Addressing sight-distance-related safety effects of installing median barriers at horizontal curves of undivided highways under a 3D approach

Concrete barriers are often installed to separate opposing directions of traffic at hazardous horizontal curves on undivided highways in order to avoid frequent types of crashes such as head-on collisions. Whereas this treatment is effective for preventing head-on crashes, they reduce the available sight distance (ASD). The estimation of sight distance is usually performed under a two-dimensional (2D) approach, despite the three-dimensional (3D) nature of facilities. Radius curve, clearance and trajectory location on cross section are the only variables considered under the planar approach, ignoring the spatial component. To overcome this limitation, this study applies a 3D sight distance estimation method, where the sight distance reduction caused by installing barriers is evaluated, contemplating their shape and position in a detailed fully 3D model. The procedure facilitates incorporating mass standardized constructive elements into the highway model. This method consists of a geoprocessing model on a geographic information system (GIS), where the impact of the terrain, the roadway itself, and the road furniture on sight distance is broached. The results evidenced that the ASD outcomes were different under either approach. In addition, the ASD fell below the required stopping sight distance (SSD) of the standards under either approach. A potential application of this method is the analysis of the overall safety effects and the subsequent evaluation of crash modification factors associated to this safety measure

The Application of Statins in the Regeneration of Bone Defects. Systematic Review and Meta-Analysis

This systematic review aims to analyze the effect of the local application of statins in the regeneration of non-periodontal bone defects. A systematic study was conducted with the Pubmed/Medline, Embase, Cochrane Library and Scielo databases for in vivo animal studies published up to and including February 2019. Fifteen articles were included in the analysis. The local application of the drug increased the percentage of new bone formation, bone density, bone healing, bone morphogenetic protein 2, vascular endothelial growth factor, progenitor endothelial cells and osteocalcin. Meta-analyses showed a statistically significant increase in the percentage of new bone formation when animals were treated with local statins, in contrast to the no introduction of filling material or the introduction of polylactic acid, both in an early (4–6 weeks) and in a late period (12 weeks) (mean difference 39.5%, 95% confidence interval: 22.2–56.9, p <0.001; and mean difference 43.3%, 95% confidence interval: 33.6–52.9, p < 0.001, respectively). Basing on the animal model, the local application of statins promotes the healing of critical bone size defects due to its apparent osteogenic and angiogenic effects. However, given the few studies and their heterogenicity, the results should be taken cautiously, and further pilot studies are necessary, with radiological and histological evaluations to translate these results to humans and establish statins’ effec

An analysis of the prevalence of peripheral giant cell granuloma and pyogenic granuloma in relation to a dental implant

Background: The aim of the present investigation was to evaluate the literature recurrence of peripheral giant cell granuloma and pyogenic granuloma associated with dental implants. It's important to know the characteristics present in these lesions and possible effects on the prognosis of dental implants. Methods: An electronic search without time restrictions was done in the databases: PubMed/Medline. With the keywords "Granuloma" OR "Granuloma, Giant Cell" OR "peripheral giant cell" OR "Granuloma, Pyogenic" AND "Dental implants" OR "Oral implants". Results: After applying the inclusion and exclusion criteria, a total of 20 articles were included, which reported 32 lesions (10 pyogenic granulomas, 21 peripheral giant cell granulomas and one peripheral giant cell granuloma combined with peripheral ossifying fibroma, all associated with implants). According to our review, these lesions are more frequent in males and in the posterior region of the mandible. Both excision and curettage of the lesion, compared to only excision, presented similar recurrences (40%). Explantation of the implant was performed in 41% of cases without additional recurrences. The results are not statistically significant when comparing one lesion to the other in terms of explantation (p = 0.97), recurrence (p = 0.57) or bone loss (p = 0.67). Conclusions: The main therapeutic approach is tissue excision. The lesions show a high recurrence rate (34.4%), which often requires explantation of the associated implant. This recurrence rate is not affected by curettage after excision

Haloalkalitolerant Actinobacteria with capacity for anthracene degradation isolated from soils close to areas with oil activity in the State of Veracruz, Mexico

The use of native strains of microorganisms from soils is an excellent option for bioremediation. To our knowledge, until now there has been no other group working on the isolation of Actinobacteria from contaminated soils in Mexico. In this study, samples of soils close to areas with oil activity in the State of Veracruz, Mexico, were inoculated for the isolation of Actinobacteria. The strains isolated were characterized morphologically, and the concentrations of NaCl and pH were determined for optimal growth. Strain selection was performed by the detection of a phylogenetic marker for Actinobacteria located at the 23S rRNA gene, followed by species identification by sequencing the 16S rRNA gene. Several haloalkalitolerant Actinobacteria were isolated and identified as: Kocuria rosea, K. palustris, Microbacterium testaceum, Nocardia farcinica and Cellulomonas denverensis. Except for C. denverensis, the biomass of all strains increased in the presence of anthracene. The strains capacity to metabolize anthracene (at 48 h), determined by fluorescence emission, was in the range of 46&ndash;54%. During this time, dihydroxy aromatic compounds formed, characterized by attenuated total reflectance Fourier transform infrared spectroscopy bands of 1205 cm&ndash;1 and 1217 cm&ndash;1. Those Actinobacteria are potentially useful for the bioremediation of saline and alkaline environments contaminated with polycyclic aromatic hydrocarbon compounds. [Int Microbiol 2016; 19(1):15-26]Keywords: Kocuria &middot; Microbacterium &middot; haloalkalitolerant Actinobacteria &middot; anthracene degradation &middot; State of Veracruz, Mexic

Frecuencia de prolongación del intervalo QTc en adultos infectados con VIH de Paraguay en 2020

Introduction: the prolonged QTc interval predisposes to serious arrhythmias. Various medications, including antiretrovirals, can prolong it. The objectives were to determine the demographic, clinical characteristics and the frequency of the prolonged QTc interval in patients with HIV. Methods: we conducted a prospective, observational study with a control group. Men and women, over 18 years of age, with HIV infection, who attended the National Hospital (Itauguá, Paraguay) during 2020, were included. Medical students acted as a control group. All subjects who did not give their consent and those with arrhythmias were excluded. Demographic, clinical, laboratory variables and 12-channel electrocardiogram at rest were measured. The study was approved by the Ethics Committee of the Universidad Privada del Este (Paraguay). Results: 39 HIV patients and 39 healthy controls entered the study. The mean age of the cases was 37 ± 11 years, being 59% male. The most frequent comorbidity in the cases was obesity (7.6%). The mean values ​​of urea, creatinine, K, Ca and Mg in the cases were in the normal range. Prolonged QTc was detected in 18% of the cases and in 0% of the controls. The subjects with the electrocardiographic alteration were all on antiretroviral and multiple antibiotic treatment known to be associated with prolonged Qtc. Conclusion: the frequency of prolonged QTc in HIV patients was 18% and in healthy controls it was 0%. Regular monitoring of the electrocardiogram is recommended in HIV patients receiving drugs that prolong the QT interval.Introducción: el intervalo QTc prolongado predispone a arritmias graves. Diversos medicamentos, entre ellos los antirretrovirales, pueden prolongarlo. Los objetivos fueron determinar las características demográficas, clínicas y la frecuencia del intervalo QTc prolongado en pacientes con VIH. Métodos: estudio observacional, prospectivo, con grupo control. Se incluyeron varones y mujeres, mayores de 18 años, portadores de infección por VIH, que acudieron al Hospital Nacional (Itauguá, Paraguay) durante 2020. Actuaron como grupo control los estudiantes de Medicina. Se excluyeron todos los sujetos que no dieron su consentimiento y los portadores de arritmias. Se midieron variables demográficas, clínicas, laboratoriales y electrocardiograma de 12 canales en reposo. El estudio contó con la aprobación del Comité de Ética de la Universidad Privada del Este (Paraguay). Resultados: ingresaron al estudio 39 pacientes con VIH y 39 controles sanos. La edad media de los casos fue 37 ± 11 años, siendo 59% del sexo masculino. La comorbilidad más frecuente en los casos fue la obesidad (7,6%). Los valores medios de urea, creatinina, K, Ca y Mg en los casos se hallaban en rango normal. Se detectó 18% de QTc prolongado en casos y 0% en los controles. Estos sujetos con alteración electrocardiográfica se hallaban todos en tratamiento antirretroviral y antibiótico múltiple de conocida asociación con QTc prolongado. Conclusión: la frecuencia de QTc prolongado en pacientes con VIH fue del 18% y en controles sanos fue del 0%. Se recomienda el control periódico del electrocardiograma en pacientes con VIH en tratamiento con fármacos que prolongan el intervalo QT

Sight distance analysis of urban intersections using geospatial technologies

La distancia de visibilidad es un factor clave en la seguridad vial y, por tanto, en el diseño geométrico de carreteras. La estimación de la visibilidad disponible en carreteras existentes es necesaria para asegurar que los conductores cuenten con suficiente información para llevar a cabo maniobras requeridas para la conducción. Por otro lado, es necesario que tanto aquellos usuarios que transitan por la calzada como aquellos que utilizan las vías ciclistas y aceras puedan contar con una buena visibilidad mutua en lugares donde converjan maniobras conflictivas. La estimación de distancias de visibilidad, durante la fase de explotación, puede llevarse a cabo in situ o fuera del campo, utilizando de modelos digitales. La tendencia actual en investigación es la propuesta de mediciones fuera del campo. Por ello, los conjuntos de datos provenientes de distintas tecnologías geoespaciales, específicamente sistemas LiDAR o fotogramétricos, tienen gran presencia en publicaciones actuales. Estas contribuciones se enfocan en la evaluación del entorno viario tal como es, tratando fundamentalmente la detección de obstrucciones. Por otro lado, las metodologías existentes están eminentemente orientadas a la evaluación de las visibilidades disponibles para las maniobras de parada, adelantamiento, e intersección en la calzada y considerando únicamente al conductor como observador principal. Esta tesis presenta una metodología para la evaluación de las distancias de visibilidad requeridas en intersecciones. El trabajo se centra en las intersecciones urbanas, dada la afluencia de usuarios vulnerables en estos entornos. A esto se le suma la gran cantidad de elementos en sus márgenes, con sus respectivos impactos en la visibilidad. Se han empleado datos obtenidos mediante sistemas de mapeado con sensores LiDAR y herramientas para el cálculo de la visibilidad desarrolladas en sistemas de información geográfica. Se han analizado 3 tramos de carretera y 6 intersecciones de diferente tipología. En primer lugar, se identificaron las tareas necesarias para obtener modelos digitales que representen el entorno viario de forma fidedigna a partir de datos LiDAR. Dado que estos datos requieren de múltiples procesamientos, se examinaron distintos programas informáticos de tratamiento de datos LiDAR y su idoneidad para llevar a cabo las tareas necesarias para modelar la vía. Entre una totalidad de 21 programas preliminarmente considerados, 7 fueron examinados en detalle. Estos últimos se evaluaron empleando criterios definidos por la organización internacional de estandarización (ISO) para medir la calidad en uso de los softwares. El programa de modelado digital MDTopX resultó con mayor idoneidad para el fin ya que, entre otras cosas, facilitaba la extracción automatizada de potenciales obstrucciones del entorno viario como objetos 3D. A continuación, se emplearon dos sistemas móviles y un sistema estático para la adquisición de los datos espaciales de una selección de intersecciones urbanas. Seguido se evaluaron las visibilidades requeridas en dichas intersecciones considerando las trayectorias no sólo de los conductores, sino también de ciclistas, usuarios de vehículos de movilidad personal y peatones. Para ello se desarrolló una herramienta de procesamiento geoespacial que considera las trayectorias de dos usuarios distintos a la hora de estimar la visibilidad de cruce. Esta herramienta permite designar uno o dos usuarios como observadores principales. Los resultados evidenciaron que pequeños cambios en la ubicación de los observadores en la calzada resultan en diferencias significativas en la visibilidad. Por otro lado, algunas obstrucciones impedían que los peatones pudieran ver vehículos acercándose a los cruces peatonales. Por ello, se ha propuesto la creación de escenarios, o alteraciones de la realidad, en las que se elimina, modifica o reemplaza el elemento que obstruye la visibilidad. Después de modificar este elemento, se puede repetir la evaluación y comparar estos resultados con la visibilidad disponible en el escenario real. Distintas comparaciones llevadas a cabo entre escenarios reales y propuestos (simulados) arrojaron visibilidades estadísticamente diferentes. Finalmente, se realizó un estudio del efecto de los distintos factores incluidos en la estimación de visibilidad disponible. Factores como la altura del ojo del observador y su posición en el carril, el tipo de intersección evaluada y el tipo de sistema LiDAR empleado, fueron comparados utilizando diseños factoriales completos con repetición. Las variables consideradas resultaron estadísticamente significativas. ----------ABSTRACT---------- The safe and efficient operation of all highway facilities requires the provisioning of adequate sight distances. During the design stage, sight distances are crucial in dimensioning alignment and profile elements. Existing roads, on the other hand, require their available sight distances to be compared to the required ones to ensure that motorists have enough information about the road and its conditions to perform basic driving maneuvers. Similarly, vulnerable road users sharing the roadway, and those in their dedicated facilities, require proper visibility of potentially conflicting trajectories and fixed elements. Available sight distance estimations can be carried out in situ or off-site by means of detailed, updated, and accurate digital models of the road environment. Current research has focused on off-site methodologies. Hence, the significant presence of road modeling data, especially geospatial, in the literature of the subject. Most of the data used to model the road come from photogrammetry or LiDAR-based systems. Previous studies have focused on evaluating the road environment as is, aiming at obstruction detection rather than the evaluation or proposal of solutions. On the other hand, most studies have considered motorists as main observers. This work introduces a novel methodology to evaluate sight distances required at urban road intersections. Apart from being a complex road section, urban intersections usually host a great number of vulnerable road users. To this, we can add a significant amount and variety of urban furniture, public transportation, and city utility elements, all with specific impacts on visibility. The proposed procedure employs LiDAR-derived data and geoprocessing tools to estimate sight distances and overall visibility. These tools were developed in geographic information system software. A total of three two-lane highways (for software testing) and six urban intersections were analyzed. First, the tasks required to generate digital models from LiDAR data were identified. As LiDAR systems produce extensive data, several processing steps are necessary between their acquisition and the modeling phase. Owing to that, several LiDAR processing software suits, tools, libraries, etc., were evaluated to identify those that could ease the overall process. Out of 21 software suits initially considered, seven were examined in detail using criteria specified by the international standards organization (ISO). Ultimately, the digital modeling software MDTopX proved more suitable because it eased the extraction of road elements as 3D elements. Next, two mobile mapping systems and a static LiDAR mechanism were used to evaluate selected urban intersections. These evaluations considered the trajectories of motorists, cyclists, personal mobility device users, and pedestrians with and without restricted mobility. For this purpose, a tool was developed within geographic information software. This tool takes two different trajectories as primary input, allowing evaluations within the roadway or in the dedicated facilities of vulnerable road users (VRU). It estimates sight distances, intervisibility between two observers, and overall visibility. Results evidenced how small changes in the trajectories of observers produce statistically significant differences in the resulting sight distances. Some of the obstructions identified prevented motorists from spotting pedestrians about to cross the roadway. Therefore, a procedure to handle these obstructions is introduced. This procedure proposes the creation of scenarios where the obstacles can be removed, modified, or replaced. After this, the sight distance estimation can be rerun, and the results provided by the two models can be compared. Several comparisons showed statistically different results between the actual scenario and the modified ones. Finally, a factorial analysis was used to evaluate the impact of those parameters considered in the estimation of visibility. The Factors included were the observer’s height and lane placement, the type of intersection under evaluation, and the type of LiDAR used to obtain the data. This evaluation showed that all the parameters considered had a statistically significant impact on the resulting visibility

Modeling Urban Road Scenarios to Evaluate Intersection Visibility

Road safety is key to sustainable mobility. Rapid technological advances have allowed several road safety-related analyses, previously performed in situ, to be conducted virtually. These virtual analyses benefit understanding of how roads operate and how users perceive them. Additionally, they facilitate the assessment of several parameters that are fundamental to road design and operation. The available sight distance (ASD) is one of these parameters that, if not provided adequately, could alter the proper functioning of roads. This study presents a framework to assess the impact of certain features on visibility. First, the ASD is estimated using a geographic information system (GIS)-based procedure with LiDAR-derived three-dimensional (3D) models. Afterward, obstructions are detected and categorized. If the obstruction cannot be removed, their redesign or relocation is simulated to re-run the analysis. These simulations are performed using 3D city objects, and their results are statistically evaluated, providing evidence as to their effects on visibility. The results proved that the procedure helped achieve the efficient use of roadside space, while including safety concerns. Additionally, this study reflects the need for more inspections on the impact of on-street parking on drivers’ fields of view.This article is published as González-Gómez, Keila, Derrick K. Rollins, and María Castro. "Modeling Urban Road Scenarios to Evaluate Intersection Visibility." Sustainability 14, no. 1 (2022): 354. DOI: 10.3390/su14010354. Copyright 2021 by the authors. Attribution 4.0 International (CC BY 4.0). Posted with permission

Evaluating Pedestrians' Safety on Urban Intersections: A Visibility Analysis

Overall visibility plays a key role in the safety of pedestrians. Despite its importance, verifying the right provisioning of sufficient available sight distances among pedestrians and vulnerable road users (VRUs) is not a prevalent practice. On top of that, the pursuit for more sustainable modes of transportation has promoted the establishment of different shared mobility services which are prone to increase walking and, thus, the number of pedestrians and other VRUs in urban settings. With the intention of verifying how car-centered designs perform for non-motorized users, a 3D procedure that evaluates the visibility of pedestrians and other users is presented and applied to specific cases in Madrid, Spain. The proposed solution employs virtual trajectories of pedestrians with mobility impairments and without them, cyclists, and personal transportation device riders. Their visibility was assessed around the functional area of urban intersections, including zones where possible jaywalking practices might occur. The evaluation was performed three-dimensionally, making use of LiDAR data, GIS tools, and 3D objects. Results show the impact of street furniture location on visibility, the distinctive influence of vegetation on the lines of sight of each observer, and how design parameters that were intended to improve motorized traffic could affect VRU

Suitability Testing of LiDAR Processing Software Aimed at 3-D Sight Distance Estimations

Sight distance estimations are significant components of road safety analyses. Drivers ought to have enough available sight distance (ASD) in order to safely perform basic driving maneuvers. When not performed in situ, estimating ASD on existing roads normally requires up-to-date representations of the roads’ geometric properties as well as the execution of roadway design related tasks and geospatial analysis operations; hence, several software products are needed to carry out these calculations throughout their entire workflow. Nowadays, LiDAR based Mobile Mapping Systems (MMS) have been intensively put into use to gather data needed to accomplish many transportation applications. In spite of their many benefits, MMS produce fair volumes of point cloud data which add some complexity to the processing stage in terms of software, computational requirements and interoperability. This paper analyses software capabilities, in terms of suitability and performance, of computer programs capable of LiDAR data processing tasks. The main goal of this evaluation is to gauge their aptness to deliver data needed to perform ASD estimations. To accomplish this, a thorough review of available literature on sight distance analyses was conducted to get a depiction of frequently demanded software tasks and deliverables and based on that, different volumes of point cloud were processed with a variety of software solutions in order to test their appropriateness for the purpose from early stages of the workflow to final calculations. This research highlights how the truly potential of LiDAR data for performing highway safety related analyses relies heavily upon the usage of efficient and powerful software tools