2,130 research outputs found

    Genomic analysis of 48 paenibacillus larvae bacteriophages

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    Indexación: Scopus.Funding: Research at UNLV was funded by National Institute of General Medical Sciences grant GM103440 (NV INBRE), the UNLV School of Life Sciences, and the UNLV College of Sciences. E.C.-N. was funded by CONICYT-FONDECYT de iniciación en la investigación 11160905. Research at BYU was funded by the BYU Microbiology & Molecular Biology Department, and private donations through LDS Philanthropies.The antibiotic-resistant bacterium Paenibacillus larvae is the causative agent of American foulbrood (AFB), currently the most destructive bacterial disease in honeybees. Phages that infect P. larvae were isolated as early as the 1950s, but it is only in recent years that P. larvae phage genomes have been sequenced and annotated. In this study we analyze the genomes of all 48 currently sequenced P. larvae phage genomes and classify them into four clusters and a singleton. The majority of P. larvae phage genomes are in the 38–45 kbp range and use the cohesive ends (cos) DNA-packaging strategy, while a minority have genomes in the 50–55 kbp range that use the direct terminal repeat (DTR) DNA-packaging strategy. The DTR phages form a distinct cluster, while the cos phages form three clusters and a singleton. Putative functions were identified for about half of all phage proteins. Structural and assembly proteins are located at the front of the genome and tend to be conserved within clusters, whereas regulatory and replication proteins are located in the middle and rear of the genome and are not conserved, even within clusters. All P. larvae phage genomes contain a conserved N-acetylmuramoyl-L-alanine amidase that serves as an endolysin. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.https://www.mdpi.com/1999-4915/10/7/37

    An Adaptive Secondary Mirror demonstrator: Construction and Preliminary Evaluation

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    Adaptive optics combines technologies that enable the correction of the wavefront distortion caused by the earth‘s atmospheric turbulence in real time. Adaptive secondary mirror (ASM) systems have been proposed and are now being developed. ASMs have advantages over conventional AO systems in terms of throughput, polarisation and IR emissivity. Previously, we reported the design of an ASM demonstrator along with its predicted performance. This paper reports the construction techniques and the results from the preliminary static and dynamic testing of such a demonstrator. In particular assembly methods that preserve the optical quality of the mirror are presented along with experimentally measured mirror influence functions and closed loop tip/tilt performance

    Severe Spotted Fever Group Rickettsiosis, Australia

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    We report 3 cases of spotted fever group rickettsial infection (presumed Queensland tick typhus) in residents of northern Queensland, Australia, who had unusually severe clinical manifestations. Complications included renal failure, purpura fulminans, and severe pneumonia. Clinical illness caused by Rickettsia australis may not be as benign as previously described

    Articular contact in a three-dimensional model of the knee

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    This study is aimed at the analysis of articular contact in a three-dimensional mathematical model of the human knee-joint. In particular the effect of articular contact on the passive motion characteristics is assessed in relation to experimentally obtained joint kinematics. Two basically different mathematical contact descriptions were compared for this purpose. One description was for rigid contact and one for deformable contact. The description of deformable contact is based on a simplified theory for contact of a thin elastic layer on a rigid foundation. The articular cartilage was described either as a linear elastic material or as a non-linear elastic material. The contact descriptions were introduced in a mathematical model of the knee. The locations of the ligament insertions and the geometry of the articular surfaces were obtained from a joint specimen of which experimentally determined kinematic data were available, and were used as input for the model. The ligaments were described by non-linear elastic line elements. The mechanical properties of the ligaments and the articular cartilage were derived from literature data. Parametric model evaluations showed that, relative to rigid articular contact, the incorporation of deformable contact did not alter the motion characteristics in a qualitative sense, and that the quantitative changes were small. Variation of the elasticity of the elastic layer revealed that decreasing the surface stiffness caused the ligaments to relax and, as a consequence, increased the joint laxity, particularly for axial rotation. The difference between the linear and the non-linear deformable contact in the knee model was very small for moderate loading conditions. The motion characteristics simulated with the knee model compared very well with the experiments. It is concluded that for simulation of the passive motion characteristics of the knee, the simplified description for contact of a thin linear elastic layer on a rigid foundation is a valid approach when aiming at the study of the motion characteristics for moderate loading conditions. With deformable contact in the knee model, geometric conformity between the surfaces can be modelled as opposed to rigid contact which assumed only point contact

    Magnetic-interference patterns in Josephson junctions with d+is symmetry

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    The magnetic interference pattern and the spontaneous flux in unconventional Josephson junctions of superconductors with d+is symmetry are calculated for different reduced junction lengths and the relative factor of the d and s wave components. This is a time reversal broken symmetry state. We study the stability of the fractional vortex and antivortex which are spontaneously formed and examine their evolution as we change the length and the relative factor of d and s wave components. The asymmetry in the field modulated diffraction pattern exists for lengths as long as L=10\lambda_J.Comment: 8 pages, 6 eps files, submitted to PR

    Far-Field Species Distribution Measurements on the BHT-600 Hall Thruster Cluster

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76148/1/AIAA-2007-5304-543.pd

    Plasma Turbulence in the Local Bubble

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    Turbulence in the Local Bubble could play an important role in the thermodynamics of the gas that is there. The best astronomical technique for measuring turbulence in astrophysical plasmas is radio scintillation. Measurements of the level of scattering to the nearby pulsar B0950+08 by Philips and Clegg in 1992 showed a markedly lower value for the line-of-sight averaged turbulent intensity parameter thanisobservedforotherpulsars,consistentwithradiowavepropagationthroughahighlyrarefiedplasma.Inthispaper,wediscusstheobservationalprogressthathasbeenmadesincethattime.Atpresent,therearefourpulsars(B0950+08,B1133+16,J04374715,andB0809+74)whoselinesofsightseemtoliemainlywithinthelocalbubble.Themeandensitiesandlineofsightcomponentsoftheinterstellarmagneticfieldalongtheselinesofsightaresmallerthannominalvaluesforpulsars,butnotbyasmuchexpected.Threeofthefourpulsarsalsohavemeasurementsofinterstellarscintillation.Thevalueoftheparameter than is observed for other pulsars, consistent with radio wave propagation through a highly rarefied plasma. In this paper, we discuss the observational progress that has been made since that time. At present, there are four pulsars (B0950+08, B1133+16, J0437-4715, and B0809+74) whose lines of sight seem to lie mainly within the local bubble. The mean densities and line of sight components of the interstellar magnetic field along these lines of sight are smaller than nominal values for pulsars, but not by as much expected. Three of the four pulsars also have measurements of interstellar scintillation. The value of the parameter is smaller than normal for two of them, but is completely nominal for the third. This inconclusive status of affairs could be improved by measurements and analysis of ``arcs'' in ``secondary spectra'' of pulsars.Comment: Submitted to Space Science Reviews as contribution to Proceedings of ISSI (International Space Science Institute) workshop "From the Heliosphere to the Local Bubble". Refereed version accepted for publicatio

    Theoretical study of electric field-dependent polaron-type mobility in conjugated polymers

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    We have used a self-consistent quantum molecular dynamics approach to calculate the mobility of both positive and negative polaron-type carriers on solated chains of poly(p-phenylene vinylene) (PPV) and some of its derivatives and the dependence of their mobility on the applied electric field. Our results suggest that polaron-type mobility along most of these polymer chains has a clear dependence on the electric field which is quite different from the result derived for bulk PPV-based materials.Fundação para a Ciência e a Tecnologia (FCT) Programa Operacional “Ciência , Tecnologia, Inovação” – POCTI/CTM/41574/2001, CONC-REEQ/443/EEI/2001 e SFRH/BD/11231/200

    Purity of Gaussian states: measurement schemes and time-evolution in noisy channels

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    We present a systematic study of the purity for Gaussian states of single-mode continuous variable systems. We prove the connection of purity to observable quantities for these states, and show that the joint measurement of two conjugate quadratures is necessary and sufficient to determine the purity at any time. The statistical reliability and the range of applicability of the proposed measurement scheme is tested by means of Monte Carlo simulated experiments. We then consider the dynamics of purity in noisy channels. We derive an evolution equation for the purity of general Gaussian states both in thermal and squeezed thermal baths. We show that purity is maximized at any given time for an initial coherent state evolving in a thermal bath, or for an initial squeezed state evolving in a squeezed thermal bath whose asymptotic squeezing is orthogonal to that of the input state.Comment: 9 Pages, 6 Figures; minor errors correcte

    Magnetic properties of exactly solvable doubly decorated Ising-Heisenberg planar models

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    Applying the decoration-iteration procedure, we introduce a class of exactly solvable doubly decorated planar models consisting both of the Ising- and Heisenberg-type atoms. Exact solutions for the ground state, phase diagrams and basic physical quantities are derived and discussed. The detailed analysis of the relevant quantities suggests the existence of an interesting quantum antiferromagnetic phase in the system.Comment: 9 pages, 9 figures, submitted to Physical Review
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