62 research outputs found
Phi-Psi model for Electrodynamics in dielectric media: exact quantisation in the Heisenberg representation
We investigate the quantization in the Heisenberg representation of a model
which represents a simplification of the Hopfield model for dielectric media,
where the electromagnetic field is replaced by a scalar field and the
role of the polarization field is played by a further scalar field . The
model, which is quadratic in the fields, is still characterized by a nontrivial
physical content, as the physical particles correspond to the polaritons of the
standard Hopfield model of condensed matter physics. Causality is also taken
into account and a discussion of the standard interaction representation is
also considered.Comment: 9 page
Quantifying nonlinearity in planar supersonic potential flows
An analysis is presented which allows the engineer to quantitatively estimate the validity
bounds of aerodynamic methods based in linear potential flows a-priori. The development is
limited to quasi-steady planar flows with attached shocks and small body curvature. Perturbation
velocities are parametrised in terms of Mach number and flow turning-angle by means
of a series-expansion for flow velocity based in the method of characteristics. The parametrisation
is used to assess the magnitude of nonlinear term-groupings relative to linear groups in
the full potential equation. This quantification is used to identify dominant nonlinear terms
and to estimate the validity of linearising the potential flow equation at a given Mach number
and flow turning angle. Example applications include the a-priori estimation of the validity
bounds for linear aerodynamic models for supersonic aeroelastic analysis of lifting surfaces
and panels.http://journals.cambridge.org/action/displayJournal?jid=AFR2017-06-30hb2017Mechanical and Aeronautical Engineerin
Aminas biogênicas de cultivares de milho-verde produzidos em sistemas de cultivo orgânico e convencional.
A Prospective Hospital Study to Evaluate the Diagnostic Accuracy of Rapid Diagnostic Tests for the Early Detection of Leptospirosis in Laos.
Leptospirosis is a globally important cause of acute febrile illness, and a common cause of non-malarial fever in Asia, Africa, and Latin America. Simple rapid diagnostic tests (RDTs) are needed to enable health-care workers, particularly in low resource settings, to diagnose leptospirosis early and give timely targeted treatment. This study compared four commercially available RDTs to detect human IgM against Leptospira spp. in a head-to-head prospective evaluation in Mahosot Hospital, Lao PDR. Patients with an acute febrile illness consistent with leptospirosis (N = 695) were included in the study during the 2014 rainy season. Samples were tested with four RDTs: ("Test-it" [Life Assay, Cape Town, South Africa; N = 418]; "Leptorapide" [Linnodee, Ballyclare, Northern Ireland; N = 492]; "Dual Path Platform" [DPP] [Chembio, Medford, NY; N = 530]; and "SD-IgM" [Standard Diagnostics, Yongin, South Korea; N = 481]). Diagnostic performance characteristics were calculated and compared with a composite reference standard combining polymerase chain reaction (PCR) (rrs), microscopic agglutination tests (MATs), and culture. Of all patients investigated, 39/695 (5.6%) were positive by culture, PCR, or MAT. The sensitivity and specificity of the RDTs ranged greatly from 17.9% to 63.6% and 62.1% to 96.8%, respectively. None of the investigated RDTs reached a sensitivity or specificity of > 90% for detecting Leptospira infections on admission. In conclusion, our investigation highlights the challenges associated with Leptospira diagnostics, particularly in populations with multiple exposures. These findings emphasize the need for extensive prospective evaluations in multiple endemic settings to establish the value of rapid tools for diagnosing fevers to allow targeting of antibiotics
Effect of soil tillage, crop rotation and nitrogen application rates on grain yield of spring wheat ( Triticum aestivum L.)
Morphological variation among populations of Hemigrammus coeruleus (Characiformes: Characidae) in a Negro River tributary, Brazilian Amazon
Diet-morphology relationship in the stream-dwelling characid Deuterodon stigmaturus (Gomes, 1947) (Characiformes: Characidae) is partially conditioned by ontogenetic development
Effect of Silicon dioxide coating of acrylic resin surfaces on Candida albicans adhesion.
Acrylic resin has been used in the manufacture of prostheses, however, in the oral cavity, this material starts to retain microorganisms capable of causing gingival inflammation due its porosities. The aim of this study was to evaluate the influence of the use of silicon dioxide as a coating layer applied onto acrylic resin, on the adhesion of Candida albicans (Ca). After the incubation period in Sabouraud Dextrose Broth, a total of 1 ml of the Ca suspension was added to plate wells, each well containing a specimen of acrylic resin. The adhesion ability of Ca on acrylic resin was determined by counting colonies. Three groups (n = 6) of acrylic resin were assessed: with polishing (RP); without polishing (RW); with polishing and coating layer of silicon dioxide (RPC). Ca deposited on the surface of the acrylic resin was also observed using Scanning Electron Microscopy (SEM). Statistical assessment by Kruskal-Wallis and Student-Newman-Keuls Method were done (α = 2%). There was significant difference among the groups. The RPC group showed the lowest growth, with an average of 5.59 Log CFU/cm 2 ; there was a statistically significant difference in relation to group RW, which presented a growth of 6.07 Log CFU/cm 2 and to group RP with 5.91 Log CFU/cm 2 (p < 000.1). SEM images demonstrated that in the RP and RPC group, the surface of the resin had greater regularity, and smaller number of microorganisms. The application of silicon dioxide coating on acrylic resin appears to be a promising alternative, and its use can help in reducing the adhesion of Ca in prostheses
Gender and obesity interaction in quality of life in adults assisted by family doctor program in Niterói, Brazil
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