646 research outputs found
Matrix methods for radial Schrödinger eigenproblems defined on a semi-infinite domain
No full textIn this paper, we discuss numerical approximation of the eigenvalues of the one-dimensional radial Schrödinger equation posed on a semi-infinite interval. The original problem is first transformed to one defined on a finite domain by applying suitable change of the independent variable. The eigenvalue problem for the resulting differential operator is then approximated by a generalized algebraic eigenvalue problem arising after discretization of the analytical problem by the matrix method based on high order finite difference schemes. Numerical experiments illustrate the performance of the approach
Biosistematica vegetale: Characterization of a natural hybrid between orchzs laxiflora lam and o morzo l (orchidaceae)
No full textMatrix methods for radial Schroedinger eigenproblems defined on a semi-infinite domain.
No full textIn this paper, we discuss numerical approximation of the eigenvalues of
the one-dimensional radial Schr ̈odinger equation posed on a semi-infinite
interval. The original problem is first transformed to one defined on a
finite domain by applying suitable change of the independent variable.
The eigenvalue problem for the resulting differential operator is then ap-
proximated by a generalized algebraic eigenvalue problem arising after
discretization of the analytical problem by the matrix method based on
high order finite difference schemes. Numerical experiments illustrate the
performance of the approach
Some applications of the Pascal matrix to the study of numerical methods for differential equations
No full textIn this paper we introduce and analyze some relations between the Pascal matrix and a new class of numerical methods for differential equations obtained generalizing the Adams methods. In particular, we shall prove that these methods are suitable for solving stiff problems since their absolute stability regions contain the negative half complex plane
A conserved "hydrophobic staple motif" plays a crucial role in the refolding of human glutathione transferase P1-1.
No full textThe specific (i, i+5) hydrophobic staple interaction involving a helix residue and a second residue located in the turn preceding the helix is a recurrent motif at the N terminus of alpha-helices. This motif is strictly conserved in the core of all soluble glutathione transferases (GSTs) as well as in other protein structures. Human GSTP1-1 variants mutated in amino acid Ile(149) and Tyr(154) of the hydrophobic staple motif of the alpha6-helix were analyzed. In particular, a double mutant cycle analysis has been performed to evaluate the role of the hydrophobic staple motif in the refolding process. The results show that this local interaction, by restricting the number of conformations of the alpha6-helix relative to the alpha1-helix, favors the formation of essential interdomain interactions and thereby accelerates the folding process. Thus, for the first time it is shown that the hydrophobic staple interaction has a role in the folding process of an intact protein. In P(i) class GSTs, Tyr(154) appears to be of particular structural importance, since it interacts with conserved residues Leu(21), Asp(24), and Gln(25) of the adjacent alpha1-helix which contributes to the active site. Human GSTP1-1 variants L21A and Y154F have also been analyzed in order to distinguish the role of interdomain interactions from that of the hydrophobic staple. The experimental results reported here suggest that the strict conservation of the hydrophobic staple motif reflects an evolutionary pressure for proteins to fold rapidl
Percorso di Oderisio da Benevento
No full textOderisio da Benevento is known for having signed the bronze doors of S. Giovanni Battista delle Monache at Capua (1122), the cathedral at Troia (1127) and the oratory of S. Bartolomeo at Benevento (1150-1151). There are also some con- vincing reasons to identify the same master with the male figure holding a pointed stylus along with the inscription ‘Oderisius’, who is depicted on a panel of another bronze door for the main portal of the cathedral at Troia (1119). Of all these signed works, only the two bronze doors at Troia survive today. Three doorknockers from the Treasury of the church of S. Cristina at Sepino, near Benevento, can be attributed to Oderisio for their stylistic consonance with the 1119 door. The main issue for the reconstruction of the artistic personality of Oderisio, who is clearly oriented towards the Romanesque style, con- sists in the higher inventiveness he showed in the reliefs of his earliest work at Troia compared to the rest of his catalogue.
As argued by Pietro Toesca, these differences urge to reconsider the role played by the Bene- ventan caster in the making of the 1119 door at Troia, where he is portrayed together with a mysterious figure, identified by the inscription as ‘Berardus’. The author of this article believes that Berardus, a name of German origins, was the designer and the caster of the most difficult and unusual elements of the door, as well as the mentor of a stylistic change in Oderisio. The often-misunderstood damascened figures attri- buted to the latter clearly testify to his interest for the art of Northern Europe
Are Two Binary Operators Necessary to Finitely Axiomatise Parallel Composition?
No full textBergstra and Klop have shown that bisimilarity has a finite equational axiomatisation over ACP/CCS extended with the binary left and communication merge operators. Moller proved that auxiliary operators are necessary to obtain a finite axiomatisation of bisimilarity over CCS, and Aceto et al. showed that this remains true when Hennessy’s merge is added to that language. These results raise the question of whether there is one auxiliary binary operator whose addition to CCS leads to a finite axiomatisation of bisimilarity. This study provides a negative answer to that question based on three reasonable assumptions
L'Exultet della Biblioteca Casanatense (Cas. 724 B I 13,3) e la scultura tra Puglia e Campania nella prima età normanna
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