193 research outputs found
Universal Scaling of Ballistic Magnetoresistance in Magnetic Nanocontacts
We show that ballistic magnetoresistance exhibits universal scaling in atomic or nanometer scale
contacts. Plotting the data as conductance, we find that, if the maximum magnetoconductance is
normalized to unity and the conductance is scaled with the conductivity of the bulk material, the data
fall in a narrow region, independent of the nanocontact materials, for our four data sets and four from
the literature. The results agree with a theory that takes into account spin-scattering within a magneticdomain
wall
Shell model half-lives for r-process N=82 nuclei
We have performed shell-model calculations of the half-lives and
neutron-branching probabilities of the r-process waiting point nuclei at the
magic neutron number N=82. These new calculations use a larger model space than
previous shell model studies and an improved residual interaction which is
adjusted to recent spectroscopic data around A=130. Our shell-model results
give a good account of all experimentally known half-lives and -values
for the N=82 r-process waiting point nuclei. Our half-life predictions for the
N=82 nuclei with Z=42--46 agree well with recent estimates based in the
energy-density functional method
Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory
The Pierre Auger Collaboration has reported evidence for anisotropy in the
distribution of arrival directions of the cosmic rays with energies
eV. These show a correlation with the distribution
of nearby extragalactic objects, including an apparent excess around the
direction of Centaurus A. If the particles responsible for these excesses at
are heavy nuclei with charge , the proton component of the
sources should lead to excesses in the same regions at energies . We here
report the lack of anisotropies in these directions at energies above
(for illustrative values of ). If the anisotropies
above are due to nuclei with charge , and under reasonable
assumptions about the acceleration process, these observations imply stringent
constraints on the allowed proton fraction at the lower energies
Generalized Fano lineshapes reveal exceptional points in photonic molecules
The optical behavior of coupled systems, in which the breaking of parity and time-reversal symmetry occurs, is drawing increasing attention to address the physics of the exceptional point singularity, i.e., when the real and imaginary parts of the normal-mode eigenfrequencies coincide. At this stage, fascinating phenomena are predicted, including electromagnetic-induced transparency and phase transitions. To experimentally observe the exceptional points, the near-field coupling to waveguide proposed so far was proved to work only in peculiar cases. Here, we extend the interference detection scheme, which lies at the heart of the Fano lineshape, by introducing generalized Fano lineshapes as a signature of the exceptional point occurrence in resonant-scattering experiments. We investigate photonic molecules and necklace states in disordered media by means of a near-field hyperspectral mapping. Generalized Fano profiles in material science could extend the characterization of composite nanoresonators, semiconductor nanostructures, and plasmonic and metamaterial devices
Advanced functionality for radio analysis in the Offline software framework of the Pierre Auger Observatory
The advent of the Auger Engineering Radio Array (AERA) necessitates the
development of a powerful framework for the analysis of radio measurements of
cosmic ray air showers. As AERA performs "radio-hybrid" measurements of air
shower radio emission in coincidence with the surface particle detectors and
fluorescence telescopes of the Pierre Auger Observatory, the radio analysis
functionality had to be incorporated in the existing hybrid analysis solutions
for fluoresence and surface detector data. This goal has been achieved in a
natural way by extending the existing Auger Offline software framework with
radio functionality. In this article, we lay out the design, highlights and
features of the radio extension implemented in the Auger Offline framework. Its
functionality has achieved a high degree of sophistication and offers advanced
features such as vectorial reconstruction of the electric field, advanced
signal processing algorithms, a transparent and efficient handling of FFTs, a
very detailed simulation of detector effects, and the read-in of multiple data
formats including data from various radio simulation codes. The source code of
this radio functionality can be made available to interested parties on
request.Comment: accepted for publication in NIM A, 13 pages, minor corrections to
author list and references in v
Search for First Harmonic Modulation in the Right Ascension Distribution of Cosmic Rays Detected at the Pierre Auger Observatory
We present the results of searches for dipolar-type anisotropies in different
energy ranges above eV with the surface detector array of
the Pierre Auger Observatory, reporting on both the phase and the amplitude
measurements of the first harmonic modulation in the right-ascension
distribution. Upper limits on the amplitudes are obtained, which provide the
most stringent bounds at present, being below 2% at 99% for EeV
energies. We also compare our results to those of previous experiments as well
as with some theoretical expectations.Comment: 28 pages, 11 figure
Microbiological and chemical monitoring of Marsala base wine obtained by spontaneous fermentation during large-scale production
The present work was undertaken to evaluate the effect of the natural winemaking on
the microbial and chemical composition of Marsala base wine. To this purpose, a
large-scale vinification process of Grillo grape cultivar was monitored from harvesting
to the final product. Total yeasts (TY) showed a rapid increase after must pressing and
reached values almost superimposable to those registered during the conventional
winemakings. Lactic acid bacteria (LAB) were registered at the highest levels
simultaneously to yeast growth at the beginning of the process. Saccharomyces
cerevisiae was the species found at the highest concentrations in all samples
analysed. Several strains (n= 16) was registered at high levels during the alcoholic
fermentation and/or aging of wine; only two of them were detected on the grape
surface. Lactobacillus plantarum was the LAB species most frequently isolated during
the entire vinification process. Ethanol content was approximately 14% (v/v) at the end
of vinification. The value of pH did not greatly vary during the process and the volatile
acidity (VA) was detected at low concentrations during the entire transformation. The
concentration of malic acid rapidly decreased during the AF; on the other hand, lactic
acid showed an irregular trend during the entire process. trans-caffeil tartaric acid was
the most abundant hydroxycinnamoyl tartaric acid and volatile organic compounds
(VOC) were mainly represented by isoamylic alcohol and isobutanol
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