Search results for " Variation"
showing 10 items of 1712 documents
Estimating field-saturated soil hydraulic conductivity by a simplified Beerkan infiltration experiment
2012
Field-saturated soil hydraulic conductivity, Kfs, is highly variable. Therefore, interpreting and simulating hydrological processes, such as rainfall excess generation, need a large number of Kfs data even at the plot scale. Simple and reasonably rapid experiments should be carried out in the field. In this investigation, a simple infiltration experiment with a ring inserted shortly into the soil and the estimation of the so-called α* parameter allowed to obtain an approximate measurement of Kfs. The theoretical approach was tested with reference to 149 sampling points established on Burundian soils. The estimated Kfs with the value of first approximation of α* for most agricultural field s…
The Poisson problem: A comparison between two approaches based on SPH method
2012
Abstract In this paper two approaches to solve the Poisson problem are presented and compared. The computational schemes are based on Smoothed Particle Hydrodynamics method which is able to perform an integral representation by means of a smoothing kernel function by involving domain particles in the discrete formulation. The first approach is derived by means of the variational formulation of the Poisson problem, while the second one is a direct differential method. Numerical examples on different domain geometries are implemented to verify and compare the proposed approaches; the computational efficiency of the developed methods is also studied.
The International Business Cycle in a Changing World: Volatility and the Propagation of Shocks
2003
This paper examines the changing relationships between the G-7 countries through VAR models for the quarterly growth rates, estimated both over sub-periods and using a rolling data window. Six trivariate models are estimated, all of which include the US and a European (E15) aggregate. In relative terms, the conditional volatility of E15 growth has declined more since 1980 than the well-documented decline for the US. The propagation of shocks has also changed, with the volatility and propagation effects separated by applying shocks of pre-1980 magnitude to VARs estimated over various periods. Rolling estimation reveals that E15 has a steadily increasing impact on the US economy over time, wh…
Intra‐ and inter‐instrument reliability of the Actiwatch 4 accelerometer in a mechanical laboratory setting.
2012
Intra- and Inter-Instrument Reliability of the Actiwatch 4 Accelerometer in a Mechanical Laboratory Setting This study aimed to quantify the intra-and inter-instrument reliability of the Actiwatch 4 accelerometer (AW4) in a mechanical setting. Twenty seven AW4 were attached to an isokinetic dynamometer and subjected to angular acceleration for 30 min at 50 deg/sec representing moderate intensity (MPA condition) and 200 deg/sec representing vigorous intensity (VPA condition), with a repeat trial conducted. Reliability was assessed using coefficient of variation (CV), absolute percent error (APE), and intraclass correlation coefficients (ICC). Mean AW4 activity counts displayed acceptable rel…
Large diurnal variation of intraocular pressure in open angle glaucoma in subjects with type A behaviour pattern
2014
Aim : To evaluate the possible causes of the greater perimetric damage found in OAG subjects with type A behaviour and the possible role of psycho-physiological stress. Materials and methods : 80 patients with OAG, 44 women and 36 men, 40 with type A behaviour and 40 with type B studied with the Type A/B Personality Questionnaire (A modified version of the Jenkins Activity Survey), underwent a complete ophthalmologic examination consisting of bio-microscopy, tonometry and daily tonometric curve, examination of the visual field by means of Octopus 1-2-3 computerised perimeter and its assessment with the Glaucoma Staging System 2 (GSS2), morphological monitoring of the Retinal Nerve Fibre Lay…
Genetic diversity in populations of asexual and sexual bag worm moths (Lepidoptera: Psychidae).
2004
Abstract Background Despite the two-fold cost of sex, most of the higher animals reproduce sexually. The advantage of sex has been suggested to be its ability, through recombination, to generate greater genetic diversity than asexuality, thus enhancing adaptation in a changing environment. We studied the genetic diversity and the population structure of three closely related species of bag worm moths: two strictly sexual (Dahlica charlottae and Siederia rupicolella) and one strictly asexual (D. fennicella). These species compete for the same resources and share the same parasitoids. Results Allelic richness was comparable between the sexual species but it was higher than in the asexual spec…
ETAT: Expository Text Analysis Tool.
2002
Qualitative methods that analyze the coherence of expository texts not only are time consuming, but also present challenges in collecting data on coding reliability. We describe software that analyzes expository texts more rapidly and produces a notable level of objectivity. ETAT (Expository Text Analysis Tool) analyzes the coherence of expository texts. ETAT adopts a symbolic representational system, known as conceptual graph structures. ETAT follows three steps: segmentation of a text into nodes, classification of the unidentified nodes, and linking the nodes with relational arcs. ETAT automatically constructs a graph in the form of nodes and their interrelationships, along with various a…
An Existence Result for Fractional Kirchhoff-Type Equations
2016
The aim of this paper is to study a class of nonlocal fractional Laplacian equations of Kirchhoff-type. More precisely, by using an appropriate analytical context on fractional Sobolev spaces, we establish the existence of one non-trivial weak solution for nonlocal fractional problems exploiting suitable variational methods.
The case for strategic international alliances to harness nutritional genomics for public and personal health
2005
Nutrigenomics is the study of how constituents of the diet interact with genes, and their products, to alter phenotype and, conversely, how genes and their products metabolise these constituents into nutrients, antinutrients, and bioactive compounds. Results from molecular and genetic epidemiological studies indicate that dietary unbalance can alter gene-nutrient interactions in ways that increase the risk of developing chronic disease. The interplay of human genetic variation and environmental factors will make identifying causative genes and nutrients a formidable, but not intractable, challenge. We provide specific recommendations for how to best meet this challenge and discuss the need …
Fixed point iterative schemes for variational inequality problems
2018
In a wide class of evolutionary processes, the problem of computing the solutions of an initial value problem is encountered. Here, we consider projected dynamical systems in the sense of \cite{Daniele} and references therein. Precisely, a projected dynamical system is an operator which solves the initial value problem: \begin{equation}\label{PDS}\frac{dx(t)}{dt}= \Pi_{\mathbb{K}}\left(x(t),-F(x(t))\right), \quad x(0)=x_0 \in \mathbb{K}, \, t \in [0,+\infty[,\tag{P}\end{equation} where $\mathbb{K}$ is a convex polyhedral set in $\mathbb{R}^n$, $F: \mathbb{K} \to \mathbb{R}^n$ and $\Pi_{\mathbb{K}}: \mathbb{R} \times \mathbb{K} \to \mathbb{R}^n$ is given as follows $\Pi_{\mathbb{K}}(x,-F(x))…