Learning automata-based solutions to the nonlinear fractional knapsack problem with applications to optimal resource allocation.

This paper considers the nonlinear fractional knapsack problem and demonstrates how its solution can be effectively applied to two resource allocation problems dealing with the World Wide Web. The novel solution involves a "team" of deterministic learning automata (LA). The first real-life problem relates to resource allocation in web monitoring so as to "optimize" information discovery when the polling capacity is constrained. The disadvantages of the currently reported solutions are explained in this paper. The second problem concerns allocating limited sampling resources in a "real-time" manner with the purpose of estimating multiple binomial proportions. This is the scenario encountered when the user has to evaluate multiple web sites by accessing a limited number of web pages, and the proportions of interest are the fraction of each web site that is successfully validated by an HTML validator. Using the general LA paradigm to tackle both of the real-life problems, the proposed scheme improves a current solution in an online manner through a series of informed guesses that move toward the optimal solution. At the heart of the scheme, a team of deterministic LA performs a controlled random walk on a discretized solution space. Comprehensive experimental results demonstrate that the discretization resolution determines the precision of the scheme, and that for a given precision, the current solution (to both problems) is consistently improved until a nearly optimal solution is found--even for switching environments. Thus, the scheme, while being novel to the entire field of LA, also efficiently handles a class of resource allocation problems previously not addressed in the literature.     

Study of high efficiency of evaluation of a PDP in authorization service

In authorization service, the efficiency of evaluation of a PDP(policy decision point) is a key issue that affects the efficiency of authorization service. However, the efficiencies of evaluation of many PDPs available are frequently influenced by the factors of conditions in rules. Said Marouf et al put forward a method in which the evaluation speed can be increased by adjusting the rules in policies according to user history access records. This paper analyzes the shortcomings of this method in real-time applications, and proposes that the rules order in policies can be instantaneously adjusted by user history access records and indexes as well as self-adaptation are added to a PDP so that the evaluation speed can be increased substantially. Experimental results indicate that when there are 9795 rules in a PDP, the evaluation time and the time consumption taken for a PDP applied with indexes and self-adaptation to complete an authorized operation call are shortened by 93.33％ and 76.32％ respectively, compared with those for a PDP which is not applied with indexes and self-adaptation. When the number of repeat visits from the same user is 7, the time consumption taken for a PDP applied with indexes and adaptation to complete an authorized operation call is shortened by 24.29％ compared with that for a PDP which is applied with indexes only.     

CPR artifact removal from human ECG using optimal multichannel filtering

The purpose of this study was to assess whether the artifacts presented by precordial compressions during cardiopulmonary resuscitation could be removed from the human electrocardiogram (ECG) using a filtering approach. This would allow analysis and defibrillator charging during ongoing precordial compressions yielding a very important clinical improvement to the treatment of cardiac arrest patients. In this investigation we started with noise-free human ECGs with ventricular fibrillation (VF) and ventricular tachycardia (VT) records. To simulate a realistic resuscitation situation, we added a weighted artifact signal to the human ECG, where the weight factor was chosen to provide the desired signal-to-noise ratio (SNR) level. As artifact signals we used ECGs recorded from animals in asystole during precordial compressions at rates 60, 90, and 120 compressions/min. The compression depth and the thorax impedance was also recorded. In a real-life situation such reference signals are available and, using an adaptive multichannel Wiener filter, we construct an estimate of the artifact signal, which subsequently can be subtracted from the noisy human ECG signal. The success of the proposed method is demonstrated through graphic examples, SNR, and rhythm classification evaluations.     

Nonparametric 1-D temperature restoration in lossy media using Tikhonov regularization on sparse radiometry data

Microwave thermometry has the potential to characterize thermal gradients in lossy materials down to a few centimeters depth. The problem of retrieving temperature profiles from sets of brightness temperatures is studied using Galerkin expansion of one-dimensional (1-D) temperature profiles combined with Tikhonov regularization and predefined boundary conditions. From a priori knowledge of the temperature field shape, smooth Chebyshev polynomials are used as basis functions in the series expansion. The proposed estimator does not require iterative calculations that are normally performed using conventional numerical methods for signal parameter estimation and is, thus, very fast. Noise effects versus bandwidth limitations (smoothness of solutions) are studied in terms of four performance indexes defined in the text. In general, statistical spread of the temperature estimator increases with increasing number of Chebyshev polynomials. Systematic deviation from true values (bias) decreases as the number of Chebyshev polynomials increases. Results show that smooth temperature profiles can be reproduced using 6-7 Chebyshev polynomials. With additional constraints such as boundary conditions and maxima localization, a three-frequency-band radiometric scan is sufficient to produce acceptable results in regions with low thermal gradients. As the spatial variability of the 1-D temperature profile increases, more radiometric bands (5-6) are required to provide nonbiased estimates.     

Does the aging of tenured academic staff affect the research performance of universities?

This paper examines the common contentions that the collective aging of tenured academic staff has negative effects on research performance of universities due to (a) negative effects of aging in itself, and (b) to a lack of newcomers who could revitalise the research. Data on academic staff and research at Norwegian universities over two decades have been used to examine these contentions. While older staff published less than their younger colleagues two decades ago, no differences in productivity are found today. Furthermore, during this period, a large increase in the number of post-doctoral fellows and PhD students has taken place, compensating for the aging of tenured staff.     

Strength and conflicting valence in the measurement of food attitudes and preferences

There is a trend in current attitude research to move away from a simple uni-dimensional view of attitude, towards examining a more multivariate concept of attitude. An extensive array of attitudinal properties or dimensions has been provided, defined and categorised as ‘attitude strength’. Attitude strength has only recently been adapted as a conceptual framework for research in marketing and consumer studies. Our objective in this paper is to introduce some of the attitude strength concepts and literature in order to improve the measure and understanding of research dealing with measurement of food preferences, perceived food quality and satisfaction with food products, food suppliers, etc. The paper takes a particular focus upon problems in comprehending the middlemost choice or neutrality when measuring attitude items along a traditional bipolar semantic differential or a bipolar hedonic preference scale. Through several propositions, we have outlined how future research should note that both attitude ambivalence (mixed feelings) and non-attitude (lack of confidence in evaluation) could be threats to comprehending the middlemost response alternative on a questionnaire as neutral when measuring food attitudes or preferences in the traditional way. Our approach should also deal with some of the shortcomings of analysing attitude–behaviour consistency when modelling food consumption behaviour.     

Visual results of progressive multifocal posterior chamber intraocular lens implantation

PURPOSE: To evaluate corrected and uncorrected near, intermediate, and distance visual acuities in eyes with a progressive multifocal intraocular lens (IOL) and to determine the effect of the lens on contrast sensitivity. SETTING: Multicenter study. METHODS: This prospective study comprised 59 eyes that had uneventful cataract surgery and implantation of a progressive multifocal IOL at three study centers. Uncorrected and corrected near, intermediate, and distance visual acuities were measured, as was contrast sensitivity at different frequencies. One year results are reported. Patient satisfaction was assessed using a subjective questionnaire. RESULTS: Distance visual acuity improved from 0.13 Snellen lines uncorrected and 0.23 with best correction preoperatively to 0.77 and 0.96 lines, respectively, postoperatively. Uncorrected preoperative near acuity was 13.28 Jaeger lines and best corrected acuity, 8.93 lines. These improved to 4.75 and 2.69 lines, respectively. The differences between visual acuity at intermediate distances and best distance and near acuities were not significant. Patient satisfaction was highest with vision under good light conditions and when viewing larger objects. CONCLUSION: Visual performance with the multifocal progressive IOL was adequate at various distances without additional correction. It was less satisfactory under poor light conditions.     

UGA codon position affects the efficiency of selenocysteine incorporation into glutathione peroxidase-1

A UGA codon and a selenocysteine insertion sequence in the 3'-untranslated region are the only established mRNA elements necessary for selenocysteine (Sec or U) incorporation during translation. These two elements, however, do not universally confer efficient Sec incorporation. The objective of this study was to systematically examine the effect of UGA codon position on efficiency of Sec insertion. In a glutathione peroxidase-1 (F-GPX1) expression vector, the UGA at the native position (U47) was mutated to a cysteine codon, and codons for Ser-7, Ser-12, Ser-18, Ser-29, Ser-45, Ser-93, Cys-154, Val-172, Ser-178, and Ser-195 were individually mutated to UGA and transiently expressed in COS-7 cells. 75Se incorporation at the 11 positions was 31, 72, 54, 105, 90, 100, 146, 135, 13, 11, and 43%, respectively, of 75Se incorporation at U47, suggesting that Sec is more efficiently incorporated at UGA codons positioned in the middle of the coding region rather than close to the 5' or 3' ends. Ribonuclease protection showed that these differences were not due to differences in mRNA level. When the green fluorescence protein (GFP) coding region was placed in-frame at the 5' or 3' ends of the coding region in F-GPX1 to produce chimeric 50-51-kDa GFP/GPX1 proteins, Sec incorporation at UGA codons, formerly close to the 5' or 3' ends, was increased to levels comparable to the UGA at U47. Insertion of GFP after the UAA-stop was just as effective in increasing Sec insertion efficiency as GFP inserted before the stop. These studies used a recombinant expression model that incorporated Sec at non-native UGA codons at rates equal to those of endogenous glutathione peroxidase-1 and showed that the efficiency of Sec incorporation can be modulated by UGA position; Sec incorporation at high efficiency appears to require that the UGA be >21 nucleotides from the AUG-start and >204 nucleotides from the selenocysteine insertion sequence element.     

符合ZigBee协议的RF解决方案的实现

IEEE802.15,4/ZigBee是针对无线监测和控制系统的需求而设计的射频标准.设计者可以利用符合ZigBee标准的开发平台,进行ZigBee产品的开发,该平台由硬件和软件组成.这将大大缩短产品上市时间,并减少系统设计及ZigBee认证所需的费用.