Fluctuation and stability in a diffusive predator-prey system

AbstractRecently a deterministic Predator-Prey model which takes into account low predator densities has been discussed by Smith [1]. In the present paper we have studied the stochastic behavior of this model with diffusion

A production inventory model with deteriorating items and shortages

A continuous production control inventory model for deteriorating items with shortages is developed. A number of structural properties of the inventory system are studied analytically. The formulae for the optimal average system cost, stock level, backlog level and production cycle time are derived when the deterioration rate is very small. Numerical examples are taken to illustrate the procedure of finding the optimal total inventory cost, stock level, backlog level and production cycle time. Sensitivity analysis is carried out to demonstrate the effects of changing parameter values on the optimal solution of the system

Application of Bayesian analysis on risk factors of coronary artery disease

Ischemic heart disease (or Coronary Artery Disease) is the most common cause of death in various countries, characterized by reduced blood supply to the heart. Statistical models make an impact for evaluating the risk factors which are responsible for mortality and morbidity during IHD (Ischemic heart disease). In this work, due to count data, we propose Poisson, Negative Binomial and also utilize a flexible class of zero inflated models such as Zero-Inflated Poisson (ZIP) and Zero-Inflated Negative Binomial (ZINB) models estimated by the method of MLE and are compared to assess the most appropriate model for the underlying data.  The forward and backward model selection procedures are also taken to permit the most significant factors associated with heart disease. The ZIP model is identified as the most appropriate one in this work. Moreover, a Bayesian estimation is chosen to account for prior on regression coefficients in a small sample size setting. This estimation also evolves as an alternative to traditionally used MLE based methods for such data. As per our simulation studies: the proposed method has better finite sample performance than the classical method with tighter interval estimates and better coverage probabilities. The simulation is based on R-software

Transverse momentum spectra of charged particles in proton-proton collisions at s=900\sqrt{s} = 900 GeV with ALICE at the LHC

The inclusive charged particle transverse momentum distribution is measured in proton-proton collisions at $\sqrt{s} = 900$ GeV at the LHC using the ALICE detector. The measurement is performed in the central pseudorapidity region $(|\eta|<0.8)$ over the transverse momentum range $0.15<p_{\rm T}<10$ GeV/$c$. The correlation between transverse momentum and particle multiplicity is also studied. Results are presented for inelastic (INEL) and non-single-diffractive (NSD) events. The average transverse momentum for $|\eta|<0.8$ is $\left<p_{\rm T}\right>_{\rm INEL}=0.483\pm0.001$ (stat.) $\pm0.007$ (syst.) GeV/$c$ and \left_{\rm NSD}=0.489\pm0.001 (stat.) $\pm0.007$ (syst.) GeV/$c$, respectively. The data exhibit a slightly larger $\left<p_{\rm T}\right>$ than measurements in wider pseudorapidity intervals. The results are compared to simulations with the Monte Carlo event generators PYTHIA and PHOJET.Comment: 20 pages, 8 figures, 2 tables, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/390

A Deterministic Inventory System with Weibull Distribution Deterioration and Ramp Type Demand Rate

A continuous order-level inventory model is developed for deteriorating items with a ramp type demand function of time. A two parameter Weibull distribution is taken to represent the time to  deterioration. The model is solved analytically by enumerating two possible shortage models to obtain the optimal solution of the problem. The method is illustrated by two numerical examples and sensitivity analysis of the optimal solutions with respect to the parameters of the system are carried out

Optimal inventory policies for imperfect inventory with price dependent stochastic demand and partially backlogged shortages

The paper investigates a single period imperfect inventory model with price dependent stochastic demand and partial backlogging. The backorder rate is a nonlinear non-increasing function of the magnitude of shortage. Two special cases are considered assuming that the percentage of defective items follows a truncated exponential distribution and a normal distribution respectively. The optimal order quantity and the optimal mark up value are determined such that the expected total profit of the system is maximized. Numerical example is given to illustrate the proposed model which is compared with the traditional model of perfect stock. Sensitivity analysis is performed to explain the behavior of the proposed model with respect to the key parameters

On stability and fluctuation in Gompertzian and logistic growth models

AbstractThis paper aims to study the influence of colored noise to Gompertzian and Logistic growth models. The discussion is based on the complex stochastic averaging technique

The reception of Rome in socio-political debate 1850-1920 : Empire, nation and city

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

A prey-predator system with herd behaviour of prey in a rapidly fluctuating environment

A statistical theory of non-equilibrium fluctuation in damped Volterra-Lotka prey-predator system where prey population lives in herd in a rapidly fluctuating random environment has been presented. The method is based on the technique of perturbation approximation of non-linear coupled stochastic differential equations. The characteristic of group-living of prey population has been emphasized using square root of prey density in the functional response