34 research outputs found
Le pitture della cripta del Gonfalone a Tricase (Lecce): problematiche storico-artistiche e contributo alla identificazione dei pigmenti attraverso FRX
Insight in cognitive impairment assessed with the Cognitive Assessment Interview in a large sample of patients with schizophrenia
The Cognitive Assessment Interview (CAI) is an interview-based scale measuring cognitive impairment and its impact on functioning in subjects with schizophrenia (SCZ). The present study aimed at assessing, in a large sample of SCZ (n = 601), the agreement between patients and their informants on CAI ratings, to explore patients' insight in their cognitive deficits and its relationships with clinical and functional indices. Agreement between patient- and informant-based ratings was assessed by the Gwet's agreement coefficient. Predictors of insight in cognitive deficits were explored by stepwise multiple regression analyses. Patients reported lower severity of cognitive impairment vs. informants. A substantial to almost perfect agreement was observed between patients' and informants' ratings. Lower insight in cognitive deficits was associated to greater severity of neurocognitive impairment and positive symptoms, lower severity of depressive symptoms, and older age. Worse real-life functioning was associated to lower insight in cognitive deficit, worse neurocognitive performance, and worse functional capacity. Our findings indicate that the CAI is a valid co-primary measure with the interview to patients providing a reliable assessment of their cognitive deficits. In the absence of informants with good knowledge of the subject, the interview to the patient may represent a valid alternative
Il paesaggio sonoro in relazione. Suono, movimento e immagini per stimolare complessitĂ percettiva
This article wants to explore the topic of the soundscape in the context of dance and video, especially in the site-specific creation process of dance live performances and video dance, with a brief mention to a particular type of audiovisual installations. The exploration develops starting from the soundscape that two dancing bodies produce merely moving in a dance rehearsal room, it continues with the description of a soundscape composed with sounds detected by a specific environment, and it ends with the analysis of the dance movie Car Men, by Paval Conen. The final reflections start from an example of dramaturgical use of sound in the context of film production and arrive at the description of laser drawing performance as a final example of perceptive complexity
Non-destructive techniques to assess mechanical and physical properties of soft calcarenitic stones
One of the major goals in the field of rehabilitation and renovation of existing structures is to determine mechanical properties of materials as well as their level of damage, namely the presence of defects, cracks, weathering effects, etc., by means of non-destructive (NDT) techniques. NDT tests, in fact, are easier and more economics than destructive ones because they do not necessitate sample extraction and preparation; furthermore they are often the unique way to assess the material properties in case of historic and architectural buildings, where the possibility of extracting core samples is limited or not possible. The ultrasonic pulse velocity testing has been proved to be a useful and reliable non-destructive test for assessing the compressive strength and the elastic modulus of concrete in existing structures. Furthermore, the use of both ultrasonic tests and Schmidt hammer tests allow to have a good estimation of concrete compressive strength (SONREB method) by reducing the influence of the variables affecting the two technique when used alone. Both the technics have also been suggested to investigate mechanical and physical properties of rocks, but further experimental data are needed to confirm the reliability of the method. The present work is a part of a wider research aimed at set up non-invasive diagnostic procedures for the mechanical analysis and qualification of the ancient masonries; it is specifically devoted to verify the effectiveness and/or to point out critical aspects and limits of the above mentioned non-destructive tests - already applied in the field of concrete and compact stones -with reference to the characterization of soft stones
Ultrasonic pulse velocity test for non-destructive investigations of historical masonries: an experimental study of the effect of frequency and applied load on the response of a limestone
The ultrasonic pulse velocity (UPV)
method can be conveniently used for non-destructive testing of physical–mechanical properties of the stones within historical masonry, as well as to check the state of damage and microcracking. Before to proceed with in situ measurements, it is important to assess the contribution that both intrinsic characteristics of the stones and external factors may give to the ultrasonic response. In this work the effect of different wave frequencies, sample geometry and application of a compression load on the response of a natural stone to UPV test has been investigated. An extensive experimental campaign in laboratory conditions was carried out on a soft limestone, used in the historical building heritage of the Southern Italy. A negligible UPV dispersion was found at the used frequencies of 1 MHz, 120 and 55 kHz when a compression load was not applied; the measured velocities were found to be influenced by the stone inhomogeneity rather than by the sample size. They showed a slight decrease and still negligible dispersion under load up to the visible damage. Dispersion increased with the cracking progression. This indicates that enhanced capability of UPV, in checking material quality and damage conditions, can be obtained by combining the use of different wave frequencies
Research of correlations between NDT and DT to assess mechanical properties of a soft stone in ancient masonry
A deep knowledge of the physical and mechanical properties of the constituent materials of ancient masonries is of crucial importance in the choice of the proper intervention technique. In case of historical buildings sustainable diagnostic procedures responding to the conservation constraints, should have the lowest degree of intrusion and the fullest respect for their physical integrity. The sample’s extraction from existing structures for laboratory tests is one of the major problems in the field of diagnosis of ancient buildings and this has moved the scientific community to propose alternative non-destructive techniques to evaluate the mechanical and physical properties of the building stones.
In the present work non-destructive and destructive tests have been investigated as tools for assessing the compressive strength of “Lecce stone”, a soft calcarenitic stone used as traditional building materials in the Southern Italy. Ultrasonic pulse velocity (UPV), Schmidt hammer test and compressive tests on microcores have been compared with mechanical destructive tests on cubes in order to found correlations between the results. The final aim is to assess the reliability of the non-destructive investigated methods in describing the mechanical performance of the stone, reducing the use of destructive analyses on masonries
Assessing the reliability of non-destructive and moderately invasive techniques for the evaluation of uniaxial compressive strength of stone masonry units
In this work Ultrasonic Pulse Velocity (UPV), Schmidt Hammer Rebound (SHR) test and strength
assessment on microcores (UCSm) and standard cubic samples (UCSc) were used to detect the uniaxial
compressive strength of stone masonry units. The analysis of the variability of the measurements allowed
to investigate the significance of each test to differentiate the masonry blocks. The latter was evaluated
by a Variability Index (VI), as the ratio between the variances at block scale and among the blocks. VI was
found higher for UCSc and UPV than for UCSm and SHR measurements. A regression analysis aimed to the
correlation of uniaxial compressive strengths evaluated by conventional destructive test on stone cubes
with the other test results. The findings showed a good linear correlation among UCSc and UPV values
(R2 = 0.83), thus supporting the reliability of UPV to screen the masonry units and to estimate their
uniaxial compressive strength. The correlation of UCSc with UCSm was reasonable (R2 = 0.76), while it
was low with SHR results; some limits related to the use of SHR and UCSm tests are also discussed
Ultrasonic pulse velocity for the evaluation of physical and mechanical properties of a highly porous building limestone
UPV as non-destructive technique can effectively contribute to the low invasive in situ analysis and diagnosis of masonry elements related to the conservation, rehabilitation and strengthening of the built heritage. The use of non-destructive and non-invasive techniques brings all the times many advantages in diagnostic activities on pre-existing buildings in terms of sustainability; moreover, it is a strong necessity with respect to the conservation constraints when dealing with the historical-architectural heritage. In this work laboratory experiments were carried out to investigate the effectiveness of ultrasonic pulse velocity (UPV) in evaluating physical and mechanical properties of Lecce stone, a soft and porous building limestone. UPV and selected physical-mechanical parameters such as density and uniaxial compressive strength (UCS) were determined. Factors such as anisotropy and water presence that induce variations on the ultrasonic velocity were also assessed. Correlations between the analysed parameters are presented and discussed. The presence of water greatly affected the values of the analysed parameters, leading to a decrease of UPV and to a strong reduction of the compressive strength. A discussion of the role of the water on these results is provided. Regression analysis showed a reliable linear correlation between UPV and compressive strength, which allows a reasonable estimation of the strength of Lecce stone by means of non-destructive testing methods such as the ultrasonic wave velocity. Low correlation between UPV and density was found, suggesting that other factors than density, related to the fabric and composition, also influence the response of the selected stone to the UPV. They have no influence on the UCS, that instead showed to be highly correlated with the packing density