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排序方式: 共有3199条查询结果,搜索用时 125 毫秒
21.
The problem of packing circles into a domain of prescribed topology is considered. The circles need not have equal radii. The Collins-Stephenson algorithm computes such a circle packing. This algorithm is parallelized in two different ways and its performance is reported for a triangular, planar domain test case. The implementation uses the highly parallel graphics processing unit (GPU) on commodity hardware. The speedups so achieved are discussed based on a number of experiments. 相似文献
22.
We describe RTblob, a high speed vision system that detects objects in cluttered scenes based on their color and shape at
a speed of over 800 frames/s. Because the system is available as open-source software and relies only on off-the-shelf PC
hardware components, it can provide the basis for multiple application scenarios. As an illustrative example, we show how
RTblob can be used in a robotic table tennis scenario to estimate ball trajectories through 3D space simultaneously from four
cameras images at a speed of 200 Hz. 相似文献
23.
Phan Alex Truong Phuong Schade Christoph Vasan Aditya Friend James Talke Frank E. 《Microsystem Technologies》2021,27(6):2473-2479
Microsystem Technologies - “Zero drift” behavior of an optical intraocular pressure sensor is studied using an analytical model based on the deflection of a circular membrane. Results... 相似文献
24.
Christoph Beierle Gabriele Kern-Isberner 《Annals of Mathematics and Artificial Intelligence》2012,65(2-3):123-158
Different forms of semantics have been proposed for conditionals of the form “Usually, if A then B”, ranging from quantitative probability distributions to qualitative approaches using plausibility orderings, possibility distributions, or conditional objects. Atomic-bound systems, also called big-stepped probabilities, allow qualitative reasoning with probabilities, aiming at bridging the gap between qualitative and quantitative argumentation and providing a model for the nonmonotonic reasoning system P. By using Goguen and Burstall’s notion of institutions for the formalization of logical systems, we elaborate precisely which formal connections exist among big-stepped probabilities, standard probabilities, and qualitative logics. Based on our investigations, we also develop two variants of conditional objects, one of them having a simpler semantics while still providing a model for system P. 相似文献
25.
Krishnan H Garth C Gühring J Gülsün MA Greiser A Joy KI 《IEEE transactions on visualization and computer graphics》2012,18(6):966-977
Many flow visualization techniques, especially integration-based methods, are problematic when the measured data exhibit noise and discretization issues. Particularly, this is the case for flow-sensitive phase-contrast magnetic resonance imaging (PC-MRI) data sets which not only record anatomic information, but also time-varying flow information. We propose a novel approach for the visualization of such data sets using integration-based methods. Our ideas are based upon finite-time Lyapunov exponents (FTLE) and enable identification of vessel boundaries in the data as high regions of separation. This allows us to correctly restrict integration-based visualization to blood vessels. We validate our technique by comparing our approach to existing anatomy-based methods as well as addressing the benefits and limitations of using FTLE to restrict flow. We also discuss the importance of parameters, i.e., advection length and data resolution, in establishing a well-defined vessel boundary. We extract appropriate flow lines and surfaces that enable the visualization of blood flow within the vessels. We further enhance the visualization by analyzing flow behavior in the seeded region and generating simplified depictions. 相似文献
26.
In this paper, we present a formulation of the quaternion constraint for rigid body rotations in the form of a standard perfect
bilateral mechanical constraint, for which the associated Lagrangian multiplier has the meaning of a constraint force. First,
the equations of motion of a scalable body are derived. A scalable body has three translational, three rotational, and one
uniform scaling degree of freedom. As generalized coordinates, an unconstrained quaternion and a displacement vector are used.
To the scalable body, a perfect bilateral constraint is added, restricting the quaternion to unit length and making the body
rigid. This way a quaternion based differential algebraic equation (DAE) formulation for the dynamics of a rigid body is obtained,
where the 7×7 mass matrix is regular and the unit length restriction of the quaternion is enforced by a mechanical constraint.
Finally, the equations of motion in the form of a DAE are linked to the Newton–Euler equations of motion of a rigid body.
The rigid body DAE formulation is useful for the construction of (energy) consistent integrators. 相似文献
27.
Johannes Klopf Christine Brostjan Wolf Eilenberg Christoph Neumayer 《International journal of molecular sciences》2021,22(2)
Neutrophils are primary effector cells of innate immunity and fight infection by phagocytosis and degranulation. Activated neutrophils also release neutrophil extracellular traps (NETs) in response to a variety of stimuli. These NETs are net-like complexes composed of cell-free DNA, histones and neutrophil granule proteins. Besides the evolutionarily conserved mechanism to capture and eliminate pathogens, NETs are also associated with pathophysiological processes of various diseases. Here, we elucidate the mechanisms of NET formation and their different implications in disease. We focused on autoinflammatory and cardiovascular disorders as the leading cause of death. Neutrophil extracellular traps are not only present in various cardiovascular diseases but play an essential role in atherosclerotic plaque formation, arterial and venous thrombosis, as well as in the development and progression of abdominal aortic aneurysms. Furthermore, NETosis can be considered as a source of autoantigens and maintains an inflammatory milieu promoting autoimmune diseases. Indeed, there is further need for research into the balance between NET induction, inhibition, and degradation in order to pharmacologically target NETs and their compounds without impairing the patient’s immune defense. This review may be of interest to both basic scientists and clinicians to stimulate translational research and innovative clinical approaches. 相似文献
28.
Jan H. Dring Julian Schrter Jerome Jüngling Saskia Biskup Kerstin A. Klotz Thomas Bast Tobias Dietel G. Christoph Korenke Sophie Christoph Heiko Brennenstuhl Guido Rubboli Rikke S. Mller Gaetan Lesca Yves Chaix Stefan Klker Georg F. Hoffmann Johannes R. Lemke Steffen Syrbe 《International journal of molecular sciences》2021,22(6)
Pathogenic variants in KCNA2, encoding for the voltage-gated potassium channel Kv1.2, have been identified as the cause for an evolving spectrum of neurological disorders. Affected individuals show early-onset developmental and epileptic encephalopathy, intellectual disability, and movement disorders resulting from cerebellar dysfunction. In addition, individuals with a milder course of epilepsy, complicated hereditary spastic paraplegia, and episodic ataxia have been reported. By analyzing phenotypic, functional, and genetic data from published reports and novel cases, we refine and further delineate phenotypic as well as functional subgroups of KCNA2-associated disorders. Carriers of variants, leading to complex and mixed channel dysfunction that are associated with a gain- and loss-of-potassium conductance, more often show early developmental abnormalities and an earlier onset of epilepsy compared to individuals with variants resulting in loss- or gain-of-function. We describe seven additional individuals harboring three known and the novel KCNA2 variants p.(Pro407Ala) and p.(Tyr417Cys). The location of variants reported here highlights the importance of the proline(405)–valine(406)–proline(407) (PVP) motif in transmembrane domain S6 as a mutational hotspot. A novel case of self-limited infantile seizures suggests a continuous clinical spectrum of KCNA2-related disorders. Our study provides further insights into the clinical spectrum, genotype–phenotype correlation, variability, and predicted functional impact of KCNA2 variants. 相似文献
29.
Dr. Armin Welker Dr. Christian Kersten Dr. Christin Müller Dr. Ramakanth Madhugiri Collin Zimmer Patrick Müller Robert Zimmermann Stefan Hammerschmidt Hannah Maus Prof. John Ziebuhr Prof. Christoph Sotriffer Prof. Tanja Schirmeister 《ChemMedChem》2021,16(2):340-354
Inhibition of coronavirus (CoV)-encoded papain-like cysteine proteases (PLpro) represents an attractive strategy to treat infections by these important human pathogens. Herein we report on structure-activity relationships (SAR) of the noncovalent active-site directed inhibitor (R)-5-amino-2-methyl-N-(1-(naphthalen-1-yl)ethyl) benzamide ( 2 b ), which is known to bind into the S3 and S4 pockets of the SARS-CoV PLpro. Moreover, we report the discovery of isoindolines as a new class of potent PLpro inhibitors. The studies also provide a deeper understanding of the binding modes of this inhibitor class. Importantly, the inhibitors were also confirmed to inhibit SARS-CoV-2 replication in cell culture suggesting that, due to the high structural similarities of the target proteases, inhibitors identified against SARS-CoV PLpro are valuable starting points for the development of new pan-coronaviral inhibitors. 相似文献
30.
Sulfuric acid-catalyzed hydrolysis of cellulose commonly isolates cellulose nanocrystals (CNCs). Neutralizing the reactant solution with sodium hydroxide facilitates efficient downstream processing, but residual salt remains in the product. This study examines the reinforcing effects of CNCs from suspensions that contain residual salt on the mechanical properties of thermoplastic starch nanocomposites. By reinforcing starch films with up to 5 wt% CNCs, stiffness and strength are improved by 118% and 79%, respectively, indicating a good dispersion of CNCs in the starch matrix. Compared to nanocomposites incorporating salt-free CNCs, the remaining salt has no significant impact on the material's mechanical performance. The results indicate great potential of CNCs containing residual salt as biobased, low-cost nanofiller in hydrophilic polymer matrices. 相似文献