367 research outputs found
Properties of Sand Cement Brick Containing Quarry Dust (SCBQD) and Bacteria Strain
Sand cement brick among favorable building material for low cost house construction due to its low price. Technology development in building material already explored varies waste to be added in improving properties of building materials. Beside that addition of bacteria in building material also proven in literature to improve its properties. In this research addition of bacteria in the cement sand block containing quarry dust (SCBQD) was studied. Several properties namely, compressive strength, depth of carbonation, initial rate of suction (IRS) and water absorption were studied. SCBQD is made from sand, cement, quarry dust and chipping using industrial mix design. In this study, 3% of Enterococcus faecalis (EF) and 5% of Bacillus sp (BSP) bacteria was added in the SCBQD mixes. Three SCBQD mixes were prepared including the control mix without bacteria, SCBQD with 3% EF and SCBQD with 5% BSP. Natural fine aggregate was replaced partially with the quarry dust. 100 mm SCBQD cubes were used to conduct compressive strength, depth of carbonation, initial rate of suction and water absorption test at 7, 14 and 28 days. The experimental results showed that the compressive strength value of SCBQD with addition of bacteria was increased for all curing ages. At 28 days of curing, the compressive strength value for control SCBQD containing quarry without any addition of bacteria is 3.30 MPa, while SCBQD containing quarry dust with addition of 3% of EF bacteria is 3.57 MPa and for SCBQD with 5% of BSP bacteria the value is 4.90 MPa. On the other hand, SCBQD containing 3% EF and 5% BSP gained lower IRS and carbonation depth. Depth of carbonation at 28 days was decreased 9.3% and 20% for SCBQD containing 3% EF and 5% BSP, respectively. Meanwhile, 28-day IRS was reduced 12.9% and 22.6% for SCBQD containing 3% EF and 5% BSP, respectively. In overall, the result shows that, SCBQD with 5% BSP as proven positive and better results when compared to control SCBQD and SCBQD with 3% EF bacteria which is absorb of 12.02% in water absorption. The findings showed that bio-SCBQD containing industrial waste and bacteria has good potential to be used as building material
Effects of Nonlinear Dispersion Relations on Non-Gaussianities
We investigate the effect of non-linear dispersion relations on the
bispectrum. In particular, we study the case were the modified relations do not
violate the WKB condition at early times, focusing on a particular example
which is exactly solvable: the Jacobson-Corley dispersion relation with quartic
correction with positive coefficient to the squared linear relation. We find
that the corrections to the standard result for the bispectrum are suppressed
by a factor where is the scale where the modification
to the dispersion relation becomes relevant. The modification is {\it mildly}
configuration-dependent and equilateral configurations are more suppressed with
respect to the local ones, by a factor of one percent. There is no
configuration leading to enhancements. We then analyze the results in the
framework of particle creation using the approximate gluing method of
Brandenberger and Martin, which relates more directly to the modeling of the
trans-Planckian physics via modifications of the vacuum at a certain cutoff
scale. We show that the gluing method overestimates the leading order
correction to the spectrum and bispectrum by one and two orders, respectively,
in . We discuss the various approximation and conclude that for
dispersion relations not violating WKB at early times the particle creation is
small and does not lead to enhanced contributions to the bispectrum. We also
show that in many cases enhancements do not occur when modeling the
trans-Planckian physics via modifications of the vacuum at a certain cutoff
scale. Most notably they are only of order O(1) when the Bogolyubov
coefficients accounting for particle creation are determined by the Wronskian
condition and the minimization of the uncertainty between the field and its
conjugate momentum.Comment: v1: 11 pages, 2 figures; v2: references update
Janus and Multifaced Supersymmetric Theories
We investigate the various properties Janus supersymmetric Yang-Mills
theories. A novel vacuum structure is found and BPS monopoles and dyons are
studied. Less supersymmetric Janus theories found before are derived by a
simpler method. In addition, we find the supersymmetric theories when the
coupling constant depends on two and three spatial coordinates.Comment: 20 pages, no figures, typos, equations corrected. Additional comment
Uniqueness of the gauge invariant action for cosmological perturbations
In second order perturbation theory different definitions are known of gauge
invariant perturbations in single field inflationary models. Consequently the
corresponding gauge invariant cubic actions do not have the same form. Here we
show that the cubic action for one choice of gauge invariant variables is
unique in the following sense: the action for any other, non-linearly related
variable can be brought to the same bulk action, plus additional boundary
terms. These boundary terms correspond to the choice of hypersurface and
generate extra, disconnected contributions to the bispectrum. We also discuss
uniqueness of the action with respect to conformal frames. When expressed in
terms of the gauge invariant curvature perturbation on uniform field
hypersurfaces the action for cosmological perturbations has a unique form,
independent of the original Einstein or Jordan frame. Crucial is that the gauge
invariant comoving curvature perturbation is frame independent, which makes it
extremely helpful in showing the quantum equivalence of the two frames, and
therefore in calculating quantum effects in nonminimally coupled theories such
as Higss inflation.Comment: 27 page
Gravitational Wave Spectrum in Inflation with Nonclassical States
The initial quantum state during inflation may evolve to a highly squeezed
quantum state due to the amplification of the time-dependent parameter,
, which may be the modified dispersion relation in
trans-Planckian physics. This squeezed quantum state is a nonclassical state
that has no counterpart in the classical theory. We have considered the
nonclassical states such as squeezed, squeezed coherent, and squeezed thermal
states, and calculated the power spectrum of the gravitational wave
perturbation when the mode leaves the horizon.Comment: 21 page
Possible role of bonding angle and orbital mixing in iron pnictide superconductivity: Comparative electronic structure studies of LiFeAs and Sr2VO3FeAs
1
On the dissipative non-minimal braneworld inflation
We study the effects of the non-minimal coupling on the dissipative dynamics
of the warm inflation in a braneworld setup, where the inflaton field is
non-minimally coupled to induced gravity on the warped DGP brane. We study with
details the effects of the non-minimal coupling and dissipation on the
inflationary dynamics on the normal DGP branch of this scenario in the
high-dissipation and high-energy regime. We show that incorporation of the
non-minimal coupling in this setup decreases the number of e-folds relative to
the minimal case. We also compare our model parameters with recent
observational data.Comment: 32 pages, 6 figures. arXiv admin note: substantial text overlap with
arXiv:1001.044
Ab initio atomistic thermodynamics and statistical mechanics of surface properties and functions
Previous and present "academic" research aiming at atomic scale understanding
is mainly concerned with the study of individual molecular processes possibly
underlying materials science applications. Appealing properties of an
individual process are then frequently discussed in terms of their direct
importance for the envisioned material function, or reciprocally, the function
of materials is somehow believed to be understandable by essentially one
prominent elementary process only. What is often overlooked in this approach is
that in macroscopic systems of technological relevance typically a large number
of distinct atomic scale processes take place. Which of them are decisive for
observable system properties and functions is then not only determined by the
detailed individual properties of each process alone, but in many, if not most
cases also the interplay of all processes, i.e. how they act together, plays a
crucial role. For a "predictive materials science modeling with microscopic
understanding", a description that treats the statistical interplay of a large
number of microscopically well-described elementary processes must therefore be
applied. Modern electronic structure theory methods such as DFT have become a
standard tool for the accurate description of individual molecular processes.
Here, we discuss the present status of emerging methodologies which attempt to
achieve a (hopefully seamless) match of DFT with concepts from statistical
mechanics or thermodynamics, in order to also address the interplay of the
various molecular processes. The new quality of, and the novel insights that
can be gained by, such techniques is illustrated by how they allow the
description of crystal surfaces in contact with realistic gas-phase
environments.Comment: 24 pages including 17 figures, related publications can be found at
http://www.fhi-berlin.mpg.de/th/paper.htm
Observational constraints on Horava-Lifshitz cosmology
We use observational data from Type Ia Supernovae (SNIa), Baryon Acoustic
Oscillations (BAO), and Cosmic Microwave Background (CMB), along with
requirements of Big Bang Nucleosynthesis (BBN), to constrain the cosmological
scenarios governed by Horava-Lifshitz gravity. We consider both the detailed
and non-detailed balance versions of the gravitational sector, and we include
the matter and radiation sectors. We conclude that the detailed-balance
scenario cannot be ruled out from the observational point of view, however the
corresponding likelihood contours impose tight constraints on the involved
parameters. The scenario beyond detailed balance is compatible with
observational data, and we present the corresponding stringent constraints and
contour-plots of the parameters. Although this analysis indicates that
Horava-Lifshitz cosmology can be compatible with observations, it does not
enlighten the discussion about its possible conceptual and theoretical
problems.Comment: 11 pages, 6 figures, version published in JCA
The Conformal Transformation in General Single Field Inflation with Non-Minimal Coupling
The method of a conformal transformation is applied to a general class of
single field inflation models with non-minimal coupling to gravity and
non-standard kinetic terms, in order to reduce the cosmological perturbative
calculation to the conventional minimal coupling case to all orders in
perturbation theory. Our analysis is made simple by the fact that all
perturbation variables in the comoving gauge are conformally invariant to all
orders. The structure of the vacuum, on which cosmological correlation
functions are evaluated, is also discussed. We show how quantization in the
Jordan frame for non-minimally coupled inflation models can be equivalently
implemented in the Einstein frame. It is thereafter argued that the general
N-point cosmological correlation functions (of the curvature perturbation) are
independent of the conformal frame.Comment: 15 pages, no figure, references adde
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