1522 research outputs found
Sort by
Fate of transgenic DNA and protein in pigs fed genetically modified Bt maize and effects on growth and health
Get PDFAbstract The effects of short- and long-term feeding of genetically modified Bt MON810 maize on porcine growth performance and health were investigated in two studies. Bt maize expresses the Cry1Ab toxin from Bacillus thuringiensis which confers insect resistance. Fate of the cry1Ab transgene and Cry1Ab protein were also investigated. Short-term (31 days) feeding of Bt maize to weanling pigs resulted in higher feed intake but overall weight gain and feed conversion efficiency were unaffected. Organ function, as measured by blood biochemistry, organ weight and histology, was unaffected in the Bt group. Minor changes were observed in immune cell population distribution but these were not associated with local or systemic inflammation and there was no Cry1Abspecific immune response. Bt maize consumption had minimal impact on caecal microbial community structure; the only populations affected were Enterococcaceae, Erysipelotrichaceae, Blautia and Bifidobacterium, which were found in low abundance and at low prevalence. The effect of long-term (110 days) feeding of Bt maize to pigs from 12 days post-weaning to slaughter was investigated in a second feeding trial which used a crossover of diets (from isogenic to Bt maize and vice-versa) after 30 days. There were no adverse effects on growth, slaughter parameters, immune response, intestinal histology or microbiology. Organ function was not adversely affected and no histopathology was present. In both short- and long-term studies the transgene was mostly degraded during digestion and neither the transgene nor protein were detected in the blood or organs. Overall, short- or long-term feeding of Bt maize to pigs did not adversely affect any of the growth or health parameters investigated. These findings should provide assurance to pig producers as well as the feed industry of the safety of Bt maize, one of the main ingredients of pig diets. They should also help assure consumers, as a similar lack of adverse effects should be expected in humans, for which pigs are considered an excellent model
Dynamic Shared Groups within XMPP: An Investigation of the XMPP Group Model
Get PDFGroup communication offers a means for resource
sharing and collaboration, often delivered through diverse
technologies. One of the technologies, Instant Messaging,
traditionally took the role of a facilitating service within such
communities. Driven by a flexible XML based protocol, XMPP,
instant messaging has developed functionality to a point where it
can be considered a standalone group communication medium.
Harnessing the extensible nature of the protocol continues to be a
challenge. Alternative usage scenarios not envisioned by its core
group management models have since emerged. This paper
examines the current XMPP group models and how they can
fulfill the requirements of a modern scenario centered on
dynamic shared groups
An experimental testbed to predict the performance of XACML Policy Decision Points
Get PDFThe performance and scalability of access control
systems is a growing concern as organisations deploy ever more complex communications and content management systems. This paper describes how an (offline) experimental testbed may be used to address performance concerns. To begin, timing measurements are collected from a server component incorporating the Policy Decision Point (PDP) under test, using representative policies and corresponding requests. Our experiments with two XACML PDP implementations show that measured request service times are typically clustered by request type; thus an algorithm for request cluster identification is presented. Cluster characterisations are used as inputs to a PDP performance model for a given policy/request mix and an analytic (queueing) model is used to estimate the equilibrium server load for different mixes of request clusters. The analytic performance prediction model is validated and extended by discrete event simulation of a PDP subject to additional load. These predictive models enable network administrators to explore the capacity of the PDP for different overall loadings (requests per unit time) and profiles (relative frequencies) of requests
Adaptive and Tractable Bayesian Context Inference for Resource Constrained Devices
Get PDFContext inference is necessary in ubiquitous computing to provide information about contextual information which is not directly measurable from sensors or obtained from other information sources. Server based, central inference would not scale due to the expected amount of context requests. Mobile, distributed context inference faces problems because of the high computational complexity of inference mechanisms. Bayesian inference techniques are particularly well suited, as they allow for more exible modelling of situations than propositional logic, are always decidable as opposed to higher order logics, are intelligible to humans as opposed to neural networks and allow for uncertain or missing information. As inference in them however is NP-hard, methods have to be introduced to fit them to the requirements of ubiquitous computing and mobile, resource constrained devices. To this end, this work proposes to divide Bayesian networks for context inference into modules, called Bayeslets. Bayeslets can be composed among each other to fulfil an inference request via interface nodes about which additional assumptions are made: Considering input nodes as observed, more efficient inference methods can possibly be applied and by defining explicit output nodes for connection, a relevancy based dynamic composition of Bayeslets can be realised, so the evaluated number of Bayeslets always stays at a minimum. The inference time of Bayeslets can be further reduced by adapting edges and value ranges to the user's personal requirements and the current situation. The application of these concepts is shown in general examples of high level context used in the user's smart space, in his work environment, as well as in road traffic. Experimental results show that this process results in a significant reduction of the inference load. The Bayeslets for location and human motion related activity are of particular importance for context awareness and therefore considered and evaluated in detail. The set of tools proposed in this thesis allows to apply a fully Bayesian approach to context inference, fulfilling the requirements of ubiquitous computing and mobile, resource constrained devices
A Folio of Original Compositions for Various Performing Groups with Detailed Analysis : Volume 1 of 2
Get PDFThe overall aim of this study was to produce a body of original music in a contemporary art-music style, framed within a portfolio of six works. These works are designed to illustrate aspects of my individual style as a composer through the musical techniques employed, the instrumentation chosen and the reflection of my musical influences which emanate through the works themselves. The works included in this portfolio are composed and arranged for a variety of forces, from solo instrumental to large-scale orchestral music. It is my aspiration that this portfolio will demonstrate versatility in my ability to write for assorted combinations of instruments at an appropriate standard.
A detailed analysis of each work accompanies the portfolio. This analysis outlines my aims in writing each piece along with musical concerns I experienced in the process of composition and, at times, how I dealt with or approached these concerns. For each work the pitch source material, compositional devices and instrumentation used in writing this portfolio are discussed under relevant headings.
A CD accompanying this portfolio contains audio representations of the works created by computer software (midi format). As a caveat, it should be noted that the computer’s interpretation of the music is not always entirely representative of the sound that would be produced by the actual performer, however, for all works the advice and consult of a specialist performers, conductors and composers was sought. Some works within the portfolio were performed in a live setting during the course of study however such substantial changes were made to the works which rendered any recordings that were made virtually obsolete. Unfortunately, efforts made to produce live and/or studio recordings of completed works towards the time of submission were rendered impossible due to a lack of available resources
A Note on Narayana Triangles and Related Polynomials, Riordan Arrays, and MIMO Capacity Calculations
Get PDFWe study the Narayana triangles and related families of polynomials. We link this study to Riordan arrays and Hankel transforms arising from a special case of capacity calculation related to MIMO communication systems. A link is established between a channel capacity calculation and a series reversion
Conceptualising firm level innovativeness and its strategic antecedents
No full textDespite the increasing importance attributed to firm level innovativeness within the literature, conceptualising the phenomenon remains a neglected issue. Nevertheless, despite the lack of conceptualisations, the term innovativeness has been widely used in the literature but with a mix of interpretations, and often used interchangeably with its antecedents and its output, innovation. Consequently, the innovativeness concept and its strategic antecedents still lack clarity. This knowledge deficit is also having subsequent effects on practice. Indeed, the lack of a comprehensive conceptualisation means that innovativeness is difficult to achieve and remains a central dilemma for most firms. This study aims to close this knowledge gap by dimensionalising innovativeness and presenting the strategic practices that enhance it and, in so doing, will obtain a diagnostic tool that can be used by firms to assess and improve their level of innovativeness. A systematic review of the literature was utilised to conceptualise innovativeness as a global, multidimensional construct. Adopting a positivistic approach, data was gathered from 500 firms utilising a mail survey, resulting in a 35.7% response rate. The key finding of this research is that innovativeness is a global, multidimensional construct consisting of risk taking, creativity, receptivity and proactiveness. Indeed, the innovativeness construct explained 68.2% of the covariance between these dimensions (first order factors), which indicates that it is the bundling of these dimensions that captures the dynamic nature of the innovativeness capability. In addition, this study also identified that the strategic practices of: leadership consistency, leveraging knowledge processes, and applied leveraging knowledge were the determinants of innovativeness. Finally, it is perceived that the study makes several methodological contributions in the form of scale development and measurement, and provides a significant contribution to practice and academic understanding concerning the nature of innovativeness and the explanatory power of this study’s proposed antecedents to innovativeness
A CONCEPTUALISATION OF PROFESSIONALISM IN TOURISM
Get PDFThe success of the global tourism industry will ultimately depend on its professionalism (Edgell et al., 2008). Tourism professionalism is a multidimensional concept, but lacking consensus on its dimensions; this paper addresses this issue by presenting a conceptualisation of professionalism. This paper extends Hall’s (1968) early work on professionalism, which conceptualised professionalism as involving 5 dimensions. Based on the literature and the tourism context, this paper uniquely argues that there are 10 discriminant dimensions of professionalism. It is perceived that the authors’ study on tourism professionalism will make a significant contribution to the focalised knowledge streams and provide transitional countries with insights into their support, for example, through educational interventions.
Keywords: Professionalism, Conceptual framework, Tourism Educatio