Leibniz University of Hanover

About: Leibniz University of Hanover is a education organization based out in Hanover, Niedersachsen, Germany. It is known for research contribution in the topics: Finite element method & Computer science. The organization has 14283 authors who have published 29845 publications receiving 682152 citations.

Population Properties of Compact Objects from the Second LIGO-Virgo Gravitational-Wave Transient Catalog

Abstract: We report on the population of 47 compact binary mergers detected with a false-alarm rate of 0.01 are dynamically assembled. Third, we estimate merger rates, finding RBBH = 23.9-+8.614.3 Gpc-3 yr-1 for BBHs and RBNS = 320-+240490 Gpc-3 yr-1 for binary neutron stars. We find that the BBH rate likely increases with redshift (85% credibility) but not faster than the star formation rate (86% credibility). Additionally, we examine recent exceptional events in the context of our population models, finding that the asymmetric masses of GW190412 and the high component masses of GW190521 are consistent with our models, but the low secondary mass of GW190814 makes it an outlier.

Robot Collisions: A Survey on Detection, Isolation, and Identification

Abstract: Robot assistants and professional coworkers are becoming a commodity in domestic and industrial settings. In order to enable robots to share their workspace with humans and physically interact with them, fast and reliable handling of possible collisions on the entire robot structure is needed, along with control strategies for safe robot reaction. The primary motivation is the prevention or limitation of possible human injury due to physical contacts. In this survey paper, based on our early work on the subject, we review, extend, compare, and evaluate experimentally model-based algorithms for real-time collision detection, isolation, and identification that use only proprioceptive sensors. This covers the context-independent phases of the collision event pipeline for robots interacting with the environment, as in physical human–robot interaction or manipulation tasks. The problem is addressed for rigid robots first and then extended to the presence of joint/transmission flexibility. The basic physically motivated solution has already been applied to numerous robotic systems worldwide, ranging from manipulators and humanoids to flying robots, and even to commercial products.

Analyticity of periodic traveling free surface water waves with vorticity

Abstract: We prove that the prole of a periodic traveling wave propagating at the surface of water above a at bed in a ow with a real analytic vorticity must be real analytic, provided the wave speed exceeds the horizontal uid velocity throughout the ow. The real analyticity of each streamline be

Binary Black Hole Population Properties Inferred from the First and Second Observing Runs of Advanced LIGO and Advanced Virgo

Abstract: We present results on the mass, spin, and redshift distributions with phenomenological population models using the 10 binary black hole (BBH) mergers detected in the first and second observing runs completed by Advanced LIGO and Advanced Virgo. We constrain properties of the BBH mass spectrum using models with a range of parameterizations of the BBH mass and spin distributions. We find that the mass distribution of the more massive BH in such binaries is well approximated by models with no more than 1% of BHs more massive than 45 M and a power-law index of (90% credibility). We also show that BBHs are unlikely to be composed of BHs with large spins aligned to the orbital angular momentum. Modeling the evolution of the BBH merger rate with redshift, we show that it is flat or increasing with redshift with 93% probability. Marginalizing over uncertainties in the BBH population, we find robust estimates of the BBH merger rate density of R= (90% credibility). As the BBH catalog grows in future observing runs, we expect that uncertainties in the population model parameters will shrink, potentially providing insights into the formation of BHs via supernovae, binary interactions of massive stars, stellar cluster dynamics, and the formation history of BHs across cosmic time.

Cytotoxicity of 35 dental resin composite monomers/additives in permanent 3T3 and three human primary fibroblast cultures.

Abstract: It was the purpose of this investigation to determine the cytotoxic effects (ED50 concentrations) of 35 monomers or additives identified in commercial dental resin composites. Monolayers of permanent 3T3 cells and three primary human fibroblast types derived from oral tissues (gingiva, pulp, and periodontal ligament) were used as test systems. All substances were tested in concentrations ranging from 0.01 to 5.0 mM. In general, ED50 values varied from 0.06 to > 5 mM. Within the groups of co(monomers), initiators, and cointiators, severe (e.g., Bis-GMA, UDMA, DMBZ, and DMDTA) or moderate (HEMA, BEMA, CQ, DMPT, and DMAPE) cytotoxic effects could be evaluated. Within the group of reaction/decomposition products, only moderate or slight effects were found (ED50: 0.7 to > 5 mM). The inhibitor BHT, the contaminant TPSb, and the photostabilizer HMBP, however, were highly cytotoxic in all cell cultures. In addition, the ED50 values of DBPO and HMBP significantly varied (0.43-3.8 mM, respectively, and 0.44-3.07 mM) with the applied cell culture. Our comprehensive screening shows that for several of the highly cytotoxic composite components, less cytotoxic alternatives are available. Furthermore, there was no cell type identified which was consistently less or more sensitive to the toxic effects of the tested compounds than the others. Primary human periodontal ligament and pulp fibroblasts, however, were found to be more sensitive than 3T3 and gingival fibroblasts to alterations from most tested substances.