1,544 research outputs found
Redshift drift exploration for interacting dark energy
By detecting redshift drift in the spectra of Lyman- forest of
distant quasars, Sandage-Loeb (SL) test directly measures the expansion of the
universe, covering the "redshift desert" of . Thus this
method is definitely an important supplement to the other geometric
measurements and will play a crucial role in cosmological constraints. In this
paper, we quantify the ability of SL test signal by a CODEX-like spectrograph
for constraining interacting dark energy. Four typical interacting dark energy
models are considered: (i) , (ii) ,
(iii) , and (iv) . The results show
that for all the considered interacting dark energy models, relative to the
current joint SN+BAO+CMB+ observations, the constraints on and
would be improved by about 60\% and 30--40\%, while the constraints on
and would be slightly improved, with a 30-yr observation of SL
test. We also explore the impact of SL test on future joint geometric
observations. In this analysis, we take the model with as an
example, and simulate future SN and BAO data based on the space-based project
WFIRST. We find that in the future geometric constraints, the redshift drift
observations would help break the geometric degeneracies in a meaningful way,
thus the measurement precisions of , , , and could
be substantially improved using future probes.Comment: 6 pages, 5 figures; accepted for publication in EPJC. arXiv admin
note: text overlap with arXiv:1407.712
catena-Poly[[(4-aminobenzoato)aquasilver(I)]-μ-hexamethylenetetramine]
In the title coordination polymer, [Ag(C7H6NO2)(C6H12N4)(H2O)]n, the AgI ion is five-coordinated by two carboxylate O atoms from one 4-aminobenzoate anion (L), two N atoms from two different hexamethylenetetramine (hmt) ligands, and one water O atom in a distorted square-pyramidal geometry. The metal atom lies on a mirror plane and the L anion, hmt ligand and water molecule all lie across crystallographic mirror planes. Each hmt ligand bridges two neighboring AgI ions, resulting in the formation of a chain structure along the b axis. The chains are linked into a three-dimensional framework by N—H⋯O and O—H⋯O hydrogen bonds
Wavelength-swept Tm-doped fiber laser operating in the two-micron wavelength band
A wavelength-swept thulium-doped silica fiber laser using an intracavity rotating slotted-disk wavelength scanning filter in combination with an intracavity solid etalon for passive control of temporal and spectral profiles is reported. The laser yielded a wavelength swept output in a step-wise fashion with each laser pulse separated from the previous pulse by a frequency interval equal to the free-spectral-range of the etalon and with an instantaneous linewidth of <0.05 nm. Scanning ranges from 1905 nm to 2049 nm for a cladding-pumping laser configuration, and from 1768 nm to 1956 nm for a core-pumping laser configuration were achieved at average output powers up to ~1 W
3-Hydroxyadamantane-1-acetic acid
The crystal structure of the title adamantane derivative, C12H18O3, has been determined by X-ray diffraction. The structure is stabilized by intermolecular O—H⋯O hydrogen bonds, forming a chain
High-Throughput Computational Screening of Two-Dimensional Semiconductors
By performing high-throughput calculations using density functional theory
combined with a semiempirical van der Waals dispersion correction, we screen 97
direct- and 253 indirect-gap two dimensional nonmagnetic semiconductors from
near 1000 monolayers according to the energetic, thermodynamic, mechanical and
dynamic stability criterions. We present the calculated results including
lattice constants, formation energy, Young's modulus, Poisson's ratio, shear
modulus, band gap, band structure, ionization energy and electron affinity for
all the candidates satisfying our criteria.Comment: 12 pages, 11 figure
Enhanced Neuroprotective Effects by Inter-Ischemia Hypothermia in Cerebral Stroke
Background and Purpose. Studies have shown that inter-ischemia hypothermia is able to reduce the size of myocardial infarctions and improve their clinical outcomes. The present study determined whether inter-ischemia hypothermia induced by pharmacological approach induced stronger neuroprotection in ischemic brains.
Methods. Adult male Sprague-Dawley rats were studied in 4 groups: (1) sham; (2) stroke; (3) stroke treated with pharmacological hypothermia before reperfusion (inter-ischemia hypothermia); and (4) stroke treated with pharmacological hypothermia after reperfusion is initiated (inter-reperfusion hypothermia). The combination of chlorpromazine and promethazine with dihydrocapsaicin was used to induce hypothermia. To compare the neuroprotective effects of drug-induced hypothermia between the groups, brain damage was evaluated using infarct volume and neurological deficits. In addition, mRNA expressions of NADPH oxidase subunits and glucose transporter subtypes were determined by real-time PCR. ROS production was measured by Flow cytometry assay at the same time points.
Results: In both hypothermia groups, cerebral infarct volumes and neurological deficits were reduced. ROS production and the expressions of NOX subunits and glucose transporter subtypes were also significantly reduced in both hypothermia groups as compared to the ischemic group. While there were no statistically significant differences between the two hypothermia groups at 6 h reperfusion, brain damage was significantly further decreased by inter-ischemia hypothermia at 24 h.
Conclusion: Inter-ischemia hypothermia and inter-reperfusion hypothermia after stroke induced neuroprotection by reducing oxidative injury, while neuroprotion was more effective with inter-ischemia hypothermia. This study provides a new avenue and reference for a stronger neuroprotective hypothermia before vascular recanalization in stroke patients
- …