scholarly journals An assessment of true and false positive detection rates of stepwise epistatic model selection as a function of sample size and number of markers

Heredity ◽  
2018 ◽  
Vol 122 (5) ◽  
pp. 660-671 ◽  
Author(s):  
Angela H. Chen ◽  
Weihao Ge ◽  
William Metcalf ◽  
Eric Jakobsson ◽  
Liudmila Sergeevna Mainzer ◽  
...  
Keyword(s):  
Model Selection ◽  
Sample Size ◽  
False Positive ◽  
Detection Rates ◽  
Epistatic Model ◽  
False Positive Detection

scholarly journals Head-mounted accelerometry accurately detects prey capture in California sea lions

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Mason R. Cole ◽  
Jenifer A. Zeligs ◽  
Stefani Skrovan ◽  
Birgitte I. McDonald
Keyword(s):  
False Positive ◽  
Prey Capture ◽  
Sampling Rate ◽  
Mouth Opening ◽  
True Positive ◽  
Underwater Video ◽  
California Sea Lions ◽  
Detection Rates ◽  
Sea Lions ◽  
False Positive Detection

AbstractDetecting when and where animals feed is key to understanding their ecophysiology, but our ability to collect these data in marine mammals remains limited. Here, we test a tag-based accelerometry method to detect prey capture in California sea lions. From synchronized underwater video and acceleration data of two trained sea lions, we isolated a combined acceleration and Jerk pattern that reliably indicated prey capture in training datasets. We observed a stereotyped feeding motion in underwater video that included (1) mouth opening while approaching prey; (2) head deceleration to allow initial suction or prey engulfment, and (3) jaw closure. This motion (1–3) was repeated if a prey item was not initially engulfed. This stereotyped feeding motion informed a signal pattern phrase that accurately detected feeding in a training dataset. This phrase required (1) an initial heave-axis Jerk signal surpassing a threshold based on sampling rate; (2) an estimated dynamic surge-axis deceleration signal surpassing −0.7 g beginning within 0.2 s of the initial Jerk signal; and (3) an estimated dynamic surge-axis acceleration signal surpassing 1.0 g within 0.5 s of the beginning of the prior deceleration signal. We built an automated detector in MATLAB to identify and quantify these patterns. Blind tests of this detector on non-training datasets found high true-positive detection rates (91%–100%) with acceleration sampled at 50–333 Hz and low false-positive detection rates (0%–4.8%) at all sampling rates (16–333 Hz). At 32 Hz and below, true-positive detection rates decreased due to attenuation of signal detail. A detector optimized for an adult female was also accurate at 32–100 Hz when tested on an adult male’s data, suggesting the potential future use of a generalized detector in wild subjects. When tested on the same data, a published triaxial Jerk method produced high true-positive detection rates (91–100%) and low-to-moderate false-positive detection rates (15–43%) at ≥ 32 Hz. Using our detector, larger prey elicited longer prey capture duration in both animals at almost all sampling rates 32 Hz or faster. We conclude that this method can accurately detect feeding and estimate relative prey length in California sea lions.

Predicting Fetal Chromosome Anomalies in the First Trimester Using Pregnancy Associated Plasma Protein-A: A Comparison of Statistical Methods

1993 ◽  
Vol 32 (02) ◽  
pp. 175-179 ◽  
Author(s):  
B. Brambati ◽  
T. Chard ◽  
J. G. Grudzinskas ◽  
M. C. M. Macintosh
Keyword(s):  
Logistic Regression ◽  
General Population ◽  
Likelihood Ratio ◽  
False Positive ◽  
False Positive Rate ◽  
Ratio Method ◽  
Detection Rates ◽  
Gaussian Distributions ◽  
Positive Rate ◽  
Likelihood Ratio Method

Abstract:The analysis of the clinical efficiency of a biochemical parameter in the prediction of chromosome anomalies is described, using a database of 475 cases including 30 abnormalities. A comparison was made of two different approaches to the statistical analysis: the use of Gaussian frequency distributions and likelihood ratios, and logistic regression. Both methods computed that for a 5% false-positive rate approximately 60% of anomalies are detected on the basis of maternal age and serum PAPP-A. The logistic regression analysis is appropriate where the outcome variable (chromosome anomaly) is binary and the detection rates refer to the original data only. The likelihood ratio method is used to predict the outcome in the general population. The latter method depends on the data or some transformation of the data fitting a known frequency distribution (Gaussian in this case). The precision of the predicted detection rates is limited by the small sample of abnormals (30 cases). Varying the means and standard deviations (to the limits of their 95% confidence intervals) of the fitted log Gaussian distributions resulted in a detection rate varying between 42% and 79% for a 5% false-positive rate. Thus, although the likelihood ratio method is potentially the better method in determining the usefulness of a test in the general population, larger numbers of abnormal cases are required to stabilise the means and standard deviations of the fitted log Gaussian distributions.

Investigation and Resolution of Interference in the LC-QTOF-MS Detection of 4-MePPP

2021 ◽  
Author(s):  
Darren R Allen ◽  
Christopher Warnholtz ◽  
Brett C McWhinney
Keyword(s):  
Reference Material ◽  
Spectral Data ◽  
False Positive ◽  
In Silico ◽  
Spectral Library ◽  
In Silico Fragmentation ◽  
False Positive Detection ◽  
Product Ions ◽  
Synthetic Cathinone ◽  
Recent Addition

Abstract An interference resulting in the false-positive detection of the synthetic cathinone 4-MePPP in urine was suspected following the recent addition of 4-MePPP spectral data to an LC-QTOF-MS drug library. Although positive detection criteria were achieved, it was noted that all urine samples suspected of containing 4-MePPP also concurrently contained high levels of tramadol and its associated metabolites. Using QTOF-MS software elucidation tools, candidate compounds for the suspected interference were proposed. To provide further confidence in the identity of the interference, in silico fragmentation tools were used to match product ions generated in the analysis with product ions predicted from the theoretical fragmentation of candidate compounds. The ability of the suspected interference to subsequently produce the required product ions for spectral library identification of 4-MePPP was also tested. This information was used to provide a high preliminary confidence in the compound identity prior to purchase and subsequent confirmation with certified reference material. A co-eluting isobaric interference was identified and confirmed as an in-source fragment of the tramadol metabolite, N,N-bisdesmethyltramadol. Proposed resolutions for this interference are also described and subsequently validated by retrospective interrogation of previous cases of suspected interference.

scholarly journals Importance of Inoculum Size and Sampling Effect in Rapid Antigen Detection for Diagnosis of Streptococcus pyogenes Pharyngitis

2000 ◽  
Vol 38 (1) ◽  
pp. 279-281 ◽  
Author(s):  
Bradley Kurtz ◽  
Michael Kurtz ◽  
Martha Roe ◽  
James Todd
Keyword(s):  
Sample Size ◽  
Streptococcus Pyogenes ◽  
Disease Status ◽  
Inoculum Size ◽  
Antigen Detection ◽  
Detection Rates ◽  
Sample Distribution ◽  
Antigen Tests ◽  
The One ◽  
Antigen Testing

ABSTRACT Current recommendations suggest that negative rapid Streptococcus pyogenes antigen tests be backed up with a culture, reflecting evidence that culture may have a higher sensitivity and also that testing of a second swab may yield a different (i.e., a positive) result because of variation in sample size or distribution. If the latter is common, the sensitivities of current antigen detection tests might be improved by simply increasing the amount of sample tested. The present study assessed the effect of antigen testing of two swabs extracted together compared to independent testing of each swab extracted separately for children with clinical pharyngitis. S. pyogenes grew from one or both swabs for 198 (37%) of 537 children. The combined culture was significantly ( P < 0.05) more sensitive than culture of either swab alone. Compared to combined culture, antigen testing of two swabs extracted and tested together was significantly more sensitive than two single swab extractions (94.1 versus 80%; P = 0.03); however, the specificity was decreased (81.5 versus 89.8 to 92.7%; P < 0.05). This study suggests that sample size and/or uneven sample distribution may have influenced the apparent sensitivities of prior studies that compared antigen tests to a single plate culture. A strategy, such as the one used in the present study, that increases the sample size available for antigen testing (i.e., extraction of samples from both swabs) may improve detection rates to a level that will better approximate true disease status and obviate the need for backup cultures if specificity can be improved.

scholarly journals Visual techniques for cervical cancer screening in Colombia

Biomédica ◽  
2019 ◽  
Vol 39 (1) ◽  
pp. 65-74
Author(s):  
Óscar Gamboa ◽  
Mauricio González ◽  
Jairo Bonilla ◽  
Joaquín Luna ◽  
Raul Murillo ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Cancer Screening ◽  
Cervical Cancer Screening ◽  
False Positive ◽  
Gold Standard ◽  
Visual Inspection ◽  
Low Grade ◽  
High Grade ◽  
Detection Rates ◽  
Lower Detection

Introduction: Direct visual inspection for cervical cancer screening remains controversial, whereas colposcopy-biopsy is considered the gold standard for diagnosis of preneoplastic cervical lesions.Objectives: To determine the rates of cervical intraepithelial neoplasia grade 2 or more and of false positives for colposcopy and direct visual inspection.Materials and methods: Women aged 25-59 underwent direct visual inspection with acetic acid (VIA), Lugol’s iodine (VIA-VILI), and colposcopy. Punch biopsies were obtained for all positive tests. Using histology as the gold standard, detection and false positive rates were compared for VIA, VIA-VILI, and colposcopy (two thresholds). Sensitivity and false positive ratios with the corresponding 95% confidence intervals were estimated.Results: We included 5,011 women in the analysis and we obtained 602 biopsies. Positivity rates for colposcopy high-grade and low-grade diagnosis were 1.6% and 10.8%. Positivity rates for VIA and VIA-VILI were 7.4% and 9.9%. VIA showed a significantly lower detection rate than colposcopy with low-grade diagnosis as the threshold (SR=0.72; 95% CI 0.57-0.91), and significantly lower false positive rate (FPR=0.70; 95% CI 0.65-0.76). No differences between VIA-VILI and colposcopy low-grade threshold were observed. VIA and VIA-VILI showed significantly higher detection and false positive rates than colposcopy high-grade threshold. Sensitivity rates for visual inspection decreased with age and false positive rates increased. For all age groups, false positive rates for VIA and VIA-VILI were significantly higher than colposcopy.Conclusions: Detection rates for VIA-VILI similar to colposcopy low-grade threshold represent a chance to reduce cervical cancer mortality through see-and-treat approaches among women with limited access to health care. Lower detection rates suggest reviewing high-grade colposcopy findings as the threshold for biopsy in certain settings.

scholarly journals Triage of hrHPV-positive women: comparison of two commercial methylation-specific PCR assays

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Carolin Dippmann ◽  
Martina Schmitz ◽  
Kristina Wunsch ◽  
Stefanie Schütze ◽  
Katrin Beer ◽  
...  
Keyword(s):  
Dna Methylation ◽  
False Positive ◽  
Pap Smear ◽  
Intraepithelial Neoplasia ◽  
Molecular Diagnostic ◽  
Cervical Lesions ◽  
Detection Rates ◽  
Diagnostic Assays ◽  
Specific Pcr

Abstract Aim High-risk human papillomavirus (hrHPV)-based screening is becoming increasingly important, either by supplementing or replacing the traditional cytology-based cervical Pap smear. However, hrHPV screening lacks specificity, because it cannot differentiate between transient virus infection and clinically relevant hrHPV-induced disease. Therefore, reliable triage methods are needed for the identification of HPV-positive women with cervical intraepithelial neoplasia (CIN) in need of treatment. Promising tools discussed for the triage of these patients are molecular diagnostic tests based on epigenetic markers. Here, we compare the performance of two commercially available DNA methylation-based diagnostic assays—GynTect® and the QIAsure Methylation Test—in physician-taken cervical scrapes from 195 subjects. Findings Both GynTect® and the QIAsure Methylation Test detected all cervical carcinoma and carcinoma in situ (CIS). The differences observed in the detection rates between both assays for the different grades of cervical lesions (QIAsure Methylation Test: CIN1 26.7%, CIN2 27.8% and CIN3 74.3%; GynTect®: CIN1 13.3%, CIN2 33.3% and CIN3 60%) were not significant. Concerning the false-positive rates, significant differences were evident. For the healthy (NILM) hrHPV-positive group, the false-positive rates were 5.7% for GynTect® and 26.4% for QIAsure Methylation Test (p = 0.003) and for the NILM hrHPV-negative group 2.2% vs. 23.9% (p = 0.006), respectively. When considering hrHPV-positive samples only for comparison (n = 149), GynTect® delivered significantly higher specificity compared to the QIAsure Methylation Test for CIN2 + (87.6% vs. 67.4% (p < 0.001)) and CIN3 + (84.1% vs. 68.2% (p = 0.002)). Overall our findings suggest that DNA methylation-based tests are suitable for the triage of hrHPV-positive women. With the goal to provide a triage test that complements the limited specificity of HPV testing in HPV-based screening, GynTect® may be preferable, due to its higher specificity for CIN2+ or CIN3+ .

scholarly journals False Positive Decremented Research for Fire and Smoke Detection in Surveillance Camera using Spatial and Temporal Features Based on Deep Learning

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1167 ◽  
Author(s):  
Yeunghak Lee ◽  
Jaechang Shim
Keyword(s):  
Deep Learning ◽  
False Positive ◽  
Learning Algorithm ◽  
Detection Performance ◽  
Economic Losses ◽  
Smoke Detection ◽  
Temporal Features ◽  
False Positive Detection ◽  
Surveillance Cameras ◽  
Fire Flame

Fire must be extinguished early, as it leads to economic losses and losses of precious lives. Vision-based methods have many difficulties in algorithm research due to the atypical nature fire flame and smoke. In this study, we introduce a novel smoke detection algorithm that reduces false positive detection using spatial and temporal features based on deep learning from factory installed surveillance cameras. First, we calculated the global frame similarity and mean square error (MSE) to detect the moving of fire flame and smoke from input surveillance cameras. Second, we extracted the fire flame and smoke candidate area using the deep learning algorithm (Faster Region-based Convolutional Network (R-CNN)). Third, the final fire flame and smoke area was decided by local spatial and temporal information: frame difference, color, similarity, wavelet transform, coefficient of variation, and MSE. This research proposed a new algorithm using global and local frame features, which is well presented object information to reduce false positive based on the deep learning method. Experimental results show that the false positive detection of the proposed algorithm was reduced to about 99.9% in maintaining the smoke and fire detection performance. It was confirmed that the proposed method has excellent false detection performance.

Impact of Including or Removing Nuchal Translucency Measurement on the Detection and False-Positive Rates of First-Trimester Down Syndrome Screening

2015 ◽  
Vol 40 (3) ◽  
pp. 214-218 ◽  
Author(s):  
Emmanuel Spaggiari ◽  
Isabelle Czerkiewicz ◽  
Corinne Sault ◽  
Sophie Dreux ◽  
Armelle Galland ◽  
...  
Keyword(s):  
Down Syndrome ◽  
False Positive ◽  
False Positive Rate ◽  
Method Comparison ◽  
First Trimester ◽  
Nuchal Translucency ◽  
Routine Practice ◽  
Detection Rates ◽  
Significant Difference ◽  
Positive Rate

Introduction: First-trimester Down syndrome (DS) screening combining maternal age, serum markers (pregnancy-associated plasma protein-A and beta-human chorionic gonadotropin) and nuchal translucency (NT) gives an 85% detection rate for a 5% false-positive rate. These results largely depend on quality assessment of biochemical markers and of NT. In routine practice, despite an ultrasound quality control organization, NT images can be considered inadequate. The aim of the study was to evaluate the consequences for risk calculation when NT measurement is not taken into account. Material and Method: Comparison of detection and false-positive rates of first-trimester DS screening (PerkinElmer, Turku, Finland), with and without NT, based on a retrospective study of 117,126 patients including 274 trisomy 21-affected fetuses. NT was measured by more than 3,000 certified sonographers. Results: There was no significant difference in detection rates between the two strategies including or excluding NT measurement (86.7 vs. 81.8%). However, there was a significant difference in the false-positive rates (2.23 vs. 9.97%, p < 0.001). Discussion: Sonographers should be aware that removing NT from combined first-trimester screening would result in a 5-fold increase in false-positive rate to maintain the expected detection rates. This should be an incentive for maintaining quality in NT measurement.

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