Effect of cooperative merging on the synchronous flow phase of traffic

Cooperation in merging is introduced by adding interactions between pairs of vehicles in opposite lanes. Simulations with an improved version of the modified optimal velocity model are done for two lanes merging into a single lane. For ~30 seconds prior to reaching the merge region, vehicles in both lanes adjust their headways to create safe distances in front of and behind the merging vehicle. Cooperation prevents the transition from free flow to synchronous flow that occurs for normal merging, provided the merge region is sufficiently large and the total incoming flow does not exceed the maximum possible single-lane flow. No long-range vehicle-to-vehicle communication is required for the type of cooperation considered.Comment: 23 pages, 9 figures, accepted by Physica

Tree Growth as Affected by Cover Crops

A seven-row shelterbelt approximately one-half mile in length was started in the spring of 1938. The rows of the belt were planted north and south for about three-fourths of their length, and east and -west for the remainder. The outer row on the west and north was Caragana followed by Russian olive, green ash, American elm, green ash, American elm and Ponderosa pine. The rows were all spaced six feet apart, and the Caragana about three foot part in the row

One-Electron and Phonon-Assisted Tunneling in N-Ge Schottky Barriers

Coordinated Science Laboratory was formerly known as Control Systems LaboratoryJoint Services Electronics Program / DAAB-07-67-C-0199National Aeronautics and Space Administration / NsG 228-62U.S. Army Research Office (Durham) / DA-31-124-ARO(D)-11

Homogenization of weakly coupled systems of Hamilton--Jacobi equations with fast switching rates

We consider homogenization for weakly coupled systems of Hamilton--Jacobi equations with fast switching rates. The fast switching rate terms force the solutions converge to the same limit, which is a solution of the effective equation. We discover the appearance of the initial layers, which appear naturally when we consider the systems with different initial data and analyze them rigorously. In particular, we obtain matched asymptotic solutions of the systems and rate of convergence. We also investigate properties of the effective Hamiltonian of weakly coupled systems and show some examples which do not appear in the context of single equations.Comment: final version, to appear in Arch. Ration. Mech. Ana

Reviewing the International Year of Deserts and Desertification 2006: What contribution towards combating global desertification and implementing the united nations convention to combat desertification?

During the United Nations General Assembly's 58th Ordinary Session in 2003, a decision was adopted declaring 2006 the International Year of Deserts and Desertification (IYDD). This paper critically reviews this International Year. It draws on the key outputs from IYDD events from across the globe to highlight the challenges and ways forward in both combating desertification and implementing the United Nations Convention to Combat Desertification (UNCCD). The paper considers what the IYDD outputs mean for the current and historical controversies surrounding the desertification issue and presents an overall evaluation of the successes of IYDD for the different stakeholder groups within the desertification regime. It is concluded that while the International Year can be considered to have met the United Nations's four objectives: to address the long-term oriented implementation of the UNCCD; raise awareness of the implications of desertification; facilitate networking with all stakeholders; and disseminate information relating to the UNCCD, the real challenge lies in moving the IYDD outcomes away from the conferences, meetings and networks that contributed to their generation, towards a more concrete, tangible effort to conserve deserts and effectively monitor and control desertification and land degradation on the ground

Network Landscape from a Brownian Particle's Perspective

Given a complex biological or social network, how many clusters should it be decomposed into? We define the distance $d_{i,j}$ from node $i$ to node $j$ as the average number of steps a Brownian particle takes to reach $j$ from $i$. Node $j$ is a global attractor of $i$ if $d_{i,j}\leq d_{i,k}$ for any $k$ of the graph; it is a local attractor of $i$, if $j\in E_i$ (the set of nearest-neighbors of $i$) and $d_{i,j}\leq d_{i,l}$ for any $l\in E_i$. Based on the intuition that each node should have a high probability to be in the same community as its global (local) attractor on the global (local) scale, we present a simple method to uncover a network's community structure. This method is applied to several real networks and some discussion on its possible extensions is made.Comment: 5 pages, 4 color-figures. REVTeX 4 format. To appear in PR

Ground state of a polydisperse electrorheological solid: Beyond the dipole approximation

The ground state of an electrorheological (ER) fluid has been studied based on our recently proposed dipole-induced dipole (DID) model. We obtained an analytic expression of the interaction between chains of particles which are of the same or different dielectric constants. The effects of dielectric constants on the structure formation in monodisperse and polydisperse electrorheological fluids are studied in a wide range of dielectric contrasts between the particles and the base fluid. Our results showed that the established body-centered tetragonal ground state in monodisperse ER fluids may become unstable due to a polydispersity in the particle dielectric constants. While our results agree with that of the fully multipole theory, the DID model is much simpler, which offers a basis for computer simulations in polydisperse ER fluids.Comment: Accepted for publications by Phys. Rev.

Infrared optical properties of the spin-1/2 quantum magnet TiOClTiOCl

We report results on the electrodynamic response of $TiOCl$, a low-dimensional spin-1/2 quantum magnet that shows a spin gap formation for T$<T_{c1}$= 67 $K$. The Fano-like shape of a few selected infrared active phonons suggests an interaction between lattice vibrations and a continuum of low frequency (spin) excitations. The temperature dependence of the phonon mode parameters extends over a broad temperature range well above $T_{c1}$, indicating the presence of an extended fluctuation regime. In the temperature interval between 200 $K$ and $T_{c1}$ there is a progressive dimensionality crossover (from two to one), as well as a spectral weight shift from low towards high frequencies. This allows us to identify a characteristic energy scale of about 430 $K$, ascribed to a pseudo spin-gap

Upper estimate of martingale dimension for self-similar fractals

We study upper estimates of the martingale dimension $d_m$ of diffusion processes associated with strong local Dirichlet forms. By applying a general strategy to self-similar Dirichlet forms on self-similar fractals, we prove that $d_m=1$ for natural diffusions on post-critically finite self-similar sets and that $d_m$ is dominated by the spectral dimension for the Brownian motion on Sierpinski carpets.Comment: 49 pages, 7 figures; minor revision with adding a referenc

Adjustment to colostomy: stoma acceptance, stoma care self-efficacy and interpersonal relationships

‘The definitive version is available at www.blackwell-synergy.com.’ Copyright Blackwell Publishing. DOI: 10.1111/j.1365-2648.2007.04446.xThis paper is a report of a study to examine adjustment and its relationship with stoma acceptance and social interaction, and the link between stoma care self-efficacy and adjustment in the presence of acceptance and social interactions.Peer reviewe