2,803 research outputs found
Study of B -> pi l nu and B -> rho l nu decays and determination of |Vub|
No full textWe present an analysis of exclusive charmless semileptonic B-meson decays based on 377×106 BB̅ pairs recorded with the BABAR detector at the Υ(4S) resonance. We select four event samples corresponding to the decay modes B0→π-l+ν, B+→π0l+ν, B0→ρ-l+ν, and B+→ρ0l+ν and find the measured branching fractions to be consistent with isospin symmetry. Assuming isospin symmetry, we combine the two B→πlν samples, and similarly the two B→ρlν samples, and measure the branching fractions B(B0→π-l+ν)=(1.41±0.05±0.07)×10-4 and B(B0→ρ-l+ν)=(1.75±0.15±0.27)×10-4, where the errors are statistical and systematic. We compare the measured distribution in q2, the momentum transfer squared, with predictions for the form factors from QCD calculations and determine the Cabibbo-Kobayashi-Maskawa matrix element |Vub|. Based on the measured partial branching fraction for B→πlν in the range q2<12 GeV2 and the most recent QCD light-cone sum-rule calculations, we obtain |Vub|=(3.78±0.13-0.40+0.55)×10-3, where the errors refer to the experimental and theoretical uncertainties. From a simultaneous fit to the data over the full q2 range and the FNAL/MILC lattice QCD results, we obtain |Vub|=(2.95±0.31)×10-3 from B→πlν, where the error is the combined experimental and theoretical uncertainty
Design of X-Concentric Braced Steel Frame Systems Using an Equivalent Stiffness in a Modal Elastic Analysis
No full textIn this work, a general method for the design of concentric braced steel frames (CBF) with active tension diagonal bracings, applicable to single- and multi-storey structures, is presented. The method is based on the use of an elastic modal analysis with a response spectrum, which is carried out using an appropriate modified elastic stiffness of diagonal bracings. The reliability of the proposed method is validated through the analysis of significant case studies, making a series of numerical comparisons carrying out time-history non-linear dynamic analysis
Assessment of the effect of seismic sequences on steel X-CBF for industrial buildings
No full textThis work concerns about the study of the effect of the seismic sequences on steel mono-storey industrial buildings equipped with X-CBFs, with the aim to evaluate a code change to adequately consider this issue. Indeed, current technical regulations (CEN, 2004; MIT, 2018) do not take into account this phenomenon, thus the structure are designed only to withstand a single main-shock, without considering the possible accumulation of damage due to the after-shocks. In this work it is instead shown how this effect has to be properly considered and evaluated. First, a mono-storey industrial building is analysed as preliminary case study. Fragility curves are built for both sequences and single main events, thus obtaining an important comparison. Then the study focuses on a single X-CBF, validated through an experimental test from literature. The calibrated system is subjected to both seismic sequences and corresponding mainshocks. Analyses are carried out also by varying brace profiles. The results show a significant influence of the seismic sequences on the increase of the ductility request of the structure. Therefore, with the aim to properly represent the effect of the sequences, it is considered necessary to require a reduction of the available behavior factor, providing a precautionary estimate. This operation wants to give a first preliminary estimate of the increase of the seismic risk only on the seismic vulnerability side of this kind of structures
Survey on non-linear cyclic responses of Unreinforced Masonry buildings by means of commercial finite-element codes
No full textThis work presents a comparison about the nonlinear cyclic response of unreinforced masonry structures obtained by using commercial calculation codes and on the base of the type of modeling approaches currently available. In particular, several elastoplastic modeling methodologies are considered, representative of a good part of the state of the art for this type of construction: mechanical-based concentrated plasticity macro-element (Tremuri), macro-element with diffuse fiber-based plasticity for flexure and concentrated springs for shear (SeismoStruct) and macro-element with phenomenological-based concentrated plasticity (NextFEM Designer). The purpose of the present research is to evaluate the ability of the different codes to represent the proper hysteretic response of masonry structures. To this aim, several experimental tests from literature are analyzed and compared; two different masonry panels, characterized by different resistant mechanisms, and an entire perforated wall have been studied through nonlinear cyclic static analyses. The reported comparison, mainly focused on the numerical cyclic behaviour exhibited by each computer program, is conducted on the basis of the path of the cycles obtained and on the amount of dissipated energy
Problematiche progettuali e proposte di soluzione per controventi in acciaio a diagonale tesa attiva – Parte II: progettazione di sistemi controventati mediante uso di una rigidezza equivalente per l’analisi elastica modale con spettro di risposta
No full textSOMMARIO
Nel presente lavoro e in [1] si approfondiscono alcune problematiche progettuali relative ai controventi in
acciaio a diagonale tesa attiva (detti anche a croce di Sant’Andrea). Dopo aver analizzato il comportamento
di questo tipo di controventi e proposto la costruzione di curve di pushover analitiche trilineari, in questo
secondo lavoro si presenta un metodo generale di progettazione, applicabile sia ad edifici monopiano
industriali che multipiano, dotati di questa tipologia di controvento. Il metodo è basato sull’utilizzo
dell’analisi elastica modale con spettro di risposta, condotta tramite l’utilizzo di una rigidezza elastica
opportunamente modificata. Mediante l’analisi di una serie di casi studio, si dimostra l’affidabilità del
metodo progettuale proposto, effettuando una serie di confronti numerici e validando il metodo con analisi
dinamiche al passo.
ABSTRACT
In this work and in [1] some important issues related to the design of concentric braced steel frames (CBF)
with active tension diagonal bracings are analyzed. In [1] the behaviour of this type of bracing was analyzed
and the construction of a trilinear analytic pushover curve was proposed. In this work a general method for
the design of CBF buildings, applicable to both single and multi-storey structures, is presented. The method
is based on the use of an elastic modal analysis with response spectrum, carried out on models using an
appropriate modified elastic stiffness of diagonal bracings. The reliability of the proposed method is
validated through the analysis of significant case studies, making a series of numerical comparisons by
carrying out time-history dynamic analysis
Problematiche progettuali e proposte di soluzione per controventi in acciaio a diagonale tesa attiva – Parte I: tracciamento analitico delle curve di pushover
No full textSOMMARIO
Nel presente lavoro e in [1] si vanno ad approfondire una serie di problematiche progettuali relative ai
controventi in acciaio a diagonale tesa attiva (detti anche a croce di Sant’Andrea), analizzando sia edifici
monopiano industriali che multipiano.
In questa prima parte si analizza il comportamento di questo tipo di controventi proponendo la costruzione
di un “fuso” di pushover, caratterizzato da due curve analitiche trilineari di capacità definite su un sistema
controventato assoggettato ad una prefissata distribuzione di forze laterali. La bontà di tale proposta
analitica viene evidenziata da una serie di confronti numerici ottenuti con un accurato modello di calcolo,
validato sulla base di risultati sperimentali. La proposta viene estesa ad intere strutture monopiano e
multipiano, evidenziando per i casi studio analizzati un’ottima corrispondenza con i risultati numerici.
ABSTRACT
In this work and in the companion article [1] some important issues related to the design of concentric
braced steel frames (CBF) with active tension diagonal bracings are analyzed by examining single-storey
industrial buildings and multi-storey buildings.
In this first part, the behaviour of this type of bracing is analyzed and the construction of a pushover
“spindle”, characterized by two trilinear analytical capacity curves defined on a CBF system subjected to
prefixed lateral forces distribution, is proposed. The goodness of this analytical proposal is validated by a
series of numerical comparisons obtained through an accurate calculation model, calibrated on the basis of
experimental results. The proposal is then extended to entire single- and multi-storey structures, showing a
good correspondence with the numerical results of the analysed case studies
An updating of the occurrence of canine heartworm disease in northern Italy
No full textA survey was carried out in northern Italy (Veneto and Friuli Venezia Giulia Regions) to assess the extension of canine heartworm disease close to the classic hyperendemic areas of the Po Valley. A filtration test on 275 privately owned dogs showed a mean prevalence of 44%, with a peak of 55% in the Venice province. A high prevalence (17%) of occult filariosis was discovered using a serological test. These values fall within the medium-high range previously reported from other Italian areas. The provinces of Pordenone, Udine, Trieste, Treviso and Belluno, where no cases had been previously reported, were found to be infected. The distribution of the infection did not differ significantly with the dogs' origin or sex. The prevalence seemed to be influenced significantly (p<0.01) by the hosts' age, function and degree of outdoor activity, reflecting the different exposure risks
CN60The experience of dysgeusia in allogenic hematopoietic cell transplantation survivors: A qualitative study
No full textBackground: Taste disorders are one of the most common side effects of treatment in oncology patients and often occur after allogeneic hematopoietic cell transplantation (allo-HCT). Dysgeusia is rarely a life-threatening complication, therefore, in many cases it does not receive close medical attention. Furthermore, information about this disorder is largely based on the clinician’s own experience. However, taste disorders, can impact on the quality of life in survivors of allo-HCT, and compromise their enjoyment of eating, food intake, weight and nutritional status. The number of performed annual transplantations continues to grow annually and the number of older long-term survivors increases. There is little literature that is focused on studies of survivors of allo-HCT with taste disorders. We conducted a qualitative descriptive study to explore experiences of dysgeusia in patients that have undergone of allo-HCT and examined what strategies they used to mitigate it. Methods: Using purposive sampling, survivors of allo-HCT were recruited. Audiotape interviews were conducted until data saturation was achieved. Each interview was transcribed verbatim, and content analyses were performed to extract significant themes and subthemes. Results: Three major themes embracing various aspects of allo-HCT survivors’ experiences were identified: 1) the shape of taste; 2) everything is irritating and it is arduous to eat; 3) finding new strategies to overcome the problems. Together, they highlight the experiences of survivors showing how taste disorders can affect the physical, psychological and social dimensions of a person for the rest of their life. Conclusions: A cumulative burden is the result of dysgeusia and its clinical course reinforced also by related symptoms. Healthcare professionals must focus their attention on the management of these symptoms and offer interventions to safeguard the patient’s social, physical and psychological well-being. Finally, further research is needed to explore the experiences of allo-HTC patients who have taste disorders throughout their cancer journey that introduces a more holistic approach which involves health professionals, caregivers and family members
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