Flat 3-webs of degree one on the projective plane

The aim of this work is to study global $3$-webs with vanishing curvature. We wish to investigate degree $3$ foliations for which their dual web is flat. The main ingredient is the Legendre transform, which is an avatar of classical projective duality in the realm of differential equations. We find a characterization of degree $3$ foliations whose Legendre transform are webs with zero curvature.Comment: 14 page

Template assisted surface micro microstructuring of flowable dental composites and its effect on the microbial adhesion properties

Despite their various advantages, such as good esthetic properties, absence of mercury and adhesive bonding to teeth, modern dental composites still have some drawbacks, e.g., a relatively high rate of secondary caries on teeth filled with composite materials. Recent research suggests that microstructured biomaterials surfaces may reduce microbial adhesion to materials due to unfavorable physical material–microbe interactions. The objectives of this study were, therefore, to test the hypotheses that (i) different surface microstructures can be created on composites by a novel straightforward approach potentially suitable for clinical application and (ii) that these surface structures have a statistically significant effect on microbial adhesion properties.Peer ReviewedPostprint (author's final draft

Diseño de un observador y un controlador de velocidad de un motor DC por modos deslizantes

En este artículo se presenta una estructura de estimación y control de estados mediante modos deslizantes para un modelo lineal. Se presenta un sistema mecánico de un Motor DC, al cual se le diseñaran un observador y un controlador deslizante de primer y segundo orden. Los resultados se comparan con un diseño de un PID. Los dos diseños se prueban ante cambios de referencia, perturbaciones y ruido. In this paper a structure for estimation and control of states using sliding modes is presented for a linear model. A mechanical system of a DC motor is presented with a designed observer and a sliding controller of first and second order. The results are compared with a design of a PID. The two designs are tested against reference changes, disturbances and noise. — In this paper a structure for estimation and control of states using sliding modes is presented for a linear model. A mechanical system of a DC motor is presented with a designed observer and a sliding controller of first and second order. The results are compared with a design of a PID. The two designs are tested against reference changes, disturbances and noise. Keywords — Dc Motor, Observer, Sliding modes, State spaceUniversidad Nacional de ColombiaColciencia

Diseño de un Observador y un Controlador de velocidad de un motor DC por modos deslizantes

En este artículo se presenta una estructura de estimación y control de estados implementando las normas básicas de diseño de observadores y controladores mediante modos deslizantes para un modelo lineal. Se presenta un sistema mecánico de un Motor DC, al cual se le diseñaran un observador y un controlador deslizante de primero y segundo orden. Los resultados se comparan con un diseño de un PID. Los dos diseños se prueban ante cambios de referencia, perturbaciones y ruido.Universidad Nacional de ColombiaColcienciasBanco Mundia

MsWH: A multi-sensory hardware platform for capturing and analyzing physiological emotional signals

This paper presents a new physiological signal acquisition multi-sensory platform for emotion detection: Multi-sensor Wearable Headband (MsWH). The system is capable of recording and analyzing five different physiological signals: skin temperature, blood oxygen saturation, heart rate (and its variation), movement/position of the user (more specifically of his/her head) and electrodermal activity/bioimpedance. The measurement system is complemented by a porthole camera positioned in such a way that the viewing area remains constant. Thus, the user''s face will remain centered regardless of its position and movement, increasing the accuracy of facial expression recognition algorithms. This work specifies the technical characteristics of the developed device, paying special attention to both the hardware used (sensors, conditioning, microprocessors, connections) and the software, which is optimized for accurate and massive data acquisition. Although the information can be partially processed inside the device itself, the system is capable of sending information via Wi-Fi, with a very high data transfer rate, in case external processing is required. The most important features of the developed platform have been compared with those of a proven wearable device, namely the Empatica E4 wristband, in those measurements in which this is possible

Penyagolosa trails: From ancestral roads to sustainable ultra-trail race, between spirituality, nature, and sports. A case of study

The organization of an open-air sporting event involves a series of challenges. People are drawn by the desire to do sport, preferably in close contact with nature, so as to complement healthy lifestyles, and in search of air purity. Sporting organizations are increasingly searching for new locations that do not only attract athletes, but spectators and companions too. Races in natural parks provide the additional benefit of doing sport in a unique space, usually a transmitter of simplicity, pure air, and tranquillity. Organizing a mountain race in a natural park implies some issues. These are areas of great environmental richness that must be protected. Natural parks are places of individual recreational activity. Within the running phenomenon, a new type of mountain race has appeared: the hiking-oriented pilgrimage, in which athletes travel ancestral paths, pilgrimage routes thus combining sport practice with spirituality. This paper aims to analyse all the actions and policies that were carried out for the peaceful integration and coexistence of two totally different events that coincide physically and temporally: the Penyagolosa Trails race, and the Peregrins de les Useres, an ancestral pilgrimage that is carried out by each and every one of the towns belonging to the Penyagolosa Natural Park. The objective is to demonstrate the sustainability of the project thanks to the collective effort and the goodwill of the interested parties, in a way that produces a mutual benefit

Validity of Two Methods for Assessing Oral Health Status of Populations

Objective : This investigation assessed two methods for estimating epidemiologic indicators of oral health status among children: (1) a visual-only screening, performed independently by a dental hygienist and a registered nurse; and (2) a parent- or guardian-completed questionnaire. The indicators included dichotomous variables measuring dental caries and treatment needs, presence of sealants, injuries to the anterior teeth, and dental fluorosis. Methods : Following training and calibration, data were collected over an eight-day period in April 1994 among 632 elementary schoolchildren (aged 5 to 12 years) in Monticello, Georgia. Both screening and questionnaire findings were compared pairwise with results from visual-tactile examinations done by a dentist. Validity, represented by sensitivity, specificity, and predictive values, was assessed for screening results from the dental hygienist, the nurse, and the parent-completed questionnaire. Results : Validity was high for screening for caries and treatment needs (>90% for sensitivity, specificity, and predictive values in a sample having 30% to 40% prevalence). Less valid data — mainly an effect of false negatives — were obtained for fluorosis, injuries, and presence of sealants. No significant difference in validity was observed between the nurse and the dental hygienist. One-third of respondents to the questionnaire did not know if their children needed fillings (a proxy for untreated decay) or had received sealants; only knowledge of restorations was comparable to results from screening. Intraexaminer reliability for the two screeners ranged from 85 to 100 for percent agreement and 0.70 to 0.93 for kappa scores. Conclusions : Screening by dental hygienists or nurses can provide valid data for surveillance of dental caries and treatment needs. Training for visual assessment of fluorosis and injuries must be improved to diminish the proportion of false negatives. A parent-completed questionnaire is less effective than visual screening for evaluating oral health status in children.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66163/1/j.1752-7325.1997.tb02977.x.pd