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Quadratic Term (quadratic + term)

Distribution by Scientific Domains

Engineering	33%
Chemistry	33%

Terms modified by Quadratic Term

quadratic term structure models

Selected Abstracts

Studies on some singular potentials in quantum mechanics

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 6 2005
Amlan K. RoyArticle first published online: 10 MAY 200
Abstract A simple methodology is suggested for the efficient calculation of certain central potentials having singularities. The generalized pseudospectral method used in this work facilitates nonuniform and optimal spatial discretization. Applications have been made to calculate the energies, densities, and expectation values for two singular potentials of physical interest, viz., (i) the harmonic potential plus inverse quartic and sextic perturbation and (ii) the Coulomb potential with a linear and quadratic term for a broad range of parameters. The first 10 states belonging to a maximum of ,, = 8 and 5 for (i) and (ii) have been computed with good accuracy and compared with the most accurate available literature data. The calculated results are in excellent agreement, especially in light of the difficulties encountered in these potentials. Some new states are reported here for the first time. This offers a general and efficient scheme for calculating these and other similar potentials of physical and mathematical interest in quantum mechanics accurately. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source]

Numerical computation of cross-coupled algebraic Riccati equations related to H2/H, control problem for singularly perturbed systems

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 8 2004
Hiroaki Mukaidani
Abstract In this paper, we present a numerical algorithm to the cross-coupled algebraic Riccati equations(CARE) related to H2/H, control problems for singularly perturbed systems (SPS) by means of Newton's method. The resulting algorithm can be widely used to solve Nash game problems and robust control problems because the CARE is solvable even if the quadratic term has an indefinite sign. We prove that the resulting iterative algorithm has the property of the quadratic convergence. Using the solution of the CARE, we construct the high-order approximate H2/H, controller. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Antifungal Activity Stability of Flaxseed Protein Extract Using Response Surface Methodology

JOURNAL OF FOOD SCIENCE, Issue 1 2008
Y. Xu
ABSTRACT:, The stability of the antifungal activity of flaxseed (Linum usitatissimum) protein extract was evaluated in this study. Response surface methodology (RSM) using Box,Behnken factorial design was used to evaluate the effects of treatment variables, that is, temperature (50 to 90 °C), time (1 to 29 min), and pH (2 to 8), on the residual antifungal activity (RAA) against Penicillium chrysogenum, Fusarium graminearum, Aspergillus flavus, and a Penicillium sp. isolated from moldy noodles. Regression analyses suggested that the linear terms of the temperature and time had significant (P < 0.05) negative effects on the RAA against all test fungi, whereas that of pH had a significant (P < 0.1) positive role on the RAA of all 3 fungi. In addition, the RAA was significantly (P < 0.05) affected by the quadratic terms of time for all fungi, and the quadratic term of temperature played a significant (P < 0.1) role on RAA against F. graminearum. One interaction term (temperature-pH) was found to significantly (P < 0.1) affect the RAA against both Penicillium strains tested. The results indicated that , 90% antifungal activity was lost after the protein extracts were heated at 90 °C for 8 min except for F. graminearum. At pasteurization condition, , 50% activity was retained except for P. chrysogenum. The results also suggested that neutral and alkaline pH favored the antifungal activity stability of the protein extracts. Thus, flaxseed protein might be promising if used as a preservative in foods with neutral or alkaline pH requiring mild heat treatments. [source]

Estimating the Relative Efficiency of Brazilian Publicly and Privately Owned Water Utilities: A Stochastic Cost Frontier Approach,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 5 2007
Geraldo Da Silva e Souza
R15; R38 Abstract:, This paper assesses cost efficiencies of Brazilian public and private companies of water supply. To measure the efficiency, we used a stochastic frontier model derived from the translog family , a specification similar to a Cobb-Douglas including a quadratic term in log output. The model parameters are estimated by maximum likelihood using Brazilian data for the year 2002. Statistical inference leads to the conclusion that there is no evidence that private firms and public firms are significantly different in terms of efficiency measurements. [source]

The white dwarf in AE Aqr brakes harder

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006
Christopher W. Mauche
ABSTRACT Taking advantage of the very precise de Jager et al. optical white dwarf orbit and spin ephemerides; ASCA, XMM,Newton and Chandra X-ray observations spread over 10 yr; and a cumulative 27-yr baseline, we have found that in recent years the white dwarf in AE Aqr is spinning down at a rate that is slightly faster than predicted by the de Jager et al. spin ephemeris. At the present time, the observed period evolution is consistent with either a cubic term in the spin ephemeris with , which is inconsistent in sign and magnitude with magnetic dipole radiation losses, or an additional quadratic term with , which is consistent with a modest increase in the accretion torques spinning down the white dwarf. Regular monitoring, in the optical, ultraviolet and/or X-rays, is required to track the evolution of the spin period of the white dwarf in AE Aqr. [source]

Longitudinal Examination of the Relationship Between Supplies,Values Fit and Work Outcomes

APPLIED PSYCHOLOGY, Issue 1 2001
Ruben Taris
This study focuses on the robustness of the relationship between supplies,values (S,V) fit and work outcomes. Specifically, the functional form that best describes the relationships of three different dimensions of S,V fit (i.e. intrinsic work aspects, extrinsic work aspects, and social relations at work) with job satisfaction, intention to leave the organisation and psychological well-being was investigated using the moderated regression technique proposed by Edwards (1991, 1994). This study extends previous research by examining the stability of these relationships across two occasions, separated by a period of four years. Results showed that the functional form of the relationship of S,V fit with work outcomes differed by the S,V fit dimension and the work outcome under investigation. However, the functional form of each of these relationships on the first occasion was almost identical to the form of the relationships on the second occasion. Additionally, results showed that all three S,V fit dimensions affected job satisfaction and intention to leave, but had only a weak effect on psychological well-being. The organisational supplies component, as well as its quadratic term in particular, had a large influence on job satisfaction and intention to leave. Implications for future research in the P,O fit area are discussed. Cette e´tude est centre´e sur la force de la relation entre la correspondance contributions-valeurs (supplies-values ou S,V) et les re´sultats du travail. Plus particulie`rement, la forme fonctionnelle qui de´crit le mieux les rapports des trois dimensions de la correspondance S,V (c'est-a`-dire les relations sociales au travail et les aspects intrinse`ques et extrinse`ques du travail) avec la satisfaction professionnelle, le projet de quitter l'organisation et le bien-être psychologique a e´te´ explore´e a` l'aide de la technique de la re´gression mode´re´e propose´e par Edwards (1991, 1994). Cette recherche e´largit les travaux ante´rieurs en s'inte´ressant a` la stabilite´ de ces relations a` deux pe´riodes se´pare´es par un laps de temps de quatre ans. Les analyses montrent que la forme fonctionnelle de la relation de la correspondance S,V avec les re´sultats du travail diffe´rent selon les dimensions de la correspondance S,V et selon les aspects des re´sultats du travail pris en conside´ration. Cependant, la forme fonctionnelle de chacune de ces relations sur la premie`re pe´riode e´tait presque identique a` la forme des relations sur la seconde. En outre, les analyses montrent que les trois dimensions de la correspondance S,V affectent la satisfaction professionnelle et le projet de de´mission, mais n'ont qu'un faible effet sur le bien-être psychologique. La composante "contribution organisationnelle", aussi bien que son terme quadratique en particulier, a une grande influence sur la satisfaction professionnelle et le projet de de´part. On discute aussi des retombe´es sur les futures recherches dans le domaine personne-organisation. [source]

Gaussian Process Based Bayesian Semiparametric Quantitative Trait Loci Interval Mapping

BIOMETRICS, Issue 1 2010
Hanwen Huang
Summary In linkage analysis, it is often necessary to include covariates such as age or weight to increase power or avoid spurious false positive findings. However, if a covariate term in the model is specified incorrectly (e.g., a quadratic term misspecified as a linear term), then the inclusion of the covariate may adversely affect power and accuracy of the identification of quantitative trait loci (QTL). Furthermore, some covariates may interact with each other in a complicated fashion. We implement semiparametric models for single and multiple QTL mapping. Both mapping methods include an unspecified function of any covariate found or suspected to have a more complex than linear but unknown relationship with the response variable. They also allow for interactions among different covariates. This analysis is performed in a Bayesian inference framework using Markov chain Monte Carlo. The advantages of our methods are demonstrated via extensive simulations and real data analysis. [source]

Multiobjective control via successive over-bounding of quadratic terms

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 8 2005
Takashi Shimomura
Abstract This paper addresses less conservative control design for multiple design specifications. Problems are described by a set of linear matrix inequalities (LMIs) and solved with non-common LMI solutions in order to reduce the conservatism arising from seeking a common LMI solution in the past results. Noticing that completing the square can split two variables in bilinear matrix inequality (BMI) terms into two different LMI ones, we propose an iterative algorithm in which non-positive quadratic terms are successively replaced by their upper bounds. An illustrated example is included. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Age-related change in breeding performance in early life is associated with an increase in competence in the migratory barn swallow Hirundo rustica

JOURNAL OF ANIMAL ECOLOGY, Issue 5 2007
JAVIER BALBONTÍN
Summary 1We investigated age-related changes in two reproductive traits (laying date and annual fecundity) in barn swallows Hirundo rustica L. using a mixed model approach to di-stinguish among between- and within-individual changes in breeding performance with age. 2We tested predictions of age-related improvements of competence (i.e. constraint hypothesis) and age-related progressive disappearance of poor-quality breeders (i.e. selection hypothesis) to explain age-related increase in breeding performance in early life. 3Reproductive success increased in early life, reaching a plateau at middle age (e.g. at 3 years of age) and decreasing at older age (> 4 years). Age-related changes in breeding success were due mainly to an effect of female age. 4Age of both female and male affected timing of reproduction. Final linear mixed effect models (LME) for laying date included main and quadratic terms for female and male age, suggesting a deterioration in reproductive performance at older age for both males and females. 5We found evidence supporting the constraints hypothesis that increases in competence within individuals, with ageing being the most probable cause of the observed increase in breeding performance with age in early life. Two mechanisms were implicated: (1) advance in male arrival date with age provided middle-aged males with better access to mates. Yearling males arrived later to the breeding grounds and therefore had limited access to high-quality mates. (2) Breeding pairs maintaining bonds for 2 consecutive years (experienced pairs) had higher fecundity than newly formed inexperienced breeding pairs. 6There was no support for the selection hypothesis because breeding performance was not correlated with life span. 7We found a within-individual deterioration in breeding and migratory performance (arrival date) in the oldest age-classes consistent with senescence in these reproductive and migratory traits. [source]

Fungistatic Activity of Heat-Treated Flaxseed Determined by Response Surface Methodology

JOURNAL OF FOOD SCIENCE, Issue 6 2008
Y. Xu
ABSTRACT:, The objective of this study was to evaluate the effect of heat treatment on the fungistatic activity of flaxseed (Linum usitatissimum) in potato dextrose agar (PDA) medium and a fresh noodle system. The radial growth of Penicillium chrysogenum, Aspergillus flavus, and a Penicillium sp. isolated from moldy noodles, as well as the mold count of fresh noodle enriched with heat treated flaxseed, were used to assess antifungal activity. A central composite design in the response surface methodology was used to predict the effect of heating temperature and time on antifungal activity of flaxseed flour (FF). Statistical analysis determined that the linear terms of both variables (that is, heating temperature and time) and the quadratic terms of the heating temperature had significant (P < 0.05) effects on the radial growth of all 3 test fungi and the mold count log-cycle reduction of fresh noodle. The interactions between the temperature and time were significant for all dependent variables (P < 0.05). Significant reductions in antifungal activities were found when FF was subjected to high temperatures, regardless of heating time. In contrast, prolonging the heating time did not substantially affect the antifungal activities of FF at low temperature. However, 60% of the antifungal activity was retained after FF was heated at 100 °C for 15 min, which suggests a potential use of FF as an antifungal additive in food products subjected to low to mild heat treatments. [source]