143 research outputs found
Velocity Dispersion of Dissolving OB Associations Affected by External Pressure of Formation Environment
This paper presents a possible way to understand dissolution of OB
associations (or groups). Assuming rapid escape of parental cloud gas from
associations, we show that the shadow of the formation environment for
associations can be partially imprinted on the velocity dispersion at their
dissolution. This conclusion is not surprising as long as associations are
formed in a multiphase interstellar medium, because the external pressure
should suppress expansion caused by the internal motion of the parental clouds.
Our model predicts a few km s as the internal velocity dispersion.
Observationally, the internal velocity dispersion is km s which
is smaller than our prediction. This suggests that the dissipation of internal
energy happens before the formation of OB associations.Comment: 6 pages. AJ accepte
The Night is Still Young:A Cross-Disciplinary Forum on Queer Nightlife Studies
Since 2020, a wave of academic and trade books has brought unprecedented attention to queer nightlife. Whereas this special issue of TSQ advances queer nightlife as a site for continued study in sociology, this forum opens a conversation between ten leading scholars who have often carried out their work in distinct social science and humanities fields, including sociology, geography, ethnomusicology, performance studies, religion, and media studies. In a spirit of academic generosity, they become interlocutors who exchange stories, analytical frameworks, and investments with the goal that they might learn from each other; they bond over shared nightlife and research experiences, including ethnographic methods and attention to affect. This forum poses questions and insights that will enrich how future scholarship can build toward more rigorous, capacious, and imaginative queer methods – within and beyond sociology
Lipid dynamics in diisobutylene-maleic acid (Dibma) lipid particles in presence of sensory rhodopsin ii
Amphiphilic diisobutylene/maleic acid (DIBMA) copolymers extract lipid-encased membrane proteins from lipid bilayers in a detergent-free manner, yielding nanosized, discoidal DIBMA lipid particles (DIBMALPs). Depending on the DIBMA/lipid ratio, the size of DIBMALPs can be broadly varied which makes them suitable for the incorporation of proteins of different sizes. Here, we examine the influence of the DIBMALP sizes and the presence of protein on the dynamics of encased lipids. As shown by a set of biophysical methods, the stability of DIBMALPs remains unaffected at different DIBMA/lipid ratios. Coarse-grained molecular dynamics simulations confirm the formation of viable DIBMALPs with an overall size of up to 35 nm. Electron paramagnetic resonance spectroscopy of nitroxides located at the 5th, 12th or 16th carbon atom positions in phosphatidylcholine-based spin labels reveals that the dynamics of enclosed lipids are not altered by the DIBMALP size. The presence of the membrane protein sensory rhodopsin II from Natronomonas pharaonis (NpSRII) results in a slight increase in the lipid dynamics compared to empty DIBMALPs. The light-induced photocycle shows full functionality of DIBMALPs-embedded NpSRII and a significant effect of the protein-to-lipid ratio during preparation on the NpSRII dynamics. This study indicates a possible expansion of the applicability of the DIBMALP technology on studies of membrane protein–protein interaction and oligomerization in a constraining environment
Low-ionization structures in planetary nebulae: confronting models with observations
Around 50 PNe are presently known to possess "small-scale" low-ionization
structures (LISs). We consider here jets, jet-like, symmetrical and
non-symmetrical LISs and present a detailed comparison of the existing model
predictions with the observational morphological and kinematical properties. We
find that nebulae with LISs appear indistinctly spread among all morphological
classes of PNe, indicating that the processes leading to the formation of LISs
are not necessarily related to those responsible for the asphericity of the
large-scale morphological components of PNe. We show that both the observed
velocities and locations of most non-symmetrical LISs can be reasonably well
reproduced assuming either fossil condensations originated in the AGB wind or
in-situ instabilities. The jet models proposed to date (HD and MHD interacting
winds or accretion-disk collimated winds) appear unable to account
simultaneously for the kinematical ages and the angle between the jet and the
symmetry axes of the nebulae. The linear increase in velocity observed in
several jets favors MHD confinement compared to pure HD interacting wind
models. On the other hand, we find that the formation of jet-like systems
characterized by relatively low expansion velocities cannot be explained by any
of the existing models. Finally, the knots which appear in symmetrical and
opposite pairs of low velocity could be understood as the survival of fossil
(symmetrical) condensations formed during the AGB phase or as structures that
have experienced substantial slowing down by the ambient medium.Comment: 21 pages including 5 tables. To appear in ApJ 547, Jan 2001. Also
available at http://www.iac.es/publicaciones/preprints.htm
German evidence and consensus‐based (S3) guideline: Vaccination recommendations for the prevention of HPV‐associated lesions
Anogenital and oropharyngeal infections with human papilloma viruses (HPV) are common. Clinically manifest disease may significantly impact quality of life; the treatment of HPV-associated lesions is associated with a high rate of recurrence and invasive neoplasms, such as cervical, anal, vulvar, penile, and oropharyngeal cancers, which are characterized by significant morbidity and mortality. Vaccination against HPV is an effective and safe measure for the primary prevention of HPV-associated lesions, but immunization rates are still low in Germany. The present publication is an abridged version of the German evidence and consensus-based guideline "Vaccination recommendations for the prevention of HPV-associated lesions", which is available on the website of the German Association of the Scientific Medical Societies (AWMF). On the basis of a systematic review with meta-analyses, a representative panel developed and agreed upon recommendations for the vaccination of different populations against HPV. In addition, consensus-based recommendations were developed for specific issues relevant to everyday practice. Based on current evidence and a representative expert consensus, these recommendations are intended to provide guidance in a field in which there is often uncertainty and in which both patients and health care providers are sometimes confronted with controversial and emotionally charged points of view
ETHOS 1: a high-latitude planetary nebula with jets forged by a post-common-envelope binary central star
The definitive version can be found at: http://onlinelibrary.wiley.com/ Copyright Royal Astronomical SocietyWe report on the discovery of ETHOS 1 (PN G068.1+11.0), the first spectroscopically confirmed planetary nebula (PN) from a survey of the SuperCOSMOS Science Archive for high-latitude PNe. ETHOS 1 stands out as one of the few PNe to have both polar outflows (jets) travelling at 120 +/- 10 km s-1 and a close binary central star. The light curve observed with the Mercator Telescope reveals an orbital period of 0.535 d and an extremely large amplitude (0.816 mag) due to irradiation of the companion by a very hot pre-white dwarf. ETHOS 1 further strengthens the long-suspected link between binary central stars of PNe (CSPN) and jets. The Isaac Newton Telescope/Intermediate Dispersion Spectrograph and Very Large Telescope (VLT) FORS spectroscopy of the CSPN reveals weak N iii, C iii and C iv emission lines seen in other close binary CSPN and suggests that many CSPN with these weak emission lines are misclassified close binaries. We present VLT FORS imaging and Manchester Echelle Spectrometer long-slit observations from which a kinematic model of the nebula is built. An unusual combination of bipolar outflows and a spherical nebula conspires to produce an X-shaped appearance. The kinematic age of the jets (1750 +/- 250 yr kpc-1) is found to be more than that of the inner nebula (900 +/- 100 yr kpc-1), consistent with previous studies of similar PNe. Emission-line ratios of the jets are found to be consistent with that of reverse-shock models for fast low-ionization emitting regions (FLIERs) in PNe. Further large-scale surveys for close binary CSPN will be required to securely establish whether FLIERs are launched by close binaries.Peer reviewe
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