Les terminaux de télécommunication face à l’environnement radioélectrique

This paper presents the work being carried out in the Emc field for the new telecommunication terminals so that the french telecommunications network should not be disturbed and a good service quality could be maintained even in presence of high level radio frequency ambients.     

Microsatellite instability in European hepatocellular carcinoma

A radioimmunoassay has been established to measure urinary aquaporin-2 excretion (u-AQP2). To elucidate how u-AQP2 changes when endogenous vasopressin is increased independently of plasma osmolality, we estimated u-AQP2 during general anesthesia for surgery. We collected urine and blood samples from 50 patients before and 90 and 180 min after anesthetic induction. Plasma (29.1+/-12.6 pg/mL) and urinary (565.1+/-207.0 ng/gCr) vasopressin levels were markedly increased after anesthetic induction. Although no significant alteration of plasma osmolality or serum sodium concentration was observed during 180 min, u-AQP2 was significantly increased (preinduction 224.5+/-24.2 fmol/ mgCr; 90 min 243.3+/-31.8; 180 min 331.4+/-45.9), paralleling an increase of plasma and urinary vasopressin. The plasma vasopressin concentration after anesthetic induction was far in excess of that expected based on plasma osmolality. Individual plasma and urinary vasopressin concentrations correlated significantly with u-AQP2. At 180 min after anesthesia, plasma osmolality did not change, but urine osmolality decreased despite increased u-AQP2, and a preanesthetic positive correlation between urine osmolality and u-AQP2 disappeared. Thus, although u-AQP2 correlates with increased intrinsic vasopressin levels, the increase in u-AQP2 did not directly contribute to urine concentration. Apparently, an escape from the physiologic effects of high vasopressin level occurs during anesthesia via a mechanism independent of aquaporin-2. We conclude that the anesthetic would interfere with the urinary concentrating capacity at the level of AQP2-action. IMPLICATIONS: The excessive increase of intrinsic vasopressin exactly augmented urinary aquaporin-2 excretion, resulting in urine concentration; however, anesthesia seemed to modify this process possibly by interfering with the aquaporin-2 action.     

Field enhancement and apertureless near-field optical spectroscopy of single molecules

We report on fluorescence enhancement in near field optical spectroscopy by apertureless microscopy. Our apertureless microscope is designed around a confocal fluorescence microscope associated with an AFM head. First, we show that the confocal microscope alone allows single molecule imaging and single molecule fluorescence analysis. When associated with the AFM head, we demonstrate, for the first time to our knowledge, that single molecule fluorescence is enhanced under the silicon tip. We tentatively attribute this effect to field enhancement under the tip.     

Analysis of Dual-Band Helical Antenna for Diversity on Mobile Phones

Antenna diversity on a mobile phone is considered using two dual-band, GSM900/1800, helical antennas. The received signals in mobile Rayleigh fading channel are modeled using a new field simulation technique that involves the three-dimensional (3D) radiation pattern of antennas, 3D angle of arrivals (AoAs) and Doppler frequency. Statistical tools prove the validity of the field simulator. The signals correlation coefficient and diversity gain are computed for different mobile propagation environments by considering AoAs. It is shown that the diversity gain is slightly influenced by the environment models. The experimental prototype is developed and measured. Antenna characteristics: return loss, coupling, 3-D radiation patterns and antenna efficiency are obtained by the measurements and simulations. The diversity performance of the array configuration is measured in the rich wave scattering environment of a reverberation chamber (RC). Results including: signals correlation coefficient, average power of diversity branches, apparent/effective diversity gain and antenna efficiency in RC are provided. The influence of the mobile user is measured as well. Diversity gain of the helical array in both operating frequencies is fairly good. The signals correlation with user’s head increases in GSM900 and slightly decreases in GSM1800. In the former band, the diversity gain loss due to imbalance branch powers is found more important than in the later.

Aperture averaging of the two-wavelength intensity covariance function in atmospheric turbulence

The influence of aperture averaging on the two-wavelength intensity covariance function was experimentally determined for visible (0.63 microm) and infrared (1.06 microm) collinear, approximately spherical beams which propagated through the earth's turbulent atmosphere. Range varied from 1300 to 3250 m, and due to the prevailing atmospheric conditions, most measurements were made in the strong turbulence regimes. Results show that (1) the covariance function monotonically decreases as the receiver aperture size increases; (2) the correlation coefficient attains high values > or = 0.7) even for a relatively small aperture size of 5 mm; (3) while the single wavelength probability distribution of the intensity is approximately lognormal, the experimental two-wavelength conditional probabilities are higher than those predicted by the lognormal model.     

Organic Upconversion Imager with Dual Electronic and Optical Readouts for Shortwave Infrared Light Detection

There remains a critical need for large-area imaging technologies that operate in the shortwave infrared spectral region. Upconversion imagers that combine photo-sensing and display in a compact structure are attractive since they avoid the costly and complex process of pixilation. However, upconversion device research is primarily focused on the optical output, while electronic signals from the imager remain underutilized. Here, an organic upconversion imager that is efficient in both optical and electronic readouts, extending the capability of human and machine vision to 1400 nm, is designed and demonstrated. The imager structure incorporates interfacial layers to suppress non-radiative recombination and provide enhanced optical upconversion efficiency and electronic detectivity. The photoresponse is comparable to state-of-the-art organic infrared photodiodes exhibiting a high external quantum efficiency of ≤35% at a low bias of ≤3 V and 3 dB bandwidth of 10 kHz. The large active area of 2 cm² enables demonstrations such as object inspection, imaging through smog, and concurrent recording of blood vessel location and blood flow pulses. These examples showcase the potential of the authors’ dual-readout imager to directly upconvert infrared light for human visual perception and simultaneously yield electronic signals for automated monitoring applications.