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Long Wavelength Analysis of a Model for the Geographic Spread of a Disease
Get PDFWe investigate the temporal and spatial evolution of the spread of an infectious disease by performing a long-wavelength analysis of a classical model for the geographic spread of a rabies epidemic in a population of foxes subject to idealized boundary conditions. We consider twodimensional and three-dimensional landscapes consisting of an infinite horizontal strip bounded by two walls a finite distance apart and a horizontal region bounded above and below by horizontal walls, respectively. A nonlinear partial differential evolution Equation for the leading order of infectives is derived. The Equation captures the space and time variations of the spread of the disease in the weakly super critical region
A Likelihood Ratio Test Approach to Profile Monitoring in Tourism Industry
Get PDFA new statistical profile monitoring technique to monitor and detect changes in logistic profiles with an application in the tourism industry is presented in this paper. In the statistical process control literature, profile is usually referred to as a relationship between a response variable and one or more explanatory variables. In the tourism case study presented in this paper, time is considered as the explanatory variable and tourism satisfaction as the response variable. The Likelihood ratio test is used as a vehicle to detect any changes in the satisfaction profile in phase II of profile monitoring. The performance of the proposed method is evaluated using the average run length criterion. The numerical data indicate satisfactory results for the proposed approach
Fabrication of BSA loaded poly (Caprolactone) (PCL)/ hydroxyapatite (HA) composite microsphere for tissue engineering application
No full textIn this study, PCL microsphere has been synthesised using the double emulsion technique and a freeze dry technique. Bovine Serum Albumin (BSA) was added as a model protein and Hydroxyapatite (HA) to enhance osteoconductivity properties of the microsphere. Poly (caprolactone) (PCL)-based microspheres were synthesized and characterized. Microspheres were produced with 5%, 10%, and 15% (w/v) PCL solution (30mL) by dissolving different amounts of PCL in dichloromethane (DCM). Microspheres produced from 5% (w/v) PCL concentration had an average diameter of 100 – 120 μm. Bovine serum albumin (BSA) (0.04% w/v) and 10% w/w of HA powder were added into the microspheres produced from 5% (w/v) PCL concentration. The microsphere was then characterized using different techniques and in vitro release study of BSA was conducted. Prepared microsphere showed good potential for bone tissue engineering
Fabrication and in vitro evaluation of nanosized hydroxyapatite/chitosan- based tissue engineering scaffolds
No full textComposite scaffolds based on biodegradable natural polymer and osteoconductive hydroxyapatite (HA) nanoparticles can be promising for a variety of tissue engineering (TE) applications. This study addressed the fabrication of three-dimensional (3D) porous composite scaffolds composed of HA and chitosan fabricated via thermally induced phase separation and freeze-drying technique. The scaffolds produced were subsequently characterized in terms of microstructure, porosity, and mechanical property. In vitro degradation and in vitro biological evaluation were also investigated. The scaffolds were highly porous and had interconnected pore structures. The pore sizes ranged from several microns to a few hundred microns. The incorporated HA nanoparticles were well mixed and physically coexisted with chitosan in composite scaffold structures. The addition of 10% (w/w) HA nanoparticles to chitosan enhanced the compressive mechanical properties of composite scaffold compared to pure chitosan scaffold. In vitro degradation results in phosphate buffered saline (PBS) showed slower uptake properties of composite scaffolds. Moreover, the scaffolds showed positive response to mouse fibroblast L929 cells attachment. Overall, the findings suggest that HA/chitosan composite scaffolds could be suitable for TE applications. © 2014 Tao Sun et al
Optimal Investment in Heterogeneous Capital and Technology Under Restricted Natural Resource
No full textWe consider the optimal control of nonlinear integral equations with endogenous delay and state constraints, which describe a developing economy subjected to resource constraints. The economy invests in new resource-efficient technologies, invests in new capital, and scraps obsolete capital. We derive the optimality condition and determine long-term asymptotically exponential trajectories that optimally combine scrapping the dirtiest capital and developing new clean technologies. Next, we study the short-term dynamics of the model and show that it leads to a sustainable growth with active resource constraint
Construction scheduling using Genetic Algorithm based on Building Information Model
No full textThe construction project schedule is one of the most important tools for project managers in the Architecture, Engineering, and Construction (AEC) industry that makes them able to track and manage the time, cost, and quality (a.k.a. Project Management Triangle) of projects. Developing project schedules is almost always troublesome, since it is heavily dependent on project planners\u27 knowledge of work packages, on-the-job-experience, planning capability and oversight. Having a thorough understanding of the project geometries and their internal interacting stability relations plays a significant role in generating practical construction sequencing. On the other hand, the new concept of embedding all the project information into a 3-dimensional representation of a project (a.k.a. Building Information Model or BIM) has recently drawn attention to the construction industry. In this paper, the authors demonstrate a novel approach of retrieving enough information from the BIM of a project and then develop construction sequencing for the installation of the project elements. For this reason a computer application is developed that can automatically derive a structurally (statically) stable construction sequence, using the concept of the Genetic Algorithm (GA). The term structurally stable sequencing in this article refers to the sequencing order of erection in which the structure remains statically stable locally and globally during the entire installation process. To validate the proposed methodology, the authors designed 21 different experiments and used the proposed method for generating stable construction schedules, which all were successfully accomplished. Therefore, this methodology proposes a novel approach of construction project application of the GA, as an Expert System tool. © 2014 Elsevier Ltd. All rights reserved
Mathematical expressions for a system of two identical uniformly charged rods
No full textUniformly charged bodies with various symmetries are of great interest to many models in several disciplines. In particular, there are numerous physical and biological systems that contain rod-like charged particles. In this work, we consider a system of two identical uniformly charged rods and calculate their electrostatic interaction energy for a special case of orientation between them. A first approach that relies on standard integration methods allows us to obtain an exact analytic expression for such an interaction in this case. Application of a second different method to the same problem leads to mathematical expressions involving generalized hypergeometric functions, a class of special functions not frequently encountered in the field. Comparison of the two results leads to interesting mathematical identities that might be of interest to a broad audience of researchers working in mathematical and physical sciences
Molecular, cellular, and physiological determinants of bull fertility
No full textBull fertility, defined as the ability of the spermatozoon to fertilize and activate the ovum and then support embryonic and even fetal development, is a crucial factor influencing animal reproduction and production efficiency. Despite significant influences of fertility on herd genetic improvement and efficient cattle production, the mechanisms regulating this phenotype and reliable biomarkers associated with bull fertility are poorly defined. Specifically, there is a broad lack of knowledge in bull fertility. In this paper, bull fertility is reviewed within the context of animal systems physiology, and system biology markers associated with bull fertility are provided. This mini-review is intended to be a useful resource for students, animal producers, and the general public to help understand and appreciate this economically important trait