We discuss an analytic approach for modeling structure formation in sheets, filaments and knots. This is accomplished by combining models of triaxial collapse with the excursion set approach: sheets are defined as objects which have collapsed along only one axis, filaments have collapsed along two axes, and halos are objects in which triaxial collapse is complete. In the simplest version of thi...

We discuss an analytic approach for modeling structure formation in sheets, filaments and knots. This is accomplished by combining models of triaxial collapse with the excursion set approach: sheets are defined as objects which have collapsed along only one axis, filaments have collapsed along two axes, and halos are objects in which triaxial collapse is complete. In the simplest version of thi...

One of the most important problems discussed recently in structural engineering is the structural reliability analysis considering uncertainties. To have an efficient optimization process for designing a safe structure, firstly it is required to study the effects of uncertainties on the seismic performance of structure and then incorporate these effects on the optimization process. In this stud...

BACKGROUND The advent of endoscopic lung volume reduction (ELVR), especially relying on valve technology to achieve atelectasis, has aroused new interest in the assessment of collateral ventilation, which has been implicated in ELVR failures. We are reporting on the use of a catheter-based device that measures airway pressures and flows, and calculates airway resistance in vivo. OBJECTIVES To...

In this paper, the initiation and propagation of structural damage in a building due to the truck collision to one of its corner columns were investigated. For this purpose, a three-dimensional 4-story moment resisting steel frame with intermediate ductility was considered. The structure was designed using ETABS software under standard dead, live, and earthquake loads, and then impact loading w...

We study here the structure of singularity forming in gravitational collapse of spherically symmetric inhomogeneous dust. Such a collapse is described by the TolmanBondi-Lemâitre metric, which is a two-parameter family of solutions to Einstein equations, characterized by two free functions of the radial coordinate, namely the ‘mass function’ F (r) and the ‘energy function’ f(r). The main new re...

We study here the behaviour of non-spacelike geodesics in dust collapse models in order to understand the casual structure of the spacetime. The geodesic families coming out, when the singularity is naked, corresponding to different initial data are worked out and analyzed. We also bring out the similarity of the limiting behaviour for different types of geodesics in the limit of approach to th...

Introduction A pathological condition not infrequently observed in leaves of orange trees as yellow, translucent, sunken areas, has been called "mesophyll collapse" by FAWCETT (6). Neither bacteria nor fungi seem to initiate this disorder of the leaves, though they may invade the weakened and collapsed tissues secondarily. The disorder has therefore been regarded as a physiological disturbance ...

Under special conditions bacteria excrete an attractant and aggregate. The high density regions initially collapse into cylindrical structures, which subsequently destabilize and break up into spherical aggregates. This paper presents a theoretical description of the process, from the structure of the collapsing cylinder to the spacing of the final aggregates. We show that cylindrical collapse ...

Catastrophic and sudden collapses of ecosystems are sometimes preceded by early warning signals that potentially could be used to predict and prevent a forthcoming catastrophe. Universality of these early warning signals has been proposed, but no formal proof has been provided. Here, we show that in relatively simple ecological models the most commonly used early warning signals for a catastrop...