Large cities are less efficient for sustainable transport: The ABC of mobility

The distance travelled by car in a city has many negative impacts on its population, including pollution, noise and the use of space. Yet, quantifying the motorisation of urban mobility is a serious challenge, particularly across cities of different regions. Here we model the number of kilometres travelled by different modes of transport in a city by aggregating active mobility (A), public transport (B) and cars (C), thus expressing the modal share of a city by its ABC triplet. Data for over 800 cities across over 60 countries is used to model kilometres travelled by car and its relationship with city size. Our findings suggest that although public transport is more prominent in large cities, it is insufficient to reduce the distance travelled by car users within the city and, ultimately, their emissions. For cities outside the US, results show that although the proportion of journeys by car decreases in larger cities, distances become more prolonged, thus experiencing more distance travelled by car. When a city doubles its size, it has 87\% more car journeys, but they are 41% longer, thus experiencing 2.6 times more vehicle kilometres travelled. Further, by matching cities of similar size inside and outside the US, we estimate that cities in the US have 2.3 times more vehicle kilometres travelled than cities elsewhere.Comment: 14 pages, 6 figure

Validación de un instrumento de medición de ambiente escolar para docentes Colombianos

Este estudio explora la validez y fiabilidad de un instrumento de medición del ambiente escolar suministrado a 3610 docentes de las Instituciones Educativas oficiales de la ciudad de Medellín – Colombia en 2011. El análisis factorial exploratorio multinivel permitió establecer que a través de 20 reactivos el instrumento evalúa cuatro dimensiones de ambiente escolar a nivel individual: comunicación de la Institución Educativa hacia los docentes y comunicación de los docentes hacia los padres, nivel de participación en las decisiones de la Institución Educativa, respeto-seguridad emocional y expectativas académicas. A nivel grupal, los mismos reactivos permiten medir una dimensión general de ambiente escolar. Por tanto, los resultados sugieren que el instrumento permite establecer diferencias entre Instituciones Educativas en términos de ambiente escolar.This study explores the validity and reliability of a school environment instrument supplied to 3160 teachers from Medellin – Colombia public schools in 2011. The multilevel factorial analysis allowed establishing that through 20 reactives, the instrument evaluates four school environment dimensions at individual level: communication from the school to the teachers and communication from the teachers to the parents, participation level into the school decisions, respect-emotional security and academic expectations. At the group level, the same reactives allowed measuring a general school environment dimension. Therefore, results suggested the instrument permits to establish differences between schools in school environment terms

Aspiration of an extracted molar : case report

Q4Q3Reporte de caso581-583A case of aspiration of an extracted molar is presented. The main objective of this paperis to provide dental colleagues with an educational framework on foreign-body aspirationto help prevent delayed diagnosis of such events in the future

Diagnóstico microbiológico de harina de huesos procesada en Antioquia y Cundinamarca.

Se analizaron 100 muestras de harina de huesos vaporizadas y calcinadas, haciendo recuento de microorganismos aerobios mesófilos, coliformes, clostridios sulfito reductores y hongos. También se efectuó el aislamiento de Salmonella y la clasificación de los diferentes géneros de hongos. Se compararon los recuentos de las harinas de huesos calcinadas con los recuentos de las harinas de huesos vaporizadas, tomando como límites para microorganismos presentes, los establecidos por la Estación Experimental de Kiel. Se hizo Análisis de varianza y prueba de rango múltiple de Duncan. Los recuentos en las harinas de huesos vaparizados resultaron altos y muy altos, comparados con las harinas de huesos calcinadas, cuyos recuentos fueron normales y altos. Los géneros de hongos más frecuentemente aislados fueron Penicillium sp., Mucor sp. y Aspergillus sp. El porcentaje de aislamiento de Salmonella sp. fue bajo, la cual, en su mayoría, fue aislada de la harina de hueso vaporizad

Resource allocation model for a computer system

This article describes a simulation for resource allocation. As a particular case, it describes how would be the assignment in an ad hoc network. We present the results of a simulation allocating resources from one system (communications network) to another system (agent collections). In the description of the model first shows the behavior of the allocation of resources towards the nodes depending on the usefulness of the network and the satisfaction of the agents. Based on the mathematical model of the tragedy of the commons, the behavior of the system is shown. The usefulness and satisfaction of the system are measured. Resource allocation is modeled as an interaction. The computational model Interaction Nets is used as the basis of the simulation

OpenFOAM Numerical Simulations with Different Lid Driven Cavity Shapes

The finite volume method have been developed to solve the Navier-Stokes equations with primitive variables and non dimensional form. This work examine the classical benchmark problem of the lid-driven cavity at a different Reynolds range (Re = 10,100,400, 1000, 2000, 3200) and several cavity geometries. The cavity configurations include square cavity, skewed cavity, trapezoidal cavity and arcshaped cavity. The flow is assumed laminar and solved in a uniform mesh. A CFD tool with its solvers (icoFoam) will be used for this study

Defining a research agenda for layperson prehospital hemorrhage control: A consensus statement

Importance: Trauma is the leading cause of death for US individuals younger than 45 years, and uncontrolled hemorrhage is a major cause of trauma mortality. The US military\u27s medical advancements in the field of prehospital hemorrhage control have reduced battlefield mortality by 44%. However, despite support from many national health care organizations, no integrated approach to research has been made regarding implementation, epidemiology, education, and logistics of prehospital hemorrhage control by layperson immediate responders in the civilian sector.Objective: To create a national research agenda to help guide future work for prehospital hemorrhage control by laypersons.Evidence review: The 2-day, in-person, National Stop the Bleed (STB) Research Consensus Conference was conducted on February 27 to 28, 2019, to identify and achieve consensus on research gaps. Participants included (1) subject matter experts, (2) professional society-designated leaders, (3) representatives from the federal government, and (4) representatives from private foundations. Before the conference, participants were provided a scoping review on layperson prehospital hemorrhage control. A 3-round modified Delphi consensus process was conducted to determine high-priority research questions. The top items, with median rating of 8 or more on a Likert scale of 1 to 9 points, were identified and became part of the national STB research agenda.Findings: Forty-five participants attended the conference. In round 1, participants submitted 487 research questions. After deduplication and sorting, 162 questions remained across 5 a priori-defined themes. Two subsequent rounds of rating generated consensus on 113 high-priority, 27 uncertain-priority, and 22 low-priority questions. The final prioritized research agenda included the top 24 questions, including 8 for epidemiology and effectiveness, 4 for materials, 9 for education, 2 for global health, and 1 for health policy.Conclusions and relevance: The National STB Research Consensus Conference identified and prioritized a national research agenda to support laypersons in reducing preventable deaths due to life-threatening hemorrhage. Investigators and funding agencies can use this agenda to guide their future work and funding priorities

Unravelling the Photocatalytic Behavior of All-Inorganic Mixed Halide Perovskites: The Role of Surface Chemical States

Within the most mesmerizing materials in the world of optoelectronics, mixed halide perovskites (MHPs) have been distinguished because of the tunability of their optoelectronic properties, balancing both the light-harvesting efficiency and the charge extraction into highly efficient solar devices. This feature has drawn the attention of analogous hot topics as photocatalysis for carrying out more efficiently the degradation of organic compounds. However, the photo-oxidation ability of perovskite depends not only on its excellent light-harvesting properties but also on the surface chemical environment provided during its synthesis. Accordingly, we studied the role of surface chemical states of MHP-based nanocrystals (NCs) synthesized by hot-injection (H-I) and anion-exchange (A-E) approaches on their photocatalytic (PC) activity for the oxidation of β-naphthol as a model system. We concluded that iodide vacancies are the main surface chemical states that facilitate the formation of superoxide ions, O2●–, which are responsible for the PC activity in A-E-MHP. Conversely, the PC performance of H-I-MHP is related to the appropriate balance between band gap and a highly oxidizing valence band. This work offers new insights on the surface properties of MHP related to their catalytic activity in photochemical applications