Abstract: The HAMSTRAD (H2O Antarctica Microwave Stratospheric and Tropospheric Radiometers) instrument is a microwave radiometer installed at Dome C (Antarctica, 75°06'S, 123°21'E, 3233 m amsl) dedicated to the tropospheric measurements of temperature, absolute humidity and integrated water vapour (IWV). The aim of the present paper is to review the entire HAMSTRAD data set from 2009 to 2014 with a 7-minute integration time from 0 to 10 km by comparison with coincident radiosondes launched at 12:00 UTC at Dome C. Based upon an extensive evaluation of biases and time correlation coefficients (r), we can state: 1) IWV is of excellent quality (r > 0.98) and can be used without retrieving significant bias, 2) temperature is suitable for scientific analyses over the range 0-10 km with a high time correlation with radiosondes (r > 0.80) and 3) absolute humidity is suitable for scientific analyses in the range 0-4 km with a moderate time correlation against radiosondes (r > 0.70). The vertical distribution of temperature (0-10 km) and absolute humidity (0-4 km) is subject to biases that need to be removed if the analyses require the use of vertical profiling. The HAMSTRAD data set is given in open access to the scientific community.

Abstract: Sex allocation theory predicts that parents should bias offspring sex according to the costs and benefits associated with producing either sex in a given context. Accurately interpreting sex-ratio biases, therefore, requires a precise identification of these selective pressures. However, such information is generally lacking. This may partly explain the inconsistency in reported sex allocation patterns, especially in vertebrates. We present data from a long-term feeding experiment in black-legged kittiwakes (Rissa tridactyla) that allowed us to increase investment capacity for some breeding pairs. Previous findings showed that these pairs then overproduced sons compared with control parents. Here, our aim was to test the underlying assumptions of the 2 appropriate sex allocation models for our context: the “cost of reproduction hypothesis” and the “Trivers-Willard hypothesis.” The former assumes a sex difference in rearing costs, whereas the latter assumes a difference in fitness returns. 1) Independent of feeding treatment, rearing sons was energetically more demanding for parents (as revealed by higher energy expenditure and higher baseline corticosterone levels) than rearing daughters, thereby corroborating the underlying assumption of the “cost of reproduction hypothesis.” 2) Evidence supporting the assumptions of the “Trivers-Willard hypothesis” was less convincing. Overall, our results suggest that drivers of parental sex allocation decisions are probably more related to offspring sex-specific energetic costs than to their future reproductive success in our study species. Assessing the adaptive value of sex-ratio biases requires precise investigation of the assumptions underlying theoretical models, particularly as long as the mechanisms involved in sex-ratio manipulation remain largely unknown.

Abstract: In this work, we model the polarisation of the auroral red line using the electron impact theory developed by Bommier et al (2011). This theory enables the computation of the distribution of the Degree of Linear Polarisation (DoLP) as function of height if the flux of precipitated electrons is provided as input.\\
An electron transport code is used to infer the stationary electron flux at each altitude in the ionosphere as a function of energy and pitch angle. Using adequate cross sections, the integral of this electron flux over energy and pitch angle provides an anisotropy parameter from which the theoretical local DoLP can be computed at each altitude. The modelled DoLP is then derived by integrating along the line-of-sight.\\
Depending on the integration length, the modelled DoLP ranges between 0.6\% for a very long integration length, and 1.8\% for a very short integration length localized around an altitude of 210 km. A parametric study is performed to check how the characteristics of the local DoLP (maximum value, altitude of the maximum, integrated height profile) vary. It is found that the polarisation is highly sensitive to the scattering function of the electrons, to the electron precipitation and the geomagnetic activity.\\
We compare these values to measured ones obtained during an observational campaign performed in February 2012 from Svalbard. The measured DoLP during the campaign was 1.9\% $\pm$ 0.1\%. The comparison between this value and the theoretical one is discussed . Discrepancies may be due to the poor constraint of the input parameters (thermosphere and ionosphere), to the fact that only electron precipitation is considered in this approach (and not proton precipitation for instance), and to the difficulty in constraining the exact width of the emission layer in the thermosphere.

Abstract: Capture-recapture software packages have proven to be very powerful tools for analyzing factors affecting survival in wild populations. However all such packages are limited to discrete-time protocols. Appropriate survival analysis tools are still lacking for data acquired from continuous-time protocols.
We have developed a statistical method and propose an R package for analyzing such data based on an extension of classical survival analysis models incorporating an inhomogeneous Poisson process for modeling capture histories. First, data were simulated from a continuous-time protocol. These data were used to i) compare survival estimation biases of discrete- and continuous-time approaches and ii) investigate the performance and accuracy of our R package for four types of covariates: factors varying between individuals (like sex), in time (like climatic factors), both in time and between individuals (like physical condition) and age (as a categorical factor). Second, the R package has been applied to a real data set for survival analysis of cats in the Kerguelen archipelago (regrouping 682 cats over 20 years) as an illustrative example.
Results of the simulated data analysis show that the method performs better than its discrete-time counterpart for analyzing data acquired from continuous-time protocols. It provides unbiased parameter estimates for all parameters except those that vary both in time and between individuals – which is not surprising, since in our case these factors were not updated in continuous-time (i.e., only upon capture). When applied to the Kerguelen cat data set, the results suggest that survival is lower in juveniles than in adults and sub-adults, varies between study sites, and increases with physical condition, this latter effect being more important in females than in males. Sex, season, temporal linear trend in survival, and the NDVI vegetation index, were also tested but were not found to be significant. However, confidence intervals were too large (due to a low recapture rate) for excluding such effects. Further analyses are still needed for rigorous covariate testing in this context.
In conclusion, continuous-time approaches – such as that presented in this paper – should be preferred when data acquired from continuous-time protocols is analyzed.