Deterministically driven random walks in a random environment on Z

We introduce the concept of a deterministic walk in a deterministic environment on a countable state space (DWDE). For the deterministic walk in a fixed environment we establish properties analogous to those found in Markov chain theory, but for systems that do not in general have the Markov property. In particular, we establish hypotheses ensuring that a DWDE on $\Z$ is either recurrent or transient. An immediate consequence of this result is that a symmetric DWDE on $\Z$ is recurrent. Moreover, in the transient case, we show that the probability that the DWDE diverges to $+ \infty$ is either 0 or 1. In certain cases we compute the direction of divergence in the transient case

Dynamic FOV visible light communications receiver for dense optical networks

This study explores how the field-of-view (FOV) of a visible light communications (VLCs) receiver can be manipulated to realise the best signal-to-noise ratio (SNR) while supporting device mobility and optimal access point (AP) selection. The authors propose a dynamic FOV receiver that changes its aperture according to receiver velocity, location, and device orientation. The D-FOV technique is evaluated through modelling, analysis, and experimentation in an indoor environment comprised of 15 VLC APs. The proposed approach is also realised as an algorithm that is studied through analysis and simulation. The results of the study indicate the efficacy of the approach including a 3X increase in predicted SNR over static FOV approaches based on measured received signal strength in the testbed. Additionally, the collected data reveal that D-FOV increases effectiveness in the presence of noise. Finally, the study describes the tradeoffs among the number of VLC sources, FOV, user device velocity, and SNR as a performance metric.Accepted manuscrip

Tensile film clamps and mounting block for the rheovibron and autovibron viscoelastometer

A set of film clamps and a mounting block for use in the determination of tensile modulus and damping properties of films in a manually operated or automated Rheovibron is diagrammed. These clamps and mounting block provide uniformity of sample gripping and alignment in the instrument. Operator dependence and data variability are greatly reduced

Reforming the U. S. health care system: where there's a will, there could be a way

The essay in the 2005 annual report summarizes the themes and consensus-based prescriptions for action that emerged from the Boston Fed's 50th economic conference, Wanting It All: The Challenge of Reforming the U.S. Health Care System, held in June 2005.Health care reform ; Medical care, Cost of

Condition monitoring of an advanced gas-cooled nuclear reactor core

A critical component of an advanced gas-cooled reactor station is the graphite core. As a station ages, the graphite bricks that comprise the core can distort and may eventually crack. Since the core cannot be replaced, the core integrity ultimately determines the station life. Monitoring these distortions is usually restricted to the routine outages, which occur every few years, as this is the only time that the reactor core can be accessed by external sensing equipment. This paper presents a monitoring module based on model-based techniques using measurements obtained during the refuelling process. A fault detection and isolation filter based on unknown input observer techniques is developed. The role of this filter is to estimate the friction force produced by the interaction between the wall of the fuel channel and the fuel assembly supporting brushes. This allows an estimate to be made of the shape of the graphite bricks that comprise the core and, therefore, to monitor any distortion on them

The preservation of quartz grain surface textures following vehicle fire and their use in forensic enquiry

During a terrorist trial, dispute arose as to whether the temperature produced in a car fire was sufficient to destroy quartz grain surface textures. A series of seven sequential experiments showed that the temperature for quartz surface texture modification/destruction and the production of vugs, vesicles and glassy precipitation ('snowdrifting') occurred at 1200 degrees C under normal atmospheric conditions. By adding a number of man-made and natural substances, it was found that only the presence of salts depressed this modification temperature (to 900 degrees C). Experiments to determine the temperature of fire in a car indicated that the maximum temperature produced under natural conditions (810 degrees C) was insufficient to affect the quartz grain Surface textures. These results confirm the use of surface texture analysis of quartz grains recovered from the remains of cars Subjected to fire and their use as a forensic indicator. (C) 2008 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved

High turnover in electro-oxidation of alcohols and ethers with a glassy carbon-supported phenanthroimidazole mediator.

Glassy carbon electrodes covalently modified with a phenanthroimidazole mediator promote electrochemical alcohol and ether oxidation: three orders of magnitude increase in TON, to ∼15 000 in each case, was observed compared with homogeneous mediated reactions. We propose the deactivation pathways in homogeneous solution are prevented by the immobilization: modified electrode reversibility is increased for a one-electron oxidation reaction. The modified electrodes were used to catalytically oxidize p-anisyl alcohol and 1-((benzyloxy)methyl)-4-methoxybenzene, selectively, to the corresponding benzaldehyde and benzyl ester, respectively

The Quality of School-Age Child Care in After-School Settings

This brief highlights current measures of quality in school-age settings as well as indicators linked to high-quality after-school programs and positive child outcomes