Digital Commons Network^™

Electrical Properties And Raman Scattering Study Of Single Crystal Cs2nb4o11, Jianjun Liu, E. P. Kharitonova, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, John R. Hardy

Chemistry Faculty Publications

We studied temperature dependence of complex capacitance, impedance, and polarized Raman spectra of single crystal Cs2Nb4O11. First, we observed a sharp-shaped peak at 165 ^oC in the complex capacitance, then found drastic changes in the Raman spectra in the same temperature range. Utilizing the pseudosymmetry search of structure space group, we attributed the observed anomalies to a structural change from the room temperature orthorhombic Pnn2 to another or- thorhombic Imm2. We also measured room temperature polarized Raman spectra in different symmetries of normal vibrations and assigned high wavenumber Raman bands to the internal vibrations of NbO6 octahedra and NbO4 …

A Maximal Chain Approach For Scheduling Tasks In A Multiprocessor Systems, Sachin Pawaskar, Hesham Ali

Computer Science Faculty Proceedings & Presentations

Scheduling dependent tasks is one of the most challenging versions of the scheduling problem in parallel and distributed systems. It is known to be computationally intractable in its general form as well as several restricted cases. As a result, researchers have studied restricted forms of the problem by constraining either the task graph representing the parallel tasks or the computer model. Also, in an attempt to solve the problem in the general case, a number of heuristics have been developed. In this paper, we study the scheduling problem for a fixed number of processors m. In the proposed work, we …

Theoretical Study Of The Magnetic Ordering In Rare-Earth Compounds With Face-Centered-Cubic Structure, Chun-Gang Duan, Renat F. Sabirianov, Jianjun Liu, Wai-Ning Mei, Peter A. Dowben, John R. Hardy

Physics Faculty Publications

We present a detailed theoretical study of the magnetic ordering in heavy rare-earth compounds with a face-centered-cubic structure. In addition to the exchange interactions which are counted up to the third nearest neighbors, the effect of the dipolar interactions and magnetic anisotropic effect are also included in our model Hamiltonian. The interactions parameters are obtained from first-principles band-structure calculations by fitting the total energies of different magnetic configurations to the Heisenberg Model. Thus from utilizing the Monte Carlo simulations, we explained the formation of different magnetic structures in the rare-earth compounds.

L10 Ordered Fept:C Composite Films With (001) Texture, M. L. Yan, Renat F. Sabirianov, Y. F. Xu, X Z. Li, David J. Sellmyer

Physics Faculty Publications

Highly textured (001) FePt:C nanocomposite thin films, deposited directly on thermally oxidized Si wafers, are obtained by multilayer deposition plus subsequent thermal annealing. Nanostructures, crystalline orientations, interactions, and magnetic properties are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), magnetic force microscopy, and magnetic measurements. The formation of the ordered L1₀ phase is confirmed by XRD, and only visible (00 ) peaks indicate a high degree of the (001) texture. TEM observation reveals that FePt grains are embedded in the C matrix and appear to be well isolated.

Bcl2 Translocation Defines A Unique Tumor Subset Within The Germinal Center B-Cell-Like Diffuse Large B-Cell Lymphoma, Javeed Iqbal, Warren G. Sanger, Andreas Rosenwald, Diane L. Pickering, Barbara Dave, Sandeep Dave, Li Xiao, Kahai Cao, Qiuming Zhu, Simon Sherman, Christine P. Hans, Dennis D. Weisenburger, Timothy C. Greiner, Randy D. Gascoyne, German Ott, H. Konrad Müller-Hermelink, Jan Delabie, Rita M. Braziel, Elaine S. Jaffe, Elias Campo, James C. Lynch, Joseph M. Conners, Julie M. Vose, James O. Armitage, Thomas M. Grogan, Louis M. Staudt, Wing C. Chan

Computer Science Faculty Publications

Gene expression profiling of diffuse large B-cell lymphoma (DLBCL) has revealed prognostically important subgroups: germinal center B-cell-like (GCB) DLBCL, activated B cell-like (ABC) DLBCL, and primary mediastinal large B-cell lymphoma. The t(14;18)(q32;q21) has been reported previously to define a unique subset within the GCB-DLBCL. We evaluated for the translocation in 141 cases of DLBCL that were successfully gene expression profiled. Using a dual-probe fluorescence in situ hybridization assay, we detected the t(14;18) in 17% of DLBCLs and in 34% of the GCB subgroup which contained the vast majority of positive cases. In addition, 12 t(14;18)-positive cases detected by polymerase chain …

Simulations Of Ferroelectric Polymer Film Polarization: The Role Of Dipole Interactions, Chun-Gang Duan, Wai-Ning Mei, Jianjun Liu, John R. Hardy, Stephen Ducharme, Peter A. Dowben

Physics Faculty Publications

We present a systematic study of the dipole alignment in the polyvinylidene fluoride (PVDF) films using first-principles total energy calculations. The ground state of a single layer film is a state with all the dipoles lying parallel to the film plane. This can also be explained by a dipole-dipole interaction model. The induced mirror charges on conducting substrates or substrates with a non-negligible dielectric response play an important role in aligning the polarization perpendicular to the film. From fitting the ab initio calculations, we obtain an effective monomer dipole moment of 4.7 x 10⁻³⁰ C m. This corresponds to …

Algorithmic Fusion Of Gene Expression Profiling For Diffuse Large B-Cell Lymphoma Outcome Prediction, Qiuming Zhu, Hongmei Cui, Kahai Cao, Wing C. Chan

Computer Science Faculty Publications

Many different methods and techniques have been investigated for the processing and analysis of microarray gene expression profiling datasets. It is noted that the accuracy and reliability of the results are often dependent on the measurement approaches applied, and no single measurement so far is guaranteed to generate a satisfactory result. In this paper, an algorithmic fusion approach is presented for extracting genes that are predictive to clinical outcomes (survival-fatal) of diffuse large B-cell lymphoma on a set of microarray data for gene expression profiling. The approach integrates a set of measurements from different aspects in terms of the discrepancy …

A Random Boolean Network Model And Deterministic Chaos, Mihaela Teodora Matache, Jack Heidel

Mathematics Faculty Publications

This paper considers a simple Boolean network with N nodes, each node’s state at time t being determined by a certain number of parent nodes, which may vary from one node to another. This is an extension of a model studied by Andrecut and Ali ( [5]) who consider the same number of parents for all nodes. We make use of the same Boolean rule as the authors of [5], provide a generalization of the formula for the probability of finding a node in state 1 at a time t and use simulation methods to generate consecutive states of the …

Sat-Based Answer Set Programming, Enrico Giunchiglia, Yuliya Lierler, Marco Maratea

Computer Science Faculty Proceedings & Presentations

The relation between answer set programming (ASP) and propositional satisfiability (SAT) is at the center of many research papers, partly because of the tremendous performance boost of SAT solvers during last years. Various translations from ASP to SAT are known but the resulting SAT formula either includes many new variables or may have an unpractical size. There are also well known results showing a one-to-one correspondence between the answer sets of a logic program and the models of its completion. Unfortunately, these results only work for specific classes of problems. In this paper we present a SAT-based decision procedure for …

When Are Behaviour Networks Well-Behaved?, Bernhard Nebel, Yuliya Lierler

Computer Science Faculty Proceedings & Presentations

Agents operating in the real world have to deal with a constantly changing and only partially predictable environment and are nevertheless expected to choose reasonable actions quickly. This problem is addressed by a number of action-selection mechanisms. Behaviour networks as proposed by Maes are one such mechanism, which is quite popular. In general, it seems not possible to predict when behaviour networks are well-behaved. However, they perform quite well in the robotic soccer context. In this paper, we analyse the reason for this success by identifying conditions that make behaviour networks goal converging, i.e., force them to reach the goals …

Automatic Compilation Of Protocol Insecurity Problems Into Logic Programming, Alessandro Armondo, Luca Compagna, Yuliya Lierler

Computer Science Faculty Proceedings & Presentations

In this paper we show how protocol insecurity problems expressed in a multi-set rewriting formalism can be automatically translated into logic programming problems. The proposed translation paves the way to the construction of model-checkers for security protocols based on state-of-the-art solvers for logic programs. We have assessed the effectiveness of the approach by running the proposed reduction against a selection of insecurity problems drawn from the Clark & Jacob library of security protocols: by running state-of-the-art solvers against the resulting logic programming problems most of the (known) attacks on the considered protocols are found in a few seconds.

Cmodels-2: Sat-Based Answer Set Solver Enhanced To Non-Tight Programs, Yuliya Lierler, Marco Maratea

Computer Science Faculty Proceedings & Presentations

Answer set programming is a new programming paradigm proposed in [1] and [2], and based on the answer set semantics of Prolog [3]. It is well known that an answer set for a logic program is also a model of the program’s completion [4]. The converse is true when the logic program is “tight” [6, 5]. Lin and Zhao [7] showed that for non-tight programs the models of completion which do not correspond to answer sets can be eliminated by adding to the completion what they called “loop formulas”. Nevertheless, their solver ASSAT¹ has some disadvantages: it can work …

A Sat-Based Polynomial Space Algorithm For Answer Set Programming, Enrico Giunchiglia, Marco Maratea, Yuliya Lierler

Computer Science Faculty Proceedings & Presentations

The relation between answer set programming (ASP) and propositional satisfiability (SAT) is at the center of many research papers, partly because of the tremendous performance boost of SAT solvers during last years. Various translations from ASP to SAT are known but the resulting SAT formula either includes many new variables or may have an unpractical size. There are also well known results showing a one-to-one correspondence between the answer sets of a logic program and the models of its completion. Unfortunately, these results only work for specific classes of problems.

In this paper we present a SAT-Based decision procedure for …

A Fixed Point Theorem For Analytic Functions, Valentin Matache

Mathematics Faculty Publications

We prove that each analytic self-map of the open unit disk which interpolates between certain n-tuples must have a fixed point.

Palindrome-Polynomials With Roots On The Unit Circle, John Konvalina, Valentin Matache

Mathematics Faculty Publications

Given a polynomial f(x) of degree n, let fr(x) denote its reciprocal, i.e., fr(x) = xnf(1=x). If a polynomial is equal to its reciprocal, we call it a palindrome since the coefficients are the same when read backwards or forwards. In this mathematical note we show that palindromes whose coefficients satisfy a certain magnitude-condition must have a root on the unit circle...

Petrography Of Lower Cretaceous Sandstones On Spitsbergen, Harmon D. Maher Jr., Troy Hays, Robert Duncan Shuster, Jeremy Mutrux

Geography and Geology Faculty Publications

The sandstone petrography of sample suites from four sites spanning the Rurikfjellet (Hauterivian) to Carolinefjellet (Aptian–Albian) formations in central Spitsbergen was investigated. The sandstones show a distinct stepwise shift in composition from quartz arenites to sublitharenites and lithic arenites, typically within the upper part of the Helvetiafjellet Formation. This shift is related to the introduction of 10 - 25 % (grain %) plagioclase grains and volcanic lithics, and a notable increase in basement and sedimentary lithics. Quartz grain character also changes, and grain shapes become more varied. The shift is also associated with the transgressive arrival of marine sediments in …

Large Dielectric Constant And Maxwell-Wagner Relaxation In Bi2/3cu3ti4o12, Jianjun Liu, Chun-Gang Duan, Wei-Guo Yin, Wai-Ning Mei, Robert W. Smith, John R. Hardy

Physics Faculty Publications

We studied frequency and temperature dependences of impedance, electric modulus, and dielectric permittivity of Bi2/3Cu3Ti4O12 in the ranges of 10−1–106 Hz and −150–200 °C, respectively. We first observed two electrical responses in the impedance and modulus formalisms. Then we detected a Debye-like relaxation in the permittivity formalism. Most interestingly, we found that the large dielectric constant of Bi2/3Cu3Ti4O12 is independent of the temperature and frequency below 150°C. The results are interpreted in terms of a two-layer model with conducting grains partitioned from each other by poorly conducting grain boundaries. Using this model, we attributed the two electrical responses in impedance …

Electronic Properties Of Nacdf3: A First-Principles Prediction, Chun-Gang Duan, Wai-Ning Mei, Jianjun Liu, Wei-Guo Yin, John R. Hardy, Robert W. Smith, M. J. Mehl, L. L. Boyer

Physics Faculty Publications

Based on first-principles total energy calculations, we predict that NaCdF3 could be formed in a ferroelectric crystal structure. Using a symmetry guided search with structure optimization, we found two ferroelectric structures, nearly degenerate in energy, competing for the ground state: a rhombohedral structure with space group R3c and an orthorhombic structure with space group Pna21. The energies of both structures are '60 meV lower than the sum of those of the constituents, NaF and CdF2, implying chemical stability.

Evaluation Of A Simple Carrier Molecule To Enhance Drug Penetration Of Dermal Layers By Utilizing Multivariate Methods, Structure Property Correlations, And Continuous System Modeling, Ronald Bartzatt

Chemistry Faculty Publications

Nicotinic acid is shown to be comparable to dihydropyridine in its capacity to facilitate penetration of an attached antibacterial drug through dermal layers. Antibacterial drugs examined with nicotinic acid or dihydropyridine carriers were b-lactam antibiotics: methicillin, oxacillin, benzylpenicillin, penicillin F, penicillin dihydro F, propicillin, carbenicillin, penicillin K, penicillin X, and ampicillin. An oxymethyl (-O-CH2-) group is inserted as the linker between the antibiotic and the carrier group. Structure Property Correlations and multivariate methods such as regression analysis, cluster analysis, principal component analysis, discriminate analysis, self-organizing tree algorithm, and factor analysis clearly showed that nicotinic acid performs as an effective carrier …

Superionicity In Na3Po4: A Molecular Dynamics Simulation, Wei-Guo Yin, Jianjun Liu, Chun-Gang Duan, Wai-Ning Mei, Robert W. Smith, John R. Hardy

Physics Faculty Publications

Fast ionic conduction in solid Na₃PO₄ is studied by use of molecular dynamics simulation based on the modified Lu-Hardy approach. We obtain reasonable agreement with experiment for the structural transition and diffusion of the sodium ions. All the sodium ions are found to contribute comparably to the high ionic conductivity. The results of the simulation are discussed in terms of the relative magnitude of the two proposed transport mechanisms: percolation and paddle-wheel. It appears to us that the percolation mechanism dominates the sodium diffusion.