280 research outputs found
Testing the Distance-Duality Relation with a Combination of Cosmological Distance Observations
In this paper, we propose an accurate test of the distance-duality (DD)
relation, (where and are
the luminosity distances and angular diameter distances, respectively), with a
combination of cosmological observational data of Type Ia Supernave (SNe Ia)
from Union2 set and the galaxy cluster sample under an assumption of spherical
model. In order to avoid bias brought by redshift incoincidence between
observational data and to consider redshift error bars of both clusters and SNe
Ia in analysis, we carefully choose the SNe Ia points which have the minimum
acceptable redshift difference of the galaxy cluster sample (). By assuming a
constant and functions of the redshift parameterized by six different
expressions, we find that there exists no conceivable evidence for variations
in the DD relation concerning with observational data, since it is well
satisfied within confidence level for most cases. Further considering
different values of in constraining, we also find that the choosing
of may play an important role in this model-independent test of the
distance-duality relation for the spherical sample of galaxy clusters.Comment: 9 pages, 4 figures, 1 table. accepted for publication in Res. Astron.
Astrophy
Testing the phenomenological interacting dark energy with observational data
In order to test the possible interaction between dark energy and dark
matter, we investigate observational constraints on a phenomenological
scenario, in which the ratio between the dark energy and matter densities is
proportional to the power law case of the scale factor, . By using the Markov chain Monte Carlo method,
we constrain the phenomenological interacting dark energy model with the newly
revised data, as well as the cosmic microwave background (CMB)
observation from the 7-year Wilkinson Microwave Anisotropy Probe (WMAP7)
results, the baryonic acoustic oscillation (BAO) observation from the
spectroscopic Sloan Digital Sky Survey (SDSS) data release 7 (DR7) galaxy
sample and the type Ia supernovae (SNe Ia) from Union2 set. The best-fit values
of the model parameters are
,
, and
, which are more
stringent than previous results. These results show that the standard
CDM model without any interaction remains a good fit to the recent
observational data; however, the interaction that the energy transferring from
dark matter to dark energy is slightly favored over the interaction from dark
energy to dark matter. It is also shown that the data can give more
stringent constraints on the phenomenological interacting scenario when
combined to CMB and BAO observations, and the confidence regions of
+BAO+CMB, SNe+BAO+CMB, and +SNe+BAO+CMB combinations are consistent
with each other.Comment: 6 pages, 4 figures, 1 table. MNRAS in pres
Neural Basis and Motor Imagery Intervention Methodology Based on Neuroimaging Studies in Children With Developmental Coordination Disorders: A Review.
Although the neural bases of the brain associated with movement disorders in children with developmental coordination disorder (DCD) are becoming clearer, the information is not sufficient because of the lack of extensive brain function research. Therefore, it is controversial about effective intervention methods focusing on brain function. One of the rehabilitation techniques for movement disorders involves intervention using motor imagery (MI). MI is often used for movement disorders, but most studies involve adults and healthy children, and the MI method for children with DCD has not been studied in detail. Therefore, a review was conducted to clarify the neuroscientific basis of the methodology of intervention using MI for children with DCD. The neuroimaging review included 20 magnetic resonance imaging studies, and the neurorehabilitation review included four MI intervention studies. In addition to previously reported neural bases, our results indicate decreased activity of the bilateral thalamus, decreased connectivity of the sensory-motor cortex and the left posterior middle temporal gyrus, bilateral posterior cingulate cortex, precuneus, cerebellum, and basal ganglia, loss of connectivity superiority in the abovementioned areas. Furthermore, reduction of gray matter volume in the right superior frontal gyrus and middle frontal gyrus, lower fractional anisotropy, and axial diffusivity in regions of white matter pathways were found in DCD. As a result of the review, children with DCD had less activation of the left brain, especially those with mirror neurons system (MNS) and sensory integration functions. On the contrary, the area important for the visual space processing of the right brain was activated. Regarding of characteristic of the MI methods was that children observed a video related to motor skills before the intervention. Also, they performed visual-motor tasks before MI training sessions. Adding action observation during MI activates the MNS, and performing visual-motor tasks activates the basal ganglia. These methods may improve the deactivated brain regions of children with DCD and may be useful as conditioning before starting training. Furthermore, we propose a process for sharing the contents of MI with the therapist in language and determining exercise strategies
High‐Entropy Lithium Argyrodite Solid Electrolytes Enabling Stable All‐Solid‐State Batteries
Superionic solid electrolytes (SEs) are essential for bulk-type solid-state battery (SSB) applications. Multicomponent SEs are recently attracting attention for their favorable charge-transport properties, however a thorough understanding of how configurational entropy (ΔSconf) affects ionic conductivity is lacking. Here, we successfully synthesized a series of halogen-rich lithium argyrodites with the general formula Li5.5PS4.5ClxBr1.5-x (0≤x≤1.5). Using neutron powder diffraction and 31P magic-angle spinning nuclear magnetic resonance spectroscopy, the S2−/Cl−/Br− occupancy on the anion sublattice was quantitatively analyzed. We show that disorder positively affects Li-ion dynamics, leading to a room-temperature ionic conductivity of 22.7 mS cm−1 (9.6 mS cm−1 in cold-pressed state) for Li5.5PS4.5Cl0.8Br0.7 (ΔSconf=1.98R). To the best of our knowledge, this is the first experimental evidence that configurational entropy of the anion sublattice correlates with ion mobility. Our results indicate the possibility of improving ionic conductivity in ceramic ion conductors by tailoring the degree of compositional complexity. Moreover, the Li5.5PS4.5Cl0.8Br0.7 SE allowed for stable cycling of single-crystal LiNi0.9Co0.06Mn0.04O2 (s-NCM90) composite cathodes in SSB cells, emphasizing that dual-substituted lithium argyrodites hold great promise in enabling high-performance electrochemical energy storage
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