2,515 research outputs found
OH-selected AGB and post-AGB stellar objects II.Blue versus red evolution off the AGB
Using objects found in a systematic survey of the galactic Plane in the
1612-MHz OH line, we discuss in detail two ``sequences'' of post-AGB evolution,
a red and a blue. We argue that the red and the blue groups separate by initial
mass at 4Msun, based on evolutionary-sequence turn-off colours, spectral energy
distributions, outflow velocities and scaleheight. The higher-mass (blue)
objects may have earlier AGB termination. The lower-mass (red) objects undergo
very sudden reddening for IRAS colour R21\sim1.2; these sources must all
undergo a very similar process at AGB termination. The transition colour
corresponds to average initial masses of 1.7Msun. A combined IRAS-MSX colour
proves a very sensitive tool to distinguish lower-mass, early post-AGB objects
from sources still on the AGB and also to distinguish more evolved post-AGB
objects from star-forming regions. The high-mass blue objects are the likely
precursors of bipolar planetary nebulae, whereas the low-mass red objects will
evolve into elliptical planetary nebulae.Comment: 12 pages, LaTex, 7 figures (1 colour), AJ (accepted
OH-selected AGB and post-AGB objects I.Infrared and maser properties
Using 766 compact objects from a survey of the galactic Plane in the 1612-MHz
OH line, new light is cast on the infrared properties of evolved stars on the
TP-AGB and beyond. The usual mid-infrared selection criteria, based on IRAS
colours, largely fail to distinguish early post-AGB stages. A two-colour
diagram from narrower-band MSX flux densities, with bimodal distributions,
provides a better tool to do the latter. Four mutually consistent selection
criteria for OH-masing red PPNe are given, as well as two for early post-AGB
masers and one for all post--AGB masers, including the earliest ones. All these
criteria miss a group of blue, high-outflow post-AGB sources with 60-mum
excess; these will be discussed in detail in Paper II. The majority of post-AGB
sources show regular double-peaked spectra in the OH 1612-MHz line, with fairly
low outflow velocities, although the fractions of single peaks and irregular
spectra may vary with age and mass. The OH flux density shows a fairly regular
relation with the stellar flux and the envelope optical depth, with the maser
efficiency increasing with IRAS colour R21. The OH flux density is linearly
correlated with the 60-mum flux density.Comment: 16 pages, LaTex, 22 figures, AJ (accepted
Rapportage Evaluatie Projecten VWS-Impulsmiddelen Den Haag: Pilots Actieprogramma Dak- en Thuisloze Jongeren Daklozenpunt Zoetermeer:Rapportage, 27 januari 2022
Rapportage Evaluatie Projecten VWS-Impulsmiddelen Den Haag: Pilots Actieprogramma Dak- en Thuisloze Jongeren Daklozenpunt Zoetermeer:Rapportage, 27 januari 2022
External validation of a dynamic prediction model for repeated predictions of natural conception over time
This work was supported by a Chief Scientist Office postdoctoral training fellowship in health services research and health of the public research (ref PDF/12/06). There are no conflicts of interest.Peer reviewedPostprin
Rapportage Voorkomen Herhaalde Dakloosheid Utrecht:Rapportage derde meting van vijfjarig onderzoek naar recidive dakloosheid in Utrecht, meting 2021
Rapportage Voorkomen Herhaalde Dakloosheid Utrecht:Rapportage derde meting van vijfjarig onderzoek naar recidive dakloosheid in Utrecht, meting 2021
Surface defreezing of glasses
A glass surface may still flow below the bulk glass transition temperature,
where the underlying bulk is frozen. Assuming the existence at T=T* of a bulk
thermodynamical glass transition, we show that the glass-vapor interface is
generally wetted by a liquid layer of thickness ~ -ln(T*-T) when T--> T*.
Contrary to standard surface melting of crystals however, the integrated value
of the diffusivity across the interface remains finite for T-->T*. Difference
in shape induced by bulk and by surface flow is discussed as a possible means
of experimental detection of surface defreezing.Comment: five pages, three figure
IVF for unexplained subfertility : whom should we treat?
Acknowledgements The authors would like to thank Tenovus Scotland and the Amsterdam Reproduction & Development Research Group for funding this project. We acknowledge the data management support of the Grampian Data Safe Haven (DaSH) and the associated financial support of NHS Research Scotland, through NHS Grampian investment in the Grampian DaSH. For more information, visit the DaSH website http://www.abdn.ac.uk/iahs/facilities/grampian-data-safe-haven.php. Funding Tenovus Scotland [grant G17.04], travel was supported by the Amsterdam Reproduction & Development Research Group [grant V.000296 to RvE].Peer reviewedPostprin
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