230 research outputs found
Eddington-inspired Born-Infeld gravity: nuclear physics constraints and the validity of the continuous fluid approximation
In this paper we investigate the classical non-relativistic limit of the
Eddington-inspired Born-Infeld theory of gravity. We show that strong bounds on
the value of the only additional parameter of the theory \kappa, with respect
to general relativity, may be obtained by requiring that gravity plays a
subdominant role compared to electromagnetic interactions inside atomic nuclei.
We also discuss the validity of the continuous fluid approximation used in this
and other astrophysical and cosmological studies. We argue that although the
continuous fluid approximation is expected to be valid in the case of
sufficiently smooth density distributions, its use should eventually be
validated at a quantum level.Comment: 3 page
Value of supplier's capacity information in a two-echelon supply chain
Cataloged from PDF version of article.In traditional supply chain models it is generally assumed that full information is
available to all parties involved. Although this seems reasonable, there are cases where chain
members are independent agents and possess different levels of information. In this study,
we analyze a two-echelon, single supplier-multiple retailers supply chain in a single-period
setting where the capacity of the supplier is limited. Embedding the lack of information
about the capacity of the supplier in the model, we aim to analyze the reaction of the retailers,
compare it with the full-information case, and assess the value of information and the
effects of information asymmetry using game theoretic analysis. In our numerical studies,
we conclude that the value of information is highly dependent on the capacity conditions
and estimates of the retailers, and having information is not necessarily beneficial to the
retailers
The effect of feed made from fish processing waste silage on the growth of rainbow trout (Oncorhynchus mykiss)
This study researched the degree to which the growth of rainbow trout (Oncorhynchus mykiss) was influenced by pellet feed made from silage produced from waste generated by the fish food processing industry. During the 90 day trial, a completely random parcel method was used with three repetitions. The average weight of the rainbow trout was 54.05±235 g, while their average length was 17.46±0.11 cm. One hundred (100) trout were stocked (25 kg/m3) in each fiberglass fish feeding tank. Four different experimental groups were formed; feed without silage (control) and pellets with 25, 50 and 100% silage. Fish were fed twice per a day until they were satisfied (ad libitum). At the end of the study, the group that was fed with feed made from 50% silage increased the most in weight, followed by the control group and the groups fed with 25 and 100% silage, respectively. The average weight differences between the groups were found to be significant (P<0.05). In conclusion, it can be said that replacing the fish meal in food used to feed trout with 50% fish silage has a positive effect on growth, and that silage can be used in trout food at the aforementioned ratio.Key words: Fish meal, fish silage, growth, feed efficiency, rainbow trout
All unitary cubic curvature gravities in D dimensions
We construct all the unitary cubic curvature gravity theories built on the
contractions of the Riemann tensor in D -dimensional (anti)-de Sitter
spacetimes. Our construction is based on finding the equivalent quadratic
action for the general cubic curvature theory and imposing ghost and tachyon
freedom, which greatly simplifies the highly complicated problem of finding the
propagator of cubic curvature theories in constant curvature backgrounds. To
carry out the procedure we have also classified all the unitary quadratic
models. We use our general results to study the recently found cubic curvature
theories using different techniques and the string generated cubic curvature
gravity model. We also study the scattering in critical gravity and give its
cubic curvature extensions.Comment: 24 pages, 1 figure, v2: A subsection on cubic curvature extensions of
critical gravity is added, v3: The part regarding critical gravity is
revised. Version to appear in Class. Quant. Gra
Electrical Properties of Al/p-Si Structures with Colchicine Organic Thin Film
In this study, we have fabricated an Al/Colchicine/p-Si structure and have investigated its current–
voltage (I–V) and capacitance–voltage (C–V) characteristics at room temperature. The barrier height and
ideality factor values of 0.68 eV and 3.22, respectively, have been obtained from the I-V plot. The value of
the barrier height was compared with the barrier height value of 0.50 eV of a conventional Al/p-Si diode.
This was attributed to the Colchicine organic film modifying the effective barrier height by affecting the
space charge region of the inorganic Si semiconductor substrate. By using C – 2-V characteristics the diffusion
potential value has been extracted as 1.32 V.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3514
Massive Gravity Theories and limits of Ghost-free Bigravity models
We construct a class of theories which extend New Massive Gravity to higher
orders in curvature in any dimension. The lagrangians arise as limits of a new
class of bimetric theories of Lovelock gravity, which are unitary theories free
from the Boulware-Deser ghost. These Lovelock bigravity models represent the
most general non-chiral ghost-free theories of an interacting massless and
massive spin-two field in any dimension. The scaling limit is taken in such a
way that unitarity is explicitly broken, but the Boulware-Deser ghost remains
absent. This automatically implies the existence of a holographic -theorem
for these theories. We also show that the Born-Infeld extension of New Massive
Gravity falls into our class of models demonstrating that this theory is also
free of the Boulware-Deser ghost. These results extend existing connections
between New Massive Gravity, bigravity theories, Galileon theories and
holographic -theorems.Comment: 11+5 page
Generalised massive gravity one-loop partition function and AdS/(L)CFT
The graviton 1-loop partition function is calculated for Euclidean
generalised massive gravity (GMG) using AdS heat kernel techniques. We find
that the results fit perfectly into the AdS/(L)CFT picture. Conformal
Chern-Simons gravity, a singular limit of GMG, leads to an additional
contribution in the 1-loop determinant from the conformal ghost. We show that
this contribution has a nice interpretation on the conformal field theory side
in terms of a semi-classical null vector at level two descending from a primary
with conformal weights (3/2,-1/2).Comment: 25 p., 2 jpg figs, v2: added 6 lines of clarifying text after Eq.
(2.38
Hamiltonian analysis of BHT massive gravity
We study the Hamiltonian structure of the Bergshoeff-Hohm-Townsend (BHT)
massive gravity with a cosmological constant. In the space of coupling
constants , our canonical analysis reveals the special role of
the condition . In this sector, the dimension of the
physical phase space is found to be , which corresponds to two
Lagrangian degree of freedom. When applied to the AdS asymptotic region, the
canonical approach yields the conserved charges of the BTZ black hole, and
central charges of the asymptotic symmetry algebra.Comment: LATEX, 21 pages; v2: minor correction
Extra gauge symmetries in BHT gravity
We study the canonical structure of the Bergshoeff-Hohm-Townsend massive
gravity, linearized around a maximally symmetric background. At the critical
point in the space of parameters, defined by , we discover an
extra gauge symmetry, which reflects the existence of the partially massless
mode. The number of the Lagrangian degrees of freedom is found to be 1. We show
that the canonical structure of the theory at the critical point is unstable
under linearization.Comment: LATEX, 12 page
- …