Search results for "Intersection"

Affective (re)orientations in online discussions on the threat of violence posed by migrants

2020

Online discussions are rife with fear-evoking images and meaning making that highlight a perceived threat to the security of European nations and their inhabitants posed by migrants’ violence in the wake of increased immigration. This paper examines the role of emotions in shaping anti-immigration views as a response to the threat of violence attached to migrants in online conversations. Using a dataset of Finnish online discussion threads from 2015 to 2017 that were prompted by extensive media attention paid to various cases of violent crime in which migrants were suspects, we particularly analyse the affective dynamics of interpellation processes wherein discussants are invited to adopt a…

A rigidity theorem for Lagrangian deformations

2005

We consider deformations of singular Lagrangian varieties in symplectic manifolds. We prove that a Lagrangian deformation of a Lagrangian complete intersection is analytically rigid provided that this is the case infinitesimally. This result is given as a consequence of the coherence of the direct image sheaves of relative infinitesimal Lagrangian deformations.

The role of virtual work in Levi-Civita's parallel transport

2015

The current literature on history of science reports that Levi-Civita’s parallel transport was motivated by his attempt to provide the covariant derivative of the absolute differential calculus with a geometrical interpretation (For instance, see Scholz in The intersection of history and mathematics, Birkhauser, Basel, pp 203–230, 1994, Sect. 4). Levi-Civita’s memoir on the subject was explicitly aimed at simplifying the geometrical computation of the curvature of a Riemannian manifold. In the present paper, we wish to point out the possible role implicitly played by the principle of virtual work in Levi-Civita’s conceptual reasoning to formulate parallel transport.

Short hydrogen bonds enhance nonaromatic protein-related fluorescence

2021

Significance Intrinsic fluorescence of nonaromatic amino acids is a puzzling phenomenon with an enormous potential in biophotonic applications. The physical origins of this effect, however, remain elusive. Herein, we demonstrate how specific hydrogen bond networks can modulate fluorescence. We highlight the key role played by short hydrogen bonds, present in the protein structure, on the ensuing fluorescence. We provide detailed experimental and molecular evidence to explain these unusual nonaromatic optical properties. Our findings should benefit the design of novel optically active biomaterials for applications in biosensing and imaging.

On the relaxation mechanisms of 6-azauracil

2011

The nonadiabatic photochemistry of 6-azauracil has been studied by means of the CASPT2//CASSCF protocol and double-ζ plus polarization ANO basis sets. Minimum energy states, transition states, minimum energy paths, and surface intersections have been computed in order to obtain an accurate description of several potential energy hypersurfaces. It is concluded that, after absorption of ultraviolet radiation (248 nm), two main relaxation mechanisms may occur, via which the lowest (3)(ππ*) state can be populated. The first one takes place via a conical intersection involving the bright (1)(ππ*) and the lowest (1)(nπ*) states, ((1)ππ*/(1)nπ*)(CI), from which a low-energy singlet-triplet crossin…

Orbiting Orbitals: Visualization of Vi-Bronic Motion at a Conical Intersection

2013

The Jahn-Teller (JT) active unpaired electron of single metalloporphyrin radical anions is imaged through scanning tunneling microscopy. It is demonstrated that the electron is delocalized over the porphyrin macrocycle and its topographic image is determined by vibronic motion: the orbital of the electron adiabatically follows the zero-point pseudorotation of skeletal deformations. Transformation of the polar graphs of the observed images allows visualization of the adiabatic vibrational density to which the electron is coupled. The vibronic potential at the conical intersection is visualized and the half-integer angular momentum characteristic of the Berry phase is revealed in the radial f…

Excitation of Nucleobases from a Computational Perspective I: Reaction Paths

2013

The main intrinsic photochemical events in nucleobases can be described on theoretical grounds within the realm of non-adiabatic computational photochemistry. From a static standpoint, the photochemical reaction path approach (PRPA), through the computation of the respective minimum energy path (MEP), can be regarded as the most suitable strategy in order to explore the electronically excited isolated nucleobases. Unfortunately, the PRPA does not appear widely in the studies reported in the last decade. The main ultrafast decay observed experimentally for the gas-phase excited nucleobases is related to the computed barrierless MEPs from the bright excited state connecting the initial Franck…

On extremal intersection numbers of a block design

1982

K.N. Majumdar has shown that for a 2-(v, k, @l) design D there are three numbers @a, @t, and @S such that each intersection number of D is not greater than @S and not less than max{@a, @t}. In this paper we investigate designs having one of these 'extremal' intersection numbers. Quasisymmetric designs with at least one extremal intersection number are characterized. Furthermore, we show that a smooth design D having the intersection number @S or @a>0 is isomorphic to the system of points and hyperplanes of a finite projective space. Using this theorem, we can characterize all smooth strongly resolvable designs.

Packing dimension, intersection measures, and isometries

1997

Permutable products of supersoluble groups

2004

We investigate the structure of finite groups that are the mutually permutable product of two supersoluble groups. We show that the supersoluble residual is nilpotent and the Fitting quotient group is metabelian. These results are consequences of our main theorem, which states that such a product is supersoluble when the intersection of the two factors is core-free in the group.