Hybrid Recommender Systems: Survey and Experiments

Recommender systems represent user preferences for the purpose of suggesting items to purchase or examine. They have become fundamental applications in electronic commerce and information access, providing suggestions that effectively prune large information spaces so that users are directed toward those items that best meet their needs and preferences. A variety of techniques have been proposed for performing recommendation, including content-based, collaborative, knowledge-based and other techniques. To improve performance, these methods have sometimes been combined in hybrid recommenders. This paper surveys the landscape of actual and possible hybrid recommenders, and introduces a novel hybrid, EntreeC, a system that combines knowledge-based recommendation and collaborative filtering to recommend restaurants. Further, we show that semantic ratings obtained from the knowledge-based part of the system enhance the effectiveness of collaborative filtering.     

Numerical integration methods

The numerical evaluation of an integral is a frequently encountered problem in electromagnetic theory. This is particularly the case when the current distribution or near field of a scatterer or antenna is required, in which case the far-field approximation cannot be employed. A comparative study of several numerical quadrature techniques is presented. The superiority of a variable interval-width technique based on Romberg's method will be demonstrated for an integral typical of those which arise in scattering and radiation from thin-wire structures.     

Neuropsychological changes in adolescents with insulin-dependent diabetes.

Assessed the neurobehavioral status of 40 12–19 yr olds with a long history (at least 3 yrs) of insulin-dependent diabetes mellitus and of 40 demographically similar nondiabetic adolescents. A detailed social and medical history was obtained from parents, and the degree of recent metabolic control was determined by examining the glycosolated hemoglobin values of diabetic Ss. Ss under age 16 yrs were given 7 subtests of the WISC—R; Ss aged 16 yrs and older were given the same subtests from the WAIS. Ss also completed tests that assessed associative learning and memory; visuospatial ability; speed, dexterity, and visuomotor integration; CFF; and self-concept. Results show that diabetics performed within normal limits on all tests, although significant between-groups differences did appear on measures of verbal intelligence, visuomotor coordination, and CFF. Although it could be argued that these results are indicative of structural brain damage, the possibility is discussed that the differences observed may be a function of transient metabolic abnormalities at the time of testing or, alternately, may be a reflection of the behavioral changes associated with having a life-threatening illness. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dichhaptic recognition of shapes and letters in children.

[Correction Notice: An erratum for this article was reported in Vol 37(4) of Canadian Journal of Psychology Revue Canadienne de Psychologie (see record 2007-03779-001). The legends for Figures 1 and 2 should read as follows: Figure 1: Verbal and nonverbal stimuli. Reprinted by permission from Laterality: Functional Asymmetry in the Intact Brain, by M.P. Bryden. New York: Academic Press, 1982. All rights reserved. Figure 2: Apparatus for dichhaptic presentation of verbal and nonverbal stimuli. Reprinted by permission from Laterality: Functional Asymmetry in the Intact Brain, by M.P. Bryden. New York: Academic Press, 1982. All rights reserved.] Previous investigations of tactual asymmetry have generally used long presentation times and few have controlled responding order. The present study used dichhaptic presentation of letter and nonsense shapes, a 2-sec exposure time, and a controlled order of response to investigate tactual asymmetry in 40 8-, 10-, 12-, and 14-yr-olds. Ss were tested individually in a single session after being assigned to 1 of 2 groups. One group received the verbal material first, the other group the nonverbal material first. Nonsense shapes showed a significant left-hand superiority, whereas letters showed no consistent hand differences, suggesting that right hemisphere involvement was greater in the shapes task. No consistent age effects were found. The only significant sex differences involved a trend toward a greater left-hand (right-hemisphere) effect for males (N?=?20) than females on the shapes. (French abstract) (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of stimulus control treatment of sleep-onset insomnia.

Examined the components responsible for the efficacy of the stimulus control treatment of sleep-onset insomnia. 47 college students with sleep-onset insomnia were assigned to 1 of 5 treatment conditions (stimulus control, noncontingent control, countercontrol, temporal control, and waiting list). Ss were instructed not to expect improvement until after the 4th treatment session. Only stimulus control and a treatment violating the associative aspects of stimulus control produced significantly greater improvement in reported latency to sleep onset than the waiting-list condition. Results are discussed in terms of several possible explanations for improvement due to so-called stimulus control treatment for insomnia. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Natural occurrence of zearalenone and trichothecene toxins in maize-based animal feeds in zambia

A year-long collection of maize-based animal feed samples from the National Milling Company and mouldy maize collected from farmers fields near Lusaka were analysed for Fusarium mycotoxins. In the survey, 148 samples were tested for zearalenone, deoxynivalenol and nivalenol, and 60 samples for T-2 toxin and diacetoxyscirpenol. Zearalenone was present up to 0.6 mg kg^?1 in 17% of the feed samples, and deoxynivalenol was found at I-0 mg kg^?1 in 1.4 % of these samples. This is the first report of these toxins in animal feeds in Zambia. Zearalenone was also found in 57.6 % of the 33 mouldy maize samples collected at levels ranging from 0.08 to 6.0 mg kg^?1 (mean concentration 1.11 mg kg^?1), and 49.5% of these samples contained deoxynivalenol at levels ranging from 0.5 to 16.0 mg kg^?1 (mean concentration 5.56 mg kg ^?1). T-2 toxin and diacetoxyscirpenol were not detected.     

Evaluating the applicability of a modified toxicity characteristic leaching procedure (TCLP) for the classification of cementitious wastes containing lead and cadmium

Having the toxicity characteristic leaching procedure (TCLP) as a starting point, this study examined the effect of the various leaching parameters on the leaching of Pb and Cd from cementitious wastes. Using modified TCLP procedures, the parameters investigated were the acid concentration, leaching duration, particle size of the crushed waste, liquid to solid ratio, and the acid type. The main finding was that the final leachate pH controls the leachability of metals due to its influence on their solubility. The high alkalinity of cementitious waste buffers the leachate at a pH where most metals become insoluble. The TCLP was found to result in an unrealistic condition for cementitious wastes due to the high resultant leachate pH.