Extremal Segments in Random Sequences

We investigate the probability for the largest segment in with total displacement $Q$ in an $N$-step random walk to have length $L$. Using analytical, exact enumeration, and Monte Carlo methods, we reveal the complex structure of the probability distribution in the large $N$ limit. In particular, the size of the longest loop has a distribution with a square-root singularity at $\ell\equiv L/N=1$, an essential singularity at $\ell=0$, and a discontinuous derivative at $\ell=1/2$.Comment: 3 pages, REVTEX 3.0, with multicol.sty, epsf.sty and EPS figures appended via uufiles. (Email in case of trouble.) CHANGES: Missing figure added to figures.uu MIT-CMT-KE-94-

Cylindrical Ising Nanowire in an Oscillating Magnetic Field and Dynamic Compensation Temperature

The magnetic properties of a nonequilibrium spin-1/2 cylindrical Ising nanowire system with core/shell in an oscillating magnetic field are studied by using a mean-field approach based on the Glauber-type stochastic dynamics (DMFT). We employ the Glaubertype stochastic dynamics to construct set of the coupled mean-field dynamic equations. First, we study the temperature dependence of the dynamic order parameters to characterize the nature of the phase transitions and to obtain the dynamic phase transition points. Then, we investigate the temperature dependence of the total magnetization to find the dynamic compensation points as well as to determine the type of behavior. The phase diagrams in which contain the paramagnetic, ferromagnetic, antiferromagnetic, nonmagnetic, surface fundamental phases and tree mixed phases as well as reentrant behavior are presented in the reduced magnetic field amplitude and reduced temperature plane. According to values of Hamiltonian parameters, the compensation temperatures, or the N-, Q-, P-, R-, S-type behaviors in the Neel classification nomenclature exist in the system.Comment: 9 pages, 5 figure

Automatic Analyzer for Iterative Design

The Office of Naval Research Department Of The Navy Contract Nonr 1834 (03) Project NR-064-18

Effect of a plant-based hemostatic agent on microleakage of self-etching adhesives

Objective: This in vitro study evaluated the effect of Ankaferd Blood Stopper (ABS) contamination on the microleakage of one-step and two-step self-etching adhesives. Study design: Class V cavities were prepared at the cemento-enamel junction on both buccal and lingual surfaces of 60 freshly extracted human molars. Teeth were randomly assigned into three groups according to contamination material applied (Group I, no contamination; Group II, blood contamination; Group III, ABS contamination). In contaminated groups, one drop of blood and ABS solution was applied directly to the dentin surface and air-dried. Each group was further divided into two subgroups according to bonding agent used [Group A, Clearfil SE Bond (two-step self-etching adhesive); Group B, Adper Easy One (one-step self-etching adhesive)]. Adhesive materials were applied according to the manufacturers' recommendations. The specimens were restored using a universal microhybrid composite (Arabesk). After thermocycling (5000x, 5°C ' 55°C) and immersion in a 0.5% basic fuchsin, dye penetration was evaluated under a stereomicroscope. Statistical analysis was performed with Kruskal-Wallis and Mann-Whitney U tests at p < 0.05. Results: Significantly higher microleakage scores were observed when one-step self-etching adhesive was applied to blood- and ABS-contaminated dentin. However, when a two-step self etching adhesive was used, microleakage was observed only following blood contamination, not following ABS contamination. Conclusions: Although, blood contamination before adhesive application resulted in increased microleakage with both one-step and two-step self-etching adhesive systems, ABS contamination did not affect microleakage when a two-step self-ething adhesive system was used

Granular gravitational collapse and chute flow

Inelastic grains in a flow under gravitation tend to collapse into states in which the relative normal velocities of two neighboring grains is zero. If the time scale for this gravitational collapse is shorter than inverse strain rates in the flow, we propose that this collapse will lead to the formation of ``granular eddies", large scale condensed structures of particles moving coherently with one another. The scale of these eddies is determined by the gradient of the strain rate. Applying these concepts to chute flow of granular media, (gravitationally driven flow down inclined planes) we predict the existence of a bulk flow region whose rheology is determined only by flow density. This theory yields the experimental ``Pouliquen flow rule", correlating different chute flows; it also correctly accounts for the different flow regimes observed.Comment: LaTeX2e with epl class, 7 pages, 2 figures, submitted to Europhysics Letter