454 research outputs found
Studies of vertical wind profiles at Cape Kennedy, Florida Final report
Vertical wind profiles spectral analysis and numerical wind forecasts at Cape Kenned
Increased level of serum cytokines, chemokines and adipokines in patients with schizophrenia is associated with disease and metabolic syndrome
SummaryAt present there are strong indications of a shared vulnerability factor for schizophrenia (SZ), diabetes and the metabolic syndrome (metS). In this study we focus on an aberrantly activated monocyte/macrophage system as the shared factor.We measured in SZ patients (n=144), the serum levels of monocyte/macrophage cytokines/chemokines/adipokines CCL2, CCL4, IL-1β, TNF-α, IL-6, PTX3, leptin, adiponectin, PAI-1, OPG and ICAM-1 and compared these levels to healthy controls (HC) (n=138). Using multivariate analysis, we studied the effect of the presence of the disease SZ, the components of the metS including BMI, the levels of lipids (HDL cholesterol and triglycerides (TG)), diabetes (hyperglycemia) and the use of antipsychotic medication, on the serum levels of these immune compounds.We found all measured immune compounds with the exception of PAI-1 and OPG to be elevated in the SZ patient population. Multivariate analysis showed that elevations were linked to gender (ICAM-1, leptin, TNF-α and adiponectin), an increased BMI (leptin, adiponectin), hyperglycemia/diabetes (CCL4, and OPG), reduced HDL-cholesterol or increased levels of TG (adiponectin and PTX3) or the metS (CCL2, leptin and adiponectin). IL-1β and IL-6 were the only immune compounds raised in the serum of patients not affected by any of the included factors.Although many of the immune compounds were found linked to (components of) the metS, the most dominant linkage was found with the disease schizophrenia, confirming earlier reports on increased monocyte/macrophage activation as a key component for understanding the pathogenesis of schizophrenia
Statistical properties of spontaneous emission near a rough surface
We study the lifetime of the excited state of an atom or molecule near a
plane surface with a given random surface roughness. In particular, we discuss
the impact of the scattering of surface modes within the rough surface. Our
study is completed by considering the lateral correlation length of the decay
rate and the variance discussing its relation to the C0 correlation
Measuring the quantum efficiency of single radiating dipoles using a scanning mirror
Using scanning probe techniques, we show the controlled manipulation of the
radiation from single dipoles. In one experiment we study the modification of
the fluorescence lifetime of a single molecular dipole in front of a movable
silver mirror. A second experiment demonstrates the changing plasmon spectrum
of a gold nanoparticle in front of a dielectric mirror. Comparison of our data
with theoretical models allows determination of the quantum efficiency of each
radiating dipole.Comment: 4 pages, 4 figure
A multiple-scattering approach to interatomic interactions and superradiance in inhomogeneous dielectrics
The dynamics of a collection of resonant atoms embedded inside an
inhomogeneous nondispersive and lossless dielectric is described with a dipole
Hamiltonian that is based on a canonical quantization theory. The dielectric is
described macroscopically by a position-dependent dielectric function and the
atoms as microscopic harmonic oscillators. We identify and discuss the role of
several types of Green tensors that describe the spatio-temporal propagation of
field operators. After integrating out the atomic degrees of freedom, a
multiple-scattering formalism emerges in which an exact Lippmann-Schwinger
equation for the electric field operator plays a central role. The equation
describes atoms as point sources and point scatterers for light. First,
single-atom properties are calculated such as position-dependent
spontaneous-emission rates as well as differential cross sections for elastic
scattering and for resonance fluorescence. Secondly, multi-atom processes are
studied. It is shown that the medium modifies both the resonant and the static
parts of the dipole-dipole interactions. These interatomic interactions may
cause the atoms to scatter and emit light cooperatively. Unlike in free space,
differences in position-dependent emission rates and radiative line shifts
influence cooperative decay in the dielectric. As a generic example, it is
shown that near a partially reflecting plane there is a sharp transition from
two-atom superradiance to single-atom emission as the atomic positions are
varied.Comment: 18 pages, 4 figures, to appear in Physical Review
Observation of modified radiative properties of cold atoms in vacuum near a dielectric surface
We have observed a distance-dependent absorption linewidth of cold Rb
atoms close to a dielectric-vacuum interface. This is the first observation of
modified radiative properties in vacuum near a dielectric surface. A cloud of
cold atoms was created using a magneto-optical trap (MOT) and optical molasses
cooling. Evanescent waves (EW) were used to observe the behavior of the atoms
near the surface. We observed an increase of the absorption linewidth with up
to 25% with respect to the free-space value. Approximately half the broadening
can be explained by cavity-quantum electrodynamics (CQED) as an increase of the
natural linewidth and inhomogeneous broadening. The remainder we attribute to
local Stark shifts near the surface. By varying the characteristic EW length we
have observed a distance dependence characteristic for CQED.Comment: 6 pages, 6 figures, some minor revision
Size-Dependence of the Wavefunction of Self-Assembled Quantum Dots
The radiative and non-radiative decay rates of InAs quantum dots are measured
by controlling the local density of optical states near an interface. From
time-resolved measurements we extract the oscillator strength and the quantum
efficiency and their dependence on emission energy. From our results and a
theoretical model we determine the striking dependence of the overlap of the
electron and hole wavefunctions on the quantum dot size. We conclude that the
optical quality is best for large quantum dots, which is important in order to
optimally tailor quantum dot emitters for, e.g., quantum electrodynamics
experiments.Comment: 5 pages, 3 figure
Strongly Coupled Matter-Field and Non-Analytic Decay Rate of Dipole Molecules in a Waveguide
The decay rate \gam of an excited dipole molecule inside a waveguide is
evaluated for the strongly coupled matter-field case near a cutoff frequency
\ome_c without using perturbation analysis. Due to the singularity in the
density of photon states at the cutoff frequency, we find that \gam depends
non-analytically on the coupling constant as . In contrast
to the ordinary evaluation of \gam which relies on the Fermi golden rule
(itself based on perturbation analysis), \gam has an upper bound and does not
diverge at \ome_c even if we assume perfect conductance in the waveguide
walls. As a result, again in contrast to the statement found in the literature,
the speed of emitted light from the molecule does not vanish at \ome_c and is
proportional to which is on the order of m/s for
typical dipole molecules.Comment: 4 pages, 2 figure
A Comparison Of The Methods Of Studying The Spectra Of The Ash2 Radical
The first studies of the A-B electronic band system of the AsH and AsD radicals were made at Sheffield University in the period from1966 to 1968 by Dixon, Duxbury and Lamberton using flash photolysis of arsine and deuterated arsine. The bands have a complex rotational structure associated with that of an asymmetric rotor. Band centres of the 0,v,0-0,0,0 progression were identified for v'=0 tp v'=5, although only the structure of the bands from v'=1 to 3 was analysed in detail. After a long time interval in 1986 a low resolution emission spectrum of AsH was recorded by NI et al. However, it was not until 2007 that He and Clouthier studied the electronic transition of jet-cooled AsH using laser induced fluorescence and wavelength-resolved emission. Following on from this in 2009 Zhao and colleagues recorded absorption spectra of the AsH radical by cavity ringdown spectroscopy. Finally in 2012 Grimminger and Clouthier recorded the equivalent transitions in AsD and AsHD. They also carried out ab initio calculations. By comparing the recent spectroscopic results with those of Dixon et al, we wish to show the complementarity of the different methods for understanding the behaviour of AsH and AsD radicals
An activated set point of T-cell and monocyte inflammatory networks in recent-onset schizophrenia patients involves both pro- and anti-inflammatory forces
We recently described a pro-inflammatory gene expression signature in the monocytes of 60% of patients with recent-onset schizophrenia (SCZ). Here we investigated whether the T-cell system is also in a pro-inflammatory state. A detailed fluorescence-activated cell sorting (FACS) analysis, e. g. of CD3(+) CD25(+) T cells, IFN-gamma(+), IL-4(+), IL-17A(+) (CD4(+)) lymphocytes and CD4(+) CD25(high)FoxP3(+) regulatory T cells, was performed on peripheral blood of 26 patients with recent-onset SCZ (in 19 of whom the inflammatory gene expression signature of the monocyte had been determined) and in age-/gender-matched healthy controls. Various relevant T-cell cytokines, e.g. sCD25, IFN-gamma, IL-17A and IL-4, were measured in serum by a multiplex assay. We detected : (a) not only higher percentages of pro-inflammatory-prone monocytes, activated CD3(+) CD25(+) T cells and pro-inflammatory Th17 cells in patients, but also higher percentages of anti-inflammatory CD4(+) CD25(high)FoxP3(+) regulatory T cells and IL-4(+) lymphocytes; (b) that this activated T-cell set point was reflected in significantly raised serum levels of sCD25; (c) that the up-regulation of IL-4(+)-containing lymphocytes was predominantly found in patients characterized by a monocyte pro-inflammatory set point; and (d) that regulatory T-cell and Th17-cell numbers were higher in patients irrespective of the pro-inflammatory state of the monocytes. Our data do not support the concept that the T-cell system is in a simple pro-inflammatory state in recent-onset SCZ, but do show that the monocyte and T-cell networks are activated and involve both pro-and anti-inflammatory forces. This suggests control within an activated inflammatory system
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