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Is GBT 1355+5439 a dark galaxy?
Get PDFWe present Hi imaging of GBT 1355+5439 performed with the Westerbork Synthesis Radio Telescope. This is a dark Hi object
recently discovered close to the nearby galaxy M101. We find GBT 1355+5439 to be an Hi cloud 5 × 3 arcmin in size. The total Hi
image and the kinematics show that the cloud consists of condensations that have small (∼10 km s−1) motions with respect to each
other. The column densities of the Hi are low; the observed peak value is 7.1 × 1019 cm−2. The velocity field shows a mild velocity
gradient over the body of GBT 1355+5439, possibly due to rotation, but it may also indicate large-scale radial motions. Although our
data are limited in sensitivity, at all positions the Hi velocity dispersion is higher than 5 km s−1 and no narrow, cold, Hi component is
seen. Because its distance is not known, we considered various possibilities for the nature of GBT 1355+5439. Both the scenarios that
it is a tidal remnant near M101 and that it is a dark dwarf companion ofM101 meet difficulties. Neither do the data fit the properties of
known compact High-Velocity Clouds in the Galactic halo exactly, but we cannot entirely exclude this option and deeper observations
are required. We also considered the possibility that GBT 1355+5439 is a gas-rich dark minihalo in the outer regions of the Local
Group. Interestingly, it would then have similar properties as the clouds of a proposed Local Group population recently found in the
ALFALFA survey. In this case, the Hi mass of GBT 1355+5439 would be about a few times 105 M⊙, its size about 1 kpc, and the
dynamical mass Mdyn > 5 × 107 M⊙. However, if GBT 1355+5439 is a dark Local Group object, the internal kinematics of the Hi
appears to be different from that of gas-dominated, almost dark galaxies of similar size.
Key words. Galaxies : dwarf; Radio lines: galaxies
Block Card 5439 Lewis Avenue
No full textThis image was produced by the Auditor's Office in Lucas County, Ohio for tax assessment purposes. Associated dates are approximate. Descriptive terms related to this photograph include: 5439 Lewis Avenue (Toledo, Ohio) | Dwelling | Greenwood Park Area (Toledo, Ohio) | Cape Cod Styl
Block Card 5439 Regina Parkway
No full textThis image was produced by the Auditor's Office in Lucas County, Ohio for tax assessment purposes. Associated dates are approximate. Descriptive terms related to this photograph include: dwelling | 5439 Regina Parkway (Toledo, Ohio) | Garrison style | North Toledo (Toledo, Ohio) | Greenwood Area (Toledo, Ohio) | Regina Coeli Plat On
Block Card 5439 Douglas Road
No full textThis image was produced by the Auditor's Office in Lucas County, Ohio for tax assessment purposes. Associated dates are approximate. Descriptive terms related to this photograph include: Gable front houses | 5439 Douglas Road (Toledo, Ohio) | Dwelling | Cowan Place Addition (Toledo, Ohio) | Greenwood Park area (Toledo, Ohio) | Folk House Styl
LMC origin of the hyper-velocity star HE 0437-5439
Get PDFContext.Hyper-velocity stars move so fast that only a supermassive black hole
(SMBH) seems to be capable of accelerating them. Hence the Galactic centre (GC) is the
only place suggested as their origin. We discovered earlier that the object
HE 0437-5439 is a hyper-velocity star. However, this early B-type star is too
short-lived to have reached its current position in the Galactic halo if
ejected from the GC, except if it is a blue straggler.
Its proximity to the Large Magellanic Cloud (LMC) suggests an origin in this galaxy.
Aims.The chemical signatures of stars at the GC are significantly
different from those in the LMC. As a result, an accurate determination of the abundance
pattern of HE 0437-5439 will yield a new tight constraint on the place of
birth of this hyper-velocity star.
Methods.High-resolution spectra obtained with UVES on the VLT were analysed using state-of-the-art
NLTE modelling techniques.
Results.We determined abundances of individual elements to very high accuracy in
HE 0437-5439, as well as in two reference stars from the LMC and the solar
neighbourhood. The abundance pattern is not consistent
at all with that observed in stars near the GC, ruling out an origin from the GC.
However, there is a high degree of consistency with the LMC abundance pattern.
Our abundance results cannot rule out an origin in the outskirts of the
Galactic disk. However, we find the lifetime of HE 0437-5439 to be more
than three times shorter than the time of flight to the edge of the disk,
rendering a Galactic origin unlikely.
Conclusions.Only one SMBH is known to be present in the Galaxy and none in the LMC.
Hence the exclusion of an GC origin challenges the SMBH paradigm. We conclude
that there must be other mechanism(s) than the SMBH that accelerate stars to hyper-velocity
speed. We draw attention to dynamical ejection from dense massive
clusters, as recently proposed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Liquid chromatography-tandem mass spectrometry for the quantification of ripretinib and its metabolites DP-5439 in human plasma
Get PDFBackgroundRipretinib, a broad-spectrum tyrosine kinase inhibitor, has been approved for the treatment of advanced gastrointestinal stromal tumors in adult patients. Clinical studies have shown that higher in vivo exposure of ripretinib correlates with improved efficacy, highlighting the potential clinical significance of therapeutic drug monitoring. In this study, a simple and stable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was attempted to be established and validated for pharmacokinetic studies of ripretinib and its metabolite DP-5439 and therapeutic drug monitoring in human plasma.MethodRipretinib and DP-5439 were separated by chromatography using a Thermofisher Hypersil GOLDTM C18 HPLC column. The mobile phase for gradient elution is composed of 0.1% formic acid in water and acetonitrile. Multiple reaction monitoring was implemented along with electrospray ionization positive mode for detection. The ion pairs of ripretinib, DP-5439 and internal standard D8-ripretinib were m/z 510.1→m/z 417, m/z 496.11→m/z 402.9 and m/z 518.15→m/z 420, respectively. Plasma samples from ripretinib-treated patients of our hospital were collected for pharmacokinetic analysis.ResultsRipretinib and DP-5439 demonstrated a strong linear relationship over 10–5,000 μg/L (R2 > 0.99). Accuracy, precision, specificity, recoveries, matrix effect, stability, and dilution effect were all validated and found to meet the required criteria. Following validation, the method was utilized to determine plasma samples from patients treated with ripretinib. The median steady-state trough concentrations (Cmin, range) were 398.50 (66.98 ∼ 1,458.91) μg/L for ripretinib and 654.74 (30.71 ∼ 1,522.48) μg/L for DP-5439, with a total median concentration of 1,129.46 (140.95 ∼ 2,981.39) μg/L in patients receiving ripretinib at 150 mg once daily. Meanwhile, using the established methods, the study conducted pharmacokinetics studies on four patients with ripretinib and DP-5439.ConclusionThis study developed and validated a robust LC-MS/MS method for determining ripretinib and its metabolite DP-5439 in human plasma. Furthermore, the practicality of this method in clinical sample analysis was demonstrated. This approach can serve as an effective tool for the pharmacokinetics analysis and therapeutic drug monitoring in patients treated with ripretinib
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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