3,680 research outputs found
The Xp10 bacteriophage protein P7 inhibits transcription by the major and major variant forms of the host RNA polymerase via a common mechanism
The σ factor is a functionally obligatory subunit of the bacterial transcription machinery, the RNA polymerase. Bacteriophage-encoded small proteins that either modulate or inhibit the bacterial RNAP to allow the temporal regulation of bacteriophage gene expression often target the activity of the major bacterial σ factor, σ70. Previously, we showed that during Xanthomonas oryzae phage Xp10 infection, the phage protein P7 inhibits the host RNAP by preventing the productive engagement with the promoter and simultaneously displaces the σ70 factor from the RNAP. In this study, we demonstrate that P7 also inhibits the productive engagement of the bacterial RNAP containing the major variant bacterial σ factor, σ54, with its cognate promoter. The results suggest for the first time that the major variant form of the host RNAP can also be targeted by bacteriophage-encoded transcription regulatory proteins. Since the major and major variant σ factor interacting surfaces in the RNAP substantially overlap, but different regions of σ70 and σ54 are used for binding to the RNAP, our results further underscore the importance of the σ–RNAP interface in bacterial RNAP function and regulation and potentially for intervention by antibacterials
Search Interfaces for Mathematicians
Access to mathematical knowledge has changed dramatically in recent years,
therefore changing mathematical search practices. Our aim with this study is to
scrutinize professional mathematicians' search behavior. With this
understanding we want to be able to reason why mathematicians use which tool
for what search problem in what phase of the search process. To gain these
insights we conducted 24 repertory grid interviews with mathematically inclined
people (ranging from senior professional mathematicians to non-mathematicians).
From the interview data we elicited patterns for the user group
"mathematicians" that can be applied when understanding design issues or
creating new designs for mathematical search interfaces.Comment: conference article "CICM'14: International Conference on Computer
Mathematics 2014", DML-Track: Digital Math Libraries 17 page
PT-Symmetry Quantum Electrodynamics--PTQED
The construction of -symmetric quantum electrodynamics is
reviewed. In particular, the massless version of the theory in 1+1 dimensions
(the Schwinger model) is solved. Difficulties with unitarity of the -matrix
are discussed.Comment: 11 pages, 1 figure, contributed to Proceedings of 6th International
Workshop on Pseudo-Hermitian Hamiltonians in Quantum Physic
Enhancement of low-mass dileptons in heavy-ion collisions
Using a relativistic transport model for the expansion stage of S+Au
collisions at 200 GeV/nucleon, we show that the recently observed enhancement
of low-mass dileptons by the CERES collaboration can be explained by the
decrease of vector meson masses in hot and dense hadronic matter.Comment: 12 pages, RevTeX, 3 figures available from [email protected]
Antikaon Production and Medium Effects in Heavy Ion Collisions at AGS
Antikaon production from heavy ion collisions at energies available from the
Alternating Gradient Synchrotron (AGS) at the Brookhaven National Laboratory is
studied in a relativistic transport (ART) model. We include contributions from
the baryon-baryon, meson-baryon, and meson-meson interactions. The final-state
interaction of antikaons via both absorption and elastic scattering by nucleons
and pions are also considered. To compare with presently available or future
experimental data, we have calculated the antikaon rapidity and transverse
momentum distributions as well as its collective flow. Medium effects on these
observables due to mean field potentials have also been investigated. It is
found that the ratio of antikaon transverse momentum spectrum to that of kaon
and their transverse flow are most sensitive to the in-medium properties of
kaons and antikaons.Comment: 19 pages, 13 figure
Sodium dependent inositol transport in HL60 cells is not related to Na+/K+, ATPase activity
AbstractIn HL60 cells, inositol transport is sodium-dependent but functionally independent of Na+/K+ ATPase activity. This observation has implications for the currently proposed theory for the development of diabetic complications
Charm meson scattering cross sections by pion and rho meson
Using the local flavor SU(4) gauge invariance in the limit of vanishing
vector meson masses, we extend our previous study of charm meson scattering
cross sections by pion and rho meson, which is based only on the
pseudoscalar-pseudoscalar-vector meson couplings, to include also contributions
from the couplings among three vector mesons and among four particles. We find
that diagrams with light meson exchanges usually dominate the cross sections.
For the processes considered previously, the additional interactions lead only
to diagrams involving charm meson exchanges and contact interactions, and the
cross sections for these processes are thus not much affected. Nevertheless,
these additional interactions introduce new processes with light meson
exchanges and increase significantly the total scattering cross sections of
charm mesons by pion and rho meson.Comment: 14 pages, revtex, 6 figures, added a figure on the effects of
on-shell divergence, final version to appear in Nucl. Phys.
Time-like T-duality algebra
When compactifying M- or type II string-theories on tori of indefinite
space-time signature, their low energy theories involve sigma models on
E_{n(n)}/H_n, where H_n is a not necessarily compact subgroup of E_{n(n)} whose
complexification is identical to the complexification of the maximal compact
subgroup of E_{n(n)}. We discuss how to compute the group H_n. For finite
dimensional E_{n(n)}, a formula derived from the theory of real forms of E_n
algebra's gives the possible groups immediately. A few groups that have not
appeared in the literature are found. For n=9,10,11 we compute and describe the
relevant real forms of E_n and H_n. A given H_n can correspond to multiple
signatures for the compact torus. We compute the groups H_n for all
compactifications of M-, M*-, and M'-theories, and type II-, II*- and
II'-theories on tori of arbitrary signature, and collect them in tables that
outline the dualities between them. In an appendix we list cosets G/H, with G
split and H a subgroup of G, that are relevant to timelike toroidal
compactifications and oxidation of theories with enhanced symmetries.Comment: LaTeX, 37 pages, 1 eps-figure, uses JHEP.cls; v2. corrected typo's in
tables 16 and 17, minor changes to tex
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