Reproduction de : Thèse d'Etat : sciences appliquées : Grenoble 1 : 1967. / Titre provenant de l'écran-titre.

Frost assays carried out on winter barley (Hordeum vulgare cv Igri) showed that a single (10ml I) application of liquid seaweed extract (LSE) marginally increased the frost resistance of non-acclimated (NA) plants by 2.3% compared to NA controls and cold-acclimated (CA) plants by 2.1% compared to CA controls. Three applications of LSE increased the frost resistance of NA plants by 16% compared to NA controls and CA plants by 7.5% compared to CA controls. These observations were durable in a small scale field trial where LSE increased plant dry weights (control 0.55, single LSE, 0.611 and multiple LSE 0.621 log dry weight), but rain following LSE application reduced LSE mediated frost resistance. Glasshouse growth trials illustrated that LSE enhanced tiller production (control 2.8, one LSE 3.8 and three LSE 4.5 tillers) and dry weight gain, but where precipitation followed LSE application, up to 3 days post application, the LSE mediated effect was not sustained. Protein analysis demonstrated that cold-acclimation and LSE treatments increased the total soluble protein content of winter barley. A single application of LSE increased the soluble protein content of NA plants by 36.7% and three applications of LSE to NA plants increased protein concentration by 86.5%. There was not a significant increase in the soluble protein concentration of LSE treated CA plants. There was a significant increase in the number of high molecular weight proteins and the up-regulation of a 118kDa and a 57kDa protein when plants were treated with LSE. However precipitation following LSE application adversely affected LSE mediated protein expression. A tentative immunological identification of the up-regulated proteins suggested that the 118kDa protein is a dehydrin. There was a 2 fold decrease in plant water potential of NA plants treated with three applications of LSE compared to controls and a similar decrease in plant water potential was observed in cold-acclimated plants. The duration of LSE mediated decline in water potential lasted for 6 days, post LSE application. However there was no significant reduction in the percentage water content of cold-acclimated and LSE treated plants. Differential scanning calorimetry demonstrated that both cold-acclimated and LSE treated plants had significantly less frozen water in their crown tissue compared to non-acclimated controls. Further thermal analysis (infrared thermography and thermocouple data) showed that both cold-acclimation and LSE treatments reduced the speed of water removal from plant cells to the extracellular ice (NA 4.06, NA3LSE 13.4, CA 15.7 and CA3LSE 19.31 minutes). It is hypothesised that both CA and LSE treatments are modifying plant water status, so that water becomes more structured at the physico-chemical level, and thus alters the osmotic behaviour of cellular water. This higher level of water structuring reduces frost damage by conserving the cellular water environment and thus reducing protein denaturation and membrane damage.

This thesis examines the non-cash compensation paid to the underwriters/brokers during the flotation process and the IPO when-issued dealing market in one of the most successful and international stock exchanges around the world, the London Stock Exchange (LSE). The thesis consists of three essays that try to answer the following questions: Do IPO firms minimise their costs of going public by issuing warrants to their financial advisers? Does the when-issued dealing affect the setting of the offer price? The first essay examines the issue of warrants to brokers as part of their compensation package in non-underwritten offerings on the Alternative Investment Market of the LSE. The main finding is that IPO firms are able to make efficient decisions and choose the contract that minimises their costs. For companies that issue warrants to their brokers the total costs of going public are 22.74% (as a percentage of gross proceeds), but would have been 25.61% had they not issued them. This 2.87% reduction in costs is equivalent to 70.34% of the commission paid to the brokers by the IPO firms. The main source of this decrease in the costs is the lower underpricing the companies incur by granting warrants to their brokers. The second essay examines the use of non-cash compensation in underwritten IPOs. The findings suggest that firms that are cash constrained are more likely to issue warrants to their underwriters. In addition, underwriters appear to have the ability to time the issue of warrants because they include them as part of their compensation package when the market is doing well. Interestingly, warrant issuers are still able to minimise their costs of going public even under a very light regulatory setting underlying the use of non-cash compensation. The third essay examines the when-issued dealing in the Main Market of the LSE for an extensive period of time, 1996 to 2012. The main finding is that, in an institutional setting in which the when-issued dealing commences only after the allocation of shares and the offer price are announced, investors pay ‘rents’ to the underwriters in order to acquire IPO shares that will trade within the when-issued dealing. These ‘rents’ take the form of a higher offer price. In other words the when-issued dealing affects the setting of the offer price. For companies that have a when issued dealing the offer price is £3.4 but would have been 54% lower (£1.55) had these firms not had a when issued dealing.

Solving large-scale linear systems of equations (LSEs) is one of the most common and fundamental problems in big data. But such problems are often too expensive to solve for resource-limited users. Cloud computing has been proposed as an efficient and costeffective way of solving such tasks. Nevertheless, one critical concern in cloud computing is data privacy. Many previous works on secure outsourcing of LSEs have high computational complexity and share a common serious problem, i.e., a huge number of external memory I/O operations, which may render those outsourcing schemes impractical. We develop a practical secure outsourcing algorithm for solving large-scale LSEs, which has both low computational complexity and low memory I/O complexity and can protect clients privacy well. We implement our algorithm on a real-world cloud server and a laptop. We find that the proposed algorithm offers significant time savings for the client (up to 65%) compared to previous algorithms.

A passive radar systems opportunistic ability to exploit ambient radio signal reflections makes it ideal for covert target tracking. This strategy, referred to as passive covert radar (PCR) or passive coherent location (PCL), typically exploits FM radio or television signals from powerful local transmitters. In addition to covertness, the absence of a dedicated transmitter helps reduce costs and overall system complexity. While a variety of measurements can be used to estimate a targets position and velocity, such as time difference of arrival (TDOA) and direction of arrival (DOA), this thesis focuses on using only Doppler shift measurements to estimate a targets state. The work presented in this thesis examines the use of Doppler shift measurements from multiple receivers to solve the target tracking and association problem. A nonlinear least squares error (NLSE) estimation technique, called the Levenberg-Marquardt (L-M) algorithm, is used to determine a targets state (position, velocity) from these Doppler shift measurements. More than one target state can potentially produce identical Doppler shift profiles. In a single-receiver, single-target scenario, it is shown that three additional ghost targets caused by symmetry produce the same Doppler shift response. These ghosts may make state estimation impossible if receive antennas are not physically positioned to block out ghost targets. While the NLSE technique tends to give an accurate solution in one quadrant, three other solutions will symmetrically exist in each of the remaining three quadrants. The addition of either another receiver or another measurement (such as DOA) is needed to break this quadrant ambiguity. This thesis considers adding multiple receivers to accurately associate and track multiple targets. Two target association methods (sequential and simultaneous) are developed, and their computational requirements and accuracy are compared. A grid-aided L-M search technique is investigated in an attempt to provide a better initial target state guess to these association and tracking algorithms. The analysis and simulation results suggest it is feasible to perform multi-target association and tracking using Doppler shift as the sole measurement. Both of the proposed methods gave optimal target association and converged to reasonably accurate state estimates in most of the Monte Carlo runs.

This thesis examines the historical pattern of protest activity involving students from the University of Manchester and the London School of Economics between the academic years 1945/46 and 2010/11. Gathered through a protest event analysis of the universities’ student press, quantitative protest event data is presented that establishes a continuous pattern of protest activity at both institutions from the mid-fifties onwards. Adding to a small body of scholarship on student activism beyond the sixties epoch, the thesis challenges the assumption that student protest peaked in the late sixties, which currently dominates the student protest literature. The decade’s wave of student unrest is widely presented as exceptional and unprecedented, a golden age of student protest, casting non-sixties student generations as politically apathetic. The quantitative data refutes these claims, demonstrating an ongoing history of student protest on both campuses that sets precedent for the sixties mobilisations and undermines the idea that student apathy is pervasive on the post-sixties university campus. Between 1945/46 and 2010/11, University of Manchester students are involved in 840 protest events, while London School of Economics students participate in 505 protest events, a combined total of 1345 protest events. Using qualitative data drawn from the student press and other archival materials alongside the numeric data, the thesis argues that the British student unrest in the sixties had precedent in the fifties and early sixties, noting tactical and ideological similarities. Further, the thesis refutes the student apathy narrative using protest activity as evidence of student political participation, but also pointing to student engagement in formal and informal political activity, such as political party membership, voluntary action and campaigning for NGOs and pressure groups. Echoing studies on youth political participation, the thesis finds that students remain politically engaged across the twentieth and twenty-first century. Drawing together social movement theory with insights from the archival materials and student press, the thesis identifies factors contributing to the emergence, decline and survival of student protest activity at the University of Manchester and London School of Economics. The thesis establishes that progressive political and social values, student produced movement frames, access to resources on campus, political opportunities and campus activist networks interact to facilitate the emergence of student unrest. It also demonstrates that political factionalism and some forms of authority responses to unrest are key factors in declines in student protest activity. The thesis argues that attempts at co-option and repression by the state and the university, normally understood to prompt declines in protest, may actually provoke further activity amongst students. Applying Nella Van Dyke’s theory of ‘hotbeds of activism’ to the British context (1998), the thesis argues protest activity survives across the timeframe, because both universities have developed student activist networks and subcultures that maintain the traditions and practices of activism on campus. Activist expertise is transferred between student generations through the student unions, student societies and informal groupings, ensuring that that the campus activist networks are primed to seize opportunities for protest activity on and off campus.

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Background: Investors around the globe have debated, for more than 40 years, about whether the dividend yield has an influence on a stock’s price or not. There are different theories supporting both sides. These theories, however, often simplify the real world and therefore may not apply fully. Purpose: The purpose of this paper is to conduct empirical research on the complicated dividend policy topic and find out whether the dividend yield influences a stock’s price by testing for its effect on stock price volatility. This result finds evidence of whether investors disregard, or regard, any dividend payments and if it influences investors decisions when purchasing stock. Method: We take the top valued companies in the non-financial sector from the LSE and the Euronext between the years 2008 and 2017. We then run a Fixed Effect Model regression taking some of their reported values including their dividend yield and their stock price volatility. Conclusion: Our results indicate that the dividend yield a company pays stockholders has a positive influence on the stock price volatility, thus affecting the prices of stocks. These results counter the MM Theorem and are inconclusive with the main principles of the Bird in Hand Theorem by Gordon (1960) and Lintner (1962).

State of the art direction finding (DF) systems usually have several antennas in order to increase accuracy and robustness to certain factors. In this thesis, a three antenna DF system is built and evaluated. While more antennas give better DF performance, a three antenna system is useful for system simplicity and many of the problems in DF systems can be observed and evaluated easily. This system can be used for both azimuth and elevation direction of arrival (DOA) estimation. The system is composed of three monopole antennas, an RF front end, A/D converters and digital signal processing (DSP) units. A number of algorithms are considered, such as, three channel interferometer, correlative interferometer, LSE (least square error) based correlative interferometer and MUSIC (multiple signal classification) algorithms. Different problems in DF systems are investigated. These are gain/phase mismatch of the receiver channels, mutual coupling between antennas, multipath signals and multiple sources. The advantages and disadvantages of different algorithms are outlined.