Sustainable Air Traffic Management System Development Methodology

As it is defined in ATM 2000+ Strategy (Eurocontrol 2001), the mission of the Air Traffic Management (ATM) System is: “For all the phases of a flight, the ATM system should facilitate a safe, efficient, and expedite traffic flow, through the provision of adaptable ATM services that can be dimensioned in relation to the requirements of all the users and areas of the European air space. The ATM services should comply with the demand, be compatible, operate under uniform principles, respect the environment and satisfy the national security requirements.” The objective of this paper is to present a methodology designed to evaluate the status of the ATM system in terms of the relationship between the offered capacity and traffic demand, identifying weakness areas and proposing solutions. The first part of the methodology relates to the characterization and evaluation of the current system, while a second part proposes an approach to analyze the possible development limit. As part of the work, general criteria are established to define the framework in which the analysis and diagnostic methodology presented is placed. They are: the use of Air Traffic Control (ATC) sectors as analysis unit, the presence of network effects, the tactical focus, the relative character of the analysis, objectivity and a high level assessment that allows assumptions on the human and Communications, Navigation and Surveillance (CNS) elements, considered as the typical high density air traffic resources. The steps followed by the methodology start with the definition of indicators and metrics, like the nominal criticality or the nominal efficiency of a sector; scenario characterization where the necessary data is collected; network effects analysis to study the relations among the constitutive elements of the ATC system; diagnostic by means of the “System Status Diagram”; analytical study of the ATC system development limit; and finally, formulation of conclusions and proposal for improvement. This methodology was employed by Aena (Spanish Airports Manager and Air Navigation Service Provider) and INECO (Spanish Transport Engineering Company) in the analysis of the Spanish ATM System in the frame of the Spanish airspace capacity sustainability program, although it could be applied elsewhere.

Responses to increasing exercise upon reaching the anaerobic threshold, and their control by the central nervous system

Sistema nervioso y ejercicio

Influencia del ejercicio físico desarrollado durante el embarazo en la respuesta cardiaca fetal = Influence of a physical activity program performed during pregnancy on fetal heart response

INTRODUCCIÓN: El riesgo de padecer enfermedades cardiovasculares y los índices de obesidad infantil han ido en aumento durante los últimos años empobreciendo la salud de la población. La Teoría de Barker relaciona el estado de salud de la madre con el desarrollo fetal, asociando a un deficiente estado físico y hábitos de vida negativos de la mujer embarazada con el aumento del riesgo de padecer cardiopatías en la infancia y adolescencia, así como predisponer al recién nacido a padecer sobrepeso y/u obesidad en su vida posterior. Por otro lado los estudios efectuados sobre ejercicio físico durante el embarazo reportan beneficios para salud materna y fetal. Uno de los parámetros más utilizados para comprobar la salud fetal es su frecuencia cardiaca, mediante la que se comprueba el buen desarrollo del sistema nervioso autónomo. Si se observa este parámetro en presencia de ejercicio materno podría encontrarse una respuesta crónica del corazón fetal al ejercicio materno como consecuencia de una adaptación y mejora en el funcionamiento del sistema nervioso autónomo del feto. De esta forma podría mejorar su salud cardiovascular intrauterina, lo que podría mantenerse en su vida posterior descendiendo el riesgo de padecer enfermedades cardiovasculares en la edad adulta. OBJETIVOS: Conocer la influencia de un programa de ejercicio físico supervisado en la frecuencia cardiaca fetal (FCF) en reposo y después del ejercicio materno en relación con gestantes sedentarias mediante la realización de un protocolo específico. Conocer la influencia de un programa de ejercicio físico en el desarrollo del sistema nervioso autónomo fetal, relacionado con el tiempo de recuperación de la FCF. MATERIAL Y MÉTODO: Se diseñó un ensayo clínico aleatorizado multicéntrico en el que participaron 81 gestantes (GC=38, GE=43). El estudio fue aprobado por el comité ético de los hospitales que participaron en el estudio. Todas las gestantes fueron informadas y firmaron un consentimiento para su participación en el estudio. Las participantes del GE recibieron una intervención basada en un programa de ejercicio físico desarrollado durante la gestación (12-36 semanas de gestación) con una frecuencia de tres veces por semana. Todas las gestantes realizaron un protocolo de medida de la FCF entre las semanas 34-36 de gestación. Dicho protocolo consistía en dos test llevados a cabo caminando a diferentes intensidades (40% y 60% de la frecuencia cardiaca de reserva). De este protocolo se obtuvieron las principales variables de estudio: FCF en reposo, FCF posejercicio al 40 y al 60% de intensidad, tiempo de recuperación de la frecuencia cardiaca fetal en ambos esfuerzos. El material utilizado para la realización del protocolo fue un monitor de frecuencia cardiaca para controlar la frecuencia cardiaca de la gestante y un monitor fetal inalámbrico (telemetría fetal) para registrar el latido fetal durante todo el protocolo. RESULTADOS: No se encontraron diferencias estadísticamente significativas en la FCF en reposo entre grupos (GE=140,88 lat/min vs GC= 141,95 lat/min; p>,05). Se encontraron diferencias estadísticamente significativas en el tiempo de recuperación de la FCF entre los fetos de ambos grupos (GE=135,65 s vs GC=426,11 s esfuerzo al 40%; p<,001); (GE=180,26 s vs GC=565,61 s esfuerzo al 60%; p<,001). Se encontraron diferencias estadísticamente significativas en la FCF posejercicio al 40% (GE=139,93 lat/min vs GC=147,87 lat/min; p<,01). No se encontraron diferencias estadísticamente significativas en la FCF posejercicio al 60% (GE=143,74 lat/min vs GC=148,08 lat/min; p>,05). CONLUSIÓN: El programa de ejercicio físico desarrollado durante la gestación influyó sobre el corazón fetal de los fetos de las gestantes del GE en relación con el tiempo de recuperación de la FCF. Los resultados muestran un posible mejor funcionamiento del sistema nervioso autónomo en fetos de gestantes activas durante el embarazo. ABSTRACT INTRODUCTION: The risk to suffer cardiovascular diseases and childhood obesity index has grown in the last years worsening the health around the population. Barker´s Theory related maternal health with fetal development establishing an association between a poorly physical state and an unhealthy lifestyle in the pregnant woman with the risk to suffer heart disease during childhood and adolescence, childhood overweight and/or obese is related to maternal lifestyle. By the other way researches carried out about physical exercise and pregnancy show benefits in maternal and fetal health. One of the most studied parameters to check fetal health is its heart rate, correct fetal autonomic nervous system development and work is also corroborated by fetal heart rate. Looking at this parameter during maternal exercise a chronic response of fetal heart could be found due to an adaptation and improvement in the working of the autonomic nervous system. Therefore its cardiovascular health could be enhanced during its intrauterine life and maybe it could be maintained in its posterior life descending the risk to suffer cardiovascular diseases in adult life. OBJECTIVES: To know the influence of a supervised physical activity program in the fetal heart rate (FHR) at rest, FHR after maternal exercise related to sedentary pregnant women by a FHR assessment protocol. To know the influence of a physical activity program in the development of the autonomic nervous system related to FHR recovery time. MATERIAL AND METHOD: A multicentric randomized clinical trial was design in which 81 pregnant women participated (CG=38, EG=43). The study was approved by the ethics committee of all of the hospitals participating in the study. All of the participants signed an informed consent for their participation in the study. EG participants received an intervention based on a physical activity program carried out during gestation (12-36 gestation weeks) with a three days a week frequency. All of the participants were tested between 34-36 weeks of gestation by a specific FHR assessment protocol. The mentioned protocol consisted in two test performed walking and at a two different intensities (40% and 60% of the reserve heart rate). From this protocol we obtained the main research variables: FHR at rest, FHR post-exercise at 40% and 60% intensity, and FHR recovery time at both walking test. The material used to perform the protocol were a FH monitor to check maternal HR and a wireless fetal monitor (Telemetry) to register fetal beats during the whole protocol. RESULTS: There were no statistical differences in FHR at rest between groups (EG=140,88 beats/min vs CG= 141,95 beats/min; p>,05). There were statistical differences in FHR recovery time in both walking tests between groups (EG=135,65 s vs CG=426,11 s test at 40% intensity; p<,001); (EG=180,26 s vs CG=565,61 s test at 60% intensity; p<,001). Statistical differences were found in FHR post-exercise at 40% intensity between groups (EG=139,93 beats/min vs CG=147,87 beats/min; p<,01). No statistical differences were found in FHR at rest post-exercise at 60% intensity between groups (EG=143,74 beats/min vs CG=148,08 beats/min; p>,05). CONCLUSIONS: The physical activity program performed during gestation had an influence in fetal heart of the fetus from mother in the EG related to FHR recovery time. These results show a possible enhancement on autonomic nervous system working in fetus from active mothers during gestation.

A model of the spatially dependent mechanical properties of the axon during its growth

Neuronal growth is a complex process involving many intra- and extracellular mechanisms which are collaborating conjointly to participate to the development of the nervous system. More particularly, the early neocortical development involves the creation of a multilayered structure constituted by neuronal growth (driven by axonal or dendritic guidance cues) as well as cell migration. The underlying mechanisms of such structural lamination not only implies important biochemical changes at the intracellular level through axonal microtubule (de)polymerization and growth cone advance, but also through the directly dependent stress/stretch coupling mechanisms driving them. Efforts have recently focused on modeling approaches aimed at accounting for the effect of mechanical tension or compression on the axonal growth and subsequent soma migration. However, the reciprocal influence of the biochemical structural evolution on the mechanical properties has been mostly disregarded. We thus propose a new model aimed at providing the spatially dependent mechanical properties of the axon during its growth. Our in-house finite difference solver Neurite is used to describe the guanosine triphosphate (GTP) transport through the axon, its dephosphorylation in guanosine diphosphate (GDP), and thus the microtubules polymerization. The model is calibrated against experimental results and the tensile and bending mechanical stiffnesses are ultimately inferred from the spatially dependent microtubule occupancy. Such additional information is believed to be of drastic relevance in the growth cone vicinity, where biomechanical mechanisms are driving axonal growth and pathfinding. More specifically, the confirmation of a lower stiffness in the distal axon ultimately participates in explaining the controversy associated to the tensile role of the growth cone.