52,793 research outputs found

    An investigation of film wavy structure in annular flow using two simultaneous LIF approaches

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    The paper is devoted to development and validation of film thickness measurement techniques in interfacial gas-liquid flows. The specific flow investigated here is that of downwards (co-flowing) annular flow in a vertical pipe, however, many of the observations and findings are transferable to similar flow geometries. Two advanced spatially resolved techniques, namely planar laser-induced fluorescence and brightness-based laser-induced fluorescence , are used simultaneously in the same area of interrogation. A single laser sheet is used to excite fluorescence along one longitudinal section of the pipe, and two cameras (one for each method) are placed at different angles to the plane of the laser sheet in order to independently recover the shape of the interface along this section. This allows us to perform a cross-validation of the two techniques and to analyse their respective characteristics, advantages and shortcomings

    Once more on the Witten index of 3d supersymmetric YM-CS theory

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    The problem of counting the vacuum states in the supersymmetric 3d Yang-Mills-Chern-Simons theory is reconsidered. We resolve the controversy between its original calculation by Witten at large volumes and the calculation based on the evaluation of the effective Lagrangian in the small volume limit. We show that the latter calculation suffers from uncertainties associated with the singularities in the moduli space of classical vacua where the Born-Oppenheimer approximation breaks down. We also show that these singularities can be accurately treated in the Hamiltonian Born-Oppenheimer method, where one has to match carefully the effective wave functions on the Abelian valley and the wave functions of reduced non-Abelian QM theory near the singularities. This gives the same result as original Witten's calculation.Comment: 27 page

    Study of one-dimensional nature of (Sr,Ba)_2Cu(PO_4)_2 and BaCuP_2O_7 via 31P NMR

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    The magnetic behavior of the low-dimensional phosphates (Sr,Ba)_2 Cu(PO_4)_2 and BaCuP_2O_7 was investigated by means of magnetic susceptibility and ^{31}P nuclear magnetic resonance (NMR) measurements. We present here the NMR shift K(T), the spin-lattice 1/T_1 and spin-spin 1/T_2 relaxation-rate data over a wide temperature range 0.02 K < T < 300 K. The T-dependence of the NMR K(T) is well described by the S=1/2 Heisenberg antiferromagnetic chain model with an intrachain exchange of J/k_B = 165 K, 151 K, and 108 K in Sr_2Cu(PO_4)_2, Ba_2Cu(PO_4)_2, and BaCuP_2O_7, respectively. Our measurements suggest the presence of magnetic ordering at 0.8 K in BaCuP_2O_7 (J/k_B = 108 K). For all the samples, we find that 1/T_1 is nearly T-independent at low-temperatures (1 K < T < 10 K), which is theoretically expected for 1D chains when relaxation is dominated by fluctuations of the staggered susceptibility. At high temperatures, 1/T_1 varies nearly linearly with temperature

    Prevalence of Enteropathogens in Dogs Attending 3 Regional Dog Parks in Northern California.

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    BackgroundThe prevalence and risk factors for infection with enteropathogens in dogs frequenting dog parks have been poorly documented, and infected dogs can pose a potential zoonotic risk for owners.Hypothesis/objectivesTo determine the prevalence and risk factors of infection with enteropathogens and zoonotic Giardia strains in dogs attending dog parks in Northern California and to compare results of fecal flotation procedures performed at a commercial and university parasitology laboratory.AnimalsThree-hundred dogs attending 3 regional dog parks in Northern California.MethodsProspective study. Fresh fecal specimens were collected from all dogs, scored for consistency, and owners completed a questionnaire. Specimens were analyzed by fecal centrifugation flotation, DFA, and PCR for detection of 11 enteropathogens. Giardia genotyping was performed for assemblage determination.ResultsEnteropathogens were detected in 114/300 dogs (38%), of which 62 (54%) did not have diarrhea. Frequency of dog park attendance correlated significantly with fecal consistency (P = .0039), but did not correlate with enteropathogen detection. Twenty-seven dogs (9%) were infected with Giardia, and genotyping revealed nonzoonotic assemblages C and D. The frequency of Giardia detection on fecal flotation was significantly lower at the commercial laboratory versus the university laboratory (P = .013), and PCR for Giardia was negative in 11/27 dogs (41%) that were positive on fecal flotation or DFA.Conclusions and clinical importanceEnteropathogens were commonly detected in dogs frequenting dog parks, and infection with Giardia correlated with fecal consistency. PCR detection of Giardia had limited diagnostic utility, and detection of Giardia cysts by microscopic technique can vary among laboratories

    Integrated plasmonic circuitry on a vertical-cavity surface-emitting semiconductor laser platform

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    Integrated plasmonic sources and detectors are imperative in the practical development of plasmonic circuitry for bio- and chemical sensing, nanoscale optical information processing, as well as transducers for high-density optical data storage. Here we show that vertical-cavity surface-emitting lasers (VCSELs) can be employed as an on-chip, electrically pumped source or detector of plasmonic signals, when operated in forward or reverse bias, respectively. To this end, we experimentally demonstrate surface plasmon polariton excitation, waveguiding, frequency conversion and detection on a VCSEL-based plasmonic platform. The coupling efficiency of the VCSEL emission to waveguided surface plasmon polariton modes has been optimized using asymmetric plasmonic nanostructures. The plasmonic VCSEL platform validated here is a viable solution for practical realizations of plasmonic functionalities for various applications, such as those requiring sub-wavelength field confinement, refractive index sensitivity or optical near-field transduction with electrically driven sources, thus enabling the realization of on-chip optical communication and lab-on-a-chip devices

    ABJ(M) Chiral Primary Three-Point Function at Two-loops

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    This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.archiveprefix: arXiv primaryclass: hep-th reportnumber: QMUL-PH-14-10 slaccitation: %%CITATION = ARXIV:1404.1117;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: QMUL-PH-14-10 slaccitation: %%CITATION = ARXIV:1404.1117;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: QMUL-PH-14-10 slaccitation: %%CITATION = ARXIV:1404.1117;%%Article funded by SCOAP

    Ising Model Coupled to Three-Dimensional Quantum Gravity

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    We have performed Monte Carlo simulations of the Ising model coupled to three-dimensional quantum gravity based on a summation over dynamical triangulations. These were done both in the microcanonical ensemble, with the number of points in the triangulation and the number of Ising spins fixed, and in the grand canoncal ensemble. We have investigated the two possible cases of the spins living on the vertices of the triangulation (``diect'' case) and the spins living in the middle of the tetrahedra (``dual'' case). We observed phase transitions which are probably second order, and found that the dual implementation more effectively couples the spins to the quantum gravity.Comment: 11 page

    STRENGTHENING COOPERATION WITH THIRD COUNTRIES IN THE FIELD OF HIGHER EDUCATION. 14388/01 (Presse 437-G), 29 November 2001

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    BACKGROUND: In many European countries, medicines promotion is governed by voluntary codes of practice administered by the pharmaceutical industry under its own system of self-regulation. Involvement of industry organizations in policing promotion has been proposed to deter illicit conduct, but few detailed studies on self-regulation have been carried out to date. The objective of this study was to examine the evidence for promotion and self-regulation in the UK and Sweden, two countries frequently cited as examples of effective self-regulation. METHODS AND FINDINGS: We performed a qualitative content analysis of documents outlining the constitutions and procedures of these two systems. We also gathered data from self-regulatory bodies on complaints, complainants, and rulings for the period 2004-2012. The qualitative analysis revealed similarities and differences between the countries. For example, self-regulatory bodies in both countries are required to actively monitor promotional items and impose sanctions on violating companies, but the range of sanctions is greater in the UK where companies may, for instance, be audited or publicly reprimanded. In total, Swedish and UK bodies ruled that 536 and 597 cases, respectively, were in breach, equating to an average of more than one case/week for each country. In Sweden, 430 (47%) complaints resulted from active monitoring, compared with only two complaints (0.2%) in the UK. In both countries, a majority of violations concerned misleading promotion. Charges incurred on companies averaged €447,000 and €765,000 per year in Sweden and the UK, respectively, equivalent to about 0.014% and 0.0051% of annual sales revenues, respectively. One hundred cases in the UK (17% of total cases in breach) and 101 (19%) in Sweden were highlighted as particularly serious. A total of 46 companies were ruled in breach of code for a serious offence at least once in the two countries combined (n = 36 in the UK; n = 27 in Sweden); seven companies were in serious violation more than ten times each. A qualitative content analysis of serious violations pertaining to diabetes drugs (UK, n = 15; Sweden, n = 6; 10% of serious violations) and urologics (UK, n = 6; Sweden, n = 13; 9%) revealed various types of violations: misleading claims (n = 23; 58%); failure to comply with undertakings (n = 9; 23%); pre-licensing (n = 7; 18%) or off-label promotion (n = 2; 5%); and promotion of prescription drugs to the public (n = 6; 15%). Violations that go undetected or unpunished by self-regulatory bodies are the main limitation of this study, since they are likely to lead to an underestimate of industry misconduct. CONCLUSIONS: The prevalence and severity of breaches testifies to a discrepancy between the ethical standard codified in industry Codes of Conduct and the actual conduct of the industry. We discuss regulatory reforms that may improve the quality of medicines information, such as pre-vetting and intensified active monitoring of promotion, along with larger fines, and giving greater publicity to rulings. But despite the importance of improving regulatory arrangements in an attempt to ensure unbiased medicines information, such efforts alone are insufficient because simply improving oversight and increasing penalties fail to address additional layers of industry bias

    Dynamic communicability predicts infectiousness

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    Using real, time-dependent social interaction data, we look at correlations between some recently proposed dynamic centrality measures and summaries from large-scale epidemic simulations. The evolving network arises from email exchanges. The centrality measures, which are relatively inexpensive to compute, assign rankings to individual nodes based on their ability to broadcast information over the dynamic topology. We compare these with node rankings based on infectiousness that arise when a full stochastic SI simulation is performed over the dynamic network. More precisely, we look at the proportion of the network that a node is able to infect over a fixed time period, and the length of time that it takes for a node to infect half the network.We find that the dynamic centrality measures are an excellent, and inexpensive, proxy for the full simulation-based measures
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