127 research outputs found
La Stima dei Moduli Elastici delle Murature Secondo le Norme Tecniche: il Confronto con la Sperimentazione
Nel presente lavoro viene proposto uno studio sperimentale per la caratterizzazione meccanica di diverse tipologie di muratura. Vengono in particolare valutati i moduli elastici longitudinali e tangenziali che come Ăš noto condizionano la risposta di sistemi murari sotto carichi laterali. I valori sperimentali sono confrontati con quelli stimabili per mezzo dei modelli proposti dalle normative tecniche italiana (DM 14/01/2008) e europea (Eurocodice 6). Lo studio prende spunto dalla questio posta dalla norma americana (MSJC 2008) che, pur proponendo lâuso di tali modelli, riconosce la poca sperimentazione eseguita a supporto della loro validazione. La campagna sperimentale ha incluso prove di compressione sui componenti (malte e blocchi), prove di compressione diagonale e prove di compressione ordinaria (in direzione ortogonale ai letti di malta) su porzioni di muratura. I risultati conseguiti hanno consentito la valutazione diretta dei moduli elastici e successivamente di ottenere le grandezze meccaniche necessarie per lâutilizzo dei succitati modelli normativi
Risk factors for esophago-jejunal anastomosis leakage after total gastrectomy for cancer. A multicenter retrospective study of the Italian research group for gastric cancer
Background: Many Eastern reports attempted to identify predictive variables for esophago-jejunal anastomosis leakage (EJAL) after total gastrectomy for cancer. There are no definitive answers about reliable risk factors for EJAL. This retrospective study shows the largest Western series focused on this topic.Methods: This is a multicenter retrospective study analyzing patients' datasets collected by 18 Italian referral Centres of the Italian Research Group for Gastric Cancer (GIRCG) from 2000 to 2018. The inclusion criteria were pathological diagnosis of gastric and esophageal (Siewert III) carcinoma requiring total gastrectomy. The primary end point of risk analysis was the occurrence of EJAL; secondary end points were post-operative (30-day) morbidity and mortality, length of stay (LoS), and survival.Results: Data of 1750 patients submitted to total gastrectomy were collected. EJAL developed in 116 (6.6%) patients and represented the 26.3% of all the 441 observed post-operative surgical complications. EJAL diagnosis was followed by a reoperation in 39 (33.6%) patients and by an endoscopic/radiological procedure in 30 cases (25.9%). In 47 patients (40.5%) EJAL was managed with conservative approach. Post-operative LoS and mortality were significantly higher after EJAL occurrence (27 days versus 12 days and 8.6% versus 1.6%, respectively). At risk analysis, comorbidities (particularly, if respiratory), minimally invasive surgery, extended lymphadenectomy, and anastomotic technique resulted significant predictive factors for EJAL. EJAL did not significantly affect survival.Conclusions: These results were consistent with Asian experiences: the frequency of EJAL and its higher rate observed in patients with comorbidities or after minimally invasive approach were confirmed. (C) 2020 Elsevier Ltd, BASO similar to The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved
Experimental testing of two novel stress sensors for SHM of masonry structures
The paper presents an experimental study on the performance of two types of
stress sensor for their possible use in structural health monitoring (SHM) of masonry
constructions. Ceramic piezoelectric sensors and capacitive sensors were installed in mortar
bed-joints of two series of masonry specimens made of calcarenite stones and clay bricks. The
specimens were tested under uniaxial compression, assessing the effectiveness of the sensors in
recording the stress state variation in terms of vertical stresses within different types of
masonry. Experimental results show that, although both the ceramic and capacitive sensors
were initially designed to be embedded in concrete elements, their application in mortar joints
ensures a good agreement with records by standard measurement devices. Results also
demonstrate the possibility to extend the application of these devices to existing masonry
structures, where SHM becomes a challenging issu
Pulsed Bessel beam-induced microchannels on a diamond surface for versatile microfluidic and sensing applications
We present a laser machining method based on the use of pulsed Bessel beams to create, by single pass transverse writing, three-dimensional trench-like microstructures on a synthetic monocrystalline diamond substrate. By tuning the laser pulse energy and the writing speed, it is possible to control the features of the surface trenches obtained and to optimize the resulting high aspect-ratio and low roughness microstructures. This work confirms the potentialities of quasi-stationary beams in ultra-fast laser inscription technology. In particular the presented results show the possibility to fabricate deep and precise microfluidic channels on biocompatible diamond substrates, offering a great potential for biomedical sensing applications
Air Pollution, Aeroallergens, and Emergency Room Visits for Acute Respiratory Diseases and Gastroenteric Disorders among Young Children in Six Italian Cities
Past studies reported evidence of associations between air pollution and respiratory symptoms and morbility for children. Few studies examined associations between air pollution and emergency room (ER) visits for wheezing, and even fewer for gastroenteric illness. We conducted a multicity analysis of the relationship between air pollution and ER visits for wheezing and gastroenteric disorders in children 0-2 years of age.BACKGROUND: Past studies reported evidence of associations between air pollution and respiratory symptoms and morbidity for children. Few studies examined associations between air pollution and emergency room (ER) visits for wheezing, and even fewer for gastroenteric illness. We conducted a multicity analysis of the relationship between air pollution and ER visits for wheezing and gastroenteric disorder in children 0-2 years of age. METHODS: We obtained ER visit records for wheezing and gastroenteric disorder from six Italian cities. A cityspecific case-crossover analysis was applied to estimate effects of particulate matter (PM), nitrogen dioxide, sulfur dioxide, ozone, and carbon monoxide, adjusting for immediate and delayed effects of temperature. Lagged effects of air pollutants up to 6 prior days were examined. The cityspecific results were combined using a random-effect meta-analysis. RESULTS: CO and SO2 were most strongly associated with wheezing, with a 2.7% increase [95% confidence interval (CI), 0.5-4.9] for a 1.04 \u3bcg/m3 increase in 7day average CO and a 3.4% (95% CI, 1.5-5.3) increase for an 8.0 \u3bcg/m3 increase in SO2. Positive associations were also found for PM with aerodynamic diameter 64 10 \u3bcg and NO2. We found a significant association between the 3day moving average CO and gastroenteric disorders [3.8% increase (95% CI, 1.0-6.8)]. When data were stratified by season, the associations were stronger in summer for wheezing and in winter for gastroenteric disorders. CONCLUSION: Air pollution is associated with triggering of wheezing and gastroenteric disorders in children 0-2 years of age; more work is needed to understand the mechanisms to help prevent wheezing in children
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
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
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
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