Location- and keyword-based querying of geo-textual data: a survey

With the broad adoption of mobile devices, notably smartphones, keyword-based search for content has seen increasing use by mobile users, who are often interested in content related to their geographical location. We have also witnessed a proliferation of geo-textual content that encompasses both textual and geographical information. Examples include geo-tagged microblog posts, yellow pages, and web pages related to entities with physical locations. Over the past decade, substantial research has been conducted on integrating location into keyword-based querying of geo-textual content in settings where the underlying data is assumed to be either relatively static or is assumed to stream into a system that maintains a set of continuous queries. This paper offers a survey of both the research problems studied and the solutions proposed in these two settings. As such, it aims to offer the reader a first understanding of key concepts and techniques, and it serves as an “index” for researchers who are interested in exploring the concepts and techniques underlying proposed solutions to the querying of geo-textual data.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)Nanyang Technological UniversityThis research was supported in part by MOE Tier-2 Grant MOE2019-T2-2-181, MOE Tier-1 Grant RG114/19, an NTU ACE Grant, and the Singtel Cognitive and Artificial Intelligence Lab for Enterprises (SCALE@NTU), which is a collaboration between Singapore Telecommunications Limited (Singtel) and Nanyang Technological University (NTU) that is funded by the Singapore Government through the Industry Alignment Fund Industry Collaboration Projects Grant, and by the Innovation Fund Denmark centre, DIREC

Speed Ripple Reduction of Direct-Drive PMSM Servo System at Low-Speed Operation Using Virtual Cogging Torque Control Method

This paper presents a virtual cogging torque (VCT) control method to reduce the speed ripple of direct-drive permanent magnet synchronous machine (DD-PMSM) servo system under low-speed conditions. Compared with other factors, at low speeds, the cogging torque is the main factor that deteriorates the drive performance, even induces speed oscillations. Especially in this paper, due to volume limitation, the cogging torque is designed larger than normal one in order to remove the need of brake. Based on the model of PMSM, the cause and effect of the cogging torque are analyzed. Inspired by the characteristic of cogging torque, the VCT control method is proposed and investigated to significantly reduce the speed ripple at low speeds. The main idea of this proposed control method is to produce a proper virtual cogging torque and continuously move the corresponding virtual stable equilibrium point to drive the rotor smoothly. In addition to the principle of this control method, its analysis and implementation are studied as well. Simulation and experimental results from the prototype demonstrate that the proposed control method is correct and valid, and it is simple and effective to smooth the speed at low-speed operations

Reactive Astrocytes in Glial Scar Attract Olfactory Ensheathing Cells Migration by Secreted TNF-α in Spinal Cord Lesion of Rat

BACKGROUND:After spinal cord injury (SCI), the formation of glial scar contributes to the failure of injured adult axons to regenerate past the lesion. Increasing evidence indicates that olfactory ensheathing cells (OECs) implanted into spinal cord are found to migrate into the lesion site and induce axons regeneration beyond glial scar and resumption of functions. However, little is known about the mechanisms of OECs migrating from injection site to glial scar/lesion site. METHODS AND FINDINGS:In the present study, we identified a link between OECs migration and reactive astrocytes in glial scar that was mediated by the tumor necrosis factor-alpha (TNF-alpha). Initially, the Boyden chamber migration assay showed that both glial scar tissue and reactive astrocyte-conditioned medium promoted OECs migration in vitro. Reactive astrocyte-derived TNF-alpha and its type 1 receptor TNFR1 expressed on OECs were identified to be responsible for the promoting effect on OECs migration. TNF-alpha-induced OECs migration was demonstrated depending on activation of the extracellular signal-regulated kinase (ERK) signaling cascades. Furthermore, TNF-alpha secreted by reactive astrocytes in glial scar was also showed to attract OECs migration in a spinal cord hemisection injury model of rat. CONCLUSIONS:These findings showed that TNF-alpha was released by reactive astrocytes in glial scar and attracted OECs migration by interacting with TNFR1 expressed on OECs via regulation of ERK signaling. This migration-attracting effect of reactive astrocytes on OECs may suggest a mechanism for guiding OECs migration into glial scar, which is crucial for OECs-mediated axons regrowth beyond the spinal cord lesion site

Rotor Position Tracking Control for Low Speed Operation of Direct-Drive PMSM Servo System

In this paper, a rotor position tracking control (RPTC) strategy is proposed to effectively reduce the speed fluctuation for a direct-drive permanent magnet synchronous motor (DD-PMSM) servo system operating at low speed with different torque disturbances. In this strategy, considering the derivative relationship between the rotor position and speed, a speed command is converted to a real-time rotor position trajectory, and then a position-current two-loop control with the RPTC controller is proposed based on the internal model method to smoothly track the rotor position. In addition, the parameter design of RPTC controller from the perspectives of robust stability and anti-disturbance capability is investigated as well. Comparative simulation and experimental results demonstrate that, at low speed, the proposed RPTC strategy has a good speed performance for both periodic and non-periodic torque disturbances. Moreover, it enjoys simple implementation for not requiring the precise speed feedback and specific torque disturbance information

Circ-SPG11 knockdown hampers IL-1β-induced osteoarthritis progression via targeting miR-337-3p/ADAMTS5

Abstract Background Osteoarthritis (OA) is responsible for the impotent disability in old people. Circular RNA (circRNA) has been reported to be related to the development of diseases. The lack of research on the role of circRNA spastic paraplegia 11 (circ-SPG11) results in conducting this study. Methods The expression of circ-SPG11, microRNA-337-3p (miR-337-3p), and aggrecanases like a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5) mRNA was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Western blot was used to measure the protein expression of extracellular matrix (ECM) degradation-related markers and ADAMTS5. Ribonuclease R (RNase R) was applied to test the stability of circ-SPG11 in CHON-001 cells. The viability, apoptosis, TNF-α and IL-6 production were determined by cell counting kit-8 (CCK-8) assay, flow cytometry assay, and enzyme-linked immunosorbent assay (ELISA), respectively. Meanwhile, the interaction between miR-337-3p and circ-SPG11 or ADAMTS5 was respectively predicted by Circinteractome or Starbase2.0, which was further verified by dual-luciferase reporter system and RNA binding protein immunoprecipitation (RIP) assay. Results Circ-SPG11 and ADAMTS5 were upregulated and miR-337-3p was downregulated in OA tissues and OA model cells. Circ-SPG11 knockdown allayed interleukin 1β (IL-1β)-induced restraint in viability and promotion in apoptosis, TNF-α, and IL-6 generation and ECM degradation in CHON-001 cells. Anti-miR-337-3p or ADAMTS5 overexpression correspondingly reversed si-circ-SPG11 or miR-337-3p overexpression-mediated facilitation in viability, and inhibition in apoptosis, TNF-α and IL-6 generation and ECM degradation in OA model cells. Moreover, anti-miR-337-3p ameliorated si-circ-SPG11-mediated inhibition in ADAMTS5 mRNA and protein expression in OA model cells. Conclusion Circ-SPG11 facilitated OA development via regulating miR-337-3p/ADAMTS5 axis. This finding might contribute to the improvement of OA therapy

Engineering Raspberry-like Plasmonic Nanoclusters as Tags in Surface-Enhanced Raman Scattering-Based Immunoassays

Surface-enhanced Raman scattering (SERS) is highly attractive with the advantages of non-destructive performance, high specificity, and ultra-sensitivity. However, it is still a great challenge to design SERS tags with strong and undisturbed SERS signals via a simple method for an SERS-based immunoassay. Herein, a simple one-pot method was developed for the fabrication of SERS nanotags with interior reporters located at the nanogaps between plasmonic structures. Benefiting from the reducibility and easy-to-polymerize properties of aniline, Au3+ ions were reduced and grew into small-sized Au nanoparticles with a thin layer of polyaniline (PANI) by using aniline as the reductant. Following the continuous polymerization and the reduction reactions, PANI-coated Au nanoparticles were assembled into a nanocluster with sub 5 nm gaps, and PANI located at these gaps were used as interior reporters in SERS tags. As proof-of-concept, a histidine-tagged antigen was used as the model analyte for the SERS-based immunoassay. The proposed sensing platform showed the response to the histidine-tagged antigen ranging from 0.1 to 1000 ng mL−1 with a detection limit of 0.01 ng mL−1. The remarkable and undisturbed SERS signals make the proposed SERS tags feasible for detections of biomarkers with a low concentration in complex biological samples

Engineering Raspberry-like Plasmonic Nanoclusters as Tags in Surface-Enhanced Raman Scattering-Based Immunoassays

Surface-enhanced Raman scattering (SERS) is highly attractive with the advantages of non-destructive performance, high specificity, and ultra-sensitivity. However, it is still a great challenge to design SERS tags with strong and undisturbed SERS signals via a simple method for an SERS-based immunoassay. Herein, a simple one-pot method was developed for the fabrication of SERS nanotags with interior reporters located at the nanogaps between plasmonic structures. Benefiting from the reducibility and easy-to-polymerize properties of aniline, Au3+ ions were reduced and grew into small-sized Au nanoparticles with a thin layer of polyaniline (PANI) by using aniline as the reductant. Following the continuous polymerization and the reduction reactions, PANI-coated Au nanoparticles were assembled into a nanocluster with sub 5 nm gaps, and PANI located at these gaps were used as interior reporters in SERS tags. As proof-of-concept, a histidine-tagged antigen was used as the model analyte for the SERS-based immunoassay. The proposed sensing platform showed the response to the histidine-tagged antigen ranging from 0.1 to 1000 ng mL−1 with a detection limit of 0.01 ng mL−1. The remarkable and undisturbed SERS signals make the proposed SERS tags feasible for detections of biomarkers with a low concentration in complex biological samples