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Multiple Signals (multiple + signal)

Distribution by Scientific Domains
Life Sciences50%

Terms modified by Multiple Signals

  • multiple signal transduction pathway
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    Selected Abstracts

    Cell-cycle deregulation in BALB/c 3T3 cells transformed by 1,2-dibromoethane and folpet pesticides

    ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 5 2003
    Maria Alessandra Santucci
    Abstract The cell-transforming potential of 1,2-dibromoethane and folpet, two widely used agricultural pesticides that are potential sources of environmental pollution, has been previously ascribed to their promoting activity. In this study, we investigated whether BALB/c 3T3 transformation by these chemicals was associated with the deregulation of signals involved in cell-cycle progression and in cell-cycle checkpoint induction. We found that two BALB/c 3T3 cell clones transformed by in vitro medium-term (8-week) exposure to the carcinogens had a constitutive acceleration of cell transition from G1 to S phase and an abrogation of the radiation-induced G1/S checkpoint. These events involved multiple signals; in particular, the inhibitors of cyclin/cyclin-dependent kinase complexes p21 and p27 were significantly down-modulated and the positive regulators of cell-cycle progression cyclin D3 and E were up-modulated. As anticipated for cells where the G1/S checkpoint was abrogated, the transformed cells exhibited a significant reinforcement of the radiation-induced G2/M checkpoint, the only checkpoint remaining to protect genomic integrity. However, cyclin A1 and B1 coexpression and cyclin A1 overexpression were found despite the G2 arrest in irradiated cells and these signals likely attenuate the G2/M checkpoint. These alterations to normal cell cycling may promote the emergence of both numerical and structural chromosomal abnormalities and their tolerance. Such a condition could play a key role in neoplastic transformation and be crucial in tumor progression. Furthermore, cyclin A1 overexpression may play an autonomous role in the neoplastic transformation of BALB/c 3T3 cells, as it does in other cell types of mesenchymal origin. Environ. Mol. Mutagen. 41:315,321, 2003. © 2003 Wiley-Liss, Inc. [source]

    Intra- and Intersexual Selection for Multiple Traits in the Peacock (Pavo cristatus)

    ETHOLOGY, Issue 9 2005
    Adeline Loyau
    Animal communication involves a multitude of signals ranging from morphological to behavioural traits. In spite of the diversity of traits used in animal signalling, most studies of sexual selection have focused on single male traits. Moreover, the two forces of sexual selection (male,male competition and female preference) may target different traits and favour the diversification of male signalling. Still, little is known on the combined effects of intra- and intersexual selection on the evolution of multiple signals. The peacock is often cited as one of the best examples of the strength of sexual selection in producing exaggerated traits. Here, we investigated traits under intra- and intersexual selection in a population of free-ranging common peafowl. Peacocks with longer trains and tarsi were more likely to establish a display territory in a central position within the lek and had a higher number of intrusions and agonistic interactions. These traits appeared therefore to be under intrasexual selection. Female selection was assessed as the number of copulations. Mating success was positively correlated with behavioural traits (display activity) and with train ornamentation (number and density of ocelli) suggesting that females use multiple cues during mate selection. Therefore, intra- and intersexual selection seem to operate on different sets of traits. Overall, our results stress the role of multiple receivers on the evolution of multiple signals. [source]

    Survey of sparse and non-sparse methods in source separation

    INTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 1 2005
    Paul D. O'Grady
    Abstract Source separation arises in a variety of signal processing applications, ranging from speech processing to medical image analysis. The separation of a superposition of multiple signals is accomplished by taking into account the structure of the mixing process and by making assumptions about the sources. When the information about the mixing process and sources is limited, the problem is called ,blind'. By assuming that the sources can be represented sparsely in a given basis, recent research has demonstrated that solutions to previously problematic blind source separation problems can be obtained. In some cases, solutions are possible to problems intractable by previous non-sparse methods. Indeed, sparse methods provide a powerful approach to the separation of linear mixtures of independent data. This paper surveys the recent arrival of sparse blind source separation methods and the previously existing non-sparse methods, providing insights and appropriate hooks into theliterature along the way. © 2005 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 15;18,33;2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20035 [source]

    Early warning of agglomeration in fluidized beds by attractor comparison

    AICHE JOURNAL, Issue 11 2000
    J. Ruud van Ommen
    An enhanced monitoring method, based on pressure fluctuation measurements, for observing nonstationarities in fluidized-bed hydrodynamics is presented. Experiments show that it can detect small changes in the particle-size distribution. Such a monitoring method is useful to give an early warning of the onset of agglomeration in a fluidized bed. In contrast to earlier methods, this method is insensitive to small changes in superficial gas velocity and can handle multiple signals, making it relevant to industrial application. By carefully choosing the measurement position, the method becomes also insensitive to small bed mass variations. It uses the attractor reconstructed from a measured pressure signal, which is a "fingerprint" of the hydrodynamics of the fluidized bed for a certain set of conditions. Using this method statistically the reconstructed attractor of a reference time series of pressure fluctuations (representing the desired fluidization behavior) is compared with that of successive time series measured during the bed operation. [source]

    Repression of virulence genes by phosphorylation-dependent oligomerization ofCsrR at target promoters in S. pyogenes

    MOLECULAR MICROBIOLOGY, Issue 4 2001
    Alita A. Miller
    csrRS encodes a two-component regulatory system that represses the transcription of a number of virulence factors in Streptococcus pyogenes, including the hyaluronic acid capsule and pyrogenic exotoxin B. CsrRS-regulated virulence factors have diverse functions during pathogenesis and are differentially expressed throughout growth. This suggests that multiple signals induce CsrRS-mediated gene regulation, or that regulated genes respond differently to CsrR, or both. As a first step in dissecting the csrRS signal transduction pathway, we determined the mechanism by which CsrR mediates the repression of its target promoters. We found that phosphorylated CsrR binds directly to all but one of the promoters of its regulated genes, with different affinities. Phosphorylation of CsrR enhances both oligomerization and DNA binding. We defined the binding site of CsrR at each of the regulated promoters using DNase I and hydroxyl radical footprinting. Based on these results, we propose a model for differential regulation by CsrRS. [source]

    Enhancement of throughput and fairness in 4G wireless access systems by non-orthogonal signaling

    BELL LABS TECHNICAL JOURNAL, Issue 4 2009
    Joerg Schaepperle
    Besides having significantly enhanced throughput, fourth generation (4G) cellular wireless access systems are expected to be cost efficient and provide sufficient performance even at the cell edge. This paper proposes a new method, called radial space-division multiple access (RDMA) for improving the system's spectral efficiency significantly and providing fairness among users without increasing the number of antennas and without requiring fast backbone communication and synchronization between base stations. The basic idea is to approach the capacity of the multi-user channel under fairness constraints by exploiting not only the angular dimension of space, as in space-division multiple access (SDMA), but also the radial dimension. Non-orthogonal signaling for simultaneous transmission of multiple signals over the same radio resource and joint detection in the receiver are used. Significant throughput gains are achieved with low complexity methods requiring only long term channel statistics and no instantaneous channel state information at the transmitter. Detailed link and first simple systemlevel simulation results in the context of the evolution of IEEE 802.16/Worldwide Interoperability for Microwave Access (WiMAX) systems towards 802.16m show that system throughput can be doubled without requiring more advanced analog hardware or increasing bandwidth or transmit power. © 2009 Alcatel-Lucent. [source]