Types Of Crosstalk Research Articles

Crosstalk attenuation for imaging of multiples based on angle gather residual moveout analysis

Imaging of multiples, as a supplement to imaging of primaries, can provide a wider range of subsurface illumination. Therefore, it can provide more detailed information on subsurface structures. However, imaging of multiples suffers from crosstalk issues generated by unrelated events. Many strategies have been proposed to attenuate crosstalk, among which the angle domain Radon crosstalk attenuation algorithm achieves good application effect. In the angle domain, the true imaging is flat, while the crosstalk events have moveouts. Therefore, it is convenient to identify the crosstalk in angle gathers using the Radon transform. However, the conventional Radon transform lacks a quantitative description for crosstalk in angle gathers, which would affect the accuracy of crosstalk attenuation. In this paper, residual moveout kernels are derived with a Radon transform to attenuate crosstalk in angle gathers for imaging of multiples. First, two types of residual moveout (RMO) equations are derived based on the causality of crosstalk. A three-layer model is used to verify the correctness of the analytical solutions. Then, based on the derived equations, the two types of crosstalk can be attenuated respectively in the Radon domain. Synthetic experiments demonstrate that the derived RMO equations can effectively attenuate the crosstalk events in imaging of multiples.

Analysis and removal of crosstalk in a time-multiplexed light-field display.

Time-multiplexed light-field displays (TMLFDs) can provide natural and realistic three-dimensional (3D) performance with a wide 120° viewing angle, which provides broad potential applications in 3D electronic sand table (EST) technology. However, current TMLFDs suffer from severe crosstalk, which can lead to image aliasing and the distortion of the depth information. In this paper, the mechanisms underlying the emergence of crosstalk in TMLFD systems are identified and analyzed. The results indicate that the specific structure of the slanted lenticular lens array (LLA) and the non-uniformity of the emergent light distribution in the lens elements are the two main factors responsible for the crosstalk. In order to produce clear depth perception and improve the image quality, a novel ladder-type LCD sub-pixel arrangement and a compound lens with three aspheric surfaces are proposed and introduced into a TMLFD to respectively reduce the two types of crosstalk. Crosstalk simulation experiments demonstrate the validity of the proposed methods. Structural similarity (SSIM) simulation experiments and light-field reconstruction experiments also indicate that aliasing is effectively reduced and the depth quality is significantly improved over the entire viewing range. In addition, a tabletop 3D EST based on the proposed TMLFD is presented. The proposed approaches to crosstalk reduction are also compatible with other lenticular lens-based 3D displays.

Twitching and Swimming Motility Play a Role in Ralstonia solanacearum Pathogenicity.

Ralstonia solanacearum is a bacterial plant pathogen causing important economic losses worldwide. In addition to the polar flagella responsible for swimming motility, this pathogen produces type IV pili (TFP) that govern twitching motility, a flagellum-independent movement on solid surfaces. The implication of chemotaxis in plant colonization, through the control flagellar rotation by the proteins CheW and CheA, has been previously reported in R. solanacearum In this work, we have identified in this bacterium homologues of the Pseudomonas aeruginosapilI and chpA genes, suggested to play roles in TFP-associated motility analogous to those played by the cheW and cheA genes, respectively. We demonstrate that R. solanacearum strains with a deletion of the pilI or the chpA coding region show normal swimming and chemotaxis but altered biofilm formation and reduced twitching motility, transformation efficiency, and root attachment. Furthermore, these mutants displayed wild-type growth in planta and impaired virulence on tomato plants after soil-drench inoculations but not when directly applied to the xylem. Comparison with deletion mutants for pilA and fliC-encoding the major pilin and flagellin subunits, respectively-showed that both twitching and swimming are required for plant colonization and full virulence. This work proves for the first time the functionality of a pilus-mediated pathway encoded by pil-chp genes in R. solanacearum, demonstrating that pilI and chpA genes are bona fide motility regulators controlling twitching motility and its three related phenotypes: virulence, natural transformation, and biofilm formation.IMPORTANCE Twitching and swimming are two bacterial movements governed by pili and flagella. The present work identifies for the first time in the Gram-negative plant pathogen Ralstonia solanacearum a pilus-mediated chemotaxis pathway analogous to that governing flagellum-mediated chemotaxis. We show that regulatory genes in this pathway control all of the phenotypes related to pili, including twitching motility, natural transformation, and biofilm formation, and are also directly implicated in virulence, mainly during the first steps of the plant infection. Our results show that pili have a higher impact than flagella on the interaction of R. solanacearum with tomato plants and reveal new types of cross-talk between the swimming and twitching motility phenotypes: enhanced swimming in bacteria lacking pili and a role for the flagellum in root attachment.

Studies of MCP-PMTs in the miniTimeCube neutrino detector

This report highlights two different types of cross-talk in the photodetectors of the miniTimeCube neutrino experiment. The miniTimeCube detector has 24 8 × 8-anode Photonis MCP-PMT Planacon XP85012, totalling 1536 individual pixels viewing the 2-liter cube of plastic scintillator.

Regulation of Strigolactone Biosynthesis by Gibberellin Signaling.

Strigolactones (SLs) are a class of plant hormones that regulate diverse physiological processes, including shoot branching and root development. They also act as rhizosphere signaling molecules to stimulate the germination of root parasitic weeds and the branching of arbuscular mycorrhizal fungi. Although various types of cross talk between SLs and other hormones have been reported in physiological analyses, the cross talk between gibberellin (GA) and SLs is poorly understood. We screened for chemicals that regulate the level of SLs in rice (Oryza sativa) and identified GA as, to our knowledge, a novel SL-regulating molecule. The regulation of SL biosynthesis by GA is dependent on the GA receptor GID1 and F-box protein GID2. GA treatment also reduced the infection of rice plants by the parasitic plant witchers weed (Striga hermonthica). These data not only demonstrate, to our knowledge, the novel plant hormone cross talk between SL and GA, but also suggest that GA can be used to control parasitic weed infections.

Conducted electromagnetic interference: theoretical and experimental investigation

This paper presents theoretical and experimental study of the mechanisms of conducted couplings, generated by an electromagnetic interference such as the galvanic, capacitive and inductive crosstalk. These couplings are due to various parameters, such as the width and the length of the tracks (or drivers) for the galvanic coupling and the circulation of noise currents and voltages (between the aggressor and the victim) which are caused by the proximity of the tracks and the very high frequency interference signals for the capacitive and inductive coupling. Also, this study shows the increases of the noise level caused by the incrementing of the signal frequency for all different types of crosstalk. This work is validated with empirical formula (for the inductive effect), also by the conventional formulas such as Kirchhoff’s laws (the node law, the mesh law) and by an experimental study (represented by a work bench) on the coupling behavior.

Orthogonal intercellular signaling for programmed spatial behavior.

Bidirectional intercellular signaling is an essential feature of multicellular organisms, and the engineering of complex biological systems will require multiple pathways for intercellular signaling with minimal crosstalk. Natural quorum‐sensing systems provide components for cell communication, but their use is often constrained by signal crosstalk. We have established new orthogonal systems for cell–cell communication using acyl homoserine lactone signaling systems. Quantitative measurements in contexts of differing receiver protein expression allowed us to separate different types of crosstalk between 3‐oxo‐C6‐ and 3‐oxo‐C12‐homoserine lactones, cognate receiver proteins, and DNA promoters. Mutating promoter sequences minimized interactions with heterologous receiver proteins. We used experimental data to parameterize a computational model for signal crosstalk and to estimate the effect of receiver protein levels on signal crosstalk. We used this model to predict optimal expression levels for receiver proteins, to create an effective two‐channel cell communication device. Establishment of a novel spatial assay allowed measurement of interactions between geometrically constrained cell populations via these diffusible signals. We built relay devices capable of long‐range signal propagation mediated by cycles of signal induction, communication and response by discrete cell populations. This work demonstrates the ability to systematically reduce crosstalk within intercellular signaling systems and to use these systems to engineer complex spatiotemporal patterning in cell populations.

Subtype-specific mechanisms for functional interaction between α6β4* nicotinic acetylcholine receptors and P2X receptors.

P2X receptors and nicotinic acetylcholine receptors (nAChRs) display functional and physical interactions in many cell types and heterologous expression systems, but interactions between α6β4-containing (α6β4*) nAChRs and P2X2 receptors and/or P2X3 receptors have not been fully characterized. We measured several types of crosstalk in oocytes coexpressing α6β4 nAChRs and P2X2, P2X3, or P2X2/3 receptors. A novel form of crosstalk occurs between α6β4 nAChRs and P2X2 receptors. P2X2 receptors were forced into a prolonged desensitized state upon activation by ATP through a mechanism that does not depend on the intracellular C terminus of the P2X2 receptors. Coexpression of α6β4 nAChRs with P2X3 receptors shifts the ATP dose-response relation to the right, even in the absence of acetylcholine (ACh). Moreover, currents become nonadditive when ACh and ATP are coapplied, as previously reported for other Cys-loop receptors interacting with P2X receptors, and this crosstalk is dependent on the presence of the P2X3 C-terminal domain. P2X2 receptors also functionally interact with α6β4β3 but through a different mechanism from α6β4. The interaction with P2X3 receptors is less pronounced for the α6β4β3 nAChR than the α6β4 nAChR. We also measured a functional interaction between the α6β4 nAChRs and the heteromeric P2X2/3 receptor. Experiments with the nAChR channel blocker mecamylamine on P2X2-α6β4 oocytes point to the loss of P2X2 channel activity during the crosstalk, whereas the ion channel pores of the P2X receptors were fully functional and unaltered by the receptor interaction for P2X2-α6β4β3, P2X2/3-α6β4, and P2X2/3-α6β4β3. These results may be relevant to dorsal root ganglion cells and to other neurons that coexpress these receptor subunits.

Dynamic Bandplanning for Vectored DSL

There are two types of crosstalk in digital subscriber line (DSL) systems, namely near-end crosstalk (NEXT) and far-end crosstalk (FEXT). NEXT is usually much stronger than FEXT. Therefore, high-speed DSL systems transmit in preplanned disjoint downstream (DS) and upstream (US) frequency bands to avoid NEXT. Although easy for implementation, such a fixed bandplan can lead to inefficient bandwidth usage, depending on the DS and US bit rate requirements and the loop topology, particularly in so-called vectored DSL systems, which include signal coordination for FEXT cancellation. In dynamic bandplanning (DBP), each frequency band is allocated to either DS, US, or to both directions depending on the aforementioned parameters. In this paper, we consider optimal DBP for vectored DSL with linear as well as with nonlinear transmitter/receiver structures. We propose an optimal DBP algorithm for systems with disjoint DS and US bands. For systems with overlapping bands, the problem of finding the optimal transmitter/receiver filters is nonconvex and we propose two iterative algorithms based on recent optimum spectrum balancing schemes from the literature. We also study the effect of echo and US NEXT cancellation on the system performance. Finally, simulation results are provided to demonstrate that our algorithms can indeed significantly increase the achievable bit rates.

Wrist electrogoniometry: are current mathematical correction procedures effective in reducing crosstalk in functional assessment?

The recording of human movement is an essential requirement for biomechanical, clinical, and occupational analysis, allowing assessment of postural variation, occupational risks, and preventive programs in physical therapy and rehabilitation. The flexible electrogoniometer (EGM), considered a reliable and accurate device, is used for dynamic recordings of different joints. Despite these advantages, the EGM is susceptible to measurement errors, known as crosstalk. There are two known types of crosstalk: crosstalk due to sensor rotation and inherent crosstalk. Correction procedures have been proposed to correct these errors; however no study has used both procedures in clinical measures for wrist movements with the aim to optimize the correction. To evaluate the effects of mathematical correction procedures on: 1) crosstalk due to forearm rotation, 2) inherent sensor crosstalk; and 3) the combination of these two procedures. 43 healthy subjects had their maximum range of motion of wrist flexion/extension and ulnar/radials deviation recorded by EGM. The results were analyzed descriptively, and procedures were compared by differences. There was no significant difference in measurements before and after the application of correction procedures (P<0.05). Furthermore, the differences between the correction procedures were less than 5° in most cases, having little impact on the measurements. Considering the time-consuming data analysis, the specific technical knowledge involved, and the inefficient results, the correction procedures are not recommended for wrist recordings by EGM.

Modular modelling of signalling pathways and their cross-talk

Signalling pathways are well-known abstractions that explain the mechanisms whereby cells respond to signals. Collections of pathways form networks, and interactions between pathways in a network, known as cross-talk, enables further complex signalling behaviours. While there are several formal modelling approaches for signalling pathways, none make cross-talk explicit; the aim of this paper is to define and categorise cross-talk in a rigorous way. We define a modular approach to pathway and network modelling, based on the module construct in the PRISM modelling language, and a set of generic signalling modules. Five different types of cross-talk are defined according to various biologically meaningful combinations of variable sharing, synchronisation labels and reaction renaming. The approach is illustrated with a case-study analysis of cross-talk between the TGF-β, WNT and MAPK pathways.

Methods of determining the structure and parameters of interference in remote measurements

Methods of estimating the structure and parameters of interference for the purpose of performing operations involved in scaling of the parameters of interference in measurement and probe channels with compensation of interference caused by different types of crosstalk in the information channels of a telemetry system are proposed. The methods are based on an analysis of the energy spectrum and cospectrum of the information and probe signals.

Crosstalk of thyroid hormone receptor and liver X receptor in lipid metabolism and beyond [Review

Thyroid hormone receptors (TRs) and liver X receptors (LXRs) are members of the nuclear receptor superfamily. Although LXRs and TRs belong to two distinct receptor subgroups with respect to ligand-binding affinity, the two receptor systems show similarity with respect to molecular mechanism, target genes, and physiological roles. Since both TRs and LXRs play an important role in metabolic regulation, form heterodimers with retinoid X receptors (RXRs), and bind to direct repeat-4 (DR-4) with identical geometry and polarity, crosstalk between these two receptors has been reported, especially on lipid metabolism-related genes. Recently, several types of crosstalk between TRs and LXRs have been identified and crosstalk has also been observed in other physiological systems such as central nervous system rather than lipid metabolism. In this review, recent advances in elucidating the molecular mechanisms of the crosstalk between these two nuclear receptors are discussed, with the aim of finding a perspective on unknown roles of TRs and LXRs.

Modelling and Analysis of Biochemical Signalling Pathway Cross-talk

Signalling pathways are abstractions that help life scientists structure the coordination of cellular activity. Cross-talk between pathways accounts for many of the complex behaviours exhibited by signalling pathways and is often critical in producing the correct signal-response relationship. Formal models of signalling pathways and cross-talk in particular can aid understanding and drive experimentation. We define an approach to modelling based on the concept that a pathway is the (synchronising) parallel composition of instances of generic modules (with internal and external labels). Pathways are then composed by (synchronising) parallel composition and renaming; different types of cross-talk result from different combinations of synchronisation and renaming. We define a number of generic modules in PRISM and five types of cross-talk: signal flow, substrate availability, receptor function, gene expression and intracellular communication. We show that Continuous Stochastic Logic properties can both detect and distinguish the types of cross-talk. The approach is illustrated with small examples and an analysis of the cross-talk between the TGF-b/BMP, WNT and MAPK pathways.

The Essential Role of p53 in Hyperpigmentation of the Skin via Regulation of Paracrine Melanogenic Cytokine Receptor Signaling

Hyperpigmentation of the skin is characterized by increases in melanin synthesis and deposition. Although considered a significant psychosocial distress, little is known about the detailed mechanisms of hyperpigmentation. Recently, the tumor suppressor protein p53 has been demonstrated to promote ultraviolet B-induced skin pigmentation by stimulating the transcription of a melanogenic cytokine, POMC (pro-opiomelanocortin), in keratinocytes. Given that p53 can be activated by various kinds of diverse stresses, including sun exposure, inflammation, and aging, this finding led us to examine the involvement of p53 in cytokine receptor signaling, which might result in skin hyperpigmentation. Immunohistochemical and reverse transcription-PCR analyses revealed the increased expression and phosphorylation of p53 in the epidermis of hyperpigmented spots, accompanied by the higher expression of melanogenic cytokines, including stem cell factor, endothelin-1, and POMC. The involvement of p53 in hyperpigmentation was also indicated by the significantly higher expression of p53 transcriptional targets in the epidermis of hyperpigmented spots. Treatment of human keratinocytes and melanocytes with known p53 activators or inhibitors, including pifithrin-alpha (PFT), demonstrated significant increases or decreases, respectively, in the expression of melanogenic factors, including cytokines and their receptors. Additionally, PFT administration abolished stem cell factor-induced phosphorylation of mitogen-activated protein kinase in human melanocytes. Furthermore, when organ-cultured hyperpigmented spots, in vitro human skin substitutes, and mouse skin were treated with PFT or p53 small interfering RNA, the expression of melanogenic cytokines and their receptors was significantly decreased, as were levels of tyrosinase and melanogenesis. Taken together, these data reveal the essential role of p53 in hyperpigmentation of the skin via the regulation of paracrine-cytokine signaling, both in keratinocytes and in melanocytes.

Group X secretory phospholipase A 2 can induce arachidonic acid release and eicosanoid production without activation of cytosolic phospholipase A 2 alpha

Group X secretory phospholipase A 2 (sPLA 2-X) and cytosolic phospholipase A 2 alpha (cPLA 2α) are involved in the release of arachidonic acid (AA) from membrane phospholipids linked to the eicosanoid production in various pathological states. Recent studies have indicated the presence of various types of cross-talk between sPLA 2s and cPLA 2α resulting in effective AA release. Here we examined the dependence of sPLA 2-X-induced potent AA release on the cPLA 2α activation by using specific cPLA 2α or sPLA 2 inhibitors as well as cPLA 2α-deficient mice. We found that Pyrrophenone, a cPLA 2α-specific inhibitor, did not suppress the sPLA 2-X-induced potent AA release and prostaglandin E 2 formation in mouse spleen cells. Furthermore, the amount of AA released by sPLA 2-X from spleen cells was not significantly altered by cPLA 2α deficiency. These results suggest that sPLA 2-X induces potent AA release without activation of cPLA 2α, which might be relevant to eicosanoid production in some pathological states where cPLA 2α is not activated.

New way to describe diffraction from optical disks

An efficient decomposition of the diffraction pattern from optical disks that yields insight into the origin and the characteristics of various signals is described. The Babinet principle is used to separate components that describe the data signal, servo signals, and three types of cross talk. The construction of a basis set that yields efficient calculation for optimization studies is described. Two media types are considered as examples. Several applications are also described, including an explanation for the origin of the differential phase-detection tracking signal that is used with DVD-ROM media.

Impedance Correction of Wave Filters

The present importance of wave filter impedance correction arises chiefly from its relation to crosstalk in carrier systems. Briefly, it appears that line transpositions, an effective remedy for many types of crosstalk, are less satisfactory when directed against the so-called “reflected near-end crosstalk” and “reflected far-end crosstalk” produced when waves reflected from the junctions between lines and repeater equipment of carrier systems induce currents in neighboring systems. The expense of the elaborate transposition scheme necessary for a substantial reduction in these types of crosstalk makes it desirable to diminish the amplitude of the reflected wave as far as possible by the improvement of the impedance match between lines and repeaters. A detailed study shows that this is most conveniently done by terminating the filters in the repeater by sections whose image impedances at one end match the main body of the filter, while at the other they approximate constant resistances, matching the terminal impedances. The development of appropriate filter terminating sections has passed through a number of stages. The earliest filters gave reflection coefficients as great as 50% to 60% in the useful transmission band. The invention of “m-derived” and “x-terminated” filters, plus a number of more or less empirical schemes, made it possible to obtain reflection coefficients ranging from 10% to 15% in the useful band. Recent progress has resulted chiefly from the development of a series of sections, the simplest of which is equivalent to the m-derived type, while the others, of progressively increasing complexity, give progressively better approximations to the ideal characteristic. The use of the more complicated sections has made it possible to reduce filter reflection coefficients to the order of 2%, or even less. At present the chief limitation appears to be the difficulty of manufacturing filters with sufficient precision to allow the theoretical characteristics to be realized. The paper is illustrated by figures showing the various stages of this progress as they are exemplified in actual designs.