330 research outputs found
Nanoantennas for visible and infrared radiation
Nanoantennas for visible and infrared radiation can strongly enhance the
interaction of light with nanoscale matter by their ability to efficiently link
propagating and spatially localized optical fields. This ability unlocks an
enormous potential for applications ranging from nanoscale optical microscopy
and spectroscopy over solar energy conversion, integrated optical
nanocircuitry, opto-electronics and density-ofstates engineering to
ultra-sensing as well as enhancement of optical nonlinearities. Here we review
the current understanding of optical antennas based on the background of both
well-developed radiowave antenna engineering and the emerging field of
plasmonics. In particular, we address the plasmonic behavior that emerges due
to the very high optical frequencies involved and the limitations in the choice
of antenna materials and geometrical parameters imposed by nanofabrication.
Finally, we give a brief account of the current status of the field and the
major established and emerging lines of investigation in this vivid area of
research.Comment: Review article with 76 pages, 21 figure
Defective Awakening Response to Nocturnal Hypoglycemia in Patients with Type 1 Diabetes Mellitus
BACKGROUND: Nocturnal hypoglycemia frequently occurs in patients with type 1 diabetes mellitus (T1DM). It can be fatal and is believed to promote the development of the hypoglycemia-unawareness syndrome. Whether hypoglycemia normally provokes awakening from sleep in individuals who do not have diabetes, and whether this awakening response is impaired in T1DM patients, is unknown. METHODS AND FINDINGS: We tested two groups of 16 T1DM patients and 16 healthy control participants, respectively, with comparable distributions of gender, age, and body mass index. In one night, a linear fall in plasma glucose to nadir levels of 2.2 mmol/l was induced by infusing insulin over a 1-h period starting as soon as polysomnographic recordings indicated that stage 2 sleep had been reached. In another night (control), euglycemia was maintained. Only one of the 16 T1DM patients, as compared to ten healthy control participants, awakened upon hypoglycemia (p = 0.001). In the control nights, none of the study participants in either of the two groups awakened during the corresponding time. Awakening during hypoglycemia was associated with increased hormonal counterregulation. In all the study participants (from both groups) who woke up, and in five of the study participants who did not awaken (three T1DM patients and two healthy control participants), plasma epinephrine concentration increased with hypoglycemia by at least 100% (p < 0.001). A temporal pattern was revealed such that increases in epinephrine in all participants who awakened started always before polysomnographic signs of wakefulness (mean ± standard error of the mean: 7.5 ± 1.6 min). CONCLUSIONS: A fall in plasma glucose to 2.2 mmol/l provokes an awakening response in most healthy control participants, but this response is impaired in T1DM patients. The counterregulatory increase in plasma epinephrine that we observed to precede awakening suggests that awakening forms part of a central nervous system response launched in parallel with hormonal counterregulation. Failure to awaken increases the risk for T1DM patients to suffer prolonged and potentially fatal hypoglycemia
Low-lying quadrupole collective states of the light and medium Xenon isotopes
Collective low lying levels of light and medium Xenon isotopes are deduced
from the Generalized Bohr Hamiltonian (GBH). The microscopic seven functions
entering into the GBH are built from a deformed mean field of the Woods-Saxon
type. Theoretical spectra are found to be close to the ones of the experimental
data taking into account that the calculations are completely microscopic, that
is to say, without any fitting of parameters.Comment: 8 pages, 4 figures, 1 tabl
Managing quality of cost information in clinical costing:evidence across seven countries
Purpose: The purpose is to assess the impact of clinical costing approaches on the quality of cost information in seven countries (Denmark, England, France, Germany, Ireland, the Netherlands and Portugal). Design/methodology/approach: Costing practices in seven countries were analysed via questionnaires, interviews and relevant published material. Findings: Although clinical costing is intended to support a similar range of purposes, countries display considerable diversity in their approaches to costing in terms of the level of detail contained in regulatory guidance and the percentage of providers subject to such guidance for tariff setting. Guidance in all countries involves a mix of costing methods. Research limitations/implications: The authors propose a two-dimensional Materiality and Quality Score (2D MAQS) of costing systems that can support the complex trade-offs in managing the quality of cost information at both policy and provider level, and between financial and clinical concerns. Originality/value: The authors explore the trade-offs between different dimensions of the quality (accuracy, decision relevance and standardization) and the cost of collecting and analysing cost information for disparate purposes
Discovery of palladium, antimony, tellurium, iodine, and xenon isotopes
Currently, thirty-eight palladium, thirty-eight antimony, thirty-nine
tellurium, thirty-eight iodine, and forty xenon isotopes have been observed and
the discovery of these isotopes is discussed here. For each isotope a brief
synopsis of the first refereed publication, including the production and
identification method, is presented.Comment: to be published in At. Data Nucl. Data Table
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
Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter
Data collected by the Pierre Auger Observatory through 31 August 2007 showed
evidence for anisotropy in the arrival directions of cosmic rays above the
Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{eV}. The
anisotropy was measured by the fraction of arrival directions that are less
than from the position of an active galactic nucleus within 75 Mpc
(using the V\'eron-Cetty and V\'eron catalog). An updated
measurement of this fraction is reported here using the arrival directions of
cosmic rays recorded above the same energy threshold through 31 December 2009.
The number of arrival directions has increased from 27 to 69, allowing a more
precise measurement. The correlating fraction is , compared
with expected for isotropic cosmic rays. This is down from the early
estimate of . The enlarged set of arrival directions is
examined also in relation to other populations of nearby extragalactic objects:
galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in
hard X-rays by the Swift Burst Alert Telescope. A celestial region around the
position of the radiogalaxy Cen A has the largest excess of arrival directions
relative to isotropic expectations. The 2-point autocorrelation function is
shown for the enlarged set of arrival directions and compared to the isotropic
expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201
The Fluorescence Detector of the Pierre Auger Observatory
The Pierre Auger Observatory is a hybrid detector for ultra-high energy
cosmic rays. It combines a surface array to measure secondary particles at
ground level together with a fluorescence detector to measure the development
of air showers in the atmosphere above the array. The fluorescence detector
comprises 24 large telescopes specialized for measuring the nitrogen
fluorescence caused by charged particles of cosmic ray air showers. In this
paper we describe the components of the fluorescence detector including its
optical system, the design of the camera, the electronics, and the systems for
relative and absolute calibration. We also discuss the operation and the
monitoring of the detector. Finally, we evaluate the detector performance and
precision of shower reconstructions.Comment: 53 pages. Submitted to Nuclear Instruments and Methods in Physics
Research Section
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
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