Analysis of rheological and thermo-hygro-mechanical behaviour of stress-laminated timber bridge deck in variable environmental conditions

La madera presenta un comportamiento termo-higromecánico cuando se somete a la acción conjunta de variaciones de temperatura, humedad relativa y carga mecánica. Los tableros tensados de madera presentan pérdidas de fuerza en la barra de tensado debido principalmente a la relajación de la tensión y a la contracción de la madera, aumentando con los cambios de humedad y temperatura de ésta. El objetivo de este estudio fue estudiar el comportamiento reológico de tableros tensados de madera de pino radiata (Pinus radiata D. Don) sometidos a cambios de temperatura y humedad relativa. Un total de 16 probetas fueron previamente tratadas con diferentes tratamientos de preservación, las cuales fueron sometidas a cuatro ciclos de temperatura y humedad relativa en una cámara de clima. La deformación de las probetas y la tensión de las barras de acero fueron medidas. Los resultados mostraron que la variación de la temperatura y de la humedad tiene una fuerte influencia en la variación de la tensión de las barras tensoras. Los retensados minimizaron la pérdida de tensión de las barras. Además, no se observaron evidencias de fluencia termo-higromecánica ni relajación de la tensión de las muestras de puentes tensados en este estudio.Wood material has a thermo-hygromechanical behaviour because its deformation depends on the combined action of temperature, relative humidity and mechanical load variations. Stress-laminated timber bridge deck show a reduction of stress in the tension bars mainly due to the relaxation and shrinkage of wood, increasing with moisture content and temperature changes within the wood. The aim of this research was to study the rheological behavior of stress-laminated timber bridge deck samples under temperature and relative humidity variations. A total of 16 samples were previously treated with four types of preservative treatments, which were subjected to four cycles of temperature and relative humidity in a climate chamber. Wood samples deformation and stress in the steel bars were measured. The results showed a significant stress reduction in the steel bar during the summer season and a significant increase during the winter season. The results also showed significant differences between the deformations of control samples compared to the preservative treated samples for each cycle. However, for interlaminar stress, differences were significant only in the winter season. Moreover, for both deformation and interlaminar stress, no significant differences between cycles three and four were found. Therefore there is no evidence of thermo-hygromechanical creep or relaxation of wood in the conditions considered in this study

123I-FP-CIT SPECT validation of nigro-putaminal MRI tractography in dementia with Lewy bodies

Abstract BACKGROUND: Assessment of nigrostriatal degeneration is a key element to discriminate between dementia with Lewy bodies (DLB) and Alzheimer disease (AD), and it is often evaluated using ioflupane (123I-FP-CIT) single-photon emission computed tomography (SPECT). Given the limited availability of 123I-FP-CIT SPECT, we evaluated if a mask-based approach to nigroputaminal magnetic resonance imaging (MRI) diffusion-weighted tractography could be able to capture microstructural changes reflecting nigroputaminal degeneration in DLB. METHODS: A nigroputaminal bundle mask was delineated on 12 healthy volunteers (HV) and applied to MRI diffusion-weighted data of 18 subjects with DLB, 21 subjects with AD and another group of 12 HV. The correlation between nigroputaminal fractional anisotropy (FA) values and 123I-FP-CIT SPECT findings was investigated. Shapiro-Wilk, ANOVA, ANCOVA, and parametric correlation statistics as well as receiver operating characteristic (ROC) analysis were used. RESULTS: DLB patients showed a higher nigroputaminal FA values compared with both AD and HV-controls groups (p = 0.001 for both comparisons), while no difference was observed between HV-controls and AD groups (p = 0.450); at ROC analysis, the area under the curve for the discriminating DLB and AD subjects was 0.820; FA values correlated with 123I-FP-CIT values (on the left, r = -0.670; on the right, r = -720). No significant differences were observed for the FA of the corticospinal tract across the three groups (p = 0.740). CONCLUSIONS: In DLB, nigroputaminal degeneration could be reliably assessed on MRI diffusion scans using a mask of nigroputaminal bundle trajectory. Nigroputaminal FA in DLB patients correlated with 123I-FP-CIT values data may allow to differentiate these patients from AD patients and HV-controls

Semi-quantification and grading of amyloid PET: A project of the European Alzheimer's Disease Consortium (EADC)

Background amyloid-PET reading has been classically implemented as a binary assessment, although the clinical experience has shown that the number of borderline cases is non negligible not only in epidemiological studies of asymptomatic subjects but also in naturalistic groups of symptomatic patients attending memory clinics. In this work we develop a model to compare and integrate visual reading with two independent semi-quantification methods in order to obtain a tracer-independent multi-parametric evaluation. Methods We retrospectively enrolled three cohorts of cognitively impaired patients submitted to 18F-florbetaben (53 subjects), 18F-flutemetamol (62 subjects), 18F-florbetapir (60 subjects) PET/CT respectively, in 6 European centres belonging to the EADC. The 175 scans were visually classified as positive/negative following approved criteria and further classified with a 5-step grading as negative, mild negative, borderline, mild positive, positive by 5 independent readers, blind to clinical data. Scan quality was also visually assessed and recorded. Semi-quantification was based on two quantifiers: the standardized uptake value (SUVr) and the ELBA method. We used a sigmoid model to relate the grading with the quantifiers. We measured the readers accord and inconsistencies in the visual assessment as well as the relationship between discrepancies on the grading and semi-quantifications. Conclusion It is possible to construct a map between different tracers and different quantification methods without resorting to ad-hoc acquired cases. We used a 5-level visual scale which, together with a mathematical model, delivered cut-offs and transition regions on tracers that are (largely) independent from the population. All fluorinated tracers appeared to have the same contrast and discrimination ability with respect to the negative-to-positive grading. We validated the integration of both visual reading and different quantifiers in a more robust framework thus bridging the gap between a binary and a user-independent continuous scale

Semi-quantification and grading of amyloid PET: A project of the European Alzheimer's Disease Consortium (EADC)

Background amyloid-PET reading has been classically implemented as a binary assessment, although the clinical experience has shown that the number of borderline cases is non negligible not only in epidemiological studies of asymptomatic subjects but also in naturalistic groups of symptomatic patients attending memory clinics. In this work we develop a model to compare and integrate visual reading with two independent semi-quantification methods in order to obtain a tracer-independent multi-parametric evaluation. Methods We retrospectively enrolled three cohorts of cognitively impaired patients submitted to 18F-florbetaben (53 subjects), 18F-flutemetamol (62 subjects), 18F-florbetapir (60 subjects) PET/CT respectively, in 6 European centres belonging to the EADC. The 175 scans were visually classified as positive/negative following approved criteria and further classified with a 5-step grading as negative, mild negative, borderline, mild positive, positive by 5 independent readers, blind to clinical data. Scan quality was also visually assessed and recorded. Semi-quantification was based on two quantifiers: the standardized uptake value (SUVr) and the ELBA method. We used a sigmoid model to relate the grading with the quantifiers. We measured the readers accord and inconsistencies in the visual assessment as well as the relationship between discrepancies on the grading and semi-quantifications. Conclusion It is possible to construct a map between different tracers and different quantification methods without resorting to ad-hoc acquired cases. We used a 5-level visual scale which, together with a mathematical model, delivered cut-offs and transition regions on tracers that are (largely) independent from the population. All fluorinated tracers appeared to have the same contrast and discrimination ability with respect to the negative-to-positive grading. We validated the integration of both visual reading and different quantifiers in a more robust framework thus bridging the gap between a binary and a user-independent continuous scale

O SOLE MIO / Di Capua, Capurro ; Claudio Villa, avec l'Orchestre Ovidio Sarra. USIGNOLO / Concina, Martelli, Castellani ; Claudio Villa, avec l'Orchestre Armando Fragna. CHIESETTA SOLITARIA / Bezzi, Pintaldi ; Claudio Villa, avec l'Orchestre Armando Fragna. ARRIVEDERCI ROMA / Rascel, Garinei, Giovannini ; Claudio Villa, avec l'Orchestre Edoardo del Pino. PERDOMANI / Sarra, Morbelli ; Claudio Villa, avec l'Orchestre Armando Fragna. MALINCONICO AUTUMNO / Rendine, de Crescenzo ; Claudio Villa, avec l'Orchestre Armando Fragna. CORDE DELLA MIA CHITARRA / Ruccione, Cavalière, Fiorelli ; Claudio Villa, avec l'Orchestre Angelini. LA PIU BELLA CANZONE DEL MONDO / Filippini, Mari ; Claudio Villa, avec l'Orchestre Angelini

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Prosafe: a european endeavor to improve quality of critical care medicine in seven countries

BACKGROUND: long-lasting shared research databases are an important source of epidemiological information and can promote comparison between different healthcare services. Here we present ProsaFe, an advanced international research network in intensive care medicine, with the focus on assessing and improving the quality of care. the project involved 343 icUs in seven countries. all patients admitted to the icU were eligible for data collection. MetHoDs: the ProsaFe network collected data using the same electronic case report form translated into the corresponding languages. a complex, multidimensional validation system was implemented to ensure maximum data quality. individual and aggregate reports by country, region, and icU type were prepared annually. a web-based data-sharing system allowed participants to autonomously perform different analyses on both own data and the entire database. RESULTS: The final analysis was restricted to 262 general ICUs and 432,223 adult patients, mostly admitted to Italian units, where a research network had been active since 1991. organization of critical care medicine in the seven countries was relatively similar, in terms of staffing, case mix and procedures, suggesting a common understanding of the role of critical care medicine. conversely, icU equipment differed, and patient outcomes showed wide variations among countries. coNclUsioNs: ProsaFe is a permanent, stable, open access, multilingual database for clinical benchmarking, icU self-evaluation and research within and across countries, which offers a unique opportunity to improve the quality of critical care. its entry into routine clinical practice on a voluntary basis is testimony to the success and viability of the endeavor