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1999

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Articles 541 - 549 of 549

Full-Text Articles in Physical Sciences and Mathematics

Ordering Due To Disorder In Frustrated Quantum Magnetic Systems, Taner Yildirim Jan 1999

Ordering Due To Disorder In Frustrated Quantum Magnetic Systems, Taner Yildirim

Turkish Journal of Physics

The phenomenon of order by disorder in frustrated magnetic systems is reviewed. Disorder (thermal or quantum fluctuations) may sometimes give rise to long range ordering in systems with frustration, where one must often consider the selection among classically degenerate ground states which are not equivalent by any symmetry. The lowest order effects of quantum fluctuations in such frustrated systems usually resolves the continues degeneracy of the ground state manifold into discrete Ising--type degeneracy. A unique ground state selection out of this Ising degenerate manifold then occurs due to higher order effects of quantum fluctuations. For systems such as face-centered cubic …

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The Renormalization-Group Microscope: The Local Statistical Mechanics Of Heterogeneous Systems, Dicle Yeşi̇lleten, A. Nihat Berker Jan 1999

The Renormalization-Group Microscope: The Local Statistical Mechanics Of Heterogeneous Systems, Dicle Yeşi̇lleten, A. Nihat Berker

Turkish Journal of Physics

Renormalization-group theory is developed to yield all local microscopic thermodynamic densities in heterogeneous systems. Local energy densities and local magnetizations are thus obtained for random-bond systems, random-field systems, and spin-glasses, in two and three dimensions. Different order-disorder mechanisms in these diverse systems, such as chaotic ordering and domain-wall melting, become quantitatively evident.

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Experimental Determination Of \Beta And \Gamma Critical Exponents In The Sol-Gel Phase Transition By Using Steady-State Fluorescence Technique, Y. Yilmaz, Ö. Pekcan Jan 1999

Experimental Determination Of \Beta And \Gamma Critical Exponents In The Sol-Gel Phase Transition By Using Steady-State Fluorescence Technique, Y. Yilmaz, Ö. Pekcan

Turkish Journal of Physics

The gelation of methyl methacrylate and ethylene glycol dimethacrylate was studied using the steady-state fluorescence technique. Samples with various crosslinker densities were prepared and sol-gel phase transitions were observed at various temperatures. Percolation theory was employed to interpret the results. For all samples the gel fraction and the average cluster size exponents, \beta and \gamma, were measured and found to be around 0.42 and 1.7 respectively. These values show excellent agreement with theoretical and simulation results.

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Studies On Extremal Segments In Random Sequences, Deniz Ertaş, Yacov Kantor Jan 1999

Studies On Extremal Segments In Random Sequences, Deniz Ertaş, Yacov Kantor

Turkish Journal of Physics

We review our main findings on the size distribution of the largest neutral segments in a sequence of N randomly charged monomers. Upon mapping to one--dimensional random walks (RWs), this corresponds to finding the probability distribution for the size L of the largest segment that returns to its starting position in an N--step RW. Using analytical, exact enumeration, and Monte Carlo methods, we reveal the complex structure of the probability distribution in the large N limit. In particular, the size of the longest neutral segment has a distribution with a square-root singularity at \ell\equiv L/N = 1, an essential singularity …

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Integrating Multimedia Techniques Into Cs Pedagogy, Sandra Honda, Richard Jou, Ahmad Nasri, Anne-Louise Radimsky, Bon K. Sy Jan 1999

Integrating Multimedia Techniques Into Cs Pedagogy, Sandra Honda, Richard Jou, Ahmad Nasri, Anne-Louise Radimsky, Bon K. Sy

School of Computer Science & Engineering Faculty Publications

Through its grants, the National Science Foundation sponsors workshops that inform faculty of current topics in Computer Science. Such a workshop, entitled, "Developing Multimedia-based Interactive Laboratory Modules for Computer Science", was given July 27 -August 6, 1998, at Illinois State University in Normal, Illinois. Each participant was expected to design and implement a small part of a laboratory module. This paper describes what some of the faculty members who participated in the workshop have done with the knowledge obtained from the workshop.

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Seiberg-Witten Invariants Of Mapping Tori,Symplectic Fixed Points, And Lefschetz Numbers, Dietmar A. Salamon Jan 1999

Seiberg-Witten Invariants Of Mapping Tori,Symplectic Fixed Points, And Lefschetz Numbers, Dietmar A. Salamon

Turkish Journal of Mathematics

No abstract provided.

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Virtual Neighborhoods And Pseudo-Holomorphic Curves, Yongbin Ruan Jan 1999

Virtual Neighborhoods And Pseudo-Holomorphic Curves, Yongbin Ruan

Turkish Journal of Mathematics

No abstract provided.

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Normal Subgroups And Elements Of H^{'}(\Lambda_Q), İsmai̇l Naci̇ Cangül Jan 1999

Normal Subgroups And Elements Of H^{'}(\Lambda_Q), İsmai̇l Naci̇ Cangül

Turkish Journal of Mathematics

In this study, we consider the normal subgroups of H^{'}(\lambda_q), where H(\lambda_q) denotes the Hecke groups. After recalling some results from [2], particularly on the group structure and on the relations with the power subgroups of H(\lambda_q), the even subgroup H_e(\lambda_q) of H(\lambda_q) is discussed. It is shown that H^{'}(\lambda_q) is a normal subgroup of H_e(\lambda_q) with index q. For this reason each subgroup of H^{'}(\lambda_q) consists of only even elements. H^{''}(\lambda_q) is also considered and it is concluded that it is the normal subgroup of H^{'}(\lambda_q) generated by all commutators of the elements of H^{'}(\lambda_q). Using the Kurosh subgroup …

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Univalent Harmonic Mappings Onto Half Planes, Meti̇n Öztürk Jan 1999

Univalent Harmonic Mappings Onto Half Planes, Meti̇n Öztürk

Turkish Journal of Mathematics

We consider the class S_H(D,\Omega ) of complex functions f which are univalent, harmonic, sense preserving on a simple connected domain D\neq {\Bbb C} \ containing the origin, satisfy f(0)=a_0, f_{\bar z}(0)=0a,\ a\in {\Bbb R}\}. In particularly, we describe the closure \overline{S_H(D,\Omega )} of S_H(D,\Omega ) and characterize its extreme points, as well as sharp estimates for coefficients and distortion theorems.

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