617 research outputs found
Slowly rotating black hole solutions in Horndeski gravity
We study black hole solutions at first order in the Hartle-Thorne
slow-rotation approximation in Horndeski gravity theories. We derive the
equations of motion including also cases where the scalar depends linearly on
time. In the Hartle-Thorne formalism, all first-order rotational corrections
are described by a single frame-dragging function. We show that the
frame-dragging function is exactly the same as in general relativity for all
known black hole solutions in shift symmetric Horndeski theories, with the
exception of theories with a linear coupling to the Gauss-Bonnet invariant. Our
results extend previous no-hair theorems for a broad class of Horndeski gravity
theories.Comment: Fixed more typos found in proof. Matches version published in PR
Affleck-Dine leptogenesis via multiscalar evolution in a supersymmetric seesaw model
A leptogenesis scenario in a supersymmetric standard model extended with
introducing right-handed neutrinos is reconsidered. Lepton asymmetry is
produced in the condensate of a right-handed sneutrino via the Affleck-Dine
mechanism. The LH_u direction develops large value due to a negative effective
mass induced by the right-handed sneutrino condensate through the Yukawa
coupling of the right-handed neutrino, even if the minimum during the inflation
is fixed at the origin. The lepton asymmetry is nonperturbatively transfered to
the LH_u direction by this Yukawa coupling.Comment: 19 pages, 3 figures. Revised version for publication. The model was
modified to fix some problem
Diffusion and activation of n-type dopants in germanium
The diffusion and activation of -type impurities (P and As) implanted into
-type Ge(100) substrates were examined under various dose and annealing
conditions. The secondary ion mass spectrometry profiles of chemical
concentrations indicated the existence of a sufficiently high number of
impurities with increasing implanted doses. However, spreading resistance probe
profiles of electrical concentrations showed electrical concentration
saturation in spite of increasing doses and indicated poor activation of As
relative to P in Ge. The relationships between the chemical and electrical
concentrations of P in Ge and Si were calculated, taking into account the
effect of incomplete ionization. The results indicated that the activation of P
was almost the same in Ge and Si. The activation ratios obtained experimentally
were similar to the calculated values, implying insufficient degeneration of
Ge. The profiles of P in Ge substrates with and without damage generated by Ge
ion implantation were compared, and it was clarified that the damage that may
compensate the activated -type dopants has no relationship with the
activation of P in Ge.Comment: 6 pages, 4 figure
Vortices, Q-balls and Domain Walls on Dielectric M2-branes
We study BPS solitons in N=6 U(N) \times U(N) Chern-Simons-matter theory
deformed by an F-term mass. The F-term mass generically breaks N=6
supersymmetry down to N=2. At vacua, M2-branes are polarized into a fuzzy S^3
forming a spherical M5-brane with topology \mathbf{R}^{1,2} \times S^3. The
polarization is interpreted as Myers' dielectric effect caused by an
anti-self-dual 4-form flux T_4 in the eleven-dimensional supergravity. Assuming
a polarized M2-brane configuration, the model effectively reduces to the
well-known abelian Chern-Simons-Higgs model studied in detail by
Jackiw-Lee-Weinberg. We find that the potential for the fuzzy S^3 radius agrees
with the one calculated from the M5-brane point of view at large N. This
effective model admits not only BPS topological vortex and domain wall
solutions but also non-topological solitons that keep 1/4 of the manifest N=2
supersymmetry. We also comment on the reduction of our configuration to ten
dimensions.Comment: references added, minor modification
Curvature perturbation in multi-field inflation with non-minimal coupling
In this paper we discuss a multi-field model of inflation in which generally
all fields are non-minimally coupled to the Ricci scalar and have non-canonical
kinetic terms. The background evolution and first-order perturbations for the
model are evaluated in both the Jordan and Einstein frames, and the respective
curvature perturbations compared. We confirm that they are indeed not the same
- unlike in the single-field case - and also that the difference is a direct
consequence of the isocurvature perturbations inherent to multi-field models.
This result leads us to conclude that the notion of adiabaticity is not
invariant under conformal transformations. Using a two-field example we show
that even if in one frame the evolution is adiabatic, meaning that the
curvature perturbation is conserved on super-horizon scales, in general in the
other frame isocurvature perturbations continue to source the curvature
perturbation. We also find that it is possible to realise a particular model in
which curvature perturbations in both frames are conserved but with each being
of different magnitude. These examples highlight that the curvature
perturbation itself, despite being gauge-invariant, does not correspond
directly to an observable. The non-equivalence of the two curvature
perturbations would also be important when considering the addition of Standard
Model matter into the system.Comment: 21 pages, 2 figures, references added, typos corrected, version to
appear in JCA
Social Studies Preservice Teachers’ Citizenship Knowledge and Perceptions of the U.S. Naturalization Test
Teacher educators from six states invited their social studies methodology students to complete an abbreviated version of the U.S. Citizenship and Immigration Services (USCIS) Naturalization Test. The preservice teachers were also asked to share their conceptions of citizenship and evaluate the naturalization test. The findings from this study indicated that although this sample of preservice teachers had limited conceptions of citizenship, most were able to get a satisfactory score on the test. The authors discuss the implications of these results and suggest ways to broaden citizenship education in teacher preparation programs
Anti-prion activity of an RNA aptamer and its structural basis.
Prion proteins (PrPs) cause prion diseases, such as bovine spongiform encephalopathy. The conversion of a normal cellular form (PrP(C)) of PrP into an abnormal form (PrP(Sc)) is thought to be associated with the pathogenesis. An RNA aptamer that tightly binds to and stabilizes PrP(C) is expected to block this conversion and to thereby prevent prion diseases. Here, we show that an RNA aptamer comprising only 12 residues, r(GGAGGAGGAGGA) (R12), reduces the PrP(Sc) level in mouse neuronal cells persistently infected with the transmissible spongiform encephalopathy agent. Nuclear magnetic resonance analysis revealed that R12, folded into a unique quadruplex structure, forms a dimer and that each monomer simultaneously binds to two portions of the N-terminal half of PrP(C), resulting in tight binding. Electrostatic and stacking interactions contribute to the affinity of each portion. Our results demonstrate the therapeutic potential of an RNA aptamer as to prion diseases
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