{"title":"Finite-amplitude double-component convection due to different boundary conditions for two compensating horizontal gradients","authors":"Tsitverblit","doi":"10.1103/physreve.62.r7591","DOIUrl":"https://doi.org/10.1103/physreve.62.r7591","url":null,"abstract":"<p><p>Finite-amplitude convective steady flows that do not bifurcate from the respective conduction state are discovered. They arise as the compensating horizontal gradients of two density-affecting components with equal diffusivities but different boundary conditions are applied to the Boussinesq fluid at rest with and without stable vertical stratification. These flows emanate from convection in a laterally heated stably stratified slot. Their relevance to convective states in a horizontal slot with two vertical gradients, emphasizing universality of the underlying type of convection, is discussed.</p>","PeriodicalId":20079,"journal":{"name":"Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics","volume":"62 6 Pt A","pages":"R7591-4"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1103/physreve.62.r7591","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21959006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Optimal pruning in neural networks.","authors":"D M Barbato, O Kinouchi","doi":"10.1103/physreve.62.8387","DOIUrl":"https://doi.org/10.1103/physreve.62.8387","url":null,"abstract":"<p><p>We study pruning strategies in simple perceptrons subjected to supervised learning. Our analytical results, obtained through the statistical mechanics approach to learning theory, are independent of the learning algorithm used in the training process. We calculate the post-training distribution P(J) of synaptic weights, which depends only on the overlap rho(0) achieved by the learning algorithm before pruning and the fraction kappa of relevant weights in the teacher network. From this distribution, we calculate the optimal pruning strategy for deleting small weights. The optimal pruning threshold grows from zero as straight theta(opt)(rho(0), kappa) approximately [rho(0)-rho(c)(kappa)](1/2) above some critical value rho(c)(kappa). Thus, the elimination of weak synapses enhances the network performance only after a critical learning period. Possible implications for biological pruning phenomena are discussed.</p>","PeriodicalId":20079,"journal":{"name":"Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics","volume":"62 6 Pt B","pages":"8387-94"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1103/physreve.62.8387","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21959301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Equation of state of fully ionized electron-ion plasmas. II. Extension To relativistic densities and to the solid phase","authors":"Potekhin, Chabrier","doi":"10.1103/physreve.62.8554","DOIUrl":"https://doi.org/10.1103/physreve.62.8554","url":null,"abstract":"<p><p>The analytic equation of state of nonideal Coulomb plasmas consisting of pointlike ions immersed in a polarizable electron background [G. Chabrier and A. Y. Potekhin, Phys. Rev. E 58, 4941 (1998)] is improved, and its applicability range is considerably extended. First, the fit of the electron screening contribution in the free energy of the Coulomb liquid is refined at high densities where the electrons are relativistic. Second, we calculate the screening contribution for the Coulomb solid (bcc and fcc) and derive an analytic fitting expression. Third, we propose a simple approximation to the internal and free energy of the liquid one-component plasma of ions, accurate within the numerical errors of the most recent Monte Carlo simulations. We obtain an updated value of the coupling parameter at the solid-liquid phase transition for the one-component plasma: Gamma(m)=175.0+/-0.4(1sigma).</p>","PeriodicalId":20079,"journal":{"name":"Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics","volume":"62 6 Pt B","pages":"8554-63"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1103/physreve.62.8554","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21959793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Equilibrium shapes and faceting for ionic crystals of body-centered-cubic type","authors":"Carlon, van Beijeren H","doi":"10.1103/physreve.62.7646","DOIUrl":"https://doi.org/10.1103/physreve.62.7646","url":null,"abstract":"<p><p>A mean-field theory is developed for a calculation of the surface free energy of the staggered body-centered solid-on-solid (or six vertex) model as function of the surface orientation and temperature. The model approximately describes surfaces of crystals with nearest neighbor attractions, and next nearest neighbor repulsions. The mean-field free energy is calculated by expressing the model in terms of interacting directed walks on a lattice. The resulting equilibrium shape is very rich with facet boundaries and boundaries between reconstructed and unreconstructed regions, which can be either sharp (first order) or smooth (continuous). In addition, there are tricritical points where a smooth boundary changes into a sharp one, and triple points where three sharp boundaries meet. Finally our numerical results strongly suggest the existence of conical points, at which tangent planes of a finite range of orientations all intersect each other. The thermal evolution of the equilibrium shape in this model shows a strong similarity to that seen experimentally for ionic crystals.</p>","PeriodicalId":20079,"journal":{"name":"Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics","volume":"62 6 Pt A","pages":"7646-57"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1103/physreve.62.7646","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21958994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effect of long range order on sheared liquid crystalline materials: flow regimes, transitions, and rheological phase diagrams","authors":"Tsuji, Rey","doi":"10.1103/physreve.62.8141","DOIUrl":"https://doi.org/10.1103/physreve.62.8141","url":null,"abstract":"<p><p>A generalized theory that includes short-range elasticity, long-range elasticity, and flow effects is used to simulate and characterize the shear flow of liquid crystalline materials as a function of the Deborah (De) and Ericksen (Er) numbers in the presence of fixed planar director boundary conditions; the results are also interpreted as a function of the ratio R between short-range and long-range elasticity. The results are effectively summarized into rheological phase diagrams spanned by De and Er, and also by R and Er, where the stability region of four distinct flow regimes are indicated. The four regimes for planar (two-dimensional orientation) shear flow are (1) the elastic-driven steady state, (2) the composite tumbling-wagging periodic state, (3) the wagging periodic state, and (4) the viscous-driven steady state. The coexistence of the four regimes at a quacritical point is shown to be due to the emergence of a defect structure. The origin, the significant steady and dynamical features, and the transitions between these regimes are thoroughly characterized and analyzed. Quantitative and qualitative comparisons between the present complete model predictions and those obtained from the classical theories of nematodynamics (Leslie-Ericksen and Doi theories) are presented and the main physical mechanisms that drive the observed deviations between the predictions of these models are identified. The presented results fill the previously existing gap between the classical Leslie-Ericksen theory and the Doi theory, and present a unified description of nematodynamics.</p>","PeriodicalId":20079,"journal":{"name":"Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics","volume":"62 6 Pt A","pages":"8141-51"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1103/physreve.62.8141","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21958997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Replica-exchange algorithm and results for the three-dimensional random field ising model","authors":"Machta, Newman, Chayes","doi":"10.1103/physreve.62.8782","DOIUrl":"https://doi.org/10.1103/physreve.62.8782","url":null,"abstract":"<p><p>The random field Ising model with Gaussian disorder is studied using a different Monte Carlo algorithm. The algorithm combines the advantages of the replica-exchange method and the two-replica cluster method and is much more efficient than the Metropolis algorithm for some disorder realizations. Three-dimensional systems of size 24(3) are studied. Each realization of disorder is simulated at a value of temperature and uniform field that is adjusted to the phase-transition region for that disorder realization. Energy and magnetization distributions show large variations from one realization of disorder to another. For some realizations of disorder there are three well separated peaks in the magnetization distribution and two well separated peaks in the energy distribution suggesting a first-order transition.</p>","PeriodicalId":20079,"journal":{"name":"Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics","volume":"62 6 Pt B","pages":"8782-9"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1103/physreve.62.8782","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21959014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Parity-violating effects in asymmetric chemical reactions: A theoretical study on the CHFClBr molecule","authors":"Soncini, Ligabue, Lazzeretti, Zanasi","doi":"10.1103/physreve.62.8395","DOIUrl":"https://doi.org/10.1103/physreve.62.8395","url":null,"abstract":"<p><p>A coupled Hartree-Fock procedure has been employed to estimate the parity-violating energy contribution due to electroweak interaction in the vicinity of the transition point of a chemical reaction path starting from achiral reagents and producing the chiral CHFClBr molecule. The calculations demonstrate that (i) the S enantiomer is a reaction product more stable than its mirror image by approximately 1x10(-17) hartree; (ii) in the transition state of the reaction, the chiral activated complex evolving toward the S-CHFClBr species is more stable, by approximately 2.3x10(-17) hartree, than the enantiomeric activated complex that would yield the R-CHFClBr species. These results suggest that kinetic effects at work during chemical syntheses of chiral molecules might be more significant than the different thermodynamical stability of the two mirror-image reaction products in determining the final configuration and to explain homochirality.</p>","PeriodicalId":20079,"journal":{"name":"Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics","volume":"62 6 Pt B","pages":"8395-9"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1103/physreve.62.8395","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21959302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Interaction of local anesthetics with phospholipids in Langmuir monolayers.","authors":"S Amador Kane, S D Floyd","doi":"10.1103/physreve.62.8400","DOIUrl":"https://doi.org/10.1103/physreve.62.8400","url":null,"abstract":"<p><p>We have used epifluorescence microscopy to study the interactions of two local anesthetics of the \"caine\" family (tetracaine and dibucaine), with Langmuir monolayers of the phospholipid dipalmitoylphosphatidylcholine (DPPC). These results show that incorporation of either dibucaine or tetracaine causes significant changes in the domain shapes of the liquid condensed phase in monolayers. In particular, at low pH, where the charged cationic form of the local anesthetics predominates, local anesthetic: DPPC monolayers formed significantly less compact liquid condensed domains with highly ramified shapes, compared to DPPC-only controls. For high pH values at which both local anesthetics are electrically neutral, the liquid condensed domains in mixed monolayers resembled that of DPPC-only controls, indicating that these effects have their origins in electrostatic interactions between the local anesthetics and the phospholipid headgroups. Epifluorescence images obtained using the intrinsic fluorescence of dibucaine indicated that dibucaine partitions into both the liquid condensed and liquid expanded phases.</p>","PeriodicalId":20079,"journal":{"name":"Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics","volume":"62 6 Pt B","pages":"8400-8"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1103/physreve.62.8400","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21959303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Spatiotemporal pattern formation in neural systems with heterogeneous connection topologies.","authors":"V K Jirsa, J A Kelso","doi":"10.1103/physreve.62.8462","DOIUrl":"https://doi.org/10.1103/physreve.62.8462","url":null,"abstract":"<p><p>Biological systems like the human cortex show homogeneous connectivity, with additional strongly heterogeneous projections from one area to another. Here we report how such a dynamic system performs a macroscopically coherent pattern formation. The connection topology is used systematically as a control parameter to guide the neural system through a series of phase transitions. We discuss the example of a two-point connection, and its destabilization mechanism.</p>","PeriodicalId":20079,"journal":{"name":"Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics","volume":"62 6 Pt B","pages":"8462-5"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1103/physreve.62.8462","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21959786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Pattern formation in a vibrated granular layer: the pattern selection issue","authors":"Clement, Labous","doi":"10.1103/physreve.62.8314","DOIUrl":"https://doi.org/10.1103/physreve.62.8314","url":null,"abstract":"<p><p>We present a numerical study of a surface instability occurring in a bidimensional vibrated granular layer. The driving mechanism for the formation of stationary waves is closely followed. Two regimes of wavelength selection are identified: a dispersive regime where the wavelength decreases with increasing frequency and a saturation regime where the value of the wavelength is a constant depending on the number of grains in the vertical direction. For the dispersive regime an empirical relation is proposed, based on dimensional arguments involving transport properties in the layer. A comparison is made with existing experimental results in two and three dimensions. For the saturation regime, a connection is established between the pattern formation and an intrinsic instability occurring spontaneously in dissipative gases. The observed dependence on the layer height is linked to a detailed dissipation mechanism for the collisions between grains.</p>","PeriodicalId":20079,"journal":{"name":"Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics","volume":"62 6 Pt B","pages":"8314-23"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1103/physreve.62.8314","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21959957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}