1,719 research outputs found
Chiral Primordial Gravitational Waves from a Lifshitz Point
We study primordial gravitational waves produced during inflation in quantum
gravity at a Lifshitz point proposed by Hoava. Assuming
power-counting renormalizability, foliation preserving diffeomorphism
invariance, and the condition of detailed balance, we show that primordial
gravitational waves are circularly polarized due to parity violation. The
chirality of primordial gravitational waves is a quite robust prediction of
quantum gravity at a Lifshitz point which can be tested through observations of
cosmic microwave background radiation and stochastic gravitational waves.Comment: 4 pages,2 figures;v2:reference added; v3:reference adde
Quasi Non-linear Evolution of Stochastic Bias
It is generally believed that the spatial distribution of galaxies does not
trace that of the total mass. The understanding of the bias effect is therefore
necessary to determine the cosmological parameters and the primordial density
fluctuation spectrum from the galaxy survey. The deterministic description of
bias may not be appropriate because of the various stochasticity of galaxy
formation process. In nature, the biasing is epoch dependent and recent deep
survey of the galaxy shows the large biasing at high redshift. Hence, we
investigate quasi non-linear evolution of the stochastic bias by using the tree
level perturbation method. Especially, the influence of the initial cross
correlation on the evolution of the skewness and the bi-spectrum is examined in
detail. We find that the non-linear bias can be generated dynamically. The
small value of the initial cross correlation can bend the \dg-\dm relation
effectively and easily lead to the negative curvature (). We also
propose a method to predict the bias, cross correlation and skewness at high
redshift. As an illustration, the possibility of the large biasing at high
redshift is discussed. Provided the present bias parameter as and
, we predict the large scale bias as at by fitting
the bi-spectrum to the Lick catalog data. Our results will be important for the
future deep sky survey.Comment: 20 pages, 5 Encapsulated Postscript figures, aastex, final version to
appear in Ap
Flexible substrate for printed wiring
A very flexible substrate for printed wiring is disclosed which is composed of a blend of phenoxy resin-polyisocyanate-brominated epoxy resin in which the equivalent ration of the functional groups is hydroxyl grouped: isocyanate group: epoxy group = 1:0.2 to 2:0.5 to 3. The product has outstanding solder resistance and is applied to metal without using adhesives
Flexible composite film for printed circuit board
A flexible printed circuit for a printed circuit board in which layers of reaction product composed of a combination of phenoxy resin - polyisocyanate - brominated epoxy resin, and in which the equivalent ratio of those functional groups is hydroxyl group: isocyanate group: epoxy group - 1 : 0.2 to 2 : 0.5 to 3 are laminated on at least one side of saturated polyester film is discussed
Braneworld Flux Inflation
We propose a geometrical model of brane inflation where inflation is driven
by the flux generated by opposing brane charges and terminated by the collision
of the branes, with charge annihilation. We assume the collision process is
completely inelastic and the kinetic energy is transformed into the thermal
energy after collision. Thereafter the two branes coalesce together and behave
as a single brane universe with zero effective cosmological constant. In the
Einstein frame, the 4-dimensional effective theory changes abruptly at the
collision point. Therefore, our inflationary model is necessarily 5-dimensional
in nature. As the collision process has no singularity in 5-dimensional
gravity, we can follow the evolution of fluctuations during the whole history
of the universe. It turns out that the radion field fluctuations have a steeply
tilted, red spectrum, while the primordial gravitational waves have a flat
spectrum. Instead, primordial density perturbations could be generated by a
curvaton mechanism.Comment: 11 pages, 6 figures, references adde
Enumeration and identification of lactic microflora in Algerian goats’ milk
A total of 153 strains of lactic acid bacteria were isolated from Algerian goats’ milk. The strains were identified according to morphological, biochemical and physiological criteria, as well as the use of theAPI system and SDS-PAGE technique. Identification of the isolates revealed the presence of six genera: Enterococcus (41.82%), Lactobacillus (29.40), Lactococcus (19.60%), Leuconostoc (4.57%),Streptococcus thermophilus (3.26%) and Pediococcus (1.30%). The predominant strains belong to Enterococcus faecium (24 isolates), Enterococcus durans (22 isolates), Lactococcus lactis subsp. lactis(25 isolates), Lactobacillus rhamnosus (9 isolates) and Lactobacillus delbrueckii subsp. bulgaricus (7 isolates)
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