1,154 research outputs found
A measurement of the Hubble constant using galaxy redshift surveys
We perform a measurement of the Hubble constant, , using the latest
baryonic acoustic oscillations (BAO) measurements from galaxy surveys of 6dFGS,
SDSS DR7 Main Galaxy Sample, BOSS DR12 sample, and eBOSS DR14 quasar sample, in
the framework of a flat CDM model. Based on the Kullback-Leibler (KL)
divergence, we examine the consistency of values derived from various
data sets. We find that our measurement is consistent with that derived from
Planck and with the local measurement of using the Cepheids and type Ia
supernovae. We perform forecasts on from future BAO measurements, and
find that the uncertainty of determined by future BAO data alone,
including complete eBOSS, DESI and Euclid-like, is comparable with that from
local measurements.Comment: 5 pages, 2 figures, 2 tables; accepted for publication in Ap
Tourists' Attitudes Towards Tea Tourism: A Case Study in Xinyang, China
Tea tourism as a new niche market has become more and more popular. Through a case study in Xinyang, China, this research explores tourists' attitudes and perceptions toward tea and tea tourism, identifies who the potential tea tourists are, and compares their attitudes with others. One hundred seventy-nine questionnaires were administered; one-way ANOVA and chi-square test were used based on their willingness of tea tourism. The results suggest that tea tourists and non-tea tourists have significant differences in terms of their attitudes toward tea drinking and their willingness of buying tea as souvenir. Tea tourists are mainly tea lovers driven by their high interest in tea and tea culture; they tend to be both males and females (yet females show a significant higher percentage than males), between ages 31-40, who have a positive attitude toward tea drinking, and who often drink tea. This research also provides some marketing suggestions for this niche market
Performance of commercial MIMO access point in distributed antenna system with different fiber lengths
Post- constraints on interacting vacuum energy
We present improved constraints on an interacting vacuum model using updated
astronomical observations including the first data release from Planck. We
consider a model with one dimensionless parameter, , describing the
interaction between dark matter and vacuum energy (with fixed equation of state
). The background dynamics correspond to a generalised Chaplygin gas
cosmology, but the perturbations have a zero sound speed. The tension between
the value of the Hubble constant, , determined by Planck data plus WMAP
polarisation (Planck+WP) and that determined by the Hubble Space Telescope
(HST) can be alleviated by energy transfer from dark matter to vacuum
(). A positive increases the allowed values of due to
parameter degeneracy within the model using only CMB data. Combining with
additional datasets of including supernova type Ia (SN Ia) and baryon acoustic
oscillation (BAO), we can significantly tighten the bounds on .
Redshift-space distortions (RSD), which constrain the linear growth of
structure, provide the tightest constraints on vacuum interaction when combined
with Planck+WP, and prefer energy transfer from vacuum to dark matter
() which suppresses the growth of structure. Using the combined
datasets of Planck+WP+Union2.1+BAO+RSD, we obtain the constraint on to
be (95% C.L.), allowing low consistent with the
measurement from 6dF Galaxy survey. This interacting vacuum model can alleviate
the tension between RSD and Planck+WP in the CDM model for ,
or between HST measurements of and Planck+WP for , but not both
at the same time.Comment: 15 pages, 12 figures, 3 tables; accepted for publication in Phys.
Rev.
- ā¦