bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing a methodology to support the evolution of System of Systems using risk analysis
Authors: Lock Russell
Published: July 2011

The potential for uncontrolled evolution of member systems is one of the most significant challenges facing SoS (System of Systems) management. Lack of control in evolution makes organizations more inefficient, raises costs, and can affect their ability to adapt quickly to changing circumstance. SoS bring together individual systems to fulfill shared goals, but the systems are likely to have been developed independently, and to different development and operational standards. Member systems retain much of their autonomy, along with their motivations and goals. This increases the risk of decisions relating to evolution being taken unilaterally within member systems, potentially to the detriment of the stability, efficiency and dependability of the SoS. This paper proposes a methodology to support non specialist end users in the identification, organization and discussion of information required to manage SoS evolution, and uses a modified form of HAZOPS (Hazard and Operability Study) to analyze the associated risks of evolution. The paper evaluates the methodology using a case study based on a recent RAF (Royal Air Force) Nimrod air crash, the official investigation into which showed severe failings in the operation of the Nimrod SoS. The paper concludes that the methodology proposed would provide valuable support to SoS evolution processes, and discusses future directions for the research. © 2011 Wiley Periodicals, Inc. Syst Eng
Learning from failure in systems engineering: A panel discussion
Authors: Slegers Nathan J. , Kadish Ronald T. , Payton Gary E. , Thomas John , Griffin Michael D. , Dumbacher Dan
Published: July 2011

This paper summarizes the discussion of the Learning from Failure in Systems Engineering panel that was held in Huntsville, AL on November 8, 2010. The panel objective was to discuss how systems engineers respond to and learn from failure and identify future directions important to the community. The panel consisted of four representatives with experience in government, industry, and academia: (1) Ronald Kadish from Booz Allen Hamilton and former director of the Missile Defense Agency, (2) Gary Payton, retired Deputy Under Secretary of the Air Force for Space Programs, (3) John Thomas from Booz Allen Hamilton and President‐elect of INCOSE, and (4) Michael Griffin from the University of Alabama, Huntsville and former NASA Administrator. Each panelist was asked to (i) provide an opening statement and elaborate on their experience with failure, (ii) describe when failure is appropriate, (iii) describe how we learn and react to failure, and (iv) identify and discuss techniques to improve how systems engineers react to failure. Several common themes arose from the discussion including: failure is an option, the importance of failure to allow reassessment, and more process is not the solution. Each of these is discussed in turn along with future directions identified for reacting to and learning from failure. © 2011 Wiley Periodicals, Inc. Syst Eng
Guillain–Barré Syndrome Mimicking Nerve Injury after Total Hip Arthroplasty
Authors: Heyworth Benton E. , Fabricant Peter D. , Pizzurro Mark M. , Beksac Burak , Salvati Eduardo A.
Published: July 2011

Background

Guillain–Barré syndrome (GBS) is a rare, acute, inflammatory demyelinating polyneuropathy with a presentation of progressive ascending motor weakness of the extremities, which may extend to the respiratory muscles and require mechanical support.

Case Description

This case describes a healthy male who developed GBS 1 week following otherwise an uncomplicated bilateral total hip arthroplasty surgery. The diagnosis was made based on physical exam significant for bilateral lower extremity weakness and diffuse arreflexia, and confirmed by nerve conduction studies. There were no effects on respiratory function, and the patient underwent a gradual recovery, with near complete return of motor function by 10 weeks following surgery and no functional deficits at 1 year following surgery. Functional activity levels are maintained 4 years postoperatively.

Literature Review

A literature review is presented. While GBS has been described in the literature following several different forms of surgery and anesthesia, cases after orthopedic surgery are exceedingly rare.

Purposes and Clinical Relevance

This case demonstrates that GBS may occur following orthopedic, including total joint arthroplasty, surgery. The presentation of GBS can be variable, but the hallmarks are areflexia and diffuse ascending weakness, with or without sensory symptoms. Rapid diagnosis and treatment are critical for preventing disability and life-threatening sequelae.
Biology, immature and adult morphology, and molecular characterization of a new species of the genusEntedon(Hymenoptera: Eulophidae) associated with the invasive pestSpecularius impressithorax(Coleoptera: Chrysomelidae, Bruchinae) onErythrinaplants
Authors: Gumovsky A.V. , Ramadan M.M.
Published: July 2011

Entedon erythrinaesp. n. (Hymenoptera: Eulophidae), a gregarious egg-larval endoparasitoid of the Erythrina bruchineSpecularius impressithorax, an invasive pest of the coral tree seeds (Erythrinaspp.), is described from the Hawaiian Islands and Africa (South Africa, Tanzania and Mozambique). The biology and morphology of preimaginal stages of this new species are described in details.

It is remarkable that the early embryo of the parasitoid represents a mass of undifferentiated cells surrounded by a peculiar membrane formed by the peripheral enlarged polygonal cells. The young larva developing inside this membrane corresponds morphologically to the second instar of congeneric species. Various peculiarities of the parasitoid-host relationships in gregarious and solitaryEntedonparasitoids are discussed. The DNA sequences of 28S D2 (nuclear), Cytochrome Oxidase I (COI, mitochondrial) and Cytochrome B (CytB, mitochondrial) genes are provided for this new species and compared with the sequences of some other Afrotropical and Palearctic species of the genus.
Intranasal delivery of drugs to eustachian tube orifice
Authors: Karagama Y G , Rashid M , Lancaster J L , Karkanevatos A , William R S
Published: July 2011

Background:

Intranasal medication administration which aims to deliver to the eustachian tube orifice has been adopted for the management of a number of otological conditions, acting via a reduction in tubal oedema and improved ventilation. Evidence for the optimal head position for such drug administration is limited. We compared four different positions and also assessed spray versus drop formulation, to determine optimal delivery conditions.

Methods:

Prospective, five-period, cross-over study using methylene blue dyed saline in a drops or spray container. Five healthy volunteers tested the Mygind, Ragan, Mecca and ‘head back’ head positions. Nasal spray drug delivery in the most effective head position was then compared with drops drug delivery (administered in the head back position). Intranasal delivery was assessed photographically using a 30° rigid naso-endoscope.

Results:

Maximal nasal drops delivery was achieved with the Mygind and Ragan positions. Drops were more successful than spray in reaching the eustachian tube orifice.

Conclusion:

The Mygind and Ragan positions are best for eustachian tube orifice drug delivery, and drops preparations are better than spray preparations.
The contributions of the lips and the tongue to the diachronic fronting of high back vowels in Standard Southern British English
Authors: Harrington Jonathan , Kleber Felicitas , Reubold Ulrich
Published: July 2011

Recent acoustic studies have provided evidence that /u/ (goose) and /ʊ/ (foot) have fronted in the standard accent of England in the last fifty years, but what is less clear is whether this fronting is due entirely to a repositioning of the tongue or whether it has been accompanied by an unrounding of the lips. Four experiments were carried out to shed light on this issue. An acoustic study of anticipatory coarticulation in /s/ in the first of these suggested a similar degree of lip-protrusion for young speakers whose F2 of /u/ was raised compared with that of older speakers. Compatibly, judgments of lip-rounding elicited from cross-dubbed auditory-visual stimuli and an analysis of lip movement showed young speakers' /u/ to be produced with rounded lips. Their tongue positions and movements in the final experiment were found to be almost as advanced for /u/ as for /i/ (fleece) and nearer to a central position for lax /ʊ/ (foot). Taken together, these results confirm firstly, that the diachronic shift in /u/ has involved a realignment of the tongue, but not of the lips; and secondly, that the diachronic shift in /ʊ/ is likely to be a more recent innovation than that of its tense counterpart.
Notes on the chart of the International Phonetic Alphabet in Chinese
Authors: Hu Fang
Published: July 2011

The idea of having a version of the IPA chart in Chinese was initiated by a group of Chinese phoneticians and dialectologists in 2006. The situation that existed at the time was that the IPA terms used in mainstream Chinese textbooks and in classrooms were still following various older versions of the chart and principles. For instance, there were no approximants in the consonant chart; instead, the Chinese translation of the term ‘frictionless continuant’ was still listed in the consonant chart. After the revised IPA chart was released in 2005, Chinese phoneticians and dialectologists considered it a good opportunity to promote the updated IPA terminology in Chinese, reflected in a Chinese version of the chart. In the winter of 2006, the Phonetic Association of China organized an advisory committee and a working committee to undertake the translation. Following some months of e-mail communications among committee members, a meeting was organized at the Institute of Linguistics, Chinese Academy of Social Sciences, on 7 January 2007. Five members of the advisory committee and seven members of the working committee participated in the final discussion. At the meeting in Beijing, we worked out the 2007 version of the IPA chart in Chinese that is reproduced here. This chart was first published in the first issue of the Chinese journal Fangyan 方 言 [Dialect] in 2007. The copyright symbol at the top of the chart indicates that the Chinese version is a work of the Phonetic Association of China, which is, officially speaking, a member of the Linguistic Society of China. The intention of the Association in disseminating the chart has been to unify and clarify the traditions of Chinese phonetic usage, to standardize Chinese terminology for referring to speech sounds and categories, and to communicate and promote the knowledge of IPA practices to Chinese-speaking society.
Kera
Authors: Pearce Mary
Published: July 2011

Kera is an Eastern Chadic language spoken by about 50,000 people in southwestern Chad, south of the town of Fianga, and in major towns of Cameroon and Chad. Most Kera speakers would claim to speak a standard variety of Kera although there is some variation depending on gender and location. The differences involve the relationship between tone and voicing, the number of contrastive tones and the presence or absence of a voicing contrast. Women are more conservative than men in the use of tone in rural settings and more innovative than men in urban settings (Pearce 2009). Previous literature on Kera includes Ebert (1975, 1976, 1979) and Pearce (1999, 2006a, b, c, 2007a, 2008, 2009).
The acoustic consequences of phonation and tone interactions in Jalapa Mazatec
Authors: Garellek Marc , Keating Patricia
Published: July 2011

San Felipe Jalapa de Díaz (Jalapa) Mazatec is unusual in possessing a three-way phonation contrast and three-way level tone contrast independent of phonation. This study investigates the acoustics of how phonation and tone interact in this language, and how such interactions are maintained across variables like speaker sex, vowel timecourse, and presence of aspiration in the onset. Using a large number of words from the recordings of Mazatec made by Paul Kirk and Peter Ladefoged in the 1980s and 1990s, the results of our acoustic and statistical analysis support the claim that spectral measures like H1-H2 and mid-range spectral measures like H1-A2 best distinguish each phonation type, though other measures like Cepstral Peak Prominence are important as well. This is true regardless of tone and speaker sex. The phonation type contrasts are strongest in the first third of the vowel and then weaken towards the end. Although the tone categories remain distinct from one another in terms of F0 throughout the vowel, for laryngealized phonation the tone contrast in F0 is partially lost in the initial third. Consistent with phonological work on languages that cross-classify tone and phonation type (i.e. ‘laryngeally complex’ languages, Silverman 1997), this study shows that the complex orthogonal three-way phonation and tone contrasts do remain acoustically distinct according to the measures studied, despite partial neutralizations in any given measure.
Diversification of Antarctic tourism: the case of a scuba diving expedition
Authors: Lamers Machiel , Gelter Hans
Published: July 2011

Tourism in Antarctica has grown substantially over recent decades and has diversified into different activities and modes of transport. This paper presents a first attempt to explore the implications of this diversification trend for Antarctic tourist experiences, wildlife and onsite management. Evidence from a passenger survey, participatory observations and expert interviews using video elicitation has been collected during, and in the context of, a diving expedition cruise. The data suggests that significant differences can be detected in the way divers and non-divers experience aspects of the trip, most notably regarding guides. The results also indicate that diverse activities generate a broader variance in attitudes and behaviours, which may have repercussions for wildlife, site use and onsite management. Given the diversification trend it is timely and necessary to revisit and consistently enforce site guidelines and visitor guidelines with an eye on multi-activity trips. In addition, further studies on the implications of this trend are needed by means of case studies, surveys looking at a wider range of tourist trips, and monitoring programmes assessing wildlife behaviour and impacts.
Is p53 controlling spermatogenesis in male mice with the deletion on the Y chromosome?
Authors: Lech Tomasz , Golas Aniela , Styrna Jozefa
Published: July 2011

The aim of the study was to evaluate the influence of the chromosome Y structure and Trp53 genotype on semen quality parameters. Mice with partial deletion of the Y chromosome (B10.BR-Ydel) have severely altered sperm head morphology when compared with males that possess the complete Y chromosome (B10.BR). Control males from B10.BR and B10.BR-Ydel mice, and mutant males from B10.BR-p53−/− and B10.BR-Ydel-p53−/− experimental groups were used. We assessed testis weight, sperm head abnormalities, viability of spermatozoa (eosin test), percentage of motile and immature sperm, and performed a hypo-osmotic test to detect abnormal tail membrane integrity. Sperm morphology and maturation were controlled by the genes within the deleted region of the Y chromosome. Testis weight was higher in the mutants than in the control males, possibly due to cell accumulation in Trp53-deficient males as the concentration of sperm was significantly increased in the mutants. An elevated percentage of abnormal sperm was noted in B10.BR-p53−/− and B10.BR-Ydel-p53−/− male mice. We suggest that, in Trp53-deficient mice, the sperm cells that escape apoptosis are the ones that have abnormal morphology. The only sperm quality parameter affected by the interplay between Trp53 and chromosome Y genes was sperm motility, which was elevated in B10.BR-p53−/− males, but remained unchanged in B10.BR-Ydel-p53−/− males.
In vitro development of nuclear transfer embryos derived from porcine embryonic germ cells and their descendent neural precursor cells
Authors: Shin Susa , Ahn Kwang Sung , Choi Seong-Jun , Heo Soon Young , Shim Hosup
Published: July 2011

Undifferentiated stem cells may support a greater development of cloned embryos compared with differentiated cell types due to their ease of reprogramming during the nuclear transfer (NT) process. Hence, stem cells may be more suitable as nuclear donor cells for NT procedures than are somatic cells. Embryonic germ (EG) cells are undifferentiated stem cells that are isolated from cultured primordial germ cells (PGC) and can differentiate into several cell types. In this study, the in vitro development of NT embryos using porcine EG cells and their derivative neural precursor (NP) cells was investigated, thus eliminating any variation in genetic differences. The rates of fusion did not differ between NT embryos from EG and NP cells; however, the rate of cleavage in NT embryos derived from EG cells was significantly higher (p < 0.05) than that from NP cells (141/247 [57.1%] vs. 105/228 [46.1%]). Similarly, the rate of blastocyst development was significantly higher (P < 0.05) in NT using EG cells than the rate using NP cells (43/247 [17.4%] vs. 18/228 [7.9%]). The results obtained from the present study in pigs demonstrate a reduced capability for nuclear donor cells to be reprogrammed following the differentiation of porcine EG cells. Undifferentiated EG cells may be more amenable to reprogramming after reconstruction compared with differentiated somatic cells.
Active OB Stars - an introduction
Authors: Baade Dietrich , Rivinius Thomas , Štefl Stanislas , Martayan Christophe
Published: July 2011

Identifying seven activities and activity-carrying properties and nine classes of Active OB Stars, the OB Star Activity Matrix is constructed to map the parameter space. On its basis, the occurrence and appearance of the main activities are described as a function of stellar class. Attention is also paid to selected combinations of activities with classes of Active OB Stars. Current issues are identified and suggestions are developed for future work and strategies.
Rapid rotation and mixing in active OB stars – Physical processes
Authors: Zahn Jean-Paul
Published: July 2011

In the standard description of stellar interiors, O and B stars possess a thoroughly mixed convective core surrounded by a stable radiative envelope in which no mixing occurs. But as is well known, this model disagrees strongly with the spectroscopic diagnostic of these stars, which reveals the presence at their surface of chemical elements that have been synthesized in the core. Hence the radiation zone must be the seat of some mild mixing mechanisms. The most likely to operate there are linked with the rotation: these are the shear instabilites triggered by the differential rotation, and the meridional circulation caused by the changes in the rotation profile accompanying the non-homologous evolution of the star. In addition to these hydrodynamical processes, magnetic stresses may play an important role in active stars, which host a magnetic field. These physical processes will be critically examined, together with some others that have been suggested.
3D MHD simulations of subsurface convection in OB stars
Authors: Cantiello Matteo , Braithwaite Jonathan , Brandenburg Axel , Del Sordo Fabio , Käpylä Petri , Langer Norbert
Published: July 2011

During their main sequence evolution, massive stars can develop convective regions very close to their surface. These regions are caused by an opacity peak associated with iron ionization. Cantiello et al. (2009) found a possible connection between the presence of sub-photospheric convective motions and small scale stochastic velocities in the photosphere of early-type stars. This supports a physical mechanism where microturbulence is caused by waves that are triggered by subsurface convection zones. They further suggest that clumping in the inner parts of the winds of OB stars could be related to subsurface convection, and that the convective layers may also be responsible for stochastic excitation of non-radial pulsations. Furthermore, magnetic fields produced in the iron convection zone could appear at the surface of such massive stars. Therefore subsurface convection could be responsible for the occurrence of observable phenomena such as line profile variability and discrete absorption components. These phenomena have been observed for decades, but still evade a clear theoretical explanation. Here we present preliminary results from 3D MHD simulations of such subsurface convection.
Rotation rates of massive stars in the Magellanic Clouds
Authors: Penny Laura R. , Gies Douglas R.
Published: July 2011

We present the results of our survey of the projected rotational velocities of 161 O-type stars in the Magellanic Clouds from archival FUSE observations. The evolved and unevolved samples from each environment are compared through the Kolmogorov-Smirnov test to determine if the distribution of equatorial rotational velocities is metallicity dependent for these massive objects. Stellar interior models predict that massive stars with SMC metallicity will have significantly reduced angular momentum loss on the main sequence compared to their Galactic counterparts. Our statistical results find some support for this prediction but also show that even at Galactic metallicity, evolved and unevolved massive stars have fairly similar fractions of stars with large V sin i. What is more compelling are the few evolved objects in the Magellanic Clouds with rotational velocities that approach or even exceed those predicted from the evolutionary models.
Massive stellar models: rotational evolution, metallicity effects
Authors: Ekström Sylvia , Georgy Cyril , Meynet Georges , Maeder André , Granada Anahí
Published: July 2011

The Be star phenomenon is related to fast rotation, although the cause of this fast rotation is not yet clearly established. The basic effects of fast rotation on the stellar structure are reviewed: oblateness, mixing, anisotropic winds. The processes governing the evolution of the equatorial velocity of a single star (transport mechanisms and mass loss) are presented, as well as their metallicity dependence. The theoretical results are compared to observations of B and Be stars in the Galaxy and the Magellanic Clouds.
About the Luminous Blue Variable He3-519
Authors: Hervé Anthony , Bouret Jean-Claude
Published: July 2011

Luminous Blue Variables (LBVs) are massive stars, in a transition phase, from being O-type stars and rapidly becoming Wolf-Rayet objects. LBVs possess powerful stellar winds, high luminosities and show photometric and spectroscopic variability. We present the stellar and wind parameters of He3-519 obtained by the modeling of UVES observations with the model atmosphere code CMFGEN. We compare our results to previous studies in order to find mid-time scale variability of the stellar parameters and finally, we use stellar evolution models to determine the evolutionary status of this star.
Models of classical Be stars with gravity darkening
Authors: McGill Meghan A. , Sigut T. A. Aaron. , Jones Carol E.
Published: July 2011

Classical Be stars are rapidly rotating, hot stars that possess an equatorial disk formed from gas released by the central star. The mechanism driving the stellar mass loss has yet to be fully explained, but the rapid rotation of the central B star is believed to be crucial. Rapid rotation also produces gravity darkening, and we have now extended our disk models to include these effects. In this contribution, we focus on the effect of gravity darkening on the thermal structure of a circumstellar disk.
Spectroscopic and interferometric approach for differential rotation in massive fast rotators
Authors: Zorec Juan , Frémat Yves , Delaa Omar , Domiciano de Souza Armando , Stee Philippe , Mourard Denis , Cidale Lydia S. , Martayan Christophe
Published: July 2011

The coupling between the convective region in the envelope and rotation can produce a surface latitudinal differential rotation that may induce changes of the stellar geometry and on the spectral line profiles that it may be scrutinized spectroscopically and by interferometry.
The MiMeS project: overview and current status
Authors: Wade Gregg A. , Alecian Evelyne , Bohlender David A. , Bouret Jean-Claude , Cohen David H. , Duez Vincent , Gagné Marc , Grunhut Jason H. , Henrichs Huib F. , Hill Nick R. , Kochukhov Oleg , Mathis Stéphane , Neiner Coralie , Oksala Mary E. , Owocki Stan , Petit Véronique , Shultz Matthew , Rivinius Thomas , Townsend Richard H. D. , Vink Jorick S. ,   the MiMeS collaboration
Published: July 2011

The Magnetism in Massive Stars (MiMeS) Project is a consensus collaboration among many of the foremost international researchers of the physics of hot, massive stars, with the basic aim of understanding the origin, evolution and impact of magnetic fields in these objects. At the time of writing, MiMeS Large Programs have acquired over 950 high-resolution polarised spectra of about 150 individual stars with spectral types from B5-O4, discovering new magnetic fields in a dozen hot, massive stars. The quality of this spectral and magnetic matériel is very high, and the Collaboration is keen to connect with colleagues capable of exploiting the data in new or unforeseen ways. In this paper we review the structure of the MiMeS observing programs and report the status of observations, data modeling and development of related theory.
Structure in the winds of O-Type stars: observations and inferences
Authors: Fullerton Alex W.
Published: July 2011

This review describes the observational evidence for structure in the winds of O-type stars due to large-scale perturbations and small-scale inhomogeneities. Despite considerable progress, a comprehensive theoretical framework that explains the origin. properties, and coexistence of wind structure on different spatial scales has yet to be constructed and incorporated into model atmosphere analyses. Consequently, it is not yet possible to assess the effect of non-stationary structures on different wind diagnostics in a rigorous way, with the result that accurate empirical determinations of mass-loss rates remain elusive.
Magnetic Doppler imaging of early-type stars
Authors: Kochukhov Oleg , Rivinius Thomas , Oksala Mary E. , Romanyuk Iosif
Published: July 2011

Doppler imaging of early-type magnetic stars is the most advanced method to interpret their line profile variations. DI allows us to study directly a complex interplay between chemical spots, magnetic fields, and the mass loss. Here we outline the general principles of the surface mapping of stars, discuss adaption of this technique to early-type stars and present several recent examples of the abundance and magnetic mapping performed for rapidly rotating early-B stars. In particular, we present the first Doppler images for the very fast rotating He-rich star HR 7355 and a reconstruction of magnetic field for the well-known Bp star σ Ori E. We also present new magnetic maps for the He-strong star HD 37776, which possesses one of the most complex magnetic field topologies among the upper main sequence stars.
Rigid Field Hydrodynamic simulations of the magnetosphere of σ Orionis E
Authors: Hill Nicholas R. , Townsend Richard H. D. , Cohen David H. , Gagné Marc
Published: July 2011

We present Rigid Field Hydrodynamic simulations of the magnetosphere of σ Ori E. We find that the X-ray emission from the star's magnetically confined wind shocks is very sensitive to the assumed mass-loss rate. To compare the simulations against the measured X-ray emission, we first disentangle the star from its recently discovered late-type companion using Chandra HRC-I observations. This then allows us to place an upper limit on the mass-loss rate of the primary, which we find to be significantly smaller than previously imagined.
Magnetic fields of massive stars
Authors: Hubrig Swetlana , Curé Michel , Ilyin Ilya , Schöller Markus
Published: July 2011

We recently carried out a spectropolarimetric study of a sample of massive O-type stars and pulsating β Cephei stars using the SOFIN echelle spectrograph at the 2.56 m Nordic Optical Telescope and the low-resolution FORS 2 spectrograph at the VLT in spectropolarimetric mode. The sample consists of massive stars already detected as magnetic in the course of our previous low-resolution polarimetric observations with FORS 1 and a few O-type stars with magnetic field detections reported in the literature.
Magnetic fluxes of massive stars: statistics and evolution
Authors: Kholtygin Alexander F. , Fabrika Sergei N. , Drake Natalia A. , Igoshev Andrei P.
Published: July 2011

The statistical properties of magnetic fields and magnetic fluxes of OB stars were investigated. The mean magnetic fluxes of massive OB stars appear to be 3 order larger than those for neutron stars.
Discovery of a strong magnetic field in the rapidly rotating B2Vn star HR 7355
Authors: Oksala Mary E. , Wade Gregg A. , Marcolino Wagner L. F. , Grunhut Jason H. , Bohlender David , Manset Nadine , Townsend Richard H. D. ,   the MiMeS Collaboration
Published: July 2011

We report on the detection of a strong, organized magnetic field in the helium-variable early B-type star HR 7355 using spectropolarimetric data obtained with ESPaDOnS on CFHT by the MiMeS large program. We also present results from new V-band differential photometry obtained with the CTIO 0.9m telescope. We investigate the longitudinal field, using a technique called Least-Squares Deconvolution (LSD), and the rotational period of HR 7355. These new observations strongly support the proposal that HR 7355 harbors a structured magnetosphere similar to that in the prototypical helium-strong star, σ Ori E.
Magnetism of the He-weak star HR 2949
Authors: Rivinius Thomas , Wade Gregg A. , Townsend Richard H. D. , Shultz Matthew , Grunhut Jason H. , Stahl Otmar ,   the MiMeS collaboration
Published: July 2011

A magnetic field and rotational line profile variability (lpv) is found in the He-weak star HR 2949. The field measured from metallic lines varies in a clearly non-sinusoidal way, and shows a phase lag relative to the morphologically similar He i equivalent width variations. The surface abundance patterns are strong and complex, and visible even in the hydrogen lines.
Of?p stars: a class of slowly rotating magnetic massive stars
Authors: Wade Gregg A. , Grunhut Jason H. , Marcolino Wagner L. F. , Martins Fabrice , Howarth Ian D. , Nazé Yael , Walborn Nolan R. ,   the MiMeS Collaboration
Published: July 2011

Only 5 Of?p stars have been identified in the Galaxy. Of these, 3 have been studied in detail, and within the past 5 years magnetic fields have been detected in each of them. The observed magnetic and spectral characteristics are indicative of organised magnetic fields, likely of fossil origin, confining their supersonic stellar winds into dense, structured magnetospheres. The systematic detection of magnetic fields in these stars strongly suggests that the Of?p stars represent a general class of magnetic O-type stars.
Populations of Be stars: stellar evolution of extreme stars
Authors: Martayan Christophe , Rivinius Thomas , Baade Dietrich , Hubert Anne-Marie , Zorec Jean
Published: July 2011

Among the emission-line stars, the classical Be stars known for their extreme properties are remarkable. The Be stars are B-type main sequence stars that have displayed at least once in their life emission lines in their spectrum. Beyond this phenomenological approach some progresses were made on the understanding of this class of stars. With high-technology techniques (interferometry, adaptive optics, multi-objects spectroscopy, spectropolarimetry, high-resolution photometry, etc) from different instruments and space mission such as the VLTI, CHARA, FLAMES, ESPADONS-NARVAL, COROT, MOST, SPITZER, etc, some discoveries were performed allowing to constrain the modeling of the Be stars stellar evolution but also their circumstellar decretion disks. In particular, the confrontation between theory and observations about the effects of the stellar formation and evolution on the main sequence, the metallicity, the magnetic fields, the stellar pulsations, the rotational velocity, and the binarity (including the X-rays binaries) on the Be phenomenon appearance is discussed. The disks observations and the efforts made on their modeling is mentioned. As the life of a star does not finish at the end of the main sequence, we also mention their stellar evolution post main sequence including the gamma-ray bursts. Finally, the different new results and remaining questions about the main physical properties of the Be stars are summarized and possible ways of investigations proposed. The recent and future facilities (XSHOOTER, ALMA, E-ELT, TMT, GMT, JWST, GAIA, etc) and their instruments that may help to improve the knowledge of Be stars are also briefly introduced.
Massive variable stars at very low metallicity?
Authors: Bomans Dominik J. , Weis Kerstin
Published: July 2011

Observational contraints on the evolution and instabilities of massive stars at very low metallicities are limited. Most of the information come from HST observations of one target, I Zw 18. Recent distance estimates of I Zw 18 put it at 17 Mpc, moving detailed studies of single stars clearly beyond the range of current ground based telescopes. Since massive stars with metallcities of 1/10 of solar and below are our best proxies for massive stars in (proto-) galaxies around the time of reionization, finding them and studying their evolution and instabilities is of premium importance for our understanding of galaxy formation, feedback, and the IGM reionization. Here we present pilot study results of variable stars in two more nearby extremely low metallicity galaxies, UGC 5340 and UGCA 292, and comment on the possibilities of more detailed studies of variable massive stars with new ground-based instrumentation.
Discussion – Populations of OB stars in galaxies
Authors: Wade Gregg A. , Saio Hideyuki
Published: July 2011

This article summarises the discussion following Session 3 (Populations of OB stars in galaxies) of IAUS 272.
Evolutionary study of the Be star 28 Tau
Authors: Ahmad Nazhatulshima , Zainuddin Mohd. Zambri , Yahya Mohd. Sahar , Eggleton Peter P. , Malasan Hakim L.
Published: July 2011

We present an evolutionary study of 28 Tau, a Be star, in connection with its rapid rotation. The photometric data during the absence of its envelope in 1921 have been used to determine the effective temperature and luminosity of the star at the main sequence of the HR diagram. From an evolutionary model, we found that the mass and radius of the star are about 3.2 M⊙ and 3.2 R⊙ respectively. The equatorial rotation velocity of the star, νe found to be close to its critical velocity, νcr where νe/νcr ≃ 0.87.
Are the stellar winds in IC 1613 stronger than expected?
Authors: Herrero Artemio , Garcia Maria , Uytterhoeven Katrien , Najarro Francisco , Lennon Daniel J. , Simón-Díaz Sergio , Castro Norberto , Puls Joachim , Vink Jorick S. , Urbaneja Miguel A. , de Koter Alex
Published: July 2011

In this poster we present the results of our analyses of three early massive stars in IC 1613, whose spectra have been observed with VIMOS and analyzed with CMFGEN and FASTWIND. One of the targets resulted a possible LBV and the other two are Of stars with unexpectedly strong winds. The Of stars seem to be strongly contaminated by CNO products. Our preliminary results may represent a challenge for the theory of stellar atmospheres, but they still have to be confirmed by the analysis of more objects and a more complete coverage of the parameter space.
Photometric and spectroscopic study of candidate Be stars in the Magellanic Clouds
Authors: KT Paul , Subramaniam Annapurni , Mathew Blesson , Mennickent Ronald E. , Sabogal Beatriz
Published: July 2011

Mennickent et al. (2002) presented a catalogue of 1056 Be star candidates in the Small Magellanic cloud (SMC) by studying light curve variation using OGLE II data base. They classified these Be star candidates of the SMC in four categories: Type 1 stars showing outbursts (139 stars); Type 2 stars showing sudden luminosity jumps (154 stars); Type 3 stars showing periodic or near periodic variations (78 stars); Type 4 stars showing light curves similar to Galactic Be stars (658 stars). They suggested that Type 4 could be Be stars. On the other hand, they suggested that Type-3 stars may not be linked to the Be star phenomenon at all.
The VLT-FLAMES Tarantula survey
Authors: Lennon Daniel J. , Evans Christopher J. , Bastian Nate , Beletsky Yuri , Brott Ines , Cantiello Matteo , Carraro Giovanni , Clark J. Simon , Crowther Paul A. , de Koter Alex , de Mink Selma E. , Dufton Philip L. , Dunstall Paul , Gieles Mark , Gräfener Goetz , Hénault-Brunet Vincent , Herrero Artemio , Howarth Ian D. , Langer Norbert , Apellániz Jesus Maíz , Markova Nevena , Najarro F. Paco , Puls Joachim , Sana Hugues , Simón-Díaz Sergio , Smartt Stephen J. , Stroud Vanessa E. , Taylor William D. , van Loon Jacco T. , Vink Jorick S. , Walborn Nolan R.
Published: July 2011

The Tarantula Survey is an ESO Large Programme which has obtained multi-epoch spectroscopy of over 1,000 massive stars in the 30 Doradus region of the Large Magellanic Cloud. The assembled consortium will exploit these data to address a range of fundamental questions in both stellar and cluster evolution.
Variability of young massive stars in the Arches cluster
Authors: Markakis Kostas , Bonanos Alceste Z. , Pietrzynski Grzegorz , Macri Lucas , Stanek Kris Z.
Published: July 2011

We present preliminary results of the first near-infrared variability study of the Arches cluster, using adaptive optics data from NIRI/Gemini and NACO/VLT. The goal is to discover eclipsing binaries in this young (2.5 ± 0.5 Myr), dense, massive cluster for which we will determine accurate fundamental parameters with subsequent spectroscopy. Given that the Arches cluster contains more than 200 Wolf-Rayet and O-type stars, it provides a rare opportunity to determine parameters for some of the most massive stars in the Galaxy.
IR mass loss rates of LMC and SMC O stars
Authors: Massa Derck L. , Fullerton Alex W. , Lennon Danny J. , Prinja Raman K.
Published: July 2011

We use a combination of VJHK and Spitzer [3.6], [5.8] and [8.0] photometry, to determine IR excesses in a sample of LMC and SMC O stars. This sample is ideal for determining excesses because: 1) the distances to the stars, and hence their luminosities, are well-determined, and; 2) the very small line of sight reddenings minimize the uncertainties introduced by extinction corrections. We find IR excesses much larger than expected from Vink et al. (2001) mass loss rates. This is in contrast to previous wind line analyses for many of the LMC stars which suggest mass loss rates much less than the Vink et al. predictions. Together, these results indicate that the winds of the LMC and SMC O stars are strongly structured (clumped).
The IACOB spectroscopic database of galactic OB stars
Authors: Simón-Díaz Sergio , Castro Norberto , Garcia Miriam , Herrero Artemio
Published: July 2011

We present the IACOB spectroscopic database, the largest homogeneous database of high-resolution, high signal-to-noise ratio spectra of Northern Galactic OB-type stars compiled up to date. The spectra were obtained with the FIES spectrograph attached to the Nordic Optical Telescope. We briefly summarize the main characeristics and present status of the IACOB, first scientific results, and some future plans for its extension and scientific exploitation.
Observations of circumstellar disks
Authors: Stee Philippe
Published: July 2011

In this review I will present recent results obtained between 2005, which was the last “Be-stars” meeting in Sapporo, and 2010, on the observations of circumstellar disks around active hot stars.
X-ray spectral diagnostics of activity in massive stars
Authors: Cohen David H. , Wollman Emma E. , Leutenegger Maurice A.
Published: July 2011

X-rays give direct evidence of instabilities, time-variable structure, and shock heating in the winds of O stars. The observed broad X-ray emission lines provide information about the kinematics of shock-heated wind plasma, enabling us to test wind-shock models. And their shapes provide information about wind absorption, and thus about the wind mass-loss rates. Mass-loss rates determined from X-ray line profiles are not sensitive to density-squared clumping effects, and indicate mass-loss rate reductions of factors of 3 to 6 over traditional diagnostics that suffer from density-squared effects. Broad-band X-ray spectral energy distributions also provide mass-loss rate information via soft X-ray absorption signatures. In some cases, the degree of wind absorption is so high, that the hardening of the X-ray SED can be quite significant. We discuss these results as applied to the early O stars ζ Pup (O4 If), 9 Sgr (O4 V((f))), and HD 93129A (O2 If*).
Activity of Herbig Be stars and their environment
Authors: Alecian Evelyne
Published: July 2011

The Herbig Ae/Be stars are the high-mass counterparts of the T Tauri stars, and are therefore considered as the pre-main sequence progenitors of the A/B stars. These stars are still contracting towards the main sequence, and are surrounded by dust and gas, remnants of their parental molecular cloud. In order to understand the formation processes at high mass, as well as the magnetic and rotation properties of the MS A/B stars, it is fundamental to understand the structure of the circumstellar matter of the Herbig Ae/Be stars, as well as the interaction of these PMS stars with their close environment. In this talk I will review our current knowledge about the properties of the circumstellar environment of the Herbig Ae/Be stars as well as the possible physical processes at the origin of their observed activities.
The circumstellar environment of the FS CMa star IRAS 00470+6429
Authors: Carciofi Alex C. , Miroshnichenko Anatoly S. , Bjorkman Jon E.
Published: July 2011

FS CMa type stars are a recently described group of objects with the B[e] phenomenon that exhibit strong emission-line spectra and strong IR excesses. In this paper we report the first attempt for a detailed modeling of IRAS 00470+6429, for which we have the best set of observations. Our modeling is based on two key assumptions: the star has a main-sequence luminosity for its spectral type (B2) and that the circumstellar (CS) envelope is bimodal, composed of a slowly outflowing disk-like wind and a fast polar wind. Both outflows are assumed to be purely radial. We adopt a novel approach to describe the dust formation site in the wind that employs timescale arguments for grain condensation and a self-consistent solution for the dust destruction surface. With the above assumptions we were able to reproduce satisfactorily many observational properties of IRAS 00470+6429, including the HI line profiles and the overall shape of the spectral energy distribution.
Disk-loss and disk-renewal phases in classical Be stars – II. Detailed analysis of spectropolarimetric data
Authors: Draper Zachary H. , Wisniewski John P. , Bjorkman Karen S. , Bjorkman Jon E. , Haubois Xavier , Carciofi Alex C. , Meade Marilyn R.
Published: July 2011

In Wisniewski et al. (2010), paper I, we analyzed 15 years of spectroscopic and spectropolarimetric data from the Ritter and Pine Bluff Observatories of 2 Be stars, 60 Cygni and π Aquarii, when a transition from Be to B star occurred. Here we analyze the intrinsic polarization, where we observe loop-like structures caused by the rise and fall of the polarization Balmer Jump and continuum V-band polarization being mismatched temporaly with polarimetric outbursts. We also see polarization angle deviations from the mean, reported in paper I, which may be indicative of warps in the disk, blobs injected at an inclined orbit, or spiral density waves. We show our ongoing efforts to model time dependent behavior of the disk to constrain the phenomena, using 3D Monte Carlo radiative transfer codes.
Investigating the continuum linear polarization of Be stars
Authors: Halonen Robbie J. , Mackay Frances E. , Jones Carol E. , Sigut T. A. Aaron
Published: July 2011

In order to understand the mechanisms that govern the development of circumstellar disks surrounding classical Be stars, we use computational codes to create theoretical models of these particular objects with their gaseous environments and we compare the predicted observables to astronomical observations. In this study, we present the use of the non-LTE radiative transfer code of Sigut & Jones (2007) to examine the effect of a self-consistent thermal structure and realistic chemical composition on the polarization of the classical Be star γ Cassiopeia. Primarily, we investigate the effect of several improvements on the pioneering work of Poeckert & Marlborough (1978) in calculating the polarization levels of γ Cas. We establish best-fit models for the same observations and analyze the implications of the differences between our results and those obtained by Poeckert & Marlborough.
Probing Be star disks: new insights from Hα spectroscopy and detailed numerical models
Authors: Jones Carol E. , Tycner Christopher , Silaj Jessie , Smith Ashly , Sigut T. A. Aaron
Published: July 2011

Hα high resolution spectroscopy combined with detailed numerical models is used to probe the physical conditions, such as density, temperature, and velocity of Be star disks. Models have been constructed for Be stars over a range in spectral types and inclination angles. We find that a variety of line shapes can be obtained by keeping the inclination fixed and changing density alone. This is due to the fact that our models account for disk temperature distributions self-consistently from the requirement of radiative equilibrium. A new analytical tool, called the variability ratio, was developed to identify emission-line stars at particular stages of variability. It is used in this work to quantify changes in the Hα equivalent widths for our observed spectra.
Hydrodynamical simulations of Pinwheel nebula WR 104
Authors: Lamberts Astrid , Fromang Sebastien , Dubus Guillaume
Published: July 2011

Pinwheel Nebulae are colliding wind binaries (CWB) composed of a Wolf-Rayet star and an early-type star. We first compare our simulations to analytic solutions for CWB. Then we perform large scale 2D simulations of the particular system WR 104. We determine the properties of the gas in the winds and confirm the flow in the spiral has a ballistic motion.
Spectrally and spatially resolved Hα emission from Be stars: their disks rotate Keplerian
Authors: Oudmaijer René D. , Wheelwright Hugh E. , Carciofi Alex C. , Bjorkman Jon E. , Bjorkman Karen S.
Published: July 2011

We test whether Be star disks rotate in a Keplerian or an Angular Momentum Conserving fashion. This is done by employing sub-milli arcsecond spectroastrometry around Hα. We spatially resolve the disks, and are the first to do so at such a high spectral resolution. We fit the emission line profiles with parametric models. The Keplerian models reproduce the spectro-astrometry, whereas the AMC models do not, thereby supporting the viscous disk model for Be stars.
Multi-epoch interferometric observations of the Be star ζ Tau
Authors: Schaefer Gail H. , Gies Douglas R. , Monnier John D. , Richardson Noel D. , Touhami Yamina N. , Zhao Ming
Published: July 2011

We present interferometric observations of the Be star ζ Tau obtained using the MIRC beam combiner at the CHARA Array during four epochs in 2007–2009. Fitting a geometric model to the data reveals a nearly edge-on disk with a FWHM of ~1.8 milli-arcsec in the H-band. The non-zero closure phases indicate an asymmetry in the brightness distribution. Interestingly, when combining our results with previously published interferometric observations of ζ Tau, we find a correlation between the position angle of the disk and the spectroscopic V/R ratio, suggesting that the tilt of the disk might be precessing. This work is part of a multi-year monitoring campaign to investigate the development and outward motion of asymmetric structures in the disks of Be stars.