229 research outputs found
Improving predictive power of physically based rainfall-induced shallow landslide models: a probabilistic approach
Distributed models to forecast the spatial and temporal occurrence of
rainfall-induced shallow landslides are based on deterministic laws. These
models extend spatially the static stability models adopted in geotechnical
engineering, and adopt an infinite-slope geometry to balance the resisting and
the driving forces acting on the sliding mass. An infiltration model is used to
determine how rainfall changes pore-water conditions, modulating the local
stability/instability conditions. A problem with the operation of the existing
models lays in the difficulty in obtaining accurate values for the several
variables that describe the material properties of the slopes. The problem is
particularly severe when the models are applied over large areas, for which
sufficient information on the geotechnical and hydrological conditions of the
slopes is not generally available. To help solve the problem, we propose a
probabilistic Monte Carlo approach to the distributed modeling of
rainfall-induced shallow landslides. For the purpose, we have modified the
Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability
Analysis (TRIGRS) code. The new code (TRIGRS-P) adopts a probabilistic approach
to compute, on a cell-by-cell basis, transient pore-pressure changes and
related changes in the factor of safety due to rainfall infiltration.
Infiltration is modeled using analytical solutions of partial differential
equations describing one-dimensional vertical flow in isotropic, homogeneous
materials. Both saturated and unsaturated soil conditions can be considered.
TRIGRS-P copes with the natural variability inherent to the mechanical and
hydrological properties of the slope materials by allowing values of the TRIGRS
model input parameters to be sampled randomly from a given probability
distribution. [..]Comment: 25 pages, 14 figures, 9 tables. Revised version; accepted for
publication in Geoscientific Model Development on 13 February 201
Anisakis sensitization in different population groups and public health impact. A systematic review
Anisakis simplex spp. sensitization rates have increased worldwide, with a significant impact on health-care systems. To date, no clear-cut diagnostic criteria and laboratory algorithm have been established, so anisakiasis still represents an under-reported health problem whose clinical manifestations, when present, mimic the much more common allergic and digestive disorders. Aim of the study was to systematically review the available literature on the prevalence of sensitization against Anisakis in the general population and in specific population groups, taking into account the impact of the different available diagnostic techniques on the epidemiological data. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, relevant papers reporting Anisakis sensitization epidemiological data were found covering a period ranging from 1996 to February 2017. Overall, 41 studies comprising 31,701 participants from eleven countries were included in the qualitative synthesis. General asymptomatic population resulted sensitized to Anisakis in 0.4 to 27.4% of cases detected by means of indirect ELISA or ImmunoCAP specific IgE detection, and between 6.6% and 19.6% of the samples by Skin prick test (SPT). Occupationally exposed workers (fishermen, fishmongers and workers of fish-processing industries) documented specific IgE between 11.7% and 50% of cases, whereas SPT positivity ranged between 8% and 46.4%. Symptomatic allergic patients to any kind of allergen were found to be positive to Anisakis specific IgE detection between 0.0% (in children with mastocytosis) to 81.3% (among adults with shellfish allergy). Results highlighted that hypersensitivity prevalence estimates varied widely according to geographical area, characteristics of the population studied, diagnostic criteria and laboratory assays. Further studies are needed to overcome the documented misdiagnosis by improving the diagnostic approach and, consequently, providing more affordable estimates in order to address public health interventions on populations at high risk of exposure to Anisakis and to tailor health services related to specific groups
Methodological issues in a cross-sectional survey on cervical cancer screening using telephone interviews in Sicily (Italy): a SWOT analysis
Objective: A cross-sectional study on knowledge, perceptions, and adherence to cervical cancer screening was conducted using telephone interviews of Sicilian women that were performed in 2016. This study aimed to identify areas that need to be addressed to improve the validity of data collection and to minimize possible biases. Methods: We performed a qualitative study through SWOT analysis, which is a multidimensional method based on evaluation of Strengths (S), Weaknesses (W), Opportunities (O), and Threats (T) of the research project. The contents of the SWOT forms underwent categorical, inductive, and deductive data analysis using the long table analysis method. Results: The full availability of an updated address and phone number list was the main organizational aspect to be addressed. Socio-cultural context played a major role for understanding the questions and for acceptability of the topics. In some cases, a family member was a facilitating element, while in others, the family member hindered the interviews. Active involvement of general practitioners was considered essential for success of the interviews. Conclusions: When performing a cross-sectional survey, organizational aspects and active involvement of general practitioners are crucial in the enrolment phase, regardless of the socio-cultural context
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
Megaíleo chagásico: Descrição de um caso
É apresentado um caso de megaíleo de natureza chagásica. O paciente, portador da Doença de Chagas, branco com 41 anos, apresentava história de 3 anos de episódios de eólicas abdominais, distensão e diarréia, que foram se tornando mais intensas e mais freqüentes. Fora das crises, apresentava-se assintomático. O diagnóstico de megaíleo foi estabelecido por meio do estudo radiológico contrastado do intestino delgado. O estudo histológico realizado em fragmento obtido à intervenção cirúrgica mostrou diminuição do número de células ganglionares dos plexos mientéricos
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