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Applicability of Winthrop Score for the Diagnosis of Influenza A in the Emergency Department of Hospital Pablo Arturo Suárez, January to March of 2018
Introduction: In 2010, the Department of Infectious Diseases at Winthrop University Hospital designed a score system for the diagnosis of Legionella pneumonia. In this study, we applied the score to patients with acute respiratory symptoms suspected of having type A influenza. The identification of patients at medium to high risk of Influenza A allows for early initiation of treatment.Objective: To study the applicability of the Winthrop score for the diagnosis of Influenza A.Methodology: A prospective cohort study was performed in 2018 at Hospital Pablo Arturo Suárez, in Quito, Ecuador. Patients 0 to 100 years old presenting to the emergency department with influenza-like illness in January-March of 2018 were included in the study. Winthrop score results were then compared with the result of the reverse transcription polymerase chain reaction (RT-PCR) for influenza A, the gold standard for diagnosis. Sensitivity, specificity, positive and negative predictive values, and likelihood ratios were used to establish the diagnostic performance of this point system for influenza A within the sample at large and in subgroup analyses by age (<5 years, 5-65 years, and >65 years) and comorbidities.Results: 149 patients were enrolled in the study period. The study population included 81 males (54.4%) and the majority of patients were less than 5 years of age (N=85, 57.0%). Furthermore, almost one-third of the patients were less than one year old (N=38, 25.5%). According to the Winthrop point system, 68.5% of the cases had a low probability of having influenza (n = 102), 8.7% of cases had a medium probability (n = 13) and 22.8 % of cases had a high probability (n = 34). The RT-PCR test for influenza was positive for 26.2% of patients (n = 39). The Winthrop point system had a sensitivity of 97.4%, specificity of 91.8%, positive predictive value of 80.8%, negative predictive value of 99.0%, positive likelihood ratio of 11.9, and negative likelihood ratio of 35.8 in the total study population. For children under 5 years, a sensitivity of 100%, specificity of 96.3%, positive predictive value of 77.7%, negative predictive value of 100%, positive likelihood ratio of 27, and negative likelihood ratio of 0. In patients older than 6 years, a sensitivity of 96.9%, specificity of 89%, positive predictive value of 84.21%, negative predictive value of 98%, positive likelihood ratio of 8.8, and negative likelihood ratio of 29.4. Testing in patients over 65 years had a sensitivity of 100%, specificity of 90%, positive predictive value of 87.5%, negative predictive value of 100%, positive likelihood ratio of 10 and negative likelihood ratio of 0. Finally, patients with comorbidities had a sensitivity of 90%, specificity of 88.24%, positive predictive value of 81.82%, negative predictive value of 93.75%, positive likelihood ratio of 7.65, and negative likelihood ratio of 8.82.Conclusions: The Winthrop score performed well in predicting Influenza A in patients with acute respiratory symptoms. This score may be useful in settings were Influenza A PCR testing is unavailable
Leaky modes of waveguides as a classical optics analogy of quantum resonances
A classical optics waveguide structure is proposed to simulate resonances of
short range one-dimensional potentials in quantum mechanics. The analogy is
based on the well known resemblance between the guided and radiation modes of a
waveguide with the bound and scattering states of a quantum well. As resonances
are scattering states that spend some time in the zone of influence of the
scatterer, we associate them with the leaky modes of a waveguide, the latter
characterized by suffering attenuation in the direction of propagation but
increasing exponentially in the transverse directions. The resemblance is
complete since resonances (leaky modes) can be interpreted as bound states
(guided modes) with definite lifetime (longitudinal shift). As an immediate
application we calculate the leaky modes (resonances) associated with a
dielectric homogeneous slab (square well potential) and show that these modes
are attenuated as they propagate.Comment: The title has been modified to describe better the contents of the
article. Some paragraphs have been added to clarify the result
Superpositions of bright and dark solitons supporting the creation of balanced gain and loss optical potentials
Bright and dark solitons of the cubic nonlinear Schrodinger equation are used
to construct complex-valued potentials with all-real spectrum. The real part of
these potentials is equal to the intensity of a bright soliton while their
imaginary part is defined by the product of such soliton with its concomitant,
a dark soliton. Considering light propagation in Kerr media, the real part of
the potential refers to the self-focusing of the signal and the imaginary one
provides the system with balanced gain-and-loss rates.Comment: 6 figures, 17 pages, LaTeX file. The manuscript has been re-organized
(abstract, introduction and conclusions rewritten), and it now includes an
appendix with detailed calculations of some relevant results reported in the
paper. New references were adde
Dynamical Equations, Invariants and Spectrum Generating Algebras of Mechanical Systems with Position-Dependent Mass
We analyze the dynamical equations obeyed by a classical system with
position-dependent mass. It is shown that there is a non-conservative force
quadratic in the velocity associated to the variable mass. We construct the
Lagrangian and the Hamiltonian for this system and find the modifications
required in the Euler-Lagrange and Hamilton's equations to reproduce the
appropriate Newton's dynamical law. Since the Hamiltonian is not time
invariant, we get a constant of motion suited to write the dynamical equations
in the form of the Hamilton's ones. The time-dependent first integrals of
motion are then obtained from the factorization of such a constant. A canonical
transformation is found to map the variable mass equations to those of a
constant mass. As particular cases, we recover some recent results for which
the dependence of the mass on the position was already unnoticed, and find new
solvable potentials of the P\"oschl-Teller form which seem to be new. The
latter are associated to either the su(1,1) or the su(2) Lie algebras depending
on the sign of the Hamiltonian
Completeness and Nonclassicality of Coherent States for Generalized Oscillator Algebras
The purposes of this work are (1) to show that the appropriate
generalizations of the oscillator algebra permit the construction of a wide set
of nonlinear coherent states in unified form; and (2) to clarify the likely
contradiction between the nonclassical properties of such nonlinear coherent
states and the possibility of finding a classical analog for them since they
are P-represented by a delta function. In (1) we prove that a class of
nonlinear coherent states can be constructed to satisfy a closure relation that
is expressed uniquely in terms of the Meijer G-function. This property
automatically defines the delta distribution as the P-representation of such
states. Then, in principle, there must be a classical analog for them. Among
other examples, we construct a family of nonlinear coherent states for a
representation of the su(1,1) Lie algebra that is realized as a deformation of
the oscillator algebra. In (2), we use a beam splitter to show that the
nonlinear coherent states exhibit properties like anti-bunching that prohibit a
classical description for them. We also show that these states lack second
order coherence. That is, although the P-representation of the nonlinear
coherent states is a delta function, they are not full coherent. Therefore, the
systems associated with the generalized oscillator algebras cannot be
considered `classical' in the context of the quantum theory of optical
coherence.Comment: 26 pages, 10 figures, minor changes, misprints correcte
Localization analysis under dynamic loading
A finite element method proposed by Ortiz et al. (1987) is used to study shear band formation in rate dependent and rate independent pressure sensitive solids under dynamic loading. Under these conditions, shear bands are observed to propagate in an irregular fashion in time and space. In particular, the development of multiple shear bands appears to be a prevalent mechanism of deformation at sufficiently high impact velocities
Disertacion historia politico-legal [Texto impreso] : en que se hace ver el origen de la agricultura, su dignidad y utilidades...
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