6,547 research outputs found
Persistence of small-scale anisotropy of magnetic turbulence as observed in the solar wind
The anisotropy of magnetophydrodynamic turbulence is investigated by using
solar wind data from the Helios 2 spacecraft. We investigate the behaviour of
the complete high-order moment tensors of magnetic field increments and we
compare the usual longitudinal structure functions which have both isotropic
and anisotropic contributions, to the fully anisotropic contribution. Scaling
exponents have been extracted by an interpolation scaling function. Unlike the
usual turbulence in fluid flows, small-scale magnetic fluctuations remain
anisotropic. We discuss the radial dependence of both anisotropy and
intermittency and their relationship.Comment: 7 pages, 2 figures, in press on Europhys. Let
Photon correlations for colloidal nanocrystals and their clusters
Images of semiconductor `dot in rods' and their small clusters are studied by
measuring the second-order correlation function with a spatially resolving ICCD
camera. This measurement allows one to distinguish between a single dot and a
cluster and, to a certain extent, to estimate the number of dots in a cluster.
A more advanced measurement is proposed, based on higher-order correlations,
enabling more accurate determination of the number of dots in a small cluster.
Nonclassical features of the light emitted by such a cluster are analyzed.Comment: 4 pages, 4 figure
Sjogren\u27s Syndrome: Relationship Between Ocular Findings and Parotid Sialograms
This study evaluates the incidence and severity of the ocular findings and its correlation with the parotid gland changes, as demonstrated by sialography, in 82 patients with Sjogren\u27s syndrome. It is shown that the ocular component of the syndrome manifests rather autonomously with respect to the accompanying collagen disease and that there seems to be only a tentative trend towards a positive correlation between the ocular and parotid findings. Sjogren\u27s syndrome immunologically is closer to the collagen diseases than to the so-called organ-specific autoimmune diseases
Correlated Electrons Step-by-Step: Itinerant-to-Localized Transition of Fe Impurities in Free-Electron Metal Hosts
High-resolution photoemission spectroscopy and realistic ab-initio
calculations have been employed to analyze the onset and progression of d-sp
hybridization in Fe impurities deposited on alkali metal films. The interplay
between delocalization, mediated by the free-electron environment, and Coulomb
interaction among d-electrons gives rise to complex electronic configurations.
The multiplet structure of a single Fe atom evolves and gradually dissolves
into a quasiparticle peak near the Fermi level with increasing the host
electron density. The effective multi-orbital impurity problem within the exact
diagonalization scheme describes the whole range of hybridizations.Comment: 10 pages, 4 figure
Superconductivity-Induced Transfer of In-Plane Spectral Weight in Bi2Sr2CaCu2O8: Resolving a Controversy
We present a detailed analysis of the superconductivity-induced
redistribution of optical spectral weight in Bi2Sr2CaCu2O8 near optimal doping.
It confirms the previous conclusion by Molegraaf et al. (Science 66, 2239
(2002)), that the integrated low-frequency spectral weight shows an extra
increase below Tc. Since the region, where the change of the integrated
spectral weight is not compensated, extends well above 2.5 eV, this transfer is
caused by the transfer of spectral weight from interband to intraband region
and only partially by the narrowing of the intraband peak. We show that the
opposite assertion by Boris et al. (Science 304, 708 (2004)) regarding this
compound, is unlikely the consequence of any obvious discrepancies between the
actual experimental data.Comment: ReVTeX, 9 pages, 8 encapsulated postscript figures, several typo's
correcte
The emerging energy web
There is a general need of elaborating energy-effective solutions for managing our increasingly dense interconnected world. The problem should be tackled in multiple dimensions -technology, society, economics, law, regulations, and politics- at different temporal and spatial scales. Holistic approaches will enable technological solutions to be supported by socio-economic motivations, adequate incentive regulation to foster investment in green infrastructures coherently integrated with adequate energy provisioning schemes. In this article, an attempt is made to describe such multidisciplinary challenges with a coherent set of solutions to be identified to significantly impact the way our interconnected energy world is designed and operated. Graphical abstrac
Magnetism and interlayer coupling in fcc Fe/Co films
The magnetism of epitaxial fee Fe films deposited on Co(100) and sandwiched between two Co(100) films was investigated by x-ray magnetic circular dichroism. The dependence of the Fe magnetism on the film thickness is complex and qualitatively similar on Co(100) and in fee Co/Fe/Co(100) trilayers. The fee Fe film magnetization presents a pronounced oscillation, suggesting a partial antiferromagnetic ordering in the 5-10 monolayer thickness range. The fee Fe films mediate an oscillatory, indirect coupling in Co/Fe/Co(100) structures that alternates in correspondence with the changes of the Fe magnetization
Observation of inertial energy cascade in interplanetary space plasma
We show in this article direct evidence for the presence of an inertial
energy cascade, the most characteristic signature of hydromagnetic turbulence
(MHD), in the solar wind as observed by the Ulysses spacecraft. After a brief
rederivation of the equivalent of Yaglom's law for MHD turbulence, we show that
a linear relation is indeed observed for the scaling of mixed third order
structure functions involving Els\"asser variables. This experimental result,
confirming the prescription stemming from a theorem for MHD turbulence, firmly
establishes the turbulent character of low-frequency velocity and magnetic
field fluctuations in the solar wind plasma
Efficacy of oral hyposensitization in allergic contact dermatitis caused by nickel
Background. Nickel contact allergy remains common in Western countries, and the dermatitis may require prolonged treatment. The development of new strategies aimed at improving the quality of life of affected individuals is needed. Objectives. To investigate the efficacy of oral hyposensitization in nickel-allergic individuals and how this affects in vitro T cell responsiveness to the metal. Methods. Twenty-eight nickel-allergic patients received a daily dose of 50 μg of elemental nickel (given as NiSO 4·6H 2O) in cellulose capsules for 3 months. Severity of clinical manifestations, in vivo nickel responsiveness and in vitro T cell responses to the metal were assessed after 1 and 3 months. Results. Twenty-six patients finished the study. In these patients, oral hyposensitization ameliorated clinical manifestations despite continued nickel exposures, and increased the threshold of skin responsiveness to nickel. The 12 enrolled patients in the immunological study showed decreased in vitro T lymphocyte responsiveness to the metal, in terms of both cell proliferation and cytokine release. In the 1-year follow-up, 50% of the patients experienced relapses of the clinical manifestations at sites of topical exposure to nickel. Conclusions. Our study suggested therapeutic efficacy of oral hyposensitization in allergic individuals. Placebo-controlled studies are required to confirm the results and determine the optimal therapeutic regimen for prolonged beneficial effects
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