Extension of an entropy property for binary input memorylesssymmetric channels

The channel output entropy property introduced by A.D. Wyner and J. Ziv (ibid., vol.IT-19, p.769-762, Nov.1973) for a binary symmetric channel is extended to arbitrary memoryless symmetric channels with binary inputs and discrete or continuous outputs. This yields lower bounds on the achievable information rates of these channels under constrained binary inputs. Using the interpretation of entropy as a measure of order and randomness, the authors deduce that output sequences of memoryless symmetric channels induced by binary inputs are of a higher degree of randomness if the redundancy of the input binary sequence is spread in memory rather than in one-dimensional asymmetry. It is of interest to characterize the general class of schemes for which this interpretation holds     

Burnout and risk of cardiovascular disease: Evidence, possible causal paths, and promising research directions.

Burnout is characterized by emotional exhaustion, physical fatigue, and cognitive weariness, resulting from prolonged exposure to work-related stress. The authors review the accumulated evidence suggesting that burnout and the related concept of vital exhaustion are associated with increased risk of cardiovascular disease and cardiovascular-related events. The authors present evidence supporting several potential mechanisms linking burnout with ill health, including the metabolic syndrome, dysregulation of the hypothalamic-pituitary-adrenal axis along with sympathetic nervous system activation, sleep disturbances, systemic inflammation, impaired immunity functions, blood coagulation and fibrinolysis, and poor health behaviors. The association of burnout and vital exhaustion with these disease mediators suggests that their impact on health may be more extensive than currently indicated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Closed schedulers: a novel technique for analyzing asynchronous protocols

Summary Analyzing distributed protocols in various models often involves a careful analysis of the set ofadmissible runs, for which the protocols should behave correctly. In particular, the admissible runs assumed by at-resilient protocol are runs which are fair for all but at mostt processors. In this paper we defineclosed sets of runs, and suggest a technique to prove impossibility results fort-resilient protocols, by restricting the corresponding sets of admissible runs to smaller sets, which are closed, as follows: For each protocolPR and for each initial configurationc, the set of admissible runs ofPR which start fromc defines a tree in a natural way: the root of the tree is the empty run, and each vertex in it denotes a finite prefix of an admissible run; a vertexu in the tree has a sonv iffv is also a prefix of an admissible run, which extendsu by one atomic step.The tree of admissible runs described above may contain infinite paths which are not admissible runs. A set of admissible runs isclosed if for every possible initial configurationc, each path in the tree of admissible runs starting fromc is also an admissible run. Closed sets of runs have the simple combinatorial structure of the set of paths of an infinite tree, which makes them easier to analyze. We introduce a unified method for constructing closed sets of admissible runs by using a model-independent construction of closedschedulers, and then mapping these schedulers to closed sets of runs. We use this construction to provide a unified proof of impossibility of consensus protocols. Ronit Lubitch received her B.Sc. degree in Mathematics and Computer Science from Tel Aviv University in 1989, and her Master degree in Computer Science from the Technion, in 1993. From 1992 she is working in Graffiti Software Industries, which expertise in the design and development of advanced photo realistic rendering, and animation software systems. Shlomo Moran received his B.Sc. and Ph.D. degrees in Mathematics from the Technion in 1975 and 1979 resp. In 1979–1981 he was at the University of Minnesota as a visiting research specialist. In 1981 he joined the Computer Science Department at the Technion, where he is now a full professor. In 1985–1986 he visited at IBM T.J. Watson Research Center. In 1992–1993 he visited at AT&T Bell Laboratories and in Centrum voor Wiskunde en Informatica, Amsterdam. His research interests include distributed computing, Combinatorics and Graph Theory, and Complexity Theory.A preliminary extended version of this paper appeared in the Proceedings of 6-th International Workshop on Distributed Algorithms, Haifa, November 1992This work was supported in part by the Technion V.P.R. fund. Part of this research was conducted while this author was visiting at AT&T Bell Labs at Murray Hill and at CWI, Amsterdam     

On the generalized symmetric cutoff rate for finite-state channels

Finite-state discrete-time channels with equiprobable M-ary inputs are considered. The generating function bound, which is ubiquitously applied to upper-bound the error probability of uncoded signaling over these channels, is used here to lower-bound the corresponding generalized symmetric cutoff rate, which lower-bounds the practically achievable rates and error exponents in these channels with symmetric signaling. The bound accounts for general additive metrics. For the special case of the optimal maximum-likelihood metric, the corresponding bound is shown to be asymptotically tight in the region where the symmetric cutoff rate approaches its maximum value of log₂ M (bits-per-channel use). For a finite-state additive white Gaussian noise (AWGN) channel this feature is used to relate the minimum Euclidean distance of an uncoded symmetric system to the corresponding symmetric cutoff rate. The results are demonstrated for AWGN channels corrupted by linear and nonlinear intersymbol interference. They are also used to assess the efficiency of concatenated coding over the 4-ary AWGN channel where the finite-state mechanism is defined by simple rate 1/2, four-state Ungerboeck 4-AM trellis code     

Processing phonological and semantic ambiguity: Evidence from semantic priming at different SOAs.

Disambiguation of heterophonic and homophonic homographs was investigated in Hebrew using semantic priming. Ambiguous primes were followed by unambiguous targets at 100 msec, 250 msec, and 750 msec stimulus onset asynchrony (SOA). Lexical decision for targets related to the dominant phonological alternatives of heterophonic homographs was facilitated at all SOAs. Targets related to subordinate alternatives were facilitated only at SOAs of 250 msec or longer. When the primes were homophonic homographs, semantic relationship facilitated lexical decision to targets at all SOAs regardless of the dominance of the meaning to which the targets were related. These data can be accounted for by assuming multiple lexical entries for heterophonic homographs, single lexical entries for homophonic homographs, and phonological mediation of accessing meanings. Language-specific factors probably account for the long-lasting activation of subordinate meanings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Power of the independent samples t test under a prevalent psychometric measure distribution.

Studies in psychology often have low power because of inadequate sample size. Thus, recent articles in the Journal of Consulting and Clinical Psychology have suggested making sample size determinations through readily available tables that are based on population normality. Questions have been raised on the use of these power tables because prevalent psychometric distributions, such as the discrete mass at zero with gap that occurs with 1st use or onset variables, are radically nonnormal. In addition to demonstrating the robustness of the independent samples t test with respect to Type I error, the major finding of this study shows that researchers may use these power tables without modification for this radically nonnormal distribution. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Planar collision-type dependence on incident angle and on friction coefficient

This work addresses the ‘hard collision’ approach to the solution of planar, simple non-holonomic systems undergoing a one-point collision-with-friction problem, showing that (i) there are no coherent types of collision whereby forward sliding follows sticking, unless the initial relative tangential velocity of the colliding points vanishes; and (ii) the type of collision can be determined directly, given the collision angle of incidence \(\alpha\) and Coulomb’s coefficient of friction \(\mu\) between the colliding points. The classic hitting rod problem is used to illustrate the \(\alpha \)–\(\mu\) collision-type dependence. Finally, the relation between collision with friction and tangential impact problems in multibody systems is briefly discussed.     

Attaching the fluorine atom to organic molecules using BrF3 and other reagents directly derived from F2

Elemental fluorine is a starting point for nucleophilic fluorinations (e.g., BrF3), radical fluorinations (e.g., F2 under irradiation), and electrophilic fluorinations (e.g., AcOF). All three categories are represented in this Account. Bromine trifluoride, although commercially available, can be readily made from the elements and is a very good source for naked nucleophilic fluoride ions. To minimize radical reactions, an anchor has to be installed in the molecules with which it reacts. Such an anchor is constituted of a soft base such as nitrogen and especially sulfur atoms. This reagent was used for constructing compounds with a CF2, CF3, CHF2, or CF2COOH group in specific sites. F2 itself was used for completing perfluorination of various polyfluoroethers, while the electrophilic acetyl hypofluorite is an excellent tool for introducing a single fluorine atom into organic molecules such as carboxylic acids and nitro compounds.     

Ferroelectric single-crystal nano-rods grown within a nano-porous aluminum oxide matrix

Growing ferroelectric nano single-crystals with uniform polar direction in-vertical to the substrate plane is of high scientific and technological interest for understanding ferroelectric behavior in small dimensions and developing future devices. Single-crystals of Rochelle Salt (RS) and potassium nitrate (PN), with preferred orientation, were grown inside a highly-dense array of aluminum oxide nano-pores, oriented in-vertical to the substrate plane. Preferred orientation was also obtained for potassium niobate crystals. Under certain conditions, nucleation occurred only at the pore bottom due to a tight control over temperature, liquid composition, and pore size. Nucleation at the bottom is necessary for the formation of identically-aligned single-crystals within the pores. Non-linear dielectric behavior was observed in the case of RS and PN crystals inside the pore. The pores stabilize the ferroelectric phase of RS up to 30°C above the upper Curie temperature of bulk (24°C). In the case of PN-filled pores, the crystals grow in the non-ferroelectric orthorhombic phase. Upon applying an electric field of 200 kV/cm, a transition to the ferroelectric phase occurs, and a hysteresis loop appears. This phenomenon was not observed in bulk PN and is attributed to the effect of the hydrostatic pressure applied by the pore walls combined with the applied electric field.