1,722,110 research outputs found
Baryons in Dark Matter Halos
No full textThe existence of Dark Matter (DM) has been known since the 30's of the last century. The first cognitions from motions of galaxies in clusters and by the kinematics of individual galaxies were followed by systematic investigations, primarily via galaxy rotation curves. Since the mid 90's, observations can be confronted with models defined in specific galaxy formation scenarios, in particular with the output of numerical simulations performed in the framework of (Lambda) Cold Dark Matter (CDM). The great success of these models is that they reproduce the large-scale structure with great success, while they - maybe not surprisingly - seem to fail to be equally successful in describing the evolution of the universe on smaller, i.e. cluster and galaxy scales. These developments were parallelled by breathtaking advancements in cosmology. Since the precision measurement of the spectrum of the cosmic microwave background (CMB) with COBE, subsequent experiments devoted to the CMB anisotropy (Boomerang, WMAP) have led to what is called 'precision cosmology'. This implies that we are in the position of validating (numerical) models to a high degree. At the same time, we are witnessing amazing developments in observational astronomy, which allow to explore the universe back into the epoch of re-ionization, thereby subjecting models to further critical and crucial tests, the last steps expected to be taken in the near future. All of this looking nice at first glance, it does not mean that we may comfortably sit back and consider most of the riddles solved. In fact, it must be a worry to any astrophysicist that both, DM and Dark Energy remain nothing but hypotheses as long as no particle has been detected in lab experiments yet. Are they just 'epicycles' like those resorted to prior to Kepler to explain the motions of planets? Nearly ten years of critical validation of CDM models have, apart from a lot of success, resulted in what has been coined as the "first and second CDM crisis", i.e. the failure of theory to explain the mass spectrum of dark satellites around big galaxies on large scales, and the (partial) absence of cusps in the dense inner part of galaxy halos. This obviously calls for continuing efforts in both, observational and theoretical fields. The conference Baryons in Dark Matter Halos we announce here is jointly organized by the Bochum /Bonn graduate research school "Galaxy Groups as Laboratories of Baryonic and Dark Matter" and SISSA is meant to bring together experts from the whole world working in the fields outlined above, trying to make a critical assessment of what has been achieved and to identify the problems that we are faced with. Invited reviews will be given to summarise the state-of-the-art, in particular to the participating graduate students and to scientists working in these fields. The event will provide the participating students with the opportunity to present their own work and advertise it to other participants. Their activity should also be understood as a stimulus for future collaborations or intensify the existing ones. In this sense, the event is meant to be between a summer school and a workshop. We would like that this meeting, that takes place in the inviting and picturesque location of Cittanova/Novigrad, Istria, will be featured by the same spirit present in many of the previous meetings and workshops of the graduate school. Our first aim for the five-day meeting is that the so-called "paradigm of hierarchical structure formation" be subjected to a lively and critical discussion (with strong involvement of the students!). A second aim is to identify future directions of research leading to further progress in our understanding of structure formation and evolution of galaxies. It is our aim that during the five-day meeting that the so-called paradigm of hierarchical structure formation will be subjected to a lively and critical discussion (with strong involvement of the students!), with the cosmological concordance model in the background. Future directions of research shall be identified that will lead to further progress in understanding structure formation and the evolution of galaxies. We hope that this meeting, taking place in the inviting location of Cittanova/Novigrad at the picturesque Istrian coast of Croatia, will be featured by the same spirit as was present in many of the previous meetings and workshops of the graduate school
Sanfilippo syndrome type C: deficiency of acetyl-CoA: α-glucosaminide N-acetyltransferase in skin fibroblasts
No full textRemoval of N-sulfated glucosamine residues during degradation of heparan sulfate is accomplished by the sequential action of three enzymes. Action of sulfamidase resuits in the formation of α-glucosaminide residues. Removal of these groups requires conversion to α-N-acetylglucosaminide by the action of an acetyltransferase in the presence of acetyl- CoA, followed by hydrolysis by α-N-acetylglucosaminidase. In fibroblast homogenates from three patients with Sanfilippo syndrome type C (mucopolysaccharidosis III C), a biochemical variant of the Sanfilippo syndrome, complete deficiency of the acetylCoA:α-glucosaminide N-acetyltransferase activity was detected. Activities of all lysosomal hydrolases known so far to degrade mucopolysaccharides, including those of sulfamidase and α-N-acetyl lucosaminidase, were in the range of controls. Acetyl-CoA:α-glucosaminide N-acetyltransferase activity was normal in fibroblasts of patients with other genetic mucopolysaccharidoses, including Sanfilippo syndrome A and B
Sanfilippo syndrome type C: deficiency of acetyl-CoA: α-glucosaminide N-acetyltransferase in skin fibroblasts
No full textRemoval of N-sulfated glucosamine residues during degradation of heparan sulfate is accomplished by the sequential action of three enzymes. Action of sulfamidase resuits in the formation of α-glucosaminide residues. Removal of these groups requires conversion to α-N-acetylglucosaminide by the action of an acetyltransferase in the presence of acetyl- CoA, followed by hydrolysis by α-N-acetylglucosaminidase. In fibroblast homogenates from three patients with Sanfilippo syndrome type C (mucopolysaccharidosis III C), a biochemical variant of the Sanfilippo syndrome, complete deficiency of the acetylCoA:α-glucosaminide N-acetyltransferase activity was detected. Activities of all lysosomal hydrolases known so far to degrade mucopolysaccharides, including those of sulfamidase and α-N-acetyl lucosaminidase, were in the range of controls. Acetyl-CoA:α-glucosaminide N-acetyltransferase activity was normal in fibroblasts of patients with other genetic mucopolysaccharidoses, including Sanfilippo syndrome A and B
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Unveiling Dark Matter with HI and Halpha Data - Observational Problems
No full textWe present combined Halpha+HI rotation curves for a sample of spiral galaxies. Most of the velocity profiles (spectra at single points) in these galaxies are asymmetric, preventing the use of standard methods like the first moment analysis and the single Gaussian fitting. We thus propose a method similar to the Envelope-Tracing method (Sofue & Rubin 2001) to analyse those profiles from which we obtain HI rotation curves in good agreement with the Halpha rotation curves. These final rotation curves provide the required high resolution in the inner parts of the galaxies, but also extend out to typically 2-3 optical radii. They will hence allow us to investigate the distribution of dark matter
Variations on the Author
Full text link“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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