Littérature scientifique sur le sujet « Redundant signals effect »

AbstractEvidence for the influence of unaware signals on behaviour has been reported in both patient groups and healthy observers using the Redundant Signal Effect (RSE). The RSE refers to faster manual reaction times to the onset of multiple simultaneously presented target than those to a single stimulus. These findings are robust and apply to unimodal and multi-modal sensory inputs. A number of studies on neurologically impaired cases have demonstrated that RSE can be found even in the absence of conscious experience of the redundant signals. Here, we investigated behavioural changes associated with awareness in healthy observers by using Continuous Flash Suppression to render observers unaware of redundant targets. Across three experiments, we found an association between reaction times to the onset of a consciously perceived target and the reported level of visual awareness of the redundant target, with higher awareness being associated with faster reaction times. However, in the absence of any awareness of the redundant target, we found no evidence for speeded reaction times and even weak evidence for an inhibitory effect (slowing down of reaction times) on response to the seen target. These findings reveal marked differences between healthy observers and blindsight patients in how aware and unaware information from different locations is integrated in the RSE.

Olfactory integration is important for survival in a natural habitat. However, how the nervous system processes signals of two odorants present simultaneously to generate a coherent behavioral response is poorly understood. Here, we characterize circuit basis for a form of olfactory integration in Caenorhabditis elegans. We find that the presence of a repulsive odorant, 2-nonanone, that signals threat strongly blocks the attraction of other odorants, such as isoamyl alcohol (IAA) or benzaldehyde, that signal food. Using a forward genetic screen, we found that genes known to regulate the structure and function of sensory neurons, osm-5 and osm-1, played a critical role in the integration process. Loss of these genes mildly reduces the response to the repellent 2-nonanone and disrupts the integration effect. Restoring the function of OSM-5 in either AWB or ASH, two sensory neurons known to mediate 2-nonanone-evoked avoidance, is sufficient to rescue. Sensory neurons AWB and downstream interneurons AVA, AIB, RIM that play critical roles in olfactory sensorimotor response are able to process signals generated by 2-nonanone or IAA or the mixture of the two odorants and contribute to the integration. Thus, our results identify redundant neural circuits that regulate the robust effect of a repulsive odorant to block responses to attractive odorants and uncover the neuronal and cellular basis for this complex olfactory task.

Denoising and extraction of the weak signals are crucial to mechanical equipment fault diagnostics, especially for early fault detection, in which cases fault features are very weak and masked by the noise. The wavelet transform has been widely used in mechanical faulty signal denoising due to its extraordinary timefrequency representation capability. However, the mechanical faulty signals are often non-stationary, with the structure varying significantly within each scale. Because a single wavelet filter cannot mimic the signal structure of an entire scale, the traditional wavelet-based signal denoising method cannot achieve an ideal effect, and even worse some faulty information of the raw signal may be lost in the denoising process. To overcome this deficiency, a novel mechanical faulty signal denoising method using a redundant non-linear second generation wavelet transform is proposed. In this method, an optimal prediction operator is selected for each transforming sample according to the selection criterion of minimizing each individual prediction error. Consequently, the selected predictor can always fit the local characteristics of the signals. The signal denoising results from both simulated signals and experimental data are presented and both support the proposed method.

Although the effects of anthropogenic noise on animal communication have been studied widely, most research on the effect of noise in communication has focused on signals in a single modality. Consequently, how multi-modal communication is affected by anthropogenic noise is relatively poorly understood. Here, we ask whether song sparrows ( Melospiza melodia ) show evidence of plasticity in response to noise in two aggressive signals in acoustic and visual modalities. We test two hypotheses: (i) that song sparrows will shift signalling effort to the visual modality (the multi-modal shift hypothesis) and (ii) that they will increase redundancy of their multi-modal signalling (the back-up signal hypothesis). We presented male song sparrows with song playback and a taxidermic mount with or without a low-frequency acoustic noise from a nearby speaker. We found that males did not switch their signalling effort to visual modality (i.e. wing waves) in response to the noise. However, the correlation between warbled soft songs and wing waves increased in the noise treatment, i.e. signals became more redundant. These results suggest that when faced with anthropogenic noise, song sparrows can increase the redundancy of their multi-modal signals, which may aid in the robustness of the communication system.

The redundant-signals effect (RSE) refers to a speed-up of RT when the response is triggered by two, rather than just one, response-relevant target elements. Although there is agreement that in the visual modality RSEs observed with dimensionally redundant signals originating from the same location are generated by coactive processing architectures, there has been a debate as to the exact stage(s)—preattentive versus postselective—of processing at which coactivation arises. To determine the origin(s) of redundancy gains in visual pop-out search, the present study combined mental chronometry with electrophysiological markers that reflect purely preattentive perceptual (posterior-contralateral negativity [PCN]), preattentive and postselective perceptual plus response selection-related (stimulus-locked lateralized readiness potential [LRP]), or purely response production-related processes (response-locked LRP). As expected, there was an RSE on target detection RTs, with evidence for coactivation. At the electrophysiological level, this pattern was mirrored by an RSE in PCN latencies, whereas stimulus-locked LRP latencies showed no RSE over and above the PCN effect. Also, there was no RSE on the response-locked LRPs. This pattern demonstrates a major contribution of preattentive perceptual processing stages to the RSE in visual pop-out search, consistent with parallel-coactive coding of target signals in multiple visual dimensions [Müller, H. J., Heller, D., & Ziegler, J. Visual search for singleton feature targets within and across feature dimensions. Perception & Psychophysics, 57, 1–17, 1995].

Transportation networks are considered one of the critical physical infrastructures for resilient cities (cyber-physical systems). In efforts to minimize adverse effects that come with the advancement of vehicular technologies, various governmental agencies, such as the U.S. Department of Homeland Security and the National Highway Traffic Safety Administration (NHTSA), work together. This paper develops belief-network-based attack modeling at signalized traffic networks under connected vehicle and intelligent signals frameworks. For different types of cyber attacks, defined in the literature, risk areas and impacts of attacks are evaluated. Vulnerability scores, technically based on the selected metrics, are calculated for signal controllers. In addition, the effect of having redundant traffic sensing systems on intersection performance measures is demonstrated in terms of average queue length differences.

This dissertation studies the effects of radiation-induced single-event upsets (SEUs) on digital signal processing (DSP) systems designed for field-programmable gate arrays (FPGAs). It presents a novel method for evaluating the effects of radiation on DSP and digital communication systems. By using an application-specific measurement of performance in the presence of SEUs, this dissertation demonstrates that only 5-15% of SEUs affecting a communications receiver (i.e. 5-15% of sensitive SEUs) cause critical performance loss. It also reports that the most critical SEUs are those that affect the clock, global reset, and most significant bits (MSBs) of computation. This dissertation also demonstrates reduced-precision redundancy (RPR) as an effective and efficient alternative to the popular triple modular redundancy (TMR) for FPGA-based communications systems. Fault injection experiments show that RPR can improve the failure rate of a communications system by over 20 times over the unmitigated system at a cost less than half that of TMR by focusing on the critical SEUs. This dissertation contrasts the cost and performance of three different variations of RPR, one of which is a novel variation developed here, and concludes that the variation referred to as "Threshold RPR" is superior to the others for FPGA systems. Finally, this dissertation presents several methods for applying Threshold RPR to a system with the goal of reducing mitigation cost and increasing the system performance in the presence of SEUs. Additional fault injection experiments show that optimizing the application of RPR can result in a decrease in critical SEUs by as much 65% at no additional hardware cost.

Este trabalho aborda um sistema de aquisição de dados (SAD) analógico-digital, baseado em um esquema redundante com diversidade de projeto, que é testado em dois ambientes diferentes de radiação. O primeiro experimento considera um teste de dose total ionizante (Total Ioninzig Dose - TID) sob irradiação gama, e o segundo experimento considera os efeitos de eventos singulares (Single Event Effects - SEE) sob irradiação por íons pesados. O SAD é composto, principalmente, por três conversores analógicos-digitais (ADCs) e dois votadores. A técnica usada é a Redundância Modular Tripla (Triple Modular Redundancy - TMR), com implementação em diferentes níveis de diversidade (temporal e arquitetural). O sistema é construído em um System-on-Chip programável (PSoC 5LP) da Cypress Semiconductor, fabricado em tecnologia CMOS de 130nm. Para a irradiação com TID, se utiliza o PSoC de part number CY8CKIT-050 sob uma fonte de radiação gama de 60Co (cobalto-60), com uma taxa de dose efetiva de 1 krad(Si)/h por 10 dias, atingindo uma dose total de 242 krad(Si) Para SEE se utiliza o protótipo PSoC de part number CY8CKIT-059 (sem encapsulamento) em um acelerador de partículas 8UD Pelletron usando 16O (oxigeno-16) ao vácuo, com energia de 36 MeV em um LET aproximado de 5.5 MeV/mg/cm2 e uma penetração no silício de 25 mm, resultando em um fluxo de 354 p/cm2.s, e uma fluência de 5077915 p/cm2 depois de 14755 segundos (4h 09min). Observou-se com o resultado do primeiro estudo que um (1) dos módulos do sistema apresentou uma degradação significativa na sua linearidade durante a irradiação, enquanto os outros tiveram uma degradação menos grave, mantendo assim a funcionalidade e confiabilidade do sistema. Durante o tempo de irradiação do segundo estudo, foram observadas 139 falhas: 53 SEFIs (Single Events Funtional Interrupt), 29 falhas críticas e 57 falhas SDC (Silent Data Corruption), atingindo as diferentes copias do sistema e um dos votadores do mesmo, mas sempre mantendo a saída esperada. Nos dois experimentos se evidencia a vantagem de usar a diversidade de projeto, além do TMR, para melhorar a resiliência e confiabilidade em sistemas críticos redundantes que trabalham com sinais mistos.
This work presents an analog-to-digital data acquisition system (DAS) based on a redundant scheme with design diversity, being tested in two different radiation environments. The first experiment is a Total Ionizing Dose (TID) essay and the second one considers Single Event Effects (SEE) under heavy ion irradiation. The DAS is mainly composed of three analog-todigital converters (ADCs) and two voters. The used technique was the Triple Modular Redundancy (TMR) implementing different levels of diversity (temporal and architectural). The circuit was built in a programmable System-on-Chip (PSoC 5LP) from Cypress Semiconductor, fabricated in a 130nm CMOS technology process. For the irradiation with TID the part number CY8CKIT-050 PSoC was used under a 60Co (cobalt-60) gamma radiation source, with an effective dose rate of 1 krad(Si)/h during 10 days, reaching a total dose of 242 krad(Si). For SEE experiments the part number CY8CKIT-059 (without encapsulation) PSoC prototype under a 8UD Pelletron particle accelerator using 16O (oxigen-16) under vacuum, with an energy of 36 MeV, resulting in a flux of 354p/cm2.s and a fluence of 5077915p/cm2 after 14755 seconds (4h 09min). As result of the first study it was observed that one of the system’s modules presented a significant degradation in its linearity during the irradiation, while degradations in the other modules were not as deep, maintaining the system’s functionality and reliability. During the period of the radiation of the second study, 139 faults were observed, 82 of them were critical and 57 were SDC (Silent Data Corruption), reaching the different system copies and one of the voters, while always maintaining the correct output. The advantage of using diversity, besides TMR, to improve resilience and reliability in redundant systems working with mixed signals was demonstrated in both experiments.

DISSOCIAZIONE CONSAPEVOLE-INCONSAPEVOLE NELLA PERCEZIONE VISIVA: INDIZI DA PAZIENTI EMIANOPTICI. Lesioni lungo la via visiva producono difetti caratteristici nel campo visivo. Il tipo più comune di disturbo del campo visivo omonimo (HVFD) è l’emianopsia. La probabilità del verificarsi di HVFDs in seguito ad ictus, trauma o intervento è elevata, circa il 20-30 %. Nei pazienti con HVFDs sono seriamente compromesse le attività quotidiane a causa della disabilità acquisita in nell’orientamento visivo e di esplorazione spaziale. Il recupero della funzione visiva è possibile, ma è raramente completo. Tuttavia, negli anni settanta del secolo scorso Poeppel et al e successivamente Weiskrantz et al hanno descritto la presenza di comportamento guidato dalla visione nel campo cieco di pazienti emianopsici (“blindsight”). Questa Tesi è incentrata sul tentativo di gettare nuova luce su questo importante fenomeno. In particolare, lo scopo del presente progetto di ricerca è molteplice: i) si propone di studiare le implicazioni del concetto di numerosità e di percezione Gestaltica nei normali e il ruolo di queste caratteristiche nel fenomeno del Blindsight in pazienti con emianopsia ; ii) vuole indagare le proprietà psicofisiche della visione residua (consapevole e inconsapevole) nel campo cieco e iii ) si propone di studiare l'anatomia e la funzionalità degli emisferi intatti e danneggiati attraverso l’uso dell’elettroencefalografia e della neuroimmagine funzionale. Nel primo progetto, abbiamo impiegato il paradigma di ridondanza del segnale (RSE), in soggetti normali ed in pazienti emianopsici, al fine di indagare le caratteristiche percettive dell’emicampo intatto e cieco, e l'interazione tra loro. Come prima cosa, abbiamo testato 18 partecipanti sani (età media : 31.1 ) per osservare se la RSE aumenta con 4 vs 1 stimoli. Abbiamo usato due differenti configurazioni di stimoli, nella prima i quattro stimoli formano una figura gestalt simile a una forma di diamante, mentre nell'altra la posizione degli stimoli è stata randomizzata. Ai partecipanti era richiesto di mantenere la fissazione su un piccolo stimolo centrale e, dopo l’arrivo di un segnale acustico, dovevano premere un pulsante il più rapidamente possibile alla presentazione degli stimoli visivi. I risultati hanno mostrato un aumento della RSE (cioè più rapidi tempi di reazione) quando gli stimoli erano quadrupli rispetto a quando erano singoli, indipendentemente dalla configurazione proposta. Un’ulteriore analisi ha mostrato che l’RSE con stimoli semplici e con stimoli che formano una configurazione Gestaltica è spiegata da una coattivazione neurale, piuttosto che da una teoria probabilistica, in quanto si osserva una violazione del modello di Miller. Al contrario, il risultato ottenuto nella presentazione di stimuli quadrupli in posizione randomizzata potrebbe essere spiegabile alla luce di una teoria probabilistica. Nella seconda parte, abbiamo studiato se tale paradigma modificato era più efficace nel rilevare il fenomeno del Blindsight (un comportamento inconscio guidato visivamente) in pazienti emianoptici e nei pazienti emisferectomizzati. Abbiamo testato sei pazienti con emianopsia (età media : 45,83 ) a seguito di lesione del tratto corticale o ottico e un paziente emisferectomizzato. La procedura era la stessa dell’esperimento precedente. I risultati hanno mostrato una maggiore efficacia del metodo con stimoli numerosi, tenendo conto della misurazione della RSE con più stimoli presentati contemporaneamente nell’emicampo intatto e cieco rispetto alla presentazione singola nel campo intatto. È interessante notare che la RSE nei pazienti era più pronunciata per la configurazione gestaltica. Inoltre i risultati osservati con l’analisi di risonanza magnetica funzionale hanno mostrato un'attivazione di aree visive localizzate a livello della via visiva ventrale. Nel secondo progetto, ci siamo proposti di capire quale dei due emisferi media il comportamento guidato visivamente dopo la presentazione di stimoli nell’emicampo cieco di pazienti con emianopsia. Abbiamo testato 9 pazienti (età media : 44.5 ) con il paradigma di Poffenberger ( PP ): si tratta di un compito di Tempo di Reazione che prevede la presentazione dello stimolo visivo lateralizzato e una risposta unimanuale. I risultati hanno mostrato che nell’emicampo intatto tutti i pazienti mostrano una CUD positiva (cioè normale) mentre i risultati nell’emicampo cieco erano più variabili con una CUD positiva in alcuni pazienti e negativa in altri. Quest’ultimo dato significa che la risposta nel campo cieco era mediata dall’emisfero intatto e questo potrebbe essere correlato alla estensione delle singole lesioni. Inoltre, abbiamo usato un nuovo metodo per indagare il Blindsight, abbiamo confrontato le frequenze di distribuzione cumulative (CDF) dei temi di reazione a seguito della presentazione dello stimolo nel campo intatto e cieco in condizioni normali e con gli occhi chiusi. Abbiamo testato 6 pazienti di cui due mostrano il fenomeno del blindsight mentre ad occhi chiusi non c’erano risposte sopra al caso. Infine, abbiamo usato la risonanza magnetica funzionale (fMRI) per valutare il coinvolgimento delle specifiche strutture cerebrali in IT delle informazioni visuo-motorie e il ruolo dell’emisfero intatto. Abbiamo testato il ben noto paziente con blindsight GY con il paradigma di Poffenberger . I risultati comportamentali hanno registrato una CUD positiva quando il paziente era stimolato visivamente nel campo intatto, e una CUD negativa quando stimolato nel campo cieco, suggerendo che sia l'emisfero intatto a mediare il blindsight. I risultati dell’analisi funzionale hanno mostrato l'attivazione di aree corticali (aree visive ventrali , aree visive dorsali, aree senso- motorie e premotorie) e le aree del corpo calloso, differenziato nella condizione di stimolazione consapevole e inconsapevole (anteriore vs medio -posteriore, rispettivamente). Nel terzo progetto, abbiamo misurato la risposta elettrofisiologica alla stimolazione visiva del campo visivo cieco e intatto sempre nel paradigma di Poffenberger (PP) in 12 soggetti sani e in tre pazienti emianoptici. Lo scopo dell'indagine è stato quello di indagare sulla natura e la funzionalità dell'emisfero leso, così come cercare di capire l'efficienza della trasmissione inter-emisferica. In entrambi gli emisferi abbiamo trovato una assenza di risposta ERP per la stimolazione del campo cieco mentre per la stimolazione dell’ emicampo intatto abbiamo trovato una buona risposta diretta nell'emisfero controlaterale. È interessante notare una risposta differente nei tre pazienti per la risposta commissurale indiretta. Infatti, la risposta registrata nell'emisfero lesionato è assente o molto debole in siti posteriori per il paziente EA e il paziente PC, mentre per la paziente SL la risposta registrata nell'emisfero leso era paragonabile a quella dei soggetti sani. Ciò sembrerebbe suggerire che il trasferimento interemisferico e l'integrazione di informazioni visive tra l’emisfero danneggiato e quello intatto dei pazienti emianoptici sembra avvenire nella fase percettiva e necessita dell'integrità funzionale e anatomica dello splenium del Corpo Calloso. In breve, l’interesse dell’intera ricerca è multiplo. In primo luogo, utilizzando il RSE si è constatato che vi è una sostanziale interazione tra i due emisferi nei pazienti e che la visione inconscia è sensibile alla numerosità e mostra una sorta di organizzazione percettiva gestaltica. In secondo luogo, ho descritto i risultati di un nuovo metodo per registrare la presenza di abilità residue di rilevamento di stimoli inconsci nei pazienti emianoptici, probabilmente innescato da antiche aree evolutive sottocorticali. Infine, utilizzando il paradigma di Poffenberger, con l’uso delle registrazioni ERP e della neuroimmagine, è stato possibile avere indizi utili a capire l'importanza dell'emisfero intatto nella mediazione della visione cieca.
CONSCIOUS – UNCONSCIOUS DISSOCIATIONS IN VISUAL PERCEPTION: CLUES FROM HEMIANOPIC PATIENTS. Lesions along the visual pathway produce characteristic gaps in the visual field. The most common type of homonymous field disorder (HVFD) is hemianopia. The probability of occurrence of HVFDs following a stroke, trauma or surgery is high, around 20-30%. Patients with HVFDs are seriously impaired in everyday activities and this is because of the acquired disability in visual orienting and exploration. Recovery of visual function is possible but is rarely complete. However, in the seventies of last century it has been shown by Poeppel et al. and subsequently by Weiskrantz et al. that some hemianopic patients retain some form of visually guided behaviour in the blind hemifield in absence of perceptual awareness (“blindsight”). This Thesis is mainly based on casting new light on this intriguing phenomenon. In particular, the purpose of the present research project is multifold: i) To investigate whether higher-order perceptual effects like Numerosity detection and Gestalt phenomena are present in the blind hemifield of hemianopic patients; ii) To investigate the basic psychophysical properties of conscious as well as unconscious (blindsight) residual vision in the blind field and iii) To study the anatomy and functionality of the intact and damaged hemispheres through electrophysiological recordings and functional imaging. In the first project, we employed a redundant signal effect (RSE) paradigm, in healthy participants and in patients, to investigate the perceptual characteristics of the intact and blind hemifield, and the interaction between them. Initially, we tested in healthy participants whether the RSE increases with 4 vs 1 stimuli. We used two different configurations of stimuli, in one the four redundant stimuli formed a gestalt-like figure in the shape of a diamond, while in the other the position of stimuli was randomized. We tested 18 participants (mean age: 31.1). They were required to keep their fixation steady on a central fixation point and, following onset of an acoustic warning signal, to press a button as quickly as possible upon presentation of the visual stimuli. Results showed an increase of the RSE (i.e. faster reaction times) with four with respect to single stimuli independently from the configuration proposed. The analysis of the present data showed that the RSE effect in the Single bilateral presentation and in the Quadruple Gestalt bilateral presentation is attributable to neural coactivation rather than probability summation, in that there was a violation of Miller’s race inequality. Conversely, the result obtained in the Quadruple Random bilateral presentation was attributable to a probability summation, in that there was no violation of the race inequality. In the second part of this project, we investigated if this procedure was more likely to increase the probability to detect blindsight in hemianopic patients and in hemisperectomized patients. We tested six patients with hemianopia (mean age: 45.83) as a result of cortical or optic tract lesion and one hemisperectomized patient. The procedure and design were the same as in the previous experiment. The results showed a trend toward an increase of speed of reaction time as measured by the RSE with multiple stimuli presented simultaneously to the intact and blind hemifield in comparison to stimuli to the intact field only. It is interesting to point out that the RSE in hemianopics and in the hemisperectomized patient was more pronounced for the gestalt-like configuration and this suggests the presence of gestalt-like perception in blindsight and provides important clues for rehabilitation. Moreover the functional magnetic resonance imaging results showed as expected an activation of visual areas localized at the level of the ventral visual pathway. In the second project, we tried to understand which of the two hemispheres mediates visually guided behavior following stimulus presentation to the blind hemifield of patients with hemianopia. We tested 9 patients (mean age:44.5) with the Poffenberger paradigm (PP): a RT task that involves a lateralized visual stimulus presentation in the intact and in the blind hemifield and a unimanual response. The crossed-uncrossed difference (CUD), a behavioural estimate of callosal interhemispheric transfer (IT) time for stimuli presented to the intact hemifield of all patients was positive and this can be interpreted as related to the lesioned hemisphere subserving the response whilst in the blind hemifield the results were more variable with some patients showing a positive and others a negative CUD (i.e. the response was subserved by the intact hemisphere) and this could be related to the extension of the individual lesions. In the second part, we used a new method for testing blindsight, namely to compare the cumulative distribution frequency (CDF) of RT for stimulus presentation to the intact and the blind field under normal or occluded viewing conditions. We tested 6 patients and the results were that two of them showed blindsight. We also used functional magnetic resonance (fMRI) to assess the involvement of specific brain structures in the IT of visuomotor information and the role of the intact hemisphere. We tested with the Poffenberger paradigm the well known blindsight patient GY. Behavioural results showed a positive CUD for the stimulation of the intact hemifield, and a negative CUD for the stimulation of the blind hemifield, suggesting that the intact hemisphere mediates the blindsight responses. Functional results showed activation of cortical areas (ventral visual areas, dorsal visual areas, sensori-motor and premotor areas) and callosal areas, with interesting differences in the conscious and unconscious conditions (anterior vs. middle-posterior, respectively). In the third project, we measured the electrophysiological response to visual stimulation of blind and intact visual field in the Poffenberger Paradigm (PP) in 12 healthy subjects and in three hemianopic patients. The purpose of the investigation was to inquire into the nature and the functionality of the lesioned hemisphere as well as try to understand the efficiency of IT. In both hemispheres we found an absence of ERP responses for stimulation of the hemianopic field while for stimulation of the intact hemifield we found a good direct response in the contralateral hemisphere. Interestingly, we observed a different response in the three patients for the indirect commissural response: the response recorded in the lesioned hemisphere was absent or very weak in posterior sites for patient EA and patient PC while for patient SL the response recorded in the lesioned hemisphere was comparable to that of healthy participants. This suggests that IT and integration of visual information from the intact to the damaged hemisphere of hemianopic patients seems to occur at the perceptual stage depending on the functional and anatomical integrity of the splenium of the CC. In short, the thrust of this entire Thesis is multifold. First, by using the Redundant Signal Effect it was found that there is a substantial cross-talk between the two hemispheres in hemianopic patients, including one hemispherectomy patient, and that unconscious vision is sensitive to stimulus numerosity and shows a sort of gestaltic perceptual organization. Second, I described the results of a new method to assess a reliable detection of unconscious stimuli in hemianopic patients probably triggered by evolutionary ancient subcortical areas. Finally, by using the Poffenberger paradigm, associated or not with ERP recordings, it was possible to have clues as to the importance of the intact hemisphere in mediating blindsight.

The landmark paper discussed in this chapter, published by Calignano et al. in 1998, focuses on the control of pain initiation by endogenous cannabinoids. In the paper, analgesic lipid mediators are shown to be present in peripheral paw tissue where they control the ability of pain signals to ascend to the central nervous system (CNS). Anandamide acts through a peripheral mechanism to suppress inflammatory pain via cannabinoid type 1 receptors. Palmitoylethanolamine, subsequently identified as an endogenous ligand for peroxisome proliferator-activated receptor-α‎, produces peripheral antinociceptive effects via a mechanism similar to that for the cannabinoid type 2 receptor. These lipids do not serve redundant functions and, in combination, produce synergistic antinociceptive effects. These observations suggested that drug-development efforts targeting peripheral control of pain may elucidate improved pharmacotherapies that lack the unwanted CNS side effects of current treatments.

The Thesis is concerned with assessing the suitability of LTE (4G) cellular networks for the remote control of low-flying UAVs. To solve this problem, an approach to the analysis of the delay values in cellular networks has been developed, which makes it possible to estimate the delays of individual cells and overall cellular network. Requirements for delays in the UAV control channel were developed, conclusions were drawn about the suitability of the LTE network as a communication solution for the UAV remote control. A method for calculating the effect of parallel redundancy is proposed, and an experimental assessment of the possibility of using two existing solutions for parallel redundancy in LTE networks is carried out. In addition, a compact technical solution for analyzing the level of base station signals was demonstrated.

Lamina circuits are designed to transfer information effectively and efficiently from photoreceptors to interneurons in the face of two neural constraints: limited dynamic range and synaptic noise. The design uses analogue signals to achieve high information rates, high gain synapses releasing vesicles at high rate to reduce the effects of synaptic noise, and predictive coding to remove redundancy. To increase synaptic efficiency predictive coding is implemented pre-synaptically, using unorthodox non-vesicular mechanisms. To optimize information uptake, the lamina circuit continuously adapts to input statistics over a wide range of input levels. The lamina circuit demonstrates a widely employed circuit motif because its equivalent, in the vertebrate retina’s outer plexiform layer (OPL) has similar properties. The motif’s functional advantages were established in lamina because it is more amenable to reverse engineering. Indeed, the fly lamina exemplifies several principles of neural design that apply widely throughout brains.

Abstract One of the more visible signs of organizational restructuring is that many firms have become flatter on the organizational chart. In search of efficiencies, some of them have removed entire layers of management to speed up communication and reduce headcount. So far so good. But what often ends up roiling the water is the prospect of employee redundancy (HP, which is headed for a split, may cut around 55,000 jobs globally), redeployments, and job separation as a company gets into the restructuring mode. A review of literature on spin-offs and demergers seems to suggest that a split in business can be organizationally disruptive as it can cause stress and broken bonds between employees who feel vulnerable and not in control of their careers. Given this, experts suggest corporate leaders must ask some fundamental questions before embarking on a demerger exercise: How can the company work to minimize the human impact of a demerger while remaining competitive? Indeed, how does the psychological contract between the worker and the employer change post a split? Above all, how can the workforce be motivated to perform better after the split? It must be understood that regardless of whether an organization conceptualizes and designates its spin-off as re-engineering or reorganization of business, the adoption and implementation of workforce reorientation strategies will inexorably produce considerable financial, organizational, and emotional effects. While some such outcomes can be anticipated and are tangible, others have unexpected, long-term consequences that are difficult to measure.

Cable-suspended robots are structurally similar to parallel actuated robots but with the fundamental difference that cables can only pull the end-effector but not push it. From a scientific point of view, this feature makes feedback control of cable-suspended robots lot more challenging than their counterpart parallel actuated robot. In this paper, we look into control design for a non-redundant cable-suspended robot under positive input constraints. The design is based on feedback linearization controllers augmented with reference signal management. Reference signal management operates in accordance with the receding horizon strategy, by generating admissible reference signals which makes system not to violate the input constraints. An important issue in implementing predictive horizon algorithm for nonlinear systems is to predict the system behavior in a computationally efficient way. We show that feedback linearization controllers with reference signal management can offer an efficient way to predict the system’s future states, using the error dynamics of inner feedback loop. Finally, the effectiveness of the proposed method is illustrated by numerical simulation and laboratory experiments on a six degree-of-freedom suspended cable robot.

Cable-based robots generally perform better than other parallel robots with rigid links in terms of wider workspace and higher acceleration of end effector because of lightweight of robot links. Cable based robots allow an easy mounting and remounting for outside applications; however, this requires a precise assembly of components at the cable anchor points. In this study, firstly a parametric model is developed for estimation of position errors of anchor points for fully-constrained and redundant planar cable robots. A novel method based on inclusion of virtual cables facilitates the linear separation of the uncertain parameters from the input-output signals for redundant planar robots. In addition, the adaptive law (parameter estimator) updates the estimated parameters using the least squares algorithm. The simulation results show that the least squares method reduces the time of estimation convergence compared to gradient algorithms. Furthermore, the least squares method allows simple persistent excitation signals to estimate parameters.

A series of tests in a small-scale loop containing a centrifugal pump was carried out to develop practical acoustic test and analysis techniques to be used in a manufacturer’s pump test facility during pump qualification testing. To determine the pump transmission characteristics, the effect of high noise levels due to the flow was reduced by driving an external source repeatedly with a swept-frequency signal and performing synchronous, time-domain averaging. A new multi-sensor technique is shown to provide accurate estimates of the pump acoustic transfer matrix. Results confirm that the pump transfer matrix is similar whether the pump is running or not. This indicates that the full-scale pump transfer matrix may be determined with the pump off using a relatively weak external acoustic source and a pump loop system with no cavitation.

Abstract Swing phase of the human gait is defined as the time period during the bottom of foot is off the ground. At the beginning of swing phase there is a flexion of knee joint, which is important to form the clearance between the ground and the toe. In 1992 Winter referred to that the average clearance is about 1.29cm in a normal swing phase and mainly dominated by the flexion of the knee joint. If there doesn’t have enough flexion of knee, the tiptoe will collide with the ground during the swing phase. Otherwise, in this case, there must be an additional trunk movement to raise the coxa joint or to abduct the thigh. Actually this is not a normal gait and looks very clumsy as you can imagine a patient’s gait. However, regarding how to obtain the enough flexion of knee, people have different views on that whether the muscles of lower limb are actively involved and how much contribution they make. Mochaon and McMahon (1980) stated that at a certain extent of initial angular velocity, the clearance can be obtained without muscles’ involving. Mena (1981) also referred to that an approximated normal swing phase could be simulated without applying moments on the coxa joint and/or knee joint. But later, researchers got different results. Yamaguchi (1990) found that there should be muscular forces in swing phase through a simulation analysis of 8-DOF musculoskeletal model with dynamic programming method. With limiting solution method. Collins (1995) got the similar conclusion. In 1996. Piazza and Delp presented a 3-DOF musculoskletetal model to study the effects of muscular forces on knee flexion, they decreased or increased the strength of the neural innervation signals of some muscles and made a thorough observation on the movement of lower limbs. In their discussions the importance of rectus femoris (RF) in knee flexion was emphasized.

Wireless sensors used in plant floor environments have been studied for obstruction and multipath propagation effects on signal quality. The trend towards wireless industrial data networks motivates this study, which explores the use of IEEE 802.15.1 radios in a machine shop at varying levels of operation. Previous studies have investigated the use of a wireless sensor embedded in a rotating tool holder to monitor tool life. In order to obtain information furthering the potential use of low power radio in conjunction with machining enclosures, a Bluegiga WT12 Class 2 Bluetooth 2.1 module is placed within several CNC machining enclosures at varying table positions and heights. An exterior module receives the data from the enclosed unit, and the module’s position is also varied in 3 dimensional space. Bit Error Rate and Received Signal Strength are measured, and the effects of spatial obstruction and multipath propagation are analyzed. An Agilent 8563E spectrum analyzer equipped with an Aaronia HyperLOG 7060 EMC antenna is also used to repeat the measurements at all of the points in order to provide EMI channel characterization and a redundant source of signal power data for comparison. Large-area transmissibility testing indicates that received signal strength is not dependent upon equipment operation. The enclosure tests (perimeter, height, and proximity comparison) suggest that distance, both static and transient path obstructions, multipath propagation, and line-of-sight are factors that influence bit error rate and received signal strength. Spectrum analyzer measurements in our shop show no significant emissions in the 2.4 GHz range that cause interference. At no time during this study did the bit error rate reach 0.2% of the transmitted bits and there were no failures in transmitting text between modules. Overall, the findings indicate that reliable data transmission with low power off-the-shelf Bluetooth modules is feasible.

Cyber-physical systems consist of interconnected physical processes and computational resources. Because the cyber and physical worlds are integrated, the system’s physical assets are vulnerable to cyber-attack. An attacker who is able to access control inputs and mask measurements can damage the system while remaining undetected. By masking certain measurement signals, an attacker may render part of the state space unobservable, meaning that it is impossible to reconstruct those states. This is called an observability attack. A game-theoretic approach is presented to analyze observability attacks. The attacker’s strategy set includes all possible combinations of masked measurements. The defender’s strategy set includes redundant sensing and direct measurement of state variables. Attacker and defender payoffs are quantified using the responses of the observable and unobservable states. The observability attack game is analyzed for a nuclear balance of plant system. Combinations of sensor omissions are analyzed to find observability attacks with high impact and low detection. The effects of sensor augmentation are examined. A pure strategy Nash equilibrium is identified.

Abstract Due to their manifold application possibilities, shape memory alloys (SMA) become more and more common in all kinds of industrial tasks. For an operation in mass-manufactured products, it is inevitable to investigate the fundamental properties of the respective material and to perfect the fabrication process. A potential use of SMAs in aerospace is even more demanding, since the testing and qualification is quite complex, and the components are solely built in small batch series. In order to prove possible approaches for manufacturing, for this paper several specimens of two generations of an intelligent redundant spacecraft actuator were assembled. Evaluating the intrinsic effect of SMA-wires, it was possible to detect signs of fatigue in the material and realize preventive maintenance. Beside a description of the manufacturing steps of both generations, the test results are presented in detail and it can be concluded that the second generation is, due to its design, more suitable for a serial production as well as more robust and efficient. It is shown that over the lifetime of the actuator the properties of the SMA-material are continuously changing.

The New York City Transit (NYCT) Signal Modernization Program has been ongoing since the mid-1990s. The current phase of modernization involves the procurement of Solid State Interlocking (SSI) systems that are designed to replace relay-based interlockings. SSI procurement has necessitated significant adjustments to NYCT’s system deployment processes, most notably in the areas of design, implementation, test, maintenance, and safety certification. NYCT has successfully met the challenge of applying the updated deployment processes to multiple, concurrent system procurements. The most fundamental change to the NYCT procurement approach required a shift from the traditional design-build model of acquisition for relay-based systems to a software-based development lifecycle for SSIs. The relay-based Interlocking systems’ design-build model has traditionally involved the realization of complex relay logic with well-known hardware components such as relays, trip-stops, signals and switch machines. The SSI systems’ software model however requires additional consideration of software and hardware development phases, such as designated in the V-lifecycle. V-model phases include requirement, design, implementation, and test. For SSI systems, NYCT adopted a “double” V-Life cycle approach, one V for the supplier’s SSI hardware and software (executive) platform, and one V for the SSI application (site-specific field) logic. At NYCT, the first V is dedicated to the suppliers’ executive platform. Hardware and software comprising the supplier platform are verified to meet safety and performance requirements. Safety analyses such as Fault Tree Analysis, Failure Modes and Effects Analysis, Timing Analysis, and Hazard Analysis are generated by SSI suppliers. System Safety Concepts, e.g., Numerical Assurance, Checked Redundancy, Intrinsic Fail-Safety are also assessed. NYCT’s second V is dedicated to the application software, i.e., the site-specific relay-based logic, which is implemented as Boolean logic within the SSI. For the Booleans, the process of traditional circuit checking is supplemented by Model Checking, wherein NYCT General Safety Properties are used to verify the site-specific logic. Model Checking provides assurance that safety properties are met throughout the entire interlocking design, for every system state, and does not rely on a manual review process. This paper will focus on the benefits NYCT has realized as a result of adopting Model Checking as a requirement for safety certification, along with an overview of the NYCT SSI safety certification process.

Many phytopathogenic bacteria use a type III protein secretion system (T3SS) to inject type III effectors into plant cells. In the experiments supported by this one-year feasibility study we investigated type III effector function in plants by using two contrasting bacterial pathogens: Pseudomonas syringae pv. tomato, a necrotrophic pathogen and Pantoea agglomerans, a tumorigenic pathogen. The objectives are listed below along with our major conclusions, achievements, and implications for science and agriculture. Objective 1: Compare Pseudomonas syringae and Pantoea agglomerans type III effectors in established assays to test the extent that they can suppress innate immunity and incite tumorigenesis. We tested P. agglomerans type III effectors in several innate immunity suppression assays and in several instances these effectors were capable of suppressing plant immunity, outputs that are suppressed by P. syringae effectors. Interestingly, several P. syringae effectors were able to complement gall production to a P. agglomerans pthGmutant. These results suggest that even though the disease symptoms of these pathogens are dramatically different, their type III effectors may function similarly. Objective 2: Construct P. syringae mutants in different combinations of type III-related DNA clusters to reduce type III effector redundancy. To determine their involvement in pathogenicity we constructed mutants that lack individual and multiple type III-related DNA clusters using a Flprecombinase-mediated mutagenesis strategy. The majority of single effector mutants in DC3000 have weak pathogenicity phenotypes most likely due to functional redundancy of effectors. Supporting this idea, Poly-DNAcluster deletion mutants were more significantly reduced in their ability to cause disease. Because these mutants have less functional redundancy of type III effectors, they should help identify P. syringae and P. agglomerans effectors that contribute more significantly to virulence. Objective 3: Determine the extent that P. syringae and P. agglomerans type III effectors alter hormone levels in plants. Inhibition of auxin polar transport by 2,3,5-triiodobenzoic acid (TIBA) completely prevented gall formation by P. agglomerans pv. gypsophilae in gypsophila cuttings. This result supported the hypothesis that auxin and presumably cytokinins of plant origin, rather than the IAA and cytokinins secreted by the pathogen, are mandatory for gall formation. Transgenic tobacco with pthGshowed various phenotypic traits that suggest manipulation of auxin metabolism. Moreover, the auxin levels in pthGtransgenic tobacco lines was 2-4 times higher than the control plants. External addition of auxin or cytokinins could modify the gall size in gypsophila cuttings inoculated with pthGmutant (PagMx27), but not with other type III effectors. We are currently determining hormone levels in transgenic plants expressing different type III effectors. Objective 4: Determine whether the P. agglomerans effectors HsvG/B act as transcriptional activators in plants. The P. agglomerans type III effectors HsvG and HsvB localize to the nucleus of host and nonhost plants and act as transcription activators in yeast. Three sites of adjacent arginine and lysine in HsvG and HsvB were suspected to act as Nuclear localization signals (NLS) domains. A nuclear import assay indicated two of the three putative NLS domains were functional NLSs in yeast. These were shown to be active in plants by fusing HsvG and HsvB to YFP. localization to the nucleus was dependent on these NLS domains. These achievements indicate that our research plan is feasible and suggest that type III effectors suppress innate immunity and modulate plant hormones. This information has the potential to be exploited to improve disease resistance in agricultural crops.