2,241 research outputs found

    Solution of the Gribov problem from gauge invariance

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    A new approach to gauge fixed Yang-Mills theory is derived using the Polyakov-Susskind projection techniques to build gauge invariant states. In our approach, in contrast to the Faddeev-Popov method, the Gribov problem does not prevent the gauge group from being factored out of the partition function. Lattice gauge theory is used to illustrate the method via a calculation of the static quark-antiquark potential generated by the gauge fields in the fundamental modular region of Coulomb gauge.Comment: 5 pages, 2 figures; contribution to the Proceedings of the 8th Conference Quark Confinement and the Hadron Spectrum, September 1-6 2008, Mainz, German

    A quality integrated spectral minutiae fingerprint recognition system

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    Many fingerprint recognition systems are based on minutiae matching. However, the recognition accuracy of minutiae-based matching algorithms is highly dependent on the fingerprint minutiae quality. Therefore, in this paper, we introduce a quality integrated spectral minutiae algorithm, in which the minutiae quality information is incorporated to enhance the performance of the spectral minutiae fingerprint recognition system. In our algorithm, two types of quality data are used. The first is the minutiae reliability, expressing the probability that a given point is indeed a minutia; the second is the minutiae location accuracy, quantifying the error on the minutiae location. We integrate these two types of quality information into the spectral minutiae representation algorithm and achieve a decrease of 1% in equal error rate in the experiment

    Hyper-peripheral regional evolution: The ā€˜long-histories\u27 of the Pilbara and Buryatia

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    In this article, we outline how evolutionary economic geography (EEG) explains peripheral economic development by comparing two peripheries over extended time periods. This comparison involves critically appraising EEGā€™s capacity to account for peripheral evolution. For geographical, historical, and political reasons, peripheries lack resources that lead to path creation and renewal. The hyper-peripheral regions of the Pilbara in north-west Australia and of Buryatia in south-east Russia provide excellent comparative case studies for understanding how peripheral regional development evolves in ways contingent upon time, state institutions, natural resource endowments, and region/firm dynamics. Our analysis shows that EEG is well equipped to deal with historical factors and capitalist economies but it struggles to reconcile these regionsā€™ resilience and ability to sustain both Indigenous and non-Indigenous socio-economies. Development in these regions over extended periods of time invites questions about whether it is appropriate to apply EEG and its constituent parts: path creation, renewal, and exhaustion; regional resilience; and institutional thinness and thickness. In addressing those questions, we show that EEG can incorporate temporal development, stretching over long periods and economic analysis. We also critique the extent to which EEG can be used to consider how state activities influence path creation and renewal, the importance of extra-regional contexts, and heterodox and Indigenous perspectives

    Spectral representation of fingerprints

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    Most fingerprint recognition systems are based on the use of a minutiae set, which is an unordered collection of minutiae locations and directions suffering from various deformations such as translation, rotation and scaling. The spectral minutiae representation introduced in this paper is a novel method to represent a minutiae set as a fixed-length feature vector, which is invariant to translation, and in which rotation and scaling become translations, so that they can be easily compensated for. These characteristics enable the combination of fingerprint recognition systems with a template protection scheme, which requires a fixed-length feature vector. This paper introduces the idea and algorithm of spectral minutiae representation. A correlation based spectral minutiae\ud matching algorithm is presented and evaluated. The scheme shows a promising result, with an equal error rate of 0.2% on manually extracted minutiae

    Antimicrobial nano-silver non-woven polyethylene terephthalate fabric via an atmospheric pressure plasma deposition process

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    An antimicrobial nano-silver non-woven polyethylene terephthalate (PET) fabric has been prepared in a three step process. The fabrics were first pretreated by depositing a layer of organosilicon thin film using an atmospheric pressure plasma system, then silver nano-particles (AgNPs) were incorporated into the fabrics by a dipping-dry process, and finally the nano-particles were covered by a second organosilicon layer of 10-50ā€‰nm, which acts as a barrier layer. Different surface characterization techniques like SEM and XPS have been implemented to study the morphology and the chemical composition of the nano-silver fabrics. Based on these techniques, a uniform immobilization of AgNPs in the PET matrix has been observed. The antimicrobial activity of the treated fabrics has also been tested using P. aeruginosa, S. aureus and C. albicans. It reveals that the thickness of the barrier layer has a strong effect on the bacterial reduction of the fabrics. The durability and stability of the AgNPs on the fabrics has also been investigated in a washing process. By doing so, it is confirmed that the barrier layer can effectively prevent the release of AgNPs and that the thickness of the barrier layer is an important parameter to control the silver ions release

    Enhanced proximity effect in zigzag-shaped Majorana Josephson junctions

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    High density superconductor-semiconductor-superconductor junctions have a small induced superconducting gap due to the quasiparticle trajectories with a large momentum parallel to the junction having a very long flight time. Because a large induced gap protects Majorana modes, these long trajectories constrain Majorana devices to a low electron density. We show that a zigzag-shaped geometry eliminates these trajectories, allowing the robust creation of Majorana states with both the induced gap EgapE_\textrm{gap} and the Majorana size Ī¾M\xi_\textrm{M} improved by more than an order of magnitude for realistic parameters. In addition to the improved robustness of Majoranas, this new zigzag geometry is insensitive to the geometric details and the device tuning.Comment: 5 pages, 4 figure

    ALPK1 mutants causing ROSAH syndrome or Spiradenoma are activated by human nucleotide sugars

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    The atypical protein kinase ALPK1 is activated by the bacterial nucleotide sugar ADP-heptose and phosphorylates TIFA to switch on a signaling pathway that combats microbial infection. In contrast, ALPK1 mutations cause two human diseases: the ALPK1[T237M] and ALPK1[Y254C] mutations underlie ROSAH syndrome (retinal dystrophy, optic nerve oedema, splenomegaly, anhidrosis, and migraine headache), while the ALPK1[V1092A] mutation accounts for 45% of spiradenoma and 30% of spiradenocarcinoma cases studied. In this study, we demonstrate that unlike wild-type (WT) ALPK1, the disease-causing ALPK1 mutants trigger the TIFA-dependent activation of an NF-ĪŗB/activator protein 1 reporter gene in the absence of ADP-heptose, which can be suppressed by either of two additional mutations in the ADP-heptose binding site that prevent the activation of WT ALPK1 by ADP-heptose. These observations are explained by our key finding that although ALPK1[T237M] and ALPK1[V1092A] are activated by bacterial ADP-heptose, they can also be activated by nucleotide sugars present in human cells (UDP-mannose, ADP-ribose, and cyclic ADP-ribose) which can be prevented by disruption of the ADP-heptose binding site. The ALPK1[V1092A] mutant was also activated by GDP-mannose, which did not activate ALPK1[T237M]. These are new examples of disease-causing mutations permitting the allosteric activation of an enzyme by endogenous molecules that the WT enzyme does not respond to. We propose that the loss of the specificity of ALPK1 for bacterial ADP-heptose underlies ROSAH syndrome and spiradenoma/spiradenocarcinoma caused by ALPK1 mutation.</p
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