bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-armed, TEMPO-functionalized unimolecular initiators for starburst dendrimer synthesis via stable free radical polymerization. 1. Tri azo-functionalized unimer
Authors: Abdallah Dalia , Ghani Mohmad Asri Abd , Cunningham Michael F , Kazmaier Peter M , Keoshkerian Barkev , Buncel Erwin
Published: November 2004

The synthesis of azobenzene-functionalized multi-armed unimolecular initiators or "unimers" that can be polymerized using styrene or styrenic derivatives via TEMPO (2,2,6,6-tetramethylpiperidenyl-1-oxyl) mediated stable free radical polymerization (SFRP) is described. The unimers are composed of an azobenzene-functionalized core and a TEMPO-modified unit. Homopolymers and copolymers of styrene and acetoxystyrene were synthesized using the mono-and trifunctionalized unimers as initiators under bulk conditions with average molecular weights and polydispersities reported. The studies lay the groundwork for further investigations involving SFRP towards building a light harvesting system by introducing chromophores onto the polymer chains for capturing light and thence transferring it to the azobenzene core.Key words: azo-functionalized unimolecular initiator, stable free radical polymerization, starburst dendrimer.
Fluorine chemistry. Part 2. Synthesis and characterization of 2H-heptafluoropropane (HFC-227ea)
Authors: Bhadury Pinaki S , Singh Sapna , Sharma Mamta , Malhotra Ramesh C , Sekhar Krishnamurthy
Published: November 2004

A facile method has been developed for the synthesis and characterization of volatile 1,1,1,2,3,3,3- heptafluoropropane (HFC-227ea), a potential non-ozone depleting hydrofluorocarbon substitute for Halon 1301 (CF3Br). The method involves hydrofluorination of hexafluoropropene using in situ generated onium bifluoride obtained from the decomposition of anhydrous tetrabutylammonium fluoride. The reagent acts as an excellent equivalent to hydrogen fluoride and permits the use of normal glassware.Key words: 2H-heptafluoropropane, hydrofluorocarbon, hexafluoropropene, tetrabutylammonium fluoride, hydrofluorination.
Network Orientation
Authors: TEL GERARD
Published: November 2004

This paper analyses how the symmetry of a processor network influences the existence of a solution for the network orientation problem. The orientation of hypercubes and tori is the problem of assigning labels to each link of each processor, in such a way that a sense of direction is given to the network. In this paper the problem of network orientation for these two topologies is studied under the assumption that the network contains a single leader, under the assumption that the processors possess unique identities, and under the assumption that the network is anonymous. The distinction between these three models is considered fundamental in distributed computing.

It is shown that orientations can be computed by deterministic algorithms only when either a leader or unique identities are available. Orientations can be computed for anonymous networks by randomized algorithms, but only when the number of processors is known. When the number of processors is not known, even randomized algorithms cannot compute orientations for anonymous processor networks.

Lower bounds on the message complexity of orientation and algorithms achieving these bounds are given.
DETERMINATION OF PHYSICAL QUANTITIES FOR PIXE BY MEANS OF PIXE 1: ABSORPTION CURVE
Authors: SERA K. , FUTATSUGAWA S. , HATAKEYAMA S. , SAITOU S.
Published: November 2004

A new method has been developed to determine absorption curves which are needed to derive quantitative values in PIXE analysis. In this method two spectra obtained with absorbers of different thickness are divided by each other after background subtraction and the absorption curve can be obtained immediately. Absorption curves for a 50 and a 200 µm-thick Mylar films and that for a Cr foil of 2500 µg/cm2 were determined experimentally. These curves are in good agreement with the absorption values derived from peak areas of characteristic x-rays. This method enables one to obtain absorption curves for any kind of absorber accurately and quickly.
DETERMINATION OF PHYSICAL QUANTITIES FOR PIXE BY MEANS OF PIXE 2: EFFICIENCY CURVE
Authors: SERA K. , FUTATSUGAWA S. , MATSUDA K.
Published: November 2004

A new method has been developed for determining detection efficiency of a Si(Li) detector, which is one of the most important quantities in PIXE analysis. In this method, targets prepared by smashing crystals of several chemical compounds into fine pieces and by sprinkling them onto a thin polypropylene film are measured in same experimental condition as in PIXE analysis, and relative efficiency curves are obtained for two Si(Li) detectors. These results are compared with those from theoretical calculations. New efficiency curves are obtained by regarding thickness of the Be window, the Si dead layer, the gold contact and ice layer as variable parameters and practical thicknesses of them are estimated. It is found that these efficiency curves give quantitatively fairly accurate values when they are used for data analysis from NIST bovine liver even in cases of Na and Mg.
HBTs FOR MICROWAVE POWER APPLICATIONS
Authors: BAYRAKTAROGLU BURHAN , HIGGINS J. AIDEN
Published: November 2004

The status of the microwave power HBT is reviewed. The rapid progress made in this technology is fueled by the need for high performance transmitter amplifiers, advanced military systems and supported by the favorable electronic properties of the device. A survey of the device design and fabrication techniques indicates that the technology has not yet reached its limit; further advances are possible and performance improvements will continue. The power and efficiency of GaAs HBTs are now competitive with the most advanced microwave devices in the 1–20 GHz range.
NOISE CHARACTERISTICS OF InP-BASED HETEROSTRUCTURE BIPOLAR TRANSISTORS
Authors: CHEN Y.K. , HUMPHREY D.A. , FAN L. , HAMM R.A. , SIVCO D. , CHO A.Y. , TATE A.
Published: November 2004

The noise characteristics of InP -based heterostructure bipolar transistors (HBTs) are studied from low frequency to microwave frequency. The nonequilibrium minority carrier transport in the thin base region is very effective in reducing the 1/f noise current at low frequency as well as reducing the uncorrelated shot noise current at high frequency. Experimentally, a very low 1/f noise corner frequency of 1.55 kHz is obtained in AlInAs/InGaAs HBTs with a 70 nm-thick base. This is the lowest 1/f corner frequency amongst any compound semiconductor devices reported to date. Minimum noise figures of 0.46 dB, 2.0 dB and 3.33 dB are also demonstrated at 2 GHz, 10 GHz and 18 GHz, respectively, with InP/InGaAs HBTs with a 35 nm-thick base and 3.5×3.5 μ m 2 emitter.
ON THE ALIGNMENT PROBLEM
Authors: DARTE ALAIN , ROBERT YVES
Published: November 2004

This paper deals with the problem of aligning data and computations when mapping uniform or affine loop nests onto SPMD distributed memory parallel computers. For affine loop nests we formulate the problem by introducing the communication graph, which can be viewed as the counterpart for the mapping problem of the dependence graph for scheduling. We illustrate the approach with several examples to show the difficulty of the problem. In the simplest case, that of perfect loop nests with uniform dependences, we show that minimizing the number of communications is NP-complete, although we are able to derive a good alignment heuristic in most practical cases.
ON THE GENERATING FUNCTIONAL FOR PROPER VERTICES OF LOCAL COMPOSITE OPERATORS IN THE GAUGED NAMBU-JONA-LASINIO MODEL
Authors: MIRANSKY V.A.
Published: November 2004

The generating functional (effective action) for proper vertices of local composite operators [Formula: see text] and [Formula: see text] in the gauged Nambu-Jona-Lasinio model is considered. We show that, unlike QCD-like dynamics, it is a well-defined object in the continuum limit (at the critical line of the model). The effective action is applied for studying spinless bound states in the model. In particular, we show that the bound states disappear with cutoff Λ→∞ in the symmetric phase, near the part of the critical line with α=αc=π/3. A mass relation for scalar bound states is derived in the nonsymmetric phase, near this part of the critical line.
ON THE CHIRAL RINGS IN N=2 AND N=4 SUPERCONFORMAL ALGEBRAS
Authors: GÜNAYDIN MURAT
Published: November 2004

We study the chiral primary rings of N=2 and N=4 superconformal algebras (SCA’s) constructed over triple systems. The chiral primary states of N=2 SCA’s realized over Hermitian Jordan triple systems are given. Their coset spaces G/H are Hermitian-symmetric and can be compact or noncompact. In the noncompact case under the requirement of unitarity of the representations of G, we find an infinite discrete set of chiral primary states associated with the holomorphic discrete series representations of G and their analytic continuation. A further requirement that the corresponding N=2 module be unitary truncates this infinite set to a finite subset. There are no chiral primary states associated with the other unitary representations of noncompact groups. Remarkably, the only noncompact groups G that admit holomorphic discrete series unitary representations are such that their quotients G/H with their maximal compact subgroups H are Hermitian-symmetric. The chiral primary states of N=2 SCA’s constructed over the Freudenthal triple systems are also studied. These algebras have the special property that they admit an extension to N=4 superconformal algebras with the gauge group SU(2) ⊗ SU(2) ⊗ U(1). We then generalize the concept of chiral rings to these maximal N=4 superconformal algebras. We find four different rings associated with each sector (left- or right-moving). Inclusion of both sectors gives 16 different rings. We also show that our analysis yields all the possible rings of N=4 SCA’s.
MESONIC EXCITATIONS IN THE LINEAR SIGMA MODEL
Authors: MALHEIRO M. , NEMES M.C. , NIELSEN M. , da PROVIDÊNCIA J.
Published: November 2004

A semiclassical version of the linear sigma model is studied in a variational approach. Specifically we study the bosonic spectroscopy for both bound states and resonances. We give a quantitative description of the pion and its two observed resonances.
ONE-DIMENSIONAL STRING THEORY WITH VORTICES AS THE UPSIDE-DOWN MATRIX OSCILLATOR
Authors: BOULATOV DMITRI , KAZAKOV VLADIMIR
Published: November 2004

Matrix quantum mechanics at a finite temperature is considered, which is equivalent to the one-dimensional compactified string field theory with vortex excitations. It is explicitly demonstrated that states transforming under nontrivial U(N) representations describe different vortex-antivortex configurations. For example, for the adjoint representation, corresponding Feynman graphs always contain two big loops wrapping around the compactified t space, which corresponds to the vortex–antivortex pair. The technique is developed to calculate the partition functions in given representations for the standard matrix oscillator, and then the procedure of their analytical continuation to the upside-down case is worked out. This procedure enables us to obtain the partition function in the presence of the vortex–antivortex pair in the double scaling limit. Using this result, we calculate the critical temperature for the Berezinski-Kosterlitz–Thouless phase transition. A possible generalization of our technique for the D+1 dimensional matrix model is sketched out.
PARTON DISTRIBUTIONS IN THE PHOTON
Authors: ABRAMOWICZ H. , CHARCHUŁA K. , KRAWCZYK M. , LEVY A. , MAOR U.
Published: November 2004

The theoretical and experimental situation related to the photon structure function is reviewed. The existing parton distributions of the resolved photon are discussed, in view of their importance for the study of various processes at HERA.
THE COMPLETE SUPERSPACE ACTION OF CHIRAL D=10, N=2 SUPERGRAVITY
Authors: CASTELLANI LEONARDO , PESANDO IGOR
Published: November 2004

We construct the complete superspace action ℒ of chiral D=10, N=2 supergravity. The self-duality condition on the field strength Fa1 - a5 is derived as an equation of motion in superspace. The space-time restriction of ℒ is not supersymmetric, since the self-duality condition does not follow from the space-time variational equations. However, supersymmetry can be restored via the introduction of a Lagrange multiplier term.
NONLOCAL CURRENTS IN THE MASSIVE THIRRING MODEL
Authors: KAUL R.K. , RAJARAMAN R.
Published: November 2004

We derive nonlocal conserved currents in the massive Thirring model, treating the model as a perturbation on a conformal field theory. These currents carry fermion number two, and reduce to polynomials in the Fermi field for the special values of the Thirring coupling g=n/2.
SU(N)1 CORRELATION FUNCTIONS ON HIGHER-GENUS RIEMANN SURFACES
Authors: ALIMOHAMMADI M. , ARFAEI H.
Published: November 2004

Using factorization properties of Green functions under nonzero homology pinching, and OPE of the SU (N)1 primary fields, we find the multipoint correlators of primary fields and a class of (Kac–Moody) descendant fields of SU (N)1 WZNW models on higher-genus Riemann surfaces. We will also justify our results with the help of some selection rules.
DIRAC'S QUANTIZATION OF THE CHIRAL SCHWINGER MODEL — PART I
Authors: SARADZHEV FUAD M.
Published: November 2004

We consider the chiral Schwinger model in order to clarify certain points concerning its nonlocal quantum theory constructed in Ref. 1 in the framework of the canonical quantization scheme. In particular, we derive the transition rules between the nonlocal quantum theory of the model and the standard classical one. We obtain the spectrum of the quantum Hamiltonian on the physical Hilbert space. Finally, we show that the nonlocality does not violate microcausality.
A QUADRATIC DEFORMATION OF THE HEISENBERG–WEYL AND QUANTUM OSCILLATOR ENVELOPING ALGEBRAS
Authors: PETERSEN JENS U. H.
Published: November 2004

A new two-parameter quadratic deformation of the quantum oscillator algebra and its one-parameter deformed Heisenberg subalgebra are considered. An infinite-dimensional Fock module representation is presented, which at roots of unity contains singular vectors and so is reducible to a finite-dimensional representation. The semicyclic, nilpotent and unitary representations are discussed. Witten's deformation of sl 2 and some deformed infinite-dimensional algebras are constructed from the 1d Heisenberg algebra generators. The deformation of the centerless Virasoro algebra at roots of unity is mentioned. Finally the SL q(2) symmetry of the deformed Heisenberg algebra is explicitly constructed.
MATRIX MODELS AND ONE-DIMENSIONAL OPEN STRING THEORY
Authors: MINAHAN JOSEPH A.
Published: November 2004

We propose a random matrix model as a representation for D = 1 open strings. We show that the model with one flavor of boundary fields is equivalent to N fermions with spin in a central potential that also includes a long-range ferromagnetic interaction between the fermions that falls off as 1/(rij)2. We also generalize this theory to contain an arbitrary number of flavors. For an appropriate choice of the matrix model potential the ground state of the system can be found. Using this potential, we calculate the free energy in the double scaling limit and show that the free energy expansion has the expected form for a theory of open and closed strings if the boundary field mass and couplings have a logarithmic divergence. We then examine the critical properties of this theory and show that the length of the boundary around a hole remains finite, even near the critical point. We also argue that unlike critical string theory or a D = 0 theory, the open string coupling constant is a free parameter.
MASS BOUNDS ON THE EXTRA NEUTRAL VECTOR BOSONS AT FUTURE e+e− COLLIDERS WITH POLARIZED BEAMS
Authors: LIKHODED A.A. , SHEVLYAGIN M.V. , YUSHCHENKO O.P.
Published: November 2004

After the example of the extended electroweak models, which predict the existence of the heavy neutral vector boson Z′, we discuss, for the e+e− linear colliders of the new generation, the possibilities of searching for the extra boson effects provided that various configurations of the beam polarizations will be available. For the most popular models [E6-superstring-inspired, LR- and Y(YL)-composite models] we show that realization of the specific beam polarizations can substantially enhance the experiment sensitivity to the Z′ signal in comparison with the case of the unpolarized beams.
COSET CONSTRUCTION OF MINIMAL MODELS
Authors: LASHKEVICH M. YU.
Published: November 2004

The usual coset construction SU (2)k× SU (2)l/ SU (2)k+l of Wess-Zumino conformal field theory is presented as a coset construction of minimal models. This new construction can be defined rigorously and allows one to calculate easily correlation functions of a number of primary fields.
MASSLESS FLOWS II: THE EXACT S-MATRIX APPROACH
Authors: FENDLEY P. , SALEUR H. , ZAMOLODCHIKOV AL. B.
Published: November 2004

We study the spectrum, the massless S matrices and the ground-state energy of the flows between successive minimal models of conformal field theory, and within the sine-Gordon model with imaginary coefficient of the cosine term (related to the minimal models by “truncation”).

For the minimal models, we find exact S matrices which describe the scattering of massless kinks, and show using the thermodynamic Bethe ansatz that the resulting non-perturbative c function (defined by the Casimir energy on a cylinder) flows appropriately between the two theories, as conjectured earlier.

For the nonunitary sine-Gordon model, we find unusual behavior. For the range of couplings we can study analytically, the natural S matrix deduced from the minimal one by “undoing” the quantum-group truncation does not reproduce the proper c function with the TBA. It does, however, describe the correct properties of the model in a magnetic field.
OPTIMAL PROTOTYPE FUNCTIONS OF FEATURES FOR ONLINE SIGNATURE VERIFICATION
Authors: MARTÍNEZ ROMO JULIO CESAR , ALCÁNTARA SILVA ROGELIO
Published: November 2004

It is well known that the approach of functions of time to represent the dynamic and static characteristics of signatures usually outperforms the approaches based on parameters; in addition to this result, we propose here that the model or prototype function of the discriminant features of the signatures should be created considering the signature verification problem as a bi-objective optimization problem in which the false acceptance and false rejection rates are minimized simultaneously; to accomplish these goals, a discrete space of solutions is searched by a genetic algorithm, and a continuous space of solutions is searched by a modified gradient method, both spaces containing candidate prototype functions and the one that best meets some optimization criteria is first chosen as the optimal prototype function and then improved. Given that creating the prototype functions of features is just one of the earlier steps of a signature verification system, we also propose here a scheme of signature verification algorithm with intelligent classification. Our approach was tested in the context of random and highly skilled forgeries, with error rates below 0.1% over 7,300 verifications. Our database consisted of 1,762 exemplars, containing genuine signatures and skilled forgeries from 36 persons. Comparison to other methods of making prototype functions of features is shown.
FROM EQUATIONS TO HARDWARE: TOWARDS THE SYSTEMATIC MAPPING OF ALGORITHMS ONTO PARALLEL ARCHITECTURES
Authors: FRISON PATRICE , CHAROT FRANÇOIS , GAUTRIN ERIC , LAVENIER DOMINIQUE , QUINTON PATRICE , RAIMBAULT FRÉDÉRIC , WAGNER CHARLES
Published: November 2004

Advances in VLSI technology make it possible to realize systems of very high complexity in a small volume of hardware using integration. In many application fields, it is necessary to implement certain algorithms, or even complete information processing systems, directly in silicon. Application domains which are likely to benefit are in the fields of signal processing and scientific computing.

In this paper, we consider several steps which we believe to be essential in the design path of a special purpose architecture, and we present methodologies for achieving design requirements. These solutions are based on experience gathered in the Parallel VLSI Architecture group of IRISA.
THREE-DIMENSIONAL SEQUENTIAL/PARALLEL UNIVERSAL ARRAY GRAMMARS FOR POLYHEDRAL OBJECT PATTERN ANALYSIS
Authors: WANG P.S.P.
Published: November 2004

We introduce a sequential/parallel parsing algorithm for analyzing 3-dimensional polyhedral objects represented by 3-d universal array grammars. The mechanism serves as a compromise between purely sequential methods, which normally take too much time, and purely parallel methods, which take too much hardware for large digital arrays. Several examples of 3-d polyhedral objects of various shapes and their corresponding parsing sequences are illustrated. Future research topics are discussed.
AUTOMATIC SIGNATURE VERIFICATION: THE STATE OF THE ART—1989–1993
Authors: LECLERC FRANCK , PLAMONDON RÉJEAN
Published: November 2004

This paper is a follow up to an article published in 1989 by R. Plamondon and G. Lorette on the state of the art in automatic signature verification and writer identification. It summarizes the activity from year 1989 to 1993 in automatic signature verification. For this purpose, we report on the different projects dealing with dynamic, static and neural network approaches. In each section, a brief description of the major investigations is given.
A ROBUST STROKE EXTRACTION METHOD FOR HANDWRITTEN CHINESE CHARACTERS
Authors: CHANG HONG-DE , WANG JHING-FA
Published: November 2004

The stroke analysis method is an effective approach for handwritten Chinese character recognition. But as we know, it is very difficult to accurately extract the strokes. In this paper, a robust stroke extraction method is proposed. First, smoothing and thinning processes are applied to smooth the shape and to obtain the skeleton of the observed character. Then the end point, internal point and fork point are detected by calculating their own crossing numbers while the corner points are determined by a knowledge-based iterative method. Virtual-end-points are introduced for separating a stroke into a certain number of line segments without losing the connection relations among them. By representing each line segment as a vertex and the connection relation of two segments as an edge, the observed character can be represented by an attributed graph. Finally, a stroke extraction procedure is proposed to extract the strokes from the global structures of the character. After each stroke of a character is extracted, the cross points can also be determined. Experimental results have shown that the proposed method is more effective than the other methods.3,5−6
SEMI-ACTIVE CONTROL FOR VIBRATION SUPPRESSION IN A SYSTEM SUBJECTED TO UNKNOWN DISTURBANCES
Authors: LEITMANN G.
Published: November 2004

With the advent of materials, such as electrorheological fluids, whose material properties can be altered rapidly by means of external stimuli, employing such materials as actuators for the controlled attenuation of undesirable vibrations is now possible. Such control schemes are dubbed semi-active in that they attenuate vibrations whether applied actively or passively. We investigate various such control schemes, allowing for both separate and joint control of the stiffness and damping characteristics of the material. Simulation results are given for the case of an electrorheological fluid.
SOFTWARE PROCESS MONITORING MECHANISMS IN OIKOS
Authors: MONTANGERO C. , SCARSELLI F.
Published: November 2004

Collecting information about the performance of a software process is a necessary step for the assessment of the process quality. Oikos is an environment for the definition and the enactment of software process models. This paper presents the Oikos approach to history recording. We define the events that compose the histories and explain how the events to be monitored can be selected. Finally, we discuss the implementation of the recording mechanism.
AUTOMATIC STRUCTURES AND BOUNDARIES FOR GRAPHS OF GROUPS
Authors: NEUMANN WALTER D. , SHAPIRO MICHAEL
Published: November 2004

We study the synchronous and asynchronous automatic structures on the fundamental group of a graph of groups in which each edge group is finite. Up to a natural equivalence relation, the set of biautomatic structures on such a graph product bijects to the product of the sets of biautomatic structures on the vertex groups. The set of automatic structures is much richer. Indeed, it is dense in the infinite product of the sets of automatic structures of all conjugates of the vertex groups. We classify these structures by a class of labelled graphs which “mimic” the underlying graph of the graph of groups. Analogous statements hold for asynchronous automatic structures. We also discuss the boundaries of these structures.
SBS-PHASE CONJUGATION FOR THERMAL LENS COMPENSATION IN 100 W AVERAGE POWER SOLID-STATE LASERS
Authors: EICHLER H.J. , HAASE A. , MENZEL R.
Published: November 2004

The thermal lensing effect in high-average power Nd:YAG-laser amplifiers is compensated by stimulated Brillouin scattering in CS 2. Nearly diffraction limited laser beams with average powers above 100 Watts were obtained. The system emitted bursts of 10 to 30 pulses with 40 ns width. The bursts have a repetition rate of 100 Hz and a duration of 100 µs. The beam quality degrades by depolarization effects at the highest pump and output powers. This degradation is avoided using polarization preserving Nd:YALO-laser crystals.
AlGaAs BELOW HALF BANDGAP: THE SILICON OF NONLINEAR OPTICAL MATERIALS
Authors: STEGEMAN G.I. , VILLENEUVE A. , KANG J. , AITCHISON J.S. , IRONSIDE C.N. , AL-HEMYARI K. , YANG C.C. , LIN C.-H. , LIN H.-H. , KENNEDY G.T. , GRANT R.S. , SIBBETT W.
Published: November 2004

Very few nonlinear optical materials are actually useful for high throughput all-optical devices. However, AlGaAs does satisfy all of the nonlinear optical figures of merit when used with photons of energy less than one half the semiconductor bandgap. Here we review our measurements of the pertinent nonlinear coefficients in waveguides and various device applications to all-optical switching in the communications band around 1550 nm.
THE OK BDI ARCHITECTURE
Authors: KUMAR DEEPAK , SHAPIRO S.C.
Published: November 2004

The design of a belief-desire-intention (BDI) architecture is presented. The architecture is defined using a unified object-based knowledge representation formalism, called the OK formalism, and a unified reasoning and acting module, called the OK rational engine. Together they form the OK BDI architecture for modeling rational agents endowed with beliefs, desires, and intentions.
AN OBJECT-ORIENTED RULE EVALUATION SCHEME FOR LOGICAL DATABASES IN MASSIVELY PARALLEL ENVIRONMENT
Authors: SHEU P.C.-Y. , LEE W.S.
Published: November 2004

This paper extends an object-oriented approach to query processing in a deductive database with the consideration of deductive rules. In the object-oriented approach, each deductive rule and fact is represented as an active object, which acts with its own dedicated control sequences according to its functionality. All operations in objects are proceeded asynchronously. Since no object has global knowledge about the database, cooperation among objects is necessary in answering a query. While most of the conventional search strategies focus on some parts of the AND/OR tree expanded by a query at a time, the object-oriented approach can search down the AND/OR tree with a breadth-first strategy in parallel. As a result, all parts of the tree can be considered globally so that queries do not have to be evaluated in a tuple-by-tuple, operation-by-operation fashion; and the need of maintaining temporary relations can be eliminated.
THE ROLE OF COMMITMENT IN COOPERATIVE NEGOTIATION
Authors: SEN SANDIP , DURFEE EDMUND H.
Published: November 2004

Cooperative information agents need mechanisms that enable them to work together effectively while solving common problems. We investigate the use of commitment by agents to proposed actions as a mechanism that allow agents to work concurrently on interdependent problems. Judicious use of commitment can not only increase the throughput of cooperative information systems, but also allow them to deal flexibly with dynamically changing environments. We use the domain of distributed scheduling to demonstrate that static commitment strategies are ineffective. Results from simulated experiments are used to identify the environmental features on which an adaptive commitment strategy should be predicated.
MODEL BASED INFORMATION ACCESS
Authors: JAGANATHAN V. , KARINTHI R. , ALMASI G. , SOBOLEWSKI M.
Published: November 2004

The engineering data of a large enterprise is typically distributed over a wide area and archived in a variety of databases and file systems. Access to such information is crucial to a team member, particularly in a concurrent engineering setting. However, this is not easy, because (1) a model of the relevant information is not available, and (2) there is no simple way to access the information without being knowledgeable about various computer data formats, file systems, and networks. We have developed a system called the Information Sharing System (ISS) to enable access to diverse and distributed information within a corporation. Such data could be stored in different repositories such as databases and file systems including those that contain multiple media. Our paper describes the methodology of the ISS, the details of the implementation and extensions planned for the future.
DECISION SUPPORT THROUGH FACILITATING THE EXCHANGE OF EXPERIENCES IN A DISTRIBUTED ENVIRONMENT
Authors: HOFBAUER THOMAS H. , WOO CARSON C. , MARTENS CLARENCE D.
Published: November 2004

This paper suggests a new perspective for Decision Support Systems (DSS) that is guided by the dominant role of experience in decision making. This perspective is motivated by evidence from cognitive research supporting the view that organizational problem solvers rely to a large extent on episodic knowledge gained from similar problem solving experiences. In addition, research indicates that organizational workers tend to cooperate and seek others' experiences, especially as task domains become more complex and relevant knowledge becomes more sparse. To this end we propose a decision support architecture using a combined approach of Case-Based Reasoning and Analogical Reasoning, which utilizes previous decision making results to aid in current problem solving activities, and distributed case management, which facilitates the exchange of computer-mediated experiences among organizational workers. A prototype implementation that demonstrates the feasibility of this approach is also described.
MANAGING READ-ONLY DATA ON ARBITRARY NETWORKS WITH FULLY DISTRIBUTED CACHING
Authors: FLATER DAVID W. , YESHA YELENA
Published: November 2004

In a large information system, the amount of cache space available to store read-only replicas of data may be limited. Since acquiring these data from their sources may be an expensive and time-consuming operation, it is essential to make efficient use of the available cache space. This cache space may be unevenly distributed over a large number of loosely coupled sites. An intelligent caching strategy is needed to insure that replicas are created often enough that they can be inexpensively reached when necessary, but not so often that important data are forced out to make room. We present such a strategy, which we have developed for use in ALIBI, a networked resource discovery and information retrieval system. The TCF Strategy, as it is called, allows individual sites to adjust their level of cache turnover to provide better overall performance. This novel approach could no doubt be beneficially applied in other distributed systems which use caching. We include discussion and simulation results supporting the efficiency of the TCF Strategy.
A MATHEMATICAL MODEL OF TUMOR GROWTH WITH SPATIALLY DECREASING DIFFUSION COEFFICIENT OF MITOTIC INHIBITOR
Authors: CHATTOPADHYAY J. , TAPASWI P.K.
Published: November 2004

Intercellular diffusion of mitosis inhibiting factors, maintained by proper intercellular contact, is one of the means of transferring “positional information”—a message to peripheral cells of a growing normal tissue instructing them where (at what size of the tissue) to stop their further proliferation by mitotic cell division. This property is commonly known as “contact cell inhibition of mitosis” in biology. In a growing tumor tissue, this regulatory mechanism is absent and as a result, peripheral cells of a tumor tissue, being devoid of any “positional information”, go on dividing successively, increasing the size of the tumor (uncontrolled growth). In this paper, the above idea has been captured in a reaction-diffusion model of tumor tissue growth with a spatially decreasing diffusion coefficient, D(r), of the mitotic inhibitor. This model merely provides an alternative explanation of certain observations on normal and tumor tissue growth. The solutions of the simple model (with (i) D=constant for normal tissue growth and (ii) D=D(r) for tumor tissue growth), discussed in this paper, quite reasonably agree with the characteristic patterns of normal and tumor tissue growth.
ENRICHED INTERVAL BILATTICES AND PARTIAL MANY-VALUED LOGICS: AN APPROACH TO DEAL WITH GRADED TRUTH AND IMPRECISION
Authors: ESTEVA FRANCESC , GARCIA-CALVÉS PERE , GODO LLUÍS
Published: November 2004

Within the many-valued approach for approximate reasoning, the aim of this paper is two-fold. First, to extend truth-values lattices to cope with the imprecision due to possible incompleteness of the available information. This is done by considering two bilattices of truth-value intervals corresponding to the so-called weak and strong truth orderings. Based on the use of interval bilattices, the second aim is to introduce what we call partial many-valued logics. The (partial) models of such logics may assign intervals of truth-values to formulas, and so they stand for representations of incomplete states of knowledge. Finally, the relation between partial and complete semantical entailment is studied, and it is provedtheir equivalence for a family of formulas, including the so-called free well formed formulas.
SOME ELEMENTS OF THE THEORY OF QUALITATIVE POSSIBILISTIC NETWORKS
Authors: PARSONS SIMON
Published: November 2004

This paper presents some results concerning the qualitative behaviour of possibilistic networks. The behaviour of singly connected networks is analysed, providing the foundations for qualitative reasoning about changes in possibility values in both predictive and evidential directions. The problems inherent in handling multiply connected networks are also discussed, and a possible solution is proposed. The behaviour of qualitative possibilistic networks is compared to qualitative probabilistic networks, and an example of the kind of reasoning that is permitted by the use of these networks is provided.
A RULE-BASED METHOD TO CALCULATE THE WIDEST SOLUTION SETS OF A MAX-MIN FUZZY RELATIONAL EQUATION
Authors: ARNOULD THIERRY , TANO SHUN'ICHI
Published: November 2004

In this paper, we propose a new rule-based method to determine exactly all the widest solution sets of a max-min fuzzy relational equation. As they can be applied to many fields of fuzzy logic, fuzzy relational equations are of great importance; therefore, many researches have been carried out on the subject and many methods have already been proposed to solve the various kinds of fuzzy equations that can be defined, especially the so-called max-min equations. One of the main consequences of the use of the max and min operators is the non uniqueness of the solution. Indeed, when a max-min fuzzy equation has solutions, there are several solutions which can be grouped in intervals. However, most of the existing methods do not enable to calculate the widest solution sets only, often leading to calculate non-maximal solution sets, that is, solution sets included in wider sets. This often results in unnecessary calculations, requiring huge amounts of memory and time. The method we propose here enables to determine rapidly all the widest solution sets of a max-min equation, and those sets only. The use of symbol-valued matrices enables to define simple rules and makes the method very simple to apply.
A CONJECTURE TO THE SOLUTION OF THE CONTINUOUS LOGISTIC EQUATION
Authors: COHEN M. E. , HUDSON D. L. , ANDERSON M. F. , DEEDWANIA P. C.
Published: November 2004

Chaotic models as a rule are based on nonlinear recursive discrete equations, often illustrated by the logistic equation. In this paper, a conjecture is presented that gives an approximate solution to the continuous logistic equation. It is shown that if certain chaotic models are viewed as continuous rather than discrete, the strict borderline mathematical concept of the onset of chaos no longer retains its importance in some practical problems. In fact, it is more important to look at the degree of chaos, as illustrated in two medical problems dealing with blood flow and heart rate variability. The chaotic modeling approach is seen to be useful in analyzing experimental data.
HOW TO HANDLE THE FLEXIBILITY OF LINGUISTIC VARIABLES WITH APPLICATIONS
Authors: BASTIAN ANDREAS
Published: November 2004

In this paper some limitations of the conventional IF — THEN fuzzy rules due to the context dependency and rule structure are discussed. To overcome those limitations, the operational definition of a linguistic variable proposed by Zadeh is extended in such a way that a fuzzy value of a linguistic variable may take several meanings depending on the context. Applied to fuzzy controllers and models, this new operational definition leads to a new class of fuzzy controllers and models. To show its applicability this concept is applied to model the gear selection of two human drivers with different characteristics.
Molecular determinants of voltage-gated sodium channel regulation by the Nedd4/Nedd4-like proteins
Authors: Rougier Jean-Sébastien , van Bemmelen Miguel X. , Bruce M. Christine , Jespersen Thomas , Gavillet Bruno , Apothéloz Florine , Cordonier Sophie , Staub Olivier , Rotin Daniela , Abriel Hugues
Published: November 2004

The voltage-gated Na+ channels (Nav) form a family composed of 10 genes. The COOH termini of Nav contain a cluster of amino acids that are nearly identical among 7 of the 10 members. This COOH-terminal sequence, PPSYDSV, is a PY motif known to bind to WW domains of E3 protein-ubiquitin ligases of the Nedd4 family. We recently reported that cardiac Nav1.5 is regulated by Nedd4-2. In this study, we further investigated the molecular determinants of regulation of Nav proteins. When expressed in HEK-293 cells and studied using whole cell voltage clamping, the neuronal Nav1.2 and Nav1.3 were also downregulated by Nedd4-2. Pull-down experiments using fusion proteins bearing the PY motif of Nav1.2, Nav1.3, and Nav1.5 indicated that mouse brain Nedd4-2 binds to the Nav PY motif. Using intrinsic tryptophan fluorescence imaging of WW domains, we found that Nav1.5 PY motif binds preferentially to the fourth WW domain of Nedd4-2 with a Kd of ∼55 μM. We tested the binding properties and the ability to ubiquitinate and downregulate Nav1.5 of three Nedd4-like E3s: Nedd4-1, Nedd4-2, and WWP2. Despite the fact that along with Nedd4-2, Nedd4-1 and WWP2 bind to Nav1.5 PY motif, only Nedd4-2 robustly ubiquitinated and downregulated Nav1.5. Interestingly, coexpression of WWP2 competed with the effect of Nedd4-2. Finally, using brefeldin A, we found that Nedd4-2 accelerated internalization of Nav1.5 stably expressed in HEK-293 cells. This study shows that Nedd4-dependent ubiquitination of Nav channels may represent a general mechanism regulating the excitability of neurons and myocytes via modulation of channel density at the plasma membrane.
Dynamics of flow velocities in endocardial and epicardial coronary arterioles
Authors: Toyota Eiji , Ogasawara Yasuo , Hiramatsu Osamu , Tachibana Hiroyuki , Kajiya Fumihiko , Yamamori Shinji , Chilian William M.
Published: November 2004

The subendocardium is the most vulnerable area of the left ventricle to the effects of hypoperfusion and ischemia. Despite this well-acknowledged observation, the mechanisms underlying this susceptibility are not elucidated, although numerous explanations including differences in transmural distribution of hemodynamics, metabolism, and wall stresses have been proposed. Our goal was to make dynamic measurements of endocardial and epicardial flow velocities, which reflect hemodynamic and wall stresses, to approach this problem. We measured blood flow velocities in subendocardial and subepicardial coronary arterioles of in vivo beating canine hearts using a high-speed, charge-coupled device, intravital videomicroscope with a rod-probe lens. Subendocardial flow was characterized by remarkable systolic flow-velocity reversal (systolic slosh ratio, 84%; measurable velocity of retrograde flow, faster than −40 mm/s), which contrasted to predominant forward-flow velocity during systole in the subepicardial arterioles (systolic slosh ratio, 25%; maximum velocity, approximately −20 mm/s; P < 0.0005 and 0.05 vs. subendocardial arterioles, respectively). We speculate that this retrograde flow is “wasteful,” because this volume must be refilled during the subsequent diastole, which thereby detracts from the net perfusion as well as the time for perfusion. Accordingly, we also believe that the retrograde systolic blood flow contributes to the vulnerability of the subendocardium to ischemia.
Normal Performance and Expression of Learning in the Vestibulo-Ocular Reflex (VOR) at High Frequencies
Authors: Ramachandran Ramnarayan , Lisberger Stephen G.
Published: November 2004

The rotatory vestibulo-ocular reflex (VOR) keeps the visual world stable during head movements by causing eye velocity that is equal in amplitude and opposite in direction to angular head velocity. We have studied the performance of the VOR in darkness for sinusoidal angular head oscillation at frequencies ranging from 0.5 to 50 Hz. At frequencies of ≥25 Hz, the harmonic distortion of the stimulus and response were estimated to be <14 and 22%, respectively. We measured the gain of the VOR (eye velocity divided by head velocity) and the phase shift between eye and head velocity before and after adaptation with altered vision. Before adaptation, VOR gains were close to unity for frequencies ≤20 Hz and increased as a function of frequency reaching values of 3 or 4 at 50 Hz. Eye velocity was almost perfectly out of phase with head velocity for frequencies ≤12.5 Hz, and lagged perfect compensation increasingly as a function of frequency. After adaptive modification of the VOR with magnifying or miniaturizing optics, gain showed maximal changes at frequencies <12.5 Hz, smaller changes at higher frequencies, and no change at frequencies larger than 25 Hz. Between 15 and 25 Hz, the phase of eye velocity led the unmodified VOR by as much as 50° when the gain of the VOR had been decreased, and lagged when the gain of the VOR had been increased. We were able to reproduce the main features of our data with a two-pathway model of the VOR, where the two pathways had different relationships between phase shift and frequency.
Spatial Distribution of Inputs and Local Receptive Field Properties of a Wide-Field, Looming Sensitive Neuron
Authors: Krapp Holger G. , Gabbiani Fabrizio
Published: November 2004

The lobula giant movement detector (LGMD) in the locust visual system and its target neuron, the descending contralateral movement detector (DCMD), respond to approaching objects looming on a collision course with the animal. They thus provide a good model to study the cellular and network mechanisms underlying the sensitivity to this specific class of behaviorally relevant stimuli. We determined over an entire locust eye the density distribution of optical axes describing the spatial organization of local inputs to the visual system and compared it with the sensitivity distribution of the LGMD/DCMD to local motion stimuli. The density of optical axes peaks in the equatorial region of the frontal eye. Local motion sensitivity, however, peaks in the equatorial region of the caudolateral visual field and only correlates positively with the dorso-ventral density of optical axes. On local stimulation, both the velocity tuning and the response latency of the LGMD/DCMD depend on stimulus position within the visual field. Spatial and temporal integration experiments in which several local motion stimuli were activated either simultaneously or at fixed delays reveal that the LGMD processes local motion in a strongly sublinear way. Thus the neuron's integration properties seem to depend on several factors including its dendritic morphology, the local characteristics of afferent fiber inputs, and inhibition mediated by different pathways or by voltage-gated conductances. Our study shows that the selectivity of this looming sensitive neuron to approaching objects relies on more complex biophysical mechanisms than previously thought.
Whole blood and leukocyte RNA isolation for gene expression analyses
Authors: Feezor Robert J. , Baker Henry V. , Mindrinos Michael , Hayden Doug , Tannahill Cynthia L. , Brownstein Bernard H. , Fay Adrian , MacMillan Sandra , Laramie Jason , Xiao Wenzhong , Moldawer Lyle L. , Cobb J. Perren , Laudanski Krzysztof , Miller-Graziano Carol L. , Maier Ronald V. , Schoenfeld David , Davis Ronald W. , Tompkins Ronald G. ,   the Inflammation and Host Response to Injury, Large-Scale Collaborative Research Program
Published: November 2004

The analysis of gene expression data in clinical medicine has been plagued by the lack of a critical evaluation of accepted methodologies for the collection, processing, and labeling of RNA. In the present report, the reliability of two commonly used techniques to isolate RNA from whole blood or its leukocyte compartment was compared by examining their reproducibility, variance, and signal-to-noise ratios. Whole blood was obtained from healthy subjects and was either untreated or stimulated ex vivo with Staphylococcus enterotoxin B (SEB). Blood samples were also obtained from trauma patients but were not stimulated with SEB ex vivo. Total RNA was isolated from whole blood with the PAXgene proprietary blood collection system or from isolated leukocytes. Biotin-labeled cRNA was hybridized to Affymetrix GeneChips. The Pearson correlation coefficient for gene expression measurements in replicates from healthy subjects with both techniques was excellent, exceeding 0.985. Unsupervised analyses, including hierarchical cluster analysis, however, revealed that the RNA isolation method resulted in greater differences in gene expression than stimulation with SEB or among different trauma patients. The intraclass correlation, a measure of signal-to-noise ratio, of the difference between SEB-stimulated and unstimulated blood from healthy subjects was significantly higher in leukocyte-derived samples than in whole blood: 0.75 vs. 0.46 ( P = 0.002). At the P < 0.001 level of significance, twice as many probe sets discriminated between SEB-stimulated and unstimulated blood with leukocyte isolation than with PAXgene. The findings suggest that the method of RNA isolation from whole blood is a critical variable in the design of clinical studies using microarray analyses.
Polynomial algorithms for projecting a point onto a region defined by a linearconstraint and box constraints in ℝn
Authors: Stefanov Stefan M.
Published: November 2004

We consider the problem of projecting a point onto a region
defined by a linear equality or inequality constraint and
two‐sided bounds on the variables. Such problems are interesting
because they arise in various practical problems and as
subproblems of gradient‐type methods for constrained optimization.
Polynomial algorithms are proposed for solving these problems and
their convergence is proved. Some examples and results of
numerical experiments are presented.