Escalating The War On SPAM Through Practical POW Exchange

Proof-of-work (POW) schemes have been proposed in the past. One prominent system is HASHCASH (Back, 2002) which uses cryptographic puzzles . However, work by Laurie and Clayton (2004) has shown that for a uniform proof-of-work scheme on email to have an impact on SPAM, it would also be onerous enough to impact on senders of "legitimate" email. I suggest that a non-uniform proof-of-work scheme on email may be a solution to this problem, and describe a framework that has the potential to limit SPAM, without unduly penalising legitimate senders, and is constructed using only current SPAM filter technology, and a small change to the SMTP (Simple Mail Transfer Protocol). Specifically, I argue that it is possible to make sending SPAM 1,000 times more expensive than sending "legitimate" email (so called HAM). Also, unlike the system proposed by Debin Liu and Jean Camp (2006), it does not require the complications of maintaining a reputation system.Comment: To be presented at the IEEE Conference On Networking, Adelaide, Australia, November 19-21, 200

Scribing the writer: implications of the social construction of writer identity for pedagogy and paradigms of written composition

A thesis submitted to the University of Bedfordshire, in partial fulfilment of the requirements for the degree of Doctor of Philosophy by Published Works.A reflexive analysis of five peer reviewed published papers reveals how socio-cultural and political discourses and individual agency compete to shape the identity of the learner-writer. It is posited that although hegemonic political discourses construct ‘schooling literacy’ (Meek 1988 ) which frame the socio-cultural contexts in which texts, authors, teachers and leaners develop; the socio-cultural standpoint of the individual makes possible conscious construction of counter discourses. Writer identity is integral to the compositional process. However, writer identity is mediated by, on the one hand, dominant discourses of literacy that inform current pedagogies of writing (Paper One) and on the other by socio-cultural narratives that shape identity (Paper Three). A synthesis of Gramsci’s notion of cultural hegemony and Bronfenbrenner’s ecological systems theory is used to explain the constraining function of dominant discourses in literacy education. These works largely fall within a qualitative paradigm, although a mixed-method approach was adopted for the data collection of Papers Four and Five. The methods these papers had in common were the use of survey and documentary analysis of reflective journals. A semi-structured interview with a focus group was the third method used to collect data for Paper Five. Individual semi-structured interviews were used to collect partial life-histories for Paper Two and textual analysis of pupils’ narrative writing was the main method used for Paper One. Paper Three involved a rhizotextual auto-ethnographic analysis of original poetry. Findings suggest pedagogies which minimise or negate the identity of the writer are counter-productive in facilitating writer efficacy. It is suggested, the teaching of writing should be premised on approaches that encourage the writer to draw upon personal, inherited and secondary narratives. In this conceptualisation of writing, the writer is simultaneously composing and exploring aspects of self. However, the self is not a fixed entity and writing is viewed as a process by which identity emerges through reflexive engagement with the compositional process. The corollary is that pedagogy of writing needs to embrace the identity of the writer, whilst also allowing space for the writer’s ‘becoming’

On Novel Approaches to Model-Based Structural Health Monitoring

Structural health monitoring (SHM) strategies have classically fallen into two main categories of approach: model-driven and data-driven methods. The former utilises physics-based models and inverse techniques as a method for inferring the health state of a structure from changes to updated parameters; hence defined as inverse model-driven approaches. The other frames SHM within a statistical pattern recognition paradigm. These methods require no physical modelling, instead inferring relationships between data and health states directly. Although successes with both approaches have been made, they both suffer from significant drawbacks, namely parameter estimation and interpretation difficulties within the inverse model-driven framework, and a lack of available full-system damage state data for data-driven techniques. Consequently, this thesis seeks to outline and develop a framework for an alternative category of approach; forward model-driven SHM. This class of strategies utilise calibrated physics-based models, in a forward manner, to generate health state data (i.e. the undamaged condition and damage states of interest) for training machine learning or pattern recognition technologies. As a result the framework seeks to provide potential solutions to these issues by removing the need for making health decisions from updated parameters and providing a mechanism for obtaining health state data. In light of this objective, a framework for forward model-driven SHM is established, highlighting key challenges and technologies that are required for realising this category of approach. The framework is constructed from two main components: generating physics-based models that accurately predict outputs under various damage scenarios, and machine learning methods used to infer decision bounds. This thesis deals with the former, developing technologies and strategies for producing statistically representative predictions from physics-based models. Specifically this work seeks to define validation within this context and propose a validation strategy, develop technologies that infer uncertainties from various sources, including model discrepancy, and offer a solution to the issue of validating full-system predictions when data is not available at this level. The first section defines validation within a forward model-driven context, offering a strategy of hypothesis testing, statistical distance metrics, visualisation tools, such as the witness function, and deterministic metrics. The statistical distances field is shown to provide a wealth of potential validation metrics that consider whole probability distributions. Additionally, existing validation metrics can be categorised within this fields terminology, providing greater insight. In the second part of this study emulator technologies, specifically Gaussian Process (GP) methods, are discussed. Practical implementation considerations are examined, including the establishment of validation and diagnostic techniques. Various GP extensions are outlined, with particular focus on technologies for dealing with large data sets and their applicability as emulators. Utilising these technologies two techniques for calibrating models, whilst accounting for and inferring model discrepancies, are demonstrated: Bayesian Calibration and Bias Correction (BCBC) and Bayesian History Matching (BHM). Both methods were applied to representative building structures in order to demonstrate their effectiveness within a forward model-driven SHM strategy. Sequential design heuristics were developed for BHM along with an importance sampling based technique for inferring the functional model discrepancy uncertainties. The third body of work proposes a multi-level uncertainty integration strategy by developing a subfunction discrepancy approach. This technique seeks to construct a methodology for producing valid full-system predictions through a combination of validated sub-system models where uncertainties and model discrepancy have been quantified. This procedure is demonstrated on a numerical shear structure where it is shown to be effective. Finally, conclusions about the aforementioned technologies are provided. In addition, a review of the future directions for forward model-driven SHM are outlined with the hope that this category receives wider investigation within the SHM community

Survey and Systematization of Secure Device Pairing

Secure Device Pairing (SDP) schemes have been developed to facilitate secure communications among smart devices, both personal mobile devices and Internet of Things (IoT) devices. Comparison and assessment of SDP schemes is troublesome, because each scheme makes different assumptions about out-of-band channels and adversary models, and are driven by their particular use-cases. A conceptual model that facilitates meaningful comparison among SDP schemes is missing. We provide such a model. In this article, we survey and analyze a wide range of SDP schemes that are described in the literature, including a number that have been adopted as standards. A system model and consistent terminology for SDP schemes are built on the foundation of this survey, which are then used to classify existing SDP schemes into a taxonomy that, for the first time, enables their meaningful comparison and analysis.The existing SDP schemes are analyzed using this model, revealing common systemic security weaknesses among the surveyed SDP schemes that should become priority areas for future SDP research, such as improving the integration of privacy requirements into the design of SDP schemes. Our results allow SDP scheme designers to create schemes that are more easily comparable with one another, and to assist the prevention of persisting the weaknesses common to the current generation of SDP schemes.Comment: 34 pages, 5 figures, 3 tables, accepted at IEEE Communications Surveys & Tutorials 2017 (Volume: PP, Issue: 99

Crataegus Series Rotundifoliae In Southwestern Ontario: Patterns Of Morphometric Variation In An Agamic Complex

The thesis defended in this dissertation asserts that individuals of Crataegus series Rotundifoliae (Rosaceae, Maloideae) in southwestern Ontario are members of an agamic complex and that the complex patterns of morphometric variation displayed by the series are a consequence of the reproductive behavior of agamic complexes. The specific problem addressed here arises out of a recognition that the longstanding taxonomic difficulty encountered in the series (and in the genus) can only be solved through intensive cytological, histological and numerical study of local populations.;Cluster Analysis, using a combination of resemblance measure-cluster method combinations, revealed the presence of four groups in a collection of 112 randomly sampled individuals evaluated for 29 morphological descriptors. These four groups and the populations into which they were subdivided display wide differences in levels of variability (univariate descriptor variances and multivariate dispersion determinants) as well as in patterns of descriptor importance in Analysis of Dispersion Structure, Principal Components Analysis and Multi-group Discriminant Analysis. Members of the four groups are all apparently pseudogamous, facultative agamosperms with high pollen viability. All are apparently polyploid (mostly tetraploid with a few triploids) and self-fertile.;Taxonomic analysis, including the use of Cluster Analysis and Principal Components Analysis demonstrated that, in the study area, the series consists of six species, one of which (C. ?lumaria) is presumed to be of hybrid origin. The patterns of morphometric variation displayed by members of these species are related, in general, to a facultative apomictic mode of reproduction, and specifically to patterns of dispersal and to the postulated origin of the species within the agamic complex

An experimental quantification of kinesthetic sensation: extent of movement

Thesis (Ph.D.)--Boston University.Especially lacking for kinesthesis is knowledge concerning the nature of its psychophysical relationships. With a few exceptions there has not been developed for kinesthetic sensation the scales of sensory magnitude, as found for other sense modalities. Accordingly, an experiment was conducted for the purpose of quantifying an attribute of kinesthetic sensation, namely extent of movement. Using a similar approach to sensory quantification as that employed by S.S. Stevens, a ratio scale of sensory magnitude for this attribute 'was developed employing blind positioning movements and the psychophysical techniques of magnitude estimation and ratio production. Blind positioning movements being free of other sensory cues, provide a direct index of kinesthetic sensitivity. [TRUNCATED