Neural Nets and Star/Galaxy Separation in Wide Field Astronomical Images

One of the most relevant problems in the extraction of scientifically useful information from wide field astronomical images (both photographic plates and CCD frames) is the recognition of the objects against a noisy background and their classification in unresolved (star-like) and resolved (galaxies) sources. In this paper we present a neural network based method capable to perform both tasks and discuss in detail the performance of object detection in a representative celestial field. The performance of our method is compared to that of other methodologies often used within the astronomical community.Comment: 6 pages, to appear in the proceedings of IJCNN 99, IEEE Press, 199

Electronic transport within a quasi two-dimensional model for rubrene single-crystal field effect transistors

Spectral and transport properties of the quasi two-dimensional adiabatic Su-Schrieffer-Heeger model are studied adjusting the parameters in order to model rubrene single-crystal field effect transistors with small but finite density of injected charge carriers. We show that, with increasing temperature $T$, the chemical potential moves into the tail of the density of states corresponding to localized states, but this is not enough to drive the system into an insulating state. The mobility along different crystallographic directions is calculated including vertex corrections which give rise to a transport lifetime one order of magnitude smaller than spectral lifetime of the states involved in the transport mechanism. With increasing temperature, the transport properties reach the Ioffe-Regel limit which is ascribed to less and less appreciable contribution of itinerant states to the conduction process. The model provides features of the mobility in close agreement with experiments: right order of magnitude, scaling as a power law $T^{-\gamma}$, with $\gamma$ close or larger than two, and correct anisotropy ratio between different in-plane directions. Due to a realistic high dimensional model, the results are not biased by uncontrolled approximations.Comment: 10 pages, 9 figures, Submitte

Chronicle of a death foretold. It is time for echocardiographic screening in young athletes

Background: The novel "Chronicle of a death foretold" by Gabriel Garcia Marquez is a story of a sudden death which could have been prevented. In 1976, within the University of Maryland basketball program and only 8 weeks apart, two athletes died suddenly during physical exertion. They were affected by hypertrophic cardiomyopathy and Marfan syndrome and in both cases an echocardiogram would have prevented the tragic epilogue. This coincidence drew everyone's attention and experts' interest on sudden death in sports.Methods and results: Even in recent Italian history, unexpected deaths continue to affect athletes but surprisingly any real knowledge regarding the numbers and the impact of those tragedies must take medical literature and non-medical press into consideration. Herein we report the clinical case of a 13-year-old patient with a bicuspid aortic valve, whose mother was alarmed by the news of a young boy who died because of an anomalous origin of coronary artery (AOCA) which had not been diagnosed at transthoracic echocardiography (TTE). Her obstinacy induced the physicians to repeat TTE and led to the same diagnosis in her son: actually, his right coronary artery originated from the opposite sinus of Valsalva. The suspicion was confirmed by coronary CT scan and, thanks to appropriate therapy, the boy now fares well.Conclusions: AOCA is the second most common cause of sudden death in young athletes. Although AOCA is often undetectable at ECG, TTE increases sensitivity of preparticipation screening. It could therefore allow us to avoid such coincidences and prevent sudden juvenile death

Double modelling of the dynamic of activities in rural municipalities.

Land use choices and activity prevalence in a selected territory are determined by individual preferences constrained by the characteristic of the analysed zone: population density, soil properties, urbanization level and other similar factors can drive individuals to make different kind of decisions about their occupations. Different approaches can be used to describe land use change, occupation prevalence and their reciprocal inter-relation. In this paper we describe two different kinds of approaches: an agent based model, centred on individual choices and an aggregated model describing the evolution of activity prevalence in terms of coupled differential equation. We use and we compare the two models to analyse the effect of territorial constraints, like the lack of employment in determined sectors, on the possible activity prevalence scenarios.SBIAgro 2009

Characterization of Building Thermal Energy Consumption at the Urban Scale

The ongoing urban transition toward decarbonized energy systems has raised the attention on local energy planning practices. Besides the multiple actors involved in the planning process, the complexity of the urban energy systems requires the elaboration of heterogeneous data. In such contest, the paper introduces and compares two GIS-based ethodologies for supporting the spatial characterization of the local residential built environment in terms of building distribution and space heating energy consumption. Starting from the assessment of residential consumption, a third method for the characterization of non-residential building thermal energy consumption is proposed. From a bottom-up perspective, in both residential models all the buildings are geo-referenced and clustered according to their thermo-physical characteristics. From a top-down perspective, energy balance data are used to calibrate the bottom-up results and to match the total building loads. The procedure, tested on the city of Turin as case study, allows assessing the energy use of buildings and to create urban energy maps. The energy spatial characterization of a territory is the basis for performing short and long-term scenarios analysis. Results of this method can be useful to: i. decision maker to understand the current state of the territorial energy consumption to identify critical energy intense areas; ii. citizens for visualising their energy consumption and iii. researchers for setting up the basis of further urban analysis

Kinetic Monte Carlo simulation of molecular processes on supported metal particles

A general model is proposed to describe the kinetics of molecular reactions taking place on supported metal particles, which are deformed by the effect of temperature, through kinetic Monte Carlo simulations. The model is applied to the study of the CO oxidation reaction. The effects of adsorbate-adsorbate and adsorbate-metal interactions and of CO and metal atoms diffusion on the reaction window and the overall reaction rate are determined.Fil: Sales, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Gargiulo Almeida, María Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Zgrablich, G.. Universidad Nacional de San Luis; Argentin