Diurnal tidal oscillations in the coupled atmosphere–ocean system generate important contributions to the Earth’s free core nutation (FCN) and annual and sub-annual components of forced nutation in ...the celestial pole offsets. The determination of FCN parameters cannot avoid the influence of geophysical fluid excitation neither with the direct analysis of FCN signal (direct approaches) nor with the resonance analysis of forced nutation (resonance approaches). There is a significant difference in the FCN parameters obtained with resonance and direct approaches from celestial pole offsets observed through very long baseline interferometry (VLBI). The source of the difference between the two lacks quantitative analysis, which causes difficulties in interpreting the validity of the derived FCN parameters. Using both approaches, we conducted a simulation of celestial pole offsets to quantitatively demonstrate how geophysical fluid excitation affects the determination of FCN parameters from VLBI observations. Using the same excitation source, the FCN period obtained by the direct approach deviated from the set value (430.21 d) by more than 10 d, while the FCN period obtained by the resonance approach showed no deviation from the set value by more than 1 d. The results indicate that the resonance approach more accurately reflects the intrinsic period of the FCN. The impact of atmospheric and oceanic contributions on the determination of the FCN period with the resonance approach was within 2 d. Numerical simulation shows that discrepancies in FCN parameters caused by geophysical excitation were nonnegligible in constructing accurate FCN models.
Recent studies have indicated a correlation between Earth’s free core nutation (FCN) and geomagnetic jerks (GMJs). However, some uncertainties still need to be resolved before their relationship can ...be confirmed. The variations in the amplitude and phase of the FCN result from the comprehensive influence of the surface fluid layer and core–mantle couplings, which makes its correlation with GMJs difficult to verify. The FCN period mainly depends on the inertia coupling and the dissipative couplings (such as viscous, electromagnetic and topographic couplings) at the core–mantle boundary according to the theory of Earth rotation. Whatever the GMJ mechanism, it is most likely to affect the FCN by changing the core–mantle couplings. This study was conducted to effectively determine variations in the FCN period by considering atmospheric and oceanic effects, investigate any correlation between the two phenomena, and analyze how the FCN relates to GMJs. Using the normal time–frequency transform, we extracted signals in the nutation band from the atmospheric and oceanic angular momentum functions. We used the broadband Liouville equations to estimate the atmospheric and oceanic effects on nutation terms. Using a sliding window of 2 years, we fitted five nutation terms most affected by FCN resonance from the celestial pole offsets with FCN model removed. The FCN period variation was estimated by using weighted least square method. The results indicated a correlation between the FCN and GMJ. Further, we analyzed the relationship between the geomagnetic fluctuations and FCN based on both the core–mantle couplings and the possible GMJ mechanism.
The synthesis, preclinical profile, and in vivo efficacy in rat xenograft models of the novel and selective anaplastic lymphoma kinase inhibitor 15b (LDK378) are described. In this initial report, ...preliminary structure-activity relationships (SARs) are described as well as the rational design strategy employed to overcome the development deficiencies of the first generation ALK inhibitor 4 (TAE684). Compound 15b is currently in phase 1 and phase 2 clinical trials with substantial antitumor activity being observed in ALK-positive cancer patients.
High-precision gravity measurements provide an invaluable approach for exploring the interior of the Earth by detecting geodynamic phenomena generated by different physical processes. China has ...established a very extensive and diverse gravity observation network, including high-precision superconducting gravimeters, gPhones, and other kinds of gravity instruments. The observational data accumulated from these instruments over a long period has facilitated important achievements in a variety of geodynamic applications. This paper briefly introduces some recently important research progress in background noise analysis, gravity tides, liquid core dynamics, hum signal, and normal mode detection based on China’s gravity network and its cooperation with the international gravity network.
Dental caries is the most frequent biofilm-related human infectious disease in the oral cavity.
Streptococcus mutans
is one of the primary etiological agents of dental caries. The aim of our study ...was to investigate the effects of rhein-8-O-β-D-glucopyranoside (Rg) on the development of
S. mutans
biofilms. Growth curves were generated, and biofilm oxygen sensitivity was detected after Rg treatment. The expression levels of
luxS
,
brpA
,
ffh
,
recA
,
nth,
and
smx
were analyzed by real-time PCR. The trypan blue exclusion assay was used to measure the effect of Rg on monocyte viability. The results showed that Rg could significantly inhibit the growth of
S. mutans
and suppress the biofilm formation of
S. mutans
in a concentration-dependent manner. In Rg-treated biofilms, the expression levels of
luxS
,
brpA
,
ffh
,
recA
,
nth,
and
smx
were all decreased. Our results further showed that Rg was nontoxic, as Rg did not affect monocyte viability or lactate dehydrogenase activity in the exposed cells. These results suggested that Rg inhibited the biofilm formation of
S. mutans
, and the decrease in
luxS
,
brpA
,
ffh
,
recA
,
nth,
and
smx
expression might contribute to the antibacterial effects of Rg.
In order to verify the time variability of free core nutation (FCN) period, global superconducting gravimeter (SG) observations were analyzed based on synthetic test data. The gravity data series ...were synthesized to check the detectability of resonance variation caused by FCN period change. The tests indicate that the discrepancy between the FCN periods determined by SG and VLBI observations is caused by the high correlation between the FCN parameter and the amplitude factor of the ψ1 wave. The K1 wave is more sensitive to the FCN period change than other diurnal waves. The limit of the standard deviation of the K1 wave is found for more precisely observing the FCN period change. Tidal parameters of diurnal waves estimated from long series of 20 global SG stations were analyzed. A common variation trend is found in the amplitude factor of both K1 and ψ1 waves in all 8 stations above the limit, which indicates the FCN period may be not so stable in time. Furthermore, the variation in the K1 and ψ1 waves constrains the FCN period change to between 2.5 and 4 sidereal days, which also agrees with the possible variation from the current VLBI and SG observations.
The effects of microstructure morphology on corresponding tensile mechanical properties of Ti–5Al–5Mo–5V–1Cr–1Fe alloy controlling by three different heat treatment conditions (solution, single-step ...and two-step aging) were investigated in the present paper. The results show that the solution temperature exhibited an important impact on the precipitation behavior of secondary-α phase (αs) during aging, in which the content of αs gradually increased with the increase of solution temperature. When the alloy was single-step aged at 500–600 °C, the needle-like αs precipitated from matrix, as well as the content of αs decreased and coarsened corresponding to the increase of aging temperature. Compared with single-step aging, the αs slightly increased when the alloy was subjected to two-step aging heat treatment. The tensile results show that the αs is the main strengthening phase in the alloy. Moreover, its content as well as the intensity of the precipitation mode directly affects the strength, whereas inevitably with an accompanying penalty on ductility. In general, the higher solution temperature and the lower first-step aging temperature result in a more intensive αs and then lead to the higher strength. Meanwhile, {101¯2} and {101¯1} twins were found in two-step aged tensile samples, which may impart twinning-induced plasticity (TWIP). Overall, this study demonstrates that the alloy can be heat treated to achieve an excellent match between strength and ductility and to provide sufficient stress and optional ductility (ultimate strength of 978–1439 MPa and elongation of 8.25–18.9%).
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•Three different heat treatment conditions (solution, single-step and two-step aging) were investigated in this paper.•An excellent combination of strength and ductility can be obtained via two-step aging treatment.•Both tensile and compression twins were found near the tensile fracture of the two-step aged alloy.
Haemaphysalis longicornis, a vector of various pathogens with medical and veterinary importance, is native to eastern Asia, and recently reached the USA as an emerging disease threat. In this study, ...we aimed to identify the geographical distribution, hosts, and associated pathogens of H longicornis.
Data were collected from multiple sources, including a field survey, reference book, literature review, and related websites. The thematic maps showing geographical distribution of H longicornis and associated pathogens were produced by ArcGIS. Hosts of H longicornis and positive rates for H longicornis-associated pathogens were estimated by meta-analysis. Ecological niche modelling was used to predict potential global distribution of H longicornis.
H longicornis was found to be present in ten countries, predominantly in eastern Asia, the USA, Australia, and New Zealand. The tick was known to feed on a variety of domestic and wild animals, and humans. At least 30 human pathogens were associated with H longicornis, including seven species of spotted fever group rickettsiae, seven species in the family of Anaplasmataceae, four genospecies in the complex Borrelia burgdorferi sensu lato, two Babesia species, six species of virus, and Francisella, Bartonella, Coxiella, and Toxoplasma, which were mainly reported in eastern Asia. The predictive modelling revealed that H longicornis might affect more extensive regions, including Europe, South America, and Africa, where the tick has never been recorded before.
H longicornis is relatively common in the world, and is associated with various human and animal pathogens. Authorities and health-care workers should be aware of the threat of the tick species to public health and veterinary medicine. Surveillance and further investigations should be enhanced globally.
National Natural Science Foundation of China and National Key Research and Development Program of China.
Modern geodetic technologies such as high-precision ground gravity measurements, satellite gravity measurements, the global navigation satellite system, remote sensing methods, etc. provide rich ...observation data for monitoring various geodynamic processes of the global Earth and its surface. The 19th International Symposium on Geodynamics and Earth Tides brought together scientific researchers from 26 countries around the world, shared the application of various measurements in different geoscience issues, covering Earth tidal deformation, oceanic and atmospheric loading effects, earthquake cycle, hydrology, Earth rotation changes, etc., and provided a precious exchange platform for global peers.
The Earth's Free Core Nutation (FCN) causes Earth tides and forced nutation with frequencies close to the FCN that exhibit resonance effects. High-precision superconducting gravimeter (SG) and very ...long baseline interferometry (VLBI) provide good observation techniques for detecting the FCN parameters. However, some choices in data processing and solution procedures increase the uncertainty of the FCN parameters. In this study, we analyzed the differences and the effectiveness of weight function and ocean tide corrections in the FCN parameter detection using synthetic data, SG data from thirty-one stations, and the 10 celestial pole offset (CPO) series. The results show that significant discrepancies are caused by different computing options for a single SG station. The stacking method, which results in a variation of 0.24–5 sidereal days (SDs) in the FCN period (T) and 103-104 in the quality factor (Q) due to the selection of the weighting function and the ocean tide model (OTM), can effectively suppress this influence. The statistical analysis results of synthetic data shows that although different weight choices, while adjusting the proportion of diurnal tidal waves involved, do not significantly improve the accuracy of fitted FCN parameters from gravity observations. The study evaluated a series of OTMs using the loading correction efficiency. The fitting of FCN parameters can be improved by selecting the mean of appropriate OTMs based on the evaluation results. Through the estimation of the FCN parameters based on the forced nutation, it was found that the weight function P1 is more suitable than others, and different CPO series (after 2009) resulted in a difference of 0.4 SDs in the T and of 103 in the Q. We estimated the FCN parameters for SG (T = 430.4 ± 1.5 SDs and Q = 1.52 × 104 ± 2.5 × 103) and for VLBI (T = 429.8 ± 0.7 SDs, Q = 1.88 × 104 ± 2.1 × 103).
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