Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in China and quickly spread globally. In this study, we investigated the ...characteristics of viral shedding from different sites and the neutralizing antibody (NAb) response during the acute and convalescent phases of nine children with COVID-19. SARS-CoV-2 was detected in their nasopharyngeal swabs (9/9, 100%), stool samples (8/9, 89%), and oropharyngeal swabs (3/9, 33%) but was not detected in their serum and urine samples. The median duration of viral shedding detected in nasopharyngeal swabs, oropharyngeal swabs, and stools was 13, 4, and 43 days respectively, and the maximum duration of viral shedding detected from stools was 46 days after discharge. In children, nasopharyngeal swabs appear to be a more sensitive specimen type for the diagnosis of COVID-19 compared with oropharyngeal swabs. Three of eight patients produced NAbs in the acute phase, and NAbs were detected in all eight patients with convalescent sera. The results of this study provide valuable information for the diagnosis and surveillance of COVID-19 and development of SARS-CoV-2 vaccines for use in children.
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•A modified quantitative method was constructed to separate flood events.•Ten flood behavior metrics was used to fully describe flood events and identify flood event classes.•Flood ...events in the Yangtze River basin were clustered into six distinct classes.•Flood event classes showed varying spatial pattern, indication a hindrance to unified flood management.•Meteorological, geographical, and human activities factors were dominant impact factors.
Flood is one of the most devastating natural hazards and is responsible for sizeable social-economic losses and substantial fatalities. Flood events with diverse behavior characteristics vary greatly in spatial patterns and bring great challenges for flood management. In this study, the Peak Over Threshold (POT) approach coupled with an event-start-and-end detecting approach was proposed to separate flood events during 2008 ∼ 2018 across the Yangtze River Basin. Ten flood behavior metrics, comprehensively characterizing magnitude, duration, timing, rate of change, and flood forms of flood events, were used to fully describe flood events and then to identify flood event classes. Subsequently, the spatial heterogeneity of flood events was revealed based on behavior similarity classification of numerous events. Furthermore, a Contribution-Based Impact Factor Analysis (CBIFA) method was constructed to investigate the contributions of natural and anthropogenic factors to flood event variations. Results show that: (1) six flood event classes were identified including long-duration and small-rate-of-change flood events (Class 1, 31.00%), sharp-thin and short-tail flood events (Class 2, 20.58%), sharp-thin and early-peak flood events (Class 3, 5.12%), dwarf-fat flood events (Class 4, 18.37%), small and sharp-thin flood events (Class 5, 4.24%), and conventional events (Class 6, 20.67%). (2) Class 1 and Class 4, characterized by small rate of change, long duration and large magnitude, occurred across the whole Yangtze River Basin and mainly in the Middle-Lower Yangtze plains. Class 2 with small magnitude and short duration was mainly distributed in the Qinghai Tibet Plateau. Class 3, Class 5, and Class 6 mainly occurred in mountainous areas and hills in the middle and upper reaches, wherein Class 3 and Class 5 were characterized by large rate of change and short duration. (3) The meteorological factors were the most important impact factors and explained 30.23%∼68.10% of the total flood event variations, followed by geographical (9.19%∼32.10%), human activities (6.56%∼23.17%), soil (9.19%∼19.34%) and vegetation (2.56%∼5.31%) factors. Identifying the spatial pattern of flood events and their driver factors is a crucial step toward accurate flood prediction and will finally provide essential information for reliable flood management.
The complexation mechanism of gelatin (G) and carboxymethyl cellulose (CMC) and their coacervates formation process were studied as a function of pH and protein (Pr) to polysaccharide (Ps) mixing ...ratio (Pr:Ps). Three different CMCs were chosen (FL9, FH9 and FVH6) and five mixing ratio of 1:1, 6:1, 7:1, 8:1 and 9:1 (w/w), were studied to disclose their individual coacervates transition pattern for zeta potential, turbidity, morphology, size distribution and coacervates yield. The coacervates formation mechanism and stability of formed coacervates were examined using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR), Circular Dichroism (CD), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Coacervates with better morphology, good size distribution and highest yield were observed with G-FL9 at mixing ratio of 7:1 and pH 4.40. The evaluation of coacervates formation mechanism showed that G molecules experienced a conformational change in its secondary structure from a flexible pattern to an ordered poly-proline II (PPII) helix. The vibrations of OH and NH bonds spectra at 3437 and 3449 cm−1, respectively for G/CMC coacervates, shifted to lower wave numbers due to the conformational changes of gelatin and CMC, during the coacervates formation. G/CMC complex coacervates were more thermally stable than individual gelatin. Therefore, these complex coacervates will be able to protect and deliver heat sensitive bioactives and food ingredients.
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•Gelatin and CMC coacervation optimum pH and gelatin to CMC ratio were 4.40 and 7:1.•Gelatin and CMC exhibited conformational changes during coacervates formation.•Gelatin-CMC complex coacervates were thermally stable.
Through placing computation, storage, and communications facilities near the data source, Edge Computing (EC) is anticipated to extend the intelligence from the central cloud to the network edge. The ...Quality of Experience (QoE) of user and energy efficiency of mobile device could be significantly improved through offloading their computation-intensive tasks to the network edge. With the increasing popularity of intelligent devices, tasks offloaded to the edge are becoming more complex, consisting of multiple sub-tasks with data dependency, which are typically modeled as a Directed Acyclic Graph (DAG). The scheduling of DAG tasks is more complex, which has been proved to be NP-hard. Traditional DAG scheduling algorithms developed in non-edge computing scenarios could not be directly applied due to their neglect of: (1) the competition of communication resources; and (2) the rescheduling requirement in case of edge server failure in dynamic edge network environment. In this backdrop, this paper presents a failure-resilient DAG task scheduling algorithm to minimize the response delay experienced by the tasks. After formulating the DAG task scheduling problem, a context-aware greedy task scheduling (CaGTS) algorithm is proposed. Then, to cope with the failure event of edge server, a dependency-aware task rescheduling (DaTR) algorithm is designed. To evaluate the performance of the proposed algorithms, extensive experiments have been conducted on a simulator developed using Python. Experimental results with diverse parameter settings have shown that CaGTS could reduce at least 10.47% average completion time than benchmarks, and DaTR can effectively avoid task scheduling interruption caused by server failure events.
Similar bugs are bugs that require handling of many common code files. Developers can often fix similar bugs with a shorter time and a higher quality since they can focus on fewer code files. ...Therefore, similar bug recommendation is a meaningful task which can improve development efficiency. Rocha et al. propose the first similar bug recommendation system named NextBug. Although NextBug performs better than a start-of-the-art duplicated bug detection technique REP, its performance is not optimal and thus more work is needed to improve its effectiveness. Technically, it is also rather simple as it relies only upon a standard information retrieval technique, i.e., cosine similarity. In the paper, we propose a novel approach to recommend similar bugs. The approach combines a traditional information retrieval technique and a word embedding technique, and takes bug titles and descriptions as well as bug product and component information into consideration. To evaluate the approach, we use datasets from two popular open-source projects, i.e., Eclipse and Mozilla, each of which contains bug reports whose bug ids range from 1,400000. The results show that our approach improves the performance of NextBug statistically significantly and substantially for both projects.
•Measure the ignition delay times of C5H12 and C3H6 under O2/CO2 atmospheres.•The Oxymech3.0 model is developed by updating several important reactions based on the Oxymech2.0 Plus.•Develop a ...detailed model for C1-C5 alkane, C2-C3 olefin under both conventional and oxy-fuel atmospheres.•The chemical effects of CO2 mainly caused by the chaperon effects of CO2 for both n-C5H12 and C3H6.
The combustion chemistry kinetics of fossil fuels under O2/CO2 atmospheres and high pressures attract the attention of researchers, since the pressurized oxy-fuel combustion (POC) is seen as a promising technology for capturing CO2 from thermal power industry and exhaust gas recirculation (EGR) is a promising technology to reduce NOx emissions. N-C5H12 is a representative fuel as gasoline components, and C3H6 is an important intermediate product in the oxidation of n-C5H12. In this study, the ignition delay times of n-C5H12 and C3H6 diluted in CO2 are measured at pressures of 1 and 10 atm under O2/CO2 atmospheres at three equivalence ratios (0.5, 1.0, and 2.0) in a shock tube, respectively. A detailed model named as Oxymech3.0 is developed based on the last version, Oxymech2.0 Plus. The model is evaluated with the experimental results in this work, as well as the ignition delay times of n-C5H12 and C3H6 in conventional atmospheres, the laminar flame speeds of n-C5H12 and C3H6, and the species profiles of n-C5H12. The evaluation results of Oxymech3.0 model are compared with several existing models and show the updating reactions in this work improve the prediction of the n-C5H12 and C3H6 IDTs in O2/CO2 atmospheres. The effects of reactions with CO2 for n-C5H12 and C3H6 are very faint. The chemical effects of CO2 mainly caused by the chaperon effects of CO2 for both n-C5H12 and C3H6. For n-C5H12, the chaperon effects are sourced from the third-body collision reactions 2CH3 (+M) ⇔ C2H6 (+M) (R2652), CH3 + H (+M) ⇔ CH4 (+M) (R2637), and C2H2 + H (+M) ⇔ C2H3 (+M) (R2714) at low pressures, while those from the pressure-dependent reactions H + O2 (+M) ⇔ HO2 (+M) (R2562) and H2O2 (+M) ⇔ 2OH (+M) (R2571) enhance at high pressure. For C3H6, the chaperon effects of CO2 are caused by C3H5-A + CH3 (+M) ⇔ C4H8-1 (+M) (R1456) at low pressure and by H + O2 (+M) ⇔ HO2 (+M) (R2562) when the pressure is higher.
Considering the spatial and temporal correlation of traffic flow data is essential to improve the accuracy of traffic flow prediction. This paper proposes a traffic flow prediction model named Dual ...Spatial Convolution Gated Recurrent Unit (DSC-GRU). In particular, the GRU is embedded with the DSC unit to enable the model to synchronously capture the spatiotemporal dependence. When considering spatial correlation, current prediction models consider only nearest-neighbor spatial features and ignore or simply overlay global spatial features. The DSC unit models the adjacent spatial dependence by the traditional static graph and the global spatial dependence through a novel dependency graph, which is generated by calculating the correlation between nodes based on the correlation coefficient. More than that, the DSC unit quantifies the different contributions of the adjacent and global spatial correlation with a modified gated mechanism. Experimental results based on two real-world datasets show that the DSC-GRU model can effectively capture the spatiotemporal dependence of traffic data. The prediction precision is better than the baseline and state-of-the-art models.
•For the first time prevent the dissolution and reaction loss of boron carbide particles by using carbon-coated boron carbide particles as raw materials in the reaction-bonding of boron carbide by Si ...infiltration.•A ceramic skeleton of the nano-SiC particles-coated and -bonded boron carbide particles and resultant mechanical properties.•In situ reaction to form nano silicon carbide particles in reaction bonded boron carbide composites.
To tackle the dissolution problem of boron carbide particles in silicon infiltration process, carbon-coated boron carbide particles were fabricated for the preparation of the reaction-bonded boron carbide composites. The carbon coating can effectively protect the boron carbide from reacting with liquid Si and their dissolution, thus maintaining the irregular shape of boron carbide particles and preventing the growth of boron carbide particles and reaction formed SiC regions. Furthermore, the nano-SiC particles, originated from the reaction of the carbon coating and the infiltrated Si, uniformly coated on the surfaces of boron carbide particles, thus forming a ceramic skeleton of the nano-SiC particles-coated and -bonded boron carbide particles. The Vickers hardness, flexural strength and fracture toughness of the composites can be increased by 26 %, 45 %, and 37 % respectively, by using carbon-coated boron carbide particles as raw materials.
What do developers search for on the web? Xia, Xin; Bao, Lingfeng; Lo, David ...
Empirical software engineering : an international journal,
12/2017, Letnik:
22, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Developers commonly make use of a web search engine such as Google to locate online resources to improve their productivity. A better understanding of what developers search for could help us ...understand their behaviors and the problems that they meet during the software development process. Unfortunately, we have a limited understanding of what developers frequently search for and of the search tasks that they often find challenging. To address this gap, we collected search queries from 60 developers, surveyed 235 software engineers from more than 21 countries across five continents. In particular, we asked our survey participants to rate the frequency and difficulty of 34 search tasks which are grouped along the following seven dimensions: general search, debugging and bug fixing, programming, third party code reuse, tools, database, and testing. We find that searching for explanations for unknown terminologies, explanations for exceptions/error messages (e.g., HTTP 404), reusable code snippets, solutions to common programming bugs, and suitable third-party libraries/services are the most frequent search tasks that developers perform, while searching for solutions to performance bugs, solutions to multi-threading bugs, public datasets to test newly developed algorithms or systems, reusable code snippets, best industrial practices, database optimization solutions, solutions to security bugs, and solutions to software configuration bugs are the most difficult search tasks that developers consider. Our study sheds light as to why practitioners often perform some of these tasks and why they find some of them to be challenging. We also discuss the implications of our findings to future research in several research areas, e.g., code search engines, domain-specific search engines, and automated generation and refinement of search queries.
Virtual screening of Chemdiv database based on TRPC5 protein structure and the fluorescent calcium flow inhibitory activity detection discovered 2 compounds had low IC50 values against hTRPC5-HEK ...293T cells.
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The transient receptor potential canonical channel 5 (TRPC5), a member of the TRPC family, plays a crucial role in the regulation of various physiological activities and diseases, including those related to the central nervous system, cardiovascular system, kidney, and cancer. As a nonselective cation channel, TRPC5 mainly controls the influx of extracellular Ca2+ into cells, thereby modulating cellular depolarization and intracellular ion concentration. Inhibition of TRPC5 by small molecules presents a promising approach for the treatment of TRPC5-associated diseases. In this study, we conducted a comprehensive virtual screening of more than 1.5 million molecules from the Chemdiv database (https://www.chemdiv.com) to identify potential inhibitors of hTRPC5, utilizing the published structures and binding sites of hTRPC5 as a basis. Lipinski's rule, Veber's rule, PAINS filters, pharmacophore analysis, molecular docking, ADMET evaluation and cluster analysis methods were applied for the screening. From this rigorous screening process, 18 candidates exhibiting higher affinities to hTRPC5 were subsequently evaluated for their inhibitory effects on Ca2+ influx using a fluorescence-based assay. Notably, two molecules, namely SML-1 and SML-13, demonstrated significant inhibition of intracellular Ca2+ levels in hTRPC5-overexpressing HEK 293T cells, with IC50 values of 10.2 μM and 10.3 μM, respectively. These findings highlight SML-1 and SML-13 as potential lead molecules for the development of therapeutics targeting hTRPC5 and its associated physiological activities and diseases.
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