13,944 research outputs found

    Nitrification-denitrification in WSP: a mechanism for permanent nitrogen removal in maturation ponds

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    A pilot-scale primary maturation pond was spiked with 15N-labelled ammonia (15NH4Cl) and 15N labelled nitrite (Na15NO2), in order to improve current understanding of the dynamics of inorganic nitrogen transformations and removal in WSP systems. Stable isotope analysis of δ15N showed that nitrification could be considered as an intermediate step in WSP, which is masked by simultaneous denitrification, under conditions of low algal activity. Molecular microbiology analysis showed that denitrification can be considered a feasible mechanism for permanent nitrogen removal in WSP, which may be supported either by ammonia-oxidising bacteria (AOB) or by methanotrophs, in addition to nitrite-oxidising bacteria (NOB). However, the relative supremacy of the denitrification process over other nitrogen removal mechanisms (e.g., biological uptake) depends upon phytoplanktonic activity

    Evidence for fast thermalization in the plane-wave matrix model

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    We perform a numerical simulation of the classical evolution of the plane-wave matrix model with semiclassical initial conditions. Some of these initial conditions thermalize and are dual to a black hole forming from the collision of D-branes in the plane wave geometry. In particular, we consider a large fuzzy sphere (a D2-brane) plus a single eigenvalue (a D0-particle) going exactly through the center of the fuzzy sphere and aimed to intersect it. Including quantum fluctuations of the off-diagonal modes in the initial conditions, with sufficient kinetic energy the configuration collapses to a small size. We also find evidence for fast thermalization: rapidly decaying autocorrelation functions at late times with respect to the natural time scale of the system.Comment: 5 pages, 5 figures, revtex4 format; v2: minor typos fixed; v3: 8 pages, 9 figures, minor changes, includes a supplement as appeared on PR

    Experimental recovery of a qubit from partial collapse

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    We describe and implement a method to restore the state of a single qubit, in principle perfectly, after it has partially collapsed. The method resembles the classical Hahn spin-echo, but works on a wider class of relaxation processes, in which the quantum state partially leaves the computational Hilbert space. It is not guaranteed to work every time, but successful outcomes are heralded. We demonstrate using a single trapped ion better performance from this recovery method than can be obtained employing projection and post-selection alone. The demonstration features a novel qubit implementation that permits both partial collapse and coherent manipulations with high fidelity.Comment: 5 pages, 3 figure

    Nonperturbative Vertices in Supersymmetric Quantum Electrodynamics

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    We derive the complete set of supersymmetric Ward identities involving only two- and three- point proper vertices in supersymmetric QED. We also present the most general form of the proper vertices consistent with both the supersymmetric and U(1) gauge Ward identities. These vertices are the supersymmetric equivalent of the non supersymmetric Ball-Chiu vertices.Comment: seventeen pages late

    Healthcare Barriers of Residents at a Subsidized Housing Community

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    Introduction: Despite expanded healthcare programs, the low income and elderly lack coverage of vision, hearing, and dental services. Community services are often asked to fill these gaps. To evaluate the situation in Burlington, VT, we surveyed staff and residents in Burlington Housing Authority (BHA) subsidized housing to (1) identify gaps in healthcare coverage and (2) assess barriers to accessing those services in this population.https://scholarworks.uvm.edu/comphp_gallery/1207/thumbnail.jp

    Tuberculous dactylitis—an easily missed diagnosis

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    The prevalence of tuberculosis (TB) continues to rise worldwide. Current migration patterns and increased travel to high-prevalence TB countries will result in more frequent presentations of less common forms of TB. Tuberculous dactylitis, a form of tuberculous osteomyelitis, is well recognised in countries with a high prevalence of TB. We provide a systematic review of all published cases of tuberculous dactylitis in children and adolescents and describe a case to illustrate the typical features of the disease. Our review revealed 37 cases of tuberculous dactylitis in children and adolescents, all reported in the last 17years. Children less than 10 years of age are most frequently affected and the hand is the most commonly affected site. Concurrent pulmonary TB is present in a fifth of cases and systemic symptoms are usually absent. Positive TST and IGRA support the presumptive diagnosis, but cannot be used as rule-out tests. The definitive diagnosis relies on the detection M. tuberculosis by PCR or culture. Treatment should comprise of a standard three to four drug anti-tuberculous regimen. The optimal treatment duration remains unknown. Surgery has a limited role in the treatment in general but may play a supportive role, and curettage of the cavity has been recommended for avascular lesion

    On dynamical mass generation in three dimensional supersymmetric U(1) gauge field theory

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    We investigate and contrast the non-perturbative infra red structure of N=1 and N=2 supersymmetric non-compact U(1) gauge field theory in three space-time dimensions with N matter flavours. We study the Dyson-Schwinger equations in a general gauge using superfield formalism; this ensures that supersymmetry is kept manifest, though leads to spurious infra red divergences which we have to avoid carefully. In the N=1 case the superfield formalism allows us to choose a vertex which satisfies the U(1) Ward identity exactly, and we find the expected critical behaviour in the wavefunction renormalization and strong evidence for the existence of a gauge independent dynamically generated mass, but with no evidence for a critical flavour number. We study the N=2 model by dimensional reduction from four dimensional N=1 electrodynamics, and we refine the old gauge dependence argument that there is no dynamical mass generation. We recognize that the refinement only holds after dimensional reduction.Comment: 32 pages RevTeX; 3 axodraw figures include
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