856 research outputs found

    Transmission fiber chromatic dispersion dependence on temperature: implications on 40 Gb/s performance

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    In this letter we will evaluate the performance degradation of a 40 km high-speed (40 Gb/s) optical System, induced by optical fiber variations of the chromatic dispersion induced by temperature changes. The chromatic dispersion temperature sensitivity will be estimated based on the signal quality parameters

    Behavioural networks: a new methodology to study birds’ habits

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    We introduce here a new methodology, named Behavioural Networks (BeNe), to thoroughly analyze birds’ habits in space and time. Behavioural Networks are based on GIS technologies, association rules and network capabilities, all applied to GPS data. They return an information-rich and easily-interpretable synthesis of the activities taken by birds during a user-defined time interval. As a case study, we applied BeNe to the Lesser Kestrel Falco naumanni of the Santeramo in Colle colony (Apulia, Italy). Our methodology has been able to extract the main rules of the bird’s behaviour during the most critical part of the chick-rearing period. BeNe can be applied to any bird species, to any time interval and to both local and migratory GPS data

    Nocturnal flights lead to collision risk with power lines and wind farms in Lesser Kestrels: a preliminary assessment through GPS tracking

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    We present here the first report about Lesser Kestrels' flight height behaviour and potential collision risk with wind farms and power lines in two colonies (Gravina in Puglia and Altamura; Apulia, Italy) that present the highest density of Lesser Kestrels worldwide in urban areas. Using accurate GPS data-loggers on nine Lesser Kestrels, we collected data on flight activities during the nestling period. The tracked Lesser Kestrels spent 50% of the monitoring time at heights above ground level (AGL) lower than 41 m, and 75% of time below 98 m AGL. Flight heights resulted not significantly different between the two colonies. Instead, at night Lesser Kestrels resulted to fly at significantly lower altitudes than in the daytime. Our findings, although preliminary, underline the potential collision risk with power lines and wind farms at night in the Lesser Kestrels' colony of Gravina in Puglia. Instead, collision risk resulted negligible during the daytime for both colonies. We conclude that the disappearing of pseudo-steppes in the study area is forcing Lesser Kestrels to flight also at night for foraging purposes during the breading season, which in turn leads to an increased risk of collision with power lines and wind farms
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