375 research outputs found

    Corrosion damage and periodic inspections on pressure devices and lifting equipments

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    This paper deals with requirements for service safety conditions of pressure devices and lifting equipments,according to the European and Italian Standards. Periodic controls and inspections are necessary to checkcorrosion damage and determine residual life, as showed for some significant case histories. As concern aspressure device, hydrogen induced cracking phenomena in steel walls of a demister, utilized to enhance the liquiddroplets removal in a vapor stream, were detected by ultrasound measurements. The measured defect sizeswere put in comparison with the required limits to verify if this device can be maintained in service. About liftingequipments, two different corrosion mechanisms were examined by detecting defects and measuring residualplate thickness: crevice, due to aggressive environment, at the interstitial of steel plates overlap in a welded andbolted joint of a gantry crane; lastly, crevice and corrosion fatigue of steel rail and plate in a double girder shipyardbridge crane, that was exposed for some decades to the daily aggressive action of direct solar radiation and seasalt, detrimental for the coating layer. In these two cases both defects size and plates thickness were consideredwith the aim of indicating treatments and restoration procedures of damaged components

    Interior Regularity Estimates in High Conductivity Homogenization and Application

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    In this paper, uniform pointwise regularity estimates for the solutions of conductivity equations are obtained in a unit conductivity medium reinforced by a epsilon-periodic lattice of highly conducting thin rods. The estimates are derived only at a distance epsilon^{1+tau} (for some tau>0) away from the fibres. This distance constraint is rather sharp since the gradients of the solutions are shown to be unbounded locally in L^p as soon as p>2. One key ingredient is the derivation in dimension two of regularity estimates to the solutions of the equations deduced from a Fourier series expansion with respect to the fibres direction, and weighted by the high-contrast conductivity. The dependence on powers of epsilon of these two-dimensional estimates is shown to be sharp. The initial motivation for this work comes from imaging, and enhanced resolution phenomena observed experimentally in the presence of micro-structures. We use these regularity estimates to characterize the signature of low volume fraction heterogeneities in the fibred reinforced medium assuming that the heterogeneities stay at a distance epsilon^{1+tau} away from the fibres

    Measuring changes in Schlemm’s canal and trabecular meshwork in different accommodation states in myopia children: an observational study

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    Abstract Purpose: Studies were designed to evaluate changes in the size of the Schlemm's Canal (SC) and trabecular meshwork(TM) during accommodation stimuli and cycloplegia states in myopic children. Methods: 34 children were enrolled. A -6D accommodation stimulus was achieved by looking at an optotype through a mirror. Cycloplegia state was induced with 1% tropicamide. Two states were confirmed by measuring the central lens thickness(CLT), the anterior chamber depth and the pupil diameter. The size of the Schlemm's Canal (SC) and Trabecular Meshwork(TM) was measured using swept-source optical coherence tomography. And the associations between the change of the SC and the CLT were analyzed. Results: When compared with the relaxation state, under -6D accommodation stimuli, the size of SC increased significantly: the SC area (SCA) amplified from 6371±2517μm2 to 7824±2727 μm2; the SC length (SCL) from 249±10 μm to 295±12 μm, and SC width (SCW) from 27±9 μm to 31±8 μm. Under cycloplegia state, the SCA reduced to 5009±2028 μm2; the SCL to 212±μm and the SCW to 22±5 μm. In addition, the changed areas of SCA (r=0. 35; P=0.0007), SCL (r=0. 251; P=0.0172), and SCW (r=0. 253; P=0.016) were significantly correlated with the change in CLT. However, the size of TM did not change substantially when compared with the relaxation state. Only the TM length (TML) increased from 562±45μm to 587±47μm after -6D accommodation stimulus. Conclusion: SC size enlarges after -6D accommodation stimuli and shrinks under cycloplegia. However, for TM, only the TM length increase under accommodation stimulus state. KEYWORDS: Schlemm’s Canal, Trabecular Meshwork, accommodatio

    The relationship between nurse managers' leadership style and patients' perception of the quality of the care provided by nurses: Cross sectional survey

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    Background:  In healthcare systems, human resources play a strategic role that has a significant impact on the whole caring process. When the wellbeing of professionals is low their performance decreases, counterproductive work behaviours may became more likely, and as a result the quality of care is compromised. Studies have shown that leadership style is particularly relevant in relation to the quality of work environments in healthcare organizations. Objective:  The main purpose of this study is to test a model that investigates the relationships between nurse managers’ leadership style and patients’ perception of the quality of the care provided by the nurses, through the mediation of the quality of the working environment (in terms of burnout, interpersonal strain and counterproductive work behaviour). Design:  A multi-centre cross-sectional study was conducted. Setting:  The study was conducted in five hospitals located two in the north, two in the centre and one in the south of Italy. Participants:  Participants were 479 registered nurses (working as staff nurses, while head nurses and nurse managers were excluded) and 829 patients aged 18 years or older, able to read and write Italian and hospitalized for at least 3 days. Severely ill or mentally disabled patients who were not able to fill in the questionnaire were excluded. Methods:  The data were collected through two different questionnaires, one for the nurses and one for the patients. A multilevel analysis was conducted to examine the hypothesized model. Results:  Results confirmed the hypothesis that, when nurses were satisfied with leadership, they felt less burned-out and strained in interpersonal relationships, they engaged less in misbehaviour, and, in turn, patients were more satisfied with the quality of the care provided by the nurses. Conclusions:  The results of this study showed that the characteristics of the organizational context, the leadership, and the behaviours of nurses, influenced patients’ perceptions of nurses’ care. Therefore, managers of healthcare services should take these results into account seriously in order to improve the quality of care provided to patients

    Searches for lepton-flavour-violating decays of the Higgs boson into eτ and μτ in \sqrt{s} = 13 TeV pp collisions with the ATLAS detector

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    Abstract This paper presents direct searches for lepton flavour violation in Higgs boson decays, H → eτ and H → μτ, performed using data collected with the ATLAS detector at the LHC. The searches are based on a data sample of proton-proton collisions at a centre-of-mass energy s s \sqrt{s} = 13 TeV, corresponding to an integrated luminosity of 138 fb−1. Leptonic (τ → ℓνℓντ) and hadronic (τ → hadrons ντ) decays of the τ-lepton are considered. Two background estimation techniques are employed: the MC-template method, based on data-corrected simulation samples, and the Symmetry method, based on exploiting the symmetry between electrons and muons in the Standard Model backgrounds. No significant excess of events is observed and the results are interpreted as upper limits on lepton-flavour-violating branching ratios of the Higgs boson. The observed (expected) upper limits set on the branching ratios at 95% confidence level, B B \mathcal{B} (H → eτ) < 0.20% (0.12%) and B B \mathcal{B} (H → μτ ) < 0.18% (0.09%), are obtained with the MC-template method from a simultaneous measurement of potential H → eτ and H → μτ signals. The best-fit branching ratio difference, B B \mathcal{B} (H → μτ) → B B \mathcal{B} (H → eτ), measured with the Symmetry method in the channel where the τ-lepton decays to leptons, is (0.25 ± 0.10)%, compatible with a value of zero within 2.5σ

    Studies of new Higgs boson interactions through nonresonant HH production in the b¯bγγ fnal state in pp collisions at √s = 13 TeV with the ATLAS detector