Passive Covert Radars using CP-OFDM SFN. Reference signal recovery from blind beamforming

A passive Coherent Location (PCL) system uses the signal transmitted by so called illuminators-of-opportunity in the environment for the illumination of targets. It is then necessary to recover the original transmitted signal to be compared to the targets echoes. With CP-OFDM transmissions, it is quite easy to recover the original data and then to reconstruct the original transmission. But in the case of a Single Frequency Network , characterized by the presence of several transmitters using the same carrier frequency to broadcast the same signal, it is necessary to use directional sensors or spatial filter. In this paper, we propose two blind solutions : classical beamforming and CAPON filtering. Results of real measurements are presented

Avant-propos

Depuis la fin du XXe siècle, en France comme dans le monde anglo-saxon, les études littéraires et esthétiques se sont globalement tournées vers les questions éthiques et politiques. C’est dans ce mouvement que ce numéro d’Essais, consacré à la Politicité de la littérature et des arts contemporains, veut se situer. Il prolonge des interrogations nées au tournant du siècle dernier et s’applique à étudier un corpus formé dans les mêmes années, issu des mêmes préoccupations. S’il faut indiquer un..

Aldosterone increases T-type calcium channel expression and in vitro beating frequency in neonatal rat cardiomyocytes

Objective: Although aldosterone has been implicated in the pathogenesis of cardiac hypertrophy and heart failure, its cellular mechanism of action on cardiomyocyte function is not yet completely elucidated. This study was designed to investigate the effect of aldosterone on calcium channel expression and cardiomyocyte contraction frequency. Methods: Cultured neonatal rat ventricular cardiomyocytes were stimulated in vitro with 1 μmol/L aldosterone for 24 h. Calcium currents were then measured with the patch clamp technique, while calcium channel expression was assessed by real-time RT-PCR. Results: In the present study, we show that aldosterone increases Ca2+ currents by inducing channel expression. Indeed, aldosterone led to a substantial increase of L- and T-type Ca2+ current amplitudes, and we found a concomitant 55% increase of the mRNA coding for α1C and β2 subunits of cardiac L channels. Although T-type currents were relatively small under control conditions, they increased 4-fold and T channel α1H isoform expression rose in the same proportion after aldosterone treatment. Because T channels have been implicated in the modulation of membrane electrical activity, we investigated whether aldosterone affects the beating frequency of isolated cardiomyocytes. In fact, aldosterone dose-dependently increased the spontaneous beating frequency more than 4-fold. This effect of aldosterone was prevented by actinomycin D and spironolactone and reduced by RU486, suggesting a mixed mineralocorticoid/glucocorticoid receptor-dependent transcriptional mechanism. Moreover, inhibition of T currents with Ni2+ or mibefradil significantly reduced beating frequency towards control values, while conditions affecting L-type currents completely blocked contractions. Conclusion: Aldosterone modulates the expression of cardiac voltage-operated Ca2+ channels and accelerates beating in cultured neonatal rat ventricular myocytes. This chronotropic action of aldosterone appears to be linked to increased T channel activity and could contribute to the deleterious effect of an excess of this steroid in vivo on cardiac functio

Hiding or hospitalising? On dilemmas of pregnancy management in East Cameroon

Current international debates and policies on safe motherhood mainly propose biomedical interventions to reduce the risks during pregnancy and delivery. Yet, the conceptualisations of risk that underlie this framework may not correspond with local perceptions of reproductive dangers; consequently, hospital services may remain underutilised. Inspired by a growing body of anthropological literature exploring local fertility-related fears, and drawing on 15 months of fieldwork, this paper describes ideas about risky reproduction and practices of pregnancy protection in a Cameroonian village. It shows that social and supernatural threats to fertility are deemed more significant than the physical threats of fertility stressed at the (inter)national level. To protect their pregnancies from those social and supernatural influences, however, women take very physical measures. It is in this respect that biomedical interventions, physical in their very nature, do connect to local methods of pregnancy management. Furthermore, some pregnant women purposefully deploy hospital care in an attempt to reduce relational uncertainties. Explicit attention to the intersections of the social and the physical, and of the supernatural and the biomedical, furthers anthropological knowledge on fertility management and offers a starting point for more culturally sensitive safe motherhood interventions

Lecture de « l'ombre » ("Les rayons et les ombres", XXXIII)

Barrère Jean-Bertrand. Lecture de « l'ombre » ("Les rayons et les ombres", XXXIII). In: Cahiers de l'Association internationale des études francaises, 1986, n°38. pp. 257-265

Passive Covert Radars using CP-OFDM signals. A new efficient method to extract targets echoes

Passive Coherent Location (PCL) systems use the signal transmitted by so called illuminators-of-opportunity in the environment to illuminates the targets. With CP-OFDM transmissions, it is quite easy to recover the original data and then to reconstruct the original transmission. The main difficulty is to extract, from the mixture received on the sensors, only the targets echoes. A new efficient and low complexity method is exposed here. Results on both simulated and real data are presented

Hugo et le chèvre-pied

Barrère Jean-Bertrand. Hugo et le chèvre-pied. In: Cahiers de l'Association internationale des études francaises, 1958, n°10. pp. 121-137

Une science impériale pour l'Afrique ?

C'est un livre passionnant qui, dans sa forme de thèse, peut apparaître quelque peu ardu pour un lecteur non familier des productions de l' Ehess . Mais la présence de nombreuses citations de broussards, d'enquêteurs ethnographiques ou d'anthropologues coloniaux vient heureusement agrémenter cette « étude systématique des pratiques et des institutions scientifiques en Afrique française et à propos de l'Afrique française ». Il s'agit également d'un ..

Variantes du manuscrit de « Nouvelles morts d'Elpénor »

Barrère Jean-Bertrand. Variantes du manuscrit de « Nouvelles morts d'Elpénor ». In: Bulletin de l'Association Guillaume Budé, n°3, octobre 1978. pp. 287-303

Hugo (Victor), Ruy Blas

Barrère J.-B. Hugo (Victor), Ruy Blas. In: Revue belge de philologie et d'histoire, tome 51, fasc. 2, 1973. Histoire (depuis l'Antiquité) — Geschiedenis (sedert de Oudheid) pp. 412-413