177,281 research outputs found
DMT-based seismic liquefaction assessment accounting for the fines content effect: a case study in Emilia-Romagna, Italy
No full textSimplified methods for seismic liquefaction assessment based on the flat dilatometer test (DMT), in which the liquefaction triggering curve is defined based on the horizontal stress index (KD), have been proposed over the years. One major drawback of the existing methods, valid for clean sand, is the lack of a correction factor for the fines content. An updating of the empirical relationship CRR-KD proposed by Chiaradonna and Monaco (2022) to incorporate the effects of the fines content is currently under development and validation. This paper illustrates the results obtained from application of the new method at the site of San Carlo – Terre del Reno (Ferrara) located in the Emilia-Romagna plain (Italy), where widespread liquefaction occurred in the 2012 seismic sequence. A comprehensive site characterization from previous insitu
and laboratory tests carried out by various research groups is available for the sand, silty sand and sandy silt deposits in the San Carlo area. The performance of the new CRR-KD curve accounting for the fines content effect is compared with that obtained by adopting the “clean sand” curves proposed by Chiaradonna and Monaco (2022), as well as with that obtained by using the CPT-based method by Boulanger and Idriss (2014). Even though verified only for specific Italian soils in this area and requiring further field validation, the proposed approach appears as promising to improve the DMT-based
liquefaction assessment in silty sands
Partitioning of bronchopulmonary carcinoids in two different prognostic categories by Ki-67 score
No full textIntroduction: Histological distinction between typical and atypical bronchopulmonary car- cinoids is based on mitotic activity and necrosis. Regardless of these two parameters, outcome after surgery is often unpredictable. In this study the prognostic value of different clinico-pathological factors was retrospectively analyzed in a large series of patients with bronchopulmonary carcinoid. Materials and Methods: The long-term post-surgical out- come of 106 radically treated patients affected by bronchopulmonary carcinoid from two Italian centers was correlated with tumor characteristics assessed by combining conven- tional histology with a panel of immunohistochemical markers of neuroendocrine differen- tiation (chromogranin-A, NSE) and proliferation activity (Ki-67 score). Results: Carcinoids were assessed as typical (TC = 75; 70.8%) and atypical (AC = 31; 29.2%). Mean follow-up was 8.3 years (range: 0-20; median: 8.0). All cases expressed neuroendocrine markers. At univariate analysis, tumor recurrence [14/75 TC (18.7%), 15/31 AC (48.4%)] correlated with carcinoid histotype (P = 0.003), tumor size (P = 0.012), mitotic index (P = 0.044), Ki-67 score (P < 0.0001), and synchronous node metastasis (P = 0.037). Of these, Cox multivari- ate analysis confirmed only Ki-67 score as independent predictor of disease recurrence (P = 0.009). The best cut-off for Ki-67 score (calculated by ROC curves) discriminating recurrent vs non-recurrent disease was 4% (sensitivity 79.3%; specificity 83.8%; area under the curve 0.85). By stratifying patients according to this cut-off, a significantly dif- ferent disease-free survival was found (log-rank test P < 0.0001). Conclusion: Ki-67 score accurately separates bronchopulmonary carcinoids in two well-distinct histo-prognostic categories. Ki-67 score predicts the patients outcome better than mitotic count, histotype, and tumor stage and it is therefore helpful in establishing the appropriate follow-up. © 2011 Grimaldi, Muser, Beltrami, Machin, Morelli, Pizzolitto, Talmassons, Marciello, Colao, Monaco, Monaco and Faggiano
SDMT-based Analysis of the Liquefaction Phenomena Induced by the April 6, 2009 Earthquake at Ponte Rasarolo, L'Aquila (Italy)
No full textThis paper analyzes the liquefaction phenomena induced by the April 6, 2009 L'Aquila earthquake (Italy) at the site of Ponte Rasarolo, L'Aquila, located in the epicentral area. The site was investigated by seismic dilatometer tests (SDMT). The SDMT results were used to perform liquefaction analyses by simplified methods which derive the cyclic resistance ratio CRR from the shear wave velocity Vs (Andrus & Stokoe 2000, Kayen et al. 2013) and from the horizontal stress index Kd (Monaco et al. 2005, Tsai et al. 2009, Robertson 2012). The cyclic stress ratio CSR was estimated based on data from strong motion recordings in the area. The results of the liquefaction analyses, both based on Vs and on Kd, confirmed the occurrence of liquefaction in a loose sand layer at about 3 to 4.5 m depth
Presentazione
No full textNuovi approcci ascrivibili all’ambito dei visual studies sembrano avere soppiantato quelli della storia dell’arte, che resta invece strumento fondamentale anche per indagare tematiche più trasversali, come l’arcano rapporto
che lega l’immagine e la parola. In questa prospettiva, la storia dell’arte può
liberarsi dai suoi vincoli tradizionali e aprirsi all’esplorazione di altri domini culturali, da quello letterario a quello filosofico, per analizzare le immagini “latenti”, ossia le traduzioni verbali di oggetti figurativi o la sublimazione in termini
letterari e poetici di opere visuali già prodotte. I contributi contenuti in questo
volume tentano perciò di indagare, da diversi punti di vista, come i meccanismi
propri del visivo possano influenzare o determinare le forme verbali, ma anche
i modi in cui queste ultime riescono talvolta ad accostarsi e tradurre il contenuto ineffabile delle immagini artistiche
Numerical analysis of the effects of PBO-FRCM confinement on RC columns
No full textThis paper presents a finite element (FE) analysis on the behavior of reinforced concrete (RC) squared and rectangular columns strengthened by PBO-FRCM, under axial force and bending moment. The modeling technique adopted for the compressive behavior of confined concrete is previously validated developing FE models for specimens of plain concrete wrapped by PBO-FRCM and comparing the numerical results with those obtained by experimental tests on squared and rectangular confined columns. Then, the model of the RC element is developed reproducing the load condition of columns in a MRF loaded by horizontal forces with constant axial load applied to the pillar during the analysis. The numerical model is validated against experimental results obtained by the authors in a previous study
DMT-based liquefaction triggering procedure accounting for the fines content effect
No full textThe application of semi-empirical charts based on in-situ testing results represents the first step in the earthquake-induced soil liquefaction assessment. Among them, the CPT-based charts have been largely developed in the last decades, especially after the 2010–2011 Canterbury earthquakes in New Zealand, while the main drawback of the existing approach based on DMT is related to the lack of a correction factor for the fines content. In this regard, this study proposes a new empirical relationship between the cyclic resistance ratio and the horizontal stress index where the effects of the fines content are incorporated. The new method is calibrated on specific sites located in the Emilia-Romagna plain (Italy), where an extensive soil characterization from in-situ and laboratory tests was available for the silty sand and sandy silt deposits affected by liquefaction after the 2012 Emilia earthquake. The performance of the new curve accounting for the fines content effect is compared with that obtained by adopting the “clean sand” curves proposed in the past, as well as with that obtained by using the most recent CPT-based method. Even though verified only for specific Italian soils and requiring further field validation, the proposed approach appears as promising to improve the DMT-based liquefaction assessment in silty sands
Performance capability testing of a slab track system
No full textThe permanent way being laid for the urban rail project "Metropolitana Bari Centrale - Quartiere San Paolo" in Bari, Italy, is of the Margaritelli slab track type, whereby prefabricated unstressed reinforced concrete slabs are laid unconnected on elastic matting over a cement layer. To analyse the performance capability of this permanent way type, extended-time threshold testing was carried out in the laboratory. The article describes the tests carried out and the results obtained
SDMT-based Analysis of the Liquefaction Phenomena Induced by the April 6, 2009 Earthquake at Ponte Rasarolo, L'Aquila (Italy)
No full textThis paper analyzes the liquefaction phenomena induced by the April 6, 2009 L'Aquila earthquake (Italy) at the site of Ponte Rasarolo, L'Aquila, located in the epicentral area. The site was investigated by seismic dilatometer tests (SDMT). The SDMT results were used to perform liquefaction
analyses by simplified methods which derive the cyclic resistance ratio CRR from the shear wave velocity VS (Andrus & Stokoe 2000, Kayen et al. 2013) and from the horizontal stress index KD (Monaco et al. 2005, Tsai et al. 2009, Robertson 2012). The cyclic stress ratio CSR was estimated based on data from strong motion recordings in the area. The results of the liquefaction analyses, both based on VS and on KD, confirmed the
occurrence of liquefaction in a loose sand layer at about 3 to 4.5 m depth
Chordal Loewner Equation
No full textThe aim of this survey paper is to present a complete direct proof of a well celebrated cornerstone result of Loewner Theory, originally due to Kufarev et al. [16]. It states that the family of the hydrodynamically normalized conformal self-maps of the upper-half plane onto the complement of a gradually erased slit satisfies, under a suitable parametrization, the chordal Loewner differential equation. The proof is based solely on basic theorems of Geometric Function Theory combined with some elementary topological facts, and it does not require any advanced technique
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