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Mobile robot localizations have been extensively studied, and various algorithms for multiple-robot localization have been developed. However, existing methods for multiple-robot localization often exhibit poor performance under harsh conditions, such as missing measurements and sudden appearance of obstacles. To overcome this problem, this paper proposes a novel method for multiple-robot localization in wireless sensor networks. The proposed method is theoretically based on the finite memory estimation and utilizes relative distance and angle measurements between robots. Thus, the proposed method is referred to as distributed finite memory estimation from relative measurements (DFMERM). Due to the finite memory structure, the DFMERM has inherent robustness against computational and modeling errors. Moreover, the novel distributed localization method using relative measurements shows the robustness against missing measurements. Robust DFMERM localization performance is experimentally demonstrated using multiple mobile robots under the harsh conditions.

In this letter, a synchronization signal design technique for millimeter-wave cellular vehicle-to-everything (C-V2X) communications is proposed. The proposed vehicle synchronization signal generated using a generalized reciprocal sequence of m-sequence is shown to have desirable properties for orthogonal frequency division multiplexing (OFDM)-based C-V2X, particularly for vehicle-to-vehicle (V2V) synchronization. It is shown that the detection probabilities of synchronization signals in C-V2X are not degraded when base stations and vehicles coexist, owing to minimal interference between the synchronization signals. Moreover, the computational complexity required for signal detection and synchronization in V2V links can be significantly reduced with the proposed vehicle synchronization signal.

This paper proposes a downlink synchronization and cell identity (CID) estimation technique for cellular systems based on orthogonal time-frequency space (OTFS). In the proposed technique, each base station (BS) transmits one detection preamble (DP) and two OTFS symbols (pilot and secondary-CID (SCID) signal (SS)). The DP based on a linear frequency-modulated (LFM) waveform, called proposed-LFM (pLFM), carries the primary-CID (PCID) for symbol timing (ST) synchronization, whereas the SS based on the Zadoff-Chu (ZC) sequence mapped in the delay-Doppler domain carries the SCID. The pLFM is obtained by discretizing the LFM waveform, increasing the frequency sweeping parameter beyond the limit of the operational bandwidth, and incorporating the PCID into the LFM waveform. The autocorrelation and cross-correlation functions of the pLFM are analyzed to examine its correlation properties under the influence of a high Doppler shift. To reduce the undesirable correlation properties (side peak and time ambiguity), a receiver processing (RP) scheme is developed for the pLFM. It is found that the pLFM with RP is suitable for the DP design because it can provide an accurate ST in high-mobility scenarios. In addition, the influence of OTFS modulation on the ZC sequence is derived and a low-complexity detection algorithm based on message passing is applied to detect SCID at the user equipment. The simulation results demonstrate that the proposed downlink synchronization and CID estimation techniques are suitable for OTFS-based cellular systems in high-Doppler environments.

Beam training in millimeter-wave (mmWave) cellular systems requires a long processing time that is proportional to the product of the number of transmitting and receiving beams. In this paper, we propose a beam training technique that can significantly reduce the beam training time in mmWave cellular systems, using a retrodirective directional array (RDA). In the proposed technique, the beam sweeping operations required at the base station (BS) and mobile station (MS) are significantly reduced owing to the use of the RDA, which automatically returns a signal in the direction along which it originated. A preamble sequence design technique for beam training is proposed to identify the BS, MS, and beams simultaneously transmitted from the BS/MS, using the Zadoff-Chu sequence. The ambiguity condition and detection algorithms are derived so that we can uniquely identify the parameters for beam alignment in asynchronous environments with symbol timing offset (STO) and carrier frequency offset (CFO). Simulations show that the proposed algorithm can correctly detect the parameters for beam alignment in mmWave cellular systems with RDA in asynchronous environments. Moreover, the proposed technique can significantly reduce the period required for beam training, compared with the conventional techniques.

Due to short wavelength and weak diffraction ability, millimeter-wave (mmWave) signals are highly susceptible to blockage, which results in significant degradation in received signal power. As a possible solution for overcoming the blockage problem in millimeter-wave communication systems, the deployment of a relay station (RS) has been considered in recent years. In this paper, we discuss the problems to be considered in a relay-assisted mmWave cellular system based on orthogonal frequency division multiplexing. We describe a frame structure and a pilot-based training method to achieve efficient RS selection during blockage. In addition, a method designed to overcome the inter-symbol interference problem caused by different symbol time offsets of pilot signals received from adjacent RSs in the relay-assisted mmWave cellular system is discussed. Then, we propose two different types of pilot sequences that allow a mobile station to distinguish among the pilot sources in multi-cell multi-relay environments: pilot signals based on the Zadoff-Chu sequence (PS1) and pilot signals based on the m-sequence (PS2). The correlation property of PS2 is derived and compared with that of PS1 and another sequence (Gold sequence). Simulations are performed using a blockage model to verify the properties, constraints, and advantages and disadvantages of the proposed pilot sequences in RS-assisted mmWave cellular systems.

The ubiquitin proteasome system (UPS) is a protein degradation machinery that is crucial for cellular homeostasis in eukaryotes. Therefore, it is not surprising that the UPS coordinates almost all host cellular processes, including host–pathogen interactions. This protein degradation machinery acts predominantly by tagging substrate proteins designated for degradation with a ubiquitin molecule. These ubiquitin tags have been involved at various steps of the innate immune response. Hence, herpesviruses have evolved ways to antagonize the host defense mechanisms by targeting UPS components such as ubiquitin E3 ligases and deubiquitinases (DUBs) that establish a productive infection. This review delineates how herpesviruses usurp the critical roles of ubiquitin E3 ligases and DUBs in innate immune response to escape host-antiviral immune response, with particular focus on retinoic acid-inducible gene I (RIG-I)-like receptors (RLR), cyclic-GMP-AMP (cGAMP) synthase (cGAS), stimulator of interferon (IFN) genes (STING) pathways, and inflammasome signaling.

Mycobacterium abscessus(MAB) is one of the rapidly growing, multidrug-resistant non-tuberculous mycobacteria (NTM) causing various diseases including pulmonary disorder. Although it has been known that type I interferons (IFNs) contribute to host defense against bacterial infections, the role of type I IFNs against MAB infection is still unclear. In the present study, we show that rIFN-β treatment reduced the intracellular growth of MAB in macrophages. Deficiency of IFN-α/β receptor (IFNAR) led to the reduction of nitric oxide (NO) production in MAB-infected macrophages. Consistently, rIFN-β treatment enhanced the expression of iNOS gene and protein, and NO production in response to MAB. We also found that NO is essential for the intracellular growth control of MAB within macrophages in an inhibitor assay using iNOS-deficient cells. In addition, pretreatment of rIFN-β before MAB infection in mice increased production of NO in the lungs at day 1 after infection and promoted the bacterial clearance at day 5. However, when alveolar macrophages were depleted by treatment of clodronate liposome, rIFN-β did not promote the bacterial clearance in the lungs. Moreover, we found that a cytosolic receptor nucleotide-binding oligomerization domain 2 (NOD2) is required for MAB-induced TANK binding kinase 1 (TBK1) phosphorylation and IFN-β gene expression in macrophages. Finally, increase in the bacterial loads caused by reduction of NO levels was reversed by rIFN-β treatment in the lungs of NOD2-deficient mice. Collectively, our findings suggest that type I IFNs act as an intermediator of NOD2-induced NO production in macrophages and thus contribute to host defense against MAB infection.

In underwater acoustic cellular (UWAC) systems, underwater equipment or sensor nodes (UE/SN) should perform downlink synchronisation and a cell search during the initial access stage using the preambles received from adjacent underwater base stations (UWBSs). The UE/SN needs to estimate accurate timing and cell ID (CID) using the received preambles, and synchronise with a serving UWBS, even in high-Doppler environments. In this paper, a sequence design technique for joint estimation of accurate timing and CID in UWAC systems with a high Doppler is proposed to decrease the receiver complexity and processing time. A generalised Zadoff–Chu sequence is proposed for the preamble design. This sequence is decomposed into multiple short sub-sequences to reduce the effect of Doppler shift on the timing and CID estimation. The performance loss caused by the short sequence length is compensated by combining the sub-sequences using the repetition property of the ZC sequence. The properties (autocorrelation and cross-correlation) of the proposed sequence are derived analytically in the presence of Doppler shift and compared with the simulation results. The simulation results reveal that the proposed technique performs better than existing techniques in both additive white Gaussian noise and multipath channels with a high-Doppler. It is concluded that the proposed technique is suitable for accurate timing estimation and CID detection in UWAC systems with a high Doppler.

Spatial and temporal exploration of charge carriers with secondary electrons emitted from surfaces and interfaces of materials offers novel and complementary opportunities for deepening our knowledge about charge transport in real space and time for technologically relevant device applications, ranging from electronics to optoelectronics and plasmonics. The time-resolved signal contrast obtained from these explorations depends on the detailed mechanisms of internal electrons escaping from materials systems, yielding either bright or dark image contrast. However, a deeper microscopic understanding of an element-specific structure-property relationship leading to different dynamic signal contrast remains largely elusive. Here, we present the results of coupled-rate-equation-based model simulations, and discuss the energetics of the internal electrons and energy-loss mechanisms along with effective probe length scales, to account for the dark contrast of emitted secondary electrons observed in semiconducting materials systems.

A new variant of SARS-CoV-2 B.1.351 lineage (first found in South Africa) has been raising global concern due to its harboring of multiple mutations in the spike that potentially increase transmissibility and yield resistance to neutralizing antibodies. We here tested infectivity and neutralization efficiency of SARS-CoV-2 spike pseudoviruses bearing particular mutations of the receptor-binding domain (RBD) derived either from the Wuhan strains (referred to as D614G or with other sites) or the B.1.351 lineage (referred to as N501Y, K417N, and E484K). The three different pseudoviruses B.1.351 lineage related significantly increased infectivity compared with other mutants that indicated Wuhan strains. Interestingly, K417N and E484K mutations dramatically enhanced cell–cell fusion than N501Y even though their infectivity were similar, suggesting that K417N and E484K mutations harboring SARS-CoV-2 variant might be more transmissible than N501Y mutation containing SARS-CoV-2 variant. We also investigated the efficacy of two different monoclonal antibodies, Casirivimab and Imdevimab that neutralized SARS-CoV-2, against several kinds of pseudoviruses which indicated Wuhan or B.1.351 lineage. Remarkably, Imdevimab effectively neutralized B.1.351 lineage pseudoviruses containing N501Y, K417N, and E484K mutations, while Casirivimab partially affected them. Overall, our results underscore the importance of B.1.351 lineage SARS-CoV-2 in the viral spread and its implication for antibody efficacy.

ICT industry is the fastest growing and most volatile industry, and firms must continue to innovate and improve technology. At the same time, they also need to increase shareholders' wealth by efficiently creating firm value with given resources. Thus, in corporate finance, many studies have assessed the impact of capital structures and their determinants on the value or performance of a firm. But the results have yet to be agreed upon by the country and industry. Existing studies have also used Tobin's Q as a measure of firm value, but Tobin Q has limitations that it cannot effectively reflect firm value, a multi-dimensional and complex concept. Therefore, this study measures the value of Korean ICT manufacturing and service businesses using DEA, and uses Tobit regression to evaluate the impact of capital structure on its profitability efficiency. The analysis results showed that 1. The profitability efficiency of SMEs was the best in both industries, 2. The liquidity ratio had a positive effect on the profitability efficiency of small and medium-sized manufacturing enterprises, and 3. The debt ratio had a positive impact on the efficiency of medium-sized firms in the service industry. Accordingly, this research suggests implications for enhancing the value creation of Korean ICT firms. This study is expected to contribute not only to the study of insufficient capital structure for Korean ICT firms, but also to enrich the study of capital structures whose impact on firm value is not agreed upon.

Previously, we found that the water extract of Artermisia scoparia Waldst.Kit suppressed the cytokine production of lipopolysaccharide (LPS)-stimulated macrophages and alleviated carrageenan-induced acute inflammation in mice. Artemisia contains various sesquiterpene lactones and most of them exert immunomodulatory activity.In the present study, we investigated the immunomodulatory effect of estafiatin (EST), a sesquiterpene lactone derived from A. scoparia, on LPS-induced inflammation in macrophages and mouse sepsis model.Murine bone marrow-derived macrophages (BMDMs) and THP-1 cells, a human monocytic leukemia cell line, were pretreated with different doses of EST for 2 h, followed by LPS treatment. The gene and protein expression of pro-inflammatory cytokines interleukin (IL)-6, tumor necrosis factor (TNF)-α, and inducible nitric oxide synthase (iNOS) were measured by quantitative real-time polymerase chain reaction (qPCR) and Western blot analysis. The activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) was also evaluated at the level of phosphorylation. The effect of EST on inflammatory cytokine production, lung histopathology, and survival rate was assessed in an LPS-induced mice model of septic shock. The effect of EST on the production of cytokines in LPS-stimulated peritoneal macrophages was evaluated by in vitro and ex vivo experiments and protective effect of EST on cecal ligation and puncture (CLP) mice was also assessed.The LPS-induced expression of IL-6, TNF-α, and iNOS was suppressed at the mRNA and protein levels in BMDMs and THP-1 cells, respectively, by pretreatment with EST. The half-maximal inhibitory concentration (ICThese results demonstrated that EST exerts anti-inflammatory effects on LPS-stimulated macrophages and protects mice from sepsis. Our study suggests that EST could be developed as a new therapeutic agent for sepsis and various inflammatory diseases.

The deployment of relay stations (RS) has been regarded as a possible solution to the blocking problem in millimeter wave (mmWave) communication systems. In this paper, we discuss issues to be considered in relay-assisted mmWave cellular systems based on orthogonal frequency division multiplexing. We describe a pilot-based training method to achieve effective RS selection during blockage. We propose two different types of pilot sequences, which allow mobile stations to distinguish pilot sources in a multi-cell multi-relay environment: pilot signals based on Zadoff-Chu sequence (PS1) and m-sequence (PS2). Correlation properties of PS1 and PS2 are derived and compared with that of the conventional sequence (Gold sequence). A blocking model is used to verify the properties, constraints, advantages, and disadvantages of the proposed pilot sequences in the RS-assisted mmWave cellular system.

A vehicle synchronization signal design technique for millimeter-wave cellular vehicle-to-everything (C-V2X) communications is proposed. The proposed vehicle synchronization signal generated using a generalized reciprocal sequence of m-sequence is shown to have desirable properties for orthogonal frequency division multiplexing (OFDM)-based C-V2X, particularly for vehicle-to-vehicle (V2V) synchronization. It is shown that the detection probabilities of synchronization signals in C-V2X are not degraded when base stations and vehicles coexist, and the computational complexity can be significantly reduced with the proposed vehicle synchronization signal.

Ethnopharmacological relevance Artemisia scoparia Waldst. & Kitam (A. scoparia) is a perennial herbal plant that is widely used as a folk remedy in Asian countries. Several studies have demonstrated that A. scoparia has various physiological effects, including anti-inflammation, anti-hypertension, anti-obesity, anti-hepatotoxicity, and anti-oxidant effects. Aim of the study: The objective of the present study was to examine the anti-inflammatory effects of water extract of A. scoparia (WAS). Materials and methods Murine bone marrow-derived macrophages (BMDMs), human monocyte THP-1 and murine fibroblast 3T3-L1 cells were used for the in vitro experiments. Cell viability and cytokine production were determined by the MTT assay and ELISA, respectively. RT-PCR was performed to determine iNOS gene expression and the Griess reaction was used to measure nitrite levels. iNOS protein expression, activation of NF-κB and MAPKs, and cleavage of caspase-1 and IL-1β were determined by Western blot analysis. A carrageenan-induced mouse model of acute inflammation was used in the in vivo experiments. Results Pretreatment with WAS concentration-dependently suppressed gene expression and IL-6, TNF-α, CXCL1 and iNOS protein levels in BMDMs stimulated with LPS. In addition, pretreatment with WAS inhibited LPS-induced production of IL-6 and TNF-α in THP-1 cells and CXCL1 in 3T3-L1. Furthermore, LPS induced phosphorylation of p65 in BMDMs, and this induction was dramatically suppressed by WAS pretreatment. We further investigated whether WAS regulates activation of the NLRP3 inflammasome, which is known to be essential for IL-1β processing. WAS inhibited the production of IL-1β, but not IL-6, in response to adenosine triphosphate (ATP) and monosodium uric acid (MSU) crystals in LPS-primed BMDMs. Cleavage of caspase-1 and IL-1β was also reduced by WAS. We finally evaluated the in vivo anti-inflammatory effects of WAS in a mouse model of carrageenan-induced acute inflammation. Subcutaneous administration of WAS reduced production of the inflammatory cytokines IL-6, TNF-α, CXCL1, and IL-1β. Recruitment of immune cells, mostly neutrophils, was also reduced by administration of WAS. Infiltration of inflammatory cells and edema in the submucosa of air pouch tissues were markedly improved in the WAS-treated groups. Conclusions Our results indicate that WAS possesses potent anti-inflammatory properties. These findings suggest that A. scoparia is a candidate functional food targeting several inflammatory diseases.

Millimeter-wave (mmWave) bands is considered for fifth-generation (5G) cellular systems because abundant spectrum is available for mobile broadband communications. In mmWave communication systems, accurate beamforming is important to compensate for high attenuation in the mmWave frequency band and to extend the transmission range. However, with the existing beamformers in mmWave cellular systems, the mobile station (MS) cannot identify the source (base station, BS) of the received beam because there are many neighboring BSs transmitting their training signals, requiring a large overhead. This paper proposes a new beam weight generation method for transmitting (Tx) beamformers at the BS in mmWave cellular systems during a beam training period. Beam weights are generated for Tx beamformers at neighboring BSs, so that a mobile station (MS) can estimate the source (cell ID, CID) and angle of departure (AoD) for each BS in multi-cell environments. A CID and AoD estimation method for mmWave cellular systems in a line-of-sight (LOS) dominant condition is presented using the beam weights generated by Zadoff-Chu sequence. A simulation is conducted in a LOS dominant condition to show that the performances of CID detection and AoD estimation are similar for both the proposed and conventional methods. In the conventional methods, the DFT-based beamforming weight is used for Tx beamformer at the BS and orthogonal matching pursuit (OMP) algorithm is used for AoD estimation at the MS. The proposed method significantly reduces the processing time (1.6&ndash, 6.25%) required for beam training compared to the conventional method.