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

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

ANALYSIS OF THE TRANSFORMATION OF THE VELOCITY OF THE CENTER OF GRAVITY IN RUNNING SINGLE LEG HORIZONTAL JUMP

The purpose of this study was to analyze the transformation of the center of gravity (CG) in the running single leg horizontal jump and to investigate the influence of the forward rotation of the takeoff leg in achieving vertical CG velocity. The subjects were 98 male long jumpers, whose mean best official jump among their recorded trials was 7.16 ± 0.66 m. Their takeoff motion was videotaped with two high-speed cameras. Horizontal CG velocity at touchdown and vertical CG velocity at toe-off had significantly positive correlations with jumping distance; the decrease in horizontal CG velocity during the takeoff phase was significantly and negatively correlated with jumping distance. Forward rotation of the spring-mass model did not contribute to an increase in vertical CG velocity, although it did contribute to an increase in horizontal CG velocity just before toe-off

STUDIES ON THE DISTRIBUTION OF THE EPILACHNID BEETLES IN GUMMA PREFECTURE, JAPAN

The authors have studied the distribution of the Epilachnid beetles in Gumma-pref. since 1956, and the following results are obtained as summary. 1. Epilachna sparsa is recognized to be distributed to some extent at the southern plain places of Gumma-pref. such as Tomioka, Takasaki, Maebashi, Ogomachi, Isezaki, Ota, Tatebayashi, Kasakakemura and their neighbors, where the altitude is less than 150m (Fig. 1). At these places sparsa lives intermingled with 28-maculata. 2. At the higher places with 150～300m altitude such as Shibukawa, Onogami, Yoshioka, Misato, Akagimura, Hokkitsumura, Komochimura and their neighbors (Fig. 1), sparsa tends to live being segregated from 28-maculata in the same farm. 3. The species feeds usually on the Solanaceous plants, among which ground cherry is the best host plant. The number of the generation is generally two but rarely three. 4. E. 28-maculata is the species having the widest distribution in Gumma-pref. (Fig. 1) and we can see it everywhere, potatoes, egg-plants and tomatoes are planted, with exception of one place near Ozegahara. The highest limit of the distribution may be 1300m. 5. The host plant of 28-maculata is the Solanaceous plants with the exception of ground cherry and redpepper, on which the larvae cannot grow. The number of the generation is one but very rarely may be two. 6. Ea pustulosa inhabits mainly at the northern places of Gumma-pref. such as Anabara, Hikagenango, Neri, Akagizawabashi, Tokusa, Kashozan, Akakura, Doai, Fujiwara, Uenohara, Sugenuma, H6shi and Omineyama. All these places are located along the Tone River system with more than 600m altitude and have heavy snowfall (Fig. 1). However, pustulosa is also found at Sebayashi of Tano-gun in the southwest Gumma. 7. The true host plant of pustulosa is the thistle (Cirsium nipponicum (MAXIM.) MAKINO var. incomptum (FR. et SAV.) KITAM. belonging to Compositae in Gumma-pref., but the beetle eats sometimes the Solanaceous plants espe-cially potato-plant. With an exceptional case the authors observed that the adults were attacking burdock leaves. 8. The distribution of sparsa is expanding northwardly year after year in Kanto District and the northern limit of the distribution runs along the line denoted in Fig. 3 and 4 at present. 9. This phenomenon is not only noticeable for ecological problem, but also very important for agriculture because the beetle probably gives a fear of attacking the Solanaceous vegetables as a new pest in the new habitats.ArticleJournal of the Faculty of Textile Science and Technology, Shinshu University. Ser. A, Biology 13: 1-23(1964)departmental bulletin pape

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 $f(R)$ 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 $f(R)$ 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

Kinematic characteristics of barefoot sprinting in habitually shod children

Background. Anecdotally, a wide variety of benefits of barefoot running have been advocated by numerous individuals. The influence of the alterations in the properties of the shoe on the running movement has been demonstrated in adults at submaximal jogging speeds. However, the biomechanical differences between shod and barefoot running in children at sprinting speeds and the potential developmental implications of these differences are still less examined. The purpose was to determine the potential differences in habitually shod children's sprint kinematics between shod and barefoot conditions. Methods. Ninety-four children (51 boys and 43 girls; 6-12 years-old; height, 135.0 ± 0.12 m; body mass, 29.0 ± 6.9 kg) performed 30 m maximal sprints from standing position for each of two conditions (shod and barefoot). To analyze sprint kinematics within sagittal plane sprint kinematics, a high-speed camera (300 fps) was set perpendicular to the runway. In addition, sagittal foot landing and take-offimages were recorded for multiple angles by using five high-speed cameras (300 fps). Spatiotemporal variables, the kinematics of the right leg (support leg) and the left leg (recovery leg), and foot strike patterns: rear-foot strike (RFS), mid-foot strike (MFS), and forefoot strike (FFS) were investigated. The paired t -test was used to test difference between shod and barefoot condition. Results. Barefoot sprinting in habitually shod children was mainly characterized by significantly lower sprint speed, higher step frequency, shorter step length and stance time. In shod running, 82% of children showed RFS, whereas it decreased to 29% in barefoot condition. The touch down state and the subsequent joint movements of both support and recovery legs during stance phase were significantly altered when running in condition with barefoot. Discussion. The acute effects of barefoot sprinting was demonstrated by significantly slower sprinting speeds that appear to reflect changes in a variety of spatiotemporal parameters as well as lower limb kinematics. It is currently unknown whether such differences would be observed in children who typically run in bare feet and what developmental benefits and risks may emerge from increasing the proportion of barefoot running and sprinting in children. Future research should therefore investigate potential benefits that barefoot sprinting may have on the development of key physical fitness such as nerve conduction velocity, muscular speed, power, and sprinting technique and on ways to minimize the risk of any acute or chronic injuries associated with this activity. © 2018 Mizushima et al

X-Ray Reflection Nebulae with Large Equivalent Widths of Neutral Iron Ka Line in the Sgr C Region

This paper reports on the first results of the Suzaku observation in the Sgr C region. We detected four diffuse clumps with strong line emission at 6.4keV, Ka from neutral or low-ionized Fe. One of them, M359.38-0.00, is newly discovered with Suzaku. The X-ray spectra of the two bright clumps, M359.43-0.07 and M359.47-0.15, after subtracting the Galactic center diffuse X-ray emission (GCDX), exhibit strong Ka line from FeI with large equivalent widths (EWs) of 2.0-2.2keV and clear Kb of FeI. The GCDX in the Sgr C region is composed of the 6.4keV- and 6.7keV-associated components. These are phenomenologically decomposed by taking relations between EWs of the 6.4keV and 6.7keV lines. Then the former EWs against the associated continuum in the bright clump regions are estimated to be 2.4(+2.3_-0.7)keV. Since the two different approaches give similar large EWs of 2keV, we strongly suggest that the 6.4keV clumps in the Sgr C region are due to X-ray reflection/fluorescence (the X-ray reflection nebulae).Comment: Accepted for publication in PAS

Unusual diffuse X-ray source in the Galactic center region

We report the ASCA and Chandra discovery of a diffuse X-ray source in the Galactic center region. The X-ray spectrum is fitted with a non-equilibrium ionization (NEI) plasma model of about 6-keV temperature. The model requires higher than solar metal abundances, a young plasma age of $\simeq$ 100 years and a large N_H value of about 10^{23} cm^{-2}. The N_H value constrains the source position to be in the Galactic center region at about 8.5 kpc distance. The high resolution X-ray image with the Chandra ACIS shows a ring of 10'' radius which corresponds to 0.4 pc at the Galactic center, and a tail-like structure. Although the morphology is peculiar, the other X-ray features are likely to be a very young supernova remnant, possibly in a free expansion phase.Comment: 11 pages, 4 figures, to be published in Ap