bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibitory modulation of distal C‐terminal on protein kinase C‐dependent phospho‐regulation of rat TRPV1 receptors
Authors: Liu Beiying , Ma Weijun , Ryu Sujung , Qin Feng
Published: September 2004

The vanilloid receptor TRPV1, previously known as VR1, has been implicated in pain sensation under both physiological and pathological conditions. The channel is highly expressed in sensory ganglion neurones and is activated by a range of noxious stimuli including irritant chemicals, acids and heat. In order to understand the structural basis underlying this polymodal activation and the regulation by intracellular signalling pathways, we have investigated the functional roles of the cytoplasmic C‐terminal of rat TRPV1. A mutant with the maximal truncation of the distal C‐terminal encompassing the last 88 residues was constructed. Of interest, this mutant exhibited a Ca2+‐dependent functional loss; it was irresponsive to capsaicin in the presence of extracellular Ca2+, but fully functional otherwise. Further studies of this construct revealed that extracellular Ca2+ alone could activate the channel, and that the activation required protein kinase C (PKC) phosphorylation at S502, an event that was up‐regulated by external Ca2+ entry. We compared the truncation mutant with wild‐type TRPV1 and demonstrated that it had a significantly increased sensitivity to PKC phosphorylation. These results suggest the distal C‐terminal of TRPV1 can inhibit phosphorylation‐induced potentiation of the wild‐type channel. They also call into question some established functions of the distal C‐terminal of TRPV1, including its roles in agonist binding and functional desensitization. We suggest that the functional loss of the truncation mutant, in the presence of extracellular Ca2+, was not due to disruption of agonist binding or gating, but rather to desensitization promoted by unstimulated extracellular Ca2+ entry.
Treatment with leuprolide acetate decreases the threshold of the ventilatory response to carbon dioxide in healthy males
Authors: Mateika Jason H. , Omran Qasim , Rowley J. A. , Zhou X. S. , Diamond M. P. , Badr M. Safwan
Published: September 2004

This investigation was designed to determine if suppression of testosterone alters the ventilatory response to carbon dioxide in the presence of high and low levels of oxygen. Eleven healthy male subjects completed a series of rebreathing trials during wakefulness, before and after treatment with a long‐acting gonadotropin‐releasing hormone agonist. Five subjects also completed studies during non‐rapid eye movement (NREM) sleep. During wakefulness, subjects initially hyperventilated to reduce the partial pressure of carbon dioxide (PET,CO2) below 25 Torr. Subjects then rebreathed from a bag containing a normocapnic (42 Torr), low (50 Torr) or high oxygen (140 Torr) gas mixture. During each trial PET,CO2 increased while oxygen was maintained at a constant level. The threshold of the ventilatory response to carbon dioxide was considered to be the point at which minute ventilation began to rise in a linear fashion as PET,CO2 increased. The slope of the ventilatory response above the threshold was used as a measure of sensitivity to carbon dioxide. During NREM sleep, hypocapnia was induced via nasal mechanical ventilation. Several trials were completed until the cessation of mechanical ventilation resulted in a central apnoea which demarcated the threshold of the ventilatory response to carbon dioxide. In response to treatment with leuprolide acetate, the threshold measured in wakefulness decreased during carbon dioxide rebreathing in the presence of low (41.05 ± 0.77 versus 39.40 ± 0.83 Torr; P= 0.01) and high (46.32 ± 0.56 versus 44.78 ± 0.83 Torr; P= 0.01) oxygen levels. An increase in sensitivity (4.82 ± 0.61 versus 7.17 ± 1.20 l min−1 Torr−1; P= 0.02) was also observed during rebreathing in the presence of high but not low oxygen levels. The increase in sensitivity was accompanied by an increase in carbon dioxide production. The findings observed during NREM sleep were similar to those observed during wakefulness, since the PET,CO2 that demarcated the threshold was decreased after leuprolide treatment (42.1 ± 0.6 versus 39.6 ± 0.6 Torr; P= 0.002). Additionally, the decrease in PET,CO2 required to induce an apnoea was greater after treatment with leuprolide (2.56 ± 0.25 versus 4.06 ± 0.29 Torr; P= 0.004). We conclude that suppression of testosterone decreases the threshold of the ventilatory response to carbon dioxide during both wakefulness and sleep.
Abnormal Cytokinesis in Cells Deficient in the Breast Cancer Susceptibility Protein BRCA2
Authors: Daniels Matthew J. , Wang Yunmei , Lee MiYoung , Venkitaraman Ashok R.
Published: September 2004

Germ-line mutations inactivating
BRCA2
predispose to cancer. BRCA2-deficient cells exhibit alterations in chromosome number (aneuploidy), as well as structurally aberrant chromosomes. Here, we show that BRCA2 deficiency impairs the completion of cell division by cytokinesis. BRCA2 inactivation in murine embryo fibroblasts (MEFs) and HeLa cells by targeted gene disruption or RNA interference delays and prevents cell cleavage. Impeded cell separation is accompanied by abnormalities in myosin II organization during the late stages in cytokinesis. BRCA2 may have a role in regulating these events, as it localizes to the cytokinetic midbody. Our findings thus link cytokinetic abnormalities to a hereditary cancer syndrome characterized by chromosomal instability and may help to explain why BRCA2-deficient tumors are frequently aneuploid.
How Do Small Water Clusters Bind an Excess Electron?
Authors: Hammer Nathan I. , Shin Joong-Won , Headrick Jeffrey M. , Diken Eric G. , Roscioli Joseph R. , Weddle Gary H. , Johnson Mark A.
Published: September 2004

The arrangement of water molecules around a hydrated electron has eluded explanation for more than 40 years. Here we report sharp vibrational bands for small gas-phase water cluster anions, (H
2
O)
4-6
–
and (D
2
O)
4-6
–
. Analysis of these bands reveals a detailed picture of the diffuse electron-binding site. The electron is closely associated with a single water molecule attached to the supporting network through a double H-bond acceptor motif. The local OH stretching bands of this molecule are dramatically distorted in the pentamer and smaller clusters because the excited vibrational levels are strongly coupled to the electron continuum. The vibration–to–electronic energy transfer rates, as revealed by line shape analysis, are mode-specific and remarkably fast, with the symmetric stretching mode surviving for less than 10 vibrational periods [50 fs in (H
2
O)
4
–
].
PchC Thioesterase Optimizes Nonribosomal Biosynthesis of the Peptide Siderophore Pyochelin in
Pseudomonas aeruginosa
Authors: Reimmann Cornelia , Patel Hiten M. , Walsh Christopher T. , Haas Dieter
Published: September 2004

In
Pseudomonas aeruginosa
, the antibiotic dihydroaeruginoate (Dha) and the siderophore pyochelin are produced from salicylate and cysteine by a thiotemplate mechanism involving the peptide synthetases PchE and PchF. A thioesterase encoded by the
pchC
gene was found to be necessary for maximal production of both Dha and pyochelin, but it was not required for Dha release from PchE and could not replace the thioesterase function specified by the C-terminal domain of PchF. In vitro, 2-aminobutyrate, a cysteine analog, was adenylated by purified PchE and PchF proteins. In vivo, this analog strongly interfered with Dha and pyochelin formation in a
pchC
deletion mutant but affected production of these metabolites only slightly in the wild type. Exogenously supplied cysteine overcame the negative effect of a
pchC
mutation to a large extent, whereas addition of salicylate did not. These data are in agreement with a role for PchC as an editing enzyme that removes wrongly charged molecules from the peptidyl carrier protein domains of PchE and PchF.
A Multifunction ABC Transporter (Opt) Contributes to Diversity of Peptide Uptake Specificity within the Genus
Lactococcus
Authors: Lamarque Mauld , Charbonnel Pascale , Aubel Dominique , Piard Jean-Christophe , Atlan Danièle , Juillard Vincent
Published: September 2004

Growth of
Lactococcus lactis
in milk depends on the utilization of extracellular peptides. Up to now, oligopeptide uptake was thought to be due only to the ABC transporter Opp. Nevertheless, analysis of several Opp-deficient
L. lactis
strains revealed the implication of a second oligopeptide ABC transporter, the so-called Opt system. Both transporters are expressed in wild-type strains such as
L. lactis
SK11 and Wg2, whereas the plasmid-free strains MG1363 and IL-1403 synthesize only Opp and Opt, respectively. The Opt system displays significant differences from the lactococcal Opp system, which made Opt much more closely related to the oligopeptide transporters of streptococci than to the lactococcal Opp system: (i) genetic organization, (ii) peptide uptake specificity, and (iii) presence of two oligopeptide-binding proteins, OptS and OptA. The fact that only OptA is required for nutrition calls into question the function of the second oligopeptide binding protein (Opts). Sequence analysis of oligopeptide-binding proteins from different bacteria prompted us to propose a classification of these proteins in three distinct groups, differentiated by the presence (or not) of precisely located extensions.
Relationships of the
Escherichia coli
O157, O111, and O55 O-Antigen Gene Clusters with Those of
Salmonella enterica
and
Citrobacter freundii
, Which Express Identical O Antigens
Authors: Samuel Gabrielle , Hogbin John-Paul , Wang Lei , Reeves Peter R.
Published: September 2004

Escherichia coli
O157,
Salmonella enterica
O30, and
Citrobacter freundii
F90 have identical O-antigen structures, as do
E. coli
O55 and
S. enterica
O50. The O-antigen gene cluster sequences for
E. coli
O157 and
E. coli
O55 have been published, and the genes necessary for O-antigen biosynthesis have been identified, although transferase genes for glycosidic linkages are only generic and have not been allocated to specific linkages. We determined sequences for
S. enterica
O30 and
C. freundii
F90 O-antigen gene clusters and compared them to the sequence of the previously described
E. coli
O157 cluster. We also determined the sequence of the
S. enterica
O50 O-antigen gene cluster and compared it to the sequence of the previously described
E. coli
O55 cluster. For both the
S. enterica
O30-
C. freundii
F90-
E. coli
O157 group and the
S. enterica
O50-
E. coli
O55 group of O antigens, the gene clusters have identical or nearly identical organizations. The two sets of gene clusters had comparable overall levels of similarity in their genes, which were lower than the levels determined for housekeeping genes for these species, which were 55 to 65% for the genes encoding glycosyltransferases and O-antigen processing proteins and 75 to 93% for the nucleotide-sugar pathway genes. Nonetheless, the similarity of the levels of divergence in the five gene clusters required us to consider the possibility that the parent gene cluster for each structure was in the common ancestor of the species and that divergence is faster than expected for the common ancestor hypothesis. We propose that the identical O-antigen gene clusters originated from a common ancestor, and we discuss some possible explanations for the increased rate of divergence that is seen in these genes.
Effect of Chemoreceptor Modification on Assembly and Activity of the Receptor-Kinase Complex in
Escherichia coli
Authors: Liberman Louisa , Berg Howard C. , Sourjik Victor
Published: September 2004

Bacterial chemoreceptors are embedded in the inner cell membrane in tight clusters. We show that changes in receptor methylation that generate large changes in kinase activity have relatively little effect on cluster morphology. Thus, changes in receptor activity do not appear to be mediated by changes in receptor-kinase assembly.
DNA Binding Activity of theEscherichia coliNitric Oxide Sensor NorR Suggests a Conserved Target Sequence in Diverse Proteobacteria
Authors: Tucker Nicholas P. , D'Autréaux Benoît , Studholme David J. , Spiro Stephen , Dixon Ray
Published: September 2004

TheEscherichia colinitric oxide sensor NorR was shown to bind to the promoter region of thenorVWtranscription unit, forming at least two distinct complexes detectable by gel retardation. Three binding sites for NorR and two integration host factor binding sites were identified in thenorR-norVintergenic region. The derived consensus sequence for NorR binding sites was used to search for novel members of theE. coliNorR regulon and to show that NorR binding sites are partially conserved in other members of the proteobacteria.
Channel-Forming (Porin) Activity in
Herpetosiphon aurantiacus
Hp a2
Authors: Harwardt Rainer , Maier Elke , Reichenbach Hans , Weckesser Jürgen , Benz Roland
Published: September 2004

Detergent extracts of cell envelopes of the gliding bacterium
Herpetosiphon aurantiacus
formed channels in lipid bilayers. Fast protein liquid chromatography across a HiTrap-Q cation-exchange column demonstrated that a 45-kDa protein forms the channel. The observation of a channel-forming protein suggests that
Herpetosiphon aurantiacus
Hp a2 has a permeability barrier on its surface.
Supervisory behaviour as a predictor of return to work in employees absent from work due to mental health problems
Authors: Nieuwenhuijsen K , Verbeek J H A M , de Boer A G E M , Blonk R W B , van Dijk F J H
Published: September 2004

Aims:To study supervisory behaviour as a predictive factor for return to work of employees absent due to mental health problems; and to explore the association between conditional factors and supervisory behaviour.

Methods:Eighty five supervisors of employees were interviewed by telephone. Questionnaires providing information on person related factors, depressive symptoms, and sickness absence were sent to the employees at baseline, three months, six months, and after one year. Three aspects of supervisory behaviour during the period of absence were measured: communication with the employee, promoting gradual return to work, and consulting of other professionals.

Results:Better communication between supervisor and employee was associated with time to full return to work in non-depressed employees. For employees with a high level of depressive symptoms, this association could not be established. Consulting other professionals more often was associated with a longer duration of the sickness absence for both full and partial return to work. If sickness absence had financial consequences for the department, the supervisor was more likely to communicate frequently with the employee. Supervisors who were responsible for return to work in their organisation were more likely to communicate better and to consult more often with other professionals.

Conclusion:Supervisors should communicate more frequently with employees during sickness absence as well as hold follow up meetings more often as this is associated with a faster return to work in those employees.
Distribution of sickness absence in the European Union countries: Table 1
Authors: Gimeno D , Benavides F G , Benach J , Amick B C
Published: September 2004

Aims:To determine the sickness absence frequency in European Union (EU) countries.

Methods:Sickness absence was measured by questionnaire using the Third European Survey on Working Conditions. Employees were considered to have sickness absence if they reported to be absent at least one day in the past 12 months because of an accident at work, work related problems, or by other health problems.

Results:Sickness absence percentages were lower in Southern European countries compared with Central and Northern European countries, and, in general, slightly higher in men than in women.

Conclusion:This is the first description of sickness absence in each of the 15 EU countries. Examination of the sickness absence patterning between EU countries could indicate countries where important lessons to reduce sickness absence are to be learned and diffused across the EU.
Silicosis prevalence and exposure-response relations in South African goldminers
Authors: Churchyard G J , Ehrlich R , teWaterNaude J M , Pemba L , Dekker K , Vermeijs M , White N , Myers J
Published: September 2004

Aims:To measure the prevalence of silicosis among black migrant contract workers on a South African goldmine and to investigate exposure-response relations with silica dust.

Methods:In a cross sectional study, 520 black goldminers (aged >37 years) were interviewed and had chest radiographs taken. Silicosis was defined as International Labour Organisation Classification radiological profusion of 1/1 or greater.

Results:Mean length of service was 21.8 years (range 6.3–34.5). The mean intensity of respirable dust exposure was 0.37 mg/m3(range 0–0.70) and of quartz 0.053 mg/m3(range 0–0.095). The prevalence of silicosis was 18.3–19.9% depending on reader. Significant trends were found between the prevalence of silicosis and length of service, mean intensity of exposure, and cumulative exposure.

Conclusion:Results confirm a large burden of silicosis among older black workers in the South African goldmining industry, which is likely to worsen as such miners spend longer periods in continuous employment in dusty jobs. An urgent need for improved dust control in the industry is indicated. If the assumption of stability of average dust concentrations on this mine over the working life of this group of workers is correct, these workers developed silicosis while exposed to a quartz concentration below the recommended occupational exposure limit (OEL) of 0.1 mg/m3. This accords with a mounting body of evidence that an OEL of 0.1 mg/m3is not protective against silicosis.
Cross-shift changes in FEV1in relation to wood dust exposure: the implications of different exposure assessment methods
Authors: Schlünssen V , Sigsgaard T , Schaumburg I , Kromhout H
Published: September 2004

Background:Exposure-response analyses in occupational studies rely on the ability to distinguish workers with regard to exposures of interest.

Aims:To evaluate different estimates of current average exposure in an exposure-response analysis on dust exposure and cross-shift decline in FEV1among woodworkers.

Methods:Personal dust samples (n = 2181) as well as data on lung function parameters were available for 1560 woodworkers from 54 furniture industries. The exposure to wood dust for each worker was calculated in eight different ways using individual measurements, group based exposure estimates, a weighted estimate of individual and group based exposure estimates, and predicted values from mixed models. Exposure-response relations on cross-shift changes in FEV1and exposure estimates were explored.

Results:A positive exposure-response relation between average dust exposure and cross-shift FEV1was shown for non-smokers only and appeared to be most pronounced among pine workers. In general, the highest slope and standard error (SE) was revealed for grouping by a combination of task and factory size, the lowest slope and SE was revealed for estimates based on individual measurements, with the weighted estimate and the predicted values in between. Grouping by quintiles of average exposure for task and factory combinations revealed low slopes and high SE, despite a high contrast.

Conclusion:For non-smokers, average dust exposure and cross-shift FEV1were associated in an exposure dependent manner, especially among pine workers. This study confirms the consequences of using different exposure assessment strategies studying exposure-response relations. It is possible to optimise exposure assessment combining information from individual and group based exposure estimates, for instance by applying predicted values from mixed effects models.
Psychological, musculoskeletal, and respiratory problems and sickness absence before and after involvement in a disaster: a longitudinal study among rescue workers: Table 1
Authors: Dirkzwager A J E , Yzermans C J , Kessels F J M
Published: September 2004

Background:On 13 May 2000 a firework depot situated in a residential area in the Netherlands exploded. Many rescue workers were involved in the aftermath of this explosion.

Aims:To examine the longitudinal course of psychological, musculoskeletal, and respiratory problems and sickness absence among rescue workers involved.

Methods:The study population was composed of 1036 rescue workers. Data on health and sickness absence both before and after the disaster were collected from the electronic database of the rescue workers’ occupational physicians. Health problems were coded according to an adapted version of the ICD-10.

Results:After the disaster a long term increase was found in psychological, musculoskeletal, and respiratory problems. Compared to six months before the disaster, the average length of sickness absence in the first half year after the disaster increased from 6.6 to 11.6 days, and decreased slowly in the following six month periods.

Conclusions:Rescue workers involved in a disaster may experience subsequent impairment in occupational functioning.
Smoothing in occupational cohort studies: an illustration based on penalised splines
Authors: Eisen E A , Agalliu I , Thurston S W , Coull B A , Checkoway H
Published: September 2004

Aims:To illustrate the contribution of smoothing methods to modelling exposure-response data, Cox models with penalised splines were used to reanalyse lung cancer risk in a cohort of workers exposed to silica in California’s diatomaceous earth industry. To encourage application of this approach, computer code is provided.

Methods:Relying on graphic plots of hazard ratios as smooth functions of exposure, the sensitivity of the curve to amount of smoothing, length of the exposure lag, and the influence of the highest exposures was evaluated. Trimming and data transformations were used to down-weight influential observations.

Results:The estimated hazard ratio increased steeply with cumulative silica exposure before flattening and then declining over the sparser regions of exposure. The curve was sensitive to changes in degrees of freedom, but insensitive to the number or location of knots. As the length of lag increased, so did the maximum hazard ratio, but the shape was similar. Deleting the two highest exposed subjects eliminated the top half of the range and allowed the hazard ratio to continue to rise. The shape of the splines suggested a parametric model with log hazard as a linear function of log transformed exposure would fit well.

Conclusions:This flexible statistical approach reduces the dependence on a priori assumptions, while pointing to a suitable parametric model if one exists. In the absence of an appropriate parametric form, however, splines can provide exposure-response information useful for aetiological research and public health intervention.
Validation of specific inhalation challenge for the diagnosis of occupational asthma due to persulphate salts
Authors: Muñoz X , Cruz M J , Orriols R , Torres F , Espuga M , Morell F
Published: September 2004

Background:The significant value of tests used to certify the diagnosis of occupational asthma due to persulphate salts remains uncertain.

Aims:To validate the specific inhalation challenge (SIC) test for the diagnosis of occupational asthma.

Methods:Eight patients with occupational asthma due to persulphate salts, eight patients with bronchial asthma who were never exposed to persulphate salts, and ten healthy subjects were studied. Clinical history taking, spirometry, bronchial challenge with methacholine, skin prick testing to common inhalant allergens and persulphate salts, total IgE levels, and SIC to potassium persulphate were carried out in all subjects. The SIC used increasing concentrations of potassium persulphate (5, 10, 15, and 30 g) mixed with 150 g of lactose. Patients tipped the mixture from one tray to another at a distance of 30 cm from the face for 10 minutes in a challenge booth.

Results:The SIC was positive in all subjects with persulphate induced asthma and in one patient with bronchial asthma who had never been exposed to persulphate salts. Sensitivity was 100% (95% CI 67.6 to 100) and specificity was 87.5% (95% CI 52.9–97.8) when patients with occupational asthma due to persulphate salts were compared with those with bronchial asthma never exposed to persulphate salts.

Conclusions:SIC to persulphate salts performed according to the protocol described appears to be useful for the diagnosis of occupational asthma secondary to inhalation of this substance.
SYNCHRONIZATION OF REGULAR AND CHAOTIC OSCILLATIONS: THE ROLE OF LOCAL DIVERGENCE AND THE SLOW PASSAGE EFFECT — A Case Study on Calcium Oscillations
Authors: PERC MATJAŽ , MARHL MARKO
Published: September 2004

In this paper, coupling properties of regular and chaotic calcium oscillations are examined. Synchronized calcium signals among coupled cells in tissue, where calcium ions were found to be one of the most important second messengers, have proven indispensable for proper and reliable functioning of living organisms. When modeling such systems, it is of particular interest to determine, which internal system properties guarantee best coupling abilities and herewith physiologically the most efficient signal transduction between cells. We found that local contractive properties of attractors in phase space, quantified by the local divergence, represent one of the crucial system properties that determine synchronization abilities of coupled regular and chaotic oscillators. In particular, parts of attractors with close to zero local divergence largely facilitate synchronization of initially unsynchronized oscillators. For bursting oscillations, this is fully in agreement with previous studies showing that synchronization abilities of bursters are closely related with the slow passage effect. We extended this concept with the help of local divergence and succeeded to apply our theory also to other oscillatory regimes, like regular spiking and complex chaotic oscillations.
EXISTENCE OF POINCARÉ MAPS IN PIECEWISE LINEAR DIFFERENTIAL SYSTEMS IN ℝN
Authors: LLIBRE JAUME , TERUEL ANTONIO E.
Published: September 2004

In this paper we present a relationship between the algebraic notion of proper system, the geometric notion of contact point and the dynamic notion of Poincaré map for piecewise linear differential systems. This allows to present sufficient conditions (which are also necessary under additional hypotheses) for the existence of Poincaré maps in piecewise linear differential systems. Moreover, an adequate parametrization of the Poincaré maps make such maps invariant under linear transformations.
CHAOS IN A NONLINEAR ANALOG COMPUTER
Authors: KIERS KEN , KLEIN TIM , KOLB JEFF , PRICE STEVE , SPROTT J. C.
Published: September 2004

We explore the chaotic behavior of a nonlinear electrical circuit constructed with simple components such as diodes and linear operational amplifiers. The circuit may be regarded as a nonlinear analog computer that gives a nearly exact solution of a particular chaotic model. Detailed comparisons between theoretical and experimental bifurcation points and power spectra yield differences of less than 1%.
HIGHER ORDER COMPLEXITY OF TIME SERIES
Authors: GU FANJI , SHEN ENHUA , MENG XIN , CAO YANG , CAI ZHIJIE
Published: September 2004

A concept of higher order complexity is proposed in this letter. If a randomness-finding complexity [Rapp & Schmah, 2000] is taken as the complexity measure, the first-order complexity is suggested to be a measure of randomness of the original time series, while the second-order complexity is a measure of its degree of nonstationarity. A different order is associated with each different aspect of complexity. Using logistic mapping repeatedly, some quasi-stationary time series were constructed, the nonstationarity degree of which could be expected theoretically. The estimation of the second-order complexity of these time series shows that the second-order complexities do reflect the degree of nonstationarity and thus can be considered as its indicator. It is also shown that the second-order complexities of the EEG signals from subjects doing mental arithmetic are significantly higher than those from subjects in deep sleep or resting with eyes closed.
ROTATION METHOD FOR RECONSTRUCTING PROCESS AND FIELD FROM IMPERFECT DATA
Authors: CHU PETER C. , IVANOV LEONID M. , MARGOLINA TATYANA M.
Published: September 2004

Reconstruction of processes and fields from noisy data is to solve a set of linear algebraic equations. Three factors affect the accuracy of reconstruction: (a) a large condition number of the coefficient matrix, (b) high noise-to-signal ratio in the source term, and (c) no a priori knowledge of noise statistics. To improve reconstruction accuracy, the set of linear algebraic equations is transformed into a new set with minimum condition number and noise-to-signal ratio using the rotation matrix. The procedure does not require any knowledge of low-order statistics of noises. Several examples including highly distorted Lorenz attractor illustrate the benefit of using this procedure.
STRUCTURALLY STABLE TWO-CELL CELLULAR NEURAL NETWORKS
Authors: ITOH MAKOTO , CHUA LEON O.
Published: September 2004

The global phase portrait of structurally stable two-cell cellular neural networks is studied. The configuration of equilibrium points, the number of limit cycles and their locations are investigated systematically.
DELAY-INDUCED BIFURCATIONS IN A NONAUTONOMOUS SYSTEM WITH DELAYED VELOCITY FEEDBACKS
Authors: XU JIAN , YU PEI
Published: September 2004

This paper investigates the bifurcations due to time delay in the feedback control system with excitation. Based on an self-sustained oscillator, the delayed velocity feedback control system is proposed. For the case without excitation, the stability of the trivial equilibrium is discussed and the condition under which the equilibrium loses its stability is obtained. This leads to a critical stability boundary where Hopf bifurcation or periodic solutions may occur. For the case with excitation, the main attention is focused on the effect of time delay on the obtained periodic solution when primary resonance occurs in the system under consideration. To this end, the control system is changed to be a functional differential equation. Functional analysis is carried out to obtain the center manifold and then a perturbation approach is used to find periodic solutions in a closed form. Moreover, the unstable regions for the limit cycles are also obtained, predicting the occurrence of some complex behaviors. Numerical simulations are employed to find the routes leading to quasi-periodic motions as the time delay is varied. It has been found that: (i) Time delay can be used to control bifurcations; and (ii) time delay can be applied to generate bifurcations. This indicates that time delay may be used as a "switch" to control or create complexity for different applications.
GLOBAL DYNAMICS OF A DUFFING OSCILLATOR WITH DELAYED DISPLACEMENT FEEDBACK
Authors: WANG HUAILEI , HU HAIYAN , WANG ZAIHUA
Published: September 2004

This paper presents a systematic study on the dynamics of a controlled Duffing oscillator with delayed displacement feedback, especially on the local bifurcations of periodic motions with respect to the time delay. The study begins with the analysis of the stability switches of the trivial equilibrium of the system with various parametric combinations and gives the critical values of time delay, where the trivial equilibrium may change its stability. It shows that as the time delay increases from zero to the positive infinity, the trivial equilibrium undergoes a different number of stability switches for different parametric combinations, and becomes unstable at last for all parametric combinations. Then, the method of multiple scales and the numerical computation method are jointly used to obtain a global diagram of local bifurcations of periodic motions with respect to the time delay for each type of parametric combinations. The diagrams indicate two kinds of local bifurcations. One is the saddle-node bifurcation and the other is the pitchfork bifurcation, of which the former means the sudden emerging of two periodic motions with different stability and the latter implies the Hopf bifurcation in the sense of dynamic bifurcation. A novel feature, referred to as the property of "periodicity in delay", is observed in the global diagrams of local bifurcations and used to justify the validity of infinite number of bifurcating branches in the bifurcation diagrams. The stability of the periodic motions is discussed not only from the high-order approximation of the asymptotic solution, but also from viewpoint of basin of attraction, which gives a good explanation for coexisting periodic motions and quasi-periodic motions, as well as an overall idea of basin of attraction. Afterwards, a conventional Poincaré section technique is used to reveal the abundant dynamic structures of a tori bifurcation sequence, which shows that the system will repeat similar quasi-periodic motions several times, with an increase of time delay, enroute to a chaotic motion. Finally, a new Poincaré section technique is proposed as a comparison with the conventional one, and the results show that the dynamical structures on the two kinds of Poincaré sections are topologically symmetric in rotation.
FIRST LYAPUNOV VALUE AND BIFURCATION BEHAVIOR OF SPECIFIC CLASS OF THREE-DIMENSIONAL SYSTEMS
Authors: NIKOLOV SVETOSLAV
Published: September 2004

This paper presents a study of the behavior of a special class of 3D dynamic systems (i.e. RHS of the third-order equation is a cubic polynomial), using Lyapunov–Andronov's theory. Considering the general case, we find a new analytical formula for the first Lyapunov's value at the boundary of stability. It enables one to study in detail the bifurcation behavior (and the route to chaos, in particular) of dynamic systems of the above type. We check the validity of our analytical results on the first Lyapunov's value by studying the route to chaos of two 3D dynamic systems with proved chaotic behavior. These are Chua's and Rucklidge's systems. Considering their route to chaos, we find new results.
LINEAR STABILITY AND HOPF BIFURCATION IN A TWO-NEURON NETWORK WITH THREE DELAYS
Authors: GUO SHANGJIANG , HUANG LIHONG , WANG LIN
Published: September 2004

Linear stability and Hopf bifurcation in a two-neuron network with three delays (one is due to the self-feedback) are investigated. Based on the normal form approach and the center manifold theory, we derive the formula to determine the direction and stability of Hopf bifurcation.
A NOVEL SWITCHED CIRCUIT FOR CHAOTIC COMMUNICATION
Authors: NG S. W. , LEE Y. S. , QIU S. S.
Published: September 2004

In this letter, the characteristics of a novel switched circuit is presented. Its pseudo chaotic signal is digitally programmable. Robust synchronization between two mismatched circuits is demonstrated by simulation results. Lastly, applications of this circuit on chaotic communication are suggested.
ENVELOPING SURFACES AND ADMISSIBLE VELOCITIES OF HEAVY RIGID BODIES
Authors: GASHENENKO IGOR N. , RICHTER PETER H.
Published: September 2004

The general Euler-Poisson problem of rigid body motion is investigated. We study the three-dimensional algebraic level surfaces of the first integrals, and their topological bifurcations. The main result of this article is an analytical and qualitatively complete description of the projections of these integral manifolds to the body-fixed space of angular velocities. We classify the possible types of these invariant sets and analyze the dependence of their topology on the parameters of the body and the constants of the first integrals. Particular emphasis is given to the enveloping surfaces of the sets of admissible angular velocities. Their pre-images in the reduced phase space induce a Heegaard splitting which lends itself for a general choice of complete Poincaré surfaces of section, irrespective of whether or not the system is integrable.
CELLULAR NEURAL NETWORKS: ASYMMETRIC SPACE-DEPENDENT TEMPLATES, MOSAIC PATTERNS, AND SPATIAL CHAOS
Authors: TURYN LARRY
Published: September 2004

We consider a Cellular Neural Network (CNN), with a bias term, on the integer lattice ℤ2in the plane ℝ2. Space-dependent, asymmetric couplings (templates) appropriate for CNN in the hexagonal lattice on ℝ2are studied. We characterize the mosaic patterns and study their spatial entropy. It appears that for this problem, asymmetry of the template has a more robust effect on the spatial entropy than does the sign of a parameter in the templates.
DYNAMICS FOR DISCRETE-TIME CELLULAR NEURAL NETWORKS
Authors: CHEN SHYAN-SHIOU , SHIH CHIH-WEN
Published: September 2004

This presentation investigates the dynamics of discrete-time cellular neural networks (DT-CNN). In contrast to classical neural networks that are mostly gradient-like systems, DT-CNN possesses both complete stability and chaotic behaviors as different parameters are considered. An energy-like function which decreases along orbits of DT-CNN as well as the existence of a globally attracting set are derived. Complete stability can then be concluded, with further analysis on the sets on which the energy function is constant. The formations of saturated stationary patterns for DT-CNN are shown to be analogous to the ones in continuous-time CNN. Thus, DT-CNN shares similar properties with continuous-time CNN. By confirming the existence of snap-back repellers, hence transversal homoclinic orbits, we also conclude that DT-CNN with certain parameters exhibits chaotic dynamics, according to the theorem by Marotto.
SYNCHRONIZATION OF LORENZ SYSTEMS VIA IMPULSIVE CONTROL AND SPORADIC COUPLING
Authors: LI K. , SOH Y. C. , LI Z. G.
Published: September 2004

In this paper, a method that combines impulsive control and sporadic coupling for the synchronization of two Lorenz systems is proposed. The time required to synchronize the Lorenz systems can be readily computed. With this scheme, the Lorenz systems can be synchronized quickly and the time interval between successive impulsive signals can be made larger. This will improve the efficiency of channel bandwidth utilization when applied to secure communications. The results obtained in this paper are very useful in the applications of chaos-based secure communication systems.
SOME NEW METHODS TO SUPPRESS CHAOS FOR A KIND OF NONLINEAR OSCILLATOR
Authors: LEUNG ANDREW Y. T. , LIU ZENGRONG
Published: September 2004

This article extends the range of applications of a previous paper [Leung & Liu, 2003]. Some new methods to suppress chaos are proposed so that the Melnikov function is modified only slightly for the easy elimination of simple zeros. The reasonability of the methods is analyzed by the previously established criteria. Some examples are also given.
MULTIPLE PERIODIC PATTERNS VIA DISCRETE NEURAL NETS WITH DELAYED FEEDBACK LOOPS
Authors: WU JIANHONG , ZHANG RUYUAN , ZOU XINGFU
Published: September 2004

We show that a discrete dynamical system with delayed arguments that describe the computational performance of a neural network with a loop structure can exhibit the coexistence of huge number of periodic solutions, and we describe the domains of attraction for the stable periodic orbits. This demonstrates a great potential of discrete time delayed neural nets with a loop structure for the purpose of storage and retrieval of periodic patterns.
A MODEL-BASED SCHEME FOR ANTICONTROL OF SOME DISCRETE-TIME CHAOTIC SYSTEMS
Authors: MORGÜL ÖMER
Published: September 2004

We consider a model-based approach for the anticontrol of some discrete-time systems. We first assume the existence of a chaotic model in an appropriate form. Then by using an appropriate control input we try to match the controlled system with the chaotic system model. We also give a procedure to generate the model chaotic systems in arbitrary dimensions. We show that with this approach, controllable systems can always be chaotified. Moreover, if the system to be controlled is stable, control input can be chosen arbitrarily small.
EVIDENCE OF THE NON-THERMAL PHASE TRANSITION IN THE EMISSION OF SLOW TARGET RESIDUE IN 28Si–AgBr INTERACTIONS AT 14.5 AGeV
Authors: GHOSH DIPAK , DEB ARGHA , BHATTACHARYYA SWARNAPRATIM , GHOSH JAYITA
Published: September 2004

This paper reports an investigation on the occurrence of the non-thermal phase transition in the target fragmentation of 28 Si – AgBr interactions at 14.5 AGeV in azimuthal angle space using the method of factorial moment. Clear evidence of the non-thermal phase transition is obtained.
TOPOLOGICAL DEFECTS IN THE SYMPLICTIC VACUUM, ANOMALOUS POSITRON PRODUCTION AND THE GRAVITATIONAL INSTANTON
Authors: EL NASCHIE M. S.
Published: September 2004

In the present paper the phenomenon of anomalous positron production is reconsidered. An explanation of the phenomenon via the complex nature of the symplictic vacuum is attempted. This is a vacuum, akin to that of Dirac's but with an additional transfinite correction and fractal fine structure. It is conjectured that not only one, but a host of highly unstable exotic particles and weakly interacting neutral bosons may be produced under certain extreme conditions, for instance a very strong electromagnetic field. It is further shown that these particles are intimately linked to the production of mini black holes via the instanton method within the VAK of vacuum fluctuation. One of the principle conclusions in the present work is that while a symmetry breaking is accompanied by the appearance of a corresponding (new) particle, a symmetry breaking of the "average" or complex "quasi" symmetry of the VAK will be logically associated with a host of (new) "quasi" particles. This may be the explanation for the experimental observations related to the said anomalous positron production.
FUSION PROCESS OF LENNARD–JONES CLUSTERS: GLOBAL MINIMA AND MAGIC NUMBERS FORMATION
Authors: SOLOV'YOV ILIA A. , SOLOV'YOV ANDREY V. , GREINER WALTER
Published: September 2004

We present a new theoretical framework for modeling the fusion process of Lennard–Jones (LJ) clusters. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system and absorbing its energy at each step, we find cluster growing paths up to the cluster size of 150 atoms. We demonstrate that in this way all known global minima structures of the LJ-clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic number sequence for the clusters of noble gas atoms and compare it with experimental observations. We report the striking correspondence of the peaks in the dependence of the second derivative of the binding energy per atom on cluster size calculated for the chain of the LJ-clusters based on the icosahedral symmetry with the peaks in the abundance mass spectra experimentally measured for the clusters of noble gas atoms. Our method serves as an efficient alternative to the global optimization techniques based on the Monte-Carlo simulations and it can be applied for the solutions of a broad variety of problems in which atomic cluster structure is important.
A MODEL ANALYSIS OF NEUTRON DISTRIBUTION OF 208Pb BASED ON THE RELATIVISTIC IMPULSE APPROXIMATION OF PROTON ELASTIC SCATTERING
Authors: KAKI K.
Published: September 2004

Tow parameters of a WoodsγSaxon form assumed for the neutron distribution of 208 Pb nucleus are determined with the reaction cross-section and the dip position of the differential cross-section. These observables are calculated based on the relativistic impulse approximation. For the proton density we take the profile obtained from the electron scattering by unfolding the proton form factor.
CALCULATION OF RESONANCES IN WEAKLY BOUND SYSTEMS
Authors: DUTTA S. K. , DAS T. K. , KHAN M. A. , CHAKRABARTI B.
Published: September 2004

We propose a new technique to calculate the position and width of weak resonant states in weakly bound systems, using isospectral potentials. A new potential is constructed which is strictly isospectral with the original one but has desirable properties which make the calculation of the resonance simpler and more accurate. The usefulness of the method is demonstrated by calculating the first 1+ resonance in 6 Li , using a three-body cluster model for the latter.
EFFECT OF COULOMB ENERGY SHIFT ON PROTON TOTAL REACTION CROSS-SECTION
Authors: MADANI JAMAL H.
Published: September 2004

In this work we study the effect of the Coulomb energy shift on proton total reaction cross-section (σ R ) at 25, 50, and 100 MeV for several nuclei in the mass region 12≤A≤208. The cross-sections are computed using the Coulomb modified Glauber model in the optical limit approximation, and the semi-phenomenological proton and neutron density distributions. We find that the Coulomb energy shift has a significant effect on the calculated σ R , and that it brings the theory quite close to the experiment.
NEUTRON AND PROTON DRIP LINES USING THE MODIFIED BETHE–WEIZSÄCKER MASS FORMULA
Authors: BASU D. N.
Published: September 2004

Proton and neutron separation energies are calculated using the extended Bethe–Weizsäcker mass formula. This modified Bethe–Weizsäcker mass formula describes minutely the positions of all the old and the new magic numbers. It accounts for the disappearance of some traditional magic numbers for neutrons and provides extra stability for some new neutron numbers. The neutron and proton drip lines are predicted using this extended Bethe–Weizsäcker mass formula. The implications of the proton drip line on the astrophysical rp-process and of the neutron drip line on the astrophysical r-process are discussed.
DEFORMED OPTICAL POTENTIAL ANALYSES FOR P+12C
Authors: YAHYA G. A.
Published: September 2004

The high energy single folding optical potential approximation is studied to calculate the differential cross-section for proton elastic scattering of 12 C at 156 MeV and 1440 MeV and 12 C for state 2+ (4.44 MeV) at 1440 MeV. A Gaussian nuclear density distribution was used for the proton and Gaussian and Brink nuclear density distributions for the 12 C target. We used the following three effects to derive twelve different methods for the central optical potential: (i) Love and Franey and the Gaussian amplitudes, with the Brink and one-term Gaussian nuclear density distributions, (ii) Pauli correlation in the Gaussian amplitude with these densities, (iii) coupling channels on the differential cross-sections in proton elastic scattering of 12 C at 1440 MeV with single channel calculations using these amplitudes, nuclear density distributions and Pauli correlation in the Gaussian amplitude. A new numerical technique was performed to solve the deformed optical potential equations using computational programs.
RELIABILITY AND REDUNDANCY APPORTIONMENT OPTIMIZATION USING INTERACTIVE PHYSICAL PROGRAMMING
Authors: HUANG HONG-ZHONG , TIAN ZHI-GANG , GU YING-KUI
Published: September 2004

In this paper, a new multiobjective optimization approach named interactive physical programming is proposed and used to solve the reliability and redundancy apportionment optimization problem. Interactive physical programming extends physical programming6 to an interactive framework. After the designer specifies which objectives need to be improved and which objectives can be sacrificed, interactive physical programming can obtain the Pareto solutions satisfying such improving preferences. It has good convergence performance, and can obtain satisfactory design in the end. Interactive physical programming has been successfully applied to a reliability and redundancy apportionment optimization problem. It provides a new effective approach for reliability optimization.