520 research outputs found
On the Detectability of CMB Anisotropies Induced by de Sitter-G\"odel-de Sitter Phase Transition
A geometrical phase transition in the very early Universe, from de Sitter to
G\"odel and back to de Sitter (dGd) spacetimes, can explain the universal
phenomenon of rotation of many large scale structures. This phase transition is
shown to induce fluctuations on the matter and radiation fields with possibly
observable traces. In this work we simulate the dGd-induced inhomogeneities and
use their power spectrum, parametrized by the parameter pair (), as
possible seeds of CMB anisotropies along with the standard inflationary
perturbations. With the Planck 2018 observations, we find
and consistent
with pure inflationary power spectrum and no hint for the dGd transition.
Future large scale surveys can further tighten the constraints and probe the
physics of the early Universe
Massive Spinors and dS/CFT Correspondence
Using the map between free massless spinors on d+1 dimensional Minkowski
spacetime and free massive spinors on , we obtain the boundary term
that should be added to the standard Dirac action for spinors in the dS/CFT
correspondence. It is shown that this map can be extended only to theories with
vertex ({\bar\p}\p)^2 but arbitrary . In the case of scalar field
theories such an extension can be made only for with vertices
, and respectively
The Protective Rolls of Taraxacum officinale against Carbone Tetrachloride Infarction in the Liver
Carbon tetrachloride (CCl4) is a liquid that is colorless, transparent, inflammable, and volatile. Its central carbon atom is surrounded by four Cl- atoms. As a result, the objective of this effort was to estimate the anti-oxidant properties of silver nanoparticles (AgNPs) made utilizing aqueous plant extracts from Taraxacum officinale leaves. A green synthesis of AgNPs using a synergistic aqueous extract from T. officinale leaves was tested against liver damage in rats caused by CCl4. The rats were randomly distributed into seven groups: Group 1: Control group, Group 2: Olive oil group, Group 3: AgNPs-treated group (100 mg/kg BW.), Group 4: AgNPs-treated group (200 mg/kg BW.), Group 5: CCl4 + Olive oil group, Group 6: (CCl4 + Olive Oil) + 100 mg/kg of AgNPs-treated group, and Group 7: (CCl4 + Olive oil) + 200 mg/kg of AgNPs-treated group one a week for 6 weeks. This study demonstrated a sustainable method for synthesizing AgNPs utilizing T. officinale leaf (TOL) extract. To characterize the synthesized T. officinale leaf-silver nanoparticles (TOL-AgNPs), various microscopic and spectroscopic methods were used. The effectiveness of the biosynthesized TOL-AgNPs against CCl4 was tested to assess their antioxidant potential. The antioxidant properties of synthetic TOL-AgNPs were also evaluated. Histopathological research showed that all groups treated with nano-extract had less severe inflammatory responses. Our findings demonstrated that AgNPs synthesized using the leaves of T. officinale possess a potential anti-oxidant activity against CCl4-induced liver injury in rats
Coexistence of OFDM and FBMC for Underlay D2D Communication in 5G Networks
Device-to-device (D2D) communication is being heralded as an important part
of the solution to the capacity problem in future networks, and is expected to
be natively supported in 5G. Given the high network complexity and required
signalling overhead associated with achieving synchronization in D2D networks,
it is necessary to study asynchronous D2D communications. In this paper, we
consider a scenario whereby asynchronous D2D communication underlays an OFDMA
macro-cell in the uplink. Motivated by the superior performance of new
waveforms with increased spectral localization in the presence of frequency and
time misalignments, we compare the system-level performance of a set-up for
when D2D pairs use either OFDM or FBMC/OQAM. We first demonstrate that
inter-D2D interference, resulting from misaligned communications, plays a
significant role in clustered D2D topologies. We then demonstrate that the
resource allocation procedure can be simplified when D2D pairs use FBMC/OQAM,
since the high spectral localization of FBMC/OQAM results in negligible
inter-D2D interference. Specifically, we identify that FBMC/OQAM is best suited
to scenarios consisting of small, densely populated D2D clusters located near
the encompassing cell's edge.Comment: 7 pages, 9 figures, Accepted at IEEE Globecom 2016 Workshop
Turbulent-like fluctuations in quasistatic flow of granular media
We analyze particle velocity fluctuations in a simulated granular system
subjected to homogeneous quasistatic shearing. We show that these fluctuations
share the following scaling characteristics of fluid turbulence in spite of
their different physical origins: 1) Scale-dependent probability distribution
with non-Guassian broadening at small time scales; 2) Power-law spectrum,
reflecting long-range correlations and the self-affine nature of the
fluctuations; 3) Superdiffusion with respect to the mean background flow
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