Link Slab Details and Materials

This report contains the findings of a synthesis study on the use of link slabs to eliminate intermediate joints in bridges of Indiana. The study was conducted under the sponsorship of the Joint Transportation Research Program. The motivation for the study was to investigate this promising technique to mitigate the damage associated with expansion joints that has long been recognized as a persistent and costly issue negatively impacting the bridge service life. The report summarizes the background information and motivation for the study. It also provides a description of the report organization. The results of an extensive literature review of DOTs’ experience related to the use of this system and main research findings are presented as well as construction practice and examples of application. The results of the analysis of a bridge in Indiana where the link slab system has been implemented are presented. The bridge connecting the State Road 68 over the Interstate 64 was selected as a representative bridge based on the analysis of the inspection. A parametric study on the effects of various parameters was conducted to evaluate the effect of support conditions and debonded length on the stress distribution and potential crack initiation in link slabs. Each variable was investigated separately to isolate its effect. Two bridge structures were investigated in this study. The first structure (Case 1) represents a bridge structure rehabilitated using link slabs. A second bridge structure (Case 2) with the same geometrical and material properties, but with a continuous and fully bonded deck, was also included in the parametric study for comparison purposes. This structure simulated new bridge construction

Short- and mid-term evaluation of the use of electric vehicles in urban freight transport collaborative networks: a case study

Despite its negative impacts, freight transportation is a primary component of all supply chains. Decision makers have considered diverse strategies, such as Horizontal Collaboration (HC) and the usage of alternative types of vehicles, to reduce overall cost and the related environmental and social impacts. This paper assesses the implementation of an electric fleet of vehicles in urban goods distribution under HC strategy between carriers. A biased randomisation based algorithm is used to solve the problem with a multi-objective function to explore the relationships between both delivery and environmental costs. Real data from the city of Bogota, Colombia are used to validate this approach. Experiments with different costs and demands projections are performed to analyse short- and medium-term impacts related to the usage of electric vehicles in collaborative networks. Results show that the optimal selection of vehicle types depends considerably on the time horizon evaluation and demand variation.This work has been partially supported by the Spanish Ministry of Economy and Competitiveness (TRA2013-48180-C3-P and TRA2015-71883-REDT) and the Ibero-American Program for Science and Technology for Development (CYTED2014-515RT0489). Likewise, we want to acknowledge the support received by the Special Patrimonial Fund from Universidad de La Sabana (Colombia) and the doctoral grant from the UOC-Open University of Catalonia (Spain)

Updated Big Bang Nucleosynthesis Bounds on Long-lived Particles from Dark Sectors

As electromagnetic showers may alter the abundance of Helium, Lithium, and Deuterium, we can place severe constraints on the lifetime and amount of electromagnetic energy injected by long-lived particles. Considering up-to-date measurements of the light element abundances that point to $Y_p=0.245\pm 0.003$,$({\rm D/H})= (2.527\pm 0.03)\times 10^{-5}$,$(^7{\rm Li/H})=1.58 ^{+0.35}_{-0.28} \times 10^{-10}$, $(^6{\rm Li/^7 Li})=0.05$, and the baryon-to-photon ratio obtained from the Cosmic Microwave Background data, $\eta=6.104 \times 10^{-10}$, we derive upper limits on the fraction of electromagnetic energy produced by long-lived particles. Our findings apply to decaying dark matter models, long-lived gravitinos, and other non-thermal processes that occurred in the early universe between $10^2-10^{10}$ seconds.Comment: 7 pages, 3 figure

Encontro casual na região central do Texas fornece informações sobre a ecologia da estivação de Siren nettingi (Caudata: Sirenidae)

Siren spp. costumam ser vertebrados dominantes nas áreas úmidas que ocupam e são conhecidas por estivar quando essas áreas úmidas secam. Considerações práticas limitam as observações in situ de indivíduos em estivação. Em 12 de outubro de 2021, descobrimos por acaso um agregado em estivação de Siren nettingi no condado de Bastrop, Texas, Estados Unidos. Essas salamandras foram escavadas em solo compacto e rochoso adjacente a uma estrada de caliche, em profundidades que variavam entre ~0,2 e 1,5 m. A vegetação dominante nesse local incluía Ulmus crassifolia, Persicaria sp. e várias espécies de gramíneas. Recuperamos 140 indivíduos, dos quais sete foram resgatados e 133 foram capturados vivos. Medimos 115 deles quanto ao comprimento rostro-cloacal (SVL) e observamos que o agregado era dominado por jovens. Estimamos uma densidade de estivação de 2,33 indivíduos/m2 que é comparável às densidades estimadas para populações sem estivação. No entanto, como não houve monitoramento para esse estudo, provavelmente tenha ocorrido um evento de mortalidade em massa. Portanto, sugerimos que a construção de estradas no habitat preferido seja considerada uma ameaça às populações dessas salamandras.Siren spp. are often dominant vertebrates in the wetlands they occupy and are known to estivate when such wetlands dry up. Practical considerationslimit in-situ observations of estivating individuals. On 12 October 2021, we incidentally discovered an estivating aggregate of Siren nettingi in Bastrop County, Texas, USA. These salamanders were excavated from compact, rocky soil adjacent to a caliche road, at depths that ranged between ~0.2 to 1.5 m. The dominant vegetation at this site included Ulmus crassifolia, Persicaria sp., and various grass species. We recovered 140 individuals of which seven were salvaged and 133 were captured live. We measured 115 of these for snout–vent length (SVL) and observed the aggregate was predominated by juveniles. We estimated an estivation density of 2.33 sirens/m2 that is comparable to densities estimated for non-estivating populations. However, in-lieu of monitoring that was in place for this study, we expect a mass mortality event would have likely occurred. We therefore suggest that roadway construction in preferred habitat be considered as a threat to siren populations

MAPA DE AMENAZA POR CRECIENTES SÚBITAS EN LA MICROCUENCA LA VIUDA, CHITAGÁ, COLOMBIA

Cada día es de gran importancia el análisis de la representación de las componentes hidrológicas y geotécnicas de los cauces cercanos a una zona urbana, dado que hay municipios que se encuentran en crecimiento y que presentan amenazas naturales y deben realizar estudios de zonificación de amenazas por fenómenos naturales que ayuden a la planificación de su desarrollo; las crecientes súbitas son uno de los fenómenos naturales de mayor ocurrencia, por las condiciones climáticas como es el caso de la emergencia ocurrida en el 2015, municipio de Chitagá, Colombia, donde se presentaron desbordamientos de quebradas, causando pérdidas económicas y daños ambientales. La quebrada La Viuda ocupa un área de 2,385km2 y una longitud del cauce principal de 5,337 Km con una altura de 2284 m.s.n.m, en cuya vertiente se identificaron usos del suelo agrícola, ganadería. El objeto principal de la investigación fue analizar la amenaza por crecientes súbitas de la quebrada La Viuda. Para ello, se recopiló información básica, características morfométricas, curvas IDF, hietogramas, hidrógramas, identificación de los puntos de muestreo de sedimentos, aforo y nivel, se establecieron ocho (8)estaciones de muestreo en la parte media y baja de la microcuenca. Se obtuvo que la pendiente promedio de la zona de estudio es de 36.26 %; y se encuentran sedimentos heterométricos incluyendo Depósitos coluviales por deslizamientos, aluviales y sustratos arcillo-limosos. La tendencia a la generación de crecientes repentinas está condicionada por factores permanentes como la naturaleza, la geología, la morfología y la vegetación natural; y en primer orden las características de las precipitaciones (tipo, intensidad, duración, distribución, etc. Por otra parte, a partir de las curvas IDF se estableció que a menor tiempo de duración mayor es la intensidad en función del periodo de retorno; se cuenta con un caudal promedio de 0.053m3/s que es bajo, pero en épocas de alta pluviosidad se presentan crecientes súbitas. Los sedimentos que predominan en el cauce son arenas mal gradadas. Además, el cauce presenta mayor tendencia a sedimentarse que a presentar socavación en su mayoría de los tramos

Fundamentos para el diseño e implementación de un equipo para realizar pruebas de audiometría

El objetivo de este artículo es el de mostrar los fundamentos teóricos necesarios que se requieren para el diseño e implementación de un equipo didáctico para realizar pruebas de audiometría