All Else Being Equal Be Empowered

The original publication is available at www.springerlink.com . Copyright Springer DOI : 10.1007/11553090_75The classical approach to using utility functions suffers from the drawback of having to design and tweak the functions on a case by case basis. Inspired by examples from the animal kingdom, social sciences and games we propose empowerment, a rather universal function, defined as the information-theoretic capacity of an agent’s actuation channel. The concept applies to any sensorimotoric apparatus. Empowerment as a measure reflects the properties of the apparatus as long as they are observable due to the coupling of sensors and actuators via the environment.Peer reviewe

Bump formation in a binary attractor neural network

This paper investigates the conditions for the formation of local bumps in the activity of binary attractor neural networks with spatially dependent connectivity. We show that these formations are observed when asymmetry between the activity during the retrieval and learning is imposed. Analytical approximation for the order parameters is derived. The corresponding phase diagram shows a relatively large and stable region, where this effect is observed, although the critical storage and the information capacities drastically decrease inside that region. We demonstrate that the stability of the network, when starting from the bump formation, is larger than the stability when starting even from the whole pattern. Finally, we show a very good agreement between the analytical results and the simulations performed for different topologies of the network.Comment: about 14 page

Prevalence and severity of dental caries among American Indian and Alaska Native preschool children

Objectives: To describe the Indian Health Service (IHS) oral health surveillance system and the oral health status of American Indian and Alaska Native (AI/AN) children aged 1‐5 years. Methods: A stratified probability sample of IHS/tribal sites was selected. Children were screened by trained examiners at community‐based locations including medical clinics, Head Start, preschools, kindergarten, and Women, Infants, and Children (WIC). Data collection was limited to the primary dentition and included number of teeth present plus number of teeth with cavitated lesions, restorations, and extracted because of decay. Number of molars with sealants and urgency of need for dental care data were also obtained. Statistical analyses were performed with SAS (SAS Institute Inc., Cary, NC, USA). Sample weights were used to produce population estimates based on selection probabilities. Results: A total of 8,461 AI/AN children 12‐71 months of age were screened at 63 IHS/tribal sites, approximately 7 percent of the estimated IHS user population of the same age. Overall, 54 percent of the children had decay experience, 39 percent had untreated decay, 7 percent had primary molar sealants, 36 percent needed early or urgent dental care, and 6 percent needed urgent dental care. The mean of decayed, missing, or filled teeth was 3.5 (95 percent confidence interval, 3.1‐3.9). The prevalence of decay experience increased with age; 21 percent of 1‐year‐olds and 75 percent of 5‐year‐olds had a history of caries. When stratified by IHS area, there were substantial differences in the oral health of preschool children. Conclusions: The results confirm that in the United States, AI/AN children served by IHS/tribal programs are one of the racial/ethnic groups at highest risk of caries.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93514/1/j.1752-7325.2012.00331.x.pd

MODELING OF THERMAL PROFILE INSIDE GUARDED HOT PLATE APPARATUS

Abstract Guarded hot plate apparatus (GHP) is a convenient tool to measure low thermal conductivities of insulating materials. Investigated material is placed between two plates (hot and cold) maintained at desired temperatures. As a consequence of temperature gradient, heat flow through the material occurs. Based upon Fourier law and knowledge of a power of hot plate heater coefficient of thermal conductivity can be determined. Taking into account only conductive mechanism of heat transfer simplified model of temperature profile in GHP is presented in this paper. Model realized in MATLAB allows investigating the influence of many parameters (including geometry of GHP apparatus itself) on the desired temperature profile

Polynomial evaluation over finite fields: new algorithms and complexity bounds

An efficient evaluation method is described for polynomials in finite fields. Its complexity is shown to be lower than that of standard techniques when the degree of the polynomial is large enough. Applications to the syndrome computation in the decoding of Reed-Solomon codes are highlighted.Comment: accepted for publication in Applicable Algebra in Engineering, Communication and Computing. The final publication will be available at springerlink.com. DOI: 10.1007/s00200-011-0160-

Shannon Meets Carnot: Generalized Second Thermodynamic Law

The classical thermodynamic laws fail to capture the behavior of systems with energy Hamiltonian which is an explicit function of the temperature. Such Hamiltonian arises, for example, in modeling information processing systems, like communication channels, as thermal systems. Here we generalize the second thermodynamic law to encompass systems with temperature-dependent energy levels, $dQ=TdS+dT$, where $$ denotes averaging over the Boltzmann distribution and reveal a new definition to the basic notion of temperature. This generalization enables to express, for instance, the mutual information of the Gaussian channel as a consequence of the fundamental laws of nature - the laws of thermodynamics

On Convergence Properties of Shannon Entropy

Convergence properties of Shannon Entropy are studied. In the differential setting, it is shown that weak convergence of probability measures, or convergence in distribution, is not enough for convergence of the associated differential entropies. A general result for the desired differential entropy convergence is provided, taking into account both compactly and uncompactly supported densities. Convergence of differential entropy is also characterized in terms of the Kullback-Liebler discriminant for densities with fairly general supports, and it is shown that convergence in variation of probability measures guarantees such convergence under an appropriate boundedness condition on the densities involved. Results for the discrete setting are also provided, allowing for infinitely supported probability measures, by taking advantage of the equivalence between weak convergence and convergence in variation in this setting.Comment: Submitted to IEEE Transactions on Information Theor

A Remark on Unified Error Exponents: Hypothesis Testing, Data Compression and Measure Concentration

Let A be finite set equipped with a probability distribution P, and let M be a “mass” function on A. A characterization is given for the most efficient way in which A n can be covered using spheres of a fixed radius. A covering is a subset C n of A n with the property that most of the elements of A n are within some fixed distance from at least one element of C n , and “most of the elements” means a set whose probability is exponentially close to one (with respect to the product distribution P n ). An efficient covering is one with small mass M n (C n ). With different choices for the geometry on A, this characterization gives various corollaries as special cases, including Marton’s error-exponents theorem in lossy data compression, Hoeffding’s optimal hypothesis testing exponents, and a new sharp converse to some measure concentration inequalities on discrete spaces

Thresholds in layered neural networks with variable activity

The inclusion of a threshold in the dynamics of layered neural networks with variable activity is studied at arbitrary temperature. In particular, the effects on the retrieval quality of a self-controlled threshold obtained by forcing the neural activity to stay equal to the activity of the stored paterns during the whole retrieval process, are compared with those of a threshold chosen externally for every loading and every temperature through optimisation of the mutual information content of the network. Numerical results, mostly concerning low activity networks are discussed.Comment: 15 pages, Latex2e, 6 eps figure

Provisional Assessment of Candidate High-Temperature Thermal Conductivity Reference Materials in the EMRP “Thermo” Project

This article describes the provisional assessment of a short list of four candidate high-temperature thermal conductivity reference materials in a European research project, “Thermo.” These four candidate materials are low-density calcium silicate, amorphous silica, high-density calcium silicate, and exfoliated vermiculite. Based on initial tests on material composition and microstructure changes, dimensional stability, mechanical stability, chemical stability and uniformity, the best two candidate materials that would be considered for further detailed characterization in the next stage are low-density calcium silicate and high-density calcium silicate. These two materials are dimensionally, mechanically, and chemically stable, which are more robust and easier to handle than others. However, the specimens need to be selected to meet the requirement for material uniformity in terms of density, i.e., density variation within 2%