Measuring Latency Variations in Evoked Potential Components Using a Simple Autocorrelation Technique

Interpretation of averaged evoked potentials is difficult when the time relationship between stimulus and response is not constant. Later components are more prone to latency jitter, making them insufficiently reliable for routine clinical use even though they could contribute to greater understanding of the functioning of polysynaptic components of the afferent nervous system. This study is aimed at providing a simple but effective method of identifying and quantifying latency jitter in averaged evoked potentials. Autocorrelation techniques were applied within defined time windows on simulated jittered signals embedded within the noise component of recorded evoked potentials and on real examples of somatosensory evoked potentials. We demonstrated that the technique accurately identifies the distribution and maximum levels of jitter of the simulated components and clearly identifies the jitter properties of real evoked potential recording components. This method is designed to complement the conventional analytical methods used in neurophysiological practice to provide valuable additional information about the distribution of latency jitter within an averaged evoked potential. It will be useful for the assessment of the reliability of averaged components and will aid the interpretation of longer-latency, polysynaptic components such as those found in nociceptive evoked potentials.

A New Perspective on Individual Reliability beyond Group Effects for Event-related Potentials: A Multisensory Investigation and Computational Modeling

The dominant approach in investigating the individual reliability for event-related potentials (ERPs) is to extract peak-related features at electrodes showing the strongest group effects. Such a peak-based approach implicitly assumes ERP components showing a stronger group effect are also more reliable, but this assumption has not been substantially validated and few studies have investigated the reliability of ERPs beyond peaks. In this study, we performed a rigorous evaluation of the test-retest reliability of ERPs collected in a multisensory and cognitive experiment from 82 healthy adolescents, each having two sessions. By comparing group effects and individual reliability, we found that a stronger group-level response in ERPs did not guarantee a higher reliability. Further, by simulating ERPs with a computational model, we found that the consistency between group-level ERP responses and individual reliability was modulated by inter-subject latency jitter and inter-trial variability. The current findings suggest that the conventional peak-based approach may underestimate the individual reliability in ERPs. Hence, a comprehensive evaluation of the reliability of ERP measurements should be considered in individual-level neurophysiological trait evaluation and psychiatric disorder diagnosis.

Self-Heating Hotspots in Superconducting Nanowires Cooled by Phonon Black-Body Radiation

Controlling thermal transport is important for a range of devices and technologies, from phase change memories to next-generation electronics. This is especially true in nano-scale devices where thermal transport is altered by the influence of surfaces and changes in dimensionality. In superconducting nanowire single-photon detectors, the thermal boundary conductance (TBC) between the nanowire and the substrate it is fabricated on influences most of the performance metrics that make these detectors attractive for applications. This includes the maximum count rate, latency, jitter, and quantum efficiency. Despite its importance, the study of TBC in superconducting nanowire devices has not been done systematically, primarily due to the lack of a straightforward characterization method. Here, we show that simple electrical measurements can be used to estimate the TBC between nanowires and substrates and that these measurements match acoustic mismatch theory across a variety of substrates. Numerical simulations allow us to refine our understanding, however, open questions remain. This work should enable thermal engineering in superconducting nanowire electronics and cryogenic detectors for improved device performance.

Modular and scalable automation for field robots

This article describes a modular and scalable charging and navigation concept for electrified field robots and other agricultural machines. The concept consists of an underbody charging system on a trailer and a modular navigation box. The underlying conductive charging process is compared to other charging techniques. Charging time in relation to charging current and mean power consumption in field use is displayed. In the navigation box, data of various sensors are combined by means of multi-sensor fusion regarding the precise time of arrival. Time synchronization is achieved by a novel method for compensating the data latency jitter by employing Kalman-based timestamp filtering. Furthermore, navigation functionalities, such as motion planning and mapping, are presented.

Secure and Guarantee QoS in a Video Sequence: A New Approach Based on TLS Protocol to Secure Data and RTP to Ensure Real-Time Exchanges

Much of the Internet's communication is encrypted, and its content is only accessible at two endpoints, a client and a server. However, any encryption requires a key that must be negotiated without being revealed to potential attackers. The so-called TLS (Transport Layer Security) handshake is often used for this task without obviating that many fundamental parameters of TLS connections are transmitted explicitly. Thus, third parties have access to metadata, including information about the endpoints, how the connection is used. On the other hand, QoS is considered the central part of the communication used to judge the deliverable quality through several parameters (latency, jitter ...). This document describes a secure approach and meets mainly the requirements of quality of service on a communication channel (free, loaded, congested ...), using the robustness and flexibility of the TLS protocol represented on the characteristics of existing encryption keys on its list of "ciphers suites." We focused more particularly on the AES key (Advanced Encryption Standard), including the different sizes (128,192,256), given its resistance to various classical attacks (differential, linear, ...) and its lightness compared to other protocols such as DES, 3DES ... This method is useful in continuous communications in a time axis (video sequence, VOIP call...).

Telematics and Mobile Internet

Telematics technologies and vehicular communications enable various intelligent transportation system applications with different data flow requirements that must be considered by the communications infrastructure provider in terms of transmission reliability, latency, jitter, and security. To meet those requirements, the dynamic nature of traffic and spatiotemporal features of roads must be considered. In parallel with the full coverage in urban areas and increase in the data rates, mobile networks have been started to be widely used by intelligent transportation system applications, especially for gathering data from various sensors. In this chapter, firstly, the current situation of telematics applications for intelligent transportation system is focused on and then mobile internet and mobile internet based applications are reviewed. Second, how much benefit vehicle telematics and mobile internet applications can obtain from the evolution of mobile networks is analysed. Finally, future research directions in this domain are pointed out.

Constrained Average Design Method for QoS-Based Traffic Engineering at the Edge/Gateway Boundary in VANETs and Cyber-Physical Environments

Cyber physical systems (CPSs) are software-intensive smart distributed systems that support physical components endowed with integrated computational capabilities. Tiered, often wireless, networks are typically used to collect or push the data generated or required by a distributed set of CPS-based devices. The edge-to-core traffic flows on the tiered networks can become overwhelming. Thus, appropriate traffic engineering (TE) algorithms are required to manage the flows, while at the same time meeting the delivery requirements in terms of latency, jitter, and packet loss. This chapter provides a basic overview of CPSs followed by a discussion of a newly developed TE method called ‘constrained average', where traffic is by design allowed to be delayed up to a specified, but small value epsilon, but with zero packet loss.