Binarized support vector machines

The widely used Support Vector Machine (SVM) method has shown to yield very good results in Supervised Classification problems. Other methods such as Classification Trees have become more popular among practitioners than SVM thanks to their interpretability, which is an important issue in Data Mining. In this work, we propose an SVM-based method that automatically detects the most important predictor variables, and the role they play in the classifier. In particular, the proposed method is able to detect those values and intervals which are critical for the classification. The method involves the optimization of a Linear Programming problem, with a large number of decision variables. The numerical experience reported shows that a rather direct use of the standard Column-Generation strategy leads to a classification method which, in terms of classification ability, is competitive against the standard linear SVM and Classification Trees. Moreover, the proposed method is robust, i.e., it is stable in the presence of outliers and invariant to change of scale or measurement units of the predictor variables. When the complexity of the classifier is an important issue, a wrapper feature selection method is applied, yielding simpler, still competitive, classifiers

The socle of a Leavitt path algebra

In this paper we characterize the minimal left ideals of a Leavitt path algebra as those ones which are isomorphic to principal left ideals generated by line point vertices, that is, by vertices whose trees do not contain neither bifurcations nor closed paths. Moreover, we show that the socle of a Leavitt path algebra is the two-sided ideal generated by these line point vertices. This characterization allows us to compute the socle of some algebras that arise as the Leavitt path algebra of some row-finite graphs. A complete description of the socle of a Leavitt path algebra is given: it is a locally matricial algebra.Comment: 13 pg

Changes in Protective Behavioral Strategies and Alcohol Use among College Students

Background—Protective behavioral strategies (PBS) are specific cognitive-behavioral strategies designed to reduce alcohol consumption and resulting negative consequences. A host of studies have examined the cross-sectional relationship between such strategies and alcohol use in the high-risk population of United States college students, but prospective studies on the construct are lacking. The primary purposes of this study were to determine if PBS use prospectively predicted subsequent alcohol use/alcohol-related problems and if changes in PBS use were associated with less alcohol use and fewer problems. Methods—Data were examined from 521 heavy drinking college students (60% male, 84% White, mean age = 18.9 years). Participants completed questionnaires assessing alcohol use, alcohol-related problems, and PBS use at baseline, 6-month, and 12-month follow-ups. Results—Analysis of residualized change scores indicated that increases in some PBS across time were associated with less alcohol use and fewer alcohol-related problems at follow-up. Findings regarding the prospective relationship between PBS use and subsequent alcohol use/ problems were equivocal. Discussion—Results from the study suggest that PBS may have value in alcohol-related interventions among college students. Clinicians who help clients increase their use of PBS may help those clients increase the probability of drinking less and experiencing fewer alcohol-related problems in the future

New Viverrinae (Carnivora: Mammalia) from the basal Middle Miocene of Arrisdrift, Namibia

A new genus and species of viverrid of modern type, Orangic!is gariepensis, is described from the basal Middle Miocene locality of Arrisdrift in southern Namibia. It is the earliest known representative of the subfamily Viverrinae from Africa. Detailed examination of the mongoose-like carnivores of the early Miocene of Africa, hitherto all assigned to the family Viverridae, reveals that none of them are related to this group.The Council's Research Committee, University of the Witwatersrand; National Research Foundation (NRF); Palaeo-Anthropology Scientific Trust (PAST); Museo Nacional de Ciencias Naturales, CSIC, Madrid DGICYT projects PB 95-0113 and PB95-0014; Spanish Agency for International Cooperation (AECI

Older adults and sport and physical activity professionals in Spain

Presence of monitors in physical activities and sports practiced by adults older than 64 years of age in Spain is analyzed in this research. The objective of this study is to determine the existence of monitors in relation to the sociodemographic features of older adults, the size of municipalities, the activities practiced, and the organizations where they are performed. The methodology used included a cross-sectional survey applied to a sample of older adults in Spain. The most relevant conclusions are that the presence of monitors in physical activities and sports practiced by older adults is dominant (63.8%), hence, their importance, and that the presence of monitors is higher for women (81.3%) than for men (37.5%). In addition, it is concluded that the bigger the municipality the higher the tendency to have more instructors. Regarding the type of activity, wide diversification is obtained; finally, there is a larger presence of monitors in sports entities (87.5%) and nursing homes (79.5%)