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Significance Despite sharing the first four reactions, coutilization of the Wood–Ljungdahl pathway (WLP) with the glycine synthase-reductase pathway (GSRP) and reductive glycine pathway (RGP) to fix C1 compounds has remained unknown. In this study, using Clostridium drakei, we elucidated the role of the GSRP and RGP in the presence of the WLP, via a genome-scale metabolic model, RNA-seq, 13C isotope-based metabolite-tracing experiments, biochemical assays, and heterologous expression. Overall, the data suggested the pathways are functional under autotrophic conditions. Along with the WLP, GSRP and RGP convert CO2 to glycine and then to acetyl-phosphate and serine, which then obtain ATP by producing acetate and operate with limited reducing power. This is a unique coutilization of the pathways under autotrophic conditions in acetogens., Among CO2-fixing metabolic pathways in nature, the linear Wood–Ljungdahl pathway (WLP) in phylogenetically diverse acetate-forming acetogens comprises the most energetically efficient pathway, requires the least number of reactions, and converts CO2 to formate and then into acetyl-CoA. Despite two genes encoding glycine synthase being well-conserved in WLP gene clusters, the functional role of glycine synthase under autotrophic growth conditions has remained uncertain. Here, using the reconstructed genome-scale metabolic model iSL771 based on the completed genome sequence, transcriptomics, 13C isotope-based metabolite-tracing experiments, biochemical assays, and heterologous expression of the pathway in another acetogen, we discovered that the WLP and the glycine synthase pathway are functionally interconnected to fix CO2, subsequently converting CO2 into acetyl-CoA, acetyl-phosphate, and serine. Moreover, the functional cooperation of the pathways enhances CO2 consumption and cellular growth rates via bypassing reducing power required reactions for cellular metabolism during autotrophic growth of acetogens.

As a multi-hop extension of the desynchronization-based TDMA (Desync-TDMA), the extended Desync-TDMA (Ext-Desync) with self-adapting property is proposed to overcome the limitations of existing CSMA/CA and dynamic TDMA-based schemes for Mobile Ad-hoc Networks (MANETs). However, existing studies overlooked the potential problem of firing message collisions caused by node movements, leading to the severe degradation of MANET networking performance. In this paper, we derive a mathematical model to evaluate the problem due to collisions of firing messages for moving nodes. With the derived model, we propose a method for a collided node to determine whether it changes its firing phase or not, adaptively in a distributed manner, by considering both the collision situation and the slot utilization. The comparative analysis between the proposed method and existing representative ones is also presented for various networking features. The performances of the proposed method are compared with CSMA/CA as well as other existing Ext-Desync-based schemes. The numerical results show that the proposed method achieved much faster resolution and higher slot utilization in collision situations than other Ext-Desync-based schemes. In addition, we also show that the proposed method outperformed the comparable methods, including CSMA/CA, in terms of packet delivery ratios and end-to-end delays.

Objective: The factors related to paradoxical excitement during propofol-induced sedation remain unclear. We aimed to investigate this issue during sedated upper endoscopy.Material and meth...

Currently, network applications, such as audio, video, and augmented reality, have different stringent service requirements. They require service provision through end-to-end connections via other networks with different operating environments or service conditions. Therefore, network operators require information on their own and other networks to provide end-to-end services traversing several networks while guaranteeing their quality of service (QoS) requirements. This study proposes an inter-domain flow decision method that satisfies QoS requirements using a directed acyclic graph (DAG) in multi-domain and hierarchical software defined networking (SDN) networks. There are multiple local networks with SDN controllers that are connected to the global SDN controller. The flow decision in the proposed method is based on the effective bandwidth theory of the martingale process. The effectiveness of the proposed method is demonstrated by comparing it with existing SDN-based path selection methods using the Riverbed Modeler (older, OPNET) and OpenDaylight SDN controllers.

Riverbed Modeler is a useful simulation tool that can simulate a variety of standard network models. However, it does not provide a related tool that does not suit the situation in which research on applying machine learning to the network domain is actively progressing. In this paper, we implemented a framework to apply reinforcement learning in a riverbed modeler environment. In order to efficiently perform reinforcement learning, we proposed a reinforcement learning structure that supports supervised learning to improve network performance using Riverbed Modeler and MATLAB. The proposed method was evaluated that the learning time was shortened compared to the existing reinforcement learning environment through experiments.

Deployment of new optimized routing rules on routers are challenging, owing to the tight coupling of the data and control planes and a lack of global topological information. Due to the distributed nature of the traditional classical internet protocol networks, the routing rules and policies are disseminated in a decentralized manner, which causes looping issues during link failure. Software-defined networking (SDN) provides programmability to the network from a central point. Consequently, the nodes or data plane devices in SDN only forward packets and the complexity of the control plane is handed over to the controller. Therefore, the controller installs the rules and policies from a central location. Due to the central control, link failure identification and restoration becomes pliable because the controller has information about the global network topology. Similarly, new optimized rules for link recovery can be deployed from the central point. Herein, we review several schemes for link failure recovery by leveraging SDN while delineating the cons of traditional networking. We also investigate the open research questions posed due to the SDN architecture. This paper also analyzes the proactive and reactive schemes in SDN using the OpenDayLight controller and Mininet, with the simulation of application scenarios from the tactical and data center networks.

The increased usage of wireless communication has created a wireless frequency shortage problem. Cognitive Radio (CR) has attracted public attention, as one of the solutions that can resolve this issue. In this paper, the authors built an actual CR system testbed using the SDR (Software Defined Radio) platform, USRP (Universal Software Radio Peripheral) board, the SDR development toolkit, GNU Radio, and Raspberry Pi3, which is a single board computer. They configured Secondary User (SU)s with Raspberry Pi3 for straightforward and portable test environment. The authors' testbed performs spectrum sensing based on energy detection and determines whether the channel is occupied or not. Experimental results not only show performance but also provide their testbed that works well in multi-hop environments.

Cognitive radio (CR) is a spectrum sharing technology that facilitates a hierarchal coexistence between licensed and license-exempt users over licensed bands. One of the biggest challenges in cognitive radio network (CRN) is efficient spectrum management. Recently, a trend has shifted towards the use of machine learning techniques such as reinforcement learning for learning problem in CRN. This paper provides an insight into the working principles of reinforcement learning based CRN and summarizes the recent survey papers done on the topic of learning based CRN. This paper also presents a 5G technology i.e. network slicing, based intelligent CRN architecture for efficient spectrum management. Some challenges in the existing solutions and future research directions are also introduced.

To provide a more intuitive user experience, there have been studies to apply mixed reality to the Internet of Things. They have used a Mixed Reality device as a tailored user application only or proposed an early stage of the architecture without any considering the IoT service platform standard. In this paper, we introduce the architecture to integrate Mixed Reality Device to OneM2M, which is the most widely known IoT platform standard. For integration, we consider the three use cases of a Mixed Reality device in IoT service. Also, the demonstration showed the feasibility of the proposed idea with integrating Mobius platform, one of open source oneM2M IoT platform, and Hololens, MR device by Microsoft.

Desync TDMA is expected to overcome the limitations of CSMA/CA and existing D-TDMA in MANET because it has self-adapting property. Extended-Desync TDMA which is the multi-hop extension of the Desync TDMA can solve the hidden node problem. However, when a node recognizes collision of firing packet, it changes firing phase with a certain probability and can't transmit data at this time. In this paper, we propose a scheme to adjust the firing phase changing probability dynamically according to the collision situation of the firing packet in Extended-Desync TDMA. The proposed scheme improves performance by preventing frequent changes of firing phase in Extended-Desync TDMA.

With the advent of ubiquitous environments, the smart phone has come into wide use and the demand for various content increases. Thus, in order to efficiently utilize limited resources cognitive radio technology is regarded as a possible solution. Besides spectrum sensing or access schemes, the provision of VoIP traffic service for secondary users with limited spectrum resources is a very important issue. In this paper, a resource allocation and control system for VoIP QoS provision in cognitive radio networks is proposed. Firstly, as the system model, the time structure of the network is addressed and, according to the structure, a bandwidth broker is proposed. In addition, based on available bandwidth estimated by the bandwidth broker, a connection admission control for secondary users is developed. It is demonstrated that the provision of VoIP QoS is greatly affected by channel utilization, the number of channels, and the length of timeslot.

Amorphous metal oxide thin film transistors (TFTs) are expected to serve as building blocks in a variety of devices, such as bendable displays, transparent mobile phones, and plastic newspapers. Here, we report a simple approach for highly stable solution-based zinc oxide (ZnO) TFTs by simply evaporating Al on the back channel layer without any additional chemical or plasma process for passivation. In particular, control and manipulation of Al nanoparticle (NP) formation represents one of the key approaches in this work. The possible sketch of the improved nature is proposed, along with various structural and electrical analyses.

There is a growing need for a voice service with an advanced communication technology. In low infrastructure areas such as mountain, battlefield, and in-flight, a geostationary (GEO) satellite system is regarded as an alternative solution to provide real-time voice services. In this paper, an effective bandwidth based capacity request for real-time voice traffic in military satellite system. First, the transparent satellite architecture for continuous rate assignment (CRA) request procedure is proposed. Next, for an accurate estimation of effective bandwidth, we implement a voice traffic model multiplexed in the return channel satellite terminals (RCST), which is originated from user terminals (UTs) and multiplexed in an RCST. Further, an analytical model is developed for evaluating the performance, such as the capacity requests, the number of available RCSTs, optimal medium access control (MAC) queue length, and ratio of resource waste. It is demonstrated that the proposed scheme has high efficiency of resource allocation, and low ratio of resource waste.