Diamagnetic Interactions in Disordered Suspensions of Metastable Superconducting Granules

The simulation of the transition sequence of superheated Type I superconducting granules (SSG) in disordered suspensions when an external magnetic field is slowly increased from zero has been studied. Simulation takes into account diamagnetic interactions and the presence of surface defects. Results have been obtained for the transition sequence and surface fields distribution covering a wide range of densities. These results are compared with previous analytical perturbative theory, which provides qualitative information on transitions and surface magnetic fields during transitions, but with a range of validity apparently limited to extremely dilute samples. Simulations taking into account the complete diamagnetic interactions between spheres appear to be a promising tool in interpreting SSG experiments, in applications such as particle detectors, and in some fundamental calculations of Solid State Physics.Comment: 25 pages, 11 figures, accepted for publication in European Physics Journal

External temperature effects on the hysteresis of NiTi wires in dampers for stay-cables

The use of NiTi wires, one of the Shape Memory Alloy (SMA) materials that permits efficient damping in stayed cables for bridges, requires an appropriate behavior when exposed to the external temperature effects. The Clausius-Clapeyron thermodynamic equation establishes a shift of the hysteretic cycle in the stress-temperature representation of about 6 MPa/K for the used wires of diameter 2.46 mm. Hence, an adequate experimental study is necessary to characterize the temperature effects in working conditions. The conducted analysis is twofold. First, the practical evolution of the hysteresis cycle is investigated. The results suggest that the wire permits a completely satisfactory use for temperatures as low as 253 K (i.e., -20 oC). Second, the focus is placed on the effects of extreme winter actions (i.e., as low as 233 K or -40 oC). A preliminary stress aging process at 373K seems adequate to this requirement. Indeed, after the stress aging, the SMA wire increases their working domain by 300 or 400 MPa and the temperature domain is expanded by 30 – 50 K. Measurements visualizing recoverable dynamical actions in the SMA alloys are also outlined.Peer ReviewedPostprint (published version

Interactions Amongst the Community of Endemic Pathogens of African Cattle: A Longitudinal Study in South East Uganda

The work presented in this thesis is focused upon the community of endemic pathogens of African cattle in Sub-Saharan Africa, which has long constrained livestock production in these areas. The first aim of this work is to investigate whether the pathogen community as a whole shapes the ensuant epidemiology and morbidity which are currently attributed to any of its individual pathogens. The second aim is to determine if a greater understanding of the interactions present amongst genetically distinct parasites of the same species can be used to better explain epidemiological features that are at present poorly understood. Emphasis is placed on examining spatial variation in the epidemiology of Theileria parva, a tick-transmitted protozoan that causes East Coast Fever. To achieve these aims, this work examines field data collected from a large and comprehensive study conducted in south east Uganda. Through application of apposite statistical techniques and mathematical modelling, aspects of the complex relations amongst the pathogen community and their environment are explored. Evidence is presented that demonstrates the paramount role of the pathogen community as a whole in shaping the infection dynamics and pathogenicity of any of its individual components. By focusing on a single member of this pathogen community (Theileria parva), some of the influences of host, vector, geographical location, temporal dynamics and intra-species pathogen interactions are elucidated. Application of a polymorphic molecular marker to Theileria parva infected blood samples and the use of Cox proportional hazard analysis, show variability in the survival of infections in cattle in high and low tick challenge areas. Moreover infection survival, which plays a pivotal role in parasite transmission, is shown to be a function of the interactions established amongst genetically distinct co-infective parasites. In consequence, vector intensity alone is insufficient to develop reliable transmission models which can accurately predict the epidemiology of the parasite inside and outside enzootic belts. Finally, a theoretical model is developed which, based upon the field evidence obtained throughout this work, provides a possible explanation for the mechanics of T. parva survival in cattle. In summary, this thesis makes a case that consideration of both inter- and intra-species pathogen interactions, can greatly augment understanding of the epidemiology of these pathogen communities. An integrated approach to pathogen dynamics can better equip an integrated approach to control of important diseases of African cattle

Fatores de incentivo à servitização através da integração do serviço ao cliente no processo de desenvolvimento de produtos

O Desenvolvimento de Produto (DP) ganhou o posto de processo contínuo dentro das organizações em função do baixo ciclo de vida dos produtos no mercado. Este processo é realizado por times multidisciplinares, mas a área de serviços e pós-venda atua só como executora e não atua nas fases de definição de escopo, mesmo tendo uma visão mais clara sobre a perspectiva do cliente. Neste sentido, o estudo sobre o impacto da integração do Serviço ao Cliente no Processo de Desenvolvimento de Produtos (PDP) se faz necessário. O objetivo deste trabalho é a análise do potencial para servitização existente na intervenção do setor de pós-venda nas diferentes etapas do PDP. O método utilizado para realizar esta análise será a revisão da literatura sobre os fatores de impacto de serviços para o desenvolvimento de Sistemas Produto-Serviço e entrevistas com profissionais de desenvolvimento de produtos e serviços. Como resultado, obtiveram-se um conjunto de proposições que discorrem sobre modelos alternativos para a servitização dentro do PDP.Outgoin

Diamagnetic interactions in superheated-superconducting microgranules under an external magnetic field

L'estudi de les transicions produïdes en conjunts de grànuls superconductors metastables té nterès tant per a la física fonamental com per a aplicacions com ara els detectors de partícules. L'estudi teòric d'aquest problema ha estat obstaculitzat per la dificultat del tractament de les interaccions diamagnètiques entre grànuls. En aquesta revisió descrivim el comportament d'aquests sistemes, desenvolupem el mètode numèric del tractament i presentem uns quants resultats experimentals i numèrics.The study of the phase transitions produced in ensembles of metastable superconducting granules by magnetic field variations is important both for fundamental physics and for applications in particle detectors. Theoretical study of the problem has long been hampered by the difficulty in dealing with the diamagnetic interactions between granules. In this review we describe the behaviour of such systems, develop numerical procedures to deal with them, and present some experimental and numerical results

The SMA: an effective damper in civil engineering that smoothes oscillations

The properties of SMA (Shape Memory Alloys, that are smart materials) are associated to a first order phase transition named martensitic transformation that occurs between metastable phases: austenite and martensite. At upper temperature or at lower stress the austenite is the metastable phase. The martensite appears at lower temperature or higher stresses. The hysteresis of the transformation permits different levels of applications, i.e., in their use as a damper. Two types of applications can be considered in damping of structures in Civil Engineering. The first one is related to diminishing the damage induced by earthquakes. The second one is a reduction of oscillation amplitude associate to an increase of the lifetime for the stayed cables in bridges.Peer Reviewe

Interpreting Encoding and Decoding Models

Encoding and decoding models are widely used in systems, cognitive, and computational neuroscience to make sense of brain-activity data. However, the interpretation of their results requires care. Decoding models can help reveal whether particular information is present in a brain region in a format the decoder can exploit. Encoding models make comprehensive predictions about representational spaces. In the context of sensory systems, encoding models enable us to test and compare brain-computational models, and thus directly constrain computational theory. Encoding and decoding models typically include fitted linear-model components. Sometimes the weights of the fitted linear combinations are interpreted as reflecting, in an encoding model, the contribution of different sensory features to the representation or, in a decoding model, the contribution of different measured brain responses to a decoded feature. Such interpretations can be problematic when the predictor variables or their noise components are correlated and when priors (or penalties) are used to regularize the fit. Encoding and decoding models are evaluated in terms of their generalization performance. The correct interpretation depends on the level of generalization a model achieves (e.g. to new response measurements for the same stimuli, to new stimuli from the same population, or to stimuli from a different population). Significant decoding or encoding performance of a single model (at whatever level of generality) does not provide strong constraints for theory. Many models must be tested and inferentially compared for analyses to drive theoretical progress.Comment: 19 pages, 2 figures, author preprin

Effects of strain aging in NiTi SMA wires for dampers

SMA NiTi wires experience evolution under constrained aging. A strain and temperature aging sequence is designed and experimented, to ascertain the functionality of the dampers exposed to weatheringPostprint (published version

Intestinal Dysbiosis and Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) affects 20–30% of the population, with an increased prevalence in industrialized regions. Some patients with NAFLD develop an inflammatory condition termed non-alcoholic steatohepatitis (NASH) that is characterized by hepatocellular injury, innate immune cell-mediated inflammation, and progressive liver fibrosis. In clinical practice, abdominal imaging, which reveals hepatic steatosis, is sufficient for NAFLD diagnosis if other diseases have been rejected. However, a liver biopsy is needed to differentiate NASH from simple steatosis. Therapeutic strategies used to treat obesity and metabolic syndrome improve NAFLD, but there is no specific treatment effective for NASH. The gut microbiota (GM) is composed of millions of microorganisms. Changes in the GM have a significant impact on host health. Intestinal dysbiosis is an imbalance in the GM that can induce increased permeability of the epithelial barrier, with migration of GM-derived mediators through portal vein to the liver. These mediators, such as lipopolysaccharides, short-chain fatty acids, bile acids (BAs), choline, and endogenous ethanol, seem to be involved in NAFLD pathogenesis. Given this evidence, it would be interesting to consider GM-derived mediator determination through omics techniques as a noninvasive diagnostic tool for NASH and to focus research on microbiota modulation as a possible treatment for NASH