Stop Failure Research Articles

Early Rise and Persistent Inhibition of Electromyography during Failed Stopping.

Reactively canceling movements is a vital feature of the motor system to ensure safety. This behavior can be studied in the laboratory using the stop-signal task. There remains ambiguity about whether a "point-of-no-return" exists, after which a response cannot be aborted. A separate question concerns whether motor system inhibition associated with attempted stopping persists when stopping is unsuccessful. We address these two questions using electromyography (EMG) in two stop-signal task experiments. Experiment 1 (n = 24) involved simple right and left index finger responses in separate task blocks. Experiment 2 (n = 28) involved a response choice between the right index and pinky fingers. To evaluate the approximate point of no return, we measured EMG in responding fingers during the 100 msec preceding the stop signal and observed significantly greater EMG amplitudes during failed than successful stopping in both experiments. Thus, EMG before the stop signal differentiated success, regardless of whether there was a response choice. To address whether motor inhibition persists after failed stopping, we assessed EMG peak-to-offset durations and slopes (i.e., rate of EMG decline) for go, failed stop, and successful stop (partial response) trials. EMG peak-to-offset was shorter and steeper for failed stopping compared to go and successful stop partial response trials, suggesting motor inhibition persists even when failing to stop. These findings indicate EMG is sensitive to a "transition zone" at which the relative likelihood of stop failure versus success inverts and also suggest peak-to-offset time of response-related EMG activity during failed stopping reflects stopping-related inhibition.

Low blood concentration of alcohol enhances activity related to stopping failure in the right inferior frontal cortex.

This study investigated the effects of low doses of alcohol, which are acceptable for driving a car, on inhibitory control and neural processing using the stop-signal task (SST) in 17 healthy right-handed social drinkers. The study employed simultaneous functional magnetic resonance imaging and electromyography (EMG) recordings to assess behavioral and neural responses under conditions of low-dose alcohol (breath-alcohol concentration of 0.15mg/L) and placebo. The results demonstrated that even a small amount of alcohol consumption prolonged Go reaction times in the SST and modified stopping behavior, as evidenced by a decrease in the frequency and magnitude of partial response EMG that did not result in button pressing during successful inhibitory control. Furthermore, alcohol intake enhanced neural activity during failed inhibitory responses in the right inferior frontal cortex, suggesting its potential role in behavioral adaptation following stop-signal failure. These findings suggest that even low levels of alcohol consumption within legal driving limits can greatly impact both the cognitive performance and brain activity involved in inhibiting responses. This research provides important evidence on the neurobehavioral effects of low-dose alcohol consumption, with implications for understanding the biological basis of impaired motor control and decision-making and potentially informing legal guidelines on alcohol consumption.

The effect of staircase stopping accuracy and testing environment on stop-signal reaction time.

The stop-signal task is widely used in experimental psychology and cognitive neuroscience research, as well as neuropsychological and clinical practice for assessing response inhibition. The task requires participants to make speeded responses on a majority of trials, but to inhibit responses when a stop signal appears after the imperative cue. The stop-signal delay after the onset of the imperative cue determines how difficult it is to cancel an initiated action. The delay is typically staircased to maintain a 50% stopping accuracy for an estimation of stopping speed to be calculated. However, the validity of this estimation is compromised when participants engage in strategic slowing, motivated by a desire to avoid stopping failures. We hypothesized that maintaining stopping accuracy at 66.67% reduces this bias, and that slowing may also be impacted by the level of experimenter supervision. We found that compared with 50%, using a 66.67% stopping accuracy staircase produced slower stop-signal reaction time estimations (≈7 ms), but resulted in fewer strategic slowing exclusions. Additionally, both staircase procedures had similar within-experiment test-retest reliability. We also found that while individual and group testing in a laboratory setting produced similar estimations of stopping speed, participants tested online produced slower estimates. Our findings indicate that maintaining stopping accuracy at 66.67% is a reliable method for estimating stopping speed and can have benefits over the standard 50% staircase procedure. Further, our results show that care should be taken when comparing between experiments using different staircases or conducted in different testing environments.

Incorporating Practical Degree of Saturation in Capacity Estimation of On-Street, Mid-Block, Off-Line Bus Stops

The effectiveness of an on-street bus facility depends on the general traffic that shares the lane used by buses. The Transit Capacity and Quality of Service Manual (TCQSM) methodology was used to estimate facility bus capacity based on critical stop operation. Hisham et al. provided an improved understanding of performance of an on-street, mid-block, off-line bus stop by relating bus stop capacity to the adjacent lane traffic flow rate. Using the TCQSM methodology, bus stop capacity was determined by adopting an estimated operation margin that relates to a design bus stop failure rate. However, failure rate is theoretically ambiguous and difficult to quantify in practice, particularly under high volume traffic conditions. In contrast, degree of saturation is a direct measure of operating conditions experienced by buses using the stop, and by the adjacent lane general traffic, so it directly affects approach delay and queuing. The aim of this study was to better understand performance at on-street, mid-block, off-line bus stops by considering degrees of saturation of loading areas and the adjacent lane rather than design failure rate according to the TCQSM methodology, and to ensure that waiting times upstream of bus stops are kept to acceptable levels by determining bus stop maximum working capacity.

Nonlinear model of cascade failure in weighted complex networks considering overloaded edges

Considering the elasticity of the real networks, the components in the network have a redundant capacity against the load, such as power grids, traffic networks and so on. Moreover, the interaction strength between nodes is often different. This paper proposes a novel nonlinear model of cascade failure in weighted complex networks considering overloaded edges to describe the redundant capacity for edges and capture the interaction strength of nodes. We fill this gap by studying a nonlinear weighted model of cascade failure with overloaded edges over synthetic and real weighted networks. The cascading failure model is constructed for the first time according to the overload coefficient, capacity parameter, weight coefficient, and distribution coefficient. Then through theoretical analysis, the conditions for stopping failure cascades are obtained, and the analysis shows the superiority of the constructed model. Finally, the cascading invulnerability is simulated in several typical network models and the US power grid. The results show that the model is a feasible and reasonable change of weight parameters, capacity coefficient, distribution coefficient, and overload coefficient can significantly improve the destructiveness of complex networks against cascade failure. Our methodology provides an efficacious reference for the control and prevention of cascading failures in many real networks.

Characteristics Analysis of Bus Stop Failure Using Automatic Vehicle Location Data

Queue forming behind a bus stop on an urban street is common and a traffic bottleneck usually occurs around the bus stop area. The bus stop failure means arriving buses cannot move into the bus stop due to limited capacity but have to wait for available loading areas. It is related with the transit operation level. Traditionally, the failure rate (FR), defined as the percentage of buses that arrives at the bus stop to find all loading areas occupied, is adopted in bus capacity analysis. However, the concept of FR is unable to quantitatively analyze failure characteristics in terms of its dispersion and uncertainty over time. Therefore, in this paper, we propose a new index called failure duration rate (FDR) to evaluate the bus stop failure, which can characterize waiting time for traffic delay calculation and capacity drop estimation. The automatic vehicle location data at eight bus stops in Wujiang District Suzhou, China, over 56 working days, are used to analyze the temporal characteristics of FR and FDR. We next examined the failed service duration characteristics during peak hours at the eight bus stops. Based on these characteristics analyses, we then proposed a Distribution Fitting and Cumulative Distribution Correlation (DF-CDC) approach to explore the correlation between FDR and FR at the same cumulative distribution function levels and validated the bus stop failure performance using the cross-validation method. The analysis results revealed that (i) FR fluctuates more significant than FDR, (ii) FDR is a more robust index than FR in describing the traffic characteristics incurred by bus stop failures, and (iii) FDR performs better in failure characteristics analysis than FR.

Method of improving the functional dependability of the control systems of an unmanned aerial vehicle in flight in case of failure in the onboard test instrumentation

The Aim of this paper consists in the development of a method of improving the functional dependability of the control systems of unmanned aerial vehicles (UAV CS) affected by electromagnetic effects in flight and failures within the functional component of the onboard test instrumentation (OBTI).That is achieved through the identification of the failed functional element, the functional component of OBTI, the capability of performing the target objective of the UAV CS and decision-making regarding the initiation of the flexible operation algorithm. The existing and future UAV CS under development use binary reliability models, i.e. two states are distinguished: up and disabled. Therefore, each in-flight failure is classified as the UAV CS failure regardless of the current mission. If we regard a CS as a multifunctional system, it becomes obvious that the failure of not any UAV CS functional element causes flight termination. Methods. Solving the problem involved the use of a CS diagnostic model in the form of binary relations between the control actions and combinatorial subsets of functional elements, risk of losses estimation method as part of improving the functional dependability of UAV CS in flight, decision theory and combined branch-and-bound method. The mission performance probability is used as the efficiency criterion. This criterion is applicable when changes in a UAV CS’ characteristics cause only partial reduction of the functional efficiency. Results. The purpose of CBTI self-supervision is failure location with the depth that allows determining its ability to perform the basic operations with the probability not lower than required by the customer, as well as the allowed set of elementary checks (EC) in this case. Based on the current results of elementary self-checks (ESC), one of the following decisions can be taken: stop the checks and discard CBTI; continue location; stop failure location and continue UAV CS mission per modified algorithm. At each stage of failure location in CBTI, based on the results of ESC, the area of covering check (ACC) and part of set suspected of failure (PSSF) are analyzed, which includes verifying the ACC for sufficient coverage of the PSSF, based on which appropriate decisions are taken. The following areas are formed: the area of observable data (processes of changes in the ACC and PSSF areas), within which the decision is taken to continue the checks, and the area, within which it is finally decided to terminate the checks. If It Is decided to continue the failure location, another ESC is selected, which Is associated with the risk of loss. The probability of false discarding of CBTI due to ESC selected out of ACC Is taken as the risk of loss. The moment of termination of CBTI self-supervision depends not only on the set of decisions, but their sequence as well. Thus, the task at hand comes down to designing the optimal ESC strategy that minimizes the probability of false discarding. The idea of combined branch-and-bound method (CBBM) as part of the design of the optimal CBTI self-supervision algorithm consists in the consecutive selection at each stage of ESC implementation process, out of the subset of minimum risk checks of the next ESC till a one-element subset is obtained and/or the corresponding decision is taken. Conclusions. The developed method allows continuing the performance of the target objectives of a UAV CS In flight when affected by failures In CBTI.

Strategy for stopping failure cascades in interdependent networks

Interdependencies are ubiquitous throughout the world. Every real-world system interacts with and is dependent on other systems, and this interdependency affects their performance. In particular, interdependencies among networks make them vulnerable to failure cascades, the effects of which are often catastrophic. Failure propagation fragments network components, disconnects them, and may cause complete systemic failure. We propose a strategy of avoiding or at least mitigating the complete destruction of a system of interdependent networks experiencing a failure cascade. Starting with a fraction 1−p of failing nodes in one network, we reconnect with a probability γ every isolated component to a functional giant component (GC), the largest connected cluster. We find that as γ increases the resilience of the system to cascading failure also increases. We also find that our strategy is more effective when it is applied in a network of low average degree. We solve the problem theoretically using percolation theory, and we find that the solution agrees with simulation results.

Resisting distraction and response inhibition trigger similar enhancements of future performance

Resisting distraction and response inhibition are crucial aspects of cognitive control. Interestingly, each of these abilities transiently improves just after it is utilized. Competing views differ, however, as to whether utilizing either of these abilities (e.g., resisting distraction) enhances future performance involving the other ability (e.g., response inhibition). To distinguish between these views, we combined a Stroop-like task that requires resisting distraction with a restraint variant of the stop-signal task that requires response inhibition. We observed similar sequential-trial effects (i.e., performance enhancements) following trials in which participants (a) resisted distraction (i.e., incongruent go trials) and (b) inhibited a response (i.e., congruent stop trials). First, the congruency effect in go trials, which indexes overall distractibility, was smaller after both incongruent go trials and congruent stop trials than it was after congruent go trials. Second, stop failures were less frequent after both incongruent go trials and congruent stop trials than after congruent go trials. A control experiment ruled out the possibility that perceptual conflict or surprise engendered by occasional stop signals triggers sequential-trial effects independent of stopping. Thus, our findings support a novel, integrated view in which resisting distraction and response inhibition trigger similar sequential enhancements of future performance.

Cooperative Watchdog in Wireless Ad-Hoc Networks

For fault-tolerant wireless ad-hoc networks, detection and notification of failure of intermediate wireless nodes are critical. Until now, various failure detection and notification methods for recovery such as timeout and watchdog have been proposed for stop failure and Byzantine failure restricted to different data message transmissions. In order to avoid desperate cases such that correctly working wireless intermediate nodes are inappropriately taken away from the wireless multihop transmission routes due to malicious failure notification, this paper proposes a novel cooperative watchdog method. Here, not only the previous-hop intermediate wireless nodes as in the conventional watchdog method but also another neighbor wireless node observe transmissions of both data messages and control messages such as failure notification to detect failure of an intermediate wireless node. This paper also proposes an ad-hoc routing protocol to determine both a sequence of intermediate wireless nodes and additional observing wireless nodes for the cooperative watchdog.

Separate neural systems for behavioral change and for emotional responses to failure during behavioral inhibition.

To analyze the involvement of different brain regions in behavioral inhibition and impulsiveness, differences in activation were investigated in fMRI data from a response inhibition task, the stop-signal task, in 1709 participants. First, areas activated more in stop-success (SS) than stop-failure (SF) included the lateral orbitofrontal cortex (OFC) extending into the inferior frontal gyrus (ventrolateral prefrontal cortex, BA 47/12), and the dorsolateral prefrontal cortex (DLPFC). Second, the anterior cingulate and anterior insula (AI) were activated more on failure trials, specifically in SF versus SS. The interaction between brain region and SS versus SF activations was significant (P = 5.6 * 10-8 ). The results provide new evidence from this "big data" investigation consistent with the hypotheses that the lateral OFC is involved in the stop-related processing that inhibits the action; that the DLPFC is involved in attentional processes that influence task performance; and that the AI and anterior cingulate are involved in emotional processes when failure occurs. The investigation thus emphasizes the role of the human lateral OFC BA 47/12 in changing behavior, and inhibiting behavior when necessary. A very similar area in BA47/12 is involved in changing behavior when an expected reward is not obtained, and has been shown to have high functional connectivity in depression. Hum Brain Mapp 38:3527-3537, 2017. © 2017 Wiley Periodicals, Inc.

Investigating motor initiation and inhibition deficits in patients with Parkinson’s disease and freezing of gait using a virtual reality paradigm

Freezing of gait (FOG) is a common, disabling symptom of Parkinson’s disease (PD) that is associated with deficits in motor initiation and inhibition. Understanding of underlying neurobiological mechanisms has been limited by difficulties in eliciting and objectively characterizing such gait phenomena in the clinical setting. However, recent work suggests that virtual reality (VR) techniques might offer the potential to study motor control. This study utilized a VR paradigm to explore deficits in motor initiation and stopping performance, including stop failure in PD patients with (Freezers, 31) and without (Non-Freezers, 23) FOG, and healthy age-matched Controls (15). The VR task required subjects to respond to a series of start and stop cues while navigating a corridor using ankle flexion/extension movements on foot pedals. We found that Freezers experienced slower motor output initiation and more frequent start hesitations (SHs) (initiations greater than twice a subject’s usual initiation latency) compared to Non-Freezers and Controls. Freezers also showed more marked inhibitory impairments, taking significantly longer to execute motor inhibition, and experiencing an increased frequency of failed stopping in response to stop cues compared to Non-Freezers and Controls. Stopping impairments were exacerbated by stop cues requiring additional cognitive processing. These results suggest that PD patients with FOG have marked impairments in motor initiation and inhibition that are not prominent in patients without FOG, nor healthy controls. Future work combining such VR paradigms with neuroimaging techniques and intra-operative deep brain recordings may increase our understanding of these phenomena, promoting the development of novel technologies and therapeutic approaches.

Monotonic Abstraction Techniques: from Parametric to Software Model Checking

Monotonic abstraction is a technique introduced in model checking parameterized distributed systems in order to cope with transitions containing global conditions within guards. The technique has been re-interpreted in a declarative setting in previous papers of ours and applied to the verification of fault tolerant systems under the so-called "stopping failures" model. The declarative reinterpretation consists in logical techniques (quantifier relativizations and, especially, quantifier instantiations) making sense in a broader context. In fact, we recently showed that such techniques can over-approximate array accelerations, so that they can be employed as a meaningful (and practically effective) component of CEGAR loops in software model checking too.

Long-Term Deformation Analysis of the Jiudianxia Concrete-Faced Rockfill Dam

Creep deformation of rockfills affects anti-see page systems, such as concrete face, toe slab, and peripheral joint. In particular, it may cause structure damage, such as water stop failure and concrete face cracking, especially in a high concrete-faced rockfill dam (CFRD) on a deep overburden layer. In this paper, viscoelastic constitutive models for concrete materials and bedrocks (a new creep constitutive model for rockfills) are introduced. A comprehensive study method on the stress and deformation of a high rockfill dam on a deep overburden layer is established based on field plate loading tests, laboratory triaxial creep tests, and prototype monitoring data analysis. The long-term deformation characteristics of Jiudianxia CFRD with complex topography and geological characteristics are analyzed and forecasted by using three-dimensional nonlinear finite element model analysis considering the effect of creep. The deformation of the dam shows an evident increment compared with that without considering the creep effect. Rockfill creep obviously influences the deformation and stress of the concrete-face slab. Meanwhile, comparative study of numerical calculation results and monitoring data showed good agreement between the computed settlements and measured values. Overall, the creep model and the adopted parameters are demonstrated to be reasonable, and the deformation of Jiudianxia CFRD is basically stable.

An Experimental Analysis of Drivers Attitudes towards In-Vehicle Warning System at Stop Sign Controlled Intersection

Most traffic accidents occur at unsignalized intersections, mainly due to inappropriate behavior of non-priority vehicles. The authors have developed an advanced Intelligent Speed Adaptation (ISA) system with GPS/GIS to provide warning to stop failure vehicles at unsignalized intersections. In this study, experiments related to driver attitudes toward stop sign warning were carried out. At a drivers training course, drivers attitudes were tested using a vehicle equipped with the warning system in order to ascertain appropriate timing of warnings when approaching intersections. The drivers evaluation and willingness-to-pay for the warning system were also analyzed using an interview survey answered by testers.

The impossibility of boosting distributed service resilience

We study f-resilient services, which are guaranteed to operate as long as no more than f of the associated processes fail. We prove three theorems asserting the impossibility of boosting the resilience of such services. Our first theorem allows any connection pattern between processes and services but assumes these services to be atomic (linearizable) objects. This theorem says that no distributed system in which processes coordinate using f-resilient atomic objects and reliable registers can solve the consensus problem in the presence of f + 1 undetectable process stopping failures. In contrast, we show that it is possible to boost the resilience of some systems solving problems easier than consensus: for example, the 2-set-consensus problem is solvable for 2 n processes and 2 n - 1 failures (i.e., wait-free) using n-process consensus services resilient to n - 1 failures (wait-free). Our proof is short and self-contained. We then introduce the larger class of failure-oblivious services. These are services that cannot use information about failures, although they may behave more flexibly than atomic objects. An example of such a service is totally ordered broadcast. Our second theorem generalizes the first theorem and its proof to failure-oblivious services. Our third theorem allows the system to contain failure-aware services, such as failure detectors, in addition to failure-oblivious services. This theorem requires that each failure-aware service be connected to all processes; thus, f + 1 process failures overall can disable all the failure-aware services. In contrast, it is possible to boost the resilience of a system solving consensus using failure-aware services if arbitrary connection patterns between processes and services are allowed: consensus is solvable for any number of failures using only 1-resilient 2-process perfect failure detectors. As far as we know, this is the first time a unified framework has been used to describe both atomic and non-atomic objects, and the first time boosting analysis has been performed for services more general than atomic objects.

小交差点での路上設置型装置による一時停止警告に対する運転挙動の実験分析

This study aims to develop a stop failure warning system from road-side for avoiding crossing accidents at small unsignalized junctions. A warning device will be attached to road reflecting mirror for giving warning to vehicle approaching junctions. Is this study, an experiment for analysis of drive's sense and driving behavior when the equipped giving warning to non-priority vehicle and priority vehicle. As of result, in the first experience of warning for each driver, about half of tester noticed the warning that means 80% of drivers will notice of it in case of warning to both non-priority and priority approaches. After the drivers comprehended warning meaning, ratio of braking reaction increases and reacting time was shorten. From the result, inducement on driver's action according to irradiance warnings will be realized.

Mechanism of stress cracking of poly(ethylene terephthalate) beverage bottles: A method for the prevention of stress cracking based on water hardness

A recently described bottle test method was used to evaluate the dependence of stress crack failure of poly(ethylene terephthalate) (PET) carbonated soft drink bottles on water hardness. Although the industry belief is that water hardness is irrelevant to stress cracking, it was found that hardness ions exert a tremendous positive impact by deactivating water alkalinity through precipitation as harmless carbonate minerals. This mitigating effect of hardness means that no complete understanding of stress cracking as a function of alkalinity is possible without also considering water hardness. A useful concept is that of excess alkalinity, which is defined as alkalinity that is not precipitated during solution evaporation. Limiting excess alkalinity by using water with sufficient hardness is an effective means of stress crack prevention in PET soft drink bottles. Evaluation of compositions which are typical of those used for lubricating PET bottles on production conveyors showed that the role of these compositions in stress cracking was that of spectators, that is, they neither cause failure if water does not otherwise cause it, nor stop failure if water otherwise causes it.

Disorder‐specific dysfunction in right inferior prefrontal cortex during two inhibition tasks in boys with attention‐deficit hyperactivity disorder compared to boys with obsessive–compulsive disorder

Inhibitory dysfunction is a key behavioral and cognitive phenotype of attention-deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). Both disorders show neuropsychological deficits and fronto-striatal dysfunction during tasks of motor response inhibition and cognitive flexibility. This study investigates differences and commonalities in functional neural networks mediating inhibitory control between adolescents with ADHD and those with OCD to identify disorder-specific neurofunctional markers that distinguish these two inhibitory disorders. Event-related fMRI was used to compare brain activation between 20 healthy boys, 18 (Stop task) or 12 boys (Switch task) with ADHD, and 10 boys with OCD during a tracking Stop task that measures inhibition and stopping failure and during a visual-spatial switching task measuring cognitive flexibility. Both patient groups shared brain dysfunction compared to healthy controls in right orbitofrontal (successful inhibition) and left dorsolateral prefrontal cortices (failed inhibition). Right inferior prefrontal dysfunction, however, was disorder-specific to ADHD during both tasks. Left inferior prefrontal dysfunction during the Switch task was significant in children with ADHD relative to controls, but only reached a trend in patients with OCD. Patients with ADHD furthermore showed disorder-specific dysfunction in left basal ganglia and cingulate gyrus during the Switch task. Patients with ADHD compared to those with OCD have both common and distinct dysfunctions during inhibitory control. The most consistently reported functional abnormality in children with ADHD in right inferior prefrontal cortex during inhibitory control appears to be disorder-specific when compared to patients with OCD and may be a specific neurofunctional biomarker of ADHD.

An Analysis of Vehicles' Behavior in Approaching to Small Intersections Aiming at Distinction of Stop Failure Vehicle from Road Side

This study proposed distcriminant models which can recognize dangerous approaching vehicles by using their position and speed which can be measured from road side sensors. It aims to develop road side warning facilities for collision avoidance at small unsignalized junctions. According to the analysis of vehicle behavior approaching to junctions, it is found that 90% of stopping vehicles begin their braking during 30m and 10m from the junction, and the beginning point is influence by the width of street on which they are moving. From results of discriminant analysis between dangerous approaching vehicles and safe approaching vehicles using speed and change of speed variables as explanation indices, it is clarified that around 90% of samples would be distinguished correctly and appropriate sensing areas referring to street's width were found.