Generalized Kerr spacetime with an arbitrary mass quadrupole moment: geometric properties vs particle motion

An exact solution of Einstein's field equations in empty space first found in 1985 by Quevedo and Mashhoon is analyzed in detail. This solution generalizes Kerr spacetime to include the case of matter with arbitrary mass quadrupole moment and is specified by three parameters, the mass $M$, the angular momentum per unit mass $a$ and the quadrupole parameter $q$. It reduces to the Kerr spacetime in the limiting case $q=0$ and to the Erez-Rosen spacetime when the specific angular momentum $a$ vanishes. The geometrical properties of such a solution are investigated. Causality violations, directional singularities and repulsive effects occur in the region close to the source. Geodesic motion and accelerated motion are studied on the equatorial plane which, due to the reflection symmetry property of the solution, turns out to be also a geodesic plane.Comment: 24 pages, IOP macros used, eps figures n. 28; to appear on Classical and Quantum Gravity, 200

Full-scale monitoring of the wind-induced response of vertical slender structures, with fixed and rotating masses

Nowadays, structural monitoring is gaining more and more attention in the field of wind engineering. On the wake of these developments, the thesis develops and applies a comprehensive structural monitoring procedure tailored for the validation and investigation in full-scale of the wind-induced response of vertical slender structures, with fixed and rotating masses. All the main aspects of the monitoring practice are discussed, regarding the number, location and type of the sensors, the acquisition and the transmission of the full-scale data, as well as the management of the experimental database by following an encoded scheme. In addition, the thesis highlights a number of issues typical of the monitoring activity that are not addressed in literature, providing inspiration to solve them. The defined procedure finds application in two monitoring campaigns launched by the Wind Engineering group at the University of Genoa: one slender structure with fixed masses (a light tower) and one slender structure with rotating masses (a small vertical axis wind turbine). As regards the light tower, a reference calculation model of the wind-induced response of poles and towers is selected from literature and is validated in full-scale. The input parameters needed for the application of the model are identified from experimental surveys, intersecting wind tunnel tests and dynamic identification techniques. The results highlight the goodness of the selected model and the large uncertainties associated to the input parameters. As regards the wind turbine, the full-scale data are used to investigate the contribution of the rotating parts to the dynamic behavior. In addition, the fatigue damage of the supporting tower is calculated under stationary and non-stationary excitation due to wind, turbine rotation, emergency stop and start. The results highlight the importance of the detail modeling, the fundamental role played by the non-stationary conditions and the errors committed when using conventional models of the load

Un giornalino scolastico realizzato da ragazzi Down: dalle parole ai fatti

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Preventive strategies in oral health for special needs patients

As regards to the most common oral disease in pediatric patients, intellectual disability is not a risk factor for caries disease itself, but it rather reduces the individual capability to self-care and therefore to his own oral care. Children suffering of systemic pathologies and/or with different stages of disability are to be considered at high risk for dental caries development. According to recent guidelines for oral health prevention in childhood, individual additional strategies for a preventive care should be applied for these patients. All the health providers, family and caregivers should be involved with the aim of being aware, motivated and informed on oral health issues, and a better access system to the dental care structure, both logistic, professional and economical should be assured

THE ROLE OF URBAN TOPOGRAPHY IN THE ORIENTATION OF GREEK TEMPLES: THE CASES OF AKRAGAS AND SELINUNTE

It is well known that the vast majority of the Greek temples of Sicily are oriented to the rising sun. However the factors which influenced the specific orientation of each temple or of each group of temples can be of various nature and no general key is actually applicable. In particular, we show here the role of local topography in orientation, trough two relevant case-studies: the temples of the urban sector of the Valley of the Temples, Akragas, and the temples of Selinunte

Agaricales del Chaco Oriental 1. Primer registro de Tetrapyrgos nigripes (Marasmiaceae) y Xeromphalina tenuipes (Mycenaceae) para la region

Se describen e ilustran a Tetrapyrgos nigripes y Xeromphalina tenuipes, registros nuevos para la región del Chaco Oriental, de estas dos especies pantropicales. Tetrapyrgos nigripes se caracteriza por su píleo centralmente estipitado con esporas tetraédricas y pileipellis con estructuras rameales, mientras que X. tenuipes presenta el píleo amarillento a ocráceo anaranjado, laminillas amarillas más claras y estípite marrón rojizo cubierto por abundantes pelos que le dan un aspecto aterciopelado.Fil: Ramirez, Natalia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); ArgentinaFil: Niveiro, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); ArgentinaFil: Popoff, Orlando Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); Argentin

MODELLING PLASTIC DEFORMATION OF STAINLESS STEEL PIPES

Plastic deformation is the most common technique adopted to manufacture complex shape pieces in the most efficient way. Even higher requirements need to be faced in the different applications. In order to target such requirement quality and compliance tests are carried out aimed to guarantee that these standards are faced; this often means a waste of material and economic resources. A far as concerns welded stainless steel pipes many criticises affecting the general trend of subsequent machining need to be considered. In this paper the effects of different process parameters and geometrical constrains on austenitic stainless steel pipe forming are studied by Finite Elements Method (FEM) simulations. The model sensitivity to input parameters is reported. The feasibility of the simulated process is evaluated through the use of Forming Limit Diagrams (FLD). </p

Wind and structural response monitoring of a lighting pole for the study of downburst effects on structures

Wind excited response of structures due to downbursts has been studied using wind tunnel simulations, computational fluid dynamics applications, and analytical procedures in the previous two decades. However, the studies have not been validated with full-scale wind and structural response measurements. To fill this research gap, continuous wind-and-structural response monitoring of three slender structures was implemented through the European research council-funded project, THUNDERR. This paper focuses on one of the monitored structures, describing the monitoring system, the dynamic and aerodynamic properties, and the registered data during two downburst events. The wind-excited response of the monitored structure during two case studies of downbursts is analyzed. The correlation between the wind speed and structural displacement parameters was also studied and the square of mean wind speed was found to be highly correlated with the mean displacement and the standard deviation of the fluctuating displacement. The fluctuating components of wind speed and top displacement were found to be partially correlated. The simplicity of the selected structure, and the possibility of obtaining both the quasi-steady and resonant components of the structural response from strain registrations, will make this study a benchmark for the validation of methods and simulations of down burst wind load