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This paper calculates the trade efficiency of China's exports to Africa by considering trade inefficiency factors, such as Chinese aid to Africa and Chinese contracted projects. Based on a stochastic frontier gravity model and data for China's exports to 38 African countries from 2010 to 2020, this study draws the following conclusions. First, trade inefficiencies, such as China's aid and contracted projects, play a positive role in promoting China's export trade to Africa. Second, the efficiency of China's export trade to Africa varies significantly in different regions, among which countries with high export trade efficiency are concentrated in North and South Africa. Third, the trade potential and trade expansion space of China's exports to Africa vary significantly among different product sectors, which provides much space for promoting trade policy. We highlight that China's government should develop differentiated regional trade policies due to regional heterogeneity in terms of export trade efficiency between China and African countries. [ABSTRACT FROM AUTHOR]

In this work, we present a miniaturized wideband rasorber with good angular stability using via-based metal–graphene structure. The rasorber consists of a compact lossy layer, a frequency-selective surface layer, and an air spacer in the middle. The metal–graphene structure in the lossy layer achieves a tiny period due to multiple metal vias connected with meander lines and open stubs. The graphene resistive films printed on the surface by screen-printing technology realize omnidirectional planar resistors for broadband absorption. The 1-dB transmission band of the rasorber is from 7.27 to 8.01 GHz and the 10-dB reflection band is from 2.54 to 8.58 GHz. Due to its miniaturized unit cell, both the transmission and absorption performance is stable with a large-angle incident wave. The ultra-miniaturized rasorber is fabricated and measured, which demonstrates a wide bandwidth of 108.6% and a small period of 0.05 λ L with great angular stability, making it a good candidate for bi-station stealth radome applications. [ABSTRACT FROM AUTHOR]

Recent years have seen an increase number of studies on spherical video-based virtual reality (SVVR) in education.However, the impact of SVVR on learning performance remains unclear and cannot be simply generalized from traditional VR-based education. The purpose of this study was to examine the overall effects of SVVR on cognitive and non-cognitive learning outcomes and to explore a set of moderating variables in student, technology, pedagogy, and methodology aspects. The meta-analysis examined 33 studies from 31 articles that compare SVVR to other instructional conditions. All analyzed articles were published between 2018 and 2021, and were sourced from ERIC, the Web of Science, Scopus, and Google scholar. This resulted in 27 independent effect sizes on cognitive outcomes and 23 independent effect sizes on non-cognitive outcomes. Overall, we found SVVR had a low-medium and a medium effect on cognitive and non-cognitive learning outcomes, respectively. For cognitive learning outcomes, the effect sizes were significantly moderated by scaffolding type and learning duration. For non-cognitive learning outcomes, the effect sizes were significantly moderated by interaction functionality, learning duration, learner’s stage, research setting, source of SVVR, and scaffolding type. A detailed discussion of the findings and implications for teaching and learning with SVVR were provided. [ABSTRACT FROM AUTHOR]

Metamaterial absorbers (MMAs) that absorb electromagnetic waves among an ultra-broad frequency band have attracted great attention in military and civilian applications. In this paper, an ultra-broadband and highly-efficient MMA is presented. The unit cell of the proposed MMA was constructed with two cross-placed stand-up gradient impedance graphene films, which play a key role in improving impedance matching. Considering the trade-off between absorbing performance and processing complexity, in our design, we adopted the stand-up graphene films that have a gradient with three orders of magnitude in total. The simulated results of the proposed absorber show an ultra-broadband absorption (absorptivity > 90%) from 1.8 GHz to 66.7 GHz and a highly-efficient absorption (absorptivity > 97%) in the range of 2–21.7 GHz and 39.6–57 GHz. The field analysis was adopted to explain the mechanism of the proposed absorber. To validate this design, a prototype of 20 × 20 units was processed and assembled. The graphene films were processed with graphene conductive ink using screen print technology. The measured results are in good agreement with the simulated ones. The proposed absorber may find potential applications in the field of stealth technologies and electromagnetic interference. [ABSTRACT FROM AUTHOR]

Cold damage is one of the most important environmental factors influencing crop growth, development, and production. In this study, we generated a pair of near-isogenic lines (NILs), Towada and ZL31, and Towada showed more cold sensitivity than ZL31 in the rice seedling stage. To explore the transcriptional regulation mechanism and the reason for phenotypic divergence of the two lines in response to cold stress, an in-depth comparative transcriptome study under cold stress was carried out. Our analysis uncovered that rapid and high-amplitude transcriptional reprogramming occurred in the early stage of cold treatment. GO enrichment and KEGG pathway analysis indicated that genes of the response to stress, environmental adaptation, signal transduction, metabolism, photosynthesis, and the MAPK signaling pathway might form the main part of the engine for transcriptional reprogramming in response to cold stress. Furthermore, we identified four core genes, OsWRKY24, OsCAT2, OsJAZ9, and OsRR6, that were potential candidates affecting the cold sensitivity of Towada and ZL31. Genome re-sequencing analysis between the two lines revealed that only OsWRKY24 contained sequence variations which may change its transcript abundance. Our study not only provides novel insights into the cold-related transcriptional reprogramming process, but also highlights the potential candidates involved in cold stress. [ABSTRACT FROM AUTHOR]

In this article, we present a novel design method to achieve optically transparent reflectarrays (RAs) with fine metal line (FML) structure. With this design method, an RA element with a peak return loss of 2.8 dB and a phase variation of 360° is achieved during 12.5–14.5 GHz. Compared with the reported transparent RAs, we first realize wide phase variation, high transparency and low return loss simultaneously. The proposed element is composed of FML pattern, quartz glass substrate, and indium tin oxide (ITO) ground. The FML pattern consists of a metal cross and a folded square ring with a linewidth of 50 $\mu $ m made by a photolithographic process. For verification, three $20 \times 20$ -element RAs with pencil beam and orbital angular momentum (OAM) beam have been arranged, simulated, fabricated, and measured. The measured results agree well with the simulations. The measured optical transmittance of all prototypes is greater than 82% at any position. The proposed FML structure greatly improves the transmittance and has potential for the applications in transparent communication devices. [ABSTRACT FROM AUTHOR]

By using defect measures, we prove the existence of partially regular weak solutions to the stationary Navier-Stokes equations with external force f ∈ L loc q ∩ L 3 / 2 , q > 3 in general open subdomains of R 6 . These weak solutions satisfy certain local energy estimates and we estimate the size of their singular sets in terms of Hausdorff measures. We also prove the defect measures vanish under a smallness condition, in contrast to the nonstationary Navier-Stokes equations in R 4 × [ 0 , ∞ [ . [ABSTRACT FROM AUTHOR]

Grain chalkiness reduces the quality of rice (Oryza sativa) and is a highly undesirable trait for breeding and marketing. However, the underlying molecular cause of chalkiness remains largely unknown. Here, we cloned the F-box gene WHITE-CORE RATE 1 (WCR1), which negatively regulates grain chalkiness and improves grain quality in rice. A functional A/G variation in the promoter region of WCR1 generates the alleles WCR1A and WCR1G , which originated from tropical japonica and wild rice Oryza rufipogon , respectively. OsDOF17 is a transcriptional activator that binds to the AAAAG cis-element in the WCR1A promoter. WCR1 positively affects the transcription of the metallothionein gene MT2b and interacts with MT2b to inhibit its 26S proteasome-mediated degradation, leading to decreased reactive oxygen species production and delayed programmed cell death in rice endosperm. This, in turn, leads to reduced chalkiness. Our findings uncover a molecular mechanism underlying rice chalkiness and identify the promising natural variant WCR1A , with application potential for rice breeding. [ABSTRACT FROM AUTHOR]

In this communication, we propose glide-symmetric double-layer (D-L) spoof surface plasmon polaritons (SSPPs) structures for controlling the field confinement of SSPPs to achieve antenna beam manipulation with a large frequency-scanning angle. By changing the shape of the glide-symmetric D-L SSPPs, we can control the electric field confinement of the SSPPs to emerge symmetric or asymmetric distribution. Hence, the proposed SSPPs structure can produce electromagnetic (EM) leakage on both sides or single side, furtherly achieving dual-beam (D-B) or single-beam (S-B) radiation. Two SSPPs antennas with dual beams and single beam are designed, fabricated, and measured. Both the D-B antenna and S-B antenna operate from 9 to 24 GHz. Within the working band, the D-B antenna accomplishes 134.3° (−90° to +44.3°) beam-scanning angle with the realized gain of 8.03–12.17 dBi, while the S-B antenna achieves 119° (−77.9° to 41.1°) beam-scanning angle with 10.31–14.24 dBi realized gain. The simulated and experimental results verified the beam manipulation and large frequency-scanning angle in antenna design. [ABSTRACT FROM AUTHOR]

A novel synthesis method based on transversal coupling matrix for the parallel‐scheme filtering antenna with high out‐of‐band selectivity is proposed. The filtering antenna consists of three resonant radiation elements that are connected to a common feed point. By adopting the parallel scheme, the design of a third‐order filtering antenna can be decomposed into three first‐order sub filtering antennas. Each resonant antenna element can be separately designed and little adjustment is needed after combining these elements. Given a specification with up to two radiation nulls, the corresponding parameters of the three elements can be synthesized using the coupling matrix theory based on transversal topology. A practical filtering antenna centered at 5.74 GHz with the bandwidth of 410 MHz (7.2%) and two radiation nulls at 5.43 GHz and 6.13 GHz is fabricated. The measurements show the gain of 7.5 dBi and out‐of‐band suppression more than 30 dB at both passband sides can be achieved within the total size of 1.208λ0 × 1.725λ0 × 0.024λ0, where λ0 is the free space wavelength of the center frequency. [ABSTRACT FROM AUTHOR]

A dual wideband antenna with a large beam steering angle through endfire radiation and frequency scanning radiation in each band is proposed for the first time. The antenna utilizes a double-layer (D-L) spoof surface plasmon polaritons (SSPPs) structure which exhibits stronger field confinement and lower cutoff frequency than the single-layer (S-L) SSPPs structure. The modulated D-L SSPPs structure can excite the space harmonic distributing in the fast-wave region and retains transmission in the slow-wave region. By combing the modulated D-L SSPPs waveguide and the Vivaldi radiator, both the slow-wave radiation (endfire mode) and the fast-wave radiation (frequency scanning mode) can be aroused in the two operating bands. An example antenna is designed and fabricated. In the slow-wave range from 3 to 9 GHz, the antenna works in the endfire mode with the beam direction of 90° and the realized gain varying from 3.55 to 8.24 dBi. Within the fast waveband from 13 to 34 GHz, the antenna operates in the frequency-scanning mode, accomplishing beam scanning from −90° to ±42.5° with the realized gain of 9.45–15.67 dBi. Thus, the proposed dual-band antenna can achieve two operating bands and two radiation modes, which offers a 180° beam-changing angle in total. [ABSTRACT FROM AUTHOR]

Designing a lesson plan for science, technology, engineering, and mathematics (STEM) is an important skill in STEM teaching. It requires systematic training that begins at the pre-service stage. It is particularly difficult to help pre-service teachers (PSTs) develop their ability to design an integrated STEM learning unit that features competence-oriented, interdisciplinary, student-centered, authentic, and collaborative learning. Through three rounds of iterative design, this study aimed to develop a technology-enhanced STEM PST training solution. Each round of design sought to address practical issues that had been identified during the implementation of the training in the previous stage. When developing the program, we articulated five principles that guided our design, the final outcome of which was an online teacher training environment integrated with a visual learning design tool and a learning analytics function. We discuss the implications of our research in terms of recommended design principles for STEM PST training, and we suggest directions for future research on the cultivation of STEM learning design expertise. [ABSTRACT FROM AUTHOR]

Chalkiness is one of the key determinants of rice quality and is a highly undesirable trait for breeding and marketing. In this study, qWCR7, a major quantitative trait locus (QTL) of white-core rate (WCR), was genetically validated using a BC3F2 segregation population and further fine mapped using a near isogenic line (NIL) population, of which both were derived from a cross between the donor parent DL208 and the recurrent parent ZS97. qWCR7 was finally narrowed to a genomic interval of ~ 68 kb, containing seven annotated genes. Among those, two genes displayed markedly different expression levels in endosperm of NILs. Transcriptome analysis showed that the synthesis and accumulation of metabolites played a key role in chalkiness formation. The contents of storage components and expression levels of related genes were detected, suggesting that starch and storage protein were closely related to white-core trait. Our findings have laid the foundation of map-based cloning of qWCR7, which may have potential value in quality improvement during rice breeding. [ABSTRACT FROM AUTHOR]

Proteins are fundamental molecules that mediate diverse biological processes, and protein design can shed light on the molecular mechanisms underlying their biological functions. Huang and colleagues have developed a sequence-independent statistical model for de novo protein design using neural networks (NNs) to learn the distribution of backbone structures with minimal side-chain information. [ABSTRACT FROM AUTHOR]

In this communication, a high-gain substrate-integrated waveguide (SIW) filtering patch antenna with low H-plane cross-polarization (cross-pol) and controllable radiation nulls is proposed. The antenna is composed of a radiation patch integrated with three pairs of shorting pins and a single layer SIW cavity with two transverse slots. The shorting pins loaded on the patch can improve the gain and reduce the H-plane cross-pol of the antenna. The long slot on the middle layer can not only split the TE110-mode resonator into two half-mode resonators but also generate magnetic coupling between half-mode resonators and the patch. Another short slot achieves mixed electric and magnetic coupling between the left half-mode resonator and the patch that introducing controllable radiation nulls to improve the selectivity. By adjusting the parameters of the short slot, the positions of two radiation nulls can be easily controlled. Finally, one prototype filtering antenna is fabricated and measured for demonstration. Experimental results show that the proposed SIW filtering antenna achieves a high gain of 9 dBi with only one radiator and has the merit of high-frequency selectivity as well as low H-plane cross-pol of lower than −43 dB. [ABSTRACT FROM AUTHOR]

We show that for any given solenoidal initial data in L 2 and any solenoidal external force in L loc q ⋂ L 3 / 2 with q > 3 , there exist partially regular weak solutions of the Navier–Stokes equations in R 4 × [ 0 , ∞ [ which satisfy certain local energy inequalities and whose singular sets have a locally finite 2-dimensional parabolic Hausdorff measure. With the help of a parabolic concentration-compactness theorem we are able to overcome the possible lack of compactness arising in the spatially 4-dimensional setting by using defect measures, which we then incorporate into the partial regularity theory. [ABSTRACT FROM AUTHOR]

A novel compact MIMO dual‐mode filtering antenna array with wide bandwidth, high selectivity and good isolation is proposed. The filtering antenna unit consists of a patch radiator at the top layer coupled with a high‐order dual‐mode filter at the bottom layer through a rectangular slot in the middle ground layer. The fourth‐order filter adopts two E‐shape dual‐mode resonators to achieve wide bandwidth and high selectivity. A pair of filtering antenna units form a MIMO array with a distance of 0.2λg by using three interdigital lines in the middle to enhance the port isolation. Finally, a 1 × 2 MIMO filtering antenna array operating at 2.45 GHz is designed and fabricated, which shows wide fractional bandwidth of 24.5%, sharp skirt slope with a pair of radiation nulls, smooth realized gain of 4.5 dBi as well as high isolation more than 20 dB. [ABSTRACT FROM AUTHOR]

In this article, a novel class of dynamically tunable filtering attenuators with high selectivity and continuously tunable attenuation is proposed through the comprehensive design of graphene sandwiched structure (GSS), microstrip line, and half-mode substrate integrated waveguide (HMSIW). The GSSs are loaded on microstrip resonators to reduce the resonance intensity, which results in a valid attenuation in the passband. A co-design method of GSS, microstrip resonator, and HMSIW coupling structure based on the equivalent circuit model is proposed to minimize the impact of graphene on the selectivity of filtering attenuator. A transmission zero located on the upper band is also introduced to enhance the selectivity. By varying the bias voltage on GSSs, a controllable attenuation from 1.7 to 8.4 dB can be obtained over the operating bandwidth centering at 1.72 GHz while preserving good selectivity. It is worth mentioning that the out-of-band suppression of the proposed filtering attenuator is also reduced from 40 to 50 dB. Another tunable filtering attenuator based on microstrip short-ended resonators is also designed to verify the method. Finally, a prototype is fabricated and measured and the measured results are in good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

A novel dual-polarized frequency-selective rasorber (FSR) using an omnidirectional planar resistor based on graphene flake is presented in this article. The FSR exhibits a low-loss transmission window above an absorption band. It consists of a lossy layer and a lossless bandpass frequency-selective surface (FSS). In the lossy layer, a central symmetric graphene-metal hybrid structure is formed by connecting four metal strip-based resonant circuits with a square graphene flake. A low insertion loss transmission band is obtained by removing the resistance out of the parallel resonant circuits. Moreover, equivalent circuits are utilized to demonstrate the working mechanism. The proposed FSR exhibits a good absorption performance from 8.15 to 13.8 GHz, and a low insertion loss of 0.15 dB obtained at 16 GHz. Finally, a prototype FSR is fabricated and good agreement between the simulated and the measured results is obtained. The FSR has further advantages of avoiding the process of welding multiple lumped resistors per unit, thereby greatly reducing the number of lumped components and improving the planar integration of the structure. [ABSTRACT FROM AUTHOR]

With the availability of low‐cost high‐quality head‐mounted displays (HMDs) since 2013, there is a growing body of literature investigating the impact of immersive virtual reality (IVR) technology on education. This meta‐analysis aims to synthesize the findings on the overall effects of IVR using HMDs compared to less immersive desktop virtual reality (DVR) and other traditional means of instruction. A systematic search was carried out on the literature published between 2013 and 2019. Thirty‐five randomized controlled trials (RCTs) or quasi‐experimental studies were identified. We conducted an analysis using the random effects model (REM) to calculate the pooled effect size. The studies were also coded to examine the moderating effects of their characteristics, such as learner stage, learning domain, learning application type, testing format, control group treatment and learning duration, on the outcome measure. The results showed that IVR using HMDs is more effective than non‐immersive learning approaches with a small effect size (ES = 0.24). The key findings of the moderator analysis were that HMDs have a greater impact (a) on K‐12 learners; (b) in the fields of science education and specific abilities development; (c) when offering simulation or virtual world representations; and (d) when compared with lectures or real‐world practices. The meta‐analysis also suggested that HMDs can improve both knowledge and skill development, and maintain the learning effect over time. [ABSTRACT FROM AUTHOR]

A novel compact and self‐packaging inline pseudoelliptic filter is proposed. The proposed filter exploits controllable mixed electric and magnetic coupling using substrate integrated suspended line (SISL) technology. Based on a synchronously tuned coupled resonator circuit with parallel LC resonant tank and admittance inverters, general formulas for extracting electric and magnetic coupling coefficients are derived. Meanwhile, a basic mixed coupled SISL resonator pair is investigated and a systematic design procedure of a second‐order mixed coupled SISL filter is also given. Two prototypes of the second‐order filter with one transmission zero (TZ) at either upper or lower stopband are designed, which is corresponding to either magnetic or electric coupling dominant case. Furthermore, for asynchronously tuned coupled resonator cases, an inline third‐order pseudoelliptic SISL filter characterized by symmetric TZs is designed, fabricated, and measured for validation. The simulated and measured results show a good agreement with the synthesized ones. [ABSTRACT FROM AUTHOR]

In this communication, a millimeter-wave (MMW) pattern reconfigurable Vivaldi antenna utilizing graphene-based tunable resistor is proposed. First, a modified Vivaldi antenna with high front-to-back ratio is achieved by equal proportion slotting on the ground patch. Then, a pattern reconfigurable antenna consisting of a pair of back-to-back modified Vivaldi antennas with two graphene nanoplate pads symmetrically loaded on the feed line is proposed to realize dynamical manipulation of gain. By applying bias voltage from 0 to 4 V, the resistance of the graphene pad can be gradually reduced from 200 to $20~\Omega $. Two slots located on the ground allow two graphene pads to be dc interruption for independent resistance control. By varying the resistance of two graphene pads, the radiation pattern of Vivaldi antenna can be manipulated from two opposite beams to a single beam. Finally, a prototype antenna centering at 30 GHz with a bandwidth of 16.6% is fabricated and measured, which realizes reconfigurable radiation beams at 90° and/or 270° with three states. [ABSTRACT FROM AUTHOR]

In the microwave region, graphene material usually has a relatively high resistivity, which limits its application potential in electromagnetic shielding and radiation. Meanwhile, conventional carbon materials are difficult to meet the requirement of electronic devices and electromagnetic shielding in terms of thickness reduction and flexibility. Here, a flexible multilayer graphene film (MGF) with high conductivity and small thickness is achieved by high temperature thermal treatment of GO films and subsequence compression rolling. We experimentally study the EMI shielding performance of the MGF with a thickness of 27 μm, which shows high shielding effectiveness (SE) of 70 dB from 2.6 GHz to 40 GHz. Making use of its high conductivity of 1.13 × 106 S/m and low sheet resistance of 32.7 mΩ/□, a MGF based multi-beam millimeter wave antenna array with average gain of 15.07 dBi and large beam scanning range of 120°is realized for the first time. All the measurements indicate that the flexible, low thickness, low-density and highly conductive multi-layer graphene film have great potential in the application of electromagnetic shielding, electromagnetic conduction and electromagnetic radiation devices. Image 1 [ABSTRACT FROM AUTHOR]

A compact wideband balun filtering quasi‐Yagi antenna with high selectivity is proposed. It consists of a quasi‐Yagi antenna integrated with a multilayer balun filter. The quasi‐Yagi antenna is composed of a bow‐tie driver coupled with a director on the top layer, and a ground reflector on the bottom layer. The fourth‐order balun filter has two stepped impedance resonators (SIRs) on the top layer, and two SIRs on the middle layer, which helps improve the frequency selectivity and bandwidth. Moreover, it has two differential ports to feed the quasi‐Yagi antenna. The filtering antenna centered at 2.5 GHz with a wide bandwidth of 22.8% and a pair of transmission zeros is designed and fabricated, which shows a stable radiation pattern with maximum gain of 5.5 dBi and high selectivity. [ABSTRACT FROM AUTHOR]

Despite growing awareness of the importance of incorporating integrated science, technology, engineering and mathematics (STEM) learning into K‐12 education, formal classroom implementation still faces obstacles. Teachers lack the knowledge and skills, especially design‐thinking competence, required to design an interdisciplinary STEM curriculum. The goal of this study was to investigate different scaffolding modes that may influence the design‐thinking competence development of STEM teachers. Twenty‐four preservice teachers participated in this study, which was carried out in an online STEM preservice teacher training environment. The participants were assigned to six groups of two cohorts. Each group designed a STEM learning module. To support their online design meetings, the three groups from the static scaffolding cohort (SSC) received pre‐defined guiding questions, while the other three groups from the adaptive scaffolding cohort (ASC) received contingent scaffolding from a human tutor. The Log data on the participants' conversations in the design meetings were collected and analysed using the epistemic network analysis (ENA) approach. The results revealed that the SSC and ASC had divergent design‐thinking development trajectories and established distinct design‐thinking patterns. Conversation analysis of the two cohorts confirmed the findings of the ENA analysis and provided evidence that the two scaffolding modes can help address challenges to collaborative STEM learning design and cultivate design‐thinking competence from different perspectives. Practitioner NotesWhat is already known about this topic Integrated and interdisciplinary STEM curriculum should be incorporated into K‐12 education.Teachers lack the design‐thinking competence required to design an integrated and interdisciplinary STEM curriculum.What this paper adds Static scaffolding and adaptive scaffolding help STEM preservice teachers to develop process‐oriented and result‐oriented design‐thinking patterns, respectively.STEM preservice teachers present divergent design‐thinking development trajectories during collaborative STEM learning design under these two scaffolding modes.Implications for practice and/or policy Integrated STEM learning design should leverage the complexity in the design process and creativity in the design solutions.Different scaffolding modes can complement each other in support of design‐thinking competence development in collaborative STEM learning design practice. [ABSTRACT FROM AUTHOR]

Computational thinking (CT), the ability to devise computational solutions for real‐life problems, has received growing attention from both educators and researchers. To better improve university students' CT competence, collaborative programming is regarded as an effective learning approach. However, how novice programmers develop CT competence through collaborative problem solving remains unclear. This study adopted an innovative approach, quantitative ethnography, to analyze the collaborative programming activities of a high‐performing and a low‐performing team. Both the discourse analysis and epistemic network models revealed that across concepts, practices, and identity, the high‐performing team exhibited CT that was systematic, whereas the CT of the low‐performing team was characterized by tinkering or guess‐and‐check approaches. However, the low‐performing group's CT development trajectory ultimately converged towards the high‐performing group's. This study thus improves understanding of how novices learn CT, and it illustrates a useful method for modeling CT based in authentic problem‐solving contexts. Lay Description: What is already known about this topic: Computational thinking competence includes computational concepts, computational practices, and computational perspectives.Collaborative programming has the potential to foster computational thinking competence development.What this paper adds: The low‐performing student group adopted a bottom‐up perspective at the beginning but transformed to a top‐down approach by the end.The low‐performing group's computational thinking development trajectory had convergent evolution towards the high‐performing group's trajectory.Implications for practice and/or policy: Computational thinking competence can be developed in collaborative contexts even when students begin with a bottom‐up approach.Computational thinking should go beyond the cognitive development of computational concepts to connect computational practice and computational identity.Quantitative ethnography approach has potential to model computational thinking competence in collaborative programming context. [ABSTRACT FROM AUTHOR]

A compact tunable cavity filter based on double‐layer suspended stripline resonator (DSSLR) is proposed. The DSSLR consists of a thin substrate suspended in an air‐filled cavity, a stepped impedance resonator loaded with interdigital capacitor on the top layer of the substrate, and a parallel‐plate capacitor series with a varactor at the bottom layer. The multiple capacitors not only achieve compact size by large capacitive loading, but also broaden the tuning range with a small capacitance variation of varactor. The internal coupling of two DSLLRs increases with the height of the inductive stub while decreases with the distance between two resonators. A fifth‐order wideband tunable cavity filter using a common bias voltage is designed, fabricated, and measured, which has a tunable frequency range of 67 MHz, constant bandwidth of 64 ± 7 MHz, low return loss of 15 dB, and high suppression of more than 40 dB. [ABSTRACT FROM AUTHOR]

With the continuous deployment of ICT in K‐12 education, strong access but weak uptake has become the greatest challenge for ICT implementation in schools. As the pioneer of China's K‐12 educational reform, Shanghai draws our attention in terms of the critical factors and the underlying mechanism of ICT transformation in K‐12 schools. The study used questionnaire survey data collected from 2894 Shanghai teachers (971 primary, 990 middle and 933 high school teachers) to investigate the relationships between government ICT policy, school principal e‐leadership, ICT implementation in schools, teacher attitudes towards ICT and pedagogical change and changes in student learning. The structural equation modelling results revealed a significant influence of e‐leadership by school principals on ICT transformation in schools, confirming the critical role of e‐leadership in ICT transformation model. In addition, the higher the school stage, the more personal rather than organisational factors affected the changes in teaching and learning. The findings imply a profound sociocultural and technological dilemma due to the pressure of getting into college and risk‐taking in ICT‐related educational transformation. The study contributes to our knowledge in terms of a more nuanced ICT transformation mechanism between school stages. [ABSTRACT FROM AUTHOR]

Concept mapping has been widely used to foster meaningful learning and support the communication of complex ideas. With a focus on conceptual understanding, traditional concept mapping is found to be inadequate in supporting problem solving particularly in eliciting and representing the complex process of applying knowledge to practice. In this study, a computer-based cognitive-mapping approach was used to extend traditional concept mapping by allowing learners to represent the problem-solving process and the underlying knowledge in a visual format. By representing ideas both verbally and pictorially, the cognitive mapping approach has a high potential to foster effective thinking and reflection in problem-solving contexts. This study examined the effects of the computer-based cognitive-mapping approach by comparing it to a note-taking approach that represents ideas in verbal text only. Forty-nine senior year medical students participated in the study. The experimental group used the cognitive-mapping approach, while the control group used a note-taking approach, to articulate complex thinking and actions when working with simulated clinical diagnostic problems in a computer-based learning environment. The results show the promising effects of the cognitive-mapping approach on improving students' problem-solving performance, subject-matter knowledge, and intrinsic motivation to learn with complex problems. [ABSTRACT FROM AUTHOR]

Automated segmentation of abdominal organs and tumors in medical images is a challenging yet essential task in medical image analysis. Deep learning has shown excellent performance in many medical image segmentation tasks, but most prior efforts were fragmented, addressing individual organ and tumor segmentation tasks with specialized networks. To tackle the challenges of abdominal organ and tumor segmentation using partially labeled datasets, we introduce Re-parameterizing Mixture-of-Diverse-Experts (RepMode) to abdominal organ and tumor segmentation. Within the RepMode framework, the Mixture-of-Diverse-Experts (MoDE) block forms the foundation, learning generalized parameters applicable across all tasks. We seamlessly integrate the MoDE block into a U-shaped network with dynamic heads, addressing multi-scale challenges by dynamically combining experts with varying receptive fields for each organ and tumor. Our framework incorporates task encoding in both the encoder–decoder section and the segmentation head, enabling the network to adapt throughout the entire system based on task-related information. We evaluate our approach on the multi-organ and tumor segmentation (MOTS) dataset. Experiments show that DoDRepNet outperforms previous methods, including multi-head networks and single-network approaches, giving a highly competitive performance compared with the original single network with dynamic heads. DoDRepNet offers a promising approach to address the complexities of abdominal organ and tumor segmentation using partially labeled datasets, enhancing segmentation accuracy and robustness. [ABSTRACT FROM AUTHOR]

Acute vascular injury occurs in a number of important clinical contexts, including spontaneous disease-related events (e.g. plaque rupture, thrombosis) and therapeutic interventions such as angioplasty, stenting, or bypass surgery. Endothelial cell (EC) disruption exposes the underlying matrix, leading to a rapid deposition of platelets, coagulation proteins, and leukocytes. A thrombo-inflammatory response ensues characterized by leukocyte recruitment, vascular smooth muscle cell (VSMC) activation, and the elaboration of cytokines, reactive oxygen species and growth factors within the vessel wall. A resolution phase of vascular injury may be described in which leukocyte efflux, clearance of debris, and re-endothelialization occurs. VSMC migration and proliferation leads to the development of a thickened neointima that may lead to lumen compromise. Subsequent remodeling involves matrix protein deposition, and return of EC and VSMC to quiescence. Recent studies suggest that specialized pro-resolving lipid mediators (SPM) modulate key aspects of this response, and may constitute an endogenous homeostatic pathway in the vasculature. SPM exert direct effects on vascular cells that counteract inflammatory signals, reduce leukocyte adhesion, and inhibit VSMC migration and proliferation. These effects appear to be largely G-protein coupled receptor-dependent. Across a range of animal models of vascular injury, including balloon angioplasty, bypass grafting, and experimental aneurysm formation, SPM accelerate repair and reduce lesion formation. With bioactivity in the pM-nM range, a lack of discernible cytotoxicity, and a spectrum of vasculo-protective properties, SPM represent a novel class of vascular therapeutics. This review summarizes current research in this field, including a consideration of critical next steps and challenges in translation. [ABSTRACT FROM AUTHOR]

Mutations in the N-terminus of MED12 protein occur at high frequency in uterine leiomyomas and breast fibroepithelial tumours, and are frequently found in chronic lymphocytic leukaemia ( CLL). MED12 mutations have been previously linked to aberrant Cyclin C- CDK8 kinase activity, but the exact oncogenic function in CLL is unknown. Here, we characterized MED12 mutations in CLL and identified recurrent mutations in 13 out of 188 CLL patients (6·9%), which clustered in the N-terminus. MED12 mutations were associated with unmutated IGHV ( P = 0·024). Protein analysis of NOTCH1 in primary CLL samples revealed increased levels of NOTCH1 intracellular domain ( NICD), the active form of NOTCH1, in the context of MED12 mutations. We found evidence that NICD is the target of Cyclin C- CDK8 kinase using a specific CDK8 inhibitor. In line with these findings, MED12 mutations were mutually exclusive to mutations in NOTCH1 in CLL, based on a meta-analysis of 1429 CLL patients ( P = 0·011). Our results suggest that MED12 mutations may contribute to CLL pathogenesis by activating NOTCH signalling. [ABSTRACT FROM AUTHOR]

A tunable dual-band filtering power divider with constant bandwidth and high selectivity is proposed, which incorporates a wideband power divider with two tunable dual-band filters. The filter provides a tunable dual-mode dual-band filtering response, and realizes a 90° phase shift to replace the middle quarter wavelength transmission line. As the bias voltage increases, the lower band increases from 1.1 to 1.5 GHz with a constant bandwidth of 40 MHz, while the higher band remains at 2.17 GHz with a fixed bandwidth of 60 MHz. During the wide tuning range, the return loss and isolation are always >15 dB, with a high selectivity due to multiple transmission zeros. [ABSTRACT FROM AUTHOR]

Anaplastic thyroid cancer (ATC) is a rare but highly aggressive kind of thyroid cancer. Various therapeutic methods have been considered for the treatment of ATC, but its prognosis remains poor. With the advent of the nanomedicine era, the use of nanotechnology has been introduced in the treatment of various cancers and has shown great potential and broad prospects in ATC treatment. The current review meticulously describes and summarizes the research progress of various nanomedicine-based therapeutic methods of ATC, including chemotherapy, differentiation therapy, radioiodine therapy, gene therapy, targeted therapy, photothermal therapy, and combination therapy. Furthermore, potential future challenges and opportunities for the currently developed nanomedicines for ATC treatment are discussed. As far as we know, there are few reviews focusing on the nanomedicine of ATC therapy, and it is believed that this review will generate widespread interest from researchers in a variety of fields to further expedite preclinical research and clinical translation of ATC nanomedicines. [ABSTRACT FROM AUTHOR]

With the rapid development of underground space utilization, the excavation of new tunnels with ultra-shallow under crossing buildings using the drilling and blasting method is gradually increasing. The blasting vibration will undoubtedly affect the surrounding buildings. Reducing the impact of blasting vibration on ground buildings has become an important technical challenge faced by tunnel blasting technicians. The inlet end of the Xi'an-Chengdu High-Speed Railway Xiannvyan Tunnel passes below a village through an ultra-shallow buried section; as a result, blasting vibration control is a major concern. A design scheme for a 0.6 m footage in tunnel was proposed and verified through field tests. A 0.8 m footage scheme and 1.8 m footage millisecond interference vibration reduction scheme were proposed, respectively. Based on the HHT analysis, by comparing the surface vibration velocities and instantaneous energy obtained from the millisecond delay detonation of cutting holes and the detonation of different charging schemes, we found that the free surface, mass of single dynamite charges, and tunnel burial depth had significant influences on the surface vibration. [ABSTRACT FROM AUTHOR]

Problem solving is considered a fundamental human skill. However, large-scale assessment of problem solving in K-12 education remains a challenging task. Researchers have argued for the development of an enhanced assessment approach through joint effort from multiple disciplines. In this study, a three-stage approach based on an evidence-centered design framework is proposed to analyze problem-solving behavior, abilities, and performance. The approach is applied to assess the online problem solving of 554 students in a Shanghai primary school. The study reveals four clusters with distinctive problem-solving behavior, abilities, and performance. The findings of this approach also corroborate the results of the Programme for International Student Assessment of Shanghai students’ problem-solving performance. The implications and limitations of this study are also discussed. [ABSTRACT FROM PUBLISHER]

• We first reported the somatic and germline genetic aberrations in pNPC. • Patients with pNPC exhibited high level of PD-L1 expression. • Our results provide a deeper understanding of molecular genetics of pNPC. While a number of genetic and epigenetic events contributing to adult nasopharyngeal carcinomas (aNPC) development has been established, the scarcity of pediatric nasopharyngeal carcinoma (pNPC) hinders the understanding of the biology of the disease and rational treatment approach. We aim to identify the molecular characteristics of pNPC. pNPC primary tumors with paired blood samples were collected and sequenced using whole-exome sequencing. Samples were collected from four tertiary academic medical centers in China. A total of 30 patients (25 male and 5 female) with pathologically confirmed NPC under the age of 20 were enrolled. Several genes such as C9orf84 (20 %), ZFHX4 (16.7 %), ZC3H6 (16.7 %), RBM38 (16.7 %) were frequently mutated in pNPC. Copy number analysis revealed highly recurring gain/amplification of the HLA class II genes at 6p21.32 (63.3 %) and losses of TOLLIP at 11p15.5 (20 %). Recurrent NUTM1 (16.7 %) fusion variants were found for the first time with pNPC. We also investigated germline genomic signatures and showed 8 of 30 (26.7 %) of the pNPC patients carrying germline pathogenic and/or likely pathogenic variants in known cancer-predisposing genes. Multi-dimensional comparison suggested that pNPC might exhibit distinct genomic profile compared to aNPC. In addition, pNPC exhibited significantly elevated level of PD-L1 expression than aNPC (percent of patients with >50 % PD-L1 expression: 92.0 % vs 32.1 %), suggesting high possibility of benefit from immunotherapy. Our results provide the first insight into the molecular basis of pNPC, and might offer novel targets and therapeutic approaches such as immunotherapy for this rare disease. [ABSTRACT FROM AUTHOR]

Objectives: While a number of genetic and epigenetic events contributing to adult nasopharyngeal carcinomas (aNPC) development has been established, the scarcity of pediatric nasopharyngeal carcinoma (pNPC) hinders the understanding of the biology of the disease and rational treatment approach. We aim to identify the molecular characteristics of pNPC.Materials and Methods: pNPC primary tumors with paired blood samples were collected and sequenced using whole-exome sequencing. Samples were collected from four tertiary academic medical centers in China. A total of 30 patients (25 male and 5 female) with pathologically confirmed NPC under the age of 20 were enrolled.Results: Several genes such as C9orf84 (20 %), ZFHX4 (16.7 %), ZC3H6 (16.7 %), RBM38 (16.7 %) were frequently mutated in pNPC. Copy number analysis revealed highly recurring gain/amplification of the HLA class II genes at 6p21.32 (63.3 %) and losses of TOLLIP at 11p15.5 (20 %). Recurrent NUTM1 (16.7 %) fusion variants were found for the first time with pNPC. We also investigated germline genomic signatures and showed 8 of 30 (26.7 %) of the pNPC patients carrying germline pathogenic and/or likely pathogenic variants in known cancer-predisposing genes. Multi-dimensional comparison suggested that pNPC might exhibit distinct genomic profile compared to aNPC. In addition, pNPC exhibited significantly elevated level of PD-L1 expression than aNPC (percent of patients with >50 % PD-L1 expression: 92.0 % vs 32.1 %), suggesting high possibility of benefit from immunotherapy.Conclusion: Our results provide the first insight into the molecular basis of pNPC, and might offer novel targets and therapeutic approaches such as immunotherapy for this rare disease. [ABSTRACT FROM AUTHOR]

A Ti:sapphire laser at 729 nm is frequency stabilized to an ultra-stable ultra-low thermal expansion coefficient (ULE) cavity by means of Pound-Drever-Hall method. An acousto-optic modulator is used as the fast frequency feedback component. 1 Hz linewidth and 2 × 10−15 frequency stability at 1-100 s are characterized by optical beating with a separated Fabry-Perot cavity stabilized diode laser. Compared to the universal method that the error signal feedback to inject current of a diode laser, this scheme is demonstrated to be simple and also effective for linewidth narrowing. The temperature of zero coefficient of the thermal expansion of the ULE cavity is measured with the help of a femto-second frequency comb. And the performance of the laser is well defined by locking it to the unperturbed clock transition line-center of 4 S1/2-3 D5/2 clock transition of a single laser cooled 40Ca+ ion. A Fourier-transform limited resonance of 6 Hz (Δv/v = 1.5 × 10−14) is observed. This laser is also used as the local oscillator for the comparison experiment of two 40Ca+ ion optical clocks and improves the stability of comparison for an order of magnitude better than the previous results. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel hexa-mode stub-loaded ring resonator is proposed. Due to its symmetry, even-odd-mode method is applied to analyze the resonance characteristics. All the six modes equivalent circuits are quarter-wavelength uniform impedance resonators (UIRs). Stub-stub coupling is introduced to split two identical modes and produce two transmission zeros (TZs). Then a triband bandpass filter operating at 1.5, 2.4, and 3.5 GHz is designed using the proposed resonator. The center frequency and bandwidth of each passband can be independently controlled. Two extra TZs were generated by the hook-shape feedlines and a relatively wide stopband was achieved. Finally, the designed filter was fabricated and measured, and the measured results have good agreement with the simulated ones. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2005-2008, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT A fourth-order multimode wideband diplexer with high selectivity and compact size is presented in this article. The open- or short-ended stub-loaded hairpin resonator (SLHR) is utilized to split one resonant mode to even-mode and odd-mode. A pair of SLHRs splits the two modes to four modes and also introduces two transmission zeros for each channel due to the mixed coupling. Using two kinds of SLHRs at the two filtering channel, a compact multimode wideband diplexer with center frequencies at 2.1 GHz/2.5 GHz and fractional bandwidths of 10.5%/8.5% are designed and fabricated. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1096-1099, 2015 [ABSTRACT FROM AUTHOR]

Purpose: Angiotensin I-converting enzyme (ACE) is crucial in the renin–angiotensin–aldosterone system. ACE insertion/deletion (I/D) polymorphism is a common genetic variation of this gene and is associated with several disease phenotypes. However, the results of published studies on the influence of this polymorphism on renal transplantation are inconsistent. Therefore, a meta-analysis was performed to evaluate the association between ACE I/D polymorphism and prognosis of kidney transplantation. Methods: A meta-analysis was performed based on 21 case–control studies from 12 publications (1497 cases and 2029 controls) and 10 studies with quantitative values from 5 publications (814 patients). Pooled odds ratios (ORs) and weighted mean differences (WMDs) with their corresponding 95% confidence intervals (CIs) were used to estimate associations. Results: ACE I/D polymorphism was found to be associated with acute rejection (AR) in genotypes DD+ID versus II (OR = 1.62, 95% CI = 1.14–2.29) and with serum creatinine concentration after renal transplantation in genotypes DD versus ID (WMD = 13.12, 95% CI = 8.09–18.16). Stratified analysis revealed that recipients transplanted within a year had higher serum creatinine concentrations in the DD versus ID model. No significant association was found between hypertension and ACE I/D polymorphism. Conclusion: ACE I/D polymorphism is associated with AR and allograft function after kidney transplantation. [ABSTRACT FROM AUTHOR]

Early hospital readmission among vascular surgery patients is a focus of Medicare’s new reimbursement structure. We aim to identify factors associated with 30-day readmission after lower extremity interventions to treat peripheral artery disease (PAD). Retrospective analysis of 174 consecutive patients discharged from the vascular surgery service between January 1, 2011, and July 31, 2012, after procedures for lower extremity PAD was performed. Of 174 patients, 37 were readmitted within 30 days of discharge. There were no significant differences in baseline characteristics between the readmitted and the nonreadmitted groups. In a multivariate logistic regression model, urgent operation and advanced chronic kidney disease (CKD) were associated with increased risk of 30-day readmission. The most common reasons for readmission were infection of the surgical site or index limb (18 of 37), followed by unresolved limb symptoms (13 of 37). The 30-day readmission is frequent after lower extremity interventions to treat PAD. Urgent operative intervention and advanced CKD appear to be risk factors for early hospital readmission. [ABSTRACT FROM AUTHOR]

ABSTRACT A tunable dual-mode dual-band filter composed of varactor-loaded folded square loop resonator is presented. A pair of the resonators is mirror coupled to form the higher band, while two varactors with the same bias are symmetrically loaded at the corner of each loop, splitting dual modes and form the tunable lower band. As the bias voltage increases, the lower band frequency increases from 1.1 GHz to 1.5 GHz with a constant bandwidth, while the higher band one remains at 2.1 GHz. The dual-mode effect and source-load coupling introduce multiple transmission zeros that effectively improves the out-of-band selectivity. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:283-285, 2017 [ABSTRACT FROM AUTHOR]

Abstract: Learning through problem solving has been widely adopted as an effective learning paradigm in challenging domains such as medical education. For effective learning through practical experience, problem solving and knowledge construction should be highly integrated and reciprocally reinforcing. However, both knowledge construction and problem solving are complex cognitive processes, which cannot be easily captured and mastered. Temporal problem-solving experience can be forgotten, and knowledge embedded in problem-solving experience may not be transferable to new problems. This study aimed to address the challenge via proposing a computer-based learning environment, where a visualization-based cognitive tool was designed to make thinking and learning in a problem context visible and to connect problem-solving and knowledge-construction activities throughout the learning process. An online learning program using the proposed learning environment was delivered to thirty-five students from two medical schools. The design of the proposed learning environment and its effects on problem-based learning are examined with implications for further studies. [Copyright &y& Elsevier]

Through genome mining, we identified a gene encoding a putative serine protease of the thermitase subgroup of subtilases (EC 3.4.21.66) in the thermophilic bacterium Coprothermobacter proteolyticus. The gene was functionally expressed in Escherichia coli, and the enzyme, which we called proteolysin, was purified to near homogeneity from crude cell lysate by a single heat treatment step. Proteolysin has a broad pH tolerance and is active at temperatures of up to 80°C. In addition, the enzyme shows good activity and stability in the presence of organic solvents, detergents, and dithiothreitol, and it remains active in 6 M guanidinium hydrochloride. Based on its stability and activity profile, proteolysin can be an excellent candidate for applications where resistance to harsh process conditions is required. [ABSTRACT FROM AUTHOR]

Abstract: Three novel triphenylamine (TPA) derivatives having perfluorinated cyclopentenyl and benzo[b]thiophene unit are obtained from 4-bromo-N,N-diphenyl-2-methylbenzo[b]thiophen-5-amine. The new compounds are expected to find their use in thin film devices as charge transport materials and host organic light-emitting materials. It is found that the new compounds show relatively strong fluorescence either in solution or in solid state, and are amorphous due to a special conformation which is elucidated by the fine structure of 19F NMR. Molecular structure and properties of these compounds is characterized by 1H NMR, 13C NMR (broadband decoupled), ESI–HRMS, elemental analysis and thermal analysis (DSC). Fluorescent quantum yield in solution is measured using 9,10-diphenylanthrancene (DPA) as standard fluorescent substance. [Copyright &y& Elsevier]

Ammonia lyases (AL) and aminomutases (AM) are emerging in green synthetic routes to chiral amines and an AL is being explored as an enzyme therapeutic for treating phenylketonuria and cancer. Although the restricted substrate range of the wild-type enzymes limits their widespread application, the non-reliance on external cofactors and direct functionalization of an olefinic bond make ammonia lyases attractive biocatalysts for use in the synthesis of natural and non-natural amino acids, including β-amino acids. The approach of combining structure-guided enzyme engineering with efficient mutant library screening has extended the synthetic scope of these enzymes in recent years and has resolved important mechanistic issues for AMs and ALs, including those containing the MIO (4-methylideneimidazole-5-one) internal cofactor. [ABSTRACT FROM AUTHOR]

Click to switch: A novel family of azobenzenes containing residues needed for aqueous Staudinger–Bertozzi ligation to azides was designed (see scheme). The resulting photochromes show stable and reversible switching behavior in water, with a photostationary state (PSS) of up to 95:5 cis/trans. Applications in model systems include the modification of azide‐bearing surfaces and proteins. [ABSTRACT FROM AUTHOR]

Klicken und schalten: Eine neue Familie von Azobenzolen wurde entwickelt, die geeignete Substituenten für die wässrige Staudinger ‐ Bertozzi ‐ Ligation an Azide enthalten. Die entstehenden Photochrome zeigen ein stabiles und reversibles Schaltverhalten in Wasser, mit einem photostationären Zustand (PSS) bis zu 95:5 cis/trans. Anwendungen in Modellsystemen umfassen die Modifikation azidierter Oberflächen und Proteine. [ABSTRACT FROM AUTHOR]