The photospheric radius is one of the fundamental parameters governing the radiative equilibrium of a star. We report new observations of the nearest solar-type stars alpha Centauri A (G2V) and B ...(K1V) with the VLTI/PIONIER optical interferometer. The combination of four configurations of the VLTI enable us to measure simultaneously the limb darkened angular diameter theta sub(LD) and the limb darkening parameters of the two solar-type stars in the near-infrared H band (lambda= 1.65 mu m). We obtain photospheric angular diameters of theta sub(LD)(A) = 8.502 + or - 0.038mas (0.43%) and theta sub(LD)(B) = 5.999 + or - 0.025mas (0.42%), through the adjustment of a power law limb darkening model. We find H band power law exponents of alpha (A) = 0.1404 + or - 0.0050 (3.6%) and alpha (B) = 0.1545 + or - 0.0044 (2.8%), which closely bracket the observed solar value ( alpha sub(middot in circle)= 0.15027). Combined with the parallax pi= 747.17 + or - 0.61mas previously determined, we derive linear radii of R sub(A)= 1.2234 + or - 0.0053 R sub(middot in circle)(0.43%) and R sub(B)= 0.8632 + or - 0.0037 R sub(middot in circle)(0.43%). The power law exponents that we derive for the two stars indicate a significantly weaker limb darkening than predicted by both 1D and 3D stellar atmosphere models. As this discrepancy is also observed on the near-infrared limb darkening profile of the Sun, an improvement of the calibration of stellar atmosphere models is clearly needed. The reported PIONIER visibility measurements of alpha Cen A and B provide a robust basis to validate the future evolutions of these models.
We demonstrate experimentally a simultaneous threefold modal and wavelength conversion process of a 10-Gbit/s On/Off keying signal in a 1.8-km long graded-index 6-LP-mode fiber. The principle of ...operation is based on a phase-matched inter-modal four-wave mixing phenomenon occurring between the fundamental mode and 3 higher-order modes of the fiber. The converted signals show well-opened eye-diagrams and error-free processing.
Le dialogue est une activité conjointe au cours de laquelle au moins deux locuteurs interagissent afin d’atteindre un but commun. Tout au long de cette interaction, chaque locuteur met en œuvre un ...certain nombre de processus qui contribuent à la réussite du dialogue. L’objectif de cette revue est de présenter les approches théoriques qui ont été développées dans le but de rendre compte de ces processus. La première partie est consacrée à l’approche collaborative, qui considère que le dialogue est une activité au cours de laquelle chacun des locuteurs s’adapte à son partenaire. La deuxième partie est consacrée à l’approche égocentrique, qui précise que, dans certaines situations, les partenaires parviennent à se comprendre sans qu’ils ne se comportent de façon adaptative. Enfin, la dernière partie est consacrée à la présentation d’approches alternatives aux deux précédentes et à la façon dont ces alternatives permettent, dans une certaine mesure, de dépasser l’antagonisme entre collaboration et égocentrisme.
Dialogue is a joint activity during which at least two partners interact in order to reach a common goal. Throughout the interaction, each speaker resorts to a number of processes, which contribute to dialogue success. Several theoretical approaches have been developed in order to account for these processes. Among these approaches, the collaborative approach can be considered as the most influent one in the field. This approach offers a global framework for dialogue by pointing out that interactively building up mutual knowledge allows partners to adapt to each other during the remainder of the interaction. This implies that speakers frequently resort to costly inferential processes to determine what their partner is likely to know and what he or she is also likely to ignore. However, this approach has seriously been challenged by the egocentric approach, which suggests that speakers sometimes fail to take into account their partners’ dialogic needs. Furthermore, recent work within this approach has pointed out that adaptation is not systematically necessary for dialogue to succeed – rather, individual processes at play within each speaker incidentally contribute to mutual understanding. The probabilistic approach offers a means to overcome the apparent discrepancy between collaboration and egocentrism by showing how the processes at play during reference production and comprehension may be simultaneously affected by both kinds of influences. Moreover, the relative weighting of each kind of influence depends on the characteristics of the dialogue situation per se: speakers are more or less likely to act collaboratively depending on the situation they find themselves in. Finally, the interactive alignment model offers a qualitatively different framework for dialogue, as it suggests that most dialogic behaviors can be accounted for by one single automatic process. The aim of the current review is to provide a thorough presentation of each of these approaches, and to determine to what extent they are compatible with each other, on one hand and how they differ, on the other. We also raise the question of the apparent easiness of dialogue, looking at how – according to each approach – speakers deal with the individual and collective costs inherent in dialogue. We finally point out a number of issues that remain to be addressed in this research field.
We describe the total lipid content, lipid class composition and fatty acid profiles of adult forage fishes (anchovy, sardine and sprat) sampled in the NW Mediterranean Sea in 2010 and 2011. Inter- ...and intra-species differences were mostly related to sampling period with limited effect of gender or total length. As an assemblage, total lipid content and relative levels of triacylglycerols and fatty acids 16:1n7, 20:5n3 and 14:0 in forage fish were highest in summer and autumn, indicating better feeding conditions and a more pronounced diatom-supported food web. In contrast, total lipid content was lowest at the end of winter and spring, and coincided with high levels of 22:6n3, indicating a more herbivorous diet based on dinoflagellates. Resource partitioning and niche separation, as inferred from fatty acid profiles, were apparent between species. Sardine showed a more diverse, temporally separated feeding strategy than anchovy, and dietary overlap was higher in winter than summer with sardine having higher markers of copepods, 22:1n11 and 20:1n9. Sprat collected in winter occupied a separate niche area to both sardine and anchovy with higher total lipid content and carnivory biomarker 18:1n9. Our results show that the lipid dynamics of forage fishes can be used to gain quantitative insights into sub-system level changes in species interactions, including prey and predator productivity.
Context. The dipole modes are the most common geometry of oscillations in roAp stars inferred from photometric measurements and are therefore of special interest for asteroseismic purposes. Aims. We ...present a theoretical and analytical study of the light curves associated with dipole (ℓ = 1) pulsations of roAp stars in the framework of the revisited oblique pulsator model. Methods. We describe the light curves in terms of the inclination and polarization of the elliptical displacement vector of the dipole modes. We study the influence of the magnetic field and rotation on the shape of these light curves for both amplitudes and phases. Results. Despite the inclination of dipole mode with respect to the magnetic axis, we find that the dipole mode can have maxima that are in phase with the magnetic maxima. We apply our formalism to the well-known roAp star HR 3831 (HD 83368) to derive its mode properties. Our results are similar to those obtained by time-series spectroscopy. We also consider the cases of three other roAp stars, HD 6532, HD 99563, and HD 128898 (α Cir). Conclusions. We demonstrate that the formalism of the revisited oblique pulsator model is adequate to explain the properties of the photometric light curves associated with dipole modes in roAp stars. In addition, we show that the coincidence of pulsation and magnetic extrema can also occur for inclined modes with respect to the magnetic axis. With the stars considered in this paper, we conclude that the polarization of the modes present in roAp stars are quasi linearly polarized.
Introduction
Adapted physical activity (APA) has beneficial neurobiological impact but the underlying pathophysiological mechanisms remain poorly described. APA is currently recognized as an adjuvant ...therapy to antipsychotic treatments in patients with schizophrenia (SCZs) to reduce the severity of negative symptoms and cognitive impairment. SCZs exhibit hippocampal N-acetylaspartate (NAA) reduction, a marker of neuronal viability and integrity whose concentrations can be assessed by proton magnetic resonance spectroscopy (
1
H-MRS).
Objectives
The purpose of this study was to evaluate the impact of remote physical activity (e-APA) via the web on the NAA relative variations in the left hippocampus in SCZs compared to a patient control group benefiting from an health education program (HE). This study concerns one of the secondary objectives of the PEPsy V@SI study co-financed by the Pierre Deniker Foundation, the European Union and the Normandy Region within the framework of the FEDER/FSE 2014-2020 operational program.
Methods
Thirty-five SCZs were randomized in the e-APA active group or in the control group (HE). Participants received the interventions during 16 weeks, with two visioconference sessions per week. A
1
H-MRS sequence positioned on the left hippocampus (MRI-3T) was acquired before and after both interventions. Absolute NAA concentrations in the left hippocampus were obtained using Osprey software after partial volume correction. After checking the quality criteria, the spectra of 6 SCZs in the e-APA group and 8 SCZs in the HE group were analyzed. To test the difference between interventions on the NAA relative variations, a Wilcoxon-Mann-Whitney test and effect size were performed. Paired Wilcoxon tests were used in each group before and after the interventions.
Results
No significant difference was found in NAA relative variations in the left hippocampus between the e-APA group and the HE group (p = 0.18), although the effect size was 0.38 (considered as moderate). However, a trend towards an increase of NAA was observed in the e-APA group (before intervention: 12.08 International Units (I.U); after: 13.81 I.U) (p = 0.06) but not in the HE group (before intervention: 13.75 I.U ; after: 13.85 I.U) (p = 0.84).
Conclusions
Our results showed a NAA significant increase in SCZs after an e-APA program, indicating a beneficial impact of e-APA on neuronal viability that might reflect an hippocampal plasticity. However, this increase did not differ significantly between active and control groups probably due to a weak statistical power.
Disclosure of Interest
L. Metivier: None Declared, F. Briend: None Declared, M. Tréhout: None Declared, L. Bigot: None Declared, G. Quarck: None Declared, A. Herbinet: None Declared, E. Leroux: None Declared, S. Dollfus Consultant of: Fabre,Gedeon,Roche and Takeda, inivited Conferences by Lundbeck, Otsuka, Janssen ; at contracts with Prophase MedAvances and NeuroCogTrials
We investigate non-local thermodynamic equilibrium (NLTE) effects for magnesium and calcium in the atmospheres of late-type giant and supergiant stars. The aim of this paper is to provide a grid of ...NLTE/LTE equivalent width ratios W/W* of Mg and Ca lines for the following range of stellar parameters: T
eff∈ 3500, 5250 K, log g∈ 0.5, 2.0 dex and Fe/H ∈ − 4.0, 0.5 dex. We use realistic model atoms with the best physics available and taking into account the fine structure. The Mg and Ca lines of interest are in optical and near-IR ranges. A special interest concerns the lines in the Gaia spectrograph Radial Velocity Spectrometer (RVS) wavelength domain 8470, 8740 Å. The NLTE corrections are provided as a function of stellar parameters in an electronic table as well as in a polynomial form for the Gaia/RVS lines.
Identification of the potential habitat of European anchovy (Engraulis encrasicolus) at different life stages in relation to environmental conditions is an interesting subject from both ecological ...and management points of view. For this purpose, acoustic data from different seasons and different parts of the Mediterranean Sea along with satellite environmental and bathymetry data were modelled using generalized additive models. Similarly, egg distribution data from summer ichthyoplankton surveys were used to model potential spawning habitat. Selected models were used to produce maps presenting the probability of anchovy presence (adults, juveniles and eggs) in the entire Mediterranean basin, as a measure of habitat adequacy. Bottom depth and sea surface chlorophyll concentration were the variables found important in all models. Potential anchovy habitats were located over the continental shelf for all life stages examined. An expansion of the potential habitat from the peak spawning (early summer) to the late spawning season (early autumn) was observed. However, the most suitable areas for the presence of anchovy spawners seem to maintain the same size between seasons. Potential juvenile habitats were associated with highly productive inshore waters, being less extended and closer to coast during winter than late autumn. Potential spawning habitat in June and July based on ichthyoplankton surveys overlapped but were wider in extent compared with adult potential habitat from acoustics in the same season. Similarities and dissimilarities between the anchovy habitats as well as comparisons with sardine habitats in the oligotrophic Mediterranean Sea and other ecosystems with higher productivity are discussed.
The Gulf of Lions ecosystem was described using the Ecopath mass-balance model to characterise its structure and functioning and to examine the effects of the multispecific fisheries operating in ...this area. The model is composed of 40 compartments, including 1 group of seabirds, 2 groups of cetaceans, 18 groups of fish, 12 groups of invertebrates, 5 groups of primary producers, detritus and discards. Input data were based on several recurrent scientific surveys, two alternative datasets for fishing data, stock assessment outputs, stomach content analyses and published information. Results showed that the functional groups were organised into five trophic levels with the highest one represented by dolphins, anglerfish, Atlantic bluefin tuna, European hake and European conger. European pilchard and European anchovy dominated in terms of fish biomass and catch. Other fish with high biomass such as Atlantic mackerel and blue whiting were highly important in the food web. Seabirds, dolphins and cuttlefish–squids represented keystone species. Important coupled pelagic–demersal–benthic interactions were described. The 7 different fisheries analysed were operating at mean trophic levels situated between 2.6 for small artisanal boats, and 4.1 for purse seines (>24m) targeting large pelagic fish, indicating an intensively exploited ecosystem. Large trawlers (24–40m) had the highest impact on most of the groups considered; while purse seines (12–24m) targeting small pelagic fish had the lowest impact. Preliminary results highlighted the importance of data sources for further ecosystem and fisheries analyses and management scenarios.
► We characterize the structure and the functioning of the food web in the Gulf of Lion. ► European pilchard and European anchovy represented key link groups and high landings. ► We showed coupling between compartments and top-down control by demersal predators. ► Indices showed that the Gulf of Lion's ecosystem was highly exploited by fisheries. ► Large trawls had the most negative impact and small purse seines had the lowest one.
We propose a numerical methodology for detecting periodicities in unknown colored noise and for evaluating the 'significance levels' (p-values) of the test statistics. The procedure assumes and ...leverages the existence of a set of time series obtained under the null hypothesis (a null training sample, NTS) and possibly complementary side information. The test statistic is computed from a standardized periodogram, which is a pointwise division of the periodogram of the series under test to an averaged periodogram obtained from the NTS. The procedure provides accurate p-values estimation through a dedicated Monte Carlo procedure. While the methodology is general, our application is here exoplanet detection. The proposed methods are benchmarked on astrophysical data.
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