Poor air quality causes an estimated 2.6 to 4.4 million premature deaths per year1-3. Hazardous conditions form when meteorological components allow the accumulation of pollutants in the near-surface atmosphere4-8. Global warming-driven changes to atmospheric circulation and the hydrological cycle9-13 are expected to alter the meteorological components that control pollutant build-up and disper...

Depression is a prevalent mental illness in developed countries. In Western medicine, experimental and clinical investigations have demonstrated that depression is associated with the dysregulation of neurotransmitter signaling, and symptoms of depression can be alleviated by therapeutic intervention. However, patients taking antidepressant drugs often experience serious side effects and high r...

The shape of a bypass graft plays an important role on its efficacy. Here, we investigated flow through two vascular graft designs-with and without cuff at the anastomosis. We conducted Digital Particle Image Velocimetry (DPIV) measurements to obtain the flow field information through these vascular grafts. Two pulsatile flow waveforms corresponding to cardiac cycles during the rest and the exc...

This paper conducts experimental tests to study the stagnation behavior the Interacted Multiple Ant Colonies Optimization (IMACO) framework. The idea of different ant colonies use different types of problem dependent heuristics has been proposed as well. The performance of IMACO was demonstrated by comparing it with the Ant Colony System (ACS) the best performing ant algorithm. The computationa...

Restarting GMRES, a linear solver frequently used in numerical schemes, is known to suffer from stagnation. In this paper, a simple strategy is proposed to detect and avoid stagnation, without modifying the standard GMRES code. Numerical tests with the modified GMRES(m), GMRESH(m) procedure, alone and as part of an inexact Newton procedure with several choices for the forcing term, demonstrate ...

We extend Galor and Weil (2000) by including geographical factors in order to show that under some initial conditions, an economy may be locked in Malthusian stagnation and never take off. Specifically, we characterize the set of geographical factors for which this happens, and this way we show how the interplay of the available “land”, its suitability for living, and its degree of isolation, d...

This study examines a troubling phenomenon occurring recently in several Latin American economies: a marked slowdown in bank credit to the private sector. Based on the study of five countries (Argentina, Bolivia, Colombia, Peru, and Mexico), we first document the magnitude of the problem, asking how severe and prolonged has the slowdown been and how this behavior compare with the past? Second, ...

Axisymmetric jets impinging perpendicularly on a wall are encountered in a variety of real-life situations such as Chemical Vapor Deposition (CVD) processes (Goodwin, 2003). Although the fluid mechanics of the wall-impinging jets are interesting phenomena in their own right, this topic is studied here for two reasons. The first is to assess the extent to which experimental data and numerical da...

Empirical evidence questions fundamental concepts of the human population dynamics. One of the key conclusions of this study is that positive checks activate the efficient Malthusian regeneration mechanism, suggesting that the Epoch of Malthusian Stagnation, the first stage of growth claimed by the Demographic Transition Theory, did not exist.

This paper develops and uses a computation model to explore the transient ignition dynamics of catalytic combustion in a stagnation-flow configuration. The analysis considers the elementary heterogeneous chemistry associated with catalytic behavior at the surface. It also considers gas-dynamic effects in the boundary layer, including temporal and spatial pressure variations. The gas-dynamic eff...