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1
Spectropolarimetry of Galactic stars with anomalous extinction sightlines

Cikota, Aleksandar,Hoang, Thiem,Taubenberger, Stefan,Patat, Ferdinando,Mazzei, Paola,Cox, Nick L.J.,Zelaya, Paula,Cikota, Stefan,Tomasella, Lina,Benetti, Stefano,Rodeghiero, Gabriele Springer-Verlag 2018 Astronomy and astrophysics Vol.615 No.-
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Highly reddened type Ia supernovae (SNe Ia) with low total-to-selective visual extinction ratio values, RV, also show peculiar linear polarization wavelength dependencies with peak polarizations at short wavelengths (λmax ≲ 0.4 μm). It is not clear why sightlines to SNe Ia display such different continuum polarization profiles from interstellar sightlines in the Milky Way with similar RV values. We investigate polarization profiles of a sample of Galactic stars with low RV values, along anomalous extinction sightlines, with the aim to find similarities to the polarization profiles that we observe in SN Ia sightlines. We undertook spectropolarimetry of 14 stars, used archival data for 3 additional stars, and ran dust extinction and polarization simulations (by adopting the picket-fence alignment model) to infer a simple dust model (size distribution, alignment) that can reproduce the observed extinction and polarization curves. Our sample of Galactic stars with low RV values and anomalous extinction sightlines displays normal polarization profiles with an average λmax ~ 0.53 μm, and is consistent within 3σ to a larger coherent sample of Galactic stars from the literature. Despite the low RV values of dust toward the stars in our sample, the polarization curves do not show any similarity to the continuum polarization curves observed toward SNe Ia with low RV values. There is a correlation between the best-fit Serkowski parameters K and λmax, but we did not find any significant correlation between RV and λmax. Our simulations show that the K-λmax relationship is an intrinsic property of polarization. Furthermore, we have shown that in order to reproduce polarization curves with normal λmax and low RV values, a population of large (a ≥ 0.1μm) interstellar silicate grains must be contained in the dust composition.
2
Clinical and anatomical importance of foramen magnum and craniocervical junction structures in the perspective of surgical approaches

Berin Tuğtağ Demir,Simge Eşme,Dilara Patat,Burak Bilecenoğlu 대한해부학회 2023 Anatomy & Cell Biology Vol.56 No.3
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This study was conducted to investigate the clinical and anatomical importance of the relevant region from theperspective of surgical approaches by determining the morphometric analysis of the craniocervical junction and foramen magnum (FM) region and determining their distances from important anatomical points. This research was carried out with 59 skulls found at the Anatomy Laboratories of Erciyes and Ankara Medipol University. Metric measurements of FM and condyle, FM shape, condyle-fossa relationship, and pharyngeal tubercle (PT) were made in mm-based dry bone samples of unknown age and sex. The distance between the anterior notches and the FM was 87.01±4.35, the distance between the anterior notches and the PT was 77.70±4.24, the distance between the PT-sphenooccipital junction was 13.23±2.42, and the FM index was 81.86±7.47. The anteroposterior and transverse lengths of FM were determined as 33.80±2.99 and 27.72±2.30, respectively. The morphometric and morphological data available regarding the craniocervical junction showed significant differences between populations. Comprehensive knowledge of this topic will provide a better approach to treat Arnold Chiari Malformation, FM meningiomas, and other posterior cranial fossa lesions. Therefore, we believe that FM and craniocervical junction morphology will be a guide not only for anatomists, but also for radiologists, neurosurgeons, ENT surgeons, and orthopedists.