Long-term trends in survival of a declining population: the case of the little owl (Athene noctua) in the Netherlands

The little owl (Athene noctua) has declined significantly in many parts of Europe, including the Netherlands. To understand the demographic mechanisms underlying their decline, we analysed all available Dutch little owl ringing data. The data set spanned 35 years, and included more than 24,000 ringed owls, allowing detailed estimation of survival rates through multi-state capture–recapture modelling taking dispersal into account. We investigated geographical and temporal variation in age-specific survival rates and linked annual survival estimates to population growth rate in corresponding years, as well as to environmental covariates. The best model for estimating survival assumed time effects on both juvenile and adult survival rates, with average annual survival estimated at 0.258 (SE = 0.047) and 0.753 (SE = 0.019), respectively. Juvenile survival rates decreased with time whereas adult survival rates fluctuated regularly among years, low survival occurring about every 4 years. Years when the population declined were associated with low juvenile survival. More than 60% of the variation in juvenile survival was explained by the increase in road traffic intensity or in average temperature in spring, but these correlations rather reflect a gradual decrease in juvenile survival coinciding with long-term global change than direct causal effects. Surprisingly, vole dynamics did not explain the cyclic dynamics of adult survival rate. Instead, dry and cold years led to low adult survival rates. Low juvenile survival rates, that limit recruitment of first-year breeders, and the regular occurrence of years with poor adult survival, were the most important determinants of the population decline of the little owl

Long-term trends in survival of a declining population: the case of the little owl (Athene noctua) in the Netherlands

The little owl (Athene noctua) has declined significantly in many parts of Europe, including the Netherlands. To understand the demographic mechanisms underlying their decline, we analysed all available Dutch little owl ringing data. The data set spanned 35 years, and included more than 24,000 ringed owls, allowing detailed estimation of survival rates through multi-state capture–recapture modelling taking dispersal into account. We investigated geographical and temporal variation in age-specific survival rates and linked annual survival estimates to population growth rate in corresponding years, as well as to environmental covariates. The best model for estimating survival assumed time effects on both juvenile and adult survival rates, with average annual survival estimated at 0.258 (SE = 0.047) and 0.753 (SE = 0.019), respectively. Juvenile survival rates decreased with time whereas adult survival rates fluctuated regularly among years, low survival occurring about every 4 years. Years when the population declined were associated with low juvenile survival. More than 60% of the variation in juvenile survival was explained by the increase in road traffic intensity or in average temperature in spring, but these correlations rather reflect a gradual decrease in juvenile survival coinciding with long-term global change than direct causal effects. Surprisingly, vole dynamics did not explain the cyclic dynamics of adult survival rate. Instead, dry and cold years led to low adult survival rates. Low juvenile survival rates, that limit recruitment of first-year breeders, and the regular occurrence of years with poor adult survival, were the most important determinants of the population decline of the little owl

ANALYSE D'UN MOTEUR ULTRASONORE PIÉZOÉLECTRIQUE À L'AIDE DE LA MODÉLISATION

Ultrasonic motors use a frictional force produced by high frequency vibrations created by the piezoelectric effect of the stator, to drive the rotor. These devices have been widely studied especially in Japan. A stator of a piezoelectric ultrasonic rotating motor, which uses Lamb waves vibrations, has been modelled using the finite element code ATILA. It takes into account three dimensional piezoelectric effects and electrical excitations. ATILA permits the computation of the resonance frequency and the effective coupling coefficient of each vibrational mode, the electrical impedance and the elliptical displacement field. The governing electromechanical coupling has been determined. Consequently, the selection of active material and stator geometry may be optimized to provide an improved transduction efficiency

Applications of piezoelectric actuators to precise and fast positioning tasks

Several classes of low-voltage Piezo Actuators have been developed by Cedrat Technologies in order to cover needs for Precise and/or Fast Positioning. This paper discusses of the ability for these Actuators to meet these needs and illustrates it with various applications (mechanisms, dampers, valves) in instrumentation, space, aircraft and automotive industries

The PICARD/SODISM Pointing Mechanism: From the Design to the Flight Performances

International audiencePICARD is a French space scientific mission. Its objectives are the study of the origin of the solar variability and the study of the relations between the Sun and the Earth's climate. The Satellite was successfully launched, on June 15, 2010 on a DNEPR launcher from Dombarovskiy Cosmodrome, near Yasny (Russia). The payload consists in two absolute radiometers measuring the total solar irradiance and an imaging telescope to determine the solar diameter and asphericity. SODISM (SOlar Diameter Imager and Surface Mapper) is a 11 cm Ritchey-Chretien imaging telescope associated with a CCD, taking solar images at five wavelengths. It carries a four-prism system to ensure a metrological control of the optics magnification. The first image of the Sun with this new instrument was taken on July 22, 2010. A mechanism of this instrument is the subject of the presentation. Current and future space telescope mission require ever-higher dimensionally stable structures. CNRS aims to design, manufacture and test a very high dimensional stability telescope for precision optical systems using advanced materials combining high dimensional stability and good structural performance. To achieve these accurate measurements, SODISM includes a fine pointing mechanism, based on the piezoelectric technology. This paper covers the description of the SODISM instrument, the design and the qualification of the pointing mechanism, and the flight results (commissioning phase and in orbit validation phase)

Mechanisms for space applications

International audienceAll space instruments contain mechanisms or moving mechanical assemblies that must move (sliding, rolling, rotating, or spinning) and their successful operation is usually mission-critical. Generally, mechanisms are not redundant and therefore represent potential single point failure modes. Several space missions have suffered anomalies or failures due to problems in applying space mechanisms technology. Mechanisms require a specific qualification through a dedicated test campaign. This paper covers the design, development, testing, production, and in-flight experience of the PICARD/SODISM mechanisms. PICARD is a space mission dedicated to the study of the Sun. The PICARD Satellite was successfully launched, on June 15, 2010 on a DNEPR launcher from Dombarovskiy Cosmodrome, near Yasny (Russia). SODISM (SOlar Diameter Imager and Surface Mapper) is a 11 cm Ritchey-Chretien imaging telescope, taking solar images at five wavelengths. SODISM uses several mechanisms (a system to unlock the door at the entrance of the instrument, a system to open/closed the door using a stepper motor, two filters wheels using a stepper motor, and a mechanical shutter). For the fine pointing, SODISM uses three piezoelectric devices acting on the primary mirror of the telescope. The success of the mission depends on the robustness of the mechanisms used and their life

Application des materiaux actifs nouveaux a l'electrotechnique

Available from INIST (FR), Document Supply Service, under shelf-number : AR 15720 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEMinistere de l'Education Nationale de l'Enseignement Superieur et= de la Recherche, 75 - Paris (France)FRFranc