7,008 research outputs found
Large Misalignment between Stellar Bar and Dust Pattern in NGC 3488 Revealed by Spitzer and SDSS
A large position angle misalignment between the stellar bar and the
distribution of dust in the late-type barred spiral NGC 3488 was discovered,
using mid-infrared images from the Spitzer Space Telescope and optical images
from the Sloan Digital Sky Survey (SDSS). The angle between the bar and dust
patterns was measured to be 25+-2deg, larger than most of the misalignments
found previously in barred systems based on Ha or HI/CO observations. The
stellar bar is bright at optical and 3.6um, while the dust pattern is more
prominent in the 8um band but also shows up in the SDSS u and g-band images,
suggesting a rich interstellar medium environment harboring ongoing star
formation. This angular misalignment is unlikely to have been caused by
spontaneous bar formation. We suggest that the stellar bar and the dust pattern
may have different formation histories, and that the large misalignment was
triggered by a tidal interaction with a small companion. A statistical analysis
of a large sample of nearby galaxies with archival Spitzer data indicates that
bar structure such as that seen in NGC 3488 is quite rare in the local
Universe.Comment: 18 pages, 4 figures, 1 table, accepted for publication in New
Astronom
Manual small incision combined with negative power intraocular lens implantation for cataract with high myopia clinical observation
AIM: To evaluate the clinical effect of manual small incision combined with negative power intraocular lens implantation for cataract with high myopia. <p>METHODS: Totally 75 cases(98 eyes)with super high myopia and cataract which had underwent small incision combined with negative power intraocular lens implantation were studied retrospectively. Preoperative axial length and postoperative visual acuity, refractive diopter and expected deviation value(refractive deviation)were recorded. Eye conditions operation complications and postoperative were observed. The patients were followed-up for 6 to 12 months. <p>RESULTS: The mean preoperative axial length was 32.05±1.78mm. Best corrected visual acuity≥0.2 was in 66 eyes, accounting for 67.3%; ≥0.5 in 43 eyes, accounting for 43.9%; the postoperative refractive error <±1.00D was total 48 eyes, accounting for 49.0%; <±2.00D total 78 eyes, accounting for 79.6%. Intra-operative posterior capsular rupture occurred in 3 eyes. Intra-operative posterior elastic layer detachment occurred in 1 cases. The postoperative corneal edema was found in 21 eyes. Postoperative 6 months, posterior capsular opacification was found in 13 eyes, and the visual acuity recovered after Nd:YAG laser cut. No retinal detachment, secondary glaucoma, macular cystoid edema, intraocular lens shift and other complications were found. Two eyes had the symptom of binocular interference post-operation. Three months later, another eye was performed intraocular lens implantation. The symptoms were eliminated post-operation. <p>CONCLUSION: The manual small incision cataract extraction combined with negative power intraocular lens implantation for cataract with high myopia is safe, effective method
Aquabis(2-methyl-4-oxopyrido[1,2-a]pyrimidin-9-olato)zinc(II) monohydrate
The crystal structure of the title compound, [Zn(C9H7N2O2)2(H2O)]·H2O, involves discrete mononuclear complex molecules. The special positions on the rotation twofold axis are occupied by ZnII and O atoms of the coordinated and uncoordinated water molecules. The coordination around the ZnII atom can be described as transitional from trigonal-bipyramidal to square-pyramidal. The two chelating 2-methyl-4-oxopyrido[1,2-a]pyrimidin-9-olate ligands and the coordinated water molecule form the Zn coordination. O—H⋯O hydrogen bonds between the coordinated water molecule and the ligand and between the uncoordinated water molecule and the ligand dominate the crystal packing
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