Electronic marking and identification techniques to discourage document copying

Modern computer networks make it possible to distribute documents quickly and economically by electronic means rather than by conventional paper means. However, the widespread adoption of electronic distribution of copyrighted material is currently impeded by the ease of illicit copying and dissemination. In this paper we propose techniques that discourage illicit distribution by embedding each document with a unique codeword. Our encoding techniques are indiscernible by readers, yet enable us to identify the sanctioned recipient of a document by examination of a recovered document. We propose three coding methods, describe one in detail, and present experimental results showing that our identification techniques are highly reliable, even after documents have been photocopied

Once more about gauge invariance in \phi\to\gamma\pi0\pi0

It is argued that the realization of gauge invariance condition as a consequent of cancellation between the \phi\to\gamma f0\to\gamma\pi0\pi0 resonance contribution and a \phi\to\gamma\pi0\pi0 background one, suggested in Ref. [1], is misleading.Comment: 4 pages, one reference adde

Hydrogen bonding in C-methylated nitroanilines : the three-dimensional framework structure of 2-methyl-4-nitroaniline

Peer reviewedPublisher PD

Helping out: a national survey of volunteering and charitable giving

This report details the main findings of a national survey of volunteering and charitable giving – termed Helping Out – carried out by the National Centre for Social Research (NatCen) in partnership with the Institute for Volunteering Research (IVR) in 2006/07. The study was carried out for the Office of the Third Sector in the Cabinet Office. The main aims of the study were to examine: - how and why people give unpaid help to organisations, and what they think of their experiences; - what stops people from giving help; - the links between giving time and giving money; - how, why and how much people give money to charity; - what stops people from giving money to charity. There was also interest in estimates of the prevalence of volunteering and charitable giving. However, for a number of reasons (detailed in Chapters 2 and 10), prevalence estimates derived from this study should not be used to look at changes in these measures over time. Other study series are better suited to this purpose. In terms of volunteering, the study focused on formal help given through groups and organisations rather than informal help (given as an individual, e.g. to family and friends)

Timing of progression from Chlamydia trachomatis infection to pelvic inflammatory disease: a mathematical modelling study

PMCID: PMC3505463The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1471-2334/12/187. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Glyoxal 4-nitrophenylhydrazone : triple helices linked into a three-dimensional channel structure

Peer reviewedPublisher PD

Orange-Flesh Sweet Potato - Promising Partnerships for Assuring the Integration of Nutritional Concerns into Agricultural Research and Extension

Research Results from the Department of Policy Analysis MARD-Directorate of Economicsfood security, food policy, Mozambique, sweet potato, malnutrition, Crop Production/Industries, Food Security and Poverty, Q18,

Towards a High Energy Theory for the Higgs Phase of Gravity

Spontaneous Lorentz violation due to a time-dependent expectation value for a massless scalar has been suggested as a method for dynamically generating dark energy. A natural candidate for the scalar is a Goldstone boson arising from the spontaneous breaking of a U(1) symmetry. We investigate the low-energy effective action for such a Goldstone boson in a general class of models involving only scalars, proving that if the scalars have standard kinetic terms then at the {\em classical} level the effective action does not have the required features for spontaneous Lorentz violation to occur asymptotically $(t \to \infty)$ in an expanding FRW universe. Then we study the large $N$ limit of a renormalizable field theory with a complex scalar coupled to massive fermions. In this model an effective action for the Goldstone boson with the properties required for spontaneous Lorentz violation can be generated. Although the model has shortcomings, we feel it represents progress towards finding a high energy completion for the Higgs phase of gravity.Comment: 20 pages, 5 figures;fixed typos and added reference

Corrections to deuterium hyperfine structure due to deuteron excitations

We consider the corrections to deuterium hyperfine structure originating from the two-photon exchange between electron and deuteron, with the deuteron excitations in the intermediate states. In particular, the motion of the two intermediate nucleons as a whole is taken into account. The problem is solved in the zero-range approximation. The result is in good agreement with the experimental value of the deuterium hyperfine splitting.Comment: 7 pages, LaTe