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Privacy policies are critical for helping individuals make decisions on the usage of information systems. However, as a common language phenomenon, ambiguity occurs pervasively in privacy policies and largely impedes their usefulness. The existing research focuses on the identification of individual vague words or sentences, without considering the context of documents, which may cause a significant amount of false vagueness. Our goal is to automatically detect the potential false vagueness and the related supporting evidence, which illustrates or explains the vagueness, and therefore probably assist in alleviating the vagueness. We firstly analyze the public manual annotations and define four common patterns of false vagueness and three types of supporting evidence. Then we propose the approach of the F·vague-Detector to automatically detect the supporting evidence and then locate the corresponding potential false vagueness. According to our analysis, about 29–39% of individual vague sentences have at least one clarifying sentence in the documents, and experiments show good performance of our approach, with recall of 66.98–67.95%, precision of 70.59–94.85%, and F 1 of 69.24–78.51% on the potential false vagueness detection. Detecting the vagueness of isolated sentences without considering their context within the whole document would bring about one-third potential false vagueness, and our approach can detect this potential false vagueness and the alleviating evidence effectively. [ABSTRACT FROM AUTHOR]

The overwhelming foreground contamination hinders the accurate detection of the 21-cm signal of neutral hydrogen during the Epoch of Reionization (EoR). Among various foreground components, the Galactic free–free emission is less studied, so that its impact on the EoR observations remains unclear. In this work, we employ the observed H α intensity map with the correction of dust absorption and scattering, the simfast21 software, and the latest SKA1-Low layout configuration to simulate the SKA 'observed' images of Galactic free–free emission and the EoR signal. By calculating the 1D power spectra from the simulated image cubes, we find that the Galactic free–free emission is about 103.5–102.0, 103.0–101.3, and 102.5–101.0 times more luminous than the EoR signal on scales of 0.1 Mpc−1 < k < 2 Mpc−1 in the 116–124, 146–154, and 186–194 MHz frequency bands. We further analyse the 2D power spectra inside the properly defined EoR window and find that the leaked Galactic free–free emission can still cause non-negligible contamination, as the ratios of its power (amplitude squared) to the EoR signal power can reach about 200, 60, and 15 per cent on scales of k ∼ 1.2 Mpc−1 in three frequency bands, respectively. Therefore, we conclude that the Galactic free–free emission, as a severe contaminating foreground component, needs to be carefully treated in the forthcoming deep EoR observations. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed at exploring a new tooth development evaluation method for age assessment and investigating the dynamic alteration and potential trend of tooth development by orthopantomograms (OPGs), in order to provide references for tooth development prediction and forensic purpose.Materials and Methods: A total of 132 OPGs of children aged 3-8 years were collected. The developmental stages of the permanent mandibular second molar (M2)were evaluated by experienced examiners according to the Nolla method and Mimics software, respectively. Quantitative analysis of the ratio of the radiopaque calcified area to the dental follicle (RCA/DF) in different stages, ages, sexes and quadrants were evaluated and compared via descriptive statistics and Spearman's correlation coefficient analysis.Results: There was a strong, positive correlation between the examiners' evaluation and mimics analysis results. With the age increased, the Nolla stage of M2 observed by OPGs increased, and the RCA/DF showed increased trends both in males and females. There were significant differences of the RCA/DF of the M2 at various ages. The tooth calcification development of female was 9.08% earlier than that of male between 3 and 8 years old. However, teeth of male seemed to develop faster than that of female during this period. There was no significant difference between left and right quadrant either according to the Nolla stage or RCA/DF.Conclusions: The RCA/DF value obtained from OPGs of the developmental mandibular second permanent molars could be used as a reliable indicator for tooth maturity and age estimation in children aged 3-8 years.Clinical Relevance: Age assessment based on radiographs is considered as a reliable and efficient indicator for judging different types of malocclusion, making suitable orthodontic treatment plan, deciding the extraction time of retained deciduous teeth in clinic practice. [ABSTRACT FROM AUTHOR]

Cross-level requirement trace links (i.e., links between high-level requirements (HLRs) and low-level requirements (LLRs)) record the top-down decomposition process of requirements and support various development and management activities (e.g., requirement validation). Undoubtedly, updating trace links synchronously with requirement changes is critical for their constant availability. However, large-scale open-source software that is rapidly iterative and continually released has numerous requirements that are dynamic. These requirements render timely update of trace links challenging. To address these problems, in this study, a novel deep-learning-based method, deep requirement trace analyzer fusing heterogeneous features (DRAFT), was proposed for updating trace links between various levels of requirements. Considering both the semantic information of requirement text descriptions and the process features based on metadata, trace link data accumulated in the early stage are comprehensively used to train the trace link identification model. Particularly, first, we performed second-phase pre-training for the bidirectional encoder representations from transformers (BERT) language model based on the project document corpus to realize project-related knowledge transfer, which yields superior text embedding. Second, we designed 11 heuristic features based on the requirement metadata in the open-source system. Based on these features and semantic similarity between HLRs and LLRs, we designed a cross-level requirement tracing model for new requirements. The superiority of DRAFT was verified based on the requirement datasets of eight open-source projects. The average F1 and F2 scores of DRAFT were 69.3% and 76.9%, respectively, which were 16.5% and 22.3% higher than baselines. An ablation experiment proved the positive role of two key steps in trace link construction. [ABSTRACT FROM AUTHOR]

Software requirements specification is undoubtedly critical for the whole software life-cycle. Currently, writing software requirements specifications primarily depends on human work. Although massive studies have been proposed to speed up the process via proposing advanced elicitation and analysis techniques, it is still a time-consuming and error-prone task, which needs to take domain knowledge and business information into consideration. In this paper, we propose an approach, named ReqGen, which can provide further assistance by automatically generating natural language requirements specifications based on certain given keywords. Specifically, ReqGen consists of three critical steps. First, keywords-oriented knowledge is selected from the domain ontology and is injected into the basic Unified pre-trained Language Model (UniLM) for domain fine-tuning. Second, a copy mechanism is integrated to ensure the occurrence of keywords in the generated statements. Finally, a requirements-syntax-constrained decoding is designed to close the semantic and syntax distance between the candidate and reference specifications. Experiments on two public datasets from different groups and domains show that ReqGen outperforms six popular natural language generation approaches with respect to the hard constraint of keywords' (phrases') inclusion, BLEU, ROUGE, and syntax compliance. We believe that ReqGen can promote the efficiency and intelligence of specifying software requirements. [ABSTRACT FROM AUTHOR]

Nanocomposites of octavinyl polyhedral oligomeric silsesquioxane (OVPOSS) and functionalized SiO2 were investigated in order to determine the effect of particles on the morphology and mechanical properties of PMMA. The outcome of the study suggested that functionalized SiO2 and octavinylPOSS molecule had different morphology. As proved by X-ray diffraction and transmission electron microscopy analysis, the crystal structure of OVPOSS molecule was significantly different from amorphous aggregates of functionalized SiO2. With the additional particles in the nanocomposites, the sizes of octavinylPOSS and functionalized SiO2 began to reduce. This illustrated that the separation of aggregates led to the formation of irregular POSS molecules and amorphous SiO2 particles varied. Differential scanning calorimetry analysis indicated that PMMA-POSS nanocomposites had a homogeneous system. However, there was a significant phase separation at 3 wt.% SiO2. PMMA-SiO2 nanocomposites displayed lower reinforcing effects than expected, based on the mechanical properties of nanocomposites containing OVPOSS molecules. [ABSTRACT FROM PUBLISHER]

The imbalance between proliferation and apoptosis of fibroblast-like synoviocytes (FLSs) has been the main cause of rheumatoid arthritis (RA) synovial hyperplasia. Our previous study confirmed that the cyclic mechanical stimulation (CMS) inhibited the proliferation of RA FLSs, but the underlying mechanisms are still unclear. This study aimed to investigate these underlying mechanisms. The in vitro cultured human RA FLSs were subjected to CMS (6%, 1.0 Hz). Cell cycle was detected by flow cytometry. The expression of cyclin D1, cyclin E1, CDK-2 and p27 was detected by reverse transcription-polymerase chain reaction (RT-PCR). MTS assay was used to detect cell viability. Cyclooxygenase-2 (COX-2) and prostaglandin E 2 (PGE 2) levels in RA FLSs were detected by western blotting and enzyme-linked immunosorbent assay (ELISA), respectively. The results showed that CMS significantly inhibited the cell cycle transformation of RA FLSs from G1 phase to S phase, which significantly decreased the cell proliferation index. Meanwhile, both cyclin E1 and CDK-2 gene expressions were significantly decreased, p27 gene expression was increased, and no significant change was observed in the expression of cyclin D1. The inhibition of COX-2/PGE 2 pathway in RA FLSs by celecoxib treatment showed no effect on the inhibition of RA FLSs proliferation by CMS. In conclusion, CMS inhibited the proliferation of RA FLSs by modulating the expression of cell cycle-related molecules such as cyclin E1, CDK2 and p27 to arrest cell cycle transformation, which is independent of COX-2/PGE 2 signaling pathway. [ABSTRACT FROM AUTHOR]

In this contribution, creep and relaxation hyper-viscoelastic constitutive models of periodontal ligament (PDL) was proposed to define PDL as a steady state rheology (linear)-nonlinear viscoelastic fluid biomaterial. The physical elements of the hyperelastic spring, non-Newtonian fluid damper and strain gap were proposed. The hyperelastic spring, linear elastic spring, linear viscous damper, stress lock, and strain gap constituted the creep and relaxation models. The qualitative energy analysis was made in the viscoelastic zone between the instantaneous elastic element and the infinite elastic element in the creep and relaxation models. The mechanical behavior of viscoelastic materials is qualitatively unified. The universal static, creep, and relaxation mechanical behaviors of materials were explained from the energy point of view (graphische viscoelastic). After defining a virtual "infinite elastic curve of viscoelastic solid" in the viscoelastic fluid model, the universal creep recovery mechanical behavior was analyzed. The unity of the opposites between viscoelastic solid and viscoelastic fluid was clarified. In addition, A physical thinking of "anchored" was proposed to qualitatively modify the Boltzmann superposition principle. Instantaneous/infinite elastic-plastic-fracture curve, yield curve and fracture curve were defined to distinguish viscoelastic zone and viscoplastic zone. Finally, the unsteady-rheological (nonlinear) behavior of nonlinear viscoelastic fluid materials and the hyper-viscoelastic-plastic behavior of nonlinear viscoelastic solid materials were predicted. • The physical elements of hyperelastic spring, non-Newtonian fluid damper and strain gap are proposed. Creep and relaxation hyper-viscoelastic constitutive models are established. • The mechanical behaviors of linear viscoelastic solids, linear viscoelastic fluids, nonlinear viscoelastic solids and nonlinear viscoelastic fluids are qualitatively unified. • The unity of opposites between viscoelastic solid and viscoelastic fluid. • The Boltzmann superposition principle is qualitatively modification. • Top level design of coupling modeling framework. [ABSTRACT FROM AUTHOR]