bluuebunny/crossref_metadata_2025 huggingface dataset:
Entangled Macroscopic Quantum States in Two Superconducting Qubits
Authors: Berkley A. J. , Xu H. , Ramos R. C. , Gubrud M. A. , Strauch F. W. , Johnson P. R. , Anderson J. R. , Dragt A. J. , Lobb C. J. , Wellstood F. C.
Published: June 2003

We present spectroscopic evidence for the creation of entangled macroscopic quantum states in two current-biased Josephson-junction qubits coupled by a capacitor. The individual junction bias currents are used to control the interaction between the qubits by tuning the energy level spacings of the junctions in and out of resonance with each other. Microwave spectroscopy in the 4 to 6 gigahertzrange at 20 millikelvin reveals energy levels that agree well with theoretical results for entangled states. The single qubits are spatially separate, and the entangled states extend over the 0.7-millimeter distance between the two qubits.
Primary Electronic Thermometry Using the Shot Noise of a Tunnel Junction
Authors: Spietz Lafe , Lehnert K. W. , Siddiqi I. , Schoelkopf R. J.
Published: June 2003

We present a thermometer based on the electrical noise from a tunnel junction. In this thermometer, temperature is related to the voltage across the junction by a relative noise measurement with only the use of the electron charge, Boltzmann's constant, and assumption that electrons in a metal obey Fermi-Dirac statistics. We demonstrate proof-of-concept operation of this primary thermometer over four orders of magnitude in temperature, with as high as 0.1% accuracy and 0.02% precision in the range near 1 kelvin. The self-calibrating nature of this sensor allows for a much faster and simpler measurement than traditional Johnson noise thermometry, making it potentially attractive for metrology and for general use in cryogenic systems.
Equatorial Retention of the Contractile Actin Ring by Microtubules During Cytokinesis
Authors: Pardo Mercedes , Nurse Paul
Published: June 2003

In most eukaryotes cytokinesis is brought about by a contractile actin ring located at the division plane. Here, in fission yeast the actin ring was found to be required to generate late-mitotic microtubular structures located at the division plane, and these in turn maintained the medial position of the actin ring. When these microtubular structures were disrupted, the actin ring migrated away from the cell middle in a membrane traffic–dependent manner, resulting in asymmetrical cell divisions that led to genomic instability. We propose that these microtubular structures contribute to a checkpoint control that retains the equatorial position of the ring when progression through cytokinesis is delayed.
Programmed DNA Deletion As an RNA-Guided System of Genome Defense
Authors: Yao Meng-Chao , Fuller Patrick , Xi Xiaohui
Published: June 2003

Genomewide DNA rearrangements occur in many eukaryotes during development, but their functions and mechanisms are poorly understood. Previous studies have implicated a sequence-recognition mechanism based on RNA-mediated interactions between nuclei in ciliated protozoa. In this study, we found that the process recognized and deleted a foreign gene integrated in a
Tetrahymena
chromosome, suggesting an unusual mechanism of genome surveillance. We further found that injection of double-stranded RNA into the cell at specific developmental stages triggers efficient deletion of the targeted genomic regions. Together the results indicate an RNA-based mechanism that directs genomewide DNA rearrangements and serves to disable invading genetic agents.
Spin-Polarized Hydrogen Atoms from Molecular Photodissociation
Authors: Rakitzis T. P. , Samartzis P. C. , Toomes R. L. , Kitsopoulos T. N. , Brown Alex , Balint-Kurti G. G. , Vasyutinskii O. S. , Beswick J. A.
Published: June 2003

The production of spin-polarized hydrogen atoms from the photodissociation of hydrogen chloride with circularly polarized 193-nanometer light is inferred from the measurement of the complete angular momentum distributions of ground state Cl(
2
P
3/2
)and excited state Cl(
2
P
1/2
)cofragments by slice imaging. The experimentally measured and ab initio predicted

\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathbf{a}_{{\ }q}^{(k)}\) \end{document}

(
p
)parameters, which describe the single-surface and multiple-surface-interference contributions to the angular momentum distributions, are in excellent agreement. For laser pulses longer than about 0.7 ns, the polarization of the electron and the proton are both 36%.
Regulators of Cerebellar Granule Cell Development Act Through Specific Signaling Pathways
Authors: Vaudry David , Falluel-Morel Anthony , Leuillet Sébastien , Vaudry Hubert , Gonzalez Bruno J.
Published: June 2003

The proper development of the central nervous system depends upon a finely tuned balance between cell proliferation and programmed cell death (PCD). Although PCD was initially believed to depend solely on the inability of certain neurons to obtain access to a limited supply of trophic factors, it has become apparent that the local production of death signals is also critical. In this Viewpoint, we discuss several pathways implicated in the survival of cerebellar granule cells— both pathways that protect from apoptosis and pathways that promote apoptosis—and describe how these disparate pathways converge on the final common mediators of PCD. Information on other important pathways implicated in granule cell survival may be found in the Connections Maps.
The Dark Age of the Universe
Authors: Miralda-Escudé Jordi
Published: June 2003

The Dark Age is the period between the time when the cosmic microwave background was emitted and the time when the evolution of structure in the universe led to the gravitational collapse of objects, in which the first stars were formed. The period of reionization started with the ionizing light from the first stars, and it ended when all the atoms in the intergalactic medium had been reionized. The most distant sources of light known at present are galaxies and quasars at redshift
z
≅ 6, and their spectra indicate that the end of reionization was occurring just at that time. The Cold Dark Matter theory for structure formation predicts that the first sources formed much earlier.
Evidence for Black Holes
Authors: Begelman Mitchell C.
Published: June 2003

Black holes are common objects in the universe. Each galaxy contains large numbers—perhaps millions—of stellar-mass black holes, each the remnant of a massive star. In addition, nearly every galaxy contains a supermassive black hole at its center, with a mass ranging from millions to billions of solar masses. This review discusses the demographics of black holes, the ways in which they interact with their environment, factors that may regulate their formation and growth, and progress toward determining whether these objects really warp spacetime as predicted by the general theory of relativity.
Time to Rethink Conservation Strategy
Authors: Daily Gretchen C.
Published: June 2003

Win-Win Ecology
How the Earth's Species Can Survive in the Midst of Human Enterprise. Michael L. Rosenzweig. Oxford University Press, New York, 2003. 221 pp. $27, £19.99. ISBN 0-19-515604-8.

In this popular account full of examples, Rosenzweig develops the case for a "reconciliation" ecology of deliberately sharing our habitats with other species.
A Tree of Fireflies, a Flock of Boson Clouds
Authors: Kopell Nancy
Published: June 2003

Sync
The Emerging Science of Spontaneous Order. Steven Strogatz. Theia (Hyperion), New York, 2003. 348 pp. $24.95, C$36.95. ISBN 0-7868-6844-9. Allen Lane (Penguin), London. 352 pp. £14.99. ISBN 0-7139-9621-8.

Weaving together stories of the science and the researchers who have created it, Strogatz draws on complexity theory to discusses the emergence of order in such phenomena as orbits, firefly flashing, traffic patterns, sleep cycles, brain waves, and heart beats.
Circadian Rhythms: In the Loop at Last
Authors: Van Gelder Russell N. , Herzog Erik D. , Schwartz William J. , Taghert Paul H.
Published: June 2003

The basic molecular mechanisms underlying circadian oscillators follow the same general plan across the phylogenetic spectrum: oscillating feedback loops in which clock gene products negatively regulate their own expression. The circadian clocks of animals involve at least two interacting feedback loops. This Viewpoint compares and contrasts the circadian clocks of mammals and of
Drosophila
, emphasizing how different players are used to create the same basic script. Both the general script and the specific details of the murine and
Drosophila
circadian pathways are available at
Science
's Signal Transduction Knowledge Environment Connections Maps.
Interleukin-4 and Interleukin-13 Signaling Connections Maps
Authors: Kelly-Welch Ann E. , Hanson Erica M. , Boothby Mark R. , Keegan Achsah D.
Published: June 2003

Cytokines are inflammatory mediators important in responding to pathogens and other foreign challenges. Interleukin-4 (IL-4) and IL-13 are two cytokines produced by T helper type 2 cells, mast cells, and basophils. In addition to their physiological roles, these cytokines are also implicated in pathological conditions such as asthma and allergy. IL-4 can stimulate two receptors, type I and type II, whereas IL-13 signaling is mediated only by the type II receptor (see the STKE Connections Maps). These cytokines activate the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling cascades, which may contribute to allergic responses. In addition, stimulation of the phosphatidylinositol 3-kinase (PI3K) pathway through recruitment of members of the insulin receptor substrate family may contribute to survival and proliferation.
Toll-Like Receptor Signaling Pathways
Authors: Barton Gregory M. , Medzhitov Ruslan
Published: June 2003

Members of the Toll-like receptor (TLR) family recognize conserved microbial structures, such as bacterial lipopolysaccharide and viral double-stranded RNA, and activate signaling pathways that result in immune responses against microbial infections. All TLRs activate MyD88-dependent pathways to induce a core set of stereotyped responses, such as inflammation. However, individual TLRs can also induce immune responses that are tailored to a given microbial infection. Thus, these receptors are involved in both innate and adaptive immune responses. The mechanisms and components of these varied responses are only partly understood. Given the importance of TLRs in host defense, dissection of the pathways they activate has become an important emerging research focus. TLRs and their pathways are numerous;
Science
's Signal Transduction Knowledge Environment's TLR Connections Map provides an immediate, clear overview of the known components and relations of this complex system.
A Low-Density M-type Asteroid in the Main Belt
Authors: Margot J. L. , Brown M. E.
Published: June 2003

The orbital parameters of a satellite revolving around 22 Kalliope indicate that the bulk density of this main-belt asteroid is 2.37 ± 0.4 grams per cubic centimeter. M-type asteroids such as Kalliope are thought to be the disrupted metallic cores of differentiated bodies. The lowdensity indicates that Kalliope cannot be predominantly composed of metal and may be composed of chondritic material with ∼30% porosity. The satellite orbit is circular, suggesting that Kalliope and its satellite have different internal structures and tidal dissipation rates. The satellite may be an aggregate of impact ejecta from an earlier collision with Kalliope.
New Light on Dark Matter
Authors: Ostriker Jeremiah P. , Steinhardt Paul
Published: June 2003

Dark matter, proposed decades ago as a speculative component of the universe, is now known to be the vital ingredient in the cosmos: six times more abundant than ordinary matter, one-quarter of the total energy density, and the component that has controlled the growth of structure in the universe. Its nature remains a mystery, but assuming that it is composed of weakly interacting subatomic particles, is consistent with large-scale cosmic structure. However, recent analyses of structure on galactic and subgalactic scales have suggested discrepancies and stimulated numerous alternative proposals. We discuss how studies of the density, demography, history, and environment of smaller-scale structures may distinguish among these possibilities and shed new light on the nature of dark matter.
The New Interactionism
Authors: Laland Kevin N.
Published: June 2003

Nature via Nurture
Genes, Experience, and What Makes Us Human. Matt Ridley. HarperCollins, New York, 2003. 336 pp. $25.95. ISBN 0-06-000678-1. Fourth Estate, London. £18.99. ISBN 1-84115-745-7.

Ridley draws on findings from fields including genetics, ethology, neurobiology, psychology, and anthropology to demonstrate how the effects of genes can depend on the context in which they are expressed.
Throwing Light on Dark Energy
Authors: Kirshner Robert P.
Published: June 2003

Supernova observations show that the expansion of the universe has been speeding up. This unexpected acceleration is ascribed to a dark energy that pervades space. Supernova data, combined with other observations, indicate that the universe is about 14 billion years old and is composed of about 30%matter and 70%dark energy. New observational programs can trace the history of cosmic expansion more precisely and over a larger span of time than has been done to date to learn whether the dark energy is a modern version of Einstein's cosmological constant or another form of dark energy that changes with time. Either conclusion is an enigma that points to gaps in our fundamental understanding of gravity.
Signaling Receptome: A Genomic and Evolutionary Perspective of Plasma Membrane Receptors Involved in Signal Transduction
Authors: Ben-Shlomo Izhar , Yu Hsu Sheau , Rauch Rami , Kowalski Haili W. , Hsueh Aaron J. W.
Published: June 2003

Intercellular communication in multicellular organisms requires the relay of extracellular signals by cell surface proteins to the interiors of cells. The availability of genome sequences from humans and several model organisms has facilitated the identification of several human plasma membrane receptor families and allowed the analysis of their phylogeny. This review provides a global categorization of most known signal transduction-associated receptors as enzymes, recruiters, and latent transcription factors. The evolution of known families of human plasma membrane signaling receptors was traced in current literature and validated by sequence relatedness. This global analysis reveals themes that recur during receptor evolution and allows the formulation of hypotheses for the origins of receptors. The human receptor families involved in signaling (with the exception of channels) are presented in the
Human Plasma Membrane Receptome database
.
OPTIMAL CELLULAR NETWORK DEPLOYMENT REUSING EXISTING BASE STATIONS
Authors: FAN GUANGBIN , ZHANG JINGYUAN
Published: June 2003

Cellular communications has experienced an explosive growth recently. In order to increase the capacity of a cellular network without new frequency spectrum allocation, it is a common practice to use base stations with a lower power transmitter. Cell splitting is one of such techniques, which increases the network capacity four-fold by dividing a cell into four smaller cells. Although the cell splitting technique can reuse the existing base stations, it requires that those existing base stations be uniformly distributed. In addition, the radius of each new cell is always half that of the original cell. In this paper, it is assumed that the radius of new cells can be of any smaller size, and that the existing base stations are not necessarily uniformly distributed. While new base stations can be placed at the cell centers based on the design of the new cellular network, existing base stations should be put as close to a cell center as possible in the new cellular network. The problem to be solved, referred to as the optimal cellular network deployment, can be formulated as follows: given a set of existing base stations and a planned cellular network that has a fixed cell size and network orientation but is movable, find a position to fix the movable cellular network such that the maximum distance between existing base stations and their corresponding cell centers is minimized. This paper shows that the optimal cellular network deployment problem can be solved in O(n3) time if n existing base stations will be reused.
DISTRIBUTED SPANNERS WITH BOUNDED DEGREE FOR WIRELESS AD HOC NETWORKS
Authors: WANG YU , LI XIANG-YANG , FRIEDER OPHIR
Published: June 2003

In this paper, we review some new distributed algorithms that construct sparse subgraphs with bounded degree of the unit disk graph efficiently for wireless ad hoc networks. They maintain a linear number of links while still preserving power-efficient routes for any pair of nodes. It was open whether the Yao plus reverse Yao graph and the symmetric Yao graph are spanners. We show that the Yao plus reverse Yao graph has a bounded power stretch factor 2 in civilized unit disk graph. In addition, we review a recent example by M. Grünewald et al. [6] to show that the symmetric Yao graph does not have a constant bounded stretch factor. Finally, we conduct simulations to study the practical performances of these structures. All structures have small power stretch factors for randomly generated unit disk graphs in our experiments.
BROADCASTING IN AD HOC NETWORKS BASED ON SELF-PRUNING
Authors: WU JIE , DAI FEI
Published: June 2003

We propose a general framework for broadcasting in ad hoc networks through self-pruning. The approach is based on selecting a small subset of hosts (also called nodes) to form a forward node set on carry out a broadcast process. Each node, upon receiving a broadcast packet, determines whether to forward the packet or not based on two neighborhood coverage conditions proposed in this paper. These coverage conditions depend on neighbor connectivity and history of visited nodes, and in general, resort to global network information. Using local information such as k-hop neighborhood information, the forward node set is selected through a distributed and local pruning process. The forward node set can be constructed and maintained through either a proactive process (i.e., "up-to-date") or a reactive process (i.e., "on-the-fly"). Several existing broadcast algorithms can be viewed as special cases of the coverage conditions with k-hop neighborhood information. Simulation results show that new algorithms, which are more efficient than existing ones, can be derived from the coverage conditions, and self-pruning based on 2- or 3-hop neighborhood information is relatively more cost-effective.
FAST CLUSTERING AND MINIMUM WEIGHT MATCHING ALGORITHMS FOR VERY LARGE MOBILE BACKBONE WIRELESS NETWORKS
Authors: FERRO A. , PIGOLA G. , PULVIRENTI A. , SHASHA D.
Published: June 2003

Mobile Backbone Wireless Networks (MBWN) [10] are wireless networks in which the base stations are mobile. Our strategy is the following: mobile nodes are dynamically grouped into clusters of bounded radius. In the very large wireless networks we deal with we deal with, several hundreds of clusters may be generated. Clustering makes use of a two dimensional Euclidean version of the Antipole Tree data structure [5]. This very effective structure was originally designed for finite sets of points in an arbitrary metric space to support efficient range searching. It requires only a linear number of pair-wise distance calculations among nodes. Mobile Base Stations occupy an approximate centroid of the clusters and are moved according to a fast practical bipartite matching algorithm which tries to minimize both total and maximum distance. We show that the best known computational geometry algorithms [1] become infeasible for our application when a high number of mobile base stations is required. On the other hand our proposed 8% average error solution requires O (k log k) running time instead of the approximatively O (k2) exact algorithm [1]. Communication among nodes is realized by a Clusterhead Gateway Switching Routing (CGSR) protocol [15] where the mobile base stations are organized in a suitable network. Other efficient clustering algorithms [11, 17] may be used instead of the Antipole Tree. However the nice hierarchical structure of the Antipole Tree makes it applicable to other types of mobile wireless (Ad-Hoc) and wired networks but this will be subject of future work.
NEIGHBOR AWARE ADAPTIVE POWER FLOODING (NAAP) IN MOBILE AD HOC NETWORKS
Authors: LIPMAN JUSTIN , BOUSTEAD PAUL , JUDGE JOHN
Published: June 2003

This paper introduces Neighbor Aware Adaptive Power flooding, an optimized flooding mechanism used in mobile ad hoc networks (MANETS) that employs several mechanisms (neighbor coverage, power control, neighbor awareness and local optimization) to limit the broadcast storm problem, reduce duplicate packet reception and lower power consumption in both transmission and reception. Upon receiving an optimized broadcast, a relay determines a new set of possible relays (to continue the flood) based upon local neighbor information and the previous optimized broadcast. Additionally, neighboring relays only consider the shared neighbors they are closest to. A relay may perform local optimization (to reduce power consumption and isolate broadcasts) by substituting one high power broadcast with two or more low power broadcasts, thereby introducing additional hops, We show that compared to blind flooding and multipoint relaying, NAAP in a static environment greatly reduces the problems associated with the broadcast storm problem, duplicate packet reception and power consumption.
RNG RELAY SUBSET FLOODING PROTOCOLS IN MOBILE AD-HOC NETWORKS
Authors: CARTIGNY JULIEN , INGELREST FRANÇOIS , SIMPLOT DAVID
Published: June 2003

In this paper, we study broadcasting protocols where nodes use some of their neighbors to forward messages. We propose a new protocol based on a variant of neighbor elimination scheme using RNG graph to ensure a full coverage of the network. The computation of RNG uses two kinds of distance: a geometrical one and and neighborhood-based distance that permits to use our protocol without positioning system. This protocol, called RRS for RNG Relay Subset, provides a self-selecting forwarding neighbor operating mode which guarantees a fair broadcast loading. In RRS a node v is a relay for a node u if and only if v is a neighbor of u and v has a RNG-neighbor which is not covered by u transmission. Moreover, experiments with 802.11-like MAC layer show that RRS is efficient.
COMPUTING SHORTEST, FASTEST, AND FOREMOST JOURNEYS IN DYNAMIC NETWORKS
Authors: XUAN B. BUI , FERREIRA A. , JARRY A.
Published: June 2003

New technologies and the deployment of mobile and nomadic services are driving the emergence of complex communications networks, that have a highly dynamic behavior. This naturally engenders new route-discovery problems under changing conditions over these networks. Unfortunately, the temporal variations in the network topology are hard to be effectively captured in a classical graph model. In this paper, we use and extend a recently proposed graph theoretic model, which helps capture the evolving characteristic of such networks, in order to propose and formally analyze least cost journey (the analog of paths in usual graphs) in a class of dynamic networks, where the changes in the topology can be predicted in advance. Cost measures investigated here are hop count (shortest journeys), arrival date (foremost journeys), and time span (fastest journeys).
MAXIMAL INDEPENDENT SET, WEAKLY-CONNECTED DOMINATING SET, AND INDUCED SPANNERS IN WIRELESS AD HOC NETWORKS
Authors: ALZOUBI KHALED M. , WAN PENG-JUN , FRIEDER OPHIR
Published: June 2003

A maximal independent set (MIS) S for a graph G is an independent set and no proper superset of S is also independent. A set S is dominating if each node in the graph is either in S or adjacent to one of the nodes in S. The subgraph weakly induced by S is the graph G′ such that each edge in G′ has at least one end point in S. A set S is a weakly-connected dominating set (WCDS) of G if S is dominating and G′ is connected. G′ is a sparse spanner if it has linear edges. The nodes of WCDS have been proposed in the literature as clusterheads for clustered wireless ad hoc networks. In this paper, we present two distributed algorithms for constructing a WCDS for wireless ad hoc networks in linear time. The first algorithm has an approximation ratio of 5, and requires O(n log n) messages, while the second algorithm has a larger approximation ratio, and requires only O(n) messages. Both of these algorithms are used to obtain sparse spanners. The spanner obtained by the second algorithm has a topological dilation of 3, and a geometric dilation of 6. Both of these algorithms are based on the construction of a MIS. The first algorithm requires the construction of a spanning tree. The second algorithm is fully localized, and does not depend on the spanning tree, which makes the maintenance of the WCDS simpler, and guarantees the maintenance of the same approximation ratio.
A ZONAL ALGORITHM FOR CLUSTERING AN HOC NETWORKS
Authors: CHEN YUANZHU PETER , LIESTMAN ARTHUR L.
Published: June 2003

A Mobile Ad Hoc Network (MANET) is an infrastructureless wireless network that can support highly dynamic mobile units. The multi-hop feature of a MANET suggests the use of clustering to simplify routing. Graph domination can be used in defining clusters in MANETs. A variant of dominating set which is more suitable for clustering MANETs is the weakly-connected dominating set. A cluster is defined to be the set of vertices dominated by a particular vertex in the dominating set. As it is NP-complete to determine whether a given graph has a weakly-connected dominating set of a particular size, we present a zonal distributed algorithm for finding small weakly-connected dominating sets. In this new approach, we divide the graph into regions, construct a weakly-connected dominating set for each region, and make adjustments along the borders of the regions to produce a weakly-connected dominating set of the entire graph. We present experimental evidence that this zonal algorithm has similar performance to and provides better cluster connectivity than previous algorithms.
A SIMPLE HEURISTIC FOR MINIMUM CONNECTED DOMINATING SET IN GRAPHS
Authors: WAN PENG-JUN , ALZOUBI KHALED M. , FRIEDER OPHIR
Published: June 2003

Let α2(G), γ(G) and γc(G) be the 2-independence number, the domination number, and the connected domination number of a graph G respectively. Then α2(G) ≤ γ (G) ≤ γc(G). In this paper , we present a simple heuristic for Minimum Connected Dominating Set in graphs. When running on a graph G excluding Km (the complete graph of order m) as a minor, the heuristic produces a connected dominating set of cardinality at most 7α2(G) - 4 if m = 3, or at most [Formula: see text] if m ≥ 4. In particular, if running on a planar graph G, the heuristic outputs a connected dominating set of cardinality at most 15α2(G) - 5.
AGING IN A ONE-DIMENSIONAL EDWARDS–ANDERSON SPIN GLASS MODEL WITH LONG-RANGE INTERACTIONS
Authors: MONTEMURRO MARCELO A. , TAMARIT FRANCISCO A.
Published: June 2003

In this work we study, by means of numerical simulations, the out-of-equilibrium dynamics of the one-dimensional Edwards–Anderson model with long-range interactions of the form ± Jr-α. In the limit α → 0 we recover the well known Sherrington–Kirkpatrick mean-field version of the model, which presents a very complex dynamical behavior. At the other extreme, for α → ∞ the model converges to the nearest-neighbor one-dimensional system. We focus our study on the dependence of the dynamics on the history of the sample (aging phenomena) for different values of α. The model is known to have mean-field exponents already for values of α = 2/3. Our results indicate that the crossover to the dynamic mean-field occurs at a value of α < 2/3.
MODULO THREE PROBLEM WITH A CELLULAR AUTOMATON SOLUTION
Authors: XU HAO , LEE K. M. , CHAU H. F.
Published: June 2003

An important global property of a bit string is the number of ones in it. It has been found that the parity (odd or even) of this number can be found by a sequence of deterministic, translational invariant cellular automata with parallel update in succession for a total of O(N2) time. In this paper, we discover a way to check if this number is divisible by three using the same kind of cellular automata in O(N3) time. We also speculate that the method described here could be generalized to check if it is divisible by four and other positive integers.
THEORY OF SELF-SIMILAR OSCILLATORY FINITE-TIME SINGULARITIES
Authors: SORNETTE D. , IDE K.
Published: June 2003

A simple two-dimensional system is introduced which suggests a qualitative dynamical relationship between (1) stock market prices in the presence of nonlinear trend-followers and nonlinear value investors, (2) the world human population with a competition between a population-dependent growth rate and a nonlinear dependence on a finite carrying capacity and (3) the failure of materials subjected to a time-varying stress with a competition between positive geometrical feedback on the damage variable and nonlinear healing. Our model keeps three key ingredients (inertia, nonlinear positive and negative feedbacks) that compete to give rise to singularities in finite time decorated by accelerating oscillations.
NEW JACOBI ELLIPTIC FUNCTION SOLUTIONS OF (2 +1)-DIMENSIONAL COMPLEX NONLINEAR INTEGRABLE SYSTEM
Authors: YAN ZHENYA
Published: June 2003

Recently sixteen types of doubly-periodic solutions were obtained for the new (2 +1)-dimensional complex nonlinear integrable system. In this paper with the aid of computerized symbolic computation, our extended Jacobi elliptic function expansion method is extended to this system. As a result, another eight families of Jacobian elliptic functions solutions are also found.
OPTIMAL TRANSITION RATE AND STOCHASTIC RESONANCE IN A BISTABLE SYSTEM DRIVEN BY POWER-LAW NOISE
Authors: FREITAS J. F. L. , LYRA M. L.
Published: June 2003

In this work, we study the stochastic resonance phenomenon in a bistable nonlinear dynamical system in the presence of an uncorrelated noise source whose distribution decays asymptotically as P(ξ) ∝ 1/ξ2α. We investigate the influence of the decay exponent α on the transition rate and on the optimal noise intensity giving the maximum signal-to-noise ratio when a weak periodic signal is superposed to the external noise. We find that the transition rate achieves a maximum for a finite decay exponent α. However, the optimal noise intensity for stochastic resonance depicts a monotonic power-law correction relative to the usual behavior of nonlinear dynamical systems driven by Gaussian noises.
FINDING LOW-TEMPERATURE STATES WITH PARALLEL TEMPERING, SIMULATED ANNEALING AND SIMPLE MONTE CARLO
Authors: MORENO J. J. , KATZGRABER HELMUT G. , HARTMANN ALEXANDER K.
Published: June 2003

Monte Carlo simulation techniques, like simulated annealing and parallel tempering, are often used to evaluate low-temperature properties and find ground states of disordered systems. Here we compare these methods using direct calculations of ground states for three-dimensional Ising diluted antiferromagnets in a field (DAFF) and three-dimensional Ising spin glasses (ISG). For the DAFF, we find that, with respect to obtaining ground states, parallel tempering is superior to simple Monte Carlo and to simulated annealing. However, equilibration becomes more difficult with increasing magnitude of the externally applied field. For the ISG with bimodal couplings, which exhibits a high degeneracy, we conclude that finding true ground states is easy for small systems, as is already known. But finding each of the degenerate ground states with the same probability (or frequency), as required by Boltzmann statistics, is considerably harder and becomes almost impossible for larger systems.
IMMIGRATION, INTEGRATION AND GHETTO FORMATION
Authors: MEYER-ORTMANNS HILDEGARD
Published: June 2003

We study ghetto formation in a population with natives and immigrants in the framework of the two-dimensional Ising-model with Kawasaki-exchange dynamics. It is the phase structure of the Ising model, the integration speed and the immigration rate which determine whether ghetto formation between natives and immigrants can be avoided or not. Our simulations are performed in- and out-of-equilibrium.
A SCILAB PROGRAM FOR COMPUTING GENERAL-RELATIVISTIC MODELS OF ROTATING NEUTRON STARS BY IMPLEMENTING HARTLE'S PERTURBATION METHOD
Authors: PAPASOTIRIOU P. J. , GEROYANNIS V. S.
Published: June 2003

We implement Hartle's perturbation method to the computation of relativistic rigidly rotating neutron star models. The program has been written in SCILAB (© INRIA–ENPC), a matrix-oriented high-level programming language. The numerical method is described in very detail and is applied to many models in slow or fast rotation. We show that, although the method is perturbative, it gives accurate results for all practical purposes and it should prove an efficient tool for computing rapidly rotating pulsars.
GENERALIZED (m, k)-ZipfLAW FOR FRACTIONAL BROWNIAN MOTION-LIKE TIME SERIES WITH OR WITHOUT EFFECT OF AN ADDITIONAL LINEAR TREND
Authors: BRONLET PH. , AUSLOOS M.
Published: June 2003

We have translated fractional Brownian motion (FBM) signals into a text based on two "letters", as if the signal fluctuations correspond to a constant stepsize random walk. We have applied the Zipf method to extract the ζ′ exponent relating the word frequency and its rank on a log–log plot. We have studied the variation of the Zipf exponent(s) giving the relationship between the frequency of occurrence of words of length m < 8 made of such two letters: ζ′ is varying as a power law in terms of m. We have also searched how the ζ′ exponent of the Zipf law is influenced by a linear trend and the resulting effect of its slope. We can distinguish finite size effects, and results depending whether the starting FBM is persistent or not, i.e., depending on the FBM Hurst exponent H. It seems then numerically proven that the Zipf exponent of a persistent signal is more influenced by the trend than that of an antipersistent signal. It appears that the conjectured law ζ′ = |2H - 1| only holds near H = 0.5. We have also introduced considerations based on the notion of a time dependent Zipf law along the signal.
MUON CATALYZED FUSION DYNAMICS IN SOLID HETEROGENEOUS H/D/T MIXTURE AND ITS COMPARISON WITH SOLID HOMOGENEOUS D/T SYSTEM
Authors: ESKANDARI M. R. , SHIRAZI K. R.
Published: June 2003

The Ramsauer–Townsend effect in hydrogen is used to force the muonic tritium in suggested heterogeneous solid hydrogen–deuterium–tritium (H/D/T) multilayer system to provide resonance muonic deuterium–tritium molecule formation. The written coupled linear point dynamical equations for the suggested system are solved by Monte-Carlo method using "Lsode" computer code. The obtained results for the optimum layer thicknesses and tritium concentration are compared with the results of solid homogeneous deuterium–tritium system in the same physical condition (temperature, density and tritium concentration). It is shown that for the same physical conditions, the muon cycling coefficient of two isotopes of deuterium–tritium (D/T) has only 3% muon cycling coefficient of suggested heterogeneous solid forced H/D/T fusion system. It is shown that with very little tritium concentration (ct = 0.005) the obtained muon cycling rate and coefficient are ~ 120 μs-1 and 165 respectively.
SPECTRAL PROPERTIES OF REVERSIBLE ONE-DIMENSIONAL CELLULAR AUTOMATA
Authors: MORA JUAN CARLOS SECK TUOH , VERGARA SERGIO V. CHAPA , MARTÍNEZ GENARO JUÁREZ , McINTOSH HAROLD V.
Published: June 2003

Reversible cellular automata are invertible dynamical systems characterized by discreteness, determinism and local interaction. This article studies the local behavior of reversible one-dimensional cellular automata by means of the spectral properties of their connectivity matrices. We use the transformation of every one-dimensional cellular automaton to another of neighborhood size 2 to generalize the results exposed in this paper. In particular we prove that the connectivity matrices have a single positive eigenvalue equal to 1; based on this result we also prove the idempotent behavior of these matrices. The significance of this property lies in the implementation of a matrix technique for detecting whether a one-dimensional cellular automaton is reversible or not. In particular, we present a procedure using the eigenvectors of these matrices to find the inverse rule of a given reversible one-dimensional cellular automaton. Finally illustrative examples are provided.
DOCUMENT GRAY-SCALE REDUCTION USING A NEURO-FUZZY TECHNIQUE
Authors: PAPAMARKOS NIKOS
Published: June 2003

This paper proposes a new neuro-fuzzy technique suitable for binarization and gray-scale reduction of digital documents. The proposed approach uses both the image gray-scales and additional local spatial features. Both, gray-scales and local feature values feed a Kohonen Self-Organized Feature Map (SOFM) neural network classifier. After training, the neurons of the output competition layer of the SOFM define two bilevel classes. Using the content of these classes, fuzzy membership functions are obtained that are next used by the fuzzy C-means (FCM) algorithm in order to reduce the character-blurring problem. The method is suitable for improving blurring and badly illuminated documents and can be easily modified to accommodate any type of spatial characteristics.
FORMAL ASPECTS OF A MULTIPLE-RULE CLASSIFIER
Authors: TKADLEC JOSEF , BRUHA IVAN
Published: June 2003

This paper deals with the multiple-rule problem which arises when several decision rules (of different classes) match ("fire" for) an input to-be-classified (unseen) object. The paper focuses on formal aspects and theoretical methodology for the above problem.

The general definitions of the notions of a Designer, Learner and Classifier are presented in a formal matter, including parameters that are usually attached to the above concepts such as rule consistency, completeness, quality, matching rate, etc. We thus provide the minimum-requirement definitions as necessary conditions for these concepts. Any designer (decision-system builder) of a new multiple-rule system may start with these minimum requirements.

We only expect that the Classifier makes its decisions according to its decision scheme induced as a knowledge base (theory, model, concept description). Also, two case studies are discussed. We conclude with a general flow chart for a decision-system builder. He/she can just pursue it and select parameters of a Learner and Classifier, following the minimum requirements provided.
External Rotation Osteotomy of Femur in Patients with Spastic Cerebral Palsy
Authors: Kuo Ken N. , Hang David W. , Smith Peter A.
Published: June 2003

Fifteen subjects with ambulatory spastic cerebral palsy underwent proximal femoral external rotation osteotomy between 1990 to 1992 for severe intoeing gait due to internal femoral torsion. Among them 13 patients returned for follow-up.

Preoperatively, maximum internal rotation of the hip on physical examination corrected from 77° to 50° postoperatively. Foot progression angle changed from 10° intoeing gait preoperatively to 9° outtoeing gait postoperatively ( p < 0.05). The recurrence rate for internal femoral torsion after correction is 9.5 degrees/year for the group of 10-year-olds and younger, and 2.1 degrees/year for the group older than 10-year-olds. In the kinematic study, foot progression angle changed from internal rotation of 9.2° to external rotation of 16.5° ( p < 0.05).

Our study showed that external rotation osteotomy of the femur is a safe and effective procedure. The rate of recurrence for femoral internal torsion was greater for younger patients (≤10-year-old) when the surgery was performed.
Interbody Cages in Plif Surgery: A Multicentric Report
Authors: Depraetere P. , Jenny Ph.
Published: June 2003

Interbody cages and PLIF technique for the reconstruction of the anterior column has evolved from a controversial to an accepted and effective procedure. 285 patients operated on with Ogival Cages have been reviewed considering the indications, complications rate and the overall satisfying patient outcome. Despite the fact that this surgical technique is both time consuming and involves great care on the part of the surgeon, spondylolisthesis and degenerative disc derangements are good indications for cages and a high rate of good clinical results has been achieved with this method. Learning curve and design improvement may minimize the risk of complication.
Video-Assisted Thoracoscopic Spinal Surgery: Technical Considerations and Preliminary Clinical Outcomes
Authors: Huang Tsung-Jen , Hsu Robert Wen-Wei , Liu Hui-Ping , Liao Yi-Shyan , Chen Yeung-Jen , Hsu Kuo-Yao , Shih Hsin-Nung
Published: June 2003

Video-assisted thoracoscopic surgery (VATS) has only recently been applied in a variety of spinal procedures. Between November 1, 1995 and May 31, 1996, we used a new approach, the so-called "extended manipulating channel method", to treat 23 patients with anterior spinal abnormalities. The size of the thoracoscopic portals was made larger than usual, and placed more posteriorly so as to allow thoracoscopy and conventional spinal instruments to enter the chest cavity freely and to be manipulated similarly to techniques used in standard open surgical procedures. The total blood loss ranged from 100 to 3000 ml (average 1050 ml) and the total duration of surgery was 1 to 7.2 hours (average 3.7 hours). There was no injury to the internal organs, great vessels or the spinal cord intraoperatively. On the basis of these results, we believe that a combination of the use of thoracoscopy and conventional spinal instruments, as presented in this report, can be an ideal method for performing VATS spinal procedures. This type of approach makes endoscopic spinal surgery simpler to perform. Most complications in our patients were minor. This procedure is contraindicated for patients with severe pleurodesis or intolerance to intraoperative one-lung ventilation.
The Functional Assessment of the Untreated and the Reconstructed Posterior Cruciate Ligament Deficient Knee
Authors: Hsu Robert Wen-Wei , Cheng Cheng-Kung , Lin Yang-Hua
Published: June 2003

Seventeen patients with rupture of the posterior cruciate ligament (PCL), 7 untreated and 10 having reconstruction of the PCL using the medial head of the gastrocnemius and the attached adductor tendon, were recruited for functional evaluation.

The clinical functional status of the knee joint was evaluated in accordance with Hughston's criteria and Lysholm's score. The patients' gaits were analyzed using a three-dimensional electrogoniometer and mats. Muscle strength was assessed via Cybex-340; and a KT-1000 arthrometer was used to measure the laxity of the knee joints.

Muscle strength tests showed a significant difference ( p < 0.01) in the knee extensors when the injured side was compared with the noninjured side in the untreated group, while no significant difference existed in reconstructed group. The gait analysis revealed that a significant difference existed over the velocity ( p < 0.05) when the reconstructed group was compared with the untreated group. The KT-1000 arthrometer test demonstrated that the anterior and posterior drawer at a knee flexion of 70 degrees and the posterior tibial sag screen at 90 degrees, differed significantly ( p < 0.01) between injured and noninjured limbs in the untreated group. In the reconstructed group only the anterior drawer presented a significant difference ( p < 0.05) between the injured and noninjured limbs. Using Hughston's and Lysholm's criteria, reconstruction was shown to have improved the knees' functions and scores postoperatively ( p < 0.01).

The authors concluded that although the overall clinical results along with dynamic function, stability and strength of the extensor of the knee joints with PCL deficiency, were significantly improved after reconstruction using the medial head of the gastrocnemius together with the adductor tendon, yet, the normal perfect knee functions were still not achieved. A more sophisticated reconstructive procedure needs further investigation.
The Effect of Cyclosporine a On Xenogeneic Moose (Alces Alces) Bone Morphogenetic Protein-Induced Immune Inhibition of Heterotopic Osteoinduction in the Rat Guided Muscle Island Flap Bioassay Model
Authors: Vilijanen Veikko V. , Gao Tie-Jun , Laitinen Minna , Sam Lindholm T.
Published: June 2003

Experimental heterotopic osteoinduction can be induced to take place in a pre-determined intramuscular space using a standard-sized membrane cylinder around a vascular muscle island flap, and implanting an osteoinductive agent such as bone morphogenetic protein (BMP) and demineralized bone matrix (DBM) inside the flap. This kind of newly introduced guided muscle assay method, analyzed by radiomorphometry and histology, was used to study quantitative differences in the osteoinductive activities of xenogenic moose BMP (mBMP) and allogeneic DBM in the Wistar rat, as well as the effect of cyclosporine A (CyA).

Calcified tissue in the flaps was quantified by computerized radiomorphometry at 21 days from implantation in five experimental groups: 1) partially purified mBMP; 2)mBMP with CyA treatment; 3) mBMP Plus active allogeneic DBM with CyA; 4) active allogeneic DBM alone; and 5) inactive DBM (control). The results were presented as radiopacity percentages of normal rat femoral bone values (=100). New bone formation was confirmed by microscopy of hematoxylin-eosin and azure II-stained samples.

The mean radiopacity, compared to mean rat femoral bone values (=100%), in the mBMP group was 20%. This did not significantly exceed the result in the control flaps with inactive DBM. When CyA was administered perorally to mBMP-implanted animals, the radiopacity increased from 20% to 35% ( p =0.026). When active allogeneic DBM was added to this combination, the increase was up to 53% ( p =0.002). Implantation of active allogeneic DBM alone gave 60%. In microscopy, cartilage was the main sign of tissue transformation in the mBMP-implanted groups without DBM, and new bone with marrow in the active allogeneic DBM-implanted groups. In the control flaps with inactive DBM, no bone or cartilage developed.

The quantity of new bone formation with mBMP could be significantly improved with CyA, but not to the superior level induced by active allogeneic DBM. The findings were explained by the marked immunogenicity of xenogeneic partially purified BMP.

The advantage of the new model, compared to the conventional intramuscular assays, is a reduction of variability in soft tissue intensities of the measured objects. The standard volume reserved for osteoinduction to take place will make the model also eminently suitable for histomorphometry.
Kinematics and Laxity of Ulnohumeral Joint Under Valgus-Varus Stress
Authors: Tanaka Shinji , An Kai-Nan , Morrey Bernard F.
Published: June 2003

Three-dimensional kinematics of the ulnohumeral joint under simulated active elbow joint flexion-extension was obtained by using an electromagnetic tacking device. The joint motion was analyzed based on Eulerian angle description. In order to minimize the effect of "downstream cross-talk" on calculation of the three Eulerian angles, an optimal axis to best represent flexion-extension of the elbow joint was established. This axis, on average, is close to the line joining the centers of the capitellum and the trochlear groove. Furthermore, joint laxity under valgus-varus stress was also examined. With the weight of the forearm as the stress, maximums of 7.6° valgus-varus laxity and 5.3° axial rotation laxity were observed within a range of elbow flexion. The results of this study provide useful baseline information on joint laxity for the evaluation of elbow joints with implant replacements and other surgical treatment modalities.