• Title/Summary/Keyword: False-negative results

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Clinical Usefulness of Helicobactor pylori Ag Stool Test (Immunochromatographic Assay) for Diagnosis of H. pylori Infection (Helicobacter pylori 감염진단에 있어 H. pylori Ag Stool 검사 (면역크로마토그라피법)의 임상적 유용성)

  • Seo, Seol
    • Korean Journal of Clinical Laboratory Science
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    • v.42 no.1
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    • pp.38-45
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    • 2010
  • The aim of this study was to assess the Clinical Usefulness of Helicobacter pylori Stool Antigen (HpSA) immunochromatographic assay for the diagnosis of H. pylori infection. In this study, we had compared HpSA-immunochromatographic assay with CLO test and UBT test. From a total of 140 patients (M:F=88:52) with upper endoscopy, biopsy specimens were obtained for CLO test. Stool specimens was collected from all patients and tested using a HpSA-immunochromatic assay. H. pylori infection status was defined as infected if the results of both CLO test and UBT test were positive. CLO test and UBT test findings showed that 92 patients were H. pylori positive and 48 patients were H. pylori negative. According to this definition, the sensitivity, specificity, and positive or negative predictive value (PPV, NPV) of HpSA-immunochromatographic assay were 97.8%, 100%, 100%, and 96%, respectively. Cross reactivity test of HpSA-immunochromatographic assay were performed with 10 enteric bacteria strains in fecal habitat, and there were no false positive reaction. We evaluated the usefulness of HpSA assay for eradication therapy with 10 of 92 H. pylori positive patients, positive results of them at pre-eradication therapy were converted to negative at post-eradication. The HpSA-immunochromatographic assay is a highly sensitive and specific non-invasive diagnostic method for detection of H. pylori infection, a useful diagnostic method for H. pylori in post eradication stage.

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Identification of Staphylococcus hyicus subsp hyicus of swine and poultry origin by API STAPH-IDENT system (API STAPH-IDENT system에 의한 돼지 및 닭유래(由來) staphylococcus hyicus subsp hyicus의 동정(同定))

  • Park, Cheong-kyu
    • Korean Journal of Veterinary Research
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    • v.34 no.2
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    • pp.315-320
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    • 1994
  • The API STAPH-IDENT system was evaluated as a means for identifying Staphylococcus hyicus subsp hyicus straints isolated from swine and poultry. Of 80 strains from swine, 68 (85%) were correctly identified by the API STAPH-IDENT system alone after 5 h of incubation. When results were determined after 24 h of incubation, the accuracy of this system alone was 93.8%. By additional tests in conjunction with the API STAPH-IDENT system, however, all 80 strains could be correctly identified. Of 120 strains from poultry, 87 (72.5%) required additional testing to achieve a correct identification, and 33 (27.5%) were incorrectly identified by this system after 5 h of incubation. After 24 h of incubation, 99 of 120 (82.5%) avian strains were incorrectly identified as Staph epidermidis owing to false-negative mannose and trehalose utilizations. Seventy-seven (96.3%) of swine strains were positive for ${\beta}-glucuronidase$, whereas all 120 strains recovered tram poultry were negative for it.

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A Comparative Analysis on The Efficiency of Various Clinical Methods for Diagnosis of Tuberculosis (결핵 진단을 위한 검사 방법간의 효율성에 관한 비교 분석)

  • 최석철;정천환;성희경;김태운;이원재
    • Biomedical Science Letters
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    • v.5 no.2
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    • pp.191-200
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    • 1999
  • In recent years continuously increasing number of tuberculosis (TB) cases due to the emergence of strains with multidrug resistance and AIDS is a significant global health problem. Therefore, more rapid and reliable diagnosis of TB may be one of the most urgent needs in efforts to eradicate the disease. The present study was designed to compare and assess the diagnostic values and efficiencies between the conventional methods (X-ray, AFB stain and culture) and PCR for pulmonary TB on 171 cases. Chest X-ray finding and clinical features revealed that 39 (22.8%) of 171 sputum specimens were pulmonary TB cases. The statistical data were taken on the basis of the definitive diagnosis: In X-ray, overall sensitivity, specificity, efficiency and false positive and false negative incidence was respectively 69.2%, 87.1%, 83.0%, 12.9%, and 30.8%; 79.5%, 95.5%, 91.8%,4.6% and 20.5% in AFB-stain; 56.4%, 99.2%,89.5%, 0.8% and 43.6% in culture; 82.1%, 96.2%, 93.0%, 3.8% and 17.9% in PCR. PCR got a highest sensitivity and efficiency as well as a lowest false negative incidence. Culture had a highest specificity with a lowest false positive incidence. These results imply that PCR assay is fast, sensitive and efficient method for diagnosis of pulmonary TB. However, combined use of the conventional methods with thorough quality control may offer more opportunities for detecting Mycobacterium tuberculosis and diagnosting TB although they have some limits.

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Application of Symbolic Representation Method for Fault Detection and Clustering in Semiconductor Fabrication Processes (반도체공정 이상탐지 및 클러스터링을 위한 심볼릭 표현법의 적용)

  • Loh, Woong-Kee;Hong, Sang-Jeen
    • Journal of KIISE:Computing Practices and Letters
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    • v.15 no.11
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    • pp.806-818
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    • 2009
  • Since the invention of the integrated circuit (IC) in 1950s, semiconductor technology has undergone dramatic development up to these days. A complete semiconductor is manufactured through a diversity of processes. For better semiconductor productivity, fault detection and classification (FDC) has been rigorously studied for finding faults even before the processes are completed. For FDC, various kinds of sensors are attached in many semiconductor manufacturing devices, and sensor values are collected in a periodic manner. The collection of sensor values consists of sequences of real numbers, and hence is regarded as a kind of time-series data. In this paper, we propose an algorithm for detecting and clustering faults in semiconductor processes. The proposed algorithm is a modification of the existing anomaly detection algorithm dealing with symbolically-represented time-series. The contributions of this paper are: (1) showing that a modification of the existing anomaly detection algorithm dealing with general time-series could be used for semiconductor process data and (2) presenting experimental results for improving correctness of fault detection and clustering. As a result of our experiment, the proposed algorithm caused neither false positive nor false negative.

Screening for Colorectal Neoplasias with Fecal Occult Blood Tests: False-positive Impact of Non-Dietary Restriction

  • Roslani, April Camilla;Abdullah, Taufiq;Arumugam, Kulenthran
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.1
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    • pp.237-241
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    • 2012
  • Objective: Screening for colorectal cancer using guaiac-based fecal occult blood tests (gFOBT) is well established in Western populations, but is hampered by poor patient compliance due to the imposed dietary restrictions. Fecal immunochemical tests (FIT) do not require dietary restriction, but are more expensive than gFOBT and therefore restrict its use in developing countries in Asia. However, Asian diets being low in meat content may not require diet restriction for gFOBT to achieve equivalent results. The objective of this study was to evaluate and compare the validity and suitability of gFOBT and FIT or a combination of the two in screening for colorectal neoplasias without prior dietary restriction in an Asian population. Methods: Patients referred to the Endoscopic Unit for colonoscopy were recruited for the study. Stool samples were collected prior to bowel preparation, and tested for occult blood with both gFOBT and FIT. Dietary restriction was not imposed. To assess the validity of either tests or in combination to detect a neoplasm or cancer in the colon, their false positive rates, their sensitivity (true positive rate) and the specificity (true negative rate) were analyzed and compared. Results: One hundred and three patients were analysed. The sensitivity for picking up any neoplasia was 53% for FIT, 40% for gFOBT and 23.3% for the combination. The sensitivities for picking up only carcinoma were 77.8%, 66.7% and 55.5%, respectively. The specificity for excluding any neoplasia was 91.7% for FIT, 74% for gFOBT and 94.5% for a combination, whereas for excluding only carcinomas they were 84%, 73.4% and 93.6%. Of the 69 with normal colonoscopic findings, FOBT was positive in 4.3%, 23.2 %and 2.9% for FIT, gFOBT, or combination of tests respectively. Conclusion: FIT is the recommended method if we are to dispense with dietary restriction in our patients because of its relatively low-false positivity and better sensitivity and specificity rates.

Diagnostic Value of the Intradermal Test for the Infection with Clonorchis sinensis (간흡충증 진단을 위한 피내반응검사의 의의)

  • Kim, Jong-Ho;Yun, Bong-Yung;Lee, Heun-Ju;Lee, Hyun-Woo
    • Journal of Yeungnam Medical Science
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    • v.5 no.2
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    • pp.47-52
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    • 1988
  • The intradermal(ID) test has been widely used in Korea and several reports about the results of the ID test are known. We examined the egg of Clonorchis sinensis(C. s.) by ID test in 443, stool's egg-counting technique in 79 and direct smear(cellophane thick smear technique) in 1304 subjects. The results are as follows.: 1. The positive rate of C. s. was 3.8% out of 1304 persons. 2. The sensitivity of ID test was 82.1% out of 39 persons and, the specificity was 64.6% out of 404 persons. 3. The false positive of ID test 35.4% out of 404 persons and, the false negative was 17.9% out of 39 persons. Intradermal test is a rapid, sensitive and useful supplementary diagnostic tool for the detection of Clonorchiasis infection and must be used as screening test with direct smear of stool but cross reaction with other helminth infections and moderate false reaction are the main disadvantages in its practical application.

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Diagnostic Usefulness of CISS Image in Preoperative Evaluation of Trigeminal Neuralgia and Hemifacial Spasm (삼차신경통과 반측안면경련에서 CISS 영상의 진단적 유용성)

  • Lee, Dong Hoon;Lee, Sang Weon;Choi, Chang Hwa
    • Journal of Korean Neurosurgical Society
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    • v.30 no.2
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    • pp.186-193
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    • 2001
  • Objectives : Trigeminal neuralgia and hemifacial spasm are caused by vascular compression of the REZ(root entry or exit zone) of the 5th and the 7th cranial nerve. Preoperative detection of neurovascular compression is essential for accurate diagnosis, appropriate treatment, and the good operative results. Three dimensional Fourier Transformation-Constructive Interference in Steady State(3DFT-CISS) images are known to give good contrast between CSF, nerve, and vessels. We applied a 3DFT-CISS imaging technique for the preoperative evaluation of patients with these diseases and estimated the diagnostic accuracy and usefulness of this study. Methods : A series of 71 patients with trigeminal neuralgia and hemifacial spasm were treated by microvascular decompression. Among them 34 patients with trigeminal neuralgia and 24 patients with hemifacial spasm had preoperative CISS images. We compared the radiologic finding with the operative finding, and analysed the diagnostic usefulness of 3DFT-CISS imaging. Results : The sensitivity of CISS images of detecting the neurovascular compression was 90.3% in trigeminal neuralgia and 100% in hemifacial spasm. There were one false-positive and three false-negative cases in trigeminal neuralgia, and one false-positive case in hemifacial spasm. The accuracy in diagnosing the causative vessel was 73.5% in trigeminal neuralgia and 83.3% in hemifacial spasm. Conclusion : CISS image is very useful diagnostic tool for preoperative evaluation of neurovascular compression in patients with trigeminal neuralgia and hemifacial spasm. No additional neuroradiologic examination other than CISS image and MRA is needed for preoperative evaluation of patients with trigeminal neuralgia and hemifacial spasm.

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An Ensemble Approach to Detect Fake News Spreaders on Twitter

  • Sarwar, Muhammad Nabeel;UlAmin, Riaz;Jabeen, Sidra
    • International Journal of Computer Science & Network Security
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    • v.22 no.5
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    • pp.294-302
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    • 2022
  • Detection of fake news is a complex and a challenging task. Generation of fake news is very hard to stop, only steps to control its circulation may help in minimizing its impacts. Humans tend to believe in misleading false information. Researcher started with social media sites to categorize in terms of real or fake news. False information misleads any individual or an organization that may cause of big failure and any financial loss. Automatic system for detection of false information circulating on social media is an emerging area of research. It is gaining attention of both industry and academia since US presidential elections 2016. Fake news has negative and severe effects on individuals and organizations elongating its hostile effects on the society. Prediction of fake news in timely manner is important. This research focuses on detection of fake news spreaders. In this context, overall, 6 models are developed during this research, trained and tested with dataset of PAN 2020. Four approaches N-gram based; user statistics-based models are trained with different values of hyper parameters. Extensive grid search with cross validation is applied in each machine learning model. In N-gram based models, out of numerous machine learning models this research focused on better results yielding algorithms, assessed by deep reading of state-of-the-art related work in the field. For better accuracy, author aimed at developing models using Random Forest, Logistic Regression, SVM, and XGBoost. All four machine learning algorithms were trained with cross validated grid search hyper parameters. Advantages of this research over previous work is user statistics-based model and then ensemble learning model. Which were designed in a way to help classifying Twitter users as fake news spreader or not with highest reliability. User statistical model used 17 features, on the basis of which it categorized a Twitter user as malicious. New dataset based on predictions of machine learning models was constructed. And then Three techniques of simple mean, logistic regression and random forest in combination with ensemble model is applied. Logistic regression combined in ensemble model gave best training and testing results, achieving an accuracy of 72%.

Usefulness of FAST for Evaluation of Blunt Abdominal Trauma Patients (복부둔상 환자의 혈복강 진단에 있어 FAST의 유용성에 대한 고찰)

  • Chu, Yong Sik;Kim, Ok Jun;Choi, Sung Uk;Lee, Jung Han
    • Journal of Trauma and Injury
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    • v.19 no.2
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    • pp.135-142
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    • 2006
  • Purpose: We planned to determine the diagnostic capability of focused assessment with sonography for trauma (FAST) in cases of blunt abdominal injury (BAI). Methods: A retrospective analysis of FAST sheets was performed from April 2002 to December 2004. During the study period, 135 BAI patients were evaluated with FAST at the Emergency Department of Bundang CHA Hospital. Of this group, twenty-eight patients were excluded, leaving 107 patients for analysis. Abdomen CT (computerized tomography) or exploratory laparotomy confirmed the presence of hemoperitoneum. At the secondary survey, patients underwent a three-view FAST examination (LogicQ; General Electric, Waukesha, USA) by an emergency physician, followed within 2 hours by an abdomen CT or exploratory laparotomy. The FAST examination was considered positive if it demonstrated evidence of free intra-abdominal fluid. Results: There were 45 true-positive FAST examination, 57 true-negatives, 1 false-positive, and 4 false negatives (sensitivity 91.8%, specificity 98.3%, positive predictive value 97.8%, negative predictive value 93.4%). The area under the ROC curve was 0.951 for the FAST examination. Conclusion: FAST is a highly reliable method for screening patients suspected of having BAI for the presence or absence of hemoperitoneum.

The High-Reliable Image Authentication Technique using Histogram Compensation (히스토그램 보정을 이용한 고신뢰성 영상 인증 기법)

  • Kim, Hyo-Chul
    • Journal of Korea Multimedia Society
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    • v.13 no.7
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    • pp.1088-1094
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    • 2010
  • Image authentication algorithms have to discriminate forged contents in the various critical fields of military, medical services, digital documents. They must ensure perceptual invisibility and fragility against malicious attacks. It is desirable that watermarking algorithms support sufficient insertion capacity and blind feature. And, high reliable algorithms that can eliminate false-positive and false-negative errors are needed in the watermark extraction process. In this paper, we control coefficients of high frequency band in a DCT domain and compensate brightness histogram for high reliability. As a result, we found that the proposed algorithm guarantee various requirements such as perceptual invisibility with high PSNR values, fragility, high reliability and blind feature. In addition, experiment results show that the proposed algorithm can be used steganographic applications by sufficient capacity of watermark.