25 research outputs found
Multipole interaction between atoms and their photonic environment
Macroscopic field quantization is presented for a nondispersive photonic
dielectric environment, both in the absence and presence of guest atoms.
Starting with a minimal-coupling Lagrangian, a careful look at functional
derivatives shows how to obtain Maxwell's equations before and after choosing a
suitable gauge. A Hamiltonian is derived with a multipolar interaction between
the guest atoms and the electromagnetic field. Canonical variables and fields
are determined and in particular the field canonically conjugate to the vector
potential is identified by functional differentiation as minus the full
displacement field. An important result is that inside the dielectric a dipole
couples to a field that is neither the (transverse) electric nor the
macroscopic displacement field. The dielectric function is different from the
bulk dielectric function at the position of the dipole, so that local-field
effects must be taken into account.Comment: 17 pages, to be published in Physical Review
Quantum state transformation by dispersive and absorbing four-port devices
The recently derived input-output relations for the radiation field at a
dispersive and absorbing four-port device [T. Gruner and D.-G. Welsch, Phys.
Rev. A 54, 1661 (1996)] are used to derive the unitary transformation that
relates the output quantum state to the input quantum state, including
radiation and matter and without placing frequency restrictions. It is shown
that for each frequency the transformation can be regarded as a well-behaved
SU(4) group transformation that can be decomposed into a product of U(2) and
SU(2) group transformations. Each of them may be thought of as being realized
by a particular lossless four-port device. If for narrow-bandwidth radiation
far from the medium resonances the absorption matrix of the four-port device
can be disregarded, the well-known SU(2) group transformation for a lossless
device is recognized. Explicit formulas for the transformation of Fock-states
and coherent states are given.Comment: 24 pages, RevTe
Robust Entanglement in Atomic Systems via Lambda-Type Processes
It is shown that the system of two three-level atoms in
configuration in a cavity can evolve to a long-lived maximum entangled state if
the Stokes photons vanish from the cavity by means of either leakage or
damping. The difference in evolution picture corresponding to the general model
and effective model with two-photon process in two-level system is discussed.Comment: 10 pages, 3 figure
Quantitative conditional quantum erasure in two-atom resonance fluorescence
We present a conditional quantum eraser which erases the a priori knowledge
or the predictability of the path a photon takes in a Young-type double-slit
experiment with two fluorescent four-level atoms. This erasure violates a
recently derived erasure relation which must be satisfied for a conventional,
unconditional quantum eraser that aims to find an optimal sorting of the system
into subensembles with particularly large fringe visibilities. The conditional
quantum eraser employs an interaction-free, partial which-way measurement which
not only sorts the system into optimal subsystems with large visibility but
also selects the appropriate subsystem with the maximum possible visibility. We
explain how the erasure relation can be violated under these circumstances.Comment: Revtex4, 12pages, 4 eps figures, replaced with published version,
changes in Sec. 3, to appear in Physical Review
Exposure and dose assessment to particle components among an elderly population
People spend the majority of their time indoors and the composition and toxicity of indoor particles is
very complex and present significant differences comparing with outdoor aerosols. Consequently,
ambient particles cannot represent a real exposure. The aim of this work was to determine the daily
exposure and the daily inhaled dose to particle components of elders living in Elderly Care Centers. A
questionnaire was applied to 193 institutionalized elders in order to achieve their daily time pattern and
to define the micro-environments where PM10 and its components (carbonaceous components and trace
elements) were assessed. Daily exposure was calculated by integrating the elder's time spend in each
micro-environment and the concentration of the pollutants for the period of interest. This parameter,
together with the inhalation rate and the standard body weight, were used to calculate the daily inhaled
dose. PM10 daily exposure and daily inhaled dose ranged between 11 e 16 mg m 3 and 20 10 3 e
28 10 3 mg kg 1, respectively. This work not only allowed a fully quantification of the magnitude of the
elders exposure, but also showed that the assessment of the integrated exposure to PM components is
determinant to accomplish the dose inhaled by elders living in ECCs
Characterization of the oils from various parts of Talauma gioi Aug. Chev. (Magnoliaceae) from Vietnam
The chemical composition of the essential oils, isolated by hydrodistillation from various parts (leaves, trunk, bark, fruit pulp and kernels) of Talauma giot from Vietnam, was analyzed for the first time by a combination of GC and GC/MS. The major constituents of the fruit pulp and kernel oils were found to be safrole (70.2% and 72.9%) and methyl eugenol (24.2% and 18.5%), respectively. Camphor (23.8%) was the main constituent of the trunk oil. The bark oil contained mainly camphor 05.7%), safrole (14.3%), beta-caryophyllene (15.6%) and elemicin (13.7%). The leaf oil contained elemicin (46.3%) and beta-caryophyllene (16.9'1;6) as major components
Medication errors in Vietnamese hospitals: prevalence, potential outcome and associated factors
Background Evidence from developed countries showed that medication errors are common and harmful. Little is known about medication errors in resource-restricted settings, including Vietnam. Objectives To determine the prevalence and potential clinical outcome of medication preparation and administration errors, and to identify factors associated with errors. Methods This was a prospective study conducted on six wards in two urban public hospitals in Vietnam. Data of preparation and administration errors of oral and intravenous medications was collected by direct observation, 12 hours per day on 7 consecutive days, on each ward. Multivariable logistic regression was applied to identify factors contributing to errors. Results In total, 2060 out of 5271 doses had at least one error. The error rate was 39.1%(95% confidence interval 37.8%- 40.4%). Experts judged potential clinical outcomes as minor, moderate, and severe in 72 (1.4%), 1806 (34.2%) and 182 (3.5%) doses. Factors associated with errors were drug characteristics (administration route, complexity of preparation, drug class; all p values <0.001), and administration time (drug round, p = 0.023; day of the week, p = 0.024). Several interactions between these factors were also significant. Nurse experience was not significant. Higher error rates were observed for intravenous medications involving complex preparation procedures and for anti-infective drugs. Slightly lower medication error rates were observed during afternoon rounds compared to other rounds. Conclusions Potentially clinically relevant errors occurred in more than a third of all medications in this large study conducted in a resource-restricted setting. Educational interventions, focusing on intravenous medications with complex preparation procedure, particularly antibiotics, are likely to improve patient safety