7,373 research outputs found
Classification of Static, Spherically Symmetric Solutions of the Einstein-Yang-Mills Theory with Positive Cosmological Constant
We give a complete classification of all static, spherically symmetric
solutions of the SU(2) Einstein-Yang-Mills theory with a positive cosmological
constant. Our classification proceeds in two steps. We first extend solutions
of the radial field equations to their maximal interval of existence. In a
second step we determine the Carter-Penrose diagrams of all 4-dimensional
space-times constructible from such radial pieces. Based on numerical studies
we sketch a complete phase space picture of all solutions with a regular
origin.Comment: 49 pages, 19 figures, submitted to Commun. Math. Phy
On Nonlinear -Models arizing in (Super-)Gravity
In a previous paper with Gibbons [CMP 120 (1987) 295] we derived a list of
three dimensional symmetric space -model obtained by dimensional
reduction of a class of four dimensional gravity theories with abelian gauge
fields and scalars. Here we give a detailed analysis of their group theoretical
structure leading to an abstract parametrization in terms of `triangular' group
elements. This allows for a uniform treatment of all these models. As an
interesting application we give a simple derivation of a `Quadratic Mass
Formula' for strictly stationary black holes.Comment: 33 pages, 1 tabl
Identification of a novel methyltransferase, Bmt2, responsible for the N-1-methyl-adenosine base modification of 25S rRNA in "Saccharomyces cerevisiae"
The 25S rRNA of yeast contains several base modifications in the functionally important regions. The enzymes responsible for most of these base modifications remained unknown. Recently, we identified Rrp8 as a methyltransferase involved in m1A645 modification of 25S rRNA. Here, we discovered a previously uncharacterized gene YBR141C to be responsible for second m1A2142 modification of helix 65 of 25S rRNA. The gene was identified by reversed phaseāHPLC screening of all deletion mutants of putative RNA methyltransferase and was confirmed by gene complementation and phenotypic characterization. Because of the function of its encoded protein, YBR141C was named BMT2 (base methyltransferase of 25S RNA). Helix 65 belongs to domain IV, which accounts for most of the intersubunit surface of the large subunit. The 3D structure prediction of Bmt2 supported it to be an Ado Met methyltransferase belonging to Rossmann fold superfamily. In addition, we demonstrated that the substitution of G180R in the S-adenosyl-l-methionineābinding motif drastically reduces the catalytic function of the protein in vivo. Furthermore, we analysed the significance of m1A2142 modification in ribosome synthesis and translation. Intriguingly, the loss of m1A2142 modification confers anisomycin and peroxide sensitivity to the cells. Our results underline the importance of RNA modifications in cellular physiology
First results in QCD with 2+1 light flavors using the fixed-point action
This is a progress report on 2+1 flavor simulation with the FP action on a
lattice with spatial size L=1.2fm. Since m_{ud} is quite small in our
simulation we are in the delta regime for the two light flavors where the low
lying excitations are described by a quantum mechanical rotator. From here we
extract the low energy constant F. We also measure the AWI mass and present
results on numerical issues like low-mode averaging and autocorrelation times.Comment: 7 pages, 6 figures, parallel talk at LATTICE 200
Transcriptional regulation of prostate kallikrein-like genes by androgen.
Using gene-specific synthetic oligonucleotides the
expression and regulation of kallikrein-like genes in
the human prostatic cancer cell line LNCaP were
studied. Prostate-specific antigen (PSA) and human
glandular kallikrein (hGK-1) together constitute a
subfamily of serine proteases exclusively produced
in the human prostate. RNA analysis revealed that
both genes are expressed in LNCaP cells with PSA
basal levels being 2-fold higher than hGK-1 levels.
Both mRNAs are induced over a period of 24 h in
the presence of 3.3 nM of the synthetic androgen
mibolerone. Stimulation of PSA RNA is about 5-
fold,whereas hGK-1 stimulation is less pronounced.
Nuclear run-on analysis revealed that androgen induction
of kallikrein-like genes in LNCaP cells is a
rapid event (c3 h) occurring at the level of transcription
initiation. Treatment of cells with cycloheximide
demonstrates that, while PSA/hGK-1 basal transcription
strictly depends on continuous protein synthesis,
transcriptional induction by androgen does
not. This suggests the direct involvement of the
androgen receptor in the induction process independent
of additional labile protein factors necessary
for kallikrein basal transcription. A binding motif
is present in the PSA and hGK-1 promoters, closely
resembling the consensus sequence for steroidresponsive
elements. The androgen antagonist cyproterone
acetate was also able to stimulate transcription
of kallikrein-like genes in LNCaP cells. In
contrast, androgen-dependent transcriptional
suppression of the protooncogene c-myc was
strongly counteracted by cyproterone acetate. Thus,
antiandrogens act differentially on androgen-regulated
prostate-specific (PSA, hGK-1) and growthrelated
(c-myc) gene expression in LNCaP cells
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