Drastic miniaturization of electronics and ingression of next-generation nanomaterials into space technology have provoked a renaissance in interplanetary flights and near-Earth space exploration ...using small unmanned satellites and systems. As the next stage, the NASA's 2015 Nanotechnology Roadmap initiative called for new design paradigms that integrate nanotechnology and conceptually new materials to build advanced, deep-space-capable, adaptive spacecraft. This review examines the cutting edge and discusses the opportunities for integration of nanomaterials into the most advanced types of electric propulsion devices that take advantage of their unique features and boost their efficiency and service life. Finally, we propose a concept of an adaptive thruster.
A symmetry-preserving approach to the two valence-body continuum bound-state problem is used to calculate the elastic electromagnetic form factors of the ρ-meson and subsequently to study the ...evolution of vector-meson form factors with current-quark mass. To facilitate a range of additional comparisons, K* form factors are also computed. The analysis reveals that vector mesons are larger than pseudoscalar mesons; composite vector mesons are nonspherical, with magnetic and quadrupole moments that deviate ∼30% from point-particle values; in many ways, vector-meson properties are as much influenced by emergent mass as those of pseudoscalars; and vector-meson electric form factors possess a zero at spacelike momentum transfer. Qualitative similarities between the electric form factors of the ρ and the proton, GEp, are used to argue that the character of emergent mass in the Standard Model can force a zero in GEp. Moreover, the existence of a zero in vector-meson electric form factors entails that a single-pole vector-meson dominance model can only be of limited use in estimating properties of off-shell vector mesons, providing poor guidance for systems in which the Higgs mechanism of mass generation is dominant.
Summary
Background
Coronavirus disease 2019 (COVID-19) is a global pandemic but the follow-up data of discharged patients was barely described.
Aim
To investigate clinical outcomes, distribution of ...quarantine locations and the infection status of the contacts of COVID-19 patients after discharge.
Design
A prospective cohort study.
Methods
Demographics, baseline characteristics of 131 COVID-19 patients discharged from 3 February 2020 to 21 February 2020 in Wuhan, China were collected and analyzed by reviewing the medical records retrospectively. Post-hospitalization data related to clinical outcomes, quarantine locations and close contact history were obtained by following up the patients every week up to 4 weeks.
Results
Fifty-three (40.05%) patients on discharge had cough (29.01%), fatigue (7.63%), expectoration (6.11%), chest tightness (6.11%), dyspnea (3.82%), chest pain (3.05%) and palpitation (1.53%). These symptoms constantly declined in 4 weeks post-discharge. Transient fever recurred in 11 (8.4%) patients. Among the discharged patients, 78 (59.5%) underwent chest CT and 2 (1.53%) showed deterioration. A total of 94 (71.8%) patients received SARS-CoV-2 retest and 8 (6.10%) reported positive. Seven (2.29%) patients were readmitted because of fever or positive SARS-CoV-2 retest. After discharge, 121 (92.37%) and 4 (3.05%) patients were self-quarantined at home or community spots, respectively, after a close contact with 167 persons in total who were free of COVID-19 at the endpoint of study.
Conclusion
The majority of COVID-19 patients after discharge were in the course of recovery. Readmission was required in rare cases due to suspected recurrence of COVID-19. Although no contacted infection observed, appropriate self-quarantine and regular re-examination are necessary, particularly for those who have recurred symptoms.
Genomic selection holds a great promise to accelerate plant breeding via early selection before phenotypes are measured, and it offers major advantages over marker-assisted selection for highly ...polygenic traits. In addition to genomic data, metabolome and transcriptome are increasingly receiving attention as new data sources for phenotype prediction. We used data available from maize as a model to compare the predictive abilities of three different omic data sources using eight representative methods for six traits. We found that the best linear unbiased prediction overall performs better than other methods across different traits and different omic data, and genomic prediction performs better than transcriptomic and metabolomic predictions. For the same maize data, we also conducted genome-wide association study, transcriptome-wide association studies and metabolome-wide association studies for the six agronomic traits using both the genome-wide efficient mixed model association (GEMMA) method and a modified least absolute shrinkage and selection operator (LASSO) method. The new LASSO method has the ability to perform statistical tests. Simulation studies show that the modified LASSO performs better than GEMMA in terms of high power and low Type 1 error.
The Kondo insulator SmB6 has long been known to exhibit low-temperature transport anomalies whose origin is of great interest. Here we uniquely access the surface electronic structure of the ...anomalous transport regime by combining state-of-the-art laser and synchrotron-based angle-resolved photoemission techniques. We observe clear in-gap states (up to ~4 meV), whose temperature dependence is contingent on the Kondo gap formation. In addition, our observed in-gap Fermi surface oddness tied with the Kramers' point topology, their coexistence with the two-dimensional transport anomaly in the Kondo hybridization regime, as well as their robustness against thermal recycling, taken together, collectively provide strong evidence for protected surface metallicity with a Fermi surface whose topology is consistent with the theoretically predicted topological Fermi surface. Our observations of systematic surface electronic structure provide the fundamental electronic parameters for the anomalous Kondo ground state of correlated electron material SmB6.
Room-temperature phosphorescence materials are manufactured by a facile click reaction between phosphor and polymer.
To achieve efficient polymer-based room-temperature phosphorescence (RTP) ...materials, covalently embedding phosphors into the polymer matrix appeared as the most appealing approach. However, it is still highly challenging to fabricate RTP materials on a large scale because of the inefficient binding engineering and time-consuming covalent reactions. Here, we have proposed a scalable preparation approach for RTP materials by the facile B─O click reaction between boronic acid–modified phosphors and polyhydroxy polymer matrix. The ab initio molecular dynamics simulations demonstrated that the phosphors were effectively immobilized, resulting in the suppressed nonradiative transitions and activated RTP emission. In comparison to the reported covalent binding time of several hours, such a B─O click reaction can be accomplished within 20 s under ambient environment. The developed strategy simplified the construction of polymer-based RTP polymeric materials by the introduction of facile click chemistry. Our success provides inspirations and possibilities for the scale-up production of RTP materials.
To explore the characteristics of Helicobacter pylori resistance in China and the association between antibiotic resistance and several clinical factors.
H. pylori strains were collected from ...patients in 13 provinces or cities in China between 2010 and 2016. Demographic data including type of disease, geographic area, age, gender and isolation year were collected to analyse their association with antibiotic resistance. Antibiotic resistance was detected using the Etest test and the Kirby-Bauer disc diffusion method.
H. pylori were successfully cultured from 1117 patients. The prevalence of metronidazole, clarithromycin (CLA), azithromycin, levofloxacin (LEV), moxifloxacin, amoxicillin (AMO), tetracycline and rifampicin resistance was 78.2, 22.1, 23.3, 19.2, 17.2, 3.4, 1.9 and 1.5%, respectively. No resistance to furazolidone was observed. The resistance rates to LEV and moxifloxacin were higher in strains isolated from patients with gastritis compared to those with duodenal ulcer and among women. Compared to patients ≥40 years old, younger patients exhibited lower resistance rates to CLA, azithromycin, LEV and moxifloxacin. The resistance rates to CLA and AMO were higher in strains isolated more recently, and we also found that the prevalence of resistance to metronidazole, CLA, azithromycin and AMO were significantly different among different regions of China.
The resistance rates to metronidazole, CLA and LEV were high in China. Patient age, gender, disease and location were associated with the resistance of H. pylori to some antibiotics. Furazolidone, AMO and tetracycline are better choices for H. pylori treatment in China.
Using angle-resolved photoemission spectroscopy, we report electronic structure for representative members of ternary topological insulators. We show that several members of this family, such as Bi ...sub(2)Se sub(2)Te, Bi sub(2)Te sub(2)Se, and GeBi sub(2) Te sub(4), exhibit a singly degenerate Dirac-like surface state, while Bi sub(2)Se sub(2)S is a fully gapped insulator with no measurable surface state. One of these compounds, Bi sub(2)Se sub(2) Te, shows tunable surface state dispersion upon its electronic alloying with Sb (Sb sub(x)Bi sub(2-x)Se sub(2) Te series). Other members of the ternary family such as GeBi sub(2)Te sub(4) and BiTe sub(1.5)S sub(1.5) show an in-gap surface Dirac point, the former of which has been predicted to show nonzero weak topological invariants such as (1; 111); thus belonging to a different topological class than BiTe sub(1.5)S sub(1.5). The measured band structure presented here will be a valuable guide for interpreting transport, thermoelectric, and thermopower measurements on these compounds. The unique surface band topology observed in these compounds contributes towards identifying designer materials with desired flexibility needed for thermoelectric and spintronic device fabrication.
The least absolute shrinkage and selection operator (Lasso) estimation of regression coefficients can be expressed as Bayesian posterior mode estimation of the regression coefficients under various ...hierarchical modeling schemes. A Bayesian hierarchical model requires hyper prior distributions. The regression coefficients are parameters of interest. The normal distribution assigned to each regression coefficient is a prior distribution. The variance parameter in the normal prior distribution is further assigned a hyper prior distribution so that the variance parameter can be estimated from the data. We developed an expectation-maximization (EM) algorithm to estimate the variance parameter of the prior distribution for each regression coefficient. Performance of the EM algorithm was evaluated through simulation study and real data analysis. We found that the Jeffreys' hyper prior for the variance component usually performs well with regard to generating the desired sparseness of the regression model. The EM algorithm can handle not only the usual regression models but it also conveniently deals with linear models in which predictors are defined as classification variables. In the context of quantitative trait loci (QTL) mapping, this new EM algorithm can estimate both genotypic values and QTL effects expressed as linear contrasts of the genotypic values.
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