3,728 research outputs found
Topological mass in seven dimensions and dualities in four dimensions
The massive topologically and self dual theories en seven dimensions are
considered. The local duality between these theories is established and the
dimensional reduction lead to the different dualities for massive antisymmetric
fields in four dimensions.Comment: 7 page
A new case of autosomal recessive agammaglobulinaemia with impaired pre-B cell differentiation due to a large deletion of the IGH locus
Males with X-linked agammaglobulinaemia (XLA) due to mutations in the Bruton tyrosine kinase gene constitute the major group of congenital hypogammaglobulinaemia with absence of peripheral B cells. In these cases, blockages between the pro-B and pre-B cell stage in the bone marrow are found. The remaining male and female cases clinically similar to XLA represent a genotypically heterogeneous group of diseases. In these patients, various autosomal recessive disorders have been identified such as mutations affecting IGHM, CD79A, IGLL1 genes involved in the composition of the pre-B cell receptor (pre-BCR) or the BLNK gene implicated in pre-BCR signal transduction. In this paper, we report on a young female patient characterised by a severe non-XLA agammaglobulinaemia that represents a new case of Igmu defect. We show that the B cell blockage at the pro-B to pre-B cell transition is due to a large homologous deletion in the IGH locus encompassing the IGHM gene leading to the inability to form a functional pre-BCR. The deletion extends from the beginning of the diversity (D) region to the IGHG2 gene, with all JH segments and IGHM, IGHD, IGHG3 and IGHG1 genes missing.
CONCLUSION:
alteration in Igmu expression seems to be relatively frequent and could account for most of the reported cases of autosomal recessive agammaglobulinaemia
Deriving amino acid contact potentials from their frequencies of occurence in proteins: a lattice model study
The possibility of deriving the contact potentials between amino acids from
their frequencies of occurence in proteins is discussed in evolutionary terms.
This approach allows the use of traditional thermodynamics to describe such
frequencies and, consequently, to develop a strategy to include in the
calculations correlations due to the spatial proximity of the amino acids and
to their overall tendency of being conserved in proteins. Making use of a
lattice model to describe protein chains and defining a "true" potential, we
test these strategies by selecting a database of folding model sequences,
deriving the contact potentials from such sequences and comparing them with the
"true" potential. Taking into account correlations allows for a markedly better
prediction of the interaction potentials
Thermodynamics of protein folding: a random matrix formulation
The process of protein folding from an unfolded state to a biologically
active, folded conformation is governed by many parameters e.g the sequence of
amino acids, intermolecular interactions, the solvent, temperature and chaperon
molecules. Our study, based on random matrix modeling of the interactions,
shows however that the evolution of the statistical measures e.g Gibbs free
energy, heat capacity, entropy is single parametric. The information can
explain the selection of specific folding pathways from an infinite number of
possible ways as well as other folding characteristics observed in computer
simulation studies.Comment: 21 Pages, no figure
Bernstein-Sato functional equations, -filtrations, and multiplier ideals of direct summands
This paper investigates the existence and properties of a Bernstein-Sato
functional equation in nonregular settings. In particular, we construct
-modules in which such formal equations can be studied. The existence of the
Bernstein-Sato polynomial for a direct summand of a polynomial over a field is
proved in this context. It is observed that this polynomial can have zero as a
root, or even positive roots. Moreover, a theory of -filtrations is
introduced for nonregular rings, and the existence of these objects is
established for what we call differentially extensible summands. This family of
rings includes toric, determinantal, and other invariant rings. This new theory
is applied to the study of multiplier ideals and Hodge ideals of singular
varieties. Finally, we extend known relations among the objects of interest in
the smooth case to the setting of singular direct summands of polynomial rings.Comment: 42 pages. A new section on Hodge ideals is included. Comments welcom
Bernstein's inequality and holonomicity for certain singular rings
In this manuscript we prove the Bernstein inequality and develop the theory
of holonomic D-modules for rings of invariants of finite groups in
characteristic zero, and for strongly F-regular finitely generated graded
algebras with FFRT in prime characteristic. In each of these cases, the ring
itself, its localizations, and its local cohomology modules are holonomic. We
also show that holonomic D-modules, in this context, have finite length. We
obtain these results using a more general version of Bernstein filtrations.Comment: 34 pages. Comments welcom
Tuning the hydrogenation of CO2 to CH4 over mechano-chemically prepared palladium supported on ceria
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