We introduce the concept of cyclic covers, which generalizes the classical notion of covers in strings. Given any string X , a factor W of X is called a cyclic cover if each position of X belongs to an occurrence of a cyclic shift of W in X . Two cyclic covers are distinct if one is not a cyclic shift of the other. The cyclic covers problem asks for all distinct cyclic covers of an input string X . We present an algorithm that solves the cyclic covers problem in O ( n log ⁡ n ) time, where n is the length of X . It is based on finding a well-structured set of standard occurrences of a constant number of factors of a cyclic cover candidate W , computing the regions of X covered by cyclic shifts of W , extending those factors, and taking the union of the results. • We introduce the cyclic cover problem. • Two cyclic covers are distinct if one is not a cyclic shift of the other. • The cyclic cover problem requires finding all distinct cyclic covers of X . • We show that for a string of length n, the cyclic cover problem can be solved in O ( n log ⁡ n ) time.

A degenerate symbol over an alphabet Σ is a non-empty subset of Σ, and a sequence of such symbols is a degenerate string. We investigate the exact computation of maximal degenerate palindromes with gaps and mismatches. We present an algorithm which, given a degenerate string of length n and natural number parameters g and m, efficiently detects exact maximal palindromes with a gap size ≤g, and ≤m permitted mismatches. We show that it can be done in O(k|Σ|(k+log⁡|Σ|)+(k+g+m)n) time and O((g+m)n) space, where k represents an upper bound on the number of degenerate symbols contained in the string. Furthermore, we also show that the problem of factorisation a string into maximal degenerate palindromes with gaps and mismatches can also be done in O(k|Σ|(k+log⁡|Σ|)+(k+g+m)n) time and O((g+m)n) space. An inverted repeat is a specific type of palindrome which refers to a nucleotide sequence followed by its reverse complement. Our results can also be used to find maximal inverted repeated sequences with gaps and mismatches, where changing the structure of palindromes to inverted repeats does not affect the overall running time. Finally we demonstrate our algorithm on several strains of SARS-CoV-2, and quantify the number of inverted repeats found with ≤0,1,2 mismatches and ≤0,10,100 gap size.

Actuation means for soft robotic structures are manifold: despite actuation mechanisms such as tendon-driven manipulators or shape memory alloys, the majority of soft robotic actuators are fluidically actuated - either purely by positive or negative air pressure or by hydraulic actuation only. This paper presents the novel idea of employing hybrid fluidic - hydraulic and pneumatic - actuation for soft robotic systems. The concept and design of the hybrid actuation system as well as the fabrication of the soft actuator are presented: Polyvinyl Alcohol (PVA) foam is embedded inside a casted, reinforced silicone chamber. A hydraulic and pneumatic robotic syringe pump are connected to the base and top of the soft actuator. We found that a higher percentage of hydraulics resulted in a higher output force. Hydraulic actuation further is able to change displacements at a higher rate compared to pneumatic actuation. Changing between Hydraulic:Pneumatic (HP) ratios shows how stiffness properties of a soft actuator can be varied.