50,143 research outputs found
Comment on "On the importance of the free energy for elasticity under pressure"
Marcus et al. (Marcus P, Ma H and Qiu S L 2002 J. Phys.: Condens. Matter 14
L525) claim that thermodynamic properties of materials under pressure must be
computed using the Gibbs free energy , rather than the internal energy .
Marcus et al. state that ``The minima of , but not of , give the
equilibrium structure; the second derivatives of , but not of , with
respect to strains at the equilibrium structure give the equilibrium elastic
constants.'' Both statements are incorrect.Comment: Commen
Basis Independent Measures of R-parity Violation
We construct basis-independent expressions that measure the magnitude of
-parity breaking due to possible superpotential terms in the Minimal
Supersymmetric extension of the Standard Model, in the absence of soft
supersymmetry-breaking terms and spontaneous gauge symmetry breaking. We also
discuss briefly their application to a consistent treatment of cosmological
constraints on -parity violation.Comment: 13 pages, Late
An analysis of the practical DPG method
In this work we give a complete error analysis of the Discontinuous Petrov
Galerkin (DPG) method, accounting for all the approximations made in its
practical implementation. Specifically, we consider the DPG method that uses a
trial space consisting of polynomials of degree on each mesh element.
Earlier works showed that there is a "trial-to-test" operator , which when
applied to the trial space, defines a test space that guarantees stability. In
DPG formulations, this operator is local: it can be applied
element-by-element. However, an infinite dimensional problem on each mesh
element needed to be solved to apply . In practical computations, is
approximated using polynomials of some degree on each mesh element. We
show that this approximation maintains optimal convergence rates, provided that
, where is the space dimension (two or more), for the Laplace
equation. We also prove a similar result for the DPG method for linear
elasticity. Remarks on the conditioning of the stiffness matrix in DPG methods
are also included.Comment: Mathematics of Computation, 201
New records of wood inhabiting fungal species from Kondapalli reserved forest of Central Eastern Ghats, India
Wood inhabiting fungi that grow specifically on leaf litter, wood debris, humus rich soil of forest helps in biodegradation and increase soil fertility. The fruiting bodies of fungi were collected from partially dead forest trees, fallen wooden logs, leaf litter and decomposing humus rich soil of Kondapalli forest area, Central Eastern Ghats of India. Detailed macroscopic and microscopic study of collected fungal samples revealed the occurrence of wood inhabiting fungi belonging to 7 genera and 9 species; i.e. Geastrum triplex Jungh., Marasmius siccus (Schweinitz) Fries, M. fulvoferrugineus Gilliam, M. oreades (Bolt.: Fries) Fries Epicr. Lactarius piperatus (L.) Pers., Flammulina velutipes (Curtis) Singer, Artomyces microsporus (Qiu X. Wu & R. H. Petersen) Lickey, Hymenochaetopsis rigidula (Berk. & M. A. Curtis) S. H. He & Jiao Yang and Bjerkandera adusta (Willd: Fr.) Karst. For the first time, A. microsporus (Qiu X. Wu & R. H. Petersen) Lickey and H. rigidula (Berk. & M. A. Curtis) S. H. He & Jiao Yang., were reported from India. M. fulvoferrugineus Gilliam was reported second time from India. The wood inhabiting fungi were new records to Kondapalli forest area, Central Eastern Ghats of India
Norming Algebras and Automatic Complete Boundedness of Isomorphisms of Operator Algebras
We combine the notion of norming algebra introduced by Pop, Sinclair and
Smith with a result of Pisier to show that if A_1 and A_2 are operator
algebras, then any bounded epimorphism of A_1 onto A_2 is completely bounded
provided that A_2 contains a norming C*-subalgebra. We use this result to give
some insights into Kadison's Similarity Problem: we show that every faithful
bounded homomorphism of a C*-algebra on a Hilbert space has completely bounded
inverse, and show that a bounded representation of a C*-algebra is similar to a
*-representation precisely when the image operator algebra \lambda-norms
itself. We give two applications to isometric isomorphisms of certain operator
algebras. The first is an extension of a result of Davidson and Power on
isometric isomorphisms of CSL algebras. Secondly, we show that an isometric
isomorphism between subalgebras A_i of C*-diagonals (C_i,D_i) (i=1,2)
satisfying D_i \subseteq A_i \subseteq C_i extends uniquely to a *-isomorphism
of the C*-algebras generated by A_1 and A_2; this generalizes results of
Muhly-Qiu-Solel and Donsig-Pitts.Comment: 9 page
Comparing Cournot and Bertrand Equilibria in a Differentiated Duopoly with Product R&D
This paper compares Bertrand and Cournot equilibria in a differentiated duopoly with substitute goods and product R&D. I find that R&D expenditure, prices and firms� net profits are always higher under quantity competition than under price competition. Furthermore, output, consumer surplus and total welfare are higher in the Bertrand equilibrium than in the Cournot equilibrium if either R&D spillovers are weak or products are sufficiently differentiated. If R&D spillovers are strong and products are not too differentiated, then output, consumer surplus and total welfare are lower in the Bertrand case than in the Cournot case. Thus a key finding of the paper is that there are circumstances where quantity competition can be more beneficial than price competition both for consumers and for firms.
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