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Exploring the Connectome: Petascale Volume Visualization of Microscopy Data Streams
Beyer, J.,Hadwiger, M.,Al-Awami, A.,Won-Ki Jeong,Kasthuri, N.,Lichtman, J. W.,Pfister, H. IEEE 2013 IEEE computer graphics and applications Vol.33 No.4
<P>Recent advances in high-resolution microscopy let neuroscientists acquire neural-tissue volume data of extremely large sizes. However, the tremendous resolution and the high complexity of neural structures present big challenges to storage, processing, and visualization at interactive rates. A proposed system provides interactive exploration of petascale (petavoxel) volumes resulting from high-throughput electron microscopy data streams. The system can concurrently handle multiple volumes and can support the simultaneous visualization of high-resolution voxel segmentation data. Its visualization-driven design restricts most computations to a small subset of the data. It employs a multiresolution virtual-memory architecture for better scalability than previous approaches and for handling incomplete data. Researchers have employed it for a 1-teravoxel mouse cortex volume, of which several hundred axons and dendrites as well as synapses have been segmented and labeled.</P>
Hadwiger, M.,Beyer, J.,Won-Ki Jeong,Pfister, H. IEEE 2012 IEEE transactions on visualization and computer gr Vol.18 No.12
<P>This paper presents the first volume visualization system that scales to petascale volumes imaged as a continuous stream of high-resolution electron microscopy images. Our architecture scales to dense, anisotropic petascale volumes because it: (1) decouples construction of the 3D multi-resolution representation required for visualization from data acquisition, and (2) decouples sample access time during ray-casting from the size of the multi-resolution hierarchy. Our system is designed around a scalable multi-resolution virtual memory architecture that handles missing data naturally, does not pre-compute any 3D multi-resolution representation such as an octree, and can accept a constant stream of 2D image tiles from the microscopes. A novelty of our system design is that it is visualization-driven: we restrict most computations to the visible volume data. Leveraging the virtual memory architecture, missing data are detected during volume ray-casting as cache misses, which are propagated backwards for on-demand out-of-core processing. 3D blocks of volume data are only constructed from 2D microscope image tiles when they have actually been accessed during ray-casting. We extensively evaluate our system design choices with respect to scalability and performance, compare to previous best-of-breed systems, and illustrate the effectiveness of our system for real microscopy data from neuroscience.</P>
A study of preferential flow in heterogeneous media using random walk particle tracking
Chan-Hee Park,Christof Beyer,Sebastian Bauer,Olaf Kolditz 한국지질과학협의회 2008 Geosciences Journal Vol.12 No.3
We investigated the onset of preferential flow in heterogeneous porous media using the random walk particle tracking (RWPT) concept. The RWPT model is first used to analyze empirically the required number of particles to achieve accurate concentration distributions in two-dimensional homogeneous media and under uniform flow conditions. The analysis is then extended to randomly heterogeneous systems. By increasing the variance of log-normal hydraulic conductivity fields, the transition between homogeneous and preferential flows is observed. To analyze the degree of preferential flow in the porous media, we provide a diagram that consists of two dimensionless parameters: normalized travel time and distance. All the heterogeneous media synthetically generated show a linear relation in the diagram. The characteristic travel velocity increases with increasing heterogeneity. We found the diagram is a useful tool to analyze preferential flow.
Development of Industrial-Scale Fission 99Mo Production Process Using Low Enriched Uranium Target
이승곤,Gerd J. Beyer,이준식 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.3
Molybdenum-99 (99Mo) is the most important isotope because its daughter isotope,technetium-99m (99mTc), has been the most widely used medical radioisotope for morethan 50 years, accounting for > 80% of total nuclear diagnostics worldwide. In this review,radiochemical routes for the production of 99Mo, and the aspects for selecting a suitableprocess strategy are discussed from the historical viewpoint of 99Mo technology developments. Most of the industrial-scale 99Mo processes have been based on the fission of235U. Recently, important issues have been raised for the conversion of fission 99Mo targetsfrom highly enriched uranium to low enriched uranium (LEU). The development of newLEU targets with higher density was requested to compensate for the loss of 99Mo yield,caused by a significant reduction of 235U enrichment, from the conversion. As the dramaticincrement of intermediate level liquid waste is also expected from the conversion, aneffective strategy to reduce the waste generation from the fission 99Mo production isrequired. The mitigation of radioxenon emission from medical radioisotope productionfacilities is discussed in relation with the monitoring of nuclear explosions and comprehensivenuclear test ban. Lastly, the 99Mo production process paired with the Korea AtomicEnergy Research Institute's own LEU target is proposed as one of the most suitable processesfor the LEU target.
The Energy Dependence of the Electric Dipole Strength in Heavy Nuclei
A. R. Junghans,R. Beyer,G. Rusev,R. Schwengner,A. Wagner,E. Grosse 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
We investigate on the basis of new photon scattering measurements and photoneutron and average neutron resonance capture data how well Lorentzians adjusted to photoneutron data in the giant dipole resonances give a good description of the photon strength also below the neutron threshold. If deformation effects are properly taken into account it is verified that down to about 4 MeV for various nuclei with A > 80 the previously employed differentiation between deformed and non-deformed nuclei is no longer necessary.
Stavros Oikonomidis,Frank Beyer,Carolin Meyer,Christoph Tobias Baltin,Peer Eysel,Jan Bredow 대한척추외과학회 2020 Asian Spine Journal Vol.14 No.1
Study Design: Four orthopedic spine surgeons measured the radiological parameters of pedicle screws in the cervical spine using a postoperative computed tomography (CT) scan. Purpose: This study analyzed the insertion angle of CT-navigated insertion of pedicle screws in the subaxial cervical spine and classified them according to their position. Overview of Literature: Overall, a pedicle transverse angle of 33.6°–50.2° with a mean angle of 45° relative to the midline has been reported in the literature. Methods: The insertion angles of 87 pedicle screws inserted using CT-based navigation in the subaxial cervical spine were measured in the postoperative CT. The screw positioning was determined according to the modified Gertzbein and Robbins classification. Results: Total 89.3% (n=78) of the pedicle screws inserted using CT-based navigation showed good placement. The mean insertion angle of the pedicle screws that showed good positioning was 29.9°±9.9°. The pedicle screws showing bad positioning had a mean insertion angle of 26.8°±10.5° (p=0.157). The interobserver reliability showed a reliable measurement intraclass correlation coefficient: 0.994 (95% confidence interval, 0.992–0.996). Conclusions: The present results show that the insertion angle of the pedicle screws in the subaxial cervical spine was smaller than the actual pedicle transverse angle, as per the literature. One reason for this discrepancy could be that the navigation systems allow the insertion of cervical pedicle screws with a lower convergence.