1,018 research outputs found
Beyond consistency test of gravity with redshift-space distortions at quasi-linear scales
Redshift-space distortions (RSD) offer an attractive method to measure the
growth of cosmic structure on large scales, and combining with the measurement
of the cosmic expansion history, it can be used as cosmological tests of
gravity. With the advent of future galaxy redshift surveys aiming at precisely
measuring the RSD, an accurate modeling of RSD going beyond linear theory is a
critical issue in order to detect or disprove small deviations from general
relativity (GR). While several improved models of RSD have been recently
proposed based on the perturbation theory (PT), the framework of these models
heavily relies on GR. Here, we put forward a new PT prescription for RSD in
general modified gravity models. As a specific application, we present
theoretical predictions of the redshift-space power spectra in f(R) gravity
model, and compare them with N-body simulations. Using the PT template that
takes into account the effects of both modifications of gravity and RSD
properly, we successfully recover the fiducial model parameter in N-body
simulations in an unbiased way. On the other hand, we found it difficult to
detect the scale dependence of the growth rate in a model-independent way based
on GR templates.Comment: 17 pages, 9 figures, version accepted for publication in PR
STRUCTURE OF THE OCCIPITAL REGION IN PIERIDAE (LEPIDOPTERA) FROM JAPAN
The structure of the occipital region in the Pierid butterflies mainly from Japan was observed. As the result, Leptidea was separable from the other species by the form of occipital prominence. The others were divided into 2 groups and 4 subgroups. Catopsilia resembled very closely Pierinae while Aporia and Anthocharis are very similar to Coliadenae in the occipital structure.ArticleJournal of the Faculty of Textile Science and Technology, Shinshu University. Ser. A, Biology 23: 1-22(1981)departmental bulletin pape
MORPHOLOGICAL STUDIES ON THE OCCIPITAL REGION OF NYMPHALIDAE AND LIBYTHEIDAE (LEPIDOPTERA) FROM JAPAN
The occipital morphology of 54 species belonging to Nymphalidae and Libytheidae was studied with reference to its bearing on phylogenical grouping. 1. The occipital region consists of three main parts, viz. dorsal part of occiput, postocular plate and occipital foramen. Further the dorsal part of occiput is divisible into occipital prominence, intermediate plate and connection part, and postocular plate into marginal furrow, scale region and basal part of occiput. 2. Libytheidae is distinguished from Nymphalidae by main three characters. 3. The occipital morphology in Charaxinae is greatly different from that of the other subfamilies in Nymphalidae. It seems suitable to separate Charaxinae from Nymphalidae. 4. The occipital morphology in Dichorragia nesimachus nesiotes differs from that of Apaturinae markedly. 5. In the genus Limenitis, L. populi is very different from L. glorifica and L. camilla in the occipital morphology, and so it is inacceptable to treat them as one genus. 6. Vanessa indica and Cynthia cardui are so similar to each other in the occipital morphology that it is unable to treat them as the different genus.ArticleJournal of the Faculty of Textile Science and Technology, Shinshu University. Ser. A, Biology 20: 1-47(1978).departmental bulletin pape
Regularized cosmological power spectrum and correlation function in modified gravity models
Based on the multi-point propagator expansion, we present resummed
perturbative calculations for cosmological power spectra and correlation
functions in the context of modified gravity. In a wide class of modified
gravity models that have a screening mechanism to recover general relativity
(GR) on small scales, we apply the eikonal approximation to derive the
governing equation for resummed propagator that partly includes the
non-perturbative effect in the high-k limit. The resultant propagator in the
high-k limit contains the new corrections arising from the screening mechanism
as well as the standard exponential damping. We explicitly derive the
expression for new high-k contributions in specific modified gravity models,
and find that in the case of f(R) gravity for a currently constrained model
parameter, the corrections are basically of the sub-leading order and can be
neglected. Thus, in f(R) gravity, similarly to the GR case, we can analytically
construct the regularized propagator that reproduces both the resummed high-k
behavior and the low-k results computed with standard perturbation theory,
consistently taking account of the nonlinear modification of gravity valid at
large scales. With the regularized multi-point propagators, we give predictions
for power spectrum and correlation function at one-loop order, and compare
those with N-body simulations in f(R) gravity model. As an important
application, we also discuss the redshift-space distortions and compute the
anisotropic power spectra and correlation functions.Comment: 25 pages, 7 figure
Non-linear Evolution of Matter Power Spectrum in Modified Theory of Gravity
We present a formalism to calculate the non-linear matter power spectrum in
modified gravity models that explain the late-time acceleration of the Universe
without dark energy. Any successful modified gravity models should contain a
mechanism to recover General Relativity (GR) on small scales in order to avoid
the stringent constrains on deviations from GR at solar system scales. Based on
our formalism, the quasi non-linear power spectrum in the
Dvali-Gabadadze-Porratti (DGP) braneworld models and gravity models are
derived by taking into account the mechanism to recover GR properly. We also
extrapolate our predictions to fully non-linear scales using the Parametrized
Post Friedmann (PPF) framework. In gravity models, the predicted
non-linear power spectrum is shown to reproduce N-body results. We find that
the mechanism to recover GR suppresses the difference between the modified
gravity models and dark energy models with the same expansion history, but the
difference remains large at weakly non-linear regime in these models. Our
formalism is applicable to a wide variety of modified gravity models and it is
ready to use once consistent models for modified gravity are developed.Comment: 25 pages, 8 figures, comparison to N-body simulations in DGP added,
published in PR
Numerical study of curvature perturbations in a brane-world inflation at high-energies
We study the evolution of scalar curvature perturbations in a brane-world
inflation model in a 5D Anti-de Sitter spacetime. The inflaton perturbations
are confined to a 4D brane but they are coupled to the 5D bulk metric
perturbations. We numerically solve full coupled equations for the inflaton
perturbations and the 5D metric perturbations using Hawkins-Lidsey inflationary
model. At an initial time, we assume that the bulk is unperturbed. We find that
the inflaton perturbations at high energies are strongly coupled to the bulk
metric perturbations even on subhorizon scales, leading to the suppression of
the amplitude of the comoving curvature perturbations at a horizon crossing.
This indicates that the linear perturbations of the inflaton field does not
obey the usual 4D Klein-Gordon equation due to the coupling to 5D gravitational
field on small scales and it is required to quantise the coupled brane-bulk
system in a consistent way in order to calculate the spectrum of the scalar
perturbations in a brane-world inflation.Comment: 16 pages, 5 figure
Mechanisms regulating nutrition-dependent developmental plasticity through organ-specific effects in insects
Nutrition, via the insulin/insulin-like growth factor (IIS)/Target of Rapamycin (TOR) signaling pathway, can provide a strong molding force for determining animal size and shape. For instance, nutrition induces a disproportionate increase in the size of male horns in dung and rhinoceros beetles, or mandibles in staghorn or horned flour beetles, relative to body size. In these species, well-fed male larvae produce adults with greatly enlarged horns or mandibles, whereas males that are starved or poorly fed as larvae bear much more modest appendages. Changes in IIS/TOR signaling plays a key role in appendage development by regulating growth in the horn and mandible primordia. In contrast, changes in the IIS/TOR pathway produce minimal effects on the size of other adult structures, such as the male genitalia in fruit flies and dung beetles. The horn, mandible and genitalia illustrate that although all tissues are exposed to the same hormonal environment within the larval body, the extent to which insulin can induce growth is organ specific. In addition, the IIS/TOR pathway affects body size and shape by controlling production of metamorphic hormones important for regulating developmental timing, like the steroid molting hormone ecdysone and sesquiterpenoid hormone juvenile hormone. In this review, we discuss recent results from Drosophila and other insects that highlight mechanisms allowing tissues to differ in their sensitivity to IIS/TOR and the potential consequences of these differences on body size and shape.FCT fellowships, Fundação Calouste Gulbenkian
Equivalence principle violation in Vainshtein screened two-body systems
In massive gravity, galileon, and braneworld explanations of cosmic acceleration, force modifications are screened by nonlinear derivative self-interactions of the scalar field mediating that force. Interactions between the field of a central body (“A”) and an orbiting body (“B”) imply that body B does not move as a test body in the field of body A if the orbit is smaller than the Vainshtein radius of body B. We find through numerical solutions of the joint field at the position of B that the A-field Laplacian is nearly perfectly screened by the B self-field, whereas first derivative or net forces are reduced in a manner that scales with the mass ratio of the bodies as (M_B/M_A)^(3/5). The latter causes mass-dependent reductions in the universal perihelion precession rate due to the fifth force, with deviations for the Earth-Moon system at the ∼4% level. In spite of universal coupling, which preserves the microscopic equivalence principle, the motion of macroscopic screened bodies depends on their mass providing in principle a means for testing the Vainshtein mechanism
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