Design and Modeling of Micromechanical GaAs based Hot Plate for Gas Sensors

For modern Gas sensors, high sensitivity and low power are expected. This paper discusses design, simulation and fabrication of new Micromachined Thermal Converters (MTCs) based on GaAs developed for Gas sensors. Metal oxide gas sensors generally work in high temperature mode that is required for chemical reactions to be performed between molecules of the specified gas and the surface of sensing material. There is a low power consumption required to obtain the operation temperatures in the range of 200 to 500 oC. High thermal isolation of these devices solves consumption problem and can be made by designing of free standing micromechanical hot plates. Mechanical stability and a fast thermal response are especially significant parameters that can not be neglected. These characteristics can be achieved with new concept of GaAs thermal converter.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/EDA-Publishing

Plasmons in Sodium under Pressure: Increasing Departure from Nearly-Free-Electron Behavior

We have measured plasmon energies in Na under high pressure up to 43 GPa using inelastic x-ray scattering (IXS). The momentum-resolved results show clear deviations, growing with increasing pressure, from the predictions for a nearly-free electron metal. Plasmon energy calculations based on first-principles electronic band structures and a quasi-classical plasmon model allow us to identify a pressure-induced increase in the electron-ion interaction and associated changes in the electronic band structure as the origin of these deviations, rather than effects of exchange and correlation. Additional IXS results obtained for K and Rb are addressed briefly.Comment: 5 pages, 4 figure

Angiogenesis-Related Factors in Early Pregnancy Loss

The habitual loss of early pregnancy is one of the major problems of obstetrics nowadays, provided that the cause of more than 50% of all early pregnancy losses is unknown. Adequate angiogenesis is one of the main indicators of proper formation of placental system, making the basis of fetal life support. The objective description of angiogenesis in physiological development of pregnancy and in pathological conditions is complicated by the difficulties in obtaining and characterizing placental tissue in early pregnancy. Thus, angiogenesis‐related factors are promising indicators to characterize angiogenesis in pregnancy. This chapter draws attention to alteration in angiogenesis‐related factors in peripheral blood of patients with habitual early pregnancy losses. Investigation of factors (vascular endothelial growth factor (VEGF), sFlt‐1, sKDR, metalloproteinase (MMP)‐2, MMP‐9, tissue inhibitor (TIMP)‐1, TIMP‐2 and placental growth factor (PLGF)), which specifically and nonspecifically regulate angiogenesis in pregnancy, was performed in the most significant terms for placentogenesis: 6 weeks, 7–8 weeks and 11–14 weeks of pregnancy. It was found that in a missed abortion there was a significant imbalance of angiogenesis‐related factors compared with normal pregnancy. These results reflect a disturbance of angiogenesis in a missed abortion and point to the importance of the studied factors in the pathogenesis of early pregnancy losses

Multi-site campaign for transit timing variations of WASP-12 b: possible detection of a long-period signal of planetary origin

The transiting planet WASP-12 b was identified as a potential target for transit timing studies because a departure from a linear ephemeris was reported in the literature. Such deviations could be caused by an additional planet in the system. We attempt to confirm the existence of claimed variations in transit timing and interpret its origin. We organised a multi-site campaign to observe transits by WASP-12 b in three observing seasons, using 0.5-2.6-metre telescopes. We obtained 61 transit light curves, many of them with sub-millimagnitude precision. The simultaneous analysis of the best-quality datasets allowed us to obtain refined system parameters, which agree with values reported in previous studies. The residuals versus a linear ephemeris reveal a possible periodic signal that may be approximated by a sinusoid with an amplitude of 0.00068+/-0.00013 d and period of 500+/-20 orbital periods of WASP-12 b. The joint analysis of timing data and published radial velocity measurements results in a two-planet model which better explains observations than single-planet scenarios. We hypothesize that WASP-12 b might be not the only planet in the system and there might be the additional 0.1 M_Jup body on a 3.6-d eccentric orbit. A dynamical analysis indicates that the proposed two-planet system is stable over long timescales.Comment: Accepted for publication in A&