407 research outputs found
Long-term pulse profile study of the Be/X-ray pulsar SAX J2103.5+4545
Aims. We present the first long-term pulse profile study of the X-ray pulsar
SAX J2103.5+4545. Our main goal is to study the pulse shape correlation either
with luminosity, time or energy.
Methods. This Be/X-ray binary system was observed from 1999 to 2004 by RXTE
PCA, and by INTEGRAL from 2002 to 2005, during the Performance and Verification
(PV) phase and the Galactic Plane Scan survey (GPS). X-ray pulse profiles were
obtained in different energy ranges. The long-term spectral variability of this
source is studied. The long-term flux, frequency and spin-up rate histories are
computed. A new set of orbital parameters are also determined.
Results. The pulse shape is complex and highly variable either with time or
luminosity. However, an energy dependence pattern was found. Single, double,
triple or even quadruple peaks pulse profile structure was obtained. It was
confirmed that SAX J2103.5+4545 becomes harder when the flux is higher. The new
orbital solution obtained is: P_orb= 12.66528+-0.00051 days, e = 0.401+-0.018,
w = 241.36+-2.18 and a_xsin i = 80.81+-0.67 lt-s.Comment: 9 pages, 11 figures, submitted to Astronomy & Astrophysic
Effects of the presence of skins during alcoholic fermentation on the composition of wine volatiles
Der Einfluß des Beerenhautkontaktes während der alkoholischen Gärung auf die Zusammensetzung der WeinaromakomponentenDie Zusammensetzung der flüchtigen und nichtflüchtigen Inhaltsstoffe von Weinen, die aus einem Most der Rebsorte Cencibel unter vier verschiedenen Gärungsbedingungen gewonnen wurden, wird beschrieben. Die Vergärung durch Saccharomyces cerevisiae erfolgte mit oder ohne Beerenhäute und mit oder ohne SO2. Die mittels konventioneller Analysenmethoden und auf gaschromatographischem Wege gewonnenen Daten wurden der Faktoren- und Clusteranalyse unterzogen. Bei einigen Komponenten traten signifikante Konzentrationsunterschiede in Abhängigkeit von den Gärungsbedingungen auf
First observations of the X-ray transient EXO 2030+375 with IBIS/ISGRI
We present a first INTEGRAL observation of the 42s transient X-ray pulsar EXO
2030+375 with IBIS/ISGRI. The source was detected during Cyg X-1 observations
in December 2002. We analyzed observations during the outburst period from 9 to
21 December 2002 with a total exposure time of ~770 kiloseconds. EXO 2030+375
was almost always detected during single ~30 minute exposures in the 18-45
energy bands. The source light curve shows the characteristic outburst shape
observed in this source.Comment: 4 pages, 3 figures (1 in CMYK color), accepted by Astronomy and
Astrophysics, INTEGRAL special issue, 200
Unveiling the Relationship Between Sea Surface Hydrographic Patterns and Tuna Larval Distribution in the Central Mediterranean Sea
Thunnus thynnus (Atlantic bluefin tuna, ABT) and other tuna species reproduce in the Mediterranean Sea during the summer period. Despite the Central Mediterranean Sea, the Strait of Sicily in particular, being a key spawning site for many tuna species, little is known on the effects of oceanographic variability on their larval distribution in this area. The abundance and presence-absence of larval specimens for three tuna species (ABT, bullet tuna and albacore) were modeled in order to examine their relationships with environmental factors, by analysing historical in situ information collected during seven annual surveys (2010–2016). The results revealed that most tuna larvae for the three species were found in the easternmost part of the study area, south of Capo Passero. This area is characterized by a stable saline front and warmer nutrient-poor water, and it has different environmental conditions, compared with the surrounding areas. The models used to investigate the presence-absence and abundance of the three species showed that ABT was the most abundant, followed by bullet tuna and albacore. The presence and abundance data collected are comparable with those of other spawning areas in the Mediterranean. Regarding biological and physical parameters, the results suggest that temperature, salinity, and day of the year are the key factors for understanding the ecological mechanisms and geographical distribution of these species in this area. Temperature affects the presence of ABT larvae and salinity, which, with a physical barrier effect, is a key factor for the presence-absence of bullet and albacore and for albacore abundance
Dynamic prokaryotic communities in the dark western Mediterranean Sea
Dark ocean microbial dynamics are fundamental to understand ecosystem metabolism and ocean biogeochemical processes. Yet, the ecological response of deep ocean communities to environmental perturbations remains largely unknown. Temporal and spatial dynamics of the meso- and bathypelagic prokaryotic communities were assessed throughout a 2-year seasonal sampling across the western Mediterranean Sea. A common pattern of prokaryotic communities’ depth stratification was observed across the different regions and throughout the seasons. However, sporadic and drastic alterations of the community composition and diversity occurred either at specific water masses or throughout the aphotic zone and at a basin scale. Environmental changes resulted in a major increase in the abundance of rare or low abundant phylotypes and a profound change of the community composition. Our study evidences the temporal dynamism of dark ocean prokaryotic communities, exhibiting long periods of stability but also drastic changes, with implications in community metabolism and carbon fluxes. Taken together, the results highlight the importance of monitoring the temporal patterns of dark ocean prokaryotic communities.Versión del editor2,92
Bluefin tuna larval indices in the western Mediterranean, ecological and analytycal sources of uncertainity
The main objective of this study is to provide the knowledge to design adequate sensitivity
analyses on the assessment models used for the Eastern stock of Bluefin tuna. We analyze how
different configuration for the same environmental variable (temperature in the mixed layer
depth) and different modeling approaches (nonlinear Delta-log,delta-gamma, tweedy and
bayesian) affects to the variability of the larval indices of the Eastern bluefin tuna from data
collected in the Balearic Sea (Western Mediterranean). We also investigate the effects on the
index caused from having differences in the total sampled area among years. We used these
results to interpolate larval index values in years with not standard larval surveys but with some
ichthyoplankton surveys available, and to propose a “revised version” of the index providing
parameters of uncertainty
Seasonal Niche Partitioning of Surface Temperate Open Ocean Prokaryotic Communities
Surface microbial communities are exposed to seasonally changing environmental conditions, resulting in recurring patterns of community composition. However, knowledge on temporal dynamics of open ocean microbial communities remains scarce. Seasonal patterns and associations of taxa and oligotypes from surface and chlorophyll maximum layers in the western Mediterranean Sea were studied over a 2-year period. Summer stratification versus winter mixing governed not only the prokaryotic community composition and diversity but also the temporal dynamics and co-occurrence association networks of oligotypes. Flavobacteriales, Rhodobacterales, SAR11, SAR86, and Synechococcales oligotypes exhibited contrasting seasonal dynamics, and consequently, specific microbial assemblages and potential inter-oligotype connections characterized the different seasons. In addition, oligotypes composition and dynamics differed between surface and deep chlorophyll maximum (DCM) prokaryotic communities, indicating depth-related environmental gradients as a major factor affecting association networks between closely related taxa. Taken together, the seasonal and depth specialization of oligotypes suggest temporal dynamics of community composition and metabolism, influencing ecosystem function and global biogeochemical cycles. Moreover, our results indicate highly specific associations between microbes, pointing to keystone ecotypes and fine-tuning of the microbes realized niche.En prens
Dynamics of actively dividing prokaryotes in the western Mediterranean Sea
Microbial community metabolism and functionality play a key role modulating global biogeochemical
processes. However, the metabolic activities and contribution of actively growing prokaryotes to
ecosystem energy fluxes remain underexplored. Here we describe the temporal and spatial dynamics
of active prokaryotes in the different water masses of the Mediterranean Sea using a combination
of bromodeoxyuridine labelling and 16S rRNA gene Illumina sequencing. Bulk and actively dividing
prokaryotic communities were drastically different and depth stratified. Alteromonadales were rare
in bulk communities (contributing 0.1% on average) but dominated the actively dividing community
throughout the overall water column (28% on average). Moreover, temporal variability of actively
dividing Alteromonadales oligotypes was evinced. SAR86, Actinomarinales and Rhodobacterales
contributed on average 3–3.4% each to the bulk and 11, 8.4 and 8.5% to the actively dividing
communities in the epipelagic zone, respectively. SAR11 and Nitrosopumilales contributed less
to the actively dividing than to the bulk communities during all the study period. Noticeably, the
large contribution of these two taxa to the total prokaryotic communities (23% SAR11 and 26%
Nitrosopumilales), especially in the meso- and bathypelagic zones, results in important contributions
to actively dividing communities (11% SAR11 and 12% Nitrosopumilales). The intense temporal and
spatial variability of actively dividing communities revealed in this study strengthen the view of a
highly dynamic deep ocean. Our results suggest that some rare or low abundant phylotypes from
surface layers down to the deep sea can disproportionally contribute to the activity of the prokaryotic
communities, exhibiting a more dynamic response to environmental changes than other abundant
phylotypes, emphasizing the role they might have in community metabolism and biogeochemical
processes.This research has been supported by RADMED-TRES (2015–2019) and ATHAPOC (CTM2014-54374-R) projects, funded by the Spanish Institute of Oceanography and the Spanish Ministry of Economy and Competitiveness, respectively. CM was supported by pre-doctoral FPI fellowship from Conselleria d’Innovació, Recerca i Turisme of the regional Government of the Balearic Islands, co-financed by the European Social Fund as part of the FSE 2014-2020 operational program.Postprin
Atmosphere-Space Interactions Monitor (ASIM): State of the Art
Atmosphere-Space Interactions Monitor (ASIM) mission is an ESA pay load which will be installed in the Columbus module of the International Space Station (ISS). ASIM is optimized to the observation and monitoring of luminescent phenomena in the upper atmosphere, the so called Transient Luminous Event (TLEs) and Terrestrial Gamma Ray Flashes(TGFs). Both TLEs and TGFs have been discovered recently (past two decades) and opened a new field of research in high energetic phenomena in the atmosphere. We will review the capabilities of ASIM and how it will help researchers to gain deeper knowledge of TGFs, TLEs, their inter-relationship and how they are linked to severe thunderstorms and the phenomena of lightning
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