96 research outputs found
Validity of adiabaticity in Cavity QED
This paper deals with the concept of adiabaticity for fully quantum
mechanically cavity QED models. The physically interesting cases of Gaussian
and standing wave shapes of the cavity mode are considered. An analytical
approximate measure for adiabaticity is given and compared with numerical wave
packet simulations. Good agreement is obtained where the approximations are
expected to be valid. Usually for cavity QED systems, the large atom-field
detuning case is considered as the adiabatic limit. We, however, show that
adiabaticity is also valid, for the Gaussian mode shape, in the opposite limit.
Effective semiclassical time dependent models, which do not take into account
the shape of the wave packet, are derived. Corrections to such an effective
theory, which are purely quantum mechanical, are discussed. It is shown that
many of the results presented can be applied to time dependent two-level
systems.Comment: 10 pages, 9 figure
Relativistic and Radiative Corrections to the Mollow Spectrum
The incoherent, inelastic part of the resonance fluorescence spectrum of a
laser-driven atom is known as the Mollow spectrum [B. R. Mollow, Phys. Rev.
188, 1969 (1969)]. Starting from this level of description, we discuss
theoretical foundations of high-precision spectroscopy using the resonance
fluorescence light of strongly laser-driven atoms. Specifically, we evaluate
the leading relativistic and radiative corrections to the Mollow spectrum, up
to the relative orders of (Z alpha)^2 and alpha(Z alpha)^2, respectively, and
Bloch-Siegert shifts as well as stimulated radiative corrections involving
off-resonant virtual states. Complete results are provided for the hydrogen
1S-2P_{1/2} and 1S-2P_{3/2} transitions; these include all relevant correction
terms up to the specified order of approximation and could directly be compared
to experimental data. As an application, the outcome of such experiments would
allow for a sensitive test of the validity of the dressed-state basis as the
natural description of the combined atom-laser system.Comment: 20 pages, 1 figure; RevTe
Self-Energy Correction to the Two-Photon Decay Width in Hydrogenlike Atoms
We investigate the gauge invariance of the leading logarithmic radiative
correction to the two-photon decay width in hydrogenlike atoms. It is shown
that an effective treatment of the correction using a Lamb-shift "potential"
leads to equivalent results in both the length as well as the velocity gauges
provided all relevant correction terms are taken into account. Specifically,
the relevant radiative corrections are related to the energies that enter into
the propagator denominators, to the Hamiltonian, to the wave functions, and to
the energy conservation condition that holds between the two photons; the form
of all of these effects is different in the two gauges, but the final result is
shown to be gauge invariant, as it should be. Although the actual calculation
only involves integrations over nonrelativistic hydrogenic Green functions, the
derivation of the leading logarithmic correction can be regarded as slightly
more complex than that of other typical logarithmic terms. The dominant
radiative correction to the 2S two-photon decay width is found to be -2.020536
(alpha/pi) (Zalpha)^2 ln[(Zalpha)^-2] in units of the leading nonrelativistic
expression. This result is in agreement with a length-gauge calculation [S. G.
Karshenboim and V. G. Ivanov, e-print physics/9702027], where the coefficient
was given as -2.025(1).Comment: 9 pages, RevTe
Calcific myofibrosis due to pentazocine abuse: a case report
<p>Abstract</p> <p>Introduction</p> <p>Pentazocine, a synthetic narcotic analgesic, is commonly used for the relief of moderate to severe pain secondary to various conditions. It is usually well tolerated; however, adverse effects are not uncommon, especially when higher doses are used and when it is used in a dependent fashion. There have been reports of various complications associated with its use, including skin fibrosis, skin ulceration, abnormal skin pigmentation and symmetrical myopathy with fibrous myopathy. Fibrosis has usually been reported in the muscles at the site of injection of the drug. Being opioid in nature, it has a high abuse potential.</p> <p>Case presentation</p> <p>Here we report a case of pentazocine-induced calcific myofibrosis in a 42-year-old man involving muscles which were not injected with pentazocine.</p> <p>Conclusion</p> <p>This case highlights the care that needs to be taken when prescribing opioid analgesics, such as pentazocine, as routine painkillers. Patients who have history of substance abuse are more likely to abuse other agents, including prescription drugs. Rare consequences such as calcific myofibrosis are devastating and can cause significant lifelong disability.</p
The apicomplexan plastid and its evolution
Protistan species belonging to the phylum Apicomplexa have a non-photosynthetic secondary plastidāthe apicoplast. Although its tiny genome and even the entire nuclear genome has been sequenced for several organisms bearing the organelle, the reason for its existence remains largely obscure. Some of the functions of the apicoplast, including housekeeping ones, are significantly different from those of other plastids, possibly due to the organelleās unique symbiotic origin
Reliability and reproducibility of three-dimensional cephalometric landmarks using CBCT: a systematic review
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