Seismic Evaluation of Low Rise RC Framed Building Designed According to Venezuelan Codes

Along its history, Venezuela has been severely affected by destructive earthquakes. Approximately 80% of the population lives in seismically active areas, where have occurred destructive earthquakes even in recent times; The seismic hazard, inadequate design and construction of buildings as well as the damage occurred from previous earthquakes, demonstrate a high vulnerability in existing buildings. Then it is essential to continuously make progress and research in the field of earthquake engineering and upgrade the seismic design codes. Seismic upgrade requires the evaluation or predictions of the expected damage to structures at the time of an earthquake of a certain severity occur. From this prediction it can be defined solutions for the reduction of structural vulnerability.Postprint (published version

Chapter 11 Análisis numérico de la reparación y refuerzo de estructuras con FRP

This chapter presents a procedure to assess the magnitude of the damage local and global damage in structures subjected to static and dynamic actions, with special emphasis on the seismic problem. In addition to the formulation for the evaluation of the damage, introduces the concept of structural reinforcement and repair by composite laminates of epoxy matrix with carbon fiber reinforcement. For this purpose, the use of the theory of mixtures to compose a composite material from their basic components. Damage is also assessed in these reinforced and / or repaired structures and the influence of these improvements on the assessment of the overall damage of the structure is discussed.En este capítulo se presenta un procedimiento para evaluar la magnitud del daño local y el daño global en estructuras sometidas a acciones estáticas y dinámicas, con especial énfasis en el problema sísmico. Además de la formulación para la evaluación del daño, se introduce el concepto de refuerzo y reparación estructural mediante laminados compuestos de matriz epóxica con refuerzo de fibras de carbono. Para esta finalidad, se menciona la utilización de la teoría de mezclas para componer un material compuesto a partir de sus componentes básicas. También se evalúa el daño en estas estructuras reforzadas y/o reparadas y se comenta la influencia de estas mejoras en la valoración del daño global de la estructura

Análisis numérico de la reparación y refuerzo de estructuras con FRP

En este capítulo se presenta un procedimiento para evaluar la magnitud del daño local y el daño global en estructuras sometidas a acciones estáticas y dinámicas, con especial énfasis en el problema sísmico. Además de la formulación para la evaluación del daño, se introduce el concepto de refuerzo y reparación estructural mediante laminados compuestos de matriz epóxica con refuerzo de fibras de carbono. Para esta finalidad, se menciona la utilización de la teoría de mezclas para componer un material compuesto a partir de sus componentes básicas. También se evalúa el daño en estas estructuras reforzadas y/o reparadas y se comenta la influencia de estas mejoras en la valoración del daño global de la estructura.Fil: Oller, Sergio Horacio Cristobal. Universidad Politécnica de Catalunya; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Molina, Maritzabel. Universidad Nacional de Colombia; ColombiaFil: Vielma, Juan Carlos. Universidad Centroccidental Lisandro Alvarado; VenezuelaFil: Martínez, Xavier. Universidad Politécnica de Catalunya; EspañaFil: Barbat, Alex H.. Universidad Politécnica de Catalunya; EspañaFil: Nallim, Liz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentin

Acetylcholine induces GABA release onto rod bipolar cells through heteromeric nicotinic receptors expressed in A17 amacrine cells.

Abstract Acetylcholine (ACh) is a major retinal neurotransmitter that modulates visual processing through a large repertoire of cholinergic receptors expressed on different retinal cell types. ACh is released from starburst amacrine cells under scotopic conditions, but its effects on cells of the rod pathway have not been investigated. Using whole-cell patch clamp recordings in slices of rat retina, we found that ACh application triggers GABA release onto rod bipolar (RB) cells. GABA was released from A17 amacrine cells and activated postsynaptic GABAA and GABAC receptors in RB cells. The sensitivity of ACh-induced currents to nicotinic ACh receptor (nAChR) antagonists (TMPH ~ mecamylamine > erysodine > DhβE > MLA) together with the differential potency of specific agonists to mimic ACh responses (cytisine >> RJR2403 ~ choline), suggest that A17 cells express heteromeric nAChRs containing the β4 subunit. Activation of nAChRs induced GABA release after Ca2+ accumulation in A17 cell dendrites and varicosities mediated by L-type voltage-gated calcium channels (VGCCs) and intracellular Ca2+ stores. Inhibition of acetyl-cholinesterase depolarized A17 cells and increased spontaneous inhibitory postsynaptic currents in RB cells, indicating that endogenous ACh enhances GABAergic inhibition of RB cells. Moreover, injection of neostigmine or cytisine reduced the b-wave of the scotopic flash electroretinogram, suggesting that cholinergic modulation of GABA release controls RB cell activity in vivo. These results describe a novel regulatory mechanism of RB cell inhibition and complement our understanding of the neuromodulatory control of retinal signal processing

Electrical coupling between A17 cells enhances reciprocal inhibitory feedback to rod bipolar cells

A17 amacrine cells are an important part of the scotopic pathway. Their synaptic varicosities receive glutamatergic inputs from rod bipolar cells (RBC) and release GABA onto the same RBC terminal, forming a reciprocal feedback that shapes RBC depolarization. Here, using patch-clamp recordings, we characterized electrical coupling between A17 cells of the rat retina and report the presence of strongly interconnected and non-coupled A17 cells. In coupled A17 cells, evoked currents preferentially flow out of the cell through GJs and cross-synchronization of presynaptic signals in a pair of A17 cells is correlated to their coupling degree. Moreover, we demonstrate that stimulation of one A17 cell can induce electrical and calcium transients in neighboring A17 cells, thus confirming a functional flow of information through electrical synapses in the A17 coupled network. Finally, blocking GJs caused a strong decrease in the amplitude of the inhibitory feedback onto RBCs. We therefore propose that electrical coupling between A17 cells enhances feedback onto RBCs by synchronizing and facilitating GABA release from inhibitory varicosities surrounding each RBC axon terminal. GJs between A17 cells are therefore critical in shaping the visual flow through the scotopic pathway.This study was supported by CINV, a Millennium Institute (P09-022-F) funded by the Millenium Scientific Initiative of the Ministry of Economy, Development and Tourism (Chile), a graduate MECESUP fellowship and a CONYCIT PhD support grant to CE and a FONDECYT No. 1171228 and 1150638.Peer reviewe

Nitric oxide modulates the temporal properties of the glutamate response in type 4 OFF bipolar cells.

Nitric oxide (NO) is involved in retinal signal processing, but its cellular actions are only partly understood. An established source of retinal NO are NOACs, a group of nNOS-expressing amacrine cells which signal onto bipolar, other amacrine and ganglion cells in the inner plexiform layer. Here, we report that NO regulates glutamate responses in morphologically and electrophysiologically identified type 4 OFF cone bipolar cells through activation of the soluble guanylyl cyclase-cGMP-PKG pathway. The glutamate response of these cells consists of two components, a fast phasic current sensitive to kainate receptor agonists, and a secondary component with slow kinetics, inhibited by AMPA receptor antagonists. NO shortened the duration of the AMPA receptor-dependent component of the glutamate response, while the kainate receptor-dependent component remained unchanged. Application of 8-Br-cGMP mimicked this effect, while inhibition of soluble guanylate cyclase or protein kinase G prevented it, supporting a mechanism involving a cGMP signaling pathway. Notably, perfusion with a NOS-inhibitor prolonged the duration of the glutamate response, while the NO precursor L-arginine shortened it, in agreement with a modulation by endogenous NO. Furthermore, NO accelerated the response recovery during repeated stimulation of type 4 cone bipolar cells, suggesting that the temporal response properties of this OFF bipolar cell type are regulated by NO. These results reveal a novel cellular mechanism of NO signaling in the retina, and represent the first functional evidence of NO modulating OFF cone bipolar cells

Publisher Correction: Electrical coupling between A17 cells enhances reciprocal inhibitory feedback to rod bipolar cells

Correction to: Scientific Reports https://doi.org/10.1038/s41598-018-21119-0, published online 15 February 2018.Peer reviewe

Chapter 11 Análisis numérico de la reparación y refuerzo de estructuras con FRP

This chapter presents a procedure to assess the magnitude of the damage local and global damage in structures subjected to static and dynamic actions, with special emphasis on the seismic problem. In addition to the formulation for the evaluation of the damage, introduces the concept of structural reinforcement and repair by composite laminates of epoxy matrix with carbon fiber reinforcement. For this purpose, the use of the theory of mixtures to compose a composite material from their basic components. Damage is also assessed in these reinforced and / or repaired structures and the influence of these improvements on the assessment of the overall damage of the structure is discussed

Non-canonical type 1 cannabinoid receptor signaling regulates night visual processing in the inner rat retina

Summary: Type 1 cannabinoid receptors (CB1Rs) are expressed in major retinal neurons within the rod-pathway suggesting a role in regulating night visual processing, but the underlying mechanisms remain poorly understood. Using acute rat retinal slices, we show that CB1R activation reduces glutamate release from rod bipolar cell (RBC) axon terminals onto AII and A17 amacrine cells through a pathway that requires exchange proteins directly activated by cAMP (EPAC1/2) signaling. Consequently, CB1R activation abrogates reciprocal GABAergic feedback inhibition from A17 amacrine cells. Moreover, the activation of CB1Rs in vivo enhances and prolongs the time course of the dim-light rod-driven visual responses, an effect that was eliminated when both GABAA and GABAC receptors were blocked. Altogether, our findings underscore a non-canonical mechanism by which cannabinoid signaling regulates RBC dyad synapses in the inner retina to regulate dim-light visual responses to fine-tune night vision