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This paper discusses results from the second phase of the European Ice Sheet Modelling Initiative (EISMINT). It reports the intercomparison of ten operational ice-sheet models and uses a series of experiments to examine the implications of thermomechanical coupling for model behaviour. A schematic, circular ice sheet is used in the work which investigates both steady states and the response to stepped changes in climate. The major finding is that the radial symmetry implied in the experimental design can, under certain circumstances, break down with the formation of distinct, regularly spaced spokes of cold ice which extended from the interior of the ice sheet outward to the surrounding zone of basal melt. These features also manifest themselves in the thickness and velocity distributions predicted by the models. They appear to be a common feature to all of the models which took part in the intercomparison, and may stem from interactions between ice temperature, flow and surface form. The exact nature of these features varies between models, and their existence appears to be controlled by the overall thermal regime of the ice sheet. A second result is that there is considerable agreement between the models in their predictions of global-scale response to imposed climate change.
The concept of cognitive reserve (CR) hypothesizes that intellectually stimulating activities provide resilience against brain pathology/disease. Whereas brain abnormalities and cognitive impairment are frequently reported in bipolar disorder (BD), it is unknown whether the impact of brain alterations can be lessened by higher CR in BD.
We tested if higher CR would reduce the influence of total volumes of deep white matter hypointensities (WMH), ventricular cerebrospinal fluid (CSF), and prefrontal cortex on memory, executive, and attention/speed functions in patients with BD (n = 75). Linear regression models with interaction terms for CR and brain volumes were applied to directly test if CR reduces the influence of brain pathology on cognitive domains.
CR reduced the influence of total volumes of deep WMH (β = −0.38, Q = 0.003) and ventricular CSF (β = −41, Q = 006) on executive functions.
The interactions between CR and total volumes of deep WMH/ventricular CSF appear to account for executive functioning in BD. The results suggest that the concept of CR is applicable in BD. Higher reserve capacity in BD alters the relationship between brain pathology and clinical presentation.
We have made a 12CO(J = 1−0) survey of the LMC with NANTEN. A sample of 55 giant molecular clouds has been identified and comparisons with stellar clusters, HII regions and SNRs are presented. The connection between the clouds and cluster formation is discussed.
Fully sampled 12CO(J=1−0) observations of the whole extent of the LMC have been made with a linear resolution of ~ 30 pc at a detection limit of N(H2) = 2 × 1021 cm−2. In addition, several selected regions have been mapped with higher sensitivity corresponding to a detection limit of 1 × 1021 cm−2. Based on these results, a new estimate of the molecular mass in the LMC is presented.
We have made 12CO(J=1−0) observations of the LMC with NANTEN. We report the results of a comparison between CO clouds and SNRs in the LMC. Among the 35 known SNRs, only 10 are possibly associated with CO clouds. These 10 CO clouds and SNRs deserve follow-up studies for possible interactions. We present overlays of CO clouds on the optical images of some of these SNRs.
We have made 12CO(J=1-0) observations in the LMC with NANTEN, and compared the detected giant molecular clouds (GMCs) with HII regions and stellar clusters. It is found that ~ 80% of the GMCs are associated with HII regions. The results of comparisons of the GMCs with the HII regions and the stellar clusters are presented.
We have made 12CO(J=1−0) observations of the LMC with the NANTEN millimeter-wave telescope and identified about 100 distinct giant molecular clouds (GMCs). A detailed comparison of the GMCs with stellar clusters and a UV image is discussed.
A review of the MOA (Microlensing Observations in Astrophysics) project is presented. MOA is a collaboration of approximately 30 astronomers from New Zealand and Japan established with the aim of finding and detecting microlensing events towards the Magellanic Clouds and the Galactic bulge, which may be indicative of either dark matter or of planetary companions. The observing program commenced in 1995, using very wide band blue and red filters and a nine-chip mosaic CCD camera.
As a by-product of these observations a large database of CCD photometry for 1.4 million stars towards both LMC and SMC has been established. In one preliminary analysis 576 bright variable stars were confirmed, nearly half of them being Cepheids. Another analysis has identified large numbers of blue variables, and 205 eclipsing binaries are included in this sample. In addition 351 red variables (AGB stars) have been found. Light curves have been obtained for all these stars. The observations are carried out on a 61-cm f/6.25 telescope at Mt John University Observatory where a new larger CCD camera was installed in 1998 July. From this latitude (44° S) the Magellanic Clouds can be monitored throughout the year.
The red variables whose amplitude is larger than 1.3 mag in the MOA database are studied for the LMC. Among 3 196 such stars, 532 stars are likely to be Miras or red semiregular variables. The period–colour relation of these stars is shown.
A large database of CCD photometry for 1.4 million stars towards both the LMC and the SMC, which has been established by the MOA project, is a useful resource to study variable stars. In our preliminary study, variables identified as β Lyrae type stars and Herbig Ae/Be stars have been found amongst blue stars.
In traditional transit timing variations (TTVs) analysis of multi-planetary systems, the individual TTVs are first derived from transit fitting and later modelled using n-body dynamic simulations to constrain planetary masses. We show that fitting simultaneously the transit light curves with the system dynamics (photo-dynamical model) increases the precision of the TTV measurements and helps constrain the system architecture. We exemplify the advantages of applying this photo-dynamical model to a multi-planetary system found in K2 data very close to 3:2 mean motion resonance, K2-19. In this case the period of the larger TTV variations (libration period) is much longer (>1.5 years) than the duration of the K2 observations (80 days). However, our method allows to detect the short period TTVs produced by the orbital conjunctions between the planets that in turn permits to uniquely characterise the system. Therefore, our method can be used to constrain the masses of near-resonant systems even when the full libration curve is not observed.
Studies of the relationship between obesity and chronic kidney disease (CKD) in nationally representative population samples are limited. Our study aimed to determine if overweight and obesity were independently associated with the risk for CKD in the 2010 Health Survey for England (HSE).
The HSE is an annually conducted cross-sectional study. In 2010 serum creatinine was included to determine the incidence of CKD in the population. CKD was defined as estimated glomerular filtration rate (eGFR) <60 ml/min per 1·73 m2 using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula. Multivariable logistic regression models were developed to calculate odds ratios and 95 % confidence intervals for CKD risk by BMI (reference category: BMI=18·5–24·9 kg/m2) and adjusted for age, gender, ethnicity, smoking, diabetes and hypertension.
A random sample of nationally representative households in England.
Adults (n 3463) with calculable eGFR and BMI were included.
The prevalence of CKD was 5·9 %. The risk of CKD was over 2·5 times higher in obese participants compared with normal-weight participants in the fully adjusted model (BMI=30·0–39·9 kg/m2: adjusted OR=2·78 (95 % CI 1·75, 4·43); BMI ≥ 40·0 kg/m2: adjusted OR=2·68 (95 % CI 1·05, 6·85)).
Obesity is associated with an increased risk of CKD in a national sample of the UK population, even after adjustment for known CKD risk factors, which may have implications for CKD screening and future national health service planning and delivery.
We have prepared 2% Al doped ZnO (AZO) thin films on SrTiO3 and Al2O3 substrates by Pulsed Laser Deposition (PLD) technique at various deposition temperatures (Tdep = 300 °C – 600 °C). Transport and thermoelectric properties of AZO thin films were studied in low temperature range (300 K - 600 K). AZO/STO films present superior performance respect to AZO/Al2O3 films deposited at the same temperature, except for films deposited at 400 °C. Best film is the fully c-axis oriented AZO/STO deposited at 300 °C, with electrical conductivity 310 S/cm, Seebeck coefficient -65 μV/K and power factor 0.13 × 10-3 Wm-1K-2 at 300 K. Its performance increases with temperature. For instance, power factor is enhanced up to × 10-3 Wm-1K-2 at 600 K, surpassing the best AZO film previously reported in literature.
We present long term site testing statistics based on DIMM and GSM data obtained at Dome C, Antarctica. These data have been collected on the bright star Canopus since the end of 2003. We give values of the integrated turbulence parameters in the visible (wavelength 500 nm). The median value we obtained for the seeing are 1.2 arcsec, 2.0 arcsec and 0.8 arcsec at respective elevations of 8m, 3m and 20m above the ground. The isoplanatic angle median value is 4.0 arcsec and the median outer scale is 7.5m. We found that both the seeing and the isoplanatic angle exhibit a strong dependence with the season (the seeing is larger in winter while the isoplanatic angle is smaller).
The ASTEP project aims at detecting and characterizing transiting planets from Dome C, Antarctica, and qualifying this site for photometry in the visible. The first phase of the project, ASTEP South, is a fixed 10 cm diameter instrument pointing continuously towards the celestial South Pole. Observations were made almost continuously during 4 winters, from 2008 to 2011. The point-to-point RMS of 1-day photometric lightcurves can be explained by a combination of expected statistical noises, dominated by the photon noise up to magnitude 14. This RMS is large, from 2.5 mmag at R = 8 to 6% at R = 14, because of the small size of ASTEP South and the short exposure time (30 s). Statistical noises should be considerably reduced using the large amount of collected data. A 9.9-day period eclipsing binary is detected, with a magnitude R = 9.85. The 2-season lightcurve folded in phase and binned into 1,000 points has a RMS of 1.09 mmag, for an expected photon noise of 0.29 mmag. The use of the 4 seasons of data with a better detrending algorithm should yield a sub-millimagnitude precision for this folded lightcurve. Radial velocity follow-up observations reveal a F-M binary system. The detection of this 9.9-day period system with a small instrument such as ASTEP South and the precision of the folded lightcurve show the quality of Dome C for continuous photometric observations, and its potential for the detection of planets with orbital periods longer than those usually detected from the ground.
ASTEP (Antarctic Search for Transiting Exo Planets) is a research program funded mainly by French ANR grants and by the French Polar Institute (IPEV), dedicated to the photometric study of exoplanetary transits from Antarctica.
The preliminary “pathfinder” instrument ASTEP–South is described in another communication (Crouzet et al., these proceedings), and we focus in this presentation on the main instrument of the ASTEP program: “ASTEP–400”, a 40 cm robotized and thermally-controlled photometric telescope operated from the French-Italian Concordia station (Dome C, Antarctica).
ASTEP–400 has been installed at Concordia during the 2009-2010 summer campaign. Since, the telescope has been operated in nominal conditions during 2010 and 2011 winters, and the 2012 winterover is presently in progress. Data from the first two winter campaigns are available and processed. We give a description of the ASTEP–400 telescope from the mechanical, optical and thermal point of view. Control and software issues are also addressed. We end with a discussion of some astronomical results obtained with ASTEP–400.
The Dome C high plateau is unique for coronagraphic observations: sky brightness is reduced, water vapour is low, seeing is excellent and continuity of observations on several weeks is possible. ESCAPE (the Extreme Solar Coronagraphy Antarctic Program Experiment) will perform 2-dimensional spectroscopy of the forbidden line of FeXIV at 530.285 nm: precise line profile analysis will allow the diagnostic of the nature of waves by simultaneous measurements of velocities and intensities in the corona. ESCAPE is proposed to Institut Paul-Emile Victor (IPEV) for a campaign in 2012–2013 at Dome C/Concordia since all subsystems are available in particular thanks to an ESA STARTIGER 2010 R&D “Toward a New Generation of Formation Flying Coronagraph”. Using state-of-the-art technologies developed for Space missions (a Three Mirrors Anastigmat telescope, the TMA, a 4 stages Liquid Crystal Tunable-filter Polarimeter, the LCTP) allows us to propose an automated Coronal Green Line full-field Polarimeter for unique observations (waves nature and intensity to address coronal heating) with the best possible performances on Earth and for preparing and testing the technologies for the next steps in Space. No other site would allow such coronagraphic performances (the sky brightness is a factor 2 to 4 better than in Hawaï) and with high spatial resolution (better than an arcsec is possible).
Copper-based ohmic contacts to n-type 6H-SiC have been investigated. In this study, ohmic contacts have been fabricated with pulsed excimer laser irradiation to Cu-deposited substrates at room temperature. It is shown that current-voltage characteristics depend on the laser energy density. Contacts formed by the laser irradiation at the energy density above 1.2 J/cm2 have shown the ohmic behavior. Cu atoms have slightly diffused into SiC by the laser irradiation at 1.4 J/cm2. As a result, a thin ohmic contact layer has been obtained by the laser processing. AES and XRD study have revealed that a Cu-SiC alloy containing Cu silicide (Cu3Si) is formed by the laser irradiation.
Single crystals of Ba8CoRh6O21 were grown out of a potassium carbonate flux. The structure was solved by a general method using the superspace group approach. The superspace group employed was R3m(00γ)0s with a = 10.0431(1) Å, c1 = 2.5946(1) Å and c2 = 4.5405(1) Å, V = 226.60(1) Å3. Ba8CoRh6O21 represents the first example of an m = 5, n = 3 member of the A3n+3mA'nB3m+nO9m+6n family of 2H hexagonal perovskite related oxides and contains chains consisting of six consecutive RhO6 octahedra followed by one distorted CoO6 trigonal prism. These chains in turn are separated from each other by [Ba]∞ chains.