474 research outputs found

    Robust access control framework for mobile cloud computing network

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    Unified communications has enabled seamless data sharing between multiple devices running on various platforms. Traditionally, organizations use local servers to store data and employees access the data using desktops with predefined security policies. In the era of unified communications, employees exploit the advantages of smart devices and 4G wireless technology to access the data from anywhere and anytime. Security protocols such as access control designed for traditional setup are not sufficient when integrating mobile devices with organization's internal network. Within this context, we exploit the features of smart devices to enhance the security of the traditional access control technique. Dynamic attributes in smart devices such as unlock failures, application usage, location and proximity of devices can be used to determine the risk level of an end-user. In this paper, we seamlessly incorporate the dynamic attributes to the conventional access control scheme. Inclusion of dynamic attributes provides an additional layer of security to the conventional access control. We demonstrate that the efficiency of the proposed algorithm is comparable to the efficiency of the conventional schemes

    A switched reluctance motor torque ripple reduction strategy with deadbeat current control

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    This paper presents a switched reluctance motor (SRM) torque ripple reduction strategy with deadbeat current control. In this method, the SRM torque is indirectly controlled by the phase current. The deadbeat control method can predict the duty cycle of the switching signal for the next control period according to current error, and achieve an accurate current tracking. Thus, SRM torque control error can be reduced significantly. The feasibility and effectiveness of the proposed strategy have been verified in both simulation and experimental studies

    Splitting of surface defect partition functions and integrable systems

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    We study Bethe/gauge correspondence at the special locus of Coulomb moduli where the integrable system exhibits the splitting of degenerate levels. For this investigation, we consider the four-dimensional pure N=2\mathcal{N}=2 supersymmetric U(N)U(N) gauge theory, with a half-BPS surface defect constructed with the help of an orbifold or a degenerate gauge vertex. We show that the non-perturbative Dyson-Schwinger equations imply the Schr\"odinger-type and the Baxter-type differential equations satisfied by the respective surface defect partition functions. At the special locus of Coulomb moduli the surface defect partition function splits into parts. We recover the Bethe/gauge dictionary for each summand.Comment: 34 pages, 2 figures; v2. published versio

    User collusion avoidance scheme for privacy-preserving decentralized key-policy attribute-based encryption

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    Decentralized attribute-based encryption (ABE) is a variant of multi-authority based ABE whereby any attribute authority (AA) can independently join and leave the system without collaborating with the existing AAs. In this paper, we propose a user collusion avoidance scheme which preserves the user's privacy when they interact with multiple authorities to obtain decryption credentials. The proposed scheme mitigates the well-known user collusion security vulnerability found in previous schemes. We show that our scheme relies on the standard complexity assumption (decisional bilienar Deffie-Hellman assumption). This is contrast to previous schemes which relies on non-standard assumption (q-decisional Diffie-Hellman inversion)

    Analysis of the optimal operation frequency with lowest time-delay jitter for an electrically triggered field-distortion spark gap

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    This work was stimulated by the assumption that for a gas-filled spark gap closing switch operating at a high repetition frequency, there is an optimal frequency range in which the time-delay jitter reaches a minimum value. The experiments to test this assumption use an electrically triggered, field-distortion spark gap filled with the SF6/N2 gas mixture. The results show that indeed, the time-delay jitter decreases for a range of frequencies for which the filling gas can substantially restore the interelectrode insulation before increasing at a higher operation frequency. The experimental results demonstrate the correctness of the abovepresented assumption: the time-delay jitter of the field-distortion spark gap has its minimum when the unit operates in the repetition frequency range between 20 and 30 Hz. Since the recovery time depends on the gas species and the gap distance, the optimum operation frequency range should also vary depending on the spark-gap distance and the filling gas properties

    Reserve driver scheduling

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    <p>Transit agencies use reserve drivers to cover open work that arises from planned and unplanned time off, equipment breakdowns, weather, and special events. Work assignment decisions must be made sequentially without information about future job requests, a driver’s earlier assignment may not be interrupted to accommodate a new job (no pre-emption), and the scheduler may need to select a particular driver when multiple drivers can perform a job. Motivated by this instance of the interval scheduling problem, we propose a randomized algorithm that carries a performance guarantee relative to the best offline solution and simultaneously performs better than any deterministic algorithm. A key objective of this article is to develop an algorithm that performs well in both average and worst-case scenarios. For this reason, our approach includes discretionary parameters that allow the user to achieve a balance between a myopic approach (accept all jobs that can be scheduled) and a strategic approach (consider accepting only if jobs are longer than a certain threshold). We test our algorithm on data from a large transit agency and show that it performs well relative to the commonly used myopic approach. Although this article is motivated by a transit industry application, the approach we develop is applicable in a whole host of applications involving on-demand-processing of jobs. Supplementary materials are available for this article. Go to the publisher’s online edition of <i>IIE Transactions</i> for datasets, additional tables, detailed proofs, etc.</p

    Scanning Electrochemical Microscopy (SECM) of Photoinduced Electron Transfer Kinetics at Liquid/Liquid Interfaces

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    The kinetics of the photoinduced electron transfer (ET) reaction between the aqueous photosensitizer tris­(2,2-bipyridyl) ruthenium­(II) (Ru­(bipy)<sub>3</sub><sup>2+</sup>) and the organic quencher 7,7,8,8-tetracyanoquinodimethane (TCNQ) in 1,2-dichloroethane (DCE) is investigated with a scanning electrochemical microscopy (SECM) photoelectrochemical setup. In this system, an optical fiber placed in one phase is employed to illuminate the interface between two immiscible electrolyte solutions (ITIES), while an ultramicroelectrode (UME) tip in the other phase, positioned with high precision close to the end of the fiber, is used to detect the products of the photoelectrochemical process at the interface. The possible transfer of reactants and products, Ru­(bipy)<sub>3</sub><sup>2+</sup>, Ru­(bipy)<sub>3</sub><sup>3+</sup>, TCNQ, and TCNQ<sup>•–</sup>, across the interface is elucidated by extraction experiments, UV–visible spectroscopy, and SECM-double potential step chronoamperometry (SECM-DPSC) and verified to have no detectable effect on the interfacial photoinduced ET processes in this system. By applying a step function in the light flux through the optical fiber (off–on), the effects of key experimental variables on the photocurrent magnitude are determined. The resulting photochronoamperometric behavior depends on the distance between the UME and the interface, the light intensity, and the concentration of TCNQ (for a fixed concentration of Ru­(bipy)<sub>3</sub><sup>2+</sup>). A numerical model is developed and used successfully to quantitatively analyze several aspects of the photoelectrochemical process. Values of rate constants measured at different driving forces are in reasonable agreement with theoretical values calculated by the Marcus thick layer model, but the possibility of some interfacial concentration effects, which could result in a decrease of rate constant with increasing driving force, is also discussed

    A Novel Propane Monooxygenase Initiating Degradation of 1,4-Dioxane by <i>Mycobacterium dioxanotrophicus</i> PH-06

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    Monitored natural attenuation and bioremediation are cost-efficient and eco-friendly approaches to mitigating prevalent 1,4-dioxane (dioxane) plumes. Unfortunately, their field applications have been greatly undermined given our scarce knowledge of the diversity of dioxane biodegradation pathways and associated key enzymes. At present, only tetrahydrofuran monooxygenases (THF MOs) are known to initiate dioxane degradation in dioxane metabolizers. In this study, we deciphered the essential catalytic role of a novel propane MO (encoded by the <i>prmABCD</i> gene cluster) in dioxane metabolism by <i>Mycobacterium dioxanotrophicus</i> PH-06. This propane MO is phylogenetically distinct from THF MOs on the basis of the low levels of amino acid sequence identity (<40% for α subunits). Reverse transcription polymerase chain reaction (RT-PCR) analysis revealed that the <i>prmABCD</i> gene cluster is an intact transcription unit that can be induced by dioxane, THF, or propane. In addition, the biotransformation activity of this propane MO toward dioxane, THF, and propane was confirmed using heterologous expression. Detection of 2-hydroxyethoxyacetic acid (HEAA) in the expression clones proves that this propane MO catalyzes dioxane decomposition via α-hydroxylation. This first enzymological identification of the propane MO in PH-06 expands our understanding of dioxane metabolic pathways and unequivocally enables the development of molecular tools for improving the assessment of natural attenuation and bioremediation at dioxane-impacted sites

    DataSheet_1_The construction of a hypoxia-based signature identified CA12 as a risk gene affecting uveal melanoma cell malignant phenotypes and immune checkpoint expression.zip

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    Uveal melanoma (UM) is a deadly intraocular neoplasm in the adult population and harbors limited therapeutic effects from the current treatment. Here, we aimed to investigate the role of hypoxia in UM progress. We adopted the Cancer Genome Atlas data set as a training cohort and Gene Expression Omnibus data sets as validating cohorts. We first used consensus clustering to identify hypoxia-related subtypes, and the C1 subtype predicted an unfavorable prognosis and exhibited high infiltration of immunocytes and globally elevated immune checkpoint expression. Besides this, the patients with the C1 subtype were predicted to respond to the PD-1 treatment. By the least absolute shrinkage and selection operator algorithm, we constructed a hypoxia risk score based on the hypoxia genes and identified 10 genes. The risk score predicted patient survival with high performance, and the high-risk group also harbored high immunocyte infiltration and immune checkpoint expression. Furthermore, we confirmed that the risk genes were upregulated under hypoxia, and knockdown of CA12 inhibited the epithelial–mesenchymal transition process, clone formation ability, and G1/S phase transformation of the UM cells. The CD276 was also downregulated when CA12 knockdown was performed. These results validate the prognostic role of the hypoxia signature in UM and demonstrate that CA12 is a critical factor for UM cell progression as well as a target to improve immunotherapeutic effects. We believe our study contributes to the understanding of hypoxia’s roles in UM and provides a novel target that will benefit future therapeutic strategy development.</p

    El Diario de Pontevedra : periĂłdico liberal: Ano XXVII NĂşmero 7794 - 1910 maio 2

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    Meta-analysis revealed similar hospital stay in RAMPS and standard procedure. (PNG 9 kb
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