Análisis espacial con agrupamientos kernel ponderados para determinar sectores de riesgo por accidentes de tráfico en zona urbana. Análisis Tunja, Colombia

A method is presented to identify and determine groups with risk sectors due to the greater occurrence of traffic accidents in urban areas as an integral component in road safety management. The methodology was framed in Spatial Analysis with geographic statistics based on Exploratory Data Analysis (AED), Kernel Density Estimation (KDE), and the application of correlation and geoprocessing techniques. The accident data collected between 2015 and 2018 from the urban area of ​​Tunja, Boyacá, Colombia, were the basis for the study of the distribution of events, characterization of clusters, occurrence dynamics and pattern modeling. The definition and delimitation of risks depended on the dispersion or grouping (Hotspots) found with weighted Kernel together with the socio-spatial interrelation of underlying processes due to the territorial dynamics of the sector. The results reveal patterns of events in concentration foci with different levels of risk, in which land uses of opposite characteristics coexist according to their activities [commercial and residential], socioeconomic sectors of low strata with a mixture of arterial road network that by its functionality mobilizes high vehicular and pedestrian flows. Although the analysis is limited to a case study, the findings show a promising perspective in road safety by delimiting risk sites for traffic accidents through the incidence of territorial variables.Se presenta un método para identificar y determinar agrupaciones con sectores de riesgo por mayor ocurrencia de accidentes de tránsito en áreas urbanas como un componente integral en la gestión de seguridad vial. La metodología se enmarcó en el Análisis Espacial con estadística geográfica fundamentada sobre el Análisis Exploratorio de Datos (AED), la estimación Densidad Kernel (KDE), y la aplicación de técnicas de correlación y geoprocesamiento. Los datos de accidentes recopilados entre 2015 a 2018 de la zona urbana de Tunja, Boyacá, Colombia, fueron la base para el estudio de la distribución de eventos, caracterización de agrupaciones, dinámica de ocurrencia y la modelación de patrones. La definición y delimitación de riesgos dependió de la dispersión o agrupamiento (Hotspots) hallados con Kernel ponderado junto con la interrelación socioespacial de procesos subyacentes por la dinámica territorial del sector. Los resultados revelan patrones de eventos en focos de concentración con diferentes niveles de riesgo, en el que coexisten usos de suelo de características opuestas de acuerdo con sus actividades [comercial y residencial], sectores socioeconómicos de estratos bajos con mezcla de red vial arterial que por su funcionalidad moviliza altos flujos vehiculares y peatonales. A pesar de que el análisis se limita a un estudio de caso, los hallazgos muestran una perspectiva prometedora en seguridad vial al delimitar sitios de riesgo por accidentes de tráfico a través de la incidencia de variables territoriales

Reliability of Bell’s Test Conducted with Virtual Reality

Cancellation tasks are commonly used assessment tools to detect unilateral neglect. Bell’s Test, one of the most commonly administered cancellation tasks, requires individuals to quickly and accurately identify “bells” randomly placed in an array of symbols. The reliability of Bells Test conducted with a paper and pencil is well established. A newly developed, commercial software application, allows Bell’s Test to be administered in fully immersive virtual reality environment. PURPOSE: The purpose of this study was to measure the reliability of the Bell’s Test using a virtual reality (VR) system and to establish the level of agreement between the pen-paper and VR administration. METHODS: Fourteen apparently healthy individuals between the age of 24 – 73y volunteered (47.9±20.7y; 166.0±5.2cm; 77.5±16.3kg). Subjects were excluded if they had a history of concussion or had perceptual or visual deficits. Participants completed Bell’s Test a total of four times. The first time, it was completed with a pen-paper (PP). Then, participants completed an initial assessment in VR (VRbase); the same test was administered again in VR one-hour (PostVR1hr) and one-week (PostVR1wk) post baseline. Realization time, total time, and the number of errors committed in the right and left field of view were recorded. Cronbach’s alpha was computed on realization and total time in all VR conditions. Additionally, an ANOVA with repeated measures was used to determine differences in PP, VRbase, PostVR1HR, and PostVR1Wk. The Holms-Sidak method was used to identify pairwise differences. Alpha was set at pa priori. RESULTS: Reliability for realization time for the Bell’s test conducted in VR was acceptable (α=0.79). There was, however, a significant difference between trials (F=6.65; p=0.013). VRbase (29.25±8.11s) was significantly different than PostVR1HR (15.52±4.30; p=0.006). and VRpost1wk (21.24±5.89s; p=0.01). Additionally, PP realization time (15.31±4.25s) was significantly different than PostVR1HR (p=0.02) and PostVR1WK (p=0.03). Reliability for total time for the Bell’s test conducted in VR was good. (α=0.82). There was not a significant difference between the trials (F=4.34; p=0.06) for VRbase(24.1±6.7s), PostVR1HR (45.44±12.6) or VRpost1wk(p=0.06). However, there was a significant difference found in PPtotal time taken and VR1wk with the (p=0.03). The average number of left side omitted bells was 0.50±0.65; 0.07±0.26; 0.07±0.26; 0.14±0.36 for PP, VRbase, Post VR1HR, and PostVR1WK; respectively. The number of bells omitted on the right side was 0.50±0.85, 0.21±0.57, 0.14±0.36, for 0.14±0.36 for PP, VRbase, PostVR1HR, and PostVR1WK; respectively. CONCLUSION: These data indicate that the reliability of the Bell’s Test for the realization time is acceptable, and the total time reliability was good in the virtual reality system. Healthy individuals performing the Bell’s Test in VR show slight improvements one hour after baseline, but there was no difference after one week. More data are needed within different age groups to determine reliability in young and older individuals. Additionally, future studies are required to determine the reliability of Bell’s Test in VR for individuals suffering from neurological injuries or diseases

Effect of different intensities of physical activity on cardiometabolic markers and vascular and cardiac function in adult rats fed with a high-fat high-carbohydrate diet

Background: Physical activity (PA) and diet are 2 lifestyle factors that affect cardiometabolic risk. However, data on how a high-fat high-carbohydrate (HFHC) diet influences the effect of different intensities of PA on cardiometabolic health and cardiovascular function in a controlled setting are yet to be fully established. This study investigated the effect of sedentary behavior, light-intensity training (LIT), and high-intensity interval training (HIIT) on cardiometabolic markers and vascular and cardiac function in HFHC-fed adult rats. Methods: Twelve-week-old Wistar rats were randomly allocated to 4 groups (12 rats/group): control (CTL), sedentary (SED), LIT, and HIIT. Biometric indices, glucose and lipid control, inflammatory and oxidative stress markers, vascular reactivity, and cardiac electrophysiology of the experimental groups were examined after 12 weeks of HFHC-diet feeding and PA interventions. Results: The SED group had slower cardiac conduction (p = 0.0426) and greater thoracic aortic contractile responses (p < 0.05) compared with the CTL group. The LIT group showed improved cardiac conduction compared with the SED group (p = 0.0003), and the HIIT group showed decreased mesenteric artery contractile responses compared with all other groups and improved endothelium-dependent mesenteric artery relaxation compared with the LIT group (both p < 0.05). The LIT and HIIT groups had lower visceral (p = 0.0057 for LIT, p = 0.0120 for HIIT) and epididymal fat (p < 0.0001 for LIT, p = 0.0002 for HIIT) compared with the CTL group. Conclusion: LIT induced positive adaptations on fat accumulation and cardiac conduction, and HIIT induced a positive effect on fat accumulation, mesenteric artery contraction, and endothelium-dependent relaxation. No other differences were observed between groups. These findings suggest that few positive health effects can be achieved through LIT and HIIT when consuming a chronic and sustained HFHC diet

Correlations between central and peripheral changes in anterior corneal topography after myopic LASIK and their implications in postsurgical contact lens fitting

PURPOSE: To investigate the changes in central and peripheral anterior corneal curvatures after myopic laser in situ keratomileusis (LASIK) and to correlate them with the manifest refractive change to discuss how such results could affect post-LASIK corneal topography profiles and midterm stability and their implications in postsurgical contact lens fitting. METHODS: Topographic and refractive data from 18 eyes of 11 patients that had undergone myopic LASIK were collected for 6 months after surgery. Short-term and midterm topographic responses were investigated and correlated with spherical equivalent manifest refractive changes. RESULTS: There was a strong correlation between eccentricity changes and manifest refractive change 15 days after surgery (r = 0.753, P < 0.001), with no significant changes thereafter for the following 6 months (r = 0.148, P = 0.114). A strong linear relationship was found between baseline manifest refraction and changes in corneal curvature at the center (r = 0.810, P < 0.001), 4-mm chord (r = 0.895, P < 0.001), and 6-mm chord (r = 0.696, P < 0.001). Statistically significant changes were also found after the first 15 days (P < 0.005) and showed a regression effect that affects the three zones. In this case, a weaker relationship was found between curvature regression and the final refractive change for the central location (r = 0.412, P = 0.004), 4-mm chord area (r = 0.430, P = 0.003), and 6-mm chord area (r = 0.283, P = 0.023). CONCLUSIONS.: After myopic LASIK, the anterior corneal dioptric power is expected to change, on average, approximately 77% of the attempted spherical equivalent correction at the center; 60% at the 4-mm chord region, where the stronger correlation between topographic and refractive change is found; and 30% at the 6-mm chord area. The paracentral area 4 mm from the center seems to be more likely to predict baseline corneal curvature from manifest refractive change. Some degree of regression in the midterm period is expected to occur after myopic LASIK, which shows a significant correlation with the manifest refractive change. Again, this effect is more evident and more accurately predicted at the 4-mm chord area. The results of the current study are of interest for those fitting contact lenses after myopic LASIK.(undefined

Efecto de la suplementación de Ca, P, Cu, y Zn en hembras puras Cebú.

En el municipio de Coyaima, Colombia, a 330 m.s.n.m., se compara la ganancia de peso en novillas Cebú puras, en pastoreo de angleton, para tratamientos entre una mezcla mineral a base de sal común, fosfato bicálcico, sulfato de cobre y sulfato de zinc (sal experimental, frente a una mezcla mineral comercial (sal testigo). La ganancia por animal por día fué de 484 y 470 gr para la sal ICA y testigo respectivamente. El consumo de sal diaria por animal fué de 41 y 34 gr para las sales ICA y testigo. La diferencia de 9.7 kg por animal, al término de la etapa I, fué significativa estadísticamente. La diferencia de consumo de minerales fué de 2,91 kg representando un 41 por ciento más a favor del grupo experimental. Al concluír el ensayo, la diferencia de ganancia de peso fué de 78 kg a favor del grupo experimental, correspondiente a 3.5 kg por animal, diferencia no significativa estadísticamente, pero de real beneficio económico. Al finalizar el ensayo, 70 por ciento del grupo experimental y 65 por ciento del grupo testigo, presentaron funcionalidad ovárica. Los valores minerales del forraje revelaron aumentos importantes en Ca, P, Mg, K, Zn, Fe, Mn y proteína, y ligeros para Cu, favorables para finales de lluvia. En los análisis del suero sanguíneo no se observaron diferencias importantes intragrupos ni intergrupos para Ca, P, Mg, Cu, Zn. Los análisis de biopsia hepática revelaron aumentos en Mg y Zn y ligera baja en Fe, el Mn aumentó en el grupo testigo, el Cu concluyó norma

Broad-band gravitational-wave pulses from binary neutron stars in eccentric orbits

Maximum gravitational wave emission from binary stars in eccentric orbits occurs near the periastron passage. We show that for a stationary distribution of binary neutron stars in the Galaxy, several high-eccentricity systems with orbital periods in the range from tens of minutes to several days should exist that emit broad gravitational-wave pulses in the frequency range 1-100 mHz. The space interferometer LISA could register the pulsed signal from these system at a signal-to-noise ratio level $S/N>5\sqrt{5}$ in the frequency range $\sim 10^{-3}-10^{-1}$ Hz during one-year observational time. Some detection algorithms for such a signal are discussed.Comment: 17 pages, LATEX, 3 figures, Astronomy Letters, 2002, in press; typos corrected, refference adde

Caracterización molecular de algunas especies y variedades de ñame presentes en la costa atlántica colombiana

En Colombia el ñame (Dioscorea data y Dioscorea rotundata) es un cultivo de importancia para los pequeños productores de la Costa Atlántica. El Programa Colombiano de Biotecnología Agrícola (PBA) de Ñame tiene el objetivo de incrementar la sostenibilidad de grupos de campesinos de la región, adelantando investigaciones participativas en diferentes aspectos relacionados con el cultivo. En el presente trabajo, el objetivo principal fue caracterizar molecularmente las ocho variedades de ñame utilizadas en el PBA, a través de marcadores moleculares tipo AFLP para determinar si existe concordancia entre la taxonomía morfológica establecida para la clasificación de las especies y variedades con la discriminación y agrupación de los individuos por sus perfiles de bandas moleculares aportados por los AFLP Para la obtención de los patrones de AFLP se utilizaron los kits de Gibco-BRL, New York Analysis System I y Analysis System II, siguiendo los manuales de instrucción. Para el análisis estadístico se realizaron matrices de presencia ausencia, se determinaron las similitudes a partir del índice de similaridad de Dice con el paquete estadístico Gel Stats. Posteriormente, las matrices se transformaron en matrices de distancia, y a partir de éstas se construyeron los dendogramas utilizando como estrategia de agrupamientos UPGMA (Unweighted Pare Group Method Averange). Finalmente se realizó una comparación entre matrices utilizando el análisis de permutaciones de Mantel. Los resultados muestran que de las siete variedades de Dioscorea alata analizadas solamente tres de ellas presentan polimorfismos que permiten diferenciarlas. Las otras cuatro se agruparon como una sola variedad.Seven varieties of the Dioscorea alata specie (but only one variety of the Dioscorea rotundata specie) have been morphologically characterised in Colombia. These varieties have been used in the Colombian Yam Agricultural Biotechnology Programme (ABP) to increase the sustainability of groups of poor rural workers from the Colombian Atlantic Coast by providing them with plants having good organoleptic characteristics and increased tuber yield. This work's main objective was the molecular characterisation of those varieties of yam from the Colombian Atlantic Coast used in the ABP, through Amplified Fragment Length Polymorphism (AFLP) molecular markers. This aimed at determining if there is conformity between that morphological taxonomy established for the classification of ABP programme species and varieties with the discrimination and grouping of individuals by their molecular band profiles provided by AFLP Seven varieties of D. alata specie and the sole variety of the D. rotundata specie were characterised. Gibco-BRL, New York Analysis System I and Analysis System II kits were used to obtain AFLP patterns, following handbook instructions. Presence/absence matrices were constructed for the statistical analysis; similarity was determined from the Dice similarity index by using the Gel Stats statistical package. Later matrices became distance matrices and dendograms were constructed from these by using UPGMA (Unweighted Pair Group Method Average) for grouping strategy. Comparison was then made between matrices by using Mantel permutation analysis. The results show that only three of all the seven Dioscorea alata varieties analysed presented polymorphism allowing them to be differentiated. The other four varieties were grouped as a sole variety or belonged to a single variety. These results have great importance for widening information concerning yam in Colombia, particularly for the Colombian ABR since it makes it possible to reduce collection and maintenance costs, leading to information regarding each accession to Colombia's germplasm banks to be increased. This is the first molecular characterisation work carried out in Colombia on yam species (Dioscorea spp.)