New lower bounds for asymmetric and unidirectional codes

New lower bounds on the sizes of asymmetric codes and unidirectional codes are presented. Various methods are used, three of them of special interest. The first is a partitioning method that is a modification of a method used to construct constant weight codes. The second is a combining codes method that is used to obtain a new code from a few others. The third method is shortening by weights that is applied on symmetric codes or on codes generated by the combining codes method. Tables for the sizes of codes of length n⩽23 are presented     

A method for constructing decodable de Bruijn sequences

We present two related methods of construction for de Bruijn (1946) sequences, both based on interleaving “smaller” de Bruijn sequences. Sequences obtained using these construction methods have the advantage that they can be “decoded” very efficiently, i.e., the position within the sequence of any particular “window” can be found very simply. Sequences with simple decoding algorithms are of considerable practical importance in position location applications     

Patterns of self-stabilization in database consistency maintenance

A substantial portion of the database programming efforts are invested in integrity constraints enforcement. Traditionally, both the constraint semantics and their enforcement were embedded inside application programs. In recent years several studies have dealt with specifying integrity constraints as separate entities (e.g. rules), and relating the database consistency requirements to these rules. In this paper we deal with the complementary issue of stabilizing the database when update exceptions occur. While a simplistic approach is to abort any transaction that inflicts consistency violations, this is not always the desired action. We take advantage of the empirical observation that most of the exception-handling policies follow a small number of behavior patterns. Unlike some previous approaches that base their repair solution on syntactic analysis of the constraints and performance issues, we base our approach on the application semantics as reflected in these behavioral patterns. We describe a model that uses high-level abstractions called stabilizer types denoting these behavior patterns for consistency restorations, whose exact semantics is case dependent. It follows the fault tolerance's self-stabilization approach. An inference mechanism translates these abstractions into executable active rules. This approach provides high-level language to the exception handling portion of the application and substantially reduces the required programming.     

Constructions of error-correcting DC-free block codes

Two DC-free codes are presented with distance 2d, b ⩾1 length 2n+2r(d-1) for d⩽3 and length 2n+2r(d-1)(2d -1) for d>3, where r is the least integer ⩾log₂ (2n+1). For the first code l=4, c=2, and the asymptotic rate of this code is 0.7925. For the second code l=6, c=3, and the asymptotic rate of this code is 0.8858. Asymptotically, these rates achieve the channel capacity. For small values of n these codes do not achieve the best rate. As an example of codes of short length with good rate, the author presents a (30, 10, 6, 4) DC-free block code with 2²¹ codewords. A construction is presented for which from a given code C ₁ of length n, even weight, and distance 4, the author obtains a (4n, l, c, 4) DC-free block code C₂, where l is 4, 5 or 6, and c is not greater than n+1 (but usually significantly smaller). The codes obtained by this method have good rates for small lengths. The encoding and decoding procedures for all the codes are discussed     

Quasi-perfect codes with small distance

The main purpose of this paper is to give bounds on the length of the shortest and longest binary quasi-perfect codes with a given Hamming distance, covering radius, and redundancy. We consider codes with Hamming distance 4 and 5 and covering radius 2 and 3, respectively. We discuss the blockwise direct sum (BDS) construction which has an important role in finding these bounds.     

Development of a plasma panel muon detector

A radiation detector technology based on plasma display panels (PDPs), the underlying engine of panel plasma television displays, is being investigated. Emerging from this well-established television technology is the Plasma Panel Sensor (PPS), a novel variant of the micro-pattern radiation detector. The PPS is fundamentally a fast, high-resolution detector comprised of an array of plasma discharge cells, operating in a hermetically sealed gas mixture. We report on the PPS development effort, including proof-of-principle results of laboratory signal observations.     

A preliminary coupled MT-GA model for the prediction of highway runoff quality

Pollutants accumulated on road pavement during dry periods are washed off the surface with runoff water during rainfall events, presenting a potentially hazardous non-point source of pollution. Estimation of pollutant loads in these runoff waters is required for developing mitigation and management strategies, yet the numerous factors involved and their complex interconnected influences make straightforward assessment impossible. Data-driven models (DDMs) have lately been used in water and environmental research and have shown very good prediction ability. The proposed methodology of a coupled MT-GA (model tree-genetic algorithm) model provides an effective, accurate and easily calibrated predictive model for EMC (event mean concentration) of highway runoff pollutants. The models were trained and verified using a comprehensive data set of runoff events monitored in various highways in California, USA. EMCs of Cr, Pb, Zn, TOC and TSS were modeled, using different combinations of explanatory variables. The models' prediction ability in terms of correlation between predicted and actual values of both training and verification data was mostly higher than previously reported values. Sensitivity analysis was performed to examine the relative significance of each explanatory variable and the models' response to changes in input values.     

Improved upper bounds on sizes of codes

Let A(n,d) denote the maximum possible number of codewords in a binary code of length n and minimum Hamming distance d. For large values of n, the best known upper bound, for fixed d, is the Johnson bound. We give a new upper bound which is at least as good as the Johnson bound for all values of n and d, and for each d there are infinitely many values of n for which the new bound is better than the Johnson bound. For small values of n and d, the best known method to obtain upper bounds on A(n,d) is linear programming. We give new inequalities for the linear programming and show that with these new inequalities some of the known bounds on A(n,d) for n⩽28 are improved     

The crossover of strain from school principals to teachers and vice versa.

The study investigated crossover of stress and strain in the workplace on a sample of 47 school principals and 183 teachers in Israeli elementary schools. The main goal of this study was to examine whether the crossover effect found among couples in the family also exists in the workplace. A 2nd aim of the study as to unravel the mechanisms that account for the crossover process. Using structural equation modeling, the authors found a significant crossover of job-induced tension but not of burnout from principals to teachers and vice versa. Being undermined by their principals elevated teachers' burnout and job-induced tension. This is the 1st study to demonstrate crossover of strain in the workplace and to discuss the implications of contagious job-induced tension in work environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Effect of Sera from Children with Obstructive Sleep Apnea Syndrome (OSAS) on Human Cardiomyocytes Differentiated from Human Embryonic Stem Cells

Obstructive sleep apnea syndrome (OSAS) patients suffer from cardiovascular morbidity, which is the leading cause of death in this disease. Based on our previous work with transformed cell lines and primary rat cardiomyocytes, we determined that upon incubation with sera from pediatric OSAS patients, the cell’s morphology changes, NF-κB pathway is activated, and their beating rate and viability decreases. These results suggest an important link between OSAS, systemic inflammatory signals and end-organ cardiovascular diseases. In this work, we confirmed and expanded these observations on a new in vitro system of beating human cardiomyocytes (CM) differentiated from human embryonic stem cells (hES). Our results show that incubation with pediatric OSAS sera, in contrast to sera from healthy children, induces over-expression of NF-κB p50 and p65 subunits, marked reduction in CMs beating rate, contraction amplitude and a strong reduction in intracellular calcium signal. The use of human CM cells derived from embryonic stem cells has not been previously reported in OSAS research. The results further support the hypothesis that NF-κB dependent inflammatory pathways play an important role in the evolution of cardiovascular morbidity in OSAS. This study uncovers a new model to investigate molecular and functional aspects of cardiovascular pathology in OSAS.