University of Vienna

About: University of Vienna is a education organization based out in Vienna, Austria. It is known for research contribution in the topics: Population & Context (language use). The organization has 44686 authors who have published 95840 publications receiving 2907492 citations.

Cohesin ensures bipolar attachment of microtubules to sister centromeres and resists their precocious separation.

Abstract: The multisubunit protein complex cohesin is required to establish cohesion between sister chromatids during S phase and to maintain it during G2 and M phases. Cohesin is essential for mitosis, and even partial defects cause very high rates of chromosome loss. In budding yeast, cohesin associates with specific sites which are distributed along the entire length of a chromosome but are more dense in the vicinity of the centromere. Real-time imaging of individual centromeres tagged with green fluorescent protein suggests that cohesin bound to centromeres is important for bipolar attachment to microtubules. This cohesin is, however, incapable of resisting the consequent force, which leads to sister centromere splitting and chromosome stretching. Meanwhile, cohesin bound to sequences flanking the centromeres prevents sister chromatids from completely unzipping and is required to pull back together sister centromeres that have already split. Cohesin therefore has a central role in generating a dynamic tension between microtubules and sister chromatid cohesion at centromeres, which lasts until chromosome segregation is finally promoted by separin-dependent cleavage of the cohesin subunit Scc1p.

Ascent of dinosaurs linked to an iridium anomaly at the Triassic-Jurassic boundary.

Abstract: Analysis of tetrapod footprints and skeletal material from more than 70 localities in eastern North America shows that large theropod dinosaurs appeared less than 10,000 years after the Triassic-Jurassic boundary and less than 30,000 years after the last Triassic taxa, synchronous with a terrestrial mass extinction. This extraordinary turnover is associated with an iridium anomaly (up to 285 parts per trillion, with an average maximum of 141 parts per trillion) and a fern spore spike, suggesting that a bolide impact was the cause. Eastern North American dinosaurian diversity reached a stable maximum less than 100,000 years after the boundary, marking the establishment of dinosaur-dominated communities that prevailed for the next 135 million years. One of the most striking events in the Mesozoic was the rise to dominance of dinosaurs in terrestrial ecosystems. The cause and timing of their early Mesozoic ascent have been debated (1‐4), with difficulties in global correlation and low sampling density limiting the utility of global compilations and obscuring relations to possible forcing mechanisms. However, terrestrial vertebrate assemblages in eastern North America are temporally better constrained than elsewhere and provide high-resolution biological and geochemical data bearing on this issue. This region was within the tropics during the Triassic and contained rift valleys, which were formed during the incipient fragmentation of Pangea. These basins contain kilometer-thick sections of continental strata, termed the Newark Supergroup, which have recorded the rise of dinosaurs across 15° of paleolatitude (5). Milankovitchtype climate cycles permeate the lacustrine strata of these basins, and in conjunction with paleomagnetic reversal stratigraphy, all of the

Optical measurement of the axial eye length by laser Doppler interferometry.

Abstract: A new technique has been developed to determine the axial length of the human eye in vivo. Based on laser interferometry in conjunction with the Doppler technique, it uses partially coherent light. This new technique complies with laser safety regulations. High accuracy is achieved, the optical length (OL) can be determined within +/- 30 microns, and the reproducibility of the geometric eye length is greater than +/- 25 microns. Possible errors are discussed. First comparisons with the ultrasound technique yield good agreement for emmetropic subjects and for subjects with a myopia of up to 10 diopters. The advantages of the laser doppler interferometry (LDI) technique are high accuracy, high transversal resolution, and more comfort for the patient (it is a noncontact method; no anesthesia is needed). Possible future applications of LDI, like measurements of fundus profiles and of retinal thickness, are mentioned.

Identification of "premyelination" by diffusion-weighted MRI.

Abstract: Objective The purpose of this study was to compare white matter maturation as demonstrated with diffusion-weighted MRI and with myelin-sensitive histological staining. Materials and methods The diffusion-, T1-, and T2-weighted SE MRI at 4.7 T was performed weekly in a total of 16 rat pups, aged from 5 days to 8 weeks, 2 animals evaluated per week. Heavily diffusion-weighted sequences were obtained with the diffusion-sensitizing gradient switched alternately in two orthogonal directions. To enhance signal intensity of anisotropic structures, a synthesized image (referred to as the "anisotropy index map") was constructed from the ratio of pairs of images acquired with diffusion sensitization of identical magnitude but orthogonal direction sensitivity. The anisotropy index maps were used for comparison with T1-weighted and heavily T2-weighted SE sequences and histological sections, respectively. Results The first evidence of diffusion anisotropy on anisotropy index maps preceded initial myelin as well as neurofibril staining by 5-12 days and T2 shortening by 2 weeks. The T1-weighted sequences did not yield visible changes and were not helpful for the assessment of ongoing white matter maturation in this model. Conclusion Magnetic resonance imaging signal intensity changes based on anisotropic water diffusion were demonstrated in regions of unmyelinated cerebral white matter tracts of albino rat pups before the onset of histologically detectable myelin. The ability of in vivo mapping of premyelinating white matter maturation indicates a new diagnostic use of MRI in evaluating cerebral white matter maturation.

At what scales do climate variability and land cover change impact on flooding and low flows

Abstract: 1 Institute of Hydraulic and Water Resources Engineering, Vienna University of Technology, Karlsplatz 13, A-1040 Vienna, Austria 2 UMR HydroSciences Montpellier, France 3 UNESCO Division of Water Sciences, Paris, France 4 University of Vienna, Austria 5 USDA-ARS-SWRC, Tucson, AZ, USA 6 FIMCM-ESPOL, Campus Gustavo Galindo, Guayaquil, Ecuador 7 GeoForschungsZentrum Potsdam, Germany 8 CSIRO Land and Water, Glen Osmond, Australia 9 Slovak University of Technology, Bratislava, Slovakia