• Title/Summary/Keyword: Defense mechanism

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"Maintenance"-mode feedback and the host galaxies of radio-AGN

  • Karouzos, Marios;Im, Myungshin;Trichas, Markos
    • The Bulletin of The Korean Astronomical Society
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    • v.39 no.1
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    • pp.37.1-37.1
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    • 2014
  • There exists strong evidence supporting the co-evolution of central supermassive black holes and their host galaxies; however it is still under debate how such a relation comes about and whether it is relevant for all or only a subset of galaxies. An important mechanism connecting AGN to their host galaxies is AGN feedback, potentially heating up or even expelling gas from galaxies. AGN feedback may hence be responsible for the eventual quenching of star formation and halting of galaxy growth. A rich multi-wavelength dataset ranging from the X-ray regime (Chandra), to far-IR (Herschel), and radio (WSRT) is available for the North Ecliptic Pole field, most notably surveyed by the AKARI infrared space telescope, covering a total area on the sky of 5.4 sq. degrees. We investigate the star-formation properties and possible signatures of radio feedback mechanisms in the host galaxies of 237 radio-AGN below redshift z=2 and at a radio 1.4 GHz flux density limit of 0.1 mJy. Using broadband SED modeling, the nuclear and host galaxy components of these sources are studied simultaneously as a function of their radio luminosity. Here we present results concerning the AGN content of the radio sources in this field, while offering evidence supporting a "maintenance" type of feedback from powerful radio-jets.

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Development of Secretory Element in Murine Trachea and Larynx (백서 기관 및 후두에서 분비조직의 발생)

  • 조정일;박기현;김광문
    • Proceedings of the KOR-BRONCHOESO Conference
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    • 1993.05a
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    • pp.67-67
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    • 1993
  • Mucosal surface of the trachea and larynx is protected by several complex defense mechanism, namely mucociliary clearance, immunoglobulin, antibacterial secretory enzyme, which have also been demonstrated in the middle ear mucosa and eustachian tube. The morphologgy of secretory glands and cells of the trachea and larynx is well-known, but knowledge concerning their development related to secretory activity is still sketchy. The secretory element of the murine trachea and larynx, aging from gestational day 16 to postnatal day 21, was studied using hematoxylin & eosin and alcian blue/periodic acid-Schiff staining including lysozyme immunohistochemistry to investigate the development of secretory element of the murine trachea and larynx and to provide with basis of the future study for developmental morphology of the trachea and larynx. The results of this study suggest that the secretory activity starts to be established immediately after birth with the aeration of the lung.

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Isolation and Characterization of Calmodulin 2 (CICAM2) Gene from Codonopsis lanceolata

  • Lee, Kang;In, Jun-Gyo;Yu, Chang-Yeon;Min, Byung-Hoon;Chung, Ill-Min;Kim, Se-Young;Kim, Yeong-Chae;Yang, Deok-Chun
    • Plant Resources
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    • v.7 no.3
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    • pp.174-180
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    • 2004
  • Calmodulin, a $Ca^{2+}$-binding protein, has no enzyme activity. It combines with $Ca^{2+}$ and makes variable proteins to an active form. Calmodulin 2 is a ubiquitous protein in plants. To investigate the defense mechanism against various stresses, a clone encoding a calmodulin 2 protein was isolated from a cDNA library prepared from taproot mRNAs of Codonopsis lanceolata. The cDNA, designated CICAM2, is 719 nucleotides long and has an open reading frame of 450 bp with a deduced amino acid sequence of 149 residues. The deduced amino acid sequence of CICAM2 showed a high similarity with calmodulins of P. x hybrida (P27163) 97%, N. tabacum (BAB61908) 97%, S. tuberosum (AAA74405) 96%, Z. mays (CAA74307) 92%, C. richardii (AF510075) 93%, M. truncatula (AAM81203) 91%, and G. max (P62163) 91%. The transcriptional expression of the CICAM2 gene, was gradually increased by the CaCl$_2$ treatment. Whereas its expression And it was gradually decreased in the cold stress treatment.ent.

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Isolation and Transcriptional Expression of CuZn Superoxide Dismutase from Codonopsis lanceolata

  • Lee, Kang;In, Jun-Gyo;Yu, Chang-Yeon;Yun, Song-Joong;Min, Byung-Hoon;Rho, Yeong-Deok;Kim, Moo-Sung;Yang, Deok-Chun
    • Plant Resources
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    • v.7 no.3
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    • pp.163-169
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    • 2004
  • To investigate the defense mechanism against the abiotic stress, a cDNA clone encoding a CuZn superoxide dismutase (CuZnSOD) protein was isolated from a cDNA library prepared from tabroot mRNAs of Codonopsis lanceolata. The eDNA, designated ClSODCc, is 799 nucleotides long and has an open reading frame of 459 bp with a deduced amino acid sequence of 152 residues. The deduced amino acid sequence of ClSODCc matched to the previously reported CuZnSODs. Consensus amino acid residues (His-45, -47, -62, -70, -79, -119 and Asp-82) were involved in Cu-, Cu/Zn-, and Zn- binding ligands. The deduced amino acid sequence of ClSODCc showed high homologies (82%-86%) regardless of species. Expression of ClSODCc by oxidative stress was increased up to 1 h after treatment and declined gradually. Much earlier and stronger expression of ClSODCc was observed in the cold stress treatment.

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Enhanced OLSR for Defense against DOS Attack in Ad Hoc Networks

  • Marimuthu, Mohanapriya;Krishnamurthi, Ilango
    • Journal of Communications and Networks
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    • v.15 no.1
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    • pp.31-37
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    • 2013
  • Mobile ad hoc networks (MANET) refers to a network designed for special applications for which it is difficult to use a backbone network. In MANETs, applications are mostly involved with sensitive and secret information. Since MANET assumes a trusted environment for routing, security is a major issue. In this paper we analyze the vulnerabilities of a pro-active routing protocol called optimized link state routing (OLSR) against a specific type of denial-of-service (DOS) attack called node isolation attack. Analyzing the attack, we propose a mechanism called enhanced OLSR (EOLSR) protocol which is a trust based technique to secure the OLSR nodes against the attack. Our technique is capable of finding whether a node is advertising correct topology information or not by verifying its Hello packets, thus detecting node isolation attacks. The experiment results show that our protocol is able to achieve routing security with 45% increase in packet delivery ratio and 44% reduction in packet loss rate when compared to standard OLSR under node isolation attack. Our technique is light weight because it doesn't involve high computational complexity for securing the network.

Unethical Network Attack Detection and Prevention using Fuzzy based Decision System in Mobile Ad-hoc Networks

  • Thanuja, R.;Umamakeswari, A.
    • Journal of Electrical Engineering and Technology
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    • v.13 no.5
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    • pp.2086-2098
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    • 2018
  • Security plays a vital role and is the key challenge in Mobile Ad-hoc Networks (MANET). Infrastructure-less nature of MANET makes it arduous to envisage the genre of topology. Due to its inexhaustible access, information disseminated by roaming nodes to other nodes is susceptible to many hazardous attacks. Intrusion Detection and Prevention System (IDPS) is undoubtedly a defense structure to address threats in MANET. Many IDPS methods have been developed to ascertain the exceptional behavior in these networks. Key issue in such IDPS is lack of fast self-organized learning engine that facilitates comprehensive situation awareness for optimum decision making. Proposed "Intelligent Behavioral Hybridized Intrusion Detection and Prevention System (IBH_IDPS)" is built with computational intelligence to detect complex multistage attacks making the system robust and reliable. The System comprises of an Intelligent Client Agent and a Smart Server empowered with fuzzy inference rule-based service engine to ensure confidentiality and integrity of network. Distributed Intelligent Client Agents incorporated with centralized Smart Server makes it capable of analyzing and categorizing unethical incidents appropriately through unsupervised learning mechanism. Experimental analysis proves the proposed model is highly attack resistant, reliable and secure on devices and shows promising gains with assured delivery ratio, low end-to-end delay compared to existing approach.

FIR Filter for Defense Mechanism against Malicious Cyber Attacks (악의적 사이버 공격을 무력화하기 위한 FIR 필터에 관한 연구)

  • Lee, Sang-Su;Kim, Kwan-Soo;Kang, Hyun-Ho;You, Sung-Hyun;Lee, Dhong-Hun;Lee, Dong-Kyu;Kim, Young-Eun;Ahn, Choon-Ki
    • Proceedings of the Korea Information Processing Society Conference
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    • 2018.10a
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    • pp.438-441
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    • 2018
  • In this paper, we propose a finite impulse response (FIR) filter under malicious cyber attacks. The FIR filter shows the robust performance against the malicious cyber attacks. The Kalman filter (KF), one of the widely used filters, is introduced as a comparison of robust performance of the proposed method. The robust performance of the proposed method under malicious cyber attacks is demonstrated through experimental results.

The Phenotype of the Soybean Disease-Lesion Mimic (dlm) Mutant is Light-Dependent and Associated with Chloroplast Function

  • Kim, Byo-Kyong;Kim, Young-Jin;Paek, Kyoung-Bee;Chung, Jong-Il;Kim, Jeong-Kook
    • The Plant Pathology Journal
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    • v.21 no.4
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    • pp.395-401
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    • 2005
  • The dlm (disease lesion mimic) mutant of soybean (Glycine max L. Merr) shows the similar lesion of a soybean disease caused by a fungus, Corynespora cassilcola. The lesion was examined at cellular and molecular level. Trypan blue staining result indicated that cell death was detectable in the entire region of leaves excluding veins when the lesions had already been developed. We found that the mesophyll cells of palisade layer in the dim mutant appeared to be wider apart from each other. The chloroplasts of the dim mutant cells contained bigger starch granules than those in normal plants. We also found that the lesion development of dlm plant was light-dependent and the starch degradation during the dark period of diurnal cycle was impaired in the mutant. Three soybean pathogenesis-related genes, PR-1a, PR-4, and PR-10, were examined for their expression patterns during the development of disease lesion mimic. The expression of all three genes was up-regulated to some extent upon the appearance of the disease lesion mimic. Although the exact function of DLM protein remains elusive, our data would provide some insight into mechanism underling the cell death associated with the dim mutation.

The Activity of Apo-transferrin on the Growth of Staphylococcus pseudintermedius

  • Bae, Seul-gi;Kim, Youn-Ju;Oh, Tae-Ho
    • Journal of Veterinary Clinics
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    • v.34 no.2
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    • pp.87-89
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    • 2017
  • Apo-transferrin is an iron-binding protein that has been reported to have an antimicrobial effect. It is considered a major component of the host defense mechanism as it limits microbial access to iron. This study was performed to investigate whether bovine apo-transferrin would have an inhibitory effect on the growth of S. pseudintermedius, which is one of the most isolated bacteria from dogs, and to compare the antimicrobial efficacy with bovine holo-transferrin. S. pseudintermedius were grown at $37^{\circ}C$ in 96-well culture plates using Muller Hinton broth containing bovine apo-transferrin or bovine holo-transferrin at concentrations ranging from 0.5 or 2.5 to 5.0 mg/ml. The optical densities of the wells were then measured at 570 nm. In this study, the apo-transferrin showed dose-dependent antimicrobial effect against S. pseudintermedius while holo-transferrin did not inhibit the growth of S. pseudintermedius effectively. The results suggest that iron deprivation is an important pathway for inhibiting bacterial growth and bovine apo-transferrin has great antimicrobial effects against S. pseudintermedius.

Functional Implications in Apoptosis by Interferon Inducible Gene Product 1-8D, the Binding Protein to Adenovirus Preterminal Protein

  • Joung, In-Sil;Angeletti, Peter C.;Engler, Jeffrey A.
    • Journal of Microbiology
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    • v.41 no.4
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    • pp.295-299
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    • 2003
  • Adenovirus (Ad) precursor to the terminal protein (pTP) plays an essential roles in the viral DNA replication. Ad pTP serves as a primer for the synthesis of a new DNA strand during the initiation step of replication. In addition, Ad pTP forms organized spherical replication foci on the nuclear matrix (NM) and anchors the viral genome to the NM. Here we identified the interferon inducible gene product 1-8D (Inid) as a pTP binding protein by using a two-hybrid screen of a HeLa cDNA library. Of the clones obtained in this assay, nine were identical to the Inid, a 13-kDa polypeptide that shares homology with genes 1-8U and Leu-13/9-27, most of which have little known functions. The entire open reading frame (ORF) of Inid was cloned into the tetracycline inducible expression vector in order to determine the biological functions related with adenoviral infection. When Inid was introduced to the cells along with adenoviruses, fifty to sixty percent of Ad-infected cells expressing Inid had rounded morphology, which was suggestive of apoptosis. Results from the terminal deoxynucleotidyl transferase (TdT) and DNA fragmentation assays confirmed that Inid induces apoptosis in Ad-infected or in uninfected cells. The Inid binding to pTP may target the cell for apoptotic destruction as a host defense mechanism against the viral infection.