437 research outputs found

    Asymptotic correctability of Bell-diagonal qudit states and lower bounds on tolerable error probabilities in quantum cryptography

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    The concept of asymptotic correctability of Bell-diagonal quantum states is generalised to elementary quantum systems of higher dimensions. Based on these results basic properties of quantum state purification protocols are investigated which are capable of purifying tensor products of Bell-diagonal states and which are based on BB-steps of the Gottesman-Lo-type with the subsequent application of a Calderbank-Shor-Steane quantum code. Consequences for maximum tolerable error rates of quantum cryptographic protocols are discussed

    Feasibility of Producing Electricity, Hydrogen, and Chlorine via Reverse Electrodialysis

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    Reverse electrodialysis (RED) is a technology to generate electricity from two streams with different salinities. While RED systems have been conventionally used for electricity generation, recent works explored combining RED for production of valuable gases. This work investigates the feasibility of producing hydrogen and chlorine in addition to electricity in an RED stack and identifies potential levers for improvement. A simplified one-dimensional model is adopted to assess the technical and economic feasibility of the process. We notice a strong disparity in typical current densities of RED fed with seawater and river water and that in typical water (or chlor-alkali) electrolysis. This can be partly mitigated by using brine and seawater as RED feeds. Considering such an RED system, we estimate a hydrogen production of 1.37 mol/(m2h) and an electrical power density of 1.19 W/m2. Although this exceeds previously reported hydrogen production rates in combination with RED, the levelized costs of products are 1-2 orders of magnitude higher than the current market prices at the current state. The levelized costs of products are very sensitive to the membrane price and performance. Hence, going forward, manufacturing thinner and highly selective membranes is required to make the system competitive against the consolidated technologies

    Instrumentation System for Thermal analysis of Electro-Explosive Devices.

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    A constant current pulser, with adjustable pulse width and current, is designed to evaluate thermal characteristics of electro-explosive devices (EED). The thermal response in voltage/time profile is digitised and recorded on a PC. A software for the analysis of this data has been developed. It computes the heat loss coefficient (Lambda), thermal capacity (Co) and thermal time constant (of the system. These parameters are used for the prediction of the performance EEDs during development stage and also in quality control. A computerised system developed for this purpose is also described in detail

    A different approach to soil analysis: Indicative studies

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    Soil analysis is a tool that has been employed with the primary goal of providing recommendations for soil rectification, crop productivity and for soil health management. Time tested methods like ammonium acetate extraction and diethylene triamine penta acetic acid (DTPA) are commonly used for analysis of bioavailable nutrients. However, there are some limitations to these methods as both extraction fluids are buffered to neutral or near-neutral pH. Hence extracted nutrients represent a “potential or ideal-case” fertility status of soil instead of an “actual” field status. In the ‘Regular methods’, we are overlooking the role of pH, the master variable, in determining the availability of nutrients. Hence, in ‘Modified methods’, the extraction fluid is buffered to actual soil pH. Results obtained with over 150 random samples representing a range of pH, have indicated a difference in values between regular and modified extraction methods. The modified methods (MM) of ammonium acetate and DTPA extraction adjusted to soil pH were found to be better than regular method (RM) for estimation of calcium, magnesium with ammonium acetate and iron and manganese with DTPA in alkaline soils above pH 8.0. For a complete picture of soil health, productivity and fertility, microbiological and enzymatic analysis of soils were included in the present study. Soil solution equivalent medium (SSE) was found to be the appropriate culture medium for microbial counts. A linear relationship was found between urease activity and available nitrogen of soil

    Spectral properties of entanglement witnesses

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    Entanglement witnesses are observables which when measured, detect entanglement in a measured composed system. It is shown what kind of relations between eigenvectors of an observable should be fulfilled, to allow an observable to be an entanglement witness. Some restrictions on the signature of entaglement witnesses, based on an algebraic-geometrical theorem will be given. The set of entanglement witnesses is linearly isomorphic to the set of maps between matrix algebras which are positive, but not completely positive. A translation of the results to the language of positive maps is also given. The properties of entanglement witnesses and positive maps express as special cases of general theorems for kk-Schmidt witnesses and kk-positive maps. The results are therefore presented in a general framework.Comment: published version, some proofs are more detailed, mistakes remove

    Trends in Metal Oxide Stability for Nanorods, Nanotubes, and Surfaces

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    The formation energies of nanostructures play an important role in determining their properties, including the catalytic activity. For the case of 15 different rutile and 8 different perovskite metal oxides, we find that the density functional theory (DFT) calculated formation energies of (2,2) nanorods, (3,3) nanotubes, and the (110) and (100) surfaces may be described semi-quantitatively by the fraction of metal--oxygen bonds broken and the bonding band centers in the bulk metal oxide

    Manipulating sudden death of entanglement of two-qubit X-states in thermal reservoirs

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    Manipulation of sudden death of entanglement (ESD) of two qubits interacting with statistically uncorrelated thermal reservoirs is investigated. It is shown that for initially prepared X-states of the two qubits a simple (necessary and sufficient) criterion for ESD can be derived with the help of the Peres-Horodecki criterion. This criterion implies that, in contrast to the zero-temperature case, at finite temperature of at least one of the reservoirs all initially prepared two-qubit X-states exhibit ESD. General conditions are derived under which ESD can be hastened, delayed, or averted.Comment: 8 pages, 3 figures. Title and abstract are slightly modifie

    Spatially organizing future genders: an artistic intervention in the creation of a hir-toilet

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    Toilets, a neglected facility in the study of human relations at work and beyond, have become increasingly important in discussions about future experiences of gender diversity. To further investigate the spatial production of gender and its potential expressions, we transformed a unisex single-occupancy toilet at Uppsala University into an all-gender or ‘hir-toilet’.1 With the aim to disrupt and expose the dominant spatial organization of the two binary genders, we inaugurated the hir-toilet with the help of a performance artist. We describe and analyse internal and external responses thereto, using Lefebvre’s work on dialectics and space. Focusing on how space is variously lived, conceived and perceived, our analysis questions the very rationale of gender categorizations. The results contribute to a renewed critique of binary thinking in the organization of workplaces by extending our understanding of how space and human relations mutually constitute each other

    Beta1-Adrenoceptor Polymorphism Predicts Flecainide Action in Patients with Atrial Fibrillation

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    BACKGROUND: Antiarrhythmic action of flecainide is based on sodium channel blockade. Beta(1)-adrenoceptor (beta(1)AR) activation induces sodium channel inhibition, too. The aim of the present study was to evaluate the impact of different beta(1)AR genotypes on antiarrhythmic action of flecainide in patients with structural heart disease and atrial fibrillation. METHODOLOGY/PRINCIPAL FINDINGS: In 145 subjects, 87 with atrial fibrillation, genotyping was performed to identify the individual beta(1)AR Arg389Gly and Ser49Gly polymorphism. Resting heart rate during atrial fibrillation and success of flecainide-induced cardioversion were correlated with beta(1)AR genotype. The overall cardioversion rate with flecainide was 39%. The Arg389Arg genotype was associated with the highest cardioversion rate (55.5%; OR 3.30; 95% CI; 1.34-8.13; p = 0.003) compared to patients with Arg389Gly (29.5%; OR 0.44; 95% CI; 0.18-1.06; p = 0.066) and Gly389Gly (14%; OR 0.24; 95% CI 0.03-2.07; p = 0.17) variants. The single Ser49Gly polymorphism did not influence the conversion rate. In combination, patients with Arg389Gly-Ser49Gly genotype displayed the lowest conversion rate with 20.8% (OR 0.31; 95% CI; 0.10-0.93; p = 0.03). In patients with Arg389Arg variants the heart rate during atrial fibrillation was significantly higher (110+/-2.7 bpm; p = 0.03 vs. other variants) compared to Arg389Gly (104.8+/-2.4 bpm) and Gly389Gly (96.9+/-5.8 bpm) carriers. The Arg389Gly-Ser49Gly genotype was more common in patients with atrial fibrillation compared to patients without atrial fibrillation (27.6% vs. 5.2%; HR 6.98; 95% CI; 1.99-24.46; p<0.001). CONCLUSIONS: The beta(1)AR Arg389Arg genotype is associated with increased flecainide potency and higher heart rate during atrial fibrillation. The Arg389Gly-Ser49Gly genotype might be of predictive value for atrial fibrillation

    A novel physics informed deep learning method for simulation-based modelling

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    In this paper, we present a brief review of the state of the art physics informed deep learning methodology and examine its applicability, limits, advantages, and disadvantages via several applications. The main advantage of this method is that it can predict the solution of the partial differential equations by using only boundary and initial conditions without the need for any training data or pre-process phase. Using physics informed neural network algorithms, it is possible to solve partial differential equations in many different problems encountered in engineering studies with a low cost and time instead of traditional numerical methodologies. A direct comparison between the initial results of the current model, analytical solutions, and computational fluid dynamics methods shows very good agreement. The proposed methodology provides a crucial basis for solution of more advance partial differential equation systems and offers a new analysis and mathematical modelling tool for aerospace application
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