1,893 research outputs found
Competitive nucleation in reversible Probabilistic Cellular Automata
The problem of competitive nucleation in the framework of Probabilistic
Cellular Automata is studied from the dynamical point of view. The dependence
of the metastability scenario on the self--interaction is discussed. An
intermediate metastable phase, made of two flip--flopping chessboard
configurations, shows up depending on the ratio between the magnetic field and
the self--interaction. A behavior similar to the one of the stochastic
Blume--Capel model with Glauber dynamics is found
Monte Carlo study of gating and selection in potassium channels
The study of selection and gating in potassium channels is a very important
issue in modern biology. Indeed such structures are known in all types of cells
in all organisms where they play many important functional roles. The mechanism
of gating and selection of ionic species is not clearly understood. In this
paper we study a model in which gating is obtained via an affinity-switching
selectivity filter. We discuss the dependence of selectivity and efficiency on
the cytosolic ionic concentration and on the typical pore open state duration.
We demonstrate that a simple modification of the way in which the selectivity
filter is modeled yields larger channel efficiency
Phase ordering in chaotic map lattices with conserved dynamics
Dynamical scaling in a two-dimensional lattice model of chaotic maps, in
contact with a thermal bath, is numerically studied. The model here proposed is
equivalent to a conserved Ising model with coupligs which fluctuate over the
same time scale as spin moves. When couplings fluctuations and thermal
fluctuations are both important, this model does not belong to the class of
universality of a Langevin equation known as model B; the scaling exponents are
continuously varying with the temperature and depend on the map used. The
universal behavior of model B is recovered when thermal fluctuations are
dominant.Comment: 6 pages, 4 figures. Revised version accepted for publication on
Physical Review E as a Rapid Communicatio
Phase transitions for the cavity approach to the clique problem on random graphs
We give a rigorous proof of two phase transitions for a disordered system
designed to find large cliques inside Erdos random graphs. Such a system is
associated with a conservative probabilistic cellular automaton inspired by the
cavity method originally introduced in spin glass theory.Comment: 36 pages, 4 figure
Topology-Induced Critical Current Enhancement in Josephson Networks
We investigate the properties of Josephson junction networks with
inhomogeneous architecture. The networks are shaped as "quare comb" planar
lattices on which Josephson junctions link superconducting islands arranged in
the plane to generate the pertinent topology. Compared to the behavior of
reference linear arrays, the temperature dependencies of the Josephson currents
of the branches of the network exhibit relevant differences. The observed
phenomena evidence new and surprising behavior of superconducting Josephson
arrays as well as remarkable similarities with bosonic junction arrays.Comment: improved figures (added magnetic pattern and single junction
switching) some changes in the text and in the titl
How the design of Complete Streets affects mode choice: Understanding the behavioral responses to the level of traffic stress
Following a federal policy statement in 2010 supporting bicycle and pedestrian accommodation in federal-aid transportation projects, many cities across the US have implemented Complete Streets principles and invested in developing better-planned infrastructure that can be safely accessed by a diversity of modes of transportation by all types of users, in a mix of land uses. However, most of the travel demand forecasting models and planning tools used in practice are not sensitive to changes in demand for non-motorized modes such as walking and cycling in response to road infrastructure improvements. Hence, there is a need for models and tools that are capable of evaluating impacts of infrastructure changes that include Complete Streets implementations on the travel behavior, and estimate shifts in mode choices from motorized to non-motorized modes. This paper proposes a specific data collection plan, a multi-modal choice model, and strategies to update traditional trip-based transportation models to forecast rates of non-motorized trips for evaluating Complete Streets plans at a higher level. Concretely, we estimate elasticities to Level of Traffic Stress, which defines the comfort or discomfort experienced by walkers and bikers, segmented by income levels and trip purposes. We then use them to compute the new non-motorized mode shares that would be achieved by improving CS attributes leading to lower levels of traffic stress. The proposed modeling framework has been successfully applied to the Maryland Statewide Transportation Model, producing reliable non-motorized trip rates, and can be extended to other methodological frameworks used by public agenciesThis research was sponsored by the Maryland Department of Transportation State Highway Administration (Project No: MD-21-
SHA/UM/5-25, Erdogan et al., 2021), and the Urban Mobility & Equity Center (UMEC), based at Morgan State Universit
Effect of Chemically Induced Hypoxia on Osteogenic and Angiogenic Differentiation of Bone Marrow Mesenchymal Stem Cells and Human Umbilical Vein Endothelial Cells in Direct Coculture
Bone is an active tissue where bone mineralization and resorption occur simultaneously. In the case of fracture, there are numerous factors required to facilitate bone healing including precursor cells and blood vessels. To evaluate the interaction between bone marrow-derived mesenchymal stem cells (BMSC)-the precursor cells able to differentiate into bone-forming cells and human umbilical vein endothelial cells (HUVEC)-a cell source widely used for the study of blood vessels. We performed direct coculture of BMSC and HUVEC in normoxia and chemically induced hypoxia using Cobalt(II) chloride and Dimethyloxaloylglycine and in the condition where oxygen level was maintained at 1% as well. Cell proliferation was analyzed by crystal violet staining. Osteogenesis was examined by Alizarin Red and Collagen type I staining. Expression of angiogenic factor-vascular endothelial growth factor (VEGF) and endothelial marker-von Willebrand factor (VWF) were demonstrated by immunohistochemistry and enzyme-linked immunosorbent assay. The quantitative polymerase chain reaction was also used to evaluate gene expression. The results showed that coculture in normoxia could retain both osteogenic differentiation and endothelial markers while hypoxic condition limits cell proliferation and osteogenesis but favors the angiogenic function even after 1 of day treatment
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