47 research outputs found
Simultaneous detection of cerebral blood perfusion and cerebral edema using sweptâsource optical coherence tomography
The progression of ischemic cerebral edema (CE) is closely related to the level of cerebral blood perfusion (CBP) and affects each other. Simultaneous detection of CBP and CE is helpful in understanding the mechanisms of ischemic CE development. In this article, a wide field of view sweptâsource optical coherence tomography system was used to detect CE status and CBP levels simultaneously in middle cerebral artery occlusion rats. Images reflecting these two physiological states can be reconstructed with only one Câscan. We quantify these two physiological states into four parameters, which contain two vascular parameters (vascular displacement distance and vascular perfusion density) and two edema parameters (optical attenuation coefficient and edema area). The association between the two vascular parameters and the two edema parameters was analyzed. The results show that there is a strong linear relationship between blood flow parameters and edema parameters. This work provides a new option for CE inâvivo detection, and is very likely to play an important role in the development of relevant drugs or in selection of treatment options.In this article, a wide field of view sweptâsource optical coherence tomography system was used to detect cerebral edema status and cerebral blood perfusion levels simultaneously in middle cerebral artery occlusion rats. Images reflecting these two physiological states can be reconstructed with only one Câscan. We quantify these two physiological states into four parameters, which contain two vascular parameters and two edema parameters. The association between the two vascular parameters and the two edema parameters was analyzed. The results show that there is a strong linear relationship between blood flow parameters and edema parameters.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153673/1/jbio201960087_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153673/2/jbio201960087.pd
3D Nondestructive Visualization and Evaluation of TRISO Particles Distribution in HTGR Fuel Pebbles Using Cone-Beam Computed Tomography
A nonuniform distribution of tristructural isotropic (TRISO) particles within a high-temperature gas-cooled reactor (HTGR) pebble may lead to excessive thermal gradients and nonuniform thermal expansion during operation. If the particles are closely clustered, local hotspots may form, leading to excessive stresses on particle layers and an increased probability of particle failure. Although X-ray digital radiography (DR) is currently used to evaluate the TRISO distributions in pebbles, X-ray DR projection images are two-dimensional in nature, which would potentially miss some details for 3D evaluation. This paper proposes a method of 3D visualization and evaluation of the TRISO distribution in HTGR pebbles using cone-beam computed tomography (CBCT): first, a pebble is scanned on our high-resolution CBCT, and 2D cross-sectional images are reconstructed; secondly, all cross-sectional images are restructured to form the 3D model of the pebble; then, volume rendering is applied to segment and display the TRISO particles in 3D for visualization and distribution evaluation. For method validation, several pebbles were scanned and the 3D distributions of the TRISO particles within the pebbles were produced. Experiment results show that the proposed method provides more 3D than DR, which will facilitate pebble fabrication research and production quality control
Few-photon single ionization of cold rubidium in the over-the-barrier regime
Photoionization of the rubidium (Rb) atoms cooled in a magneto-optical trap,
characterized by the coexistence of the ground 5 and the excited
5 states, is investigated experimentally and theoretically with the
400 nm femtosecond laser pulses at intensities of W/cm -
W/cm. Recoil-ion momentum distribution (RIMD) of Rb
exhibits rich ring-like structures and their energies correspond to one-photon
ionization of the 5 state, two-photon and three-photon ionizations of
the 5 state, respectively. With the increasing of , we find that
experimental signals near zero-momentum (NZM) in RIMDs resulted from the
5 state enhance dramatically and its peaked Rb momenta dwindle
obviously while that from the 5 state is maintained. Meanwhile, the
ion-yield ratio of the 5 over the 5 states varies from to
as increases. These features indicate a transition from
perturbative ionization to strong-perturbative ionization for the 5
state. Numerical simulations by solving the time-dependent Schr\"odinger
equation (TDSE) can qualitatively explain the measurements of RIMD, photoion
angular distributions, as well as ion-yield ratio. However, some discrepancies
still exist, especially for the NZM dip, which could stem from the
electron-electron correlation that is neglected in the present TDSE simulations
since we have adopted the single-active-electron approximation
Ellipticity-dependent sequential over-barrier ionization of cold rubidium
We perform high-resolution measurements of momentum distribution on Rb
recoil ions up to charge state , where laser-cooled rubidium atoms are
ionized by femtosecond elliptically polarized lasers with the pulse duration of
35 fs and the intensity of 3.310 W/cm in the over-barrier
ionization (OBI) regime. The momentum distributions of the recoil ions are
found to exhibit multi-band structures as the ellipticity varies from the
linear to circular polarizations. The origin of these band structures can be
explained quantitatively by the classical OBI model and dedicated classical
trajectory Monte Carlo simulations with Heisenberg potential. Specifically,
with back analysis of the classical trajectories, we reveal the ionization time
and the OBI geometry of the sequentially released electrons, disentangling the
mechanisms behind the tilted angle of the band structures. These results
indicate that the classical treatment can describe the strong-field multiple
ionization processes of alkali atoms
Wholeâbrain microcirculation detection after ischemic stroke based on sweptâsource optical coherence tomography
The occurrence and development of ischemic stroke are closely related to cerebral blood flow. Realâtime monitoring of cerebral perfusion level is very useful for understanding the mechanisms of the disease. A wide field of view (FOV) is conducive to capturing lesions and observing the progression of the disease. In this paper, we attempt to monitor the wholeâbrain microcirculation in middle cerebral artery occlusion (MCAO) rats over time using a wide FOV sweptâsource OCT (SSâOCT) system. A constrained image registration algorithm is used to remove motion artifacts that are prone to occur in a wide FOV angiography. During ischemia, cerebral perfusion levels in the left and right hemispheres, as well as in the whole brain were quantified and compared. Changes in the shape and location of blood vessels were also recorded. The results showed that the trend in cerebral perfusion levels of both hemispheres was highly consistent during MCAO, and the position of the blood vessels varied over time. This work will provide new insights of ischemic stroke and is helpful to assess the effectiveness of potential treatment strategies.En face maximum intensity projections (MIP) of the wholeâbrain vascular networks obtained by wide field of view (FOV) sweptâsource optical coherence tomography (SSâOCT) system.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151895/1/jbio201900122_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151895/2/jbio201900122.pd
Whole File Chunk Based Deduplication Using Reinforcement Learning
Deduplication is the process of removing replicated data content from storage facilities like online databases, cloud datastore, local file systems, etc., which is commonly performed as part of data preprocessing to eliminate redundant data that requires unnecessary storage spaces and computing power. Deduplication is even more specifically essential for file backup systems since duplicated files will presumably consume more storage space, especially with a short backup period like daily [8]. A common technique in this field involves splitting files into chunks whose hashes can be compared using data structures or techniques like clustering. In this project we explore the possibility of performing such file chunk deduplication leveraging an innovative reinforcement learning approach to achieve a high deduplication ratio. We name the proposed system SegDup. It achieves 13% higher deduplication ratio than a state- of-the art deduplication algorithm named Extreme Binning
The impact of social capital-based game rewards on player loyalty in online gaming
In today's digital age, online games have attracted a large number of players from all walks of life due to their rich social elements. Rewards play a crucial role in keeping players engaged. This study examines the impact of social capital-based game rewards on player loyalty and aims to reveal how these reward mechanisms enhance player engagement and satisfaction through social interaction and social status. The research methods included questionnaire survey and interview. Direct feedback from players was collected through questionnaires, and then participants were screened for indepth interviews to gather personalized information. Based on the interview data, different types of social capital-based game rewards for player loyalty were evaluated. This study provides some suggestions for game developers to design social capital-based game rewards. At the same time, it also provides a direction for future study