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In this article, pinch-off voltage biasing was utilized for the first time to determine the average channel temperature of the AlGaN/GaN HEMT, which made it possible to exclude the device’s electrical parameters dependence in the linear operating mode. The theoretical part is focused on the thermal model with temperature-dependent thermal resistance utilization for active area average temperature determination of the HEMT under quasi-static operation. The experimental part deals with drain-to-source current comparison utilizing quasi-static and pinch-off voltage-biased short-pulse output ${I}$ – ${V}$ characteristics and additional isothermal trapping phenomena determined from the threshold voltage shift. The appropriate use and combination of methods for the active area average temperature determination utilizing constant isothermal saturation current or short-pulse current were discussed.

The modified thermal device model was adapted to determine the channel temperature of the AlGaN/GaN HEMT operating under pulsed and quasi-static conditions. The differential analysis of the isothermal and thermal part of the resulting current, as well as ambient temperature variation, is utilized to determine the average channel temperature. Ambient temperature increases in the device operating range is required under low-power operation only, while under high-power operation the thermal stress of the device is significantly reduced due to small ambient temperature variation. In addition, trapping phenomena incorporation is demonstrated to obtain more accurate results utilizing the HEMT threshold voltage shift and transconductance. For experimental verification of the thermal model, Al0.25Ga0.75N/GaN HEMT electrical properties are investigated. Experimentally verified results are in a good agreement with numerical simulations.

Cette étude propose, pour la première fois, une analyse de l'impact de la crise sanitaire sur le recours au SAMU. Elle s'appuie sur des données exhaustives de l'ensemble des SAMU, pour objectiver le recours accru au SAMU par la population, tant au niveau national que départemental, sur la période 2014-2021. Les données 2022 seront disponibles pour Emois.

Les études existantes sur le risque de développer des formes sévères de COVID-19, conduisant à une hospitalisation éventuellement suivie d'un décès ou d'une admission en soins critiques, analysent essentiellement les facteurs cliniques. Cette étude complète la littérature par l’étude des caractéristiques socio-économiques des patients hospitalisés atteints de COVID-19.

In situ NMR spin–lattice relaxation measurements were performed on several vapor deposited ices. The measurements, which span more than 6 orders of magnitude in relaxation times, show a complex spin–lattice relaxation pattern that is strongly dependent on the growth conditions of the sample. The relaxation patterns change from multitime scale relaxation for samples grown at temperatures below the amorphous–crystalline transition temperature to single exponential recovery for samples grown above the transition temperature. The slow-relaxation contribution seen in cold-grown samples exhibits a temperature dependence, and becomes even slower after the sample is annealed at 200 K. The fast-relaxation contribution seen in these samples, does not seem to change or disappear even when heating to temperatures where the sample is evaporated. The possibility that the fast relaxation component is linked to the microporous structures in amorphous ice samples is further examined using an environmental electron scanning microscope. The images reveal complex mesoscale microporous structures which maintain their morphology up to their desorption temperatures. These findings, support the possibility that water molecules at pore surfaces might be responsible for the fast-relaxation contribution. Furthermore, the results of this study indicate that the pore-collapse dynamics observed in the past in amorphous ices using other experimental techniques, might be effectively inhibited in samples which are grown by relatively fast vapor deposition.

We report on the photoresponse dependence on the terahertz radiation intensity in ALGaN/GaN HEMTs. We show that the ALGaN/GaN HEMT can be used as a THz detector in CW and in pulsed regime up to radiation intensity of several kW/cm2. The dynamic range in the pulsed regime of detection can be more than 2 decades. We observed that the photoresponse of the HEMT could have a compound composition if two independent parts of the transistor are involved in the detection process; this result indicates that a more simple one channel device may be preferable on the detection purpose.

La prise en compte des moteurs de ségrégation superficielle dans un modèle cinétique (KTBIM) permet de rendre compte des cinétiques de dépôt-dissolution observées expérimentalement. Nous nous proposons de mettre en évidence le comportement des premiers plans près de la surface dans le cas d'un dépôt de fer sur un substrat de cuivre : une (ou deux) couche(s) flottante(s) de cuivre apparaissent sur le dépôt de fer avant la dissolution de celui-ci, en très bon accord avec les observations expérimentales. Le concept d'équilibre local nous permet de faire le lien entre les profils de concentration observés lors de la cinétique de dissolution et les profils d'équilibre de la couche mince dite équivalente.

Nous avons poursuivi en région limousin une expérimentation de suivi des patients opérés par chirurgie bariatrique, faisant appel au téléphone mobile et au SMS, avec le support de l’Agence Régionale de Santé. Une série de patients consécutifs a été opérée de juillet à octobre 2010 et recrutée pour un suivi postopératoire du poids par SMS hebdomadaire. 33 patients (5 H, 28 F) ont eu une perte de poids moyenne de 28,7 kg, avec une durée moyenne de suivi de 70 semaines, et un nombre moyen de réponses SMS par mois de suivi et par patient de 3,5. Le taux final de réponses exploitables transmises par les patients a été de 96 %. Notre proposition de suivi par SMS initie et renforce le suivi postopératoire. Le téléphone mobile devient un moyen simple, peu onéreux et efficace dans ce suivi. La densité du suivi lors des premiers mois contribue à de meilleurs résultats de la chirurgie, notre proposition pourrait trouver un prolongement dans la création d’un « Bariatric Call Center ».

AlGaN/GaN based FETs have great potential as sensitive and fast operating detectors because of their material advantages such as high breakdown voltage, high electron mobility, and high saturation velocity. These advantages could be exploited for resonant and non-resonant terahertz detection. We have designed, fabricated, and characterized AlGaN/GaN based FETs as single pixel terahertz detectors. This work focuses on non-resonant detection and imaging using GaN field plate FETs. To evaluate their performances as terahertz detectors, we have measured the responsivity as a function of gate voltage, the azimuthal angle between the terahertz electric field, the source-to-drain direction, and the temperature. A simple analytical model of the response is developed. It is based on plasma density perturbation in the transistor channel by the incoming terahertz radiation. The model shows how the non-resonant detection signal is related to static (dc) transistor characteristics and it fully describes the experimental results on the non-resonant sub-terahertz detection by the AlGaN/GaN based FETs. The imaging performances are evaluated by scanning objects in transmission mode and an example of application of terahertz imaging as new non-destructive technique for the quality control of materials is given. Results indicate that these FETs can be considered as promising devices for terahertz detection and imaging applications.

High power RF device performance decreases as operation temperature increases (e.g. decreasing electron mobility affects cut-off frequencies and degrades device reliability). Therefore determination of device temperature is a key issue for device topology optimisation. In this work the temperature variation of AlGaN/GaN high-electron-mobility transistors grown either on silicon or sapphire substrate under bias operation was measured by micro Raman scattering spectroscopy. Temperature measurements up to power dissipation of 16 W for 4 mm development devices were carried out and a peak temperature of 650 K was determined. The difference of thermal resistance for similar devices grown on the two different substrates was assessed. The thermal resistances of different device topologies were compared to optimise the component design.

The high power RF device performance decreases as the operation temperature increases (e.g. fall of electron mobility impacting the cut-off frequencies and degradation of device reliability). Therefore the determination of device temperature is a key issue for device topology optimisation. In this work the temperature variation of AlGaN/GaN high-electron-mobility transistors grown either on silicon or sapphire substrates under bias operation was measured by micro Raman scattering spectroscopy. The differences in thermal resistance for similar devices grown on the two different substrates were assessed. The thermal resistances of different device topologies were compared in order to optimise the component design. The temperature measurement across the gate and along the component fingers were made to quantify the thermal gradient of the device. Temperature measurement up to a power dissipation of 16 W for a 4 mm development device was carried out and the peak temperature of 650 K was determined.

The high power RF device performance decreases as operation temperature increases (e.g.fall of electron mobility impacting the cut-off frequencies and degradation of device reliability). Therefore the determination of device temperature is a key issue for device topology optimisation. This work presents the comparison between pulsed I-Vat different temperature and DC measurements of AlGaN/GaN HEMTs grown on two different substrates: sapphire and silicon. This technique allows the determination of mean channel temperature and the device thermal resistance. The thermal resistance is a classical way to define the average channel temperature as a function of the dissipated power. In this work the thermal resistance ratio of the HEMT grown on sapphire compared to the one grown on silicon is found to be 1.7 instead of 3 as expected from straightforward thermal conductivity ratio. This lower difference is clearly attributed to the contribution of the GaN buffer layer.

The products of ras and src proto-oncogenes are frequently activated in a constitutive state in human colorectal cancer. In this study we attempted to establish whether the tumorigenic progression induced by oncogenic activation of p21ras and pp60c-src in human colonic Caco-2 cells is associated with specific alterations of syndecan-1, a membrane-anchored proteoglycan playing a role in cell-matrix interaction and neoplastic growth control. To this end, we used Caco-2 cells made highly tumorigenic by transfection with an activated (Val 12) human Ha-ras gene or with the polyoma middle T (Py-MT) oncogene, a constitutive activator of pp60c-src tyrosine kinase activity. Compared with control vector-transfected Caco-2 cells, both oncogene-transfected cell lines (1) contained smaller amounts of membrane-anchored PGs; (2) exhibited decreased syndecan-1 expression at the protein but not the mRNA level; (3) synthesized 35S-labelled syndecan-1 with decreased specific activity; (4) produced a syndecan-1 ectodomain with a lower molecular mass and reduced GAG chain size and sulphation; and (5) expressed heparanase degradative activity. These results show that the dramatic activation of the tumorigenic potential induced by oncogenic p21ras or Py-MT/pp60c-src in Caco-2 cells is associated with marked alterations of syndecan-1 expression at the translational and post-translational levels.

The energy distribution of grain-boundary states is determined for polycrystalline silicon films grown under ultra-high vacuum conditions. Conductivity and electron spin resonance measurements on n-type films reveal both exponential bandtails and deep gap states corresponding to disorder-induced gap states and dangling-bond defect levels (D° and D-). The latter are responsible for the pinning of the Fermi level observed at moderate doping. Both experimental techniques agree with a location of the D- level at EC-0.30 eV and the D° level at EC-0.65eV ± 0.05eV. It is shown that a hydrogen-plasma treatment at 500°C reduces the dangling-bond density by an order of magnitude and that it also yields a conduction bandtail twice as steep. The replacement of weak Si-Si bonds by more energetic Si-H bonds would explain the steeper bandtails. This view is supported by absolute measurements by nuclear reaction showing that the hydrogen content exceeds by two orders of magnitude the original dangling-bond density. A spin density as Iow as 5 × 1016cm-3 is measured for the first time in fine-grained polycrystalline silicon. The passivation of Si dangling bonds is accompanied by a shift of the pinned position of the Fermi level from 0.5 to 0.45 eV below EC, which could mean that the remaining deep defects have a slightly different energy distribution.

Epitaxial Si<111>/CoSi2/Si heterostructures have been grown using molecular beam epitaxy (MBE) apparatus with the overgrown Si layer doped by Sb coevaporation. Electrical characteristics of the top CoSi2/Si epitaxial Schottky barriers are presented. Current/voltage (I/V), capacitance/voltage (C/V) characteristics and deep level transient spectra (DLTS) show that the overgrown Si material is deviceworthy. Furthermore, transconductance measurements between the emitter and collector of the metal base transistor (MBT) indicate that the high Si quality is obtained with a negligible pinhole density in the base. Measurements of the current gain α in the MBT confirm a value of the CoSi2 ballistic mean free path of 90 A˚ ± 20 A˚.

Epitaxial Si 〈111〉/CoSi2/Si structures have been grown by molecular beam epitaxy. The transistor effect, via ballistic electron transport in the CoSi2 200 A˚-thick base, has been observed. The ballistic mean free path in CoSi2 obtained (λB ˜ 105 A˚) from the current gain is consistent within 20% with the predicted value (λBth ˜ 80 A˚).

The surface chemistry of InAlN ultra-thin layers, having undergone an oxidation procedure usually running through the HEMT fabrication process (850°C, O2and O2+Ar) is studied by XPS. The suitability of XPS analysis to operate as a retro-engineering tool for added value microelectronic devices fabrication is shown. A precise examination of the Al2p, In3d5/2, N1s, and O1s peaks directly informs about spatial and atomic arrangement. The formation of a covering 3 nm surface oxide is evidenced after O2annealing. Once annealed, two specific additional N1s contributions are shown, at higher (404.0 eV) and lower binding energies (397.4 eV) compared to the InAlN matrix one (396.5 eV). To our knowledge, such fingerprint is rather unusual for ternary III-V materials. It reveals the formation of a nitrogen deficient interlayer, situated between the oxide overlayer and the undisturbed matrix, and the presence of interstitial N2molecules trapped at the interface. After Ar annealing, both oxide and interface layers are partially reorganized. InAlN reactivity toward higher annealing temperature (950°C) and its stability over time is finally discussed. N2molecules are unstable and progressively eliminated in time although nitrogen deficient interlayer still remains. Thermal treatments below 850°C are recommended to preserve the barrier chemical integrity.

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Keywords: Montreal; Canada; North and Central America; Drugs and Therapies; Health and Medicine; Oncology EN Montreal Canada North and Central America Drugs and Therapies Health and Medicine Oncology 2023 MAR 13 (NewsRx) -- By a News Reporter-Staff News Editor at Clinical Oncology Week -- Researchers detail new data in Health and Medicine - Oncology. A Pilot Study On Brief Hypnotic Communication Training Conducted With Oncology Nurses) Montreal, Canada, North and Central America, Drugs and Therapies, Health and Medicine, Oncology. [Extracted from the article]

This paper presents a new type of transmission-line resonator and its application to RF (microwave and millimeter- wave) heterojunction bipolar transistor (HBT) oscillators. The resonator is a parallel combination of two open stubs having length of λ/4 ±δ 6(6 ⪡ λ), where λ is a wavelength at a resonant frequency. The most important feature of this resonator is that the coupling coefficient (ßc) can be controlled by changing δ while maintaining unloaded Q-factor (Qu) constant. Choosing a small value of δ allows us to reduce ßc or equivalently to increase loaded Q-factor (QL). Since coupling elements such as capacitors or electromagnetic gaps are not needed, ßc and QL can be precisely controlled based on mature lithography technology. This feature of the resonator proves useful in reducing phase noise and also in enhancing output power of microwave oscillators. The proposed resonator is applied to 18-GHz and 38-GHz HBT oscillators, leading to the phase noise of - 96-dBc/Hz at 100-kHz offset with 10.3-dBm output power (18-GHz oscillator) and - 104-dBc/Hz at 1-MHz offset with 11.9 dBm (38-GHz oscillator). These performances are comparable to or better than state-of-the-art values for GaAs- or InP-based planar-circuit fundamental-frequency oscillators at the same frequency bands. [ABSTRACT FROM AUTHOR]

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