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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Publication Metadata only How similar are protein folding and protein binding nuclei? Examination of vibrational motions of energy hot spots and conserved residues(Cell Press, 2005) Haliloğlu, Türkan; Ma, Buyong; Nussinov, Ruth; Department of Chemical and Biological Engineering; Keskin, Özlem; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 26605The underlying physico-chemical principles of the interactions between domains in protein folding are similar to those between protein molecules in binding. Here we show that conserved residues and experimental hot spots at intermolecular binding interfaces overlap residues that vibrate with high frequencies. Similarly, conserved residues and hot spots are found in protein cores and are also observed to vibrate with high frequencies. In both cases, these residues contribute significantly to the stability. Hence, these observations validate the proposition that binding and folding are similar processes. In both packing plays a critical role, rationalizing the residue conservation and the experimental alanine scanning hot spots. We further show that high-frequency vibrating residues distinguish between protein binding sites and the remainder of the protein surface.Publication Metadata only Parallel computing in Asian option pricing(Elsevier Science Bv, 2007) Sak, Halis; Boduroglu, Ilkay; Department of Industrial Engineering; Özekici, Süleyman; Faculty Member; Department of Industrial Engineering; College of Engineering; 32631We discuss the use of parallel computing in Asian option pricing and evaluate the efficiency of various algorithms. We only focus on "backward-starting fixed strike" Asian options that are continuously averaged. We implement a partial differential equation (PDE) approach that involves a single state variable to price the Asian option, and implement the same methodology to price a standard European option to check for accuracy. A parabolic PDE is solved by using both explicit and Crank-Nicolson's implicit finite-difference methods. In particular, we look for algorithms designed for implementing the computations in massively parallel processors (MPP). We evaluate the performance of the algorithms by comparing the numerical results with respect to accuracy and wall-clock time of code executions. Codes are executed on a Linux PC cluster.Publication Metadata only Asymptotic behavior of the irrational factor(Springer, 2008) Ledoan, A. H.; Zaharescu, Alexandru; Department of Mathematics; Alkan, Emre; Faculty Member; Department of Mathematics; College of Sciences; 32803We study the irrational factor function I(n) introduced by Atanassov and defined by I(n) = Pi(k)(k=1)p(v)(1/alpha v), where n = Pi(k)(v=1) p(v)(alpha v) is the prime factorization of n. We show that the sequence {G(n)/n}(n >= 1), where G(n) = Pi(n)(v=1) I(v)(1/n), is covergent; this answers a question of Panaitopol. We also establish asymptotic formulas for averages of the function I(n).Publication Metadata only Statistical origin of pseudo-Hermitian supersymmetry and pseudo-hermitian fermions(Iop Publishing Ltd, 2004) Department of Mathematics; Mostafazadeh, Ali; Faculty Member; Department of Mathematics; College of Sciences; 4231We show that the metric operator for a pseudo-supersymmetric Hamiltonian that has at least one negative real eigenvalue is necessarily indefinite. We introduce pseudo-Hermitian fermion (phermion) and abnormal phermion algebras and provide a pair of basic realizations of the algebra of N = 2 pseudo-supersymmetric quantum mechanics in which pseudo-supersymmetry is identified with either a boson-phermion or a boson-abnormal-phermion exchange symmetry. We further establish the physical equivalence (nonequivalence) of phermions (abnormal phermions) with ordinary fermions, describe the underlying Lie algebras and study multi-particle systems of abnormal phermions. The latter provides a certain bosonization of multifermion systems.Publication Metadata only Does parent satisfaction with a childcare provider matter for loyalty?(Emerald Group Publishing, 2006) Keiningham, T.L.; Andreassen, T.W.; Estrin, D.; Department of Business Administration; Aksoy, Lerzan; Faculty Member; Department of Business Administration; College of Administrative Sciences and Economics; N/APurpose - The purpose of this study is to investigate the relationship between parent satisfaction and child retention at a childcare provider. Design/methodology/approach - The survey data used in the analyses involves a sample size of 1,003 respondents, all clients of a regional childcare provider in the USA. Logistic regression was used to test the propositions. Findings - The results indicate that parent satisfaction is most important to child retention when the child is very young (birth to one year of age). As children increase in age, however, parent satisfaction becomes increasingly less predictive of children's continued enrollment at a childcare facility. Research limitations/implications - One of the limitations of this research is that it tests the propositions within a single firm. Future research should attempt to replicate these findings across several childcare providers. Practical implications - Emphasizing improvements in different attributes for different age groups has implications for increasing retention for childcare providers, in addition to ultimately increasing the satisfaction of parents. Originality/value - While all would agree that childcare services are of extremely high importance (at both a national and individual level), no research to date has examined the role of parent satisfaction to the continued enrollment of a child at a childcare facility. Our findings show that the presumed relationship between satisfaction and retention varies greatly by the age of child.Publication Metadata only Surgery diagrams for horizontal contactstructures(Springer, 2008) N/A; Department of Mathematics; Özbağcı, Burak; Faculty Member; Department of Mathematics; College of Sciences; 29746We describe Legendrian surgery diagrams for some horizontal contact structures on non-positive plumbing trees of oriented circle bundles over spheres with negative Euler numbers. As an application we determine Millior fillable contact structures on some Milnor fillable 3-manifolds.Publication Metadata only The hazards of training: attrition and retention in construction industry apprenticeship programs(Sage, 2003) Department of Economics; Bilginsoy, Cihan; Other; Department of Economics; College of Administrative Sciences and Economics; N/AApprenticeship programs in the United States, which provide workers with the broad-based skills required for practicing a trade via on-the-job training, are sponsored either unilaterally by employers or jointly by employers and trade unions. A comparison of the attrition and retention rates in these programs shows that program completion is more likely for apprentices in joint programs than for similar apprentices in unilateral programs. Rates of completion are lower for women than for men, and lower for ethnic and racial minorities than for whites. Apprenticeship duration rises with the unemployment rate.Publication Metadata only Effect of thermal lensing on the mode matching between pump and laser beams in Cr4+: forsterite lasers: a numerical study(IOP Publishing, 2000) Department of Physics; Sennaroğlu, Alphan; Faculty Member; Department of Physics; College of Sciences; 23851The numerical study presented in this paper investigates the role of thermal lensing on the mode matching between the pump beam and the cavity beam in continuous-wave end-pumped Cr4+:forsterite lasers. A suitable mode overlap function was first derived to calculate the degree of overlap between the pump beam and the fundamental mode of the resonator. The effect of thermal lensing on mode matching was then numerically investigated by calculating the changes in the average value of the mode overlap function due to variations in pump power and crystal boundary temperature. Thermal lensing was taken into account by calculating the pump-induced thermal gradients and by approximating the gain medium as a distributed quadratic lens. Finally, the model was used to offer guidelines about how one of the resonator lenses should be readjusted in order to maintain optimum mode matching as the boundary temperature and pump power are varied.Publication Metadata only Chaos in rotating triatomic clusters(Editions Physique, 1997) Department of Chemistry; Yurtsever, İsmail Ersin; Faculty Member; Department of Chemistry; College of Sciences; 7129Lyapunov exponent distributions of rotating triatomic Lennard-Jones clusters are calculated to analyze the effects of the vibrational and rotational motion on the extent of chaotic behavior. Initial momentum components are assigned to atoms either to rotate the clusters around symmetry axes or to generate random angular momenta. In both cases, it is seen that the initial kinetic energy assigned to vibrational modes is the dominant factor which determines the degree of chaos.Publication Metadata only Cross-cultural industrial and organizational psychology - contributions, past developments, and future directions(Sage, 2000) Department of Psychology; Aycan, Zeynep; Faculty Member; Department of Psychology; College of Social Sciences and Humanities; 5798This article aims at critically evaluating the; theory and scope of cross-cultural industrial and organizational (I/O) research, emphasizing its past and its future. In the theory section, the author discusses the ways sociocultural context influences organizational phenomena. Also discussed are issues such as the level of theory, assumption of linearity, unilateral effect of culture on organizations, conceptualization of culture, and atheoretical nature of research. In the second section, three areas of research, which are underrepresented in cross-cultural I/O literature, are discussed: staffing, performance management, and employee health and safety. It is argued that compared to traditional research topics of cross-cultural I/O psychology (e.g., leadership, motivation, work values, etc.), these topics are more central to the field, more related to improvement of human potential and conditions at work, and better able to guide practices in various cultural contexts.