bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of compost amendments and operating temperature on diesel fuel bioremediation
Authors: Hesnawi Rafik M , McCartney Daryl M
Published: February 2006

A laboratory study was conducted to investigate the performance of composting bioremediation of a sand material contaminated with diesel fuel and radio-labeled phenanthrene. The material was amended with either fresh feedstock material or finished compost and then incubated at either thermophilic or mesophilic temperatures for 126 d. In controls that were not amended with compost, no mineralization of 14C phenanthrene was detected, whereas treatments that received compost amendments had significant phenanthrene mineralization, ranging from 25% to 42% of initial concentrations. The lowest extractable diesel range organic residual (1092 mg kg–1 total solids) was observed in the treatment receiving fresh compost amendment and incubated at thermophilic temperatures, whereas the highest residual (8507 mg kg–1 total solids) was observed in the control without any amendment. Whereas all the treatments that received amendment dramatically outperformed the control reactors, significant differences were observed among the treatment performances. This suggests that amendment type and operating temperature were important factors impacting bioremediation performance. Key words: compost amendments, bioremediation, diesel fuel, phenanthrene, temperature.
A statistical evaluation of water quality trends in selected water bodies of Newfoundland and Labrador
Authors: Dawe Paula
Published: February 2006

Using water quality data collected since 1986, as part of the Canada–Newfoundland Water Quality Monitoring Agreement, 36 different water quality variables from 65 different water quality monitoring sites were examined for change over time. Moving averages, the Student's t test statistic, and Spearman's rank correlation coefficient were used. Throughout the province, turbidity and colour were generally displaying deteriorating trends, while conductivity, copper, lead, and mercury were consistently displaying improving trends. There was a notable deteriorating trend in nitrate and nitrite and nitrogen in select river basins, and an improving trend in phosphorous in more developed basins. Even in pristine watersheds, change was often observed in metals, major ions, turbidity, and colour. An examination of land and water use activities ongoing in each watershed allowed identification of likely localized causes and (or) factors contributing to observed water quality trends. In many cases trend-causing factors appeared to be more global in nature and most trends could be explained by an upward trend in river flows during the period analyzed. Key words: water quality, Newfoundland, Labrador, trends, Spearman, land use, statistics, streamflow.
Isolation and characterization of chitinases from Verticillium lecanii
Authors: Lu Zhen-Xiang , Laroche André , Huang Hung Chang
Published: February 2006

Degenerate PCR primers corresponding to conserved domains of fungal chitinases were designed, and PCR was performed on genomic DNA of the entomogenous fungus Verticillium lecanii (Zimmermann) Viegas. Two distinct PCR fragments, chf1 and chf2, were isolated and used to identify two DNA contigs. Analyses of these two contigs revealed that we had obtained the full-length DNA sequence including the promoter, 5′ untranslated region, open reading frame (ORF), and 3′ untranslated regions for two distinct chitinase-like genes. These two genomic DNA sequences exhibited 51% identity at the amino acid (aa) level and were designed as acidic (chi1) and basic (chi2) chitinase-like genes. The isolated cDNA for chi1 gene is 1110 bp with a predicted protein of 370 aa and molecular mass of 40.93 kDa, and its ORF was uninterrupted in its corresponding genomic DNA sequence. The cDNA for the chi2 gene is 1269 bp, a predicted ORF of 423 aa and molecular mass of 45.95 kDa. In contrast, the ORF was interrupted by three introns in its corresponding genomic DNA. The basic chitinase gene (chi2) was successfully expressed in the Pichia pastoris system; optimum enzymatic activity was observed at 22 °C and at pH 7.5. CHI1 and CHI2 were clustered into two different phylogenetic groups according to their sequence alignments with 28 other fungal chitinases. A chitin-binding domain, comprising two sub-domains that exhibit similarities at the aa level to chitin binding domains in bacteria, was identified in 30 fungal chitinase sequences examined.Key words: fungus, chitin, cloning, sequencing, transformation, Pichia sp. expression.
Growth of canola (Brassica napus) in the presence of plant growth-promoting bacteria and either copper or polycyclic aromatic hydrocarbons
Authors: Reed M L.E , Glick Bernard R
Published: February 2006

Growth of canola (Brassica napus) seeds treated with plant growth-promoting bacteria in copper-contaminated and polycyclic aromatic hydrocarbon (PAH)-contaminated soils was monitored. Pseudomonas asplenii AC, isolated from PAH-contaminated soil, was transformed to express a bacterial gene encoding 1-aminocyclopropane-1-carboxylate (ACC) deaminase, and both native and transformed bacteria were tested for growth promotion. Inoculation of seeds, grown in the presence of copper or creosote, with either native or transformed P. asplenii AC significantly increased root and shoot biomass. Native and transformed P. asplenii AC and transformed P. asplenii AC encapsulated in alginate were equally effective at promoting plant growth in copper-contaminated soils. In creosote-contaminated soils the native bacterium was the least effective, and the transformed encapsulated bacterium was the most effective in growth promotion.Key words: plant growth-promoting bacteria, phytoremediation, copper, polycyclic aromatic hydrocarbons, Brassica napus, ethylene, alginate encapsulation.
Induction of humoral immunity in response to immunization with recombinantMycobacterium bovisBCG expressing the S1 subunit ofBordetella pertussistoxin
Authors: Medeiros Marco A , Armôa Geraldo R.G , Dellagostin Odir A , McIntosh Douglas
Published: February 2006

Two recombinant Mycobacterium bovis BCG (rBCG) vaccine strains were developed for the expression of cytoplasmically located S1 subunit of pertussis toxin, with expression driven by the hsp60 promoter of M. bovis (rBCG/pPB10) or the pAN promoter of Mycobacterium paratuberculosis (rBCG/pPB12). Both strains showed stable expression of equivalent levels of recombinant S1 in vitro and induced long-term (up to 8 months) humoral immune responses in BALB/c mice, although these responses differed quantitatively and qualitatively. Specifically, rBCG/pPB12 induced markedly higher levels of IgG1 than did rBCG/pPB10, and mice immunized with the former strain developed specific long-term memory to S1, as indicated by the production of high levels of S1-specific IgG in response to a sublethal challenge with pertussis toxin 15 months after initial immunization. When considered in combination with previous studies, our data encourage further evaluation of rBCG as a potential means of developing a low-cost whooping cough vaccine based on defined antigens.Key words: recombinant BCG, humoral immune response, B. pertussis.
Cell-wall-bound metal ions are not taken up inNeurospora crassa
Authors: Latha J Naveena Lavanya , Rashmi K , Mohan P Maruthi
Published: February 2006

To establish the relevance of the cell wall in metal ion transport, cobalt uptake was examined in Neurospora crassa. Cobalt taken up was largely surface bound (>90%), resulting in a release of calcium and magnesium. Surface-bound cobalt could not enter intracellular locations upon further incubation of mycelia in a metal-free medium. Saturation of the surface with one metal augured subsequent dose-dependent entry of a different metal into intracellular locations. In comparison with the cobalt-resistant mutant, the cobalt-sensitive strain of N. crassa bound less cobalt on the surface but with significant intracellular accumulation. Our results demonstrate the importance of the cell wall in metal transport, toxicity, and resistance in fungi.Key words: metal transport, metal binding, cell wall, biosorption, Neurospora crassa.
Aureobasidium pullulansmorphology: two adapted polysaccharide stains
Authors: Oller Anna R
Published: February 2006

Morphological stages of Aureobasidium pullulans were investigated utilizing different media ingredients and were visualized by bright-field microscopy. A polysaccharide stain was developed to stain chlamydospores, cell walls, hyphae, and conidia, since current staining techniques do not reveal subcellular details to identify fungi, especially those that exhibit polysaccharide secretions.Key words: Aureobasidium, morphology, polysaccharide, pullulan, stain.
Expression of the chloride channel CLC-K in human airway epithelial cells
Authors: Mummery Jennifer L. , Killey Jennifer , Linsdell Paul
Published: February 2006

Airway submucosal gland function is severely disrupted in cystic fibrosis (CF), as a result of genetic mutation of the cystic fibrosis transmembrane conductance regulator (CFTR), an apical membrane Cl– channel. To identify other Cl– channel types that could potentially substitute for lost CFTR function in these cells, we investigated the functional and molecular expression of Cl– channels in Calu-3 cells, a human cell line model of the submucosal gland serous cell. Whole cell patch clamp recording from these cells identified outwardly rectified, pH- and calcium-sensitive Cl– currents that resemble those previously ascribed to ClC-K type chloride channels. Using reverse transcription – polymerase chain reaction, we identified expression of mRNA for ClC-2, ClC-3, ClC-4, ClC-5, ClC-6, ClC-7, ClC-Ka, and ClC-Kb, as well as the common ClC-K channel β subunit barttin. Western blotting confirmed that Calu-3 cells express both ClC-K and barttin protein. Thus, Calu-3 cells express multiple members of the ClC family of Cl– channels that, if also expressed in native submucosal gland serous cells within the CF lung, could perhaps act to partially substitute lost CFTR function. Furthermore, this work represents the first evidence for functional ClC-K chloride channel expression within the lung.
Rofecoxib and tramadol do not attenuate delayed-onset muscle soreness or ischaemic pain in human volunteers
Authors: Loram L.C. , Mitchell D. , Fuller A.
Published: February 2006

We assessed the effect of rofecoxib, a cyclo-oxygenase-2 inhibitor, and tramadol, a centrally acting analgesic, on both delayed-onset muscle soreness (DOMS) and experimentally induced ischaemic pain. We induced DOMS in 10 male and 5 female healthy volunteers by downhill running for 30 min at a 12% decline and a speed of 9 km·h–1. We also induced ischaemic pain by finger movements with an arterial tourniquet around the arm. In a randomized, double-blind crossover format, we administered rofecoxib (50 mg, daily), tramadol (50 mg, 3 times per day), and a placebo (orally for 3 days), starting immediately after exercise. A 100 mm visual analogue scale (VAS) and McGill pain questionnaire were used to describe muscle soreness and ischaemic forearm pain 24 h after the exercise. The pressure pain threshold (PPT) in the thigh and ischaemic pain tolerance in the forearm were measured before exercise and 24 and 72 h after exercise. PPT decreased 24 h after exercise, compared with pre-exercise values (ANOVA, p < 0.05), but neither drug had any significant effect on the PPT. Neither rofecoxib nor tramadol had any effect on time of ischaemia tolerated or amount of finger activity during ischaemia. The VAS and pain-rating index, for both muscle soreness and experimental ischaemic pain, were not affected significantly by either drug. Both DOMS and ischaemic pain share peripheral and central mechanisms, yet neither are attenuated by rofecoxib or tramadol.
Serial magnetic resonance imaging based assessment of the early effects of an ACE inhibitor on postinfarction left ventricular remodeling in rats
Authors: Prunier Fabrice , Marescaux Laurent , Franconi Florence , Thia Alain , Legras Pierre , Lejeune Jean-Jacques , Furber Alain
Published: February 2006

In vivo assessment of treatment efficacy on postinfarct left ventricular (LV) remodeling is crucial for experimental studies. We examined the technical feasibility of serial magnetic resonance imaging (MRI) for monitoring early postinfarct remodeling in rats. MRI studies were performed with a 7-Tesla unit, 1, 3, 8, 15, and 30 days after myocardial infarction (MI) or sham operation, to measure LV mass, volume, and the ejection fraction (EF). Three groups of animals were analyzed: sham-operated rats (n = 6), MI rats receiving lisinopril (n = 11), and MI rats receiving placebo (n = 8). LV dilation occurred on day 3 in both MI groups. LV end-systolic and end-diastolic volumes were significantly lower in lisinopril-treated rats than in placebo-treated rats at days 15 and 30. EF was lower in both MI groups than in the sham group at all time points, and did not differ between the MI groups during follow-up. Less LV hypertrophy was observed in rats receiving lisinopril than in rats receiving placebo at days 15 and 30. We found acceptable within- and between-observer agreement and an excellent correlation between MRI and ex vivo LV mass (r = 0.96; p < 0.001). We demonstrated the ability of MRI to detect the early beneficial impact of angiotensin-converting enzyme (ACE) inhibitors on LV remodeling. Accurate and noninvasive, MRI is the tool of choice to document response to treatment targeting postinfarction LV remodeling in rats.
Molecular defects in cardiac myofibrillar proteins due to thyroid hormone imbalance and diabetesThis paper is a part of a series in the Journal's "Made in Canada" section. The paper has undergone peer review.
Authors: Machackova Jarmila , Barta Judit , Dhalla Naranjan S.
Published: February 2006

The heart very often becomes a victim of endocrine abnormalities such as thyroid hormone imbalance and insulin deficiency, which are manifested in a broad spectrum of cardiac dysfunction from mildly compromised function to severe heart failure. These functional changes in the heart are largely independent of alterations in the coronary arteries and instead reside at the level of cardiomyocytes. The status of cardiac function reflects the net of underlying subcellular modifications induced by an increase or decrease in thyroid hormone and insulin plasma levels. Changes in the contractile and regulatory proteins constitute molecular and structural alterations in myofibrillar assembly, called myofibrillar remodeling. These alterations may be adaptive or maladaptive with respect to the functional and metabolic demands on the heart as a consequence of the altered endocrine status in the body. There is a substantial body of information to indicate alterations in myofibrillar proteins including actin, myosin, tropomyosin, troponin, titin, desmin, and myosin-binding protein C in conditions such as hyperthyroidism, hypothyroidism, and diabetes. The present article is focussed on discussion how myofibrillar proteins are altered in response to thyroid hormone imbalance and lack of insulin or its responsiveness, and how their structural and functional changes explain the contractile defects in the heart.
THE PREDICTION OF MASS OF Z′-BOSON IN A FLAVOR-INDEPENDENT POTENTIAL MODEL
Authors: SAHOO S. , MEIKAP A. K. , MAHARANA L.
Published: February 2006

The mass of Z′ boson is considered in a flavor-independent phenomenological potential model. We have used the low energy parameters and the estimated value so obtained is accessible to experiments at low energies.
POYNTING FLUX DOMINATED ACCRETION FLOW: A TWO-DIMENSIONAL MODEL
Authors: LEE HYUN KYU
Published: February 2006

The dynamics of the accretion flow onto a black hole driven by Poynting flux is discussed in a simplified model of a two-dimensional accretion disk on equatorial plane. In an axisymmetric, stationary and force-free magnetosphere, the accretion flow is described by the three accretion equations obtained from the conservation of stress–energy tensor and one stream equation for a force-free magnetosphere. It is found that the angular velocity of the magnetic surface can be obtained by the dynamics of the accreting matter, [Formula: see text]. The effect of the magnetic field on the accretion flow is discussed in detail using the paraboloidal type configuration suggested by Blandford in 1976. In numerical analysis, it is demonstrated that the angular velocity of the disk, ΩD, deviates from the Keplerian angular velocity and the dynamics of the accretion disk is found to depend strongly on the ratio of the accretion rate to the magnetic field strength.
DIMINISHED UPPER BOUNDS ON THE UNIFICATION MASS SCALES FOR HEAVY HIGGS BOSON MASSES
Authors: ELIAS V. , HOMAYOUNI S. , JEFFREY D. J.
Published: February 2006

We consider dominant three-, four- and five-loop contributions to λ, the quartic scalar coupling-constant's β-function in the Standard Model. We find that these terms accelerate the evolution of λ to nonperturbative values, thereby lowering the unification bound for which scalar-couplings are still perturbative. We also find that these higher order contributions imply a substantial lowering of λ itself before the anticipated onset of nonperturbative physics in the Higgs sector.
KNOTTED SELF-DUAL VORTEX IN GENERALIZED ABELIAN CHERN–SIMONS HIGGS FIELD
Authors: DUAN YI-SHI , ZHONG WOJUN , SI TIEYAN , WANG YONG-QIANG
Published: February 2006

Based on the Bogomol'nyi self-dual equation in the Abelian Chern–Simons Higgs model, we find a self-dual topological term which was ignored all the time in the Bogomol'nyi self-duality equation due to the improper decomposition of the complex Higgs field. We also present a generalized self-dual equation for the first time which unified the topological term and nontopological term in (2+1) space–time. It is shown that the self-dual vortex just arise from the symmetric phase of the Higgs field ϕ = 0, this provides a deep insight into the spontaneous symmetry breaking mechanism. When generalizing this model into (3+1) space–time, we show that the topological number on a family of knotted vortex are just the sum of linking number and self-linking number. We also find this topological charge is conserved during the splitting, the mergence and the intersection processes of knotted vortex lines.
EFFECTIVE EQUATIONS ON THE 3-BRANE WORLD FROM TYPE IIB STRING
Authors: GONŢA DENIS
Published: February 2006

The effective field equations on a 3-brane are established considering the massless bosonic sector of the type IIB string compactified on S5. The covariant embedding formalism in a space endowed with Z2-symmetry is applied. Recently the derivation of the effective equations on the 3-brane, where only gravity penetrates in the bulk was performed by Shiromizu, Maeda, and Sasaki. We extend this approach to the situation when the bulk contains a set of fields given by the type IIB string. The notion of the Einstein–Cartan space is considered in order to avoid extra suppositions about the embedding of these fields. The interactions between the brane and the bulk fields are understood in a purely geometric way, which fixes the form of these interactions. Finally, we present the dynamically equivalent effective equations expressed completely in Riemannian terms and make conclusions.
LOCALITY, CAUSALITY AND NONCOMMUTATIVE GEOMETRY
Authors: CHU CHONG-SUN , FURUTA KO , INAMI TAKEO
Published: February 2006

We analyze the causality condition in noncommutative field theory and show that the nonlocality of noncommutative interaction leads to a modification of the light cone to the light wedge. This effect is generic for noncommutative geometry. We also check that the usual form of energy condition is violated and propose that a new form is needed in noncommutative space–time. On reduction from light cone to light wedge, it looks like the noncommutative dimensions are effectively washed out and suggests a reformulation of noncommutative field theory in terms of lower dimensional degree of freedom. This reduction of dimensions due to noncommutative geometry could play a key role in explaining the holographic property of quantum gravity.
DOES THE ΔI = 1/2 RULE HOLD IN D AND B→ππ DECAYS?
Authors: GUO PENG , HE XIAO-GANG , LI XUE-QIAN
Published: February 2006

Although two pion decays of K, D and B have similar isospin structures, there are dramatic differences in the ratios RK and RD,B of amplitudes from ΔI = 3/2 and ΔI = 1/2 interactions. In K→ππ decays there is the famous ΔI = 1/2 rule with RK ≈ 1/22, whereas in B(D) → ππ decays the ratios RD,B are of order one and therefore there is no such a rule. In this work we study decay amplitudes in B(D)→ππ using QCD factorization calculations paying particular attention to discrepancies between data and theoretical estimates. Since isospin does not play a special role in factorization calculations, no ΔI = 1/2 rule is expected. We find that theoretical results on the size of the amplitudes are in qualitative agreement with data. However the phases for the amplitudes are very different. We show that the effects of rescattering between the two pions in the final state can play a crucial rule in understanding the differences between B(D)→ππ and K→ππ decays. We also comment on the role of isospin analysis which applies to the study of CP violation in B→ππ decays.
LORENTZ-NONINVARIANT NEUTRINO OSCILLATIONS: MODEL AND PREDICTIONS
Authors: KLINKHAMER FRANS R.
Published: February 2006

We present a three-parameter neutrino-oscillation model for three flavors of massless neutrinos with Fermi-point splitting and tri-maximal mixing angles. One of these parameters is the T-violating phase ∊, for which the experimental results from K2K and KamLAND appear to favor a nonzero value. In this paper, we give further model predictions for neutrino oscillations. Upcoming experiments will be able to test this simple model and the general idea of Fermi-point splitting. Possible implications for proposed experiments and neutrino factories are also discussed.
NEAR FORWARD pp ELASTIC SCATTERING AT LHC AND NUCLEON STRUCTURE
Authors: ISLAM M. M. , LUDDY R. J. , PROKUDIN A. V.
Published: February 2006

High energy pp and [Formula: see text] elastic scattering carried out at CERN ISR and SPS Collider and at Fermilab Tevatron are studied first in a model where the nucleon has an outer cloud and an inner core. Elastic scattering is viewed as primarily due to two processes: (a) diffraction scattering originating from cloud–cloud interaction; (b) a hard or large |t| scattering originating from one nucleon core scattering off the other via vector meson ω exchange, while their outer clouds interact independently. For small |t| diffraction dominates, but the hard scattering takes over as |t| increases. The ω-exchange amplitude shows that ω behaves like an elementary vector meson at high energy, contrary to a regge pole behavior. This behavior, however, can be understood in the nonlinear σ-model where ω couples to a topological baryonic current like a gauge boson, and the nucleon is described as a topological soliton. Further investigation shows that the underlying effective field theory model is a gauged Gell-Mann–Levy type linear σ-model that has not only the pion sector and the Wess–Zumino–Witten action of the nonlinear σ-model, but also a quark sector where quarks and antiquarks interact via a scalar field. The scalar field vanishes near the center of the nucleon, but rises sharply at some critical distance to its vacuum value fπ leading to a [Formula: see text] condensate analogous to a BCS condensate in superconductivity. The nucleon structure that emerges then is that the nucleon has an outer cloud of [Formula: see text] condensed ground state, an inner core of topological baryonic charge probed by ω, and a still smaller quark-bag containing massless valence quarks. Large |t|pp elastic scattering is attributed to valence quark–quark elastic scattering, which is taken to be due to the hard pomeron (BFKL pomeron with next to leading order corrections). The parameters in the model are determined by requiring that they satisfactorily describe the known asymptotic behavior of σ tot (s) and ρ(s), and the measured [Formula: see text] at [Formula: see text], 630 GeV, and 1.8 TeV. The model is then used to predict pp elastic differential cross-section at LHC at [Formula: see text] and |t| = 0–10 GeV 2. Our predicted dσ/dt at 14 TeV is found to be very different from those predicted by the impact-picture model and the eikonalized pomeron–reggeon model. Precise measurement of dσ/dt at LHC by the TOTEM group will be able to distinguish between these models. If our predicted dσ/dt is quantitatively confirmed, then it will indicate that various novel ideas developed to describe the nucleon combine and lead to a unique physical description of its structure.
SCATTERING OF ATOMS BY LIGHT: MEASURING THE QUANTUM STATE OF THE FIELD IN A CAVITY
Authors: DE OLIVEIRA GUILHERME C. , DE ALMEIDA AGNALDO R. , SOUZA MARTA J. F. S. , MORAES ARTHUR M. , DANTAS CELIA M. A.
Published: February 2006

This work consists in a generalization of the developed method to measure the quantum state of the field in a cavity with all non null coefficients, in the number representation, through one photon interaction. We present a strategy to measure the quantum state of the field when it has all non-null coefficients or only even or odd coefficients through a two-photons atom-field interaction.
LSDA+U APPROXIMATION-BASED ANALYSIS OF THE ELECTRONIC STRUCTURE OF CeFeGe3
Authors: CHIGO-ANOTA E. , FLORES-RIVEROS A. , RIVAS-SILVA J. F.
Published: February 2006

We perform ab initio electronic structure calculations of the intermetallic compound CeFeGe 3 by means of the Tight Binding Linear Muffin-Tin Orbitals-Atomic Sphere Approximation (TB-LMTO-ASA) within the Local Spin Density Approximation containing the so-called Hubbard correction term ( LSDA+U SIC), using the Stuttgart's TB (Tight Binding)-LMTO-ASA code in the framework of the Density Functional Theory (DFT). At the LSDA-vBH level, our electronic structure calculations indicate an intermediate valence character compound whereas a DOS (density of states) analysis favors its metallic nature. We also study electronic correlation effects via the introduction of the U parameter on Ce and Fe , where a metallic and magnetic characters for this compound are found, along with certain features that may possibly be associated with a heavy fermion system.
THREE-MODE ENTANGLED STATE OF AN ATOMIC BOSE–EINSTEIN CONDENSATE IN A THREE-WELL POTENTIAL
Authors: LIU JIN-MING , WANG YU-ZHU
Published: February 2006

In this paper, we present a scheme to generate a three-mode entangled state of an atomic Bose–Einstein condensate in a symmetric three-well potential by using controlled atomic elastic collisions. Then, by means of the method for calculating the formation entanglement of two qubits, we obtain the analytic expressions of the residual entanglement of the three-mode BEC entangled state.
DEVELOPMENT OF HIGHLY CONDUCTIVE BORON-DOPED MICROCRYSTALLINE SILICON FILMS FOR APPLICATION IN SOLAR CELLS
Authors: LEI QING-SONG , WU ZHI-MENG , XI JIAN-PING , GENG XIN-HUA , ZHAO YING , SUN JIAN
Published: February 2006

We have examined the deposition of highly conductive boron-doped microcrystalline silicon (μc- Si:H ) films for application in solar cells. Depositions were conducted in a very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) chamber. In the deposition processes, various substrate temperatures (TS) were applied. Highly conductive p-type microcrystalline silicon films were obtained at substrate temperature lower than 210°C. The factors that affect the conductivity of the films were investigated. Results suggest that the dark conductivity, which was determined by the Hall mobility and carrier concentration, is influenced by the structure. The properties of the films are strongly dependent on the substrate temperature. With TS increasing, the dark conductivity (σd) increases initially; reach the maximum values at certain TS and then decrease. Also, we applied the boron-doped μc- Si:H as p-layers to the solar cells. An efficiency of about 8.5% for a solar cell with μc- Si:H p-layer was obtained.
BIFURCATIONS OF RELAXATION OSCILLATIONS NEAR FOLDED SADDLES
Authors: GUCKENHEIMER JOHN , HOFFMAN KATHLEEN , WECKESSER WARREN
Published: February 2006

Relaxation oscillations are periodic orbits of multiple time scale dynamical systems that contain both slow and fast segments. The slow–fast decomposition of these orbits is defined in the singular limit. Geometric methods in singular perturbation theory classify degeneracies of these decompositions that occur in generic one-parameter families of relaxation oscillations. This paper investigates the bifurcations that are associated with one type of degeneracy that occurs in systems with two slow variables, in which relaxation oscillations become homoclinic to a folded saddle.
DYNAMICAL ASPECTS OF INTERACTION NETWORKS
Authors: NICOLIS G. , CANTÚ A. GARCÍA , NICOLIS C.
Published: February 2006

A connection between dynamical systems and network theory is outlined based on a mapping of the dynamics into a discrete probabilistic process, whereby the phase space is partitioned into finite size cells. It is found that the connectivity patterns of networks generated by deterministic systems can be related to the indicators of the dynamics such as local Lyapunov exponents. The procedure is extended to networks generated by stochastic processes.
FOOD WEB CHAOS WITHOUT SUBCHAIN OSCILLATORS
Authors: BOCKELMAN BRIAN , DENG BO
Published: February 2006

A basic food web of four species is considered, of which there is a bottom prey X, two competing predators Y, Z on X, and a super predator W only on Y. The main finding is that population chaos does not require the existence of oscillators in any subsystem of the web. This minimum population chaos is demonstrated by increasing the relative reproductive rate of Z alone without alternating any other parameter nor any nullcline of the system. It occurs as the result of a period-doubling cascade from a Hopf bifurcation point. The method of singular perturbation is used to determine the Hopf bifurcation involved as well as the parameter values.
SLOW–FAST DYNAMICS GENERATED BY NONINVERTIBLE PLANE MAPS
Authors: MIRA CHRISTIAN , SHILNIKOV ANDREY
Published: February 2006

The present paper focuses on the two time scale dynamics generated by 2D polynomial noninvertible maps T of (Z0 - Z2) and (Z1 - Z3 - Z1) types. This symbolism, specific to noninvertible maps, means that the phase plane is partitioned into zones Zk, where each point possesses the k real rank-one preimages. Of special interest here is the structure of slow and fast motion sets of such maps. The formation mechanism of a stable invariant close curve through the interaction of fast and slow dynamics, as well as its transformation into a canard are studied. A few among the plethora of chaotic attractors and chaotic transients produced by such maps are described as well.
PRACTICAL COMPUTATION OF NORMAL FORMS ON CENTER MANIFOLDS AT DEGENERATE BOGDANOV–TAKENS BIFURCATIONS
Authors: KUZNETSOV YU. A.
Published: February 2006

Simple computational formulas are derived for the two-, three-, and four-order coefficients of the smooth normal form on the center manifold at the Bogdanov–Takens (nonsemisimple double-zero) bifurcation for n-dimensional systems with arbitrary n ≥ 2. These formulas are equally suitable for both symbolic and numerical evaluation and allow one to classify all codim 3 Bogdanov–Takens bifurcations in generic multidimensional ODEs. They are also applicable to systems with symmetries. We perform no preliminary linear transformations but use only critical (generalized) eigenvectors of the linearization matrix and its transpose. The derivation combines the approximation of the center manifold with the normalization on it. Three known models are used as test examples to demonstrate advantages of the method.
ENTRAINMENT OF MODULATION FREQUENCY: A CASE STUDY
Authors: SCHNEIDER KLAUS R.
Published: February 2006

We consider a system of autonomous ODE's which is S1-equivariant and has a family of asymptotically stable modulated wave solutions with wave frequency α0 and modulation frequency β0. This system will be perturbed, where the applied nonautonomous force also represents a modulated wave, but with wave frequency α and modulations frequency β. The strength of this perturbation is not necessarily small. Our goal is to look for conditions such that the perturbed system exhibits an approximate entrainment of the modulation frequency β on any given finite time interval, where the approximation error can be controlled by the wave frequency.
CHAOS IN SPATIALLY EXTENDED SYSTEMS VIA THE PEAK-CROSSING BIFURCATION
Authors: BERGER ARNO , BUNIMOVICH LEONID A.
Published: February 2006

Individual sites in spatially extended systems of coupled identical maps may exhibit chaotic behavior even if their intrinsic (local) dynamics is regular and stable. For this to happen it is imperative that the spatial interactions are sufficiently strong. So far, this scenario of generating chaos from simple local dynamics has been established rigorously only for special, very narrow classes of local maps. The present article largely extends previous results by showing that the corresponding mechanism of peak-crossing is in fact very general and robust: whenever the local map is sufficiently expanding and exhibits a horseshoe then the emergence of spatial intermittency will be observed in the form of chaotically oscillating sites surrounded by quasi-regular clusters. The results firmly establish peak-crossing as a natural scenario on the route to spacetime chaos.
ON THE ATTRACTORS OF TWO-DIMENSIONAL RAYLEIGH OSCILLATORS INCLUDING NOISE
Authors: ERDMANN UDO , EBELING WERNER
Published: February 2006

We study sustained oscillations in two-dimensional oscillator systems driven by Rayleigh-type negative friction. In particular, we investigate the influence of mismatch of the two frequencies. Further we study the influence of external noise and nonlinearity of the conservative forces. Our consideration is restricted to the case that the driving is rather weak and that the forces show only weak deviations from radial symmetry. For this case we provide results for the attractors and the bifurcations of the system. We show that for rational relations of the frequencies the system develops several rotational excitations with right/left symmetry, corresponding to limit cycles in the four-dimensional phase space. The corresponding noisy distributions have the form of hoops or tires in the four-dimensional space. For irrational frequency relations, as well as for increasing strength of driving or noise the periodic excitations are replaced by chaotic oscillations.
QUALITATIVE THEORY OF DYNAMICAL SYSTEMS, CHAOS AND CONTEMPORARY WIRELESS COMMUNICATIONS
Authors: ANDREYEV YU. V. , DMITRIEV A. S. , EFREMOVA E. V. , KHILINSKY A. D. , KUZMIN L. V.
Published: February 2006

This paper shows how the qualitative theory of dynamical systems, that is intensively developed during the last forty years, is currently applied in practice to provide effective wireless ultrawideband communications using chaotic information carrier.
ON THE STRUCTURE OF 1 : 4 RESONANCES IN HÉNON MAPS
Authors: GONCHENKO M. S.
Published: February 2006

We study bifurcations of fixed points with multipliers e±iπ/2 (the main 1 : 4 resonances) for certain Hénon-like maps, namely for conservative cubic Hénon maps, and conservative and near-conservative generalized Hénon maps. We find conditions of nondegeneracy of the corresponding resonances and give a description of accompanying bifurcations.
LOCAL ACTIVITY IS THE ORIGIN OF COMPLEXITY
Authors: CHUA LEON O.
Published: February 2006

Many scientists have struggled to uncover the elusive origin of "complexity", and its many equivalent jargons, such as emergence, self-organization, synergetics, collective behaviors, nonequilibrium phenomena, etc. They have provided some qualitative, but not quantitative, characterizations of numerous fascinating examples from many disciplines. For example, Schrödinger had identified "the exchange of energy" from open systems as a necessary condition for complexity. Prigogine has argued for the need to introduce a new principle of nature which he dubbed "the instability of the homogeneous". Turing had proposed "symmetry breaking" as an origin of morphogenesis. Smale had asked what "axiomatic" properties must a reaction–diffusion system possess to make the Turing interacting system oscillate.

The purpose of this paper is to show that all the jargons and issues cited above are mere manifestations of a new fundamental principle called local activity, which is mathematically precise and testable. The local activity theorem provides the quantitative characterization of Prigogine's "instability of the homogeneous" and Smale's quest for an axiomatic principle on Turing instability.

Among other things, a mathematical proof is given which shows none of the complexity-related jargons cited above is possible without local activity. Explicit mathematical criteria are given to identify a relatively small subset of the locally-active parameter region, called the edge of chaos, where most complex phenomena emerge.
NAVIGATION AMONG MOVABLE OBSTACLES: REAL-TIME REASONING IN COMPLEX ENVIRONMENTS
Authors: STILMAN MIKE , KUFFNER JAMES J.
Published: February 2006

In this paper, we address the problem of Navigation Among Movable Obstacles (NAMO): a practical extension to navigation for humanoids and other dexterous mobile robots. The robot is permitted to reconfigure the environment by moving obstacles and clearing free space for a path. This paper presents a resolution complete planner for a subclass of NAMO problems. Our planner takes advantage of the navigational structure through state-space decomposition and heuristic search. The planning complexity is reduced to the difficulty of the specific navigation task, rather than the dimensionality of the multi-object domain. We demonstrate real-time results for spaces that contain large numbers of movable obstacles. We also present a practical framework for single-agent search that can be used in algorithmic reasoning about this domain.
A FAST AND EFFICIENT MODEL FOR LEARNING TO REACH
Authors: SUN GANGHUA , SCASSELLATI BRIAN
Published: February 2006

This paper proposes a self-supervised model which enables a humanoid robot to learn to reach to visual targets. Only 400 training samples are used to learn a forward kinematic model of the six degree-of-freedom (DOF) arm. The forward model is represented compactly with just 150 hidden neurons and enables high accuracy reaching in real time. We provide an optimization process for the learning parameters and a careful analysis of reaching errors. An extension of the model is presented to address additional DOFs in the neck. The consistency of the model with physiological and psychological observations is elaborated.
SYNTHESIS OF WHOLE-BODY BEHAVIORS THROUGH HIERARCHICAL CONTROL OF BEHAVIORAL PRIMITIVES
Authors: SENTIS LUIS , KHATIB OUSSAMA
Published: February 2006

To synthesize whole-body behaviors interactively, multiple behavioral primitives need to be simultaneously controlled, including those that guarantee that the constraints imposed by the robot's structure and the external environment are satisfied. Behavioral primitives are entities for the control of various movement criteria, e.g. primitives describing the behavior of the center of gravity, the behaviors of the hands, legs, and head, the body attitude and posture, the constrained body parts such as joint-limits and contacts, etc. By aggregating multiple primitives, we synthesize whole-body behaviors. For safety and for efficient control, we establish a control hierarchy among behavioral primitives, which is exploited to establish control priorities among the different control categories, i.e. constraints, operational tasks, and postures. Constraints should always be guaranteed, while operational tasks should be accomplished without violating the acting constraints, and the posture should control the residual movement redundancy. In this paper, we will present a multi-level hierarchical control structure that allows the establishment of general priorities among behavioral primitives, and we will describe compliant control strategies for efficient control under contact interactions.
A perceptual framework for the auditory display of scientific data
Authors: Barrass Stephen
Published: February 2006

A principal requirement of the auditory display of scientific data is an accurate portrayal of the information contained in the data. The characteristics of the display device can significantly affect the faithfulness of the data presentation. Human hearing is a complex nonlinear process and the intuitive comprehension of the display requires consideration of perceptual interactions and the natural connection between the data and the perception of the data. This chapter proposes a perceptual framework for observable and systematic specification and comprehension of sounds in a device-independent auditory display of scientific data. The framework consists of a perceptually scaled sound space and a display model that maps points from the perceptual space to a display device parameter space while preserving the interrelationships between them. The advantages of a perceptual space are described using the example of an established framework for applying perceptually uniform color models to scientific visualization. A perceptual sound space is defined and constructed by scaling a naturally ordered sound model derived from research studies in timbre perception. An auditory display is implemented on a Sun Sparc10 workstation using Csound and samples of musical instruments. The display model consists of an interpolated mapping from perceptual space to display space and a description of the display gamut that is the boundary in perceptual space between points that the display can realize and those that it cannot. The display gamut can be used to analyze the display, compare displays, and optimize data mapping sequences for the display. The concepts are illustrated by a graphic visualization of the gamut of the implemented display as a geometric shape in the perceptual sound space.
A comprehensive framework for auditory display
Authors: Barrass Stephen
Published: February 2006

In ‘A Perceptual Framework for the Auditory Display of Scientific Data’ I described the first perceptually scaled sound space designed specifically for sonification. I modeled this sound space, and its underlying theory, on the use of perceptual colour spaces in scientific visualization. As I went on to apply the sound space in mappings of satellite data I introduced methods of data characterization and user-centered task analysis into my design framework. In trials I realized that satellite images allow you to see global information across millions of data values, whereas it was impossible to play all the data at once as sounds. This lead me to explore perceptual streaming as a means for perceiving similarity and difference in masses of sounded data. In work on sonifications for virtual reality applications I recognized the need to consider the semiotic linkage of the sound with the application domain, and the need to also link the sound with the interaction metaphor.The work described in this paper laid the foundation for the ongoing development of a comprehensive framework for auditory display that takes into consideration the perceptual organization of the sounds, the characteristics of the data, the gamut of the display device, the user's tasks, the semiotic linkage to the application domain, and the affordances for interaction.
Sonification design and metaphors
Authors: Walker Bruce N. , Kramer Gregory
Published: February 2006

The original Walker and Kramer paper at ICAD 1996 studied the mapping of data dimensions (e.g., temperature) onto sound dimensions (e.g., pitch). In this commentary we consider the historical and methodological context of that early work, discuss its relevance to the field of auditory display, and point out how it forms part of a body of work with ties to other researchers in the ICAD community.
A principled methodology for the specification and design of nonvisual widgets
Authors: Edwards Alistair D. N. , Mitsopoulos Evangelos
Published: February 2006

When the visual channel of communication is unavailable because the user is blind, nonvisual user interfaces must be developed. The proposed methodology consists of three interrelated specification levels. Information and supported tasks are specified in abstract terms at the conceptual level, taking into account requirements imposed by manipulation of interaction devices and information provided by analysis of the visual representation. The perceptual structure of the auditory scene is specified next at the structural level and then the physical dimensions of sound are defined at the implementation level. The methodology is applied to the specification of a simple listbox widget.
Perceptual auditory design
Authors: Edwards Alistair D. N. , Mitsopoulos Evangelos
Published: February 2006

Mitsopoulos and Edwards ICAD 1998 paper deals with the design of auditory widgets as exemplars of applying sound psychological theories of auditory perception and attention in the field of auditory interface design. The research, briefly herein described, is presented in detail in Mitsopoulos [2000]. Future work at all three levels of the methodology is foreseen, as well as in the integration of input and output modalities.
The design and evaluation of a sonically enhanced tool palette
Authors: Brewster Stephen A. , Clarke Catherine V.
Published: February 2006

This paper describes an experiment to investigate the effectiveness of adding sound to tool palettes. Palettes have usability problems because users need to see the information they present, but they are often outside the area of visual focus. We used nonspeech sounds called earcons to indicate the current tool and when tool changes occurred so that users could tell what tool they were in wherever they were looking. Results showed a significant reduction in the number of tasks performed with the wrong tool. Therefore, users knew what the current tool was and did not try to perform tasks with the wrong one. All of this was not at the expense of making the tool palettes any more annoying to use.
Desktop data sonification
Authors: Flowers John H. , Turnage Kimberly D. , Buhman Dion C.
Published: February 2006

Sonification tools have not yet become typical components of data analysis software, despite dramatic advances in sound-production capabilities of personal computers over the past decade. However, we continue to believe that auditory displays have the potential to be highly useful for “small scale” exploration of data for normally sighted users as well as an alternative format for users with visual impairment. Demonstration of effective examples of auditory data displays and design of
flexible
software tools for data sonification will be key factors in determining the impact of this method of data representation.