Activity rhythms of hibernating hedgehogs

The body temperature (Tb) of both male and female hedgehogs living under natural climatic conditions was measured during the whole hibernation period (September to March). Three successive phases were distinguished: (1) the pre-hibernation phase (September-October) was characterized by short spontaneous hypothermic bouts; (2) the hibernation phase (from the end of October onwards) showed an alternation of long deep torpor bouts (up to 10 days in males and 14 days in females) and short spontaneous arousals (6 to 72 hours); (3) the final phase corresponded to the last arousal and occurred earlier in males (January-February) than in females (end of February-beginning of March

Rythmes d'activité chez le hérisson au cours de l'hibernation

The body temperature (Tb) of both male and female hedgehogs living under natural climatic conditions was measured during the whole hibernation period (September to March). Three successive phases were distinguished : (1) the pre-hibernation phase (September-October) was characterized by short spontaneous hypothermic bouts ; (2) the hibernation phase (from the end of October onwards) showed an alternation of long deep torpor bouts (up to 10 days in males and 14 days in females) and short spontaneous arousals (6 to 72 hours) ; (3) the final phase corresponded to the last arousal and occurred earlier in males (January-February) than in females (end of February-beginning of March). Tb was shown to vary with Ta. Concerning the light-dark cycles, the entries in torpor occurred more often at night (75 %) and the arousals in the day-time (73 %). The analysis of food consumption emphasized that hedgehogs still fed during the pre-hibernation phase, fasted during the hibernation phase, and fed again regularly from the last arousal. These results were related to energetics of hibernation as hedgehogs spent about 80 % of their time in hypothermia (= energy economy) and 20 % only in euthermia (= energy expenditure corresponding to body mass loss).Vignault M.-P., Saboureau M. Rythmes d'activité chez le hérisson au cours de l'hibernation. In: Revue d'Écologie (La Terre et La Vie), tome 48, n°2, 1993. pp. 109-119

The reproductive cycle in the male hedgehog (Erinaceus europaeus L.) : a study of endocrine and exocrine testicular functions

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A 1-Watt Ku-band Power Amplifier MMIC using Cost-effective Organic SMD Package

This paper presents the design and performance of a compact 1-Watt Ku-band power amplifier MMIC implemented in a novel microwave organic power package, compatible with SMD assembly lines. Due to the use of simple materials, like RO4003 substrate and copper, it allows significant cost reduction for RF module assembly. The packaged amplifier MMIC demonstrates as well, very high-gain, as high as 32 dB at Ku-band, under very stable conditions, and more than 1.25-Watt continuous-wave output power (>31 dBm)

An attempt to correlate brain areas containing melatonin-binding sites with rhythmic functions: a study in five hibernator species

High affinity melatonin-binding sites have been described, by means of autoradiography with 2-125I-melatonin as the ligand, in more than 60 brain areas of about 20 mammalian species, with dramatic variations in the nature and number of labelled structures among the different species studied. As melatonin is involved in the synchronization of biological rhythms, we have tried to correlate the brain areas containing melatonin-binding sites with some rhythmic functions typical of given species. Therefore, we have studied the location of melatonin-binding sites in the complete brain of five long-day breeders with hibernation cycles, viz. one insectivore and four rodents. With the exception of the suprachiasmatic nuclei and the pars tuberalis of the pituitary, both of which contain binding sites in all five species, few reactive structures are common, even among species from the same family, e.g. the edible dormouse and the garden dormous

Phenotypic and functional changes in regenerated porcine coronary endothelial cells: Increased uptake of modified LDL and reduced production of NO

Porcine coronary arteries with regenerated endothelium exhibit impaired endothelium-dependent relaxations. Experiments were designed to analyze the structural and functional changes occurring in regenerated endothelial cells. Primary cultures from regenerated endothelium contained giant endothelial cells, with an increased number of cells with diameter > 14.5 μm, a reduced ability to proliferate, and signs of apoptosis. The uptake of fluorescent acetylated LDL was increased 2-fold in cultures from regenerated endothelium. The increased uptake of acetylated LDL was confirmed ex vivo in injured coronary arteries. In cultures from regenerated endothelium, cGMP production was decreased under basal conditions and during stimulation with serotonin, bradykinin, and A23187. Thus, during regeneration, there is accelerated senescence of endothelial cells accompanied by increased incorporation of modified LDL and reduction of NO production without decrease in endothelial NO synthase expression. These alterations help to explain the altered endothelium-dependent responses 28 days after balloon injury.link_to_subscribed_fulltex

A New Multi-Harmonic Volterra Model dedicated to GaN Packaged Transistor or SSPA for Pulse Application

International audienceThis paper presents a new macro modeling methodology for solid-state amplifiers (SSAs) and packaged transistors used in radar systems. The model topology is based on the principle of the harmonic superposition recently introduced by the Agilent X-parameters(TM) combined with dynamic Volterra theory. In this work, we focus on a pulsed identification method which has been made from time domain load pull measurement performed on a packaged transistor. The model has been validated by pulsed RF measurement in the optimum area for several frequencies