal particles. An understanding of how phenomena such as interparticle friction and aggregate stability under shear will allow better control of Hanford TRU tank sludges being processed for disposal. The project described in this report had two objectives. The first was to understand the physical properties and behavior of the Hanford transuranic (TRU) tank sludges under conditions that might exist during retrieval, treatment, packaging, and transportation for disposal at the Waste Isolation Pilot Plant (WIPP). The second objective was to develop a fundamental understanding of sludge physical properties by correlating the macroscopic behavior with interactions occurring at the particle/colloidal scale. These objectives were accomplished by: 1) developing continuum models for coarse granular slurries and 2) studying the behavior of colloidal agglomerates under shear and under irradiation.
Thermal Equilibrium of a Macroscopic Quantum System in a Pure State
NASA Astrophysics Data System (ADS)
Goldstein, Sheldon; Huse, David A.; Lebowitz, Joel L.; Tumulka, Roderich
2015-09-01
We consider the notion of thermal equilibrium for an individual closed macroscopic quantum system in a pure state, i.e., described by a wave function. The macroscopic properties in thermal equilibrium of such a system, determined by its wave function, must be the same as those obtained from thermodynamics, e.g., spatial uniformity of temperature and chemical potential. When this is true we say that the system is in macroscopic thermal equilibrium (MATE). Such a system may, however, not be in microscopic thermal equilibrium (MITE). The latter requires that the reduced density matrices of small subsystems be close to those obtained from the microcanonical, equivalently the canonical, ensemble for the whole system. The distinction between MITE and MATE is particularly relevant for systems with many-body localization for which the energy eigenfuctions fail to be in MITE while necessarily most of them, but not all, are in MATE. We note, however, that for generic macroscopic systems, including those with MBL, most wave functions in an energy shell are in both MATE and MITE. For a classical macroscopic system, MATE holds for most phase points on the energy surface, but MITE fails to hold for any phase point.
Zhu, Zhongcheng; Li, Yang; Xu, Hui; Peng, Xin; Chen, Ya-Nan; Shang, Cong; Zhang, Qin; Liu, Jiaqi; Wang, Huiliang
2016-06-22
Bulk graphene oxide (GO) nanocomposite materials with macroscopically oriented GO liquid crystalline (LC) structures exhibit interesting anisotropic properties, but their facile preparations remain challenging. This work reports for the first time the facile preparation of poly(N-isopropylacrylamide) (PNIPAM)/GO nanocomposite hydrogels with macroscopically oriented LC structures with the assistance of a flow field induced by vacuum degassing and the in situ polymerization accelerated by GO. The hydrogel prepared with a GO concentration of 5.0 mg mL(-1) exhibits macroscopically aligned LC structures, which endow the gels with anisotropic optical, mechanical properties, and dimensional changes during the phase transition. The hydrogels show dramatically enhanced tensile mechanical properties and phase transition rates. The oriented LC structures are not damaged during the phase transition of the PNIPAM/GO hydrogels, and hence their LC behavior undergoes reversible change. Moreover, highly oriented LC structures can also be formed when the gels are elongated, even for the gels which do not have macroscopically oriented LC structures. Very impressively, the oriented LC structures in the hydrogels can be permanently maintained by drying the gel samples elongated to and then kept at a constant tensile strain. The thermosensitive nature of PNIPAM and the angle-dependent nature of the macroscopically aligned GO LC structures allow the practical applications of the PNIPAM/GO hydrogels as optical switches, soft sensors, and actuators and so on.
Thermal Equilibrium of a Macroscopic Quantum System in a Pure State.
Goldstein, Sheldon; Huse, David A; Lebowitz, Joel L; Tumulka, Roderich
2015-09-04
We consider the notion of thermal equilibrium for an individual closed macroscopic quantum system in a pure state, i.e., described by a wave function. The macroscopic properties in thermal equilibrium of such a system, determined by its wave function, must be the same as those obtained from thermodynamics, e.g., spatial uniformity of temperature and chemical potential. When this is true we say that the system is in macroscopic thermal equilibrium (MATE). Such a system may, however, not be in microscopic thermal equilibrium (MITE). The latter requires that the reduced density matrices of small subsystems be close to those obtained from the microcanonical, equivalently the canonical, ensemble for the whole system. The distinction between MITE and MATE is particularly relevant for systems with many-body localization for which the energy eigenfuctions fail to be in MITE while necessarily most of them, but not all, are in MATE. We note, however, that for generic macroscopic systems, including those with MBL, most wave functions in an energy shell are in both MATE and MITE. For a classical macroscopic system, MATE holds for most phase points on the energy surface, but MITE fails to hold for any phase point.
A microscale model of bacterial and biofilm dynamics in porous media.
Dillon, R; Fauci, L
2000-06-05
A microscale model for the transport and coupled reaction of microbes and chemicals in an idealized two-dimensional porous media has been developed. This model includes the flow, transport, and bioreaction of nutrients, electron acceptors, and microbial cells in a saturated granular porous media. The fluid and chemicals are represented as a continuum, but the bacterial cells and solid granular particles are represented discretely. Bacterial cells can attach to the particle surfaces or be advected in the bulk fluid. The bacterial cells can also be motile and move preferentially via a run and tumble mechanism toward a chemoattractant. The bacteria consume oxygen and nutrients and alter the profiles of these chemicals. Attachment of bacterial cells to the soil matrix and growth of bacteria can change the local permeability. The coupling of mass transport and bioreaction can produce spatial gradients of nutrients and electron acceptor concentrations. We describe a numerical method for the microscale model, show results of a convergence study, and present example simulations of the model system.
On the emergence of macroscopic transport barriers from staircase structures
NASA Astrophysics Data System (ADS)
Ashourvan, Arash; Diamond, P. H.
2017-01-01
This paper presents a theory for the formation and evolution of coupled density staircases and zonal shear profiles in a simple model of drift-wave turbulence. Density, vorticity, and fluctuation potential enstrophy are the fields evolved in this system. Formation of staircase structures is due to inhomogeneous mixing of generalized potential vorticity (PV), resulting in the sharpening of density and vorticity gradients in some regions, and weakening them in others. When the PV gradients steepen, the density staircase structure develops into a lattice of mesoscale "jumps," and "steps," which are, respectively, the regions of local gradient steepening and flattening. The jumps merge and migrate in radius, leading to the development of macroscale profile structures from mesoscale elements. The positive feedback process, which drives the staircase formation occurs via a Rhines scale dependent mixing length. We present extensive studies of bifurcation physics of the global state, including results on the global flux-gradient relations (flux landscapes) predicted by the model. Furthermore, we demonstrate that, depending on the sources and boundary conditions, either a region of enhanced confinement, or a region with strong turbulence can form at the edge. This suggests that the profile self-organization is a global process, though one which can be described by a local, but nonlinear model. This model is the first to demonstrate how the mesoscale condensation of staircases leads to global states of enhanced confinement.
Active traffic management on road networks: a macroscopic approach.
Kurzhanskiy, Alex A; Varaiya, Pravin
2010-10-13
Active traffic management (ATM) is the ability to dynamically manage recurrent and non-recurrent congestion based on prevailing traffic conditions in order to maximize the effectiveness and efficiency of road networks. It is a continuous process of (i) obtaining and analysing traffic measurement data, (ii) operations planning, i.e. simulating various scenarios and control strategies, (iii) implementing the most promising control strategies in the field, and (iv) maintaining a real-time decision support system that filters current traffic measurements to predict the traffic state in the near future, and to suggest the best available control strategy for the predicted situation. ATM relies on a fast and trusted traffic simulator for the rapid quantitative assessment of a large number of control strategies for the road network under various scenarios, in a matter of minutes. The open-source macrosimulation tool Aurora ROAD NETWORK MODELER is a good candidate for this purpose. The paper describes the underlying dynamical traffic model and what it takes to prepare the model for simulation; covers the traffic performance measures and evaluation of scenarios as part of operations planning; introduces the framework within which the control strategies are modelled and evaluated; and presents the algorithm for real-time traffic state estimation and short-term prediction.
The effect of interlayer adhesion on the mechanical behaviors of macroscopic graphene oxide papers.
Gao, Yun; Liu, Lu-Qi; Zu, Sheng-Zhen; Peng, Ke; Zhou, Ding; Han, Bao-Hang; Zhang, Zhong
2011-03-22
High mechanical performances of macroscopic graphene oxide (GO) papers are attracting great interest owing to their merits of lightweight and multiple functionalities. However, the loading role of individual nanosheets and its effect on the mechanical properties of the macroscopic GO papers are not yet well understood. Herein, we effectively tailored the interlayer adhesions of the GO papers by introducing small molecules, that is, glutaraldehyde (GA) and water molecules, into the gallery regions. With the help of in situ Raman spectroscopy, we compared the varied load-reinforcing roles of nanosheets, and further predicted the Young's moduli of the GO papers. Systematic mechanical tests have proven that the enhancement of the tensile modulus and strength of the GA-treated GO paper arose from the improved load-bearing capability of the nanosheets. On the basis of Raman and macroscopic mechanical tests, the influences of interlayer adhesions on the fracture mechanisms of the strained GO papers were inferred.
A strict experimental test of macroscopic realism in a superconducting flux qubit
NASA Astrophysics Data System (ADS)
Knee, George C.; Kakuyanagi, Kosuke; Yeh, Mao-Chuang; Matsuzaki, Yuichiro; Toida, Hiraku; Yamaguchi, Hiroshi; Saito, Shiro; Leggett, Anthony J.; Munro, William J.
2016-11-01
Macroscopic realism is the name for a class of modifications to quantum theory that allow macroscopic objects to be described in a measurement-independent manner, while largely preserving a fully quantum mechanical description of the microscopic world. Objective collapse theories are examples which aim to solve the quantum measurement problem through modified dynamical laws. Whether such theories describe nature, however, is not known. Here we describe and implement an experimental protocol capable of constraining theories of this class, that is more noise tolerant and conceptually transparent than the original Leggett-Garg test. We implement the protocol in a superconducting flux qubit, and rule out (by ~84 s.d.) those theories which would deny coherent superpositions of 170 nA currents over a ~10 ns timescale. Further, we address the `clumsiness loophole' by determining classical disturbance with control experiments. Our results constitute strong evidence for the superposition of states of nontrivial macroscopic distinctness.
NASA Astrophysics Data System (ADS)
Carlisle, Andrew; Kwon, Hyukjoon; Jeong, Hyunseok; Ferraro, Alessandro; Paternostro, Mauro
2015-08-01
Optomechanics is currently believed to provide a promising route towards the achievement of genuine quantum effects at the large, massive-system scale. By using a recently proposed figure of merit that is well suited to address continuous-variable systems, in this paper we analyze the requirements needed for the state of a mechanical mode (embodied by an end-cavity cantilever or a membrane placed within an optical cavity) to be qualified as macroscopic. We show that according to the phase-space-based criterion that we have chosen for our quantitative analysis, the state achieved through strong single-photon radiation-pressure coupling to a quantized field of light and conditioned by measurements operated on the latter might be interpreted as macroscopically quantum. In general, though, genuine macroscopic quantum superpositions appear to be possible only under quite demanding experimental conditions.
Hybrid methods for witnessing entanglement in a microscopic-macroscopic system
Spagnolo, Nicolo; Vitelli, Chiara; Paternostro, Mauro; De Martini, Francesco; Sciarrino, Fabio
2011-09-15
We propose a hybrid approach to the experimental assessment of the genuine quantum features of a general system consisting of microscopic and macroscopic parts. We infer entanglement by combining dichotomic measurements on a bidimensional system and phase-space inference through the Wigner distribution associated with the macroscopic component of the state. As a benchmark, we investigate the feasibility of our proposal in a bipartite-entangled state composed of a single-photon and a multiphoton field. Our analysis shows that, under ideal conditions, maximal violation of a Clauser-Horne-Shimony-Holt-based inequality is achievable regardless of the number of photons in the macroscopic part of the state. The difficulty in observing entanglement when losses and detection inefficiency are included can be overcome by using a hybrid entanglement witness that allows efficient correction for losses in the few-photon regime.
Correlations between Nanoindentation Hardness and Macroscopic Mechanical Properties in DP980 Steels
Taylor, Mark D.; Choi, Kyoo Sil; Sun, Xin; Matlock, David K.; Packard, Corrine; Xu, Le; Barlat, Frederic
2014-03-01
Multiphase advanced high strength steels (AHSS) are being increasingly used in the automotive industry due to their low cost, good availability and excellent combination of strength and ductility. There is a keen interest from the automotive and steel industry for more fundamental understandings on the key microstructure features influencing the macroscopic properties, i.e., tensile properties, hole-expansion ratio and localized formability of AHSS. In this study, the micro- and macro-level properties for eight commercial DP980 steels are first characterized and quantified with various experimental methods. Correlations between macroscopic-level properties and relationships between various micro- and macro- properties for these steels are then established based on the experimental measurements. It is found that, despite their differences in their chemistry, processing parameters and sheet thickness, the eight DP980 steels do have common microstructural level properties governing their specific macroscopic properties in terms of strength, elongation and hole expansion performance.
A strict experimental test of macroscopic realism in a superconducting flux qubit.
Knee, George C; Kakuyanagi, Kosuke; Yeh, Mao-Chuang; Matsuzaki, Yuichiro; Toida, Hiraku; Yamaguchi, Hiroshi; Saito, Shiro; Leggett, Anthony J; Munro, William J
2016-11-04
Macroscopic realism is the name for a class of modifications to quantum theory that allow macroscopic objects to be described in a measurement-independent manner, while largely preserving a fully quantum mechanical description of the microscopic world. Objective collapse theories are examples which aim to solve the quantum measurement problem through modified dynamical laws. Whether such theories describe nature, however, is not known. Here we describe and implement an experimental protocol capable of constraining theories of this class, that is more noise tolerant and conceptually transparent than the original Leggett-Garg test. We implement the protocol in a superconducting flux qubit, and rule out (by ∼84 s.d.) those theories which would deny coherent superpositions of 170 nA currents over a ∼10 ns timescale. Further, we address the 'clumsiness loophole' by determining classical disturbance with control experiments. Our results constitute strong evidence for the superposition of states of nontrivial macroscopic distinctness.
A macroscopic plasma Lagrangian and its application to wave interactions and resonances
NASA Technical Reports Server (NTRS)
Peng, Y. K. M.
1974-01-01
The derivation of a macroscopic plasma Lagrangian is considered, along with its application to the description of nonlinear three-wave interaction in a homogeneous plasma and linear resonance oscillations in a inhomogeneous plasma. One approach to obtain the Lagrangian is via the inverse problem of the calculus of variations for arbitrary first and second order quasilinear partial differential systems. Necessary and sufficient conditions for the given equations to be Euler-Lagrange equations of a Lagrangian are obtained. These conditions are then used to determine the transformations that convert some classes of non-Euler-Lagrange equations to Euler-Lagrange equation form. The Lagrangians for a linear resistive transmission line and a linear warm collisional plasma are derived as examples. Using energy considerations, the correct macroscopic plasma Lagrangian is shown to differ from the velocity-integrated low Lagrangian by a macroscopic potential energy that equals twice the particle thermal kinetic energy plus the energy lost by heat conduction.
NASA Astrophysics Data System (ADS)
Milton, Graeme Walter
2013-07-01
A complete characterization is given of the possible macroscopic deformations of periodic non-linear affine unimode metamaterials constructed from rigid bars and pivots. The materials are affine in the sense that their macroscopic deformations can only be affine deformations: on a local level the deformation may vary from cell to cell. Unimode means that macroscopically the material can only deform along a one dimensional trajectory in the six dimensional space of invariants describing the deformation (excluding translations and rotations). We show by explicit construction that any continuous trajectory is realizable to an arbitrarily high degree of approximation provided at all points along the trajectory the geometry does not collapse to a lower dimensional one. In particular, we present two and three dimensional dilational materials having an arbitrarily large flexibility window. These are perfect auxetic materials for which a dilation is the only easy mode of deformation. They are free to dilate to arbitrarily large strain with zero bulk modulus.
Graphene-based macroscopic assemblies and architectures: an emerging material system.
Cong, Huai-Ping; Chen, Jia-Fu; Yu, Shu-Hong
2014-11-07
Due to the outstanding physicochemical properties arising from its truly two-dimensional (2D) planar structure with a single-atom thickness, graphene exhibits great potential for use in sensors, catalysts, electrodes, and in biological applications, etc. With further developments in the theoretical understanding and assembly techniques, graphene should enable great changes both in scientific research and practical industrial applications. By the look of development, it is of fundamental and practical significance to translate the novel physical and chemical properties of individual graphene nanosheets into the macroscale by the assembly of graphene building blocks into macroscopic architectures with structural specialities and functional novelties. The combined features of a 2D planar structure and abundant functional groups of graphene oxide (GO) should provide great possibilities for the assembly of GO nanosheets into macroscopic architectures with different macroscaled shapes through various assembly techniques under different bonding interactions. Moreover, macroscopic graphene frameworks can be used as ideal scaffolds for the incorporation of functional materials to offset the shortage of pure graphene in the specific desired functionality. The advantages of light weight, supra-flexibility, large surface area, tough mechanical strength, and high electrical conductivity guarantee graphene-based architectures wide application fields. This critical review mainly addresses recent advances in the design and fabrication of graphene-based macroscopic assemblies and architectures and their potential applications. Herein, we first provide overviews of the functional macroscopic graphene materials from three aspects, i.e., 1D graphene fibers/ribbons, 2D graphene films/papers, 3D network-structured graphene monoliths, and their composite counterparts with either polymers or nano-objects. Then, we present the promising potential applications of graphene-based macroscopic
Sanz-Prat, Alicia; Lu, Chuanhe; Amos, Richard T; Finkel, Michael; Blowes, David W; Cirpka, Olaf A
2016-09-01
the two types of biomass at late times. Results obtained by mapping the exposure-time based results to the two-dimensional domain are compared with simulations based on the two-dimensional, spatially explicit advection-dispersion-reaction equation. Once quasi-steady state has been reached, we find a good agreement in terms of the chemical-compound concentrations between the two approaches inside the reactive zones, whereas the exposure-time based model is not able to capture reactions occurring in the zones with zero electron-donor release. We conclude that exposure-time models provide good approximations of nonlinear bio-reactive transport when transverse mixing is not the overall controlling process and all reactions are essentially restricted to distinct reactive zones.
NASA Astrophysics Data System (ADS)
Sanz-Prat, Alicia; Lu, Chuanhe; Amos, Richard T.; Finkel, Michael; Blowes, David W.; Cirpka, Olaf A.
2016-09-01
the two types of biomass at late times. Results obtained by mapping the exposure-time based results to the two-dimensional domain are compared with simulations based on the two-dimensional, spatially explicit advection-dispersion-reaction equation. Once quasi-steady state has been reached, we find a good agreement in terms of the chemical-compound concentrations between the two approaches inside the reactive zones, whereas the exposure-time based model is not able to capture reactions occurring in the zones with zero electron-donor release. We conclude that exposure-time models provide good approximations of nonlinear bio-reactive transport when transverse mixing is not the overall controlling process and all reactions are essentially restricted to distinct reactive zones.
Albéric, Marie; Dean, Mason N.; Gourrier, Aurélien; Wagermaier, Wolfgang; Dunlop, John W. C.; Staude, Andreas; Fratzl, Peter; Reiche, Ina
2017-01-01
Macroscopic, periodic, dark and bright patterns are observed on sections of elephant tusk, in the dentin part (ivory). The motifs—also called Schreger pattern—vary depending on the orientation in the tusk: on sections perpendicular to the tusk axis, a checkerboard pattern is present whereas on sections longitudinal to it, alternating stripes are observed. This pattern has been used to identify elephant and mammoth ivory in archeological artifacts and informs on the continuous tissue growth mechanisms of tusk. However, its origin, assumed to be related to the 3D structure of empty microtubules surrounded by the ivory matrix has yet to be characterized unequivocally. Based on 2D observations of the ivory microtubules by means of a variety of imaging techniques of three different planes (transverse, longitudinal and tangential to the tusk axis), we show that the dark areas of the macroscopic pattern are due to tubules oblique to the surface whereas bright areas are related to tubules parallel to it. The different microstructures observed in the three planes as well as the 3D data obtained by SR-μCT analysis allow us to propose a 3D model of the microtubule network with helical tubules phase-shifted in the tangential direction. The phase shift is a combination of a continuous phase shift of π every 1 mm with a stepwise phase shift of π/2 every 500 μm. By using 3D modeling, we show how the 3D helical model better represents the experimental microstructure observed in 2D planes compared to previous models in the literature. This brings new information on the origin of the unique Schreger pattern of elephant ivory, crucial for better understanding how archaeological objects were processed and for opening new routes to rethink how biological materials are built. PMID:28125603
Position-Momentum Uncertainty Relation for an Open Macroscopic Quantum System
NASA Astrophysics Data System (ADS)
Naeij, Hamid Reza; Shafiee, Afshin
2016-12-01
The macroscopic quantum systems are considered as a bridge between quantum and classical systems. In this study, we explore the validity of the original Heisenberg position-momentum uncertainty relation for a macroscopic harmonic oscillator interacting with environmental micro-particles. Our results show that, in the quasi-classical situation, the original uncertainty relation does not hold, when the number of particles in the environment is small. Nonetheless, increasing the environmental degrees of freedom removes the violation bounds in the regions of our investigation.
Metastable states and macroscopic quantum tunneling in a cold atom josephson ring
Solenov, Dmitry; Mozyrsky, Dmitry
2009-01-01
We study macroscopic properties of a system of weakly interacting neutral bosons confined in a ring-shaped potential with a Josephson junction. We derive an effective low energy action for this system and evaluate its properties. In particular we find that the system possesses a set of metastable current-carrying states and evaluate the rates of transitions between these states due to macroscopic quantum tunneling. Finally we discuss signatures of different metastable states in the time-of-flight images and argue that the effect is observable within currently available experimental technique.
Departure of microscopic friction from macroscopic drag in molecular fluid dynamics
NASA Astrophysics Data System (ADS)
Hanasaki, Itsuo; Fujiwara, Daiki; Kawano, Satoyuki
2016-03-01
Friction coefficient of the Langevin equation and drag of spherical macroscopic objects in steady flow at low Reynolds numbers are usually regarded as equivalent. We show that the microscopic friction can be different from the macroscopic drag when the mass is taken into account for particles with comparable scale to the surrounding fluid molecules. We illustrate it numerically by molecular dynamics simulation of chloride ion in water. Friction variation by the atomistic mass effect beyond the Langevin regime can be of use in the drag reduction technology as well as the electro or thermophoresis.
Addressing a single spin in diamond with a macroscopic dielectric microwave cavity
Le Floch, J.-M.; Tobar, M. E.; Bradac, C.; Nand, N.; Volz, T.; Castelletto, S.
2014-09-29
We present a technique for addressing single nitrogen-vacancy (NV) center spins in diamond over macroscopic distances using a tunable dielectric microwave cavity. We demonstrate optically detected magnetic resonance (ODMR) for a single negatively charged NV center (NV{sup –}) in a nanodiamond (ND) located directly under the macroscopic microwave cavity. By moving the cavity relative to the ND, we record the ODMR signal as a function of position, mapping out the distribution of the cavity magnetic field along one axis. In addition, we argue that our system could be used to determine the orientation of the NV{sup –} major axis in a straightforward manner.
de Rijcke, Sarah
2008-01-01
It is often argued that photography's scientific inauguration meaningfully coincided with a shift towards the ideal of mechanical objectivity. Values of disinterestedness and precision were readily attributed to photography and were cherished by the emerging field of neurology as well. However, after the publication of the first neuroanatomical atlas to contain photographs, Jules Bernard Luys' Iconographie Photographique des Centres Nerveux (1873), the use of photography in macroscopic neuroanatomy remained rare. The present article sketches this largely overlooked terrain of investigation and will expand on why in macroscopical neuroanatomy photography failed to offer a satisfactory alternative to drawing or engraving.
Vaidyanathan, T K; Schulman, A; Nielsen, J P; Shalita, S
1981-01-01
Radiographic analysis of uniform cylindrical castings fabricated by the centrifugal casting technique has revealed that the macroscopic porosity is dependent on the location of the sprue attachment to the casting. This is attributed to the significant pressure gradient associated with the centrifugal casting technique. The pressure gradient results in different heat transfer rates at portions of the castings near and away from the free surface of the button. Consequently, the macroscopic porosity is invariably at portions of the casting close to the free surface of the button. In addition, some optimized sprue-reservoir combinations could be predicted and proved, based on this pressure gradient concept.
NASA Astrophysics Data System (ADS)
Brand, Helmut R.; Cladis, P. E.; Pleiner, Harald
2009-03-01
Polar liquid crystalline phases are relevant for fluid liquid crystal phases observed in banana liquid crystals as well as for a class of polymeric liquid crystalline materials investigated recently. In this Brief Report we present the reversible dynamics for polar nematic liquid crystals with C∞v symmetry, where the macroscopic polarization representing polar order acts as an independent macroscopic variable. We find reversible coupling terms, for example, between flow and temperature and concentration gradients specific for the existence of a polar preferred direction. We suggest concrete experiments to check the importance of the reversible dynamic cross-coupling terms presented here.
Redox-responsive macroscopic gel assembly based on discrete dual interactions.
Nakahata, Masaki; Takashima, Yoshinori; Harada, Akira
2014-04-01
The macroscopic self-assembly of polymeric hydrogels modified with β-cyclodextrin (βCD gel), ferrocene (Fc gel), and styrenesulfonic acid sodium salt (SSNa gel) was investigated. Under reductive conditions, the Fc gel selectively adhered to the βCD gel through a host-guest interaction. On the other hand, the oxidized ferrocenium (Fc(+)) gel selectively adhered to the SSNa gel through an ionic interaction under oxidative conditions. The adhesion strength was estimated by a tensile test. We finally succeeded in forming an ABC-type macroscopic assembly of all three gels through two discrete noncovalent interactions.
a Macroscopic Analysis of Eddy Currents in Nonferrous Metals
NASA Astrophysics Data System (ADS)
Holder, Morris Eugene
1992-01-01
The original purpose of this research was to determine if the signals produced by the eddy currents induced into nonferrous metals as they pass through a static magnetic field could be used to distinguish between these metals. First, it was shown that for samples of the same size and shape, the maximum negative response produced by a Hall-effect sensor varied directly with the conductivity of the sample material. This was true for all shapes tested including rectangles, disks, rings, and cylinders. Samples of aluminum, brass, copper, lead, and zinc were easily distinguished from each other using the maximum negative response measured. The largest dimension of any sample tested was 4 inches, but algorithms could be developed for larger samples according to the statistics. The correlation coefficients for all sets of data collected in a randomized factorial design experiment were greater than 0.96. An algorithm was developed which correctly predicted the form of the response of the sensing apparatus to the passing of a thin copper ring through the static magnetic field. This involved writing an expression for the magnetic field produced by the eddy currents in the ring as the ring dropped from above, through, and beyond the static magnetic field. The inductive character of the nonferrous metals was incorporated into the model by introducing convolution. The currents produced by the induced emf were convolved with the residual decaying eddy currents to produce the net current. The model was responsive to the time constant associated with the conductivity, size, and shape of the samples. With convolution included, the simulated response produced by the model developed herein agreed well with the actual response measured. A new expression for the distribution of eddy currents in a nonferrous ring as it passes through a static magnetic field was developed to support the experimental findings. The new current distribution expression has the form of a fourth
Linking macroscopic with microscopic neuroanatomy using synthetic neuronal populations.
Schneider, Calvin J; Cuntz, Hermann; Soltesz, Ivan
2014-10-01
Dendritic morphology has been shown to have a dramatic impact on neuronal function. However, population features such as the inherent variability in dendritic morphology between cells belonging to the same neuronal type are often overlooked when studying computation in neural networks. While detailed models for morphology and electrophysiology exist for many types of single neurons, the role of detailed single cell morphology in the population has not been studied quantitatively or computationally. Here we use the structural context of the neural tissue in which dendritic trees exist to drive their generation in silico. We synthesize the entire population of dentate gyrus granule cells, the most numerous cell type in the hippocampus, by growing their dendritic trees within their characteristic dendritic fields bounded by the realistic structural context of (1) the granule cell layer that contains all somata and (2) the molecular layer that contains the dendritic forest. This process enables branching statistics to be linked to larger scale neuroanatomical features. We find large differences in dendritic total length and individual path length measures as a function of location in the dentate gyrus and of somatic depth in the granule cell layer. We also predict the number of unique granule cell dendrites invading a given volume in the molecular layer. This work enables the complete population-level study of morphological properties and provides a framework to develop complex and realistic neural network models.
Emergence of Macroscopic Transport Barriers from Staircase Structures
NASA Astrophysics Data System (ADS)
Ashourvan, Arash; Diamond, Patrick H.
2016-10-01
A theory is presented for the formation and evolution of coupled density staircases (SC) and zonal shear profiles in a simple model of drift-wave turbulence. Density, vorticity and fluctuation potential enstrophy are the fields evolved for this system. Formation of SC structures is due to inhomogeneous mixing of generalized potential vorticity (PV), resulting in the sharpening of density and vorticity gradients in some regions and weakening them in others. The positive feedback which drives SC formation is implemented via a Rhines scale dependent mixing length. When PV gradients steepen, the density SC structure develops into a lattice of mesoscale `jumps', and `steps', which are respectively, regions of local gradient steepening and flattening. The jumps merge and migrate in radius, leading to the development of macroscale profile structures from mesoscale elements. Furthermore, depending on the sources and boundary conditions, either a region of enhanced confinement, or a region with strong turbulence can form at the edge. We present extensive studies of bifurcation physics of the global state, including results on the flux-gradient landscapes. This model is the first to demonstrate how mesoscale condensation of SCs leads to global states of enhanced confinement. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, under Award Numbers DE-FG02-04ER54738 and DE-SC0008378.
Elastic rods with incompatible strain: Macroscopic versus microscopic buckling
NASA Astrophysics Data System (ADS)
Lestringant, Claire; Audoly, Basile
2017-06-01
We consider the buckling of a long prismatic elastic solid under the combined effect of a pre-stress that is inhomogeneous in the cross-section, and of a prescribed displacement of its endpoints. A linear bifurcation analysis is carried out using different structural models (namely a double beam, a rectangular thin plate, and a hyper-elastic prismatic solid in 3-d): it yields the buckling mode and the wavenumber qc that are first encountered when the end-to-end displacement is progressively decreased with fixed pre-stress. For all three structural models, we find a transition from a long-wavelength (qc = 0) to a short-wavelength first buckling mode (qc ≠ 0) when the inhomogeneous pre-stress is increased past a critical value. A method for calculating the critical inhomogeneous pre-stress is proposed based on a small-wavenumber expansion of the buckling mode. Overall, our findings explain the formation of multiple perversions in elastomer strips, as well as the large variations in the number of perversions as a function of pre-stress and cross-sectional geometry, as reported by Liu et al. (2014).
Linking Macroscopic with Microscopic Neuroanatomy Using Synthetic Neuronal Populations
Schneider, Calvin J.; Cuntz, Hermann; Soltesz, Ivan
2014-01-01
Dendritic morphology has been shown to have a dramatic impact on neuronal function. However, population features such as the inherent variability in dendritic morphology between cells belonging to the same neuronal type are often overlooked when studying computation in neural networks. While detailed models for morphology and electrophysiology exist for many types of single neurons, the role of detailed single cell morphology in the population has not been studied quantitatively or computationally. Here we use the structural context of the neural tissue in which dendritic trees exist to drive their generation in silico. We synthesize the entire population of dentate gyrus granule cells, the most numerous cell type in the hippocampus, by growing their dendritic trees within their characteristic dendritic fields bounded by the realistic structural context of (1) the granule cell layer that contains all somata and (2) the molecular layer that contains the dendritic forest. This process enables branching statistics to be linked to larger scale neuroanatomical features. We find large differences in dendritic total length and individual path length measures as a function of location in the dentate gyrus and of somatic depth in the granule cell layer. We also predict the number of unique granule cell dendrites invading a given volume in the molecular layer. This work enables the complete population-level study of morphological properties and provides a framework to develop complex and realistic neural network models. PMID:25340814
Brenner, Howard
2005-12-01
A quiescent single-component gravity-free gas subject to a small steady uniform temperature gradient T, despite being at rest, is shown to experience a drift velocity UD=-D* gradient ln T, where D* is the gas's nonisothermal self-diffusion coefficient. D* is identified as being the gas's thermometric diffusivity alpha. The latter differs from the gas's isothermal isotopic self-diffusion coefficient D, albeit only slightly. Two independent derivations are given of this drift velocity formula, one kinematical and the other dynamical, both derivations being strictly macroscopic in nature. Within modest experimental and theoretical uncertainties, this virtual drift velocity UD=-alpha gradient ln T is shown to be constitutively and phenomenologically indistinguishable from the well-known experimental and theoretical formulas for the thermophoretic velocity U of a macroscopic (i.e., non-Brownian) non-heat-conducting particle moving under the influence of a uniform temperature gradient through an otherwise quiescent single-component rarefied gas continuum at small Knudsen numbers. Coupled with the size independence of the particle's thermophoretic velocity, the empirically observed equality, U=UD, leads naturally to the hypothesis that these two velocities, the former real and the latter virtual, are, in fact, simply manifestations of the same underlying molecular phenomenon, namely the gas's Brownian movement, albeit biased by the temperature gradient. This purely hydrodynamic continuum-mechanical equality is confirmed by theoretical calculations effected at the kinetic-molecular level on the basis of an existing solution of the Boltzmann equation for a quasi-Lorentzian gas, modulo small uncertainties pertaining to the choice of collision model. Explicitly, this asymptotically valid molecular model allows the virtual drift velocity UD of the light gas and the thermophoretic velocity U of the massive, effectively non-Brownian, particle, now regarded as the tracer particle
Benchmarking sheath subgrid boundary conditions for macroscopic-scale simulations
NASA Astrophysics Data System (ADS)
Jenkins, T. G.; Smithe, D. N.
2015-02-01
The formation of sheaths near metallic or dielectric-coated wall materials in contact with a plasma is ubiquitous, often giving rise to physical phenomena (sputtering, secondary electron emission, etc) which influence plasma properties and dynamics both near and far from the material interface. In this paper, we use first-principles PIC simulations of such interfaces to formulate a subgrid sheath boundary condition which encapsulates fundamental aspects of the sheath behavior at the interface. Such a boundary condition, based on the capacitive behavior of the sheath, is shown to be useful in fluid simulations wherein sheath scale lengths are substantially smaller than scale lengths for other relevant physical processes (e.g. radiofrequency wavelengths), in that it enables kinetic processes associated with the presence of the sheath to be numerically modeled without explicit resolution of spatial and temporal sheath scales such as electron Debye length or plasma frequency.
Using explicit macroscopic feedback to determine efficacy of climate forcings
NASA Astrophysics Data System (ADS)
Kravitz, B.; MacMartin, D. G.
2013-12-01
Calculating efficacies of climate forcings has been a useful method of determining the importance of forcing agents relative to CO2. However, because the strength of internal feedbacks is dependent upon the climate state, efficacies are dependent upon the strengths of the applied forcings, and simulations designed to capture these efficacies have tradeoffs between simulation length and accurately capturing the steady state climate response. We propose an alternate method of determining a quantity similar to climate efficacy via adjusting the amount of forcing by feeding back the observed climate state. By balancing CO2 forcing with another climate forcing, many internal feedbacks are suppressed, which linearizes the climate response to the forcing and promotes rapid convergence of the simulation. We performed simulations in two fully coupled general circulation models of Earth's climate. Doubling the present day CO2 concentration requires a steady state solar reduction of approximately 2.5%; this answer can be obtained with a simulation of less than 30 years. With this method, the amount of solar reduction scales linearly with the logarithmic change in CO2 concentration. We explore similar calculations using other climate forcings. Because this method circumvents calculation of radiative forcing, intercomparison of values between different climate forcings is difficult and is a drawback of our method as compared to the original method of calculating efficacy. Feedback can be used to estimate the efficacy of solar reductions in models. The solar reduction that is required to maintain temperature in the presence of an instantaneous change in atmospheric CO2 concentrations is computed using feedback. The left-hand panel illustrates both the solar forcing as a function of time for offsetting 2×CO2, and the efficacy estimated as the mean solar reduction after the initial transient; extremely rapid convergence is obtained. The right-hand panel illustrates the linearity
Keyes, Joseph T.; Haskett, Darren G.; Utzinger, Urs; Azhar, Mohamad
2012-01-01
Murine models of disease are a powerful tool for researchers to gain insight into disease formation, progression, and therapies. The biomechanical indicators of diseased tissue provide a unique insight into some of these murine models, since the biomechanical properties in scenarios such as aneurysm and Marfan syndrome can dictate tissue failure and mortality. Understanding the properties of the tissue on the macroscopic scale has been shown to be important, as one can then understand the tissue’s ability to withstand the high stresses seen in the cardiac pulsatile cycle. Alterations in the biomechanical response can foreshadow prospective mechanical failure of the tissue. These alterations are often seen on the microstructural level, and obtaining detailed information on such changes can offer a better understanding of the phenomena seen on the macroscopic level. Unfortunately, mouse models present problems due to the size and delicate features in the mechanical testing of such tissues. In addition, some smaller arteries in large-animal studies (e.g., coronary and cerebral arteries) can present the same issues, and are sometimes unsuitable for planar biaxial testing. The purpose of this paper is to present a robust method for the investigation of the mechanical properties of small arteries and the classification of the microstructural orientation and degree of fiber alignment. This occurs through the cost-efficient modification of a planar biaxial tester that works in conjunction with a two-photon nonlinear microscope. This system provides a means to further investigate how microstructure and mechanical properties are modified in diseased transgenic animals where the tissue is in small tube form. Several other hard-to-test tubular specimens such as cerebral aneurysm arteries and atherosclerotic coronary arteries can also be tested using the described modular device. PMID:21823753
Fe(II) uptake on natural montmorillonites. I. Macroscopic and spectroscopic characterization.
Soltermann, Daniela; Marques Fernandes, Maria; Baeyens, Bart; Dähn, Rainer; Joshi, Prachi A; Scheinost, Andreas C; Gorski, Christopher A
2014-01-01
Iron is an important redox-active element that is ubiquitous in both engineered and natural environments. In this study, the retention mechanism of Fe(II) on clay minerals was investigated using macroscopic sorption experiments combined with Mössbauer and extended X-ray absorption fine structure (EXAFS) spectroscopy. Sorption edges and isotherms were measured under anoxic conditions on natural Fe-bearing montmorillonites (STx, SWy, and SWa) having different structural Fe contents ranging from 0.5 to 15.4 wt % and different initial Fe redox states. Batch experiments indicated that, in the case of low Fe-bearing (STx) and dithionite-reduced clays, the Fe(II) uptake follows the sorption behavior of other divalent transition metals, whereas Fe(II) sorption increased by up to 2 orders of magnitude on the unreduced, Fe(III)-rich montmorillonites (SWy and SWa). Mössbauer spectroscopy analysis revealed that nearly all the sorbed Fe(II) was oxidized to surface-bound Fe(III) and secondary Fe(III) precipitates were formed on the Fe(III)-rich montmorillonite, while sorbed Fe is predominantly present as Fe(II) on Fe-low and dithionite-reduced clays. The results provide compelling evidence that Fe(II) uptake characteristics on clay minerals are strongly correlated to the redox properties of the structural Fe(III). The improved understanding of the interfacial redox interactions between sorbed Fe(II) and clay minerals gained in this study is essential for future studies developing Fe(II) sorption models on natural montmorillonites.
NASA Astrophysics Data System (ADS)
Hennessy, Ricky; Koo, Chiwan; Ton, Phuc; Han, Arum; Righetti, Raffaella; Maitland, Kristen C.
2011-03-01
Ultrasound poroelastography can quantify structural and mechanical properties of tissues such as stiffness, compressibility, and fluid flow rate. This novel ultrasound technique is being explored to detect tissue changes associated with lymphatic disease. We have constructed a macroscopic fluorescence imaging system to validate ultrasonic fluid flow measurements and to provide high resolution imaging of microfluidic phantoms. The optical imaging system is composed of a white light source, excitation and emission filters, and a camera with a zoom lens. The field of view can be adjusted from 100 mm x 75 mm to 10 mm x 7.5 mm. The microfluidic device is made of polydimethylsiloxane (PDMS) and has 9 channels, each 40 μm deep with widths ranging from 30 μm to 200 μm. A syringe pump was used to propel water containing 15 μm diameter fluorescent microspheres through the microchannels, with flow rates ranging from 0.5 μl/min to 10 μl/min. Video was captured at a rate of 25 frames/sec. The velocity of the microspheres in the microchannels was calculated using an algorithm that tracked the movement of the fluorescent microspheres. The imaging system was able to measure particle velocities ranging from 0.2 mm/sec to 10 mm/sec. The range of flow velocities of interest in lymph vessels is between 1 mm/sec to 10 mm/sec; therefore our imaging system is sufficient to measure particle velocity in phantoms modeling lymphatic flow.
Shi, Xiaomeng; Ye, Zhirui; Shiwakoti, Nirajan; Tang, Dounan; Wang, Chao; Wang, Wei
2016-10-01
A recent crowd stampede during a New Year's Eve celebration in Shanghai, China resulted in 36 fatalities and over 49 serious injuries. Many of such tragic crowd accidents around the world resulted from complex multi-direction crowd movement such as merging behavior. Although there are a few studies on merging crowd behavior, none of them have conducted a systematic analysis considering the impact of both merging angle and flow direction towards the safety of pedestrian crowd movement. In this study, a series of controlled laboratory experiments were conducted to examine the safety constraints of merging pedestrian crowd movements considering merging angle (60°, 90° and 180°) and flow direction under slow running and blocked vision condition. Then, macroscopic and microscopic properties of crowd dynamics are obtained and visualized through the analysis of pedestrian crowd trajectory data derived from video footage. It was found that merging angle had a significant influence on the fluctuations of pedestrian flows, which is important in a critical situation such as emergency evacuation. As the merging angle increased, mean velocity and mean flow at the measuring region in the exit corridors decreased, while mean density increased. A similar trend was observed for the number of weaving and overtaking conflicts, which resulted in the increase of mean headway. Further, flow direction had a significant impact on the outflow of the individuals while blocked vision had an influence on pedestrian crowd interactions and merging process. Finally, this paper discusses safety assessments on crowd merging behaviors along with some recommendations for future research. Findings from this study can assist in the development and validation of pedestrian crowd simulation models as well as organization and control of crowd events.
Melittin-induced changes of the macroscopic structure of phosphatidylethanolamines
Batenburg, A.M.; van Esch, J.H.; Kruijff, B.
1988-04-05
The binding of melittin to phosphatidylethanolamine model systems and its influence on the supramolecular organization of the lipid were investigated with binding assays, differential scanning calorimetry, /sup 31/P NMR, freeze-fracture electron microscopy, and small-angle X-ray scattering. The results are compared with binding to an analogous phosphatidylcholine and structural consequences thereof. Melittin binds with similar affinity to both lipid types in the liquid-crystalline state; at gel-phase temperatures, in contrast, interaction with phosphatidylethanolmaine is much weaker and does not lead to the bilayer fragmentation observed for phosphatidylcholines. With regard to phosphatidylethanolamine polymorphism, it is shown that melittin acts as an inhibitor of H/sub II/-phase formation and as a stabilizer of the bilayer organization. It is demonstrated that the remarkable variety of effects of melittin on the polymorphism of different membrane phospholipids can be understood in a relatively simple concept, taking into account the relative position and the shape of the interacting components
Signatures of a macroscopic switching transition for a dynamic microtubule
Aparna, J. S.; Padinhateeri, Ranjith; Das, Dibyendu
2017-01-01
Characterising complex kinetics of non-equilibrium self-assembly of bio-filaments is of general interest. Dynamic instability in microtubules, consisting of successive catastrophes and rescues, is observed to occur as a result of the non-equilibrium conversion of GTP-tubulin to GDP-tubulin. We study this phenomenon using a model for microtubule kinetics with GTP/GDP state-dependent polymerisation, depolymerisation and hydrolysis of subunits. Our results reveal a sharp switch-like transition in the mean velocity of the filaments, from a growth phase to a shrinkage phase, with an associated co-existence of the two phases. This transition is reminiscent of the discontinuous phase transition across the liquid-gas boundary. We probe the extent of discontinuity in the transition quantitatively using characteristic signatures such as bimodality in velocity distribution, variance and Binder cumulant, and also hysteresis behaviour of the system. We further investigate ageing behaviour in catastrophes of the filament, and find that the multi-step nature of catastrophes is intensified in the vicinity of the switching transition. This assumes importance in the context of Microtubule Associated Proteins which have the potential of altering kinetic parameter values. PMID:28374844
Local and macroscopic electrostatic interactions in single α-helices
Baker, Emily G.; Bartlett, Gail J.; Crump, Matthew P.; Sessions, Richard B.; Linden, Noah; Faul, Charl F. J.; Woolfson, Derek N.
2015-01-01
The non-covalent forces that stabilise protein structures are not fully understood. One way to address this is to study equilibria between unfolded states and α-helices in peptides. For these, electrostatic forces are believed to contribute, including interactions between: side chains; the backbone and side chains; and side chains and the helix macrodipole. Here we probe these experimentally using designed peptides. We find that both terminal backbone-side chain and certain side chain-side chain interactions (i.e., local effects between proximal charges, or interatomic contacts) contribute much more to helix stability than side chain-helix macrodipole electrostatics, which are believed to operate at larger distances. This has implications for current descriptions of helix stability, understanding protein folding, and the refinement of force fields for biomolecular modelling and simulations. In addition, it sheds light on the stability of rod-like structures formed by single α-helices that are common in natural proteins including non-muscle myosins. PMID:25664692
Macroscopic wettability based on an interfacial jump condition
NASA Astrophysics Data System (ADS)
Yonemoto, Yukihiro; Kunugi, Tomoaki
2010-05-01
Young’s equation, describing an interfacial equilibrium condition of a liquid droplet on a smooth solid surface, raises issues concerning the existence of a sine term which has not yet been resolved theoretically and continues to be discussed to the present day. From a thermodynamics viewpoint, the equilibrium condition arises by minimizing the total free energy of the system while intensive parameters are kept constant. In the derivation, variations in the virtual work in both horizontal and vertical directions of the droplet on the smooth solid are considered. From a hydrodynamics viewpoint, there is a momentum jump condition at the gas-liquid interface that is derived based on a mechanical balance. Using standard mathematical procedures such as Stokes’ theorem and differential geometry, a test volume is considered across the interface between two continuous phases from which the jump condition is derived. In the present paper, Young’s equation is revisited from the point of view of the momentum jump condition at the two-phase interface and a modified Young’s equation is derived. The analytical solution derived from the modified Young’s equation is then used to compare theory with experimental data. The line tension and contact angle for a lens droplet are also discussed on the basis of this model.
Morphogenesis as a macroscopic self-organizing process.
Beloussov, Lev V
2012-09-01
We start from reviewing different epistemological constructions used for explaining morphogenesis. Among them, we explore the explanatory power of a law-centered approach which includes top-down causation and the basic concepts of a self-organization theory. Within such a framework, we discuss the morphomechanical models based upon the presumption of feedbacks between mechanical stresses imposed onto a given embryo part from outside and those generated within the latter as a kind of active response. A number of elementary morphogenetic events demonstrating that these feedbacks are directed towards hyper-restoration (restoration with an overshoot) of the initial state of mechanical stresses are described. Moreover, we show that these reactions are bound together into the larger scale feedbacks. That permits to suggest a reconstruction of morphogenetic successions in early Metazoan development concentrated around two main archetypes distinguished by the blastopores geometry. The perspectives of applying the same approach to cell differentiation are outlined. By discussing the problem of positional information we suggest that the developmental pathway of a given embryo part depends upon its preceded deformations and the corresponding mechanical stresses rather than upon its static position at any moment of development.