Second gradient electromagnetostatics: electric point charge, electrostatic and magnetostatic dipoles

In this paper, we study the theory of second gradient electromagnetostatics as the static version of second gradient electrodynamics. The theory of second gradient electrodynamics is a linear generalization of higher order of classical Maxwell electrodynamics whose Lagrangian is both Lorentz and U(1)-gauge invariant. Second gradient electromagnetostatics is a gradient field theory with up to second-order derivatives of the electromagnetic field strengths in the Lagrangian. Moreover, it possesses a weak nonlocality in space and gives a regularization based on higher-order partial differential equations. From the group theoretical point of view, in second gradient electromagnetostatics the (isotropic) constitutive relations involve an invariant scalar differential operator of fourth order in addition to scalar constitutive parameters. We investigate the classical static problems of an electric point charge, and electric and magnetic dipoles in the framework of second gradient electromagnetostatics, and we show that all the electromagnetic fields (potential, field strength, interaction energy, interaction force) are singularity-free unlike the corresponding solutions in the classical Maxwell electromagnetism as well as in the Bopp-Podolsky theory. The theory of second gradient electromagnetostatics delivers a singularity-free electromagnetic field theory with weak spatial nonlocality.Comment: 32 pages, 7 figure

Evaluation of an adaptive hybrid tongue-brain control framework by individuals with amyotrophic lateral sclerosis

Preprint submitted to IOP Journal of Neural Engineering Objective. Individuals with Amyotrophic lateral sclerosis (ALS) progressively lose muscle functionality and therefore experience both an increased need for assistive robot technologies and a reduced ability to control such robots. While these individuals may use high-performing control systems, such as tongue control, at the beginning of their disease progression, they will eventually be restricted to a lower-performing control system, such as brain control. However, an adaptive multimodal control interface framework consisting of combinations of tongue control and noninvasive brain control can utilize the residual tongue functionality to optimize the control performance throughout the disease progression. Approach. To investigate this concept, a new adaptive tongue-brain multimodal control framework for manual and continuous control of a 7-degree-of-freedom robot arm is developed, based on a prior validation study. The new framework focuses on improved visual feedback, as individuals with ALS specifically requested this in a previous validation study, and consists of four subsystems: the first uses full tongue control; the second and third use hybrid tongue and noninvasive brain control, with a decreasing need for tongue functionality; and the fourth uses noninvasive brain control only. The framework was evaluated with three participants with ALS. Main results. All participants were succesful with all subsystems. One user could no longer efficiently use the full tongue control interface but achieved good results with the third and fourth subsystems. The second participant achieved significantly better results with the subsystems that included some tongue control, thereby showing the advantage of including some tongue control. The third participant performed well with all subsystems showing the ideal performance progression between each subsystem. Moreover, all participants, including the two with good tongue control, chose a multimodal control interface as their favorite. Significance. The results indicate that individuals with ALS prefer interfaces that combine multiple control modalities. </p

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field