Impact of Statistical Multiplexing on Voice Quality in Cellular Networks

This paper examines the quality of transmission of voice over cellular, packet-switched networks. The medium access mechanism in the uplink is simulated under various statistical multiplexing scenarios in order to assess the effect of front-end clipping on voice quality. Moreover, the simulation is implemented in a real-time demonstration platform utilized to acquire subjective indicators of voice quality by performing Mean Opinion Score (MOS) tests. Results from the MOS tests are reported, and an analysis of the obtained speech samples is presented. Finally, the results are summarized and potential further directions for the simulation tool and the speech models are discussed.     

Effective Computation of Rational Approximants and Interpolants

This paper considers the problem of effective algorithms for some problems having structured coefficient matrices. Examples of such problems include rational approximation and rational interpolation. The corresponding coefficient matrices include Hankel, Toeplitz and Vandermonde-like matrices. Effective implies that the algorithms studied are suitable for implementation in either a numeric environment or else a symbolic environment.The paper includes two algorithms for the computation of rational interpolants which are both effective in symbolic environments. The algorithms use arithmetic that is free of fractions but at the same time control the growth of coefficients during intermediate computations. One algorithm is a look-around procedure which computes along a path of closest normal points to an offdiagonal path while the second computes along an arbitrary path using a look-ahead strategy. Along an antidiagonal path the look-ahead recurrence is closely related to the Subresultant PRS algorithm for polynomial GCD computation. Both algorithms are an order of magnitude faster than alternative methods which are effective in symbolic environments.     

Supported gold clusters and cluster-based nanomaterials: characterization, stability and growth studies by in situ GISAXS under vacuum conditions and in the presence of hydrogen

This contribution is devoted to study of the thermal stability and growth of gold nanoparticles supported on SiO₂/Si(111) and Al₂O₃/SiO₂/Si(111) as a function of initial cluster size, support material and level of surface coverage. Experimental evidence for “flipping” of two dimensional cluster structures from vertical orientation to horizontal on the support is presented.     

Links between physical fitness and cardiovascular reactivity and recovery to psychological stressors: A meta-analysis.

A meta-analysis of published studies with adult human participants was conducted to evaluate whether physical fitness attenuates cardiovascular reactivity and improves recovery from acute psychological stressors. Thirty-three studies met selection criteria; 18 were included in recovery analyses. Effect sizes and moderator influences were calculated by using meta-analysis software. A fixed effects model was fit initially; however, between-studies heterogeneity could not be explained even after inclusion of moderators. Therefore, to account for residual heterogeneity, a random effects model was estimated. Under this model, fit individuals showed significantly attenuated heart rate and systolic blood pressure reactivity and a trend toward attenuated diastolic blood pressure reactivity. Fit individuals also showed faster heart rate recovery, but there were no significant differences in systolic blood pressure or diastolic blood pressure recovery. No significant moderators emerged. Results have important implications for elucidating mechanisms underlying effects of fitness on cardiovascular disease and suggest that fitness may be an important confound in studies of stress reactivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The importance of a common in-group identity in ethnically diverse groups.

The purpose of this study was to examine the effects of a common in-group identity in attenuating the negative effects of ethnic dissimilarity. Specifically, it was hypothesized that a common in-group identity would moderate the relationship between ethnic dissimilarity and satisfaction with coworkers. Data were gathered from 87 persons working in groups. Moderated regression analysis provided support for the hypothesis, in that when a common in-group identity was not present, demographic dissimilarity was related to less satisfaction, but when a common in-group identity was present, there was a positive relationship between ethnic dissimilarity and coworker satisfaction. Further, for ethnically dissimilar persons, coworker satisfaction was higher when a common in-group identity was present than when it was not. Results are discussed in relation to the study's contribution to social psychology and diversity management literature. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A temperature-dependent model for the complex dielectric function of GaAs

In this work, we discuss a temperature-dependent model for the complex dielectric function for GaAs valid for the temperature range 31°C ≤ T ≤ 634°C. We describe our model, which is an extension of the critical point parabolic band method. This is a phenomenological method which is based on the physical processes occurring in the semiconductor, and has been previously demonstrated for composition-dependent models of the dielectric function for lattice-matched materials systems. We demonstrate the quality of the model in fitting optical data for individual temperatures, and compare our results to other established models. The data used for each fitting ranges from 1.25 to 4.5 eV. Using results obtained from the individual fits, we generate a temperature-dependent model that is valid for the range of temperatures given above. Also, we show how this model can be used to accurately determine the temperature (±2.3°C) of a material whose dielectric response has been obtained but was not included when generating the model.     

Differential dyeing cotton. Part 2-stoichiometry of interaction with acid and direct dyes

The stoichiometry of interaction of both acid and direct dyes with cotton modified with a reactive cationic reagent has been examined. In the case of the acid dyes adsorption is principally by a specific site mechanism and gives a 1:1 ratio between cationic sites on the cotton and sulphonate groups on the dyes, although some diffuse adsorption occurs with the more hydrophobic dyes. The direct dyes show a much greater amount of diffuse adsorption in addition to specific site adsorption. The results show that the presence of the cationic sites enhance the amount of dye taken up by diffuse adsorption and a mechanism for this is proposed.     

Arc minimization in finite-state decoding graphs with cross-word acoustic context

Recent approaches to large vocabulary decoding with weighted finite-state transducers have focused on the use of determinization and minimization algorithms to produce compact decoding graphs. This paper addresses the problem of compiling decoding graphs with long span cross-word context dependency between acoustic models. To this end, we extend the finite-state approach by developing complementary arc factorization techniques that operate on non-deterministic graphs. The use of these techniques allows us to statically compile decoding graphs in which the acoustic models utilize a full word of cross-word context. This is in significant contrast to typical systems which use only a single phone. We show that the particular arc-minimization problem that arises is in fact an NP-complete combinatorial optimization problem. Heuristics for this problem are then presented, and are used in experiments on a Switchboard task, illustrating the moderate sizes and runtimes of the graphs we build.