780 research outputs found
Electromagnetic field quantization in an anisotropic magnetodielectric medium with spatial-temporal dispersion
By modeling a linear, anisotropic and inhomogeneous magnetodielectric medium
with two independent set of harmonic oscillators, electromagnetic field is
quantized in such a medium. The electric and magnetic polarizations of the
medium are expressed as linear combinations of the ladder operators describing
the magnetodielectric medium. The Maxwell and the constitutive equations of the
medium are obtained as the Heisenberg equations of the total system. The
electric and magnetic susceptibilities of the medium are obtained in terms of
the tensors coupling the medium with the electromagnetic field. The explicit
forms of the electromagnetic field operators are obtained in terms of the
ladder operators of the medium.Comment: 18 pages, no figure
Extension of the Huttner-Barnett model to a magnetodielectric medium
The HuttnerBarnett model is extended to a magnetodielectric medium by
adding a new matter field to this model. The eigenoperators for the coupled
system are calculated and electromagnetic field is written in terms of these
operators. The electric and magnetic susceptibility of the medium are
explicitly derived and shown to satisfy the KramersKronig relations. It is
shown that the results obtained in this model are equivalent to the results
obtained from the phenomenological methods.Comment: 25 page
Casimir force in the presence of a magnetodielectric medium
In this article we investigate the Casimir effect in the presence of a medium
by quantizing the Electromagnetic (EM) field in the presence of a
magnetodielectric medium by using the path integral formalism. For a given
medium with definite electric and magnetic susceptibilities, explicit
expressions for the Casimir force are obtained which are in agree with the
original Casimir force between two conducting parallel plates immersed in the
quantum electromagnetic vacuum.Comment: 8 pages, 1 figur
Effects of adenotonsillectomy on plasma inflammatory biomarkers in obese children with obstructive sleep apnea: A community-based study.
BackgroundObesity and obstructive sleep apnea syndrome (OSA) are highly prevalent and frequently overlapping conditions in children that lead to systemic inflammation, the latter being implicated in the various end-organ morbidities associated with these conditions.AimTo examine the effects of adenotonsillectomy (T&A) on plasma levels of inflammatory markers in obese children with polysomnographically diagnosed OSA who were prospectively recruited from the community.MethodsObese children prospectively diagnosed with OSA, underwent T&A and a second overnight polysomnogram (PSG) after surgery. Plasma fasting morning samples obtained after each of the two PSGs were assayed for multiple inflammatory and metabolic markers including interleukin (IL)-6, IL-18, plasminogen activator inhibitor-1 (PAI-1), monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinase-9 (MMP-9), adiponectin, apelin C, leptin and osteocrin.ResultsOut of 122 potential candidates, 100 obese children with OSA completed the study with only one-third exhibiting normalization of their PSG after T&A (that is, apnea-hypopnea index (AHI) ≤1/hour total sleep time). However, overall significant decreases in MCP-1, PAI-1, MMP-9, IL-18 and IL-6, and increases in adropin and osteocrin plasma concentrations occurred after T&A. Several of the T&A-responsive biomarkers exhibited excellent sensitivity and moderate specificity to predict residual OSA (that is, AHI⩾5/hTST).ConclusionsA defined subset of systemic inflammatory and metabolic biomarkers is reversibly altered in the context of OSA among community-based obese children, further reinforcing the concept on the interactive pro-inflammatory effects of sleep disorders such as OSA and obesity contributing to downstream end-organ morbidities
Finite temperature Cherenkov radiation in the presence of a magnetodielectric medium
A canonical approach to Cherenkov radiation in the presence of a
magnetodielectric medium is presented in classical, nonrelativistic and
relativistic quantum regimes. The equations of motion for the canonical
variables are solved explicitly for both positive and negative times. Maxwell
and related constitute equations are obtained. In the large-time limit, the
vector potential operator is found and expressed in terms of the medium
operators. The energy loss of a charged particle, emitted in the form of
radiation, in finite temperature is calculated. A Dirac equation concerning the
relativistic motion of the particle in presence of the magnetodielectric medium
is derived and the relativistic Cherenkov radiation at zero and finite
temperature is investigated. Finally, it is shown that the Cherenkov radiation
in nonrelativistic and relativistic quantum regimes, unlike its classical
counterpart, introduces automatically a cutoff for higher frequencies beyond
which the power of radiation emission is zero.Comment: To be appear in PR
Non-equilibrium entangled steady state of two independent two-level systems
We determine and study the steady state of two independent two-level systems
weakly coupled to a stationary non-equilibrium environment. Whereas this
bipartite state is necessarily uncorrelated if the splitting energies of the
two-level systems are different from each other, it can be entangled if they
are equal. For identical two-level systems interacting with two bosonic heat
baths at different temperatures, we discuss the influence of the baths
temperatures and coupling parameters on their entanglement. Geometric
properties, such as the baths dimensionalities and the distance between the
two-level systems, are relevant. A regime is found where the steady state is a
statistical mixture of the product ground state and of the entangled singlet
state with respective weights 2/3 and 1/3
Entanglement Transfer via XXZ Heisenberg chain with DM Interaction
The role of spin-orbit interaction, arises from the Dzyaloshinski-Moriya
anisotropic antisymmetric interaction, on the entanglement transfer via an
antiferromagnetic XXZ Heisenberg chain is investigated. From symmetrical point
of view, the XXZ Hamiltonian with Dzyaloshinski-Moriya interaction can be
replaced by a modified XXZ Hamiltonian which is defined by a new exchange
coupling constant and rotated Pauli operators. The modified coupling constant
and the angle of rotations are depend on the strength of Dzyaloshinski-Moriya
interaction. In this paper we study the dynamical behavior of the entanglement
propagation through a system which is consist of a pair of maximally entangled
spins coupled to one end of the chain. The calculations are performed for the
ground state and the thermal state of the chain, separately. In both cases the
presence of this anisotropic interaction make our channel more efficient, such
that the speed of transmission and the amount of the entanglement are improved
as this interaction is switched on. We show that for large values of the
strength of this interaction a large family of XXZ chains becomes efficient
quantum channels, for whole values of an isotropy parameter in the region .Comment: 21 pages, 9 figure
Finite temperature Casimir effect in the presence of nonlinear dielectrics
Starting from a Lagrangian, electromagnetic field in the presence of a
nonlinear dielectric medium is quantized using path-integral techniques and
correlation functions of different fields are calculated. The susceptibilities
of the nonlinear medium are obtained and their relation to coupling functions
are determined. Finally, the Casimir energy and force in the presence of a
nonlinear medium at finite temperature is calculated.Comment: 16 pages, 0 figure
Obstructive sleep apnea in Treacher Collins syndrome
The aim of the present study was to investigate the prevalence of obstructive sleep apnea syndrome (OSAS) among the Norwegian population with Treacher Collins syndrome (TCS). A secondary aim was to establish whether TCS phenotype severity is associated with OSAS severity. A prospective case study design was used. Individuals who were 5 years old and above with a known diagnosis of TCS in Norway were invited to participate in a study. The study included genetic testing, medical and dental examinations and polysomnography. All participants demonstrated disturbed respiration during sleep; 18/19 met the diagnostic criteria for OSAS. Subjectively evaluated snoring was not a reliable predictor of OSAS. We found no significant association between TCS phenotype severity and the severity of OSAS. OSAS is common in TCS, but there is no association with the phenotype severity. Individuals diagnosed with TCS must undergo sleep studies to identify the presence of OSAS
Casimir forces in multilayer magnetodielectrics with both gain and loss
A path-integral approach to the quantization of the electromagnetic field in
a linearly amplifying magnetodielectric medium is presented. Two continua of
inverted harmonic oscillators are used to describe the polarizability and
magnetizability of the amplifying medium. The causal susceptibilities of the
amplifying medium, with negative imaginary parts in finite frequency intervals,
are identified and their relation to microscopic coupling functions are
determined. By carefully relating the two-point functions of the field theory
to the optical Green functions, we calculate the Casimir energy and Casimir
forces for a multilayer magnetodielectric medium with both gain and loss. We
point out the essential differences with a purely passive layered medium. For a
single layer, we find different bounds on the Casimir force for fully
amplifying and for lossy media. The force is attractive in both cases, also if
the medium exhibits negative refraction. From our Lagrangian we also derive by
canonical quantization the postulates of the phenomenological theory of
amplifying magnetodielectrics.Comment: 16 pages, and 5 figure
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