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Taming the forest
No full textAn ongoing collaborative project between art and science, Taming the Forest (2022) was implemented by a team of students, artists and researchers charting an interdisciplinary project among bioeconomics, environmental history, policy and artistic practice. In this article, the project acts as a case study for researching the conflicting narratives of history and economics about biodiversity in general, and specifically about forests. It shows how different blends of methodologies in artistic-cum-scientific research can become relevant for both realms, opening new creative pathways and pedagogical registers while repeatedly returning to a specific forest’s microhistory. Moreover, the article stresses the need for a new sensibility and complex knowledge, moving beyond an objective study and becoming attentive to different dimensions of research and its outputs that emerge through the introduction of artistic thinking and methodologies. This kind of transdisciplinary approach becomes necessary in order to tackle the manifold large-scale problems such as the climate and biodiversity crises, which call for both acting decisively and transforming radically, above all with regard to how humans perceive, relate to and manage nature
Energy scale and resolution for anti-▫▫ jets with radius parameters R = 0.2 and 0.6 measured in proton-proton collisions at ▫▫ = 13 TeV with the ATLAS detector
No full textA crucial active site network of titratable residues guides catalysis and binding in human succinic semialdehyde dehydrogenase
No full textHuman succinic semialdehyde dehydrogenase is a mitochondrial enzyme fundamental in the neurotransmitter γ‐aminobutyric acid catabolism. It catalyzes the NAD+‐dependent oxidative degradation of its derivative, succinic semialdehyde, to succinic acid. Mutations in its gene lead to an inherited neurometabolic rare disease, succinic semialdehyde dehydrogenase deficiency, characterized by mental and developmental delay. Due to the poor characterization of this enzyme, we carried out evolutionary and kinetic investigations to contribute to its functional behavior, a prerequisite to interpreting pathogenic variants. An in silico analysis shows that succinic semialdehyde dehydrogenases belong to two families, one human‐like and the other of bacterial origin, differing in the oligomeric state and in a network of active site residues. This information is coupled to the biophysical–biochemical characterization of the human recombinant enzyme uncovering that (i) catalysis proceeds by an ordered bi–bi mechanism with NAD+ binding before the aldehyde that exerts a partial non‐competitive inhibition(ii) a stabilizing complex between the catalytic Cys340 and NAD+ is observed and interpreted as a protective mechanismand (iii) a concerted non‐covalent network assists the action of the catalytic residues Cys340 and Glu306. Through mutational analyses of Lys214, Glu306, Cys340, and Glu515 associated with pH studies, we showed that NAD+ binding is controlled by the dyad Lys214‐Glu515. Moreover, catalysis is assured by proton transfer exerted by the same dyad networked with the catalytic Glu306, involved in catalytic Cys340 deprotonation/reprotonation. The identification of this weak bond network essential for cofactor binding and catalysis represents a first step to tackling the molecular basis for its deficiency
Xylan degradation in the halotolerant bacterium Bacillus altitudinis relies on glycosidic hydrolases from families 11 and 30
No full textThe breakdown of xylan, a major hemicellulose component, involves multiple xylanases.Bacillus altitudinis SRL571, a halotolerant endophytic bacterium, utilizes glucuronoxylan and xylose as its sole carbon and energy sources. Genome analysis revealed two sequences encoding putative secreted xylanolytic glycoside hydrolases: one from family 11 (BaGH11) and another from family 30, subfamily 8 (BaGH30). These genes are located in two distinct operons involved in xylan and xylose catabolism, a genomic configuration unique to this strain. Both enzymes are salt-tolerant and act as endoxylanases: BaGH11 releases mainly short-chain xylooligosaccharides (e.g., xylobiose) while BaGH30 produces medium-chain xylooligosaccharides. BaGH11 and BaGH30 act synergistically to hydrolyze glucuronoxylan into xylose and xylobiose, which are subsequently imported into cells via putative sugar transporters. This study elucidates the biocatalytic basis of xylan degradation in a halotolerant bacterium and highlights the importance of complementary enzyme activities for effective biomass degradation in saline environment
General scheme using periodic and non-periodic functions for the chaotification of discrete-time systems
No full textThis work explores the use of a collection of periodic and non-periodic functions for the chaotification of discrete-time systems. Chaotification is the process of composing existing chaotic maps with a new function, in order to generate new families of maps with more complex behavior. The proposed method consists of scaling a seed function, adding offset boosting, and then composing it with a boundary function. An analytical formula is provided for the Lyapunov exponent of this new family of maps. Then, several wave-type boundary functions are considered, utilizing trigonometric and polynomial terms. These are tested on a collection of seed maps, like the sine and Renyi maps. The dynamical analysis performed reveals a collection of interesting phenomena, such as robust chaos. Overall, the proposed chaotification technique will enrich the behavior of its seed map
Application of a hyperbolic tangent chaotic map to random bit generation and image encryption
No full textIn this paper, a two-parameter one-dimensional chaotic map with hyperbolic tangent and two nested sinusoidal terms is proposed. The reported map exhibits rich chaotic behavior including such phenomena as the period-doubling route to chaos, crisis, and antimonotonicity appearing. The proposed map is applied for the pseudo-random bit generation and image encryption. To generate bit sequences, a simple rule is used. The generated sequences are verified using NIST statistical tests and cross-correlation analysis. Image encryption is performed using two rounds of shuffling of image pixels and XOR operation. We explicitly show the suitability of the proposed algorithm through histogram, correlation, and entropy analysis for the sample grayscale image
A novel chaotic system with application to secure communications
No full textIn this work, a novel three dimensional chaotic system with is proposed. The system has no linear terms and a line equilibrium, so it belongs to the category of systems with hidden attractors. The system\u27s dynamical behavior is analysed through its bifurcations diagrams and maximum Lyapunov exponent diagram. Then, the system is applied to the problem of secure communications using the Symmetric Chaos Shift Keying modulation method
Predictive control of a fractional order delayed chaotic system with circuit implementation
No full textThe time delay and fractional-order nonlinear systems have attracted great attention for the synchronization and security of information based on chaotic systems. In this paper, a new robust approach to control a fractional order delayed chaotic system is proposed, with the circuit implementation. Based on the theory of nonlinear predictive control and utilizing fundamental properties of fractional calculus, a new theorem to guarantee the convergence of the chaotic trajectory towards the equilibrium point of fractional order time-delay chaotic systems is developed. Numerical simulations are provided to verify the effectiveness of the design and a circuit implementation is performed to show the feasibility of the proposed approach
Modeling of discrete time auto-regressive systems with given forward and backward behavior
No full textWe study the behavior of discrete time AR-representations. A theorem is provided connecting the backward behavior of a system, due to its infinite elementary divisors, with the forward behavior of its dual system. We first use this result to construct a system satisfying a certain backward behavior. In addition to this, we propose a way to combine this result with previous ones to create an algorithm for computing a system satisfying a given forward and backward behavior