Recently, the concept of “Smart Cities” has developed considerably with the rise and development of the Internet of Things as new form of sustainable development. Smart cities are based on autonomous ...and distributed infrastructure that includes intelligent information processing and control systems heterogeneous network infrastructure, and ubiquitous sensing involving millions of information sources Due to the continued growth of data volume and number of connected IoT devices, however, issues such as high latency, bandwidth bottlenecks, security and privacy, and scalability arise in the current smart city network architecture. Designing an efficient, secure, and scalable distributed architecture by bringing computational and storage resources closer to endpoints is needed to address the limitations of today’s smart city network. In this paper, we propose a novel hybrid network architecture for the smart city by leveraging the strength of emerging Software Defined Networking and blockchain technologies. To achieve efficiency and address the current limitations, our architecture is divided into two parts: core network and edge network. Through the design of a hybrid architecture, our proposed architecture inherits the strength of both centralized and distributed network architectures. We also propose a Proof-of-Work scheme in our model to ensure security and privacy. To evaluate the feasibility and performance of our proposed model, we simulate our model and evaluate it based on various performance metrics. The result of the evaluation shows the effectiveness of our proposed model.
•We discuss the architectural challenges in the smart city network.•We propose a novel hybrid architecture for the smart city network using SDN and blockchain techniques.•We introduce the PoW scheme for a securely distributed smart city network.
The digitalization and massive adoption of advanced technologies in the automotive industry not only transform the equipment manufacturer's operating mode, but also change the current business ...models. The increased adoption of autonomous cars is expected to disrupt government regulations, manufacturing, insurance, and maintenance services. Moreover, providing integrated, personalized, and on-demand services have shared, connected, and autonomous cars in the smart city for a sustainable ecosystem. To address these issues in this paper, we propose a blockchain-based distributed framework for the automotive industry in the smart city. The proposed framework includes a novel miner node selection algorithm for the blockchain-based distributed network architecture. To evaluate the feasibility of the proposed framework, we simulated the proposed model on a private Ethereum blockchain platform using captured dataset of mined blocks from litecoinpool.org . The simulation results show the proof-of-concept of the proposed model that can be used for wide range of future smart applications.
A distributed denial of service (DDoS) attack is an attempt to partially or completely shut down the targeted server with a flood of internet traffic. The primary aim of this attack is to disrupt ...regular traffic flow to the victim’s server or network. DDoS attacks are volumetric attacks, and non-legacy IoT devices with low security such as webcams, baby monitoring devices and printers are compromised to form a botnet. High traffic from compromised IoT devices is rerouted to servers to disrupt their regular services. DDoS attacks are to an extent covered in the research literature. However, existing research do not discuss all DDoS attacks on general servers and botnet attacks on IoT devices and suggest few detection and mitigation solutions which are limited to addressing attacks on the cloud environment. Existing survey focuses either on the cloud layer or the IoT layer. A complete survey of DDoS attacks for both IoT and the cloud environment is not present in the current literature. Our survey is a comprehensive approach which includes general DDoS attack motivations and specific reasons why attackers prefer IoT devices to launch DDoS attacks. Various attack methods to compromise IoT devices and tools used to deploy botnet-infected IoT devices for DDoS attacks on the cloud layer are presented. A detailed attack classification on IoT devices and the cloud environment is presented considering that IoT devices are first compromised and then used by attackers against their primary targets on the cloud layer. Various state-of-the-art defense measures in the current literature for defense against DDoS attacks are present. Suggestions to implement an essential first line of defense for IoT devices are suggested. Our paper, to the best of our knowledge, is first to provide a holistic study of DDoS attacks from IoT devices to the cloud environment.
Summary Background Adipose-derived stem cells (ADSCs) are a population of pluripotent cells, which have characteristics similar to bone marrow-derived mesenchymal stem cells. Whereas ADSCs have ...potential applications for the repair and regeneration of various damaged tissues, few studies have dealt with the effect of ADSCs on fibroblasts, which play a key role in skin biology. Objective In this study, we investigated the possible roles of ADSCs in skin wound healing process, especially in the aspect of fibroblast activation—proliferation, collagen synthesis and migratory properties. Methods and results ADSCs promoted human dermal fibroblast (HDF) proliferation, not only by cell-to-cell direct contact, which was confirmed by co-culture experiment, but also by paracrine activation through secretory factors, resolved by transwell co-culture and culturing with conditioned medium of ADSCs (ADSC-CM). ADSC-CM enhanced the secretion of type I collagen in HDFs by regulating the mRNA levels of extracellular matrix (ECM) proteins: up-regulation of collagen type I, III and fibronectin and down-regulation of MMP-1. Moreover, ADSC-CM showed stimulatory effect on migration of HDFs in in vitro wound healing models. Additional to those in vitro evidences, wound healing effect of ADSCs was also verified with in vivo animal study, resulted that ADSCs significantly reduced the wound size and accelerated the re-epithelialization from the edge. Conclusion Collectively, these data suggest that ADSC is constitutionally well suited for dermal wound healing and secretory factors derived from ADSCs promote wound healing via HDFs and ADSCs can be used for the treatment of photoaging and wound healing.
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•Spam activities on Facebook are studied.•A novel feature set is introduced to the task of spammer detection on Facebook.•A baseline dataset of Facebook user profiles is ...constructed.•We propose a SapmSpotter framework based on intelligent decision support system.
Facebook is one of the most popular and leading social network services online. With the increasing amount of users on Facebook, the probability of broadcasting spam content on it is also escalating day by day. There are a few existing techniques to combat spam on Facebook. However, due to the public unavailability of critical pieces of Facebook information, like profiles, network information, an unlimited number of posts and more, the existing techniques do not work efficiently for detecting many spammers. In this paper, we propose an efficient spammer detection framework (we called as SpamSpotter) that distinguishes spammers from legitimate users on Facebook. Based on Facebook's recent characteristics, the framework introduces a novel feature set to facilitate spammer detection. We use a baseline dataset from Facebook that included 300 spammers and 700 legitimate user profiles. The baseline dataset contains a set of features for each profile, which are extracted using a novel dataset construction mechanism. In addition, an intelligent decision support system that uses eight different machine learning classifiers on the baseline dataset is designed to distinguish spammers from legitimate users. To evaluate the efficiency and accuracy of our proposed framework, we implemented and compared it with existing frameworks. The evaluation results demonstrate that our proposed framework is accurate and efficient to deliver first-rate performance. It attains a higher accuracy of 0.984 and Mathew correlation coefficient of 0.977.
ABSTRACT
Adipose‐derived stem cells (ADSCs) have been shown to induce wound‐healing effects. Because inflammation near the wound area induces oxygen deficiency, it is interesting to elucidate the ...effect of hypoxia on the function of ADSCs. In this work, we asked: (1) does hypoxia alter the wound‐healing function of ADSCs? and (2) what are the major factors responsible for the alteration in the wound‐healing function? Effect of hypoxia on the proliferation of ADSCs was first examined that hypoxia (2% O2) enhanced the proliferation of ADSCs in either the presence of serum or in the absence of serum. The conditioned medium of ADSCs harvested under hypoxia (hypoCM) significantly promoted collagen synthesis and the migration of human dermal fibroblasts, compared with that in normoxia (norCM). In the animal studies, hypoCM significantly reduced the wound area compared with norCM. Furthermore, mRNA and protein measurements showed that hypoxia up‐regulated growth factors such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF). Inhibition of VEGF and bFGF using neutralizing antibodies reversed the migration of the wounded human dermal fibroblasts and the healing of wounds in animal experiment. Collectively, these results suggest that hypoxia increases the proliferation of ADSCs and enhances the wound‐healing function of ADSCs, at least partly, by up‐regulating the secretion of VEGF and bFGF.
Abstract
Background
Some coronavirus disease 2019 (COVID-19) survivors experience prolonged and varying symptoms, a condition termed post-acute COVID-19 syndrome (PACS). However, the prevalence of ...chronic pulmonary sequelae of PACS during long-term follow-up remains unclear. Several studies have examined this issue and reported heterogeneous results.
Methods
We conducted a systematic review and meta-analysis using a random-effects model to estimate the pooled prevalence of the pulmonary sequelae of COVID-19, as demonstrated by pulmonary function testing (PFT) and chest computed tomography (CT) performed at least 6 months after initial infection. PubMed, Embase, and Cochrane Library databases were searched from January 1, 2020 to December 31, 2021 to identify related studies. We investigated whether the prevalence of pulmonary sequelae decreased over time and attempted to identify the factors associated with their development by performing multiple subgroup and meta-regression analyses.
Results
Of the 18,062 studies identified, 30 met our eligibility criteria. Among these studies, 25 and 22 had follow-up PFT and chest CT data, respectively. The follow-up durations were approximately 6 and 12 months in 18 and 12 studies, respectively. Impaired diffusion capacity was the most common abnormality on PFT (pooled prevalence 35%, 95% confidence interval CI 30–41%) with a prevalence of 39% (95% CI 34–45%) and 31% (95% CI 21–40%) in the 6-month and 12-month follow-up studies, respectively (
P
= 0.115). Restrictive pulmonary dysfunction evident as reduced forced vital capacity was less frequent (pooled prevalence 8%, 95% CI 6–11%); however, its prevalence was lower in the 12-month follow-up studies than in the 6-month follow-up studies (5% 95% CI 3–7% vs. 13% 95% CI 8–19%,
P
= 0.006). On follow-up chest CT, the pooled prevalence of persistent ground-glass opacities and pulmonary fibrosis was 34% (95% CI 24–44%) and 32% (95% CI 23–40%), respectively, and the prevalence did not decrease over time. As every meta-analysis showed significant between-study heterogeneity, subgroup and meta-regression analyses were performed to identify potential effect modifiers; the severity of index infection was associated with the prevalence of impaired diffusion capacity and pulmonary fibrosis.
Conclusions
A substantial number of COVID-19 survivors displayed pulmonary sequelae as part of PACS. Except for restrictive pulmonary dysfunction, the prevalence of these sequelae did not decrease until 1 year after initial infection. Considering the association between the severity of acute COVID-19 and risk of pulmonary sequelae, patients who recover from severe COVID-19 require close respiratory follow-up.
Systematic review registration number
PROSPERO CRD42021234357
The recent expansion of the Internet of Things (IoT) and the consequent explosion in the volume of data produced by smart devices have led to the outsourcing of data to designated data centers. ...However, to manage these huge data stores, centralized data centers, such as cloud storage cannot afford auspicious way. There are many challenges that must be addressed in the traditional network architecture due to the rapid growth in the diversity and number of devices connected to the internet, which is not designed to provide high availability, real-time data delivery, scalability, security, resilience, and low latency. To address these issues, this paper proposes a novel blockchain-based distributed cloud architecture with a software defined networking (SDN) enable controller fog nodes at the edge of the network to meet the required design principles. The proposed model is a distributed cloud architecture based on blockchain technology, which provides low-cost, secure, and on-demand access to the most competitive computing infrastructures in an IoT network. By creating a distributed cloud infrastructure, the proposed model enables cost-effective high-performance computing. Furthermore, to bring computing resources to the edge of the IoT network and allow low latency access to large amounts of data in a secure manner, we provide a secure distributed fog node architecture that uses SDN and blockchain techniques. Fog nodes are distributed fog computing entities that allow the deployment of fog services, and are formed by multiple computing resources at the edge of the IoT network. We evaluated the performance of our proposed architecture and compared it with the existing models using various performance measures. The results of our evaluation show that performance is improved by reducing the induced delay, reducing the response time, increasing throughput, and the ability to detect real-time attacks in the IoT network with low performance overheads.
Abstract Background Adipose-derived stem cells (ADSC) have wound-healing and antioxidant effects on human skin via secretion of growth factors and activation of dermal fibroblasts. Objective ...Paracrine mechanism reducing ultraviolet-B (UVB)-induced wrinkles by ADSC is investigated in this study. Methods and Results Wrinkles were induced by an eight-week UVB irradiation, and were significantly improved by the subcutaneous injection of ADSC in hairless mice. In a replica analysis, parameters involving wrinkles were improved with mid-level and high doses of ADSC (1 × 104 and 1 × 105 cells). Dermal thickness and collagen contents in the dermis also were increased in the ADSC-injected groups. To characterize the paracrine mechanism involving the antiwrinkle effect of ADSC, a conditioned medium of ADSC (ADSC-CM) was directly incubated in human dermal fibroblasts (HDF). UVB irradiation reduced the proliferation of HDF, but this was reversed by the pretreatment of ADSC-CM in a dose-dependent manner. In a cell cycle analysis, ADSC-CM decreased the UVB-induced apoptotic cell death, which was demonstrated by the reduced sub-G1 phase of HDF. In addition, the ADSC-CM increased the protein expression of collagen type I and decreased the protein level of matrix mataloproteinase 1 in HDF, which may account for the increased collagen contents in the dermis. Conclusions Collectively, these results indicate that the ADSC and its secretory factors are effective for UVB-induced wrinkles, and the antiwrinkle effect is mainly mediated by reducing UVB-induced apoptosis and stimulating collagen synthesis of HDF.
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