Propagation of Epileptiform Events across the Corpus Callosum in a Cingulate Cortical Slice Preparation

We report on a novel mouse in vitro brain slice preparation that contains intact callosal axons connecting anterior cingulate cortices (ACC). Callosal connections are demonstrated by the ability to regularly record epileptiform events between hemispheres (bilateral events). That the correlation of these events depends on the callosum is demonstrated by the bisection of the callosum in vitro. Epileptiform events are evoked with four different methods: (1) bath application of bicuculline (a GABA-A antagonist); (2) bicuculline+MK801 (an NMDA receptor antagonist), (3) a zero magnesium extracellular solution (0Mg); (4) focal application of bicuculline to a single cortical hemisphere. Significant increases in the number of epileptiform events, as well as increases in the ratio of bilateral events to unilateral events, are observed during bath applications of bicuculline, but not during applications of bicuculline+MK-801. Long ictal-like events (defined as events >20 seconds) are only observed in 0Mg. Whole cell patch clamp recordings of single neurons reveal strong feedforward inhibition during focal epileptiform events in the contralateral hemisphere. Within the ACC, we find differences between the rostral areas of ACC vs. caudal ACC in terms of connectivity between hemispheres, with the caudal regions demonstrating shorter interhemispheric latencies. The morphologies of many patch clamped neurons show callosally-spanning axons, again demonstrating intact callosal circuits in this in vitro preparation

COMPUTERIZED DESIGN OF REINFORCED CONCRETE COLUMNS BY LOAD FACTOR METHOD.

The load factor method of design for reinforced concrete columns subjected to axial load and biaxial bending has been computerized to the extent that, given the concrete section and the applied loads of each loading case, the computer program evaluates the amount and distribution of reinforcement required together with the corresponding load factor of each loading case. The formulation and the procedure developed are applicable to columns of arbitrary cross-section, with or without voids. The design process is basically an iterative process of gradually increasing the amount of reinforcement till the required load factor is achieved.link_to_subscribed_fulltex

Computerized ultimate strength analysis of reinforced concrete sections subjected to axial compression and biaxial bending

This article presents a method of evaluating the ultimate strength capacities of reinforced concrete sections of arbitrary shapes and with or without voids subjected to axial compression and biaxial bending. The concept of load fraction is introduced so as to provide a quantitative measure of structural adequacy. An iterative procedure to determine the load fractions is proposed. Necessary integration over arbitrary domains is dealt with by boundary integration method. This procedure can be computerized readily to high automation. A wide range of reinforced concrete sections are analysed, as examples, using a desk-top computer. © 1985.link_to_subscribed_fulltex

PLASTIC DESIGN OF INFILLED FRAMES.

This paper introduces a method of plastic design for both non-integral and integral infilled frames. It begins with a brief summary of the non-linear behavior of infilled frames, on the basis of which a unified plastic theory is proposed for both non-integral and integral infilled frames, taking into account the formation of plastic hinges in the frame, cracking and crushing of the infilled panel, and shearing of the interface connection. A simplified method of design is introduced and design charts are prepared for rapid computation. Examples are given to illustrate the use of these charts.link_to_subscribed_fulltex

COMPUTER AIDED DESIGN OF REINFORCED CONCRETE MEMBERS SUBJECTED TO AXIAL COMPRESSION AND BIAXIAL BENDING.

A rapid method for assessing the ultimate strength of reinforced concrete members subjected to axial compression and biaxial bending is presented. The design procedure is computerized to full automation for arbitrary cross-sections, with or without voids. The concept of load fraction, which is the fraction of the applied load that can be adequately withstood, is introduced for quantitative measure of structural adequacy. The load fraction also provides useful guidelines to necessary redesign. An iterative procedure is evolved for making adequate provision for ultimate strength by gradually increasing the amount of reinforcement till the required load fraction is achieved. Reinforcement is always added at locations having the highest increase of load fraction/unit area of added reinforcement. Practical considerations in symmetry, nominal reinforcement, and steel congestion, etc. , are taken into account.link_to_subscribed_fulltex

PLASTIC THEORY OF NON-INTEGRAL INFILLED FRAMES.

A plastic theory of non-integral infilled frames is proposed. In the theory, the stress redistribution towards collapse is taken into account and friction is neglected for strength reserve. Applications to both single-story and multistory structures are studied. Simple design rules are proposed in the case of multistory frames so that they can be designed story by story.link_to_subscribed_fulltex

Nonlinear analysis of integral infilled frames

The nonlinear behaviour of integral infilled frames, in which the infill and the frame are bonded or connected together, is studied both experimentally and analytically. In the theoretical study, a finite-element method is used and the nonlinearities of the materials and the structural interface are taken into account. The entire range of load-deflection behaviour is investigated. Besides stiffness and strength, the stress distribution, crack patterns and collapse modes are also studied. Particular attention is directed towards the stress redistribution before collapse. The effects of the connectors are investigated in relation to the stiffness and strength of the infilled frames. Theoretical stiffness and strength predictions are compared with experimental results. © 1984.link_to_subscribed_fulltex