Asymptotic structure with vanishing cosmological constant

This is the first of two papers [1] devoted to the asymptotic structure of space-time in the presence of a non-negative cosmological constant Λ. This first paper is concerned with the case of Λ = 0. Our approach is fully based on the tidal nature of the gravitational field and therefore on the ‘tidal energies’ built with the Weyl curvature. In particular, we use the (radiant) asymptotic supermomenta computed from the rescaled Weyl tensor at infinity to provide a novel characterisation of radiation escaping from, or entering into, the space-time. Our new criterion is easy to implement and shown to be fully equivalent to the classical one based on the news tensor. One of its virtues is that its formulation can be easily adapted to the case with Λ > 0 covered in the second paper. We derive the general energy-momentum-loss formulae including the matter terms and all factors associated to the choices of arbitrary foliation and of super- translation. We also revisit and present a full reformulation of the traditional peeling behaviour with a neat geometrical construction that leads, in particular, to an asymptotic alignment of the supermomenta in accordance with the radiation criterion.

Impact of geometrical construction on students’ creativity skills for sustainable development

The study investigated the perception of teachers and students on the impact of geometrical construction on students’ creativity skills for sustainable development in Edo State technical colleges using descriptive survey research design. The sample for comprised of 20 technical drawing teachers and 150 year II students randomly selected from the six technical colleges Edo State. A 20-item questionnaire was derived from literature reviewed was the instrument for data collection. The instrument was subjected to face validation by three experts. Cronbach Alpha method was used to establish the internal consistency of the instrument and a reliability index of 0.85 was obtained. Mean statistic was used to answer the research questions while the t-test was used to test the null hypothesis at .05 level of significance. The findings from the study indicated among others that geometrical construction enhances students’ diversity thinking; there was no significant difference between the perception of technical drawing teachers and students on the impact of geometrical construction on students’ creativity skills for sustainable development. Based on the findings of this study, it was recommended among others that: technical drawing teachers should utilize problem-solving instructional methods and strategies in their lessons in order to carry each student along, enhance students divergent thinking and creative skills, foster scientific and technological discoveries.

Geometrical framework for picture changing operators in the pure spinor formalism

It is well known in NSR string theory, that vertex operators can be constructed in various “pictures”. Recently this was discussed in the context of pure spinor formalism. NSR picture changing operators have an elegant super-geometrical interpretation. In this paper we provide a generalization of this super-geometrical construction, which is also applicable to the pure spinor formalism.

Geometrical Construction of Auxiliary Axes in an Ellingham Diagram

To facilitate the assessment of the oxide stability in H2-H2O or CO-CO2 atmospheres, auxiliary axes are constructed in the Ellingham diagram. Based on A. Ghosh’s approach, the geometrical interpretation of the diagram is proposed for the reaction 2X + O2 = 2Y, where X and Y could be originated from H2 and H2O or CO and CO2. Two cases are considered when oxygen partial pressures are lower and higher than one bar. By a geometrical method, it is proved that with an appropriate set-up of values relating to the auxiliary axes, the axes representing the ratio between the equilibrium partial pressure of hydrogen and that of water vapour, as well as the ratio between the equilibrium partial pressure of carbon monoxide and that of carbon dioxide, can be constructed. The geometrical method on the construction of axes using thermodynamic derivation is explained in the paper.

»Es ist so, weil ich es so mache.« Fichtes Methode der Konstruktion

In this paper I develop an account of Fichte’s conception of philosophical construction. Following the latter’s definition of philosophy as the ‘science of science’, philosophy is to be understood as a normative theory of what should qualify as science. In order to ground scientific knowledge-production as such, philosophy itself has to acquire a scientific method, through the application of which the constitution of scientific knowledge is secured. In systematic continuity to Kant’s account of geometrical construction, Fichte develops a philosophical method that exploits the special epistemic conditions of performativity. Construction is then defined as an experimental, self-reflexive performance that exemplifies consciousness. Throughout its acts of exemplification this reflexive kind of self-observation yields a particular type of experience, which ultimately satisfies the Science of Knowledge’s demand for certainty, that is intellectual intuition.Der vorliegende Aufsatz zeichnet Fichtes Verständnis der philosophischen Methode der Konstruktion nach. Folgend aus seiner Bestimmung der Philosophie als ‘Wissenschaft der Wissenschaft’ ergibt sich als deren Gegenstand das Wesen des Wissens selbst; Wissenschaftslehre als normative Wissenschaftstheorie bestimmt, was als wissenschaftlicher Bezug auf Welt gelten darf und stellt diesen zugleich sicher. Philosophie als Wissenschaft thematisiert also gerade die Natur jenes ausgezeichneten epistemischen Bezugs. Seine Sicherstellung erfolgt über eine Ausweisung der Wissenschaftlichkeit des philosophischen Verfahrens selbst, der Konstruktion. In systematischer Kontinuität zu Kants Beschreibung der geometrischen Konstruktion entwickelt Fichte eine philosophische Methode, welche sich die speziellen epistemischen Bedingungen des Selbst-Handelns zunutze macht. Konstruktion wird schließlich als experimenteller, selbstreflexiver Vollzug der Exemplifikation von Bewusstsein bestimmt. Dieses reflektierende Selbstbeobachten im Akt der Exemplifikation wiederum führt zu einer spezifischen Form von Erfahrung, welche ihrerseits der Wissenschaftslehre die geforderte Gewissheit verleiht: der intellektuellen Anschauung.

Tunable three-way topological energy-splitter

Strategically combining four structured domains creates the first ever three-way topological energy-splitter; remarkably, this is only possible using a square, or rectangular, lattice, and not the graphene-like structures more commonly used in valleytronics. To achieve this effect, the two mirror symmetries, present within all fully-symmetric square structures, are broken; this leads to two nondistinct interfaces upon which valley-Hall states reside. These interfaces are related to each other via the time-reversal operator and it is this subtlety that allows us to ignite the third outgoing lead. The geometrical construction of our structured medium allows for the three-way splitter to be adiabatically converted into a wave steerer around sharp bends. Due to the tunability of the energies directionality by geometry, our results have far-reaching implications for applications such as beam-splitters, switches and filters across wave physics.

Criminalistic Studies about Overcoming the Counteraction to the Crimes of Investigation

The subject of the research is the mechanism of overcoming the counteraction to the crimes of investigation and mechanism of marking formation, patterns of overcoming the counteraction to the crimes of investigation, their technological and criminalistic support, tactical and criminalistic support, methodological and criminalistic support of activities performed by law enforcement agencies and court. This is the first research to create a criminalistic teaching about overcoming the counteraction to the crimes of investigation and to develop an integral concept of such study as a combination of interrelated ideas and concepts. The methodology of the research includes general research methods (observation, description, comparison, experiment and modelling as sense-based research methods, analysis, synthesis, induction, deduction, analogy, hypothesis and abstraction as logical research methods, measurement, calculation and geometrical construction as mathematical methods). The author has also used special criminalistics methods (criminalistic identification, dactyloscopy, odorology, planning of investigative activities and organisation of investigation) as well as special methods from other branches of science such as physical, chemical and physical-chemical methods, anthropological and anthropometric methods, sociological methods and psychological methods. The scientific novelty of the research is caused by the fact that the author offers a new branch of criminalistics, criminalistic teaching about overcoming the counteraction to the crimes of investigation and development of the integral concept thereof based on rules and patterns of criminal procedure.