The curious case of offset bars : markers for a baby galaxy disk or signposts of an interaction with dark matter sub halos?

>Magister Scientiae - MScWe have used the Spitzer Survey of Stellar Structure in Galaxies (S⁴G) as a representative sample of the local universe (total of 2352 galaxies in S⁴G) to make a catalog of offset disk barred galaxies. Using the combined variation of the position angle and the ellipticity (provided by ellipse fit) and also through visual inspection, we have been able to identify all offset structures in S⁴G. While primary bars are present in 2=3 of the disk galaxies in the visible universe, offset bars have a much lower fraction. Of the ̴ 1500 (3.6µm images) disk galaxies available in S⁴G, we classified only 49 as offset barred disk galaxies. We have determined basic properties (bar to total luminosity ratio, bar length, disk scale-length and bars of offset bars shape) using GALFIT, a widely used galaxy decomposition software package. Our main conclusion is that all the offset bars are boxy, independent of their offset from the galaxy center, or the mass of the host galaxy. Additionally we find that, the early type offset bars seem to be more boxy than the late types. The comparison of our offset sample with two other samples, respectively, low mass and high mass normal barred galaxies ("normal" for bars located at the photometric center of the host galaxy), reveals them to be at an intermediate position between the two normal samples. The bar length, disk scale-length and bar to total luminosity ratio are on average larger than the low mass normal and smaller than high mass normal barred galaxies. We have found, overall, a tighter correlation between the disk and bar properties for offset bars in comparison to the two normal samples. Our explanation is that, although the offset has no visible impact on the global shape of the bars, the process responsible for these disturbances seems to affect the star formation rate such that their disk and bars are on average more active than the normal barred galaxies in the same mass range, but not enough to surpass normal barred galaxies with much higher mass

Vegetation areas for which the trend of NDVI in summer for 1982–2006 is significant at the 0.05 level and their trend slope.

<p>Vegetation areas for which the trend of NDVI in summer for 1982–2006 is significant at the 0.05 level and their trend slope.</p

Average growing season NDVI for 1982–2006.

<p>Average growing season NDVI for 1982–2006.</p

Average annual precipitation for different periods at three meteorological stations (unit: mm).

<p>Average annual precipitation for different periods at three meteorological stations (unit: mm).</p

Topography and river system of the Heihe River Basin.

<p>Topography and river system of the Heihe River Basin.</p

Vegetation areas for which the trend of NDVI in spring for 1982–2006 is significant at the 0.05 level and their trend slope.

<p>Vegetation areas for which the trend of NDVI in spring for 1982–2006 is significant at the 0.05 level and their trend slope.</p

Annual river flows at the Yingluo Gorge and Zhengyi Gorge for 1981–2006 and their trend lines.

<p>Annual river flows at the Yingluo Gorge and Zhengyi Gorge for 1981–2006 and their trend lines.</p

Land cover in the Heihe River Basin.

<p>Land cover in the Heihe River Basin.</p

Data_Sheet_1_Dietary spirulina supplementation modifies rumen development, fermentation and bacteria composition in Hu sheep when consuming high-fat dietary.docx

IntroductionThis study aims to investigate the long-term effects of spirulina supplementation in a high-fat diet (HFD) on rumen morphology, rumen fermentation, and the composition of rumen microbiota in lambs. Spirulina is a blue-green microalgae that has been shown to have high nutritional value for livestock.MethodsFifty-four lambs were randomly divided into three groups: a normal chow diet (NCD) group, a high-fat diet (HFD) group, and a high-fat diet supplemented with 3% spirulina (HFD+S) group. Rumen morphology, rumen fermentation, and rumen microbiota were analyzed at the end of the study.ResultsSpirulina supplementation improved the concentration of volatile fatty acids and rumen papilla length. Additionally, there was a tendency for an increase in rumen weight and an upregulation of the genes Claudin-1, Claudin-4, and Occludin in the HFD+S group. Pyrosequencing of the 16S ribosomal RNA gene also showed that spirulina supplementation significantly changed the rumen microbiota composition in the HFD group, with a decrease in richness and diversity. Specifically, the relative abundance of Prevotella 9 and Megasphaera was significantly increased in the HFD group compared to the NCD group, while spirulina supplementation reversed these changes.DiscussionThis study suggests that 3% spirulina supplementation can improve rumen development and fermentation, and effectively relieve rumen microbe disorders in lambs caused by a high-fat diet. However, further research is needed to confirm the findings and to examine the long-term effects of spirulina supplementation in different types of livestock and under different dietary conditions.</p