Copies Of Signal Research Articles

Network of echoes

The decision making model (DMM) previously developed [3,35] has been shown to generate phase transitions, to be topologically complex as manifest by inverse power-law (IPL) degree distributions, and to produce temporal complexity through IPL distributions in the switching times between the two critical states of consensus. These properties are entailed by the fundamental assumption that the network elements in the DMM imperfectly imitate one another, which is postulated herein as the echo response hypothesis; an echo being an imperfect copy of an original signal. Some implications of this hypothesis for the human sciences are explored.

Packaging signals in single-stranded RNA viruses: nature’s alternative to a purely electrostatic assembly mechanism

The formation of a protective protein container is an essential step in the life-cycle of most viruses. In the case of single-stranded (ss)RNA viruses, this step occurs in parallel with genome packaging in a co-assembly process. Previously, it had been thought that this process can be explained entirely by electrostatics. Inspired by recent single-molecule fluorescence experiments that recapitulate the RNA packaging specificity seen in vivo for two model viruses, we present an alternative theory, which recognizes the important cooperative roles played by RNA–coat protein interactions, at sites we have termed packaging signals. The hypothesis is that multiple copies of packaging signals, repeated according to capsid symmetry, aid formation of the required capsid protein conformers at defined positions, resulting in significantly enhanced assembly efficiency. The precise mechanistic roles of packaging signal interactions may vary between viruses, as we have demonstrated for MS2 and STNV. We quantify the impact of packaging signals on capsid assembly efficiency using a dodecahedral model system, showing that heterogeneous affinity distributions of packaging signals for capsid protein out-compete those of homogeneous affinities. These insights pave the way to a new anti-viral therapy, reducing capsid assembly efficiency by targeting of the vital roles of the packaging signals, and opens up new avenues for the efficient construction of protein nanocontainers in bionanotechnology.

Comparison of Wireless MIMO System Under Alamouti's Scheme and Maximum Ratio Combining Technique

In wireless communication fading of channels is the serious cause of the received degraded signals. The effect of fading can be minimized by using various time and space domain techniques. However, space domain techniques are preferred over the others due to its advantages. In this paper, comparison of the wireless MIMO system under Almouti's and maximum ratio combining schemes is presented. Basic idea in these schemes is to transmit and receive more than one copy of the original signals. Using two transmitter antennas and one receiver antenna, the scheme provides the nearly same diversity order as the maximal-ratio receiver combining (MRRC) with one transmitter antenna, and two receiver antennas. Results for one transmitter and four receivers under MRRC is also presented and compared. Finally, results are presented while varying the average transmitted power.

Increased gene copy number and amplification of FGF2 and FGFR1 in metastatic colorectal cancer.

402 Background: Fibroblast growth factors (FGFs) and their receptors (FGFRs) play essential roles in tightly regulating cell proliferation, survival, migration, and angiogenesis in cancers. However, gene copy number and amplification of FGF2 and FGFR1 have not been extensively evaluated in patients with metastatic colorectal cancer (CRC). Methods: Two tissue microarrays (TMA) were constructed with resected CRC liver metastases from 120 patients. The TMAs included duplicated intratumoral regions and the invasive margin between tumor and normal hepatic parenchyma. Patients were either untreated, or previously treated with FOLFIRI or FOLFOX +/- bevacizumab. The TMA slides were subjected to a two-color FISH assay using a mixture of FGF2 and FGFR1 in-house developed probes. Results: Results were obtained from 118 patients. The analysis detected an average of 1.90 copies of FGF2 signal per cell (range, 1.10-3.46 copies) and an average of 2.27 copies of FGFR1 signal per cell (range, 1-12-7.14 copies). Three control specimens from each slide were also scored, with an average of 1.74 copies of FGF2 and 1.73 copies of FGFR1. High copy number per cell (mean > 2.5 copies) was detected in 9.3% of specimens for FGF2 and 27.9% for FGFR1, including 2 patients (1.7%) for FGF2 and 5 (4.2%) for FGFR1 with focal amplification, defined by ≥ 10% cells with > 4 copies. Additionally, duplications of gene signals in the same locus were detected in 10 samples (8.5%) for FGF2 and 19 (16.1%) for FGFR1. Intratumoral heterogeneity was rare (detected in 3 patients). There was no statistically significant correlation between FGF2 or FGFR1 gene copy number and prior treatment, pathologic response, relapse free survival, or overall survival, though there was a trend towards higher FGFR1 gene copy number in patients previously receiving bevacizumab (p=0.07). Conclusions: Both FGF2 and FGFR1 display variable copy number among resected CRC liver metastases, with larger variability detected for FGFR1. Gene amplification was rare but detected in several patients for both FGF2 and FGFR1. Follow up studies will investigate higher FGFR1 gene copy number in patients previously treated with bevacizumab, perhaps reflecting a potential escape or resistance mechanism.

Colorimetric In Situ Hybridization Identifies MYC Gene Signal Clusters Correlating With Increased Copy Number, mRNA, and Protein in Diffuse Large B-Cell Lymphoma

Abnormalities of the MYC oncogene on chromosome 8 are characteristic of Burkitt lymphoma and other aggressive B-cell lymphomas, including diffuse large B-cell lymphoma (DLBCL). We recently described a colorimetric in situ hybridization (CISH) method for detecting extra copies of the MYC gene in DLBCL and the frequent occurrence of excess copies of discrete MYC signals in the context of diploidy or polyploidy of chromosome 8, which correlated with increased mRNA signals. We further observed enlarged MYC signals, which were counted as a single gene copy but, by their dimension and unusual shape, likely consisted of "clusters" of MYC genes. In this study, we sought to further characterize these clusters of MYC signals by determining whether the presence of these correlated with other genetic features, mRNA levels, protein, and overall survival. We found that MYC clusters correlated with an abnormal MYC locus and with increased mRNA. MYC mRNA correlated with protein levels, and both increased mRNA and protein correlated with poorer overall survival. MYC clusters were seen in both the germinal center and activated B-cell subtypes of DLBCL. Clusters of MYC signals may be an underappreciated, but clinically important, feature of aggressive B-cell lymphomas with potential prognostic and therapeutic relevance.

Noise performance of phase-insensitive multicasting in multi-stage parametric mixers

Noise properties of large-count spectral multicasting in a phase-insensitive parametric mixer were investigated. Scalable multicasting was achieved using two-tone continuous-wave seeded mixers capable of generating more than 20 frequency non-degenerate copies. The mixer was constructed using a multistage architecture to simultaneously manage high Figure-of-Merit frequency generation and suppress noise generation. The performance was characterized by measuring the conversion efficiency and noise figure of all signal copies. Minimum noise figure of 8.09dB was measured. Experimental findings confirm that noise of the multicasted signal does not grow linearly with copy count and that it can be suppressed below this limit.

Coherent optical three-dimensional spectrum-correlation processing of wave signals based on space–time integration

The architectures of classical analog coherent optical (ACO) spectrum analyzers and correlators are not designed to process the wave signal as a whole, i.e., simultaneously in three dimensions. In this paper, the theory of ACO three-dimensional direct spectrum-correlation processing of spatial-temporal optical replicas (copies) of wave signals is discussed. In the single-stage and two-stage ACO systems, the spatial power spectrum and spatial correlation function of the wave signal (envelope) are obtained on the basis of space-time integration. The geometry of the final compressed signal in the output plane of either optical system allows one to evaluate the angle of wave arrival. The wave signal to be processed can theoretically have any form (due to autocorrelation properties of the systems) and an unlimited duration (due to time integration of wave energy and possibility of electronic subtraction of the intermediate bias terms of the time integration).

Audio Watermarking Using Spatial Masking and Ambisonics

Based on the spatial masking phenomenon and Ambisonics, a watermarking technique for audio signals is proposed. Ambisonics is a well known technique to encode and reproduce spatial information related to sound. The proposed method exploits this feature of Ambisonics. A watermark is represented as a slightly rotated version of the original sound scene. In another scenario in which Ambisonic signals are synthesized from mono or stereo signals, watermarks are embedded near the signal by adding a small copy of the host signal. This scenario presents the important advantage that reversible watermarking is possible if loudspeakers are arranged properly for playback. This advantage is attributed to the fact that first order Ambisonics represents audio signals as mutually orthogonal four-channel signals, thereby presenting a larger amount of data than in the original version. Formulation of the proposed method is explained. Listening tests demonstrate the relations between primary parameter values and imperceptibility of the watermark. Computer simulations conducted to assess the robustness of the proposed method against common signal processing attacks demonstrate that the method is robust against most of the tested attacks.

Seismic Monitoring of the North Korea Nuclear Test Site Using a Multichannel Correlation Detector

North Korea announced a second nuclear test on 25 May 2009, the first having taken place on October 9, 2006. Both tests were detected by the global seismic network of the Comprehensive nuclear Test-Ban-Treaty Organisation. We apply a correlation detector using a 10-s signal template from the 2006 test on the MJAR array in Japan to: 1) assess the potential for automatically detecting subsequent explosions at or near the test site; and 2) monitor the associated false alarm rate. The 2009 signal is detected clearly with no false alarms in a three-year period. By detecting scaled-down copies of the explosion signals submerged into background noise, we argue that a significantly smaller explosion at the site would have been detected automatically, with a low false alarm rate. The performance of the correlator on MJAR is not diminished by the signal incoherence that makes conventional array processing problematic at this array. We demonstrate that false alarm elimination by f-k analysis of single channel detection statistic traces is crucial for maintaining a low detection threshold. Correlation detectors are to be advocated as a routine complement to the existing pipeline detectors, both for reducing the detection threshold for sites of interest and providing automatic classification of signals from repeating sources.

Cooperative relaying in OFDMA networks based on the joint use of hierarchical modulation and link adaptation

In cooperative relaying, the base station broadcasts a signal to the destination, the relay overhears it and forwards it in a next time slot to the destination. The latter combines the two received copies of the signal in order to reconstruct the original one. In this study, we consider a relay-based OFDMA network, as is the case of long term evolution advanced systems. We, first, make use of hierarchical modulation to send additional information to the relay so as to enable it to reconstruct a more robust copy of the original signal, and, second, adapt the transmission from the relay to the destination by taking advantage of the typically good radio conditions between them so as to reduce the cost of additional resources needed by relaying and hence improve the overall system capacity. We model such a system at the user level, considering a realistic arrival and departure setting and quantify the gains thus achieved in a cross-layer manner, in terms of throughput and blocking probability. We, eventually, propose an enhancement to the afore-mentioned scheme that takes advantage of the good radio conditions of users who are close to the base station to send them an additional stream using hierarchical modulation.

Does the corollary discharge of attention exist?

We discuss experimental support for the existence of a corollary discharge signal of attention movement control and its formulation in terms of the corollary discharge of attention model of attention movement (CODAM). The data is from fMRI, MEG and EEG activity observed about 200 ms after stimulus onset in various attention paradigms and in which the activity is mainly sited in parietal and extra-striate visual areas. Moreover the data arises from neural activity observed before report of a subject's experience occurs. The overall experimental support for the existence of a copy of the attention movement control signal generates, it is suggested, a viable route to explore the relation between this signal and human consciousness, as concluded in the paper.

Childhood B-cell progenitor acute lymphoblastic leukemia presenting a three-way t(11;12;21)(q14;p13;q22) with a RUNX1 gene signal on chromosome 11

The ETV6/RUNX1 (TEL/AML1) gene fusion is the most common gene rearrangement in childhood B-cell progenitor acute lymphoblastic leukemia (BCP-ALL) that occurs in 19–27% of cases [1]. This gene fusion is caused by the t(12;21)(p13;q22) mutation, which results in a chimeric protein that acts as a trans-dominant repressor of RUNX1regulated target genes [2]. This translocation usually escapes banding cytogenetics, and molecular techniques such as reverse transcriptase polymerase chain reaction (RT-PCR) or fluorescence in situ hybridization (FISH) are useful for its detection [3]. Several studies have shown that ETV6/RUNX1 confers a favorable prognosis in childhood ALL [1]. However, other investigators have shown incidence of the ETV6/RUNX1 in relapsed ALL [4–6]. In addition, most cases of childhood BCP-ALL with the ETV6/RUNX1 fusion relapse late. Features of ETV6/RUNX1 associated with poor prognosis include two copies of the fusion signal, loss of second ETV6 signal and loss of the second RUNX1 or extra signal, near-tetraploid modal number, or a complex karyotype [7]. As cases of BCP-ALL often show poor chromosome morphology, assessing the molecular heterogeneity of ALL cases with the ETV6/RUNX1 fusion requires highly sensitive methods, such as FISHbanding [8]. In the present report, we describe banding and molecular cytogenetic analyses of a childhood BCP-ALL case with t(12;21) harboring a novel three-way molecular variant involving chromosome 11. The patient is a 13-year-old girl admitted to the Hematology Service in Clementino Fraga Filho University Hospital (HUCCF), Rio de Janeiro. On admission, she presented a history of two months of joint pain in the legs, spine (thoracolumbar), right knee, and left shoulder. These symptoms progressed, with fever, epistaxis, and petechial rash in shoulder and legs. Physical examination showed remarkable hepatomegaly (the liver was 10 cm below the right costal margin) and splenomegaly (the spleen was 6 cm below the left costal margin). White blood cell (WBC) count was 26.7 9 10/L, and platelet count was 18 9 10/L. Morphologic evaluation of bone marrow contents showed hypercellularity with 80% blast cells and lymphoid characteristics. Flow cytometry analysis revealed blasts that expressed CD19, CD10, CD20, cIgM, CD79a, and HLADR. Immunohistochemistry analysis revealed 80% of Ki-67 expression. The final diagnosis was BCP-ALL. RT-PCR analysis revealed the ETV6/RUNX1 fusion. The patient was treated according to the hyper-CVAD protocol [9], which resulted in complete remission achieved on day 15 of the treatment. The patient has remained in remission for more than 10 months. Cytogenetic G-banding studies at the time of D. R. Ney-Garcia M. T. de Souza R. R. C. de Matos M. L. M. Silva (&) Cytogenetics Department, Bone Marrow Unit (CEMO), The National Cancer Institute (INCA), Praca da Cruz Vermelha, 23 – 68 floor, Rio de Janeiro, RJ 20.230-130, Brazil e-mail: luizamacedo@inca.gov.br

Molecular Cloning and Functional Characterization of Xenopus tropicalis Frog Transient Receptor Potential Vanilloid 1 Reveal Its Functional Evolution for Heat, Acid, and Capsaicin Sensitivities in Terrestrial Vertebrates

The functional difference of thermosensitive transient receptor potential (TRP) channels in the evolutionary context has attracted attention, but thus far little information is available on the TRP vanilloid 1 (TRPV1) function of amphibians, which diverged earliest from terrestrial vertebrate lineages. In this study we cloned Xenopus tropicalis frog TRPV1 (xtTRPV1), and functional characterization was performed using HeLa cells heterologously expressing xtTRPV1 (xtTRPV1-HeLa) and dorsal root ganglion neurons isolated from X. tropicalis (xtDRG neurons) by measuring changes in the intracellular calcium concentration ([Ca(2+)](i)). The channel activity was also observed in xtTRPV1-expressing Xenopus oocytes. Furthermore, we tested capsaicin- and heat-induced nocifensive behaviors of the frog X. tropicalis in vivo. At the amino acid level, xtTRPV1 displays ∼60% sequence identity to other terrestrial vertebrate TRPV1 orthologues. Capsaicin induced [Ca(2+)](i) increases in xtTRPV1-HeLa and xtDRG neurons and evoked nocifensive behavior in X. tropicalis. However, its sensitivity was extremely low compared with mammalian orthologues. Low extracellular pH and heat activated xtTRPV1-HeLa and xtDRG neurons. Heat also evoked nocifensive behavior. In oocytes expressing xtTRPV1, inward currents were elicited by heat and low extracellular pH. Mutagenesis analysis revealed that two amino acids (tyrosine 523 and alanine 561) were responsible for the low sensitivity to capsaicin. Taken together, our results indicate that xtTRPV1 functions as a polymodal receptor similar to its mammalian orthologues. The present study demonstrates that TRPV1 functions as a heat- and acid-sensitive channel in the ancestor of terrestrial vertebrates. Because it is possible to examine vanilloid and heat sensitivities in vitro and in vivo, X. tropicalis could be the ideal experimental lower vertebrate animal for the study of TRPV1 function.

AMIC: An Expandable Front-End for Gamma-Ray Detectors With Light Distribution Analysis Capabilities

A novel CMOS integrated front-end architecture is presented throughout this paper. It is designed to be used with detectors based on continuous scintillation crystals plus position sensitive photomultiplier. Its structure aims at carrying out an analog computation which extracts fundamental information of the detected event. This fact allows us to avoid an individual acquisition of every input channel so that a large increase of inputs is feasible. In order to accomplish the processing task, a current buffer delivers a copy of each input signal to several computation blocks. Those processing units implement current mode analog filtering operations with a digitally programmable 8-bit precision coefficient for each front-end input. Output currents are summed and sent to the output stage where a buffered current output is provided. A voltage signal is also available by means of a rail-to-rail transresistance amplifier. The final goal is to obtain several moments of the light distribution on the detector surface. Each one provides useful information, such as energy, position, depth of interaction (from the light distribution width), skewness (deformation due to border effect), etc. Since the computation is purely additive, the current outputs can be used as inputs to other equal devices thus creating a fully expandable architecture.

Role of MSTd Extraretinal Signals in Smooth Pursuit Adaptation

The smooth pursuit (SP) system is able to adapt to challenges associated with development or system drift to maintain pursuit accuracy. Short-term adaptation of SP can be produced experimentally using a step-ramp tracking paradigm with 2 steps of velocity (double-step paradigm). Previous studies have demonstrated that the macaque cerebellum plays an essential role in SP adaptation. However, it remains uncertain whether neuronal activity in afferent structures to the cerebellum shows changes associated with SP adaptation. Therefore, we focused on the dorsal-medial part of medial superior temporal cortex (MSTd), which is part of the cortico-ponto-cerebellar pathway thought to provide extraretinal signals needed for maintaining SP. We found that 54% of the SP-related neurons showed significant changes in the first 100 ms of response correlated with adaptive changes of initial pursuit. Our results indicate that some cortical neurons in MSTd could be inside the circuit involved in SP adaptation. Furthermore, our sample of MSTd neurons started their discharge on average 103 ms after SP onset. Therefore, we suggest that extraretinal signals carried in MSTd might be due to efference copy of pursuit eye velocity signals, which reflect plastic changes in the downstream motor output pathways (e.g., the cerebellum).

Parametric Photonic Channelized RF Receiver

A new class of photonic channelized radio-frequency (RF) receiver is proposed and demonstrated. The new device relies on generation of high fidelity signal copies by wavelength multicasting in a self-seeded, two-pump parametric mixer. Signal copying to widely spaced wavelengths enables channelization of the full RF bandwidth using a single periodic filter. The channelization uses freely tunable frequencies of newly generated copies and eliminates the need for construction of a dense, narrowband filter bank. The new concept is demonstrated by channelization of four subcarrier channels with 1-GHz spacing and greater than 20-dB extinction ratio between extracted channels.

Effect of environment on the propagation of electromagnetic waves in GRC 408E digital radiorelay devices

Effect of environment on the propagation of electromagnetic waves in GRC 408E digital radiorelay devices

Advances in Modern Blind Signal Separation Algorithms: Theory and Applications

With human-computer interactions and hands-free communications becoming overwhelmingly important in the new millennium, recent research efforts have been increasingly focusing on state-of-the-art multi-microphone signal processing solutions to improve speech intelligibility in adverse environments. One such prominent statistical signal processing technique is blind signal separation (BSS). BSS was first introduced in the early 1990s and quickly emerged as an area of intense research activity showing huge potential in numerous applications. BSS comprises the task of 'blindly' recovering a set of unknown signals, the so-called sources from their observed mixtures, based on very little to almost no prior knowledge about the source characteristics or the mixing structure. The goal of BSS is to process multi-sensory observations of an inaccessible set of signals in a manner that reveals their individual (and original) form, by exploiting the spatial and temporal diversity, readily accessible through a multi-microphone configuration. Proceeding blindly exhibits a number of advantages, since assumptions about the room configuration and the source-to-sensor geometry can be relaxed without affecting overall efficiency. This booklet investigates one of the most commercially attractive applications of BSS, which is the simultaneous recovery of signals inside a reverberant (naturally echoing) environment, using two (or more) microphones. In this paradigm, each microphone captures not only the direct contributions from each source, but also several reflected copies of the original signals at different propagation delays. These recordings are referred to as the convolutive mixtures of the original sources. The goal of this booklet in the lecture series is to provide insight on recent advances in algorithms, which are ideally suited for blind signal separation of convolutive speech mixtures. More importantly, specific emphasis is given in practical applications of the developed BSS algorithms associated with real-life scenarios. The developed algorithms are put in the context of modern DSP devices, such as hearing aids and cochlear implants, where design requirements dictate low power consumption and call for portability and compact size. Along these lines, this booklet focuses on modern BSS algorithms which address (1) the limited amount of processing power and (2) the small number of microphones available to the end-user. Table of Contents: Fundamentals of blind signal separation / Modern blind signal separation algorithms / Application of blind signal processing strategies to noise reduction for the hearing-impaired / Conclusions and future challenges / Bibliography

Area, speed and power measurements of FPGA-based complex orthogonal space-time block code channel encoders

Space-time coding (STC) is an important milestone in modern wireless communications. In this technique, more copies of the same signal are transmitted through different antennas (space) and different symbol periods (time), to improve the robustness of a wireless system by increasing its diversity gain. STCs are channel coding algorithms that can be readily implemented on a field programmable gate array (FPGA) device. This work provides some figures for the amount of required FPGA hardware resources, the speed that the algorithms can operate and the power consumption requirements of a space-time block code (STBC) encoder. Seven encoder very high-speed integrated circuit hardware description language (VHDL) designs have been coded, synthesised and tested. Each design realises a complex orthogonal space-time block code with a different transmission matrix. All VHDL designs are parameterisable in terms of sample precision. Precisions ranging from 4 bits to 32 bits have been synthesised. Alamouti's STBC encoder design [Alamouti, S.M. (1998), ‘A Simple Transmit Diversity Technique for Wireless Communications’, IEEE Journal on Selected Areas in Communications, 16:55–108.] proved to be the best trade-off, since it is on average 3.2 times smaller, 1.5 times faster and requires slightly less power than the next best trade-off in the comparison, which is a 3/4-rate full-diversity 3Tx-antenna STBC.

Human sound‐localization behaviour after multiple changes in eye position

Orienting the eyes towards a peripheral sound source calls for a transformation of the head-centred sound coordinates into an oculocentric motor command, which requires an estimate of current eye position. Current models of saccadic control explain spatial accuracy by oculocentric transformations that rely on efference copies of relative eye-displacement signals, rather than on absolute eye position in the orbit. In principle, the gaze-control system could keep track of instantaneous eye position by vector addition of intervening eye-displacement commands. However, given that each motor update is endowed with some noise, the neural estimate of eye orientation is then expected to become noisier with increasing number of intervening saccades. As a consequence, the localization response will also be noisier. According to the alternative, in which target updates rely on feedback of the current eye position, such an increase in errors would be absent. In an attempt to dissociate these hypotheses, we studied the influence of the accumulation of oculomotor commands prior to a sound-localization response. Head-restrained subjects generated voluntary eye movements in darkness in random directions for a period between 0.2 and 15 s, after which they rapidly reoriented the eyes towards a brief sound burst. The results demonstrate that the audiomotor system programmes the orienting response on the basis of actual eye position, rather than on an accumulated estimate from intervening eye displacements.