2,819 research outputs found
La virginidad de MarÃa, razón teológica de su asunción al cielo, en los formularios de la liturgia visigótica
La maternidad divina de MarÃa, dogma proclamado en Éfeso. A propósito de un libro de Th. Camelot
MarÃa madre de Jesús y madre de la Iglesia en la perspectiva teológica de la liturgia visigótica
Strings at the Intermediate Scale, or is the Fermi Scale Dual to the Planck Scale?
We show that if the string scale is identifed with the intermediate scale,
GeV, then the notorious hierarchy,
, can be explained using only as small input parameters, where is the
compactification scale. This is possible for weakly-coupled Type-I open-string
vacua if the observed world is assumed to live in an N=1 supersymmetric 3-brane
sector coupled to a separate, hidden, 3-brane world which breaks supersymmetry,
because for such a model . We
discuss some of the phenomenological issues presented by such an
intermediate-scale string, showing that its benefits include:
(i) the possibility of logarithmic gauge-coupling unification of the SM
couplings at ;
(ii) a natural axionic solution to the strong-CP problem with a
phenomenologically-acceptable Peccei-Quinn scale;
(iii) experimentally-interesting neutrino masses, and more.Comment: 16 pages, LaTeX, no figure
Cell type-specific regulation of choline acetyltransferase gene expression - Role of the neuron-restrictive silencer element and cholinergic-specific enhancer
This study demonstrates the presence of positive and negative regulatory elements within a 2336-base pair-long region of the rat choline acetyltransferase (ChAT) gene promoter that cooperate to direct cell type-specific expression in cholinergic cells. A 21-base pair-long neuron-restrictive silencer element (NRSE) was identified in the proximal part of this region. This element was recognized by the neuron-restrictive silencer factor (NRSF), previously shown to regulate expression of other neuron-specific genes. The ChAT NRSE was inactive in both cholinergic and non-cholinergic neuronal cells, but repressed expression from a heterologous promoter in non-neuronal cells. Specific deletion of this element allowed ChAT gene promoter activity in non-neuronal cells, and overexpression of NRSF repressed ChAT gene promoter activity in cholinergic cells. The distal part of the ChAT gene promoter showed cholinergic-specific enhancing activity, which stimulated promoter activity in cholinergic cells, but was inactive in non-cholinergic neuronal and non-neuronal cells. This enhancer region suppressed the activity of the ChAT NRSE in cholinergic cells, even after NRSF overexpression. Thus, at least two kinds of regulatory elements cooperate to direct ChAT gene expression to cholinergic neurons, namely a neuron-restrictive silencer element and a cholinergic-specific enhancer
Codimension 4 singularities of reflectionally symmetryc planar vector fields
The paper deals with the topological classification of singularities of vector fields on the plane which are invariant under reflection with respect to a line. As it has been proved in previous papers, such a classification is necessary to determine the different topological types of singularities of vector fields on R3 whose linear part is invariant under rotations. To get the classification we use normal form theory and the blowing-up method
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