Cells can show not only spontaneous movement but also tactic responses to environmental signals. Since the former can be regarded as the basis to realize the latter, playing essential roles in ...various cellular functions, it is important to investigate spontaneous movement quantitatively at different physiological conditions in relation to a cell's physiological functions. For that purpose, we observed a series of spontaneous movements by Dictyostelium cells at different developmental periods by using a single cell tracking system. Using statistical analysis of these traced data, we found that cells showed complex dynamics with anomalous diffusion and that their velocity distribution had power-law tails in all conditions. Furthermore, as development proceeded, average velocity and persistency of the movement increased and as too did the exponential behavior in the velocity distribution. Based on these results, we succeeded in applying a generalized Langevin model to the experimental data. With this model, we discuss the relation of spontaneous cell movement to cellular physiological function and its relevance to behavioral strategies for cell survival.
This paper addresses the design problem of continuous-/discrete-time observer-based Gain-Scheduled Output Feedback (GSOF) controllers for Linear Parameter-Varying (LPV) systems, in which some of the ...state-space matrices are multi-affine with respect to parameters, with the simultaneous design of scaling matrices for multiple uncertainty blocks under the supposition that inexact scheduling parameters are available. In the design of GSOF controllers for practical systems in induced L2∕l2-norm control framework, the following features are to be incorporated; i) structured and easily-understandable controllers are preferable to enhance the practicality, ii) the scaling matrices related to multiple uncertainty blocks which represent various design specifications are also to be designed to reduce conservatism, and iii) one-shot design is preferable to prevent numerical problems in iterative algorithm. However, in general, neither the design problems of the structured controllers nor the simultaneous design of controllers and the performance scaling matrices are formulated in terms of Linear Matrix Inequalities (LMIs). Under the supposition that the uncertainties in the provided scheduling parameters are bounded (this supposition holds true for proportional uncertainties and for absolute uncertainties as well as for the mixed ones of them), we derive a new tractable one-shot multi-affine condition for our problem via dilated/extended LMI technique under some mild assumptions for LPV systems. A numerical example well illustrates the effectiveness of our method.
Middle meningeal artery embolization (MMAE) for chronic subdural hematoma (CSDH) is a novel, minimally invasive treatment. The indications and treatment practices for MMAE are variable and remain ...controversial. This study aimed to evaluate a strategy involving sequential MMAE after burr hole surgery for treating recurrent CSDH. We performed a retrospective analysis of data from consecutive patients who had undergone MMAE using liquid embolic agents within approximately 2 weeks after burr hole surgery for recurrent CSDH from September 2020 to March 2022. We analyzed patient characteristics, procedural details, CSDH recurrence after MMAE, surgical rescue, and complications. Six of the nine patients who underwent MMAE for CSDH recurrence were male, and the median age was 85 (range, 70-94) years. Five of the nine patients were being administered antithrombotic agents. The median duration between the burr hole surgery and MMAE procedure was 10 (range, 3-25) days. Anterior and posterior convexity branches were targeted for embolization using low-concentration N-butyl cyanoacrylate (NBCA), and the abnormal vascular networks with a cotton wool appearance disappeared after embolization in all cases. The NBCA distribution was observed by high-resolution computed tomography during the procedure; in three of nine cases, the NBCA penetrated not only the MMA but also the inner membrane. No recurrence, surgical rescue, or complications were observed in any patient during the median follow-up period of 3 months. As a minimally invasive treatment for recurrent CSDH, sequential MMAE after burr hole surgery may be a safe and effective option for preventing recurrence.
In this paper, we propose a new design method for Gain-Scheduled Output Feedback (GSOF) controllers for continuous-time Linear Parameter-Varying (LPV) systems via Parameter-Dependent Lyapunov ...Functions (PDLFs). The GSOF controllers depend solely on scheduling parameters. Although our method requires a line search to obtain suboptimal controllers, it produces practical GSOF controllers, being independent of the derivatives of scheduling parameters. Our method is proved to be no more conservative than conventional design methods via constant Lyapunov functions as well as particularly structured PDLFs.
This article considers the synthesis of feedback controllers for a class in which strong robust stability is required against sensing errors. The motivation dealing with this class arises from the ...stabilization problem of a cart-driven inverted pendulum by visual feedback control using a fisheye lens. While fisheye lenses guarantee a wide-angle of view, a large image distortion at off-center area is inevitable. Therefore this study first derives a geometric measurement model of a pendulum angle using a general fisheye lens model. A new design method for robust controllers for our problem is then proposed. Finally, a robust feedback controller that allows lens distortion is designed. The effectiveness of the controller based on the proposed model and the proposed design method is verified through numerical simulations and experiments.
It's a trap Suetsugu, Kenji; Sato, Masayuki
Frontiers in ecology and the environment,
20/May , Volume:
18, Issue:
4
Journal Article
Peer reviewed
Open access
The authors observed corpses of fungus gnats in Shizuoka, Japan, trapped at the bottom of the spathe (the large bract that surrounds the inflorescence) of the female Arisaema stenophyllum. In male ...plants, individual fungus gnats enter the upper part of the floral tube and then slide down the tube's inner wall, which is very slippery (preventing the gnats from climbing back out). The more the gnats struggle to escape, the greater the number of pollen grains attach to the gnats, which eventually find a small gap at the bottom of the spathe and leave. The escapees then enter a female spathe, where a more sinister fate awaits. Unlike male spathes, female spathes have no exit holes. The trapped insects continue to struggle inside the spathe searching an exit, but are trapped there until death. Thus, the fungus gnats are forced to pollinate female Arisaema flowers.
Phosphatidylinositol (Ptdlns) lipids have been identified as key signaling mediators for random cell migration as well as chemo-attractant-induced directional migration. However, how the Ptdlns ...lipids are organized spatiotemporally to regulate cellular motility and polarity remains to be clarified. Here, we found that self-organized waves of Ptdlns 3,4,5-trisphosphate Ptdlns(3,4,5)P₃ are generated spontaneously on the membrane of Dictyostelium cells in the absence of a chemoattractant. Characteristic oscillatory dynamics within the Ptdlns lipids signaling system were determined experimentally by observing the phenotypic variability of Ptdlns lipid waves in single cells, which exhibited characteristics of a relaxation oscillator. The enzymes phosphatase and tensin homolog (PTEN) and phosphoinostide-3-kinase (PI3K), which are regulators for Ptdlns lipid concentrations along the membrane, were essential for wave generation whereas functional actin cytoskeleton was not. Defects in these enzymes inhibited wave generation as well as actin-based polarization and cell migration. On the basis of these experimental results, we developed a reaction-diffusion model that reproduced the characteristic relaxation oscillation dynamics of the Ptdlns lipid system, illustrating that a self-organization mechanism provides the basis for the Ptdlns lipids signaling system to generate spontaneous spatiotemporal signals for random cell migration and that molecular noise derived from stochastic fluctuations within the signaling components gives rise to the variability of these spontaneous signals.
Background and Purpose
Endovascular trapping of the vertebral artery dissecting aneurysms (VADAs) carries a risk of medullary infarction due to the occlusion of the perforating arteries. We evaluated ...the detectability and anatomical variations of perforating arteries arising from the vertebral artery (VA) using three-dimensional DSA.
Methods
In 120 patients without VA lesions who underwent rotational vertebral arteriography, the anatomical configurations of perforating arteries from the VA were retrospectively evaluated on the bi-plane DSA and reconstructed images to reach the consensus between two experienced reviewers. The images were interpreted by focusing on the numbers and types of perforating arteries, the relationships between the number of perforators and the anatomy of the VA and its branches.
Results
Zero, 1, 2, 3, 4, and 6 perforators were detected in 2, 51, 56, 9, 1, and 1 patient, respectively (median of 2 perforators per VA). The 200 perforators were classified into 146 terminal and 54 longitudinal course types and into 32 ventral, 151 lateral, and 17 dorsolateral distribution types. All ventral type perforators were also terminal type. In contrast, the longitudinal type was seen in 28.5% of lateral types and in 65% of dorsolateral types. Regarding the difference in the origin of the posterior inferior cerebellar artery (PICA), non-PICA type VAs gave off larger number of perforators than the other types of VAs.
Conclusions
Non-PICA type VAs give off a significantly larger number of perforators than other types, indicating that the trapping of non-PICA type VAs is associated with a risk of ischemic complications.
We usually interpret a trapezoidal image on our retina as a slanted rectangle rather than a frontoparallel trapezoid, because we use a statistical assumption (i.e. rectangles are more common than ...trapezoids), called a 'prior', for recovering the 3D world from ambiguous 2D images. Here we report that the shape prior for recovering 3D slant can be updated differently depending on the slant axis orientation (horizontal vs. vertical). The participants were exposed to a variety of trapezoidal images surrounded by a stereoscopic reference plane. The perspective transformation of the images was interpreted as 2D shape, rather than 3D slant because the surrounding plane enhanced disparity. We found that, after continuous exposure to such images, the participants relied less on the shape information for recovering 3D slant, suggesting the update of priors via experience (i.e., rectangles are less common than trapezoids). Importantly, the learning effect was context (slant-axis) specific although partially transferred across contexts; the training with horizontal-axis slant reduced the reliance on perspective even in vertical-axis slant estimation but not vice versa. The results suggest that context-specific training is vital to update the prior for the horizontal-axis slant, whereas it is not required to update the prior for a vertical-axis slant.
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