1,176 research outputs found
The Cultivation of Intercultural Communicative Competence in Senior High School English Teaching—Based on China’s Standards of English Ability
Intercultural communicative competence is a prerequisite for students in senior high school to have a smooth communication with foreigners in the future. This paper discusses the current situation of students’ ICC through questionnaires and then analyzes students’ ICC problems respectively. In doing so, this paper offers some tentative teaching methods and hopes to cultivate students’ intercultural communicative competence under the guidance of the China’s Standards of English Ability
Rank Selection for Non-negative Matrix Factorization
Non-Negative Matrix Factorization (NMF) is a widely used dimension reduction
method that factorizes a non-negative data matrix into two lower dimensional
non-negative matrices: One is the basis or feature matrix which consists of the
variables and the other is the coefficients matrix which is the projections of
data points to the new basis. The features can be interpreted as sub-structures
of the data. The number of sub-structures in the feature matrix is also called
the rank which is the only tuning parameter in NMF. An appropriate rank will
extract the key latent features while minimizing the noise from the original
data. In this paper, we develop a novel rank selection method based on
hypothesis testing, using a deconvolved bootstrap distribution to assess the
significance level accurately despite the large amount of optimization error.
In the simulation section, we compare our method with a rank selection method
based on hypothesis testing using bootstrap distribution without deconvolution,
and with a cross-validated imputation method1. Through simulations, we
demonstrate that our method is not only accurate at estimating the true ranks
for NMF especially when the features are hard to distinguish but also efficient
at computation. When applied to real microbiome data (e.g. OTU data and
functional metagenomic data), our method also shows the ability to extract
interpretable sub-communities in the data
Two new species of the genus Stenus Latreille from China (Coleoptera: Staphylinidae: Steninae)
Two new species of the genus Stenus Latreille (subgenus Stenus s. str.) are described: Stenus (s. str.) affinisecretus, sp. n., from Beijing, and S. (s. str.) guandiensis, sp. n., from Shanxi, China. These two new species were collected in the mountain areas. Important morphological characters, like those of hind wings, 8th and 9th abdominal sternites of male, and the aedeagus are illustrated for the new species. All the types are deposited in the Institute of Zoology, Chinese Academy of Sciences, Beijing
Lie symmetry and exact solution of (2+1)-dimensional generalized Kadomtsev-Petviashvili equation with variable coefficients
The simple direct method is adopted to find Non-Auto-Backlund transformation
for variable coefficient non-linear systems. The (2+1)-dimensional
generalized Kadomtsev-Petviashvili equation with variable coefficients is
used as an example to elucidate the solution procedure, and its symmetry
transformation and exact solutions are obtained
2-[(2-Carboxyphenyl)sulfanyl]acetic acid
The title compound, C9H8O4S, affords a zigzig chain in the crystal structure by intermolecular O—H⋯O hydrogen bonds. The molecular geometry suggests that extensive but not uniform π-electron delocalization is present in the benzene ring and extends over the exocyclic C—S and C—C bonds
[1-(4-Hydroxyphenyl)-1H-tetrazol-5-ylsulfanyl]acetic acid
The title compound, C9H8N4O3S, shows a layer structure constructed from intermolecular O—H⋯O and O—H⋯N hydrogen bonds. Interatomic distances suggest that extensive, but not uniform, π-electron delocalization is present in the tetrazole rings and extends over the exocyclic C—S bond
catena-Poly[[diaqua[(4-tolylsulfanyl)acetato-κO]cadmium(II)]-μ-4,4′-bipyridine-κ2 N:N′]
The title complex, [Cd(C9H9O2S)2(C10H8N2)(H2O)2]n, has a linear chain structure. The central CdII ion is in a slightly disorted octahedral environment, coordinated by two aqua ligands, two (4-tolylsulfanyl)acetate ligands and two bridging 4,4′-bipyridine ligands. The CdII ion lies on a twofold rotation axis. Intermolecular O—H⋯O hydrogen bonds connect adjacent chains, forming a layer structure. An intramolecular O—H⋯O hydrogen bond is also present
Group Contribution Approach To Predict the Refractive Index of Pure Organic Components in Ambient Organic Aerosol
We
introduce and assess a group contribution scheme by which the
refractive index (RI) (λ = 589 nm) of nonabsorbing components
common to secondary organic aerosols can be predicted from the molecular
formula and chemical functionality. The group contribution method
is based on representative values of ratios of the molecular polarizability
and molar volume of different functional groups derived from data
for a training set of 234 compounds. The training set consists of
106 nonaromatic compounds common to atmospheric aerosols, 64 aromatic
compounds, and 64 compounds containing halogens; a separate group
contribution model is provided for each of these three classes of
compound. The resulting predictive model reproduces the RIs of compounds
in the training set with mean errors of ±0.58, ±0.36, and
±0.30% for the nonaromatic, aromatic, and halogen-containing
compounds, respectively. We then evaluate predictions from the group
contribution model for compounds with no previously reported RI, comparing
values with predictions from previous treatments and with measurements
from single aerosol particle experiments. We illustrate how such comparisons
can be used to further refine the predictive model. We suggest that
the accuracy of this model is already sufficient to better constrain
the optical properties of organic aerosol of known composition
Organic component vapor pressures and hygroscopicities of aqueous aerosol measured by optical tweezers
Measurements of the hygroscopic response of aerosol and the particle-to-gas partitioning of semivolatile organic compounds are crucial for providing more accurate descriptions of the compositional and size distributions of atmospheric aerosol. Concurrent measurements of particle size and composition (inferred from refractive index) are reported here using optical tweezers to isolate and probe individual aerosol droplets over extended timeframes. The measurements are shown to allow accurate retrievals of component vapor pressures and hygroscopic response through examining correlated variations in size and composition for binary droplets containing water and a single organic component. Measurements are reported for a homologous series of dicarboxylic acids, maleic acid, citric acid, glycerol, or 1,2,6-hexanetriol. An assessment of the inherent uncertainties in such measurements when measuring only particle size is provided to confirm the value of such a correlational approach. We also show that the method of molar refraction provides an accurate characterization of the compositional dependence of the refractive index of the solutions. In this method, the density of the pure liquid solute is the largest uncertainty and must be either known or inferred from subsaturated measurements with an error of <±2.5% to discriminate between different thermodynamic treatments. (Chemical Equation Presented)
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