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On single-cell RNA-sequencing data, we consider the problem of assigning cells to known cell types, assuming that the identities of cell-type-specific marker genes are given but their exact expression levels are unavailable, that is, without using a reference dataset. Based on an observation that the expected over-expression of marker genes is often absent in a nonnegligible proportion of cells, we develop a method called scSorter. scSorter allows marker genes to express at a low level and borrows information from the expression of non-marker genes. On both simulated and real data, scSorter shows much higher power compared to existing methods.

Tarski’s first-order axiom system E2 for Euclidean geometry is notable for its completeness and decidability. However, the Pythagorean theorem—either in its modern algebraic form a2+b2=c2 or in Euclid’s Elements—cannot be directly expressed in E2, since neither distance nor area is a primitive notion in the language of E2. In this paper, we introduce an alternative axiom system Ed in a two-sorted language, which takes a two-place distance function d as the only geometric primitive. We also present a conservative extension Eda of it, which also incorporates a three-place angle function a, both formulated strictly within first-order logic. The system Ed has two distinctive features: it is simple (with a single geometric primitive) and it is quantitative. Numerical distance can be directly expressed in this language. The Axiom of Similarity plays a central role in Ed, effectively killing two birds with one stone: it provides a rigorous foundation for the theory of proportion and similarity, and it implies Euclid’s Parallel Postulate (EPP). The Axiom of Similarity can be viewed as a quantitative formulation of EPP. The Pythagorean theorem and other quantitative results from similarity theory can be directly expressed in the languages of Ed and Eda, motivating the name Quantitative Euclidean Geometry. The traditional analytic geometry can be united under synthetic geometry in Ed. Namely, analytic geometry is not treated as a model of Ed, but rather, its statements can be expressed as first-order formal sentences in the language of Ed. The system Ed is shown to be consistent, complete, and decidable. Finally, we extend the theories to hyperbolic geometry and Euclidean geometry in higher dimensions.

One of the most debated problems in the foundations of the special relativity theory is the role of conventionality. A common belief is that the Lorentz transformation is correct but the Galilean transformation is wrong (only approximately correct in low speed limit). It is another common belief that the Galilean transformation is incompatible with Maxwell equations. However, the “principle of general covariance” in general relativity makes any spacetime coordinate transformation equally valid. This includes the Galilean transformation as well. This renders a new paradox. This new paradox is resolved with the argument that the Galilean transformation is equivalent to the Lorentz transformation. The resolution of this new paradox also provides the most straightforward resolution of an older paradox which is due to Selleri in (Found Phys Lett 10:73–83, 1997). I also present a consistent electrodynamics formulation including Maxwell equations and electromagnetic wave equations under the Galilean transformation, in the exact form for any high speed, rather than in low speed approximation. Electrodynamics in rotating reference frames is rarely addressed in textbooks. The presented formulation of electrodynamics under the Galilean transformation even works well in rotating frames if we replace the constant velocity v with v = ω×r. This provides a practical tool for applications of electrodynamics in rotating frames. When electrodynamics is concerned, between two inertial reference frames, both Galilean and Lorentz transformations are equally valid, but the Lorentz transformation is more convenient. In rotating frames, although the Galilean electrodynamics does not seem convenient, it could be the most convenient formulation compared with other transformations, due to the intrinsic complex nature of the problem.

Atmospheric sulfate levels are thought to determine the pH of small aerosol particles. Thermodynamic analysis of field aerosol data reveals that fine particles remain acidic in the southeastern United States despite large sulfate reductions. Particle acidity affects aerosol concentrations, chemical composition and toxicity. Sulfate is often the main acid component of aerosols, and largely determines the acidity of fine particles under 2.5 μm in diameter, PM 2.5 . Over the past 15 years, atmospheric sulfate concentrations in the southeastern United States have decreased by 70%, whereas ammonia concentrations have been steady. Similar trends are occurring in many regions globally. Aerosol ammonium nitrate concentrations were assumed to increase to compensate for decreasing sulfate, which would result from increasing neutrality. Here we use observed gas and aerosol composition, humidity, and temperature data collected at a rural southeastern US site in June and July 2013 (ref.  1 ), and a thermodynamic model that predicts pH and the gas–particle equilibrium concentrations of inorganic species from the observations to show that PM 2.5 at the site is acidic. pH buffering by partitioning of ammonia between the gas and particle phases produced a relatively constant particle pH of 0–2 throughout the 15 years of decreasing atmospheric sulfate concentrations, and little change in particle ammonium nitrate concentrations. We conclude that the reductions in aerosol acidity widely anticipated from sulfur reductions, and expected acidity-related health and climate benefits, are unlikely to occur until atmospheric sulfate concentrations reach near pre-anthropogenic levels.

Ruthenium (Ru) is widely recognized as a low-cost alternative to iridium as anode electrocatalyst in proton-exchange membrane water electrolyzers (PEMWE). However, the reported Ru-based catalysts usually only operate within tens of hours in PEMWE because of their intrinsically high reactivity of lattice oxygen that leads to irrepressible Ru leaching and structural collapse. Herein, we report a design concept by employing large-sized and acid-resistant lattice lead (Pb) as a second element to induce a pinning effect for effectively narrowing the moving channels of oxygen atoms, thereby lowering the reactivity of lattice oxygen in Ru oxides. The Pb-RuO 2 catalyst presents a low overpotential of 188 ± 2 mV at 10 mA cm −2 and can sustain for over 1100 h in an acid medium with a negligible degradation rate of 19 μV h −1 . Particularly, the Pb-RuO 2 -based PEMWE can operate for more than 250 h at 500 mA cm −2 with a low degradation rate of only 17 μV h −1 . Experimental and theoretical calculation results reveal that Ru-O covalency is reduced due to the unique 6 s −2 p −4 d orbital hybridization, which increases the loss energy of lattice oxygen and suppresses the over-oxidation of Ru for improved long-term stability in PEMWE. Developing robust catalysts for proton-exchange membrane water electrolyzers is essential for industrial applications. Here, the authors report a Pb-RuO 2 catalyst that uses large-sized Pb to reduce the reactivity of lattice oxygen, enhancing stability and allowing it to operate for over 1100 h.

Ligand effect, induced by charge transfer between catalytic surface and substrate in core/shell structure, was widely proved to benefit Pt-catalyzed oxygen reduction reaction by tuning the position of d -band center of Pt theoretically. However, ligand effect is always convoluted by strain effect in real core/shell nanostructure; therefore, it remains experimentally unknown whether and how much the ligand effect solely contributes electrocatalytic activity improvements. Herein, we report precise synthesis of a kind of Pd 3 Ru 1 /Pt core/shell nanoplates with exclusive ligand effect for oxygen reduction reaction. Layer-by-layer growth of Pt overlayers onto Pd 3 Ru 1 nanoplates can guarantee no lattice mismatch between core and shell because the well-designed Pd 3 Ru 1 has the same lattice parameters as Pt. Electron transfer, due to the exclusive ligand effect, from Pd 3 Ru 1 to Pt leads to a downshift of d -band center of Pt. The optimal Pd 3 Ru 1 /Pt 1-2L nanoplates achieve excellent activity and stability for oxygen reduction reaction in alkaline/acid electrolyte. Deconvoluting and quantitating ligand effect from the typical strain-ligand effects in a real catalytic structure remains challenging. Here, the authors report a core/shell catalyst model to quantitate how much ligand effect solely contributes to electrocatalytic performance through experimental design.

In some regions, reducing aerosol ammonium nitrate (NH4NO3) concentrations may substantially improve air quality. This can be accomplished by reductions in precursor emissions, such as nitrogen oxides (NOx) to lower nitric acid (HNO3) that partitions to the aerosol, or reductions in ammonia (NH3) to lower particle pH and keep HNO3 in the gas phase. Using the ISORROPIA-II thermodynamic aerosol model and detailed observational data sets, we explore the sensitivity of aerosol NH4NO3 to gas-phase NH3 and NOx controls for a number of contrasting locations, including Europe, the United States, and China. NOx control is always effective, whereas the aerosol response to NH3 control is highly nonlinear and only becomes effective at a thermodynamic sweet spot. The analysis provides a conceptual framework and fundamental evaluation on the relative value of NOx versus NH3 control and demonstrates the relevance of pH as an air quality parameter. We find that, regardless of the locations examined, it is only when ambient particle pH drops below an approximate critical value of 3 (slightly higher in warm and slightly lower in cold seasons) that NH3 reduction leads to an effective response in PM2.5 mass. The required amount of NH3 reduction to reach the critical pH and efficiently decrease NH4NO3 at different sites is assessed. Owing to the linkage between NH3 emissions and agricultural productivity, the substantial NH3 reduction required in some locations may not be feasible. Finally, controlling NH3 emissions to increase aerosol acidity and evaporate NH4NO3 will have other effects, beyond reduction of PM2.5 NH4NO3, such as increasing aerosol toxicity and potentially altering the deposition patterns of nitrogen and trace nutrients.

Background The interplay between motivational traits and work values is essential for understanding life satisfaction among Chinese high school English teachers. This study investigates how motivation and teaching work values relate to life satisfaction, situating the research within the unique context of Chinese educators. Methods Participants are Chinese High School English teachers ( N  = 742) who answered a self-reported questionnaire conducted online using a web survey during April-May 2024. The analysis included hypothesis testing using Model 4 of the PROCESS macro for SPSS, which examines both the direct and indirect effects of an independent variable (X) on a dependent variable (Y) through a mediator (M). This model was tested separately for each independent variable: personal mastery, competitive excellence, and motivation anxiety. Results The results indicated that personal mastery is positively associated with life satisfaction, and a significant positive relationship exists between personal mastery and work values. The findings also revealed a positive association between work values and life satisfaction, with mediation analysis showing that work values partially mediate the relationship between personal mastery and life satisfaction. While the direct effect of competitive excellence on life satisfaction was not significant, its indirect effect through work values was significant. Conversely, although the direct effect of motivation anxiety on life satisfaction was significant, the indirect effect through work values was not. Conclusions These results underscore the importance of aligning work environments with educators’ values to enhance their professional performance and overall quality of life. Practical implications include guiding school administrators and policymakers to foster environments that support teachers’ motivational traits and work values, which can lead to improved job satisfaction, reduced stress, and greater retention among educators.

This research sought to examine the impact of electronic portfolio -based writing instruction on the second language writing performance and writing self-efficacy of Chinese English as a foreign language (EFL) learners. A total of 64 participants were divided into two groups, an experimental group (n = 31) and a control group (n = 33). The experimental group was given electronic portfolio-based instruction via Edmodo platform, while the control group received only traditional in-class writing instruction without the use of Edmodo. Two sample IELTS tasks and Writing Self-efficacy scale were administered to collect the quantitative data. Further, semi-structured interviews were carried out with participants in the experimental group to gather qualitative data on their perceptions and experiences with electronic portfolio-based writing instruction. The results of paired samples t-tests and ANCOVAs indicated that electronic portfolio-based writing instruction significantly improved global writing performance and its underlying components, namely content, organization, language use, vocabulary, and mechanics, as well as the writing self-efficacy of Chinese EFL learners. Qualitative results revealed several themes, including increased motivation, improved feedback, enhanced collaboration, improved writing skills, and increased writing self-efficacy. Overall, the study demonstrates that electronic portfolio can be a valuable tool for EFL writing instruction and has a positive impact on writing performance and writing self-efficacy for Chinese EFL learners. Plain Language Summary In this study, we wanted to see how using electronic portfolios in writing instruction would affect Chinese students learning English as a foreign language. We had a total of 64 participants, split into two groups: one group used electronic portfolios through the Edmodo platform, while the other group received traditional in-class writing instruction. We measured their writing performance and self-confidence before and after the study. We also interviewed the participants in the electronic portfolio group to get their thoughts and experiences. The results showed that the electronic portfolio-based instruction significantly improved the students’ overall writing performance and specific aspects like content, organization, language use, vocabulary, and mechanics. It also increased their confidence in their writing abilities. The interviews revealed that the students were more motivated, received better feedback, collaborated more effectively, and felt their writing skills had improved. This study shows that using electronic portfolios can be very helpful for teaching English writing to Chinese students, improving their writing skills and self-confidence.

Compared to the severe winter haze episodes in the North China Plain (NCP), haze pollution during summertime has drawn little public attention. In this study, we present the highly time-resolved chemical composition of submicron particles (PM1) measured in Beijing and Xinxiang in the NCP region during summertime to evaluate the driving factors of aerosol pollution. During the campaign periods (30 June to 27 July 2015, for Beijing and 8 to 25 June 2017, for Xinxiang), the average PM1 concentrations were 35.0 and 64.2 µg m−3 in Beijing and Xinxiang. Pollution episodes characterized with largely enhanced nitrate concentrations were observed at both sites. In contrast to the slightly decreased mass fractions of sulfate, semivolatile oxygenated organic aerosol (SV-OOA), and low-volatility oxygenated organic aerosol (LV-OOA) in PM1, nitrate displayed a significantly enhanced contribution with the aggravation of aerosol pollution, highlighting the importance of nitrate formation as the driving force of haze evolution in summer. Rapid nitrate production mainly occurred after midnight, with a higher formation rate than that of sulfate, SV-OOA, or LV-OOA. Based on observation measurements and thermodynamic modeling, high ammonia emissions in the NCP region favored the high nitrate production in summer. Nighttime nitrate formation through heterogeneous hydrolysis of dinitrogen pentoxide (N2O5) enhanced with the development of haze pollution. In addition, air masses from surrounding polluted areas during haze episodes led to more nitrate production. Finally, atmospheric particulate nitrate data acquired by mass spectrometric techniques from various field campaigns in Asia, Europe, and North America uncovered a higher concentration and higher fraction of nitrate present in China. Although measurements in Beijing during different years demonstrate a decline in the nitrate concentration in recent years, the nitrate contribution in PM1 still remains high. To effectively alleviate particulate matter pollution in summer, our results suggest an urgent need to initiate ammonia emission control measures and further reduce nitrogen oxide emissions over the NCP region.