Dynamical system approach for edge detection using coupled FitzHugh–Nagumo neurons

The prospect of emulating the impressive computational capabilities of biological systems has led to considerable interest in the design of analog circuits that are potentially implementable in very large scale integration CMOS technology and are guided by biologically motivated models. For example, simple image processing tasks, such as the detection of edges in binary and grayscale images, have been performed by networks of FitzHugh-Nagumo-type neurons using the reaction-diffusion models. However, in these studies, the one-to-one mapping of image pixels to component neurons makes the size of the network a critical factor in any such implementation. In this paper, we develop a simplified version of the employed reaction-diffusion model in three steps. In the first step, we perform a detailed study to locate this threshold using continuous Lyapunov exponents from dynamical system theory. Furthermore, we render the diffusion in the system to be anisotropic, with the degree of anisotropy being set by the gradients of grayscale values in each image. The final step involves a simplification of the model that is achieved by eliminating the terms that couple the membrane potentials of adjacent neurons. We apply our technique to detect edges in data sets of artificially generated and real images, and we demonstrate that the performance is as good if not better than that of the previous methods without increasing the size of the network

Effect of Surfactants on Gas Holdup in Shear-Thinning Fluids

In this study, the gas holdup of bubble swarms in shear-thinning fluids was experimentally studied at superficial gas velocities ranging from 0.001 to 0.02 m·s−1. Carboxylmethyl cellulose (CMC) solutions of 0.2 wt%, 0.6 wt%, and 1.0 wt% with sodium dodecyl sulfate (SDS) as the surfactant were used as the power-law (liquid phase), and nitrogen was used as the gas phase. Effects of SDS concentration, rheological behavior, and physical properties of the liquid phase and superficial gas velocity on gas holdup were investigated. Results indicated that gas holdup increases with increasing superficial gas velocity and decreasing CMC concentration. Moreover, the addition of SDS in CMC solutions increased gas holdup, and the degree increased with the surfactant concentration. An empirical correlation was proposed for evaluating gas holdup as a function of liquid surface tension, density, effective viscosity, rheological property, superficial gas velocity, and geometric characteristics of bubble columns using the experimental data obtained for the different superficial gas velocities and CMC solution concentrations with different surfactant solutions. These proposed correlations reasonably fitted the experimental data obtained for gas holdup in this system

Motion characteristics of the vertebral segments with lumbar degenerative spondylolisthesis in elderly patients

Objective Although some studies have reported on the kinematics of the lumbar segments with degenerative spondylolisthesis (DS), few data have been reported on the in vivo 6 degree-of-freedom kinematics of different anatomical structures of the diseased levels under physiological loading conditions. This research is to study the in vivo motion characteristics of the lumbar vertebral segments with L4 DS during weight-bearing activities. Methods Nine asymptomatic volunteers (mean age 54.4) and 9 patients with L4 DS (mean age 73.4) were included. Vertebral kinematics was obtained using a combined MRI/CT and dual fluoroscopic imaging technique. During functional postures (supine, standing upright, flexion, and extension), disc heights, vertebral motion patterns and instability were compared between the two groups. Results Although anterior disc heights were smaller in the DS group than in the normal group, the differences were only significant at standing upright. Posterior disc heights were significantly smaller in DS group than in the normal group under all postures. Different vertebral motion patterns were observed in the DS group, especially in the left–right and cranial–caudal directions during flexion and extension of the body. However, the range of motions of the both groups were much less than the reported criteria of lumbar spinal instability. Conclusion The study showed that lumbar vertebra with DS has disordered motion patterns. DS did not necessary result in vertebral instability. A restabilization process may have occurred and surgical treatment should be planned accordingly.China Scholarship CouncilNational Institutes of Health (U.S.) (R21AR057 989

Gene expression program analysis of cancer-testis genes

Objective·To identify the gene expression program (GEP) of cancer-testis genes (CTGs) during spermatogenesis based on single-cell transcriptome data from the testis and investigate their association with the prognosis of cancer patients.Methods·Expression profiles of normal and tumor tissues were obtained from the GTEx and TCGA databases to screen CTGs. The GEP of CTGs during spermatogenesis was identified by applying the leiden clustering algorithm to testicular single-cell transcriptome data. DecoupleR was used to evaluate the activity levels of GEP and determine the cell types and stages of spermatogenesis where each GEP was active. Subsequently, DecoupleR was used to evaluate the activity levels of GEP in tumor tissues and analyze the correlation between GEP and cancer patient survival.Results·Based on the expression profiles of normal and tumor tissues from the GTEx and TCGA databases, 917 CTGs were identified. By using the expression patterns of CTGs in the testicular single-cell transcriptome data, seven GEPs were identified through the clustering algorithm. Activity level analysis revealed that GEP5 was active in the early stages of spermatogenesis, including spermatogonia stem cells, differentiating spermatogonia, and early primary spermatocytes. The distribution of GEP5-associated genes was predominantly found on the X chromosome. Additionally, survival analysis demonstrated a statistically significant negative correlation between GEP5 activity levels and patient survival in various tumors.Conclusion·During spermatogenesis, GEP5 is active in early stages, and its associated genes are primarily located on the X chromosome. In multiple tumor types, the activity level of GEP5 is closely related to patient prognosis

ABC block copolymer micelles driving the thermogelation:Scattering, imaging and spectroscopy

Thermoresponsive polymers have attracted much scientific attention due to their capacity for temperature-driven hydrogel formation. For biomedical applications, such as drug delivery, this transition should be tuned below body temperature to facilitate controlled and targeted drug release. We have recently developed a thermoresponsive polymer that forms gel at low concentrations (2 w/w%) in aqueous media and offers a cost-effective alternative to thermoresponsive systems currently being applied in clinics. This polymer is an ABC triblock terpolymer, where A, B, and C correspond to oligo(ethylene glycol) methyl ether methacrylate with average Mn 300 g mol−1 (OEGMA300), n-butyl methacrylate (BuMA), and di(ethylene glycol) methyl ether methacrylate (DEGMA). To investigate the self-assembly and the gelation mechanism in diluted solutions, we used small-angle neutron scattering (SANS) on 1 w/w% (below the gelation concentration) and 5 w/w% solutions (above the gelation concentration). As a comparison, we also investigated the solutions of the most studied thermoresponsive polymer, namely, Pluronic F127, an ABA triblock bipolymer made of ethylene glycol (A) and propylene glycol (B) blocks. SANS revealed that the in-house synthesised polymer forms elliptical cylinders, whose length increases significantly with temperature. In contrast, Pluronic F127 solutions form core-shell spherical micelles, which slightly elongate with temperature. Transmission electron microscopy images support the SANS findings, with tubular/worm structures being present. Variable-temperature circular dichroism (CD) and proton nuclear magnetic resonance (1H NMR) spectroscopy experiments reveal insights on the tacticity, structural changes, and molecular origin of the self-assembly

Clinical assessment of a low-cost, hand-held, smartphone-attached intraoral imaging probe for 5-aminolevulinic acid photodynamic therapy monitoring and guidance

SIGNIFICANCE: India has one of the highest rates of oral squamous cell carcinoma (OSCC) in the world, with an incidence of 15 per 100,000 and more than 70,000 deaths per year. The problem is exacerbated by a lack of medical infrastructure and routine screening, especially in rural areas. New technologies for oral cancer detection and timely treatment at the point of care are urgently needed. AIM: Our study aimed to use a hand-held smartphone-coupled intraoral imaging device, previously investigated for autofluorescence (auto-FL) diagnostics adapted here for treatment guidance and monitoring photodynamic therapy (PDT) using 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) fluorescence (FL). APPROACH: A total of 12 patients with 14 buccal mucosal lesions having moderately/well-differentiated micro-invasive OSCC lesions (1.65 at the time of treatment were associated with successful outcomes. CONCLUSION: These results indicate the utility of a low-cost, handheld intraoral imaging probe for image-guided PDT and treatment monitoring while also laying the groundwork for an integrated approach, combining cancer screening and treatment with the same hardware

An attractor network of weakly-coupled excitable neurons for general purpose of edge detection

The prospect of emulating the impressive computational capacities of biological systems has led to much interest in the design of analog circuits, potentially implementable in VLSI CMOS technology, that are guided by biologically motivated models. However, system design inevitably encounters the contrary constraints of size(or complexity) and computational power (or performance). From a high level design point of view, we believe that theoretical analysis of the model properties will undoubtedly benefit the implementation at a lower level. This thesis focuses on this simple aim to provide an extensive study of task-specific models based on dynamical systems in order to reduce model complexity or enhance the performance of algorithms.In many examples, it is the self-evolving dynamics of the model that allows the intrinsic parallel computations of algorithms, which are traditionally expressed by differential equations and systems. For instance, simple image processing tasks, such as the detection of edges in binary and grayscale images, have been performed by a reaction diffusion equation using the FitzHugh-Nagumo model as the reaction term in the previous work done by Kurata et al. (2008); Nomura et al. (2003, 2008, 2011b,a). Once the initial condition is correctly assigned according to a processed image, system states of this model will automatically evolve to the final result.From an application of view, the spatial distribution of system state can be regarded as a grid network with a proper discrete pattern; each network node becomes a FitzHugh-Nagumo type of neuron, while the diffusion term turns out to be the nearest couplings among them, where the coupling strength k is proportional to the original coefficient of diffusion D. So, one neuron (node) in the network deals with one pixel in the processed image. However, in previous study, this one-to-one mapping of image pixels to component neurons makes the size of the network a critical factor in any such implementation. The wrong edges are found due to the intrinsic mechanism of the algorithm when the diffused the processed image are used to pick out edges among the grayscale intensity levels and their most successful method solves this problem by a doubling of the size of the network.In the thesis, we propose two main improvements of the original algorithm in order for the smaller complexity and the better performance. We treat dynamics of the coupled system for the purpose of edge detection as a k-perturbation of the uncoupled one. Based on stability analysis of system state for both uncoupled and coupled cases, the system used for edge detection is identified as a Multiple Attractor type network and the final edge result corresponds to an attractor in high dimensional space. Hence, we conclude that the edge detection problem maps an image to an initial condition that is correctly located within the attraction domain of an expected attractor. For the first improvement, in order to get rid of the wrong edges, we provide a way of quantify the excitability of uncoupled neurons based on the Lyapunov exponents so that the boundary of attraction domain of the attractors can be well estimated. Moreover, an anisotropic diffused version of processed image is used for the further enhancement on the performance. For the second improvement, in order for diffusion of the processed image being accomplished by the hardware, we introduce a self-stopping mechanism to the original equation. Moreover, we link the basic design rules on system parameter settings to the fundamental theorem of WCNN (weakly coupled neural network) (Hoppensteadt and Izhikevich, 1997), which states that an uncoupled neuron must be near a threshold (bifurcation point) in order for rich dynamics to be presented in the coupled network. We apply our techniques to detect edges in data sets of artificially generated images (both noise-free and noise polluted) and real images, demonstrating performance that is as good if not better that the results of (Nomura et al., 2011b,a) with a smaller size of the network.<br/

Design and Implementation of an Optionally-Typed Functional Programming Language

This thesis describes the motivation, design, and implementation of L.B. Stanza, an optionally-typed functional programming language aimed at helping programmers tackle the complexity of architecting large programs and increasing their productivity across the entire software development life cycle. Its design objectives arose out of our own frustrations with writing software, and we built Stanza to be a practical general-purpose language that resolves the problems we encounter in our daily work.Stanza was designed to write programs of appreciable complexity; where development time is spent primarily on managing this complexity; and where better tools for managing complexity can significantly improve programmer productivity. In our experience with writing software, there are five primary activities that occupied the majority of our time: finding and fixing errors, coordinating multiple algorithms, architecting and maintaining a clean software infrastructure, minimizing and maintaining redundancies in code, and optimizing for performance. Stanza consists of five orthogonal subsystems to address each of the previous issues: the optional type system, the targetable coroutine system, the multimethod object system, the programmatic macro system, and the LoStanza sublanguage. Each subsystem is responsible for a separate facet of software development -- error detection, control flow and concurrency, architecture, syntactic abstraction, and low-level control -- and work in concert to form a small but expressive language.The optional type system allows programmers to transition freely between the dynamically-typed and statically-typed paradigms, and thus offers both productivity and flexibility in addition to early error detection capabilities. The targetable coroutine system allows for programmers to easily coordinate multiple algorithms, and also acts as a foundational control-flow operator. The multimethod object system is a novel class-less object system that unifies the functional programming with the object-oriented programming styles. The programmatic macro system allows for arbitrary syntactic abstractions in the style of Lisp while still retaining a natural and familiar syntax. Finally, the LoStanza sublanguage provides programmers both direct access to low-level hardware details as well as the ability to easily communicate and interoperate with high-level code.Stanza has been successfully applied to the development of a number of significant projects at U.C. Berkeley, including the development of a digital hardware design language, a just-in-time-compiled teaching language, as well as a full native-code optimizing compiler. By the later stages of the Stanza project, Stanza's productivity allowed for the optimizing compiler to be developed by a single student over the course of four months. This thesis describes the language design goals we have identified as being important for the class of programs we write, and how these goals are realized in the design of Stanza and its subsystems. Stanza's design is compared against that of other languages, and we point out the advantages and disadvantages of each. We then explain the overall implementation of the Stanza compiler and runtime system; share our personal experiences with teaching and programming in Stanza; and end with a summary of future work

Simulation of Unsteady Flows of Oil/Gas in the Ventless Bearing Chamber of an Aero-Engine

The unsteady motion behavior of oil/gas two-phase flow in a novel ventless bearing chamber has significant impacts on the lubrication and heat transfer efficiency of bearings due to the various advantages of lower pressure levels and weaker rotating airflow effects. In this paper, the unsteady motion behavior of oil/gas two-phase flow in a ventless aero-engine bearing chamber is investigated by three-dimensional numerical simulation through the volume of fluid (VOF) method, and the numerical method is verified using published experimental data. The flow characteristics of oil/gas two-phase in the secondary flow and three-dimensional flow are investigated. The results show the evolution of vortices and the transition of the driving mode in the unsteady motion of oil/gas two-phase flow, and a criterion for the shift of the driving mode at different rotor speeds is proposed. As the rotation speed increases, the variation trend of the velocity field and pressure field of oil/gas two-phase flow is consistent, and the accumulation region of oil becomes inconspicuous. The results indicate a reference for enhancing the performance of lubrication systems for aero-engines