bluuebunny/crossref_metadata_2025 huggingface dataset:
Microdialysis Study of Imipenem Distribution in the Peritoneal Fluid of Rats with Experimental Acute Pancreatitis
Authors: Lefeuvre Sandrine , Marchand Sandrine , Pariat Claudine , Lamarche Isabelle , Couet William
Published: January 2008

Imipenem distribution was characterized by microdialysis in the peritoneal fluid of rats with experimental pancreatitis. The ratios of peritoneal fluid to blood area under unbound concentration-versus-time curves were close to unity, suggesting that imipenem was not degraded in peritoneal fluid.
Both Decorin-Binding Proteins A and B Are Critical for the Overall Virulence of
Borrelia burgdorferi
Authors: Shi Yanlin , Xu Qilong , McShan Kristy , Liang Fang Ting
Published: January 2008

Both decorin-binding proteins (DbpA and DbpB) of the Lyme disease spirochete
Borrelia burgdorferi
bind decorin and glycosaminoglycans, two important building blocks of proteoglycans that are abundantly found in the extracellular matrix (ECM) and connective tissues as well as on cell surfaces of mammals. As an extracellular pathogen,
B. burgdorferi
resides primarily in the ECM and connective tissues and between host cells during mammalian infection. The interactions of
B. burgdorferi
with these host ligands mediated by DbpA and DbpB potentially influence various aspects of infection. Here, we show that both DbpA and DbpB are critical for the overall virulence of
B. burgdorferi
in the murine host. Disruption of the
dbpBA
locus led to nearly a 10
4
-fold increase in the 50% infectious dose (ID
50
). Complementation of the mutant with either
dbpA
or
dbpB
reduced the ID
50
from over 10
4
to roughly 10
3
organisms. Deletion of the
dbpBA
locus affected colonization in all tissues of infected mice. The lack of
dbpA
alone precluded the pathogen from colonizing the heart tissue, and
B. burgdorferi
deficient for DbpB was recovered only from 42% of the heart specimens of infected mice. Although
B. burgdorferi
lacking either
dbpA
or
dbpB
was consistently grown from joint specimens of almost all infected mice, it generated bacterial loads significantly lower than the control. The deficiency in either DbpA or DbpB did not reduce the bacterial load in skin, but lack of both significantly did. Taken together, the study results indicate that neither DbpA nor DbpB is essential for mammalian infection but that both are critical for the overall virulence of
B. burgdorferi
.
Detection of
Bacillus anthracis
Spore Germination In Vivo by Bioluminescence Imaging
Authors: Sanz Patrick , Teel Louise D. , Alem Farhang , Carvalho Humberto M. , Darnell Stephen C. , O'Brien Alison D.
Published: January 2008

We sought to visualize the site of
Bacillus anthracis
spore germination in vivo. For that purpose, we constructed a reporter plasmid with the
lux
operon under control of the spore small acid-soluble protein B (
sspB
) promoter. In
B. subtilis
,
sspB
-driven synthesis of luciferase during sporulation results in incorporation of the enzyme in spores. We observed that
B. anthracis
Sterne transformed with our
sspBp
::
lux
plasmid was only luminescent during germination. In contrast, Sterne transformed with a similarly constructed plasmid with
lux
expression under control of the protective antigen promoter displayed luminescence only during vegetative growth. We then infected A/J mice intranasally with spores that harbored the germination reporter. Mice were monitored for up to 14 days with the Xenogen In Vivo Imaging System. While luminescence only became evident in live animals at 18 h, dissection after sacrificing infected mice at earlier time points revealed luminescence in lung tissue at 30 min after intranasal infection. Microscopic histochemical and immunofluorescence studies on luminescent lung sections and imprints revealed that macrophages were the first cells in contact with the
B. anthracis
spores. By 6 h after infection, polymorphonuclear leukocytes with intracellular spores were evident in the alveolar spaces. After 24 h, few free spores were observed in the alveolar spaces; most of the spores detected by immunofluorescence were in the cytoplasm of interstitial macrophages. In contrast, mediastinal lymph nodes remained nonluminescent throughout the infection. We conclude that in this animal system, the primary site of
B. anthracis
spore germination is the lungs.
Burkholderia cenocepacia
Requires the RpoN Sigma Factor for Biofilm Formation and Intracellular Trafficking within Macrophages
Authors: Saldías M. Soledad , Lamothe Julie , Wu Robert , Valvano Miguel A.
Published: January 2008

Chronic respiratory infections by
Burkholderia cenocepacia
in cystic fibrosis patients are associated with increased morbidity and mortality, but virulence factors determining the persistence of the infection in the airways are not well characterized. Using a chronic pulmonary infection model, we previously identified an attenuated mutant with an insertion in a gene encoding an RpoN activator protein, suggesting that RpoN and/or components of the RpoN regulon play a role in
B. cenocepacia
virulence. In this study, we demonstrate that a functional
rpoN
gene is required for bacterial motility and biofilm formation in
B. cenocepacia
K56-2. Unlike other bacteria, RpoN does not control flagellar biosynthesis, as evidenced by the presence of flagella in the
rpoN
mutant. We also demonstrate that, in macrophages, the
rpoN
mutant is rapidly trafficked to lysosomes while intracellular wild-type
B. cenocepacia
localizes in bacterium-containing vacuoles that exhibit a pronounced delay in phagolysosomal fusion. Rapid trafficking to the lysosomes is also associated with the release of red fluorescent protein into the vacuolar lumen, indicating loss of bacterial cell envelope integrity. Although a role for RpoN in motility and biofilm formation has been previously established, this study is the first demonstration that the RpoN regulon in
B. cenocepacia
is involved in delaying phagolysosomal fusion, thereby prolonging bacterial intracellular survival within macrophages.
In Vivo Fate and Distribution of Poly-γ-
d
-Glutamic Acid, the Capsular Antigen from
Bacillus anthracis
Authors: Sutherland Marjorie D. , Thorkildson Peter , Parks Samuel D. , Kozel Thomas R.
Published: January 2008

Bacillus anthracis
is surrounded by an antiphagocytic capsule composed of poly-γ-
d
-glutamic acid (γDPGA). Bacterial and fungal capsular polysaccharides are shed into body fluids in large amounts during infection. The goal of our study was to examine the in vivo fate and distribution of the γDPGA capsular polypeptide. Mice were injected via the intravenous route with various amounts of purified γDPGA. Blood, urine, and various organs were harvested at different times after treatment. Sites of γDPGA accumulation were determined by immunoassay using monoclonal antibodies specific for γDPGA. The results showed that the liver and spleen were the primary sites for the accumulation of γDPGA. As found in previous studies of capsular polysaccharides, the Kupffer cells of the liver and splenic macrophages were sites for the cellular accumulation of γDPGA. Unlike capsular polysaccharides, the hepatic sinusoidal endothelial cells were also sites for γDPGA accumulation. γDPGA was rapidly cleared from serum and was excreted into the urine. γDPGA in the urine showed a reduced molecular size relative to native γDPGA. The results indicate that in vivo clearance of the polypeptide capsular antigen of
B. anthracis
shares several features with the clearance of capsular polysaccharides. Key differences between the in vivo behaviors of γDPGA and capsular polysaccharides include the accumulation of γDPGA in hepatic sinusoidal endothelial cells and a γDPGA clearance rate that was more rapid than the clearance reported for capsular polysaccharides.
Role and Regulation of Iron-Sulfur Cluster Biosynthesis Genes in
Shigella flexneri
Virulence
Authors: Runyen-Janecky Laura , Daugherty Aaron , Lloyd Benjamin , Wellington Christopher , Eskandarian Haig , Sagransky Matthew
Published: January 2008

Shigella flexneri
, a causative agent of bacterial dysentery, possesses two predicted iron-sulfur cluster biosynthesis systems called Suf and Isc.
S. flexneri
strains containing deletion mutations in the entire
suf
operon (UR011) or the
iscSUA
genes (UR022) were constructed. Both mutants were defective in surviving exposure to oxidative stress. The
suf
mutant showed growth that was comparable to that of the parental strain in both iron-replete and iron-limiting media; however, the
isc
mutant showed reduced growth, relative to the parental strain, in both media. Although the
suf
mutant formed wild-type plaques on Henle cell monolayers, the
isc
mutant was unable to form plaques on Henle cell monolayers because the strain was noninvasive. Expression from both the
suf
and
isc
promoters increased in iron-limiting media and in the presence of hydrogen peroxide. Iron repression of the
suf
promoter was mediated by Fur, and increased
suf
expression in iron-limiting media was enhanced by the presence of IscR. Iron repression of the
isc
promoter was mediated by IscR. Hydrogen peroxide-dependent induction of
suf
expression, but not
isc
expression, was mediated by OxyR. Furthermore, IscR was a positive regulator of
suf
expression in the presence of hydrogen peroxide and a negative regulator of
isc
expression in the absence of hydrogen peroxide. Expression from the
S. flexneri suf
and
isc
promoters increased when
Shigella
was within Henle cells, and our data suggest that the intracellular signal mediating this increased expression is reduced iron levels.
Development of
Galleria mellonella
as an Alternative Infection Model for the
Burkholderia cepacia
Complex
Authors: Seed Kimberley D. , Dennis Jonathan J.
Published: January 2008

Burkholderia
is an important bacterial genus with a complex taxonomy that contains species of both ecological and pathogenic importance, including nine closely related species collectively termed the
Burkholderia cepacia
complex (BCC). In order to more thoroughly investigate the virulence of this bacterial complex of microorganisms, alternative infection models would be useful. To this end, we have adapted and developed the use of the
Galleria mellonella
wax moth larvae as a host for examining BCC infections. The experimental conditions affecting the BCC killing of the “wax worm” were optimized. BCC virulence levels were determined using 50% lethal doses, and differences were observed between both species and strains of the BCC. The BCC pathogenicity trends obtained compare favorably with results acquired using other published alternative infection models, as well as mammalian infection models. In addition, BCC killing activity was determined by directly measuring relative bacterial loads in three different BCC strains, thus demonstrating innate differences in BCC strain virulence. Finally, genetically mutated BCC strains were compared to a wild-type BCC strain in order to show concomitant reduction of BCC virulence and increased wax worm survival. For experimentation examining the virulent properties of the BCC, the wax worm has proven to be a useful alternative infection model.
Critical Involvement of Pneumolysin in Production of Interleukin-1α and Caspase-1-Dependent Cytokines in Infection withStreptococcus pneumoniaeIn Vitro: a Novel Function of Pneumolysin in Caspase-1 Activation
Authors: Shoma Shereen , Tsuchiya Kohsuke , Kawamura Ikuo , Nomura Takamasa , Hara Hideki , Uchiyama Ryosuke , Daim Sylvia , Mitsuyama Masao
Published: January 2008

Pneumolysin is a pore-forming cytolysin known as a major virulence determinant ofStreptococcus pneumoniae. This protein toxin has also been shown to activate the Toll-like receptor 4 (TLR4) signaling pathway. In this study, a mutantS. pneumoniaestrain deficient in pneumolysin (Δply) and a recombinant pneumolysin protein (rPLY) were constructed. Upon infection of macrophages in vitro, the ability to induce the production of interleukin-1α (IL-1α), IL-1β, and IL-18 was severely impaired in the Δplymutant, whereas there was no marked difference in the induction of tumor necrosis factor alpha (TNF-α) and IL-12p40 between the wild type and the Δplymutant ofS. pneumoniae. When macrophages were stimulated with rPLY, the production of IL-1α, IL-1β, and IL-18 was strongly induced in a TLR4-dependent manner, whereas lipopolysaccharide, a canonical TLR4 agonist, hardly induced these cytokines. In contrast, lipopolysaccharide was more potent than rPLY in inducing the production of TNF-α, IL-6, and IL-12p40, the cytokines requiring no caspase activation. Activation of caspase-1 was observed in macrophages stimulated with rPLY but not in those stimulated with lipopolysaccharide, and the level of activation was higher in macrophages infected with wild-typeS. pneumoniaethan in those infected with the Δplymutant. These results clearly indicate that pneumolysin plays a key role in the host response toS. pneumoniae, particularly in the induction of caspase-1-dependent cytokines.
Host Airway Proteins Interact withStaphylococcus aureusduring Early Pneumonia
Authors: Ventura Christy L. , Higdon Roger , Kolker Eugene , Skerrett Shawn J. , Rubens Craig E.
Published: January 2008

Staphylococcus aureusis a major cause of hospital-acquired pneumonia and is emerging as an important etiological agent of community-acquired pneumonia. Little is known about the specific host-pathogen interactions that occur whenS. aureusfirst enters the airway. A shotgun proteomics approach was utilized to identify the airway proteins associated withS. aureusduring the first 6 h of infection. Host proteins eluted from bacteria recovered from the airways of mice 30 min or 6 h following intranasal inoculation under anesthesia were subjected to liquid chromatography and tandem mass spectrometry. A total of 513 host proteins were associated withS. aureus30 min and/or 6 h postinoculation. A majority of the identified proteins were host cytosolic proteins, suggesting thatS. aureuswas rapidly internalized by phagocytes in the airway and that significant host cell lysis occurred during early infection. In addition, extracellular matrix and secreted proteins, including fibronectin, antimicrobial peptides, and complement components, were associated withS. aureusat both time points. The interaction of 12 host proteins shown to bind toS. aureusin vitro was demonstrated in vivo for the first time. The association of hemoglobin, which is thought to be the primary staphylococcal iron source during infection, withS. aureusin the airway was validated by immunoblotting. Thus, we used our recently developedS. aureuspneumonia model and shotgun proteomics to validate previous in vitro findings and to identify nearly 500 other proteins that interact withS. aureusin vivo. The data presented here provide novel insights into the host-pathogen interactions that occur whenS. aureusenters the airway.
Toll-Like Receptor 5-Deficient Mice Have Dysregulated Intestinal Gene Expression and Nonspecific Resistance to
Salmonella
-Induced Typhoid-Like Disease
Authors: Vijay-Kumar Matam , Aitken Jesse D. , Kumar Amrita , Neish Andrew S. , Uematsu Satoshi , Akira Shizuo , Gewirtz Andrew T.
Published: January 2008

The recognition of flagellin by Toll-like receptor 5 (TLR5) is the dominant means by which model intestinal epithelia activate proinflammatory gene expression in response to
Salmonella enterica
. The role of the flagellin-TLR5 interaction in vivo has been addressed primarily via studies that use flagellar mutants. Such studies suggest that host recognition of flagellin promotes rapid neutrophil recruitment that protects the host from this pathogen. However, these works do not directly address the role of TLR5 and are subject to the caveat that flagellar mutations may broadly affect
Salmonella
gene expression. Thus, we examined the role of the flagellin-TLR5 interaction via the use of TLR5-deficient (TLR5KO) mice. We utilized both the traditional model of murine
Salmonella
infection, wherein low-dose oral infection of mice with
Salmonella enterica
subsp.
enterica
serovar Typhimurium results in systemic typhoid-like disease, and a more recently characterized model in which mice are pretreated with streptomycin to result in gut-restricted acute enteritis. In the enteritis model, TLR5KO mice had more severe gut pathology, thus “phenocopying” previous results obtained with
Salmonella
mutants. In contrast, TLR5KO mice were resistant to
Salmonella
-induced typhoid-like disease. However, such resistance was not specific for flagellated serovar Typhimurium, but rather, TLR5KO mice were also resistant to challenges by flagellin-deficient serovar Typhimurium. Such resistance associated with elevations in the microbiota was ablated by antibiotic pretreatment and correlated with basal elevations in intestinal host defense gene expression. All together, these results indicate that the resistance of TLR5KO mice to
Salmonella
-induced typhoid-like illness resulted from alterations in their basal phenotype rather than from the lack of TLR5 ligation during the infection per se.
SHARING SECRETS USING ELEMENTARY CELLULAR AUTOMATA
Authors: DEL REY A. MARTÍN , SÁNCHEZ G. RODRÍGUEZ
Published: January 2008

In this paper, a new cryptographic protocol to securely share a secret among a set of participants is presented. It is based on the use of non-reversible elementary cellular automata with rule numbers 90 and 150. The protocol is shown to be perfect and ideal.
MULTIPARTY QUANTUM STATE SHARING OF m-QUBIT STATE
Authors: DONG LI , XIU XIAOMING , GAO YAJUN
Published: January 2008

A scheme for quantum state sharing (QSTS) of a one-particle state is proposed for a three-particle GHZ state utilized as a quantum channel. After the sender (Alice) makes Bell-state measurements (BM) on her particles, and the controller (Charlie) performs a computational basis measurement (CM), the recipient (Bob) only needs to carry out a unitary transformation of the classical information from the sender and the controller. Finally, the scheme is generalized to multiparty QSTS of a one-qubit state with n agents and an m-qubit state with n agents.
SIMULATION OF DEMOGRAPHIC CHANGE IN PALESTINIAN TERRITORIES
Authors: SUMOUR M. A. , El-ASTAL A. H. , SHABAT M. M. , RADWAN M. A.
Published: January 2008

Mortality, birth rates and retirement play a major role in demographic changes. In most cases, mortality rates decreased in the past century without noticeable decrease in fertility rates, leading to a significant increase in population growth. In many poor countries like Palestinian Territories the number of births has fallen and the life expectancy increased.

In this paper we concentrate on measuring, analyzing and extrapolating the age structure in Palestine a few decades ago into the future. A Fortran program has been designed and used for the simulation and analysis of our statistical data. This study of demographic change in Palestine has shown that Palestinians will have in future problems as the strongest age cohorts are the above-60-year olds. We therefore recommend the increase of both the retirement age and female employment.
NUMERICAL METHODS FOR SOLVING THE RELATIVISTIC OPPENHEIMER–VOLKOFF EQUATIONS
Authors: PAPASOTIRIOU P. J. , GEROYANNIS V. S. , SANIDAS S. A.
Published: January 2008

In this paper, three methods for computing non-rotating neutron star models are discussed. The relativistic Oppenheimer–Volkoff (OV) equations of hydrostatic equilibrium are solved using (a) the well-known variable step method, (b) a method based on a modified form of the OV equations, where the thermodynamic enthalpy function is the independent variable, and (c) a new straightforward method, based on the ODEPACK Fortran package for solving systems of differential equations. We present results concerning several equations of state and conclusions concerning the applicability of each method.
DYNAMICS AND STRUCTURE OF THE MAIN ITALIAN COMPANIES
Authors: BRIDA JUAN GABRIEL , RISSO WISTON ADRIAN
Published: January 2008

Financial markets can be modeled as complex systems. The Hugh quantity and different information affecting these markets is a remarked characteristic. However some of this information can be recovered by constructing a topology of the market. We develop a symbolic method in order to study relationships in the financial markets by constructing a minimal spanning tree (MST) and a hierarchical tree (HT). The method is successfully applied to the Italian financial market, detecting clusters with economic sense. This classification is helpful in portfolio construction and studying industrial networks.
WHORLED PATTERNS OF PHYLLOTAXIS
Authors: LIU RUEY-TARNG , LIAW SY-SANG
Published: January 2008

Much research has shown that phyllotactic patterns can be considered as resulting from a growth process. A simple inhibition mechanism is used to generate automatically the spiral patterns and the magic Fibonacci numbers. We constrain the mechanism by introducing the requirement of the threshold energy-rate in producing primordia. With this modification, we are able to generate not only spiral but also whorled patterns. Our model can yield various possibilities of the whorled patterns observed in plants.
PIECEWISE CONSTANT SWITCHED DYNAMICAL SYSTEMS IN POWER ELECTRONICS
Authors: SAITO TOSHIMICHI , KABE TAKAHIRO , ISHIKAWA YUKI , MATSUOKA YUSUKE , TORIKAI HIROYUKI
Published: January 2008

This paper overviews nonlinear dynamics of switching power converters which are common objects in dynamical system theory and power electronics. First, complex dynamics of single switching power converters is discussed. Their nonlinear switching can cause rich chaotic and bifurcation phenomena including complicated superstable periodic behavior in discontinuous conduction mode. Second, paralleled converters with winner-take-all switching is discussed. This system can realize multiphase synchronization relating to current sharing with smaller ripple for low-voltage high-current capabilities. Analysis of the dynamics is performed through simple models having piecewise constant vector field and piecewise linear trajectories. Third, simple hardware implementation method is shown and typical phenomena are confirmed experimentally. Finally some future problems are discussed.
APERIODIC NONCHAOTIC ATTRACTORS, STRANGE AND OTHERWISE
Authors: PRASAD AWADHESH , NANDI AMITABHA , RAMASWAMY RAMAKRISHNA
Published: January 2008

The main conceptual issues in the study of strange nonchaotic dynamics have been summarized and reviewed earlier [Prasad et al., 2001]. In the past five years, there has been further progress in the analysis of such attractors, and in understanding the nature of dynamical transitions in quasiperiodically forced systems. Here we discuss new developments which include the creation of strange nonchaotic attractors in excitable systems, the elucidation of the mechanisms for the intermittent and fractalization routes to SNA as well as their potential applications. The possibility of creating such attractors without recourse to quasiperiodic forcing is an important objective, and this has been realized in specific circumstances.
SPECIAL PROPERTIES OF IMAGES AND CORRESPONDING SIGNALS GENERATED BY CHEMICAL REACTIONS DISCRETE CHAOTIC DYNAMICS
Authors: GONTAR V. , GRECHKO O.
Published: January 2008

A system of difference equations derived from chemical reactions discrete chaotic dynamics (DCD) is used to generate different types of images and corresponding discrete time series (signals). Dynamic properties of the generated time series and images are illustrated by partial bifurcation diagrams, partial intermediate bifurcation diagrams and Lyapunov exponents. Examples of images and signals have been presented. Some special relations between images and signals generated by DCD have been established and discussed.
MEASURING SYNCHRONIZATION WITH NONLINEAR EXCITABLE MEDIA
Authors: CHERNIHOVSKYI ANTON , LEHNERTZ KLAUS
Published: January 2008

We examine a possible utilization of the recently proposed method of signal-induced excitation waves in nonlinear excitable media as a means for the noise-tolerant detection of zero-lag phase synchronization in very noisy time series. We show that in cases, where a relatively strong noise contamination aggravates the direct application of phase-based measures of synchronization, it is nevertheless possible to detect synchronization phenomena.
BURSTING NEAR HOMOCLINIC BIFURCATION IN TWO COUPLED CHUA OSCILLATORS
Authors: DANA SYAMAL KUMAR , ROY PRODYOT KUMAR
Published: January 2008

We report experimental observation of cycle-cycle bursting near homoclinic bifurcation in a self-oscillating Chua oscillator when it is diffusively coupled to another excitable Chua oscillator. The excitable oscillator induces an asymmetry in the self-oscillating Chua oscillator via coupling. The coupling strength controls the strength of the asymmetry that plays a key role in transition to bursting near homoclinic bifurcation.
FORMING PULSES IN NONAUTONOMOUS CHAOTIC OSCILLATOR
Authors: DMITRIEV ALEXANDER , EFREMOVA ELENA , KUZMIN LEV , ATANOV NIKOLAY
Published: January 2008

In this work we demonstrate a possibility of generating chaotic pulses by means of parameter modulation of chaotic oscillator. Chaotic oscillator with 2.5 degrees of freedom and transistor as an active element is taken as a model. It is shown that periodic stimulation of such system allows to generate chaotic pulse stream, the duration of chaotic pulses and their duty cycle can be widely varied by suitable choice of frequency of the exciting force and bias voltage.
TWO-SCROLL ATTRACTOR IN A DELAY DYNAMICAL SYSTEM
Authors: TAMAŠEVIČIUS ARŪNAS , PYRAGIENĖ TATJANA , MEŠKAUSKAS MANTAS
Published: January 2008

Nonvanishing 𐑍-shaped nonlinear function has been introduced in delay dynamical system instead of commonly used Mackey–Glass type function. Depending on time delay the system exhibits not only mono-scroll, but also more complex two-scroll hyperchaotic attractors. Delay system with the novel nonlinear function can be implemented as an analogue electronic oscillator.
MINIMIZING STOCHASTICITY IN THE NAO INDEX
Authors: LIND PEDRO G. , MORA ALEJANDRO , HAASE MARIA , GALLAS JASON A. C.
Published: January 2008

We show that the monthly North Atlantic Oscillation index routinely used in climatology as an indicator for global climate variability is not an optimal choice. A critical Markov analysis of the two pressure time-series for both, monthly and daily NAO index, indicates that the monthly index, due to its low sampling rate, contains higher stochastic terms than the daily index. Applying a recently developed variationally optimized Markov analysis leads to a new NAO index with minimal stochasticity.
RECURRENCE QUANTIFICATIONS: FEATURE EXTRACTIONS FROM RECURRENCE PLOTS
Authors: WEBBER CHARLES L. , ZBILUT JOSEPH P.
Published: January 2008

Recurrence plots are two-dimensional representations of multidimensional dynamics captured by applying time delays to a single series (vector) of ordinal data in time or space. Recurrence plots may be presented with beautiful lace-like structures, but most important is the inference these patterns make about the underlying dynamics. Complex patterns in recurrence plots can be reduced to primary diagonal, vertical and horizontal dot patterns aligned on a grid. It is the mixing and matching of these primary structures that give rise to all derivative graphical complexities. Once strict definitions are in place, features are easily quantified from recurrence plots of any form including cross recurrence plots.
EIGENVALUE DECOMPOSITION AS A GENERALIZED SYNCHRONIZATION CLUSTER ANALYSIS
Authors: ALLEFELD CARSTEN , MÜLLER MARKUS , KURTHS JÜRGEN
Published: January 2008

Motivated by the recent demonstration of its use as a tool for the detection and characterization of phase-shape correlations in multivariate time series, we show that eigenvalue decomposition can also be applied to a matrix of indices of bivariate phase synchronization strength. The resulting method is able to identify clusters of synchronized oscillators, and to quantify their strength as well as the degree of involvement of an oscillator in a cluster. Since for the case of a single cluster the method gives similar results as our previous approach, it can be seen as a generalized Synchronization Cluster Analysis, extending its field of application to more complex situations. The performance of the method is tested by applying it to simulation data.
ELECTRONIC DESIGN OF SYNTHETIC GENETIC NETWORKS
Authors: BULDÚ JAVIER M. , GARCÍA-OJALVO JORDI , WAGEMAKERS ALEXANDRE , SANJUÁN MIGUEL A. F.
Published: January 2008

We propose the use of nonlinear electronic circuits to study synthetic gene regulation networks. Specifically, we have designed two electronic versions of a synthetic genetic clock, known as the "repressilator," making use of appropriate electronic elements linked in the same way as the original biochemical system. We study the effects of coupling in a population of electronic repressilators, with the aim of observing coherent oscillations of the whole population. With these results, we show that this kind of nonlinear circuits can be helpful in the design and understanding of synthetic genetic networks.
GENERAL COUPLING FOR MUTUAL SYNCHRONIZATION OF THREE IDENTICAL OSCILLATORS
Authors: GROSU IOAN
Published: January 2008

A general coupling between three arbitrary identical oscillators is proposed and the synchronization is analytically proved. Numerical results are given for a system that needs the simplest coupling.
FORCED SYNCHRONIZATION IN MORRIS–LECAR NEURONS
Authors: KITAJIMA HIROYUKI , KURTHS JÜRGEN
Published: January 2008

We investigate forced synchronization between electrically coupled Morris–Lecar neurons with class I and class II excitability through numerical bifurcation analysis. We find that class II neurons have wider parameter regions of forced synchronization. However, the bifurcation structure and patterns of spikes for class II are complicated; there exist period-doubling bifurcations, interesting two-periodic oscillations and irregular bursting spikes with high values of the coefficient of variation of the interspike interval.
EXPERIMENTS ON AN ELECTRICAL NONLINEAR OSCILLATORS NETWORK
Authors: MORFU S. , BOSSU J. , MARQUIÉ P.
Published: January 2008

We have recently proposed a Cellular Nonlinear Network (CNN) based on nonlinear oscillator properties to perform image processing tasks. We present here the electronic implementation of the elementary cell of this CNN. We experimentally verify the main property of the CNN, that is the possibility to enhance a weak difference of initial condition between two specific cells of the CNN at a given time. For this optimal time, a contrast enhancement of a weak contrasted gray scale is possible.
MEASURING SYNCHRONIZATION IN THE EPILEPTIC BRAIN: A COMPARISON OF DIFFERENT APPROACHES
Authors: OSTERHAGE HANNES , MORMANN FLORIAN , STANIEK MATTHÄUS , LEHNERTZ KLAUS
Published: January 2008

We investigate the relative merit of different linear and nonlinear synchronization measures for a characterization of the spatio-temporal dynamics of the epileptic process. Analyzing long-lasting multichannel electroencephalographic recordings from more than 20 epilepsy patients we show that all measures are able to identify brain regions of pathological synchronization associated with epilepsy, even during the seizure-free interval, and are able to detect a long-lasting transitional preseizure state. These findings render synchronization measures attractive for future prospective studies on seizure prediction.
SYNCHRONIZATION PHENOMENA IN VAN DER POL OSCILLATORS COUPLED BY A TIME-VARYING RESISTOR
Authors: UWATE YOKO , NISHIO YOSHIFUMI
Published: January 2008

In this study, synchronization phenomena observed in van der Pol oscillators coupled by a time-varying resistor are investigated. We realize the time-varying resistor by switching a positive and a negative resistor periodically. By carrying out circuit experiments and computer calculations, interesting synchronization phenomena can be confirmed to be generated in this system. Namely, the synchronization states change according to the switching frequency of the time-varying resistor.
HIERARCHICAL MODELING OF A FORCED ROBERTS DYNAMO
Authors: DONNER REIK , FEUDEL FRED , SEEHAFER NORBERT , SANJUÁN MIGUEL A. F.
Published: January 2008

We investigate the dynamo effect in a flow configuration introduced by G. O. Roberts in 1972. Based on a clear energetic hierarchy of Fourier components on the steady-state dynamo branch, an approximate model of interacting modes is constructed covering all essential features of the complete system but allowing simulations with a minimum amount of computation time. We use this model to study the excitation mechanism of the dynamo, the transition from stationary to time-dependent dynamo solutions and the characteristic properties of the latter ones.
TIME DOMAIN DIAKOPTIC ANALYSIS BASED ON REDUCED-ORDER STATE EQUATIONS
Authors: IORDACHE MIHAI , DUMITRIU LUCIA
Published: January 2008

In this paper we present some new tearing techniques to systematically formulate the state equations in symbolic normal-form for linear and/or nonlinear time-invariant large-scale analog circuits. The excess elements of the first and of the second kind are unitarily treated in order to allow a symbolic representation of the circuit with a minimum number of state variables. A procedure to reduce the state equation number of each subcircuit is also presented. The reduced-order is based on an implicit integration algorithm and on the successive elimination of the selected state variables. Examples are given to illustrate the decomposition procedure, the assignment of the connection sources and the reduced-order technique.
NUMERICAL TREATMENT OF EDUCATIONAL CHAOS OSCILLATOR
Authors: TAMAŠEVIČIUS ARÜNAS , PYRAGIENĖ TATJANA , PYRAGAS KȨSTUTIS , BUMELIENĖ SKAIDRA , MEŠKAUSKAS MANTAS
Published: January 2008

A mathematical model of a recently suggested chaos oscillator for educational purposes is treated and numerical results are presented. Bifurcation diagrams, phase portraits, power spectra, Lyapunov exponents are simulated. In addition, the Feigenbaum number is estimated.
FRACTAL DISTRIBUTION OF REVERSE ITERATIONS IN MAPS WITH CHAOTIC DYNAMICS
Authors: TOMASHEVSKIY ALEXEY , KAPRANOV MICHAEL
Published: January 2008

The features of processes of chaotic discrete map in reverse time are considered. The fractal distribution of reverse iteration points is indicated. The approach to investigating reverse points manifold based on special ordering methods is proposed.
A WAVELET TRANSFER MODEL FOR TIME SERIES FORECASTING
Authors: FAY DAMIEN , RINGWOOD JOHN
Published: January 2008

This paper is concerned with the case of an exogenous system in which a model is required to forecast a periodic output time series using a causal input. A novel approach is developed in which the wavelet packet transform is taken of both the dependent time series and causal input. This results in two sets of basis dictionaries and requires two bases to be chosen. It is proposed that the best bases to choose are those which maximize the mutual information. Input selection is then implemented by eliminating those coefficients of the selected input basis with low mutual information. As an example, a model is constructed to forecast short-term electrical demand.
TIME SERIES ANALYSIS OF ECG: A POSSIBILITY OF THE INITIAL DIAGNOSTICS
Authors: LOSKUTOV ALEXANDER , MIRONYUK OLGA
Published: January 2008

The methods of nonlinear dynamics are applied to reveal the pathologies of patients with different heart failures. Our approach is based on the analysis of the correlation and embedding dimensions of the RR-intervals of ECGs. We demonstrate that these characteristics are quite convenient tools for the initial diagnosis. Advantages and disadvantages of the method are discussed.
ANALOGUE SIGNAL PREDICTOR: FREQUENCY-DOMAIN ANALYSIS
Authors: MEŠKAUSKAS MANTAS , TAMAŠEVIČIUS ARŪNAS , PYRAGAS KȨSTUTIS
Published: January 2008

Frequency-domain analysis of the recently suggested analogue signal predictor is performed. In addition, the operation of the circuit is demonstrated in the high frequency and very high frequency ranges by means of PSPICE simulator employing high-speed operational amplifiers.
EFFECT OF NOISE AND STRUCTURAL INHOMOGENEITIES IN REACTION–DIFFUSION MEDIA
Authors: MORFU S. , MARQUIÉ P.
Published: January 2008

We investigate the pinning and depinning condition of a kink in both homogeneous and inhomogeneous reaction–diffusion media. We show that structural inhomogeneities hinder information propagation whereas noise enhances propagation.
RECURRENCE QUANTIFICATION ANALYSIS OF ELECTROCHEMICAL NOISE DATA DURING PIT DEVELOPMENT
Authors: MONTALBÁN LUIS SANTOS , HENTTU PÄIVI , PICHÉ ROBERT
Published: January 2008

Electrochemical noise (EN) data is commonly used to monitor corrosion of metals in various environments. In this work we use recurrence quantification analysis (RQA) to study EN time series of stainless steel AISI 316 samples immersed in a mildly corrosive electrolyte. It is found that RQA of current and potential time series reveal different information: current time series provides detailed information on the kinetics of the pitting corrosion process, while the potential time series identifies the transitions from one thermodynamic state to another in the pitting corrosion process.
PARAMETER SELECTION FOR PERMUTATION ENTROPY MEASUREMENTS
Authors: STANIEK MATTHÄUS , LEHNERTZ KLAUS
Published: January 2008

We investigate the applicability of the permutation entropy H and a synchronization index γ that is based on the changing tendency of temporal permutation entropies to analyze noisy time series from nonstationary dynamical systems with poorly understood properties. Using model systems, we first study the interdependencies of parameters involved in the calculation of both measures. Having identified appropriate parameter settings we then analyze long-lasting EEG time series recorded from an epilepsy patient. Our findings indicate that γ could be of interest for studies on the predictability of epileptic seizures.
DETECTING COUPLING DIRECTIONS IN MULTIVARIATE OSCILLATORY SYSTEMS
Authors: WINTERHALDER MATTHIAS , SCHELTER BJÖRN , TIMMER JENS
Published: January 2008

Determination of synchronization phenomena between pairs of coupled multivariate processes is of particular interest in Nonlinear Dynamics. Besides synchronization phenomena, coupling directions between the processes are investigated. We present an approach to analyze coupling directions in multivariate oscillatory stochastic systems. We propose usage of partial directed coherence developed in the framework of linear stochastic processes. We show that partial directed coherence is also applicable to detect coupling directions in nonlinear systems such as coupled stochastic van der Pol and stochastic Rössler systems. Furthermore, a differentiation between direct and indirect couplings in multivariate systems is possible when applying partial directed coherence.
TERRAIN CLASSIFICATION USING 3D CO-OCCURRENCE FEATURES AND NEURAL NETWORKS
Authors: WOO DONG-MIN , PARK DONG-CHUL , NGUYEN QUOC-DAT
Published: January 2008

Texture analysis has been efficiently utilized in the area of terrain classification. In this application, features have been obtained in the 2D image domain. In this paper we suggest 3D co-occurrence texture features by extending the concept of co-occurrence feature to the 3D world. The suggested 3D features are described as a 3D co-occurrence matrix by using a co-occurrence histogram of digital elevations at two contiguous positions. The practical construction of the co-occurrence matrix limits the number of levels of digital elevation. If the digital elevation is quantized into a few levels over the whole DEM (Digital Elevation Map), distinctive features cannot be obtained. To resolve this quantization problem, we employ the local quantization technique which can preserve the variation of elevations with a small number of quantization levels. SOM (Self-Organizing Maps), FCM (Fuzzy C-mean) and GBFCM (Gradient Based Fuzzy C-mean) clustering algorithms are employed to implement the terrain classifier, since these ANN clustering algorithms are known as robust against the high dimensionality problem in the classification process. Experimental results show that the classification accuracy with the addition of 3D co-occurrence features is significantly improved over the conventional classification method only with 2D features.
REAL-TIME FIRE AND SMOKE DETECTION USING CAMERA SEQUENCE IMAGE IN TUNNEL ENVIRONMENT
Authors: LEE BYOUNGMOO , HAN DONGIL
Published: January 2008

In this paper, we proposed an image processing technique for automatic real time fire and smoke detection in tunnel environment. To avoid the large scale of damage of fire occurring in the tunnel, it is necessary to have a system to sense and minimize the incident as fast as possible. However it is impossible for human observation of Closed-Circuit Television (CCTV) in tunnel for 24 h. So if the fire and smoke detection system through image processing can warn a fire, it will be very convenient, and it can be possible to minimize damage even when no one is in front of the monitor. The fire and smoke detection is different from forest fire detection as there are elements such as car and tunnel lights and others that are different from the forest environment so an indigenous algorithm has to be developed. The two algorithms proposed in this paper are able to detect the exact position at the earlier stage of incident. In addition, by comparing properties of each algorithm throughout experiment, we have proved the validity and efficiency of proposed algorithm.
PERFORMANCE EVALUATION OF DIFFERENT WEIGHTING SCHEMES ON KNN-BASED EMOTION RECOGNITION IN MANDARIN SPEECH
Authors: PAO TSANG-LONG , CHENG YUN-MAW , CHEN YU-TE , YEH JUN-HENG
Published: January 2008

Since emotion is important in influencing cognition, perception of daily activities such as learning, communication and even rational decision-making, it must be considered in human-computer interaction. In this paper, we compare four different weighting functions in weighted KNN-based classifiers to recognize five emotions, including anger, happiness, sadness, neutral and boredom, from Mandarin emotional speech. The classifiers studied include weighted KNN, weighted CAP, and weighted D-KNN. We use the result of traditional KNN classifier as the line performance measure. The experimental results show that the used Fibonacci weighting function outperforms others in all weighted classifiers. The highest accuracy achieves 81.4% with weighted D-KNN classifier.
AN EN-ROUTE FILTERING METHOD IN SENSOR NETWORKS USING DECISION FUNCTION
Authors: KIM MUN SU , CHO TAE HO
Published: January 2008

Security in sensor networks is a major issue. Sensor networks use symmetric cryptography protocol since sensor nodes have resource constrained hardware. Such netowrks are also deployed in hostile environments. Therefore, an attacker can get all information after any nodes get compromised. The adversary can inject false sensing reports or false Message Authentication Codes into real reports. A probabilistic voting-based filtering scheme is proposed but in several cases it is inefficient in terms of energy consumption and filtering effectiveness. We proposed a new method that uses a decision function regardless of whether each forwarding node executes a verification process. Through performance analysis and simulation, our result shows that the proposed method is much more efficient than the probabilistic voting-based scheme in many cases.
Is polycystic ovary syndrome associated with high sympathetic nerve activity and size at birth?
Authors: Sverrisdóttir Yrsa Bergmann , Mogren Tove , Kataoka Josefin , Janson Per Olof , Stener-Victorin Elisabet
Published: January 2008

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disturbance among women of reproductive age and is proposed to be linked with size at birth and increased prevalence of cardiovascular disease. A disturbance in the sympathetic nervous system may contribute to the etiology of PCOS. This study evaluates sympathetic outflow in PCOS and its relation to size at birth. Directly recorded sympathetic nerve activity to the muscle vascular bed (MSNA) was obtained in 20 women with PCOS and in 18 matched controls. Ovarian ultrasonographic evaluation, biometric, hormonal, and biochemical parameters were measured, and birth data were collected. Women with PCOS had increased MSNA (30 ± 8 vs. 20 ± 7 burst frequency, P < 0.0005) compared with controls. MSNA was positively related to testosterone ( r = 0.63, P < 0.005) and cholesterol ( r = 0.55, P = 0.01) levels in PCOS, which, in turn, were not related to each other. Testosterone level was a stronger predictor of MSNA than cholesterol. Birth size did not differ between the study groups. This is the first study to directly address sympathetic nerve activity in women with PCOS and shows that PCOS is associated with high MSNA. Testosterone and cholesterol levels are identified as independent predictors of MSNA in PCOS, although testosterone has a stronger impact. The increased MSNA in PCOS may contribute to the increased cardiovascular risk and etiology of the condition. In this study, PCOS was not related to size at birth.
Randomized Double-Blind Trial of Darbepoetin Alfa in Patients With Symptomatic Heart Failure and Anemia
Authors: Ghali Jalal K. , Anand Inder S. , Abraham William T. , Fonarow Gregg C. , Greenberg Barry , Krum Henry , Massie Barry M. , Wasserman Scott M. , Trotman Marie-Louise , Sun Yan , Knusel Beat , Armstrong Paul
Published: January 2008

Background—

Substantial evidence suggests that anemia is an independent risk factor for worse outcomes in patients with heart failure (HF). The Study of Anemia in Heart Failure Trial (STAMINA-HeFT) is the largest multicenter, randomized, double-blind, placebo-controlled trial to date evaluating the effect of treating anemia in HF.

Methods and Results—

Patients (N=319) with symptomatic HF, left ventricular ejection fraction ≤40%, and hemoglobin ≥9.0 g/dL and ≤12.5 g/dL were randomized (double-blind) to placebo (N=157) or darbepoetin alfa (N=162) subcutaneously every 2 weeks for 1 year (target hemoglobin, 14.0±1.0 g/dL). The primary end point was change from baseline to week 27 in treadmill exercise time. Secondary end points were change from baseline in New York Heart Association class and quality of life at week 27. An additional prespecified efficacy analysis included the time to death by any cause or first HF-related hospitalization by 1 year. At baseline, the median (interquartile range) hemoglobin was 11.4 (10.9, 12.0) g/dL. At week 27, darbepoetin alfa treatment increased median (interquartile range) hemoglobin by 1.8 (1.1, 2.5) g/dL (placebo, 0.3 [−0.2, 1.0] g/dL;
P
<0.001). Of the patients treated with darbepoetin alfa, 85% achieved 2 consecutive hemoglobin levels of 14.0±1.0 g/dL during the study and experienced a hemoglobin increase of ≥1.0 g/dL from baseline. By intent-to-treat analysis, darbepoetin alfa treatment did not significantly improve exercise duration, New York Heart Association class, or quality of life score compared with placebo. A nonsignificant trend was observed toward a lower risk of all-cause mortality or first HF hospitalization in darbepoetin alfa–treated patients compared with placebo (hazard ratio, 0.68; 95% CI, 0.43, 1.08;
P
=0.10). Occurrences of adverse events were similar in both treatment groups.

Conclusions—

In this study of patients with symptomatic HF and anemia, treatment with darbepoetin alfa was not associated with significant clinical benefits. Darbepoetin alfa treatment was well tolerated and effectively raised hemoglobin. A trend of lower risk of morbidity and mortality was observed.