9,826 research outputs found

    Foreign Security Surveillance―Balancing Executive Power and the Fourth Amendment

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    Operators in Rigged Hilbert spaces: some spectral properties

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    A notion of resolvent set for an operator acting in a rigged Hilbert space \D \subset \H\subset \D^\times is proposed. This set depends on a family of intermediate locally convex spaces living between \D and \D^\times, called interspaces. Some properties of the resolvent set and of the corresponding multivalued resolvent function are derived and some examples are discussed.Comment: 29 page

    Prospects of Measuring ZZ and WZ Polarization with ATLAS

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    The measurement of angular distributions of the decay leptons in di-boson final states allows to reconstruct the spin density element rho_00 in processes where ZZ and WZ final states are produced via quark anti-quark annihilation in proton-proton collisions at the LHC. This note presents the expected sensitivity of such measurement with the ATLAS experiment, using electrons and muons as final state leptons, based on an integrated luminosity of 100 inverse femtobarns. Besides the statistical accuracy on the fraction of longitudinally polarized Z or W boson, various contributions to the systematic uncertainty, have been studied

    Non-collaborative Attackers and How and Where to Defend Flawed Security Protocols (Extended Version)

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    Security protocols are often found to be flawed after their deployment. We present an approach that aims at the neutralization or mitigation of the attacks to flawed protocols: it avoids the complete dismissal of the interested protocol and allows honest agents to continue to use it until a corrected version is released. Our approach is based on the knowledge of the network topology, which we model as a graph, and on the consequent possibility of creating an interference to an ongoing attack of a Dolev-Yao attacker, by means of non-collaboration actuated by ad-hoc benign attackers that play the role of network guardians. Such guardians, positioned in strategical points of the network, have the task of monitoring the messages in transit and discovering at runtime, through particular types of inference, whether an attack is ongoing, interrupting the run of the protocol in the positive case. We study not only how but also where we can attempt to defend flawed security protocols: we investigate the different network topologies that make security protocol defense feasible and illustrate our approach by means of concrete examples.Comment: 29 page

    Intermittent aeration in a hybrid moving bed biofilm reactor for carbon and nutrient biological removal

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    The paper presents an experimental study on a lab scale hybrid moving bed biofilm reactor with intermittent aeration. Specifically, a comparison between two different operating conditions was analyzed: continuous and intermittent aeration. Both continuous and intermittent aeration were monitored and compared in order to get the best operational conditions. The intermittent aeration campaign was sub-divided in three phases with different duration of alternation of aerobic and anoxic times and organic and nitrogen loading rates. The effciency of N-removal improved by 70% during the intermittent aeration. The best condition was observed with 40 min of aeration and 20 min of no-aeration, an organic loading rate of 2.2 kgCODm-3day-1 and a nitrogen loading rate of 0.25 kgNm-3day-1: under these operational conditions the removal effciencies for carbon and nitrogen were 93% and 90%, respectively. The derived results provide the basis for WWTP upgrade in order to meet stricter euent limits at low energy requirements

    Service Security and Privacy as a Socio-Technical Problem: Literature review, analysis methodology and challenge domains

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    Published online September 2015 accepted: 15 September 2014Published online September 2015 accepted: 15 September 2014The security and privacy of the data that users transmit, more or less deliberately, to modern services is an open problem. It is not solely limited to the actual Internet traversal, a sub-problem vastly tackled by consolidated research in security protocol design and analysis. By contrast, it entails much broader dimensions pertaining to how users approach technology and understand the risks for the data they enter. For example, users may express cautious or distracted personas depending on the service and the point in time; further, pre-established paths of practice may lead them to neglect the intrusive privacy policy offered by a service, or the outdated protections adopted by another. The approach that sees the service security and privacy problem as a socio-technical one needs consolidation. With this motivation, the article makes a threefold contribution. It reviews the existing literature on service security and privacy, especially from the socio-technical standpoint. Further, it outlines a general research methodology aimed at layering the problem appropriately, at suggesting how to position existing findings, and ultimately at indicating where a transdisciplinary task force may fit in. The article concludes with the description of the three challenge domains of services whose security and privacy we deem open socio-technical problems, not only due to their inherent facets but also to their huge number of users

    Soft Concurrent Constraint Programming

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    Soft constraints extend classical constraints to represent multiple consistency levels, and thus provide a way to express preferences, fuzziness, and uncertainty. While there are many soft constraint solving formalisms, even distributed ones, by now there seems to be no concurrent programming framework where soft constraints can be handled. In this paper we show how the classical concurrent constraint (cc) programming framework can work with soft constraints, and we also propose an extension of cc languages which can use soft constraints to prune and direct the search for a solution. We believe that this new programming paradigm, called soft cc (scc), can be also very useful in many web-related scenarios. In fact, the language level allows web agents to express their interaction and negotiation protocols, and also to post their requests in terms of preferences, and the underlying soft constraint solver can find an agreement among the agents even if their requests are incompatible.Comment: 25 pages, 4 figures, submitted to the ACM Transactions on Computational Logic (TOCL), zipped file

    Simultaneous nitrogen and organic carbon removal in aerobic granular sludge reactors operated with high dissolved oxygen concentration

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    Simultaneous nitrification and denitrification (SND) together with organic removal in granules is usually carried out without Dissolved Oxygen (DO) concentration control, at ‘‘low DO’’ (with a DO < 30–50% of the saturation value, about 3–4 mg/L) to promote anoxic conditions within the aggregates. These conditions can sometimes be in detrimental of the stability of the granules itself due to a lack of shear force. In this work, the authors achieved SND without oxygen control with big sized granules. More spe- cifically, the paper presents a experimentation focused on the analysis of two Sequencing Batch Reactors (SBRs), in bench scale, working with different aerobic sludge granules, in terms of granule size, and high DO concentration, (with concentration varying from anoxic conditions, about DO 0 mg/L, to values close to those of saturation, >7–8 mg/L, during feast and famine conditions respectively). In particular, different strategies of cultivation and several organic and nitrogen loading rate have been applied, in order to eval- uate the efficiencies in SND process without dissolved oxygen control. The results show that, even under conditions of high DO concentration, nitrogen and organic matter can be simultaneously removed, with efficiency >90%. Nevertheless, the biological conditions in the inner layer of the granule may change sig- nificantly between small and big granules, during the feast and famine periods. From point of view of granule stability, it is also interesting that with a particle size greater than 1.5 mm, after the cultivation start-up, the granules are presented stable for a long period (about 100 days) and, despite the variations of operational conditions, the granules breaking was always negligible
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