Hierarchical Trustworthy Authentication for Pervasive Computing

This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder. -- -- Copyright IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE

Modelling and Analysis of TCP Performance in Wireless Multihop Networks

Researchers have used extensive simulation and experimental studies to understand TCP performance in wireless multihop networks. In contrast, the objective of this paper is to theoretically analyze TCP performance in this environment. By examining the case of running one TCP session over a string topology, a system model for analyzing TCP performance in multihop wireless networks is proposed, which considers packet buffering, contention of nodes for access to the wireless channel, and spatial reuse of the wireless channel. Markov chain modelling is applied to analyze this system model. Analytical results show that when the number of hops that the TCP session crosses is fixed, the TCP throughput is independent of the TCP congestion window size. When the number of hops increases from one, the TCP throughput decreases first, and then stabilizes when the number of hops becomes large. The analysis is validated by comparing the numerical and simulation result

Threat Analysis of Software Agents in Online Banking and Payments

Software agents are the delegated subcontractors essential to connect the end-user to the bank and payment providers in a distributed service offering. This paper evaluates the key role that the different software agent types play to facilitate collaboration between clients and banks to perform online transactions. It highlights the threats and imminent risks that these software agents introduce in the chain as well as how these threats affect the trust relationship between principals. The discussed threats and resulting risks suggest vulnerabilities in the current software agent model which are beyond the bank and end users control. Both principals, the client and the service provider, are open to potential legal, security, quality of service, confidentiality and privacy compromises which influence the overarching trust relationship. There is resounding literature to illustrate advances that have been made to address the exposed challenges. However, a gap of misfortune remains where the software agent can act on its own accord exposing the contracting principals to internal and externally engineered threats thus tainting the trust relationship between these parties

A purchase protocol with multichannel authentication

While online shopping are becoming more accepted by people in modern life, cardholders are more concerned about card fraud and the lack of cardholder authentication in the current online credit card payment. This paper proposes a purchase protocol with live cardholder authentication for online transactions which combines telephone banking and online banking together. The order information and payment information are sent though the Internet and encrypted by asymmetric key encryption. The cardholder is authenticated by the card issuing bank ringing back at the customer’s phone number and the cardholder inputting the secure PIN and the amount to pay. The multichannel authentication makes the cardholder feel secure and card fraud difficult. Furthermore, the protocol does not require the cardholder to obtain public key certificates or install additional software for online transactions

Influence of commercial formulation on leaching of four pesticides through soil

Studies with small soil columns (2 cm i.d. x 5.4 cm depth) compared leaching of four pesticides added either as technical material or as commercial formulations. Pesticides were selected to give a gradient of solubility in water between 7 and 93 mg L-1, comprising azoxystrobin (emulsifiable concentrate, EC, and suspension concentrate, SC), cyproconazole (SC), propyzamide (SC) and triadimenol (EC). Columns of sandy loam soil were leached with 6 pore volumes of 0.01M CaCl2 either 1 or 7 days after treatment. Separate experiments evaluated leaching of triadimenol to full breakthrough following addition of 18 pore volumes of 0.01M CaCl2. The mass of pesticide leached from columns treated with commercial formulation was significantly larger than that from columns treated with technical material for all compounds studied and for both leaching intervals (two-sided t-tests, p<0.001). This difference was conserved when triadimenol was leached to full breakthrough with 79 ± 1.2 and 61 ± 3.1% of applied triadimenol leached from columns treated with formulated and technical material, respectively. There were highly significant effects of formulation for all pesticides (two-way ANOVA, p<0.001), whereas leaching interval was only significant for azoxystrobin EC formulation and cyproconazole (p <0.001 and 0.021, respectively) with greater leaching when irrigation commenced 1 day after treatment. Leaching of azoxystrobin increased in the order technical material (6.0% of applied pesticide) < SC formulation (8.5-9.1% of applied) < EC formulation (15.8-21.0% of applied). The relative difference between leaching of formulated and technical pesticide increased with pesticide solubility in water, increasing from a factor of 1.4 for the SC formulation of azoystrobin to 4.3 for the SC formulation of triadimenol. Experimental systems differ markedly from field conditions (small columns with intense irrigation). Nevertheless, results indicate the need to consider further the influence of co-formulants in pesticide formulations on behaviour of the active ingredient in soil

Introducing the 2-DROPS model for two-dimensional simulation of crop roots and pesticide within the soil-root zone

Mathematical models of pesticide fate and behaviour in soils have been developed over the last 30 years. Most models simulate fate of pesticides in a 1-dimensional system successfully, supporting a range of applications where the prediction target is either bulk residues in soil or receiving compartments outside of the soil zone. Nevertheless, it has been argued that the 1-dimensional approach is limiting the application of knowledge on pesticide fate under specific pesticide placement strategies, such as seed, furrow and band applications to control pests and weeds. We report a new model (2-DROPS; 2-Dimensional ROots and Pesticide Simulation) parameterised for maize and we present simulations investigating the impact of pesticide properties (thiamethoxam, chlorpyrifos, clothianidin and tefluthrin), pesticide placement strategies (seed treatment, furrow, band and broadcast applications), and soil properties (two silty clay loam and two loam top soils with either silty clay loam, silt loam, sandy loam or unconsolidated bedrock in the lower horizons) on microscale pesticide distribution in the soil profile. 2-DROPS is to our knowledge the first model that simulates temporally- and spatially-explicit water and pesticide transport in the soil profile under the influence of explicit and stochastic development of root segments. This allows the model to describe microscale movement of pesticide in relation to root segments, and constitutes an important addition relative to existing models. The example runs demonstrate that the pesticide moves locally towards root segments due to water extraction for plant transpiration, that the water holding capacity of the top soil determines pesticide transport towards the soil surface in response to soil evaporation, and that the soil type influences the pesticide distribution zone in all directions. 2-DROPS offers more detailed information on microscale root and pesticide appearance compared to existing models and provides the possibility to investigate strategies targeting control of pests at the root/soil interface

Cottage industry, migration, and marriage in nineteenth-century England

The original article can be found at: http://www3.interscience.wiley.com Copyright Economic History Society. DOI: 10.1111/j.1468-0289.2007.00413.xPeer reviewe

Associations between perceived neighbourhood problems and quality of life in older adults with and without osteoarthritis:Results from the Hertfordshire cohort study

This study examined whether the association of quality of life (QoL) with perceived neighbourhood problems is stronger in older adults with osteoarthritis (OA) than in those without OA. Of all 294 participants, 23.8% had OA. More perceived neighbourhood problems were associated with a stronger decrease in QoL over time in participants with OA (B=-0.018; p=0.02) than in those without OA (B=-0.004; p=0.39). Physical activity did not mediate this relationship. Older adults with OA may be less able to deal with more challenging environments