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This paper presents the capacity of an S band circularly polarized patch antenna using a ferrite material for low-earth orbiting satellites (2025–2100 MHz for TeleCommand) to obtain a semi-isotropic radiation pattern. Indeed, circularly polarized antennas are generally large and bulky which is often incompatible for spatial applications especially for small satellites. A new antenna design is proposed with the following maximum dimensions: a diameter of 80 mm and a height of 12 mm. The structure presents an axial ratio lower than 6 dB (according to requirements) and a realized gain higher than −6 dB over a 4% bandwidth at the limit of coverage i.e. 90° irrespective of the azimuth angle (φ).
Spatial telemetry links on nanosatellites require more and more reconfigurable beam antennas to improve the Earth coverage. The bi-mode Agile Radiating Matrix Antenna (8.0–8.4 GHz) was successfully designed to solve such kind of problems by using an isoflux mode associated with a switchable directive one. However, such an antenna introduces some manufacturing problems for the isoflux mode, mainly due to the small available volume on the nanosatellite platform. This paper describes a solution to this problem thanks to the ARMA concept. A comparison between theoretical and experimental results for the isoflux mode in circular polarization is presented to validate the results.
Objectives: Neurofibromatosis type 1 (NF1) is a genetic disorder in which the most frequent complication in children is learning disabilities. Over the past decade, growing arguments support the idea that executive dysfunction is a core deficit in children with NF1. However, some data remain inconsistent. The aim of this study was to determine the magnitude of impairment for each executive function (EF) and clarify the impact of methodological choices and participant’s characteristics on EFs. Methods: In this meta-analysis, 19 studies met the selection criteria and were included with data from a total of 805 children with NF1 and 667 controls. Based on the Diamond’s model (2013), EF measures were coded separately according to the following EF components: working memory, inhibitory control, cognitive flexibility, planning/problem solving. The review protocol was registered with PROSPERO (International prospective register of systematic reviews; CRD42017068808). Results: A significant executive dysfunction in children with NF1 is demonstrated. Subgroup analysis showed that the impairment varied as a function of the specific component of executive functioning. The effect size for working memory and planning/problem solving was moderate whereas it was small for inhibitory control and cognitive flexibility. Executive dysfunction seems to be greater with increasing age whereas assessment tool type, intellectual performance, attention deficit hyperactivity disorder and control group composition did not seem to affect EF results. Conclusions: EF deficits are a core feature in children with NF1 and an early identification of executive dysfunctions is essential to limit their impact on the quality of life. (JINS, 2018, 24, 977–994)
Amorphous TiO2 and SnO2 electron transport layers (ETLs) were deposited by low-temperature atomic layer deposition (ALD). Surface morphology and x-ray photoelectron spectroscopy (XPS) indicate uniform and pinhole free coverage of these ALD hole blocking layers. Both mesoporous and planar perovskite solar cells were fabricated based on these thin films with aperture areas of 1.04 cm2 for TiO2 and 0.09 cm2 and 0.70 cm2 for SnO2. The resulting cell performance of 18.3 % power conversion efficiency (PCE) using planar SnO2 on 0.09 cm2 and 15.3 % PCE using mesoporous TiO2 on 1.04 cm2 active areas are discussed in conjunction with the significance of growth parameters and ETL composition.
The specific surface area (SSA), defined as the surface area of ice per unit mass, is an important variable characterizing the complex microstructure of snow. Its application range covers the physical evolution of snow (metamorphism), photochemistry and optical and microwave remote sensing. This paper presents a new device, POSSSUM (Profiler Of Snow Specific Surface area Using SWIR reflectance Measurement), designed to allow the rapid acquisition of SSA profiles down to ∼20 m depth and with an effective vertical resolution of 10–20 mm. POSSSUM is based on the infrared (IR) reflectance technique: A laser diode operating at 1310 nm illuminates the snow at nadir incidence angle along the face of a drilled hole. The reflected radiance is measured at three zenith angles (20°, 40° and 60°) each for two azimuth angles (0° and 180°). A second laser operating at a shorter wavelength (635 nm), which is almost insensitive to SSA, allows the distance to the snow face to be estimated. The reflected IR radiance and the distance are combined to estimate bidirectional reflectances. These reflectances are converted into hemispherical reflectances and in turn into SSA using a theoretical formulation based on an asymptotic solution of the radiative transfer equation. The evaluation and validation of POSSSUM’s SSA measurements took place in spring 2009 in the French Alps. The new method was compared with the methane adsorption technique and DUFISSS, another well-validated instrument based on the IR technique. The overall measurement error is in the range 10–15%.
We present spatial patterns of glacier fluctuations from the Cordillera Blanca, Peru, (glacier area, terminus elevations, median elevations and hypsography) at decadal timescales derived from 1970 aerial photography, 2003 SPOT5 satellite data, Geographic Information Systems (GIS) and statistical analyses. We derived new glacier outlines from the 2003 SPOT images, and ingested them in the Global Land and Ice Measurements from Space (GLIMS) glacier database. We examined changes in glacier area on the eastern and western side of the Cordillera in relation to topographic and climate variables (temperature and precipitation). Results include (1) an estimated glacierized area of 569.6 ± 21 km2 in 2003, (2) an overall loss in glacierized area of 22.4% from 1970 to 2003, (3) an average rise in glacier terminus elevations by 113 m and an average rise in the median elevation of glaciers by 66 m, showing a shift of ice to higher elevations, especially on the eastern side of the Cordillera, and (4) an increase in the number of glaciers, which indicates disintegration of ice bodies. Annual air temperature showed a significant upward trend in the last 30 years, with larger temperature increases at lower elevations. There was a slight but not significant decrease in precipitation. Our results are consistent with glacier retreat and warming trends noted in the last three decades in the tropics.
Background: The therapeutic value of second-generation anticonvulsants such as lamotrigine has not been clearly established in neonates and infants with seizures. To address this issue, we assessed the efficacy of lamotrigine for treating neonatal and infantile seizures, detailed the dosing regimens used, and described its tolerability and safety profile. Methods: This retrospective study included patients (age 0-12 months) diagnosed with seizures and treated with lamotrigine, as monotherapy or adjunctive therapy, by pediatric neurologists at Centre mère-enfant Soleil du CHUQ from 2004 to 2014. The frequency of seizures and EEG patterns were compared before and after introduction of lamotrigine during the first months of life. Data on initial and maintenance doses, rate and magnitude of dosing increments, and adverse effects were collected. Results: Treatment with lamotrigine was initiated in 32 neonates and 13 infants. At first follow-up (mean duration 3 months), 76 % (n = 34) showed a significant (≥50%) reduction of seizures and 64% (n= 29) improvement of EEG pattern compared to baseline. The efficacy in monotherapy and adjunctive therapy was similar. A single case of cutaneous hypersensitivity reaction requiring cessation of treatment was reported. Conclusions: This study suggests that lamotrigine is a useful, safe, and well-tolerated anticonvulsant alternative for the treatment of seizures in neonates and infants.
The BBXRT observed nine supernova remnants during its nine-day flight. We present preliminary results from some of these observations, emphasizing the ability of BBXRT to perform spatially resolved spectroscopy. The improved spectral resolution and efficiency over previous instruments makes possible measurements of previously undetectable lines, and the broad bandpass allows simultaneous measurement of lines from oxygen through iron.
First spatially resolved spectroscopic observations of the Virgo and Coma clusters made with XMM during the PV phase are presented. The implication for the dynamical state of these clusters are briefly discussed.
This paper focuses on the design of a telemetry antenna system intended for small satellites. It provides an axial ratio (AR) lower than 3 dB over ±60° conical space angle with over 20% of bandwidth. The antenna consists of a multilayer patch element fed by a wideband feeding circuit. The latter is an appropriate adjustment of 90° hybrid couplers and 180° ring coupler. We show that this design provides high-quality circular polarization properties for agile small satellites without having to suspend their mission to download their data and also without sacrificing the antenna low profile and wide bandwidth. The antenna is fabricated and the experimental performance is presented and followed by a discussion.
Epitaxial Si/CoSi2/Si structures can be grown under ultra-high vacuum conditions. The metallic CoSi2 films can be extremely thin typically between 1 nm and 20 nm. The electrical properties of these heterostructures are presented, mainly the transport of electrons in the metallic films parallel to the interfaces and the transfer of electrons through the metal ilm. The influence of pinholes in the CoSi2 layers will be discussed.
During the last 50 years, there has been a considerable amount of work for the elaboration of efficient luminescent materials, most of them dealing with the search for new chemical compositions. Only a very few studies have concerned the study of the influence of the microstructure of the materials on their properties of emission, especially when the grain sizes of the materials are in the nanometer range. On another side, important advances have been performed in colloid chemistry in the last years, especially in the case of II-VI chalcogenides, as a consequence on the intense activity around the physics of quantum confinement in semiconductors.
The basic idea of this work is to show that the techniques developed in the case of II-VI nanoparticles could find interesting applications for the elaboration of nanostructured luminescent materials. This is first illustrated in the case of pure CdS nanoparticles, whose properties are deeply affected by their surface state and their chemical environment. Incorporation of manganese in solid solution in the CdS particles drastically changes the emission process, which now essentially depends on the manganese content inside each particle. Finally, the extension of the synthesis process to rare earth doped oxide particles is presented, and the luminescence efficiency is discussed as a function of the size, the structure, and the chemical environment of the particles.
In this paper, we present CVD (Chemical Vapor Deposition) growth and passivation of tungsten (W) and titanium nitride (TiN) nanocrystals (NCs) on silicon dioxide and silicon nitride for use as charge trapping layer in floating gate memory devices. NCs are deposited in an 8 inches industrial CVD Centura tool. W and TiN are chosen for being compatible with MOSFET memory fabrication process. For protecting NCs from oxidation, a silicon shell is selectively deposited on them. Moreover, for a better passivation, TiN NCs are encapsulated in silicon nitride (Si3N4) in order to get rid of oxidation issues. After high temperature annealing (1050°C under N2 during 1 minute) XPS measurements point out that NCs are still metallic, which makes them good candidates for being used as charge trapping layer in floating gate memories.
This paper presents a lake-level record established for the last millennium at Lake Saint-Point in the French Jura Mountains. A comparison of this lake-level record with a solar irradiance record supports the hypothesis of a solar forcing of variations in the hydrological cycle linked to climatic oscillations over the last millennium in west-central Europe, with higher lake levels during the solar minimums of Oort (around AD 1060), Wolf (around AD 1320), Spörer (around AD 1450), Maunder (around AD 1690), and Dalton (around AD 1820). Further comparisons of the Saint-Point record with the fluctuations of the Great Aletsch Glacier (Swiss Alps) and a record of Rhône River floods from Lake Bourget (French Alps) give evidence of possible imprints of proxy sensitivity on reconstructed paleohydrological records. In particular, the Great Aletsch record shows an increasing glacier mass from AD 1350 to 1850, suggesting a cumulative effect of the Little Ice Age cooling and/or a possible reflection of a millennial-scale general cooling until the mid-19th century in the Northern Hemisphere. In contrast, the Saint-Point and Bourget records show a general trend toward a decrease in lake levels and in flood magnitude anti-correlated with generally increasing solar irradiance.
High carbon and chromium martensitic stainless steels are used when hardness
and corrosion resistance are essential. Their mechanical properties and cold
workability are impaired by large Cr carbides formed during solidification.
This can be overcome by a nitrogen addition as a substitute for high carbon.
Results are reported about 0.080% N addition to a 1.4116 grade
(C=0.47%, Cr=14.5%, Mo=0.5%). The new grade offers a better combination
of hardness, toughness and corrosion resistance than the three higher carbon
grades 1.4109, 1.4112 or 1.4125.
Within the framework of the Water Management Master plan, a bioindicator network (RINBIO) was deployed all along the French Mediterranean coast (1,800 km), using man-made cages containing mussels (Mytilus galloprovincialis) to assess contamination by heavy metals, persistent organic products and radionuclides. The caging technique compensated for the scarcity of natural shellfish stocks in significant parts of the coast and enable comparison between sites regardless of their physicochemical and trophic characteristics. Among the 103 stations of the entire program, 40 were selected for the measurement of anthropogenic radionuclides by high-efficiency gamma-spectrometry. Biometrics parameters of the each mussel samples, including `condition index' as an indicator of soft part growth, is correlated with radionuclides activities, to help correct raw data from differences in bioaccumulation between the various sites in relation to their trophic levels. A comprehensive picture of the distribution of radionuclides at such a large spatial scale is provided and the contribution of the Rhone River input, so far the main source for the coastal zone, is investigated.