Optimal Control of a Soft CyberOctopus Arm

In this paper, we use the optimal control methodology to control a flexible, elastic Cosserat rod. An inspiration comes from stereotypical movement patterns in octopus arms, which are observed in a variety of manipulation tasks, such as reaching or fetching. To help uncover the mechanisms underlying these observed morphologies, we outline an optimal control-based framework. A single octopus arm is modeled as a Hamiltonian control system, where the continuum mechanics of the arm is modeled after the Cosserat rod theory, and internal, distributed muscle forces and couples are considered as controls. First order necessary optimality conditions are derived for an optimal control problem formulated for this infinite dimensional system. Solutions to this problem are obtained numerically by an iterative forward-backward algorithm. The state and adjoint equations are solved in a dynamic simulation environment, setting the stage for studying a broader class of optimal control problems. Trajectories that minimize control effort are demonstrated and qualitatively compared with observed behaviors

Coexisting Innominate Vein Compression Syndrome and May-Thurner Syndrome

AbstractInnominate vein compression syndrome and May-Thurner syndrome (also called iliac vein compression syndrome) are venous compression syndromes caused by normal anatomic structures. Here, we present a case in which these two conditions were found in the same patient using multidetector row computed tomography. This case is significant for two reasons: (1) it is, to the best of our knowledge, the first case study in the literature to report coexisting innominate vein compression syndrome and May-Thurner syndrome; and (2) it shows that multidetector row computed tomography has powerful diagnostic ability for venous diseases

Controlling a CyberOctopus Soft Arm with Muscle-like Actuation

This paper presents an application of the energy shaping methodology to control a flexible, elastic Cosserat rod model of a single octopus arm. The novel contributions of this work are two-fold: (i) a control-oriented modeling of the anatomically realistic internal muscular architecture of an octopus arm; and (ii) the integration of these muscle models into the energy shaping control methodology. The control-oriented modeling takes inspiration in equal parts from theories of nonlinear elasticity and energy shaping control. By introducing a stored energy function for muscles, the difficulties associated with explicitly solving the matching conditions of the energy shaping methodology are avoided. The overall control design problem is posed as a bilevel optimization problem. Its solution is obtained through iterative algorithms. The methodology is numerically implemented and demonstrated in a full-scale dynamic simulation environment Elastica. Two bio-inspired numerical experiments involving the control of octopus arms are reported

The association between tyrosine kinase inhibitors and fatal arrhythmia in patients with non-small cell lung cancer in Taiwan

ObjectiveAs a standard therapy, tyrosine kinase inhibitors (TKIs) improved survival in patients with non-small cell lung cancer (NSCLC) and epidermal growth factor receptor (EGFR) mutation. However, treatment-related cardiotoxicity, particularly arrhythmia, cannot be ignored. With the prevalence of EGFR mutations in Asian populations, the risk of arrhythmia among patients with NSCLC remains unclear.MethodsUsing data from the Taiwanese National Health Insurance Research Database and National Cancer Registry, we identified patients with NSCLC from 2001 to 2014. Using Cox proportional hazards models, we analyzed outcomes of death and arrhythmia, including ventricular arrhythmia (VA), sudden cardiac death (SCD), and atrial fibrillation (AF). The follow-up duration was three years.ResultsIn total, 3876 patients with NSCLC treated with TKIs were matched to 3876 patients treated with platinum analogues. After adjusting for age, sex, comorbidities, and anticancer and cardiovascular therapies, patients receiving TKIs had a significantly lower risk of death (adjusted HR: 0.767; CI: 0.729–0.807, p < 0.001) than those receiving platinum analogues. Given that approximately 80% of the studied population reached the endpoint of mortality, we also adjusted for mortality as a competing risk. Notably, we observed significantly increased risks of both VA (adjusted sHR: 2.328; CI: 1.592–3.404, p < 0.001) and SCD (adjusted sHR: 1.316; CI: 1.041–1.663, p = 0.022) among TKI users compared with platinum analogue users. Conversely, the risk of AF was similar between the two groups. In the subgroup analysis, the increasing risk of VA/SCD persisted regardless of sex and most cardiovascular comorbidities.ConclusionsCollectively, we highlighted a higher risk of VA/SCD in TKI users than in patients receiving platinum analogues. Further research is needed to validate these findings

Development of Simple Sequence Repeats (SSR) Markers in Setaria italica (Poaceae) and Cross-Amplification in Related Species

Foxtail millet is one of the world’s oldest cultivated crops. It has been adopted as a model organism for providing a deeper understanding of plant biology. In this study, 45 simple sequence repeats (SSR) markers of Setaria italica were developed. These markers showing polymorphism were screened in 223 samples from 12 foxtail millet populations around Taiwan. The most common dinucleotide and trinucleotide repeat motifs are AC/TG (84.21%) and CAT (46.15%). The average number of alleles (Na), the average heterozygosities observed (Ho) and expected (He) are 3.73, 0.714, 0.587, respectively. In addition, 24 SSR markers had shown transferability to six related Poaceae species. These new markers provide tools for examining genetic relatedness among foxtail millet populations and other related species. It is suitable for germplasm management and protection in Poaceae

Nanoscale III-V Semiconductor Photodetectors for High-Speed Optical Communications

Nanophotonics involves the study of the behavior of light on nanometer scale. Modern nanoscale semiconductor photodetectors are important building blocks for high-speed optical communications. In this chapter, we review the state-of-the-art 2.5G, 10G, and 25G avalanche photodiodes (APDs) that are available in commercial applications. We discuss the key device parameters, including avalanche breakdown voltage, dark current, temperature dependence, bandwidth, and sensitivity. We also present reliability analysis on wear-out degradation and optical/electrical overload stress. We discuss the reliability challenges of nanoscale photodetectors associated with device miniaturization for the future. The reliability aspects in terms of high electric field, Joule heating, and geometry inhomogeneity are highlighted

Energy Shaping Control of a CyberOctopus Soft Arm

This paper entails application of the energy shaping methodology to control a flexible, elastic Cosserat rod model. Recent interest in such continuum models stems from applications in soft robotics, and from the growing recognition of the role of mechanics and embodiment in biological control strategies: octopuses are often regarded as iconic examples of this interplay. Here, the dynamics of the Cosserat rod, modeling a single octopus arm, are treated as a Hamiltonian system and the internal muscle actuators are modeled as distributed forces and couples. The proposed energy shaping control design procedure involves two steps: (1) a potential energy is designed such that its minimizer is the desired equilibrium configuration; (2) an energy shaping control law is implemented to reach the desired equilibrium. By interpreting the controlled Hamiltonian as a Lyapunov function, asymptotic stability of the equilibrium configuration is deduced. The energy shaping control law is shown to require only the deformations of the equilibrium configuration. A forward-backward algorithm is proposed to compute these deformations in an online iterative manner. The overall control design methodology is implemented and demonstrated in a dynamic simulation environment. Results of several bio-inspired numerical experiments involving the control of octopus arms are reported