Temporal dynamics of a two-neuron continuous network model with time delay

AbstractIn this paper we consider a simple analog neural network model consisting of two continuous nonlinear neurons with delay in signal transmission under appropriate restrictions on internal parameters. We derive conditions for the existence of single steady-state conditions for asymptotic stability, stability switches about the steady state, and bifurcation of the linearized system

Limit cycles in a prey-predator system

AbstractWe consider a generalised Gause-type prey-predator system, where both the prey and the predator species have independent 8specific growth rate. We proved that the system has limit cycles globally

Optimal portfolio choice under loss aversion

Prospect theory and loss aversion play a dominant role in behavioral finance. In this paper we derive closed-form solutions for optimal portfolio choice under loss aversion. When confronted with gains a loss averse investor behaves similar to a portfolio insurer. When confronted with losses, the investor aims at maximizing the probability that terminal wealth exceeds his aspiration level. Our analysis indicates that a representative agent model with loss aversion cannot resolve the equity premium puzzle. We also extend the martingale methodology to allow for more general utility functions and provide a simple approach to incorporate skewed and fat-tailed return distributions

Retirement saving with contribution payments and labor income as a benchmark for investments.

In this paper we study the retirement saving problem from the point of view of a plan sponsor, who makes contribution payments for the future retirement of an employee. The plan sponsor considers the employee's labor income as investment-benchmark in order to ensure the continuation of consumption habits after retirement. We demonstrate that the demand for risky assets increases at low wealth levels due to the contribution payments. We quantify the demand for hedging against changes in wage growth and find that it is relatively small. We show that downside-risk measures increase risk-taking at both low and high levels of wealth

Investing in a real world with mean-reverting inflation.

People are concerned about maintaining purchasing power in times of rising inflation. We formulate investment objectives in terms of real wealth, assuming investors derive utility from the number of goods they can buy with their monetary wealth. We derive closed-form solutions for the portfolio choice problem of constant relative risk averse investors, under the assumption that inflation rates are mean-reverting. We consider alternative specifications for the inflation compensation offered by the available assets, in order to study the effect on portfolio choice and welfare. Moreover, we study the added value of inflation-indexed bonds for the investor in our real framework

From boom til bust: how loss aversion affects asset prices

In 1996 Alan Greenspan warned that stock prices were "unduly escalated" and reflected "irrational exuberance". In this paper we describe an economy that can support a prolonged surge of asset prices, accompanied by a sharp increase of volatility. We study an equilibrium model where some agents are risk averse while others have loss averse preferences over wealth, according to prospect theory. We derive closed-form solutions for the equilibrium prices. In good states of the world, the loss averse investors with wealth above the threshold are momentum traders, thereby pushing prices far above the level in the benchmark economy. In moderately bad states of the world, the loss averse investors are contrarian, and equilibrium prices are kept relatively high and stable. Finally in extremely bad states, the loss averse investors are forced to retreat from the stock market in order to avoid bankruptcy, resulting in a sharp price drop

Dynamic asset allocation and downside-risk aversion

This paper considers dynamic asset allocation in a mean versus downside-risk framework. We derive closed-form solutions for the optimal portfolio weights when returns are lognormally distributed. Moreover, we study the impact of skewed and fat-tailed return distributions. We find that the optimal fraction invested in stocks is V-shaped: at low and high levels of wealth the investor increases the stock weight. The optimal strategy also exhibits reverse time-effects: the investor allocates more to stocks as the horizon approaches. Furthermore, the investment strategy becomes more risky for negatively skewed and fat-tailed return distributions

Strengthening of heat damaged reinforced concrete cylinders

The purpose of this study is to investigate the effectiveness of various strengthening techniques in restoring heat damaged reinforced concrete. A series of 40 reinforced concrete cylinders were tested under concentric compression after being jacketed externally with high strength fiber reinforced concrete (HSFRC), Ferrocement (FC) and Glass fiber reinforced polymer (GFRP) jackets. Concrete specimens were exposed to elevated temperatures ranging from room temperature to 900 ºC. The overall response of strengthened specimens was investigated vis-à-vis un-strengthened specimens in terms of axial compression, axial displacement and axial stress strain behaviour. The results indicate that important gains in strength and ductility can be achieved by strengthening heat – damaged R.C cylinders by HSFRC, FC and GFRP external Jacketing. GFRP jacketing was found to be the most effective method of strengthening fire or heat damaged concrete structures

CFR: A Finite Volume Approach for Computing Incompressible Viscous Flow

An incompressible unsteady viscous two-dimensional Navier-Stokes solver is developed by using “Consistent Flux Reconstruction” method. In this solver, the full Navier-Stokes equations have been solved numerically using a collocated finite volume scheme. In the present investigation, numerical simulations have been carried out for unconfined flow past a single circular cylinder with both structured and unstructured grids. In structured grid, quadrilateral cells are used whereas triangular elements are used in unstructured grid. Simulations are performed at Reynolds number (Re) = 100 and 200. Flow simulation over a NACA0002 airfoil at Re = 1000 using unstructured grid based solver is also reported. The vortex shedding phenomena is mainly investigated in the flow. It is observed that the nature of flow depends strongly on the value of the Reynolds number. The present results are found to be in satisfactory agreement with several numerical results and a few experimental results available from literature

Impact of COVID-19 on clinical trials and clinical research: A systematic review

Background: The World Health Organization has reported more than 31,186,000 confirmed cases of coronavirus disease-19 (COVID-19), including 962,343 deaths, worldwide as on September 21, 2020. The current COVID-19 pandemic is affecting clinical research activities in most parts of the world. The focus on developing a vaccine for SARS-CoV-2 and the treatment of COVID-19 is, in fact, disrupting many upcoming and/or ongoing clinical trials on other diseases around the globe. On March 18, 2020, the United States Food and Drug Administration (FDA) issued an updated guideline for the conduct of clinical trials during the current health emergency situation. The potential challenges, such as social distancing and quarantines, result in study participants’ inaccessibility and trial personnel for in-person scheduled study visits and/or follow-up. Due to the sudden onset and wide-spread impact of COVID-19, its influence on the management of clinical trials and research necessitates urgent attention. Therefore, our systematic review of the literature aims to assess the impact of the COVID-19 pandemic on the conduction of clinical trials and research. The search for the relevant articles for review included the keywords "COVID-19” AND "clinical trial" in PubMed, MEDLINE, Embase, Google scholar and Google electronic databases. Key findings include: delaying subject enrollment and operational gaps in most ongoing clinical trials, which in turn has a negative impact on trial programmes and data integrity. Globally, most sites conducting clinical trials other than COVID-19 are experiencing a delay in timelines and a complete halt of operations in lieu of this pandemic, thus affecting clinical research outcomes