Papers by Leonardo Fabio Martinez Avila
In the last years the design of seismic resistant masonry buildings has used mainly experimental ... more In the last years the design of seismic resistant masonry buildings has used mainly experimental approaches for the evaluation and assessment of the seismic response of these structures. In the literature is possible to find an important amount of related research. It is found that due to cost, feasibility and good agreement with real cases most of the experimental tests have been performed on masonry elements, for instance, individual walls by means of cyclic tests assuming the in-plane failure mode as the governing behaviour. The Present work aims to evaluate the seismic behaviour of masonry buildings implemented a new construction system by means of dynamic testing on entire buildings using shaking table, attained more accurate results in
European Respiratory Journal, Sep 1, 2012
Universitas Humanistica, Jan 6, 2006
Universitas Humanistica, 2006
Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto
Ante la insuficiencia de conocimiento sistematizado sobre la operacion de Programas de Transferen... more Ante la insuficiencia de conocimiento sistematizado sobre la operacion de Programas de Transferencia Condicionada (PTC) con poblaciones indigenas en America Latina y el Caribe (ALC), el Banco Interamericano de desarrollo (BID) y el Banco Mundial (BM) han decidido apoyar el intercambio de conocimientos y experiencias entre los diferentes paises que han hecho adelantos en este sentido. El objetivo es aportar elementos teoricos, metodologicos y operativos para adecuar el funcionamiento de estos programas a las caracteristicas propias de la poblacion indigena, de manera que se entregue un servicio con pertinencia cultural y mayor impacto en el bienestar de familias de esta poblacion, segun sus propias concepciones de desarrollo. Como un primer paso en este sentido, el presente documento ofrece un marco conceptual preliminar para la realizacion de estudios de caso.
A new construction system for masonry buildings is analysed. Identification of modal parameters h... more A new construction system for masonry buildings is analysed. Identification of modal parameters has been carried out in two structural solutions by using this system namely reinforced and unreinforced symmetric two-story concrete block masonry buildings. Experimental shaking table tests were developed on these buildings by incremental inputs. Traditional modal analysis by using low amplitude input motion was made before and after dynamic tests and stiffness degradation has been correlated. Mode shapes, mode frequencies, damping ratios and damage identification through the test are discussed
ABSTRACT In maintenance management, decision making assumes a very important dimension. Maintenan... more ABSTRACT In maintenance management, decision making assumes a very important dimension. Maintenance systems are commonly feeded with large amounts of data that are quickly processed and almost exists total dependence of historical references and of the ...
The evolution of structural masonry is briefly reviewed, from old thrust line behavior to modern ... more The evolution of structural masonry is briefly reviewed, from old thrust line behavior to modern global behavior using shear walls. For modern structural masonry, the use of unreinforced, confined and reinforced masonry is addressed in seismic areas. A first focus is given to recent approaches towards the safety assessment of unreinforced masonry buildings and their performance in shaking table tests. Subsequently, building systems for modern masonry structures recently developed and tested at University of Minho are presented, one based on lightweight concrete blocks and another based on normal concrete blocks. The experimental and numerical work carried out is discussed and conclusions on the performance of the systems are given.
Background : The deleterious effects of atmospheric pollution on human health are also known by i... more Background : The deleterious effects of atmospheric pollution on human health are also known by increasing incidence and exacerbations of pre-existing lung diseases such as asthma. However, the effects of diesel exhausted particles (DEP) on acute allergic pulmonary inflammation during asthma sensitization process remain unclear. Objective : To evaluate the effects of 5 weeks of DEP exposure during the sensitization process of acute allergic pulmonary inflammation in an experimental murine model. Methods : Male Swiss mice were divided into 4 groups: non OVA-sensitized and saline instillation animals (10 µL/mouse) (Control, n=6), non OVA-sensitized and DEP instillation mice (3 mg/mL-10 µL/mouse) (DEP, n=8), OVA-sensitized and saline instillation animals (OVA, n=6) and OVA-sensitized and DEP instillation mice (DEP+OVA, n=8). 24 hours after OVA or saline aerosol challenge anesthetized mice were euthanized and was performed measures of inflammatory cells from bronchoalveolar fluid (BALF) and IL-4, IL-5, IL-1β, TNF-α and total immunoglobulin IgE levels from lung tissue by enzyme-linked immunosorbent assay. Results : The coexposure to DEP resulted in an increase of eosinophils, neutrophils and lymphocytes in BALF (p Conclusion : In this experimental model, the effects of 5 weeks of DEP exposure on sensitization process resulted in an increase of leucocytes in BALF and cytokines levels in OVA group, suggesting that DEP exposure has an additional effect on lung inflammation in asthma.
Bulletin of Earthquake Engineering, 2012
ABSTRACT Masonry buildings worldwide exhibited severe damage and collapse in recent strong earthq... more ABSTRACT Masonry buildings worldwide exhibited severe damage and collapse in recent strong earthquake events. It is known that their brittle behavior, which is mainly due to the combination of low tensile strength, large mass and insufficient connection between structural elements, is the main limitation for their structural implementation in residential buildings. A new construction system for masonry buildings using concrete blocks units and trussed reinforcement is presented here and its seismic behavior is validated through shaking table tests. Dynamic tests of two geometrically identical two-story reduced scale (1:2) models have been carried out, considering artificial accelerograms compatible with the elastic response spectrum defined by the Eurocode 8. The first model was reinforced with the new proposed system while the second model was built with unreinforced masonry. The experimental analysis encompasses local and global parameters such as cracking patterns, failure mechanisms, and in-plane and out-of-plane behavior in terms of displacements and lateral drifts from where the global dynamic behavior of the two buildings is analyzed comparatively. Finally, behavior factors for the design recommendations in case of unreinforced masonry are also evaluated.
The combination of a series of structural and economic advantages like the high capacity to resis... more The combination of a series of structural and economic advantages like the high capacity to resist compressive loads, the simple and easy method of construction, comfort properties and structural performance given for the new masonry structures makes the implementation of masonry as a profitable solution for the increased residential houses demand. An innovative solution for the construction of low to medium residential masonry buildings is here analysed. The assessment of the earthquake resistance capacity of this system is evaluated aiming at providing further guidelines for its design and construction. This paper presents a step in this process related to the experimental mechanical validation of the constructive system based on concrete block masonry buildings under seismic loading.
World Neurosurgery, 2021
OBJECTIVE Brainstem safe entry zones (EZ) are gates to access the intrinsic pathology of the brai... more OBJECTIVE Brainstem safe entry zones (EZ) are gates to access the intrinsic pathology of the brainstem. We performed a quantitative analysis of the intrinsic surgical corridor limits of the most commonly used EZs and illustrated these through an inside perspective using 2D and 3D photographs as well as interactive 3D model reconstructions. METHODS Twenty-six human brainstems (52 sides) with attached cerebellums were prepared using Klingler´s method and dissected. The safe working areas and distances for each EZ were defined according to eloquent fiber tracts and nuclei. RESULTS The largest safe distance corresponded to the depth for the lateral mesencephalic sulcus(4.8mm), supratrigeminal(10mm), epitrigeminal(13.2mm), peritrigeminal(13.3mm), lateral transpeduncular(22.3mm), and infracollicular(4.6mm). To the rostrocaudal axis for the perioculomotor(11.7mm), suprafacial(12.6mm), and transolivar(12.8mm). And, to the mediolateral axis for the supracollicular(9.1mm), and infracollicular(7mm). The safe working areas were 46.7mm2 for the perioculomotor, 21.3mm2 for the supracollicular, 14.8mm2 for the infracollicular, 33.1mm2 for the supratrigeminal, 34.3mm2 for the suprafacial, 21.9mm2 for the infrafacial, and 51.7mm2 for the transolivar. CONCLUSIONS The largest safe distance in most EZs corresponded to the depth, followed by the rostrocaudal axis and finally to the mediolateral axis. The transolivar had the largest safe working area of all EZs. The supracollicular had the largest safe area to access the midbrain tectum, and the suprafacial for the floor of the fourth ventricle.
World Neurosurgery, 2020
Postoperative coronal T2-weighted image. (B) Sagittal T1-weighted image. (C) Sagittal T2-weighted... more Postoperative coronal T2-weighted image. (B) Sagittal T1-weighted image. (C) Sagittal T2-weighted image. (D) Axial postgadolinium T1-weighted image.
Journal of Instrumentation, 2010
The CMS Collaboration conducted a month-long data-taking exercise known as the Cosmic Run At Four... more The CMS Collaboration conducted a month-long data-taking exercise known as the Cosmic Run At Four Tesla in late 2008 in order to complete the commissioning of the experiment for extended operation. The operational lessons resulting from this exercise were addressed in the subsequent shutdown to better prepare CMS for LHC beams in 2009. The cosmic data collected have been invaluable to study the performance of the detectors, to commission the alignment and calibration techniques, and to make several cosmic ray measurements. The experimental setup, conditions, and principal achievements from this data-taking exercise are described along with a review of the preceding integration activities.
El conocimiento sistematizado sobre Programas de Transferencias Condicionadas (PTC) a poblaciones... more El conocimiento sistematizado sobre Programas de Transferencias Condicionadas (PTC) a poblaciones indigenas en America Latina es aun insuficiente. La especificidad de esta poblacion se manifiesta principalmente en el nivel de organizacion sociopolitica y control territorial que, por lo general, no tienen otros tipos de poblacion beneficiaria de estos Programas. Familias en Accion (FeA) es el primer Programa de Transferencias Condicionadas en America Latina que desarrollo un esquema de operacion disenado especificamente para poblaciones indigenas, modificando los procesos de focalizacion y seleccion de las familias beneficiarias, concertacion de arreglos institucionales para la operacion del Programa a nivel local y las "acciones complementarias" de fortalecimiento institucional y promocion de la educacion y la salud. Esta Nota tecnica captura las lecciones aprendidas de este proceso.
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Papers by Leonardo Fabio Martinez Avila