Electrically tunable sign of capacitance in planar W-doped vanadium dioxide micro-switches.

Negative capacitance (NC) in a planar W-doped VO2 micro-switch was observed at room temperature in the low-frequency range 1 kHz-10 MHz. The capacitance changed from positive to negative values as the W-doped VO2 active layer switched from semiconducting to metallic state under applied voltage. In addition, a capacitance-voltage hysteresis was observed as the applied voltage was cycled from -35 to 35 V. These observations suggest that NC results from the increase of the electrically induced conductivity in the active layer. This NC phenomenon could be exploited in advanced multifunctional devices including ultrafast switches, field-effect transistors and memcapacitive systems.

[Epidemiological profile and chronological tendencies of the multiparity in the sanitary district of Monastir (Tunisia) between 1994 and 2003]. / Profil epidemiologique et tendances chronologiques de la multiparite dans le district sanitaire de Monastir (Tunisie) entre 1994 et 2003.

BACKGROUND: Multiparity, risk factor of maternal and foetal morbidity and mortality, is a worldwide public health problem. In Tunisia, in spite of the activities of the national program of maternal and infantile health implanted since 1966, the multiparity is yet observed in some regions of our country. Our objective is to draw up the epidemiological profile of the multipara woman (parity<6) and the grand multipara (parity> or =6) in the sanitary district of Monastir and to study the chronological tendencies of the factors associated during a decade (from 1994 to 2003). METHODS: In all, 16649 multipara were studied, representing 24% of the total women admitted for childbirth in the public motherhoods of the district. The global means age was 33,3 +/- 4,5 years with a statistical significance between multipara and grand multipara (32,7 and 35,6 respectively). The prenatal follow up was absent or inadequate for 50,2% of multipara and 62,8% of the grand multipara (p <0,001). RESULTS: In the decade, the main chronological tendencies are similar in the two multipara groups. Their frequency decreased from 28,5 to 19% (p<0,001), yet the age and the adequate follow up increased from 32,6 to 34 years and from 37,4 to 57,9% respectively (p<0,001). CONCLUSION: Although the multiparity is decreasing and its associated factors seem to improve, the vigilance is asked again in order to avoid the inherent risks.