Towards eradication of SPAM: A study on intelligent adaptive SPAM filters

As the massive increase of electronic mail (email) usage continues, SPAM (unsolicited bulk email), has continued to grow because it is a very inexpensive method of advertising. These unwanted emails can cause a serious problem by filling up the email inbox and thereby leaving no space for legitimate emails to pass through. Currently the only defense against SPAM is the use of SPAM filters. A novel SPAM filter GetEmail5 along with the design rationale, is described in this thesis. To test the efficacy of GetEmail5 SPAM filter, an experimental setup was created and a commercial bulk email program was used to send SPAM and non-SPAM emails to test the new SPAM filter. GetEmail5's efficiency and ability to detect SPAM was compared against two highly ranked commercial SPAM filters on different sets of emails, these included all SPAM, non-SPAM, and mixed emails, also text and HTML emails. The results showed the superiority of GetEmail5 compared to the two commercial SPAM filters in detecting SPAM emails and reducing the user's involvement in categorizing the incoming emails. This thesis demonstrates the design rationale for GetEmail5 and also its greater effectiveness in comparison with the commercial SPAM filters tested

The Economic Impact of Social Ties: Evidence from German Reunification

We use the fall of the Berlin Wall in 1989 to show that personal relationships which individuals maintain for non-economic reasons can be an important determinant of regional economic growth. We show that West German households who have social ties to East Germany in 1989 experience a persistent rise in their personal incomes after the fall of the Berlin Wall. Moreover, the presence of these households significantly affects economic performance at the regional level: it increases the returns to entrepreneurial activity, the share of households who become entrepreneurs, and the likelihood that firms based within a given West German region invest in East Germany. As a result, West German regions which (for idiosyncratic reasons) have a high concentration of households with social ties to the East exhibit substantially higher growth in income per capita in the early 1990s. A one standard deviation rise in the share of households with social ties to East Germany in 1989 is associated with a 4.6 percentage point rise in income per capita over six years. We interpret our findings as evidence of a causal link between social ties and regional economic development.economic development, German reuni cation, networks, social ties

Estudios de sensibilidad para el Cherenkov Telescope Array

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, Departamento de Física Atómica, Molecular y Nuclear, leída el 28-09-2015Since the creation of the first telescope in the 17th century, every major discovery in astrophysics has been the direct consequence of the development of novel observation techniques, opening new windows in the electromagnetic spectrum. After Karl Jansky discovered serendipitously the first radio source in 1933, Grote Reber built the first parabolic radio telescope in his backyard, planting the seed of a whole new field in astronomy. Similarly, new technologies in the 1950s allowed the establishment of other fields, such as the infrared, ultraviolet or the X-rays. The highest energy end of the electromagnetic spectrum, the gamma-ray range, represents the last unexplored window for astronomers and should reveal the most extreme phenomena that take place in the Universe. Given the technical complexity of gamma-ray detection and the extremely relative low fluxes, gamma-ray astronomy has undergone a slower development compared to other wavelengths. Nowadays, the great success of consecutive space missions together with the development and refinement of new detection techniques from the ground, has allowed outstanding scientific results and has brought gamma-ray astronomy to a worthy level in par with other astronomy fields. This work is devoted to the study and improvement of the future Cherenkov Telescope Array (CTA), the next generation of ground based gamma-ray detectors, designed to observe photons with the highest energies ever observed from cosmic sources. These results on the sensitivity studies performed for the CTA collaboration evaluate the observatory performance through the analysis of large-scale Monte Carlo (MC) simulations, along with an estimation of its future potential on specific physics cases. Together with the testing and development of the analysis tools employed, these results are critical to understand CTA's future capabilities, the efficiency of different telescope placement approaches and the effect on performance of the construction site, related to parameters such as the altitude or the geomagnetic field. The Northern Hemisphere proposed construction sites were analyzed and evaluated, providing an accurate estimation of their capabilities to host the observatory. As for the CTA layout candidates, an unbiased comparison of the different arrays proposed by the collaboration was performed, using Fermi-LAT catalogs to forecast the performance of each array over specific scientific cases. In addition, the application of machine learning algorithms on gamma-ray astronomy was studied, comparing alternative methods for energy reconstruction and background suppression and introducing new applications to these algorithms, such as the determination of gamma-ray source types through the training of their spectral features. The analysis presented here of both CTA-N and CTA-S candidates represents the most comprehensive study of CTA capabilities performed by the collaboration to date. Experience gained with the improvement of this software will guide the future \gls{cta} analysis pipelines by comparing the attained sensitivity by alternative analysis chains. From these results, both CTA-N and CTA-S candidates "2N" and "2Q" fulfill the sensitivity, angular and energy resolution, effective area and off-axis performance requirements. MC simulations provide an useful test-bench for the different designs within the CTA project, and these results demonstrate their correct implementation would attain the desired performance and potential scientific output.Depto. de Estructura de la Materia, Física Térmica y ElectrónicaFac. de Ciencias FísicasTRUEunpu

The Social Cost of Near-Rational Investment

We show that the stock market may fail to aggregate information even if it appears to be efficient; the resulting collapse in the dissemination of information may drastically reduce welfare. We solve a macroeconomic model in which information about fundamentals is dispersed and households make small, correlated errors around their optimal investment policies. As information aggregates in the market, these errors amplify and crowd out the information content of stock prices. When stock prices reflect less information, the perceived and the actual volatility of stock returns rise. This increase in financial risk makes holding stocks unattractive, distorts the long-run level of capital accumulation, and causes costly ( first-order) distortions in the long-run level of consumption

The Quality of Work Life: An Empirical Study

Merged with duplicate record (10026.1/2769) on 03.01.2017 by CS (TIS)This research examines the quality of work life in a selection of pharmaceutical companies in Egypt. It aims to test the relationships between the employees' perceptions of their quality of work life and; their perceptions of the degree of participation in decisionmaking available to them, their perceptions of their level of job satisfaction, their perceptions of their level of affective, continuance, and normative commitment, and the ownership form of the company. It uses a sample of 1270 employees in three different ownership forms; public, private, and multinational pharmaceutical companies in Egypt. The total sample size is proportionately distributed (i. e. the actual 'sample size has been distributed between the three ownership forms based on the percentage of employees in each ownership form to the total size of the population) among' , the three, forms Of ownership (public companies 889, private companies = 165, and multinational companies = 216 employee). The number of employees surveyed in each company has also been proportionately distributed. The perceptions of the targeted employees are surveyed using a questionnaire that contains 81 items. The collected data are analysed using the Statistical Package for Social Sciences (SPSS) programme. The findings of the study indicate that there is a significant positive relationship between the employees' perceptions of their quality of work life and; their perceptions of the degree of participation in decision-making available to them, and their perceptions of their level of job satisfaction. A significant positive and partial relationship is found between the employees' perceptions of their quality of work life and their perceptions of III their level of affective, continuance, and normative commitment, as it is expected, by the researcher, that the employees' perceptions of their quality of work life may positively affect their perceptions of their level of affective, continuance, and normative commitment through affecting their perceptions of their level of job satisfaction. A significant relationship is found between the employees' perceptions of their quality of work life and the ownership form of the company. The results also indicate that employees perceive their quality of work life to be greater or better in the multinational pharmaceutical companies than are the employees' perceptions of their quality of work life in both the private and public pharmaceutical companies in Egypt. Furthermore, the results indicate that the employees' perceptions of their quality of work life in the private phan-naceutical companies are better than the employees' perceptions of their quality of work life in the public phan-naceutical companies in Egypt. A set of quality of work life criteria that seems important to employees in the pharmaceutical companies in Egypt, and which might therefore be productively addressed by employers/organisations has been identified. In addition, some implications for HR practices in Egypt have been raised and discussed. Finally, a set of models that could clarify the interactive relationship between the variables that have been investigated in this research in the Egyptian context has been developed. It is suggested that the set of quality of work life criteria as well as the models might fon-n the basis for future researches of this type

Pressure gradients in molecular dynamics simulations of nano-confined fluid flow

Ein detailliertes Verständnis des Verhaltens von Schmierstoffen in engen Spalten ist für eine Reihe von medizinischen und industriellen Anwendungen entscheidend. Die hydrodynamischen Grundgleichungen bieten genaue Lösungen, sofern die kontaktierenden Körper ausreichend weit voneinander entfernt sind. Unter extremen Belastungsbedingungen werden jedoch Abweichungen von den Navier-Stokes-Fourier-Gleichungen beobachtet. Dies liegt hauptsächlich an der Bedeutung atomare Effekte, die eine homogenisierte Betrachtung im Rahmen von Kontinuumstheorien nicht mehr erlauben, sodass die Flüssigkeit als Ansammlung diskreter Partikel behandelt werden muss. Der multiskalige Charakter des Problems wird im Bereich der Grenzreibung umso deutlicher. In diesem Regime wird das Schmiermittel durch Druckgradienten angetrieben, die sich aus der Variation der Spalthöhe zwischen den kontaktierenden Körpern ergeben. In der atomistischen Modellierung werden üblicherweise Nichtgleichgewichts-Molekulardynamik (NEMD) Simulationen periodischer, repräsentativer Volumenelemente (RVE) verwendet, bei denen der Schmierfilm von flachen Wänden eingeschlossen wird. Aufgrund der Periodizität stellt das Einstellen von Druckgradienten in solchen Modellen eine Hürde dar. In dieser Arbeit wurde die ``Pump\u27\u27-Methode entwickelt, um Druckgradienten in periodischen Systemen einzuführen, indem eine lokale Störung aufgebracht wird, die unter Einhaltung der Impulserhaltung einen druckgetriebenen Fluss des Schmiermittels induziert. Dabei kann sowohl der Massenfluss als auch der Druckgradient, durch Festlegen atomarer Kräfte, als unabhängige Variable gewählt werden. Die Methode wurde für kompressible Fluide mit unterschiedlichen Benetzungseigenschaften und in Verbindung mit verschiedenen Thermostat-Strategien getestet. Dabei werden die thermodynamischen Feldgrößen Druck, Temperatur und Geschwindigkeit des Schmierstoffs in Spalthöhen bis zu drei Moleküldurchmessern gemessen. Die Pump-Methode kann auf Kanäle beliebiger Geometrie angewendet werden, was die Anwendung zur Untersuchung hydrodynamischer Kavitation ermöglicht -- ein Phänomen, welches in der Natur allgegenwärtig ist, jedoch auf molekularer Ebene bisher kaum untersucht wurde. Dazu wurde die Kanalgeometrie anhand einer Sensitivitätsanalyse optimiert. Anschließend wurde die Lebensdauer der Kavitationsblasen, sowie deren Wachstum und Zusammenbruch mit den theoretischen, hydrodynamischen Vorhersagen verglichen. Im Rahmen eines Multiskalenansatzes für Schmierungsprobleme kann die Pump-Methode zur Einstellung der Randbedingungen eines molekularen Systems im Einklang mit Kontinuumssimulationen verwendet werden

VOLUNTARY DISCLOSURE PRACTICES IN EMERGING CAPITAL MARKETS: THE CASE OF EGYPT

Corporate governance is a crucial issue that is being addressed widely by regulators, and capital market participants around the world. Disclosure is identified as one of the challenges facing the implementation of corporate governance especially in developing countries. The current study aims to contribute to corporate governance and disclosure literature by oroviding empirical evidence of the relationship between corporate governance, ownership structure and the voluntary disclosure in an emerging capital market, namely Egypt. The study assesses the extent of total voluntary disclosure and its categories in the annual reports of the most active non financial companies m the Cairo and Alexandria Stock Exchange over four years that witnessed a remarkable initiatives to enhance transparency and corporate governance. It employs a wider theoretical framework based mainly on the political ach and benefits from institutional theory. Using a sample of 182 annual reports of the most active Egyptian listed companies, the findings indicate that while the extent of voluntary disclosure is low, there was a gradual increase in the extent of total voluntary disclosure and its categories over the examined period. However, there is no significant difference between the voluntary disclosure over the four years. This suggests that companies manage their voluntary disclosure policy which is not a random practice but subject to certain influences. The reRression results indicate the board characteristics; board size and board composition; do affect the extent of voluntary disclosure. Interestingly, the findings indicate that the existence of family members on the board has a positive association with the extent of total voluntary disclosure. This suggests that family led companies may have a litigation and reputation cost concern.EThOS - Electronic Theses Online ServiceGBUnited Kingdo