1,414 research outputs found
Ultrafast Relaxation Dynamics of Photoexcited Dirac Fermion in The Three Dimensional Dirac Semimetal Cadmium Arsenide
Three dimensional (3D) Dirac semimetals which can be seen as 3D analogues of
graphene have attracted enormous interests in research recently. In order to
apply these ultrahigh-mobility materials in future electronic/optoelectronic
devices, it is crucial to understand the relaxation dynamics of photoexcited
carriers and their coupling with lattice. In this work, we report ultrafast
transient reflection measurements of the photoexcited carrier dynamics in
cadmium arsenide (Cd3As2), which is one of the most stable Dirac semimetals
that have been confirmed experimentally. By using low energy probe photon of
0.3 eV, we probed the dynamics of the photoexcited carriers that are
Dirac-Fermi-like approaching the Dirac point. We systematically studied the
transient reflection on bulk and nanoplate samples that have different doping
intensities by tuning the probe wavelength, pump power and lattice temperature,
and find that the dynamical evolution of carrier distributions can be retrieved
qualitatively by using a two-temperature model. This result is very similar to
that of graphene, but the carrier cooling through the optical phonon couplings
is slower and lasts over larger electron temperature range because the optical
phonon energies in Cd3As2 are much lower than those in graphene
Y Chromosomes of 40% Chinese Are Descendants of Three Neolithic Super-grandfathers
Demographic change of human populations is one of the central questions for
delving into the past of human beings. To identify major population expansions
related to male lineages, we sequenced 78 East Asian Y chromosomes at 3.9 Mbp
of the non-recombining region (NRY), discovered >4,000 new SNPs, and identified
many new clades. The relative divergence dates can be estimated much more
precisely using molecular clock. We found that all the Paleolithic divergences
were binary; however, three strong star-like Neolithic expansions at ~6 kya
(thousand years ago) (assuming a constant substitution rate of 1e-9/bp/year)
indicates that ~40% of modern Chinese are patrilineal descendants of only three
super-grandfathers at that time. This observation suggests that the main
patrilineal expansion in China occurred in the Neolithic Era and might be
related to the development of agriculture.Comment: 29 pages of article text including 1 article figure, 9 pages of SI
text, and 2 SI figures. 5 SI tables are in a separate ancillary fil
1,5-Bis(4-bromophenyl)-3-phenylpentane-1,5-dione
The asymmetric unit of the title compound, C23H18Br2O2, contains two independent molecules with slightly different conformations. In the absence of classical intermolecular interactions, the crystal packing is stabilized by van der Waals forces
Proteome analysis of male accessory gland secretions in oriental fruit flies reveals juvenile hormone-binding protein, suggesting impact on female reproduction
In insects, the accessory gland proteins (Acps) secreted by male accessory glands (MAGs) account for the majority of seminal fluids proteins. Mixed with sperm, they are transferred to the female at mating and so impact reproduction. In this project, we identified 2,927 proteins in the MAG secretions of the oriental fruit fly Bactrocera dorsalis, an important agricultural pest worldwide, using LC-MS analysis, and all sequences containing open reading frames were analyzed using signalP. In total, 90Acps were identified. About one third (26) of these 90 Acps had a specific functional description, while the other two thirds (64) had no functional description including dozens of new classes of proteins. Hence, several of these novel Acps were abundant in the MAG secretions, and we confirmed their MAG-specific expression by qPCR. Finally and interestingly, one of these novel proteins was functionally predicted as juvenile hormone-binding protein, suggesting the impact of Acps with reproductive events in the female. Our results will aid in the development of an experimental method to identify Acps in insects, and in turn this information with new Acps in B. dorsalis will pave the way of further exploration their function in reproduction and potential development as new insecticide targets
The relationship between hepatic resistin overexpression and inflammation in patients with nonalcoholic steatohepatitis
BACKGROUND: The relationship between resistin and non-alcoholic steatohepatitis (NASH) is not clear, some studies claimed that serum resistin levels were associated with neither the presence of NASH nor its severity, others declared that serum resistin was related with inflammation and fibrosis in NASH. Our animal study verified that the distribution of resistin in the liver is correlated with inflammation in NASH. However, there is no pertinent study in humans. METHODS: Thirty patients with NASH, 28 simple steatosis, and 43 controls were recruited. Blood was collected for resistin, liver chemistries, fasting insulin and some metabolic parameters. Liver histology was scored according to NAFLD activity scoring system. Hepatic resistin expression was examined by real-time polymerase chain reaction, immunohistochemistry. Resistin protein expression was confirmed by western blotting in 13 patients with concomitant NAFLD and gallstone. RESULTS: Serum resistin was significantly elevated in both NASH and simple steatotic subjects compared with controls (all P < 0.05). Hepatic resistin was significantly increased in NASH patients in both mRNA and protein levels than those in simple steatosis and control subjects (all P < 0.05). Both serum and hepatic resistin had a correlation with obesity, but not with insulin resistance. The distribution of resistin positive cells was predominantly in perisinusoidal cells (such as Kupffer cells and hepatic stellate cells) in human NASH. Multivariate analysis revealed that waist-hip ratio, higher serum triglyceride, and hyperresistinemia were independent factors related to higher grade of steatosis; whereas hepatic resistin and serum cytokeratin predict NASH and severity of liver fibrosis. CONCLUSIONS: Hepatic resistin overexpression in NASH patients is associated with the severity of liver inflammation and fibrosis. Liver-derived resistin may be involved in the pathogenesis of human NASH
Experimental Trapped-ion Quantum Simulation of the Kibble-Zurek dynamics in momentum space
The Kibble-Zurek mechanism is the paradigm to account for the nonadiabatic
dynamics of a system across a continuous phase transition. Its study in the
quantum regime is hindered by the requisite of ground state cooling. We report
the experimental quantum simulation of critical dynamics in the
transverse-field Ising model by a set of Landau-Zener crossings in
pseudo-momentum space, that can be probed with high accuracy using a single
trapped ion. We test the Kibble-Zurek mechanism in the quantum regime in the
momentum space and find the measured scaling of excitations is in accordance
with the theoretical prediction.Comment: 10 pages, 3 figures Published in Scientific Reports,
http://www.nature.com/articles/srep3338
Observational signature of continuously operating drivers of decayless kink oscillation
Decayless kink oscillations, which are nearly omnipresent in the solar
corona, are believed to be driven by continuously operating energy supply. In
this letter, we investigate an external continuous excitation of an apparent
decayless oscillation during an X1.1 flare on June 20, 2023
(SOL2023-06-20T16:42).The decayless kink oscillation was identified in the
coronal loop at extreme ultraviolet (EUV) wavelengths and the associated flare
quasi-periodic pulsations (QPPs) were simultaneously observed in passbands of
hard X-ray (HXR), microwave, and ultraviolet (UV) emissions. The kink
oscillation is detected as a transverse oscillation of the coronal loop, which
reveals five apparent cycles with an average period of about 130-10 s. The
oscillation amplitude does not show any significantly decay, suggesting a
decayless oscillation. At the same time, the solar flare occurs in the vicinity
of the oscillating loop and exhibits five main pulses in HXR, microwave, and UV
emissions, which could be regarded as flare QPPs. They have similar periods of
about 100-130 s, which may indicate successive and repetitive energy releases
during the flare impulsive phase. The peak of each loop oscillation cycle
appears to follow the pulse of the QPPs, suggesting that the transverse
oscillation is closely associated with flare QPPs. Our observations support the
scenario where the repetitive energy released following flare QPPs could be
invoked as external, continuously operating drivers of the apparent decayless
kink oscillation.Comment: accepted by A&
(Z)-4-[(Ethylamino)(furan-2-yl)methylidene]-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one
In the crystal of the title compound, C17H17N3O2, the molecules exist in the keto–enamine form. The pyrazole ring is oriented at 10.59 (4) and 57.98 (5)° to the phenyl and furyl rings, respectively, and the dihedral angle between phenyl and furyl rings is 73.30 (11)°. An intramolecular N—H⋯O hydrogen bond occurs between imino and carbonyl groups. In the crystal, weak C—H⋯O hydrogen bonds link the molecules into supramolecular chains along the b axis
The unsynchronized changes of CT image and nucleic acid detection in COVID-19: reports the two cases from Gansu, China
The novel coronavirus disease (COVID-19) outbreak started in December 2019 in Wuhan, China, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The CT image is used to assess the disease progress, whereas the continued two times of negative results from SARS-CoV-2 nucleic acid detection had been considered as a criterion for ending antiviral treatment. We compared the two COVID-19 cases with similar backgrounds and CT image repeated intervals under treatment. Our report highlighted the unsynchronized expression in the changes of CT image and nucleic acid detection in COVID-19, and lasting positive nucleic acid test result in patients recovered from pneumonia. It may be contributed to recognize the disease and improve prevention.Peer reviewe
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