2,089 research outputs found
Physics-based Simulation of Continuous-Wave LIDAR for Localization, Calibration and Tracking
Light Detection and Ranging (LIDAR) sensors play an important role in the
perception stack of autonomous robots, supplying mapping and localization
pipelines with depth measurements of the environment. While their accuracy
outperforms other types of depth sensors, such as stereo or time-of-flight
cameras, the accurate modeling of LIDAR sensors requires laborious manual
calibration that typically does not take into account the interaction of laser
light with different surface types, incidence angles and other phenomena that
significantly influence measurements. In this work, we introduce a physically
plausible model of a 2D continuous-wave LIDAR that accounts for the
surface-light interactions and simulates the measurement process in the Hokuyo
URG-04LX LIDAR. Through automatic differentiation, we employ gradient-based
optimization to estimate model parameters from real sensor measurements.Comment: Published at ICRA 202
Primary cilia on endothelial cells : component of the shear stress sensor localized to athero-prone flow areas
Blood-flow-induced shear stress plays an important role in cardiovascular development and disease. How endothelial cells sense shear stress remains to be elucidated. We postulated that the primary cilium is a component of the endothelial shear sensor. This luminal cell protrusion contains microtubules and is connected to the microtubular cytoskeleton. We identified cilia on endothelial cells of the embryonic heart in areas of low or oscillatory shear stress. This shear-related distribution is reminiscent of the distribution of atherosclerotic lesions in the adult arterial system, as lesions develop at sites of low or oscillating shear (athero-prone flow). Ciliated endothelial cells are exclusively present at these atherosclerotic predilection sites in adult mice. Athero-prone (oscillatory) but not athero-protective (steady or pulsatile) flow induces ciliation of cultured endothelial cells. Moreover, the endothelial shear response is dependent on the microtubular cytoskeleton and primary cilia sensitise the endothelium for shear. Taken together, these data demonstrate that primary cilia are induced by athero-prone flow and that ciliated cells are more sensitive to shear stress. We conclude that the endothelial biosensor for shear stress is the microtubular cytoskeleton and that the attached primary cilium functions as a signal amplifier in areas subjected to athero-prone flow.UBL - phd migration 201
Dual endothelin-converting enzyme/neutral endopeptidase blockade in rats with D-galactosamine-induced liver failure
Secondary activation of the endothelin system is thought to be involved in toxic liver injury. This study tested the hypothesis that dual endothelin-converting enzyme / neutral endopeptidase blockade might be able to attenuate acute toxic liver injury
Synchronization in a neuronal feedback loop through asymmetric temporal delays
We consider the effect of asymmetric temporal delays in a system of two
coupled Hopfield neurons. For couplings of opposite signs, a limit cycle
emerges via a supercritical Hopf bifurcation when the sum of the delays reaches
a critical value. We show that the angular frequency of the limit cycle is
independent of an asymmetry in the delays. However, the delay asymmetry
determines the phase difference between the periodic activities of the two
components. Specifically, when the connection with negative coupling has a
delay much larger than the delay for the positive coupling, the system
approaches in-phase synchrony between the two components. Employing variational
perturbation theory (VPT), we achieve an approximate analytical evaluation of
the phase shift, in good agreement with numerical results.Comment: 5 pages, 4 figure
Metacognitieve therapie voor de obsessieve-compulsieve stoornis: Theorie, behandeling en implicaties voor de praktijk
Metacognitieve therapie voor de obsessieve-compulsieve stoornis: Theorie, behandeling en implicaties voor de praktijk
Scaling in a Nonconservative Earthquake Model of Self-Organised Criticality
We numerically investigate the Olami-Feder-Christensen model for earthquakes
in order to characterise its scaling behaviour. We show that ordinary finite
size scaling in the model is violated due to global, system wide events.
Nevertheless we find that subsystems of linear dimension small compared to the
overall system size obey finite (subsystem) size scaling, with universal
critical coefficients, for the earthquake events localised within the
subsystem. We provide evidence, moreover, that large earthquakes responsible
for breaking finite size scaling are initiated predominantly near the boundary.Comment: 6 pages, 6 figures, to be published in Phys. Rev. E; references
sorted correctl
Metacognitieve therapie voor de obsessieve-compulsieve stoornis
De obsessieve-compulsieve stoornis (OCS) is een veelvoorkomende en invaliderende stoornis. Cognitieve gedragstherapie (CGT) in de vorm van exposure met responspreventie (ERP) is de psychologische behandeling van eerste voorkeur. Ondanks de aangetoonde werkzaamheid van ERP is verbetering van de effectivitei
Vortex microavalanches in superconducting Pb thin films
Local magnetization measurements on 100 nm type-II superconducting Pb thin
films show that flux penetration changes qualitatively with temperature. Small
flux jumps at the lowest temperatures gradually increase in size, then
disappear near T = 0.7Tc. Comparison with other experiments suggests that the
avalanches correspond to dendritic flux protrusions. Reproducibility of the
first flux jumps in a decreasing magnetic field indicates a role for defect
structure in determining avalanches. We also find a temperature-independent
final magnetization after flux jumps, analogous to the angle of repose of a
sandpile.Comment: 6 pages, 5 figure
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