428 research outputs found
Coalgebraic Trace Semantics for Buechi and Parity Automata
Despite its success in producing numerous general results on state-based dynamics, the theory of coalgebra has struggled to accommodate the Buechi acceptance condition---a basic notion in the
theory of automata for infinite words or trees. In this paper we present a clean answer to the question that builds on the "maximality" characterization of infinite traces (by Jacobs and Cirstea): the accepted language of a Buechi automaton is characterized by two commuting diagrams, one for a least homomorphism and the other for a greatest, much like in a system of (least and greatest) fixed-point equations. This characterization works uniformly for the nondeterministic branching and the probabilistic one; and for words and trees alike. We present our results in terms of the parity acceptance condition that generalizes Buechi\u27s
Parity Automata for Quantitative Linear Time Logics
We initiate a study of automata-based model checking for previously proposed quantitative linear time logics interpreted over coalgebras. Our results include: (i) an automata-theoretic characterisation of the semantics of these logics, based on a notion of extent of a quantitative parity automaton, (ii) a study of the expressive power of Buchi variants of such automata, with implications on the expressiveness of fragments of the logics considered, and (iii) a naive algorithm for computing extents, under additional assumptions on the domain of truth values
Effects of disorder on lattice Ginzburg-Landau model of d-wave superconductors and superfluids
We study the effects of quenched disorder on the two-dimensional d-wave
superconductors (SC's) at zero temperature by Monte-Carlo simulations. The
model is defined on the three-dimesional (3D) lattice and the SC pair field is
put on each spatial link as motivated in the resonating-valence-bond theory of
the high- SC's. For the nonrandom case, the model exhibits a
second-order phase transition to a SC state as density of charge carriers is
increased. It belongs to the universality class {\it different from} that of
the 3D XY model. Quenched disorders (impurities) are introduced both in the
hopping amplitude and the plaquette term of pair fields. Then the second-order
transition disappears at a critical concentration of quenched disorder,
. Implication of the results to cold atomic systems in optical
lattices is also discussed.Comment: 4 pages, 8 figure
Simple Display System of Mechanical Properties of Cells and Their Dispersion
The mechanical properties of cells are unique indicators of their states and functions. Though, it is difficult to recognize the degrees of mechanical properties, due to small size of the cell and broad distribution of the mechanical properties. Here, we developed a simple virtual reality system for presenting the mechanical properties of cells and their dispersion using a haptic device and a PC. This system simulates atomic force microscopy (AFM) nanoindentation experiments for floating cells in virtual environments. An operator can virtually position the AFM spherical probe over a round cell with the haptic handle on the PC monitor and feel the force interaction. The Young's modulus of mesenchymal stem cells and HEK293 cells in the floating state was measured by AFM. The distribution of the Young's modulus of these cells was broad, and the distribution complied with a log-normal pattern. To represent the mechanical properties together with the cell variance, we used log-normal distribution-dependent random number determined by the mode and variance values of the Young's modulus of these cells. The represented Young's modulus was determined for each touching event of the probe surface and the cell object, and the haptic device-generating force was calculated using a Hertz model corresponding to the indentation depth and the fixed Young's modulus value. Using this system, we can feel the mechanical properties and their dispersion in each cell type in real time. This system will help us not only recognize the degrees of mechanical properties of diverse cells but also share them with others
Device-free Indoor WLAN Localization with Distributed Antenna Placement Optimization and Spatially Localized Regression
Wireless sensing is a promising technology for future wireless communication
networks to realize various application services. Wireless local area network
(WLAN)-based localization approaches using channel state information (CSI) have
been investigated intensively. Further improvements in detection performance
will depend on selecting appropriate feature information and determining the
placements of distributed antenna elements. This paper presents a proposal of
an enhanced device-free WLAN-based localization scheme with beam-tracing based
antenna placement optimization and spatially localized regression, where
beam-forming weights (BFWs) are used as feature information for training
machine-learning (ML)-based models localized to partitioned areas. By this
scheme, the antenna placement at the access point (AP) is determined by solving
a combinational optimization problem with beam-tracing between AP and station
(STA) without knowing the CSI. Additionally, we propose the use of localized
regression to improve localization accuracy with low complexity, where
classification and regression based ML models are used for coarse and precise
estimations of the target position. We evaluate the proposed scheme effects on
localization performance in an indoor environment. Experiment results
demonstrate that the proposed antenna placement and localized regression scheme
improve the localization accuracy while reducing the required complexity for
both off-line training and on-line localization relative to other reference
schemes.Comment: This work has been submitted to the IEEE for possible publication.
Copyright may be transferred without notice, after which this version may no
longer be accessibl
Predictive value of heterogeneously enhanced MRI findings with CT evidence of calcification for severe motor deficits in spinal meningioma
OBJECTIVE: Spinal meningioma is mostly benign, but they can exhibit neurological deficit. The relationship between neurological impairment and its radiographic findings, including intratumor magnetic resonance imaging (MRI) gadolinium enhancement and calcification in computed tomography (CT) scan, has not been studied. The purpose of this study was to investigate the association of preoperative image findings with neurological status in spinal meningioma. METHODS: Patients histologically diagnosed with spinal meningioma (n = 24), with an average age of 65.4 years, were included. The patients were classified into 2 groups, the homogeneous and heterogeneous groups, based on the contrast-enhanced T1-weighted MRI findings. Further, baseline demographics (age, sex, presence of preoperative paralysis [manual muscle testing 3 or worse neurological deficit in upper and/or lower limbs], tumor level, tumor length, and tumor occupation ratio), histological findings (Ki-67 index and histological subtypes), and CT findings (presence of intratumor calcification and Hounsfield unit [HU] value) were examined. RESULTS: Preoperative paralysis was observed in 33.3% (8 of 24) of the patients. These patients exhibited frequent heterogeneous contrast-enhanced MRI findings than those without preoperative paralysis (57.1% vs. 14.3%, p = 0.040). Further, preoperative paralysis did not associate with tumor level, tumor length, tumor-occupied ratio, Ki-67 index, and histological subtypes. The heterogeneous group showed 100% intratumor calcification and higher maximum HU than the homogeneous group (1, 109.8 vs. 379.2, p = 0.001). CONCLUSION: The heterogeneous contrast-induced MRI findings in the spinal meningioma were significantly associated with preoperative neurological impairment. Moreover, the intratumor contrast-deficient region in the heterogeneously enhanced tumors reflected marked calcification. The tumor hardness due to calcification may be related to preoperative neurological deficit
Transplacental delivery of factor IX Fc-fusion protein ameliorates bleeding phenotype of newborn hemophilia B mice
Sakurai F., Iizuka S., Tsukamoto T., et al. Transplacental delivery of factor IX Fc-fusion protein ameliorates bleeding phenotype of newborn hemophilia B mice. Journal of Controlled Release 374, 415 (2024); https://doi.org/10.1016/j.jconrel.2024.08.022.Hemophilia B is an inherited hemorrhagic disorder characterized by a deficiency of blood coagulation factor IX (FIX) that results in abnormal blood coagulation. The blood coagulation is already evident in hemophiliacs at the fetal stage, and thus intracranial hemorrhage and other bleeding complications can occur at birth, leading to sequelae. Therefore, it is important to develop effective treatments for hemophiliacs in utero. In this study, in order to transplacentally deliver FIX from pregnant mice to their fetuses, an improved adenovirus (Ad) vector expressing human FIX fused with the IgG Fc domain (FIX Fc fusion protein), which plays a crucial role in neonatal Fc receptor (FcRn)-mediated transcytosis across the placenta, was intravenously administered to E13.5 pregnant mice. Significant levels of FIX Fc fusion protein were detected in 0-day-old newborn mice whose mothers were administered an Ad vector expressing FIX Fc fusion protein. Wild-type FIX overexpressed in the pregnant mice was not delivered to the fetuses. Plasma FIX levels in the newborn mice were relatively well correlated with those in their mothers, although transplacental delivery efficiencies of FIX Fc fusion protein were slightly reduced when the FIX Fc fusion protein was highly expressed in the mother mice. Plasma FIX levels in the newborn mice were about 3.6–6.4% of those in their mothers, Transplacental delivery of FIX Fc fusion protein to their fetuses successfully improved the blood clotting ability in the newborn mice
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In vivo experimental study of anterior cervical fusion using bioactive polyetheretherketone in a canine model
Background:
Polyetheretherketone (PEEK) is a widely accepted biomaterial, especially in the field of spinal surgery. However, PEEK is not able to directly integrate with bone tissue, due to its bioinertness. To overcome this drawback, various studies have described surface coating approaches aimed at increasing the bioactivity of PEEK surfaces. Among those, it has been shown that the recently developed sol-gel TiO2 coating could provide PEEK with the ability to bond with bone tissue in vivo without the use of a bone graft.
Objective:
This in vivo experimental study using a canine model determined the efficacy of bioactive TiO2-coated PEEK for anterior cervical fusion.
Methods:
Sol-gel–derived TiO2 coating, which involves sandblasting and acid treatment, was used to give PEEK bone-bonding ability. The cervical interbody spacer, which was designed to fit the disc space of a beagle, was fabricated using bioactive TiO2-coated PEEK. Both uncoated PEEK (control) and TiO2-coated PEEK spacers were implanted into the cervical intervertebral space of beagles (n = 5 for each type). After the 3-month survival period, interbody fusion success was evaluated based on μ-CT imaging, histology, and manual palpation analyses.
Results:
Manual palpation analyses indicated a 60% (3/5 cases) fusion (no gap between bone and implants) rate for the TiO2-coated PEEK group, indicating clear advantage over the 0% (0/5 cases) fusion rate for the uncoated PEEK group. The bony fusion rate of the TiO2-coated PEEK group was 40% according to μCT imaging; however, it was 0% of for the uncoated PEEK group. Additionally, the bone–implant contact ratio calculated using histomorphometry demonstrated a better contact ratio for the TiO2-coated PEEK group than for the uncoated PEEK group (mean, 32.6% vs 3.2%; p = 0.017).
Conclusions:
The TiO2-coated bioactive PEEK implant demonstrated better fusion rates and bone-bonding ability than did the uncoated PEEK implant in the canine anterior cervical fusion model. Bioactive PEEK, which has bone-bonding ability, could contribute to further improvements in clinical outcomes for spinal interbody fusion
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