Complex zero strip decreasing operators

In this paper we study the effect of linear differential operators coming from the Laguerre-Polya class that act on functions in the extended Laguerre-Polya class with zeros in a horizontal strip in the complex plane. These operator decrease the size of the strip containing the zeros.Comment: 17 pages, corrected several typos, added a citation. appears in Math. Anal. Appl. (2015

Extended Laguerre inequalities and a criterion for real zeros

Let $f(z)=e^{-bz^2}f_1(z)$ where $b \geq 0$ and $f_1(z)$ is a real entire function of genus 0 or 1. We give a necessary and sufficient condition in terms of a sequence of inequalities for all of the zeros of $f(z)$ to be real. These inequalities are an extension of the classical Laguerre inequalities.Comment: The paper is based on a talk given at the 7th ISAAC Congress held at Imperial College in London in July 200

The nonlinear viscoelastic response of resin matrix composite laminates

Possible treatments of the nonlinear viscoelastic behavior of materials are reviewed. A thermodynamic based approach, developed by Schapery, is discussed and used to interpret the nonlinear viscoelastic response of a graphite epoxy laminate, T300/934. Test data to verify the analysis for Fiberite 934 neat resin as well as transverse and shear properties of the unidirectional T300/934 composited are presented. Long time creep characteristics as a function of stress level and temperature are generated. Favorable comparisons between the traditional, graphical, and the current analytical approaches are shown. A free energy based rupture criterion is proposed as a way to estimate the life that remains in a structure at any time

A STUDY ON DYNAMIC SYSTEMS RESPONSE OF THE PERFORMANCE CHARACTERISTICS OF SOME MAJOR BIOPHYSICAL SYSTEMS

Dynamic responses of biophysical systems - performance characteristic

Dimension Reduction via Colour Refinement

Colour refinement is a basic algorithmic routine for graph isomorphism testing, appearing as a subroutine in almost all practical isomorphism solvers. It partitions the vertices of a graph into "colour classes" in such a way that all vertices in the same colour class have the same number of neighbours in every colour class. Tinhofer (Disc. App. Math., 1991), Ramana, Scheinerman, and Ullman (Disc. Math., 1994) and Godsil (Lin. Alg. and its App., 1997) established a tight correspondence between colour refinement and fractional isomorphisms of graphs, which are solutions to the LP relaxation of a natural ILP formulation of graph isomorphism. We introduce a version of colour refinement for matrices and extend existing quasilinear algorithms for computing the colour classes. Then we generalise the correspondence between colour refinement and fractional automorphisms and develop a theory of fractional automorphisms and isomorphisms of matrices. We apply our results to reduce the dimensions of systems of linear equations and linear programs. Specifically, we show that any given LP L can efficiently be transformed into a (potentially) smaller LP L' whose number of variables and constraints is the number of colour classes of the colour refinement algorithm, applied to a matrix associated with the LP. The transformation is such that we can easily (by a linear mapping) map both feasible and optimal solutions back and forth between the two LPs. We demonstrate empirically that colour refinement can indeed greatly reduce the cost of solving linear programs

Determining the Price-Responsiveness of Demands for Irrigation Water Deliveries versus Consumptive Use

A water-crop simulation/mathematical programming model of irrigation water demand in northeastern Colorado is formulated to develop an original concept of derived demand for consumptive use of water. Conventional demand functions for water deliveries are also developed, and the effect of hypothetical price increases on both consumption and delivery are illustrated. Findings indicate that demand elasticity estimates are quite sensitive to model specification, and consumptive use demand tends to be significantly less price-responsive than delivery demand. Thus price incentives are likely to have only limited impacts on basin-wide water consumption and would not make much additional water available for emerging demands.crop simulation, irrigation, mathematical programming, water conservation, water-demand elasticities, water policy, Demand and Price Analysis, Resource /Energy Economics and Policy,

Study of the processing and properties of mixtures of recycled plastics for outdoor applications

There is an industrial need for the study of the mechanical and physical properties of recycled polyolefins mixed with cellulose fibres from diapers, wood and packaging containing aluminium. The recycling of thermoplastic based residues is economically very interesting for the easy reprocessing of these materials and flexible shaping using conventional moulding processes as injection moulding or intrusion. Various mixtures of these materials were characterized in terms of their constituents and properties determined using 200 mm square mouldings of 10 mm and 5 mm thickness, in view of their potential application in urban furniture. These mouldings were processed by injection moulding and by intrusion that is a method which uses and extruder for delivering the melt directly into an injection mould. The mouldings were tested in terms of theirmechanical performance in impact and flexion. The intrusion process yielded mouldings with properties similar to injection moulding but appeared to be more attractive for requiring lower moulding pressure and thus lighter and cheaper tooling. The morphology of the mouldings, observed by bright field light microscopy showed some contamination and voiding associated to specific processing conditions and moulding size, the thinner mouldings having less voids than the 10 mm thick. The higher voiding in the thicker mouldings was detrimental to the flexural and impact performances of the parts. The coefficient of linear thermal expansion was determined and showed to be sensitive to the percentage of LDPE and fibres in the mixtures. The flexural stiffness of the moulded plates was assessed using the whole mouldings in the 3-point support test and showed the positive influence of the wood fibres and the diaper content in the mixtures. Conversely the impact performance assessed by the Charpy test was affected by the diaper content, but benefitted from the presence of aluminium from the recycled packaging. The prediction of these properties using the law of mixtures for predicting the overall density in the mouldings was not particularly accurate for the mixtures with recycled diapers.European Commission for Education and Training, Erasmus placement scholarship at Hogeschool Gen

Associations of neighborhood characteristics with active park use : an observational study in two cities in the USA and Belgium

Background: Public parks can be an important setting for physical activity promotion, but to increase park use and the activity levels of park users, the crucial attributes related to active park use need to be defined. Not only user characteristics and structural park attributes, but also characteristics of the surrounding neighborhood are important to examine. Furthermore, internationally comparable studies are needed, to find out if similar intervention strategies might be effective worldwide. The main aim of this study was to examine whether the overall number of park visitors and their activity levels depend on study site, neighborhood walkability and neighborhood income. Methods: Data were collected in 20 parks in Ghent, Belgium and San Diego, USA. Two trained observers systematically coded park characteristics using the Environmental Assessment of Public Recreation Spaces (EAPRS) tool, and park user characteristics using the System for Observing Play and recreation in Communities (SOPARC) tool. Multilevel multiple regression models were conducted in MLwiN 2.25. Results: In San Diego parks, activity levels of park visitors and number of vigorously active visitors were higher than in Ghent, while the number of visitors walking and the overall number of park visitors were lower. Neighborhood walkability was positively associated with the overall number of visitors, the number of visitors walking, number of sedentary visitors and mean activity levels of visitors. Neighborhood income was positively associated with the overall number of visitors, but negatively with the number of visitors being vigorously active. Conclusions: Neighborhood characteristics are important to explain park use. Neighborhood walkability-related attributes should be taken into account when promoting the use of existing parks or creating new parks. Because no strong differences were found between parks in high-and low-income neighborhoods, it seems that promoting park use might be a promising strategy to increase physical activity in low-income populations, known to be at higher risk for overweight and obesity

General dynamics of the physical-chemical systems in mammals

Biodynamic regulator chain models for physical chemical systems in mammal

Investigation of quantitative measures related to reading disability in a large sample of sib-pairs from the UK

We describe a family-based sample of individuals with reading disability collected as part of a quantitative trait loci (QTL) mapping study. Eighty-nine nuclear families (135 independent sib-pairs) were identified through a single proband using a traditional discrepancy score of predicted/actual reading ability and a known family history. Eight correlated psychometric measures were administered to each sibling, including single word reading, spelling, similarities, matrices, spoonerisms, nonword and irregular word reading, and a pseudohomophone test. Summary statistics for each measure showed a reduced mean for the probands compared to the co-sibs, which in turn was lower than that of the population. This partial co-sib regression back to the mean indicates that the measures are influenced by familial factors and therefore, may be suitable for a mapping study. The variance of each of the measures remained largely unaffected, which is reassuring for the application of a QTL approach. Multivariate genetic analysis carried out to explore the relationship between the measures identified a common factor between the reading measures that accounted for 54% of the variance. Finally the familiality estimates (range 0.32–0.73) obtained for the reading measures including the common factor (0.68) supported their heritability. These findings demonstrate the viability of this sample for QTL mapping, and will assist in the interpretation of any subsequent linkage findings in an ongoing genome scan