3,754 research outputs found
The preparation of ketene dithioacetals and thiophenes from chloropyridines containing an active methylene group
The base catalysed reaction of carbon disulphide with the active methylene groups of chloropyridines 4 and 7, followed by alkylation with reagents which also contain active methylene groups, lead to ketene dithioacetals. Further reaction with base afforded highly substituted thiophenes
Opinion dynamics and decision of vote in bipolar political systems
A model of the opinion dynamics underlying the political decision is
proposed. The analysis is restricted to a bipolar scheme with a possible third
political area. The interaction among voters is local but the final decision
strongly depends on global effects such as, for example, the rating of the
governments. As in the realistic case, the individual decision making process
is determined by the most relevant personal interests and problems. The
phenomenological analysis of the national vote in Italy and Germany has been
carried out and a prediction of the next Italian vote as a function of the
government rating is presented.Comment: 8 pages, 1 figure. To be published in International Journal of Modern
Physics
Extraction, Ecology, Exploitation, and Oppression: The Political Economy of Coal in Appalachia
This thesis examines the social and ecological problems associated with mountaintop mining in central Appalachia. Theoretical insights from world system theorists and other political economists are used to trace the roots of these problems to the historical progression of different modes of extraction in the region. The restructuring of the region’s social, cultural, and ecological systems to meet the needs of core production over time has perpetuated its position as a resource extractive periphery. This occurred in three major modes: a frontier mode, an agricultural mode, and an industrial raw materials mode. The last mode has been characterized primarily by coal mining and has shifted from labor intensive forms to capital intensive forms. The role different classes of actors have played and continue to play is discussed. Finally, key processes are summarized and conclusions offered
On the distribution of the error of an interpolated value, and on the construction of tables
Before the introduction of interpolation formulae, beyond linear interpolation by proportional parts, the presentation of the numerical values of mathematical functions was much restricted, for the labour of computation and the cost of printing, to say nothing of the inconvenience of handling a bulky volume, had to be increased quite disproportionately with every increase in accuracy. A four-figure logarithm table occupies two small pages, Chambers's seven-figure table takes 150 pages, while Vega's ten figure table requires 300 pages twelve inches long
An efficiency upper bound for inverse covariance estimation
We derive an upper bound for the efficiency of estimating entries in the
inverse covariance matrix of a high dimensional distribution. We show that in
order to approximate an off-diagonal entry of the density matrix of a
-dimensional Gaussian random vector, one needs at least a number of samples
proportional to . Furthermore, we show that with samples, the
hypothesis that two given coordinates are fully correlated, when all other
coordinates are conditioned to be zero, cannot be told apart from the
hypothesis that the two are uncorrelated.Comment: 7 Page
Collaborative Privacy Policy Authoring in a Social Networking Context.
Recent years have seen a significant increase in the popularity of social networking services. These online services enable users to construct groups of contacts, referred to as friends, with which they can share digital content and communicate. This sharing is actively encouraged by the social networking services, with users privacy often seen as a secondary concern. In this paper we first propose a privacy-aware social networking service and then introduce a collaborative approach to authoring privacy policies for the service. In addressing user privacy, our approach takes into account the needs of all parties affected by the disclosure of information and digital content. © 2010 Crown
Privacy Butler: A personal privacy rights manager for online presence.
The online presence projected by a person is comprised of all the information about them available on the Internet. In online communities and social networking services, it is often possible for third-parties to modify this content by, for example, commenting on existing content or uploading new content. This has the potential to negatively impact the privacy of a presence owner (the person referred to by the on-line content) by disclosing information about them without consent. In this paper we propose a Privacy Butler, an automated service that can monitor a persons online presence and attempt to make corrections based on policies specified by the owner of the online presence. © 2010 IEEE.Accepted versio
A Field Evaluation of Selected Beach-Cleaning Techniques
A series of experiments was conducted to evaluate selected countermeasures for the cleanup of oil on remote beaches. These experiments formed part of the Baffin Island Oil Spill (BIOS) Project, which was conducted at Cape Hatt, N.W.T., between 1980 and 1983. An isolated lagoon was selected with a series of segregated bays that could be used for discrete experiments with control and countermeasure plots. Intertidal control plots were established in 1980 at an exposed site and at a relatively sheltered location. The oil on the exposed intertidal control plot was removed rapidly by natural processes so that subsequent attention was focused on low wave energy sites. Countermeasure experiments were conducted in 1981 in the intertidal zone at a relatively sheltered site and in 1982 in the intertidal and backshore zones at a very sheltered beach. At each of these two locations, control and countermeasure plots were duplicated using an aged Lagomedio crude oil and a water in aged Lagomedio emulsion. Countermeasures were selected for testing on the basis of existing experimental or practical knowledge and the applicability to remote or arctic beach environments. The selected techniques were incendiary combustion, mechanical mixing, chemical dispersion, solidifying and low-pressure flushing. ...Key words: countermeasures, dispersants, flushing, incendiary devices, mixing, natural cleaning, oil spill, shoreline, solidifying agentMots clés: mesures d’intervention, agents de dispersion, lavage à grande eau, mécanismes incendiaires, brassage, nettoyage naturel, déversement depétrole, littoral, agent solidifian
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