4,214 research outputs found
Genetic incorporation of D-Lysine into diketoreductase in Escherichia coli cells
D-Lysine has been genetically introduced into diketoreductase in E. coli cells by utilization of an orthogonal Ph tRNA /Lysyl-tRNA synthetase pair. This is the first report on the genetic incoporation of D-amino acids into proteins, which may be generally applicable to a wide variety of applications
Standard Model Mass Spectrum in Inflationary Universe
We work out the Standard Model (SM) mass spectrum during inflation with
quantum corrections, and explore its observable consequences in the squeezed
limit of non-Gaussianity. Both non-Higgs and Higgs inflation models are studied
in detail. We also illustrate how some inflationary loop diagrams can be
computed neatly by Wick-rotating the inflation background to Euclidean
signature and by dimensional regularization.Comment: 62 pages, JHEP accepted versio
Neutrino Signatures in Primordial Non-Gaussianities
We study the cosmological collider phenomenology of neutrinos in an effective
field theory. The mass spectrum of neutrinos and their characteristic
oscillatory signatures in the squeezed limit bispectrum are computed. Both
dS-covariant and slow-roll corrections are considered, so is the scenario of
electroweak symmetry breaking during inflation. Interestingly, we show that the
slow-roll background of the inflaton provides a chemical potential for the
neutrino production. The chemical potential greatly amplifies the oscillatory
signal and makes the signal observably large for heavy neutrinos without the
need of fine tuning.Comment: 31 pages, JHEP accepted versio
The disappearance of a narrow Mg II absorption system in quasar SDSS J165501.31+260517.4
In this letter, we present for the first time, the discovery of the
disappearance of a narrow Mg II absorption system
from the spectra of quasar SDSS J165501.31+260517.4 (). This
absorber is located at , and has a velocity offset of
with respect to the quasar. According to the velocity
offset and the line variability, this narrow Mg II
absorption system is likely intrinsic to the quasar. Since the corresponding UV
continuum emission and the absorption lines of another narrow Mg II
absorption system at are very
stable, we think that the disappearance of the absorption system is unlikely to
be caused by the change in ionization of absorption gas. Instead, it likely
arises from the motion of the absorption gas across the line of sight
On Factorizations of Upper Triangular Nonnegative Matrices of Order Three
Let T3(N0) denote the semigroup of 3×3 upper triangular matrices with nonnegative integral-valued entries. In this paper, we investigate factorizations of upper triangular nonnegative matrices of order three. Firstly, we characterize the atoms of the subsemigroup S of the matrices in T3(N0) with nonzero determinant and give some formulas. As a consequence, problems 4a and 4c presented by Baeth et al. (2011) are each half-answered for the case n=3. And then, we consider some factorization cases of matrix A in S with ρ(A)=1 and give formulas for the minimum factorization length of some special matrices in S
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