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)

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

Citotoxicity of capsaicin in monkey kidney cells: lack of antagonistic effects of capsazepine and Ruthenium red

Capsaicin is a natural product of Capsicum peppers, excitatory effects of which have been shown to be mediated by the recently cloned vanilloid receptor 1 (VR1). Since previous studies have shown that capsaicin inhibits protein synthesis, experiments were performed to investigate whether this effect is mediated by VR1 receptor on cultured monkey kidney cells (Vero cells). The capsaicin uptake was assessed in cellular homogenate and in medium by high-performance liquid chromatography (HPLC) separation and quantification on C18 reverse-phase column and fluorescence detection. Toxic effects were assessed by incorporation of [3H]L-leucine into cellular proteins in the presence of capsazepine, the VR1 vanilloid receptor antagonist and Ruthenium red or tyrosine or calcium. Capsazepine (1 to 256 microM) did not modify the uptake rate of capsaicin for incubation times up to 24 h and did not antagonize capsaicin-induced protein synthesis inhibition. It rather inhibited protein synthesis per se from 100 to 256 microM. Ruthenium red which blocks mitochondrial calcium uptake, inhibited protein synthesis and did not antagonise or increase synergistically the effects of capsaicin. Interestingly in a medium deprived of calcium and supplemented by calcium chloride (10-50 microM) the protein synthesis inhibition induced by capsaicin is antagonised somehow. There was no prevention of capsaicin diffusion into the cells. Tyrosine, which seems to be the best preventive agent of capsaicin inhibitory effects, prevents its metabolism but not its diffusion. Capsaicin might enter cells by diffusion and interfere with protein synthesis machinery by competition with tyrosine which in turn prevents the metabolism of capsaicin. The results of the present study suggest that cell responses to capsaicin may be transduced through at least two molecular pathways, one involving VR1, since the receptor antagonist capsazepine fails to prevent the inhibitory effect of capsaicin in Vero cells of renal origin

Seasonal variations in the diet and food selection of the Algerian hedgehog Atelerix algirus

International audienceThe Algerian hedgehog Atelerix algirus is an insectivorous species. However, the exact composition of its naturaldiet remains largely undetermined, especially in relation to seasonal variations in food availability. From Marchto November, we simultaneously analysed the composition of 180 hedgehog faecal samples and food availabilityin the Soumman Valley, Algeria to assess food selection in this species. The faeces contained 196 differentprey species, of which 92% belonged to the class Insecta. The highest prey species diversity was found in theColeoptera order (100 species recorded) and the highest species occurrence was found in Hymenoptera (65% of theprey items, mainly represented by the harvester ant Messor barbarus, a crop-ravaging species). This study showsthat the Algerian hedgehog is mainly a generalist species with a diet that is strongly linked to food availability.However, seasonal variations were observed in prey selection, and a notable shift in food preference was observedduring autumn. The exact nature of these changes in feeding behaviour remains to be investigated, notably inrelation to changes in energy requirements of this species before hibernation, in terms of quantity and/or quality