25,740 research outputs found
The Gauge Dual of Gauged N=8 Supergravity Theory
The most general SU(3)-singlet space of gauged N=8 supergravity in
four-dimensions is studied recently. The SU(3)-invariant six scalar fields are
realized by six real four-forms. A family of holographic N=1 supersymmetric RG
flows on M2-branes in three-dimensions is described. This family of flows is
driven by three independent mass parameters from the N=8 SO(8) theory and is
controlled by two IR fixed points, N=1 G_2-invariant one and N=2 SU(3) x
U(1)-invariant one. The generic flow with arbitrary mass parameters is N=1
supersymmetric and reaches to the N=2 SU(3) x U(1) fixed point where the three
masses become identical. A particular N=1 supersymmetric SU(3)-preserving RG
flow from the N=1 G_2-invariant fixed point to the N=2 SU(3) x U(1)-invariant
fixed point is also discussed.Comment: 19pp; added the footnote 1, improved the conclusion and to appear in
IJMP
Maximum Matching in Turnstile Streams
We consider the unweighted bipartite maximum matching problem in the one-pass
turnstile streaming model where the input stream consists of edge insertions
and deletions. In the insertion-only model, a one-pass -approximation
streaming algorithm can be easily obtained with space , where
denotes the number of vertices of the input graph. We show that no such result
is possible if edge deletions are allowed, even if space is
granted, for every . Specifically, for every , we show that in the one-pass turnstile streaming model, in order to compute
a -approximation, space is
required for constant error randomized algorithms, and, up to logarithmic
factors, space is sufficient. Our lower bound result is
proved in the simultaneous message model of communication and may be of
independent interest
Perturbing Around A Warped Product Of AdS_4 and Seven-Ellipsoid
We compute the spin-2 Kaluza-Klein modes around a warped product of AdS_4 and
a seven-ellipsoid. This background with global G_2 symmetry is related to a
U(N) x U(N) N=1 superconformal Chern-Simons matter theory with sixth order
superpotential. The mass-squared in AdS_4 is quadratic in G_2 quantum number
and KK excitation number. We determine the dimensions of spin-2 operators using
the AdS/CFT correspondence. The connection to N=2 theory preserving SU(3) x
U(1)_R is also discussed.Comment: 21pp; The second and last paragraphs of section 2, the footnotes 1
and 2 added and to appear in JHE
Meta-Stable Brane Configurations by Adding an Orientifold-Plane to Giveon-Kutasov
In hep-th/0703135, they have found the type IIA intersecting brane
configuration where there exist three NS5-branes, D4-branes and anti-D4-branes.
By analyzing the gravitational interaction for the D4-branes in the background
of the NS5-branes, the phase structures in different regions of the parameter
space were studied in the context of classical string theory. In this paper, by
adding the orientifold 4-plane and 6-plane to the above brane configuration, we
describe the intersecting brane configurations of type IIA string theory
corresponding to the meta-stable nonsupersymmetric vacua of these gauge
theories.Comment: 21 pp, 6 figures; reduced bytes of figures, DBI action analysis added
and to appear in JHE
Titania/alumina bilayer gate insulators for InGaAs metal-oxide-semiconductor devices
We describe the electrical properties of atomic layer deposited TiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> bilayer gate oxides which simultaneously achieve high gate capacitance density and low gate leakage current density. Crystallization of the initially amorphous TiO<sub>2</sub> film contributes to a significant accumulation capacitance increase (∼33%) observed after a forming gas anneal at 400 °C. The bilayer dielectrics reduce gate leakage current density by approximately one order of magnitude at flatband compared to Al<sub>2</sub>O<sub>3</sub> single layer of comparable capacitance equivalent thickness. The conduction band offset of TiO<sub>2</sub> relative to InGaAs is 0.6 eV, contributing to the ability of the stacked dielectric to suppress gate leakage conduction
Supersymmetry Breaking Vacua from M Theory Fivebranes
We consider intersecting brane configurations realizing N=2 supersymmetric
gauge theories broken to N=1 by multitrace superpotentials, and softly to N=0.
We analyze, in the framework of M5-brane wrapping a curve, the supersymmetric
vacua and the analogs of spontaneous supersymmetry breaking and soft
supersymmetry breaking in gauge theories. We show that the M5-brane does not
exhibit the analog of metastable spontaneous supersymmetry breaking, and does
not have non-holomorphic minimal volume curves with holomorphic boundary
conditions. However, we find that any point in the N=2 moduli space can be
rotated to a non-holomorphic minimal volume curve, whose boundary conditions
break supersymmetry. We interpret these as the analogs of soft supersymmetry
breaking vacua in the gauge theory.Comment: 32 pages, 8 figures, harvmac; v2: corrections in eq. 3.6 and in
section 6, reference adde
Strain Gradients in Epitaxial Ferroelectrics
X-ray analysis of ferroelectric thin layers of Ba1/2Sr1/2TiO3 with different
thickness reveals the presence of internal strain gradients across the film
thickness and allows us to propose a functional form for the internal strain
profile. We use this to calculate the direct influence of strain gradient,
through flexoelectric coupling, on the degradation of the ferroelectric
properties of thin films with decreasing thickness, in excellent agreement with
the observed behaviour. This work highlights the link between strain relaxation
and strain gradients in epitaxial films, and shows the pressing need to avoid
strain gradients in order to obtain thin ferroelectrics with bulk-like
properties.Comment: 4 pages, 3 embedded figures (1 color), revTex
Ribosome Biogenesis Modulates Ty1 Copy Number Control in Saccharomyces cerevisiae.
Transposons can impact the host genome by altering gene expression and participating in chromosome rearrangements. Therefore, organisms evolved different ways to minimize the level of transposition. In Saccharomyces cerevisiae and its close relative S. paradoxus, Ty1 copy number control (CNC) is mediated by the self-encoded restriction factor p22, which is derived from the GAG capsid gene and inhibits virus-like particle (VLP) assembly and function. Based on secondary screens of Ty1 cofactors, we identified LOC1, a RNA localization/ribosome biogenesis gene that affects Ty1 mobility predominantly in strains harboring Ty1 elements. Ribosomal protein mutants rps0bΔ and rpl7aΔ displayed similar CNC-specific phenotypes as loc1Δ, suggesting that ribosome biogenesis is critical for CNC. The level of Ty1 mRNA and Ty1 internal (Ty1i) transcripts encoding p22 was altered in these mutants, and displayed a trend where the level of Ty1i RNA increased relative to full-length Ty1 mRNA. The level of p22 increased in these mutants, and the half-life of p22 also increased in a loc1Δ mutant. Transcriptomic analyses revealed small changes in the level of Ty1 transcripts or efficiency of translation initiation in a loc1Δ mutant. Importantly, a loc1Δ mutant had defects in assembly of Gag complexes and packaging Ty1 RNA. Our results indicate that defective ribosome biogenesis enhances CNC by increasing the level of p22, and raise the possibility for versatile links between VLP assembly, its cytoplasmic environment, and a novel stress response
Temperature Abuse Affects the Quality of Irradiated Pork Loins
Temperature abuse had no significant effect on color, oxidation, and volatiles of irradiated pork loins. However, temperature abuse improved water holding capacity of meat, which could be caused by the accelerated hydrolysis of muscle proteins at higher temperature. Irradiation increased redness, sulfur contents in volatiles and off-odor of pork loin. Off-odor and redness induced by irradiation sustained during storage. Among sulfur compounds, the content of dimethyl disulfide decreased gradually while the level of thiourea remained relatively constant. Irradiation also increased water loss, which might be related to the structural damage in membrane during irradiation. This study shows that temperature abuse has little effect on the quality of irradiated por
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