378 research outputs found
Cultural evolution: the case of babiesâ first names
In social sciences, there is currently rare consensus on the underlying mechanism for cultural evolution, partially due to lack of suitable data. The evolution of first names of newborn babies offers a remarkable example for such researches. In this paper, we employ the historical data on baby names from the United States to investigate the evolutionary process of culture, in particular focusing on how inequality among baby names changes over time. Then we propose a stochastic model where individual choice is determined by both individual preference and social influence, and show that the decrease in the strength of social influence can account for all the observed empirical features. Therefore, we claim that the weakening of social influence drives cultural evolution
Klein-Nishina effects on the high-energy afterglow emission of gamma-ray bursts
Extended high-energy(>100MeV) gamma-ray emission that lasts much longer than
the prompt sub-MeV emission has been detected from quite a few gamma-ray bursts
(GRBs) by Fermi Large Area Telescope (LAT) recently. A plausible scenario is
that this emission is the afterglow synchrotron emission produced by electrons
accelerated in the forward shocks. In this scenario, the electrons that produce
synchrotron high-energy emission also undergo inverse-Compton (IC) loss and the
IC scattering with the synchrotron photons should be in the Klein-Nishina
regime. Here we study effects of the Klein-Nishina scattering on the
high-energy synchrotron afterglow emission. We find that, at early times the
Klein-Nishina suppression effect on those electrons that produce the
high-energy emission is usually strong and therefore their inverse-Compton loss
is small with a Compton parameter Y < a few for a wide range of parameter
space. This leads to a relatively bright synchrotron afterglow at high energies
that can be detected by Fermi LAT. As the Klein-Nishina suppression effect
weakens with time, the inverse-Compton loss increases and could dominate over
the synchrotron loss in some parameter space. This will lead to a faster
temporal decay of the high-energy synchrotron emission than what is predicted
by the standard synchrotron model, which may explain the observed rapid decay
of the early high-energy gamma-ray emission in GRB090510 and GRB090902B.Comment: 8 page (emulateapj style), 8 figures, submitted to Ap
Determination of geopotential difference by hydrogen masers based on precise point positioning time-frequency transfer
According to the general relativity theory, the geopotential difference can
be determined by gravity frequency shift between two clocks. Here we report on
the experiments to determine the geopotential difference between two remote
sites by hydrogen masers based on precise point positioning time-frequency
transfer technique. The experiments include the remote clock comparison and the
local clock comparison using two CH1-95 active hydrogen masers linked with
global navigation satellite system time-frequency receivers. The frequency
difference between two hydrogen masers at two sites is derived from the time
difference series resolved by the above-mentioned technique. Considering the
local clock comparison as calibration, the determined geopotential difference
by our experiments is 12,142.3 (112.4) m^2/s^2, quite close to the value
12,153.3 (2.3) m^2/s^2 computed by the EIGEN-6C4 model. Results show that the
proposed approach here for determining geopotential difference is feasible,
operable, and promising for applications in various fields.Comment: 12 pages, 4 figure
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Molecular identification of Trichinella spiralis nudix hydrolase and its induced protective immunity against trichinellosis in BALB/c mice
Background: Nudix hydrolases (Nd) is a widespread superfamily, which is found in all classes of organism, hydrolyse a wide range of organic pyrophosphates and has a âhousecleaningâ function. The previous study showed that Trichinella spiralis Nd (TsNd) bound to intestinal epithelial cells (IECs), and the vaccination of mice with T7 phage-displayed TsNd polypeptides produced protective immunity. The aim of this study was to clone, express and identify the full-length TsNd and to investigate its immune protection against T. spiralis infection. Methods: The full-length cDNA sequence of TsNd gene encoding a 46 kDa protein from T. spiralis intestinal infective larvae (IIL) was cloned and identified. The antigenicity of rTsNd was analyzed by Western blot. Transcription and expression of TsNd at T. spiralis different stages were observed by RT-PCR and IFT. The levels of the specific total IgG, IgG1 and IgG2a antibodies to rTsNd were determined by ELISA. The immune protection of rTsNd against T. spiralis infection was investigated. Results: Sequence and phylogenetic analysis revealed that TsNd had a nudix motif located at 226-244aa, which had high homology and the closest evolutionary status with T. pseudospiralis. The rTsNd was obtained after expression and purification. Western blot analysis showed that anti-rTsNd serum recognized the native TsNd protein in crude antigens of muscle larvae (ML), IIL, adult worms (AW) and newborn larvae (NBL), and ES antigens of ML. Transcription and expression of TsNd gene was observed in all developmental stages of T. spiralis (ML, IIL, AW and NBL), with high level expression in IIL. An immunolocalization analysis identified TsNd in the cuticle, stichocytes and reproductive organs of the parasite. Following immunization, anti-rTsNd IgG levels were increased, and the levels of IgG1 were more significantly higher than that of IgG2a. After a challenge infection with T. spiralis, mice immunized with the rTsNd displayed a 57.7% reduction in adult worms and a 56.9% reduction in muscle larval burden. Conclusions: TsNd induced a partial protective immunity in mice and could be considered as a novel candidate vaccine antigen against trichinellosis
Effect of Xinyue capsules on patients with coronary heart disease after percutaneous coronary intervention: study protocol for a randomized controlled trial
Case report form 2014.3.4R2. (PDF 1119 kb
Population phylogenomic analysis of mitochondrial DNA in wild boars and domestic pigs revealed multiple domestication events in East Asia
A fine-grained mitochondrial DNA phylogenomic analysis was conducted in domestic pigs and wild boars, revealing that pig domestication in East Asia occurred in the Mekong and the middle and downstream regions of the Yangtze river
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