Rotational velocities of A-type stars I. Measurement of vsini in the southern hemisphere

Within the scope of a Key Programme determining fundamental parameters of stars observed by HIPPARCOS, spectra of 525 B8 to F2-type stars brighter than V=8 have been collected at ESO. Fourier transforms of several line profiles in the range 4200-4500 A are used to derive vsini from the frequency of the first zero. Statistical analysis of the sample indicates that measurement error is a function of vsini and this relative error of the rotational velocity is found to be about 6% on average. The results obtained are compared with data from the literature. There is a systematic shift from standard values from Slettebak et al. (1975), which are 10 to 12% lower than our findings. Comparisons with other independent vsini values tend to prove that those from Slettebak et al. are underestimated. This effect is attributed to the presence of binaries in the standard sample of Slettebak et al., and to the model atmosphere they used.Comment: 17 pages, includes 18 figures, accepted in A&

Continued ultraviolet studies of some Be stars of later type

Anomalous ionization (C IV and Si IV) is seen in IUE spectra of Be stars as late as B8, and occurs also in standard stars of similar spectral type. Asymmetrical lines suggesting mass loss are present in all the Be stars and several of the standard stars as well, with no obvious correlation with v sin i. Emission shoulders are present in the Mg II lines of two B5e stars but not in Be stars of later type. Again there is no correlation with v sin i. The A-F shell stars show rich Fe II absorption spectra in the ultraviolet, in one case with velocity structure

Be-star rotation: how close to critical?

We argue that, in general, observational studies of Be-star rotation have paid insufficient attention to the effects of equatorial gravity darkening. We present new line-profile calculations that emphasize the insensitivity of line width to rotation for fast rotators. Coupled with a critical review of observational procedures, these calculations suggest that the observational parameter v sin(i) may systematically underestimate the true projected equatorial rotation velocity, ve sin(i), by some tens of per cent for rapid rotators. The crucial implication of this work is that Be stars may be rotating much closer to their critical velocities than is generally supposed, bringing a range of new processes into contention for the elusive physical mechanism responsible for the circumstellar disk thought to be central to the Be phenomenon.Comment: 8 pages, 3 figures, shortened Sec. 6.3, new Sec. 6.4. Accepted by MNRA

La variable de helio HD 125823

In part I the behavior of the spectrum between 1908 and 1986 is analysed. The spectral type varied between B2 V and B7 III. This object represents very probably a new type of variables. In part II it is shown, on the basis of 110 Å/mm spectrograms taken at La Plata, that the star varies in spectral type with a period of 8ᵈ8061. Possible mechanisms which might account for this variation are examined. The work reported here has meanwhile appeared in press in the Astrophysical Journal Letters (1968) and Nature 219, 1137 (1968).Asociación Argentina de Astronomí

La variable de helio HD 125823

In part I the behavior of the spectrum between 1908 and 1986 is analysed. The spectral type varied between B2 V and B7 III. This object represents very probably a new type of variables. In part II it is shown, on the basis of 110 Å/mm spectrograms taken at La Plata, that the star varies in spectral type with a period of 8ᵈ8061. Possible mechanisms which might account for this variation are examined. The work reported here has meanwhile appeared in press in the Astrophysical Journal Letters (1968) and Nature 219, 1137 (1968).Asociación Argentina de Astronomí

Risiko for cervical intraepitelial neoplasi grad 2 eller høyere blant kvinner med ASC-US/LSIL og HPV-mRNA-negativ triage – en registerbasert kohortstudie.

Bakgrunn Det er omdiskutert hvordan man skal følge opp kvinner med lavgradige celleforandringer i screeningprogrammet for livmorhalskreft. I perioden 1. juli 2005 til 30. juni 2014 ble det utført sekundærscreening (forsinket triage) med HPV-test og ny celleprøve 6-12 måneder etter primærscreening som viser ASC-US/LSIL/uegnet. Vi har gjort en historisk prospektiv kohortstudie innenfor det norske screeningprogrammet for livmorhalskreft der vi sammenligner etterlevelse av anbefalinger for oppfølgning og forekomst av CIN2+ i en gruppe med gjentatt ASC-US/LSIL og negativ HPV-test ved triage med en gruppe som har normal celleprøve. Materiale og metode Vi har estimert risiko for CIN2+ og CIN3+ blant 1 063 kvinner med ASC- US/LSIL/normal/uegnet celleprøve og negativ HPV-test ved triage, og 25 948 kvinner med normal celleprøve ved 36, 42 og 78 måneder blant kvinner hjemmehørende i Troms og Finnmark. All prøvehistorikk på kvinnene er hentet fra databasen SymPathy som mottar og analyserer alle cytologiske og histologiske prøver for Troms og Finnmark. Resultater Det var signifikant forskjell på eksponert og ikke-eksponert gruppe med tanke på forekomst av CIN2+ og CIN3+ både ved 36, 42 og 78 måneder. Hazard Ratio for CIN2+ og CIN3+ var henholdsvis 14,1 (95% CI 8,7- 22,8) og 9,7 (95% CI 4,5 - 20,8) for eksponerte sammenlignet med ikke-eksponerte kvinner. Ved 36 måneder var den kumulative risikoen for CIN2+ henholdsvis 2,6% (95% CI: 1,5-3,8) og 0,3% (95% CI: 0,2-0,3), mens kumulativ risiko for CIN3+ var 0,9% (95% CI: 0,2-1,5) og 0,2% (95% CI: 0,1-0,2). Signifikant flere eksponerte kvinner (47%) tar ny cytologisk prøve for tidlig (innen 2 år) sammenlignet med kontroll kohorten (17%). Konklusjon Kvinner med ASC-US/LSIL ved primærscreening og ASC-US/LSIL/normal/uegnet celleprøve i kombinasjon med negativ HPV-test har signifikant høyere risiko for CIN2+ og CIN3+ enn kvinner med normal celleprøve, men den kumulative insidensen av CIN3+ blant eksponerte er lav nok til at retur til screening hvert 3. år er tilrådelig

Understanding of order in participatory housing interventions

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1987.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.Includes bibliographical references (leaves 60-62).This paper argues that the professional involved with participatory housing interventions needs a new way to practice. The improvement of housing demands a constructive dialogue in a working context that defies rigid ways of solving problems. Meaningful contribution hinges on the professionals abilities to communicate in this unpredictable environment. The clear explanation of ideas and a willingness to develop them with others, requires a new understanding on which to base professional actions. The argument is built on two issues. A discussion of different ways to get things done explores the issue of order. Procedures and methods order decisions when goals are fixed and interests are easily managed. If these control s are not possible, an approach offers flexibility not found in more regular ways of ordering. The context that requires an approach is the second issue. This is the middle ground, where decisions are ordered by the participation of those involved. Change is assembled piecemeal, as participants meet, discuss and make informed decisions. Order and context are developed in the argument that follows. Housing is presented as a complex subject that avoids simple definition. It changes naturally over time; a characteristic that reflects the needs of users, but has proven a nemesis for those intervening. A brief history of intervention evaluates the housing order that has resulted. It is concluded that natural change requires those affected to also take part in making decisions. This participation means the sharing of control, a condition outside of the present norm. For housing interventions to be participatory, a new context must be recognised - the middle ground. The last section speculates on professional practice on the middle ground. In addition to traditional expertise, the professional must learn to support change. Interactions with a variety of participants require new skills that explain ideas legibly, and then facilitate their development with others. It is proposed that this new understanding is needed in participatory housing interventions.by John Andrew Slettebak.M.Arch

A representative sample of Be stars IV: Infrared Photometry and the Continuum Excess

We present infra-red (JHK) photometry of 52 isolated Be stars of spectral types O9--B9 and luminosity classes III--V. We describe a new method of reduction, enabling separation of interstellar reddening and circumstellar excess. Using this technique we find that the disc emission makes a maximum contribution to the optical (B-V) colour of a few tenths of a magnitude. We find strong correlations between a range of emission lines (H\alpha, Br\gamma, Br11, and Br18) from the Be stars' discs, and the circumstellar continuum excesses. We also find that stellar rotation and disc excess are correlated.Comment: 10 pages, 9 figures, accepted for publication in Astronomy and Astrophysics. Other papers in this series can be obtained at http://cwis.livjm.ac.uk/astro/research/environs.htm

Abundance analysis of Am binaries and search for tidally driven abundance anomalies - III. HD116657, HD138213, HD155375, HD159560, HD196544 and HD204188

We continue here the systematic abundance analysis of a sample of Am binaries in order to search for possible abundance anomalies driven by tidal interaction in these binary systems. New CCD observations in two spectral regions (6400-6500, 6660-6760 AA) of HD116657, HD138213, HD155375, HD159560, HD196544 and HD204188 were obtained. Synthetic spectrum analysis was carried out and basic stellar properties, effective temperatures, gravities, projected rotational velocities, masses, ages and abundances of several elements were determined. We conclude that all six stars are Am stars. These stars were put into the context of other Am binaries with 10 < Porb < 200 days and their abundance anomalies discussed in the context of possible tidal effects. There is clear anti-correlation of the Am peculiarities with v sin i. However, there seems to be also a correlation with the eccentricity and may be with the orbital period. The dependence on the temperature, age, mass, and microturbulence was studied as well. The projected rotational velocities obtained by us were compared to those of Royer et al. (2002) and Abt & Morrell (1995).Comment: 11 pages, 3 tables, 12 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Societ