Acoustic Tunneling Study for Hexachiral Phononic Crystals Based on Dirac-Cone Dispersion Properties

Acoustic tunneling is an essential property for phononic crystals in a Dirac-cone state. By analyzing the linear dispersion relations for the accidental degeneracy of Bloch eigenstates, the influence of geometric parameters on opening the Dirac-cone state and the directional band gaps’ widths are investigated. For two-dimensional hexachiral phononic crystals, for example, the four-fold accidental degenerate Dirac point emerges at the center of the irreducible Brillouin zone (IBZ). The Dirac cone properties and the band structure inversion problem are discussed. Finally, to verify acoustic transmission properties near the double-Dirac-cone frequency region, the numerical calculation of the finite-width phononic crystal structure is carried out, and the acoustic transmission tunneling effect is proved. The results enrich and expand the manipulating method in the topological insulator problem for hexachiral phononic crystals.

Conformational variation in enzyme catalysis: A structural study on catalytic residues

Conformational variation in catalytic residues can be captured as alternative snapshots in enzyme crystal structures. Addressing the question of whether active site flexibility is an intrinsic and essential property of enzymes for catalysis, we present a comprehensive study on the 3D variation of active sites of 925 enzyme families, using explicit catalytic residue annotations from the Mechanism and Catalytic Site Atlas and structural data from the Protein Data Bank. Through weighted pairwise superposition of the functional atoms of active sites, we captured structural variability at single-residue level and examined the geometrical changes as ligands bind or as mutations occur. We demonstrate that catalytic centres of enzymes can be inherently rigid or flexible to various degrees according to the function they perform, and structural variability most often involves a subset of the catalytic residues, usually those not directly involved in the formation or cleavage of bonds. Moreover, data suggest that 2/3 of active sites are flexible, and in half of those, flexibility is only observed in the side chain. The goal of this work is to characterise our current knowledge of the extent of flexibility at the heart of catalysis and ultimately place our findings in the context of the evolution of catalysis as enzymes evolve new functions and bind different substrates.

The seeds of ethnic or tribalistic manifestations in Limpopo: The case of Makhado, Vuwani and Malamulele

This research article argued that the current conflicts between Vhavenda and Vatsonga, two decades and four years later after the first democratic elections for a new South Africa in 1994, are manifestations of the seeds that were sown by the Voortrekkers since their arrival around the Soutpansberg in the northern parts of South Africa in 1836. Makhado (Louis Trichardt), Vuwani and Malamulele have been embroiled in continuous arguments and counterarguments, advocacies and counter advocacies, including protests, and in some instances, destruction of the essential property. Before then, Vhavenda and Vatsonga used to live alongside each other and even together. In their traditional village settings, there was no discrimination based on language or ethnicity. Through review of early scholarly writings, oral resources garnered from elders and the author’s personal experience, a few episodes were highlighted, and the ramifications thereof were discussed.Contribution: This study also postulated that although the promotion of the tribes’ uniqueness was culturally significant, social cohesion and multiculturalism could have been sustained without institutionalising the segregation laws and demarcations, for these decisions have come back to haunt the present democratic South Africa’s ideals of nation building and social cohesion.

Functional Inequalities for Metric-Preserving Functions with Respect to Intrinsic Metrics of Hyperbolic Type

We obtain functional inequalities for functions which are metric-preserving with respect to one of the following intrinsic metrics in a canonical plane domain: hyperbolic metric or some restrictions of the triangular ratio metric, respectively, of a Barrlund metric. The subadditivity turns out to be an essential property, being possessed by every function that is metric-preserving with respect to the hyperbolic metric and also by the composition with some specific function of every function that is metric-preserving with respect to some restriction of the triangular ratio metric or of a Barrlund metric. We partially answer an open question, proving that the hyperbolic arctangent is metric-preserving with respect to the restrictions of the triangular ratio metric on the unit disk to radial segments and to circles centered at origin.

Visuo-Acoustic Stimulation’s Role in Synaptic Plasticity: A Review of the Literature

Brain plasticity is the capacity of cerebral neurons to change, structurally and functionally, in response to experiences. This is an essential property underlying the maturation of sensory functions, learning and memory processes, and brain repair in response to the occurrence of diseases and trauma. In this field, the visual system emerges as a paradigmatic research model, both for basic research studies and for translational investigations. The auditory system remains capable of reorganizing itself in response to different auditory stimulations or sensory organ modification. Acoustic biofeedback training can be an effective way to train patients with the central scotoma, who have poor fixation stability and poor visual acuity, in order to bring fixation on an eccentrical and healthy area of the retina: a pseudofovea. This review article is focused on the cellular and molecular mechanisms underlying retinal sensitivity changes and visual and auditory system plasticity.

Novel objects with causal schemas elicit selective responses in tool- and hand-selective lateral occipito-temporal cortex

Tool-selective lateral occipito-temporal cortex (LOTC) responds preferentially to images of tools (hammers, brushes) relative to non-tool objects (clocks, shoes). What drives these responses? Tools have elongated shapes and are more likely to have motor associations, but another essential property is that they exert causal effects on the environment. We tested whether LOTC would respond to novel objects associated with a tool-canonical schema in which their actions cause other events. To do so, we taught male and female human participants about novel objects embedded in animated event sequences, which varied in the temporal order of their events. Causer objects moved prior to the appearance of an environmental event (e.g., stars) while Reactor objects moved after an identical event; objects were matched on shape and motor association. During fMRI, participants viewed still images of these novel objects. We localized tool-selective LOTC and non-tool-selective parahippocampal cortex (PHC) by contrasting neural responses to images of familiar tools and non-tools. We found that LOTC responded more to Causers than Reactors; this effect was absent and weaker in right PHC. We also localized responses to images of hands, which elicit overlapping responses with tools. Across inferior temporal cortex, voxels’ tool and hand selectivity positively predicted a preferential response to Causers, and non-tool selectivity negatively so. We conclude that a causal schema typical of tools is sufficient to drive LOTC, and more generally, that preferential responses to domains across the temporal lobe may reflect the relational event structures typical of those domains.

Historicity as a Principle of Interpretation of Analytics of Human Being in Philosophy of M. Heidegger

Analysis of the state and possible options for the development of modern humanities gives the grounds to assert the growing importance of the idea of historicity in culture and philosophy during the 20th and early 21st centuries. In this regard, both the disclosure of the concept of historicity and the substantiation of the significance of the principle of historicity, both for the methodology of historical and philosophical knowledge and for humanitarian knowledge in general become relevant. The author of this article carries out historical and philosophical reconstruction of historical issues in the philosophy of M. Heidegger and reveals the process of converting the idea of historicity into the principle of German existentialism. It is concluded that with the help of historicity M. Heidegger was able to present his own version of phenomenology on an existential basis. Seeing an existential achievement in historicity, M. Heidegger understood by it the direction of existence to the source, tradition, on the basis of this, the intentionality of consciousness was revealed as an essential property of existence: the direction of man as a finite being to its source, which allowed the German philosopher to interpret historicity as a tradition, the existential source of man, and how the temporality of human existence. The author of this article concludes that in the philosophy of M. Heidegger historicity was transformed from an idea into a principle on the basis of which the German philosopher revealed not only the historicity of Dasein, building a fundamental ontology and hermeneutics of factuality, but also tried to solve the problem of the history of being, going beyond the existential philosophy.

Persona in spe. Anthropological and Theodical Aspects of Hope

I intend to reflect on three phenomena that are revealed in the personal experience of hope: (1) hope distinguishes a person from the natural context, but it does so through nature, i.e., based on desires rooted in human nature; (2) hope is not only inscribed in the existential situation of human being, but also expresses the very meaning of human transcendence: the person transcends themself, because they live the hope of fulfillment in the transcendent reality; hope is a foretaste of a higher, more perfect life; (3) hope is a person’s deeply experienced expectation of love, that is, of someone who loves. The above phenomena require a justification, which is the answer to the question “what is the reason for experiencing hope?”. Carrying out analyses on the basis of the modernized metaphysics of the person, I refer primarily to the concept of personal acts, to the concept of religiosity as an essential property of the person and to elements of the concept of love. The conclusions of these analyses indicate the necessity of accepting the real existence of the object of human hope, since personal life essentially goes beyond contingency, towards wholeness in the form of union with Someone who loves.

Electrically tuneable viscosity of Ionic Liquids

Viscosity is an essential property of lubricant, as it affects its capacity to form the lubricating film or to reduce friction and wear. One of highly desirable effect in tribology is to be able to control the viscosity of the lubricant externally in real-time without changing the lubricant. One of the possibilities is to apply an electric field to the lubricant. Since ionic liquids are solvent-free electrolytes, their properties can be usually altered by applying voltage. This preliminary research results reveal that viscosity of tested ionic liquid can be tuned by means of applying DC voltage.

Waste Glass Powder Reusability in High-Performance Concrete: Leaching Behavior and Ecotoxicity

This paper deals with the possibility of using different types of waste glass powder in high-performance concrete (HPC) mixtures as a fine fraction replacement. Subsequently, both fractions are used in this research in concrete as a substitute for fine sand and silica flour. To use waste glass in a basic building material such as concrete, it is necessary to verify the basic chemical properties of the selected waste materials. Apart from the basic chemical properties, its environmental impact also appears to be an essential property of waste materials in general. Therefore, the research is mainly focused on the leaching and ecotoxicity experiments on high-performance concrete. HPC mixtures are designed based on the results of the analyzed chemical properties and previous research performed by our research team. Ecotoxicity of these concretes is then verified using Czech standards to evaluate. The results showed a positive impact on the ecotoxic properties of waste glass when used in concrete. A new ecotoxicity classification of waste materials and concrete mixes containing waste materials is proposed as a result of this research and summarized in the conclusion of this paper.