Query Processing of Geosocial Data in Location-Based Social Networks

The increasing use of social media and the recent advances in geo-positioning technologies have produced a great amount of geosocial data, consisting of spatial, textual, and social information, to be managed and queried. In this paper, we focus on the issue of query processing by providing a systematic literature review of geosocial data representations, query processing methods, and evaluation approaches published over the last two decades (2000–2020). The result of our analysis shows the categories of geosocial queries proposed by the surveyed studies, the query primitives and the kind of access method used to retrieve the result of the queries, the common evaluation metrics and datasets used to evaluate the performance of the query processing methods, and the main open challenges that should be faced in the near future. Due to the ongoing interest in this research topic, the results of this survey are valuable to many researchers and practitioners by gaining an in-depth understanding of the geosocial querying process and its applications and possible future perspectives.

Open access scientific journals: an analysis of the Directory of Open Access Journals

Introduction. The research aims to analyse the publishers, countries of publication, citation indexes, article processing charges, and their inter-relations, in the journals that make up the Directory of Open Access Journals (DOAJ), a global directory that offers scientific information in immediate and exclusive open access. Method. Bibliographic, quantitative, and inferential study of 9,005 journals in the DOAJ, focusing on publishers, countries of publication, article processing charges, and citation indexes. Analysis. Calculation of absolute and relative frequencies, measurement of central tendency, chi-squared test, and Mann-Whitney U test using the R statistical software (version 3.2.4) with a 95% confidence interval. Results. Brazil is the country with the largest number of titles (10.9%), followed by the United Kingdom, which has a greater number of titles with article processing charges fees averaging US$ 1,474 for those that are DOAJ No Seal and US$ 862 for those that are certified DOAJ Seal. Europe has the greatest number of open access titles (47.6%). The Hindawi Publishing Corporation, Elsevier, De Gruyter Open, BioMed Central, and Springer are the publishers with the greatest number of journals and a higher presence in citation indexes (Journal Citation Reports and SCImago Journal Rank). DOAJ Seal journals are correlated and more likely to have article processing charges fees. Conclusions. In the consolidation of open access journals, commercial publishers and countries with a tradition of scientific publishing continue to gather the majority of journals. Thus, the oligopoly of commercial scientific publishers is maintained.

The Use of a Disposable Umbilical Clamp to Secure an Umbilical Venous Catheter in Neonatal Emergencies—An Experimental Feasibility Study

Recent guidelines recommend the umbilical venous catheter (UVC) as the optimal vascular access method during neonatal resuscitation. In emergencies the UVC securement may be challenging and time-consuming. This experimental study was designed to test the feasibility of new concepts for the UVC securement. Umbilical cord remnants were catheterized with peripheral catheters and secured with disposable umbilical clamps. Three different securement techniques were investigated. Secure 1: the disposable umbilical clamp was closed at the level of the inserted catheter. Secure 2: the clamp was closed at the junction of the catheter and plastic wings. Secure 3: the setting of Secure 2 was combined with an umbilical tape. The main outcomes were the feasibility of fluid administration and the maximum force to release the securement. This study shows that inserting peripheral catheters into the umbilical vein and securing them with disposable umbilical clamps is feasible. Rates of lumen obstruction and the effectiveness of the securement were superior with Secure 2 and 3 compared to Secure 1. This new approach may be a rewarding option for umbilical venous catheterization and securement particularly in low-resource settings and for staff with limited experience in neonatal emergencies. However, although promising, these results need to be confirmed in clinical trials before being introduced into clinical practice.

Approximation of Capacity for Downlink Multi-User System with Combination of Precoding and NOMA Methods

Enhancing performance of downlink MU systems is an attractive and important research for future wireless systems. The non-orthogonal multiple access (NOMA) method was proposed to improve the performance of MU systems. In order to further improve the outage probability (OP) and ergodic capacity (EC) of downlink NOMA MU systems, we propose the combination of precoding and NOMA methods, and then the OP and EC of MU systems with our novel method are derived in scenarios of perfect and imperfect successive interference cancellation (SIC) scheme. Moreover, the closed-form expression of OP and EC for both scenarios is theoretically derived and compared with Monte Carlo simulations. The results show that, the analysis method is accurate, and the proposed combining precoding and NOMA can further enhance the performance of MU systems in comparing with the original orthogonal multiple access method.

First experience of laparoscopic kidney cyst resection by a single access method

We describe the first clinical experience of laparoscopic surgery for renal cyst by a single access. Advantages, disadvantages and prospects of this method are analized.

RDFsim: Similarity-Based Browsing over DBpedia Using Embeddings

Browsing has been the core access method for the Web from its beginning. Analogously, one good practice for publishing data on the Web is to support dereferenceable URIs, to also enable plain web browsing by users. The information about one URI is usually presented through HTML tables (such as DBpedia and Wikidata pages) and graph representations (by using tools such as LODLive and LODMilla). In most cases, for an entity, the user gets all triples that have that entity as subject or as object. However, sometimes the number of triples is numerous. To tackle this issue, and to reveal similarity (and thus facilitate browsing), in this article we introduce an interactive similarity-based browsing system, called RDFsim, that offers “Parallel Browsing”, that is, it enables the user to see and browse not only the original data of the entity in focus, but also the K most similar entities of the focal entity. The similarity of entities is founded on knowledge graph embeddings; however, the indexes that we introduce for enabling real-time interaction do not depend on the particular method for computing similarity. We detail an implementation of the approach over specific subsets of DBpedia (movies, philosophers and others) and we showcase the benefits of the approach. Finally, we report detailed performance results and we describe several use cases of RDFsim.

Coherent Contention Resolution Diversity Slotted ALOHA: An Improved Multiple Access Method for Satellite IoT System

For Beyond 5G/6G system, satellite communication systems become an effective component of the space and terrestrial integrated network. Among typical applications, massive Machine Type of Communication (mMTC) is a promising and challenging application. The demands of low power consumption and light signaling make random access methods as the potential solution. Up to now, contention resolution-based ALOHA methods, such as contention resolution diversity slotted ALOHA (CRDSA), improve the throughput significantly. However, its throughput will meet the inflection point soon with the normalized load increasing since collisionless packets are hardly existing. In fact, the diversity of transmitting packets is not utilized totally. In this paper, an improved random access method, named coherent CRDSA method (C-CRDSA), is proposed. It accumulates replicated packets coherently at receiver and further improve the throughput over CRDSA. Detailed derivations and simulations are given. Simulation results corroborate the effectiveness of the proposed method.

Efficient Access Method for Multi-access Edge Servers in Dynamic Map Systems

Research and development on connected cars equipped with communication functions is being conducted, and dynamic maps are being researched and developed as an information and communication platform for cooperative automatic driving. There is a concern about scalability when dynamic maps are constructed on a cloud server to aggregate a wide range of vehicle information. The problem can be alleviated by deploying edge servers that divide the geographic area where vehicles travel and manage each of them. The IP addresses of the edge servers need to be resolved on the basis of the location information of the moving vehicles. Using TCP improves reliability but reduces efficiency because the vehicles move. In this study, we developed a novel method for accessing edge servers that achieves higher reliability and efficiency by adopting UDP using anycast for transmission from vehicle to edge server and implementing a retransmission function. The effectiveness of this access method was verified by using a vehicle driving simulation.