Embracing transience and subjectivity in the conservation of complex contemporary artworks: contributions from ethnographic and psychological paradigms

Dissertação para obtenção do Grau de Mestre em Conservação e Restauro, Perfil Ciências da Conservação Especialização em Arte Contemporânea

Structure-properties relationships in thermoplastic polyurethane elastomer nanocomposites: Interactions between polymer phases and nanofillers

Polyurethane thermoplastic elastomer (TPU) nanocomposites were prepared by the incorporation of 1 wt% of high-structured carbon black (HSCB), carbon nanofibers (CNF), nanosilica (NS) and nanoclays (NC), following a proper high-shear blending procedure. The TPU nanofilled mechanical properties and morphology was assessed. The nanofillers interact mainly with the TPU hard segments (HS) domains, determining their glass transition temperature, and increasing their melting temperature and enthalpy. A significant improvement upon the modulus, sustained stress levels and deformation capabilities is evidenced. The relationships between the morphology and the nanofilled TPU properties are established, evidencing the role of HS domains on the mechanical response, regardless the nanofiller type.

Mechanical vs. electrical hysteresis of carbon nanotube/styrene-butadiene-styrene composites and their influence in the electromechanical response

The interesting properties of thermoplastics elastomers can be combined with carbon nanotubes (CNT) for the development of large strain piezoresistive composites for sensor applications. Piezoresistive properties of the composites depend on CNT content, with the gauge factor increasing for concentrations around the percolation threshold, mechanical and electrical hysteresis. The SBS copolymer composition (butadiene/styrene ratio) influences the mechanical and electrical hysteresis of composites and, therefore, the piezoresistive response. This work reports on the electrical and mechanical response of CNT/SBS composites with 4%wt nanofiller content, due to the larger electromechanical response. C401 and C540 SBS copolymers with 80% and 60% butadiene content, respectively have been selected. The copolymer with larger amount of soft phase (C401) shows a rubber-like mechanical behavior, with mechanical hysteresis increasing linearly with strain until 100% strain. The copolymer with the larger amount of hard phase (C540) just shows rubber-like behavior for low strains. The piezoresistive sensibility is similar for both composites for low strains, with a GF≈ 5 for 5% strain. The electrical hysteresis shows opposite behavior than the mechanical hysteresis, increasing with strain for both composites, but with higher increase for softer copolymer, C401. The GF increases with increasing strain, but this increase is larger for composites with lower amounts of soft phase due to the distinct initial modulus and deformation of the soft and hard phases of the copolymer. The soft phase shows larger strain under a given stress than the harder phase and the conductive pathway rearrangements in the composites are different for both phases, the harder copolymer (C540) showing higher piezoresistive sensibility, GF≈ 18, for 20% strain.

Insights into bacterial colony morphology evolution and diversification during infection development in cystic fibrosis

Tese de Doutoramento em Engenharia Biomédica.

Predicting trabecular bone microdamage initiation and accumulation using a non-linear perfect damage model

Studies evaluating the mechanical behavior of the trabecular microstructure play an important role in our understanding of pathologies such as osteoporosis, and in increasing our understanding of bone fracture and bone adaptation. Understanding of such behavior in bone is important for predicting and providing early treatment of fractures. The objective of this study is to present a numerical model for studying the initiation and accumulation of trabecular bone microdamage in both the pre- and post-yield regions. A sub-region of human vertebral trabecular bone was analyzed using a uniformly loaded anatomically accurate microstructural three-dimensional finite element model. The evolution of trabecular bone microdamage was governed using a non-linear, modulus reduction, perfect damage approach derived from a generalized plasticity stress-strain law. The model introduced in this paper establishes a history of microdamage evolution in both the pre- and post-yield regions

Device-specific weighted T-score for two quantitative ultrasounds: operational propositions for the management of osteoporosis for 65 years and older women in Switzerland.

The World Health Organization (WHO) criteria for the diagnosis of osteoporosis are mainly applicable for dual X-ray absorptiometry (DXA) measurements at the spine and hip levels. There is a growing demand for cheaper devices, free of ionizing radiation such as promising quantitative ultrasound (QUS). In common with many other countries, QUS measurements are increasingly used in Switzerland without adequate clinical guidelines. The T-score approach developed for DXA cannot be applied to QUS, although well-conducted prospective studies have shown that ultrasound could be a valuable predictor of fracture risk. As a consequence, an expert committee named the Swiss Quality Assurance Project (SQAP, for which the main mission is the establishment of quality assurance procedures for DXA and QUS in Switzerland) was mandated by the Swiss Association Against Osteoporosis (ASCO) in 2000 to propose operational clinical recommendations for the use of QUS in the management of osteoporosis for two QUS devices sold in Switzerland. Device-specific weighted "T-score" based on the risk of osteoporotic hip fractures as well as on the prediction of DXA osteoporosis at the hip, according to the WHO definition of osteoporosis, were calculated for the Achilles (Lunar, General Electric, Madison, Wis.) and Sahara (Hologic, Waltham, Mass.) ultrasound devices. Several studies (totaling a few thousand subjects) were used to calculate age-adjusted odd ratios (OR) and area under the receiver operating curve (AUC) for the prediction of osteoporotic fracture (taking into account a weighting score depending on the design of the study involved in the calculation). The ORs were 2.4 (1.9-3.2) and AUC 0.72 (0.66-0.77), respectively, for the Achilles, and 2.3 (1.7-3.1) and 0.75 (0.68-0.82), respectively, for the Sahara device. To translate risk estimates into thresholds for clinical application, 90% sensitivity was used to define low fracture and low osteoporosis risk, and a specificity of 80% was used to define subjects as being at high risk of fracture or having osteoporosis at the hip. From the combination of the fracture model with the hip DXA osteoporotic model, we found a T-score threshold of -1.2 and -2.5 for the stiffness (Achilles) determining, respectively, the low- and high-risk subjects. Similarly, we found a T-score at -1.0 and -2.2 for the QUI index (Sahara). Then a screening strategy combining QUS, DXA, and clinical factors for the identification of women needing treatment was proposed. The application of this approach will help to minimize the inappropriate use of QUS from which the whole field currently suffers.

EFNS guidelines on diagnosis and management of neuromyelitis optica.

BACKGROUND AND PURPOSE: Neuromyelitis optica (NMO) or Devic's disease is a rare inflammatory and demyelinating autoimmune disorder of the central nervous system (CNS) characterized by recurrent attacks of optic neuritis (ON) and longitudinally extensive transverse myelitis (LETM), which is distinct from multiple sclerosis (MS). The guidelines are designed to provide guidance for best clinical practice based on the current state of clinical and scientific knowledge. SEARCH STRATEGY: Evidence for this guideline was collected by searches for original articles, case reports and meta-analyses in the MEDLINE and Cochrane databases. In addition, clinical practice guidelines of professional neurological and rheumatological organizations were studied. RESULTS: Different diagnostic criteria for NMO diagnosis [Wingerchuk et al. Revised NMO criteria, 2006 and Miller et al. National Multiple Sclerosis Society (NMSS) task force criteria, 2008] and features potentially indicative of NMO facilitate the diagnosis. In addition, guidance for the work-up and diagnosis of spatially limited NMO spectrum disorders is provided by the task force. Due to lack of studies fulfilling requirement for the highest levels of evidence, the task force suggests concepts for treatment of acute exacerbations and attack prevention based on expert opinion. CONCLUSIONS: Studies on diagnosis and management of NMO fulfilling requirements for the highest levels of evidence (class I-III rating) are limited, and diagnostic and therapeutic concepts based on expert opinion and consensus of the task force members were assembled for this guideline.

Complex landslide behaviour and structural controlled by the structures: A 3D conceptual model example of Åknes rockslide, Norway

Åknes is an active complex large rockslide of approximately 30?40 Mm3 located within the Proterozoic gneisses of western Norway. The observed surface displacements indicate that this rockslide is divided into several blocks moving in different directions at velocities of between 3 and 10 cm year?1. Because of regional safety issues and economic interests this rockslide has been extensively monitored since 2004. The understanding of the deformation mechanism is crucial for the implementation of a viable monitoring system. Detailed field investigations and the analysis of a digital elevation model (DEM) indicate that the movements and the block geometry are controlled by the main schistosity (S1) in gneisses, folds, joints and regional faults. Such complex slope deformations use pre-existing structures, but also result in new failure surfaces and deformation zones, like preferential rupture in fold-hinge zones. Our interpretation provides a consistent conceptual three-dimensional (3D) model for the movements measured by various methods that is crucial for numerical stability modelling. In addition, this reinterpretation of the morphology confirms that in the past several rockslides occurred from the Åknes slope. They may be related to scars propagating along the vertical foliation in folds hinges. Finally, a model of the evolution of the Åknes slope is presented.

Comment on "Streaming potential dependence on water-content in Fontainebleau sand" by V. Allegre, L. Jouniaux, F. Lehmann and P. Sailhac

Allegre et al. recently presented new experimental data regarding the dependence of the streaming potential coupling coefficient with the saturation of the water phase. Such experiments are important to model the self-potential response associated with the flow of water in the vadose zone and the electroseismic/seismoelectric conversions in unsaturated porous media. However, the approach used to interpret the data is questionable and the conclusions reached by Allegre et al. likely incorrect

Trabecular Bone Score Helps Classifying Women At Riskof Fracture Prospectively In The Ofely Study

Objectives: Trabecular Bone Score (TBS, Med-Imaps, France) is an index of bone microarchitecture calculated from antero-posterior spine DXA scan and reported to be associated with fracture in prior case-control studies and in a large prospective study with the Prodigy DXA device. Our aim was to assess the ability of TBS to predict incident fracture and improve the classification of fracture prospectively in the OFELY study.Materials/Methods: TBS was assessed in 564 postmenopausal women (66±8 years old) from the OFELY cohort, who had a spine DXA scan (QDR 4500A, Hologic, USA) between year 2000 and 2001. During a mean follow up of 7.8±1.3 years, 94 women sustained a fragility fracture.Results: At the time of baseline DXA scan, women with incident fracture were significantly older (70±9 vs. 65± 8 years), had a lower spine BMD (T-score: −1.9±1.2 vs. −1.3±1.3, p<0.001) and spine TBS (−3.1%, p<0.001) than women without incident fracture. After adjustment for age, BMI and the presence of prevalent fracture, the magnitude of fracture prediction was similar for spine BMD (OR=1.42 [1.11;1.82] per SD decrease [95% CI]) and TBS (OR=1.34 [1.04;1.74]) but the combination of TBS and spine BMD did not improve fracture prediction. Spine BMD and TBS were both correlated with age (respectively r=−0.17 and −0.49, p<0.001) and correlated together with 39% of TBS explained by spine BMD (r=0.63, p<0.001). When using the WHO classification, 38% of the fractures occurred in osteoporotic (fracture rate=29%), 47% in osteopenic (fracture rate=16%) and 15% in women with T-score >−1 (fracture rate=9%). By classifying our population in tertiles of TBS, we found that 47% of the fractures occurred in the lowest tertile of TBS (fracture rate=23%) and 39% of the fracture that occurred in osteopenic women were in the lowest tertile of TBS.Conclusions: Spine BMD and TBS predicted fractures equally well. The addition of TBS to spine BMD added only limited information on fracture risk prediction in our cohort when considering the all range of BMD. Nevertheless combining the osteopenic T-score and the lowest TBS helped defining a subset of osteopenic women at higher risk of fracture.Disclosure of Interest: None declared.

Qualité des données fournies par la statistique médicale VESKA: le cas de la fracture du fémur proximal. [Quality of data provided by VESKA medical statistics: the case of the fractured proximal femur].

Within the framework of a retrospective study of the incidence of hip fractures in the canton of Vaud (Switzerland), all cases of hip fracture occurring among the resident population in 1986 and treated in the hospitals of the canton were identified from among five different information sources. Relevant data were then extracted from the medical records. At least two sources of information were used to identify cases in each hospital, among them the statistics of the Swiss Hospital Association (VESKA). These statistics were available for 9 of the 18 hospitals in the canton that participated in the study. The number of cases identified from the VESKA statistics was compared to the total number of cases for each hospital. For the 9 hospitals the number of cases in the VESKA statistics was 407, whereas, after having excluded diagnoses that were actually "status after fracture" and double entries, the total for these hospitals was 392, that is 4% less than the VESKA statistics indicate. It is concluded that the VESKA statistics provide a good approximation of the actual number of cases treated in these hospitals, with a tendency to overestimate this number. In order to use these statistics for calculating incidence figures, however, it is imperative that a greater proportion of all hospitals (50% presently in the canton, 35% nationwide) participate in these statistics.

Trabecular bone score improves fracture risk prediction in non-osteoporotic women: the OFELY study.

The use of areal bone mineral density (aBMD) for fracture prediction may be enhanced by considering bone microarchitectural deterioration. Trabecular bone score (TBS) helped in redefining a significant subset of non-osteoporotic women as a higher risk group. INTRODUCTION: TBS is an index of bone microarchitecture. Our goal was to assess the ability of TBS to predict incident fracture. METHODS: TBS was assessed in 560 postmenopausal women from the Os des Femmes de Lyon cohort, who had a lumbar spine (LS) DXA scan (QDR 4500A, Hologic) between years 2000 and 2001. During a mean follow-up of 7.8 ± 1.3 years, 94 women sustained 112 fragility fractures. RESULTS: At the time of baseline DXA scan, women with incident fracture were significantly older (70 ± 9 vs. 65 ± 8 years) and had a lower LS_aBMD and LS_TBS (both -0.4SD, p < 0.001) than women without fracture. The magnitude of fracture prediction was similar for LS_aBMD and LS_TBS (odds ratio [95 % confidence interval] = 1.4 [1.2;1.7] and 1.6 [1.2;2.0]). After adjustment for age and prevalent fracture, LS_TBS remained predictive of an increased risk of fracture. Yet, its addition to age, prevalent fracture, and LS_aBMD did not reach the level of significance to improve the fracture prediction. When using the WHO classification, 39 % of fractures occurred in osteoporotic women, 46 % in osteopenic women, and 15 % in women with T-score > -1. Thirty-seven percent of fractures occurred in the lowest quartile of LS_TBS, regardless of BMD. Moreover, 35 % of fractures that occurred in osteopenic women were classified below this LS_TBS threshold. CONCLUSION: In conclusion, LS_aBMD and LS_TBS predicted fractures equally well. In our cohort, the addition of LS_TBS to age and LS_aBMD added only limited information on fracture risk prediction. However, using the lowest quartile of LS_TBS helped in redefining a significant subset of non-osteoporotic women as a higher risk group which is important for patient management.

Comparison of 2 frailty indexes for prediction of falls, disability, fractures, and death in older women.

BACKGROUND: Frailty, as defined by the index derived from the Cardiovascular Health Study (CHS index), predicts risk of adverse outcomes in older adults. Use of this index, however, is impractical in clinical practice. METHODS: We conducted a prospective cohort study in 6701 women 69 years or older to compare the predictive validity of a simple frailty index with the components of weight loss, inability to rise from a chair 5 times without using arms, and reduced energy level (Study of Osteoporotic Fractures [SOF index]) with that of the CHS index with the components of unintentional weight loss, poor grip strength, reduced energy level, slow walking speed, and low level of physical activity. Women were classified as robust, of intermediate status, or frail using each index. Falls were reported every 4 months for 1 year. Disability (> or =1 new impairment in performing instrumental activities of daily living) was ascertained at 4(1/2) years, and fractures and deaths were ascertained during 9 years of follow-up. Area under the curve (AUC) statistics from receiver operating characteristic curve analysis and -2 log likelihood statistics were compared for models containing the CHS index vs the SOF index. RESULTS: Increasing evidence of frailty as defined by either the CHS index or the SOF index was similarly associated with an increased risk of adverse outcomes. Frail women had a higher age-adjusted risk of recurrent falls (odds ratio, 2.4), disability (odds ratio, 2.2-2.8), nonspine fracture (hazard ratio, 1.4-1.5), hip fracture (hazard ratio, 1.7-1.8), and death (hazard ratio, 2.4-2.7) (P < .001 for all models). The AUC comparisons revealed no differences between models with the CHS index vs the SOF index in discriminating falls (AUC = 0.61 for both models; P = .66), disability (AUC = 0.64; P = .23), nonspine fracture (AUC = 0.55; P = .80), hip fracture (AUC = 0.63; P = .64), or death (AUC = 0.72; P = .10). Results were similar when -2 log likelihood statistics were compared. CONCLUSION: The simple SOF index predicts risk of falls, disability, fracture, and death as well as the more complex CHS index and may provide a useful definition of frailty to identify older women at risk of adverse health outcomes in clinical practice.

Efecto de la microestructura en el comportamiento mecánico de aceros de herramienta para trabajo en frío

El estudio desarrollado en la tesis doctoral profundiza en las relaciones existentes entre la microestructura y el comportamiento a rotura y fatiga de tres tipos de Aceros de Herramienta para trabajo en Frío, dos obtenidos por colada y un tercero mediante pulvimetalúrgia. En primer lugar se evaluaron los aspectos microestructurales relacionados con las dos vias de procesamiento empleadas, además del efecto del cambio en la composición química. Asimismo se documentó la influencia del trabajado en caliente sobre la isotropía microestructural. Considerando las caracteristicas microestructurales se evaluó el comportamiento a rotura en tres orientaciones referidas al sentido de la deformación en caliente. Para ello , se empleó la Mecánica de la Fractura Elástica Lineal como marco analítico. Los resultados fueron tratados siguiendo la estadística de Weibull. Para el caso de los aceros colados se implementa un analisis de curva-R para explicar el crecimiento subcrítico de grietas observado experimentalmente. El estudio del comportamiento a fatiga incluyó la determinación del limite a fatiga para todas la orientaciones microestructurales escogidas y el estudio de la cinetica de propagación de fisuras físicamente pequeñas para la orientación con mejor respuesta mecánica.

The use of clinical risk factors enhances the performance of BMD in the prediction of hip and osteoporotic fractures in men and women.

SUMMARY: BMD and clinical risk factors predict hip and other osteoporotic fractures. The combination of clinical risk factors and BMD provide higher specificity and sensitivity than either alone. INTRODUCTION AND HYPOTHESES: To develop a risk assessment tool based on clinical risk factors (CRFs) with and without BMD. METHODS: Nine population-based studies were studied in which BMD and CRFs were documented at baseline. Poisson regression models were developed for hip fracture and other osteoporotic fractures, with and without hip BMD. Fracture risk was expressed as gradient of risk (GR, risk ratio/SD change in risk score). RESULTS: CRFs alone predicted hip fracture with a GR of 2.1/SD at the age of 50 years and decreased with age. The use of BMD alone provided a higher GR (3.7/SD), and was improved further with the combined use of CRFs and BMD (4.2/SD). For other osteoporotic fractures, the GRs were lower than for hip fracture. The GR with CRFs alone was 1.4/SD at the age of 50 years, similar to that provided by BMD (GR = 1.4/SD) and was not markedly increased by the combination (GR = 1.4/SD). The performance characteristics of clinical risk factors with and without BMD were validated in eleven independent population-based cohorts. CONCLUSIONS: The models developed provide the basis for the integrated use of validated clinical risk factors in men and women to aid in fracture risk prediction.