Search results for "biological applications"

showing 6 items of 6 documents

Modified post-bifurcation dynamics and routes to chaos from double-Hopf bifurcations in a hyperchaotic system

2012

In order to understand the onset of hyperchaotic behavior recently observed in many systems, we study bifurcations in the modified Chen system leading from simple dynamics into chaotic regimes. In particular, we demonstrate that the existence of only one fixed point of the system in all regions of parameter space implies that this simple point attractor may only be destabilized via a Hopf or double Hopf bifurcation as system parameters are varied. Saddle-node, transcritical and pitchfork bifurcations are precluded. The normal form immediately following double Hopf bifurcations is constructed analytically by the method of multiple scales. Analysis of this generalized double Hopf normal form …

Hopf bifurcationApplied MathematicsMechanical EngineeringMathematical analysisAerospace EngineeringOcean EngineeringContext (language use)Parameter spaceBiological applications of bifurcation theoryNonlinear Sciences::Chaotic Dynamicssymbols.namesakePitchfork bifurcationControl and Systems EngineeringControl theoryQuasiperiodic functionAttractorsymbolsElectrical and Electronic EngineeringDouble-Hopf bifurcations – Normal forms – Modified post-bifurcation dynamicsSettore MAT/07 - Fisica MatematicaNonlinear Sciences::Pattern Formation and SolitonsBifurcationMathematicsNonlinear Dynamics
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LbL multilayer capsules: recent progress and future outlook for their use in life sciences.

2010

In this review we provide an overview of the recent progress in designing composite polymer capsules based on the Layer-by-Layer (LbL) technology demonstrated so far in material science, focusing on their potential applications in medicine, drug delivery and catalysis. The benefits and limits of current systems are discussed and the perspectives on emerging strategies for designing novel classes of therapeutic vehicles are highlighted. © 2010 The Royal Society of Chemistry.

Materials scienceDrug Delivery SystemsPharmaceutical PreparationsPolymersComposite polymerDrug deliveryGeneral Materials ScienceNanotechnologyCapsuleslayer-by-layer; polymer capsules; biological applicationsBiological Science DisciplinesCatalysisNanoscale
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Programmable Supercontinuum Laser Spectrum Generator Based on a Liquid-Crystal on Silicon Spatial Light Modulator

2021

Supercontinuum (SC) lasers combine a broadband light spectrum with the unique properties of single-mode lasers. In this work we present an optical system to spectrally filter a SC laser source using liquid-crystal on silicon (LCoS) spatial light modulators (SLM). The proposed optical system disperses the input laser and the spectrally separated components are projected onto the LCoS-SLM, where the state of polarization of each wavelength is separately modulated. Finally, recombining the modulated spectral components results in an output laser source where the spectrum can be controlled dynamically from a computer. The system incorporates two branches to independently control the visible (VI…

Materials scienceMaterials Science (miscellaneous)BiophysicsPhysics::OpticsGeneral Physics and Astronomybroadband light sources02 engineering and technology01 natural sciencesSpectral linelaw.invention010309 opticsbiological applicationslaw0103 physical sciencesliquid crystal on siliconPhysical and Theoretical ChemistryMathematical PhysicsSpatial light modulatorbusiness.industryNear-infrared spectroscopy021001 nanoscience & nanotechnologyLaserPolarization (waves)lcsh:QC1-999SupercontinuumLiquid crystal on siliconWavelengthsupercontinuum lasermicroscopyOptoelectronicsspatial light modulators0210 nano-technologybusinesslcsh:PhysicsFrontiers in Physics
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Pattern formation driven by cross–diffusion in a 2D domain

2012

Abstract In this work we investigate the process of pattern formation in a two dimensional domain for a reaction–diffusion system with nonlinear diffusion terms and the competitive Lotka–Volterra kinetics. The linear stability analysis shows that cross-diffusion, through Turing bifurcation, is the key mechanism for the formation of spatial patterns. We show that the bifurcation can be regular, degenerate non-resonant and resonant. We use multiple scales expansions to derive the amplitude equations appropriate for each case and show that the system supports patterns like rolls, squares, mixed-mode patterns, supersquares, and hexagonal patterns.

Pattern formationFOS: Physical sciencesSaddle-node bifurcationPattern Formation and Solitons (nlin.PS)Dynamical Systems (math.DS)Bifurcation diagramDomain (mathematical analysis)Reaction–diffusion systemFOS: MathematicsMathematics - Dynamical SystemsBifurcationMathematical PhysicsMathematicsApplied MathematicsNonlinear diffusionTuring instabilityDegenerate energy levelsMathematical analysisGeneral EngineeringGeneral MedicineMathematical Physics (math-ph)Nonlinear Sciences - Pattern Formation and SolitonsBiological applications of bifurcation theoryComputational MathematicsAmplitude equationGeneral Economics Econometrics and FinanceSubcritical bifurcationAnalysis
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Remarks on the economic interpretation of Hopf bifurcations

1999

Abstract The Hopf bifurcation theorem has become a frequently used tool in the study of nonlinear dynamical economic systems. In this paper, it is shown that phenomena like multiple limit cycles, hysteresis loops and catastrophic transitions may possibly accompany a Hopf bifurcation. The theoretical argument is illustrated in Foley's liquidity cost–business cycle model.

Period-doubling bifurcationHopf bifurcationEconomics and EconometricsPure mathematicsSaddle-node bifurcationBifurcation diagramBiological applications of bifurcation theoryNonlinear systemsymbols.namesakeHysteresis (economics)symbolsInfinite-period bifurcationMathematical economicsFinanceMathematicsEconomics Letters
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Rapid and eco-friendly synthesis of graphene oxide-silica nanohybrids

2014

The increasing interest in Graphene oxide (GO) is due to many issues: the presence of both sp2-conjugated atoms and oxygen-containing functional groups provides a strong hydrophilicity and the possibility to further functionalize it with other molecules (i.e. π-π interactions covalent attachment etc.) [1]. Furthermore since the GO is biocompatible and noncytotoxic many studies have been recently focused on the development of GO-based nanodevices for bioimaging DNA detection drug delivery. Due to their low cytotoxicity and large internal surface area silica nanoparticles have been taken into account as promising material for biolabeling and drug loading/delivery. Particular consideration has recently been demonstrated for GO-silica composites because of the potentialities for electrical applications their chemical inertia and stability toward ions exposure. The possibility to combine the extraordinary properties of GO and silica offers several advantages for the realization of nanoprobes for biological applications and of biosensor [12]. The strategy for the fabrication of GO-nanosilica nanohybrids can be schematized as follows: (i) synthesis of GO by oxidizing graphite powder with the method described by Marcano et al. [3] (ii) Preparation of oxygen-loaded silica nanoparticles by thermal treatments in controlled atmosphere in order to induce high NIR emission at 1272 nm from high purity silica nanoparticles. (iii) preparation of GrO-silica nanohybrid films via rapid solvent casting in water. The nanohybrids were tested by XPS FTIR Raman analysis UV photoluminescence analysis TGA Zeta potential measurements electrical tests AFM and SEM. Several nanohybrids were prepared by combining two different typologies of GO and two different samples of silica.
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