• Title/Summary/Keyword: Direct detection

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Rapid and Direct Detection of Vibrio vulnificus in Small Octopus (Octopus variabilis) Using Polymerase Chain Reaction

  • Choi, Sang-Ho;Lee, Jee-Yeon
    • Journal of Microbiology and Biotechnology
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    • v.5 no.4
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    • pp.181-187
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    • 1995
  • The cells of Vibrio vulnificus can be induced to the viable but nonculturable (VBNC) state by natural environmental parameters. The V. vulnificus cells in the VBNC state can not be recovered by ordinary laboratory techniques. This nonculturability could often hamper development of effective processing strategies to minimize the number of V. vulnificus in seafoods. Even with V. vulnificus cells in a culturable state, the length of time required to identify the bacteria in contaminated food by phenotyphic characterization may prevent appropriate in-time responses by public health agencies to infections of the bacteria. In the present study, we used polymerase chain reaction (PCR) to develop a rapid and direct detection method for V. vulnificus in small octopus (Octopus variabilis) which is consumed as a raw food in Korea. The region targeted was a 704-base pair (bp) portion of the hemolysin gene, vvhA, of V. vulnificus. The primers designed for PCR amplification were specific for all V. vulnificus sp. tested. Several methods were examined to extract total DNA directly from V. vulnificus seeded into the octopus homogenate and the guanidine isothiocyanate (CITC) method appeared to be most effective. From the octopus homogenate seeded by V. vulnificus at an initial level of $10^2$ CFU/ml of the homogenate and then incubated for 12 h, the targeted sequence was successfully amplified by PCR and the 704-bp DNA fragment was observed by gel electrophoresis. The total completion of this assay requires less than one day.

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Performance of Turbo Codes in the Direct Detection Optical PPM Channel (직접 검파 펄스 위치 변조 광통신 채널에서의 터보 부호의 성능)

  • 이항원;이상민
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.6C
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    • pp.570-579
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    • 2003
  • The performance of turbo codes is investigated in the direct detection optical PPM channel. We assume that an ideal photon counter is used as an optical detector and that the channel has background noise as well as quantum noise. Resulting channel model is M-ary PPM Poisson channel. We propose the structure of the transmitter and receiver for applying turbo codes to this channel. We also derive turbo decoding algorithm for the proposed coding system, by modifying the calculation of the branch metric inherent in the original turbo decoding algorithm developed for the AWGN channel. Analytical bounds are derived and computer simulation is performed to analyze the performance of the proposed coding scheme, and the results are compared with the performances of Reed-Solomon codes and convolutional codes.

Development and evaluation of semi-nested PCR for detection of the variable lipoprotein haemagglutinin (vlhA) gene of Mycoplasma Synoviae in chicken

  • Pohuang, Tawatchai;Phuektes, Patchara;Junnu, Sucheeva
    • Korean Journal of Veterinary Research
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    • v.60 no.3
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    • pp.109-116
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    • 2020
  • This study aimed to develop a semi-nested polymerase chain reaction assay for the direct detection of Mycoplasma synoviae (M. synoviae) from clinical samples using three newly designed oligonucleotide primers specific to the variable lipoprotein haemagglutinin (vlhA) gene and differentiate M. synoviae field strains based on a nucleotide deletion or the insertion of the proline-rich repeat (PRR) region of the vlhA gene. The developed semi-nested polymerase chain reaction (PCR) assay revealed positive results in 12 out of 100 clinical samples collected from chickens showing lameness and joint swelling. Six positive samples were selected randomly for sequencing, and sequence analysis revealed 96.3-100% nucleotide identities compared to the reference sequences. Phylogenetic analysis showed that sequences of the strains in this study were closely related to WVU1853 (Spain), CK.MS.UDL.PK.2014.2 (Pakistan), and F10-2AS (USA) strains, but they were distinct from the M. synoviae-H vaccine strain sequence. M. synoviae obtained from these samples were identified as types A and C with a length of 38 and 32 amino acids, respectively. These results indicated that the specific and sensitive semi-nested PCR could be a useful diagnostic tool for the direct identification of clinical samples, and the sequence analysis of the partial vlhA gene can be useful for typing M. Synoviae.

Etching-Bonding-Thin film deposition Process for MEMS-IR SENSOR Application (MEMS-IR SENSOR용 식각-접합-박막증착 기반공정)

  • Park, Yun-Kwon;Joo, Byeong-Kwon;Park, Heung-Woo;Park, Jung-Ho;Yom, S.S.;Suh, Sang-Hee;Oh, Myung-Hwan;Kim, Chul-Ju
    • Proceedings of the KIEE Conference
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    • 1998.07g
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    • pp.2501-2503
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    • 1998
  • In this paper, the silicon-nitride membrane structure for IR sensor was fabricated through the etching and the direct bonding. The PTO layer as a IR detection layer was deposited on the membrane and its characteristics were measured. The attack of PTO layer during the etching of silicon wafer as well as the thermal isolation of the IR detection layer can be solved through the method of bonding/etching of silicon wafer. Because the PTO layer of c-axial orientation raised thermal polarization without polling, the more integration capability can be achieved. The surface roughness of the membrane was measured by AFM, the micro voids and the non-contacted area were inspected by IR detector, and the bonding interface was observed by SEM. The polarization characteristics and the dielectric characteristics of the PTO layer were measured, too.

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Design of Input Filters Considering the Stability of STATCOM Systems

  • Zhao, Guopeng;Liu, Jinjun;Han, Minxiao
    • Journal of Power Electronics
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    • v.11 no.6
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    • pp.904-913
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    • 2011
  • Previous publications regarding the design and specifications of input filters for STATCOMs usually deal with the input filter only, and seldom pay any attention to the influence of the input filters on the performance of the STATCOM systems. A detailed analysis of the influences of input filters on the stability of STATCOM systems and the corresponding design considerations are presented in this paper. Three types of input filters, L filters, LC filters, and LCL filters, are examined separately. The influences of the parameters of input filters on system stability are investigated through frequency domain methods. With direct current control taken as the major control strategy for the STATCOMs, the different situations when adopting different current detection points are covered in this analysis. A comparison between LC filters and LCL filters is also presented with optimized filter parameters. Based on the analysis, the phase margin, as one of the design considerations for the different types of input filters under different current detection schemes, is discussed. This leads to filter parameters that are different than those of the traditional design. Hardware experimental results verify the validity of the above analysis and design.

Gross Error Detection and Determination of Exterior Orientation Elements in Non-metric Photos (비측량용(非測量用) 사진(寫眞)에서의 과대오차(過大誤差) 검출(檢出) 및 외부표정요소(外部標定要素) 결정(決定))

  • Yeu, Bock Mo;Sohn, Duke Jae;Park, Hong Gi
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.7 no.4
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    • pp.125-132
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    • 1987
  • The bundle adjustment used in photogrammetric data reduction is based on the collinearity condition. Photogrammetry has been used in many non-topographic applications. Due to the necessities of having fiducial marks and knowing initial approximations for interior and exterior orientation elements in bundle adjustment, it cannot be applied when non-metric cameras are used. Marzan and Karara develop the DLT(Direct Linear Transformation) program which directly transforms comparator coordinates into object space coordinates without approximate values. In this paper, several modifications of original DLT program have been made for accuracy improvement in close-range photogrammetry using non-metric cameras. In modified program, gross error detection method and computation of exterior orientation elements are incorporated, and more iterations are introdued.

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Neutron spectroscopy using pure LaCl3 crystal and the dependence of pulse shape discrimination on Ce-doped concentrations

  • Vuong, Phan Quoc;Kim, Hongjoo;Luan, Nguyen Thanh;Kim, Sunghwan
    • Nuclear Engineering and Technology
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    • v.53 no.11
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    • pp.3784-3789
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    • 2021
  • We report a simple technique for direct neutron spectroscopy using pure LaCl3 crystals. Pure LaCl3 crystals exhibit considerably better pulse shape discrimination (PSD) capabilities with relatively good energy resolution as compared with Ce-doped LaCl3 crystals. Single crystals of pure and Ce-doped LaCl3 were grown using an inhouse-developed Bridgman furnace. PSD capabilities of these crystals were investigated using 241Am and 137Cs sources. Fast neutron detection was tested using a252Cf source and three separate bands corresponding to electron, proton, and alpha were observed. The proton band induced by the 35Cl(n,p)35S reaction can be used for direct neutron spectroscopy because proton energy is proportional to incident neutron energy. Owing to good scintillation performance and excellent PSD capabilities, pure LaCl3 is a promising candidate for space detectors and other applications that necessitate gamma/fast neutron discrimination capability.

Target Recognition Triggered Split DNAzyme based Colorimetric Assay for Direct and Sensitive Methicillin-Resistance Analysis of Staphylococcus aureus

  • Jin Xu;Dandan Jin;Zhengwei Wang
    • Journal of Microbiology and Biotechnology
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    • v.34 no.6
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    • pp.1322-1327
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    • 2024
  • The accurate and rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) holds significant clinical importance. This work presents a new method for detecting methicillin-resistant Staphylococcus aureus (S. aureus) in clinical samples. The method uses an aptamer-based colorimetric assay that combines a recognizing probe to identify the target and split DNAzyme to amplify the signal, resulting in a highly sensitive and direct analysis of methicillin-resistance. The identification of the PBP2a protein on the membrane of S. aureus in clinical samples leads to the allosterism of the recognizing probe, and thus provides a template for the proximity ligation of split DNAzyme. The proximity ligation of split DNAzyme forms an intact DNAzyme to identify the loop section in the L probe and generates a nicking site to release the loop sequence ("3" and "4" fragments). The "3" and "4" fragments forms an intact sequence to induce the catalytic hairpin assembly, exposing the G-rich section. The released the G-rich sequence of LR probe induces the formation of G-quadruplex-hemin DNAzyme as a colorimetric signal readout. The absorption intensity demonstrated a strong linear association with the logarithm of the S. aureus concentration across a wide range of 5 orders of magnitude dynamic range under the optimized experimental parameters. The limit of detection was calculated to be 23 CFU/ml and the method showed high selectivity for MRSA.

The Detection and a Quantitative Evaluation of Viable but Non-Culturable Soil Bacteria Using a Modified Direct Viable Count Method (변형된 DVC법을 이용한 난배양성 토양세균의 검출 및 정량적 평가)

  • 황경숙;양희찬;염곡효
    • Korean Journal of Microbiology
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    • v.39 no.3
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    • pp.181-186
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    • 2003
  • This study was performed to analyze quantitatively the number of living bacteria in forest soil samples collected from Mt. Keryong using improved direct viable count (DVC) and plate count (PC) methods. The number of living bacteria by DVC comprised 18~44% of the total direct count (TDC), whereas the number of living bacteria by PC was less than 1% of TDC. These results showed that viable but non-culturable (VBNC) bacteria existed in the soil with high percentages. Besides, DVC was proved to make it possible to make a quantitative detection of the VBNC bacteria. On the other hand, upon measuring the value from the conventional nutrient broth (NB) and $10^{-2}$ folded diluted nutrient broth (DNB), the values from the DNB showed 5 to 10 times higher than those from the conventional NB medium. These results indicate that oligotrophic bacterial groups, which could multiply in the low nutrient broth, abundantly exist in the soil ecosystem. It would also be possible to apply this kind of method to other substrate to make a quantitative detection of soil bacterial groups.

Design and Implementation of the Intrusion Detection Pattern Algorithm Based on Data Mining (데이터 마이닝 기반 침입탐지 패턴 알고리즘의 설계 및 구현)

  • Lee, Sang-Hoon;Soh, Jin
    • The KIPS Transactions:PartC
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    • v.10C no.6
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    • pp.717-726
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    • 2003
  • In this paper, we analyze the associated rule based deductive algorithm which creates the rules automatically for intrusion detection from the vast packet data. Based on the result, we also suggest the deductive algorithm which creates the rules of intrusion pattern fast in order to apply the intrusion detection systems. The deductive algorithm proposed is designed suitable to the concept of clustering which classifies and deletes the large data. This algorithm has direct relation with the method of pattern generation and analyzing module of the intrusion detection system. This can also extend the appication range and increase the detection speed of exiting intrusion detection system as the rule database is constructed for the pattern management of the intrusion detection system. The proposed pattern generation technique of the deductive algorithm is used to the algorithm is used to the algorithm which can be changed by the supporting rate of the data created from the intrusion detection system. Fanally, we analyze the possibility of the speed improvement of the rule generation with the algorithm simulation.