University of Zurich

About: University of Zurich is a education organization based out in Zurich, Switzerland. It is known for research contribution in the topics: Population & Transplantation. The organization has 50842 authors who have published 124042 publications receiving 5304521 citations. The organization is also known as: UZH & Uni Zurich.

Clumps and streams in the local dark matter distribution

Abstract: The standard cosmological model includes the presumption that cold dark matter plays a major part in large-scale mass distribution in the Universe from the Big Bang to the present. Though successful in explaining large-scale events, until now simulations of galaxy formation using the cold dark matter model have failed to resolve certain smaller-scale structures. Now Diemand et al. have simulated the assembly of the dark matter 'halo' of the Milky Way at much better resolution than has been possible previously. The model then produces thousands of clumps surviving within the inner halo, some of them in the vicinity of the Solar System. In cold dark matter cosmological models, structures form and grow by merging of smaller units, previous simulations have shown that such merging is incomplete as the inner cores of halos survive and orbit as 'subhalos' within their hosts. This paper reports a simulation that resolves such substructure in the very inner regions of the Galactic halo. Hundreds of very concentrated dark matter clumps survive near the solar circle, as well as numerous cold streams. In cold dark matter cosmological models1,2, structures form and grow through the merging of smaller units3. Numerical simulations have shown that such merging is incomplete; the inner cores of haloes survive and orbit as ‘subhaloes’ within their hosts4,5. Here we report a simulation that resolves such substructure even in the very inner regions of the Galactic halo. We find hundreds of very concentrated dark matter clumps surviving near the solar circle, as well as numerous cold streams. The simulation also reveals the fractal nature of dark matter clustering: isolated haloes and subhaloes contain the same relative amount of substructure and both have cusped inner density profiles. The inner mass and phase-space densities of subhaloes match those of recently discovered faint, dark-matter-dominated dwarf satellite galaxies6,7,8, and the overall amount of substructure can explain the anomalous flux ratios seen in strong gravitational lenses9,10. Subhaloes boost γ-ray production from dark matter annihilation by factors of 4 to 15 relative to smooth galactic models. Local cosmic ray production is also enhanced, typically by a factor of 1.4 but by a factor of more than 10 in one per cent of locations lying sufficiently close to a large subhalo. (These estimates assume that the gravitational effects of baryons on dark matter substructure are small.)

A community-derived classification for extant lycophytes and ferns

Abstract: Phylogeny has long informed pteridophyte classification. As our ability to infer evolutionary trees has improved, classifications aimed at recognizing natural groups have become increasingly predic ...

Protter: interactive protein feature visualization and integration with experimental proteomic data

Abstract: Summary: The ability to integrate and visualize experimental proteomic evidence in the context of rich protein feature annotations represents an unmet need of the proteomics community. Here we present Protter, a web-based tool that supports interactive protein data analysis and hypothesis generation by visualizing both annotated sequence features and experimental proteomic data in the context of protein topology. Protter supports numerous proteomic file formats and automatically integrates a variety of reference protein annotation sources, which can be readily extended via modular plugins. A built-in export function produces publication-quality customized protein illustrations, also for large datasets. Visualizations of surfaceome datasets show the specific utility of Protter for the integrated visual analysis of membrane proteins and peptide selection for targeted proteomics. Availability and implementation: The Protter web application is available at http://wlab.ethz.ch/protter. Source code and installation instructions are available at http://ulo.github.io/Protter/.

Microglia in the adult brain arise from Ly-6ChiCCR2+ monocytes only under defined host conditions

Abstract: Microglia are crucially important myeloid cells in the CNS and constitute the first immunological barrier against pathogens and environmental insults. The factors controlling microglia recruitment from the blood remain elusive and the direct circulating microglia precursor has not yet been identified in vivo. Using a panel of bone marrow chimeric and adoptive transfer experiments, we found that circulating Ly-6C(hi)CCR2(+) monocytes were preferentially recruited to the lesioned brain and differentiated into microglia. Notably, microglia engraftment in CNS pathologies, which are not associated with overt blood-brain barrier disruption, required previous conditioning of brain (for example, by direct tissue irradiation). Our results identify Ly-6C(hi)CCR2(+) monocytes as direct precursors of microglia in the adult brain and establish the importance of local factors in the adult CNS for microglia engraftment.

Hazardous times for monetary policy : What do twenty-three million bank loans say about the effects of monetary policy on credit risk-taking?

Abstract: We identify the effects of monetary policy on credit risk-taking with an exhaustive credit register of loan applications and contracts. We separate the changes in the composition of the supply of credit from the concurrent changes in the volume of supply and quality, and the volume of demand. We employ a two-stage model that analyzes the granting of loan applications in the first stage and loan outcomes for the applications granted in the second stage, and that controls for both observed and unobserved, time-varying, firm and bank heterogeneity through time*firm and time*bank fixed effects. We find that a lower overnight interest rate induces lowly capitalized banks to grant more loan applications to ex ante risky firms and to commit larger loan volumes with fewer collateral requirements to these firms, yet with a higher ex post likelihood of default. A lower long-term interest rate and other relevant macroeconomic variables have no such effects.