In situ spectroellipsometric study of the nucleation and growth of amorphous silicon

A detailed in situ spectroellipsometric analysis of the nucleation and growth of hydrogenated amorphous silicon (a:Si:H) is presented. Photoelectronic quality a‐Si:H films are deposited by plasma‐enhanced chemical vapor deposition on smooth metal (NiCr alloy) and crystalline silicon (c‐Si) substrates. The deposition of a‐Si:H is analyzed from the first monolayer up to a final thickness of 1.2 μm. In order to perform an improved analysis, real time ellipsometric trajectories are recorded, using fixed preparation conditions, at various photon energies ranging from 2.2 to 3.6 eV. The advantage of using such a spectroscopic experimental procedure is underlined. New insights into the nucleation and growth mechanisms of a‐Si:H are obtained. The nucleation mechanism on metal and c‐Si substrates is very accurately described assuming a columnar microstructural development during the early stage of the growth. Then, as a consequence of the incomplete coalescence of the initial nuclei, a surface roughness at the 10-15 Å scale is identified during the further growth of a‐Si:H on both substrates. The bulk a‐Si:H grows homogeneously beneath the surface roughness. Finally, an increase of the surface roughness is evidenced during the long term growth of a‐Si:H. However, the nature of the substrate influenced the film growth. In particular, the film thickness involved in the nucleation‐coalescence phase is found lower in the case of c‐Si (67±8 Å) as compared to NiCr (118±22 Å). Likewise films deposited on c‐Si present a smaller surface roughness even if thick samples are considered (>1 μm). More generally, the present study illustrates the capability of in situ spectroellipsometry to precisely analyze fundamental processes in thin‐film growth, but also to monitor the preparation of complex structures on a few monolayers scale

SCUBA divers as oceanographic samplers: The potential of dive computers to augment aquatic temperature monitoring

Monitoring temperature of aquatic waters is of great importance, with modelled, satellite and in-situ data providing invaluable insights into long-term environmental change. However, there is often a lack of depth-resolved temperature measurements. Recreational dive computers routinely record temperature and depth, so could provide an alternate and highly novel source of oceanographic information to fill this data gap. In this study, a citizen science approach was used to obtain over 7,000 scuba diver temperature profiles. The accuracy, offset and lag of temperature records was assessed by comparing dive computers with scientific conductivity-temperature-depth instruments and existing surface temperature data. Our results show that, with processing, dive computers can provide a useful and novel tool with which to augment existing monitoring systems all over the globe, but especially in under-sampled or highly changeable coastal environments

Steric and mass-induced sea level variations in the Mediterranean Sea revisited

The total sea level variation (SLV) is the combination of steric and mass␣induced SLV, whose exact shares are key to understanding the oceanic response to climate system changes. Total SLV can be observed by radar altimetry satellites such as TOPEX/POSEIDON and Jason 1/2. The steric SLV can be computed through temperature and salinity profiles from in situ measurements or from ocean general circulation models (OGCM), which can assimilate the said observations. The mass-induced SLV can be estimated from its time-variable gravity (TVG) signals. We revisit this problem in the Mediterranean Sea estimating the observed, steric, and mass-induced SLV, for the latter we analyze the latest TVG data set from the GRACE (Gravity Recovery and Climate Experiment) satellite mission launched in 2002, which is 3.5 times longer than in previous studies, with the application of a two-stage anisotropic filter to reduce the noise in high-degree and -order spherical harmonic coefficients. We confirm that the intra-annual total SLV are only produced by water mass changes, a fact explained in the literature as a result of the wind field around the Gibraltar Strait. The steric SLV estimated from the residual of “altimetry minus GRACE” agrees in phase with that estimated from OGCMs and in situ measurements, although showing a higher amplitude. The net water fluxes through both the straits of Gibraltar and Sicily have also been estimated accordingly.This work was elaborated during the stay of the first author at the National Central University of Taiwan, thanks to a grant from the Generalitat Valenciana, Spain. Jean-Paul Boy is currently visiting NASA Goddard Space Flight Center, with a Marie Curie International Outgoing Fellowship (PIOF-GA-2008-221753). This work was partly funded by two Spanish projects from MICIN, ESP2006-11357, and AYA2009-07981 and one from Generalitat Valenciana (ACOMP2009/031)

COMMD1-Mediated Ubiquitination Regulates CFTR Trafficking

The CFTR (cystic fibrosis transmembrane conductance regulator) protein is a large polytopic protein whose biogenesis is inefficient. To better understand the regulation of CFTR processing and trafficking, we conducted a genetic screen that identified COMMD1 as a new CFTR partner. COMMD1 is a protein associated with multiple cellular pathways, including the regulation of hepatic copper excretion, sodium uptake through interaction with ENaC (epithelial sodium channel) and NF-kappaB signaling. In this study, we show that COMMD1 interacts with CFTR in cells expressing both proteins endogenously. This interaction promotes CFTR cell surface expression as assessed by biotinylation experiments in heterologously expressing cells through regulation of CFTR ubiquitination. In summary, our data demonstrate that CFTR is protected from ubiquitination by COMMD1, which sustains CFTR expression at the plasma membrane. Thus, increasing COMMD1 expression may provide an approach to simultaneously inhibit ENaC absorption and enhance CFTR trafficking, two major issues in cystic fibrosis

Copernicus Marine Service Ocean State Report

This is the final version. Available from Taylor & Francis via the DOI in this record

Integrated monitoring of mola mola behaviour in space and time

Over the last decade, ocean sunfish movements have been monitored worldwide using various satellite tracking methods. This study reports the near-real time monitoring of finescale (< 10 m) behaviour of sunfish. The study was conducted in southern Portugal in May 2014 and involved satellite tags and underwater and surface robotic vehicles to measure both the movements and the contextual environment of the fish. A total of four individuals were tracked using custom-made GPS satellite tags providing geolocation estimates of fine-scale resolution. These accurate positions further informed sunfish areas of restricted search (ARS), which were directly correlated to steep thermal frontal zones. Simultaneously, and for two different occasions, an Autonomous Underwater Vehicle (AUV) videorecorded the path of the tracked fish and detected buoyant particles in the water column. Importantly, the densities of these particles were also directly correlated to steep thermal gradients. Thus, both sunfish foraging behaviour (ARS) and possibly prey densities, were found to be influenced by analogous environmental conditions. In addition, the dynamic structure of the water transited by the tracked individuals was described by a Lagrangian modelling approach. The model informed the distribution of zooplankton in the region, both horizontally and in the water column, and the resultant simulated densities positively correlated with sunfish ARS behaviour estimator (r(s) = 0.184, p < 0.001). The model also revealed that tracked fish opportunistically displace with respect to subsurface current flow. Thus, we show how physical forcing and current structure provide a rationale for a predator's finescale behaviour observed over a two weeks in May 2014

Comparaison des performances des capteurs héliothermiques plans

Il est procédé à une comparaison systématique des performances des différents types de capteurs héliothermiques plans à l'aide des données météorologiques horaires disponibles à Trappes et à Carpentras. L'intégration des capteurs à un système de chauffage domestique ou à un système de production d'eau chaude sanitaire est étudiée. L'influence de plusieurs paramètres comme la température de fonctionnement, la surface de captation, l'orientation du capteur, l'inertie thermique et le volume de stockage est analysée. L'avantage des capteurs très performants (sélectif anti-convectifs) est clairement établi. Ainsi, une surface de captation de 50 m2 en région parisienne permet d'obtenir, pour un volume de 225 m3 ayant un coefficient de perte volumique de 1,5 W/m3 °C, des économies de chauffage de 45 % à une température de fonctionnement de 70°C

Phase-modulated ellipsometer using a Fourier transform infrared spectrometer for real time applications

A new Fourier transform infrared phase‐modulated ellipsometer is presented. It combines the high frequency provided by a photoelastic modulator (37 kHz) with the low frequency of the Fourier transform infrared spectroscopy (&lt;1 kHz), by means of a numerical data acquisition system. A full spectrum recording (from 900 to 4000 cm−1) can be achieved in 2 s. Thus, it allows its adaptation for kinetic in situ studies. The optical setup and the data reduction procedure are presented. In particular, a self‐consistent spectral calibration procedure is described in detail. The precision in Ψ and Δ increases from 0.3° to 0.02° when increasing the integration time from 2 to 760 s. The examples shown in this article illustrate the high sensitivity to identify and analyze the absorption vibration variations of ultrathin films (a few angstroms thick)

Comparaison des performances des capteurs héliothermiques plans

A systematic comparison of flat-plate collector efficiencies is performed, using hourly solar radiation measurements at Trappes and Carpentras. The integration to space heating or domestic hot water production systems is studied. The influence of some parameters as operation temperature, collection area, collector orientation, thermal inertia and thermal storage volume is considered. The interest of using collectors of high performance (selective-non-convective) is clearly established. A 50 m2 captation area of such collectors to heat a building of 225 m3 in volume and a volumic loss coefficient of 1.5 W/m3 °C, enables 45 % savings in the region of Paris at an operation temperature of 70 °C.Il est procédé à une comparaison systématique des performances des différents types de capteurs héliothermiques plans à l'aide des données météorologiques horaires disponibles à Trappes et à Carpentras. L'intégration des capteurs à un système de chauffage domestique ou à un système de production d'eau chaude sanitaire est étudiée. L'influence de plusieurs paramètres comme la température de fonctionnement, la surface de captation, l'orientation du capteur, l'inertie thermique et le volume de stockage est analysée. L'avantage des capteurs très performants (sélectif anti-convectifs) est clairement établi. Ainsi, une surface de captation de 50 m2 en région parisienne permet d'obtenir, pour un volume de 225 m3 ayant un coefficient de perte volumique de 1,5 W/m3 °C, des économies de chauffage de 45 % à une température de fonctionnement de 70°C