Search results for " Algebra"
showing 10 items of 2082 documents
Population analysis of pair densities. A study on cyclic systems
2000
Abstract Pair population analysis seems a reliable method for evaluating atomic valency states and bond orders from the MO wavefunction of molecular systems. A test on some cyclic organic systems was performed. The results confirm the capability of the method to provide a correct description of the molecules in terms of simple VB approach.
Transferencia inter-dominios en resolución de problemas : una propuesta instruccional basada en el proceso de «traducción algebraica»
2009
Understanding a science and math word problem means constructing mental representations at different levels of abstraction. Secondary students have dificulties solving algebraic word problems due to the transition from the concrete representation to the mathematic representation. In order to facilitate the «algebraic translation» of the problems, we adapt a «rule to put a problem into equations» by Puig (1998) and insert it in an experimental methodology devoted to improving the inter-domain transfer in science. Results show the power of the instructional methodology to overcome most of the students’ dificulties, no matters their average academic performance.
Euler Characteristics of Moduli Spaces of Curves
2005
Let ${mathcal M}_g^n$ be the moduli space of n-pointed Riemann surfaces of genus g. Denote by ${\bar {\mathcal M}}_g^n$ the Deligne-Mumford compactification of ${mathcal M}_g^n$. In the present paper, we calculate the orbifold and the ordinary Euler characteristic of ${\bar {\mathcal M}}_g^n$ for any g and n such that n>2-2g.
Financial Stress and Basis in Energy Markets
2021
We investigate the relationship between energy commodities bases, inventory and financial stress from 1994 to 2018. We find that, from the 1998 Asian crisis the effect of financial stress on energy commodities bases gradually increased and from the 2008 crisis became positive, while the effect of inventory showed a gradual decline over time. The reactions of bases to changes in financial stress is nonlinear, as they are higher in the high financial stress periods. This is more profound in crude oil market than heating oil and natural gas. Moreover, the reactions of bases to the changes in inventory is nonlinear, as the reactions are lower when the inventory level is high confirming the theo…
Defining relations of minimal degree of the trace algebra of 3 X 3 matrices
2008
The trace algebra Cnd over a field of characteristic 0 is generated by all traces of products of d generic n × n matrices, n, d 2. Minimal sets of generators of Cnd are known for n = 2 and n = 3 for any d as well as for n = 4 and n = 5 and d = 2. The defining relations between the generators are found for n = 2 and any d and for n = 3, d = 2 only. Starting with the generating set of C3d given by Abeasis and Pittaluga in 1989, we have shown that the minimal degree of the set of defining relations of C3d is equal to 7 for any d 3. We have determined all relations of minimal degree. For d = 3 we have also found the defining relations of degree 8. The proofs are based on methods of representati…
Estimation of the mechanical properties of the eye through the study of its vibrational modes.
2017
Measuring the eye's mechanical properties in vivo and with minimally invasive techniques can be the key for individualized solutions to a number of eye pathologies. The development of such techniques largely relies on a computational modelling of the eyeball and, it optimally requires the synergic interplay between experimentation and numerical simulation. In Astrophysics and Geophysics the remote measurement of structural properties of the systems of their realm is performed on the basis of (helio-)seismic techniques. As a biomechanical system, the eyeball possesses normal vibrational modes encompassing rich information about its structure and mechanical properties. However, the integral a…
An unbounded family of log Calabi–Yau pairs
2016
We give an explicit example of log Calabi-Yau pairs that are log canonical and have a linearly decreasing Euler characteristic. This is constructed in terms of a degree two covering of a sequence of blow ups of three dimensional projective bundles over the Segre-Hirzebruch surfaces ${\mathbb F}_n$ for every positive integer $n$ big enough.
Enhancing values of roofs albedo for lowering cities’ air temperature and electric demand of buildings: a simple economic evaluation
2019
Abstract In cities vegetated roofs are becoming more popular because they can mitigate Urban Heat Island phenomena by decreasing the outdoor air temperature in summer. This decrease reduces the electric energy demand for climatization of buildings, which, in front of a milder climate, will recur less to mechanical tools for guaranteeing thermal comfort conditions to occupants. Cities can registered another indirect positive effect: the reduced cooling energy demand, limits the heat released by the climatization systems’ external unities toward the urban open spaces, thus lowering the outdoor air temperature. Therefore, the outdoor surface temperature of green, as well as cool roofs, can be …
A possible quantum motivation of the structure of quantum group
2011
We propose a (first) simple natural model of a non-finitely generated braided non-commutative Hopf Algebra, suggested by the elementary quantum mechanics.
Simple two-step synthesis of 2,4-disubstituted pyrroles and 3,5-disubstituted pyrrole-2-carbonitriles from enones
2014
The cyclocondensation of enones with aminoacetonitrile furnishes 3,4-dihydro-2H-pyrrole-2-carbonitriles which can be readily converted to 2,4-disubstituted pyrroles by microwave-induced dehydrocyanation. Alternatively, oxidation of the intermediates produces 3,5-disubstituted pyrrole-2-carbonitriles.