33 resultados para Batz
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"Termin: Dienstag, den 10. Juni 1884."
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Context. Classical Be stars are rapid rotators of spectral type late O to early A and luminosity class V-III, which exhibit Balmer emission lines and often a near infrared excess originating in an equatorially concentrated circumstellar envelope, both produced by sporadic mass ejection episodes. The causes of the abnormal mass loss (the so-called Be phenomenon) are as yet unknown. Aims. For the first time, we can now study in detail Be stars outside the Earth's atmosphere with sufficient temporal resolution. We investigate the variability of the Be Star CoRoT-ID 102761769 observed with the CoRoT satellite in the exoplanet field during the initial run. Methods. One low-resolution spectrum of the star was obtained with the INT telescope at the Observatorio del Roque de los Muchachos. A time series analysis was performed using both cleanest and singular spectrum analysis algorithms to the CoRoT light curve. To identify the pulsation modes of the observed frequencies, we computed a set of models representative of CoRoT-ID 102761769 by varying its main physical parameters inside the uncertainties discussed. Results. We found two close frequencies related to the star. They are 2.465 c d(-1) (28.5 mu Hz) and 2.441 c d(-1) (28.2 mu Hz). The precision to which those frequencies were found is 0.018 c d(-1) (0.2 mu Hz). The projected stellar rotation was estimated to be 120 km s(-1) from the Fourier transform of spectral lines. If CoRoT-ID 102761769 is a typical Galactic Be star it rotates near the critical velocity. The critical rotation frequency of a typical B5-6 star is about 3.5 c d(-1) (40.5 mu Hz), which implies that the above frequencies are really caused by stellar pulsations rather than star's rotation.
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Context. We present spectroscopic ground-based observations of the early Be star HD 49330 obtained simultaneously with the CoRoT-LRA1 run just before the burst observed in the CoRoT data. Aims. Ground-based spectroscopic observations of the early Be star HD 49330 obtained during the precursor phase and just before the start of an outburst allow us to disantangle stellar and circumstellar contributions and identify modes of stellar pulsations in this rapidly rotating star. Methods. Time series analysis (TSA) is performed on photospheric line profiles of He I and Si III by means of the least squares method. Results. We find two main frequencies f1 = 11.86 c d(-1) and f2 = 16.89 c d(-1) which can be associated with high order p-mode pulsations. We also detect a frequency f3 = 1.51 c d(-1) which can be associated with a low order g-mode. Moreover we show that the stellar line profile variability changed over the spectroscopic run. These results are in agreement with the results of the CoRoT data analysis, as shown in Huat et al. (2009). Conclusions. Our study of mid-and short-term spectroscopic variability allows the identification of p-and g-modes in HD 49330. It also allows us to display changes in the line profile variability before the start of an outburst. This brings new constraints for the seimic modelling of this star.
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Context. The presence of pulsations in late-type Be stars is still a matter of controversy. It constitutes an important issue to establish the relationship between non-radial pulsations and the mass-loss mechanism in Be stars. Aims. To contribute to this discussion, we analyse the photometric time series of the B8IVe star HD 50 209 observed by the CoRoT mission in the seismology field. Methods. We use standard Fourier techniques and linear and non-linear least squares fitting methods to analyse the CoRoT light curve. In addition, we applied detailed modelling of high-resolution spectra to obtain the fundamental physical parameters of the star. Results. We have found four frequencies which correspond to gravity modes with azimuthal order m = 0,-1,-2,-3 with the same pulsational frequency in the co-rotating frame. We also found a rotational period with a frequency of 0.679 cd(-1) (7.754 mu Hz). Conclusions. HD 50 209 is a pulsating Be star as expected from its position in the HR diagram, close to the SPB instability strip.
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Context. The origin of the short-term variability in Be stars remains a matter of controversy. Pulsations and rotational modulation are the components of the favored hypothesis. Aims. We present our analysis of CoRoT data of the B8IIIe star HD 175869 observed during the first short run in the center direction (SRC1). Methods. We review both the instrumental effects visible in the CoRoT light curve and the analysis methods used by the CoRoT Be team. We applied these methods to the CoRoT light curve of the star HD 175869. A search for line-profile variations in the spectroscopic data was also performed. We also searched for a magnetic field, by applying the LSD technique to spectropolarimetric data. Results. The light curve exhibits low-amplitude variations of the order of 300 mu mag with a double wave shape. A frequency within the range determined for the rotational frequency and 6 of its harmonics are detected. The main frequency and its first harmonic exhibit amplitude variations of a few days. Other significant frequencies of low-amplitude from 25 to a few mu mag are also found. The analysis of line profiles from ground-based spectroscopic data does not detect any variation. In addition, no Zeeman signature was found. Conclusions. Inhomogeneities caused by stellar activity in or just above the photosphere are proposed to produce the photometric variability detected by CoRoT in the Be star HD 175869. The hypothesis that non-radial pulsations are the origin of these variations cannot be excluded.
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Context. HD 181231 is a B5IVe star, which has been observed with the CoRoT satellite during similar to 5 consecutive months and simultaneously from the ground in spectroscopy and spectropolarimetry. Aims. By analysing these data, we aim to detect and characterize as many pulsation frequencies as possible, to search for the presence of beating effects possibly at the origin of the Be phenomenon. Our results will also provide a basis for seismic modelling. Methods. The fundamental parameters of the star are determined from spectral fitting and from the study of the circumstellar emission. The CoRoT photometric data and ground-based spectroscopy are analysed using several Fourier techniques: CLEAN-NG, PASPER, and TISAFT, as well as a time-frequency technique. A search for a magnetic field is performed by applying the LSD technique to the spectropolarimetric data. Results. We find that HD 181231 is a B5IVe star seen with an inclination of similar to 45 degrees. No magnetic field is detected in its photosphere. We detect at least 10 independent significant frequencies of variations among the 54 detected frequencies, interpreted in terms of non-radial pulsation modes and rotation. Two longer-term variations are also detected: one at similar to 14 days resulting from a beating effect between the two main frequencies of short-term variations, the other at similar to 116 days due either to a beating of frequencies or to a zonal pulsation mode. Conclusions. Our analysis of the CoRoT light curve and ground-based spectroscopic data of HD 181231 has led to the determination of the fundamental and pulsational parameters of the star, including beating effects. This will allow a precise seismic modelling of this star.
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Context. Be stars undergo outbursts producing a circumstellar disk from the ejected material. The beating of non-radial pulsations has been put forward as a possible mechanism of ejection. Aims. We analyze the pulsational behavior of the early B0.5IVe star HD 49330 observed during the first CoRoT long run towards the Galactical anticenter (LRA1). This Be star is located close to the lower edge of the beta Cephei instability strip in the HR diagram and showed a 0.03 mag outburst during the CoRoT observations. It is thus an ideal case for testing the aforementioned hypothesis. Methods. We analyze the CoRoT light curve of HD 49330 using Fourier methods and non-linear least square fitting. Results. In this star, we find pulsation modes typical of beta Cep stars (p modes) and SPB stars (g modes) with amplitude variations along the run directly correlated with the outburst. These results provide new clues about the origin of the Be phenomenon as well as strong constraints on the seismic modelling of Be stars.
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PURPOSE: Few studies compare the variabilities that characterize environmental (EM) and biological monitoring (BM) data. Indeed, comparing their respective variabilities can help to identify the best strategy for evaluating occupational exposure. The objective of this study is to quantify the biological variability associated with 18 bio-indicators currently used in work environments. METHOD: Intra-individual (BV(intra)), inter-individual (BV(inter)), and total biological variability (BV(total)) were quantified using validated physiologically based toxicokinetic (PBTK) models coupled with Monte Carlo simulations. Two environmental exposure profiles with different levels of variability were considered (GSD of 1.5 and 2.0). RESULTS: PBTK models coupled with Monte Carlo simulations were successfully used to predict the biological variability of biological exposure indicators. The predicted values follow a lognormal distribution, characterized by GSD ranging from 1.1 to 2.3. Our results show that there is a link between biological variability and the half-life of bio-indicators, since BV(intra) and BV(total) both decrease as the biological indicator half-lives increase. BV(intra) is always lower than the variability in the air concentrations. On an individual basis, this means that the variability associated with the measurement of biological indicators is always lower than the variability characterizing airborne levels of contaminants. For a group of workers, BM is less variable than EM for bio-indicators with half-lives longer than 10-15 h. CONCLUSION: The variability data obtained in the present study can be useful in the development of BM strategies for exposure assessment and can be used to calculate the number of samples required for guiding industrial hygienists or medical doctors in decision-making.
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Biological monitoring of occupational exposure is characterized by important variability, due both to variability in the environment and to biological differences between workers. A quantitative description and understanding of this variability is important for a dependable application of biological monitoring. This work describes this variability,using a toxicokinetic model, for a large range of chemicals for which reference biological reference values exist. A toxicokinetic compartmental model describing both the parent compound and its metabolites was used. For each chemical, compartments were given physiological meaning. Models were elaborated based on physiological, physicochemical, and biochemical data when available, and on half-lives and central compartment concentrations when not available. Fourteen chemicals were studied (arsenic, cadmium, carbon monoxide, chromium, cobalt, ethylbenzene, ethyleneglycol monomethylether, fluorides, lead, mercury, methyl isobutyl ketone, penthachlorophenol, phenol, and toluene), representing 20 biological indicators. Occupational exposures were simulated using Monte Carlo techniques with realistic distributions of both individual physiological parameters and exposure conditions. Resulting biological indicator levels were then analyzed to identify the contribution of environmental and biological variability to total variability. Comparison of predicted biological indicator levels with biological exposure limits showed a high correlation with the model for 19 out of 20 indicators. Variability associated with changes in exposure levels (GSD of 1.5 and 2.0) is shown to be mainly influenced by the kinetics of the biological indicator. Thus, with regard to variability, we can conclude that, for the 14 chemicals modeled, biological monitoring would be preferable to air monitoring. For short half-lives (less than 7 hr), this is very similar to the environmental variability. However, for longer half-lives, estimated variability decreased. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: tables detailing the CBTK models for all 14 chemicals and the symbol nomenclature that was used.] [Authors]
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BACKGROUND/AIMS: Thiazolidinediones (TZDs, like rosiglitazone (RGZ)) are peroxisome proliferator-activated receptor γ (PPARγ) agonists used to treat type 2 diabetes. Clinical limitations include TZD-induced fluid retention and body weight (BW) increase, which are inhibited by amiloride, an epithelial-sodium channel (ENaC) blocker. RGZ-induced fluid retention is maintained in mice with αENaC knockdown in the collecting duct (CD). Since ENaC in the connecting tubule (CNT) rather than in CD appears to be critical for normal NaCl retention, we aimed to further explore the role of ENaC in CNT in RGZ-induced fluid retention. METHODS: Mice with conditional inactivation of αENaC in both CNT and CD were used (αENaC lox/lox AQP2-Cre; 'αENaC-CNT/CD-KO') and compared with littermate controls (αENaC lox/lox mice; 'WT'). BW was monitored and total body water (TBW) and extracellular fluid volume (ECF) were determined by bioelectrical impedance spectroscopy (BIS) before and after RGZ (320 mg/kg diet for 10 days). RESULTS: On regular NaCl diet, αENaC-CNT/CD-KO had normal BW, TBW, ECF, hematocrit, and plasma Na(+), K(+), and creatinine, associated with an increase in plasma aldosterone compared with WT. Challenging αENaC-CNT/CD-KO with a low NaCl diet unmasked impaired NaCl and K homeostasis, consistent with effective knockdown of αENaC. In WT, RGZ increased BW (+6.1%), TBW (+8.4%) and ECF (+10%), consistent with fluid retention. These changes were significantly attenuated in αENaC-CNT/CD-KO (+3.4, 1.3, and 4.3%). CONCLUSION: Together with the previous studies, the current results are consistent with a role of αENaC in CNT in RGZ-induced fluid retention, which dovetails with the physiological relevance of ENaC in this segment. © 2014 S. Karger AG, Basel.
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OBJECTIVES: A survey was undertaken among Swiss occupational hygienists and other professionals to identify the different exposure assessment methods used, the contextual parameters observed and the uses, difficulties and possible developments of exposure models for field application. METHODS: A questionnaire was mailed to 121 occupational hygienists, all members of the Swiss Occupational Hygiene Society. A shorter questionnaire was also sent to registered occupational physicians and selected safety specialists. Descriptive statistics and multivariate analyses were performed. RESULTS: The response rate for occupational hygienists was 60%. The so-called expert judgement appeared to be the most widely used method, but its efficiency and reliability were both judged with very low scores. Long-term sampling was perceived as the most efficient and reliable method. Various determinants of exposure, such as emission rate and work activity, were often considered important, even though they were not included in the exposure assessment processes. Near field local phenomena determinants were also judged important for operator exposure estimation. CONCLUSION: Exposure models should be improved to integrate factors which are more easily accessible to practitioners. Descriptors of emission and local phenomena should also be included.
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Waterproofing agents are widely used to protect leather and textiles in both domestic and occupational activities. An outbreak of acute respiratory syndrome following exposure to waterproofing sprays occurred during the winter 2002-2003 in Switzerland. About 180 cases were reported by the Swiss Toxicological Information Centre between October 2002 and March 2003, whereas fewer than 10 cases per year had been recorded previously. The reported cases involved three brands of sprays containing a common waterproofing mixture, that had undergone a formulation change in the months preceding the outbreak. A retrospective analysis was undertaken in collaboration with the Swiss Toxicological Information Centre and the Swiss Registries for Interstitial and Orphan Lung Diseases to clarify the circumstances and possible causes of the observed health effects. Individual exposure data were generated with questionnaires and experimental emission measurements. The collected data was used to conduct numeric simulation for 102 cases of exposure. A classical two-zone model was used to assess the aerosol dispersion in the near- and far-field during spraying. The resulting assessed dose and exposure levels obtained were spread on large scales, of several orders of magnitude. No dose-response relationship was found between exposure indicators and health effects indicators (perceived severity and clinical indicators). Weak relationships were found between unspecific inflammatory response indicators (leukocytes, C-reactive protein) and the maximal exposure concentration. The results obtained disclose a high interindividual response variability and suggest that some indirect mechanism(s) predominates in the respiratory disease occurrence. Furthermore, no threshold could be found to define a safe level of exposure. These findings suggest that the improvement of environmental exposure conditions during spraying alone does not constitute a sufficient measure to prevent future outbreaks of waterproofing spray toxicity. More efficient preventive measures are needed prior to the marketing and distribution of new waterproofing agents.
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Contient : 1 « Discours sur la mort du roy Henry [II] et succession du roy François » II. 22 juin à 19 juillet 1559. En italien. Minute ; 2 Sur la mort de François II et le commencement du règne de Charles IX. En italien. Minute ; 3 Première séance du conseil où fut résolue la convocation des États généraux d'Orléans. « Fontanablio, il 21 d'agosto 1560 ». En italien. Minute ; 4 « Interrogatoires de [Jean de Merei, dit] Poltrot, 21 fevrier 1562 ». Copie ; 5 Lettres d'«OTTAVIO FARNESE,... al cavalier Tiburtio Burty,... Da Parma, alli XII di febraro 1562 » ; 6 « Articoli mandati dal re CARLO IX al papa » Pie IV sur les réformes à introduire dans l'Église touchant les images, l'administration des sacrements, la messe. Janvier 1561 ; 7 Lettre de « CHARLES IX,... à mon cousin, le prince de Portian,... Escript au Mont de Marsan, le XXIe jour de may 1565 » ; 8 « Instruction à monseigneur le general d'Auvergne de l'ordre qu'il aura à tenir et observer et faire tenir et observer par ceulx qu'il commectera à la levée des douze cens mullets à batz que le roy a ordonné estre levez pour le service de son armée en païs d'Auvergne, et chargés de Lyon, Thoulouze, Montpelier et Provence... Faict à Fontainebleau, le XIIe jour de mars, l'an mil cinq cens cinquante sept ». Copie ; 9 « Roolle de la monstre et veue faicte en la ville de Riom en Auvergne, le treizeiesme may V.C. cinquante huict, du nombre et quantité de cinquante mulletz à batz, levez pour le service du roy aud. païs... presentez par devant Michel Veyny, seigneur d'Arbouze, general des finances en la generalité de Languedoc ». Copie ; 10 Ordonnance de payement desdits mulets. Copie ; 11 Reçu des vendeurs desdits mulets. Copie ; 12 « Reglement que le roi CHARLES [IX] voulut estre observé » pour « pourveoir à la garde et seureté de sa bonne ville de Paris... 18 nov. 1568 ». Minute ; 13 Lettre de « LOYS DE BOURBON, prince DE CONDE,... à monsieur le duc de Montpensier,... De ce camp, à La Fontayne, ce VIIIe decembre 1568 ». Copie ; 14 « Escrit difamatoire envoié de la part des huguenots ou de Mr le mareschal de Villevieille,... Melun, 1568, decembre », factum du prince DE CONDE contre « le cardinal de Lorraine et aultres pensionnaires du roy d'Espaigne, ses adherans » ; 15 « Copie d'un advis escrit de la main du Sr DE CARNAVALLET », sur les mesures à prendre pour empêcher les troupes du prince de Condé et de l'amiral de Coligni « de pouvoir joindre avec les Allemans » envoyés par le duc des Deux Ponts. « S. Mor, 5 janvier 1569 » ; 16 « Sur la Negotiation de la paix », préliminaires de la paix conclue à Saint Germain en Laye, le 8 août 1570, entre Charles IX et les protestants ; 17 « Copia d'una lettera di mons. CAPI LUPI, vescovo di Fano, al Sr duca d'Urbino. Di Roma, il 23 settembre 1571 ». En italien ; 18 « Discours de [LOUIS DE GONZAGUE, duc DE NEVERS], sur la maniere de bien governer les affaires du roy [Charles IX], qu'il a mis es mains de monseigneur le duc d'Anjou,... et de l'entreprise de la Floride pour luy... Chenonceau, ce 20 may 1572 ». Minute ; 19 Lettre de LOUIS DE GONZAGUE, duc DE NEVERS, gouverneur de Piémont, au roi Charles IX. « Estampes, dernier may 1572 » ; 20 « Trois Discours faits par [LOUIS DE GONZAGUE, duc DE NEVERS] et baillés à monsieur [le duc d'Anjou], sur les propositions que monseigneur l'admiral volloit faire pour induire le roy à faire la guere en Flandre... Paris, 19 juing 1572 ». Copie ; 21 Discours du duc DE NEVERS sur le même sujet. « 26 de juin 1572 ». Minute ; 22 Lettre de « LODOVICO GONZAGA », duc DE NEVERS, au roi Charles IX. « Ce 26 juign 1572 ». Minute ; 23 Avis motivé du duc DE NEVERS au roi Charles IX, pour le détourner d'entreprendre la guerre de Flandre. « 26 juin 1572 ». Minute ; 24 « Advis du mareschal DE TAVANES, par commandement du roy » Charles IX, avec même conclusion. « Paris, 26 juign 1572 ». Copie ; 25 « Discours comancé sur l'infidelité des Rochellois de la couronne de France, et come l'on s'y doit bien peu fier », commencement d'un mémoire rédigé par le duc DE NEVERS contre les protestants. « Paris, juillet 1572 ». Minute ; 26 « Copie d'un memoire de LODOVICO GONZAGA [duc DE NEVERS], doné à Monsieur [le duc d'Anjou] pour bailler au roy, par lequel est discouru bien amplement l'estat auquel se trovent les villes de [son] governement de Piemont... Paris, 8 aoust 1572 » ; 27 « Discours » du duc DE NEVERS « sur ce quy se pouroit faire à l'endroit dès huguenaulx reduis al la religion catolique et des autres opiniastres... Paris, 20 settembre 1572 ». Copie ; 28 « Discours et advis » du duc DE NEVERS, « comancé sur le reglement de la France et baillé au roy [Charles IX]... Paris, septembre 1572 ». Minute ; 29 « Instruction dressée » par le duc DE NEVERS, « pour supplier [le roi Charles IX] de faire haster les Suysses, et « l'argent » dont le duc d'Anjou avait « grandement affaire » pour le siége de La Rochelle. « La Guiche, 18 fevrier 1573 ». Copie ; 30 « Advis » du duc DE NEVERS, « doné à Monsieur [le duc d'Anjou], sur la depesche du capitaine Bourg », qui étant en contradiction avec celle donnée au « Sr de Crillon » pour le même objet, pouvait donner à l'amiral Honorat de Savoie lieu de penser qu'il y avait « peu de stabillité et de consideration aux depesches » dudit duc. « Chatelleraut, 23 febvrier 1573 ». Minute ; 31 Avis du duc DE NEVERS sur la conduite à tenir pour permettre au duc d'Anjou d'éviter et le blâmé des étrangers en accordant aux Rochellois une capitulation trop avantageuse et la colère du roi en refusant ladite capitulation. « 1 de fevrier 1573 ». Minute ; 32 Journal du siége de La Rochelle, du 11 février au 21 mars 1573 ; 33 « Responce du seigneur DE BIRON au memoire que monseigneur [le duc d'Aujou] luy a envoyé par le Sr de Beaulieu », relativement aux mesures prises pour faciliter les approches de La Rochelle. « Rochelle, 19 may 1573 » ; 34 « Coppie d'un memoire faict par monseigneur [le duc DE NEVERS] à Monsieur [le duc d'Anjou], frere du roy » Charles IX, relativement aux mesures à prendre pour préparer l'assaut d'un bastion de La Rochelle. « Au camp, 25 mars 1573 » ; 35 « Memoire pour interojer » relativement au même sujet. « Au camp, 26 mars 1573 ». Copie ; 36 Mémoire sur le même sujet. « Camp, 12 avril 1573 » ; 37 Mémoire du duc D'ANJOU, pour justifier les demandes de forces qu'il avait adressées au roi Charles IX et la lenteur des opérations du siége de La Rochelle. Fin de février 1573. Minute ; 38 Lettre de « HENRI [duc D'ANJOU]... à monsieur de Nevers,... May 1573 » ; 39 Lettre du duc DE NEVERS au duc d'Anjou. « De Lagor, 2 may 1573 ». Copie ; 40 Lettre du duc DE NEVERS « à monseigneur de Villeclerc,... De Lagor, 2 may 1573 ». Copie ; 41 Mesures à prendre pour le siége de La Rochelle. « May 1573 ». Copie ; 42 « Discours du duc DE NEVERS sur le traitté que Monsieur [le duc d'Anjou] veult faire aux Rochellois pour pacifier les chauses, lequel contient qu'il ne fault leur accorder la pais, ains les recevoir à mercy et à discretion... Du camp, ce XIe may 1573 ». Minute ; 43 Lettre de CATHERINE DE MEDICIS au duc de Nevers. « De Boullongne, ce sixme juillet 1573 ». Copie ; 44 Lettre de « HENRY [duc D'ANJOU]... à monsieur le duc de Nevers,... Juin 1573 » ; 45 « Discours » du duc DE NEVERS « sur l'entrée aux affaires du roy, baillé au roy de Poullogne [Henri, duc d'Anjou]... Tours, 21 julliet 1573 ». Minute ; 46 « Discours doné par monseigneur le conte DE RETZ au roy de Poullogne [Henri, duc d'Anjou], sur le voiage de La Rochelle et reglement du roiaulme de France, pour bailler au roy [Charles IX]... 30 de juillet 1573 ». Copie ; 47 « Aultre Discours ensuivant l'aultre de monseigneur le conte de Retz,... Fin juillet 1573 ». Copie ; 48 Procès-verbal de la lecture en conseil d'un mémoire de HENRI, duc D'ANJOU et roi de Pologne, sur le fait de La Rochelle et le rétablissement des affaires du royaume de France. Du 2 au 14 août 1573. Minute ; 49 « Article de la justice, fait par M. DE CHIVERNY sur [les] memoires » du duc de Nevers. Sujet traité par Henri, duc d'Anjou, roi de Pologne, dans son discours sur le rétablissement des affaires du royaume de France. « Madril, 6 aoust 1573 ». Copie ; 50 « Discours presenté au roy [Charles IX] par le roy de Pollongne, son frere, touchant sommairement son voiage faict à La Rochelle et aultres choses concernant le bien et repos de son royaulme ». Rédigé par le duc DE NEVERS. « Paris, 14 aoust 1573 ». Copie ; 51 « Discours en voyé à la royne mere du roy [Charles IX par monseigneur [le duc DE NEVERS]... Au bois de Vincennes, 20 aoust 1573 ». Pour rassurer Catherine de Médicis contre la crainte d'une éme???ute dans Paris. Copie ; 52 « Advis » du duc DE NEVERS, « doné à monseigneur [le duc d'Anjou], sur la descente des Anglois [envoyés au secours des Rochellois]... Niort, 3 febvrier 1573 ». Minute ; 53 « Coppie d'une lectre escripte par monseigneur [le duc DE NEVERS] à monsieur de Chiverny,... De Vuormes, ce XIIIIe decembre 1573 »
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Context. Be stars are rapidly rotating stars with a circumstellar decretion disk. They usually undergo pressure and/or gravity pulsation modes excited by the kappa-mechanism, i.e. an effect of the opacity of iron-peak elements in the envelope of the star. In the Milky Way, p-modes are observed in stars that are hotter than or equal to the B3 spectral type, while g-modes are observed at the B2 spectral type and cooler. Aims. We observed a B0IVe star, HD51452, with the high-precision, high-cadence photometric CoRoT satellite and high-resolution, ground-based HARPS and SOPHIE spectrographs to study its pulsations in great detail. We also used the lower resolution spectra available in the BeSS database. Methods. We analyzed the CoRoT and spectroscopic data with several methods: CLEAN-NG, FREQFIND, and a sliding window method. We also analyzed spectral quantities, such as the violet over red (V/R) emission variations, to obtain information about the variation in the circumstellar environment. We calculated a stellar structure model with the ESTER code to test the various interpretation of the results. Results. We detect 189 frequencies of variations in the CoRoT light curve in the range between 0 and 4.5 c d(-1). The main frequencies are also recovered in the spectroscopic data. In particular we find that HD51452 undergoes gravito-inertial modes that are not in the domain of those excited by the kappa-mechanism. We propose that these are stochastic modes excited in the convective zones and that at least some of them are a multiplet of r-modes (i.e. subinertial modes mainly driven by the Coriolis acceleration). Stochastically excited gravito-inertial modes had never been observed in any star, and theory predicted that their very low amplitudes would be undetectable even with CoRoT. We suggest that the amplitudes are enhanced in HD51452 because of the very rapid stellar rotation. In addition, we find that the amplitude variations of these modes are related to the occurrence of minor outbursts. Conclusions. Thanks to CoRoT data, we have detected a new kind of pulsations in HD51452, which are stochastically excited gravito-inertial modes, probably due to its very rapid rotation. These modes are probably also present in other rapidly rotating hot Be stars.