2,589 research outputs found
Including Item Characteristics in the Probabilistic Latent Semantic Analysis Model for Collaborative Filtering
We propose a new hybrid recommender system that combines some advantages of collaborative and content-based recommender systems. While it uses ratings data of all users, as do collaborative recommender systems, it is also able to recommend new items and provide an explanation of its recommendations, as do content-based systems. Our approach is based on the idea that there are communities of users that find the same characteristics important to like or dislike a product. This model is an extension of the probabilistic latent semantic model for collaborative filtering with ideas based on clusterwise linear regression. On a movie data set, we show that the model is competitive to other recommenders and can be used to explain the recommendations to the users.algorithms;probabilistic latent semantic analysis;hybrid recommender systems;recommender systems
Effect of pH, Temperature and S02 Concentration on the Malo-Lactic Fermentation Abilities of Selected Bacteria and on Wine Colour
Thirty malo-Iactic bacterial cultures, isolated from red wines from 10 Western Cape wineries, were tested for their malo-Iactic fermentation abilities in Cinsaut wine. Each isolate was tested at S02 concentrations of 34 and 61 mg/C pH levels of 3,5 and 3,8, and temperatures of 15 and 20 °C. The wines were inoculated after alcoholic fermentation, and malo-Iactic fermentation was followed by paper chromatography tests for the following 5 months. At this point the colour of each oottle of wine which had undergone malo-Iactic fermentation, was determined and the colour loss calculated. The lower S02 concentration and higher temperature were significantly more favourable to malo-lactic fermentation. Two of the Leuconostoc oenos isolates completed malo-Iactic fermentation highly significantly more rapidly than nearly all other L. oenos, Lactobacillus and Pediodoccus isolates under the conditions tested. No great differences, few of which were significant, were found amongst the other isolates. The higher S02 concentration was the most important single factor causing colour loss in the experimental wines. The 30 bacterial cultures tested did not produce significantly different losses in colour
Roboethics: Ethics Applied to Robotics
This special issue deals with the emerging debate on robo- ethics, the human ethics ap- plied to robotics. Is a specific ethic applied to robotics truly neces- sary? Or, conversely, are not the gen- eral principles of ethics adequate to answer many of the issues raised by our fieldâs applications? In our opin- ion, and according to many roboticists and human scientists, many novel issues that emerge and many more that will show up in the immediate future, arising from the upcoming marketed robotics products, demand the development of new cultural and legal tools that can provide the crucial answers to the most
sensitive questions
Variation in pattern of mystacial vibrissae in mice: A quantitative study of ICR stock and several inbred strains
We report on the variation in the pattern of mystacial vibrissae in ICR mice, of which one-half of the about 600 animals investigated showed one or more supernumerary whiskers (SWs). The SWs and their folliclesâin all respects identical to the units of the standard pattern except for their smaller sizeâoccurred at a restricted number of sites. In addition, a limited number of mice from two BALB/c strains were analyzed. Half of them also had one or more SWs, but mainly at one site. Mice of the C3H/HeJ and DBA/2J(a) strains were virtually without SWs, whereas animals from the NMRI strain were standard without exception. Nearly all animals of the C57BL/6J strain lacked between 1 and 4 vibrissae, always from one or two of the same adjacent sites. There was a slight overall predominance for the left side of the face to bear SWs and there was no clear-cut association with sex; the entire population was without obvious defects. The sites where extra or lacking whiskers occur are associated with the lines of fusion between the medial and the lateral nasal fold, and between the latter and the maxillary arch. Where tested, we always found a topologic equivalency between the pattern of the whisker follicles and the contralateral pattern of the "barrelsââmultineuronal units in layer IV of the parietal cerebral cortexâwhether the pattern was standard, "enriched,â or lacking in elements. The data presented in this paper provided a basis for several studies carried out subsequently on animals that are the offspring of those characterized here, studies suggesting that the occurrence of supernumerary and of lacking whiskers has a genetic basi
Compression of sub-relativistic space-charge-dominated electron bunches for single-shot femtosecond electron diffraction
We demonstrate compression of 95 keV, space-charge-dominated electron bunches
to sub-100 fs durations. These bunches have sufficient charge (200 fC) and are
of sufficient quality to capture a diffraction pattern with a single shot,
which we demonstrate by a diffraction experiment on a polycrystalline gold
foil. Compression is realized by means of velocity bunching as a result of a
velocity chirp, induced by the oscillatory longitudinal electric field of a 3
GHz radio-frequency cavity. The arrival time jitter is measured to be 80 fs
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