A comprehensive study of the SX Phoenicis star BL Camelopardalis

Astronomy and Astrophysics, v. 451, p. 999-1008, 2006. http://dx.doi.org/10.1051/0004-6361:20053841International audienc

First joint observations of space weather events over Mexico

Abstract. The Mexican Space Weather Service (SCiESMEX in Spanish) and National Space Weather Laboratory (LANCE in Spanish) were organized in 2014 and in 2016, respectively, to provide space weather monitoring and alerts, as well as scientific research in Mexico. In this work, we presenttheresultsofthefirstjointobservationsoftwoevents (22 June and 29 September 2015) with our local network of instruments and their related products. This network includes the MEXART radio telescope (solar flare and radio burst), the Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories (CALLISTO)attheMEXARTstation(solarradioburst),the Mexico City Cosmic Ray Observatory (cosmic ray fluxes), GPS receiver networks (ionospheric disturbances), and the Teoloyucan Geomagnetic Observatory (geomagnetic field). The observations show that we detected significant space weather effects over the Mexican territory: geomagnetic and ionospheric disturbances (22 June 2015), variations in cosmicrayfluxes,andalsoradiocommunications’interferences (29September2015).Theeffectsoftheseperturbationswere registered,forthefirsttime,usingspaceweatherproductsby SCiESMEX:totalelectroncontent(TEC)maps,regionalgeomagneticindexKmex,radiospectrographsoflowfrequency, and cosmic ray fluxes. These results prove the importance of monitoring space weather phenomena in the region and the need to strengthening the instrumentation network

Trypanosoma cruzi calmodulin: Cloning, expression and characterization

1 - ArticleWe have cloned and expressed calmodulin (CaM) from Trypanosoma cruzi, for the first time, to obtain large amounts of protein. CaM is a very well conserved protein throughout evolution, sharing 100% amino acid sequence identity between different vertebrates and 99% between trypanosomatids. However, there is 89% amino acid sequence identity between T. cruzi and vertebrate CaMs. The results demonstrate significant differences between calmodulin from T. cruzi and mammals. First, a polyclonal antibody developed in an egg-yolk system to the T. cruzi CaM recognizes the autologous CaM but not the CaM from rat. Second, it undergoes a larger increase in the alpha-helix content upon binding with Ca(2+), when compared to CaM from vertebrates. Finally, two classic CaM antagonists, calmidazolium and trifluoperazine, capable of inhibiting the action of CaM in mammals when assayed on the plasma membrane Ca(2+) pump, showed a significant loss of activity when assayed upon stimulation with the T. cruzi CaM

Asteroseismology of the Beta Cephei star 12 (DD) Lacertae : photometric observations, pulsational frequency analysis and mode identification

Monthly Notices of the Royal Astronomical Society, v. 365, n. 1, p. 327-338, 2006. http://fr.arxiv.org/abs/astro-ph/0510326v1International audienc

Characterization of micronektonic spatial structure using ecosystemic acoustics descriptors applied in three Atlantic African Large Marine Ecosystems

ICAWA : International Conference AWA, Lanzarote, ESP, 17-/04/2018 - 20/04/2018Using the segmentation algorithm within Matecho (Perrot et al., 2018) we are able to deliver 15 descriptors to characterize the acoustic micronektonic layers in the water column. Even if the species composition is not known, these descriptors which are obtained using the same methodology allow for comparison between ecosystems and to study inter-annual variability. Some of these descriptors are new and others are based on the ones usually used to characterize pelagic fish schools using echointegration per shoal (Weill et al., 1993). In this work we will focus on the new ones and show some application cases in the three Atlantic African Large Marine Ecosystems, to monitor potential perturbations due to global change. All layer descriptors are estimated per layer and per elementary sampling unit of 0.1 nautical miles (ESU) with an accuracy of 1 meter depth. In this study we present four classes of descriptors: spatial (e.g. altitude, mean depth, minimal depth); morphological (e.g. width, ESU number, filling rate of water column); acoustic (e.g. mean volume backscattering strength Sv (dB)) and the layer number per ESU. In this study we focus on the original descriptors: (i) Filling rate of the water column (%): this indicator is based on the calculation of the width of the micronektonic layer vs. the local bottom depth. (ii) Filling rate contribution of first layer (%): this indicator shows the contribution of the first layer (the closest layer of surface) in the global filling rate. It is computed by dividing the filling rate of first layer by the filling rate of all layers. (iii) Number of layers: this indicator is calculated for each ESU, giving the number of layers in this water column. The descriptors have been computed over more than 1 million of ESUs, 992 737 in the CCLME, 166 183 in the GCLME and 462 807 in the BCLME. Such descriptors allow classification of micronekton layers and appear relevant to monitor changes in the ecosystem. Next step will be to use multifrequency or even wide-band data to improve the quality of descriptors. They were efficiently applied to study diel vertical behaviour as well as the effect of water mass characteristics on the spatial structure of the layers. In future applications it should help in the classification of the layers per functional group as well as to improve our knowledge on ecosystem organization and functioning

Comparative analysis of Diel Vertical migration between three Atlantic African large marine ecosystems

ICAWA : International Conference AWA, Lanzarote, ESP, 17-/04/2018 - 20/04/2018Diel vertical migration (DVM) of micronekton is a behavioural mechanism driven by a trade-off between predator avoidance and access to prey. This trade-off is controlled by environmental forcing that can lead to changes of DVM pattern under changing environmental conditions. Time series of hydro acoustic surveys between 1995 – 2015 of three large Atlantic ecosystems (Canary Current - CCLME, Guinea Current - GCLME, and Benguela Current - BCLME) were analysed to calculate DVM patterns based on volume backscattering strength (Sv). DVM related descriptors (n=15) were calculated for areas according to bathymetric definitions (shelf = 10 – 150 m bottom depth, slope = 150 – 500 m bottom depth, and plain > 500 m bottom depth). Typical DVM I pattern, with micronekton descending during daytime and ascending during night-time, were observed on the slope and plain in all three ecosystems, but not on the shelf with only negative day-night values in the CCLME and BCLME. Lower daytime Sv values during the day compared to night-time suggest either less dense patches of micronekton leading to negative day-night differences in the CCLME and GCLME or insufficient measurements of certain depth strata (e.g., 0 – 10 m surface). Only a few significant and different DVM descriptors suggest a change in the CCLME and the GCLME in the last 20 years. All other insignificant descriptors assume natural variability in large Atlantic ecosystems. Our results provide insight into inter-annual variability in micronekton DVM patterns

Seasonal variations of O₂ atmospheric and OH(6?2) airglowand temperature at mid-latitudes from SATI observations

International audienceMore than 3 years of airglow observations with a Spectral Airglow Temperature Imager (SATI) installed at the Sierra Nevada Observatory (37.06°N, 3.38°W) at 2900m height have been analyzed. Values of the column emission rate and vertically averaged temperature of the O2 atmospheric (0?1) band and of the OH Meinel (6?2) band from 1998 to 2002 have been presented. From these observations a clear seasonal variation of both emission rates and rotational temperatures is inferred at this latitude. It is found that the annual variation of the temperatures is larger than the semi-annual variation, while for the emission rates the amplitudes are comparable. Key words. Atmospheric composition and structure (airglow and aurora; pressure density and temperature; instruments and techniques

Unsupervised functional classification applied on high resolution oceanographic data in Canaries Current Large Marine Ecosystem : toward fine scale analysis

ICAWA : International Conference AWA, Lanzarote, ESP, 17-/04/2018 - 20/04/2018The understand of the fine scale process occurring in the ocean needs high resolution data and ad hoc analysis approach to improve the knowledge of ecosystem functioning. During an international survey carry out in 2014'AWA’ on-board the research vessel Thalassa (Ifremer, Brest) along the coast of Mauritania and Senegal we have used simultaneously multifrequency scientific echosounder and a Scanfish, both system allow a continuous acquisition of high- quality data at high spatial and temporal resolution over long distance. The functional data analyses have recently raising in serval field of statistics and appear to be well suited for the analysis of this dataset. In fact such data has spatial-functional nature and may be considered as observations of a stochastic process X in space of continuous functions over an interval T. Let X1(t), X2(t),.., Xn(t), t T, be the collection of n observations from X. First, we study an eventual horizontally or vertically variation of the acoustic intensity, we consider for a given frequency (here 200 kHz) and one vessel radial the two cases: vertical and horizontal variations of the acoustic intensity. Unsupervised functional classification used, shows a horizontal and vertical variation of acoustic intensity for a given frequency and a given radial. The approach can led to scrutinized at fine scale the processes occurring in three dimensions in the pelagic environment. The statistical functional classification applied to this case study appears powerful, ad hoc for ecological studies of marine ecosystem and will be extend to model the spatial structuration of the pelagic ecosystem according to the physcio-chemical parameters of the water mass which will allow to improve the forecast of the effect of the environment on marine ecosystem organization

Unsupervised functional classification applied on high resolution oceanographic data in Canaries Current Large Marine Ecosystem : toward fine scale analysis

ICAWA : International Conference AWA, Lanzarote, ESP, 17-/04/2018 - 20/04/2018The understand of the fine scale process occurring in the ocean needs high resolution data and ad hoc analysis approach to improve the knowledge of ecosystem functioning. During an international survey carry out in 2014'AWA’ on-board the research vessel Thalassa (Ifremer, Brest) along the coast of Mauritania and Senegal we have used simultaneously multifrequency scientific echosounder and a Scanfish, both system allow a continuous acquisition of high- quality data at high spatial and temporal resolution over long distance. The functional data analyses have recently raising in serval field of statistics and appear to be well suited for the analysis of this dataset. In fact such data has spatial-functional nature and may be considered as observations of a stochastic process X in space of continuous functions over an interval T. Let X1(t), X2(t),.., Xn(t), t T, be the collection of n observations from X. First, we study an eventual horizontally or vertically variation of the acoustic intensity, we consider for a given frequency (here 200 kHz) and one vessel radial the two cases: vertical and horizontal variations of the acoustic intensity. Unsupervised functional classification used, shows a horizontal and vertical variation of acoustic intensity for a given frequency and a given radial. The approach can led to scrutinized at fine scale the processes occurring in three dimensions in the pelagic environment. The statistical functional classification applied to this case study appears powerful, ad hoc for ecological studies of marine ecosystem and will be extend to model the spatial structuration of the pelagic ecosystem according to the physcio-chemical parameters of the water mass which will allow to improve the forecast of the effect of the environment on marine ecosystem organization