Ultrasonic motion analysis system - measurement of temporal and spatial gait parameters

The duration of stance and swing phase and step and stride length are important parameters in human gait. In this technical note a low-cost ultrasonic motion analysis system is described that is capable of measuring these temporal and spatial parameters while subjects walk on the floor. By using the propagation delay of sound when transmitted in air, this system is able to record the position of the subjects' feet. A small ultrasonic receiver is attached to both shoes of the subject while a transmitter is placed stationary on the floor. Four healthy subjects were used to test the device. Subtracting positions of the foot with zero velocity yielded step and stride length. The duration of stance and swing phase was calculated from heel-strike and toe-off. Comparison with data obtained from foot contact switches showed that applying two relative thresholds to the speed graph of the foot could reliably generate heel-strike and toe-off. Although the device is tested on healthy subjects in this study, it promises to be extremely valuable in examining pathological gait. When gait is asymmetrical, walking speed is not constant or when patients do not completely lift their feet, most existing devices will fail to correctly assess the proper gait parameters. Our device does not have this shortcoming and it will accurately demonstrate asymmetries and variations in the patient's gait. As an example, the recording of a left hemiplegic patient is presented in the discussion. (C) 2002 Elsevier Science Ltd. All rights reserved

A Proof of the Isoenergetic KAM-Theorem from the “Ordinary” One

A proof is given of the isoenergetic KAM-theorem for Hamiltonian systems, using the “ordinary” KAM-theorem and a transversality argument.

A Service Component-based Accounting and Charging Architecture to Support Interim Mechanisms across Multiple Domains

Today, telematics services are often compositions of different chargeable service components offered by different service providers. To enhance component-based accounting and charging, the service composition information is used to match with the corresponding charging structure of a service session. This enables the sharing of revenues among the service providers, and calculation of the total cost for the end-user. When multiple independent service providers are involved, it is a great challenge to apply interim accounting and charging during a service session in order to minimize financial risks between business partners. Another interesting development is the trend towards outsourcing accounting and charging processes to specialized business partners. This requires a decoupling between provisioning and accounting and charging processes. In this paper, we propose a comprehensive component-based accounting and charging architecture to support service session provisioning across multiple domains. The architecture, modeled in UML, incorporates an interim accounting and charging mechanism to enable the processing and exchange of accounting information needed to update intermediate charges for separate service components and the user's credit, even during the service provisioning phase

Developing web crawlers for vertical search engines: a survey of the current research

Vertical search engines allow users to query for information within a subset of documents relevant to a pre-determined topic (Chakrabarti, 1999). One challenging aspect to deploying a vertical search engine is building a Web crawler that distinguishes relevant documents from non-relevant documents. In this research, we describe and analyze various methods to crawl relevant documents for vertical search engines, and we examine ways to apply these methods to building a local search engine. In a typical crawl cycle for a vertical search engine, the crawler grabs a URL from the URL frontier, downloads content from the URL, and determines the document’s relevancy to the pre-defined topic. If the document is deemed relevant, it is indexed and its links are added to the URL frontier. Two questions are raised in this process: how do we judge a document’s relevance, and how should we prioritize URLs in the frontier in order to reach the best documents first? To determine the relevancy of a document, we may hold on to a set of pre-determined keywords that we attempt to match in a crawled document’s content and metadata. Another possibility is to use relevance feedback, a mechanism where we train the crawler to spot relevant documents by feeding it training data. In order to prioritize links within the URL frontier, we can use a breadth-first crawler where we just index pages one level at a time, bridges which are pages that aren’t crawled but used to gather more links, reinforcement learning where the crawler is rewarded for reaching relevant pages, and decision trees where the priority given to a link depends on the quality of the parent page

Experiments in climate governance – lessons from a systematic review of case studies in transition research

Experimentation has been proposed as one of the ways in which public policy can drive sustainability transitions, notably by creating or delimiting space for experimenting with innovative solutions to sustainability challenges. In this paper we report on a systematic review of articles published between 2009 and 2015 that have addressed experiments aiming either at understanding decarbonisation transitions or enhancing climate resilience. Using the case survey method, we find few empirical descriptions of real-world experiments in climate and energy contexts in the scholarly literature, being observed in only 25 articles containing 29 experiments. We discuss the objectives, outputs and outcomes of these experiments noting that explicit experimenting with climate policies could be identified only in 12 cases. Based on the results we suggest a definition of climate policy experiments and a typology of experiments for sustainability transitions that can be used to better understand the role of and learn more effectively from experiments in sustainability transitions

QUIC-FEC: Bringing the benefits of Forward Erasure Correction to QUIC

Originally implemented by Google, QUIC gathers a growing interest by providing, on top of UDP, the same service as the classical TCP/TLS/HTTP/2 stack. The IETF will finalise the QUIC specification in 2019. A key feature of QUIC is that almost all its packets, including most of its headers, are fully encrypted. This prevents eavesdropping and interferences caused by middleboxes. Thanks to this feature and its clean design, QUIC is easier to extend than TCP. In this paper, we revisit the reliable transmission mechanisms that are included in QUIC. More specifically, we design, implement and evaluate Forward Erasure Correction (FEC) extensions to QUIC. These extensions are mainly intended for high-delays and lossy communications such as In-Flight Communications. Our design includes a generic FEC frame and our implementation supports the XOR, Reed-Solomon and Convolutional RLC error-correcting codes. We also conservatively avoid hindering the loss-based congestion signal by distinguishing the packets that have been received from the packets that have been recovered by the FEC. We evaluate its performance by applying an experimental design covering a wide range of delay and packet loss conditions with reproducible experiments. These confirm that our modular design allows the protocol to adapt to the network conditions. For long data transfers or when the loss rate and delay are small, the FEC overhead negatively impacts the download completion time. However, with high packet loss rates and long delays or smaller files, FEC allows drastically reducing the download completion time by avoiding costly retransmission timeouts. These results show that there is a need to use FEC adaptively to the network conditions.Comment: 9 pages, presented at IFIP Networking 201

Nuclear processes associated with plant immunity and pathogen susceptibility

Plants are sessile organisms that have evolved exquisite and sophisticated mechanisms to adapt to their biotic and abiotic environment. Plants deploy receptors and vast signalling networks to detect, transmit and respond to a given biotic threat by inducing properly dosed defence responses. Genetic analyses and, more recently, next-generation -omics approaches have allowed unprecedented insights into the mechanisms that drive immunity. Similarly, functional genomics and the emergence of pathogen genomes have allowed reciprocal studies on the mechanisms governing pathogen virulence and host susceptibility, collectively allowing more comprehensive views on the processes that govern disease and resistance. Among others, the identification of secreted pathogen molecules (effectors) that modify immunity-associated processes has changed the plant–microbe interactions conceptual landscape. Effectors are now considered both important factors facilitating disease and novel probes, suited to study immunity in plants. In this review, we will describe the various mechanisms and processes that take place in the nucleus and help regulate immune responses in plants. Based on the premise that any process required for immunity could be targeted by pathogen effectors, we highlight and describe a number of functional assays that should help determine effector functions and their impact on immune-related processes. The identification of new effector functions that modify nuclear processes will help dissect nuclear signalling further and assist us in our bid to bolster immunity in crop plants

How Nutritional and Genetic Factors affect New Zealand Goat Milk Composition

Demand for goat milk produced in New Zealand (NZ) is rapidly growing, particularly in expanding Asian markets. The aim of this study was to investigate how genetic and nutritional factors influence milk composition of NZ dairy goats. Little is known about these two factors in dairy goats, especially when compared to extensive research conducted in the area on dairy cows. Therefore in an attempt to improve goat milk production and composition, one important gene and three common nutritional supplements were investigated as part of this study. The gene CSN1S1 was chosen for genetic analysis as it is highly polymorphic and can produce a range of effects on milk composition. 126 dairy goats were genotyped and 100 of these were aligned to herd-test and fatty acid data. Key findings include (a) ‘medium’ and ‘low’ CSN1S1 variants are the most common in the NZ dairy goat population, (b) CSN1S1 genotype significantly influences milk protein content, (c) in some circumstances CSN1S1 genotype can affect milk yield and fat content (d) CSN1S1 genotype has no effect on somatic cell count or the kilograms yielded of fat and protein or milk solids and (e) CSN1S1 genotypes produce small differences in two fatty acids (C10:0 and C18:3n3). Due to their increasing popularity as alternative animal feeds, palm kernel extract (PKE), biscuit waste (BW) and yeast nutritional factors were investigated. PKE significantly increased C12:0 and C14:0 fatty acids which were reduced to control-farm levels following removal of the supplement in the next season. BW had no clear effects on milk fatty acid composition while yeast supplementation had no effect on any aspect of milk composition. Significant seasonal effects were observed for some fatty acids. Overall this research has shown that milk produced from NZ dairy goats has the potential to be modified through genetic and dietary means. Genetic factors such as CSN1S1 and nutritional supplements, especially PKE can alter milk composition. The healthfulness of goat milk can therefore be optimised to better suit the nutritional needs of the consumer