135 research outputs found

    Wink: Deniable Secure Messaging

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    End-to-end encrypted (E2EE) messaging is an essential first step towards combating increasingly privacy-intrusive laws. Unfortunately, it is vulnerable to compelled key disclosure -- law-mandated, coerced, or simply by device compromise. This work introduces Wink, the first plausibly-deniable messaging system protecting message confidentiality even when users are coerced to hand over keys/passwords. Wink can surreptitiously inject hidden messages in the standard random coins (e.g., salt, IVs) used by existing E2EE protocols. It does so as part of legitimate secure cryptographic functionality deployed inside widely-available trusted execution environments (TEEs) such as TrustZone. This provides a powerful mechanism for hidden untraceable communication using virtually unchanged unsuspecting existing E2EE messaging apps, as well as strong plausible deniability. Wink has been demonstrated with multiple existing E2EE applications (including Telegram and Signal) with minimal (external) instrumentation, negligible overheads, and crucially without changing on-wire message formats

    Simplified Power Allocation for the DSL Multi-access Channel through Column-wise Diagonal Dominance

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    In the newest generation of DSL systems, crosstalk is the dominant source of performance degradation. Many crosstalk cancellation schemes have been proposed. These schemes typically employ some form of co-ordination between modems and lead to large performance gains. The use of crosstalk cancellation means that power allocation should be viewed as a multi-user problem. In this paper we investigate optimal (i.e. capacity maximizing) power allocation in DSL systems which employ co-ordination to facilitate crosstalk cancellation. By exploiting certain properties of the DSL channel, it is shown that power allocation can be simplified considerably. The result has each user waterfilling against the background noise only, explicitly ignoring the interference from other users. We show this to be near-optimal for upstream DSL when Central Office (CO) modems are co-ordinated. Compared with conventional waterfilling which is done against the background noise and interference, the performance gains are significant

    Simplified Power Allocation and TX/RX Structure for MIMO-DSL

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    In the newest generation of DSL systems crosstalk is the dominant source of performance degradation. Many crosstalk cancellation schemes have been proposed. These schemes typically employ some form of co-ordination between modems and lead to large performance gains. The use of crosstalk cancellation means that power allocation should be viewed as a multi-user problem. In this paper we investigate optimal (ie. capacity maximizing) power allocation in DSL systems which employ co-ordination to facilitate crosstalk cancellation. By exploiting certain properties of the DSL channel it is shown that power allocation can be simplified considerably. The result has each user waterfilling against the background noise only, explicitly ignoring the interference from other users. We show this to be near-optimal for upstream DSL when Central Office (CO) modems are co-ordinated. Compared with conventional waterfilling which is done against the background noise and interference, the performance gains are significant

    Carbohydrates Impact in Type 2 Diabetes in Cats

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    Diabetes is one of the most commonly diagnosed endocrine diseases in cats. Of all types of diabetes, type II is the most frequent one, 80% of the diabetic cats have type II diabetes. Even though it’s a multifactorial disease, obesity was found to be the most important risk factor in developing diabetes, obesity increases the chances of developing this disease to up to 4 times. The study was conducted on a number of 9 cats with uncomplicated diabetes with the purpose of monitoring the effects of the commercial dry food (with a high percentage of carbohydrates) and the commercial canned food (with a higher percentage of proteins and a lower percentage of carbohydrates) on the glycemic index. For this study, we considered the occasional administration of raw chicken and turkey meat because it wasn’t given for a long enough period of time. The diet is very important for diabetic cats because a lot of sick cats enter remission after a couple of months of being fed wet canned food and they no longer need the administration of insulin, but owners are instructed to carefully monitor glycaemia for the rest of the pet’s life

    Global random walk solvers for fully coupled flow and transport in saturated/unsaturated porous media

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    In this article, we present new random walk methods to solve flow and transport problems in saturated/unsaturated porous media, including coupled flow and transport processes in soils, heterogeneous systems modeled through random hydraulic conductivity and recharge fields, processes at the field and regional scales. The numerical schemes are based on global random walk algorithms (GRW) which approximate the solution by moving large numbers of computational particles on regular lattices according to specific random walk rules. To cope with the nonlinearity and the degeneracy of the Richards equation and of the coupled system, we implemented the GRW algorithms by employing linearization techniques similar to the -scheme developed in finite element/volume approaches. The resulting GRW -schemes converge with the number of iterations and provide numerical solutions that are first-order accurate in time and second-order in space. A remarkable property of the flow and transport GRW solutions is that they are practically free of numerical diffusion. The GRW solvers are validated by comparisons with mixed finite element and finite volume solvers in one- and two-dimensional benchmark problems. They include Richards’ equation fully coupled with the advection-diffusion-reaction equation and capture the transition from unsaturated to saturated flow regimes.publishedVersio

    A mixed finite element discretization scheme for a concrete carbonation model with concentration-dependent porosity

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    We discuss a prototypical reaction-diffusion-flow problem in saturated/unsaturated porous media. The special features of our problem are: the reaction produces water and therefore the flow and transport are coupled in both directions and moreover, the reaction may alter the microstructure. This means we have a variable porosity in our model. For the spatial discretization we propose a mass conservative scheme based on the mixed finite element method (MFEM). The scheme is semi-implicit in time. Error estimates are obtained for some particular cases. We apply our finite element methodology for the case of concrete carbonation – one of the most important physico-chemical processes affecting the durability of concrete

    Study of the Major Pathogens That Lead to Apple Fruit Decay During Storage

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    Different pathogenic fungi (e.g. Penicillium spp., Monilinia fructigena, Venturia inaequalis, Glomerella cingulata, Diaporthe eres etc.) can cause apple rot by producing pectic enzymes that break down apple pectin to expose the nutrients of the cells to the fungi. This study aimed to identify the pathogens that lead to the degradation of apples from five different varieties (‘Granny Smith’, ‘Topaz’, ‘Imperial Gala’, ‘Jonagold’ and ‘Golden Reinders’) and also the incidence of those pathogens under different treatment conditions. The results reveal different frequent attacks on distinct varieties ranging from 5 to over 50%. Of the pathogens that infect and occur in vegetation and deposit it can be seen that Venturia inaequalis has been identified in all varieties in most test variants. The highest frequency was recorded in the variant where during the vegetation period no treatments with fungicides against apple diseases were applied. Of the pathogens that infected and appeared during storage, isolated on the fruits, only Fusarium spp. and Penicillium spp. had a higher frequency. Applying treatments during the growing season reduced the rotting attack degree of apple fruits during storage. The best response to rot attack in the warehouse was ‘Topaz’ and ‘Jonagold’, the attack degree ranged between 0.3 and 10% on treated variants. By applying chemical treatments, the spectrum and the share of pathogens that lead to fruit degradation is different. This means that chemical treatments must be chosen depending on the nature of the pathogens and the apple variety
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