Search results for "symmetry"
showing 10 items of 3576 documents
Optical bullets and "rockets" in nonlinear dissipative systems and their transformations and interactions
2006
We demonstrate the existence of stable optical light bullets in nonlinear dissipative media for both cases of normal and anomalous chromatic dispersion. The prediction is based on direct numerical simulations of the (3+1)-dimensional complex cubic-quintic GinzburgLandau equation. We do not impose conditions of spherical or cylindrical symmetry. Regions of existence of stable bullets are determined in the parameter space. Beyond the domain of parameters where stable bullets are found, unstable bullets can be transformed into >rockets> i.e. bullets elongated in the temporal domain. A few examples of the interaction between two optical bullets are considered using spatial and temporal interact…
Symmetry breakings in a metal organic framework with a confined guest
2020
The MOF $[{\text{Fe(tvp)}}_{2}{(\text{NCS})}_{2}]\ifmmode\cdot\else\textperiodcentered\fi{}2\text{BzCHO}$ is demonstrated to undergo a complex sequence of phase transitions and spin-crossover behavior of its constitutive ${\text{Fe}}^{\text{II}}$ ions upon adsorption of benzaldehyde guest molecules. Our study, combining Raman and synchrotron x-ray diffraction measurements on a single crystal, reveals that the conversion from the pure high-spin to the pure low-spin phases implies a rich sequence of intermediate phases, with symmetry breaking forming at least three different space groups. These different symmetries involve spin-state ordering, ligand ordering, and guest ordering, interpreted …
Etude des effets collisionnels dans les molécules tétraédriques. Applications au méthane perturbé par l'argon
1996
This thesis is devoted to the study of relaxational and collisional line-broadening processes in the first vibrational polyads of tetrahedral molecules. In a first part, the particular internal dynamics of such molecules is discussed. The second chapter reviews the literature on phenomena induced by intermolecular interactions involving this type of molecules. More theoretical aspects are developed in the second part. The so-called tetrahedral tensorial formalism adapted to the construction of Hamiltonians and transition moments of tetrahedral molecules is described. Main features of the infrared line-shapes theories and of semi-classical line-broadening and line-shifting calculations are a…
Excitons in few-layer hexagonal boron nitride: Davydov splitting and surface localization
2018
Hexagonal boron nitride (hBN) has been attracting great attention because of its strong excitonic effects. Taking into account few-layer systems, we investigate theoretically the effects of the number of layers on quasiparticle energies, absorption spectra, and excitonic states, placing particular focus on the Davydov splitting of the lowest bound excitons. We describe how the inter-layer interaction as well as the variation in electronic screening as a function of layer number $N$ affects the electronic and optical properties. Using both \textit{ab initio} simulations and a tight-binding model for an effective Hamiltonian describing the excitons, we characterize in detail the symmetry of t…
A particular coordination structure of Indo-European flavour
2005
The article aims to account for the various, often unexpected positions of the conjunction in coordinated constructions of ancient Indo-European languages, among them Hittite, Ancient Greek, Latin and Vedic Sanskrit. The coordination possibilities of ancient Indo-European languages are derived from the binary branching hypotheses of Universal Grammar, with the result that not only seemingly idiosyncratic facts of a number of languages receive a principled explanation, but also a speculative hypothesis of Universal Grammar receives empirical support; ancient Indo-European languages realize possibilities that are derivable from the Munn-Kayne theory but have not been attested so far.
Gli interessi moratori usurari ma contra legem
2021
Il saggio muove dalla recente sentenza delle Sezioni unite della Corte di cassazione sull'inclusione degli interessi moratori nell'ambito di applicazione della fattispecie dell'usura in astratto. La risposta data dalle Sezioni unite è positiva ed essa va pienamente condivisa, perché gli interessi moratori rientrano tra i costi dei finanziamenti, ancorché eventuali. Gli argomenti a sostegno di questa conclusione sono però totalmente errate e essi destano allarme perché si presentano chiaramente contra legem. The essay starts from the recent judgment of the Sezioni unite of the Court of Cassation on the inclusion of interests for non performance within the scope of the figure of usury so call…
La via errata delle Sezioni Unite al corretto riconoscimento della rilevanza usuraria degli interessi moratori
2021
Il saggio muove dalla recente sentenza delle Sezioni unite della Corte di cassazione sull'inclusione degli interessi moratori nell'ambito di applicazione della fattispecie dell'usura in astratto. La risposta data dalle Sezioni unite è positiva ed essa va pienamente condivisa, perché gli interessi moratori rientrano tra i costi dei finanziamenti, ancorché eventuali. Gli argomenti a sostegno di questa conclusione sono però totalmente errate e essi destano allarme perché si presentano chiaramente contra legem. The essay starts from the recent judgment of the Sezioni unite of the Court of Cassation on the inclusion of interests for non performance within the scope of the figure of usury so call…
Le Sezioni Unite su usura e interessi moratori: il fine non giustifica i mezzi
2021
Il saggio muove dalla recente sentenza delle Sezioni unite della Corte di cassazione sull'inclusione degli interessi moratori nell'ambito di applicazione della fattispecie dell'usura in astratto. La risposta data dalle Sezioni unite è positiva ed essa va pienamente condivisa. Gli argomenti a sostegno di questa conclusione sono però totalmente errate e essi destano allarme perché si presentano chiaramente contra legem. The essay starts from the recent judgment of the Sezioni unite of the Court of Cassation on the inclusion of interests for non performance within the scope of the figure of usury so called in the abstract. The answer given by the Sezioni unite is positive and it must be fully …
Estimates for Divergence Velocities of Axially Moving Orthotropic Thin Plates
2014
Some models for axially moving orthotropic thin plates are investigated analytically via methods of complex analysis to derive estimates for critical plate velocities. Linearised Kirchhoff plate theory is used, and the energy forms of steady-state models are considered with homogeneous and inhomogeneous tension profiles in the cross direction of the plate. With the help of the energy forms, some limits for the divergence velocity of the plate are found analytically. In numerical examples, the derived lower limits for the divergence velocity are analysed for plates with small flexural rigidity. peerReviewed
New high-sensitivity searches for neutrons converting into antineutrons and/or sterile neutrons at the HIBEAM/NNBAR experiment at the European Spalla…
2021
Abstract The violation of baryon number, B , is an essential ingredient for the preferential creation of matter over antimatter needed to account for the observed baryon asymmetry in the Universe. However, such a process has yet to be experimentally observed. The HIBEAM/NNBAR program is a proposed two-stage experiment at the European Spallation Source to search for baryon number violation. The program will include high-sensitivity searches for processes that violate baryon number by one or two units: free neutron–antineutron oscillation ( n → n ̄ ) via mixing, neutron–antineutron oscillation via regeneration from a sterile neutron state ( n → [ n ′ , n ̄ ′ ] → n ̄ ), and neutron disappearan…