419 research outputs found
generalized Robin boundary conditions and quantum vacuum fluctuations
The effects induced by the quantum vacuum fluctuations of one massless real
scalar field on a configuration of two partially transparent plates are
investigated. The physical properties of the infinitely thin plates are
simulated by means of Dirac- point interactions. It is
shown that the distortion caused on the fluctuations by this external
background gives rise to a generalization of Robin boundary conditions. The
-operator for potentials concentrated on points with non defined parity is
computed with total generality. The quantum vacuum interaction energy between
the two plates is computed using the formula to find positive, negative,
and zero Casimir energies. The parity properties of the
potential allow repulsive quantum vacuum force between identical plates.Comment: 21 pages and 11 figures. PhysRev
Quantum scalar fields in the half-line. A heat kernel/zeta function approach
In this paper we shall study vacuum fluctuations of a single scalar field
with Dirichlet boundary conditions in a finite but very long line. The spectral
heat kernel, the heat partition function and the spectral zeta function are
calculated in terms of Riemann Theta functions, the error function, and
hypergeometric PFQ functions.Comment: Latex file, 11 pages, 7 figure
Two-point one-dimensional - interactions: non-abelian addition law and decoupling limit
In this contribution to the study of one dimensional point potentials, we
prove that if we take the limit on a potential of the type
, we
obtain a new point potential of the type , when and are related to , , and
by a law having the structure of a group. This is the Borel subgroup of
. We also obtain the non-abelian addition law from the
scattering data. The spectra of the Hamiltonian in the exceptional cases
emerging in the study are also described in full detail. It is shown that for
the , values of the couplings the
singular Kurasov matrices become equivalent to Dirichlet at one side of the
point interaction and Robin boundary conditions at the other side
Therapeutic Drug Monitoring of Antifungal Drugs: Another Tool to Improve Patient Outcome?
Introduction: This study aimed to examine the relationship among adequate dose, serum concentration and clinical outcome in a non-selected group of hospitalized patients receiving antifungals. Methods: Prospective cross-sectional study performed between March 2015 and June 2015. Dosage of antifungals was considered adequate according to the IDSA guidelines, whereas trough serum concentrations (determined with HPLC) were considered adequate as follows: fluconazole > 11\ua0\ub5g/ml, echinocandins > 1\ua0\ub5g/ml, voriconazole 1\u20135.5\ua0\ub5g/ml and posaconazole > 0.7\ua0\ub5g/ml. Results: During the study period, 84 patients (65.4% male, 59.6\ua0years) received antifungals for prophylaxis (40.4%), targeted (31.0%) and empirical therapy (28.6%). The most frequent drug was micafungin (28/84; 33.3%) followed by fluconazole (23/84; 27.4%), voriconazole (15/84; 17.9%), anidulafungin (8/84; 9.5%), posaconazole (7/84; 8.3%) and caspofungin (3/84; 3.6%). Considerable interindividual variability was observed for all antifungals with a large proportion of the patients (64.3%) not attaining adequate trough serum concentrations, despite receiving an adequate antifungal dose. Attaining the on-target serum antifungal level was significantly associated with a favorable clinical outcome (OR = 0.02; 95% CI 0.01\u20130.64; p = 0.03), whereas the administration of an adequate antifungal dosage was not. Conclusions: With the standard antifungal dosage, a considerable proportion of patients have low drug concentrations, which are associated with poor clinical outcome
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