Self-phase modulation dependent dispersion mitigation in high power SSB and DSB + dispersion compensated modulated radio-over-fiber links

The joint effect of fiber chromatic dispersion and fiber nonlinearity onto single-sideband and double-sideband modulated radio-over-fiber links is investigated. Experimental and simulated results show that modulation suppression caused by the chromatic dispersion in radio-over-fiber links can be successfully eliminated in both schemes only when the system is in the linear regime. Under nonlinear transmission the received microwave carrier power depends on the optical incident power.

Experimental comparison of fibre and grating-based dispersion compensation schemes for 40 channel 10Gb/s DWDM systems

We report an experimental comparison between broadband fibre Bragg gratings (FBGs) and conventional dispersion compensating fibre (DCF) for a 40 x 10Gb/s DWDM system over 525km. A performanceoptimised configuration using FBG compensators is presented.

Physics and mathematics of dispersion-managed optical solitons

We review the main physical and mathematical properties of dispersion-managed (DM) optical solitons. Theory of DM solitons can be presented at two levels of accuracy: first, simple, but nevertheless, quantitative models based on ordinary differential equations governing evolution of the soliton width and phase parameter (the so-called chirp); and second, a comprehensive path-average theory that is capable of describing in detail both the fine structure of DM soliton form and its evolution along the fiber line. An analogy between DM soliton and a macroscopic nonlinear quantum oscillator model is also discussed. © 2003 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS. All rights reserved.

Optimization of gain and SNR in bi-directionally pumped dispersion compensating amplifier modules

In this paper, we present an analysis and optimisation of the performance of bi-directionally pumped dispersion compensation modules acting as simultaneous Raman amplifiers, with optimal configurations for operation with different fibers commercially available. The ratio between forward and backward pump powers for minimum noise influence is obtained in each case, with improvements in the SNR of up to 8 dB when compared to a purely backward-pumped case.

5,745 km DWDM transcontinental field trial using 10 Gbit/s dispersion managed solitons and dynamic gain equalization

Error free unregenerated transmission is demonstrated looped-back over 5,745 km (62 spans) of installed SSMF along the Adelaide-Perth leg of the IP1 Australia network, which is now the world's longest commercially deployed unregenerated 10 Gbit/s DWDM terrestrial transmission system. © 2000 Optical Society of America.

Chromatic dispersion effect in a microwave photonic filter using superstructured fiber Bragg grating and dispersive fiber

In this paper a microwave photonic filter using superstructured fiber Bragg grating and dispersive fiber is investigated. A theoretical model to describe the transfer function of the filter taking into consideration the spectral width of light source is established. Experiments are carried out to verify the theoretical analysis. Both theoretical and experimental results indicate that due to chromatic dispersion the source spectral width introduces an additional power penalty to the microwave photonic response of the filter. © 2005 Optical Society of America.

Channel estimation and compensation in chromatic dispersion limited optical fast OFDM systems

We experimentally investigate the channel estimation and compensation in a chromatic dispersion (CD) limited 20Gbit/s optical fast orthogonal frequency division multiplexing (F-OFDM) system with up to 840km transmission. It is shown that symmetric extension based guard interval (GI) is required to enable CD compensation using one-tap equalizers. As few as one optical F-OFDM symbol with four and six pilot tones per symbol can achieve near-optimal channel estimation and compensation performance for 600km and 840km respectively.

Genomic evaluation during permeability of indomethacin and its solid dispersion

Drug resistance was first identified in cancer cells that express proteins known as multidrug resistance proteins that extrude the therapeutic agents out of the cells resulting in alteration of pharmacokinetics, tissue distribution, and pharmacodynamics of drugs. To this end studies were carried out to investigate the role of pharmacological inhibitors and pharmaceutical excipients with a primary focus on P-glycoprotein (P-gp). The aim of this study was to investigate holistic changes in transporter gene expression during permeability upon formulation of indomethacin as solid dispersion. Initial characterization studies of solid dispersion of indomethacin showed that the drug was dispersed within the carrier in amorphous form. Analysis of permeability data across Caco-2 monolayers revealed that drug absorption increased by 4-fold when reformulated as solid dispersion. The last phase of the work involved investigation of gene expression changes of transporter genes during permeability. The results showed that there were significant differences in the expression of both ATP-binding cassette (ABC) transporter genes as well as solute carrier transporter (SLC) genes suggesting that the inclusion of polyethylene glycol as well as changes in molecular form of drug from crystalline to amorphous have a significant bearing on the expression of transporter network genes resulting in differences in drug permeability. © 2011 Informa UK, Ltd.

Localized waves in optical systems with periodic dispersion and nonlinearity management

We overview our recent developments in the theory of dispersion-managed (DM) solitons within the context of optical applications. First, we present a class of localized solutions with a period multiple to that of the standard DM soliton in the nonlinear Schrödinger equation with periodic variations of the dispersion. In the framework of a reduced ordinary differential equation-based model, we discuss the key features of these structures, such as a smaller energy compared to traditional DM solitons with the same temporal width. Next, we present new results on dissipative DM solitons, which occur in the context of mode-locked lasers. By means of numerical simulations and a reduced variational model of the complex Ginzburg-Landau equation, we analyze the influence of the different dissipative processes that take place in a laser.

Proposal and design of airy-based rocket pulses for invariant propagation in lossy dispersive media

A novel kind of Airy-based pulse with an invariant propagation in lossy dispersive media is proposed. The basic principle is based on an optical energy trade-off between different parts of the pulse caused by the chromatic dispersion, which is used to compensate the attenuation losses of the propagation medium. Although the ideal concept of the proposed pulses implies infinite pulse energy, the numerical simulations show that practical finite energy pulses can be designed to obtain a partially invariant propagation over a finite distance of propagation.

Management of slow light dispersion and delay time characteristics with SNAP bottle resonators

The nanoscale radius variation of a bottle microresonator with the required dispersion characteristics is determined theoretically. Experimentally, a microresonator with the footprint 0.08 mm2 exhibiting 20 ns/nm dispersion compensation of 100 ps pulses is demonstrated. © 2014 OSA.

Dispersion Phenomena in Dunkl-Schrödinger Equation and Applications

2000 Mathematics Subject Classification: 35Q55,42B10.

Anti-quorum sensing agents from south Florida medicinal plants and their attenuation of Pseudomonas aeruginosa pathogenicity

With the difficulty in treating recalcitrant infections and the growing resistance to antibiotics, new therapeutic modalities are becoming increasingly necessary. The interruption of bacterial quorum sensing (QS), or cell-cell communication is known to attenuate virulence, while limiting selective pressure toward resistance. This study initiates an ethnobotanically-directed search for QS inhibiting agents in south Florida medicinal plants. Fifty plants were screened for anti-QS activity using two biomonitor strains, Chromobacterium violaceum and Agrobacterium tumefaciens. Of these plants, six showed QS inhibition: Conocarpus erectus L. (Combretaceae), Chamaecyce hypericifolia (L.) Millsp. (Euphorbiaceae), Callistemon viminalis (Sol.ex Gaertn.) G. Don (Myrtaceae), Bucida burceras L. (Combretaceae), Tetrazygia bicolor (Mill.) Cogn. (Melastomataceae), and Quercus virginiana Mill. (Fagaceae). These plants were further examined for their effects on the QS system and virulence of Pseudomonas aeruginosa, an intractable opportunistic pathogen responsible for morbidity and mortality in the immunocompromised patient. C. erectus, B. buceras, and C. viminalis were found to significantly inhibit multiple virulence factors and biofilm formation in this organism. Each plant presented a distinct profile of effect on QS genes and signaling molecules, suggesting varying modes of action. Virulence attenuation was observed with marginal reduction of bacterial growth, suggesting quorum quenching mechanisms unrelated to static or cidal effects. Extracts of these plants were also investigated for their effects on P. aeruginosa killing of the nematode Caenorhabditis elegans. Results were evaluated in both toxin-based and infection-based assays with P. aeruginosa strains PA01 and PA14. Overall nematode mortality was reduced 50-90%. There was no indication of host toxicity, suggesting the potential for further development as anti-infectives. Using low-pressure chromatography and HPLC, two stereoisomeric ellagitannins, vescalagin and castalagin were isolated from an aqueous extract of C. erectus . Structures were confirmed via mass spectrometry and NMR spectroscopy. Both ellagitannins were shown to decrease signal production, QS gene expression, and virulence factor production in P. aeruginosa. This study introduces a potentially new therapeutic direction for the treatment of bacterial infections. In addition, this is the first report of vescalagin and castalagin being isolated from C. erectus, and the first report of ellagitannin activity on the QS system.

Anti-Quorum Sensing Agents from South Florida Medicinal Plants and their Attenuation of Pseudomonas Aeruginosa Pathogenicity

With the difficulty in treating recalcitrant infections and the growing resistance to antibiotics, new therapeutic modalities are becoming increasingly necessary. The interruption of bacterial quorum sensing (QS), or cell-cell communication is known to attenuate virulence, while limiting selective pressure toward resistance. This study initiates an ethnobotanically-directed search for QS inhibiting agents in south Florida medicinal plants. Fifty plants were screened for anti-QS activity using two biomonitor strains, Chromobacterium violaceum and Agrobacterium tumefaciens. Of these plants, six showed QS inhibition: Conocarpus erectus L. (Combretaceae), Chamaecyce hypericifolia (L.) Millsp. (Euphorbiaceae), Callistemon viminalis (Sol.ex Gaertn.) G. Don (Myrtaceae), Bucida burceras L. (Combretaceae), Tetrazygia bicolor (Mill.) Cogn. (Melastomataceae), and Quercus virginiana Mill. (Fagaceae). These plants were further examined for their effects on the QS system and virulence of Pseudomonas aeruginosa, an intractable opportunistic pathogen responsible for morbidity and mortality in the immunocompromised patient. C. erectus, B. buceras, and C. viminalis were found to significantly inhibit multiple virulence factors and biofilm formation in this organism. Each plant presented a distinct profile of effect on QS genes and signaling molecules, suggesting varying modes of action. Virulence attenuation was observed with marginal reduction of bacterial growth, suggesting quorum quenching mechanisms unrelated to static or cidal effects. Extracts of these plants were also investigated for their effects on P. aeruginosa killing of the nematode Caenorhabditis elegans. Results were evaluated in both toxin-based and infection-based assays with P. aeruginosa strains PA01 and PA14. Overall nematode mortality was reduced 50-90%. There was no indication of host toxicity, suggesting the potential for further development as anti-infectives. Using low-pressure chromatography and HPLC, two stereoisomeric ellagitannins, vescalagin and castalagin were isolated from an aqueous extract of C. erectus. Structures were confirmed via mass spectrometry and NMR spectroscopy. Both ellagitannins were shown to decrease signal production, QS gene expression, and virulence factor production in P. aeruginosa. This study introduces a potentially new therapeutic direction for the treatment of bacterial infections. In addition, this is the first report of vescalagin and castalagin being isolated from C. erectus, and the first report of ellagitannin activity on the QS system.

Dispersion and energy relations in periodic chains and grids

In this study wave propagation, dispersion relations, and energy relations for linear elastic periodic systems are analyzed. In particular, the dispersion relations for monoatomic chain of infinite dimension are obtained analytically by writing the Block-type wave equation for a unit cell in order to capture the dynamic behavior for chains under prescribed vibration. By comparing the discretized model (mass-spring chain) with the solid bar system, the nonlinearity of the dispersion relation for chain indicates that the periodic lattice is dispersive in contrast to the continuous rod, which is non dispersive. Further investigations have been performed considering one-dimensional diatomic linear elastic mass-spring chain. The dispersion relations, energy velocity, and group velocity have been derived. At certain range of frequencies harmonic plane waves do not propagate in contrast with monoatomic chain. Also, since the diatomic chain considered is a linear elastic chain, both of the energy velocity and the group velocity are identical. As long as the linear elastic condition is considered the results show zero flux condition without residual energy. In addition, this paper shows that the diatomic chain dispersion relations are independent on the unit cell scheme. Finally, an extension for the study covers the dispersion and energy relations for 2D- grid system. The 2x2 grid system show a periodicity of the dispersion surface in the wavenumber domain. In addition, the symmetry of the surface can be exploited to identify an Irreducible Brillouin Zone (IBZ). Compact representations of the dispersion properties of multidimensional periodic systems are obtained by plotting frequency as the wave vector’s components vary along the boundary of the IBZ, which leads to a widely accepted and effective visualization of bandgaps and overall dispersion properties.